Food packaging materials recycling and environmental protection

Paper, plastic, gold and glass are common packaging materials for the food industry. With the development and progress of science and technology, food packaging materials and containers have also undergone major changes. In recent years, the research and development of various new materials and new materials processing technologies, especially the emergence of new types of polymer materials, have provided a vast world for food packaging. It can be said that as far as modern foods are concerned, there are no unpackaged goods.

However, in cities and population gathering places, the negative impact on the environment caused by all kinds of human food packaging waste, especially plastic packaging waste, is increasing. In China, people nowadays are shopping for food in the bazaar, trade market, or shopping in stores and supermarkets. The stall owners or shop owners are all equipped with plastic vests of various sizes, colors, and advertisements. Bags or plastic gift bags, textile bags. Taking Shanghai as an example, there are about 2.6 million households in the Shanghai area. If each family buys an average of three times and discards five plastic bags each time, about two billion plastic bags will be used in one year! Most of them will be discarded as garbage. In addition, plastic lunch boxes, cutlery, cup trays, beverage bottles, ice cream skins, and small food plastic outer packagings in plastic products are not rotted or degraded after being discarded for more than a hundred years, resulting in a large amount of garbage that is difficult to administer. In addition, the waste of packaging waste cannot be recovered and recycled, which results in the waste of natural resources. In particular, the large amount of wood required by the paper industry is more severe in the destruction of forest resources and ecological environment. In 1995, China produced 12 million tons of packaging paper. If all wood is used, it will require 60 million cubic meters. Therefore, all aspects of packaging materials, from development to production, processing, use, recycling, and waste disposal, must be protected by the ecological environment as a standard, and green packaging should be developed based on the protection functions, convenience functions, and sales functions of the packaging. Materials are the development direction of the food packaging industry. Emphasis on and development of green packaging has been mentioned on the agenda. This paper describes the research and development of paper, plastic, gold and glass packaging materials as follows:

First, paper packaging materials

Since paper products can be recycled after use, a small amount of waste can be naturally decomposed in nature and have no adverse impact on the natural environment. Therefore, the world recognized that paper, paperboard and paper products are green products that meet the requirements of environmental protection. Governance The white pollution caused by plastic can play a positive role. At present, paper packaging materials being researched and developed at home and abroad are: (1) Paper packaging film research and development of high-performance paper packaging film to replace the plastic film commonly used in food packaging, is a very promising green packaging; (2) one-time Paper product containers Paper cups, paper trays, paper bowls, paper lunch boxes and other disposable paper product containers can replace various plastic containers. Waste can be used as a secondary fiber in the paper industry, greatly reducing the pollution of plastics; (3 The use of paper packaging materials developed from natural resources to use other natural resources other than wood for paper packaging materials not only reduces costs, but also saves forest resources and protects the ecological environment. China has been able to use rice straw, wheat straw, hemp, and bagasse to produce better-quality paper and snack boxes. Pulp molded products made from waste pulp replace EPS foams, which have good cushioning properties, and have the advantages of anti-mildew, anti-mildew, and anti-static. Honeycomb sandwich board is also a kind of EPS substitute paper product. It is glued on the upper and lower sides of the paperboard, with a natural honeycomb paper core in the middle. It has very good cushioning performance and mechanical strength and is suitable for packaging valuable and fragile goods. (4) Edible paper products The use of edible packaging materials instead of traditional plastic packaging has become a hot technology in the current packaging industry, effectively solving the contradiction between packaging materials and environmental protection. The products currently researched and developed are edible packaging films with soy protein and starch mixed, which can maintain moisture, segregate oxygen, maintain the original flavor and nutritional value of food; the other is edible packaging film of chitosan, which is from shellfish The chitosan is extracted and combined with the hanging acid to produce a uniform edible film, which has a good preservation effect; and chitosan is used as a raw material, processed into packaging paper, can be used for instant noodles, seasoning products, Bread, food and other packaging, can be directly cooked in the pot, do not have to remove the bag; with shellac and starch mix can be made of water and oil resistant packaging paper or coating for fast food packaging.

Second, plastic packaging materials

Plastic packaging materials belong to the shortest period of use of plastic products. Grade 1 is 1 to 3 months and up to 1 year. Since then, they have mostly become municipal solid wastes entering garbage disposal systems, and some have been discarded at random, becoming “white pollution”. . Plastic packaging materials account for the largest proportion of packaging waste, and their pollution to the environment is also the most severe punishment for all types of packaging materials. The current treatment plan is: the combination of recycling and development of the application of degradable plastics. The main use of recycling, but for the one-time plastic waste drama, it should be treated according to different circumstances, treated differently, easy to recycle and have the value of material recovery, economic and reasonable should be the maximum recovery, on the contrary, the use of degradable plastic is more appropriate .

1. Recycling

(1) PET PET Packaging PET recycling is one of the most widely used materials in the packaging field for 80 years. A large number of PET bottles are put into the market. After consumption, the environment will be greatly polluted and fully recycled. It can save resources and energy, create economic benefits, and should vigorously promote this recycling technology.

(2) The development and application of waste plastics oiling technology is now actively developing this technology in China, and some experimental companies have put into production. China's technology is also actively developed and put into mass production. However, the development of this project must face both technical and economic obstacles; it is difficult to compete with crude oil prices; it needs to be purified to have no hydrocarbon components. In China, the development of pyrolysis liquefaction technology for waste plastics is very active. It is generally referred to as waste plastic oil technology. However, some technologies have been introduced to the market when they are immature, and they will also cause new pollution to the environment. This must be taken seriously. attitude.

