Preparation method of methylphenyl silicone oil with phenyl groups of medium and high content

Abstract

The invention relates to the technical field of silicone industry. In order to overcome the deficiencies in the prior art, the invention provides a preparation method of methylphenyl silicone oil withphenyl groups of a medium and high content, wherein raw materials and intermediates with steric hindrance and electronic effects are selected, and preparation is achieved by utilizing a catalytic dealkylation polycondensation reaction between Si-H and Si-OR. In the molecular chain of the prepared methylphenyl silicone oil with phenyl groups of a medium and high content, PhSiO and Me2SiO chain segments are evenly distributed, and the prepared methylphenyl silicone oil has a structure close to the structure of an alternating copolymer, so that the silicone oil has excellent transparency and temperature resistance, and the content of a by-product cyclic siloxane is extremely low.

Description

technical field [0001] The invention relates to the technical field of organosilicon industry, in particular to a method for preparing methylphenyl silicone oil with medium and high phenyl content. Background technique [0002] Methyl phenyl silicone oil is a product in which methyl groups on some silicon atoms in methyl silicone oil are replaced by phenyl groups. According to the molar content of phenyl groups in all organic substituents, it can be divided into low phenyl silicone oils (5% to 10 %), medium phenyl silicone oil (~25%), high phenyl silicone oil (~45%), etc. The glass transition temperature of low phenyl silicone oil can be as low as -120°C, and the crystallization of polydimethylsiloxane segment can be completely suppressed, so it has excellent low temperature resistance. With the increase of phenyl content, the heat resistance, radiation resistance, lubricity, refractive index, and compatibility with organic materials of silicone oil are all improved. After ...

AI Technical Summary

Problems solved by technology

For a long time, my country's preparation of methyl phenyl siloxane rings has lagged behind foreign advanced levels. The production capacity and scale are weak, and the product quality cannot meet the requirements for the preparation of high-quality silicone oil and raw rubber, which seriously restricts my country's methyl phenyl siloxane production. Application of Phenylsiloxane Materials

[0006] Second, it is difficult to prepare silicone oil with medium and high phenyl content

Moreover, the phenyl content in the linear polymer often deviates greatly from the phenyl content when feeding, especially in the preparation of high phenyl silicone oil, the actual phenyl content is difficult to reach the expected

And when using D 4 Ph with D 4 During copolymerization, under reaction conditions, the breakage of Si-Ph bonds occurs from time to time, resulting in the formation of cross-linked products, which seriously affects the reaction yield and product quality (Polymer Science U.S.S.R., 1966, 8(2): 384-388)

[0007] Third, the product quality of medium and high phenyl silicone oil is difficult to meet the high-end demand

For this reason, the distribution of the two kinds of siloxane chains in the silicone oil molecular chain is not completely random, and there are longer PhSiO homopolymeric segments in the molecular sequence structure, that is, there is a tendency for block copolymerization; and when the PhSiO chain segment After reaching a certain length, there will be a large difference in the refractive index between different segments on the same molecular chain, and the heat resistance of silicone oil will also be severely reduced (Journal of Applied Polymer Science, 2010, 117(5): 2530-2537) , so it is difficult to obtain silicone oil products with good transparency and excellent temperature resistance

[0008] In our previous research, we found that the preparation of medium and high phenyl methyl phenyl silicone oil can be effectively carried out by using catalytic dehydrogenation polycondensation reaction (the reaction formula is shown in the following formula), and the phenyl content can be precisely controlled within the range of 5% to 33%. , but via 29 Si-NMR research shows that the copolymer is not an ideal alternating structure, but there are dimers, trimers, etc. of PhSiO chain links, which shows that disproportionation and rearrangement reactions occurred during the reaction process, and the molecular weight of the obtained silicone oil is the same as that of There is a large deviation from the theoretical value, and its molecular structure is between alternating copolymerization and random copolymerization, and more cyclic siloxanes are generated, which reduces the reaction yield. The reason is that the selected hydrogen-terminated poly The steric hindrance of the Si-H bond in the dimethylsiloxane oligomer is small, and the disproportionation side reaction is prone to occur under the activation of the catalyst.

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