Gloss (GB/T1743-89)
The light is projected on the surface of the coating film at a certain incident angle, and the amount of light reflected at the corresponding angle is the glossiness. The test principle is shown in Figure 3_8_1.
Under a certain incident angle, the surface of the coating film is rough, the flatness is poor, the scattered light is more, the reflected light is less, and the gloss is low. The coating gloss measured by 60% gloss meter is classified as follows:
As the incident angle increases, the intensity of reflected light increases. According to the regulations of ASTMD523, for high-gloss coatings exceeding 70%, it is declared to be measured by a 20° incident angle Glossmeter. Conversely, for low-gloss coating films below 30%, an 85° gloss meter should be used for measurement.
According to the regulations of IS02813, the gloss range of 60° gloss meter is 30%~70%. For high gloss, the gloss data of 20° and 60° should be given at the same time. At this time, for ease of use, a multi-angle (or variable-angle) Glossmeter can also be used to measure the gloss under different incident light.
For flash paint, a multi-angle Spectrophotometer can be used to test the flash effect. Such as the MA58 (25°, 45°, 75°) and MA68 (15°, 25°, 45°, 75°, 110°) of the American x_Rite series. The incident light remains constant at an angle of 45°, and the reflected light intensity is detected at different observation angles [see Figure 3_8_2(a)]. When the Yichang powder is arranged in parallel in the coating film, the specular reflection has the maximum reflected light intensity, and the greater the angle of deviation from the specular reflection, the stronger the scattered light and the weaker the received reflected light [see Figure 3_8_2(b)]. In the graph of the light intensity signal of the photocell and the observation angle, if the peak is higher and the peak width is narrower, then when observed from different angles, the light and shade changes of the reflected light are stronger, the flashing effect of the flash paint is stronger, and the flashing effect is greater. good.
For the color difference of the flash paint, it can be measured by the CR353 (25°, 95°) two-angle and cR354 (15°, 45°, 110°) three-angle Colorimeters of Japan MI_NOLTA.
