A brief introduction to commonly used rubber antioxidants.

The process by which rubber and its products gradually lose their original physical and mechanical properties during long-term storage and use due to the effects of heat, oxygen, ozone, variable metal ions, mechanical stress, light, high-energy radiation, as well as other chemical substances and mold is called aging. As the aging process progresses and develops, the performance of rubber and its products will gradually decline until they completely lose their value for use. To extend the service life of rubber products, it is necessary to incorporate substances that can inhibit the aging process into the rubber, thereby prolonging the storage period and service life of rubber and its products. These substances are called rubber antioxidants.

There are many types of rubber antioxidants with different functions. Based on their main functions, they can be divided into heat and oxygen aging inhibitors, ozone inhibitors, harmful metal ion inhibitors, fatigue inhibitors, ultraviolet absorbers, and crack resistance agents, among others. However, since each protective function is often not exclusive to a specific rubber antioxidant, most rubber antioxidants can act on several aging factors, just to varying degrees. Below is an introduction to commonly used rubber antioxidants in the wire and cable industry.

1. Rubber Antioxidant D: This product is a light gray powder, and the pure product is a white powder that is flammable. Its specific gravity is 1.18, and its melting point is not lower than 105°C. It is easily soluble in acetone, ethyl acetate, carbon disulfide, and chloroform; soluble in ethanol and carbon tetrachloride; insoluble in water and gasoline. It gradually turns gray-black in air and sunlight, but this does not affect its protective effect. Rubber Antioxidant D is a general-purpose rubber antioxidant for natural and synthetic rubber. It has good protective effects against heat, oxygen, bending cracking, and general aging factors. It has an inhibitory effect on harmful metal ions, and when used in conjunction with rubber antioxidant 4010, the resistance to heat, oxygen, bending cracking, and ozone is significantly increased. This product is easy to disperse, with a dosage of about 0.5 to 2.0 parts. Exceeding two parts will cause frosting.

2. Rubber Antioxidant RD and Rubber Antioxidant 124: Rubber Antioxidant RD and Rubber Antioxidant 124 are composed of the same chemical components, differing in that Rubber Antioxidant RD is resinous, while Rubber Antioxidant 124 is powdery. Rubber Antioxidant RD is an amber to gray-white resinous powder, non-toxic, with a softening point not lower than 74°C. Rubber Antioxidant 124 is a gray-white powder with a melting point of 114°C. Both Rubber Antioxidant RD and Rubber Antioxidant 124 are soluble in acetone, benzene, chloroform, and carbon disulfide; slightly soluble in petroleum hydrocarbons, and insoluble in water. They have some pollution potential but are not significant. They are not prone to frosting and do not affect the vulcanization process. They are flammable and non-toxic. They are suitable for natural rubber and synthetic rubbers such as styrene-butadiene and butyl rubber, with a general dosage of 0.5 to 3 parts.

3. Rubber Antioxidant MB: This product appears as a white or light yellow crystalline powder, has a bitter taste, and is non-toxic. Its specific gravity is 1.42, and its melting point is 285°C. It is soluble in ethanol, acetone, and ethyl acetate; difficult to dissolve in dichloromethane; insoluble in carbon tetrachloride, benzene, and water. It has slight pollution potential and is easy to disperse. When the dosage exceeds 2 parts, frosting may occur. When used alone, its effect is weak, and it is advisable to use it in conjunction with Rubber Antioxidant DNP for a synergistic effect. Rubber Antioxidant MB serves as a copper inhibitor, which can weaken the effect of vulcanizing agents on copper wires in rubber, significantly improving the phenomenon of copper wire turning black and rubber becoming sticky during vulcanization. Rubber Antioxidant MB can also act as a vulcanization retardant, with a general dosage of 1 to 2.5 parts.

4. Rubber Antioxidant DNP: This product is a light gray powder. The pure product is a light-colored shiny flake-like crystal with a specific gravity of 1.26 and a melting point of 235°C. It has low pollution potential. When the dosage exceeds 2 parts, frosting may occur. It is a comprehensive rubber antioxidant that resists heat, oxygen, and atmospheric aging. It is an excellent copper inhibitor and has an activating effect on thiazole accelerators. Rubber Antioxidant DNP has a synergistic effect when used with MB, DOP, etc. It is suitable for natural rubber and synthetic rubbers such as chloroprene rubber, styrene-butadiene rubber, and butadiene rubber. The general dosage is 0.2 to 1 part.

5. Rubber Antioxidant NBC: The trade name is Rubber Antioxidant NBC, which appears as a dark gray powder, with a melting point not lower than 83°C. It is non-polluting, easy to disperse, and an excellent ozone inhibitor. It can be used in rubber that is heat-resistant, atmospheric aging-resistant, and crack-resistant. In chloroprene rubber and chlorinated ether rubber, it can improve heat resistance and thermal stability. It is suitable for synthetic rubbers such as chloroprene, chlorinated ether, chlorinated polyethylene, nitrile rubber, and styrene-butadiene rubber, with a dosage of 1 to 2 parts.