JP2015110793A - Ink for inkjet recording and ink set for inkjet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink for inkjet recording having excellent clogging recovery property and capable of suppressing generation of bleeding and beading.SOLUTION: The ink for inkjet recording comprises an alkane diol having poor water solubility, a resin, and a coloring material, in which the content of the coloring material is 1 to 3 mass% with respect to the whole mass of the ink. The ink has a surface tension of 21 to 25 mN/m and shows a thixotropy index (TI) represented by formula (1):TI=η(1 s)/η(1000 s) of 2 to 110 when the mass of the ink is decreased to 40 mass% by vaporization with respect to the whole mass of the ink before vaporization.

Description

The present invention relates to an inkjet recording ink and an inkjet recording ink set.

The ink jet recording method is a printing method in which printing is performed by causing ink droplets to fly and adhere to a recording medium such as paper. Due to recent advances in inkjet recording technology, inkjet recording methods have been used in the field of high-definition printing that has been realized only by silver salt photography and offset printing. Along with this, high glossy recording media comparable to photographic paper and art paper used in the field of silver salt photography and offset printing, so-called special paper, is used for inkjet recording, and it is as glossy as silver salt photography. Ink for ink-jet recording that can realize an image having a feeling has been developed. Ink-jet recording inks have been developed that can achieve image quality comparable to silver salt photographs even when plain paper is used.

In recent years, light inks such as light cyan and light magenta have attracted attention in order to obtain an image in which color gradation is expressed more naturally and beautifully.

For example, Patent Document 1 discloses an ink composition for ink jet recording comprising at least a water-based dispersion of pigment, polymer fine particles, a water-soluble organic solvent, and water, wherein the water-based dispersion of the pigment is described above. An ink composition is disclosed in which a pigment is included by a polymer of a polymerizable surfactant having both nonionic and anionic hydrophilic properties and a monomer.

For example, Patent Document 2 contains at least a pigment, a polymer compound A, and a polymer compound B, the polymer compound A is an amphiphilic polymer compound, and the polymer compound B is a glass transition. An inkjet ink is disclosed which is a polymer compound having a point (Tg) of −30 ° C. or higher and 60 ° C. or lower.

For example, Patent Document 3 discloses an ink composition for inkjet recording comprising at least a colorant, water, an alcohol solvent, and a surfactant, and the alcohol solvent includes:
An ink composition containing a slightly water-soluble alkanediol, a water-soluble 1,2-alkanediol, and a dialkylene glycol is disclosed.

JP 2001-123098 A JP 2006-96933 A JP 2009-209338 A

However, any of the techniques disclosed in Patent Documents 1 to 3 can be applied as light ink, among clogging recoverability and occurrence of bleeding and beading.
At least one of them is inferior or has room for improvement.

Accordingly, an object of the present invention is to provide an ink for ink jet recording which is excellent in clogging recovery and can suppress the occurrence of bleeding and beading.

The present inventors have intensively studied to solve the above problems. As a result, the following was found. First, when an ink containing a hardly water-soluble alkanediol and a resin is used for ink jet recording, the ink is dynamic and has a relatively high viscosity when ejected, and the ink is static when landing or adhering to a recording medium. The viscosity was found to be relatively low. And the ink is
Even if the initial viscosity is low, evaporation on the recording medium, that is, volatilization of volatile components proceeds,
It was found that pseudoplastic fluid (described later) is expressed early, and bleeding and bleeding (described later) are effectively suppressed. The ability to keep the initial viscosity low can improve clogging recovery.

In particular, in light ink having a colorant concentration of 1 to 3% by mass, the viscosity increases by containing a hardly water-soluble alkanediol and a resin and controlling the thixotropy index (TI) within a predetermined range. In addition, a pseudoplastic fluid (described later) can be developed. Thus, it has been found that the occurrence of bleeding and bleeding of the light ink can be effectively suppressed.

Ink beading (described later) and bleeding that occurs when recording on a recording medium (especially a low water-absorbing recording medium) reduces the surface tension of the ink and adheres to the recording medium. It has been found that it can be effectively suppressed by suppressing the fluidity of the liquid, that is, by expressing the pseudoplastic fluid on the recording medium. Specifically, it has been found that the above-described effects can be obtained by controlling the surface tension and thixotropy index (TI) of the ink within a predetermined range.

Based on the above findings, the present inventors include a slightly water-soluble alkanediol, a resin, and a coloring material having a predetermined concentration, a surface tension of 21 to 25 mN / m, and the following formula (1): :
TI = η (1 s ⁻¹ ) / η (1000 s ⁻¹ ) (1)
The thixotropy index (TI) at the time of 40 mass% with respect to the total mass before evaporation of the ink represented by The present invention has been completed by finding that it is excellent and can suppress the occurrence of bleeding and beading.

That is, the present invention is as follows.
[1]
An ink for inkjet recording comprising a hardly water-soluble alkanediol, a resin, and a color material, wherein the content of the color material is 1 to 3% by mass relative to the total mass of the ink, and surface tension Is 21 to 25 mN / m, and the thixotropy index (TI) is represented by the following formula (1) when the ink has evaporated to 40% by mass with respect to the total mass before evaporation of the ink: Ink for ink-jet recording, wherein is 2 to 110.
TI = η (1 s ⁻¹ ) / η (1000 s ⁻¹ ) (1)
[2]
The ink for inkjet recording according to [1], wherein the thixotropy index is 4 to 110.
[3]
The resin is at least one of a polyolefin resin and a urethane resin;
The ink for inkjet recording as described in [1] or [2].
[4]
The ink for inkjet recording according to any one of [1] to [3], which has an initial viscosity of 3 to 10 mPa · s.
[5]
[1] to [4] The inkjet recording ink according to any one of [1] to [4] and an inkjet recording ink containing a color material, wherein the content of the color material is 5 to 7 mass based on the total mass of the ink. %, An ink jet recording ink set comprising:

Hereinafter, embodiments for carrying out the present invention will be described in detail. In addition, this invention is not restrict | limited to the following embodiment, A various deformation | transformation can be implemented within the range of the summary.

In this specification, bleeding refers to a state in which, between different colors, one adjacent color oozes out and mixes with the other color, resulting in blurring. The beading means local density spots of similar colors that occur when printing in a single color, and does not mean that the portion of the recording medium surface that is not covered with ink remains. The above “when printing with a single color” means, for example, a single color on a 6-inch square (resulting in a single color being printed, and there are a plurality of types of inks that realize that color). May be printed).

In this specification, the thixotropy index (TI) indicates the degree of thixotropy by taking the ratio of static viscosity to dynamic viscosity. More specifically, the viscosity of the ink at a liquid temperature of 25 ° C. is measured using a dynamic viscoelasticity measuring device HAAKE MARS II (rheometer) 2 for a shear rate of 1 s ⁻¹ and a shear rate of 1000 s ^−1. This is a value obtained by measuring the seed and calculating the expression “viscosity at shear rate of 1 s ⁻¹ / viscosity at shear rate of 1000 s ⁻¹ ” (formula (1) described later). In addition, thixotropy in this specification means thixotropy in a broad sense and is also called pseudoplastic fluid. The pseudoplastic fluid refers to a phenomenon in which the viscosity is lowered by applying force by stirring or shaking while applying high force until force is applied.

In the present specification, the alkanediol and dialkylene glycol may be either linear or branched. Further, water-soluble means that the solubility in water (the amount of solute with respect to 100 g of water) is 10.0 g or more, and poorly water-soluble means that the solubility in water (the amount of solute with respect to 100 g of water) is high. It means less than 1.0 g.

In this specification, “(meth) acrylate” means at least one of acrylate and its corresponding methacrylate, and “(meth) acryl” means at least one of acryl and its corresponding methacryl.

[Ink for inkjet recording]
An ink for inkjet recording according to an embodiment of the present invention includes a sparingly water-soluble alkanediol, a resin, and a color material, and the content of the color material is a total mass (100% by mass) of the ink.
The thixotropy index (TI) at a predetermined time point represented by the following formula (1) is 2 to 110.
TI = η (1 s ⁻¹ ) / η (1000 s ⁻¹ ) (1)
In the present specification, “total mass of ink” means the total mass (100 mass%) of ink before evaporation of the ink components, unless otherwise specified.

Here, the significance of TI in the present embodiment will be described. Assuming ink droplets that land on and adhere to the recording medium, if the static viscosity is large, the ink droplets are difficult to move, and bleeding and beading are unlikely to occur.
Further, if both the static viscosity and the dynamic viscosity are large, it is difficult to perform ink jetting. On the other hand, if both the static viscosity and the dynamic viscosity are small, ink jet can be stably performed even at a discharge frequency of 10 kHz or more, but bleeding and beading are likely to occur for the above reasons.

Accordingly, the present inventors can solve the above-mentioned problems with ink for ink jet recording that can perform ink jet because of its low dynamic viscosity, and that is difficult to move while attached to a recording medium because of its high static viscosity. I found out. It was also found that the ink jet recording ink as described above can be obtained by imparting suitable thixotropy characteristics to the ink jet recording ink, that is, by setting the TI within the predetermined numerical range.

Furthermore, an ink droplet of about 1 to 100 pL has a larger surface area ratio per unit volume than an ink droplet of the order of mL to L, thereby increasing the drying speed. for that reason,
Desirable physical properties of the ink droplets for ink jet recording attached to the recording medium need to be defined in a state of being dried to some extent. In view of this, the present embodiment employs the TI at the point when the ink has evaporated to 40 mass% with respect to the total mass before the ink has evaporated.
The “TI at the time when the ink has evaporated to 40% by mass with respect to the total mass before evaporation of the ink” means that the ink is up to 40% by mass with respect to the total mass (100% by mass) before evaporation of the ink. It can be paraphrased as a measured value when evaporates (volatilization of a solvent etc.).

