JPH10110126A - Ink for ink-jet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject ink for providing dots having a dot diameter size capable of dealing with resolution from roughness to fineness free from bleeding, containing a thermoplastic resin emulsion and hexylene glycol. SOLUTION: This ink is used for ink-jet recording for jetting an ink from a printing head 76 to a recording medium heated by a heater 72 to form an ink image and to record and comprises (A) water, (B) a pigment, (C) a thermoplastic emulsion, (D) hexylene glycol and optionally further (E) a water-soluble polymer, (F) a polyhydric alcohol and (G) a surfactant. The ink preferably contains 1-10wt.% of the component D. Consequently, sufficient permeability of the component D to a recording medium is secured and the occurrence of defective drying of ink and deficiency of concentration by bleeding can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ink for ink jet recording.

[0002]

2. Description of the Related Art Conventionally, as a method for suppressing printing bleeding, Japanese Patent Application Laid-Open Nos.
As disclosed in JP-A-288042 and the like, there is known a means for attaching ink to a recording medium by an ink jet recording method and heating the recording medium at a specific temperature or higher.

As an ink composition containing a water-soluble resin and a resin emulsion in the ink, Japanese Patent Application Laid-Open No.
No. 462, Japanese Patent Application Laid-Open No. 5-148441, and the like disclose an ink composition intended to ensure the fixability to a recording medium while ensuring the ejection stability.

The present inventors have recently made improvements to the above prior art, using a unique ink composition containing a thermoplastic resin in the ink, and raising the temperature of the recording medium above its softening temperature. In addition to the prevention of printing bleeding, the inventors have found that the color development becomes clear.

[0005]

However, when printing is performed on a heated recording medium using the conventional ink, the thermoplastic resin in the ink is heated at a temperature higher than its softening temperature, and the solvent is heated. Evaporation and the phase change of the resin promptly increase the viscosity, which has the effect of obtaining a high-quality image.On the other hand, an inkjet printer having a function of printing at multiple resolutions has a size corresponding to various resolutions. There is a problem that a dot diameter cannot be obtained.
In particular, even when high-quality dots with no blur and fine resolution are obtained, the dot diameter becomes smaller than the required size at the coarse resolution, and there is a problem that a blank portion is generated. On the other hand, even if high resolution dots of sufficient size with rough resolution are obtained, the amount of printed ink is excessive at the fine resolution, and poor image quality such as poor drying and ink flow. The bottom has occurred.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and an object of the present invention is to provide an ink-jet printer having a function of printing at a plurality of resolutions with a dot diameter size that can correspond from a coarse resolution to a fine resolution. An object of the present invention is to provide an ink jet recording ink capable of obtaining dots without bleeding.

[0007]

According to the present invention, there is provided an ink jet recording ink which forms an ink image by ejecting ink droplets from a print head onto a heated recording medium and records the image. , A pigment, a thermoplastic resin emulsion, and hexylene glycol. More preferably, it contains 1 to 10% by weight of hexylene glycol.

The ink jet recording ink of the present invention is
It is characterized by further containing a water-soluble polymer, preferably, the water-soluble polymer is saccharose, maltitol, maltose, gluconic acid, sorbitol, mannitol,
It is characterized by being one or more saccharides selected from glucose.

The ink-jet recording ink of the present invention comprises:
It is characterized by further containing a polyhydric alcohol, preferably the polyhydric alcohol is glycerin, ethylene glycol, diethylene glycol, triethylene glycol,
It is one or more kinds selected from dipropylene glycol, 1, 2, and 6 hexanetriol.

The ink-jet recording ink of the present invention comprises:
It is characterized by containing 0.1 to 1 wt% of a surfactant.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the constitution of the ink for ink jet recording of the present invention will be described in detail.

The ink jet recording ink of the present invention comprises:
When printing on a recording medium in which the thermoplastic resin is heated at or above its softening temperature, the viscosity increases quickly due to the evaporation of the solvent in the ink and the phase change of the resin, resulting in a high-quality image. There is.

