JP2005298609A - Ink for inkjet and inkjet recording method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink for inkjet excellent in long-term preservation stability which exhibits an intermittent delivering property as good as an ink having incorporated thereinto urea or urea derivatives used for conventional inkjet recording and causes neither changes in tints of dyes nor precipitation generation by aggregation of dyes. <P>SOLUTION: The ink for inkjet comprises a water-soluble organic solvent A and a water-soluble organic solvent B represented by the formula: HOCH<SB>2</SB>(CH<SB>2</SB>)<SB>n</SB>CH<SB>2</SB>OH (wherein n is 1-6), each in amount of at least 6 mass%, and at least two dyes, where the water-soluble organic solvent A is a good solvent for all of the at least two dyes while the water-soluble organic solvent B is a poor solvent for all of the at least two dyes. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an inkjet ink having excellent intermittent ejection stability, and an inkjet recording method using the ink to improve intermittent ejection stability.

  Conventionally, for the purpose of improving the stability of intermittent ejection of ink jet ink, it is common to add urea, urea derivatives, or the like as a moisturizing agent in the ink in order to prevent clogging associated with water evaporation. (Patent Document 1). In addition, for the purpose of improving the stability of intermittent ink discharge, urea, urea derivatives, etc. are added to the ink as a dye dissolution aid in order to increase the solubility of the dye in water and various solvents. Is generally performed (Patent Document 2).

  However, some dyes cause dye color change or dye aggregation due to ammonium ions generated by urea decomposition, and if ink containing urea is stored for a long period of time, precipitates due to dye aggregation Occurs, and there is a problem that clogging may occur in an ink discharge port or an ink supply pipe of the ink jet recording apparatus.

JP-A-57-74372 JP-A-2-173168

  Accordingly, an object of the present invention is to provide excellent intermittent ejection properties as well as inks added with urea and urea derivatives used in conventional ink jet recording, and change in the color of the dye and the precipitation due to the aggregation of the dye. An object of the present invention is to provide an inkjet ink excellent in long-term storage stability that does not cause generation, and an inkjet recording method using the ink.

The above object is achieved by the present invention described below. That is, in the present invention, the water-soluble organic solvent A and the water-soluble organic solvent B represented by HOCH ₂ (CH ₂ ) _n CH ₂ OH (n = 1 to 6) are each 6 mass% or more, and two or more kinds. In an inkjet ink containing a dye, the water-soluble organic solvent A is a good solvent for all of the two or more dyes, and the water-soluble organic solvent B is used for all of the two or more dyes. An ink-jet ink is provided that is a poor solvent.

（式中、Ｒ₁及びＲ₂は各々独立に置換若しくは未置換のアルキル基、アリール基、アリールアルキル基、又は水素の何れかを表す。Ｒ₃及びＲ₅はそれぞれ独立に、カルボキシル基、スルホン酸基、リン酸基、又はそれらの塩の基、又はこれらの基で置換されたアルキル基を表す。Ｒ₄及びＲ₆はそれぞれ独立に、Ｒ₃及びＲ₅に対して定義した以外の基を表す。ｐ及びｒは、それぞれ独立に１乃至５の整数を表し、ｑ及びｓは、それぞれ独立に０乃至４の整数を表す。又、ｐ＋ｑが５以下の値を有し、ｒ＋ｓが５以下の値を有す。） In the present invention, the water-soluble organic solvent A is glycerin; the water-soluble organic solvent B is 1,5-pentanediol; one of the dyes is a dye having the following structure I Is preferred.

(Wherein R ₁ and R ₂ each independently represents a substituted or unsubstituted alkyl group, aryl group, arylalkyl group, or hydrogen. R ₃ and R ₅ each independently represent a carboxyl group, a sulfone group, or a sulfone group. An acid group, a phosphoric acid group, or a salt group thereof, or an alkyl group substituted with these groups, R ₄ and R ₆ are each independently a group other than those defined for R ₃ and R ₅ P and r each independently represent an integer of 1 to 5, q and s each independently represent an integer of 0 to 4. Further, p + q has a value of 5 or less, and r + s is 5 It has the following values.)

