Amide-modified polyester resin for powder coating and powder coating

Abstract

The invention discloses amide-modified polyester resin for a powder coating and the powder coating, and belongs to the technical field of coatings; the amide modified polyester resin for the powder coating comprises 35%-40% of polyol, 50%-53% of polybasic acid, 0.6%-3.1% of polybasic anhydride, 0.4%-2% of polyamine, 0.04%-1% of an esterification catalyst, 8%-15% of an acidolysis agent, 0.2%-1% of an antioxidant and 0.03%-0.05% of a curing accelerator; amide bonds are connected into polyester resin through polymerization reaction, and nitrogen atoms in the amide bonds have a pair of lone pair electrons, so that connection of the connected amide bonds plays a role of an electricity increasing agent; and meanwhile, compared with the prior art that amine compounds in a free state are directly added into a formula to serve as an electricity increasing agent, the amido bonds are grafted into the polyester resin through polymerization, the bond energy of a covalent bond formed in the polymerization grafting process is large, the covalent bond is not prone to breakage after being heated, and thus the introduction of the amido bonds cannot influence the glass transition temperature of the polyester resin, and the thermal stability of the polyester resin is improved.

Description

【Technical field】 [0001] The invention relates to the technical field of coatings, in particular to amide-modified polyester resins for powder coatings and powder coatings. 【Background technique】 [0002] The charging performance of powder coatings will affect the powder coating rate of powder coatings, reduce the electrostatic shielding effect, and improve the powder coating on corners. The existing method to improve powder charging performance is to add a charge enhancer to polyester resin or powder coating formula (Generally amine organic compounds such as triisooctylamine, etc.), this type of power enhancer is generally in a liquid state at room temperature, after adding, it will reduce the glass transition temperature of polyester or powder coatings, and it will also be cured after powder coatings are baked and solidified. Occasionally produce smog, which is not conducive to environmental protection. [0003] A preparation method of a semi-aromatic polyamide polyester ...

AI Technical Summary

Problems solved by technology

[0006] Curing agent is an important part of powder coatings, it will have an important impact on the production, storage and application of coatings, such as extrusion temperature, curing time, curing temperature, leveling, impact resistance and hardness, storage stability, Weather resistance and chemical resistance, etc., the weather-resistant curing agent cured with carboxyl-terminated polyester resin in existing powder coatings mainly includes triglycidyl isocyanurate (TGIC) and β-hydroxyalkylamide, and the coating film cured by TGIC It performs well in all aspects, but it is sensitizing and potentially carcinogenic to the human body, and β-hydroxyalkylamide is relatively non-toxic and harmless, and is favored by people. Polyester resin end-capping acids generally include isophthalic acid, 1,4-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, etc., or a mixture of one or more of them, when the obtained polyester resin reacts with β-hydroxyalkylamide curing agent at 180-200°C Because the hydroxyl group in the β-hydroxyalkylamide curing agent is affected by the amide structure, the activity becomes very high, and the functionality of this type of curing agent is relatively large, resulting in a particularly fast reaction with the polyester resin, making the prepared The leveling effect of powder coating is poor, and the coating film is prone to pinholes

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