Aqueous Ink for Inkjet Recording and Ink Cartridge

Abstract

To provide a water-based ink for ink-jet recording which, without the need for increasing the colorant concentration, can improve the optical density (OD value) of prints formed with the water-based ink.SOLUTION: This water-based ink for ink-jet recording comprises a pigment, water, and an acidic antiseptic. The pigment is, for example, a self-dispersing pigment. The acidic antiseptic includes, for example, at least one of polyvalent unsaturated fatty acids, salts of polyvalent unsaturated fatty acids, dehydroacetic acid, and salts of dehydroacetic acid.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an aqueous ink for inkjet recording and an ink cartridge.

Background Art

[0002] As a method for improving the optical density (OD value) of a recorded matter by an aqueous ink, a method of increasing the colorant concentration is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when the colorant concentration is increased, there are problems of increased cost and decreased stability of the aqueous ink.

[0005] Therefore, an object of the present invention is to provide an aqueous ink for inkjet recording that can improve the optical density (OD value) of a recorded matter by an aqueous ink without increasing the colorant concentration.

Means for Solving the Problems

[0006] To achieve the above object, the aqueous ink for inkjet recording of the present invention is characterized by containing a pigment, water, and an acidic preservative.

Effects of the Invention

[0007] The aqueous ink for inkjet recording of the present invention can improve the optical density (OD value) of a recorded matter by an aqueous ink without increasing the colorant concentration by blending the acidic preservative, and further, can impart antiseptic properties.

Brief Description of the Drawings

[0008]

Figure 1

Embodiments for Carrying Out the Invention

[0009] The water-based ink for inkjet recording of the present invention (hereinafter sometimes referred to as "water-based ink" or "ink") will be described. The water-based ink of the present invention contains a pigment, water, and an acidic preservative.

[0010] The pigment is not particularly limited, and examples thereof include carbon black, inorganic pigments, and organic pigments. Examples of the carbon black include furnace black, lamp black, acetylene black, and channel black. Examples of the inorganic pigments include titanium oxide, iron oxide-based inorganic pigments, and carbon black-based inorganic pigments. Examples of the organic pigments include azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments; polycyclic pigments such as phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments; dye lake pigments such as basic dye type lake pigments and acid dye type lake pigments; nitro pigments; nitroso pigments; aniline black daylight fluorescent pigments; etc. In addition, other pigments that can be dispersed in the aqueous phase can also be used. Specific examples of these pigments include, for example, C.I. Pigment Black 1, 6, and 7; C.I. Pigment Yellow 1, 2, 3, 12, 13, 14, 15, 16, 17, 55, 78, 150, 151, 154, 180, 185, and 194; C.I. Pigment Orange 31 and 43; C.I. Pigment Red 2, 3, 5, 6, 7, 12, 15, 16, 48, 48:1, 53:1, 57, 57:1, 112, 122, 123, 139, 144, 146, 149, 166, 168, 175, 176, 177, 178, 184, 185, 190, 202, 221, 222, 224, and 238; C.I. Pigment Violet 196; C.I. Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 16, 22, and 60; C.I. Pigment Green 7 and 36, etc.

[0011] The pigment may be a self-dispersing pigment. The self-dispersing pigment is, for example, a pigment particle in which at least one of hydrophilic functional groups such as a carbonyl group, a hydroxyl group, a carboxylic acid group, a sulfonic acid group, a phosphoric acid group and salts thereof is introduced by chemical bonding directly or via another group, and is dispersible in water without using a dispersant. As the self-dispersing pigment, for example, those obtained by treating pigments by the methods described in JP-A-8-3498, JP-T-2000-513396, JP-T-2008-524400, JP-T-2009-515007, JP-T-2011-515535 and the like can be used. As the raw material of the self-dispersing pigment, either an inorganic pigment or an organic pigment can be used. Further, examples of the pigment suitable for carrying out the treatment include carbon blacks such as "MA8" and "MA100" manufactured by Mitsubishi Chemical Corporation. The self-dispersing pigment may be, for example, a commercially available product. Examples of the commercially available product include "CAB-O-JET (registered trademark) 200", "CAB-O-JET (registered trademark) 250C", "CAB-O-JET (registered trademark) 260M", "CAB-O-JET (registered trademark) 270Y", "CAB-O-JET (registered trademark) 300", "CAB-O-JET (registered trademark) 400", "CAB-O-JET (registered trademark) 450C", "CAB-O-JET (registered trademark) 465M" and "CAB-O-JET (registered trademark) 470Y" manufactured by Cabot Specialty Chemicals; "BONJET (registered trademark) BLACK CW-2" and "BONJET (registered trademark) BLACK CW-3" manufactured by Orient Chemical Industries, Ltd.; "LIOJET (registered trademark) WD BLACK 002C" manufactured by Toyo Ink Manufacturing Co., Ltd.; and the like.

