The fineness of the paint is achieved by stirring high-speed dispersion and sand mill grinding to make the pigment and filler particles reach the particle size required by the process. The fineness directly reflects whether the apparent state of the coating film is smooth and smooth. When the fineness is abnormal, the appearance of the coating film will show many large and small particles, the surface is rough and uneven, and there is no luster. These protruding particles are very easy to fall off from the coating film, forming tiny micropores on the surface, and even exposing the underlying substrate, forming many corrosion points, reducing its weather resistance, and seriously affecting the physical and chemical properties of the coating.
Test Instruments
QXD-50 , QXD-100 , QXD-150 scraper Fineness Meter: Shanghai Modern Environmental Engineering Technology Co., Ltd. (see Table 1 for technical specifications), adjusting knife, 200 mesh, 300 mesh metal filter screen.
experiment method
According to ISO 1524, ASTM-D 1210 international standards, fineness (Method A) is judged by using a spatula to take an appropriate amount of paint in the groove of the fineness plate, and use a scraper perpendicular to the fineness plate to pull down at a uniform speed to form a wet film , immediately observe the distribution of particles, the line of sight and the groove surface form an angle of 15 ~ 30°, the initial density is the fineness of the coating, especially in the 3 mm wide strip across the groove contains 5 ~ 10 The position of the particle is accurate to the minimum division value. If individual grains are exposed on other scales, there should be no more than 3 grains within the range between the reading and the adjacent scale line. When the viscosity of the paint is relatively viscous, appropriate amount of thinner can be added to dilute it for easy judgment. Fineness (B method) is to observe the dense scratches left by large particles.
Table 1 Technical indicators of QXD scraper Fineness Meter
According to different fineness requirements, it is necessary to select a Fineness Meter with a different range. When the fineness is below 30 and 30 μm, a Fineness Meter with a maximum value of 50 μm should be selected, and a Fineness Meter with a range of 100 μm should be selected for a fineness of 31~70 μm , when scraping the fineness above 70 μm, a Fineness Meter with a range of 150 μm should be used.
For more details, please refer to the full text of "Discussion on the Treatment of Abnormal Coating Fineness" (Wang Fei)
