JPH05339527A - Water-based ink for inkjet recording - Google Patents

Abstract

PURPOSE:To obtain the title ink which permits adjustment of pH without detriment to the stability of dye solution by incorporating a colorant, a water-soluble organic solvent and a hydroxylated carboxylic acid. CONSTITUTION:The title ink is obtained by incorporating a colorant, a water-soluble organic solvent and a hydroxylated carboxylic acid [preferably at least one compound selected from compounds of formula I (wherein n is 0-5) and compounds of formula II (wherein X is H, OH or COOH; Y is H or OH, provided that at least one of X and Y is OH; Z is H or COOH; and m is 0 or 1)]. While water-base inks generally exhibit various pH values depending on the effect of a colorant, an antibacterial mildewproofing agent, a chelating agent, a penetrant, etc., the pH of an ink is often limited depending on the material of a portion in contact with the ink, and the present ink has a pH which can be adjusted without detriment to the stability of dye solution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based ink for ink jet recording, and more particularly to an ink whose pH is adjusted without impairing the dissolution stability of a colorant, especially a dye.

[0002]

2. Description of the Related Art As ink jet recording inks, water-based inks using water as a main solvent and oil-based inks using an organic solvent as a main solvent are generally used. Printed images using water-based inks are generally inferior in water resistance, but because the main solvent is water, they are excellent in safety, and because they can provide printed images of excellent quality, they are the mainstream of inkjet recording. Has become.

On the other hand, the drawback of the ink jet recording system is that
It is easy to cause ink ejection abnormalities due to nozzle clogging, changes in ink physical properties (eg, viscosity, surface tension) over time, and various other factors, which is the biggest factor preventing the spread of inkjet recording. ing.

As an ink jet recording system, a so-called electric field control system is used in which ink is ejected by using electrostatic attraction; a so-called drop-on-demand system (pressure pulse is used in which ink is ejected by utilizing vibration pressure of a piezo element). Method); so-called bubble jet method in which ink is ejected by using the pressure generated by forming and growing bubbles by high heat; ink is applied by applying pressure with a pump after the nozzle and simultaneously applying high-frequency vibration with a piezo element. Charge control method (continuous method) in which the ink is applied to the ink droplets by the charging electrode, and then the ink droplets charged by the control electrode are controlled; a spark is generated in the ink under high voltage application condition. , Various ink jets such as the so-called spark jet method that ejects ink with its explosive force Tsu DOO recording method has been proposed, these methods, it is possible to obtain an image of extremely high definition.

The pH of the water-based ink shows various numerical values due to the effects of colorants, antibacterial and antifungal agents, chelating agents, penetrating agents, etc., but the pH of the ink is limited depending on the material in contact with the ink. In many cases, it is necessary to adjust the pH of the ink within a desired range.

As a method of increasing the pH of the ink, a method using alkanolamine or a hydroxide of an alkali metal has been proposed. As a method of lowering the pH of the ink, generally, an inorganic acid or an organic acid is added. Stated.

[0007]

The addition of an inorganic acid has a problem that it impairs the dissolution stability of a colorant and easily corrodes a metal material, and some organic acids have the same problem. . Note that some organic acids have odors, so caution should be exercised in their selection.

An object of the present invention is to provide an ink whose pH can be adjusted without impairing the dissolution stability of the colorant.

[0009]

The present inventors have completed the present invention as a result of intensive studies to solve the above problems.

That is, the present invention provides a water-based ink for jet recording which is characterized by containing a colorant, a water-soluble organic solvent and a carboxylic acid having a hydroxyl group.

The carboxylic acid having a hydroxyl group used in the present invention is represented by the general formula (1)

[0012]

[Formula 3] _{HO- (CH 2 CH 2 O)} n -CH 2 -COOH

(Wherein n represents an integer of 0 to 5) and the general formula (2).

[0014]

Embedded image X—CH ₂ —C (Y) (Z) C _m H _2m —COOH

(Wherein X represents H, OH or COOH, Y represents H or OH, Z represents H or COOH, and at least one of X and Y represents OH, and m represents 0. Alternatively, a compound selected from the group consisting of compounds represented by 1) is preferable.

Specific examples of the carboxylic acid having a hydroxyl group used in the present invention include the following.

[0017]

[Table 1]

The amount of the carboxylic acid having a hydroxyl group used in the present invention cannot be unconditionally specified because the pH of the ink varies depending on the desired pH and the colorants, auxiliaries and the like to be combined, but it is 0 in the ink composition. The range of 0.0001 to 10% by weight is preferable. In addition, these substances can be used alone or in combination.

