JP2003020426A - Ink for ink-jet recording and recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ink for ink-jet recording with which an image having high water resistance and light resistance, high density and slight bleeding can be provided and which has high reliability and excellent discharge stability. SOLUTION: This ink for ink-jet recording is characterized by an ink comprising water, a colorant dispersible and/or soluble in water, a surfactant, a wetting agent and 2-ethyl-1,3-hexanediol (hereinafter abbreviated to EHD), the EHD contains 0.05-1 wt.% of a butyric acid ester compound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording ink, which is capable of providing an image having high water resistance and light resistance, high density and little bleeding, and having high reliability and excellent ejection stability. Regarding the device.

[0002]

2. Description of the Related Art Ink jet recording methods are capable of high-speed recording, and various recording media such as plain paper can be used because they are non-contact with the recording medium.
Due to the advantage of being able to obtain a color image at a low cost, there has been a remarkable spread in recent years. Ink jet recording requires that the ink used satisfy the following conditions in order to perform good print recording for a long period of time.

1. Excellent ejection characteristics such as ink ejection direction stability and ejection stability. 2. The storage stability of the ink is excellent. That is, during long-term storage, continuous use, or during recording pauses, precipitation may occur due to chemical changes, resulting in nozzle clogging or changes in ink physical properties. 3. The contrast of the printed image is high enough,
It must be a clear image without bleeding. 4. The recorded image should dry quickly. 5. The printed and recorded image has excellent water resistance, light resistance, etc., that is, storage stability.

In order to satisfy the above requirements, many proposals have hitherto been made as inks used for ink jet recording and the like, but inks sufficiently satisfying all the above conditions have not yet been obtained. is the current situation.

In the case of a color printer, in particular, if the drying speed of the ink is slow, high image quality can be ensured in the monochromatic printing portion, but image quality such as bleeding may occur in the secondary color portion. In the case of performing the drying without using it, bleeding and the like at the color boundary often occurred remarkably.

Considering that the printing speed will further increase in the future and that the image quality of the color boundary and the two-color overlapping portion of the color image will be improved, it is an important task to accelerate the drying of the ink. It is no exaggeration to say that the choice of penetrant that controls the ink permeability affects image quality.

Surfactants lower the surface tension of the ink,
Although it is added for the purpose of enhancing the penetrability into paper, for example, in the formulation described in JP-A-55-29546, although the apparent dryness is improved, this formulation has a drawback that it remarkably bleeds on the paper. Further, Japanese Patent Publication No. 58-6752 discloses a quick-drying ink having improved penetrability and less bleeding by using an ethylene oxide adduct pair having an acetylene bond as a surfactant. Has a problem that the drying speed is not improved due to the interaction depending on the dyes used at the same time. Further, according to JP-B-60-23793, dialkylsulfosuccinic acid as a surfactant is said to improve the drying property and reduce the image quality deterioration, but it is known that sodium dioctylsulfosuccinate and di (2 −
Ethylhexyl) sodium sulfosuccinate or the like has a problem that the pixel diameter is significantly different depending on the paper. Further, in JP-A-6-157959, 2-ethyl-1,3
Although it is said that it is preferable to add hexanediol (EHD), the solubility of EHD alone was poor, and the balance between the ink drying property and the image quality was insufficient. In addition, E
Depending on the degree of refining of HD, there may be a problem in storage stability, liable to cause clogging, and odor due to impurities may become a problem.

Further, in recent years, in order to improve the water resistance and light resistance of an image, a pigment such as carbon black has come to be used in place of the conventionally used dye.

In this type of pigment ink composition, various brands of carbon black commercially available for colorants (for color) are used. Of these, acidic carbon black has a relatively good affinity for water as compared with neutral or basic ones, and is used in aqueous pigment ink compositions and the like. Acidic carbon black is believed to have acidic groups such as carboxyl groups on its surface. These are generally gas phase or liquid phase oxidation methods using conventional oxidants such as ozone, nitric acid, hydrogen peroxide, and nitrogen oxides, or surface modification methods such as plasma treatment, such as furnace black. It is obtained by appropriately oxidizing carbon black for color.

