JP3249217B2 - Ink composition for inkjet recording - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer type ink jet printer for ejecting ink droplets from a recording head to form an ink image on a transfer medium and transferring the ink image to the recording medium to obtain an ink image on the recording medium. It relates to an ink composition.

[0002]

2. Description of the Related Art An example of the composition of an aqueous recording ink containing water, a colorant and a water-soluble resin as a conventional ink for ink jet recording of a type in which an ink droplet is ejected onto a recording medium to write a recorded image. Are described in JP-A-2-276874, JP-A-2-255875, etc., which aim to improve the stability of ejection from nozzles, the fixability on a recording medium, and the storage stability of ink. And

Further, Japanese Patent Publication No. 62-1426 and Japanese Patent Laid-Open No. 18462/1992 disclose water, pigment and water for the purpose of fixing an ink image on a recording medium, preventing ink bleeding and running. An ink composition example comprising an insoluble synthetic resin emulsion is described. Further, as examples of inks for transfer type printers, Japanese Patent Application Laid-Open (JP-A) No. 62-92949 and U.S. Pat. No. 4,538,156 describe examples of ink compositions comprising water, a dye and a polyhydric alcohol. In a conventional example of this transfer type recording method, an ink droplet is once ejected onto a transfer medium, and most of the water in the ink droplet is evaporated to transfer the concentrated ink onto a recording medium such as paper. This makes it possible to obtain high print quality without being affected by differences in recording media, and to improve the drying property of an ink image.

[0004]

However, the ink composition used in the conventional transfer type printer or the ink composition for ink jet recording of the type in which the recording image is written by directly discharging the ink on the conventional recording medium is transferred. When used in a liquid-jet printer, there are the following three problems.

The first problem is that when an ink image is formed by ejecting ink droplets onto a transfer medium having good releasability, a high-quality image free of ink repelling, flowing, and the like cannot be formed. In other words, transfer media with good release properties have low surface energy, so they repel water-based inks, and must be fixed while maintaining the shape and position of the ink image initially formed on the transfer medium. Could not.

The second problem is that, in order to realize good transfer without residual transfer or deformation of the ink image regardless of the time from ink discharge to transfer or the print pattern, the transfer pressing force is increased. It is.

The relationship between the state of concentration of an ink image using a conventional ink and the transfer pressure tends to increase as the ink image is concentrated. That is, if the concentration of the ink increases, the adhesiveness of the ink image decreases, and a large transfer pressure is required to transfer the ink image with low adhesiveness. Therefore, in order to transfer at a low pressure, it is necessary to make the concentration as low as possible within a range in which the tackiness capable of sufficiently transferring can be obtained.

On the other hand, in an actual apparatus, it is necessary to obtain a good concentrated state without transfer residue and deformation of an ink image in a short time. For this purpose, the transfer medium is heated by a heater to promote the evaporation of the solvent component of the ink. Let it. However, even if the amount of heat of the heater that heats the transfer medium is set to an appropriate value and the entire ink image on the transfer medium is in a concentrated state in which good transfer can be performed, scanning is performed with a single nozzle head or a multi-nozzle head. In addition, the time from ink ejection to transfer differs depending on the location, and a difference occurs in the concentration state. Furthermore, the concentrated state of the ink image varies depending on the print pattern of the ink image, that is, the amount of ink per unit area.

In order to obtain good transfer irrespective of such a difference in the concentration state, it is necessary to set a pressure value in accordance with the maximum concentration state of the ink image, and an excessive pressure is required. Was.

A third problem with the conventional recording method is that the printed matter lacks robustness such as abrasion resistance and water resistance.

In a conventional recording method using a water-based ink, a coloring material, a resin, and the like, which are components of the ink, are water-soluble or hydrophilic, and an ink image is formed on a recording medium. After being fixed, the ink image was disturbed by contact with water again.

Further, the mechanical strength of the dried ink component itself is low, and the adhesive strength of the recording medium is also low, so that the fixing strength of the ink image to the recording medium is low, and sufficient rub resistance cannot be obtained.

The present invention solves the above three problems. The object of the present invention is to form a high-quality image without repelling ink droplets on a transfer medium having good releasability, and to form a high-quality image from printing to transfer. It is possible to transfer a high-quality ink image obtained on a transfer medium under a low pressure onto a recording medium without being affected by time or a print pattern, and furthermore, fix the fixing strength on the recording medium. Another object of the present invention is to provide a new ink composition for inkjet recording which can obtain an ink image having excellent fastness.

