JP4466553B2 - Inkjet recording medium - Google Patents

Description

  The present invention relates to an ink jet recording material.

  The ink jet recording system that ejects water-based ink from fine nozzles toward the ink jet recording body and forms an image on the surface of the recording body has low noise during recording operation, easy formation of a full color image, high speed It is widely used in terminal printers, facsimiles, plotters, form printing, and the like due to the fact that recording is possible and the recording cost is lower than other printing apparatuses.

  In recent years, the rapid spread of printers and higher definition and higher speed have been accompanied, and along with this, inkjet recording media have been required to improve the ink absorption speed more than before. There is a strong demand for high uniformity of images comparable to silver salt photography. Further, in order to bring the quality of a recorded image closer to that of a photographic image, further improvement in the color density and glossiness of the recorded image is desired.

  In order to satisfy further improvement in the color density and glossiness of the recorded image, silica fine particles having an average primary particle diameter of 10 nm or less and a water-soluble resin are provided on an opaque support (so-called RC paper) provided with a polyolefin coating layer on the surface. An ink jet recording body in which a layer composed of the above is formed has been proposed (see, for example, Patent Document 1 and Patent Document 2). However, since polyolefin-coated paper is used, it becomes expensive, and an inexpensive paper-based ink jet recording material has been desired.

  On the other hand, an ink jet recording body in which an ink receiving layer having silica fine particles having an average particle diameter of 100 nm or less, a hydrophilic binder, and a hardener is formed on a water-absorbing support has been proposed (for example, see Patent Document 3). However, since the ink receiving layer is directly formed on the paper base material, there is a problem that cockling occurs during printing. In particular, when a paper substrate of less than 160 μm was used, this cockling problem was remarkable.

JP-A-8-174992 Japanese Patent Laid-Open No. 7-117334 JP-A-11-78214

  An object of the present invention is to provide an ink jet recording material using a paper base material as a support, and providing an ink jet recording material which is excellent in color density and glossiness of a recorded image and hardly causes cockling.

  As a result of intensive studies to solve such problems, the present inventors have not formed an ink receiving layer directly on a paper substrate, but at least one coating layer containing a pigment and a binder in advance. The inventors have found that this is achieved by specifying the 30 second value of the Cobb water absorption on the surface of the coating layer and further using the specific fine pigment for the ink receiving layer, and have reached the present invention.

The present invention includes the following embodiments.
[1] In an ink jet recording material having an ink receiving layer on a support, the support contains 5 to 50 parts by weight of a binder and 100 parts by weight of the pigment on the surface of the paper substrate. Having at least one coating layer (however, it does not have a water-resistant layer coated with 3 to 12 g / m ^{2 of} latex polymer having a glass transition temperature of −10 to 50 ° C. ) , and the coating a paper support 30 seconds value of the Cobb water absorption degree is 20.0 g / ^{m 2} or less as defined in JIS P8140 layer surface, the ink-receiving layer is formed on the coating coating layer of the support, and, gas It is a coating layer obtained by treating phase silica with a cationic compound and having a fine volume of BET pore volume of 0.5 ml / g or more and an average particle size of 700 nm or less and an adhesive as main components. An ink jet recording material characterized by the above.
[2] The ink jet recording material according to [1], wherein the pigment contained in the coating layer of the paper support contains as a main component one selected from kaolin, calcium carbonate, and satin white.
[3] The ink jet recording material according to [1] or [2], wherein the particle diameter of the pigment contained in the coating layer of the paper support is 0.2 μm or more and 10 μm or less.

  According to the present invention, it is possible to provide an ink jet recording material which can obtain high-quality recording and hardly cause cockling even in an ink jet recording material using a paper base material.

In the present invention, a coating layer containing a pigment and a binder is formed on a paper base material, and a layer in which the Cobb water absorption value on the surface of the coating layer is 30 g / m ² or less is formed. Using a paper support, an ink receiving layer mainly composed of a fine pigment and an adhesive having a BET pore volume of 0.5 ml / g or more and an average particle diameter of 700 nm or less is formed on the coating layer. .

  Normally, when a photographic image is inkjet-recorded on an A4 size inkjet recording body, it takes about 30 seconds from the end of the recording body receiving ink to the end of the recording body receiving ink. During this time, if the ink or the solvent constituting the ink penetrates the paper base material, the paper base material expands and contracts during output and cockling occurs. When cockling occurs at the time of recording, the surface of the recording body undulates, and troubles such as rubbing between the printer head and the recording body may occur.

In the present invention, such a cockling is formed by forming a coating layer on a paper substrate so that the 30 second value of the Cobb water absorption is 20 g / m ² or less, and forming an ink receiving layer thereon. It suppresses. Ink jet recording media using a conventional polyolefin-coated paper as a support do not cause ink or a solvent constituting the ink to penetrate into the support, and there is no problem of cockling. On the other hand, a mat type ink jet recording body using a paper support uses a pigment having a large particle diameter (about several microns) for the ink receiving layer, and therefore has a large ink absorption amount in the ink receiving layer. Even if the solvent constituting the ink penetrates into the paper base material, the recording speed is set to be high, and since recording that requires high image quality such as a photographic image is not performed, there is no big problem.

If the 30 second value of the Cobb water absorption on the coated layer surface of the paper support exceeds 20 g / m ² , cockling will remarkably occur. A preferable range of the Cobb water absorption is 18 g / m ² or less. The lower limit value is preferably closer to 0 g / m ² because the controllability of cockling is better, but it is more preferably 5 g / m ² or more in view of the coating suitability of the ink receiving layer.

