Polyvinyl alcohol (PVA) is a water-soluble polymer made of vinyl acetate through polymerization and alcoholysis, and its appearance is white powder, flocculent or flake solid. Its molecules are rich in hydroxyl groups and can interact with a variety of inorganic and organic materials. With its excellent film-forming, adhesive, environmental protection and cost advantages, it is widely used in the field of architectural coatings. The dosage accounts for more than 40% of the total amount of architectural adhesives. It is the core basic raw material and functional additive of the industry. With the upgrading of architectural coatings to environmental protection, functionalization and high quality, the application form and technology of PVA are continuously optimized, and continue to provide support for industry innovation.
The core characteristics of PVA are highly compatible with the needs of architectural coatings, which is the key to its wide application: first, water solubility and environmental protection are outstanding, soluble in warm water, no organic solvent is required, and it is suitable for indoor coating needs; second, adhesion and film formation are excellent, hydroxyl groups can form strong hydrogen bonds with wall base and pigment fillers, improve adhesion, film formation is flexible and smooth, and decoration is good; third, emulsification stability and compatibility are good, which can be synergistically optimized with bentonite, light calcium powder, etc., and the cost is low and the raw materials are sufficient. It should be noted that pure PVA coatings have poor water resistance, and their water resistance and scrub resistance can be significantly improved by modification or compounding.
Construction Chemicals - Polyvinyl Alcohol Products
Interior wall paint is the most widely used field of PVA, our country's architectural paint industry started with PVA as the main raw material, as a binder and film-forming agent, can be firmly bonded to the wall base, wrapping pigment filler to form a flat coating, with non-toxic, convenient construction, fast drying and other advantages, suitable for all kinds of building interior wall decoration.
In order to optimize the scrub resistance, PVA is often combined with bentonite in the industry to improve the stability of the coating through cross-linking reaction. For example, the formula with 3.0-3% PVA and 7.0-8% bentonite can increase the scrub resistance of the coating to more than 500-1000 times, meeting the needs of modern interior walls.
Pure PVA film has poor water resistance and weather resistance. It is easy to powder and crack after long-term outdoor exposure, so it is less used in pure exterior wall coatings. After compounding and modifying with acrylate and silica sol, its water resistance, weather resistance and anti-aging properties are significantly improved, and it can be used in exterior wall coatings. Modified PVA exterior wall coatings have both environmental protection and weather resistance, strong adhesion and good air permeability, can avoid coating bulge cracking, and are suitable for exterior wall decoration of civil buildings and industrial plants; at the same time, they can be used as thickeners and stabilizers to optimize coating construction and storage performance.
In functional coatings, PVA is a key additive to improve performance: in fireproof coatings, as a film-forming agent and binder, it cooperates with fireproof fillers such as aluminum hydroxide and expanded graphite to form a carbon layer at high temperature to block the spread of fire and improve the fireproof effect; in waterproof coatings, it is compounded with polyurethane and bentonite to improve the bonding force and impermeability, and can be used for the preparation of raw soil building protection and water-based waterproof coatings; in anti-mildew coatings, it is used as a carrier to load anti-mildew agents such as isothiazolinone to block the growth of mold after film formation and adapt to humid environments.
PVA can also be used as a thickener, dispersant, and film-forming aid to adjust the viscosity of coatings, promote pigment dispersion, reduce film-forming temperature, and optimize construction and storage performance. In addition, it can be used for the preparation of primer coatings to enhance the adhesion of topcoats and reduce the amount used; in the shotting process, it is mixed with cement and sand to improve the adhesion of subsequent coatings.
