The most popular food packaging Composites

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The commonly used food packaging composite material

single-layer plastic film can not fully meet the requirements of commodity protection, commodity beautification and processing. therefore "I don't know that people have developed packaging materials with two or more layers of the same or different packaging materials. This composite material overcomes the shortcomings of a single material and obtains excellent properties that a single material does not have. At present, composite materials have played a major role in food packaging.

I. Basic Structure of composite materials

generally speaking, the outer material of composite packaging materials should have a high melting point, The composite materials used in heat-resistant aircraft are mainly carbon fiber reinforced resin matrix composite materials that are good, not easy to scratch and polish, good printing performance and good optical performance. The commonly used materials include paper, aluminum foil, cellophane, polycarbonate, nylon, polyester, polypropylene, etc

the inner layer material shall have the properties of heat sealing, good adhesion, tasteless, non-toxic, oil resistance, water resistance and chemical resistance, such as polypropylene, polyethylene, polyvinylidene chloride and other heat-resistant plastic materials

the middle layer of composite materials with more than three layers usually adopts materials with good performance and high mechanical strength, such as aluminum foil, polyvinylidene chloride, cellophane, paper, polyethylene, etc

adhesive is applied between layers for bonding. Generally, solvent based thermosetting polyurethane adhesive is used between the outer layer and the middle layer, and modified polypropylene lotion adhesive or specially modified co resin containing carbonyl propylene is used between the inner layer and the middle layer. The adhesive for outer layer requires high bonding strength, simple process and low cost; The adhesive for the inner layer shall be high-temperature resistant, high peel strength, non-toxic, tasteless, without affecting the nutritional composition of the food, and can well maintain the color, flavor and taste of the food

in recent years, foreign countries have developed a long way to spread the degradable materials on the surface of the substrate film. A layer of coating agent needs to be uniformly coated on the surface to improve the air tightness, oil resistance and chemical stability of the packaging materials and make them suitable for a variety of food packaging. Common coating agents include polyvinylidene chloride resin and polypropylene polyvinylidene chloride resin. Coating methods include single-sided coating and double-sided coating

II. Currently commonly used food packaging composite materials

double-layer composite

such as cellophane/polyethylene, paper/aluminum foil, paper/polyethylene, polyester/polyethylene, PVC/polyethylene, nylon/polyvinylidene chloride, polyethylene/polyvinylidene chloride, polypropylene/polyvinylidene chloride, etc

three layer composite

such as stretched polypropylene/polyethylene/non stretched polypropylene, polyester/polyvinylidene chloride/polyethylene, polyester/cellophane/polyethylene, cellophane/aluminum foil/polyethylene, wax/paper/polyethylene, etc

four layer composite

such as cellophane/polyethylene/stretched polypropylene/polyethylene, polyvinylidene chloride/cellophane/polyvinylidene chloride/polyethylene, paper/aluminum foil/paper/polyethylene, etc

five layer composite

such as polyvinylidene chloride/cellophane/polyethylene/aluminum foil/polyethylene, etc

six layer composite

such as polyethylene/paper/polyethylene/aluminum foil/polyethylene/polyethylene, etc

cooking bag

cooking bag is a composite film food packaging bag that can be sterilized at high temperature. It was originally developed by the United States to meet the needs of astronauts. In the 1960s, Toyo can manufacturing company of Japan obtained the patent license and realized mass production. At present, only Japan consumes 500million cooking bags every year. The United States, Germany and other countries are also growing at an annual rate of 10%-20%

compared with glass and metal packaging containers, cooking bags not only can be sealed and sterilized, but also have firm sealing, easy opening, beautiful decoration, light weight, good impact resistance and convenient transportation

cooking bags can be divided into general sterilization bags and ultra-high temperature sterilization bags according to sterilization temperature and storage life

ordinary sterilization bags are generally heated below 121 ℃ for sterilization. The big me is made of two to three layers of composite materials. The service life of food is more than half a year. Ultra high temperature sterilization bags are generally sterilized at 135 ℃. The bag making materials are mostly more than three layers, with aluminum foil sandwiched in the middle. The shelf life is years. Some also use four or five layer composites

the outer layer of the cooking bag is mostly made of polyester film, with a thickness of micron, which plays a role of reinforcement and high temperature resistance; The middle layer material is micron aluminum foil, which is mainly used to isolate gas and moisture and shield light; The inner material is used as a direct contact food in the cooking bag and imported heat sealing. Therefore, the requirements for the inner material must not only meet the packaging hygiene standards, but also have stable chemical properties. Generally, non-toxic polypropylene with a thickness of microns can be used, and polyolefin films such as HDPE can also be used

at present, cooking bags are mainly used to pack canned food, and also used to pack beverages and fruit juices in Japan and Western Europe

reprinted from: packaging world

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