JP3521594B2 - Recording liquid for inkjet - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an inkjet recording liquid having excellent water resistance.

[0002]

2. Description of the Related Art Conventionally, as ink jet recording liquids, water-soluble dyes such as acid dyes, direct dyes and basic dyes are dissolved in a glycol solvent and water (see, for example, JP-A No. 6-58200).
3-61412, JP-A-54-89811, JP-A-55
─65269) is often used. As the water-soluble dye, those having high solubility in water are generally used in order to obtain stability of the recording liquid. Therefore, the ink jet recorded matter generally has poor water resistance, and there is a problem that spillage of water easily causes bleeding of the dye in the recorded portion.

In order to improve such poor water resistance,
Attempts have been made to change the structure of the dye and to prepare a recording liquid having strong basicity (Japanese Patent Laid-Open No. 56-57862). Further, it is also attempted to improve the water resistance by making good use of the reaction between the recording paper and the recording liquid (Japanese Patent Laid-Open No. 50900/50).
4, JP-A-57-36692, JP-A-59-2069
6, JP-A-59-146889). Although these methods have remarkable effects on specific recording papers, they lack versatility in that they are restricted by recording papers, and when a non-specific recording paper is used, a water-soluble dye is used. In many cases, the recording liquid used cannot obtain sufficient water resistance of the recorded matter.

Recording liquids having good water resistance include those in which an oil-soluble dye is dispersed or dissolved in a high boiling point solvent and those in which an oil-soluble dye is dissolved in a volatile solvent. There is a problem of the emission of sewage, which is not environmentally preferable.
Further, there is a problem that solvent recovery or the like is required when a large amount of recording is performed or depending on the installation location of the device. Therefore,
In order to improve the water resistance of a recorded matter, a recording liquid in which a pigment is dispersed in an aqueous medium has been developed. However, in the recording liquid for inkjet, the nozzle diameter is becoming smaller as the printer is required to have higher resolution, and accordingly, it is necessary to make the particle diameter of the coloring agent smaller. Further, in image formation on a transparent substrate such as an overhead projector, transparency as high as a dye is required, and therefore miniaturization is also required from the viewpoint of pigment color development.

In paints and inks, transparency is generally improved by decreasing the particle size of the pigment and increasing the degree of dispersion.
In a conventional disperser such as a sand mill, a three-roll mill or a ball mill, when the primary particles are dispersed, the transparency cannot be further improved. This is because the dispersion process with an ordinary disperser mainly breaks secondary particles (primary particles are weakly agglomerated) into primary particles, and in order to improve transparency further, primary particles are Need to be more detailed. In a high speed sand mill, it is possible to make the primary particles finer depending on the pigment used, but it is difficult to make the primary particles even finer by applying a very large amount of energy.

As another method, there is known a method in which a pigment and a solid resin are heated and kneaded strongly with a two-roll or Banbury mixer. However, since pigments generally undergo crystal growth at high temperatures, this method ends when the mechanical crushing force and crystal growth reach an equilibrium state, and there is a limit to the miniaturization of pigments.

Further, a mixture of a pigment and a water-soluble inorganic salt such as salt is moistened with a small amount of a water-soluble solvent, strongly kneaded with a kneader or the like, and then the inorganic salt and the solvent are washed off with water and dried to obtain a fine pigment. It is known how to get. For example, a method for pigmenting β-type copper phthalocyanine by mechanically grinding crude copper phthalocyanine in the presence of salt and a water-soluble organic solvent is known. Generally, such a method is called salt milling (solvent salt milling).

[0008] The pigment-dispersed recording liquid obtained by this method can eliminate clogging at the nozzles, and in image formation on a transparent device such as an overhead projector, the same level of transparency and clarity as a dye can be obtained. On the recording paper, the dye dyes the recording paper fibers to obtain a clear image, whereas when a pigment dispersion type recording liquid is used, the pigment falls between the fibers and the color of the underlying recording paper is changed. There is a problem that the image cannot be concealed and the sharpness is impaired. This problem has become remarkable with the miniaturization of pigments.

