Ink set comprising dark yellow ink composition

Claim 2

1 . An ink set comprising at least a normal yellow ink composition and a dark yellow ink composition, the lightness of the dark yellow ink composition being lower than that of the normal yellow ink composition.

Claim 3

2 . The ink set according to claim 1 , wherein the lightness of the ink composition is the lightness of an L*a*b* color system as calculated from the spectral characteristics of a 1000-fold dilution of the ink composition with water.

Claim 4

3 . The ink set according to claim 2 , wherein the difference in lightness between the normal yellow ink composition and the dark yellow ink composition is 10 to 70.

Claim 5

4 . The ink set according to claim 2 , wherein the dark yellow ink composition has a lightness of 20 to 90.

Claim 6

5 . The ink set according to claim 2 , wherein the normal yellow ink composition has a lightness of not less than 90.

Claim 7

6 . The ink set according to claim 1 , wherein the lightness of the ink composition is the lightness of an L*a*b* color system as calculated from the spectral characteristics of a record produced by evenly impacting the ink composition at 1.48 to 2.22 mg/cm 2 into a recording medium having a whiteness W of not less than 90 as measured according to JIS Z 8715.

Claim 8

7 . The ink set according to claim 6 , wherein the lightness of the ink composition is calculated at a level of ink impaction into the recording medium of 1.85 mg/cm 2 .

Claim 9

8 . The ink set according to claim 6 , wherein the difference in lightness between the normal yellow ink composition and the dark yellow ink composition is 20 to 70.

Claim 10

9 . The ink set according to claim 1 , wherein, for the dark yellow ink composition, the absolute value of b*/a* in the L*a*b* color system as calculated from the spectral characteristics of a 1000-fold dilution of the dark yellow ink composition with water is not less than 0.83 and the b* value is not less than zero (0).

Claim 11

10 . The ink set according to claim 9 , wherein the b* value of the dark yellow ink composition is smaller than the b* value of the normal yellow ink composition as calculated from the spectral characteristics of a 1000-fold dilution of the normal yellow ink composition with water.

Claim 12

11 . An ink set comprising at least a normal yellow ink composition and a dark yellow ink composition, wherein for the dark yellow ink composition, the absolute value of b*/a* in the L*a*b* color system as calculated from the spectral characteristics of a 1000-fold dilution of the dark yellow ink composition with water is not less than 0.83, and the b* value is not less than zero (0) and is smaller than the b* value of the normal yellow ink composition as calculated from the spectral characteristics of a 1000-fold dilution of the normal yellow ink composition with water.

Claim 13

11 . An ink set comprising at least a normal yellow ink composition and a dark yellow ink composition, wherein for the dark yellow ink composition, the absolute value of b*/a* in the L*a*b* color system as calculated from the spectral characteristics of a 1000-fold dilution of the dark yellow ink composition with water is not less than 0.83, and the b* value is not less than zero (0) and is smaller than the b* value of the normal yellow ink composition as calculated from the spectral characteristics of a 1000-fold dilution of the normal yellow ink composition with water.

Claim 14

12 . The ink set according to claim 10 , wherein the difference in b* value between the normal yellow ink composition and the dark yellow ink composition is not less than 20.

Claim 15

13 . The ink set according to claim 12 , wherein the absolute value of b*/a* of the normal yellow ink composition is not less than 1.73.

Claim 16

14 . The ink set according to claim 12 , wherein the absolute value of b*/a* of the normal yellow ink composition is not less than 1.73 and the b* value is not less than 50.

Claim 17

15 . The ink set according to claim 10 , wherein the b* value of the dark yellow ink composition is in the range of 10 to 50 while the b* value of the normal yellow ink composition is in the range of 60 to 90.

Claim 18

16 . The ink set according to claim 1 , wherein the absolute value of b*/a* in the L*a*b* color system of the dark yellow ink composition as calculated from the spectral characteristics of a record produced by evenly impacting the ink composition into a recording medium having a whiteness W of not less than 90 at 1.48 to 2.22 mg/cm 2 is not less than 0.83 and the b* value is not less than zero (0).

