Aqueous polyurethane coating with increased limiting film thickness and preparation method of aqueous polyurethane coating

Abstract

The invention discloses an aqueous polyurethane coating with an increased limiting film thickness and a preparation method of the aqueous polyurethane coating. The aqueous polyurethane coating comprises a composition A and a composition B, wherein the composition A comprises the following components in parts by weight: 35-42 parts of water based hydroxy acrylic acid a, 15-18 parts of water based hydroxy acrylic acid b, 25-30 parts of a filler, 1-3 parts of additives, 4-6 parts of a film-forming additive c and 7-10 parts of water; the composition B comprises the following components in parts by weight: 8-10 parts of water, 80-90 parts of isocyanate and 3-5 parts a film-forming additive d. The preparation method comprises the following steps: uniformly mixing and stirring water and part of the additives; adding the filler; carrying out dispersion in a high-speed state till the preset fineness is reached; then, reducing the dispersion speed, and uniformly stirring water based hydroxy acrylic acid a, water based hydroxy acrylic acid b and part of the additives to obtain the composition A; uniformly mixing and stirring water, isocyanate and the film-forming additive d to obtain the composition B. The aqueous polyurethane coating provided by the invention is extremely low in VOC, high in physical and mechanical performance, high in limiting film thickness, and suitable for the application scenario of environmental-friendly high decorative finishing coating.

Description

[technical field] [0001] The invention belongs to the technical field of chemical materials, and in particular relates to a water-based polyurethane coating with improved limit film thickness and a preparation method thereof. [Background technique] [0002] Two-component polyurethane coatings are produced by the reaction of polyisocyanates and polyols, and the coating film contains a considerable amount of urethane bonds. Polyurethane coatings contain not only urethane bonds, but also other functional groups, such as urea bonds, ester bonds, ether bonds, allophanate bonds, and acylurea bonds. As a result, polyurethane coatings not only have good mechanical properties, such as good hardness, flexibility, wear resistance and impact resistance; but also have excellent chemical resistance properties, such as good water resistance, acid and alkali resistance, Moisture and heat resistance; in addition, polyurethane has good weather resistance and can be used as a decorative topco...

AI Technical Summary

Problems solved by technology

However, with the gradual enhancement of environmental protection awareness and the introduction of VOC consumption tax, the development of water-based polyurethane is imminent. Therefore, increasing the limit film thickness of water-based polyurethane coatings (the highest film thickness without prickly heat) has become the technical key to the development of water-based polyurethane coatings. However, most waterborne polyurethane coatings have not yet reached the limit film thickness requirements of polyurethane coatings for construction machinery under the existing process conditions of construction machinery.

[0004] There are many examples of the invention of waterborne polyurethane coatings and their modified waterborne polyurethane coatings, but most of them focus on the water resistance or hardness after film formation, and there is no report on improving the non-foaming film thickness of waterborne polyurethane during use.

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