Alkyd and preparation method

Abstract

The invention relates to alkyd which as low cost and good performance and especially can be used as baked enamel and PU (Polyurethane) paint and a preparation method thereof. The invention is characterized in that cheap castor oil fatty acid and water pool material (crude terephthalic acid) are adopted for carrying out catalytic esterification in the presence of hypophosphorous acid used as a catalyst. Compared with traditional soya oil fatty acid and phthalic anhydride type alkyd, the alkyd has the greatly reduced preparation cost of the resin with about 100yuan reduced per ton; in addition, the prepared resin has high impact strength, good glossiness, high adhesion and good color of final paint films; moreover, the obtained resin is short oil-length castor oil alkyd and especially can be used as the alkyd for making the baked enamel, which overcomes the defect that the traditional alkyd prepared by the prior art can not be used as the baked enamel as the low-cost water pool material is used; the one-step process also solves the technical problems that resin prepared by the traditional water pool material one-step process is not clear and has deeper color and the like; and furthermore, the esterification temperature is lower than that of the prior art for preparing the alkyd.

Description

technical field [0001] The invention relates to an improved alkyd resin and its preparation method, in particular to a low-cost, non-reducing performance, multi-purpose (usable in the fields of common baking varnish, coil steel baking varnish and PU paint) and its preparation method. Background technique [0002] Alkyd resin is a widely used synthetic resin for coatings, which can be used as primers and topcoats. It can also be used with other resins such as amino resins and polyurethane resins to prepare baking varnishes or two-component varnishes. Traditional alkyd resins include soy-oleic acid and phthalic anhydride-type alkyd resins, and most of the raw materials used in their production come from petroleum. Due to the impact of oil prices, the raw material prices of alkyd resins have risen greatly, and the cost has increased a lot. For this reason, it has become an important aspect for people to improve alkyd resin to explore the use of lower-priced alternative raw ma...

AI Technical Summary

Problems solved by technology

[0003] In China, terephthalic acid, pool material (crude terephthalic acid), and ground material (crude terephthalic acid) are used instead of phthalic anhydride to prepare alkyd resins. The cost of resin products has been reduced, but there are still many shortcomings such as: For example, the high-temperature esterification cycle is long, the resin is dark in color, the resin is opaque, and the production process control is complicated, etc., which cause the actual application of alkyd resin produced by this method to be greatly restricted.

[0004] The applicant has also tried to use crude terephthalic acid instead of phthalic anhydride to prepare air-drying alkyd resin by one-step high-temperature esterification. Although it has been successful, there are still some shortcomings: for example, one-step high-temperature esterification, high reaction temperature, It needs to be reacted at 280-290°C, and the production cycle is long, about 30 hours or more. The consumption is high, which wastes energy, and the prepared resin is dark in color, opaque in appearance, and its use is limited. It is difficult to make varnish and light color. paint

However, the production cycle is long (about 22-24 hours), the color of the resin is deep (above No. 12), and the obtained alkyd resin is an air-drying long-oil alkyd resin, which can only be used for self-drying paint, not for baking paint Not enough

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