Patent ID: 8592120

Claim:
A resin for toner, the resin comprising a polyester resin (A) having a THF-insoluble fraction content of from 1 to 36% by weight, a peak top molecular weight of 4500 to 20000 as determined by gel permeation chromatography on a THF-soluble fraction and a softening point of 120 to 180° C., and meeting the requirements represented by the following mathematical formulae (1) and (2): Acid value/hydroxyl value ≧2 Formula (1) wherein the acid value is 15 to 80 mgKOH/g, and the hydroxyl value is 8.2 to 40 mgKOH/g; [A numeric value of the THF-insoluble fraction content expressed in % by weight ]/[a numeric value of the softening point expressed in degree ° C.]≦0.2 Formula (2); wherein the polyester resin (A) is reaction product of a polyester resin (a) having an acid value of 6.0 mgKOH/g or less and a hydroxyl value of from 10 to 70 mgKOH/g and at least one carboxylic acid (b) selected from the group consisting of divalent or higher valent aromatic carboxylic acids, acid anhydrides of these carboxylic acids, and alkyl C1-C4 alkyl esters of these carboxylic acids, wherein the polyester resin (a) is a polycondensate of at least one polyol component selected from the group consisting of polyalkylene ether glycols having 2 to 6 carbon atoms, alicyclic diols having 6 to 36 carbon atoms, adducts of alicyclic diols having 6 to 36 carbon atoms with alkylene oxides having 2 to 4 carbon atoms, adducts of bisphenols with alkylene oxides having 2 to 4 carbon atoms, and adducts of novolak resins with alkylene oxides having 2 to 4 carbon atoms and at least one polycarboxylic acid component selected from the group consisting of adipic acid, alkenyl succinic acids having 16 to 50 carbon atoms, terephthalic acid, isophthalic acid, maleic acid, fumaric acid, trimellitic acid, pyromellitic acid, acid anhydrides of these carboxylic acids and C1-C4 alkyl esters of these carboxylic acids.