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With the continuous advancement of packaging materials, packaging machinery and packaging technology, various packaged foods have appeared in large numbers. Such as bottled food, canned food, frozen food, aseptic packaged food, etc. Today we will mainly explain the paper packaging in food packaging.
The industrial use of paper as a food packaging material began in the early 20th century. Paper containers made of paper, aluminum foil, and plastic composite materials appeared in the 1950s. Due to the development of aseptic packaging technology and packaging machinery, paper containers have developed rapidly after the 1970s. Paper and paper containers account for the largest proportion of the entire food packaging materials. In economically developed countries such as the United States and Western Europe, paper and cardboard account for 40-50% of the entire packaging materials, of which more than 17% are used for food packaging. The advantages of paper containers are light weight, low price, and easy disposal of waste. The disadvantages are poor heat resistance and airtightness. The basic materials used in paper containers are as follows.
1. Kraft paper.
Kraft paper is made from kraft pulp of softwood crude fiber. Its strength is higher than that of ordinary paper, and it can be used as large paper bags for packaging sugar, flour and rice. Kraft paper treated with synthetic resin has the characteristics of moisture and oil resistance.
2. Sulfuric acid paper
Sulfuric acid paper treats paper with sulfuric acid to form gelatinous starch cellulose on the fiber surface. It has the characteristics of high strength, moisture resistance, oil resistance and heat-resistant sterilization temperature. It can be used for packaging oily foods and frozen foods, sometimes as canned food lining.
3. Wax paper
Wax paper is treated with low melting point paraffin wax. It has the characteristics of moisture resistance, oil resistance and sealing resistance. It is the cheapest packaging material for a variety of high- and low-grade foods.
4. Cellophane
Cellophane is made by processing paper pulp after treatment with sodium hydroxide solution. It has the characteristics of high transparency, good heat insulation, grease resistance, beautiful appearance and low price. It is widely used in general food packaging. However, ordinary cellophane has the shortcoming of strong hygroscopicity and is not suitable for food packaging with high water content. The moisture-proof cellophane treated with polyvinyl chloride copolymer and polyvinylidene chloride resin has excellent moisture resistance.
5. Composite paper
Composite paper is a laminated material of paper, plastic, aluminum foil, etc. It has comprehensive performance and can be used for packaging general food, frozen food, beverage and aseptic packaging. There are some types of paper containers made of composite paper.
a. Milk cartons, etc.
Generally, it is made of polyethylene-paper-polyethylene-aluminum foil-polyethylene 5-layer composite paperboard. It has insulation against water vapor and oxygen. It can be used for packaging liquid beverages such as milk and juice.
b. Paper cups, cartons, etc. made of paper and plastic composite materials.
They are widely used in the packaging of frozen foods and fast foods. In particular, paper cups and cartons made of polyethylene-paper-polyethylene are mostly used for ice cream packaging.
