JP2018048282A - Aqueous ink for ink jet recording, aqueous ink set for ink jet recording, ink jet recording method, and ink jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous ink for ink jet recording which realizes both storage stability of an ink containing a specific compound and suppression of deterioration of image quality at the time of ink jet recording, compared with a case where the ink pH is out of the range from 6.5 to 8.5.SOLUTION: An aqueous ink for ink jet recording includes: water; a water-soluble organic solvent; a coloring material; and a squarylium compound represented by formula (I), where the ink pH is in a range from 6.5 to 8.5.SELECTED DRAWING: None

Description

  The present invention relates to an aqueous inkjet recording ink, an aqueous inkjet recording ink set, an inkjet recording method, and an inkjet recording apparatus.

  In a water-based inkjet recording apparatus for mass printing, high-speed printing is required as compared with a water-based inkjet recording apparatus for home and office use. From the viewpoint of image fixing, a solvent contained in ink using a drying apparatus after printing. Is evaporating.

  In such an aqueous inkjet recording apparatus, a method has been proposed in which a near-infrared absorbent having a near-infrared absorbing ability is added to ink and dried and fixed by irradiation with near-infrared rays after printing. By irradiating near-infrared rays to the ink printed on the recording medium and rapidly evaporating the solvent in the ink, the penetration and diffusion of the solvent into the recording medium are suppressed, and the image quality is improved.

  For example, Patent Document 1 describes an inkjet recording liquid containing a dye such as a squarylium dye having a transmission density at 420 nm of less than 0.03 when the transmission density at a maximum absorption wavelength is 1.0 in a solvent. ing.

  Patent Document 2 includes a near-infrared absorber selected from at least a coloring material, water, a water-soluble organic solvent, and a phthalocyanine compound, an onium compound, a cyanine compound, and a nickel complex having a maximum absorption wavelength of 800 nm to 1200 nm. In addition, there is described an aqueous inkjet recording ink in which the near-infrared absorbent is adsorbed or encapsulated in resin fine particles and dispersed in the form of near-infrared absorbent-containing resin fine particles.

JP 2002-080764 A JP 2013-189596 A

  The object of the present invention is to achieve both the storage stability of an ink containing a specific compound and the suppression of deterioration in image quality during ink jet recording, as compared with the case where the ink pH is outside the range of 6.5 or more and 8.5 or less. Another object of the present invention is to provide an aqueous ink jet recording ink, an aqueous ink jet recording ink set, an ink jet recording method using the ink and the ink set, and an ink jet recording apparatus.

（一般式（Ｉ）において、Ｒ^ａ，Ｒ^ｂ，Ｒ^ｃ，Ｒ^ｄは、それぞれ独立して、一般式（I−Ｒ）で示される構造あるいは分岐していない炭素数１以上６以下のアルキル基を表す。Ｒ^１は、水素原子またはメチル基、ｎは０以上３以下の整数を表す。一般式（I−Ｒ）で示される構造の総炭素数は６以下である。） The invention according to claim 1 includes water, a water-soluble organic solvent, a coloring material, and a specific compound having a structure represented by the following general formula (I), and has an ink pH of 6.5 or more and 8.5 or less. This is an ink for water-based inkjet recording.

(In the general formula (I), R ^a , R ^b , R ^c and R ^d each independently represents a structure represented by the general formula (IR) or an unbranched alkyl having 1 to 6 carbon atoms. R ¹ represents a hydrogen atom or a methyl group, n represents an integer of 0 or more and 3 or less, and the total carbon number of the structure represented by the general formula (IR) is 6 or less.

  The invention according to claim 2 is the water-based inkjet recording ink according to claim 1, further comprising a resin dispersant, wherein the specific compound is dispersed in the ink by the resin dispersant.

（一般式（ＩＩ）において、Ｒ^２は、水素原子、メチル基、あるいは−Ｘ−Ｒ^３−Ａ^１を示し、Ｒ^４は、水素原子、あるいは−Ｘ−Ｒ^３−Ａ^１を示し、Ｘは、−Ｃ（＝Ｏ）−，−Ｃ（＝Ｏ）Ｏ−，−Ｃ（＝Ｏ）ＮＨ−，−ＯＣ（＝Ｏ）−，フェニレン、複素環の２価基、あるいは単結合を示し、Ｒ^３は、２価の連結基、あるいは単結合を示し、Ａ_１は、−ＳＯ_３Ｈ、−ＣＯＯＨまたは−ＯＰＯ_３Ｈ_２を示す。一般式（IＩ）で示される繰り返し単位において、同一単位で−Ｘ−Ｒ^３−Ａ^１が２個以上存在する場合は、Ｘ、Ｒ^３またはＡ^１はそれぞれ互いに同じでも異なっていてもよい。また、異なる構造の単位が同一分子内に複数存在してもよい。） In the invention according to claim 3, the resin dispersant includes a structural unit represented by the following general formula (II) and a structural unit derived from alkyl (meth) acrylate, and has an acid value of 6 mgKOH / g or more and 100 mgKOH / The water-based inkjet recording ink according to claim 2, which is a vinyl polymer having a g or less.

(In General Formula (II), R ² represents a hydrogen atom, a methyl group, or —X—R ³ —A ¹ , R ⁴ represents a hydrogen atom, or —X—R ³ —A ¹ , Represents —C (═O) —, —C (═O) O—, —C (═O) NH—, —OC (═O) —, phenylene, a heterocyclic divalent group, or a single bond. , R ³ represents a divalent linking group or a single bond, and A ₁ represents —SO ₃ H, —COOH or —OPO ₃ H _{2. In the} repeating unit represented by formula (II), the same When two or more -X-R ³ -A ¹ are present as a unit, X, R ³ or A ¹ may be the same or different from each other, and a plurality of units having different structures are present in the same molecule. You may do it.)

  The invention according to claim 4 is the water-based ink jet recording ink according to claim 2, wherein the resin dispersant is polyester.

  The invention according to claim 5 is water, a water-soluble organic solvent, a black ink containing carbon black as a coloring material, and the water-based inkjet recording ink according to any one of claims 1 to 4, An ink set for water-based inkjet recording, wherein the color material is composed of one or more color inks that are chromatic color materials.

  According to a sixth aspect of the present invention, the water-based inkjet recording ink according to any one of the first to fourth aspects or the water-based inkjet recording ink set according to the fifth aspect is applied from a recording head to a recording medium. After that, an ink jet recording method is performed in which a near-infrared laser having a center wavelength in the range of 750 nm or more and 950 nm or less is irradiated to perform ink drying and recording.

  The invention according to claim 7 performs recording by repeatedly irradiating a near-infrared laser having a center wavelength in the range of 750 nm or more and 950 nm or less after applying ink to the recording medium for each color ink. 6. The inkjet recording method according to 6.

  According to the eighth aspect of the invention, after applying ink to the recording medium for each color ink, irradiation with a near-infrared laser having a center wavelength in the range of 750 nm or more and 950 nm or less is repeated, and the ink to be recorded last. The ink jet recording method according to claim 6, wherein after the ink is applied to the recording medium, the ink is dried by heating the recording medium without irradiating the near infrared laser.

  The invention according to claim 9 is the ink jet recording method according to claim 6, wherein after applying ink of all colors to the recording medium, a near-infrared laser having a center wavelength in the range of 750 nm to 950 nm is irradiated. .

  The invention according to claim 10 applies the ink to the recording medium by discharging the water-based inkjet recording ink according to any one of claims 1 to 4 or the water-based inkjet recording ink set according to claim 5. An inkjet recording apparatus comprising: a recording head; and a near-infrared laser emitting device that irradiates a near-infrared laser having a center wavelength in a range of 750 nm to 950 nm with respect to ink applied to the recording medium. .

  According to the first aspect of the present invention, compared to the case where the ink pH is outside the range of 6.5 or more and 8.5 or less, the storage stability of the ink containing the specific compound and the suppression of the deterioration of the image quality when the ink jet recording is performed. A water-based inkjet recording ink that satisfies both requirements is provided.

  According to the second aspect of the present invention, there is provided an aqueous inkjet recording ink having better storage stability than when the specific compound is not dispersed in the ink by the resin dispersant.

  According to the invention of claim 3, there is provided an aqueous inkjet recording ink having better storage stability than when the resin dispersant is not a resin having a repeating unit represented by the above general formula (II). The

  According to the invention which concerns on Claim 4, compared with the case where a resin dispersing agent is not polyester, the water-based inkjet recording ink which is favorable in storage stability is provided.

  According to the invention of claim 5, compared to the case where the ink pH is outside the range of 6.5 or more and 8.5 or less, the storage stability of the ink containing the specific compound and the suppression of the deterioration of the image quality when the ink jet recording is performed. An ink set for water-based inkjet recording that satisfies both requirements is provided.

  According to the invention of claim 6, compared to the case where the ink pH is outside the range of 6.5 or more and 8.5 or less, the storage stability of the ink containing the specific compound and the suppression of the deterioration of the image quality when the ink jet recording is performed. An ink jet recording method is provided.

  According to the seventh aspect of the present invention, there is provided an ink jet recording method capable of obtaining a good image quality as compared with a case where no near infrared laser is irradiated.

  According to the eighth aspect of the present invention, there is provided an ink jet recording method capable of obtaining a better image quality as compared with the case of irradiating a near infrared laser after the last recording ink is applied to a recording medium.

  According to the ninth aspect of the present invention, there is provided an ink jet recording method capable of obtaining a good image quality as compared with a case where no near-infrared laser is irradiated.

  According to the invention of claim 10, as compared with the case where the ink pH is outside the range of 6.5 or more and 8.5 or less, the storage stability of the ink containing the specific compound and the suppression of the image quality deterioration during ink jet recording are reduced. An ink jet recording apparatus that satisfies both of the above is provided.

1 is a schematic configuration diagram illustrating an example of an inkjet recording apparatus according to an embodiment of the present invention. It is a schematic block diagram which shows the other example of the inkjet recording device which concerns on embodiment of this invention. It is a schematic block diagram which shows the other example of the inkjet recording device which concerns on embodiment of this invention.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

  In a water-based inkjet recording, when a permeable recording medium is used, fixability can be ensured. However, penetration and diffusion into the recording medium occur before the solvent in the ink evaporates, thereby causing image defects such as image bleeding. May occur or the image density may not be sufficient. On the other hand, when a low-penetration recording medium such as coated paper for printing is used, before the solvent in the ink evaporates, image defects such as unevenness and white streaks occur due to droplet ejection interference on the recording medium. It was easy to occur.

  As an ink drying method in water-based inkjet recording, the present inventors have mounted a near-infrared laser, rapidly irradiating near-infrared rays to ink containing a specific specific compound printed on a recording medium. In addition, by evaporating a solvent such as moisture in the ink to suppress the deterioration of the image quality and adjusting the ink pH to a specific range, it has been found that there is no problem in the storage stability of the ink. Thereby, both the storage stability of the ink containing the specific compound and the suppression of the deterioration of the image quality at the time of ink jet recording are compatible. In addition, even when a low-penetration recording medium is used, the occurrence of image defects during recording is suppressed, and the storage stability of the ink is compatible.

  After the ink is printed on the recording medium, the ink is rapidly evaporated by irradiating a near-infrared laser. When a permeable recording medium is used, the fixing property is secured and the solvent in the ink is evaporated. The occurrence of image defects such as image blurring and the decrease in image density due to the penetration and diffusion of the recording medium before the recording are suppressed. When using a low-penetration recording medium such as coated paper for printing, unevenness due to ink droplet ejection interference occurring on the recording medium before the solvent in the ink evaporates, white streaks, etc. The occurrence of image defects is suppressed. Further, when the ink pH is in the range of 6.5 or more and 8.5 or less, deterioration of the specific compound over time, deterioration of pigment dispersion stability, and the like are suppressed.

