JPH10251589A - Color material dispersion, ink for ink jet recording and ink jet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject dispersion excellent in long-term storage stability and environmental stability by using a polymer dispersion obtained from a specific raw material as a dispersion. SOLUTION: This color material dispersion comprises (A) a water-insoluble or slightly water-soluble coloring material, (B) a polymer dispersion obtained by subjecting a sulfonated product obtained by sulfonating creosote oil to formalin condensation and neutralizing the condensed product and (C) a water-soluble medium. When concentrated sulfuric acid is used as the sulfonating agent in preparing the component B, creosote oil is charged into a reactor having an agitator and then, concentrated sulfuric acid is added thereto at 150-170 deg.C and sulfonation is preferably carried out for 1-2hr. Weight average molecular weight of the component B is preferably 2,000 to 50,000. It is preferable to include 15-30wt.% component A, 1.5-30wt.% component B and 50-83wt.% component C in the objective dispersion. The weight ratio of the components A/B is preferably (100/100) to (100/30). Pigment, oil-soluble dye, etc., is preferably used as the component A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various inks, particularly to a colorant dispersion useful as a precursor of an ink for ink jet recording. The present invention also relates to an ink jet recording ink and an ink jet recording method using the colorant dispersion.

[0002]

2. Description of the Related Art An ink jet recording system is a recording system in which ink droplets are directly ejected from very fine nozzles onto a recording member and adhered to obtain characters and images. According to this method, not only has the advantage that the device to be used is low noise and has good operability, but also has the advantages that colorization is easy and plain paper can be used as a member to be recorded. Have been.

[0003] As inks used in the ink jet recording system, inks containing various coloring materials are used. Among such inks, an ink in which a coloring material is dispersed in a liquid medium, for example, a pigment ink or an aqueous ink of an oil-soluble dye, or an aqueous ink of a disperse dye, has a long term due to the low dispersibility of the coloring material. Storage stability (Long-term storage stability as used herein means that the sedimentation of the coloring material and the thickening of the ink do not occur even in a high-temperature environment of 80 ° C. as well as 60 ° C., which is a conventionally used dispersion stability test environment. ) And stability under a severe storage environment (that is, no sedimentation of coloring material or thickening of ink occurs even under a storage environment of a freeze-thaw-high-temperature environment cycle. Stability ”) is low.

[0004] In particular, the high-concentration colorant dispersion, which is a precursor of the ink, has a problem that the long-term storage stability and the environmental stability are further reduced due to the aggregation and sedimentation of the colorant.

Further, when printing is performed using an ink for ink-jet recording prepared from a color material dispersion liquid containing agglomerated color materials and the like, foreign matter adheres and accumulates on a printer head, causing clogging, resulting in a long-term use of the ink. There has been a problem that the ejection stability and printing quality deteriorate.

Further, when an aqueous medium is used as the liquid medium, there is a problem that the fixability of the ink to a non-permeable recording member such as a plastic sheet is low, and the scratch resistance of a printed image is poor.

Accordingly, an object of the present invention is to provide a colorant dispersion having excellent long-term storage stability and environmental stability. Another object of the present invention is to provide an ink jet recording ink having excellent long-term storage stability and environmental stability. Another object of the present invention is to provide an ink jet recording ink which is excellent in fixability to a non-permeable recording member and can obtain a printed image having high abrasion resistance. A further object of the present invention is to provide an ink jet recording ink which has high print quality and long-term ejection stability, in which foreign matter is prevented from adhering and accumulating on a printer head and clogging.

[0008]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a colorant dispersion which can achieve the above object by using a polymer dispersant produced from a specific raw material by a specific method. It has been found that an ink for inkjet recording can be obtained.

The present invention has been made on the basis of the above findings. In a colorant dispersion containing a water-insoluble or sparingly water-soluble colorant, a dispersant and a water-soluble medium, creosote oil is used as a sulfonate. The above object has been attained by providing a colorant dispersion characterized by using a polymer dispersant obtained by subjecting a sulfonated product obtained by the polymerization to formalin condensation and then neutralizing the resultant.

[0010] The present invention also provides an ink for ink-jet recording, characterized in that the above-mentioned colorant dispersion is diluted with water.

