JPH10298474A - Ink for ink jet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ink excellent in long-term storage stability and environmental stability by forming an ink comprising a water-insoluble or difficultly water-soluble colorant, a dispersant and a water-soluble medium, wherein the dispersant is a polymeric dispersant obtained by condensing a sulfonate of aromatic compound mixture containing alkyl naphthalenes and phenolic compounds with formalin and neutralizing the condensate. SOLUTION: The aromatic compound mixture contains aromatic compounds represented by formula I (where R1 and R2 are each H or a 1-5C alkyl) and formula II (wherein R3 and R4 are each H or a 1-5C alkyl). Compounds of formula I are desirably dimethylnaphthalene, methylnaphthalene and butylnaphthalene. Compounds of formula II are particularly desirably cresol, xylenol, phenol and ethylphenol. The use ratio of the compound of formula I to the compound of formula II is desirably 1/3 to 1/15 by weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink for ink jet recording.

[0002]

2. Description of the Related Art As inks used in an 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, such as a pigment-dispersed ink or an aqueous ink of an oil-soluble dye, or an aqueous ink of a disperse dye, due to the low dispersibility of the coloring material Long-term storage stability (here, long-term storage stability refers to the sedimentation phenomenon of the colorant and the thickening phenomenon of the ink in a high-temperature environment of 80 ° C. as well as 60 ° C., which is a conventionally used dispersion stability test environment. Stability in a severe storage environment (that is, no sedimentation of the coloring material or thickening of the ink even in a storage environment of a freeze-thaw-high-temperature environment cycle). "Environmental stability" is low.

For the purpose of solving the above problem, for example, Japanese Patent Application Laid-Open No. 8-291266 proposes to use an aromatic polyvalent anion dispersant as a dispersant for an ink for ink jet recording. 8-33
No. 3531 proposes to use a condensation product of 2-naphthalenesulfonic acid and formaldehyde as a dispersant.

However, the ink jet recording ink described in the above publication has the following disadvantages. That is, the ink jet recording ink described in JP-A-8-291266 is intended to prevent bleeding in textile printing by ink jet, and to improve the long-term storage stability and environmental stability of the ink, and further to improve the plastic sheet and the like. No studies have been made on the improvement of the fixability of the ink to the non-permeable recording member and the improvement of the scratch resistance of the printed image. Further, even when the ink for ink jet recording described in JP-A-8-333533 is used, the long-term storage stability and environmental stability of the ink can be improved, and the fixing property of the ink to a non-permeable recording member such as a plastic sheet can be improved. The improvement of the scratch resistance of the printed image, the low bleeding property of the printed image, the improvement of the print density, and the like were still insufficient.

Accordingly, an 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. It is a further object of the present invention to provide an ink jet recording ink capable of obtaining a printed image having a low bleeding property and a high print density.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the use of a polymer dispersant prepared from a specific aromatic compound by a specific method can achieve the above-mentioned object. It was found that an ink for use was obtained.

The present invention has been made based on the above findings. In an ink jet recording ink containing a water-insoluble or hardly water-soluble coloring material, a dispersant and a water-soluble medium, the dispersant is represented by the following formula (I) ) And the following formula (II)
An ink for inkjet recording characterized by using a polymer dispersant obtained by subjecting a sulfonated product obtained by sulfonating an aromatic compound containing an aromatic compound represented by the formula to a formalin condensation and then neutralizing the sulfonated product. The above object has been achieved by providing

[0008]

Embedded image

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

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The ink jet recording ink of the present invention comprises a water-insoluble or poorly water-soluble coloring material, a dispersant and a water-soluble medium. The ink for inkjet recording of the present invention is characterized in that a sulfonated product obtained by sulfonating aromatic compounds including the aromatic compounds represented by the above formulas (I) and (II) as for the dispersant is formalin. It is characterized by using a polymer dispersant obtained by condensation and then neutralization.

The above-mentioned polymer dispersant will be described in detail. The aromatic compound used as a raw material of the polymer dispersant is an aromatic compound represented by the above formula (I), that is, an alkylnaphthalene, and an aromatic compound represented by the above formula (II) An aromatic compound represented by (hereinafter, referred to as
This aromatic compound is referred to as “phenolic compound”). Hereinafter, the alkyl naphthalene and the phenol compound will be described.

First, the alkylnaphthalene will be described. In the above formula (I), R ₁ and R ₂ are the same or different hydrogen atoms or alkyl groups having 1 to 5 carbon atoms, as described above. It is a methyl group, an ethyl group, a propyl group or a butyl group, more preferably a methyl group or a butyl group, and particularly preferably a methyl group.
In the formula (I), when _one of R ₁ and R ₂ is a hydrogen atom, that is, when the alkylnaphthalene is a monoalkylnaphthalene, the alkyl group is located at any of the α-position and the β-position of the naphthalene ring. They may be combined. On the other hand, in the above formula (I), when both R ₁ and R ₂ are an alkyl group, that is, when the alkylnaphthalene is a dialkylnaphthalene, the bonding position of the two alkyl groups is not particularly limited, but is preferably 2,6-position, 1,3-position, 1,6-
And the 1,8-position.

