The two-component is usually added to the polyurethane system in advance in proportion, and the two-component is added to the B-component of the non-polyurethane prepolymer (usually the A-component is the polyurethane prepolymer) and mixed well; it can also be added to the polyurethane material to be used immediately at the construction site and mixed well after mixing quickly.
Calcium carbonate is an important physique anti-rust pigment in fire-resistant coatings and metal anti-rust coatings. It can generate calcium hydroxide Ca(OH)2 due to its hydrolysis, which can form hydrogen bonds with the iron surface to enhance the adhesion of the paint film. It can also absorb H+. Therefore, calcium carbonate is suitable for fire-resistant coatings used in coastal areas. The appropriate amount of heavy calcium polytetrafluoroethylene wax paper carbonate in this type of fire-resistant coatings is 10%.
In various resin fireproof coatings, it is often required to add fine calcium carbonate, active calcium carbonate and heavy fine active calcium carbonate, which play a very important role in the smoothness of the coating and the smoothness of the coating surface in the application. Generally, it is required to activate calcium carbonate in oil-based fire-retardant coatings to transform it from hydrophilic to lipophilic, so as to achieve the effect of homogeneity with oil.
In inorganic fire-retardant coatings, precipitated calcium carbonate is used in Yin with a dosage of 16% to 20%. Using precipitated calcium carbonate (lightweight) is not easy to precipitate. In addition, for inorganic fireproof coatings, water glass (NagO·nSi Og·nH:O) is often added to the coating, and the silica gel in the water glass can be firm The ground coating adheres to the surface of the powdery calcium carbonate particles to form a solid block to make the coating firm. The reaction equation is as follows:
NagO·nSi Oz+CaCO, ——Na, CO, +(n-1) Si 0, +CaSio,
NagO·nSi Og+CO, +mH gO—Na eCO j+nSi Og·mHO
In the latex fire retardant coatings and water-based fire retardant coatings, in order to disperse calcium carbonate, in addition to controlling the crystal form, so that the calcium carbonate particles form a cubic shape of 0.1~1jm, a dispersing agent is also added. Suitable dispersing agents are acrylic copolymers and acrylic esters. Copolymers, methacrylic acid copolymers, maleic anhydride pentene copolymers, etc. Indoor polyvinyl acetate latex fireproof coatings usually use about 10% precipitated calcium carbonate, and polyacrylic acid latex fireproof coatings usually use about 15% precipitated calcium carbonate.
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