JP2010221509A - Method for manufacturing inkjet recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an inkjet recording material having a high glossy feeling, excellent in ink absorbing properties and color developing properties, and also excellent in water resistance and moisture-proof blotting properties with high productivity. <P>SOLUTION: The method for manufacturing the inkjet recording material is characterized in that a non-water absorbing substrate is coated with an undercoating layer coating liquid comprising a water-dispersible resin with a lowest film-forming temperature of ≥40°C, an alkali agent, and a boric acid or its derivative, and containing substantially no inorganic fine particle, and thereafter, a coating liquid for an ink receiving layer mainly comprising an inorganic fine particle with a mean secondary particle diameter of ≤500 nm and a polyvinyl alcohol or its derivative as a binder for the inorganic fine particle is applied thereon. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing an inkjet recording material, and produces an inkjet recording material having particularly high glossiness, excellent ink absorbability and color developability, and excellent water resistance and moisture bleeding resistance with high productivity. On how to do.

  As a recording material used in the ink jet recording method, a recording material in which an ink receiving layer is provided on a support such as paper or a plastic resin film is known. The ink receiving layer on the support is roughly classified into two types. One type is an ink receiving layer mainly composed of a water-soluble polymer, and the other type is a porous ink receiving layer mainly composed of an inorganic pigment and a resin binder.

  The former type of ink receiving layer absorbs ink by swelling the water-soluble polymer. The latter type of ink receiving layer absorbs ink in voids formed by inorganic pigments. Due to the difference in the mechanism for absorbing ink, the former type is called a swelling type (or polymer type), and the latter type is called a void type. In general, the former swelling type is excellent in gloss because the ink-receiving layer is a continuous and uniform film, but is inferior in ink absorption speed, that is, drying after printing. On the other hand, the latter gap type is characterized by excellent ink absorbability and high print density.

  In recent years, with the widespread use of digital cameras, gloss and image quality as high as photographic printing paper are required. When a water-absorbing support typified by paper is used as a support for an ink jet recording material used for such applications, there arises a problem called cockling in which the recording material is wavy or wrinkled when an image is printed. On the other hand, a recording material using a non-water-absorbing support such as polyolefin resin-coated paper or plastic resin film does not cause cockling. Therefore, a support for a recording material that requires high gloss and image quality equivalent to the above-mentioned photographic printing paper. Is preferably used. Since the water-absorbing support such as paper can give the support a certain amount of ink absorbability, the above-described swelling type ink receiving layer can also be used. On the other hand, the non-water-absorbing support is different from the water-absorbing support in that the support itself does not absorb ink, and therefore it is necessary to absorb ink only by the ink receiving layer. Therefore, a void-type ink receiving layer is suitably used for the non-water-absorbing support. When inorganic fine particles having an average secondary particle diameter of 500 nm or less are used as the inorganic pigment contained in the ink receiving layer, high ink absorption and printing can be achieved. In addition to density, a very high gloss recording material is obtained.

  Examples of inorganic fine particles having an average secondary particle diameter of 500 nm or less that are preferably used for the void-type ink-receiving layer include, for example, Japanese Patent No. 3321700, Japanese Patent No. 3371365, Japanese Patent No. 3798169 (Patent Document 1), and the like. Examples of the use of vapor phase silica are described in Japanese Patent No. 3411151, JP-A-10-181190, etc., and examples of use of pulverized sedimentation method silica are described in JP 2001-277712. JP-A-2002-225423 (Patent Document 2) discloses an example of using alumina or alumina hydrate.

  According to the method disclosed in the above-mentioned Patent Document 1 or the like, an ink jet recording material excellent in ink absorbability, glossiness, color developability, water resistance, moisture resistance and the like can be obtained. However, on the other hand, the ink receiving layer is coated with a coating solution in which vapor-phase-process silica, polyvinyl alcohol as its binder, and boric acid as a crosslinking agent for polyvinyl alcohol are contained in the same coating solution. The coating solution becomes extremely thick, especially at low temperatures. As a result, not only the handling as a coating solution becomes extremely difficult, but also the coating suitability is lowered, resulting in a coating defect, resulting in a decrease in productivity. . In order to make up for this drawback, the coating solution needs to be kept at a temperature slightly higher than room temperature, but it still has problems such as changes in liquid properties and generation of aggregates with the passage of time of the coating solution. .

  An ink receiving layer containing no inorganic fine particles, polyvinyl alcohol, or the like after the coating liquid containing boric acid or its derivative does not contain boric acid or its derivative in the coating liquid for the ink receiving layer and is coated on the support in advance and dried. A method of applying a coating liquid for use is described in JP 2007-38651 A, WO 2006/132286 pamphlet (Patent Documents 3 and 4), and the like. According to this method, an ink jet recording material excellent in gloss, image quality, and ink absorbability is obtained. In the production methods described in these methods, since the cross-linking agent previously applied on the support is not instantly diffused, the drying conditions after applying the ink-receiving layer coating liquid are set at the time rate instead of the drying rate in the production process. There is a need to. In other words, if drying is completed before the crosslinking reaction of the binder in the ink receiving layer has sufficiently progressed, the ink receiving layer will crack, but the time required for this crosslinking reaction is compared with the time required for drying. Then, the time required for the crosslinking reaction becomes longer, and the product is manufactured without fully utilizing the drying capacity of the equipment. As a result, there is a problem that productivity is lowered.

Japanese Patent No. 3798169 JP 2002-225423 A JP 2007-38651 A International Publication No. 2006/132286 Pamphlet

  An object of the present invention relates to a method for producing an ink jet recording material, and has a particularly high glossiness, excellent ink absorbability and color developability, and excellent water resistance and moisture bleeding resistance. It is to find a manufacturing method to manufacture.

  The above object of the present invention includes a water-dispersible resin having a minimum film-forming temperature of 40 ° C. or higher, an alkali agent, and boric acid or a derivative thereof on a non-water-absorbing support, and substantially contains inorganic fine particles. A coating solution for an undercoat layer, and then containing mainly inorganic fine particles having an average secondary particle diameter of 500 nm or less, and containing polyvinyl alcohol or a derivative thereof as a binder for the inorganic fine particles It was achieved by a method for producing an ink jet recording material, characterized by applying

  According to the present invention, it is possible to produce an inkjet recording material having high glossiness, excellent ink absorbability and color developability, and excellent water resistance and moisture bleeding resistance with high productivity.

