JP2014019054A - Inkjet recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording medium capable of obtaining an excellent image without whitening.SOLUTION: In an inkjet recording medium having an ink-receiving layer containing porous silica particles on a support, the porous silica particles are obtained by a method including steps for: adding a mixed liquid (A liquid) containing tetraalkoxysilane, alkylamine and alcohol into a mixed liquid (B liquid) containing ammonia, alcohol and water to generate hydrolysis and a condensation reaction of tetraalkoxysilane, and to thereby obtain silica particles; and removing alkylamine from the silica particles.

Description

  The present invention relates to an ink jet recording medium suitable for recording by discharging ink by an ink jet method.

  As a recording method using an ink jet method, a method using an ink jet recording medium in which a recording layer for receiving ink has a porous structure has been put into practical use. As an example, there is an ink jet recording medium that includes inorganic pigment particles and a water-soluble binder, and a recording layer having a high porosity is provided on a water-resistant support, and has a porous structure, so that the ink can be quickly dried. It has become possible to record photographic-like images such as excellent and high gloss.

  Ink jet recording methods are not only applied in the fields of office printers and home printers, but in recent years are also being applied in commercial printing fields. In this commercial printing field, an ink jet recording that does not have a photo-like surface that completely blocks the penetration of the ink solvent into the support, but has a printing texture, texture, and high-speed recording properties like general-purpose printing paper. Media is requested.

  In applications such as commercial printing, such as printing images at high speed or printing many images at once, or recording images on both sides, not only can images be recorded at higher speeds when recording images by ink ejection. In view of the quality as a recording material, it is required that the recorded image has a stable quality such as glossiness and fineness of the image. However, in situations where high quality or high performance is advancing, the influence of humidity environment or dry state after recording on image quality tends to be negligible when performing double-sided recording or multi-sheet processing or high-speed processing. is there.

  In connection with the above, for example, including gas phase method silica and a porous silica material having hexagonal structure pores having an average pore diameter of 0.8 nm to 20 nm and a volume average particle diameter of 50 nm to 20 μm. An ink jet recording medium having an ink receiving layer on a support in which a mass ratio of the porous silica to the total amount of the vapor phase silica and the porous silica is less than 50% by mass is known (for example, patents). Reference 1). In Patent Document 1, for example, an ink receiving layer including a polyvinyl alcohol resin as a binder resin, vapor phase silica and a porous silica material is disclosed as an example. In this example, about 170 parts by mass of the vapor phase silica and the porous silica are used with respect to 100 parts by mass of the polyvinyl alcohol resin. As described above, the ink receiving layer described in the cited document 1 has a problem that a considerable amount of silica is stepped on the binder resin, and as a result, the ink receiving layer becomes clouded by the silica. Therefore, there is a demand for an inkjet recording medium in which the ink receiving layer is not clouded.

JP 2011-011520 A

  An object of the present invention is to provide an ink jet recording medium that does not become cloudy and can obtain a good image.

  As a result of intensive studies, the present inventors have found that the use of porous silica particles obtained by a specific production method makes it possible to receive ink that does not easily bleed out of ink jet without using gas phase method silica as in Reference 1. The layer is obtained, and the porous silica particles obtained by a specific production method are segregated on the surface of the ink receiving layer. The inventors have found that the receiving layer does not cause turbidity and have completed the present invention.

  That is, the present invention provides an ink jet recording medium having an ink receiving layer containing porous silica particles on a support, wherein the porous silica particles comprise a mixed liquid (liquid A) containing tetraalkoxysilane, alkylamine and alcohol. In addition to a liquid mixture (liquid B) containing ammonia, alcohol and water, a method comprising hydrolyzing and condensing tetraalkoxysilane to obtain silica particles, and a step of removing alkylamine from the silica particles The present invention provides an ink jet recording medium obtained by the method described above.

  According to the present invention, it is possible to provide an ink jet recording medium that is excellent in transparency and in which the occurrence of ink bleeding is suppressed.

  The ink jet recording medium of the present invention has one or two or more ink receiving layers on a support, and the ink receiving layer is provided with a layer containing porous silica particles to be described later. It is.

  The ink receiving layer includes at least porous silica particles described later, preferably includes a water-soluble resin, a mordant (water-soluble metal compound, nitrogen-containing organic cationic polymer, etc.), and further, a crosslinking agent as necessary. Other components can be used.

  The porous silica particles used in the present invention are prepared by the method for producing porous silica particles of the present invention by mixing a mixed liquid (A liquid) containing tetraalkoxysilane, alkylamine and alcohol with a mixed liquid containing ammonia, alcohol and water ( In addition to (Liquid B), the tetraalkoxysilane is hydrolyzed and condensed to produce silica particles, and the silica particles are fired.

  Examples of the tetraalkoxysilane that is a constituent component of the liquid A and is a raw material for the porous silica particles include tetramethoxysilane, tetraethoxysilane, and tetrapropoxysilane. Among these, tetramethoxysilane is preferable because of its high reactivity. These tetraalkoxysilanes can be used alone or in combination of two or more.

  Alkylamine, which is a component of the liquid A, functions as a so-called template for creating pores on the surface of the silica particles, and therefore the number, size, and shape of the pores can be controlled by the type and amount of addition. Alkylamine also acts as a catalyst for hydrolysis and condensation reaction of tetraalkoxysilane together with ammonia described later. As the alkylamine, an amine compound having an alkyl group having 6 to 18 carbon atoms has good solubility in alcohol as a solvent of the liquid A or the liquid B, and porous silica fine particles having a particle diameter of, for example, 100 to 250 nm are used. It is preferable because it is easy to obtain. Specific examples of the amine compound having an alkyl group having 6 to 18 carbon atoms include octylamine, decylamine, laurylamine, tetradecylamine, oleylamine and the like. These alkylamines can be used alone or in combination of two or more.

  In order to increase the number of pores of the silica particles, for example, the ratio of tetraalkoxysilane and alkylamine (tetraalkoxysilane / alkylamine) described later may be decreased. In order to increase the pore size of the silica particles, for example, an alkylamine having a large number of carbon atoms may be used.

  Alcohol, which is a constituent component of the liquid A, works as a solvent, and has an effect of dissolving the alkylamine and facilitating obtaining a liquid A that is uniformly mixed. As alcohol, what is miscible with water is preferable. Furthermore, from the viewpoint of preventing the reaction system from becoming complicated due to the exchange reaction between the alkoxysilane and the alcohol, those having the same number of carbon atoms as the alkoxy sites of the tetraalkoxysilane used are particularly preferred. Specific examples include methanol, ethanol, propanol and the like.

  The ratio of tetraalkoxysilane and alkylamine in solution A [tetraalkoxysilane / alkylamine] has a molar ratio of 1 / 0.05 to 1/5, and has pores on the surface, And it is preferable in order to obtain the particle | grains whose primary particle is spherical, 1 / 0.1-1 / 3.0 are more preferable by molar ratio, and 1 / 0.1-1 / 2.0 are still more preferable by molar ratio.

  Moreover, as content of the tetraalkoxysilane in A liquid, 10-60 mass parts in 100 mass parts of A liquid can be manufactured from many yields, and 25-45 mass parts is more preferable.

  Ammonia, which is a component of liquid B, acts as a catalyst for the hydrolysis and condensation reaction of tetraalkoxysilane. The ammonia to be used may be added as aqueous ammonia or ammonia may be introduced into the reaction solution in the form of a gas. However, it is preferable to use aqueous ammonia because the amount used can be easily controlled.

  As the alcohol that is a component of the liquid B, for example, the alcohol used for preparing the liquid A can be used. The alcohol used may be the same as the alcohol used for preparing the liquid A, or may be different. Moreover, you may use by only 1 type and may use 2 or more types together.

  As water used as a solvent in the production method of the present invention as a component of the liquid B, it is preferable to use pure water in order to avoid impurities from entering the reaction system as much as possible.

  The ratio of ammonia to water in the liquid B [ammonia / water] is a particle having a pore on the surface and primary particles having a spherical shape, having a molar ratio in the range of 1/1 to 1/20. It is preferable to obtain Furthermore, since the reaction operation can be facilitated using aqueous ammonia, the molar ratio of ammonia to water is more preferably from 1 / 2.5 to 1/20.

  The mass of water in the B liquid is preferably 1 to 40 parts by mass and more preferably 2 to 30 parts by mass with respect to 100 parts by mass of the B liquid because the particle diameter of the porous silica fine particles can be easily controlled.

  In the method for producing porous silica particles having pores on the surface of the present invention, the liquid A is added to the liquid B, and tetraalkoxysilane is hydrolyzed and condensed to obtain silica particles (hereinafter abbreviated as step 1). And a step of removing alkylamine from the silica particles (hereinafter abbreviated as step 2).

  The above process will be described in detail below. Step 1 is a step of forming silica particles by hydrolyzing and condensing tetraalkoxysilane. When mixing liquid A and liquid B, the amount of ammonia acting as a catalyst for the hydrolysis and condensation reaction of tetraalkoxysilane is such that the pH of the liquid mixture (reaction system) of liquid A and liquid B is 8 to 12. It is preferable to mix the liquid A and the liquid B so that the amount is in the range because it is easy to obtain particles whose primary particles are spherical, and the liquids A and B so that the pH is in the range of 9 to 11. More preferably, the liquids are mixed.

