According to the packaging containers used in soft cans on the market at present, they can be divided into three types: bags (commonly known as cooking bags), plates (commonly known as cooking containers) and cylinders. These packaging materials or single layer plastic film, or composite products of plastic film and aluminum foil. The composite film packaging materials used in soft cans include nylon and polyester, polyvinylidene chloride, aluminum foil and ethylene-vinyl alcohol copolymer as barrier layers, polypropylene and special polyethylene as sealing layers. According to the experts in the industry, the raw materials used in composite films have the following characteristics:

Polyester: polyester has excellent transparency, heat resistance and abrasion resistance. The film is twelve and twenty-five microns thick, printed on polyester, and can be used as a cooking bag or dish-shaped container cover.

Nylon: Nylon is indispensable as the base material of soft canned packaging materials, there are mainly two kinds of biaxial stretching and non-stretching. Bi-directional tensile nylon 6 film, not only has excellent heat resistance, cold resistance, but also tear strength and pinhole resistance, can be used with other raw materials together. In addition, nylon 6-6 films are also used to prevent shrinkage and improve strength, but the price is higher than nylon 6.

Polyvinylidene chloride: Polyvinylidene chloride as a single film can also be used in soft cans, can be used as ham, sausage packaging materials, its sealing, ligation, heat shrinkage, gas barrier are excellent.  Polyvinylidene chloride two can also be used as a coating material for nylon, polyester and other membrane materials. Besides, it can also be used as a composite material for cooking bags, and as a high barrier film for high temperature and high pressure sterilization.

HDPE: special HDPE used for soft cans is sold in Japan. Although the film has poor gas barrier, it can be used as a sealing layer because of its excellent tensile strength, elongation, tear strength and sealing adaptability. However, the heat resistance of HDPE is poor, and the highest heat resistance temperature is 120 C. Polypropylene: Polypropylene has good transparency and oil resistance, its heat resistance is better than special polyethylene, so it can be used as cooking bag and cooking container sealing layer. Unstretched polypropylene film or thin sheet is mostly used as sealing layer in soft canned packaging materials.

Aluminum foil: aluminum foil is made of electrolytic aluminium with purity of more than 90%. When used as packaging materials, aluminum foil is the only metal substrate in packaging composite materials. The thickness of aluminum foil used for cooking is 7-15 microns, while the thickness of aluminum foil used for cooking container is 50-130 microns. Aluminum foil is non-toxic, tasteless, has excellent shading, has very high moisture resistance, gas resistance and confidentiality, can be the most effective protection of the packaging, as the packaging material of fatty food is the most appropriate. However, due to the danger of pinholes in the aluminum foil after bending, it is necessary to use plastic film as the outer layer and composite with it.

Most of the packaging materials for soft cans are made of plastic film and aluminum foil. However, due to the different types of packaged food, sterilization temperature and preservation conditions, it is necessary to carefully consider the combination of various raw materials in use.