Wide range of adjustable properties
A number of physical and mechanical performance indexes can be varied within a certain range through the selection of raw materials and adjustment of formulations, so as to meet the different requirements of users for product performance. For example, hardness is often an important indicator of the user’s products, polyurethane elastomers can be made into Shore A hardness of 20 or so soft printing rollers, but also can be made into Shore D hardness of 70 or more hard steel rollers, which is difficult to do with general elastomer materials. Polyurethane elastomer is composed of many flexible chain segments and rigid chain segments of polar polymer materials, with the increase in the proportion of rigid chain segments and the increase in the density of polar groups, the elastomer original strength and hardness will be increased accordingly.
Excellent abrasion resistance
Especially in the presence of water, oil and other wetting media working conditions, its wear resistance is often several times to dozens of times the ordinary rubber materials. Metal materials such as steel, although very hard, but not necessarily wear-resistant, such as the Yellow River irrigation area of large pumps, the overflow components of the metal mouth ring and the protective ring after a large amount of sediment scouring, with less than a few hundred hours on the serious wear and leakage, and the use of polyurethane elastomer-coated mouth ring and the protective ring (cyclone) is running 1800h into the continuous operation of the still unworn. Others, such as rice milling with huller rollers, coal with the vibrating screen sieve, sports stadium track, crane shovel with dynamic oil seals, elevator wheels and roller skate wheels, polyurethane solid-core tires, photocopiers and screen printing squeegees and so on are also polyurethane elastomers are also the place to use. It should be mentioned that to increase the coefficient of friction of low and medium hardness polyurethane elastomer parts and to improve wear resistance under load, a small amount of lubricants such as aluminum disulfide, graphite or silicone oil can be added to these polyurethane elastomers.
Wide range of processing methods and applications
Cast polyurethane elastomers can be molded with general-purpose rubber as plasticizing, mixing, vulcanization process (MPU); can also be made into liquid rubber, pouring molding or spraying, potting, centrifugal molding (CPU); can also be made into granules, as with ordinary plastics, injection, extrusion, calendering, blow molding and other processes (TPU). Molded or injection molded parts, in a certain hardness range, can also be cut, grinding, drilling and other mechanical processing. The diversity of processing makes polyurethane elastomers very suitable for a wide range of applications.
Excellent physical and chemical properties
Oil resistance, ozone resistance, aging resistance, radiation resistance, low temperature resistance, good acoustic permeability, strong adhesion, excellent biocompatibility and blood compatibility These advantages are precisely the reason why polyurethane elastomers have been widely used in the fields of military, aerospace, acoustics and biology.
Improvement of high temperature resistance plus calcium carbonate and silica is the shortcomings of ester ammonia ester elastomers, but cast polyurethane elastomers are not perfect, its main disadvantages are:
1) endogenous heat, high temperature resistance performance is generally normal use of the temperature range is -40-120 ℃ use. If the need for high-frequency oscillation conditions or high-temperature conditions in the long-term role, it must be in the structural design or formulation to take corresponding modification measures.
2)Not resistant to strong polar solvents and strong acid and alkali media at a certain temperature, alcohols, acids, ketones will make the polyurethane elastomer swelling and degradation, chloroform, dichloromethane, dimethylformamide, trichloroethylene, and other solvents at room temperature will make the polyurethane elastomer swelling.
3) Its waste recycling is an international problem, and it is also a big problem for environmental pollution, because its waste treatment has not been attacked by a country in the international arena.