1. Field of the Invention
This invention relates to a resin composition having a high impact resistance.
2. Description of the Prior Art
Bisphenols the nucleus of which is substituted with a halogen, particularly, tetrabromobisphenol A, are known to be flame retarding agents. The incorporation of tetrabromobisphenol A in various synthetic resins to obtain flame-retardant resin compositions has been proposed. In one process tetrabromobisphenol A is copolymerized with halogen-free bisphenol such as bisphenol A to improve the flame-retardant property of a polycarbonate resin derived from bisphenol A. In addition, it has been proposed to obtain a flame-retardant resin composition by incorporating said copolymerized polycarbonate into a polycarbonate resin derived from bisphenol A (Japanese Patent Publication No. 24660/1972).
However, a copolymer composition containing such a copolymerized polycarbonate particularly derived from more than 2 mole percent of a nuclear-halogen-substituted bisphenol, is brittle because of the very low impact strength thereof as shown in FIG. 1. In addition, practical limitations occur such as the need for using a higher temperature in the molding because of its reduced melt fluidity.
Therefore, for improving the molding property of the polycarbonate resin, there has been proposed a process wherein a nuclear-halogen-substituted bisphenol A is incorporated therein, or a process wherein a low molecular weight polycarbonate (generally having a polymerization degree of about 2 to 10) derived from a nuclear-halogen-substituted bisphenol is incorporated therein (Japanese Patent Publications Nos. 41422/1972 and 44537/1972). It is impossible, by either of those prior processes, however, to prevent impairment of the physical properties of the resin generally caused by the incorporation of the low molecular weight materials, and it is difficult to retain well-balanced physical properties such as mechanical strength and molding property, even though flame-retardance can be imparted thereto.