Glass fiber material classification

According to the shape and length, glass fiber can be divided into continuous fiber, fixed length fiber and glass wool. According to the glass component, it can be divided into alkali-free, chemical-resistant, high-alkali, medium-alkali, high-strength, high-elasticity modulus and alkali-resistant glass. Fiber, etc.

The main raw materials for the production of glass fiber are: quartz sand, alumina and pyrophyllite, limestone, dolomite, boric acid, soda ash, thenardite, fluorite and ground glass fiber. The production methods are roughly divided into two categories: one is to directly form the molten glass into fibers; the other is to first make the molten glass into a glass ball or rod with a diameter of 20 mm, and then remelt it in various ways to make a diameter of 3 ~ Very fine fiber of 80 μm.

An infinitely long fiber drawn by a mechanical drawing method by a platinum alloy plate is called a continuous glass fiber and is generally called a long fiber. Non-continuous fibers made by rolls or air streams, called fixed length glass fibers, are commonly referred to as short fibers. Fine, short, floc-like fibers made by centrifugal force or high-speed airflow are called glass wool. Glass fiber can be processed into various forms of products, such as yarn, roving, chopped strand, cloth, belt, felt, board, tube and so on.

Glass fiber is divided into different grades according to composition, nature and use. According to the standard level (see table), E-class glass fiber is the most common and widely used in electrical insulation materials; S-class is special fiber, although the output is small, but it is very important, because it has super strength, mainly used for military defense, such as Bulletproof box, etc.; Class C is more chemical resistant than Class E, used for battery separators and chemical filters; Class A is alkaline glass fiber for the production of reinforcing materials.

The glass used to produce glass fiber is different from the glass of other glass products. The glass components used in commercially available fibers are as follows:

E-glass

Also known as alkali-free glass, it is a borosilicate glass. At present, it is the most widely used glass component for glass fiber. It has good electrical insulation and mechanical properties. It is widely used in the production of glass fiber for electrical insulation. It is also widely used in the production of fiberglass for glass reinforced plastic. Its disadvantage is that it is easy to be Inorganic acid is eroded and therefore not suitable for use in an acidic environment.

C-glass

Also known as medium alkali glass, it is characterized by chemical resistance, especially acid resistance is better than alkali-free glass, but the electrical properties are poor, the mechanical strength is lower than that of alkali-free glass fiber by 10% to 20%, usually the foreign medium-alkali glass fiber contains certain The amount of boron trioxide, while China's medium alkali glass fiber is completely free of boron. In foreign countries, medium-alkali glass fiber is only used to produce corrosion-resistant glass fiber products, such as glass fiber surface felts.

Glass fiber rods are also used to reinforce asphalt roofing materials, but in China, alkali glass fiber occupies more than half (60%) of glass fiber production. It is widely used in the reinforcement of FRP and the production of filter fabrics, dressing fabrics, etc. because of its low price. It has strong competitiveness in alkali-free glass fiber.

High-strength glass fiber

It is characterized by high strength and high modulus. Its single fiber tensile strength is 2800 MPa, which is about 25% higher than that of alkali-free glass fiber. The elastic modulus is 8600 MPa, which is higher than that of E-glass fiber. The FRP products produced by them are mostly used in military, space, bulletproof armor and sports equipment. However, due to the high price, it is still not popularized in civilian use, and the world's output is about several thousand tons.

AR fiberglass

Also known as alkali-resistant glass fiber, mainly developed to enhance cement.

A glass

Also known as high alkali glass, it is a typical sodium silicate glass, which is rarely used for the production of glass fiber due to poor water resistance.

E-CR glass

It is an improved boron-free alkali-free glass for the production of glass fiber with good acid and water resistance. Its water resistance is 7-8 times better than that of alkali-free glass fiber. The acid resistance is also superior to that of alkali glass fiber. New varieties developed for underground pipelines, storage tanks, etc.

D glass

Also known as low dielectric glass for the production of low dielectric glass fibers with good dielectric strength.

In addition to the above glass fiber components, a new alkali-free glass fiber has appeared in recent years, which is completely free of boron, thereby reducing environmental pollution, but its electrical insulation properties and mechanical properties are similar to those of conventional E glass. There is also a double-glass glass fiber that has been used in the production of glass wool and is said to have potential for use as a FRP reinforcement. In addition, there is fluorine-free glass fiber, which is an improved alkali-free glass fiber developed for environmental protection.

Identification of high alkali glass fiber

The simple method of inspection is to put the fiber in boiling water and cook for 6-7 hours. If it is a high-alkali glass-nitrocellulose fiber, after boiling water, the fibers in the warp and weft directions are all loosened.