Glass fiber production process and application

2018-11-30 09:35

. Glass fiber is light in weight and high in application.


Glass fiber was born in the 1930s. It is an inorganic non-metallic material produced from the main mineral raw materials such as pyrophyllite, quartz sand, limestone, dolomite, bauxite, and boehmite, and chemical raw materials such as boric acid and soda ash. Glass fiber has the advantages of high mechanical strength, high impact energy absorption, high heat resistance and good corrosion resistance, and is generally used as a reinforcing material in composite materials.


The production process of glass fiber is 坩埚 drawing method and pool kiln drawing method. At present, the drawing ratio of pool kiln in China is about 94%. The wire drawing machine is the key equipment in the glass fiber forming process. Its function is to stretch the glass liquid flowing out of the leakage plate at high speed and wind it in a certain direction. The performance and precision of the wire drawing machine directly affect the quality of the fiber.




Due to its light weight, high strength, high temperature resistance, corrosion resistance, heat insulation, flame retardant, sound absorption, electrical insulation and other functional properties, glass fiber reinforced plastics gradually replace steel and aluminum in many application fields. Traditional materials such as wood have developed into functional and structural reinforcement materials for general use, and thus have achieved large-scale applications in transportation, construction, electronics, plumbing, chemical, environmental protection, and defense and military industries.




Glass fiber industry chain: Compared with downstream composite materials enterprises, upstream raw material enterprises have high homogeneity, high concentration and periodicity. Glass fiber reinforced plastics are mainly used in the automotive, construction and electrical and electronic fields. The applications in the automotive and construction sectors account for about one-third of the total applications, and the electrical and electronic applications account for about 15%.






The glass fiber yarn is divided into fine yarn and roving according to the diameter of the monofilament, and the spun yarn is used for electronic and industrial, and the roving is further processed:


Spinning yarn, which refers to yarns with a monofilament diameter of less than 10 microns, is mainly used as electronic yarns and industrial yarns. The electronic yarn is mainly used for textile electronic cloth, and the downstream is printed circuit board for electronic components. The common monofilament diameter is 5, 7, and 9 micrometers; industrial yarn is used for industrial fabrics, such as fire curtain, mold construction, timing belt, cord, and sleeve. Tubes, etc., common filaments are 5-9 microns in diameter.


Roving, usually referred to as a yarn having a filament diameter of 10 microns or more, is a twist-free yarn. The rovings are divided into direct yarns and plied yarns. The direct yarn refers to a bundle in which parallel monofilaments are not twisted and combined, and the plied yarn refers to a bundle in which parallel strands (multiple strands of roving) are not twisted and combined. The ply yarn is actually a process of winding the yarn to synthesize a low-tex raw yarn into a high-tex product. Tex is the linear density of the yarn, as in the usual 2400 tex, which means that the weight of the 1000 m yarn is 2400 g.


The fiberglass yarn is divided into crepe and crepe according to whether it is twisted or not. The twist is the number of revolutions between the fiber and the fiber per unit length, in units of 捻/m, divided into S捻 and Z捻 according to their different steering. The role of twisting is mainly to improve the cohesion between the fibers and improve the stress of the single fibers. However, since it is inconvenient to impregnate the resin after twisting, the fibers used in the general FRP are all non-twisted yarns, such as pultruded yarns and wound yarns. Twisted yarn is mainly used in some textile products, such as electronic cloth.





2. From fiberglass yarn to fiberglass products, the process is complex and diverse


(1) Classification of glass fiber products


Glass fiber yarns are usually used in the downstream field in the form of glass fiber products, including non-woven products and textile products.





Glass fiber products are mainly divided into non-woven products and textile products. Nonwoven articles refer to products made of glass fibers by a non-woven method (mechanical, chemical or thermal), mainly including glass fiber mats (such as chopped strand mat, continuous felt, needle felt, etc.), and ground fibers.




(2) From glass fiber yarn to fiberglass products, the process is complex and diverse


Common such as hand lay-up process, pultrusion process, felting process, BMC molding process, CFRT molding process, GMT molding process, etc.




