Raise ceaselessly as people living standard, on the one hand consumer feels the bright light coating after becoming film of high burnish glances more serious, harmful to the eye of the person;On the other hand, consumers' aesthetic concept is more and more inclined to be casual, fashionable and personalized.Therefore, when we use matting powder, we should also consider how to use matting powder comprehensively.What are the factors that affect matting powder?
First of all, what are the factors affecting gloss and gloss?
Light rays cast onto the surface of the object will occur light reflection, the object surface light reflection ability called luster.Different objects on the surface of the gloss is not the same, measuring the amount of light reflection on the surface of the object, called gloss.Gloss is expressed as a percentage.The more shiny a surface is, the more light it reflects and the brighter it is.The degree of gloss is determined by photoelectric gloss instrument.According to the size of glossiness, coating can be divided into light, matt, matt and so on.Classification of paint gloss (take the reflection gloss of 60° (that is, the incidence Angle of light is 60°) as an example) :
Matt paint: gloss < 10%;
Matt coating: 15 ~ 60% gloss;
Gloss: BBB 0 % gloss.
Factors affecting the luster of matte powder:
(1) coating surface roughness
The surface gloss of an object is closely related to the roughness of its surface.When light hits a surface, some of it is absorbed, some is reflected and scattered, and some is refracted.The smaller the surface roughness, the more light is reflected and the higher the gloss.Conversely, if the surface of an object is uneven, more light will be scattered, resulting in a decrease in gloss.The surface roughness (h) of the shiny object can be perceived by human vision. Using the theory of micro-surface, we can calculate the wavelength of light emitted by human according to the formula: h = lambda /cos alpha.Alpha is the Angle of incidence.For example, when the human emission Angle is 60°, we can calculate h= 1.1m. When the surface roughness of the object is greater than 1.1m, it will show uneven, low gloss.
(2) film formation process
Coating coating on the surface of the object, through the volatilization of the solvent and solidified into a film (for solvent-based coatings).The formation process of coating film is very important to the surface roughness and luster of coating film.In the wet film stage, the volatilization rate of solvent is controlled by the diffusion of solvent on the coating surface.On the contrary, when the solvent components in the wet film phase of volatilization rate is not the same, it will make polymer molecules tend to form crimp, or even precipitation, into different sizes of particles or clusters, coating surface appears uneven.In the dry film stage, the solvent volatilization rate is mainly controlled by the diffusion of solvent in the whole coating, which will also affect the roughness of the coating surface.In addition, in the formation process of coating film, with the solvent volatilization, coating film will become thin and shrink, some suspended heavy particles in the coating film surface will be rearranged, causing the film surface is not flat.
(3) pigment, fine particle size and distribution
The particle size and particle size distribution of pigment is one of the important factors affecting the gloss of coating.It has been found that when the diameter of pigment particles is less than 0.3 microns, a high gloss coating can be obtained.The reason is: dispersed in the paint pigment particles in a certain thickness of the coating film, and dry, only upper pigment particles local ground process, particle diameter less than 0.3 micron pigment ion caused by the coating film surface roughness will not exceed 0.1 micron.When the average particle diameter of pigment is between 3 and 5 microns, the coating film with better extinction effect can be obtained.In addition to the above three factors can affect the gloss of the coated film surface, pigment volume concentration (PVC), pigment dispersion, as well as the structure and surface reflection characteristics of the coated film surface can also affect the gloss of the coated film surface.Among them, with the increase of pigment PVC, the gloss on the coating surface first decreases, and a minimum value appears at the limit volume concentration of pigment (CPVC), 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.
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