Hereinafter, additives (components) contained in or capable of being contained in the inkjet recording ink (hereinafter also simply referred to as “ink”) will be described.

[Color material]
The ink of this embodiment includes a color material. As the color material, at least one of a pigment and a dye can be used.

(Pigment)
In the present embodiment, by using a pigment as the color material, the light resistance of the ink can be improved. As the pigment, both inorganic pigments and organic pigments can be used.

Inorganic pigments include carbons such as furnace black, lamp black (CI Pigment Black 6), acetylene black, channel black, and carbon black (CI Pigment Black 7), iron oxide, and titanium oxide. can do. In addition, as a commercial item of titanium oxide, for example, CR60-2 (ISHIHARA SANGYO KAIS
HA, LTD.) Product name).

Organic pigments include insoluble azo pigments, condensed azo pigments, azo lakes, chelate azo pigments, etc., phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc. Polycyclic pigments, dye chelates (for example, basic dye type chelates, acidic dye type chelates), dyeing lakes (basic dye type lakes, acid dye type lakes), nitro pigments, nitroso pigments, aniline black (C.I. And CI pigment black 1) and daylight fluorescent pigments.

More specifically, as carbon black used as black ink, No. 23
00, no. 900, MCF88, No. 33, no. 40, no. 45, no. 52,
MA7, MA8, MA100, No. 2200B, etc. (above, Mitsubishi Chemical Corporation (Mitsubishi Che
mical Corporation), Raven 5750, Raven 5250, Raven
5000, Raven 3500, Raven 1255, Raven 700, etc. (above, Columbia Carbon), Rega1 400R, Rega
1 330R, Rega1 660R, Mogul L, Monarch 700, Mo
narch 800, Monarch 880, Monarch 900, Monarc
h 1000, Monarch 1100, Monarch 1300, Monarch
1400 etc. (manufactured by CABOT JAPAN K.K.), Color Black F
W1, Color Black FW2, Color Black FW2V, Colo
r Black FW18, Color Black FW200, Color B1a
ck S150, Color Black S160, Color Black S17
0, Printex 35, Printex U, Printex V, Printex
140U, Special Black 6, Special Black 5, Sp
special Black 4A, Special Black 4 (Degussa (De
gussa)).

Examples of pigments used in white ink include C.I. I. Pigment White 6, 18,
21.

Examples of pigments used in yellow ink include C.I. I. Pigment Yellow 1, 2, 3
4, 5, 6, 7, 10, 11, 12, 13, 14, 16, 17, 24, 34, 35, 3
7, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98
99, 108, 109, 110, 113, 114, 117, 120, 124, 128,
129, 133, 138, 139, 147, 151, 153, 154, 167, 172,
180.

Examples of pigments used in magenta ink include C.I. I. Pigment Red 1, 2, 3,
4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 2
1, 22, 23, 30, 31, 32, 37, 38, 40, 41, 42, 48 (Ca), 4
8 (Mn), 57 (Ca), 57: 1, 88, 112, 114, 122, 123, 144
146, 149, 150, 166, 168, 170, 171, 175, 176, 177
178, 179, 184, 185, 187, 202, 209, 219, 224, 245
Or C.I. I. Pigment violet 19, 23, 32, 33, 36, 38, 43,
50.

Examples of pigments used for cyan ink include C.I. I. Pigment Blue 1, 2, 3, 1
5, 15: 1, 15: 2, 15: 3, 15:34, 15: 4, 16, 18, 22, 25,
60, 65, 66, C.I. I. Bat Blue 4, 60.

Examples of pigments other than magenta, cyan, and yellow include C.I. I. Pigment green 7,10, C.I. I. Pigment brown 3, 5, 25, 26, C.I. I.
Pigment Orange 1, 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 3
8, 40, 43, 63.

  The said pigment may be used individually by 1 type, and may use 2 or more types together.

When the above pigment is used, the average particle size is preferably 300 nm or less, and 50 to 25
0 nm is more preferable. When the average particle diameter is in the above range, the ink can be more excellent in reliability such as ejection stability and dispersion stability, and an image with excellent image quality can be formed. Here, the average particle diameter in the present specification means a particle diameter that becomes 50% cumulative when the total volume of a group of particles is 100%. For example, Photo PAR-III
(Otsuka Electronics Co., Ltd.) can be measured.

(dye)
In the present embodiment, a dye can be used as the color material. The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used.
Examples of the dye include C.I. I. Acid Yellow 17, 23, 42, 44, 79,
142, C.I. I. Acid Red 52, 80, 82, 249, 254, 289, C.I. I
. Acid Blue 9, 45, 249, C.I. I. Acid Black 1, 2, 24, 94
, C.I. I. Food Black 1, 2, C.I. I. Direct yellow 1, 12, 24, 3
3, 50, 55, 58, 86, 132, 142, 144, 173, C.I. I. Direct Red 1,4,9,80,81,225,227, C.I. I. Direct blue 1, 2,
15, 71, 86, 87, 98, 165, 199, 202, C.I. I. Directed Black 19, 38, 51, 71, 154, 168, 171, 195, C.I. I. Reactive Red 14, 32, 55, 79, 249, C.I. I. Reactive Black 3, 4, 35
Is mentioned.

  The said dye may be used individually by 1 type, and may use 2 or more types together.

Since the ink of this embodiment is the above-described light ink, the content of the coloring material is in the range of 1 to 3% by mass, and 1 to 2% by mass with respect to the total mass (100% by mass) of the ink. The range of is preferable.

[Slightly water-soluble alkanediol]
The ink of the present embodiment contains a hardly water-soluble alkanediol.

As the poorly water-soluble alkanediol, an alkanediol having 7 or more carbon atoms is preferable, and an alkanediol having 7 to 10 carbon atoms is more preferable. Of the alkanediols having 7 to 10 carbon atoms, 1,2-alkanediols that are poorly water-soluble are more preferable. In this case, since the surface tension of the ink can be reduced, the occurrence of beading can be more effectively suppressed. Examples of the poorly water-soluble 1,2-alkanediol include, but are not limited to, for example, 1,2-heptanediol, 1,2-octanediol, 5-methyl-1,2-hexanediol, 4- Methyl-1,2-hexanediol and 4,4-dimethyl-1,2-
Pentanediol is mentioned. Among these, 1,2-octanediol is particularly preferable because generation of beading can be more effectively suppressed.

The content of the slightly water-soluble alkanediol is 1 with respect to the total mass (100% by mass) of the ink.
. 0-5.0 mass% is preferable, 1.5-4.0 mass% is more preferable, 2.0-3.5
More preferred is mass%. When the amount of the slightly water-soluble alkanediol is within the above range, the occurrence of ink bleeding and beading can be suppressed, and a high-quality image can be realized. In addition to this, the initial viscosity of the ink does not become too high, and separation of the oil layer can be effectively prevented in a normal ink storage state, and the ink storage stability and clogging recovery property are good.

[Water-soluble alkanediol]
The ink of this embodiment may contain a water-soluble alkanediol. This is advantageous in that the occurrence of bleeding of a substance other than the solid content contained in the ink, that is, the aqueous solution containing the solvent can be further suppressed.

The water-soluble alkanediol contained in the ink of the present embodiment is a both-end or one-end alkanediol. The water-soluble alkanediol is preferably an alkanediol having 3 or more carbon atoms, more preferably an alkanediol having 3 to 6 carbon atoms. The water-soluble alkanediol contained in the ink of this embodiment is preferably 1,2-hexanediol, 1,6-
Examples include water-soluble hexanediol such as hexanediol, 2-methyl-1,3-propanediol, and 3-methyl-1,5-pentanediol. Among them, 1,2-hexanediol or 3-methyl-1 , 5-pentanediol is preferred. Further, 1,6-hexanediol may be used from the viewpoint of excellent discharge stability at a high frequency. Here, the both-end alkanediol means an alkanediol having a hydroxyl group at both ends of the alkyl chain main chain, and the one-end alkanediol means an alkane having a hydroxyl group at one end of the main chain of the alkyl chain. Means diol. Thus, for example, 1,6-hexanediol and 3-
Methyl-1,5-pentanediol is an alkanediol at both ends, and 1,2-hexanediol is an alkanediol at one end.

Furthermore, the content ratio (in terms of mass) of the slightly water-soluble alkanediol and the water-soluble alkanediol is preferably in the range of 5: 1 to 1: 2. By being in this range, the occurrence of beading when the landing time interval is short can be suppressed.

〔resin〕
The ink of this embodiment contains a resin.

The above resin is not limited to the following, but is modified polyolefin emulsion such as oxidized high density polyethylene wax emulsion, urethane resin, sulfonic acid ester resin,
Preferred examples include polyolefin resins, fluorene resins, and styrene-acrylic acid resins. These resins are adsorbed on the pigment and have good dispersibility. Among these, since high TI can be expressed and initial viscosity can be reduced, at least one of polyolefin resin and urethane resin is more preferable.
In addition, said resin may be used individually by 1 type, and may be used in combination of 2 or more type.

Specific examples of the hydrophobic monomer in the resin include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate,
n-propyl methacrylate, iso-propyl acrylate, iso-propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, sec-butyl acrylate, sec-butyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, n-hexyl acrylate, n-hexyl methacrylate, n-octyl acrylate, n-octyl methacrylate, iso-octyl acrylate, i
so-octyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, decyl acrylate, decyl methacrylate, lauryl acrylate,
Lauryl methacrylate, stearyl acrylate, stearyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-dimethylaminoethyl acrylate, 2-dimethylaminoethyl methacrylate, 2-diethylamino Ethyl acrylate, 2-diethylaminoethyl methacrylate, glycidyl acrylate, glycidyl methacrylate, allyl acrylate, allyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, phenyl acrylate, phenyl methacrylate, nonyl phenyl acrylate, nonyl phenyl methacrylate, benzyl acrylate, benzyl methacrylate Dicyclopentenyl acrylate, dicyclopentenyl methacrylate, bornyl acrylate, bornyl methacrylate, 1,3-butanediol diacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol diacrylate, 1, 4-butanediol dimethacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, polyethylene Glycol diacrylate, polyethylene glycol dimethacrylate, neopen Diglycol diacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, dipropylene glycol diacrylate, dipropylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, glycerol acrylate, Examples thereof include glycerol methacrylate, styrene, methyl styrene, vinyl toluene, and hydroxyethylated orthophenylphenol acrylate.
In addition, these may be used individually by 1 type and may be used in mixture of 2 or more types.