[Problems to be Solved by the Invention]

The present invention solves the above-mentioned problems of the conventional methods, and relates to a water-dispersible ink jet recording liquid which is transparent and has a clear image quality and has good ejection stability at a nozzle.

[Means for solving the problem]

According to the present invention, a particle size of 0.
1 to 100 parts by weight of a fine particle organic pigment having a particle diameter of 0.01 to 0.1 μm and titanium oxide having a particle diameter of 0.01 to 0.1 μm
A recording liquid for ink jet, comprising a dispersion of 500 parts by weight of a colorant, wherein the fine particle organic pigment comprises an organic pigment, a water-soluble inorganic salt in the presence of the fine particle titanium oxide, and It is an inkjet recording liquid which is a fine particle organic pigment obtained by salt milling together with a water-soluble solvent.

Further, the present invention is the above-mentioned ink jet recording liquid, wherein the particle diameter of the fine particle organic pigment is 0.01 to 0.2 μm. Furthermore, the present invention is the above recording liquid for inkjet, wherein the particle size of the fine titanium oxide particles is 0.01 to 0.03 μm. Further, the present invention is the above-mentioned ink jet recording liquid, wherein salt milling is carried out in the presence of a water-soluble solvent and a water-soluble inorganic salt in a weight ratio of 2 to 20 times.

Further, in the present invention, a coloring agent is added to the recording liquid in an amount of 0.1 to 0.1%.
The inkjet recording liquid contains 10% by weight. Further, the present invention provides the above inkjet recording, wherein the organic pigment is at least one selected from the group consisting of quinacridone type, phthalocyanine type, azo type, isoindolinone type, dianthraquinonyl red type, slene type and perylene type. It is a liquid. Further, the present invention is the above-mentioned ink jet recording liquid, which contains an aqueous resin.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention uses an inorganic salt as a grinding aid and a water-soluble solvent in order to obtain transparency and clarity of a water-dispersed inkjet recording liquid and a recorded product using the same. It is a water-dispersed inkjet recording liquid that uses mechanically finely divided primary particles of an organic pigment (hereinafter referred to as salt milling) as a coloring agent. In addition, by using the fine particle titanium oxide in combination, the conventional titanium oxide (average primary particle diameter 0.3 μm) can be added to the ink, and can be stably used in the water-dispersible inkjet recording liquid even when used in combination with salt milling. We were able to solve the problems that titanium oxide could not exist and that the phenomenon of sedimentation occurred, and the problem of becoming opaque when forming images on transparent equipment such as overhead projectors. Therefore, by using fine particle titanium oxide, the dispersion stability of the water-dispersible inkjet recording liquid over time can be achieved, and transparency is not impaired as compared with the conventional method, and a printed matter excellent in sharpness can be provided. It was successful.

More specifically, regarding the above salt milling method, a small amount of a water-soluble solvent is added to a mixture of an organic pigment, fine particles of titanium oxide and a water-soluble inorganic salt, and the mixture is kneaded with a kneader or the like and then put into water. Then, a water-soluble inorganic salt and a water-soluble solvent are dissolved to form a slurry. Next, the slurry is repeatedly filtered and washed with water to remove the inorganic salt and the solvent. By this method, a fine particle organic pigment containing fine particle titanium oxide can be obtained. By dispersing the thus-obtained pigment dispersion and the aqueous resin with an ordinary disperser such as a sand mill, the pigment is finely dispersed as compared with the case of using an untreated pigment (not subjected to salt milling treatment). Further, the ink jet recording liquid can be easily obtained in a short time without spending a long dispersion time.

The pigment used in the present invention is not particularly limited as long as it does not dissolve in water, but an inorganic pigment having a hardness larger than or not much different from the inorganic salt of the grinding aid generally makes the primary particles of the pigment fine. It is preferable to use an organic pigment which is difficult and has low hardness.

