Selection and use of PET plastic cup
Pet plastic cup has good physical properties
PET plastic cup has good physical properties. Its impact strength is 3~5 times that of other plastic films. It has strong folding resistance.
Resistant to oil, fat, dilute acid, dilute alkali, most organic solvents. It can be used for a long time within the temperature range of 120℃. It can be used for a short period of time. It can withstand high temperature of 150℃ and ultra-low temperature of -70℃. Gas and water vapor permeability is low, has good gas, water, oil and odor performance. High transparency, can block ultraviolet light, good shine. No toxicity, no smell, good hygiene and safety, can be used directly for food packaging.
The molecular structure of PET plastic is highly symmetrical and has the ability of crystal orientation, so it has high film-forming property and property. PET plastic has good optical properties and weather resistance, and amorphous PET plastic has excellent optical transparency. The other PET plastic has excellent wear-resistance, wear and tear, frictional properties, dimensional stability and electrical insulation. PET bottles have been widely used because of their high strength, transparency, non-toxicity, anti-infiltration, light product quality and high productivity. The structure of PBT is similar to that of PET molecular chain, and most of the properties are the same, except that the main chain of molecular structure changes from two methylene groups to four, so the molecules are more pliable and have better processing performance.
2. Why do pet plastic cups change color
PET plastic cup manufacturers believe that the root cause of discoloration is also in various aspects, mainly including:
(1) the equipment is not clean. Dust or other soot deposits on the bin and discolors the raw material.
(2) maladjustment of thermocouple, temperature controller or heating system leads to the failure of temperature control.
(3) there are obstacles in the machine barrel, easy to promote plastic degradation; There is a metal foreign body stuck in the barrel or screw slot, and the continuous grinding discolors the plastic.
(1) the mold exhaust is poor, the plastic is adiabatic compression, under high temperature and high pressure with oxygen violent reaction, burn the plastic.
(2) the mold gate is too small.
(3) too much lubricant and stripper in the material or in the mold. When necessary, the cylinder should be cleaned regularly to remove the anti-static additives worse than the heat resistance of the plastic.
(4) the size of nozzle hole, main channel and shunt is too small.
Three aspects of technology
(1) the screw speed is too high and the premolding back pressure is too high.
(2) the temperature of barrel and nozzle is too high.
(3) the injection pressure is too high, the injection time is too long, the injection speed is too fast and the product discoloration.
Iv. Raw materials
(1) the material is contaminated.
(2) high moisture and volatile content.
(3) decomposition of colorant and additive.
Detailed description of the code of pet plastic cup
"01" -- PET(polyethylene terephthalate)
Mineral water bottles, carbonated drink bottles are all made of this kind of material. It has the characteristics of high penetration, good toughness and good hardness. Compared with PP cup, PET plastic cup is more transparent, with good hardness and PS cup, with good toughness and not easy to break. This kind of material temperature resistance to 70℃, suitable for warm drinks or frozen drinks.
"02" -- HDPE(high-density polyethylene)
Plastic containers for cleaning supplies, bath goods, and plastic packaging bags currently used in department stores and department stores are mostly made of such materials, which can withstand the high temperature of 110℃. Plastic packaging bags used for food marking can be used to hold food.
"03" -- PVC(polyvinyl chloride)
According to introducing, the plastic product of this kind of material is easy the poisonous harmful thing that forms comes from two respects, it is the monomolecular vinyl chloride that did not have by thorough polymerization in production technological process flow, 2 it is the harmful material in plasticizer. These two kinds of chemicals are easy to separate out when they meet high temperature and grease. After the poisonous substance enters the body with the food materials, it is very easy to cause cancer. At this stage, such utensils have long been less used for packaging food. If in use, don't let it get hot.
"04" -- LDPE(low density polyethylene)
Plastic wrap bags, plastic film and so on are all made of this kind of material. Temperature resistance is not high, usually, the qualified PE plastic bag in the temperature exceeds 110℃ will appear hot solution phenomenon, will leave some of the body can not decompose the plastic preparation.
"05" -- PP(polypropylene)
Microwave meal box is made of this kind of material and can withstand 130℃. It is the only plastic box that can be put into the microwave oven and can be reused after careful cleaning.
"06" -- PS(polystyrene)
It is used to make bowls of instant noodles and foamed fast food boxes. High temperature and cold resistance, but do not put in the microwave oven, in case the temperature is too high and release chemicals.
"07" -- PC and other categories
PCS, A material widely used, especially in baby bottles and space cups, are controversial because they contain bpa. In theory, experts say, as long as bisphenol A is 100 percent converted into plastic during the PC manufacturing process, it means the product is free of bisphenol A, let alone released. However, if A small amount of bpa is not converted into the plastic structure of A PC, it will be released into food or drink. Therefore, special care should be taken when using this plastic container.