VALLEY FORGE, Pa. - JPMorgan Chase & Co.'s private equity arm, JPMorgan Partners, said it would buy PQ Corp., a privately held chemicals company. JPMorgan declined to disclose terms of the deal. PQ, a family-run business based in Berwyn, Pa., has projected 2004 sales of $600 million. Its main product is silicates, glassy materials used in highway paint among other uses.