Development and Application of Thermosetting Resin-based Composites

Composite material refers to a material composed of two or more different materials combined in different ways. It can exert the advantages of various materials, overcome the defects of a single material, and expand the application of the material. Due to its characteristics of light weight, high strength, convenient processing and molding, excellent elasticity, chemical resistance, and good weather resistance, composite materials have gradually replaced wood and metal alloys, and are widely used in aerospace, automotive, electronic and electrical, construction, and fitness equipment. In other fields, rapid development has been achieved in recent years.

With the development of science and technology, resins and glass fibers have continuously advanced in technology, and manufacturers’ manufacturing capabilities have generally improved. As a result, the price and cost of glass fiber reinforced composite materials have been accepted by many industries, but the strength of glass fiber reinforced composite materials is not sufficient. Comparing with metal. Therefore, carbon fiber, boron fiber and other reinforced composite materials have come out one after another, making the polymer composite family more complete, and it has become an indispensable material for many industries. At present, the annual production of composite materials in the world has reached more than 5.5 million tons, with an annual output value of more than 130 billion US dollars. If the high value products of military aviation and aerospace in Europe and the United States are included, the output value will be even more striking. From a global perspective, the production of composite materials in the world is mainly concentrated in Europe, America and East Asia. In recent years, the production and demand of composite materials in Europe and the United States have continued to grow, while Asia’s Japan has been slow to develop due to the economic downturn. However, the market in China, especially in Mainland China, has developed rapidly. According to statistics of PPG, the world's leading composite material manufacturer, in 2000, the global share of composite materials in Europe was about 32%, and the annual output was about 2 million tons. At the same time, the average annual growth rate of U.S. composite materials in the 1990s was about 2 times the U.S. GDP growth rate, reaching 4% to 6%. In 2000, the annual output of composite materials in the United States reached about 1.7 million tons. In particular, the rapid increase in composite materials for automobiles has led to the re-emergence of American cars in the global market. The development of composite materials in Asia in recent years has been closely related to the overall changes in the political economy. The share of countries varies greatly. Overall, Asia's composite materials will continue to grow. The total output in 2000 will be about 1.45 million tons. It is expected that the total output in 2005 will reach 1.8 million tons.

From an application perspective, composite materials are mainly used in the aerospace, automotive and other industries in the United States and Europe. In 2000, the use of composite materials for automotive parts in the United States reached 148,000 tons, and the amount of automotive composite materials in Europe was estimated to reach 105,000 tons in 2003. In Japan, composite materials are mainly used for residential construction, such as sanitary ware. The amount of such products used in the year 2000 reached 75,000 tons, and the use of automobiles and other fields was only 24,000 tons. However, from a global perspective, the automotive industry is the largest user of composite materials. The future development potential is still very large. There are still many new technologies being developed. For example, in order to reduce engine noise and increase the comfort of passenger cars, efforts are being made to develop two layers of vibration-reducing steel plates with thermoplastic resin interposed between cold-rolled plates; in order to meet the requirements of high-speed, supercharged, and high-loaded engines, engine pistons, Connecting rods and bushes have begun to use metal matrix composites. In order to meet the lightweight requirements of automobiles, more and more new composite materials will surely be applied to the automotive industry. At the same time, with the increasing emphasis on environmental protection issues in recent years, the application of polymer composite materials to replace wood has also been further promoted. For example, composite materials processed from plant fibers and waste plastics have been used extensively in North America as trays and packaging boxes to replace wood products, and degradable composite materials have become the focus of development research at home and abroad.

In addition, nanotechnology has gradually attracted people's attention, and the research and development of nanocomposites has also become a new hot spot. With nano-modified plastics, the aggregation and crystal morphology of plastics can be changed to give them new properties. While overcoming the inconsistencies in the rigidity and toughness of traditional materials, the comprehensive properties of materials are greatly improved.

Resin-based composite reinforcements

Reinforcing materials used in resin-based composite materials include glass fibers, carbon fibers, aramid fibers, ultra-high molecular weight polyethylene fibers, and the like.