（上記式中、Ｍはアルカリ金属（例えばＬｉ、Ｎａ、Ｋ、Ｒｂ、Ｃｓ、Ｆｒ等）又はアンモニウムである。又、Ｒ₇はＯＨ、ＣＯＯＭ、Ｒ₈ＣＯＯＭ（Ｒ₈はＣ４〜Ｃ９のアルキル基）を表し、ｘ、ｙ、ｚはそれぞれ独立に０、１、２、３又は４である。） In the present invention, another one of the dyes is a dye having the following structure II;

(In the above formula, M is an alkali metal (eg, Li, Na, K, Rb, Cs, Fr, etc.) or ammonium, and R ₇ is OH, COOM, R ₈ COOM (R ₈ is a C4 to C9 alkyl). Group), x, y and z are each independently 0, 1, 2, 3 or 4.)

  The present invention also provides an ink jet recording method, wherein the ink jet ink of the present invention is heated and then discharged. In this method, it is preferable that the reached temperature is 25 ° C. or higher.

  According to the present invention, it has the same intermittent ejection stability as that of a conventional ink to which urea or a derivative thereof is added, and it does not cause precipitation due to dye color change and dye aggregation. An ink jet ink excellent in storage stability is provided, and according to the ink jet recording method using the ink of the present invention, recording having the above characteristics can be performed accurately.

Next, the present invention will be described in more detail with reference to the best mode for carrying out the invention. In the ink of the present invention, the water-soluble organic solvent A and the water-soluble organic solvent B represented by HOCH ₂ (CH ₂ ) _n CH ₂ OH (n = 1 to 6) are each 6 mass% or more, and two or more kinds. In an inkjet ink containing a dye, the water-soluble organic solvent A is a good solvent for all of the two or more dyes, and the water-soluble organic solvent B is used for all of the two or more dyes. In contrast, the ink for ink-jet recording is characterized by being a poor solvent.

Hereinafter, each of the materials constituting the present invention will be described. The ink of the present invention contains 6% by mass or more of a water-soluble organic solvent A and a water-soluble organic solvent B represented by HOCH ₂ (CH ₂ ) _n CH ₂ OH (n = 1 to 6). To do. Here, the water-soluble organic solvent A should just be a good solvent with respect to the 2 or more types of dye mentioned later. The water-soluble organic solvent A can be used depending on the combination of two or more dyes to be combined. This is because, depending on the selected dye, even the same solvent can be a good solvent or a poor solvent. For this reason, it is necessary to select the water-soluble organic solvent A so as to satisfy the above requirements with a set of two or more dyes to be combined. However, the water-soluble organic solvent A is not particularly limited as long as the requirement is satisfied. However, although the water-soluble organic solvent A is not particularly limited as described above, it is particularly preferable to use glycerin by appropriately selecting two kinds of dyes, particularly for the intermittent ejection stability which is the object of the present invention. Since the improvement effect can be exhibited greatly, it is preferable.

  A preferable content of the water-soluble organic solvent A used in the present invention is preferably 6% or more, and preferably 20% or less on a mass basis. Further, it is more preferably within 15%. If the content of the water-soluble organic solvent A is less than 6%, the effect of the stability of intermittent discharge, which is the object of the present invention, cannot be obtained sufficiently, and if it exceeds 20%, the intermittent function is the object of the present invention. This is because it is difficult to sufficiently obtain the effect of stability of the discharge property.

The water-soluble organic solvent B represented by HOCH ₂ (CH ₂ ) _n CH ₂ OH (n = 1 to 6) used in the present invention is preferably 1,5-pentanediol, and is 6% on a mass basis. The above is preferable, and it is preferably used within 20%. Further, it is more preferably used within 15%. If the content of the water-soluble organic solvent B is less than 6%, the effect of the stability of intermittent discharge, which is the object of the present invention, cannot be sufficiently obtained, and if it exceeds 20%, the intermittent function is the object of the present invention. This is because it is difficult to sufficiently obtain the effect of stability of the discharge property.

A preferred ratio of the water-soluble organic solvent A and the water-soluble organic solvent B represented by HOCH ₂ (CH ₂ ) _n CH ₂ OH (n = 1 to 6) is 3: 1 to 1: 3 on a mass basis. Is within the range.

