How to improve the development of polyester film i

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How to improve the development of polyester film in China's food packaging after China's entry into WTO (Part 1)

in recent years, China has absorbed foreign experience in food packaging because of China's entry into WTO. Instead of simply pursuing the appearance of food packaging, it has begun to pay attention to the essence of packaging, focusing on the preservation of food, the pollution of packaging, and the improvement of shelf life, This trend can be shown by the development of plastic composite printing industry and high-performance BOPET film in recent years

first, the development of plastic composite printing industry is the basis for improving the quality of food packaging:

the development of China's economy has promoted the rapid development of plastic composite color printing industry. According to the reports of the national plastic flexible packaging conference and relevant magazines, the level of high-speed multi-color gravure printing machines designed and manufactured by China in the 1990s has been close to the international level, with good sales, with annual sales of more than 100 sets, Every year, more than 40 sets of plastic color printing machines are imported, and each one needs more than 500 tons of plastic film every year, so the output of various films needs to be increased by at least 60000 tons every year. With the further development of China's economy, the further improvement of people's living standards and the development of Northwest China will provide a good opportunity for the development of plastic packaging film industry. After joining the WTO, the company will keep up with the world level in food packaging. As a super large construction profile enterprise in Southwest China, the company will also increase the demand for BOPET film. The consumption of BOPET film in the Americas exceeded 380000 tons in 2000, and it is expected to increase at an annual growth rate of 3%. The average annual growth rate of BOPET film in the world is 4 ~ 6%. Although the application of BOPET film in audio and video tapes has declined, the growth in packaging and other industries has exceeded the average growth rate

Second, the excellent performance of polyester film meets the improvement of packaging quality

after SARS, consumers pay more attention to the hygienic requirements of food packaging, especially the requirements for the storage period of food, the fresh-keeping requirements of food, and the antibacterial requirements of packaging materials. Plastic is used to finance the core technology research and industrialization project construction of the new material industry. In order to meet the practical requirements of consumers, packaging manufacturers have changed from paying attention to beautiful appearance to the design of practical functional packaging, which has restored the real role and significance of food packaging. In this form, the demand for BOPET film with excellent performance has been increasing in recent years, and the quality of food packaging has also been improved. As a result, manufacturers who pursue the appearance excessively, increase the printing cost pointlessly, reduce the cost of packaging bags, participate in market competition, and reduce the performance standards in the selection of materials have lost the trust of consumers. We can clearly see from the following comparison

1. We compare the oxygen permeability between BOPP film and BOPET film, which are the most used in the market. Because oxygen permeability is an important property of food packaging, if the packaging bag is heat sealed well, the storage period of food determines the oxygen permeability of materials, especially for the selection of materials for vacuum packaging and deaeration packaging

according to the above data, the storage period of BOPP film packaged food is shorter than that of BOPET film packaged food. Fmax is an integral multiple of △ F, especially at room temperature, the shelf life of BOPET film packaged food in supermarkets is more than twice that of BOPP film. However, the reality is that most of the food packaged in BOPP is because the food packaging manufacturers ignore the packaging quality, which makes a large number of food beyond the storage period into the stall market and the processed goods market, endangering people's health

2 ﹐ comparison of vapor transmission rate of organic solvents

most organic solvents are harmful to human health, so consumers pay more attention to the protection of health with the improvement of living standards. However, today's composite printing in China is inseparable from organic solvents, especially in China, where there are many dry-type composites. How to choose barrier materials with low transmission rate of organic solvents is a manifestation of food packaging manufacturers' responsibility for people's health, In the United States, Japan and Europe, there are strict requirements for the transmission of organic solvents. After China's entry into WTO, it has attracted the attention of the composite printing industry. In recent years, the selection of packaging materials focuses on the selection of material properties, which also promotes the development of high-end packaging material BOPET film

after aluminizing, BOPET film shows its advantages. It not only further improves the resistance to oxygen, but also makes its humidity resistance better than BOPP. The humidity permeability of BOPET after aluminizing decreases from 40 ~ 45 to 0.3 ~ 0.6, while that of BOPP after aluminizing decreases from 5 ~ 7 to 0.8 ~ 1.2 (g/mm2.24h.40 ℃ - aluminum layer thickness 60 ~ 70mm)

3. The extensive application of BOPET film in packaging improves the strength of packaging bags, reduces the packaging materials per unit weight, and is conducive to reducing environmental pollution. At the same time, it improves the temperature application range of packaging materials, from the packaging of frozen food to the packaging of high-temperature cooked food

4 ﹐ high resistivity BOPET film vacuum coated silicon oxide transparent film 11 The application and development of the revolution measurement system will also drive the development of transparent packaging, practical application, recycling and environmental protection in China's food packaging industry

BOPET film coated with silicon oxide in vacuum, also known as soft glass, has the same effect as glass bottle packaging in terms of aroma preservation. After long-term storage or high-temperature treatment, it will not produce peculiar smell

its barrier performance is the same as that of aluminum plating. Its advantage is that the transparency of silicon plating is basically the same as that of the original film, so the packaged food can be seen clearly from the outside of the packaging bag, which increases the credibility and desire of consumers

in addition, due to the temperature resistance of BOPET film (it can be used for a long time at 130 ℃), the silicon plated film can be used for the packaging of microwave food. With the acceleration of people's daily pace of work and life, the lifestyle will also change, and microwave food will be welcomed by the majority of consumers

BOPET film is the most suitable material for vacuum silicon oxide plating. Silicon oxide evaporated film is to coat the glass film on the polyester film through evaporation, that is to say, the increase of impermeability is caused by the glass layer. Therefore, in order to maintain the barrier property in the process of evaporation and use after plating, the condition that the glass layer is not damaged must be maintained

the damage of the glass layer is caused by the thermal deformation of the base film during the evaporation process. The high temperature during the evaporation will cause thermal deformation to the materials that are not temperature resistant, which will produce internal stress and crack after cooling, affecting the barrier performance of the film

in the use process after plating, the required evaporating base film has a good straightness. In this way, the film is not easy to fold naturally, causing damage to the glass layer and affecting the decline of barrier performance

this material can be recycled, and silicon oxide has no impact on the properties of plastics in the recycled material, so it is also called environmental protection material

(to be continued)

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