JP2008138045A - Ink set, inkjet recording method and recorded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink set having two liquids-mixing type photoradical curing type ink composition hardly causing blotting and color bleed, and to provide an inkjet recording method and a recorded product. <P>SOLUTION: The ink set has an ink composition A at least containing an electrolyte, a radically polymerizable compound and a photopolymerization initiator, and an ink composition B at least containing a coloring agent and a polymerizable compound. The inkjet recording method by using the ink set, and the recorded product are also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink set, an ink jet recording method, and a recorded matter, and more specifically, an ink set including a two-component mixed photoradical curable ink composition, and a two-component mixed photoradical curable type free from bleeding and color bleeding. The present invention relates to an ink set including an ink composition, an ink jet recording method, and a recorded matter.

  The ink jet recording method is a printing method in which printing is performed by causing a droplet of an ink composition to fly and adhere to a recording medium such as paper. This method has a feature that a high-resolution and high-quality image can be printed at a high speed with a relatively inexpensive apparatus. In general, an ink composition that is usually used for ink jet recording contains water as a main component and contains a coloring component and a wetting agent such as glycerin for the purpose of preventing clogging.

  On the other hand, as an ink jet recording method, there has been proposed a method of applying an ink composition containing a dye having at least one carboxyl group after applying a polyvalent metal salt solution to a recording medium (for example, Patent Document 1). In this method, an insoluble complex is formed from a polyvalent metal ion and a dye, and the presence of this complex is said to provide a high-quality image having water resistance and no color bleeding.

  Further, by using a combination of a color ink containing a surfactant or a penetrating solvent and a salt that imparts at least permeability and a black ink that thickens or aggregates due to the action of this salt, the image density is increased. There has also been a proposal that a high-quality color image without color bleeding can be obtained (Patent Document 2). That is, an ink jet recording method has been proposed in which a good image can be obtained by printing two liquids, a first liquid containing salt and an ink composition.

  In addition, an ink jet recording method for printing two liquids has been proposed. For example, when either one of the ink composition or the reaction liquid contains an oligomer, the other contains a monomer, whereby an ink jet recording method (Patent Document 3) that imparts good printing characteristics and abrasion resistance, When either the ink composition or the reaction liquid contains an oligomer, the other contains a monomer, and the ink composition is adhered to the recording medium prior to the reaction liquid, so that good printing characteristics and abrasion resistance can be obtained. An ink jet recording method (Patent Document 4) that imparts properties has been proposed (others include Patent Documents 5 and 6).

  Such a photo-radical curable ink-jet ink has good storage stability, safety, low energy for curing and fixing, and excellent chemical resistance, mechanical strength, and adhesion of an image that can be formed on a recording medium. Is required.

On the other hand, Non-Patent Document 1 discloses a technique using a dendrimer. A dendrimer is one of dendritic polymers (dendritic polymers), and the dendritic polymers can be roughly classified into six structures as shown below.
1. Dendrimer2. 2. Linear dendritic polymer Dendrigraft polymer4. 4. Hyperbranched polymer 5. Star hyperbranched polymer Hypergraft polymer

  Among these, 1 to 3 have a degree of branching (DB) of 1 and have a defect-free structure, while 4 to 6 have a random branch structure that may contain defects. is doing. In particular, dendrimers can be arranged with high density and concentration of reactive functional groups on the outermost surface as compared with generally used linear polymers. Expectation is high. Moreover, even if the hyperbranched polymer is not as large as a dendrimer, it is possible to introduce many reactive functional groups on the outermost surface thereof.

  Unlike conventional linear polymers and branched polymers, these dendritic polymers are highly branched by repeating a three-dimensional branched structure. Therefore, it is possible to keep the viscosity of the ink composition low compared with a linear polymer having the same molecular weight.

  However, the dendrimer disclosed in Non-Patent Document 1 has insufficient structure control, and the ink viscosity at 25 ° C. is 30 mPa · s or more, although only 3% by weight is added to the ink composition. End up. Also, unless the ink jet head and the ink composition are heated to raise the ink viscosity to 10 mPa · s or less, which is the viscosity of a normal ink jet ink, printing is difficult and ejection failures frequently occur. When the ink-jet head and the ink composition are heated and heated, it is inevitable that the reliability of the ink is lowered due to the progress of the thermal polymerization reaction, and the members constituting the printing apparatus are deteriorated.

  For the purpose of reducing the viscosity, a low-viscosity diluent, that is, an organic solvent that does not have a polymerizable functional group or water is also added, but adding a component that does not participate in such a curing reaction, This is not preferable because it increases the load on the process, for example, it is necessary to perform a drying process by means such as heating or blowing as a pretreatment for the curing reaction, or a special process such as providing an absorption layer on the recording medium. .

  In this case, if the curing reaction is performed with an insufficient drying step, the residual solvent and residual moisture are foamed by the polymerization heat, or are pushed out of the cured product and bleed out to remain on the surface of the cured film. Causes stickiness.

