| 摘要 |
PROBLEM TO BE SOLVED: To obtain a polyester composition which particularly shows excellent abrasion resistance and durability, when it is used as a magnetic tape base by adding a slurry prepared by wet-treating 2 or more kinds of aluminum oxide particles different in their crystalline structure. SOLUTION: When polyester is produced using the acid components mainly containing aromatic dicarboxylic acids and the glycol components mainly containing aliphatic glycol, a slurry which is prepared by wet-dispersing two or more kinds of aluminum oxides different in their crystalline structure (suitably particles of 2 or more kinds of activated alumina selected fromα-,γ-,δ-,θ-aluminum oxides) in a solvent (preferably the above-stated glycol component) using a phosphorus compound, preferably phosphoric acid, ammonia or a lower amine as a dispersant is added to the polyester at any optional stage. The aluminum oxide particles preferably have a specific surface area of 50-300m<2> /g and the total pore volume of 0.2-1.5ml/g both according to the B.E.T. method.
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