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1 Select the right matrix resin Usually ultra-high molecular weight polyethylene (PE-UHWM) is one of the most wear-resistant plastics, and the selection of PE-U·HWM can simply improve the wear resistance of the material. In addition, high crystallization, high regularity of the plastic is more wear-resistant, high hardness of the plastic is more wear-resistant, such as polystyrene composed of large molecules such as benzene rings do not wear. In polypropylene (PP) modification, polyolefin elastomer (POE), ethylene propylene terene rubber (EPDM), thermoplastic dynamic vulcanized rubber (TPV) (such as dynamic vulcanized PP/EPDM) is usually used to toughen PP, and the addition of elastomers generally leads to a decline in scratch resistance, so it is very important to choose the appropriate elastomer. The order of scratch resistance is as follows: TPV > EPDM > POE. 2 Packing with good wear resistance (1) Molybdenum disulfide. Molybdenum disulfide is a wear-resistant additive mainly used in nylon plastics. Molybdenum disulfide acts as a crystallizing agent to increase the crystallinity of nylon, so that the nylon material produces a harder and more wear-resistant surface. Molybdenum disulfide has a high affinity for metal, once adsorbed on the metal surface, molybdenum disulfide molecules will fill the metal surface with microscopic pores, and make the metal surface more smooth, which makes molybdenum disulfide an ideal wear-resistant additive for nylon and metal friction occasions. (2) Graphite. The structure of graphite is the crystal structure of mineral graphite, hexagonal layer, this unique chemical structure makes graphite molecules easily slide each other when subjected to little friction, this wear resistance is particularly important in the environment with water, so graphite as an ideal wear-resistant additive used in many parts placed in water, such as water shell, blade and seal. (3) Glass fiber. Glass fiber can form a strong mechanical bond between polymers, so glass fiber can improve the integrity of thermoplastic structures and improve wear resistance. Glass fiber provides reinforcement and can improve the thermal conductivity and thermal deformation of plastics, significantly improving the load resistance and wear resistance of plastics. (4) carbon fiber. Similar to the case of glass fiber, carbon fiber can greatly improve the integrity of the material structure, load resistance and wear resistance. Unlike glass fiber, carbon fiber is a softer and less scratchy fiber, and carbon fiber will not scratch the friction surface of iron or steel against which it is rubbed. (5) Aromatic polyamide fiber. Aromatic polyamide fiber is also one of the wear resistant additives, unlike glass fiber and carbon fiber, it is the softest and most scratch free fiber, this property is the main advantage of aromatic polyamide fiber in wear resistant applications. 3 Add suitable wear-resisting additives (1) Polytetrafluoroethylene (PTFE). Polytetrafluoroethylene (PTFE) has a very low coefficient of friction, and PTFE molecules form a lubricating film on the surface of the part during friction. PTFE has good lubricity and wear resistance under friction, and is the best wear resistant additive in high load applications. These high-load applications include hydraulic piston ring seals and thrust washers. The PTFE content in amorphous plastics is generally 15%, and in crystalline plastics is generally 20%. (2) polysiloxane. Polysiloxane liquid is a migratory wear-resistant additive that, when added to thermoplastics, slowly migrates to the surface of the part and forms a continuous film. If the viscosity of polysiloxane is too low, the more quickly it can migrate to the surface of the part to provide wear resistance, but the viscosity of polysiloxane can not be too low, otherwise it is easy to volatilize and will quickly disappear from the part. (3) Smoothing agent. Such as oleic acid amide, erucic acid amide and other smoothing agents, when they are added to the thermoplastic, will migrate to the surface of the part to produce a wax layer, reducing the coefficient of friction while also reducing the visibility of scratches, the disadvantage is that it can not completely improve the surface sticky phenomenon.

Color changes caused by plastic molding processing 1. During high temperature molding, the matrix resin is oxidized, degraded and discolored When the heating ring or heating plate of plastic molding processing equipment has been in a heating state due to loss of control, it is easy to lead to local temperature is too high, making the resin oxidation and decomposition at high temperature, for those heat-sensitive plastics, such as PVC, etc., this phenomenon is more likely to occur during molding processing, when serious, it will burn yellow, or even black, and accompanied by a large number of low molecular volatiles escape. This degradation includes depolymerization, random chain breaking, side group and low molecular matter removal and other reactions. (1) Depolymerization The depolymerization system breaks at the end of the macromolecule first, and then removes the monomer rapidly according to the linkage mechanism, especially when the polymerization temperature is above the upper limit. (2) Random chain break (degradation) For polymers such as PE at high temperature molding, its main chain can be broken at any position, the molecular weight rapidly decreases, but the monomer yield is very small, this reaction is called random chain break, sometimes also known as degradation, polyethylene chain break formed after the free radical activity is very high, there are more secondary hydrogen around, easy to occur chain transfer reaction, almost no monomer production. (3) Removal of substituents When polyvinyl chloride, polyvinyl acetate, polyacrylonitrile, polyvinyl fluoride, etc., are heated, substituents will be removed. Taking polyvinyl chloride (PVC) as an example, PVC is processed at temperatures below 180~200 ° C, but at lower temperatures (such as 100~120 ° C), that is, begins to dehydrogenate (HCl), about 200 ° C loses HCl quickly, and the polymer becomes dark and the strength becomes low, the total reaction is summarized as follows: ~ CH2CHCICH2CHCl ~ → ~ CH=CHCH=CH ~ +2HCl Free HCl has a catalytic effect on dehydrochlorination, and metal chlorides, such as ferric chloride formed by hydrogen chloride and processing equipment, promote catalysis: 3HCl+Fe→FeCl3+3HCl PVC in hot processing must add a few percent of the acid absorbent, such as barium stearate, organotin, lead compounds, etc., to improve its stability. If the polyolefin layer on the copper wire is not stable, green copper carboxylate will be formed on the polymer-copper interface when the telecommunication cable is colored. These reactions promote the diffusion of copper into the polymer and accelerate the catalytic oxidation of copper. Therefore, in order to reduce the oxidative degradation rate of polyolefin, phenols or arylamine antioxidants (AH) are often added to terminate the above reaction and form inactive free radicals A· : ROO·+AH-→ROOH+A· (4) Oxidative degradation Polymers are exposed to oxygen in the air during processing and use, which accelerates oxidative degradation when heated. The thermal oxidation of polyolefin belongs to the free radical chain reaction mechanism and has automatic catalytic behavior, which can be divided into three steps: initiation, growth and termination. The chain fracture caused by hydroperoxide group leads to the reduction of molecular weight, and the main products of homolytic cleavage are alcohols, aldehydes, ketones, and finally oxidized into carboxylic acids. Carboxylic acid plays an important role in catalytic oxidation of metals. 2. When plastic molding is processed, the colorant is decomposed and discolored because it is not resistant to high temperature The pigments or dyes used for plastic coloring have a temperature limit, and when this limit temperature is reached, the pigments or dyes will undergo chemical changes and generate various low molecular weight compounds, and the reaction formulas are more complex; Different pigments have different reactions and products, and the temperature resistance of different pigments can be measured by weight loss analysis. · Colorant reacts with resin to cause color change The reaction of colorant and resin is mainly manifested in some pigments or dyes and resins during processing and molding, and these chemical reactions will lead to changes in hue and degradation of polymers, thus changing the performance of products. 1. Reduction reaction Certain polymers, such as nylon and amino plastics, are strong acid reducing agents in the molten state, which can reduce and fade pigments or dyes that are stable at processing temperatures. 2. Alkali exchange The alkali earth metals in the polyvinyl chloride emulsion polymer or some stabilized polypropylene can undergo "alkali exchange" with the alkali earth metals in the colorant, thus changing the color from blue-red to orange. PVC emulsion polymer is VC in the emulsifier (such as sodium dodecyl sulfonate C12H25SO3Na) aqueous solution by stirring polymerization method, the reaction contains Na+; In order to improve the heat resistant oxygen performance of PP, antioxidants such as 1010 and DLTDP are often added. Antioxidant 1010 is a transesterification reaction of 3,5 di-tert-butyl-4-monohydroxypropionate methyl ester and sodium pentaerythritol catalyzed, while DLTDP is a reaction of Na2S aqueous solution with acrylonitrile to prepare dipropionic thiodipropionic acid, which is hydrolyzed to thiodipropionic acid. Finally, the product is esterified by lauryl alcohol, and the reaction also contains Na+. During the molding process of plastic products, the residual Na+ in the resin will react with the lake pigment containing metal ions such as C.I.PGment ·Red48:2(BBC or 2BP) :XCa2++2Na+ +Ca2+ 3. Reaction between pigment and hydrogen halide (HX) PVC removes HCI when the temperature rises to 170℃ or under the action of light to form conjugate double bonds. Halogenated flame retardant polyolefin or colored flame retardant plastic products are also dehalogenated HX in high temperature molding. (1) The reaction between ultramarine and HX Ultramarine pigment widely used for coloring or eliminating yellow light in plastics. It is a sulfur-containing compound. (2) Copper and gold powder pigments accelerate the oxidation and decomposition of PVC resin Copper pigment can be oxidized to Cu+ and Cu2+ at high temperature, which will accelerate the decomposition of PVC. (3) The destruction of metal ions on polymers Some pigments have destructive effect on polymer, such as manganese deposit pigment C.I.P. igmentRed48:4 is not suitable for PP plastic product molding, the reason is that the varivalent metal manganese ion catalyzes the decomposition of hydroperoxide through electron transfer in the thermal oxidation or photooxidation of PP, leading to the accelerated aging of PP. The ester bond in polycarbonate is easy to be hydrolyzed and decomposed by alkali when heated, and it is easier to promote decomposition once metal ions are present in the pigment. Metal ions also promote the thermal oxygen decomposition of resins such as PVC and cause color changes. To sum up, when producing plastic products, we should avoid the use of color pigments that react with resins is the most feasible and effective way. · Reactions between colorants and auxiliaries 1, the reaction between sulfur pigments and auxiliaries Sulfur-containing pigments, such as cadmium yellow (the solid solution of CdS and CdSe), should not be used for PVC due to poor acid resistance, and should not be used with lead additives. 2. Lead compounds react with sulfur stabilizer The lead component in chrome yellow pigments or molybdenum chrome red reacts with antioxidants such as thiodistearate DSTDP. 3. Reaction between pigment and antioxidant Resin with antioxidants, such as PP, some pigments and antioxidants will also react, thus weakening the function of antioxidants, so that the thermal oxygen stability of the resin deteriorates. For example, phenolic antioxidants are easily absorbed by or react with carbon black and lose their activity; In white or light-colored plastic products, phenolic antioxidants form phenolic aromatic complexes with titanium ions to make the products yellow. We can prevent the color change of white pigment (TiO2) by selecting suitable antioxidants or adding auxiliary additives, such as zinc antacid salt (zinc stearate) or P2 phosphite ester. 4. Reaction between pigment and light stabilizer The action of pigments and light stabilizers, in addition to the reaction between sulfur-containing pigments and nickel-containing light stabilizers described above, will generally reduce the effectiveness of light stabilizers, especially blocked the effect of amine light stabilizers and azo yellow and red pigments, its light stability decline effect is more obvious, not as stable as the uncolored, this phenomenon has no exact explanation. · Reactions between auxiliaries If many auxiliaries are used improperly, unexpected reactions may occur and make the product color change. For example, flame retardant Sb2O3 reacts with sulfur-containing resistance to produce Sb2S3: Sb2O3+ -- S -- →Sb2S3+ -- O -- Therefore, when considering the production formula, the additives must be carefully selected. · Color change caused by automatic oxidation of additives The automatic oxidation of phenolic stabilizers is an important factor in promoting the color change of white or light-colored products, which is often called "Pinking" (red) in foreign countries. It is conjugated by oxidation products such as BHT antioxidants (2-6-di-tert-butyl-4-methylphenol) and is shaped like a 3,3 ',5,5 'monostilbenone reddish reaction product. This discoloration occurs only in the presence of oxygen and water and no light. Exposed to ultraviolet light, the reddish stilbenone rapidly decomposes into a yellow monocyclic product. · Color pigments cause color change under the action of light and heat Some colored pigments under the action of light and heat, molecular configuration tautomerism, such as the use of C.I.Pig.R2(BBC) pigment from azo type to quinone type, change the original conjugation effect, resulting in the reduction of conjugation bonds, resulting in color from dark blue red to light orange red. At the same time, under the catalytic action of light, it decomposes with water, which changes the co-crystalline water and causes fading. · Color change caused by atmospheric pollutants When plastic products are stored or used, some reactive groups, whether resins or additives, or coloring pigments, under the action of light and heat, will interact with atmospheric moisture or chemical pollutants such as acids and bases, causing a variety of complex chemical reactions, which will lead to fading or discoloration over time. This situation can be avoided or mitigated by adding appropriate thermal oxygen stabilizer, light stabilizer, or selecting high-quality weather resistant additives and pigments.