  Such a paper support having a Cobb water absorbency is selected from the selection of the material constituting the paper substrate, the selection of the production method of the paper substrate, the selection of the material constituting the coating layer, and the production method of the coating layer. This can be achieved by appropriately adjusting the selection.

The paper base is generally composed mainly of wood pulp and a filler containing it if necessary.
As the wood pulp, various chemical pulps, mechanical pulps, regenerated pulps and the like can be used, and these pulps can be beaten by a beating machine in order to adjust paper strength, papermaking suitability, and the like. The beating degree (freeness) of the pulp is not particularly limited, but is generally about 250 to 550 ml (CSF: JIS P8121). In order to obtain the above-mentioned Cobb water absorption, the freeness is preferably adjusted to about 300 to 500 ml.

  The filler is blended for the purpose of imparting opacity and the like, and calcium carbonate, kaolin, talc, silica, titanium oxide and the like can be used as appropriate. In particular, calcium carbonate is preferable because it becomes a substrate with high whiteness and glossiness of the ink jet recording paper is enhanced. The content (ash) of the filler in the paper substrate is preferably about 1 to 30%, but if it is too much, the Cobb water absorption tends to increase or the paper strength tends to be weak, so the preferable content of the filler Is 5 to 20%. In addition, since calcined kaolin and silica are bulky and the Cobb water absorption is likely to be high, it is preferable to contain calcined kaolin at about 1 to 7% and silica at about 1 to 5%.

  A sizing agent, a fixing agent, a paper strength enhancer, a cationizing agent, a yield improving agent, a dye, a fluorescent brightening agent, and the like can be added to the paper base as an auxiliary agent. Furthermore, in the size press process of the paper machine, starch, polyvinyl alcohol, cationic resin, etc. can be applied and impregnated to adjust the surface strength, Cobb water absorption, and the like.

  As a pigment which forms a coating layer, the well-known pigment which can be used with the coating paper for printing etc. can be illustrated. Examples thereof include calcium carbonate, kaolin, calcined kaolin, clay, calcined clay, zinc oxide, aluminum hydroxide, satin white, magnesium silicate, magnesium carbonate, titanium dioxide, and plastic pigment. These can also use multiple types together. The particle diameter of the pigment is not particularly limited, but is 0.2 μm or more and 10 μm or less, preferably 0.5 μm or more and 5 μm or less. If the particle diameter is large, the surface of the coating layer becomes rough, the thickness of the ink receiving layer is not uniform, and unevenness tends to occur in the recorded matter, so that the image quality is impaired. When the particle diameter is small, the Cobb water absorption tends to increase. Among these pigments, calcium carbonate, kaolin, and satin white are particularly preferable because they have excellent suitability for suppressing cockling and become a coating layer with high whiteness. In addition, pigments rich in water absorption and fine pigments such as amorphous silica, colloidal silica, alumina, and zeolite, which are preferable materials for the ink receiving layer of the ink jet recording material, are used in combination within the specified Cobb water absorption range. May be.

  As the binder for forming the coating layer, known binders that can be used for coated paper for printing can be used. For example, water-soluble resins (for example, polyvinyl alcohol, cationic polyvinyl alcohol, silyl-modified polyvinyl alcohol, etc.) Polyvinyl alcohols such as modified polyvinyl alcohol, casein, soy protein, synthetic proteins, starch, cellulose derivatives such as carboxymethyl cellulose and methyl cellulose), or water-dispersible resins (for example, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer) Polymer, conjugated diene copolymer latex such as acrylonitrile-butadiene copolymer, acrylic copolymer, vinyl copolymer latex such as ethylene-vinyl acetate copolymer, styrene copolymer latex, (poly ) Various types of binders such as a latex polymer latex are used alone or in admixture of two or more. Among these, a water-dispersible resin is preferable because it has an excellent cockling suppressing effect, and an acrylic polymer latex and a (poly) urethane-based polymer emulsion are particularly preferably selected because they have a good storage stability over time. The Further, the glass transition temperature of the binder is not particularly limited, but a binder having a low glass transition temperature is preferable because it easily adjusts to the water absorption of the coating layer, and the glass transition temperature is about −25 to + 35 ° C. Can be preferably used.

  The blending ratio of the pigment and the binder is generally adjusted in the range of 3 to 50 parts by mass, preferably 5 to 40 parts by mass with respect to 100 parts by mass of the pigment, although it depends on the type. In addition, various auxiliary agents such as dispersants, thickeners, antifoaming agents, antistatic agents, preservatives, fluorescent dyes, colorants, and ultraviolet absorbers used in the production of general coated paper are added as appropriate.

  As a method for forming the coating layer, a coating solution containing the above components may be applied by a known coating method. For example, by various known coating devices such as blade coaters, air knife coaters, roll coaters, bar coaters, gravure coaters, rod blade coaters, lip coaters, curtain coaters, slide beads, slide hoppers, and die coaters such as slot dies. It is good to apply. In addition, a plurality of coating layers may be laminated, and in this case, the blending components of both coating layers may be different. Further, it may be formed by coating (so-called on-machine coating) with a coating apparatus installed in the paper machine.

The dry solids coating weight of the coating layer, without limitation, is preferably generally is 2 to 30 g / ^{m 2,} more preferably about a 4~25g / ^{m 2.} If the coating amount is too small, ink or the solvent constituting the ink permeates through the ink receiving layer and the coating layer and reaches the paper substrate when ink jet recording is performed on the paper substrate, thereby generating cockling. If the coating amount is too large, the effect of suppressing cockling is saturated, and the ink receiving layer tends to crack.

