It has been more than 60 years since the birth of FRP. It has developed from simple hand lay-up process to today’s computer-controlled operation. Our products have different performances and varieties, which are all over our life.
II. Raw materials of FRP
I) Glass fiber
- Glass fiber is made of glass, which is pulled down in high temperature melting state. Its diameter is generally 0.5-30 μ m, and its surface is treated with coupling agent, which improves the adhesion with resin. It is a reinforced material in FRP, mainly providing strength.
- Classification, performance and products
According to the chemical composition, it can be divided into non alkali, medium alkali and high alkali glass fibers, which are expressed by E, C and a respectively. E glass has high strength, alkali resistance, water resistance, heat resistance, good electrical insulation and poor acid resistance. C glass a glass has better acid resistance, but other properties are not as good as E glass. The specific gravity of glass fiber is about 2.5. The surface felt, chopped felt, winding yarn and alkali free cloth used by our company belong to e glass.
1) winding yarn
According to the production process, it can be divided into direct yarn and indirect yarn (composite yarn)
Model: 1200tex, 2400tex, 4800tex. Tex: 1000 m single strand yarn weight.
2) chopped felt: it is made of 50-70mm short fiber. Common specification: 300g / m2450g / m2
3) knitted felt: common specifications: 380g / m2, 450g / m2
4) glass fiber cloth: the unique production process of glass fiber surface felt determines that it has the characteristics of smooth surface, uniform fiber dispersion, smooth handle, good air permeability and fast resin penetration. The surface felt is used for FRP products. Its good air permeability can make the resin penetrate quickly and eliminate bubbles and white stains completely. Its good formability is suitable for any kind of complex products and molded products. It can cover the cloth grain, improve the surface finish and leakproofness. At the same time, it can enhance the interlaminar shear strength and surface toughness, and improve the corrosion resistance and weather resistance of the products It is necessary for making high partial strand FRP mould and products. The products are suitable for FRP hand lay up, winding, pultrusion, continuous plate, vacuum absorption molding and other processes.
Neutral alkali cloth — 0.2:180g / m2; 0.4:360g / m2
Alkali free cloth — 0.4:400g / m2; 0.6:570g / m2, etc
5) surface felt: as above
Specification: 30g / m2, 50g / m2
Resin is the matrix material in FRP, its function is to transfer force load between fibers, it determines the heat resistance, corrosion resistance and aging resistance of FRP. There are two kinds of resins: thermoplastic and thermosetting. The commonly used FRP is produced by thermosetting resin. The so-called thermosetting resin refers to the formation of insoluble and insoluble materials after curing. If the temperature is too high, it will break down. Commonly used are unsaturated polyester resin, epoxy resin, phenolic resin. This paper mainly introduces unsaturated polyester resin.
- Classification of unsaturated polyester resin
The classification of unsaturated polyester resin is generally divided into general type, heat-resistant type, chemical resistant type, light stable type, self extinguishing type and sewing type. According to the chemical composition, it can be divided into ortho benzene type, m-benzene type, bisphenol a type and vinyl type.
Among the commonly used brands, 192a and p65-90119119886 belong to o-benzene resin, which is mostly used for structural fabrication; 2028972 belongs to m-benzene type, which can be used as lining or structural layer: 9503 is p-benzene type; 3301197382941 belongs to bisphenol a type, which is used for lining fabrication, which is used for places with high requirements of chemical corrosion resistance; 470430590.3201, MFE-2 and w2-1 belong to vinyl type or improved type C-type resin, used for chemical corrosion resistance, higher temperature requirements. 2028382976a belongs to food grade resin, which is used to make FRP pipes or containers for conveying or storing tap water or food.
III) Auxiliary materials
Colorant (pigment), wear-resistant agent (quartz powder, diamond powder, etc.), flame retardant (halide), quartz sand with increased rigidity, antistatic agent (graphite), etc.