JP2005161859A - Inkjet recording method and recorded matter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording method and a recorded matter excellent in gloss feeling, smoothness and texture. <P>SOLUTION: In the inkjet recording method, in which a dispersed ink for each color prepared by dispersing a pigment in a solvent to obtain a mean dispersion diameter in each color of 0.05 to 0.2 μm is adhered onto a recording medium including fine particles of a mean particle diameter of 0.003 to 0.1 μm and a hydrophilic binder, having a weight ratio of 2.5 to 12 of the fine particles to the hydrophilic binder, and having a center-line mean surface roughness Ra value A of 0.21 to 0.46 μm, when an image recording part having a reflection density of 1.0 by each single color is prepared, each color ink, wherein the image recording part for each color has a center-line mean surface roughness Ra value B of 0.7 Ra value A to 1.8 Ra value A, is used to perform recording. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ink jet recording method used for forming an ink jet image and a recorded matter thereof.

  In recent years, with the widespread use of digital cameras or computers, hard copy image recording technology for recording these images on paper has been rapidly developed. The ultimate goal of these hard copies is to bring the image quality closer to that of a silver halide photograph. In particular, the color reproducibility, color density, texture, resolution, glossiness, light resistance, etc. should be closer to that of a silver halide photograph. It is a development goal.

  As such hard copy recording methods, various recording methods such as sublimation type thermal transfer method, ink jet method, electrostatic recording method, etc. are proposed in addition to direct photographing of a display displaying an image with a silver salt photograph. Has been put to practical use. Among these recording methods, ink jet printers have the advantage of being easy to achieve full color and having less printing noise, and have been rapidly spreading in recent years.

  The ink jet recording method is capable of recording high-definition images with a relatively simple apparatus, and has been rapidly developed in various fields. In addition, there are various uses, and a recording medium or ink suitable for each purpose is used.

  The recording medium used in the ink jet recording method is such that the ink-receiving layer is a support itself such as paper such as plain paper, or an ink absorption layer on a support that also serves as an absorber such as coated paper. Or an ink-absorbing layer coated on a non-absorbing support such as a resin-coated paper or a polyester film. Among them, the recording medium of the type in which an ink absorbing layer is coated on a non-absorbing support is a silver salt such as gloss, gloss, and depth because the support has a high surface smoothness and little swell. It is preferably used for an output that requires a high quality texture such as a photograph. Furthermore, as a glossy recording medium having high gloss and gloss, a swelling type recording medium in which a water-soluble binder such as polyvinyl pyrrolidone or polyvinyl alcohol is coated as an ink absorbing layer on a non-absorbent support, A so-called void-type recording medium is used in which a fine void structure is formed with a pigment or a pigment and a binder as the ink absorption layer, and the ink is absorbed into the void.

  On the other hand, inks are roughly classified into dye inks in which a color material is dissolved in a solvent and dispersed inks in which a color material is dispersed in a solvent. Since the dye ink is dissolved in a solvent, it tends to have good color developability and high chroma and is preferably used for outputting silver salt photographic images and the like. However, dye inks are basically prone to light fading, and when posting for a certain period of time, such as signboards and posters, there is a problem that if the surface is not laminated, it will fade immediately. It was. On the other hand, the dispersed ink generally does not easily cause light fading and is preferably used for producing a poster or the like. In the past, dispersed inks had a large dispersed particle size, mainly from the viewpoint of ensuring dispersion stability, and were completely unsuitable for silver salt photographic-like printing. The grain size was reduced, and silver salt photographic printing was also performed. Here, for example, an organic pigment, an inorganic pigment, and colored fine particles are used as the color material of the dispersed ink.

  In recent years, high-definition ink-jet recording has progressed, and printing that requires a high quality silver-salt photograph is often performed. When performing printing that requires such a high texture, glossy recording media such as the above-described swelling type recording media and void type recording media are preferably used.

  When recording dye ink, the entire ink penetrates into the ink absorbing layer, so the surface of the medium after recording is almost unchanged from before recording, and there is a sense of incongruity at the boundary between the non-image area and the recording area. There wasn't much. On the other hand, when the dispersed ink is recorded on the glossy recording medium, even if the ink absorption layer has no holes as in the swelling type recording medium or the holes have a hole as in the void type recording medium, the diameter of the ink is not increased. In comparison, since the particle size of the color material is larger, most of the dispersed color material cannot enter the ink absorbing layer and is exposed on the surface of the recording medium. As a result, in the dispersed ink recording portion, a new surface is formed by the dispersed color material exposed on the medium surface. Therefore, the smoothness of the surface changes from the original medium surface depending on the accumulated state of the exposed coloring material. This change in smoothness appears as a change in glossiness, and the gloss is different between the recorded portion of the image and the non-image portion. If there is a difference in gloss within one recording medium, it will be felt very uncomfortable, and will be perceived as being far from the homogeneity of silver halide photography. In particular, the conventional dispersed ink has a drawback that the surface smoothness tends to be considerably rough from the original recording medium surface due to the color material deposited on the surface of the recording medium, the glossiness is also low, and an image with a strong sense of incongruity tends to be formed. Had.

  As a method for eliminating such a sense of incongruity, there are known a method of performing a laminating process after image recording and a method of pressing with a heat roll after image formation. It has disadvantages such as large energy consumption and the necessity of a laminate material and a dedicated recording medium.

  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 and a recorded matter that are excellent in gloss, smoothness, and texture without post-processing.

