JP3141792B2 - Inkjet recording liquid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording liquid having excellent dispersion stability and good nozzle ejection stability.

[0002]

2. Description of the Related Art Conventionally, ink jet recording liquids have been disclosed in JP-A-53-61412 and JP-A-54-89.
As disclosed in JP-A-811 and JP-A-55-65269, those obtained by dissolving a water-soluble dye such as an acid dye, a direct dye or a basic dye in a glycol solvent and water are often used. . However, as the water-soluble dye, a dye having high solubility in water is generally used in order to obtain the stability of the recording liquid, and the ink-jet recorded matter has poor water resistance and is easily recorded when water is spilled. There was a problem that bleeding of some dyes occurred.

In order to improve such poor water resistance,
As disclosed in JP-A-56-57862, attempts have been made to change the structure of a dye or to prepare a recording solution having a strong basicity. Also, Japanese Patent Laid-Open No. 50-490
No. 04, JP-A-57-36692, JP-A-57-36692.
As disclosed in Japanese Patent Application Laid-Open No. 9-20696 and Japanese Patent Application Laid-Open No. Sho 59-146889, improvement of water resistance has also been attempted by making good use of the reaction between recording paper and a recording liquid. Although these methods have a remarkable effect on specific recording paper, they lack versatility in that they are restricted by recording paper, and use water-soluble dyes when other than specific recording paper is used. In many cases, the recording liquid cannot provide sufficient water resistance of the recorded matter.

As recording liquids having good water resistance, there are 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 emission of water, which is environmentally unfavorable.
In addition, there is a problem that solvent recovery or the like is required depending on a case where a large amount of recording is performed or where the apparatus is installed. Therefore, in order to improve the water resistance of the recorded matter, a recording liquid in which a pigment is dispersed in an aqueous medium has been developed.

However, it is very difficult to disperse pigments as fine particles unlike dyes and to keep the dispersion state stable. On the other hand, in the recording liquid for ink jet, the nozzle diameter is becoming narrower as the resolution of the printer is increased, and accordingly, the particle diameter of the pigment needs to be made finer. Further, there is a demand for transparency on a par with dyes in forming an image on a transparent base material such as an overhead projector, and miniaturization is also demanded from the viewpoint of pigment coloring.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to provide an aqueous ink jet recording liquid having stable dispersibility and good ejection stability at a nozzle. It is in.

[0007]

Means for Solving the Problems The inventors of the present invention have proposed an ink jet recording liquid in which an organic pigment is dispersed in an aqueous liquid, after dispersing it in a solvent having no reactivity with sulfonic acid, It has been found that by using a treated pigment treated with an agent, an aqueous inkjet recording liquid having stable dispersibility and excellent ejection stability at a nozzle can be obtained, and the present invention has been accomplished. The treated pigment obtained by treating the surface of an organic pigment with a sulfonating agent is considered to have sulfonic acid groups on the surface of the pigment particles, and the dispersibility in water is improved by the function of the treated pigment surface. Miniaturization becomes possible.

That is, the present invention provides an ink jet recording liquid comprising an organic pigment dispersed in an aqueous liquid,
Organic pigment, an organic pigment dispersed in a solvent having no reactivity with sulfonic acid, sulfonated pyridine salt after accordingly or
Or a sulfonating agent selected from sulfamic acid.
The present invention relates to a recording liquid for inkjet, which is a treated pigment in which a sulfonic acid group is introduced on the surface of the organic pigment .

The organic pigments used in the present invention include toluidine red, toluidine maroon, Hansa Yellow,
Insoluble azo pigments such as benzidine yellow and pyrazolone red; soluble azo pigments such as litol red, helio bordeaux, pigment scarlet and permanent red 2B; derivatives from vat dyes such as alizarin, indanthrone, and thioindigo maroon; phthalocyanine blue; Phthalocyanine pigments such as phthalocyanine green; quinacridone pigments such as quinacridone red and quinacridone magenta; perylene pigments such as perylene red and perylene scarlet; isoindolinone pigments such as isoindolinone yellow and isoindolinone orange; Pyranthrone-based pigments such as red and pyranthrone orange, thioindigo-based pigments, condensed azo-based pigments, benzimidazolone-based pigments, flavanthrone yellow, acylamidoe Over, quinophthalone yellow, nickel azo yellow, copper Azomechin'ero, perinone orange, Anse Ron orange, Dianthraquinonyl Red,
Dioxazine violet and the like can be exemplified.

