JP2000072993A - Recording liquid and its preparation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a recording liquid improved in setting density, water resistance, delivery stability, and storage stability by dispersing a water-insoluble colorant in an aq. medium in the presence of an anionic polymer and adding a nonionic additive to the resultant dispersion. SOLUTION: 1-10 wt.%, pref. 3-8 wt.%, water-insoluble colorant (e.g. an org. pigment, an inorg. pigment, a disperse dye, or an oil-soluble dye) is dispersed in an aq. medium in the presence of 3-100 wt.%, pref. 3-50 wt.%, anionic polymer which has a pKa of 3 or lower and of which the max. absorbance in the range of 380-780 nm is 0.05 g-1.l.cm-1 or lower, pref. 0.01 g-1.l.cm-1 or lower. The resultant dispersion is compounded with 0.5-10 wt.%, pref. 1-5 wt.%, nonionic additive having an HLB of 9-17, pref. 10-16, and 5-30 wt.%, pref. 10-20 wt.%, water-soluble org. solvent in such an amt. of the nonionic additive that the ratio of the content of the anionic polymer to that of the nonionic additive is (10/1)-(1/1).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording liquid for an aqueous medium, particularly a recording liquid for ink jet recording or a recording liquid for writing implements.

[0002]

2. Description of the Related Art Conventionally, as a recording liquid for ink jet recording, an aqueous ink in which an acidic dye or a direct dye is dissolved in an aqueous medium, or a solvent-based ink in which an oil-soluble dye is dissolved in an organic solvent has been used. . Since the solvent-based ink uses a solvent, it has a problem in terms of environmental safety, and its use is limited, such as being unsuitable for use in offices and the like. On the other hand, since the water-based ink uses a water-soluble dye, there is a problem that the recorded matter has poor water resistance, particularly when recorded on plain paper. Further, the recorded matter of the ink using these dyes is insufficient in light resistance. The same applies to the recording liquid for writing instruments as well as the ink jet ink. In order to solve the above-mentioned problems, a pigment having excellent water resistance and light fastness is used as a coloring material, and an aqueous dispersion ink in which the pigment is dispersed in an aqueous medium is partially used. However, the conventional pigment-based aqueous dispersion ink has a problem in that the long-term storability and the recording density of the recorded matter are insufficient.

[0003]

SUMMARY OF THE INVENTION The present invention is intended for use in ink jet recording or writing instruments, and has a high print quality and high density recording even when recorded on plain paper.
It is intended to provide an aqueous dispersion ink using an aqueous dispersion ink, which has excellent storage stability, good record fastness such as light fastness and water fastness, and has excellent ejection durability. It is assumed that.

[0004]

Means for Solving the Problems The present inventors have conducted various studies on the improvement of print density, improvement of water resistance, improvement of ejection stability and improvement of storage stability of an aqueous dispersion ink for a recording liquid. After a water-insoluble colorant is subjected to dispersion treatment using an anionic polymer, a recording liquid obtained by a preparation method of adding a nonionic additive has good storage stability and ejection stability, and furthermore, this recording liquid The present invention has been found that a printed matter having a high print density and having no print unevenness can be obtained even when recording is performed on plain paper or recycled paper by using the method. The gist of the present invention resides in a recording liquid prepared by dispersing a water-insoluble colorant in an aqueous medium in the presence of an anionic polymer, and then adding a nonionic additive. .

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
As the anionic polymer used in the present invention, any polymer having an anionic water-soluble group such as carboxylic acid (salt), sulfonic acid (salt), and phosphoric acid (salt) can be used. , PKa is preferably 3 or less,
A copolymer having a hydrophobic group is more preferable in terms of storage stability and ejection stability. Among them, a polymer having a sulfonic acid group is most preferable in terms of ejection stability and dispersibility. Examples of the hydrophobic group in the anionic polymer include a functional group having an aromatic ring such as a phenyl group, a benzyl group, and a naphthyl group, a branched or substituted alkyl group, alkenyl group, or alkynyl group having 4 or more carbon atoms. Is mentioned. Specific examples of the anionic polymer used in the present invention include styrene / acrylic acid copolymer, styrene / acrylic acid / acrylate copolymer, styrene / maleic acid copolymer, and styrene / maleic acid / acryl. Acid ester copolymer, styrene / methacrylic acid copolymer, styrene / methacrylic acid / acrylic acid ester copolymer, styrene /
Maleic acid half ester copolymer, styrene / styrene sulfonic acid (salt copolymer, vinyl naphthalene / maleic acid copolymer, vinyl naphthalene / acrylic acid copolymer, naphthalene sulfonic acid formalin condensate, lignin sulfonic acid, or these And the like.
Above all, the anionic polymer of the present invention is preferably uncolored in order to obtain a printed matter which has a good color tone and does not flow into water. Therefore, the maximum value of the absorbance in the range of 380 to 780 nm is 0.05 g ⁻¹ · l.・ Cm ^-1 or less is preferable,
Those having a ^{value of} 0.01 g ⁻¹ · l · cm ⁻¹ or less are particularly preferred.