The aqueous ink composition for ink-jet recording of the present invention mainly contains a colorant, a water-soluble organic solvent and water, and if necessary, an auxiliary agent.

The colorant is preferably a water-soluble dye,
Any water-soluble dye can be used, and it can be selected from acid dyes, basic dyes, direct dyes, reactive dyes, disperse dyes, food dyes, optical brighteners and the like.

Examples of acid dyes include C.I. I. Acid Black 1, 2, 7, 16, 17, 24, 26,
28, 31, 41, 48, 52, 58, 60, 63, 9
4,107,109,112,118,119,12
1,122,131,155,156; C.I. I. Acid Yellow 1,3,4,7,11,12,13,1
4,17,18,19,23,25,29,34,3
6,38,40,41,42,44,49,53,5
5,59,61,71,72,76,78,79,9
9,111,114,116,122,135,14
2, 161, 172; C.I. I. Acid Orange 7,
8, 10, 19, 20, 24, 28, 33, 41, 4
5,51,56,64; C.I. I. Acid Red 1,
4,6,8,13,14,15,18,19,21,2
6,27,30,32,34,35,37,40,4
2, 51, 52, 54, 57, 80, 82, 83, 8
5,87,88,89,92,94,97,106,1
08,110,111,114,115,119,12
9,131,133,134,135,143,14
4,152,154,155,172,176,18
0,184,186,187,249,254,25
6,289,317,318; C.I. I. Acid Violet 7,11,15,34,35,41,43,4
9, 51, 75; C.I. I. Acid Blue 1,7,
9,15,22,23,25,27,29,40,4
1,43,45,49,51,53,55,56,5
9, 62, 78, 80, 81, 83, 90, 92, 9
3,102,104,111,113,117,12
0,124,126,138,145,167,17
1,175,183,229,234,236,24
9; C.I. I. Acid Green 3,9,12,16,1
9, 20, 25, 27, 41, 44; C.I. I. Acid Brown 4, 14 and the like.

Examples of the basic dye include C.I. I. Basic Black 2,8; C.I. I. Basic Yellow 1, 2, 11, 12, 14, 21, 32, 36; C.I.
I. Basic Orange 2,15,21,22; C.I.
I. Basic Red 1, 2, 9, 12, 13, 3
7; C.I. I. Basic Violet 1,3,7,1
0,14; C.I. I. Basic Blue 1, 3, 5,
7, 9, 24, 25, 26, 28, 29; C.I. I. Basic Green 1,4; C.I. I. Basic brown 1, 12 and the like can be mentioned.

Examples of direct dyes include C.I. I. Direct Black 2,4,9,11,14,17,1
9, 22, 27, 32, 36, 38, 41, 48, 4
9,51,56,62,71,74,75,77,7
8, 80, 105, 106, 107, 108, 112,
113, 117, 132, 146, 154, 168, 1
71, 194; C.I. I. Direct Yellow 1, 2,
4,8,11,12,24,26,27,28,33,
34, 39, 41, 42, 44, 48, 502, 51,
58, 72, 85, 86, 87, 88, 98, 100,
110, 127, 135, 141, 142, 144;
C. I. Direct Orange 6,8,10,26,2
9, 41, 49, 51, 102; C.I. I. direct
Red 1, 2, 4, 8, 9, 11, 13, 152, 1
7, 20, 23, 24, 28, 31, 33, 37, 3
9,44,46,47,48,51,59,62,6
3,73,75,77,80,81,83,84,8
5,87,89,90,94,95,99,101,1
08,110,145,189,197,220,22
4,2252,226,227,230,250,25
4,256,257; C.I. I. Direct Violet 1,7,9,12,35,48,51,90,94;
C. I. Direct Blue 1,2,6,8,15,2
2,25,34,69,70,71,72,75,7
6,78,80,81,82,83,86,90,9
8, 106, 108, 110, 120, 123, 15
8,163,165,192,193,194,19
5,196,199,200,201,202,20
3,207,218,236,237,239,24
6,258,287; C.I. I. Direct Green 1, 6, 8, 28, 33, 37, 63, 64; C.I. I.
Direct Brown 1A, 2, 6, 25, 27, 4
4,58,95,100,101,106,112,1
73, 194, 195, 209, 210, 211 and the like.