  Further, it is obvious that no significant improvement in characteristics can be expected if the amount added to the ink composition is very small.

  In addition, when a polymerizable functional group is not introduced on the surface of these dendrimers and hyperbranched polymers, the film strength is reduced by phase separation and bleeding out after the curing reaction.

Furthermore, the photo-radical curable ink composition often has storage stability problems, that is, problems such as increase in viscosity and generation of gel during the storage period. This is because the ink itself has chemical reactivity, which is an essential problem. It is self-evident that substances with higher curing reactivity have lower storage stability. Therefore, if a large amount of a thermal polymerization inhibitor that inhibits a storage-stable dark reaction is added to the ink composition, the polymerization reaction during the curing reaction is inhibited, and good image formation becomes difficult. In particular, dendrimers and hyperbranched polymers have a molecular structure in which polymerizable functional groups are densely and concentratedly arranged on the outermost surface, and it is an important issue to impart further storage stability.
JP-A-5-202328 JP-A-6-106735 JP 2000-119574 A JP 2000-158793 A JP-A-3-240557 JP-A-3-240558 Keigo Aoi et al., “Dendritic Polymers: A World of High Functionality Expanded by Multi-Branched Structures”, NTS Corporation, October 31, 2005

  Inventors of the present invention have recently squeezed an ink composition containing an electrolyte and an ink composition containing a colorant on a recording medium in an ink set equipped with a two-component mixed radical polymerization type ink. And the knowledge that a good image with suppressed color bleeding can be realized. The present invention is based on such knowledge.

  Accordingly, an object of the present invention is to provide an ink set, an ink jet recording method, and a recorded matter provided with a two-component mixed photoradical curable ink composition free from bleeding and color bleeding.

  The present invention provides the following inventions. [1] An ink comprising an ink composition A containing at least an electrolyte, a polymerizable compound, and a photopolymerization initiator, and an ink composition B containing at least a colorant and a polymerizable compound. Composition set.

  Preferred embodiments of the invention are as follows. [2] The ink set according to [1], wherein the ink compositions A and B are composed of only a non-volatile substance;

  [3] The ink according to [1] or [2], wherein the electrolyte is selected from the group consisting of an anionic polymer electrolyte, a cationic polymer electrolyte, and an amphoteric polymer electrolyte. set;

  [4] The ink set according to [3], wherein the anionic polymer electrolyte is a polycarboxylic acid;

  [5] The ink set according to [3], wherein the cationic polymer electrolyte is a polyamine;

  [6] The ink set according to [3], wherein the amphoteric polymer electrolyte is an amino acid;

  [7] The ink set according to any one of [1] to [6], wherein the polymerizable compound is ethylene glycol monoallyl ether and / or an N-vinyl compound;

  [8] The ink set according to [7], wherein the N-vinyl compound is N-vinylformamide;

  [9] The ink set according to any one of [1] to [8], wherein the polymerizable compound is a dendritic polymer;

  [10] The ink set according to [9], wherein the dendritic polymer is a hyperbranched polymer and / or a dendrimer;

  [11] Any one of [1] to [10], wherein the ink composition is used in an ink jet recording method in which a droplet of an ink composition is ejected and the droplet is attached to a recording medium for recording. Ink set as described;

  [12] The ink set according to [11], wherein the ink jet recording method is a recording method using an ink jet head that forms ink droplets by mechanical deformation of a piezoelectric element;

  [13] An ink jet recording method, wherein the ink set according to any one of [1] to [10] is used as an ink composition;

  [14] A recorded matter recorded by the inkjet recording method according to [13].

  According to the ink set of the present invention, the ink jet recording method using the ink set, and the recorded matter, it is possible to obtain a good image in which bleeding and color bleeding are suppressed.

  Hereinafter, preferred embodiments of the present invention will be described.

[Ink set]
As described above, the ink set of the present embodiment contains at least an ink composition A containing at least an electrolyte, a polymerizable compound, and a photopolymerization initiator, a colorant, and a polymerizable compound. Ink composition B.

  In the present embodiment, “electrolyte” refers to a substance that dissolves in a solvent such as water and ionizes to generate yin and yang ions. However, substances that are added to the recording medium such as sizing agent and affect the bleeding and bleeding of the recorded image are excluded.

  The electrolyte added to the ink composition A is an anionic polymer electrolyte, a cationic polymer electrolyte, or an amphoteric polymer electrolyte from the viewpoint of aggregation and gelation tendency in the case of aggregation due to neutralization of electrostatic repulsion. It is preferable that it is 1 type, or 2 or more types selected from the group consisting of.

  The anionic polymer electrolyte is preferably a polycarboxylic acid from the viewpoint of aggregation with cation-dispersed fine particles dispersed by a positive charge. Specific examples of the polycarboxylic acid include polyacrylic acid, polymethacrylic acid, and copolymers thereof.

