JP2010076227A - Inkjet recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording medium on which images of a higher image concentration can be recorded. <P>SOLUTION: The inkjet recording medium includes: an intermediate layer containing a water-soluble polymeric plasticizer of a particle weight 800 or higher such as a polyglycerin, a diglyceril ether, a polyethylene glycol, and a copolymer of the polyethylene glycol and a polypropylene glycol selected from polyhydric alcohols and their ethers; and an ink accepting layer containing an inorganic particle and a water-soluble resin on a supporting body in this order from the supporting body side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ink jet recording medium having an ink receiving layer for receiving ink.

  In recent years, various methods have been proposed as an image recording method for recording an image. In any case, there is a high demand for the quality of recorded matter, such as image quality. For example, as an ink jet recording method, a method using an ink jet recording medium in which a recording layer that receives ink has a porous structure has been put into practical use.

  As an example, an ink jet recording medium has been proposed in which a recording layer containing inorganic pigment particles and a water-soluble binder and having a high porosity is provided on a support. Since this has a porous structure, it is excellent in the quick-drying property of the ink. Thus, while high ink absorptivity is important as one of the recording characteristics, there is a tendency that the image density tends to decrease, and a recorded image with higher density and higher image quality than before can be obtained. Various recording media for ink-jet recording have been studied, but sufficient performance has not necessarily been obtained.

  As a technique related to ink jet recording, for example, an ink jet recording medium having an ink receiving layer containing a water-soluble organic solvent of 7% by mass or more and less than 20% by mass with respect to inorganic fine particles is disclosed (for example, see Patent Document 1). It is said that the ink absorbability is excellent by adding a water-soluble organic solvent to the ink receiving layer.

In addition, an ink jet recording paper is disclosed in which a layer containing a water-soluble plasticizer together with inorganic fine particles, an emulsion and a mordant, and an ink absorbing layer containing inorganic fine particles and the like are sequentially provided (see, for example, Patent Document 2). It is said that the curling resistance can be improved by adding a plasticizer to the lower layer of the ink receiving layer.
JP 2007-98657 A JP 2003-312122 A

  However, in the above-described ink jet recording medium in which the ink receiving layer contains a water-soluble organic solvent, the print density is lowered as the ink absorbability is improved, and performance such as sufficient density cannot be obtained.

  Further, even with the above-described ink jet recording paper in which a water-soluble plasticizer is added to the lower layer of the ink receiving layer, it is not always possible to obtain performance such as a sufficient concentration.

  The present invention has been made in view of the above, and an object of the present invention is to provide an ink jet recording medium capable of recording an image having a higher image density than the conventional one, and to achieve the object.

Specific means for achieving the above object are as follows.
<1> An inkjet having, on the support, in order from the support side, an intermediate layer containing a water-soluble polymer plasticizer having a molecular weight of 800 or more and a water-soluble resin, and an ink receiving layer containing inorganic fine particles and a water-soluble resin. It is a recording medium.

  <2> The inkjet recording medium according to <1>, wherein the polymer plasticizer is at least one selected from polyhydric alcohols and ethers thereof.

  <3> The <1> or <2 above, wherein the polymer plasticizer is at least one of polyglycerin, diglyceryl ether, polyethylene glycol, and a copolymer of polyethylene glycol and polypropylene glycol. > Is an ink jet recording medium.

  <4> The inkjet recording medium according to any one of <1> to <3>, wherein the intermediate layer further contains inorganic fine particles.

  According to the present invention, it is possible to provide an ink jet recording medium capable of recording an image having a higher image density than in the past.

Hereinafter, the ink jet recording medium of the present invention will be described in detail.
The inkjet recording medium of the present invention comprises a support, an intermediate layer containing a water-soluble polymer plasticizer having a molecular weight of 800 or more and a water-soluble resin, inorganic fine particles, and a water-soluble resin on the support in this order from the support side. And an ink receiving layer.

  In the present invention, a polymer plasticizer having a relatively low molecular weight is contained in a lower layer of an ink receiving layer that receives ink (a layer provided between the ink receiving layer and the support; the same applies hereinafter), It is possible to record an image having a higher image density than the above. Further, the inclusion of the polymer plasticizer makes the ink solvent absorbability in the lower layer good, and the effect of improving the ink absorption capacity is obtained, and the brittleness is improved.

-Intermediate layer-
The ink jet recording medium of the present invention has an intermediate layer containing a water-soluble polymer plasticizer having a molecular weight of 800 or more and a water-soluble resin between the ink receiving layer and the support. An intermediate | middle layer can be comprised using other components, such as an inorganic fine particle and surfactant, as needed.

(Polymer plasticizer)
The intermediate layer in the present invention contains at least one kind of water-soluble polymer plasticizer. The polymer plasticizer itself is a polymer that is miscible with the water-soluble resin and has a plasticizing effect. Moreover, water-soluble means that 1 mass% or more melt | dissolves with respect to 25 degreeC pure water.

  As content in the intermediate | middle layer of a polymeric plasticizer, 10-300 mass% is preferable with respect to the water-soluble resin in a layer, 20-250 mass% is more preferable, 25-200 mass% is further more preferable, 30-180 mass% is especially preferable. By setting the content of the water-soluble polymer plasticizer in the above range, an image having a higher density than the conventional one can be obtained without causing the adverse effect of decreasing the water resistance. Further, the ink solvent absorbability in the intermediate layer is improved, and an ink jet recording medium excellent in ink absorption capacity and brittleness can be obtained.

  As the water-soluble polymer plasticizer, for example, polyhydric alcohols and ethers thereof are preferable. Specific examples include glycol compounds, among which polyglycerin, diglyceryl ether, polyethylene glycol, and a copolymer of polyethylene glycol and polypropylene glycol are preferable. More preferred are polyglycerin and polyethylene glycol in terms of the effect of improving the image density. Further, it is also preferable from the viewpoint of improving the ink absorption capacity and the brittleness of the inkjet recording medium.

  The molecular weight of the water-soluble polymer plasticizer is 800 or more. When the molecular weight is less than 800, the image density decreases. Further, when the intermediate layer and the ink receiving layer described later are formed by simultaneous multilayers, the polymer plasticizer in the liquid for forming the intermediate layer easily moves to the adjacent liquid for forming the ink receiving layer, and the image density Decreases. Especially, 1000-20000 are preferable, as for molecular weight, 2500-20000 are more preferable, 5000-20000 are especially preferable, 5000-15000 are the most preferable. By setting the molecular weight of the polymer plasticizer within the above range, an ink jet recording medium having high image density and ink absorption capacity and low brittleness can be obtained. In particular, when the molecular weight is 20000 or less, the plasticizing effect by the polymer plasticizer is large.

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

  Among these, polyvinyl alcohol is preferable from the viewpoint of further improving the image density when used in combination with the polymer plasticizer. Moreover, polyvinyl alcohol and said other water-soluble resin can also be used together. When used in combination, the amount of polyvinyl alcohol relative to the total mass of the water-soluble resin is preferably 90% by mass or more, and more preferably 95% by mass or more.