Claim 19

17 . The ink set according to claim 16 , wherein the absolute value of b*/a* and the b* value are calculated at a level of ink impaction into the recording medium of 1.85 mg/cm 2 .

Claim 20

18 . The ink set according to claim 16 , wherein the b* value of the dark yellow ink composition is smaller than the b* value of the normal yellow ink composition.

Claim 21

19 . The ink set according to claim 18 , wherein the difference in b* value between the normal yellow ink composition and the dark yellow ink composition is not less than 30.

Claim 22

20 . The ink set according to claim 19 , wherein the absolute value of b*/a* of the normal yellow ink composition is not less than 1.73.

Claim 23

21 . The ink set according to claim 1 , wherein the dark yellow ink composition, when spectroscopically analyzed on a 1000-fold dilution thereof with water, has at least one absorption maximum in the wavelength range of 350 to 500 nm.

Claim 24

22 . The ink set according to claim 21 , wherein, in the spectroscopic analysis of a 1000-fold dilution of the dark yellow ink composition with water, the absorption maximum value in the wavelength range of 350 to 500 nm is larger than that in the wavelength range of 500 to 780 nm.

Claim 25

23 . The ink set according to claim 21 , wherein, in the spectroscopic analysis of a 1000-fold dilution of the dark yellow ink composition with water, the integration value of the spectral characteristics in the wavelength range of 350 to 500 nm is 1.5 to 10 times the integration value of the spectral characteristics in the wavelength range of 500 to 780 nm.

Claim 26

24 . The ink set according to claim 1 , wherein the dark yellow ink composition comprises, as colorants, at least one first colorant selected from the group consisting of compounds represented by formula (I) and (II) wherein R 1 , R 1 ′, R 2 , and R 2 ′ each independently represent CH 3 or OCH 3 ; and A and A′ each independently represent a group having a structure selected from the group consisting of wherein M represents hydrogen, lithium, sodium, potassium, ammonium, or an organic amine; and n is an integer of 1 or 2, and at least one second colorant selected from the group consisting of magenta, cyan, and black dyes.

Claim 27

25 . The ink set according to claim 24 , wherein the first colorant is selected from the group consisting of C.I. Direct Yellow 50, C.I. Direct Yellow 55, C.I. Direct Yellow 86, C.I. Direct Yellow 132, and C.I. Direct Yellow 173.

Claim 28

26 . The ink set according to claim 24 , wherein the second colorant is selected from the group consisting of: magenta dyes selected from compounds represented by formula (III) wherein M represents hydrogen, lithium, sodium, potassium, ammonium, or an organic amine, and R 3 represents chlorine or a group represented by formula wherein X represents an anilino group substituted by at least one SO 3 M, and Y represents OH, chlorine, or a morpholino group, R 4 represents hydrogen, chlorine, SO 3 M, or a C 1 -C 4 alkyl group, or compounds represented by formula (IV) wherein α represents a C 1 -C 4 alkyl or alkoxy group or an OH—, SO 3 H—, or COOM-substituted phenyl or naphthyl group, β represents hydrogen or a group represented by formula wherein R 5 represents hydrogen or an OH— or COOH-substituted C 1 -C 4 alkyl group, R 6 represents an OH—, OCH 3 —, OC 2 H 5 —, SO 3 M—, or COOM-substituted C 1 -C 4 alkyl or phenyl group, R 7 represents OH, COOH, or NHR 8 , and R 8 represents an SO 3 M— or COOH-substituted C 1 -C 4 alkyl group, M represents hydrogen, lithium, sodium, potassium, ammonium, or an organic amine; cyan dyes selected from compounds represented by formula (V) wherein R 9 represents OH, COOM, or R 10 COOM wherein R 10 represents C 4 -C 9 alkyl group, and l, m, and n are each 0 to 4, provided that (l+m+n)=4; and black dyes selected from C.I. Direct Black 195, C.I. Food Black 2, C.I. Sulfur Black 1, or C.I. Reactive Black 31 or C.I. Reactive Black 35.

