Factors Affecting Gloss and Gloss Measurement of Gloss and Gloss The light is reflected on the surface of the object and the light is reflected. The ability of the surface of the object to reflect light is called the ray applicator. The gloss of the surface of different objects is different. The measure of the ability of the surface of the object to reflect light is called glossiness. Gloss is expressed as a percentage. The higher the gloss of the surface of the object, the stronger its ability to reflect light and the higher the brightness. The size of the gloss was measured by a photoelectric gloss meter. According to the degree of gloss, the paint can be divided into bright, matt, matt and so on.
Classification of paint gloss (as an example of a 60° reflection gloss (ie, a light incident angle of 60°)):
Matte-coated grinding machine material: gloss matt coating: gloss 15~60%;
Bright paint: Gloss > 60%.
Factors Affecting Gloss The roughness of the surface of the coating is closely related to the surface gloss of the object and the roughness of the surface of the object. When light hits the surface of the object, part of it is absorbed by the object, part of it will be reflected and scattered, and some will be refracted. The smaller the roughness of the surface of the object, the more light is reflected and the higher the gloss. On the contrary, if the surface of the object is uneven, the amount of light scattered is increased, resulting in a decrease in gloss.
The roughness (h) of the surface of a bright object that human vision can perceive, using the knowledge of micro-surface theory, can be calculated according to the formula: h = λ/cosα, where the wavelength of the human light is entered; α is the angle of incidence. For example, when the angle of incidence of the person is 60°, h=1.1 μm can be calculated. When the surface roughness h of the object is larger than 1.1 μm, the unevenness is exhibited and the gloss is lowered.
Coating film formation process After the coating material is applied to the surface of the object, it is solidified into a film by solvent evaporation (for solvent-based coatings). The formation of the coating film is critical to the surface roughness and gloss of the coating. In the wet film stage, the evaporation rate of the solvent is controlled by the diffusion of the solvent on the surface of the coating film. When the evaporation rate of each component of the solvent is not much different, it is possible to obtain a high-gloss surface; otherwise, when the components of the solvent are wet When the volatilization rate of the film stage is different, it tends to form a curl or even precipitate out of the polymer molecules, and becomes a particle or agglomerate of a different size, and the surface of the coating film is uneven. In the dry film stage, the evaporation rate of the solvent is mainly controlled by the diffusion of the solvent in the entire application layer, and also affects the roughness of the surface of the coating film. In addition, during the formation of the coating film, as the solvent evaporates, the coating film becomes thinner and shrinks, and some suspended heavy particles in the coating will be newly arranged on the surface of the coating film, resulting in unevenness of the surface of the coating film. .
Particle size and distribution of pigments and fines The particle size and particle size distribution of pigments and fillers in coatings are one of the important factors affecting the gloss of coatings. It has been found in research that when the diameter of the pigment particles is less than 0.3 μm, a coating film having a high gloss of the color wheel can be obtained. The reason is that the pigment particles dispersed in the coating are made into a coating film bar coater of a certain thickness, and after drying, only the uppermost pigment particles locally protrude, and the pigment ions having a particle diameter of less than 0.3 μm are caused by the pigment ions. The surface roughness of the coating film does not exceed 0.1 μm. When the average particle diameter of the pigment is between 3 and 5 μm, a coating film having a good matting effect can be obtained.
In addition to the above three factors can affect the gloss of the surface of the coating film, the volume concentration of the pigment (PVC), the dispersibility of the pigment, and the surface structure of the coating film and the surface reflection characteristics also affect the gloss of the surface of the coating film. Among them, as the PVC of the pigment increases, the gloss of the surface of the coating film first decreases, and a minimum value occurs at the limit volume concentration (CPVC) of the pigment, and then the gloss increases as the PVC increases. When the type and amount of the pigment are determined, the better the dispersion, the higher the gloss of the surface of the coating film.
For more information about the gloss meter, you can browse it: http://
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