JP2005297550A - Supporting article for image recording material and image recording material using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a supporting article for an image recording material having high whiteness and to provide an image recording material excellent in whiteness (particularly whiteness in a non-imaging part). <P>SOLUTION: A supporting article for an image recording material comprises a pigment layer containing a white pigment and a fluorescent brightening agent layer containing a fluorescent brightening agent in this order on a substrate, and an image recording material is prepared from the supporting article. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an inkjet recording medium having an ink receiving layer, a digital electrophotographic image receiving material having a toner image receiving layer, a silver salt photographic photosensitive material having a silver salt photographic photosensitive layer, a sublimation transfer image receiving material having a sublimation transfer image receiving layer, The present invention relates to a thermal recording material having a thermal coloring layer, an image recording material support used for an image recording material including a thermal transfer image receiving material having a thermal transfer image receiving layer, and an image recording material using the same.

  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 processing 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 and the development of hardware (devices), various types of inkjet recording media have been developed, and in recent years it has become possible to obtain so-called photographic-like high-quality recorded matter. .
In particular, the characteristics required for ink jet recording media generally include (1) fast drying (high ink absorption speed), and (2) proper and uniform ink dot diameter (similar to (3) Good granularity, (4) High dot roundness, (5) High color density, (6) High saturation (no blurring) (7) The light resistance, gas resistance and water resistance of the printed part are good, (8) the whiteness of the recording surface is high, and (9) the preservability of the recording medium is good (yellow during long-term storage). No discoloration, image does not bleed after long-term storage), (10) good deformation and good dimensional stability (curl is sufficiently small), and (11) good hard running performance. Etc. In addition to the above properties, glossy paper, surface smoothness, and photographic paper-like texture similar to silver salt photography are also required for photo glossy paper used for the purpose of obtaining so-called photo-like high-quality recorded material. Is done.

  For example, there is an ink jet recording sheet that includes fine inorganic pigment particles and a water-soluble resin and has a porous colorant receiving layer having a high porosity provided on a support (for example, Patent Documents 1 and 2). reference.). These recording sheets, particularly ink jet recording sheets provided with a colorant-receiving layer having a porous structure using silica as inorganic pigment fine particles, are excellent in ink absorbability depending on the configuration, and form high-resolution images. It is said that it has a high ink receiving performance and also exhibits a high gloss.

  Conventionally, resin-coated paper in which both sides of a paper substrate are laminated with polyethylene resin has been generally used as a support constituting an inkjet recording medium in order to provide high-quality characteristics with glossiness and flatness. It was. However, since this resin-coated paper does not absorb the ink solvent in the applied ink, when it is stored in a file immediately after printing, the image does not evaporate and is left behind due to the remaining ink solvent. There is a problem of bleeding.

  In order to prevent such blurring of the image, it is also conceivable to form a medium for ink jet recording using a support having no resin coating. However, if the ink receiving layer is provided as it is on an absorbent support such as a paper substrate that is currently distributed, the aging blur is reduced by the absorption of the ink solvent, but the surface glossiness is remarkably lowered. End up.

  On the other hand, using a resin-coated paper having a resin layer, a halogenation in which a layer containing at least a water-soluble polymer mainly composed of gelatin and ultrafine titanium dioxide is provided between the support and the photosensitive silver halide emulsion. Silver photographic light-sensitive materials have been proposed (see, for example, Patent Document 3). Such a silver halide photographic light-sensitive material is intended to improve resolution and luminance and to improve light resistance. However, such a silver halide photographic light-sensitive material is assumed to contain gelatin as a water-soluble resin, and there is no viewpoint of preventing the above-mentioned aging blur.

  On the other hand, an inkjet recording paper in which a fluorescent whitening agent layer containing at least a fluorescent whitening agent, polyvinyl alcohol having a saponification degree of 95% or more and an ink receiving layer are sequentially accumulated on a base paper has been proposed (for example, (See Patent Document 4). Such an ink jet recording sheet may contain a pigment in the fluorescent brightening agent layer. However, when such ink jet recording paper does not contain a pigment, the shielding property of the fluorescent brightening agent layer is low, and it is greatly influenced by the color of the base paper. Even when a pigment is included, the fluorescent whitening agent and the pigment are contained in the same layer. There was a problem that the function was disturbed.

  It is also conceivable to increase the whiteness of the ink jet recording medium by adding a fluorescent brightening agent to the ink receiving layer. However, if a fluorescent whitening agent is contained in the ink receiving layer, the pigment having high surface activity contained in the ink receiving layer and the fluorescent whitening agent react to turn yellow, and the whiteness of the ink jet recording medium is rather reduced. It will decrease.

  As described above, the whiteness of the support itself is improved by the following: a digital electrophotographic image receiving material having a toner image receiving layer, a silver salt photographic photosensitive material having a silver salt photographic photosensitive layer, and a sublimation transfer image receiving material having a sublimation transfer image receiving layer. It is required for a support for an image recording material used for an image recording material other than an inkjet recording medium such as a thermal recording material having a thermosensitive coloring layer and a thermal transfer image receiving material having a thermal transfer image receiving layer. Many developments of an image recording material support have been desired.

JP 10-119423 A Japanese Patent Laid-Open No. 10-217601 JP-A-2003-43631 JP 2003-94799 A

  The present invention has been made in view of the above, and an object of the present invention is to provide a support for an image recording material having high whiteness and an image recording material having excellent whiteness (particularly whiteness of a non-image portion). And

The above problem is solved by the following means.
<1> A support for an image recording material, which comprises a pigment layer containing a white pigment and a fluorescent whitening layer containing a fluorescent whitening agent in this order on a substrate.

  <2> The support for an image recording material according to <1>, wherein the white pigment is titanium dioxide.

  <3> The support for an image recording material according to <1> or <2>, wherein the fluorescent whitening agent is a water-soluble fluorescent whitening agent.

  <4> The support for an image recording material according to <3>, wherein the water-soluble fluorescent whitening agent is a stilbene compound.

  <5> The support for an image recording material according to <1> to <4>, wherein the pigment layer contains a thermoplastic resin.

  <6> The support for an image recording material according to <5>, wherein the thermoplastic resin is a water-dispersible latex.

  <7> The fluorescent whitening layer is a support for an image recording material according to the above <1> to <6>, which contains a thermoplastic resin.

  <8> The support for an image recording material according to <7>, wherein the thermoplastic resin is a water-dispersible latex.

  <9> The support for an image recording material according to <1> to <8>, wherein the pigment layer and the fluorescent whitening layer are formed on the substrate by a simultaneous multilayer coating method. .

  <10> An image recording material comprising: the image recording material support according to the above <1> to <9>, and a recording layer provided on the fluorescent whitening layer of the image recording material support. It is.

  <11> The above <10>, wherein the recording layer is any one of an ink receiving layer, a toner image receiving layer, a silver salt photographic photosensitive layer, a sublimation transfer image receiving layer, a heat sensitive color developing layer, and a thermal transfer image receiving layer. This is an image recording material.

According to the present invention, it is possible to provide a support for an image recording material having high whiteness and an image recording material having excellent whiteness (particularly whiteness of a non-image portion).
The support for an image recording material of the present invention exhibits good ink absorbability, particularly when an ink receiving layer is provided, and can effectively suppress the occurrence of aging blur in the formed image. .

<Support for image recording material>
The support for an image recording material of the present invention is characterized by having a pigment layer containing a white pigment and a fluorescent whitening layer containing a fluorescent whitening agent in this order on a substrate.
The support for image recording material of the present invention (hereinafter sometimes referred to as “support of the present invention”) has a pigment layer containing a white pigment and a fluorescent whitening layer containing a fluorescent whitening agent. . By including the fluorescent whitening agent in a layer different from the layer containing the white pigment or the ink receiving layer as described above, the effect of the fluorescent whitening agent can be sufficiently exerted and the whiteness can be increased. Can do. Thereby, the whiteness (especially the whiteness of a non-image part) of the image recording material using the support body of this invention can be improved.

  In addition, the support of the present invention is provided in the order of the pigment layer and the fluorescent whitening layer (hereinafter sometimes collectively referred to as “the undercoat layer in the present invention”) from the base material side. As a result, it is possible to prevent the ultraviolet whitening light from being absorbed by the white pigment and inhibiting the fluorescent whitening ability of the fluorescent whitening agent. That is, when an image forming material is formed using the support of the present invention, a recording layer is provided on the side where the undercoat layer (pigment layer and fluorescent whitening layer) of the support of the present invention is provided. When the fluorescent whitening layer and the pigment layer are provided in this order from the substrate side, the white pigment in the pigment layer absorbs ultraviolet light when observed from the recording surface side, and the fluorescent whitening The effect of the layer cannot be exhibited sufficiently.

  Further, ink permeability can be imparted to the pigment layer and the fluorescent whitening layer. For this reason, when an absorptive base material is used as the base material, an ink jet recording medium having good ink absorptivity can be produced by providing an ink receiving layer on the undercoat layer in the present invention. As described above, the ink jet recording medium using the support of the present invention is excellent in ink absorbability, and the occurrence of blurring with time is effectively suppressed.

  As described above, the support of the present invention is suitably used for various image recording materials in which a recording layer is provided on the support. In this case, examples of the recording layer provided on the undercoat layer in the present invention include an ink receiving layer, a toner image receiving layer, a silver salt photographic photosensitive layer, a sublimation transfer image receiving layer, a heat sensitive color developing layer, and a heat transfer image receiving layer. . That is, the support of the present invention is an inkjet recording medium in which the recording layer is an ink receiving layer, a digital electrophotographic image receiving material in which the recording layer is a toner image receiving layer, and the recording layer is a silver salt photographic photosensitive layer. It can be particularly suitably used for silver salt photographic light-sensitive materials, heat-sensitive recording materials in which the recording layer is a heat-sensitive color developing layer, and thermal transfer image-receiving materials in which the recording layer is a thermal transfer image-receiving layer. The present invention is not limited to these, and any image recording material having a recording layer on a support can be used without limitation.

  The support of the present invention has an undercoat layer in the present invention on a substrate, and if necessary, a backcoat layer on the surface opposite to the side on which the undercoat layer in the present invention is provided. Good.

  Further, the support of the present invention preferably has a whiteness defined by JIS-L1916 (2000) of the surface on which the recording layer is provided (the surface on the side on which the undercoat layer is provided) of 130 or more. 140 or more.

<Undercoat layer>
As described above, the support of the present invention has a structure in which a pigment layer and a fluorescent whitening layer are laminated in this order from the support side as an undercoat layer on a substrate.
The thickness of the pigment layer is preferably 1 to 30 μm and more preferably 3 to 20 μm from the viewpoint of waterproofness and ink permeability.
As the fluorescent whitening layer, concentration quenching (if the fluorescent whitening agent concentration in the fluorescent whitening layer is too high, energy transfer between the fluorescent whitening agents is more dominant than fluorescence emission, making it difficult to obtain fluorescence intensity). From the viewpoint, the fluorescent whitening agent coating amount in the fluorescent whitening layer is preferably 1 to 20% by mass, and more preferably 3 to 10% by mass. Further, the thickness of the fluorescent whitening layer is preferably as thin as possible from the viewpoint of cost, and preferably 1 to 10 μm.
The undercoat layer (the sum of the thickness of the pigment layer and the thickness of the fluorescent whitening layer) is preferably from 1 to 40 μm, more preferably from 3 to 20 μm, from the viewpoint of waterproofness and ink absorbability.

  In order to give the support of the present invention ink solvent absorbability, it has ink solvent permeability such as water-dispersible latex as a binder for the undercoat layer (pigment layer / fluorescent whitening layer) in the present invention. It is preferable to use a binder.

(Pigment layer)
The pigment layer is a layer containing a white pigment, and further includes a binder.

-White pigment-
Examples of the white pigment contained in the pigment layer include titanium dioxide, titanium oxide, barium sulfate, barium carbonate, calcium carbonate, lithopone, alumina white, zinc oxide, silica antimony trioxide, titanium phosphate, kaolin, clay, and baking. Examples include clay, aluminum oxide, aluminum hydroxide, aluminum silicate, colloidal silica, zeolite, synthetic zeolite, sepiolite, sukumite, synthetic sukumite, magnesium silicate, magnesium carbonate, magnesium oxide, diatomaceous earth, styrene resin pigment, and benzoguanamine resin pigment. It is done. These can be used individually by 1 type or in mixture of 2 or more types.

  The average particle size of the white pigment is preferably 0.05 to 20 μm, more preferably 0.1 to 10 μm. Here, the “average particle diameter” means an area average particle diameter, and is calculated from the number average by regarding the diameter of the particle as a circle equivalent to the projected area of each particle. When the average particle diameter of the white pigment is in the range of 0.05 to 20 μm, the whiteness and gloss can be effectively improved.

