To solve the effect of diluent on the viscosity and mechanical properties of silicone, we can start from controlling the amount of diluent, selecting appropriate diluent, standardizing the dilution process, communicating with manufacturers to adjust the formula, etc. The following is a specific analysis:
Control the amount of diluent: When adding diluent, the amount must be strictly controlled. Excessive addition will have an adverse effect on the characteristics of silicone, resulting in performance degradation. It is generally recommended to control the diluent and addition amount within 10%. For example, when adding silicone oil as a diluent, for every 2% of silicone oil added, the hardness of liquid silicone after curing will be reduced by 1 degree, and the tear resistance and tensile strength will also be reduced accordingly.
Choose a suitable diluent:
A dedicated diluent must be used, and water or other acidic and alkaline diluents cannot be used, otherwise the liquid silicone will not be cured and will be scrapped.
Understand the characteristics of different types of diluents (such as inactive diluents and active diluents) and choose according to the type of silicone and application requirements. Inactive diluent molecules do not contain active groups and do not participate in the reaction during the dilution process. They are only blended into the resin and have the purpose of reducing viscosity, but they have an impact on mechanical properties, heat deformation temperature, medium resistance and aging damage. Active diluent molecules contain active groups and must participate in the reaction during the dilution of the adhesive. They can also play a toughening role and are mostly used in epoxy adhesives.
Standardized dilution process:
Standardize the operation during the dilution process to ensure that the diluted liquid silicone standard is unified, avoid product instability, and uneven products.
Considering the evaporation rate of the solvent, if the evaporation rate is too fast, the surface of the adhesive layer is easy to form a film, which hinders the escape of the solvent inside the adhesive layer and causes bubbles in the adhesive layer; if the evaporation rate is too slow, the solvent will remain in the adhesive layer, which will affect the bonding strength. Usually, several solvents with different boiling points are mixed to adjust the evaporation rate.
Communicate with the manufacturer to adjust the formula: When silicone with specific viscosity and performance is needed, you can communicate with the manufacturer. The manufacturer will achieve the effect of reducing the viscosity of liquid silicone by adjusting the raw materials of silicone and different formulas of raw materials. This operation minimizes the impact on the physical properties of the product, thereby ensuring the stability of the product.