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What's the processing technics differences between SSR and LSR ?

Sources:其他网站 Date:2016-02-26 

Solid silicone industrially is made by using water glass (sodium silicate) as raw materials, hydrolyzed to generate gel in acidic medium, and after aging, washing, drying and other process. Due to different water content it looks transparent or white solid. There are irregular granular, spherical and spherical silica gel on market, the last kind has better wear resistance, often used as a catalyst carrier in fluidized bed.

When used as a catalyst carrier, usually soaking the silica gel  in catalytic activity component solution, the pores of the silica gel absorbing the solution, after drying and activation procedures, makes active components distributed on the surface of silica gel. The pore structure of silica gel has an important effect on the properties of supporting catalysts, such as pore capacity and pore distribution.Usually, the average pore diameter of less than 15 ~ 20? are porous silica gel; average pore diameter longer than 40 to 50? are wide pore silica gel. The pore structure of the silica gel have high specific surface area, good for the dispersion of the catalytic active component. But the pore structure is not conducive to the diffusion of reactant molecules, that is, not easy to penetrate the catalytic activity in deep pore points, and therefore reducing the catalyst surface utilization ratio, and the product molecules is not easy to escape from the depths of the pore formation, which is easy to cause side reaction in depth. The pore structure is related to manufacturing method and conditions, such as rubber, aging, pH value of washing, temperature and time etc.. By enlarging treatment method, we can enlarge the pores of commercially available silicone gel, the commonly used method is hot pressing processing, placing silica gel in a autoclave water or containing salt water solution (such as sodium carbonate, sodium acetate). For example:  320℃, 10 MPa hot pressing treatment can make the specific surface area and average pore diameter of 135m2/g and 123? Silica gel change into 26.9m2/g and 508?.

Silica sol

In addition to solid silica gel, liquid silica sol is also an important carrier material. the industry usually exchange the glass water desodium Si sol by ion with ion exchange method. It is a translucent milky white liquid, commercially available silica gel's silica content is generally 20% ~ 30%, high up to 50%, and the particle diameter is 100 ~ 200?, some are 1300?. High concentration silica sol is usually using traces of Na2O to maintain its stability. After drying, silica sol becomes porous solid. For example, in producingn silicon oxide catalyst by the production of acrylonitrile by ammoxidation of propene (phosphorus - molybdenum bismuth oxygen) , mixing the solution containing active components and silica sol, then by spray drying method to prepare the microsphere catalyst. Organic silicone rubber is mixed reinforcing filler by linear polysiloxane, generating sulfide special synthetic elastomer in heat and pressure. It perfectly balances mechanical and chemical properties, which can meet many of today's demanding applications.


The silicone rubber excels in the following aspects:

High temperature stability

Inert (odorless)

Transparent, easy to dye

The hardness range, 10 - 80 shore hardness

Resistance to chemicals

Weather torlerable

Sealing performance

Electrical properties

Resistant to compression deformation

In addition to the above superior performance, compared with conventional organic silicone rubber elastomer, they also easy to manufacture. Silicone rubber flow easily, moldable, rolling and extrusion with low energy consumption. Easy processing means the production efficiency is high.




Silicone rubber can be provided in the following form:

Mixed rubber: This material can be colored and catalytic according to your processing equipments and end use.

Base material: this kind of organosilicon polymer containing the same reinforcing filler. Rubber base material can further mix with pigments and additives, forming compound and meet the requirements of your color and other manufacturing.

Liquid silicone rubber (LSR): the two-component liquid rubber injection molding equipment system can appropriate input through the pump, and then heat cured into molded rubber parts.

Fluorosilicone rubber mixing rubber and base material: fluorosilicone rubber kept many of the key properties of silicone. In addition, it also has superior resistance to chemicals, fuel and oil resistance.




The main chain consists of alternative silicon and oxygen atoms, with organic groups in the silicon atoms. Organic groups in the molecule can be CH3, C2H3 or C6H5 and so on, called methyl vinyl or methyl phenyl silicone rubber respectively. Silicone rubber is a kind of special rubber, high and low temperature (-60 to 250 DEG C) resistance, ozone resistance, good electrical insulation. Silicone rubber has three types, high temperature vulcanized silicone rubber (vulcanizing temperature 150 to 200 DEG C), room temperature vulcanizing and addition type.


High temperature vulcanized silicone rubber was successfully developed in 1944 by the United States Ge Corp. In 1952, the United States Tao - Corning L., Tebulaitang and K. Pohl Mahdil developed double component room temperature vulcanized silicone rubber; from 1953 to 1955 successfully made methyl vinyl silicone rubber; from 1956 to 1957 silicon and fluorine rubber was appeared. From 1958 to 1959 to successfully developed single component room temperature vulcanized silicone rubber; after thst, addition silicone rubber products were appeared. There are more than 10 countries the production of silicone rubber in the world. Since the 1980s, the annual growth rate is about 15%. China started all kinds of silicone rubber from the early 60's, now they are mass producting.






Silicone rubber has the following main varieties:

Colorless and transparent high temperature vulcanized silicone rubber, plastic, molecular weight of 35 million to 70 million, dissolved in a solvent such as benzene, product resistance to oxidation, ozone resistance, high frequency electrical insulation good, arc resistance, corona resistant and breathable and on human physiological inertness. As the demanding conditions of wire and cable insulation, seals, catheters, moon shoes etc.. Because of its non carcinogenic, anticoagulant and biological compatibility good, has been widely used in producing both inside and outside the body of the catheter, with intubation, artificial joints.

High temperature vulcanized silicone rubber usually with eight high purity methyl ring siloxane and with - C6H5, - CH = CH2, - CH2CH2 - CF3 groups cyclotetrasiloxane as raw material, acid-base catalyst for open ring polymerization, the removal of catalyst and low volatile fractions derived from silicon rubber. Rubber processing, to join the structure control agent (2 methyl phenyl silicone glycol) and reinforcing filler (fumed silica), antioxidant (Fe2O3), in a mixing machine mixing, after high temperature treatment (about 200 DEG C) and organic peroxides (2, 5 - dimethyl - 2. 5 - di - (tert butyl over hexane oxidation) as the curing agent. Mix into the mold after heating and pressurizing. Some will die after the product after curing. The mix can be extruded into strips, coated pipe, wire and cable.

Room temperature vulcanized silicone rubber is characterized by rubber material can be made into different viscosity, at room temperature can be coated, without high temperature and pressure can be vulcanized, vulcanized to release alcohols, acetic acid and other low molecular products. Room temperature vulcanized silicone rubber has two components and one component of. Two-component room temperature vulcanized silicone rubber for precision casting with elastic mould, dental impression materials and spacecraft ablative coating etc., its raw materials of hydroxyl terminated low molecular polysiloxane to specially prepared, usually in silicone ring body and the water open ring made of, the molecular weight size by the amount of water added to control. RTV-1 silicone rubber seal protection for electronic devices, the use of the main component of the band acetoxy or ketoximino reactive groups such as silane or siloxane, also need special preparation.

Silicone rubber with vinyl terminated polysiloxane and hydrogen polysiloxane as base material, with platinum compounds as catalyst, in slightly above room temperature under the conditions of sulfide:

Sheng SiCHCH2 + HSi Sheng - > Sheng SiCH2CH2Si Sheng such as joining special manufacturing silicone resin as reinforcing agent, transparent and have excellent mechanical properties of vulcanized rubber. It is characterized by that the low molecular weight products can not be released during curing, and can be used for curing the deep part of the forming process. Mainly used for electronic device perfusion coating, as a light guide fiber coating, is also the human body soft tissue filling, facial plastic ideal material.




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