To protect the environment and develop green packa

2022-08-04
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Protecting the environment - developing green packaging materials

[Abstract] this paper introduces the current situation of the use and recycling of packaging materials, and expounds the use of packaging materials and the recycling of packaging waste according to the connotation of green packaging, so as to coordinate the development measures

[key words] green packaging; packaging; Packaging waste recycling

"green packaging" has two meanings: -- the whole packaging process will not cause pollution and damage to the ecological environment and human health—— The packaging materials used must be renewable and sustainable

the concept of green packaging originated from the spread of white pollution in the last century. To control white pollution is to promote the rational use of the type and quantity of packaging materials and the effective recycling of packaging waste

I. green packaging materials and classification

green packaging materials are recyclable packaging materials that are harmless to human health, have a good protective effect on the ecological environment, and can be recycled in the packaging materials we produce, manufacture, use and recycle. For example, polypropylene, corrugated paper, edible glutinous rice paper, corn paper, edible recycled fresh-keeping paper, and our daily paper packaging products, paper handbags, paper cups, paper lunch boxes, etc

the new green packaging materials (degradable materials) that have been vigorously researched and developed worldwide are all proposed for the "white pollution" that is difficult to deal with. Therefore, green packaging materials can be roughly divided into three categories according to environmental protection requirements and the attribution of materials after use

first, recyclable materials. Including paper, paperboard materials, molded pulp materials, metal materials, glass materials, common linear polymer materials (plastics, fibers), and degradable polymer materials

second, materials that can be naturally weathered and returned to nature. Including: - paper product materials (paper, paperboard, molded pulp materials)—— Degradable materials (photodegradation, biodegradation, oxygen degradation, light/oxygen degradation, water degradation) and biosynthetic materials, grass, straw filling, shell filling, natural fiber filling materials, etc—— Edible materials

the third is quasi green packaging materials, which can be recycled and incinerated, do not pollute the atmosphere and are introduced as energy renewable materials. Including some linear polymers, shape polymer materials that cannot be recycled, and some composite materials (plastic/metal, plastic/plastic, plastic/paper), etc

II. Development of green packaging materials

1 Green packaging and printing paper

among the four packaging materials of paper, plastic, metal and glass, paper products have the fastest growth. The International Health Organization and domestic environmental protection experts believe that waste plastics may cause white pollution, which is not conducive to environmental protection. Therefore, the use of plastic food bags should be gradually prohibited, and it is required to use environmentally friendly paper bags for packaging. In the future, non-toxic and harmless "paper environmental protection bags" should be used for shopping

paper packaging materials are not only rich in resources, easy to recycle, but also easy to degrade. After the paper products are decayed, they can not only recycle recycled paper or be used as plant fertilizer, but also reduce air pollution and purify the environment. Therefore, another important sustainability feature of aluminum, a plastic material that entered the market early and has advanced technology, is its recycling capacity, metal and glass packaging. Compared with other three major packaging materials, paper packaging will become one of the most promising green packaging materials by using the "ecological cycle assessment" technology for quantitative assessment. Cartons, paper bags, paper barrels and pulp molded products have become an important part of modern packaging industry. At present, the output of paper and paperboard is increasing year by year. Packaging paper and paperboard account for more than 50% of the total output of paper and paperboard in China. The per capita consumption of paper has become an important symbol to measure the level of economic development and civilization of a country in the world. In the proportion of materials used for packaging products in the world, the use of paper ranks first

many Japanese paper-making enterprises have researched and produced green packaging printing paper for the printing and packaging field, which has activated the green packaging product market. Nippon Paper Co., Ltd. of Japan has developed a deep stamping paper, which is completely made of natural fiber and named "npimold paper", and its elasticity is 5 ~ 10 times that of ordinary paper. The stamping paper can press characters, patterns and three-dimensional curved surfaces during molding, which is similar to the processing of plastic products. Smooth convex image processing can achieve better sealing. The production of this product can adopt the current plastic product equipment and be molded according to the design scheme. Because there is no need to heat and soften before processing, it can improve production efficiency and save energy. Challenge five Co., Ltd. launched biodegradable films and envelopes produced by MIT subishi. The film and envelope are also produced from polylactic acid extracted from corn starch, and can be offset printed with soybean ink. Dynic Co., Ltd. has developed a biodegradable soft board "aupaircornsheet" with corn starch and fatty polyester as raw materials, with the goal of eventually replacing PVC. This material is easy to cut and print, and its thickness can be adjusted according to the use requirements. The waste landfilling treatment will not pollute the environment, and the incineration treatment will not produce toxic substances such as dioxin due to its low calorific value, so it has little harm to the environment

the latest application market of new paper packaging is wine packaging. For example, it is now popular in Japan to replace glass bottles with carton packaging as wine packaging. Western countries also use paper materials to pack wine and fill wine into Tetra Pak sterile brick cartons. This Tetra Pak bag has the advantages of safety, quality assurance, non fragile and non explosive, and is easy to carry and open. In addition, one of its outstanding features is that it is composed of 6 layers of composite materials, which not only strengthens the sealing, but also enhances the anti alcohol leakage and volatilization of the packaging; At the same time, it can block direct sunlight to avoid deterioration. Recently, Japan has also developed a composite carton for cooking oil, which is made of 6 layers of aluminum-plastic composite with paper as the base material. Its structure is pe/paper/pe/al/pet/pe. The package is not only light and safe, but also suitable for printing