Examples of organic pigments include insoluble azo pigments such as toluidine red, toluidine maroon, Hansa yellow, benzidine yellow, and pyrazolone red, litol red, heliobordeaux, pigment scarlet,
Soluble azo pigments such as permanent red 2B, pigments derived from vat dyes such as alizarin, indanthrene, and thioindigo maroon, phthalocyanine-based pigments such as phthalocyanine blue and phthalocyanine green, quinacridone pigments such as quinacridone magenta, and perylene. Perylene series such as red and perylene scarlet, isoindolinone series such as isoindolinone yellow, isoindolinone orange, and dianthraquinonyl red are used.

Examples of such pigments include the following pigments. It is indicated by the color index (CI) number. CI Pigment Yellow 12, 13, 14, 17, 2
0, 24, 74, 83, 86 93, 109, 110,
117, 125, 137, 138, 147, 148, 1
53, 154, 166, 168, CI Pigment Orange 13, 16, 36, 43, 51, 55, 59, 61,
CI Pigment Red 9, 48, 49, 52, 53, 5
7, 97, 122, 123, 149, 168, 177,
180, 192, 215, 216, 217, 220, 2
23, 224, 226, 227, 228, 238, 24
0, CI pigment violet 19, 23, 29, 3
0, 37, 40, 50, CI Pigment Blue 15, 1
5: 1, 15: 4, 15: 6, 22, 60, 64, CI
Pigment Green 7, 36, CI Pigment Brown 23, 25, 26 and the like can be exemplified.

The fine particle titanium oxide used in the present invention has a particle diameter in the range of 0.01 to 0.1 μm. The particle size is preferably 0.01 to 0.03 μm in which the particle size is fine and the particle size distribution is uniform. In the present invention, the particle size of the fine particle titanium oxide is represented by the particle size obtained by assuming that it is a sphere from the BET specific surface area. The particulate titanium oxide is 1 to 500 with respect to 100 parts by weight of the particulate organic pigment.
Parts by weight, preferably 50 to 300 parts by weight are used. When the amount of treatment is small, the effect of clearness is small when the recording liquid is printed on the recording paper, and when the amount of treatment is large, the dispersion stability of the recording liquid with time is insufficient and the coloring power is further lowered.

Examples of the water-soluble inorganic salt used in the present invention include common salt, potassium chloride, mirabilite and the like. The amount of the water-soluble inorganic salt used is 2 by weight with respect to the water-soluble solvent.
˜20 times, more preferably 3 to 10 times.

The water-soluble solvent used in the present invention is not particularly limited as long as it is water-soluble, but since the temperature rises during salt milling and the solvent is easily evaporated, it has a high boiling point from the viewpoint of safety. Solvents are preferred. A water-soluble solvent is added for the purpose of binding and preventing crystallization. Examples include 2- (methoxymethoxy) ethanol, 2-butoxyethanol, 2- (isopentyloxy) ethanol, 2- (hexyloxy) ethanol, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene. Glycol, triethylene glycol monomethyl ether, liquid polyethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-ethoxy-2-propanol, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol mono Ethyl ether, low molecular weight polypropylene glycol and the like are used. The amount of the water-soluble solvent used is preferably 2 to 10 times the weight of the organic pigment to be treated.

In addition to the above compounds, additives such as a dispersant and a plasticizer may be used together during salt milling, or two or more pigments may be mixed and treated. In the present invention, an aqueous dispersion of an organic pigment that has been subjected to a salt milling treatment as described above is used as a colorant, and after the colorant and an aqueous resin that is a binder resin are dispersed using an aqueous medium, the aqueous dispersion is added to the aqueous medium. And diluted to produce an inkjet recording liquid.

Regarding the particle size of the fine particle organic pigment of the present invention, the average particle size determined by the actual measurement of the particle size by an electron micrograph is 0.5 μm or less, preferably 0.2 μm or less. When the particle size is in this range, the filtering operation in the production of the recording liquid is easy, and the recording liquid is less likely to sediment over time. Further, a surface-treated pigment having a functional group added to the surface of the pigment may be used.