In the present invention, the above-mentioned alkylnaphthalene may be used alone or as a mixture within the range represented by the above formula (I).

Preferred examples of the alkylnaphthalene include dimethylnaphthalene, methylnaphthalene and butylnaphthalene. Further, diethyl naphthalene and dibutyl naphthalene are also preferably used.

Next, the phenolic compound will be described. In the above formula (II), R ₃ and R ₄ are the same or different hydrogen atoms or alkyl groups having 1 to 5 carbon atoms, as described above. Preferably it is a methyl group or an ethyl group. In the formula (II), when one of R ₃ and R ₄ is a hydrogen atom, that is, when the phenolic compound is a monoalkylphenol, the alkyl group is any one of the ortho, meta and para positions of the benzene ring. May be bonded. On the other hand, in the above formula (II), when both R ₃ and R ₄ are alkyl groups, that is, when the phenolic compound is a dialkylphenol, the bonding position of the two alkyl groups is not particularly limited, but is preferably Is 2,6-position, 3,5
Attached to the − position.

In the present invention, the phenolic compound may be used alone or as a mixture within the range represented by the above formula (II).

Particularly preferably used in the present invention as the phenolic compound are cresol, xylenol, phenol and ethylphenol. Also, diethylphenol is preferably used.

There is no particular limitation on the proportion of the above-mentioned alkylnaphthalene and the above-mentioned phenolic compound, but from the viewpoint of the high-temperature stability of the dispersion, the proportion of the above-mentioned alkylnaphthalene and the above-mentioned phenolic compound (the former: the latter) Is preferably 1: 3 to 1:15 by weight ratio.

The aromatic compounds may be composed of only the alkylnaphthalene and the phenol compound, or may be composed of the alkylnaphthalene and the phenol compound and another polynuclear aromatic compound. In this specification, "polynuclear aromatic compound"
A) a compound in which two or more aromatic rings or hetero rings share two or more carbon atoms to form a condensed ring and a derivative thereof, and b) two or more compounds In which an aromatic ring or a heterocyclic ring is directly bonded or bonded through an alkylene group and derivatives thereof, but excluding naphthalene.

Examples of the polynuclear aromatic compound include the compounds of the above a), such as anthracene, phenanthrene,
Examples include pyrene, acenaphthene, indene, fluorancene, chrysene, benzofluorancene, benzopyrene, perylene and benzoperylene, and mono-, di- or trialkyl-substituted products thereof. Examples of the compound b) include fluorene, diphenyl and dibenzofuran.

Examples of the compound preferably used as the polynuclear aromatic compound include at least one selected from anthracene, phenanthrene, pyrene, acenaphthene and fluorene.

The aromatic compounds may be composed of the alkylnaphthalene and the phenolic compound, and the other polynuclear aromatic compounds and / or other mononuclear aromatic compounds. Examples of the mononuclear aromatic compound include benzene, toluene, xylene, tetralin and the like.

To prepare the above polymer dispersant, first,
The aromatic compounds are sulfonated with a sulfonating agent, for example, concentrated sulfuric acid or fuming sulfuric acid to obtain a sulfonated product.
The sulfonation can be carried out by a known method. For example, when concentrated sulfuric acid is used as the sulfonating agent, the aromatic compound is charged into a reactor equipped with a stirrer, and charged to
Sulfonation can be carried out by gradually adding concentrated sulfuric acid at a temperature of 0 ° 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 formalin condensate obtained by the formalin condensation is then neutralized with a predetermined neutralizing agent, whereby the polymer dispersant is obtained. For the neutralization, for example, a method known as liming soda tion is used. That is, a method is used in which calcium hydroxide or calcium carbonate is added for neutralization, the resulting calcium sulfate is separated by filtration, and a neutralized product is obtained by adding sodium carbonate, ammonium carbonate, potassium carbonate or the like to the filtrate. 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 polymer dispersant thus obtained preferably has a weight average molecular weight of 2,000 to 50,000 from the viewpoint of ink viscosity and 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 polymer dispersant,
The dispersibility of the coloring material is extremely improved, and the coloring material becomes fine particles.
At the same time, aggregation and sedimentation associated therewith are effectively prevented. Ma
In addition, since the coloring material becomes fine,
The adhesive force (fixing property) to the recording member is improved. The present invention
The degree of atomization in ink jet recording ink
200 g in size with a 5 μm membrane filter
Filtration at constant pressure (3.5 kg / cm ^Two)
The filtration rate does not change and the pore size is 1.2 μm.
200 g of ink was filtered at a constant pressure with a Blen filter (3.5
kg / cm^Two) Even if there is a decrease in filtration speed
With a very high degree of micronization that the whole amount passes through
is there.