  In addition to polyvinyl alcohol (PVA), the polyvinyl alcohol includes cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, silanol-modified polyvinyl alcohol, and other polyvinyl alcohol derivatives. Polyvinyl alcohol can be used alone or in combination of two or more.

  As a number average polymerization degree of the said polyvinyl alcohol (PVA), 1800 or more are preferable from a viewpoint of crack prevention, and 2000 or more are more preferable. Further, from the viewpoint of transparency and the viscosity of a preparation liquid (for example, a coating liquid) for forming an intermediate layer, PVA having a saponification degree of 88% or more is preferable, and PVA having a saponification degree of 95% or more is particularly preferable.

  The content of the water-soluble resin (especially polyvinyl alcohol) in the intermediate layer is to prevent a decrease in film strength due to an insufficient amount and cracking during drying, and in the layer due to an excessive amount when inorganic fine particles described later are included. From the viewpoint of preventing the ink absorbability from being lowered due to the void ratio being easily blocked by the resin, and 9% of the total solid mass of the layer when the intermediate layer is formed. -40 mass% is preferable and 12-33 mass% is more preferable.

  The intermediate layer in the present invention is made of polyglycerin, diglyceryl ether, polyethylene glycol, and a copolymer of polyethylene glycol and polypropylene glycol from the viewpoint of obtaining high image density and further improving ink absorption capacity and brittleness. The case where 1 type, 2 or more types, and polyvinyl alcohol are contained is preferable.

  As the content ratio (x / y) of the polymer plasticizer (x) and the water-soluble resin (especially polyvinyl alcohol; y) in the intermediate layer, a high image density is obtained, and further, the ink absorption capacity and brittleness are obtained. Is preferably from 0.1 to 3.0, more preferably from 0.2 to 2.5, further preferably from 0.25 to 2.0, particularly preferably from 0.3 to 1.8% by mass. preferable.

(Inorganic fine particles)
The intermediate layer in the present invention can contain at least one kind of inorganic fine particles. By containing inorganic fine particles, an ink receptive layer having a porous structure such as the following ink receptive layer can be formed.

  As the inorganic fine particles, the same inorganic fine particles that can be used in the following ink receiving layer can be used, and are selected from silica particles, colloidal silica, alumina fine particles, and pseudoboehmite from the viewpoint of forming a good porous structure. At least one selected from the above is preferred.

  Details and preferred embodiments of the inorganic fine particles will be described in detail in the section of the ink receiving layer below.

  When polyvinyl alcohol (PVA) is used as the water-soluble resin, PVA has a hydroxyl group in its structural unit, and this hydroxyl group easily forms hydrogen bonds with silanol groups on the surface of the silica particles when, for example, silica particles are used in combination. Therefore, it is possible to form a three-dimensional network structure in which the secondary particles of silica particles are chain units. It is considered that the intermediate layer can be formed into a porous layer having a high porosity by forming a three-dimensional network structure.

  The content of the inorganic fine particles in the intermediate layer is preferably 1.5 parts by mass to 10 parts by mass with respect to 1 part by mass of the water-soluble resin.

(Other ingredients)
The intermediate layer in the present invention can be further constituted using components such as a crosslinking agent, a mordant, a surfactant, and other additives that crosslink the water-soluble resin. The details of the crosslinking agent, mordant, surfactant, and other additives are the same as those in the ink receiving layer described later, and the preferred embodiments are also the same.

-Ink receiving layer-
The ink jet recording medium of the present invention has an ink receiving layer containing inorganic fine particles and a water-soluble resin on the intermediate layer. The ink receiving layer can be constituted by using components such as a water-soluble resin crosslinking agent, a surfactant, and a mordant as required. The ink receiving layer receives ink applied from the outside and records an image.

  The ink-receiving layer laminated on the intermediate layer may contain the water-soluble polymer plasticizer, but the content of the polymer plasticizer is preferably small, and the ink-receiving layer has a high content. As content of a molecular plasticizer, it is preferable that it is 50 mass% or less with respect to water-soluble resin. When the content of the polymer plasticizer in the ink-receiving layer is 50% by mass or less, a higher image density can be obtained than in the past.

(Inorganic fine particles)
The ink receiving layer in the present invention contains at least one kind of inorganic fine particles.
Examples of the inorganic fine particles include silica particles, colloidal silica, titanium dioxide, barium sulfate, calcium silicate, zeolite, kaolinite, halloysite, mica, talc, calcium carbonate, magnesium carbonate, calcium sulfate, pseudoboehmite, zinc oxide, and hydroxide. Examples include zinc, alumina fine particles, aluminum silicate, calcium silicate, magnesium silicate, zirconium oxide, zirconium hydroxide, cerium oxide, lanthanum oxide, and yttrium oxide. Among these, from the viewpoint of forming a good porous structure, at least one selected from silica particles, colloidal silica, alumina fine particles, and pseudoboehmite is preferable. The fine particles may be used as primary particles or in a state where secondary particles are formed. The average primary particle size of these fine particles is preferably 2 μm or less, and more preferably 200 nm or less.
Furthermore, silica particles having an average primary particle size of 20 nm or less, colloidal silica having an average primary particle size of 30 nm or less, alumina fine particles having an average primary particle size of 20 nm or less, or pseudoboehmite having an average pore radius of 2 to 15 nm is more preferable. .

  Silica particles are generally roughly classified into wet method (precipitation method) particles and dry method (vapor phase method) particles according to the production method. In the above precipitation method, active silica is produced by acid decomposition of silicate, and this is a method in which this is appropriately polymerized and agglomerated and precipitated to obtain hydrous silica. “Precipitated silica” is obtained by the precipitation method. It means the obtained hydrous silica particles. 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 “gas phase method silica” means anhydrous silica particles obtained by the gas phase method. As the silica particles used in the present invention, gas phase method silica fine particles are particularly preferable.

The gas phase method silica is different from hydrous silica in terms of the density of silanol groups on the surface, the presence or absence of vacancies, etc., and exhibits different properties, but is suitable for forming a three-dimensional structure with a high porosity. The reason for this is not clear, but in the case of hydrous silica, the density of the silanol groups on the surface of the fine particles is high at 5 to 8 / nm ² , and the silica particles tend to agglomerate (aggregate) easily. 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 agglomeration (flocculate), resulting in a structure with a high porosity. Is done.

  Silica particles including gas phase method silica have a particularly large specific surface area, and can be formed into a porous structure when, for example, an ink receiving layer is formed. By dispersing to an appropriate particle size, transparency can be imparted 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.

  In particular, silica particles have a silanol group on the surface, and the particles are likely to adhere to each other by hydrogen bonding due to the silanol group, and also because the particles adhere to each other via the silanol group and a water-soluble resin. In addition, when the average primary particle diameter is 10 nm or less, a high porosity and a highly transparent structure can be formed, and ink absorption characteristics can be effectively improved.