  The above object of the present invention has been achieved by the following constitution.

  (Claim 1) It contains fine particles having an average particle diameter of 0.003 μm to 0.1 μm and a hydrophilic binder, the weight ratio of the fine particles to the hydrophilic binder is 2.5 to 12, and the center line average surface roughness A dispersed ink of each color in which a pigment is dispersed in a solvent so as to have an average dispersion diameter of 0.05 to 0.2 μm for each color is adhered onto a recording medium having a Ra value A of 0.21 to 0.46 μm. In the ink jet recording method, when an image recording portion having a reflection density of 1.0 for each color is created, the center line average surface roughness Ra value B of the image recording portion for each color is 0.7 Ra value A An ink jet recording method comprising: recording using each color ink having a value of ~ 1.8Ra.

  (Claim 2) The inkjet recording method according to claim 1, wherein the dispersed ink contains at least a pigment, a water-soluble organic solvent, and water.

  (Claim 3) The inkjet recording method according to claim 1, wherein a weight ratio of the fine particles to the hydrophilic binder is 3 to 10.

  (Claim 4) It contains fine particles having an average particle size of 0.003 μm to 0.1 μm and a hydrophilic binder, the weight ratio of the fine particles to the hydrophilic binder is 2.5 to 12, and the center line average surface roughness A dispersed ink of each color in which a pigment is dispersed in a solvent so as to have an average dispersion diameter of 0.05 to 0.2 μm for each color is adhered onto a recording medium having a Ra value A of 0.21 to 0.46 μm. When an image recording portion having a reflection density of 1.0 for each color, which is a recorded matter recorded by the ink jet recording method, is created, the center line average surface roughness Ra value of the image recording portion for each color A recorded matter in which B is recorded using ink of each color having a 0.7 Ra value A to 1.8 Ra value A.

  (Claim 5) The recorded matter according to claim 4, wherein the dispersed ink contains at least a pigment, a water-soluble organic solvent, and water.

  (Claim 6) The recorded matter according to claim 4, wherein a weight ratio of the fine particles to the hydrophilic binder is 3 to 10.

  According to the present invention, it is possible to provide an ink jet recording method and a recorded matter excellent in glossiness, smoothness and texture.

  In view of the above problems, the present inventors have conducted intensive studies on the glossiness and texture of the formed inkjet output image. As a result, the relationship between the center line average roughness Ra (μm) of the image portion, etc. By setting the range, it is possible to remarkably improve the inhomogeneity due to the difference in texture between the image area and the non-image area, which is likely to occur when printing with pigment ink, and to obtain smoothness and texture like silver halide photography. I found.

  Attempts have been made to match the glossiness of the image and non-image areas, but the printed portion with pigment ink has a metallic luster and the difference in glossiness from the non-image areas is greater. It is in. However, when the glossiness between the image portion and the non-image portion is approximated, the texture of the image portion is remarkably deteriorated, and rather a non-uniform feeling is caused. The present inventors have found that the relationship between the center line average surface roughness Ra value and the like of the image portion correlates with the texture, and as soon as the present invention has been achieved.

  Details of the present invention will be described below.

  In the present invention, the center line average surface roughness Ra value A (hereinafter abbreviated as Ra value A) of the non-image portion of the recording medium and the center line average surface roughness Ra value B (hereinafter referred to as Ra value B) of the image recording portion. The abbreviation is expressed as described in the claims.

  The centerline average surface roughness Ra as used in the present invention is defined by the following JIS surface roughness (B0601), and is the centerline average surface roughness measured with a reference length of 5.0 mm and a cutoff value of 0.8 mm. Represent.

  The centerline average roughness (Ra) is a portion of the measured length L in the direction of the centerline from the roughness curve, the centerline of this extracted portion is the X axis, the direction of the vertical magnification is the Y axis, and the roughness When the curve is represented by Y = f (X), the value obtained by the following equation is represented by micrometers (μm).

  As a measuring method of the centerline average surface roughness (Ra), the humidity is adjusted for 24 hours in a 25 ° C., 65% RH environment where the measurement samples are not overlapped with each other, and then the measurement is performed in the same environment. The conditions that are not superposed here are, for example, a method of winding up with the edge portion of the inkjet recording medium raised, a method of stacking paper between each recording medium, a frame made of cardboard, etc. One of the methods to fix. An example of a measuring apparatus that can be used is Surfcom 500B manufactured by Tokyo Seimitsu Co., Ltd.

  The present invention is characterized in that the relationship between the Ra value A of the non-image portion of the recording medium and the Ra value B of the image recording portion is 0.7 ≦ Ra value B / Ra value A ≦ 1.8. Preferably, 0.8 ≦ Ra value B / Ra value A ≦ 1.6, and particularly preferably 0.9 ≦ Ra value B / Ra value A ≦ 1.4.

  Conventionally, the ratio B / A between the Ra value A of the non-image portion and the Ra value B of the image recording portion in the recording medium on which the pigment ink is recorded has been less than 0.7 or greater than 1.8. When the value of B / A is less than 0.7, reflection such as metallic luster occurs in the image recording portion, and the image recording portion is lifted up and felt very uncomfortable. On the other hand, when the value of B / A exceeds 1.8, the smoothness of the image recording portion is poorer than that of the non-image portion, and the connection between the non-image portion and the image recording portion is not smooth, and only the image recording portion. The image is far from the homogeneity of silver halide photography.