[0014]

The ink composition for ink jet recording of the present invention is an ink composition used in a transfer type ink jet recording method having at least a heating means, comprising at least water, a coloring material, a thermoplastic resin, It is characterized by containing saccharides and surfactants.

[0015]

According to the ink composition of the present invention containing at least water, a coloring material, a thermoplastic resin, a saccharide and a surfactant, the ink contains a surfactant and a saccharide as an adhesive component, so that it can be transferred onto a transfer medium. A high-quality ink image with no repelling, run-out, etc. can be formed, and the heating means evaporates the water in the ink image on the transfer medium, so that uniform adhesiveness is obtained regardless of the elapsed time after printing or the printing pattern. Can be obtained. As a result, a high-quality ink image on the transfer medium can be transferred to the recording medium at low pressure without residual transfer or image deformation.

Further, when the thermoplastic resin added to the ink image transferred onto the recording medium is heated to a temperature higher than its thermal softening temperature, thermal melting temperature or film forming temperature, the ink is firmly adhered to paper. At the same time, a printed image having excellent fastness can be formed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, embodiments 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:
It is characterized by containing at least water, a coloring material, a thermoplastic resin, a saccharide, and a surfactant.

Conventionally, water has been mainly used as a solvent for inks because of its low viscosity, excellent safety, easy handling, low cost, and no odor. As the ink material, pure water or ultrapure water that has undergone a purification step such as ion exchange or distillation is desirable.

As the coloring material, pigments, water-soluble dyes, disperse dyes, and water-insoluble dyes (when kneaded and added with a thermoplastic resin) are used. Any agent that can be uniformly dispersed by the combined use of agents and the like can be used.

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; metals such as copper, iron (CI Pigment Black 11) and titanium oxide; aniline black (CI Pigment Black) And organic pigments such as 1). Further, C.I. I. Pigment Yellow 1 (Fast Yellow G), 3, 12 (Disazo Yellow AAA), 13,
14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 81, 83 (Disazo Yellow H)
R), 95, 97, 98, 100, 101, 104, 1
08, 109, 110, 117, 120, 138, 15
3, C.I. I. Pigment Orange 5, 13, 16, 1
7, 36, 43, 51, C.I. I. Pigment Red 1,
2, 3, 5, 17, 22 (brilliant first scarlet), 23, 31, 38, 48: 2 (permanent red 2B (Ba)), 48: 2 (permanent red 2B (C
a)), 48: 3 (permanent red 2B (Sr)), 48:
4 (permanent red 2B (Mn)), 49: 1, 52: 2,
53: 1, 57: 1 (Brilliant Carmine 6B), 60:
1, 63: 1, 63: 2, 64: 1, 81 (rhodamine 6G
Rake), 83, 88, 101 (Bengara), 104,
105, 106, 108 (cadmium red), 11
2, 114, 122 (quinacridone magenta), 12
3, 146, 149, 166, 168, 170, 17
2, 177, 178, 179, 185, 190, 19
3, 209, 219, C.I. I. Pigment Violet 1
(Rhodamine lake), 3, 5: 1, 16, 19 (quinacridone red), 23, 38, C.I. I. Pigment Blue 1, 2, 15 (Phthalocyanine Blue R), 15:
1, 15: 2, 15: 3 (phthalocyanine blue G), 1
5: 4, 15: 6 (phthalocyanine blue E), 16, 1
7: 127 (dark blue), 28 (cobalt blue), 29
(Ultra blue), 56, 60, 63, C.I. I. Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc., and other processed pigments such as graft carbon whose pigment surface is treated with a resin or the like can be used. The addition amount is 0.5 to 30
% By weight, more preferably 1.0 to 12% by weight. A pigment having a particle diameter of 25 μm or less is used, and a pigment composed of particles of 1 μm or less is more preferably used.

In order to uniformly disperse these coloring materials, a dispersing agent may be added to the pigment in an amount of 0.5 to 200 wt.
%, More preferably 1 to 50 wt.
%, Particularly preferably 10 to 30% by weight, and it is desirable that they are further dispersed by a ball mill or the like.

A typical example of the dispersant for dispersing the pigment used in the ink of the present invention is an acrylic resin. Specific examples of such an acrylic resin include, for example, a styrene-acrylic acid copolymer and an acrylic resin. Acid-alkyl acrylate copolymer, styrene-acrylic acid-
Acrylic acid alkyl ester copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene-α-methylstyrene-acryl Examples thereof include acid-alkyl acrylate copolymers and salts thereof.

