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Fiberglass is an excellent performance of inorganic non-metallic materials, a wide variety of advantages are good insulation, heat resistance, corrosion resistance, high mechanical strength, but the disadvantage is brittle, wear resistance is poor. It is a glass ball or waste glass as raw materials by high-temperature melting, drawing, winding, weaving and other processes into its monofilament diameter of a few microns to more than 20 microns, equivalent to a hair 1/20-1/5, each bundle of fibers by hundreds or even thousands of monofilaments composed of raw silk. Fiberglass is usually used as reinforcing materials in composite materials, electrical insulation materials and thermal insulation materials, circuit boards and other areas of the national economy.
1, Physical properties of fiberglass
Melting point 680 ℃
Boiling point 1000 ℃
Density 2.4-2.7g/cm³

2, Chemical composition
The main components are silica, alumina, calcium oxide, boron oxide, magnesium oxide, sodium oxide, etc., according to the amount of alkali content in the glass can be divided into non-alkali glass fibers (sodium oxide 0% to 2%, is an aluminum borosilicate glass), medium alkali fiberglass (sodium oxide 8% to 12%, is a boron-containing or boron-free soda-lime silicate glass) and high alkali fiberglass (sodium oxide 13% or more, is a soda-lime silicate glass). ).

3, raw materials and their applications
Fiberglass than organic fibers, high temperature, non-combustible, anti-corrosion, thermal and acoustic insulation, high tensile strength, good electrical insulation. But brittle, poor abrasion resistance. Used in the manufacture of reinforced plastics or reinforced rubber, as a reinforcing material fiberglass has the following characteristics, these characteristics make the use of fiberglass is far more than other types of fibers to a wide range of development speed is also far ahead of its characteristics are listed below:
(1) High tensile strength, small elongation (3%).
(2) High coefficient of elasticity, good rigidity.
(3) Elongation within the limits of elasticity and high tensile strength, so absorb impact energy.
(4) Inorganic fiber, non-combustible, good chemical resistance.
(5) Small water absorption.
(6) Good scale stability and heat resistance.
(7) Good processability, can be made into strands, bundles, felts, fabrics and other different forms of products.
(8) Transparent products can transmit light.
(9) The development of surface treatment agent with good adhesion to resin is completed.
(10) Inexpensive.
(11) It is not easy to burn and can be fused into glassy beads at high temperature.
Fiberglass according to the form and length, can be divided into continuous fiber, fixed-length fiber and glass wool; according to the glass composition, can be divided into non-alkali, chemical-resistant, high alkali, alkali, high-strength, high modulus of elasticity and alkali-resistant (anti-alkali) fiberglass and so on.

4, the main raw materials for the production of fiberglass
At present, the main raw materials for the domestic production of fiberglass is quartz sand, alumina and chlorite, limestone, dolomite, boric acid, soda ash, manganese, fluorite and so on.

5, production methods
Roughly divided into two categories: one is made of molten glass directly into fibers;
A class of molten glass is first made of glass balls or rods with a diameter of 20mm, and then remelted in a variety of ways to heat made of very fine fibers with a diameter of 3 ~ 80μm.
Through the platinum alloy plate to mechanical drawing method to pull the infinite length of the fiber, known as continuous glass fiber, commonly known as long fiber.
Through the roller or airflow made of discontinuous fibers, known as fixed-length fiberglass, commonly known as short fibers.

6, fiberglass classification
Fiberglass according to the composition, nature and use, divided into different levels.
According to the standard level of provisions, E-class glass fiber is the most common use, widely used in electrical insulation materials;
S-class for special fibers.
Production of fiberglass with glass is different from other glass products.
Internationally commercialized fiberglass composition is as follows:

(1) E-glass
Also known as alkali-free glass, is a borosilicate glass. Currently is one of the most widely used glass fiber glass composition, with good electrical insulation and mechanical properties, widely used in the production of electrical insulation with glass fiber, also used in large quantities for the production of fiberglass for fiberglass reinforced plastic, its disadvantage is easy to be eroded by inorganic acids, so it is not suitable for use in acidic environments.

