Ink set for inkjet recording, and image recording method and image recording apparatus

Abstract

The ink set for inkjet recording includes: a first liquid which contains at least a water-soluble solvent, water, and pigment particles dispersed and retained in a medium including the water-soluble solvent and the water; and a second liquid which does not contain coloring material but contains at least a water-soluble solvent, water, and a liquid composition which enhances printing characteristics, wherein: an image is formed by making the first liquid and the second liquid come into contact with each other on a recording medium; and a ratio of pigment particles having a particle diameter of not less than 150 nm is not greater than 2 volume percent with respect to a whole of the pigment particles contained in the first liquid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The nature of this invention, as well as other objects and advantages 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 compositional diagram showing an inkjet recording apparatus forming an image forming apparatus according to an embodiment of the present invention;

FIGS. 2A and 2B are plan view perspective diagrams showing a compositional example of a print head;

FIG. 3 is a plan view perspective diagram showing another compositional example of a full-line type print head;

FIG. 4 is a cross-sectional diagram taken along line 4-4 in FIG. 2;

FIG. 5 is an enlarged diagram showing a nozzle arrangement of the print head shown in FIG. 2;

FIG. 6 is a general compositional diagram showing an ink supply system in the inkjet recording apparatus according to an embodiment of the present invention;

FIG. 7 is a principle block diagram showing system composition of the inkjet recording apparatus according to an embodiment of the present invention; and

FIG. 8 is an illustrative diagram showing a frame format of an image formation process in the inkjet recording apparatus according to an embodiment of the present invention.

Claims

1. An ink set for inkjet recording comprising: a first liquid which contains at least a water-soluble solvent, water, and pigment particles dispersed and retained in a medium including the water-soluble solvent and the water; anda second liquid which does not contain coloring material but contains at least a water-soluble solvent, water, and a liquid composition which enhances printing characteristics, wherein:an image is formed by making the first liquid and the second liquid come into contact with each other on a recording medium; anda ratio of pigment particles having a particle diameter of not less than 150 nm is not greater than 2 volume percent with respect to a whole of the pigment particles contained in the first liquid.

2. The ink set for inkjet recording as defined in claim 1, wherein the ratio is not greater than 1 volume percent.

3. The ink set for inkjet recording as defined in claim 1, wherein the ratio is not greater than 0.5 volume percent.

4. The ink set for inkjet recording as defined in claim 1, wherein at least one of the first liquid and the second liquid further comprises polymer microparticles.

5. The ink set for inkjet recording as defined in claim 4, wherein a glass transition temperature Tg of the polymer microparticles is not less than 30° C.

6. The ink set for inkjet recording as defined in claim 1, wherein: one of the first liquid and the second liquid is alkaline, and the other of the first liquid and the second liquid is acidic; andthe second liquid has an action of causing the pigment particles contained in the first liquid to aggregate when the first liquid and the second liquid come into contact with each other.

7. The ink set for inkjet recording as defined in claim 6, wherein: the liquid composition contained in the second liquid has an action of causing the pigment particles contained in the first liquid to aggregate; andthe liquid composition contains one of a polyvalent metallic salt and polyarylamine.

8. The ink set for inkjet recording as defined in claim 1, wherein an absolute value of a pH differential between the first liquid and the second liquid is not less than 3.0 and not greater than 5.5.

9. The ink set for inkjet recording as defined in claim 1, wherein the pigment particles are any one of C.I. Pigment Yellow 12, 17, 55, 74, 97, 120, 128, 151, 155 and 180.

10. The ink set for inkjet recording as defined in claim 1, wherein the pigment particles are any one of C.I. Pigment Red 122, C.I. Pigment Violet 19, C.I. Pigment Red 57:1 and 146, and C.I. Pigment Blue 15:3.

11. An ink unit in which at least black ink, cyan ink, magenta ink and yellow ink are taken as one unit, wherein all of the black ink, the cyan ink, the magenta ink and the yellow ink are constituted by the ink set for inkjet recording as defined in claim 1.

12. An image recording method using the ink set for inkjet recording as defined in claim 1, the image recording method including the steps of: applying the second liquid of the ink set to the recording medium; andapplying the first liquid of the ink set to the second liquid so that the first liquid and the second liquid come into contact with each other to form an image.

13. An image recording apparatus using the ink set for inkjet recording as defined in claim 1, the image recording apparatus comprising: a first application device which applies the second liquid of the ink set to the recording medium;a second application device which applies the first liquid of the ink set to the second liquid on the recording medium; anda heating device which heats an aggregate produced by contact between the first liquid and the second liquid.