Kao Corporation

Kao Soap Company, Ltd.

Atsushi Sonobe

Masayuki Maruta

Shinichiro Yasuda

Yukiya Sato

Hisakazu Tajima

Eiji Morimoto

The developer composition for electrostatic latent images includes a toner and a carrier, the toner including (a) a binder resin comprising a polyester resin having an acid value of from 0 to 10 KOH mg/g; (b) a wax; and (c) a colorant. In the developer composition, the wax is dispersed in the toner with a length to diameter ratio of from 2 to 15.

Developer composition for electrostatic latent images

A new polyester resin is produced by condensation polymerization of (a) a diol component of the formula: ##STR1## wherein R.sup.1 is an alkylene group of 2 to 4 carbon atoms; and x and y are positive integers, the sum of them being 2 to 16 on an average, and (b) an acid component of polybasic (at least dibasic) carboxylic acid, anhydride thereof, and lower alkyl ester thereof, said acid component (b) containing 1 to 50 mol % of a dibasic carboxylic acid or anhydride thereof of the formula: ##STR2## where R.sup.2 and R.sup.3 are saturated or unsaturated hydrocarbon groups of 4 to 20 carbon atoms and 10 to 30 mol % of trimellitic acid or anhydride thereof. The polyester has improved toughness, abrasion resistance and flexibility.

Process for producing new polyester resin and product thereof

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Wakayama, Japan

Atsushi Sonobe