Specific examples of the hydrophilic monomer in the resin include acrylic acid, methacrylic acid, maleic acid, and itaconic acid.
In addition, these may be used individually by 1 type and may be used in mixture of 2 or more types.

  Hereinafter, resins that can be suitably used in the present embodiment will be described in detail.

(Modified polyolefin emulsion)
When the ink of the present embodiment contains the modified polyolefin emulsion, the transfer to the back surface can be suppressed when the recorded materials are superposed, and the recording surface has good abrasion resistance. In particular, the modified polyolefin emulsion has an action of softening the ink coating film, and when pressure is applied to the recording surface, the ink coating film itself is crushed to increase the binding force of components in the ink. It is considered that the rubbing property is improved. Preferred modified polyolefin emulsions are modified polyethylene emulsions and modified polypropylene emulsions. More preferable examples include oxidized polyethylene emulsion, oxidized polypropylene emulsion, (anhydrous) maleic acid-modified polyethylene emulsion, and (anhydrous) maleic acid-modified polypropylene emulsion.

The modified polyolefin emulsion is preferably a modified polyolefin having a weight average molecular weight (Mw) of 1,000 to 50,000 from the viewpoint of suppressing transfer. Moreover, as a modification method of polyolefin, it is possible to use a conventional method, for example,
A carboxylic acid-modified polyolefin can be obtained by modifying the polyolefin with an unsaturated carboxylic acid or an anhydride thereof and then dispersing the polyolefin in water in the presence of a basic compound and an emulsifier. The unsaturated carboxylic acid is preferably at least one of maleic acid and maleic anhydride.

Examples of the modified polypropylene emulsion include those obtained by modifying low molecular weight polypropylene by a heat reaction or a known method using an organic peroxide. For example,
In an inert gas atmosphere, heat-dissolve low molecular weight polypropylene in the presence of an aromatic solvent or chlorine solvent, or in the presence of a peroxide radical generating catalyst, and graft an unsaturated carboxylic acid or anhydride thereof. Obtained by denaturation.

A commercially available modified polyolefin emulsion can also be used, and is not limited to the following. For example, AQUACER 515 (oxidized high-density polyethylene wax emulsion, particle size 100), which is obtained by changing the low molecular weight polypropylene to low molecular polyethylene.
-200 nm, melting point 130 ° C., solid content 30%), AQUACER 507 (oxidized high-density polyethylene wax emulsion), AQUACER 526 (modified ethylene vinyl acetate wax emulsion), AQUACER 593 (modified polypropylene wax emulsion) (trade name, manufactured by BYK), High wax 2203A (maleic anhydride-modified polyethylene wax, trade name manufactured by Mitsui Chemicals) and Hitech E2213 (oxidized polyethylene wax emulsion, solid content 30%, trade name manufactured by Toho Chemical Co., Ltd.) can be suitably used.

(Sulfonic acid ester resin)
When the ink of this embodiment contains a sulfonic acid ester resin, it is possible to effectively suppress the glossy spots when the recording surface is rubbed.

The sulfonic acid ester resin is preferably obtained by emulsion polymerization of an ethylenically unsaturated monomer in the presence of a reactive emulsifier composed of a hydrophilic group, a hydrophobic group, and a radical reactive group.

By containing such a resin, it is possible to obtain a recorded image having excellent gloss, light resistance, and gas resistance while having glossiness equivalent to that of a silver salt photograph. The reason for this is not clear, but is considered as follows. However, it is only an assumption and is not limited to this. In other words, by emulsion polymerization of ethylenically unsaturated monomers in the presence of reactive emulsifiers,
The amount of free emulsifier remaining in the resin solution can be reduced as compared with the case of using a free emulsifier that develops excessive surface activity when the ink is dried. Therefore, the amount of free emulsifier in the water-based ink is reduced. Further, since the reactive emulsifier has a hydrophilic group, the released reactive emulsifier and the dispersion resin are well compatible in the ink. Further, the molecular weight can be lowered by adding a chain transfer agent at the time of blending various monomers and then contacting with a polymerization initiator. For the above reasons, it is considered that a recorded image having excellent gloss, light resistance, and gas resistance can be obtained while having glossiness equivalent to that of a silver salt photograph.

Here, the “reactive emulsifier” means an emulsifier having an emulsifying ability to the extent that emulsion polymerization is possible and capable of radical polymerization.

The reactive emulsifier is a compound composed of a hydrophilic group, a hydrophobic group, and a radical reactive group. Examples of the hydrophilic group include a sulfate group, a carboxylic acid group, and a polyoxyethylene group. Among these hydrophilic groups, at least one of a sulfate ester group and a polyoxyethylene group is preferable, and one having both a sulfate ester group and a polyoxyethylene group is more preferable.

As a hydrophobic group which comprises a reactive emulsifier, a C5-C20 aliphatic alkyl group and an aromatic group are preferable, for example, C8-C15 aliphatic alkyl group is more preferable among these.

Examples of the radical reactive group constituting the reactive emulsifier include ethylenically unsaturated groups such as an acrylic group, a methacryl group, an allyloxy group, a methallyloxy group, and a propenyl group. Among these, At least one of an allyloxy group and a propenyl group is preferable.

As a reactive emulsifier whose hydrophilic group is an anionic functional group, specifically, Latemul S-1
80A (manufactured by Kao Corporation), Eleminor JS-2 (manufactured by Sanyo Chemical Co., Ltd.), Aqualon KH-10,
Aqualon HS-10, Aqualon BC-10 (Daiichi Kogyo Seiyaku Co., Ltd.), Adekaria Soap SE-10N (Asahi Denka Kogyo Co., Ltd.) and the like can be suitably used. Moreover, the reactive emulsifier whose hydrophilic group is a cationic functional group can also be used conveniently. Furthermore, as a reactive emulsifier whose hydrophilic group is a nonionic functional group, Aqualon RS-20 (Daiichi Kogyo Seiyaku Co., Ltd.), Adekaria Soap ER-20 (Asahi Denka Kogyo Co., Ltd.), etc. are preferably used. it can. Said reactive emulsifier may be used individually by 1 type, and may be used in combination of 2 or more type.

The content of the reactive emulsifier contained in the ink is preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the ethylenically unsaturated monomer, although it depends on the particle size of the resin emulsion described later. More preferably, it is 5-3 mass parts. By including the reactive emulsifier within this range, the emulsion polymerization reaction can be carried out stably, and the resin can be sufficiently emulsified. Further, when added to the ink, the problem of foaming does not occur.

In the ink of this embodiment, in addition to the reactive emulsifier, an anionic emulsifier, a nonionic emulsifier, a cationic emulsifier, a zwitterionic emulsifier, or a non-reactive emulsifier such as a water-soluble resin is added. Also good. By using a non-reactive emulsifier in combination, the storage stability of the emulsion can be improved.

Examples of the anionic emulsifier include alkali metal salts of higher alcohol sulfates, alkali metal salts of alkylbenzene sulfonic acids, alkali metal salts of succinic acid dialkyl ester sulfonic acids, alkali metal salts of alkyl diphenyl ether disulfonic acids, and polyoxyethylene alkyl ethers. And sulfuric acid ester salts of polyoxyethylene alkyl phenyl ethers, phosphoric acid ester salts of polyoxyethylene alkyl phenyl ethers, and phosphoric acid ester salts of polyoxyethylene alkyl phenyl ethers.

Examples of the nonionic emulsifier include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, and alkyl ether having a sugar chain as a hydrophilic group.

Examples of the cationic emulsifier include alkyl pyridinyl chloride and alkyl ammonium chloride.

  Examples of zwitterionic emulsifiers include lauryl betaine.

Examples of water-soluble resins include alkali neutralized products of polycarboxylic acid polymers obtained by copolymerizing aromatic monomers and monomers containing carboxyl groups, polyvinyl alcohol, and enzymatically degraded starch. It is done.

These non-reactive emulsifiers may be used alone or in combination of two or more.

The content of the non-reactive emulsifier contained in the ink is preferably 5 parts by mass or less with respect to 100 parts by mass of the ethylenically unsaturated monomer. However, in the case where a water-soluble resin is used as the non-reactive emulsifier, the content of the non-reactive emulsifier is 100% ethylenically unsaturated monomer.
It is preferable that it is 50 mass parts or less with respect to a mass part.