Connected particles are a series of particles connected to each other, that is, in some cases, the particles are connected by the membrane end to end or in a tangential manner. During the processing process, several process problems alone or together may cause this phenomenon to occur. For example, the processing water is too hot is a cause of the particle, in this case, the water temperature should be lowered to give sufficient quenching of the particle surface; In addition, the water flow speed is too low is also a cause of granulation, it will cause the particle cutting chamber speed slowed down, and then the particle agglomeration. In addition, if the hole distance of the die head is too close, the export expansion will cause particle contact during processing, and the solution is to replace the existing die head with a large spacing and a small number of holes. Trailing problem The so-called tail is that the edge of the particle is somewhat prominent, the cut edge is like a hockey stick shape, it looks like a pollutant or tear at the bottom of the cut. The reason for this is that the cutting device has not been able to make a clean cut here. In general, the correct cut particle coming out of the line pelletizer should be a right Angle cylinder, and the correct cut particle coming out of the underwater pelletizer should be a nearly perfect spherical shape. Usually, materials that are not prone to fining will also produce fining due to tailing. Assuming that all machining parameters have been checked, tailing can generally be diagnosed as a cutting problem. For the line cutting line, the solution is to replace the hob and bottom knife to provide a new and sharp cutting edge; Or re-determine the equipment spacing according to the values specified in the manufacturer's manual. For underwater grits, the template and blade need to be checked to ensure that there are no nicks, as nicks and grooves often cause tailing. Material waste problem For many crystalline materials, such as general-purpose polystyrene, fining appears to be a common and specific hazard. They become a problem for processors because they can change the bulk density of the material, degrade or burn in the extruder barrel, and cause problems for the transportation process. The main goal of the resin manufacturer is to produce a uniform grain shape, that is, with a given length and diameter, without contamination from material residues or foreign substances. To solve this problem, the purpose of reducing the powder can be achieved by adjusting the equipment and controlling some important process parameters. When entering the cutter, the temperature of the wire line should be as close as possible to the Veka softening point of the material to ensure that the wire is subjected to as much heat as possible, thus avoiding breakage. For a particular polymer, selecting a hob with the right cutting Angle plays an important role in reducing the amount of material. For unfilled polymers, Stellite alloy steel or tool steel hobs should be used as much as possible, and the edge of the hob and base knife should be kept sharp to avoid breaking the polymer. For the subsequent equipment after cutting, whether pressurized or vacuum equipment, it is necessary to avoid wrapping air. For the underwater graining line, it is necessary to ensure that sufficient knife pressure against the die surface is maintained during the processing process, and the residence time after graining is properly adjusted to ensure that the particles are hot when entering the dryer. Bottom knife rupture problem The base knife of the granulator is a hard, carbonized steel sheet with Invar alloy welded in place to enable it to be threaded into the support. In general, the bottom knife breaks when the blade of the bottom knife is turned, and appropriate measures can be taken to avoid this problem by carefully following the recommended methods in the manufacturer's equipment manual. Here, it is particularly important to emphasize that the threaded Invar mandrel is fixed in place by silver welding, which has a shear limit and is prone to being destroyed by excessive torque during installation. In addition, during rotation or installation, the cracked bottom knife is prone to shift and will fly in the granulator, damaging the blade of the hob and increasing maintenance costs. Shrinkage gap problem Shrinking voids and hollow particles indicate improper tempering of wire material. The shrinkage gap may be only a small pit on the particle end surface in mild cases, and in severe cases it may produce hollow particles, like a mixstick. This phenomenon occurs when the core temperature of the wire is close to a molten state and the wire shrinks immediately after it is cut. When the wire is properly tempered, the temperature gradient at the interface remains constant, and it does not respond to the cooling medium (air or water) when it is cut. The specific reason for the shrinkage gap is that when the processing water is too cold for a particular polymer, the outer surface of the wire material freezes, creating a hard shell, and trapping heat in the core of the wire material. In addition, the wire does not have enough time to soak in air or water, resulting in the heat of the wire core cannot be transferred to the wire surface, so that good cross-section cooling cannot be performed. Particles produced by underwater pelleting, due to the presence of trapped volatiles in the melt, will also appear to shrink voids, an effective preventive measure is to check the vacuum hole on the extruder. Line drift problem Linear drift is the tendency of linear material to cluster to one side on the feeding platform, which will cause the quality of the grain to deteriorate, there are slender strips and processing disorders. If the cutting plane of the grain cutter is not parallel to the extruder extrusion template, the line material will tend to be crowded to the left or right, and eventually lead to the line material drift. In addition, other causes of line drift include the gap between the lower feed roller and the scraper is not constant, the diameter of the lower feed roller is inconsistent, etc. Wire control problem The long strip is an abnormal product produced by the grain cutter. As the name suggests, its length is longer than the regular particle size, and the size of the long strip usually varies within a few inches. The appearance of thin strips (also known as bevel cutting particles) indicates that the wire attitude is not well controlled when the wire is fed into the hob, specifically because the wire is not at a vertical Angle when fed into the hob, so the end of the wire will appear at a slant Angle when cutting. The distance between the feed roll (bite point) and the hob (cut point) is called the press distance, and there is nothing to control the wire material at this span. The grain cutter is different from the wood planer, if the feeding roller is not properly installed, or the working condition is poor, then the plastic wire will not be fed into the cutting device at an Angle perpendicular to the cutting surface, so that the wire material begins to cross each other, causing further deterioration of the cutting quality, and eventually causing serious problems. The crossed wire material will force the two feeding rolls apart from each other, causing the wire to lose tension, which in turn causes the wire to temporarily drop, causing the wire material to be biased to both sides of the feeding roll. An early warning sign of these problems is that the upper feed roller is in poor condition, with grooves, cracks, or discoloration (hardening due to aging or heat). Other common problems with wire control include: lower feed roller wear, which causes loss of traction; Incorrect wire quenching process, which will cause the wire to bend like a snake; There is also a worn wire template, which will produce a variety of wire with different diameters. Not only that, manufacturers are also wary of extremely worn hobs and bottom knives that hold the wire to the cutting point, because the bottom knife is responsible for pushing the wire to the cutting point and preventing the cutter from operating at ultra-high speeds, which can cause the wire to sway. In the underwater pelleting system, the main reason for the production of slender strips is that the feed speed does not match the cutter speed, in this case, it is necessary to increase the cutter speed to match the feed speed, or reduce the feed speed to match the cutter speed. In addition, during the processing, it is necessary to ensure that there are enough blades on the cutting head to ensure that the particles have the correct geometry, and to check whether there is a slow movement or obstruction of the polymerized material flow in the die hole.

