1. Surface pretreatment
Prepare a dilute solution of 0.5-1% concentration of silane coupling agent, and apply a thin layer on the clean surface to be adhered. After drying, the adhesive can be applied. The solvents used are mostly water, alcohol (methanol for methoxysilane and ethanol for ethoxysilane), or a mixture of water and alcohol, with water free of fluoride ions and inexpensive and non-toxic ethanol and isopropanol being preferred. Except for aminoalkylsilane, solutions prepared with other silane coupling agents 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. 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.
2. Add directly
Directly add silane coupling agent to the adhesive component, usually in an amount of 1-5% of the base resin. After gluing, the coupling agent molecules migrate to the bonding interface through molecular diffusion, resulting in coupling action. For adhesives that need to be cured, they need to be left for a period of time after coating to allow the coupling agent to complete the migration process and achieve better results. In practical use, coupling agents often form a deposition layer on the surface, but only the single molecular layer actually works, so the amount of coupling agent used does not need to be too much.
Specific usage method of silane coupling agent:
1. Pre treated packing method
Place the filler into a solid mixer (such as a high-speed solid mixer HENSHEL or V-shaped solid mixer), and spray the silane solution directly onto the filler and stir. The higher the speed, the better the dispersion effect. Usually stirred at 10&-30 minutes (the slower the speed, the longer the time), after filling treatment, it should be dried at 120 degrees Celsius (2 hours).
2. Silane coupling agent aqueous solution
(Fiberglass surface treatment agent): Fiberglass surface treatment agents often contain film-forming agents, anti-static agents, surfactants, coupling agents, and water. The dosage of coupling agent is generally 0.3% of the total amount of glass fiber surface treatment agent—2%， First, adjust the pH value of the 5-fold aqueous solution to a certain value using organic acid or salt. With thorough 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
Take 5%&A solution of 20% silane coupling agent, as described above, is applied, brushed, sprayed, and impregnated to treat the surface of the substrate. It is then taken out and dried at room temperature for 24 hours, preferably baked at 120 ℃ for 15 minutes.
4. Direct joining method
Silane can also be directly added to the mixture of fillers and resins. When the resin and fillers are mixed, silane can be sprayed directly into the mixture. The amount of coupling agent is generally 0.1% of the amount of filler used—2%， (determined by the diameter size of the filler). Then, the resin and filler with added silane are molded (extruded, pressure molded, coated, etc.).
