Adding a small amount of antioxidant in rubber processing can prevent or delay the aging process, so as to extend the service life of rubber and plastic products.

 

The selection of antioxidant should be based on the type and model of rubber and plastic materials, processing equipment and technological conditions, the variety and amount of other chemical additives, the use of the product environment and time limit and other factors.

 

The selection of antioxidants for industrial use should be based on the following principles.

 

Selection principle

 

compatibility

Rubber polymer and antioxidant compatibility is often poor, usually at high temperature to combine the antioxidant and polymer melt, polymer curing antioxidant molecules compatible in the middle of the polymer molecules. In the formula dosage range, the antioxidant at the processing temperature to melt. Special attention SHOULD be paid TO THE selection of solid antioxidant, light stabilizer melting point or melting range upper limit, should not be lower than the processing temperature of rubber polymer.

 

mobility

Rubber and plastic products, especially products with small surface area to volume ratio (or mass ratio), oxidation mainly occurs on the surface of the products, which requires continuous migration of antioxidants from the inside of rubber and plastic products to the surface of the products and play a role. But if the migration speed to the product surface is too fast, migration is too large, antioxidant will volatilize to the product surface environment, or diffusion agent and product surface contact in other media and loss, this loss is in fact inevitable, design formula to be considered. When THERE IS A CHOICE OF ANTIOXIDANT VARIETIES, THE VARIETIES WITH RELATIVELY LARGE MOLECULAR WEIGHTS AND APPROPRIATELY high MELTING points SHOULD BE selected, AND THE amount OF ANTIOXIDANT used should be determined based on the harshest conditions of use.

 

The stability of

Antioxidants in rubber and plastic material should be stable, in the process of using high temperature environment and less volatile loss, don't change color or no color, no decomposition (except for the processing of the thermal stability antioxidant), not an adverse chemical reactions with other additives, no corrosion of mechanical equipment, not easy extraction by other substances on the surface of the products.

 

processability

The resin viscosity and screw torque may be changed by adding antioxidants when rubber and plastic products are processed. If the difference between the melting range of antioxidant and resin is large, it will produce the phenomenon of antioxidant drift or screw inhibition. When the melting point of antioxidant is below the processing temperature of 100℃ or more, the antioxidant should be made into a certain master particle first, and then mixed with resin processing products, in order to avoid uneven distribution of antioxidant products and processing output decline due to deflection.

 

Environment and health

The antioxidant should be non-toxic or low toxic, no dust or low dust, no harmful effect on human body, no harm to animals and plants, no pollution to air, soil and water system in the processing and use of rubber and plastic products. For rubber and plastic products that indirectly or directly contact human body, such as food packaging boxes, children's toys, disposable infusion, etc., antioxidant varieties that have been tested and approved by the Food and Drug Administration (FDA) of the United States, or allowed by the Commission of the European Community law, should be selected, and the amount of added should be strictly controlled within the maximum permissible limit.

 

The main products

 

★ Antioxidant 1010

White liquid powder, melting point 120~125℃, low toxicity, is a good antioxidant. Used in PP more, is a kind of high thermal stability, very suitable for the use of high temperature conditions of auxiliaries. In addition, it can also be used for most other resins. Generally, the amount added is not more than 0.5%.

 

★ Antioxidant 1076

White or yellowish crystalline powder, melting point of 50~55℃, non-toxic, insoluble in water, soluble in benzene, acetone, ethane and esters and other solvents. It can be used as antioxidant for PE, PP, PS, PVC, PA, ABS and acrylic resins. It has the characteristics of good resistance to oxygen, small volatility and washing resistance. The general dosage is not more than 0.5%.

 

★ Antioxidant 168

White crystalline powder, melting point 183~187℃. No color, no pollution, good volatile resistance. It is an auxiliary antioxidant and has a good synergistic effect with the main antioxidant 1010 or 1076. It can be used for PE, PP, PVC, PS, PA, PC, ABS, etc.

 

★ Antioxidant CA

White crystalline powder, melting point 180~188℃, low toxicity, soluble in acetone, ethanol, toluene and ethyl acetate. Suitable for PP, PE, PVC, ABS and PA resins. The general dosage is not more than 0.5%.

 

★ Antioxidant 164

White or yellowish crystalline powder or flake. Melting point at 70℃, boiling point at 260℃ or so, non-toxic. Used in a variety of resins, widely used. More suitable for food packaging molding materials (PP, PE, PVC, ABS, polyester and PS). The general dosage is 0.01%~0.5%.

 

★ Antioxidant DNP

Light grey powder, melting point about 230℃, easily soluble in aniline and nitrobenzene, insoluble in water. Suitable for PE, PP, HIPS and ABS resin, in addition to the antioxidant efficiency, but also better thermal stability and inhibition of copper and other metals. The general dosage should not exceed 2%.

 

★ Antioxidant DLTP

White crystalline powder, melting point at about 40℃, low toxicity, insoluble in water, soluble in benzene, carbon tetrachloride, acetone. As an auxiliary antioxidant for PE, PP, ABS and PVC resins, it can change the heat resistance and oxygen resistance of products. The general dosage is 0.05%~1.5%.

 

★ Antioxidant TNP

Light yellow viscous liquid, freezing point below -5℃, boiling point above 105℃, tasteless, non-toxic, insoluble in water, soluble in acetone, ethanol, benzene and carbon tetrachloride. Suitable for PVC, PE, PP, HIPS, ABS, polyester and other resins, high temperature oxidation resistance. Use no more than 1.5%.

 

★ Antioxidant TPP

Light yellow transparent liquid, freezing point 19~24℃, boiling point 220℃, soluble in alcohol, benzene, acetone. Auxiliary antioxidant suitable for PVC, PS, PP and ABS resins. Use should not exceed 3%.

 

★ Antioxidant MB

Light yellow powder, melting point more than 285℃, soluble in ethanol, acetone, ethyl acetate, insoluble in water and benzene. Antioxidant suitable for PE, PA and PP resins; No pollution, no coloring, can be used for white or bright color products. The dosage should not exceed 0.5%.

 

★ Antioxidant 264

The appearance is white crystal. Melting point of 69 ~ 71 ℃; Density of 1.048 g/cm3 (20 ℃); Refractive index 1.4859(75℃). Soluble in methanol, ethanol, isopropanol, acetone, petroleum ether, benzene at room temperature; Insoluble in water, glycerol and propylene glycol. Odorless, tasteless, with good thermal stability. As a general phenolic antioxidant. It is widely used in polymer materials.