Further, the present invention provides an ink jet recording method characterized in that the ink jet recording ink is ejected from a nozzle to a recording member as ink droplets to perform recording.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The colorant dispersion of the present invention is used as a precursor of various inks, and contains a water-insoluble or poorly water-soluble colorant, a dispersant, and a water-soluble medium. . The colorant dispersion of the present invention is characterized in that, as the dispersant, a polymer dispersant obtained by formalin condensing a sulfonated product obtained by sulfonating creosote oil and then neutralizing the sulfonated product is used. It is assumed that.

The above-mentioned polymer dispersant is described in detail.
IS K 2439-83 and CAS No. 8001-
It is a mixture of aromatic compounds specified in 58-9, and contains polynuclear aromatic compounds such as naphthalenes and anthracenes and mononuclear aromatic compounds such as benzenes as the aromatic compounds.

To prepare the above polymer dispersant, first,
The creosote oil is sulfonated with a sulfonating agent, for example, concentrated sulfuric acid or fuming sulfuric acid to obtain a sulfonated product.
Sulfonation can be carried out by a known method. For example, when concentrated sulfuric acid is used as a sulfonating agent, creosote oil is charged into a reactor equipped with a stirrer, and the sulfonating oil is charged to 110 to 200.
Sulfonation can be carried out by gradually adding concentrated sulfuric acid at a temperature of 150 ° C., preferably 150 to 170 ° C. and terminating the reaction in 0.5 to 10 hours, preferably 1 to 2 hours.

Next, the sulfonated product is subjected to formalin condensation using formalin to form a formalin condensate.
The formalin condensation can be performed by a known method. For example, the above sulfonate is cooled to 100 ° C.
Formalin condensation can be performed by gradually dropping an aqueous solution of formalin and condensing for 1 to 20 hours, preferably 7 to 10 hours. The degree of condensation of the formalin condensate can be adjusted, for example, by adjusting the charge ratio of the sulfonate to formalin.

The above formalin condensate obtained by the formalin condensation is then neutralized with a predetermined neutralizing agent to obtain the above polymer dispersant. For the neutralization, for example, a method known as liming soda tion is used. That is, a method of neutralizing by adding calcium hydroxide or calcium carbonate, filtering and separating the generated calcium sulfate, and adding sodium carbonate, ammonium carbonate, potassium carbonate or the like to the filtrate to obtain a neutralized product is used. Therefore, the polymer dispersant obtained by the neutralization,
The sodium salt, ammonium salt, potassium salt and the like of the formalin condensate are obtained.

The thus obtained polymer dispersant preferably has a weight average molecular weight of 2,000 to 50,000 in view of the viscosity of the colorant dispersion and the heat-resistant storage stability. The weight average molecular weight can be controlled by adjusting the degree of condensation of the formalin condensate (the method of adjusting the degree of condensation of the formalin condensate is as described above).

As the polymer dispersant, a commercially available product can be used. Examples of such commercially available products include Demol C (trade name) manufactured by Kao Corporation.

By using the above-mentioned polymer dispersant, the dispersibility of the coloring material is remarkably improved, and the coloring material is finely divided, and aggregation and sedimentation associated therewith are effectively prevented. Further, since the coloring material becomes fine particles, the adhesion (fixing property) of the coloring material to the recording member is improved. The degree of micronization in the colorant dispersion of the present invention is such that when 200 g of the colorant dispersion is subjected to constant pressure filtration (3.5 kg / cm ² ) with a membrane filter having a pore size of 5 μm, the filtration speed does not change at all and the pore size is 2 μm. Filtration of 200 g of the colorant dispersion with a membrane filter (3.5 kg / c)
In the case of m ² ), the degree of micronization is extremely high such that even if the filtration rate is reduced, the whole amount passes.

The polymer dispersant is preferably incorporated in the colorant dispersion of the present invention in an amount of 0.5 to 40% by weight, more preferably 1 to 35% by weight, and even more preferably 1.5 to 40% by weight.
-30% by weight. If the amount of the polymer dispersant is less than 0.5% by weight, depending on the type of the coloring material, it may not be possible to prepare the coloring material at the stage of preparing the coloring material dispersion, or even if it can be prepared, The intended long-term storage stability, environmental stability, and abrasion resistance may not be exhibited in the color material dispersion liquid. If the content exceeds 40% by weight, the adsorption of the dispersant to the color material is particularly hindered. Therefore, it is more preferable to be within the above range.

