Kao Corporation

Kao Soap Company, Ltd.

Eiji Morimoto

Shinichiro Yasuda

Kuniyasu Kawabe

Katsutoshi Aoki

Tetsuhiro Semura

Hidenori Tachi

Norihiro Hayashi

Atsushi Sonobe

Yuichi Ueda

A resin composition having a softening point of from 80&#xb0; to 165&#xb0; C., obtained by reacting a poly Calkylene terephthalate having a melting point of 200&#xb0; C. or more with a low-molecular weight polyester having a number-average molecular weight of from 400 to 2500; a resin binder for a toner comprising the above resin composition; a toner comprising the above resin binder; a process for preparing a resin composition having a softening point of from 80&#xb0; to 165&#xb0; C., comprising the step of reacting a poly Calkylene terephthalate having a melting point of 200&#xb0; C. or more with a low-molecular weight polyester having a number-average molecular weight of from 400 to 2500. The resin composition can be suitably used as a resin binder for a toner used for developing electrostatic latent images formed in electrophotography, electrostatic recording method, electrostatic printing, and the like.

Resin composition

A toner for electrophotography includes at least a binder resin and a colorant, the binder resin containing a linear polyester as a main component and having a pulverization index of from 14 to 40 obtained by a given method. A developer composition includes the above toner for electrophotography.

Toner for electrophotography and developer composition containing the

The present invention is directed to a toner composition containing a polyester resin as a major component of a binder resin and 0.01 to 1.5 parts by weight of hydrophobic silica having a degree of hydrophobic property of not less than 80, and/or having a pH value of 5.5 to 8 when 4% by weight of hydrophobic silica is dispersed in water-methanol solution (1:1) to 100 parts by weight of the toner.

Hydrophobic polyester toner composition

An electrophotographic developer composition, toner, comprises a binder of a polyester resin and a colorant, said polyeter resin having a softening point of 80.degree. to 180.degree. C., further having been obtained by copolycondensing (A) a diol component with (B) carboxylic acid components comprising (a) a dicarboxylic acid, (b) trimellitic acid and (c) a polycarboxylic acid. The composition possesses an improved fixation property.

Polyester resin, electrophotographic developer composition

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.

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Wakayama, Japan

Eiji Morimoto