However, although such a conventional acidic carbon black or channel black exhibits hydrophilicity to some extent, it has insufficient affinity for an aqueous medium and dispersion stability, and is difficult to disperse in water by itself. Therefore, when these are used as a colorant for an aqueous pigment ink composition, they are dispersed in an aqueous medium using a disperser in the presence of a so-called pigment dispersant such as various water-soluble synthetic polymers and surfactants. It needs to be dispersed and stabilized.

For example, JP-A-64-6074 and JP-A-4-149286 disclose an aqueous pigment ink composition containing acidic carbon black, a dispersant (anionic surfactant or polymer dispersant), and a buffer solution. Things are listed. Further, in Japanese Patent Laid-Open No. 3-210373, the volatile content is 3.
An inkjet ink composition is described that contains 5 to 8 wt% acidic carbon black and a water-soluble resin.
Further, JP-A-3-134073 describes an inkjet recording liquid containing neutral or basic carbon black and a water-soluble resin.

However, when using commercially available carbon black as in the conventional aqueous pigment ink composition, the resin forming the dispersant is not redissolved or redistributed after adhering to the orifice etc. Non-ejection of droplets easily occurs. In addition, since the aqueous pigment ink composition containing the dispersant is viscous, when performing continuous ejection and high-speed printing for a long time, resistance is generated in the path to the nozzle tip, and ejection becomes unstable and high-speed smooth recording is possible. It will be difficult. In order to solve these drawbacks, Japanese Patent Application No. 8-98436 discloses an aqueous pigment ink composition containing no pigment dispersant. However, with the aqueous pigment ink composition described here, it is difficult to sufficiently increase the density of the recorded matter because the color tone of carbon black is reddish. Further, these have drawbacks such that uneven printing is more likely to occur than in the dye ink composition and light and shade are generated in printing.

The role of the wetting agent is to stably dissolve the colorant in water, thereby preventing clogging due to dye precipitation and the like due to water evaporation near the nozzle.
If the amount of wetting agent is large, the storage stability of the ink will increase, but
If the amount is too large, the viscosity becomes high and problems such as difficulty in discharging from the nozzle occur.

[0014]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide an image having high water resistance and light fastness, high density and little blurring. Another object of the present invention is to provide an inkjet recording ink having high reliability and excellent ejection stability, and a recording apparatus therefor.

More specifically, firstly, high image quality is obtained,
And to present a penetrant to improve both the reliability and safety of the ink, and second, to maintain high reliability,
Providing an appropriate amount of penetrant to obtain a clear image with high image density, and third, presenting a type of colorant having high water resistance and light resistance and high image density, and high reliability, Fourth, presenting the structure and addition amount of the surfactant for providing a clearer image, fifth, presenting the structure of the counter ion for ensuring higher reliability, sixth. To present the kind and addition amount of the wetting agent for providing the ink having higher storage stability. Seventh, all the drawbacks of the prior art are solved, and the image has high water resistance and light fastness and high density. An object of the present invention is to provide a recording apparatus equipped with an inkjet recording ink that has less bleeding, is highly reliable, and has excellent ejection stability.

[0016]

The present invention provides an ink jet recording ink having high water resistance and light fastness of an image, capable of providing an image with high density and less bleeding, and having high reliability and excellent ejection stability. The present invention relates to the recording device and has the following structure.

[1] Water, a colorant which is dispersed and / or dissolved in water, a surfactant, a wetting agent, and 2-ethyl-1,3-
In an ink containing hexanediol (hereinafter abbreviated as EHD), the EHD contains a butyrate compound in an amount of 0.05 to 1
An ink for inkjet recording, which is EHD contained in a range of wt%.

[2] The amount of EHD is 0.
[1] characterized in that it is in the range of 1 to 4% by weight.
The ink for inkjet recording described.

[3] The coloring agent is neutral or acidic carbon black, and its surface is bound with at least one functional group of a carbonyl group, a carboxyl group, a hydroxyl group, or a sulfone group or a salt thereof. The ink for inkjet recording according to the above [1] or [2], which is capable of being dispersed and / or dissolved in water without a dispersant by being surface-treated.

