JP2004195961A - Ink jet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet recording method which is excellent in fade resistance against gas, lustrous properties, ink absorbency and blot resistance. <P>SOLUTION: An ink jet recording medium has, on a support, at least one ink absorbing layer, in which the surface layer being the ink absorbing layer located at a position farthest from the support has a gap structure which contains fine particles of an inorganic pigment and a cationic polymer. In the ink jet recording method, an aqueous pigment ink, which contains nonionic resin fine particles, an aqueous pigment, water and an organic solvent, is ejected on the ink jet recording medium to record an image. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a novel ink jet recording method, and more particularly, to an ink jet recording method excellent in gas fading resistance, glossiness, ink absorption and bleeding resistance.

  Ink-jet recording is the recording of images and characters by flying fine droplets of ink by various operating principles and attaching them to a recording sheet such as paper. Has an advantage that it is easy.

  In particular, as the image quality of printers has recently become higher and photographic quality has been reached, it is necessary to realize photographic quality on recording paper and reproduce the texture (gloss, smoothness, firmness, etc.) of silver halide photographs. Is required. Further, at present, there remains a problem regarding image storability, for example, light fastness, water fastness, moisture fastness and the like.

  In order to improve the water resistance or light resistance of the water-soluble dye ink, there is already known a method in which the water-soluble dye ink contains resin fine particles (latex) to coat a printed portion ( For example, see Patent Documents 1 to 4.)

  On the other hand, as one method of reproducing the texture of a silver halide photograph, a so-called swelling type in which a hydrophilic binder such as gelatin or polyvinyl alcohol is coated on a support as a recording paper is known. The method has drawbacks such as a low ink absorption rate, a sticky surface after printing, and an image bleeding easily due to humidity during storage. In particular, since the ink absorption speed is low, ink droplets are mixed before being absorbed, and bleeding between different colors (bleeding) and uneven color within the same color (beading) are likely to occur. It is very difficult to achieve.

  As a method for solving the above-mentioned problem, a so-called void type is becoming the mainstream in place of the swelling type, and is characterized by a high absorption rate because ink is absorbed in fine voids. However, when a gap type ink jet recording medium (hereinafter, also simply referred to as a recording medium) capable of achieving high image quality is combined with a water-soluble dye ink, image discoloration due to gas in a storage environment is a serious problem. It has become. Although the details of the mechanism of image discoloration caused by this gas have not been clarified yet, the gas in the storage environment, particularly the oxidizing gas, causes the dye that has penetrated into the void type inkjet recording medium to have a void structure. It is presumed that the discoloration of the dyes easily reaches and the discoloration of the dye molecules promotes image fading.

  As a method of preventing discoloration due to such oxidizing gas, after printing an image on a recording medium, the surface is subjected to lamination processing, or the recording medium on which the image is printed is stored in a frame capable of blocking gas. However, both methods require post-processing, complicating the processing steps, and resulting in an increase in cost due to the preparation of equipment for that purpose.

  As a means for overcoming such drawbacks, by printing a water-soluble dye ink containing resin fine particles in advance on a recording medium, the resin fine particles remain on the surface of the recording medium, and then are formed into a film. There has been proposed a method of preventing an oxidizing gas from penetrating into a recording medium by forming a blocking layer (for example, see Patent Document 5). The term “film formation” as used herein means that the resin fine particles are filled into the void structure portion of the outermost layer of the recording medium and, at the same time, the resin fine particles fuse to form a film. Further, by forming the film on the outermost layer, the surface roughness of the recording medium changes before and after the ink droplets adhere, and the recording medium is smoothed after printing.

  In the above method, when the inorganic fine particles constituting the void structure, particularly silica fine particles are used, they are present as fine particles together with the cationic binder, and contribute to compatibility between bleeding resistance and high gloss. . However, in the above configuration, the electrical properties of the fine particles contained in the ink greatly affect the film-forming properties. That is, when an ink containing anionic fine particles is printed on the surface of a recording medium having a strong cationic property, aggregation of the anionic fine particles easily occurs on the surface of the recording medium, and as a result, an uneven structure is formed, and the gloss is reduced. Results. In addition, the aggregation phenomenon affects the ink absorbency, and causes a decrease in ink absorbency.

Furthermore, when an image is recorded using a water-soluble dye ink, the formed image has a disadvantage that it easily bleeds during storage, and there is a strong demand for improvement in image storability when using a dye ink.
JP-A-55-18412 (Claims) JP-A-3-6270 (Claims) JP-A-3-160068 (Claims) JP-A-3-163175 (Claims) JP 2001-187852 A (Claims)

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an ink jet recording method using a dye ink having excellent gas fading resistance, glossiness, ink absorption, and bleeding resistance.

The above object of the present invention is achieved by the following configurations.
(Claim 1)
Ink jet recording having at least one ink-absorbing layer on a support, and a surface layer, which is the ink-absorbing layer furthest away from the support, having a void structure containing inorganic pigment fine particles and a cationic polymer. An ink jet recording method comprising discharging an aqueous dye ink containing nonionic resin fine particles, a water-soluble dye, water and an organic solvent onto a medium to record an image.
(Claim 2)
2. The ink jet recording method according to claim 1, wherein the inorganic pigment fine particles are silica.
(Claim 3)
The ink jet recording method according to claim 1, wherein a mass ratio (A: B) of the cationic polymer (A) and the inorganic pigment fine particles (B) is 1: 5 to 1:50.
(Claim 4)
The ink jet recording method according to claim 1, wherein the support is non-water-absorbing.
(Claim 5)
2. The ink jet recording method according to claim 1, wherein the average particle diameter of the nonionic resin fine particles is 10 nm or more and 200 nm or less.
(Claim 6)
The ink jet recording method according to claim 1, wherein the content of the nonionic resin fine particles in the aqueous dye ink is 0.2 to 10.0% by mass.
(Claim 7)
2. The ink jet recording method according to claim 1, wherein one of the minimum film forming temperature (MFT) and the glass transition temperature (Tg) of the nonionic resin fine particles is 60 ° C. or less.
(Claim 8)
2. The ink jet recording method according to claim 1, wherein the nonionic resin fine particles contain resin fine particles produced by forcibly emulsion-polymerizing a monomer using a nonionic dispersant.
(Claim 9)
2. The ink jet recording method according to claim 1, wherein the nonionic resin fine particles contain resin fine particles generated by imparting a hydrophilic group or a hydrophilic segment to a monomer, self-emulsifying and polymerizing the monomer. .

  ADVANTAGE OF THE INVENTION According to this invention, the inkjet recording method excellent in gas fading resistance, glossiness, ink absorption, and bleeding resistance can be provided.

  Hereinafter, the best mode for carrying out the present invention will be described in detail, but the present invention is not limited thereto.

  The present inventors have conducted intensive studies in view of the above problem, and as a result, have at least one ink absorbing layer on a support, and a surface layer that is an ink absorbing layer located farthest from the support is used. By recording an image by discharging an aqueous dye ink containing nonionic resin fine particles, a water-soluble dye, water and an organic solvent onto an inkjet recording medium having a void structure containing inorganic pigment fine particles and a cationic polymer, It has been found that an inkjet recording method using a dye ink having excellent gas fading resistance, glossiness and bleeding resistance can be realized, and the present invention has been reached.

  That is, a water-soluble dye ink previously containing nonionic resin fine particles is printed on a recording medium having a void-type surface layer containing inorganic fine particles and a cationic polymer for the purpose of preventing bleeding. By performing stable film formation using the conductive resin fine particles, an image having excellent gas fading resistance, glossiness, ink absorbency, and bleeding resistance can be formed.

