JP2007136854A - Inkjet recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording material using a support made up of a pulp fiber of a large average fiber length, preventing dazzling of a printing part while retaining a peculiar aesthetic property of the support, and excellent color development. <P>SOLUTION: This inkjet recording material is based on an inkjet recording paper with an ink acceptance layer formed on the support made up of the pulp fiber with not less than 1 mm average fiber length. In addition, the ink acceptance layer contains an inorganic fine particle with not more than 500 nm average secondary particle diameter and a cationized matting agent. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet recording material using a support composed of pulp fibers having a long average fiber length, and maintains the unique texture of the support and prevents glare in the printed portion, and is excellent in color development. The present invention relates to an inkjet recording material.

  In recent years, the ink jet recording technology has been remarkably improved. For example, in the field of photographic output, the resolution and weather resistance of output images are increasing to a level comparable to that of conventional silver salt type photographic prints. On the other hand, with the advancement of technology, its applications are becoming more and more diverse, and new products are being developed one after another, including hobby and taste fields. In particular, recently, not only the hard surface but also the recording material to be output have been known to use various supports in addition to the conventional paper or resin-coated paper. Among them, a recording material using a support composed of fibers having a relatively long fiber length, such as cotton paper, has attracted particular attention for fine art applications due to an appropriate texture derived from the long fiber length.

  For example, in JP-A-2002-36714 (Patent Document 1) and JP-A-2002-219856 (Patent Document 2), an ink receiving layer containing inorganic pigment particles and a binder is provided on a support made of cotton paper. A recording material is disclosed. However, these recording materials focus on the robustness of the recording materials themselves, and the current situation is that they have not caught up with recent remarkable advances in inkjet recording technology in terms of image quality and color development. Further, since silica particles having a relatively large particle size are used as the pigment constituting the ink receiving layer, the surface is completely matte, and there is a problem that a desired surface feeling cannot be obtained depending on the output image. .

  On the other hand, as a method for obtaining a recording material with high image quality and high color developability, for example, Japanese Patent Application Laid-Open No. 2004-255596 (Patent Document 3) uses a gas phase method silica, and Japanese Patent Application Laid-Open No. 2004-291521 (Patent Document 4). ) Describes a method of pulverizing wet silica. In these methods, the particle size of the pigment constituting the ink receiving layer is reduced, thereby suppressing the sinking of the ink coloring material into the receiving layer and increasing the color development by reducing the haze of the receiving layer itself. However, if an ink receiving layer obtained by these methods is provided on a support made of pulp fibers having a long fiber length such as cotton paper as it is, a high image quality is surely obtained, but the texture of the support is excessively emphasized. The texture will be lost. In addition, recording materials used for such special applications are often printed mainly with pigment ink from the viewpoint of weather resistance, and the gloss of only the printed area is improved due to the influence of the polymer component in the pigment ink. There is a problem that glare occurs.

A method for adjusting gloss by adding particles having a relatively large particle diameter, called a matting agent, is widely known (Patent Document 5). However, the addition of the matting agent promotes the sinking of the ink coloring material described in the previous section and causes the color reduction due to the increase in haze of the receiving layer, so that it is difficult to achieve both surface property adjustment and color improvement.
JP 2002-36714 A (2nd to 5th terms) Japanese Patent Laid-Open No. 2002-219856 (2nd to 5th terms) Japanese Patent Application Laid-Open No. 2004-255596 (Items 2 to 6) Japanese Patent Application Laid-Open No. 2004-291521 (2nd to 4th terms) JP 2001-347753 A (2nd to 4th terms)

  An object of the present invention is an ink jet recording material using a support made of a pulp fiber having a long average fiber length, while maintaining a unique texture of the support and preventing glare of the printed portion, and being excellent in color development. An inkjet recording material is provided.

The above object of the present invention has been basically achieved by the following invention.
1) Ink jet recording paper in which an ink receiving layer is provided on a support composed of pulp fibers having an average fiber length of 1 mm or more, and the ink receiving layer has inorganic fine particles having an average secondary particle size of 500 nm or less and cationization An ink jet recording material comprising a matting agent prepared.