Pseudoboehmite is represented by Al ₂ O ₃ .xH ₂ O (1 <x <2). In general, the crystal is a layered compound in which a (020) plane forms a huge plane, and its lattice constant d is 0. .67 nm. Here, the pseudo boehmite has a structure containing excess water between (020) plane layers. Pseudoboehmite absorbs ink well and can fix it, and can improve the absorptivity and bleeding of ink over time. In addition, since a smooth layer can be easily obtained, it is preferable to use sol-like pseudoboehmite (pseudoboehmite sol) as a raw material.

  Furthermore, the aspect ratio of the pseudo boehmite is preferably 3 to 10. About the pore structure of pseudo boehmite, the average pore radius is preferably 1 to 30 nm, and more preferably 2 to 15 nm. The pore volume is preferably 0.3 to 2.0 ml / g (cc / g), more preferably 0.5 to 1.5 ml / g (cc / g). Here, the pore radius and pore volume are measured by a nitrogen adsorption / desorption method, and can be measured by, for example, a gas adsorption / desorption analyzer (for example, trade name “Omni Soap 369” manufactured by Coulter). .

The inorganic fine particles preferably have a specific surface area of 250 m ² / g or more by the BET method. When the specific surface area according to the BET method is a small particle size of 250 m ² / g or more, the particle surface area becomes large. Therefore, when the ink receiving layer is formed, the ink absorbency is improved, quick drying and prevention of ink bleeding are achieved. The image quality can be increased to form a high-quality image, which is advantageous in terms of increasing the print density.
The BET specific surface area of pseudo boehmite is preferably 250 to 500 m ² .

  The BET method is one of the methods for measuring the surface area of a powder by a vapor phase adsorption method, and is a method for obtaining the total surface area, that is, the specific surface area of a 1 g sample from an adsorption isotherm. Usually, nitrogen gas is used as the adsorbed gas, and a method of measuring the amount of adsorption from the change in pressure or volume of the gas to be adsorbed is common. A prominent expression of the isotherm of multimolecular adsorption is the Brunauer Emmett and Teller equation (BET equation). Based on this, the amount of adsorption is obtained, and the surface area is obtained by multiplying the area occupied by one adsorbed molecule on the surface. .

  The content of the inorganic fine particles in the ink receiving layer is preferably 5 to 25% by mass and more preferably 8 to 20% by mass with respect to the mass of the ink receiving layer.

(Water-soluble resin)
The ink receiving layer in the invention contains at least one water-soluble resin. As the water-soluble resin, the same water-soluble resins that can be used in the intermediate layer can be used, and among them, polyvinyl alcohol is preferable. Moreover, polyvinyl alcohol and said other water-soluble resin can also be used together. The amount of polyvinyl alcohol in the total mass of the water-soluble resin when used in combination is preferably 90% by mass or more, and more preferably 95% by mass or more.
The details of the water-soluble resin (including polyvinyl alcohol) are as described above.

  When silica is used as the inorganic fine particles, polyvinyl alcohol (PVA) has a hydroxyl group in its structural unit, and this hydroxyl group easily forms a hydrogen bond with a silanol group on the surface of the silica particle. A three-dimensional network structure having particles as chain units is easily formed. By forming this three-dimensional network structure, it is considered that an ink receiving layer having a porous structure with a high porosity is formed. The ink receiving layer having a porous structure as described above can absorb ink rapidly by capillary action during ink jet recording, and can form dots with good roundness without ink bleeding.

  The content of the water-soluble resin (especially polyvinyl alcohol) in the ink receiving layer is to prevent the film strength from being reduced due to the insufficient amount and cracking at the time of drying, and the excessive amount makes it easy for the voids to be blocked by the resin. From the viewpoint of preventing the ink absorbency from being lowered due to a decrease in the porosity, the amount is preferably 9 to 40% by mass, and preferably 12 to 33%, based on the total solid content of the ink receiving layer. The mass% is more preferable.

  The number average degree of polymerization of polyvinyl alcohol (PVA) is preferably 1800 or more, more preferably 2000 or more, from the viewpoint of preventing cracks. From the viewpoint of transparency and the viscosity of the coating liquid for forming the ink receiving layer, PVA having a saponification degree of 88% or more is preferable, and PVA having a saponification degree of 95% or more is particularly preferable.

-Content ratio of inorganic fine particles and water-soluble resin-
The content ratio of the inorganic fine particles (i) to the water-soluble resin (p) [PB ratio (i: p); the mass of the inorganic fine particles relative to 1 part by mass of the water-soluble resin] has a great influence on the film structure when the layer is formed. give. That is, as the PB ratio increases, the porosity, pore volume, and surface area (per unit mass) increase. Specifically, as the PB ratio, it is possible to prevent a decrease in film strength due to the PB ratio being too large and cracking at the time of drying, and the PB ratio is too small so that the voids are easily blocked by the resin. From the viewpoint of preventing the ink absorbency from being lowered due to the decrease in the porosity, 1.5: 1 to 10: 1 is preferable.

Since stress may be applied when the ink jet recording medium passes 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 cracking or peeling of the ink receiving layer. From this viewpoint, 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 a vapor phase silica having an average primary particle size 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 applied on a support, and the coating layer Is dried, a three-dimensional network structure is formed in which the secondary particles of silica particles are chain units, and a light-transmitting porous film can be easily formed.

(Other ingredients)
The ink receiving layer in the invention can contain various components such as a crosslinking agent, a mordant, and a surfactant in addition to the above components.

~ Crosslinking agent ~
The ink receiving layer can contain at least one crosslinking agent that crosslinks the water-soluble resin. By including a crosslinking agent, a porous layer cured by a crosslinking reaction between the crosslinking agent and the water-soluble resin can be formed.

Boron compounds are preferred for crosslinking the above water-soluble resins, particularly polyvinyl alcohol resins. 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 ), etc. Of these, borax, boric acid, and borate are preferable, and boric acid is particularly preferable in that a crosslinking reaction can be promptly caused.

  Moreover, the following compounds other than a boron compound can also be used. For example, aldehyde compounds such as formaldehyde, glyoxal and glutaraldehyde; ketone compounds such as diacetyl and cyclopentanedione; bis (2-chloroethylurea) -2-hydroxy-4,6-dichloro-1,3,5- Active halogen compounds such as triazine and 2,4-dichloro-6-S-triazine sodium salt; divinylsulfonic acid, 1,3-vinylsulfonyl-2-propanol, N, N′-ethylenebis (vinylsulfonylacetamide) ), Active vinyl compounds such as 1,3,5-triacryloyl-hexahydro-S-triazine; N-methylol compounds such as dimethylolurea and methyloldimethylhydantoin; melamine resins (for example, methylolmelamine, alkylated methylolmelamine) Epoxy resin; 1,6- Isocyanate compounds such as hexamethylene diisocyanate; Aziridine compounds described in US Pat. Nos. 3,017,280 and 2,983611; Carboximide compounds described in US Pat. No. 3,100,704; Epoxys such as glycerol triglycidyl ether Compounds; ethyleneimino compounds such as 1,6-hexamethylene-N, N′-bisethyleneurea; halogenated carboxaldehyde compounds such as mucochloric acid and mucophenoxycyclolic acid; dioxane such as 2,3-dihydroxydioxane Compounds: titanium lactate, aluminum sulfate, chromium alum, potash alum, metal-containing compounds such as zirconyl acetate and chromium acetate, polyamine compounds such as tetraethylenepentamine, hydrazide compounds such as adipic acid dihydrazide, oxazo A low molecule or polymer containing two or more phosphorus groups. The above crosslinking agents may be used alone or in combination of two or more.