Next, the coloring material and the water-soluble medium which are essential components other than the above-mentioned polymer dispersant in the coloring material dispersion of the present invention will be described. As the colorant to be mixed in the colorant dispersion of the present invention, a water-insoluble or poorly water-soluble colorant is used.
As the water-insoluble or hardly water-soluble coloring material, various pigments, oil-soluble dyes, disperse dyes and the like are used.

Examples of the pigment include carbon black; I. Pigment Yellow 1, 5, 12, 1
4, 17, 24, 42, 53, 83, 95, 97, 98
And 100; I. Pigment Red 1, 3, 4,
5, 17, 22, 31, 48, 49, 53, 63, 6
4, 81: 1, 88 and 101; I. Pigment
Blue 1, 15, 16, 27, 28, 29, 56, 60
And 63; and C.I. I. Pigment Black 1 and 11 can be used, and carbon black is particularly preferable.

Examples of the oil-soluble dye include C.I.
I. Solvent Black 3; I. Solvent Yellow 19; C.I. I. Solvent Red 8, 24, 4
3, 51, 72 and 73; I. Solvent Violet 3; C.I. I. Solvent Blue 2 and 11;
C. I. Solvent Green 3 and 7; and C.I.
I. Solvent Orange 2 or the like can be used.

Examples of the disperse dye include C.I. I.
Disperse Yellow 3, 5, 56, 60 and 64;
C. I. Disperse Red 4, 5, 60, 72, 7
3 and 91; I. Disperse Violet 2
6; I. Disperse Blue 3, 7, 56, 60
And 79; and C.I. I. Disperse Orange 13
And 30 can be used.

When a pigment is used as the water-insoluble or poorly water-soluble coloring material, the average primary particle size of the pigment is determined in view of the desired long-term storage stability, environmental stability, abrasion resistance, and filterability in the preparation step. It is preferably from 10 to 150 nm. In particular, when carbon black is used as the pigment, from the viewpoint of a structure unique to carbon,
The average particle size of the primary particles is preferably from 10 to 100 nm, more preferably from 10 to 80 nm, and even more preferably from 10 to 50 nm.

In particular, when carbon black is used as the water-insoluble or hardly water-soluble coloring material, DIN ISO 7 in a powder state is used as the carbon black.
Oil absorption based on 87/5 (flow point method) is 50-
1000 g / 100 g (particularly 500 to 950 g / 100
g, especially 800 to 950 g / 100 g). The oil absorption is a measure of the particle size of the secondary particles of carbon black.If the oil absorption does not satisfy the above conditions, carbon black is likely to aggregate, and the long-term storage stability of the colorant dispersion and There is a possibility that the environmental stability may be reduced, or ejection failure may occur when printing is performed using the inkjet recording ink prepared from the colorant dispersion liquid.

The carbon black is a BE
Preferably T specific surface area of 20 to 500 m ² / g, more preferably from 220~500m ² / g, and still more preferably 220~400m ² / g.

The water-insoluble or poorly water-soluble colorant is preferably incorporated in the colorant dispersion of the present invention in an amount of 5 to 40% by weight, more preferably 10 to 35% by weight, and still more preferably 15 to 30% by weight. %. If the amount of the water-insoluble or poorly water-soluble coloring material is less than 5% by weight, not only a good dispersion cannot be obtained at the stage of preparing the coloring material dispersion, but also the printing density when diluted into ink becomes poor. If the amount is lower than 40% by weight, the effect is saturated in terms of print density.

The amount of the water-insoluble or poorly water-soluble colorant is determined by the weight ratio of the colorant to the polymer dispersant (former / latter) in relation to the amount of the polymer dispersant.
Is 100/120 to 100/10 (particularly, 100/11
5-100 / 25, especially 100 / 100-100 /
30) is preferable from the viewpoint of the properties of the colorant dispersion, the long-term storage stability as an ink, and the environmental stability.