  If the nonionic resin fine particles are present not on the ink but on the surface of the recording medium so as to exert an effect on gas discoloration resistance, the ink absorbency is extremely reduced, and the ink overflows, making it almost impractical. Conversely, if nonionic resin fine particles are present on the surface of the recording medium so that the ink absorbency is sufficient, the effect on gas discoloration resistance does not reach a practically sufficient level. In the present invention, by adding the nonionic resin fine particles to the ink, it is possible to achieve both gas fading resistance and ink absorption.

  According to the configuration of the present invention, a gas barrier layer is formed by forming a film with the nonionic resin fine particles in the ink on the surface layer, and discoloration of the dye due to an oxidizing gas or the like is prevented. The degree is improved, and the gloss is also improved.

  Hereinafter, details of the present invention will be described.

  First, the ink jet recording medium according to the present invention will be described.

  The ink jet recording medium according to the present invention has at least one ink absorbing layer on a support, and the surface layer, which is the ink absorbing layer farthest from the support, is composed of inorganic pigment fine particles and cationic polymer. Is one of the features of the present invention.

  In the present invention, the void structure refers to a structure formed mainly by soft aggregation of a binder and inorganic fine particles. The porosity of the surface layer is preferably 30 to 70%.

  The porosity in the present invention refers to the void volume relative to the solid content volume, and can be determined by the following equation.

Porosity = 100 × [(total dry film thickness−coated solid film thickness) / (total dry film thickness)]
Also, the porosity of the entire ink absorbing layer or the surface layer can be measured by the following method. For example, it can be easily obtained by coating the entire ink absorbing layer or only the surface layer on 100 μm polyethylene terephthalate and measuring the saturated transition amount by Bristow measurement or the water absorption amount.

  Various methods for forming an ink absorbing layer having a void structure (hereinafter, also referred to as a void type ink absorbing layer or a void layer) are known. For example, a uniform coating solution containing two or more polymers is coated on a support. A method of forming a void by separating these polymers from each other in a drying process, applying a coating liquid containing solid fine particles and a hydrophilic or hydrophobic binder on a support, drying the ink, and then drying the ink. A method of dissolving solid fine particles by immersing the compound in water or a liquid containing an appropriate organic solvent to form voids, applying a coating liquid containing a compound having a property of foaming during film formation, and then drying the compound in a drying process Foaming to form voids in the film, a coating solution containing porous solid fine particles and a hydrophilic binder is coated on a support, and in the porous fine particles and between the fine particles. A method of forming a gap, a coating solution containing solid fine particles and / or fine oil droplets and a hydrophilic binder having a volume of approximately equal to or more than the hydrophilic binder is coated on a support, and a gap is formed between the solid fine particles. Are known.

  As the ink absorbing layer having a void structure, a layer obtained by mixing and coating inorganic fine particles and a hydrophilic binder is preferable, and a layer having a gloss is particularly preferable.

  Examples of the inorganic pigment fine particles that can be used in the surface layer according to the present invention include, for example, light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, and hydroxide. Zinc, zinc sulfide, zinc carbonate, hydrotalcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone, zeolite, magnesium hydroxide, etc. Examples thereof include white inorganic pigments.

  The average particle diameter of the inorganic pigment fine particles is preferably 200 nm or less, particularly preferably 100 nm or less from the viewpoint of glossiness and color density. The lower limit of the average particle size is not particularly limited, but is preferably 10 nm or more from the viewpoint of production of the inorganic pigment fine particles.

  The average particle size of the inorganic pigment fine particles is determined by observing the particles themselves or the particles that appear on the cross section or surface of the ink absorbing layer with an electron microscope, calculating the particle size of 100 arbitrary particles, and calculating the simple average value (number average). Is required. Here, the particle size of each particle is represented by a diameter assuming a circle equal to its projected area.

  The inorganic pigment fine particles may be present in the ink absorbing layer in the form of primary particles or secondary particles or higher aggregated particles, but the average particle size is porous when observed with an electron microscope. Refers to the particle size of what forms independent particles in the porous layer.

  When the inorganic pigment fine particles are secondary or more agglomerated particles, the average primary particle diameter thereof is not more than the average particle diameter observed in the porous film, and the primary particle diameter of the inorganic pigment fine particles is 50 nm or less. Are preferred, more preferably 30 nm or less, most preferably 4 to 20 nm.

  As the inorganic pigment fine particles, it is preferable to use solid fine particles selected from silica and alumina or alumina hydrate, and silica is more preferable.

  As the silica, amorphous silica or colloidal silica can be used, and silica synthesized by an ordinary wet method, colloidal silica or silica synthesized by a gas phase method is preferably used, and particularly preferably used in the present invention. The obtained fine particle silica is colloidal silica or fine particle silica synthesized by a gas phase method. Among them, fine particle silica synthesized by a gas phase method has a high porosity. The alumina or alumina hydrate may be crystalline or amorphous, and may have any shape such as irregular particles, spherical particles, and acicular particles.

  As the most preferably used silica synthesized by a gas phase method having an average primary particle size of 4 to 20 nm, for example, Aerosil manufactured by Nippon Aerosil Co., Ltd. is commercially available. The vapor-phase-process fine-particle silica can be relatively easily dispersed into primary particles by suction-dispersing in water using, for example, a jet stream inductor mixer manufactured by Mitamura Riken Kogyo KK.

  Next, the cationic polymer will be described.

  The cationic polymer used for the surface layer according to the present invention is not particularly limited, and includes a cationic polymer conventionally known in inkjet recording paper. For example, “Inkjet printer technology and materials”, page 268 (published by CMC Corporation, 1998) Year) and polymers described in JP-A-9-193532, etc., and among them, a cationic polymer having a quaternary ammonium base is preferable. For example, cationic polymers having a guanidyl group described in JP-A-57-64591, dimethyldiallylammonium chloride described in JP-A-59-20696, polyamine sulfones described in JP-A-59-33176, No. 63-115780, quaternary ammonium (meth) acrylate or quaternary ammonium (meth) acrylamidoalkyl cationic polymers described in JP-A-64-9776 and JP-A-64-75281. Copolymers of dimethylallylammonium chloride and acrylamide, cationic polymers containing two or more quaternary nitrogen atoms in the repeating unit described in JP-A-3-133686, and cationic polymers described in JP-A-4-288283. Polyvinylpyrrolidone with quaternary ammonium base JP-A-6-922010 and JP-A-6-234268, cationic polymers obtained by reacting a secondary amine with epihalohydrin, polystyrene-type cationic polymers described in WO 99-64248, JP-A-11- And cationic polymers comprising a repeating unit having two or more cationic groups described in 348409.

  The cationic polymer particularly preferred in the present invention is a cationic polymer having a quaternary ammonium base, and a cationic polymer having a quaternary ammonium base in the side chain is more preferred, and particularly preferred is the following general formula (1) Is a cationic polymer having a repeating unit represented by the following formula:

In the general formula (1), R represents a hydrogen atom or an alkyl group, R ₁ , R ₂ , and R ₃ each represent an alkyl group or a benzyl group, and J represents a simple bond or a divalent organic group. X ^- represents an anionic group.

In the general formula (1), the alkyl group represented by R is preferably a methyl group. The alkyl group represented by R ₁ , R ₂ and R ₃ is preferably a methyl group, an ethyl group or a benzyl group. The divalent organic group represented by J preferably represents -CON (R ')-. R 'represents a hydrogen atom or an alkyl group.

  Examples of the anion group represented by X include a halogen ion, an acetate ion, a methyl sulfate ion, and a p-toluenesulfonic acid salt.

  The preferred cationic polymer may be a homopolymer composed of the repeating unit represented by the general formula (1), or may be a copolymer with another copolymerizable monomer. Examples of the copolymerizable repeating unit include a cationic monomer other than the general formula (1) and a monomer having no cationic group.

