Liquid silicone and solid silicone can be distinguished by physical appearance, the field of use, and the molding method.
The different appearance between liquid silica gel and solid
There are two physical appearance differences between what we usually call silica gel, one is flowing liquid and the other is solid.
1，Liquid silica gel is in a liquid state and has fluidity. It is a highly transparent and safe food-grade material. It does not add auxiliary materials such as vulcanizing agents during molding and is sealed for molding.
2，The solid silica gel is in a solid-state and has no fluidity. It is also a transparent and environmentally friendly material. When curing, it is necessary to add a vulcanizing agent to speed up the vulcanization molding time, and open-mold injection molding.
The difference between liquid silica gel and solid
1，Liquid silicone is generally used in baby products, kitchen supplies, adult products, and medical supplies. It can directly contact food and the human body. Products such as silicone pacifiers, baby bottles, tooth gels, silicone pads, ice trays, cake molds, and diving Mirrors, artificial human organs, medical silicone chest pads, silicone dolls, mobile phone cases, silicone medical balloons, silicone cable ties, etc.
2，solid silicone is generally used in daily necessities and industrial miscellaneous parts and automotive accessories, products such as buttons, silicone gifts, silicone bracelets, silicone watches, key cases, fingertip gyro, etc.
3，Safety of liquid silica gel and solid silica gel: Liquid silica gel is a highly transparent and safe food-grade material. It does not add auxiliary materials such as vulcanizing agents during molding and is sealed for molding. Solid silica gel is a transparent material. When curing, it is necessary to add a curing agent to speed up the curing time.
The difference between the process method of liquid silica gel and solid silica gel
1，Liquid silicone is injection molding liquid silicone rubber (LSR): its full name is injection molding liquid silicone rubber, and vulcanization equipment is an injection molding machine.
The injection molding machine has a very simple process (no need for manual processes such as batching, rubber mixing, cutting, and placing in the high-temperature glue process, only one worker needs to take the product), and the product has high accuracy (all manual procedures before molding All are replaced by machines), high output (A / B glue mixed at a temperature of 130 degrees for a few seconds), many advantages such as saving labor, electricity, and materials, can produce all products produced by high-temperature glue.
Liquid silica gel is generally used in the industry to make sodium sol from sodium silicate by the ion-exchange method. It is a translucent milky white liquid with high stability. The silica sol becomes a porous solid after drying.
Liquid silicone molding process.
(1) Compound rubber: This ready-to-use material can be colored and catalyzed according to your processing equipment and end-use.
(2) Base material: This type of silicone polymer also contains reinforcing fillers. The rubber base can be further mixed with pigments and additives to form a compound rubber to meet your color and other manufacturing requirements.
(3) Liquid Silicone Rubber (LSR): This two-component liquid rubber system can be pumped into a suitable injection molding equipment and then heat-cured into a molded rubber part.
(4) Fluorosilicone rubber compound and base material: Fluorosilicone rubber maintains many key properties of silicone. In addition, it has excellent chemical resistance, fuel and oil resistance.
The main chain of rhenium is a synthetic rubber composed of alternating silicon and oxygen atoms with organic groups on the silicon atoms. The organic group in the molecule may be -CH3, -C2H3 or -C6H5, etc., and is correspondingly called methyl, vinyl or methyl phenyl silicone rubber. Silicone rubber is a special rubber that is resistant to high and low temperatures (-60 to 250 ° C), resistant to ozone and has good electrical insulation properties.
Organic silicone rubber is a special synthetic elastomer produced by mixing linear polysiloxane with reinforcing filler and vulcanizing under heat and pressure. It perfectly balances mechanical and chemical properties, so it can meet many of today’s demanding applications.
2, solid silicone molding is the raw material is a piece of solid, after mixing by a kneading machine, the cutting machine cuts the product and the mold into a suitable size.
Small and thick, then put into the mold, press molding at a temperature of 170 degrees under a pressure forming machine. It is similar to plastic products when demolding, and it also needs to clean the mold.
Solid silicone molding process.
(1) In the industry, solid silica gel uses water glass (sodium silicate) as raw material, hydrolyzed to form a gel in an acidic medium, and then made into silica gel through aging, washing, drying and other processes. According to the difference in water content, it is half. Transparent or white solid. Commercially available products include irregular granular, spherical, and microspherical silica gels, which are often used as catalyst carriers in fluidized bed operations.
(2) When used as catalyst support, silica gel is usually immersed in a solution containing a catalytically active component, the solution is absorbed in the pores of the silica gel, and the active component is 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 properties of the prepared supported catalyst, such as the pore volume and pore size distribution of silica gel. Traditionally, silica gels with an average pore size of less than 15-20 are referred to as fine-pored silica gels, and those with an average pore size greater than 40-50 are referred to as coarse-pored silica gels.
(3) However, the pore structure is not conducive to the diffusion of reactant molecules, but it will reduce the utilization of the internal surface of the catalyst, and the product molecules generated at the depth of the pores will not easily escape from the pores, and it is easy to cause deep side reactions.
The pore structure of silica gel is related to the manufacturing method and conditions, such as gelation, aging, pH, temperature, the time during washing, etc. The commercially available silicone can be reamed by a reaming process.
The common method is to place it in an autoclave and add water or a salt-containing aqueous solution (such as sodium carbonate, sodium acetate) for hot pressing. For example, hot pressing at 320 ° C and 10 MPa can make the specific surface area and average pore diameter respectively The 135 m2 / g and 123 silica gels became 26.9 m2 / g and 508.
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