The resin contained in the ink of the present embodiment is obtained by emulsion polymerization of an ethylenically unsaturated monomer in the presence of the reactive emulsifier. There is no restriction | limiting in particular as an ethylenically unsaturated monomer to be used, 1,3-butadiene, 1,2-butadiene, 1,2-pentadiene, 1,3-pentadiene, 2,3-pentadiene, isoprene, 1,2- Hexadiene,
1,3-hexadiene, 1,4-hexanediene, 1,5-hexazine, 2,3-hexadiene, 2,4-hexadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-
1,3-butadiene, 1,2-heptadiene, 13, -heptadiene, 1,4-heptadiene, 1,5-heptadiene, 1,6-heptadiene, 2,3-heptadiene, 2,5-
Diene monomers such as heptadiene, 3,4-heptadiene, 3,5-heptadiene, cyclopentadiene, dicyclopentadiene, ethylidene norbornene, styrene, α-
Aromatic monomers such as methyl styrene, o-methyl styrene, p-methyl styrene, m-methyl styrene, vinyl naphthalene, divinyl styrene, methyl (meth) acrylate, (
(Meth) ethyl acrylate, (meth) acrylate n-propyl, (meth) acrylate i-propyl, (meth) acrylate n-butyl, (meth) acrylate n-amyl, (meth) acrylate i-amyl Hexyl (meth) acrylate, 2-hexyl hexyl (meth) acrylate, octyl (meth) acrylate, i-nonyl (meth) acrylate, decyl (meth) acrylate, hydroxymethyl (meth) acrylate, ( (Meth) acrylic acid alkyl esters such as hydroxylethyl methacrylate, itaconic acid, fumaric acid, (meth) acrylic acid, maleic acid, crotonic acid and other unsaturated carboxylic acids, (meth) acrylamide, N-methylolacrylamide, etc. Of ethylenically unsaturated carboxylic acid alkylamides, vinyl acetate, vinyl propionate, etc. Rubonic acid vinyl ester, ethylenically unsaturated dicarboxylic acid anhydride, monoalkylester, monoamide, aminoethyl acrylate, dimethylaminoethyl acrylate, aminoalkyl ester of ethylenically unsaturated carboxylic acid such as butylaminoethyl acrylate, amino Ethylenically unsaturated carboxylic acid aminoalkylamides such as ethyl acrylamide, dimethylaminomethyl methacrylamide, methylaminopropyl methacrylamino, vinyl cyanide compounds such as (meth) acrylonitrile, α-chloroacrylonitrile, glycidyl (meth) acrylate, etc. Unsaturated aliphatic glycidyl ester etc. can be used and these monomers may be used individually by 1 type, or may be used in combination of 2 or more type.

Among the above monomers, (such as 1,3-butadiene, isoprene, styrene, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate) A (meth) acrylic acid alkyl ester that is a (meth) acrylic monomer can be suitably used, and a (meth) acrylic acid alkyl ester is particularly preferred.

In addition, the ethylenically unsaturated monomer includes an alkoxysilane group, an epoxy group, a hydroxyl group,
Alternatively, it may have a functional group such as a polyethylene oxide group. By having such a functional group, the compatibility between the resin and each of the other components in the ink can be improved. Among these, a monomer having an alkoxysilane group is particularly preferably used.

Examples of the alkoxysilane group-containing monomer include γ-methacryloxypropyltriethoxysilane, γ-acryloxypropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane, vinyltriethoxysilane, vinyl A trimethoxysilane is mentioned. Moreover, glycidyl (meth) acrylate is mentioned as an epoxy group containing monomer. As the hydroxyl group-containing monomer, 2-
Examples thereof include hydroxyethyl methacrylate. Examples of the polyethylene oxide group-containing monomer include polyethylene glycol monomethacrylate and the like that can be obtained as BLEMMER PE200 (manufactured by NOF Corporation).

The functional group-containing monomer is preferably contained in the monomer in an amount of 10% by weight or less, more preferably 5% by weight or less.

Resin is obtained by carrying out emulsion polymerization of the ethylenically unsaturated monomer demonstrated above in presence of the reactive emulsifier which consists of a hydrophilic group, a hydrophobic group, and a radical reactive group.

In the emulsion polymerization, the reactive emulsifier is 0.5% with respect to 100 parts by mass of the ethylenically unsaturated monomer.
-5 parts by mass, water is mixed at a ratio of 100-5,000 parts by mass, an ethylenically unsaturated monomer and a radical polymerization initiator are added to the mixture, and the polymerization temperature is 0.1 to 0.1 at a polymerization temperature of 5-100 ° C. 10
This is done by reacting for a period of time. The polymerization temperature is preferably 30 to 90 ° C., and the polymerization time is 2
˜5 hours is preferred.

The radical polymerization agent includes an oxidizing agent composed of organic hydroperoxides such as cumene hydroperoxide, diisopropylbenzene peroxide and diisopropylbenzene hydroperoxide, and a reducing agent in a mixed formulation of a sugar-containing pyrophosphate formulation and a sulfoxylate formulation. Redox initiators, potassium persulfate, persulfates such as ammonium persulfate, azobisisobutyronitrile, dimethyl-2,2′-azobisisobutyrate, 2-carbamoylazaisobutyro An azo initiator such as nitrile and organic peroxides such as benzoyl peroxide and lauroyl peroxide can be preferably used. Among these, an organic peroxide is preferable.

In the emulsion polymerization, other emulsifiers and organic solvents may be used as necessary. Moreover, the addition method in particular of an ethylenically unsaturated monomer is not restrict | limited, It can carry out by arbitrary methods, such as a batch addition method, a continuous addition method, or a division addition method.

In this embodiment, it is preferable to carry out emulsion polymerization of an ethylenically unsaturated monomer in the presence of a chain transfer agent in addition to a reactive emulsifier. By using the chain transfer agent in combination, a recorded image having further excellent gloss, fixability, light resistance and gas resistance can be obtained. The reason for this is not clear, but it is considered that the chain transfer agent is bonded to the polymer terminal of the resin during emulsion polymerization. However,
This is only an assumption, and the present embodiment is not limited to this.

Examples of the chain transfer agent include octyl mercaptan, n-dodecyl mercaptan, t
-Mercaptans such as dodecyl mercaptan, n-hexadecyl mercaptan, n-tetradecyl mercaptan, t-tetradecyl mercaptan; xanthogen disulfides such as dimethylxanthogen disulfide, diethylxanthogen disulfide, diisopropylxanthogen disulfide, tetramethylthiuram disulfide, tetraethylthiuram Disulfides, thiuram disulfides such as tetrabutylthiuram disulfide, halogenated hydrocarbons such as carbon tetrachloride, ethylene bromide, pentaphenylethane, 1
, 1-diphenylethylene, hydrocarbons such as α-methylstyrene dimer, and acrolein, methacrolein, allyl alcohol, 2-ethylhexyl thioglycolate,
Examples include terpinolene, α-terpinene, γ-terpinene, and dipentene. Among these, mercaptans, xanthogen disulfides, thiuram disulfides,
It is preferable to use carbon tetrachloride, 1,1-diphenylethylene, α-methylstyrene dimer, 2-ethylhexyl thioglycolate. The said chain transfer agent may be used individually by 1 type, and may be used in combination of 2 or more type.

The addition amount of the chain transfer agent is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 7 parts by mass, and still more preferably 100 parts by mass in total of the ethylenically unsaturated monomer and the reactive emulsifier. Is 0.2-5 parts by mass, and more preferably 0.3-3 parts by mass. By making the addition amount of the chain transfer agent in the above range, the gloss of the recorded matter becomes better and the rubbing resistance is sufficient.

The resin thus obtained is present in the form of an emulsion in the polymerization solution. In the ink of this embodiment, the resin is preferably present in the form of an emulsion in the ink (hereinafter also referred to as a resin emulsion). The average particle size of the resin emulsion is 10 to
100 nm is preferable, and 30 to 60 nm is more preferable. When the average particle diameter exceeds 100 nm, the storage stability becomes insufficient, and it becomes difficult to form a thin and uniform film by electrodeposition. Further, compatibility with each component of the ink is lowered. On the other hand, when the average particle size is less than 10 nm, the polymerization stability is significantly reduced. The said average particle diameter can be adjusted with the addition amount of a chain transfer agent and an emulsifier, as well as the kind and blending ratio of monomers.

The sulfonic acid ester resin thus obtained preferably has a weight average molecular weight of 10,000 to 100,000, more preferably 30,000 to 70,000. By using a resin having a relatively low molecular weight in this way, the emulsion can be easily fused when the ink is dried. The weight average molecular weight of the resin can be adjusted by the type and amount of the polymerization initiator and the use of a chain transfer agent.

(Polyolefin resin)
When the ink of this embodiment contains a polyolefin resin, it is possible to prevent the recording surface from being scratched and to further improve the ink fixability.

The polyolefin resin preferably has a particle diameter larger than the dry film thickness of the film formed by depositing ink onto the recording surface. By adhering to the recording surface as particles protruding from the ink coating film, the polyolefin resin particles are crushed by themselves when pressure is applied to the recording surface, and the slip of the outermost surface of the ink coating film can be improved. it is conceivable that.

The average particle diameter of the polyolefin resin is preferably 76 nm or more, more preferably 150 nm.
nm or more, more preferably 200 nm or more, still more preferably 200 nm to 1 μm
It is.

The polyolefin resin has a melting point or ring-and-ball softening point (JIS K2207) of preferably 110 ° C. or higher, and preferably 110 to 150 ° C. in that the polyolefin resin tends to remain as particles on a film fixed to the recording surface of the ink. It is more preferable.

The polyolefin resin has a penetration hardness (JIS K2207) of preferably 1 or more, more preferably 2 to 5.

The polyolefin resin is not particularly limited as long as the state of particles having a predetermined particle diameter can be maintained in a film (a coating film such as a recorded image) formed when ink is deposited on a recording surface. For example, a wax produced from an olefin such as ethylene, propylene, butylene or a derivative thereof and a copolymer thereof, specifically, a polyethylene wax, a polypropylene wax, a polybutylene wax or the like may be used alone or in combination.

In addition, as the polyolefin resin, it is also possible to use a commercially available one. As a specific example thereof, “Chemical Pearl W4005” (polyethylene wax, particle diameter 20
Chemipearl series such as 0 nm to 800 nm, ring and ball method softening point 110 ° C., penetration method hardness 3, solid content 40%, manufactured by Mitsui Chemicals, Inc. can be suitably used. JP 2003-20
A polyolefin resin described in Japanese Patent No. 1436 can also be suitably used.