(3) The development and application of high-intensity fire-retardant composite intrinsic plastics technology for the production of waste plastics This technology is a new type of composite material made of thermoplastic resin as precursor, added with the cellulose of the material and a variety of chemical additives and mixed at high temperature. . Once the product was introduced, it was popular and achieved a good wood replacement effect.

(4) Production of waste packaging plastics (including PE, PP, PVC and PS) and filler blends (including various urban and rural wastes such as activated carbon waste, crushed animal and plant wastes, weathered coal, etc.) Humic acid and other powders together make up the fertilizer capsule and coat the surface of the fertilizer particles to form a special structure. The whole process of releasing fertilizer, smashing and degrading does not interfere with farming. On the contrary, it also increases the permeability and permeability of the soil.

2. Degradable plastics Degradable plastics are plastics whose chemical structure changes in a specific environment that causes performance loss in a specific period of time. The development of biodegradable plastic packaging materials and the gradual elimination of non-degradable plastic packaging materials are the major trends in the development of science and technology in the world and are one of the hot topics in the research and development of materials. As the biodegradable plastic is easy to process and shape, the price is gradually reduced, resulting in a drastic increase in the use of biodegradable plastics for packaging. In the United States, for example, there are currently more than 40 companies producing biodegradable plastics, and their products have been widely used in food packaging.

The biodegradable plastic packaging material not only has the functions and characteristics of traditional plastics, but can also be used in the use of the mission, through the role of microorganisms in the soil and water, or through the role of ultraviolet light in the sun, splitting and reducing in the natural environment, eventually with no The poisonous form re-enters the ecological environment and returns to nature. Degradable plastics are generally classified into biodegradable plastics, biocleavable plastics, photodegradable plastics, and bio/photodegradable plastics.

(1) Biodegradable plastics Currently biodegradable polymers are biosynthetic fatty polyesters, such as PHB and PHBV synthesized by fermentation, ether and polyhydroxy polymers such as starch and cellulose, and synthetic poly Amides, polyurethanes, packaging materials, and are widely used as packaging films, packaging containers or strapping materials. However, materials such as PHB, PHBV, and polyethers have low melting point and strength, and they are of little use. Microbiologically degradable packaging materials have attracted much attention due to their complete harmlessness to the environment. The development of new varieties and the further development of current varieties will surely promote the era of replacement of packaging materials.

(2) The mechanism of bio-cleaving plastic starch plastics is to make existing plastics and biodegradable macromolecules coexist, resulting in discontinuous plastics. After the starch particles in the plastic are decomposed by microorganisms, only the plastic macromolecular skeleton is left. The plastic macromolecules can oxidize the macromolecule chain into many small pieces of plastic or plastic particles in the soil or in the air through oxidation. Biocleavable plastics can be used in meat, soy products and other food packaging.

(3) Photodegradable plastics are mainly synthetic and additive in the world. It is mainly used in beverage bottles, shopping bags and plastic films in foreign countries. It is mainly used in domestic models and is used only for plastic film and disposable new-style snack boxes. Photodegradation itself is greatly constrained by geography and climate, and it is difficult to achieve a more accurate time control and incomplete degradation.

(4) Bio/photo-degradable plastics Bio/photo-degradable plastics currently entering the market are mainly modified by blending general-purpose polymers such as PE and PP with degradable polymers such as starch or cellulose. The branches were modified and added with a photo-degrading photosensitizer. Research and application in this area are very active. The bio/photo-degradable plastics developed by the Department of Chemistry of Lanzhou University in China can be directly used in the production of fast food boxes and garbage bags.

Third, metal packaging materials

Because metal packaging materials are easy to recycle and easy to handle, their waste pollution to the environment is smaller than plastic and paper. Commonly used metal packaging materials are tinplate and aluminum, which are widely used in the manufacture of food and beverage cans. In recent years, the changes and development directions of metal cans are: (1) to increase the strength of the material, reduce the thickness of the substrate, increase the strength of the material, reduce the thickness of the substrate, can save the amount of metal materials, reduce the cost, and reduce the cost. (2) Reduce the tin plating volume of tinplate; (3) Use tinplate as an aluminum can, because of the high value of aluminum and the unstable value, various countries have used tinplate instead of aluminum to produce two-plate cans for food. , beverage cans; (4) using resistance welding, to achieve lead-free pollution; (5) the use of aluminum foil instead of plastic and paper because aluminum foil recycling is very easy, almost no pollution to the environment, so the use of aluminum foil instead of plastic and paper is a good development direction. Many foods can be packaged in containers made of aluminum foil.

Fourth, glass packaging materials

Milk, soft carbonated drinks, alcohol, and jams are commonly packaged in glass containers. Some cooking utensils and cutlery are also packaged in glass. The main features of glass packaging materials are aesthetics, hygiene, corrosion resistance, low cost, and are inert materials, with little pollution to the environment; their disadvantages are fragile and bulky.

From the perspective of the development of foreign glass packaging materials, glass bottles for food packaging have been developed in the direction of increasing glass strength and light weight (thin-walled). Lightweighting and thinning will inevitably affect the strength of the glass container. In addition to adopting a reasonable structural design, the solution to this problem is to use chemical and physical strengthening techniques and surface coating strengthening methods to improve the physical properties of the glass. strength.

V. Conclusion

Due to the development of modern food technology and packaging materials, packaged foods can be consumed by people whenever and wherever they are needed, and they are very popular among consumers. However, traditional food packaging materials, especially plastic products, have caused great harm to the environment. Therefore, research and development of environmentally friendly packaging and recycling of packaging waste are an important part of purifying human living space.

(Liang Sha, Industrial Design Department, Yunnan University of Technology)