  Further, the “ultrafine particle titanium dioxide” means titanium dioxide having an average particle diameter of 100 nm or less. That is, the ultrafine particle titanium dioxide is an ultrafine particle whose primary particle diameter is one or more orders of magnitude smaller than the conventional pigment called “titanium white”. For this reason, light scattering is suppressed, transparency is high, and an ultraviolet-absorbing ability is also significantly high.

  The average particle diameter of the titanium dioxide is preferably 20 nm or less, more preferably 15 nm or less, and particularly preferably 10 nm or less from the viewpoints of improving the gloss of the coated surface and increasing the ink absorbability. The particle size distribution of the titanium dioxide is monodispersed with a coefficient of variation (the standard deviation of the particle size distribution divided by the average particle size) of 20% or less, preferably 15% or less, more preferably 10% or less. It is preferable that

  The titanium dioxide can be produced by subjecting a titanium salt to a treatment such as hydrolysis or gas phase oxidation. The titanium dioxide may have any of the rutile, brookite, and anatase crystal structures, and the rutile type is particularly preferable from the viewpoint of the reflectance of visible light.

  Further, the titanium dioxide may be subjected to surface treatment with an inorganic compound or an organic compound in order to improve dispersibility and workability. Examples of the surface treatment include those disclosed in JP-A Nos. 52-35625, 55-10865, 57-35855, 62-25553, 62-103635, and JP-A-9-050093. What and methods can be used. For the surface treatment, an inorganic compound such as aluminum oxide hydrate, hydrous zinc oxide, or silicon dioxide, or an organic compound such as divalent to tetravalent alcohol, trimethylolamine, titanate coupling agent or silane coupling agent is used. It can be preferably used as a treating agent. The amount of these surface treatment agents used can be selected according to the purpose. For example, in the case of the above-mentioned inorganic surface treatment agent, the range of about 3% by mass or less is common with respect to ultrafine titanium dioxide, and the range of 0.01 to 1% by mass is preferable. Moreover, in the case of the said organic compound, the range of about 5 mass% or less is common, and the range of 0.1-3 mass% is preferable.

  As said titanium oxide, any of a rutile type and an anatase type can be used, and these can be used individually or in mixture. Further, the titanium oxide may be either one produced by the sulfuric acid method or one produced by the chlorine method. Examples of the titanium oxide include hydrous alumina treatment, hydrous silicon dioxide treatment, or surface coating treatment with an inorganic substance such as zinc oxide treatment, trimethylolmethane, trimethylolethane, trimethylolpropane, and 2,4-dihydroxy-2. -It can select suitably from what carried out surface coating processing by organic substances, such as methylpentane, or siloxane processing, such as polydimethylsiloxane.

  The refractive index of the white pigment is preferably 1.5 or more, and more preferably 2.0 or more. When a white pigment having a refractive index in this range is included, a high-quality image can be formed.

Furthermore, the specific surface area of the white pigment by the BET method is preferably less than 400 m ² / g. When the critical area by the BET method of the white pigment is less than 400 m ² / g, it is possible to suppress the penetration of the coating liquid when the color material receiving layer is formed by coating.
Here, the “BET method” is one of powder surface area measurement methods by a gas 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 the 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. Prominent expressions representing the isotherm of multimolecular adsorption include Brunauer Emmett and Teller's equation (BET equation). Based on this, the amount of adsorption is obtained, and the surface area is calculated by multiplying the area occupied by one adsorbed molecule on the surface. be able to.

The content of the white pigment in the pigment layer varies depending on the type of white pigment, the type of binder, the layer thickness, and the like, but is usually preferably 20 to 500% by mass with respect to the binder in the pigment layer.
Further, the coating amount of the pigment layer is preferably 1 to 30 g / m ² from the viewpoint of preventing the coating liquid from permeating and enhancing the ink absorbency when the support of the present invention is used for an ink jet recording medium. 3 to 20 g / m ² is more preferable.
In addition, well-known additives, such as antioxidant, can also be added to the said pigment layer.

-Binder-
As the binder used in the pigment layer, a known binder can be appropriately selected and used in consideration of the combination with the white pigment as long as the effects of the present invention are not impaired.
The support of the present invention preferably contains a thermoplastic resin as the binder, particularly from a particulate thermoplastic resin, from the viewpoint of achieving both prevention of dyeing of the coating liquid and ink absorbability when forming the ink receiving layer. It is preferable to use it.

-Thermoplastic resin-
The support of the present invention preferably uses a thermoplastic resin as a binder together with a fluorescent whitening layer and a pigment layer when a paper base material such as a base paper is used as the base material. When an ink receiving layer is provided on the support of the present invention having such a configuration to form an ink jet recording medium, the pigment layer containing the thermoplastic resin exhibits high ink solvent permeability. Therefore, the ink solvent contained in the ink Can be absorbed by the paper base material, and the occurrence of aging blur can be effectively suppressed.

  There is no restriction | limiting in particular as said thermoplastic resin, From what made the microparticles | fine-particles of well-known thermoplastic resins, such as polyolefin resin (For example, the homopolymer of alpha olefins, such as polyethylene and a polypropylene, or these mixtures), or its latex. It can be appropriately selected and used. Among these, water-dispersible latex is preferable as the thermoplastic resin. Examples of the water-dispersible latex include acrylic latex, acrylic silicone latex, acrylic epoxy latex, acrylic styrene latex, acrylic urethane latex, styrene-butadiene latex, acrylonitrile-butadiene latex, and vinyl acetate. Latex and the like can be preferably mentioned, and at least one of them is preferably selected and used.

Specific examples of the thermoplastic resin include hybrid emulsion Aquabrid series (for example, Aquabrid UM7760, UM7611, UM4901, MSi-045, ASi-753, ASi-903, ASi manufactured by Daicel Chemical Industries, Ltd.) -89, ASi-91, etc.).
In addition, said thermoplastic resin can also use together 2 or more types not only individually by 1 type. Moreover, as a binder which can be used for the pigment layer in this invention, not only the said thermoplastic resin but water-soluble resin, such as polyvinyl alcohol, etc. can be used.

  As the water-soluble resin, polyvinyl alcohol is preferable. Specifically, completely saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, silanol-modified polyvinyl alcohol, carboxyl A group-modified polyvinyl alcohol, an aromatic amino group-modified polyvinyl alcohol, a thiol group-modified polyvinyl alcohol, and a ketone group-modified polyvinyl alcohol are preferable, and the polyvinyl alcohol of the same type as the polyvinyl alcohol used in the recording layer is more preferable.

  In addition, when the ink solvent absorbability is imparted to the support of the present invention, it is preferable to use the above-mentioned water-dispersible latex or water-soluble resin as the binder. Specific examples of the water-dispersible latex include acrylic latex, acrylic silicon latex, acrylic epoxy latex, acrylic styrene latex, acrylic urethane latex, styrene-butadiene latex, acrylonitrile-butadiene latex, and Suitable examples include at least one selected from vinyl acetate latexes. Among the above water-dispersed latexes, it is selected from acrylic latex, acrylic silicone latex, and acrylic styrene latex from the viewpoint of having high ink solvent permeability and waterproofing effects, and being able to combine economic efficiency and manufacturing suitability. At least one of these is preferred.

  The glass transition temperature (Tg) of the binder is preferably 5 to 70 ° C, particularly preferably 15 to 70 ° C. When the Tg is in the range of 5 to 70 ° C., the pigment layer forming liquid (coating liquid and the like) is excellent in handling in production without causing problems such as burrs. Furthermore, it is not necessary to set the calendar temperature high when performing calendar processing, so that it is easy to obtain a desired gloss and adhesion to the surface of the metal roll is difficult to occur. .

  Moreover, as the minimum film-forming temperature of the said binder, 5-60 degreeC is preferable and 10-50 degreeC is still more preferable. When a thermoplastic resin having a minimum film forming temperature range of 5 to 60 ° C. is used, it is excellent in handling in production without causing problems such as burrs of the liquid for forming the pigment layer (coating liquid and the like).

  As content of the said binder in the said pigment layer, 15-95 mass% is preferable with respect to solid content in the said pigment layer, and 30-90 mass% is still more preferable. When the content is in the range of 30 to 90% by mass, ink solvent permeability can be obtained when an ink receiving layer is provided without impairing gloss and flatness after calendering described below. Thus, the occurrence of aging blur can be more effectively prevented.

  The pigment layer can be formed using a dispersion solution when the thermoplastic resin is used. For example, (1) a dispersion solution prepared by further dispersing a white pigment in a thermoplastic solvent dispersed in a desired solvent, or (2) a dispersion liquid in which a thermoplastic resin is dispersed and a white pigment are dispersed. It can be formed by, for example, coating on a paper substrate by a known method using a dispersion solution prepared by mixing with the dispersion liquid.

  When the pigment layer is formed by coating, for example, according to (2) above, a latex dispersion in which a thermoplastic resin is previously dispersed in water and a pigment dispersion in which a white pigment is dispersed in water are prepared, It is preferable to prepare a coating liquid for forming a pigment layer (hereinafter sometimes referred to as “coating liquid for a pigment layer”) that is mixed and stirred to make uniform by mixing and stirring as necessary. In the case of (1) above, one of the thermoplastic resin and the white pigment is dispersed in water, and the other (along with other components if necessary) is further dispersed and further dispersed and homogenized. It is preferable to prepare a layer coating solution. The pigment layer can be formed by applying and drying these prepared coating liquids on a paper substrate (preferably simultaneously with the fluorescent whitening layer coating liquid described later) by a known coating method.

  In addition to the coating method, the pigment layer can be provided by immersing the paper substrate in a pigment layer coating solution or by spraying the pigment layer coating solution onto the paper substrate.

  The application of the coating liquid for the pigment layer can be more suitably performed by a known application method such as a blade coating method, a bar coating method, a spray coating method, or a curtain coating. The solid content concentration of the pigment layer coating solution is desirably in the range of 15 to 65% by mass.

-Fluorescent whitening layer-
The fluorescent whitening layer is a layer containing a fluorescent whitening agent, and is further formed including a binder.
Examples of the fluorescent whitening agent contained in the fluorescent whitening layer include K.I. The compounds described in Vene-Rataramann, “The Chemistry of Synthetic Dies”, Volume V, Chapter 8, can be used. More specifically, examples include stilbene compounds, coumarin compounds, biphenyl compounds, benzoxazolyl compounds, naphthalimide compounds, pyrazoline compounds, carbostyril compounds, and the like.
Hereinafter, the above-mentioned fluorescent brightening agent will be described separately according to its solubility into a water-soluble fluorescent brightener and an oil-soluble fluorescent brightener. From the viewpoint of handleability, a water-soluble fluorescent whitening agent is preferable.

Examples of the water-soluble fluorescent whitening agent include stilbene compounds having a water-soluble group described in, for example, U.S. Pat. No. 2,933,390, Japanese Patent Publication No. 48-30495, and Japanese Patent Application Laid-Open No. 55-135833. Is preferred. Among these, a water-soluble diaminostilbene compound is particularly preferable, and a compound having a sulfone group as the water-soluble group is more preferable.
In particular, fluorescent whitening agents including 4,4′-diaminostilbene disulfonic acid derivatives are, for example, ordinary fluorescent whitening agents (published in August, 1976) edited by Chemical Industry Association. It can be synthesized by the method.
The water-soluble optical brightener can be added as an aqueous solution.

  As the oil-soluble fluorescent brightening agent, substituted stilbenes, substituted coumarins described in British Patent 786,234, substituted thiophenes described in US Pat. No. 3,135,762 are particularly useful. In addition, fluorescent whitening agents such as those disclosed in JP-B-45-37376 and JP-A-50-126732 can be advantageously used.

When using the oil-soluble fluorescent whitening agent, a method of adding as an emulsified dispersion or a latex dispersion is mainly used.
The emulsification dispersion method can be prepared, for example, by dissolving the oil-soluble fluorescent whitening agent in a high-boiling organic solvent or a water-insoluble polymer and emulsifying and dispersing it. Specifically, a method in which an oil-soluble fluorescent whitening agent is dissolved in a high boiling point organic solvent as exemplified in British Patent No. 1072915, and this is emulsified and dispersed together with a surfactant in a hydrophilic colloid such as gelatin. There is. As the high boiling point solvent, in addition to phthalic acid esters and phosphoric acid esters, amide compounds, benzoic acid esters, substituted paraffins and the like can be used. In addition, an emulsified dispersion can be prepared in the same manner as described above by using a water-insoluble polymer such as polyurethane or polyacrylic acid ester instead of the high boiling point organic solvent.