2) The inkjet recording material as described in 1 above, wherein the average particle size of the matting agent is 1 μm or more and 20 μm or less.

  According to the present invention, in an inkjet recording material using a support made of pulp fibers having a long average fiber length, while maintaining the unique texture of the support and preventing glare of the printed portion, ink absorbency, color development, An ink jet recording material having excellent pigment ink rubability can be provided.

Hereinafter, the present invention will be described in detail.
The present invention is directed to a support composed of pulp fibers having an average fiber length of 1 mm or more in terms of texture. In general, it is known that it is preferable to use non-woody pulp in order to secure a certain fiber length. As a pulp type, cotton, cotton, straw, bagasse, jute, hemp, bamboo, etc. Non-woody pulp, regenerated fiber such as rayon, lyocell, and cupra can be used. Of course, a wood-based natural pulp may be appropriately mixed and used. Natural pulp used at this time includes normal bleaching treatment of chlorine, hypochlorite, chlorine dioxide bleaching, alkali extraction or alkali treatment, and if necessary, oxidative bleaching treatment with hydrogen peroxide, oxygen, etc. Wood pulp of softwood pulp, hardwood pulp, softwood hardwood mixed pulp subjected to the combination treatment is advantageously used, and various kinds such as kraft pulp, sulfite pulp, and soda pulp can be used.

  The support used in the present invention can contain various additives at the time of preparing the paper slurry. As sizing agent, fatty acid metal salt or fatty acid, alkyl ketene dimer emulsion described or exemplified in JP-B-62-7534, epoxidized higher fatty acid amide, alkenyl or alkyl succinic anhydride emulsion, rosin derivative, etc., dry paper Anionic, cationic or amphoteric polyacrylamide, polyvinyl alcohol, cationized starch, vegetable galactomannan, etc. as a power enhancer, polyamine polyamide epichlorohydrin resin, etc. as a wet paper strength enhancer, clay, kaolin, carbonic acid as filler Calcium, titanium oxide, etc., fixing agents such as water-soluble aluminum salts such as aluminum chloride and sulfuric acid bands, etc., pH regulators such as caustic soda, sodium carbonate, sulfuric acid, etc. Other JP-A-63-204251, JP-A-1- 266537 Colored pigment according or illustrated in Publication, colored dye, that allowed to contain appropriately combining a fluorescent whitening agent is advantageous.

  The support of the present invention can be produced using a normal wet type wire type paper machine, for example, a Ford linear type long net paper machine, an on-top paper machine, a multi-layer type round net paper machine, etc. it can.

  The support in the present invention can be provided with an undercoat layer before providing the ink receiving layer. Suitable binders for impregnation or coating as the undercoat layer are water-soluble polymers or hydrophilic colloids, emulsions, and latexes. Examples of water-soluble polymers or hydrophilic colloids include starch polymers, polyvinyl alcohol polymers, gelatin polymers, polyacrylamide polymers, cellulose polymers, polysaccharides such as xanthan gum, and casein described or exemplified in JP-A-1-266537. Examples of emulsions and latexes include petroleum resin emulsions, and at least ethylene and acrylic acid (or methacrylic acid) described or exemplified in JP-A Nos. 55-4027 and 1-180538. Copolymer emulsion or latex, styrene-butadiene, styrene-acrylic, vinyl acetate-acrylic, ethylene-vinyl acetate, butadiene-methyl methacrylate copolymer and their carbo Emulsion or latex of a modified copolymer and the like.

  Examples of the pigment applied as the undercoat layer include calcium carbonate, zinc oxide, magnesium oxide, activated clay, kaolin, talc, titanium oxide, zirconium oxide, cerium oxide, and aluminum hydroxide.

