Industrial paper began as a food packaging material in […]
Industrial paper began as a food packaging material in the early 20th century. Paper containers made of paper and aluminum foil and plastic composites appeared in the 1950s. Due to the development of aseptic packaging technology and packaging machinery, paper containers have developed rapidly since the 1970s. Paper and paper containers account for the largest proportion of food packaging materials. In developed countries such as the United States and Western Europe, paper and cardboard account for 40-50% of the entire packaging material, of which more than 17% are used for food packaging. Paper containers have the advantages of being lightweight, inexpensive, and easy to handle, with the disadvantage of poor heat resistance and sealing. The new paper containers currently being developed can be used for retort sterilized paper cans and foldable transport paper shields.
Basic Materials The basic materials used for paper containers are: 1 kraft paper, which is made from kraft pulp of cork coarse fiber. Its strength is higher than that of ordinary paper, and it can be used as a large paper bag for sugar, flour and rice. Kraft paper treated with synthetic resin has the characteristics of moisture and oil resistance. 2 sulfuric acid paper, which is treated with sulfuric acid to form a gelatinous starch cellulose on the surface of the fiber, which has the characteristics of high strength, moisture resistance, oil resistance and heat sterilization temperature. It can be used for the packaging of oily foods, frozen foods, and sometimes as a lining of canned paper. 3 wax paper, which is treated with low melting point paraffin, has the characteristics of moisture resistance, oil resistance and sealing resistance. It is the cheapest packaging material for all kinds of high and low grade foods. 4 cellophane, also known as celluloid, is processed by the treatment of pulp with sodium hydroxide solution. It has the characteristics of high transparency, good heat insulation, grease resistance, beautiful appearance and low price, and is widely used in general food packaging. However, ordinary cellophane has the disadvantage of being highly hygroscopic 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. 5Composite paper, which is a laminate of paper and plastic, aluminum foil, etc., has comprehensive properties and can be used for packaging general foods, frozen foods, beverages and aseptic packaging.
Main types Paper containers come in a variety of forms and materials vary. For example, paper containers made of composite paper have three main types: a four-corner paper bag called a milk carton, a brick paper bag, and a roof type paper bag. It is generally made of polyethylene-paper-polyethylene-aluminum foil-polyethylene 5-layer composite paperboard, which has the insulation against water vapor and oxygen. It can be used for the packaging of liquid beverages such as milk and juice. 2 Paper cups, paper boxes, etc. made of paper and plastic composite materials. It is widely used in the packaging of frozen foods and fast foods, especially paper cups and cartons made of polyethylene-paper-polyethylene, etc. 3 combination cans. The can body is made of composite cardboard, the inner wall is coated with resin, and the bottom cover is made of plastic or metal. Mainly used for the packaging of dry foods. In addition, there are vats made of hardened cardboard for packaging dry powdered foods, cereals, and the like.