(2) C-glass
Also known as medium alkali glass, which is characterized by chemical resistance, especially acid resistance is better than alkali glass, but the electrical properties of poor mechanical strength is lower than alkali glass fibers 10% to 20%, usually foreign medium alkali glass fibers contain a certain amount of boron dioxide, and China’s medium alkali glass fibers are completely boron free. In foreign countries, medium alkali fiberglass is only used for the production of corrosion-resistant fiberglass products, such as for the production of glass fiber surface mat, etc., also used to enhance the asphalt roofing materials, but in our country, medium alkali fiberglass occupies a large part of glass fiber production (60%), widely used in fiberglass reinforced plastic enhancement as well as filtration fabrics, wrapping fabrics, etc., because of its price is lower than the price of non-alkaline glass fiber and have a stronger competitive edge.

(3) High strength fiberglass
Characterized by high strength and high modulus, it has a single fiber tensile strength of 2800MPa, which is about 25% higher than the tensile strength of alkali-free fiberglass, and a modulus of elasticity of 86,000MPa, which is higher than that of E-glass fiber. The FRP products produced with them are mostly used in military, space, bulletproof armor and sports equipment. However, due to the expensive price, now in the civilian aspects can not be promoted, the world production is only a few thousand tons or so.

(4) AR fiberglass
Also known as alkali-resistant fiberglass, alkali-resistant fiberglass is fiberglass reinforced (cement) concrete (referred to as GRC) rib material, is 100% inorganic fibers, in the non-load-bearing cement components is an ideal substitute for steel and asbestos. Alkali-resistant fiberglass is characterized by good alkali resistance, can effectively resist the erosion of high alkali substances in cement, strong grip, modulus of elasticity, impact resistance, tensile and flexural strength is very high, non-combustible, frost resistance, resistance to temperature and humidity changes, crack resistance, seepage resistance is excellent, with a strong design, easy to form, etc., alkali-resistant fiberglass is a new type of reinforcing material that is widely used in high-performance reinforced (cement) concrete. Green reinforcing material.

(5）A Glass
Also known as high alkali glass, is a typical sodium silicate glass, due to poor water resistance, rarely used in the production of fiberglass.

(6）E-CR glass
E-CR glass is a kind of improved boron-free alkali-free glass, which is used for the production of fiberglass with good acid and water resistance. Its water resistance is 7-8 times better than that of alkali-free fiberglass, and its acid resistance is also much better than that of medium-alkali fiberglass, and it is a new variety developed for underground pipes and storage tanks.

(7) D Glass
Also known as low dielectric glass, it is used to produce low dielectric fiberglass with good dielectric strength.
In addition to the above fiberglass components, there is now a new alkali-free fiberglass, it is completely boron free, thereby reducing environmental pollution, but its electrical insulation properties and mechanical properties are similar to the traditional E glass.
There is also a double glass composition of fiberglass, has been used in the production of glass wool, in the fiberglass reinforced plastic reinforcing material also has the potential. In addition there are fluorine-free glass fibers, is developed for environmental requirements and improved alkali-free fiberglass.

7. identification of high alkali fiberglass
The test is a simple way to put the fiber in boiling water and cook 6-7h, if it is a high alkali fiberglass, after boiling water after cooking, warp and weft of the fiber all become loose.

8. There are two kinds of fiberglass production process
a) Twice molding – crucible drawing method;
b) One time molding – pool kiln drawing method.
Crucible drawing method process, the first high-temperature melting of glass raw materials made of glass balls, and then the second melting of glass balls, high-speed drawing made of fiberglass filaments. This process has high energy consumption, molding process is not stable, low labor productivity and other disadvantages, basically eliminated by large glass fiber manufacturers.

9. Typical Fiberglass Process
Pool kiln drawing method of chlorite and other raw materials in the kiln melted into a glass solution, excluding air bubbles through the pathway transported to the porous leakage plate, high-speed drawing into the fiberglass filament. The kiln can be connected to hundreds of panels through multiple pathways for simultaneous production. This process is simple, energy-saving, stable molding, high efficiency and high yield, to facilitate large-scale fully automated production, and has become the mainstream of the international production process, with the process of production of fiberglass accounted for more than 90% of global production.