  The inorganic fine particles having an average secondary particle diameter of 500 nm or less mainly contained in the ink receiving layer of the ink jet recording material of the present invention will be described. “Containing mainly inorganic fine particles” means that the inorganic fine particles are contained in an amount of 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 65% by mass with respect to the total solid content in the ink receiving layer. %, And the upper limit is about 95% by mass. The average secondary particle size referred to in the present invention can be obtained by measuring the diluted dispersion with a laser diffraction / scattering particle size distribution analyzer. Examples of the inorganic fine particles include various known inorganic fine particles such as synthetic amorphous silica, alumina, alumina hydrate, calcium carbonate, and magnesium carbonate. Synthetic amorphous silica, alumina, and alumina hydrate are preferably used. Synthetic amorphous silica is particularly preferably used. Synthetic amorphous silica includes a gas phase method, a wet method, and others. Vapor phase silica is also called a dry method and is generally made by flame hydrolysis. Specifically, a method of making silicon tetrachloride by burning with hydrogen and oxygen is generally known, but silanes such as methyltrichlorosilane and trichlorosilane can be used alone or in silicon tetrachloride instead of silicon tetrachloride. Can be used in a mixed state. Vapor phase silica is commercially available from Nippon Aerosil Co., Ltd. as Aerosil and Tokuyama Co., Ltd. as QS type.

The average particle diameter of the primary particles of vapor-phase process silica used in the ink receiving layer of the present invention is preferably 5 to 30 nm, more preferably 15 nm or less. More preferably, the primary particles have an average particle diameter of 5 to 15 nm and a specific surface area by the BET method of 200 m ² / g or more. The BET method referred to in the present invention is one of powder surface area measurement methods by vapor phase adsorption, and is a method for determining the total surface area, that is, the specific surface area of a 1 g sample from the adsorption isotherm. Usually, nitrogen gas is often used as the adsorbed gas, and the most frequently used method is to measure the amount of adsorption from the change in pressure or volume of the gas to be adsorbed. The most prominent expression for expressing the isotherm of multimolecular adsorption is the Brunauer, Emmett, and Teller formula, called the BET formula, which is widely used for determining the surface area. The adsorption amount is obtained based on the BET formula, and the surface area is obtained by multiplying the area occupied by one adsorbed molecule on the surface. In addition, the average primary particle diameter described here is obtained as the particle diameter by the diameter of a circle equal to the projected area of each of 100 particles existing within a certain area by electron microscope observation of dispersed particles.

  Wet process silica is further classified into precipitation process silica and gel process silica according to the production method. Precipitated silica is produced by reacting sodium silicate and sulfuric acid under alkaline conditions, and the silica particles that have grown are agglomerated and settled, and are then commercialized through filtration, water washing, drying, pulverization and classification. The silica secondary particles produced by this method become gently agglomerated particles, and particles that are relatively easy to grind are obtained. Precipitated silica is commercially available, for example, as a nip seal from Tosoh Silica Co., Ltd., as a Toku Seal from Tokuyama Co., Ltd., and as a fine seal. Gel silica produces silicate sol by reacting sodium silicate and sulfuric acid under acidic conditions. The silicate sol gradually polymerizes to form primary particles, and further, a three-dimensional aggregate is formed and gelled. This silica is pulverized and pulverized by a general method such as airflow pulverization. That is, in the gel method, the reaction polymerization is carried out on the acidic side, the mixture is allowed to stand until it forms a gel, washed with water and dried to obtain a gel method silica. For example, it is commercially available as nip gel from Tosoh Silica Co., Ltd. and as Mizukasil from Mizusawa Chemical Co., Ltd. Although colloidal silica belongs to wet-process silica, it is not suitable for inorganic fine particles mainly contained in the ink receiving layer of the present invention because it has a cohesive structure in the coating layer and its ink absorption ability is extremely low.

  The average secondary particle size of the inorganic fine particles used in the ink receiving layer of the present invention is 500 nm or less, and the vapor phase silica and the wet method silica are average secondary particle sizes of the silica in the presence of a cationic compound. Can be used that is pulverized and dispersed to 500 nm or less, preferably 10 to 300 nm, more preferably 20 to 200 nm. As the pulverization and dispersion method, gas phase method silica or wet method silica and a dispersion medium are premixed by ordinary propeller stirring, turbine type stirring, homomixer type stirring, etc., and then a media mill such as a ball mill, a bead mill, a sand grinder, It is preferable to perform dispersion using a pressure disperser such as a high-pressure homogenizer or an ultra-high pressure homogenizer, an ultrasonic disperser, a thin film swirl disperser, or the like.

  A cationic polymer or a water-soluble metal compound can be used as the cationic compound used for dispersion of the gas phase method silica and the wet method silica. As the cationic polymer, polyethyleneimine, polydiallylamine, polyallylamine, alkylamine polymer, JP-A 59-20696, JP-A 59-33176, JP-A 59-33177, JP 59-1555088, JP 60-83882, JP 62-198493, JP 1-40371, JP 6-234268, JP 7-125411, JP No. 10-1937776, Japanese Patent No. 1606817, Japanese Patent No. 1609157, Japanese Patent No. 1840377, Japanese Patent No. 19991771, Japanese Patent No. 201111849, Japanese Patent No. 2667162, etc. Polymers having amino groups and quaternary ammonium bases are preferably usedIn particular, diallylamine derivatives are preferably used as the cationic polymer. In terms of dispersibility and dispersion viscosity, the molecular weight of these cationic polymers is preferably about 2,000 to 100,000, and particularly preferably about 2,000 to 30,000.

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

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

  As the alumina used in the present invention, γ-alumina which is a γ-type crystal of aluminum oxide is preferable, and among them, a δ group crystal is preferable. γ-alumina can make primary particles as small as about 10 nm. Usually, secondary particles of thousands to tens of thousands of nanometers are averaged by ultrasonic, high-pressure homogenizer, counter collision type jet crusher, etc. What grind | pulverized the particle diameter to 500 nm or less, Preferably about 20-300 nm can be used.