  The image recording portion of the recording medium referred to in the present invention refers to a region where dispersed ink images are formed on the recording medium by output. There is no particular limitation on the density of the formed image.

  From the viewpoint of further exerting the effect of the present invention, the black density is preferably 0.5 to 1.5 and the relationship represented by the formula (1).

Formula (1)
0.7 ≦ Ra value B / Ra value A ≦ 1.8
Furthermore, in the black density of 0.8 to 1.2, the relationship represented by the formula (1) is preferable. In addition, when the formed image is a yellow, magenta or cyan image, it is preferable that the formation density of each is 0.1 to 2.0 and the relationship represented by the formula (1). In the concentration range of 0.5 to 1.5, the relationship represented by the formula (1) is preferable.

  In the above, the specific method for achieving the specified conditions is not particularly limited. For example, the solvent absorption rate of the recording medium can be adjusted by optimizing the type or amount of the water-soluble binder and adjusting the degree of crosslinking of the binder. In addition, in the dispersed ink, the primary particle size and the secondary particle size of the colorant particles are optimized, the dynamic surface tension of the ink is adjusted by optimizing the type and amount of the surfactant and the water-soluble solvent, and in the ink. By controlling the structure taken by the colorant particles in the image recording part by appropriately combining the colorant concentration, the dispersant type or amount used, and the dispersion particle stabilization technology by optimizing the ink composition The Ra value of the image recording portion that is optimal for the Ra value of the recording medium to be used can be obtained.

  In achieving the object of the present invention, the average height difference h between the non-image portion of the recording medium and the surface of the single dot is characterized by 2.0 μm or less. Preferably, the average height difference h is 1. It is 5 micrometers or less, More preferably, it is 0.1-1.0 micrometer.

  There is no particular limitation on the method for obtaining the average height difference between the non-image portion and the surface of the single dot. For example, using a scanning electron microscope, the highest density portion between the non-image portion and the image recording portion of the recording medium is used. Taking a tomographic image of the image, and calculating the average height difference h from the difference between each magnification obtained from the magnification and the photograph, or using a non-contact type three-dimensional surface analyzer (WYKO RST / PLUS) For example, a method for obtaining a difference in height between the image portion and the surface of a single dot is used.

  Next, the dispersion ink according to the present invention will be described below.

  The dispersed ink as used in the present invention refers to an ink containing fine solid colorant particles dispersed in a solvent by applying energy to solid colorant particles. The aqueous dispersion ink represents an ink in a state where at least a colorant is dispersed in water and a water-soluble organic solvent.

  As the colorant that can be used in the present invention, a known colorant can be used, but the colorant is a pigment. As the pigment that can be used in the present invention, known colored organic or colored inorganic pigments can be used. For example, azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, perylene and perylene pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc. Examples include polycyclic pigments, dye lakes such as basic dye type lakes and acid dye type lakes, organic pigments such as nitro pigments, nitroso pigments, aniline black, daylight fluorescent pigments, and inorganic pigments such as carbon black. However, the present invention is not limited to these.

  Specific organic pigments are exemplified below.

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

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

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

  Examples of the pigment for black include carbon black.

  As a dispersion method that can be used in the present invention, various types such as a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, and a paint shaker are used alone or in appropriate combination. be able to. Furthermore, for the purpose of removing the coarse particles of the pigment dispersion according to the present invention, it is also an example of a preferred embodiment that is used even when a centrifugal separator or a method of sphering with a filter is used.

  In the present invention, the average dispersed particle diameter of the colorant dispersed in the dispersed ink is 0.05 to 0.2 μm, preferably 0.05 to 0.15 μm, and More preferably, it is 05-0.10 micrometer. When the average particle diameter of the pigment dispersion exceeds 0.2 μm, the glossiness of the image recorded on the glossy medium is deteriorated, and the transparency of the image recorded on the transparency medium is significantly deteriorated. On the other hand, when the average particle diameter of the dispersed pigment particles is less than 0.05 μm, the stability of the pigment particles tends to be deteriorated, resulting in deterioration of the storage stability of the ink.

  The particle size of the pigment dispersed particles can be determined by a commercially available particle size measuring instrument using a light scattering method, an electrophoresis method, a laser Doppler method or the like. It is also possible to obtain a particle image with a transmission electron microscope on at least 100 particles and perform statistical processing on the image using image analysis software such as Image-Pro (manufactured by Media Cybernetics). Is possible.

  In the present invention, the dispersion ink is a so-called aqueous ink containing a water-soluble organic solvent and water in addition to the colorant or pigment.

  Examples of the water-soluble organic solvent that can be used in the present invention include alcohols (for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, hexanol, cyclohexanol, benzyl). Alcohol), polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol Etc.), polyhydric alcohol ethers (for example, ethylene glycol monomethyl ether, ethylene glycol) Ether monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol dimethyl ether, tripropylene glycol dimethyl ether), amines (For example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethyleneto Amines, tetramethylpropylenediamine, etc.), amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.), heterocyclics (eg, 2-pyrrolidone, N-methyl-2-pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, etc.), sulfoxides (eg, dimethyl sulfoxide, etc.), sulfones (eg, sulfolane, etc.), sulfonates (eg, 1-butanesulfonic acid sodium salt, etc.) ), Urea, acetonitrile, acetone and the like.

  In the dispersion ink according to the present invention, in addition to the above description, the following additives may be appropriately selected and used.

