JP2010194949A - Method for manufacturing inkjet recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an inkjet recording medium excelling in flaw resistance without worsening brittleness. <P>SOLUTION: The method for manufacturing the inkjet recording medium includes a process for forming an ink receiving layer by crosslinking and curing a coating layer formed by applying, on a support body, a first liquid containing inorganic particles, water-soluble resin and a boron compound. Crosslinking and curing are performed by applying a second liquid of pH 7.1-8.5 (1) at the same time as application of the first liquid, or (2) before the coating layer shows a decreasing rate of drying in the middle of drying the coating layer formed by applying the first liquid, and drying the second liquid and further applying a third liquid of pH 7.1 or higher after the coating layer formed by applying the second liquid is dried at the decreasing rate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an inkjet recording medium.

In recent years, with the rapid development of the information industry, various information processing systems have been developed, and recording methods and apparatuses suitable for the information systems have been developed and put into practical use.
Among the above recording methods, the inkjet recording method is capable of recording on a variety of recording materials, the hardware (device) is relatively inexpensive, compact, and excellent in quietness. Of course, it has been widely used in so-called home use.

In addition, with the recent increase in resolution of inkjet printers, it has become possible to obtain so-called photographic-like high-quality recorded matter. Furthermore, with the development of hardware (devices), various recording sheets for ink jet recording have been developed.
The characteristics required for the recording sheet for ink jet recording are generally (1) fast drying (high ink absorption speed), and (2) ink dot diameter is appropriate and uniform. (No blurring), (3) good graininess, (4) high dot roundness, (5) high color density, (6) high chroma (dullness) (7) The light resistance and water resistance of the printed portion are good, (8) the whiteness of the recording sheet is high, and (9) the recording sheet has good storage stability (yellow during long-term storage). (10) It is difficult to deform, has good dimensional stability (curl is sufficiently small), and (11) has good hard running performance. And so on. In addition to the above properties, glossy, surface smoothness, photographic paper-like texture similar to silver salt photography, etc. can be used for photo glossy paper used for the purpose of obtaining so-called photo-like high-quality recorded matter. Required.

For example, as an ink jet recording medium with improved cracking, density, and gloss, the ink receiving layer contains inorganic fine particles, a water-soluble resin, and a boron compound, and a basic solution having a pH of 8 or more is simultaneously applied to (1) application of the receiving layer. An ink jet recording medium is disclosed in which (2) the receiving layer is applied before the rate-decreasing drying, and (3) the receiving layer is applied after coating and drying (see, for example, Patent Document 1).
In addition, as an ink jet recording medium having improved surface and ink absorbability, an ink jet recording medium in which a basic solution is applied after drying of the receiving layer is disclosed (for example, see Patent Document 2).

JP 2003-191607 A JP 2008-183824 A

In Patent Document 1, a basic solution is applied to the ink receiving layer either before the ink-receiving layer is dried at a reduced rate ((1), (2)) or after the ink-receiving layer is applied and dried. Although improvements in cracking, density and gloss are described, further improvements in brittleness and scratch resistance are desired.
Further, although Patent Document 2 is expected to have an effect of improving the surface shape and ink absorbability, further improvement is desired for brittleness and scratch resistance.
The present invention has been made in view of the above points, and an object of the present invention is to provide an ink jet recording medium manufacturing method having excellent scratch resistance without deteriorating brittleness.

<1>
A step of cross-linking and curing an application layer formed by applying a first liquid containing inorganic fine particles, a water-soluble resin, and a boron compound on a support to form an ink receiving layer, (1) At the same time that the first liquid is applied, or (2) either during the drying of the coating layer formed by applying the first liquid and before the coating layer exhibits reduced-rate drying. At this time, a second liquid having a pH of 7.1 to 8.5 is applied, dried, and further, after the coating layer formed by applying the second liquid is subjected to the rate-decreasing drying, the second liquid having a pH of 7.1 or higher is applied. 3. A method for producing an ink jet recording medium, which is performed by applying the liquid (3).
<2>
The method for producing an ink jet recording medium according to <1>, wherein the pH of the third liquid is 8.0 or more.
<3>
The second liquid or the third liquid contains a basic substance, and the basic substance is at least one selected from ammonia, a primary amine, a secondary amine, and a tertiary amine. The method for producing an inkjet recording medium according to <1> or <2> above, wherein:
<4>
The inkjet recording medium manufactured with the manufacturing method of any one of said <1>-<3>.

  According to the present invention, it is possible to provide an ink jet recording medium manufacturing method having excellent scratch resistance without deteriorating brittleness.

  The method for producing an inkjet recording medium of the present invention is formed by applying a first liquid containing inorganic fine particles, a water-soluble resin, and a boron compound (hereinafter also referred to as a first coating liquid) on a support. A step of forming an ink receiving layer by crosslinking and curing the applied layer, wherein (1) the first liquid is applied and (2) the first liquid is applied. During the drying of the coating layer, before the coating layer exhibits reduced rate drying, the second liquid having a pH of 7.1 to 8.5 is applied, dried, and further It is characterized by being performed by applying a third liquid having a pH of 7.1 or higher after the coating layer formed by applying the liquid 2 is dried at a reduced rate.

  In the method for producing an inkjet recording medium of the present invention, a basic solution is applied before and after the drying rate reduction of the coating layer, respectively. By applying a basic solution after rate drying and re-crosslinking, application of the basic solution after rate-reducing drying promotes cross-linking of the coating layer surface, thus improving scratch resistance without deteriorating brittleness. be able to.

  The ink receiving layer formed by the method for producing an inkjet recording medium of the present invention is obtained by crosslinking and curing a coating layer formed by applying at least a first liquid containing inorganic fine particles, a water-soluble resin, and a boron compound. It consists of layers.

  Hereinafter, the components contained in each of the first liquid, the second liquid, and the third liquid constituting the ink receiving layer in the present invention will be described.

~ First liquid ~
(Inorganic fine particles)
The first liquid constituting the ink receiving layer in the present invention contains at least one kind of inorganic fine particles. The inorganic fine particles form a porous structure when the ink receiving layer is formed, and have a role of improving ink absorption performance.
In particular, if the solid content of the inorganic fine particles in the ink receiving layer is 50% by mass or more, more preferably more than 60% by mass, it is possible to form a more favorable porous structure, and sufficient ink absorption. This is preferable because an ink jet recording medium having the properties can be obtained. Here, the solid content in the ink receiving layer of the inorganic fine particles is a content calculated based on components other than water in the composition constituting the ink receiving layer.

Examples of the inorganic fine particles include gas phase method silica, hydrous silica fine particles, colloidal silica, titanium dioxide, barium sulfate, calcium silicate, zeolite, kaolinite, halloysite, mica, talc, calcium carbonate, magnesium carbonate, calcium sulfate, boehmite, pseudo Examples thereof include boehmite. These may be used alone or in combination of two or more.
Among these, gas phase method silica is preferable, and when the gas phase method silica and other inorganic fine particles are used in combination, the content of the gas phase method silica in the total inorganic fine particles is preferably 90% by mass or more, More preferably, it is 95 mass% or more.

