In the silicone industry, we often hear liquid silicone and solid silicone, so what is liquid silicone and what is solid silicone? What is the difference between liquid silicone and solid silicone?
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What are liquid silica gel and solid silica gel?
Compared with solid high temperature vulcanized silicone rubber, liquid silica gel is liquid glue, milky white, with good fluidity, fast vulcanization, safer and more environmentally friendly, and can fully meet food-grade requirements. Solid silica gel is a saturated polymer elastic material, which has the characteristics of high temperature resistance, cold resistance, solvent resistance, tear resistance, anti-sticking, electrical insulation, chemical resistance, etc., and has a wide range of applications.
Methods of forming liquid silica gel and solid silica gel products
- Liquid silicone is injection molding liquid silicone rubber (LSR): the full name is injection molding liquid silicone rubber, and the vulcanization equipment is an injection molding machine. The injection molding machine has a very simple process (no batching, compounding, cutting and other manual processes are required in the high temperature glue process, only one worker can take the product), high product precision (all manual procedures are replaced by machines before molding), output High (A/B glue mixed into it can be formed in a few seconds at a certain temperature, saving manpower, saving electricity, saving materials and many other advantages, and can produce all products produced by high temperature glue! It is the mainstream development of the silicone industry in the future.
- Solid silica gel molding is a solid material. After mixing by the mixer, the cutter cuts the product and the mold is suitable. Small and thick, after being put into the mold, the pressure forming machine is formed at a certain temperature. When demolding is similar to a plastic product, the mold also needs to be cleaned.
How to distinguish between liquid silicone and solid silicone products
Liquid silicone products have high temperature resistance, low temperature without loss of elasticity, and their chemical resistance, antibacterial and air permeability characteristics, which make them have excellent drawing resistance and low compression long-term deformation, and the product has a plastic injection port. The solid silicone gel has a transparent bottom, vulcanizing agent or other fragrance covering the vulcanizing agent, and the product has no glue injection port.The procedure of liquid silicone molding
- Rubber compound: This ready-to-use material can be colored and catalyzed according to your processing equipment and end use.
- Base material: This type of silicone polymer also contains reinforcing fillers. The rubber base can be further compounded with pigments and additives to form a compound that meets your color and other manufacturing requirements.
- Liquid Silicone Rubber (LSR): This two-component liquid rubber system can be pumped into appropriate injection molding equipment and then heat cured into molded rubber parts.
- Fluorosilicone rubber compound and base material: Fluorosilicone rubber maintains many key properties of silicone, in addition, it has excellent resistance to chemicals, fuels and oils.
Silicone rubber is a special synthetic elastomer formed by mixing linear polysiloxane with reinforcing filler and vulcanizing under heating and pressure conditions. It has the perfect balance of mechanical and chemical properties to meet many of today's demanding applications.
Procedure for solid silicone molding
- In industry, solid silica gel is made of water glass (sodium silicate) as raw material, hydrolyzed in acidic medium to form gel, and then made into silica gel through aging, washing, drying and other processes. 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.
- When used as a catalyst carrier, the silica gel is usually immersed in a solution containing catalytically active components, so that the solution is absorbed 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 properties of the prepared supported catalyst, such as the pore volume and pore size distribution of silica gel. Traditionally, silica gel with an average pore size of less than 15-20 is called fine-pored silica gel; with an average pore size greater than 40-50, it is called coarse-pored silica gel.
- However, the pore structure is not conducive to the diffusion of reactant molecules, but it can reduce the utilization rate of the inner surface of the catalyst, and the product molecules generated deep in the 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, time, etc. during washing. The commercially available silica gel can be expanded by the pore expansion treatment method. The commonly used method is to place it in an autoclave, add water or add a salt-containing aqueous solution (such as sodium carbonate, sodium acetate) to heat and press it.
Advantages of liquid silicone over solid silicone molding
- Liquid silicone products are formed in a closed environment, which is more environmentally friendly and has no secondary pollution;
- The production efficiency is higher than that of high temperature compression molding;
- The automation of equipment can save labor costs in feeding, measuring and other work;
- Suitable for composite molding: silicone material has good fluidity, low molding pressure, and wide curing temperature range, so in addition to insert molding, composite molding can also be performed.