<Water-based inkjet recording ink>
The water-based inkjet recording ink according to this embodiment includes water, a water-soluble organic solvent, a coloring material, and a specific compound having a structure represented by the following general formula (I), and has an ink pH of 6.5 or more. The ink is in the range of 8.5 or less. Hereinafter, each component contained in the water-based inkjet recording ink according to the present embodiment will be described.

（一般式（Ｉ）において、Ｒ^ａ，Ｒ^ｂ，Ｒ^ｃ，Ｒ^ｄは、それぞれ独立して、一般式（I−Ｒ）で示される構造あるいは分岐していない炭素数１以上６以下のアルキル基を表す。Ｒ^１は、水素原子（Ｈ）またはメチル基、ｎは０以上３以下の整数を表す。一般式（I−Ｒ）で示される構造の総炭素数は６以下である。一般式（Ｉ）において、Ｒ^ａ，Ｒ^ｂ，Ｒ^ｃ，Ｒ^ｄは、それぞれ独立して、一般式（I−Ｒ）で示される構造であることが好ましく、Ｒ^１は、メチル基であることが好ましく、ｎは０または１であることが好ましい。） (Specific compounds)
The aqueous inkjet recording ink according to the present embodiment contains a specific compound. In the water-based inkjet recording ink according to this embodiment, the specific compound having a specific structure is a squarylium compound having a structure represented by the following general formula (I).

(In the general formula (I), R ^a , R ^b , R ^c and R ^d each independently represents a structure represented by the general formula (IR) or an unbranched alkyl having 1 to 6 carbon atoms. R ¹ represents a hydrogen atom (H) or a methyl group, n represents an integer of 0 or more and 3 or less, and the total carbon number of the structure represented by the general formula (I-R) is 6 or less. In the formula (I), R ^a , R ^b , R ^c , and R ^d are each independently preferably a structure represented by the general formula (IR), and R ¹ is a methyl group And n is preferably 0 or 1.)

  The specific compound has excellent absorbency of near-infrared light having a center wavelength in the range of 750 nm to 950 nm, particularly near infrared light of 800 nm to 850 nm, and is difficult to decompose over time, and has excellent dispersion stability in water. ing. As the specific compound, a compound that does not easily change the hue required for the ink is selected.

  The ink pH is in the range of 6.5 to 8.5, and preferably in the range of 6.7 to 8.2. The specific compound has excellent properties that are difficult to decompose over time. However, when the specific compound is dispersed in water, the pH of the specific compound dispersion and the ink to which the specific compound is added exceeds 8.5. As the decomposition proceeds, the near-infrared absorption efficiency is reduced, and thus the ink evaporation rate is slowed down. When a permeable recording medium is used, the penetration and diffusion of the ink into the recording medium occurs. When a permeable recording medium is used, droplet ejection interference occurs between ink droplets. Also, high speed printing becomes difficult.

  In addition, when the pH of the ink is less than 6.5, the absorption spectrum of the color material changes to exhibit a color tone different from the original color, and the dispersion stability of the color material and the specific compound in water also deteriorates. Aggregates are formed over time, and sedimentation occurs. Such a phenomenon is not observed when the specific compound is not included, and is presumed to be due to the influence of the interaction between the color material and the specific compound.

Examples of the specific compound include specific compounds represented by the following structural formulas (A) and (B). Here, the specific compound represented by the following structural formula (A) is represented by the general formula (I), wherein R ^a , R ^b , R ^c , and R ^d are represented by the general formula (IR), and R ¹ is methyl. The group, n is 0. The specific compound represented by the following structural formula (B) is represented by the general formula (I), wherein R ^a , R ^b , R ^c and R ^d are represented by the general formula (IR), R ¹ is a methyl group, n Is a structure of 1.

  The content of the specific compound in the water-based inkjet recording ink according to the present embodiment may be determined according to a desired near infrared absorption amount, an ink discharge amount by the apparatus, and the like. The content of the specific compound is, for example, in the range of 0.001% by mass to 0.5% by mass and in the range of 0.005% by mass to 0.3% by mass with respect to the entire ink. More preferred. If the content of the specific compound in the water-based inkjet recording ink is less than 0.001% by mass, the near-infrared absorption may be insufficient, and if it exceeds 0.5% by mass, the color tone of the ink may be affected. In some cases, a near-infrared absorber is deposited.

(Resin dispersant)
The aqueous inkjet recording ink according to this embodiment preferably further includes a resin dispersant, and the specific compound is preferably dispersed in the ink by the resin dispersant. Since the specific compound has low solubility or insolubility in water, it is preferable that fine particles are dispersed in water using a resin dispersant.

  Here, “dispersed” and “dispersed in fine particles” mean that the volume average particle size of the dispersion containing the specific compound in the ink is in the range of, for example, 5 nm to 150 nm, preferably 10 nm to 80 nm. It is distributed in the range state. If the volume average particle size of the ink is measured using a laser diffraction particle size distribution measuring device, the particle size distribution peak of the colorant (pigment) and the particle size distribution peak of the specific compound dispersion are usually separated. It can be determined that the specific compound is dispersed with the volume average particle diameter by the resin dispersant in the ink.

  Examples of the resin dispersant include conventionally known ones, which may be any of a water-insoluble resin, a water-dispersed (self-emulsifying) resin, and a water-soluble resin. Water-insoluble resins and water-dispersed (self-emulsifying) resins are preferable in view of properties, and water-dispersed (self-emulsifying) resins are particularly preferable in terms of dispersion stability and the like. If the resin dispersant is a water-soluble resin, the specific compound may be difficult to disperse and emulsify in the ink.

（一般式（ＩＩ）において、Ｒ^２は、水素原子（Ｈ）、メチル基、あるいは−Ｘ−Ｒ^３−Ａ^１を示し、Ｒ^４は、水素原子、あるいは−Ｘ−Ｒ^３−Ａ^１を示し、Ｘは、−Ｃ（＝Ｏ）−，−Ｃ（＝Ｏ）Ｏ−，−Ｃ（＝Ｏ）ＮＨ−，−ＯＣ（＝Ｏ）−，フェニレン、複素環の２価基、あるいは単結合を示し、Ｒ^３は、２価の連結基、あるいは単結合を示し、Ａ_１は、−ＳＯ_３Ｈ、−ＣＯＯＨまたは−ＯＰＯ_３Ｈ_２を示す。一般式（IＩ）で示される繰り返し単位において、同一単位で−Ｘ−Ｒ^３−Ａ^１が２個以上存在する場合は、Ｘ、Ｒ^３またはＡ^１はそれぞれ互いに同じでも異なっていてもよい。また、異なる構造の単位が同一分子内に複数存在してもよい。）
（ｇ）親水性の構成単位として少なくとも１種がカルボキシ基を有する構成単位と、アルキル（メタ）アクリレートに由来する構成単位とを含み、酸価が１５ｍｇＫＯＨ／ｇ以上１５０ｍｇＫＯＨ／ｇ以下であるポリマー The resin dispersant for the water-dispersed (self-emulsifying) resin is preferably at least one selected from the following (a) to (g).
(A) Polyurethane (b) Polyester (c) Polyamide (d) Polyurea (e) Polycarbonate (f) Structural unit (repeating unit) represented by the following general formula (II) and a structural unit derived from alkyl (meth) acrylate A vinyl polymer having an acid value of 6 mgKOH / g or more and 100 mgKOH / g or less

(In General Formula (II), R ² represents a hydrogen atom (H), a methyl group, or —X—R ³ —A ¹ , and R ⁴ represents a hydrogen atom, or —X—R ³ —A ¹ . X represents —C (═O) —, —C (═O) O—, —C (═O) NH—, —OC (═O) —, phenylene, a heterocyclic divalent group, or a single group. R ³ represents a divalent linking group or a single bond, and A ₁ represents —SO ₃ H, —COOH or —OPO ₃ H _{2. The} repeating unit represented by the general formula (II) In the case where two or more —X—R ³ —A ¹ are present in the same unit, X, R ³ or A ¹ may be the same or different from each other. There may be more than one.)
(G) A polymer having a structural unit having at least one carboxy group as a hydrophilic structural unit and a structural unit derived from an alkyl (meth) acrylate and having an acid value of 15 mgKOH / g or more and 150 mgKOH / g or less

(F) Examples of the structural unit represented by the general formula (II) in the vinyl polymer include acrylic acid (R ² = R ⁴ = H, X = R ³ = single bond, A ¹ = -COOH), methacrylic acid (R ² = —CH ₃ , R ⁴ = H, X = R ³ = single bond, A ¹ = —COOH), 2-carboxyethyl acrylate (β-carboxyethyl acrylate) (R ² = R ⁴ = H , X = —C (═O) O—, R ³ = —CH ₂ CH ₂ —, A ¹ = —COOH), styrene carboxylic acid (R ² = R ⁴ = H, X = phenylene, R ³ = single bond , ^A 1 = -COOH), 2- acrylamido-2-methylpropanesulfonic acid ^{(= R 2 = R 4 H} , X = -C (= O) NH-, R 3 = -C (-CH 3) 2 - _{^{CH 2 -, A 1 = -SO}} 3 H), styrene sulfonic Sanna Potassium ^{(R 2 = R 4 = H} , X = phenylene, ^{R 3} = single ^bond, A 1 = _-SO 3 H (or _-SO 3 Na)), phosphoric acid mono 2- (meth) acryloyl ethyl ^(R 2 = _{^{CH 3, R 4 = H,}} X = -C (= O) O-, R 3 = -CH 2 CH 2 -, A 1 = -OPO 3 H 2), itaconic acid ^(R 2 = -COOH [X = R ³ = single ^{bond, A 1 = -COOH], R} 4 = H, X = single _{^{bond, R 3 = -CH 2 -,}} A 1 = -COOH), maleic acid ^{(R 2 = H, R 4} = - COOH [X = R ³ = single bond, A ¹ = -COOH], X = R ³ = single bond, A ¹ = -COOH) and the like. In the structural unit represented by the general formula (II), the number of —X—R ³ —A ¹ is preferably one.

  (F) As a structural unit derived from alkyl (meth) acrylate in a vinyl polymer (“alkyl (meth) acrylate” means “alkyl acrylate” or “alkyl methacrylate”), for example, methyl (meta ) Acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, methoxyethyl (meth) acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, methoxytriethylene glycol (meth) acrylate, And ethoxytriethylene glycol (meth) acrylate.

  (F) As a bivalent coupling group in a vinyl polymer, C1-C5 alkylene groups, such as a methylene group, ethylene group, a propylene group, a 1, 1- dimethylethylene group, etc. are mentioned, for example.

  (F) Examples of the divalent group of the heterocyclic ring in the vinyl polymer include a divalent group of pyridine and a divalent group of morpholine.

  (F) The acid value of the vinyl polymer is in the range of 6 mgKOH / g to 100 mgKOH / g, preferably in the range of 10 mgKOH / g to 100 mgKOH / g, and more preferably in the range of 10 mgKOH / g to 90 mgKOH / g.

  (G) Examples of the structural unit having at least one carboxy group as the hydrophilic structural unit in the polymer include acrylic acid and methacrylic acid.