[0006] As the nonionic additive used in the present invention, a nonionic additive having an alkylene oxide structure is preferable. Among them, a nonionic additive having an ethylene oxide structure or a propylene oxide structure is preferred for storage stability and printing. It is preferable in terms of concentration, and among them, those having an HLB of 9 to 17 are more preferable. Among them, those having an HLB of 10 to 16 are particularly preferable. Specifically, polyoxyethylene nonyl phenyl ether,
Polyoxyethylene octyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene tridecyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene alkylamine, Aminopolyoxyethylene, sorbitan fatty acid ester,
Examples include polyoxyethylene sorbitan laurate, polyoxyethylene sorbitan palmitate, polyoxyethylene sorbitan stearate, polyoxyethylene sorbitan oleate, naphthol ethylene oxide adduct, bisphenol A ethylene oxide adduct, and oxyethylene oxypropylene block polymer.

In the present invention, the content ratio of the anionic polymer to the nonionic additive in the recording liquid is from 10: 1 to 1: 1.
Is preferable in terms of storage stability and print density, but it is particularly preferably 8: 1 to 2: 1. As the water-insoluble coloring material used in the present invention, organic pigments, inorganic pigments,
Examples thereof include disperse dyes and oil-soluble dyes, and specific examples include the following. Specific examples of the pigment used in the yellow ink include CI Pigment Yellow 1, 2, 3,
12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 9
8, 114, 128, 129, 151, 154 and the like.

Specific examples of pigments used in magenta ink include CI Pigment Red 5, 7, 12, 48.
(Ca), CI48 (Mn), 57 (Ca), 57: 1, 112, 123, 168,
184, 202 and the like. Specific examples of the pigment used for the cyan ink include CI Pigment Blue 1, 2, and
3, 15: 3, 15:34, 16, 22, 60, 4, 60 and the like. In addition to the above, CI Pigment Reds 209, 122, 22
4, 177, 194, CI Pigment Orange 43, CI Bat Violet 3, CI Pigment Violet 19, 2
3, 37, CI Pigment Green 36, 7, CI Pigment Blue 15: 6, 209, etc. can also be used.

As oil-soluble dyes, CI Solvent Yellow 16, 21, 25, 29, 33, 56, 82, 88, 89, 150, 151,
163, CI Solvent Red 24, 27, CI Solvent Blue 14, 25, 38, 48, 67, 68, 70, 132, CI Solvent Black 3, 5, 7, 27, 28, 29, 34, etc. can be used,
Oil yellow 105, 107, Balifast yellow 1101, 1105, Balifast red 1306, Balifast blue 1603, 1607, 2610, Balifast black 18
02, 1807, 3830 (all manufactured by Orient Chemical Co., Ltd.), Aizen Spiron Yellow GRLH, 3RH, Aizen Spiron Blue GNH, 2BNH, BPNH, Aizen Spiron Black MH, GMH (above, manufactured by Hodogaya Chemical Co., Ltd.) ),
Oleosol Blue G, Oleosol Black AR (all produced by Taoka Chemical Industry Co., Ltd.), and Orasol Black RL1 (made by Ciba Geigy). As a disperse dye
CI Disperse Yellow 3, 82, 54, CI Disperse Red 60, 191 and Disperse Vilet 57.

In the present invention, carbon black such as acetylene black, channel black and furnace black can be used. The carbon black that can be used has a DBP oil absorption of usually 60 to 200 ml / 100 g or more, preferably 90 ml / 100 g or more, and particularly preferably 140 ml / 100 g or more. The volatile content is usually preferably in the range of 8% by weight or less, and particularly preferably 3% by weight or less. BE
The T specific surface area is preferably at least 150 m ² / g,
Those of ² / ^{g~1000m 2} / g is particularly preferred. The primary particle diameter is preferably 40 nm or less.
nm or less is particularly preferred. Here, the DBP oil absorption of carbon black is a value measured by JIS K6221A method, the volatile content is a value measured by JIS K6221 method, and the primary particle diameter is an arithmetic mean diameter by an electron microscope.

