A kind of polyester resin for indoor low-temperature curing powder coating and preparation method thereof

Abstract

The invention relates to the field of powder coatings, and specifically discloses a polyester resin for indoor low-temperature curing powder coatings, which is prepared from the following raw materials in weight percentages: 45% to 55% of polybasic acids; 35% to 45% of polyhydric alcohols; 0.05%~0.1% of curing agent; 8%~15% of acidolysis agent; 0.05%~0.1% of esterification catalyst; 0.1%~0.3% of antioxidant; 1.0%~1.5% of curing accelerator. The present invention adopts the synthesis design idea of ​​semi-crystal, adopts symmetrical polybasic acid and polyhydric alcohol, and combines step-by-step feeding polycondensation process and vacuuming process to prepare semi-crystalline polyester resin, which well controls acid value and molecular weight, and makes The powder coating made of it has a low curing temperature, and has excellent storage stability, leveling and flexibility of the paint film, and also takes into account hardness, heat storage, salt spray resistance and other properties.

Description

technical field [0001] The invention relates to the field of powder coatings, in particular to a polyester resin for indoor low-temperature curing powder coatings and a preparation method thereof. Background technique [0002] With its advantages of economy, environmental protection, high efficiency and excellent performance, powder coatings are gradually replacing organic solvent-based coatings, becoming an important development direction in the coatings industry, and have maintained a relatively fast growth rate. Powder coating metal building materials are also widely used in all aspects of buildings due to their excellent durability, decoration and processing formability. Although the advantages of powder coatings are outstanding, compared with liquid coatings, thermosetting powder coatings generally have higher leveling and curing temperatures (180°C to 200°C) and longer curing times (10 to 30min). In this way, the powder coating can only be used on heat-resistant metal...

AI Technical Summary

Problems solved by technology

First of all, the curing process of powder coatings is a low-temperature latent curing system. Assuming that the chemical reactivity of the system is relatively high at lower temperatures, it will inevitably affect the stability of powder coatings in melt extrusion and storage; secondly, polycool resins for powder coatings Both the curing agent and the curing agent are solid, and both have a high softening point. At low temperature, their melt viscosity is too high. Exterior

If resin and curing agent with low softening point are used, although the melt viscosity at the curing temperature can be reduced, the storage stability of the powder coating will be deteriorated, and it is usually stored in low temperature refrigeration, which brings a lot of inconvenience to the use. Therefore, seeking a resin and curing agent with low melt viscosity and good leveling performance at low temperature and good storage stability is the key to the successful preparation of low temperature curing powder coatings.

[0004] At present, the polyester resins used for low-temperature curing powder coatings on the market have great defects, such as poor adhesion, poor flexibility, orange peel on the paint surface, poor storage stability, and low hardness.

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