Ink set and image forming method

Patent metadata

Field	Value
Publication number	US-12084587-B2
Application number	US-202218049822-A
Country	US
Kind code	B2
Filing date	Oct 26, 2022
Priority date	Oct 29, 2021
Publication date	Sep 10, 2024
Grant date	Sep 10, 2024

Abstract

An ink set includes four types of inks that are a yellow ink, a magenta ink, a cyan ink, and a black ink. Each of the four types of inks contains water and a colorant, and at least one of the four types of inks contains an ultraviolet absorber. When Abs (Y) represents the absorbance of the yellow ink, Abs (M) represents the absorbance of the magenta ink, Abs (C) represents the absorbance of the cyan ink, and Abs (K) represents the absorbance of the black ink with respect to light with a wavelength of 385 nm, the ratios of Abs (Y), Abs (M), and Abs (C) to Abs (K) satisfy predetermined conditions.

First claim

What is claimed is:

1. An ink set comprising:
four types of inks that are a yellow ink, a magenta ink, a cyan ink, and a black ink, wherein
each of the four types of inks contains water and a colorant,
at least one ink of the four types of inks contains an ultraviolet absorber, and
the four types of inks with R (Y, K), R (M, K), and R (C, K) satisfy condition (a) in which R (Y, K), R (M, K), and R (C, K) are all 0.2 or more and 1.0 or less and condition (b) in which a difference between maximum and minimum values of R (Y, K), R (M, K), and R (C, K) is 0.5 or less, wherein
R (Y, K), R (M, K), and R (C, K) are represented by Equations (1) to (3) below
R ( Y,K )=Abs( Y )/Abs( K )  Equation (1)

R ( M,K )=Abs( M )/Abs( K )  Equation (2) and

R ( C,K )=Abs( C )/Abs( K )  Equation (3), where

Abs (Y) represents absorbance of the yellow ink with respect to light having a wavelength of 385 nm, Abs (M) represents absorbance of the magenta ink with respect to the light, Abs (C) represents absorbance of the cyan ink with respect to the light, and Abs (K) represents absorbance of the black ink with respect to the light.

2. The ink set according to claim 1 , wherein:
the four types of inks satisfy condition (c) in which R (Y, K), R (M, K), and R (C, K) are all 0.5 or more and 0.8 or less.

3. The ink set according to claim 1 , wherein:
the four types of inks satisfy condition (d) in which the difference between the maximum and minimum values of R (Y, K), R (M, K), and R (C, K) is 0.3 or less.

4. The ink set according to claim 1 , wherein:
the yellow ink and the black ink satisfy condition (e) in which R (Y, K) is 0.5 or more and 1.0 or less.

5. The ink set according to claim 1 , wherein:
the magenta ink and the black ink satisfy condition (f) in which R (M, K) is 0.4 or more and 1.0 or less.

6. The ink set according to claim 1 , wherein:
the cyan ink and the black ink satisfy condition (g) in which R (C, K) is 0.4 or more and 1.0 or less.

7. The ink set according to claim 1 , wherein:
the at least one ink containing the ultraviolet absorber contains 0.1 mass % or more and 3.0 mass % or less of the ultraviolet absorber with respect to total mass of the at least one ink.

8. The ink set according to claim 1 , wherein:
the ultraviolet absorber contained in the at least one ink is contained in a resin particle.

9. The ink set according to claim 8 , wherein:
the resin particle containing the ultraviolet absorber is at least one type of resin particle selected from the group consisting of acrylic resin particles, styrene resin particles, urethane resin particles, urethane-acrylic resin particles, and styrene-acrylic resin particles.

10. The ink set according to claim 1 , wherein:
the four types of inks are all inkjet inks.

11. An image forming method using four types of inks that are a yellow ink, a magenta ink, a cyan ink, and a black ink, the method comprising:
applying one of the yellow ink, the magenta ink, and the cyan ink onto a surface of a recording medium; and
applying another one of the yellow ink, the magenta ink, and the cyan ink onto the surface of the recording medium,
wherein
each of the four types of inks contains water and a colorant,
at least one ink of the four types of inks contains an ultraviolet absorber, and
the four types of inks with R (Y, K), R (M, K), and R (C, K) satisfy condition (a) in which R (Y, K), R (M, K), and R (C, K) are all 0.2 or more and 1.0 or less and condition (b) in which a difference between maximum and minimum values of R (Y, K), R (M, K), and R (C, K) is 0.5 or less, wherein
R (Y, K), R (M, K), and R (C, K) are represented by Equations (1) to (3) below
R ( Y,K )=Abs( Y )/Abs( K )  Equation (1)

R ( M,K )=Abs( M )/Abs( K )  Equation (2) and

R ( C,K )=Abs( C )/Abs( K )  Equation (3), where

Abs (Y) represents absorbance of the yellow ink with respect to light having a wavelength of 385 nm, Abs (M) represents absorbance of the magenta ink with respect to the light, Abs (C) represents absorbance of the cyan ink with respect to the light, and Abs (K) represents absorbance of the black ink with respect to the light.

12. The image forming method according to claim 11 , wherein:
the inks applied onto the surface of the recording medium are applied by an inkjet method.

Assignees

• Konica Minolta Inc

Inventors

• Goto Masaki

Classifications

• C09D11/322

  Pigment inks · CPC title

• C09D11/107

  from unsaturated acids or derivatives thereof · CPC title

• C09D11/106

  containing macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds · CPC title

• C09D11/102

  containing macromolecular compounds obtained by reactions other than those only involving unsaturated carbon-to-carbon bonds · CPC title

• C09D11/326

  characterised by the pigment dispersant · CPC title