The polymer dispersant is preferably added to the ink for ink jet recording of the present invention in an amount of 0.8 to 10% by weight, more preferably 0.8 to 7% by weight, and still more preferably 1.2 to 10% by weight. 5% by weight is blended. If the amount of the polymer dispersant is less than 0.8% by weight, depending on the type of the coloring material, the ink cannot be prepared at the stage of preparing the ink,
Alternatively, even if the ink can be prepared, the intended long-term storage stability, environmental stability, and abrasion resistance may not be exhibited in the ink. When the ink content exceeds 10% by weight, the dispersant adsorbs to the coloring material. May be inhibited, so that it is more preferably 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 ink jet recording ink of the present invention will be described. As a coloring material to be incorporated in the ink for ink jet recording of the present invention, a water-insoluble or poorly water-soluble coloring material is used. Here, the water-insoluble or poorly water-soluble colorant means various pigments, disperse dyes, oil-soluble dyes, and the like. In this specification,
"Pigment" refers to a dye that is insoluble or hardly soluble in water and an organic solvent, and "disperse dye" refers to a dye that is insoluble or hardly soluble in water and is dissolved in a water-dispersed state close to a colloid. The term "oil-soluble dye" refers to a dye that is not water-soluble and is soluble in mineral oils, fats and oils (Chemical Dictionary, edited by Kyoritsu Shuppan Co., Ltd.).

As the above pigment, for example, azo lake,
Azo pigments such as insoluble azo pigments, condensed azo pigments, chelate azo pigments, and polycyclic pigments such as phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthaloni pigments, Dye lakes such as basic dye lakes and acid dye lakes; organic pigments such as nitro pigments, nitroso pigments, aniline black and daylight fluorescent pigments; and inorganic pigments such as titanium oxide, iron oxide and carbon black. Can be used. In addition, any pigment that is not described in the color index can be used as long as it can be dispersed in the aqueous phase. Further, those obtained by subjecting the above pigment to a surface treatment with a surfactant, a polymer dispersant or the like, or graft carbon, etc., can of course be used. Among the above pigments, it is particularly preferable to use azo pigments, phthalocyanine pigments, anthraquinone pigments, and carbon black pigments.

Examples of the disperse dye include C.I. I.
Disperse Yellow 5, 42, 54, 64, 79,
82, 83, 93, 99, 100, 119, 122, 1
24, 126, 160, 184: 1, 186, 198,
199, 201, 204, 224 and 237; I.
Disperse Orange 13, 29, 31: 1, 33,
49, 54, 55, 66, 73, 118, 119 and 1
63; I. Disperse Red 54, 60, 7
2, 73, 86, 88, 91, 92, 93, 111, 1
26, 127, 134, 135, 143, 145, 15
2,153,154,159,164,167: 1,1
77, 181, 204, 206, 207, 221, 23
9, 240, 258, 277, 278, 283, 31
1, 323, 343, 348, 356 and 362;
I. Disperse Violet 31, 33; I.
Disperse Blue 36, 56, 60, 73, 87,
113, 128, 143, 148, 154, 158, 1
65, 165: 1, 165: 2, 176, 183, 18
5, 197, 198, 201, 214, 224, 22
5, 257, 266, 267, 287, 354, 35
8, 365 and 368; and C.I. I. Disperse
Greens 6: 1 and 9 can be used.

Examples of the above oil-soluble dyes include C.I.
I. Solvent Black 3, 7, 27, 29 and 3
4; I. Solvent Yellow 14, 16, 19,
21, 25, 29, 30, 56, 82, 93 and 16
2; I. Solvent Red 1, 3, 8, 18, 1
9, 24, 27, 43, 49, 51, 72, 73, 8
3, 109, 112, 117, 122, 132, 138
And 218; I. Solvent Violet 3;
C. I. Solvent Blue 2, 11, 25, 35, 3
8, 63, 67, 70, 95 and 117; I. Solvent Green 3 and 7; and C.I. I. Solvent Orange 2 or the like 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 depends on the desired long-term storage stability, environmental stability, abrasion resistance and filterability in the preparation stage. 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 60 nm.

In particular, the above carbon black has a BE
Preferably T specific surface area of 20 to 500 m ² / g, and further preferably from 50 to 500 m ² / g.
As the carbon black, for example, COLUMBIA
N R3500, R1100, R1080, R104
0, R1255, R780, R450, R14, RH2
0, BLACK PEARLIS 880, 280, 1
30, 480, L, REGAL250, 500R, C
color Black FW18, S170, S16
0, FW1, Printex U, V, 60, 40
(Made by DEXA), # 2650, # 1000, # 970,
MA77, MA100, M230 and the like can be used.

The water-insoluble or hardly water-soluble coloring material is preferably used in the ink for ink jet recording of the present invention in an amount of from 2 to 1.
0% by weight, more preferably 2 to 7% by weight, more preferably 3 to 5% by weight. If the amount of the water-insoluble or poorly water-soluble coloring material is less than 2% by weight, not only a good dispersion cannot be obtained at the ink preparation stage, but also the print density is low and the efficiency at the ink preparation stage is low. When the content exceeds 10% by weight, the effect is saturated in terms of print density, so that the content is preferably within the above range.

