In a one-component room temperature vulcanized silicone sealant system, each component has a crucial impact on performance: the relative molecules of the base polymer The quality will affect the fluidity, process operability and adhesion performance of the sealant; the functional group and functionality of the cross-linking agent will affect the adhesion and cross-linking speed of the sealant; the type and amount of filler will affect the strength, Process operability and thixotropy; catalysts will affect the vulcanization speed and storage stability of the sealant.
As a tackifier, a very small amount of silane coupling agent can significantly improve the adhesion of the sealant to the substrate, but for different For the base material, it is still necessary to choose the appropriate type of silane coupling agent to achieve the expected bonding effect. Kain Chemical studied the effect of two silane coupling agents, KH-560 and KH-792, on the performance of one-component room temperature vulcanized silicone sealant.
Preparation of one-component room temperature vulcanized silicone sealant
Add a certain amount of 107 glue, dimethyl silicone oil and calcium carbonate into a high-speed mixing mixer, heat to 100~130 ℃, vacuum and stir for 120 minutes, remove Moisture in the filler; after the base rubber is cooled to room temperature, add cross-linking agent, chain extender, catalyst and coupling agent in different proportions in sequence (Table 1), and stir evenly under vacuum to obtain a single-component room temperature Vulcanized silicone sealant.
The effect of silane coupling agent ratio on the bonding properties of sealants
Prepare different silane coupling agents, and examine the bonding performance of the obtained one-component room temperature vulcanized silicone sealant to uncoated, colorless, transparent float glass and anodized aluminum Impact. No matter what coupling agent ratio is used, the one-component room temperature vulcanized silicone sealant has little effect on the adhesion of the glass, and the failure mode of the sample is 100% cohesive failure.
When the dosage of KH-560 is not less than KH-792, the one-component room temperature vulcanized silicone sealant has poor adhesion to anodized aluminum and may cause damage. The form is mixed failure; as the amount of KH-792 increases, the adhesion of the one-component room temperature vulcanized silicone sealant to anodized aluminum increases, and the failure form changes to 100% cohesive failure. When choosing aluminum as the base material, the one-component room temperature vulcanized silicone sealant with high KH-792 content has better bonding effect.
Effect of silane coupling agent ratio on tensile modulus of sealant
As the dosage of KH-792 increases, the tensile modulus of the one-component room temperature vulcanized silicone sealant first increases and then levels off. When the proportion of KH-792 exceeds 66.7%, the tensile modulus tends to be stable.
The effect of silane coupling agent ratio on the elongation at break of the sealant. As the amount of KH-792 increases, the elongation at break of the sealant gradually increases. big.
The proportion of silane coupling agents in the one-component room temperature vulcanized silicone sealant system is small, but it plays an important role in the various properties of the sealant. This article compares the effects of silane coupling agents KH-560 and KH-792 on the bonding properties,tensile modulus and elongation at break of one-component room temperature vulcanized silicone sealant. The results show:
1. For float glass, silane coupling agents with different ratios of KH-792 and KH-560 have little effect on the bonding performance of the sealant; Anodized aluminum, KH-792 can effectively improve the bonding performance of the sealant when the dosage is increased.
2. The ratio of KH-792 and KH-560 has a greater impact on the mechanical properties of the sealant. As the amount of KH-792 increases, the sealant’s The elongation at break gradually increases, while the tensile modulus shows a trend of increasing first and then leveling off.
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