  Here, the silica fine particles are generally roughly classified into wet method particles and dry method (gas phase method) particles according to the production method. In the above wet method, a method is mainly used in which activated silica is produced by acid decomposition of a silicate, and this is appropriately polymerized and agglomerated and precipitated to obtain hydrous silica. On the other hand, the gas phase method is a method by high-temperature gas phase hydrolysis of silicon halide (flame hydrolysis method), a method in which silica sand and coke are heated and reduced by an arc in an electric furnace and oxidized with air. The method of obtaining anhydrous silica by the (arc method) is the mainstream, and the “gas phase method silica” means anhydrous silica fine particles obtained by the gas phase method.

The above-mentioned gas phase method silica is different from the above-mentioned hydrous silica in the density of silanol groups on the surface, the presence or absence of vacancies, etc., and shows different properties, but is suitable for forming a three-dimensional structure with high porosity. . The reason for this is not clear, but in the case of hydrous silica, the density of silanol groups on the surface of the fine particles is high at 5 to 8 / nm ² , and the silica fine particles tend to aggregate closely (aggregate). In the case of the method silica, the density of silanol groups on the surface of the fine particles is 2 to 3 / nm ² , so that it is sparse soft aggregation (flocculate), and as a result, it is assumed that the structure has a high porosity. Is done.

  Vapor phase silica has a particularly large specific surface area, so it has high ink absorption and retention efficiency, and its refractive index is low, so if it is dispersed to an appropriate particle size, it will provide transparency to the ink receiving layer. And high color density and good color developability can be obtained. The transparency of the ink-receiving layer is not only for applications that require transparency, such as OHP, but also for high color density and good color development gloss even when applied to recording sheets such as photo glossy paper. Is important.

  The average primary particle diameter of the vapor phase silica is preferably 20 nm or less, more preferably 10 nm or less, and most preferably 3 to 10 nm. Since the gas phase method silica easily adheres to each other by hydrogen bonding by a silanol group, a structure having a large porosity can be formed when the average primary particle diameter is 20 nm or less.

  The first coating liquid in the present invention contains inorganic fine particles, and the content of the inorganic fine particles in the first coating liquid is not particularly limited, but is 50 to 90 with respect to the total solid content of the first coating liquid. It is preferable that it is mass%, and it is more preferable that it is 60-85 mass%.

(Water-soluble resin)
The first liquid constituting the ink receiving layer in the invention contains at least one water-soluble resin.
Examples of the water-soluble resin include polyvinyl alcohol (PVA), polyvinyl acetal, cellulose resin [methyl cellulose (MC), ethyl cellulose (EC), hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), etc.], chitins, chitosans, Starch: Polyethylene oxide (PEO), polypropylene oxide (PPO), polyethylene glycol (PEG), polyvinyl ether (PVE), which is a resin having an ether bond; Polyacrylamide (PAAM), a resin having an amide group or an amide bond, polyvinyl Examples include pyrrolidone (PVP) and polyacrylates, maleic resins, alginates, and gelatins having a carboxyl group as a dissociable group. These may be used alone or in combination of two or more.

  Among these, polyvinyl alcohol is preferable. When the polyvinyl alcohol and other water-soluble resin are used in combination, the content of polyvinyl alcohol in the total water-soluble resin is preferably 90% by mass or more, and 95% by mass or more. More preferably.

Examples of the polyvinyl alcohol include cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, silanol-modified polyvinyl alcohol, and other polyvinyl alcohol derivatives in addition to polyvinyl alcohol (PVA).
The said water-soluble resin may be used individually by 1 type, and may use 2 or more types together.

The PVA has a hydroxyl group in its structural unit, and this hydroxyl group and the silanol group on the surface of the silica fine particle form a hydrogen bond, and it is easy to form a three-dimensional network structure in which the secondary particle of the silica fine particle is a chain unit. To do. This is considered to be because a porous structure ink receiving layer having a high porosity can be formed by forming the three-dimensional network structure.
In ink-jet recording, the porous ink-receiving layer obtained as described above can absorb ink rapidly by capillary action, and can form dots with good roundness without ink blurring.

  As the content of the water-soluble resin, the decrease in the film strength due to the insufficient content and the cracking at the time of drying are prevented, and further, the excessive content causes the voids to be easily blocked by the resin. From the viewpoint of preventing the ink absorbency from being lowered due to the decrease in the porosity, the amount is preferably 9 to 40% by mass, and more preferably 12 to 33% by mass with respect to the total solid mass of the ink receiving layer.

  The water-soluble resin preferably has a number average degree of polymerization of 1800 or more, more preferably 2000 or more, from the viewpoint of preventing cracks. Of these, PVA having a saponification degree of 88% or more is preferable, PVA having a saponification degree of 95% or more is more preferable, and PVA having a saponification degree of 98% or more is particularly preferable from the viewpoint of transparency and viscosity of the ink receiving layer coating solution.

-Content ratio of inorganic fine particles and water-soluble resin-
The content ratio of inorganic fine particles (for example, vapor phase method silica; i) and water-soluble resin (for example, polyvinyl alcohol; p) [PB ratio (i: p), mass of inorganic fine particles relative to 1 part by mass of water-soluble resin] is The film structure of the ink receiving layer is also greatly affected. That is, as the PB ratio increases, the porosity, pore volume, and surface area (per unit mass) increase.
Specifically, as the PB ratio (i: p), it is possible to prevent a decrease in film strength caused by the PB ratio being too large, cracking during drying, and further, the PB ratio is too small. From the viewpoint of preventing the ink absorbability from decreasing due to the void being easily blocked by the water-soluble resin and decreasing the porosity, 1.5: 1 to 10: 1 is preferable.

Since stress may be applied to the ink jet recording medium when passing through the transport system of the ink jet printer, the ink receiving layer needs to have sufficient film strength. Further, when cutting into a sheet shape, the ink receiving layer needs to have sufficient film strength in order to prevent the ink receiving layer from cracking or peeling off.
In this case, the PB ratio is preferably 5: 1 or less, and preferably 2: 1 or more from the viewpoint of securing high-speed ink absorbability with an inkjet printer.

For example, a coating solution in which anhydrous silica fine particles having an average primary particle diameter of 20 nm or less and a water-soluble resin are completely dispersed in an aqueous solution at a PB ratio of 2: 1 to 5: 1 is coated on a support, and the coating layer is formed. When dried, a three-dimensional network structure is formed with the secondary particles of silica fine particles as chain units, the average pore diameter is 30 nm or less, the porosity is 50% to 80%, the pore specific volume is 0.5 ml / g or more, A translucent porous film having a specific surface area of 100 m ² / g or more can be easily formed.

(Boron compound)
The first liquid constituting the ink receiving layer in the present invention contains at least one boron compound from the viewpoint of suppressing cracking, image printing density, and glossiness. The ink-receiving layer can be formed by crosslinking the water-soluble resin with the boron compound and curing the coating layer.

