With the development of the automotive industry, the demand for fiber reinforced thermoplastics has increased significantly, and its manufacturing process technology has entered a period of rapid development. Such as direct (online) compound long fiber reinforced thermoplastic (D-LFT), mold cavity induction heating for improving the surface quality of long fiber reinforced thermoplastic (LFT) molded parts, LFT masterbatch, ring-based polyester New technologies such as in-situ polymerized fiber reinforced composites, LFT-specific glass fibers and surface sizing agents continue to emerge. A review of these latest process technologies is provided for the development of automotive fiber reinforced thermoplastics. Fiber reinforced plastic (FRP) has developed rapidly with the development of the automotive industry. In particular, fiber reinforced thermoplastics, because of their good recyclability, are easy to recycle and develop circular economy, and become the focus and direction of the development of automotive plastics. Among fiber-reinforced thermoplastics, the development of long-fiber reinforced thermoplastics (LFT) is the most striking. While the demand for LFT is growing rapidly, the process technology for automotive fiber reinforced thermoplastics has also made great strides. Further development of direct (online) batching LFT (D-LFT) process technology, long fiber reinforced masterbatch technology, and improved long fiber reinforced thermoplastic molding process from fiber felt reinforced thermoplastic composite sheets (GMT) and LFT Rapid change of mold surface temperature technology, in-situ polymerization technology based on ring-shaped polyester-based fiber reinforced thermoplastic matrix, special fiberglass and surface treatment technology for long fiber reinforced thermoplastics. 1 D-LFT process technology Compared to the use of long fiber reinforced thermoplastic pellets (LFT-G), the D-LFT process has several outstanding advantages: Integrating the ingredients with the molding, eliminating the preparation of the prepreg and saving manpower; Less heat generation, no secondary melt plasticization, energy saving; To avoid the influence of the secondary melt plasticization process on the resin and the long fiber, without excessively damaging the added fiber, the performance of the resin matrix and the fiber length can be higher than that of the LFT-G molding, and the average fiber length ratio is LFT-G. The molding is 15%-20% higher, with high quality product performance. Through the optimization of product and mold design and process conditions, the mechanical properties of the product can be close to GMT products; The process and production cycle are shortened, and the production efficiency is low. The production cost can be reduced by about 40% compared to the long fiber pellets. The D-LFT process was pioneered by Woodshed Technologies. In 2005, Plastic Comp received its Pushtrusion production technology license. In recent years, Pushtrusion has been continuously developed and improved. The basic process principle is: supplying a thermoplastic resin melt to the coated impregnation die through an extruder, and then coating the long fiber with a high pressure melt and dragging it to the cutter at the end of the impregnation die, the cutter is set according to the prior The length cuts the long fibers coated in the melt, and the melt is injected into an injection molding machine for injection molding. Based on the Pushtrusion D-LFT, Plastic Comp has developed a direct in-line compounding molding process to directly transfer the prepared long fiber and molten resin composite into a press molding machine to form the final product without using prefabricated GMT sheets. It is also called Pushtrusion D-GMT. Pushtrusion D-GMT provides great flexibility for processors to produce long fiber reinforced plastic products, especially for resin and fiber varieties, pigments and other additives, and is no longer subject to supplier constraints. Engel and Krauss Maffei use a combination of co-rotating twin-screw extruders and injection molding machines to combine continuous extrusion with injection molding cycles to create a highly efficient long-fiber reinforced thermoplastic in-line batch injection molding system. The system can also operate independently if necessary. Husky's single-spindle rod extruder and injection molding machine with a special configuration form an online batch injection molding system. A squeegee is placed in the low pressure venting zone of the extruder and at the fiber inlet, and a scraper is mounted. Its scraping motion on the screw improves the melt delivery of these low pressure zones in the extruder. Dow uses a twin-screw extruder for in-line dosing. The thermoplastic resin and additives are melt-kneaded and plasticized by a twin-screw extruder. The continuous fiber yarn is introduced downstream of the twin-screw extruder, and the composite is formed through the extruder head. The continuous extrudate of shape is cut by a cutter and then directly sent into a molding machine to form a product. 2 mold cavity surface temperature rapid conversion technology In order to expand the application range of fiber reinforced thermoplastics to the automotive exterior parts with high surface quality requirements, the surface temperature of the mold in contact with the melt is kept above the glass transition temperature of the matrix resin or even close to the melt during the injection. Temperature, it is obvious that it is easy to obtain a product of high surface quality. However, the thermoplastic article must in turn be cooled to a temperature below the heat distortion temperature, and normal mold cooling is still necessary. In order to improve the molding process of fiber reinforced thermoplastics, rapidly changing the surface temperature of the mold cavity becomes the key to solving the problem. The latest mold induction heating technology meets this fast change requirement. In order to achieve a rapid change in the surface temperature of the mold cavity, Roc-tool has proposed a solution for mold induction heating. With electromagnetic induction technology, the ideal melt rheology condition is obtained by rapidly heating the mold surface to a temperature close to the