Coating classification: silica matting agent

Core tip: Introduction: The matting agent in the coating is a kind of assistant which can change the optical properties of the coating surface This kind of additives can produce the expected micro roughness on the surface of the film, which can significantly reduce the gloss of the film This is necessary for some high-grade architectural coatings with simple and elegant decorative effect Fillers (such as light calcium carbonate and talcum powder) can be used in matte coatings, but the amount of fillers needed is high, which often exceeds the critical pigment concentration of the coating and makes the physical properties of the coating worse The use of matting agents can avoid this problem The commonly used matting agents are divided into organic and inorganic categories Inorganic matting agent Paint agent, top 10 Chinese wall paint brands Recommended introduction: interior wall paint and exterior wall paint can achieve beautiful, clean and pleasant effects, but the effects in different environments are different, so the color of the paint will be different There are ten brands of Chinese paint, ten brands of global paint, ten brands of Chinese wall paint, and ten brands of Chinese paint, Famous trademark of Chinese paint and coating In private rooms, most of us choose according to our own personality, personal hobbies and living habits The younger generation will choose the interior wall paint with rich colors and bright colors, while the older ones will have some working experience Home of coatings: brief introduction: the matting agent in coatings is a kind of additive that can change the optical properties of the coating surface This kind of additives can produce the expected micro roughness on the surface of the film, which can significantly reduce the gloss of the film This is necessary for some high-grade architectural coatings with simple and elegant decorative effect Fillers (such as light calcium carbonate and talcum powder) can be used in matte coatings, but the amount of fillers needed is high, which often exceeds the critical pigment concentration of the coating and makes the physical properties of the coating worse The use of matting agents can avoid this problem The commonly used matting agents are divided into organic and inorganic categories The most important type of inorganic matting agent is silica matting agent Type: silica used as a coating matting agent mainly contains silica, which can be divided into two types: fumed silica and precipitated silica The microstructure of these two kinds of silica is amorphous or glassy The natural silica commodity is quartz powder, which can only be used as filler in the coating, and has no extinction effect The synthetic silica is mainly composed of natural quartz sand, which reacts with sodium hydroxide or sodium carbonate at high temperature to form sodium silicate, and then through different processes to produce fumed silica or precipitated silica Compared with natural silica, synthetic silica has higher purity and inertia Features: easy to disperse; good extinction performance, low dosage can produce strong extinction performance; little interference to the transparency of the film; little impact on the mechanical and chemical properties of the film; good suspension in the liquid coating, long-term storage, no hard precipitation; little impact on the fluidity of the coating material; high chemical inertia Physical properties: the main physical properties of silica are particle size, porosity and density Synthetic silica is not a solid particle, but a sponge like porous particle with a large number of pores filled with air Therefore, the density of synthesized silica is very low The number of silica particles per unit mass of silica with high porosity is much lower than that with low porosity Because the decrease of glossiness is particle effect, the high porosity silica has better extinction effect for a given particle size The average particle size distribution of silica plays an important role in the reduction of gloss For a given coating and film thickness, the best extinction effect is obtained at the best particle size distribution The wide range of particle size distribution indicates that there are a large number of "fine" and "coarse" particles In addition to the poor extinction effect of these two kinds of particles, "fine" particles will also increase the viscosity of the coating; "coarse" particles will make the surface of the coating excessively rough Extinction principle: the extinction principle can be summed up in two ways: one is to increase the surface roughness of the coating, the other is to reduce the reflective strength of the substrate It is not difficult to understand the mechanism of increasing the surface coating roughness to achieve the extinction effect: when the light hits an absolutely smooth plane, the light will completely reflect along the same direction, i.e specular reflection; when the light hits a rough surface, the light will reflect along all directions, i.e diffuse reflection As shown in Figure 1 below When silica is dispersed in the finishing agent, a heterogeneous film will be formed between the particles and the two phases of the system, which will cause the nonuniformity of the refractive index The light intensity of the substrate through the nonuniform film must be lost, which will reduce the reflective intensity of the substrate, so as to achieve the extinction effect In practical application, the realization of extinction effect is often the cooperation of the above two effects Application: silica matting agent has a wide range of applications in the coating industry, and its applicable coating varieties are excellent: water-based and solvent-based transparent wood coatings (wood varnish), water-based and Solvent-based wood coatings, high solid coatings, acid catalytic coatings, architectural coatings, electrodeposition primer, fabric coatings, ethylene coatings, military coatings, wallpaper coatings, PVC Plastic coating, etc Home of coatings is specialized in coatings, diatom mud, paint coating, coating technology, fire retardant coating news and coating, diatom mud, paint coating, coating technology, fire retardant coating decoration knowledge and decoration renderings,