关于二氧化钛应用技术的第二节课.ppt

衢州市东太新材料有限公司 * 衢州市东太新材料有限公司 * 衢州市东太新材料有限公司 * 衢州市东太新材料有限公司 * 衢州市东太新材料有限公司 * 衢州市东太新材料有限公司 * 衢州市东太新材料有限公司 * 衢州市东太新材料有限公司 * The first step during the grinding process of a pigment is the wetting of the pigment agglomerates by the liquid phase. Air and humidity on the pigment surface are replaced by the binder solution. In the dispersion step the agglomerates are then broken down by mechanical forces. In the third step the pigment dispersion has to be stabilized in order to avoid re-flocculation of the system. Additives can be very helpful in the first and in the last step. Wetting additives reduce the interfacial tension between the pigment particles and the binder solution and thus improve the wetting process. Dispersing additives keep the pigment pasrticles separated from each other and thus avoid flocculation. 衢州市东太新材料有限公司 * 衢州市东太新材料有限公司 * 衢州市东太新材料有限公司 * 衢州市东太新材料有限公司 * Grinding gauge: An experienced lab person can judge fineness in the range of a few micron. The particle size of most pigments is far below 1 μm. Accordingly it is not possible to judge the quality of a pigment dispersion with a grinding gauge. White reduction: The pigment grind to be evaluated is mixed with a white standard and the color development is judged (visually or by measurement). The more intense/darker the color, the better the pigment dispersion. This test method can only be used, if a completely flood and float-free system is guaranteed. This is almost always not the case. 衢州市东太新材料有限公司 * Grinding gauge: An experienced lab person can judge fineness in the range of a few micron. The particle size of most pigments is far below 1 μm. Accordingly it is not possible to judge the quality of a pigment dispersion with a grinding gauge. White reduction: The pigment grind to be evaluated is mixed with a white standard and the color development is judged (visually or by measurement). The more intense/darker the color, the better the pigment dispersion. This test method can only be used, if a comple