Polyester resin for toner, method for producing same and toner

Abstract

Disclosed is a toner which is excellent in low-temperature fixability, high-temperature offset resistance, storage stability and durability, while having a wide range of fixing temperature. Also disclosed is a polyester resin used for such a toner. The polyester resin is one of the following polyester resin (A)-(E) for toners. (A) A polyester resin for toners having an Mp as determined by GPC of not less than 12,000 and having an unsaturated double bond (B) A polyester resin for toners obtained by crosslinking the polyester resin (A) (C) A polyester resin for toners containing the polyester resin (A) and another polyester resin having an Mp as determined by GPC of less than 12,000 (D) A polyester resin for toners obtained by crosslinking the polyester resin (C) (E) A polyester resin for toners containing a THF soluble fraction and a THF insoluble fraction wherein the Mw/Mn of the THF soluble fraction is not less than 6 and the total of the acid value and the hydroxyl value of the THF insoluble fraction is not more than 40 mgKOH/g.

1 . A polyester resin for toner (1) with a peak molecular weight of at least 12,000 in gel permeation chromatography and containing an unsaturated double bond. 
   
   
       2 . A polyester resin for toner obtained by crosslinking reaction of polyester resin for toner (1) with a peak molecular weight of at least 12,000 in gel permeation chromatography and containing an unsaturated double bond. 
   
   
       3 . A polyester resin for toner comprising polyester resin for toner (1) with a peak molecular weight of at least 12,000 in gel permeation chromatography and containing an unsaturated double bond, and polyester resin for toner (2) with a peak molecular weight of less than 12,000 in gel permeation chromatography. 
   
   
       4 . A polyester resin for toner obtained by crosslinking reaction of a polyester resin for toner comprising polyester resin for toner (1) with a peak molecular weight of at least 12,000 in gel permeation chromatography and containing an unsaturated double bond, and polyester resin for toner (2) with a peak molecular weight of less than 12,000 in gel permeation chromatography. 
   
   
       5 . A polyester resin for toner comprising a THF-soluble fraction and a THF-insoluble fraction, wherein the ratio of the mass-average molecular weight (Mw)/number-average molecular weight (Mn) (Mw/Mn) of the THF-soluble fraction is 6 or greater and the sum of the acid value and hydroxyl value of the THF-insoluble fraction is no greater than 40 mgKOH/g. 
   
   
       6 . A toner obtained by melt kneading a polyester resin for toner according to any one of  claims 1  to  5 , a release agent and a coloring agent. 
   
   
       7 . A process for production of a polyester resin for toner comprising blending and crosslinking polyester resin for toner (1) with a peak molecular weight of at least 12,000 in gel permeation chromatography and containing an unsaturated double bond, and polyester resin for toner (2) with a peak molecular weight of less than 12,000 in gel permeation chromatography.