[0012] The solid content blending amount (pigment solid content amount) of the pigment with respect to the total amount of the aqueous ink is not particularly limited, and can be appropriately determined, for example, according to a desired optical density or the like. The pigment solid content amount is, for example, 0.1% by weight to 20% by weight, preferably 1% by weight to 10% by weight, and more preferably 2% by weight to 8% by weight.

[0013] The pigment may be used alone or in combination of two or more kinds.

[0014] The water is preferably ion-exchanged water or pure water. The blending amount (water ratio) of the water with respect to the total amount of the aqueous ink is appropriately determined according to desired ink properties and the like. The water ratio may be, for example, the balance of the other components.

[0015] As described above, the aqueous ink of the present invention further contains an acidic preservative.

[0016] The acidic preservative preferably contains at least one of polyunsaturated fatty acids, polyunsaturated fatty acid salts, dehydroacetic acid, and dehydroacetate salts. The polyunsaturated fatty acid is preferably sorbic acid, and the polyunsaturated fatty acid salt is preferably sorbate. Further, the sorbate preferably contains at least one of potassium sorbate and sodium sorbate. Furthermore, the dehydroacetate salt is preferably sodium dehydroacetate.

[0017] In addition to or instead of at least one of polyunsaturated fatty acids, polyunsaturated fatty acid salts, dehydroacetic acid, and dehydroacetate salts, the acidic preservative may contain other preservatives (hereinafter referred to as "other preservatives"). Examples of the other preservatives include salicylic acid, benzoic acid, and benzoate.

[0018] The acidic preservative may be used alone or in combination of two or more kinds.

[0019] The blending amount of the acidic preservative with respect to the total amount of the aqueous ink is not particularly limited, and is, for example, 0.1% by weight to 10% by weight, preferably 0.3% by weight to 6% by weight, and more preferably 0.5% by weight to 5.0% by weight.

[0020] As described above, the aqueous ink of the present invention can improve the optical density (OD value) of a recording material formed by the aqueous ink without increasing the coloring agent concentration by blending the acidic preservative, and can further impart antiseptic properties. The mechanism by which the optical density (OD value) is improved by blending the acidic preservative is presumed as follows, for example. First, since polyvalent unsaturated fatty acid salts and dehydroacetate salts are easily soluble in water, they are considered to exist as unsaturated fatty acid anions and metal cations, and dehydroacetate anions and metal cations in the ink solution. The metal cation is presumed to form a salt with the hydrophilic group on the pigment surface, aggregate the pigment, and as a result, improve the optical density (OD value). In addition, since the unsaturated fatty acid anion has an unsaturated bond, it is likely to remain on the surface of the recording medium together with the pigment, and as a result, the optical density (OD value) is presumed to be improved. However, the above mechanism is only a presumption, and the present invention is not limited thereto.

[0021] The aqueous ink of the present invention can impart antiseptic properties without using an industrial preservative, and thus can be safely used, for example, without adversely affecting the environment and human health.

[0022] The aqueous ink may further contain a surfactant. Examples of the surfactant include acetylene-based surfactants.

[0023] As the acetylene-based surfactant, for example, commercially available products may be used. Examples of the commercially available products include "Olfin (registered trademark) E1004", "Olfin (registered trademark) E1008", and "Olfin (registered trademark) E1010" manufactured by Nissin Chemical Industry Co., Ltd.; "Surfynol (registered trademark) 440", "Surfynol (registered trademark) 465", and "Surfynol (registered trademark) 485" manufactured by Air Products and Chemicals, Inc.; "Acetylenol (registered trademark) E40" and "Acetylenol (registered trademark) E100" manufactured by Kawaken Fine Chemicals Co., Ltd.; and the like.