However, on the other hand, there is a problem that the dots are not spread and a large dot diameter is hardly obtained, while the effect of suppressing bleeding and whiskers is obtained. As a method of increasing the size of the dots, there is a method of increasing the amount of ink forming one dot. However, in such a case, an excessive amount of ink is printed, which causes problems such as poor drying and ink flow.

However, these problems can be solved by including hexylene glycol in the ink. In other words, simply changing the resolution and the distance to the adjacent dot changes the todd in accordance with the distance, and the required dot size can be obtained. Further, when the required dot size cannot be adjusted by the above method, in order to obtain a larger dot diameter, the amount of ink forming one dot is changed.
Dots of various sizes according to the resolution can be obtained, and even if the ink is excessively printed, an image can be formed without bleeding and without ink flow.

More specifically, when dots are being formed by evaporation of water and formation of a thermoplastic resin on a recording medium heated to a temperature higher than the softening temperature of the thermoplastic resin in the ink, By having an appropriate permeability into hexylene glycol paper, a penetration width corresponding to the distance between adjacent dots can be formed, so that a plurality of resolutions can be handled. To obtain an even larger dot diameter, the dot diameter increases by changing the amount of ink forming one dot.
By having a proper permeability into the hexylene glycol paper in the ink, excessive ink does not remain on the paper, and bleeding, which is a problem of the conventional example, and dots without ink flow can be obtained. In addition, by containing a water-soluble polymer, a polyhydric alcohol, and a surfactant, the spread of dots, bleeding, and the like can be adjusted more flexibly, and the flexibility of the corresponding dot size is further expanded. The content of hexylene glycol is preferably 1 to 10 wt%, more preferably 2 to 5 wt%. If the xylene glycol content is less than 1 wt%, sufficient permeability cannot be ensured, and if it exceeds 10 wt%, poor drying of the ink and insufficient density due to ink bleeding will occur.

Hereinafter, the constitution of the ink of the present invention will be specifically described.

Examples of the pigment that can be used in the ink of the present invention include organic pigments and inorganic pigments.
Furnace black, lamp black,
Carbon blacks (CI Pigment Black 7) such as acetylene black and channel black, or copper oxides and iron oxides (CI Pigment Black 1)
1), metals such as titanium oxide, aniline black (C.I.
I. And organic pigments such as CI Pigment Black 1).

Further, C.I. I. Pigment Yellow 1 (Fast Yellow G), 3, 12 (Sea Aso Yellow AA)
A), 13, 14, 17, 24, 34, 35, 37, 4
2 (yellow iron oxide), 53, 55, 81, 83 (Disease Yellow HR), 95, 97, 98, 100, 101, 104,
108, 109, 110, 117, 120, 138, 1
53, C.I. I. Pigment Red 1, 2, 3, 5, 1
7, 22 (Furiant Fast Scarlet), 23, 31, 38,
48: 2 (Power Managerlet 2B (Ba)), 48: 2 (Power Managerlet)
2B (Ca)), 48: 3 (Powermantlet 2B (Sr)), 48: 4 (Powermantlet 2B (Mn)), 49: 1, 52: 2, 53: 1,5
7: 1 (Furyant Carmine 6B), 60: 1, 63: 1, 63: 2,
64: 1, 81 (rota min 6G rake), 83, 88, 101
(Bengara), 104, 105, 106, 108 (Catmium Ret), 112, 114, 122 (Kinakuri Tohma Computer),
123, 146, 149, 166, 168, 170, 1
72, 177, 178, 179, 185, 190, 19
3, 209, 219, C.I. I. Pigment Blue 1,
2, 15 (Phthalocyanine Pure R), 15: 1, 15: 2, 15:
3 (phthalocyanine blue G), 15: 4, 15: 6 (phthalocyanine blue
E), 16, 17: 1, 56, 60, 63, etc. can be used. The above pigments can be used alone or in combination of two or more.

