JP2021154719A - Method for manufacturing inkjet recording material - Google Patents

Abstract

To provide a method for manufacturing an inkjet recording material which enables manufacture of an inkjet recording material that has good color development property when being printed with pigment ink and is excellent in water resistance and ink fixability.SOLUTION: A method for manufacturing an inkjet recording material includes coating a coating liquid for an ink receptive layer containing at least silica dispersed on an alkali condition, an anionic or nonionic water-insoluble resin and polyvinyl alcohol onto a support, and drying the coating liquid, forming a coated film, coating a coating liquid containing calcium salt onto the coated film, then drying the coating liquid, and forming an ink receptive layer.SELECTED DRAWING: None

Description

The present invention relates to a method for producing an inkjet recording material, which provides an inkjet recording material having good color development when printed with a pigment ink and excellent water resistance and ink fixability.

The inkjet recording method is widely used as an output method for offices and homes because it is easy to colorize and miniaturize the device and the operating sound of the device is quiet. Further, in the recording method, the printing speed has been increased with the progress of the printer, and the media is also required to have high ink absorbency and high ink fixability. Recently, the outdoor durability of printing inks marketed by each printer manufacturer has improved dramatically, so the inkjet recording method is used not only for indoor applications but also for outdoor advertisements such as large signboards and illuminated signboards. The number of cases that are being printed is increasing.

Printing inks used in the inkjet recording method are roughly classified into water-based dye inks in which colored dyes are dissolved in water, water-based pigment inks in which colored pigments are dispersed in water, and solvent inks in which colored pigments are dispersed in organic solvents. NS. As a printing ink used for producing a printed matter for outdoor use, a pigment ink is widely used from the viewpoint of obtaining an image having excellent water resistance, weather resistance, image sharpness and the like. In addition, printed matter used for outdoor applications is required to have high durability not only on the printing ink but also on the recording material side, and is used as a test method for image stability (weather resistance, water resistance) under outdoor conditions. Test standards such as ISO 18930: 2011 have also been established.

An inkjet recording material generally known for indoor use has an ink receiving layer containing a pigment such as silica and a water-soluble resin such as polyvinyl alcohol as a binder component on a support, and the recording material. Shows very good performance in terms of print quality such as color development and ink absorption. For example, in Japanese Patent Application Laid-Open No. 2005-1117 (Patent Document 1), when wet pulverized silica obtained by dispersing under conditions of pH 7 to 13 is contained in an ink receiving layer and printed with a pigment ink. It has been shown that an inkjet recording material having excellent color development and ink absorbency can be obtained. Further, in Japanese Patent Application Laid-Open No. 2002-274022 (Patent Document 2), when printing is performed with a pigment ink by an inkjet recording material obtained by blending a vapor phase method silica dispersion liquid containing an alkali metal hydroxide. It is described that good color development can be obtained.

On the other hand, it is known that when the ink receiving layer contains a calcium salt, bleeding during printing can be reduced and good color development can be obtained. For example, in the pamphlet of International Publication No. 2013/121860 (Patent Document 3), the coating liquid for the coating layer composed of calcium carbonate, polyvinyl alcohol, phosphate esterified starch, and cationic resin is described as calcium chloride, calcium nitrate, etc. It is described that by containing a calcium salt, bleeding at the time of printing is suppressed and good color development can be obtained.

However, an inkjet recording material having an ink receiving layer containing a water-soluble resin such as polyvinyl alcohol as a binder as described in Patent Documents 1 to 3 described above cannot satisfy the durability required for outdoor use. It could not be done, and deterioration such as cracking and peeling of the ink receiving layer occurred, and a big problem remained especially with respect to water resistance.

A method of using a water-insoluble resin as the main component of a binder as a method for improving the water resistance of an inkjet recording material having an ink receiving layer composed of a pigment such as silica and a water-soluble resin such as polyvinyl alcohol on a support. It has been known. For example, Japanese Patent Application Laid-Open No. 11-1238667 (Patent Document 4) shows that a recording medium containing silica and a cationic acrylic resin in an ink receiving layer suppresses bleeding and provides weather resistance. Further, in Japanese Patent Application Laid-Open No. 2018-43410 (Patent Document 5), inorganic particles are used in the ink receiving layer, and as a binder, a cationic or nonionic acrylic resin, a polycarbonate-modified urethane resin, a polyether-modified urethane resin, or the like is used. It has been shown that the recording medium contained improves scratch resistance, water resistance, and scratch resistance in a wet state. Further, Japanese Patent Application Laid-Open No. 2002-52812 (Patent Document 6) has excellent water resistance and weather resistance due to a recording medium containing silica as an inorganic pigment in the ink receiving layer and a cationic acrylic resin as a binder. It has been shown that an inkjet recording material can be obtained.

However, it cannot be said that the inkjet recording material containing the cationic acrylic resin described in Patent Document 4 sufficiently satisfies the color development property, the weather resistance, and the ink fixability. Further, in the inkjet recording material containing the cationic resin described in Patent Documents 5 and 6, the ink receiving layer has a multivalent value such as a water-soluble aluminum salt or a calcium compound in order to improve color development and ink fixability. Although it contains a metal compound, further improvement in color development has been desired.