Alumina hydrate of the present invention is represented by the structure formula of _{Al 2 O 3 · nH 2 O} (n = 1~3). The alumina hydrate can be obtained by a known production method such as hydrolysis of aluminum alkoxide such as aluminum isopropoxide, neutralization of aluminum salt with alkali, hydrolysis of aluminate and the like. The average secondary particle diameter of the alumina hydrate used in the present invention is 500 nm or less, preferably 20 to 300 nm.

  The above-mentioned alumina and alumina hydrate used in the present invention are used in the form of a dispersion dispersed by a known dispersant such as acetic acid, lactic acid, formic acid, nitric acid and the like.

In the present invention, the coating amount of inorganic fine particles contained mainly in the ink receiving layer is preferably in the range of 8~40g / ^{m 2} from the viewpoint of ink absorbency, the range of 10~35g / ^{m 2} is more preferable. Ink jet recording materials containing such a large number of inorganic fine particles are difficult to produce with high productivity, but the present invention is particularly effective in this mode.

  The ink receiving layer of the present invention has a binder in order to maintain the properties as a film. As this binder, a hydrophilic binder that is highly transparent and can obtain higher ink permeability is preferable. When the hydrophilic binder is used, the hydrophilic binder swells at the initial penetration of the ink and blocks the voids. From this point of view, it is important that a hydrophilic binder having a relatively low swelling property is used. From the above, polyvinyl alcohol or a derivative thereof is used as a hydrophilic binder.

  Particularly preferred among the polyvinyl alcohols in the ink-receiving layer of the present invention are those having a saponification degree of 80% or more or those having been completely saponified. Polyvinyl alcohol having an average degree of polymerization of 500 to 5,000 is preferred.

  Examples of the polyvinyl alcohol derivative that can be used in the ink receiving layer of the present invention include modified polyvinyl alcohols such as cation modification, silanol modification, anion modification, acetoacetyl modification, and diacetone acrylamide modification. As the cation-modified polyvinyl alcohol, for example, polyvinyl alcohol having a primary to tertiary amino group or a quaternary ammonium group in the main chain or side chain of polyvinyl alcohol as described in Japanese Patent No. 2039166 is suitably used. It is done.

  In the ink receiving layer of the present invention, other binders can be used in combination. In that case, the amount is preferably 40% by mass or less with respect to polyvinyl alcohol. The total amount of these binders contained in the ink receiving layer of the present invention is preferably 1 to 50% by mass with respect to the mass of the inorganic fine particles mainly contained in the ink receiving layer. More preferably, it is 3-40% mass, More preferably, it is 5-35% mass.

  The ink-receiving layer coating liquid of the present invention preferably contains substantially no boric acid or its derivative, but can be contained in trace amounts. The allowable content is preferably 20% by mass or less, more preferably 10% by mass or less, based on boric acid or its derivative used in the undercoat layer of the present invention.

  In the present invention, for the purpose of improving water resistance and ink absorbability, the ink receiving layer can be hardened with a suitable hardener other than boric acid or its derivatives. Specific examples of the hardener include aldehyde compounds such as formaldehyde and glutaraldehyde, ketone compounds such as diacetyl and chloropentanedione, bis (2-chloroethylurea), 2-hydroxy-4,6-dichloro-1 , 3,5-triazine, a compound having a reactive halogen as described in US Pat. No. 3,288,775, divinyl sulfone, a compound having a reactive olefin as described in US Pat. No. 3,635,718, N-methylol compounds as described in US Pat. No. 2,732,316, isocyanates as described in US Pat. No. 3,103,437, US Pat. No. 3,017,280, US Pat. No. 2,983 Aziridine compounds as described in US Pat. No. 611, carbodiimide compounds as described in US Pat. No. 3,100,704 , Epoxy compounds as described in U.S. Pat. No. 3,091,537, halogen carboxaldehydes such as mucochloric acid, dioxane derivatives such as dihydroxydioxane, chromium alum, zirconium sulfate and the like, one or more of these They can be used in combination. The addition amount of the hardener other than boric acid or its derivative is about 0.1 to 25% by mass, preferably 0.2 to 15%, based on the total amount of boric acid or its derivative contained in the undercoat layer and the ink receiving layer. % By mass.

  In the present invention, the timing of applying the ink receiving layer coating liquid may be any stage after the application of the undercoat layer coating liquid described later, but from the viewpoint of further reducing defects during coating, the undercoat layer coating liquid is used. It is preferable after coating and drying.

  The undercoat layer of the present invention requires a binder from the viewpoint of the uniformity of the undercoat layer. When the binder is not contained, a granular solid such as boric acid is formed on the support, which is not preferable because glossiness is lowered. From the viewpoint of the temporal stability of the coating solution for the undercoat layer, it is important that such a binder does not cause a crosslinking reaction with boric acid or a derivative thereof. Since it is necessary to instantaneously supply the cross-linking agent to the ink receiving layer, it is important that the binder for the undercoat layer does not form a continuous film during drying. When a binder that forms a continuous coating is selected as the binder, it takes time for the crosslinking agent to elute and diffuse from the coating, resulting in the diffusion rate and diffusion of the crosslinking agent into the ink receiving layer. Since the amount becomes insufficient, it is not preferable. For this reason, a water-dispersible resin having a minimum film forming temperature of 40 ° C. or higher is selected as the binder for the undercoat layer. When a water-dispersible resin having a minimum film forming temperature lower than 40 ° C. is used as the binder for the undercoat layer, a continuous film is formed when the undercoat layer coating solution is applied and dried, and then the ink receiving layer coating solution is used. When applied, the crosslinking agent contained in the undercoat layer does not sufficiently diffuse into the ink receiving layer. Therefore, it is necessary to apply a crosslinking agent more than the necessary amount to the undercoat layer. Increasing the wet coating amount of the undercoat layer is not preferable because it causes a decrease in productivity.

  Various water-dispersible resins having a minimum film-forming temperature of 40 ° C. or higher used in the present invention can be used. For example, a polyurethane emulsion or an emulsion obtained by polymerizing a vinyl monomer.

  Examples of suitable vinyl monomers include acrylic acid and ester compounds thereof (methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, t-butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate). Etc.), α-substituted acrylic acid and its ester compounds (methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, etc.), acrylamide and its substitutes (butyl acrylamide, hexyl acrylamide) Etc.), vinyl esters (eg vinyl acetate), vinyl halides (eg vinyl chloride), vinylidene halides (eg vinylidene chloride), vinyl ethers (vinyl methyl ether, vinyl octylate) Etc.), styrene, divinylbenzene, ethylene, butadiene, acrylonitrile. Depending on the required function, a copolymer or a core-shell type water-dispersible resin may be used, or at least two or more water-dispersible resins may be used in combination.

