Rubber auxiliary products are closely related to rubber, as a professional rubber auxiliary industry personnel is necessary to understand rubber.
I. Rubber
Rubber is a kind of high elastic polymer. It has a high elasticity not found in other materials, so it is also called elastomer. The main characteristic of rubber is that the molecular weight is large, generally in hundreds of thousands, even up to millions of about; Secondly, rubber has polydispersity, that is, rubber molecules are unequal in size and have a distribution range, which is the internal reason that determines rubber to become engineering materials.
Two, the characteristics of rubber
Has good flexibility, changeability, strength, and tear strength is good, has good water permeability, air permeability, acid and alkali resistance and insulation.
Three, common rubber classification and rubber
Rubber is divided into natural rubber and synthetic rubber according to the production and source; According to the use of rubber is divided into general type and special type two categories. Natural gum and synthetic gum:
1. Natural glue (NR)
The raw material of natural gum comes from the rubber plant tree. Its advantages are: good elasticity, high strength, good insulation, small deformation, convenient processing. Its disadvantages are: oil resistance, poor temperature resistance, easy aging, are used with blending. General production of automobile tires and some shock - absorbing wear-resistant rubber parts.
2. Synthetic glue
Synthetic gum: styrene butadiene gum (SBR), butadiene gum (NBR), butadiene gum (BR), ethylene gum (EPDM), butyl gum (IIR), neoprene gum (CR), acrylic gum (ACM), hydrogenated butadiene (HNBR), chlorosulfonated polyethylene (CSM), fluorine gum (FKM), silicone rubber (MVQ), etc.
2.1 EPDM
Advantages: Excellent aging resistance, weather resistance, good electrical insulation, good impact elasticity, oil resistance.
Disadvantages: curing speed is slow, self-adhesive, thermal tearing performance is poor, processing performance is not good.
Uses: Manufacture heat-resistant transport belt, steam hose, chemical resistant seals, cushioning and waterproof materials and automotive leather bowl, leather ring, etc.
2.2 Nitrile Gum (NBR)
Advantages: Excellent oil resistance, but also has good heat resistance, aging resistance, wear resistance, corrosion resistance and other properties.
Disadvantages: cold resistance, acid resistance, electrical insulation and other properties are poor, and resistance to tear strength is poor.
Uses: Mainly used in the manufacture of oil seals, shaft seals and gaskets (O-ring) and other products, can also be used in the manufacture of oil resistant hose, transport belt, cots, vacuum hose, shock absorbing products and textile accessories.
2.3 Styrene butadiene Gum (SBR)
Advantages: Good heat resistance, aging resistance and wear resistance.
Disadvantages: cold resistance, elasticity, resistance to flexure, cracking, tear resistance and other properties are poor, and the processing performance is poor plasticity change, calendering deformation, poor self-viscosity.
Uses: Mainly used for pneumatic tires, followed by rubber shoes, rubber hose, tape, cots, rubber cloth and model products, vacuum cleaner seal ring such as suction seal ring.
2.4 Chloroprene rubber (CR)
Advantages: flexure resistance, heat resistance, aging resistance, good acid and alkali resistance, and good elasticity, good air tightness. It has cold resistance and water resistance.
Disadvantages: poor storage stability, easy crystallization, poor electrical insulation.
Uses: Mainly produces rubber parts in household appliances and air conditioners.
2.5 Butadiene or polybutadiene rubber (BR)
Advantages: elasticity, low temperature resistance, good wear resistance.
Disadvantages: tensile strength, tear strength is low, wet skid resistance is not good, poor viscosity.
Application: Mainly used in the manufacture of tires, but also can be used in the manufacture of wear-resistant products (such as rubber shoes, cots), cold resistant products and shock-proof products.
2.6 Butyl adhesive (IIR)
Advantages: The biggest feature is good air tightness, weather aging resistance, light aging resistance, chemical resistance, and high temperature resistance, cold resistance, long-term working temperature can be below 130℃; Shock absorption or shock absorption effect is better, electrical insulation is better.
Disadvantages: not as elastic as natural rubber, curing speed is slow, processing performance, poor viscosity.
Uses: Most suitable for inflatable inner tube, followed by underground cables, high voltage cables, radiation gloves, chemical equipment lining and shock-proof rubber products.
2.7 Acrylic Gum (ACM)
Advantages: Good heat and oil resistance, stable performance in lubricating oil containing sulfur, phosphorus and chlorine additives. At the same time, aging resistance, oxygen and ozone resistance, UV resistance, good air tightness. Operating temperature range: about -25 ~ +150℃.
Disadvantages: poor cold resistance, water resistance, steam resistance and organic and inorganic acid, alkali. In methanol, ethylene glycol, ketone ester and other water-soluble solution expansion is serious. At the same time, the elasticity and wear resistance are poor, the electrical insulation is poor, and the processing property is poor.
Use: Can be used to manufacture oil resistant, heat resistant, aging resistant products, such as seals, hose, chemical lining, etc.
2.8 Hydrogenated nitrile gum (HNBR)
Advantages: High mechanical strength and wear resistance, better heat resistance than NBR when crosslinking with peroxide, other properties and nitrile rubber. Operating temperature range: about -30 ~ +150℃.
Cons: Higher price.
Purpose: Mainly used in oil and high temperature resistant sealing products.
2.9 Chlorosulfonated Polyethylene (CSM)
Advantages: Excellent ozone resistance and aging resistance, better weather resistance than other rubber. Flame retardant, heat resistance, solvent resistance and resistance to most chemicals and acid and alkali resistance is good. The electrical insulation is acceptable and the wear resistance is similar to that of styrene butadiene rubber. Operating temperature range: about -20 ~ +120℃.
Disadvantages: poor tear resistance, poor machining performance.
Uses: wire and cable sheathing, rubber hose, tape, rubber roller chemical lining.
2.10 Fluorine Rubber (FKM)
Features: Good wear resistance, good weather aging resistance, light aging resistance, ozone aging resistance, radiation resistance, gasoline, benzene, toluene, alcohol, weak acid excellent, use temperature range: about -20 ~ +200℃, special grade -35 ~ +250℃(can work at 250℃ for a long time).
Disadvantages: This glue is expensive.
Uses: Mainly produces vacuum resistance, high temperature resistance (such as aircraft, rockets) chemical corrosion resistance, oil resistance, high temperature resistance rubber products.
2.11 Silicone Rubber (MVQ)
Advantages: both high temperature resistance (maximum 300℃) and low temperature resistance (minimum -100℃), is currently the best cold resistance, high temperature resistance rubber; At the same time, good electrical insulation, high stability to thermal oxidation and ozone, chemical inertness.
Disadvantages: low mechanical strength, oil resistance, solvent resistance and acid and alkaline resistance, more difficult to vulcanize, the price is more expensive.
Purpose: Used for making high and low temperature resistant products (rubber hose, seals, etc.), high temperature resistant wire and cable insulation layer. Because it is non-toxic and odorless, it is also used in the food and medical industries.
2.12 Isoamyl Rubber (IR)
Its stable chemical properties are widely used in the tire manufacturing industry. It has good elasticity, cold resistance (vitrification temperature -68℃) and high tensile strength. In the oxidation resistance and multiple deformation conditions, the notched tear resistance is higher than that of natural rubber, but the processing properties such as mixing, calendering and so on are slightly worse than that of natural rubber.
3, mixing rubber
Raw rubber adding vulcanizing agent, accelerator, active agent, reinforcing agent, filler, softener, antioxidant, anti-cross agent and other adjuvants, mixed evenly in the rubber mixer, and the produced rubber is called mixing.
