JP2007203693A - Inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording method having good adhesion with a printing surface and producing printed matter of high image quality even when a laminated printed matter having high printing density is created on a plain sheet of paper. <P>SOLUTION: The inkjet recording method uses an inkjet ink which contains at least water, aqueous organic solvents and pigment wherein the content of water is 10≥50 mass% of the total inkjet ink mass, and of the aqueous organic solvents, the SP value of the aqueous organic solvent predominantly contained therein, is ≥16.5 but <24.6, and the content of the solvent having such SP value is ≥40 mass% of the total inkjet ink by mass. After an image is formed on an uncoated paper, a laminate processing is performed on at least a printing surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet recording method, and more particularly to an ink jet recording method in which an image surface printed on plain paper is covered with a laminate film to form an ink jet image excellent in glossiness and water resistance.

  In recent years, the inkjet recording method can be easily and inexpensively produced images, and thus has been applied to various printing fields such as photographs, various printing, marking, and special printing such as color filters. In particular, inkjet recording devices that emit and control fine dots, inkjet ink with improved color reproduction range, durability, and emission suitability, and ink-jet ink absorbability, coloring material color development, surface gloss, etc. Using improved special paper, it is possible to obtain image quality comparable to silver halide photography.

  Images produced by inkjet are also widely used for display items such as outdoors and in stores.

  When a printed material to be displayed outdoors or in a store is produced, a method may be employed in which the printed surface of the recording medium after printing is laminated to improve its water resistance and increase the strength of the printed material itself. At the same time, gloss and special surface conditions can be imparted by lamination. For this reason, the laminate coating is useful in that a printed matter placed in an extreme environment such as a pop in a store can be easily produced. For example, an inkjet printer designed to perform laminate coating with a single apparatus has been disclosed (for example, see Patent Document 1).

  When performing laminate printing, the adhesion between the surface of the printed material and the laminate layer is a problem. At this time, the surface drying property of the printed matter and the smoothness of the surface of the printed matter are affected. For a printing paper provided with a laminate layer, an ink-jet ink receiving layer is provided on a support, and recording is performed on the printing paper by ink-jetting, and then a laminate layer is constructed (for example, see Patent Documents 2 and 3). . In such a case, the surface of the printed material can be quickly dried and the surface state of the printed material can be smooth, so that the adhesion of the laminate can proceed without unevenness and a clean image can be obtained.

  However, in an inkjet image recording system that requires dedicated paper, there are problems in that the recording media that can be used are limited and the cost of the recording media is increased. Even when printing paper having an ink-jet ink receiving layer is used, there is a problem that the surface of the receiving layer cracks during lamination depending on printing conditions and lamination conditions.

  When plain paper (uncoated paper) is used as the recording medium, the dryness (surface dryness) of the inkjet ink on the paper surface is poor, and in order to obtain the adhesion of the laminate to the paper, wait for the surface to dry. Lamination was necessary. In addition, for printed matter with a high concentration, the adhesiveness of the laminate may be further deteriorated due to a phenomenon such as curling or cockling caused by the ink-jet ink, and when it is severe, it may be wrinkled under the laminate layer.

  For this reason, in order not to cause wrinkles, it is necessary to reduce the amount of ink jetted into the ink jet, resulting in a decrease in printing density. Another method is to select thick paper so that cockling does not occur. However, since the drying property of the surface is not improved, a drying mechanism or drying method is necessary to obtain sufficient lamination adhesion. There was no change in the need for retention time for.

In addition, when an oil-based solvent is used as an ink-jet ink having a high surface drying property, a phenomenon occurs in which the ink-jet ink solvent left inside the laminated printed matter diffuses into the laminating equipment and the laminate layer becomes cloudy white. In addition, since the penetrability is high, in order to increase the printing density, a large amount of ink-jet ink must be driven, which spurs the cloudiness of the laminate layer.
JP-A-9-70960 Japanese Patent Laid-Open No. 11-301099 JP 2001-158092 A

  As described above, when laminating on plain paper, there is a problem that the adhesiveness between the laminate layer and the printing surface is not good and the appearance of the image is deteriorated. Alternatively, there is a problem that even if the adhesiveness is good, the laminate layer becomes clouded by the residual solvent of the inkjet ink when stored.

  An object of the present invention is to provide an ink jet recording method for producing a printed matter having good adhesion to the printing surface and high image quality even when a printed matter having a high printing density laminated on plain paper is produced.

  The above object of the present invention can be achieved by the following configuration.