In the present invention, the water-soluble organic solvent A and the water-soluble organic solvent B represented by HOCH ₂ (CH ₂ ) _n CH ₂ OH (n = 1 to 6) are contained in an amount of 6% by mass or more. The water-soluble organic solvent can be contained. Specific examples of water-soluble organic solvents that can be used in the present invention include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and tert-butyl alcohol. Alkyl alcohols having 1 to 5 carbon atoms such as dimethylformamide and dimethylacetamide; ketones or ketoalcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane Oxyethylene such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, polypropylene glycol or the like; Xylene-propylene copolymers; alkylene glycols containing 2 to 6 carbon atoms in alkylene groups such as ethylene glycol, propylene glycol, trimethylene glycol, triethylene glycol, 1,2,6-hexanetriol; trimethylolpropane; Lower alkyl ethers such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether; triethylene glycol dimethyl (or ethyl) ether, tetraethylene glycol dimethyl (or ethyl) ) Lower dialkyl ethers of polyhydric alcohols such as ether; alkanolamines such as monoethanolamine, diethanolamine, triethanolamine; Ruhoran, N- methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone. The water-soluble organic solvents as described above can be used alone or as a mixture.

The content of the water-soluble organic solvent as described above contained in the ink of the present invention is not particularly limited, but is preferably in the range of 50% by mass or less with respect to the total mass of the ink. In particular, the ratio of the sum of the water-soluble organic solvent A and the water-soluble organic solvent B represented by HOCH ₂ (CH ₂ ) _n CH ₂ OH (n = 1 to 6) to the water-soluble organic solvent is 1 on a mass basis. : It is preferable to be in the range of 2 or less.

  Further, the present invention contains two or more dyes, the water-soluble organic solvent A is a good solvent for all of the two or more dyes, and the water-soluble organic solvent B is the two kinds. The dye is not particularly limited as long as it has a requirement that it is a poor solvent for all of the above dyes, but a dye having the structure represented by the following structure I is used for the two or more dyes. As one, it can be used particularly preferably.

(Wherein R ₁ and R ₂ each independently represents a substituted or unsubstituted alkyl group, aryl group, arylalkyl group, or hydrogen. R ₃ and R ₅ each independently represent a carboxyl group, a sulfone group, or a sulfone group. An acid group, a phosphoric acid group, or a salt group thereof, or an alkyl group substituted with these groups, R ₄ and R ₆ are each independently a group other than those defined for R ₃ and R ₅ P and r each independently represent an integer of 1 to 5, q and s each independently represent an integer of 0 to 4. Further, p + q has a value of 5 or less, and r + s is 5 It has the following values.)

  Here, preferable examples of the dye include the dyes shown in Table 1 below, but the present invention is not limited to the following exemplified dyes.

（上記式中、Ｍはアルカリ金属（例えばＬｉ、Ｎａ、Ｋ、Ｒｂ、Ｃｓ、Ｆｒ等）又はアンモニウムである。又、Ｒ₇はＯＨ、ＣＯＯＭ、Ｒ₈ＣＯＯＭ（Ｒ₈はＣ４〜Ｃ９のアルキル基）を表し、ｘ、ｙ、ｚはそれぞれ独立に０、１、２、３又は４である。） Furthermore, a dye having a structure represented by the following structure II as another one of the above dyes can be particularly preferably used as another one of the two or more kinds of dyes.

(In the above formula, M is an alkali metal (eg, Li, Na, K, Rb, Cs, Fr, etc.) or ammonium, and R ₇ is OH, COOM, R ₈ COOM (R ₈ is a C4 to C9 alkyl). Group), x, y and z are each independently 0, 1, 2, 3 or 4.)

  Here, although it is a definition of a poor solvent and a good solvent, in this invention, when a powdery dye is stirred in a sealed state for 24 hours in a 25 ° C. environment, the solvent dissolves less than 5% by mass of the dye. Is a poor solvent, and a solvent that dissolves 5% by mass or more is defined as a good solvent. About how much the dye is dissolved, for example, a calibration curve is made by measuring the absorbance of the dye with an aqueous dye solution in which 1%, 5%, and 10% by weight of the dye is dissolved in water. By measuring the absorbance of a filtered solution containing 10% by mass of the dye and dissolved under the above requirements, it can be easily determined from the absorbance ratio. A preferable content of the two types of dyes in the ink is 0.1 to 10% by mass in terms of mass in terms of total dyes.