On the other hand, Japanese Patent Application Laid-Open No. 2002-331745 (Patent Document 7) shows a method for producing an inkjet recording material, which is less likely to cause cracks during production and can obtain an inkjet recording material with improved coating uniformity. There is. In such a production method, it is described that a porous layer containing a hydrophilic binder and fine particles is applied on a support, and an additive-containing coating liquid is applied after the reduced rate drying region of the applied porous layer. As an example of the additive, polyvalent metal compounds such ^{as Mg 2+} , Ca ²⁺ , Zr ²⁺ , and Al ^{3+ are exemplified.}

Japanese Unexamined Patent Publication No. 2005-1117 JP-A-2002-274022 International Publication No. 2013/121860 Pamphlet Japanese Unexamined Patent Publication No. 11-1238667 JP-A-2018-43410 JP-A-2002-52812 JP-A-2002-331745

An object of the present invention is to provide an inkjet recording material having good color development when printed with a pigment ink and excellent in water resistance and ink fixability.

The above object of the present invention is achieved by the following invention.
(1) A coating liquid for an ink receiving layer containing at least silica, anionic or nonionic water-insoluble resin, and polyvinyl alcohol dispersed under alkaline conditions is applied onto the support and dried to form a coating film. A method for producing an inkjet recording material, which is obtained by further applying a coating liquid containing a calcium salt to the coating film and then drying the coating film to form an ink receiving layer.
(2) The water-insoluble resin described above is an anionic acrylic resin, and after forming an ink receiving layer, colloidal silica having an average particle diameter of at least 60 nm or less, or a minimum film forming temperature of 40 is further formed on the ink receiving layer. The method for producing an inkjet recording material according to (1) above, wherein a coating liquid for a surface layer containing an organic emulsion at ° C. or higher is applied and dried.
(3) The above (1) or the above (1) or (1) above, in which the silica dispersed under the above alkaline conditions is the vapor phase silica, the water-insoluble resin is the anionic acrylic resin, and the polyvinyl alcohol is the completely saponified polyvinyl alcohol. The method for producing an inkjet recording material according to 2).

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an inkjet recording material having good color development when printed with a pigment ink and having excellent water resistance and ink fixability.

The present invention will be described in detail below.

As the support contained in the inkjet recording material in the present invention, a non-water-absorbent support is preferable from the viewpoint of obtaining an inkjet recording material having excellent water resistance. Examples of the non-water-absorbent support include resin films such as polyethylene, polypropylene, polyvinyl chloride, diacetate resin, triacetate resin, cellophane, acrylic resin, polyethylene terephthalate, and polyethylene naphthalate, and paper and film mainly made of resin. Examples thereof include synthetic paper having the above-mentioned characteristics, and resin-coated paper in which one or both sides of a base paper are coated with a polyolefin resin. Of these, synthetic paper is preferable from the viewpoint of excellent water resistance and a texture close to that of a recorded matter printed on paper.

Synthetic paper is roughly classified into film-forming synthetic paper, fiber-based synthetic paper, and film-laminated synthetic paper, depending on the manufacturing method. Film forming method Synthetic paper is produced by a film forming method in which a synthetic resin as a raw material is molded into a film. As a film-forming synthetic paper, for example, it is commercially available from Yupo Corporation as Yupo (registered trademark). Fiber method Synthetic paper is manufactured by using resin fibers made from synthetic resin instead of pulp. As the fiber method synthetic paper, for example, it is commercially available from Teijin Frontier Co., Ltd. as Laser Ecopet (registered trademark). Film Laminating Method Synthetic paper is produced by laminating a film on the surface of conventional paper. As a film-laminated synthetic paper, for example, it is commercially available from Nippon Paper Papylia Co., Ltd. as OPER (registered trademark). In the present invention, a film synthetic paper is preferably used from the viewpoint of the water resistance of the obtained inkjet recording material and the texture of the recorded material.

The surface of the support on which the ink receiving layer is applied may have an undercoat layer. This undercoat layer is previously applied and dried on the surface of the support before the ink receiving layer is applied, and mainly contains a water-soluble polymer compound or polymer latex capable of forming a film. Is preferable. Here, the term "mainly" means that the ratio of the water-soluble polymer compound or the polymer latex to the total solid content of the undercoat layer is 50% by mass or more. The content of water-soluble polymer compound or a polymer latex in the undercoat layer is preferably ^{10~500mg / m 2, 20~300mg / m} 2 is more preferable. Further, the undercoat layer may also contain a surfactant or a dural agent.

Next, each component contained in the coating liquid for the ink receiving layer of the present invention will be described.

In the present invention, the coating liquid for the ink receiving layer contains silica dispersed under alkaline conditions. More specifically, it contains silica dispersed in a state where an alkaline compound is added so that the pH of the silica dispersion liquid exceeds 7. By dispersing under alkaline conditions, high-concentration dispersion becomes possible, and as a result, the dispersion efficiency is increased, and finer pulverization is possible, and as a result, good color development can be obtained. Further, by using the high-concentration dispersion liquid, it is possible to increase the concentration of silica in the coating liquid at the time of preparing the coating liquid, and it is possible to obtain advantages such as improvement in production efficiency. The pH of the dispersed silica dispersion is preferably 8.0 or higher, more preferably 9.0 or higher. The upper limit is preferably 13.0 or less.

