Bags are closely related to our lives, and are now widely used. Here is a brief introduction to several types of bags.
First of all, let's introduce the food packaging bag: it refers to the film container used to hold and protect food in direct contact with food. Food packaging bag should use food grade plastic film for production, generally divided into two layers of composite material packaging bag.
A qualified food packaging bag should be marked with the following information: the name of the food, food ingredients, nutritional components, executive standards, shelf life, storage methods, edible methods, manufacturer information, etc.
Food packaging bags can be divided into general food packaging bags, vacuum food packaging bags, inflatable food packaging bags, boiled food packaging bags, steamed food packaging bags and functional food packaging bags according to their application scope and use.
The general production process of food packaging bag is as follows:

Plan ← → design ← → printing ← → compound ← → aging ← → slitting ← → bag making ← → quality inspection ← → finished products

1: Aluminum foil bag

Aluminum foil bag packaging bag usually refers to aluminum plastic composite vacuum packaging bag. This kind of product is suitable for moisture-proof, light proof and vacuum packaging of large-scale precision mechanical equipment, chemical raw materials and pharmaceutical intermediates. Most of them adopt four layer structure and have good water and oxygen isolation functions. It can be made into flat bag, stereo bag, organ bag and so on.

2: Cooking bag

Compared with canned food, cooking bag food uses flexible packaging materials and vacuum packaging with reserved capacity without air to form a compact and thin packaging state. It can be called soft can.
The cooking bag requires high temperature cooking above 121 ℃ to kill the sheath, and it can be kept for a long time at normal temperature. Therefore, the required functions are as follows:
1) Good air and moisture resistance, good mechanical strength, heat resistance; 2) good hygiene, no odor, good oil resistance; 3) good cooking resistance, size is not disordered after cooking; 4) good heat sealing property; 5) good printing property, good cooking resistance of printing ink, less residual solvent, no discoloration; 6) good filling, good pinhole resistance and cold resistance; 7) opaque bag has a year or more 8) beautiful appearance.
3: Vacuum bag
Vacuum bag, also known as vacuum packaging, is based on the principle of atmospheric pressure. The main function of vacuum bag is to remove oxygen, so as to prevent food from spoilage. Vacuum packaging is a process in which the oxygen in the packaging bag and food cells is pumped out with an air extractor, which makes microorganisms lose their "living environment". Vacuum bag can also prevent food oxidation, make food taste unchanged, deterioration, reduce the loss of vitamin A and C.

Vacuum packaging materials are usually made of double-layer composite film or three-layer aluminum thin composite film. There are two types of vacuum packaging machine: cavity type and external suction type. China's vacuum packaging technology was developed in the early 1980s, and the vacuum inflatable packaging technology began to be used in the early 1990s.
Vacuum inflatable packaging is to extract the vacuum, and then fill in nitrogen, carbon dioxide and other gases. Nitrogen is an inert gas, which plays a filling role and keeps the vacuum bag under positive pressure, so as to prevent the air outside the bag from entering the bag and protect the food. Carbon dioxide can inhibit the activity of microorganisms such as mould sheath and rotten thin sheath. Some foods, such as crisp and fragile food, easy to deform and take oil, sharp edges and corners or high hardness will puncture the vacuum bag. After vacuum inflatable packaging, the filling pressure in the vacuum bag is stronger than the atmospheric pressure outside the packaging bag, which can effectively prevent food from crushing and deformation under pressure, and does not affect the appearance of the packaging bag and printing decoration. With the promotion of small vacuum bag packaging and the development of supermarkets, its scope of application will be more and more extensive, some will gradually replace hard packaging.