The amount of the pigment to be added is preferably 0.1 to 10% by weight, more preferably 0.5 to 5% by weight, based on the whole ink composition. By setting the content to 0.1 wt% or more, a sufficient print density can be secured. By setting the content to 10 wt% or less, high printing quality can be obtained without causing structural viscosity in the viscosity characteristics of the ink. Sufficient ejection stability indispensable to the above can be secured. Further, by setting the content to 0.5 to 5% by weight, particularly the durability of the ejection stability can be improved.

The particle size is not particularly limited, but the particle size (average particle size) is preferably 25 μm or less.
More preferably, it is 1 μm or less. By using a pigment having a particle size of 25 μm or less, the occurrence of clogging and the like can be suppressed, and more satisfactory ejection stability can be realized.

The ink composition according to the present invention contains a resin dispersant capable of stabilizing the pigment in the form of fine particles in the ink composition. Examples of the resin dispersant that can be used include, for example, a copolymer having a hydrophilic portion and a hydrophobic portion in a molecule, specifically, a styrene-acrylic acid copolymer resin and a styrene-acrylic acid ester copolymer. Coalesce, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylate copolymer, maleic acid copolymer, for example, styrene-maleic acid copolymer,
Acrylate / maleic acid copolymer, sulfonic acid-based dispersant, for example, acrylate / styrene sulfonic acid copolymer, styrene / methacrylsulfonic acid copolymer, or acrylate / allyl sulfonic acid copolymer, Alternatively, these salts can be raised. Among them, the weight average molecular weight (hereinafter simply referred to as molecular weight) is 160
It is preferable to use a copolymer resin having an acid value of 0 to 25000 and an acid value of 100 to 250, particularly a styrene / acrylic acid copolymer resin. When a copolymer resin having a molecular weight of 1600 to 25000 and an acid value other than 100 to 250, particularly a styrene / acrylic acid copolymer resin, is used, re-dispersibility when the ink composition is dried cannot be obtained, and cleaning is not possible. In some cases, it becomes difficult to obtain the characteristics, and the problem that the ejection stability cannot be ensured may occur.

Examples of the water-soluble polymer that can be used in the present ink include saccharides. For example, monosaccharides such as glucose, xylose, and arabinose; disaccharides such as saccharose and maltose; polysaccharides such as maltotriitol and starch; Alternatively, a plurality of types can be used. In addition, water-soluble resins such as polyvinyl alcohol, sodium alginate, and polyethylene oxide, and modified products thereof can also be used.

The ink composition of the present invention contains a polyhydric alcohol as a water-soluble organic solvent. Specific examples include glycerin, ethylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, 1,
One or more selected from 2,6 hexanetriols can be used. In addition, polyethylene glycol, polypropylene glycol, monoether compounds, dietherified compounds and esterified compounds of the above-mentioned polyhydric alcohols, for example, diethylene glycol monomethyl ether, or diethylene glycol monoethyl ether, diethylene glycol monobutyl, further N-methyl-2-pyrrolidone, monoethanol Amine, N, N-
Nitrogen-containing organic solvents such as dimethylethanolamine, N, N-diethylethanolamine, diethanolamine, and triethanolamine can also be used.

Further, a highly volatile monohydric alcohol such as ethanol, propanol, isopropanol, or butanol may be contained in a small amount with respect to water as a main solvent for the purpose of improving the drying property.