  As a method for preparing the latex dispersion, an oil-soluble fluorescent whitening agent is dissolved in a monomer in advance and polymerized to form a latex dispersion, or an auxiliary solvent is used in a hydrophobic polymer to form an oil-soluble fluorescent whitening agent. There is a method of impregnating an agent to form a latex dispersion. These are disclosed, for example, in JP-A-50-126732, JP-B-51-47043, U.S. Pat. Nos. 3,418,127, 3,359,102, 3,558,316, and 3,788. , 854, and the like.

  Specific examples of the fluorescent whitening agent preferably used in the present invention include compound examples K-1 to K-57 described in Japanese Patent No. 2717869, but the present invention is not limited thereto. It will never be done.

The fluorescent whitening agent contained in the fluorescent whitening layer in the present invention is preferably a water-soluble fluorescent whitening agent from the viewpoint of high solubility in a hydrophilic binder and easy obtaining of sufficient fluorescence intensity.
When the water-soluble fluorescent whitening agent is used, the content of the fluorescent whitening agent in the fluorescent whitening layer is preferably 1 to 20% by mass with respect to the solid content in the fluorescent whitening layer, and 3 to 10% by mass. % Is more preferable. Moreover, when using an oil-soluble fluorescent whitening agent, 0.5-10 mass% is preferable with respect to solid content in a fluorescent whitening layer, and 1-5 mass% is more preferable.
When the content of the water-soluble and oil-soluble fluorescent brightening agent is within the above-mentioned range, a decrease in fluorescence intensity called concentration quenching hardly occurs, and a necessary and sufficient fluorescence intensity can be obtained.

-Fluorescent brightener dyeing agent-
In the present invention, from the viewpoint of preventing diffusion of the fluorescent whitening agent into other layers and improving water resistance, the fluorescent whitening layer can contain a fluorescent whitening agent dye together with the fluorescent whitening agent. Examples of the fluorescent brightener dyeing agent include Japanese Patent Publication Nos. 43-13498, 43-22882, U.S. Pat. Nos. 3,052,544, 3,666,470, and 3,167,429. Nos. 3,168,403 and 3,252,801, N-vinylpyrrolidone polymers, U.S. Pat. Nos. 2,448,507 and 2,448. , 508, 2,721,852, pyridine-based polymers, U.S. Pat. No. 3,341,332, morpholine-based polymers, U.S. Pat. An oxazolidine-based polymer, a polyvinyl alcohol-based polymer, or the like described in 006,762 can be used. Of these, water-soluble or water-dispersible resins containing vinyl pyrrolidone and vinyl alcohol are most preferable.

  As content in the fluorescent whitening layer in this invention of the said fluorescent whitening agent dyeing agent, 5-100 mass% is preferable with respect to a binder, and 25-100 mass% is especially preferable. When the content of the fluorescent brightener colorant is within the above range, the dyeing property of the fluorescent brightener is sufficiently achieved, and the whiteness and yellow density are less likely to occur.

-Binder-
As the binder used in the fluorescent whitening layer, a known binder can be appropriately selected and used in consideration of the combination with the fluorescent whitening agent and the like as long as the effects of the present invention are not impaired.
The fluorescent whitening layer preferably contains a thermoplastic resin as the binder from the viewpoint of achieving both the prevention of dyeing of the coating liquid and the ink absorptivity during the formation of the ink receiving layer, and in particular, a particulate thermoplastic resin. Is preferably used.
Examples of the thermoplastic resin that can be used for the fluorescent whitening layer include those similar to the thermoplastic resin that can be used for the pigment layer described above. Similarly, a water-dispersible latex is preferable, and other preferable physical properties are also included. It is the same.

  Similar to the pigment layer, the binder that can be used in the fluorescent whitening layer is not limited to the thermoplastic resin, and a water-soluble resin can be used. Examples of the water-soluble resin include the same water-soluble resins that can be used as the binder for the pigment layer.

  In addition, when the ink solvent absorbability is imparted to the support of the present invention, it is preferable to use the above-mentioned water-dispersible latex or water-soluble resin as the binder. Specific examples of the water-dispersible latex include acrylic latex, acrylic silicon latex, acrylic epoxy latex, acrylic styrene latex, acrylic urethane latex, styrene-butadiene latex, acrylonitrile-butadiene latex, and Suitable examples include at least one selected from vinyl acetate latexes. Among the above water-dispersed latexes, it is selected from acrylic latex, acrylic silicone latex, and acrylic styrene latex from the viewpoint of having high ink solvent permeability and waterproofing effects, and being able to combine economic efficiency and manufacturing suitability. At least one of these is preferred.

  As content of the said binder in the said fluorescent whitening layer, 15-95 mass% is preferable with respect to solid content in the said fluorescent whitening layer, and 30-90 mass% is still more preferable. When the content is in the range of 30 to 90% by mass, ink solvent permeability can be obtained when an ink receiving layer is provided without impairing gloss and flatness after calendering described below. Thus, the occurrence of aging blur can be more effectively prevented.

  The fluorescent whitening layer can be formed using a dispersion solution. For example, (1) a fluorescent whitening agent (aqueous solution) is further dispersed in a thermoplastic solvent in a desired solvent, or (2) a dispersion in which a thermoplastic resin is dispersed and a fluorescent whitening agent (aqueous solution). Using a dispersion solution prepared by mixing or the like, it can be formed, for example, by coating or the like on a pigment layer formed on a paper substrate by a known method.

  When the fluorescent whitening layer is formed by coating, for example, according to the above (2), a latex dispersion liquid in which a thermoplastic resin is dispersed in water and an optical brightening agent (aqueous solution) are prepared, and these are (necessary) It is preferable to prepare a coating liquid for forming a fluorescent whitening layer (hereinafter, also referred to as “fluorescent whitening layer coating liquid”) that is mixed and stirred to make it uniform with other components. In the case of (1) above, one of the thermoplastic resin and the fluorescent brightening agent (aqueous solution) is dispersed in water, and the other is added (along with other components if necessary) to further disperse. It is preferable to prepare a fluorescent whitening layer coating solution that is uniformized. A pigment layer can be formed by applying and drying these prepared coating solutions on a pigment layer formed on a paper substrate (preferably simultaneously with the pigment layer coating solution) by a known coating method. .

  In the present invention, from the viewpoint of manufacturing cost reduction, it is particularly preferable that the pigment layer and the fluorescent whitening layer are formed on a substrate by a simultaneous multilayer coating method using an extrusion die coater, a curtain flow coater or the like. .

  In addition to the above-described coating method, the fluorescent whitening layer may be obtained by immersing a paper base material in which a pigment layer is formed in the fluorescent whitening layer coating solution, or by applying the fluorescent whitening layer coating solution on the paper base material. It can also be provided by spraying on the formed pigment layer.

  The application of the fluorescent whitening layer coating solution can be more suitably performed by a known coating method such as a blade coating method, a bar coating method, a spray coating method, or a curtain coating method. The solid content concentration of the pigment layer coating solution is desirably in the range of 15 to 65% by mass.

-Calendar processing-
The support of the present invention is a calender in which at least one of a roll pair is composed of a metal roll (preferably composed of a metal roll and a resin roll) after forming a fluorescent whitening layer (undercoat layer in the present invention). (Soft calender and / or super calender) is used to make the surface temperature of the metal roll equal to or higher than the glass transition temperature of the thermoplastic resin fine particles, and the nip pressure of the roll pair is set to 50 to 400 kg / cm for calender treatment. It is preferable to apply.

  As described above, after providing the undercoat layer of the present invention on the substrate, the surface of the recording layer formed through the fluorescent whitening layer is highly glossy and highly flat by performing calendar treatment under specific conditions. In the case where the recording layer is an ink receiving layer at the same time, the absorbability of the ink solvent in the ink applied to the ink receiving layer at the time of printing is increased, and the formed image is secured. It is possible to effectively suppress the bleeding (aging blur) over time.

  As described above, at least one of the roll pair is composed of a metal roll (preferably composed of a metal roll and a resin roll), a super calender, or both, and the calendar treatment is performed using the metal. It is preferable that the surface temperature of the roll is set to be equal to or higher than the glass transition temperature of the thermoplastic resin fine particles described above, and the nip pressure between the roll nips in the roll pair is 50 to 400 kg / cm.

  Hereinafter, a soft calendar having a metal roll and a resin roll and a super calendar will be described in detail. The metal roll is a cylindrical or columnar roll having a smooth surface, and is appropriately selected from known metal rolls without being limited to the material and the like as long as it has a heating means inside. Can be used. Further, since the metal roll is in contact with the recording surface side, that is, the surface on the side where an ink receiving layer described later is formed, on both sides of the support during calendering, the surface roughness is preferably as smooth as possible. Specifically, the surface roughness is preferably 0.3 s or less, more preferably 0.2 s or less, in terms of the surface roughness specified by JIS B0601.

  The surface temperature during the treatment of the metal roll is generally preferably 70 to 250 ° C. when the raw paper is treated. On the other hand, when the paper substrate provided with the undercoat layer in the present invention is treated, it is preferably not less than the glass transition temperature Tg of the thermoplastic resin fine particles contained in the undercoat layer. More preferably, the temperature is + 40 ° C. or lower.

As said resin roll, it can select suitably from the synthetic resin roll which consists of a polyurethane resin, a polyamide resin, etc., and the thing whose Joard D hardness is 60-90 is suitable.
Further, the nip pressure of the roll pair having the metal roll is appropriately 50 to 400 kg / cm, and preferably 100 to 300 kg / cm. In the case of a process using a soft calendar and / or a super calendar in which a pair of rolls configured as described above is arranged, it is desirable to be performed about once or twice.

  As described above, by using a paper substrate, which will be described later, as a substrate, when the image forming material of the present invention is an inkjet recording medium, the ink solvent in the applied ink can be absorbed. Ink solvent that remains without being vaporized immediately after printing by eliminating the deterioration of glossiness, flatness, and high-quality image forming properties due to the use of a paper base material, and simultaneously imparting solvent permeation ability to the layer It is possible to effectively avoid aging blur caused by.

<Base material>
Next, the substrate will be described. As the substrate in the present invention, a solvent non-absorbent support such as a resin-coated paper whose base paper is coated with polyethylene, a solvent-absorbable support such as paper, and the like can be used without limitation.

-Paper substrate-
A paper base material can be used as the base material in the present invention. In this case, it is preferable to use the above-mentioned thermoplastic resin as a binder for the undercoat layer in the present invention. When a paper base material is used as the base material, the paper base material is allowed to absorb the ink solvent that has permeated through the undercoat layer in the present invention containing the thermoplastic resin by utilizing the liquid absorbing ability inherent in the paper material. Can do.

  Examples of the paper base include natural pulp paper mainly composed of normal natural pulp, mixed paper composed of natural pulp and synthetic fiber, synthetic fiber paper mainly composed of synthetic fiber, polystyrene, polyethylene terephthalate, polypropylene, etc. Any of the so-called synthetic papers obtained by converting the synthetic resin film into pseudo paper may be used, but natural pulp paper (hereinafter simply referred to as “base paper”) is particularly preferable. The base paper may be neutral paper (pH 5-9) or acidic paper, but neutral paper is preferred.

  The above-mentioned base paper is made from natural pulp selected from conifers, hardwoods, etc., as necessary, fillers such as clay, talc, calcium carbonate, urea resin fine particles, rosin, alkyl ketene dimer, higher fatty acid, epoxidized fatty acid amide, A sizing agent such as paraffin wax and alkenyl succinic acid, a starch, a polyamide polyamine epichlorohydrin, a paper strength enhancer such as polyacrylamide, a fixing agent such as a sulfuric acid band and a cationic polymer can be used. Moreover, you may add softening agents, such as surfactant. Furthermore, synthetic paper using synthetic pulp may be used in place of the natural pulp, or a mixture of natural pulp and synthetic pulp in an arbitrary ratio may be used. Among them, it is preferable to use hardwood pulp having short fibers and high smoothness. The water content of the pulp material to be used is preferably in the range of 200 to 500 ml (C.S.F), and more preferably in the range of 300 to 400 ml.

