A kind of preparation method of thermally vulcanized fluorosilicone rubber raw rubber

Abstract

The invention relates to a preparation method of heat curing fluorosilicone raw rubber. The preparation method comprises the following steps: adding D3F and D4Vi into a reactor and then dehydrating D3F and D4Vi, adding prepared potassium silanolate catalyst pre-polymer, heating, introducing nitrogen and stirring to carry out polymerization, wherein the temperature is 60-115 DEG C and the reaction time is 20-100min, neutralizing with a neutralizer until the reactant is neutral, and finally, removing small molecular substances from the material, reducing temperature and discharging. Due to the adoption of the potassium silanol catalyst pre-polymer with high activity, the reaction temperature is low, the accelerant is not required, an end-capping reagent is not required in the polymerization process, and the nitrogen purging manner is adopted in the stage of removing the small molecular substances from the material, the volatile matter of the heat curing fluorosilicone raw rubber is reduced; the prepared heat curing fluorosilicone raw rubber can be widely used in the fields of aerospace, petrochemical industry, automobiles, artificial organ, and the like, and has a good promotional value.

Description

technical field [0001] The invention relates to a preparation method of fluorosilicone rubber raw rubber, in particular to a preparation method of heat vulcanized fluorosilicone rubber raw rubber suitable for aerospace, automobile, machinery, petrochemical, artificial organs and other fields, belonging to the organic chemical industry technology field. Background technique [0002] Fluorosilicone raw rubber is based on -Si-O-Si- as the main chain, and the silicon atom contains a methyl group (-CH 3 ) and 3,3,3-trifluoropropyl and a small amount of methyl, vinyl (CH 2 =CH-) The linear high molecular polymer of siloxane chain link, its special chemical structure determines that it has both the excellent high and low temperature performance of silicone rubber, and the excellent high temperature resistance, chemical medium resistance and oil resistance of fluororubber , is a new type of synthetic polymer material. Fluorosilicone rubber is mainly divided into liquid fluorosili...

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Problems solved by technology

[0004] The synthesis of raw fluorosilicone rubber mostly adopts the bulk polymerization process, because D 3 F has high reactivity, the polymerization reaction will increase the viscosity of the system in a short period of time, and the polymerization process has the problem of difficult mass and heat transfer, resulting in difficult control of the molecular weight of raw rubber, wide molecular weight distribution, and low vinyl content. And other problems seriously affect the processing performance of fluorosilicone rubber and the performance of vulcanized products

[0005] The catalysts used in the synthesis of fluorosilicone raw rubber are generally lithium hydroxide, sodium hydroxide and their silicon alkoxides, among which sodium silicon alkoxide catalysts are often used, such as US Patent4317899, US Patent6492479B2, all of which are sodium silicon alkoxide catalysts, which belong to Balance the catalyst, there will be a "bite back" reaction in the reaction process, the occurrence of the "bite back" reaction will make the system contain more small molecules, resulting in a decrease in yield, and the catalyst must be neutralized at the end of the polymerization, otherwise it will Two results are caused. One is that high temperature conditions are required in the process of removing low boiling of raw rubber. Under these conditions, the existing catalyst will make the "bite back" reaction more serious and make the molecular weight distribution uneven; the other is that the residual catalyst will Affect the high temperature stability of raw rubber, which is unfavorable for mixing

Chinese patent document CN1724580A (application number 200510026689.6) discloses a method for preparing high molecular weight fluorosilicon polymers. Sodium silanolate is used as the catalyst to prepare a series of high molecular weight fluorosilicon polymers. However, there is no Neutralize the catalyst, which will affect the thermal stability of the raw rubber

[0007] Chinese patent document CN102225997A (application number: 201110146542.6) discloses a preparation method of high molecular weight fluorosilicone rubber raw rubber, first synthesizing a vinyl ring body and a lithium silicon alkoxide catalyst, and then combining with D 3 F reacts under certain conditions to obtain high-molecular-weight raw rubber with uniform vinyl distribution. Since lithium silyl alkoxide is a non-equilibrium catalyst, neutralization is not required at the end of polymerization, but with lithium silyl alkoxide catalyst, the temperature required for polymerization is higher, and The preparation of vinyl rings makes the synthesis process of raw rubber more cumbersome

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