  In the present invention, in order to improve the dispersion stability of the pigment, the ink needs to contain a surfactant. Examples of the surfactant preferably used in the ink of the present invention include anionic surfactants such as dialkylsulfosuccinates, alkylnaphthalenesulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkylallyl Nonionic surfactants such as ethers, acetylene glycols, polyoxyethylene / polyoxypropylene block copolymers, cationic surfactants such as alkylamine salts and quaternary ammonium salts, polymer surfactants, etc. It is done. In particular, an anionic surfactant, a nonionic surfactant and a polymer surfactant can be preferably used.

  As the polymeric surfactant referred to in the present invention, the following water-soluble resins can be used, which is preferable from the viewpoint of ejection stability. As the water-soluble resin, styrene-acrylic acid-acrylic acid alkyl ester copolymer, styrene-acrylic acid copolymer, styrene-maleic acid-acrylic acid alkyl ester copolymer, styrene-maleic acid copolymer are preferably used. Polymer, styrene-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-methacrylic acid copolymer, styrene-maleic acid half ester copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer Etc.

  The addition amount of each of the above polymer surfactants with respect to the total amount of the dispersed ink is preferably 0.1 to 10% by mass, more preferably 0.3 to 5% by mass.

  Two or more of these polymer surfactants can be used in combination.

  In the present invention, an electrical conductivity regulator may be used, and examples thereof include inorganic salts such as potassium chloride, ammonium chloride, sodium sulfate, sodium nitrate, and sodium chloride, and aqueous amines such as triethanolamine.

  In addition to the above, the ink in the present invention may contain a preservative, an antifungal agent, a viscosity modifier and the like, if necessary.

  Next, the recording medium according to the present invention will be described below.

  The present invention is characterized in that the recording medium is a void-type recording medium that forms a porous layer containing a hydrophilic binder and fine particles.

  The porous layer according to the present invention is mainly formed from fine particles and a hydrophilic binder.

  As the fine particles that can be used in the present invention, inorganic fine particles and organic fine particles can be used. In particular, the inorganic fine particles have high gloss and high color density, and the fine particles can be easily obtained. preferable. Examples of such inorganic fine particles include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc hydroxide, zinc sulfide, zinc carbonate, White inorganic pigments such as hydrotalcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone, zeolite, magnesium hydroxide, etc. Can be mentioned. The inorganic fine particles can be used as primary particles or in a state where secondary aggregated particles are formed.

  In the present invention, from the viewpoint of obtaining a high-quality print on an inkjet recording medium, alumina, pseudoboehmite, colloidal silica, or fine particle silica synthesized by a vapor phase method is preferable as the inorganic fine particle, and fine particles synthesized by a vapor phase method Silica is particularly preferred. The silica synthesized by this vapor phase method may have a surface modified with Al. The Al content of vapor-phase process silica whose surface is modified with Al is preferably 0.05 to 5% by mass with respect to silica.

  The inorganic fine particles may have any particle diameter, but the average particle diameter is preferably 1 μm or less. If it is 1 micrometer or less, glossiness and coloring property are favorable, Therefore 0.2 micrometer or less is preferable especially and 0.1 micrometer or less is the most preferable. The lower limit of the particle size is not particularly limited, but is preferably approximately 0.003 μm or more, particularly preferably 0.005 μm or more, from the viewpoint of production of inorganic fine particles.

  The average particle size of the inorganic fine particles is obtained as a simple average value (number average) by observing the cross section and surface of the porous layer with an electron microscope and determining the particle size of 100 arbitrary particles. Here, each particle size is expressed by a diameter assuming a circle equal to the projected area.

  Further, the degree of dispersion of the fine particles is preferably 0.5 or less from the viewpoint of glossiness and color developability. If it is 0.5 or less, glossiness and color developability during printing are good. In particular, 0.3 or less is preferable. Here, the degree of dispersion of the fine particles refers to a value obtained by observing the fine particles of the porous layer with an electron microscope in the same manner as obtaining the average particle size and dividing the standard deviation by the average particle size.

  The fine particles may remain as primary particles, or may be present in the porous film as secondary particles or higher-order aggregated particles, but the average particle size is determined by observation with an electron microscope. The particle size of the particles forming independent particles in the porous layer.

  The content of the fine particles in the water-soluble coating solution is 5 to 40% by mass, and particularly preferably 7 to 30% by mass.

  There is no restriction | limiting in particular as a hydrophilic binder contained in a porous layer, A conventionally well-known hydrophilic binder can be used, For example, gelatin, polyvinylpyrrolidone, polyethylene oxide, polyacrylamide, polyvinyl alcohol etc. are used. Polyvinyl alcohol is particularly preferred.

  Polyvinyl alcohol has an interaction with inorganic fine particles, has a particularly high holding power with respect to inorganic fine particles, and is a polymer having a relatively low humidity dependency of hygroscopicity, and has a relatively low shrinkage stress during coating and drying. Since it is small, the aptitude with respect to the crack at the time of application | coating drying which is a subject of this invention is excellent. Examples of the polybilyl alcohol preferably used in the present invention include, in addition to ordinary polyvinyl alcohol obtained by hydrolysis of polyvinyl acetate, modified polyvinyl alcohol having a terminal cation modified, anion-modified polyvinyl alcohol having an anionic group, and the like. Polyvinyl alcohol is also included.

  As the polyvinyl alcohol obtained by hydrolysis of vinyl acetate, those having an average degree of polymerization of 300 or more are preferably used, and those having an average degree of polymerization of 1000 to 5000 are particularly preferably used. The saponification degree is preferably 70 to 100%, particularly preferably 80 to 99.5%.