  The cationic polymer electrolyte is preferably a polyamine from the viewpoint of aggregation with the anion-dispersed fine particles dispersed by a negative charge. Specific examples of the polyamine include polyallylamine, polyethyleneimine, and copolymers thereof.

  The amphoteric polymer electrolyte is preferably an amino acid from the viewpoint of aggregation with both cation-dispersed fine particles dispersed by positive charges and anion-dispersed fine particles dispersed by negative charges. Specific examples of amino acids include polyamine sulfone and polyamino acid.

  The amount of the electrolyte added is preferably 0.1 to 1% by weight.

  The polymerizable compound added to the ink composition A is preferably ethylene glycol monoallyl ether and / or N-vinyl compound from the viewpoint of storage stability. Here, the N-vinyl compound is preferably N-vinylformamide from the viewpoint of curability.

  The addition amount of the polymerizable compound is preferably 50 to 95% by weight.

  A dendritic polymer can also be used as the polymerizable compound. The dendritic polymer (dendritic polymer) is preferably a hyperbranched polymer and / or a dendrimer from the viewpoint of reducing ink viscosity.

  Here, the “hyperbranched polymer” is a tree-like multibranched polymer composed of a large number of branches, and the molecular structure is not necessarily regular. The hyperbranched polymer is preferably a hyperbranched polymer having a functional group branched with dipentaerythritol as a core. As hyperbranched polymers, STAR-501 and 502 manufactured by Osaka Organic Chemical Industry Co., Ltd. are available.

  “Dendrimer” is a dendritic multi-branched polymer consisting of a large number of branches, a compound having a regular molecular structure and having no defects, and is a commonly used linear polymer. In comparison, reactive functional groups can be densely and concentratedly arranged on the outermost surface.

  The addition amount of the dendritic polymer is preferably 1.0 to 30.0% by weight.

  Examples of the photopolymerization initiator used in the ink composition A include known photopolymerization initiators described on pages 39 to 56 of Photopolymer Handbook (published by Photographic Society Society, 1989); The compounds described in JP-A-13142 and JP-A-2-4804 can be arbitrarily used.

  The polymerization initiator used in the ink composition A is, for example, one that absorbs ultraviolet rays or visible light in the region of about 200 nm to 450 nm and generates radicals or ions to initiate polymerization of the polymerizable compound.

  Typical examples of the polymerization initiator used for the ink composition A include benzoin methyl ether, benzoin ethyl ether, isopropyl benzoin ether, isobutyl benzoin ether, 1-phenyl-1,2-propane. Dione-2- (o-ethoxycarbonyl) oxime, benzyl, diethoxyacetophenone, benzophenone, chlorothioxanthone, 2-chlorothioxanthone, isopropylthioxanthone, 2-methylthioxanthone, polychlorinated polyphenyl, hexachlorobenzene, and the like are preferable. , Isobutyl benzoin ether, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime.

  Also, Vicure 10, 30 (manufactured by Stauffer Chemical), Irgacure 184, 127, 500, 651, 2959, 907, 369, 379, 754, 1700, 1800, 1850, 1870, 819, OXE01, Darocur 1173, TPO, ITX (Manufactured by Ciba Specialty Chemicals), Quanture CTX, ITX (manufactured by Aceto Chemical), Kayacure DETX-S (manufactured by Nippon Kayaku), ESACURE KIP150 (manufactured by Lamberti), Lucirin TPO (manufactured by BASF) Available polymerization initiators can also be used.

  The addition amount of the polymerization initiator is preferably 0.5 to 15% by weight.

  The ink composition B preferably contains at least a colorant, a dispersant, a polymerizable compound, and a radical polymerization inhibitor.

  As the colorant used in the ink composition B, it is preferable to use a pigment from the viewpoint of light resistance. As the pigment, both inorganic pigments and organic pigments can be used.

  As the inorganic pigment, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black and channel black, iron oxide, titanium dioxide, alumina, calcium carbonate and the like can be used.

  Examples of the organic pigment include insoluble azo pigments, condensed azo pigments, azo lakes and chelate azo pigments, phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone. Polycyclic pigments such as pigments, dye chelates (for example, basic dye chelates, acid dye chelates, etc.), dye lakes (basic dye lakes, acid dye lakes), nitro pigments, nitroso pigments, aniline black, Examples include daylight fluorescent pigments. The above pigments can be used alone or in combination of two or more. Further, any pigment that is not described in the color index can be used as long as it is insoluble in the ink composition.

