Image forming apparatus and image forming method

Abstract

The image forming apparatus includes: an intermediate transfer body; a liquid adhesion device which provides a first liquid having a viscosity not less than 15 mPa·s and not greater than 300 mPa·s at 25° C, on the intermediate transfer body; a droplet ejection device which ejects a second liquid containing a coloring material onto a region of the intermediate transfer body where the first liquid is provided by the liquid adhesion device, in a state where the first liquid on the intermediate transfer body has a thickness not less than 1.6 μm; a viscosity raising device which raises a viscosity of the second liquid on the intermediate transfer body; and a transfer device which transfers an image including dots of the second liquid formed on the intermediate transfer body, onto a recording medium.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The nature of this invention, as well as other objects and benefits thereof, will be explained in the following with reference to the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures and wherein:

FIG. 1 is a general schematic drawing of an inkjet recording apparatus according to an embodiment of the present invention;

FIG. 2 is a diagram showing a state of treatment liquid and ink droplets deposited on an intermediate transfer body;

FIG. 3 is a principal plan diagram of the peripheral area of a print unit in the inkjet recording apparatus shown in FIG. 1;

FIGS. 4A to 4C are plan view perspective diagrams showing embodiments of the composition of a print head;

FIG. 5 is a diagram showing a cross-sectional view along line 5-5 in FIGS. 4A and 4B;

FIG. 6 is a schematic diagram showing the composition of a supply system in the inkjet recording apparatus shown in FIG. 1;

FIG. 7 is a principal block diagram showing the system configuration of the inkjet recording apparatus shown in FIG. 1;

FIG. 8 is a diagram showing the degree of depositing interference depending on the thickness of the treatment liquid;

FIG. 9 is a diagram showing the degree of depositing interference depending on the viscosity of the treatment liquid;

FIG. 10 is a diagram showing the degree of depositing interference depending on the relationship between the dynamic surface tensions of the treatment liquid and the ink;

FIG. 11 is a diagram showing the relationship between the ink viscosity and the transfer rate;

FIG. 12 is a general compositional diagram of an inkjet recording apparatus according to a second embodiment of the present invention;

FIG. 13 is a general compositional diagram of an inkjet recording apparatus according to a third embodiment of the present invention;

FIG. 14 is a general schematic drawing of an inkjet recording apparatus according to an adaptation embodiment of the present invention;

FIG. 15 is a general compositional diagram of an inkjet recording apparatus according to a further adaptation embodiment of the present invention; and

FIG. 16 is a diagram showing depositing interference in an inkjet recording apparatus in the related art.

Claims

1. An image forming apparatus comprising: an intermediate transfer body;a liquid adhesion device which provides a first liquid having a viscosity not less than 15 mPa·s and not greater than 300 mPa·s at 25° C., on the intermediate transfer body;a droplet ejection device which ejects a second liquid containing a coloring material onto a region of the intermediate transfer body where the first liquid is provided by the liquid adhesion device, in a state where the first liquid on the intermediate transfer body has a thickness not less than 1.6 μm;a viscosity raising device which raises a viscosity of the second liquid on the intermediate transfer body; anda transfer device which transfers an image including dots of the second liquid formed on the intermediate transfer body, onto a recording medium.

2. The image forming apparatus as defined in claim 1, wherein relationship between a dynamic surface tension γ1 at a surface age of 0.1 sec of the first liquid and a dynamic surface tension γ2 at a surface age of 0.1 sec of the second liquid satisfies a following relationship: γ1<γ2.

3. The image forming apparatus as defined in claim 1, wherein the droplet ejection device comprises a full line liquid ejection head having a nozzle row in which nozzles ejecting the second liquid are arranged through a length corresponding to a breadth of the intermediate transfer body.

4. The image forming apparatus as defined in claim 1, wherein: the second liquid contains a radiation-curable polymerizable compound; andthe viscosity raising device comprises a radiation irradiation device.

5. The image forming apparatus as defined in claim 1, wherein: the second liquid contains a radiation-curable polymerizable compound;the intermediate transfer body has a hollow round cylindrical shape;the viscosity raising device comprises a radiation irradiation device which is arranged inside the intermediate transfer body and which irradiates the second liquid on the intermediate transfer body with a radiation; andat least a portion of the intermediate transfer body which is irradiated with the radiation by the radiation irradiation device is composed of a member which transmits the radiation.

6. The image forming apparatus as defined in claim 1, wherein: the second liquid contains an ultraviolet-curable polymerizable compound;at least one of the first liquid and the second liquid contains a polymerization initiator; andthe viscosity raising device comprises an ultraviolet light irradiation device.

7. The image forming apparatus as defined in claim 1, wherein the viscosity raising device raises the viscosity of the second liquid on the intermediate transfer body to not less than 5000 mPa·s.

8. The image forming apparatus as defined in claim 1, further comprising a main curing device which performs main curing of the image on the recording medium.

9. The image forming apparatus as defined in claim 1, wherein the transfer device comprises a heating device which heats the dots of the second liquid to a temperature not less than a glass transition temperature of the second liquid.

10. An image forming method for forming an image on an intermediate transfer body and transferring the image from the intermediate transfer body onto a recording medium, the image forming method including the steps of: providing a first liquid having a viscosity not less than 15 mPa·s and not greater than 300 mPa·s at 25° C., on the intermediate transfer body;ejecting a second liquid containing a coloring material onto a region of the intermediate transfer body where the first liquid is provided, in a state where the first liquid has a thickness not less than 1.6 μm on the intermediate transfer body;raising a viscosity of the second liquid on the intermediate transfer body; andtransferring the image including dots of the second liquid formed on the intermediate transfer body, onto the recording medium.

11. The image forming method as defined in claim 10, wherein: the viscosity of the second liquid on the intermediate transfer body is raised by curing the second liquid; andthe image is transferred onto the recording medium while the second liquid that has been cured is heated to a temperature not less than a glass transition temperature of the second liquid.

12. The image forming method as defined in claim 10, wherein the viscosity of the second liquid on the intermediate transfer body is raised to not less than 5000 mPa·s.