The amount of the water-insoluble or poorly water-soluble colorant is determined by the weight ratio of the colorant to the polymer dispersant (the former / the latter) in relation to the amount of the polymer dispersant.
Is 100/200 to 100/4 (especially, 100/100
１００100/10, especially 100/80 to 100/4
0) is preferable in terms of long-term storage stability and environmental stability as an ink.

The water-soluble medium incorporated in the ink for ink-jet recording 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, glycols such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol and tetraethylene 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 carbitol acetate, diethyl carbitol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, And ethers of polyhydric alcohols such as propylene glycol monomethyl ether; acetates; thiodiglycol; N-methyl-2-pyrrolidone;
-Nitrogen-containing compounds such as dimethylimidazolidinone, formamide and dimethylformamide; one or more of dimethyl sulfoxide can be used. These water-soluble solvents are preferably incorporated in the ink of the present invention in an amount of 3 to 30% by weight, more preferably 5 to 10% by weight. The amount of the water-soluble medium (the total amount of water and water-soluble solvent) is preferably from 80 to 97.2% by weight, more preferably from 86 to 9 in terms of dispersion efficiency.
It is 7.2% by weight, more preferably 90 to 95.8% by weight.

The ink jet recording ink of the present invention may further contain optional components, if necessary, in addition to the above essential components. As such an optional component, for example, the average particle size of the primary particles is preferably 5 to 600 nm,
More preferably, fine particles of 10 to 100 nm are used. Incorporation of such fine particles is preferable because the print density of the ink is improved. The fine particles are not particularly limited, for example, silicon oxide,
Inorganic substances such as titanium oxide and aluminum oxide, silicon-based resins, water-insoluble polymers such as polyamide-based resins and fluorine-based resins, and the like, more preferably silicon oxide, at least one selected from titanium oxide and aluminum oxide, particularly preferably Is silicon oxide. These fine particles can be used alone or in combination of two or more. The fine particles are preferably blended in the ink for inkjet recording of the present invention in an amount of 0.2 to 10% by weight, more preferably 0.5 to 7% by weight. The average particle size of the primary particles of the above fine particles can be measured by CPS Disc Centrifuge (trade name) of Central Science and Technology Corporation. In order to facilitate the handling of the fine particles, a dispersant that does not adversely affect the properties of the ink may be used in preparing the ink.

As the fine particles of silicon oxide, those having either a hydrophilic surface or a hydrophobic surface can be used, but those having a hydrophilic surface are more preferable in terms of ease of blending. For example, Aerosil 50, 130, 200, 200V, 200 manufactured by Japan Aerosil Co., Ltd.
CF, 200FAD, 300, 300CF, 380 (above, hydrophilic), R972, R972CF, R974, R
X200, RY200, R202, R805, R812
(Above, hydrophobic), OX50, TT600, MOX8
0, MOX170 and COK84 (all hydrophilic) (all trade names), Nissan Chemical Snowtex XS,
O, OL, XS, 30, 20L, C, UP, YL, Z
L, O-40 (all are trade names) and the like can be used. As the fine particles of titanium oxide, those having either a hydrophilic surface or a hydrophobic surface can be used, but those having a hydrophilic surface are more preferable in terms of ease of blending. For example, Aerosil T805 (hydrophobic) and P25 (hydrophilic) (all trade names) manufactured by Nippon Aerosil Co., Ltd. can be used. As the fine particles of aluminum oxide, those having either a hydrophilic surface or a hydrophobic surface can be used, but those having a hydrophilic surface are more preferable in terms of ease of blending. For example, Aerosil Al2O3 manufactured by Japan Aerosil Co., Ltd.
C (hydrophilic) (trade name) or the like can be used. Other inorganic substances include, for example, colloidal alumina polyallol # 10 and # 25, manufactured by Taki Kagaku Co., Ltd., titanium oxide sol, silica fine particles, zirconia colloidal sol, zirconia powder, NS-O manufactured by Nippon Shokubai Kagaku Co., Ltd. , NS
-3Y, NS-8Y, SILF manufactured by Shin-Etsu Chemical Co., Ltd.
IX (all trade names) can be used.