injection plastic melt. The resin is at a temperature close to the surface of the mold and the flow is very easy. In order to be used more widely in a variety of different applications, Roc-tool combines its partner Wittmann Battenfeld's Indumold technology in its mold cavity induction heating technology to introduce two types of mold induction heating systems, namely cages. The system is integrated with a built-in Sensor inside the mold. Induction heating technology was successfully applied to LFT plastic injection molding and compression molding dies to produce large automotive parts with Class A surfaces. Roc-tool's patented method only heats and cools the mold cavity surface, and its cycle time is much faster than conventional methods. Turning on the sensor power supply takes only a few seconds to several tens of seconds to heat up. The heating depth is only in the surface layer of 0.2mm below the surface of the mold. 99.9% of the total mold is not heated. Roc-tool can also design different conductive materials for the mold surface layer, so that the temperature of some parts of the mold is higher than other parts, so that the product can reach the A-level surface requirement only in a certain area. 3 long fiber masterbatch In order to produce LFT products more conveniently and economically, and effectively improve the performance of LFT products. RTP, Dow, etc. have developed long fiber masterbatches to enable product manufacturers to flexibly adapt to the production needs of LFT products. RTP's long-fiber masterbatch has a glass fiber mass fraction of 60% to 75%, which can be used by diluting it with pure resin in the required proportion during molding. The masterbatch fiber has a length of 12 mm and can also be customized in the range of 8-25 mm. The long fiber masterbatch developed by Dow is completed in two steps. That is, the additive masterbatch is first prepared, and its composition (parts by mass, the same below) is 70 parts of polypropylene (Borflow HL504FB), 15 parts of carbon black, 6.7 parts of 168 antioxidants, 3.3 parts of 1010 antioxidants, and PS802 antioxidants 5.0. Share. The additive masterbatch is then extruded through an extruder together with a polypropylene carrier, a dispersant, a modifier, etc., and the continuous glass fiber is impregnated through an impregnation die, and the long fiber masterbatch is obtained by pultrusion, cooling, and pelletizing. The composition of the masterbatch was 32.4 parts of polypropylene (H734-52RNA), 4.0 parts of polypropylene (Borflow HL504FB), 2.1 parts of additive mother particles, 60.0 parts of glass fibers, and 1.5 parts of polymer coupling agent. Here, the melt flow rate of the commercial brand No. Borflow HL504FB polypropylene is 450 g/10 min, and the melt flow rate of the commercial brand H734-52 RNA polypropylene is 52 g/10 min. The latter is an injection molding grade material with high fluidity and good balance between physical properties, while the former has a very low viscosity, which is favorable for the matrix resin to infiltrate the glass fiber well. 4 new raw material technology The most revolutionary in the field of automotive fiber reinforced thermoplastics is fiber reinforced thermoplastics based on in-situ polymerization of ring-shaped polyester (CBT). CBT is a mixture of different low molecular weight oligoesters with a macrocyclic structure produced by the Cyclics patent of the United States. CBT is added to the tin catalyst during processing and is ring-opened to linear polybutylene terephthalate (PBT) at a suitable temperature. The relative molecular mass is twice that of the general PBT resin. With outstanding processing advantages, extremely low viscosity enables fast and excellent wetting of fiber reinforced materials, and can be molded at very low pressure for rapid polymerization; almost all fiber composites of thermoplastic and thermosetting resins can be used. The material is processed by molding (and usually the method is simple). In addition, the polymerized material in turn has reproducible thermoplastic characteristics of conventional PBT resins. In addition, in order to meet the requirements of the process and product performance of glass fiber yarn for LFT, and to solve the problem of wettability on the surface of long fibers, OCV, PPG Industries, and Saint-Gobain of France are all engaged in the development of special sizing agents. PPG Industries uses a maleic anhydride, polyethylene glycol or polypropylene glycol, fatty acid glycidyl ester and rosin resin to carry out a stepwise reaction to obtain modified rosin, and then with A174, A187, A1100 coupling agent, and pH regulator, A lubricant, an antifoaming agent, water, etc. are used as an sizing agent. The sizing agent has the outstanding advantages of exhibiting good strand bundling in fiber production, improving the frictional properties of the fiber, reducing the breakage of the monofilament in the production process of the glass fiber strand, and facilitating the consistency of the product, and Reduce the production cost of fiber raw silk, improve the scratch resistance in the subsequent processing, reduce the breakage of monofilament in the subsequent process, improve the production efficiency of the subsequent process; adapt to a variety of resins, a variety of reinforced plastic manufacturing processes Wait. 5 Conclusion Fiber-reinforced thermoplastics are gaining more and more applications in the automotive industry. The development of process technology is changing with each passing day, especially LFT and D-LFT. Foreign countries have formed a complete industry from raw materials, equipment and molds. Chain, technology is maturing. However, these aspects of domestic work have just started, and there is still a lack of in-depth research and development. It is hoped that it will attract the attention of domestic counterparts, strengthen the research and development of process technology for automotive fiber reinforced thermoplastics, and promote the common development of the automotive industry and the plastics industry. Aluminum Sliding Door,Sliding Door Philippines Price,Sliding Door Price,Sliding Door Philippines Caesar door control co.,ltd , https://www.caesar-door.com
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