Ink Set and Inkjet Recording Method Using the Same and Recorded Article

Abstract

An ink set comprising at least a magenta ink composition and a light magenta ink composition having a pigment concentration lower than the pigment concentration of the magenta ink composition, wherein the pigment used in said magenta ink composition is C.I. pigment red 122 and the pigment used in said light magenta ink composition is C.I. pigment violet 19.

Description

EXAMPLES

The present invention is explained in detail below using examples. First, color ink compositions (inks Nos. 1-13) were prepared with the compositions and proportions shown in the following table. In the table, PV 19 signifies C.I. pigment violet 19, PR 122 is C.I. pigment red 122, PY 74 is C.I. pigment yellow 74, and PB 15:3 is C.I. pigment blue 15:3. BYK-348 is the silicon surfactant BYK-348 purchased from BYK-Chemie Japan.

[Table 1]

Using the aforementioned ink compositions (inks Nos. 1-13), ink sets A through K were configured with the combinations shown in the table below. The ink numbers used in this table correspond to the ink numbers used in Table 1.

[Table 2]

In ink set A (Example 1) and ink set B (Example 2), 6% by weight of C.I. pigment red 122 (PR 122) was used as the pigment in the magenta ink composition, while 1% by weight of C.I. pigment violet 19 (PV 19) was used as the pigment in the light magenta ink composition.

In ink set C (Example 3), 5.5% by weight of C.I. pigment red 122 (PR 122) was used as the pigment in the magenta ink composition, while 1.5% by weight of C.I. pigment violet 19 was used as the pigment in the light magenta ink composition.

In ink set D (Example 4), 6% by weight of C.I. pigment red 122 (PR 122) was used as the pigment in the magenta ink composition, while 1.5% by weight of C.I. pigment violet 19 (PV 19) was used as the pigment in the light magenta ink composition.

In ink set E (Example 5), 6% by weight of C.I. pigment red 122 (PR 122) was used as the pigment in the magenta ink composition, while 1.2% by weight of C.I. pigment violet 19 (PV 19) was used as the pigment in the light magenta ink composition.

In ink set F (Example 6), 6% by weight of C.I. pigment red 122 (PR 122) was used as the pigment in the magenta ink composition, while 1.8% by weight of C.I. pigment violet 19 (PV 19) was used as the pigment in the light magenta ink composition.

In ink set G (Example 7), 6% by weight of C.I. pigment red 122 (PR 122) was used as the pigment in the magenta ink composition, while 2.0% by weight of C.I. pigment violet 19 (PV 19) was used as the pigment in the light magenta ink composition.

In ink set H (Comparative Example 1), 6% by weight of C.I. pigment red 122 (PR 122) was used as the pigment in the magenta ink composition, while 1% by weight of C.I. pigment red 122 (PR 122) was used as the pigment in the light magenta ink composition.

In ink set I (Comparative Example 2), 6% by weight of C.I. pigment violet 19 (PV 19) was used as the pigment in the magenta ink composition, while 1% by weight of C.I. pigment violet 19 (PR 19) was used as the pigment in the light magenta ink composition.

In ink set J (Comparative Example 3), 6% by weight of C.I. pigment red 122 (PR 122) was used as the pigment in the magenta ink composition, and no light magenta ink composition was used.

In ink set K (Comparative Example 4), 6% by weight of C.I. pigment violet 19 (PV 19) was used as the pigment in the magenta ink composition, and no light magenta ink composition was used.

Test Example 1

Evaluation of Total Gamut Area (Color Reproducibility 1)

Total gamut area (that is, color reproducibility) was evaluated as follows using the ink sets A through K of the examples and comparative examples. Recorded material was obtained by printing using a PM-4000PX (Seiko-Epson) inkjet printer, specialized inkjet paper (Seiko-Epson, Premium Glossy Photo Paper) and a resolution of 1440×720. The single-color 100% duty was 13 mg/inch² and the mixed-color 120% duty was 16 mg/inch² for purposes of printing. Taking these as the maximum duty values, the duty value of each single-color ink was varied at intervals of 3% in the range of 0-100%, and all colors were printed reproducibly with the ink set by recombining all inks in the ink set.