Examples of reactive dyes include C.I. I. Reactive Black 1,3,5,6,8,12,1
4; C.I. I. Reactive Yellow 1, 2, 3, 1
3,14,15,17; C.I. I. Reactive Orange 2,5,7,16,20,24; C.I. I. Reactive Red 6,7,11,12,15,17,21,2
3,24,35,36,42,63,66,84,18
4; C.I. I. Reactive

Violet 2, 4, 5, 8, 9; C.I.
I. Reactive Blue 2,5,7,12,13,1
4,15,17,18,19,20,21,25,2
7, 28, 37, 38, 40, 41; C.I. I. Reactive Green 5,7; C.I. I. Reactive Brown 1, 7, 16 and the like can be mentioned.

Examples of food dyes include C.I. I. Hood Black 1, 2; C.I. I. Hood yellow 2,
4,5; C.I. I. Hood Red 2,3,7,9,1
4, 52, 87, 92, 94, 102, 104, 10
5,106; C.I. I. Hood Violet 2: C.I.
I. Food Blue 1, 2; C.I. I. Food green 2, 3 etc. are mentioned.

Other water-soluble dyes include, for example, "Kayaset Black 9A", "Direct Deep Black XA" and "Direct Special Black AXN" manufactured by Nippon Kayaku Co .; Special Black SP Liquid "," Biscript
"Black SP Liquid", "Levacell Turquoise Blue KS-6GLL", "Pyranin";"JI.BK-2","JI.BK-3" manufactured by Sumitomo Chemical Co., Ltd .; "JP-K81L" manufactured by Orient Chemical Co., Ltd. , "JP-K127
L "," JPK-139 "; C.I. I. Florescent
Brightening Agents 14, 22, 24, 3
2, 84, 85, 86, 87, 90, 134, 166
167, 169, 175, 176, 177 and the like.

A pigment can also be used as the colorant, and can be selected from inorganic pigments, organic pigments and the like.

These colorants may be used alone or in combination of two or more, but it is necessary to use a colorant which is stable in dissolution or dispersion at the pH of the ink adjusted by the compound of the present invention. The amount of the colorant used in the ink composition is preferably in the range of 0.1 to 10% by weight.

The water-soluble organic solvent is used for preventing solidification of the ink due to evaporation of water, for ensuring redissolvability in water and ink even when solidified, and for shortening the penetration time of the ink into plain paper. Specifically, glycols such as ethylene glycol, diethylene glycol, polyethylene glycol and glycerin; glycol ethers such as ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether and ethylene glycol monophenyl ether; N -Pyrrolidones such as methyl-2-pyrrolidone; alkanolamines such as triethanolamine; and alcohols such as methanol, ethanol and isopropyl alcohol. Call the like; dimethyl sulfoxide and the like.

These water-soluble organic solvents may be used alone or in combination in consideration of the hygroscopicity, moisture retention of the solvent, dye solubility, pigment dispersibility, ink viscosity, penetration time into plain paper, and the like. It is desirable that the amount used in the ink composition is in the range of 1 to 90% by weight.

As the water, it is necessary to use water having a purity equal to or higher than that of ion-exchanged water in order to dissolve the dye and to prevent clogging of the nozzle due to heavy metal ions. The amount used in the ink composition is preferably in the range of 5 to 95% by weight.

As the auxiliaries, antibacterial and antifungal agents, sequestering agents, pigment dispersants, surfactants, water-soluble polymers, water-soluble resins and the like may be used. By combining with an auxiliary agent for adjusting the pH of the ink such as alkanolamine or hydroxide of alkali metal to the alkali side, an ink having a small pH change can be obtained.

The use of the ink composition of the present invention is not limited to ink jet recording, and it can be widely used as ink for felt pens and plotters.

[0035]

EXAMPLES The present invention will be described below with reference to examples. In the examples, "%" represents "% by weight".

Example 1 Compound of Specific Example 1 0.01% C.I. I. Direct Yellow 44 1.5% Diethylene glycol 45.0% "Proxel GXL" 0.1% (antibacterial / antifungal agent ICC Japan Co., Ltd.) Ion-exchanged water 53.39%

The above components were mixed, sufficiently dissolved at room temperature, and then filtered with a 0.45 micron membrane filter to obtain an aqueous ink for ink jet recording.
The pH of the ink at this time was 7.1 at 25 ° C.
The pH of the ink obtained by omitting the compound of Example 1 from the above composition was 10.0.

The obtained ink was filled in a Teflon container and 6
There was no change in the physical properties of the ink even after standing for 1 year at 0 ° C. and 5 ° C., and no precipitate was generated. In addition, the ink after being left standing was subjected to a printing test using a commercially available jet printer (Deskjet 500J manufactured by Yokogawa-Hewlett-Packard Co., Ltd.), and good printing quality was obtained without nozzle clogging. .