In the present invention, an aqueous resin is used to fix the colorant well. As the water-based resin, a water-soluble resin that dissolves in water or a water-dispersible resin that is dispersed in water is used alone or as a mixture. As such an aqueous resin, a water-soluble resin such as an acrylic resin, a styrene-acrylic resin, a polyester resin, a polyamide resin, or a polyurethane resin which is soluble in water and a resin which is dispersible in water are used.

These resins are contained in the recording liquid in an amount of 0.5-10.
%, Preferably 1-5% by weight. If it is less than 0.5% by weight, the colorant cannot be sufficiently fixed. Also,
If it exceeds 10% by weight, the ejection stability of the recording liquid may be deteriorated.

When a water-soluble resin is used as the water-based resin, the viscosity of the recording liquid tends to be increased, but with a water-dispersible resin, the viscosity can be suppressed to a low level. Water resistance can be improved. To these resins, a neutralizing agent such as ammonia, amine, or inorganic alkali can be appropriately adjusted and added if necessary.

In the present invention, the aqueous solvent used in addition to water prevents the recording liquid from drying at the nozzle portion and solidifying the recording liquid, and prevents stable ejection of the recording liquid and drying of the nozzle over time. It is a thing. As such an aqueous solvent, ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, polyethylene glycol, glycerin, tetraethylene glycol, dipropylene glycol, ketone alcohol, diethylene glycol monobutyl ether, ethylene glycol monobutyl ether ethylene glycol monoethyl ether, 1,2-hexanediol, N-methyl-2
Examples thereof include pyrrolidone, substituted pyrrolidone, 2,4,6-hexanetriol, tetrafurfuryl alcohol, and 4-methoxy-4-methylpentanone. For the purpose of accelerating the drying of the recording liquid on paper, methanol,
Alcohols such as ethanol and isopropyl alcohol can also be used. These aqueous solvents are used alone or as a mixture in the range of 1 to 50% by weight of the recording liquid.
As the medium of the recording liquid, deionized water or distilled water from which metal ions have been removed is used.

When the material to be printed with the recording liquid is like paper,
A penetrant can be added in order to accelerate the permeation of the recording liquid into the paper and the apparent dryness. Such penetrants include glycol ethers such as diethylene glycol monobutyl ether described as aqueous solvents, alkylene glycols, alkylene diols, polyethylene glycol monolauryl ether, sodium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium oleate, dioctyl sulfosuccinic acid. Sodium or the like can be used. These have a sufficient effect when used in an amount of 5% or less of the recording liquid, and if the amount is more than this amount, it causes bleeding of printing and paper missing (print through), which is not preferable.

A fungicide may be added to the recording liquid of the present invention in order to prevent the generation of mold. Specifically, sodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide, zinc pyridinethione-1-oxide, 1,2-benzisothiazoline-3.
An amine salt of 1-one or 1-benzisothiazolin-3-one is used. These are 0.05 to 1.
About 0% by weight is used.

A chelating agent may be added in order to prevent the deposition of metal at the nozzle portion and the insoluble matter in the recording liquid. The chelating agent blocks metal ions in the recording liquid, and specifically, ethylenediaminetetraacetic acid, sodium salt of ethylenediaminetetraacetic acid, diammonium salt of ethylenediaminetetraacetic acid, ethylenediaminetetraacetic acid. An acid tetraammonium salt or the like can be used in an amount of about 0.005 to 0.5% by weight.

In addition, in order to adjust the pH of the recording liquid to a desired pH and to stabilize the recording liquid or the stability with the recording liquid pipe in the recording apparatus, an adjusting agent such as amine, inorganic salt, ammonia, phosphorus, etc. A buffer solution such as an acid can be used. Also,
An antifoaming agent may be added in order to prevent the circulation or movement of the recording liquid or the generation of bubbles during the production of the recording liquid.

