What are the advantages and disadvantages of liquid silicone adhesive compared with silicone adhesive
liquid silicone adhesive is a liquid state, with liquidity;silicone adhesive is solid and has no fluidity.
Distinguish from the field of use
1. liquid silicone adhesive is generally used in baby products, kitchen products and medical products, which can directly contact with food and human body.
2. silicone adhesive is generally used in daily necessities, industrial miscellaneous parts and automobile accessories.
3. Safety of liquid silicone adhesive and silicone adhesive: liquid silicone adhesive is a food grade material with high transparency and safety. During molding, no vulcanizing agent and other auxiliary materials are added.silicone adhesive is transparent material, vulcanizing agent is needed to speed up the vulcanizing forming time, open mold feeding molding.
Distinguish from the forming mode
1, liquid silicone is injection molding liquid silicone rubber (LSR) : full name is injection molding liquid silicone rubber, vulcanization equipment is injection molding machine.Injection molding machine process is very simple, high precision products, high yield (A/B adhesive mixture in A few seconds at A certain temperature molding), save people, save electricity, save materials and other advantages, can produce all high temperature rubber products;It is a main trend of silicone rubber material development in the future.
2. silicone adhesive molding is made of solid materials. After mixing by mixing machine, the material cutting machine cuts products and molds of appropriate size and thickness, and then puts them into molds, which are molded by pressure molding machine at a certain temperature.Demoulding and plastic products similar, also need to clean the mold.
From the production of finished products
liquid silicone adhesive has high transparency and no odor.
silicone transparent bottom, vulcanizing agent or other cover vulcanizing agent fragrance, product without injection mouth.
What is the difference between liquid silicone adhesive and silicone adhesive forming process
1, silicone adhesive in industry is made of sodium silicate (sodium silicate) as raw material, hydrolyzed in acidic medium to produce gel, and then made into silicone adhesive through aging, washing, drying and other processes. According to the different water content, it is translucent or white solid.Commercial products are irregular granular, spherical, microspherical silicone adhesive, commonly used as catalyst carrier in fluidized bed operations.
2. When used as catalyst carrier, silicone adhesive is usually soaked in the solution containing catalytic active components, so that the solution is absorbed in the pores of silicone adhesive, and the active components are distributed on the surface of silicone adhesive through drying, activation and other procedures.The pore structure of silicone adhesive has important influence on the properties of supported catalyst, such as pore volume and pore size distribution of silicone adhesive.Traditionally, the average pore diameter is less than 15 ~ 20A silicone adhesive, called fine pore silicone adhesive;The average pore diameter is greater than 40 ~ 50A, which is called coarse pore silicone adhesive.
3. However, the fine pore structure is not conducive to the diffusion of reactants, but can reduce the utilization rate of the catalyst's inner surface, and the product molecules generated in the depths of pores are not easy to escape from the pores, which is easy to cause deep side reactions.The pore structure of silicone adhesive is related to the manufacturing method and conditions, such as gelatinization, aging, pH value, temperature and time of washing, etc.The commercially available silicone adhesive can be expanded by the method of hole expanding, the common method is to put it in the hot pressure kettle add water or add salt aqueous solution (such as sodium carbonate, sodium acetate) hot pressure treatment, for example: in 320℃, 10MPa hot pressure treatment can make the specific surface and average pore diameter of 135m2/g and 123A silicone adhesive into 26.9m2/g and 508A.
The process of liquid silicone adhesive is introduced
liquid silicone adhesive is usually used in industry to make silica sol by removing sodium from water glass by ion exchange method.It is a translucent milky liquid with high stability.The silica sol becomes a porous solid after drying.For example, in the preparation of acrylonitrile (phosphor-molybdenum-bismuth-oxygen)/ silicon oxide catalyst from propylene amination and oxidation, the solution containing active components is mixed with silica sol to form microsphere catalyst by spray drying method.Mainly used in food grade household supplies, maternal and child supplies.