The water-soluble medium incorporated in the colorant dispersion of the present invention is used as a liquid medium, and examples thereof include water (preferably purified water) and a water-soluble solvent. The type of the water-soluble solvent is not particularly limited as long as it has a function as a wetting agent or a humectant, for example, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol,
Glycols such as tetraethylene glycol and polyethylene glycol; glycerin; diethylene glycol diethyl ether, diethylene glycol monobutyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, methyl carbitol, ethyl carbitol, butyl carbitol, ethyl Ethers of polyhydric alcohols such as carbitol acetate, diethyl carbitol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, and propylene glycol monomethyl ether; acetates; thiodiglycol; N-methyl-2-pyrrolidone; 1,3-dimethylimidazolidinone; formamide; dimethylforma It can be used nitrogen-containing compounds such as de, dimethyl sulfoxide one or two or more kinds. These water-soluble solvents are preferably blended in the colorant dispersion of the present invention in an amount of 5 to 50% by weight, and 10 to 30% by weight.
More preferably, it is blended by weight. The amount of the water-soluble medium (the total amount of water and water-soluble solvent) is preferably 30 to 94% by weight, more preferably 40 to 89% by weight, and still more preferably 50 to 90% by weight in terms of dispersion efficiency. ~
83% by weight.

Optional components can be added to the colorant dispersion of the present invention, if necessary, in addition to the above essential components.
Such optional components include, for example, dispersants other than the above-mentioned polymer dispersants. The dispersant is not particularly limited, but, for example, as anionic surfactants, alkyl sulfonates, alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkanes or olefin sulfonates, alkyl sulfates , A surfactant selected from the group consisting of polyoxyethylene alkyl or alkyl aryl ether sulfate, alkyl phosphate, alkyl diphenyl ether disulfonate, ether carboxylate, alkyl sulfosuccinate, α-sulfo fatty acid ester, and fatty acid salt Agents, condensates of higher fatty acids and amino acids, naphthenates and the like can be used. Anionic surfactants preferably used are alkyl benzene sulphonates (especially linear alkyl), alkanes or olefin sulphonates (especially secondary alkane sulphonates, α
Olefin sulfonates), alkyl sulfates, polyoxyethylene alkyl or alkyl aryl ether sulfates (especially polyoxyethylene alkyl ether sulfates), alkyl phosphates (especially monoalkyl), ether carboxylate , An alkyl sulfosuccinate, an α-sulfofatty acid ester, and a surfactant selected from the group consisting of fatty acid salts, particularly preferably an alkyl sulfonate,
Alkyl benzene sulfonates (especially those of straight chain alkyls), polyoxyethylene alkyl or alkyl aryl ether sulfates (especially polyoxyethylene alkyl ether sulfates), and alkyl sulfates. These can be used alone or in combination of two or more. In addition, as a cationic surfactant, an aliphatic amine salt, a quaternary ammonium salt, a sulfonium salt, a phosphonium salt, or the like can be used. These can be used alone or in combination of two or more. Further, as a nonionic surfactant, polyoxyethylene alkyl ether, polyoxyethylene alkyl aryl ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester and alkyl A surfactant or the like selected from the group consisting of (poly) glycoxides can be used.
Nonionic surfactants preferably used are surfactants selected from polyoxyethylene alkyl ethers and polyoxyethylene alkyl aryl ethers. These can be used alone or in combination of two or more. In addition, as the amphoteric surfactant, an amino acid type or betaine type compound or the like can be used. Examples of the polymer dispersant include gelatin, proteins such as casein, natural gums such as gum arabic, glucoxides such as saponin, alkyl cellulose, carboxyalkyl cellulose, cellulose derivatives such as hydroxyalkyl cellulose, lignin sulfonate, shellac and the like. Natural polymer, polyacrylate, styrene-acrylic acid copolymer salt, vinylnaphthalene-acrylic acid copolymer salt, styrene-maleic acid copolymer salt, vinylnaphthalene-maleic acid copolymer salt, polyphosphoric acid, etc. Anionic polymer,
Examples thereof include nonionic polymers such as polyvinyl alcohol, polyvinylpyrrolidone, and polyalkylene glycol. When used, one or more of these can be used.

The colorant dispersion of the present invention is used as a precursor of various inks as described above, and is generally a viscous liquid. The solid content concentration of the colorant dispersion is preferably from 5 to 70% by weight, and more preferably from 20 to 70% by weight, from the viewpoint of the apparatus efficiency in the preparation step and the particle size distribution quality of the resulting fine particle dispersion. Is more preferred.