In order to improve the dispersion of the pigment, the following surfactants may be added and used. As such a surfactant, an anionic, nonionic, cationic or amphoteric surfactant can be used. Examples of the anionic activator include fatty acid salts, alkyl sulfate ester salts, alkyl aryl sulfonates, alkyl naphthalene sulfonates, dialkyl sulfonates, dialkyl sulfosuccinates, alkyl diaryl ether disulfonates, alkyl phosphates, and polyphosphates. Examples thereof include oxyethylene alkyl ether sulfate, polyoxyethylene alkylaryl ether sulfate, naphthalene sulfonic acid formalin condensate, polyoxyethylene alkyl phosphate ester salt, glycerol borate fatty acid ester, and polyoxyethylene glycerol fatty acid ester.

As the nonionic activator, polyoxyethylene alkyl ether, polyoxyethylene alkylaryl ether, polyoxyethylene oxypropylene block copolymer, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, Examples thereof include glycerin fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkylamine, fluorine-based and silicon-based nonionic activators. Examples of the cationic activator include alkylamine salts, quaternary ammonium salts, alkylpyridinium salts, alkylimidazolium salts and the like. Examples of the zwitterionic activator include alkylbetaine, alkylamine oxide, phosphadylcholine and the like.

The dye may be used in such a form that there is no problem in water resistance and light resistance for the purpose of adjusting the hue of the pigment and imparting the concentration. Depending on the use of the dye, the dispersion stability of the pigment may be impaired.
Hereafter, it is necessary to limit the use to 25% by weight or less. As the dye, disperse dyes, water-insoluble dyes such as oil-soluble dyes, direct dyes, acid dyes, basic dyes and the like insolubilized by lake formation, reactive dyes, metal-containing dyes and the like are used. These dyes are preferably purified dyes from which inorganic salts have been removed.

Specifically, C.I. I. Direct Black 17, 19, 32, 51, 71, 108, 146, 15
4, 166, C.I. I. Add Black 2, 7, 24, 2
6, 31, 52, 63, 112, 118, C.I. I. Basic Black 2, C.I. I. Direct Blue 6, 2
2, 25, 71, 90, 106, C.I. I. Acid Blue 9, 22, 40, 59, 93, 102, 104, 11
3, 117, 120, 167, 229, 234, C.I.
I. Basic Blue 1, 3, 5, 7, 9, 24, 2
5, 26, 28, 29, C.I. I. Direct Red 1,
4, 17, 28, 83, C.I. I. Acid Red 1,
6, 32, 37, 51, 52, 80, 85, 87, 9
2, 94, 115, 180, 256, 315, 317.
C. I. Basic Red 1, 2, 9, 12, 13, 1
4, 37, C.I. I. Direct Yellow 12, 24, 2
6, 98, C.I. I. Acid Yellow 11, 17, 23,
25, 29, 42, 61, 71, C.I. I. Basic Yellow 11, 28. C. I. Direct Orange 34, 3
9, 44, 46, 60, C.I. I. Direct violet 47, 48, C.I. I. Direct Brown 109,
C. I. Direct Green 59, C.I. I. Acid Orange 7, 19, C.I. I. Acid Violet 49,
C. I. Basic violet 7, 14, 27, etc. can be illustrated. Other additives such as urea and dimethylurea may be added.

For the production of the recording liquid, a colorant, a dispersant, water or an aqueous resin, an aqueous solvent and the like are mixed and dispersed by a sand mill, a homogenizer, a ball mill, a paint shaker, an ultrasonic disperser or the like. Alternatively, after thoroughly kneading with a two-roll mill, the mixture is further dispersed with the above sand mill or the like, appropriately diluted with water, and other additives are mixed to produce a recording liquid. The mixing and stirring can be performed by a high-speed dispersing machine, an emulsifying machine or the like, in addition to the stirring with a usual stirrer using blades.

The mixed recording liquid is used before dilution or
Then, it is sufficiently filtered with a filter having a pore size of 3 μm or less. It is preferable to filter with a filter of 1.0 μm or less, and more preferably with a filter of 0.45 μm or less. Prior to the filtration of the filter, it is also possible to remove those with a large particle size by centrifugation, which reduces clogging in the filtration by the filter and prolongs the service life of the filter.