In the present invention, the silica contained in the coating liquid for the ink receiving layer can be roughly classified into wet method silica and vapor phase method silica depending on the production method. Wet silica is classified into sedimentation silica, gel silica, and sol silica depending on the production method. Precipitation method Silica is produced by reacting sodium silicate and sulfuric acid under alkaline conditions, and the silica particles that have grown particles are aggregated and settled, and then commercialized through the steps of filtration, washing with water, drying, crushing and classification. As the sedimentation method silica, for example, it is commercially available from Tosoh Silica Co., Ltd. as Nip Seal (registered trademark). Gel method silica is produced by reacting sodium silicate and sulfuric acid under acidic conditions. During aging, the fine particles dissolve and reprecipitate so as to bond the other primary particles to each other, so that the clear primary particles disappear and form relatively hard aggregated particles with an internal void structure. As the gel method silica, for example, Mizusawa Industrial Chemicals Co., Ltd. sells it as Mizukasil (registered trademark), and Tosoh Silica Co., Ltd. sells it as Nipgel (registered trademark). Sol method silica is also called colloidal silica, and is obtained by heat-aging silica sol obtained through compound decomposition with acid of sodium silicate or through an ion exchange resin layer. For example, Nissan Chemical Industries, Ltd. as Snowtex (registered trademark). It is commercially available. In addition, vapor phase silica is also called dry silica, and is generally produced by a flame hydrolysis method. Specifically, it is produced by burning silicon tetrachloride together with hydrogen and oxygen. As the vapor phase silica, for example, it is commercially available from Nippon Aerosil Co., Ltd. as Aerosil (registered trademark). The content of the silica in the ink-receiving layer is preferably ^{1~40g / m 2, 3~30g / m} 2 is more preferable.

Various inorganic and organic compounds can be used as the alkaline compound to be added to the dispersion medium when silica is dispersed under alkaline conditions. For example, potassium hydroxide, sodium hydroxide, ammonium hydroxide, sodium acetate, sodium carbonate, etc. Ammonium carbonate, monoethanolamine, isopropylamine, ethylenediamine, propanediamine, diethanolamine, dipropylamine, dibutylamine, triethanolamine, piperazin, 2-methylpiperazin, N-methylpiperazine, 2-piperidinethanol, and aminoethylethanolamine. At least one of the above is used, and among them, sodium hydroxide is preferably used.

In the present invention, the coating liquid for the ink receiving layer contains a water-insoluble resin. Water-insoluble resins are classified into anionic, cationic, and nonionic depending on the type of hydrophilic groups contained therein. In the present invention, anionic or nonionic water-insoluble resins are used. Examples of the anionic group contained in the water-insoluble resin include a carboxy group, a sulfo group, a sulfate ester group, and a phosphoric acid ester group. On the other hand, examples of the nonionic group contained in the water-insoluble resin include a hydroxy group, an ether group, and an amide group. Examples of the water-insoluble resin that can be used in the present invention include polyester resin, polyvinyl chloride resin, polystyrene resin, polycarbonate resin, polyurethane resin, vinyl chloride-vinyl acetate copolymer resin, and acrylic. Examples thereof include based resins and polyvinyl butyral resins. When the ink receiving layer contains the above-mentioned water-insoluble resin, good water resistance and weather resistance can be obtained. The water-insoluble resin may be used alone or in combination of two or more. The content of the anionic or nonionic water-insoluble resin is preferably 20 to 200% by mass, preferably 40 to 150% by mass, based on the solid content of the silica described above, as the total amount of the binder combined with polyvinyl alcohol described later. More preferred.

When the water-insoluble resin is an anionic acrylic resin, a surface layer containing colloidal silica having an average particle diameter of 60 nm or less, which will be described later, or an organic emulsion having a minimum film forming temperature of 40 ° C. or more is formed on the ink receiving layer. When provided, it is preferable because an inkjet recording material having particularly excellent color development property can be obtained.

As the polyvinyl alcohol contained in the coating liquid for the ink receiving layer, various modified polyvinyl alcohols such as anion-modified polyvinyl alcohol, silanol-modified polyvinyl alcohol, and acetoacetyl-modified polyvinyl alcohol can be used in addition to general polyvinyl alcohol. be. One type of polyvinyl alcohol may be used alone, or two or more types may be used in combination. The content of polyvinyl alcohol in the ink receiving layer is preferably 1 to 65% by mass, more preferably 5 to 30% by mass, based on the total binder combined with the water-insoluble resin described above.

The silica dispersed under alkaline conditions contained in the coating liquid for the ink receiving layer of the present invention is vapor phase silica, the water-insoluble resin is an anionic acrylic resin, and polyvinyl alcohol is completely saponified polyvinyl alcohol. In this case, an inkjet recording material having particularly excellent glossiness can be obtained. Further, the glossiness can be further improved by combining with a surface layer containing colloidal silica having an average particle size of 60 nm or less or an organic emulsion having a minimum film forming temperature of 40 ° C. or more, which will be described later.