In dissolving the dispersant in water, for example, 2-aminoisopropanol, triethanolamine, morpholine, aqueous ammonia, propylene glycol, isopropanol, or the like may be used as an auxiliary.

As the water-soluble dye used in the ink of the present invention, direct dyes, acid dyes, basic dyes, food dyes and the like are used. I. Direct Black 9,
17, 19, 22, 32, 51, 56, 62, 69, 7
7, 80, 91, 94, 97, 108, 112, 11
3, 114, 117, 118, 121, 122, 12
5, 132, 146, 154, 166, 168, 17
3, 199, C.I. I. Direct Red 2, 4, 9, 2
3, 26, 31, 39, 62, 63, 72, 75, 7
6, 79, 80, 81, 83, 84, 89, 92, 9
5, 111, 173, 184, 207, 211, 21
2,214,218,221,223,224,22
5, 226, 227, 232, 233, 240, 24
1, 242, 243, 247, C.I. I. Direct violet 7, 9, 47, 48, 51, 66, 90, 9
3, 94, 95, 98, 100, 101, C.I. I. Direct Yellow 8, 9, 11, 12, 27, 28, 2
9, 33, 35, 39, 41, 44, 50, 53, 5
8, 59, 68, 86, 87, 93, 95, 96, 9
8, 100, 106, 108, 109, 110, 13
0, 132, 142, 144, 161, 163, C.I.
I. Direct Blue 1, 10, 15, 22, 25, 5
5, 67, 68, 71, 76, 77, 78, 80, 8
4, 86, 87, 90, 98, 106, 108, 10
9, 151, 156, 158, 159, 160, 16
8, 189, 192, 193, 194, 199, 20
0, 201, 202, 203, 207, 211, 21
3, 214, 218, 225, 229, 236, 23
7, 244, 248, 249, 251, 252, 26
4, 270, 280, 288, 289, 291, C.I.
I. Acid Black 7, 24, 29, 48, 52:
1, 172, C.I. I. Acid Red 35, 42, 5
2, 57, 62, 80, 82, 111, 114, 11
8, 119, 127, 128, 131, 143, 15
1, 154, 158, 249, 254, 257, 26
1, 263, 266, 289, 299, 301, 30
5, 336, 337, 361, 396, 397, C.I.
I. Acid Violet 5, 34, 43, 47, 4
8, 90, 103, 126, C.I. I. Acid Yellow 17, 19, 23, 25, 39, 40, 42, 44, 4
9, 50, 61, 64, 76, 79, 110, 127,
135, 143, 151, 159, 169, 174, 1
90, 195, 196, 197, 199, 218, 21
9, 222, 227, C.I. I. Acid Blue 9, 2
5, 40, 41, 62, 72, 76, 78, 80, 8
2, 92, 106, 112, 113, 120, 127:
1, 129, 138, 143, 175, 181, 20
5, 207, 220, 221, 230, 232, 24
7, 258, 260, 264, 271, 277, 27
8, 279, 280, 288, 290, 326, C.I.
I. Reactive Black 4, 5, 8, 14, 21, 2
3, 26, 31, 32, 34, C.I. I. Reactive Red 3, 13, 17, 19, 21, 22, 23, 24,
29, 35, 37, 40, 41, 43, 45, 49, 5
5, C.I. I. Reactive Violet 1, 3, 4,
5, 6, 7, 8, 9, 16, 17, 22, 23, 24,
26, 27, 33, 34, C.I. I. Reactive Yellow 2, 3, 13, 14, 15, 17, 18, 23, 2
4, 25, 26, 27, 29, 35, 37, 41, 4
2, C.I. I. Reactive Blue 2, 3, 5, 8, 1
0, 13, 14, 15, 17, 18, 19, 21, 2
5, 26, 27, 28, 29, 38, C.I. I. Basic Black 8, C.I. I. Basic Red 12, 13,
14, 15, 18, 22, 23, 24, 25, 27, 2
9, 35, 36, 38, 39, 45, 46, C.I. I. Basic violet 1, 2, 3, 7, 10, 15, 1
6, 20, 21, 25, 27, 28, 35, 37, 3
9, 40, 48, C.I. I. Basic Yellow 1, 2,
4, 11, 13, 14, 15, 19, 21, 23, 2
4, 25, 28, 29, 32, 36, 39, 40, C.I.
I. Basic Blue 1, 3, 5, 7, 9, 22, 2
6, 41, 45, 46, 47, 54, 57, 60, 6
2, 65, 66, 69, 71, C.I. I. Food black is used, but is not limited thereto.