Claim 29

27 . The ink set according to claim 1 , wherein the dark yellow ink composition comprises, as colorants, at least one first colorant selected from the group consisting of C.I. Pigment Yellow 74, C.I. Pigment Yellow 93, C.I. Pigment Yellow 109, C.I. Pigment Yellow 110, C.I. Pigment Yellow 128, C.I. Pigment Yellow 138, C.I. Pigment Yellow 150, C.I. Pigment Yellow 151, C.I. Pigment Yellow 154, C.I. Pigment Yellow 155, C.I. Pigment Yellow 180, and C.I. Pigment Yellow 185, and at least one second colorant selected from the group consisting of C.I. Pigment Blue 15:3, C.I. Pigment Blue 15:4, C.I. Pigment Blue 60, C.I. Pigment Red 122, C.I. Pigment Red 202, C.I. Pigment Red 209, C.I. Pigment Violet 19, and carbon black.

Claim 30

28 . The ink set according to claim 27 , wherein the content of the first colorant in the dark yellow ink composition is 0.1 to 10% by weight and the content of the second colorant in the dark yellow ink composition is 0.1 to 10% by weight.

Claim 31

29 . The ink set according to claim 27 , wherein the normal yellow ink composition comprises, as a colorant, at least one member selected from the group consisting of C.I. Pigment Yellow 74, C.I. Pigment Yellow 93, C.I. Pigment Yellow 109, C.I. Pigment Yellow 110, C.I. Pigment Yellow 128, C.I. Pigment Yellow 138, C.I. Pigment Yellow 150, C.I. Pigment Yellow 151, C.I. Pigment Yellow 154, C.I. Pigment Yellow 155, C.I. Pigment Yellow 180, and C.I. Pigment Yellow 185.

Claim 32

30 . The ink set according to claim 1 , wherein the dark yellow ink composition contains at least a colorant, a water-soluble organic solvent, and water.

Claim 33

31 . The ink set according to claim 30 , wherein the colorant is a dye or a pigment.

Claim 34

32 . The ink set according to claim 30 , wherein the dark yellow ink composition contains at least a yellow colorant as the colorant.

Claim 35

33 . The ink set according to claim 30 , wherein the dark yellow ink composition contains a lower alkyl ether of a polyhydric alcohol as the water-soluble organic solvent.

Claim 36

34 . The ink set according to claim 30 , wherein the dark yellow ink composition further contains a surfactant.

Claim 37

35 . The ink set according to claim 34 , wherein the surfactant is an acetylene glycol surfactant.

Claim 38

36 . The ink set according to claim 1 , which further contains a magenta ink composition and a cyan ink composition.

Claim 39

37 . The ink set according to claim 27 , which further contains a magenta ink composition and a cyan ink composition, said magenta ink composition containing, as a colorant, at least one member selected from the group consisting of C.I. Pigment Red 122, C.I. Pigment Red 202, C.I. Pigment Red 209, and C.I. Pigment Violet 19, said cyan ink composition containing, as a colorant, at least one member selected from the group consisting of C.I. Pigment Blue 15:3, C.I. Pigment Blue 15:4, and C.I. Pigment Blue 60.

Claim 40

38 . The ink set according to claim 1 , which further contains two magenta ink compositions different from each other in color density and two cyan ink compositions different from each other in color density.

Claim 41

39 . The ink set according to claim 27 , which further contains two magenta ink compositions different from each other in color density and two cyan ink compositions different from each other in color density, the two magenta ink compositions, different from each other in color density, each independently containing, as a colorant, at least one member selected from the group consisting of C.I. Pigment Red 122, C.I. Pigment Red 202, C.I. Pigment Red 209, and C.I. Pigment Violet 19, the two cyan ink compositions, different from each other in color density, each independently containing, as a colorant, at least one member selected from the group consisting of C.I. Pigment Blue 15:3, C.I. Pigment Blue 15:4, and C.I. Pigment Blue 60.