Polymer materials include plastics, rubber, fibers, films, adhesives and coatings. Because they have many potential properties better than traditional structural materials, they are used more and more widely in the field of military and civilian products. However, in the process of processing, storage and use, due to the combined effect of light, heat, oxygen, water, high-energy radiation, chemical and biological erosion and other internal and external factors, the chemical composition and structure of polymer materials will undergo a series of changes, physical properties will also change accordingly, such as hard, sticky, brittle, discoloration, loss of strength, etc., this phenomenon is the aging of polymer materials. The essence of aging of polymer materials refers to the change of physical structure or chemical structure, which is manifested as the gradual decline in the performance of the material and the loss of its due use value. Aging failure of polymer materials has become one of the key problems that limit the further development and application of polymer materials. Aging phenomenon Due to the different varieties of polymer materials and different conditions of use, there are different aging phenomena and characteristics. For example, agricultural plastic film after the sun and rain occur discoloration, brittleness, transparency decline; Aviation plexiglass after use for a long time silver pattern, transparency decline; The elasticity of rubber products decreases, hardens, cracks or becomes soft and sticky after long-term use; Paint after long-term use, loss of light, powder, bubble, peeling, etc. The aging phenomenon can be summarized in the following four changes: 1. Appearance changes Stains, spots, silvers, cracks, frosting, powdering, stickiness, warping, fisheye, wrinkling, shrinking, scorching, optical distortion, and optical color changes occur. 2. Physical properties change Including solubility, swelling, rheological properties and cold resistance, heat resistance, water permeability, air permeability and other performance changes. 3, mechanical properties change Tensile strength, bending strength, shear strength, impact strength, relative elongation, stress relaxation and other properties change. 4, electrical performance changes Such as surface resistance, volume resistance, dielectric constant, breakdown strength and other changes. Aging factor The physical properties of polymer materials are closely related to their chemical structure and aggregation state structure. The chemical structure is a long chain structure of macromolecules connected by covalent bonds, and the aggregation structure is a spatial structure of many macromolecules arranged and piled up by intermolecular force, such as crystalline, amorphous, crystal-amorphous. The intermolecular forces that maintain the aggregate structure include ionic bond force, metallic bond force, covalent bond force and van der Waals force. Environmental factors will lead to the change of intermolecular forces, even the break of the chain or the fall off of some groups, which will eventually destroy the aggregate structure of the material and change the physical properties of the material. There are usually two factors that affect the aging of polymer materials: internal factors and external factors. Intrinsic factor 1. Chemical structure of polymer The aging of polymers is closely related to their chemical structure, and the weak bond of the chemical structure is easily affected by external factors to break and become free radicals. This free radical is the starting point of radical reactions. 2. Physical form Some of the molecular bonds of the polymer are ordered and some are disordered. The ordered molecular bonds can form crystalline regions, and the disordered molecular bonds are amorphous regions. The shape of many polymers is not uniform, but semi-crystalline, with both crystalline and amorphous regions. The aging reaction begins from the amorphous region. 3, three-dimensional integration The stereointegration of polymer is closely related to its crystallinity. In general, structured polymers have better aging resistance than random polymers. 4, molecular weight and its distribution In general, the molecular weight of the polymer has little relationship with aging, and the distribution of molecular weight has a great impact on the aging performance of the polymer, the wider the distribution, the easier it is to age, because the wider the distribution, the more end groups, the easier it is to cause aging reaction. 5, trace metal impurities and other impurities When the polymer is processed, it is necessary to contact with the metal, and it may be mixed with trace metals, or in the polymerization, some metal catalysts remain, which will affect the initiation of automatic oxidation (that is, aging). External factor 1. The influence of temperature When the temperature increases, the movement of polymer chains intensifies. Once the dissociation energy of chemical bonds is exceeded, it will cause thermal degradation of polymer chains or group shedding. At present, thermal degradation of polymer materials has been extensively reported. The decrease of temperature often affects the mechanical properties of materials. The critical temperature points closely related to mechanical properties include glass transition temperature, viscous flow temperature and melting point. The physical state of the material can be divided into glassy state, high elastic state and viscous flow state. 2, the influence of humidity The influence of humidity on polymer materials can be attributed to the swelling and dissolution of water on the material, so that the intermolecular forces that maintain the aggregation structure of polymer materials change, thus destroying the aggregation state of the material. Especially for non-crosslinked amorphous polymers, the influence of humidity is extremely obvious, which will cause the swelling and even the aggregation state disintegration of polymer materials, thus damaging the performance of the material. For the crystalline form of plastics or fibers, the effect of humidity is not very obvious due to the existence of water penetration limitations. 3. The effect of oxygen Oxygen is the main cause of aging of polymer materials. Due to the permeability of oxygen, crystalline polymer is more resistant to oxidation than amorphous polymer. Oxygen first attacks the weak links on the polymer main chain, such as double bonds, hydroxyl, hydrogen and other groups or atoms on the tertiary carbon atom, forming polymer peroxyradicals or peroxides, and then causes the break of the main chain in this part. In severe cases, the molecular weight of the polymer decreases significantly, the glass transition temperature decreases, and the polymer becomes viscous. In the presence of some initiators or transition metals that are easily decomposed into free radicals, the oxidation reaction tends to be intensified. 4, light aging Whether the polymer is irradiated by light can cause the fracture of molecular chain depends on the relative size of light energy and dissociation energy and the sensitivity of polymer chemical structure to light wave. Due to the existence of the ozone layer and the atmosphere on the earth's surface, the wavelength range of solar light that can reach the ground is 290 ~ 4300nm, and the light wave energy is greater than the dissociation energy of chemical bonds only in the ultraviolet region, which will cause the fracture of polymer chemical bonds. For example, the ultraviolet wavelength of 300 ~ 400nm can be absorbed by polymers containing carbonyl groups and double bonds, and the macromolecular chain is broken, the chemical structure is changed, and the material properties are deteriorated; Polyethylene terephthalate has strong absorption of 280nm UV, and the degradation products are mainly CO, H and CH. Polyolefin containing only C-C bonds has no UV absorption, but in the presence of a small amount of impurities, such as carbonyl groups, unsaturated bonds, hydroperoxide groups, catalyst residues, aromatics and transition metal elements, it can promote the photooxidation reaction of polyolefin. 5, the influence of chemical media The chemical medium can only play a role if it penetrates into the interior of the polymer material, and these roles include the role of covalent bonds and the role of secondary bonds. The action of covalent bond is manifested as chain breaking, crosslinking, addition or the combination of these effects, which is an irreversible chemical process. Although the destruction of the secondary valence bond by the chemical medium does not cause the change of chemical structure, the aggregate structure of the material will change, and its physical properties will change accordingly. Environmental stress cracking, dissolution cracking, plasticizing and other physical changes are typical manifestations of chemical aging of polymer materials. The method of eliminating dissolution cracking is to eliminate the internal stress of the material, and annealing after the molding of the material is conducive to eliminating the internal stress of the material. Plasticizing is in the case of continuous contact between the liquid medium and the polymer material, the interaction between the polymer and the small molecule medium partly replaces the interaction between the polymer, so that the polymer chain segment is easier to move, which is manifested as the glass transition temperature is reduced, the strength, hardness and elastic modulus of the material is decreased, and the elongation at break is increased. 6. Biological aging Since plastic products almost all use a variety of additives in the processing process, they often become a nutrient source of mold. When mold grows, it absorbs the nutrients on the surface and inside of the plastic and becomes mycelium, which is also a conductor, so that the insulation of the plastic is reduced, the weight changes, and the severe peel will occur. The metabolites of mold growth contain organic acids and toxins, which will make the surface of the plastic sticky, discoloration, brittleness, and reduced finish, and will also cause long-term contact with this mouldy plastic. Polysaccharide natural polymers and their modified compounds can be processed into degradable disposable films, sheets, containers, foaming products, etc. by means of blending modification with general plastics. The waste can be gradually hydrolyzed into small molecular compounds by the intervention of amylase and other polysaccharide natural polymer decomposition enzymes widely existing in the natural environment. And eventually break down into pollution-free carbon dioxide and water and return to the biosphere. Based on these advantages, the polysaccharide natural polymer compounds represented by starch are still an important part of degradable plastics.

There are many kinds of adhesives, which can be divided into many kinds according to composition, use and physical form. Here, the classification and use of adhesives from these three aspects are sorted out, hoping to help you. 01 Classification by composition 1, silicone adhesive It is a kind of sealing adhesive, with cold resistance, heat resistance, aging resistance, waterproof, moisture-proof, high tensile fatigue strength, small permanent deformation, non-toxic and so on. In recent years, such adhesives have developed rapidly in China, but at present, the raw materials of silicone adhesives in China rely on imports. 2, polyurethane adhesive It can bond a variety of materials, and can maintain the physical and chemical properties of materials at low or ultra-low temperatures after bonding, mainly used in footwear, packaging, automobiles, magnetic recording materials and other fields. 3, polyacrylic resin It is mainly used in the production of pressure sensitive adhesives, and is also used in the textile and construction fields. Adhesive for construction: mainly used for construction decoration, sealing or bonding between structures. 4, hot melt adhesive According to different raw materials, it can be divided into EVA hot melt adhesive, polyamide hot melt adhesive, polyester hot melt adhesive, polyolefin hot melt adhesive and so on. At present, the main domestic production and use of EVA hot melt adhesive. The main raw materials of polyolefin adhesives are ethylene series, SBS and SIS copolymers. 5, epoxy resin adhesive It can be used for bonding between metal and most non-metallic materials, and is widely used in construction, automobiles, electronics, electrical appliances and daily household goods 6. Urea-formaldehyde resin, phenolic aldehyde, melamine-formaldehyde adhesive Mainly used in the wood processing industry, the amount of formaldehyde released after use is higher than the international standard. Adhesives for wood processing: Used for MDF, plasterboard, plywood and particleboard 7, synthetic adhesive Mainly used in wood processing, construction, decoration, automobile, shoemaking, packaging, textile, electronics, printing and binding and other fields. At present, China imports nearly 200,000 tons of synthetic adhesives every year, including hot melt adhesives, silicone sealing adhesives, polyacrylic adhesives, polyurethane adhesives, automotive PVC plastic adhesives and so on. At the same time, about 20,000 tons of synthetic adhesives are exported every year, mainly polyvinyl acetate, polyvinyl formaldehyde and pressure sensitive adhesives. ‍ 02 Classification by use 1, sealing adhesive It is mainly used for the connection of doors, Windows and prefabricated houses. The high-grade sealing adhesives are silicone and polyurethane adhesives, and the intermediate ones are neoprene rubber adhesives and polyacrylic acids. In China, the construction adhesive market, silicone adhesives, polyurethane sealing adhesives should be the direction of future development, the current account for about 30% of the sales of building sealing adhesives. 2. Adhesive for building structure It is mainly used for joining between structural units. For example, the external repair of reinforced concrete structures, metal reinforcement fixing and construction site construction, epoxy resin series adhesives are generally considered. 3, automotive adhesive It is divided into 4 kinds, namely, adhesive for car body, interior decoration, windshield and chassis of car body. At present, the annual consumption of automotive adhesives in China is about 40,000 tons, of which the largest use is PVC plastic adhesives, neoprene rubber adhesives and asphalt series adhesives. 4. Adhesive for packaging It is mainly used to make pressure sensitive tape and pressure sensitive label, and glue the surface of paper, plastic, metal and other packaging materials. The adhesive used for the packaging material of paper is polyvinyl acetate emulsion. Adhesives for plastic and metal packaging materials are polyacrylic acid emulsions, VAE emulsions, polyurethane adhesives and cyanoacrylate adhesives. 5, electronic adhesive Less consumption, currently less than 10,000 tons per year, most of them are used for integrated circuits and electronic products, and are mainly used epoxy resins, unsaturated polyester resins, silicone adhesives. We can supply the sealing adhesives for 5 micron thick electronic components by ourselves, but the adhesives for 3 micron thick electronic components need to be imported from abroad. 6. Adhesive for shoe making The annual consumption is about 125,000 tons, of which 110,000 tons are needed for neoprene adhesives and about 15,000 tons for polyurethane adhesives. Because neoprene rubber adhesives need to use benzene as a solvent, and benzene is harmful to the human body, the development should be limited, in order to meet the development needs of the footwear industry, the use of polyurethane series adhesives will be the direction. 03 Classified by physical form 1. Paste sealant This kind of sealant is basically used in static joints, and the use period is generally 2 years or more. Three main materials are usually used: oil and resin, polybutylene, asphalt. 2. Liquid elastomer sealant Such sealants include liquid polymers that are vulcanized to form a truly elastic state and have the ability to withstand repeated joint deformation. Polymer elastomers used in elastomer sealants include liquid polysulfide rubber, thioterminal polypropylene ether, liquid polyurethane, room temperature vulcanized silicone rubber and low molecular weight butyl rubber. This type of sealant is usually combined into two components, and the two components are mixed when used. 3. Hot melt sealant Hot melt sealant is also called hot construction sealant. It refers to a sealant based on elastomer and thermoplastic resin admixture. This type of sealant is usually extruded directly into the joint by a certain mouth model under heating (150 ~ 200 ° C). Thermal construction can improve the wetting ability of the sealant to the bonded base material, so it has good adhesion to most of the bonded base material. Once placed in the appropriate position, it is cooled to form or film, becoming a strong elastic body with little shrinkage. The main materials of hot construction sealant are isobutylene polymer, EPDM rubber and thermoplastic styrene block copolymer. They are usually blended with thermoplastic resins such as EVA, EEA, polyethylene, polyamide, polyester, etc. 4. Liquid sealant This kind of sealant is mainly used for sealing the mechanical joint, to replace the solid sealing material, namely the solid washer, to prevent the leakage of the internal fluid of the machinery from the joint. This kind of sealant is usually made of polymer materials such as rubber, resin and so on as the main material, and then with fillers and other components. Liquid sealant is usually divided into four categories: non-dry adhesive type, semi-dry viscoelastic type, dry adhesion type and dry stripping type. Select according to the specific parts and requirements.

