Polyurethane materials [that is, high molecular polymers containing urethane groups and -NHCOO in the main chain of macromolecules] have developed rapidly since the industrial production was not released on the market in the 1950s. Compared with polymer rubber materials, it has its own unique characteristics. It can use different numbers of functional groups and different types of functional groups according to different performance requirements, and use different production processes to produce polyurethane products with different properties and properties.
Among rubber rubber types, there are polyurethane rubber varieties that can be cross-linked. There are also those that are not in the category of rubber, such as foam plastics, rigid plastic products, coatings, high resilience synthetic fibers, artificial leather, adhesives, and so on.
Polyurethane materials are currently widely used in various fields. For example, in the aerospace industry, its hard products, soft products, and foam products are lighter than metal materials, [very important for aircraft], and have high resilience and non-flammability. , High-strength, ultra-low temperature insulation, etc., used for aircraft hoods, speed brakes, radomes, aircraft fuel tank fillers, fuel consumption control vaporizer buoys, etc., as well as various support frames and seat cushions for internal decoration. It is used for heat preservation in the transportation industry. Polyurethane materials are inseparable from materials and seat cushions, home furnishing manufacturing, and even high-end adult condoms, and tires. And the recent development and use of products in automotive shock absorption and damping accessories have attracted more attention.
Although there are many types of polyurethane products, the classification of its products is nothing more than:
Flexible foam products, rigid products, and elastomers [thermoplastic elastomers, vulcanizable elastomers EU, AU]. The product molding equipment, such as mixing polyurethane rubber, is generally solid and can be vulcanized with sulfur, peroxide, and polyisocyanate. It can be designed according to the conventional rubber product production process and formula. If it is a thermoplastic elastomer, it can be injection or compression molding. If it is a plastic polyurethane, it can be produced by a casting method.Taking flexible polyurethane foam products as an example, the composition of the formula, the main reactants of which are polyether, polyester, or other polyols; and polyisocyanates. Others include water [chain extender], crosslinking agent, catalyst, foam stabilizer, external blowing agent, flame retardant, mold release agent, coloring agent, etc. The production process is generally two-component liquid reaction molding. That is to say, one group is that the polyol polymer and the isocyanate are mixed and reacted first, and then the above reactants are mixed with another group including water, blowing agent, stabilizer, catalyst, and various auxiliary agents to produce organic carbamate. At the same time, the reactants such as urea group use the reaction to generate carbon dioxide, release a large amount of heat, vaporize the added blowing agent, and then use the catalyst to adjust the foaming speed, and finally complete the product with uniform foam structure. At present, the automobile manufacturing industry has continuously improved safety, comfort, and durability, and has high requirements for durability in high-strength working conditions of shock-absorbing and damping elastomer parts. A new type of shock absorber made of polyurethane flexible foam has appeared in foreign markets. Its physical and mechanical properties and damping effect are slightly better than rubber damping accessories. The product requires a density of 0.08g 丿cm3, a material compression of 5%, a compressive strength of more than 7Kpa, the product works normally at -20-40 "degrees", the product's compression set is not more than 10%, and it has oil resistance. Under pressure impact, no fracture occurs. The production process is not special. The key lies in its main reaction material. Currently, BASF is monopolizing the production and supply. BASF also learns from DuPont's market supply principle of perfluoroether rubber, which is to sell only finished products, not raw materials. , In order to achieve the reduction of market competitors.
This new type of polyurethane flexible foam automobile shock-absorbing parts adopts an advanced "one-step" molding process, that is, all components of the raw materials in the formulation, such as isocyanate, polyol polymer, chain extender, catalyst, foam stabilizer and others The auxiliary agent is measured according to the formula, with isocyanate as a separate component, and various auxiliary agents such as polyol polymer, water, auxiliary blowing agent, chain extender, surfactant, catalyst, etc. are pre-prepared into one component, and then once Add it to the reaction tank and add the foaming agent afterwards. After high-speed stirring and mixing, the foaming reaction process is carried out. This one-step production process is particularly suitable for processing accessories with complex shapes and small specifications. In the molding method, the mixed liquid is directly injected into a mold with a complicated shape, and then foamed in the mold cavity for forming. Products made by this method. The specifications and dimensions are accurate, and it can also be used as metal inlaid products according to needs.
Polyurethane products are currently widely used and the market demand is also large. Although my country started late, it has developed rapidly. Its global market share has reached more than a quarter. It has become the world's largest manufacturing and consumer market for polyurethane products. However, there is still a gap between the key main reaction materials and the advanced foreign level, and the industry needs to work hard to innovate and develop.It is reported that retreading tires with polyurethane material as tread rubber has better wear resistance and environmental protection than natural rubber. This innovative research and development has opened up a new way for retreading. During the "13th Five-Year Plan" period, the polyurethane industry will have more room for development.