In the range satisfying the above-mentioned Cobb water absorption, the coating layer may be subjected to a smoothing process on the surface of the coating layer with a super calender or a calendar, or the surface of the coating layer may be roughened using a roughening roll. The surface may be molded using an embossing roll.
Since the ink receiving layer of the present invention is formed using a specific fine pigment, the texture of the surface of the coating layer may be the texture of the recording surface of the ink jet recording material.
In particular, the coating layer surface is J.P. TAPPI No. If the Oken smoothness specified by the 5b method is 300 seconds or more, a uniform ink-receiving layer can be formed, and an ink jet recording material with excellent image quality can be obtained.

  The back side of the paper support (the side on which the coating layer and ink receiving layer are not formed) is provided with a coat layer and a laminate layer to correct the curl to the front side. Polyolefin to give a silver salt photograph texture It is preferable to provide a back surface layer such as a resin laminate layer. Further, the back surface may be further treated with an antistatic agent, an antiblocking agent or the like for a transportability improving process, an antistatic process, or an antiblocking process. Although the back surface can be treated before or after forming the ink receiving layer, it is preferable to treat the back surface before forming the ink receiving layer because the ink receiving layer is less likely to be damaged.

  The ink receiving layer contains, as main components, a fine pigment and an adhesive having a pore volume by BET method of 0.5 ml / g or more and an average particle diameter of 700 nm or less. Here, the main component is sufficient if the total mass of the fine pigment and the adhesive is 50% by mass or more of the total mass of the ink receiving layer. In particular, it is preferably 80% by mass or more, more preferably 90% by mass or more, based on the total mass of the ink receiving layer.

  When a pigment having an average particle diameter larger than 700 nm is used, the printing density is lowered. In order to adjust the particle diameter to 700 nm or less, it can be produced by, for example, a method of applying a strong force by mechanical means, that is, a so-called breaking down method (a method of subdividing a bulk material). Mechanical means include: ultrasonic homogenizer, pressure homogenizer, liquid collision homogenizer, high-speed rotary mill, roller mill, container drive medium mill, medium agitator mill, jet mill, mortar, disintegrator A device for grinding and kneading the pulverized product with a bowl-shaped stirring bar), a sand grinder, a nanomizer and the like. In order to reduce the particle size, classification and pulverization can be repeated. On the other hand, if the average particle size is smaller than 10 nm, cracks are likely to occur in the coating film, and therefore it is preferably 10 nm to 700 nm. More preferably, it is 30 nm-500 nm.

  Further, if the pore volume by the BET method is smaller than 0.5 ml / g, the ink absorbability is insufficient. A more preferred pore volume is 0.8 ml / g or more, and a particularly preferred pore volume is 1.0 to 1.2 ml / g.

  As such a fine pigment, a fine pigment which is a dispersion of secondary particles formed by agglomerating primary particles having an average primary particle diameter of 3 nm to 40 nm is preferable, and amorphous silica, alumina, and alumina hydrate are preferable. It is. Of these, amorphous silica produced by a vapor phase method is most preferably used from the viewpoint of the film formability of the coating layer and the image density after printing.

  Amorphous silica is generally roughly classified into wet silica and dry (gas phase) silica depending on the production method. In the wet method, active silica is produced by acid decomposition of silicate, and this is a method in which this is appropriately polymerized and agglomerated and precipitated to obtain hydrous silica. Gel method silica, precipitation method silica, colloidal silica, etc. Belong to these. On the other hand, the gas phase method is a method by high-temperature gas phase hydrolysis of silicon halide (flame hydrolysis method), a method in which silica sand and coke are heated and reduced by an arc in an electric furnace and oxidized with air. The method of obtaining anhydrous silica by the (arc method) is the mainstream, and the gas phase method silica means anhydrous silica fine particles obtained by the gas phase method.

Vapor phase silica is different from wet silica in surface silanol group density and pore volume, and exhibits different properties. In the case of wet silica, the density of silanol groups on the fine particle surface is high at 5 to 8 / nm ² , and the silica fine particles tend to aggregate (aggregate) easily, so the pore volume when the pore diameter is 100 nm or less is low. However, in the case of vapor phase method silica, the density of silanol groups on the surface of the fine particles is as small as ² to 3 / nm ² , so that loose soft agglomeration (flocculate) occurs and the pore volume increases, As a result, a three-dimensional structure with a high porosity is formed.

  Alumina is generally called aluminum oxide having crystallinity. Generally, alumina having χ, κ, γ, δ, θ, η, ρ, pseudo γ, and α crystals can be mentioned. From the viewpoint of glossiness and ink absorbability, vapor-phase method alumina and alumina having γ, δ, and θ crystals are preferably selected. Vapor phase alumina (fumed alumina) having a sharp particle size distribution and particularly excellent film formability is particularly preferred. Vapor phase alumina is formed by high temperature hydrolysis of gaseous aluminum trichloride.

  The alumina hydrate is not particularly limited, but boehmite or pseudoboehmite is preferably selected from the viewpoints of ink absorbability and film formability. The production method of alumina hydrate includes, for example, a method of hydrolyzing aluminum isopropoxide with water (BE Yoldas, Amer. Ceram. Soc. Bull., 54, 289 (1975), etc.) and aluminum alkoxide. (Japanese Patent Laid-Open No. 06-064918) and the like.

