What is polyurethane elastomer?

Reference:

Since the early 198s, polyurethane elastomer has changed from military to military and civilian use, and since then, the variety and brand of products have been increasing, and the production scale has been expanding day by day, which has played an increasingly important role in all sectors of the national economy and people's food, clothing, housing and transportation.

Polyurethane elastomer is a kind of polyurethane synthetic material. Because of its soft and hard segments, it can be designed by molecules to give the material excellent properties such as high strength, good toughness, wear resistance and oil resistance. It has both the high elasticity of rubber and the rigidity of plastic, so it is called "wear rubber".

Polyurethane elastomer can be molded by plastication, mixing and vulcanization (MPU) just like general rubber. It can also be made into liquid rubber, cast and molded or sprayed, encapsulated and centrifugally molded (referring to CPU); It can also be made into granular materials, which are shaped by injection, extrusion, calendering, blow molding and other processes (referring to CPU) just like ordinary plastics. Molded or injection molded parts can also be machined such as cutting, grinding and drilling within a certain hardness range. Due to the diversity of processing, the applicability of polyurethane elastomer is very wide, and the application field is expanding.

oil resistance, ozone resistance, aging resistance, radiation resistance, low temperature resistance, good sound permeability, strong adhesion, excellent biocompatibility and blood compatibility. These advantages are the reasons why polyurethane elastomers have been widely used in military industry, aerospace, acoustics, biology and other fields.

The main advantages of polyurethane elastomer are:

1. The adjustable range of performance is large. Many physical and mechanical performance indexes can be changed in a certain range through the selection of raw materials and the adjustment of formula, so as to meet the different requirements of users for the performance of products. For example, hardness is often an important index for users. Polyurethane elastomer can be made into both soft printing cots with Shore A hardness of about 2 and hard steel rolling cots with Shore D hardness of over 7, which is difficult for ordinary elastomer materials to do. Polyurethane elastomer is a polar polymer material composed of many flexible segments and rigid segments. With the increase of the proportion of rigid segments and the density of polar groups, the original strength and hardness of elastomer will increase accordingly.

2, excellent wear resistance. Especially in the presence of water, oil and other wetting media, its wear resistance is often several times to dozens of times that of ordinary rubber materials. Although metal materials such as steel are hard, they are not necessarily wear-resistant. For example, in a large-scale water pump in the Yellow River irrigation area, the metal mouth ring and protection ring, which are the overflow parts, are seriously worn and leaked in less than a few hundred hours after being washed by a lot of sediment, while the mouth ring and protection ring coated with polyurethane elastomer are still not worn after continuous operation for 18 hours. Other materials, such as rubber roller of rice husker, sieve plate of vibrating screen for coal preparation, track track of sports ground, dynamic oil sealing ring for crane forklift, elevator wheel and roller skates, are also useful places of polyurethane elastomer. It should be mentioned here that a small amount of lubricants such as aluminum disulfide, graphite or silicone oil can be added to this kind of polyurethane elastomer to improve the friction coefficient of medium and low hardness polyurethane elastomer and improve the wear resistance under load.

disadvantages of urethane elastomer:

1. The endogenous heat is large and the high temperature resistance is average. Normal use temperature range is -4~12℃. If it needs to work under high frequency oscillation or high temperature for a long time, corresponding modification measures must be taken in structural design or formula.

2, not resistant to strong polar solvents and strong acid-base media. At a certain temperature, alcohol, acid and ketone will swell and degrade polyurethane elastomer, while solvents such as chloroform, dichloromethane, dimethylformamide and trichloroethylene will swell polyurethane elastomer at room temperature.