  The paper base material may contain other components such as a sizing agent, a softening agent, a paper strength agent, and a fixing agent. Examples of the sizing agent include rosin, paraffin wax, higher fatty acid salt, alkenyl succinate, fatty acid anhydride, styrene maleic anhydride copolymer, alkyl ketene dimer, epoxidized fatty acid amide, etc. Includes a reaction product of a maleic anhydride copolymer and a polyalkylene polyamine, a quaternary ammonium salt of a higher fatty acid, and the paper strength agent includes polyacrylamide, starch, polyvinyl alcohol, melamine formaldehyde condensate, gelatin In addition, examples of the fixing agent include a sulfuric acid band and a polyamide polyamine epichlorohydrin. In addition, dyes, fluorescent dyes, antistatic agents and the like can be added as necessary.

  The paper base is preferably subjected to activation treatment such as corona discharge treatment, flame treatment, glow discharge treatment, plasma treatment and the like before the formation of the pigment layer described above.

-Resin coated paper-
In the present invention, a resin-coated paper having a resin layer can also be used as the substrate. In this case, it is preferable to use the water-soluble resin described above as the binder for the undercoat layer in the present invention.

  As the paper substrate used for the resin-coated paper, the above-mentioned paper substrate can be used. Specifically, natural pulp paper composed mainly of normal natural pulp, mixed paper made of natural pulp and synthetic fibers, synthetic fiber paper composed mainly of synthetic fibers, synthetic resins such as polystyrene, polyethylene terephthalate, and polypropylene. Any of so-called synthetic papers in which the film is made pseudo-paper may be used, but natural pulp paper (the above base paper) is particularly preferably used. The base paper may be neutral paper (pH 5-9) or acidic paper, but neutral paper is preferred.

  In the base paper, fillers such as alkyl ketene dimer, clay, talc, calcium carbonate, urea resin fine particles, sizing agent such as rosin, higher fatty acid salt, paraffin wax, alkenyl succinic acid, paper strength enhancer such as polyacrylamide, A fixing agent such as a sulfuric acid band can be added. In addition, dyes, pigments, slime control agents, antifoaming agents, etc. are added as necessary. Moreover, a softening agent can be added as needed. With regard to the softening agent, for example, “New Paper Processing Handbook” (edited by Paper Medicine Time), pages 554 to 555 (issued in 1980), particularly those having a molecular weight of 200 or more are preferable. This softening agent is an amine salt or a quaternary ammonium salt having a hydrophobic group having 10 or more carbon atoms and self-fixing with cellulose. Specific examples of the softening agent include a reaction product of a maleic anhydride copolymer and a polyalkylene polyamine, a reaction product of a higher fatty acid and a polyalkylene polyamine, a reaction product of a urethane alcohol and an alkylating agent, Examples include quaternary ammonium salts of fatty acids, and particularly preferred are reaction products of maleic anhydride copolymers and polyalkylene polyamines and reaction products of urethane alcohols and alkylating agents.

The base paper is made by making a pulp slurry containing the above-described pulp and additives such as a filler, a sizing agent, a paper strength reinforcing agent, and a fixing agent added as necessary, using a paper machine such as a long net paper machine, Manufactured by drying and winding. Surface sizing can be performed either before or after this drying. For the surface sizing treatment, a film-forming polymer such as gelatin, starch, carboxymethylcellulose, polyacrylamide, polyvinyl alcohol, or a modified product of polyvinyl alcohol can be used. Examples of modified polyvinyl alcohol include carboxyl group-modified products, silanol-modified products, and copolymers with acrylamide. The coating amount of the film-forming polymer is usually adjusted to 0.1 to 5.0 g / m ² , preferably 0.5 to 2.0 g / m ² . Furthermore, an antistatic agent, a fluorescent brightening agent, a pigment, an antifoaming agent, and the like can be added to the film-forming polymer as necessary.

Moreover, a calendar process can be performed between winding after drying. When the surface treatment is performed after drying, the calender treatment can be carried out before or after the surface treatment, but it is preferable to carry out the calender treatment in the final finishing step after performing various treatments. As the metal roll and the elastic roll used for the calendering process, known ones used for the production of ordinary paper are used. The base paper is finally adjusted to a film thickness of about 50 to 250 μm by the calendar process described above. The density (unit mass) of the base paper is usually 0.8 to 1.3 g / m ² , preferably 1.0 to 1.2 g / m ² .

  Polyolefin is preferable as the resin constituting the coating resin layer of the paper substrate, but an electron beam cured product of an unsaturated organic compound that can be cured by electron beam irradiation is also effective. The resin layer may be a single layer or a multilayer. Moreover, in the case of a multilayer, lamination | stacking of a polyolefin layer, lamination | stacking of an electron beam cured material layer, lamination | stacking of a polyolefin layer and an electron beam cured material layer, etc. can be used.

  Among the above polyolefins, polyethylene is particularly preferable, but polyester is also effective. As the polyester, polyester of 2,6-naphthalenedicarboxylic acid (NDCA) and ethylene glycol (EG), polyester of NDCA, terephthalic acid and EG, polyethylene terephthalate, and the like are preferable.

  Examples of unsaturated organic compounds that can be cured by electron beam include (1) aliphatic, alicyclic, and aromatic acrylate compounds of 1 to 6-valent alcohols and polyalkylene glycols, and (2) aliphatics and fats. Cyclic and aromatic acrylate compounds obtained by adding alkylene oxide to 1 to 6 valent alcohols, (3) polyacryloylalkyl phosphate esters, (4) reaction products of carboxylic acid, polyol and acrylic acid (5) reaction product of isocyanate, polyol and acrylic acid, (6) reaction product of epoxy compound and acrylic acid, (7) reaction product of epoxy compound, polyol and acrylic acid, etc. .

  Specifically, polyoxyethylene epichlorohydrin modified bisphenol A diacrylate, dicyclohexyl acrylate, epichlorohydrin modified polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, hydroxybivalate ester neopentyl glycol diacrylate, nonylphenoxy polyethylene glycol acrylate , Ethylene oxide modified phenoxylated phosphate acrylate, ethylene oxide modified phthalate acrylate, polybutadiene acrylate, caprolactam modified tetrahydrofurfuryl acrylate, tris (acryloxyethyl) isocyanurate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetra Ak Rate, dipentaerythritol hexaacrylate, polyethylene glycol diacrylate, 1,4-butadiene diol diacrylate, can be used neopentyl glycol diacrylate, and neopentyl glycol-modified trimethylolpropane diacrylate. In the present invention, these compounds can be used alone or in combination of two or more thereof.

The base material used for the support of the present invention is not particularly limited. In addition to the above-mentioned paper base material and resin-coated paper, for example, polyesters such as polyethylene terephthalate (PET); polysulfone, polyphenylene oxide, polyimide , Polycarbonate, polyamide and the like.
Further, a highly glossy opaque base material can be used, and a read-only optical disk such as CD-ROM and DVD-ROM, a write-once optical disk such as CD-R and DVD-R, and a rewritable optical disk can also be used as the base material. it can.

  Although the thickness of the said base material is not specifically limited, Usually, it is about 100-250 micrometers, and 150-250 micrometers is preferable.

<Image recording material>
The image recording material of the present invention is constituted by providing various recording layers according to each application on the above-mentioned support of the present invention.

<Inkjet recording material>
Hereinafter, the image recording material of the present invention will be described focusing on an ink jet recording medium having an ink receiving layer formed on the support of the present invention as a recording layer for the purpose of receiving ink jet ink. It is not limited.

  An image recording material having an ink receiving layer that receives ink as an ink receiving layer in the present invention (hereinafter referred to as “inkjet recording medium”) is an undercoat layer (pigment layer and fluorescent enhancement layer) of the support of the present invention. Since the ink receiving layer is provided on the white layer), even when an absorbent support such as a paper base material is used, the surface on the side where the ink receiving layer is provided (hereinafter referred to as “image”). The recording surface is sometimes referred to as “recording surface.”), The whiteness of the recording surface is high, the flatness and the ink absorptivity are excellent, and it is possible to prevent the occurrence of image blurring (aging blur).

(Ink receiving layer)
The ink receiving layer preferably comprises at least a water-soluble resin, a cross-linking agent capable of cross-linking the water-soluble resin, fine particles, and a mordant, and further contains other components such as a mordant and a surfactant as necessary. Can be contained.

  The ink receiving layer has a porous structure by containing fine particles, thereby improving the ink absorption performance. In particular, if the solid content of the fine particle ink receiving layer is 50% by mass or more, more preferably more than 60% by mass, it becomes possible to obtain a more favorable porous structure, and the ink absorbability is further improved. be able to. Here, the solid content of the fine particle ink receiving layer is a content calculated based on components other than water in the composition constituting the ink receiving layer.

  The porous ink-receiving layer is a layer having a porosity of 50 to 75%, preferably 60 to 70%. When the porosity is in the range of 50 to 75%, the problem of powder falling due to insufficient binder does not occur. Further, in view of the quality of the ink jet recording medium, the thickness of the ink receiving layer is preferably 20 to 40 μm, and the 60 ° gloss is preferably 30 to 70%.

-Fine particles-
As the fine particles, both organic fine particles and inorganic fine particles can be used. Preferred examples of the organic fine particles include polymer fine particles obtained by, for example, emulsion polymerization, microemulsion polymerization, soap-free polymerization, seed polymerization, dispersion polymerization, suspension polymerization, and the like. Specifically, polyethylene, polypropylene, Examples thereof include powders such as polystyrene, polyacrylate, polyamide, silicone resin, phenol resin, natural polymer, latex or emulsion polymer fine particles, and the like.

Examples of the inorganic fine particles include silica fine particles, colloidal silica, titanium dioxide, barium sulfate, calcium silicate, zeolite, kaolinite, halloysite, mica, talc, calcium carbonate, magnesium carbonate, calcium sulfate, pseudoboehmite, and zinc oxide. Zinc hydroxide, alumina, aluminum silicate, calcium silicate, magnesium silicate, zirconium oxide, zirconium hydroxide, cerium oxide, lanthanum oxide, yttrium oxide and the like.
Among these, inorganic fine particles are preferable from the viewpoint of ink absorbability and image stability, and silica fine particles, colloidal silica, alumina fine particles, or pseudoboehmite are preferable from the viewpoint of forming a better porous structure.

  Among these, silica fine particles are generally roughly classified into wet method particles and dry method (vapor 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. A method of obtaining anhydrous silica by the (arc method) is the mainstream. The “gas phase method silica” means anhydrous silica fine particles obtained by the gas phase method. As the silica fine particles in the present invention, gas phase method silica fine particles are particularly preferable.

Vapor phase 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 silanol groups on the fine particle surface is high at 5 to 8 / nm ² , and the silica fine particles tend to aggregate (aggregate) easily. In the case of the method silica, the density of silanol groups on the surface of the fine particles is as small as ² to 3 / nm ² , resulting in sparse soft aggregation (flocculate), resulting in a structure with a high porosity. Presumed.

  Since the above-mentioned vapor phase silica has a particularly large specific surface area, the ink absorbency and retention efficiency are high, and the refractive index is low. Therefore, if the dispersion is carried out to an appropriate particle size, transparency can be imparted to the receiving layer. It is characterized by high color density and good color development. The transparency of the 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 50 nm or less, more preferably 20 nm or less, particularly preferably 10 nm or less, and most preferably 3 to 10 nm. Vapor phase silica is easy to adhere to each other due to hydrogen bonds with silanol groups, so that when the average primary particle size is 50 nm or less, it can form a structure with a large porosity, effectively improving ink absorption characteristics. Can be made.

  The vapor phase silica fine particles may be used in combination with the other fine particles described above. When the other fine particles and the vapor phase silica are used in combination, the content of the vapor phase silica in all the fine particles is preferably 30% by mass or more, and more preferably 50% by mass or more.

Furthermore, as the inorganic fine particles, alumina fine particles, alumina hydrate, a mixture or a composite thereof are also preferable. Of these, alumina hydrate is preferable because it absorbs and fixes ink well, and pseudoboehmite (Al ₂ O ₃ .nH ₂ O) is particularly preferable. The alumina hydrate can be used in various forms, but it is preferable to use sol boehmite as a raw material because a smooth layer can be easily obtained.

  Regarding the pore structure of the pseudoboehmite, the average pore radius is preferably 1 to 25 nm, and more preferably 2 to 10 nm. The pore volume is preferably 0.3 to 2.0 ml / g [cc / g], more preferably 0.5 to 1.50 ml / g [cc / g]. Here, the pore radius and the pore volume are measured by a nitrogen adsorption / desorption method, and can be measured using, for example, a gas adsorption / desorption analyzer (for example, trade name “Omni Soap 369” manufactured by Coulter).

  Among the alumina fine particles, vapor-phase method alumina fine particles are preferable because of their large specific surface area. The average primary particle diameter of the vapor phase alumina fine particles is preferably 50 nm or less, and more preferably 20 nm or less. Furthermore, colloidal silica having an average primary particle size of 50 nm or less is also preferable.