  (G) The acid value of the polymer is in the range of 15 mgKOH / g to 150 mgKOH / g, preferably in the range of 20 mgKOH / g to 130 mgKOH / g, and more preferably in the range of 30 mgKOH / g to 100 mgKOH / g.

  From the viewpoint of compatibility with a specific compound, dispersion stability, and the like, the resin dispersant is more preferably (a) polyurethane, (b) polyester, and the vinyl polymer of (f) above, and the vinyl polymer of (f) above. And (b) polyester is more preferred. A resin dispersing agent may be used individually by 1 type, and may use 2 or more types together.

  The acid value of (a) polyurethane and (b) polyester is preferably in the range of 5 mgKOH or more and 150 mgKOH / g or less, from the viewpoint of the emulsifying property of the resin, the dispersibility of the specific compound, and the like. The range of g or less is more preferable.

  The weight average molecular weight of the resin dispersant is, for example, preferably in the range of 3000 to 200,000, more preferably in the range of 5000 to 150,000, and further in the range of 10,000 to 100,000. preferable. By setting the weight average molecular weight of the resin dispersant to 3000 or more, the amount of the water-soluble component is effectively suppressed, and by setting the weight average molecular weight to 200,000 or less, the dispersion stability of the specific compound can be improved.

  When the acid value of the resin dispersant is less than the above lower limit value, the specific compound is difficult to disperse in the ink, and when the upper limit value is exceeded, the resin dispersant becomes water-soluble, and the specific compound is dispersed and emulsified in the ink. It may be difficult to be done.

  Specific examples of (a) polyurethane, (b) polyester, (c) polyamide, (d) polyurea, and (e) polycarbonate, which are resin dispersants, are shown below.

PA-1: 4,4′-diphenylmethane diisocyanate / hexamethylene diisocyanate / tetraethylene glycol / ethylene glycol / 2,2-bis (hydroxymethyl) propionic acid (40/10/20/20/10 (molar ratio, hereinafter the same) ))
PA-2: 4,4′-diphenylmethane diisocyanate / hexamethylene diisocyanate / butanediol / ethylene glycol / 2,2-bis (hydroxymethyl) propionic acid (40/10/20/20/10)
PA-3: 1,5-naphthylene diisocyanate / butanediol / 2,2′-bis (4-hydroxyphenyl) propane / polypropylene glycol (Mw = 400) / 2,2-bis (hydroxymethyl) propionic acid (50 / 20/5/10/15)
PA-4: 1,5-naphthylene diisocyanate / hexamethylene diisocyanate / 2,2-bis (hydroxymethyl) butanoic acid / polybutylene oxide (Mw = 500) (35/15/25/25)
PA-5: Isophorone diisocyanate / diethylene glycol / neopentyl glycol / 2,2-bis (hydroxymethyl) propionic acid (50/20/20/10)
PA-6: Toluene diisocyanate / 2,2-bis (hydroxymethyl) butanoic acid / polyethylene glycol (Mw = 1000) / cyclohexanedimethanol (50/10/10/30)
PA-7: Toluene diisocyanate / ethylene glycol / 1,4-butanediol / 2,4-di (2-hydroxy) ethyloxycarbonylbenzenesulfonic acid (50/15/32/3)
PA-8: Isophorone diisocyanate / diethylene glycol / neopentyl glycol / 2,4-di (2-hydroxy) ethyloxycarbonylbenzenesulfonic acid (50/20/25/5)
PA-9: Diphenylmethane diisocyanate / hexamethylene diisocyanate / tetraethylene glycol / butanediol / 2,4-di (2-hydroxy) ethyloxycarbonylbenzenesulfonic acid (40/10/10
/ 33/7)
PA-10: Diphenylmethane diisocyanate / hexamethylene diisocyanate / butanediol / ethylene glycol / 2,2-bis (hydroxymethyl) butanoic acid / 2,4-di (2-hydroxy) ethyloxycarbonylbenzenesulfonic acid (40/10 / 20/15/10/5)
PA-11: terephthalic acid / isophthalic acid / cyclohexanedimethanol / 1,4-butanediol / ethylene glycol (25/25/25/15/10)
PA-12: terephthalic acid / isophthalic acid / 2,2′-bis (4-hydroxyphenyl) propane / tetraethylene glycol / ethylene glycol (30/20/20/15/15)
PA-13: terephthalic acid / isophthalic acid / cyclohexanedimethanol / neopentyl glycol / diethylene glycol (20/30/25/15/10)
PA-14: terephthalic acid / isophthalic acid / 4,4′-benzenedimethanol / diethylene glycol / neopentyl glycol (25/25/25/15/10)
PA-15: terephthalic acid / isophthalic acid / 5-sulfoisophthalic acid / ethylene glycol / neopentyl glycol (24/24/2/25/25)
PA-16: terephthalic acid / isophthalic acid / 5-sulfoisophthalic acid / cyclohexanedimethanol / 1,4-butanediol / ethylene glycol (22/22/6/25/15/10)
PA-17: Isophthalic acid / 5-sulfoisophthalic acid / cyclohexanedimethanol / ethylene glycol (40/10/40/10)
PA-18: cyclohexanedicarboxylic acid / isophthalic acid / 2,4-di (2-hydroxy) ethyloxycarbonylbenzenesulfonic acid / cyclohexanedimethanol / ethylene glycol (30/20/5/25/20)
PA-19: 12-aminododecanoic acid (100)
PA-20: Reaction product of poly (12-aminododecanoic acid) and maleic anhydride PA-21: 11-aminoundecanoic acid / 7-aminoheptanoic acid (50/50)
PA-22: tetramethylenediamine / adipic acid (50/50)
PA-23: Hexamethylenediamine / Sebacic acid (50/50)
PA-24: N, N-dimethylethylenediamine / adipic acid / cyclohexanedicarboxylic acid (50/20/30)
PA-25: Toluene diisocyanate / hexamethylenediamine / 2,2-bis (hydroxymethyl) propionic acid (50/40/10)
PA-26: isophorone diisocyanate / poly (oxytetramethylene) glycol: number average molecular weight 2,000 / neopentyl glycol / dimethylolpropionic acid (50 / 13.4 / 28.4 / 12.2)
PA-27: isophorone diisocyanate / polypropylene glycol: number average molecular weight 1,000 / neopentyl glycol / dimethylolpropionic acid (50/20/15/15)
PA-28: isophorone diisocyanate / poly (oxytetramethylene) glycol: number average molecular weight 2,000 / triethylene glycol / 2,4-di (2-hydroxy) ethyloxycarbonylbenzenesulfonic acid (50/20/18/12 )
PA-29: isophorone diisocyanate / poly (oxytetramethylene) glycol (Mn2000) / neopentylglycol / 2,2-bis (hydroxymethyl) propionic acid (50 / 9.5 / 6.2 / 34.3)

  Specific examples of the resin dispersant (f) vinyl polymer are shown below.

PV-01: Phenoxyethyl acrylate / methyl methacrylate / acrylic acid / acrylic acid-2-carboxyethyl copolymer (50/44/1/5)
PV-02: Phenoxyethyl acrylate / benzyl methacrylate / isobutyl methacrylate / styrene carboxylic acid copolymer (30/35/25/10)
PV-03: Phenoxyethyl methacrylate / isobutyl methacrylate / 2-acrylamido-2-methylpropanesulfonic acid copolymer (50/44/6)
PV-04: styrene / butyl acrylate / ethyl methacrylate / acrylic acid-2-carboxyethyl copolymer (30/15/49/6)
PV-05: styrene / butyl acrylate / ethyl methacrylate / sodium styrene sulfonate copolymer (30/20/44/6)
PV-06: Styrene / phenoxyethyl acrylate / methyl methacrylate / acrylic acid-2-carboxyethyl copolymer (10/50/35/5)
PV-07: benzyl acrylate / methyl methacrylate / acrylic acid-2-carboxyethyl copolymer (55/40/5)
PV-08: phenoxyethyl methacrylate / benzyl acrylate / styrene carboxylic acid copolymer (45/47/8)
PV-09: Styrene / phenoxyethyl acrylate / butyl methacrylate / acrylic acid-2-carboxyethyl copolymer (5/48/40/7)
PV-10: benzyl methacrylate / phenoxyethyl methacrylate / methyl methacrylate / mono- (meth) acryloylethyl phosphate copolymer (30/30/30/10)
PV-11: benzyl acrylate / methyl methacrylate / butyl acrylate / 2-acrylamido-2-methylpropane sulfonic acid copolymer (12/50/30/8)
PV-12: Styrene / ethyl methacrylate / acrylic acid-2-carboxyethyl copolymer (30/60/10)
PV-13: Styrene / phenoxyethyl methacrylate / butyl acrylate / acrylic acid-2-carboxyethyl copolymer (15/76/5/4)
PV-14: Methyl methacrylate / phenoxyethyl methacrylate / benzyl acrylate / acrylic acid-2-carboxyethyl copolymer (50/30/15/5)
PV-15: Methyl methacrylate / butyl methacrylate / 2-acrylamido-2-methylpropanesulfonic acid copolymer (56/40/4)
PV-16: benzyl acrylate / 2-carboxyethyl acrylate copolymer (90/10)
PV-17: Methyl methacrylate / methoxyethyl acrylate / benzyl methacrylate / itaconic acid copolymer (44/15/35/6)
PV-18: Ethyl methacrylate / styrene / maleic acid copolymer (46/50/4)
PV-19: Methyl methacrylate / benzyl methacrylate / methoxypolyethylene glycol methacrylate (n = 23) / 2-acrylamido-2-methylpropanesulfonic acid copolymer (74/15/5/6)
PV-20: benzyl methacrylate / ethoxytriethylene glycol methacrylate / mono 2- (meth) acryloylethyl phosphate copolymer (65/30/5)
PV-21: Methyl methacrylate / butyl acrylate / acrylic acid-2-carboxyethyl copolymer (75/19/6)
PV-22: Phenoxyethyl acrylate / benzyl methacrylate / isobutyl methacrylate / styrene sulfonic acid copolymer (30/35/29/6)
PV-23: benzyl methacrylate / ethyl methacrylate / β-carboxyethyl acrylate copolymer (60/25/15)
PV-24: Phenoxyethyl methacrylate / ethyl methacrylate / methacrylic acid copolymer (50/38/12)
PV-25: benzyl methacrylate / ethyl methacrylate / β-carboxyethyl acrylate copolymer (60/18/22)

  Specific examples of the polymer (g) which is a resin dispersant are shown below.

P-1: n-butyl acrylate / acrylic acid copolymer (80/20)
P-2: Methyl methacrylate / isobutyl methacrylate / acrylic acid copolymer (52/28/20)
P-3: sec-butyl acrylate / acrylic acid copolymer (85/15)
P-4: n-butyl methacrylate / pentyl methacrylate / methacrylic acid copolymer (38/38/24)
P-5: Isobutyl acrylate / glycidyl methacrylate / acrylic acid copolymer (75/15/10)
P-6: Isopropyl acrylate / acrylic acid copolymer (90/10)
P-7: Butyl methacrylate / 2-hydroxyethyl methacrylate / acrylic acid copolymer (85/5/10)
P-8: n-butyl methacrylate / 1H, 1H, 2H, 2H-perfluorodecyl acrylate / acrylic acid copolymer (75/20/5)
P-9: Methyl methacrylate / n-butyl acrylate / acrylic acid copolymer (50/45/5
P-10: Isobutyl methacrylate / polyethylene glycol monomethyl ether (ethyleneoxy chain repeat number 9) methacrylate ester / acrylic acid copolymer (80/10/10)
P-11: Styrene / ethyl methacrylate / methacrylic acid copolymer (30/62/8)
P-12: Styrene / ethyl methacrylate / methacrylic acid copolymer (40/45/15)

  The content of the resin dispersant in the water-based inkjet recording ink according to this embodiment may be determined according to the dispersibility of the specific compound. The content of the resin dispersant in the aqueous inkjet recording ink is, for example, in the range of 0.1% by mass to 10% by mass and in the range of 0.3% by mass to 7% by mass with respect to the entire ink. More preferably. If the content of the resin dispersant is less than 0.1% by mass, the specific compound may not be sufficiently dispersed. If the content exceeds 10% by mass, clogging at the nozzle end, roller offset, storage Deterioration such as offset may occur.

