The solvents used are mostly water, alcohol, or a mixture of water and alcohol, and it is advisable to use water without fluoride ions and inexpensive and non-toxic ethanol and isopropanol. Except for aminoalkylsilane, solutions prepared from other silanes require the addition of acetic acid as a hydrolysis catalyst and the adjustment of pH to 3.5-5.5. Long chain alkyl and phenylsilane are not suitable for use as aqueous solutions due to their poor stability. During the hydrolysis process of chlorosilane and acetoxysilane, there will be severe condensation reactions, and they are not suitable for use as aqueous solutions or water alcohol solutions. For silane coupling agent with poor water solubility, 0.1% -0.2% (mass fraction) of non-ionic surfactant can be added first, and then water can be added to process it into water lotion for use.
In order to improve the economic benefits of hydrolysis stability of the product, a certain proportion of non carbon functional silane can also be added to the silane coupling agent. When dealing with difficult to stick materials, mixed silane coupling agents or carbon functional siloxanes can be used in combination. After the treatment solution is prepared, it can be treated by dipping, spray or brushing. Generally speaking, block materials, granular materials, and glass fibers are often treated by impregnation method; Powder materials are mostly treated by spray method; If the surface of the substrate needs to be coated as a whole, the brush coating method is used for treatment.
The process of treating silane coupling agent with alcohol water solution is simple. Firstly, an alcohol water solution is prepared by mixing 95% EtOH and 5% H2O, and adding AcOH to adjust the pH to 4.5-5.5. Stir and add silane coupling agent to achieve a concentration of 2%. After 5 minutes of hydrolysis, a hydrolysate containing Si OH is generated. When using it to process glass plates, it can be immersed for 1-2 minutes with slight agitation, taken out and rinsed twice in EtOH, dried, and then transferred to a drying oven at 110 ℃ for 5-10 minutes, or dried at room temperature and relative humidity<60% 24="" for="" hours="" to="" obtain="" the="" product.="">
If using an aminoalkylsilane coupling agent, there is no need to add HOAc. However, the alcohol water solution treatment method is not suitable for chlorosilane type coupling agents, which will undergo polymerization reactions in alcohol water solutions. When treated with a 2% concentration of trifunctional silane coupling agent solution, coatings with a thickness of 3-8 molecules are mostly obtained.