  Examples of the monomer having a cationic group include the following repeating units.

  As the copolymerizable repeating unit having no cationic group, for example, ethylene, styrene, butadiene, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, octyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, Octyl acrylate, hydroxylethyl methacrylate, acrylamide, vinyl acetate, vinyl methyl ether, vinyl chloride, 4-vinylpyridine, N-vinylpyrrolidone, N-vinylimidazole, acrylonitrile and the like can be mentioned.

  When the cationic polymer preferably used in the present invention has a repeating unit represented by the general formula (1), the repeating unit represented by the general formula (1) is preferably at least 20 mol%, particularly preferably. Is 40 to 100 mol%.

  Specific examples of the cationic polymer having a repeating unit represented by the general formula (1) according to the present invention are shown below, but the present invention is not limited thereto.

  The average molecular weight of the cationic polymer is generally 3000 to 200,000, preferably 5000 to 100,000. The average molecular weight is represented by a value in terms of polyethylene glycol obtained by gel permeation chromatography.

  The ratio of the inorganic pigment fine particles to the cationic polymer in the surface layer may vary depending on the type and average particle size of the fine particles or the type and weight average molecular weight of the cationic polymer.In the present invention, the ratio is such that the surface of the fine particles is cationic. In order to replace and stabilize, the mass ratio (A: B) of the cationic polymer (A) and the inorganic pigment fine particles (B) is preferably from 1: 5 to 1:50.

The amount of the cationic polymer according to the present invention to be used is generally 0.1 to 10 g, preferably 0.2 to 5 g, per 1 m ^{2 of} recording paper.

  The surface layer according to the present invention may appropriately contain a water-soluble binder in addition to the above configuration.

  Examples of the water-soluble binder include polyvinyl alcohol, gelatin, polyethylene oxide, polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, polyurethane, dextran, dextrin, carrageenan (κ, ι, λ, etc.), agar, pullulan, and water-soluble polyvinyl butyral , Hydroxyethylcellulose, carboxymethylcellulose and the like. Two or more of these water-soluble resins can be used in combination.

  The water-soluble resin preferably used in the present invention is polyvinyl alcohol. The polyvinyl alcohol preferably used in the present invention includes, in addition to ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, modified polyvinyl such as polyvinyl alcohol having a cation-modified terminal or an anion-modified polyvinyl alcohol having an anionic group. Also includes alcohol.

  The polyvinyl alcohol obtained by hydrolyzing vinyl acetate preferably has an average degree of polymerization of 1,000 or more, and particularly preferably has an average degree of polymerization of 1,500 to 5,000. The saponification degree is preferably from 70 to 100%, particularly preferably from 80 to 99.5%.

  As the cation-modified polyvinyl alcohol, for example, as described in JP-A-61-10483, a primary to tertiary amino group or quaternary ammonium group is contained in the main chain or side chain of the polyvinyl alcohol. Which is obtained by saponifying a copolymer of an ethylenically unsaturated monomer having a cationic group and vinyl acetate.

  Examples of the ethylenically unsaturated monomer having a cationic group include trimethyl- (2-acrylamido-2,2-dimethylethyl) ammonium chloride and trimethyl- (3-acrylamido-3,3-dimethylpropyl) ammonium chloride N-vinylimidazole, N-vinyl-2-methylimidazole, N- (3-dimethylaminopropyl) methacrylamide, hydroxylethyltrimethylammonium chloride, trimethyl- (2-methacrylamidopropyl) ammonium chloride, N- (1, 1-dimethyl-3-dimethylaminopropyl) acrylamide and the like.

  The ratio of the cation-modified group-containing monomer in the cation-modified polyvinyl alcohol is 0.1 to 10 mol%, preferably 0.2 to 5 mol%, based on vinyl acetate.

  The anion-modified polyvinyl alcohol is, for example, a polyvinyl alcohol having an anionic group as described in JP-A-1-206088, and described in JP-A-61-237681 and JP-A-63-307979. Copolymers of such vinyl alcohol with a vinyl compound having a water-soluble group, and modified polyvinyl alcohol having a water-soluble group as described in JP-A-7-285265.

  Examples of the nonion-modified polyvinyl alcohol include, for example, a polyvinyl alcohol derivative in which a polyalkylene oxide group is added to a part of vinyl alcohol as described in JP-A-7-9758, and JP-A-8-25795. A block copolymer of the described vinyl compound having a hydrophobic group and vinyl alcohol may, for example, be mentioned.

  Polyvinyl alcohol may be used in combination of two or more kinds such as different degrees of polymerization and types of modification.

  The thickness of the surface layer according to the present invention is preferably 3 to 15 μm.

  As a method for measuring the thickness of the surface layer, a method in which a cross section of the recording medium provided with the surface layer is accurately cut in a vertical direction, and then observed using an optical microscope or a scanning electron microscope can be mentioned.

The addition amount of the inorganic fine particles used in the surface layer, the ink absorbing capacity required, porosity, type of inorganic fine particles depends largely on the type of the water-soluble resin, typically an ink jet recording medium 1 m ^2, per, 5 30 g, preferably 10 to 25 g.

  In the inkjet recording medium according to the present invention, it is preferable to provide an ink absorbing layer for absorbing the ink solvent between the support and the surface layer.

  The ink absorption layer provided between the support and the surface layer is roughly classified into a swelling type and a void type.

  As the swelling type, a hydrophilic binder, for example, gelatin, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, or the like, which is applied alone or in combination, and which is used as an ink absorbing layer can be used.

  The void type is obtained by mixing and applying fine particles and a hydrophilic binder, and is particularly preferably glossy. As the fine particles, alumina or silica is preferable, and particularly, silica using silica having a particle size of 0.1 μm or less is preferable. As the hydrophilic binder, for example, those using gelatin, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide or the like alone or in combination are preferable.

  In order to provide suitability for continuous or high-speed printing, it is suitable for the recording medium to have a high ink absorption rate. In this regard, the void type can be particularly preferably used.

  As the inorganic fine particles used for the above purpose, the same inorganic fine particles as those used in the above-mentioned surface layer can be used.

  Examples of the hydrophilic binder include the same compounds as the water-soluble binder described in the above-mentioned surface layer.

The amount of the inorganic fine particles used in the ink absorbing layer provided between the support and the surface layer greatly depends on the required ink absorption capacity, the porosity of the void layer, the type of the inorganic fine particles, and the type of the water-soluble resin. In general, the amount is usually 5 to 30 g, preferably 10 to 25 g, per m ² of the ink jet recording medium.

  The ratio of the inorganic fine particles to the water-soluble resin used in the ink absorbing layer provided between the support and the surface layer is usually from 2: 1 to 20: 1 by mass, and especially from 3: 1 to 10: 1. Preferably, there is.

The ink absorbing layer provided between the support and the surface layer may contain the same cationic polymer as used in the surface layer, and is usually 0.1 to 10 g, preferably 0.2 to 10 g per m ^{2 of} the inkjet recording medium. Used in the range of 5 g.

In the void layer of the ink absorbing layer provided between the support and the surface layer, the total amount of voids (void volume) is preferably 20 ml or more per 1 m ² of the recording medium. By setting the void volume to 20 ml / m ² or more, even if the amount of ink at the time of printing increases, the ink absorbency can be improved, the image quality can be improved, and high drying property can be achieved.