The recording liquid is preferably prepared as a liquid having a viscosity of 0.8 to 15 mPa · s (25 ° C.), though it depends on the type of recording device. Surface tension is 25-60 dyn /
cm is preferable, and the pH is not particularly limited, but is 4 to 12
And a weak alkalinity of 7 to 9 is preferable. The recording liquid produced by the present invention is preferably used as an inkjet recording liquid because it is remarkably good in water resistance while being water-based.
It can be used in the fields of cardboard marking, numbering, recorded materials such as barcodes.

[0038]

EXAMPLES The present invention will be described below based on examples. In the examples, "parts" means "parts by weight". [Example 1] Crude copper phthalocyanine (copper phthalocyanine manufactured by Toyo Ink): 250 parts, sodium chloride: 160
0 part, MT-100S (Taika's average primary particle size of
015 μm fine particle titanium oxide: particle diameter determined assuming that it is a sphere from the specific surface area of BET)): 250 parts, and 200 parts of diethylene glycol (manufactured by Tokyo Kasei) are charged into a stainless steel 1 gallon kneader (manufactured by Inoue Seisakusho), Three
Kneaded for hours. Next, this mixture was poured into 2.5 liters of warm water and heated to about 80 ° C. and stirred. After stirring for about 1 hour to form a slurry, filtration and washing with water were repeated 5 times to remove sodium chloride and the solvent to obtain an aqueous pigment dispersion having a solid content of 50% (treated pigment dispersion). The following raw materials were placed in a sand mill and dispersed for 3 hours to prepare a concentrated recording liquid for inkjet.

Method for producing concentrated recording liquid Blue pigment (treated pigment dispersion, solid content 50% product) 30.0 parts Acrylic resin (John Cryl 61J manufactured by Johnson Polymer, solid content 31.0%) 3.0 parts Dimethylaminoethanol 0 1 part Dispersant (Emulgen 420 manufactured by Kao) 1.0 part Purified water 59.9 parts Glycerin 6.0 parts After dispersion, they were mixed with the following. After mixing, the mixture was filtered with a 1 μm membrane filter and then with a 0.45 μm membrane filter to prepare a recording liquid. Concentrated recording liquid 13.5 parts Dispersant (Emulgen 420 manufactured by Kao) 0.2 parts Acrylic resin (W-215 manufactured by Nippon Polymer) 1.0 part Ethylene glycol 10.0 parts Sodium omazine (manufactured by Aurin) 0.15 parts Ethylenediaminetetra Acetic acid sodium salt 0.02 parts Purified water 75.13 parts

The filterability at the time of obtaining the recording liquid was evaluated, and the viscosity and the average particle diameter of the obtained recording liquid were evaluated as follows, and the jetting characteristics, the printing condition, and the like when the recording liquid was used, The transparency of the recorded matter and the water resistance of the recorded matter were evaluated. The results are shown in Table 1.

[Filtration] 1 mm of diameter 90 mm within a fixed time
Amount that can be filtered with a membrane filter of μm and 0.45 μm. [Viscosity] The viscosity was measured at 25 ° C. using a B type viscometer. [Average Particle Size] The average particle size of the organic pigment particles was determined by an electron micrograph. [Printing State] This recording liquid was put in a cartridge of HG5130 manufactured by Epson and recording was performed on plain paper (K manufactured by Xerox). The printed state (clearness) of the recorded matter was evaluated by both visual evaluation and a color machine (Nippon Denshoku Σ80: indicated by C value of Munsell).

[Ejection characteristics] The ejection state of the nozzle during continuous printing was evaluated by the printed matter. Good: Printing can be performed accurately and continuously at a predetermined position. Defective: Despite continuous printing, a defect occurred in the middle or printing was not performed at a predetermined position. [Water resistance] When recording on plain paper (K, made by Xerox), water drips on the recording surface, or the printed matter is dried and immersed in water for 1 minute. The soup stock was visually evaluated. [Transparency] The transparency when ink was spread on an OHP sheet for inkjet with a 1.5 mil applicator was visually evaluated.