In the present invention, the coating liquid for the ink receiving layer may contain a thickener in order to improve the coating property when applied on the support. Thickeners are generally classified into polymer type and association type. The polymer-type thickener exhibits a thickening effect when a polymer having a large molecular weight dissolves in water under alkaline conditions and is entangled with each other. Acrylic acid-based thickeners are a typical example of polymer-type thickeners. The associative thickener has hydrophobic groups at both ends of the hydrophilic polymer, and the hydrophobic substance and the hydrophobic group are bonded by the associative force to construct a network structure and exert a thickening effect. A typical example of an association type thickener is a polyether thickener. In the present invention, a polymer-type thickener is preferably used because the silica dispersion liquid dispersed under alkaline conditions maintains good dispersibility. The content of the thickener in the ink-receiving layer is preferably ^{50~500mg / m 2, 100~300mg / m} 2 is more preferable.

The ink receiving layer of the inkjet recording material obtained by the present invention contains a calcium salt. The calcium salt acts as an ink fixer. Examples of the calcium salt include calcium chloride, calcium nitrate, calcium sulfate, calcium acetate and the like. Among them, calcium chloride and calcium nitrate are preferably used from the viewpoint of scratch resistance of the pigment ink. The content of the calcium salt in the ink-receiving layer is preferably ^{0.1~10.0g / m 2, 0.2~5.0g / m} 2 is more preferable.

When the coating liquid for the ink receiving layer is applied and dried to form a coating film, and then the coating liquid containing a calcium salt is applied, it is considered that the degree of cationization of the surface of the porous body of the obtained ink receiving layer is high. Be done. Since the ink for inkjet recording is generally anionic, the inkjet recording material having a high degree of cationization on the surface of the ink receiving layer obtained by the present invention enables particularly strong ink fixing.

When the calcium salt is directly added to the above-mentioned coating liquid for the ink receiving layer, the water-insoluble resin aggregates and the coating liquid for the ink receiving layer cannot be obtained, as shown in Examples described later. Further, after the coating liquid for the ink receiving layer is applied and dried to form a coating film, a coating liquid containing an ink fixing agent other than the calcium salt such as a cationic resin or polyaluminum chloride is applied and dried to receive the ink. When the layer is formed, good color development and ink fixability cannot be obtained as shown in Examples described later. Therefore, when a coating liquid containing an ink fixing agent other than the calcium salt and the calcium salt is applied to the coating film obtained by applying and drying the coating liquid for the ink receiving layer, the ink fixing agent other than the calcium salt is a calcium salt. It is preferable to use in combination within a range not exceeding the content of.

In the present invention, the ink receiving layer can further contain an ultraviolet absorber and a light stabilizer in addition to the above-mentioned components. Since the ultraviolet absorber and the light stabilizer are present in the ink receiving layer, the coloring material can be protected from fading due to gas, light, etc., and the weather resistance of the coloring material can be improved. Examples of the ultraviolet absorber include benzotriazole-based, hydroxyphenyltriazine-based, benzphenone-based, and phenylsalicylate-based compounds. Moreover, as a light stabilizer, a hindered amine system is exemplified. One type of these may be used, or two or more types may be used in combination. The ultraviolet absorber and the light stabilizer are preferably contained in the coating liquid for the ink receiving layer.

In the present invention, the ink receiving layer is further known to include various known color dyes, color pigments, antioxidants, pigment dispersants, defoamers, leveling agents, preservatives, fluorescent whitening agents, cross-linking agents, pH adjusters and the like. Additives can also be included.

In the present invention, the solid content coating amount of the ink receiving layer coating solution is preferably from 5 to 60 g / ^{m 2,} and more preferably 10 to 50 g / ^{m 2.}

In the present invention, the coating method of the coating liquid for the ink receiving layer is not particularly limited, and a known coating method can be used. For example, there are a slide bead method, a curtain method, an extrusion method, an air knife method, a roll coating method, a rod bar coating method and the like.

In the present invention, the coating method of the coating liquid containing the calcium salt is not particularly limited, and a known coating method can be used. For example, there are a slide bead method, a curtain method, an extrusion method, an air knife method, a roll coating method, a rod bar coating method, a slot die method, a spray method, a gravure method, a microgravure method and the like.

In the present invention, the water-insoluble resin contained in the coating liquid for the ink receiving layer is an anionic acrylic resin, and after forming the ink receiving layer, colloidal silica having an average particle diameter of at least 60 nm or less is further placed on the ink receiving layer. Alternatively, it is preferable to apply a surface layer coating liquid containing an organic emulsion having a minimum film forming temperature of 40 ° C. or higher and dry it. The inkjet recording material thus obtained has particularly good color development properties. If the average particle size of the colloidal silica contained in the surface layer coating liquid is larger than 60 nm, the adhesion of the colloidal silica to the ink receiving layer becomes poor, and the surface layer may easily fall off. The average particle size of colloidal silica can be obtained from the measured specific surface area and density by the BET method.

In the present invention, the particle shape of colloidal silica having an average particle diameter of 60 nm or less may be spherical, chain-shaped, or necklace-shaped. Examples of spherical colloidal silica include Snowtex (registered trademark) ST-S (average particle size 9 nm), Snowtex ST-30 (average particle size 12 nm), and Snowtex ST-, which are commercially available from Nissan Chemical Co., Ltd. Examples thereof include 50T (average particle size 22 nm), Snowtex ST-30L (average particle size 45 nm), Snowtex ST-YL (average particle size 60 nm), and examples of chain-shaped or necklace-shaped colloidal silica. , Snowtex ST-PS-S (average particle size 15 nm), Snowtex ST-PS-M (average particle size 25 nm) and the like can be exemplified.

