It can be seen from the appearance that one is solid and the other is liquid.
1, liquid silica gel is in liquid state and has fluidity. It is a food-grade material with high transparency and high safety. No auxiliary materials such as vulcanizing agent are added during molding, and the materials are sealed for molding. ?
2. Solid silica gel is in a solid state and has no fluidity. It is also a transparent and environmentally friendly material. When molding, vulcanizing agent is needed to speed up vulcanization molding time, and mold opening molding is adopted.
Second, the difference between liquid silica gel and solid silica gel from the field of use
1, liquid silica gel is generally used in baby products, kitchen products and medical products, which can directly contact food and human body.
2. Solid silica gel is generally used for daily necessities, industrial sundries and auto parts.
3. Safety of liquid silica gel and solid silica gel: Liquid silica gel is a food-grade material with high transparency and good safety. No auxiliary materials such as vulcanizing agent are added during molding, and the materials are sealed for molding. Solid silica gel is a transparent material. When molding, vulcanizing agent should be added to speed up vulcanization molding time, and mold opening molding should be adopted.
Third, the difference between liquid silica gel and solid silica gel molding methods
1. Liquid silicone rubber is injection molded liquid silicone rubber (LSR): the full name is injection molded liquid silicone rubber, and the vulcanization equipment is injection molding machine.
The injection molding machine has a very simple process (no manual processes such as batching, mixing, cutting and high-temperature glue placement, etc.), just a
Only one worker is needed to pick up the product), the product has high precision (all manual procedures are replaced by machines before molding) and high output (mixed with A/B glue)
It can be molded in a few seconds at a certain temperature), saving people, electricity and materials, and can produce all products produced by high temperature glue.
In industrial liquid silica gel, sodium in water glass is usually removed by ion exchange to prepare silica sol. It is a translucent milky white liquid with high stability. Silica sol becomes a porous solid after drying. The specific molding process is as follows:
(1) Rubber compound: This ready-made material can be colored and catalyzed according to your processing equipment and end use.
(2) Substrate: This silicone polymer also contains reinforcing filler. Rubber-based materials can be further mixed with pigments and additives to form rubber compounds to meet your color and other manufacturing requirements.
(3) Liquid Silicone Rubber (LSR): This two-component liquid rubber system can be pumped into appropriate injection molding equipment and then thermally cured into molded rubber parts.
(4) fluorosilicone rubber compound and base material: fluorosilicone rubber retains many key properties of silicone, in addition, it also has superior chemical resistance, fuel resistance and oil resistance.
Synthetic rubber with silicon atoms and oxygen atoms alternately arranged in the main chain and organic groups on silicon atoms. The organic group in the molecule can be -CH3, -C2H3 or -C6H5, which is called methyl, vinyl or methylphenyl silicone rubber. Silicone rubber is a kind of special rubber with high and low temperature resistance (-60 ~ 250℃), ozone resistance and good electrical insulation.
Silicone rubber is a special synthetic elastomer, which is made of linear polysiloxane mixed with reinforcing filler and vulcanized under heating and pressure. It perfectly balances mechanical properties and chemical properties, so it can meet the requirements of many demanding applications today.
2. Solid silica gel molding means that the raw materials are solid blocks, and after being mixed by a blender, the product and the mold are cut into appropriate sizes by a cutting machine.
Small and thick, and then put into the mold, press molding at a certain temperature under the pressure molding machine. When demoulding, it is similar to plastic products, and the mold needs to be cleaned.
(1) Solid silica gel is made of sodium silicate as raw material, hydrolyzed into gel in acidic medium, and then aged, washed and dried. Depending on the water content, it is a translucent or white solid. Commercial products include irregular particles, spherical and microsphere silica gel, which is often used as catalyst carrier in fluidized bed operation.
(2) As a catalyst carrier, silica gel is usually soaked in a solution containing catalytic active components, so that the solution is adsorbed in the pores of the silica gel, and the active components are distributed on the surface of the silica gel after drying, activation and other procedures. The pore structure of silica gel has an important influence on the performance of supported catalysts, such as pore volume and pore size distribution of silica gel. Traditionally, silica gel with average pore size less than 15 ~ 20 is called fine pore silica gel; The average pore size is greater than 40 ~ 50, which is called coarse pore silica gel.
(3) However, the pore structure is not conducive to the diffusion of reactant molecules, on the contrary, it will reduce the utilization rate of the inner surface of the catalyst, and the product molecules generated in deep pores are not easy to escape from the pores, which is easy to cause deep side reactions. The pore structure of silica gel is related to the manufacturing method and conditions, such as gel formation, aging, pH, temperature and time during washing. The commercially available silica gel can be reamed by reaming treatment. The common method is to put it in an autoclave and add water or saline solution (such as sodium carbonate and sodium acetate) for hot pressing. For example, after hot pressing at 320℃ and 10MPa, silica gel with specific surface area and average pore diameter of 135m2/g and 123 can be changed to 26.9m2/g and 508 respectively.