  As another type of the void type of the ink absorbing layer provided between the support and the surface layer, besides forming an ink solvent absorbing layer using inorganic fine particles, a polyurethane resin emulsion and a water-soluble epoxy compound and / or acetoacetylated The ink solvent absorbing layer may be formed by using a coating liquid in which polyvinyl alcohol is used in combination with an epichlorohydrin polyamide resin. In this case, the polyurethane resin emulsion is preferably a polyurethane resin emulsion having a polycarbonate chain, a polycarbonate chain and a polyester chain and having a particle size of 3.0 μm, and the polyurethane resin of the polyurethane resin emulsion is a polyol having a polycarbonate polyol, a polycarbonate polyol and a polyester polyol. And a polyurethane resin obtained by reacting the compound with an aliphatic isocyanate compound having a sulfonic acid group in the molecule, and further having an epichlorohydrin polyamide resin and a water-soluble epoxy compound and / or acetoacetylated vinyl alcohol. preferable.

  It is presumed that weak aggregation of cations and anions is formed in the ink solvent absorbing layer using the above polyurethane resin, and accordingly, voids having an ink solvent absorbing ability are formed, so that an image can be formed.

  In the present invention, the average porosity of the entire ink absorbing layer of the ink jet recording medium is preferably 40 to 70%.

  Next, the support used in the ink jet recording medium according to the present invention will be described.

  As the support used in the present invention, a support conventionally used for an ink jet recording medium, for example, a paper support such as plain paper, art paper, coated paper and cast coated paper, a plastic support, and polyolefin on both sides. Although a coated paper support and a composite support obtained by laminating these can be used, it is preferable to use a non-water-absorbing support from the viewpoint of further exhibiting the effects of the present invention.

  Examples of the non-water-absorbing support used in the present invention include a plastic resin film support and a support in which both surfaces of paper are covered with a plastic resin film. Examples of the plastic resin film support include a polyester film, a polyvinyl chloride film, a polypropylene film, a cellulose triacetate film, a polystyrene film, and a laminated film support thereof. These plastic resin films may be transparent or translucent.

  In the present invention, a particularly preferred support is a support in which both sides of paper are coated with a plastic resin, and a most preferred support is a support in which both sides of paper are coated with a polyolefin resin.

  Hereinafter, a support in which both surfaces of a paper, which is a particularly preferred support in the present invention, are coated with a polyolefin resin will be described.

  The paper used for the support according to the present invention is made from wood pulp as a main raw material, and if necessary, in addition to wood pulp, using synthetic pulp such as polypropylene or synthetic fiber such as nylon or polyester. As the wood pulp, any of LBKP, LBSP, NBKP, NBSP, LDP, NDP, LUKP, and NUKP can be used, but it is preferable to use LBKP, NBSP, LBSP, NDP, and LDP which contain a large amount of short fibers. However, the ratio of LBSP and / or LDP is preferably 10 to 70%. As the pulp, chemical pulp (sulfate pulp or sulfite pulp) having a small amount of impurities is preferably used, and pulp having improved whiteness by performing a bleaching treatment is also useful.

  In paper, for example, higher fatty acids, sizing agents such as alkyl ketene dimer, white pigments such as calcium carbonate, talc, titanium oxide, paper strength enhancers such as starch, polyacrylamide, polyvinyl alcohol, fluorescent whitening agents, polyethylene A water retention agent such as glycols, a dispersant, a softening agent such as quaternary ammonium, and the like can be appropriately added.

  The freeness of the pulp used for papermaking is preferably 200 to 500 ml according to the CSF specification, and the sum of the 24 mesh residue and the 42 mesh residue whose fiber length after beating is specified in JIS P 8207 is 30 to 50. 70% is preferred. In addition, it is preferable that the 4 mesh residue is 20% or less.

  The basis weight of the paper is preferably from 50 to 250 g, and particularly preferably from 70 to 200 g. The thickness of the paper is preferably 50 to 210 μm.

The paper can also be calendered at the papermaking stage or after papermaking to provide high smoothness. The paper density is generally 0.7 to 1.2 g / cm ³ (JIS P 8118). Further, the rigidity of the base paper is preferably from 20 to 200 g under the conditions specified in JIS P 8143.

  A surface sizing agent may be applied to the paper surface, and the same sizing agent as can be added to the base paper can be used as the surface sizing agent.

  The pH of the paper is preferably 5 to 9 when measured by the hot water extraction method specified in JIS P 8113.

  Next, the polyolefin resin covering both sides of the paper will be described.

  Examples of the polyolefin resin used for this purpose include polyethylene, polypropylene, polyisobutylene, and polyethylene. Polyolefins such as a copolymer mainly composed of propylene are preferable, and polyethylene is particularly preferable.

  Hereinafter, particularly preferred polyethylene will be described.

  The polyethylene that covers the front and back surfaces of the paper is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but other LLDPE, polypropylene, and the like can also be partially used.

  In particular, the polyolefin layer on the coating layer side preferably has improved opacity and whiteness by adding rutile or anatase type titanium oxide therein. The titanium oxide content is generally 1 to 20%, preferably 2 to 15%, based on the polyolefin.

  In the polyolefin layer, a color pigment having high heat resistance and a fluorescent whitening agent for adjusting the white background can be added.

  Examples of the coloring pigment include ultramarine, navy blue, cobalt blue, phthalocyanine blue, manganese blue, cerulean, tungsten blue, molybdenum blue, anthraquinone blue, and the like.

  Examples of the fluorescent whitening agent include dialkylaminocoumarin, bisdimethylaminostilbene, bismethylaminostilbene, 4-alkoxy-1,8-naphthalenedicarboxylic acid-N-alkylimide, bisbenzoxazolylethylene, and dialkylstilbene. Is mentioned.

  The amount of polyethylene used on the front and back of the paper is selected so as to optimize the thickness of the ink absorbing layer and the curl in low and high humidity after providing the back layer. Is 15 to 50 μm on the ink absorbing layer side and 10 to 40 μm on the back layer side. The ratio of the front and back polyethylene is preferably set so as to adjust the curl that changes depending on the type and thickness of the ink absorbing layer, the thickness of the inner paper, and the like. It is approximately 3/1 to 1/3.

  Further, the paper support coated with the polyethylene preferably has the following properties (1) to (7).

  (1) The tensile strength is preferably 19.6 to 294 N in the vertical direction and 9.8 to 196 N in the horizontal direction at the strength specified by JIS P 8113.

  (2) The tear strength is preferably 0.20 to 2.94 N in the longitudinal direction and 0.098 to 2.45 N in the horizontal direction, as defined by JIS P 8116.

(3) The compression modulus is preferably 9.8 kN / cm ² .

  (4) The opacity is preferably 80% or more, particularly preferably 85 to 98%, as measured by the method specified in JIS P 8138.

(5) As for whiteness, L ^* , a ^* and b ^* defined by JIS Z 8727 may be L ^* = 80 to 96, a ^* = − 3 to +5, and b ^* = − 7 to +2. preferable.

(6) Clark stiffness, the support Clark stiffness in the conveying direction of the recording medium is 50~300cm ^3/100 is preferred.

  (7) The moisture in the base paper is preferably 4 to 10% based on the middle paper.

  (8) The glossiness (75-degree specular glossiness) on the surface on which the ink absorbing layer is provided is preferably 10 to 90%.

  Next, the aqueous dye ink according to the present invention will be described.

  The aqueous dye ink according to the present invention is characterized by containing at least nonionic resin fine particles, a water-soluble dye, water and an organic solvent.

  First, the nonionic resin fine particles according to the present invention will be described. In the present invention, the nonionic resin fine particles include nonionic resin fine particles.