  As the black pigment, carbon black is preferable. Specific examples of carbon black include # 2300, # 900, HCF88, # 33, # 40, # 45, # 52, MA7, MA8, MA100, # 2200B manufactured by Mitsubishi Chemical, Raven 5750, 5250 , 5000, 3500, 1255, 700, etc., Regal 400R, 330R, 660R, Mogu L, 700, Monarch 800, 880, 900, 1000, 1100, 1300, manufactured by Cabot Corporation , 1400, etc., Color Black FW1, FW2V, FW18, FW200, Color Black S150, S160, S170, Printex 35, U, V, 140U, Special Black 6, 5 4A, same Etc. can be mentioned, may be used as these one or a mixture of.

  Examples of yellow pigments include C.I. I. Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 120, 128, 129, 138, 150, 151, 154, 155, 180, 185, etc., preferably C.I. I. 1 or a mixture of two or more selected from the group consisting of CI Pigment Yellow 74, 109, 110, 128 and 138.

  Examples of magenta and light magenta pigments include C.I. I. Pigment Red, 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 15: 1, 112, 122, 123, 168, 184, 202, 209 and C.I. I. Pigment violet 19 and the like, preferably C.I. I, Pigment Red 122, 202, 209 and C.I. I. One or a mixture of two or more selected from the group consisting of CI Pigment Violet 19.

  Examples of cyan and light cyan pigments include C.I. I. Pigment blue 1, 2, 3, 15: 3, 15: 4, 15:34, 16, 22, 60 and C.I. I. Bat blue 4, 60 and the like, preferably C.I. I. Pigment Blue 15: 3, 15: 4, and one or a mixture of two or more selected from the group consisting of 60.

  As pigments used in white ink, titanium dioxide, calcium carbonate, calcium sulfate, zinc oxide, barium sulfate, barium carbonate, silica, alumina, kaolin, clay, talc, clay, aluminum hydroxide, magnesium carbonate, white hollow resin emulsion Preferably, it is one or a mixture of two or more selected from the group consisting of these.

  The pigment that can be used for the metallic ink is not particularly limited. For example, the composite pigment base material having a structure in which a release resin layer and a metal or metal compound layer are sequentially laminated on a sheet-like base material surface is used. Examples thereof include those that are peeled off and pulverized from the sheet-like substrate with the interface between the metal or metal compound layer and the peeling resin layer as a boundary.

  The metal or metal compound used in the metal or metal compound layer of the composite pigment base for producing the metal foil piece is not particularly limited as long as it has a function such as having a metallic luster. Aluminum, silver, gold, nickel, chromium, tin, zinc, indium, titanium, copper and the like are used, and at least one of these simple metals, metal compounds, alloys thereof and mixtures thereof is used. In addition, the pigments of the respective colors can be mixed and used in order to adjust the color tone.

  In addition, the pigments of the respective colors can be mixed and used in order to adjust the color tone. For example, pigment black 7 and pigment blue 15: 3 can be mixed for the purpose of changing the color tone of reddish black to blue.

  The pigment used in the ink composition B preferably has an average particle size in the range of 10 to 500 nm, more preferably about 50 to 300 nm. Further, the blending amount of the pigment used in the present embodiment may be appropriately determined according to the type of the ink composition such as the dark and light ink composition, but is preferably 1.5 to 20% by weight in the ink composition. Is 3 to 10% by weight.

  The metallic pigment is preferably a metal foil piece having an average thickness of 30 nm or more and 100 nm or less, a 50% volume average particle diameter of 1.0 μm or more and 4.0 μm or less, and a maximum particle diameter in the particle size distribution of 12 μm or less.

Examples of the dispersant used in the ink composition B include, for example, polyoxyalkylene polyalkylene polyamine (C ₂ H ₄ N) _n — (PO) _x — (EO) _y —OH (where n, x And y each represents an integer of 1 or more, PO means propylene oxide, and EO means ethylene oxide). Specific examples of polyoxyalkylene polyalkylene polyamines include, for example, Discole N-503, N-506, N-509, N-512, N-515, N-518, N-520 and the like. Can do.

  The amount of the dispersant added is preferably 0.1 to 20% by weight, more preferably 0.5 to 10% by weight.

  As the polymerizable compound used in the ink composition B, the polymerizable compound used in the ink composition A can be used.

  Examples of the radical polymerization inhibitor used in the pigment dispersion include, for example, phenolic antioxidants, hindered amine light stabilizers, phosphorus antioxidants, hydroquinone monomethyl ether widely used for (meth) acrylic monomers, and hydroquinone. , T-butylcatechol, pyrogallol and the like.

  The addition amount of the radical polymerization inhibitor is preferably 0.001 to 0.5% by weight.

  The ink composition B may further contain, as optional components, a resin emulsion, an inorganic oxide colloid, a wetting agent, a pH adjusting agent, a preservative, a fungicide, a surfactant, and the like. As the surfactant, one or more selected from BYK-347,348, UV3500, UV3570 (manufactured by BYK Japan) and Surfinol E1010 (manufactured by Nissin Chemical) from the viewpoint of improving the wettability with respect to the recording medium. It is preferable that it is a compound of these. The addition amount of the surfactant is preferably 0.01 to 5.0% by weight.