  Examples of the inorganic fine particles used in the ink receiving layer of the present invention include various known fine particles such as silica, alumina, alumina hydrate, calcium carbonate, magnesium carbonate, and titanium dioxide. From the viewpoint of ink absorbability and productivity, silica is used. Fine particles are preferable, and it is particularly preferable to use amorphous synthetic silica. From the viewpoint of color developability, it is important to use the secondary particle size as at least 500 nm.

  Amorphous synthetic silica can be roughly classified into wet method silica and gas phase method (dry method) silica depending on the production method. Wet silica is produced by reacting sodium silicate and sulfuric acid under alkaline conditions and agglomerating and precipitating silica particles that have grown, and by reacting sodium silicate and sulfuric acid under acidic conditions. “Gel method silica” and “sol method silica” produced by heating and aging silica sol obtained through metathesis by acid of sodium silicate or ion exchange resin layer. “Sedimentation method silica” is characterized in that particles that are relatively easy to pulverize can be obtained by forming a gentle secondary aggregate. For example, Tosoh Silica Co., Ltd. as a nip seal, Tokuyama Co., Ltd. It is commercially available as a fine seal. “Silica gel method” dissolves small silica particles during ripening and reprecipitates the primary particles to bond between the primary particles of the large particles, thus forming relatively hard agglomerated particles with an internal void structure. For example, it is commercially available as Mizusukasil from Mizusawa Chemical Industry Co., Ltd. and as a silo jet from Grace Japan Co., Ltd. “Sol silica” is also known as colloidal silica, and is commercially available, for example, as Snowtex from Nissan Chemical Industries, Ltd.

  Of the wet process silicas, in the present invention, precipitated silicas and gel process silicas having an average primary particle size of 50 nm or less, preferably 3 to 40 nm are preferable from the viewpoint of ink absorbability and color developability. From the viewpoint of cracks and cost, precipitated silica is more preferably used. Since the wet process silica produced by the usual method has an average secondary particle size of 1 μm or more, in order to obtain fine particles having an average secondary particle size of 500 nm or less according to the present invention, this is finely pulverized by the method described later. And use it. The average primary particle size in the present invention is based on a known method of observing with an electron microscope (SEM and TEM), and the average secondary particle size is measured with a laser diffraction / scattering type particle size distribution measuring device. It is based on a known method for measuring.

  In the present invention, gas phase method silica can also be preferably used. Vapor phase silica is also called a dry method as opposed to a wet method, and is generally made by a flame hydrolysis method. Specifically, a method of making silicon tetrachloride by burning with hydrogen and oxygen is generally known, but silanes such as methyltrichlorosilane and trichlorosilane can be used alone or silicon tetrachloride instead of silicon tetrachloride. Can be used in a mixed state. Vapor phase silica is commercially available from Nippon Aerosil Co., Ltd. as Aerosil, and from Tokuyama Co., Ltd. as Reolosil. The average particle size of the primary particles of the vapor phase silica used in the present invention is preferably 30 nm or less, and more preferably 15 nm or less. Similarly to the wet method silica, the vapor phase method silica can be finely pulverized by the method described later to obtain fine particles having an average secondary particle size of 500 nm or less of the present invention.

  As a method for pulverizing silica particles, a wet dispersion method in which silica dispersed in an aqueous medium is mechanically pulverized can be preferably used. The wet dispersion of the present invention is carried out through a two-stage process, that is, after mixing the silica and water to obtain an aqueous slurry (coarse dispersion process or primary dispersion process), pulverization is performed using a more powerful disperser. It processes by the process (secondary dispersion | distribution process) to perform. Specifically, water, silica particles, and a cationic compound are first mixed (regardless of the order of addition), and a sawtooth blade type disperser, a propeller blade type disperser, or a rotor stator type disperser is used. The primary dispersion process is performed using at least one of the dispersing devices to obtain a primary dispersion. The cationic compound acts as a dispersion aid at the time of wet dispersion and as a fixing agent after the ink receiving layer is formed, and the addition amount is preferably 0.5 to 20% by mass with respect to the silica particles, and 1 to 10% by mass. % Is more preferable. By setting it in this range, the viscosity of the primary dispersion does not become too high, and the solid content concentration can be increased. Further, for example, a low boiling point solvent such as ethyl alcohol may be added as necessary, and there is no particular limitation on the timing of addition and the order of addition. When a low boiling point organic solvent is added, the amount added is preferably 10% by mass or less of the total weight of the primary dispersion. The solid dispersion concentration of the primary dispersion of the present invention is preferably high, but if the concentration is too high, it becomes impossible to disperse. Therefore, the preferable range is 20 to 60% by mass, and more preferably 25 to 50% by mass.