  The above-mentioned fine particles are, for example, JP-A-10-81064, JP-A-10-119423, JP-A-10-157277, JP-A-10-217601, JP-A-11-348409, JP-A-2001-138621, JP-A-2000-43401. 2000-212235, 2000-309157, 2001-96897, 2001-138627, JP-A-11-91242, 8-2087, 8-2090, 8-2091, The embodiments disclosed in JP-A-8-2093, JP-A-8-174992, JP-A-11-192777, JP-A-2001-301314 and the like can also be preferably used.

-Water-soluble resin-
Examples of the water-soluble resin used in the ink receiving layer include polyvinyl alcohol resins that are resins having a hydroxy group as a hydrophilic structural unit [polyvinyl alcohol (PVA), acetoacetyl-modified polyvinyl alcohol, cation-modified polyvinyl alcohol, anions. Modified polyvinyl alcohol, silanol-modified polyvinyl alcohol, polyvinyl acetal, etc.], cellulose resin [methyl cellulose (MC), ethyl cellulose (EC), hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), hydroxypropyl cellulose (HPC), hydroxyethyl methyl cellulose , Hydroxypropyl methylcellulose, etc.], chitins, chitosans, starch, resins having an ether bond [polyethylene Oxide (PEO), polypropylene oxide (PPO), polyethylene glycol (PEG), polyvinyl ether (PVE), etc.], resins having a carbamoyl group [polyacrylamide (PAAM), polyvinylpyrrolidone (PVP), polyacrylic acid hydrazide, etc.], etc. Is mentioned. Moreover, the polyacrylic acid salt which has a carboxyl group as a dissociable group, maleic acid resin, alginate, gelatins, etc. can be mentioned. The water-soluble resin can be used alone or in combination of two or more.

Among the above, polyvinyl alcohol resin is particularly preferable. Examples of the polyvinyl alcohol include Japanese Patent Publication No. 4-52786, Japanese Patent Publication No. 5-67432, Japanese Patent Publication No. 7-29479, Japanese Patent No. 2537827, Japanese Patent Publication No. 7-57553, Japanese Patent No. 2502998, and Japanese Patent No. 3053231. JP-A-63-176173, JP-A-2604367, JP-A-7-276787, JP-A-9-207425, JP-A-11-58941, JP-A-2000-135858, JP-A-2001-205924, JP 2001-287444, JP 62-278080, JP 9-39373, JP 2750433, JP 2000-18801, JP 2001-213045, JP 2001-328345, JP 8 -324105, JP-A-11-348417, etc. . Examples of the water-soluble resin other than the polyvinyl alcohol resin include compounds described in “0011” to “0014” of JP-A No. 11-165461.
Said water-soluble resin may be used independently and may use 2 or more types together.

  As content of the said water-soluble resin in the said ink receiving layer, 9-40 mass% is preferable with respect to the total solid content mass of an ink receiving layer, and 12-33 mass% is still more preferable. The water-soluble resin and the fine particles described above may be a single material or a mixed system of a plurality of materials.

  Further, from the viewpoint of ensuring the transparency of the ink receiving layer, the type of the water-soluble resin combined with the fine particles, particularly the silica fine particles, is important. When the above-mentioned gas phase method silica is used, it is preferable to combine a polyvinyl alcohol resin as the water-soluble resin, and among them, a polyvinyl alcohol resin having a saponification degree of 70 to 100% is preferable, and a saponification degree of 80 to 99.5%. The polyvinyl alcohol resin is particularly preferable.

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

  Moreover, you may use together said other water-soluble resin for polyvinyl alcohol-type resin. When the other water-soluble resin and the polyvinyl alcohol resin are used in combination, the amount of the polyvinyl alcohol resin is preferably 50% by mass or more, more preferably 70% by mass or more of the total water-soluble resin.

<Content ratio of fine particles and water-soluble resin>
The mass ratio [PB ratio; = x / y] of the mass (x) of the fine particles and the mass (y) of the water-soluble resin greatly affects the film structure and film strength of the ink receiving layer. That is, as the mass ratio (PB ratio) increases, the porosity, pore volume, and surface area (per unit mass) increase, but the density and strength tend to decrease.
As the PB ratio (x / y) in the ink receiving layer, the decrease in film strength and cracking at the time of drying caused by the PB ratio being too large are prevented, and the PB ratio is too small. From the viewpoint of preventing the ink absorbability from being lowered due to the void being easily blocked by the resin and decreasing the porosity, 1.5 to 10 is preferable.

  In addition, 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 and is cut into a sheet shape. In addition, the ink receiving layer needs to have sufficient film strength from the viewpoint of preventing the ink receiving layer from cracking or peeling. In consideration of these, the PB ratio is more preferably 5 or less, and more preferably 2 or more from the viewpoint of ensuring high-speed ink absorbability in an inkjet printer.

For example, a coating solution in which gas phase method silica fine particles 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 (x / y) of 2 to 5 is applied on a support and dried. In this case, a three-dimensional network structure in which the secondary particles of silica fine particles are network chains is formed, the average pore diameter is 25 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.

-Crosslinking agent-
The ink receiving layer in the present invention is a porous layer in which a layer containing inorganic fine particles and a water-soluble resin further contains a cross-linking agent capable of cross-linking the water-soluble resin, and is cured by a cross-linking reaction between the cross-linking agent and the water-soluble resin. The aspect which is a quality layer is preferable.

As the cross-linking agent, a suitable one may be selected as appropriate in relation to the water-soluble resin contained in the ink receiving layer, and among them, boric acid or a boron compound is preferable in that the cross-linking reaction is rapid. Examples of the boron compound include borax, borate (for example, orthoborate, InBO ₃ , ScBO ₃ , YBO ₃ , LaBO ₃ , Mg ₃ (BO ₃ ) ₂ , Co ₃ (BO ₃ ) ₂ , diborate). (For example, Mg ₂ B ₂ O ₅ , Co ₂ B ₂ O ₅ ), metaborate (for example, LiBO ₂ , Ca (BO ₂ ) ₂ , NaBO ₂ , KBO ₂ ), tetraborate (for example, 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.

  Of these, borax, boric acid and borates are preferable, and boric acid is more preferable, and it is particularly preferable to use these in combination with polyvinyl alcohol, which is a water-soluble resin, from the viewpoint of causing a rapid crosslinking reaction.

  The crosslinking agent is preferably contained in an amount of 0.05 to 0.50 parts by mass, and more preferably 0.08 to 0.30 parts by mass with respect to 1 part by mass of the water-soluble resin. When the content of the crosslinking agent is within the above range, the water-soluble resin can be crosslinked to effectively prevent cracking and the like.

  In addition, when gelatin is used as the water-soluble resin, boron and the following compounds other than boron compounds can also be used as a crosslinking agent. 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;

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; Titanium lactate, aluminum sulfate, chromium alum, potash alum, metal-containing compounds such as zirconyl acetate and chromium acetate, polyamine compounds such as tetraethylenepentamine, and hydrazide compounds such as adipic acid dihydrazide A small molecule or polymer or the like containing an oxazoline group two or more. The above crosslinking agents may be used singly or in combination of two or more.

  The cross-linking agent is used in the ink-receiving layer coating liquid and / or the adjacent layer of the ink-receiving layer when applying a coating liquid for forming an ink-receiving layer (hereinafter sometimes referred to as “ink-receiving layer coating liquid”). For the ink-receiving layer containing no cross-linking agent, the ink-receiving layer-coating liquid may be applied to a support on which a coating liquid containing a cross-linking agent has been previously applied. The cross-linking agent can be supplied to the ink receiving layer by, for example, overcoating the cross-linking agent solution after applying and drying the coating liquid.

  For example, the crosslinking agent can be suitably applied as follows. Here, a boron compound will be described as an example. That is, when the ink receiving layer is a layer obtained by crosslinking and curing the coating layer coated with the coating liquid for the ink receiving layer (first liquid), the crosslinking curing is (1) forming the coating layer by coating the coating liquid. At the same time, (2) a basic solution having a pH of 7.1 or higher during the dry coating of the coating layer formed by coating the coating solution and before the coating layer exhibits reduced drying. It can be carried out by applying (second liquid) to the coating layer. The boron compound which is a cross-linking agent may be contained in either the first liquid or the second liquid, and may be contained in both the first liquid and the second liquid. A specific method will be described later.

-Mordant-
In the present invention, a mordant is preferably contained in the ink receiving layer in order to further improve the water resistance and aging resistance of the formed image. As the mordant, any of an organic mordant such as a cationic polymer (cationic mordant) and an inorganic mordant such as a water-soluble metal compound can be used. Of these, organic mordants are preferable, and cationic mordants are particularly preferable.

  The presence of the mordant in at least the upper layer of the ink receiving layer allows interaction with a liquid ink having an anionic dye as a coloring material, thereby stabilizing the coloring material and preventing water resistance and aging resistance. Further improvements can be made.

  In this case, it may be contained in any of the ink receiving layer coating liquid (first liquid) and the basic solution (second liquid) when forming the ink receiving layer, but inorganic fine particles (particularly gas phase method silica). It is preferable to contain and use in the 2nd liquid used as a liquid different from the liquid containing. That is, when the mordant is added directly to the ink receiving layer coating solution, aggregation may occur in the presence of an anion charge-containing silica vapor, but the mordant containing solution and the ink receiving layer coating solution are respectively If the method of independently preparing and coating each is employed, it is not necessary to consider the aggregation of inorganic fine particles, and the range of mordant selection is expanded.

As the cationic mordant, a polymer mordant having a primary to tertiary amino group or a quaternary ammonium base as a cationic functional group is preferably used, but a cationic non-polymer mordant is also used. be able to.
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 (hereinafter referred to as “mordant monomer”), the mordant monomer, Those obtained as copolymers or condensation polymers with other monomers (hereinafter referred to as “non-mordant polymer”) are preferred. 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 for 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, allylamine, diallylamine, derivatives thereof, salts and the like can also be used. Examples of such compounds include allylamine, allylamine hydrochloride, allylamine acetate, allylamine sulfate, diallylamine, diallylamine hydrochloride, diallylamine acetate, diallylamine sulfate, diallylmethylamine and salts thereof (for example, Hydrochloride, acetate, sulfate, etc.), diallylethylamine and salts thereof (for example, hydrochloride, acetate, sulfate, etc.), diallyldimethylammonium salt (chloride, acetic acid as counter anions of the salt) Ion sulfate, etc.). In addition, since these allylamines and diallylamine derivatives are inferior in polymerizability in the form of amine, it is a general production method to polymerize in the form of a salt and desalting as required.
Further, it is also possible to use a polymerization unit such as N-vinylacetamide or N-vinylformamide, which is converted into a vinylamine unit by hydrolysis after polymerization, and a salt thereof.

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.
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, 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 monomers can be used alone or in combination of two or more.

Further, as a cationic mordant, polydiallyldimethylammonium chloride, polymethacryloyloxyethyl-β-hydroxyethyldimethylammonium chloride, polyethyleneimine, polyallylamine and derivatives thereof, polyamide-polyamine resin, cationized starch, dicyandiamide formalin condensate, dimethyl Addition of 2-hydroxypropylammonium salt polymer, polyamidine, polyvinylamine, dicyandiamide-formalin polycondensate, dicyanamide-cachinic resin represented by dicyanamide-diethylenetriamine polycondensate, polyamine-type katine resin, epichlorohydrin-dimethylamine polymer, dimethyldiallylammonium phosphorus chloride -SO ₂ copolymers, diallylamine salt -SO ₂ copolymer, Quaternary ammonium base-substituted alkyl group having an ester moiety (meth) acrylate-containing polymers, styryl polymers having a quaternary ammonium base-substituted alkyl group may be mentioned as being also preferred.

  Specific examples of the cationic mordant include JP-A Nos. 48-28325, 54-74430, 54-124726, 55-22766, 55-142339, 60-23850, and the like. 60-23851, 60-23852, 60-23853, 60-57836, 60-60643, 60-118834, 60-122940, 60-122941, 60- Nos. 122942, 60-235134, JP-A-1-161236, U.S. Pat.Nos. 2,484,430, 2,548,564, 3,148,061, 3,309,690, 4,115,124, 4,124,386, 4,193,800, 4,227,8353 Nos. 4282305 and 4450224, JP No. 161236, No. 10-81064, No. 10-119423, No. 10-157277, No. 10-217601, No. 11-348409, JP-A No. 2001-138621, No. 2000-43401, No. 2000- 211235, 2000-309157, 2001-96897, 2001-138627, JP-A-11-91242, 8-2087, 8-2090, 8-2091, 8-2093 No. 8-1744992, No. 11-192777, JP-A No. 2001-301314, JP-B-5-35162, No. 5-35163, No. 5-35164, No. 5-88846, JP-A No. 7-8846 No. 118333, Japanese Patent Laid-Open No. 2000-344990, etc., Japanese Patent Nos. 2648847, 266167 Include those such as described in the specification of the issue, and the like. Among them, polyallylamine and derivatives thereof are preferable, and diallyldialkyl cationic polymers are preferable in terms of structure.

