Comprehensively understand waterborne wood coatings using water-based paints

Any coating that uses water as a solvent or as a dispersion medium can be called a water-based paints(water-soluble coating).water-based paints is mainly used for wood coatings. water-based paints have advantages such as resource conservation, no pollution, good protection, and good corrosion resistance, but they contain a high amount of water. If not careful with temperature control during transportation, they can easily freeze and because of the water, they are prone to bacterial growth, so attention must be paid to preservation against mold and mildew. water-based paints have been widely applied in various fields.

        The three stages of development of water-based paints technology:

▶The first generation of water-based coatings uses acrylic as the main raw material, with advantages such as water resistance and good weather resistance. However, their overall performance is average, chemical resistance is low (e.g., poor resistance to alcohol and alkali), and physical indicators such as hardness and wear resistance are low. This is why many people consider water-based coatings to be poor.

▶The second generation of water-based coatings uses a composite of acrylic and waterborne polyurethane as the main raw material, inheriting the good weather resistance and ease of application of the first-generation acrylic products, while also improving the hardness of water-based coatings. However, chemical resistance remains low, and currently, only a few companies in China can produce them, making them mid-range products in the water-based coatings market.

▶The third generation of water-based coatings uses acrylic-modified waterborne polyurethane as the main raw material, significantly improving the overall performance of the second-generation water-based paint products on the basis of. The pencil hardness test can reach 2H or above, fully meeting daily needs. The wear resistance even exceeds that of oil-based paints, with clear advantages in terms of service life and color matching. More importantly, chemical stability is good, and resistance to alcohol and alkali is significantly enhanced compared to the previous two generations, making them better products in the water-based coatings market, with this technology being monopolized by a few manufacturers both domestically and internationally.

Although water-based coatings have advantages such as being environmentally friendly and having good film effects, single-component water-based coatings still have a gap in hardness and high-temperature resistance compared to two-component oil-based paints. For example, using them on dining tables and floors can easily reveal their shortcomings in performance. 

▶water-based coatings.

Fake two-component water-based coatings are constantly emerging in the market. Some small paint factories have started to promote two-component water-based coatings, which are actually improved products of ordinary paint. Although their hardness and other properties have been significantly improved, they still contain a large amount of toxic substances, going against the original intention of water-based coatings to be environmentally friendly, non-toxic, and protective of the environment and human health.

Water-based coatings include water-soluble, water-dilutable, and water-dispersible types.

▶ Water-soluble

Water-soluble coatings use water-soluble resins as the film-forming material, with polyvinyl alcohol and its various modified products as the main components, as well as water-soluble alkyd resins, water-soluble epoxy resins, and inorganic polymer water-based resins.

▶ Water-dilutable

Water-dilutable coatings refer to paints prepared with post-emulsified emulsions as the film-forming material. Solvent-based resins are dissolved in organic solvents, and then, with the help of emulsifiers and strong mechanical stirring, the resins are dispersed in water to form an emulsion, known as a post-emulsified emulsion. The resulting paint can be diluted with water during application.

▶ Water-dispersible

Water-dispersible mainly refers to coatings prepared with synthetic resin emulsions as the film-forming material. Emulsion refers to the dispersion of small particle clusters formed by the polymerization of unsaturated vinyl monomers at certain temperatures in the presence of emulsifiers under mechanical stirring, dispersed in water. Coatings prepared by adding a small amount of emulsion to water-soluble resins cannot be called latex paints. Strictly speaking, water-dilutable paints cannot be called latex paints either, but they are still commonly classified as latex paints.

Advantages:

▶ Using water as a solvent saves a significant amount of resources;

▶ Eliminates the risk of fires during construction;

▶ Reduces air pollution;

▶ Only uses a small amount of low-toxicity alcohol ether organic solvents, improving working conditions;

▶ General water-based coatings have organic solvents (as a percentage of the paint) between 15%, while cathodic electrophoretic coatings have dropped to less than 1.2%, significantly reducing pollution and saving resources;

▶ Water-based coatings can be directly applied on wet surfaces and in humid environments, have good adaptability to the surface of materials, and strong coating adhesion;

▶ Coating tools can be cleaned with water, reducing the consumption of cleaning solvents and effectively reducing harm to construction workers;

▶ Electrophoretic coatings are uniform and smooth, with good leveling properties;

▶ Cavities, welds, corners, and edges can all be coated with a certain thickness of the coating, providing good protection;

▶ Electrophoretic coatings have good corrosion resistance, and the salt spray resistance of thick film cathodic electrophoretic coatings can reach 1200 hours.

Disadvantages:

▶ Water-based coatings have high requirements for cleanliness during construction and on the surface of materials. Due to the high surface tension of water, dirt can easily cause pinholes in the coating;

▶ Water-based coatings have poor dispersion stability against strong mechanical forces. When the flow rate in the delivery pipeline changes rapidly, the dispersed particles are compressed into solid particles, causing the coating to have pits;

▶ Water-based coatings are corrosive to coating equipment, requiring anti-corrosion linings or stainless steel materials, which increases equipment costs. The corrosion of water-based coatings on delivery pipelines also causes the dispersion particles to precipitate, causing pits in the coating, requiring the use of stainless steel pipes;

▶ Baked water-based coatings have strict requirements for construction environment conditions (temperature, humidity), increasing the investment in temperature and humidity control equipment, and also increasing energy consumption;

▶ The latent heat of evaporation of water is large, and the energy consumption for baking is high. Cathodic electrophoretic coatings need to be baked at 180°C; while latex coatings take a very long time to fully dry;

▶ High boiling point organic co-solvents produce a lot of smoke during baking, which condenses and drips onto the coating surface, affecting the appearance;

▶ Water-based coatings have poor water resistance, causing problems with the stability of the coating and the coating solution, and poor water resistance of the coating. The medium of water-based coatings is generally slightly alkaline (pH 7.5 to pH 8.5), and the ester bonds in the resin are highly hydrolysable, causing the molecular chain to degrade, affecting the stability of the coating and the coating solution and the performance of the coating.

Shenzhen Anpin Silicone Material Co., Ltd. is a high-tech enterprise dedicated to the research, development, production, and operation of water-based paint emulsions, electronic adhesives, thermal conductive encapsulants, thermal conductive silicon grease, thermal conductive soft film, and other new materials. 

http://www.apsi.cn/