The method for preparing the colorant dispersion of the present invention is not particularly limited, but is preferably prepared by the method described below. That is, first, (1) the water-insoluble or hardly water-soluble colorant, the polymer dispersant, the water-soluble medium, and optional components (the other dispersants and the like) as needed are stirred with a dissolver to prepare a preliminary dispersion. Prepared and then (2)
The colorant dispersion is obtained by dispersing the preliminary dispersion with a wet medium mill such as a Dynomill.

The above-mentioned preparation method will be described in detail. In the step (1), it is sufficient to use a high-speed and high-shearing dissolver between the coloring material (particularly, pigment) and the polymer dispersant. It is preferable from the viewpoint of mixing and dispersion, and specifically, it is preferable to stir under a condition of a rotation number of 500 to 6000 rpm. Further, in the step (2), from the viewpoint of more sufficient mixing and dispersion of the coloring material (particularly, pigment) and the polymer dispersant, the temperature is 10 to 80 ° C. (particularly 25 ° C.).
６０60 ° C.) at 0.1 kg / kg of the preliminary dispersion.
It is preferable to disperse for 5 to 3.0 hours (particularly, 1.5 to 3.0 hours). In the above-mentioned preparation method, a circulation operation method in which the above-mentioned step (1) and the above-mentioned step (2) are repeated a predetermined number of times may be used.

Next, an ink jet recording ink prepared by using the colorant dispersion of the present invention as a precursor will be described. The inkjet recording ink is an aqueous ink obtained by diluting the colorant dispersion with at least water, preferably purified water (ion-exchanged water). The degree of dilution is such that the concentration of each component in the ink for ink jet recording falls within a predetermined range. More specifically, the preferred range of the concentration of each component in the ink for inkjet recording is as follows. The colorant: 2 to 10% by weight, particularly 3 to 5% by weight The polymer dispersant: 0.2 to 10% by weight, especially 0.3 to 10% by weight
5% by weight water: 80-98% by weight, especially 90-97% by weight

In the preparation of the ink for ink jet recording, an optional component which can enhance various performances as the ink for ink jet recording may be added during the dilution. Examples of such optional components include various surfactants (anionic, cationic, nonionic, and amphoteric surfactants) that can further enhance the dispersibility of the coloring material, antifoaming agents such as silicone compounds, and chloromethylphenol compounds. And the like, a chelating agent such as EDTA, an oxygen absorber such as sulfite, and the like. These optional components are preferably 1 to 5% by weight (particularly 2
~ 3% by weight).

In the preparation of the ink for ink-jet recording, after the colorant dispersion is diluted, coarse particles (preferably 2 μm) are formed using a membrane filter or the like.
(More preferably, 1 μm or more) is preferably removed. This is preferable because ink that does not cause clogging can be obtained.

The ink-jet recording ink is used in any printer as long as it is a printer using an ink-jet recording system, that is, a recording system in which the ink is ejected from a nozzle to a recording member as ink droplets to perform recording. be able to. For example, a thermal jet recording type printer that performs recording using thermal energy from a heater or the like of a heating resistance element disposed in a printer head, and a piezoelectric element recording that performs recording using a piezoelectric element disposed in the printer head Any type of printer can be used.

The recording member may be plain paper or OHP.
A boehmite-containing transparent plastic sheet widely used as a sheet is used. The ink for ink jet recording, especially when using a non-permeable recording member such as a plastic sheet, for which it has been conventionally difficult to enhance the fixability, the colorant is finely divided by the action of the polymer dispersant. And a very high fixing property can be exhibited, and a printed image having high scratch resistance can be obtained. When plain paper is used as the recording member, an aqueous solution such as polyester emulsion, acrylic, silicone emulsion, or PVA is applied on the printed image after printing to further enhance the scratch resistance of the printed image. be able to.

The coloring material dispersion, ink for ink jet recording and ink jet recording method of the present invention have been described above in detail. As the polymer dispersant used in the present invention, creosote oil is used as a raw material and the above method is used. Using a salt of a formalin condensate of a mixture consisting of anthracenesulfonic acid, naphthalenesulfonic acid and alkylnaphthalenesulfonic acid and, if necessary, phenolsulfonic acid and multi-membered aromatic sulfonic acid, in place of those prepared by Can also.

[0041]

The following examples illustrate the effectiveness of the colorant dispersion, the ink for ink jet recording and the ink jet recording method of the present invention. However, the scope of the present invention is not limited to such an embodiment. In the following examples, “parts” and “%” mean “parts by weight” and “% by weight”, respectively, unless otherwise specified.