  In order to add the A liquid to the B liquid, for example, the A liquid may be added dropwise from the top of the container containing the B liquid, or a conduit nozzle is placed in the container containing the B liquid. Liquid A may be added to liquid B by flowing liquid A out of the conduit nozzle. Moreover, when adding A liquid to B liquid, you may inject A liquid there, stirring B liquid.

  The temperature at the time of mixing the liquid A and the liquid B is preferably in the range of 5 to 80 ° C. in order to obtain solubility of the reaction raw material in the reaction system and particles in which the primary particles are spherical.

  The injection time of the liquid A into the liquid B is preferably in the range of 0 to 240 minutes, and more preferably in the range of 30 to 150 minutes. Here, 0 minutes represents that the A liquid is charged into the B liquid all at once. Further, after the injection of the liquid A, it is preferable that the reaction is further stirred for 10 minutes or more in a temperature range of 5 to 80 ° C. By this step 1, silica particles that are the basis of the porous silica particles are obtained.

  In step 1, liquid A is added to liquid B, and then a mixed liquid (A 'liquid) containing tetraalkoxysilane and alcohol is further added, so that other compounds, for example, solvent and resin enter the pores of the resin. Porous silica particles that can be suppressed are obtained. The A ′ solution may be added immediately after adding the A solution to the B solution, or may be added after the A solution is added to the B solution and then allowed to stand or stir.

  In Step 2, the alkylamine is removed from the silica particles obtained in Step 1 above. Examples of the method for removing the alkylamine include a method of washing the silica particles with an acid, a method of spraying the silica particles to a high temperature, and a method of firing the silica particles.

  When removing the alkylamine from the silica particles, the silica particles may be washed in advance. As a method for washing the silica particles, for example, first, the silica particles are centrifuged from the reaction solution obtained in step 1 to take out the silica particles. Alcohol is added to the silica particles and stirred to form a suspension, and the suspension is centrifuged again to extract the silica particles. By performing this step several times, the silica particles are washed with alcohol. The alcohol used at this time is preferably the same type as the alcohol used in the preparation of the liquid A and liquid B. In addition, as a method of taking out silica particles from a reaction solution and alcohol suspension, it is not restricted to centrifugation, For example, you may use ultrafiltration. Moreover, you may implement an washing | cleaning process continuously using an ultrafiltration apparatus.

  Examples of the acid used in the method for washing the silica particles with an acid include hydrochloric acid, nitric acid, sulfuric acid, and acetic acid. Among these acids, inorganic acids are preferable because the neutralized salt is water-soluble.

  When the silica particles are washed with an acid, it is preferably carried out in the presence of alcohol in addition to water. In this case, the alcohol used may be the same type as the alcohol used in the liquid A and liquid B. Furthermore, the extraction of the alkylamine is preferably performed by heating, and the temperature range is preferably near the boiling point of the alcohol used because of high extraction efficiency.

  In order to spray the silica particles at a high temperature, for example, a commercially available spray dryer that can spray the silica particles in an atmosphere of about 270 to 800 ° C. may be used. Here, when spraying the silica particles at a high temperature, the silica particles may be washed with the alcohol or acid.

  In the method of firing the silica particles, the silica particles may be washed with the alcohol or acid.

  If necessary, the drying temperature for drying the silica fine particles after the washing is preferably in the range of 60 to 150 ° C, more preferably in the range of 80 to 130 ° C.

  The dried silica particles are baked to remove all organic substances remaining on the silica particles. Thereby, the alkylamine used as a template is removed. As the conditions for the firing step, the firing temperature is preferably in the range of 400 to 1,000 ° C, more preferably in the range of 500 to 800 ° C. Moreover, as baking time, it is preferable that it is 30 minutes or more, and it is more preferable that it is 1 hour or more. By performing this firing step, all the organic matter remaining on the silica particles can be removed, so that porous silica having pores on the surface of the silica particles can be obtained.

  If the particles are aggregated after firing, it is preferably pulverized. Examples of the pulverizer used for pulverization include a ball mill, a colloid mill, a conical mill, a disk mill, an edge mill, a milling mill, a hammer mill, a mortar, a pellet mill, a jet mill, a vertical axis impactor (VSI) mill, a wheelie mill, and a roller mill. It is done.

  Further, since the silica particles can be prevented from self-aggregation and dispersibility in an organic solvent or resin is improved, the hydroxyl group of the silanol group present on the surface of the porous silica particles obtained after the baking step is a surface treatment agent. It is preferable to replace the surface with a hydrophobic group. As a method for performing this surface treatment, for example, a method of immersing porous silica in a solution in which a surface treatment agent is dissolved in a solvent, and heating as necessary may be mentioned. Examples of the solvent used for the surface treatment include methanol, ethanol, isopropyl alcohol, benzene, toluene, xylene, N, N-dimethylformamide, hexamethyldisiloxane, and the like. Surface treatment agents used for surface modification include silane compounds and silazane compounds such as methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, and hexyl. Trimethoxysilane, hexyltriethoxysilane, decyltrimethoxysilane, trifluoropropyltrimethoxysilane, hexamethyldisiloxane, trimethylmethoxysilane, ethyltrimethoxysilane, trimethylethoxysilane, dimethyldiethoxysilane, hexamethyldisilazane, methoxy “Dow Corning 2634 Coating” (made by Toray Dow Corning Co., Ltd.), which is a perfluoropolyether having a silane terminal, ethoxy A perfluoropolyether having a run ends (manufactured by Solvay Solexis) "Fluorolink S10", and the like. In particular, by performing a surface treatment with the silazane compound, porous silica particles whose surface is modified with the silazane compound can be obtained. Specifically, after the step 2 (step of removing the alkylamine from the silica particles), the surface is modified with the silazane compound by including in the production method of the present invention the step of modifying the surface of the resulting porous silica particles. Porous silica particles can be obtained. As the silazane compound used here, hexamethyldisilazane is preferable.

  When the surface of the porous silica particles is modified with a silazane compound, it is preferable to use a catalyst. Examples of the catalyst include inorganic acids such as hydrochloric acid, sulfuric acid and nitric acid; organic acids such as oxalic acid, acetic acid, formic acid, methanesulfonic acid and toluenesulfonic acid; inorganic bases such as sodium hydroxide, potassium hydroxide and ammonia; triethylamine And organic bases such as pyridine; metal alkoxides such as triisopropoxyaluminum and tetrabutoxyzirconium. Among these, acid catalysts (inorganic acids and organic acids) are used because the production stability and storage stability of the dispersion of porous silica particles are improved. Inorganic acids such as hydrochloric acid and sulfuric acid, and organic acids such as methanesulfonic acid, oxalic acid, phthalic acid, malonic acid, and acetic acid are preferable, and acetic acid is particularly preferable.

  Examples of the method for modifying the surface of the porous silica particles include a method in which the porous silica is immersed in a solution in which a surface modifier is dissolved in a solvent and heated as necessary. Examples of the solvent used for this surface modification include methanol, ethanol, isopropyl alcohol, benzene, toluene, xylene, N, N-dimethylformamide, acetone, methyl ethyl ketone, and methyl isobutyl ketone.

  The amount of the surface modifier used for the surface modification of the porous silica particles is such that the porous silica particles do not agglomerate and are stable as primary particles. On the other hand, the range of the surface modifier is preferably 0.3 to 60 parts by mass, but more preferably 0.5 to 50 parts by mass.

  Furthermore, it is preferable to pulverize the agglomerated porous silica particles at the same time as the above surface modification to obtain a dispersion in a primary particle state.

  By passing through the above steps 1 and 2, porous silica particles can be obtained. The particle shape, average particle diameter, average pore diameter and specific surface area of the obtained porous silica particles can be measured by the following measuring method.

[Particle shape]
The particle shape can be confirmed by observation using a field emission scanning electron microscope (FE-SEM) (for example, “JSM6700” manufactured by JEOL Ltd.).

[Average particle size]
The average particle diameter can be confirmed by observation using a field emission scanning electron microscope (FE-SEM) (for example, “JSM6700” manufactured by JEOL Ltd.).

[Average pore diameter]
The average pore diameter can be measured using a pore distribution measuring device (for example, Shimadzu Corporation “ASAP2020”).

[Specific surface area]
The specific surface area can be measured by a BET method using a pore distribution measuring device (for example, Shimadzu Corporation “ASAP2020”).

By the measurement method described above, the particle shape, average particle diameter, average pore diameter, and specific surface area of the porous silica particles obtained by the method for producing porous silica particles of the present invention can be measured. As a feature of the method for producing porous silica particles of the present invention, porous silica particles having a substantially spherical appearance are obtained, and the average particle diameter is controlled by adjusting the amount of ammonia used as described above. In the range of 50 to 300 nm, preferably 100 to 250 nm can be obtained. Moreover, the average pore diameter and specific surface area of the porous silica particles can be controlled by the type and amount of alkylamine used, and the average pore diameter is obtained in the range of 1 to 4 nm. In the range of 40 to 900 m ² / g.