As the above carbon black, # 2
600, # 2300, # 990, # 980, # 960, # 950, # 900, # 850,
# 750, # 650, MCF-88, MA-600, # 95, # 55, # 52, # 47
, # 45, # 45L, # 44, # 40, # 33, # 32, # 30, # 25
, # 20, # 10, # 5 (Mitsubishi Chemical), Color Black
FW1, FW2, FW2V, FW18, FW200, Special Blaek4, 4
A, 5, 6, 100, 250, 350, 550, S160, S170, Pri
ntex U, V, 140U, 140V, 95, 90, 85, 80, 75, 45, 4
0, P, 60, 300, 30, 35, 25, 200, A, G, L6, L
(Made by Degussa), Regal415R, 330R, 250R, 995
R, Monarch800, 880, 900, 460, 280, 120 (or higher,
Cabot), Raven 850, 780ULTRA, 760ULTRA, 79
0 ULTRA, 520, 500, 410, 420, 430, 450, 460,
890, 1020 (all made in Colombia) and the like are specific examples. In the present invention, among the water-insoluble dyes described above, carbon black is particularly preferable.

As the water-insoluble coloring material used in the recording liquid of the present invention, if it has the above physical properties, the water-insoluble coloring material is chemically treated (oxidation treatment, fluorination treatment, etc.). Alternatively, a material in which a dispersant, a surfactant, and the like are physically or chemically bonded (grafting treatment, a material in which a dispersant is previously adsorbed before dispersion, or the like) may be used. In the recording liquid of the present invention, other additives such as a surface tension adjusting agent and a preservative may be used. Examples of additives that can be used include various anionic surfactants, nonionic surfactants different from the nonionic additives of the present invention, cationic surfactants, amphoteric surfactants, and polymeric dispersants. And the like.

Examples of the anionic surfactant include fatty acid salts, alkyl sulfate salts, alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkyl sulfosuccinates, alkyl diphenyl ether disulfonates, alkyl phosphates, and polyoxyethylene alkyl. Sulfate, polyoxyethylene alkylaryl sulfate, alkane sulfonate, naphthalene sulfonic acid formalin condensate, polyoxyethylene alkyl phosphate, α-olefin sulfonate and the like.

The nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl aryl ethers, polyoxyethylene derivatives, oxyethylene, oxypropylene block copolymers, sorbitan fatty acid esters, polyoxyethylene sorbitan Examples include fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, polyoxyethylene fatty acid esters, and polyoxyethylene alkylamines.

Examples of the cationic surfactant and the amphoteric surfactant include alkylamine salts, quaternary ammonium salts, alkyl betaines, and amino oxides. As the polymer dispersant, polyacrylic acid, styrene / acrylic acid copolymer, styrene / acrylic acid /
Acrylic ester copolymer, styrene / maleic acid copolymer, styrene / maleic acid / acrylic ester copolymer, styrene / methacrylic acid copolymer, styrene /
Methacrylic acid / acrylic acid ester copolymer, styrene / maleic acid half ester copolymer, styrene / styrene sulfonic acid copolymer, vinyl naphthalene / maleic acid copolymer, vinyl naphthalene / acrylic acid copolymer or salts thereof And the like. Among them, anionic surfactants, cationic surfactants and polymer dispersants are particularly excellent.

The aqueous medium used in the recording liquid of the present invention is mainly composed of water, but it is preferable to add a water-soluble organic solvent to water. Examples of the water-soluble organic solvent include ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol (# 200, # 400), glycerin, alkyl ethers of the above glycols, N-methylpyrrolidone, 1,3- Examples include dimethylimidazolinone, thiodiglycol, 2-pyrrolidone, sulfolane, dimethylsulfoxide, diethanolamine, triethanolamine, methanol, ethanol, isopropanol and the like.

[0017] In addition to the above components, a water-soluble resin, a fungicide, a bactericide, a pH adjuster, urea, and the like may be added to the recording liquid of the present invention as needed. The recording liquid of the present invention is obtained by mixing a water-insoluble coloring material and an anionic polymer in an aqueous medium, grinding the water-insoluble coloring material into fine particles using a disperser, and dispersing the fine particles into a nonionic additive. It is prepared by adding It is not clear why the preparation method of the present invention improves the performance of the recording liquid, but it is difficult to disperse the water-insoluble colorant under the condition that the anionic polymer and the nonionic additive are simultaneously present as in the conventional case. When the treatment is performed, the adsorption of the anionic polymer to the water-insoluble dye is hindered by the nonionic additive, and a charge double layer is hardly formed around the water-insoluble colorant. It is considered that the dispersion stability of the material was impaired. As a dispersing machine, in addition to a ball mill, a roll mill and a sand grind mill, a jet mill such as a nanomizer and an optimizer that can be pulverized without using a medium is used. In particular, a sand grind mill or a jet mill with less contamination derived from the medium is used. Is preferred. After this grinding and dispersion treatment, coarse particles are removed using a filter or a centrifuge. In addition, since the grinding and dispersion treatment can be efficiently performed by adjusting the concentration of the recording liquid, it is preferable to dilute the processing liquid prepared at a high concentration with an aqueous medium to adjust the concentration of the recording liquid.