  Further, the content of water contained in the ink of the present invention is preferably in the range of 50 to 95% by mass with respect to the total mass of the ink. Further, the ink of the present invention may be added with a surfactant, an antifoaming agent, an antiseptic, an antifungal agent or the like as necessary in addition to the above-described components in order to obtain an ink having a desired physical property value. Can do.

The ink of the present invention is more effective when used in an ink jet printer having an ink jet head having a temperature adjusting function. Although the details of the mechanism by which the ink of the present invention is effective for the stability of intermittent ejection are unclear, it is represented by water-soluble organic solvent A and HOCH ₂ (CH ₂ ) _n CH ₂ OH (n = 1 to 6). The water-soluble organic solvent B contains an amount specified in the present invention, and further contains two or more dyes, and the water-soluble organic solvent A is a good solvent for all the two or more dyes. When there is a relationship and the water-soluble organic solvent B is a poor solvent for all of the two or more dyes, a thin film that does not affect ejection is formed in the vicinity of the nozzle to suppress ink evaporation. I think that is because. This phenomenon becomes more prominent when the ink is ejected in a state of having a temperature adjustment function and the temperature is raised. Therefore, it is more effective when used in an ink jet printer having an ink jet head having the temperature adjustment function. I guess that.

  As another embodiment of the present invention, there is an ink jet recording method in which the ink jet ink is discharged in a heated state. In addition, the ink jet recording method is particularly effective when the temperature reached is 25 ° C. or higher, and the ink jet recording method is characterized in that the temperature reached is 25 ° C. or higher.

  FIG. 1 shows an example of an ink jet recording apparatus, FIG. 2 shows an example of an ink jet cartridge, and FIG. 2 shows an example of a head that can discharge ink jet ink that achieves the ink jet recording method in a heated (temperature-controlled) state. Listed in FIG.

  FIG. 1 is a perspective view showing a configuration of a preferred ink jet recording apparatus to which the present invention is implemented or applied. In FIG. 1, 5001 is an ink tank (IT), and 5012 is a recording head (IJH) coupled thereto. As shown in FIG. 2, an integral replaceable cartridge (IJC) is formed by 5001 ink tanks and 5012 recording heads. Reference numeral 5014 denotes a carriage (HC) for attaching the cartridge (IJC) to the printer main body, and reference numeral 5003 denotes a guide for scanning the carriage in the sub-scanning direction.

  Reference numeral 5000 denotes a platen roller for scanning a printing material indicated by P in the main scanning direction. Reference numeral 5024 denotes a temperature sensor for measuring the environmental temperature in the apparatus. The carriage 5014 has a flexible cable (not shown) for supplying a signal pulse current for driving and a head temperature adjusting current to the recording head 5012, and an electric circuit for controlling the printer (the temperature sensor described above). 5012 etc.) and is connected to a printed board (not shown).

  FIG. 2 shows a replaceable cartridge, and reference numeral 5029 denotes a nozzle portion for ejecting ink droplets. Further, the ink jet recording apparatus IJRA having the above configuration will be described in detail. In this recording apparatus IJRA, a carriage HC that engages with a spiral groove 5004 of a lead screw 5005 that rotates via driving force transmission gears 5011 and 5009 in conjunction with forward and reverse rotation of a driving motor 5013 has a pin (not shown). And is reciprocated in the directions of arrows a and b. Reference numeral 5002 denotes a paper pressing plate that presses the paper against the platen 5000 in the carriage movement direction. Reference numerals 5007 and 5008 denote home position detecting means for confirming the presence of the lever 5006 of the carriage HC in this region by a photocoupler and switching the rotation direction of the motor 5013 and the like. Reference numeral 5016 denotes a member that supports a cap member 5022 that caps the front surface of the recording head, and reference numeral 5015 denotes suction means for sucking the inside of the cap. The suction recovery of the recording head 5012 is performed through an opening 5023 in the cap.

  Reference numeral 5017 denotes a cleaning blade, and reference numeral 5019 denotes a member that enables the blade 5017 to move in the front-rear direction, and these are supported by a main body support plate 5018. Needless to say, the blade is not in this form, and a known cleaning blade can be applied to this example. Reference numeral 5021 denotes a lever for starting suction for suction recovery, which moves in accordance with the movement of the cam 5020 engaged with the carriage HC, and the driving force from the driving motor is moved by a known transmission means such as clutch switching. Be controlled.

