Wax is used as an additive for paints and inks. Its characteristics are simple to use. After the paint is applied, due to the volatilization of the solvent, the wax in the coating precipitates, forming fine crystals, floating on the surface of the coating film, and plays a variety of roles in improving the film performance. In addition to high-molecular mineral waxes, natural waxes are rarely used in paints and inks, and instead they are high-molecular waxes and their modified derivatives. They can give the coating a good resistance to water, heat and moisture, scratch resistance, matting, anti-smudge, and a good feel, their scratch resistance is not reach the pigment extinction. Author/Yu Tianshi Source: Ink News
As a auxiliant, the polymer wax is used in an amount of 0.5-3%. It is suitable for acrylic paints, alkyd paints, nitrocellulose paints and polyurethane paints, industrial baking paints, vinyl paints, and latex paints. The combination of high-molecular wax and fumed silica can improve the coating performance, and its matting effect, water resistance, chemical resistance, scratch resistance, abrasion resistance, and interlayer adhesion have all improved significantly.
Polyethylene waxes are low molecular weight polyethylene homopolymers or copolymers widely used in coatings. The so-called wax refers to the fact that the final microcrystalline form of the polymer distributed on the surface of the coating acts like a wax and is more versatile.
Waxes play an increasingly important role in paints and inks as auxiliaries.
The role of polyethylene wax depends on the following factors: the specification of the polyethylene wax, the fineness of the final formed particles, the ability to migrate to the surface of the coating, the composition of the coating, the nature of the substrate being coated, and the method of construction application. The following describes the role of polyethylene wax performance:
1. Improve surface gloss
In the application of matting coatings, the amount of silica used in the same range that is effective extinction effect. The amount of matting depends on the particle fineness of the dispersed polyethylene wax and its ability to migrate to the surface of the coating film.
The effects of different waxes on the gloss of the coating are different: from significant extinction to increased luster and to the generation of unusual sheen and hammer marks. Feel: The wax additive gives the coating a good feel, which is something other matting agents cannot achieve.
2. Anti-scratch, anti-wear, anti-polishing, anti-imprinting
One factor to improve friction and scratch resistance is to reduce the coefficient of friction on the surface of the coating. When the object touches the surface of the coating, the sliding tendency is greater than the scratching tendency. The effect of the polyethylene wax is similar to silicone oil. The difference is that the former Fine dispersed particles are present on the surface of the coating. To achieve scratch resistance requires only a small amount.
Polyethylene waxes, added to coatings, can greatly reduce the tendency to be polished due to friction, while maintaining low gloss durability is often desirable in applications. In alkyd varnish, when the amount of polyethylene wax is 1.5%, the anti-wear value of the coating film is doubled, and when the amount is 3%, the anti-wear value is increased by 5 times.
When metal objects come into contact with coated products, they sometimes leave a black mark on the coating. The addition of polyethylene wax to the coating can reduce this tendency, or make the mark easier to wipe off.
The use of micronized wax in printing inks can significantly improve the abrasion resistance of the ink.
3, anti-blocking
Some workpieces, such as wood or metal objects, tend to pile up in a short period of time after the film is coated. Advances in printing technology also require the ink to avoid contamination of the printed material.
Polyethylene waxes prevent sticking and staining caused by the cumulative overlap of production or printed matter.
4, anti-precipitation, anti-sag, thixotropic. Positioning of metallic pigments.
Polyethylene waxes dispersed in aromatic and aliphatic solvents can increase the anti-precipitation properties of coatings and inks. It also shows varying degrees of thixotropy, sag resistance, and localization of metallic pigments.
Polyethylene waxes can be added in paints and inks in a variety of ways:
1. Slurry and micropowder.
Slurry is a pre-dispersed form of polyethylene wax in a solvent and is easily added. Micro powder is one of the most commonly used forms. Multi-brand wax powder is suitable for different types and requirements of coatings and inks, and can be selected according to the physical and chemical properties of wax and particle size distribution. The physical and chemical properties are mainly the properties of the wax itself, such as chemical structure, molecular weight, melting point, penetration, acid value, etc. The particle size refers to the particle diameter and its distribution, particle shape and surface state in micrometers.
2. Emulsions, dispersions.
Emulsions are stable dispersions of waxes in water and usually have particle sizes below 1 μm. Below 200 nm is usually transparent or translucent. Those having a particle size of 1 μm or more are called dispersions or microdispersions.
Aqueous dispersions make the application of polyethylene waxes in aqueous acrylic and polyurethane coatings and inks extremely convenient.
Application of polyethylene wax powder and dispersion in ink