(Color material)
The water-based inkjet recording ink according to this embodiment contains a color material. As the coloring material, pigments and dyes applicable to various inks are used, and pigments are preferable from the viewpoint of light resistance, heat resistance, and the like.

  Specific examples of the pigment include, for example, C.I. I. Pigment Blue 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 13, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 17, 17, 23, 60, 65, 73, 83, 180, C.I. I. Vat cyan 1, 3 and 20 etc., bitumen, cobalt blue, alkali blue lake, phthalocyanine blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue, fast sky blue, indanthrene blue BC cyan pigment, etc. It is done.

  Examples of magenta pigments include C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48, 49, 50, 51, 52, 53, 54, 55, 57, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90 , 112, 114, 122, 123, 163, 184, 202, 206, 207, 209, and pigment violet 19. In addition, C.I. I. Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 30, 49, 81, 82, 83, 84, 100, 109, 121, C . I. Disper thread 9, C.I. I. Basic Red 1, 2, 9, 9, 13, 14, 15, 17, 17, 18, 22, 23, 24, 27, 29, 32, 34, the same 35, 36, 37, 38, 39, 40, etc., bengara, cadmium red, red lead, mercury sulfide, permanent red 4R, risor red, pyrazolone red, watching red, calcium salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rotamin Lake B, Alizarin Lake, Brilliant Carmine 3B and the like.

  Examples of the yellow pigment include C.I. I. Pigment Yellow 2, 3, 15, 15, 16, 17, 97, 180, 185, 139, and the like.

  Examples of the black pigment used in the black ink include carbon pigments such as carbon black. Since the carbon pigment has a high near-infrared absorbing ability, it is not necessary to add a specific compound separately from the carbon pigment. In such a case, the carbon pigment is a component that serves both as a colorant and a specific compound.

  The content of the color material in the water-based inkjet recording ink according to this embodiment may be determined according to the hue required for the ink. The content of the color material is, for example, in the range of 0.5% by mass to 10% by mass and preferably in the range of 1% by mass to 8% by mass with respect to the entire ink. When the content of the color material is less than 0.5% by mass, the color development on the recording medium may be insufficient. When the content exceeds 10% by mass, the ink storage life is shortened or the head is clogged. May occur.

(PH adjuster)
In order to adjust the pH of the water-based inkjet recording ink according to this embodiment to a range of 6.5 to 8.5, a pH adjuster may be used. The pH adjuster is not particularly limited as long as it can adjust the pH to a range of 6.5 or more and 8.5 or less, but various pH buffers may be used. Examples of the pH buffer include Good buffer, sodium dihydrogen phosphate-disodium hydrogen phosphate, potassium dihydrogen phosphate-sodium hydroxide, boric acid-potassium chloride-sodium hydroxide, and the like. In view of stability over time, suppression of head member deterioration, and the like, a good buffer is preferable. Examples of the good buffer include ADA, PIPES, ACES, collamine hydrochloride, BES, TES, HEPES, acetamidoglycine, tricine, glycinamide, and bicine.

(solvent)
In the water-based inkjet recording ink according to the present embodiment, a water-soluble organic solvent may be used in addition to water. Examples of the water-soluble organic solvent include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-propanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4 -Pentanediol, 1,2-hexanediol, 1,6-hexanediol, glycerin, 1,2,3-butanetriol, 1,2,4-butanetriol, 1,2,6-hexanetriol, petriol, etc. Polyhydric alcohols; ethylene glycol Polyhydric alcohol alkyl ethers such as ethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether; ethylene glycol monophenyl Polyhydric alcohol aryl ethers such as ether and ethylene glycol monobenzyl ether; 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam, etc. A nitrogen-containing heterocyclic compound; formamide, N-methylformamide, N, N-dimethyl Amides such as formamide; amines such as monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine and triethylamine; sulfur-containing compounds such as dimethylsulfoxide, sulfolane and thiodiethanol; propylene carbonate, ethylene carbonate and the like It is done. These may be used individually by 1 type and may use 2 or more types together.

  Among these, in consideration of the suppression of jetting properties due to solubility and water evaporation, propylene glycol, diethylene glycol monoisopropyl ether, 1,2-hexanediol, ethylene glycol, diethylene glycol, 1,3-propanediol, diethylene glycol monobutyl ether Diethylene glycol mono n-propyl ether, propylene glycol monomethyl ether, 2-pyrrolidone, 2,3-butanediol and the like are preferable.

  The water content in the water-based inkjet recording ink according to this embodiment is, for example, in the range of 40% by mass to 90% by mass with respect to the entire ink. The content of the water-soluble organic solvent in the water-based inkjet recording ink according to this embodiment is, for example, in the range of 3% by mass to 50% by mass with respect to the entire ink, and is 5% by mass to 40% by mass. A range is preferable. If the content of the water-soluble organic solvent is less than 3% by mass, the nozzle may be easily dried and defective ejection of droplets may occur. If the content exceeds 50% by mass, the ink viscosity increases, and an appropriate viscosity range is obtained. May be exceeded.

(Other ingredients)
The water-based inkjet recording ink according to this embodiment includes a pigment dispersant for dispersing a pigment as a color material, an emulsion, a surfactant, and other components in addition to the specific compound and the color material described above. Also good. About other components, a conventionally well-known various component can be used in a well-known addition ratio.

  Examples of the pigment dispersant include a polymer dispersant, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant described later. In particular, a polymer dispersant is preferable in terms of pigment dispersion stability.

  As the polymer dispersant, a polymer having a hydrophilic structure portion and a hydrophobic structure portion is preferably used. As the polymer having a hydrophilic structure part and a hydrophobic structure part, for example, a condensation polymer and an addition polymer are used. Examples of the condensation polymer include known polyester dispersants. Examples of the addition polymer include addition polymers of monomers having an α, β-ethylenically unsaturated group. By copolymerizing a monomer having an α, β-ethylenically unsaturated group having a hydrophilic group and a monomer having an α, β-ethylenically unsaturated group having a hydrophobic group A polymeric dispersant is obtained. A homopolymer of a monomer having an α, β-ethylenically unsaturated group having a hydrophilic group is also used.

  Monomers having an α, β-ethylenically unsaturated group having a hydrophilic group include monomers having a carboxyl group, a sulfonic acid group, a hydroxyl group, a phosphoric acid group, such as acrylic acid, methacrylic acid, and croton. Acid, itaconic acid, itaconic acid monoester, maleic acid, maleic acid monoester, fumaric acid, fumaric acid monoester, vinyl sulfonic acid, styrene sulfonic acid, sulfonated vinyl naphthalene, vinyl alcohol, acrylamide, methacryloxyethyl phosphate, bis Examples include methacryloxyethyl phosphate, methacryloxyethyl phenyl acid phosphate, ethylene glycol dimethacrylate, and diethylene glycol dimethacrylate.

  Examples of the monomer having an α, β-ethylenically unsaturated group having a hydrophobic group include styrene derivatives such as styrene, α-methylstyrene, vinyltoluene, vinylcyclohexane, vinylnaphthalene, vinylnaphthalene derivatives, and alkyl acrylate esters. Methacrylic acid alkyl ester, methacrylic acid phenyl ester, methacrylic acid cycloalkyl ester, crotonic acid alkyl ester, itaconic acid dialkyl ester, maleic acid dialkyl ester and the like.

  Examples of preferred copolymers as the polymer dispersant include styrene-styrene sulfonic acid copolymer, styrene-maleic acid copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid copolymer, vinyl naphthalene- Maleic acid copolymer, vinyl naphthalene-methacrylic acid copolymer, vinyl naphthalene-acrylic acid copolymer, alkyl acrylate ester-acrylic acid copolymer, alkyl methacrylate ester-methacrylic acid copolymer, styrene-methacrylic acid Alkyl ester-methacrylic acid copolymer, styrene-alkyl acrylate ester-acrylic acid copolymer, styrene-phenyl methacrylate-methacrylic acid copolymer, styrene-methacrylic acid cyclohexyl ester-methacrylic acid copolymer, or these Of salt It is. Moreover, you may copolymerize the monomer which has a polyoxyethylene group and a hydroxyl group with these polymers.

  Among these, a polymer dispersant selected from the group consisting of a styrene-acrylic acid copolymer and a styrene-acrylate copolymer is preferable, a styrene-acrylate copolymer is more preferable, and a styrene- Particularly preferred are alkali metal acrylate copolymers.

  These polymer dispersants may be used alone or in combination of two or more. Although the content of the polymer dispersant varies greatly depending on the pigment, it cannot be generally stated, but it is preferably 0.1% by mass or more and 100% by mass or less based on the pigment.

  Examples of the surfactant include an anionic surfactant, a nonionic surfactant, a cationic surfactant, an amphoteric surfactant, and the like, and preferably an anionic surfactant, a nonionic surfactant, More preferred is a nonionic surfactant.

As the nonionic surfactant, for example, it is preferable to include a surfactant having an HLB (hydrophilic group / hydrophobic group balance “Hydrophile-Lipophile Balance”) of 14 or less. The surface tension of the water-based ink can be easily adjusted by adjusting the amount of the surfactant having an HLB of 14 or less, or by using a plurality of surfactants having different HLB. The HLB (hydrophilic group / hydrophobic group balance “Hydrophile-Lipophile Balance”) is defined by the following formula (Griffin method).
HLB = 20 × (sum of formula weight / molecular weight of hydrophilic part)

Examples of such a surfactant include at least one selected from the group consisting of an ethylene oxide adduct of acetylene glycol and a polyether-modified silicone. The ethylene oxide adduct of acetylene glycol is, for example, an —O— (CH ₂ CH ₂ O) _n —H structure in which ethylene oxide is added to at least one hydroxyl group of acetylene glycol (for example, n is 1 to 30). A compound having an integer).

  Examples of commercially available acetylene glycol ethylene oxide adducts (numbers in parentheses indicate HLB catalog values) include, for example, Olphine E1004 (from 7 to 9), Olphine E1010 (from 13 to 14), Olphine EXP. . 4001 (8 to 11), Olphin EXP. 4123 (11 to 14), Olphin EXP. 4300 (from 10 to 13), Surfinol 104H (4), Surfinol 420 (4), Surfinol 440 (8), Dinol 604 (8) (all manufactured by Nissin Chemical Industry Co., Ltd.) and the like. .

  The polyether-modified silicone is, for example, a compound in which a polyether group is bonded to a silicone chain (polysiloxane main chain) in a graft form or a block form. Examples of the polyether group include a polyoxyethylene group and a polyoxypropylene group. The polyether group may be, for example, a polyoxyalkylene group in which an oxyethylene group and an oxypropylene group are added in a block form or randomly.