Claim 42

40 . The ink set according to claim 36 , which further contains a black ink composition.

Claim 43

41 . The ink set according to claim 37 , which further contains a black ink composition, said black ink composition containing at least carbon black as a colorant.

Claim 44

42 . The ink set according to claim 1 , which is used in an ink jet recording method.

Claim 45

43 . A recording method comprising the step of depositing an ink composition onto a recording medium to perform printing, wherein the ink set according to claim 1 is used.

Claim 46

44 . An ink jet recording method comprising the steps of: ejecting droplets of an ink composition; and depositing the droplets onto a recording medium to perform printing, wherein the ink set according to claim 1 is used.

Claim 47

45 . A record produced by the recording method according to claim 43 .

Claim 48

46 . An ink cartridge comprising at least an ink reservoir for storing the dark yellow ink composition contained in the ink set according to claim 1 .

Claim 49

47 . An ink cartridge comprising partitioned ink reservoirs which are independent of each other and respectively contain the ink compositions constituting the ink set according to claim 1 .

Claim 50

48 . An ink cartridge set comprising a combination of a plurality of independent ink cartridges including: a dark yellow ink cartridge containing the dark yellow ink composition included in the ink set according to claim 1; and a normal yellow ink cartridge containing the normal yellow ink composition included in the ink set.

Claim 51

49 . The ink cartridge set according to claim 48 , which further comprises: a magenta ink cartridge containing a magenta ink composition; and a cyan ink cartridge containing a cyan ink composition.

Claim 52

50 . The ink cartridge set according to claim 48 , which further comprises: a light magenta ink cartridge containing a magenta ink composition having lower color density out of two magenta ink compositions different from each other in color density; a magenta ink cartridge containing a magenta ink composition having higher color density out of the two magenta ink compositions different from each other in color density; a light cyan ink cartridge containing a cyan ink composition having lower color density out of two cyan ink compositions different from each other in color density; and a cyan ink cartridge containing a cyan ink composition having higher color density out of the two cyan ink compositions different from each other in color density.

Claim 53

51 . The ink cartridge set according to claim 48 , which further comprises a black ink cartridge containing a black ink composition.

Claim 54

52 . The ink cartridge set according to claim 48 , wherein at least two ink cartridges included in the cartridge set are attached to each other by physical means.

Claim 55

53 . An ink jet recording apparatus for ejecting droplets of an ink composition and depositing the droplets onto a recording medium to perform printing, said ink jet recording apparatus comprising: the ink cartridge according to claim 46; a recording head for ejecting an ink composition contained in the ink cartridge; and means for supplying the ink composition from the ink cartridge to the recording head.

Claim 56

54 . An ink jet recording apparatus for ejecting droplets of an ink composition and depositing the droplets onto a recording medium to perform printing, said ink jet recording apparatus comprising: the ink cartridge set according to claim 48; a recording head for ejecting ink compositions contained in the ink cartridges constituting the ink cartridge set; and means for supplying the ink compositions from the ink cartridges to the recording head.

Claim 57

55 . A dark yellow ink composition for use in a recording method at least using two yellow ink compositions of a normal yellow ink composition and a dark yellow ink composition, said dark yellow ink composition being used in the ink set according to claim 1 .

Claim 58

56 . A dark yellow ink composition for use in a recording method at least using two yellow ink compositions of a normal yellow ink composition and a dark yellow ink composition, said dark yellow ink composition comprising C.I. Direct Black 195, C.I. Direct Yellow 86, and C.I. Direct Yellow 173 as colorants.