[4] The surfactant is represented by the following general formula (1)
Which is a surfactant represented by
5 to 3% by weight is contained, [1] to
The inkjet recording ink according to any one of [3]. _{RO (CH 2 CH 2 O)} n CH 2 COOM (1) R: a linear or branched alkyl group having a carbon number of 13 or 14 n: 3 to 12 integer M: alkali metal, quaternary ammonium, quaternary Phosphonium or alkanolamine

[5] The counter ion of the colorant and / or the counter ion of the surfactant contained in the ink is sodium,
Inkjet recording according to any one of the above [1] to [4], which is lithium and / or a quaternary ammonium represented by the following general formula (2), a quaternary phosphonium, or an alkanolamine ion. Ink.

[0022]

[Chemical 2] Z: nitrogen or phosphorus R _{1 to} R ₄ : hydrogen, an alkyl group having 1 to 4 carbon atoms, a hydroxyl group or a halogenated alkyl group

[6] The wetting agent is a mixture of glycerol and diethylene glycol and is contained in an amount of 10 to 30% by weight based on the total amount of the ink. [1] to [5] Ink for inkjet recording.

[7] An ink jet recording apparatus equipped with the ink for ink jet recording according to any one of the above [1] to [6].

The present invention will be described in detail below with reference to specific examples. The present invention relates to an inkjet recording ink containing water, a colorant that disperses and / or dissolves in water, a penetrant, a wetting agent, and a surfactant, and the content of the butyric acid ester compound is 0.05 to 1 as the penetrant. It has been found that the use of EHD in the range of wt% makes it possible to obtain a high-quality image with high safety, high image density even with high-speed printing and less bleeding. The butyric acid ester compound is a by-product when synthesizing EHD, and there is a problem that the cost required for the purification process increases in order to keep the content to less than 0.05% by weight, and when it exceeds 2% by weight. It may affect reliability and may cause odors and other problems. EHD containing a butyric acid ester within the scope of the present invention is produced by using a highly pure product from the stage of the raw material aldehyde, and the EHD produced in this manner is, for example, Specifically, it can be obtained as "octanediol" manufactured by Kyowa Hakko Co., Ltd.

In the present invention, EHD having a content of the butyric acid ester compound in the range of 0.05 to 1% by weight is added as a penetrating agent to enhance the penetrability of the ink and at the same time to add the colorant to the surface. By limiting the amount to 1, it is possible to obtain a printed image with no boundary blurring, high image density, and little show-through. The amount of EHD added is preferably 0.1 to 4% by weight of the total amount of the ink, and more preferably 0.1.
It is 5 to 3% by weight. If it is less than 0.1% by weight, the effect is small, and if it exceeds 4% by weight, the solubility itself is low, resulting in poor reliability.

Further, in the present invention, in addition to EHD, penetrants shown below may be used in combination within a range that does not affect the characteristics. For example, 2,2,4-trimethyl-
1,3-pentanediol, 1,2,4-trimethyl-
1,3-pentanediol, HOCH ₂ C (CH ₃ ) ₂ C
H ₂ OCOC (CH ₃ ) ₂ CH ₂ OH (ester diol 2
04), C ₆ H ₁₂ OCH ₂ CH ₂ OH (hexyl cellosolve), C ₆ H ₁₃ O (C ₂ H ₄ O) ₂ H (hexyl carbitol) and the like.

In the present invention, the colorant contained in the above-mentioned ink is neutral with at least one functional group of a carbonyl group, a carboxyl group, a hydroxyl group or a sulfone group or a salt thereof bonded to the surface. Alternatively, by using a carbon black which is an acidic carbon black and can be dispersed and / or dissolved in water by such a surface treatment without a dispersant, the ejection stability and the ejection response are excellent, and the nozzle is also excellent. It was found that a highly reliable water-based pigment ink that does not cause clogging and the like can be obtained.

The neutral or acidic carbon black used in the present invention may be one in which a specific functional group on the surface of carbon black is chemically bonded directly or through another atomic group, or alternatively, hypohalous acid is used. And / or a reaction product obtained by a wet oxidation treatment using a salt thereof.

Carbon black as a raw material of neutral or basic carbon black is generally carbon powder obtained by thermal decomposition or incomplete combustion of natural gas or liquid hydrocarbon (heavy oil, tar, etc.). The carbon blacks thus obtained include channel blacks, furnace blacks, lamp blacks; acidic carbon blacks, neutral carbon blacks, basic carbon blacks; CI pigment blacks 6, 7 and CI pigment blacks. 1
0; and the like are generally included.

