Abstract: To provide polyphenylene ether with excellent solubility in general-purpose ketone solvents and its production method, and to provide a thermosetting composition, prepreg, and laminate using the polyphenylene ether. The polyphenylene ether includes a total of 100 mol % of a repeating unit derived from a phenol of Formula (1) and a repeating unit derived from a phenol of Formula (2), wherein from 5 mol % to 85 mol % is the repeating unit derived from the phenol of Formula (1) and from 15 mol % to 95 mol % is the repeating unit derived from the phenol of Formula (2), and a reduced viscosity (?sp/c) measured in chloroform solution at a concentration of 0.5 g/dL at 30° C. is from 0.03 dL/g to 0.30 dL/g.

Abstract: The present disclosure provides a polyphenylene ether composition having a high glass transition temperature and a long-term solubility in a solvent, and exhibiting a low viscosity when being dissolved in a solvent. The polyphenylene ether composition of the present disclosure contains 60 mol % or more of a polyphenylene ether having the structure of Formula (1), wherein the ratio of the integrated value of the peak appearing at 7.6 to 8.3 ppm to the integrated value of the peak derived from the structure of the following Formula (2) in a 1H-NMR measurement result is 1 or less, and the number average molecular weight in terms of polystyrene is 500 to 15,000 g/mol.

Abstract: Provided are a polyphenylene ether powder that exhibits low susceptibility to pulverization due to particle collisions, suppressed particle flushability, and excellent handleability, and a method for producing this polyphenylene ether powder. The polyphenylene ether powder includes one or more polyphenylene ether particles having an aspect ratio (DL/DS), expressing a ratio of a major axis diameter (DL) and a minor axis diameter (DS) of an individual particle, of 2.0 to 7.0.

Abstract: Provided are a polyphenylene ether powder that exhibits low susceptibility to pulverization due to particle collisions, suppressed particle flushability, and excellent handleability, and a method for producing this polyphenylene ether powder. The polyphenylene ether powder includes one or more polyphenylene ether particles having an aspect ratio (DL/DS), expressing a ratio of a major diameter (DL) and a minor diameter (DS) of an individual particle, of 2.0 to 7.0.