  Examples of the cation-modified polyvinyl alcohol have primary to tertiary amino groups and quaternary ammonium groups in the main chain or side chain of the polyvinyl alcohol as described in JP-A-61-110483. 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-(-methacrylamidopropyl) ammonium chloride, N- (1,1 -Dimethyl-3-dimethylaminopropyl) acrylamide and the like.

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

  Polyvinyl alcohol can also use 2 or more types together, such as a polymerization degree and a different kind of modification | denaturation. In particular, when polyvinyl alcohol having a degree of polymerization of 2000 or more is used, 0.05 to 10% by mass of polyvinyl alcohol having a degree of polymerization of 1000 or less is preferably 0.05 to 10% by mass in the inorganic fine particle dispersion. It is preferable to add polyvinyl alcohol having a degree of polymerization of 2000 or more after adding 1 to 5% by mass without significant thickening.

  The ratio of the fine particles to the hydrophilic binder in the porous layer is preferably 2 to 20 times in terms of mass ratio. When the mass ratio is less than twice, not only does the porosity of the porous layer decrease and it becomes difficult to obtain a sufficient void volume, but an excessive hydrophilic binder swells during ink jet recording to close the void, It becomes a factor of decreasing the ink absorption speed. On the other hand, when this ratio exceeds 20 times, cracks are likely to occur when the porous layer is applied as a thick film, which is not preferable. The ratio of the fine particles to the particularly preferred hydrophilic binder is 2.5 to 12 times, most preferably 3 to 10 times.

  As the support used in the inkjet recording medium of the present invention, a water-absorbing support (for example, paper) or a non-water-absorbing support can be used. From the viewpoint of obtaining a higher-quality print, non-water-absorbing support. An ionic support is preferred.

  With a water-absorbing support, not only is it difficult to obtain a high-quality print, but each overcoated additive component diffuses into the paper after coating, resulting in a loss of the original effect of the additive.

  Examples of the non-water-absorbing support preferably used include, for example, polyester film, diacetate film, triatesate film, polyolefin film, acrylic film, polycarbonate film, polyvinyl chloride film, polyimide film, cellophane, A transparent or opaque film made of a material such as celluloid, or a resin-coated paper in which both surfaces of a base paper are coated with a polyolefin resin coating layer, so-called RC paper, or the like is used.

  Various additives can be added to the water-soluble coating liquid for forming the porous layer. Such additives include, for example, cationic mordants, crosslinking agents, surfactants (cations, nonions, anions, amphoterics), white color tone modifiers, fluorescent whitening agents, antifungal agents, viscosity modifiers, low boiling points. Organic solvents, high-boiling organic solvents, latex emulsions, anti-fading agents, UV absorbers, polyvalent metal compounds (water-soluble or water-insoluble), matting agents, silicone oils, etc., among which cationic mordants are used after printing It is preferable in order to improve the water resistance and moisture resistance.

  As the cationic mordant, a polymer mordant having a primary to tertiary amino group and a quaternary ammonium base is used, but has a quaternary ammonium base because of less discoloration and deterioration of light resistance over time. Polymer mordants are preferred.

  A preferred polymer mordant is obtained as a homopolymer of a monomer having the quaternary ammonium base, a copolymer with another monomer, or a condensation polymer.

  It is also particularly preferable to include a hydrophilic binder crosslinking agent. The water resistance of the porous layer is improved by the crosslinking agent, and the ink absorption speed is improved because the swelling of the hydrophilic binder is suppressed during ink jet recording.

  As the crosslinking agent, conventionally known crosslinking agents can be used, and inorganic crosslinking agents (for example, chromium compounds, aluminum compounds, zirconium compounds, boric acids, etc.) and organic crosslinking agents (for example, epoxy crosslinking agents, Isocyanate crosslinking agents, aldehyde crosslinking agents, N-methylol crosslinking agents, acryloyl crosslinking agents, vinyl sulfone crosslinking agents, active halogen crosslinking agents, carbodiimide crosslinking agents, ethyleneimino crosslinking agents, etc.) be able to.

  These crosslinking agents are generally 1 to 50% by mass, preferably 2 to 40% by mass, based on the hydrophilic binder.

  When the hydrophilic binder is polyvinyl alcohol and the fine particles are silica, inorganic crosslinking agents such as boric acids and zirconium compounds and epoxy crosslinking agents are particularly preferable as the crosslinking agent.

  The coating method that can be used in the production of the recording medium according to the present invention can be appropriately selected from known methods, such as gravure coating method, roll coating method, rod bar coating method, air knife coating method, spraying. A coating method, an extrusion coating method, a curtain coating method, or an extrusion coating method using a hopper described in US Pat. No. 2,681,294 is preferably used.

  The porous layer according to the recording medium of the present invention may be a single layer or a multilayer, and in the case of a multilayer structure, it is preferable to apply all the layers simultaneously from the viewpoint of reducing the manufacturing cost.

  The ink jet head used in the ink jet image recording method of the present invention may be an on-demand system or a continuous system. In addition, as a discharge method, an electro-mechanical conversion method (for example, a single cavity type, a double cavity type, a bender type, a piston type, a shear mode type, a shared wall type, etc.), an electro-thermal conversion method (for example, a thermal type) Specific examples include an ink jet type, a bubble jet (registered trademark) type, an electrostatic suction type (for example, an electric field control type, a slit jet type, etc.) and a discharge type (for example, a spark jet type). However, any discharge method may be used.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. In the examples, “%” represents mass% unless otherwise specified.