  In addition, when dispersing the wet process silica, it is preferable to contain in the dispersion a substance that can react with sulfate ions to form a water-insoluble or hardly water-soluble salt. By doing so, when forming the ink-receiving layer coating solution, it is possible to suppress agglomeration due to the sulfate ions originally contained in the wet process silica and causing defects during coating. The partner that reacts with sulfate ions to form a water-insoluble or poorly water-soluble salt is not particularly limited as long as the solubility product of the sulfate produced by the reaction is small, but not only the solubility product of sulfate is small but also other negative ions. Barium salt is preferable because a salt having high solubility can be obtained and a salt having high solubility can be obtained relatively inexpensively. Barium chloride salt (dihydrate) is particularly preferable. The addition amount of the barium salt advantageously used in the present invention is preferably in the range of 0.2 to 20 g, more preferably 0.5 to 15 g, particularly preferably 0.8 to 1 kg of silica solid content in the silica dispersion. 12 g is preferred.

  Next, by applying a stronger mechanical means to the primary dispersion obtained by the above method, a silica fine particle dispersion having an average secondary particle diameter of 500 nm or less is obtained. As a mechanical means, a known method can be adopted, for example, a media mill such as a ball mill, a bead mill, a sand grinder, a high pressure homogenizer, a pressure disperser such as an ultra high pressure homogenizer, an ultrasonic disperser, a thin film circulation disperser, etc. Can be used.

  Examples of the cationic compound that can be used for the silica dispersion include a cationic polymer and a water-soluble metal compound. Examples of the cationic polymer include polyethyleneimine, polydiallylamine, polyallylamine, alkylamine polymer, JP-A-59-20696, JP-A-59-33176, JP-A-59-33177, JP-A-59-155088. JP, 60-11389, JP 60-49990, JP 60-83882, JP 60-109894, JP 62-198493, JP 63-49478, 1 described in JP-A-63-115780, JP-A-63-280681, JP-A-1-40371, JP-A-6-234268, JP-A-7-125411, JP-A-10-193976, etc. A polymer having a tertiary amino group or a quaternary ammonium base is preferably used. In particular, diallylamine derivatives are preferably used as the cationic polymer. In terms of dispersibility and dispersion viscosity, the molecular weight of these cationic polymers is preferably about 2,000 to 100,000, and particularly preferably about 2,000 to 30,000.

  Examples of the water-soluble metal compound include water-soluble polyvalent metal salts. Examples thereof include water-soluble salts of metals selected from calcium, barium, manganese, copper, cobalt, nickel, aluminum, iron, zinc, titanium, zirconium, chromium, magnesium, tungsten, and molybdenum. Specifically, for example, calcium acetate, calcium chloride, calcium formate, calcium sulfate, barium acetate, barium sulfate, barium phosphate, manganese chloride, manganese acetate, manganese formate dihydrate, manganese ammonium sulfate hexahydrate, chloride chloride Dicopper, ammonium copper (II) chloride dihydrate, copper sulfate, cobalt chloride, cobalt thiocyanate, cobalt sulfate, nickel sulfate hexahydrate, nickel chloride hexahydrate, nickel acetate tetrahydrate, nickel sulfate Ammonium hexahydrate, nickel amidosulfate tetrahydrate, aluminum sulfate, aluminum sulfite, aluminum thiosulfate, polyaluminum chloride, aluminum nitrate nonahydrate, aluminum chloride hexahydrate, ferrous bromide, ferric chloride Ferrous, ferric chloride, ferrous sulfate, ferric sulfate, zinc bromide, zinc chloride, zinc nitrate six Japanese products, zinc sulfate, zinc p-phenolsulfonate, titanium chloride, titanium sulfate, titanium lactate, zirconium acetate, zirconium chloride, zirconium chloride octahydrate, zirconium zirconium chloride, chromium acetate, chromium sulfate, magnesium sulfate, chloride Magnesium hexahydrate, magnesium citrate nonahydrate, sodium phosphotungstate, sodium tungsten citrate, 12 tungstophosphoric acid n hydrate, 12 tungstosilicic acid 26 hydrate, molybdenum chloride, 12 molybdophosphate n A hydrate etc. are mentioned.