The boron compound is used by being contained in the first coating liquid, and is preferably contained in a mass ratio of 0.05 to 0.50 with respect to the water-soluble resin 1, and 0.08 to 0.30. More preferably it is contained. By containing the boron compound in the above range, the water-soluble resin can be sufficiently crosslinked to prevent cracks and the like. In addition, the print density and glossiness of the image can be improved as compared to adding a boron compound to the second coating solution.
In addition, as a density | concentration of the boron compound in a 1st coating liquid, it is preferable that it is 0.05-10 mass%, and it is more preferable that it is 0.1-7 mass%.

Examples of the boron compound include borax, boric acid, borates (for example, orthoborate, InBO ₃ , ScBO ₃ , YBO ₃ , LaBO ₃ , Mg ₃ (BO ₃ ) ₂ , Co ₃ (BO ₃ ) ₂ , two Borate (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 ) and the like.
Among these, borax, boric acid, and borate are preferable, and boric acid is more preferable in that a rapid crosslinking reaction with a water-soluble resin (particularly polyvinyl alcohol) occurs.
The said boron compound may be used individually by 1 type or in combination of 2 or more types.

  As a crosslinking agent for the water-soluble resin, compounds that can be used in combination with the boron compound include glyoxal, melamine / formaldehyde (for example, methylolmelamine, alkylated methylolmelamine), methylolurea, resol resin, polyisocyanate, epoxy resin, and the like. Can be mentioned.

Further, when gelatin is used in combination with polyvinyl alcohol as the water-soluble resin, the following compounds known as gelatin hardeners can be used in combination.
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;

Isocyanate compounds such as 1,6-hexamethylene diisocyanate; Aziridine compounds described in US Pat. Nos. 3,017,280 and 2,983,611; Carboximide compounds described in US Pat. No. 3,100,704; Glycerol triglycidyl Epoxy compounds such as ether; Ethyleneimino compounds such as 1,6-hexamethylene-N, N′-bisethyleneurea; Halogenated carboxaldehyde compounds such as mucochloric acid and mucophenoxycyclolic acid; 2,3-dihydroxy Dioxane compounds such as dioxane; chromium alum, potash alum, zirconium sulfate, chromium acetate and the like.

  The content of the boron compound in the first coating solution is preferably 0.05 to 0.50 with respect to the water-soluble resin 1 in terms of improving the film strength and preventing cracking. It is more preferable that it contains 08-0.30.

(Cationic resin)
The first liquid constituting the ink receiving layer in the invention preferably contains at least one cationic resin. The inorganic fine particles are preferably used by dispersing with a cationic resin.
The cationic resin is not particularly limited, but a water-soluble or aqueous emulsion type can be suitably used. Examples of the cationic resin include dicyan cation resin represented by dicyandiamide-formalin polycondensate, polyamine cation resin represented by dicyanamide-diethylenetriamine polycondensate, epichlorohydrin-dimethylamine addition polymer, dimethyldiallylammonium. Chloride-SO ₂ copolymer, diallylamine salt-SO ₂ copolymer, dimethyldiallylammonium chloride polymer, allylamine salt polymer, dialkylaminoethyl (meth) acrylate quaternary salt polymer, acrylamide-diallylamine salt copolymer And polycationic cationic resins such as dimethyldiallylammonium chloride, monomethyldiallylammonium chloride and polyamidine are preferred. Luzia Lil ammonium chloride, and monomethyl diallyl ammonium chloride are particularly preferred. This cationic resin may be used independently and may use 2 or more types together.

As content in the 1st coating liquid of a cationic resin, 1-30 mass parts is preferable with respect to 100 mass parts of inorganic fine particles, More preferably, it adjusts in the range of 3-20 mass parts.
As the addition amount of the cationic resin in the ink receiving layer, the cationic resin may be added in a small amount before pulverization and dispersion, and after further pulverization and dispersion until a desired particle size is obtained.

(Organic mordant)
The second and third liquids described later constituting the ink receiving layer in the present invention may be an organic mordant (hereinafter simply referred to as “mordanting agent”) in order to further improve the water resistance and aging resistance of the formed image. May be included).
As the mordant, a cationic polymer (cationic mordant) is preferable. When the mordant is present in the ink receiving layer, it interacts with a liquid ink having an anionic dye as a colorant to stabilize the colorant. Water resistance and aging blur can be improved.

When the mordant is directly added to the first coating liquid for forming the ink receiving layer, there is a concern that aggregation occurs between inorganic fine particles having an anionic charge (for example, vapor phase method silica). If a method of preparing and applying as a solution is utilized, there is no need to worry about aggregation of inorganic fine particles. Therefore, in this invention, it can contain and use in any one of the 2nd and 3rd liquid (basic solution) different from the said vapor phase method silica.
Moreover, it is preferable to use a basic mordant (for example, polyallylamine) as a mordant. By using a basic mordant, it becomes possible to play a role as a basic substance simultaneously with a role as a mordant.

As the cationic mordant, a polymer mordant having a primary to tertiary amino group or a quaternary ammonium base as a cationic group is preferably used, but a cationic non-polymer mordant may also be used. it can.
Examples of the polymer mordant include a homopolymer of a monomer having a primary to tertiary amino group and a salt thereof, or a quaternary ammonium base (mordant monomer), and the mordant monomer and other monomers (hereinafter, What is obtained as a copolymer or condensation polymer with "non-mordant polymer") is preferred. These polymer mordants can be used in any form of a water-soluble polymer or water-dispersible latex particles.

  Examples of the monomer (mordant monomer) include trimethyl-p-vinylbenzylammonium chloride, trimethyl-m-vinylbenzylammonium chloride, triethyl-p-vinylbenzylammonium chloride, triethyl-m-vinylbenzylammonium chloride, N , N-dimethyl-N-ethyl-Np-vinylbenzylammonium chloride, N, N-diethyl-N-methyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-Nn-propyl-N -P-vinylbenzylammonium chloride, N, N-dimethyl-Nn-octyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N-benzyl-Np-vinylbenzylammonium chloride, N, N-die Ru-N-benzyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N- (4-methyl) benzyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N-phenyl-N -P-vinylbenzylammonium chloride,

Trimethyl-p-vinylbenzylammonium bromide, trimethyl-m-vinylbenzylammonium bromide, trimethyl-p-vinylbenzylammonium sulfonate, trimethyl-m-vinylbenzylammonium sulfonate, trimethyl-p-vinylbenzylammonium acetate, trimethyl-m-vinyl Benzylammonium acetate, N, N, N-triethyl-N-2- (4-vinylphenyl) ethylammonium chloride, N, N, N-triethyl-N-2- (3-vinylphenyl) ethylammonium chloride, N, N-diethyl-N-methyl-N-2- (4-vinylphenyl) ethylammonium chloride, N, N-diethyl-N-methyl-N-2- (4-vinylphenyl) ethylammonium chloride Tate,

N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, N, N- Methyl chloride, ethyl chloride, methyl bromide of dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-diethylaminopropyl (meth) acrylamide , Quaternized products of ethyl bromide, methyl iodide or ethyl iodide, or sulfonates, alkyl sulfonates, acetates or alkyl carboxylates substituted for their anions.