Example 2 In the same manner as in Example 1 except that the crude copper phthalocyanine of Example 1 was replaced with 260 parts of a yellow pigment (Hoster Palm Yellow H3G manufactured by Hoechst: Hansa Yellow), an aqueous dispersion (treated pigment) was used. Dispersion)
Got Then, a concentrated recording liquid for inkjet was prepared in the same manner as in Example 1. An inkjet recording liquid having excellent transparency and clarity was obtained. The evaluation results are shown in Table 1.

Example 3 In place of the crude copper phthalocyanine of Example 1, 250 parts of red pigment (Hoster Palm Pink E: quinacridone type manufactured by Hoechst), MT600
An aqueous dispersion (treated pigment dispersion) was obtained in the same manner as in Example 1 by using 500 parts of B (fine titanium oxide having an average primary particle diameter of 0.05 μm, manufactured by Teika). Then, a concentrated recording liquid for inkjet was prepared in the same manner as in Example 1. An inkjet recording liquid having excellent transparency and clarity was obtained. The evaluation results are shown in Table 1.

Comparative Example 1 The blue pigment, the yellow pigment and the red pigment used in Examples 1, 2 and 3 were subjected to salt milling without titanium oxide fine particles, and the obtained aqueous dispersion was used to perform inkjet recording. A liquid was prepared. This recording liquid was placed in a cartridge of HG5130 manufactured by Epson and recording was performed on plain paper (K manufactured by Xerox). The printed state (clearness) of the recorded matter was evaluated by both visual evaluation and a color machine (Nippon Denshoku Σ80: indicated by C value of Munsell). 1.5% transparency for inkjet OHP sheets
The transparency when the ink was spread with a mill applicator was visually evaluated.

Example 4 In place of the crude copper phthalocyanine of Example 1, 250 parts of a yellow pigment (BASF manufactured Pariotor Yellow D-1819: isoindolinone type),
Sodium chloride: 2500 parts and diethylene glycol 200 parts (manufactured by Tokyo Kasei) were charged into a stainless steel 1 gallon kneader (manufactured by Inoue Seisakusho) and kneaded for 3 hours. Next, this mixture was poured into 2.5 liters of warm water and heated to about 80 ° C.
It was heated up to and stirred. After stirring for about 1 hour to form a slurry, filtration and washing with water were repeated 5 times to remove sodium chloride and the solvent to obtain an aqueous pigment dispersion (treated pigment dispersion) having a solid content of 50%. The following raw materials were placed in a sand mill and dispersed for 3 hours to prepare a concentrated recording liquid for inkjet.

Method for producing concentrated recording liquid Yellow pigment (treated pigment dispersion, solid content 50% product) 30.0 parts Acrylic resin (John Cryl 61J manufactured by Johnson Polymer, solid content 31.0%) 3.0 parts MT-100S ( Fine particles of titanium oxide having an average primary particle diameter of 0.015 μm made by Teika: Particle diameter obtained by assuming that the particles are spheres based on the specific surface area of BET)) 15.0 parts Dimethylaminoethanol 0.1 parts Dispersant (Emulgen manufactured by Kao Corporation) 420) 1.0 part Purified water 44.9 parts Glycerin 6.0 parts After dispersion, they were mixed with the following. After mixing, the mixture was filtered with a 1 μm membrane filter and then with a 0.45 μm membrane filter to prepare a recording liquid.

Concentrated recording liquid 13.5 parts Dispersant (Emulgen 420 manufactured by Kao) 0.2 parts Acrylic resin (W-215 manufactured by Nippon Polymer) 1.0 part Ethylene glycol 10.0 parts Sodium omazine (manufactured by Aurin) 0.15 Parts Ethylenediaminetetraacetic acid sodium salt 0.02 parts Purified water 75.13 parts An inkjet recording liquid excellent in transparency and sharpness was obtained. The evaluation results are shown in Table 1.