Example 1 [Preparation of Coloring Material Dispersion A] The following components were mixed with purified water in the mixing ratio shown below, and a dissolver (a high-speed / high-shearing force dissolver, manufactured by Shinmaru Enterprises) was used. (Temperature: 30 ° C., time: 15 minutes, number of revolutions: 6000)
rpm), a preliminary dispersion having a solid content of 20% was prepared.・ 100 parts of carbon black (acid) (BET specific surface area: 260 m ² / g, oil absorption: 840 g)
/ 100 g, average particle size of primary particles: 15 nm) ・ Polymer dispersant 62.5 parts (solid content) [Demol C (trade name) manufactured by Kao Corporation] ・ Diethylene glycol 37.5 parts Then, the above preliminary dispersion The liquid was dispersed under the following dispersion conditions.・ Mill: Dynomill ・ Beads: Yttria-stabilized zirconia beads (0.5
mmφ) ・ Dispersion time: 2 hr / kg (2 per kg of preliminary dispersion)
(Dispersion of time) Dispersion temperature: 60 ° C. ± 5 ° C. A color material dispersion obtained by returning the color material dispersion obtained by dispersion to the above-mentioned dissolver, stirring, and then dispersing again with the above dyno mill is used. A was prepared.

Example 2 [Preparation of Ink A for Ink-Jet Recording] Purified water was added to the color material dispersion A so that the concentration of carbon black was 5%, and the color material dispersion A was dissolved using a dissolver. Was stirred and diluted. Next, the mixture was filtered through a 1.2-micron filter to prepare ink A for inkjet recording.

Example 3 [Preparation of Coloring Material Dispersion B] The following components were mixed with purified water in the mixing ratio shown below, and a dissolver (high speed / high shearing force dissolver, manufactured by Shinmaru Enterprises) was used. (Temperature: 30 ° C., time: 15 minutes, number of revolutions: 6000)
rpm), a preliminary dispersion having a solid content of 20% was prepared.・ 100 parts of carbon black (acid) (BET specific surface area: 320 m ² / g, oil absorption: 920 g)
/ 100 g, average particle size of primary particles: 13 nm) ・ Polymer dispersant 62.5 parts (solid content) [Demol C (trade name) manufactured by Kao Corporation] ・ Diethylene glycol 37.5 parts Then, the above preliminary dispersion The liquid was dispersed under the following dispersion conditions.・ Mill: Sand mill ・ Beads: Zirconia beads (0.5 mmφ) ・ Dispersion time: 2 hr / kg (2 per kg of preliminary dispersion)
(Dispersion of time) Dispersion temperature: 25 ° C. ± 5 ° C. The color material dispersion obtained by dispersion is returned to the above-mentioned dissolver, stirred, and then dispersed again by the above-mentioned sand mill. B was prepared.

[Example 4] [Preparation of ink for ink-jet recording B] Purified water was added to the above-mentioned color material dispersion B so that the concentration of carbon black became 5%, and the color material dispersion B was prepared using a dissolver. Was stirred and diluted. Next, the mixture was filtered through a 1.2-micron filter to prepare ink B for inkjet recording.

[Comparative Example 1] [Preparation of Coloring Material Dispersion C] The following components were mixed with purified water at the following compounding ratio, and a dissolver (a high-speed / high-shear-force dissolver, manufactured by Shinmaru Enterprises) was used. (Temperature: 30 ° C., time: 15 minutes, number of revolutions: 6000)
rpm), a preliminary dispersion having a solid content of 20% was prepared.・ 100 parts of carbon black (acid) (BET specific surface area: 320 m ² / g, oil absorption: 920 g)
/ 100 g, average particle size of primary particles: 13 nm) ・ Styrene-acrylic acid-ethyl acrylate copolymer 62.5 parts (solid content) (acid value: 180, weight average molecular weight: 15000) ・ diethylene glycol 37.5 parts Next, the preliminary dispersion was dispersed under the following dispersion conditions.・ Mill: Sand mill ・ Beads: Zirconia beads (0.5 mmφ) ・ Dispersion time: 4 hr / kg (4 per kg of preliminary dispersion)
(Dispersion of time) Dispersion temperature: 25 ° C. ± 5 ° C. The color material dispersion obtained by dispersion is returned to the above-mentioned dissolver, stirred, and then dispersed again by the above-mentioned sand mill. C was prepared.

