Process of controlling 1.2-structure content and distribution in polybutyldiene

Abstract

A process for controlling the content and distribution of 1,2-structure in polybutadiene features use of a tetrahydrofuran / ethanediol diether (or dibutylether) as its regulation system to make the content of 1,2-structures in 33-37% range and the uniform distribution of 1,2-structures in molecular chain.

Description

technical field [0001] The invention relates to a method for controlling the content and distribution of 1,2-structure in polybutadiene. Background technique [0002] S-EB-S, the hydrogenation product of polystyrene-polybutadiene-polystyrene thermoplastic elastomer SBS, as a new type of thermoplastic elastomer, is resistant to aging compared with SBS, and is widely used in various soft-touch handles , auto parts, wire and cable sheaths, sealing strips, modification of engineering plastics, adhesives and other fields. The S-EB-S thermoplastic elastomer requires that the middle block polybutadiene B of SBS must contain vinyl (1,2-structure) between 35 and 55%, so as to ensure that it becomes an elastomer instead of a plastic after hydrogenation ; In order to ensure the excellent performance of S-EB-S, it is also required that the 1,2-structure be evenly distributed in the mid-block polybutadiene B. This is because S-EB-S has the following structure: [0003] [0004] Ame...

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Problems solved by technology

The systems used in this patent include tetrahydrofuran / ethylene glycol dimethyl ether, tetrahydrofuran / diethylene glycol dimethyl ether, tetrahydrofuran / triethylene glycol dimethyl ether, tetrahydrofuran / hexamethylphosphoric triamide, tetrahydrofuran / tetramethyl However, due to the severe exothermic process of the anionic polymerization process using organolithium as the initiator, the temperature is difficult to control, so that the vinyl content in polybutadiene varies in a wide range

In other words, in the process of butadiene polymerization, as the molecular chain grows, the polymerization temperature gradually increases. After the temperature rises, the selectivity of the vinyl structure during polymerization will decrease. Low, high vinyl structure content, low butadiene content in late polymerization, if the polymerization temperature fluctuation exceeds 20 ° C, the difference in vinyl content in the butadiene chain may exceed 10%, resulting in product Defects

[0010] The content and distribution of vinyl groups in the polybutadiene chain can be controlled by adopting a single heavy ether in a continuous adding mode or first carrying out isothermal reaction and then carrying out adiabatic reaction, but studies have shown (Elastomer, 1999 No. 38): Ethers have a self-terminating effect in the polymerization system initiated by alkyllithium, that is, during the polymerization process, the ether will deactivate the active lithium and lead to the growth of the molecular chain, which will broaden the molecular weight distribution of the polymer, or oligomerization The content of the compound increases (the content of the oligomer is analyzed by gel permeation chromatography (GPC), which reduces the performance of the product

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