1、 Glass fiber is the mainstream reinforcing material, and technology drives the upgrading of product structure

1.1 As the mainstream reinforcement material, glass fiber can be applied in the downstream field

Glass fiber is a fiber reinforced material made of pyrophyllite, quartz sand, limestone and other minerals as raw materials, together with soda ash, boric acid and other chemical raw materials through high-temperature melting, drawing, winding, weaving and other processes; Compared with traditional metallic materials and non-metallic materials, glass fiber has the characteristics of high temperature resistance, corrosion resistance, high strength, light weight, small elongation and good electrical insulation. Glass fiber composite material is a functional material made by composite technology with glass fiber and its products (glass fiber yarn, cloth, felt, etc.) as reinforcing material and synthetic resin as matrix material; Glass fiber composite not only inherits the advantages of glass fiber itself, but also has the characteristics of energy saving, large design freedom, and wide adaptability. At present, the glass fiber category accounts for about 90% of the total reinforced fiber composite, and is widely used in construction, industrial pipe and tank, automobile and transportation, electronics and electricity, wind power and other fields.
The diversity of glass fiber determines the diversified development of glass fiber reinforced materials. At present, there are more than 5000 kinds of glass fiber applications in the world, and more than 60000 kinds of specifications and uses. The varieties and specifications are developing rapidly at an average annual growth rate of 1000-1500 kinds. The wide variety of glass fiber also determines the diversification of glass fiber reinforced materials. Glass fiber reinforced materials can be divided into glass fiber yarn reinforced composites and glass fiber felt reinforced composites according to the types of reinforced materials; According to the different matrix resins, it can be divided into glass fiber reinforced thermosetting composites and glass fiber reinforced thermoplastic composites. The glass fiber reinforced thermosetting composites are mainly based on thermosetting resins such as unsaturated polyester resin, epoxy resin, phenolic resin, vinyl ester resin, etc., and the thermoplastics are mainly based on polypropylene resin (PP) and polyamide (PA). The diversified glass fiber reinforced materials have different properties, laying a foundation for adapting to the needs of different fields.

Glass fiber reinforced composites have formed a complete industrial chain and are widely used. At present, the world's glass fiber industry has formed a complete industrial chain from glass fiber, glass fiber products to glass fiber composite materials. Its upstream industries involve mining, chemical industry, energy, and its downstream industries involve traditional industrial fields such as building materials, electronic and electrical equipment, rail transit, petrochemical industry, automobile manufacturing, as well as emerging fields such as aerospace, wind power generation, filtration and dust removal, environmental engineering, and marine engineering.

China's demand for glass fiber in the transportation sector accounts for 16%, which still has room for improvement compared with the global demand. According to OC statistics, the demand for glass fiber in the construction sector (including residential, commercial buildings, water storage and transportation, etc.) in the global glass fiber market will account for about 35% in 2020; Transportation (cars, trucks, buses, trains, navigation, etc.) accounts for about 26%, 15% in consumer fields such as electronic appliances, 13% in industrial fields (pipes and tanks, etc.), and 11% in wind power and energy fields. The domestic application of glass fiber is similar to that of the world, but the transportation sector accounts for 16%, which still has some room for improvement compared with the global proportion.

1.2 Technical upgrading improves material properties, and long glass fiber reinforced thermoplastic materials become the mainstream

From thermosetting to thermoplastic, from short glass fiber to long glass fiber, the application scenarios of glass fiber in the automotive field continue to expand. Since the advent of glass fiber in the 1930s, how to better use glass fiber in reinforced composites has become a hot issue. In the middle of the 20th century, people first compounded glass fiber with thermosetting resin, and introduced thermosetting composite materials represented by SMC, which can be used for automobile doors, bumpers and other parts. In 1972, people first used glass fiber felt as reinforcing material, and developed GMT (glass fiber felt reinforced thermoplastic material), which is mainly used for seat frame, car roof, engine protective cover, etc. In the 1990s, the introduction of long glass fiber thermoplastic material LFT expanded its application to the front end bracket, instrument panel, underbody cover, etc. At present, the technology of glass fiber reinforced materials has been greatly improved, and the application field has also been significantly expanded. Judging from the pace of technological development, the overall development trend of glass fiber reinforced materials: from glass fiber reinforced thermosetting composites to glass fiber reinforced thermoplastic composites, from short glass fiber reinforced composites to long glass fiber reinforced composites.

From thermosetting to thermoplastic

SMC materials open the door to the technological application of glass fiber reinforced materials. SMC is a glass fiber reinforced thermosetting composite, defined as a compressible, B-order sheet thermosetting composite, which is essentially a special form of prepreg. The earliest SMC formula used unsaturated polyester as the matrix resin, and later upgraded to choose vinyl ester resin with better performance but higher cost. Its performance is superior. The relative density (specific gravity) of glass is small, ranging from 1.6 to 2.0, which is lighter than the lightest metal aluminum; High specific strength, far higher than steel and cast iron. Compared with steel and cast iron, although the tensile strength is somewhat lower than that of steel, it has been equal to or even higher than that of cast iron, while the compressive strength and bending strength are close to that of steel.