Example 2 Compound of Example 3 0.3% C.I. I. Direct Yellow 44 2.0% Diethylene glycol 25.0% Triethanolamine 0.4% Ion-exchanged water 72.3%

The above components were mixed and sufficiently dissolved at room temperature, and then filtered through a 0.45 micron membrane filter to obtain an aqueous ink for ink jet recording.
At this time, the pH of the ink was 6.9 at 25 ° C.
The pH of the ink in which the compound of Example 3 was omitted from the above composition was 9.8.

The obtained ink was filled in a Teflon container and 6
There was no change in the physical properties of the ink even after standing for 1 month at 0 ° C. and 5 ° C., and no precipitate was generated. In addition, the ink after being left standing was subjected to a printing test using a commercially available jet printer (Deskjet 500J manufactured by Yokogawa-Hewlett-Packard Co., Ltd.), and good printing quality was obtained without nozzle clogging. .

Example 3 Compound of Example 4 0.06% C.I. I. Food Black 2 2.0% Diethylene glycol 20.0% Ion-exchanged water 77.94%

The above components were mixed, sufficiently dissolved at room temperature, and then filtered with a 0.45 micron membrane filter to obtain an aqueous ink for ink jet recording.
The pH of the ink at this time was 3.4 at 25 ° C.
The pH of the ink obtained by omitting the compound of Example 4 from the above composition was 6.2.

The obtained ink was filled in a Teflon container and 6
There was no change in the physical properties of the ink even after standing for 1 month at 0 ° C. and 5 ° C., and no precipitate was generated. In addition, the ink after being left standing was subjected to a printing test using a commercially available jet printer (Deskjet 500J manufactured by Yokogawa-Hewlett-Packard Co., Ltd.), and good printing quality was obtained without nozzle clogging. .

Example 4 Compound of Example 6 0.1% C.I. I. Food Black 2 2.0% Diethylene glycol 20.0% Ion-exchanged water 77.9%

The above components were mixed and sufficiently dissolved at room temperature, and then filtered through a 0.45 micron membrane filter to obtain an aqueous ink for ink jet recording.
The pH of the ink at this time was 3.1 at 25 ° C.
The pH of the ink in which the compound of Example 6 was omitted from the above composition was 6.2.

The obtained ink was filled in a Teflon container and 6
There was no change in the physical properties of the ink even after standing for 1 month at 0 ° C. and 5 ° C., and no precipitate was generated. In addition, the ink after being left standing was subjected to a printing test using a commercially available jet printer (Deskjet 500J manufactured by Yokogawa-Hewlett-Packard Co., Ltd.), and good printing quality was obtained without nozzle clogging. .

Comparative Example 1 0.1N hydrochloric acid 0.5% C.I. I. Direct Yellow 1.5% Diethylene glycol 45.0% "Proxel GXL" 0.1% Ion-exchanged water 52.9%

The above components were mixed and sufficiently dissolved at room temperature, and then filtered through a 0.45 micron membrane filter to obtain an aqueous ink for ink jet recording.
The pH of the ink at this time was 7.5 at 25 ° C.

The obtained ink was tested in the same manner as in Example 1. As a result, a deposit was generated and the printing test could not be performed.

Comparative Example 2 Acetic acid 0.1% C.I. I. Food Black 2 2.0% Diethylene glycol 20.0% Ion-exchanged water 77.9%

The above components were mixed, sufficiently dissolved at room temperature, and then filtered through a 0.45 micron membrane filter to obtain an aqueous ink for ink jet recording.
At this time, the pH of the ink was 3.5 at 25 ° C.

The obtained ink had a strong acetic acid odor, which was a problem in practical use.

[0054]

The water jet ink for jet recording of the present invention comprises:
The pH of the ink can be adjusted without impairing the dissolution stability of the dye.

Claims (2)

[Claims] 1. A water-based inkjet recording ink containing a colorant, a water-soluble organic solvent, and a carboxylic acid having a hydroxyl group. Wherein the carboxylic acid formula having a hydroxyl group (1) ## STR1 ## _{HO- (CH 2 CH 2 O)} n -CH 2 -COOH ( wherein, n represents an integer of 0-5.) in compound and formula (2) ## STR2 ## in _{X-CH 2 -C (Y)} (Z) C m H 2m -COOH ( formula represented, X represents H, OH or COOH, Y is H or Represents OH, Z represents H or COOH, but at least one of X and Y represents OH, and m represents 0 or 1, and at least one selected from the group consisting of compounds represented by The water-based ink for jet recording according to claim 1, which is a compound.