Two-phase phase-transfer catalytic polymerization process of low molecular weight polystyrene

Abstract

The invention discloses a two-phase phase-transfer catalytic polymerization process of low molecular weight polystyrene. The two-phase phase-transfer catalytic polymerization process comprises the steps of: preparing raw materials; performing phase-transfer catalytic polymerization; separating; washing and the like. According to the process, a water-insoluble organic solvent and water are taken to be two-phase; a water-soluble initiator is adopted and is transferred to an organic phase under the action of a phase-transfer catalyst to initiate styrene polymerization; and the initiator and the phase-transfer catalyst in the polystyrene solution are removed through phase splitting and washing after the polymerization is finished to obtain pure polystyrene solution. The two-phase phase-transfer catalytic polymerization process has the advantages that: the polystyrene with low relative molecular weight and narrow molecular weight distribution can be prepared by using the process; the relative molecular mass of the polystyrene is 5,000-50,000; the prepared polystyrene basically contains no initiator; and thus, the alpha-site bromination in a bromination process is effectively avoided and the thermal stability of a product is obviously improved.

Description

technical field [0001] The invention relates to a low-molecular-weight polystyrene polymerization process, in particular to a low-molecular-weight polystyrene two-phase phase-transfer catalytic polymerization process, which belongs to the field of flame retardants. Background technique [0002] Brominated polystyrene (BPS for short) is an additive flame retardant for polymer materials. It has high bromine content, good flame retardant effect, good heat resistance, little impact on resin impact resistance, no The advantages of migration, low toxicity, environmental protection, and no release of carcinogens such as dioxins during combustion are fully in line with the European Union's "Restriction of the use of certain hazardous substances in electrical equipment" ("Restriction of the use of certain hazardous substances in electrical equipment") and electronic equipment" (referred to as the RoHS Directive) and "Waste Electrical and Electronic Equipment" (referred to as the WEEE...

AI Technical Summary

Problems solved by technology

But this method has the following two disadvantages: 1. the process has many operating procedures, long production cycle, high requirements for equipment conditions, large investment, and high price-performance ratio of products; 2. the existence of bromine makes double bonds difficult to polymerize, so this Method can only adopt dibromostyrene as raw material to produce dibromopolystyrene, and tribromostyrene cannot be adopted as raw material to produce tribromopolystyrene, thereby limiting the bromine content in bromopolystyrene (only 60%), and the unreacted monomer in brominated polystyrene-hardly volatile solid brominated styrene is difficult to remove

Since the initiator used is soluble in organic solvents and has a relatively high boiling point, the content of the initiator in the prepared polystyrene is relatively high, so that α-position bromination is easy to occur in the subsequent bromination process to make the product thermally stable. The property is reduced, as shown in the literature (Dong Shuan et al., Acta Functional Polymer Science, 1997, 10(1):87-89), the thermal weight loss of BPS prepared by this method exceeds 2% at 250°C