As a binder for the ink receiving layer, water-soluble resins (for example, polyvinyl alcohols such as polyvinyl alcohol, cationic polyvinyl alcohol, modified polyvinyl alcohol such as silyl-modified polyvinyl alcohol, casein, soy protein, synthetic proteins, starch, carboxymethyl cellulose, Cellulose derivatives such as methylcellulose) or water-dispersible resins (for example, conjugated diene polymer latex such as styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, acrylonitrile-butadiene copolymer, acrylic copolymer, Various binders such as vinyl copolymer latex such as ethylene-vinyl acetate copolymer, styrene copolymer latex, (poly) urethane polymer latex, etc.) are used alone. Or a mixture of two or more.
Among these, polyvinyl alcohol is preferable for improving the balance between film formability and ink absorbability, more preferably having a polymerization degree of 2000 or more, and polyvinyl alcohol having a polymerization degree of 3600 to 5000 is particularly preferable.
In this case, the dry solid content mass ratio of the fine pigment and the adhesive in the ink receiving layer is preferably in the range of 5 to 30 parts by mass with respect to 100 parts by mass of the pigment. In order to further improve the balance between ink absorbency and coating strength, the content is preferably 10 to 25 parts by mass.

Since the ink receiving layer contains fine pigments, cracks are likely to occur during coating. For this reason, a crack can be prevented using a crosslinking agent. The cross-linking agent may be blended in the coating liquid for the ink receiving layer, and may be added after the ink receiving layer is formed. Before applying the ink receiving layer, the coating liquid having the cross-linking agent may be added. You may apply | coat and may mix | blend with the coating layer of a paper support body.
As the crosslinking agent, known materials can be used as appropriate. When polyvinyl alcohol is taken as an example, examples of the crosslinking agent include boron compounds, epoxy compounds, glycidyl compounds, zirconium compounds, aluminum compounds, chromium compounds, and the like. Boron compounds are particularly preferred because the coating thickens or gels quickly.
The boron compound is an oxygen acid having a boron atom as a central atom and a salt thereof. Examples include orthoboric acid, metaboric acid, hypoboric acid, tetraboric acid, pentaboric acid, and their sodium, potassium, and ammonium salts. Among these, orthoboric acid and disodium tetraborate are preferably used because they have an effect of moderately thickening the paint.

The content of the boron compound is preferably 2 to 10% by mass based on the total mass of the ink receiving layer, although it depends on the type of boron compound and the degree of polymerization of polyvinyl alcohol. When it is less than 2% by mass, the crosslinking with polyvinyl alcohol is weak, the gelation of the coating is weakened, and the coating film is easily cracked. Moreover, when it exceeds 10 mass%, a coating film becomes hard and is unpreferable.
In addition, although polyvinyl alcohol was made into the representative example, this invention is not limited to polyvinyl alcohol.

The ink receiving layer preferably contains a cationic compound in order to improve the water resistance and storage stability of the recorded image. As a cationic compound, a polyalkyleneamine compound (for example, polyethylene polyamine, polypropylene polyamine) forms an acrylic resin having a secondary, tertiary amino group, or quaternary ammonium group, polyvinylamine, polyvinylamidine, and a 5-membered ring. amidine compounds you are, dicyan cationic resins (e.g., dicyandiamide - formaldehyde polycondensate), epichlorohydrin - dimethylamine addition polymer, dimethyl diallyl ammonium chloride -SO ₂ copolymer, diallylamine -SO ₂ copolymer, dimethyl diallyl Cationic polymers such as ammonium chloride polymer, allylamine salt polymer, dialkylaminoethyl (meth) acrylate ammonium salt polymer, acrylamide-diallylamine salt copolymer; Cationic coupling agents such as zinc, titanate, aluminum or zirconium; water-soluble aluminum compounds (for example, aluminum chloride or hydrates thereof, aluminum sulfate or hydrates, inorganic salts such as ammonium alum, inorganic Polyaluminum hydroxide compounds that are aluminum-containing cationic polymers, water-soluble zirconium compounds (eg, zirconium acetate, zirconium chloride, zirconium oxychloride, zirconium zirconium chloride, zirconium nitrate, basic zirconium carbonate, zirconium hydroxide, carbonic acid) Zirconium / ammonium, zirconium carbonate / potassium, zirconium sulfate, zirconium fluoride compounds, etc.), water-soluble titanium compounds (eg, titanium chloride, titanium sulfate, etc.), water-soluble lanthanoids Cationic substances such as water-soluble polyvalent metal salts such as compounds (for example, cerium chloride, cerium nitrate, cerium sulfate, cerium acetate, lanthanum nitrate, etc.) can be exemplified, and these can be used alone or in combination.
In addition, it is preferable to use a cationic polymer having a molecular weight of 5000 or more because if the molecular weight is lower than 5000, the ink absorbability may be hindered. As the coupling agent, a silane coupling agent having an ammonium group is preferable. As the water-soluble polyvalent metal salt, aluminum compounds such as polyaluminum chloride, polyaluminum acetate and polyaluminum lactate, and zirconium compounds such as zirconium acetate, zirconium chloride, chlorinated zirconium oxide octahydrate and hydroxyzirconium chloride are preferable.

  In general, in the case of silica, since silanol groups are present on the surface, it is electrically negative and aggregates when mixed with a cationic compound. For this reason, when silica is used in the form of composite particles treated with a cationic compound, it has excellent dispersibility, printing density, image water resistance, and the like, and an excellent quality comparable to silver salt photography can be obtained.

  As a method for treating silica with a cationic compound, a known method can be employed. For example, a method of coating a silica surface by reacting a compound of polyvalent metal ions such as aluminum ions such as polyaluminum chloride, polyaluminum acetate, and polyaluminum salts such as polyaluminum lactate, silane having an ammonium group A method in which a coupling agent is added to the surface of silica for modification, and a cationic polymer-silica aggregate particle obtained by mixing and aggregating silica and a cationic polymer is pulverized and dispersed to form a cation. Examples thereof include a method for producing a functional polymer-silica composite particle.