The thermoplastic resin emulsion that can be used in the present ink includes styrene acrylate copolymer, polyacrylate, polymethacrylate, polystyrene, polyethyl acrylate, and styrene butadiene copolymer. , Butadiene copolymer, acrylonitrile butadiene copolymer, chloroprene copolymer, crosslinked acrylic resin, crosslinked styrene resin, fluororesin, vinylidene fluoride, benzoguanamine resin, polyolefin resin, styrene-methacrylic acid ester copolymer, polystyrene , Styrene-acrylamide copolymer, n-isobutyl acrylate, acrylonitrile, vinyl acetate, acrylamide, polyvinyl acetal, rosin resin, polyethylene, vinylidene chloride resin, vinyl acetate Animals and plants such as resin, ethylene-vinyl acetate copolymer, vinyl acetate-acryl copolymer, vinyl chloride resin, polyethylene wax, montan wax, alcohol wax, synthetic oxidized wax, α-olefin-maleic anhydride copolymer, carnauba wax, etc. System wax, lanolin, paraffin wax, microcrystalline wax and the like can be used. The MFT of the above thermoplastic resin is preferably from 50 ° C to 100 ° C, more preferably from 65 ° C to 90 ° C, in order to reduce the energy required for heat fusion.

The content of the thermoplastic resin is preferably from 0.2 to 20% by weight, more preferably from 7 to 20% by weight, based on the whole ink composition. 0.2w content
By setting the content to t% or less, better printing quality can be ensured, and by setting the content to 20% by weight or less, the viscosity of the ink composition can be appropriately suppressed.

Surfactants that can be used in the present invention include anionic surfactants such as higher fatty acid salts,
Higher alkyl dicarboxylates, higher alcohol sulfates, higher alkyl sulfonates, alkyl benzene sulfonates, alkyl naphthalene sulfonates, naphthalene sulfonic acid salts (Na, K, Li, Ca) formalin polycondensates, higher fatty acids And condensates of amino acids, dialkyl sulfosuccinates, alkyl sulfosuccinates, naphthenates, etc., alkyl ether carboxylates, acylated peptides, α-olefin sulfonates,
N-acylmethyltaurine, alkyl ether sulfate,
Secondary higher alcohol ethoxy sulfate, monoglycol sulfate, alkyl ether phosphate ester salt, alkyl phosphate ester salt, polyoxyethylene alkyl ether sulfate ammonium salt, polyoxyethylene alkyl ether sulfate sodium salt, polyoxyethylene alkyl phenyl ether sulfate ammonium salt, poly Oxyethylene alkyl phenyl ether sulfate sodium salt, polyoxyethylene alkyl sulfate monoethanolamine,
Examples include ammonium polyoxyethylene alkyl ether phosphate, potassium potassium polyoxyethylene alkyl ether phosphate, diethanolamine polyoxyethylene alkyl ether phosphate, sodium alkylnaphthalene sulfonate, sodium lauryl sulfate and the like.

The nonionic surfactants include fluorine surfactants, silicone surfactants, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, polyoxyethylene alkyl phenyl ether, and sorbitan monostearate. ,
Examples include acetylene glycol, ethylene oxide adduct of acetylene glycol (acetylene glycol alcohol ethylene oxide), propylethanolamide, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, and the like.

The above-mentioned anionic surfactant and nonionic surfactant can be used alone or in combination. The type of the surfactant may be one type or a plurality of types. If the total amount of the surfactant is too large, the foaming property is increased, and there is a risk that the ejection stability is impaired. Therefore, the total amount is preferably 0.1 to 1% by weight, more preferably 0.1 to 0% by weight. 0.8wt%
It is. If the amount is more than 1 wt%, bubbling may become intense, and if it is less than 0.1 wt%, the spread of the ink on the recording medium may be insufficient.

Further, if necessary, a pH adjuster such as potassium dihydrogen phosphate and disodium hydrogen phosphate, and benzoic acid, dichlorophen, hexachlorophen, sorbic acid for the purpose of fungicide, preservation, rust prevention and the like. , P-hydroxybenzoic acid ester, ethylenediaminetetraacetic acid (EDT
A), sodium dehydroacetate, 1,2-bezothiazolin-3-one (product name: Proxel XLII (ICI
Manufactured)), 3,4-isothiazolin-3-one and the like. Further, urea, thiourea, ethylene urea and the like can be added for the purpose of preventing nozzle drying.