  Among the above water-soluble polyvalent metal compounds, compounds made of aluminum or a Group 4A metal (for example, zirconium or titanium) of the periodic table are preferable. Particularly preferred is a water-soluble aluminum compound. As a water-soluble aluminum compound, for example, as an inorganic salt, aluminum chloride or a hydrate thereof, aluminum sulfate or a hydrate thereof, ammonium alum and the like are known. Furthermore, a basic polyaluminum hydroxide compound which is an inorganic aluminum-containing cationic polymer is known and preferably used.

The basic polyaluminum hydroxide compound has a main component represented by the following general formula 1, 2, or 3, for example, [Al ₆ (OH) ₁₅ ] ³⁺ , [Al ₈ (OH) ₂₀ ] ⁴⁺ , [ It is a water-soluble polyaluminum hydroxide containing a basic and high-molecular polynuclear condensed ion stably such as Al ₁₃ (OH) ₃₄ ] ⁵⁺ , [Al ₂₁ (OH) ₆₀ ] ³⁺ , and the like.

[Al ₂ (OH) _n Cl _6-n ] _m General formula 1
[Al (OH) ₃ ] _n AlCl ₃ General formula 2
Al _n (OH) _m Cl _(3n-m) 0 <m <3n General formula 3

  These are water treatment agents from Taki Chemical Co., Ltd. under the name of polyaluminum chloride (PAC), from Asada Chemical Co., Ltd. under the name of polyaluminum hydroxide (Paho), and from Riken Green Co., Ltd. It is marketed under the name of Purachem WT and from other manufacturers for the same purpose, and various grades can be easily obtained.

  As the water-soluble compound containing a Group 4A element of the periodic table used in the present invention, a water-soluble compound containing titanium or zirconium is more preferable. Examples of the water-soluble compound containing titanium include titanium chloride and titanium sulfate. Water-soluble compounds containing zirconium include zirconium acetate, zirconium chloride, zirconium oxychloride, hydroxy zirconium chloride, zirconium nitrate, basic zirconium carbonate, zirconium hydroxide, zirconium lactate, zirconium carbonate / ammonium, zirconium carbonate / potassium, zirconium sulfate. And zirconium fluoride compounds. In the present invention, the term “water-soluble” means that 1% by mass or more dissolves in water at room temperature and normal pressure.

  As is well known, when these atomized silicas are used in the ink receiving layer, the surface gloss and the color development (optical density value) of the printed part are improved, but the long fiber length which is a problem in the present invention is long. When it is coated on the support, the texture of the support is excessively emphasized and the surface becomes uncomfortable. In addition, when printed with pigment ink, the printed portion, particularly the dark-colored printed portion, becomes more glossy due to the influence of the polymer component in the ink, resulting in a non-uniform image in which only the printed portion is glaring. End up. Although it is a well-known method to adjust the surface gloss by adding a matting agent to these problems, the addition of the matting agent has the effect of reducing the surface gloss, but at the same time reduces the color development. This is not preferable. The cause of this color reduction is that the addition of the matting agent promotes the sinking of the ink color material into the receiving layer, the haze value of the receiving layer itself increases, and the sinking ink color material contributes to the color development. This is thought to be caused by the fact that it becomes smaller. For these reasons, it has been difficult to obtain an ink jet recording sheet that is excellent in color development on a support having a long fiber length and that has little glare on the printed portion.