Warping deformation is one of the common defects in the injection molding of thin shell plastic parts, because it involves the accurate prediction of the amount of warping deformation, and the warping deformation law of different materials and different shapes of injection parts is very different. When the amount of warping deformation exceeds the allowable error, it becomes a forming defect, and then affects the product assembly. Accurate prediction of warpage deformation of various kinds of increasing thin-walled parts (wall thickness less than 2mm) is the premise of effective control of warpage defects. The warping deformation analysis mostly adopts qualitative analysis, and measures are taken from product design, mold design and injection molding process conditions to avoid large warping deformation as far as possible. Cause analysis Mold aspect The position, form and number of gates of the injection mold will affect the filling state of the plastic in the mold cavity, resulting in deformation of the plastic part. The longer the flow distance, the greater the internal stress caused by the flow and feeding between the frozen layer and the central flow layer. On the contrary, the shorter the flow distance, the shorter the flow time from the gate to the flow end of the part, the thinner the frozen layer thickness during mold filling, the lower the internal stress, and the warpage deformation will be greatly reduced. If only one center gate or one side gate is used, because the shrinkage rate in the diameter direction is greater than the shrinkage rate in the circumference direction, the molded plastic part will be distorted and deformed; Warping deformation can be effectively prevented by using multi-point gate. When the point casting molding, also due to the anisotrophicity of plastic shrinkage, the location and number of the gate have a great impact on the degree of deformation of the plastic parts. Because the use of 30% glass fiber reinforced PA6, and the obtained weight is 4.95kg of large injection parts, so there are many reinforcing ribs along the flow direction of the surrounding wall. Full balance is achieved for each gate. In addition, the use of multiple gates can also shorten the flow ratio of plastics (L/t), so that the material density in the mold cavity is more uniform and the shrinkage is more uniform. At the same time, the whole plastic part can be filled with less injection pressure. The smaller injection pressure can reduce the molecular orientation of the plastic, reduce its internal stress, and thus reduce the deformation of the plastic parts. Mold temperature: Mold temperature has a great influence on the internal performance and apparent quality of the product. The mold temperature depends on whether the plastic is crystalline, the size and structure of the product, the performance requirements, and other process conditions (melt temperature, injection speed and injection pressure, molding cycle, etc.). Pressure control: The pressure in the injection molding process includes two kinds of plasticizing pressure and injection pressure, and directly affects the plasticization and product quality of plastics The study of warping deformation of plastic products by experimental method is mainly reflected in the study of material properties, product geometry and size, injection molding process conditions on the influence of warping deformation of products. A large number of experiments have been designed to obtain the influence of gate geometry, holding pressure parameters (holding pressure and holding time) and mold elasticity on the final size of the product. The warping properties of plates with different materials and wall thickness were studied by using PET as a polymer base. The relationship between reinforcement ratio, anisotropy of linear thermal expansion coefficient, product thickness and warpage of 33% glass reinforced fiber PA66 injection molded disk was studied experimentally. The concept of warpage index was proposed for the first time and the warpage characteristics of PA66 plastic products were studied by using the warpage index. The relationship between warp index, warp and fiber orientation, and the relationship between yield and warp index are also studied. Experimental research on warping deformation is often limited to a specific geometric shape, a specific material and process conditions, and can not fully consider the influence of many factors on warping deformation, and can not predict the size of possible warping deformation in the product design stage. In actual use, the limitations of the empirical formula are also obvious, not only affected by experimental conditions, but also related to many factors such as the processing method of experimental data and the application conditions of the empirical formula, and an empirical formula is only applicable to the production process that is quite close to the experimental situation. Shrinkage/warping Since warping deformation is related to non-uniform shrinkage, the relationship between shrinkage and warping is analyzed by studying the shrinkage behavior of different plastics under different process conditions. Based on the simulation of injection molding flow, pressure holding and cooling, a model for predicting the shrinkage of injection molding products is put forward through experiment and linear regression method. It is difficult to obtain products with high dimensional accuracy with high shrinkage materials, and strive for high precision, amorphous resins and resins with consistent shrinkage in all directions should be applied as far as possible. Many materials can measure the shrinkage of products under the conditions of changing flow speed, holding pressure, holding time, mold temperature, filling time, product thickness and other parameters. According to the test results, the shrinkage of the product is divided into three parts: volume shrinkage, non-uniform shrinkage caused by molecular orientation and non-uniform shrinkage caused by unbalanced cooling. Shrinkage prediction methods for volume shrinkage, crystal content, mold limitation, plastic orientation, etc., use flow and cooling analysis results to predict shrinkage strain. Cooling system design During the injection process, the uneven cooling rate of the plastic part will also form the uneven shrinkage of the plastic part, and this contraction difference leads to the generation of bending torque and the bending of the plastic part. If the temperature difference between the mold cavity and the core used in the injection molding of flat plastic parts is too large, the melt close to the cold mold cavity will soon cool down, and the material layer close to the hot mold cavity will continue to shrink, and the uneven shrinkage will warp the plastic parts. Therefore, the cooling of the injection mold should pay attention to the temperature of the cavity and the core, and the temperature difference between the two should not be too large. In addition to considering the temperature of the internal and external surfaces of the plastic parts tends to be balanced, the temperature on each side of the plastic parts should also be considered to be consistent, that is, when the mold is cooled, the temperature of the cavity and the core should be kept uniform as far as possible, so that the cooling speed of the plastic parts is balanced, so that the contraction of the parts is more uniform, and the deformation is effectively prevented. Therefore, the layout of cooling water holes on the mold is very important. After the distance between the tube wall and the cavity surface is determined, the distance between the cooling water holes should be as small as possible to ensure the uniform temperature of the cavity wall. At the same time, because the temperature of the cooling medium rises with the increase of the length of the cooling channel, the mold cavity and core have a temperature difference along the water channel. Therefore, the length of each cooling loop is required to be less than 2m. Several cooling circuits should be set up in the large mold, and the inlet of one loop is located near the outlet of the other loop. For the long plastic parts, the cooling circuit should be used to reduce the length of the cooling circuit, that is, to reduce the temperature difference of the mold, so as to ensure uniform cooling of the plastic parts. The design of ejector system also directly affects the deformation of plastic parts. If the ejecting system layout is not balanced, it will cause the imbalance of the ejecting force and cause the deformation of the plastic parts. Therefore, the ejector system should be designed to balance with the stripping resistance. In addition, the cross-sectional area of the ejector rod can not be too small to prevent the unit area of the plastic parts from being stressed too much (especially when the demoulding temperature is too high) and the plastic parts from deformation. The arrangement of the ejector rod should be as close as possible to the part with large demoulding resistance. Under the premise of not affecting the quality of plastic parts (including the use of requirements, dimensional accuracy and appearance, etc.), as much as possible should be set up to reduce the overall deformation of plastic parts. When soft plastics are used to produce large deep-cavity thin-walled plastic parts, due to the larger demoulding resistance and the softer material, if a single mechanical ejection method is completely used, the plastic parts will be deformed, and even the top through or folding will cause the plastic parts to be scrapped, such as the use of multiple parts combined or gas (liquid) pressure and mechanical ejection will be better. Effect of residual thermal stress on warping deformation of products In the process of injection molding, residual thermal stress is an important factor causing warping deformation, and has a great influence on the quality of injection molding products. Because the influence of residual thermal stress on product warping deformation is very complicated, mold designers can use injection molding CAE software to analyze and predict. During the molding process, due to the uneven orientation and shrinkage, the internal stress of the plastic melt is uneven, so the product warps and deforms after the mold is produced under the action of the uneven internal stress. Therefore, many scholars analyze and calculate the internal stress and warping of products from the perspective of mechanics. In some foreign literatures, warping is regarded as the residual stress caused by non-uniform shrinkage. During the cooling phase of injection molding, when the temperature is higher than the glass transition temperature, the plastic is a viscoelastic fluid with stress relaxation: when the temperature is lower than the glass transition temperature, the plastic becomes solid. The liquid-solid phase transition and stress relaxation in the cooling process of plastics have great influence on the accurate prediction of residual stress and residual deformation of products. Phase transition and stress relaxation behavior of plastic from liquid to solid during cooling phase. For the uncured region, the viscous behavior of the plastic is described by the viscous fluid model. For the cured region, the viscoelastic behavior is described by the standard linear solid model. The viscoelastic phase transition model and the two-dimensional finite element method are used to predict the thermal residual stress and the corresponding warping deformation. Influence of plasticizing stage on warping deformation of product In the plasticizing stage, the glassy particles are converted to a viscous fluid state, providing the melt required for mold filling. In this process, the temperature difference between the axial and radial (relative to the screw) of the polymer will cause stress in the plastic; In addition, the injection pressure, speed and other parameters of the injection machine will greatly affect the degree of molecular orientation during filling, and then cause warping deformation. Low speed is used in the initial stage of injection, high speed is used in cavity filling, and low speed injection is used when filling is near the end. Through the control and adjustment of the injection speed, the appearance of the product can be prevented and improved, such as rough edges, jet marks, silver bars or coke marks and other undesirable phenomena. The multi-stage injection control program can reasonably set the multi-stage injection pressure, injection speed, pressure holding pressure and melting mode according to the structure of the flow channel, the form of the gate and the structure of the injection part, which is conducive to improving the plasticizing effect, improving product quality, reducing the defect rate and extending the life of the mold/machine. By controlling the oil pressure, screw position and screw speed of the injection molding machine by multistage program, the appearance of the molded parts can be improved, the corresponding measures of shrinking, warping and burring can be improved, and the size of the molded parts injected by each mold can be reduced. By controlling the oil pressure, screw position and screw speed of the injection molding machine by multistage program, the appearance of the molded parts can be improved, the corresponding measures of shrinking, warping and burring can be improved, and the size of the molded parts injected by each mold can be reduced. Effect of filling and cooling stage on warping deformation of product The molten plastic is filled into the mold cavity under the action of injection pressure, and the process of cooling and solidification in the mold cavity is the key link of injection molding. In this process, temperature, pressure and speed interact with each other, which has a great impact on the quality and production efficiency of plastic parts. Higher pressures and flow rates produce high shear rates, which cause differences in molecular orientation parallel to and perpendicular to the flow direction, while creating a "freezing effect". "Freezing effect" will produce freezing stress, forming the internal stress of plastic parts. The influence of temperature on warping deformation is reflected in the following aspects. A. The temperature difference between the upper and lower surfaces of plastic parts will cause thermal stress and thermal deformation; B. The temperature difference between different areas of plastic parts will cause uneven shrinkage between different areas; C. Different temperature states will affect the shrinkage rate of plastic parts. Influence of demoulding stage on warping deformation of Plastic Products Plastic parts are mostly glassy polymers when they are removed from the cavity and cooled to room temperature. It is easy to deform the product because of unbalance of demoulding force, uneven movement of ejecting mechanism or improper ejecting area. At the same time, the stress frozen in the plastic part during the mold filling and cooling stage will be released in the form of deformation due to the loss of external constraints, resulting in warping deformation. True three-dimensional method to calculate residual stress and final shape (shrinkage and warping). They took into account the effect of the holding stage, divided the product into three layers, and analyzed the residual stress and deformation by a three-dimensional grid. A numerical simulation model of residual stress and deformation caused after the holding stage is presented. The thermal viscoelastic model (including volume relaxation) was used to calculate the residual stress. The finite element method is based on the shell theory composed of planar elements, which is suitable for thin-walled injection molded products with complex shapes. Injection products shrinkage on the influence of warping deformation solution The direct cause of warping deformation of injection molded products is the uneven shrinkage of plastic parts. If the influence of shrinkage during the filling process is not considered in the mold design stage, the geometry of the product will be very different from the design requirements, and serious deformation will cause the product to be scrapped. In addition to the deformation caused by the filling stage, the temperature difference between the upper and lower walls of the mold will also cause the difference in the shrinkage of the upper and lower surfaces of the plastic parts, resulting in warping deformation. For warping analysis, the contraction itself is not important, but the difference in contraction is important. In the process of injection molding, due to the arrangement of polymer molecules along the flow direction, the shrinkage rate of the plastic in the flow direction is larger than that in the vertical direction, which causes the warping deformation of the injection part. Generally, uniform shrinkage only causes changes in the volume of plastic parts, and only uneven shrinkage will cause warping deformation. The difference between the shrinkage rate of crystalline plastics in the flow direction and the vertical direction is larger than that of amorphous plastics, and the shrinkage rate of crystalline plastics is also larger than that of amorphous plastics, and the superposition of the shrinkage rate of crystalline plastics and the anisotropy of shrinkage leads to the warping tendency of crystalline plastic parts is much larger than that of amorphous plastics. The multi-stage injection molding process selected on the basis of the geometric shape analysis of the product: because the cavity of the product is deeper and the wall is thinner, the mold cavity forms a long and narrow flow channel, and the melt must pass quickly when flowing through this part, otherwise it is easy to cool and solidified, which will lead to the danger of filling the mold cavity, and high-speed injection should be set here. However, high-speed injection will bring a lot of kinetic energy to the melt, and a great inertial impact will be generated when the melt flows to the end, resulting in energy loss and overflow phenomenon. At this time, it is necessary to slow down the flow rate of the melt and reduce the mold filling pressure, and maintain the commonly called pressure holding pressure (secondary pressure, subsequent pressure) to supplement the melt shrinkage into the mold cavity before the melt solidify at the gate. This puts forward the requirement of multi-stage injection speed and pressure in the injection molding process. Solution of warping deformation caused by residual thermal stress The velocity of the fluid surface should be constant. Rapid injection should be used to prevent melt freezing during injection. The injection speed should be set to allow for rapid filling in critical areas (such as flow channels) while slowing down at the inlet. The injection speed should ensure that the die cavity is stopped immediately after filling to prevent overfilling, flash and residual stress.