Carbon black as a raw material used in the present invention has a primary particle diameter of 40 nm or less, preferably 30 n.
m or less, more preferably 30 to 10 nm. When the primary particle diameter exceeds 40 nm, the coloring power of the original carbon black itself is low, and the optical density (reflection density) of the recorded matter is lowered.

The ink of the present invention comprises at least water, a colorant that disperses and / or dissolves in water, a surfactant, and a wetting agent, and the colorant of the present invention is dispersed and / or dispersed in water without a dispersant. Although it can be dissolved, in the present invention, a state in which the colorant is stably present in water without a dispersant is referred to as “dispersion and / or dissolution”. There are many cases where it is difficult to clearly distinguish whether a substance is dissolved or dispersed. In the present invention, as long as it is a colorant that can stably exist in water without a dispersant, such a colorant can be used regardless of whether the state is dispersed or dissolved. Therefore, in this specification, a pigment that can stably exist in water without a dispersant is sometimes referred to as a water-soluble pigment, but it does not mean that even a pigment in a dispersed state is excluded.

The colorant preferably used in the present invention can be obtained, for example, by the method described in JP-A-8-3498. It is also possible to use a commercially available product as the colorant, and preferred examples are CAB-O-JET200 and CAB-O-JET30 manufactured by Cabot Specialty Chemicals Inc.
0, IJX-181, 157, and 164 and Microjet CW1 or 2 manufactured by Orient Chemical Industry Co., Ltd.

The amount of colorant added to the ink is preferably 2 to 15% by weight, more preferably 4 to 10% by weight.

Further, as the surfactant used in the present invention, the surfactant represented by the following general formula (1) is used, whereby the drying is fast and clear printing without boundary bleeding and character bleeding is performed. Images can now be provided.

RO (CH ₂ CH ₂ O) _n CH ₂ COOM (1) R: a linear or branched alkyl group having 13 or 14 carbon atoms n: an integer of 3 to 12 M: alkali metal, quaternary ammonium, Quaternary phosphonium or alkanolamine

Commercially available surfactants containing this compound as a main component include ECTD-3NEX (in the general formula (1)) available from Nikko Chemicals Co., Ltd.
R: tridecyl group, n: 3, M: Na), ECTD-6
NEX (in the general formula (1), R: tridecyl, m:
6, M: Na) and the like.

In the present invention, in addition to the above-mentioned surfactants, the following surfactants may be used in combination as long as they do not affect the ink characteristics. Surfactants that can be used in combination include polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene glycol ester, nonionic surfactants such as acetylene-based surfactants and silicon-based surfactants, and polyoxyethylene Examples thereof include anionic surfactants such as ethylene alkyl ether acetate and dialkyl sulfosuccinate.

Specifically, as nonionic surfactants, BT series (Nikko Chemicals), Nonipol series (Sanyo Kasei), Surfynol series (Air Products) silicone (Toray Dow Corning, etc.) are available. Further, as the anionic surfactant,
Specifically, it is available as the Nikkor ECT series (trade name, manufactured by Nippon Surfactant Chemical Co., Ltd.) and the like.

These surfactants are added in order to reduce the surface tension of the ink and increase the penetrability of the ink into the paper to accelerate the drying property of the printed image.
The surface tension of the ink is usually 50 mN /
It is adjusted to m or less, preferably 40 mN / m or less, and is preferably 0.05 to 5.0% by weight with respect to the total amount of the aqueous ink composition. The amount of the surfactant added is 0.05.
If it is less than 5% by weight, the dynamic surface tension is high and the drying property is poor. On the contrary, if it is more than 5.0% by weight, precipitation of a surfactant or the like occurs during storage.

When the counter ion of the colorant and the counter ion of the surfactant are sodium, lithium and / or quaternary ammonium, quaternary phosphonium or alkanolamine ion represented by the following general formula (2): Excellent dissolution stability and good printed image can be obtained.