Claim 59

56 . A dark yellow ink composition for use in a recording method at least using two yellow ink compositions of a normal yellow ink composition and a dark yellow ink composition, said dark yellow ink composition comprising C.I. Direct Black 195, C.I. Direct Yellow 86, and C.I. Direct Yellow 173 as colorants.

Claim 60

57 . The dark yellow ink composition according to claim 56 , which further comprises, as a colorant, a magenta dye represented by formula M-4: M-4

Claim 61

58 . The dark yellow ink composition according to claim 57 , which further comprises C.I. Direct Blue 199 as a colorant.

Claim 62

59 . A dark yellow ink composition comprising, as colorants, at least one first colorant selected from the group consisting of compounds represented by formula (I) and (II) wherein R 1 , R 1 ′, R 2 , and R 2 ′ each independently represent CH 3 or OCH 3 ; and A and A′ each independently represent a group having a structure selected from the group consisting of wherein M represents hydrogen, lithium, sodium, potassium, ammonium, or an organic amine; and n is an integer of 1 or 2, and at least one second colorant selected from the group consisting of magenta, cyan, and black dyes.

Claim 63

59 . A dark yellow ink composition comprising, as colorants, at least one first colorant selected from the group consisting of compounds represented by formula (I) and (II) wherein R 1 , R 1 ′, R 2 , and R 2 ′ each independently represent CH 3 or OCH 3 ; and A and A′ each independently represent a group having a structure selected from the group consisting of wherein M represents hydrogen, lithium, sodium, potassium, ammonium, or an organic amine; and n is an integer of 1 or 2, and at least one second colorant selected from the group consisting of magenta, cyan, and black dyes.

Claim 64

60 . The dark yellow ink composition according to claim 59 , wherein the first colorant is selected from the group consisting of C.I. Direct Yellow 50, C.I. Direct Yellow 55, C.I. Direct Yellow 86, C.I. Direct Yellow 132, and C.I. Direct Yellow 173.

Claim 65

61 . The dark yellow ink composition according to claim 59 or 60 , wherein the second colorant is selected from the group consisting of: magenta dyes selected from compounds represented by formula (III) wherein M represents hydrogen, lithium, sodium, potassium, ammonium, or an organic amine, and R 3 represents chlorine or a group represented by formula wherein X represents an anilino group substituted by at least one SO 3 M, and Y represents OH, chlorine, or a morpholino group, R 4 represents hydrogen, chlorine, SO 3 M, or a C 1 -C 4 alkyl group, or compounds represented by formula (IV) wherein α represents a C 1 -C 4 alkyl or alkoxy group or an OH—, SO 3 H—, or COOM-substituted phenyl or naphthyl group, β represents hydrogen or a group represented by formula wherein R 5 represents hydrogen or an OH— or COOH-substituted C 1 -C 4 alkyl group, R 6 represents an OH—, OCH 3 —, OC 2 H 5 —, SO 3 M—, or COOM-substituted C 1 -C 4 alkyl or phenyl group, R 7 represents OH, COOH, or NHR 8 , and R 8 represents an SO 3 M— or COOH-substituted C 1 -C 4 alkyl group, M represents hydrogen, lithium, sodium, potassium, ammonium, or an organic amine; cyan dyes selected from compounds represented by formula (V) wherein R 9 represents OH, COOM, or R 10 COOM wherein R 10 represents C 4 -C 9 alkyl group, and l, m, and n are each 0 to 4, provided that (l+m+n)=4; and black dyes selected from C.I. Direct Black 195, C.I. Food Black 2, C.I. Sulfur Black 1, or C.I. Reactive Black 31 or C.I. Reactive Black 35.

Claim 66

62 . The dark yellow ink composition according to claim 59 , wherein the dark yellow ink composition has a lightness of 20 to 90, and the lightness of the ink composition is the lightness of an L*a*b* color system as calculated from the spectral characteristics of a 1000-fold dilution of the ink composition with water.

Claim 67

63 . The dark yellow ink composition according to claim 62 , wherein the dark yellow ink composition has a lightness of 30 to 80.