(Copolymer resin)
Since the copolymer resin of the hydrophobic monomer and the hydrophilic monomer achieves both color image glossiness, bronzing prevention, and ink storage stability, and can form a color image with even higher glossiness, styrene. -(Meth) acrylic acid resin, styrene-methylstyrene-
(Meth) acrylic acid resin, or styrene-maleic acid resin, (meth) acrylic acid- (meth) acrylic ester resin, or styrene- (meth) acrylic acid- (meth) acrylic ester resin, and hydroxyethylated ortho Phenylphenol acrylate ester- (
It is preferably at least one of a (meth) acrylic resin.

The copolymer resin is more preferably a resin (styrene-acrylic acid resin) containing a polymer obtained by reacting styrene with acrylic acid or an ester of acrylic acid. The copolymer resin may be an acrylic acid-based water-soluble resin. Moreover, salts such as sodium, potassium, ammonium, triethanolamine, triisopropanolamine, triethylamine, and diethanolamine may be used.

The acid value of the copolymer resin is preferably 5 because the color image glossiness, bronzing prevention, and ink storage stability are compatible, and a color image with further excellent glossiness can be formed.
It is 0-320, More preferably, it is 100-250.

The weight average molecular weight (Mw) of the copolymer resin is preferably 2 from the viewpoint of achieving both color image glossiness, bronzing prevention, and ink storage stability while being able to form a color image with even higher glossiness. 3,000 to 30,000, more preferably 2,000 to 20,000.

The glass transition temperature (Tg: measured in accordance with JIS K6900) of the above copolymer resin is compatible with color image glossiness, bronzing prevention and ink storage stability, and can form a color image with even higher glossiness. , Preferably 30 ° C. or higher, more preferably 5
0 to 130 ° C.

The above copolymer resin may be adsorbed to the pigment or separated from the pigment in the pigment dispersion, and achieves both glossiness of color images, prevention of bronzing, and storage stability of ink, and further glossiness. In order to form a color image having excellent properties, the copolymer resin preferably has a maximum particle size of 0.3 μm or less, and an average particle size of 0.2 μm or less (more preferably 0
. 1 μm or less).

The content of the copolymer resin is compatible with the glossiness of the color image, prevention of bronzing, and storage stability of the ink, and can form a color image with further excellent glossiness.
Preferably it is 20-50 mass parts with respect to 00 mass parts, More preferably, it is 20-40 mass parts.

(Urethane resin)
The ink according to this embodiment can form a color image having both glossiness of color image, prevention of bronzing, and storage stability of ink and excellent glossiness by using a urethane resin as a fixing pigment dispersant. . Urethane resin is a resin containing a polymer obtained by reacting a diisocyanate compound and a diol compound, but in this embodiment,
A resin having at least one of a urethane bond and an amide bond and an acidic group is preferable.

Examples of the diisocyanate compound include hexamethylene diisocyanate, 2,2
Aromatic diisocyanate compounds such as 1,4-trimethylhexamethylene diisocyanate, aromatic diisocyanate compounds such as toluylene diisocyanate and phenylmethane diisocyanate, and modified products thereof.

Examples of the diol compound include polyethers such as polyethylene glycol and polypropylene glycol, polyesters such as polyethylene abido and polybutylene abates, and polycarbonates.

The acid value of the urethane resin is preferably 10 to 300 from the viewpoint of achieving a color image having a glossy color image, prevention of bronze, and storage stability of the ink while being able to form a color image having further excellent glossiness. More preferably, it is 20-100. In addition, the acid value in this specification is the mg amount of KOH required to neutralize 1 g of resin.

The weight-average molecular weight (Mw) before crosslinking of the urethane resin is preferably from the viewpoint of achieving a color image having both glossiness of a color image, prevention of bronzing, and storage stability of the ink and excellent glossiness. Is 100 to 200,000, more preferably 1000 to 50,000. Mw is measured by GPC (gel permeation chromatography), for example.

The glass transition temperature (Tg: measured in accordance with JIS K6900) of the urethane resin is from the viewpoint of achieving a color image having both glossiness of color image, prevention of bronzing, and storage stability of ink and excellent glossiness. The temperature is preferably -50 to 200 ° C, more preferably -50 to 100 ° C.

  The urethane resin preferably has a carboxyl group.

The content of the urethane resin is based on 100 parts by mass of the pigment from the viewpoint of achieving a color image having both glossiness of a color image, prevention of bronzing, and storage stability of the ink and excellent glossiness. , Preferably 20-50 parts by mass, more preferably 20-
40 parts by mass.

(Fluorene resin)
By using a fluorene resin as the fixing pigment dispersant, the ink of the present embodiment is excellent in reducing the initial viscosity of the ink, storage stability at high temperatures, and fixing properties to printing paper.

The fluorene resin is not limited as long as it has a fluorene skeleton, and can be obtained, for example, by copolymerizing the following monomer units.

5-Isocyanate-1- (isocyanatemethyl) -1,3,3-trimethylcyclohexane (CAS No. 4098-71-9)

2,2 ′-[9H-Fluorene-9-ylidenebis (4,1-phenyleneoxy)] bisethanol (CAS No. 117344-32-8)

3-hydroxy-2- (hydroxymethyl) -2-methylpropionic acid (CAS No.
. 4767-03-7)

  N, N-diethyl-ethanamine (CAS No. 121-44-8)

The fluorene resin is not particularly limited as long as the resin has a fluorene skeleton, and the monomer composition ratio is not limited, but preferably 5-isocyanate-1- (isocyanatemethyl) -1,3,3-trimethylcyclohexane (CAS). No. 4098-71-9)
Is 35 to 45 mass%, 2,2 ′-[9H-fluorene-9-ylidenebis (4,1-phenyleneoxy)] bisethanol (CAS No. 117344-32-8) is 40 to 6
0% by mass, 3-hydroxy-2- (hydroxymethyl) -2-methylpropionic acid (CA
S No. 4767-03-7) is 5 to 15% by mass, N, N-diethyl-ethanamine (
CAS No. 121-44-8) is 5 to 15% by mass.

The number average molecular weight (Mn) before crosslinking of the fluorene resin reduces the initial viscosity of the ink,
And in order to make the storage stability of an ink compatible, Preferably it is 2000-5000, More preferably, it is 3,000-4,000. Mn is measured by, for example, GPC (gel permeation chromatography).

The fluorene resin may be adsorbed to the pigment in the pigment dispersion or may be free, and it achieves color image gloss, bronzing prevention, and ink storage stability, and is even more glossy. From the viewpoint of forming an excellent color image, the maximum particle size of the resin is preferably 0.3 μm or less, and the average particle size is 0.2 μm or less (more preferably 0.1 μm or less). preferable.

The content of the fluorene resin is preferable with respect to 100 parts by mass of the pigment because it can form a color image having both excellent fixability of the color image, prevention of bronzing, and storage stability of the ink and excellent fixability. Is 20-50 parts by weight, more preferably 20-40
Part by mass.

The mass ratio (the former / the latter) of the resin and the fixing pigment dispersant is preferably 1/2 to 2/1. However, both the glossiness of the color image, the prevention of bronzing, and the storage stability of the ink are achieved. Since a color image excellent in glossiness can be formed, it is more preferably 1 / 1.5 to 1.5 / 1.

The mass ratio (the former / the latter) of the solid content of the pigment and the solid content of the resin and the fixing pigment dispersant is compatible with the glossiness of the color image, the prevention of bronzing, and the storage stability of the ink. Since it is possible to form a color image with further excellent glossiness, 100/40 to 100/100
It is preferable that

[Surfactant]
In the ink of this embodiment, a surfactant may be used as a dispersant. Such surfactants include fatty acid salts, higher alkyl dicarboxylates, higher alcohol sulfates, higher alkyl sulfonates, condensates of higher fatty acids and amino acids, sulfosuccinate esters, naphthenates, liquid fats. Anionic surfactants such as oil sulfate esters and alkyl allyl sulfonates, and cationic surfactants such as fatty acid amine salts, quaternary ammonium salts, sulfonium salts, and phosphoniums, and polyoxyethylene alkyl ethers, Nonionic surfactants such as polyoxyethylene alkyl esters, sorbitan alkyl esters, and polyoxyethylene sorbitan alkyl esters can be mentioned. It goes without saying that the above-described surfactant is also added to the ink so as to function as a surfactant.

The ink of this embodiment can be produced by dispersing and mixing the above components by an appropriate method. Preferably, first, a pigment, a polymer dispersant and water are mixed with a suitable disperser (for example,
Ball mill, sand mill, attritor, roll mill, agitator mill, Henschel mixer, colloid mill, ultrasonic homogenizer, jet mill, ang mill, etc.) to prepare a uniform pigment dispersion, and then separately prepared resin (resin emulsion) ), Water, water-soluble organic solvent, sugar, pH adjuster, preservative, fungicide, etc. are added and sufficiently dissolved to prepare an ink solution. After sufficiently stirring, the target ink can be obtained by performing filtration in order to remove the coarse particle diameter and foreign matters that cause clogging. The filtration may be performed using a glass fiber filter as a filter medium. The glass fiber is preferably a resin-impregnated glass fiber from the viewpoint of the electrostatic adsorption function. Further, the pore diameter of the glass fiber filter is preferably 1 to 40 μm, more preferably 1 to 10 μm, from the viewpoint of productivity and adsorption removal of charged free resin and the like. By sufficiently removing and adsorbing the charged free resin and the like, the discharge stability can be improved. An example of the filter is Ultipore GF Plus manufactured by Nippon Pole.

[(Poly) oxyalkylene glycol]
The ink of this embodiment may contain (poly) oxyalkylene glycol.

