Composition comprising poly(2,6-dimethylphenylene) ether

1. A polyphenylene ether resin composition comprising a polyphenylene ether and a styrene polymer resin,

the content of said polyphenylene ether in said composition being from 10 to 90% by weight,

said polyphenylene ether having a polymer chain comprising recurring units each represented by the following formula (1):

said composition being characterized in that the polyphenylene ether, when isolated from the composition and purified, has the following characteristics (a), (b) and (c):

(a) when dissolved in deuterated chloroform and analyzed by proton nuclear magnetic resonance spectroscopy ( 1 H-NMR) using tetramethylsilane as a reference for chemical shift, said isolated and purified polyphenylene ether exhibits a triplet signal (S 1 ) at 3.55 ppm, said triplet signal (S 1 ) having a relative intensity of 0.05 to 0.25 in terms of the percentage of the integrated intensity of said triplet signal (S 1 ), based on the integrated intensity of a signal (S 2 ) observed at 6.47 ppm;

(b) when a 0.05 g/ml solution of said isolated and purified polyphenylene ether in chloroform is analyzed by ultraviolet-visible spectroscopy using a cell having an optical path of 1 cm, said polyphenylene ether exhibits an absorbance of from 0.01 to 0.40 at a wavelength of 480 nm; and

(c) said isolated and purified polyphenylene ether has a weight average molecular weight of from 30,000 to 100,000 as measured by gel permeation chromatography using a calibration curve obtained with respect to standard monodisperse polystyrene samples.

2. The polyphenylene ether resin composition according to claim 1 , wherein, in the curve obtained by subjecting said composition to differential scanning calorimetry, the amount of heat absorbed by said polyphenylene ether is not more than 0.1 J/g, as defined by the area of an endothermic peak ascribed to said polyphenylene ether, said endothermic peak being observed in the range of from 230 to 270° C.

3. The polyphenylene ether resin composition according to claim 1 , which has a volatile component content of 2% by weight or less.

4. The polyphenylene ether resin composition according to claim 1 , wherein said relative intensity of said triplet signal (S 1 ) in the 1 H-NMR is from 0.05 to 0.15, and said absorbance in the ultraviolet-visible spectroscopy is from 0.01 to 0.30.

5. The polyphenylene ether resin composition according to claim 1 , which is produced by melt-kneading a mixture comprising a raw material polyphenylene ether and a styrene polymer resin at a temperature of from 240 to 390° C. for a residence time of from 25 to 300 sec,

said raw material polyphenylene ether being produced by feeding a solution of 2,6-dimethylphenol to a reactor having been charged with a liquid mixture, while introducing an oxygen-containing gas to said reactor, thereby performing oxidative polymerization of 2,6-dimethylphenol,

wherein said solution of 2,6-dimethylphenol fed to said reactor is obtained by dissolving 2,6-dimethylphenol in a mixture of toluene and dimethyl-n-butylamine,

wherein said liquid mixture charged to said reactor contains toluene and a polymerization catalyst which contains cuprous oxide, an aqueous solution of hydrogen bromide, di-n-butylamine, dimethyl-n-butylamine, N,N′-di-t-butylethylenediamine and trioctylmethylammonium chloride,

wherein the amount of 2,6-dimethylphenol fed to said reactor is 13% by weight, based on the total weight of said solution fed to said reactor and said liquid mixture charged to said reactor.