Prepn. method of double-functionality lithium system initiator

Abstract

The present invention proposes a preparation method of a bifunctional lithium-based initiator, in which metal lithium reacts with α-methylstyrene or isoprene in a mixed solvent mainly composed of non-polar solvents to directly prepare a difunctional anion Polymer. The mixed solvent is mainly aromatic hydrocarbons or alkanes, or a mixture of the two, containing ethers or amines, or a mixture of the two, wherein the content of aromatic hydrocarbons and alkanes is 50-99.9% (volume), and the content of ethers and amines is 0.1-50%. (volume), conjugated olefin and metal lithium are reacted at a temperature of -50 to 50° C. for 1 to 6 hours, and the reactant is filtered to obtain a bifunctional initiator. The initiator prepared by this method does not contain fused-ring aromatic hydrocarbons, and the content of polar substances in the initiator system can be adjusted in a wide range. It can be used for the synthesis of polydiene series rubbers with low side group content, and has good stability and moderate reaction speed. specialty.

Description

Technical field: [0001] The invention relates to a preparation method of an initiator for synthesizing polymers by anion method. Especially for the preparation of bifunctional lithium initiators for the synthesis of block copolymers or telechelic polymers. Background technique: [0002] Alkali metals and fused-ring aromatics can form homogeneous complexes in ether solvents. The complexes are highly active and can react with dienes or styrene monomers to generate difunctional anion initiators. However, the complexes The formation reaction speed and maximum concentration of methionine increase according to the polarity of the solvent, so polar ether molecules such as tetrahydrofuran (THF) and dimethoxyethane (DMF) must be used as solvents for preparation and storage. The existence of a large number of polar molecules will have the following negative effects: 1. The side group content of the conjugated diene polymer is too large, the glass transition temperature will increase,...

AI Technical Summary

Problems solved by technology

The existence of a large number of polar molecules will have the following negative effects: 1. The side group content of the conjugated diene polymer is too large, the glass transition temperature will increase, and the performance requirements of rubber will not be met.

2. Polar solvents are more expensive, resulting in an increase in the cost of the initiator

3. The initiator is unstable and has negative reactions

Although this method excludes polycyclic aromatic hydrocarbon compounds, the complicated distillation process has become an obstacle to its practical application.