Chen Zhenglin talked about the adhesion mechanism and influencing factors analysis of water-based wood coatings

The main factors affecting the adhesion of water-based wood coatings are wood roughness, coating amount of coatings, substrate wetting agent, and additional It is determined by factors such as focus on accelerators, film-forming aids, and film-forming temperature.

One. Wood roughness
Wood roughness directly affects the penetration depth of water-based paint. The greater the roughness, the deeper the penetration of the water paint, the greater the specific surface area of ​​the wood and the paint, and the higher the probability of interaction, so it is helpful to improve the adhesion strength. contribute. The sandpaper mesh becomes larger, the roughness becomes lower and lower, and the adhesion is generally worse.
Two, coating amount
After the thickness of the coating film increases, the water is difficult to volatilize, causing the coating film to shrink in the direction perpendicular to the substrate to be accumulated and strengthened, which weakens the force between the coating film and the substrate; in addition, the stress-bearing parts of the coating film during testing If it becomes larger, any part in the vertical direction will be damaged due to stress, which will affect the integrity of the part, so it is easier to produce incomplete appearance and make the adhesion of the coating film poor. Therefore, under the premise of ensuring the performance of the coating film, the coating film as thin as possible is beneficial to the adhesion.
Three, substrate wetting agent
The degree of wetting of the coating on the substrate directly affects the adhesion performance of the coating film on the substrate. The amount of substrate wetting agent has a certain effect on the adhesion of the water-based wood coating film. With the increase in the amount of substrate wetting agent, the peeling rate of the coating film continues to decrease, and the adhesion of the coating film gradually increases. When the mass fraction of the substrate wetting agent increases to a certain amount, continue to increase the amount of substrate wetting agent, which has little effect on improving the adhesion of the coating film, but affects other properties of the coating film such as leveling and water resistance. Sex and so on.
Four. Adhesion promoters
With the increase in the amount of adhesion promoter, the peeling rate of the coating film decreases, and the adhesion of the coating film increases. When the amount increases to a certain amount, continue to increase the dosage, the adhesion of the coating film will no longer increase, and it will have a greater impact on the viscosity of the coating. Stability is reduced.
Five. Film-forming additives
The film-forming assistant is a small molecule compound, and has good compatibility with the polymer. It can be filled between the segments of adjacent macromolecules, increase the spacing, weaken their mutual force, and eliminate internal stress. Thereby reducing the tendency of coating film embrittlement, can effectively increase the adhesion of the coating film. Increasing the amount of film-forming aids within a certain range can effectively enhance adhesion. This is because the film-forming assistant can reduce the volatilization rate of the solvent water in the water-based coating, and can also relieve the vacancy through diffusion when the polymer is difficult to adapt to the shrinkage vacancy, thereby reducing the internal stress of the coating film and increasing the adhesion of the coating film. When the amount of the film-forming aid exceeds a certain level, the performance of the coating film will decrease, such as decreased hardness, delayed drying, etc., and the overall performance of the coating film will decrease.
VI. Film forming temperature
The film-forming temperature also has an important influence on the water-based wood coatings, especially for emulsions containing cross-linking groups. As the film-forming temperature increases, the peeling rate of the coating film decreases, and the adhesion of the coating film to the wood increases. Because the film-forming temperature increases, the movement of polymer chains is increased, and the internal stress of the coating film is reduced, so that it can form a better film. In addition, the increase in temperature accelerates the cross-linking of polymer segments, increases the cross-linking density of the coating film and the penetration of the coating film to the substrate, thereby enhancing the adhesion of the coating film.