[0010] Among them, the use of at least one organic pigment selected from the group consisting of quinacridone pigments, phthalocyanine pigments, benzimidazolone pigments, isoindolinone pigments and quinophthalone pigments is advantageous in terms of light resistance and the like. Is preferred. The organic pigment preferably has fine particles, and preferably has an average particle diameter of 10 to 150 nm (measured by a laser scattering method).

The solvent having no reactivity with sulfonic acid used in the present invention is a solvent in which the organic pigment is insoluble or hardly soluble, and has no active proton, especially N-methyl-2-pyrrolidone. Or sulfolane is preferred. Solvents having no reactivity with sulfonic acid maintain the wetting of the organic pigment by the solvent and the state in which the organic pigment is unraveled. It is preferable to use it by weight. If the amount of the solvent is less than 3% by weight of the organic pigment, there is a high possibility that the organic pigment is treated in an aggregated state, and it is difficult to obtain fine particles. On the other hand, if the amount is more than 200 times by weight, the reactivity of the sulfonating agent is adversely affected, and the subsequent solvent removal and washing treatments are large, making the pigment recovery process difficult. In addition, the substantial processing amount of the organic pigment is reduced.

The sulfonating agent used in the present invention includes
Sulfonated pyridine salt or sulfamic acid is used
You . The sulfonating agents can be used alone or in combination of two or more. The treatment with a sulfonating agent involves dispersing the organic pigment in a solvent having no reactivity with sulfonic acid, adding the sulfonating agent and heating to 60 to 200 ° C, or heating to 60 to 200 ° C and then sulfonating. This is done by adding the agent and stirring for 0.5 to 5 hours. Stirring may be performed in advance by high-speed stirring with a high-speed mixer or the like to form a slurry, and then transition to gentle stirring, or heat treatment may be performed while continuing high-speed stirring. Also,
High-speed stirring may be performed only after the heat treatment.

After the heat treatment, the solvent having no reactivity with sulfonic acid and the remaining sulfonating agent are removed from the pigment slurry. Removal is carried out by repeating washing, ultrafiltration, reverse osmosis, etc., centrifugation, filtration and the like. The average particle size of the treated pigment measured by the laser scattering method is 10
It is preferably from 150 to 150 nm, more preferably from 10 to 100 nm. When a treated pigment having such a particle size is used, the filtering operation in the production of the recording liquid is easy, and the sedimentation of the pigment over time is small when the recording liquid is stored. The treated pigment is
The solid content in 100 parts by weight of the recording liquid for ink jet is 0.1%.
It is preferable from the viewpoint of dispersibility that the amount is contained in the range of 1 to 10 parts by weight.

The treated pigment subjected to the sulfonation treatment is 10
An aqueous pigment dispersion can be easily obtained by adding it to an aqueous liquid so as to have a concentration of about 40% by weight or by performing normal dispersion for a short time without passing through a pigment drying step. Can be. Since this aqueous pigment dispersion is a dispersion of treated pigment fine particles showing good dispersibility without adding a dispersant, it is simply diluted to a concentration suitable for printing.
If necessary, an additive can be added and filtered to obtain an ink jet recording liquid. However, the ink is dispersed with a dispersing machine using a dispersant or the like to obtain a stable and highly fixable ink jet recording liquid. Is preferred. When the dispersion is further carried out using a usual dispersing machine such as a sand mill, the ink jet recording liquid in which the pigment is fine and in a stable dispersion state can be easily obtained in a short time without significantly increasing the dispersion time.

For the production of an ink jet recording liquid, a sand mill, a homogenizer, a ball mill, a paint shaker, an ultrasonic disperser. A disperser or the like that disperses by a cavitation effect in a high-pressure room can be used. Also,
Mixing and stirring can be performed by a high-speed disperser, emulsifier, or the like, in addition to stirring by a stirrer using a normal blade.

The ink jet recording liquid of the present invention is preferably sufficiently filtered through a filter having a pore size of 3 μm or less, preferably a filter having a pore size of 1.0 μm or less, and more preferably a filter having a pore size of 0.45 μm or less. Prior to filtration of the filter, it is also possible to remove those having a large particle size by centrifugation, thereby reducing clogging in the filtration by the filter and prolonging the service life of the filter.