  The minimum film-forming temperature of the water-dispersible resin needs to be 40 ° C. or higher because of the drying temperature of the dryer. When drying at a lower temperature, a water-dispersible resin having a lower minimum film-forming temperature can be used, but the production efficiency is lowered. The minimum film forming temperature is preferably 50 ° C. or higher, and more preferably 60 ° C. or higher. The upper limit is preferably 300 ° C. The particle size of the water-dispersible resin is not particularly limited, but is preferably 500 nm or less in order to provide a recording material having a high gloss feeling.

  In the undercoat layer of the present invention, in addition to the water-dispersible resin, a known resin binder may be used in combination as long as the diffusion of the crosslinking agent to the ink receiving layer is not hindered. For example, cellulose derivatives such as carboxymethyl cellulose and hydroxypropyl cellulose, starch and various modified starches, gelatin and various modified gelatins, chitosan, carrageenan, casein, soy protein, polyvinyl alcohol, various modified polyvinyl alcohols, polyvinylpyrrolidone, polyacrylamide, etc. are required It can be used together depending on the situation. The amount of the resin binder added is preferably 20% by mass or less, more preferably 15% by mass or less, more preferably 5% by mass or less, based on the solid content of the water-dispersible resin.

The boric acid or derivative thereof contained in the undercoat layer of the present invention means an acid having a composition of xB ₂ O ₃ .yH ₂ O (where x and y are integers on the left), specifically, orthoboric acid. , Metaboric acid, diboric acid, tetraboric acid, pentaboric acid, octaboric acid and the like. Of these, orthoboric acid is preferably used. A preferable addition amount of boric acid or a derivative thereof used in the present invention is 1 to 35% by mass with respect to a mass of polyvinyl alcohol or a derivative thereof contained in the ink receiving layer.

  The undercoat layer of the present invention contains an alkaline agent. The solubility of boric acid or its derivatives in water is relatively low. For example, orthoboric acid is about 4% by mass at 20 ° C. In order to apply the required addition amount, the wet coating amount of the coating solution for the undercoat layer is Inevitably increases. However, when boric acid or a derivative thereof dissolved in the presence of an alkaline agent is added in order to incorporate boric acid or a derivative thereof in the coating solution for the undercoat layer of the present invention, an aqueous solution of boric acid or a derivative thereof having a high concentration at room temperature can be obtained. As such an alkali agent, sodium hydroxide, potassium hydroxide, borax and the like are preferably used, and among them, borax which can supply more borate ions is more preferably used. The preferable addition amount of the alkaline agent in the coating solution for the undercoat layer used in the present invention is 8% by mass or more, more preferably 10 to 400% by mass with respect to the mass of boric acid or its derivative in the undercoat layer. is there.

  The undercoat layer coating solution of the present invention contains substantially no inorganic fine particles. When inorganic fine particles are contained, the viscosity of the coating solution increases, and the coating property of the coating solution for the undercoat layer is improved. However, it is not preferable that the coating liquid for undercoat layer of the present invention contains inorganic fine particles having an average secondary particle diameter exceeding 500 nm, for example, because gloss reduction due to the particle diameter of the inorganic fine particles occurs.

  On the other hand, when inorganic fine particles having an average secondary particle diameter of 500 nm or less are used in the undercoat layer coating solution of the present invention, there is no concern about gloss reduction, but an appropriate binder must be used. As a binder for such finely dispersed inorganic fine particles, polyvinyl alcohol or a derivative thereof is preferable, but it is not preferable for the undercoat layer coating liquid of the present invention because it causes a crosslinking reaction with boric acid or a derivative thereof. In binders other than polyvinyl alcohol or its derivatives, a very large addition amount is required to suppress cracking. As a result, the diffusion rate of the cross-linking agent boric acid or its derivative may be decreased, or the coating amount of the coating solution for the undercoat layer may be increased, resulting in a decrease in the uniformity of the undercoat layer. Absent. For the above reasons, the undercoat layer coating solution of the present invention contains substantially no inorganic fine particles. Here, “substantially” means 15% by mass or less based on the dry coating amount of the undercoat layer, preferably 10% by mass or less, and more preferably 5% by mass or less.

  In the present invention, it is preferable to use an acid in order to adjust the film surface pH of the ink receiving layer of the ink jet recording material. Various acids can be used as the acid, and an acidic zirconium compound having both the fixing property of the ink and the action of crosslinking the binder is preferably used. Examples of the acidic zirconium compound include hydroxy zirconium chloride, zirconium oxychloride, zirconium nitrate, and zirconium acetate. In addition, a weak acid is also preferably used from the viewpoint of easy adjustment of the film surface pH. Examples of weak acids include lactic acid, acetic acid, succinic acid, citric acid, malic acid, ascorbic acid and the like.

  In the present invention, the ink-receiving layer and the undercoat layer may further contain a cationic compound for the purpose of improving color developability. Examples of the cationic compound include the cationic polymer and the water-soluble metal compound mentioned in the description of the dispersion of silica. Examples of water-soluble metal compounds include water-soluble salts of metals selected from calcium, barium, manganese, copper, cobalt, nickel, iron, zinc, chromium, magnesium, tungsten, and molybdenum. Specifically, for example, calcium acetate, calcium chloride, calcium formate, calcium sulfate, barium acetate, barium sulfate, barium phosphate, manganese chloride, manganese acetate, manganese formate dihydrate, manganese ammonium sulfate hexahydrate, chloride Cupric, ammonium copper (II) chloride dihydrate, copper sulfate, cobalt chloride, cobalt thiocyanate, cobalt sulfate, nickel sulfate hexahydrate, nickel chloride hexahydrate, nickel acetate tetrahydrate, sulfuric acid Nickel ammonium hexahydrate, nickel amidosulfate tetrahydrate, ferrous bromide, ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, zinc bromide, zinc chloride, zinc nitrate Hexahydrate, zinc sulfate, zinc p-phenolsulfonate, chromium acetate, chromium sulfate, magnesium sulfate, magnesium chloride hexahydrate, magnesium citrate Nonahydrate, sodium phosphotungstate, sodium tungsten citrate, 12 tungstophosphoric acid n hydrate, 12 tungstosilicic acid 26 hydrate, molybdenum chloride, 12 molybdophosphoric acid n hydrate, etc. A preferable cationic compound is a compound composed of a cationic polymer having a molecular weight of about 5,000 to 100,000 and aluminum or a Group 4A metal (for example, zirconium or titanium) in the periodic table, and particularly preferably contains an aluminum compound. These cationic compounds may be used alone or in combination with a plurality of compounds.

