The action mechanism and types of anti-mildew agents for coating are described(一）
Antimildew agent is a kind of polymer material additive that can inhibit mold growth and kill mold. It can make polymer materials free from fungus erosion and maintain good appearance and physical and mechanical properties. Coating film forming material is composed of various natural and synthetic polymer compounds, to withstand the destruction of oxygen, heat, light, chemical erosion and other environmental factors, but also be destroyed by a variety of organisms such as mold. Coating is contaminated by microorganisms, viscosity decline, pigment settlement, odor, gas, container expansion, pH drift and system damage phenomenon, known as corruption. In solvent - based coatings, the problem of corruption is not prominent. Mold erosion film, resulting in film color change, sticky, perforation, damage and peeling, loss of adhesion, affect the protective performance of film and material clean and appearance, reduce mechanical properties, shorten the service life, cause harm to environmental health.
The natural polymer materials used in coating contain casein, soybean protein, alginic acid, starch, natural gum, cellulose derivatives, fat and other substances that can be ingested by mold, and are vulnerable to mold damage. Most synthetic polymer materials have strong antibacterial activity, some varieties (such as polyurethane, polyacrylate, polyvinyl acetate, polyvinyl alcohol, pervinyl chloride, vinylidene chloride, etc.) due to its structure, bacterial resistance is poor, easy to be decomposed by mold. Additives used in coating (such as plasticizer, heat stabilizer, light stabilizer, organic filler, colorant, etc.), is not only the nutrient source of mold, many varieties or bacterial substances, adding these additives is often the main cause of coating and coating bacteria damage. The dust adsorbed on the surface of the film is also the nutrient source of mildew.
1. Action mechanism of coating mildew inhibitor
The mold of corrosion coating and coating film belongs to fungi, including Aspergillus Sassi, Aspergillus flavus, Aspergillus Niger, Aspergillus aspergillus aspergillus, Aspergillus auriculatus, Penicillium purpura, Penicillium extensium, Penicillium derangae, Penicillium paecilomyces, Trichoderma, cephalosporus, cladomyces spore, transcladomyces, Staphylosporus glucosporus, blastomyces spore, etc. Mold is a diverse group of microorganisms that can be found almost everywhere, in soil, water, plants and animals, or in the air. Moulds survive as parasites or saprophytes by absorbing nutrients from other objects, secreting a variety of enzymes that break down organic matter into easily digestible nutrients. As long as there is very little nutrition, under the suitable temperature (26 ~ 32℃) and humidity (> 85%), mold can grow and reproduce.
The killing effect of antimildew agent on mold is to enter the cell through the cell membrane of spores, hinder spore germination or kill spores. The toxic action of antimildew agent on mold includes the following ways: eliminate or inhibit the activity of various metabolic enzymes in mold cells; React with amino or sulfhydryl groups of enzyme proteins to inhibit or destroy their function; Inhibit the synthesis of RNA during spore germination, thus preventing spore germination; Accelerate the promotion of phosphoric acid oxidation - reduction system to destroy cell function; Destroy the energy release system in mold cells; Inhibition of electron transfer system and transaminase system.