As the aqueous liquid, water and, if necessary, an aqueous solvent can be used. As the water, ion-exchanged water or distilled water from which metal ions and the like have been removed can be used, and the water is preferably contained in the recording liquid in a range of 50 to 98% by weight. The aqueous solvent prevents drying and solidification of the recording liquid at the nozzle portion, stably sprays the recording liquid, and also functions as a humectant. It is preferable to use within the range.

As the 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,
Examples include ethylene glycol monoethyl ether, 1,2-hexanediol, N-methyl-2-pyrrolidone, substituted pyrrolidone, 2,4,6-hexanetriol, tetrafurfuryl alcohol, and 4-methoxy-4-methylpentanone. . Further, alcohols such as methanol, ethanol and isopropyl alcohol can be used for the purpose of speeding up drying of the recording liquid.

The ink jet recording liquid of the present invention preferably contains an aqueous resin in order to strengthen the fixability to a printing medium. The aqueous resin also contributes to the dispersibility of the treated pigment. If the printing medium has ink acceptability,
No aqueous resin is required. As the aqueous resin, a water-soluble resin that dissolves in water, a water-dispersible emulsion resin that disperses in water, and a colloidal dispersion resin are used alone or in combination. Specific examples of the water-based resin include water-soluble resins and water-dispersible resins such as acrylic, styrene-acryl, polyester, polyamide, polyurethane, and fluorine.

For the purpose of fixing to a printing medium, the aqueous resin is preferably used in the recording liquid in the range of 0.1 to 10% by weight. If less than this amount,
The pigment cannot be fixed firmly. On the other hand, if the amount is larger than this amount, the viscosity of the recording liquid will increase too much or the ejection stability will decrease. When a water-soluble resin is used as the water-based resin, the viscosity of the recording liquid tends to be high, but the viscosity of the water-dispersible resin can be reduced or the water resistance of the recorded matter can be reduced. It can be further improved. When an aqueous resin is used, it is preferable to add a neutralizing agent such as ammonia, an amine or an inorganic alkali to adjust the dissolution or dispersion stability of the aqueous resin.

The ink-jet recording liquid of the present invention contains a dispersant, a surface tension, an agent for controlling penetration, a fungicide, a chelating agent,
Additives such as an antifoaming agent can be blended as required.
The dispersant can be used to maintain stable dispersion of the pigment, or when the aqueous resin cannot be used for the dispersant, or for more stable dispersion.
Anionic, nonionic, cationic, or zwitterionic activators can be used as the dispersant.

Examples of the anionic activator include fatty acid salts, alkyl sulfate salts, alkyl aryl sulfonates, alkyl naphthalene sulfonates, dialkyl sulfonates, dialkyl sulfosuccinates, alkyl diaryl ether disulfonates, and alkyl phosphoric acids. Salt, polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl aryl ether sulfate, naphthalenesulfonic acid formalin condensate, polyoxyethylene alkyl phosphate ester salt, glycerol borate fatty acid ester, polyoxyethylene glycerol fatty acid ester, etc. Can be illustrated.

Examples of the nonionic activator include polyoxyethylene alkyl ether, polyoxyethylene alkyl aryl 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 an alkylamine salt, a quaternary ammonium salt, an alkylpyridinium salt, an alkylimidazolium salt and the like. Examples of amphoteric surfactants include alkyl betaines, alkylamine oxides, phosphadylcholines, and the like.

When the recording liquid is permeable to the printing medium like paper, a penetrant can be added to stop the penetration of the recording liquid and speed up the apparent dryness. Examples of such penetrants include glycol ethers such as diethylene glycol monobutyl ether as exemplified as aqueous solvents, alkylene glycols, alkylene diols, polyethylene glycol monolauryl ether, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium oleate, dioctyl sulfosuccinic acid. Sodium or the like can be used. The penetrant has a sufficient effect when used in an amount of 5% by weight or less of the recording liquid, and if it is more than 5% by weight, print bleeding and paper loss (print-through) occur, which is not preferable.

A fungicide can be added to prevent the generation of mold and bacteria in the recording liquid. As an antifungal agent,
Sodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide, zinc pyridinethione-1-oxide, 1,2-benzisothiazolin-3-one, amine salt of 1-benzisothiazolin-3-one and the like are used. Can be These are 0.05% in the recording solution.
It is preferably contained in the range of 1.0 to 1.0% by weight.