  1. Water-soluble that contains at least water, a water-soluble organic solvent and a pigment, the water content is 10% by mass or more and less than 50% by mass of the total ink-jet ink mass, and contains the most water-soluble organic solvent. The SP value of the organic solvent is 16.5 or more and less than 24.6, and the content of the water-soluble organic solvent having the SP value of 16.5 or more and less than 24.6 is 40% by mass or more of the total inkjet ink mass. An ink jet recording method comprising: forming an image on uncoated paper using an ink jet ink, and then laminating at least a print surface.

  According to the present invention, even when a printed material having a high printing density laminated on plain paper is produced, an ink jet recording method for producing a printed material having good adhesion to the printing surface and high image quality can be provided.

  The present invention will be described in more detail. The present inventors have found that by using an ink-jet ink that satisfies the constitution of the present invention, the surface dryness and curl cockling of plain paper are good, and a high-density printed matter can be obtained. Furthermore, it was found that when the ink-jet ink solvent is within the range of the SP value, the solvent does not diffuse into the laminate material, and a high-quality laminate printed matter can be obtained.

First, it is assumed that the inkjet ink of the present invention is discharged onto uncoated paper. Uncoated paper refers to paper having a substantial coating amount on both sides of 12 g / m ² or less (classified as a coating material of fine coated paper or less in the production statistics of the Ministry of International Trade and Industry).

  Examples of the non-coated paper in the present invention include high-grade printing paper, intermediate-grade printing paper, low-grade printing paper, fine-coating printing paper, special printing paper such as high-quality colored paper, foam paper, PPC paper, and other information paper.

  The aqueous inkjet ink of the present invention contains at least water, a water-soluble organic solvent, and a pigment. Here, the water-soluble organic solvent is not particularly limited as long as it can be mixed with water. Two or more water-soluble organic solvents can be used in combination. Of the water-soluble organic solvents, the most water-soluble organic solvent has an SP value of 16.5 or more and less than 24.6, and further contains a water-soluble organic solvent having an SP value of 16.5 or more and less than 24.6 Preferably, the amount is 30% by mass or more of the total ink-jet ink mass. Since this solvent composition contains a large amount of a water-soluble organic solvent having a higher hydrophobicity than water, curling and cockling do not occur and surface drying is also high. Further, if the SP value of the water-soluble solvent is in the range of 16.5 or more and less than 24.6, there is no affinity for the laminate equipment, and the solvent does not diffuse.

  The solvent solubility parameter (SP value) in the present invention is a value represented by the square root of the molecular cohesive energy. F. Fedors, Polymer Engineering Science, 14, p147 (1974). The unit is (MPa) 1/2, and refers to the value at 25 ° C.

  Hereinafter, examples of water-soluble organic solvents having an SP value of 16.5 or more and less than 24.6 are shown together with the SP value. Needless to say, the present invention is not limited to this. The numerical values in parentheses below indicate SP values.

Ethylene glycol monomethyl ether (24.5)
Ethylene glycol monoethyl ether (23.5)
Ethylene glycol monobutyl ether (22.1)
Ethylene glycol monoisopropyl ether (22.3)
Diethylene glycol monomethyl ether (23.0)
Diethylene glycol monoethyl ether (22.4)
Diethylene glycol monobutyl ether (21.5)
Diethylene glycol diethyl ether (16.8)
Triethylene glycol monomethyl ether (22.1)
Triethylene glycol monoethyl ether (21.7)
Triethylene glycol monobutyl ether (21.1)
Propylene glycol monomethyl ether (23.0)
Propylene glycol monophenyl ether (24.2)
Dipropylene glycol monomethyl ether (21.3)
Tripropylene glycol monomethyl ether (20.4)
1,3-dimethyl-2-imidazolidinone (21.8)
In the inkjet ink of the present invention, various conventionally known water-soluble organic solvents can be used in combination with the water-soluble organic solvent having an SP value of 16.5 or more and less than 24.6.

  Examples of water-soluble organic solvents preferably used as the solvent used in combination include alcohols (for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, hexanol, cyclohexane). Hexanol, benzyl alcohol, etc.), polyhydric alcohols (eg, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, Thiodiglycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanedio , 1,2-pentanediol, 1,2-hexanediol, 1,2,6-hexanetriol, etc.), amines (eg, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine) , Morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc.), amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.), heterocyclic rings (for example, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexylpyrrolidone, 2-oxazolidone, etc.), sulfoxides For example, dimethyl sulfoxide, etc.), sulfones (e.g., sulfolane), urea, acetonitrile, and acetone.