The disperse dye and the water-insoluble dye which are used by being dispersed in the ink of the present invention or mixed or dissolved in the resin include C.I. I. Solvent Black 3, 5, 22, C.I. I. Solvent yellow 19,
44, 98, 104, 105, 112, 113, 11
4, C.I. I. Solvent Red 8, 24, 71, 10
9, 152, 155, 176, 177, 179, C.I.
I. Solvent Blue 2, 11, 25, 78, 94, 9
5, C.I. I. Solvent Green 26, C.I. I. Solvent Orange 5, 40, 45, 72, 63, 68, 7
8, C.I. I. Solvent violet 13, 31, 3
2, 33, C.I. I. Daispers Yellow 3, 5, 56,
60, 64, 160, C.I. I. Disperse Red 4,
5, 60, 72, 73, 91, C.I. I. D. Sparse Blue 3, 7, 56, 60, 79, 198, C.I. I. Daispers Orange 13, 30, etc. are used, but are not limited thereto.

The amount of the dye is determined depending on the type of the dye, the type of the solvent component, the characteristics required for the ink, and the like.
The range is from 10 to 10% by weight, preferably from 0.5 to 5% by weight.

The thermoplastic resin used in the ink of the present invention has a heat softening temperature or a heat melting temperature of 50 ° C. to 150 ° C.
Are used, preferably those having a temperature of 60C to 100C are used, and one kind or a mixture of two or more kinds can be used. The addition amount thereof is preferably in a range of a thermoplastic resin: colorant ratio of 1: 0.1 to 0.2: 1. However, as the amount of addition increases, the viscosity of the ink also increases. Therefore, it is preferable to suppress the amount of addition to about 30% by weight based on the entire ink.

Examples of the thermoplastic resin include polyacrylic acid, polymethacrylic acid, polyethylacrylic acid, styrene-butadiene copolymer, butadiene copolymer, acrylonitrile-butadiene copolymer, chloroprene copolymer, and crosslinked acrylic. Resin, crosslinked styrene resin, fluororesin, vinylidene fluoride, benzoguanamine resin, phenol resin, polyolefin resin, cellulose, styrene-acryl copolymer, styrene-methacryl copolymer, polystyrene, styrene-acrylamide copolymer, n- Isobutyl acrylate, acrylonitrile,
Vinyl acetate, acrylamide, silicone resin, polyvinyl acetal, polyamide, rosin resin, polyethylene, polycarbonate, vinylidene chloride resin, polyvinyl alcohol, cellulose resin, epoxy resin, vinyl acetate resin, ethylene-vinyl acetate copolymer, vinyl acetate Examples include, but are not limited to, acrylic copolymers, vinyl chloride resins, polyurethanes, rosin esters, microgels, microemulsions, and the like.

The following are examples of low-molecular-weight thermoplastic resins that can be used in the ink of the present invention. For example, polyethylene wax, montan wax, alcohol wax, synthetic oxidized wax, α-olefin-maleic anhydride copolymer, animal and plant waxes such as carnauba wax, lanolin, paraffin wax, microcrystalline wax, etc., are transferred onto a recording medium. Any material having excellent robustness at the time of the treatment can be used.

The above-mentioned resin is a form in which colored resin particles integrated with a coloring material are dispersed in ink, a form in which only resin is dispersed as fine particles in ink, and an emulsion which is stabilized and dispersed in water. It is preferably added in the form of particles or the like. Furthermore, although these resins dry under normal temperature environment, it is desirable to form a powder or a brittle solid without forming a film, and when heated to a softening temperature, a melting temperature or a film forming temperature or higher, a strong solid is formed. It is desirable to form a highly water-resistant film. The saccharides used in the ink of the present invention include glucose, diose, maltitol, triose,
Tetroose, pentoose, hexose, heptose,
Octose, nonose, sucrose (sucrose),
Monosaccharides such as inositol, xylose, maltotriose, and galactose, disaccharides, trisaccharides, tetrasaccharides, polysaccharides and their derivatives such as sugar alcohols, reduced derivatives such as deoxy sugars, oxidized derivatives such as aldonic acid and uronic acid, and glycoethenes Saccharides such as dehydrated derivatives, amino sugars and thio sugars are exemplified. Polysaccharides refer to sugars in a broad sense, and also include substances widely existing in nature, such as alginic acid, dextrin, and cellulose.