Generally, in an organic emulsion, particles of a synthetic resin are uniformly dispersed in water, and it is preferable to use such an organic emulsion in the present invention as well. Further, the minimum film forming temperature of the organic emulsion contained in the coating liquid for the surface layer is preferably 40 ° C. or higher. When the minimum film forming temperature of the organic emulsion is less than 40 ° C., a coating liquid for a surface layer containing the organic emulsion is applied to the surface of the ink receiving layer, and then a film is formed on the surface of the ink receiving layer when it is dried. In some cases, ink absorption is hindered and a clear image cannot be obtained. The minimum film-forming temperature can be measured using a minimum film-forming temperature measuring device conforming to the temperature gradient plate method specified in ISO standard 2115.

Examples of the components of the synthetic resin particles constituting the above-mentioned organic emulsion include acrylic resin, styrene resin, urethane resin, acrylamide resin, epoxy resin and the like, and an organic emulsion in which these resins are mixed. There may be. Furthermore, these resin components may be a complex with colloidal silica. Of these, an acrylic resin or a styrene-acrylic resin is preferable from the viewpoint of obtaining good color development. As such an organic emulsion, for example, Movinyl (registered trademark) 1711, 6520, 8055A, etc. are commercially available from Japan Coating Resin Co., Ltd., and these can be obtained and used.

In the coating liquid for the surface layer in the present invention, it is preferable that colloidal silica having an average particle size of 60 nm or less and an organic emulsion having a minimum film forming temperature of 40 ° C. or more are contained in a solvent component mainly composed of water. Two or more types of colloidal silica having an average particle size of 60 nm or less, or two or more types of organic emulsion having a minimum film forming temperature of 40 ° C. or more may be used in combination as the coating liquid for the surface layer, and the average particle size is 60 nm or less. Colloidal silica and an organic emulsion having a minimum film forming temperature of 40 ° C. or higher may be used in combination. Further, in addition to the above-mentioned components, it may contain a UV absorber, a light stabilizer, and known additives such as a surfactant, a defoaming agent, a leveling agent, a preservative, a fluorescent whitening agent, and a pH adjuster. Although it is possible, from the viewpoint of obtaining good color development, colloidal silica having an average particle size of 60 nm or less in the total solid content contained in the coating liquid for the surface layer, or the minimum film forming temperature in the total solid content is 40. The proportion of the organic emulsion at ° C. or higher is preferably 90% by mass or more, more preferably 95% by mass or more.

In the present invention, the coating method of the coating liquid for the surface layer is not particularly limited, and a known coating method can be used. For example, the same method as the coating method of the coating liquid containing a calcium salt can be exemplified.

Hereinafter, the present invention will be described in detail with reference to examples. Needless to say, the present invention is not limited to the examples. Hereinafter, "%" is a mass% unless otherwise specified, and "part" is a mass part unless otherwise specified.

(Example 1)
<Preparation of silica dispersion 1>
2.5 parts of sodium hydroxide and 100 parts of gel method silica (Mizukasil P-78A manufactured by Mizusawa Industrial Chemicals Co., Ltd.) are added to water, and dispersion treatment is performed with a high-speed disperser. Silica with a solid content concentration of 16%. The dispersion liquid 1 was prepared. The pH of the silica dispersion 1 was 10.2.

<Preparation of coating liquid 1 for ink receiving layer>
Silica dispersion 1 (as solid content) 102.5 parts Polyvinyl alcohol 10 parts (Kuraray Poval (registered trademark) 25-98R, manufactured by Kuraray Co., Ltd.)
Anionic acrylic resin (water-insoluble resin) (as solid content) 50 parts (AE986B manufactured by E-Tech Co., Ltd.)
Surfactant 0.5 parts (Orfin (registered trademark) E1010 manufactured by Nissin Chemical Industry Co., Ltd.)
2.0 parts of polymer thickener (SN thickener 640 manufactured by San Nopco Ltd.)
Using water as a solvent, the solid content concentration of the coating liquid was adjusted to 16%.

<Preparation of overcoat liquid 1>
Calcium chloride was dissolved in water so as to have a CaCl ₂ equivalent of 3% to prepare an overcoat liquid 1.

<Manufacturing of inkjet recording material>
As the support, a synthetic paper having a thickness of 110 μm (New Yupo FGS110 manufactured by Yupo Corporation) obtained by a biaxially stretched film forming method was used, and the coating liquid 1 for the ink receiving layer was applied on the support in terms of dry solid content. It was applied by a rod bar coating method so as to be 16 g / m ^2. Then, it was dried with warm air at 40 ° C. for 5 minutes using a film dryer to form a coating film. Next, the overcoat liquid 1 is applied onto the coating film obtained above by a ^{rod bar coating method so that the dry solid content is 17 g / m 2} together with the coating film, and warm air at 40 ° C. is again applied. The ink-jet recording material of Example 1 was obtained by drying for 5 minutes to form an ink receiving layer.

(Example 2)
<Preparation of overcoat liquid 2>
Calcium nitrate was dissolved in water so as to be 3% in terms of Ca (NO ₃ ) _{2, and an overcoat liquid 2 was prepared.}

In the preparation of the inkjet recording material of Example 1, the inkjet recording material of Example 2 was obtained in the same manner except that the overcoat liquid 1 was changed to the overcoat liquid 2 described above.