[0042]

[Chemical 3] Z: nitrogen or phosphorus R _{1 to} R ₄ : hydrogen, an alkyl group having 1 to 4 carbon atoms, a hydroxyl group or a halogenated alkyl group

The counter ion can be easily changed to such an alkali ion by adding an alkali hydroxide containing a desired alkali ion when dissolving these in water during ink preparation. For example, in the case of a lithium salt, it can be performed by adding lithium hydroxide.

The wetting agent used in the present invention includes
It was revealed that the use of a mixture of diethylene glycol and glycerol markedly improves the storage stability and ejection stability of the ink.

In the present invention, in addition to the above wetting agents, the following wetting agents may be used in combination within the range that does not affect the characteristics. Wetting agents that can be used in combination include ethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, 1,6-hexanediol, 1,2,6-hexanetriol, 1,2,4-butane. Triol,
Polyhydric alcohols such as 1,2,3-butanetriol and petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol Polyhydric alcohol alkyl ales such as monoethyl ether, polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether, 2-
Pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethylimidinazolidinone, ε-caprolactam and the like nitrogen-containing heterocyclic compounds, and the like, but the present invention includes these. It is not limited.

The content of the wetting agent is 10 to 30% by weight.
However, it is more preferably 12 to 20% by weight. When the amount of the wetting agent is less than 10% by weight, the dissolution stability of the colorant is insufficient and the colorant is likely to be deposited at the nozzle portion. When the amount of the wetting agent exceeds 30%, the increase of the ink due to the environmental temperature change is increased. Stickiness becomes a problem.

In the present invention, an antiseptic / antifungal agent may be added in addition to the above additives. As a good antiseptic / antifungal agent, 1,2-benzisothiazolin-3-one can be used, whereby inks and prints having excellent antiseptic / antifungal effects while ensuring reliability such as storage stability and ejection stability are obtained. Images can be provided. The addition amount of the antiseptic / antifungal agent is preferably 0.2 to 1.0% by weight. If the addition amount is less than 0.2% by weight, the antiseptic / antifungal effect becomes insufficient, and if the addition amount exceeds 1.0% by weight, precipitation of the antiseptic / antifungal agent itself may be a problem. Examples of commercially available antiseptic and fungicides containing 1,2-benzisothiazolin-3-one include Saneyevac AP (manufactured by San-ai Petroleum Co., Ltd.) and
Proxel XL (manufactured by ICI) and the like can be mentioned.

Further, in the present invention, a penetrant, a metal corrosion inhibitor, a water-soluble ultraviolet absorber, and
A water-soluble infrared absorber or the like can be added.

[0049]

BEST MODE FOR CARRYING OUT THE INVENTION Examples and comparative examples of the present invention will be shown below. Example 1 The purity of EHD "octanediol" manufactured by Kyowa Hakko Co., Ltd.
It was analyzed by gas chromatography (manufactured by HP) and it was confirmed that the content of contained butyric acid ester was in the range of 0.05 to 1% by weight.

Using this EHD, an ink was prepared with the following composition, but no odor was noticed during the preparation of the ink. <Composition of black ink> CAB-O-JET300 (manufactured by Cabot Specialty Chemicals, Inc.) 5% by weight EHD (manufactured by Kyowa Hakko Co., Ltd.) 2% by weight diethylene glycol 15% by weight glycerol 5% by weight 2-pyrrolidone 2% by weight ECTD -3NEX (Nikko Chemicals) 1% by weight Proxel XL (manufactured by ICI) 0.4% by weight Ion-exchanged water Remaining amount

Comparative Example 1 The purity of EHD of a commercially available special grade reagent was analyzed by gas chromatography as in Example 1, and it was confirmed that the content of butyric acid ester compound was 2% by weight or more.

Using this EHD, an ink was prepared with the following composition. <Composition of Black Ink> CAB-O-JET300 (manufactured by Cabot Specialty Chemicals, Inc.) 5% by weight EHD 2% by weight Diethylene glycol 15% by weight Glycerol 5% by weight ECTD-3NEX (Nikko Chemicals) 1% by weight Proxel XL ( ICI) 0.4% by weight deionized water remaining

The ink of Example 1 and the ink of Comparative Example 1 formulated with the above composition were dissolved by stirring at room temperature, and the pH was adjusted to 10.5 with lithium hydroxide.
Each of the inks was prepared by filtering with a Teflon (registered trademark) filter of m.

