Coatings have four major components: film-forming substances, color fillers, solvents, and additive additives. With the increasing global attention to environmental protection, the application of water-based coating additives has become more and more extensive, with leaps and bounds, and new environmentally friendly types of additives are becoming more and more available.
Wax emulsion or wax powder: improve the scratch resistance of the paint film and improve its handfeel.
Principles of wax application in coatings
The wax is mainly added in the form of additive, the general amount of addition is about 0.1%-3%, depending on the type of resin used in the actual formulation, the final performance to be achieved, the performance mainly refers to the appearance (the effect seen by the eyes), touch (by touching the amount of feeling) and some other physical performance requirements and choose the type of wax powder and its filling amount.
Application of wax additives in paint and its mechanism
Waxes can effectively improve the surface properties of the coating film. It mainly includes improving the smoothness of coating film, scratch resistance, water resistance, changing the rheological properties of coating, matting agent, the specific roles and mechanisms are as follows.
1, Anti-slip, anti-adhesion, stain resistance
Fat sticky mainly refers to the adhesion between the coating film and the coating surface and external substances, as well as exposure to the atmosphere to dust, staining and pressure and adhesion. Wax additives can effectively solve the problem of anti-adhesion.
Principle of action: The wax additives in the coating system will gradually migrate to the surface of the film in a uniform manner during the process of film drying. Gradually, a wax film is formed on the surface of the film, which can make the coating surface anti-adhesive, and at the same time produce synchronous effects such as anti-abrasion and anti-scratch.
How the wax migrates to the surface in the coating film is related to the interaction between the wax and the coating, the drying form, the thickness of the film, the strength of the wax, the dispersion state and the density of the wax.
Ammonia volatilization in the coating film, or replacement of ammonia ions by metal ions, causes the wax particles to lose their hydrophilicity. The wax particles with hydrophobic properties easily precipitate out of the paint film. The wax precipitates out of the paint film and changes the surface composition of the film, and the surface tension of the film is reduced from 40-50 mN/m of the general resin to about 30 mN/m. With PTFE wax, the surface tension can be reduced to about 18.5mN/m, which has obvious anti-adhesive and anti-stain effect.
2, Abrasion and scratch resistance
One factor to improve anti-friction and anti-scratch is to reduce the friction coefficient of the coating surface, so that when the object contacts the coating surface, the sliding tendency is greater than the scratching tendency. Wax micronized powder migrates to the surface of the coating film can make the surface of the coating film can make the dynamic friction coefficient of the surface of the coating film reduced significantly, and only a small amount is needed to achieve anti-scratch. Wax micronized powder added to the coating can make the coating film greatly reduce the tendency of being polished by friction, while maintaining the durability of low gloss.
3, Anti-sagging, anti-sedimentation
Large specific surface area of micronized powder. Localization of metallic pigments. Wax dispersion in aromatic and aliphatic solvents can increase the anti-sedimentation of coatings and inks, it also shows different degrees of thixotropy, anti-sagging and the positioning of metal pigments.
4, Melting effect
Gloss is the ability of the surface of the paint film to reflect the light projected on it in one direction, the greater the amount of reflected light, the higher the gloss. Migration to the surface of the coating film to the wax particles, through refraction, diffusion, etc., so that the reflection of light projected on the surface of the coating film and other light in the same direction is weakened, to achieve the matting effect. The matting effect of wax micronized powder varies greatly with different particle sizes and varieties, ranging from complete gloss retention to deep matting. You can add different particle sizes and amounts of wax powder to control the intensity of matting of the coating surface.
5, Feel and appearance effect
Some wax additives can effectively improve the feel of the coating surface, so that the coating has a good sense of wax and silky feeling. It will make the surface of the coating film have a very unique visual effect, usually people call it wax sense.
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