The preparation method of reinforced modified PBT copolyester

Abstract

The invention relates to a preparation method of enhanced modified PBT copolyester, which is a copolyester that can be used in the field of film and engineering plastics. Formic acid, inorganic crystallization nucleating agent, terephthalic acid or dimethyl terephthalate, and 1,4-butanediol are liquid-phase polymerized to obtain reinforced modified PBT polyester in one step. This method improves the mechanical properties and heat resistance of PBT, and can avoid the disadvantages of glass fiber blended modified PBT polyester, such as poor toughness, strong hygroscopicity, poor fluidity, high injection temperature and pressure, and serious equipment wear and tear.

Description

technical field [0001] The invention belongs to the field of polymer compounds, and in particular relates to a preparation method of PBT copolyester. Background technique [0002] Polybutylene terephthalate, referred to as PBT, is an engineering plastic with excellent comprehensive properties. PBT can be rapidly molded at a relatively low temperature. Its products have good electrical properties, temperature resistance, mechanical strength, surface It has high hardness and good dimensional stability, so it is widely used in the fields of electronic appliances, automobiles and machinery. [0003] The main products of modified PBT polyester are flame retardant, glass fiber reinforced, flame retardant glass fiber reinforced, blended alloy grade, etc. The market demand for flame retardant glass fiber reinforced PBT accounts for more than 70% of modified PBT. It has the widest range of applications, so it has become the focus of research at home and abroad for flame-retardant gl...

AI Technical Summary

Problems solved by technology

[0004] The use of glass fiber reinforced or inorganic filled modified PBT polyester can more than double the tensile strength and bending strength, and the heat distortion temperature is also greatly increased. It can work for a long time at 140 ° C, but the glass fiber reinforced PBT composite The product toughness of the material decreases, while the brittleness increases, and the moisture absorption performance is greatly enhanced

During processing, the melt viscosity increases and the fluidity becomes poor. The injection pressure is much higher than that without glass fiber, and the injection temperature is 10°C-30°C higher than that without glass fiber. The injection pressure is high, and glass fiber can enter the plastic product. The surface of the product makes the surface of the product very rough and cannot achieve the appearance quality of pure plastic

Moreover, after the glass fiber is reinforced, the glass fiber is a material with high hardness. After the additive volatilizes at high temperature, it will produce a very corrosive gas, which will cause great wear and corrosion to the screw of the injection molding machine and the injection mold.