  Specifically, for example, monomethyl diallyl ammonium chloride, trimethyl-2- (methacryloyloxy) ethylammonium chloride, triethyl-2- (methacryloyloxy) ethylammonium chloride, trimethyl-2- (acryloyloxy) ethylammonium chloride, triethyl- 2- (acryloyloxy) ethylammonium chloride, trimethyl-3- (methacryloyloxy) propylammonium chloride, triethyl-3- (methacryloyloxy) propylammonium chloride, trimethyl-2- (methacryloylamino) ethylammonium chloride, triethyl-2- (Methacryloylamino) ethylammonium chloride, trimethyl-2- (acryloylamino) ethyl Ammonium chloride, triethyl-2- (acryloylamino) ethylammonium chloride, trimethyl-3- (methacryloylamino) propylammonium chloride, triethyl-3- (methacryloylamino) propylammonium chloride, trimethyl-3- (acryloylamino) propylammonium chloride Triethyl-3- (acryloylamino) propylammonium chloride,

N, N-dimethyl-N-ethyl-2- (methacryloyloxy) ethylammonium chloride, N, N-diethyl-N-methyl-2- (methacryloyloxy) ethylammonium chloride, N, N-dimethyl-N-ethyl- 3- (acryloylamino) propylammonium chloride, trimethyl-2- (methacryloyloxy) ethylammonium bromide, trimethyl-3- (acryloylamino) propylammonium bromide, trimethyl-2- (methacryloyloxy) ethylammonium sulfonate, trimethyl-3- And (acryloylamino) propylammonium acetate.
Other examples of the copolymerizable monomer include N-vinylimidazole and N-vinyl-2-methylimidazole.

The non-mordant polymer does not contain a basic or cationic moiety such as a primary to tertiary amino group and a salt thereof, or a quaternary ammonium base, and does not interact with a dye in an inkjet ink. Or the monomer which interaction is substantially small is said.
Examples of the non-mordant monomer include (meth) acrylic acid alkyl ester; (meth) acrylic acid cycloalkyl ester such as cyclohexyl (meth) acrylate; (meth) acrylic acid aryl ester such as phenyl (meth) acrylate; Aralkyl esters such as (meth) benzyl acrylate; Aromatic vinyls such as styrene, vinyl toluene and α-methylstyrene; Vinyl esters such as vinyl acetate, vinyl propionate and vinyl versatic acid; Allyl esters such as allyl acetate Halogen-containing monomers such as vinylidene chloride and vinyl chloride; vinyl cyanide 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, for example, methyl (meth) acrylate, ethyl (meth) acrylate, (meth) Propyl acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, Examples include 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and the like.
Of these, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and hydroxyethyl methacrylate are preferable.
The non-mordant monomers can also be used singly or in combination of two or more.

  Further, as a polymer mordant, polydiallyldimethylammonium chloride, polymethacryloyloxyethyl-β-hydroxyethyldimethylammonium chloride, polyethylenimine, polyallylamine and its modified product, polyallylamine hydrochloride, polyamide-polyamine resin, cationized starch, Dicyandiamide formalin condensate, dimethyl-2-hydroxypropylammonium salt polymer, polyamidine, polyvinylamine and the like can also be mentioned as preferred, and polyallylamine and polyallylamine-modified products are particularly preferred.

  The polyallylamine-modified product is obtained by adding 2 to 50 mol% of acrylonitrile, chloromethylstyrene, TEMPO, epoxy hexane, sorbic acid or the like to polyallylamine, and preferably 5 to 5 of acrylonitrile, chloromethylstyrene, and TEMPO. It is a 10 mol% adduct, and 5 to 10 mol% TEMPO adduct of polyallylamine is particularly preferable from the viewpoint of exhibiting the effect of preventing ozone fading.

  The molecular weight of the mordant is preferably 2000 to 300000 in terms of weight average molecular weight. When the molecular weight is in the range of 2000 to 300,000, water resistance and aging resistance can be improved.

  In the present invention, the water resistance of the ink receiving layer can be improved by adding a mordant to the second liquid other than the first coating liquid. That is, when the mordant is added to the first coating solution, the mordant is cationic, so that aggregation may occur in the presence of vapor phase silica having an anionic charge on the surface. If a method of preparing the two liquids and the first coating liquid independently and applying them individually is employed, it is not necessary to consider the aggregation of inorganic fine particles, and the selection range of the mordant is expanded.

(Surfactant)
The first liquid constituting the ink receiving layer in the invention preferably contains at least one nonionic or amphoteric surfactant.
Examples of the nonionic surfactant include polyoxyalkylene alkyl ethers and polyoxyalkylene alkylphenyl ethers (for example, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene Ethylene nonylphenyl ether), oxyethylene / oxypropylene block copolymer, sorbitan fatty acid esters (for example, sorbitan monolaurate, sorbitan monooleate, sorbitan trioleate, etc.), polyoxyethylene sorbitan fatty acid esters (for example, polyoxyethylene) Sorbitan monolaurate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan Lyolate, etc.), polyoxyethylene sorbitol fatty acid esters (eg, polyoxyethylene sorbitol tetraoleate), glycerin fatty acid esters (eg, glycerol monooleate), polyoxyethylene glycerin fatty acid esters (polyoxymonostearate) Ethylene glycerin, monooleic acid polyoxyethylene glycerin, etc.), polyoxyethylene fatty acid esters (polyethylene glycol monolaurate, polyethylene glycol monooleate, etc.), polyoxyethylene alkylamine, etc., and polyoxyalkylene alkyl ethers are preferable.
Moreover, the said nonionic surfactant may be used independently and may use 2 or more types together.

  Examples of the amphoteric surfactants include amino acid type, carboxyammonium betaine type, sulfoammonium betaine type, ammonium sulfate betaine type, imidazolium betaine type, etc., for example, U.S. Pat. No. 3,843,368, Those described in JP-A-59-49535, JP-A-63-236546, JP-A-5-303205, JP-A-8-262742, and JP-A-10-282619 can be suitably used. As the amphoteric surfactant, an amino acid type amphoteric surfactant is preferable, and as the amino acid type amphoteric surfactant, as described in JP-A-5-303205, for example, an amino acid (glycine, glutamic acid, Histidine acid etc.) and N-aminoacyl acids and salts thereof into which long chain acyl groups have been introduced. The amphoteric surfactants may be used alone or in combination of two or more, and may be used in combination with the nonionic surfactant.

  The content of the nonionic or amphoteric surfactant in the first coating solution is preferably 0.01 to 1% by mass, particularly preferably 0.03 to 0.6% by mass.