  The ink compositions A and B are preferably added with a polymerization accelerator from the viewpoint of improving curability. As a polymerization accelerator, the polymerization accelerator which consists of an amine compound can be mentioned, for example. The amine compound is not particularly limited, but an aminobenzoate derivative is particularly preferable because the problem of odor and the curing of the ink composition become more reliable. This is because the aminobenzoate derivative reduces polymerization inhibition by oxygen.

  The aminobenzoate derivative preferably has no absorption in the wavelength region of 350 nm or more. Examples of such aminobenzoate derivatives include, but are not limited to, ethyl-4-dimethylaminobenzoate, 2-ethylhexyl-4-dimethylaminobenzoate, etc., which include Darocur EDB, EHA (Ciba Specialty Chemicals) Product name).

  The addition amount of the polymerization accelerator is preferably 0.01 to 5.0% by weight.

  The ink compositions A and B are preferably added with a sensitizer from the viewpoint of improving curability. Examples of sensitizers include thioxanthone compounds.

  The addition amount of the sensitizer is preferably 0.001 to 1.0% by weight.

  Ink compositions A and B are preferably added with a radical polymerization inhibitor from the viewpoint of storage stability. As the radical polymerization inhibitor, any compound having a radical scavenging ability can be used without any problem. However, from the viewpoint of the polymerization prevention effect obtained with respect to ejection suitability and content, that is, efficiency, hydroquinones, catechol It is preferable that the compound be at least one compound selected from quinones having a condensed aromatic ring, hindered amines, phenols, phenothiazines, and condensed aromatic ring quinones.

  Specific examples of the hydroquinones include hydroquinone, hydroquinone monomethyl ether, 1-o-2,3,5-trimethylhydroquinone, 2-tert-butyl hydroquinone and the like.

  Specific examples of the catechols include catechol, 4-methylcatechol, 4-tert-butylcatechol and the like.

  Specific examples of the hindered amines include compounds having a tetramethylpiperidinyl group.

  Specific examples of the phenols include phenol, butylhydroxytoluene, butylhydroxyanisole, pyrogallol, gallic acid, gallic acid alkyl ester, and the like.

  Specific examples of the phenothiazines include phenothiazine.

  Specific examples of the condensed aromatic ring quinones include naphthoquinone and the like.

  The radical polymerization inhibitor is preferably carbon black or inorganic / organic fine particles having a polymerization-inhibiting functional group introduced on the surface from the viewpoint of the polymerization preventing effect obtained with respect to the content, that is, the efficiency. Specific examples of the polymerization-preventing functional group include a hydroxyphenyl group, a dihydroxyphenyl group, a tetramethylpiperidinyl group, and a condensed aromatic ring.

  The radical polymerization inhibitor is available under the trade name Irgastab UV10 from Ciba Specialty Chemicals.

  The addition amount of the radical polymerization inhibitor is preferably 0.001 to 1.0% by weight.

  The ink compositions A and B are preferably made of only a non-volatile material. By configuring the ink compositions A and B with only a non-volatile substance, it is possible to obtain an effect of preventing the occurrence of printing defects due to the generation of bubbles and the occurrence of tack due to bleedout. In the present invention, the “volatile substance” means a substance having a vapor pressure equal to or higher than that of water at room temperature and normal pressure, and the “nonvolatile substance” means more than water at room temperature and normal pressure. Refers to a substance with a low vapor pressure.

[Inkjet recording method]
The ink set described above is preferably used in an inkjet recording method in which recording is performed by ejecting droplets of an ink composition and attaching the droplets to a recording medium.

  The order of applying the ink composition A and the ink composition B described above to the recording medium may be any order, that is, the ink composition A is adhered to the recording medium, and then the ink composition is applied to the recording medium. Any of the method of adhering B, the method of adhering the ink composition A after printing the ink composition B, and the method of mixing the ink composition A and the ink composition B immediately before or after the injection should be suitably performed. Can do.

  In the ink jet recording method of the present embodiment, good printing can be realized by bringing the ink composition A and the ink composition B into contact with each other. The following is a hypothesis, and the reason for this is as follows, provided that the present invention is not construed as being limited.

  When the ink composition A and the ink composition B come into contact with each other, the electrolyte in the ink composition A destroys the dispersion state of the colorant, the polymerizable compound, and other components in the ink composition B, and aggregates them. Conceivable. In particular, it is considered that the electrolyte in the ink composition A reacts with the pigment as the colorant in the ink composition B to form an aggregate. These aggregates are considered to suppress the penetration and diffusion of the colorant into the recording medium.

  Further, the agglomerates remaining on the recording medium adhere to the recording medium, and are further bonded to each other to form a film, thereby facilitating the fixing of the colorant to the recording medium, and further cured by irradiation with ultraviolet rays. It is considered that the strength of the recording medium is improved and it has an effect of adhering to the recording medium. Thus, it is considered that an image with high color density, blurring, and less printing unevenness is realized.