  The polymer constituting the nonionic resin fine particles that can be used in the present invention is not particularly limited. For example, an acrylic resin (for example, an acrylic resin, an acrylic-styrene copolymer, an acrylic-vinyl acetate copolymer, Acrylic-silicon copolymer, etc.), urethane resin, polyester resin, vinyl acetate resin (for example, vinyl acetate resin, vinyl acetate-ethylene copolymer, etc.), butadiene resin (for example, styrene-butadiene copolymer, acrylic) Examples thereof include a nitrile-butadiene copolymer), a fluorine-based resin, and a polyamide-based resin. Usually, these resin fine particles are obtained by an emulsion polymerization method. As the surfactant, polymerization initiator and the like used therefor, those used in a conventional manner may be used. Regarding the method for synthesizing resin fine particles, U.S. Pat. Nos. 2,852,368, 2,853,457, 3,411,911, 3,411,912, 4,197,127, Belgian Patent Nos. 688,882, 691,360, 712,823, JP-B-45-5331, JP-A-60-18540, JP-A-5130217, JP-A-58-137831, and 55- No. 50240 and the like.

  Further, the nonionic resin fine particles according to the present invention can be easily obtained as a commercial product. For example, Superflex 500 and 550 manufactured by Daiichi Kogyo Seiyaku Co., Ltd. and Bondick 1040N and 1050B manufactured by Dainippon Ink and Chemicals, Inc. -NS, 1230 NS, 1250, 1310 NSA, 1610 NS, 1670 NS, 1850 NS, 1910, 1980 NS, 2210, 2220, WLI-601, WLI-602, ES-850, ES-801, Sumika Flex S-305 manufactured by Sumitomo Chemical Co., Ltd. S-400, S-400HQ, S-410, S-450, S-460, S-7400, S-480, S-700, S-751, S-830, S-950, S-960, Takeda Pharmaceutical Bamboo rack W-512A6, W-635, XW-74-X08N, manufactured by Kogyo Co., Ltd. Made in Ebafanoru AP-6, AP-12, AP-24, APC-55, APC-66, whereas it is possible to mention the company Yushi of ULS-700, ULS-1700 or the like.

  A preferred method for synthesizing the nonionic resin fine particles is an emulsion polymerization method. The nonionic resin fine particles include resin fine particles obtained by forcibly emulsifying a monomer using a nonionic dispersant as an emulsifier (hereinafter, also referred to as a forced emulsification type), and a resin having a hydrophilic group or a hydrophilic group. Resin fine particles (hereinafter also referred to as a self-emulsifying type) obtained by imparting an acidic segment and self-emulsifying a monomer are preferred. Examples of nonionic dispersants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, nonionic surfactants of polyoxyethylene / polyoxypropylene block polymers, polyethylene glycol, polyvinyl alcohol, and polyvinyl. And hydrophilic binders such as pyrrolidone and hydroxymethylcellulose. The self-emulsifying type is preferable to the forced emulsifying type because it does not contain a surfactant and can suppress bleed out of the surfactant.

  In the present invention, the average particle size of the nonionic resin fine particles is preferably from 10 nm to 200 nm, more preferably from 50 to 150 nm.

  The average particle size of the nonionic resin fine particles can be easily determined using a commercially available particle size measuring device using a light scattering method or a laser Doppler method, for example, Zetasizer 1000 (manufactured by Malvern).

  Further, in the water-soluble dye ink according to the present invention, the content of the nonionic resin fine particles in the ink is preferably 0.2 to 10% by mass, more preferably 0.5 to 5% by mass. is there. When the addition amount of the nonionic resin fine particles is 0.2% by mass or more, a more sufficient effect on gas discoloration can be exerted. When the addition amount is 10% by mass or less, the ink ejection property becomes more stable. This is more preferable because the increase in ink viscosity during storage can be suppressed.

  When the water-soluble dye ink contains anionic resin fine particles, the mass ratio of the anionic resin fine particles to the nonionic resin fine particles is preferably 1: 1 or less, more preferably 2: 1. It is as follows.

  Further, in the present invention, it is preferable that either the minimum film forming temperature (MFT) or the glass transition temperature (Tg) of the nonionic resin fine particles be 60 ° C. or less. In the present invention, a film-forming auxiliary may be added to control the minimum film-forming temperature of the nonionic resin fine particles. The film forming aid is an organic compound (usually an organic solvent) which is also called a plasticizer and lowers the minimum film forming temperature of the polymer latex. )"It is described in.

  The water-soluble dye ink according to the present invention contains at least a water-soluble dye, water, and an organic solvent in addition to the nonionic resin fine particles described above.

  Examples of the water-soluble dye that can be used in the present invention include, for example, an azo dye, a methine dye, an azomethine dye, a xanthene dye, a quinone dye, a phthalocyanine dye, a triphenylmethane dye, a diphenylmethane dye, and the like. The compounds are shown below. However, the compounds are not limited to these exemplified compounds.

[C. I. Acid Yellow)
1, 3, 11, 17, 18, 19, 23, 25, 36, 38, 40, 42, 44, 49, 59, 61, 65, 67, 72, 73, 79, 99, 104, 110, 114, 116, 118, 121, 127, 129, 135, 137, 141, 143, 151, 155, 158, 159, 169, 176, 184, 193, 200, 204, 207, 215, 219, 220, 230, 232, 235, 241, 242, 246
[C. I. Acid orange)
3, 7, 8, 10, 19, 24, 51, 56, 67, 74, 80, 86, 87, 88, 89, 94, 95, 107, 108, 116, 122, 127, 140, 142, 144, 149, 152, 156, 162, 166, 168
[C. I. Acid Red)
1, 6, 8, 9, 13, 18, 27, 35, 37, 52, 54, 57, 73, 82, 88, 97, 106, 111, 114, 118, 119, 127, 131, 138, 143, 145, 151, 183, 195, 198, 211, 215, 217, 225, 226, 249, 251, 254, 256, 257, 260, 261, 265, 266, 274, 276, 277, 289, 296, 299, 315, 318, 336, 337, 357, 359, 361, 362, 364, 366, 399, 407, 415
[C. I. Acid Violet)
17, 19, 21, 42, 43, 47, 48, 49, 54, 66, 78, 90, 97, 102, 109, 126
[C. I. Acid Blue)
1, 7, 9, 15, 23, 25, 40, 62, 72, 74, 80, 83, 90, 92, 103, 104, 112, 113, 114, 120, 127, 128, 129, 138, 140, 142, 156, 158, 171, 182, 185, 193, 199, 201, 203, 204, 205, 207, 209, 220, 221 224, 225, 229, 230, 239, 249, 258, 260, 264, 278, 279, 280, 284, 290, 296, 298, 300, 317, 324, 333, 335, 338, 342, 350
[C. I. Acid Green)
9, 12, 16, 19, 20, 25, 27, 28, 40, 43, 56, 73, 81, 84, 104, 108, 109
[C. I. Acid Brown)
2, 4, 13, 14, 19, 28, 44, 123, 224, 226, 227, 248, 282, 283, 289, 294, 297, 298, 301, 355, 357, 413
[C. I. Acid Black)
1, 2, 3, 24, 26, 31, 50, 52, 58, 60, 63, 107, 109, 112, 119, 132, 140, 155, 172, 187, 188, 194, 207, 222
[C. I. Direct yellow)
8, 9, 10, 11, 12, 22, 27, 28, 39, 44, 50, 58, 86, 87, 98, 105, 106, 130, 132, 137, 142, 147, 153
[C. I. Direct orange)
6, 26, 27, 34, 39, 40, 46, 102, 105, 107, 118
[C. I. Direct red)
2, 4, 9, 23, 24, 31, 54, 62, 69, 79, 80, 81, 83, 84, 89, 95, 212, 224, 225, 226, 227, 239, 242, 243, 254
[C. I. (Direct violet)
9, 35, 51, 66, 94, 95
[C. I. Direct blue)
1, 15, 71, 76, 77, 78, 80, 86, 87, 90, 98, 106, 108, 160, 168, 189, 192, 193, 199, 200, 201, 202, 203, 218, 225, 229,237,244,248,251,270,273,274,290,291
[C. I. Direct green)
26, 28, 59, 80, 85
[C. I. Direct brown)
44, 106, 115, 195, 209, 210, 222, 223
[C. I. Direct black)
17, 19, 22, 32, 51, 62, 108, 112, 113, 117, 118, 132, 146, 154, 159, 169
[C. I. Basic Yellow)
1, 2, 11, 13, 15, 19, 21, 28, 29, 32, 36, 40, 41, 45, 51, 63, 67, 70, 73, 91
[C. I. (Basic orange)
2, 21, 22
[C. I. (Basic Red)
1, 2, 12, 13, 14, 15, 18, 23, 24, 27, 29, 35, 36, 39, 46, 51, 52, 69, 70, 73, 82, 109
[C. I. (Basic violet)
1, 3, 7, 10, 11, 15, 16, 21, 27, 39
[C. I. (Basic blue)
1, 3, 7, 9, 21, 22, 26, 41, 45, 47, 52, 54, 65, 69, 75, 77, 92, 100, 105, 117, 124, 129, 147, 151
[C. I. Basic green)
1,4
[C. I. (Basic Brown)
1
[C. I. Reactive Yellow)
2, 3, 7, 15, 17, 18, 22, 23, 24, 25, 27, 37, 39, 42, 57, 69, 76, 81, 84, 85, 86, 87, 92, 95, 102, 105, 111, 125, 135, 136, 137, 142, 143, 145, 151, 160, 161, 165, 167, 168, 175, 176
[C. I. (Reactive orange)
1, 4, 5, 7, 11, 12, 13, 15, 16, 20, 30, 35, 56, 64, 67, 69, 70, 72, 74, 82, 84, 86, 87, 91, 92, 93, 95, 107
[C. I. Reactive Red)
2, 3, 5, 8, 11, 21, 22, 23, 24, 28, 29, 31, 33, 35, 43, 45, 49, 55, 56, 58, 65, 66, 78, 83, 84, 106, 111, 112, 113, 114, 116, 120, 123, 124, 128, 130, 136, 141, 147, 158, 159, 171, 174, 180, 183, 184, 187, 190, 193, 194, 195, 198, 218, 220, 222, 223, 228, 235
[C. I. (Reactive violet)
1, 2, 4, 5, 6, 22, 23, 33, 36, 38
[C. I. Reactive Blue)
2, 3, 4, 5, 7, 13, 14, 15, 19, 21, 25, 27, 28, 29, 38, 39, 41, 49, 50, 52, 63, 69, 71, 72, 77, 79, 89, 104, 109, 112, 113, 114, 116, 119, 120, 122, 137, 140, 143, 147, 160, 161, 162, 163, 168, 171, 176, 182, 184, 191, 194, 195, 198, 203, 204, 207, 209, 211, 214, 220, 221, 222, 231, 235, 236
[C. I. Reactive green)
8, 12, 15, 19, 21
[C. I. Reactive Brown)
2, 7, 9, 10, 11, 17, 18, 19, 21, 23, 31, 37, 43, 46
[C. I. Reactive Black)
5, 8, 13, 14, 31, 34, 39
The dyes listed above are described in "Dyeing Notebook 21st Edition" (published by Shisensensha) and the like.