Each color in each resulting printed material was measured with a calorimeter (Gretag Macbeth SPM50, viewing angle 2°, D50 light source), to obtain L*, a* and b* values according to CIE. Given a gamut area of 1 when all CIE values L*, a* and b* were 1, the total gamut area of each recorded material was calculated from the resulting L*, a* and b* values, and the following evaluation was based on the results. The evaluation results are shown together in Table 3 for the magenta ink composition and light magenta ink composition.

AA: Total gamut area of 750,000 or more
A:  Total gamut area of at least 740,000 and less than 750,000
B:  Total gamut area of at least 720,000 and less than 740,000
C:  Total gamut area of less than 720,000

Test Example 2

Evaluation of Total Gamut Area (Color Reproducibility 2)

Total gamut area (color reproducibility) was evaluated as in Test Example 1 except that printing was on specialized inkjet paper (Seiko-Epson, Premium Glossy Photo Paper) at a resolution of 720×720. The evaluation criteria were as follows. The evaluation results are shown together in Table 3 for the magenta ink composition and light magenta ink composition.

A: Total gamut area of 680,000 or more
B: Total gamut area of at least 650,000 and less than 680,000
C: Total gamut area of less than 650,000

Test Example 3

Color Reproducibility Evaluation of Bright Color Areas and Dark Color Areas (Color Reproducibility 3)

The gamut areas of bright color areas and dark color areas were evaluated as follows using the ink sets A through K of the examples and comparative examples. Patch patterns comprising a variety of hues with uniform, specific L* values were obtained by printing using a PM-4000 PX inkjet printer (Seiko-Epson) and each of ink sets A through K on specialized inkjet paper (Seiko-Epson Premium Glossy Photo Paper). The colors of the patch patterns of the respective ink sets were measured using a calorimeter (Gretag Macbeth SPM50).

Values (%) for bright color areas (L*=70) and dark color areas (L*=10) were calculated from the aforementioned measurement results using the color reproduction areas of ink set H and ink set I as standards (100%) for the bright color areas and dark color areas, respectively, and color reproducibility of the ink sets was evaluated according to the following criteria based on the resulting percentages. The evaluation results are shown together in Table 3 for the magenta ink composition and light magenta ink composition.

A: Over 105%
B: Over 100%, no more than 105%
C: 100%

Test Example 4

Evaluation of Color Development on Ordinary Paper

Color development on ordinary paper was evaluated as follows using the ink sets A through K of the examples and comparative examples. Xerox 4024 paper was used as the ordinary paper. Recorded material was obtained by printing using a PM-4000 PX (Seiko-Epson) printer loaded with each of ink sets A through K, with a mixed-color 100% duty and a resolution of 720×720.

The resulting recorded material was measured using a calorimeter (Gretag Macbeth SPM50, viewing angle 2°, D50 light source) to measure the concentration (OD value) of the magenta component of the mixed color. The evaluation criteria were as follows. The evaluation results are shown together in Table 3 for the magenta ink composition and light magenta ink composition.

A: 1.20 or more
B: 1.00 or more, less than 1.20
C: Less than 1.00

[Table 3]

Table 3 shows that the ink sets (A-G) of Examples 1 through 7 exhibit better color reproducibility than the ink sets (H-K) of Comparative Examples 1 through 4. In particular, there was an obvious difference between the examples and comparative examples in terms of color reproducibility at a resolution of 1440×720 (color reproducibility 1) and color reproducibility in bright color areas (color reproducibility 3).

As explained above, the present invention can provide an ink set having a wide range of color reproducibility from dark color areas through bright color areas, as well as an ink jet recording method and recorded material using that ink set.

TABLE 1
			Light
	Yellow	Cyan	Cyan	Magenta	Light Magenta	Black
Ink No.	1	2	3	4	5	6	7	8	9	10	11	12	13
PV 19 (weight %)				6.00			1.00		1.50	1.20	1.80	2.00
PR 122 (weight %)					6.00	5.50		1.00
PY 74 (weight %)	5.00
PB 15:3 (weight %)		4.00	1.00
Carbon black (weight %)													2.00
Dispersant (weight %)	1.50	1.20	0.30	1.80	1.80	1.60	0.30	0.30	0.50	0.40	0.60	0.70	0.60
Glycerin (weight %)	16.00	13.00	22.00	11.00	11.00	23.00	22.00	23.00	20.00	21.00	19.00	18.00	15.00
1,2-hexanediol	5.00	5.00	5.00	5.00	5.00	5.00	5.00	5.00	5.00	5.00	5.00	5.00	5.00
(weight %)
BYK-348 (weight %)	0.50	0.50	0.50	0.50	0.50	0.50	0.50	0.50	0.50	0.50	0.50	0.50	0.50
Triethanolamine	0.90	0.90	0.90	0.90	0.90	0.90	0.90	0.90	0.90	0.90	0.90	0.90	0.90
(weight %)
Pure water	Re-	Re-	Re-	Re-	Re-	Re-	Re-	Re-	Re-	Re-	Re-	Re-	Re-
	main-	main-	main-	main-	main-	main-	main-	main-	main-	main-	main-	main-	main-
	der	der	der	der	der	der	der	der	der	der	der	der	der
Total (%)	100	100	100	100	100	100	100	100	100	100	100	100	100