Injection molded nylon and glass fiber are generally raw materials modified with glass fiber. It has good rigidity and is the leader of rigid raw materials. Then we often encounter a phenomenon, what if the rigidity of the high material impact resistance is poor? Impact strength is also known as impact strength, that is, impact strength. The size of this information indicates the flexibility of the data. However, stiffness and flexibility are two relative information contents. Stiffness increases, ductility decreases. But there is something else. In the case of injection molding pure polyester and glass fiber, the rigidity and impact strength will be improved to a certain extent, usually on the basis of pure polyester. So, what can we do to further increase the impact strength? In other words, plasticity needs to be improved, so a certain proportion of toughening agents must be added. People often use thermal polymerization of Poe and EPDM (ethylallene monomer). In order to have better ductility, we only need to add a certain amount of toughening agent. Another way is to further divide the glass fiber, because the glass fiber has a variety of properties and a large price difference. In order to better improve the impact strength, when injection molding nylon and glass fiber as a formula, you can consider better performance of glass fiber. This kind of glass fiber is like a raw material in the construction of steel bars, with a supporting role. Excellent building reinforcement performance is bound to pull the overall performance, including impact strength. If we want to further improve it, we must make further adjustments from a macro perspective. The size and distribution of glass fiber are the reasons that affect the impact strength of nylon and glass fiber injection molding raw materials. This is mainly from the production and processing of the screw, we must pay attention to the screw order of the extruder. The longer the length of the glass fiber, the more complex the glass fiber, and the impact strength will be improved to a certain extent. This is also an assumption for injection molding under some polyester feedstock conditions. If the raw material has a good foundation and the impact strength itself is at a certain relative height, it is likely to further increase the impact strength. Although the pure raw materials of domestic manufacturers have their own advantages, the comprehensive performance belongs to middle and low grade products. The difficulty factor is difficult to further improve, and it needs to become the pillar of imported raw materials. In the initial stage of product development, imported raw materials are mainly of special types. For example, a certain type and size of raw material can be used as a commodity. Without modifying the material, it can meet the requirements of the specification and complete mass production.

