The application of wax in paint, wax was used as a paint matting agent earlier, and its characteristic is that it is easy to use. After the paint is applied, due to the volatilization of the solvent, the wax in the paint is precipitated, forming fine crystals, floating on the surface of the paint film, forming a rough surface that scatters light and plays the role of matting.
Now except for high molecular weight mineral waxes, natural waxes are rarely used in paints, replaced by high molecular weight waxes and their modified derivatives. They not only have good matting effect, but also can endow the paint film with good water resistance, heat and humidity resistance, scratch resistance, anti-sticking and stain resistance, and have good hand feeling. Their scratch resistance is beyond the reach of pigment matting.
The polymer wax of oxidized polyolefin wax is used as a matting agent, its dosage is 0.5-3%, it is suitable for acrylic paint, alkyd paint, nitro paint and polyurethane paint, industrial baking paint, vinyl Lacquer and latex paint. The combination of polymer wax and fumed silica can make the performance of the paint film more perfect, and its matting effect, water resistance, chemical resistance, scratch resistance, abrasion resistance and interlayer adhesion are all significantly improved.
Oxidized polyethylene wax is a low molecular weight polyethylene homopolymer or copolymer widely used in coatings. The so-called wax means that the polymer is finally distributed in the form of microcrystals on the surface of the coating to play a role similar to wax but more diverse.
Wax can effectively improve the surface properties of the coating film. It mainly includes improving the smoothness and scratch resistance of the coating film, improving water resistance, changing the rheological properties of the coating, and matting agent. The specific functions and mechanisms are as follows:
1. Non-slip, anti-adhesion, stain-resistant
Stickiness mainly refers to the adhesion between the coating film and the surface of the coating and foreign substances, as well as the adhesion of dust, dirt and pressure when exposed to the atmosphere. Wax additives can effectively solve anti-blocking properties.
Principle of action: The wax additives in the coating system will migrate to the surface of the film evenly and gradually during the drying process of the film. A layer of wax film is gradually formed on the surface of the film, which can make the surface of the paint anti-adhesion, and at the same time produce synchronous effects such as anti-wear 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.
2. Anti-abrasion and anti-scratch
One of the factors to improve friction and scratch resistance is to reduce the friction coefficient of the coating surface, so that when an object touches the coating surface, the sliding tendency is greater than the scratching tendency. The migration of wax micropowder to the surface of the coating film can greatly reduce the dynamic friction coefficient of the coating film surface, and only a small amount is needed to achieve scratch resistance. Adding wax micropowder into the coating can greatly reduce the tendency of the coating film to be polished by friction, while maintaining the durability of low gloss.
3. Anti-sag, anti-sedimentation
Micropowder has a large specific surface area. Positioning for metallic pigments. Wax is dispersed in aromatic and aliphatic solvents, which can increase the anti-sedimentation of coatings and inks. It also shows different degrees of thixotropy, anti-sagging and positioning of metallic pigments.
4. Extinguishing effect
Glossiness 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 glossiness. Migrate to the surface of the coating film to wax particles, through refraction, diffusion, etc., to weaken the reflection of light projected on the painted surface in the same direction to achieve a matting effect. Wax micropowders of different particle sizes and varieties have very different matting effects, from completely maintaining gloss to deep matting. The matting strength of the coating surface can be controlled by adding different particle sizes and amounts of wax powder.
5. Hand feel and perception effect
Some wax additives can effectively improve the feel of the coating surface, making the coating have a good waxy and silky feel. It will make the surface of the coating film have a very unique visual effect, which is usually called waxy.
The main functions of polyolefin wax in solvent-based coating films are: matting, anti-sedimentation, thixotropy, good lubrication and processability, and metal positioning.
High temperature should be avoided when adding oxidized polyolefin wax micropowder into the coating, because the polyolefin wax will dissolve in the solvent at high temperature, and will precipitate out when cooling to form larger particles. The effect of polyethylene wax depends on the following factors: the type and specification of polyethylene wax, the fineness of the final particles, the ability to migrate to the surface of the coating and the composition of the coating, the nature of the substrate to be coated, and the application method. law etc.
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