Polychloroprene CAS 9010-98-4

Examples of excellent weather resistance of neoprene include wires and cables, and their actual use time is as long as 20 to 30 years.

In terms of weather resistance in a broad sense, it should have the properties of UV resistance, heat resistance, cold resistance, water erosion resistance, sand erosion resistance and wind erosion resistance, as well as ozone aging resistance and other properties. The volume glue content of the weather resistance formula is generally more than 50%. When the weather resistance is required to be high, the carbon black formula should be used, and at least 10 parts of fine particle furnace carbon black should be used. Inorganic fillers are preferably clay and calcium silicate. The formula of light-colored products needs to be combined with ultraviolet shielding agent, and iron oxide red, phthalocyanine blue, titanium dioxide, etc. can be used. Anti-aging agent can be used together with heat-resistant and flex-resistant anti-aging agent (amine anti-aging agent) and anti-ozone anti-aging agent (p-phenylenediamine anti-aging agent).

Commonly used are antioxidants A, D, 4010, 4010NA, etc. The dosage of the first two is 1 to 2 parts, the dosage of antioxidant 4010 is 1.5 to 2.0 parts, and the amount of antioxidant 4010NA can be used to 5 parts. Softeners should be saturated hydrocarbons, such as paraffin, Vaseline, etc.

The main points of improving the ozone resistance of neoprene rubber are: adopt a formula with high glue content, the filler should be dispersed evenly, maintain a minimum set elongation performance, and use a strong anti-ozone antioxidant and paraffin to form a protective film on the surface of the product, and In product design, it is in a state of unstressed, etc.

Neoprene is often used to manufacture products such as heat-resistant conveyor belts, hoses, and rubber rollers. After the glue is heated, the rigidity increases, the tensile stress and hardness increase, and the tensile strength and elongation decrease. Usually, as long as the elongation is not extremely reduced, it will not hinder use. Therefore, the key to heat resistant formulations is to maintain elongation and minimize hardening. However, from a practical point of view, other physical properties should also be considered, such as resilience, flexural cracking, compression set resistance, etc. These physical properties can be inferred from changes in hardness and elongation.

It is better to use magnesium oxide and zinc oxide system for the vulcanization system, which is not much different from the lead oxide system. The use of 10 to 15 parts of zinc oxide can improve the heat resistance of the rubber compound, especially to maintain its elasticity. Sulfur or compounds that emit sulfur will reduce heat resistance and make the compound hard. Accelerator NA-22 has the best heat resistance effect, and the dosage is 0.75-1.0 parts, which can be used alone or in combination with DM.

Neoprene rubber is often used as seals, gaskets, gaskets, pads, backing plates and other products, and it pays more attention to compression set. As long as the neoprene is properly formulated, its compression set resistance can completely exceed that of natural rubber. The main points of its recipe are as follows.

1. When mixed with carbon black, the compression set of non-sulfur-adjusted neoprene is smaller than that of sulfur-adjusted neoprene; when mixed with inorganic fillers, the two are roughly equivalent; when low-temperature compression set is required, it should be Use anti-crystalline neoprene, preferably with sulfur.
2. The degree of vulcanization should be high, which can be achieved by extending the vulcanization time, increasing the vulcanization temperature, and increasing the amount of accelerator.
3. Soft carbon black is used for carbon black, and moderate dosage is very effective. Inorganic fillers are not effective, and calcined clay has a certain effect, but it reduces the strength and elongation properties of the rubber compound.
4. Accelerator NA-22 is generally used. If trimethylthiourea is used, the compression set is very small, but the storage stability and elongation are poor. It is best not to use sulfur or sulfuric ointments that release sulfur as accelerators. Among the metal oxides, magnesium oxide and zinc oxide systems are better, and lead oxide systems are worse. Five, flexural crack resistant rubber.

If the elastomer is placed at low temperature, it will lose its characteristic elasticity and harden. In order to distinguish the properties of elastomers at low temperature, it is divided into crystallization (primary transition point) and vitrified neoprene placed at low temperature, which gradually loses rubber elasticity and becomes plastic. It is called rigidification; then it loses toughness and becomes very resistant to deformation, and it is brittle under the action of impact force, which is called embrittlement. The physical phenomena manifested by the glass transition of neoprene include rigidity and embrittlement. Generally, the embrittlement temperature is several degrees lower than the rigidity temperature.

Because neoprene contains chlorine, it has the property of isolating the fire source, that is, self-extinguishing and non-spontaneous combustion. It is often used as flame-resistant rubber products, such as flame-resistant conveyor belts, cable jackets, etc. Antimony trioxide is often used as a flame retardant in the formula. It can combine with chlorine in neoprene rubber to form ladder chloride, which is covered on the surface of the rubber to block the invasion of oxygen and has excellent flame resistance. The dosage of 10-20 parts will not affect the physical properties of the rubber. Zinc borate also improves flame resistance, it melts during combustion and forms a masking film that covers the surface and blocks fuel. The dosage is generally 10 servings. Inorganic fillers have higher flame resistance than carbon black, clay and calcium silicate have better flame resistance, and aluminum hydroxide has better flame resistance. Petroleum plasticizers used as softeners have a combustion-supporting effect. Chlorinated paraffin can decompose at a temperature lower than the decomposition temperature of chloroprene rubber, releasing incombustible gas and reducing flammability. In addition, tricresyl phosphate also has strong flame resistance.