Copolyester and preparation method thereof

Abstract

The preparation method comprises the following steps: carrying out esterification reaction on a binary monomer A and a binary monomer B serving as raw materials to obtain an esterification product, and adding a polybasic monomer C into the esterification product or simultaneously adding the polybasic monomer C and a polybasic monomer D for polycondensation reaction to obtain copolyester; wherein the acid value of the copolyester is 30 to 70 mg KOH / g; dissolving the prepared copolyester in water under the conditions that the temperature is 65-90 DEG C and ammonia water and a cosolvent are added; wherein the cosolvent is more than one of isopropanol, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, propylene glycol monobutyl ether, propylene glycol methyl ether acetic ether,dimethylethanolamine and propylene glycol methyl ether. The copolyester prepared by the method disclosed by the invention can be dissolved in water under specific conditions to prepare the water-soluble copolyester coating, does not use an organic solvent, and has the advantages of environmental protection, no pollution, no harm to human bodies and the like; meanwhile, various polar groups are introduced, and hydroxyl and carboxyl can react with an isocyanate curing agent to form cross-linked network structure resin.

Description

technical field [0001] The invention belongs to the technical field of copolyester and relates to a copolyester and a preparation method thereof. Background technique [0002] In order to improve the surface properties of articles, physical or chemical methods are usually used to modify the surface. Among them, uniform coating of a layer of polyester coating on the surface is the most commonly used measure, such as furniture, steel surface paint, and film surface. coating etc. There are two types of coatings: solvent-based and water-based. Because solvent-based coatings have a greater impact on the environment, water-based coatings are the future development trend. [0003] The paint on the surface of furniture and steel is commonly used as unsaturated polyester paint, which is commonly known as "piano paint". paint. Polyester paint is composed of three components: main paint, diluent, and curing agent. The main agent is a styrene solution of unsaturated polyester, and th...

AI Technical Summary

Problems solved by technology

However, most of the solvents and thinners in polyester paint are highly toxic benzene substances

[0004] The copolyesters of the prior art need to use organic solvents when preparing coatings, the pollution in the production process is relatively large, the use has a pungent smell and is harmful to the human body; and the copolyesters produced by the prior art have polar functional groups Less, generally ≤5mg KOH / g, poor adhesion

In addition, in the prior art, salt copolymerization is generally used to improve the solubility of copolyester and water, but this kind of material is very hydrophilic after being made into a finished product, and it will dissolve or swell in water, and water will destroy the performance of the material