[0024] In addition to or instead of the acetylene-based surfactant, the aqueous ink may contain other surfactants. Examples of the other surfactants include nonionic surfactants of the "EMULGEN (registered trademark)" series, "RHEODOL (registered trademark)" series, "EMASOL (registered trademark)" series, "EXCEL (registered trademark)" series, "EMANON (registered trademark)" series, "AMIET (registered trademark)" series, and "AMINON (registered trademark)" series manufactured by Kao Corporation; nonionic surfactants of the "SOLBON (registered trademark)" series manufactured by Toho Chemical Industry Co., Ltd.; nonionic surfactants of the "DOBANOX (registered trademark)" series, "LEOCOL (registered trademark)" series, "LEOX (registered trademark)" series, "LAOL, LEOCOL (registered trademark)" series, "LIONOL (registered trademark)" series, "CADENAX (registered trademark)" series, "LIONON (registered trademark)" series, and "LEOFAT (registered trademark)" series manufactured by Lion Corporation; anionic surfactants of the "EMAL (registered trademark)" series, "LATEMUL (registered trademark)" series, "VENOL (registered trademark)" series, "NEOPELEX (registered trademark)" series, NS SOAP, KS SOAP, OS SOAP, and "PELEX (registered trademark)" series manufactured by Kao Corporation; anionic surfactants of the "LIPOLAN (registered trademark)" series, "LIPON (registered trademark)" series, "SUNNOL (registered trademark)" series, "LIPOTAC (registered trademark) TE, ENAGICOL" series, "LIPAL (registered trademark)" series, and "LOTAT (registered trademark)" series manufactured by Lion Corporation; cationic surfactants of the "CATION GEN (registered trademark) ES-OW" and "CATION GEN (registered trademark) ES-L" manufactured by Daiichi Kogyo Seiyaku Co., Ltd. The surfactants may be used alone or in combination of two or more.

[0025] The compounding amount of the surfactant is, for example, 0.01% by weight to 5% by weight, preferably 0.05% by weight to 5% by weight, more preferably 0.05% by weight to 3% by weight. In particular, the compounding amount of the acetylene-based surfactant with respect to the total amount of the aqueous ink is, for example, 0.01% by weight to 5% by weight, preferably 0.05% by weight to 3% by weight.

[0026] It is preferable that the compounding amounts of the acidic preservative and the surfactant with respect to the total amount of the aqueous ink satisfy, for example, the following condition (X). From the viewpoints of OD value and color saturation improvement, the lower limit of the following condition (X) is preferably 0.5 or more. Also, from the viewpoint of the ejection stability of the ink, the following condition (X) is preferably 50 or less. Condition (X): 0.5 ≤ A / B ≤ 50 A: The compounding amount (weight %) of the acidic preservative B: The compounding amount (weight %) of the surfactant

[0027] The aqueous ink preferably further contains a water-soluble organic solvent. Examples of the water-soluble organic solvent include a wetting agent that prevents the drying of the aqueous ink at the nozzle tip of the inkjet head and a penetrant that adjusts the drying rate on the recording medium.

[0028] The wetting agent is not particularly limited. For example, lower alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol; amides such as dimethylformamide, dimethylacetamide; ketones such as acetone; keto alcohols such as diacetone alcohol; ethers such as tetrahydrofuran, dioxane; polyethers such as polyalkylene glycol; polyhydric alcohols such as alkylene glycol, glycerin, trimethylolpropane, trimethylolethane; 2-pyrrolidone; N-methyl-2-pyrrolidone; 1,3-dimethyl-2-imidazolidinone and the like can be mentioned. Examples of the polyalkylene glycol include polyethylene glycol, polypropylene glycol and the like. Examples of the alkylene glycol include ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, thiodiglycol, hexylene glycol and the like. These wetting agents may be used alone or in combination of two or more. Among these, polyhydric alcohols such as alkylene glycol and glycerin are preferred.

[0029] The compounding amount of the wetting agent with respect to the total amount of the aqueous ink is, for example, 0% by weight to 95% by weight, preferably 5% by weight to 80% by weight, and more preferably 5% by weight to 50% by weight.

