1． Firstly,clean the mold with detergent, and dry up the mold by a piece of cloth or an air gun and then coat the mold with a layer of release agent.
2. The normal proportion between the pad printing silicon and the silicone oil depends on the requirements of the customers. If pattern with big area to be printed, a soft silicon pad is needed and the amount of silicone oil is increased. Contrarily, if a silicon pad with high hardness is needed, the silicone oil should be added less or not . The hardness of general pad printing silicone rubber is approximate of 15A°~-25 A°; if too much silicone oil is added, the silicon pad is so soft that the printing times is limited, the molecular weight of the silicon will be damaged by the silicone oil no matter how superior quality the silicon is, thereby bringing about abrasion intolerance, solvent intolerance and ageing.
3. General mixing proportion is as follows: add 30g silicone oil into 100g silicon with the hardness of the silicon pad being 20A°, which is suitable for the pad printing for alloy car and products with small patterns and contact areas. If a big pressure contact surface or a soft silicon pad is needed, the mixing proportion between the silicon and the silicone oil can be 100:30-100:50. But please note that the more amount of silicone oil added, the softer the silicon pad, which will reduce times of pad printing, abrasion resistance and solvent resistance. In addition, the times of pad printing will be correspondingly reduced which will cause increased cost and material waste.
4. The amount of the curing agent and the chemical reaction with the silicon is as follows: mix 100g silicon and 50g silicone oil sufficiently and evenly, then add the curing agent which is 2%-3% of the total weight of the silicon and the silicone oil, mixing for 2-3 minutes, and then deair to remove the air bubbles . The time of deairring generally does not exceed 10 minutes. If the deairing time is too long,it may cause fast curing of the silicon and impact the quality of silicon.
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