1, glass fiber

At present, glass fibers used for high-performance composite materials mainly include high-strength glass fibers, quartz glass fibers, and high-silica glass fibers. Due to the high cost performance of high-strength glass fiber, the growth rate is also relatively fast, with an annual growth rate of more than 10%. High-strength glass fiber composite materials are not only used in military applications, but civilian products have also been widely used in recent years, such as bulletproof helmets, bulletproof clothing, helicopter wings, early warning aircraft radomes, various high-pressure pressure vessels, civilian aircraft straight bars, sporting goods, Various types of high temperature resistant products and recently reported tires with excellent performance. The quartz glass fiber and the high-silica glass fiber are high-temperature-resistant glass fibers, and they are ideal heat-resistant and fire-proof materials. The phenolic resin can be used to make various structural high-temperature and ablation-resistant composite material parts, and a large number of applications. Thermal materials for rockets and missiles. So far, among the three major reinforcing fibers of carbon fiber, aramid fiber, and high-strength glass fiber that have been practically used in China for high-performance resin-based composite materials, only high-strength glass fiber has reached the international advanced level and has independent intellectual property rights. A small-scale industry, with an annual output of up to 500 tons.

2, carbon fiber

Carbon fiber has a series of properties such as high strength, high modulus, high temperature resistance, and electrical conductivity. It has been widely used in the aerospace field and has been widely used in sports equipment and sporting goods in recent years. It is predicted that industrial-grade carbon fiber will be used on a large scale in the fields of civil construction, transportation, automobiles, and energy. From 1997 to 2000, the annual growth rate of aerospace carbon fiber was estimated at 31%, while the annual growth rate of industrial carbon fiber was estimated to reach 130%. The overall level of carbon fiber in our country is still relatively low, which is equivalent to the level of the middle and late period of the 1970s, and the gap with foreign countries is about 20 years. The main problems of domestic carbon fiber are that the performance is not stable and the dispersion coefficient is large, there is no high-performance carbon fiber, the type is single, the specifications are incomplete, the continuous length is not enough, there is no surface treatment, and the price is high.

3, aramid fiber

Since the 1980s, the Netherlands, Japan, and the former Soviet Union have also carried out the research and development of aramid fibers. Aramid fibers from Japan and Russia have been put into the market, and the annual growth rate has also reached about 20%. Aramid fiber has higher specific strength and specific modulus, so it is widely used in high-performance composite parts and components for aerospace applications (such as rocket engine housings, aircraft engine nacelles, fairings, rudders, etc.), and ships (such as aircraft carriers). , nuclear submarines, yachts, lifeboats, etc.), automobiles (such as tire cords, high pressure hoses, friction materials, high pressure cylinders, etc.), heat-resistant transport belts, sports equipment, etc.

4, ultra high molecular weight polyethylene fiber

The specific strength of UHMWPE fiber ranks first in all kinds of fibers, especially its excellent resistance to chemical attack and aging. It also has excellent high-frequency sonar permeability and seawater corrosion resistance, and many countries have used it to manufacture high-frequency sonar flow shields for ships, which greatly improves the detection and removal capabilities of warships. In addition to military fields, ultra-high-molecular-weight polyethylene fibers in automotive manufacturing, shipbuilding, medical equipment, sports equipment and other fields also have broad application prospects. Once the fiber came out, it attracted great interest and attention from developed countries in the world.

5, thermosetting resin matrix composites

Thermosetting resin matrix composites refer to thermosetting resins such as unsaturated polyester resins, epoxy resins, phenolic resins, vinyl ester resins, etc., and glass fibers, carbon fibers, aramid fibers, ultra-high molecular weight polyethylene fibers, and the like. Reinforced material made of composite materials. Epoxy resin is characterized by excellent chemical stability, electrical insulation, corrosion resistance, good adhesion and high mechanical strength, widely used in chemical, light industry, machinery, electronics, water conservancy, transportation, automotive , home appliances and aerospace and other fields. In 1993, the world's epoxy resin production capacity was 1.3 million tons, which was increased to 1.43 million tons in 1996, 1.48 million tons in 1997, 1.5 million tons in 1999, and 1.8 million tons in 2003. China began to study epoxy resin in 1975. According to incomplete statistics, there are currently more than 170 epoxy resin manufacturers in China, with a total production capacity of more than 500,000 tons, and the utilization rate of equipment is about 80%. Phenolic resin has the characteristics of heat resistance, abrasion resistance, high mechanical strength, excellent electrical insulation, low smoke and acid resistance, and is widely used in various fields of composite materials industry. In 1997, the global output of phenolic resin was 3 million tons, of which the United States was 1.64 million tons. China's output is 180,000 tons and imports 40,000 tons. Vinyl ester resin is a new type of thermosetting resin developed in the 1960s. It is characterized by good corrosion resistance, good solvent resistance, high mechanical strength, high elongation, and adhesion to metals, plastics, concrete, and other materials. Good performance, good fatigue resistance, good electrical properties, heat aging, low cure shrinkage, cure at room temperature, or heat cure. Nanjing Jinling DSM Resins Co., Ltd. introduced Dutch Atlac series strong corrosion-resistant vinyl ester resin, which has been widely used in storage tanks, containers, pipelines, etc. Some varieties can also be used for waterproofing and hot press molding. Nanjing Julong Composite Materials Co., Ltd., Shanghai Xinhua Resin Factory, Nantong Mingjia Polymer Co., Ltd. and other manufacturers also produce vinyl ester resins.