  The crosslinking agent may be added to the ink receiving layer coating liquid and / or the coating liquid for forming an adjacent layer of the ink receiving layer when the ink receiving layer coating liquid is applied, or may be previously crosslinked. The coating solution for the ink receiving layer is coated on the support on which the coating solution containing the coating agent is coated. The coating solution for the ink receiving layer containing or not containing the crosslinking agent is coated and dried, and then the basic solution is overcoated. For example, the crosslinking agent can be supplied to the ink receiving layer.

  For example, the crosslinking agent can be suitably applied as follows. Here, a boron compound will be described as an example. That is, for example, when the ink receiving layer is a layer obtained by crosslinking and curing the coating layer coated with the ink receiving layer coating liquid (coating liquid A), the crosslinking curing is performed by (1) applying the coating liquid A to the coating layer. (2) During the dry coating of the coating layer formed by coating the coating liquid A and before the coating layer exhibits reduced-rate drying, the basic solution is It is carried out by applying to the coating layer. At this time, the boron compound as a crosslinking agent may be contained in either the coating solution A or the basic solution, and may be contained in both of these solutions. When the ink receiving layer is composed of two or more layers, two or more coating liquids can be applied in multiple layers, and a basic solution may be applied from the layer formed.

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

~ Surfactant ~
A surfactant can be used in the ink receiving layer (or the preparation liquid for forming the ink receiving layer). As the surfactant, any of cationic, anionic, nonionic, amphoteric, fluorine and silicone surfactants can be used. These surfactants may be used alone or in combination of two or more.

  Examples of the nonionic surfactant include polyoxyalkylene alkyl ethers and polyoxyalkylene alkyl phenyl ethers (for example, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyalkylene ether) 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 sorbitant Oleate, etc.), polyoxyethylene sorbitol fatty acid esters (eg, polyoxyethylene sorbitol tetraoleate), glycerin fatty acid esters (eg, glycerol monooleate), polyoxyethylene glycerin fatty acid esters (polyoxymonostearate) Ethylene glycerol, monooleic acid polyoxyethylene glycerin, etc.), polyoxyethylene fatty acid esters (polyethylene glycol monolaurate, polyethylene glycol monooleate, etc.), polyoxyethylene alkylamine, acetylene glycols (eg, 2, 4, 7) , 9-tetramethyl-5-decyne-4,7-diol, and ethylene oxide adducts and propylene oxide adducts of the diols), and the like. Sharp emission alkyl ethers are preferable. The nonionic surfactant may be contained in the ink receiving layer coating solution.

  Examples of the amphoteric surfactant include amino acid type, carboxyammonium betaine type, sulfoammonium betaine type, ammonium sulfate betaine type, imidazolium betaine type, and the like, for example, US 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.

Examples of the anionic surfactant include fatty acid salts (for example, sodium stearate, potassium oleate), alkyl sulfate esters (for example, sodium lauryl sulfate, triethanolamine lauryl sulfate), and sulfonates (for example, sodium dodecylbenzenesulfonate). Alkyl sulfosuccinate (for example, sodium dioctyl sulfosuccinate), alkyl diphenyl ether disulfonate, alkyl phosphate, and the like.
Examples of the cationic surfactant include alkylamine salts, quaternary ammonium salts, pyridinium salts, imidazolium salts, and the like.

  Examples of the fluorosurfactant include compounds derived via an intermediate having a perfluoroalkyl group using a method such as electrolytic fluorination, telomerization, or oligomerization. Examples thereof include perfluoroalkyl sulfonates, perfluoroalkyl carboxylates, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl trialkyl ammonium salts, perfluoroalkyl group-containing oligomers, and perfluoroalkyl phosphate esters.

  The silicone surfactant is preferably a silicone oil modified with an organic group, and can have a structure in which a side chain of a siloxane structure is modified with an organic group, a structure in which both ends are modified, or a structure in which one end is modified. Examples of the organic group modification include amino modification, polyether modification, epoxy modification, carboxyl modification, carbinol modification, alkyl modification, aralkyl modification, phenol modification, and fluorine modification.

  The content of the surfactant in the ink receiving layer coating solution is preferably 0.001 to 2.0%, more preferably 0.01 to 1.0%.

~mordant~
The ink receiving layer can contain a mordant for the purpose of further improving the bleeding and water resistance of the image.
Examples of mordants include organic mordants such as cationic polymers (cationic mordants), and inorganic mordants such as water-soluble metal compounds. The cationic mordant is preferably a polymer mordant having a primary to tertiary amino group or a quaternary ammonium base as a cationic functional group, but a cationic non-polymer mordant can also be used.

  As the polymer mordant, a homopolymer of a monomer having a primary to tertiary amino group and a salt thereof, or a quaternary ammonium base (a mordant monomer), or the mordant monomer and other monomers (non-mordant) Those obtained as copolymers or condensation polymers with mordant monomers) are preferred. Moreover, these polymer mordants can be used in any form of a water-soluble polymer or water-dispersible latex particles.

Examples of the 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-Np-vinylbenzyl Ammonium chloride, N, N-dimethyl-Nn-octyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N-benzyl-Np-vinylbenzylammonium chloride, N, N-diethyl-N Benzyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N- (4-methyl) benzyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-N-phenyl-Np-vinyl Benzylammonium 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 with their anions.

Specific examples of the compound include monomethyl diallylammonium 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- (acryloylua) C) ethylammonium 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.
In addition, a polymerization unit such as N-vinylacetamide, N-vinylformamide or the like, which is converted into a vinylamine unit by hydrolysis after polymerization, and a salt thereof can be used.

  The non-mordant monomer 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 a monomer having a substantially small interaction. For example, (meth) acrylic acid alkyl ester; (meth) acrylic acid cycloalkyl ester such as cyclohexyl (meth) acrylic acid; (meth) acrylic acid aryl ester such as phenyl (meth) acrylate; benzyl (meth) acrylic acid Aralkyl esters of styrene; vinyl aromatics such as styrene, vinyl toluene and α-methyl styrene; vinyl esters such as vinyl acetate, vinyl propionate and vinyl versatate; allyl esters such as allyl acetate; vinylidene chloride, vinyl chloride, etc. Halogen-containing monomers, vinyl cyanides such as (meth) acrylonitrile, olefins such as ethylene and propylene, and the like.

