New recycling technology for used polyester bottles (top)

Abstract: This paper briefly describes the main recycling technology of waste PET bottles, introduces the practice of industrial recycling technologies for several new waste PET bottles, and discusses the prospects of the recycling of used PET bottles.

Keywords :waste polyester bottle; recycling technology

In the past 20 years, with the rapid development of China's economy, people's packaging concepts have undergone tremendous changes, and the packaging materials used in the products have been continuously refurbished. Among them, plastic packaging materials have developed rapidly and gradually occupy a very important position in the packaging field. The development of polyester beverage bottles in plastic packaging materials is rapidly gaining popularity.

The main component of polyester bottle is polyethylene terephthalate (PET, or polyester for short), which is a new type of synthetic plastic material successfully developed by British ICI, because the polyester resin has excellent mechanical properties and Wear resistance, good creep resistance and rigidity, low water absorption, high dimensional stability, good thermal stability, excellent electrical insulation and excellent chemical resistance, etc. . Polyester resin was first used to make fibers, and later DuPont researched and developed bottle polyester resins and started the application of polyester bottles. Polyester bottle is odorless, odorless, non-toxic, light weight, high strength, good airtightness, good transparency, etc. Among them, the good transparency of PET bottle makes the product displayable, which is unmatched by other packaging materials. of. Therefore, PET bottles have been widely developed in food packaging, especially for carbonated beverages, mineral water, edible oil, and other product packaging are almost all PET bottles.

China's polyester bottle resin has developed rapidly and the amount of polyester bottles has increased dramatically. In 1995, the use of bottle-grade polyester resin was 100,000 tons, of which domestically produced 60,000 tons. In 1999, the consumption of bottle-grade polyester resin was 400,000 tons. In 2000, the dosage reached 520,000 tons and was fully domesticated. As the demand for bottle-grade polyester resins is still growing, and people's expectations for the future use of bottle-grade polyester are good, the large companies that produce polyester all over the world have expanded the production capacity of bottle-grade polyester resins. In Asia, Formosa Plastics Group will increase the production capacity of 150,000 tons of bottle grade polyester in the United States and Taiwan, and Taiwan Far East Textile will expand production on both sides of the Taiwan Strait. Its annual production capacity will reach 400,000 tons of bottle grade polyester; Xinguang Synthetic Fiber is planning to increase its production capacity in Taiwan and Thailand to 500,000 tons per year; this will enable the global bottle grade polyester resin production capacity to grow rapidly.

China's bottle grade polyester resin dosage, most experts believe that in the next five years will be 20% to 30% annual growth rate, by 2005 will be 143 million tons bottle grade. Such a huge amount of polyester resin is put into the market, and consumption will inevitably raise the issue of recycling PET bottles. Since the food industry does not allow the use of physically recycled disposable polyester bottles or polyester films, almost all polyester bottles and polyester films are disposable packaging materials. Waste PET bottles can not be spontaneously degraded when they enter the environment, which will cause serious environmental pollution and waste of resources. Therefore, polyester packaging materials such as used PET bottles must be recycled.

At present, the recycling volume of waste polyester bottles in the world is 600,000 tons per year, and the recovery rate is 18%, while the domestic recovery rate is between 6% and 10%. Therefore, it is necessary to increase the recycling efforts and increase the recycling rate of waste PET bottles. However, the recycling of waste PET bottles is very difficult, and there are many factors that affect them. Therefore, the recovery rate of polyester bottles is very low in the world.

The recycling of used PET bottles should pay attention to the following aspects: (1) Raise awareness of recycling in the society as a whole, establish a social recycling network where most of the population participate, and take effective measures to stimulate and encourage recycling of used PET bottles, such as the establishment of Deposit system, reward system, strict environmental regulations for polyester bottles, etc.; (2) Adjustment policies to make the recycling industry and its products economical, so that renewable products can be profitable, such as implementing tax relief policies; (3) increase recycling Technical research, expanding the application areas of polyester packaging such as recycled polyester bottles, including automatic identification, classification, and whether the quality of recycled products can be guaranteed, and other technologies must be supported; development of recycling technologies for PET bottles and other polyester packagings Relative economic efficiency will be the key to increasing the recovery rate of used PET bottles.

Waste PET bottle recycling technology is divided into physical recycling technology and chemical recycling technology.

Physical recovery technologies include:

(1) Direct recovery, cleaning and reuse. If the used polyester bottles are recycled and reused like glass bottles, the polyester bottles are required to be heat-resistant and resistant to 2% to 3% sodium hydroxide solution to facilitate cleaning. The current PET bottles are disposable and cannot be reused. In 1989, the Dutch market took the lead in the introduction of reusable PET bottles and specialized equipment designed for reused PET bottles. The desire for this new technology for reusing PET bottles has gradually entered the market.

(2) After crushing, re-produce the package. After the old PET bottles are collected, sorted, washed, and crushed, they can be reused in two different situations. First, the used PET bottles are crushed and granulated and used as products, and partially added to other plastic products to reduce the plastic content. The purpose of the cost; Second, the waste polyester bottles are crushed and granulated and then re-inflated and stretched to form a new packaging container. This packaging container can only be used for non-food packaging. The reason is that the recycled polyester is blown under high temperature and stretched, some of the polyester molecules decompose to generate acetaldehyde, and acetaldehyde is poisonous, so that excessive acetaldehyde is left in the recycled polyester packaging container, thus recovering the packaging of polyester bottles and the like Economic efficiency will be greatly reduced. Therefore, only the development of economic chemical recovery technology can effectively promote the recycling of polyester resin.

Chemical recovery technologies include:

(1) Direct recovery of fiber production technology;

(2) Conversion technology to produce polyester resin raw materials;

(3) Direct recovery of various fine chemical products.