[Example 5] Red pigment (CIBA's chromophthal red A-2B: diaminodianthranil type)
240 parts, 1600 parts of sodium chloride and 200 parts of diethylene glycol were charged into a stainless steel 1 gallon kneader and kneaded for 3 hours. This mixture was put into 2.5 liters of warm water together with 250 parts of the particulate titanium oxide used in Example 1, heated to about 80 ° C. and stirred. After about 1 hour to form a slurry, filtration and washing with water were repeated 5 times to remove sodium chloride and the solvent to obtain an aqueous pigment dispersion having a solid content of 50%. Then, a concentrated recording liquid for inkjet was prepared in the same manner as in Example 1. An inkjet recording liquid having excellent transparency and clarity was obtained. The evaluation results are shown in Table 1.

Example 6 An aqueous dispersion was prepared in the same manner as in Example 1 except that 200 parts of a blue pigment (Lionogen Blue 6505: Indanthrene type, manufactured by Toyo Ink Co., Ltd.) was used instead of the crude copper phthalocyanine of Example 1. A body (treated pigment dispersion) was obtained. Then, a concentrated recording liquid for inkjet was prepared in the same manner as in Example 1. An inkjet recording liquid having excellent transparency and clarity was obtained. The evaluation results are shown in Table 1.

Example 6 In the same manner as in Example 1, except that the crude copper phthalocyanine of Example 1 was replaced with 250 parts of a red pigment (Palitor Red L3670 manufactured by CIBA: perylene type), an aqueous dispersion (treated pigment dispersion) was prepared. Got a body). Then, a concentrated recording liquid for inkjet was prepared in the same manner as in Example 1. An inkjet recording liquid having excellent transparency and clarity was obtained. The evaluation results are shown in Table 1.

[0052]

[Table 1]

[0053]

EFFECTS OF THE INVENTION According to the present invention, not only a special recording medium but also various recording media, for example, plain paper, while using water as a medium, particulate titanium oxide is used together during the salt milling operation. Alternatively, by adding after salt milling, it was possible to obtain a recording liquid which gave a recorded product having good sharpness and water resistance without impairing transparency.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuharu Iida 2-3-13 Kyobashi, Chuo-ku, Tokyo Toyo Ink Mfg. Co., Ltd. (56) Reference JP-A-6-287492 (JP, A) JP-A 6-322306 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 11 / 00-11 / 20

Claims (7)

(57) [Claims] 1. A particle size of 0.01 to 0.5 in a medium containing water.
Fine particles of titanium oxide 1 to 500 having a particle diameter of 0.01 to 0.1 μm with respect to 100 parts by weight of fine particles of a 0.5 μm organic pigment.
An ink jet recording liquid , characterized in that a coloring agent consisting of parts by weight is dispersed , wherein
The material is an organic pigment in the presence of the above-mentioned particulate titanium oxide,
Saltomiline with water-soluble inorganic salts and water-soluble solvents
For inkjet, which is a fine particle organic pigment obtained by
Recording liquid. 2. The particle size of the fine-particle organic pigment is from 0.01 to
The ink jet recording liquid according to claim 1, which has a thickness of 0.2 μm. 3. The particle size of the fine titanium oxide particles is 0.01 to.
The inkjet recording liquid according to claim 1 or 2, which has a thickness of 0.03 μm. 4. The ink jet recording liquid according to claim 1, wherein salt milling is carried out in the presence of a water-soluble inorganic salt in a water-soluble solvent in a weight ratio of 2 to 20 times. 5. The inkjet recording liquid according to claim 1, wherein the recording liquid contains 0.1 to 10% by weight of the recording liquid. 6. The organic pigment is at least one selected from the group consisting of a quinacridone type, a phthalocyanine type, an azo type, an isoindolinone type, a dianthraquinonyl red type, a slene type and a perylene type. 5. The ink jet recording liquid according to any one of 5 above. 7. The ink-jet recording liquid according to any one of claims 1 to 6, characterized in that it comprises an aqueous resin.