  As content of the porous silica particle used by this invention, 0.05-3 mass parts is preferable with respect to 100 mass parts of water-soluble resin mentioned later, and 0.1-1.0 mass part is more preferable.

  The ink receiving layer in the invention preferably contains at least one water-soluble resin. Examples of water-soluble resins include polyvinyl alcohol resins that are resins having a hydroxy group as a hydrophilic structural unit [polyvinyl alcohol (PVA), acetoacetyl-modified polyvinyl alcohol, cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, silanol-modified polyvinyl. Alcohol, polyvinyl acetal, etc.], cellulose resins [methyl cellulose (MC), ethyl cellulose (EC), hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), hydroxypropyl cellulose (HPC), hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, etc.], Chitins, chitosans, starches, resins with ether bonds [polyethylene oxide (PEO), polyp Pyrene oxide (PPO), polyethylene glycol (PEG), poly ether (PVE)], and resins having carbamoyl groups [polyacrylamide (PAAM), polyvinyl pyrrolidone (PVP), polyacrylic acid hydrazide, etc.] and the like.

  Moreover, the polyacrylic acid salt which has a carboxyl group as a dissociable group, maleic acid resin, alginate, gelatins, etc. can be mentioned.

  Among the above, the water-soluble resin is preferably at least one selected from polyvinyl alcohol resins, cellulose resins, resins having an ether bond, resins having a carbamoyl group, resins having a carboxyl group, and gelatins. Polyvinyl alcohol (PVA) resin is preferable.

  Examples of the polyvinyl alcohol-based resin include, for example, Japanese Patent Publication No. 4-52786, Japanese Patent Publication No. 5-67432, Japanese Patent Publication No. 7-29479, Japanese Patent No. 2537827, Japanese Patent Publication No. 7-57553, Japanese Patent No. 2502998, Japanese Patent Nos. 3053231, 63-176173, 2604367, 7-276787, 9-207425, 11-58941, 2000-135858, 2001-2001 205924, JP 2001-287444, JP 62-278080, JP 9-39373, JP 2750433, JP 2000-158801, JP 2001-213045, JP 2001-328345. JP, 8-324105, JP 11-348417, JP JP-A-8-181687, JP-A-10-259213, JP-A-2001-72711, JP-A-2002-103805, JP-A-2000-63427, JP-A-2002-308928, JP-A-2001-205919, JP-A-2002. -264489 etc. are mentioned.

  Examples of water-soluble resins other than polyvinyl alcohol resins include compounds described in JP-A-11-165461, [0011] to [0012], JP-A-2001-205919, and JP-A-2002-264489. The described compounds are also included.

  These water-soluble resins may be used alone or in combination of two or more.

  The water-soluble resin and the inorganic fine particles, which mainly constitute the ink receiving layer in the invention, may be a single material or a mixed system of a plurality of materials.

  From the viewpoint of maintaining the transparency of the ink receiving layer, the type of water-soluble resin combined with the porous silica particles is important. As the water-soluble resin, a polyvinyl alcohol resin is preferable. Among them, a polyvinyl alcohol resin having a saponification degree of 70 to 100% is more preferable, and a polyvinyl alcohol resin having a saponification degree of 80 to 99.5% is particularly preferable.

  The polyvinyl alcohol-based resin has a hydroxyl group in its structural unit, and since this hydroxyl group and the surface silanol group of the silica fine particle form a hydrogen bond, a three-dimensional network having a secondary particle of the silica fine particle as a network chain unit. It becomes easy to form a structure. By forming this three-dimensional network structure, it is considered that a porous ink receiving layer having a high porosity and sufficient strength is formed. In ink jet recording, the porous ink receiving layer obtained as described above can absorb ink rapidly by a capillary phenomenon, and can form dots with good roundness without ink bleeding.

  In addition, the polyvinyl alcohol resin may be used in combination with the other water-soluble resin. When the other water-soluble resin and the polyvinyl alcohol resin are used in combination, the content of the polyvinyl alcohol resin in the total water-soluble resin is preferably 50% by mass or more, and more preferably 70% by mass or more.

  The ink receiving layer may contain a mordant. As the mordant, a nitrogen-containing organic cationic polymer or a water-soluble metal compound can be used.

  The ink receiving layer preferably contains at least one nitrogen-containing organic cationic polymer from the viewpoint of further suppressing bleeding of the recorded image and from the viewpoint of dispersing silica.

  The nitrogen-containing organic cationic polymer is not particularly limited, but a polymer having a primary to tertiary amino group or a quaternary ammonium base is preferable. The nitrogen-containing organic cationic polymer is a homopolymer of a monomer having a primary to tertiary amino group and a salt thereof, or a monomer having a quaternary ammonium base (nitrogen-containing organic cationic monomer). Conjugated diene systems such as nitrogen-containing organic cation polymers, styrene-butadiene copolymers, methyl methacrylate-butadiene copolymers obtained as copolymers or condensation polymers of the nitrogen-containing organic cation monomers and other monomers Copolymers; Acrylic polymers such as acrylic acid and methacrylic acid ester polymers or copolymers, acrylic acid and methacrylic acid polymers or copolymers; styrene-acrylic acid ester copolymers, styrene-methacrylic acid Styrene-acrylic polymers such as acid ester copolymers; Vinyl resins such as ethylene vinyl acetate copolymers System polymer; the urethane polymer or the like having a urethane bond include a nitrogen-containing organic cation polymers obtained by cationizing modified with a compound containing a cationic group.

  Examples of the other monomer that can be copolymerized (or polycondensed) with the nitrogen-containing organic cation monomer include primary to tertiary amino groups and salts thereof, or basic such as quaternary ammonium base. Or the monomer which does not contain a cationic part, does not show interaction with the dye in an inkjet ink, or interaction is substantially small is mentioned. For example, (meth) acrylic acid alkyl ester; (meth) acrylic acid cycloalkyl ester such as cyclohexyl (meth) acrylic acid; (meth) acrylic acid aryl ester such as phenyl (meth) acrylate; benzyl (meth) acrylic acid Aralkyl esters of styrene; vinyl aromatics such as styrene, vinyl toluene and α-methyl styrene; vinyl esters such as vinyl acetate, vinyl propionate and vinyl versatate; allyl esters such as allyl acetate; vinylidene chloride, vinyl chloride, etc. Halogen-containing monomers, vinyl cyanides such as (meth) acrylonitrile, olefins such as ethylene and propylene, and the like.

  The (meth) acrylic acid alkyl ester is preferably a (meth) acrylic acid alkyl ester having 1 to 18 carbon atoms in the alkyl moiety, specifically, for example, methyl (meth) acrylate or ethyl (meth) acrylate. Propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, and the like.

  As a monomer constituting the urethane polymer, a polyvalent isocyanate compound having two or more isocyanate groups (for example, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, hydrogenated xylylene diisocyanate) , Hydrogenated 4,4′-diphenylmethane diisocyanate, etc.) and a compound that can react with an isocyanate group to form a urethane bond (for example, glycerin, 1,6-hexanediol, triethanolamine, polypropylene glycol, polyethylene glycol, etc. Polyol compounds; acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, fumaric acid, ethylenediamine, propylenediamine, diethylenetriamine, Ethylenediamine, phenylenediamines, amines such as tolylenediamine, hydrazine and the like).

  Furthermore, examples of the compound for introducing a cationic group into a copolymer or condensate having no cationic group include alkyl halides and methylsulfuric acid.

  Among the nitrogen-containing organic cationic polymers, from the viewpoint of suppressing bleeding, cationic polyurethanes and cationic polyacrylates described in JP-A No. 2004-167784 are preferable, and cationic polyurethanes are more preferable. As commercial products of cationic polyurethane, for example, “Superflex 650”, “F-8564D”, “F-8570D” manufactured by Daiichi Kogyo Seiyaku Co., Ltd., “Neofix IJ-” manufactured by Nikka Chemical Co., Ltd. 150 "and the like.

  From the viewpoint of particle dispersion, polydiallyldimethylammonium chloride and polymethacryloyloxyethyl-β-hydroxyethyldimethylammonium chloride derivatives are preferable, and polydiallyldimethylammonium chloride is more preferable. Examples of commercially available products include “Charol DC902P” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

  The ink receiving layer preferably contains at least one water-soluble metal compound.

  Examples of the water-soluble metal compound include water-soluble salts of metals selected from calcium, magnesium, barium, manganese, copper, cobalt, nickel, aluminum, iron, zinc, zirconium, chromium, tungsten, and molybdenum. For example, magnesium salts include magnesium acetate, magnesium oxalate, magnesium sulfate, magnesium chloride hexahydrate, and magnesium citrate nonahydrate. Of these, magnesium chloride hexahydrate is preferred.

  The “water-soluble” of the water-soluble metal compound means that 1% by mass or more dissolves in water at 20 ° C.

  Among the water-soluble metal compounds, a trivalent or higher valent metal compound is preferable, an aluminum compound or a compound containing a Group 4A metal (for example, zirconium or titanium) in the periodic table is preferable, and an aluminum compound is more preferable. Particularly preferred is a water-soluble aluminum compound.