  In the present invention, the ink receiving layer and the undercoat layer further include a surfactant, a coloring dye, a coloring pigment, an ink coloring agent fixing agent, an ultraviolet absorber, an antioxidant, a pigment dispersant, an antifoaming agent, a leveling agent, Various known additives such as preservatives, fluorescent brighteners and viscosity stabilizers can also be added.

  Non-water-absorbing supports used in the present invention are polyester resins such as polyethylene terephthalate and polyethylene naphthalate, diacetate resins, triacetate resins, nitrocellulose, cellulose ester resins such as cellulose acetate, polyolefin resins, acrylic resins, and polycarbonate resins. Non-water-absorbing supports such as plastic resin films such as polyvinyl chloride, polyimide resin, polysulfone, polyphenylene oxide, cellophane and celluloid, and polyolefin resin-coated paper are used. Among non-water-absorbing supports, polyolefin resin-coated paper in which at least one surface of the base paper is coated with a polyolefin resin is preferably used. As the pulp constituting the base paper, natural pulp, recycled pulp, synthetic pulp or the like is used alone or in combination of two or more. This base paper may be blended with additives such as sizing agent, paper strength enhancing agent, filler, antistatic agent, fluorescent brightening agent, dye and the like generally used in papermaking. Alternatively, a surface sizing agent, a surface paper strength agent, a fluorescent brightening agent, an antistatic agent, a dye, an anchor agent, or the like may be applied on the surface.

Further, the thickness of the base paper is not particularly limited, but preferably has a good surface smoothness such as a paper that is compressed during or after paper making by applying pressure with a calendar or the like, and its basis weight is 30 to 250 g / m ² is preferred. However, the density of the base paper is 1.10 g / cm ³ or less, preferably 0.6 to 1.05 g / cm ³ for rigidity. If the density is too small, it is difficult to obtain uniform surface smoothness even if resin coating is performed.

  The polyolefin resin is a copolymer composed of two or more olefins such as low density polyethylene, high density polyethylene, polypropylene, polybutene, polypentene and the like, or an ethylene-propylene copolymer, and a mixture thereof. Those having various densities and melt viscosity indices (melt index) can be used alone or in combination.

  In polyolefin resins, white pigments such as titanium oxide, zinc oxide, talc, calcium carbonate, fatty acid amides such as stearic acid amide and arachidic acid amide, zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, etc. Fatty acid metal salts, antioxidants such as hindered phenol derivatives, blue pigments and dyes such as cobalt blue, ultramarine blue, cecilian blue, phthalocyanine blue, magenta pigments and dyes such as cobalt violet, fast violet, manganese purple, fluorescent It is preferable to add various additives such as brighteners and ultraviolet absorbers in appropriate combinations.

  The polyolefin resin-coated paper used in the present invention is produced by a so-called extrusion coating method in which a heated and melted resin is cast on a traveling base paper, and the surface or both sides thereof are coated with the resin. Moreover, it is preferable to subject the base paper to an activation treatment such as corona discharge treatment or flame treatment before coating the resin on the base paper. The surface (front surface) of the polyolefin resin-coated paper on which the ink receiving layer is applied is processed into a glossy surface, a matte surface, or the like according to the application. It is not necessary to coat the back surface with a resin, but it is preferable to coat the resin from the viewpoint of curling prevention. The back surface is usually a matte surface, and an active treatment such as corona discharge treatment or flame treatment can be applied to the front surface or both the front and back surfaces as required. Further, the thickness of the polyolefin resin-coated paper is not particularly limited, but is generally coated on the surface or both sides of the surface to a thickness of 5 to 50 μm on one side.

  In the present invention, the coating method of the coating solution for the undercoat layer and the ink receiving layer is not particularly limited, and a known coating method can be used. Examples include an air knife method, a doctor blade method, a wire rod method, a slide bead method, a curtain method, an extrusion method, a gravure method, a roll coating method, and a slot coater method.

  When the undercoat layer coating solution of the present invention is applied on a non-water-absorbing support, corona discharge treatment, flame treatment, ultraviolet irradiation treatment, plasma treatment, or the like may be performed prior to coating.

  In the present invention, it is preferable to provide an undercoat layer mainly composed of a natural polymer compound or a synthetic resin on the surface of the non-water-absorbing support on which the ink receiving layer and the undercoat layer are provided in order to improve the coating property. The undercoat layer provided on the non-water-absorbing support is mainly composed of natural polymer compounds such as gelatin and casein and synthetic resins. Examples of such synthetic resins include acrylic resins, polyester resins, vinylidene chloride, vinyl chloride resins, vinyl acetate resins, polystyrene, polyamide resins, polyurethane resins, and the like.

  The undercoat layer is provided on the non-water-absorbing support with a film thickness (dry film thickness) of 0.01 to 5 μm. Preferably it is the range of 0.05-5 micrometers.

  Various back coat layers can be coated on the non-water-absorbent support in the present invention for antistatic properties, transportability, curl adjustment and the like. The backcoat layer can contain an inorganic antistatic agent, an organic antistatic agent, a resin binder, latex, a pigment, a curing agent, a surfactant, and the like in appropriate combination.

