Can baking change the hardness of silicone?


2020/9/22 9:33:14



What is silica gel hardness? In the silicone industry, the unit to measure the softness of silica gel is called silica gel hardness. The unit of silica gel hardness is Shao A hardness, and also has Shao C hardness. General liquid silica gel in the curing process, the hardness of silica gel will slowly rise, until reaching the peak. So how do you measure the hardness of silicone? The hardness of the liquid silica gel mold is in Shaw A as A unit, from 0 to 50 degrees. The softest hardness is Shaw A zero, and the hardest can reach Shaw A 50 degrees, with one unit every five degrees in the middle. According to this law, the silica gel hardness increases or decreases successively. So the user has a question, why is the hardness of the silicone we bought last time different from the hardness we bought this time, a deviation of 2 degrees? This is because silica gel belongs to chemical raw materials, and there will be errors in the production process of chemical raw materials, but such errors are within a reasonable range. Within this reasonable hardness error range, the operation and use of silica gel will not be affected.


So how do you change the hardness of the silicone? When users feel that the hardness of silica gel is too hard, the hardness of silica gel can be adjusted by adding silicone oil. For every 2% of dimethyl silicone oil added, the hardness decreases by one degree. If the hardness of silica gel is too soft, how to adjust the hardness? You can choose to add silicone oil containing hydrogen in proportion.


But there's an online claim that baking at high temperatures can change the hardness of silicone, and that's not entirely true. When the liquid silica gel is added with curing agent in proportion in the liquid state, after high temperature baking, the silica gel will slowly thicken, and the hardness of the silica gel will gradually increase. Molding liquid silica gel is generally after 100-200 degrees of high temperature baking, curing in about 10-15 minutes. Condensed silica gel will not solidify quickly in a short time after baking at high temperature. When the silica gel has been cured, however, continue to work under high temperature baking, will accelerate the aging of silica gel, so that the hardness of the silicone can present the rise of illusion, the performance of the silica gel will also accelerate the crisp, tensile strength decreased, tensile strength, elongation decreased, this is the silica gel after continuous high temperature, the process of aging.




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