  The (meth) acrylic acid alkyl ester is preferably a (meth) acrylic acid alkyl ester having 1 to 18 carbon atoms in the alkyl moiety, specifically, for example, methyl (meth) acrylate or ethyl (meth) acrylate. Propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, (meth) Examples include octyl acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and the like. Among these, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and hydroxyethyl methacrylate are preferable. The non-mordant monomer can also be used alone or in combination of two or more.

  Further, as the polymer mordant, polydiallyldimethylammonium chloride, polymethacryloyloxyethyl-β-hydroxyethyldimethylammonium chloride, polyethyleneimine, polyallylamine and a modified product thereof, polyallylamine hydrochloride, polyamide-polyamine resin, cationized starch, Dicyandiamide formalin condensate, dimethyl-2-hydroxypropylammonium salt polymer, polyamidine, polyvinylamine, cationic polyurethane resin described in JP-A-10-86505, and the like are also preferred.

  The modified polyallylamine is obtained by adding 2 to 50 mol% of acrylonitrile, chloromethylstyrene, TEMPO, epoxy hexane, sorbic acid or the like to polyallylamine, 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 an 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 above range, water resistance and aging resistance can be improved.

-Water-soluble polyvalent metal compound-
The ink receiving layer preferably contains a water-soluble polyvalent metal compound as a dispersant for the inorganic fine particles.
The water-soluble polyvalent metal compound is desirably contained in the following range. That is, the content of the water-soluble polyvalent metal compound in the ink receiving layer is preferably 20 to 40% by mass with respect to the inorganic fine particles. When the content is within this range, when preparing a preparation liquid for forming an ink receiving layer, a dispersion liquid having a zeta potential ζ in the dispersion stable potential region of 60 mV or more can be prepared. On the other hand, when the content is 20% by mass or more, the dispersion state can be maintained well while maintaining the zeta potential ζ of the dispersion, and when the content is 40% by mass or less without causing other harmful effects. An ink receiving layer having high whiteness can be obtained.

  Examples of the water-soluble polyvalent metal compound include water-soluble salts of metals selected from calcium, barium, manganese, copper, cobalt, nickel, aluminum, iron, zinc, zirconium, chromium, magnesium, tungsten, and molybdenum. Specific examples include calcium acetate, calcium chloride, calcium formate, calcium sulfate, calcium butyrate, barium acetate, barium sulfate, barium phosphate, barium oxalate, barium naphthoresorcin carboxylate, barium butyrate, manganese chloride, manganese acetate, formic acid Manganese dihydrate, manganese ammonium sulfate hexahydrate, cupric chloride, ammonium copper (II) chloride dihydrate, copper sulfate, copper (II) butyrate, copper oxalate, copper phthalate, copper citrate , Copper gluconate, naphthenic copper, cobalt chloride, cobalt thiocyanate, cobalt sulfate, cobalt (II) acetate, cobalt naphthenate, nickel sulfate hexahydrate, nickel chloride hexahydrate, nickel acetate tetrahydrate, sulfuric acid Nickel ammonium hexahydrate, nickel amidosulfate tetrahydrate, nickel sulfamate, 2- Nickel tilhexanoate, aluminum sulfate, aluminum sulfite, aluminum thiosulfate, polyaluminum chloride, aluminum nitrate nonahydrate, aluminum chloride hexahydrate, aluminum acetate, aluminum lactate, basic aluminum thioglycolate, ferrous bromide , Ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, iron (III) citrate, iron (III) lactate trihydrate, triammonium iron oxalate (III) trihydrate , Zinc bromide, zinc chloride, zinc nitrate hexahydrate, zinc sulfate, zinc acetate, zinc lactate, zirconium acetate, zirconium chloride, zirconium chloride octahydrate, zirconium zirconium chloride, chromium acetate, chromium sulfate, acetic acid Magnesium, magnesium oxalate, magnesium sulfate, magnesium chloride hexahydrate, magnesium citrate Dihydrate, sodium phosphate, sodium tungsten citrate, 12 tungstophosphoric acid n-hydrate, dodecatungstosilicic acid 26-hydrate, molybdenum chloride, dodecamolybdophosphoric acid n-hydrate, and the like. These water-soluble polyvalent metal compounds may be used alone or in combination of two or more.

  Further, “water-soluble” in the water-soluble polyvalent metal compound means that 1% by mass or more is dissolved in 20 ° C. water.

  Among the water-soluble polyvalent metal compounds, compounds containing aluminum or a metal element of group 4A (group 18 long-period table 4) of the periodic table (for example, zirconium or titanium) are preferable. Particularly preferred is a water-soluble aluminum compound. Examples of the water-soluble aluminum compound include, as inorganic salts, aluminum chloride or a hydrate thereof, aluminum sulfate or a hydrate thereof, ammonium alum and the like, and a basic polyaluminum hydroxide compound which is an inorganic aluminum-containing cationic polymer. Is preferable.

The basic polyaluminum hydroxide compound has a main component represented by the following general formula 1, 2 or 3,
_{[Al 2 (OH) n Cl} 6-n] m ... Formula 1
[Al (OH) ₃ ] _n AlCl ₃ ... General formula 2
Al _n (OH) _m Cl _(3n-m) [0 <m <3n] ... General formula 3
For example, [Al ₆ (OH) ₁₅ ] ³⁺ , [Al ₈ (OH) ₂₀ ] ⁴⁺ , [Al ₁₃ (OH) ₃₄ ] ⁵⁺ , [Al ₂₁ (OH) ₆₀ ] ³⁺ , etc. It is a water-soluble polyaluminum hydroxide that stably contains the polynuclear condensed ions.

  Moreover, as these commercial items, for example, polyaluminum chloride (PAC) manufactured by Taki Chemical Co., Ltd., water treatment agent PAC # 1000, Takibaine # 1500, Silojet A200 manufactured by Grace Japan Co., Ltd. Various grades can be readily obtained from RIKEN Green's HAP-25 and other commercial products provided for similar purposes.

  As a compound containing said periodic table 4A group element, the 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.

~ Other additives ~
Furthermore, the ink receiving layer may contain additives such as various ultraviolet absorbers, surfactants, antioxidants, and anti-fading agents such as singlet oxygen quenchers as necessary. The details of these additives can be referred to the descriptions in paragraphs [0081] to [0090] of JP-A-2007-98657.

-Support-
The inkjet recording medium of the present invention is configured using a support.
As the support, either a transparent support made of a transparent material such as plastic or an opaque support made of an opaque material such as paper can be used. In order to make use of the transparency of the ink receiving layer, it is preferable to use a transparent support or a highly glossy opaque support.

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 backlight display. Examples of such materials 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 the ease of handling.

  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 support such as art paper, coated paper, cast coated paper, baryta paper used for silver salt photographic support, etc .; polyesters such as polyethylene terephthalate (PET), nitrocellulose, cellulose acetate , Cellulose esters such as cellulose acetate butyrate, and plastic films such as polysulfone, polyphenylene oxide, polyimide, polycarbonate, and polyamide are made opaque by adding a white pigment or the like (surface calendering may be applied). Glossy film; or a support in which a polyolefin coating layer containing or not containing a white pigment is provided on the surface of a highly glossy film containing the various paper supports, the transparent support or the white pigment. Etc.
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 the ease of handling.
In addition, it is preferable to use a surface of the support that has been subjected to corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet irradiation treatment or the like in order to improve wettability and adhesion.

