When we use tin-curing mold silicone as raw material to make silicone molds, sometimes we feel that the default operation time and curing time do not meet our own process requirements, which can actually meet our needs by regulating the ratio of silicone to curing agent. The following to explain the different proportions of silicone and curing agent corresponding to the operating time and curing time for your reference.
First of all, let's understand the characteristics of tin-cured silicone, its operation time and curing time are interrelated, the longer the operation time the longer the curing time, the shorter the operation time the shorter the curing time. Of course, the process time is also related to the temperature, the higher the temperature curing faster, and vice versa, the slower, generally when below 0 ° C is difficult to activate the activity of the curing agent, liquid silicone raw materials will be very difficult to cure.
Secondly, after excluding the influence of the external environment, is the influence of the silicone raw materials themselves, the current market tin-curing silicone AB ratio is usually 100:2 to 100:4, for some of the higher requirements in the use of the proportion can also increase the range, without affecting the curing of silicone raw materials and performance of the premise, AB ratio range can be adjusted between 1% to 5% range. Less than 1% will be difficult to cure, and higher than 5% will affect the resistance of silicone Tear and tensile properties.
At a temperature of 23°C to 25°C degrees, some of the data are as follows.
| AB Ratio (Weight Ratios) | Operating Time (Minute) | Curing Time (Hour) |
|---|---|---|
| 100:1 | 50-60 | 14±2 |
| 100:2 | 40-50 | 12±2 |
| 100:3 | 30-40 | 10±2 |
| 100:4 | 20-30 | 8±2 |
| 100:5 | 10-20 | 6±2 |
Conclusion: The ratio of silica gel to curing agent should be at least 1% and at most not more than 5%, generally 2% to 3% at 20-30℃ temperature is the most suitable ratio.