Release Date：2017-10-09
With the continuous improvement of industrial production technology, the requirements for materials are becoming more and more strict, especially for fine chemical silicone materials, and silane coupling agent is an important one of them, it is even more indispensable. Therefore, in order to adapt to the needs of industrial production, scientific researchers have continuously researched new varieties of silicone coupling agents.
In the previous article, Dongguan Jianmeng Silicone Editor explained in detail several new silane coupling agent varieties, and I must have a certain understanding of this. However, the problem is coming, just knowing these is not enough, we need to know how to use it, in order to make more reasonable use of silane coupling agent. Therefore, today Jianmeng Chemical will discuss with you how to use organosilane coupling agents.
The silane coupling agent is directly added to the adhesive component, generally the amount is 1 to 5 percent of the amount of the matrix resin. After the glue is applied, the coupling agent molecules migrate to the bonding interface to generate coupling due to the diffusion of molecules effect. For adhesives that need to be cured, they need to be placed for a period of time after being glued and then cured, so that the coupling agent can complete the migration process to obtain better results. In actual use, the coupling agent often forms a deposited layer on the surface, but the function is only a monomolecular layer, so the amount of coupling agent need not be excessive. The use methods of silane coupling agent mainly include surface pretreatment method and direct addition method, the former is to treat the surface of the filler with diluted coupling agent, the latter is to add the stock solution of coupling agent when the resin and filler are premixed. The silane coupling agent is formulated into a solution, which is conducive to the dispersion of the silane coupling agent on the surface of the material. The solvent is a solution prepared by water and alcohol. The solution is generally silane (20%), alcohol (72%), water (8%), the alcohol is generally ethanol (p-ethoxysilane), methanol (p-methoxysilane) and isopropanol (for silanes that are not easily soluble in ethanol and methanol). Because the rate of silane hydrolysis is related to the pH value, Neutral slow, acidic and alkaline are relatively fast, so generally need to adjust the PH value of the solution.
Silane can also be added directly to the filler/resin mixture. When the resin and filler are mixed, the silane can be sprayed directly into the mixture. The amount of coupling agent is generally 0.1~2% of the amount of filler (depending on the diameter of the filler). The silane-added resin/filler is then molded (extrusion, compression molding, coating, etc.).
The silane coupling agent is formulated into a dilute solution with a concentration of 0.5 to 1 percent. When used, only a thin layer needs to be coated on the clean adhered surface, and the glue can be applied after drying. The solvent used is mostly water, alcohol, or a mixture of water and alcohol, and water containing no fluoride ion and inexpensive, non-toxic ethanol and isopropanol are suitable. In addition to aminohydrocarbyl silanes, solutions prepared from other silane coupling agents need to add acetic acid as a hydrolysis catalyst and adjust the pH to 3.5-5.5. Long-chain alkyl and phenyl silanes are not suitable for formulation due to their poor stability Use in aqueous solution. The hydrolysis process of chlorosilane and ethoxysilane is accompanied by severe condensation reaction, and it is not suitable to be used as an aqueous solution or hydroalcoholic solution, but as an alcohol solution. For poorly water-soluble silane coupling agents, non-ionic surfactants with a percentage of 0.1 to 0.2 (mass fraction) can be added first, and then processed into aqueous emulsion by adding water.
5-20% of the silane coupling agent solution is the same as described above, the surface of the substrate is dipped by painting, brushing, spraying, taken out at room temperature and dried for 24 hours, and baked at 120 ℃ for 15 minutes.