【Detail】
Application of PVP in Organic Pigments
Organic pigment particles through chemical synthesis methods has great specific surface area, and the area is 8~100m2/g. Usually the pigment particles by mechanical processing reach70~100 micron, and cannot be used directly. So people change some characters of pigments by surface treatment technology, such as dispersion, heat stability, solubility of resistance, chemical inertness and light solid performance. In fact, the surface treatment is to stop the particles to grow up with some method before they gather into large particles. The best method is to protect paint particles, endowed with necessary performance.
PVP has good film forming, soluble in water and insoluble in some organic solvents, and most organic solvents for paint solvent. PVP with the more molecular weight, the more excellent film forming. When poor solubility in organic solvents, PVP ( molecular weight greater than 30,000 ) is used to process pigment granules. As a result of PVP affinity of pigment molecules on the surface of the formation of a layer of transparent paint films, forming a membrane insoluble in organic solvents, so it is hard to destroy. When using no color diffusion phenomena, it does not affect the true colors, and can increase the gloss and the dispersion of pigments, separate organic pigments from the external environment. Thereby it indirectly gives chemical stability and thermal stability of organic pigments, avoids chemical reaction between certain substances and the external environment caused by light and heat, and improves pigment light solid performance. It is typically used for surface treatment of organic pigment of PVP-K30,PVP-K90 and PVP-VA64. After PVP processing organic pigment particle, the size is 0.1~10 microns. PVP used for the main surface treatment in paints: protective and decorative coatings, such as varnishes, paints, etc ; aqueous dispersions; printing, ink, color and fabric in plastic paint, latex, and so on. PVP excellent dispersion properties can also be used for carbon black, pigments, titanium dioxide, and other phthalocyanine pigment dispersion.
Application of PVP in paints and coatings
In water - soluble resin emulsion paints and coatings, because of bad dispersion of pigments and when storage coagulation precipitation resultes in color floating , poor sheen behavior. Medium molecular weight of PVP (PVP-K30 ) added can enhance coloring power , eliminate floating color phenomenon, disperse and stabilize pigment composition, improve the luster to avoid paint flocculation and sedimentation. styrene and methyl acrylate as main body, emulsion coating viscosity is often very low, resulting in coating of poor water resistance. when daub, liquidity is too big. Coating thickness is not easy to control, and when the hardness is not enough, it will fall off. So it needs to go through the thickening, sticky process.In this type of emulsion by adding the amount of PVP, with the evaporating concentration to the viscosity of more than 10 times , to get high viscosity stability of synthetic resin solution. PVP thickening coating emulsion for coatings blending with no sagging, good water resistance of coatings and coating advantages of hardness, no shedding, tolerance.
Transparent coating of papers containing PVP let jet printing ink on top of its fast - drying, with good water ink, insoluble in water, has good fixity and proliferation. In addition, the PVP has important use of other coatings, such as conductive coating ,electrode coating, Leakage-proof coating. As in the insulating layer of conductive material, after repeated sudden heat, sudden cold, sun and rain, wears out or break, or because of water seepage and leakage. In the insulation of the external form a PVP film ( PVP-K90 ), on the one hand, PVP is transparent film, does not affect the insulation qualities; on the other hand, the PVP films and insulating layers bonded together, separating insulation from light, heat,and rain, isolated from the outside world to prevent water leakage caused by the bursting phenomena, reduce aging rate caused by light and heat, and extend the life of the wires, but also appropriate to increase the hardness of the wire.