  In addition, a color image has an advantage that non-uniform color mixing, that is, color bleeding, can be effectively prevented in a boundary area of different colors.

  The above mechanism is merely an assumption, and the present invention is not construed as being limited to this mechanism.

  In this embodiment, as described above, it is considered that the pigment as the colorant reacts with the electrolyte in the ink composition A to efficiently form an aggregate. Therefore, even if the pigment as the colorant is less likely to form an aggregate with the electrolyte, a good printed image can be realized by forming the aggregate. This means that the method of the present embodiment enables the use of a wide variety of colorants, regardless of the type of pigment that is the colorant. This is a great advantage of the present invention.

  Regarding the adhesion of the ink composition A to the recording medium, either the method of selectively depositing the ink composition A only at the position where the ink composition B is deposited or the method of depositing the ink composition A over the entire paper surface. The aspect of this may be sufficient.

  The former is economical because the consumption of the ink composition A can be minimized, but a certain degree of accuracy is required at the position where both the ink composition A and the ink composition B are attached.

  On the other hand, in the latter case, the accuracy requirement of the attachment positions of the ink composition A and the ink composition B is relaxed compared to the former, but a large amount of the ink composition A is attached to the entire paper surface. Is easy to curl.

  Therefore, which method is adopted may be determined in consideration of the combination of the ink composition B and the ink composition A. When the former method is adopted, the ink composition A can be attached by an ink jet recording method.

  Examples of the method for discharging the ink compositions A and B include the methods described below.

  As a first method, there is an electrostatic suction method, in which a strong electric field is applied between the nozzle and the acceleration electrode placed in front of the nozzle, and ink is continuously ejected from the nozzle in the form of droplets. This is a method in which a print information signal is applied to the deflection electrode while the ink droplet is flying between the deflection electrodes and recorded, or a method in which the ink droplet is ejected in response to the print information signal without being deflected.

  The second method is a method in which ink droplets are forcibly ejected by applying pressure to the ink liquid with a small pump and mechanically vibrating the nozzle with a crystal resonator or the like. The ejected ink droplet is charged simultaneously with the ejection, and a printing information signal is given to the deflection electrode and recorded while the ink droplet flies between the deflection electrodes.

  The third method is a method using a piezoelectric element (piezo element), in which a pressure and a print information signal are simultaneously applied to an ink liquid by a piezoelectric element to eject and record ink droplets.

  The fourth method is a method in which the ink liquid is rapidly expanded in volume by the action of heat energy, and the ink liquid is heated and bubbled by a microelectrode in accordance with a print information signal to eject and record ink droplets.

  Any of the above methods can be used for the ink jet recording method of this embodiment, and the ink jet cartridges of the respective methods can be filled.

  The ink jet recording method of the present embodiment and the ink jet recording apparatus for carrying out the same will be described below with reference to the drawings.

  The ink jet recording apparatus of FIG. 1 is an embodiment in which the ink composition A and the ink composition B are stored in a tank, and the ink composition A and the ink composition B are supplied to the recording head via an ink tube. That is, the recording head 1 and the ink tank 2 are communicated with each other through the ink tube 3. Here, the inside of the ink tank 2 is partitioned, and an ink composition B, and in some cases, a plurality of color ink composition rooms and an ink composition A room are provided.

  The recording head 1 is mounted on a carriage 4 and moved while being guided by a guide 9 by a timing belt 6 driven by a motor 5. On the other hand, the paper 7 as a recording medium is placed at a position facing the recording head 1 by the platen 8. In this embodiment, a cap 10 is provided. A suction pump 11 is connected to the cap 10 to perform a so-called cleaning operation. The sucked ink composition is stored in the waste ink tank 13 through the tube 12.

  An enlarged view of the nozzle surface of the recording head 1 is shown in FIG. The portion indicated by 1b is the nozzle surface of the ink composition A, and the nozzles 21 from which the ink composition A is ejected are provided in the vertical direction. On the other hand, the portion indicated by 1c is the nozzle surface of the ink composition B, and the ink composition B containing a yellow pigment, a magenta pigment, a cyan pigment, and a black pigment is ejected from the nozzles 22, 23, 24, and 25, respectively. Is done.

  Further, an ink jet recording method using the recording head shown in FIG. 2 will be described with reference to FIG. The recording head 1 moves in the direction of arrow A. During the movement, the ink composition A is ejected from the nozzle surface 1 b, and a band-shaped ink composition A adhesion region 31 is formed on the recording medium 7. Next, the recording medium 7 is transferred to the paper feed direction arrow B by a predetermined amount. Meanwhile, the recording head 1 moves in the direction opposite to the arrow A in the figure and returns to the left end position of the recording medium 7. Then, the ink composition B is printed on the ink composition A adhering area where the ink composition A has already been adhering to form the printing area 32. As described above, the order in which the ink composition A and the ink composition B are applied to the recording medium may be any order, and the ink composition A and the ink composition B may be applied immediately before the injection or Any of the methods of mixing immediately after can be suitably performed.

