Glass bottles can be reused and are inconvenient to carry, but there is a phenomenon of unclear cross-contamination and repeated counterfeiting. People are afraid to rest assured.

Compared with glass, plastic bottles have a larger permeability coefficient of oxygen and carbon monoxide, which will lead to a chemical reaction between the packaged object and the packaged object, and the packaged object will also deteriorate in taste due to oxidation. The aging of the product also affects the appearance quality, is not beautiful and practical, and pollutes the environment.

With the continuous application of new materials and new technologies, there have been plastics represented by PC, PET, PEN, PET and PEN mixed materials, and other new plastics such as PETG. What are their pros and cons?

The advantages of PC are that it can withstand high temperatures above 120 °C and has high mechanical strength, but it is expensive and has poor gas barrier properties, and has gradually withdrawn from the field of beer packaging. There are now reports of improved PCs being brought back to the market.

PEN has good heat resistance and gas barrier properties, can resist ultraviolet rays, can also withstand pasteurization and high temperature immersion temperature, its service life can exceed 6 months, light weight, but high cost, which limits the popularization and application scope of PEN .

So PET appeared, but because it is not resistant to high temperature, it is suitable for cold sterilization beer, because sterilization beer uses membrane filtration technology and does not undergo pasteurization or high temperature instantaneous sterilization. However, it can not block the infiltration of gas well, not only the content of carbon dioxide is low, but also it is easy to cyanide and deteriorate the beer, so its application is greatly limited. But PET is the earliest developed, largest and most widely used polyester product.

PET can easily obtain basically amorphous, highly transparent and easy-to-stretch PET products by rapid cooling, so when used as packaging materials, PET can be made into biaxially oriented packaging films and non-standard preforms. High-strength, high-transparency stretch blow-molded bottles can be obtained, and can also be directly extruded or blown into non-stretch hollow containers.

PET film has the properties of transparency, oil resistance, fragrance preservation, hygienic reliability and wide range of use temperature (both high temperature steaming and freezing packaging), especially for stretch plastic bottle molding, of which tens of milliliters to 2 liters are the most widely used. Small bottles, there are also large bottles with a capacity of 30 liters.

In beverage packaging, the most successful application is carbonated soft drinks (CSD), such as Coke, Sprite, etc. CSD bottles account for 1/3 of the total amount of PET bottles. In 1998 alone, PET bottles accounted for 57.4% of CSD packaging in China. As early as 1995, the application of condiments in Japan exceeded 30,000 tons, accounting for 13% of the total consumption of PET bottles. Data show that the sales volume of PET bottles in Japan in 2000 rose from 220 million to 250 million, and in the five years from 1995 to 2000, PET bottles rose from 15% to 36%.

Germany generally adopts PET bottle blow molding technology suitable for beverage and beer products, and the instantaneous output can reach 1200 bottles/mold. Moreover, it has good environmental protection and energy saving characteristics, and the production energy consumption is only 41% to 64% of that of glass bottles. If it is further recycled and reused, its energy consumption can be reduced by about 50%. If my country's beer production in 2000 exceeded 20 million tons as the base, about 25 billion to 30 billion beer bottles (including recycling) could be consumed. Even if it is partially replaced, by 2005, my country's PET bottle demand will reach 60 million. 10,000 to 650,000 tons, unlimited business opportunities.

Due to the poor heat resistance and gas barrier properties of PET, its application in hot canning and applications requiring high air tightness is limited.

In order to solve the problem of poor heat resistance, people have developed three types of practical heat-resistant polyester bottles through research; heat-setting new bottles can meet the requirements of filling at 85 °C; PET/PEN alloy bottles, PEN has high heat resistance, Bottles that meet the requirements of hot cans above 80 °C can be produced on ordinary injection stretch blowing equipment. If heat-setting treatment is performed, the hot filling temperature can reach above 90 °C; it can be made into multi-layer composites with heat-resistant polyarylate, etc. bottle to improve heat resistance.

For solving the problem of poor gas barrier properties, there are three main methods at present: one is multi-layer compounding, mainly PET, and PEN and other materials with good air tightness are added to make 3-layer or 5-layer bottles; the second is to use special treatment Methods, such as coating an epoxy barrier layer on the inner or outer layer of a PET bottle, or performing plasma treatment; the third is molding with other barrier resins, using PEN or a copolymer or blend of PEN and PET as raw materials, which not only improves the The yin property of the bottle improves the heat resistance of the bottle, and it can also be disinfected with alkali and reused, thereby reducing the cost, because the first two methods have problems such as poor transparency, difficult recycling and processing, complex process, and special equipment requirements. And although the air tightness is improved, the heat resistance is poor, and it can only be adapted to the occasion of aseptic filling.