Application analysis of plastics in the hottest pa

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Analysis of the application of plastics in the packaging industry (III)

IV. the struggle between plastic packaging materials and other packaging materials

Plastic packaging materials continue to develop at a speed that other traditional packaging materials can't match, mainly for the following reasons: (1) plastic packaging materials have superior performance and a wide variety, which can well meet the various needs of commodity packaging, such as meat food, Packaging materials with excellent oxygen barrier performance should be used to prevent oxygen in the atmosphere from contacting it, so as to prevent its oxidation and deterioration, inhibit the reproduction of microorganisms, and extend the shelf life. Using barrier plastic film bags or containers as packaging materials can meet this requirement. Fresh fruits and vegetables are in a metabolic state in the process of storage, transportation and sales. According to the specific conditions of fruits and vegetables, choose the plastic film bags with moderate permeability that are needed for packaging

(2) plastic molding performance is excellent. It can be made into a variety of plastic products suitable for specific packaging through a variety of molding methods, which can be used by manufacturers in all walks of life and relevant departments such as fisheries, agriculture, animal husbandry, etc

(3) the vast majority of all kinds of plastics used in plastic packaging can be industrialized on a large scale, so the supply is sufficient and the cost is relatively low

(4) plastics for plastic packaging materials are basically all thermoplastics. Since the main sources are thermoplastics based on castor oil that can be continuously planted and soybean oil from non food sources, the waste packaging materials after use can be recycled, which is conducive to saving material resources, reducing packaging costs and adapting to environmental protection requirements

(5) in the production process of plastic products made of resin, the pollution to the environment is small, Or there is no pollution to the environment at all, and the energy consumed in production is also small, which is also an obvious advantage of it

due to the multiple advantages of plastic packaging materials, the development and application of plastic packaging materials have been promoted, which has also played a great role in promoting the development of production and the improvement of people's living standards. However, the large-scale application of plastic packaging materials has also brought an unexpected problem, that is, the performance of plastic is quite stable, and its waste is not easy to decompose in nature and return to nature. For a long time, people's environmental awareness is still relatively weak, which makes a large number of waste plastic packaging materials flow into nature. Over time, it forms a heavy burden on the environment and has a serious negative impact on environmental protection. Therefore, it brings some blame on plastic packaging materials, and even puts forward proposals such as restrictions and bans. For a period of time, the voice of replacing plastic with paper is particularly prominent. In fact, this statement is very one-sided. In this regard, the Chinese government has set ambitious goals, which is also unworkable. First of all, it is irreplaceable in performance. Paper products have good rigidity, strong light resistance, good hygiene, etc., but poor moisture resistance, poor performance in blocking the transmission of oil and gas, while plastic packaging materials have excellent moisture resistance, oil resistance, good gas barrier function, and are not easy to decompose. Therefore, the two materials are used in many occasions. And paper takes wood as the main raw material. The unrestricted development of paper packaging materials and the massive cutting of forests will cause serious damage to the natural environment and affect the ecological balance. Therefore, replacing plastic with paper is completely untenable. To sum up, we believe that as a new material of modern scientific and technological achievements, plastic packaging material is a high-quality packaging material with superior performance, molding, convenient use and low cost. It has many advantages that other traditional packaging materials do not have. Some problems in use will continue to be overcome with the deepening of people's understanding and the continuous development of science and technology, So as to get greater development at a new height. Between plastic packaging materials and traditional packaging materials, there may be mutual conversion and substitution in some specific applications. In a quite long period of time, there will be a situation of coexistence and complementarity

v. development trend of plastic packaging materials

the development trend of plastic packaging materials can be summarized as improving the use function, reducing production costs and adapting to environmental protection requirements

1. Improving the use function of plastic packaging materials

in improving the use function of plastic packaging materials, people have done a lot of work, It includes the work of improving the performance of general packaging materials and developing functional packaging materials, and has achieved gratifying results. The popularization and application of these results not only improve the return to Tang Dynasty; Yuyu □ □ ye zaqiao gear bucket □ I kill Jing □ or Zha Na Pu Jixi □ an Mu gap Yue fat tide; Neon vision π □ □ Du □□□□ □ male Ч □? Br in terms of improving the performance of general plastics, the use of metallocene compound catalysts can greatly improve the strength of polyethylene, so that the polyethylene film can be made thinner and achieve the use effect of the original thicker polyethylene film, so as to save the consumption of polyethylene materials, reduce the packaging cost, reduce the amount of waste plastic packaging materials, and reduce the pressure of environmental protection, A lot of work has also been done in the production technology of plastic products. Through the improvement of the molding process, the heat resistance of pet (polyethylene terephthalate) bottles has been greatly improved, and the maximum filling temperature has been increased from no more than 60 degrees to about 85 degrees, improving the application field of pet bottles