The polymer constituting the water-insoluble polymer particles is not particularly limited, but is not swelled by water or a water-soluble organic solvent, or even if swelled, the particle size after swelling is 1% of the particle size before swelling. It is preferred to use a polymer that is up to 1.2 times. Such polymers are not particularly limited, for example, benzoguanamine,
Melamine-based resins such as benzoguanamine / melamine and methacrylate-based resins, and the aforementioned silicon-based resins, fluorine-based resins, and polyamide-based resins are exemplified. Examples of the fluorine-based resin include, for example, NEOFLON FEP, ND-1, ND-2, and N, manufactured by Daikin Industries, Ltd.
D-4, Lubron LDW-40, Daiel GL-15
2, GL-252, GLS-213, GLS-223,
GLS-213D, Dickguard F-52S, F-70, F-18, F-9 manufactured by Dainippon Ink and Chemicals, Inc.
0, F-90N, FS-90H, FS-1, F-40
0, CP, CP-2, Fluon dispersion AD1, AD639, AD936, Asahigard AG-422, AG-423, AG-490, AG manufactured by Asahi Glass Co., Ltd.
-460X, AG-710, LS-317, AG-41
5, AG-930, AG-970, LS-6015, A
G-780, AG-850, AG-530, AG-55
0, Fluororesin dispersions 30-J, 3443-J, 41- manufactured by DuPont-Mitsui Fluorochemicals Co., Ltd.
J, 42-J, 3170-J, K20-J, 120-J
Etc. can be used. As the silicone resin, for example, DC8 manufactured by Dow Corning Asia Co., Ltd.
4, DC85, TEX10 manufactured by Toshiba Silicone Co., Ltd.
0, TEX101, TEX102, TEX103, TE
X104, YMR7212, TSW831, TEX15
0, TEX151, TEX152, TEX153, TE
X171, TEX172, UM-110, UM-12
0, Tospearl 105, 120, 130, 145, 24
0, Polon MR, MG, manufactured by Shin-Etsu Chemical Co., Ltd.
MWS, MF-16, MK-206, MF-5, MF-
7, MF-17, MF-14, MF-14EC, MF-
14D, MF-11B, MF-18, MF-20, MF
-23, MN, MNS, MF-2A, MF-10, MF
-22, MF-33A, MF-40, C, MF-28,
Softener sill 10 or the like can be used.

It is also preferable that the inkjet recording ink of the present invention contains polyethylene glycol (PEG). It is preferable to mix polyethylene glycol because intermittent ejection of the ink is improved. Polyethylene glycol preferably has a molecular weight of 200 to 6000, and more preferably 200 to 4000, from the viewpoint of further improving the intermittent ejection property of the ink. Polyethylene glycol is preferably contained in the ink for inkjet recording of the present invention in an amount of 3 to 10% by weight.
And more preferably 3 to 5% by weight.

It is also preferable that the ink jet recording ink of the present invention contains at least one surfactant selected from nonionic and anionic surfactants. By adding such a surfactant, it is possible to stabilize the non-coloring material fine particles (for example, the above-mentioned inorganic fine particles and water-insoluble polymer fine particles) in the ink and to control the surface tension of the ink, which is preferable. . Such a surfactant is preferably incorporated in the inkjet recording ink of the present invention in an amount of 0.01 to 3% by weight, more preferably 0.05 to 1% by weight. Examples of the nonionic surfactant include 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. And a surfactant selected from the group consisting of (poly) glycosides.
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. Examples of the anionic surfactant include an alkyl sulfonate, an alkylbenzene sulfonate, an alkyl naphthalene sulfonate, an alkane or olefin sulfonate, an alkyl sulfate, a polyoxyethylene alkyl or an alkyl aryl ether sulfate, and an alkyl sulfonate. Surfactants selected from the group consisting of phosphates, alkyl diphenyl ether disulfonates, ether carboxylates, alkyl sulfosuccinates, α-sulfo fatty acid esters, and fatty acid salts, condensates of higher fatty acids and amino acids, naphthenates Etc. can be used. Anionic surfactants preferably used include alkylbenzene sulfonates (particularly linear alkyl), alkanes or olefin sulfonates (particularly secondary alkane sulfonates, α-olefin sulfonates), alkyl sulfates Polyoxyethylene alkyl or alkyl aryl ether sulfates (especially polyoxyethylene alkyl ether sulfates), alkyl phosphates (especially monoalkyl), ether carboxylates,
A surfactant selected from the group consisting of alkylsulfosuccinates, α-sulfofatty acid esters, and fatty acid salts, more preferably alkylsulfonates, alkylbenzenesulfonates (particularly those having linear alkyl groups), Examples include ethylene alkyl or alkyl aryl ether sulfates (particularly polyoxyethylene alkyl ether sulfates), alkyl sulfates, and alkyl sulfosuccinates. Among them, polyoxyethylene alkyl or alkyl aryl ether sulfate and alkyl sulfosuccinate are preferred. These can be used alone or in combination of two or more.

The ink jet recording ink of the present invention further includes various surfactants (cationic and zwitterionic surfactants) which can further enhance the dispersibility of the coloring material, an antifoaming agent such as a silicone compound, Fungicides such as methylphenol compounds, chelating agents such as EDTA, oxygen absorbers such as sulfites, benzotriazoles, benzophenones,
An ultraviolet absorber such as hydroxybenzoate, salicylate and cyanoacrylate may be contained. These optional components are preferably blended in the ink for inkjet recording of the present invention in an amount of 1 to 5% by weight (particularly 2 to 3% by weight).