The physical properties of the ink composition according to the present invention can be appropriately controlled. According to a preferred embodiment of the present invention, the viscosity of the ink composition is preferably 25 mPa · sec or less, more preferably 10 mPa · sec. Below (25 ° C)
It is. By being in this range, the ink composition is stably ejected from the ink ejection head. The surface tension of the ink is appropriately controlled, but is preferably 30 to 50 mN / m (25 ° C.).
It is preferred that

The ink composition for ink-jet recording of the present invention is prepared by appropriately mixing the above-mentioned components in any order, dissolving and / or dispersing, and then removing impurities by filtration. In particular, it is preferable to prepare an aqueous pigment dispersion from a pigment, a resin dispersant, and water, and mix the pigment dispersion with other components such as a thermoplastic resin emulsion.

Further, a pigment is appropriately selected, and if necessary, other compounding components are appropriately selected in combination with the selected pigment, to thereby prepare a yellow ink composition and a magenta ink composition according to the present invention for color ink jet recording. , A cyan ink composition, a black ink composition, and the like.

[0034]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples. In the following examples, the mixing ratio is by weight.

1. Preparation of Pigment Dispersion Styrene-acrylic acid copolymer (weight average molecular weight 25
000, acid value 200) 4 parts of resin, 2.7 parts of triethanolamine, 0.4 part of isopropyl alcohol, and 72.9 parts of ion-exchanged water are completely dissolved under heating at 70 ° C.

Next, 20 parts of carbon black MA-100 (manufactured by Mitsubishi Kasei Co., Ltd.) were added, and after premixing, the mixture was dispersed with an Eiger mill (manufactured by Eiger Japan) until the average particle diameter of the pigment became 100 nm. (Bead filling rate 70%, media diameter 0.7 mm).

The desired pigment dispersion was obtained.

2. Preparation of Ink Next, the preparation of the ink of Example 1 of the present invention using the dispersion will be described.

The above dispersion 10 wt% Hexylene glycol 2 wt% Styrene / acrylic ester emulsion (as solid) 7 wt% Diethylene glycol 7 wt% Maltitol (as solid) 8 wt% Anionic surfactant 0.3 wt% (polyoxy Ethylene alkyl phenyl ether sulfate ammonium salt) Ion-exchanged water residue The styrene / acrylic ester emulsion is an aqueous dispersion having a solid content of 50.0%, and maltitol is an aqueous solution having a solid content of 80%. The value was expressed as a solid content value.

After mixing the above components, the mixture was passed through a metal mesh filter (Twill weave 2300 mesh manufactured by Manabe Industries Co., Ltd.) to obtain an ink of Example 1 of the present invention.

<Examples 2 to 8> By repeating the production method described in Example 1 except that the components shown in Table 1 below were used in the amounts shown in Table 1 below, An ink composition for inkjet recording according to the invention was obtained.

[0042]

[Table 1]

As a comparative example of the present invention, an ink composed of water, a pigment, a water-soluble resin, a microemulsion, and a water-soluble organic solvent of a conventional example was prepared.

Next, the ink used in the evaluation of the ink, that is, the ink is ejected from the ink jet recording head and adhered to the recording medium. At the same time, the ink is ejected from the recording medium support (for example, a platen) via the recording medium. The ink jet recording in which fixing is performed by applying heat to ink composition droplets will be described in detail.

The ink composition according to the present invention can be housed in a conventional ink cartridge and inserted into a conventional ink jet recording apparatus to perform ink jet recording. In addition, at least one of the yellow ink composition, the magenta ink composition, the cyan ink composition, the black ink composition, and the like (preferably all of the ink compositions) is used as the ink composition of the present invention and contains the magenta ink. An ink cartridge, the ink cartridge containing yellow ink, the ink cartridge containing cyan ink, and optionally the ink cartridge containing black ink, are inserted in combination, or magenta ink. ,
Color ink jet recording can be carried out using a color ink jet recording apparatus in which an ink cartridge for accommodating yellow ink, cyan ink and, in some cases, black ink in separately partitioned fractions is inserted.

