Acid rain-resistant antifouling aqueous nanometer polyurethane exterior wall finish

Abstract

The invention discloses an acid rain-resistant antifouling aqueous nanometer polyurethane exterior wall finish. The finish is obtained by mixing a primary finish, a curing agent and water according to a weight ratio of 10:1:1, wherein the primary comprises water, a dispersant, a wetting agent, a defoamer, propylene glycol, rutile titanium dioxide, a nanomaterial with the particle size of equal to or less than 20nm, a chemical inert filler, an antiseptic, a mildew inhibitor, a pH conditioning agent, a film forming assistant, an aqueous polyurethane resin containing -OH, and a thickening agent; and the curing agent comprises polyisocyanate containing -NCO, and PMA (polymethyl acrylate). The exterior wall finish of the invention has the advantages of acid rain resistance and good antifouling performance.

Description

technical field [0001] The invention relates to a water-based polyurethane exterior wall paint. Background technique [0002] The term "acid rain" was first proposed by the British chemist Smith Ding in 1872. He first proposed the term "acid rain" in his book "Air and Rain: The Beginning of Chemical Climatology". Atmospheric precipitation such as rain, freezing rain, snow, hail, and dew with a pH value between 4.3 and 5.6 is usually called acid rain. It has been confirmed that sulfur dioxide and nitrogen dioxide in the atmosphere are the main substances that form acid rain. Sulfuric acid accounts for 60%, nitric acid accounts for 32%, hydrochloric acid accounts for 6%, and the rest is carbonic acid and a small amount of organic acids. Sulfur dioxide and nitrogen dioxide in the atmosphere mainly come from the combustion of coal and oil, and they form acids dissolved in rainwater under the action of oxidants in the air. According to statistics, about 100 million tons of sul...

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Problems solved by technology

For example, the surface of the paint corroded by acid rain will be powdered, peeled off, foamed and yellowed, which greatly reduces the decoration requirements of buildings and affects the durability of the paint.

[0006] The reason for the pollution of exterior wall paint is that the wall surface is uneven, and the dust in the air entrained by rainwater falls to the surface of the paint film. There are gaps on the surface of the paint film, and small pollutants invade into the coating with the rainwater. It will stay in the paint film and form permanent pollution; in addition, the glass transition temperature of the base material used in exterior wall paint is low, and it is easy to become soft and sticky after being heated, or the coating is softened due to rainwater immersion, and the softened paint The film is more likely to absorb pollutants in the air, and pollution greatly reduces the decorativeness of the paint film

[0007] The current water-based architectural coatings are mainly based on styrene-acrylic emulsion and pure acrylic emulsion. The acid resistance of styrene-acrylic emulsion and pure acrylic emulsion is not good, so that the acid resistance of the finished coating is not good.

In addition, ordinary solvent-based polyurethane coatings use a large number of weakly alkaline pigments and fillers, such as calcium carbonate, aluminum silicate, etc., which will react chemically when encountering acid rain in nature. Long-term acid rain corrosion, the paint film is prone to discoloration, reduced adhesion, blistering, peeling and other disadvantages; at the same time, because the paint contains toxic solvents, it seriously pollutes the environment

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