The method for preparing the ink jet recording ink of the present invention is not particularly limited, but is preferably prepared by the method described below. That is, first, (1) a water-insoluble or hardly water-soluble coloring material, the polymer dispersant, the water-soluble medium, and optional components such as the fine particles as needed are stirred with a dissolver to prepare a preliminary dispersion, ,
(2) Dispersing the preliminary dispersion with a wet medium mill such as a Dyno mill to obtain a colorant dispersion, and (3) dispersing the colorant dispersion with at least water, preferably purified water (ion-exchanged water). By diluting, the above ink is obtained.

The above-mentioned preparation method will be described in detail. In the above 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 5 hours (particularly 1.5 to 5 hours). In the above preparation method, the above (1)
A circulation operation method in which step (2) and step (2) are repeated a predetermined number of times may be used. The preferred concentration of each component in the colorant dispersion liquid thus obtained is such that the concentration of the colorant is 5 to 40% by weight, the concentration of the polymer dispersant is 2 to 40% by weight, When the concentration of the aqueous medium is 2
0 to 93% by weight. Next, in the step (3), the color material dispersion is stirred and diluted using a dissolver or the like such that the concentration of each component becomes the final concentration. After dilution of the colorant dispersion, it is preferable to remove coarse particles (preferably 2 μm or more, more preferably 1 μm or more) using a membrane filter or the like. This is preferable because ink that does not cause clogging can be obtained.

The preferred range of the concentration of each component in the ink for ink jet recording thus obtained is as described below. The colorant: 2 to 10% by weight, particularly 3 to 5% by weight The polymer dispersant: 0.8 to 10% by weight, particularly 1.2 to 10% by weight
5% by weight water: 80 to 97.2% by weight, especially 90 to 95.8% by weight

The ink-jet recording ink of the present invention comprises:
Any printer can be used as long as it is a printer using an ink jet recording method, that is, a recording method in which ink is ejected from a nozzle to a recording member as ink droplets to perform recording. 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 inkjet recording of the present invention is particularly suitable for use in the case of using a non-permeable recording member such as a plastic sheet, for which it has been conventionally difficult to enhance the fixability, by the action of the polymer dispersant. Can be formed into fine particles, exhibiting extremely high fixing properties, and a printed image having high scratch resistance can be obtained.
When plain paper is used as the recording member,
By applying an aqueous solution of polyester emulsion, acrylic, silicone emulsion, PVA or the like on the printed image after printing, the scratch resistance of the printed image can be further enhanced.

[0050]

EXAMPLES The effectiveness of the ink for ink-jet recording and the ink-jet recording method of the present invention will be illustrated below with reference to examples. 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 The following components were mixed with purified water at the following compounding ratio, and stirred using a dissolver (high-speed / high-shear-force dissolver, manufactured by Shinmaru Enterprises) (temperature: 30 ° C., Time: 15 minutes, rotation speed: 600
0 rpm) and a preliminary dispersion having a solid content of 20% was prepared.・ 100 parts of carbon black (acid) (FW18, manufactured by Degussa, BET specific surface area: 260 m ² / g, average particle size of primary particles: 15 nm) ・ [2,6-dimethylnaphthalene and 2,6-xylenol] sulfonate 60 parts of formalin condensate [Polymer dispersant, weight average molecular weight: 13000, weight ratio of 2,6-dimethylnaphthalene to 2,6-xylenol (former: latter) = 1: 8] polyethylene glycol (molecular weight: 200) 100 parts ・ Silicon dioxide 20 parts [Aerosil 200CF (trade name) manufactured by Japan Aerosil Co., Ltd., average particle size of primary particles: 12 nm] ・ Sodium dialkylsulfosuccinate 10 parts [Anionic surfactant, Kao Corporation Perex OT-P (trade name)] Next, the above preliminary dispersion 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. Was prepared. Then
Purified water was added to the colorant dispersion so that the concentration of carbon black was 5%, and the colorant dispersion was stirred and diluted using a dissolver. Further, the mixture was filtered through a 1.2-micron filter to prepare an ink for inkjet recording.

[Example 2] [2,6-
Instead of the formalin condensate of dimethylnaphthalene and 2,6-xylenol] sulfonate, a formalin condensate of [1,3-dimethylnaphthalene and o-cresol] sulfonate [weight average molecular weight: 14,000, 1,3-
Using a weight ratio of dimethylnaphthalene to o-cresol (former: latter) = 1: 8], titanium dioxide [Aerosil P25 manufactured by Nippon Aerosil Co., Ltd.] is used instead of silicon dioxide.
(Trade name), average particle size of primary particles: 21 nm], and an ink for inkjet recording was prepared in the same manner as in Example 1.

