Processing fluid for image forming by aqueous ink, image forming method, recorded matter, and inkjet recording device

1. A processing fluid for image forming by an aqueous ink, the processing fluid comprising:

a flocculant configured to aggregate a colorant in the aqueous ink;

a water-soluble organic solvent;

a polymer particle; and

water,

wherein the polymer particle has a core-shell structure with a core portion including a wax and a shell portion having a lower critical solution temperature of 30 degrees C. or higher.

2. The processing fluid according to claim 1 , wherein the shell portion has a lower critical solution temperature of from 40 to 80 degrees C.

3. The processing fluid according to claim 1 , wherein the flocculant includes a water-soluble cationic polymer.

4. The processing fluid according to claim 3 , wherein the water-soluble cationic polymer has a quaternary ammonium cation in a main chain of the water-soluble cationic polymer.

5. The processing fluid according to claim 4 , wherein the water-soluble cationic polymer includes a repeating unit represented by the following chemical formula 1

where R1 and R2 each, independently represent alkyl groups having 1 to 8 carbon atoms, hydroxyalkyl groups having 1 to 8 carbon atoms, alkenyl groups having 2 to 8 carbon atoms, or benzyl groups.

6. An image forming method comprising:

applying the processing fluid of claim 1 to a recording medium;

discharging an aqueous ink to the recording medium by an inkjet method to form an image on the recording medium; and

drying the recording medium on which the image is formed by heat.

7. The image forming method according to claim 6 , wherein the recording medium has a coated layer on at least one surface of a substrate of the recording medium.

8. Recorded matter comprising:

a recording medium; and

an image recorded on the recording medium by the image forming method of claim 6 .

9. An inkjet recording device comprising:

the processing fluid of claim 1 ;

a conveyance unit to convey a recording medium in a conveyance direction;

a processing fluid applying device configured to apply the processing fluid to the recording medium;

an image forming device configured to discharge the aqueous ink to the recording medium by an inkjet method to form an image on the recording medium; and

a drier disposed downstream in the conveyance direction from the image forming device, to heat the recording medium bearing the image formed by the image forming device.