3. FRP is the most common fiberglass product


Glass-Fiber Reinforced Plastics is a composite material based on glass fiber and its products (felt, cloth, tape, etc.) as a reinforcing material and synthetic resin as matrix. Because the strength of glass fiber reinforced plastic is equivalent to steel, it also contains glass fiber and has the color, shape and corrosion resistance, electrical insulation and heat insulation of glass. Therefore, it is commonly known as “glass reinforced plastic in China”. FRP is the largest market for glass fiber. The amount of glass fiber accounts for 70-75% of the total amount of glass fiber products, followed by glass fiber textile products account for about 25-30%, and a small amount of glass fiber reinforced materials for reinforcing asphalt.


FRP is divided into glass fiber reinforced thermoplastic (FRTP) and glass fiber reinforced thermoplastic (FRP) according to the type of resin. The heating and softening process of thermoplastic (LFT, etc.) is physical change, reversible, and can be repeated. get on. The thermosetting plastic (SMC, etc.) undergoes a chemical change in the heat curing process, and the inside of the molecular chain is hinged to stabilize the shape, and heating after hardening destroys the internal structure, so that it cannot be processed again by heating.






FRP is divided into wound products, molded products (SMC/BMC), extruded products, hand lay-up products, liquid molded products, thermoplastic composite products (SFT, LFT, GMT, CFT) according to different processes. Most of the wind power blades are liquid molded products, which were previously made of thermosetting glass reinforced plastic. Under the trend of large-scale and lightweight development of blades, thermoplastic glass reinforced plastics have also appeared. Most of the lightweight materials for automobiles are LFT, GMT and SMC/BMC products, which are used in parts, interiors, front end brackets, engine underguards and other fields.


02 downstream demand analysis


1. Glass fiber downstream demand is strong


The downstream applications of glass fiber are diverse, mainly including the following fields: building materials, transportation, industry, wind power and other industries. Corresponding to its diverse application environments, there are many varieties of glass fiber. At present, there are more than 5,000 varieties of fiberglass in the world. Specifications exceed 60,000.




In the global glass fiber consumer market, the main application areas of glass fiber are concentrated in the fields of construction, transportation, industry, electrical and electronic, new energy, etc., accounting for 32%, 28%, 21%, 11% and 8% respectively;


In China's glass fiber consumer market, the main application areas of glass fiber are concentrated in the construction and transportation sectors, accounting for 60% of the total. According to Owens Corning, the global leader in glass fiber products, the demand growth rate of the glass fiber industry is about 1.6 times that of the global industrial output value. According to the growth rate of global industrial output value of 3% (about 6% in China) in the next three years, The demand for glass fiber industry is about 5% (China is close to 10%).


In 2017, with the recovery of wind power and the heating up of infrastructure, we judge that domestic demand for glass fiber is expected to pick up. It is assumed that demand growth in wind power sector will rebound to 15%, demand growth in construction industry will rebound to 4%, demand in transportation sector will be roughly flat, and growth in other industries will increase. At the same rate, the annual growth rate of glass fiber demand is expected to rebound to 5%.


2. Measurement of automotive lightweight demand


Glass fiber composite is the material of choice for lightweight vehicles


The Ministry of Industry and Information Technology issued the "Limited Fuel Consumption Limits for Passenger Cars". The standard further tightens the fuel consumption limit of passenger vehicles, increases the minimum market access requirements for passenger vehicles, and ensures the realization of the energy consumption target of 5L/100km in 2020. The fourth phase standard has been introduced since 2016, 2016. The average fuel consumption of the whole industry is 6.56L/100km, and the implementation pressure is relatively high. Penalties are imposed by non-standard enterprises. Under the stringent energy consumption standards, car lightweighting will become the core means for major manufacturers to complete standards. If the vehicle's overall weight is reduced by 8%-10%, the fuel efficiency can be increased by 6%-8%; for every 100 kilograms of the vehicle's overall vehicle quality, the fuel consumption per 100 kilometers can be reduced by 0.3-0.6 liters. Therefore, the light weight of automobiles is a relatively direct means for major auto companies to reach the limit of fuel consumption of 100 kilometers. At present, technologies such as carbon fiber, aluminum alloy, magnesium alloy, glass fiber composite material and carbon fiber composite material are commonly used in the industry for technological improvement and upgrading.