<Production of recording medium>
[Preparation of recording medium 1]
[Preparation of silica dispersions D1 and D2]
25% gas phase method silica (Nippon Aerosil Co., Ltd .: A200) having an average primary particle size of about 0.012 μm uniformly dispersed in advance, water-soluble fluorescent whitening agent UVITEXNFW LIQUID (Ciba Specialty Chemicals) 400% of silica dispersion B1 containing 0.3% (pH = 2.3, containing 1% by mass of ethanol), 12% of cationic polymer P-1, 10% of n-propanol and 2% of ethanol It added, stirring at 3000 rpm at room temperature to 110 L of aqueous solution C1 (pH = 2.5, 2 g of defoaming agent SN381 made by Sannobuco) was contained. Next, 54 L of a mixed aqueous solution A1 (concentration of 3% each) in a 1: 1 mass ratio of boric acid and borax was gradually added with stirring.

Subsequently, it disperse | distributed by the pressure of 3000 N / cm < ² > with the high-pressure homogenizer by Sanwa Kogyo Co., Ltd., the whole quantity was finished to 630L with pure water, and the substantially transparent silica dispersion D1 was obtained.

  On the other hand, 400 L of the silica dispersion B1 was added to 120 L of an aqueous solution C2 (pH = 2.5) containing 12% of the cationic polymer P-2, 10% of n-propanol and 2% of ethanol at 3000 rpm at room temperature. The mixture was added with stirring, and then 52 L of the mixed aqueous solution A1 was gradually added with stirring.

Subsequently, it disperse | distributed by the pressure of 3000 N / cm < ² > with the high-pressure homogenizer by Sanwa Kogyo Co., Ltd., the whole quantity was finished to 630L with pure water, and the substantially transparent silica dispersion D2 was obtained.

  The silica dispersions D1 and D2 were filtered using a TCP-30 type filter manufactured by Advantech Toyo Co., Ltd. having a filtration accuracy of 30 μm.

[Preparation of oil dispersion]
Gelatin aqueous solution containing 20 kg of diisodecyl phthalate and 20 kg of antioxidant (AO-1) dissolved in 45 kg of ethyl acetate by heating, 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 entire amount was finished to 300 L with pure water to prepare an oil dispersion.

(Preparation of coating solution)
Using the dispersions prepared above, the additives described below were sequentially mixed to prepare a coating solution. In addition, each addition amount was displayed by the quantity per 1L of coating liquids.

(First layer coating solution: bottom layer)
Silica dispersion D1 580ml
Polyvinyl alcohol (Kuraray Co., Ltd .: PVA203) 10% aqueous solution
5ml
Polyvinyl alcohol (average polymerization degree: 3800 saponification degree 88%)
290ml of 6.5% aqueous solution
Oil dispersion 30ml
Latex dispersion (AE803, Showa Polymer Co., Ltd.) 42ml
8.5 ml of ethanol
Finish the whole volume to 1000ml with pure water (2nd layer coating solution)
Silica dispersion D1 600ml
Polyvinyl alcohol (Kuraray Co., Ltd .: PVA203) 10% aqueous solution
5ml
Polyvinyl alcohol (average polymerization degree: 3800 saponification degree 88%)
6.5% aqueous solution 270ml
Oil dispersion 20ml
Latex dispersion (Showa Polymer Co., Ltd .: AE803) 22ml
8 ml of ethanol
Finish the whole volume to 1000ml with pure water (3rd layer coating solution)
Silica dispersion D2 630ml
Polyvinyl alcohol (Kuraray Co., Ltd .: PVA203) 10% aqueous solution
5ml
Polyvinyl alcohol (average polymerization degree: 3800 saponification degree 88%)
6.5% aqueous solution 270ml
Oil dispersion 10ml
Latex dispersion (AE803, Showa Polymer Co., Ltd.) 5ml
Ethanol 3ml
Finish the whole volume to 1000ml with pure water (4th layer coating solution: top layer)
Silica dispersion D2 660ml
Polyvinyl alcohol (Kuraray Co., Ltd .: PVA203) 10% aqueous solution
5ml
Polyvinyl alcohol (average polymerization degree: 3800 saponification degree 88%)
250% 6.5% aqueous solution
3 ml of 4% aqueous solution of betaine surfactant-1
2 ml of 25% aqueous solution of saponin
Ethanol 3ml
Finish the whole volume to 1000ml with pure water

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

[Recording medium application]
Next, four layers of each of the above coating solutions were simultaneously coated on a paper support coated with polyethylene on both sides at 40 ° C. using a slide hopper type coater so that the wet film thickness described below was obtained.

<Wet film thickness>
First layer: 42 μm
Second layer: 39 μm
Third layer: 44 μm
Fourth layer: 38 μm
As the paper support, the following support wound in a roll shape having a width of about 1.5 m and a length of about 4000 m was used.

The paper support used was 8% water content, 170g basis weight, photographic base paper surface was extruded and melt coated with polyethylene containing 6% anatase-type titanium oxide at a thickness of 35μm, and the back side was thick. 40 μm of polyethylene was extruded and melt coated. After the corona discharge on the front side, polyvinyl alcohol (PVA235 manufactured by Kuraray Co., Ltd.) was coated with an undercoat layer at 0.05 g per 1 m ² of the recording medium, and after the corona discharge processing on the back side, Tg was about A back layer containing about 0.4 g of a 80 ° C. styrene / acrylate ester latex binder, 0.1 g of an antistatic agent (cationic polymer) and 0.1 g of about 2 μm of silica as a matting agent was applied.