Example 3 [2,6-
Instead of a formalin condensate of dimethylnaphthalene and 2,6-xylenol] sulfonic acid salt, a formalin condensate of [1,6-dibutylnaphthalene and 3,5-xylenol] sulfonic acid salt [weight average molecular weight: 14,000,
Using a weight ratio of 1,6-dibutylnaphthalene to 3,5-xylenol (former: latter) = 1: 5], aluminum oxide [Aerosil Al2O3C (trade name) manufactured by Nippon Aerosil Co., Ltd.] is used instead of silicon dioxide. , An average particle size of primary particles: 13 nm], to prepare an ink for inkjet recording in the same manner as in Example 1.

Example 4 [2,6-
Instead of the formalin condensate of dimethylnaphthalene and 2,6-xylenol] sulfonate, a formalin condensate of [1,8-dimethylnaphthalene and m-cresol] sulfonate [weight average molecular weight: 15,000, 1,8-
Weight ratio of dimethylnaphthalene to m-cresol (former: latter) = 1: 12] and using polymer fine particle eposter MA (MA03W manufactured by Nippon Shokubai Co., Ltd.) instead of silicon dioxide.
(Trade name), average particle size of primary particles: 40 nm], and an ink for inkjet recording was prepared in the same manner as in Example 1.

Example 5 [2,6-
Instead of a formalin condensate of dimethylnaphthalene and 2,6-xylenol] sulfonate, a formalin condensate of [2,6-diethylnaphthalene and 2,5-xylenol] sulfonate [weight average molecular weight: 14,000,
An ink jet recording ink was prepared in the same manner as in Example 1, except that the weight ratio of 2,6-diethylnaphthalene to 2,5-xylenol (former: latter) = 1: 6] was used.

[Example 6] [2,6-
Instead of the formalin condensate of dimethylnaphthalene and 2,6-xylenol] sulfonate, a formalin condensate of [2,3-dimethylnaphthalene and 2,4-diethylphenol] sulfonate [weight average molecular weight: 1500
An ink for inkjet recording was prepared in the same manner as in Example 1 except that the weight ratio of 0,2,3-dimethylnaphthalene to 2,4-diethylphenol (former: latter) = 1: 10] was used.

Example 7 [2,6-
Instead of the formalin condensate of dimethylnaphthalene and 2,6-xylenol] sulfonate, a formalin condensate of [1,5-dimethylnaphthalene and 3,5-diethylphenol] sulfonate [weight average molecular weight: 1600
An ink for inkjet recording was prepared in the same manner as in Example 1 except that the weight ratio of 0,1,5-methylnaphthalene to 3,5-diethylphenol (former: latter) = 1: 13] was used.

[Comparative Example 1] [2,6-
JP-A-8-291 instead of the formalin condensate of dimethylnaphthalene and 2,6-xylenol] sulfonate
[Phenol and naphthalene] used in Example 2 of JP-A-266 (see column 7, lines 25 to 26 of the publication)
Example 1 except that a formalin condensate of sodium sulfonate (weight average molecular weight: 13000, weight ratio of phenol to naphthalene (former: latter) = 50: 50) was used.
In the same manner as described above, an ink jet recording ink was prepared.

[Comparative Example 2] [2,6-
JP-A-8-333 instead of the formalin condensate of dimethylnaphthalene and 2,6-xylenol] sulfonate
No. 531, Example 1 (columns 13 to 36 of the publication)
Condensate of sodium naphthalene sulfonate (weight average molecular weight: 2600)
The ink for inkjet recording was prepared in the same manner as in Example 1 except that aluminum oxide (Aerosil Al2O3C (trade name, manufactured by Nippon Aerosil Co., Ltd., average particle size of primary particles: 13 nm)) was used instead of silicon dioxide. Prepared.

Comparative Example 3 An ink for inkjet recording was prepared in the same manner as in Comparative Example 2 except that aluminum oxide was not used.

[Comparative Example 4] [2,6-
(Styrene-acrylic acid) copolymer (weight average molecular weight: 18000) instead of the formalin condensate of dimethylnaphthalene and 2,6-xylenol] sulfonic acid salt, and an anionic surfactant (sodium dialkyl sulfosuccinate); Example 1 except that silicon dioxide was not used
In the same manner as described above, an ink jet recording ink was prepared.

[Evaluation of Performance] In order to evaluate the performance of the inks obtained in Examples and Comparative Examples, long-term storage stability, environmental stability, bleeding, water resistance, scratch resistance and print density were measured by the following methods. did. Table 1 shows the results.

<Long-term storage stability> Immediately after preparation and at 80 ° C.
The viscosity of the ink stored for 120 hours was measured according to the following measurement method, and the long-term storage stability based on the change in viscosity was evaluated according to the following evaluation criteria.

The viscosity was measured at 20 ° C. using an ELD type viscometer (manufactured by Tokimec). The measurement was performed at 10 rpm or 50 rpm one minute after the preliminary rotation.