  Examples of the water-soluble aluminum compound include aluminum chloride or a hydrate thereof (eg, aluminum chloride hexahydrate), aluminum sulfate or a hydrate thereof, ammonium alum, aluminum sulfite, aluminum thiosulfate, aluminum nitrate nine water Japanese hydrates, aluminum acetate, aluminum lactate, basic aluminum thioglycolate and the like are known. Furthermore, basic polyaluminum hydroxide compounds (hereinafter also referred to as “basic polyaluminum chloride” and “polyaluminum chloride”), which are inorganic aluminum-containing cationic polymers, are known and preferably used. The basic polyaluminum hydroxide compound is represented by the following formula 1, formula 2 or formula 3, for example, [Al6 (OH) 15] 3+, [Al8 (OH) 20] 4+, [Al13 (OH ) 34] 5+, [Al21 (OH) 60] 3+, and the like, which are water-soluble polyaluminum hydroxides that stably contain basic and high-molecular polynuclear condensed ions.

[Al ₂ (OH) _n Cl _6-n ] _m (Formula 1)
[Al (OH) ₃ ] _n AlCl ₃ (Formula 2)
Al _n (OH) _m Cl _(3n-m) [0 <m <3n] (Formula 3)
These are water treatment agents under the name of polyaluminum chloride (PAC) from Taki Chemical Co., Ltd., polyaluminum hydroxide (Paho) from Asada Chemical Co., Ltd., and HAP from Riken Green Co., Ltd. The name is -25, from Daimei Chemical Co., Ltd., the name of Alpha-In 83, and also from other manufacturers for the same purpose, various grades can be easily obtained.

  As the compound containing the Group 4A metal of the periodic table, a water-soluble compound containing titanium or zirconium is more preferable. Examples of the water-soluble metal compound containing titanium include titanium chloride, titanium sulfate, titanium tetrachloride, tetraisopropyl titanate, titanium acetylacetonate, and titanium lactate. Examples of the water-soluble metal compound containing zirconium include zirconium acetate, zirconyl acetate, zirconium chloride, hydroxy zirconium chloride, zirconium nitrate, zirconyl nitrate, basic zirconium carbonate, zirconium hydroxide, zirconium lactate, zirconyl lactate, zirconium carbonate / ammonium carbonate, Zirconium / potassium, zirconyl / ammonium carbonate, zirconyl / potassium carbonate, zirconium sulfate, zirconium fluoride, zirconyl sulfate, zirconyl fluoride, and the like.

  The content of the water-soluble metal compound (preferably a water-soluble aluminum compound) in the ink receiving layer is 0.1 with respect to the total amount of the vapor phase silica and the porous silica material in terms of image density and water resistance. 10 mass% is preferable, and 0.5-8 mass% is more preferable.

  The ink receiving layer can contain a sulfur compound from the viewpoint of further improving ozone resistance. As the sulfur compound, one or more selected from thioether compounds, thiourea compounds, disulfide compounds, sulfinic acid compounds, thiocyanic acid compounds, sulfur-containing heterocyclic compounds, and sulfoxide compounds are suitable. Can be used. Of the sulfur compounds, thioether compounds or sulfoxide compounds are preferred.

  Specific examples of the sulfur-based compound include compounds described in paragraph numbers [0024] to [0088] of JP-A-2008-246989.

  For example, when the ink receiving layer contains a thioether-based compound, this improves the storability of the image area (fading due to a trace gas such as ozone or nitrogen oxide in the air). As the thioether compound, a compound represented by the following general formula (A) is preferably used.

R < ₁ >-(S-R < ₃ >) m-S-R < ₂ > General formula (A)

In the general formula (A), R ₁ and R ₂ each independently represent a hydrogen atom, an alkyl group, or an aromatic group, and R ₁ and R ₂ may be the same or different and combine to form a ring. May be. In addition, at least one of R ₁ and R ₂ is an alkyl group or an aromatic group substituted with a hydrophilic group such as an amino group, an amide group, an ammonium group, a hydroxy group, a sulfo group, a carboxy group, an aminocarbonyl group, or an aminosulfonyl group. It is a group. R ₃ represents an alkylene group having an oxygen atom. m represents a positive number of 0 to 10, and when m is 1 or more, at least one sulfur atom bonded to R ₃ may be a sulfonyl group.

  Examples of the thioether compounds include 3-thia-1,5-heptanediol, 4-thia-1,7-pentanediol, 3,6-dithia-1,8-octanediol, 3,6,9- Examples include trithia-1,11-undecanediol, 3,9-dithia-6-oxa-1,11-undecanediol, methylenebis (thioglycolic acid), bis [2- (2-hydroxyethylthio) ethyl] sulfone, and the like. It is done.

  The content of the sulfur-based compound in the ink receiving layer is preferably in the range of 0.5 to 50% by mass, more preferably in the range of 1 to 40% by mass with respect to the total solid content of the ink receiving layer.

  The ink receiving layer in the invention preferably contains at least one crosslinking agent from the viewpoint of crosslinking the water-soluble resin. In the present invention, the ink receiving layer is preferably a porous layer cured by a crosslinking reaction between a crosslinking agent and a water-soluble resin.

  Boron compounds are preferred for crosslinking the water-soluble resin, particularly polyvinyl alcohol.

Examples of the boron compound include borax, boric acid, borate (for example, orthoborate, InBO ₃ , ScBO ₃ , YBO ₃ , LaBO ₃ , Mg ₃ (BO ₃ ) ₂ , Co ₃ (BO ₃ ) ₂ , diboric acid. Salt (eg, Mg ₂ B ₂ O ₅ , Co ₂ B ₂ O ₅ ), metaborate (eg, LiBO ₂ , Ca (BO ₂ ) ₂ , NaBO ₂ , KBO ₂ ), tetraborate (eg, Na ₂ B ₄ O ₇ · 10H ₂ O), pentaborate (for example, KB ₅ O ₈ · 4H ₂ O, Ca ₂ B ₆ O ₁₁ · 7H ₂ O, CsB ₅ O ₅ ), etc. Borax, boric acid and borates are preferred, and boric acid is particularly preferred in that a crosslinking reaction can be promptly caused.

  Moreover, the following compounds other than a boron compound can also be used as a crosslinking agent of water-soluble resin. For example, aldehyde compounds such as formaldehyde, glyoxal and glutaraldehyde; ketone compounds such as diacetyl and cyclopentanedione; bis (2-chloroethylurea) -2-hydroxy-4,6-dichloro-1,3,5- Active halogen compounds such as triazine and 2,4-dichloro-6-S-triazine sodium salt; divinylsulfonic acid, 1,3-vinylsulfonyl-2-propanol, N, N′-ethylenebis (vinylsulfonylacetamide) ), Active vinyl compounds such as 1,3,5-triacryloyl-hexahydro-S-triazine; N-methylol compounds such as dimethylolurea and methyloldimethylhydantoin; melamine resins (for example, methylolmelamine, alkylated methylolmelamine) Epoxy resin; 1,6- Isocyanate compounds such as hexamethylene diisocyanate; Aziridine compounds described in US Pat. Nos. 3,017,280 and 2998611; Carboximide compounds described in US Pat. No. 3,100,704; Epoxys such as glycerol triglycidyl ether Compounds; ethyleneimino compounds such as 1,6-hexamethylene-N, N′-bisethyleneurea; halogenated carboxaldehyde compounds such as mucochloric acid and mucophenoxycyclolic acid; dioxane such as 2,3-dihydroxydioxane Compounds: titanium lactate, aluminum sulfate, chromium alum, potash alum, metal-containing compounds such as zirconyl acetate and chromium acetate, polyamine compounds such as tetraethylenepentamine, hydrazide compounds such as adipic acid dihydrazide, oxazo A low molecule or polymer containing two or more phosphorus groups can be used. A crosslinking agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  1-50 mass% is preferable with respect to water-soluble resin, and, as for content of a crosslinking agent, 5-40 mass% is more preferable.

  The ink receiving layer may contain other components such as a mordant other than the nitrogen-containing organic cationic polymer and the water-soluble polyvalent metal salt, and various surfactants. Other components include those described in paragraphs [0088] to [0117] of JP-A-2005-14593, and components described in paragraphs [0138] to [0155] of JP-A-2006-321176. Etc. can be appropriately selected and used.

  As the support used in the present invention, either a transparent support made of a transparent material such as plastic or an opaque support made of an opaque material such as paper can be used. In order to make use of the transparency of the ink receiving layer, it is preferable to use a transparent support or a highly glossy opaque support. Further, a read-only optical disk such as a CD-ROM or DVD-ROM, a write-once optical disk such as a CD-R or DVD-R, or a rewritable optical disk may be used as a support to provide an ink receiving layer on the label surface side. it can.

  The material that can be used as the transparent support is preferably a material that is transparent and can withstand radiant heat when used in an OHP or backlight display. Examples of the material include polyesters such as polyethylene terephthalate (PET); polysulfone, polyphenylene oxide, polyimide, polycarbonate, polyamide and the like. Of these, polyesters are preferable, and polyethylene terephthalate is particularly preferable.

