Flexible packaging is a very important form of food packaging. However, if the flexible packaging is not properly controlled during the gravure process, it may cause organic solvent residues to exceed standards and threaten people's health. With the gradual improvement of people's living standards and health consciousness, consumers hope that traditional flexible packaging can increase safety, environmental protection, convenience and other needs. Under this demand, food packaging films are derived from many different materials for manufacturing. How are they classified? Today, the editor of Yifu Packaging will introduce the classification of food packaging film materials that are widely used in the market.
Classification of food packaging film materials:
1. Polyethylene (PE) polyethylene also has certain flexibility and strong moisture resistance. It has good chemical stability and is a non-toxic packaging material. Good water and moisture resistance, poor gas and organic vapor resistance, good chemical stability, no reaction with ordinary acids and alkalis at room temperature, slightly poor oil resistance; mechanical tensile and tear strength, flexibility Good, low temperature resistance. Therefore, it is often used in heat-sealing and moisture-proof coatings of composite materials.
2. Polypropylene (PP) Polypropylene is polymerized from propylene. It is a very light plastic with good transparency and gloss. It has good physical and mechanical properties such as tensile strength, hardness and toughness, and good heat resistance. , Can be used continuously at a high temperature of 120 ℃, can be cooked in boiling water. Stable chemical properties, stable to acids, alkalis, salts and many solvents in a certain temperature range. Hygienic and safe, meet the requirements of food packaging. Mainly made of thin film packaging food, suitable for packaging oily food.
3. Polyester (PET) is commonly known as polyester. High transparency and good gloss. Has excellent gas, oil and fragrance retention properties. Rigid and tough, high tensile strength. Good chemical stability, resistant to enoic acid and alkali. The use temperature range is wide, the normal use temperature range is -70 ℃ ～ 120 ℃, and it can be used at 150 ℃ for a period of time. Good health and safety. It is widely used in poultry packaging. PET-based composite film can be used for cooking food packaging.
4. Polyamide (PA) is commonly known as nylon, which has strong gas barrier properties, but has poor barrier properties against water vapor, strong water absorption, and swells with the increase of water absorption, which drastically reduces gas and moisture resistance. Its strength and the stability of the package size are also affected. Its mechanical properties are good, toughness is good, wear resistance, cold resistance, heat resistance is good, the normal use temperature range is -60 ℃ ~ 130 ℃, high temperature resistance can reach 200 ℃. It has stable chemical properties, good printability, and good puncture resistance. The material meets the requirements of food packaging with regard to hygiene and safety. Therefore, it is widely used in food freezing packaging and cooking packaging. Because of its good printability and puncture resistance, most of the refined rice sold in the market now uses nylon packaging bags.
5.Polyvinyl chloride (PVC), poor thermal stability, poor fluidity in viscous flow state, need to add plasticizers to improve performance; gas and oil resistance, gloss higher than PE, generally used for fresh fruit and vegetable packaging.
6. Polyhydroxy fatty acid ester (PHA) is a kind of biopolymer material. It is an intracellular polyester synthesized by many microorganisms. With biodegradability and thermal processing properties of plastics, materials often have high water vapor permeability, which is not good for food preservation. PHA has good gas barrier properties, making it possible to apply it to fresh food packaging for a long time.