  As the polyallylamine or a derivative thereof, various known allylamine polymers and derivatives thereof can be used. Examples of such derivatives include salts of polyallylamine and acids (acids include inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid, methanesulfonic acid, toluenesulfonic acid, acetic acid, propionic acid, cinnamic acid, (meth) An organic acid such as acrylic acid, or a combination thereof, a salt of only a part of allylamine), a derivative of polyallylamine by a polymer reaction, a copolymer of polyallylamine and another copolymerizable monomer Specific examples of the monomer include (meth) acrylic acid esters, styrenes, (meth) acrylamides, acrylonitrile, vinyl esters and the like.

  Specific examples of polyallylamine and derivatives thereof include JP-B-62-31722, JP-B-2-14364, JP-B-63-43402, 63-43403, 63-45721, 63-29881, Japanese Patent Publication No. 1-26362, No. 2-56365, No. 2-57084, No. 4-41686, No. 6-2780, No. 6-45649, No. 6-15592, No. 4-68622, Patents No. 3199227, No. 3008369, JP-A No. 10-330427, No. 11-21321, JP-A No. 2000-281728, No. 2001-106736, JP-A No. 62-256801, JP-A No. 7-173286, 7-213897, 9-235318, 9-302026, 11-21321, WO99 / 2190 No., No. WO99 / nineteen thousand three hundred and seventy-two, JP-A-5-140213, compounds described in JP Kohyo No. 11-506488, and the like.

Among the above-mentioned cationic mordants, diallyl dialkyl cationic polymers are preferable, and diallyl dimethyl cationic polymers are particularly preferable. The cationic mordant is preferably a cationic polymer having a weight average molecular weight of 60000 or less, particularly 40000 or less, from the viewpoint of dispersibility, particularly prevention of thickening.
The cationic mordant is also useful as the fine particle dispersant described above.

  In addition, when a cationic mordant is added to the coating solution for the ink receiving layer, the sulfate ion concentration in the coating solution is preferably 1.5% by mass or less from the viewpoint of preventing thickening of the solution. This sulfate ion is contained in the polymerization initiator at the time of production of the cationic polymer, and since it remains in the polymer, the cationic mordant is formed using a polymerization initiator that does not emit sulfate ion. Is desirable.

  Examples of the inorganic mordant include polyvalent water-soluble metal salts and hydrophobic metal salt compounds. Specific examples of the inorganic mordant include, for example, magnesium, aluminum, calcium, scandium, titanium, vanadium, manganese, iron, nickel, copper, zinc, gallium, germanium, strontium, yttrium, zirconium, molybdenum, indium, barium, Examples include salts or complexes of metals selected from lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, dysprosium, erbium, ytterbium, hafnium, tungsten, bismuth.

  Specific examples of the inorganic mordant include calcium acetate, calcium chloride, calcium formate, calcium sulfate, barium acetate, barium sulfate, barium phosphate, manganese chloride, manganese acetate, manganese formate dihydrate, manganese ammonium sulfate hexahydrate. , Cupric chloride, ammonium copper (II) chloride dihydrate, copper sulfate, cobalt chloride, cobalt thiocyanate, cobalt sulfate, nickel sulfate hexahydrate, nickel chloride hexahydrate, nickel acetate tetrahydrate , Nickel ammonium sulfate hexahydrate, nickel amidosulfate tetrahydrate, aluminum sulfate, aluminum alum, basic polyaluminum hydroxide, aluminum sulfite, aluminum thiosulfate, polyaluminum chloride, aluminum nitrate nonahydrate, chloride Aluminum hexahydrate, ferrous bromide, ferrous chloride , Ferric chloride, ferrous sulfate, ferric sulfate, zinc phenolsulfonate, zinc bromide, zinc chloride, zinc nitrate hexahydrate, zinc sulfate, titanium tetrachloride, tetraisopropyl titanate, titanium acetylacetonate , Titanium lactate, Zirconium acetylacetonate, Zirconyl acetate, Zirconyl sulfate, Ammonium zirconium carbonate, Zirconyl stearate, Zirconyl octylate, Zirconyl nitrate, Zirconium oxychloride, Hydroxy zirconium chloride, Chromium acetate, Chromium sulfate, Magnesium sulfate, Magnesium chloride Hydrate, magnesium citrate nonahydrate, sodium phosphotungstate, sodium tungsten citrate, 12 tungstophosphoric acid n hydrate, 12 tungstosilicic acid 26 hydrate, molybdenum chloride, 12 molybdophosphoric acid n Japanese, gallium nitrate, germanium nitrate, strontium nitrate, yttrium acetate, yttrium chloride, yttrium nitrate, indium nitrate, lanthanum nitrate, lanthanum chloride, lanthanum acetate, lanthanum benzoate, cerium chloride, cerium sulfate, cerium sulfate, praseodymium nitrate, Examples thereof include neodymium nitrate, samarium nitrate, europium nitrate, gadolinium nitrate, dysprosium nitrate, erbium nitrate, ytterbium nitrate, hafnium chloride, and bismuth nitrate.

Among the inorganic mordants, aluminum-containing compounds, titanium-containing compounds, zirconium-containing compounds, and group IIIB series metal compounds (salts or complexes) are preferable.
Amount of the mordant in the ink-receiving layer is preferably 0.01-5 g / m ^2, more preferably 0.1 to 3 g / m ^2.

-Other ingredients-
In the ink-receiving layer of the present invention, various known additives such as acids, ultraviolet absorbers, antioxidants, fluorescent brighteners, monomers, polymerization initiators, polymerization inhibitors, and blur prevention are optionally added. Agents, preservatives, viscosity stabilizers, antifoaming agents, surfactants, antistatic agents, matting agents, anti-curling agents, water-proofing agents, and the like.

  The ink receiving layer in the invention may contain an acid. By adjusting the surface pH of the ink receiving layer to 3 to 8, preferably 3.5 to 6.0 by adding the above acid, yellowing resistance of the white background can be improved. The surface pH can be measured by the A method (coating method) among the surface PH measurements determined by the Japan Paper Pulp Technology Association (J.TAPPI). For example, Kyoritsu Co., Ltd., which corresponds to the above A method, is available. This can be done using a PH measurement set for paper “Type MPC” manufactured by RIKEN.

  Specific examples of the acid include formic acid, acetic acid, glycolic acid, oxalic acid, propionic acid, malonic acid, succinic acid, adipic acid, maleic acid, malic acid, tartaric acid, citric acid, benzoic acid, phthalic acid, isophthalic acid Acid, glutaric acid, gluconic acid, lactic acid, aspartic acid, glutamic acid, salicylic acid, salicylic acid metal salts (Zn, Al, Ca, Mg, etc.), methanesulfonic acid, itaconic acid, benzenesulfonic acid, toluenesulfonic acid, trifluoromethane Sulfonic acid, styrenesulfonic acid, trifluoroacetic acid, barbituric acid, acrylic acid, methacrylic acid, cinnamic acid, 4-hydroxybenzoic acid, aminobenzoic acid, naphthalene disulfonic acid, hydroxybenzenesulfonic acid, toluenesulfinic acid, benzenesulfinic acid , Sulfanilic acid, sulfamic acid, α Resorcinic acid, β-resorcinic acid, γ-resorcinic acid, gallic acid, phloroglicin, sulfosalicylic acid, ascorbic acid, erythorbic acid, bisphenolic acid, hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, boric acid, boronic acid, etc. Can be mentioned. The amount of these acids added may be determined so that the surface PH of the ink receiving layer is 3-8.

  The acid may be a metal salt (eg, sodium, potassium, calcium, cesium, zinc, copper, iron, aluminum, zirconium, lanthanum, yttrium, magnesium, strontium, cerium, etc.) or an amine salt (eg, ammonia, triethylamine, (Tributylamine, piperazine, 2-methylpiperazine, polyallylamine, etc.).

In the present invention, it is preferable that the ink receiving layer contains a preservability improving agent such as an ultraviolet absorbent, an antioxidant, or a bleeding inhibitor.
These ultraviolet absorbers, antioxidants, and bleeding inhibitors include alkylated phenolic compounds (including hindered phenolic compounds), alkylthiomethylphenolic compounds, hydroquinone compounds, alkylated hydroquinone compounds, tocopherol compounds, thiodiphenyl ether compounds. Compounds having two or more thioether bonds, bisphenolic compounds, O-, N- and S-benzyl compounds, hydroxybenzyl compounds, triazine compounds, phosphonate compounds, acylaminophenolic compounds, ester compounds, amide compounds, ascorbic acid , Amine antioxidants, 2- (2-hydroxyphenyl) benzotriazole compounds, 2-hydroxybenzophenone compounds, acrylates, water-soluble or hydrophobic metal salts, organometallic compounds , Metal complexes, hindered amine compounds (including TEMPO compounds), 2- (2-hydroxyphenyl) 1,3,5, -triazine compounds, metal deactivators, phosphite compounds, phosphonite compounds, hydroxyamine compounds, nitrone compounds , Peroxide scavenger, polyamide stabilizer, polyether compound, basic auxiliary stabilizer, nucleating agent, benzofuranone compound, indolinone compound, phosphine compound, polyamine compound, thiourea compound, urea compound, hydrazide compound, amidine compound, sugar compound , Hydroxybenzoic acid compounds, dihydroxybenzoic acid compounds, trihydroxybenzoic acid compounds and the like.

  Among these, alkylated phenolic compounds, compounds having two or more thioether bonds, bisphenolic compounds, ascorbic acid, amine-based antioxidants, water-soluble or hydrophobic metal salts, organometallic compounds, metal complexes, hindered amines It is preferable to contain at least one of a compound, a polyamine compound, a thiourea compound, a hydrazide compound, a hydroxybenzoic acid compound, a dihydroxybenzoic acid compound, and a trihydroxybenzoic acid compound.

  Specific examples of the compound include Japanese Patent Application No. 2002-13005, Japanese Patent Application Laid-Open No. 10-182621, Japanese Patent Application Laid-Open No. 2001-260519, Japanese Patent Application No. 4-34953, Japanese Patent Application No. 4-34513, Japanese Patent Application Laid-Open No. 11-170686, No. 4-34512, EP 1138509, JP-A-60-67190, JP-A-7-276808, JP-A-2001-94829, JP-A-47-10537, JP-A-58-111942, and JP-A-58-212844. 59-19945, 59-46646, 59-109055, 63-53544, JP 36-10466, 42-26187, 48-30492, 48-31255, 48-41572, 48-54965, 50-10726, U.S. Pat.No. 2,719,086, 3 No. 707,375, the 3,754,919 Patent, the 4,220,711 Patent,

Japanese Patent Publication Nos. 45-4699, 54-5324, European Published Patent Nos. 223739, 309401, 309402, 3105301, 310552, 457416, German Published Patent No. 3435443, Kaisho 54-48535, 60-107384, 60-107383, 60-125470, 60-125471, 60-125472, 60-287485, 60-287486, 60-287487, 60-287488, 61-160287, 61-18854, 61-2111079, 62-146678, 62-146680, 62-146679, 62- No. 282885, No. 62-262047, No. 63-051174, Nos. 63-89877, 63-88380 same issue, same 66-88381 JP, same 63-113536 issue,

63-163351, 63-203372, 63-224989, 63-251282, 63-267594, 63-182484, JP-A-1-239282, JP-A-2-262654, 2-71262, 3-121449, 4-291865, 4-291684, 5-611166, 5-119449, 5-188687, 5-188686, 5 No. 110490, No. 5-110437, No. 5-170361, No. 48-43295, No. 48-33212, US Pat. Nos. 4,814,262, No. 4,980,275, and the like. It is done.

Other additives may be used alone or in combination of two or more. Other additives may be added after being water-solubilized, dispersed, polymer-dispersed, emulsified or formed into oil droplets, or may be encapsulated in microcapsules. Moreover, as addition amount in the case of adding another additive, 0.01-10 g / m < ² > is preferable.