These saccharides are used in the ink of the present invention.
The content ratio of sugar to thermoplastic resin is preferably used in the range of 1: 4 to 4: 1, and if the sugar content is too small, the ink image formed on the transfer medium will have low adhesion and uneven transfer. If the density is too large, the water resistance and scratch resistance of the printed matter will be reduced.

As the surfactant used in the ink of the present invention, one or more water-soluble anionic, cationic, amphoteric or nonionic surfactants can be added.

The amount of addition should be 0.5 to 10% by weight, preferably 1 to 8% by weight in order to secure sufficient wettability.

For example, as anionic surfactants, higher fatty acid salts, higher alkyl dicarboxylates, higher alcohol sulfates, higher alkyl sulfonates, alkyl benzene sulfonates, alkyl naphthalene sulfonates, salts of naphthalene sulfonic acids ( Na, K, Li, C
a) Polycondensate of formalin, condensate of higher fatty acid and amino acid, dialkyl sulfosuccinate, alkyl sulfosuccinate, naphthenate, etc., alkyl ether carboxylate, acylated peptide, α-olefin sulfonate, N -Acyl methyl taurine, alkyl ether sulfate, secondary higher alcohol ethoxy sulfate,
Polyoxyethylene alkyl phenyl ether sulfate,
Examples include, but are not limited to, monoglycosulfate, alkyl ether phosphate, alkyl phosphate, and the like.

Examples of the cationic surfactant include, but are not limited to, aliphatic amine salts, quaternary ammonium salts, sulfonium salts, and phosphonium salts.

The amphoteric surfactant includes, but is not limited to, carboxybetaine type, aminocarboxylate, lecithin and the like.

As the nonionic surfactant, fluorine-based surfactants,
Silicone, acrylic acid copolymer, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene secondary alcohol ether, polyoxyethylene sterol ether, polyoxyethylene lanolin derivative, ethylene oxide derivative of alkylphenol formalin condensate , Polyoxyethylene polyoxypropylene block polymer, polyoxyethylene polyoxypropylene alkyl ether, fatty acid ester type of polyoxyethylene compound, polyethylene oxide condensed polyethylene glycol fatty acid ester, fatty acid monoglyceride, polyglycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol Fatty acid esters, sucrose fatty acid esters, fatty acid alkanolamides, Polyoxyethylene fatty acid amide, polyoxyethylene alkylamine alkylamine oxides but not limited thereto.

In addition, if necessary, pH adjusters such as potassium dihydrogen phosphate and disodium hydrogen phosphate, benzoic acid, dichlorophene,
Hexachlorophen, sorbic acid, p-hydroxybenzoate, ethylenediaminetetraacetic acid (EDTA),
Sodium dehydroacetate, 1,2-benzothiazoline-3
-One, 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.

A hydrophilic, high-boiling, low-volatile solvent is added to the ink of the present invention in order to impart the effects of nozzle clogging resistance, moisture retention and dispersion stability. Examples of the hydrophilic high-boiling-point low-volatile solvent used in the present invention include glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, polyethylene glycol, and polypropylene glycol. Polyhydric alcohols are used, or their monoetherified products, dietherified products, esterified products such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether,
Diethylene glycol monoethyl ether, diethylene glycol monobutyl ether and the like are used.
Methyl 2-pyrrolidone, 1.3-dimethylimidazolidinone, monoethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, diethanolamine, N-n-butyldiethanolamine,
A water-soluble organic solvent such as a nitrogen-containing organic solvent such as triisopropanolamine or triethanolamine can be added within a range that does not cause printing flow or bleeding.

For the purpose of improving the drying property and fixing property of water as the main solvent, ethanol, propanol,
Highly volatile monohydric alcohols such as isopropanol and butanol, and relatively low volatile alcohols such as hexanol, heptanol and octanol can be added in small amounts.

The production of the ink was carried out according to the following procedure, but is not limited thereto. The aqueous dispersion composed of the colorant and the dispersant was dispersed in a ball mill, and it was confirmed by microscopic observation that the pigment particles were in a monodispersed state, and a thermoplastic resin, a saccharide, a surfactant, a hydrophilic high boiling point were added thereto. A low-volatile solvent is added, and the mixture is further mixed and stirred for 30 minutes to be completely homogeneously mixed.
After adding additives such as preservatives and confirming complete dissolution,
The dispersion was filtered through a membrane filter having a pore diameter of 10 μm to remove dust and coarse particles, thereby obtaining a recording ink. Finally, performing the filtration operation once more is effective in preventing the contamination of impurities.