Common application fields:

<; /p> < /p> < /p> 1. Polyurethane elastomer for automobile. Today's automobile industry is developing in the direction of high performance, low weight, comfort and safety. Rubber-plastic synthetic materials are gradually replacing metal materials, which opens up a very broad prospect for the application of polyurethane elastomers. Goodrich Company of the United States has developed the second generation TPU, and its business name is Estaloc. This product keeps the characteristics of the first generation TPUEstaloc, and uses hollow glass balls as fillers, which improves the gloss by more than 15%. It can be used to manufacture automobile side panels and shock absorbers. Installing airbags on cars is the need of the development of modern automobile industry and plays an important role in protecting the life safety of drivers. This kind of airbag must have certain strength to withstand high-speed impact and good low-temperature flexibility, so it is suitable to be made of polyurethane, and the amount of glue used for each airbag is about 3 grams. Most cars in China have not been equipped with airbags, and the market demand is great. Using the high strength and bearing capacity of polyurethane elastomer. It can be used to manufacture tires for medium and low-speed trucks with high strength and bearing capacity, and its bearing capacity is 7 times that of tires of the same specification made of natural rubber. In recent years, a new type of green polyurethane composite tire is under research and development. It is based on the old and new rubber flat tires and poured with a certain thickness of high wear-resistant and puncture-resistant polyurethane rubber surface. At present, it is in the mileage test stage and is expected to be put into production soon.

2. Polyurethane elastomer for building. The traditional asphalt felt waterproof material has been gradually replaced by durable and integral polyurethane waterproof material; Ten years ago, only national official competition venues used polyurethane paving materials for the runways of sports fields, but now most provincial and municipal stadiums, colleges and even some primary and secondary schools have paved polyurethane plastic runways; The expansion joints of large bridges, airport runways and highway caulking have also begun to use polyurethane elastomer cured at room temperature to make sleepers for high-speed railways, which is an ideal material. The sleepers laid on the tunnels and bridges through which the Shinkansen Railway in Japan passes are made of polyurethane elastomer. This new application gives full play to the characteristics of poly (chloric acid), such as light elasticity, good shock absorption and aging resistance, and has good popularization value.

3. Polychlorinated elastomer for mining. Coal mines, metal and nonmetallic mines have a great demand for nonmetallic materials with high wear resistance, high strength and elasticity. In recent 1 years, many selected coal plants have replaced heavy metal sieve plates with flexible PVC sieve plates, which not only greatly prolongs the service life of sieve plates, but also significantly reduces the noise in the operating environment, and has obvious energy-saving and consumption-reducing effects. Others, such as cyclone used for solid separation, flame-retardant and antistatic wear-resistant conveyor belt, solid core wheel of mine monorail crane, combined plate for coal mine shotcrete machine, oil sealing ring on 1,-ton electric wheel dump truck, and cold patching glue for high-voltage cable sheath, have also played a great role in mine construction. At present, there are many wear-resistant elastic products for mines waiting for us to develop and popularize.

4. Polyurethane elastomer for shoes. Since Taiwanese businessmen came to the mainland in succession, China's footwear industry has developed rapidly. Polyurethane elasticity has the advantages of good cushioning performance, light weight, wear resistance and anti-slip, and has now become an important supporting material in the shoemaking industry. The soles, heels, toe caps, insoles and other important accessories of many shoes, such as golf shoes, baseball shoes, football shoes, ski shoes, safety shoes, etc., are made of polyurethane elastomer, which is not only beautiful and elegant, but also comfortable and durable, and can also improve sports performance.

5. medical polyurethane elastomer. Good biocompatibility, blood compatibility and no additives are important reasons for the application of TPU and CPU materials in medical field. At present, the medical elastomer products that have been successfully developed include: tracheal cannula, prosthesis, suppository for family planning, skull defect repair materials, condoms, etc., and their application prospects in medical and health fields are still very broad.

6. New polyurethane composite board. Britain is developing a kind of polyurethane composite board called SPS plywood system, which will bring a revolution to shipbuilding industry. It consists of two layers of 9mm thick steel plates and 4mm thick polyurethane elastomer injected between them. Once it is successfully developed, it can replace the traditional reinforced steel plate material used in shipbuilding industry. Its advantages are: saving manufacturing time, saving steel plates, reducing hull weight, impact resistance, fatigue resistance, shock absorption, noise reduction and heat insulation. Once the composite materials of SPS system are used to build ships in the future, the polyurethane elastomer consumed by shipbuilding industry will be a very amazing number.