Chemical blowing agent Chemical blowing agent is also known as decomposable blowing agent. They can be uniformly dispersed in the resin, decomposed by heat, and can produce at least one gas. Can be divided into inorganic blowing agent and organic blowing agent two categories. Organic blowing agents are the main blowing agents used in plastics, mainly azo, nitroso and sulfonyl hydrazides. There are also some blowing agent components whose foaming gas is released through an endothermic reaction between the two components. 01 azodicarbonamide Orange crystalline powder, relative molecular weight 116.1, relative density 1.65, fineness (200 mesh passage) ≥99.5%, moisture ≤0.1%, ash ≤0.1%. Soluble in alkali, insoluble in alcohol, gasoline, benzene, pyridine and other general organic solvents, difficult to dissolve in water. Decomposition temperature 190 ~ 205℃, non-flammable. The gas output is 200 ~ 300ml/g, mainly nitrogen, carbon monoxide and a small amount of carbon dioxide. The storage is stable at room temperature and has self-extinguishing, but it produces a large amount of gas when it is decomposed above 120 ° C and is prone to explosion in a closed container. Application: Suitable for PE, PVC, PS, PP, ABS, etc. The decomposition products are non-toxic, odorless and non-polluting, and pure white foam can be prepared. The decomposition temperature of this product is high, and the bubbles produced are uniform and dense. Suitable for closed cell foam, atmospheric or pressurized foam, thick or thin foam and other foam products. Such as PVC and plasticized paste foam, polyolefin calendering and molding foam, foamed artificial leather and so on. 02 2,2 '-azodiisobutyronitrile White crystalline powder, relative density 1.1, volatile 1%, methanol insoluble 0.1%, melting point >99℃. Soluble in methanol, ethanol, propanol, ether, petroleum ether and other organic solvents, insoluble in water. The decomposition temperature is 98 ~ 110℃, the nitrogen is released, and the gas output is 130 ~ 155ml/g. Slow decomposition at room temperature, 30℃ storage for several months after significant deterioration, so this product should be stored below 10℃. Application: Especially suitable for PVC, also can be used in epoxy resin, PS, phenolic resin and rubber. Decomposition heat is low, about 125.6 ~ 167.5J/mol, so the use of up to 40% does not cause products to burn, can be made white products. This product has low decomposition temperature and can be used for ordinary PVC paste. The toxicity is high, which greatly limits its application. In recent years, its application as blowing agent has been gradually reduced, and it is mainly used as polymerization initiator. 03 Diisopropyl azodicarboxylate Orange oily liquid, relative molecular mass 202, freezing point 2.4℃, boiling point 75.5℃(33.31Pa), when heated alone, still stable at 240℃. Heat stabilizers such as lead salts, organotin compounds, cadmium soap and zinc soap can be used to activate it and reduce the decomposition temperature. The gas output at 100 ~ 200℃ is 200 ~ 350ml/g. Soluble in common plasticizers. Use: liquid blowing agent, suitable for PE, PP, PVC and so on. It is easy to disperse in plastics, the bubble structure is uniform and dense, the decomposition products are odorless, non-toxic, colorless, and non-polluting, and can produce foam with extremely light color. Closed-cell foam or open-cell foam can be prepared by adjusting the formula and processing conditions. 04 Barium azodicarboxylate Bright yellow powder, relative molecular weight 253.37, relative density 1.67, decomposition temperature 240 ~ 250℃. Gas capacity 170 ~ 175ml/g, decomposition to produce nitrogen, carbon monoxide, carbon dioxide, barium carbonate, etc. Insoluble in common solvents. Use: high temperature blowing agent. High decomposition temperature, good processing safety. Suitable for polymers with high softening points, especially PP. It also has good effect as a blowing agent for injection molding and extrusion molding of nylon resin. It can also be used for hard and semi-hard PVC, ABS, etc. 05 Diethyl azobarboxylate A red, odorless oily liquid. Molecular weight 174.16. Decomposition temperature 110 ~ 120℃. Gas output 190ml/g. Soluble in plasticizer. Stable storage. No response to vulcanization accelerator. Sensitive to moisture and pH changes. Metal salts (Cu, Fe, Co, Pb, Al, Sn and other metals) facilitate decomposition. Use: PVC and its copolymer, PE, polyester, epoxy resin, PS, rubber blowing agent. The dosage is 0.5 ~ 10%. 06 azo-aminobenzene Yellowish brown crystal with special smell. Relative molecular weight 197.24. Melting point 96 ~ 98℃, decomposition temperature 150℃. Gas output 113ml/g. Stable storage. It is easy to crystallize from the surface of the product, decompose at a lower temperature in the acidic medium, and belongs to the polluting blowing agent. Application: It can be used as blowing agent of PVC and its copolymer, PS, PE, phenolic resin, epoxy resin, raw rubber and rubber, silicone polymer. Dosage 0.1 ~ 5%. 07 N, N-dinitroso pentamethylene tetramine (blowing agent H) Light yellow crystalline powder, odorless in itself, in the wet state has a formaldehyde smell. Molecular weight 186.18. Relative density: 1.45. Solubility (room temperature, g/100g solvent) : methyl ethyl ketone 1.6, pyridine 1.8, ethyl acetoacetate 2.6, acetonitrile 5.6, morpholine 2.0, 1-nitropropane 1.4, dimethylformamide 14.7. The solubility in water, ethanol, benzene, ether and acetone is about 1. Decomposition temperature 190 ~ 205℃ (in the air), 130 ~ 190℃ (in resin or using decomposition AIDS). Gas volume 260 ~ 270ml/g. The decomposition gas is mainly nitrogen, with a small amount of carbon monoxide and carbon dioxide. This product is flammable, and contact with acid or acid mist will quickly catch fire and burn, so it can not be stored together with these substances, and open flame should be strictly prohibited. Uses: As a blowing agent used in PVC. Large gas volume, high foaming efficiency. The use of organic acids such as salicylic acid, adipic acid, phthalic acid or urea as foaming AIDS can reduce the decomposition temperature (usually adjusted at 90 ~ 130 ° C). The heat generated during decomposition is large, which is easy to cause the "core burning" of thick products, and the decomposition products have a foul odor. The odor can be eliminated by using urea. The amount of this product in PVC is about 7 ~ 15%. 08 N,N' -dimethyl-n,N' -dinitroso p-phthalamide The active ingredient in commercial products is 70%. Yellow powder, relative molecular weight 250.21, relative density 1.2. The decomposition temperature in the air is 105℃, 90 ~ 105℃ in the resin, the gas output is 126ml/g, and the decomposition gas is mainly nitrogen. The pure product is explosive, sensitive to impact and friction, so the product is filled with inert filler to increase safety. Use: Can be used as PVC blowing agent, especially suitable for PVC paste, without the use of foaming additives can make open and closed cell foam body. Decomposition heat is small, can be used for thick products, decomposition residue pollution-free, but in the plastic will spray frost. 09 Sulfonyl hydrazides - benzene sulfonyl hydrazides Light yellow or white fine powder, relative molecular weight 172.20. The relative density is 1.43 ~ 1.48, and the melting point is 99℃. The decomposition temperature in the air is >95℃, and the decomposition temperature in plastics is 95 ~ 100℃. The gas output is 130ml/g, and the decomposition gas is mainly nitrogen, with a small amount of water vapor. Application: Can be used for PVC, phenolic resin, polyester blowing agent. The decomposition process is accompanied by heat, which increases the internal temperature of the product, so it is best to mix with sodium bicarbonate. The sulfur compounds produced by the decomposition of this product have a bad smell. 10 p-toluenesulfonizide White crystalline fine powder. Molecular mass 186. Relative density 1.40 ~ 1.42. Melting point 100 ~ 110℃. Soluble in alkali, soluble in methanol, ethanol, methyl ethyl ketone, slightly soluble in water, aldehyde, insoluble in benzene and toluene. The decomposition temperature is 100 ~ 110℃, nitrogen and a small amount of water are released, and the gas output is 110 ~ 125ml/g. Sulfonic acid is hydrolyzed in hot water and nitrogen is released. At normal temperature, there is no moisture absorption phenomenon, and its chemical properties are stable. This product is flammable substance, but will not catch fire in case of acid. Usage: This product is a low temperature blowing agent, suitable for PVC and other plastics and rubber. The resulting gases and decomposition residues are non-toxic, odorless and non-polluting. The cell structure produced by this product is fine and uniform, the shrinkage rate of the product is small, the tearing strength is large, especially suitable for the manufacture of closed cell foam and sponge. This product can be used for PVC white foam body, but in this case the mold surface must be chrome plated. Due to the low decomposition temperature of this product, the temperature should be avoided during kneading processing (generally lower than 80 ° C) to prevent advance foaming. Foaming AIDS can be used without this product. This product cannot be used with blowing agent H, because the reaction of these two blowing agents produces a lot of heat, which can lead to the internal burning of the product. This product should not be used with lead salt, so as not to produce black lead sulfide precipitation. 11 4,4 '-diphenyl sulfonyl hydrazine oxide White or light yellow crystalline powder. Molecular weight 358.39. The relative density is 1.52. The decomposition temperature is 140 ~ 160℃, nitrogen and water vapor are released, and the gas output is about 120ml/g. Soluble in cyclohexanone, ethylene glycol, ether, slightly soluble in ethanol and warm water, insoluble in benzene and gasoline. Uses: This product is a very wide range of adaptability blowing agent, known as universal blowing agent. It can be used for PVC, PE, PP, ABS resin, etc., and can also be used as a blend of plastic and rubber and a foaming agent of various synthetic rubber. Although the structure contains ether bonds, it is very stable. The decomposition temperature in the resin is 120 ~ 140℃. Sodium bicarbonate can be used to activate it and reduce the decomposition temperature. The cell structure is fine and uniform, and the decomposition gas and residue are non-toxic, odorless and non-polluting products. Suitable for the manufacture of PE foamed wire and cable insulation materials, microporous PVC paste foam and other foam plastics. This product has high processing safety, and there is no risk of premature foaming within 100℃. However, this product releases water when decomposing foaming, so it is not suitable for water avoidance occasions. 12 3,3 '-disulfonyl hydrazine diphenyl sulfone Grayish white powder. Relative molecular mass 406.45. The relative density is 1.60. The decomposition temperature in the air is 148 ° C, and the decomposition temperature in vinyl plastics is 135 ~ 145 ° C. Gas output 110ml/g. Non-toxic. Usage: This product is mainly used as soft PVC blowing agent, can also be used for hard PVC and PE. The gas generated by decomposition during foaming has no odor and is non-toxic, but the residue is polluting and can make the product colored. 13 1, 3-phenyldisulfonyl hydrazine The commercial form is a mixture of 50% of this product and 50% chlorinated paraffin, which is a paste containing grayish white fine particles, with a relative molecular weight of 266.29 and a relative density of 1.5. The decomposition temperature in the air is about 150 ° C, the decomposition temperature in plastics is 115 ~ 130 ° C, and the gas output is 300ml/g. Usage: This product can be used as blowing agent for rubber and plastic, mainly used for rubber. High processing safety, the risk of early foaming is small. Alkaline substances reduce their decomposition temperature. The gas produced by decomposition is mainly nitrogen. 14 p-toluenesulfonamide Fine white powder. Molecular weight 229.25. Soluble in dimethyl sulfoxide, dimethyl formamide, dimethyl acetamide, concentrated ammonium hydroxide and alkaline water, insoluble in acetic acid, acetone, carbon tetrachloride, ethylene glycol, isopropyl alcohol, petroleum ether, toluene and water. The decomposition temperature in the air is 230 ° C, and the decomposition temperature in plastics is 213 ~ 225 ° C. The gases emitted are mainly nitrogen and carbon dioxide (about 2:1). The solid residues after decomposition are mainly p-xylene disulfide and p-toluenesulfonate, the former soluble in benzene and the latter soluble in water. This product has good storage stability at room temperature, but it should be avoided near steam pipes, fire sources and direct sunlight. Use: This product is a high temperature nitrogen blowing agent, especially suitable for high temperature processing of plastics, such as ABS resin, nylon, hard PVC, HDPE, PP, PC, etc. Good processing safety, no risk of advance foaming. This product can also be used for natural rubber and synthetic rubber foam. 15 4,4 '-oxobide This product is a high temperature blowing agent, the decomposition temperature is 210 ~ 220℃, the gas volume is about 145ml/g. The gases emitted are mainly nitrogen and carbon dioxide. Application: Suitable for hard PVC, HDPE, high softening point PP, PC, ABS resin and other plastics with high processing temperature. 16 Trihydrazyl triazine White or off-white powder. Molecular weight 171.61. Decomposition temperature 235 ~ 275℃. The gas volume is about 247ml/g. The gases emitted are mainly nitrogen and carbon dioxide. Usage: This product is a high temperature blowing agent, suitable for hard and semi-hard PVC, PP, PC, ABS resin, polyamide and other plastics with high processing temperature. Good processing safety. 17 5-phenyltetrazole A liquid substance. The relative density is 1.105 (50℃). Usage: This product is a high temperature blowing agent, suitable for PC, polyamide and other polymers with high melting temperature. 18 Polysiloxane-polyalkoxy ether copolymer Yellow or brownish yellow oily thick transparent liquid. Acid value <0.2mgKOH/g. The relative density is 1.04 ~ 1.08. Viscosity 0.15 ~ 0.5Pa· s (50℃).