Table 1 shows the composition of the ink composition of the present invention using the above-mentioned materials prepared by the above-mentioned production method.

[0044]

[Table 1] The physical properties of the above ink examples were all adjusted to the following ranges.

The ink viscosity is 50 m in order to ensure stable ejection from the head and stable ink supply to the head.
It is desirable that the pressure be Pa · sec or less, and more desirably 25 mPa · sec or less.

The contact angle between the ink and the transfer medium is preferably 60 ° or less in order to prevent repelling and flowing of the ink on the transfer medium and to form a high quality ink image. In addition, the surface tension of the ink is 45 to ensure wettability with the transfer medium.
dyne / cm or less.
5 dyne / cm or less is desirable.

The softening temperature, melting temperature or film forming temperature of the thermoplastic resin contained in the ink is desirably 60 ° C. to 120 ° C. in order not to make the amount of heat at the time of heat fixing to the recording medium excessive.

Table 1 shows the composition of the ink comparative example composition of the present invention.
Shown in A method for producing each ink comparative example composition is described below. Ink Comparative Example 1 An ink composition was prepared in the same manner as in Example 1 except that the thermoplastic resin was removed from the composition of Example 1 to obtain an ink. Ink Comparative Example 2 An ink composition was prepared in the same manner as in Example 1 except that the saccharide was removed from the composition of Example 1 to obtain an ink. Ink Comparative Example 3 An ink composition obtained by removing the surfactant from the composition of Example 1 was used.
An ink was prepared in the same manner as in Example 1 to obtain an ink.

Next, a printing test was performed using each of the above inks with a transfer type ink jet recording apparatus described below.

FIG. 1 is a perspective view showing a characteristic structure of a transfer type ink jet printer used in an embodiment of the present invention. FIG. 2 is a sectional view. Around the transfer drum 1 as a transfer medium, an ink jet recording head 2, a backup roller 3 as a transfer unit, and a cleaner 8 for removing adhering matter on the transfer drum as necessary are sequentially arranged from the upstream side in the rotation direction. I have. Further, inside the transfer drum 1, a heating means 7 is arranged between the recording head 2 and the backup roller 3, and further, a second heating means 9 for heating the ink image transferred onto the recording paper 6 as a recording medium. Is recording paper 6
Are located on the travel path.

The recording head 2 is an ink jet recording head using a piezoelectric element, and has a plurality of nozzles in the axial direction of the transfer drum 1. An ink container 21 is connected to the recording head 2, and ink is supplied as needed.

The transfer drum 1 is formed by laminating an elastic layer 12 made of silicone rubber around a metal tube 11. The elastic layer 12 is suitably made of a rubber material.
It is desirable to use a material having good heat-releasing properties and a good releasability material that easily peels off the ink image, and a silicone rubber, a fluororesin, a fluorosilicone rubber, or a modified product thereof is preferable. Other materials include chloroprene rubber, nitrile rubber, ethylene propylene rubber, natural rubber, styrene rubber, isoprene rubber, butadiene rubber,
Ethylene / propylene / butadiene polymer, nitrile butadiene rubber and the like can also be used.

The backup roller 3 is a metal roller made of aluminum, and is configured to be able to press and release the transfer drum 1 by a transfer pressure applying device (not shown). At the time of pressing, the transfer drum 1 rotates at the same speed as the peripheral speed of the transfer drum 1 via the recording paper 6 in the direction of arrow B in the figure. The transfer load is
It was about 0.6 kgf / cm to 1.5 kgf / cm.

The cleaner 8 is made of felt,
The transfer drum 1 is contacted with a predetermined pressure by a contact mechanism (not shown).

The heating means 7 comprises a rod-shaped halogen lamp 15
And a reflector 16 having an elliptical surface on the inner surface. The halogen lamp 15 is disposed at a first focal point of the reflector 16.

The second heating means 9 is composed of a heat roll 4 and a pressure roll 30 having a built-in heating means such as a ceramic heater, and the recording paper 6 is formed by a nip formed by the heat roll 4 and the pressure roll 30. Is guided by a guide plate (not shown) so as to pass through the section.

Next, the operation will be described.

First, the ink image writing process will be described.

