Applications and characteristics of Chloroprene Rubber（CR）

Product name: Neoprene rubber, also known as chloroprene (neoprene) rubber ,Chloroprene Rubber (CR)

Product category: Organic chemical products 

Description: The appearance is milky white to beige or light brown flake or block, does not contain mechanical debris other than talc powder, no burnt particles.

The physical and chemical properties are: a homopolymer made from 2-chloro-1, 3-butadiene by emulsion polymerization. Neoprene rubber relative density (d420) 0.958, melting point -130℃, boiling point 59.4℃, refractive index (nD20) 1.4583, vapor pressure (20.8℃) 26.66kPa. Soluble in ethanol, acetic acid, acetone and other organic solvents, slightly soluble in ethylene glycol, water. Polymerization is easy in the presence of light, heat, ionizing radiation and catalyst. Its molecular weight is generally 100,000 ~ 200,000, the relative density is 1.15 ~ 1.25, the glass transition temperature is -45 ℃, has polarity, regular molecular configuration and reversible crystallization properties.

Main application: Chloroprene Rubber/Neoprene rubber is very widely used, mainly used as wire and cable sheath, rubber hose, oil-resistant rubber products, heat-resistant conveyor belt, printing rubber stick, rubber dam, construction seal, highway sealant, bridge support, waterproof cap for oil field wire, flame retardant rubber products, various sealing rings and chemical equipment anti-corrosion lining and neoprene adhesive. In recent years, neoprene rubber has been developed for new uses in building waterproof materials, sealing materials, adhesives, Marine development, medical and health care, energy development and people's life, and has expanded the application field.

1, weather resistant rubber material

Examples showing that Chloroprene Rubber has excellent weather resistance include wires and cables, and their actual use time is as long as 20 to 30 years. In terms of broad weatherability, it should have the properties of ultraviolet resistance, heat resistance, cold resistance, water erosion resistance, sand erosion and wind erosion, and also have the properties of ozone aging resistance. The volume gum content of the weather resistant formula is generally more than 50%, and when the weather resistance is higher, the carbon black formula should be used, and at least 10 dosage of fine particle furnace carbon black should be combined. Inorganic fillers are clay and calcium silicate. The formula of light-colored products needs to be combined with ultraviolet shielding agent, which can use iron oxide red, phthalocyanine blue, titanium dioxide, etc. The antioxidant can be used in combination with heat and flex resistant antioxidant (amine antioxidant) and anti-ozone antioxidant (p-phenylenediamine antioxidant). Commonly used are antioxidant A, D, 4010, 4010NA, etc., the dosage of the first two is 1 to 2 dosage, the dosage of antioxidant 4010 is l.5 to 2.0 , and the antioxidant 4010NA can be used to 5 dosage. Softener should choose saturated hydrocarbons, such as paraffin, petroleum jelly, etc.

2, ozone resistant rubber material

The key points of improving the ozone resistance of Chloroprene Rubber are: The formulation with high gum content, the dispersion of the filler should be uniform, the fixed elongation performance should be maintained at a minimum, and the use of strong anti-ozone antioxidants and paraffin wax should be used to form a protective film on the surface of the product, and the product design should be in a state free from stress.

3, heat resistant rubber material

Chloroprene Rubber/Neoprene is commonly used to make heat-resistant conveyor belts, hose and rollers. When the adhesive is heated, the rigidity increases, the constant elongation 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, compressive permanent deformation resistance, etc., and these physical properties can be inferred from changes in hardness and elongation.

It is better to use magnesium oxide and zinc oxide system in vulcanization system, and there is little difference between the system and lead oxide system. The use of 10 to 15 dosage of zinc oxide can improve the heat resistance of the compound, especially to maintain its elasticity. Sulfur or compounds that release sulfur will reduce heat resistance and harden the compound. The heat resistance of the accelerator NA-22 is the best, and the dosage is 0.75 ~ 1.0 , which can be used alone or with DM.

4, compression resistant permanent deformation of rubber material

Chloroprene Rubber is commonly used as seals, gaskets, gaskets, gaskets and other products, and pays more attention to compression permanent deformation. As long as the neoprene rubber is properly formulated, its compression resistance and permanent deformation can completely exceed that of natural rubber. The main points of the recipe are as follows.

(1) When combined with carbon black, the compression permanent deformation of non-sulfur modified neoprene rubber is smaller than that of sulfur modified neoprene rubber; When combined with inorganic fillers, the two are roughly equivalent; When low temperature compression is required for permanent deformation, anti-crystallization neoprene rubber should be used, and it is best to use sulfur.

(2) The degree of vulcanization should be high, and it can be achieved by extending the vulcanization time, increasing the vulcanization temperature, increasing the amount of accelerator, etc.

(3) The use of soft carbon black, medium dosage is very effective. The effect of inorganic fillers is not good, among which calcined clay has a certain effect, but it reduces the strength and elongation of the compound.

(4) Accelerators generally use accelerator NA-22. If trimethylthiourea is used, the compression permanent deformation is very small, but the storage stability and elongation are poor. It is best not to use sulfur or sulfide ointment that can release sulfur as a accelerator. In metal oxides, magnesium oxide and zinc oxide systems are better, and lead oxide systems are worse. Fifth, flexural cracking resistant rubber material

5, cold resistant rubber material

If the elastomer is placed at a low temperature, it will lose its characteristic elasticity and harden. In order to distinguish the properties of elastomers at low temperatures, they are divided into crystallization (a transition point) and vitrified Chloroprene Rubber placed at low temperatures, gradually losing rubber elasticity and becoming plastic. It's called rigidization; Then it loses its toughness and becomes very resistant to deformation, which is brittle by impact force, called embrittlement. The physical phenomena of the glass transition of neoprene rubber include rigidity and embrittlement. Generally, the embrittlement temperature is several degrees lower than the rigid temperature.

6. Fire-resistant adhesive material

Chloroprene Rubber contains chlorine, has the non-spontaneous combustion of isolating fire source that is, self-extinguishing, and is often used as fire-resistant rubber products, such as fire-resistant conveyor belts, cable sheathing, etc. Antimony trioxide is often used in the formula as a fire resistant agent, which can be chlorinated with neoprene rubber to generate a ladder of chloride, covered in the surface of the rubber, to block oxygen invasion, with excellent fire resistance. The dosage of 10 ~ 20 will not affect the physical properties of the rubber material. Zinc borate also improves fire resistance by melting as it burns, forming a masking film that covers the surface and blocks the fuel. The dosage is usually 10 . Inorganic fillers have higher fire resistance than carbon black, clay and calcium silicate have better fire resistance, and aluminum hydroxide has better fire resistance. Petroleum plasticizers used as softeners have combustion-supporting effects. Chlorinated paraffin can be decomposed at a lower temperature than the decomposition temperature of neoprene rubber, releasing non-combustible gas to reduce ignition. In addition, trimethylbenzene phosphate also has strong fire resistance.