| 摘要 |
PROBLEM TO BE SOLVED: To provide a pentaerythritol diphosphonate compound having characteristics capable of inhibiting the reduction of strength of a resin which becomes a big problem on mixing the same with the resin, and imparting a high flame retardant property by an industrially advantageous method excellent in productivity. SOLUTION: This cyclic phosphonate compound is expressed by formula 1 [wherein, Ar<SP>1</SP>and Ar<SP>2</SP>are each the same or different and are each a 6-20C (substituted) aryl; R<SP>1</SP>to R<SP>4</SP>are each the same or different and are each H, a 6-20C (substituted) aryl or a 1-20C saturated or unsaturated hydrocarbon], and has≤0.7 mg acid value per 1g of the compound based on KOH. COPYRIGHT: (C)2004,JPO
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