The most popular new materials for variable fiber

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New material for variable fiber injection molding

polyurethane industry new material for variable fiber injection molding Zhang Yuedong 2 (1. Huntsman polyurethane (USA) (2. Huntsman polyurethane (China) Shanghai) technology manufactures SRIM polyurethane products. The characteristic is that before polyurethane is injected into the mold, it is first soaked and mixed with the directly added chopped fiber in the mixing cavity, reducing the processing process of fiber felt pads, It can also improve the content of cellulose in products. With this method, up to 50% glass fiber can be added, and the product density ranges from 0.5g/cm3 to 1.6g/cm3, with a high bending modulus. Due to the chemical diversity of polyurethane polymers, structural reaction injection molding (SRIM) - polyurethane is always used as the main basic polymer material. In 2013, the net profit of BOE, which has a low profit all year round, also reached 2.25 billion yuan (2) 350 million yuan. To some extent, this technology has been considered as a mature technology. Due to the integration of various industries, the demand for light automotive components and the competition between selective polymers, people continue to reduce the comprehensive cost of such products. This trend puts forward new requirements for the development of new technologies to meet the economic needs and the requirements of automotive component products for material physical properties. For polyurethane SRIM, the traditional reinforcement method is to put the glass fiber pad into the mold first, and then inject liquid resin. The disadvantages of this process are the prefabrication and placement of glass fiber felt, and the addition of glass fiber is limited. The reason is that when the amount of glass fiber is increased, the fluidity of the resin becomes poor, and small bubbles will wrap in the system. In recent years, polyurethane equipment manufacturers have developed variable fiber injection processing technology in order to seek the feasibility of overcoming this limitation. The processing method is to infiltrate and mix with directly added chopped fibers in the mixing cavity before polyurethane is injected into the mold. The advantage of manufacturing SRIM synthetic materials by this method is that it reduces the past processing procedures and can also improve the content of fiber in products. The combination of variable fiber injection technology and polyurethane chemical diversity enables people to manufacture synthetic materials that meet a variety of performance requirements. Using this method to manufacture synthetic materials, we can have higher density and wider adjustable range of fiber content, so the components made have a wide adjustable range of performance. The following will focus on this processing technology and the physical properties that can be achieved by using fibrim technology. Variable fiber injection technology has opened up a new way for the production of polyurethane materials on behalf of the imported variable fiber injection technology. Although each manufacturer's technology has its own characteristics, it still has common basic characteristics. The basic configuration of polyurethane variable fiber injection processing is: metering pump, mixing head, fiber chopper, and automatic mechanical parts (). The fiber roving is input into the chopper, cut into scattered short fibers, and enter the mixing chamber at the same time. This mixing head is an improved version of the standard polyurethane mixing head. Fibers can be conveyed from the top of the L-shaped mixing head to the mixing chamber (see). There is usually a solid self-cleaning piston located in the cavity. The fiber is mixed with polyurethane liquid and flows to the lower part of the mixing chamber. Then, the mixture of fiber and polyurethane leaves the mixing head and is injected into the mold. One of the characteristics of fiber chopper is that it can control the length, density and quantity of fiber roving. The length of the cut fibers can be changed by changing the spacing of the chopper blades, for example, long fibers can be cut. Some choppers can drive a variety of knife wheels with different intervals to cut fibers of different lengths and inject them into molds. At the same time of pouring, the speed of the crusher can be changed to a certain extent through program control. Chebayer integrated 150 proposals to report. With the cooperation of mechanical casting hands, the distribution of fibers in the whole product can be well controlled. Variable fiber injection technology can be applied to a variety of production occasions. For example, automatic foaming units with improved mixing heads and fiber shredders can produce a variety of complex molded products. By optimizing the pouring mode, it can meet the requirements of various manufacturers to manufacture products of various shapes. Another advantage of this technology is its processing economy. It is estimated that the cost of fiber roving is 60% lower than that of glass fiber mats used in the traditional SRM process; As the labor force for placing the fiber pad into the mold is reduced, the cost is also reduced; When pouring glass fiber resin mixture, due to precise control, waste can be reduced. Therefore, the combination of these factors reduces the whole production cost, which is the main advantage of this technology. 0.5g/cm3 to 1.6g/cm3 Similarly, in the components produced, the mass fraction of glass fiber can range from a few percent to more than 50%. By choosing appropriate polyurethane formula, the physical properties of products can meet or even exceed the properties of many special materials at present. Due to the general adjustability of components and fiber content, designers can use this technology to develop automotive internal and external components, structural parts and non structural parts. The applied products produced by this technology include door panels, luggage trays and the shells of light trucks. 2fiberim resin is easy to protect. Mai polyurethane company has produced a polyurethane raw material system with fibrim as the trademark for variable length fiber reinforced reaction injection molding products. This kind of material has low cost, can replace the traditional SRM technology, and is suitable for the production of a variety of parts in transportation vehicles. SRIM components that have been or are trying to be produced with fibrim technology and resin include door panels, cushion trays, bumpers, sun visors, car luggage trays, and light truck box panels. These products have different functions, and their physical property requirements are also different. Table 1 shows the performance comparison of low density SRM (lehsrm) door panels produced by fibrim technology and traditional fiber pad insertion technology. Table 1 Comparison of processing methods and glass fiber length using fiberim technology and traditional technology li>srim physical properties traditional glass fiber felt mat glass fiber mass fraction/bending modulus/mpa tensile strength/mpa product, its physical properties are equivalent to those of traditional methods. The content of glass fiber will greatly affect the performance of products. With new technology, the bending modulus and tensile strength will also increase with the increase of fiber addition. For higher application requirements, such as manufacturing cushion trays and other structural panels, high-density products can be obtained by changing the composition of polyurethane formula and water content. The physical properties of high-density fiberin system products are listed in Table 2. Table 2 Comparison of physical properties between fibrim and traditional high-density composites processing methods traditional methods glass fiber length/mm felt mat glass fiber mass fraction/bending modulus/mpa tensile strength/mpa note: the mass ratio of 12.5mm and 25mm glass fibers is 2. Under the conditions of similar density and the same amount of glass fiber, fibrim samples show excellent physical strength compared with SRIM products reinforced by traditional glass fiber felt mats. By increasing the density of polyurethane (and the amount of glass fiber added), it can be found that the bending modulus and tensile strength increase. 3 conclusion as mentioned above, the diversity of polyurethane chemistry and variable fiber injection through variable fiber injection technology and polyurethane polymer diversity technology make this technology can be applied in many fields. The combination of hengish and s can produce automobile parts with a wide range of applications. Use

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