[0030] The penetration agent preferably contains at least one of an alkylene diol and a glycol ether compound. Examples of the alkylene diol include 1,2 - hexanediol, 1,2 - heptanediol, 1,3 - propanediol, 1,2 - butanediol, 1,3 - butanediol, 1,4 - butanediol, 2,3 - butanediol, 3 - methyl - 1,3 - butanediol, 1,3 - propanediol, 1,2 - butanediol, 1,2 - pentanediol, 1,4 - butanediol, 1,5 - pentanediol, 1,6 - hexanediol, 2 - methyl - 2,4 - pentanediol, and 3 - methyl - 1,5 - pentanediol. Examples of the glycol ether compound include ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol - n - propyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol - n - propyl ether, diethylene glycol - n - butyl ether, diethylene glycol - n - hexyl ether, triethylene glycol methyl ether, triethylene glycol ethyl ether, triethylene glycol - n - propyl ether, triethylene glycol - n - butyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol - n - propyl ether, propylene glycol - n - butyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol - n - propyl ether, dipropylene glycol - n - butyl ether, tripropylene glycol methyl ether, tripropylene glycol ethyl ether, tripropylene glycol - n - propyl ether, and tripropylene glycol - n - butyl ether. The penetration agent may be used alone or in combination of two or more kinds.

[0031] The blending amount of the penetrant with respect to the total amount of the aqueous ink is, for example, 1% by weight to 20% by weight, preferably 1% by weight to 15% by weight, and more preferably 1% by weight to 10% by weight. In particular, the blending amount of at least one of the alkylene diol and the glycol ether compound with respect to the total amount of the aqueous ink is, for example, 1% by weight to 20% by weight, preferably 1% by weight to 15% by weight, and more preferably 1% by weight to 10% by weight.

[0032] The blending amounts of the acidic preservative and the penetrant with respect to the total amount of the aqueous ink preferably satisfy the following condition (Y), for example. From the viewpoints of OD value and color density improvement, the lower limit of the following condition (Y) is preferably 0.1 or more. Also, from the viewpoint of ink ejection stability, the following condition (Y) is preferably 5 or less. Condition (Y): 0.1 ≤ A / C ≤ 5 A: Blending amount (weight %) of the acidic preservative C: Blending amount (weight %) of the penetrant

[0033] The aqueous ink may further contain a conventionally known additive as needed. Examples of the additive include a pH adjuster, a viscosity adjuster, a surface tension adjuster, a fungicide, and the like. Examples of the viscosity adjuster include polyvinyl alcohol, cellulose, water-soluble resins, and the like.

[0034] Next, an ink cartridge of the present invention is an ink cartridge containing an aqueous ink for inkjet recording, characterized in that the aqueous ink is the aqueous ink for inkjet recording of the present invention. As the main body of the ink cartridge, for example, a conventionally known one can be used.

[0035] Next, an inkjet recording apparatus and an inkjet recording method of the present invention will be described.

[0036] The inkjet recording apparatus of the present invention includes an ink storage unit and an ink ejection means, and is an inkjet recording apparatus that ejects the ink stored in the ink storage unit by the ink ejection means, wherein the ink storage unit stores the aqueous ink for inkjet recording of the present invention.

[0037] The inkjet recording method of the present invention is an inkjet recording method in which an aqueous ink is ejected onto a recording medium by an inkjet method for recording, and the aqueous ink for inkjet recording of the present invention is used as the aqueous ink.

[0038] The inkjet recording method of the present invention can be implemented using, for example, the inkjet recording apparatus of the present invention. The recording includes printing, printing pictures, printing, etc.

[0039] FIG. 1 shows the configuration of an example of the inkjet recording apparatus of the present invention. As shown in the figure, this inkjet recording apparatus 1 includes four ink cartridges 2, an ink ejection means (inkjet head) 3, a head unit 4, a carriage 5, a drive unit 6, a platen roller 7, and a purge device 8 as main components.

[0040] The four ink cartridges 2 each contain one of the four colors of aqueous ink: yellow, magenta, cyan, and black. At least one of the four colors of aqueous ink is the aqueous ink for inkjet recording of the present invention. The inkjet head 3 installed in the head unit 4 performs recording on a recording medium (for example, recording paper) P. The four ink cartridges 2 and the head unit 4 are mounted on the carriage 5. The drive unit 6 reciprocates the carriage 5 in a linear direction. As the drive unit 6, for example, a conventionally known one can be used (see, for example, Japanese Patent Application Laid-Open No. 2008-246821). The platen roller 7 extends in the reciprocating direction of the carriage 5 and is disposed opposite to the inkjet head 3.

[0041] The purge device 8 sucks the defective ink containing bubbles or the like accumulated inside the inkjet head 3. As the purge device 8, for example, a conventionally well-known one can be used (for example, refer to Japanese Patent Application Laid-Open No. 2008-246821).