Next, a base paper used for a paper support such as resin-coated paper will be described.
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 wood pulp, any of LBKP, LBSP, NBKP, NBSP, LDP, NDP, LUKP, NUKP can be used, but it is preferable to use more LBKP, NBSP, LBSP, NDP, LDP with a lot of short fibers. preferable. However, the ratio of LBSP and / or LDP is preferably 10% by mass to 70% by mass.

As the above-mentioned pulp, chemical pulp (sulfate pulp or sulfite pulp) with few impurities is suitably used, and a pulp whose whiteness is improved by performing a bleaching treatment 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% and a 42 mesh residual as defined in JIS P-8207. 30 to 70% of the sum with the mass% of is preferable. The 4 mesh residue is preferably 20% by 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.

  In the case of a support on which the front and back surfaces of the base paper are coated, the polyethylene covering the base paper mainly includes low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but other LLDPE and polypropylene Etc. can also be used in part.

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

  Polyethylene-coated paper coated with a polyethylene layer is a matte surface or silky surface that can be obtained with ordinary photographic paper as a glossy paper, or when the polyethylene is melt-extruded on the surface of the base paper and coated. It can be used as a surface formed.

A back coat layer can also be provided on the support. Examples of components that can be added to the backcoat layer include white pigments, aqueous binders, 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 backcoat 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 back coat layer include antifoaming agents, foam suppressors, dyes, fluorescent brighteners, preservatives, and water resistance agents.

~~ Method for producing inkjet recording medium ~~
The ink jet recording medium of the present invention comprises, on the support, in order from the support, a preparation liquid for forming an intermediate layer (for example, a coating liquid (hereinafter also referred to as a coating liquid for intermediate layer)) and a preparation for forming an ink receiving layer. It can be prepared by applying a liquid (for example, a coating liquid (hereinafter also referred to as a coating liquid for an ink receiving layer) by coating or the like, and stacking an intermediate layer and an ink receiving layer.

The application amount of the preparation liquid for the ink receiving layer (e.g., the ink-receiving layer coating liquid) (e.g., coating amount) is not particularly limited, but it is 80g ^/ m ² ~230g / m 2 ^{preferably, 100g / m 2 ~200g / m} 2 is more preferable. Furthermore, it as the application amount of preparation for forming the intermediate layer (for example, an intermediate layer coating solution) (e.g. coating amount) is not particularly limited, a 40g ^/ m ² ~200g / m 2 ^preferably, more preferably ^{60g / m 2 ~180g / m 2} .
When the intermediate layer and the ink receiving layer are laminated, the total amount of the preparation liquid (for example, coating liquid) used for forming both layers is not particularly limited, but is 430 g / m ² from the viewpoint of maintaining the quality under low humidity. it is preferably ^less, more preferably ^{100g / m 2 ~350g / m 2} , 120g / m 2 ~330g / m 2 is particularly ^preferably from ^{140g / m 2 ~300g / m 2} . When the total amount is 300 g / m ² or less, the occurrence of curling tends to decrease under low humidity environment conditions.

  Further, it is preferable that the amount of the preparation liquid for forming the intermediate layer (for example, the coating liquid for intermediate layer) is larger than the amount of the preparation liquid for forming the ink receiving layer (for example, the coating liquid for ink receiving layer). This is preferable in terms of curling under the environment. Specifically, the mass ratio between the coating amount of the intermediate layer coating solution and the coating amount of the ink receiving layer coating solution is preferably 97.5: 2.5 to 20:80, and 95: 5 to 20:80. Is more preferable, and 90:10 to 30:70 is particularly preferable.

  When the ink receiving layer coating solution and the intermediate layer coating solution are applied to the support, the ink receiving layer coating solution and the intermediate layer coating solution may be applied simultaneously, or the intermediate layer coating may be performed. After applying the liquid, the ink receiving layer coating liquid may be applied onto the coating layer. In the present invention, it is preferable that the intermediate layer coating solution and the ink receiving layer coating solution are simultaneously applied in a multi-layered manner in that the effect of improving the image density by the polymer plasticizer becomes more remarkable.

  Application of the coating solution for the intermediate layer is a known coating method using an extrusion die coater, slot coater, curtain coater, air doctor coater, bread coater, rod coater, knife coater, squeeze coater, reverse roll coater, bar coater, etc. An extrusion die coater, a slot coater, and a curtain coater are preferable from the viewpoint of simultaneous multilayer coating with the ink receiving layer coating solution. The coating liquid for the ink receiving layer can also be applied by a known coating method using a coater similar to the above, but the coater is not in direct contact with the already formed coating layer, and simultaneous coating is possible. From the possible point, a coating method using an extrusion die coater, a curtain coater, or a bar coater is preferable.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist thereof. Unless otherwise specified, “part” is based on mass.

Example 1
-Production of support-
50 parts of LBKP made of acacia and 50 parts of LBKP made of aspen were each beaten to 340 ml of Canadian freeness by a disc refiner to prepare a pulp slurry. Next, to the obtained pulp slurry, per starch, cationic starch (manufactured by NSC Japan, CAT0304L) 1.3%, anionic polyacrylamide (manufactured by Seiko Chemical Co., Ltd., Polyaclon ST-13) 0.15%, alkyl After adding 0.29% ketene dimer (Arakawa Chemical Co., Ltd., Size Pine K), 0.29% epoxidized behenamide, and 0.32% polyamide polyamine epichlorohydrin (Arakawa Chemical Co., Ltd., Arafix 100), Furthermore, 0.12% of an antifoaming agent was added.

In the process of making the pulp slurry thus prepared with a long paper machine and pressing the felt surface of the web against the drum dryer cylinder through the dryer canvas for drying, the tensile force of the dryer canvas is 1.6 kg / cm. After drying with a size press, 1 g / m ² of polyvinyl alcohol (manufactured by Kuraray Co., Ltd., KL-118) was applied to both sides of the base paper with a size press and dried to perform calendar treatment. The base paper was made with a basis weight of 205 g / m ² to obtain a base paper (base paper) having a thickness of 192 μm.

After the corona discharge treatment is performed on the wire surface (back surface) side of the obtained base paper, a high-density polyethylene is coated so as to be 36 g / m ² using a melt extruder, and a thermoplastic resin layer comprising a mat surface (Hereinafter, this thermoplastic resin layer surface is referred to as a “back surface”). The thermoplastic 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 (manufactured by Nissan Chemical Industries, Ltd.) Of “Snowtex O”) was dispersed in water at a mass ratio of 1: 2 so that the dry weight was 0.2 g / m ² . Subsequently, the front side opposite to the back side was subjected to corona discharge treatment, and a polyethylene having a density of 0.93 g / m ² having 10% by mass of titanium oxide was melted to 40 g / m ² using a melt extruder. Coated and used as a support.

