Terminal carboxyl group polyester resin for weather-resistance high-gloss powder coating and preparation method thereof

Abstract

The invention discloses a terminal carboxyl group polyester resin for a weather-resistance high-gloss powder coating. The terminal carboxyl group polyester resin is obtained by carrying out melt polycondensation on the following components in percentage by weight: 25-45 percent of polyalcohol, 35-65 percent of aromatic polyacid, 0-3 percent of fatty polyacid, 0-1 percent of branching agent, 6-20 percent of acid-hydrolyzing agent and 0.01-0.15 percent of esterification catalyst. The invention also discloses a preparation method of the terminal carboxyl group polyester resin for the weather-resistance high-gloss powder coating. The polyester resin has proper glass-transition temperature, softening point, viscosity and storage stability; and the powder coating prepared by adopting the preparation method disclosed by the invention has 60-degree gloss more than 96 percent and favorable leveling performance and weather resistance.

Description

technical field [0001] The invention relates to a carboxyl-terminated polyester resin for weather-resistant high-gloss powder coatings, and also relates to a preparation method of the carboxyl-terminated polyester resin for weather-resistant high-gloss powder coatings. Background technique [0002] The improvement of powder coating technology is the comprehensive result of improving equipment and construction technology from raw materials in the coating industry. Its goal is to obtain coatings with performance equivalent to liquid coatings in all aspects, including pleasing appearance, lower curing temperature, and thinner coatings. , high outdoor durability, good construction, but also committed to environmental protection and cost-effective. Improving the appearance of powder coating film is always the goal that people pursue, and making high-leveling and high-gloss coating film has always been the focus of the powder coating industry. Powder coatings are generally compos...

AI Technical Summary

Problems solved by technology

In order to obtain high leveling, the viscosity of polyester resin, which is the key material of powder coating, is required to be low, and the viscosity is too low to affect the mechanical properties of the resin; on the other hand, in order to have qualified storage stability, the vitrification of polyester resin for powder coating The temperature must be above 50°C, and the weather-resistant polyester must even be above 60°C, but if the glass transition temperature is too high, the melt flow temperature of the corresponding resin will also increase accordingly, and the leveling will deteriorate

Few literatures and patents at home and abroad report carboxyl-terminated polyester resins for high-gloss powder coatings and their preparation methods. US Patent US 6555226 reports a kind of acid value of 35-55mgKOH / g, hydroxyl value of less than 10mgKOH / g, and viscosity of less than 1500mPa. s (200°C) high-gloss carboxyl-terminated polyester resin, mainly using neopentyl glycol, trimethylolpropane, 1,6-hexanediol, terephthalic acid, 1,4-cyclohexanedicarboxylic acid, Trimellitic anhydride, etc. are synthesized, and the 60° gloss of the powder coating is more than 96% after film formation and curing, and the highest can reach 98%. However, as analyzed above, the maximum glass transition temperature of the carboxyl-terminated polyester resin synthesized by this patent is only 55 ℃, affecting the storage stability of powder coatings made of it, limiting its application and promotion

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