[Comparative Example 2] [Preparation of ink for ink-jet recording C] Purified water was added to the above-mentioned color material dispersion C so that the concentration of carbon black was 5%, and the color material dispersion C was prepared using a dissolver. Was stirred and diluted. Next, the mixture was filtered through a 1.2-micron filter to prepare an ink C for inkjet recording.

[Comparative Example 3] [Preparation of Coloring Material Dispersion D] The following components were mixed with purified water at the following compounding ratio, and a dissolver (a high-speed / high-shear-force dissolver, manufactured by Shinmaru Enterprises) was used. (Temperature: 30 ° C., time: 15 minutes, number of revolutions: 6000)
rpm), a preliminary dispersion having a solid content of 20% was prepared.・ 100 parts of carbon black (acid) (BET specific surface area: 110 m ² / g, oil absorption: 400 g / 100 g, average particle size of primary particles: 29 nm) ・ Styrene-α-methylstyrene-acrylic acid-ethyl acrylate copolymer 62 0.5 parts (solid content) (acid value: 168, weight average molecular weight: 10100) diethylene glycol 37.5 parts Next, the above preliminary dispersion was dispersed under the following dispersion conditions.・ Mill: Sand mill ・ Beads: Zirconia beads (0.5 mmφ) ・ Dispersion time: 4 hr / kg (4 per kg of preliminary dispersion)
(Dispersion of time) Dispersion temperature: 25 ° C. ± 5 ° C. The color material dispersion obtained by dispersion is returned to the above-mentioned dissolver, stirred, and then dispersed again by the above-mentioned sand mill. D was prepared.

Comparative Example 4 [Preparation of Ink D for Ink-Jet Recording] Purified water was added to the above-mentioned color material dispersion D so that the concentration of carbon black became 5%, and the color material dispersion D was produced using a dissolver. Was stirred and diluted. Next, the mixture was filtered through a 1.2-micron filter to prepare Ink D for inkjet recording.

[Evaluation of Performance] In order to evaluate the long-term storage stability and environmental stability of the colorant dispersions and ink jet recording inks obtained in Examples and Comparative Examples, the following measurement methods were used. In addition, the ink jet recording ink was also evaluated for ink jet ink suitability.

<Long-term storage stability>
With respect to the colorant dispersion and the ink for inkjet recording after storage at 120 ° C. for 120 hours and at 80 ° C. for 120 hours, the solid content concentration and the viscosity were measured according to the following measurement methods, respectively, and the change in viscosity and the change in pigment sedimentation were measured. , And the long-term storage stability based on the change in viscosity and the change in pigment sedimentability was evaluated according to the following evaluation criteria. The results are shown in Table 1 below.

The viscosity was measured at 20 ° C. using an ELD type viscometer (manufactured by Tokimec). The measurement was performed one minute after the preliminary rotation. Especially,
Ink for inkjet recording is 10 rpm or 50 rpm.
It was measured at rpm.

Pigment sedimentation The solid content concentration (%) of the obtained colorant dispersion and the ink for ink jet recording and the solid content concentration (%) after centrifugation at 2500 G for 20 minutes were measured, and the following formula ( From 1), the rate of decrease in solid content concentration by centrifugation was determined, and the value was used as an index of change in pigment sedimentation. The centrifugation was performed by collecting 20 g of the obtained colorant dispersion and the ink for inkjet recording in a test tube, respectively, and the solid content after centrifugation was measured by collecting 6 g of the supernatant. .

[0054]

(Equation 1)

Evaluation Criteria : In the case of a colorant dispersion liquid with respect to viscosity change Viscosity rise is 50 cP or less ··· Viscosity rise exceeds 50 cP and 100 cP or less ··· Viscosity rise is 100 cP × In the case of ink for inkjet recording, the viscosity rise is 1 cP or less ..... ○ The viscosity rise exceeds 1 cP and 2 cP or less. Viscosity rise exceeds 2 cP ···························································································································································· ··· ○ Pigment sedimentation rise more than 5% and 10% or less · △ Pigment sedimentation rise more than 10% ····· ×

