There are some differences in the oil resistance of food plastic bags made of different materials, which are analyzed below:
Polyethylene (PE)
Low-density polyethylene (LDPE): has good oil resistance. It has a relatively loose molecular structure and a certain degree of flexibility, which can resist the penetration of grease to a certain extent. However, if it is exposed to a large amount of grease for a long time, the grease may gradually penetrate through the plastic bag. For example, if LDPE plastic bags are used to package oil-containing pastries, the oil of the pastries can be kept from seeping out for a short period of time (e.g., 1 - 2 days), but after placing them for a longer period of time, grease spots may appear on the surface of the plastic bags.
High-density polyethylene (HDPE): better oil resistance than LDPE, HDPE molecular chain arrangement is more compact, higher crystallinity, structural stability, the oil barrier performance is stronger. HDPE plastic bag packaging fried food, placed at room temperature for several days, the situation of oil and grease seepage is relatively small.
Polypropylene (PP)
PP has good oil resistance. Its molecular structure contains methyl, making its chemical stability is high, not easy to be dissolved or dissolved by oil and grease. PP material food plastic bags can be used for packaging a variety of oil-containing foods, such as nuts, fried snacks, etc., can be maintained for a longer period of time the oil of the food does not leakage, and after contact with oil and grease, the performance of the plastic bag changes are small.
Polyethylene terephthalate (PET)
PET has excellent oil resistance. Its molecular structure is regular, highly crystalline and rigid, has a strong barrier to oil and grease. PET material food plastic bags are commonly used in packaging edible oil, sauces and other oil-containing food, can effectively prevent the penetration and volatilization of oil and grease, shelf life will not appear oil leakage or plastic bags eroded by oil and grease phenomenon.
Ethylene - vinyl acetate copolymer (EVA)
EVA is generally resistant to oils and fats. Although EVA has good flexibility and elasticity, but its chemical resistance is relatively weak, oil and grease may produce a certain degree of swelling effect, resulting in a decline in the performance of plastic bags. If EVA plastic bags are used to package oily food, oil seepage may occur in a relatively short period of time, and the plastic bags may become sticky and soft after contact with oil.
Overall, the oil resistance of PET and HDPE is more prominent, followed by PP, LDPE again, EVA oil resistance is relatively poor. In the choice of food plastic bags, if the packaging of oil-containing food, should give priority to the oil resistance of the material, in order to ensure the quality of food and the integrity of the packaging.