  Further, as shown in FIG. 4, in the recording head 1, all the nozzles can be arranged in the horizontal direction. In the figure, reference numerals 41a and 41b denote discharge nozzles for the ink composition A, and the ink composition B containing a yellow pigment, a magenta pigment, a cyan pigment, and a black pigment, respectively, from the nozzles 42, 43, 44, and 45. Is discharged. In the recording head of such a mode, printing can be performed in both the forward path and the backward path in which the recording head 1 reciprocates on the carriage, and at a higher speed than when the recording head shown in FIG. 2 is used. Printing can be expected.

  Further, some ink jet recording apparatuses perform replenishment of the ink composition B by replacing a cartridge that is an ink set. The ink set may be integrated with the recording head.

  A preferred example of an ink jet recording apparatus using such an ink set is shown in FIG. In the figure, the same members as those in the apparatus of FIG. In the embodiment of FIG. 5, the recording heads 1a and 1b are integrated with the ink sets 2a and 2b. The recording head 1a or 1b ejects the ink composition A and a plurality of types of ink compositions B each having a different pigment. The printing method may be basically the same as that of the apparatus shown in FIG. In this embodiment, the recording head 1a, the ink tank 2a, the recording head 1b, and the ink tank 2b move together on the carriage 4.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

A. Preparation of electrolyte solution Using polyallylamine PAA-05 (20% aqueous solution) and polyamine sulfone PAS-S-10 (30% aqueous solution) manufactured by Nittobo Co., Ltd. as the electrolyte, after removing moisture by freeze-drying method, ethylene glycol mono It melt | dissolved in allyl ether and used for the ink composition A mentioned later.

B. Preparation of pigment dispersion The pigment dispersion was prepared by the method shown below. As a coloring agent, C.I. I. To 15 parts of pigment black 7 (carbon black) and 5.0 parts of styrene-acrylic acid copolymer / ammonium salt (average molecular weight: Mw = 10,000) as a dispersant, ethylene glycol monoallyl ether as a monomer was added. The whole was made 100 parts and mixed and stirred to obtain a mixture. This mixture was subjected to a dispersion treatment for 6 hours together with zirconia beads (diameter 1.5 mm) using a sand mill (manufactured by Yaskawa Seisakusho). Thereafter, zirconia beads were separated with a separator to obtain a black pigment dispersion 1.

In the same manner, the pigment dispersion corresponding to each color, that is, yellow pigment dispersion 2 (CI Pigment Yellow 151; CI PY151), magenta pigment dispersion 3 (CI Pigment Violet 19; CI PV19), Cyan Pigment Dispersion 4 (C.I. Pigment Blue 15: 3; C.I.PB15: 3), White Pigment Dispersion 5 (C.I. Pigment White 6; C.I. PW6) was prepared. Table 1 shows the types of pigments and their addition amount (% by weight) and the addition amount (% by weight) of the dispersant.
C. Preparation of ink compositions A and B

  Two-component photocurable color ink compositions (ink compositions A and B) were prepared with the compositions shown in Table 1 below.

  First, an ink composition A1 was prepared by mixing and completely dissolving the monomer, photopolymerization initiator, polymerization accelerator, surfactant, radical polymerization inhibitor and the electrolyte prepared as described above.

  Next, similarly, a monomer, a photopolymerization initiator, a polymerization accelerator, a surfactant, and a radical polymerization inhibitor are mixed and completely dissolved, and while stirring the pigment dispersion 1 prepared as described above, the ink composition B1 The ink was gradually dropped into the ink solvent. After completion of dropping, the mixture was mixed and stirred at room temperature for 1 hour to obtain an ink composition B1.

  Thereafter, the ink compositions A1 and B1 were respectively filtered through a 5 μm membrane filter to obtain a desired ink composition. Ink compositions A2 and A3 and ink compositions B2 to B5 were prepared by the same method.

  As the hyperbranched polymer, “STAR-501” manufactured by Osaka Organic Chemical Industry was used. This “STAR-501” is a hyperbranched polymer in which a functional group is branched with dipentaerythritol as a core, and dipentaerythritol hexaacrylate is contained as a dilution monomer, viscosity: 210 Pa · s, number of functional groups: 20 ~ 99 (acrylic group).