The heating temperature of the platen is preferably about 80 ° C.
~ 120 ° C. If the temperature is lower than 80 ° C, insufficient drying and insufficient fixing may occur. If the temperature is higher than 120 ° C, excessive energy may be required.

The ink jet recording apparatus used for evaluating the ink for ink jet recording of the present invention will be described in more detail with reference to the drawings.

FIG. 1 shows an ink jet recording apparatus used for evaluating the ink for ink jet recording of the present invention.

In the figure, a platen 71 serves as a means for heating the recording medium and a means for conveying the recording medium. The platen 71 is a cylinder made of a metal having high heat conductivity, for example, aluminum, and is rotated by a driving device (not shown) in the direction of the arrow in the figure. This platen 7
The surface of 1 may be constituted by laminating silicone rubber or the like. Further, a heater 72 is disposed inside the platen 71 and heats the platen 71. Further, paper press rollers 73 and 74 are pressed against the platen 71, and a recording medium 75 is placed between the platen 71 and the paper press rollers 73 and 74. Conveyed. Paper press roller 73
Is constituted by bonding acrylonitrile rubber to the surface of a metal core material, for example.

The ink jet recording head 76 is located at a position facing the platen 71 with the recording medium 75 interposed therebetween.
Is placed. The recording head 76 may be one that forms droplets by a piezoelectric element or one that forms droplets by thermal energy. This recording head 7
No. 6 has 48 nozzles arranged in an arbitrary matrix. The nozzles of the recording head 76 eject ink droplets based on print data given by a processing unit (not shown). The recording head 76 includes an ink tank 7.
7, the recording head driving device 78
Thus, the recording medium can be moved in a direction perpendicular to the direction in which the recording medium is fed.

The ink jet recording is performed as follows. First, the recording medium 75 is conveyed while being sandwiched between the platen 71 and the paper pressing rollers 73 and 74. While being conveyed, the recording medium 75 contacts the platen 71 heated by the heater 72 and is heated. Therefore, in the apparatus of this aspect, the temperature of the surface of the platen 71 is controlled such that the temperature of the recording medium 75 is equal to or higher than the softening temperature of the thermoplastic resin. Next transported recording medium 7
5, ink droplets are selectively ejected by the recording head 76 in accordance with the print pattern. The ink droplets adhered to the recording medium are heated and turned into a film to form an ink dot. Next, the platen 71 and the paper pressing rollers 73 and 74
And the recording medium is conveyed by a predetermined amount.
6, the recording is performed. Here, when the ink dots are formed adjacent to each other or overlapped with each other, it is preferable that printing is performed with a fixed printing interval. After necessary recording is performed on the recording medium 75, the recording medium 75 is discharged from the apparatus.

In this apparatus, the distance between the ink jet recording head and the platen is about 1.5 mm, the temperature of the ink jet recording head is generally 40 ° C. to 50 ° C., and the surface temperature of the platen 71 is about 120 ° C. The surface temperature of the recording medium was from 80 ° C to 120 ° C. The characteristics required for the ink from this temperature environment include a moisturizing effect at the temperature in the head, no viscosity increase due to drying and the like, and an ejection stability can be ensured. The solid content concentration of the non-evaporable component contained at 23 wt% or more sharply rises and the viscosity increases, so that the ink is fixed without bleeding and without drying unevenness.

FIG. 2 shows a recording apparatus according to the present invention. In this apparatus, the same elements as those of the apparatus of FIG. 1 are denoted by the same reference numerals as those of FIG. In this apparatus, a recording head is provided for each color of the ink composition. That is, the recording heads 81, 82, 83, and 84 are respectively provided with black ink, magenta ink,
The recording head ejects cyan ink and yellow ink. The ink is supplied from the ink tank 77 to the recording heads.

The printing by the apparatus of FIG. 2 is basically the same as the printing by the apparatus of FIG. That is, the recording medium 75 is moved by the recording medium winding device 85 to the platen 71.
Wrapped around. Next, one or more rows are printed by the recording heads 81 to 84. Next, the recording head 78 is moved by a predetermined amount, and one or more rows are printed. By repeating this, an image is recorded on the recording medium 75.

