Application of powder materials in different kinds of coatings
1. Application of powder materials in coatings
1) Extender pigments (heavy calcium, light calcium, kaolin, etc.) can improve the “dry hiding power” effect of latex coatings, replacing part of the amount of titanium dioxide used (called contrast ratio or hiding ratio) to reduce manufacturing costs.
2) Application of wollastonite powder in intumescent latex fireproof coating
In fire retardant latex coatings, fire retardants and emulsions are important for fire resistance. Although the proportion of fillers used in fire retardant latex coatings is not large, wollastonite, aluminum hydroxide and hollow microspheres are used as fillers in fire retardant latex coatings to account for 5%, 2% and 4%. Among them, wollastonite plays the role of the skeleton of the coating film, aluminum hydroxide plays the role of flame retardant, smoke suppression and cooling, and the air beads play the role of carbon layer strength.
Kaolin and wollastonite with the same fireproof effect of the carbon layer have high expansion, the highest is wollastonite, followed by kaolin, and the lowest time sequence of talc powder is wollastonite>kaolin>talc powder, which means that when the carbon layer reaches a honeycomb shape, The higher the expansion height, the better the heat insulation and fire protection effect. Of course, the carbon layer should not be too high, otherwise it will cause the separation between the carbon layer and the steel plate, which will not play the role of fire prevention. The coating containing Al(OH)3 has the least amount of smoke, especially the longest fire resistance time, and is a very good flame retardant additive.
The order of comparing the five inorganic fillers is: Al(OH)3 >wollastonite>kaolin>talc>CaCO3, so it is the most ideal to use Al(OH)3 as a flame retardant with wollastonite. In the formula, silica fume Stone 5%, Al(OH)3 2% is the most ideal filler layer, with the longest fire resistance time and the least amount of smoke.
3) Application of sericite (muscovite) in latex paints for exterior walls of buildings
Sericite silicate flakes have a strong extinction shielding function, can absorb more than 80% of ultraviolet rays, close to the ultraviolet absorption rate of titanium dioxide, good wear resistance, insulation, good chemical stability, acid and alkali resistance, Water permeability. When adding 5% to latex paint for exterior walls, it can improve the weather resistance of the coating, delay the chalking, discoloration and cracking of the coating, and increase the hardness and toughness of the coating film. A 600-hour artificial aging test was carried out on the latex coating containing Ca4 wet sericite and the latex coating. The aging performance and appearance have been improved from blistering and peeling to non-foaming peeling and no cracking, and the discoloration has changed from level 2 to level 1. Chalking changes from level 3 to level 0 (no chalking), but sericite is not suitable for the obvious matting effect of high-gloss exterior wall latex paint on the paint.
2. The role of powder materials in coatings
Powder materials for coatings include extender pigments, anti-rust pigments, coloring pigments, special pigments, and functional pigments. Among them, extender pigments are a major branch of the powder particle system. Due to the particle size, particle shape, oil absorption, density characteristics of the extender pigment, or the unique characteristics after modification, it has a certain effect and influence on the coating. Especially ultra-fine powder materials until nano-scale materials have a more obvious effect on coatings, and roughly have the following effects:
1) The hiding power of the pigment can be used efficiently
2) The solid content of the paint can be increased, and the limit of harmful volatile organic compounds (VOC) in the paint can be controlled.
3) It can improve the scrubbing resistance of the coating and control the gloss of the coating
4) It can control the sedimentation of the coating system and increase the tensile strength of the coating film.
5) It can adjust the viscosity of the coating system and improve the adhesion of the coating
6) It can improve the abrasion resistance and slip resistance of the coating
7) When the pigment physique concentration in the coating formulation is less than the critical pigment physique concentration, the dry covering power of the coating film can be improved
8) Can be used as a reinforcement and extender for coatings
9) It can improve the stain resistance and corrosion resistance of the coating.
10) A buffering agent that can control the pH of water-based latex coatings
11) It can improve the hand feel of the coating and the hardness of the coating when it feels wet and dry. Extender pigments are not only used as fillers to reduce the cost of coating manufacturing, but also specially processed extender pigments play a role in improving the performance and function of the coating.
Article source: China Powder Network