-Preparation of coating liquid A for ink receiving layer-
Of the following “composition of silica dispersion A”, first, (2) ion-exchanged water and (3) dimethyldiallylammonium chloride polymer (Charol DC902P) are mixed with (1) gas phase method silica fine particles. Further, (4) slurry added with zircozole ZA-30 was dispersed at 170 MPa with an optimizer manufactured by Sugino Machine, and a silica dispersion A having a median diameter (average particle diameter) of 120 nm was prepared in one pass. did.

<Composition of silica dispersion A>
(1) Vapor phase silica fine particles: 15.0 parts (Nippon Aerosil Co., Ltd., AEROSIL300SF75)
(2) Ion-exchanged water: 82.9 parts (3) Dimethyldiallylammonium chloride polymer: 1.31 parts (Charol DC-902P (51.5% aqueous solution), manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) ; Dispersing agent)
(4) Zircosol ZA-30 ... 0.81 parts (Daiichi Rare Element Chemical Co., Ltd .; zirconyl acetate)

  Subsequently, among the following “composition of coating liquid A for ink receiving layer”, first, (1) silica dispersion A obtained above was added to (2) ion-exchanged water, and (3) 7.5% boric acid. Liquid, (4) SC-505, (5) Polyvinyl alcohol solution, (6) Superflex 650-5, and (7) Ethanol were sequentially added and mixed to prepare coating solution A for ink receiving layer.

<Composition of coating liquid A for ink receiving layer>
(1) Silica dispersion A 58.7 parts (2) Ion exchange water 5.1 parts (3) 7.5% boric acid solution (crosslinking agent) 5.2 parts ( 4) Dimethylamine / epichlorohydrin / polyalkylenepolyamine polycondensate (50% aqueous solution) (manufactured by Hymo Co., Ltd., SC-505) 0.2 part (5) Polyvinyl alcohol solution 27.5 parts ~ Composition of polyvinyl alcohol solution ~
Polyvinyl alcohol: 6.96 parts (PVA-235, saponification degree 88%, polymerization degree 3500, manufactured by Kuraray Co., Ltd.)
Polyoxyethylene lauryl ether 0.23 part (Emulgen 109P, manufactured by Kao Corporation; surfactant)
・ Diethylene glycol monobutyl ether: 2.12 parts (Butizenol 20P, manufactured by Kyowa Hakko)
・ Ion-exchanged water: 90.69 parts (6) Superflex 650-5 (Daiichi Kogyo Seiyaku Co., Ltd .; cation-modified polyurethane): 2.2 parts (7) Ethanol: 1.1 Part

-Preparation of ink receiving layer coating solution (intermediate layer coating solution) B-
Of the following “composition of silica dispersion B”, first, (2) ion-exchanged water and (3) dimethyldiallylammonium chloride polymer (Charol DC902P) are mixed with (1) gas phase method silica fine particles. In addition, (4) Zircozol ZA-30 added to this slurry, a ceramic sand grinder (manufactured by Shinmaru Enterprises Co., Ltd.) filled with 80% by volume of zirconium oxide (ZrO ₂ ) beads having an average particle diameter of 0.65 mm Using “DYNO-MILL TYPE: KDL-PILOT”), the dispersion was finely dispersed to a median diameter (average particle diameter) of 140 nm to obtain silica dispersion B.

<Composition of silica dispersion B>
(1) Vapor phase silica fine particles: 15.0 parts (Aerosil 300SF75 manufactured by Nippon Aerosil Co., Ltd.)
(2) Ion-exchanged water: 82.9 parts (3) Dimethyldiallylammonium chloride polymer: 1.31 parts (Charol DC-902P (51.5% aqueous solution), manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) ; Dispersing agent)
(4) Zircosol ZA-30 (zirconyl acetate) 0.81 part (Daiichi Rare Element Chemical Co., Ltd.)

  Subsequently, (1) silica dispersion B obtained above was added to (2) ion-exchanged water and (3) 7.5% boric acid so that the following “composition of coating liquid B for ink receiving layer” was obtained. (4) SC-505, (5) Polyvinyl alcohol solution, (6) Superflex 650-5, (7) Ethanol, and (8) Polyethylene glycol are sequentially added and mixed to form an ink-receiving layer. A liquid (intermediate layer coating liquid) B was prepared.

<Composition of coating liquid B for ink receiving layer>
(1) Silica dispersion B 58.7 parts (2) Ion exchange water 5.1 parts (3) 7.5% boric acid solution (crosslinking agent) 5.2 parts ( 4) Dimethylamine / epichlorohydrin / polyalkylene polyamine polycondensate (SC-505 (50% aqueous solution), manufactured by Hymo Co., Ltd.) 0.2 part (5) Polyvinyl alcohol solution 27.5 parts ~ Composition of polyvinyl alcohol solution ~
Polyvinyl alcohol: 6.96 parts (PVA-235, saponification degree 88%, polymerization degree 3500, manufactured by Kuraray Co., Ltd.)
Polyoxyethylene lauryl ether 0.23 part (Emulgen 109P, manufactured by Kao Corporation; surfactant)
・ Diethylene glycol monobutyl ether: 2.12 parts (Butizenol 20P, manufactured by Kyowa Hakko)
・ Ion-exchanged water: 90.69 parts (6) Cation-modified polyurethane: 2.2 parts (Superflex 650-5, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
(7) Ethanol: 1.1 parts (8) Polyethylene glycol (PEG 1000 (molecular weight 1000), manufactured by Toho Chemical Industry Co., Ltd.): 7.0 parts

-Preparation of inkjet recording sheet-
The ink receiving layer coating solution B is allowed to flow on the front surface of the support prepared above so that the coating amount is 130 g / m ² , and further, the coating amount is 130 g / m ² on the top. The ink receiving layer coating liquid A is flowed, and the inline liquid having the following composition is flown so as to have a coating amount of 11.4 g / m ² , so that the ink receiving layer coating liquid A is mixed in-line, and the simultaneous layering is performed using an extrusion die coater. Application was performed. Then, it was dried with a hot air dryer at 80 ° C. (wind speed 3 to 8 m / sec) until the solid content concentration of the coating layer became 20%. At this time, the coating layer showed constant rate drying. And before declining drying, it was immersed in a basic solution (pH = 7.8) having the following composition for 3 seconds to adhere 13 g / m ² of the basic solution on the coating layer, and further at 80 ° C. for 10 minutes. Dried. Thus, an inkjet recording sheet was produced.

