Influence of formula composition of real stone paint on temperature-changing color difference

Real stone paint is mainly composed of emulsion, colored sand, additives (film-forming aids, thickeners, etc.), so this article discusses the influence of real stone paint formula on temperature-changing color difference from these aspects.

Experimental method: In the experiment, each formula is made of liver red colored sand to make real stone paint, and a film-making template with a thickness of 1mm is scraped to make a film. The relative humidity is 50%, and the temperature is 5, 10, 23, and 35°C. After curing for 7 days, visually compare the color of the dry film and score it on a scale of 0-10 (the color of the real stone paint film is not uniform, it is not suitable to use a Spectrophotometer to measure and score), 10 points are the darkest color, 0 points are the lightest color , the higher the score, the better the film quality, and the lower the score, the worse the film quality. The closer the final score of real stone paint with the same formula is maintained at different temperatures, the smaller the temperature color difference and the better the performance.

lotion

From the above analysis of the reasons for the temperature change and color difference of real stone paint, it can be seen that the amount of emulsion has a great influence on the porosity of the paint film, which may lead to temperature change and color difference. Table 1 is the paint film color rating of four kinds of real stone paints with 8%, 10%, 12% and 15% of emulsion at different temperatures.

 Summarizing the scoring data in Table 1, we can see the following rules:

1. The higher the emulsion content, the darker the color of the real stone paint and the smaller the temperature-changing color difference; on the contrary, the lower the emulsion content, the lighter the color of the real stone paint and the larger the temperature-changing color difference;

2. For the same formula, the higher the temperature, the darker the color, and the lower the temperature, the lighter the color;

3. The color difference of real stone paint with different emulsion content is relatively small during high temperature curing, but the color difference is relatively large during low temperature curing.

colored sand

Colored sand is another important component of real stone paint besides emulsion, and its impact on the cost and performance of real stone paint is second only to emulsion. The fineness, water absorption, hardness, etc. of colored sand may have an impact on temperature-changing color difference. Table 2 shows the color evaluation results of four kinds of real stone paints with different colored sand gradations at different temperatures.

Analysis of the scores in Table 2 shows that the finer the colored sand is at the same amount of emulsion, the lighter the color at the same temperature, and the greater the temperature-changing color difference at different temperatures. Comparing formulas 2 and 6, it can be seen that when the gradation of sand is the same, color change due to temperature difference is more likely to occur when coloring with color paste.

Comparing the data in Table 1 and Table 2, it can be seen that the fineness of colored sand may have a greater impact on thermal color difference, because the fineness of colored sand not only affects the porosity but also the size of the pores, and finally improves the light scattering efficiency from two aspects And produce stronger temperature change color difference.

In recent years, due to vicious competition, in order to reduce costs and reduce the amount of high-priced colored sand used in real stone paint, a small number of companies often use fine colored sand (such as 200 mesh colored sand) or even color paste for color matching, which leads to temperature changes. One of the main reasons for frequent chromatic aberration problems. High-quality real stone paint should use 40-80 mesh and 80-120 mesh colored sand for color mixing. If necessary, when using finer colored sand for color mixing, the amount of emulsion should be increased accordingly to reduce temperature change occurrence of chromatic aberration.

For the same reason, the water absorption and hardness of the colored sand used for real stone paint are also very important indicators, which need to be strictly controlled. The high water absorption rate of colored sand is often due to the large amount of fine ash, which will directly lead to the increase of porosity and the temperature-changing color difference. Colored sand with low hardness usually has a high water absorption rate and may be further crushed and pulverized due to grinding during the production process, which increases the possibility of temperature-changing color difference.

Sintered colored sand and dyed colored sand can reduce the consumption of emulsion to a certain extent due to the low ash content and low water absorption rate, so the occurrence of temperature and color difference can be reduced.