  The inventors of the present invention have found that an effect of suppressing glare in the printed portion of the pigment ink can be obtained while maintaining color development by using a matting agent that has been cationized when adjusting the surface gloss. By performing the cationization treatment on the matting agent added for the purpose of adjusting the gloss, the fixing property of the coloring material can be further improved. As the matting agent used in the present invention, a known matting agent can be used regardless of whether it is organic or inorganic. Examples of the organic matting agent include polymer particles such as a polymer ester of acrylic acid or methacrylic acid, such as poly (methyl methacrylate), styrene polymer and copolymer. Examples of the inorganic matting agent include glass, silicon dioxide, titanium dioxide, magnesium oxide, aluminum oxide, barium sulfate, calcium carbonate and the like. There is no particular limitation on the shape of the matting agent.

  As for the cationization treatment of the matting agent, the method described in the above-mentioned cationization of pulverized silica can be used as it is, and it can also be carried out by other physical and chemical modification methods. The form of the matting agent preferably used in the present invention is to use the same silica as the pulverized silica forming the ink receiving layer in an unground or appropriately pulverized state. Furthermore, the matting agent cationization treatment method is more preferably the same as the pulverized silica cationization treatment method constituting the ink receiving layer. By doing so, defects are less likely to occur when the ink receiving layer is applied, and unevenness in ink absorbability and fixability is less likely to occur when printed. The average particle size of the matting agent advantageously used in the present invention is preferably 1 μm or more and 20 μm or less, and more preferably 2 μm or more and 15 μm or less. Further, the amount of the matting agent to be added varies somewhat depending on the type and particle size of the matting agent to be used, but is preferably 0.1 to 20% by mass with respect to the total solid content mass of the added ink image receiving layer. 5-15 mass% is further more preferable.

  In the present invention, an inkjet recording material is obtained by applying an inorganic pigment dispersion liquid finely pulverized by the above method and a coating liquid containing a matting agent and a resin binder on a support and drying them. Various known binders can be used as the resin binder, and a hydrophilic binder is preferably used from the viewpoint of transparency and ink permeability. In using the hydrophilic binder, it is important that the hydrophilic binder does not swell during the initial penetration of the ink and block the voids. From this viewpoint, a hydrophilic binder having a relatively low swellability around room temperature is preferable. Used. Particularly preferred hydrophilic binders are fully or partially saponified polyvinyl alcohol or cation-modified polyvinyl alcohol.

  Particularly preferred among polyvinyl alcohols are partially saponified products or fully saponified products having a saponification degree of 80% or more. Those having an average degree of polymerization of 200 to 5000 are preferred.

  Examples of the cation-modified polyvinyl alcohol include polyvinyl alcohol having a primary to tertiary amino group or a quaternary ammonium group in the main chain or side chain of polyvinyl alcohol as described in JP-A-61-110483. It is.

  The smaller the polyvinyl alcohol content, the better the void volume in the ink receiving layer and the higher the ink absorbability.However, if the amount is too small, the ink receiving layer becomes brittle and surface defects such as cracks occur, Since it becomes a cause of a fall, the range of 5-40 mass% is preferable with respect to a silica fine particle, and 10-30 mass% is especially preferable.