  Of these water-soluble dyes, phthalocyanine dyes are preferred.

  Examples of the phthalocyanine dye include unsubstituted dyes and dyes having a central element, and examples of the central element include metal and non-metallic dyes, preferably copper, and more preferably C.I. I. Direct Blue 199.

  The organic solvent that can be used in the present invention is not particularly limited, but is preferably a water-soluble organic solvent. Specifically, alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, Tertiary butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol, etc., polyhydric alcohols (eg, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexane) Diol, pentanediol, glycerin, hexanetriol, thiodiglycol, etc.), polyhydric alcohol ethers (for example, ethylene glycol Monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl Ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, triethylene glycol dimethyl ether, dipropylene glycol monopropyl ether, tripropylene glycol dimethyl Ethers), amines (eg, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethylene) Imines, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc.), amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.), heterocycles (eg, 2-pyrrolidone, N-methyl- 2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, etc., sulfoxides (for example, dimethyl sulfoxide) And the like, sulfones (eg, sulfolane), sulfonates (eg, 1-butanesulfonic acid sodium salt), urea, acetonitrile, acetone and the like.

  Various surfactants can be used in the water-soluble dye ink according to the present invention. The surfactants that can be used in the present invention are not particularly limited. For example, dialkyl sulfosuccinates, alkyl naphthalene sulfonates, anionic surfactants such as fatty acid salts, polyoxyethylene alkyl ethers, and polyoxyethylene alkyl ethers Examples include nonionic surfactants such as oxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene block copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. In particular, an anionic surfactant and a nonionic surfactant can be preferably used.

  In the ink of the present invention, a polymer surfactant can also be used. For example, styrene-acrylic acid-alkyl acrylate copolymer, styrene-acrylic acid copolymer, styrene-maleic acid-acrylic acid Alkyl ester copolymer, styrene-maleic acid copolymer, styrene-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-methacrylic acid copolymer, styrene-maleic acid half ester copolymer, vinylnaphthalene-acrylic acid Copolymers and vinyl naphthalene-maleic acid copolymers can be exemplified.

  In the water-soluble dye ink according to the present invention, in addition to the above description, if necessary, the emission stability, the compatibility with the print head or ink cartridge, the storage stability, the image storability, and other objectives for improving various performances In addition, various additives known in the art, for example, a viscosity modifier, a specific resistance modifier, a film forming agent, an ultraviolet absorber, an antioxidant, an anti-fading agent, a deodorant, and a rust inhibitor may be appropriately selected and used. For example, liquid paraffin, dioctyl phthalate, tricresyl phosphate, oil droplets fine particles such as silicone oil, and the ultraviolet absorber described in JP-A-57-74193, JP-A-57-87988 and JP-A-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-3-13376. Discoloration inhibitors described in JP-A-59-42993, JP-A-59-52689, JP-A-62-280069, JP-A-61-242871 and JP-A-4-219266. Agents and the like.

  The ink jet head used in the ink jet recording method of the present invention may be of an on-demand type or a continuous type. As the discharge method, an electro-mechanical conversion method (for example, a single cavity type, a double cavity type, a bender type, a piston type, a shared mode type, a shared wall type, etc.) and an electro-thermal conversion method (for example, thermal inkjet) Type, bubble jet (R) type, etc.), electrostatic suction type (eg, electric field control type, slit jet type, etc.), and discharge type (eg, spark jet type, etc.). Alternatively, any of the ejection methods may be used.

  Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.

Example 1
<< Preparation of recording medium >>
[Preparation of recording medium 1]
(Preparation of silica dispersion D1)
25% by mass of fumed silica (Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.) having primary particles having an average particle diameter of about 0.012 μm, which is uniformly dispersed in advance, and a water-soluble optical brightener UVITENFFW LIQUID (Ciba Specialty) 400 L of a silica dispersion B1 (pH = 2.3, containing 1% by mass of ethanol) containing 0.3% by mass of Chemicals Co., Ltd.), 12% of a cationic polymer (PA) and 10% of n-propanol % And ethanol of 2% were added to 110 L of an aqueous solution C1 (pH = 2.5, containing 2 g of an antifoaming agent SN381 manufactured by Sannobuco) at room temperature with stirring at 3000 rpm. Next, 54 L of a mixed aqueous solution A1 of boric acid and borax at a 1: 1 mass ratio (each having a concentration of 3% by mass) was gradually added with stirring.

Then, the mixture was dispersed with a high-pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd. at a pressure of 3 kN / cm ² , and the whole amount was finished to 630 L with pure water to obtain a substantially transparent silica dispersion D1.