In order to disperse or pulverize a mixture or aggregate of the silica and the cationic compound, a homomixer, a pressure homogenizer, an ultrasonic homogenizer, a microfluidizer, an optimizer, a nanomizer, a high-speed rotary mill, a roller mill, a container drive medium A mill, a medium stirring mill, a jet mill, a sand grinder, a Clare mix, or the like is used.
When the average particle diameter exceeds 1 μm, it is sufficiently dispersed if treated with a weak mechanical force such as a homomixer, but it is effective to apply a stronger mechanical force to pulverize the average particle diameter to 1 μm or less, It is preferable to use a pressure type dispersion method. Examples of the high-pressure pulverizer that is a pressure dispersion method include a pressure homogenizer, an ultrasonic homogenizer, a microfluidizer, and a nanomizer. Particularly, a microfluidizer and a nanomizer are preferable as a high-speed flow collision type homogenizer.

The dry solids coating weight of the ink receiving layer, but is not limited, it is preferable that generally is 5 to 30 g / ^{m 2,} more preferably about a 7~25g / ^{m 2.} If the coating amount is too small, the high-definition and high-speed printer may have insufficient ink absorbability. If the coating amount is too large, it may be difficult to control cracks in the coating film.
The ink receiving layer may be a single layer or a multilayer. In the case of multiple layers, the composition may be different for each layer.
For coating the ink receiving layer, use various coating devices such as blade coater, air knife coater, roll coater, bar coater, gravure coater, rod blade coater, lip coater, curtain coater, die coater, and slide bead coater. Can do.

  A glossy expression layer having a colloidal substance such as glass beads, colloidal silica, colloidal alumina, etc. may be formed on the ink receiving layer. Alternatively, a surface layer containing fine particles having a high refractive index such as titanium oxide, zinc oxide, zirconium oxide, cerium oxide, ferric trioxide, and antimony oxide may be formed. In this case, these fine particles are made of silica or alumina. The surface may be coated.

The average particle diameter of the pigment referred to in the present invention is the secondary particle diameter when primary particles are aggregated to form secondary particles, and the primary particle diameter when monodispersed with only primary particles. Regardless of whether the pigment is in the form of a powder or a slurry.
The measurement method was as follows: 200 g of an aqueous dispersion having a pigment concentration of 3% by mass was prepared, and this was subjected to a stirring and dispersing treatment at 1000 rpm for 30 minutes using a homomixer, and immediately thereafter the dispersion was subjected to an electron microscope (SEM and TEM ) For observation, take an electron microscope photograph of 10,000 to 400,000 times, and measure and average the martin diameter of particles present in an area of 5 cm × 5 cm square in the photograph. (See "Particle Handbook", Asakura Shoten, p52, 1991).

(Method of measuring pore volume by BET)
The inorganic pigment or the dispersion of the inorganic pigment was dried at 105 ° C. to obtain a powder sample for measurement. The pore volume of this powder sample was measured after vacuum degassing at 200 ° C. for 2 hours as a pretreatment using a nitrogen gas adsorption specific surface area / pore distribution measuring apparatus (SA3100 plus type manufactured by Coulter). As the pore volume, the value of the total pore volume (nitrogen relative pressure 0.991) having a pore diameter of 3 to 200 nm was used.

  The present invention will be described more specifically with reference to the following examples, but the technical scope of the present invention is not limited thereto. First, materials used in Examples and Comparative Examples will be described.

Example 1
[Manufacture of paper support]
“Forming paper substrates”
To a pulp slurry consisting of 90 parts of LBKP (freeness 440 ml / csf) and 10 parts of NBKP (freeness 510 ml / csf), light calcium carbonate as a filler is added to the pulp solids so as to be 10% in terms of paper ash content. As an additive sizing agent, AKD sizing agent (trade name: Size Pine K-902, manufactured by Arakawa Chemical Industries, Ltd.) 0.05% and aluminum sulfate 0.5% were respectively added to prepare a paper stock. Using the stock thus prepared, paper was made and dried with a hybrid type twin wire paper machine to obtain a paper (base paper). Next, an oxidized starch paste (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.) with a concentration of 6% is applied to both sides of the base paper thus obtained through a two-roll size press device in terms of double-sided solid content. It was applied and dried so as to be 1.4 g / m ² to obtain a paper base having a rice basis weight of 75 g / m ² .

“Preparation of coating solution for first coating layer”
As a pigment, acrylonitrile is used as a monomer ratio in a pigment slurry composed of 100% by mass of heavy calcium carbonate having an average particle size of 0.8 μm (trade name: Hydrocurve 90, manufactured by Bihoku Powder Chemical Co., Ltd.) with respect to 100 parts by mass of the pigment. 8 parts of styrene-butadiene copolymer latex (trade name: T-2629M, manufactured by JSR) having an average particle diameter of 125 nm, oxidized starch paste (trade name: Ace B, Oji Corn Starch) 1 part (all in terms of solid content) and auxiliary agents such as an antifoaming agent and a dye were added to finally prepare a coating solution having a solid content concentration of 64%.

“Preparation of coating solution for second coating layer”
Heavy calcium carbonate with an average particle size of 0.8 μm (trade name: Hydrocurve 90, manufactured by Bihoku Flour & Chemical Co., Ltd.) and fine kaolin with an average particle size of 0.3 μm (trade name: Milagros, manufactured by Engelhard): (US) A pigment consisting of 60% by mass was dispersed in water with a Coreless disperser to obtain a pigment slurry. A styrene-butadiene copolymer latex containing 21% by mass of acrylonitrile as a monomer ratio and having an average particle size of 95 nm (trade name: PA2323, manufactured by Nippon A & L Co., Ltd.) 11 with respect to 100 parts by mass of the pigment in the pigment slurry. Parts, oxidized starch paste (trade name: Ace B, manufactured by Oji Cornstarch Co., Ltd.), 3 parts (all in terms of solid content) and auxiliary agents such as antifoaming agents and dyes are added. A 64% coating solution was prepared.