  As the pigment that can be used in the present invention, conventionally known pigments can be used without particular limitation, and any of water-dispersible pigments, solvent-dispersible pigments, and the like can be used, for example, organic pigments such as insoluble pigments and lake pigments, An inorganic pigment such as carbon black can be preferably used. The pigment is present in a dispersed state in the ink-jet ink. The dispersion method may be any of self-dispersion, dispersion using a surfactant, polymer dispersion, and microcapsule dispersion. Capsule dispersion is particularly preferred from the standpoint of fixability.

  The insoluble pigment is not particularly limited. Dioxazine, thiazole, phthalocyanine, diketopyrrolopyrrole and the like are preferable.

  Specific pigments that can be preferably used include the following pigments.

  Examples of the magenta or red pigment include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. Pigment red 202, C.I. I. Pigment red 222, C.I. I. Pigment violet 19 and the like.

  Examples of the pigment for orange or yellow include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 15: 3, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 94, C.I. I. And CI Pigment Yellow 138.

  Examples of the pigment for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

  Examples of black pigments include C.I. I. Pigment black 1, C.I. I. Pigment black 6, C.I. I. Pigment black 7 and the like.

  The average particle diameter of the dispersed state of the pigment contained in the inkjet ink of the present invention is preferably 50 nm or more and less than 200 nm. If the average particle size of the pigment dispersion is less than 50 nm or 200 nm or more, the stability of the pigment dispersion tends to be poor, and the storage stability of the inkjet ink tends to deteriorate.

  The particle size of the pigment dispersion can be determined by a commercially available particle size measuring instrument using a dynamic light scattering method, an electrophoresis method, or the like. Accurate and often used.

  The pigment used in the present invention is preferably used after being dispersed by a disperser together with a dispersant and other necessary additives according to desired purposes. As the disperser, a conventionally known ball mill, sand mill, line mill, high-pressure homogenizer, or the like can be used. Among these, the particle size distribution of the ink-jet ink produced by dispersion with a sand mill is sharp and preferable. The material of the beads used for sand mill dispersion is preferably zirconia or zircon from the viewpoint of contamination of bead fragments and ionic components. Furthermore, the bead diameter is preferably 0.3 mm to 3 mm.

  In the inkjet ink of the present invention, it is preferable to use a polymer dispersant in the dispersion.

  The polymer dispersant referred to in the present invention has a polymer component having a molecular weight of 5000 or more and 200000 or less. The polymer dispersant is selected from styrene, styrene derivatives, vinyl naphthalene derivatives, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid and fumaric acid derivatives. Examples thereof include a block copolymer comprising at least one kind of monomer, a random copolymer and salts thereof, polyoxyalkylene, and polyoxyalkylene alkyl ether.

  In the case of an acidic polymer dispersant, it is preferably added after neutralization with a neutralizing base. Here, the neutralizing base is not particularly limited, but is preferably an organic base such as ammonia, monoethanolamine, diethanolamine, triethanolamine, or morpholine.

  Moreover, in this invention, it is preferable that the addition amount of a polymer dispersing agent is 10-100 mass% with respect to a pigment.

  In addition to the above description, the inkjet ink of the present invention is publicly known depending on the purpose of improving the emission stability, print head and ink cartridge compatibility, storage stability, image storage stability, and other various performances as necessary. Various additives such as polysaccharides, viscosity modifiers, specific resistance regulators, film forming agents, ultraviolet absorbers, antioxidants, anti-fading agents, anti-fouling agents, rust inhibitors, etc. For example, oil droplet fine particles such as liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicone oil, ultraviolet absorbers described in JP-A-57-74193, 57-87988, and 62-261476, JP-A-57-74192, JP-A-57-87989, JP-A-60-72785, JP-A-61-146591, JP-A-1-95091 and JP-A-3-13. 76, etc., and JP-A Nos. 59-42993, 59-52689, 62-280069, 61-242871, and JP-A-4-219266. Examples thereof include a fluorescent brightening agent.

  In the ink-jet ink of the present invention having the above structure, the surface tension of the ink-jet ink is preferably 25 to 40 mN / m at 25 ° C., more preferably 25 to 35 mN / m, still more preferably 30 to 35 mN. / M. In addition, the viscosity of the inkjet ink is preferably 1 to 40 mPa · s at 25 ° C., more preferably 5 to 40 mPa · s, and still more preferably 5 to 20 mPa · s.