  As commercial products of polyether-modified silicone (the numbers in parentheses indicate catalog values of HLB), Silface SAG002 (12), Silface SAG503A (11), Silface SAG005 (7) (the above, Nissin) Chemical Industry Co., Ltd.).

  Further, other nonionic surfactants other than acetylene glycol ethylene oxide adduct and polyether-modified silicone may be used. Other nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester. , Polyoxyethylene glycerin fatty acid ester, polyglycerin fatty acid ester, sucrose fatty acid ester, polyoxyethylene alkylamine, polyoxyethylene fatty acid amide, alkyl alkanolamide, polyethylene glycol polypropylene glycol block copolymer, acetylene glycol and the like.

  Among these, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid alkyl Roll amide, polyethylene glycol polypropylene glycol block copolymer, and acetylene glycol are preferred.

  Other nonionic surfactants include silicone surfactants such as polysiloxane oxyethylene adducts; fluorine-based surfactants such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and oxyethylene perfluoroalkyl ethers. Agents; biosurfactants such as spicrispolic acid, rhamnolipid, lysolecithin; and the like.

  Examples of the anionic surfactant include alkyl benzene sulfonate, alkyl phenyl sulfonate, alkyl naphthalene sulfonate, higher fatty acid salt, sulfate of higher fatty acid ester, sulfonate of higher fatty acid ester, higher alcohol ether. And sulfates and sulfonates thereof, higher alkyl sulfosuccinates, polyoxyethylene alkyl ether carboxylates, polyoxyethylene alkyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, and the like.

  Among these, as anionic surfactants, dodecylbenzenesulfonate, isopropylnaphthalenesulfonate, monobutylphenylphenol monosulfonate, monobutylbiphenylsulfonate, monobutylbiphenylsulfonate, dibutylphenylphenol Disulfonates are preferred.

  The surfactant may be used alone or in combination of two or more.

  As an emulsion, a polyurethane emulsion etc. are mentioned, for example.

<Water-based inkjet recording ink set>
The ink set for water-based inkjet recording according to the present embodiment includes a black ink containing carbon black as a color material, and one or a plurality of color inks that are the water-based inkjet recording ink and the color material is a chromatic color material. It consists of. “Chromatic color” refers to a color that does not have a hue and saturation such as white, black, and gray, and has a hue and saturation in addition to lightness. The water-based inkjet recording ink set includes black ink containing carbon black as a coloring material, and one or more of, for example, cyan ink, magenta ink, and yellow ink, which are the water-based inkjet recording inks. .

<Inkjet recording apparatus and inkjet recording method>
The ink jet recording apparatus and the ink jet recording method according to the present embodiment are an ink jet recording apparatus and an ink jet recording method to which the water-based ink jet recording ink or the water-based ink jet recording ink set is applied.

  The ink jet recording apparatus according to the present embodiment discharges the water-based ink jet recording ink or the water-based ink jet recording ink set to apply the ink to the recording medium, and the ink applied to the recording medium. And a near-infrared laser light-emitting device that irradiates a near-infrared laser having a center wavelength in the range of 750 nm to 950 nm.

  In the ink jet recording method according to this embodiment, after the ink for water-based ink jet recording or the ink set for water-based ink jet recording is ejected from a recording head and applied to a recording medium, the center wavelength is in the range of 750 nm to 950 nm. This is a method of recording by irradiating an infrared laser and drying the ink.

  The ink jet recording apparatus and the ink jet recording method according to the present embodiment are suitably applied as an ink jet recording apparatus and an ink jet recording method for high-speed printing.

  As examples of the ink jet recording apparatus and the ink jet recording method on which the water-based ink jet recording ink or the water-based ink jet recording ink set is mounted, for example, the following configurations and methods (1) to (3) are conceivable.

  (1) A configuration and method for performing recording by repeatedly irradiating a near-infrared laser having a center wavelength in the range of 750 nm or more and 950 nm or less after applying ink to a recording medium for each color ink.

  For example, after printing black ink on a recording medium with a black head, the black ink is dried by irradiating a near-infrared laser. Thereafter, cyan ink printing → laser irradiation → magenta ink printing → laser irradiation → yellow ink printing → laser irradiation, and printing and laser irradiation are repeated. The order of printing the ink is not limited to this, and the position of the laser irradiation device in conveying the recording medium is not limited.

  (2) For each color ink, after applying the ink to the recording medium, the near-infrared laser having a center wavelength in the range of 750 nm to 950 nm is repeatedly applied, and the ink to be recorded last is applied to the recording medium. After that, a configuration and method for drying the ink by heating the recording medium without irradiating the near infrared laser.

  For example, black ink printing → laser irradiation → cyan ink printing → laser irradiation → magenta ink printing → laser irradiation → yellow ink printing. After yellow ink is applied to the recording medium, the recording medium is not irradiated with near infrared laser. Is heated to dry the ink. The heating may be performed by drying the entire surface of the recording medium through a heating device such as a heater dryer. The ink printing order is not limited to this, and the positions of the laser irradiation device and the heating device in recording medium conveyance are not limited.

  In the case of (2), the last applied ink may not contain a specific compound. For example, if a specific compound affects the yellow coloration, the last ink to be printed is a yellow ink, and the yellow ink does not contain the specific compound. Can be avoided.

  (3) A configuration and method of irradiating a near-infrared laser having a center wavelength in the range of 750 nm or more and 950 nm or less after applying ink of all colors to the recording medium.

  For example, black ink printing → cyan ink printing → magenta ink printing → yellow ink printing → laser irradiation. The ink printing order is not limited to this.

  Hereinafter, an ink jet recording apparatus according to the present embodiment will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram illustrating an example of an ink jet recording apparatus according to the present embodiment. The ink jet recording apparatus 1 according to this embodiment shown in FIG. 1 is based on the configuration and method (1) above. The ink jet recording apparatus 1 includes a transport unit 10 for transporting a recording medium P, and four ink jet recording heads 20a, 20b, 20c, which apply ink to the recording medium by discharging a plurality of colors of ink onto the recording medium P. As a near-infrared laser light emitting device that irradiates a near-infrared laser having a center wavelength in the range of 750 nm to 950 nm with respect to 20d and the color-specific ink ejected on the recording medium P, four laser irradiation means 30a , 30b, 30c, 30d.

  The conveying means 10 is an endless belt 12 stretched by rollers 14a and 14b. The belt 12 stretched by the rollers 14a and 14b includes at least a region (ink ejection region) facing the nozzle surface of each of the inkjet recording heads 20a, 20b, 20c, and 20d, and laser irradiation means 30a, 30b, and 30c. , 30d is configured so that the near-infrared laser irradiation area is substantially horizontal. The belt 12 has a width larger than the maximum width of the recording medium P targeted by the inkjet recording apparatus 1.

  A belt driving motor (not shown) is connected to one or both of the rollers 14a and 14b, and the belt 12 rotates and moves in the direction of the arrow in FIG. With the rotational movement of the belt 12 as described above, the recording medium P such as recording paper supplied on the belt 12 is conveyed from one side (right side) to the other side (left side) in FIG.

  The four inkjet recording heads 20a, 20b, 20c, and 20d are arranged from the upstream side to the downstream side in the conveyance direction of the recording medium P, and ink tanks 22a, 22b, 22c, which store a plurality of color inks by color. 22d and pipes 24a, 24b, 24c, and 24d, respectively. The color-specific inks supplied from the ink tanks 22a, 22b, 22c, and 22d are ejected in that order from the inkjet recording heads 20a, 20b, 20c, and 20d to the recording medium P that is transported by the transporting unit 10. .

  The inkjet recording heads 20a, 20b, 20c, and 20d are, for example, a head 20a that discharges black ink, a head 20b that discharges cyan ink, a head 20c that supplies magenta ink from the upstream side in the conveyance direction of the recording medium P, and yellow. And a head 20d for ejecting ink. The combination of the inks ejected from the respective ink jet recording heads 20a, 20b, 20c, and 20d is not limited to the above-described configuration, and may be any configuration that ejects a plurality of colors of ink for each color. The configuration may further include a head that ejects ink having a different hue (that is, a configuration in which five or more heads are present), and the hue and order (ejection order) of the ink to be ejected are different from the above configuration. It may be a thing.

  For each ink jet recording head 20a, 20b, 20c, 20d, for example, a line type ink jet recording head having a width equal to or larger than the width of the recording medium P targeted by the ink jet recording apparatus 1 is applied. A conventional scanning ink jet recording head may be applied. Also, conventionally known methods such as a piezoelectric element driving type and a heating element driving type are applied as the ink discharging method from each of the ink jet recording heads 20a, 20b, 20c, and 20d.

  The four laser irradiation means 30a, 30b, 30c, and 30d are arranged on the downstream side in the transport direction of the recording medium P with respect to each of the inkjet recording heads 20a, 20b, 20c, and 20d. Each of the laser irradiation means 30a, 30b, 30c, 30d has a function of irradiating a near infrared laser, and the laser control unit 32 controls the irradiation energy of the near infrared laser, the irradiation timing, the oscillation wavelength, and the like.

  The laser irradiation means 30a, 30b, 30c, and 30d may be any near-infrared laser having an oscillation wavelength in the range of 750 nm to 950 nm, preferably 800 nm to 850 nm, with no particular limitation. Is done. As such laser irradiation means, a near-infrared laser such as a semiconductor laser, a solid-state laser, a gas laser, or a dye laser is applied, and a high-power LED may be used if a condensing optical system is attached. More specifically, a semiconductor array laser with an oscillation wavelength of 900 nm, a semiconductor array laser with an oscillation wavelength of 810 nm, a semiconductor array laser with an oscillation wavelength of 840 nm, a semiconductor array laser with an oscillation wavelength of 940 nm, a titanium sapphire laser with an oscillation wavelength of 800 nm, and the like are applied. Is done.

  Irradiation conditions of the near-infrared laser by each of the laser irradiation means 30a, 30b, 30c, and 30d are not particularly limited as long as the ink can be dried, but the ink discharged onto the recording medium P is not limited. It is preferable that energy can be irradiated as uniformly as possible.

For example, the near infrared lasers may be arranged in a line in a direction substantially perpendicular to the conveyance direction of the recording medium P. Depending on the conveyance speed of the recording medium P and the output of the laser, the near infrared laser may be a scan type. There may be. In addition, examples of the near-infrared laser irradiation conditions include the following. That is, when the line-shaped beam irradiation is performed on the recording medium P, the line-shaped irradiation is performed depending on the width between the recording medium P conveyance direction and the direction substantially perpendicular to the conveyance direction (that is, the length and width of the recording medium P). What is necessary is just to determine an irradiation area | region. Specifically, the width in the direction substantially perpendicular to the conveyance direction of the recording medium P (the width of the recording medium P is the width of the paper or the area where ink is ejected, and the width in the conveyance direction (the width of the recording medium P)). (Length) is set according to the conveyance speed and the target irradiation time (width = conveying speed × irradiation time), and the irradiation energy by the near-infrared laser may be determined according to the ink ejection amount and the like. for example, if the discharge amount of the common ink is referred to as being 1 g / cm ² or more 30 g / cm ² or less in the range in energy ink absorbs, the degree 0.3 J / cm ² or more 10J / cm ² or less The irradiation energy may be adjusted so that the absorption rate of the laser beam of the ink is A, and the range is 0.3 / A (J / cm ² ) or more and 10 / A (J / cm ² ) or less. The absorption rate A is the ink ejection (dryness). Depending on the order in which it is applied, it is preferably selected from the range of 10% to 100%.

