Preparation method for polycarbonate-polydimethylsiloxane nano composite and use thereof in flame-retarding polycarbonate

Abstract

The invention relates to a preparation method for a polycarbonate-polydimethylsiloxane nano composite and use thereof in flame-retarding polycarbonate, and belongs to the technical field of flame-retarding material. The preparation method comprises: adding polydimethylsiloxane, diphenyl carbonate and magnesium chloride into a reactor; in a protective atmosphere of an inert gas, stirring the mixture, heating the mixture to perform a molten ester exchange reaction, and cooling the product after the reaction; adding bisphenol A, stirring and heating the mixture to perform polycondensation in protective atmosphere of an inert gas, and adding a nano material during polycondensation to obtain a final product; and adding the product into dichloromethane, washing the product with absolute ethanol, filtering the solution, drying the filter cake and obtaining the polycarbonate-polydimethylsiloxane nano composite. The polycarbonate-polydimethylsiloxane nano composite is environment-friendly flame-retarding polycarbonate and can reduce a peak heat release rate of polycarbonate.

Description

technical field [0001] The invention relates to a preparation method of polycarbonate-polydimethylsiloxane nanocomposite and its application in flame-retardant polycarbonate, belonging to the technical field of flame-retardant materials. Background technique [0002] Polycarbonate (PC) has high melt viscosity, difficult to process, difficult to make large-scale products, prone to stress cracking, and has poor solvent resistance, wear resistance, boiling water resistance, high temperature foaming; aging resistance is very poor Poor, due to hot air aging or hot water aging of transparent PC products during storage, processing and use, the performance deteriorates, such as reduced impact strength, product surface cracks, yellowing and loss of luster, which affects the normal use of its products . The thermal decomposition temperature of PC is high (310°C), and it has a certain flame retardancy (oxygen index is 24%). PC is self-extinguishing and emits carbon dioxide when burned...

AI Technical Summary

Problems solved by technology

However, the currently used phosphate ester has low hydrolysis stability and is volatile (mostly liquid), which reduces the thermal performance of the flame retardant material. In addition, the phosphate ester flame retardant PC is prone to stress cracking, transparency decreases, thermal stability deteriorates, and high temperature dimensions poor stability

Phosphazenes are flame retardant and contain phosphorus and nitrogen at the same time, and they are high-melting solids with good thermal stability. For example, the molecules contain reactive functional groups and can react with groups on PC, so they have been favored by people in recent years. Attention, in the past three years, there have been many patents on phosphazene as a PC flame retardant, but this type of flame retardant system is still in the development stage, some problems have yet to be resolved, and there may be the possibility of industrialization

(3) Sulfur-containing flame retardant PC, such as aromatic sulfonate (alkali metal or alkaline earth metal) and perfluoroalkyl sulfonate (combined with polytetrafluoroethylene), this technology has already been seen in the 1970s Early U.S. Patent (USP 3,775,367), but with variations in flame-retardant polycarbonate transparency and heat resistance

In addition, sulfonate can promote the decomposition of polycarbonate, which significantly reduces the thermal stability of flame-retardant polycarbonate

Moreover, there are inconsistent or unreliable flame retardant levels when used alone, and it needs to be used in conjunction with other flame retardants (such as halogens); at the same time, the mechanism of sulfonate flame retardant PC has not yet been fully understood.

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