  In the present invention, a cross-linking agent (hardener) for the resin binder may be used. Specific examples of the crosslinking agent include aldehyde compounds such as formaldehyde and glutaraldehyde, ketone compounds such as diacetyl and chloropentanedione, bis (2-chloroethylurea), 2-hydroxy-4,6-dichloro-1, 3,5-triazine, a compound having a reactive halogen as described in US Pat. No. 3,288,775, divinyl sulfone, a compound having a reactive olefin as described in US Pat. No. 3,635,718, N-methylol compounds as described in Japanese Patent No. 2,732,316, isocyanates as described in US Pat. No. 3,103,437, US Pat. Nos. 3,017,280 and 2,983,611 described Aziridine compounds such as US Pat. No. 3,100,704, carbodiimide compounds, US Epoxy compounds such as those described in allowed 3,091,537, halogen carboxaldehydes such as mucochloric acid, dioxane derivatives such as dihydroxydioxane, chromium alum, zirconium sulfate, boric acid, borate, inorganic cross-linking agents such as borax, etc. These can be used alone or in combination of two or more. Among these, boric acid, borax or borate is particularly preferable. In the case of adding a hardener, the effective amount of the hardener added is preferably 0.02 to 50 mass%, particularly preferably 0.5 to 35 mass%, based on the resin binder.

  In the present invention, a cationic compound may be further added for the purpose of improving the water resistance of the ink jet recording material. Examples of the cationic compound include the cationic polymer mentioned in the description of the pulverization of amorphous silica and the water-soluble metal compound. In particular, a compound composed of a cationic polymer having a molecular weight of about 5,000 to 100,000 and aluminum or a group 4A metal (for example, zirconium or titanium) in the periodic table is preferable. One type of cationic compound may be used, or a plurality of compounds may be used in combination.

  A surfactant can be added to the ink receiving layer of the present invention. The surfactant used may be any of anionic, cationic, nonionic, and betaine types, and may be of low or high molecular weight, and two or more surfactants may be used in combination. Also good.

  In addition to the at least one ink receiving layer, the ink jet recording material of the present invention may be provided with a layer having another function such as an ink absorbing layer having a different structure or a protective layer.

  In the present invention, the ink receiving layer of each layer further comprises a coloring dye, a coloring pigment, an ink dye fixing agent, an ultraviolet absorber, an antioxidant, a pigment dispersant, an antifoaming agent, a leveling agent, an antiseptic, a fluorescent enhancement agent. Various known additives such as a whitening agent, a viscosity stabilizer, a pH adjusting agent, a silane, or a titanium coupling agent can also be added.

  In the present invention, a known coating method can be used as a coating method of each layer constituting the ink receiving layer. For example, there are a slide bead method, a curtain method, an extrusion method, an air knife method, a roll coating method, a Ked bar coating method, and the like.

The dry coating amount of the ink receiving layer of the present invention is 5 to 30 g / m ² , particularly 10 to ²⁰ g / m ² as the solid content of the inorganic fine particles in terms of ink absorbability, ink receiving layer strength, and productivity. A range of m ² is preferred.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, the content of this invention is not restricted to an Example. In addition, a part and% show a mass part and the mass%.

<Silica dispersion 1>
While stirring a dispersion medium in which 0.25 parts of barium chloride dihydrate and 4 parts of dimethyldiallylammonium chloride homopolymer (molecular weight 9,000) were previously dissolved in water with a biaxial dissolver (circumferential speed 10 m / s) 100 parts of precipitated silica (Nipseal LP manufactured by Tosoh Silica Co., Ltd .; oil absorption 200 ml / 100 g, average primary particle size 15 nm) was gradually added to obtain a silica dispersion 1 having a silica concentration of 30% by mass. The average secondary particle diameter of silica of the obtained silica dispersion 1 was 15 μm.

<Silica dispersion 2>
Silica dispersion 1 was subjected to a bead mill (Nano Glen Mill manufactured by Asada Tekko Co., Ltd .; inner volume 20 l, 0.3 mm zirconia beads with an apparent bulk volume ratio of 76.5% filling) at a disk peripheral speed of 14 m / s and liquid flow rate of 6 l / s. The silica dispersion 2 was obtained by pulverizing under the operating conditions of 1 minute. The average secondary particle diameter of silica in the obtained silica dispersion 2 was 200 nm, and no particles of 1 μm or more were present.

