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Glass fiber reinforced unsaturated polyester block molded plastic
Writer:admin    Released:2018-05-31 14:47:52    Type:【L】【M】【S

Glass fiber reinforced unsaturated polyester block mould plastic can be widely used in low voltage electrical appliances and automobile industry, it is a new type of thermosetting material.This paper introduces the synthesis formula, performance index and development of zero-shrinkage block mould plastics for automobile headlight.

General situation of

Glass fiber reinforced unsaturated polyester block molded plastic is a new thermosetting material developed in the early 1970s.The United States calls it block mold plastic (BMC), the United Kingdom and Europe called it the bulk mold plastic (DMC), Japan called premix (PMC).BMC is a highly reactive unsaturated polyester resin or its modified resin as matrix, low shrinkage resin, add chopped glass fiber, inorganic filler and change hair agent, release agent, pigment and so on of premixed clumps molding compound.This kind of mould plastic has good processing performance, its product strength is high, dimension is stable, resist arc, resist electric leakage, resist heat and resist chemical etch.BMC can be formed by compression molding, transfer molding and injection molding. It is a new thermosetting material for phenolic plastics and melamine plastics.When BMC was launched, its main application area was low-voltage electrical appliances. In 1973, the total production of BMC in the world was 36,200 thousand tons, of which the consumption of electric appliances was as high as 26,200 tons, accounting for 73%.With the improvement of BMC manufacturing technology and the introduction of high-quality BMC products into the automotive industry, the planned consumption of the us model 1979 SMC/BMC reached 130,000 tons in 1990.

China's BMC production technology really began in the early 1980s.At that time, in order to make domestic electrical automatic air switch in a short period of time to catch up with the international level, the Shanghai huatong company (hereafter called sacsc) introduced from Westinghouse (USA) 100 ~ 3000 a whole series of 53 models of molded case switches manufacturing technology introduced from Japan, zhejiang jiaxing electronic factory terasaki company Marine circuit breaker manufacturing technology, etc., in order to solve our country electric based without a long low-pressure electric equipment form a complete set of problem such as transmission and distribution.The plastic shell of the products produced by the above introduction technology shall be made of BMC materials, otherwise the products cannot enter the international market.Therefore, in 1983, the Shanghai municipal economic commission organized 5 units to jointly tackle the problem and developed the BMC, which was finally successful.Built in 1986, the Shanghai institute of synthetic resin 500 tons/year BMC production workshop, Shanghai shuguang chemical plant also successively built production facility of BMC, immediately the country with dozens of electric equipment production unit adopts the domestic BMC production of low voltage circuit breaker shell, Marine molded case automatic switch, centrifugal switch and other insulation parts.In 1987, Harbin insulation material factory and other three units jointly introduced the British BMC production technology.Up to now, there are more than 40 or 50 BMC production plants in China, most of which are used in the electric field.There are few applications in the car industry.This paper mainly introduces the application of BMC in automobile industry, especially the application of BMC in automobile headlight reflector.

BMC in the unsaturated poly phenolic resin is adopted by the dibasic alcohol and saturated dibasic acid, unsaturated dibasic acid condensation, condensation is completed, the dissolved in crosslinking monomer styrene, styrene with unsaturated polyester crosslinked, form a thermosetting shape mesh structure, bring high strength to BMC.BMC is composed of medium - and low-shrinkage resins, usually thermoplastic resins incompatible with unsaturated polyester resins, which can reduce the shrinkage rate of BMC.Selecting thermoplastic or modified rubber with high bulk expansion coefficient can reduce the shrinkage rate of BMC to zero (i.e., the shrinkage rate < 0.05).The composition of BMC contains about 50% inorganic fillers, which can reduce the cost of BMC and the shrinkage rate of BMC.The short cut glass fiber is evenly dispersed in the BMC material, which has good binding force with unsaturated polyester resin, making BMC have higher mechanical strength.

The properties of BMC are affected not only by its composition, proportion and preparation process, but also by the type and production process of unsaturated polyvinylidene resin.For example, the unsaturated polyvinylic acid resin produced by phthalic acid has better mechanical strength, heat resistance and chemical corrosion resistance than the resin produced by phthalic acid.If vinyl resin is used, the effect is better.

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