(High boiling point organic solvent)
By including the nonionic or amphoteric surfactant and the high boiling point organic solvent in the first coating liquid constituting the ink receiving layer in the invention, the curl of the ink jet recording medium can be kept flat.
The high-boiling organic solvent is preferably water-soluble, and examples of the water-soluble high-boiling organic solvent include ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, glycerin, diethylene glycol monobutyl ether (DEGMBE), and triethylene. Glycol monobutyl ether, glycerin monomethyl ether, 1,2,3-butanetriol, 1,2,4-butanetriol, 1,2,4-pentanetriol, 1,2,6-hexanetriol, thiodiglycol, triethanol Examples include alcohols such as amines and polyethylene glycol (weight average molecular weight of 400 or less), and diethylene glycol monobutyl ether (DEGMBE) is preferable.

  As content in the coating liquid of the said high boiling point organic solvent, 0.05-1 mass% is preferable, Most preferably, it is 0.1-0.6 mass%.

(Other ingredients)
The 1st liquid which comprises the ink receiving layer in this invention may contain the following component as needed.
For the purpose of suppressing deterioration of the coloring material contained in the ink, various kinds of ultraviolet absorbers, antioxidants, anti-fading agents such as singlet oxygen quenchers may be included.
Examples of the ultraviolet absorber include cinnamic acid derivatives, benzophenone derivatives, benzotriazolylphenol derivatives, and the like.

  The anti-fading agent may be used alone or in combination of two or more. This anti-fading agent may be water-solubilized, dispersed, emulsified, or included in microcapsules. The addition amount of the anti-fading agent is preferably 0.01 to 10% by mass of the first coating solution.

The first liquid constituting the ink receiving layer may contain various inorganic salts and acids, alkalis and the like as pH adjusting agents for the purpose of enhancing the dispersibility of the inorganic fine particles.
Further, for the purpose of suppressing surface frictional charge and peeling charge, the metal oxide fine particles having electronic conductivity may contain various matting agents for the purpose of reducing the surface frictional characteristics.

In the present invention, for example, gas phase method silica (inorganic fine particles), polyvinyl alcohol (water-soluble resin), cationic resin, boric acid, nonionic or amphoteric surfactant, and a high-boiling organic solvent are included. One liquid (first coating liquid) can be prepared as follows.
That is, vapor phase silica is added to water, a cationic resin is further added, and dispersed with a high-pressure homogenizer, a sand mill, etc., boric acid is added, and polyvinyl alcohol aqueous solution (for example, 1 / of vapor phase silica) is added. And a non-ionic surfactant or an amphoteric surfactant and a high-boiling organic solvent are added, and the mixture is stirred. The obtained coating solution is a uniform sol, and a porous layer having a three-dimensional network structure can be formed by coating this on a support by the following coating method.
Moreover, partial gelatinization of polyvinyl alcohol can be prevented by adding polyvinyl alcohol after diluting boric acid as described above.

  In the present invention, the first coating solution is preferably an acidic solution, and the pH of the first coating solution is preferably 5.0 or less, more preferably 4.5 or less. More preferably, it is 0 or less. The pH of the first coating solution can be adjusted by appropriately selecting the type and amount of the cationic resin. Moreover, you may adjust by adding an organic or inorganic acid. When the pH of the first coating solution is 5.0 or less, the crosslinking reaction of the water-soluble resin by the boron compound in the first coating solution can be more sufficiently suppressed.

The first coating solution can be applied by a known coating method 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, or a bar coater.
The coating amount of the first coating solution, it is common is 50 to 300 g / ^{m 2,} is preferably 100 to 250 g / ^{m 2.}

~ Second liquid ~
The second liquid is a basic solution having a pH of 7.1 to 8.5. If the pH of the second liquid is less than 7.1, the tendency of causing scratches that cause a problem in the ink receiving layer becomes remarkable. In addition, when the pH of the second liquid exceeds 8.5, the tendency for the brittleness to deteriorate becomes significant.
Among these, from the viewpoint of scratch resistance, the pH of the second liquid is preferably 7.1 to 8.0, and more preferably 7.5 to 8.0.
The pH of the second liquid can be adjusted by adding a basic substance.
Examples of basic substances added to the second liquid include ammonia, primary amines (ethylamine, polyallylamine, polyvinylamine, etc., preferably polyallylamine), secondary amines (dimethylamine), and tertiary substances. Examples thereof include tertiary amines (N-ethyl-N-methylbutylamine, triethylamine, etc.), alkali metal or alkaline earth metal hydroxides and / or salts of these basic substances (preferably ammonium salts). In addition, other polyvalent amines such as ethylenediamine may be added.
Among these basic substances, at least one selected from ammonia and primary to tertiary amines is preferable from the viewpoints of performance such as scratch resistance, wet heat bleeding and storage stability, and further, ammonia, polyallylamine, and ammonium salts are preferred. preferable.

In the above aspect (2), it is preferable to apply the second liquid before the application layer after application of the first application liquid exhibits reduced-rate drying.
Here, “before the coating layer comes to show reduced-rate drying” usually refers to several minutes immediately after the application of the first coating solution, and during this period, the content of the solvent in the coated coating layer is included. Constant rate drying is a phenomenon in which the amount decreases in proportion to time. About the time which shows this constant rate drying, it describes in chemical engineering handbook (p.707-712, Maruzen Co., Ltd. issue, October 25, 1980).

  As described above, after the application of the first coating solution, it is dried until the coating layer exhibits reduced-rate drying, and the drying is generally performed at 40 to 180 ° C. for 0.5 to 10 minutes (preferably, 0.5 to 5 minutes). The drying time naturally varies depending on the coating amount, but the above range is appropriate.

  As a method for applying the second liquid before the coating layer exhibits reduced drying, (1) a method of further coating the second liquid on the coating layer, and (2) a method such as spraying. Examples of the spraying method include (3) a method in which the support on which the coating layer is formed is immersed in the second liquid.

  In the method (1), examples of the 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 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 grant (application) amount of the second liquid, it is common is 5 to 50 g / ^{m 2,} is preferably 10 to 30 g / ^{m 2.}

Moreover, there exists the aspect of said (1) to which the said 2nd liquid is provided simultaneously with apply | coating a 1st coating liquid.
In this case, the first coating liquid and the second liquid are applied simultaneously (multilayer coating) on the support so that the first coating liquid is in contact with the support, and then dried and cured to be described later. The ink receiving layer before applying the third liquid can be formed.

The simultaneous application (multilayer application) can be performed, for example, by an application method using an extrusion die coater or a curtain flow coater. After the simultaneous application, the formed application layer is dried. In this case, the drying is generally performed by heating the application layer at 40 to 150 ° C. for 0.5 to 10 minutes, preferably 40 to 100. It is carried out by heating at a temperature of 0.5 to 5 minutes.
In this invention, since a boron compound is used, it is preferable to heat at 60-100 degreeC for 5 to 20 minutes.