<Recording sheet>
An ink receiving layer coating liquid prepared to have the following composition on cotton paper (Somerset enhanced velocity: 250 g / m ^2, manufactured by Inversk) having an average fiber length of 2.36 mm (measured by a Kajaani fiber length measuring device) The recording material for inkjet of Example 1 was produced by applying and drying with a wire bar so that the application amount was 20 g / m ² .

<Ink-receiving layer coating solution>
Silica dispersion 2 (as silica solid content) 100 parts Silica dispersion 1 (as silica solid content) 10 parts Polyvinyl alcohol 18 parts (degree of saponification 88%, average degree of polymerization 3500)
Solid content concentration of boric acid 4 parts coating solution 18% by mass

(Comparative Example 1)
An inkjet recording material of Comparative Example 1 was obtained in the same manner as in Example 1 except that the silica dispersion 2 of Example 1 was entirely replaced with the silica dispersion 1.

(Comparative Example 2)
An inkjet recording material of Comparative Example 2 was obtained in the same manner as in Example 1 except that all of the silica dispersion 1 of Example 1 was replaced with the silica dispersion 2.

(Comparative Example 3)
The inkjet recording material of Comparative Example 3 was obtained in the same manner as in Example 1 except that the silica dispersion 1 of Example 1 was replaced with the following silica dispersion 3.

<Silica dispersion 3>
Precipitated silica (Nipseal LP manufactured by Tosoh Silica Corp .; oil absorption 200 ml) while stirring 0.25 part of barium chloride dihydrate in water in a biaxial dissolver (circumferential speed 10 m / s) with strong stirring / 100 g, average primary particle size 15 nm) 100 parts were gradually added to prepare silica dispersion 3 having a silica concentration of 30% by mass. The average secondary particle diameter of silica in the obtained silica dispersion 3 was 15 μm.

  The following evaluation was performed about each obtained recording material for inkjets. The results are shown in Table 1.

<Gloss difference (with glare)>
Black solid printing was performed with a commercially available pigment ink printer (PX-5500 manufactured by Seiko Epson Corporation), and 60 ° gloss of the blank paper portion and the solid printing portion was measured with a handy gloss meter “Gloss Checker IG-330” (Horiba Seisakusho). The difference in gloss between the printed portion and the blank paper portion was evaluated according to the following criteria by measuring the difference between the measured values. The larger the value, the greater the difference in gloss and the stronger the glare of the image is observed.
○: Gloss difference is less than 10 ° Δ: Gloss difference is 10 ° or more and less than 15 ° ×: Gloss difference is 15 ° or more

<Color development>
Cyan, magenta, yellow, and black solid printing was performed with a commercially available pigment ink printer (Seiko Epson PX-5500), and color developability based on the following criteria from the total optical density of each color measured with a Macbeth reflection densitometer. Evaluated. The larger the value, the better the color developability.
◎: Total value is above 7.5 ○: Total value is 6.5 or more and less than 7.5 Δ: Total value is 5.5 or more and less than 6.5 ×: Total value is less than 5.5

  From the above results, it can be seen that the inkjet recording material obtained in Example 1 has a high color development and a small gloss difference between the printed portion and the blank paper portion. When the particle size of the pigment constituting the ink receiving layer is large as in Comparative Example 1, sinking of the ink coloring material into the medium occurs, and color development decreases. On the other hand, when the particle size of the pigment constituting the ink-receiving layer is reduced as in Comparative Example 2, the glare in the print portion is emphasized due to the gloss difference between the print portion and the blank paper portion, and only an uncomfortable image is displayed. I can't get it. Further, in order to prevent glare, simply adding a matting agent as in Comparative Example 3 significantly reduces the color development.

Claims (2)

  In an ink jet recording paper in which an ink receiving layer is provided on a support composed of pulp fibers having an average fiber length of 1 mm or more, the ink receiving layer is cationized with inorganic fine particles having an average secondary particle size of 500 nm or less An ink jet recording material comprising a matting agent.   2. The ink jet recording material according to claim 1, wherein the average particle size of the matting agent is 1 μm or more and 20 μm or less.