a Japanese company has developed a kind of packaging paper with dehydration function without heating or additives - PS packaging paper. By absorbing water along the intercellular space, it can not only absorb the water on the surface of food, but also absorb the deep water inside. It also has the function of absorbing water at low temperature. In this way, the wrapping paper can inhibit the activity of enzymes, prevent protein decomposition, reduce microbial reproduction, and achieve the effects of maintaining food freshness, concentrating fresh ingredients, removing moisture, and improving toughness. Using the packaged fish and meat as dishes can reduce the heat energy for heating, prevent the deterioration of the heating oil, facilitate conditioning and processing, and do not lose the freshness due to freezing. The mechanism of the packaging paper is that a semi permeable membrane that can only penetrate water is selected as the surface material, and a high osmotic pressure material and a high molecular absorbent are placed on the inner side. Because of the osmotic pressure difference in the liquid state of water in food, it can move to the high osmotic pressure material through the semi permeable membrane. Therefore, these water is fixed by the polymer absorbent

paper materials have always been regarded as environmentally friendly materials, so we can follow a recent media report on recycling. However, some paper packaging materials add other substances to improve the strength, which affects the reproducibility. A kind of special packaging paper for plmex food is popular in Europe and America, which does not contain fluorescent agents and chemicals harmful to human body. Plmex made of paper has the characteristics of water resistance, oil resistance, adhesion resistance and heat resistance, and can be washed and reused with clean water after use. It can be used up to 50 times. BASF Chemical Group has also developed a protective coating applied to the surface of packaging paper. The packaging paper coated with polymer dispersion is water-resistant, moisture-resistant, oil-resistant and grease resistant, and can be manufactured without changing the existing production process, without affecting the recycling effect

2. Polylactic acid packaging material

polylactic acid has become a worldwide research and development hotspot. It is a new biodegradable polymer material polymerized by many lactic acid molecules, which can be completely decomposed into water and carbon dioxide without any harm to the environment

In November, 2004, Shanghai Xinli Industrial Microbiology Technology Co., Ltd. and the school of materials science and engineering of Tongji University successfully developed degradable poly (lactic acid) materials, which were listed as a major industrialization project of revitalizing Shanghai through science and education

the United States, France, Japan and other countries have developed and utilized corn, sugarcane, sugar beet, potato and other agricultural and sideline products as raw materials to ferment lactic acid and then produce polylactic acid. The process of manufacturing biodegradable plastics from corn by LLC of the United States is as follows: firstly, the corn is ground into powder, and the starch is separated, and then the original glucose is extracted from the starch. Lactic acid is produced by anaerobic fermentation with Lactobacillus. The fermentation liquid is neutralized with liquid alkali to produce lactic acid. After purification, L-lactic acid with purity of 99.5% is prepared by electrodialysis process. Then the extracted lactic acid is made into the final polymer - polylactic acid. The global annual output of 600 million tons of corn makes it the preferred raw material for biodegradable plastics

the United States collegefarm brand candy packaging adopts biodegradable resin polylactic acid film. The film has crystalline transparency, excellent kink retention, printability and strength, and high barrier, which can better retain the flavor of candy. A German company successfully developed a green food cup with rapid natural decomposition function using polylactic acid as raw material, which opened up a new practical way to solve the problem of degradation of disposable plastic packaging in the past

3. Natural biological packaging materials

natural biological packaging materials, such as wood, bamboo weaving materials, sawdust, hemp cotton fabrics, wicker, reed, straw, wheat straw, etc., are easy to decompose in the natural environment, do not pollute the ecological environment, and have renewable resources and low cost. For example, bamboo packaging products can be reused, and waste can be incinerated to use heat; Compost is rotten and can be used as fertilizer; Waste can degrade naturally. Bamboo plywood is an excellent green packaging material because of its high strength, low price, light weight, easy recycling of waste and no environmental pollution

4. Environmental friendly packaging of food waste according to New Scientist magazine, biochemists of Hawaii natural energy research institute have made food waste into a biodegradable polymer, which researchers playfully call "perfect plastic". This kind of plastic that can be degraded in a short time is widely used. It can not only be used to make bottles, bags and other packaging materials, but also be made into capsule coats of drugs. According to the biochemist of the natural energy research institute, the raw material of the new degradable plastics is the mixture of water and various food wastes. Each 100kg mixture can produce 22 ~ 25kg of degradable plastics, greatly reducing the production cost

III. measures to promote the development of green packaging materials

1 The development of green packaging materials involves many high and new technologies. Industrial developed countries have studied fully biodegradable plastics for several years, but so far there are not many real industrialized products, which involves many problems of experimental research and industrial production. The development of green packaging materials needs the cooperation of industrial enterprises, scientific research institutes and universities. Therefore, the development plan of green packaging materials for 5 ~ 10 years should be formulated, and the main research and development projects and objectives should be put forward, such as high-performance, low-cost pulp molding disposable catering

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