When the ink of this embodiment contains (poly) oxyalkylene glycol, (poly)
The oxyalkylene glycol is preferably a water-miscible oligomer obtained by addition polymerization of at least one of ethylene oxide and propylene oxide. More preferably, it is at least one selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol, and more preferably triethylene glycol,
It is one or more selected from the group consisting of propylene glycol, dipropylene glycol, and tripropylene glycol. The (poly) oxyalkylene glycol is more preferably a water-miscible (poly) propylene glycol.

In this embodiment, (poly) oxyalkylene glycol is the total mass of ink (10
0 to 1% by mass), preferably 2.0 to 18.0% by mass, 6.0 to 1
8.0 mass% is more preferable. By setting the amount of the (poly) oxyalkylene glycol within the above range, the slightly water-soluble alkanediol can be kept in a mixed state without being separated in the ink droplet drying step. In addition to this, the initial viscosity of the ink does not become excessively high, and separation of the oil layer can be effectively prevented under normal ink storage conditions. Also excellent.

In addition, since (poly) oxyalkylene glycol is difficult to dry even when left at high temperature and low humidity, the nozzle clogging recovery performance in an open environment with a relative humidity of 15% RH at 50 ° C. can be improved. Have.

Further, the sum of the contents of the (poly) oxyalkylene glycol and the wetting agent is preferably 12.0% by mass or more and 60.0% by mass or less based on the total mass (100% by mass) of the ink. 0 mass% or more and 54.0 mass% or less are more preferable. When the sum is within the above range, it is excellent in curling suppression in various recording media, particularly low water-absorbing recording media.

[Sugar]
This embodiment may include saccharides. Examples of the saccharide include monosaccharides, disaccharides, oligosaccharides (including trisaccharides and tetrasaccharides), polysaccharides, and derivatives thereof. Among these, glucose, mannose, fructose, ribose, xylose, arabinose, galactose, glucitol, sorbitol, maltose, cellobiose, lactose, sucrose, trehalose, maltotriose, phyllanose, raffinose and the like are preferable. Among these, raffinose is more preferable. By adding raffinose to the ink of this embodiment, the intermittent printing characteristics are improved.

The polysaccharide means a saccharide in a broad sense and includes substances widely present in nature such as alginic acid, α-cyclodextrin, cellulose and the like. Examples of derivatives of these saccharides include reducing sugars of the saccharides described above (for example, sugar alcohol (general formula: HOCH ₂ (CHOH) _n CH
₂ OH (wherein n represents an integer of 2 to 5)), oxidized sugar (such as aldonic acid and uronic acid), amino acid, and thiosaccharide. Among these, sugar alcohols are preferable, and specific examples include maltitol, sorbitol, and xylitol. These saccharides may be commercially available, for example, HS20, HS30, HS500 (
Hayashibara Shoji Co., Ltd.) and Oligo GGF (Asahi Kasei Corporation) can be preferably used.

Further, it is considered that dialkylene glycol and water-soluble alkanetriol or saccharide also have a function as a solubilizing agent for poorly water-soluble alkanediol.

(Penetration agent)
Further, the ink of the present embodiment may contain a penetrant in addition to the above components. As the penetrant, glycol ethers can be preferably used.

Specific examples of glycol ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-iso.
-Butyl ether, ethylene glycol mono-tert-butyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol mono-iso-propyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol Mono-tert-butyl ether, triethylene glycol mono-n-butyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, propylene glycol mono-n- Butyl ether Propylene glycol monobutyl -tert- butyl ether,
Dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol-i
Examples include so-propyl ether, dipropylene glycol mono-n-butyl ether, dipropylene glycol mono-tert-butyl ether, 1-methyl-1-methoxybutanol, and the like, which can be used as a mixture of one or more of these.

Among the glycol ethers, alkyl ethers of polyhydric alcohols are preferable,
Especially ethylene glycol monoethyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, triethylene glycol Monomethyl ether, triethylene glycol monoethyl ether or triethylene glycol mono-n-butyl ether is preferred.

More preferred are triethylene glycol monomethyl ether and triethylene glycol mono-n-butyl ether.

The amount of the penetrant added may be appropriately determined, but is preferably about 0.1 to 30% by mass.
About -20 mass% is more preferable.

[Surfactant]
The ink of this embodiment may contain a surfactant. By using a surfactant for a recording medium having a fiber layer on the surface, such as plain paper,
Since bleeding can be adjusted, an image expressing excellent fine lines can be realized. In particular, even when using a recording medium such as a printing paper in which a coating layer for receiving oil-based ink is provided in the receiving layer on the surface, bleeding can be prevented and the amount of ink adhered can be reduced. It is possible to prevent whitening due to reflected light of light generated with the increase.

As the surfactant used in the present embodiment, a polyorganosiloxane-based surfactant can be suitably used, and wettability (affinity) to the surface of a recording medium when a recorded image is formed.
To improve the ink permeability. When a polyorganosiloxane surfactant is used, it contains one kind of poorly water-soluble alkanediol and one kind of (poly) oxyalkylene glycol as described above. The solubility of the ink is improved and the generation of insoluble matter or the like can be suppressed, so that it is possible to realize an ink with more excellent ejection stability.

Such a surfactant may be a commercially available one, for example, BYK-347.
BYK-348 (manufactured by BYK) or the like can be used.

As the surfactant used in the present embodiment, the polyorganosiloxane surfactant is not particularly limited, but 20% by mass of glycerin, 10% by mass of 1,2-hexanediol, and the polyorganosiloxane interface. 0.1% by weight of activator and 69 of water
. In the case of an aqueous solution containing 9% by mass, the 1 Hz dynamic surface tension of the aqueous solution is 26 mN / m.
It is particularly preferred to use: The dynamic surface tension can be measured using, for example, a bubble pressure dynamic surface tension meter BP2 (manufactured by KRUS).

As the surfactant as described above, commercially available ones may be used.
D-501, Olfin PD-570 (manufactured by Nissin Chemical Industry Co., Ltd.) and the like can be used.

  Further, as the polyorganosiloxane surfactant, the following chemical formula (I):

上記化学式（Ｉ）の化合物において、Ｒ、ａ、ｍ、及びｎは以下の組み合わせをとるこ
とが好ましい。
まず、Ｒは水素原子又はメチル基であり、ａは２〜１３の整数であり、ｍは２〜７０の
整数であり、ｎは１〜８の整数であることが好ましい。
また、Ｒは水素原子又はメチル基であり、ａは２〜１３の整数であり、ｍは２〜５０の
整数であり、ｎは１〜８の整数であることがより好ましい。
また、Ｒは水素原子又はメチル基であり、ａは２〜１３の整数であり、ｍは２〜５０の
整数であり、ｎは１〜５の整数であることが好ましい。
また、Ｒは水素原子又はメチル基であり、ａは２〜１１の整数であり、ｍは２〜５０の
整数であり、ｎは１〜５の整数であることが好ましい。
また、Ｒはメチル基であり、ａは６〜１８の整数であり、ｍは０〜４であり、ｎは１又
は２であることが好ましい。
また、Ｒはメチル基であり、ａは６〜１８の整数であり、ｍは０であり、ｎは１である
ことがより好ましい。
なお、ポリオルガノシロキサン系界面活性剤は、上記の好ましい組み合わせを有する化
合物を１種単独で含んでもよく２種以上含んでもよい。以上のような特定のオルガノポリ
シロキサン系界面活性剤を使用することにより、被記録媒体として印刷本紙に印刷した場
合であっても、インクの凝集ムラがより改善される。

In the compound of the above chemical formula (I), R, a, m, and n preferably take the following combinations.
First, R is a hydrogen atom or a methyl group, a is an integer of 2 to 13, m is an integer of 2 to 70, and n is preferably an integer of 1 to 8.
R is a hydrogen atom or a methyl group, a is an integer of 2 to 13, m is an integer of 2 to 50, and n is more preferably an integer of 1 to 8.
R is a hydrogen atom or a methyl group, a is an integer of 2 to 13, m is an integer of 2 to 50, and n is preferably an integer of 1 to 5.
R is a hydrogen atom or a methyl group, a is an integer of 2 to 11, m is an integer of 2 to 50, and n is preferably an integer of 1 to 5.
R is a methyl group, a is an integer of 6 to 18, m is 0 to 4, and n is preferably 1 or 2.
R is a methyl group, a is an integer of 6 to 18, m is 0, and n is more preferably 1.
In addition, the polyorganosiloxane-based surfactant may contain one kind of compounds having the above preferred combination, or may contain two or more kinds. By using the specific organopolysiloxane-based surfactant as described above, the ink aggregation unevenness is further improved even when printing is performed on printing paper as a recording medium.

In the compound of the above chemical formula (I), suppression of occurrence of beading can be further improved by using a compound in which R is a methyl group. In addition, in the compound represented by the chemical formula (I), ink bleeding can be further improved by using a compound in which R is a hydrogen atom.

In the compound of the above formula (I), by appropriately adjusting the blending ratio of the compound in which R is a methyl group and the compound in which R is a hydrogen atom, a high-quality image in which the occurrence of bleeding and beading is further suppressed is obtained. It can be realized and is effective as a regulator when the fluidity varies depending on the pigment type and the amount of resin.

The surfactant is preferably 0.01 to in the ink (100% by mass) of the present embodiment.
1.0 mass%, More preferably, 0.05 to 0.50 mass% is contained. In particular, when using the above-mentioned surfactant in which R is a hydrogen group, reducing the content suppresses the occurrence of beading compared to the case of using the above-described surfactant in which R is a methyl group. Is preferable. R
By containing 0.01 to 0.1% by mass of a surfactant having a hydrogen group, water repellency is exhibited and bleeding can be adjusted.

Other inks such as acetylene glycol surfactants, anionic surfactants, nonionic surfactants, and amphoteric surfactants may be further added to the ink of this embodiment.

