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Reasons and solutions for the structure of silicone tube
Silicone tube production process is a natural rubber processing, according to demand formulation -- in a mixing machine mixing, parked about 24h) -- back mixing -- making semi-finished products - vulcanization, trimming, inspection. But the rubber will encounter this problem, structured silica gel. The reason and control method of the structure of the silicone rubber tube is analyzed in the following.
Silica gel structure is refers to the use of white carbon black fill strong silicon rubber material storage put process becomes hard, reduce the plasticity, thereby gradually losing processing performance. This phenomenon called "structured" effect. Have been structured silicone rubber need re after mixing or heat treatment can eliminate this phenomenon and process cost increase.
Causes structural phenomenon: an argument is a silica particle surface silanol activity at room temperature and rubber molecules at the end of the silanol condensation, which leads to the glue hardens, reduce plasticity; another argument is due to the silica surface silanol groups and rubber molecules Si-O bond or end of Si OH radicals generated hydrogen bond, and chemical combination make linear polysiloxane change false crosslinking or micro crosslinking of semi elastic state solid structure, and glue hardens, plasticity is greatly reduced.
There are two methods to control the production of silicone rubber hose:
One, is to join the "structural control agent", with active groups of silicone oil or silane, silicone resin, etc., which is the most commonly used method of production. Such as adding a certain amount of hydroxyl silicone oil, silazane and so on, can play a very good structured control effect; the mechanism with active groups of silicone oil and other substances, and the silica surface active hydroxyl condensation reaction occurs, thus preventing the interaction between silica and rubber.
Second, white carbon black surface treatment, such as the use of silane coupling agent, six methyl silicon nitrogen alkyl silica processing, but also can prevent the silicone rubber structured. The mechanism is coupling agent or silazane and has white carbon black surface parcel (between the reaction and hydrogen bonding combined), white carbon black surface active groups has shield to prevent the interaction between silica and rubber.
In short, the white carbon black of surface treatment or addition agent to control structure, while adding hydroxyl silicone oil on performance should have certain effect. Structured is a slow and the formation of hydrogen bonding process, the key lies in how to control the hydrogen bond formation and treatment of fumed silica is a good idea, but the cost is too high, at present common approach is the hydroxyl silicone oil, but only additives is not enough, also need in the production process adopts the process control
At present commonly used hydroxyl silicon oil, hydroxyl content in 8%. Viscosity around 20.. Process is to eat 8 hours after the powder is placed, and then high temperature treatment. This silicone oil can more thorough treatment of silica surface hydroxyl. If you take the customer to use, it is not much required. But the real production is still not good control, we want to help.
This paper is from Shenzhen,, id=557?
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