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

<Preparation of polyolefin resin-coated paper support>
A 1: 1 mixture of hardwood bleached kraft pulp (LBKP) and softwood bleached sulfite pulp (NBSP) was beaten to 300 ml with Canadian Standard Freeness to prepare a pulp slurry. As a sizing agent, alkylketene dimer is 0.5% to pulp, polyacrylamide is 1.0% to pulp, and cationized starch is 2.0% to pulp. Polyamide epichlorohydrin resin is 0 to pulp. 0.5% added and diluted with water to give a 0.2% slurry. This slurry was made with a long paper machine to a basis weight of 170 g / m ² , dried and conditioned to obtain a polyolefin resin-coated paper base paper. A polyethylene resin composition in which 10 parts of anatase-type titanium is uniformly dispersed is melted at 320 ° C. with respect to 100 parts of low-density polyethylene having a density of 0.918 g / cm ³ on a base paper made at a temperature of 200 m / min. Extrusion coating was carried out to a thickness of 35 μm, and a finely roughened cooling roll was used for extrusion coating to obtain a front surface. Melted at similarly 320 ° C. The blend resin composition of the low density polyethylene resin 30 parts of a density 0.962 g / cm 70 parts high density polyethylene resin of ³ and a density 0.918 g / cm ³ on the other surface, the thickness Extrusion-coating to a thickness of 30 μm, and extrusion coating using a cooling roll having a roughened surface was used as the back surface.

The polyolefin resin-coated paper surface was subjected to high-frequency corona discharge treatment, and then an undercoat layer having the following composition was coated and dried so that the gelatin content was 50 mg / m ² (about 0.05 μm) to prepare a support.

<Underlayer>
Lime-processed gelatin 100 parts Sulfosuccinic acid-2-ethylhexyl ester salt 2 parts Chrome alum 10 parts

<Preparation of gas phase method silica dispersion 1>
Dimethylallylammonium chloride homopolymer (molecular weight 9,000, 3 parts) and gas phase method silica (average primary particle diameter 7 nm, 100 parts) are added to water, and a sawtooth blade type disperser (blade peripheral speed 20 m / second). And passed through a pressure homogenizer twice under the condition of 40 MPa to obtain a gas phase method silica dispersion 1 having a solid content concentration of 20%. It was 140 nm as a result of measuring the dispersed particle diameter of this gas phase method silica dispersion with the particle size distribution analyzer (Horiba Ltd. make, LA-920).

<Preparation of coating liquid 1 for ink receiving layer>
An ink receiving layer coating solution 1 was prepared using the vapor phase silica dispersion 1. The solid content concentration of the coating solution at this time was 16.2%.
<Ink-receiving layer coating solution 1>
Gas phase method silica dispersion 1 103 parts polyvinyl alcohol 21 parts (manufactured by Kuraray Co., Ltd., PVA235)
0.05 part of betaine surfactant (Swanol AM-2150 manufactured by Nippon Surfactant Co., Ltd.)
Ethanol was added so that it might become 5 mass% with respect to the said coating liquid.

<Preparation of additive liquid 1 for ink receiving layer>
The following additives were dissolved in water to prepare an ink receiving layer additive solution 1. The non-volatile content concentration of the additive solution at this time was 10.8%. In addition, the following number of parts is the number of parts with respect to 100 parts of vapor phase method silica in the ink receiving layer coating liquid 1.
<Additive liquid 1 for ink receiving layer>
2 parts of basic polyaluminum hydroxide (Purechem WT, manufactured by Riken Green Co., Ltd.)
3,8-dithiaoctanediol 2 parts Lactic acid 2.3 parts

<Preparation of undercoat layer coating solution 1>
The following additives were dissolved or dispersed in water to prepare an undercoat layer coating solution 1.
<Coating liquid 1 for undercoat layer>
1000g of water
Orthoboric acid 66.7g
Borax 66.7g
Superflex 130 1400g
(Urethane water dispersion, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., minimum film-forming temperature 55 ° C., solid content concentration 35%)
Solid content concentration 24.6%

<Preparation of recording material 1>
On the support thus obtained, the undercoat layer coating solution 1 was applied by a rod bar method so that the solid content coating amount was 3.94 g / m ^2, and dried at 50 ° C. In calculation, the amount of boric acid applied at this time was 0.42 g / m ² .

Subsequently, it was applied on the undercoat layer obtained as described above using an extrusion-type bar so that the solid content of the ink-receiving layer coating solution 1 was 24 g / m ² . Immediately before applying the ink-receiving layer coating liquid 1, the ink-receiving layer additive liquid 1 was mixed with the ink-receiving layer coating liquid 1, stirred, and then applied to obtain a recording material 1. At the time of drying, a metal roll cooled to 0 ° C. was pressed against the opposite side of the support on the coated surface for 20 to 30 seconds, and then dried with a dryer set at 42 ° C. At the time of drying, the time required from when the coated material entered the dryer until the drying was completed was measured. The recording material 1 took 90 seconds to dry.

<Preparation of recording material 2>
A recording material 2 was obtained in the same manner as the recording material 1 except that the undercoat layer coating solution 1 was changed to the following undercoat layer coating solution 2 in the production of the recording material 1. The time required for drying the recording material 2 was 90 seconds.

<Coating liquid 2 for undercoat layer>
1000g of water
Orthoboric acid 133.4g
Sodium hydroxide 18.3g
Superflex 130 1400g
Solid content 25.1%

<Preparation of recording material 3>
A recording material 3 was obtained in the same manner as the recording material 1 except that the undercoat layer coating solution 1 was changed to the undercoat layer coating solution 3 described below in the production of the recording material 1. The time required for drying the recording material 3 was 90 seconds.

<Undercoat layer coating solution 3>
1000g of water
Orthoboric acid 66.7g
Borax 66.7g
Superflex 870 1633g
(Urethane aqueous dispersion, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., minimum film-forming temperature 70 ° C., solid content concentration 30%)
Solid concentration 22.5%

<Preparation of recording material 4>
A recording material 4 was obtained in the same manner as the recording material 1 except that the undercoat layer coating solution 1 was changed to the undercoat layer coating solution 4 in the production of the recording material 1 described above. The time required for drying the recording material 4 was 90 seconds.

<Undercoat layer coating solution 4>
1000g of water
Orthoboric acid 80.4g
Borax 53.4g
Superflex 130 1400g
Solid content concentration 24.6%

<Preparation of recording material 5>
A recording material 5 was obtained in the same manner as the recording material 1 except that the undercoat layer coating solution 1 was changed to the following undercoat layer coating solution 5 in the production of the recording material 1. The time required for drying the recording material 5 was 90 seconds.

<Coating liquid 5 for undercoat layer>
1000g of water
Orthoboric acid 53.4g
Borax 80.4g
Superflex 130 1400g
Solid content concentration 24.6%

<Preparation of recording material 6>
A recording material 6 was obtained in the same manner as the recording material 1 except that 2.3 parts of lactic acid in the ink receiving layer additive liquid 1 was changed to 1.7 parts of acetic acid in the production of the recording material 1. The time required for drying the recording material 6 was 90 seconds.

