Wuhan Handern PET Sheet
DATE：2020/9/28 8:35:02 / READ： / SOURCE：This station
Wuhan Handern PET Sheet
1. Selection of raw materials and their performance
The raw material of PET sheet is mainly random polyethylene terephthalate (APET). www.handern.com Non-woven equipment
(1) Intrinsic viscosity. The performance of APET is related to relative molecular mass, and relative molecular mass is determined by intrinsic viscosity. The intrinsic viscosity is low, the physical properties of the sheet are poor, and the impact strength is low; the intrinsic viscosity is high, the physical properties of the sheet are improved, and the impact strength is large, but the fluidity is poor, the extrusion load is large, and the molding is difficult. Therefore, it is better to produce APET sheets with polyester resins with an intrinsic viscosity of 0.76-0.85.
(2) Melting point. The melting point of PET homopolymer is 263°C-265°C, and the melting point of PET copolymer varies greatly due to the different content of auxiliary materials and auxiliary materials copolymerized by various raw material manufacturers. Commonly used copolymerization materials include isophthalic acid (1A), cyclohexanedimethanol (CHDM), diethylene glycol (DEG), etc. Generally, copolycondensation polyester resin with a melting point of 242℃-250℃ is used, so that its melting point is low and convenient Extrusion processing, high crystallization temperature, slow crystallization speed, convenient for secondary molding of APET sheet. www.handern.com Non-woven equipment
(3) Acetaldehyde content. Thermal decomposition of polyester will produce acetaldehyde, and acetaldehyde is odorous and toxic, so its content is required to be less than 2 parts per million.
(4) Moisture content. The moisture content of APET resin directly affects its drying effect, and its moisture content is required to be less than 0.3%. www.handern.com Non-woven equipment
(5) Yellow index. APT sheet is often used as a visual packaging material, and its yellow index L is greater than or equal to 85, b≤0.5 www.handern.com non-woven equipment
(6) End carboxyl group content, the content of COOH can be used as an indicator to measure the thermal stability of PET. Generally, the end carboxyl content is required to be less than 0.03mol/kg; in addition, its thermal stability and crystallization performance should also be considered. Easy to heat aging makes the intrinsic viscosity decrease and the color turns yellow; the slower the crystallization speed of the polyester resin used for extruding APET sheet, the better. www.handern.com Non-woven equipment
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