Before 1971, China's thermosetting resin-based composites industry was mainly military products. Since the 1970s, it began to turn to civil use. Since 1987, a large number of foreign advanced technologies have been introduced from various places, such as the drawing of the kiln and kiln, chopped strand mats, surface felt production lines, and various grades of polyester resins (US, German, Dutch, English, Italian, and Japanese) and epoxy resins. , German) production technology; in the molding process, the introduction of the winding pipe, tank production line, pultrusion process production line, SMC production line, continuous board unit, resin transfer molding (RTM) molding machine, injection molding technology, resin injection molding technology And the fishing rod production line formed a complete industrial system from research, design, production, and raw material support. By the end of 2000, there were more than 3,000 thermosetting resin-based composite material production enterprises in China and 51 of them had passed ISO9000 quality system certification. With more than 3,000 product varieties, the total output reaches 730,000 tons/year, ranking the second in the world. The products are mainly used in construction, anti-corrosion, light industry, transportation, shipbuilding and other industrial fields. In terms of construction, there are interior and exterior wall panels, transparent tiles, cooling towers, air-conditioning hoods, fans, fiberglass tanks, sanitary ware, septic tanks, etc.; in the petrochemical industry, it is mainly used for pipelines and storage tanks; in transportation, on the car Mainly there are bodywork, hoods, bumpers and other accessories. There are cabin boards, doors and windows, and seats on the trains. There are mainly hovercrafts, lifeboats, scout boats, and fishing boats on the trains; in the mechanical and electrical fields such as roof fans and axial flow. Fans, cable trays, insulated rods, integrated circuit boards and other products have considerable scale; in the aerospace and military fields, light aircraft, tail fins, satellite antennas, rocket nozzles, bullet-proof panels, body armor, and torpedoes have achieved significant breakthrough.

Thermoplastic resin matrix composites

Thermoplastic resin matrix composites were developed in the 1980s and consist mainly of long fiber reinforced pellets (LFP), continuous fiber reinforced prepreg tapes (MITT) and glass fiber mat reinforced thermoplastic composites (GMT). According to different requirements, the resin matrix mainly includes thermoplastic engineering plastics such as PP, PE, PA, PBT, PEI, PC, PES, PEEK, PI, and PAI. The fiber types include glass fiber, carbon fiber, aramid fiber, and boron fiber. The fiber variety. With the continuous maturity of thermoplastic resin matrix composites technology and the advantages of recyclability, this type of composite material has developed rapidly. Thermoplastic resin matrix composites in Europe and America have accounted for more than 30% of the total amount of resin matrix composite materials.

High-performance thermoplastic resin matrix composites are mostly injections, and the main body is PP and PA. Products include pipe fittings (elbows, tees, flanges), valves, impellers, bearings, electrical and automotive parts, extruded pipes, GMT molded products (such as jeep seats), car pedals, and seats. Glass fiber reinforced polypropylene applications in automobiles include ventilation and heating systems, air filter housings, transmission covers, seat frames, fender gaskets, drive belt guards, and more.

Talc-filled PP has high rigidity, high strength, excellent heat aging resistance and cold resistance. Talcum powder reinforced PP has important applications in interior decoration, such as ventilation system parts, instrument panel and automatic brake control bar, etc. For example, the sound absorption of cellular structure made by HPM, which is filled with PP with 20% talcum powder. Ceiling lifter and car's window lifter rope drum shell.