"Formation of coating layer"
On both sides of the paper substrate, the first coating layer coating solution is applied and dried on each side using a blade coater so that the dry weight per side is 10 g / m ^2. The first coating layer was provided. Next, the coating liquid for the second coating layer was coated on each side with a blade coater and dried so that the dry weight per side was 10 g / m ^2. A coated paper was obtained. The coated paper thus obtained was passed through a super calender (10 nip, linear pressure 250 kg / cm, 400 m / min) to obtain a paper support.

[Manufacture of inkjet recording medium]
"Preparation of silica fine particle dispersion"
Gas phase method silica having an average particle diameter of 1.0 μm (manufactured by Nippon Aerosil Co., Ltd., trade name: Aerosil A300, average primary particle diameter: about 8 nm) was dispersed by a homomixer, and then the average secondary particle diameter was 800 nm. A 10% by mass silica fine particle dispersion was prepared by pulverizing and dispersing with a high-speed collision type homogenizer.

"Treatment with cationic compounds"
10 parts by mass of a cationic compound having a 5-membered ring amidine structure (product name: SC-700M, molecular weight: 30,000) having a 5-membered ring amidine structure is added to 100 parts by mass of this silica fine particle dispersion, and a high-speed flow collision type homogenizer is added. Was further dispersed to prepare a 10% by mass cationic polymer-silica composite particle dispersion having an average secondary particle size of 0.15 μm. The pore volume of this composite particle by BET was 1.1 ml / g.

"Preparation of coating solution for ink receiving layer"
As a fine pigment, 100 parts by weight (solid content) of the above cationic polymer-silica composite particle dispersion, 18 parts by weight of polyvinyl alcohol having a polymerization degree of 3500 and a saponification degree of 88.5% as a binder, and a dispersant (Toa Gosei) An aqueous dispersion (concentration: 15% by mass) was prepared by mixing 0.05 part by mass, trade name: Aron SD-10) manufactured by the company.

"Formation of ink-receiving layer"
After applying an 8% borax aqueous solution to the coating layer surface of the paper support, the coating liquid for the ink-receiving layer having the above composition was applied to hydrogel, and then the hydrogelated coating solution layer was The ink-jet recording material was produced by drying with a dryer. The dry coating amount of the ink receiving layer was 22 g / m ² .
The Cobb water absorption (30 second value) of the surface of the paper support on which the ink receiving layer was applied was 19.4 g / m ² and the Oken smoothness was 908 seconds.

Comparative Example 1
[Manufacture of paper support]
“Forming paper substrates”
A paper substrate was obtained in the same manner as in Example 1.

“Preparation of coating solution for first coating layer”
In the same manner as in Example 1, a first coating layer coating solution was prepared.

“Preparation of coating solution for second coating layer”
30% by mass of light calcium carbonate having an average particle size of 2 μm (trade name: Tama Pearl 121, manufactured by Okutama Kogyo Co., Ltd.) and fine kaolin having an average particle size of 0.3 μm (trade name: Milagros, manufactured by Engelhard Inc .: USA) The coating liquid for 2nd coating layers was prepared like Example 1 except having changed from 60 mass% to 30 mass%.

"Formation of coating layer"
On both sides of the paper substrate, the first coating layer coating solution is applied and dried on each side using a blade coater so that the dry weight per side is 10 g / m ^2. The first coating layer was provided. Next, the coating liquid for the second coating layer was coated on each side with a blade coater and dried so that the dry weight per side was 10 g / m ^2. Coating was performed, and the coated paper thus obtained was passed through a super calender (4 nips, linear pressure 100 kg / cm, 400 m / min) to obtain a paper support.

[Manufacture of inkjet recording medium]
An ink receiving layer was formed in the same manner as in Example 1 using the obtained paper support.
The Cobb water absorption (30 seconds value) of the surface of the paper support on which the ink receiving layer was applied was 22.1 g / m ² and the Oken type smoothness was 137 seconds.

Example 2
[Manufacture of paper support]
“Forming paper substrates”
A paper substrate was obtained in the same manner as in Example 1 except that the basis weight was 135 g / m ² .

“Preparation of coating solution for first coating layer”
In the same manner as in Example 1, a first coating layer coating solution was prepared.

“Preparation of coating solution for second coating layer”
Heavy calcium carbonate with an average particle size of 0.8 μm (trade name: Hydrocurve 90, manufactured by Bihoku Powder Chemical Co., Ltd.) 10 mass%, light calcium carbonate with an average particle size of 2 μm (product name: Tama Pearl 121, manufactured by Okutama Kogyo Co., Ltd.) 10% by mass), and a pigment slurry comprising 80% by mass of fine kaolin (trade name: Milagros, manufactured by Engelhard Inc .: USA) with an average particle size of 0.3 μm is dispersed in water using a Coreless disperser to obtain a pigment slurry. It was. A styrene-butadiene copolymer latex containing 21% by mass of acrylonitrile as a monomer ratio and having an average particle size of 95 nm (trade name: PA2323, manufactured by Nippon A & L Co., Ltd.) 11 with respect to 100 parts by mass of the pigment in the pigment slurry. Parts, oxidized starch paste (trade name: Ace B, manufactured by Oji Cornstarch Co., Ltd.), (both solid content conversion) and auxiliary agents such as antifoaming agents and dyes are added, and finally the solid content concentration A 64% coating solution was prepared.