Evaluation criteria : Viscosity rise is 1 cP or less ··· · Viscosity rise exceeds 1 cP and 2 cP or less ······ Viscosity rise exceeds 2 cP ···・ ・ ・ ・ ・ ・ ・ ×

<Environmental Stability> After the obtained ink was repeatedly stored for 10 cycles under the following storage conditions as one cycle, environmental stability based on a change in viscosity was evaluated on the same basis as in the case of the above long-term storage stability. . 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]

<Bleeding> Alphanumeric characters are printed on recycled paper for PPC (manufactured by Nippon Kabushiki Kaisha, Ltd.), and after standing for one hour or more, the sharpness of the characters and the whisker-like shape generated from the characters are observed under a microscope and visually. The degree of bleeding was evaluated according to the following criteria.・ Character is sharp and has no bleeding ・ ・ ・ ○ ・ Character is not sharp and bleeding occurs a little △ ・ ・ Character is not sharp and bleeding is frequent ×

<Waterfastness> Solid printing was performed on recycled paper for PPC (manufactured by Nippon Kabushiki Kaisha, Ltd.), and after standing for 1 hour or more, it was immersed vertically in still water for 10 seconds and pulled up vertically as it was. After air drying in a room, the optical density of the white portion where no printing was performed was measured with a Macbeth densitometer RD918 (manufactured by Macbeth), and the water resistance was evaluated based on the following criteria.・ Optical density change is 0.1 or less ・ ・ ・ ○ ・ Optical density change is more than 0.1 and less than 0.5 ・ ・ ・ △ ・ Optical density change is 0.5 or more ・ ・ ・ ×

<Scratch Resistance> Printing was performed on a boehmite-containing OHP sheet (boehmite-based OHP sheet) widely used in plain paper and commercial OHP sheets, 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. No, but the surroundings of the printed image may be stained ........ △ ・ If the printed image is rubbed with a nail, the printed image will be lost.

<Print Density> Printing was performed by using solid paper using recycled paper for PPC [manufactured by Nippon Kaishi Paper Co., Ltd.], allowed to dry naturally in a room for 24 hours, and then measuring the optical density using a Macbeth densitometer. It was measured with RD918 (manufactured by Macbeth) and evaluated according to the following criteria. · Optical density is 1.3 or more ··· · Optical density is less than 1.3 and 1.1 or more · · · Optical density is less than 1.1 · ×

[0071]

[Table 1]

As is clear from the results shown in Table 1, the inks for ink-jet recording of the present invention (Examples 1 to 7) containing a specific polymer dispersant were compared with the inks of Comparative Examples 1 to 4. It turns out that it is excellent in long-term storage stability and environmental stability. In addition, it can be seen that the ink jet recording ink of the present invention (Examples 1 to 7) has low bleeding, water resistance and abrasion resistance required for the ink jet ink, and high print density.

[0073]

According to the present invention, an ink for inkjet recording having excellent long-term storage stability and environmental stability can be obtained. Further, according to the present invention, an ink jet recording ink is obtained which is excellent in fixability particularly to a non-permeable recording member and can obtain a printed matter having high scratch resistance. Further, according to the present invention, an ink for inkjet recording which can obtain a printed matter having low bleeding property and high print density can be obtained.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigemi Wakabayashi 2606 Kabane-cho, Akaga-cho, Haga-gun, Tochigi Prefecture At Kao Co., Ltd.

Claims (8)

[Claims] 1. An ink jet recording ink comprising a water-insoluble or poorly water-soluble colorant, a dispersant and a water-soluble medium, wherein the dispersant is represented by the following formula (I) or (II): An ink for inkjet recording, comprising using a polymer dispersant obtained by formalin-condensing a sulfonated product obtained by sulfonating an aromatic compound containing an aromatic compound and then neutralizing the sulfonated product. Embedded image 2. The aromatic compound represented by the formula (I) is dimethylnaphthalene, methylnaphthalene or butylnaphthalene, and the aromatic compound represented by the formula (II) is cresol, xylenol, phenol or ethyl. Phenol, the ratio of the aromatic compound represented by the formula (I) to the aromatic compound represented by the formula (II) (the former:
2. The ink jet recording ink according to claim 1, wherein (latter) is 1: 3 to 1:15 by weight. 3. The concentration of the colorant is 2 to 10% by weight, the concentration of the polymer dispersant is 0.8 to 10% by weight, and the concentration of the water-soluble medium is 80 to 97.2% by weight. %. 3. The ink for inkjet recording according to claim 1, wherein 4. The ink jet recording ink according to claim 1, further comprising fine particles having an average primary particle size of 5 to 600 nm. 5. The ink jet recording ink according to claim 4, wherein the fine particles are at least one kind of fine particles selected from silicon oxide, titanium oxide and aluminum oxide. 6. The ink for inkjet recording according to claim 1, further comprising polyethylene glycol. 7. The ink jet recording ink according to claim 1, further comprising at least one surfactant selected from nonionic and anionic surfactants. 8. An ink jet recording method, wherein the ink jet recording ink according to claim 1 is ejected as ink droplets from a nozzle to a recording member to perform recording.