  Although there is no restriction | limiting in particular as thickness of the said transparent support body, 50-200 micrometers is preferable at the point which is easy to handle.

  As the highly glossy opaque support, one having a glossiness of 40% or more on the surface on which the ink receiving layer is provided is preferable. The glossiness is a value determined according to the method described in JIS P-8142 (75-degree specular gloss test method for paper and paperboard). Specifically, for example, high gloss paper support such as art paper, coated paper, cast coated paper, baryta paper used for silver salt photographic support, polyesters such as polyethylene terephthalate (PET), Nitrocellulose, cellulose acetate, cellulose acetates such as cellulose acetate butyrate, polysulfone, polyphenylene oxide, polyimide, polycarbonate, polyamide, and other plastic films are made opaque by adding white pigments (surface calendering is applied) A high-gloss film; or a polyolefin coating layer containing or not containing a white pigment on the surface of the above-mentioned various paper supports, the above-mentioned transparent support, or a high-gloss film containing a white pigment or the like. A provided support (eg both sides of the base paper Resin-coated paper coated with a resin layer of the olefin), and the like.

  A white pigment-containing foamed polyester film (for example, foamed PET containing polyolefin fine particles and forming voids by stretching) can also be suitably exemplified. Furthermore, resin-coated paper used for silver salt photographic printing paper is also suitable.

  Although there is no restriction | limiting in particular also about the thickness of the said opaque support body, 50-300 micrometers is preferable at the point of handleability.

  The surface of the support may be subjected to corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet irradiation treatment or the like in order to improve wettability and adhesion.

  Next, the base paper used for the register coat paper will be described in detail. As the base paper, wood pulp is used as a main raw material, and paper is made using synthetic pulp such as polypropylene or synthetic fiber such as nylon or polyester in addition to wood pulp as necessary. As the above-mentioned wood pulp, any of LBKP, LBSP, NBKP, NBSP, LDP, NDP, LUKP, NUKP can be used, but more LBKP, NBSP, LBSP, NDP, LDP with more short fibers are used. preferable.

  However, the ratio of LBSP and / or LDP is preferably 10% by mass or more and 70% by mass or less.

  The pulp is preferably a chemical pulp (sulfate pulp or sulfite pulp) with few impurities, and a pulp having a whiteness improved by bleaching is also useful.

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

  The freeness of the pulp used for papermaking is preferably 200 to 500 ml as defined by CSF, and the fiber length after beating is 24 mesh residual mass% and 42 mesh residual as defined in JIS P-8207. The sum of 30% and 70% by mass is preferable. In addition, it is preferable that the mass% of 4 mesh remainder is 20 mass% or less.

  The basis weight of the base paper is preferably 30 to 250 g, and particularly preferably 50 to 200 g. The thickness of the base paper is preferably 40 to 250 μm. The base paper can be given a high smoothness by calendering at the paper making stage or after paper making. The density of the base paper is generally 0.7 to 1.2 g / m 2 (JIS P-8118).

  The stiffness of the base paper is preferably 20 to 200 g under the conditions specified in JIS P-8143.

  A surface sizing agent may be applied to the surface of the base paper. As the surface sizing agent, a sizing agent similar to the size that can be added to the base paper can be used.

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

  Examples of the polyolefin coating layer that covers the front and back surfaces of the base paper include polyethylene. The polyethylene is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but other LLDPE, polypropylene and the like can also be used in part.

  In particular, the polyethylene layer on the side on which the ink receiving layer is formed is obtained by adding rutile or anatase type titanium oxide, fluorescent whitening agent, ultramarine to polyethylene, as is widely done in photographic paper. Those having improved whiteness and hue are preferred. Here, as a titanium oxide content, about 3-20 mass% is preferable with respect to polyethylene, and 4-13 mass% is more preferable. Although the thickness of a polyethylene layer does not have limitation in particular, 10-50 micrometers is suitable for both front and back layers. Further, an undercoat layer can be provided on the polyethylene layer in order to provide adhesion to the ink receiving layer. As the undercoat layer, aqueous polyester, gelatin and PVA are preferable. Moreover, as thickness of this undercoat layer, 0.01-5 micrometers is preferable.

  Polyethylene-coated paper can be used as glossy paper, or when it is melt-extruded onto the surface of the base paper and coated, the matte surface or silky surface that can be obtained with ordinary photographic printing paper by so-called molding Can also be used.

  A back coat layer can be provided on the support, and the components that can be added to the back coat layer include white pigments, aqueous binders, and other components (eg, antifoaming agents, antifoaming agents, dyes, fluorescent whitening). Agents, preservatives, water-proofing agents, etc.).

  The ink jet recording medium in the invention may further have an ink solvent absorption layer, an intermediate layer, a protective layer and the like in addition to the ink receiving layer. Further, an undercoat layer may be provided on the support for the purpose of improving the adhesion between the ink receiving layer and the support and appropriately adjusting the electric resistance value.

  The ink receiving layer can be suitably formed by the following first and second modes. The first form of forming the ink receiving layer includes a step of applying a first liquid containing at least porous silica particles on a substrate to form a coating layer, and (1) ) At the same time as applying the first liquid, or (2) During the drying of the coating layer formed by applying the first liquid, and before the coating layer exhibits reduced-rate drying. And a step of applying a second liquid containing a basic compound and crosslinking and curing the coating layer to form an ink receiving layer in which the coating layer is crosslinked and cured.

  The second form of forming the ink-receiving layer includes a step of applying a first liquid containing porous silica particles on a substrate to form a coating layer, and the formed coating layer. In this embodiment, the ink receiving layer is formed by providing a step of cooling so as to lower by 5 ° C. or more with respect to the temperature of the first liquid at the time of coating and a step of drying the cooled coating layer.

  The first embodiment and the second embodiment include a step of forming a coating layer by applying a first liquid containing porous silica particles on a substrate (hereinafter also referred to as a “coating layer forming step”). Have. In the case of forming a two-layer ink-receiving layer, the coating layer forming step includes, as the first liquid, a first coating liquid containing porous silica particles and, if necessary, a water-soluble resin on the support, A second coating liquid containing porous silica particles (preferably, the ratio of the porous silica particles to the total mass of the coating liquid is 20% by mass or less) is applied in order from the support side to form a coating layer. Also good.

Application | coating of a 1st liquid can be performed using well-known coating apparatuses, such as an extrusion die coater, an air doctor coater, a bread coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, a bar coater, for example. The wet coating amount of the first solution is preferably _{50~200ml / m 2, 75~150ml / m} 2 is more preferable. Moreover, as a solid content application quantity of 1st liquid, 5-25 g / m < ₂ > is preferable and 10-18 g / m < ₂ > is more preferable.

  The first liquid can contain other components such as a water-soluble resin, a crosslinking agent, a mordant, a dispersant, and a surfactant. Moreover, in application | coating of a 1st liquid, it is also preferable to apply, after carrying out in-line mixing of the liquid containing water-soluble polyvalent metal salt (preferably basic polyaluminum chloride compound) as stated above.

  The first liquid is preferably acidic, and the pH is preferably 5.0 or less, more preferably 4.5 or less, and even more preferably 4.0 or less. When the pH of the first liquid is 5.0 or less, for example, the crosslinking reaction of the water-soluble resin by the crosslinking agent (particularly the boron compound) in the first liquid can be more sufficiently suppressed.

  The first liquid containing porous silica particles can be prepared, for example, as follows. That is, porous silica particles and a dispersant are added to water (for example, 10 to 20% by mass of porous silica particles in water), and a high-speed rotating wet colloid mill (for example, “M Technique Co., Ltd.” “ For example, 10000 rpm (preferably 5000 to 20000 rpm) under high speed rotation conditions, for example, for 20 minutes (preferably 10 to 30 minutes), followed by crosslinking agent (for example boric acid) and polyvinyl Add an alcohol (PVA) aqueous solution (for example, PVA having a mass about 1/3 of the above-mentioned vapor phase silica), and then add a water-soluble polyvalent metal salt (for example, basic polyaluminum hydroxide compound). Thus, it can be prepared by dispersing under the same rotation conditions as described above. The water-soluble polyvalent metal salt may be added by in-line mixing immediately before coating.

  Moreover, a liquid-liquid collision type disperser (for example, an optimizer manufactured by Sugino Machine Co., Ltd.) can also be used for the above dispersion.

  The obtained coating liquid is in a uniform sol state, and a porous ink receiving layer having a three-dimensional network structure can be formed by applying the coating liquid onto a substrate by the following coating method and drying it.

  In addition, the preparation of an aqueous dispersion composed of porous silica particles and a dispersant may be carried out by preparing an aqueous dispersion of porous silica particles in advance and adding the aqueous dispersion to an aqueous dispersant solution. The aqueous solution may be added to the aqueous dispersion of porous silica particles, or may be mixed at the same time. Further, the porous silica particles may be added to the aqueous dispersant solution as described above in the form of powder, not as an aqueous dispersion.

