Application of polypropylene wax in coatings and inks

Waxes have been used earlier as additives for coatings and inks, and are characterized by simple use. After the coating is applied, due to the volatilization of the solvent, the wax in the coating will precipitate, forming fine crystals, which float on the surface of the coating film, and play a variety of roles in improving the performance of the coating film. Except for high molecular mineral waxes, natural waxes are rarely used in coatings and inks, replaced by high molecular waxes and their modified derivatives. They can give the coating film good water resistance, damp and heat resistance, scratch resistance, matting resistance, anti-sticking properties, and a good hand feel. Their scratch resistance is beyond the reach of pigment matting. Macromolecule wax is used as an auxiliary agent, and its dosage is 0.5~3%. It is suitable for acrylic paint, alkyd paint, nitro paint and polyurethane paint, industrial baking paint, vinyl paint and latex paint. The combined use of polymer wax and fumed silica can make the film performance more perfect, and its matting effect, water resistance, chemical resistance, scratch resistance, abrasion resistance and interlayer adhesion have been significantly improved. Polypropylene wax is a low molecular weight polypropylene 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 and plays a role similar to wax and more diverse. As additives, waxes are playing an increasingly important role in coatings and inks. The role of polypropylene wax depends on the following factors: the type and specification of polypropylene, the final particle size and the ability to migrate to the surface of the coating film, the composition of the coating, the nature of the substrate to be coated, and the method of construction and application.

The following describes its role:

1. Extinction. Different types of wax have different effects on the gloss of the coating film: from significant matte to increase gloss and produce unusual gloss and hammer lines. Hand feeling: The wax additives make the coating have a good hand feeling, which cannot be achieved by other matting agents.

2. Wear resistance. Anti-scratch, anti-wear, anti-polishing, anti-marking One factor to improve anti-friction and anti-scratch is to reduce the friction coefficient of the coating surface, so that when objects contact the coating surface, the sliding tendency is greater than the scratch tendency. In this regard, polypropylene The role of wax is similar to that of silicone oil, except that the former exists in the form of fine dispersed particles on the surface of the coating. A small amount is required to achieve scratch resistance. Polypropylene wax, added to coatings, can greatly reduce the tendency to be polished by friction, while maintaining low gloss durability is often required in applications. For example, in alkyd varnish, when the amount of polypropylene 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 touch the coated product, they sometimes leave a black mark on the coating film. Adding polypropylene wax to the coating film can reduce this tendency or make the print easy to wipe off. The use of micronized wax in printing ink can significantly improve the abrasion resistance of the ink.
3. Anti-blocking. Some workpieces, such as wood or metal objects, often need to be stacked in a short time after coating. The advancement of printing technology also requires ink to avoid smearing of printed matter. Polyethylene wax can prevent adhesion and contamination caused by the accumulation and overlap of production or printed matter.

4. Anti-sedimentation, anti-sagging and thixotropy. Positioning of metallic pigments. Polyethylene wax is dispersed in aromatic and aliphatic solvents, which can increase the precipitation resistance of coatings and inks. It also shows different degrees of thixotropy, anti-sagging and positioning to metallic pigments.
Polyethylene wax can be added in coatings and inks in many ways:

(1) The slurry and the micropowder slurry are pre-dispersed forms of polyethylene wax in a solvent, which are easy to add. Micronized powder is the most commonly used form. Various brands of wax powder are suitable for coatings and inks of different varieties and requirements, and can be selected according to the physical and chemical properties and particle size distribution of the wax. 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 microns.

(2) Emulsion and dispersion Emulsion is a stable dispersion state of wax in water, usually with a particle size of 1 m or less. Below 200nm, it is usually in a transparent or semi-transparent state. Those with a particle size of 1 m or less are called dispersions or microdispersions. The water-based dispersion makes the application of polyethylene wax in water-based acrylate and polyurethane coatings and inks extremely convenient.