What is Urethane Rubber Used For?

Polyurethane rubber is a series of elastomer materials containing more urethane groups on the polymer main chain. It is actually a polyurethane rubber, referred to as urethane rubber or urethane rubber for short. Polyurethane elastomer. In addition to urethane groups, polymer chains also contain ester, ether, urea, aryl, and aliphatic chains. It is usually formed by the reaction of oligomer polyol, polyisocyanate and chain extender. Polyurethane rubber forms different structures and types with different raw materials and ratios, reaction methods and conditions.

Chinese name: Polyurethane rubber

English name: polyurethane rubber
nickname: Urethane rubber Polyurethane elastomer

Overview of polyurethane rubber

The code name (UR) is a polymer of polyester (or polyether) and diisocyanamide. Its chemical structure is more complex than that of general elastic polymers. In addition to the recurring urethane groups, the molecular chain often contains groups such as ester groups, ether groups, and aromatic groups.

The main chain of the UR molecule is composed of a flexible segment and a rigid segment inlaid; the flexible segment is also called a soft segment and is composed of an oligomeric polyol (such as polyester, polyether, polybutadiene, etc.); the rigid segment is It is called a hard segment and is composed of a reaction product of a diisocyanate (such as TDI, MDI, etc.) and a small molecule chain extender (such as a diamine and a glycol). Soft segments account for more than hard segments. The soft and hard segments have different polarities, and the hard segments are more polar and easily aggregated together, forming many micro-differentiations in the soft segment phase. This is called a microphase separation structure. Its physical mechanical properties and microphases The degree of separation has a lot to do with it.

UR molecules have high strength and high elasticity due to the existence of forces acting on them by hydrogen bonds.

Features: It has the advantages of high hardness, good strength, high elasticity, high abrasion resistance, tear resistance, aging resistance, ozone resistance, radiation resistance, and good electrical conductivity, which are unmatched by ordinary rubber.

Classification of polyurethane rubber

The traditional classification of polyurethane elastomers is divided according to processing methods ^[1] , which are divided into cast polyurethane elastomers, kneaded polyurethane elastomers and thermoplastic polyurethane elastomers. Due to different raw materials, synthesis and processing methods, and application purposes, reaction-injection polyurethane elastomers (RIMPU) and solution-dispersed polyurethane elastomers have appeared. According to the formed form, it is divided into solid system and liquid system. It is also divided according to the chemical composition of the raw materials. Generally, it is different from polyester or polyether, so there are polyether polyurethane elastomer and polyester polyurethane elastomer.

Polyurethane rubber properties:

(1) Excellent abrasion resistance: Abrasion resistance is the highest among all rubbers. Laboratory test results show that the abrasion resistance of UR is 3 to 5 times that of natural rubber, and it is often as high as about 10 times in practical applications.

(2) High strength and good elasticity in the range of Shore A60 to Shore A70 hardness.

(3) Good shock absorption. At room temperature, the UR damping element can absorb 10% to 20% of the vibration energy. The higher the vibration frequency, the greater the energy absorption.

(4) Good oil and chemical resistance. UR has less affinity with non-polar mineral oils. It has almost no erosion in fuel oils (such as kerosene, gasoline) and mechanical oils (such as hydraulic oil, motor oil, lubricating oil, etc.). Comparable with nitrile rubber. The disadvantage is greater swelling in alcohols, esters, ketones and aromatics.

(5) The coefficient of friction is high, generally above 0.5.

(6) Low temperature resistance, ozone resistance, radiation resistance, electrical insulation, and good adhesion.

Polyurethane rubber vulcanization system:

There are three types of vulcanizing agents: isocyanates, peroxides, and sulfur. The common varieties of isocyanate vulcanizing agents are TDI and its dimers, MDI dimers, and PAPI. , Pay attention to environmental humidity when using), can produce products with good abrasion resistance, high strength and hardness; Dicumyl peroxide (DCP) is the most commonly used peroxide curing agent, peroxide curing PUE products have good dynamic performance, small compression set, good elasticity and aging resistance. The disadvantage is that they cannot be directly vulcanized with steam, and the tear strength is poor. PUE containing unsaturated segments can be vulcanized with a sulfur system. Generally, it is 1.5 ~ 2 parts. Accelerators M and DM are the most commonly used, generally around 6 parts. The comprehensive performance of vulcanized products is better.

Polyurethane rubber application:

First of all, it can be applied to track and field plastic track sports fields, including basketball, volleyball, badminton and tennis courts. There are indoor and outdoor types. This kind of plastic site has a longer service life than wood flooring, and is suitable for wear resistance, oil resistance, weather resistance and aging. Polyurethane rubber has excellent oil resistance, so it is also used as an oil-resistant drum. Due to its excellent performance, it can replace other alloys in the automotive industry and can be used in automotive bumpers, steering wheels, and automotive peripheral components. Secondly, because of the advantages of low abrasion, high friction coefficient and low noise, the transfer device made by him has a stable speed. Therefore, coal mine and mining conveyor belts can be made of polyurethane compound rubber, high hardness polyurethane casting glue can be used as gear mercury gear, has the characteristics of stable liquid transmission. In addition, it is also used as a lining and a protective layer for non-metallic car snow chains and high-rise building rescue water pipe linings; for high-pressure seals and high-pressure water pipes; it can reduce costs in terms of shoemaking, and is beautiful; Wall oil tanks, oil-resistant seals, dust-proof seals; as potting materials for cable streets, electronic components and printed circuits, and as ideal anti-vibration rubber, and also have a wide range of uses in human organs and medical and sanitary appliances.

Secondly, it is also used in the field of defense industry, such as polyurethane insulation materials in aerospace systems, which have the advantages of excellent bonding performance and high strength.

Application examples:

1: It is used for discharging and peeling rubber pad on the die.

2: It has been widely used in punching, bending, shallow drawing and forming processes.