"Water-based paint manufacturers have honed their swords for ten years, and now it’s time to shine." Zhu Yanan, secretary general of China Water-based Wood Coatings Technology Alliance, said in an interview with a reporter from China Chemical Industry News recently. The new environmental protection policy is becoming more and more stringent, and consumers' health awareness continues to increase, and high-VOCs coatings seem to be exhausted. However, according to a reporter from China Chemical Industry News, in wood coatings, the water-based ratio is far below 10%. In addition to the low acceptance by downstream companies, the application cost and product performance of water-based coatings are still unsatisfactory. In the face of the coming waterborne era, what new requirements have been put forward for supporting resins, coloring systems, additives, etc.? How should raw material manufacturers respond? A reporter from China Chemical Industry News conducted extensive interviews.

Resin R&D should be a system

Yang Huan, Marketing Service Manager of Wanhua Chemical Group Co., Ltd. believes that the further oil-to-water conversion of wood lacquer will mainly face the following technical challenges: one is the insufficient hardness of the paint film, the other is the difficulty of achieving a fully enclosed effect, and the third is the problem of wood swelling. Fourth, the drying process is greatly affected by the environment. A reporter from China Chemical Industry News learned that most of the performance of coatings is realized by resin. The key to water-based wood coatings depends on the performance and cost of water-based resins.

Yang Huan pointed out that different areas of furniture use have different requirements for coating performance. For example, outdoor furniture requires water-resistant and water-white coatings, and has high requirements for weather resistance and flexibility; indoor furniture requires high hardness, appearance, chemical resistance, and mechanical properties. This requires targeted selection of different resin systems into the formulation design. From the resin point of view, there are also many classifications of oil-based coating resins, such as nitrocellulose paint, PU paint, UV paint and so on. The resins used in wood coatings are mostly acrylic emulsions. Although low cost, fast drying, and good sanding properties, they have a single performance and are difficult to compare with the above-mentioned oil-based paints. Therefore, more water-based resin systems are needed to form an overall effect to replace oily paints. Resin. How to improve the performance, how to reduce the sensitivity of the paint film to the environment during the drying process, how to solve the problem of swelling, and how to improve the wettability of the water-based resin to the wood, all need to be solved by the resin supplier. The PUD, PUA, water-based UV, water-based two-component systems that have been successfully developed so far have given downstream users more choices.

Hua Dongshuan, deputy general manager of Hebei Chenyang Industry and Trade Group Co., Ltd., said in an interview that the rapid development of new chemical materials provides a strong guarantee for the optimization of water-based coating performance. At present, water-based resins from multinational companies such as Opel Di and DSM are more widely used in China. The water-based resin products produced by domestic enterprises still have room for improvement in terms of performance index stability. "For example, the temperature control in emulsion production is very critical. If the temperature control equipment is not sensitive, there will be a wide range of temperature fluctuations, resulting in performance differences between batches outside the allowable error. Domestic companies In terms of means, there is still a big gap compared with international manufacturers. At present, some companies have introduced foreign production equipment to implement fully automated control. Only when the equipment has a high degree of automation and precise control can product performance indicators be stable, and downstream companies are also Only in order to produce stable products." Hua Dongshuan said.

The coloring system should be water permeable

Due to the different solvents, the requirements of water-based paints in coloring systems are quite different from those of oil-based paints, which has given birth to the development of water-based coloring systems.

According to Shu Han, technical engineer of Dongguan Caizhihong Chemical Co., Ltd., color essence is a coloring scheme for transparent colors in the coating industry, and it plays an increasingly important role in the application of water-based coatings. Good water-based color concentrates not only need to have good compatibility with water-based paints, but also the toners used must have good fire resistance, temperature resistance, color migration resistance and sufficient brightness, and have solvent-based performance. All the features of the product can be better accepted by users.

At present, the transparent coloring systems used in water-based systems on the market mainly include acid dyes and metal complex color fine systems. Acid dyes are easy to react with weakly alkaline water-based paints and are easy to fade. The previous metal complex color concentrates require the dissolution of organic solvents, and the cost is relatively high. In order to adapt to the application of water-based coatings, Caizhihong has developed a series of coloring products such as CH-W121 water-based yellow concentrate, CH-W721 water-based brown concentrate, CH-W823 water-based black concentrate, and CH-223 water-based orange concentrate. The metal complex pigments in these water-based color concentrates are not completely miscible in the water-based system, but a stable dispersion state.

Industry experts pointed out that color pastes are also a large category of products in water-based paint coloring systems. With the water-based coatings, color pastes that can be used with water-based coatings have great room for development in the future. Water-based transparent colorant is mainly used for wood coloring and top coat of higher-end cars. After using transparent color paste for woodware Grace, the wood grain can be well displayed and the quality of woodware can be improved. The use of transparent color paste in automotive coatings with aluminum silver paste and pearlescent pigments can improve the effect of automotive coatings. Water-based solid color pastes are widely used in water-based industrial coating coloring systems, and their performance is closely related to the light resistance, weather resistance and chemical resistance of the pigment itself.

As the amount of water-based paint continues to increase in the future, water-based coloring systems will become more and more mature, which can provide downstream users with more personalized solutions.

Additives need to be recruited

It is understood that the main difference between water-based paint and oil-based paint is the solvent. Coating film formation, flow and leveling, and paint film performance are all closely related to solvents. There are many kinds of solvents for oil-based coatings, and the solvent can be adjusted according to needs. However, water-based coatings only have water and a small amount of coexisting solvents. It is difficult to achieve the film-forming, flow and leveling properties of oil-based coatings, and additives need to be added for adjustment.

The reporter learned from an interview that theoretically, water-based emulsions can obtain better physical and chemical properties than oil-based systems due to their higher molecular weight. However, since the raw materials of the oily system have been fully developed, technical research and development personnel can obtain high-performance coatings through special raw material selection or additives. In contrast, water-based products are not very abundant, and there is no emulsion with superior performance to choose from. The correct use of film-forming additives and the combination of additives suitable for the system to improve the performance of the paint film is very critical.

It is foreseeable that as the process of oil-to-water conversion accelerates, a batch of new film-forming additives, rheology additives, leveling agents, cross-linking agents, and functional fillers suitable for water-based coatings will emerge.

In addition, because the water-based wood coating formulation contains a large amount of organic substances, it is very suitable for the growth of microorganisms. Microbial mucus will decompose the components in the wood coating, affect the fluidity of the product and other properties, cause the product to deteriorate and affect its use. Therefore, it is very necessary to control the growth of microorganisms. The preservatives in the tank need to have the following characteristics: broad-spectrum antibacterial, a wide range of pH applications, meet the protection requirements under process conditions, safe operation, good compatibility, low dosage, and meet relevant regulatory requirements .