[0042] On the side of the platen roller 7 of the purge device 8, a wiper member 20 is disposed adjacent to the purge device 8. The wiper member 20 is formed in a spatula shape and wipes the nozzle forming surface of the inkjet head 3 as the carriage 5 moves. In FIG. 1, the cap 18 covers a plurality of nozzles of the inkjet head 3 that is returned to the reset position when the recording is completed in order to prevent the drying of the aqueous ink.

[0043] In the inkjet recording apparatus 1 of this example, the four ink cartridges 2 are mounted on one carriage 5 together with the head unit 4. However, the present invention is not limited to this. In the inkjet recording apparatus 1, each of the four ink cartridges 2 may be mounted on a carriage different from the head unit 4. Further, each of the four ink cartridges 2 may not be mounted on the carriage 5 and may be arranged and fixed in the inkjet recording apparatus 1. In these aspects, for example, each of the four ink cartridges 2 and the head unit 4 mounted on the carriage 5 are connected by a tube or the like, and the aqueous ink is supplied from each of the four ink cartridges 2 to the head unit 4.

[0044] The inkjet recording using this inkjet recording apparatus 1 is carried out, for example, as follows. First, the recording paper P is fed from a paper feed cassette (not shown) provided on the side or below the inkjet recording apparatus 1. The recording paper P is introduced between the inkjet head 3 and the platen roller 7. A predetermined recording is made on the introduced recording paper P with aqueous ink ejected from the inkjet head 3. The recording paper P after recording is discharged from the inkjet recording apparatus 1. The recording made with the aqueous ink of the present invention has a high optical density (OD value). In FIG. 1, the illustration of the paper feed mechanism and the paper discharge mechanism of the recording paper P is omitted.

[0045] In the apparatus shown in FIG. 1, a serial type inkjet head is employed, but the present invention is not limited thereto. The inkjet recording apparatus may be an apparatus employing a line type inkjet head.

Example

[0046] Next, the examples of the present invention will be described together with comparative examples. Note that the present invention is not limited or restricted by the following examples and comparative examples.

[0047] [Examples 1 to 28 and Comparative Examples 1 to 4] In the aqueous ink compositions (Tables 1 to 3), the components excluding the pigment were uniformly mixed to obtain an ink solvent. Next, the ink solvent was added to the pigment dispersed in water and uniformly mixed. Then, the obtained mixture was filtered through a cellulose acetate type membrane filter (pore diameter: 3.00 μm) manufactured by Toyo Roshi Kaisha, Ltd. to obtain aqueous inks for inkjet recording of Examples 1 to 28 and Comparative Examples 1 to 4. As shown in Table 1, in Examples 1 to 15, either potassium sorbate or sodium sorbate was used as the acidic preservative. Also, as shown in Table 2, in Examples 16 to 28, sodium dehydroacetate was used as the acidic preservative.

[0048] Regarding the aqueous inks of Examples 1 to 28 and Comparative Examples 1 to 4, (a) recording density evaluation and (b) antiseptic property evaluation were carried out by the following methods.

[0049] (a) Recording density evaluation The aqueous inks of Examples 1 to 28 and Comparative Examples 1 to 4 were applied to a recording medium ("Multi Paper Super White +" manufactured by Asukuru Co., Ltd.) so that the coating amount per unit area was about 0.90 mg / cm 2 to prepare evaluation samples. The optical density (OD value) at five positions in the evaluation samples was measured with a SpectroEye spectrophotometer (light source: D50, viewing angle: 2°, ANSI-T) manufactured by X-Rite, and the average value was obtained. Next, from the optical density (OD value) in Examples 1 to 14, Examples 16 to 27, Comparative Example 2, and Comparative Example 3, the optical density (OD value) in Comparative Example 1 in which the evaluation samples were prepared only with an aqueous black pigment ink (CAB-O-JET® 300) without using an acidic preservative was subtracted to calculate the optical density (OD value) difference (ΔOD). Similarly, from the optical density (OD value) in Example 15 and Example 28, the optical density (OD value) in Comparative Example 4 in which the evaluation samples were prepared only with an aqueous magenta pigment ink (CAB-O-JET® CAB-O-JET465) without using an acidic preservative was subtracted to calculate the optical density (OD value) difference (ΔOD). Then, the recording density was evaluated according to the following evaluation criteria.

[0050] Recording concentration evaluation criteria AA: The improvement in optical density (OD value) (ΔOD) was 0.1 or more. A: The improvement in optical density (OD value) (ΔOD) was 0.06 or more and 0.09 or less. B: The improvement in optical density (OD value) (ΔOD) was 0.03 or more and 0.05 or less. C: The improvement in optical density (OD value) (ΔOD) was 0.02 or less.

