PBT Product Introduction

2.5 Dimensional Stability With low water absorption (usually less than 0.1%), PBT has excellent dimensional stability. Whether dry or humid, PBT - based products have minimal size changes, which is crucial for precision - molded parts in electronics and precision machinery. 3. Production Process PBT production mainly has two steps: esterification and polycondensation. 3.1 Esterification Terephthalic acid or its dimethyl ester reacts with 1,4 - butanediol with a catalyst. Using terephthalic acid produces water; using dimethyl terephthalate produces methanol. This reaction occurs at 180 - 250°C and certain pressure to form low - molecular - weight prepolymers. 3.2 Polycondensation The prepolymers from esterification are further polymerized at 230 - 270°C under high - vacuum. The reaction increases the molecular weight until the desired PBT product is achieved. Removing small - molecule by - products like water or methanol is key to product quality. 4. Application Fields 4.1 Electronics and Electrical Appliances PBT is widely used in this industry. For example, it makes connectors due to high - temperature resistance and good electrical insulation. PBT insulators prevent electrical leakage, and switch housings made of it ensure long - term operation. It's also used in coil bobbins, benefiting from high - temperature resistance and low water absorption. 4.2 Automotive Industry In cars, PBT is used for engine covers, radiator grilles, and interior trim. Its heat resistance and mechanical strength suit engine - related parts, while good surface finish, dimensional stability, and easy molding make it great for interior components. 4.3 Textile Industry PBT fibers are used in textiles. They have good elasticity, softness, and wrinkle - resistance. Blended with other fibers like cotton and polyester, they make high - performance fabrics, especially popular in sportswear for breathability and comfort.