FIG. 3 is a diagram showing how an ink image is written. In the ink image writing step, the backup roller 3 is controlled to be pressed against the surface of the transfer drum 1. The recording head 2 used in this embodiment is a linear recording head having nozzles over the entire printing area L 1, and performs one page of ink image writing with one rotation of the transfer drum 1. The ink droplets 5 are selectively ejected from the nozzles of the recording head 2 in accordance with a recording signal, and a desired ink image 50
To form At this time, since the surfactant contained in the ink can obtain an appropriate wettability of the ink on the transfer drum, a high-quality ink image without repelling or flowing can be formed.

Next, the ink image 50 (ink droplet 5) formed on the transfer drum 1 by the recording head 2 is heated by the heating means 7. The heating means 7 is controlled by a temperature detector (not shown) so as to fall within a predetermined temperature range. The ink image on the transfer drum 1 is heated to increase the solid component concentration and form a sticky film. This is because saccharides are contained in the ink composition. In the case of the conventional ink, the concentration varies depending on the time elapsed since printing and the printing pattern, and the adhesiveness differs. However, by using the ink of the present invention, almost no matter the elapsed time after printing or the printing pattern, almost one time is obtained. Such adhesiveness can be maintained. That is, the ink image 50 is heated to evaporate the water, but the ink image itself has an effect of maintaining sufficient tackiness without being affected by the concentration. Therefore, the heating amount of the heating means 7 is used to evaporate the water. By setting the heat amount to a sufficient value, uniform and uniform adhesiveness can be obtained regardless of the elapsed time after printing or the printing pattern.

Next, the transfer drum 1 and the backup roller 3
Then, the recording paper 6 is passed through the abutting portion, and the ink image 50 on the transfer drum 1 is transferred to the recording paper 6 by the applied pressure. At this time, since the ink image maintains uniform tackiness, it is not necessary to set the transfer pressure in the maximum concentrated state. Therefore, a high quality image can be obtained on the recording paper 6 at a low pressure.

Here, the low pressure means 1 kg weight / weight in order to reduce the size of the apparatus, reduce the cost of components such as the transfer drum 1 and the backup roller 3 and to improve the durability of the elastic layer on the surface of the transfer drum. cm or less, more preferably 0.6 kgf / cm or less.

The ink image pressure-transferred onto the recording paper 6 is
The second heating means 9 heats the thermoplastic resin contained in the ink to a temperature higher than the softening temperature or the film forming temperature. In this embodiment, the softening temperature of the thermoplastic resin contained in the ink,
The melting temperature or film forming temperature is 65 to 80 ° C., and the heating temperature of the second heating means 9 is set to 150 ° C.
The ink image 50 is heated by the second heating means 9 and is fused to the fibers of the recording paper 6 and, at the same time, the pressure is applied by the pressure roller 30, so that the ink adheres along the irregularities of the fibers, An ink image having excellent fastness can be obtained on the recording paper 6.

When the transfer drum 1 completes the transfer of the ink image onto the recording paper 6, the transfer drum 1 moves to a portion in contact with the cleaner 8 as it rotates, and the residual ink on the transfer drum 1 is removed.

The results of printing tests of the ink composition of the present invention and the ink composition of the comparative example using the above-described transfer type ink jet recording apparatus are shown below.

The evaluation conditions are as follows.

Time from printing to transfer Printing start section: 10 seconds Printing end section: 2 seconds Printing pattern Solid 1 dot continuous line, alternate dot line, transfer drum surface material Silicone resin 1. the image quality of the ink image formed on the transfer medium; 2. The relationship between the transfer pressure and transfer efficiency when transferring an ink image and the fastness of printed matter. 3. abrasion resistance; The four items of water resistance were evaluated. The evaluation criteria are as follows. 1. Image quality of ink image ejected on transfer medium ○: No image deformation such as repelling, flow, etc. △: Partially repelling, image flowing ×: Repelling, image flowing as a whole, Characters cannot be read. Relationship between transfer pressure and transfer efficiency Transfer pressure 0.6 kgf / cm: Easy device downsizing and cost reduction of parts 1.0 kgf / cm: Possible to downsize equipment and cost down 1.5 kgf / cm: Small device Transfer efficiency ○: Transfer efficiency is 100%, no transfer remains, no image deformation △: Transfer efficiency is 95-100%, partial transfer remains, image deformation occurs ×: Transfer efficiency occurs Clear density change, white spots,
2. Image deformation occurs. Abrasion resistance (1 minute after printing) ：: No background dirt even when strongly rubbed with a finger △: Background dirt that can be visually discriminated is generated when strongly rubbed with a finger ×: Visually even if lightly touched with a finger 3. The soil which can be distinguished is generated. Water resistance ○: The printed matter does not blur at all even if water is dripped on the printed matter △: The edge is blurred when water is dripped on the printed matter ×: The printed matter flows when the water is dripped on the printed matter Based on the above evaluation conditions and criteria, ink compositions 1 to
Table 2 shows the results of investigations using a transfer-type inkjet recording apparatus using Comparative Examples 1 and 2.