  These capping, cleaning, and suction recovery are configured such that when the carriage HC comes to the home position side region, desired processing can be performed at the corresponding position by the action of the lead screw 5005, but at a known timing. Any of these examples can be applied as long as a desired operation is performed.

  FIG. 3 shows details of the recording head 5012, and a heater board 5100 formed by a semiconductor manufacturing process is provided on the upper surface of the support 5300. The heater board 5100 is provided with a temperature adjusting heater (temperature increasing heater) 5110 for keeping the recording head 5012 warm and adjusting the temperature, which is formed by the same semiconductor manufacturing process. Reference numeral 5200 denotes a wiring board disposed on the support 5300. The wiring board 5200 is wired to the temperature adjustment heater 5110 and the discharge (main) heater 5113 by wire bonding or the like (the wiring is not suitable). (Illustrated). In addition, the heater 5110 for temperature control may be obtained by attaching a heater member formed by a process different from the heater board 5100 to the support 5300 or the like.

  Reference numeral 5114 denotes a bubble generated by being heated by the discharge heater 5113. Reference numeral 5115 denotes an ejected ink droplet. Reference numeral 5112 denotes a common liquid chamber for discharging ink into the recording head.

  EXAMPLES Next, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited by the following Example, unless the summary is exceeded. In the text, “parts” and “%” are based on mass unless otherwise specified.

[Example 1]
The following components were mixed, sufficiently stirred and dissolved, and then filtered under pressure with a microfilter having a pore size of 0.2 μm (manufactured by Fuji Film) to prepare the ink of the present invention.
10 parts of glycerin 10 parts of 1,5-pentanediol A mixture of a lithium salt and a sodium salt of a dye having the following structure I-1 (molar ratio Li
Salt: Na salt = 2: 1) 3 parts, dye of the following structure II-1 1 part, water 76 parts

［ただし、（ｍ＝１、ｎ＝２）、（ｍ＝１、ｎ＝３）、（ｍ＝２、ｎ＝１）、（ｍ＝２、ｎ＝２）、（ｍ＝３、ｎ＝０）、（ｍ＝３、ｎ＝１）、（ｍ＝４、ｎ＝０）の混合物。］

[However, (m = 1, n = 2), (m = 1, n = 3), (m = 2, n = 1), (m = 2, n = 2), (m = 3, n = 0), (m = 3, n = 1), (m = 4, n = 0). ]

  In addition, after containing 5 g of a powdery dye of a mixture of a lithium salt and a sodium salt of the dye of the above structure I-1 (molar ratio Li salt: Na salt = 2: 1) in 20 g of glycerin, at 25 ° C. After stirring in a sealed state for 24 hours, the solubility was measured by measuring the absorbance, and the solubility was 20% (upper limit value in this measurement method). Similarly, when the solubility in 1,5-pentanediol was measured, the solubility was 1.5%. Next, when the solubility in glycerin of the dye having the above structure II-1 was measured by the same method, it was 16.5%, and the solubility in 1,5-pentanediol was 0.9%. From this, glycerin is a good solvent for the mixture of the lithium salt and sodium salt of the dye of structure I-1 (molar ratio Li salt: Na salt = 2: 1) and the dye of structure II-1; It was confirmed that both 5-pentanediol was a poor solvent.

[Example 2]
The following components were mixed, sufficiently stirred and dissolved, and then filtered under pressure with a microfilter having a pore size of 0.2 μm (manufactured by Fuji Film) to prepare the ink of the present invention.
-Glycerol 10 parts-1,5-pentanediol 6 parts-Ethylene glycol 8 parts-Mixture of lithium salt and sodium salt of the dye of the above structure I-1 (molar ratio Li
Salt: Na salt = 2: 1) 3 parts, dye of structure II-1 1 part, water 72 parts

  In addition, after containing 5 g of a powdery dye of a mixture of a lithium salt and a sodium salt of the dye of the above structure I-1 (molar ratio Li salt: Na salt = 2: 1) in 20 g of ethylene glycol, it was placed in a 25 ° C. environment. After stirring for 24 hours in a sealed state, the solubility was measured by measuring the absorbance, and the solubility was 20% (upper limit value in this measurement method). Further, when the solubility in ethylene glycol of the dye having the above structure II-1 was measured by the same method, it was 20% (upper limit value in this measurement method).