The amount of the water-insoluble colorant used is preferably in the range of 1 to 10% by weight based on the total weight of the recording liquid, but is preferably 3 to 8% by weight. The amount of the anionic polymer used is in the range of 3 to 100% by weight based on the weight of the water-insoluble colorant, but is preferably 3 to 50% by weight. The amount of the nonionic additive used is preferably 0.5 to 10% by weight, more preferably 1 to 5% by weight, based on the weight of the water-insoluble colorant. The amount of the water-soluble organic solvent used in the recording liquid is in the range of 5 to 30% by weight, and preferably 10 to 20% by weight in terms of storage stability.

These water-insoluble colorants, dispersants, additives and organic solvents may be used alone, but may be used in combination of two or more in some cases to further improve the effect. Can be given. The recording liquid prepared by the method of the present invention has better performance in storage stability than conventional recording liquids, and the fluctuation in the particle size distribution of the recording liquid when stored at a high temperature for a long time is small. Has features. Specifically, a comparison was made between the particle size distribution measured immediately after preparing the recording liquid and the particle size distribution measured after storing the recording liquid at 70 ° C. for one week, and the difference was calculated for each fraction of the measured particle diameter. Is 15% even if measurement errors are taken into account.
Hereinafter, it is possible to provide a recording liquid that is preferably in the range of 1 to 10%. If this total is too small, coagulation on the recording paper when recording is poor,
This is not preferable because the print density becomes poor. The specific method of measuring the particle size distribution is shown in the examples.

[0020]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which, however, are not intended to limit the scope of the invention. In the following examples, “parts” and “%” are based on weight. Example 1 (Preparation of recording liquid)

[0021]

TABLE 1 Composition of recording liquid Amount used (parts) Carbon black (A) 4 Styrene / ethyl sulfonate Acrylic ester copolymer Na salt 0.4 (Molar ratio = 7/3, weight average molecular weight (Mw) = 4300) ) N-methylpyrrolidone 4 ion-exchanged water 13.4 ─────────────────────────────── total 44

Each of the above components was placed in a cylindrical stainless steel container, and subjected to a dispersion treatment for 40 hours using a sand grinder together with 67 parts of glass beads having an average diameter of 0.5 mm.
The resulting solution was mixed with Olfin E1010 (Shin-Etsu Chemical sales product, acetylene glycol ethylene oxide adduct, H
LB: 13) 0.1 part and 5 parts of ion-exchanged water were added and stirred well, and then 4 parts of glycerin, 3 parts of ethanol and 43.9 parts of ion-exchanged water were further added. This solution was Pressure filtration was performed using a 5C filter paper, and the liquid obtained here was used as a recording liquid. (Printing test) Using the recording liquid obtained by the method described in the above example, ink jet recording was performed under the following conditions. Equipment and equipment used

[0023]

[Table 2] Printer: Hewlett-Packard D
eskWriter660C Ink cartridge: HP51629A Computer: Macintosh Perform
a550 Soft: MacDraw II 1.1

The recording liquid obtained by the method described in the above example was washed with a washed Hewlett-Packard DeskW.
black cartridge for HP writer 660C (HP51
629A) and set in a printer. A black solid of 5 cm × 5 cm was prepared on the above-mentioned Mac draw, and this was electrophotographic paper (Xerox 4024) under the following conditions.
Paper, Xerox products).

[0025]

[Table 3] Print options: Print in monochrome Paper settings Paper size: A4, Paper: Plain paper Options Density setting: Normal, Ink control: Auto, Halftone: Auto, Color preparation: Auto Print Quality: Normal

As a result, a stable and good ejection property without clogging or the like was exhibited, and a printed matter having good print quality was obtained. (Evaluation of Print Density) The density of the printed matter obtained in the above print test was measured using a Macbeth reflection densitometer (RD914).
The results were classified as follows and are shown in Table 1 below.