  In order to improve the dispersibility of the fine particles, the surface of the fine particles may be treated with a silane coupling agent. As the silane coupling agent, an organic functional group (for example, vinyl And a group having an amino group (primary to tertiary amino group, quaternary ammonium base), an epoxy group, a mercapto group, a chloro group, an alkyl group, a phenyl group, an ester group, or the like can be preferably used.

  The ink receiving layer (ink receiving layer coating solution) in the present invention preferably contains a surfactant. The surfactant can be appropriately selected from anionic, cationic, nonionic, amphoteric, fluorine and silicone surfactants. Moreover, surfactant may be used individually by 1 type, or may use 2 or more types together.

Examples of the anionic surfactant include fatty acid salts (eg, sodium stearate, potassium oleate), alkyl sulfate esters (eg, sodium lauryl sulfate, triethanolamine lauryl sulfate), and sulfonates (eg, sodium dodecylbenzene sulfonate). 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 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, 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 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, propylene oxide adducts, etc. of the diols). Alkylene alkyl ethers are preferable. The nonionic surfactant may be contained in either the ink receiving layer coating solution (first solution) or the basic solution (second solution), and may be used alone or in combination of two or more. You can also.

  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. These can be used alone or in combination of two or more.

  Examples of the fluorosurfactant include compounds derived via an intermediate having a perfluoroalkyl group using a method such as electrolytic fluorination, telomerization, and 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% by mass, and more preferably 0.01 to 1.0% by mass. Further, when coating is performed using two or more liquids as the ink receiving layer coating liquid, it is preferable to add a surfactant to each coating liquid.

In the present invention, the ink receiving layer preferably contains a high boiling point organic solvent for curling prevention. The high-boiling organic solvent is an organic compound having a boiling point of 150 ° C. or higher at normal pressure, and is a water-soluble or hydrophobic compound. These may be liquid or solid at room temperature, and may be low molecules or polymers.
Specifically, aromatic carboxylic acid esters (for example, dibutyl phthalate, diphenyl phthalate, phenyl benzoate, etc.), aliphatic carboxylic acid esters (for example, dioctyl adipate, dibutyl sebacate, methyl stearate, dibutyl maleate) , Dibutyl fumarate, triethyl acetyl citrate, etc.), phosphate esters (eg, trioctyl phosphate, tricresyl phosphate, etc.), epoxies (eg, epoxidized soybean oil, epoxidized fatty acid methyl, etc.), alcohols (eg, stearyl) Alcohol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, glycerol, diethylene glycol monobutyl ether (DEGMBE), triethylene glycol monobutyl ether, glycerol Methyl ether, 1,2,3-butanetriol, 1,2,4-butanetriol, 1,2,4-pentanetriol, 1,2,6-hexanetriol, thiodiglycol, triethanolamine, polyethylene glycol, etc. ), Vegetable oils (eg, soybean oil, sunflower oil, etc.) and higher aliphatic carboxylic acids (eg, linoleic acid, oleic acid, etc.).

(Inkjet recording medium manufacturing method)
In the ink jet recording medium of the present invention, first, an ink receiving layer constituting the medium is coated with a coating liquid (first liquid) and a basic solution (second liquid) for forming an ink receiving layer containing at least fine particles and a water-soluble resin. ) And a coating agent (first liquid) is applied onto the undercoat layer of the present invention to form a coating layer, and (1) the coating liquid is applied. (2) either during the drying of the coating layer formed by coating the coating liquid (first liquid) and before the coating layer exhibits reduced rate drying. Sometimes, the basic solution (second liquid) having a pH of 8 or more is applied to the coating layer, and the coating layer is formed by a method of crosslinking and curing (Wet on Wet method), and is prepared by coating and drying. can do.

  Thus, by adding the mordant to the second liquid, for example, (1) a coating layer (first liquid) containing fine particles, a water-soluble resin, and a crosslinking agent is formed, and the mordant-containing solution (first liquid (2 liquid) is applied by any method, (2) a coating liquid containing fine particles and a water-soluble resin (first liquid) and a mordant-containing solution (second liquid) are applied in multiple layers. Can do. For this reason, since a large amount of mordant can be present near the surface of the ink receiving layer, the coloring material of the ink is sufficiently mordanted, and the water resistance of recorded characters and images can be improved.

  Further, since a large amount of mordant is present in a predetermined portion of the ink receiving layer, it is possible to improve the color density, ink bleeding with time, gloss of the printed part, water resistance of printed characters and images, and ozone resistance. Part of the mordant may be contained in the first liquid. In that case, the mordants of the first liquid and the second liquid may be the same or different.

  An example of preparing a coating solution using the first solution, for example, vapor phase method silica, polyvinyl alcohol, a boron compound, and a cationic polymer will be described below. That is, gas phase method silica is added to water together with a cationic polymer (for example, 10 to 20% by mass), and using a high-speed rotating wet colloid mill (for example, trade name: CLEARMIX, manufactured by M Technique Co., Ltd.) After being dispersed for 20 minutes (preferably 10 to 30 minutes) under high speed rotation conditions of 10,000 rpm (preferably 5000 to 20000 rpm) to form a fine particle dispersion, a boron compound and an aqueous polyvinyl alcohol solution (for example, 1 / of silica amount) are further added. To a mass of about 3) and further dispersing under the same conditions as described above. The obtained coating liquid is a uniform sol, and a porous ink receiving layer having a three-dimensional network structure can be formed by coating and forming this on a support by the following coating method. If necessary, a pH adjuster, other dispersants, surfactants, antifoaming agents, antistatic agents, and the like can be further added to the first liquid.

  In preparing the first liquid and the second liquid, water, an organic solvent, or a mixed solvent thereof can be used as a solvent. Examples of the organic solvent include alcohols such as methanol, ethanol, n-propanol, i-propanol and methoxypropanol, ketones such as acetone and methyl ethyl ketone, tetrahydrofuran, acetonitrile, ethyl acetate and toluene.

  The first liquid (ink receiving layer coating liquid) is applied by, for example, 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. Can be done.

  The second liquid (basic solution) is applied to the coating layer at the same time as or after the coating of the first liquid (ink receiving layer coating liquid). You may give before it comes to show decremental drying. That is, after the application liquid for the ink-receiving layer is applied, the basic solution is preferably introduced while the applied layer exhibits constant rate drying. This second liquid may contain a mordant.

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

  As described above, after the application of the first liquid, the coating layer is dried until the coating layer exhibits reduced-rate drying. This drying is generally performed at 40 to 180 ° C. for 0.5 to 10 minutes (preferably, 0.00. 5-5 minutes). The drying time naturally varies depending on the coating amount, but the above range is usually appropriate.

  As a method of applying the second liquid before the reduced rate drying is exhibited, (1) a method of further applying the second liquid onto the coating layer, (2) a method of spraying by a method such as spraying, (3 ) A method of immersing the support on which the coating layer is formed in the second liquid.

  In the above method (1), as the coating method for coating the second liquid, for example, curtain flow coater, extrusion die coater, air doctor coater, bread coater, rod coater, knife coater, squeeze coater, reverse roll coater, bar A known coating method such as a coater can be used. However, it is preferable to use a method in which the coater does not directly contact the already formed first coating layer, such as an extrusion die coater, a curtain flow coater, a bar coater or the like.

The application amount of the second liquid, 5 to 50 g / m ² is generally, 10 to 30 g / m ² is preferred.

  After application of the second liquid, it is generally heated at 40 to 180 ° C. for 0.5 to 30 minutes, and dried and cured. Especially, it is preferable to heat at 40-150 degreeC for 1 to 20 minutes. For example, when the crosslinking agent contained in the first liquid is boric acid or a boron compound (borax or the like), it is preferable to perform heating at 60 to 100 ° C. for 5 to 20 minutes.

  In addition, when the basic solution (second liquid) is applied simultaneously with the application of the ink-receiving layer coating liquid (first liquid), the first liquid and the second liquid are in contact with the support. Thus, the ink receiving layer can be formed by simultaneous application (multilayer application) on the support, followed by drying and curing.

  The simultaneous coating (multilayer coating) can be performed by a coating method using, for example, an extrusion die coater or a curtain flow coater. After the simultaneous coating, the formed coating layer is dried. In this case, the drying is generally performed by heating the coating 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.

  When the above simultaneous coating (multilayer coating) is performed by, for example, an extrusion die coater, the two types of liquid discharged simultaneously are in the vicinity of the discharge port of the extrusion die coater, that is, before moving onto the support. In that state, it is coated on the support in multiple layers. Since the two-layer coating liquid layered before coating is likely to cause a cross-linking 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. As a result, thickening is likely to occur, which may hinder the application operation. Therefore, at the time of simultaneous application as described above, it is preferable that simultaneous triple layer application is performed with the barrier liquid (intermediate liquid) interposed between the two liquids together with the application of the first liquid and the second liquid.

  The barrier layer solution can be selected without particular limitation. For example, an aqueous solution containing a trace amount of water-soluble resin, water, and the like can be given. The water-soluble resin is used in consideration of applicability for the purpose of a thickener and the like. For example, a cellulose resin (for example, hydroxypropylmethylcellulose, methylcellulose, hydroxyethylmethylcellulose) And polymers such as polyvinylpyrrolidone and gelatin. The barrier layer solution may contain the above mordant.

  The ink receiving layer uses, for example, a soft calender, a super calender, a gloss calender, etc., and improves the surface smoothness, glossiness, transparency and coating strength by applying a calender treatment through the roll nip under heat and pressure. It is possible.

  As roll temperature in performing the said calendar process, 30-150 degreeC is preferable and 40-100 degreeC is still 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 still 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.

  Further, the pore diameter of the ink receiving layer is preferably 0.005 to 0.030 [mu] m, more preferably 0.01 to 0.025 [mu] m 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.).

<Image receiving material for digital electrophotography>
In the case where a toner receiving layer is formed as the recording layer in the present invention, the image forming material in the present invention can be used as an image receiving material for digital electrophotography.
The image receiving material for digital electrophotography has at least one toner receiving layer on the undercoat layer of the support of the present invention, and other layers appropriately selected as necessary, for example, a surface protective layer , Intermediate layer, undercoat layer, cushion layer, charge control (prevention) layer, reflection layer, tint preparation layer, storage stability improving layer, adhesion prevention layer, anti-curl layer, smoothing layer and the like. Each of these layers may have a single layer structure or a laminated structure.

(Toner receiving layer)
The toner receiving layer is a toner receiving layer for receiving color or black toner and forming an image. The toner receiving layer has a function of receiving toner that forms an image from a developing drum or an intermediate transfer member by (electrostatic) electricity, pressure, or the like in a transfer process, and fixing it by heat, pressure, or the like in a fixing process. Have Further, the toner receiving layer contains at least a thermoplastic resin and, if necessary, other components.

-Thermoplastic resin-
The thermoplastic resin is not particularly limited as long as it can be deformed under temperature conditions such as fixing and can receive toner, and a known thermoplastic resin can be appropriately selected and used. As the thermoplastic resin, those which can satisfy the properties of the toner receiving layer in a state where the toner receiving layer is formed are preferable.

  In addition to the thermoplastic resin, the toner-receiving layer includes a colorant such as a pigment / dye, a plasticizer, a release agent, a slip agent, a matting agent, a filler, a crosslinking agent, a charge control agent, an emulsion, A dispersion etc. can be contained.

  The thermoplastic resin content in the toner receiving layer is preferably 50% by mass or more, and more preferably 50 to 90% by mass.

<Silver photographic material>
The silver salt photographic light-sensitive material has a structure in which a silver salt photographic light-sensitive layer that develops color at least in YMC is provided as a recording layer on the support of the present invention. Examples of the silver salt photographic light-sensitive material include, for example, passing a silver halide photographic sheet subjected to printing exposure while immersing it in a plurality of processing tanks, and performing color development, bleach-fixing, washing with water, and drying to obtain an image. And materials used in the silver halide photographic system for obtaining the above.

<Thermal recording material>
The heat-sensitive recording material has, for example, a structure in which at least a heat-sensitive coloring layer is provided as a recording layer in the present invention on a support of the present invention, and an image is formed by repeated heating with a heat-sensitive head and fixing with ultraviolet rays. And a thermosensitive recording material used in the thermoautochrome method (TA method).

<Sublimation transfer image receiving material>
The sublimation transfer image receiving material has a structure in which an image receiving layer for receiving a heat diffusible dye (sublimation dye) is provided as a recording layer in the invention on the support of the invention. Examples of the sublimation transfer image receiving material include materials used in a sublimation transfer system in which a transfer material having an ink layer is heated by a thermal head to transfer a heat diffusible dye contained in the ink layer.