Physical blowing agent Physical blowing agent is mainly through the change of the physical state of blowing agent to form the bubble hole in the plastic. The ideal physical blowing agent should have the following conditions: ① Inert, non-toxic; ② Compatible with resin; ③ The diffusion rate in the resin matrix is small; ④ When the resin reaction emits heat, or when placed to external heating should be easy to volatilize. Generally, physical blowing agents are divided into three categories: (1) compressed gas; ② Soluble solid; ③ Volatile liquid with boiling point below 0℃. In the process, when the pressure is eliminated, the compressed gas expands, or the liquid is expanded by heat evaporation, or the dissolved soluble solid substance sublimates to produce a gas. There are many types of physical blowing agents, such as aliphatic hydrocarbons containing 5 to 7 carbons, chlorofluorocarbons, chlorofluorocarbons and carbon dioxide gases, since the 1950s, fluoro-trichloromethane (CFC-11) as the preferred foaming agent of polyurethane is widely used, because of its destructive effect on the atmospheric ozone layer, in order to protect the ecological environment of the earth, it is necessary to prohibit the use of CFCS compounds. Over the years at home and abroad have been looking for and develop the ideal alternative products, alternative blowing agent in addition to considering the nature of the blowing agent itself, generally also need to polyether polyols, foaming agent, catalyst and other raw materials for appropriate adjustment and improvement, so that the formula system to achieve optimization, so the key to physical blowing agent lies in the development and application of alternative products. So far, there are mainly four alternatives to blowing agent CFC-11. (1) Carbon dioxide blowing agent There are two types of carbon dioxide blowing agents, one is the reaction of isocyanate and water to produce carbon dioxide (water foam) as blowing agent, and the other is liquid carbon dioxide. Compared with CFC-11, the advantage of water foaming is that carbon dioxide ODP(ozone loss value) is zero, non-toxic, safe, no recycling problems, no need to invest in upgrading foaming equipment; The disadvantage is that the viscosity of polyol components is higher in the foaming process, the foaming pressure and foam temperature are higher, and the adhesion between foam and the substrate is poor, especially the thermal conductivity of hard foam products is high. Because carbon dioxide diffuses faster from the bubble hole, and air enters the bubble hole slowly, thus affecting the dimensional stability of the foam, although it can be improved by modification, it is still not as good as CFC-11 foam material. At present, carbon dioxide blowing agent is mainly used in heating pipeline insulation, packaging foam and agricultural foam and other fields with low insulation requirements. The advantages and disadvantages of liquid carbon dioxide foam are the same as that of water foam, which is mainly used for polyurethane soft foam at present, and can be used for hard foam to overcome the shortcomings of water foam, such as increased consumption of isocyanate, brittle foam and poor adhesion to the substrate. However, the liquid foaming machine needs to be improved, and the storage and transportation cost of liquid carbon dioxide increases. At present, the liquid carbon dioxide foaming technology is still under continuous research and development. (2) hydrochlorofluorocarbon blowing agent Hydrogenated chlorofluorocarbons (HCFC) blowing agents, which contain hydrogen in their molecules, are chemically unstable and easier to break down, so their ODP is much smaller than that of CFC-11, so HCFC is used as a first-generation replacement for CFC blowing agents for temporary use during the transition period and should be replaced by chlorine-free compounds as soon as possible. At present, the European Union, the United States and Japan have banned the use of HCFC blowing agents, and the deadline for use in China is 2030. At present, the most mature product that can replace CFC-11 commercially is HCFC-14LB, which has a good compatibility with polyols and isocyanates, and can directly replace CFC-11 with HCFC-14LB without adding equipment, and the dosage is less than CFC-11 when the foam with the same density and similar physical characteristics is achieved. The drawbacks of HCFC-141B are that the raw material price is higher, it is soluble to some ABS and high-impact polystyrene, and its thermal conductivity is higher than that of CFC-11, so the resulting foam density is higher to achieve insulation effect. Another HCFC replacement for CFC-11 is the 60:40 HCFC-22/HCFC-14LB mixture, which is the most commonly used solvent in industrial production and has mature production technology and is affordable. The disadvantage is that the HCFC-22/HCFC-141B system has a relatively low solubility in general polyols. Processing polyols containing HCFC-22 is relatively difficult. In addition, HCFC-124 has an ODP value of only 1/5 of HCFC-141B, allowing for a longer service life, and some foreign companies plan to use it in construction and refrigerator appliance foam to compete with higher-cost hydrogenated fluoroalkanes (HFC). (3) hydrocarbon blowing agent The hydrocarbons used for polyurethane foaming agents are mainly cyclopentane, especially the rigid foam system of cyclopentane has the advantages of low thermal conductivity, anti-aging performance, and zero ODP value, and is often used in the fields of refrigerators, cold storage and building insulation and insulation, and has become the first choice for hard foam CFC-11 substitutes in China. In addition, with n-butane and isobutane as auxiliary foaming agents, the following two problems must be solved in the preparation of cyclopentane polyurethane rigid foam, explosion-proof equipment should be used to solve the problem of cyclopentane inflammability and explosive; Some measures such as n-pentane, isopentane and cyclopentane used together can improve the foam fluidity, so as to solve the problem of poor solubility of cyclopentane in polyether polyols. (4) hydrogenated fluoroalkane (HFC) blowing agent Hfc-type compounds with ODP value of zero are ideal substitutes for CFC-11 in the production of soft PU foam. The early HFC-type blowing agents are mainly HFC-134A and HFC-152A, which have low molecular weight and low boiling point, and the dosage is less than that of CFC-11 when the foam with the same density and similar physical properties is reached. And the performance is relatively stable, but their defect is that the thermal conductivity is relatively high, and the solubility in the general polyol is low, the processing of the combined polyether containing HFC-134A and HFC-152A is relatively difficult, and the foaming equipment is needed to meet the processing requirements. Because of the shortcomings of these two products, people have accelerated the research and development of new HFC-type blowing agents. Research and development show that HFC-245FA and FC-365MFC have great potential. These two products and CFC-11 have similar characteristics, thermal conductivity and HCFC-141B in the same range, its ODP value is zero, extremely low toxicity, good dimensional stability, HFC-245FA electrical insulation performance is excellent, the disadvantage is low boiling point; HFC-365MFC has a high boiling point but is flammable.

This time we went to the province to participate in an industry high-end exhibition! Although there is hard work, pay, of course, there are a lot of harvest! However, all the hard work, is very worthwhile!

First, the production workshop The layout of the production workshop is mainly considered from two aspects: to meet the production needs, optimize the layout according to the production process, and meet the requirements of flexible energy use under specific production conditions. 1, the power supply, in order to meet the stable production of power required at the same time with an appropriate margin, not too much surplus caused by excessive non-functional consumption. 2. Build efficient cooling water circulation facilities, and equip the cooling water system with effective insulation and insulation system. 3, optimize the overall production layout of the workshop. Many production processes have the coordination, reasonable coordination can reduce the time required for turnover and energy consumption, improve production efficiency. 4, lighting and other plant equipment as far as possible to consider the most effective small unit control. 5, the workshop equipment to do regular maintenance, to avoid damage to public facilities, affecting the normal operation of production, resulting in increased energy consumption. Second, injection molding machine Injection molding machine is a large energy consumer in the injection molding workshop, and the energy consumption is mainly two parts: motor and heating. 1, choose the right injection molding machine according to the characteristics of the product. "Big horse car" type injection molding often means a lot of energy waste. 2, the selection of all-electric injection molding machine and hybrid injection molding machine, with excellent energy saving effect, can save 20-80%. 3, the use of new heating technology, such as electromagnetic induction heating, infrared heating, etc., can achieve 20-70% heating energy saving. 4, for heating and cooling system using effective insulation measures to reduce heat and cold losses. 5, keep the equipment transmission parts good lubrication, reduce the increase in energy consumption due to increased friction or unstable equipment operation. 6, the selection of low compression hydraulic oil, reduce the hydraulic system work energy waste. 7, the use of parallel action, multi-cavity injection molding, multi-component injection molding and other processing technology can significantly save energy. 8, the traditional mechanical hydraulic injection molding machine also has a variety of energy-saving drive systems, instead of the traditional quantitative pump mechanical hydraulic injection molding machine energy-saving effect is significant. 9. Regular maintenance of heating and cooling pipes to ensure that no impurities, scale blockage and other phenomena occur inside the pipes to achieve the designed heating and cooling efficiency. 10. Ensure that the injection molding machine is in good working condition. Unstable processing can lead to defective products and increase energy consumption. 11, ensure that the equipment used is suitable for the processed products, such as PVC processing often need to use special screws. Third, injection mold Mold structure and mold condition often have a significant impact on injection molding cycle and processing energy consumption. 1, reasonable mold design, including runner design, gate form, cavity number, heating and cooling water channels, etc., all help to reduce energy consumption. 2, the use of hot runner mold, not only can save materials, reduce material recovery energy consumption, the molding process itself also has significant energy saving effect. 3, copying fast cooling fast hot mold can significantly save processing energy consumption, and achieve better surface quality. 4, to ensure that the cavity balanced filling, help shorten the molding cycle, to ensure product quality uniformity, has excellent energy saving effect. 5. The use of CAE-assisted design technology for mold design, mold flow analysis and simulation can reduce the energy consumption of mold debugging and multiple mold repairs. 6, under the premise of ensuring product quality, the use of lower clamping force molding, help to extend the life of the mold, conducive to the rapid filling of the mold, help save energy. 7, do mold maintenance work to ensure effective heating and cooling water channel conditions. Fourth, peripheral equipment 1, choose the appropriate ability of the auxiliary equipment, both to meet the requirements of the work, but not too rich. 2, do equipment maintenance, to ensure that the equipment is in normal working condition. Auxiliary equipment that is not working normally will cause instability in production and even poor quality of parts, resulting in increased energy consumption. 3, optimize the cooperation and operation sequence of the host and peripheral equipment. 4. Optimize the mutual position of peripheral equipment and production equipment, and make peripheral equipment as close to the host as possible without affecting the operating conditions. 5, many auxiliary equipment manufacturers provide on-demand energy supply systems, can achieve significant energy savings. 6, the use of rapid mold change equipment to reduce the waiting time required to switch products in production. fifth,Materials The energy consumption of different materials is different, and the poor management of materials or the improper management of recycled materials will lead to increased production energy consumption. 1, under the premise of meeting the performance of the product, the material with lower processing energy consumption should be preferred. 2, under the condition of satisfying the performance and cost optimization, give priority to the selection of high-fluidity materials. 3, note that different suppliers of materials may have different process conditions. 4, material drying treatment, it is best to use with drying, to avoid material moisture waste energy after drying. 5, do a good job of material preservation, to prevent materials mixed with impurities or foreign bodies, ultimately resulting in poor products. 6. Some products are allowed to add certain recycled materials, but attention should be paid to the preservation and cleanliness of recycled materials to avoid bad parts due to unclean materials. Six, processing technology 1, under the premise of meeting the performance of the product, the shortest molding cycle is used. 2, if there is no special factors, as far as possible to use the supplier recommended processing technology for processing. 3, for specific products and molds, all stable equipment and process parameters are saved to shorten the next replacement production time. 4, optimize the process, using low clamping force, short cooling time and pressure holding time. Seventh,Adopt new technologies 1, the use of auxiliary molding technology, such as gas assisted, liquid assisted, steam assisted, micro-foam injection molding technology. 2, the use of unit molding scheme to reduce intermediate links. 3. Adopt new technologies such as in-mold welding, in-mold spraying, in-mold assembly and in-mold decoration. 4, the use of new low pressure molding technology, shorten the molding cycle, while reducing the melt temperature. 5. Energy regeneration system is adopted. Eighth, Production management 1, one-time production of high-quality products, reducing the defective rate is the largest energy saving. 2, the maintenance of the entire production system is closely related to energy consumption. This not only involves the main machine, but also surrounding and factory equipment, for example, if the workshop die changing crane fails, manpower is needed to change the mold, which is bound to extend the waiting time of the equipment, resulting in increased energy consumption of the equipment. 3, equipped with workshop energy consumption monitoring system, easy for enterprises to purposefully implement energy analysis and improvement. 4, when the equipment is shut down for maintenance, not only check the maintenance content and projects of the equipment itself, but also pay attention to the status of the connection between the equipment and other systems, and whether the working performance is reliable. 5, regularly compare with industry benchmarks to see if there is room for further improvement. 6, the establishment of reliable contracts and cooperative relations with suppliers is beneficial to the energy conservation management of enterprises.