Next, these inks were evaluated for reliability after being left for a long period of time, and for the presence or absence of odor during ink preparation. The results are shown in Table 1.

Evaluation 1: Reliability evaluation after standing for a long time Ink of Example 1 was used in an ink jet printer having a nozzle of 300 dpi in which a laminated PZT having a nozzle plate made of nickel was used for pressurizing a liquid chamber channel, and Comparative Example. After filling with 1 ink and leaving it in a capped state at room temperature for 3 months, perform cleaning operations such as wiping and suction 0 times and 1 time to print, and compare the pixel diameter and dot position accuracy before and after leaving. went. With 0 cleaning operations,
○ when there is no problem in pixel diameter and dot position accuracy, △ when recovering with one cleaning operation, × otherwise
And

[0056]

[Table 1]

Comparative Example 2 An ink was prepared in the same manner as in Example 1 except that the EHD amount of the ink of Example 1 was changed from 2% by weight to 5% by weight.

Comparative Example 3 An ink was prepared in the same manner as in Example 1 except that the amount of EHD in the ink of Example 1 was changed from 2% by weight to 0.05% by weight.

With respect to the above Comparative Example 2 ink and Comparative Example 3 ink, the image sharpness evaluation shown below and the above-mentioned reliability evaluation after long-term storage were carried out and compared with Example 1 ink. The results are shown in Table 2.

Evaluation 2: Image sharpness evaluation test 2-1: Image density evaluation A solid portion of 100% black printed on plain paper with each ink was
Reflective color spectrophotometric densitometer X-Rite 938 (X-Rit
The image density was measured using a product manufactured by e. Test 2-2: Evaluation of strikethrough A solid portion of 100% black printed on plain paper with each ink
Reflective color spectrophotometric densitometer X-Rite93 from the back side of the paper
8 (manufactured by X-Rite) using the image density (strike through)
Was measured. Test 2-3: Evaluation of bleeding The bleeding of the printed sample with each ink was visually evaluated. As the printing paper, commercially available recycled paper, copy paper, and inkjet-dedicated paper were used for printing. The evaluation was rated as ◯ when all three papers were good, and was rated as x when not evaluated.

[0061]

[Table 2]

Comparative Example 4 In the ink of Example 1, the type of colorant used was a dispersant-dispersed carbon black (manufactured by Dainichiseika Kogyo Co., Ltd.).
Comparative Example 4 ink was prepared with the same composition except that the above was changed to.

For this ink, the long-term reliability evaluation of Evaluation 1 above and the redispersibility evaluation shown below were carried out. The results are shown in Table 3.

Evaluation 3. Evaluation of redispersibility Regarding the ink of Example 1 and the ink of Comparative Example 4, the particle size distribution at the initial stage of ink preparation and leaving for 1 day in an environment of 40 ° C. and 20% were supplemented with pure water evaporated. The particle size distribution of the ink after stirring was measured. Microtrac particle size distribution meter 934
0-UPA was used.

[0065]

[Table 3]

In the ink of Example 1, the particle size did not change even after redispersion, whereas in the ink of Comparative Example 4, the particle size increased after redispersion and the reliability after long-term storage was poor.

Comparative Example 5 Ink of Comparative Example 5 was prepared with the same composition as in Example 1 except that the surfactant was changed to the nonionic surfactant BT-7 (Nikko Chemicals). When this ink was evaluated 2, the bleeding of the printed image was x.

Comparative Example 6 An ink of Comparative Example 6 was prepared with the following composition in the same manner as the ink of Example 1. <Composition of Black Ink> CAB-O-JET300 (manufactured by Cabot Specialty Chemicals, Inc.) 5% by weight EHD (manufactured by Kyowa Hakko Co., Ltd.) 2% by weight diethylene glycol 5% by weight glycerol 3% by weight ECTD-3NEX (Nikko Chemicals) 1 wt% Proxel XL (manufactured by ICI) 0.4 wt% Ion-exchanged water Remaining amount When this ink was evaluated for reliability after being left for a long period of evaluation 1, x was obtained.

