Liquid developer, liquid developing device, and wet image forming method
In order to prevent the occurrence of bleeding in a nip between a photoreceptor and an intermediate transfer body or a nip between the photoreceptor and a sheet, which is a problem in a wet developing method, the present disclosure provides a liquid developer that includes an electrically insulating carrier liquid and colored particles dispersed within the carrier liquid, further contains an organic polymer compound, and has a viscosity of 30 to 400 mPa·s at a measurement temperature of 25° C.
1. A liquid developer comprising
an organic polymer compound dissolved in an electrically insulating carrier liquid that includes an oil selected from an aliphatic hydrocarbon, a vegetable oil, and a mixture thereof; and
a pigment dispersed within the carrier liquid,
wherein the organic polymer compound is selected from a cyclic olefin copolymer, a styrene elastomer, a cellulose ether, a polyvinyl butyral, and a mixture thereof;
wherein the liquid developer has a viscosity of 30 to 400 mPa·s at 25° C.
2. The liquid developer according to claim 1 , wherein a content of the organic polymer compound in the liquid developer is in the range of 1 to 10 mass %.
3. The liquid developer according to claim 1 , wherein the carrier liquid has a volume resistivity of 10 12 □·cm or above.
4. A liquid developing device that develops an electrostatic latent image formed on a surface of a photoreceptor drum using a liquid developer, comprising:
the photoreceptor drum; and
the liquid developer;
wherein the liquid developer comprises an organic polymer compound dissolved in an electrically insulating carrier liquid that includes an oil selected from an aliphatic hydrocarbon, a vegetable oil, and a mixture thereof; and a pigment dispersed within the carrier liquid; and
wherein the liquid developer has a viscosity of 30 to 400 mPa·s at 25° C.
5. A wet image forming method, comprising the steps of:
charging a surface of a photoreceptor drum;
forming an electrostatic latent image on the charged surface of the photoreceptor drum;
developing the electrostatic latent image on the surface of the photoreceptor drum by using a liquid developer that comprises an organic polymer compound dissolved in an electrically insulating carrier liquid that includes an oil selected from an aliphatic hydrocarbon, a vegetable oil, and a mixture thereof, and a pigment dispersed within the carrier liquid, and the liquid developer has a viscosity of 30 to 400 mPa·s at 25° C.;
transferring the developed image to a recording medium; and
discharging the recording medium having the image transferred thereto, from a discharge part.
6. The liquid developer according to claim 1 , wherein a content of the oil in the carrier liquid is in a range of 2 to 80 mass %.
7. The liquid developer according to claim 1 , wherein a content of the pigment in the liquid developer is in a range of 1 to 30 mass %.
8. The liquid developer according to claim 1 , wherein the pigment has a volume basis medium diameter (D 50 ) in a range of 0.1 to 1.0 □m.
9. The liquid developer according to claim 1 further comprising about 1 to 10 mass % of a dispersion stabilizer.
10. The liquid developer according to claim 1 , wherein the organic polymer is a styrene elastomer.
11. The liquid developer according to claim 10 , wherein the styrene elastomer is a block copolymer of an aromatic vinyl compound and a conjugated diene or olefinic compound.
12. The liquid developer according to claim 11 , wherein the styrene elastomer is a styrene-butadiene elastomer having a styrene block (polymer block A) and a butadiene block (polymer block B); wherein the styrene-butadiene elastomer has a content of polymer block A in a range from 5 to 75 mass %.
13. The liquid developer according to claim 1 , wherein the aliphatic hydrocarbon is a nonvolatile organic solvent.
14. The liquid developer according to claim 1 , wherein the aliphatic hydrocarbon is a low volatility organic solvent having a boiling point of 200° C. or higher.