  After mixing said porous silica particle and a dispersing agent, an aqueous dispersion can be obtained by refine | pulverizing this mixed liquid using a disperser. As a disperser used for obtaining the aqueous dispersion, various types of conventionally known dispersers such as a high-speed rotary disperser, a medium agitating disperser (ball mill, sand mill, etc.), an ultrasonic disperser, a colloid mill disperser, and a high pressure disperser. Although a disperser can be used, a stirrer-type disperser, a colloid mill disperser, or a high-pressure disperser is preferable from the viewpoint of efficiently dispersing the formed fine particles.

  As the solvent, water, an organic solvent, or a mixed solvent thereof can be used. Examples of the organic solvent that can be used for this coating include alcohols such as methanol, ethanol, n-propanol, i-propanol, and methoxypropanol, ketones such as acetone and methyl ethyl ketone, tetrahydrofuran, acetonitrile, ethyl acetate, and toluene. It is done.

  In addition, a chaotic polymer can be used as the dispersant. Examples of the chaotic polymer include mordant examples described in paragraph numbers 0138 to 0148 of JP-A No. 2006-321176. It is also preferable to use a silane coupling agent as the dispersant. 0.1 mass%-30 mass% are preferable, and, as for the addition amount with respect to the porous silica particle of a dispersing agent, 1 mass%-10 mass% are still more preferable.

In the first embodiment, for the coating layer formed in the coating layer forming step,
(1) At the same time as the first liquid is applied, or
(2) During the drying of the coating layer formed by applying the first liquid, before the coating layer exhibits reduced-rate drying,
In any of the cases, there is a step of applying a second liquid containing a basic compound and crosslinking and curing the coating layer (hereinafter also referred to as “crosslinking and curing step”).

  As a method of applying the second liquid at the same time as “(1) Applying the first liquid”, a mode in which the first liquid and the second liquid are simultaneously applied in order from the substrate side is preferable. The simultaneous multilayer coating can be performed using a known coating apparatus such as an extrusion die coater or a curtain flow coater.

  The method of applying the second liquid before “(2) during the drying of the coating layer formed by applying the first liquid and before the coating layer exhibits reduced-rate drying” is disclosed in, for example, Japanese Patent Application Laid-Open No. 2005-2005. The so-called Wet-On-Wet method (WOW method) described in paragraph Nos. 0016 to 0037 of Japanese Patent No. 14593 is preferable. In the present invention, after the first liquid is applied to the substrate to form the coating layer, (i) the coating is performed during the drying of the formed coating layer and before the coating layer exhibits reduced-rate drying. A method of applying the second liquid on the layer, (ii) a method of spraying the second liquid on the coating layer by spraying, or (iii) immersing the substrate on which the coating layer is formed in the second liquid It can be done by the method to do.

  In the above (i), examples of the application method for applying the second liquid include curtain flow coaters, extrusion die coaters, air doctor coaters, bread coaters, rod coaters, knife coaters, squeeze coaters, reverse roll coaters, and bar coaters. A known coating method such as the above can be used. However, it is preferable to use a method in which the coater does not directly contact an already formed coating layer, such as an extrusion die coater, a curtain flow coater, a bar coater or the like.

  The term “before the coating layer comes to show reduced-rate drying” usually refers to a process for several minutes immediately after the application of the coating liquid for forming the ink receiving layer (first liquid). This shows the phenomenon of “constant rate drying” in which the content of the solvent (dispersion medium) in the applied layer decreases in proportion to time. About the time which shows this "constant rate drying", it describes in chemical engineering handbook (pages 707-712, Maruzen Co., Ltd. issue, October 25, 1980), for example.

  As a condition for drying until the coating layer exhibits reduced-rate drying, it is generally performed at 40 to 180 ° C. for 0.5 to 10 minutes (preferably 0.5 to 5 minutes). The drying time varies depending on the coating amount, but usually the above range is appropriate.

  Next, the said 2nd liquid in a bridge | crosslinking hardening process is demonstrated. The second liquid contains at least one basic compound. Examples of basic compounds include weak acid ammonium salts, weak acid alkali metal salts (eg, lithium carbonate, sodium carbonate, potassium carbonate, lithium acetate, sodium acetate, potassium acetate, etc.), weak acid alkaline earth metal salts (eg, , Magnesium carbonate, barium carbonate, magnesium acetate, barium acetate, etc.), hydroxyammonium, primary to tertiary amines (eg, triethylamine, tripropylamine, tributylamine, trihexylamine, dibutylamine, butylamine, etc.), primary to tertiary Aniline (eg, diethylaniline, dibutylaniline, ethylaniline, aniline, etc.), optionally substituted pyridine (eg, 2-aminopyridine, 3-aminopyridine, 4-aminopyridine, 4- (2-hydroxy) Ethyl) -ami Pyridine, and the like), and the like. In addition to the basic compound, other basic substances and / or salts thereof may be used in combination with the basic compound. Examples of other basic substances include ammonia, primary amines such as ethylamine and polyallylamine, secondary amines such as dimethylamine, tertiary amines such as N-ethyl-N-methylbutylamine, and alkali metals. And alkaline earth metal hydroxides.

  Of these, ammonium salts of weak acids are particularly preferred. The weak acid is an inorganic acid or an organic acid described in Chemical Handbook Fundamentals II (Maruzen Co., Ltd.) or the like and has an pKa of 2 or more. Examples of the weak acid ammonium salt include ammonium carbonate, ammonium hydrogen carbonate, ammonium borate, ammonium acetate, and ammonium carbamate. However, it is not limited to these. Among these, ammonium carbonate, ammonium hydrogen carbonate, and ammonium carbamate are preferable, and are effective in that ink bleeding can be reduced without remaining in the layer after drying. In addition, a basic compound can use 2 or more types together.

  As content in the 2nd liquid of the said basic compound (especially ammonium salt of weak acid), 0.5-10 mass% is preferable with respect to the total mass (a solvent is included) of 2nd liquid, More preferably, 1 ˜5 mass%. When the content of the basic compound (particularly the ammonium salt of the weak acid) is particularly in the above range, a sufficient degree of curing can be obtained, and the ammonia concentration becomes too high without impairing the working environment.

  A mode in which the second liquid contains at least one metal compound is preferable. As the metal compound contained in the second liquid, those that are stable under basic conditions can be used without limitation, and any of the water-soluble polyvalent metal salts, metal complex compounds, inorganic oligomers, or inorganic polymers described above can be used. There may be. For example, zirconium compounds and compounds listed as inorganic mordants in paragraph numbers 0100 to 0101 in JP-A-2005-14593 are suitable. Examples of the metal complex compound include metal complexes described in “Chemistry Review No. 32 (1981)” edited by the Chemical Society of Japan, “Coordination Chemistry Review”, Vol. 84, pages 85-277. (1988) and JP-A-2-182701, transition metal complexes containing a transition metal such as ruthenium can be used.

  Among the above, zirconium compounds and zinc compounds are preferable, and zirconium compounds are particularly preferable. Examples of the zirconium compound include ammonium zirconium carbonate, ammonium zirconium nitrate, potassium zirconium carbonate, ammonium zirconium citrate, zirconyl stearate, zirconyl octylate, zirconyl nitrate, zirconium oxychloride, and zirconium zirconium hydroxy chloride. Zirconium ammonium is preferred. In the second liquid, two or more metal compounds (preferably containing a zirconium compound) may be used in combination.

  As content in the 2nd liquid of the said metal compound (especially zirconium compound), 0.05-5 mass% is preferable with respect to the total mass (a solvent is included) of a 2nd liquid, More preferably, it is 0.1-0.1%. 2% by mass. By setting the content of the metal compound (especially zirconium compound) in the above range, the coating layer can be sufficiently hardened, and the mordanting ability is lowered and sufficient print density cannot be obtained or beading occurs. The concentration of the basic compound such as ammonia is not too high, and the working environment is not deteriorated. Two or more metal compounds can be used in combination, and when other mordant components to be described later are used in combination with a metal compound other than the metal compound, the total amount is within the above range and does not impair the effects of the present invention. It can be contained in a range.

  From the viewpoint of image density and ozone resistance, the second liquid preferably contains a magnesium salt as a metal compound. As the magnesium salt, magnesium chloride is particularly preferred. In this case, the addition amount of the magnesium salt is preferably 0.1 to 1% by mass, and more preferably 0.15 to 0.5% by mass with respect to the total mass of the second liquid.

 The second liquid may contain a crosslinking agent and other mordant components as necessary. The second liquid can be used as an alkaline solution to promote hardening of the coating layer, and is preferably adjusted to pH 7.1 or higher, more preferably pH 8.0 or higher, particularly preferably pH 9.0 or higher. is there. When the pH is 7.1 or more, the crosslinking reaction of the water-soluble resin that may be contained in the first liquid can be further promoted, and bronzing and cracking of the ink receiving layer can be more effectively suppressed.

  The second liquid is, for example, ion-exchanged water, a metal compound (for example, zirconia compound; for example, 1 to 5%) and a basic compound (for example, ammonium carbonate; for example, 1 to 5%), and paraffin as necessary. It can be prepared by adding toluenesulfonic acid (for example, 0.5 to 3%) and stirring sufficiently. In addition, all "%" of each composition means solid content mass%. Moreover, water, an organic solvent, or these mixed solvents can be used for the solvent used for preparation of a 2nd liquid. Examples of the organic solvent include alcohols such as methanol, ethanol, n-propanol, i-propanol and methoxypropanol, ketones such as acetone and methyl ethyl ketone, tetrahydrofuran, acetonitrile, ethyl acetate and toluene.