  A preferred method of laminating in the present invention is to bond a transparent laminate film to the surface of the printed material, and it may or may not be heated at the time of bonding, but it is preferably heated to 50 ° C. or higher. An adhesive laminate film in which an adhesive is applied to the back surface of the transparent film is preferably used. As the material of the transparent film, it is preferable to use polyethylene, polypropylene, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyphenylene sulfite, polyether sulfone, polyvinyl chloride, or the like. The thickness of the transparent substrate is generally about 20 to 200 μm, preferably about 30 to 100 μm. These base materials include benzophenones such as 2-hydroxybenzophenone and 2,4-dihydroxybenzophenone, UV absorbers such as (2-hydroxyphenyl) benzotriazole and (2-hydroxyphenyl-5-methylphenyl) benzotriazole. May be included.

  For the pressure-sensitive adhesive or adhesive, a heat seal type or pressure sensitive adhesive type resin is used. As the resin, any of styrene, butadiene, acrylic, urethane and the like can be used. For example, an acrylic adhesive is preferable, for example, an acrylic monomer such as methyl methacrylate, ethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, N-methylolacrylamine, and an ethylene monomer or styrene copolymerizable therewith. Copolymers such as system monomers can be used.

  The laminate layer can provide gloss, water resistance of the image area, paper strength, etc. by simply covering the image surface, but it is also preferable to improve the water resistance of the paper by laminating the back side as required.

  In addition, it is preferable to perform the lamination after performing a dry layer with a hot wire or hot air.

  The laminating mechanism is preferably incorporated into a part of the printer from the viewpoint of simplicity. At this time, it is more preferable to have a drying mechanism between printing and lamination.

Example 1
[Preparation of pigment dispersion A]
After mixing 15 parts by mass of carbon black MA100 (manufactured by Mitsubishi Chemical Corporation) as a pigment, 15 parts by mass of Joncryl 501 as a dispersion resin, 5 parts by mass of tripropylene glycol monomethyl ether, and 65 parts by mass of water, a diameter of 0.5 mm was mixed. 200 parts by mass of zirconia beads were placed in a polypropylene plastic bottle and sealed, and dispersed for 5 hours with a paint shaker to obtain a black pigment dispersion A.

[Preparation of inkjet ink A]
A solvent and water were added to the plastic bottle containing the pigment dispersion A so as to have the following combination, and the mixture was stirred for about 30 minutes with a paint shaker. Thereafter, the beads were removed, and filtration and membrane deaeration treatment using a hollow fiber membrane were performed to prepare inkjet ink A.

Tripropylene glycol monomethyl ether 240 parts by weight Water 35 parts by weight Pigment dispersion A 100 parts by weight [Preparation of inkjet ink B]
A solvent and water were added to the plastic bottle containing the pigment dispersion A so as to have the following combination, and the mixture was stirred for about 30 minutes with a paint shaker. Thereafter, the beads were removed, and filtration and membrane deaeration treatment using a hollow fiber membrane were performed to prepare inkjet ink B.

Tripropylene glycol monomethyl ether 125 parts by mass Water 155 parts by mass Pigment dispersion A 100 parts by mass Tripropylene glycol monomethyl ether has an SP value of 20.4, which satisfies the requirements of the present invention.

[Preparation of inkjet ink C]
A solvent and water were added to the plastic bottle containing the pigment dispersion A so as to have the following combination, and the mixture was stirred for about 30 minutes with a paint shaker. Thereafter, the beads were removed, and filtration and membrane deaeration treatment using a hollow fiber membrane were performed to prepare inkjet ink C.

Dipropylene glycol monomethyl ether 240 parts by weight Water 35 parts by weight Pigment dispersion A 100 parts by weight The propylene glycol monomethyl ether has an SP value of 21.3, which satisfies the requirements of the present invention.

[Preparation of inkjet ink D]
A solvent and water were added to the plastic bottle containing the pigment dispersion A so as to have the following combination, and the mixture was stirred for about 30 minutes with a paint shaker. Thereafter, the beads were removed, and filtration and membrane deaeration treatment using a hollow fiber membrane were performed to prepare inkjet ink D.

Ethylene glycol 240 parts by mass Water 35 parts by mass Pigment dispersion A 100 parts by mass Ethylene glycol has an SP value of 32.2 and does not satisfy the SP value range that is a requirement of the present invention.

[Preparation of inkjet ink E]
Water was added to the plastic bottle containing the pigment dispersion A so that the following combination was obtained, and the mixture was stirred for about 30 minutes with a paint shaker. Thereafter, the beads were removed, and filtration and membrane deaeration treatment using a hollow fiber membrane were performed to prepare inkjet ink E.

