The main methods for using silane coupling agents are surface pretreatment and direct addition. The former involves treating the surface of fillers with diluted coupling agents, while the latter involves adding the original coupling agent solution during resin and filler pre mixing.
The solution of silane coupling agent is conducive to the dispersion of silane coupling agent on the surface of materials. The solvent is a solution prepared by water and alcohol. The solution is generally silane (20%), alcohol (72%), water (8%), and alcohol is generally ethanol (para ethoxysilane), methanol (para methoxysilane), and isopropanol (for silane that is not easily soluble in ethanol or methanol). Due to the fact that the hydrolysis rate of silane is related to the pH value, neutral is the slowest, and acid and alkali are relatively fast. Therefore, it is generally necessary to adjust the pH value of the solution. Except for aminosilane, a small amount of acetic acid can be added to other silanes to adjust the pH value to 4-5. Aminosilane is alkaline and does not need to be adjusted. Due to the hydrolysis of silane, it cannot be stored for a long time and is best prepared and used immediately, preferably within one hour.
Here are some specific applications for users' reference:
1. Pre treatment filling method: Place the filling material into a solid mixer (such as a high-speed solid mixer HENSHEL or V-shaped solid mixer), and directly spray the silane solution onto the filling material and stir. The higher the speed, the better the dispersion effect. Generally, the stirring time is 10-30 minutes (the slower the speed, the longer the time), and the filler should be dried at 120 degrees Celsius (2 hours) after treatment.
2. Silane coupling agent aqueous solution (glass fiber surface treatment agent): Glass fiber surface treatment agents often contain film-forming agents, antistatic agents, surfactants, coupling agents, and water. The dosage of coupling agent is generally 0.3-2% of the total amount of glass fiber surface treatment agent. First, adjust the pH value of the 5-fold aqueous solution to a certain value with organic acid or salt. With sufficient stirring, add silane until transparent, and then add the remaining components. For insoluble silane, isopropanol can be used as a solubilizer. During the drawing process, spray the glass fiber surface treatment agent onto the glass fiber and dry it to remove the solvent and moisture.
3. Bottom method: Prepare a solution of 5% -20% silane coupling agent as described above, and treat the substrate surface by coating, brushing, spraying, and impregnating. Remove and air dry at room temperature for 24 hours, preferably at 120 ℃ for 15 minutes.
