Rubber products are closely related to rubber. As a pro […]
Rubber products are closely related to rubber. As a professional rubber additives industry, it is necessary to understand rubber.
Rubber is a highly elastic polymer compound. It has high elasticity that other materials do not have, and is therefore also called an elastomer. The main characteristics of rubber are large molecular weight, generally in the hundreds of thousands, or even up to a million or so; secondly, the rubber has polydispersity, that is, the rubber molecules are of different sizes, there is a distribution range, which is the rubber Be the intrinsic reason for engineering materials.
Second, the characteristics of rubber
It has good flexibility, variability, good strength and tear strength, good water impermeability, gas impermeability, acid and alkali resistance and insulation.
Third, common rubber classification and rubber
Rubber is divided into natural rubber and synthetic rubber according to the preparation and source; rubber is divided into two types according to the use of general and special types. First introduce natural rubber and synthetic rubber:
1. Natural rubber (NR)
The raw material of natural rubber is derived from rubber plant trees. The advantages are: good elasticity, high strength, good insulation, small deformation and convenient processing. The disadvantages are: oil resistance, poor temperature resistance, and aging, all of which are used in combination. General production of car tires and some shock-absorbing and wear-resistant rubber parts.
2, synthetic rubber
Synthetic rubbers are: styrene-butadiene rubber (SBR), nitrile rubber (NBR), butadiene rubber (BR), ethylene propylene rubber (EPDM), butyl rubber (IIR), neoprene (CR), acrylate rubber ( ACM), hydrogenated nitrile (HNBR), chlorosulfonated polyethylene (CSM), fluorine rubber (FKM), silicone rubber (MVQ), and the like.
2.1 EPDM (EPDM)
Advantages: excellent aging resistance, weather resistance, good electrical insulation, good impact elasticity and oil resistance.
Disadvantages: slow vulcanization rate, self-adhesive properties, poor thermal tear properties, and poor processing properties.
Uses: manufacturing heat-resistant conveyor belts, steam hoses, chemical-resistant seals, cushions and waterproof materials, and automotive skins, aprons, etc.
2.2 nitrile rubber (NBR)
Advantages: Excellent oil resistance, good heat resistance, aging resistance, wear resistance, corrosion resistance and other properties.
Disadvantages: poor cold resistance, acid resistance, electrical insulation, etc., and poor resistance to tear strength.
Uses: Mainly used in the manufacture of oil seals, shaft seals and gaskets (O-rings) and other products, can also be used to manufacture oil-resistant hoses, conveyor belts, rubber rollers, vacuum hoses, shock absorbers and textile accessories.
2.3 styrene butadiene rubber (SBR)
Advantages: good heat resistance, aging resistance and wear resistance.
Disadvantages: cold resistance, elasticity, resistance to flexion, cracking, tear resistance, etc., poor performance, poor processability, small change in plasticity, large deformation in calendering, and poor self-adhesiveness.
Uses: Mainly used for pneumatic tires, followed by rubber shoes, hoses, tapes, rubber rollers, tapes and model products, vacuum cleaner seals, etc. such as suction seals.
2.4 neoprene rubber (CR)
Advantages: resistance to futurism, heat resistance, aging resistance, acid and alkali resistance, good elasticity, and good air tightness. It has cold resistance and water resistance.
Disadvantages: poor storage stability, easy to crystallize, and poor electrical insulation.
Uses: Mainly produces rubber parts in home appliances and air conditioners.
2.5 Butadiene or Polybutadiene Rubber (BR)
Advantages: good elasticity, low temperature resistance and wear resistance.
Disadvantages: low tensile strength, low tear strength, poor wet skid resistance, and poor adhesion.
Uses: Mainly used in the manufacture of tires, but also in the manufacture of wear-resistant products (such as rubber shoes, rubber rollers), cold-resistant products and anti-vibration products.