  When the above simultaneous coating (multilayer coating) is performed by, for example, an extrusion die coater, two types of coating liquid discharged at the same time are formed near the discharge port of the extrusion die coater, that is, before moving onto the support. In this state, a multilayer coating is applied on the support. Since the two-layer coating liquid layered before coating tends to cause a crosslinking reaction at the interface between the two liquids when transferred to the support, the two liquids to be ejected are mixed in the vicinity of the discharge port of the extrusion die coater. This may increase the viscosity and hinder the application operation. Therefore, when applying simultaneously as described above, the barrier layer liquid (intermediate layer liquid) made of a material that does not react with the crosslinking agent is applied together with the application of the first coating liquid and the second liquid (basic solution). It is preferable to apply a simultaneous triple layer by interposing between two liquids.

The barrier layer liquid can be selected without particular limitation as long as it does not react with the boron compound and can form a liquid film. For example, an aqueous solution containing a trace amount of water-soluble resin that does not react with a boron compound, water, and the like can be given. The water-soluble resin is used in consideration of coatability for the purpose of a thickener and the like, for example, hydroxypropylmethylcellulose, methylcellulose, hydroxyethylmethylcellulose, polyvinylpyrrolidone, gelatin And the like.
The barrier layer solution may contain the above mordant.

~ Third liquid ~
The third liquid needs to be a basic solution having a pH of 7.1 or higher. If the pH of the third liquid is less than 7.1, scratches on the obtained ink jet recording medium are likely to occur. The pH of the third liquid is preferably 7.5 or higher, more preferably 8.0 or higher, and particularly preferably 8.5 or higher. The higher the pH value, the better the scratch resistance.
In addition, pH adjustment of this 3rd liquid can be adjusted by adding a basic substance.
Examples of the basic substance added to the third liquid include the same basic substances as those added to the second liquid. Moreover, a preferable example is also the same.
Among these basic substances, ammonia and primary to tertiary amines are preferable from the viewpoint of performance such as scratch resistance, wet heat bleeding and storage stability, and ammonia, polyallylamine and ammonium salts are more preferable.

As the timing of application of the third liquid, it is preferable to apply the liquid after the first coating liquid and the second liquid are applied and further dried (after decelerating drying).
Here, “after the rate-decreasing drying” is when the coating layer after the first coating solution and the second solution are applied is dried and the end point of the rate-decreasing drying is passed from the constant rate drying to the rate-decreasing drying. After the end point of drying.
“Drying end point” refers to after evaporation of volatile components including water from the coating layer.

  After application of the third liquid, drying is generally performed at 40 to 180 ° C. for 0.5 to 10 minutes (preferably 60 to 100 ° C. for 0.5 to 10 minutes. The drying time naturally depends on the applied amount. However, the above range is appropriate.

  Examples of the third liquid application method include the same method as the second liquid application method, and the preferred method is also the same.

The amount of application (application) of the third liquid is not particularly limited, but is preferably 5 to 50 g / m ² and more preferably 10 to 30 g / m ² from the viewpoint of improving the scratch resistance of the ink receiving layer. Is more preferable.

  Moreover, water, an organic solvent, or these mixed solvents can be used as a solvent which can be used in this invention. Examples of the organic solvent that can be used for the application (particularly coating) include alcohols such as methanol, ethanol, n-propanol, i-propanol, and methoxypropanol, ketones such as acetone and methyl ethyl ketone, tetrahydrofuran, acetonitrile, and ethyl acetate. , Toluene and the like.

  After the ink receiving layer is formed on the support, the ink receiving layer is subjected to, for example, super calender, gloss calender, etc., and is subjected to calender treatment through the roll nip under heat and pressure, so that surface smoothness, glossiness, It is possible to improve transparency and coating strength. However, the calendar process may cause a decrease in the porosity (that is, the ink absorptivity may be decreased), so it is necessary to set conditions under which the decrease in the porosity is small.

As roll temperature in the case of performing a calendar process, 30-150 degreeC is preferable and 40-100 degreeC is more preferable.
Moreover, as a linear pressure between rolls at the time of a calendar process, 50-400 kg / cm is preferable and 100-200 kg / cm is more preferable.

In the case of ink jet recording, the thickness of the ink receiving layer needs to have an absorption capacity sufficient to absorb all of the droplets, and therefore needs to be determined in relation to the porosity in the layer. For example, if the ink amount is 8 nL / mm ² and the porosity is 60%, a film having a layer thickness of about 15 μm or more is required.
Considering this point, in the case of ink jet recording, the layer thickness of the ink receiving layer is preferably 10 to 50 μm.

The pore diameter of the ink receiving layer is preferably 0.005 to 0.030 μm, more preferably 0.01 to 0.025 μm in terms of median diameter.
The porosity and the median diameter of the pores can be measured using a mercury porosimeter (trade name: Bore Sizer 9320-PC2, manufactured by Shimadzu Corporation).

In addition, the ink receiving layer is preferably excellent in transparency, as a guide, the haze value when the ink receiving layer is formed on a transparent film support is preferably 30% or less, More preferably, it is 20% or less.
The haze value can be measured using a haze meter (HGM-2DP: Suga Test Instruments Co., Ltd.).

<Support>
As the support in the present invention, any of a transparent support made of a transparent material such as plastic and 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 for the transparent support is preferably a material that is transparent and can withstand radiant heat when used in an OHP or a 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 of handleability.

  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, the following supports are mentioned.

For example, high-gloss paper supports such as art paper, coated paper, cast-coated paper, silver salt photographic support, RC paper, baryta paper, etc .; polyesters such as polyethylene terephthalate (PET), nitrocellulose , Cellulose esters such as cellulose acetate and cellulose acetate butyrate, and plastic films such as polysulfone, polyphenylene oxide, polyimide, polycarbonate, polyamide, etc., were made opaque by adding a white pigment or the like (may be subjected to surface calendering treatment) .) High gloss film; Or, a polyolefin coating layer containing or not containing white pigment is provided on the surface of the above paper support, transparent support or high gloss film containing white pigment. Support.
Furthermore, 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 paper support will be described in detail.
The base paper is made from wood pulp as a main raw material and, if necessary, paper using synthetic pulp such as polypropylene or synthetic fibers such as nylon or polyester in addition to wood pulp. 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 a 24 mesh residual mass% defined by JIS P-8207 and a 42 mesh fraction. 30 to 70% of the sum with the mass% of 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).
Furthermore, the base paper stiffness 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.

  The polyethylene covering the front and back surfaces of the base paper is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but some other LLDPE, polypropylene, etc. can also be used.

In particular, the polyethylene layer on the side that forms the ink receiving layer is added with rutile or anatase type titanium oxide, fluorescent whitening agent, ultramarine, and 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 examples of components that can be added to the back coat layer include a white pigment, an aqueous binder, and other components.
Examples of white pigments contained in the backcoat layer include light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, and aluminum silicate. , Diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, colloidal alumina, pseudoboehmite, aluminum hydroxide, alumina, lithopone, zeolite, hydrous halloysite, magnesium carbonate, magnesium hydroxide, white inorganic pigment, styrene And organic pigments such as polyethylene plastic pigments, acrylic plastic pigments, polyethylene, microcapsules, urea resins, and melamine resins.

