Application and research progress of inorder fillers in the coatings industry (2)

in the frame-shaped silicon-oxygen skeleton, the silicon-oxygen tetums share four corner tops with each other, forming a skeleton that develops into three-dimensional space. However, this kind of frame structure is not completely composed of silicon oxygen tidal body, but is partially replaced by aluminum oxygen tidal body, so there is an excess negative charge to form a shelf-like vion. Longstone powder is a mineral filler with a typical frame-like structure. According to the difference of cation, long stone powder mainly exists in three forms: sodium long stone, potassium long stone and calcium long stone. The long stone powder shape is shown in Figure 2, is composed of angular nodule particles, compared to spherical or ordinary block fillers, can form a more dense coating film, giving the coating film high wear resistance and scratchability, improve the corrosion resistance of the coating film. Xia Changshi is composed of sodium long stone, potassium long stone and xia stone. Xiashi is nominally aluminum silicate sodium, but potassium replaces some of the sodium. Xia Changshi is a six-yuan ring made up of silicon-oxygen tetular ring angles. Half of the tectome's Si4 plus is replaced by Al3 plus, resulting in an imbalance in charge compensated by Na and K. Unlike longstone powder, Na-plus can be exchanged with H-plus, which reduces the acid stability of xiashi.when silicon-oxygen tetomes share two axle tops with each other, they form a one-way extended needle-shaped or fibrous silicon-oxygen skeleton, such as silica ash, whose shape is shown in Figure 3. The chemical composition of silicate is calcium silicate, which is 13 to 15 times the length of diameter. Silica ash can increase the bright color of the white coating, without reducing the whiteness of the coating and cover force, can replace part of the titanium white powder. Silica ash can also improve the leveling of coatings, but also as a good suspension of coatings. Silica ash is used in primers to provide corrosion resistance and improve scratch and crack resistance.1.3 Silicon dioxide
Silicon Dioxide (SiO2) is also widely used in nature and can be divided into natural and artificial categories. Natural products include crystalline silicon dioxide, or quartz sand, which is mainly used in the preparation of real stone paint in buildings. There are also non-stereotyped natural silica, i.e. diatom soil, due to its low density and porous properties, commonly used in the inner wall coating to absorb and eliminate odors. In addition, diatom soil has an ion effect, water molecules can be broken down into positive and negative ions, resulting in strong oxidation, play a certain bactericidal effect. Artificial products include precipitated silica and synthetic gas phase silica. Precipitated silica is evenly dispersed in the coating film to produce a slightly rough surface, so that the light diffuse reflection and has a strong anti-lighting effect. Synthesized gas phase silica, also known as white carbon black, has a thickening effect, in the paint shows a certain tentacle. In water-based acrylic systems, the introduction of silicon dioxide may reduce the aging resistance of the coating film. This is because the metal ion impurities contained in silica can causes photooxidation degradation of the coating film under ultraviolet light exposure, and the silicon alcohol-based group in the silicon dioxide pore also promotes photodegradation..