A kind of thermosetting saturated carboxyl-terminated polyester resin and preparation method thereof

Abstract

The invention discloses a thermosetting saturated carboxyl-terminated polyester resin and a preparation method thereof. The raw materials include dibasic or polybasic acid monomers, dibasic or polyvalent alcohol monomers, catalysts, heat stabilizers and acidifiers, and the crystallinity can be as high as 47.85%, good crystallinity, it uses dibasic or polyalcohol, dibasic or polybasic acid as raw material, (1) rigid groups such as phenyl and cyclic compounds are introduced into the main chain, which hinders the rotation of single bonds and reduces the The flexibility of the main chain of the polyester resin molecule increases the Tg of the resin and improves the storage stability of the powder coating produced by it; (2) The monomer with a symmetrical structure improves the regularity of the molecular chain, makes the resin partially crystallize, and forms a crystalline structure It is beneficial to reduce the melt viscosity of the powder coating system configured with the resin and improve the reactivity of the resin and the curing agent. The polyester resin has undergone a fundamental change in the molecular structure, and the synthesized thermosetting saturated carboxyl-terminated polyester resin has low viscosity, high Tg properties.

Description

technical field [0001] The invention relates to the field of polymer polyester resin synthesis, in particular to a thermosetting saturated carboxyl-terminated polyester resin with a certain degree of crystallinity and a preparation method thereof. Background technique [0002] Thermosetting polyester powder coating has excellent weather resistance, corrosion resistance, electrical properties and mechanical properties, and has no VOC volatilization, simple process, easy automation and recyclable powder. It is a category with a large amount Environmentally friendly powder coating. At present, the powder coatings for industrialized production and large-scale application are all thermosetting resin systems. More than half of the production of thermosetting powder coatings in the world uses polyester resin as an important part of the base material. Due to its excellent comprehensive performance and relatively low cost, thermosetting polyester powder coatings are widely used in t...

AI Technical Summary

Problems solved by technology

At present, the carboxyl-terminated polyester resin commonly used in thermosetting powder compositions is synthesized by direct esterification with neopentyl glycol (NPG) and terephthalic acid (TPA) as the main monomers, and has an amorphous structure. The linear polycondensation product, its molecular main chain is composed of saturated single bonds, and the flexibility of the molecular chain is good, resulting in a low glass transition temperature (Tg), which easily leads to the agglomeration and stability decrease of the powder coating prepared by polyester resin. Therefore, the Tg of the resin must be increased

However, the practice of increasing the Tg of amorphous polyester resin by increasing the high molecular weight of the resin, moderate crosslinking and other means often increases the melt viscosity of the coating system while increasing the Tg of the resin, reduces the curing reactivity of the resin, and improves the coating performance. High curing temperature, even lead to orange peel phenomenon in the coating film, which is very unfavorable to the curing and film-forming process of powder coatings

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