(Example 3)
<Preparation of overcoat liquid 3>
Calcium chloride _{was dissolved in water to 3% in terms of CaCl 2} and polyaluminum chloride to 2% to prepare an overcoat liquid 3.

In the preparation of the inkjet recording material of Example 1, the inkjet recording material of Example 3 was obtained in the same manner except that the overcoat liquid 1 was changed to the overcoat liquid 3 described above.

(Example 4)
<Preparation of silica dispersion 2>
1.8 parts of sodium hydroxide and 100 parts of gel method silica (Mizukasil P-78A manufactured by Mizusawa Industrial Chemicals Co., Ltd.) are added to water, and dispersion treatment is performed with a high-speed disperser. Silica with a solid content concentration of 21%. The dispersion liquid 2 was prepared. The pH of the silica dispersion 2 was 9.0.

In the production of the inkjet recording material of Example 1, the silica dispersion liquid 1 of the coating liquid 1 for the ink receiving layer is changed to the silica dispersion liquid 2 described above to prepare the coating liquid 2 for the ink receiving layer, and the coating liquid is applied. The inkjet recording material of Example 4 was obtained in the same manner except for the above.

(Example 5)
In the production of the inkjet recording material of Example 1, the anionic acrylic resin which is the water-insoluble resin in the production of the coating liquid 1 for the ink receiving layer is replaced with the anionic urethane resin (Hydran manufactured by DIC Corporation) which is the water-insoluble resin. A coating liquid 3 for an ink receiving layer was prepared by changing to (registered trademark) WLS-210), and the inkjet recording material of Example 5 was obtained in the same manner except that the coating liquid was applied.

(Example 6)
In the production of the inkjet recording material of Example 1, the anionic acrylic resin, which is a water-insoluble resin in the production of the coating liquid 1 for the ink receiving layer, is replaced with a nonionic acrylic resin (Japan Coating Resin Co., Ltd.), which is a water-insoluble resin. A coating liquid 4 for an ink receiving layer was prepared by changing to MOVIN 7720), and the inkjet recording material of Example 6 was obtained in the same manner except that the coating liquid was applied.

(Comparative Example 1)
In the preparation of the inkjet recording material of Example 1, the inkjet recording material of Comparative Example 1 was obtained in the same manner except that the overcoat liquid was not applied.

(Comparative Example 2)
<Preparation of silica dispersion 3>
In the preparation of the silica dispersion liquid 1 described above, the silica dispersion liquid 3 was prepared in the same manner except that sodium hydroxide was not added. The pH of the silica dispersion 3 was 6.1.

In the production of the inkjet recording material of Example 1, the silica dispersion liquid 1 of the coating liquid 1 for the ink receiving layer is changed to the silica dispersion liquid 3 described above to prepare the coating liquid 5 for the ink receiving layer, and the coating liquid is applied. In the same manner except for the above, the inkjet recording material of Comparative Example 2 was obtained.

(Comparative Example 3)
In the production of the inkjet recording material of Example 1, the anionic acrylic resin in the production of the coating liquid 1 for the ink receiving layer was changed to 60 parts, and the coating liquid 6 for the ink receiving layer was prepared and coated without using polyvinyl alcohol. In the same manner except for the above, the inkjet recording material of Comparative Example 3 was obtained.

(Comparative Example 4)
In the preparation of the inkjet recording material of Example 1, the polyvinyl alcohol in the preparation of the coating liquid 1 for the ink receiving layer was changed to 60 parts, and the coating liquid 7 for the ink receiving layer was prepared and coated without using the anionic acrylic resin. In the same manner except for the above, the inkjet recording material of Comparative Example 4 was obtained.

(Comparative Example 5)
<Preparation of overcoat liquid 4>
Polydialyldimethylammonium chloride (Charol (registered trademark) DC-902P manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), which is a cationic resin, was dissolved in water to a concentration of 3% to obtain an overcoat liquid 4.

In the preparation of the inkjet recording material of Example 1, the inkjet recording material of Comparative Example 5 was obtained in the same manner except that the overcoat liquid 1 was changed to the overcoat liquid 4 described above.

(Comparative Example 6)
<Preparation of overcoat liquid 5>
Polyaluminum chloride, which is a polyvalent metal salt, was dissolved in water to a concentration of 3% to obtain an overcoat liquid 5.

In the preparation of the inkjet recording material of Example 1, the inkjet recording material of Comparative Example 6 was obtained in the same manner except that the overcoat liquid 1 was changed to the overcoat liquid 5 described above.

(Comparative Example 7)
In the preparation of the coating liquid 1 for the ink receiving layer described above, the preparation of the coating liquid 8 for the ink receiving layer was attempted in the same manner except that 10 parts of _{calcium chloride was added to the coating liquid for the ink receiving layer in terms of CaCl 2.} However, due to the aggregation of the anionic acrylic resin, the coating liquid 8 for the ink receiving layer could not be prepared.