  In Table 1, “NVF” means N-vinylformamide manufactured by Arakawa Chemical Industries, “AG” means ethylene glycol monoallyl ether manufactured by Nippon Emulsifier Co., Ltd., and “STAR-501” means Osaka Organic Chemistry. It means the hyperbranched polymer manufactured by Kogyo Co., Ltd., `` Irgacure 819 '' and `` Irgacure 127 '' mean the polymerization initiator made by Ciba Specialty Chemicals, `` Darocur EDB '' means the company's polymerization accelerator, `` BYK -UV3570 "means a silicone surfactant made by Big Chemie Japan," Kayacure DETX-S "means a polymerization initiator made by Nippon Kayaku, and" Irgastab UV10 "means Ciba Specialty Chemicals Means a radical polymerization inhibitor manufactured by The unit is% by weight.

[Test example]
The ink compositions A and B shown in Table 1 were combined to form an ink set. Using these ink sets, full-color image printing was performed using an ink jet printer PM-G920 manufactured by Seiko Epson Corporation.

  Specifically, the ink composition B1 in Table 1 is in the photo black row, the color inks B2 to B4 are in the corresponding color row, the ink composition A1 is in the gloss optimizer row, and the ink composition B5 is in matte black. Full color image printing was carried out under the printing conditions in which the ink compositions A1 to A3 covered the entire image area with the respective color ink droplets in corresponding positions filled in a row and at normal temperature and normal pressure. At this time, printing was performed so that the ink composition A1 landed immediately after printing the ink compositions B1 to B5. Similarly, printing was performed by replacing the ink composition A1 with A2 and A3, respectively.

The recording medium used was an A4 size OHP film (Fuji Xerox Co., Ltd., XEROX FILM <no frame>). Then, it is confirmed that a cured coating film of a full-color image can be obtained by performing printing and curing processing under curing conditions such that the integrated light amount is 12000 mJ / cm ² with the ultraviolet light source installed at the paper discharge port. Evaluation was performed visually under the evaluation conditions.

(1) Evaluation item 1: Evaluation of color blur after printing About the printed matter, the blur immediately after printing was evaluated visually according to the following criteria.
A: A good image without blur was obtained.
B: Slight bleeding occurred.

(2) Evaluation item 2: Evaluation of color bleed after printing The printed material was visually evaluated for non-uniform color mixing at the color boundary according to the following criteria.
A: A good image without color mixing was obtained.
B: Generation of color mixture was observed.

FIG. 2 is a diagram showing an ink jet recording apparatus that performs the method according to the present invention. In this embodiment, the recording head and the ink tank are independent from each other, and the ink composition A and the ink composition B are supplied to the recording head by an ink tube. Is done. FIG. 2 is an enlarged view of the nozzle surface of the recording head, where 1b is the nozzle surface of the ink composition A and 1c is the nozzle surface of the ink composition B. It is a figure explaining the inkjet recording head using the recording head of FIG. In the figure, 31 is an adhesion area of the ink composition A, and 32 is a printing area where the ink composition B is printed on the ink composition A being adhered. FIG. 9 is a diagram illustrating another aspect of the recording head, in which all the discharge nozzles are arranged in the horizontal direction. 1 is a diagram showing an ink jet recording apparatus that performs a method according to the present invention, and in this embodiment, a recording head and an ink tank are integrated. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording head 2 Ink tank 3 Ink tube 21 Ink composition A discharge nozzle 22, 23, 24, 25 Ink composition B discharge nozzle 31 Ink composition A adhesion area 32 Printing area

Claims (14)

An ink composition A containing at least an electrolyte, a polymerizable compound, and a photopolymerization initiator;
An ink composition B containing at least a colorant and a polymerizable compound;
An ink composition set comprising:   The ink set according to claim 1, wherein the ink compositions A and B are composed of only a non-volatile substance.   The ink set according to claim 1 or 2, wherein the electrolyte is selected from the group consisting of an anionic polymer electrolyte, a cationic polymer electrolyte, and an amphoteric polymer electrolyte.   The ink set according to claim 3, wherein the anionic polymer electrolyte is a polycarboxylic acid.   The ink set according to claim 3, wherein the cationic polymer electrolyte is a polyamine.   The ink set according to claim 3, wherein the amphoteric polymer electrolyte is an amino acid.   The ink set according to claim 1, wherein the polymerizable compound is ethylene glycol monoallyl ether and / or an N-vinyl compound.   The ink set according to claim 7, wherein the N-vinyl compound is N-vinylformamide.   The ink set according to claim 1, wherein the polymerizable compound is a dendritic polymer.   The ink set according to claim 9, wherein the dendritic polymer is a hyperbranched polymer and / or a dendrimer.   The ink set according to any one of claims 1 to 10, wherein the ink set is used in an ink jet recording method in which droplets of an ink composition are ejected and the droplets are attached to a recording medium for recording. .   The ink set according to claim 11, wherein the ink jet recording method is a recording method using an ink jet head that forms ink droplets by mechanical deformation of a piezoelectric element.   It is an inkjet recording method, Comprising: The ink set of any one of Claims 1-10 is used as an ink composition, The inkjet recording method characterized by the above-mentioned.   A recorded matter recorded by the ink jet recording method according to claim 13.

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