[Example 3]
The following components were mixed, sufficiently stirred and dissolved, and then filtered under pressure with a microfilter having a pore size of 0.2 μm (manufactured by Fuji Film) to prepare the ink of the present invention.
6 parts of glycerin 10 parts of 1,5-pentanediol 9 parts of ethylene glycol A mixture of the lithium salt and sodium salt of the dye of the above structure I-1 (molar ratio Li
Salt: Na salt = 2: 1) 3 parts, dye of structure II-1 1 part, water 71 parts

[Comparative Example 1]
The following components were mixed, sufficiently stirred and dissolved, and then filtered under pressure with a microfilter (manufactured by Fuji Film) having a pore size of 0.2 μm to prepare a comparative ink.
-Glycerin 25 parts-Lithium salt and sodium salt mixture of the dye of structure I-1 (molar ratio Li
Salt: Na salt = 2: 1) 3 parts, dye of structure II-1 1 part, water 71 parts

[Comparative Example 2]
The following components were mixed, sufficiently stirred and dissolved, and then filtered under pressure with a microfilter (manufactured by Fuji Film) having a pore size of 0.2 μm to prepare a comparative ink.
-25 parts of 1,5-pentanediol-Mixture of lithium and sodium salts of the dye of structure I-1 above (molar ratio Li
Salt: Na salt = 2: 1) 3 parts, dye of structure II-1 1 part, water 71 parts

[Comparative Example 3]
The following components were mixed, sufficiently stirred and dissolved, and then filtered under pressure with a microfilter (manufactured by Fuji Film) having a pore size of 0.2 μm to prepare a comparative ink.
-Glycerin 20 parts-1,5-pentanediol 5 parts-Lithium salt and sodium salt mixture (molar ratio Li)
Salt: Na salt = 2: 1) 3 parts, dye of structure II-1 1 part, water 71 parts

[Comparative Example 4]
The following components were mixed, sufficiently stirred and dissolved, and then filtered under pressure with a microfilter (manufactured by Fuji Film) having a pore size of 0.2 μm to prepare a comparative ink.
-Glycerol 10 parts-1,5-pentanediol 10 parts-Lithium salt and sodium salt mixture (molar ratio Li)
Salt: Na salt = 2: 1) 4 parts, water 76 parts

[Comparative Example 5]
The following components were mixed, sufficiently stirred and dissolved, and then filtered under pressure with a microfilter (manufactured by Fuji Film) having a pore size of 0.2 μm to prepare a comparative ink.
-Glycerol 10 parts-1,5-pentanediol 6 parts-Ethylene glycol 8 parts-Mixture of lithium salt and sodium salt of the dye of the above structure I-1 (molar ratio Li
Salt: Na salt = 2: 1) 4 parts, water 72 parts

[Comparative Example 6]
The following components were mixed, sufficiently stirred and dissolved, and then filtered under pressure with a microfilter (manufactured by Fuji Film) having a pore size of 0.2 μm to prepare a comparative ink.
6 parts of glycerin 10 parts of 1,5-pentanediol 9 parts of ethylene glycol A mixture of the lithium salt and sodium salt of the dye of the above structure I-1 (molar ratio Li
Salt: Na salt = 2: 1) 4 parts, 71 parts of water

<Evaluation 1>
(Intermittent ejection stability evaluation method and evaluation criteria)
Using the inks of Examples 1 to 3 and Comparative Examples 1 to 6, the intermittent ejection stability of the inkjet head was evaluated. Evaluation was performed using a Canon BJS-950i modified machine. First, in a temperature of 15 ° C. and a humidity of 10%, vertical ruled lines were printed at a certain discharge pause time interval under the condition that the temperature of the ink in the nozzle portion of the inkjet head did not rise, and a fixed pause time was provided. Thereafter, the vertical ruled lines formed by first discharging were visually evaluated according to the following criteria.
A: The vertical ruled lines are not disturbed at all and can be printed normally.
○: A slight disorder that cannot be visually confirmed on the vertical ruled lines is confirmed.
Δ: Slight disturbance to the extent that it can be visually confirmed on the vertical ruled lines is confirmed.
X: Non-ejection and disorder are clearly confirmed on the vertical ruled line.