[0051] (b) Antiseptic property evaluation The aqueous inks of Examples 1 to 28 and Comparative Examples 1 to 4 were applied to a standard agar medium and stored for 3 days in an environment at a temperature of 35°C. Then, it was visually confirmed whether mold colonies had occurred on the standard agar, and the antiseptic property was evaluated according to the following evaluation criteria.

[0052] Anticorrosion evaluation criteria A: No colony formation C: Colony formation occurred

[0053] The aqueous ink compositions and evaluation results of the aqueous inks of Examples 1 to 28 and Comparative Examples 1 to 4 are shown in Tables 1 to 3.

[0054]

Table 1

[0055]

Table 2

[0056]

Table 3

[0057] As shown in Tables 1 and 2, in Examples 1 to 28, an improvement in the recording density (OD value) was observed, and all the results of the antiseptic property evaluation were good. In particular, in Examples 1, 2, 6, 7, 9, 10, 12 to 14, and 19, the degree of improvement in the recording density (OD value) was large.

[0058] On the other hand, as shown in Table 3, in Comparative Examples 1 and 4 where no preservative was used, the results of the antiseptic property evaluation were poor. Also, in Comparative Example 2 where 1,2-dibenzisothiazolin-3-one (trade name: PROXEL GXL of Arch Chemicals) was used instead of the acidic preservative, the recording density (OD value) was equivalent to that of Comparative Example 1. Further, in Comparative Example 3 where sodium ascorbate was used instead of the acidic preservative, the results of the antiseptic property evaluation were poor.

Industrial Applicability

[0059] As described above, the aqueous ink of the present invention can improve the optical density (OD value) of a recording made with the aqueous ink without increasing the colorant concentration, and furthermore, has imparted antiseptic properties. The use of the aqueous ink of the present invention is not particularly limited, and it can be widely applied to various inkjet recordings.

Explanation of Signs

[0060] 1 Inkjet recording apparatus 2 Ink cartridge 3 Ink ejection means (inkjet head) 4 Head unit 5 Carriage 6 Drive unit 7 Platen roller 8 Purge device

Claims

1. An inkjet recording aqueous ink comprising a pigment, water, an acidic preservative, and a penetrant, wherein the acidic preservative includes at least one of polyunsaturated fatty acids, polyunsaturated fatty acid salts, dehydroacetic acid, and dehydroacetic acid salts, the penetrant includes at least one of alkylene diol compounds and glycol ether compounds, the content of the acidic preservative is 0.5% by mass or more and 5.0% by mass or less, and the blending amounts of the acidic preservative and the penetrant satisfy the following condition (Y). An inkjet recording aqueous ink characterized by this. Condition (Y): 0.1 ≦ A / C ≦ 5 A: Blending amount (weight %) of the acidic preservative C: Blending amount (weight %) of the penetrant

2. The inkjet recording aqueous ink according to claim 1, wherein the pigment is a self-dispersing pigment.

3. The inkjet recording aqueous ink according to claim 1 or 2, wherein the polyunsaturated fatty acid is sorbic acid, and the polyunsaturated fatty acid salt is a sorbate.

4. The inkjet recording aqueous ink according to claim 3, wherein the sorbate includes at least one of potassium sorbate and sodium sorbate.

5. The inkjet recording aqueous ink according to any one of claims 1 to 4, wherein the dehydroacetic acid salt is sodium dehydroacetate.

6. The inkjet recording aqueous ink according to any one of claims 1 to 5, further comprising a surfactant.

7. The inkjet recording aqueous ink according to claim 6, wherein the surfactant is an acetylene-based surfactant.

8. The inkjet recording aqueous ink according to any one of claims 1 to 7, wherein at least one of the alkylene diol and the glycol ether compound is at least one selected from the group consisting of 1,2-hexanediol, 3-methyl-1,5-pentanediol, and triethylene glycol-n-butyl ether (BTG).

9. The inkjet recording aqueous ink according to any one of claims 6 to 8, wherein the blending amounts of the acidic preservative and the surfactant satisfy the following condition (X). Condition (X): 0.5 ≦ A / B ≦ 50 A: Blending amount (weight %) of the acidic preservative B: Blending amount (weight %) of the surfactant

10. An ink cartridge containing an aqueous ink for inkjet recording, wherein the aqueous ink is the aqueous ink for inkjet recording according to any one of claims 1 to 9.

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