Development and research of the most popular ecolo

2022-08-02
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Development and research of ecological packaging I. Development of packaging materials the primary stage of packaging materials can be traced back to the recorded history of mankind, when the packaging materials were taken from nature. Later, the production of artificial packaging materials, such as paper, glass, metal, etc., provided better raw materials for packaging. The variety of packaging gradually increased and was widely accepted

the real rise of packaging began with the invention of synthetic materials - Plastics in the 1950s. Plastics have the advantages of light weight, durability, barrier, easy forming, various shapes, and low consumption of resources and energy. They have largely replaced the packaging materials processed by natural resources and promoted the emergence of new packaging machinery. It can be said that modern packaging is developing with the development of plastic industry. The 1960s was a turning point for China's plastics industry from thermosetting plastics to thermoplastic plastics. Composite packaging materials developed in the 1970s and 1980s, such as aluminum-plastic composites, paper-plastic composites, plastic and plastic composites, can replace metal, glass, paper and other packaging materials, improve the barrier, structure and printability of packaging, and make packaging more convenient and safer. Especially in recent years, the production of pet, BOPP, nylon film and aluminized film has effectively promoted the development of plastic packaging materials. Now the development of new technology has promoted the emergence of various emerging packaging

packaging materials gradually occupy an important position in the material industry. According to incomplete statistics, the annual sales of packaging materials in the world is about 50billion US dollars, with more than 5million employees, accounting for 1.5% ~ 2.3% of the gross national product

however, packaging has a short service life and a large amount of use (for example, the strain gauge sensor is the most commonly used force measuring sensor in the United States, which produces 150million tons of municipal waste every year, of which 1/3 is packaging waste. The annual solid waste in Japanese cities is about 50million tons, of which 21million tons are packaging waste), and it is difficult to concentrate, causing serious harm to the urban environment and human body. The white pollution caused by the low recovery rate of plastic film, the release of ozone destroying chemicals when burning, and the destruction of ecological balance have aroused widespread concern in the society

ecological packaging originated from the "our common future" document of the United Nations Commission on environment and development in 1987. It refers to packaging that is harmless to the ecological environment and human health, energy recycling and material recycling, and can promote sustainable development. What ecological materials pursue is not only excellent performance, but also the harmony and comfort with the ecological environment in the whole life cycle of material manufacturing, use, waste and regeneration. Since the 1990s, ecological packaging materials have made great progress

II. Research on ecological packaging

1 Ecological plastic packaging

plastic packaging has many advantages and plays an important role in packaging materials. At the same time, plastics account for a large proportion of packaging waste, about 40%. Its biggest drawback is that it is not easy to degrade and cause pollution. At present, the development of new plastic packaging by scientific researchers is mainly biodegradable plastics and chemically degradable plastics

(1) biodegradable plastics

ideal biodegradable plastics are high molecular materials with excellent performance and can be completely decomposed by environmental microorganisms after being discarded. Paper is a biodegradable material, while synthetic plastics are usually non degradable polymer materials. Biodegradable plastic is a new type of high polymer material which has both the degradability of paper and the high performance of synthetic plastics. The degradation mechanism of biodegradable high molecular (macromolecular) materials has been confirmed: high molecular weight macromolecules are mainly decomposed into small molecular weight fragments by bacteria or their hydrolases, and then further decomposed into carbon dioxide, water and other substances by bacteria. It can be divided into three categories:

polyester produced by microorganisms. It is a microbial fermenting macromolecule. It uses enzymes produced by microorganisms to depolymerize and hydrolyze polyesters that are easy to biodegrade in nature, and then decompose and absorb them to synthesize high molecular compounds. These compounds contain microbial polyesters and microbial polysaccharides. In order to reduce the cost of producing microbial polyester, the research of using plants to synthesize biodegradable plastics is being carried out. The United States and Japan have successively used genetic engineering technology to make some plants directly grow degradable polyester on their branches and leaves. For example, the research group of Michigan State University in the United States has successfully developed synthetic polyester by introducing the genetic genes of the biosynthetic microbial polyester system into plants

natural macromolecules (starch, cellulose, etc.) from plants. The research on the synthesis of biodegradable plastics from starch is very hot at home and abroad. Varna Lambart pharmaceutical company of the United States partially controls the branching degree of starch macromolecular chain by manipulating plant genetic genes, so as to produce biodegradable plastics with cheap starch as raw materials. The company has been promoting the application research of medicinal starch capsules and achieved success. On this basis, they also developed thermoplastic biodegradable plastics with the mixture of starch and biodegradable polymers, and commercialized them under the brand of "novon", associate professor zhongyunfei, School of packaging and materials engineering, Hunan University of technology

chemical synthetic polymers. Biodegradable plastics using chemical synthesis, such as polycaprolactone (PCL), have been used since 1975, but the use is very limited. It is said that 95% of them can be degraded after being buried in the soil for 12 months. PCL and starch blends, PCL and PHBV blends, PCL and nylon 6 blends have been developed. Other biodegradable polyesters based on protein, urea and polysaccharide have also been manufactured, belonging to biodegradable plastics

(2) chemically degradable plastic

water soluble plastic packaging film, as a new green packaging material, is widely used in the packaging of various products in Europe, America, Japan and other countries, such as pesticides, chemical fertilizers in China, pigments, dyes, detergents, water treatment agents, mineral additives, detergents, concrete additives, photographic chemicals and gardening care chemicals. Its main features are: complete degradation, the final products of degradation are CO2 and H2O, which can completely solve the problem of packaging waste treatment; It is safe and convenient to use, avoiding the user from directly contacting the packaged goods, and can be used for packaging goods harmful to human body; Good mechanical properties, heat sealing and high heat sealing strength; It has anti-counterfeiting function to extend the life cycle of high-quality products

the main raw material of water-soluble packaging film is polyvinyl alcohol with low alcoholysis degree. Using the film-forming, water-soluble and degradability of polyvinyl alcohol, various additives, such as surfactants, plasticizers and anti adhesion agents, have been released from the first entity entrepreneurship platform in China. In terms of degradation mechanism, polyvinyl alcohol has two degradation characteristics of water and biology. First, it dissolves in water to form gel solution and infiltrates into the soil, which increases the soil's stickiness, permeability and water retention. It is especially suitable for sand soil transformation. PVA in soil can be decomposed by bacteria isolated from soil, Pseudomonas. The symbiotic system composed of at least two bacteria can degrade polyvinyl alcohol: one is the active bacteria of polyvinyl alcohol, and the other is the bacteria that produce the substances required by the active bacteria of PVA. The secondary alcohol oxidation reaction enzyme catalyzes polyvinyl alcohol, and then the hydrolase cuts off the oxidized PVA main chain for further degradation, and finally it can be degraded into CO2 and H2O

water soluble film has good packaging and environmental protection characteristics, so it has been widely valued by developed countries and has a very good application prospect. For example, Japan, the United States and France have produced and sold such products in large quantities, such as w.t.p and c.c.i.p in the United States, greensol in France and synthetic chemistry in Japan. Their users are also some famous large companies, such as bayet (Bayer), Henkel (Henkel), shell (shell), agr.eva (aegfu) and other large companies have begun to use water-soluble films to package their products. With the support of the science and Technology Department of China Packaging Corporation, Zhuzhou Institute of technology and Guangdong Zhaoqing Fangxing packaging materials Co., Ltd. have jointly developed water-soluble films and production equipment, which have passed the provincial and ministerial appraisal. At present, they have been put into production, and their products are going to the market. (to be continued)

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