Glass fibre Glass fiber is often used in engineering plastics filler, its main components are silica, and other derived metal oxides, the current international mainstream production process for the pool kiln wire drawing method; According to the amount of alkali content in glass, it can be divided into alkali-free glass fiber, medium alkali glass fiber and high alkali glass fiber; The glass fiber commonly used in engineering plastics is mainly alkali free cut glass fiber and non-twist long glass fiber. After adding glass fiber, engineering plastics will have the following changes. Advantages: 1, enhance rigidity and hardness, the increase of glass fiber can improve the strength and rigidity of plastics; 2, improve the heat resistance and thermal deformation temperature, taking nylon as an example, increase the nylon glass fiber, thermal deformation temperature increased at least 30 degrees above, the general glass fiber reinforced nylon temperature can reach 220 degrees above; 3, improve dimensional stability, reduce shrinkage; 4, reduce warping deformation; 5, reduce creep; 6, reduce moisture absorption. Cons: When the modulus of the product increases, the toughness will decrease. It has an adverse effect on the flame retardant performance, because the candle wick effect will interfere with the flame retardant system and affect the flame retardant effect; The exposure of glass fiber will reduce the gloss of the surface of plastic products. The length of the glass fiber directly affects the brittleness of the material; If the glass fiber is not treated well, the staple fiber will reduce the impact strength; Good treatment of the filament will increase the impact strength. In order to make the material brittle will not decrease greatly, it is necessary to choose a certain length of glass fiber. The fiber content of the product is also a key issue. The industry generally adopts 15%, 25%, 30%, 50% and other integer content, and the specific need to determine the content of glass fiber according to the use of the product. In order to obtain good mechanical properties and surface effects, the diameter and length of the glass fiber selection and subsequent modification of the surface treatment, glass fiber content, etc., are crucial! Calcium carbonate Calcium carbonate products are divided into heavy calcium carbonate and light calcium carbonate. Heavy calcium carbonate is referred to as heavy calcium, and the English abbreviation is GCC, which is made by directly crushing natural calcite, limestone, white and shell by mechanical method. Because the sedimentation volume of heavy calcium carbonate is smaller than that of light calcium carbonate, it is called heavy calcium carbonate. At present, there are two main processes for industrial production of heavy calcium carbonate, one is dry method and the other is wet method. The dry process can produce products at lower cost and with a wide range of uses compared to the wet process. Light calcium carbonate is referred to as light calcium, also known as precipitated calcium carbonate, English abbreviation PCC, is the raw materials such as limestone forging to produce lime mainly composed of calcium oxide and carbon dioxide, and then add water to digest lime to produce lime milk, the main component is calcium hydroxide, and then through carbon dioxide, carbonized lime milk to produce calcium carbonate precipitation, and finally by dehydration, drying and crushing. Or, calcium carbonate is precipitated by the double decomposition reaction of sodium carbonate and calcium chloride, and then prepared by dehydration, drying and grinding. Calcium carbonate is one of the earliest inorganic fillers used to fill PP, and the application of micron calcium carbonate has been in a dominant position. The research shows that the addition of calcium carbonate can increase the impact strength of PP, but reduce the tensile strength. The addition of light calcium carbonate can improve the impact strength and yield strength at the same time, and the effect of the PCC treated with stearic acid is better, and the impact strength of the calcium carbonate treated with titanate coupling agent can significantly improve the impact strength of PP. With the appearance of nanometer calcium carbonate, it has been found that nanometer calcium carbonate can strengthen and toughen at the same time, and the toughening effect is better than micron calcium carbonate. The results show that the mechanical properties of nano-calcium carbonate composites are also very different with different morphology. Cuboidal nano-calcium carbonate is beneficial to improve the impact property of the composite, while fibrous nano-calcium carbonate can significantly improve the tensile property of the composite, nano-calcium carbonate can significantly refine PP spherulites, and promote the formation of β crystals. Glass bead Glass microbeads are a new type of silicate material, including solid and hollow. Glass beads with a particle size of 0.5-5mm are usually called fine beads, and those with a particle size below 0.4mm are called microbeads; There are a variety of microbeads according to different sources, fly ash glass microbeads are extracted from fly ash a kind of lightweight micro-spherical substance, its main component is silica, but also contains a variety of metal oxides, fly ash glass microbeads have high temperature resistance, low thermal conductivity and other advantages, used to fill plastics can not only increase the material wear resistance, pressure resistance, flame retardant and other properties, but also, Its special spherical surface can also improve the processing flow of the material, in addition, its surface gloss is good, can increase the surface gloss of the product, reduce the surface dirt adsorption. Glass microbeads are widely used to strengthen and toughen PP. The results show that the tensile modulus, bending strength and modulus of PP/ glass microbead composites increased linearly with the increase of glass microbead content, while the yield strength decreased slightly. The fracture strain increases at low content and then decreases rapidly. The impact strength of both single and twin-screw extruded materials is increased, and increases with the increase of glass microbeads in a certain range. The impact strength of single screw extruded materials is slightly higher than that of twin-screw extruded materials. Silicate mineral At present, the most widely used and studied silicate minerals are talc powder, montmorillonite, wollastonite, etc., among which attapulgite and zeolite have also received more attention. Talc and montmorillonite (MMT) are stratified silicate minerals. Talc powder is a magnesium silicate salt mineral with flake structure. Generally, the finer the particle size, the better the dispersion effect, which can improve the thermal deformation temperature and surface finish of the material. The intercalation method is often used to prepare PP composites with large spacing between MMT layers. MMT can form a good intercalation structure in PP matrix, thus improving the impact resistance and dimensional stability of PP. Attapulgite (ATP) is a chain stratified silicate. ATP is a kind of natural one-dimensional nanomaterial silicate mineral, its basic structural unit is needle or short fibrous single crystal, ATP can be combined with polypropylene at the two levels of micron filling and nano reinforcement, to improve the mechanical properties of the material. This new type of clay short fiber overcomes the disadvantages of ordinary glass fiber reinforced resin such as poor fluidity, rough appearance and serious wear to processing equipment, so it has high development value. Wollastonite is a single chain silicate mineral, usually in the form of flake, radial or fibrous aggregates. The research shows that wollastonite filled plastics can not only improve its mechanical properties, but also replace glass fiber and reduce the cost, but with the increase of the filling amount, the hardness of the composite material becomes larger, and the wear of the processing equipment is more serious. Zeolite is a frame silicate mineral. It has a rich channel structure, which can prepare functional polypropylene composite materials by adsorption or loading functional particles, and improve the added value of products. Therefore, the development of PP/ zeolite functional composite materials has great potential, and has become the focus of current research and attention. Titanium dioxide The chemical composition of titanium dioxide is titanium dioxide, according to the crystal form, there are rutile type and anatase type, rutile type is the most stable crystal form, dense structure, hardness, weather resistance and resistance to pulverization is better than anatase type, stable for various chemicals in the atmosphere, insoluble in water, good heat resistance. After titanium dioxide is added, it can not only improve the whiteness of the product, but also reduce the damage of ultraviolet light, improve the photoaging performance of polypropylene, but also improve the rigidity, hardness and wear resistance of the product, but it is poor compatibility with crystalline materials, such as PP, PA, etc., it is necessary to modify the capacity.

14, thin film fish eye Reason: Fish eyes are mainly additives in raw materials, low molecular weight resin and dust, etc., condensed on the mouth mold during processing, accumulate a certain amount after being taken away by the film, thus forming fish eyes on the film. solution ① After a certain time, increase the screw speed, increase the melt extrusion pressure, and take away the precipitates. ② Clean the mouth mold regularly. ③ Appropriately increase the melt temperature and fully plasticize.

13. The film has an odor Reason 1: the smell of the resin raw material itself; Reason 2: The extrusion temperature of the molten resin is too high, resulting in the decomposition of the resin, resulting in odor; Cause 3: The membrane bubble is not cooled enough, and the hot air in the membrane bubble is not cleared. solution ① Replace resin raw materials; ② Adjust the extrusion temperature; ③ Improve the cooling efficiency of the cooling wind ring, so that the membrane bubble is fully cooled.

12. The surface of the film is rough and uneven Reason 1: extrusion temperature is too low, the resin plasticization is poor; Reason 2: Extrusion speed is too fast. solution (1) Adjust the temperature setting of extrusion, and appropriately increase the extrusion temperature to ensure that the resin is plasticized well; ② Properly reduce the extrusion speed.

11. The membrane vesicle is unstable Reason 1: the extrusion temperature is too high, the fluidity of the molten resin is too large, the viscosity is too small, and it is easy to fluctuate; Reason 2: The extrusion temperature is too low, the discharge amount is less; Reason 3: The air volume of the cooling air ring is unstable, and the cooling of the membrane bubble is not uniform; Cause 4: The interference and influence of strong external air flow. solution ① Adjust the extrusion temperature; ② Adjust the extrusion temperature; ③ Check the cooling air ring to ensure that the air supply volume around is uniform; ④ Prevent and reduce the interference of external air flow.

10. The transverse tensile strength of the film is poor Reason 1: The cooling speed of the cooling wind ring is too slow; Reason 2: The traction speed is too fast, and the difference between the blowing ratio is too large, so that the longitudinal fibrosis is generated, and the transverse strength is worse. solution (1) Appropriately reduce the traction speed to match the blowing ratio; ② Increase the air volume of the air ring, so that the blown film is cooled quickly, and avoid high The temperature at which the elastic state is stretched is oriented.

9, the film longitudinal tensile strength is poor Reason 1: The temperature of the molten resin is too high, which will reduce the longitudinal tensile strength of the film; Reason 2: The blowing ratio is too large and does not match the traction ratio, so that the transverse orientation and tensile strength of the film are increased, and the longitudinal tensile strength will become worse; Reason 3: The traction speed is slow, and the longitudinal orientation of the film is not enough, so that the longitudinal tensile strength becomes worse. Reason 4: The cooling speed of the film is too fast; solution ① Appropriately reduce the temperature of the molten resin; ② Increase the traction speed appropriately; (3) Adjust the blowing ratio to adapt to the traction ratio; ④ Reduce the cooling speed appropriately.

8, the heat sealing performance of the film is poor Reason 1: The frost line is too low, the polymer molecules are oriented, so that the performance of the film is close to the directional film, resulting in reduced heat sealing performance; Reason 2: The blowing ratio and traction ratio are too large, and the film will have tensile orientation, which affects the heat sealing performance of the film; solution (1) Adjust the size of the air volume in the wind ring, make the dew point higher, and blow and pull under the melting point of the plastic as much as possible to reduce the molecular tensile orientation caused by blow and pull; (2) The blowing ratio and traction ratio should be appropriately small, if the blowing ratio is too large, and the traction speed is too fast, the transverse and longitudinal stretching of the film is excessive, then the performance of the film will tend to be bidirectional stretching, and the heat sealing property of the film will become worse.

7. The thickness of the film is thin Reason 1: die gap is small, the resistance is too large, so the film thickness is thin; Reason 2: The air volume of the cooling wind ring is too small, and the film cooling is too slow; Reason 3: The traction speed is too fast, the film is stretched excessively, and the thickness is thinned. solution ① Adjust the die gap; ② Increase the air volume of the air ring appropriately to speed up the cooling of the film; ③ Reduce the traction speed appropriately.