Fluorine rubber

Rubber is a very common material in life. The rubber we use is divided into two categories: natural rubber and synthetic rubber. Fluororubber is a very important branch of synthetic rubber. Fluororubber refers to a synthetic polymer elastomer with fluorine atoms on the carbon atom of the main chain or side chain.

With fluorinated hydrocarbon as the main raw material, through the process of emulsion polymerization, under the joint action of initiator initiation, emulsifier emulsification and chain transfer dose, under certain reaction pressure and temperature conditions, the fluorinated rubber emulsion obtained by free radical polymerization mechanism is obtained after demulsification, washing and drying, and the polymer fluorinated rubber is obtained. In production, the molecular weight and molecular weight distribution can be adjusted by adjusting the reaction initiation dose and chain transfer dose to meet the customer's different molding processing methods and requirements of fluorine rubber. Raw rubber and then through a series of mixing, plasticizing, vulcanization and other processes to produce rubber products, can be used in many fields.

1 Types of fluoroelastomers

Among these fluoroelastomers, 26 fluoroelastomers formed by binary copolymerization of vinylidene fluoride and hexafluoropropylene, and 246 fluoroelastomers formed by copolymerization of three monomers of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene, are collectively referred to as 26 types of fluoroelastomers, which are currently the largest production and most widely used in the field of application.

In addition to the three monomers of vinylidene fluoride, hexafluoropropene and tetrafluoroethylene fluoride, we also need to add the monomer containing iodine or bromine for copolymerization, or introduce iodine or bromine into the molecular structure of fluororubber through fluoroalkyl iodide chain transfer agent.

Customers buy raw rubber, after a series of mixing, plasticizing, vulcanization and other processes to prepare fluorine rubber products. At present, the most commonly used vulcanization method is polyalcohol vulcanization with bisphenol AF, which is widely used because of its fast vulcanization speed and stable sulfide performance. In addition, organic peroxides can also be used as curing agent for curing.

2 fluorine rubber properties

As a kind of synthetic polymer elastomer, fluorine atoms are contained in the carbon atoms of the main chain or side chain of its molecules. The introduction of fluorine atoms affects the properties of fluorine rubber in many aspects.

First of all, fluorine atom has strong electronegativity, and then the C-F bond formed with carbon atom has high bond energy, which improves the stability of molecular structure. Secondly, the radius of fluorine atom is very small, equivalent to half of the length of C-C bond, which makes the fluorine atom closely arranged around the carbon atom, forming the protection barrier of C-C bond, which gives the chemical inactivity of the carbon-carbon bond of fluorine-containing polymer elastomer.

In addition, the bond energy between the fluorinated carbon atom and other atoms is also improved correspondingly, thus improving the heat resistance and corrosion resistance of fluorinated polymer elastomer.

Since fluoroelastomer is generated by the copolymerization of fluoroolefin, C-C bonds in the molecular chain of fluoroelastomer are all in a saturated state, which reduces the possibility of degradation and fracture of the main chain caused by oxidation and pyrolysis at high temperature.

Vinylidene fluoride rubber has excellent heat resistance, good weather resistance, ozone resistance, oil resistance and chemical resistance. It is mainly used for 〇 type sealing rings, sealing materials and gaskets and other industrial parts under harsh conditions.

The heat resistance of fluoroelastomers is superior to all other synthetic elastomers. The 26 types of fluoroelastomers can be used for a long time at 250℃ and for a short time at 300℃. However, when fluorine rubber is used at high temperature, its physical and mechanical properties, such as tear resistance, decrease obviously.

Fluoroelastomer can work in all kinds of lubricating oil, hydraulic oil, fuel oil, concentrated acid and concentrated oxidant at 250℃ for a long time, and its stability is better than other synthetic adhesives. Peroxide vulcanization is better than polyalcohol vulcanization products oil resistance, fluorine rubber heat resistance and water vapor performance, to the development of organic peroxide vulcanization fluorine rubber technology has been solved.