  In addition, the ink is landed on the recording medium P from the viewpoint of suppressing the permeation and diffusion of the ink into the recording medium P before the solvent in the ink evaporates and the occurrence of the droplet ejection interference between the ink droplets. After that, it is preferable that the laser irradiation means 30a, 30b, 30c, 30d immediately irradiate the near infrared laser. For example, it is preferable that the infrared laser is irradiated within 100 milliseconds after the start of ink ejection. More specifically, since the ease with which the ink penetrates into the recording medium P varies depending on the type of the recording medium P, for example, if the recording medium P is a low permeability recording medium such as a coated paper for printing, etc. In the case of a permeable recording medium such as rough paper within 100 milliseconds after the start of ink ejection, the near infrared laser is preferably irradiated within a few milliseconds after the start of ink ejection. For this purpose, it is preferable that the laser irradiation means 30a, 30b, 30c, and 30d and the ink jet recording heads 20a, 20b, 20c, and 20d are arranged close to each other. Further, unlike the example of the ink jet recording apparatus 1, the laser irradiation means and the ink jet recording head may be integrated for each color, or by using an optical system such as a mirror, the laser irradiation unit and the ink landing The configuration may be such that the unit is close to the unit.

  Subsequently, an image forming process by the ink jet recording apparatus 1 will be described. In the ink jet recording apparatus 1, first, the recording medium P is supplied onto the belt 12 that is rotationally driven by a supply unit (not shown). Subsequently, on the supplied recording medium P, ink (for example, black ink) droplets are ejected by the inkjet recording head 20a based on predetermined image information and land on the recording medium P. The ink that has landed on the recording medium P is immediately irradiated with a near-infrared laser by the laser irradiation means 30a. As a result, the ink dries quickly, so that the penetration and diffusion of the ink into the recording medium P and the occurrence of droplet ejection interference between the ink droplets are suppressed.

  In the same manner as described above, ink ejection by the inkjet recording heads 20b, 20c, and 20d and near-infrared laser irradiation by the laser irradiation means 30b, 30c, and 30d are performed, respectively, and inks of each color (for example, cyan ink) , Magenta ink, yellow ink). Also at this time, since the ink dries quickly, the penetration of the ink into the recording medium P, the occurrence of diffusion, the occurrence of droplet ejection interference between the ink droplets, and the like are suppressed. As described above, image formation is performed by the inkjet recording apparatus 1.

  FIG. 2 is a schematic configuration diagram illustrating another example of the ink jet recording apparatus according to the present embodiment. The ink jet recording apparatus 3 according to this embodiment shown in FIG. 2 is based on the configuration and method (2) above. The ink jet recording apparatus 3 includes a transport unit 10 for transporting the recording medium P, and four ink jet recording heads 20a, 20b, 20c, which apply ink to the recording medium by discharging a plurality of colors of ink onto the recording medium P. As a near-infrared laser emitting device that irradiates a near-infrared laser having a center wavelength in the range of 750 nm to 950 nm with respect to 20d and the color-specific ink ejected on the recording medium P, three laser irradiation means 30a , 30b, 30c and a heating device 40 for heating the recording medium P.

  The conveying means 10 is an endless belt 12 stretched by rollers 14a and 14b. The belt 12 stretched by the rollers 14a and 14b includes at least a region (ink ejection region) facing the nozzle surface of each of the inkjet recording heads 20a, 20b, 20c, and 20d, and laser irradiation means 30a, 30b, and 30c. The near infrared laser irradiation area is configured to be substantially horizontal. The belt 12 has a width larger than the maximum width of the recording medium P targeted by the ink jet recording apparatus 3.

  A belt driving motor (not shown) is connected to one or both of the rollers 14a and 14b, and the belt 12 rotates and moves in the direction of the arrow in FIG. With the rotational movement of the belt 12 as described above, the recording medium P such as recording paper supplied on the belt 12 is conveyed from one side (right side) to the other side (left side) in FIG.

  The four inkjet recording heads 20a, 20b, 20c, and 20d are arranged from the upstream side to the downstream side in the conveyance direction of the recording medium P, and ink tanks 22a, 22b, 22c, which store a plurality of color inks by color. 22d and pipes 24a, 24b, 24c, and 24d, respectively. The color-specific inks supplied from the ink tanks 22a, 22b, 22c, and 22d are ejected in that order from the inkjet recording heads 20a, 20b, 20c, and 20d to the recording medium P that is transported by the transporting unit 10. .

  The inkjet recording heads 20a, 20b, 20c, and 20d are, for example, a head 20a that discharges black ink, a head 20b that discharges cyan ink, a head 20c that supplies magenta ink from the upstream side in the conveyance direction of the recording medium P, and yellow. And a head 20d for ejecting ink. The combination of the inks ejected from the respective ink jet recording heads 20a, 20b, 20c, and 20d is not limited to the above-described configuration, and may be any configuration that ejects a plurality of colors of ink for each color. The configuration may further include a head that ejects ink having a different hue (that is, a configuration in which five or more heads are present), and the hue and order (ejection order) of the ink to be ejected are different from the above configuration. It may be a thing.

  The three laser irradiation means 30a, 30b, and 30c are arranged on the downstream side in the conveyance direction of the recording medium P with respect to each of the inkjet recording heads 20a, 20b, and 20c. Each of the laser irradiation means 30a, 30b, and 30c has a function of irradiating a near infrared laser, and the laser control unit 32 controls the irradiation energy of the near infrared laser, the irradiation timing, the oscillation wavelength, and the like. Further, a heating device 40 is disposed on the downstream side in the conveyance direction of the recording medium P with respect to the inkjet recording head 20d.

  An image forming process by the ink jet recording apparatus 3 will be described. In the ink jet recording apparatus 3, first, the recording medium P is supplied onto the rotationally driven belt 12 by a supply unit (not shown). Subsequently, on the supplied recording medium P, ink (for example, black ink) droplets are ejected by the inkjet recording head 20a based on predetermined image information and land on the recording medium P. The ink that has landed on the recording medium P is immediately irradiated with a near-infrared laser by the laser irradiation means 30a. As a result, the ink dries quickly, so that the penetration and diffusion of the ink into the recording medium P and the occurrence of droplet ejection interference between the ink droplets are suppressed.

  In the same manner as described above, ink ejection by the ink jet recording heads 20b and 20c and near-infrared laser irradiation by the laser irradiation means 30b and 30c are performed, respectively, and ink of each color (for example, cyan ink and magenta ink). An image is formed. Also at this time, since the ink dries quickly, the penetration of the ink into the recording medium P, the occurrence of diffusion, the occurrence of droplet ejection interference between the ink droplets, and the like are suppressed. Subsequently, after the ink is ejected by the ink jet recording head 20d, the recording medium P is sent to the heating device 40, and the entire surface of the recording medium P is dried to form an image with ink (for example, yellow ink). Is done. As described above, after the ink to be recorded last (for example, yellow ink) is applied to the recording medium P, the recording medium P is heated without being irradiated with the near-infrared laser to dry the ink. As described above, image formation is performed by the ink jet recording apparatus 3.

  The heating device 40 is not particularly limited as long as it can dry the entire surface of the recording medium P, and examples thereof include a far infrared heater dryer, a drum heater, a carbon heater, and a halogen heater. .

  According to the configuration and method of the ink jet recording apparatus 3, for example, when a specific compound affects yellow coloring, the last ink to be printed is a yellow ink, and the yellow ink does not include the specific compound. In this way, the influence of the specific compound on the coloring of yellow can be avoided.

  FIG. 3 is a schematic configuration diagram illustrating another example of the ink jet recording apparatus according to the present embodiment. The ink jet recording apparatus 5 according to this embodiment shown in FIG. 3 is based on the configuration and the method (3). The ink jet recording apparatus 5 includes a transport unit 10 for transporting the recording medium P, and four ink jet recording heads 20a, 20b, 20c, which apply ink to the recording medium by ejecting a plurality of colors of ink onto the recording medium P. 20d and one laser irradiation means 30 as a near-infrared laser light emitting device that irradiates the ink ejected on the recording medium P with a near-infrared laser having a center wavelength in the range of 750 nm to 950 nm. .

  The conveying means 10 is an endless belt 12 stretched by rollers 14a and 14b. The belt 12 stretched by the rollers 14a and 14b has at least a region (ink ejection region) facing the nozzle surfaces of the respective ink jet recording heads 20a, 20b, 20c, and 20d, and a near infrared by the laser irradiation unit 30. The laser irradiation area is configured to be substantially horizontal. The belt 12 has a width larger than the maximum width of the recording medium P targeted by the inkjet recording apparatus 5.

  A belt driving motor (not shown) is connected to one or both of the rollers 14a and 14b, and the belt 12 rotates and moves in the direction of the arrow in FIG. With the rotational movement of the belt 12 as described above, the recording medium P such as recording paper supplied onto the belt 12 is conveyed from one side (right side) to the other side (left side) in FIG.

  The four inkjet recording heads 20a, 20b, 20c, and 20d are arranged from the upstream side to the downstream side in the conveyance direction of the recording medium P, and ink tanks 22a, 22b, 22c, which store a plurality of color inks by color. 22d and pipes 24a, 24b, 24c, and 24d, respectively. The color-specific inks supplied from the ink tanks 22a, 22b, 22c, and 22d are ejected in that order from the inkjet recording heads 20a, 20b, 20c, and 20d to the recording medium P that is transported by the transporting unit 10. .

  The inkjet recording heads 20a, 20b, 20c, and 20d are, for example, a head 20a that discharges black ink, a head 20b that discharges cyan ink, a head 20c that supplies magenta ink from the upstream side in the conveyance direction of the recording medium P, and yellow. And a head 20d for ejecting ink. The combination of the inks ejected from the respective ink jet recording heads 20a, 20b, 20c, and 20d is not limited to the above-described configuration, and may be any configuration that ejects a plurality of colors of ink for each color. The configuration may further include a head that ejects ink having a different hue (that is, a configuration in which five or more heads are present), and the hue and order (ejection order) of the ink to be ejected are different from the above configuration. It may be a thing.

  The laser irradiation means 30 is arranged on the downstream side with respect to the ink jet recording head 20d on the most downstream side in the conveyance direction of the recording medium P. The laser irradiation means 30 has a function of irradiating a near infrared laser, and the laser control unit 32 controls the irradiation energy of the near infrared laser, the irradiation timing, the oscillation wavelength, and the like.

  An image forming process by the ink jet recording apparatus 5 will be described. In the ink jet recording apparatus 5, first, the recording medium P is supplied onto the rotationally driven belt 12 by a supply unit (not shown). Subsequently, on the supplied recording medium P, ink (for example, black ink) droplets are ejected by the inkjet recording head 20a based on predetermined image information and land on the recording medium P.

  In the same manner as described above, ink is ejected by the ink jet recording heads 20b, 20c, and 20d, and an image of each color ink (for example, cyan ink, magenta ink, yellow ink) is formed. The ink that has landed on the recording medium P is irradiated with a near-infrared laser by the laser irradiation means 30. As a result, the ink dries quickly, so that the penetration and diffusion of the ink into the recording medium P and the occurrence of droplet ejection interference between the ink droplets are suppressed. As described above, image formation is performed by the ink jet recording apparatus 5.