Comparative Example 7 An ink of Comparative Example 7 was prepared in the same manner as the ink of Example 1 with the following composition. <Composition of Black Ink> CAB-O-JET300 (manufactured by Cabot Specialty Chemicals, Inc.) 5% by weight EHD (manufactured by Kyowa Hakko Co., Ltd.) 2% by weight 1,5-pentanediol 10% by weight glycerol 3% by weight ECTD- 3NEX (Nikko Chemicals) 1 wt% Proxel XL (manufactured by ICI) 0.4 wt% Ion-exchanged water Remaining amount When this ink is evaluated for reliability after being left for a long period of time, it becomes x. It was

[0070]

According to the present invention, according to the present invention, by using EHD having a content of a butyric acid ester compound in a specific range as a penetrant, safety and reliability are high, and a printed image can be obtained. It is now possible to provide an ink having a high density, a small amount of strike-through, and an image without bleeding.

Effect of claim 2: According to the present invention, EHD
By controlling the addition amount of the ink in a specific range, it is possible to provide an ink that has high reliability and can obtain a high-quality image.

Effect of Claim 3: According to the present invention, by using a specific colorant, it is possible to provide an ink having high weather resistance of a printed image and high reliability.

Effect of Claim 4: According to the present invention, by containing a specific surfactant, it is possible to provide a clear printed image which is quick-drying and has no character bleeding or boundary bleeding. .

Effect of claim 5: According to the present invention, by using a specific counter ion, it is possible to provide a more reliable ink.

Effect of claim 6 According to the present invention, by containing a specific wetting agent, it is possible to provide an ink having more excellent storage stability and ejection stability.

Effect of claim 7: According to the present invention, it is possible to provide a recording apparatus which can obtain a printed image in which the conventional drawbacks are eliminated.

Continued front page    (72) Inventor Akihiko Goto             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Hitoshi Arita             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Tetsuya Kaneko             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Nobutaka Nagata             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Tomoko Sekine, Inventor             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Masayuki Oyano             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Keiji Murakami             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Toshiro Tokuno             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh F term (reference) 2C056 EA05 EA13 FC01                 2H086 BA52 BA53 BA55 BA59 BA62                 4J039 BA04 BC07 BC09 BC19 BC20                       BE01 BE02 BE15 BE22 CA06                       EA35 EA38 EA47 GA24

Claims (7)

[Claims] 1. An ink containing water, a colorant dispersed and / or dissolved in water, a surfactant, a wetting agent, and 2-ethyl-1,3-hexanediol (hereinafter abbreviated as EHD), wherein the EHD is An ink for inkjet recording comprising EHD containing a butyrate compound in a range of 0.05 to 1% by weight. 2. The amount of EHD is 0.1 to 4 of the total amount of ink.
The ink for ink jet recording according to claim 1, which is in a range of weight%. 3. The colorant is a neutral or acidic carbon black, and the surface thereof is such that at least one functional group of a carbonyl group, a carboxyl group, a hydroxyl group, or a sulfone group or a salt thereof is bonded. It is a substance which can be dispersed and / or dissolved in water by a treatment without a dispersant.
Or the ink jet recording ink according to 2. 4. The surfactant is a surfactant represented by the following general formula (1) and is 0.5 to 3 of the total amount of ink.
The ink for inkjet recording according to any one of claims 1 to 3, wherein the ink is contained in a weight percentage. _{RO (CH 2 CH 2 O)} n CH 2 COOM (1) R: a linear or branched alkyl group having a carbon number of 13 or 14 n: 3 to 12 integer M: alkali metal, quaternary ammonium, quaternary Phosphonium or alkanolamine 5. The counter ion of the colorant and / or the counter ion of the surfactant contained in the ink is sodium, lithium and / or a quaternary ammonium or quaternary ammonium represented by the following general formula (2). The inkjet recording ink according to any one of claims 1 to 4, wherein the ink is phosphonium or an alkanolamine ion. [Chemical 1] Z: Nitrogen or phosphorus R _{1 to} R ₄ : hydrogen, an alkyl group having 1 to 4 carbon atoms, a hydroxyl group, or a halogenated alkyl group 6. The wetting agent is a mixture of glycerol and diethylene glycol, and is 10 to 10% of the total amount of the ink.
The ink for inkjet recording according to claim 1, wherein the ink is contained in an amount of 30% by weight. 7. An inkjet recording apparatus equipped with the inkjet recording ink according to claim 1.