  Drying after application of the ink receiving layer coating liquid is performed by passing through a cooling zone maintained at 5 ° C. for 15 seconds to lower the temperature of the film surface to 13 ° C., and then setting the temperature of a plurality of drying zones as appropriate. Then, after drying, it was wound up into a roll to obtain a comparative recording medium 1. As a result of measuring the center line average surface roughness (Ra value A) of the recording medium 1 by the method described later, it was 0.21 μm.

[Preparation of recording medium 2]
In the production of the recording medium 1, a recording with an Ra value A of 0.46 μm was performed in the same manner except that the addition amount of the inorganic fine particles (silica dispersions D1 and D2) and the hydrophilic binder (polyvinyl alcohol) in each layer was appropriately changed. Medium 2 was produced.

<Preparation of ink>
[Preparation of Pigment Ink 1]
Pigment ink 1 comprising a yellow pigment was prepared according to the method described below.

(Preparation of yellow pigment dispersion 1)
C. I. Pigment Yellow 128 (CROMOPHTAL YELLOW 8G-CF Ciba Specialty Chemicals)
100g
Glycerin 100g
Ion exchange water 130g
Each of the above additives was mixed, dispersed using a horizontal bead mill (Ashizawa's System Zetamini) filled with 0.3 mm zirconia beads at a volume ratio of 60%, fractionated by centrifugation, and the average particle size was A 95 nm yellow pigment dispersion 1 was obtained. The particle size was measured using a Zetasizer 1000 manufactured by Malvern.

(Preparation of ink)
160 g of yellow pigment dispersion 1 (average particle size: 95 nm)
Diethylene glycol 180g
Glycerin 80g
Perex OT-P (manufactured by Kao Corporation) 5g
Proxel GXL (Zeneca) 2g
Each of the above additives was finished to 1000 g with ion-exchanged water, and passed through a 1 μm Millipore filter twice to prepare pigment ink 1 as a yellow pigment ink.

[Preparation of pigment inks 2 to 12]
In the preparation of the pigment ink 1, C.I. I. Pigment Yellow 128 (average particle size 95 nm) was changed to the pigments listed in Table 1, and the dispersion conditions were adjusted as appropriate to obtain the same average particle size as shown in Table 1. Pigment inks 2 to 12 were prepared.

<< Preparation of sample for evaluation >>
(Preparation of image recording samples 1 to 12)
Using the pigment inks 1 to 12 and the recording medium 1 produced as described above, an image was output in accordance with the method described below, and image recording samples 1 to 12 were produced.

  As an image recording method, an on-demand type ink jet printer having a maximum recording density of 720 × 720 dpi equipped with a piezo-type head having a nozzle hole diameter of 20 μm, a driving frequency of 12 kHz, 128 nozzles per color, and a nozzle density between the same colors of 180 dpi. Were used as output images, each monochrome image pattern giving a reflection density of 1.0 on each recording medium and each monochrome image pattern in which each dot was discretely recorded independently of each other. In the present invention, dpi refers to the number of dots per 2.54 cm (1 inch).

<Measurement of centerline average surface roughness Ra of non-image portion and image recording portion>
For the output image having a reflection density of 1.0, the center line average surface roughness Ra of the non-image portion and the image recording portion was measured according to the method described below.

  As a surface roughness measurement system, Surfcom 500B (manufactured by Tokyo Seimitsu Co., Ltd.) was used, and the center line average surface roughness was measured at 64 points for each of the non-image portion and the image recording portion, and the center of the non-image portion and the image recording portion. The line average surface roughness Ra values A and B were used.

  In addition, the measurement was performed by dividing each sample of 40 cm × 40 cm into 64 grids at intervals of 5 cm and measuring the center of each square region under the conditions of a measurement length of 5 mm and a cutoff value of 0.8 mm. Ra was defined according to JIS surface roughness (B0601).

<Measurement of average height difference between non-image area and single dot surface>
Using the monochromatic image pattern in which the output dots are discretely recorded independently of each other, the average height difference h between the non-image portion not printed at all and the surface of each individual dot is determined according to the following method. It was measured.

  The height difference h is measured using a non-contact type three-dimensional surface analysis device (WYKO RST / PLUS) by placing all dots in a 312 × 231.7 μm measurement area and measuring the height difference for 50 dots of each ink. The arithmetic average value was defined as the average height difference h.

<Evaluation of glossiness>
The glossiness of the obtained image area and non-image area was evaluated by visual evaluation according to the following criteria.

◎: The image part has a significant glossiness, and the difference from the non-image part is not bothered. ○: The image part has a glossy feeling, and the difference in glossiness from the non-image part does not matter. △: The image is glossy. There is little feeling, and I am worried about the difference from the non-image part. X: The image has no glossiness and the difference from the non-image part is remarkable. <Evaluation of smoothness>
The smoothness of the obtained image part and non-image part was evaluated by visual evaluation according to the following criteria.