The chelating agent blocks metal ions in the recording liquid, and can be added to prevent deposition of metal at the nozzle portion, precipitation of insoluble substances in the recording liquid, and the like. Examples of the chelating agent include ethylenediaminetetraacetic acid, sodium salts of ethylenediaminetetraacetic acid, diammonium salts of ethylenediaminetetraacetic acid, and tetraammonium salts of ethylenediaminetetraacetic acid. These are contained in the recording liquid in an amount of from 0.005 to 0.
Preferably, it is contained in the range of 5% by weight.

Further, in order to adjust the pH of the recording liquid and obtain stability of the recording liquid or stability with the recording liquid piping in the recording apparatus, a pH adjuster such as an amine, an inorganic salt or ammonia, and a buffer such as phosphoric acid. Liquids can be used. Further, an antifoaming agent can be added to prevent the recording liquid from being circulated or moved in the discharge or inside the pipe, or from generating bubbles during the production of the recording liquid. Further, for the purpose of adjusting the hue of the pigment, imparting a concentration, and the like, a dye can be used in such a manner that there is no problem in water resistance and light resistance. Depending on the use of the dye, the dispersion stability of the pigment may be deteriorated. Therefore, it is necessary to limit the use of the pigment to 40% by weight or less, preferably 25% by weight or less.

Examples of the dye include water-insoluble dyes such as disperse dyes and oil-soluble dyes, direct dyes, acid dyes, basic dyes, and the like, which are made insoluble by lake formation, reactive dyes, metal-containing dyes, and the like. Purified dyes from which salts have been removed are preferred. Specific examples of the dye include C.I. I. Direct Black 17, 19, 32, 51, 71, 108, 146, 1
54, 166, C.I. I. Add Black 2,7,24,
26, 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 and the like can be exemplified. Urea, dimethyl urea and the like can be added as other additives.

The recording liquid is preferably adjusted as a liquid having a viscosity of 0.8 to 15 centipoise (25 ° C.), depending on the type of the recording apparatus. The surface tension of the recording liquid is 25-60
dyn / cm is preferable, and the pH is not particularly limited.
To 12 from the dispersion stability of the treated pigment.
An alkalinity of 10 is preferred.

Hereinafter, the present invention will be described with reference to examples. In the examples, parts and% indicate parts by weight and% by weight, respectively. (Process Examples 1 to 8 of Organic Pigment) Under the conditions shown in Table 1, the organic pigment was treated as follows. After the organic pigment was dispersed in the solvent and heated, the sulfonating agent was added and maintained with stirring. Then, after washing several times with a solvent, the mixture was poured into water and washed again with water, and an aqueous dispersion (solid content: 15%) of the treated pigment was obtained with a filter.

[0032]

[Table 1]

* 1 Copper phthalocyanine blue * 2 Dimethylquinacridone * 3 Quinophthalone * 4 N-methyl-2-pyrrolidone

(Synthesis example of water-based resin) According to the synthesis method of acrylic resin, methyl methacrylate (MMA), ethyl acrylate (EA), and methacrylic acid (MAA) were copolymerized with the following monomer composition (molar ratio), A copolymer was synthesized. MMA EA MAA molecular weight Synthesis Example 1 10.5 0.5 10000 2 1 1.0 2.0 20,000 3 12.0 1.0 20,000 4 1 2.0 3.0 25000 5 1 3.0 1.0 28000 6 1 3.0 0.5 18000

(Examples 1 to 12) The raw materials shown in Table 2 were charged into a sand mill at the compounding ratio (weight ratio) shown in Table 2, and
Dispersion was performed for ~ 4 hours. After a while, 10,000 rpm
m, and the mixture was filtered through a 0.45 μ filter to prepare an inkjet recording liquid.