  Of the configurations and methods of the ink jet recording apparatuses 1, 3, 5, that is, the above (1), (2), and (3), ink permeation into the recording medium P, occurrence of diffusion, and droplet ejection between ink droplets The inkjet recording apparatus 1, that is, the configuration and method of (1), and the inkjet recording apparatus 3, that is, the configuration and method of (2) are more preferable in terms of further suppressing the occurrence of interference. The recording apparatus 1, that is, the configuration and method of (1) above are most preferable.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

[Specific compound (A)]
Specific compound (A) according to the following scheme (in the above general formula (I), R ^a , R ^b , R ^c and R ^d are represented by the general formula (IR), R ¹ is a methyl group, and n is 0 A compound having a structure is synthesized.

  A three-necked flask was equipped with a Dean-Stark trap, a reflux condenser, a stirring seal, and a stirring rod to prepare a reaction vessel. 2,2,8,8-Tetramethyl-3,6-nonadiin-5-ol and cyclohexane were placed in a reaction vessel. Manganese (IV) oxide powder was added, stirred with a three-one motor, and heated to reflux. Water formed during the reaction was removed by azeotropic distillation. It was confirmed by thin layer chromatography that there was no 2,2,8,8-tetramethyl-3,6-nonadiin-5-ol remaining. The reaction mixture was allowed to cool and then filtered under reduced pressure to obtain a yellow filtrate (F1). The solid obtained by filtration was transferred to another container, ethyl acetate was added, and the operation of ultrasonic dispersion and filtration was repeated 4 times to obtain an ethyl acetate extract (F2). The ethyl acetate extract (F2) and the filtrate (F1) were mixed and concentrated with a rotary evaporator and then with a vacuum pump to obtain an orange-colored liquid. The orange-colored liquid was distilled under reduced pressure to obtain a pale yellow liquid (Intermediate 1).

  A thermometer and a dropping funnel were installed in a three-necked flask to prepare a reaction vessel. Sodium hydrogen monosulfide n hydrate was added to ethanol, and the mixture was stirred at room temperature (20 ° C.) until dissolved, and then cooled with ice water. When the internal temperature reached 5 ° C., a mixture of intermediate 1 and ethanol was added dropwise little by little. The liquid changed from yellow to orange by the dropwise addition. Since the internal temperature increased due to heat generation, the internal temperature was dropped within the range of 5 ° C. or higher and 7 ° C. or lower while adjusting the dropping amount. Thereafter, the ice water bath was removed, and the mixture was stirred while the temperature was naturally raised at room temperature (20 ° C.). Water was added to the reaction solution, and ethanol was removed by a rotary evaporator. Thereafter, sodium chloride was added until saturation, and the mixture was separated with ethyl acetate to recover the organic phase. The organic phase was washed twice with saturated ammonium chloride and dried over magnesium sulfate. After drying, the solution was concentrated under reduced pressure to recover a brown liquid. This brown liquid was distilled under reduced pressure. A distillate starts to be produced at 200 ° C., but since the first distillate component is not included, the main distillate was selected when the amount of steam increased. A yellow liquid (Intermediate 2) was distilled.

  A stir bar and intermediate 2 were placed in a three-necked flask, and a nitrogen introduction tube and a reflux condenser were attached to replace the nitrogen. Under a nitrogen atmosphere, anhydrous tetrahydrofuran was added with a syringe, and a 1M tetrahydrofuran solution of methylmagnesium bromide (THF) was added dropwise with a syringe while stirring at room temperature (20 ° C.). After completion of the dropwise addition, the reaction solution was heated and stirred and refluxed. The reaction solution was allowed to cool under a nitrogen atmosphere, and then a solution of ammonium bromide dissolved in water was added dropwise while cooling in an ice-water bath. The reaction mixture was further stirred at room temperature (20 ° C.), n-hexane was added, and the mixture was dried over sodium sulfate. After drying, the n-hexane / THF solution was taken out with a syringe and the inorganic layer was washed with ethyl acetate to obtain an extract. The n-hexane / THF solution and the extract from the inorganic layer were mixed, concentrated under reduced pressure, and then vacuum dried to obtain Intermediate 3.

  Under a nitrogen atmosphere, Intermediate 3 and squaric acid were dispersed in a mixed solvent of cyclohexane and isobutanol, and pyridine was added and heated to reflux. Then isobutanol was added and the reaction mixture was further heated to reflux. Water generated during the reaction was removed by azeotropic distillation. The reaction mixture was allowed to cool and then filtered under reduced pressure to remove hardly soluble substances. The filtrate was concentrated on a rotary evaporator. Methanol was added to the residue, heated to 40 ° C, and then cooled to -10 ° C. Crystals were obtained by filtration, and this was vacuum-dried to obtain the specific compound (A).

<Example 1>
[Cyan ink 1]
Coloring material (pigment) Pigment Blue 15: 4 4% by mass
Styrene-methacrylic acid ester-methacrylic acid sodium salt copolymer (pigment dispersant)
0.4% by mass
Near-infrared absorptive aqueous dispersion (content of specific compound of the following structure (A) 0.24% by mass, resin dispersant PV-12 (weight average molecular weight: 32000, acid value: 34 mgKOH / g) 4.8% by mass) 21% by mass
Propylene glycol 10% by mass
Diethylene glycol monoisopropyl ether 5% by mass
1,2-hexanediol 1% by mass
Olfine E1010 (surfactant) 0.5% by mass
Olfine E1004 (surfactant) 0.5% by mass
pH buffer (BES / NaOH aqueous solution) 2% by mass
Pure water 55.6% by mass

  After mixing the above components, the mixture was filtered with a 5 μm filter to obtain cyan ink 1. The ink pH was 7.7.

[Magenta ink 1]
Color material (pigment) Pigment Red 122 6 mass%
Styrene-methacrylic acid ester-methacrylic acid sodium salt copolymer (pigment dispersant)
0.6% by mass
Near-infrared absorbing aqueous dispersion (content of specific compound of structure (A) 0.24 mass%, resin dispersant PV-12 4.8 mass%) 21 mass%

Propylene glycol 10% by mass
Diethylene glycol monoisopropyl ether 5% by mass
1,2-hexanediol 1% by mass
Olfine E1010 0.6% by mass
Olfine E1004 0.4% by mass
pH buffer (BES / NaOH aqueous solution) 2% by mass
Pure water 53.4% by mass

  After mixing the above components, the mixture was filtered with a 5 μm filter to obtain magenta ink 1. The ink pH was 7.4.

[Yellow ink 1]
Color material (pigment) Pigment Yellow 74 4% by mass
Styrene-methacrylic acid ester-methacrylic acid sodium salt copolymer (pigment dispersant)
0.4% by mass
Near-infrared absorbing aqueous dispersion (content of specific compound of structure (A) 0.24 mass%, resin dispersant PV-12 4.8 mass%) 21 mass%
Propylene glycol 12% by mass
Diethylene glycol monoisopropyl ether 5% by mass
1,2-hexanediol 1% by mass
Olfine E1010 0.6% by mass
Olfine E1004 0.4% by mass
pH buffer (BES / NaOH aqueous solution) 2% by mass
Pure water 53.6% by mass

  After mixing the above components, the mixture was filtered with a 5 μm filter to obtain yellow ink 1. The ink pH was 8.0.

[Black ink 1]
Color material (pigment) Carbon black 5% by mass
Styrene-acrylic acid ester-acrylic acid Na salt copolymer (pigment dispersant)
0.5% by mass
Propylene glycol 15% by mass
Diethylene glycol monoisopropyl ether 4% by mass
1,2-hexanediol 1.5% by mass
Polyacrylate emulsion (solid content 25%) 3% by mass
Olfine E1010 0.6% by mass
Olfine E1004 0.4% by mass
pH buffer (BES / NaOH aqueous solution) 2% by mass
70% by mass of pure water

  After mixing the above components, the mixture was filtered with a 5 μm filter to obtain black ink 1.

[Evaluation]
(Image unevenness)
Using an ink set including cyan ink 1, magenta ink 1, yellow ink 1, and black ink 1, printing is performed as a low-penetration recording medium with the ink jet recording apparatus (near infrared laser peak wavelength: 808 nm) shown in FIG. Recording was performed on an OK top coat + (manufactured by Oji Paper Co., Ltd.), which is a coated paper for printing. The single color and secondary color solid patches were visually evaluated according to the following criteria. The result of Example 1 was ◯. The results are summarized in Table 1.
○: The entire solid patch appears to be uniform. Δ: Although slight graininess degradation is observed, there is no obvious unevenness. ×: White stripes can be visually recognized.

(Ink storage stability)
The ink was stored in a sealed state at 50 ° C. for 1 month. Ink pH after storage, viscosity, surface tension, volume average particle diameter, number of coarse particles> 0.5 μm, peak wavelength of spectral spectra of pigments and specific compounds and their absorbance are compared with before storage and evaluated according to the following criteria did. The rate of change was all <10%. The results are summarized in Table 1.
◯: All change rates are 10% or less △: Change rate of 1 item is more than 10%, 20% or less, remaining items are 10% or less ×: Change rate of 2 or more items is more than 10%, or change of 1 item The rate is over 20%

The ink pH was measured under the condition of 23 ° C. using a pH measuring device (manufactured by METTLER TOLEDO, MPC227). The viscosity was measured using a viscosity measuring device (manufactured by Toki Sangyo Co., Ltd., TV-20) under conditions of 23 ° C. and a shear rate of 750 s ⁻¹ . The surface tension was measured under the condition of 23 ° C. using a surface tension measuring device (manufactured by Kyowa Interface Science, Wilhelmy CBVP). The volume average particle size was measured under the condition of 23 ° C. using a particle size distribution measuring device (Nikkiso, Nanotrack UPA). The number of coarse particles> 0.5 μm was measured at 23 ° C. using a number counting particle size distribution analyzer (manufactured by PSS, Accusizer 780APS). The peak wavelength of the spectrum and its absorbance were measured using a spectrophotometer (manufactured by JASCO Corporation, V-560) at 23 ° C. The acid value of the resin dispersant was measured by a neutralization titration method defined in JIS K0070: 1992.

<Comparative Example 1>
In place of the ink of Example 1, the pH buffer was changed to sodium bicarbonate-sodium hydroxide, and an ink adjusted to pH = 9.5 was used, and the same evaluation as in Example 1 was performed. The result of the image unevenness was x, and in the ink storage stability evaluation, the volume average particle diameter and the spectral spectrum change rate were> 10%. Since the near-infrared absorption efficiency due to the specific compound was lowered, it is considered that white streaks occurred due to droplet ejection interference between ink droplets on the recording medium before the solvent in the ink evaporated. Further, it is considered that the crystallization of the specific compound has occurred and the volume average particle size has increased.

<Comparative example 2>
Instead of the ink of Example 1, the pH buffer material was changed to potassium dihydrogen phosphate-sodium hydroxide and the ink adjusted to pH = 5.8 was used for the same evaluation as in Example 1. The result of the image unevenness was ◯, but in the ink storage stability evaluation, the viscosity, the number of coarse particles> 0.5 μm, and the change rate of the spectral spectrum change rate were> 20%, and x. It is considered that the absorption spectrum of the color material itself changed, the dispersion stability of the color material and the specific compound in water deteriorated, and aggregates were formed over time.

<Comparative Example 3>
In place of the ink of Example 1, the pH buffer was changed to boric acid-sodium hydroxide and the ink adjusted to pH = 8.6 was used for the same evaluation as in Example 1. The result of image unevenness was x. In the ink storage stability evaluation, the spectral spectrum change rate was> 10% and Δ.

