POM GM-20宝理

POM GM-20宝理--GM-20 is a polyformaldehyde (POM) copolymer product containing 20% glass fiber reinforced filler.

因为干燥处理可提高制品的表面光泽度，减少模垢、气痕等不良现象出现。而对开封并放置一定时间的POM料，会有一定的吸湿，所以必须经干燥后再用于成型，否则会在注射成型中产生较多的模垢，或者因产生银纹而使制品的外观不良。对POM进行注射成型时，为了达到较好的制品外观和减少成型时的模垢，要求其原料的含水率不超过0.1%。较高的干燥温度虽能使树脂烘干所需的时间大为缩短，但因过高的温度易使POM制品表面氧化变黄，所以采用较温和的干燥条件。均聚POM可采用的干燥温度为80~90℃，干燥时间为2~4h。共聚POM可采用干燥温度为90~100℃，干燥时间为2~4h。在干燥上的区别是因为共聚甲醛的吸湿率低于均聚甲醛，且热稳定性要好，所以采用高温烘烤。

When POM plastic material is processed, the temperature of barrel is too high, the thermal stability of POM is poor, the temperature is too high or the time is too long, all of which will cause decomposition, resulting in the decline of product performance, especially when the temperature exceeds 250 C, the decomposition speed will be accelerated, and the formaldehyde gas which strongly stimulates the eyes will spill over. In serious cases, the product will produce bubbles or discoloration. Moreover, because POM is a shear-sensitive polymer, the melt fluidity above melting point is not obvious to temperature change, but sensitive to shear rate. Therefore, the effect of improving the fluidity of POM only by increasing the temperature of POM is limited. When forming thin-walled products, it is generally recommended to use POM grade with higher melt flow rate. The melting temperature of homopolymer POM is 175 C. The temperature of resin can be set between 190 and 200 C, because the melting temperature of homopolymer POM should be taken into account to set a higher temperature and to prevent its thermal decomposition as much as possible. The melting temperature of copolymer POM is 165 C. Because the processing window is relatively wide, the resin temperature can be set at 180 ~ 200 C in injection moulding.


Resin Description: Whether homopolymer POM or copolymer POM, when moulding thin-walled or multi-cavity moulding products, faster injection speed should be adopted. This is because the injection moulding of such parts requires the system to have good fluidity. As mentioned earlier, POM melt belongs to shear-sensitive polymer. To increase its flowability, it can be achieved by increasing injection speed. At the same time, in the above applications, the cooling rate of POM crystallization will be very fast, and surface defects such as wrinkles, speckles and weld marks will easily occur on the products. Therefore, it is necessary to improve the injection speed