[0027]

[Table 4] ◎ ────OD1.4 or more ○ ────OD1.3 or more and less than 1.4 △ ────OD1.2 or more and less than 1.3 × ────OD less than 1.2

(Water Resistance Test) The printed matter obtained in the printing test was immersed in tap water taken in a beaker for 5 seconds. After drying the printed matter,
The presence or absence of character stain was visually evaluated. The results were classified as follows and are shown in Table 1 below.

[0029]

[Table 5] ○ ──── almost no dirt △ ──── slight dirt but no problem in practical use × ──── severe dirt

(Light fastness test) The printed matter was irradiated with a xenon fade meter (manufactured by Suga Test Instruments Co., Ltd.) for 100 hours to visually evaluate the discoloration and discoloration. The results were classified as follows and are shown in Table 1 below.

[0031]

[Table 6] ○ △ good △ △ discoloration, but practically no problem × △ discoloration is severe

(Measurement of particle size distribution) The obtained recording liquid is used as it is in a particle size distribution meter (MicrotracUPA (Nikkiso sales)).
The particle size distribution was measured.

[0033]

[Table 7] Measurement conditions Transparent Particles: No, Spherical Particles:
No, Particle Refractive Index: 1.81 Particle Density: 1.86 Fluid Refractive Index: 1.33 High Temp: 30.0 ℃ Viscosity: 0.797 cP Low Temp: 20.0 ℃ Viscosity: 1.002 cP Run Time: 300 (sec), Number of Runs: 2

The average value of the two measurements under the above measurement conditions was taken as the value of the particle size distribution of the recording liquid. (Storage stability test) The obtained recording solution was stored at 70 ° C. for 1 week, and after returning to room temperature after storage, the particle size was measured with a particle size distribution analyzer (MicrotracUPA (Nikkiso sales)) in the same manner as described above. A distribution measurement was performed. The obtained result was compared with the result of the particle size distribution measurement test, and the difference was measured for each fraction of the measured particle size, and the total was calculated. The results are shown in Table 1 below. Example 2 (Preparation of recording liquid)

[0035]

Table 8 Composition of recording liquid Amount used (parts) Carbon black FW18 (manufactured by Degussa) 4 Styrene / ethyl sulfonate acrylate copolymer Na salt 0.6 (molar ratio = 7/3, weight average molecular weight (Mw)) = 4300) 1,3-dimethylimidazolidinone 4 ion-exchanged water 13.4 合計 total 44

Each of the above components was placed in a cylindrical stainless steel container and subjected to a dispersion treatment for 40 hours using a sand grinder together with 67 parts of glass beads having an average diameter of 0.5 mm.
Surfynol 485 (Shin-Etsu Chemical sales product,
Acetylene glycol ethylene oxide adduct, HL
B: 17) After 0.1 part and 5 parts of ion-exchanged water were added and stirred well, 4 parts of glycerin, 3 parts of ethanol and 43.9 parts of ion-exchanged water were further added. This solution was Pressure filtration was performed using a 5C filter paper, and the liquid obtained here was used as a recording liquid. The same evaluation as in the above example was performed using the obtained recording liquid. The results are shown in Table 1 below.

[0037]

[Table 9] Table 2 below shows the physical properties of carbon black used in Examples 1 and 2.

[0038]

[Table 10] * FC: Furnace Carbon Black CC: Channel Carbon Black

[0039]

When the recording liquid of the present invention is used, a stable recorded image having a high recording density and no printing unevenness can be obtained even when ink-jet recording is performed on plain paper or recycled paper.
In addition, a recording liquid having good storage stability and discharge stability can be obtained, and a recorded matter having good image fastness such as water resistance and light resistance can be obtained. Since the present invention has the above characteristics, it can be used as a recording liquid for other purposes, not limited to ink jet and writing instruments.

Claims (7)

[Claims] 1. A recording liquid prepared by dispersing a water-insoluble colorant in an aqueous medium in the presence of an anionic polymer and then adding a nonionic additive. 2. The cumulative difference between the particle size distribution immediately after preparation of the recording liquid and the particle size distribution after storing the recording liquid at 70 ° C. for one week is 1
2. The recording liquid according to claim 1, which is at most 5%. 3. The recording liquid according to claim 1, wherein the nonionic additive has an HLB of 9 to 17. 4. The recording liquid according to claim 1, wherein a polymer having a sulfonic acid (salt) group as an anionic group is used. 5. The recording liquid according to claim 1, wherein the content ratio of the anionic polymer to the nonionic additive is from 10: 1 to 1: 1. 6. The recording liquid according to claim 1, wherein the water-insoluble colorant is carbon black. 7. A method for preparing a recording liquid, comprising dispersing a water-insoluble colorant in an aqueous medium in the presence of an anionic polymer, and then adding a nonionic additive.