  The silica dispersion D1 was filtered using a TCP-30 type filter manufactured by Advantech Toyo having a filtration accuracy of 30 μm.

(Preparation of silica dispersion D2)
400 L of the silica dispersion B1 was added to 120 L of an aqueous solution C2 (pH = 2.5) containing 12% by mass of the cationic polymer (P-2), 10% by mass of n-propanol, and 2% by mass of ethanol at room temperature. While stirring at 3000 rpm, and then 52 L of the mixed aqueous solution A1 was gradually added while stirring.

Then, the mixture was dispersed at a pressure of ³ kN / cm ² with a high-pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd., and the whole amount was finished to 630 L with pure water to obtain a substantially transparent silica dispersion D2.

  The silica dispersion D2 was filtered using a TCP-30 type filter manufactured by Advantech Toyo having a filtration accuracy of 30 μm.

(Preparation of oil dispersion)
20 kg of diisodecyl phthalate and 20 kg of an antioxidant (AO-1) are dissolved by heating in 45 kg of ethyl acetate, and a gelatin aqueous solution containing 8 kg of acid-treated gelatin, 2.9 kg of cationic polymer P-1 and 10.5 kg of saponin After mixing with 210 L at 55 ° C. and emulsifying and dispersing with a high-pressure homogenizer, the whole amount was finished to 300 L with pure water to prepare an oil dispersion.

(Preparation of coating liquid)
Using the dispersions prepared above, the following additives were sequentially mixed to prepare a coating solution. In addition, each addition amount was represented by the amount per 1 L of the coating solution.

<First layer coating solution: Lowermost layer>
580 ml of silica dispersion D1
10% aqueous solution of polyvinyl alcohol (Kuraray: PVA203)
5ml
Polyvinyl alcohol (average degree of polymerization: 3800, saponification degree 88%)
290 ml of 6.5% aqueous solution
30ml oil dispersion
42 ml of latex dispersion (AE803, manufactured by Showa Polymer)
8.5 ml of ethanol
Finished to 1000ml with pure water <Coating solution for 2nd layer>
Silica dispersion D1 600ml
10% aqueous solution of polyvinyl alcohol (Kuraray: PVA203)
5ml
Polyvinyl alcohol (average degree of polymerization: 3800, saponification degree 88%)
270 ml of 6.5% aqueous solution
20ml oil dispersion
Latex dispersion (Showa Polymer: AE803) 22ml
8 ml of ethanol
Finished to 1000ml with pure water <Coating solution for 3rd layer>
630 ml of silica dispersion D2
10% aqueous solution of polyvinyl alcohol (Kuraray: PVA203)
5ml
Polyvinyl alcohol (average degree of polymerization: 3800, saponification degree 88%)
270 ml of 6.5% aqueous solution
Oil dispersion 10ml
Latex dispersion (AE803, manufactured by Showa Polymer Co., Ltd.) 5 ml
3 ml of ethanol
The total volume was made up to 1000 ml with pure water. <Coating solution for fourth layer: surface layer>
660 ml of silica dispersion D2
10% aqueous solution of polyvinyl alcohol (Kuraray: PVA203)
5ml
Polyvinyl alcohol (average degree of polymerization: 3800, saponification degree 88%)
250% 6.5% aqueous solution
3% 4% aqueous solution of betaine surfactant-1
2 ml of a 25% aqueous solution of saponin
3 ml of ethanol
The total amount was made up to 1000 ml with pure water. The mass ratio of the cationic polymer (P-2) and the inorganic pigment fine particles (Aerosil 200) in the fourth layer was 1: 6.9.

  Each coating solution prepared as described above was filtered through a TCPD-30 filter manufactured by Advantech Toyo Co., Ltd. having a filtration accuracy of 20 μm, and then filtered through a TCPD-10 filter.

(Application)
Next, four layers of the above coating solutions were simultaneously coated on a paper support 1 coated on both sides with polyethylene at 40 ° C. using a slide hopper type coater so as to have a wet film thickness described below.

<Wet film thickness>
First layer: 42 μm
Second layer: 39 μm
Third layer: 44 μm
4th layer: 38 μm
The paper support 1 used above had a water content of 8% and a basis weight of 170 g, and the surface of the photographic base paper was extruded with a polyethylene containing 6% of anatase type titanium oxide to a thickness of 35 μm and melt-coated. Polyethylene having a thickness of 40 μm was extruded and melt-coated on the back surface. After a corona discharge was applied to the front side, a subbing layer was coated with polyvinyl alcohol (PVA235 manufactured by Kuraray Co., Ltd.) so as to be 0.05 g per 1 m ² of the recording medium. A back layer containing about 0.4 g of a styrene / acrylate latex binder at 80 ° C., 0.1 g of an antistatic agent (cationic polymer) and 0.1 g of about 2 μm silica as a matting agent was applied.

  The drying after the application of the coating liquid for the ink absorbing layer was performed by lowering the film surface temperature to 13 ° C. by passing through a cooling zone maintained at 5 ° C. for 15 seconds, and then forming a plurality of drying zones. After the temperature was appropriately set and drying was carried out, the recording medium 1 was obtained by winding in a roll.

  The cross section of the obtained recording medium 1 was observed with an electron microscope, and the average particle diameter of the silica fine particles was measured to be 23 nm.

[Preparation of recording medium 2]
In the production of the recording medium 1, a recording medium 2 was prepared in the same manner except that the cationic polymer (P-2) used in the fourth layer (surface layer) was replaced with the same amount of the cationic polymer (P-8). Was prepared.

  The cross section of the obtained recording medium 2 was observed with an electron microscope, and the average particle diameter of the silica fine particles was measured to be 22 nm.

[Preparation of recording medium 3]
In the production of the recording medium 1, the same amount of vapor-phase alumina (trade name: aluminum oxide C, manufactured by Degussa Co., Ltd., primary) was used instead of the inorganic pigment fine particles (vapor-phase silica) used in the fourth layer (surface layer). A recording medium 3 was produced in the same manner except that an average particle size of 13 nm was used.

  The cross section of the obtained recording medium 3 was observed with an electron microscope, and the average particle size of the alumina fine particles was measured to be 31 nm.

[Preparation of recording medium 4]
In the production of the recording medium 1, the same procedure was performed except that the ratio of the cationic polymer (P-2) used in the fourth layer (surface layer) to the inorganic pigment fine particles (fumed silica) was changed to 1: 4.0. Thus, a recording medium 4 was produced.

[Preparation of Recording Medium 5]
A recording medium 5 was produced in the same manner as in the production of the recording medium 1 except that the paper support 1 was replaced by a paper support 2 produced by the following method.

(Preparation of paper support 2)
70 parts by mass of hardwood kraft pulp (LBKP) beaten to a Canadian standard freeness of 330 ml, 25 parts by mass of hardwood bleached sulfite pulp (LBSP) beaten to a Canadian standard freeness of 280 ml, and a Canadian standard freeness of 280 ml Five parts by mass of beaten softwood kraft pulp (NBKP) were mixed, and the number of revolutions of the double disc refiner was changed to obtain a pulp having a mass average fiber length of 1.20 mm. 2.0 parts of cationized starch, 0.4 part of alkyl ketene dimer resin as a sizing agent, 0.1 part of anionic polyacrylamide resin, 0.1 part of polyamide polyamine epichlorhydrin resin 0.7 per 100 parts of beaten pulp. Was added and the pH was adjusted to 7.5 with caustic soda, and a paper support 2 having a basis weight of 170 g and a thickness of 160 μm was prepared using a fourdrinier paper machine.

[Preparation of Recording Medium 6]
A recording medium 6 was produced in the same manner as in the production of the recording medium 1 except that the cationic polymer (P-2) used in the fourth layer (surface layer) was omitted.