A: Excellent smoothness of the image area and no difference in smoothness from the non-image area. O: Excellent smoothness in the image area, no difference in smoothness from the non-image area. Δ: The smoothness of the image is slightly inferior, and the difference from the non-image part is a concern. ×: The image has no smoothness and the difference from the non-image part is remarkable (production of image recording samples 13 to 24)
Next, image recording samples 13 to 20 were prepared in the same manner as in the preparation of the image recording samples 1 to 8, except that the recording medium 1 was changed to the recording medium 2 using the pigment inks 1 to 8. Further, with respect to the pigment inks 9 to 12 prepared above, an image was formed on the recording medium 2 by the same method using the pigment inks 13 to 16 in which the average particle diameters were changed as shown in Table 2. Image recording samples 21 to 24 were prepared. Subsequently, for each image recording sample, the center line average surface roughness Ra of the non-image portion and the image recording portion, the average height difference between the non-image portion and the surface of the image portion, and the glossiness and smoothness are measured by the method described above. Was evaluated.

  Tables 1 and 2 show the results obtained as described above.

  As is clear from the results in Tables 1 and 2, the ratio of the Ra value B (μm) of the image recording portion to the Ra value A (μm) of the non-image portion is 0.7 or more and 1.8 or less. It can be seen that this sample is superior in gloss and smoothness to the comparative product. Furthermore, in the sample of the present invention, it was confirmed that the effect was further exhibited by setting the average height difference between the non-image area and the image area surface to 2.0 μm or less.

Example 2
Image recording was performed by the method described below so that the pigment inks 1 to 16 prepared in Example 1 and the recording media 1 and 2 were in the combinations shown in Table 3, and output images 25 to 29 were produced. .

(Image recording method)
As an image recording method, an on-demand type ink jet printer having a maximum recording density of 720 × 720 dpi mounted with a piezo head having a nozzle hole diameter of 20 μm, a driving frequency of 12 kHz, 128 nozzles per color, and a nozzle density of 180 dpi between the same colors. Each color image pattern of yellow, magenta, cyan and black giving a reflection density of 1.0 on each recording medium and high-definition color digital standard image data “N5 bicycle” issued by the Japan Standards Association. (Issued in December 1995) was used as the output image.

(Evaluation of each characteristic value of the formed image)
<Measurement of centerline average surface roughness Ra of non-image area and image recording area>
Each monochromatic part was measured by the same method as in Example 1.

<Measurement of average height difference between non-image area and image area surface>
Each monochromatic part was measured by the same method as in Example 1.

<Evaluation of gloss and smoothness>
Evaluation was performed by the same method and criteria as in Example 1.

<Image quality evaluation>
The output image of the high-definition color digital standard image data “N5 Bicycle” (issued in December 1995) produced by the above image output method is selected according to the following criteria by selecting 10 panelists as appropriate and visually observing them. The texture was evaluated. The viewing distance at the time of evaluation was 300 to 400 mm, and the illuminance was 1000 ± 50 lux.

5: The output image has texture, depth, and luxury, and the image quality is close to that of a photographic tone 4: The texture, depth, and luxury are felt in the output image, and the image quality is close to photographic tone 3: The output image The image quality is slightly inferior to photographic tone, slightly lacking in texture, depth, and luxury 2: The output image is inferior in texture, depth, luxury, and the image quality is inferior to photographic tone 1: In the output image There is no texture, depth and luxury at all, and the image quality is far from photographic. The evaluation was made by averaging the evaluation values of each panel and making it a scale for texture evaluation.

  The results obtained as described above are shown in Table 3.

  As apparent from Table 3, even in a color image using a plurality of inks, the ratio of the Ra value B (μm) of the image recording portion to the Ra value A (μm) of the non-image portion is 0.7 or more, 1 It can be seen that the sample of the present invention having a particle size of .8 or less has good gloss and smoothness and excellent texture compared to the comparative product.

Claims (6)

It contains fine particles having an average particle diameter of 0.003 μm to 0.1 μm and a hydrophilic binder, the weight ratio of the fine particles to the hydrophilic binder is 2.5 to 12, and the centerline average surface roughness Ra value A is In an ink jet recording method in which a dispersed ink of each color in which a pigment is dispersed in a solvent so as to have an average dispersion diameter of 0.05 to 0.2 μm is attached to a recording medium having a diameter of 0.21 to 0.46 μm. When image recording portions having a reflection density of 1.0 for each color are created, the center line average surface roughness Ra value B of the image recording portions for each color is 0.7 Ra value A to 1.8 Ra value. An ink jet recording method, wherein recording is performed using each color ink to be A. The inkjet recording method according to claim 1, wherein the dispersed ink contains at least a pigment, a water-soluble organic solvent, and water. 2. The ink jet recording method according to claim 1, wherein a weight ratio of the fine particles to the hydrophilic binder is 3 to 10. It contains fine particles having an average particle diameter of 0.003 μm to 0.1 μm and a hydrophilic binder, the weight ratio of the fine particles to the hydrophilic binder is 2.5 to 12, and the centerline average surface roughness Ra value A is Recording is performed by an ink jet recording method in which a dispersed ink of each color in which a pigment is dispersed in a solvent so as to have an average dispersion diameter of 0.05 to 0.2 μm is attached to a recording medium having a diameter of 0.21 to 0.46 μm. When an image recording portion having a reflection density of 1.0 for each color is created, the center line average surface roughness Ra value B of the image recording portion for each color is 0. A recorded matter recorded using ink of each color having a 7Ra value A to 1.8Ra value A. The recorded matter according to claim 4, wherein the dispersed ink contains at least a pigment, a water-soluble organic solvent, and water. The recorded matter according to claim 4, wherein a weight ratio of the fine particles to the hydrophilic binder is 3 to 10.