	TABLE 2
	Ink No.
			Light		Light
Ink set	Yellow	Cyan	Cyan	Magenta	Magenta	Black
A (Example 1)	1	2	3	5	7	—
B (Example 2)	1	2	3	5	7	13
C (Example 3)	1	2	3	6	9	13
D (Example 4)	1	2	3	5	9	13
E (Example 5)	1	2	3	5	10	13
F (Example 6)	1	2	3	5	11	13
G (Example 7)	1	2	3	5	12	13
H (Comparative	1	2	3	5	8	—
Example 1)
I (Comparative	1	2	3	4	7	—
Example 2)
J (Comparative	1	2	—	5	—	—
Example 3)
K (Comparative	1	2	—	4	—	—
Example 4)

	TABLE 3
	Color reproducibility 3
		Light	Color reproducibility 1	Color reproducibility 2	Bright	Dark	Ordinary paper
Ink set	Magenta	Magenta	(total gamut area)	(total gamut area)	color area	color area	color development
A (Example 1)	PR122	PV19	A	B	A	A	A
B (Example 2)	PR122	PV19	A	B	A	A	A
C (Example 3)	PR122	PV19	AA	A	AA	A	A
D (Example 4)	PR122	PV19	AA	A	AA	A	A
E (Example 5)	PR122	PV19	AA	A	AA	A	A
F (Example 6)	PR122	PV19	AA	A	AA	A	A
G (Example 7)	PR122	PV19	AA	A	AA	A	A
H (Comparative Example 1)	PR122	PR122	C	B	C	A	A
I (Comparative Example 2)	PV19	PV19	B	A	A	C	B
J (Comparative Example 3)	PR122	—	B	B	B	A	A
K (Comparative Example 4)	PV19	—	B	A	B	C	B

Claims

1. An ink set comprising at least a magenta ink composition and a light magenta ink composition having a pigment concentration lower than the pigment concentration of the magenta ink composition, wherein the pigment used in said magenta ink composition is C.I. pigment red 122 and the pigment used in said light magenta ink composition is C.I. pigment violet 19.

2. The ink set according to claim 1, wherein the ratio of the concentration of said C.I. pigment red 122 used in said magenta ink composition to the concentration of said C.I. pigment violet 19 used in said light magenta ink composition is between 4:3 and 14:1.

3. The ink set according to claim 1, wherein said magenta ink composition and said light magenta ink composition comprise a dispersant for dispersing the pigment.

4. The ink set according to claim 3, wherein said dispersant is a resin or surfactant.

5. The ink set according to claim 1, wherein said magenta ink composition and said light magenta ink composition comprise a penetrating agent for increasing penetration of the pigment into a recording medium.

6. The ink set according to claim 5, wherein said penetrating agent is a 1,2-alkanediol and/or a silicon surfactant.

7. The ink set according to claim 1, wherein said magenta ink composition and said light magenta ink composition comprise a wetting agent.

8. The ink set according to claim 7, wherein said wetting agent is a polyvalent alcohol.

9. The ink set according to claim 1, further comprising a yellow ink composition, a cyan ink composition and a light cyan ink composition.

10. An inkjet recording method in which printing is accomplished by discharging droplets of an ink composition and causing the droplets to adhere to a recording medium, wherein the ink set according to claim 1 is used.

11. A recorded material which is recorded using the ink set comprising at least a magenta ink composition and a light magenta ink composition having a pigment concentration lower than the pigment concentration of the magenta ink composition, wherein the pigment used in said magenta ink composition is C.I. pigment red 122 and the pigment used in said light magenta ink composition is C.I. pigment violet 19 or by the inkjet recording method according to claim 10.