The method of 10 photomeometer to test the cover force of redstone titanium white powder was studied.

the method of testing the cover force of redstone titanium dioxide with a 10th d'. Li Haiyan, Wang Yunhua, Wang Lei, Li Baojin, Cui Qingxiong, Longxiang (Yunnan Xinli Nonferrous Metals Co., Ltd., Kunming, Yunnan 650100)Pigment cover is the pigment dispersed in a transparent substrate to make it opaque, completely cover the substrate of the minimum amount of black and white material, representing the pigment can cover the surface of the painted object color ability. With a refractive index of 2.75, the redstone titanium dioxide is the largest of all white pigments, so it has the strongest cover and optical properties and is widely used in coatings, plastics, paper and other fields. As an important indicator to evaluate the optical properties of white pigments in coatings, the position of covering force in industrial applications is very important, so a series of test methods have been developed. The more typical test methods include direct visual testing, interpolation based on different thickness coatings, extraterrion based on Kubelka-Munk equations, comparison methods relative to a reference coating, spectral estimation methods combined with chroma principles, and so on, some of which have become international or national standards. The test method of covering force is still developing and perfecting, although the existing method improves the convenience, precision and application range of the test, but it can not completely solve the test problem of cover force, which needs further study and improvement. National standard GB/T 1706-2006 specified the basic indicators of titanium dioxide and the corresponding testing methods, these indicators only adapt to titanium dioxide production enterprises on the quality control of the production process, can not truly reflect the application performance of titanium dioxide products in different industries, while covering force as an important indicator to evaluate titanium dioxide in the paint industry, the corresponding detection methods are not suitable for production requirements. In this paper, the main application areas of titanium dioxide——— coating industry to optimize the masking force test method, the use of spectro-optical meter instead of reflectivity meter for sample reflectivity determination, the use of accurate color quality control software directly characterise the gold-redstone titanium white powder in the coating system cover force, and analyze the key factors affecting the masking force test, to determine the method applicable to the rapid determination of the matte-type titanium dioxide in the coating.1 1.1 Reagents and Instruments 1.1.1 Reagents The main raw materials and reagents include: YR-802 brand of gold-redstone titanium dioxide powder, Yunnan Xinli Nonferrous Metals Co., Ltd. R-960 brand of gold-redstone titanium white powder, DuPont Corporation of the United States; acrylic varnish, Jiangsu Panhua Chemical Co., Ltd., acrylic resin quality score of 50%;1.1.2 Instruments and Application SoftwareMain equipment and instruments include: SHH-IV oscillation mixer, Zhengzhou Sanhua Technology Industry Co., Ltd., Henan Province; AFA-II. automatic film coater, Shanghai Pushen Chemical Machinery Co., Ltd.; BGD206/3 wet film preparationer, Guangzhou Standard Gerda Experimental Instrument Supplies Co., Ltd., Guangdong Province; BGD1102 Type Cover Force Test Paper, Guangzhou Standard Gerda Experimental Instrument Supplies Co., Ltd.; Glass Grinding Microbeads, Guangzhou Standard Gerda Experimental Instrument Supplies Co., Ltd., Guangdong Province, particle size 2.0 to 2.5 mm; Glass Bottle, Guangzhou Standard Gerda Experimental Instrument Supplies Co., Ltd., Guangdong Province, volume of 50 mL; CM-2600d light-split meter, Koenigsa Micronda Corporation of Japan; BSA8201-CW Electronic Balance, Sedulis Scientific Instruments (Beijing) Co., Ltd.; QXD Scraper Micro meter, Shanghai Modern Environmental Engineering Technology Co., Ltd.precise color quality control (PCQC) software for The Commercial Software developed by Japan's Koenigsa Minota for the company's dlight meters.1.2 Method using the same paint material will be sampled in accordance with a certain formula and method to make lacquer pulp, in the cover force test paper using a wet film preparationer to make the same thickness of the coating film, natural drying, the use of dlight meter on the black and white background samples for determination, through the PCQC software directly to express the masking force of the sample. The specific test method is as follows: 1) lacquer preparation. The 100 g glass grinding microbeads are placed in the glass bottle, the 50 g acrylic (or alkyd) varnish is placed in the bottle, a 12 g titanium white powder sample is added, and the glass bottle containing the material is placed in an oscillating mixer, oscillating grinding 90 min.2) Film preparation. Place the cover force test paper on the automatic film coater, add titanium white powder lacquer to the cover force test paper, use a preparation with a wet film thickness of 100 m to paint the coating film, and place the coating film at room temperature to dry.3) Cover force determination. The white and black backgrounds after coating are measured by 10-photometric meters, and the masking force of the sample is directly indicated by PCQC software.2 Results and discussion of the 2.1 spectro-optical photometric method and the traditional reflectivity method to test the goldstone-type titanium white powder cover force The masking force is expressed by calculating the ratio by the formula,and it is stipulated that when the contrast rate is 98%, the coating film is considered to have been completely covered.the principle of using a 12-photomeometer to test the cover force of the redstone titanium dioxide is based on the traditional reflectivity method. The innovation of this method is to combine