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Iiplastiki ezintlanu eziqhele ukusetyenziswa kwezongezo zokuguqula iiplastiki

Ixesha : 2023-04-14 14:47:57 Indawo: 22

1. Iiantioxidants

Additives whose main function is to inhibit the thermal oxidative degradation of polymer resins belong to the category of antioxidants. Antioxidants are the most important type of plastic stabilization additives, and almost all polymer resins are involved in the application of antioxidants. According to the mechanism of action, the traditional antioxidant system generally includes the main antioxidant, auxiliary antioxidant and heavy metal ion passivator.

The main antioxidant to capture polymer peroxy radicals as the main function, and "peroxy radical capture agent" and "chain termination antioxidant", involving aromatic amine compounds and hindered phenolic compounds two series of products.

Auxiliary antioxidants have the role of decomposing polymer peroxide compounds, also known as "peroxide decomposers", including thiodicarboxylic acid esters and phosphite compounds, usually used in conjunction with the main antioxidant.

Heavy metal ion passivators, commonly known as "anti-copper agent", can complex transition metal ions to prevent them from catalyzing the oxidative degradation of polymer resins, typical structures such as hydrazide compounds.

In recent years, with the polymer antioxidant theory, the classification of antioxidants has also undergone certain changes, the most prominent feature is the introduction of the concept of "carbon radical trapping agent". This radical trapping agent is different from the traditional sense of the main antioxidant, they can capture polymer alkyl radicals, equivalent to the traditional antioxidant system in the establishment of an additional line of defense.

Such stabilization additives are now reported mainly include aryl benzofuranones, bisphenol monoacrylates, hindered amines and hydroxylamines, etc., they and the main antioxidant, auxiliary antioxidants with the composition of the ternary antioxidant system can significantly improve the antioxidant stabilization effect of plastic products.

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2. Impact modifier

In a broad sense, all hard polymer products can improve the impact performance of additives are collectively referred to as impact modifiers. Impact modifiers in the traditional sense are basically based on the theory of elastic toughening, and the compounds involved almost invariably belong to a variety of copolymers and other polymers with elastic toughening effect. In the case of rigid PVC products, for example, the varieties widely used in today's application market mainly include chlorinated polyethylene (CPE), acrylate copolymers (ACR), methacrylate-butadiene-styrene copolymers (MBS), ethylene-vinyl acetate copolymers (EVA) and Acrylonitrile-butadiene-styrene copolymer (ABS), etc. EPDM used in the modification of polypropylene toughening also belongs to the scope of rubber toughening.

3. Ukubuyiswa komlilo

Most plastic products are flammable, which brings many hidden dangers to the safety of their application. To be precise, flame retardants are more appropriately called flame retardants, because "flame retardant" contains two layers of flame retardant and smoke suppression, which is a broader concept than flame retardants. However, for a long time, people have been accustomed to the concept of flame retardants, so in the literature refers to the flame retardants is actually the role of flame retardant and smoke suppression function of the general name of the additives.

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Flame retardant according to its use can be divided into additive flame retardants and reactive flame retardants. Additive flame retardants are usually added to the base resin, and they are simply physically mixed with the resin; reactive flame retardants are generally monomers containing flame retardant elements and reactive groups in the molecule, such as halogenated anhydride, halogenated biphenol and phosphorus-containing polyol, etc. Because of their reactive nature, they can be chemically bonded to the molecular chain of the resin and become part of the plastic resin, and most reactive flame retardants The structure is still the monomer of synthetic additive flame retardants.

According to the different chemical composition, flame retardants can also be divided into inorganic flame retardants and organic flame retardants. Inorganic flame retardants include aluminum hydroxide, magnesium hydroxide, antimony oxide, zinc borate and red phosphorus, etc. Organic flame retardants are mostly halogenated hydrocarbons, organic bromides, organic chlorides, phosphate esters, halogenated phosphate esters, nitrogen-based flame retardants and nitrogen-phosphorus expansion-type flame retardants. The role of smoke suppressants is to reduce the amount of smoke and the release of toxic and harmful gases of flame retardant materials, mostly molybdenum compounds, tin compounds and iron compounds. Although antimony oxide and zinc borate also have smoke suppression, but often used as a flame retardant co-effector, so it is classified as a flame retardant system.

4. Plasticizers

Plasticizers are a class of additives to increase the plasticity of polymer resins, giving products softness, and is by far the largest production and consumption of plastic additives category. Plasticizers are mainly used in PVC soft products, but also in the cellulose and other polar plastics have a wide range of applications.

Plasticizers involved in the class of compounds include phthalates, fatty dicarboxylic acid esters, trimellitic acid esters, polyesters, epoxy esters, alkyl sulfonates, phenyl phosphate esters and chlorinated paraffins, etc., especially phthalates are the most important.

5. Heat stabilizers

If not specified, heat stabilizers refer to the stabilizers used in the processing of polyvinyl chloride and vinyl chloride copolymers. Polyvinyl chloride and vinyl chloride copolymers are heat-sensitive resins, they are very easy to release hydrogen chloride when subjected to heat processing, which in turn triggers thermal aging degradation reaction. Heat stabilizers are generally used to achieve the purpose of thermal stabilization by absorbing hydrogen chloride, replacing active chlorine and double bonding addition.

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Widely used heat stabilizers in industry, including salt-based lead salts, metal soaps, organic tin, organic antimony and other main stabilizers and epoxy compounds, phosphite, polyol, a diketone and other organic auxiliary stabilizers. By the main stabilizer, auxiliary stabilizers and other additives with the composite stabilizer varieties, in the heat stabilizer market has a pivotal position.

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