Water 275 parts by mass Pigment dispersion A 100 parts by mass [Preparation of inkjet ink F]
A solvent and water were added to the plastic bottle containing the pigment dispersion A so as to have the following combination, and the mixture was stirred for about 30 minutes with a paint shaker. Thereafter, the beads were removed, and filtration and membrane deaeration treatment using a hollow fiber membrane were performed to prepare inkjet ink F.

Dipropylene glycol monomethyl ether 145 parts by mass Ethylene glycol 95 parts by mass Water 35 parts by mass Pigment dispersion A 100 parts by mass [Preparation of inkjet ink G]
A solvent and water were added to the plastic bottle containing the pigment dispersion A so as to have the following combination, and the mixture was stirred for about 30 minutes with a paint shaker. Thereafter, the beads were removed, and filtration and membrane deaeration treatment using a hollow fiber membrane were performed to prepare inkjet ink G.

Dipropylene glycol monomethyl ether 90 parts by mass Ethylene glycol 150 parts by mass Water 35 parts by mass Pigment dispersion A 100 parts by mass [Preparation of inkjet ink H]
20 parts by mass of soybean oil methyl, 35 parts by mass of isostearyl alcohol, and 30 parts by mass of naphthenic solvent were mixed, and 10 parts by mass of Solsperse 28000 (manufactured by Avicia) was dissolved in this, followed by Carmine 6B (Dainippon Ink Chemical Co., Ltd.). 5 parts by mass of Kogyo Co., Ltd. was added and stirred for 15 minutes. Thereafter, it was dispersed in a bead mill for about 20 minutes to obtain inkjet ink H.

  Any solvent contained in the inkjet ink H has an SP value of 16.5 or less.

[Preparation of inkjet ink I]
A solvent and water were added to the plastic bottle containing the pigment dispersion A so as to have the following combination, and the mixture was stirred for about 30 minutes with a paint shaker. Thereafter, the beads were removed, and filtration and membrane deaeration treatment using a hollow fiber membrane were performed to prepare inkjet ink I.

Tripropylene glycol monomethyl ether 160 parts by mass Dipropylene glycol monomethyl ether 95 parts by mass Water 20 parts by mass Pigment dispersion A 100 parts by mass [Image recording]
A line head type piezo type recording head in which the nozzle diameter is 25 μm, the number of nozzles is 512, and the nozzle resolution is 1440 dpi (dpi represents 1 inch, that is, the number of dots per 2.54 cm) is arranged in an array. Using a recording resolution of 1440 × 1440 dpi, an ink-jet ink adhesion amount of 10 ml / m ² , and an image size of 280 × 200 mm, using ink-jet inks A to H, A4 size Shiraoi Thick A solid image having an inkjet ink adhesion amount of 14 ml / m ² and an image size of 200 × 280 mm was printed on one surface of Sample Nos. 1 to 9 to obtain Samples 1 to 9.

Lamination A film (Avery) was laminated on each printed recorded matter, and the status of the printed matter was evaluated as follows. The laminate peeling was judged as follows.

○: No peeling of the laminate is observed. ×: Lamination of the laminate is observed even in part.

  Further, after measuring the sample concentration, the sample was stored for one week, and the concentration was measured again. Xrite 938 (Japanese lithographic equipment) was used for the concentration measurement, and the visual concentration in status A was used as a value. At this time, the ratio of the density decrease after storage to the density before storage was examined, and the state of the image was evaluated as follows to evaluate the cloudiness.

○: Density decrease is less than 99% Δ: Density decrease is 50% or more and less than 99% X: Density decrease is less than 50% Table 1 shows the evaluation results.

  From Table 1, it can be seen that when the ink jet recording method of the present invention is used, a high-quality printed matter laminated using uncoated paper is obtained.

  The same effect was obtained when an A4 size cartridge as shown in FIG. 9 was installed in an ink jet ink printer as described in JP-A-9-70960 and laminated simultaneously with printing.

Claims (1)

Water-soluble that contains at least water, a water-soluble organic solvent and a pigment, the water content is 10% by mass or more and less than 50% by mass of the total ink-jet ink mass, and contains the most water-soluble organic solvent. The SP value of the organic solvent is 16.5 or more and less than 24.6, and the content of the water-soluble organic solvent having the SP value of 16.5 or more and less than 24.6 is 40% by mass or more of the total inkjet ink mass. An ink jet recording method comprising: forming an image on uncoated paper using an ink jet ink, and then laminating at least a print surface.