[0068]

[Table 2] As shown in the above table, when the ink composition of the present invention is used, a high-quality ink image without repelling, flowing, etc. can be formed on a transfer medium, and a high-quality ink image on a transfer medium can be formed at a low pressure. Was transferred to the recording medium without any transfer residue or image deformation. Further, a printed image having excellent fastness was formed on the recording paper.

On the other hand, in the case of using the ink comparative example, the ink was repelled on the transfer medium, the flow was generated, and the image quality was disturbed. Furthermore, with regard to the transfer efficiency, if the transfer pressure is low, the transfer efficiency differs depending on the time from printing to transfer and the print pattern, so that a good transfer efficiency cannot be obtained. I needed it. Further, sufficient performance could not be obtained in the fastness of the printed matter.

The above results indicate that the ink composition of the present invention
By containing a surfactant and a sugar in the ink, it is possible to form a high-quality ink image on a low surface tension transfer drum with excellent release properties, and to evaporate the water in the ink image on the transfer medium. A high-quality ink obtained on a transfer medium at a low pressure regardless of the time from printing to transfer or a print pattern of a high-quality image on the transfer medium because a uniform adhesive film is obtained. This is obtained by a novel effect that an image can be transferred to a recording medium. In addition, the thermoplastic resin is heated to a temperature higher than its thermal softening temperature, thermal melting temperature or image film temperature, and the ink is firmly adhered to paper to obtain an ink image having excellent film strength and fixing strength. This is obtained by a novel effect that is possible.

Further, when saccharides are contained in the ink,
It was also effective in improving the fixability of the ink image to the recording medium.

Further, in the ink composition for ink jet recording of the present invention, after the ink image is transferred onto a recording medium and then subjected to a heating step, in addition to the effects described above, sharpening of edges, uneven paper and other plain paper It is possible to improve the responsiveness and the quick drying property.

Further, in the transfer type ink jet recording method using the ink composition for ink jet recording of the present invention,
Since a plurality of inks can be overlapped on a transfer medium, application to a two-color printer, a multi-color printer, and a full-color printer is also possible.

[0074]

As described above, the ink composition for ink jet recording of the present invention contains at least water, a colorant, a thermoplastic resin, a saccharide and a surfactant, so that it can be transferred onto a transfer medium having good releasability. A high quality ink image without repelling, flowing, etc. can be formed, and the time from transfer printing to transfer,
It is possible to transfer a high-quality ink image obtained on a transfer medium under a low pressure onto a recording medium without being affected by the print pattern, and it is also robust with strong fixing strength on the recording medium This has the effect that an ink image having excellent properties can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a transfer type ink jet recording apparatus used for evaluating an ink composition example of an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a configuration of a transfer type ink jet recording apparatus used for evaluating an ink composition example of an example of the present invention.

[Explanation of symbols]

 1: transfer drum (transfer medium) 2: recording head 3: backup roller 5: ink image 6: recording paper (recording medium)

Continued on the front page. (72) Inventor: Satoru Yasuda, 138-1 Kokubunji, Okunino-cho, Himeji-shi, Hyogo Pref. In-company (56) References JP-A-62-92849 (JP, A) JP-A-53-53414 (JP, A) JP-A-4-110364 (JP, A) JP-A-4-18462 (JP, A JP-A-4-189876 (JP, A) JP-A-4-332775 (JP, A) JP-A-4-85375 (JP, A) JP-A-2-255875 (JP, A) JP-A-2- 276874 (JP, A) JP-A-56-28256 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 11/00-13/00 WPIDS (STN)

Claims (1)

(57) [Claims] 1. An ink composition for use in a transfer type ink jet recording method having at least a heating means, wherein the ink composition contains at least water, a coloring material, a thermoplastic resin, a saccharide, and a surfactant. Ink composition.