1. The pet plastic cup has good physical properties

PET plastic cups have good physical properties, the impact strength is 3 to 5 times that of other plastic films, and the folding resistance is strong.

Oil resistance, fat resistance, dilute acid, dilute alkali, and most organic solvents. It has good high and low temperature safety performance, can be used for a long time in the temperature range of 120 °C, can withstand high temperature of 150 °C in a short term, and can withstand ultra-low temperature of -70 °C, and has little effect on its physical properties at high and low temperatures. Low gas and water vapor permeability, and good gas, water, oil and odor barrier properties. High transparency, can block ultraviolet light, and good gloss. Non-toxic, odorless, good hygiene and safety factor, can be directly used for food packaging.

The molecular structure of PET plastic is highly symmetrical and has certain crystal orientation ability, so it has high film-forming and forming properties. PET plastic has good optical properties and weather resistance, and amorphous PET plastic has excellent optical transparency. Another PET plastic has excellent wear and tear friction and dimensional stability and electrical insulation. Bottles made of PET have high strength, good transparency, non-toxicity, anti-penetration, light product quality, and high productivity, so they are widely used. The molecular chain structure of PBT and PET is similar, and most of the properties are the same, except that the main chain of the molecular structure has changed from two methylene groups to four, so the molecule is more flexible and the processing performance is better.

2. Why does the pet plastic cup change color?

PET plastic cup manufacturers believe that the root cause of discoloration is also various, mainly including:

1. Equipment

(1) The equipment is not clean. Dust or other soot deposits on the silo contaminate the raw material and discolor it.

(2) The thermocouple, the temperature controller or the heating system is out of balance, causing the temperature control to fail.

(3) There are obstacles in the barrel, which can easily cause the plastic to degrade; there are metal foreign objects stuck in the barrel or screw groove, and the plastic is discolored by continuous grinding.

2. Mould

(1) The mold is poorly vented, the plastic is compressed adiabatically, reacts violently with oxygen under high temperature and high pressure, and burns the plastic.

(2) The mold gate is too small.

(3) There are too many lubricants and release agents in the material or in the mold. If necessary, the barrel should be cleaned regularly to remove additives such as antistatic properties that are worse than plastics in terms of heat resistance.

(4) The size of nozzle hole, main channel and branch channel is too small.

3. Process

(1) The screw speed is too high and the pre-plastic back pressure is too large.

(2) The temperature of the barrel and nozzle is too high.

(3) The injection pressure is too high, the time is too long, and the injection speed is too fast to make the product discolored.

4. In terms of raw materials

(1) The material is contaminated.

(2) High moisture and volatile content.

(3) Decomposition of colorants and additives.