Silane coupling agent use method


1, surface pretreatment


The silane coupling agent is formulated into a dilute solution having a concentration of 0.5 to 1%. When used, it is only necessary to apply a thin layer on the cleaned surface to be adhered, and after drying, the glue can be applied. Most of the solvents used are water, alcohol (methanol for methoxysilane, ethanol for ethoxysilane), or a mixture of hydroalcohol, and water with no fluoride ion and inexpensive non-toxic ethanol or isopropanol. In addition to the aminoalkyl silane, the solution prepared by the other silane coupling agent needs to be added with acetic acid as a hydrolysis catalyst, and the pH is adjusted to 3.5 to 5.5. Long-chain alkyl groups and phenyl silanes are not suitable for use as aqueous solutions because of their poor stability. After silane hydrolysis, it can not be stored for a long time. It is best to use it now. It is best to use it within one hour.


2, directly add


The silane coupling agent is directly added to the adhesive component, and is usually added in an amount of from 1 to 5% by weight based on the amount of the base resin. After the glue is applied, depending on the diffusion of the molecules, the coupling agent molecules migrate to the bonding interface to produce a coupling effect. For the adhesive that needs to be cured, it needs to be placed for a period of time after the glue is applied to cure, so that the coupling agent can complete the migration process, and good results can be obtained. In practical use, the coupling agent often forms a deposited layer on the surface, but only the monolayer is really effective, so the amount of the coupling agent need not be excessive.


Specific use method of silane coupling agent


1. Pretreatment filler method


The filler is placed in a solid mixer (high-speed solid mixer HENSHEL or a V-type solid mixer, etc.), and the above silane solution is directly sprayed on the filler and stirred, and the higher the rotation speed, the better the dispersion effect. Generally, stir for 10-30 minutes (the slower the speed, the longer the time), and the filler should be dried at 120 °C (2 hours).


2. Silane coupling agent aqueous solution


(glass fiber surface treatment agent): The glass fiber surface treatment agent often contains: a film former, an antistatic agent, a surfactant, a coupling agent, and water. The amount of the coupling agent is generally 0.3% to 2% of the total amount of the surface treatment agent of the glass fiber. The pH value of the 5 times aqueous solution is first adjusted to a certain value with an organic acid or a salt, and the silane is added until it is transparent under sufficient stirring. The remaining components are then added, and for poorly soluble silanes, isopropanol can be used to aid dissolution. In the drawing process, the glass fiber surface treatment agent is sprayed on the glass fiber to be dried, and the solvent and water are removed.


3, the bottom method


A solution of 5% to 20% of the silane coupling agent is treated with the above, and the surface of the substrate is treated by coating, brushing, spraying, and taken out at room temperature for 24 hours, preferably at 120 ° C for 15 minutes.


4, direct addition method


The 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 the coupling agent is generally from 0.1% to 2% by weight of the filler (depending on the diameter of the filler). The silane-added resin/filler is then molded (extruded, compression molded, coated, etc.).