  On the other hand, the second liquid preferably has a small content of inorganic particles such as silica particles, and the content of the inorganic particles is preferably 50% by mass or less based on the total solid content of the second liquid. It is desirable not to include inorganic particles.

  In the second embodiment, the step of cooling the coating layer formed in the coating layer forming step so as to decrease by 5 ° C. or more with respect to the temperature of the first liquid at the time of coating (hereinafter referred to as “cooling step”). And a step of drying the cooled coating layer (hereinafter also referred to as “drying step”).

As a method for cooling the coating layer in the cooling step, a method of cooling the substrate on which the coating layer is formed in a cooling zone maintained at 0 to 10 ° C. for 5 to 30 seconds is preferable. In a cooling process, it is preferable to cool so that it may fall 0-10 degreeC, and it is more preferable to cool so that it may fall 0-5 degreeC or more. Here, the temperature of the coating layer is measured by measuring the temperature of the film surface.
Moreover, drying in a drying process can be performed by, for example, applying drying air. The temperature of the drying air at this time was evaluated at 30 to 80 ° C. Is preferred.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. In the examples, “part” and “%” are based on mass unless otherwise specified.

Production Example 1 (Production of porous silica particles)
A 500 mL four-necked flask equipped with a thermometer and stirring blades was charged with 213.2 g of methanol, 61.3 g of pure water and 27.4 g of 28% by mass ammonia water, and mixed uniformly by stirring (liquid B). Was kept at 20 ° C. In another container, 34.3 g of tetramethoxysilane (hereinafter abbreviated as “TMOS”), 45.1 g of methanol, and 6.5 g of octylamine were uniformly mixed (solution A). While keeping the inside of the flask at 20 ° C. and stirring, the liquid A was poured into the liquid B over 120 minutes. The reaction was continued at 20 ° C. for 60 minutes after the end of the injection of the liquid A. After completion of the reaction, the reaction solution was centrifuged at 10,000 rpm for 10 minutes, and then the supernatant was discarded and the precipitate was taken out.

200 g of methanol was added to the precipitate obtained above and mixed by stirring to obtain a suspension. This suspension was centrifuged at 10,000 rpm for 10 minutes, the supernatant was discarded, and the precipitate was washed with methanol. This methanol washing was repeated twice more. The precipitate thus obtained was dried at 120 ° C. for 6 hours to obtain a white powder. The obtained white powder was put into an electric furnace, heated from 25 ° C. to 600 ° C. at a rate of 2 ° C./min in an air atmosphere, and fired at 600 ° C. for 3 hours. The fired powder was cooled and then pulverized in a mortar to obtain 12.5 g of white porous silica particles (1). When the obtained porous silica particles were observed with a field emission scanning electron microscope (FE-SEM), the particle shape was spherical. Moreover, the average particle diameter of the obtained porous silica particles (1) was 101 nm, the average pore diameter was 1.5 nm, and the specific surface area by the BET method was 43 m ² / g.

Production Example 2 (same as above)
A 500 mL four-necked flask equipped with a thermometer and stirring blades was charged with 213.2 g of methanol, 61.3 g of pure water and 27.4 g of 28% by mass ammonia water, and mixed uniformly by stirring (liquid B). Was kept at 20 ° C. In another container, 34.3 g of TMOS, 45.1 g of methanol, and 39.3 g of decylamine were mixed uniformly (solution A). While keeping the inside of the flask at 20 ° C. and stirring, the liquid A was poured into the liquid B over 120 minutes. The reaction was continued at 20 ° C. for 60 minutes after the end of the injection of the liquid A. After completion of the reaction, the reaction solution was centrifuged at 10,000 rpm for 10 minutes, and then the supernatant was discarded and the precipitate was taken out.

200 g of methanol was added to the precipitate obtained above and mixed by stirring to obtain a suspension. This suspension was centrifuged at 10,000 rpm for 10 minutes, the supernatant was discarded, and the precipitate was washed with methanol. This methanol washing was repeated twice more. The precipitate thus obtained was dried at 120 ° C. for 6 hours to obtain a white powder. The obtained white powder was put into an electric furnace, heated from 25 ° C. to 600 ° C. at a rate of 2 ° C./min in an air atmosphere, and fired at 600 ° C. for 3 hours. After the fired powder was cooled, it was pulverized in a mortar to obtain 12.1 g of white porous silica particles (2). When the obtained porous silica particles were observed with a field emission scanning electron microscope (FE-SEM), the particle shape was spherical. The obtained porous silica particles (2) had an average particle size of 139 nm, an average pore size of 1.8 nm, and a specific surface area by BET method of 757 m ² / g.

Production Example 3 (same as above)
A 500 mL four-necked flask equipped with a thermometer and stirring blades was charged with 213.2 g of methanol, 61.3 g of pure water and 27.4 g of 28% by mass ammonia water, and mixed uniformly by stirring (liquid B). Was kept at 20 ° C. In another container, 34.3 g of TMOS, 45.1 g of methanol, and 9.3 g of laurylamine were uniformly mixed (solution A). While keeping the inside of the flask at 20 ° C., the liquid A was poured into the liquid B over 120 minutes. The reaction was continued at 20 ° C. for 60 minutes after the end of the injection of the liquid A. After completion of the reaction, the reaction solution was centrifuged at 10,000 rpm for 10 minutes, and then the supernatant was discarded and the precipitate was taken out.

To the precipitate obtained above, 200 g of methanol was added and mixed to obtain a suspension. This suspension was centrifuged at 10,000 rpm for 10 minutes, the supernatant was discarded, and the precipitate was washed with methanol. This methanol washing was repeated twice more. The precipitate thus obtained was dried at 120 ° C. for 6 hours to obtain a white powder. The obtained white powder was put into an electric furnace, heated from 25 ° C. to 600 ° C. at a rate of 2 ° C./min in an air atmosphere, and fired at 600 ° C. for 3 hours. The fired powder was cooled and then pulverized in a mortar to obtain 12.0 g of white porous silica particles (3). When the obtained porous silica particles were observed with a field emission scanning electron microscope (FE-SEM), the particle shape was spherical. Moreover, the average particle diameter of the obtained porous silica particles (3) was 122 nm, the average pore diameter was 1.8 nm, and the specific surface area by the BET method was 216 m ² / g.

Production Example 4 (same as above)
A 500 mL four-necked flask equipped with a thermometer and stirring blades was charged with 213.2 g of methanol, 61.3 g of pure water and 27.4 g of 28% by mass ammonia water, and mixed uniformly by stirring (liquid B). Was kept at 20 ° C. In another container, 34.3 g of TMOS, 45.1 g of methanol, and 13.4 g of oleylamine were uniformly mixed (solution A). While keeping the inside of the flask at 20 ° C. and stirring, the liquid A was poured into the liquid B over 120 minutes. The reaction was continued at 20 ° C. for 60 minutes after the end of the injection of the liquid A. After completion of the reaction, the reaction solution was centrifuged at 10,000 rpm for 10 minutes, and then the supernatant was discarded and the precipitate was taken out.

200 g of methanol was added to the precipitate obtained above and mixed by stirring to obtain a suspension. This suspension was centrifuged at 10,000 rpm for 10 minutes, the supernatant was discarded, and the precipitate was washed with methanol. This methanol washing was repeated twice more. The precipitate thus obtained was dried at 120 ° C. for 6 hours to obtain a white powder. The obtained white powder was put into an electric furnace, heated from 25 ° C. to 600 ° C. at a rate of 2 ° C./min in an air atmosphere, and fired at 600 ° C. for 3 hours. After the fired powder was cooled, it was pulverized in a mortar to obtain 12.6 g of white porous silica particles (4). When the obtained porous silica particles were observed with a field emission scanning electron microscope (FE-SEM), the particle shape was almost spherical. Moreover, the average particle diameter of the obtained porous silica particles (4) was 171 nm, the average pore diameter was 2.2 nm, and the specific surface area by the BET method was 583 m ² / g.

Production Example 5 (same as above)
A 500 mL four-necked flask equipped with a thermometer and stirring blades was charged with 213.2 g of ethanol, 77.9 g of pure water and 4.4 g of 28% by mass ammonia water, and mixed uniformly by stirring (liquid B). Was kept at 27 ° C. In another container, 28.6 g of tetraethoxysilane (hereinafter abbreviated as “TEOS”), 45.0 g of ethanol, and 13.4 g of laurylamine were mixed uniformly (liquid A). The liquid A was poured into the liquid B at a time while stirring the flask at 27 ° C. After completion of injection of solution A, the reaction was carried out at 27 ° C. for 5 hours. Subsequently, the temperature in the flask was raised to 65 ° C., and the reaction was further continued for 9 hours. After completion of the reaction, the reaction solution was centrifuged at 10,000 rpm for 10 minutes, and then the supernatant was discarded and the precipitate was taken out.