2.6 butyl rubber (IIR)
Advantages: The biggest feature is good air tightness, weather resistance, light aging resistance, chemical resistance, and high temperature resistance and cold resistance. The long-term working temperature can be below 130 °C; the effect of absorbing shock or absorbing vibration is better. Good, electrical insulation is better.
Disadvantages: the elasticity is not as good as natural rubber, the vulcanization rate is slow, the processing performance and the viscosity are poor.
Uses: Most suitable for pneumatic inner tube, followed by underground cable, high voltage cable, radiation protection gloves, chemical equipment lining and anti-vibration rubber products.
2.7 acrylate grease (ACM)
Advantages: It has good heat and oil resistance and is stable in lubricating oil containing sulfur, phosphorus and chlorine additives. At the same time, it is resistant to aging, oxygen and ozone, UV resistance and air tightness. Operating temperature range: about -25 to +150 °C.
Disadvantages: poor cold resistance, water resistance, steam resistance and organic and inorganic acids and alkalis. It is severely expanded in a water-soluble solution such as methanol, ethylene glycol or ketone ester. At the same time, the elasticity and wear resistance are poor, the electrical insulation is poor, and the processing performance is poor.
Uses: It can be used to manufacture oil-resistant, heat-resistant and aging-resistant products such as seals, hoses, chemical linings, etc.
2.8 hydrogenated nitrile rubber (HNBR)
Advantages: high mechanical strength and wear resistance, heat resistance is better than NBR when cross-linked with peroxide, and other properties are the same as nitrile rubber. Operating temperature range: about -30 ~ +150 ° C.
Disadvantages: the price is higher.
Uses: Mainly used in oil resistant and high temperature resistant sealing products.
2.9 chlorosulfonated polyethylene (CSM)
Advantages: Excellent ozone and aging resistance, and weather resistance is superior to other rubbers. Flame retardant, heat resistant, solvent resistant and resistant to most chemicals and acid and alkali resistant. Electrical insulation is acceptable, and wear resistance is similar to styrene butadiene rubber. Operating temperature range: about -20 ~ +120 °C.
Disadvantages: poor tear resistance and poor processing performance.
Uses: wire and cable sheathing, hose, tape, rubber roller chemical lining.
2.10 fluororubber (FKM)
Features: good wear resistance, good weather resistance, light aging resistance, ozone aging resistance, radiation resistance, gasoline, benzene, toluene, alcohol, weak acidity, temperature range: about -20 ~ +200 ° C, Special grade -35 ~ +250 ° C (can work at 250 ° C for a long time).
Disadvantages: This glue is expensive.
Uses: It mainly produces rubber and oil resistant and high temperature resistant rubber products which are resistant to vacuum and high temperature (such as airplanes and rockets).
2.11 Silicone Rubber (MVQ)
Advantages: high temperature resistance (up to 300 °C) and low temperature resistance (minimum -100 °C), it is the best cold and high temperature resistant rubber at present; excellent electrical insulation, high stability to thermal oxidation and ozone, chemically inert Big.
Disadvantages: low mechanical strength, poor resistance to oil, solvent and acid and alkali, difficult to vulcanize, and more expensive.
Uses: Used to make high temperature resistant products (hose, seals, etc.), high temperature wire and cable insulation. Because it is non-toxic and tasteless, it is also used in the food and medical industries.
2.12 isoprene rubber (IR)
It is widely used in the tire manufacturing industry due to its stable chemical properties. It has good elasticity, cold resistance (glassization temperature -68 ° C) and high tensile strength. Under the condition of oxidation resistance and multiple deformation, the tear resistance is higher than that of natural rubber, but the processing properties such as mixing and calendering are slightly worse than natural rubber.
3, mixing rubber
The raw rubber is added with a vulcanizing agent, a promoter, an active agent, a reinforcing agent, a filler, a softening agent, an anti-aging agent, an anti-aging agent and the like, and is uniformly blended in the rubber mixing machine, and the obtained rubber is called Mixing glue.