Fixative
DATE：2022/8/1 8:59:11 / READ： / SOURCE：This station
Fixative
Adding stabilizer to PVC resin is mainly to prevent or alleviate the decomposition of this grease during high-temperature plasticizing processing, and it has been used after the product is formed Light and oxygen in the environment act on it, causing chemical changes, changing the performance of this product and reducing the service life of the product; In addition, adding this migration agent to the resin before processing will also reduce the difficulty of PVC resin processing molded products. Stabilizers can be classified into heat stabilizers, antioxidants and light transfer stabilizers according to their functions.2.12.3.1 heat stabilizer
Heat stabilizer is an indispensable auxiliary agent in the molding process of PVC, a heat sensitive resin. A certain proportion of heat stabilizer is added to the PVC resin before plasticization and molding to prevent the decomposition of PVC resin during the processing of high-temperature molded products.The properties and applications of common heat stabilizers are as follows. ① Tribasic lead sulfate (3PbO) has excellent heat resistance and electrical insulation, is stable to light and does not change color, but has poor compatibility and dispersion, and is toxic. It is suitable for PVC opaque products, such as soft products such as pipes, plates and artificial leather. The dosage is 0.5% - 5%. ② Dibasic lead phosphite (2PbO) has excellent thermal stability and weather resistance, but its compatibility and dispersion are poor and toxic. It is suitable for the molding of PVC opaque products, such as cable, pipe and plate. It has synergistic effect with tribasic lead sulfate and dibasic lead stearate; The dosage is 1% - 5%. ③ Dibasic lead stearate is insoluble in water and toxic. Additives suitable for PVC cable, film, artificial leather and pipe products, with thermal stability and light stability. Generally, the dosage is not more than 3%. ④ Lead stearate (PBST) has a melting point of 95~120 ℃, which is easily polluted by sulfide and toxic. It is suitable for opaque soft and hard PVC products, and the dosage is not more than 2%. ⑤ Barium stearate (BST) has a melting point of about 205 ℃. It is insoluble in water and toxic. It is suitable for soft transparent PVC board, artificial leather, hard board, pipe and other products with the dosage of 0.5% - 2%. ⑥ Cadmium stearate (cdst) has a melting point of about 100 ℃. It is insoluble in water and toxic. It is suitable for soft transparent PVC products. It is a heat and light stabilizing agent for products. The general dosage is 0.2% - 1.5%. ⑦ Calcium stearate (CAST) melting point 125~150 ℃, insoluble in water, toxic. It is suitable to be used as heat stabilizer and processing lubricant for PVC products, and the dosage is generally not more than 2.5%. ⑧ The melting point of zinc stearate (znst) is 120~130 ℃, which is insoluble in water, non-toxic, and the air mixture of dust is explosive. It is not suitable to be used alone. It is mostly used in combination with other soap salts as additives for soft PVC products. The general dosage is not more than 1%. It has the functions of thermal stability and light stability additives. ⑨ Dibutyltin dilaurate (DBTL) has a freezing point of 16~23 ℃, which is toxic. Used together with barium and cadmium salts, it is suitable for auxiliary agents for soft and transparent PVC products. It can also be used together with maleic acid and mercaptan organotin as auxiliary agents for rigid PVC products. The dosage is generally between 0.3% and 1%. ⑩ Calcium zinc liquid stabilizer has low toxicity and is suitable for use as heat stabilizer for PVC products.