"Formation of coating layer"
On both sides of the paper substrate, the first coating layer coating solution is applied and dried on each side using a blade coater so that the dry weight per side is 12 g / m ^2. The first coating layer was provided. Next, the coating liquid for the second coating layer was applied on a single side with a blade coater so that the dry weight per side was 12 g / m ^2, and dried by applying twice to one side with a moisture content of 5.0%. A coated paper was obtained. The coated paper thus obtained was passed through a super calender (10 nip, linear pressure 250 kg / cm, 400 m / min) to obtain a paper support.

[Manufacture of inkjet recording medium]
An ink receiving layer was formed in the same manner as in Example 1 using the obtained paper support.
The Cobb water absorption (30 second value) of the surface of the paper support on which the ink receiving layer was applied was 17.5 g / m ² , and the Oken smoothness was 1320 seconds.

Example 3
[Manufacture of paper support]
“Forming paper substrates”
A paper substrate was obtained in the same manner as in Example 1 except that the basis weight was 135 g / m ² .

“Preparation of coating solution for first coating layer”
In the same manner as in Example 1, a first coating layer coating solution was prepared.

“Preparation of coating solution for second coating layer”
Heavy calcium carbonate with an average particle size of 0.8 μm (trade name: Hydrocurve 90, manufactured by Bihoku Powder Chemical Co., Ltd.) 40 mass%, light calcium carbonate with an average particle size of 2 μm (product name: Tama Pearl 121, manufactured by Okutama Kogyo Co., Ltd.) ) 10% by weight of fine kaolin (trade name: Milagros, manufactured by Engelhard Inc .: USA) having an average particle size of 0.3 μm and Kaolin (trade name: Ultra White 90, Engelhard) having an average particle size of 0.6 μm A pigment slurry was obtained by dispersing 20% by mass of a pigment in water using a Coreless disperser. A styrene-butadiene copolymer latex containing 21% by mass of acrylonitrile as a monomer ratio and having an average particle size of 95 nm (trade name: PA2323, manufactured by Nippon A & L Co., Ltd.) 10 with respect to 100 parts by mass of the pigment. Parts, oxidized starch paste (trade name: Ace B, manufactured by Oji Cornstarch Co., Ltd.), 3 parts (all in terms of solid content) and auxiliary agents such as antifoaming agents and dyes are added. A 64% coating solution was prepared.

"Formation of coating layer"
On both sides of the paper substrate, the first coating layer coating solution is applied and dried on each side using a blade coater so that the dry weight per side is 12 g / m ^2. The first coating layer was provided. Next, the coating liquid for the second coating layer was applied on a single side with a blade coater so that the dry weight per side was 12 g / m ^2, and dried by applying twice to one side with a moisture content of 5.0%. A coated paper was obtained. The coated paper obtained in this way is subjected to a roughening calendar formed by combining three rolls of an elastic roll, a hard roughening roll (Rmax: 10 μm), and an elastic roll from the top. The paper support was obtained by passing the paper twice so that the other surface was in pressure contact with the elastic roll twice.

[Manufacture of inkjet recording medium]
An ink receiving layer was formed in the same manner as in Example 1 using the obtained paper support.
The surface of the paper support on which the ink receiving layer is applied is a surface treated with a roughening roll, and the Cobb water absorption (30 second value) is 15.5 g / m ^2. The degree was 290 seconds.

Comparative Example 2
[Manufacture of paper support]
“Forming paper substrates”
A paper base material was obtained in the same manner as in Example 1 except that the basis weight was 150 g / m ² .

“Preparation of coating solution for first coating layer”
In the same manner as in Example 1, a first coating layer coating solution was prepared.

“Preparation of coating solution for second coating layer”
In the same manner as in Example 1, a second coating layer coating solution was prepared.

"Formation of coating layer"
In the same manner as in Example 1, a coating layer was formed to obtain a paper support.

[Manufacture of inkjet recording medium]
An ink receiving layer was formed in the same manner as in Example 1 using the obtained paper support.
The Cobb water absorption (30 seconds value) of the surface of the paper support on which the ink receiving layer was applied was 23.4 g / m ² , and the Oken smoothness was 830 seconds.

Comparative Example 3
[Manufacture of paper support]
A paper support was obtained in the same manner as in Example 1.

[Manufacture of inkjet recording medium]
"Preparation of silica fine particle dispersion"
(A) Preparation of Active Silicic Acid Aqueous Solution Distilled water is added to a sodium silicate solution (trade name: No. 3 sodium silicate, manufactured by Tokuyama Co., Ltd.) having a SiO ₂ concentration of 30% by mass and a SiO ₂ / Na ₂ O molar ratio of 3.1. By mixing, a dilute sodium silicate aqueous solution having a SiO ₂ concentration of 4.0% by mass was prepared. This aqueous solution was passed through a column packed with a hydrogen-type cation exchange resin (manufactured by Mitsubishi Chemical Corporation, trade name: Diaion SK-1BH) to prepare an active silicic acid aqueous solution. The SiO ₂ concentration in the obtained active silicic acid aqueous solution was 4.0% by mass, and the pH was 2.9. Further, Na ₂ O in terms of concentration was 0.1% by mass or less.
(B) Preparation of seed solution 500 g of distilled water was heated to 100 ° C. in a 5 liter glass reaction vessel equipped with a refluxer, a stirrer, and a thermometer. While maintaining this hot water at 100 ° C., a total of 450 g of the above active silicic acid aqueous solution was added at a rate of 1.5 g / min to prepare a seed solution.
(C) Preparation of Silica Fine Particle Dispersion In the glass reaction vessel described above, 0.015 mol of ammonia was added to 950 g of the seed solution and stabilized, and the mixture was heated to 100 ° C. A total of 550 g of the above active silicic acid aqueous solution was added to the seed solution at a rate of 1.5 g / min. After completion of the addition of activated silicic acid, the solution was kept at 100 ° C. and heated to reflux for 9 hours to obtain a silica fine particle dispersion. This dispersion was concentrated by an evaporator to prepare a 10% by mass silica fine particle dispersion.
The particle diameter of this silica was 0.1 μm.

