The Application of Polyurethane Elastomers Can be Really Extensive
1. The adjustable range of performance is large. A number of physical and mechanical performance indicators can be changed within a certain range through the selection of raw materials and the adjustment of formula, so as to meet the different requirements of users for product performance. For example, hardness is often an important indicator for users of products. Polyurethane elastomers can be made into soft printing rubber rollers with Shore A hardness of about 20, and hard steel rolling rubber rollers with Shore D hardness of more than 70. This is difficult to achieve with general elastomer materials. Polyurethane elastomer is a polar polymer material composed of many flexible segments and rigid segments. As the ratio of rigid segments increases and the density of polar groups increases, the original strength and hardness of the elastomer will increase accordingly.
2. Superior wear resistance. Especially under the working conditions where there are wetting media such as water and oil, its wear resistance is often several times to dozens of times that of ordinary rubber materials. Although metal materials such as steel are very hard, they are not necessarily wear-resistant. For example, in the large-scale water pump in the Yellow River irrigation area, the metal mouth ring and protection ring of the over-current components have been washed by a large amount of sediment, and they will be severely worn and leaked within a few hundred hours. , and the mouth ring and protective ring covered with polyurethane elastomer have been continuously operated for 1800 hours without being worn. Others, such as the rubber rollers for rice milling, vibrating screen sieves for coal preparation, track race tracks in sports fields, dynamic oil seals for cranes and forklifts, elevator wheels and roller skate wheels, etc. are also polyurethane elastomers. of use. A point to be mentioned here is that in order to improve the friction coefficient of low and medium hardness polyurethane elastomer parts and improve the wear resistance under load, a small amount of aluminum disulfide, graphite or silicone oil can be added to this type of polyurethane elastomer. lubricant.
3. Various processing methods and wide applicability. Polyurethane elastomers can be molded by plasticizing, kneading and vulcanization processes (refer to MPU) like general-purpose rubbers; they can also be made into liquid rubber, cast molding or spraying, potting, centrifugal molding (referring to CPU); Pellet material, like ordinary plastic, is formed by injection, extrusion, calendering, blow molding and other processes (referring to CPU). Molded or injection molded parts can also be processed by cutting, grinding, drilling and other machining within a certain hardness range. The diversity of processing makes the applicability of polyurethane elastomers very wide, and the application fields continue to expand. 4. 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 reason why polyurethane elastomers are widely used in military, aerospace, acoustics, biology and other fields.
Disadvantages of Esterurethane Elastomers
But polyurethane elastomer is not perfect, its main disadvantages are:
1. Large endogenous heat and general high temperature resistance. The normal operating temperature range is -40~120℃. If it needs to be used for a long time under high frequency oscillation conditions or high temperature conditions, 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, alcohols, acids and ketones will swell and degrade polyurethane elastomers, and solvents such as chloroform, dichloromethane, dimethylformamide, and trichloroethylene will swell polyurethane elastomers at room temperature.
Application and Development of Polyurethane Elastomers
In summary, the comprehensive properties of polyurethane elastomers are very superior. In recent years, all countries have been strengthening their application development research according to market demand. The development focuses on the following aspects:
1. Polyurethane elastomers for automobiles. Today's automotive industry is moving towards high performance, low weight, comfort and safety. Rubber and plastic synthetic materials are gradually replacing metal materials, which opens up extremely broad prospects for the application of polyurethane elastomers. Goodrich Company of the United States has developed the second generation TPU, and its business name is Estaloc. The product maintains the characteristics of the first-generation TPU Estaloc, and uses hollow glass spheres as fillers, which increases the gloss by more than 15%, and can be used to manufacture automobile side panels and shock pads. The installation of airbags on automobiles is the need for the development of the modern automobile industry, and plays an important role in protecting the life safety of drivers. This kind of airbag must have a certain strength to withstand high-speed impact, and also have good low-temperature flexibility. It is suitable to be made of polyurethane. The amount of glue used for each airbag is about 300 grams. Most of the cars in our country have not yet installed airbags, and the market demand is huge. Utilize the high strength and high load-bearing capacity of polyurethane elastomers. It can manufacture tires for medium and low-speed heavy-duty vehicles, with high strength and high bearing capacity, and can manufacture tires for medium and low-speed heavy-duty vehicles. In recent years, a new type of green polyurethane composite tire is being researched and developed. It is based on new and old rubber bare tires, and is poured with a certain thickness of high wear-resistant and puncture-resistant polyurethane rubber surface layer. It is currently in the mileage test. stage, and is expected to be put into production soon.
2. Polyurethane elastomer for construction. The traditional asphalt linoleum waterproof material has been gradually replaced by the durable and integrally constructed polyurethane waterproof material; only 10 years ago, only the national official competition venues used the polyurethane pavement material for the runway of the sports field, and now most provincial and municipal stadiums, Polyurethane plastic runways have been installed in colleges and universities, and even some primary and secondary schools; expansion joints of large bridges, airport runways and caulking of highways have also begun to use room temperature cured polyurethane elastomers to make sleepers for high-speed railways It is a very ideal material. The sleepers laid on the tunnels and bridges of the Shinkansen railway in Japan are made of polyurethane elastomer. This new application gives full play to the characteristics of polychloric acid elastomers, such as light weight, good shock absorption, and aging resistance, and is very valuable for promotion.
3. Polyester elastomer for mining. Coal mines, metal and non-metal mines are in great demand for non-metallic materials with high wear resistance, high strength and elasticity. In the past 10 years, many coal plants have replaced the cumbersome metal sieve plates with polyurethane elastic screen plates, which not only greatly prolongs the service life of the sieve plates, but also significantly reduces the noise of the operating environment, resulting in obvious energy saving and consumption reduction effects. Others such as cyclone for solid separation, flame-retardant and anti-static wear-resistant conveyor belt, solid core wheel for mining monorail crane, coupling plate for coal mine shotcrete machine, oil sealing ring on 10,000-ton electric wheel dump truck , cold repair glue for high-voltage cable jackets, etc. have also played a huge role in mine construction. There are still many wear-resistant elastic products for mines waiting for us to develop and promote.
4. Polyester elastomer for shoes. Since Taiwanese businessmen came to the mainland one after another, my country's footwear industry has developed rapidly. Polyester elasticity has the advantages of good cushioning performance, light weight, wear resistance, anti-skid, etc. It has become an important supporting material in the shoe industry, golf shoes, baseball shoes, football shoes, ski shoes, travel shoes, safety shoes. The sole, heel, toe, insole and other important accessories of many shoes are made of polyurethane elastomer, which is not only beautiful, but also comfortable and durable, and can improve sports performance.
5. Medical polyurethane elastomer. Good biocompatibility, blood compatibility, and no various additives are important reasons for the application of TPU and CPU materials in the medical field. At present, the successfully developed medical elastomer products include: tracheal cannula, prosthesis, embolization agent for family planning, skull defect repair materials, condoms, etc., and their application prospects in the medical and health field are still very broad.
6. New type of polyurethane composite sheet. The UK is developing a polyurethane composite sheet called the SPS plywood system that will revolutionise the shipbuilding industry. It consists of two layers of 9mm thick steel plates and a 40mm thick polyurethane elastomer injected into them. Once developed successfully, it can replace the traditional reinforced steel plate materials used in shipbuilding. Its advantages are: saving manufacturing time, saving steel plates, and reducing the weight of the hull , Impact resistance, fatigue resistance, shock absorption, noise reduction, heat insulation. Once the composite materials of the SPS system are used to build ships in the future, the consumption of polyurethane elastomers in the shipbuilding industry will be a very staggering number.