Examples of the aqueous binder used in the back coat layer include styrene / maleate copolymer, styrene / acrylate copolymer, polyvinyl alcohol, silanol-modified polyvinyl alcohol, starch, cationized starch, casein, gelatin, carboxy Examples thereof include water-soluble polymers such as methyl cellulose, hydroxyethyl cellulose, and polyvinyl pyrrolidone, and water-dispersible polymers such as styrene butadiene latex and acrylic emulsion.
Examples of other components contained in the backcoat layer include an antifoaming agent, an antifoaming agent, a dye, a fluorescent brightening agent, a preservative, and a water-proofing agent.

<Others>
The ink jet recording medium of the present invention may further have an ink solvent absorbing layer, an intermediate layer, a protective layer and the like in addition to the ink receiving layer. 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 layer.

  A polymer fine particle dispersion may be added to a constituent layer (for example, an ink receiving layer or a back coat layer) of the inkjet recording medium of the present invention. This polymer fine particle dispersion is used for the purpose of improving film properties such as dimensional stabilization, curling prevention, adhesion prevention, and film cracking prevention. The polymer fine particle dispersion is described in JP-A-62-245258 and JP-A-10-228076. If a polymer fine particle dispersion having a low glass transition temperature (40 ° C. or lower) is added to the layer containing the mordant, cracking and curling of the layer can be prevented. Further, even when a polymer fine particle dispersion having a high glass transition temperature is added to the back layer, curling can be prevented.

  The ink receiving layer may be provided only on one side of the support, or may be provided on both sides of the support for the purpose of preventing deformation such as curling. When the ink receiving layer is provided only on one side of the support, the anti-reflection film may be provided on the opposite side surface or both sides for the purpose of increasing light transmission. .

  In addition, by applying boric acid or a boron compound to the surface of the support on the side where the ink receiving layer is provided, and forming an ink receiving layer thereon, the glossiness and surface smoothness of the ink receiving layer can be improved. In addition, it is possible to suppress aging blurring of an image after printing in a high temperature and high humidity environment.

  The present invention will be described more specifically with reference to the following examples. The scope of the present invention is not limited to the specific examples shown below. In the examples, “%” represents “% by mass” unless otherwise specified, the number following “WM” represents “weight average molecular weight”, and “polymerization degree” represents “weight average polymerization degree”. .

[Example 1]
-Production of support-
After applying corona discharge treatment to art paper (OK Kanfuji; Oji Paper Co., Ltd.) weighing 186 g / m ² , high-density polyethylene was coated to a thickness of 19 μm using a melt extruder, and the mat surface (Hereinafter, the resin layer surface is referred to as “back surface”). The resin layer on the back side is further subjected to corona discharge treatment, and then, as an antistatic agent, aluminum oxide (alumina sol 100, manufactured by Nissan Chemical Industries, Ltd.) and silicon dioxide (Snowtex O, manufactured by Nissan Chemical Industries, Ltd.) ) Was dispersed in water at a ratio (mass ratio) of 1: 2 so that the dry mass was 0.2 g / m ² .

  Further, after the corona discharge treatment is performed on the felt surface (surface) side where the resin layer is not provided, anatase type titanium dioxide 10%, a trace amount of ultramarine blue, and a fluorescent whitening agent 0.01% (vs. polyethylene) Low-density polyethylene containing MFR (melt flow rate) 3.8, melt-extruded to a thickness of 24 μm using a melt extruder to form a highly glossy thermoplastic resin layer on the surface side of the base paper (Hereinafter, this high-gloss surface is referred to as the “front side”) and used as a support. The front surface of the support was used after corona discharge treatment before coating the coating solution.

-Preparation of first coating liquid-
Vapor phase silica fine particles are mixed with ion-exchanged water having the following composition, monomethyldiallylammonium chloride is further mixed therewith, and nanomer LA31 (manufactured by Nanomer Co., Ltd.) is used twice at a pressure of 500 kg / m ^2. Processed. Thereafter, stirring was performed for 60 minutes, and a boric acid solution (5.3%) was added with stirring. Thereto, a 7% aqueous solution of polyvinyl alcohol having the following composition was added with stirring, and polyoxyethylene lauryl ether and diethylene glycol monobutyl ether were further added to prepare a coating solution for an ink-receiving layer having a pH of 3.5. The mass ratio of the inorganic fine particles to the water-soluble resin (inorganic fine particles: water-soluble resin) was 4.5: 1.

[Composition of the first coating solution]
・ Ion exchange water: 167.5kg
・ Gas phase silica fine particles (inorganic fine particles) ... 30kg
(Average primary particle diameter 7 nm, Leorosil QS-30, manufactured by Tokuyama Corporation)
・ Monomethyldiallylammonium chloride: 2.5kg
(Cationic resin; Nittobo Co., Ltd., PAS-M-1, WM: 20,000, solid content concentration: 60%)
・ Boric acid (5.3% aqueous solution) 23.0 kg
・ Polyvinyl alcohol (7% aqueous solution) ... 95.18kg
(PVA124, manufactured by Kuraray Co., Ltd., saponification degree 98.5%, polymerization degree 2400)
・ Polyoxyethylene lauryl ether: 18.22kg
(Nonionic surfactant: Emulgen 109P (2% aqueous solution), manufactured by Kao Corporation)
・ Diethylene glycol monobutyl ether (DEGMBE): 1.09 kg
(High boiling point organic solvent)

―Preparation of inkjet recording media―
The first coating solution obtained from the above was applied to the front surface of the support at an application amount of 200 g / m ² using an extrusion die coater (application process), and 80 ° C. (wind speed of 3 to 3) with a hot air dryer. 8 m / sec) and dried until the solid content concentration of the coating layer reached 20%. The coating layer showed constant rate drying during this period. Immediately after that, it was immersed in a basic solution (second liquid) having the following composition for 30 seconds to adhere 20 g / m ² on the coating layer (basic solution applying step before rate-decreasing drying). Then, it was further dried at 80 ° C. for 10 minutes (drying step).
And after drying, it was further immersed in a basic solution (third liquid) having the following composition for 30 seconds to adhere 20 g / m ² on the coating layer (basic solution application step after reduced drying). It was dried at 80 ° C. for 10 minutes (drying process). Thus, an ink jet recording medium provided with an ink receiving layer having a dry film thickness of 35 μm was produced.

[Basic solution]
・ Ion-exchanged water 34.7kg
・ Boric acid 0.3kg
・ Polyoxyethylene lauryl ether 5.0kg
(Nonionic surfactant: Emulgen 109P (2%), manufactured by Kao Corporation)
-Ammonium carbonate added so that the pH of the basic solution is 7.3

[Example 2]
As described in Table 1, Example 1 was prepared except that ammonium carbonate was added so that the pH of the basic solution to be applied before decreasing rate drying was 8.3 in Example 1. In the same manner, an ink jet recording medium was produced.