<< Preparation of aqueous dye ink >>
[Preparation of dye ink 1]
C. I. Direct Blue 199 3% by mass
Diethylene glycol 25% by mass
Sodium dioctyl sulfosuccinate 0.01% by mass
The total amount was adjusted to 100% by mass with water to prepare Dye Ink 1.

[Preparation of dye inks 2 to 7]
Dye inks 2 to 7 were prepared in the same manner except that the resin fine particles shown in Table 1 were added to Dye Ink 1 so as to have the contents shown in Table 1.

  The details of the resin fine particles used for preparing the dye inks 2 to 7 are as follows.

NLxA: Nonionic resin fine particles (urethane resin Superflex 500 MFT = 5 ° C, average particle size = 140 nm, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
NLxB: Nonionic resin fine particles (acrylic resin Movinyl 730 MFT = 0 ° C, average particle size = 120 nm, manufactured by Clariant)
NLxC: Nonionic resin fine particles (acrylic resin Nippol Lx816 Tg = -10 ° C. Average particle size = 140 nm, manufactured by Zeon Corporation)
NLxD: Nonionic resin fine particles (urethane resin Superflex E-4000 MFT = 5 ° C, average particle size = 280 nm, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
NLxE: Nonionic resin fine particles (urethane resin Takerac W-635 MFT = 71 ° C., average particle size = 150 nm, manufactured by Takeda Pharmaceutical Company Limited)
ALx1: anionic resin fine particles (urethane resin fine particles Superflex 130 MFT = 55 ° C. average particle size = 42 nm manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
The average particle diameter of each resin fine particle was measured using a laser Doppler system Zetasizer 1000 (manufactured by Malvern).

<< Inkjet image formation >>
Using MJ800C manufactured by Seiko Epson as a printer, the dye inks 1 to 7 prepared above were respectively loaded into ink cartridges equipped in the printer, and the ejection amount was determined in combination with each recording medium shown in Table 1. a solid image such that 10 ml / m ² as, linewidth is (dpi referred to in the present invention, the number of dots per 2.54 cm) 720 dpi printing cyan fine line one pixel in the image 1 12 was output.

<< Inkjet image measurement and evaluation >>
With respect to the cyan image formed as described above, each measurement and evaluation were performed according to the following methods.

(Evaluation of gas fading resistance)
After each solid image was exposed to an environment having an ozone concentration of 50 ppm at 23 ° C. for 120 minutes, the reflection density before and after the exposure was measured with a monochromatic red light of an optical densitometer (X-Rite 938 manufactured by X-Rite), The image remaining rate was determined according to the following equation, and the gas fading resistance was evaluated according to the following criteria.

Image residual rate = density after exposure / density before exposure × 100 (%)
5: Image residual ratio is 95% or more 4: Image residual ratio is 85 to less than 95% 3: Image residual ratio is 70 to less than 85% 2: Image residual ratio is less than 60 to 70% 1: Image residual ratio is 60% Less than (evaluation of glossiness)
The solid image prepared above was measured for image clarity (gloss value C value%) at a reflection of 60 degrees and an optical comb of 2 mm with an image clarity measuring device ICM-1DP (manufactured by Suga Test Machine Co., Ltd.). The evaluation was performed according to the following criteria.

4: C value% is 71 or more 3: C value% is 70 to 56
2: C value% is 55 to 41
1: C value% is 40 or less In the above-mentioned evaluation ranks, 4 and 3 were judged to be practically particularly preferable ranks.

(Evaluation of bleeding resistance)
The evaluation of the bleeding resistance was performed by storing the thin line image prepared above in a thermo-hygrostat at 60 ° C. and 80% RH for 7 days, and comparing it with an image of the same configuration stored at room temperature and normal humidity. The change of the thin line before and after was visually evaluated by 20 general evaluators, and determined according to the following criteria.

：: 16 or more people evaluated that they did not change before and after storage. ：: 12 to 15 people evaluated that they did not change before and after storage. Δ: 8 people evaluated that they did not change before and after storage. ~ 11 people ×: 7 or less people who did not change before and after storage (evaluation of ink absorbency)
A cyan solid image was produced in the same manner as described above in combination with each of the recording media and inks shown in Table 1 at an ink ejection amount of 20 ml / m ^2, and the uniformity of the solid portion (the presence or absence of a mottled pattern) was observed. Visual observation was performed while changing the distance, and the ink absorbency was evaluated according to the following criteria.

5: A completely uniform solid image 4: An observation distance of 20 cm or more gives a uniform feeling 3: An observation distance of 40 cm or more gives a uniform feeling 2: An observation distance of 60 cm or more gives a uniform feeling 1: An observation distance A mottled pattern is felt even at 60 cm or more. Table 2 shows the results obtained.

  As is clear from Table 2, the recording medium was formed using an aqueous dye ink containing inorganic pigment fine particles and a cationic polymer in the surface layer, nonionic resin fine particles, a water-soluble dye, water and an organic solvent. The image of the invention was found to be less susceptible to discoloration due to gas in a storage environment than the comparative image, and was excellent in glossiness and bleeding resistance. By making the ratio of the polymer and the inorganic fine particles a specific range, or by using a non-water-absorbing support as a support, it can be seen that the effects of the present invention are further exhibited, and as a dye ink, It can be seen that the effects of the present invention are further exhibited by using nonionic resin fine particles having an average particle size or MFT or Tg.

Example 2
Similarly to the method described in Example 1, the yellow ink (Y), the magenta ink (M), and the black ink (K) were used instead of the dye inks 1 to 7 as the cyan ink (C). After printing an image with the above configuration, the same evaluation was performed. As a result, the same result as the cyan ink of Example 1 could be obtained with any of the inks.

Example 3
Four color inks of Y, M, C, K prepared in Examples 1 and 2 and light color four color inks (Ly, Lm, Lc) in which the amount of water-soluble dye added to each ink was adjusted to 1/4 , Lk) were loaded into an inkjet printer (IGUAZU 1044SD manufactured by Konica Corporation) and an image was printed on the recording medium 1 prepared in Example 1. As a result, gas fading resistance, glossiness, and bleeding were observed. A good image having excellent resistance and ink absorption was obtained.

Claims (9)

Ink jet recording having at least one ink-absorbing layer on a support, and a surface layer, which is the ink-absorbing layer furthest away from the support, having a void structure containing inorganic pigment fine particles and a cationic polymer. An ink jet recording method comprising discharging an aqueous dye ink containing nonionic resin fine particles, a water-soluble dye, water and an organic solvent onto a medium to record an image. 2. The ink jet recording method according to claim 1, wherein the inorganic pigment fine particles are silica. The ink jet recording method according to claim 1, wherein a mass ratio (A: B) of the cationic polymer (A) and the inorganic pigment fine particles (B) is 1: 5 to 1:50. The ink jet recording method according to claim 1, wherein the support is non-water-absorbing. 2. The ink jet recording method according to claim 1, wherein the average particle diameter of the nonionic resin fine particles is 10 nm or more and 200 nm or less. The ink jet recording method according to claim 1, wherein the content of the nonionic resin fine particles in the aqueous dye ink is 0.2 to 10.0% by mass. 2. The ink jet recording method according to claim 1, wherein one of the minimum film forming temperature (MFT) and the glass transition temperature (Tg) of the nonionic resin fine particles is 60 ° C. or less. 2. The ink jet recording method according to claim 1, wherein the nonionic resin fine particles contain resin fine particles produced by forcibly emulsion-polymerizing a monomer using a nonionic dispersant. 2. The ink jet recording method according to claim 1, wherein the nonionic resin fine particles contain resin fine particles produced by imparting a hydrophilic group or a hydrophilic segment to a monomer, self-emulsifying and polymerizing the monomer. .