Polyester resin and preparation method and application thereof

Abstract

The invention discloses a polyester resin and a preparation method and application thereof. The polyester resin has an acid value of 30 to 80 mgKOH / g, a glass transition temperature of 40 to 80 DEG C,a melt viscosity of 1000 to 10000 mPa.s at 200 DEG C, a softening point of 80 to 123 DEG C, a reactivity of 100 -300 s at 180 DEG C and a number average molecular weight of 3000-7000; and the polyester resin is prepared from polyester waste, polyol, polybasic acid, and a blocking agent. The above-mentioned properties of the polyester resin have a wide range of variations, and thus have higher applicability; at the same time, the polyester resin is prepared from the polyester waste, so that the preparation conditions are mild, no by-products are formed during the preparation, and the pure polyester resin is completely prepared through one-step reaction; and powder coating prepared from the polyester resin has better surface appearance, excellent mechanical properties and adhesion, chemicalresistance, salt resistance and high boiling performance, and is suitable for various indoor coating fields.

Description

technical field [0001] The invention relates to the field of material recovery and reuse, in particular to a polyester resin and its preparation method and application. Background technique [0002] With the rapid development of polymer materials, polymer materials represented by polyester plastics have been widely used in various fields, especially in plastic bottles and engineering plastics. These materials will produce a large amount of gas after use. waste, and because polyester plastic has chemical stability, corrosion resistance, electrical insulation, and heat insulation, it is not easy to decompose naturally, and it will cause great damage to the environment if it is left in the environment for a long time, which is not conducive to sustainable development; at the same time , The cost of polymer materials using crude oil or natural gas as raw materials continues to increase, and the resources continue to decrease, making the recycling and reuse of polyester waste a n...

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Problems solved by technology

[0002] With the rapid development of polymer materials, polymer materials represented by polyester plastics have been widely used in various fields, especially in plastic bottles and engineering plastics. These materials will produce a large amount of gas after use. waste, and because polyester plastic has chemical stability, corrosion resistance, electrical insulation, and heat insulation, it is not easy to decompose naturally, and it will cause great damage to the environment if it is left in the environment for a long time, which is not conducive to sustainable development; at the same time , the cost of polymer materials using crude oil or natural gas as raw materials continues to increase, and the resources continue to decrease, making the recycling and reuse of polyester waste a new topic and an urgent problem to be solved

[0003] The recycling of polyester waste mainly focuses on the direction of polyester hot melt, polyurethane elastomer and water reducer, for example: CN101760163A, CN107163892A and CN101434821A have all reported the method of using polyester waste to prepare hot melt adhesive, and CN101851326A has reported A method for preparing polyurethane elastomers using PET waste. CN103274628A discloses a method for producing water reducers using waste PET plastics. However, there are relatively few studies on the use of polyester waste to degrade powder coatings. In the production of polyester resin, the types of raw materials are basically the same as those used in the production of polyester plastics. It is a direction worth studying to use polyester waste to degrade and prepare polyester resin for powder coatings. CN106065068A discloses the use of polyester waste to prepare powder Pure polyester for coatings; CN101177503A discloses the use of compound heating method to recycle waste polyester to prepare polyester for powder coatings, but the acid value, melt viscosity, glass transition temperature and other properties of the polyester resin prepared by polyester waste are currently The range of variation is narrow, and it is not suitable for wide application. At the same time, the above-mentioned method has high alcoholysis temperature, incomplete alcoholysis reaction, more by-products, or needs to use heating instruments such as infrared heating boxes and microwave ovens. On the one hand, it affects the polyester waste. The recycling rate, or its by-products cause new environmental pollution, and on the other hand, it is not conducive to actual operation, limiting its large-scale production

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