# US 8,465,900 B2 · Electrophotographic toner

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- Number: US 8,465,900 B2
- Document ID: US8465900B2
- Status: Granted
- Kind: B2
- Application number: 12/912,343
- Filed: 2010-10-26
- Published: 2011-04-28
- Granted: 2013-06-18
- Earliest claimed: 2009-10-27
- Assignees: Sharp Kabushiki Kaisha
- Applicants: Masahiko Kubo
- Inventors: Masahiko Kubo
- Web page: https://patentgrep.com/patent/US8465900B2

## CPC

- G03G 15/201: {of high intensity and short duration, i.e. flash fusing}
- G03G 9/08755: {Polyesters}
- G03G 9/08795: {characterised by their chemical properties, e.g. acidity, molecular weight, sensitivity to reactants}
- G03G 9/08797: {characterised by their physical properties, e.g. viscosity, solubility, melting temperature, softening temperature, glass transition temperature}
- G03G 9/09: Colouring agents for toner particles
- G03G 9/0906: {Organic dyes}
- G03G 9/0926: {characterised by physical or chemical properties}
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

The present invention provides an electrophotographic toner comprising a polyester resin as binder resin and a colorant, said polyester resin being the condensation product of at least one polyhydric alcohol with at least one polybasic acid, wherein said at least one polyhydric alcohol comprises cyclohexanedimethanol, said toner having a loss modulus of from 2×103 Pa to 3×104 Pa at 110° C. and being irradiated with only laser light for fixing. According to toner of the invention, high quality toner images can be fixed with desired fastness and without white spots.

## Claims

### Claim 1

A fixing process for electrophotography, comprising the steps of: fusing a toner forming an unfixed toner image on a recording medium by irradiation with a laser light beam, wherein said toner is the toner comprising a polyester resin as binder resin and a colorant, said polyester resin being the condensation product of at least one polyhydric alcohol with at least one polybasic acid, wherein said at least one polyhydric alcohol comprises cyclohexanedimethanol, said toner having a loss modulus of from 2×103 Pa to 3×104 Pa at 110° C. and being irradiated with only laser light for fixing, said toner further having a tan δ of not less than 8 nor more than 20 at 110° C., where the tan δ is a ratio of a loss modulus to a storage modulus, said laser light beam having a wavelength within an absorption band of the colorant contained in said toner; and fixing said toner image onto said recording medium by re-solidifying said toner.

### Claim 2 (depends on 1)

The process of claim 1, wherein said polyhydric alcohol further comprises a bisphenol A alkylene oxide adduct.

### Claim 3 (depends on 1)

The process of claim 1, wherein said colorant is selected from the group consisting of cyan, magenta and yellow pigments and dyes.

### Claim 4 (depends on 1)

The process of claim 1, wherein the toner does not substantially comprise an infrared-absorbent.

### Claim 5

A fuser unit for electrophotography, comprising a laser light source for emitting a laser light beam to an unfixed toner image on a recording medium, thereby heat-fusing a toner forming said toner image, wherein said toner comprising a polyester resin as binder resin and a colorant, said polyester resin being the condensation product of at least one polyhydric alcohol with at least one polybasic acid, wherein said at least one polyhydric alcohol comprises cyclohexanedimethanol, said toner having a loss modulus of from 2×103 Pa to 3×104 Pa at 110° C. and being irradiated with only laser light for fixing, said toner further having a tan δ of not less than 8 nor more than 20 at 110° C., where the tan δ is a ratio of a loss modulus to a storage modulus, and said laser light beam has a wave length within an absorption band of the colorant contained in said toner.

### Claim 6 (depends on 5)

The fuser unit according to claim 5, which does not comprise a non-laser light source for irradiating a toner forming said toner image.

### Claim 7 (depends on 5)

An electrophotographic image-forming apparatus using an electrophotographic developer comprising said toner and comprising the fuser unit according to claim 5.