<Environmental Stability> The obtained coloring material dispersion and the ink for ink-jet recording were repeatedly stored for 10 cycles under the following storage conditions as one cycle. The environmental stability based on pigment settability was evaluated. The results are shown in Table 1 below. Storage conditions (1 cycle) [Normal temperature (25 ° C), 2 hours] ··· [60 ° C, 5 hours]
... [Normal temperature (25 ° C), 2 hours] ... [Frozen (-1
0 ° C), 5 hours] ... [Normal temperature (25 ° C), 2 hours]

[0057]

[Table 1]

<Appropriateness of ink-jet recording ink> The obtained ink-jet recording ink is printed using an ink-jet printer which performs recording by discharging ink droplets by thermal energy, and discharge stability, abrasion resistance and prevention of clogging. The property was evaluated by the following method. As a result, the ink jet recording inks of the present invention (Examples 2 and 4) were free from image deterioration such as blurring and were excellent in ejection stability. Table 2 shows other results.

Ejection Stability A continuous document of about 600 characters on A4 size plain paper
Printing was performed on one sheet, and the ejection stability was evaluated. Boehmite-containing OHP sheets (boehmite-based OHP sheets) widely used in scratch-resistant plain paper and commercial OHP sheets
Sheet), and the scratch resistance of the printed image was evaluated according to the following criteria.・ Even if the printed image is rubbed with a nail, there is no loss of the printed image and the surroundings of the printed image are not stained.
○ ・ Even if the printed image is rubbed with a nail, the printed image is not lost, but the periphery of the printed image may be stained. Occurs ...
... × clogging prevention property After confirming with the printed matter that the ejection state is normal,
The printing condition when printing was performed again at one week intervals was evaluated according to the following criteria. There is no image quality deterioration such as blurring, or blurring occurs, but it returns to the normal ejection state by one cleaning.
・ ・ ・ ・ ○ ・ Removal to normal ejection state by cleaning three times, but blurring etc. ・ ・ ・ ・ ・ ・ △ ・ Recovery to normal ejection state even after cleaning three times ・ ・ ・ ・ ×

[0060]

[Table 2]

As is clear from the results shown in Tables 1 and 2, the coloring material dispersions of the present invention (Examples 1 and 3) and the inks for ink jet recording (Examples 2 and 3) each containing a specific polymer dispersant. 4) is superior to Comparative Examples 1 to 4 in long-term storage stability and environmental stability.
Further, the ink jet recording ink of the present invention (Example 2)
And 4) are superior to Comparative Examples 2 and 4 in terms of ejection stability, abrasion resistance, and anti-clogging properties required for ink-jet inks.

[0062]

According to the present invention, it is possible to obtain a colorant dispersion liquid and an ink jet recording ink having excellent long-term storage stability and environmental stability. Further, according to the present invention, there is obtained an ink jet recording ink which is particularly excellent in fixability to a non-permeable recording member and is capable of obtaining a printed matter having high abrasion. Further, according to the present invention, it is possible to obtain an ink jet recording ink having high printing quality and long-term ejection stability, in which foreign matters are prevented from adhering and accumulating on a printer head and clogging.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yoshiaki Tsujii 2606 Kabane-cho, Akaga-cho, Haga-gun, Tochigi Prefecture At Kao Corporation Research Institute

Claims (6)

[Claims] 1. A colorant dispersion comprising a water-insoluble or sparingly water-soluble colorant, a dispersant and a water-soluble medium, wherein, as the dispersant, a sulfonated product obtained by sulfonating creosote oil is subjected to formalin condensation. A colorant dispersion, characterized by using a polymer dispersant obtained by neutralizing the resultant. 2. The method according to claim 1, wherein the concentration of the coloring material is 5 to 40% by weight, the concentration of the polymer dispersant is 0.5 to 40% by weight, and the concentration of the water-soluble medium is 30 to 94% by weight. is there,
The colorant dispersion according to claim 1. 3. The colorant dispersion according to claim 1, wherein the weight ratio of the colorant to the polymer dispersant (former / latter) is from 100/120 to 100/10. 4. The colorant dispersion according to claim 1, wherein the water-insoluble or poorly water-soluble colorant is a pigment, an oil-soluble dye or a disperse dye. 5. An ink for ink-jet recording, wherein the colorant dispersion according to claim 1 is diluted with water. 6. An ink jet recording method comprising discharging the ink for ink jet recording according to claim 5 as ink droplets from a nozzle onto a recording member to perform recording.