Mica composite material has high rigidity, high heat distortion temperature, low shrinkage, low flexibility, dimensional stability, low density, low price and other characteristics. It can make car dashboard, headlight protection ring, and block using mica/polypropylene composite material. Parts such as panel covers, door guardrails, motor fans, shutters, etc., utilize the damping properties of the material to produce audio components, and use their shielding properties to create battery boxes.

The research of thermoplastic resin matrix composites in China began in the late 1980s and has achieved rapid development in the last decade. In 2000, the output reached 120,000 tons, accounting for about 17% of the total output of resin-based composite materials. It is still mainly based on PP and PA. The reinforcing material is mainly glass fiber, and a small amount is carbon fiber. There is no major breakthrough in thermoplastic composite materials, and there is still a gap with developed countries.

The development potential and hot spots of China's composite materials

The potential for the development of composite materials in China is great, but the following hot issues must be addressed.

1. Composite Material Innovation

Composite materials innovation includes technology development of composite materials, process development of composite materials, product development of composite materials, and application of composite materials. Specifically, it is necessary to grasp the development and innovation of resin matrices, innovation in the development of reinforced materials, innovation in the production process, and innovation in the development of product applications. . By 2007, Asia’s share of the world’s total sales of composite materials will increase from 18% to 25%. At present, Asian per capita consumption is only 0.29kg, compared with 6.8kg in the United States, and Asia has great growth potential.

2, acrylonitrile-based fiber development

China's carbon fiber industry is developing slowly. From the CF development review, characteristics, domestic carbon fiber development process, China's PAN-based CF market profile, characteristics, and the "Tenth Five-Year Plan" scientific and technological breakthroughs, the development of PAN-based fibers is both necessary and possible.

3, glass fiber structure adjustment

More than 70% of China's glass fiber is used for reinforcing substrates, which has a cost advantage in the international market. However, there is still a gap between the specifications and quality of the fiberglass and advanced countries. It is necessary to improve and develop yarns, wovens, nonwovens, and braids. , sewing fabrics, composite felts, promote the close cooperation between glass fiber and glass steel industry, and promote the new development of glass fiber reinforced materials.

4. Development of composite materials market for energy and transportation

The first is composite materials for clean and renewable energy, including composite materials for wind power generation, composite materials for flue gas desulphurization devices, composite materials for power transmission and transformation equipment, and high pressure vessels for natural gas and hydrogen; second, composite materials for automobiles and urban rail transit. , Including automotive body, frame and exterior body coverings, rail transit body, doors, seats, cable ducts, cable racks, grilles, electrical boxes, etc.; Third, civil aviation passenger aircraft composite materials, mainly carbon fiber composite materials. About 10% of thermoplastic composite materials, the main products for the wing components, vertical tail, head cover and so on. In the next 20 years, China will need to add 661 new regional aircraft, which will form a large industry for civil aviation passenger planes. Composite materials can be built into new industries to support them. Fourth, composite materials for boats, mainly yachts and fishing boats, and yachts as advanced entertainment and durable Consumer products have a large market in Europe and the United States. Due to the reduction of fish resources in China and the slow development of fishing boats, the unique advantages of composite materials still have room for development.

5, fiber composite material infrastructure applications

Composite materials at home and abroad are widely used in bridges, houses, and roads. Compared with traditional materials, composite materials have many advantages, especially in bridges, and in housing reinforcement, tunnel construction, and repair and consolidation of large warehouses.

6, comprehensive treatment and regeneration of composite materials

Focus on the development of physical recycling (crush recovery), chemical recovery (thermal cracking) and energy recovery, strengthening of technical routes, comprehensive treatment technology research, demonstration of production line construction, recycling utilization research, vigorously expanding the application of recycled materials in gypsum, in pultrusion Applications in Products and Applications in SMC/BMC Molded Products and Typical Products.

The 21st century high-performance resin-based composite material technology is an intelligent material that gives self-repairing, self-decomposition, self-diagnosis, and self-made functions to composite materials. The company focused on the development of composite materials used in high-rigidity, high-strength, and high-humid-heat environments to construct a material system that integrates materials, molding, processing, design, and inspection. The organization system will be alliance and grouping, which will make full use of various resources (technical resources, material resources) and closely link the advantages of various parties to promote the further development of the composite materials industry.

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