<Preparation of recording material 7>
A recording material 7 was obtained in the same manner as the recording material 1 except that 2.3 parts of lactic acid in the ink-receiving layer additive solution 1 was changed to 1.4 parts of citric acid in the production of the recording material 1. The time required for drying the recording material 7 was 90 seconds.

<Preparation of recording material 8>
In the production of the recording material 1, the same as the recording material 1 except that 2.3 parts of lactic acid in the additive liquid 1 for ink receiving layer was changed to 0.5 part of hydroxy zirconium chloride (ZC-2 manufactured by Nippon Light Metal Co., Ltd.). Thus, a recording material 8 was obtained. The time required for drying the recording material 8 was 90 seconds.

<Preparation of recording material 9>
In the production of the recording material 1, the undercoat layer coating solution 1 was changed to the following undercoat layer coating solution 9 and applied so that the solid content coating amount of the undercoat layer coating solution 9 was 0.84 g / m ² . A recording material 9 was obtained in the same manner as the recording material 1 except for the above. The time required for drying the recording material 9 was 90 seconds.

<Coating liquid 9 for undercoat layer>
1000g of water
Orthoboric acid 66.7g
Borax 66.7g
Solid content 11.8%

<Preparation of recording material 10>
A recording material 10 was obtained in the same manner as the recording material 1 except that the undercoat layer coating solution 1 was changed to the following undercoat layer coating solution 10 in the production of the recording material 1. The time required for drying the recording material 10 was 120 seconds.
<Coating liquid 10 for undercoat layer>
1000g of water
Orthoboric acid 66.7g
Borax 66.7g
Superflex 700 1400g
(Urethane aqueous dispersion, manufactured by Daiichi Kogyo Kagaku Co., Ltd., minimum film forming temperature of 5 ° C. or lower, solid content concentration of 35%)
Solid content concentration 24.6%

<Preparation of recording material 11>
A recording material 11 was obtained in the same manner as the recording material 1 except that the undercoat layer coating solution 1 was changed to the following undercoat layer coating solution 11 in the production of the recording material 1. The time required for drying the recording material 11 was 90 seconds.
<Coating liquid 11 for undercoat layer>
1000g of water
Orthoboric acid 66.7g
Borax 66.7g
Superflex 860 1225g
(Urethane aqueous dispersion, manufactured by Daiichi Kogyo Kagaku Co., Ltd., minimum film-forming temperature 28 ° C., solid content concentration 40%)
Solid content concentration 26.4%

<Preparation of recording material 12>
On the support obtained in the preparation of the recording material 1, the following undercoat layer coating solution 12 is applied by a rod bar method so that the solid content coating amount is 7.01 g / m ² and dried at 50 ° C. did. In calculation, the amount of boric acid applied at this time was 0.84 g / m ² .
<Coating liquid 12 for undercoat layer>
3400g of water
Orthoboric acid 133.4g
Superflex 130 1400g
Solid content 12.6%

Next, a recording material 12 was obtained in the same manner as the recording material 1 except that the ink receiving layer additive solution 1 was changed to the following ink receiving layer additive solution 12 on the obtained undercoat layer. The time required for drying the recording material 12 was 90 seconds.
<Ink-Receptive Layer Additive Liquid 12>
2 parts of basic polyaluminum hydroxide (Purechem WT, manufactured by Riken Green Co., Ltd.)
Sodium acetate 1.2 parts 3,8-dithiaoctanediol 2 parts solids concentration 11.0%

<Preparation of recording material 13>
On the support obtained in the production of the recording material 1, coating was performed using an extrusion-type bar so that the solid content coating amount of the following coating liquid 13 for ink receiving layer was 24 g / m ² . Immediately before applying the ink receiving layer coating solution 13, the ink receiving layer additive solution 12 was mixed with the ink receiving layer coating solution 13, and then applied to obtain a recording material 13. The conditions after the application were the same as in the production of the recording material 1. The time required for drying the recording material 13 was 160 seconds.
<Ink-receiving layer coating solution 13>
Gas phase silica dispersion 1 103 parts Orthoboric acid 4 parts Polyvinyl alcohol 23 parts (Kuraray Co., Ltd. PVA235)
0.05 part of betaine surfactant (Swanol AM-2150 manufactured by Nippon Surfactant Co., Ltd.)
Solid content concentration of 12.2% with ethanol added to 5% by mass with respect to the coating solution

<Preparation of recording material 14>
A recording material 14 was obtained in the same manner as the recording material 1 except that the undercoat layer coating solution 1 was changed to the following undercoat layer coating solution 14 in the production of the recording material 1. The time required for drying the ink receiving layer of the recording material 14 was 140 seconds.

<Undercoat layer coating solution 14>
3000g of water
490g lime processed gelatin
Orthoboric acid 66.7g
Borax 66.7g
Solid content 17.2%

<Preparation of recording material 15>
In the production of the recording material 1, the vapor phase silica having a solid content concentration of 20% was prepared in the same manner as the recording material 1 except that the dimethylallyl ammonium chloride homopolymer was not added during the production of the vapor phase silica dispersion 1. Dispersion 2 was obtained. The gas phase method silica dispersion 2 obtained had an average secondary particle size of 160 nm. The following undercoat layer coating solution 15 was obtained using the gas phase method silica dispersion 2. The solid content concentration of the vapor phase method silica in the undercoat layer coating solution 15 was 20.4%. The recording material 15 was obtained in the same manner as the recording material 1 except that the undercoat layer coating solution 1 in the recording material 1 was changed to the undercoat layer coating solution 15 and the solid content coating amount was changed to 9.1 g / m ^2. It was. The time required for drying the recording material 15 was 90 seconds.

<Coating liquid 15 for undercoat layer>
1300g of water
Orthoboric acid 66.7g
Borax 66.7g
Superflex 130 1400g
Gas phase method silica dispersion 2 800g
Solid content concentration 21.6%

<Preparation of wet silica dispersion 1>
Dimethylallylammonium chloride homopolymer (molecular weight 9,000, 7 parts) and nip gel AZ-200 (average secondary particle size 1.9 μm, 100 parts) are added to water, and a sawtooth blade type disperser (blade peripheral speed) 20 m / sec) to obtain a wet silica dispersion 1 having a solid concentration of 20%. It was 1.9 micrometers as a result of measuring the dispersed particle diameter of this wet silica dispersion liquid 1 with the particle size distribution analyzer (the Horiba make, LA-920).