the characteristics of spectrographic meter and PCQC software, to obtain the data on the white and black bottoms of the coating film by using a spectrograph similar to the reflectivity meter, to directly characterize the masking capacity of the redstone titanium dioxide pigment through the PCQC software, and to omit the calculation steps in the process of traditional reflectivity measurement, which is conducive to the application of product quality control and detection in the actual process. The spectrometer used in this method is the conventional equipment used by titanium dioxide production enterprises to detect pigment optical index lightness L, blue degree b, etc. , and the method not only saves the traditional reflectivity method test instrument, but also uses PCQC software direct characterization, which replaces the traditional calculation process, so the method is feasible in the actual production process.2.2 pigment volume fraction isthe ratio of the volume of pigment fillers in the coating to the total product of the solid parts used in the formulation. When the pigment volume fraction is small, the distance between the titanium dioxide particles in the coating is large, and when the pigment volume fraction is large, the distance between the titanium dioxide particles in the paint is small and the particle arrangement is crowded. When the distance between particles is less than half wavelength of light waves, a single particle no longer has the function of a separate scattering center, but reduces the masking force. In acrylic varnishes with different pigment volume fractions, the relationship between the redstone titanium white powder cover force and the pigment volume fraction is shown in Figure l. As can be found from the figure, when the pigment volume fraction reaches 16%, the gold-redstone titanium white powder has the greatest cover force in acrylic varnish, and with the increase of pigment volume fraction, the covering force is gradually reduced. Combined with the above analysis, in the coating formula containing only goldstone-type titanium dioxide pigment, the best pigment volume fraction of about 16% can truly reflect the cover force of gold-redstone-type titanium dioxide in the coating, that is, to determine that every 50 g acrylic varnish added 12 g of gold-redstone-type titanium dioxide powder as the best ratio.2.3 Determination of the test paintThe pigment samples with R-960 and YR-802 redstone-type titanium dioxide were made into lacquer slurry in acrylic varnishes and alkic acid varnishes, respectively, with their masking force and blue degree b*test results as shown in Table 1. As can be known from the table, R-960 and YR-802 gold-redstone titanium white powder in the alkalic varnish cover force is greater than acrylic varnish, the main reason is that the alkyl varnish is slightly yellow state, can increase the blackout power of the gold-redstone type titanium white powder in its system, according to the tested b-value can also be derived from the sample of titanium dioxide in the alkylated varnish than acrylic varnish sample yellow. In order to eliminate the interference of yellow paint on the test results, according to the experimental results, for the matte test of the goldstone-type titanium dioxide powder, it is determined that acrylic varnish is preferred as the paint material.. 2.4 Determination of Oscillation Grinding Time The pigment samples of R-960 and YR-802 redstone titanium dioxide were made into lacquer slurry in acrylic varnishes, respectively Sample sampling coating for oscillation grinding of 30, 60, 90, 120 min, pigment cover and scraper fineness test results for oscillation grinding at various stages are shown in Figures 2 and 3. As can be known from Figure 2, the cover force of both the R-960 and YR-802 samples increases with the extended oscillation grinding time and stabilizes when the oscillation grinds 90 min. As can be known from Figure 3, the scraper fineness of the two samples, R-960 and YR-802, decreases with the extended oscillation grinding time and stabilizes when the oscillation grinds 90 min. Combined with the above analysis, in order to make the goldstone-type titanium dioxide in the paint material is completely dispersed, determine the oscillation grinding time of 90 min, the test results can reflect the gold-redstone-type titanium white powder in the paint cover force ability. . 2.5 Determination of the thickness of the coating film with R-960 and YR-802 redstone-type titanium dioxide as pigment samples in acrylic varnish made of lacquer paste, respectively, using a wet film thickness of 75, 100, 120 m of the preparation for the coating, different wet film thickness cover test results as shown in Figure 4. As can be known from the figure, the cover force of the R-960 and YR-802 samples increases with the increase of coating thickness, but stabilizes after reaching a certain degree. In order to overcome the coating is too thin to completely cover the substrate substrate color, but also to truly reflect the gold-redstone titanium dioxide cover capacity, according to the experimental results, determine the appropriate coating wet film thickness of 100 m. 3 Conclusion It is feasible to use spectrograph instead of reflectivity meter to determine the cover force of redstone titanium dioxide in the production practice. The key factors affecting the test method are as follows: 1) the use of acrylic varnish as a sign of the golden redstone type titanium white powder cover, 2) to determine the ratio of goldstone type titanium white powder pigment to the paint, pigment volume score of 16%, that is, 50 g acrylic varnish need to add 12 g goldstone titanium white powder; 3) Oscillation grinding time of 90 min allows the redstone titanium white powder to be completely dispersed in the paint, 4) coating wet film thickness of 100 m can completely cover the substrate's base color.
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