(Comparative Example 8)
In the preparation of the coating liquid 1 for the ink receiving layer described above, the anionic acrylic resin which is a water-insoluble resin is changed to a cationic acrylic resin which is a water-insoluble resin (Mobile (registered trademark) 7820 manufactured by Japan Coating Resin Co., Ltd.). An attempt was made to prepare the above-mentioned coating liquid 9 for the ink receiving layer in the same manner except for the modification, but the coating liquid 9 for the ink receiving layer could not be prepared due to the aggregation of the cationic acrylic resin.

On the ink receiving layer surface of the inkjet recording materials of Examples 1 to 6 and Comparative Examples 1 to 6 obtained as described above, a commercially available pigment inkjet printer (SC-PX5VII manufactured by Seiko Epson Corporation, print quality: high definition) , Color correction: None), after printing the following evaluation image, it was further dried, and the following evaluation was performed.

For the evaluation image, cyan, magenta, yellow, black, and red, green, blue, and white (unprinted areas) solid images are 25 mm long and 20 mm wide, with 0 in 2 rows and 4 rows. They were arranged at intervals of .5 mm so that there was a blank area between each solid image.

<Color development>
All solid image parts were measured with a spectrophotometer i1Pro manufactured by X-Rite, and ^{Gamut values in L *} a ^* b ^* Volume were calculated to evaluate color development. In this evaluation method, the larger the Gamut value, the higher the color development. The evaluation results are shown in Table 1.
◯: Gamut value is 270000 or more.
Δ: Gamut value is 240000 or more and less than 270000.
X: Gamut value is less than 240000.

<Water resistance>
The inkjet recording material on which the above-mentioned image for evaluation was printed was immersed in warm water at 50 ° C. for 168 hours, and then the printed portion was lightly rubbed with a finger in warm water for evaluation. The evaluation results are shown in Table 1.
◯: No significant change is observed in the ink receiving layer.
Δ: The ink and the receiving layer were partially peeled off.
X: The ink receiving layer was easily peeled off from the surface of the base material.

<Ink fixability>
When printing an image for evaluation as described above, the ink density setting of the inkjet printer is set to 1.5 times, the ink ejection amount is increased compared to the normal printing mode, and the boundary portion of the solid image is blurred. Was evaluated. In this evaluation method, it was assumed that the ink fixability was so high that there was no bleeding at the boundary. The evaluation results are shown in Table 1.
◯: There is no bleeding at the color boundary.
Δ: The color boundary is not clear, and the color is moving beyond the adjacent boundary.
X: The color boundary is not known, and the bleeding to the adjacent color is large.

From the results in Table 1, the inkjet recording material manufacturing method described in (1) above of the present invention has good color development when printed with pigment ink, and is also excellent in water resistance and ink fixability. It can be seen that recording material can be obtained.

(Example 7)
<Preparation of coating liquid 1 for surface layer>
Colloidal silica 1 (Snowtex ST-50T manufactured by Nissan Chemical Industries, Ltd., average particle size 22 nm) was diluted with water so that the solid content concentration became 30% to prepare a coating liquid 1 for the surface layer.

<Manufacturing of inkjet recording material>
On the ink receiving layer of the inkjet recording material of Example 1, the above-mentioned coating liquid 1 for the surface layer was applied together with the ink receiving layer by a rod bar coating method so ^{that the dry solid content was 19 g / m 2.} The ink jet recording material of Example 7 was obtained by drying with warm air at 40 ° C. for 5 minutes.

(Example 8)
In the production of the inkjet recording material of Example 7, the inkjet recording material of Example 8 was obtained in the same manner except that the inkjet recording material of Example 2 was used instead of the inkjet recording material of Example 1.

(Example 9)
In the production of the inkjet recording material of Example 7, the inkjet recording material of Example 9 was obtained in the same manner except that the inkjet recording material of Example 3 was used instead of the inkjet recording material of Example 1.

(Example 10)
In the production of the inkjet recording material of Example 7, the inkjet recording material of Example 10 was obtained in the same manner except that the inkjet recording material of Example 4 was used instead of the inkjet recording material of Example 1.

(Example 11)
In the preparation of the coating liquid 1 for the surface layer in the preparation of the inkjet recording material of Example 7, the colloidal silica 1 was changed to colloidal silica 2 (Snowtex ST-YL manufactured by Nissan Chemical Industries, Ltd., average particle diameter 60 nm). An inkjet recording material of Example 11 was obtained in the same manner except that the coating liquid 2 for the surface layer was prepared and the coating liquid was applied.

(Example 12)
In the preparation of the coating liquid 1 for the surface layer in the preparation of the inkjet recording material of Example 7, the colloidal silica 1 was changed to an organic emulsion 1 (Mobile 8055A manufactured by Japan Coating Resin Co., Ltd., minimum film forming temperature of 100 ° C. or higher). , The coating liquid 3 for the surface layer was prepared, and the inkjet recording material of Example 12 was obtained in the same manner except that the coating liquid was applied.

(Example 13)
In the preparation of the coating liquid 1 for the surface layer in the preparation of the inkjet recording material of Example 7, the colloidal silica 1 was changed to an organic emulsion 2 (Mobile 6520 manufactured by Japan Coating Resin Co., Ltd., minimum film forming temperature 50 ° C.). An inkjet recording material of Example 13 was obtained in the same manner except that the coating liquid 4 for the surface layer was prepared and the coating liquid was applied.