The print resolution is 360 dpi and 600 dpi
Printed in two types. The ejection conditions were adjusted so that the ejection ink amount could be ejected in two stages of 70 ng and 50 ng.

Subsequently, the evaluation results of the formed dot diameter and the degree of bleeding of the image printed with the ink composition of the present invention at the above two types of resolution and the above two types of ink ejection amounts are shown. Show.

Recycled paper and copy paper were used as recording paper. In addition, the evaluation was performed using two types of evaluations, that is, a single-color evaluation of the inks of Examples 1 to 8 and a full-color print pattern in which the four-color inks of Examples 1 to 4 and Examples 5 to 8 were superimposed and printed. .

The evaluation was made by the following level judgment.

(1) Dot Diameter of Printed Image and Solid Print Quality A: A sufficient dot diameter corresponding to the resolution is obtained.
The solid part is evenly buried. ：: A sufficient dot diameter corresponding to the resolution was obtained, but the solid portion was partially non-uniform. ×: A sufficient dot diameter corresponding to the resolution was not obtained, and a solid portion had a blank portion.

(2) Bleeding of dots of printed image and ink flow A: Bleeding, no ink flow ：: Bleeding, slight ink flow, but no problem in image quality. ×: Bleeding, ink flow, problematic in image quality.

[0061]

[Table 2]

From the above results, by using the inkjet recording ink of the present invention containing hexylene glycol in the ink, dots of various sizes corresponding to the resolution can be obtained, and an image without bleeding and without ink flow can be obtained. Can be formed.

[0063]

According to the present invention, by using an ink jet recording ink containing hexylene glycol in the ink, dots are evaporated on the recording medium heated above the softening temperature of the thermoplastic resin in the ink, and the thermoplastic resin is removed. When the hexylene glycol in the ink has an appropriate spread on the paper in the paper during the formation of the film, a dot having a dot diameter corresponding to the resolution can be formed. Further, when the dot diameter is increased by changing the amount of ink for one dot, the hexylene glycol in the ink has an appropriate permeability into the paper, so that no excessive ink remains on the paper, and ink bleeds. This has the effect that dots without ink flow can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of an inkjet recording apparatus used for evaluating an inkjet recording ink of the present invention.

FIG. 2 is a schematic view of an inkjet recording apparatus used for evaluating the inkjet recording ink of the present invention.

[Explanation of symbols]

 71: platen 72: heater 73: paper pressing roller 74: paper pressing roller 75: recording paper (recording medium) 76: recording head 77: ink tank 78: recording head driving device 81: recording head (black ink) 82: recording head (Magenta ink) 83: recording head (cyan ink) 84: recording head (yellow ink) 85: recording medium winding device

Claims (7)

[Claims] 1. An ink jet recording ink for forming an ink image by ejecting ink droplets from a print head onto a recording medium heated, and recording the ink image, comprising at least water, a pigment, a thermoplastic resin emulsion, and hexylene. Ink jet recording ink containing glycol. 2. The hexylene glycol is added in an amount of 1 to 10 w.
The ink for ink-jet recording according to claim 1, which contains t%. 3. The ink jet recording ink according to claim 1, further comprising a water-soluble polymer. 4. The method according to claim 1, wherein the water-soluble polymer is saccharose, maltitol, maltose, gluconic acid, sorbitol,
4. The ink jet recording ink according to claim 3, which is one or more saccharides selected from mannitol and glucose. 5. The ink jet recording ink according to claim 1, further comprising a polyhydric alcohol. 6. The inkjet according to claim 5, wherein the polyhydric alcohol is one or more kinds selected from glycerin, ethylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, 1, 2, 6 hexanetriol. Recording ink. 7. The ink for ink-jet recording according to claim 1, comprising 0.1 to 1 wt% of a surfactant.