Application in the paint and ink industry

Application of PVP in Organic Pigments：

The organic pigment particles obtained by chemical synthesis methods have a large specific surface area range, with a specific surface area of 8-100m2/g. Conventional mechanical treatment methods can only achieve a pigment particle size of 70-100 microns and cannot be directly used. So people use surface treatment techniques to change certain properties of pigments, such as dispersibility, thermal stability, solubility resistance, chemical inertness, and photopolymerization performance. In fact, surface treatment of pigments is to use some method to prevent their particle growth before they aggregate into large particles. The best method is to protect the pigment particles and give them the desired performance.

PVP has good film-forming properties, soluble in water but insoluble in certain organic solvents. Most substances used as pigment solvents are organic solvents, and PVP has better film-forming properties with increasing molecular weight. When the solubility of organic solvents is poor, PVP (molecular weight greater than 30000) is used to treat pigment particles. Due to the affinity between PVP and pigment molecules, a transparent thin film is formed on the surface of the pigment. The formed film is not suitable for dissolution in organic solvents, so it is not easily damaged. When used, it will not cause pigment diffusion, will not affect the natural color, and can improve the luster and dispersibility of the pigment. It isolates the contact between organic pigments and the external environment, indirectly endows the organic pigment with chemical stability and thermal stability, avoids chemical reactions caused by certain substances or light and heat in the external environment, and improves the photopolymerization performance of the pigment. The PVP commonly used for surface treatment of organic pigments is PVP-K30, PVP-K90, or PVP VA64. The particle size of organic pigment particles after PVP treatment is between 0.1-10 microns. The dosage of PVP is generally 5-10% of the mass of organic pigments. The pigments that can be surface treated with PVP mainly include protective and decorative coatings, such as varnish, paint, etc; Aqueous dispersion system; Printing, ink, fabric coloring, plastic coloring, latex, etc.

The excellent dispersibility of PVP can also be used for the dispersion of various pigments such as carbon black, phthalocyanine pigments, titanium dioxide, etc.

Application of PVP in Coatings：

In lotion coatings and water-soluble resin coatings, poor dispersion of pigments and coagulation and precipitation during storage reduce the coloring effect, resulting in floating color, poor gloss and other undesirable phenomena. Adding medium molecular weight PVP (PVPK30) can improve coloring power, eliminate floating phenomenon, disperse and stabilize pigment components, improve gloss, and avoid pigment flocculation and precipitation. The viscosity of lotion coating mainly composed of styrene and methacrylate is often very low, resulting in poor water resistance of the coating. The fluidity is too large when applying, the thickness of the film is difficult to control, and the hardness is not enough, which will fall off. Therefore, it needs thickening and tackifying treatment. The viscosity of this kind of lotion can be increased by more than 10 times after adding appropriate PVP into the emulsion through evaporation and concentration, and a stable synthetic resin solution with high viscosity can be obtained. The coating lotion made of PVP tackifying coating has the advantages of no sagging, good water resistance, hard film, no falling off, and stain resistance.

The transparent coating of paper containing PVP allows the printing ink to dry quickly on it, has good ink absorption, is insoluble in water, and has good solidification and diffusion properties. In addition, PVP has important applications in other coatings such as conductive coatings, electrode coatings, and anti leakage coatings. If the insulation layer outside the conductive material is subjected to repeated rapid heating, cooling, sun and rain exposure, it will age or break, or leak electricity due to water leakage. A layer of PVP film (PVPK90) is formed on the outside of the insulation layer. On the one hand, the PVP film is transparent and does not affect the natural color of the insulation layer. On the other hand, the PVP film is bonded to the insulation layer, isolating it from external light, heat, rain, etc., avoiding leakage caused by water seepage and cracking, reducing the aging rate caused by light and heat, extending the service life of the wire, and appropriately increasing the hardness of the wire.