Of these, acetylene glycol surfactants include, for example, 2, 4, 7, 9
-Tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3
, 6-diol, or 3,5-dimethyl-1-hexyne-3ol, 2,4-dimethyl-
5-hexyn-3-ol etc. are mentioned. Also, commercially available acetylene glycol surfactants can be used. For example, Olfin E1010, STG, Y (trade name,
Nissin Chemical Co., Ltd.), Surfinol 61, 104, 82, 465, 485, or TG (
Trade name, manufactured by Air Products and Chemicals Inc.).

[Water, other ingredients]
The ink of this embodiment may contain water. It is preferable to use pure water or ultrapure water such as ion exchange water, ultrafiltration water, reverse osmosis water, or distilled water. In particular, water obtained by sterilizing these waters by ultraviolet irradiation or addition of hydrogen peroxide is preferable because generation of mold and bacteria is prevented over a long period of time.

The ink of this embodiment further includes a nozzle clogging preventive agent such as glycerin, an antiseptic, an antioxidant, a conductivity adjusting agent, a pH adjusting agent, a viscosity adjusting agent, a surface tension adjusting agent, an oxygen absorber, and the like. be able to.

Examples of preservatives and fungicides that can be included in the ink of this embodiment include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, and 1.2. -Dibenzthiazoline-
3-on (ICI Proxel CRL, Proxel BND, Proxel GXL, Proxel XL-2, Proxel TN) and the like can be mentioned.

Further, examples of pH adjusters, dissolution aids, or antioxidants that can be included in the ink of the present embodiment include amines such as diethanolamine, triethanolamine, propanolamine, morpholine, and their modified products, potassium hydroxide. , Inorganic salts such as sodium hydroxide and lithium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide (tetramethylammonium etc.), carbonates such as potassium carbonate, sodium carbonate, lithium carbonate and other phosphates, or N- L-ascorbic acid and its salts such as ureas such as methyl-2-pyrrolidone, urea, thiourea and tetramethylurea, allophanates such as allophanate and methylallohanate, biurets such as biuret, dimethylbiuret and tetramethylbiuret To mention That.

Further, the ink of the present embodiment may contain an antioxidant and an ultraviolet absorber, and examples thereof include Tinuvin 328, 900, 1130, 384, 292, and 12 manufactured by BASF.
3, 144, 622, 770, 292, Irgacor 252, 153, Irgano
x 1010, 1076, 1035, MD1024, and an oxide of lanthanide.

[Physical properties of ink for inkjet recording]
As described above, the ink of the present embodiment can exhibit a desired effect by controlling not only the constituent components but also the physical properties.

The surface tension of the ink is 21 to 25 mN / m, and preferably 22 to 24 mN / m. If the surface tension is within the above range, ink droplets attached to the recording medium will not flow easily.
Bleeding, bleeding, and beading at the edge can be effectively suppressed.

Further, the total mass (100) before ink evaporation due to ink evaporation represented by the above formula (1).
The ink has a thixotropy index (TI) of 2 to 110, preferably 4 to 110. When the TI is within the above range, the fluidity after adhering to the recording medium can be suppressed, that is, the pseudoplastic fluid can be expressed on the recording medium. Both bleeding and beading and ink bleeding at the edge can be suppressed. In particular, when the upper limit of TI is 110 or less, it is possible to reduce the influence of an increase in the viscosity of the ink at the nozzle due to volatilization of the solvent.

The initial viscosity of the ink is preferably 3 to 10 mPa · s, and more preferably 3 to 6 mPa · s. When the initial viscosity is within the above range, the ink can be ejected from the head, so that the ink is suitable for inkjet recording applications.

As described above, according to the present embodiment, it is possible to provide an ink for inkjet recording that is excellent in clogging recovery, can suppress bleeding and beading, and can also suppress ink bleeding at the edge.

[Recording medium]
The recording medium to be recorded by the ink of the present embodiment is not particularly limited. For example, a recording medium having a receiving layer of plain paper or water-based ink, or a recording medium having low water absorption is suitable. Can be used.
Examples of the low water-absorbing recording medium include coated paper, and recording paper (printing paper) such as finely coated paper, art paper, coated paper, matte paper, and cast paper.

Coated paper is paper whose surface is coated with a paint to enhance aesthetics and smoothness. The paint can be prepared by mixing pigments such as talc, pyrophyllite, clay (kaolin), titanium oxide, magnesium carbonate, and calcium carbonate and an adhesive such as starch and polyvinyl alcohol. The paint is applied using a machine called a coater in the paper manufacturing process. The coater
There are two types: an on-machine type in which papermaking and coating are performed in one step by being directly connected to a paper machine, and an off-machine type in which the papermaking is performed separately. It is mainly used for recording and is classified as coated paper for printing in the “Production Dynamic Statistics Classification” of the Ministry of Economy, Trade and Industry.

The finely coated paper refers to a recording paper having a coating amount of 12 g / m ² or less. Art paper refers to recording paper obtained by applying a coating of about 40 g / m ^{2 to} high-grade recording paper (high-quality paper, paper with a chemical pulp usage rate of 100%). The coated paper, refers to a recording sheet which was coated with a 20g / m ² ~40g / m ² about the paint. The cast paper refers to a recording paper obtained by finishing art paper or coated paper by applying pressure to the surface with a machine called a cast drum so that the gloss and the recording effect are further enhanced.

Synthetic paper or printing paper (OKT +, manufactured by Oji Paper Co., Ltd.) is preferably used as the low water-absorbing recording medium, but particularly for high-quality paper and laser printers used for art paper and POD (print on demand) applications. Even when printing on special paper, especially at low resolution,
High quality images with reduced bleeding and beading can be realized. Examples of the high-quality paper for POD use include Ricoh Business Coat Gloss 100 (manufactured by Ricoh). In addition, as dedicated paper for laser printers, for example, LPCCTA4 (
Seiko Epson Corporation). Examples of water-resistant paper include Kaleka (manufactured by Mitsubishi Chemical Media) and laser peach (manufactured by Nisshinbo Postal Chemical).

[Ink set for inkjet recording]
An ink set for ink jet recording according to an embodiment of the present invention includes the ink for ink jet recording (light ink) of the above embodiment and the ink for ink jet recording (dark ink) containing a color material having a predetermined density. The content of the coloring material is the total mass of the ink (100% by mass).
) To 5 to 7% by mass, preferably 5 to 6% by mass.

As described above, an ink set including a predetermined light ink and dark ink has excellent clogging recovery performance, can suppress bleeding and beading, and can further suppress ink bleeding at the edge. Thus, it is possible to form an image in which the color gradation is expressed more naturally and beautifully.

Hereinafter, the embodiments of the present invention will be described more specifically by way of examples. However, the embodiments are not limited to these examples.

[Use ingredients]
The components used in the following examples and comparative examples are as follows.
[Pigment]
・ Cyan pigment (CI Pigment Blue 15: 3)
・ Yellow pigment (CI Pigment Yellow 74)
-Magenta pigment (CI Pigment Violet 19)
・ Black pigment (CI Pigment Black 7)
[Alkanediol]
・ 1,2-octanediol ・ 1,2-hexanediol [(poly) oxyalkylene glycol]
・ Dipropylene glycol (clogging prevention agent)
・ Glycerin (sugar)
・ HS-500 (Reduced starch saccharification product, manufactured by HAYASHIBARA SHOJI, INC.)
〔resin〕
・ Oxidized high-density polyethylene wax emulsion (AQUACER 515 [trade name], BY
(K company)
-Urethane resin (copolymer with a weight average molecular weight of 6,000 and an acid value of 50)
・ Sulfonate resin (see below)
・ Polyolefin resin (Chemipearl W4005 [trade name], manufactured by Mitsui Chemicals, Inc.)
Fluorene resin (containing about 50% by mass of a monomer having a fluorene skeleton represented by CAS No. 117344-32-8 as a monomer composition ratio, weight average molecular weight 3,300)
・ Styrene-acrylic acid resin (weight average molecular weight 1,600, acid value 150)

The sulfonic acid ester resin was prepared by the following method and will be described.
The following components were charged into a 2 liter beaker and stirred at 100 rpm for 10 minutes to obtain a monomer emulsion.
Ethylenically unsaturated monomer: 348 g (58 parts by mass) of methyl methacrylate
240 g of butyl acrylate (40 parts by mass)
Acrylic acid 12g (2 parts by mass)
Reactive emulsifier: 15% aqueous solution of Aqualon KH-10 30g
(Dai-ichi Kogyo Seiyaku Co., Ltd. trade name, sulfate group and polyoxyethylene group)
Chain transfer agent: 6 g of 2-ethylhexyl thioglycolate
Water: 450g

Next, 520 g of water and 90 g of an aqueous solution containing 15% of the same reactive emulsifier as above were put into a 2 liter separable flask, heated to 60 ° C. while stirring at 180 rpm, and then charged with 2 g of ammonium persulfate. This was heated up to 70 degreeC.

In the aqueous solution heated up to 70 ° C., the monomer emulsion obtained above was sequentially added for 3 hours while maintaining the polymerization temperature of 75 ° C. to carry out emulsion polymerization. Thereafter, the obtained polymer solution was heated to 80 ° C. and aged for 1 hour, and then cooled. Subsequently, the polymer solution after cooling was neutralized by adding a 10% aqueous ammonia solution to adjust the pH to 7.3.