2.12.3.2 antioxidant
The purpose of adding antioxidant to plastic resin is to prevent the resin from being affected by oxygen in the air (oxidative degradation) after processing high-temperature plasticized or molded products, which will change the strength, appearance and performance of plastic products, so as to shorten the service life of plastic products.The properties and uses of commonly used antioxidants are as follows. ○ 1 [b- (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester, also known as antioxidant 1010. White flowing powder, melting point 120~125 ℃, low toxicity, is a good antioxidant. It is widely used in polypropylene resin. It is a kind of additive with high heat resistance and is very suitable for high temperature conditions. It can prolong the use of products. In addition, it can also be used in most other resins. The general dosage is not more than 0.5% ② B (3,5-di-tert-butyl-4-hydroxyphenyl) octadecyl propionate, also known as anti 1076. White or yellowish crystalline powder, the melting point is 50~55 ℃, non-toxic, non-aqueous, soluble in benzene, acetone, ethane, esters and other solvents. It can be used as an agent for polyethylene, polystyrene, polyvinyl chloride, polyamide, ABS, acrylic acid and other resins. It has the characteristics of good oxygen resistance, low volatility and washing resistance. The general dosage is not 0.5%; It can be used as an auxiliary for the molding of food packaging materials. ③ 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane is also called anti ca. White crystalline powder, melting point 180~188 ℃, low toxicity, soluble in propionate alcohol, toluene and ethyl acetate. It is suitable for antioxidant additives in polypropylene, polyethylene, polyvinyl chloride, and polyamide resins, and can be used for wires and cables in contact with copper. The general dosage is not more than 0.5%. ④ 2,6-di-tert-butyl-4-methylphenol is also known as antioxidant 264. White or light yellow crystalline powder or sheet, melting point about 70 ℃, boiling point about 260 ℃, non-toxic. With a variety of resins, insoluble in water, can better inhibit oxidation, thermal decomposition and the shadow of copper, so it is widely used. It is more suitable for food packaging molding materials (PVC, polyene, polyethylene, polyester, polystyrene and ABS) resins. The general dosage is 0.01% - 0.5%. ⑤ N, n-two- β Phenyl p-phenylenediamine is also known as antioxidant DNP. Light gray powder, melting point about 230 ℃, soluble in aniline and nitrobenzene, insoluble in water. It is suitable for polyethylene, polypropylene, impact polystyrene and ABS resin. In addition to anti oxygen effect, it also has good thermal stability and inhibits the influence of copper and manganese metals. Generally, the dosage shall not exceed 2%. ⑥ Lauryl THIODIPROPIONATE is also known as antioxidant DLTP. White crystalline powder and melting point of about 40 ℃, low toxicity, insoluble in water, soluble in benzene, carbon tetrachloride, and propylene. It is used as an auxiliary antioxidant for polyethylene, polypropylene, ABS, and polyvinyl chloride resins, which can improve the heat resistance and oxygen resistance of products. The general dosage is 0.05% - 1.5%. ⑦ Trinonyl phenyl phosphite is also known as antioxidant TNP. The light yellow viscous liquid has a freezing point of less than - 5 ℃, a boiling point of more than 105 ℃, tasteless, non-toxic, insoluble in water, and soluble in acetone, ethanol, benzene and carbon tetrachloride. Suitable for PVC, polyethylene, polypropylene, impact polystyrene, ABS, polyester and other resins, with high oxidation resistance at high temperature. The usage should not exceed 1.5%. ⑧ Triphenyl phosphite is also known as antioxidant (TPP). Light yellow transparent liquid, freezing point 19~24 ℃, boiling point 220 ℃, soluble in alcohol, benzene, acetone. The auxiliary antioxidant suitable for PVC, polystyrene, polypropylene and ABS resin should be used in an amount of no more than 3%. ⑨ 2-mercaptobenzimidazole is also known as antioxidant MB. Light yellow powder, melting point >285 ℃, soluble in ethanol, acetone, ethyl acetate, insoluble in water and benzene. Antioxidant suitable for polyethylene, polyamide and polypropylene resins; This product does not pollute or stain, and can be used for white or colorful products. The dosage should not exceed 0.5%. 