<Comparative Example 4>
In place of the ink of Example 1, the pH buffer was changed to potassium dihydrogen phosphate-sodium hydroxide and the ink adjusted to pH = 6.4 was used for the same evaluation as in Example 1. Although the result of image unevenness was ◯, in the ink storage stability evaluation, the change rate of the number of coarse particles of> 0.5 μm was> 20% and ×.

<Example 2>
[Cyan ink 2]
Coloring material (pigment) Pigment Blue 15: 4 4% by mass
Styrene-methacrylic acid ester-methacrylic acid sodium salt copolymer (pigment dispersant)
0.4% by mass
Near-infrared absorbing aqueous dispersion (content of specific compound of structure (A) 0.24 mass%, resin dispersant PV-05 (weight average molecular weight: 20000, acid value: 16 mg KOH / g) 4.8 mass%) 21% by mass
Propylene glycol 10% by mass
Propylene glycol monopropyl ether 4% by mass
1,2-hexanediol 0.5% by mass
Olfine E1010 0.6% by mass
Olfine E1004 0.4% by mass
pH buffer (BES / NaOH aqueous solution) 1.7% by mass
Pure water 55.6% by mass

  After mixing the above components, the mixture was filtered with a 5 μm filter to obtain cyan ink 2. The ink pH was 7.1. The same evaluation as in Example 1 was performed by replacing the cyan ink 2 in place of the cyan ink 1 in Example 1. The evaluation results were all ◯.

<Example 3>
[Cyan ink 3]
Coloring material (pigment) Pigment Blue 15: 4 4% by mass
Styrene-methacrylic acid ester-methacrylic acid sodium salt copolymer (pigment dispersant)
0.4% by mass
Near-infrared absorbing aqueous dispersion (content of specific compound of structure (A) 0.24% by mass, resin dispersant PV-15 (weight average molecular weight: 27000, acid value: 11 mgKOH / g) 4.8% by mass) 21% by mass
Propylene glycol 10% by mass
Propylene glycol monobutyl ether 3% by mass
1,2-hexanediol 0.5% by mass
Olfine E1010 0.6% by mass
Olfine E1004 0.4% by mass
pH buffer (BES / NaOH aqueous solution) 1.5% by mass
Pure water 55.6% by mass

  After mixing the above components, the mixture was filtered with a 5 μm filter to obtain cyan ink 3. The ink pH was 6.8. The cyan ink 3 was replaced in place of the cyan ink 1 of Example 1, and the same evaluation as in Example 1 was performed. The evaluation results were all ◯.

[Specific compound (B)]
In the synthesis of the specific compound (A), 2,10-dimethyl-4,7-undecadiin-6-ol was used instead of 2,2,8,8-tetramethyl-3,6-nonadiin-5-ol. A specific compound (B) was synthesized in the same procedure except that.

<Example 4>
[Cyan ink 4]
Coloring material (pigment) Pigment Blue 15: 4 4% by mass
Styrene-methacrylic acid ester-methacrylic acid sodium salt copolymer (pigment dispersant)
0.4% by mass
Near-infrared absorptive aqueous dispersion (content of specific compound of structure (B) below 0.24% by mass, resin dispersant PV-12 4.8% by mass) 21% by mass
Propylene glycol 10% by mass
Diethylene glycol monobutyl ether 3% by mass
1,2-hexanediol 0.7% by mass
Olfine E1010 0.5% by mass
Olfine E1004 0.5% by mass
pH buffer (BES / NaOH aqueous solution) 2% by mass
Pure water 57.6% by mass

After mixing the above components, the mixture was filtered with a 5 μm filter to obtain cyan ink 4.
The ink pH was 7.7. The same evaluation as in Example 1 was performed by replacing the cyan ink 4 in place of the cyan ink 1 in Example 1. The evaluation result of image unevenness was ◯, and the ink storage stability evaluation was ◯.

<Example 5>
[Cyan ink 5]
Coloring material (pigment) Pigment Blue 15: 4 4% by mass
Styrene-methacrylic acid ester-methacrylic acid sodium salt copolymer (pigment dispersant)
0.4% by mass
Near-infrared absorbing aqueous dispersion (content of specific compound of structure (A) 0.24% by mass, resin dispersant P-11 (weight average molecular weight: 40000, acid value: 21 mgKOH / g) 4.8% by mass) 21% by mass
Propylene glycol 10% by mass

Dipropylene glycol monoisopropyl ether 4% by mass

1,2-hexanediol 0.5% by mass
Olfine E1010 0.6% by mass
Olfine E1004 0.4% by mass
pH buffer (BES / NaOH aqueous solution) 2.5% by mass
Pure water 56.6% by mass

  After mixing the above components, the mixture was filtered with a 5 μm filter to obtain cyan ink 2. The ink pH was 8.4. The same evaluation as in Example 1 was performed by replacing the cyan ink 5 in place of the cyan ink 1 in Example 1. The evaluation result of image unevenness was ◯, and the ink storage stability evaluation was 15% as compared with that before storage. The change rate of other characteristics was Δ.

<Example 6>
Instead of the ink of Example 1, the pH buffering agent was changed to Bicine-sodium hydroxide and the ink adjusted to pH = 8.5 was used for the same evaluation as in Example 1. The result of image unevenness was ◯, and the change rates were all <10% and ◯.

<Example 7>
Instead of the ink of Example 1, the pH buffer was changed to ADA-sodium hydroxide and the ink adjusted to pH = 6.5 was used for the same evaluation as in Example 1. The result of image unevenness was ◯, and the change rates were all <10% and ◯.

<Example 8>
[Cyan ink 6]
Coloring material (pigment) Pigment Blue 15: 4 4% by mass
Styrene-methacrylic acid ester-methacrylic acid sodium salt copolymer (pigment dispersant)
0.4% by mass
Near-infrared absorbing aqueous dispersion (content of specific compound of structure (A) 0.24% by mass, resin dispersant PA-15 (weight average molecular weight: 17000, acid value: 11 mgKOH / g) 4.8% by mass) 21% by mass
Propylene glycol 10% by mass
Diethylene glycol monobutyl ether 3% by mass
1,2-hexanediol 0.7% by mass
Olfine E1010 0.5% by mass
Olfine E1004 0.5% by mass
pH buffer (BES / NaOH aqueous solution) 2% by mass
Pure water 57.6% by mass

After mixing the above components, the mixture was filtered with a 5 μm filter to obtain cyan ink 6.
The ink pH was 7.5. The same evaluation as in Example 1 was performed by replacing the cyan ink 6 in place of the cyan ink 1 in Example 1. The evaluation results of image unevenness were ○, and the ink storage stability evaluations were all ○.

<Example 9>
[Cyan ink 6]
Coloring material (pigment) Pigment Blue 15: 4 4% by mass
Styrene-methacrylic acid ester-methacrylic acid sodium salt copolymer (pigment dispersant)
0.4% by mass
Specific compound (specific compound of the above structure (A)) 0.01% by mass
Propylene glycol 10% by mass
Diethylene glycol monobutyl ether 3% by mass
1,2-hexanediol 0.7% by mass
Olfine E1010 2.0% by mass
Olfine E1004 1.5% by mass
pH buffer (BES / NaOH aqueous solution) 2% by mass
Pure water 76.39% by mass

After mixing the above components, the mixture was filtered with a 5 μm filter to obtain cyan ink 7.
The ink pH was 7.6. The same evaluation as in Example 1 was performed by replacing the cyan ink 7 in place of the cyan ink 1 in Example 1. The evaluation result of image unevenness was Δ, the ink storage stability evaluation was 18% for the spectral spectrum change rate, and the other characteristics were Δ for the change rate <10%.

  As described above, with the ink of the example, the storage stability of the ink containing the specific compound and the ink jet recording were compared with the ink of the comparative example whose ink pH was outside the range of 6.5 or more and 8.5 or less. The reduction in image quality is compatible.

  1, 3, 5 Inkjet recording apparatus, 10 conveying means, 12 belt, 14a, 14b roller, 20a, 20b, 20c, 20d Inkjet recording head, 22a, 22b, 22c, 22d Ink tank, 24a, 24b, 24c, 24d Tube Road, 30, 30a, 30b, 30c, 30d Laser irradiation means, 32 Laser control unit, 40 Heating device.

Claims (10)

Water, a water-soluble organic solvent, a coloring material, and a specific compound having a structure represented by the following general formula (I),
An aqueous inkjet recording ink, wherein the ink pH is in the range of 6.5 to 8.5.

(In the general formula (I), R ^a , R ^b , R ^c and R ^d each independently represents a structure represented by the general formula (IR) or an unbranched alkyl having 1 to 6 carbon atoms. R ¹ represents a hydrogen atom or a methyl group, n represents an integer of 0 or more and 3 or less, and the total carbon number of the structure represented by the general formula (IR) is 6 or less.   The aqueous inkjet recording ink according to claim 1, further comprising a resin dispersant, wherein the specific compound is dispersed in the ink. The resin dispersant is a vinyl polymer including a structural unit represented by the following general formula (II) and a structural unit derived from an alkyl (meth) acrylate, and having an acid value of 6 mgKOH / g or more and 100 mgKOH / g or less. The water-based ink jet recording ink according to claim 2, wherein:

(In General Formula (II), R ² represents a hydrogen atom, a methyl group, or —X—R ³ —A ¹ , R ⁴ represents a hydrogen atom, or —X—R ³ —A ¹ , Represents —C (═O) —, —C (═O) O—, —C (═O) NH—, —OC (═O) —, phenylene, a heterocyclic divalent group, or a single bond. , R ³ represents a divalent linking group or a single bond, and A ₁ represents —SO ₃ H, —COOH or —OPO ₃ H _{2. In the} repeating unit represented by formula (II), the same When two or more -X-R ³ -A ¹ are present as a unit, X, R ³ or A ¹ may be the same or different from each other, and a plurality of units having different structures are present in the same molecule. You may do it.)   The water-based inkjet recording ink according to claim 2, wherein the resin dispersant is polyester.   Water, a water-soluble organic solvent, a black ink containing carbon black as a color material, and the water-based inkjet recording ink according to any one of claims 1 to 4, wherein the color material is a chromatic color material An ink set for water-based inkjet recording, comprising one or more color inks.   The center wavelength is 750 nm or more after the water-based inkjet recording ink according to any one of claims 1 to 4 or the water-based inkjet recording ink set according to claim 5 is ejected from a recording head and applied to a recording medium. An ink jet recording method comprising recording by irradiating a near infrared laser in a range of 950 nm or less and drying the ink.   The recording is performed by repeatedly performing irradiation with a near-infrared laser having a center wavelength in the range of 750 nm or more and 950 nm or less after applying the ink to the recording medium for each color ink. Inkjet recording method.   After applying the ink to the recording medium for each color ink, after repeatedly applying the near-infrared laser whose center wavelength is in the range of 750 nm to 950 nm, and finally applying the ink to be recorded to the recording medium The ink jet recording method according to claim 6, wherein the ink is dried by heating the recording medium without irradiating the near infrared laser.   The inkjet recording method according to claim 6, wherein after the inks of all colors are applied to the recording medium, a near-infrared laser having a center wavelength in the range of 750 nm to 950 nm is irradiated. A recording head that discharges the water-based inkjet recording ink according to any one of claims 1 to 4 or the water-based inkjet recording ink set according to claim 5 to apply ink to a recording medium;
A near-infrared laser emitting device that irradiates the ink applied to the recording medium with a near-infrared laser having a center wavelength in the range of 750 nm to 950 nm;
An ink jet recording apparatus comprising:

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