DE1495991A1 - Process for the production of organosilicon polymers - Google Patents

Description

Process for the production of organosilicon polymers Priorities: dated Aug. 1, 1963 in the USA under serial numbers 299 171, 299 195 and 299 154 these The invention relates to a process for the preparation of silicone type polymers which t> is (diarylsilyl) benzene units and diphenylsiloxane units and Copolymers are characterized by improved thermal stability. In The silicone technology has long known that the incorporation of aromatic groups increases the thermal stability of such polymers in organopolysiloxane polymers, and polymeric materials that consist entirely of diphenylsiloxane units, are well known in the art. While these materials increased thermal stability possess, on the other hand, they are characterized by an extreme brittleness that makes them quite inadequate for most silicone polymer uses.

The present invention is based on the discovery of a new class of organosilicon polymers having the formula where n is greater than 1, e.g. B. between 3 and 50 or more. These polymers have the thermal stability expected of phenyl-containing organopolysiloxanes, but also lack the extreme brittleness previously commonly found in such materials.

The polymers of the present invention are prepared by reacting 1,4-bis- (diphenylhydroxysilyl) -benzene and diphenylchlorosilane produced. Usually is the reaction for the preparation of the interpolymers according to the present invention by using equimolar proportions of 1,4-bis (diphenylhydroxysilyl) benzene and diphenyldichlorosilane. Usually this is diphenyldichlorosilane slowly to a solution of the other reactant in the presence of a hydrogen halide acceptor, such as pyridine, and added in the presence of a suitable solvent. Among those Any material that is a solvent for the solvent can be mentioned Reaction partner and is inert under the conditions of the reaction. A special one the desired solvent is tetrahydrofuran. Generally the pyridine lies in an amount sufficient to provide at least one mole of pyridine per mole of diphenyldichlorosilane to deliver, but the implementation can also be carried out in a satisfactory manner, if one uses the pyridine in an equivalence ratio of i, 2 5 to 5 mol per gtol Diphenyldiohiorsilane used The amount of solvent used is not critically, but a sufficient amount is usually used to obtain a complete Ensure loosening of the reactants. Usually the related Amount of solvent 1 to 10 parts per part of the reactants and of the hydrogen halide acceptor. The reaction is carried out in the manner that the reaction mixture is preferably stirred for 5 to 20 or more hours only holds at room temperature, the reaction product is filtered off from the reaction mixture and the product stripped under reduced pressure to be in the reaction mixture residual solvent or residual hydrogen halide acceptor to remove.

As is known, 14-bis- (diphenylhydroxysilyl) -benzene is made from 1,4-bis- (diphenylchlorosilyl) -benzene made by making a solution containing 10 parts of the latter compound and 45 parts Contains tetrahydrofuran, dropwise to a suspension containing 10 parts of sodium bicarbonate, Contains 35 parts of ether saturated with water. During the addition will Carbon dioxide is evolved, and the reaction mixture is at for about 16 hours Room temperature mixed. Then the reaction mixture is filtered with suction, to remove the sodium salts, and the filtrate is distilled to a solid Leave residue with a melting point of 180 to 1900 C. This backlog is then cleaned in a Soxhlet extractor with toluene and yields 5.2 parts 1, 4-bis- (diphenylhydroxysilyl) -benzene in the form of broad needles, ranging from 212 to 2140 Melt C.

The 1,4-IXis- (diphezylchlorosilyl) -benzene can in a known manner by reacting a butyllithium solution with p-dibromobenzene. A solution containing 2.2 moles of butyllithium per liter of solvent that is a mixture of 3 parts by volume of heptane and one part by volume of pentane is used as a butyllithium source used. One liter of the butyllithium solution is made under a nitrogen atmosphere to 236 g (1 mol) of p-dibrornobenzene in one liter of petroleum ether was added. After stirring the mixture at room temperature for 20 hours is then added dropwise to 964 g (4 mol) of diphenyldichlorosilane, which dissolved in one liter of petroleum ether is given. During the addition, the mixture is allowed to reflux gently Cook and then stir the reaction mixture at room temperature for 8 hours. The reaction mixture is filtered and the filtration residue is stirred in toluene and filtered again. The toluene filtrate is then distilled to give 250 g of an oily semi-solid residue to give, which is washed with petroleum ether to release impurities. The resulting solid is dried in an oven at 1100 C to 75 g a white powder with a melting point of 175 to 1800 C. This Material is further purified and recrystallized from ethyl orthoformate gives 1,4-bis (diphenylchlorosilyl) benzene with a melting point of 183 to 185 ° C.

The following example serves to explain the invention.

Example A polymer according to the present invention was made by reaction obtained from 1,4-bis (diphenylhydroxysilyl) benzene with diphenyldichlorosilane. Diphenyldichlorosilane (1.88 parts) was added dropwise to a solution containing 3.52 parts of 1,4-bis (diphenylhydroxysilyl) benzene, one part of pyridine and 25 parts of anhydrous tetrahydrofuran. It made up A white precipitate appeared and the mixture was allowed to stand at room temperature for about 16 hours stirred and then filtered.

The piltrate was distilled to remove the solvent, leaving a resinous residue which solidified at room temperature to give a resin product having the following formula: The elevated temperature weight loss of this product is considerably less than that of a high molecular weight diphenylpolysiloxane. For example, the weight loss after heating at 355 ° C for four hours was only 18%. After -8 hours of such heating it continued gently. Weight loss only 3.6%. After heating again for four hours at 4100 C, the additional weight loss was only 2.5%.

While the above example is the production of a single mixed polymer explained according to the present invention, it is understood that polymers, which are different from the material of the example, by increasing or decreasing the temperature at which the reaction eriolgt, can be produced. It was found that the molecular weight is approximately a function of the reaction temperature, eo that lower molecular weight materials can be made if the reaction is carried out at temperatures which are slightly below room temperature while higher molecular weight materials are obtained if one Temperatures above room temperature, such as. B. in the order of 25 to 500 a applies. There is no particular benefit in using the reaction between the diphenyldichlorosilane and the 1,4-bis (diphenylhydroxysilyl) benzene at temperatures carries out, which are significantly above 500 C.

The polymer materials of the present invention can be excellent used as insulation for electrical conductors. For example, the Materials according to the present invention are dissolved in diphenyl ether and form Solutions with a solids content of about 50%. Electrical conductors, such as copper wires, can through these solutions and then through a wire tower for evaporation of the solvent are carried out, being a tough, flexible, continuous Film of the polymer according to the present invention as insulation on the electrical Ladders.

Claims (1)

Claim Process for making a polymer material having the following general formula: wherein n is a number greater than 1, characterized in that 1,4-bis- (diphenylhydroxysilyl) -benzene is reacted with diphenyldichlorosilane in the presence of a hydrogen halide acceptor at a temperature below 50 ° C and the reaction product is then recovered.