[Example 3]
An ink jet recording medium was prepared in the same manner as in Example 1 except that ammonium carbonate was added so that the pH of the basic solution was 7.8 in Example 1 to prepare a basic solution as shown in Table 1. Was made.

[Example 4]
In Example 1, ammonium carbonate was added so that the pH of the basic solution applied before the rate-reduction drying was 7.8, and the pH of the basic solution applied after the rate-reduction drying was 8.2. As shown in Table 1, an ink jet recording medium was produced in the same manner as in Example 1 except that ammonium carbonate was added to prepare a basic solution.

[Example 5]
As described in Table 1, except that ammonium carbonate added to the basic solution in Example 4 was changed to polyallylamine (PAA-10C, manufactured by Nittobo Co., Ltd., weight average molecular weight 15000) to prepare a basic solution. As described above, an ink jet recording medium was produced in the same manner as in Example 4.

[Example 6]
An ink jet recording medium was prepared in the same manner as in Example 4 except that the basic solution was prepared by changing the ammonium carbonate added to the basic solution to ammonia in Example 4, as shown in Table 1.

[Example 7]
An ink jet recording medium was prepared in the same manner as in Example 4 except that the basic solution was prepared by changing the ammonium carbonate added to the basic solution to NaOH in Example 4, as shown in Table 1.

[Example 8]
In Example 4, except that the basic solution was prepared by changing ammonium carbonate added to the basic solution to dimethylamine (using 50% aqueous solution), as described in Table 1, the same as in Example 4 was performed. An ink jet recording medium was produced.

[Example 9]
An ink jet recording medium was prepared in the same manner as in Example 4 except that the basic solution was prepared by changing the ammonium carbonate added to the basic solution to triethylamine in Example 4.

[Comparative Example 1]
InkJet recording medium as described in Example 1, except that ammonium carbonate was added so that the pH of the basic solution was 6.9 in Example 1 to prepare a basic solution as shown in Table 1. Was made.

[Comparative Example 2]
In Example 1, the basic solution was prepared as described in Table 1 except that ammonium carbonate was added so that the pH of the basic solution to be applied before drying at a reduced rate was 6.9. In the same manner, an ink jet recording medium was produced.

[Comparative Example 3]
In Example 1, except that ammonium carbonate was added to prepare a basic solution so that the pH of the basic solution to be applied after the rate-decreasing drying was 6.9, as shown in Table 1, Example 1 and In the same manner, an ink jet recording medium was produced.

[Comparative Example 4]
In Example 1, an ink jet recording medium was prepared in the same manner as in Example 1 except that the basic solution was not applied after drying at a reduced rate, as shown in Table 1.

[Comparative Example 5]
Comparative Example 4 was as shown in Table 1 except that ammonium carbonate was added to prepare a basic solution so that the pH of the basic solution to be applied before decreasing rate drying was 8.5 in Comparative Example 4. In the same manner, an ink jet recording medium was produced.

[Comparative Example 6]
In Example 1, an ink jet recording medium was produced in the same manner as in Example 1 as described in Table 1 except that the basic solution was not applied before the reduction rate drying.

[Comparative Example 7]
In Comparative Example 6, Example 1 was prepared as shown in Table 1 except that ammonium carbonate was added to prepare a basic solution so that the pH of the basic solution to be applied before decreasing rate drying was 8.5. In the same manner, an ink jet recording medium was produced.

[Comparative Example 8]
As described in Table 1, Example 1 except that ammonium carbonate was added so that the pH of the basic solution to be applied before decreasing rate drying was 8.7. In the same manner, an ink jet recording medium was produced.

[Performance evaluation]
The ink jet recording medium obtained above was evaluated as follows.

<Scratch resistance>
Each inkjet recording medium was cut into A4 size. Two sheets of the inkjet recording medium cut into the A4 size were superposed on a horizontal and flat test table. At this time, each ink jet recording medium is overlaid so that the ink receiving layer surface of the lower ink jet recording medium and the back surface of the upper ink jet recording medium are in contact with each other. While applying a load of 500 g / A4 size from above the upper upper inkjet recording medium, the lower inkjet recording medium was pulled out at a speed of 1 cm / second, and was formed on the surface of the ink receiving layer of the lower inkjet recording medium. The wound was evaluated according to the following criteria.
〔Evaluation criteria〕
A: No scratches are observed A: Slight scratches are observed B: Scratches are observed, but there are no practical problems C: Scratches are a problem

<Brittleness>
The inkjet recording medium was stored in a constant temperature and humidity chamber at 10 ° C. and a relative humidity of 20% for 1 day, and then wound around a cylinder (diameter 10 mm, 20 mm, 30 mm, 40 mm) to evaluate brittleness. The smaller the diameter of the cylinder, the more easily the ink receiving layer cracks, and the diameter of the cylinder at which cracking occurs is taken as the brittle value.

<Surface shape>
Whether or not cracking occurred in an arbitrary 40 m ² of the inkjet recording medium after the drying step was visually observed and evaluated according to the following evaluation criteria.
〔Evaluation criteria〕
A: No occurrence of cracks A: Slight occurrence of cracks B: Generation of cracks, but no problem in practical use C: Level of occurrence of cracks in practical use

<Burning wet heat>
Using an inkjet printer (Seiko Epson Corp .; PM-900C), a grid-like linear pattern (line width 0.28 mm) in which magenta ink and black ink were adjacent to each other was printed on each inkjet recording medium. . Immediately after printing, the printed inkjet recording medium was inserted into a transparent PP file, and stored for 3 days in an environment of 35 ° C. and a relative humidity of 80%. Thereafter, the width of the black line of the linear pattern was visually observed with an optical microscope.
〔Evaluation criteria〕
A: No occurrence of bleeding is observed A: Generation of slight bleeding is observed B: Generation of bleeding is observed, but there is no practical problem C: Generation of bleeding becomes a problem

  As is clear from Table 1, the examples satisfying the constitutional requirements of the present invention were good in any evaluation items. On the other hand, it was found that the comparative example was inferior in at least one of abrasion resistance and brittleness.

Claims (4)

A step of cross-linking and curing an application layer formed by applying a first liquid containing inorganic fine particles, a water-soluble resin, and a boron compound on a support to form an ink receiving layer, (1) At the same time that the first liquid is applied, or (2) either during the drying of the coating layer formed by applying the first liquid and before the coating layer exhibits reduced-rate drying. At this time, a second liquid having a pH of 7.1 to 8.5 is applied, dried, and further, after the coating layer formed by applying the second liquid is subjected to the rate-decreasing drying, the second liquid having a pH of 7.1 or higher is applied. 3. A method for producing an ink jet recording medium, which is performed by applying the liquid (3). The method for producing an ink jet recording medium according to claim 1, wherein the pH of the third liquid is 8.0 or more. The second liquid or the third liquid contains a basic substance, and the basic substance is at least one selected from ammonia, a primary amine, a secondary amine, and a tertiary amine. The method for producing an ink jet recording medium according to claim 1, wherein: The inkjet recording medium manufactured with the manufacturing method of any one of Claims 1-3.