<Composition of inline liquid>
・ Basic aluminum 83% polyaluminum chloride aqueous solution 20 parts (Alphain 83, manufactured by Daimei Chemical Co., Ltd.)
・ Ion exchange water: 80 parts

<Composition of basic solution>
・ Boric acid: 0.65 part ・ Ammonium zirconium carbonate (28% aqueous solution): 0.33 part (Zircosol AC-7, manufactured by Daiichi Rare Element Chemical Co., Ltd.)
・ Ammonium carbonate (first grade, manufactured by Kanto Chemical Co., Ltd.) ... 3.5 parts ・ Ion-exchanged water ... 63.3 parts ・ Polyoxyethylene lauryl ether (2% aqueous solution) ... 30.0 parts ( Emulgen 109P, manufactured by Kao Corporation; surfactant)

(Example 2)
In Example 1, the polyethylene glycol (PEG1000) in the ink receiving layer coating solution (intermediate layer coating solution) B was replaced with diglyceryl ether (SC-E1000 (molecular weight 1000), manufactured by Sakamoto Pharmaceutical Co., Ltd.). Except for this, an inkjet recording sheet was produced in the same manner as in Example 1.

(Example 3)
In Example 1, the polyethylene glycol (PEG 1000) in the ink receiving layer coating solution (intermediate layer coating solution) B was replaced with polyglycerin (PGL X (molecular weight: 3000), manufactured by Daicel Chemical Industries, Ltd.). Except for the above, an ink jet recording sheet was produced in the same manner as in Example 1.

Example 4
In Example 1, polyethylene glycol (PEG 1000) in the ink receiving layer coating solution B (intermediate layer coating solution) B was changed to a polyethylene glycol / polypropylene glycol copolymer (Newpol PE-74 (molecular weight: 3400), Sanyo Chemical Industries). An ink jet recording sheet was prepared in the same manner as in Example 1 except that the product was changed to “made by Co., Ltd.”.

(Example 5)
In Example 1, except that the polyethylene glycol (PEG 1000) in the ink receiving layer coating solution (intermediate layer coating solution) B was replaced with polyethylene glycol (PEG 6000 (molecular weight: 6000), manufactured by Toho Chemical Co., Ltd.). In the same manner as in Example 1, an ink jet recording sheet was produced.

(Example 6)
In Example 1, except that the polyethylene glycol (PEG 1000) in the ink receiving layer coating solution (intermediate layer coating solution) B was replaced with polyethylene glycol (PEG 20000 (molecular weight: 20000), manufactured by Toho Chemical Industry Co., Ltd.). In the same manner as in Example 1, an ink jet recording sheet was produced.

(Comparative Example 1)
In Example 1, 7.0 parts of glycerin (molecular weight: 92, manufactured by Kanto Chemical Co., Inc.) is further added to the ink receiving layer coating liquid A, and the ink receiving layer coating liquid (intermediate layer coating liquid) B is added. An inkjet recording sheet was prepared in the same manner as in Example 1 except that glycerin (molecular weight: 92, manufactured by Kanto Chemical Co., Inc.) was used instead of polyethylene glycol (PEG1000).

(Comparative Example 2)
Example 1 except that polyethylene glycol (PEG 1000) in the ink receiving layer coating solution (intermediate layer coating solution) B was replaced with glycerin (molecular weight: 92, manufactured by Kanto Chemical Co., Inc.) in Example 1. In the same manner, an ink jet recording sheet was produced.

(Comparative Example 3)
In Example 1, except that the polyethylene glycol (PEG 1000) in the ink receiving layer coating solution (intermediate layer coating solution) B was replaced with ethylene glycol (molecular weight: 62, manufactured by Kanto Chemical Co., Inc.). In the same manner as in Example 1, an inkjet recording sheet was prepared.

(Comparative Example 4)
In Example 1, except that the polyethylene glycol (PEG 1000) in the ink receiving layer coating solution (intermediate layer coating solution) B was replaced with polyethylene glycol (PEG 600 (molecular weight: 600), manufactured by Toho Chemical Industry Co., Ltd.). In the same manner as in Example 1, an ink jet recording sheet was produced.

(Comparative Example 5)
An ink jet recording sheet was prepared in the same manner as in Example 1, except that polyethylene glycol (PEG 1000) was not added to the ink receiving layer coating solution (intermediate layer coating solution) B.

(Evaluation)
The following evaluation was performed for each of the inkjet recording sheets prepared above. The evaluation results are shown in Table 1 below.

-1. Image density
After the inkjet recording sheet was stored for 24 hours in an environment of 25 ° C. and 50% RH, a black solid image was printed at the maximum density using a printer PM-A700 manufactured by Seiko Epson Corporation. Stored in the environment for 24 hours. Thereafter, the density of the black solid image was measured with X-rite 310 (manufactured by X-rite) and evaluated according to the following evaluation criteria.
<Evaluation criteria>
AA: The concentration was 2.5 or more.
A: The concentration was 2.4 or more and less than 2.5.
B: The concentration was 2.3 or more and less than 2.4.
C: The concentration was 2.2 or more and less than 2.3.

-2. Ink absorption capacity (void capacity)
After penetrating diethylene glycol into the entire ink-receiving layer of each ink jet recording sheet, the diethylene glycol overflowing from the gap is wiped off to obtain the weight difference of the ink jet recording sheet before and after the permeation, and 1 m of the ink jet recording sheet The ink absorption capacity per ² (void capacity) was measured. The ink absorption standard is that the ink absorption capacity (void capacity) is 20 ml / m ² or more. The specific gravity of diethylene glycol was 1.118, and the weight was converted to capacity.
<Evaluation criteria>
AA: The ink absorption capacity was 24 ml / m ² or more.
A: The ink absorption capacity was 23 ml / m ² or more and less than 24 ml / m ² .
B: Ink absorption capacity was less than 22 ml / ^{m 2} or more 23 ml / ^{m 2.}
C: The ink absorption capacity was less than 22 ml / m ² .

-3. Brittleness
Under an environmental condition of a temperature of 10 ° C. and a humidity of 20% RH, an ink jet recording sheet is wound around each of metal rods having different diameters so that the ink receiving layer faces outward, and cracks are generated in the ink receiving layer. The maximum diameter was obtained, and this was used as an index to evaluate brittleness according to the following evaluation criteria.
<Evaluation criteria>
A: Diameter less than 20 mm A: Diameter 20 mm or more, less than 30 mm B: Diameter 30 mm or more, less than 40 mm C: Diameter 40 mm or more

  As shown in Table 1, in the examples, high image density was obtained, and ink absorbability and brittleness were also good. On the other hand, in the comparative example, the image density was inferior, and in Comparative Example 5 in which the polymer plasticizer was not used, the ink absorbability and brittleness were inferior even if the image density was maintained to some extent.

Claims (4)

  An ink jet recording medium comprising an intermediate layer containing a water-soluble polymer plasticizer having a molecular weight of 800 or more and a water-soluble resin, and an ink receiving layer containing inorganic fine particles and a water-soluble resin in this order from the support side.   2. The ink jet recording medium according to claim 1, wherein the polymer plasticizer is at least one selected from polyhydric alcohols and ethers thereof.   The inkjet according to claim 1 or 2, wherein the polymer plasticizer is at least one of polyglycerin, diglyceryl ether, polyethylene glycol, and a copolymer of polyethylene glycol and polypropylene glycol. recoding media.   The inkjet recording medium according to any one of claims 1 to 3, wherein the intermediate layer further contains inorganic fine particles.