Fluorosilicone rubber is a new material developed on the basis of organofluorine and organosilicon, which makes up for the deficiencies of organosilicon in oil resistance, chemical corrosion resistance and extreme low temperature resistance, the advantages of organosilicon and organofluorine are complementary. Polytrifluoropropyl methylsiloxane, the main chain of which is still made up of siloxane bonds, is used as the basic polymer for fluorosilicone rubber, but some of the methyl groups on silicon atoms are replaced by fluorine-containing organic groups (usually trifluoropropyl groups) .

    The fluorosilicone rubber combines the silicon-oxygen bond with high bonding energy and the carbon-carbon bond with the fluorocarbon bond which has the shielding effect on the carbon-carbon bond, and shows excellent properties of high and low temperature resistance, environmental aging resistance, oil resistance and chemical corrosion resistance, once developed successfully, it will be applied to the aviation field.

    Fluorosilicone rubber market

    At present, the large-scale chemical enterprises in the United States, Germany, Japan and other countries are actively carrying out research on fluorosilicone rubber, the global annual output of fluorosilicone rubber is about 10kt. The global fluorosilicone rubber market is growing at a compound annual growth rate of 7.4 per cent and is expected to grow to US $328m by 2026. 

   At present, some domestic manufacturers have been able to industrialized production of fluorosilicone rubber based polymers, but its RTV fluorosilicone rubber products are still under development. Because of the environmental requirements in the production of fluorosilicone rubber monomer and polymer, as well as the problems of raw material price and process difficulty, the cost of fluorosilicone rubber based polymer is on the high side.

   Introduction of fluorosilicone rubber

   The main chain of fluorosilicone rubber is ー Si ー O ー bond structure, and ー CH2CH2CF3 structure is formed by introducing polar fluorine atom (such as trifluoropropyl) into the side chain, in addition, the shorter bond length of C-F bond can form a good shielding effect on C-C bond, which greatly improves the oil resistance and solvent resistance of rubber, it can be used as an elastomer with good resistance to non-polar media at the temperature of -68 ° C ~ 232 ° C. Therefore, fluorosilicone rubber is widely used in high-end locomotives and military aerospace seals.

  Properties of fluorosilicone rubber

  FVMQ fluorosilicone rubber o-ring in the maintenance of silicone materials in the heat resistance, cold resistance, high voltage resistance, resistance to weather brittleness and other outstanding characteristics of the basic, because of the introduction of fluorine content ester, it also has organic fluorine raw materials excellent resistance to hydrogen-based organic solvents, acid and alkali resistance, corrosion resistance and lower surface characteristics.

  1, Acid and alkali resistance, washing resistance, chemical resistance

   Compared with hydroxyethyl silicone rubber, fluorine silicone rubber has excellent acid-alkali resistance, water-washing resistance and chemical resistance, even compared with fluorine rubber, acid-alkali resistance and water-washing resistance are also excellent. In the same material, temperature, time after the prepreg information shows that the use of high-quality performance, it can be said that fluorosilicone rubber is the only non-polar materials in -68 ° C ~ 232 ° C of polyurethane elastomer. Fluorosilicone rubber also has good resistance to methanol gasoline, even in the gasoline/ethanol mixed management system, its vulcanized rubber strength, tensile strength, volume change are not big, after 500h long-term prepreg experiment, all kinds of physical properties have not changed basically.

  2. Heat resistance

  The dissolution of fluorosilicone rubber at high temperature is the same as that of silicone rubber, that is, air oxidation of main chain, main chain breakage, main chain decomposition reaction and resulting in a variety of complex reactions. Because the dissolved material can also cause the main chain to break, so the temperature resistance is generally worse than silicone rubber, at 200 degrees C at the beginning of the air oxidation embrittlement. However, it can be obviously improved by adding a small amount of non-halogen flame retardants such as iron, titanium, greek-earth metal oxides, etc. . The harm of temperature to fluorosilicone rubber is bigger than that of silicone rubber, but smaller than that of fluorosilicone rubber. The service life of fluorosilicone rubber under the standard of 150 ° C × 2000H, 175 ° C × 5000H, 200 ° C × 4000H was also studied.

  3. Cold hardiness

   Fluorine silicone rubber and general silicone rubber, the ultra-low temperature performance is excellent. Because fluorosilicone rubber is a linear polymer with soft SI-O leading chain, it is better than Fluorosilicone with C-C leading chain at ultra-low temperature. The ultra-low temperature of LS-2370U is stronger, and the ductility temperature is -89 ° C, while that of General LS-2370U is -30 ° C.

 4, Electrical performance, radiation source characteristics

 The electrical properties of fluorosilicone rubber are similar to those of ordinary silicone rubber, but it is very valuable that there is little change in high temperature, ultra-low temperature, wet-cold, oil, organic solvents, chemicals, reactive oxygen species and so on. The radiation resistance of fluorosilicone rubber is not obvious, but the embrittlement of fluorosilicone rubber is better than that of hydroxyethyl vinyl silicone rubber.

  5. Physical performance

  Fluorine silicone rubber and general silicone rubber, vulcanized rubber impact toughness (very tear compressive strength) is relatively low. Therefore, improving and improving the compressive strength of fluorosilicone rubber is also a key issue.

  6. Other characteristics

  The weather-resistance of fluorosilicone rubber is very good, even after five years of exposure, still maintain excellent characteristics. Reactive oxygen species (Ros) is one of the most abundant gases in the process of embrittlement of polyurethane elastomers, but no cracking or cracking has been found in fluorosilicone elastomers based on dynamic or static data. In addition, fluorine silicone rubber mold removal, physiological plasticity, anticoagulation is also very good.

  Points for attention in fluorosilicone rubber production process

  Because the fluorosilicone rubber price is expensive, the rubber material easy pollution, thus affects the performance, therefore to the fluorosilicone rubber production process is extremely strict.

  1. Keep the production environment and equipment clean

  During the storage and transportation of fluorosilicone rubber, dust impurities are prevented from coming into contact with the rubber.

  As fluorosilicone rubber has the characteristics of electrostatic ash absorption, it is necessary to clean the dust-free workshop in the production environment with special equipment. Workers should wear clean clothes and hats when entering or leaving the workplace.

 Clean cutting tools, weighing trays and mill rollers. Rubber mixing process to prevent contamination of rubber gloves.

  2. Mixing and vulcanization

  When the temperature of the open mill roller is 18 ° C ~ 28 ° C, the rubber-making performance is better. For long-term storage of the use of rubber needs to be re-refined to ensure that the material mixing evenly. The curing die must be chrome plated. Fluorine silicone rubber to the second stage vulcanization, in the electric blast box, generally: 200 ° C × 4 ~ 6 hours.