<Preparation of recording material 16>
A recording material 16 was prepared in the same manner as the recording material 15 except that the vapor phase silica dispersion 2 was changed to the wet silica dispersion 1 in the preparation of the recording material 15. The time required for drying the recording material 16 was 90 seconds.

Each information recording medium obtained as described above was evaluated as follows. The results are shown in Table 1.
<Gloss value>
The gloss value of the blank paper portion at 60 ° was measured with a HORIBA handy gloss meter IG-331. Table 1 shows average values obtained by measuring 10 points.

<Glossy>
After printing black solids with the Seiko Epson inkjet printer PM-G860 and drying at room temperature for 24 hours, the fluorescent light is reflected on the image area and how clearly the fluorescent light is projected. Was visually determined according to the following criteria.
(Double-circle): It is reflected very clearly.
○: The outline of the fluorescent lamp is slightly blurred but clearly visible.
Δ: The outline is slightly blurred.
X: The outline is very blurred.

<Ink absorbability>
A pattern in which fine C lines are incorporated in a solid patch of M + Y (red) is output by an ink jet printer PM-880C manufactured by Seiko Epson Corporation, and the degree of bleeding at the boundary between the fine line portion and the solid portion immediately after printing is shown below. The visual judgment was made according to the criteria.
A: The boundary is very clear, and the ink is absorbed quickly.
○: The border is slightly blurred. There is no practical problem.
Δ: The boundary is disturbed. There are practical problems.
X: The boundary is very disordered.

<Color development>
C, M, Y single color 100% and black 100% were printed with an inkjet printer PM-G860, respectively, dried at room temperature for 24 hours, and then the density of the printed part was measured. The color developability of each sample was compared with a numerical value obtained by combining the above four color densities.

<Water resistance>
Characters are printed in each color of C, M, Y, K, M + Y (red), C + Y (green), and C + M (blue) with an inkjet printer PM-G860. After drying at room temperature for 24 hours, One drop (approximately 50 μl) was dropped. Then, after drying for 24 hours at room temperature, the disorder of characters was visually determined based on the following criteria.
A: There is no disorder.
○: Slightly disturbed but no problem in practical use.
(Triangle | delta): There exists disorder and it is a problem in practical use.
X: Disturbance is remarkable.

<Humidity resistance>
A human image was printed with an inkjet printer PM-G860, dried at room temperature for 24 hours, and then 40 ° C. and 85% R.D. H. And left to stand for 24 hours, and compared with an image not subjected to the processing described on the left, the degree of bleeding was visually determined according to the following criteria.
A: No change in human skin color.
○: A slight change in human skin color is observed, but there is no practical problem.
(Triangle | delta): The color of a person's skin has changed and it is a problem practically.
X: There is a great change in the color of human skin.

<Productivity>
The following two items were evaluated.
<Drying time of coating liquid>
The time required for drying after application of the ink-receiving layer coating solution described in conjunction with the description of the method for preparing each sample was compared. The shorter the time required for drying, the higher the line speed, which means higher productivity.
<Coating defects in the coating layer>
Twenty A4 size samples were observed to observe the occurrence of coating defects, and visually judged based on the following criteria.
(Double-circle): There is no coating defect and it is very excellent.
○: There are coating defects, but there are no more than two, and these coating defects are affected by dust and the like during coating, and there is no problem as a coating solution.
(Triangle | delta): There are three or more application | coating defects of factors other than dust, and it is a level which becomes a problem practically as a coating liquid.
X: A coating defect occurs in all papers, and is not practical.

  In the recording material 9, crystals of boric acid and borax were formed after coating and drying for the undercoat layer, and the ink receiving layer was coated thereon, but the surface was rough and cracks were locally generated. In the recording materials 10 and 11, which are comparative examples using latex having a low MFT for the undercoat layer, cracks occurred when the ink receiving layer was applied. This is probably because the amount of boric acid released into the ink receiving layer was small. In the recording material 12 in which the alkali was not added to the undercoat layer coating solution, the coating surface was remarkably disturbed when the undercoat layer coating solution was applied. This is probably because the wet coating amount of the undercoat layer coating solution was too large. Furthermore, although an ink receiving layer was applied, the disturbance of the undercoat layer could not be covered. As a result, glossiness decreased. The recording material 13 with no undercoat layer and the addition of orthoboric acid as a cross-linking agent in the ink receiving layer has no problem in print quality, gloss, etc., but takes a long drying time when the ink receiving layer is applied. Therefore, it can be judged that productivity is low. In the recording material 14, gelatin was used as a binder for the undercoat layer, but glossiness, water resistance, and moisture resistance were insufficient. This is considered to be because the boric acid release rate was lowered because a continuous film was formed after applying and drying the coating solution for the undercoat layer, and a sufficient amount of boric acid was not supplied to the ink receiving layer. In the recording material 15, vapor phase method silica was added to increase the viscosity of the undercoat layer coating solution. As a result, the water-dispersible resin of the present invention was insufficient as a finely dispersed vapor-phase silica binder, and cracks occurred when the undercoat layer coating solution was dried. In the recording material 16 using inorganic fine particles having an average secondary particle diameter exceeding 500 nm for the undercoat layer, glossiness and color developability were lowered. In addition, the water resistance and moisture resistance of the image also decreased.

  From the above results, according to the present invention, it is possible to provide an ink jet recording material having high glossiness, excellent ink absorbability and color developability, and excellent water resistance and moisture bleeding resistance with high productivity. It becomes.

Claims (1)

  An undercoat layer coating solution containing a water-dispersible resin having a minimum film-forming temperature of 40 ° C. or higher, an alkali agent, and boric acid or a derivative thereof on a non-water-absorbing support and substantially free of inorganic fine particles. After coating, an ink receiving layer coating liquid mainly containing inorganic fine particles having an average secondary particle diameter of 500 nm or less and containing polyvinyl alcohol or a derivative thereof as a binder of the inorganic fine particles is applied. A method for producing an inkjet recording material.