212.33 light stabilizer is an auxiliary agent that can delay the change of performance of plastic products under the action of light, which is called light stabilizer. The properties and uses of common light stabilizers are as follows. ① 2-hydroxy-4-n-octyloxy benzophenone, also known as UV-531. Light yellow powder, melting point about 48 ℃, soluble in acetone, benzene and ethanol, insoluble in water, with little toxicity. It has good compatibility with resin and low volatility, and can be used as light stabilizer for all kinds of plastics. The dosage should not exceed 1%. ② 2- (3', 5'- Di tert butyl-2'- hydroxyphenyl) 5 chlorobenzotriazole is also known as UV-327. Light yellow powder, melting point about 155 ℃, low toxicity, high temperature resistance, good chemical stability, good washing resistance. Suitable for alkene resin and epoxy resin. The dosage is 1% - 3%. ③ Nickel monoethyl bis (3,5-di-tert-butyl-4-hydroxybenzyl) phosphate, also known as uv-2002. Light yellow powder, melting point about 190 ℃, is a phosphorus containing nickel chelate light stabilizer in organic nickel chromium compounds. It is suitable for commonly used plastic resin molding films, and has certain anti oxygen and flame retardant effects. The dosage is not more than 1%. ④ Bis [2,2-thiobis-4 (11,3,3-tetramethyl butylphenol) nickel] is also known as am101. Quenching light stabilizer, green powder, toxic. It is suitable for polyolefin resin and molding film, and can improve processing performance, but it cannot be used in white and transparent products. ⑤ 4-benzoyl-2.2,6,6-tetramethylpiperidine is also known as uv-744. Powder makeup has a melting point of about 93 ℃, low toxicity, hydrolysis resistance, and no coloring. It is suitable for polyolefin resin, which can block the continuation of oxidation reaction and play the role of light stability.
2.12.4 auxiliary chemicals
Adding processing aids to plastic resin is mainly to improve the plasticization quality of raw materials, improve processing conditions and improve the impact resistance of products. At present, the commonly used processing aid is acrylate copolymer (ACR). For example, ACR-201 is made by copolymerization of methacrylate (MMA) and ethyl acrylate (a), which has a significant effect on promoting plasticization of raw materials; Acr-30 is made by copolymerization of MMA, EA and butyl acrylate (BA). In addition to promoting the plasticization of raw materials, it also has certain impact modification properties; Acr401, which is composed of MMA, Ba, butyl methacrylate (BMA) and ethyl methacrylate (EMA), is a processing aid with comprehensive properties.
2.12.5 impact modifier
The purpose of adding impact modifier into plastic resin is to improve the impact resistance of plastic products. Commonly used impact modifier is chlorinated polyethylene (CPE), ACR impact modifier is called MBS, EVA impact processing aids.
2.12.5.1 chlorinated polyethylene
Chlorinated polyethylene (CPE) is a commonly used impact modifier. Chlorinated polyethylene is the product of chlorination of polyethylene (the chlorine content is in the range of 34%~38%), which has good compatibility with PVC. When it is blended with PVC at the dosage of 4%~12%, its products have good low miscibility impact toughness, maintain the physical and chemical properties of PVC, and improve the weather resistance and oil resistance.
2.12.5.2 ACR impact modifier
ACR copolymer, used as impact modifier, is made of methyl methacrylate (MMA) grafted with a variety of acrylates and other active monomers. It can not only improve the impact resistance of products, but also promote the plasticization of raw materials (such as PVC). It can also improve melt fluidity, melt strength and gloss of products
2.12.5.3 MBS impact modifier
MBS is a methyl Methacrylate Butadiene Styrene copolymer, which has the same impact resistance as acr. It is applied in PVC transparent products and has good modification processing and impact resistance. Its performance is determined by the content of three components.
2.12.5.4 impact processing aids of ethylene vinyl acetate copolymer (EVA)
EVA is a kind of impact modified processing aid which has good compatibility with PVC and is often used. EVA is a polymer of rubber elastomer. Its properties are related to the content of vinyl acetate (VA) and the melt flow rate MFR. Under certain MFR conditions, the higher the VF content, the better the elastic effect, and the greater the compatibility with PVC. Note: EVA for modified rigid PVC. Its VA content shall not be less than 40%.
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