200 g of methanol was added to the precipitate obtained above and mixed by stirring to obtain a suspension. This suspension was centrifuged at 10,000 rpm for 10 minutes, the supernatant was discarded, and the precipitate was washed with methanol. This methanol washing was repeated twice more. The precipitate thus obtained was dried at 120 ° C. for 6 hours to obtain a white powder. The obtained white powder was put into an electric furnace, heated from 25 ° C. to 600 ° C. at a rate of 2 ° C./min in an air atmosphere, and fired at 600 ° C. for 3 hours. The fired powder was cooled and then ground in a mortar to obtain 12.0 g of white porous silica particles (5). When the obtained porous silica particles were observed with a field emission scanning electron microscope (FE-SEM), the particle shape was spherical. The obtained porous silica particles (5) had an average particle size of 118 nm, an average pore size of 1.8 nm, and a specific surface area by the BET method of 235 m ² / g.

Production Example 6 (Production of porous silica fine particles for comparison)
2.1 g of myristyltrimethylammonium chloride (C14 alkyltrimethylammonium salt) was dissolved in 40 g of 0.5 M hydrochloric acid and stirred at 25 ° C. To this, 4.3 g of tetraethoxysilane (TEOS) was added and stirred at pH 2.0 and 25 ° C. for 3 hours. Thereafter, 3.5 g of 25% ammonia solution was added and stirred at pH 9.0 and 25 ° C. for 1 hour. This stirred product was transferred to a tray and dried at 70 ° C. for 24 hours. The obtained solid was calcined at 580 ° C. for 10 hours to obtain 1.0 g of comparative porous silica fine particles (1 ′).

Production Example 7 (Preparation of composition for ink receiving layer)
Porous silica particles (1) 1.0 part, ion-exchanged water 51.5 parts, Charol DC-902P (dispersant, nitrogen-containing organic cationic polymer, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., 51.5% aqueous solution) 0 .78 parts, ZA-30 (Daiichi Rare Element Chemical Co., Ltd., zirconyl acetate) 0.48 parts, polyvinyl alcohol (water-soluble resin) solution 31.2 parts, 30% methionine sulfoxide (sulfur compound) 0.88 parts, 0.2 part of boric acid (crosslinking agent) and 1.5 part of Superflex 650 (nitrogen-containing organic cationic polymer emulsion, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) are mixed, and the ink receiving layer coating solution (1) was obtained. The composition of the polyvinyl alcohol (water-soluble resin) solution is as follows.

-PVA-235 ... 2.2 parts (saponification degree 88%, polymerization degree 3500, manufactured by Kuraray Co., Ltd.)
・ Ion-exchanged water ・ ・ ・ 28.2 parts ・ Diethylene glycol monobutyl ether ・ ・ ・ 0.7 parts (Butisenol 20P, Kyowa Hakko Chemical Co., Ltd.)
・ Emulgen 109P (surfactant, manufactured by Kao Corporation) 0.1 parts

Production Examples 8 to 11 (same as above)
Receptive layer coating liquids (2) to (5) were obtained in the same manner as in Production Example 7, except that the porous silica particles (2) to (5) were used instead of the porous silica particles (1).

Production Example 12 (Preparation of composition for comparative ink-receiving layer)
Except for using 0.9 parts of comparative porous silica particles (1 ') and 7.1 parts of vapor phase method silica fine particles (AEROSILL300SF75, manufactured by Nippon Aerosil Co., Ltd.) instead of porous silica particles (1). In the same manner as in Production Example 7, a comparative ink-receiving layer coating solution (1 ′) was obtained.

Example 1
On the corona-treated surface of the corona-treated PET film [manufactured by Unitika Ltd., emblet, film thickness 75 μm], the ink receiving layer coating solution (1) is applied with an extrusion die coater as follows. Was applied at 38 ° C. to form a coating layer. Specifically, the following in-line liquid was mixed in-line at a speed of 105.1 g / m 2 and at a speed of 3.3 g / m 2, and then coated on the support.

Composition of in-line liquid ・ Alphain 83 (manufactured by Daimei Chemical Co., Ltd.) 2.0 parts ・ Ion exchange water 7.8 parts ・ Himax SC-507 0.2 parts (dimethyl) Amine and epichlorohydrin polycondensate, manufactured by Hymo Co., Ltd.)

  Next, the coating layer formed by coating was dried with a hot air dryer at 80 ° C. (wind speed of 3 to 8 m / sec) until the solid content concentration of the coating layer became 24%. This coating layer showed constant rate drying during this period. Immediately after that, it was immersed in a basic solution having the following composition for 3 seconds to deposit 13 g / m 2 on the coating layer, and further dried at 72 ° C. for 10 minutes to form a single ink receiving layer on the support. .

<Composition of basic solution>
(1) Boric acid 1.3 parts (2) Ammonium carbonate (1st grade: manufactured by Kanto Chemical Co., Inc.) 5.0 parts (3) Zircozol AC-7 2.5 parts (Zirconyl ammonium carbonate, first rare element) (Chemical Industry Co., Ltd.)
(4) 85.2 parts of ion-exchanged water (5) 6.0 parts of polyoxyethylene lauryl ether (surfactant) (Emulgen 109P (10% aqueous solution), HLB value 13.6, manufactured by Kao Corporation)

  As described above, an inkjet recording medium (1) in which an ink receiving layer having a dry film thickness of 35 μm was provided on a support was produced. In addition, an ultra-thin section was prepared for this inkjet recording medium (1) with an ultramicrotome, and a transmission electron microscope (“JEM-2200FS” manufactured by JEOL Ltd.) was used. Observed at double. As a result, a layer in which the porous silica particles (E1) were arranged in a substantially single layer was formed with a thickness of about 100 nm on the surface opposite to the PET film (base material). An observation photograph when observed at 50,000 times is shown in FIG.

  The transparency of the obtained inkjet recording medium (1) and bleeding when printed by the inkjet method were evaluated by the following methods. The evaluation results are shown in Table 1.

<Transparency evaluation method>
The sample was visually observed under a three-wavelength fluorescent lamp and evaluated according to the following criteria.
○: The inkjet recording medium was clear and clear.
X: The inkjet recording medium had low transparency and was cloudy.

<Evaluation of bleeding>
Using a genuine ink set and an ink jet printer EP-801A (manufactured by Seiko Epson Corporation), magenta and black are adjacent to the ink receiving layer of the obtained ink jet recording medium under an environmental condition of 23 ° C. and 50% RH. A grid pattern (length of one side of grid: 0.28 mm) was printed in a 3 cm square area. Immediately thereafter, the ink jet recording medium was transferred to an environmental condition of 23 ° C. and 90% RH and left for 14 days. After 14 days, the film was sufficiently dried under the environmental conditions of 23 degrees and 50% RH, and then the degree of bleeding was visually evaluated and ranked according to the following evaluation criteria.

<Evaluation criteria>
A: No bleeding was observed.
B: Slight bleeding was observed, but there was no problem in practical use.
C: Bleeding was large and practically hindered.

Claims (11)

  In an ink jet recording medium having an ink-receiving layer containing porous silica particles on a support, the porous silica particles contain a mixed liquid (liquid A) containing tetraalkoxysilane, alkylamine and alcohol, ammonia, alcohol and water. In addition to a mixed liquid (liquid B) containing tetrahydrosilane and hydrolyzing and condensing the tetraalkoxysilane to obtain silica particles, and a method comprising removing alkylamine from the silica particles. An inkjet recording medium.   2. The ink jet recording medium according to claim 1, wherein the alkylamine is an amine compound having an alkyl group having 6 to 18 carbon atoms.   2. The ink jet recording medium according to claim 1, wherein the alcohol is one or more alcohols selected from the group consisting of methanol, ethanol and propanol.   The inkjet recording medium according to any one of claims 1 to 3, wherein the tetraalkoxysilane is at least one tetraalkoxysilane selected from the group consisting of tetramethoxysilane, tetraethoxysilane, and tetrapropoxysilane.   The process of obtaining the said silica particle is a process of adding the liquid mixture (A 'liquid) which further contains tetraalkoxysilane and alcohol, after adding the said A liquid to B liquid. Inkjet recording medium.   The inkjet recording medium according to claim 1, wherein the step of removing the alkylamine is a step of removing the silica particles by heating.   2. The ink jet recording medium according to claim 1, wherein the ratio [tetraalkoxysilane / alkylamine] of tetraalkoxysilane and alkylamine in the liquid A is in the range of 1 / 0.05 to 1/5 in terms of molar ratio.   The ink jet recording medium according to claim 1, wherein the content of tetraalkoxysilane in the liquid A is 10 to 60 parts by mass in 100 parts by mass of the A liquid.   2. The ink jet recording medium according to claim 1, wherein the amount of tetraalkoxysilane in the liquid A and the amount of water in the liquid B is 0.5 to 25 in a molar ratio [(water) / (tetraalkoxysilane)].   The inkjet recording medium according to claim 1, wherein the ink receiving layer contains a polyvinyl alcohol-based resin.   The inkjet recording medium according to claim 1, wherein the content of the porous silica particles is 0.1 to 1.0 part by mass with respect to 100 parts by mass of the water-soluble resin.