Research and Application of Ecological Packaging Materials (I)

[Abstract] This article discusses the importance and necessity of developing ecological packaging materials from the perspective of ecological protection and sustainable development. It summarizes the current research status of ecological materials in the world, plastic ecological packaging, edible packaging, natural biological packaging, and paper Packaging, nano-plastics, etc., analyze the future development direction of packaging materials.

[Key words] packaging materials, ecological research, nanoplastics

First, the development of packaging materials

The primary stage of packaging materials can be traced back to the history of human records, when the packaging material was taken from nature. After the production of man-made packaging materials, such as paper, glass, and metal, they provided better raw materials for packaging, and the varieties of packaging gradually became more popular and 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 properties, easy molding, various shapes, and low resource and energy consumption. They have largely replaced packaging materials processed by natural resources and promoted the emergence of new packaging machinery. It can be said that modern packaging has developed with the development of the plastics industry. The 1960s was the turning point of China's plastic product industry from thermosetting plastic products to thermoplastic plastic products. Composite packaging materials that were developed in the later seventies to eighties, such as aluminum-plastic composites, paper-plastic composites, and plastic-plastic composites, can replace metal, glass, paper, and other packaging materials, improving the barrier properties of packaging. , Structure, printing, make packaging more convenient and safer. Especially in recent years, the production of PET, BOPP, nylon film, and aluminized film has strongly promoted the development of plastic packaging materials. The development of new technologies has now promoted the emergence of a variety of emerging packaging.

Packaging materials gradually occupy an important position in the material industry. According to incomplete statistics, the world's annual sales of packaging materials are about 50 billion U.S. dollars, employing more than 5 million people and accounting for 1.5% to 2.3% of the GNP.

However, the packaging has a short life span and a large amount of usage (for example, in the United States, 150 million tons of municipal waste is generated each year, of which 1/3 is packaging waste. The solid waste in Japanese cities is about 50 million tons per year, of which packaging waste is 21 million tons) and it is difficult to concentrate, causing serious damage to the urban environment and the human body. The white film pollution caused by the low recovery rate of plastic films, the release of chemical substances that destroy the ozone layer during incineration, and environmental problems such as the destruction of ecological balance have caused widespread concern in the society.

Eco-packaging originated from the "Our Common Future" document of the United Nations Environment and Development Committee 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. The eco-materials pursue not only excellent performance but also the coordination, co-existence and comfort of the eco-environment throughout the entire life cycle of the production, use, and disposal of the materials. Since the 90s of last century, ecological packaging materials have been greatly developed.

Second, the study of ecological packaging

1. Ecological plastic packaging

Plastic packaging has many advantages and occupies an important position in the packaging material. 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, researchers are developing new types of plastic packaging, mainly biodegradable plastics and chemically degradable plastics.

(1) Biodegradable plastic The ideal biodegradable plastic is a polymer material that has excellent performance and can be completely decomposed by environmental microbes after disposal. Paper is a biodegradable material, and commonly used synthetic plastics are non-degradable polymer materials. Biodegradable plastic is a new polymer material that combines the degradability of paper with the high performance of synthetic plastics. Biodegradable macromolecule (macromolecule) materials have been proven to have a degradative mechanism: high-molecular-weight macromolecules are mainly decomposed by bacteria or their hydrolytic enzymes into smaller molecular weight fragments, which are then further decomposed by bacteria into carbon dioxide and water. Can be divided into three categories:

Microbial produced polyester. It is a microbial fermentation-type macromolecule, which uses enzymes produced by microorganisms to depolymerize and hydrolyze polyesters that are easily biodegradable in nature, and then decomposes and absorbs synthetic polymer compounds. These compounds contain microbial polyesters and microbial polysaccharides. In order to reduce the cost of manufacturing microbial polyesters, research is being conducted on the use of plant synthetic biodegradable plastics. 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 introduced genetic genes of biosynthetic microbial polyester systems into plants. Synthetic polyesters have been successfully developed.

Natural polymers (starch, cellulose, etc.) derived from plants. The development of this starch synthetic biodegradable plastic at home and abroad is very hot. Wana in the United States. Lambert Pharmaceuticals, by manipulating the genetics of plants, partially controls the degree of branching of starch macromolecule chains, thereby producing biodegradable plastics using cheap starch as raw material. The company has been promoting the application of medicinal starch capsules and has achieved success. On this basis, they also developed thermoplastic biodegradable plastics using a mixture of starch and biodegradable polymers, and commercialized them under the brand name “NOVON”.

Chemically synthesized polymers. The use of chemically synthesized biodegradable plastics, such as polycaprolactone (PCL), has been used since 1975, but it has been used very limitedly. It is said that it can be degraded by 95% after being buried in soil for 12 months. PCL and starch blends, PCL and PHBV blends, PCL and nylon 6 blends have been developed, and other biodegradable polyesters based on protein, urea and polysaccharides have also been produced. They are biodegradable plastics. .

(2) Chemically degradable plastic Water-soluble plastic packaging film is a novel green packaging material that is widely used in the packaging of various products in Europe, America, Japan and other countries, such as pesticides, fertilizers, pigments, dyes, detergents, water treatment Agents, mineral additives, detergents, concrete additives, photographic chemicals, and gardening chemicals. Its main features are: complete degradation, the final product of degradation is CO2 and H2O, can completely solve the packaging waste disposal problems; safe and convenient to use, to avoid direct contact with the packaged material, can be used for the packaging of harmful substances; Good mechanical properties, heat sealable, high heat sealing strength, anti-counterfeit function, prolong life cycle of high quality products.

The main raw material of water-soluble packaging film is polyvinyl alcohol with low degree of alcoholysis, using polyvinyl alcohol film-forming, water-soluble and degradable, add various additives, such as surfactants, plasticizers, anti-sticking agents, etc. . As far as the degradation mechanism is concerned, polyvinyl alcohol has both water and biological degradation characteristics. It first dissolves in water to form a glue solution and penetrates into the soil, which increases soil stickiness, air permeability and water retention, and is particularly suitable for sand soil remodeling. The PVA in the soil can be decomposed by the strain of bacteria Pseudomonas isolated in the soil. A symbiotic system composed of at least two bacteria can degrade polyvinyl alcohol: one is an active bacterium of polyvinyl alcohol, and the other is a bacterium that produces substances required for PVA-active bacteria. The oxidation of secondary alcohol catalyzes PVA, and then the hydrolase cleaves the oxidized PVA backbone, further degrades, and eventually degrades to CO2 and H2O.

The water-soluble film has better packaging characteristics and environmental protection characteristics, so it has received extensive attention from developed countries and has a very good application prospect. For example, Japan, the United States, and France have mass-produced and marketed such products, such as the United States’ W. T. P company and C. C. I. P company, France's GREENSOL company, and Japan's synthetic chemical company, its users are also some famous big companies, such as Bayet, Henkel, Shell, Agr. Large companies such as Eva have started using water-soluble films to package their products. Domestic Zhuzhou Institute of Technology and Guangdong Zhaoqing Fangxing Packaging Materials Co., Ltd., with the support of the Ministry of Science and Technology of China National Packaging Corporation, have jointly researched and developed water-soluble films and production equipment. They have passed provincial and ministerial level appraisal and are currently in production. Their products are moving into the market. .