"Treatment with cationic compounds"
10 parts by mass of a cationic compound having a 5-membered ring amidine structure (product name: SC-700M, molecular weight: 30,000) having a 5-membered ring amidine structure is added to 100 parts by mass of this silica fine particle dispersion, and a high-speed flow collision type homogenizer is added. Was further dispersed to prepare a 10% by mass cationic polymer-silica composite particle dispersion having an average secondary particle size of 0.1 μm. The pore volume of this composite particle by BET was 0.4 ml / g.

"Preparation of coating solution for ink receiving layer"
As a fine pigment, 100 parts by weight (solid content) of the above cationic polymer-silica composite particle dispersion, 18 parts by weight of polyvinyl alcohol having a polymerization degree of 3500 and a saponification degree of 88.5% as a binder, and a dispersant (Toa Gosei) An aqueous dispersion (concentration: 15% by mass) was prepared by mixing 0.05 part by mass, trade name: Aron SD-10) manufactured by the company.

"Formation of ink-receiving layer"
An ink jet recording material was prepared in the same manner as in Example 1 except that the ink receiving layer coating solution was used. The dry coating amount of the ink receiving layer was 22 g / m ² .
The Cobb water absorption (30 second value) of the surface of the paper support on which the ink receiving layer was applied was 19.4 g / m ² and the Oken smoothness was 908 seconds.

Comparative Example 4
[Paper support]
Add 10 parts of calcined kaolin to 100 parts of hardwood bleached kraft pulp (LBKP: freeness 440 ml CSF), add 1.0 part of cationic starch, 0.7 part of rosin sizing agent, and 2.0 parts of sulfuric acid band. To make a papermaking raw material, paper is made using a long mesh multi-cylinder paper machine, the moisture is dried to 10%, and a 7% aqueous solution of oxidized starch is applied at 4 g / m ² on both sides with a size press and dried. A paper support (no coating layer) having a basis weight of 190 g / m ² was obtained by drying to a moisture content of 5.0%.

[Manufacture of inkjet recording medium]
An ink receiving layer was formed in the same manner as in Example 1 using the obtained paper support.
The Cobb water absorption (30 second value) of the surface of the paper support on which the ink receiving layer was applied was 46.3 g / m ² , and the Oken type smoothness was 8 seconds.

Evaluation Method The ink absorbability, gloss, image quality, and cockling resistance of the obtained ink jet recording material were evaluated by the following methods. For the evaluation, a dye ink jet printer (manufactured by EPSON, trademark: PM-G820, print mode: EPSON photographic paper clean mode) was used. The evaluation results are shown in Table 1.

"Color density of recorded images"
The solid color portion was printed in black, and the color density was measured with a Macbeth reflection densitometer (model: Macbeth RD-920, manufactured by Macbeth Co.).

"Glossy"
An ISO-400 image (“high-definition color digital standard image data ISO / JIS-SCID”, p13, image name: fruit basket) is printed on the sample recording medium, and the image is printed on the surface of the recording medium. It visually observed from the angle which inclined, and evaluated in the following five steps.
5: Glossiness similar to that of silver halide photography.
4: Slightly inferior to silver salt photograph, but has a sufficient gloss.
3: The glossy paper is not glossy but has a semi-glossy gloss.
2: Gloss is higher than mat.
1: Glossiness close to mat.

"Cockling resistance"
A black solid was printed on the recording medium that was tested, and it was visually observed whether there was cockling (waves parallel to the paper feeding direction) in the solid printed image, and the following three stages were evaluated. Cockling is a phenomenon that occurs when a sheet tries to stretch due to moisture in the ink that has been driven in.
○: Almost no cockling is observed.
(Triangle | delta): Cockling is recognized and there exists a problem practically.
X: The cockling is tremendously difficult to withstand practical use.

Claims (3)

In an inkjet recording medium having an ink receiving layer on a support, the support contains a pigment and a binder on the surface of a paper base, and the coating layer contains 5 to 50 parts by mass of the binder with respect to 100 parts by mass of the pigment. At least one layer (however, the latex polymer having a glass transition temperature of −10 to 50 ° C. does not have a water-resistant layer coated with 3 to 12 g / m ² ) , and JIS of the coated layer surface A paper support having a Cobb water absorption value of 30 seconds of 20.0 g / m ² or less as defined in P8140, an ink-receiving layer formed on the coating layer of the support, and vapor phase method silica Characterized in that it is a coating layer obtained mainly by treating with a cationic compound and having a fine volume of BET pore volume of 0.5 ml / g or more and an average particle size of 700 nm or less and an adhesive as main components. Inkjet recording material. 2. The ink jet recording material according to claim 1, wherein the pigment contained in the coating layer of the paper support contains as a main component one selected from kaolin, calcium carbonate, and satin white. The ink jet recording material according to claim 1 or 2, wherein the pigment contained in the coating layer of the paper support has a particle diameter of 0.2 µm or more and 10 µm or less .