1. According to the number of colonies in the production environment, seasonal and climatic conditions, water sources, raw materials and other conditions to properly adjust the amount of addition, the general use of concentration of 5-8 ‰, the actual amount of addition please use microbial test to obtain.
2. 5‰ is recommended for resin, paper, trademark paper, silk flower, wax thread, leather, shellac, shoes, etc.
3. In water-based emulsion paints, acrylic emulsions, acrylic emulsions, polypropylene emulsions, coatings and other products, the recommended addition amount is 8‰.
4. In the system rich in protein, starch, paste, hydroxymethyl cellulose, polyvinyl alcohol and other materials, the recommended addition amount is 10‰, the actual addition amount should be obtained by microbial test.
Stir and heat the light-cured polyester acrylate coating to above 60°C, then add vinyl-containing alkoxysilane, stoichiometric amount of water and catalyst. Under delayed stirring and dispersion, the fumed silica is Adding the mixture, during the dispersion process, the alkoxy-OR on the silane molecule undergoes a condensation reaction with the numerous hydroxyl groups on the surface of the fumed silica particles through hydrolysis. More silane molecules further condense with hydroxyl groups on the surface of the fumed silica, and the silane molecules that have been added form a shell layer of siloxane on the outside of the fumed silica particles. Figure 13-27 is a model reaction of alkoxysilane with vinyl to form a siloxane shell layer on the surface of fumed silica particles. The shell layer covers the uncondensed hydrophilic hydroxyl groups on the surface of the fumed silica particles, and obtains a shell with hydrophobic and organic functional groups outside, which greatly reduces the pyrolysis process of the coating. The association of hydrogen bonds on the surface of silica particles is also compatible with organic resins to obtain a low-viscosity coating system. Figures 13-28 show the model reaction of siloxane shell-coated fumed silica and fumed silica to form a siloxane shell layer.
The vinyl group of the siloxane shell layer in the silane molecules on the shell participates in the free radical polymerization reaction of the polyester acrylic SiOz particle ester during photocuring, so that the inorganic nano-silica becomes a part of the film-forming polymer material , To achieve the purpose of chemical modification. Figure 13-28 Silicone coated Si Oz particles
In the modification process, the introduction of fumed silica under reaction with silane is an important basic part and key of the modification process.
The above-mentioned reaction between the silane and the surface hydroxyl of the fumed silica particles of the aggregate occurs in the polyester acrylate resin, so a certain degree of dissociation of the agglomerates occurs, and the nanoparticles are covered by the siloxane shell. Therefore, the presence of particles is usually not observed, and a large amount of anti-wear agent can be added to obtain a transparent coating film.
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