Average particle diameter, minimum film-forming temperature, and weight average molecular weight of the resulting sulfonate resin (
Mw) was measured, the average particle diameter was 50 nm, the film forming temperature was 15 ° C., and Mw
Was 45,000. The average particle size is measured using Photo PAR-III (manufactured by OTSUKA ELECTRONICS CO., LTD.), And the minimum film-forming temperature is measured using a minimum film-forming temperature measuring machine (manufactured by Rigaku Corporation). Measured. In addition, the weight average molecular weight is determined by using a standard polystyrene as a calibration curve, GPC equipment (SC8010 (GPC) [trade name], Tosoh Co., Ltd.)
RPORATION.)). The measurement conditions were as follows.
Eluent: Tetrahydrofuran Column: G4000HXL (manufactured by Tosoh Corporation)
・ Flow rate: 1,000 μL / min ・ Column temperature: 40 ° C.
[Surfactant]
・ Polyorganosiloxane surfactant

The polyorganosiloxane surfactant used in Examples and Comparative Examples is the above-described chemical formula (I), wherein R is a methyl group, a is an integer of 9 to 13, and m is an integer of 2 to 4. In which n is an integer of 1 to 2 and in the above chemical formula (I), R is a hydrogen atom, a is an integer of 7 to 11, m is an integer of 30 to 50, n Is a surfactant comprising a compound having an integer of 3 to 5.

The polyorganosiloxane surfactant is 20% by mass of glycerin, 1, 2
-10% by weight of hexanediol, 0.1% by weight of the surfactant, and 69.9% by weight of water
1H using a bubble pressure dynamic surface tension meter BP2 (manufactured by KRUS)
When the dynamic surface tension of z (= 1 bubble / 1 second) was measured, the 1 Hz dynamic surface tension of the aqueous solution was 24.6 mN / m.

Here, in Table 1 below, “yellow” means C.I. I. Pigment yellow 74 and C.I. I.
Pigment Yellow 129 is mixed at a concentration ratio of 3: 1. Also, "Magenta"
Is C.I. I. Pigment Violet 19.

Moreover, the numerical value described in the column of saccharide | sugar and resin in the following Tables 1-5 is a value shown by solid content.

[Measurement item]
(Initial viscosity)
Shear rate 2 with dynamic viscoelasticity measuring device HAAKE MARS II (rheometer)
The viscosity of each ink at 50 s ^-1 was measured.

[Preparation of sample for TI measurement]
Stirring while maintaining the ink at 65 to 75 ° C., and measuring by volatilizing the solvent component contained in the ink so that the mass becomes 40% of the mass of the initial ink (ink before evaporation) Samples were prepared.
The reason why the ink in which the solvent component was volatilized was used as the measurement sample is as follows. Ink droplets deposited on the recording medium in actual printing are about 1 to 100 picoliters and are very small, so that the solvent component easily volatilizes. Therefore, when an ink drop in actual printing is used as a measurement sample, the ink drop causes a change in viscosity accompanying the drying behavior, and accurate measurement is difficult. Therefore, by measuring the volatilized solvent component contained in the ink droplet as an alternative sample, the T of the ink droplet is measured.
I can be measured accurately.

[TI]
For measurement sample prepared, the viscosity of each ink o'clock ^-1 o'clock and 1000s shear rate of 1s ^-1 was measured in the same manner as the initial viscosity, "the viscosity of at a shear rate of 1s ^-1 / shear rate 1
TI was calculated by “viscosity at 000 s ⁻¹ ”.
When the shear rate is slower than 1 s ⁻¹ , the ^value on the apparatus cannot be stabilized. 1000s ^-1
When it is faster, the ink spills from the measurement plate due to centrifugal force.

〔surface tension〕
The surface tension of each ink was measured by the Wilhelmy method using a fully automatic surface tension meter CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.).

[Dot diameter]
Measurement was performed at a magnification of 200 using MEASURING MICROSCOPE STM-UM (manufactured by OLYMPUS).

[Evaluation item]
[Clogging recovery evaluation]
Each ink prepared above was filled and mounted in an ink cartridge of an inkjet printer (PX-G930, manufactured by Seiko Epson). After that, using a printer driver, the printer head was filled with ink, and it was confirmed that normal recording was possible. Further, after moving the carriage to the ink cartridge replacement position, the outlet was disconnected, the ink cartridge was removed, and then the head was removed. Thus, after the ink cartridge and the head cap were removed, the head was left in an environment of 40 ° C. and 15% humidity for 1 day.
After leaving, install the head left on the carriage as it was, then install the ink cartridge that was left in the room temperature and humidity environment, and repeat the cleaning operation until all nozzles ejected to the same level as the initial stage. The ease of recovery was evaluated according to the following criteria.
A: The clogging is recovered by repeating the cleaning operation six times.
B: The clogging is recovered by repeating the cleaning operation 12 times.
C: The clogging does not recover even if the cleaning operation is repeated 12 times.

[Evaluation of occurrence of bleeding]
Each ink prepared above is mounted on an ink cartridge of an ink jet printer (PX-G930, manufactured by Seiko Epson Corporation), and is 720 dpi in the main scanning (head driving) direction.
In addition, recording can be performed at 360 dpi in the sub-scanning (recording medium conveyance) direction. Next, the voltage applied to the piezo element of the print head is adjusted so that the dot size upon landing is approximately 7 ng. One drive is 720 × 360 dpi, and OKT + (made by Oji Paper Co., Ltd.) of about 128 g / m ² A solid image of 720 × 720 dpi was recorded. Recorded at room temperature and humidity (25 ° C,
45% humidity). At this time, the ink adhesion amount of a single color duty of 100% was approximately 3.6 mg / inch ² .
The recorded image is an image in which 2 to 8 pixel ruled lines of the primary color of 80% duty are brought into contact with the primary color of 80% duty.
The obtained image was evaluated according to the following criteria.
A: A 6/720 inch ruled line can be reproduced without bleeding, but a 4/720 inch ruled line cannot be reproduced due to bleeding.
B: Although the 8/720 inch ruled line can be reproduced without bleeding, the 6/720 inch ruled line cannot be reproduced due to bleeding.
C: The 8/720 inch ruled line is bleeding and cannot be reproduced.

[Evaluation of occurrence of beading]
Each ink obtained above was mounted on an ink cartridge of an ink jet printer (PX-G930, manufactured by Seiko Epson Corporation).
The voltage applied to the piezo element of the print head was adjusted so that the dot size upon landing was 7 ng, and the dot interval by one main scan was set to be 720 × 360 dpi. 1
An image was recorded by applying ink to 28 g / m ² OKT + (manufactured by Oji Paper Co., Ltd.) with a resolution of 720 × 720 dpi. At this time, the ink adhesion amount of the single color duty 100% is 3.
It was 6 mg / inch ² .
Image recording was performed in an environment of 25 ° C. and 45% RH.
The obtained image was evaluated according to the following criteria.
A: Up to 100% duty can be reproduced without beading.
B: Up to 80% duty can be reproduced without beading.
C: 80% Duty, not reproduced without beading.

難水溶性のアルカンジオールと、樹脂と、所定濃度の色材と、を含み、表面張力が２１
〜２５ｍＮ／ｍであり、かつ、上記式（１）で表されるチキソトロピーインデックス（Ｔ
Ｉ）が２〜１１０であるインクジェット記録用インクにより、目詰まり回復性に優れ、か
つ、ブリーディング及びビーディングの発生をいずれも抑制できることが分かった。

Contains a slightly water-soluble alkanediol, a resin, and a coloring material having a predetermined concentration, and a surface tension of 21
Thixotropy index (T) represented by the above formula (1).
It was found that the ink for ink jet recording having I) of 2 to 110 is excellent in clogging recovery and can suppress the occurrence of bleeding and beading.

That is, the present invention is as follows.
[1]
Having a step of attaching ink jet recording ink to the coated paper;
The coated paper is at least one selected from the group consisting of finely coated paper, art paper, coated paper, matte paper, cast paper,
The ink jet recording ink contains a slightly water-soluble alkanediol, a resin, and a coloring material,
The content of the coloring material is 1 to 3% by mass with respect to the total mass of the ink,
The surface tension is 21-25 mN / m, and
4 by the evaporation of the ink represented by the following formula (1) with respect to the total mass before evaporation of the ink.
The thixotropy index (TI) at the time of 0 mass% is 2 to 110
Inkjet recording method.
TI = η (1 s ⁻¹ ) / η (1000 s ⁻¹ ) (1)
[2]
The inkjet recording method according to [1], wherein the thixotropy index is 4 to 110.
[3]
The resin is at least one of a polyolefin resin and a urethane resin;
The inkjet recording method according to [1] or [2] above.
[4]
The inkjet recording method according to any one of [1] to [3], wherein the initial viscosity is 3 to 10 mPa · s.
[5]
The step is a step of attaching the inkjet recording ink and an inkjet recording ink other than the inkjet recording ink to the coated paper,
Ink jet recording ink other than the ink jet recording ink contains a color material,
The inkjet recording method according to any one of [1] to [4], wherein the content of the coloring material is 5 to 7% by mass with respect to the total mass of the ink.

Claims (5)

An ink for ink jet recording comprising a hardly water-soluble alkanediol, a resin, and a coloring material,
The content of the coloring material is 1 to 3% by mass with respect to the total mass of the ink,
The surface tension is 21-25 mN / m, and
4 by the evaporation of the ink represented by the following formula (1) with respect to the total mass before evaporation of the ink.
An ink for ink jet recording having a thixotropy index (TI) of 2 to 110 at 0 mass%.
TI = η (1 s ⁻¹ ) / η (1000 s ⁻¹ ) (1) The ink for inkjet recording according to claim 1, wherein the thixotropic index is 4 to 110. The resin is at least one of a polyolefin resin and a urethane resin;
The ink for inkjet recording according to claim 1 or 2. The ink for inkjet recording of any one of Claims 1-3 whose initial viscosity is 3-10 mPa * s. Ink for inkjet recording according to any one of claims 1 to 4,
An inkjet recording ink containing a color material, wherein the content of the color material is 5 to 7% by mass relative to the total mass of the ink; and
An ink set for inkjet recording, comprising: