Water-soluble plastic packaging film as a novel green packaging material 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, washing Agents, concrete additives, photographic chemicals, and gardening chemicals. Its main features are: complete degradation, degradation of the final product is co2 and h2o, can completely solve the packaging waste disposal problems; safe and convenient to use, to avoid direct contact with the packaged goods, 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 a substance required for an active bacterium of pva. The oxidation of secondary alcohol catalyzes PVA, and then the hydrolase cleaves the oxidized pva backbone and further degrades, eventually degrading 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, as in the United States. t. p company and c. c. i. P company, France's greensol company and Japan's synthetic chemical company, its users are also some well-known big companies, such as bayet (Bayer), henkel (Henkel), shell (shell), agr. Large companies such as Eva (Egford) have begun to use water-soluble film 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. .
Research on other ecological plastic packaging
1. Development of lightweight, thin film, high quality plastics. In order to reduce the total amount of plastic packaging waste, various countries have actively promoted thin film and improved their quality. Japan has developed a super tough ultra-thin pet film with a thickness of 0.5 micron for packaging of precision electronic components. Finland has developed an opa/pe composite film that has been reduced in thickness by 1/3 without affecting other properties.
2. Develop recycled plastics that can be recycled. If plastic packaging materials can be reused, the consumption of raw materials and the pollution to the environment can be greatly reduced. For example, the use of pet bottles, pet bottles are crushed and then blown into new bottles. There is almost no change in physical, chemical, and synthetic mechanical properties. Polyethylene naphthalate (pen) is more heat-resistant than pet, can withstand the sterilization conditions required for low-acid foods, has better gas barrier properties and UV protection, can replace glass bottles, and can be reused. Wide application.
3. Develop new foam plastics. As foam plastic lunch boxes and cushioning packaging materials are used in small quantities and with huge amounts, people are researching new types of foam plastics. It is now ideal to have methane foam, ps, pp, pet, for food and electronics packaging. The highly efficient fluorine-free instapack polyurethane foaming agent developed in the United States can be foamed with a small amount of material, can be reshaped and used, and can be easily handled. The current development of high melt strength polypropylene (hmspp) and polypropylene homopolymers can produce foamed polypropylene, which can save 20% of the raw material and the environmental load of the same performance polypropylene sheet.
2. Natural biological packaging materials
The use of natural biological resources to develop packaging materials has the characteristics of low environmental load and abundant resources. Making full use of raw materials such as bamboo, sawdust, hemp, cotton fabrics, wicker, reeds, crop straws, rice straw, and wheat straw chitin, etc., expanding the variety of packaging and increasing the technological content have become one of the directions of the ecological package.
For example, rice straw processed into rice straw has the functions of energy saving, heat preservation, heat insulation, sound insulation, etc., good air permeability, high impact strength, and significantly higher water and shock resistance than traditional materials; in addition, straw boards are used as packaging materials. Its unit mass is 1/10 of the same volume of cardboard material, which has obvious advantages; in China, a polystyrene foam lunch box substitute using rice straw as raw material is developed; Puffleaves can be manufactured by heat-setting, bleaching, and sterilization. , subject to the attention of foreign importers.
In addition to rice straw, domestic straw pulp was used as the main raw material to develop disposable cardboard. It uses chemical additives to improve the quality of straw pulp to optimize the application technology to ensure that the straw is close to the physical properties of the wood pulp needed to make the cutlery board. The surface is then processed to suit the food packaging, so that the finished product is resistant to hot water. , no leakage, no stratification, oil resistance and heat sealing functions. And can be recycled to produce writing paper.
Natural chitin is also a very good raw material. Each year, the global biosynthetic chitin reaches tens of billions of tons, and the output is second only to natural cellulose. It is the second largest bio-polymer resource on earth. The packaging material prepared by chitin processing has good air permeability and good water absorption and moisture retention. Because the raw materials come from natural, non-toxic, odorless, and heat-resistant, they can meet the hygienic requirements for packaging materials in food, health, and pharmaceutical industries. The material also has good chemical stability, light resistance, chemical resistance, oil resistance, organic solution resistance, cold resistance, etc., and its stability is superior to paper.
(to be continued)
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