[0036]

[Table 2]

Dispersant 1 Nonionic activator "Emulgen 420" manufactured by Kao Corporation Dispersant 2 Nonionic activator "Emulgen A-9" manufactured by Kao Corporation
0 "Dispersant 3 Nonionic dispersant" SOLSPERS
27000 "Acrylic resin 1 Acrylic resin emulsion" W-251 "manufactured by Nippon Polymer Co., Ltd. 40% solid content Acrylic resin 2 Acrylic resin emulsion" Emapoly TYN-50 "manufactured by Gifu Shellac, 44% solid content Acrylic resin 3 Acrylic resin manufactured by Johnson Polymer Aqueous resin solution “Johncryl 62”, solid content 31% Acrylic resin 4 Acrylic resin aqueous solution “Johncryl 61J” manufactured by Johnson Polymer, solid content 31%

Neutralizer 1 Dimethylaminoethanol Neutralizer 2 Diethylaminoethanol Neutralizer 3 Monoethanolamine Wetting agent 1 Glycerin Wetting agent 2 Ethylene glycol Solvent 1 Isopropyl alcohol Solvent 2 Ethyl alcohol Solvent 3 N-methyl-2-pyrrolidone Fungicide 1 "Proxel GXL" manufactured by Zeneca Corp. Antifungal 2 "Sodium Omazine" manufactured by Ohlin Chelating agent Sodium ethylenediaminetetraacetic acid

The recording liquid obtained in the examples was evaluated for dispersibility by the following method. Further, the recording liquid obtained in the examples was applied to an ink jet printer (“MJ7” manufactured by Epson Corporation).
00V2C ”), and recording was performed, and the water resistance, friction resistance, and light resistance of the recorded matter were evaluated by the following methods. Table 3 shows the results. Further, when the recording liquid obtained in the example was stored at -40 ° C for one week and then naturally thawed, the initial viscosity was maintained and stable ejection characteristics were exhibited. When stored in a 50 ° C constant temperature bath for one month, the initial viscosity was maintained and stable injection characteristics were exhibited. Also, -4
A cycle of 7 hours at 0 ° C, 7 hours at room temperature, and 7 hours at 50 ° C
When the printing was repeated several times, the initial printing characteristics and the physical properties of the recording liquid were maintained.

Water-resistant copy paper "Xerox 402"
No. 4 ", left for 6 hours, immersed in tap water for 5 minutes, measured the OD value before and after the test, and showed the percentage remaining. Abrasion Resistance The change in the printed area when the solid printed on the art paper was rubbed three times with a wet cotton swab was visually evaluated. Lightfastness After printing and laminating on the coated synthetic paper, it was exposed for 500 hours with a fade meter, and the color difference before and after exposure was determined. Dispersibility A change in the particle size of the recording liquid after storage at 50 ° C. for 7 days was measured. Good: Change of less than 15 nm Bad: Change of 15 nm or more

[0041]

[0042]

The recording liquid of the present invention is a water-dispersion type ink-jet recording liquid in which a pigment is dispersed in an aqueous liquid, but has a stable dispersibility and a good discharge stability at a nozzle. It can be used in the fields of office document creation, cardboard marking, numbering, barcode, etc., on-demand printing, and simple printing.

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-6-145545 (JP, A) JP-A-5-247391 (JP, A) JP-A-3-210375 (JP, A) 18630 (JP, A) JP-A-10-110110 (JP, A) JP-A-10-110111 (JP, A) JP-A-10-110112 (JP, A) JP-A-10-110127 (JP, A) JP-A-10-53716 (JP, A) JP-A-9-208849 (JP, A) JP-A-9-40898 (JP, A) JP-A 8-283596 (JP, A) JP-A 8-157759 (JP, A) JP-A-5-186704 (JP, A) JP-A-4-227669 (JP, A) JP-B-50-4019 (JP, B1) (58) Fields investigated (Int. Cl. ⁷⁾ , DB name) C09D 11/00-11/20 C09B 67/00-67/52 C09C 3/00-3/12

Claims (5)

(57) [Claims] 1. An ink jet recording liquid comprising an organic pigment dispersed in an aqueous liquid, wherein the organic pigment is dispersed in a solvent having no reactivity with sulfonic acid.
Or sulfonated pyridine salt or sulfamic acid after accordingly
Sulfonating agent selected from the group
An ink jet recording liquid, which is a treated pigment having a sulfonic acid group introduced therein . 2. A solvent having no reactivity with sulfonic acid,
Ink-jet recording liquid according to claim 1, characterized in that the solvent having no active proton. 3. The recording liquid according to claim 1, wherein the solvent having no active proton is N-methyl-2-pyrrolidone or sulfolane. 4. A process inkjet recording liquid according to any one of claims 1 to 3, wherein an average particle diameter measured by a laser scattering method is 10~150nm pigment. 5. A process claims 1, characterized in that it comprises 0.1 to 10% by weight solids of pigment to ink-jet recording liquid according to any of the preceding paragraphs.