On the ink receiving layer surface of the inkjet recording materials of Examples 7 to 13 obtained as described above, a commercially available pigment inkjet printer (SC-PX5VII manufactured by Seiko Epson Corporation, print quality: high definition, color correction: none). Then, after printing the following evaluation image, it was further dried and the following evaluation was carried out. The evaluation results are shown in Table 2. Table 2 also shows the evaluation results of the inkjet recording material of Example 1 above.

For the evaluation image, cyan, magenta, yellow, black, and red, green, blue, and white (unprinted areas) solid images are 25 mm long and 20 mm wide, with 0 in 2 rows and 4 rows. They were arranged at intervals of .5 mm so that there was a blank area between each solid image.

<Color development>
All solid image parts were measured with a spectrophotometer i1Pro manufactured by X-Rite, and ^{Gamut values in L *} a ^* b ^* Volume were calculated to evaluate color development. In this evaluation method, the larger the Gamut value, the higher the color development.
⊚: Gamut value is 350,000 or more.
◯: Gamut value is 270000 or more and less than 350,000.
Δ: Gamut value is 240000 or more and less than 270000.
X: Gamut value is less than 240000.

<Water resistance>
The water resistance of the inkjet recording materials of Examples 7 to 13 obtained as described above was evaluated by the same method used for the inkjet recording materials of Examples 1 to 6 above.

<Ink fixability>
With respect to the inkjet recording materials of Examples 7 to 13 obtained as described above, the ink fixability was evaluated by the same method used for the inkjet recording materials of Examples 1 to 6 above.

From the results in Table 2, it can be seen that the method for producing an inkjet recording material described in (2) above of the present invention can obtain an inkjet recording material having particularly excellent color development when printed with a pigment ink.

(Example 14)
<Preparation of silica dispersion 4>
0.5 parts of sodium hydroxide and 100 parts of vapor phase silica (Aerosil A90G manufactured by Nippon Aerosil Co., Ltd.) are added to water, and dispersion treatment is performed with a high-speed disperser. Silica dispersion having a solid content concentration of 20% 4 was prepared. The pH of the silica dispersion 4 was 9.6.

<Preparation of coating liquid 10 for ink receiving layer>
Silica dispersion 4 (as solid content) 100.5 parts Polyvinyl alcohol 10 parts (Completely saponified polyvinyl alcohol JC-33 manufactured by Japan Vam & Poval Co., Ltd.)
Anionic acrylic resin (water-insoluble resin) (as solid content) 50 parts (AE986B manufactured by E-Tech Co., Ltd.)
Surfactant 0.5 parts (Orfin (registered trademark) E1010 manufactured by Nissin Chemical Industry Co., Ltd.)
Polymer type thickener 1.0 part (Somarex 270K manufactured by SOMAR Corporation)
Using water as a solvent, the solid content concentration of the coating liquid was adjusted to 20%.

<Manufacturing of inkjet recording material>
In the preparation of the inkjet recording material of Example 1, the inkjet recording material of Example 14 was obtained in the same manner except that the coating liquid 1 for the ink receiving layer was changed to the coating liquid 10 for the ink receiving layer described above.

(Example 15)
On the ink receiving layer of the inkjet recording material of Example 14, the above-mentioned coating liquid 2 for the surface layer was applied together with the ink receiving layer by a rod bar coating method so ^{that the dry solid content was 19 g / m 2.} The ink jet recording material of Example 15 was obtained by drying with warm air at 40 ° C. for 5 minutes.

<Color development, water resistance, and ink fixability>
With respect to the inkjet recording materials of Examples 14 and 15 and Examples 1 and 11 obtained as described above, the same method as that used for evaluating the inkjet recording materials of Examples 7 to 13 above was used. , Color development, water resistance, and ink fixability were evaluated. The results are shown in Table 3.

<Glossy>
The 75-degree mirror gloss of the surface layer of the inkjet recording materials of Examples 14 and 15 and Examples 1 and 11 obtained as described above was measured by a precision gloss meter (GM-26D manufactured by Murakami Color Technology Laboratory Co., Ltd.). Measured at. The results are shown in Table 3.

From the results in Table 3, it can be seen that an inkjet recording material having particularly excellent glossiness can be obtained by the method for producing an inkjet recording material described in (3) above of the present invention.

Claims (3)

A coating liquid for an ink receiving layer containing at least silica, anionic or nonionic water-insoluble resin, and polyvinyl alcohol dispersed under alkaline conditions is applied onto the support and dried to form a coating film, and further. A method for producing an inkjet recording material, which forms an ink receiving layer by applying a coating liquid containing a calcium salt to the coating film and then drying the coating liquid. The water-insoluble resin is an anionic acrylic resin, and after forming an ink receiving layer, colloidal silica having an average particle diameter of at least 60 nm or less or an organic having a minimum film forming temperature of 40 ° C. or more is further formed on the ink receiving layer. The method for producing an inkjet recording material according to claim 1, wherein a coating liquid for a surface layer containing an emulsion is applied and dried. The above-mentioned claim 1 or the above-mentioned claim 2 in which the silica dispersed under the alkaline conditions is a vapor phase silica, the water-insoluble resin is an anionic acrylic resin, and the polyvinyl alcohol is a completely saponified polyvinyl alcohol. The method for producing an inkjet recording material according to the above.