<Evaluation 2>
(Intermittent ejection stability evaluation method and evaluation criteria)
Using the inks of Examples 1 to 3 and Comparative Examples 1 to 6, the intermittent ejection stability of the inkjet head was evaluated. The evaluation was performed under the same evaluation criteria in the same environment as Evaluation 1 using a Canon BJS-950i remodeling machine in which the ink in the nozzle part of the inkjet head was kept at 25 ° C. just before ejection.
The results of Evaluation 1 and Evaluation 2 are shown in Table 2 below.

  As is apparent from Table 2 above, the inks of Examples 1 to 3 were able to perform normal ink ejection even after a certain ejection pause time, and it was confirmed that these inks were excellent in intermittent ejection stability. It was also confirmed that the ink jet recording method, which is a method of evaluation 2, which is characterized by raising the temperature of the ink jet ink immediately before ejection, is more effective.

  According to the present invention, it is excellent in good intermittent ejection properties as in the case of inks added with urea or urea derivatives used in conventional ink jet recording, and changes in the color of the dye and generation of precipitates due to aggregation of the dye. An inkjet ink excellent in long-term storage stability without causing ink and an inkjet recording method using the ink are provided.

1 is a perspective view illustrating a configuration of a preferred ink jet recording apparatus to which the present invention is implemented or applied. It is a perspective view which shows a replaceable cartridge. FIG. 3 is a cross-sectional view of a recording head.

Explanation of symbols

5000: Platen roller 5001: Ink tank (IT)
5002: Paper pressing plate 5003: Guide 5004: Spiral groove 5005: Lead screw 5006: Lever 5007: Photocoupler 5008: Photocoupler 5009: Driving force transmission gear 5010: Driving force transmission gear 5011: Driving force transmission gear 5012: Recording head ( IJH)
5013: Drive motor 5014: Carriage (HC)
5015: In-cap suction means 5016: Cap support member 5017: Cleaning blade 5018: Main body support plate 5019: Cleaning blade movable member 5020: Cam 5022: Cap member 5023: In-cap opening 5024: Temperature sensor 5029: Nozzle portion 5100: Heater Board 5110: Heating heater (heating heater)
5112: Common liquid chamber 5113: Discharge (main) heater 5114: Bubble 5115: Ink droplet 5200: Wiring substrate 5300: Support

Claims (8)

Ink jet containing water-soluble organic solvent A and water-soluble organic solvent B represented by HOCH ₂ (CH ₂ ) _n CH ₂ OH (n = 1 to 6), respectively, in an amount of 6% by mass or more and two or more dyes In the ink, the water-soluble organic solvent A is a good solvent for all of the two or more dyes, and the water-soluble organic solvent B is a poor solvent for all of the two or more dyes. An inkjet ink characterized by having a relationship.   The inkjet ink according to claim 1, wherein the water-soluble organic solvent A is glycerin.   The inkjet ink according to claim 1, wherein the water-soluble organic solvent B is 1,5-pentanediol. The ink-jet ink according to any one of claims 1 to 3, wherein one of the dyes is a dye having the following structure I.

(Wherein R ₁ and R ₂ each independently represents a substituted or unsubstituted alkyl group, aryl group, arylalkyl group, or hydrogen. R ₃ and R ₅ each independently represent a carboxyl group, a sulfone group, or a sulfone group. An acid group, a phosphoric acid group, or a salt group thereof, or an alkyl group substituted with these groups, R ₄ and R ₆ are each independently a group other than those defined for R ₃ and R ₅ P and r each independently represent an integer of 1 to 5, q and s each independently represent an integer of 0 to 4. Further, p + q has a value of 5 or less, and r + s is 5 It has the following values.) The inkjet ink according to any one of claims 1 to 3, wherein another one of the dyes is a dye having the following structure II.

(In the above formula, M is an alkali metal or ammonium. R ₇ represents OH, COOM, or R ₈ COOM (R ₈ is a C4 to C9 alkyl group), and x, y, and z are each independently 0. , 1, 2, 3 or 4.)   The inkjet ink according to any one of claims 1 to 5, wherein the inkjet ink is an inkjet printer ink having an inkjet head having a temperature adjusting function.   An ink jet recording method, comprising: heating the ink jet ink according to claim 1, and then discharging the ink. The inkjet recording method according to claim 6, wherein the temperature reached is 25 ° C. or higher.

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