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Continuous cracking method for dimethyl polysiloxane with end sealed by hydroxyl group and rectifying method for the same to preparing cyclosiloxane

A technology of polydimethylsiloxane and octamethylcyclotetrasiloxane, which is applied in the field of continuous cracking and rectification to prepare cyclosiloxane, which can solve the problems of environmental pollution and solvent treatment difficulties, and achieve the improvement of cyclosiloxane Yield and product quality, and the effect of solving solvent handling problems

Inactive Publication Date: 2008-03-26
JIANGXI BLUESTAR XINGHUO SILICONE CO LTD
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Problems solved by technology

[0003] The technical problem to be solved by the present invention is to provide a solvent-free hydroxyl-terminated poly The continuous cracking and rectification of dimethylsiloxane to prepare cyclosiloxane, which not only solves the problem of solvent treatment, but also improves the yield of ring body and product quality

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  • Continuous cracking method for dimethyl polysiloxane with end sealed by hydroxyl group and rectifying method for the same to preparing cyclosiloxane

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Embodiment

[0023] Hydroxyl-terminated polydimethylsiloxane hydrolyzate F1=2644kg / h, composition (wt): MM: 0.06%, D3: 0.5%, D4: 50%, D5: 10%, D6: 2.14%, line body : 37.3% and alkali catalyst (50% KOH aqueous solution), by the KOH aqueous solution of proportioning R=50%: hydroxyl-terminated polydimethylsiloxane hydrolyzate F1 (wt)=1: 100, continuous to cracking kettle 1a Feed, control the reaction temperature of the cracking tank to 135°C, and the reaction pressure to 0.005MPa-A. The vapor phase V1 of the mixture obtained by cracking enters the cracking tower 1t with a pressure of 0.002MPa-A and a temperature of 95°C at the top of the cracking tank from the cracking tank 1a, and cracks The tower 1t is a plate tower, and the vapor-liquid exchange is carried out with the reflux liquid on the tray, and the line body returns to the cracking kettle 1a for re-cracking, and the mixed ring body G1 mainly composed of octamethylcyclotetrasiloxane obtained at the top of the tower is condensed After c...

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Abstract

The present invention discloses process of preparing cyclic siloxane including continuous cracking of hydroxyl group terminated polydimethyl siloxane and rectification. Hydroxyl group terminated polydimethyl siloxane is first hydrolyzed, the hydrolysate is then cracked continuously under the action of alkali catalyst and in vacuum condition to obtain cyclic siloxane mixture, and through further vapor-liquid exchange, re-cracking and vacuum rectifying, the required cyclic siloxane is obtained. The present invention has no solvent for the cracking process, high cyclic siloxane yield, high product quality and convenient continuous operation.

Description

technical field [0001] The invention relates to a method for continuously cracking and rectifying hydroxyl-terminated polydimethylsiloxane to prepare cyclosiloxane. Background technique [0002] Some people in China use dimethyldichlorosilane hydrolyzate hydroxyl-terminated polydimethylsiloxane evaporation, cracking, evaporation to dryness and ring body washing process to prepare cyclosiloxane, but this process has low ring body yield, Poor quality, short production slag discharge cycle, high alkali consumption, and difficulty in device enlargement. Since the early 1980s, there have been reports on the preparation of cyclic siloxane by solvent cracking of dimethyldichlorosilane hydrolyzate in foreign countries. The Jihua Research Institute also published the "Chemical Industry Science and Technology, 2001 Vol.9No.2P.63-65 published "Continuous Cracking Process Development of Dimethyldichlorosilane Hydrolyzate by Solvent Method", which is about the preparation of cyclosiloxa...

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Application Information

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IPC IPC(8): C07F7/21
Inventor 郭守涛吕永雄王继忠尹跃龙陈晓明
Owner JIANGXI BLUESTAR XINGHUO SILICONE CO LTD
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