PET plastic cup color causes

Update:23 Feb 2018

       The causes of discoloration are also many, mainl […]

       The causes of discoloration are also many, mainly:
1 Device
(1) The equipment is not clean. Dust or other dust deposited on the hopper makes the material contaminated and discolored.
(2) thermocouple, temperature controller or heating system disorders caused by temperature control failure.
(3) there are obstacles in the barrel, easy to promote plastic degradation; barrel or screw slot with metal foreign objects, the constant grinding to plastic discoloration.
2 Molds
(1) poor mold exhaust, plastic is adiabatic compression, high temperature and high pressure with violent reaction of oxygen, burn plastic.
(2) mold gate is too small.
(3) material or in-mold lubricant, release agent too much. When necessary, the cylinder should be cleaned periodically to remove additives such as antistatic properties that are worse than the heat resistance of plastic.
(4) Nozzle hole, the main flow channel and the size of the shunt is too small.
3  Aspects of technology
(1) screw speed is too high, plastic back pressure is too large.
(2) barrel, nozzle temperature is too high.
(3) injection pressure is too high, the time is too long, the injection speed is too fast to make the product discolored.
4  Aspects of raw materials
(1) material is contaminated.
(2) high moisture and volatile content.
(3) colorants, additives decomposition.