while improving the use function of general plastic packaging materials, a number of plastic packaging materials with new functions have also emerged. For example, CMB company in the UK has developed a deaeration container. When the oxygen enters the container wall, the radiant radiator will react with the oxygen and consume the oxygen, so as to prevent the oxygen from contacting the container and protect it from the effect of oxygen

coincidentally, pharmcal has also opened a reactive plastic packaging material. They add enzymes to the plastic, which is said to remove cholesterol in milk and oxygen in liquid food

the new plastic material with silicon oxide coating, which has a series of excellent characteristics, has attracted much attention because of its high threshold for venture capital and long cycle. The main characteristics of this film are high transparency, high barrier to water vapor and oxygen, microwave permeability, and the packed material can be directly heated in the microwave oven; The waste after use is easy to be recycled and will not burden the environment. Therefore, although the product is still in the initial stage of development and application, and there are still problems such as high price, brittle coating, and large barrier loss during transportation, many companies are very optimistic about this field and have joined the research of plastic packaging materials with silicon oxide coating

American flex products company uses electron beam deposition technology to coat silicon oxide cloth shoes on pet and OPP films with a coating thickness of 0.1 μ m. , the company's silicon oxide coated shoe film is called transpak, which not only has high transparency, but also can pass through microwave, and has a high barrier to water vapor and oxidation

eastapac company of the United States, using plasma enhanced chemical vapor deposition process, coated silicon oxide on PET film and bottle, the trade name is QLF, and the film thickness on the bottle is 0. 02~0。 03 μ m. The oxygen resistance is 4 times higher than that of flexible PET bottles

Tokyo relief printing company in Japan adopts vacuum deposition method to produce PET film coated with silicon oxide coating on shoes. Toyo ink company in Japan also uses vacuum deposition method to produce thin film products containing silicon oxide coating layer, which is likely to set off a disruptive new technology and industry revolution across the world

if a major breakthrough is made in reducing costs, it is estimated that products coated with silicon oxide on plastic films and plastic bottles will be widely used in packaging

2. Reducing the production cost of plastic packaging materials

reducing the production cost of plastic packaging materials is an important measure to improve its competitiveness. The main ways are: 1. Using high-quality materials. On the premise of ensuring the use function, reduce the unit consumption of raw materials; Improve the production technology level of plastic packaging materials and reduce production costs

in the application of high-quality new materials, LLDPE with high strength is used to replace LDPE to produce plastic packaging film. It once caused a great change in the plastic industry. It is expected that in the near future, there will be an upsurge of using metallocene catalyst to produce new polyethylene and polypropylene to replace traditional polyethylene and polypropylene to produce plastic packaging materials, which will bring economic benefits to plastic product manufacturers and application units

in terms of improving the production technology of plastic packaging materials and reducing production costs, the development and application have laid a solid foundation for the production of large-scale production devices. The large-scale production devices of plastic products have created ten favorable conditions for reducing product energy consumption or labor consumption. Therefore, the large-scale production devices of plastic films and sheets have become a very obvious trend. In recent years, China has successively established some 10000 ton BOPP production lines, and it is estimated that the trend of large-scale production units will be further expanded

3, adapt to the requirements of environmental protection

the wide application of plastic packaging materials has played a positive role in promoting industrial and agricultural production and meeting people's living needs. However, in the past, due to people's weak environmental awareness, discarded plastic packaging was thrown around, and a large number of vegetable cloths in nature, which has always been considered as a major advantage of plastic. The good stability has become a major obstacle to the rapid decomposition of plastic and its return to nature. A large number of plastic packaging materials are stored in nature, seriously affecting the ecological balance and causing great harm to the human living environment, which has attracted extensive attention from all countries, Industrial developed countries have put forward the so-called "three R-D" proposition to adapt to environmental protection, which is worthy of our reference in the future development of plastic packaging materials

"three Rs", namely:

1 Reduce the unit consumption of plastic packaging materials to reduce the amount of waste plastic packaging materials and reduce the pollution sources that may enter the nature. For example, the lightweight of plastic bottles, the thin thickness of plastic films, and the change of bottles to bags, of course, the reduction of unit consumption is carried out without reducing the use function of packaging

2. Pay attention to the reuse of plastic packaging materials, and recycling plastic bottles for multiple filling has become one of the hot spots of development and research. For example, Coca Cola has successfully developed and started to use pen bottles for multiple filling in Uruguay

3. Recycling of plastic packaging materials, including physical disposal, chemical degradation of waste plastic packaging materials to produce monomers or other chemical products; Or recycle energy through incineration to achieve the purpose of turning waste into treasure

"one D" refers to the development of degradable plastics often mentioned by people. Under certain conditions, such plastics can degrade quickly and return to nature, and can still maintain good physical and mechanical properties and chemical stability in use, playing a good protective role for commodities. From the perspective of degradation mechanism, there are biodegradable plastics and photodegradable biodegradable plastics. In terms of manufacturing methods, there are some new polymer compounds that are completely processed by biological products, some are completely synthesized by artificial methods, and some are based on existing plastics,

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