With the continuous improvement of people's living standards, on the one hand, consumers feel that high-gloss bright paints are more reflective after film formation, which is harmful to people's eyes; on the other hand, consumers' aesthetic concepts are more and more inclined to leisure, fashion and personalise. Therefore, when we use matting powder, we must also consider how to use matting powder. Let me tell you about the factors that affect the matting powder.
First, light is reflected off the surface of an object. The ability of the surface to reflect light is called luster.Different object surface gloss is not the same, measuring the size of the surface of the light reflection, called gloss.Gloss is expressed as a percentage.The higher the glossiness of an object's surface, the stronger its ability to reflect light and the higher its brightness.The degree of glossiness is determined by photoelectric gloss meter.The size that spends according to glossiness, can divide coating to wait for a few kinds of light, matte, without light.
The classification of gloss of coatings (taking 60° reflective gloss (i.e., 60° incident Angle of light) as an example) :
Matt coating: gloss < 10%;
Matte coating: gloss 15 ~ 60%;
Gloss: gloss 60 % >.
Factors affecting the luster of matting powder:
(1) coating surface roughness
Surface gloss is closely related to the roughness of an object's surface.When light hits a surface, some of it is absorbed, some is reflected and scattered, and some is refracted.The smaller the roughness of the surface, the more light is reflected and the higher the gloss.On the contrary, if the surface of an object is uneven, more light will be scattered, resulting in a decrease in gloss.
Human vision can feel the surface roughness of the bright object (h), the use of microsurface theory, can be calculated according to the formula: h = lambda /cos alpha, into the human light wavelength;Alpha is the incident Angle.For example, when the Angle of firing is 60°, h=1.1 microns can be calculated. When the surface roughness of the object is greater than 1.1 microns, it will show uneven appearance and reduce the gloss.
(2) the film forming process of the film
Coating brush on the surface of the object, through solvent volatilization and curing into a film (for solvent based coatings).The formation process of coating film is very important to the roughness and gloss of coating film.In the wet film stage, the solvent volatilization rate is controlled by the solvent diffusion on the coating surface.Conversely, when the solvent components in the wet film stage of the volatilization rate is not the same, it will make the polymer molecules tend to form curl, or even precipitation, into different sizes of particles or clusters, coating surface appears uneven.In the dry film stage, the rate of solvent volatilization is mainly controlled by the diffusion of solvent in the coating whole, and also affects the roughness of the coating surface.In addition, in the formation process of coating film, along with the solvent volatilization, coating film will become thinner and shrink, some of the heavy particles suspended in the coating film surface will be rearranged, causing the uneven surface of coating film.
（3）The size and distribution of pigments and fine materials
The particle size and particle size distribution of pigment is one of the important factors affecting the gloss of coating.In the study, it was found that the pigment particles were less than 0.3 microns in diameter when they produced a high gloss coating.The reason is that when the pigment particles dispersed in the coating are made into a certain thickness of coating film and dried, only the pigment particles in the upper layer are partially above ground, and the roughness of the coating film surface caused by the pigment ions with the particle diameter less than 0.3 microns will not exceed 0.1 microns.When the average particle diameter of the pigment is between 3 and 5 muon, the film with better extinction effect can be obtained.In addition to the above three factors can affect the gloss of the coating surface, such factors as the volume concentration of pigment (PVC), dispersion of pigment, surface structure and surface reflection characteristics of the coating can also affect the gloss of the coating surface.Among them, with the increase of PVC of pigment, the gloss of the coating surface first decreases, and a minimum value appears at the CPVC of pigment, and then with the increase of PVC, the gloss also increases.When the type and amount of pigment is determined, the better the dispersion, the higher the gloss of the coating surface.
Contact Person: Mr. Don