In the production of colored paint, in order to formulate the color paint formula of recolored paint, the method of instrument-assisted color matching is basically adopted, and its efficiency and accuracy are significantly improved compared with manual color matching. Now enumerate the method of using the American ACS computer color matching instrument for computer color matching. The premise is that it is necessary to input the basic data of various standard colors into the computer color matching instrument, that is, to establish a database of basic pigments. The more types of pigments are input, the choice of pigments in the output formula will increase accordingly. If the cost of the pigment types is also input into the computer, the computer color matching instrument can also display the pigment composition formula of the recolor paint with different costs for future reference. choose.
When using the computer color matching instrument to design the pigment composition formula of the re-color paint, the Spectrophotometer of the computer color matching instrument should be used to measure the L, a, b value of the standard sample color and the pigment composition formula of the color, and display it on the computer monitor. Then print out the color spectrum curve and formula of the standard template by the printer. In this way, when mixing paint, according to the pigment composition given by the computer color matching instrument, a small sample can be prepared in the laboratory, and then the plate is dried and then put into the Spectrophotometer of the computer color matching instrument for color measurement, and the prepared sample is displayed on the display screen. The spectral curve and L, a, b value of the standard sample, and compared with the spectral curve of the standard sample, adjusted according to the deviation of the curve and the comparison with the L, a, b value of the standard sample. Generally, 1 or 2 adjustments can meet the requirements.
Control color difference is measured by △E* value:
In the formula, △L*——lightness difference
△a*, △b*——color difference
Usually the color difference △E value of the solid color paint should be in the range of <1, and the color difference △E value of the metallic flash paint containing aluminum powder and pearl powder is generally <4. This is because the addition of metallic pigments causes changes in the dynamic color index (Flop index). For this reason, when measuring metallic glitter containing metallic pigments, a multi-angle color measuring instrument is required. At present, the MA-58 and MA-68 multi-angle Spectrophotometer s produced by the American x-Rite company have been widely used in various international automobile industries and automotive paint manufacturers. In 1994, the domestic MA-68 multi-angle metal Paint computer color measuring instrument, which plays a role in improving the color control level of paint production, and also helps to catch up with the professional level of international automotive coatings.
Because color science is a multidisciplinary research field, including physiology, psychology, physics, metrology, etc. The effective application of color is based on the color science. The birth of color measurement science—colorimetry makes the color not only qualitatively described, but also has a quantitative measurement method. The chromaticity coordinates and tristimulus values of the International Commission on Illumination (CIE) chromaticity system can be used for calibration, and the color difference can be calculated according to the CIE color difference formula to make the color description accurate. In order to calibrate the surface color more easily, several color systems have been established internationally, including the Munsell color system of the United States, the uniform color system of the American Optical Society (sa-os), the German Industrial Standard DN6164 color system, and the natural color of Sweden. System (NCS), etc. The above color systems have their own color theory and application characteristics. At present, the "Chinese Color System Sample Booklet" has been published in our country. It is a color system calibrated according to the theory and compilation principles of the Chinese color system and with reference to the internationally accepted three-dimensional attributes (hue, lightness and chroma). Its national standard number is G5B A26003-94.