<Thermal transfer image receiving material>
The thermal transfer image receiving material has, for example, a structure in which a thermal transfer image receiving material having a thermal transfer image receiving layer for receiving ink as a recording layer in the invention is provided on the support of the invention. The thermal transfer image receiving material is used, for example, in a system in which the heat-meltable ink layer of the thermal transfer material is heated by a thermal head and then the ink is melted and transferred onto the thermal transfer image receiving material.

  The above-described electrophotographic image-receiving material, silver salt photographic light-sensitive material, sublimation transfer image-receiving material, heat-sensitive recording material, and thermal transfer image-receiving material have at least a recording layer (toner image-receiving layer, silver salt photographic material) corresponding to each material. A photosensitive layer, a sublimation transfer image-receiving layer, a heat-sensitive color-developing layer, or a heat transfer image-receiving layer) is provided on the undercoat layer in the invention and is similar to the production of the ink jet recording medium described above using the support of the invention. It can be produced by a method. Examples of the electrophotographic image-receiving material, silver salt photographic light-sensitive material, sublimation transfer image-receiving material, heat-sensitive recording material, and thermal transfer image-receiving material described above are JP-A Nos. 2000-275891, 2000-292963, and 2000. Electrophotographic image receiving materials described in JP-A No. 352834 and JP-A No. 2000-13710, silver salt photographic photosensitive materials described in JP-A Nos. 60-170845 and 61-4040, and JP-A No. 3-275387. The sublimation transfer image receiving material described in JP-A-5-169802, the heat-sensitive recording material described in JP-A-5-169802, the thermal transfer image-receiving material described in JP-A-2-106392, JP-A-2-167794, etc. are preferably used. Can be used.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples. In the examples, an inkjet recording sheet is prepared as an example of the inkjet recording medium. “Part” and “%” in the examples are based on mass unless otherwise specified, and the average molecular weight and the degree of polymerization represent “weight average molecular weight” and “weight average degree of polymerization”, respectively.

[Example 1]
-Production of support A-
1) Preparation of base paper Wood pulp composed of 100 parts of LBKP was beaten to 300 ml of Canadian freeness with a double disc refiner, 0.5 parts of epoxidized behenamide, 1.0 part of anionic polyacrylamide, 0.1 part of polyamide polyamine epichlorohydrin, 0.5 parts of cationic polyacrylamide was added at an absolutely dry mass ratio to the pulp, and weighed with a long net paper machine to make a base paper of 170 g / m ² . Subsequently, in order to adjust the surface size of the base paper, the base paper is impregnated with a 4% aqueous solution of polyvinyl alcohol so as to be 0.5 g / m ^{2 in} terms of absolute dry weight, dried, and then subjected to a calender treatment. Thus, a base paper adjusted to a density of 1.05 g / cm ³ was obtained.

2) Formation of undercoat layer On the surface of the obtained base paper (on the side on which the image forming layer is provided), a pigment layer coating solution having the following composition is dried and dried using a bar coater so that the coating amount is 15.0 g / m ² It was applied and dried to form a pigment layer on the base paper. The thickness of the pigment layer was 14.2 μm.
Next, a fluorescent whitening layer coating solution having the following composition is dried on the obtained pigment layer so that the coating amount becomes 1.0 g / m ² (fluorescent whitening agent coating amount: 0.05 g / m ² ). It was applied and dried with a bar coater to form a fluorescent whitening layer on the pigment layer.
The thickness of the pigment layer after drying was 14.2 μm, and the thickness of the fluorescent whitening layer was 0.8 μm.

[Composition of coating liquid for pigment layer]
・ The following pigment dispersion 58.0g
・ Acrylic latex A 42.0g
・ Ion exchange water 21.8g

-Pigment dispersion composition-
・ Titanium dioxide 50.0g
((Product name: Taipei R-780-2, manufactured by Ishihara Sangyo Co., Ltd., average particle size 0.3 μm)
・ Na salt of special polycarboxylic acid type polymer 0.6g
(Product name: Demall EP, manufactured by Kao Corporation)
・ Ion exchange water 49.6g

-Preparation of acrylic latex A-
In a reaction vessel equipped with a stirrer, reflux condenser, dropping funnel, nitrogen inlet tube and thermometer, 583 parts of ion-exchanged water and an anionic reactive emulsifier (trade name “SE-10N”, Asahi Denka Co., Ltd.) 162 parts of a 10% aqueous solution prepared by heating) and heated to 80 ° C. Next, an aqueous catalyst solution in which 0.4 part of potassium persulfate was dissolved in 9 parts of ion-exchanged water was added, and the pre-emulsified copolymer component A (54 parts of styrene, 54 parts of methyl methacrylate, 2 parts of acrylic acid). -90 parts of ethylhexyl, 3 parts of 2-hydroxyethyl methacrylate, 2 parts of methacrylic acid, 22 parts of acrylonitrile, 150 parts of ion-exchanged water, anionic reactive emulsifier (trade name “SE-10N”, Asahi Denka Co., Ltd. Product) was added dropwise over a period of 1 hour, and then the reaction was continued for an additional hour.
Next, copolymerization component B (97 parts of styrene, 97 parts of methyl methacrylate, 10 parts of 2-ethylhexyl acrylate, 7 parts of 2-hydroxyethyl methacrylate, 10 parts of methacrylic acid, trimethoxysilylpropyl methacrylate (= γ -Methacryloxypropyltrimethoxysilane) 4 parts, an anionic reactive emulsifier (trade name "SE-10N", manufactured by Asahi Denka Co., Ltd.) 0.4 part) was added dropwise over 1 hour, The reaction was continued for another hour. During the reaction, an aqueous catalyst solution in which 1 part of potassium persulfate was dissolved in 73 parts of ion-exchanged water was added dropwise over 3 hours. After completion of the reaction, the liquid temperature was returned to room temperature, adjusted to pH 8 with a 28% aqueous ammonia solution, acrylic styrene latex (acrylic latex A), which is an acrylic water-dispersible latex (non-volatile content 34% by mass, pH 8.0, A viscosity of 400 mPa · s, an I value of 50, an O value of 135, a glass transition temperature of 44 ° C., a minimum film forming temperature of 5 ° C., and an average particle size of 60 nm were obtained.

[Composition of coating liquid for fluorescent whitening layer]
・ Water-soluble fluorescent brightener 5.0g
(Product name: Keicoal BXNL, Nippon Soda Co., Ltd., 28%)
・ Acrylic latex A 70.0g
・ Ion exchange water 10.0g

After the undercoat layer is formed, the curl adjusting layer coating solution having the following composition is further dried to a coating amount of 20.0 g / m ² on the wire surface (back surface) side where the undercoat layer of the base paper is not provided. The substrate was coated and dried with a bar coater to form a curl adjusting layer, thereby preparing a support A of the present invention.

[Composition of coating solution for curl adjustment layer]
・ The following pigment dispersion 58.0g
・ Acrylic latex A 42.0g
・ Ion exchange water 21.8g

-Pigment dispersion composition-
・ Titanium dioxide 50.0g
((Product name: Taipei R-780-2, manufactured by Ishihara Sangyo Co., Ltd., average particle size 0.3 μm)
・ Na salt of special polycarboxylic acid type polymer 0.6g
(Product name: Demall EP, manufactured by Kao Corporation)
・ Ion exchange water 49.6g

-Preparation of inkjet recording sheet-
1) Preparation of coating solution for ink receiving layer (1) Gas phase method silica fine particles, (2) ion-exchanged water, and (3) a dispersant are mixed, and a dispersing machine (trade name: KD-P, ( (7) Dissolve (4) polyvinyl alcohol, (5) boric acid, and (6) polyoxyethylene lauryl ether in ion-exchanged water after dispersion using Shinmaru Enterprises Co., Ltd. The aqueous solution was added to the above silica dispersion to prepare a coating solution for an ink receiving layer. At this time, the mass ratio between the fine particles and the water-soluble resin (PB ratio = (1) :( 4)) was 4.5: 1, and the pH of the ink receiving layer coating solution was 3.5, indicating acidity. .

<Composition of coating liquid for ink receiving layer>
(1) Gas phase method silica fine particles (fine particles) 10.0 parts (trade name: Leolosil QS-30, average primary particle diameter 7 nm, manufactured by Tokuyama Corporation)
(2) Ion-exchanged water 51.6 parts (3) Dispersant 1.0 part (trade name: Charol DC-902P, 51% aqueous solution, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
(4) Polyvinyl alcohol (water-soluble resin) 8% aqueous solution 27.8 parts (trade name: PVA-124, manufactured by Kuraray Co., Ltd., saponification degree 98.5%, polymerization degree 2400)
(5) Boric acid (crosslinking agent) 0.4 part (6) Polyoxyethylene lauryl ether (surfactant) 1.2 part (trade name: Emulgen 109P (10% aqueous solution), manufactured by Kao Corporation, HLB value 13 .6)
(7) Ion exchange water 33.0 parts

2) Preparation of inkjet recording sheet On the front surface of the support A obtained as described above, the obtained coating solution for ink-receiving layer was applied at an application amount of 200 ml / m ² using an extrusion die coater. Then, it was dried with a hot air dryer at 80 ° C. (wind speed of 3 to 8 m / sec) until the solid content concentration of the coating layer became 20%. During this period, the coating layer exhibited constant rate drying. Immediately after that, it was immersed in a basic solution having the following composition for 30 seconds to deposit 20 g / m ² on the coating layer, and further dried at 80 ° C. for 10 minutes. Thus, an ink jet recording sheet having a dry film thickness of 32 μm was produced.

<Composition of basic solution>
・ Boric acid (crosslinking agent) 0.65 part ・ Polyallylamine 12.5 parts (trade name: PAA-03, 20% aqueous solution, manufactured by Nittobo Co., Ltd .; mordant)
・ Ion-exchanged water 72.0 parts ・ Ammonium chloride (surface pH adjuster) 0.8 parts ・ Polyoxyethylene lauryl ether (surfactant) 10.0 parts (trade name: Emulgen 109P, 2% aqueous solution, HLB value 13 .6, manufactured by Kao Corporation
・ 2.0 parts of fluorosurfactant (trade name: MegaFac F1405, 10% aqueous solution, manufactured by Dainippon Ink & Chemicals, Inc.)

<Evaluation>
(Measurement of whiteness)
About the obtained support and the ink jet recording sheet, a surface provided with an undercoat layer of the support and ink jet recording using a spectrocolorimeter (trade name: X-Rite 938, manufactured by Nihon planographic base material Co., Ltd.) The whiteness of the surface provided with the ink receiving layer of the sheet for use was measured. The whiteness was measured and analyzed based on the following conditions, and the whiteness specified in JIS-L1916 (2000) was measured. The results are shown in Table 1 below.

-Condition-
・ Light source: D ⁶⁵
-Viewing angle: 2 °
Whiteness W _L : W _L = L ^* + 3a ^* -3b ^*

(Ink absorbency of support)
Using an inkjet printer (trade name: PM-980C, manufactured by Seiko Epson Corporation), Y (yellow), M (magenta), C (cyan), K (black), B (blue), A solid image of G (green) and R (red) is printed, and after about one hour, the paper is brought into contact with the image and pressed to determine the degree of transfer of the solid image (ink) to the paper according to the following criteria: evaluated.
[Standard]
AA: Almost no transfer of ink onto paper was observed, and the ink absorptivity was good.
BB: Partial transfer of ink onto paper was observed, but there was no practical problem.
CC: Many inks were transferred onto the paper, and the ink absorptivity was poor.

(Aging of the ink jet recording sheet)
Using an inkjet printer (trade name: PM-980C, manufactured by Seiko Epson Corporation), a grid-like linear pattern in which magenta and black are adjacent to each other on a sheet for inkjet recording (battle width: 0.28 mm) Was printed, and the visual density (OD ₀ ) was measured with a reflection densitometer (trade name: X Light 310TR, manufactured by X Light). Subsequently, after leaving for 3 hours after printing, it was stored in a constant temperature and humidity chamber at a temperature of 40 ° C. and a relative humidity of 90% for 1 day, and then the visual density (OD ₁ ) was measured again. The density difference before and after being left (ΔOD = OD ₀ −OD ₁ ) was calculated, and the aging blur of the inkjet recording sheet was evaluated according to the following criteria.
[Standard]
AA: ΔOD was 0.15 or less.
BB: ΔOD was more than 0.15 and less than 0.25.
CC: ΔOD was 0.25 or more.

[Example 2]
-Production of support B-
In Example 1, Support B was prepared in the same manner as in Example 1 except that the composition of the fluorescent agent white layer coating solution was changed to the following composition. Moreover, the sheet | seat for inkjet recording was produced using this and the same evaluation was performed. The results are shown in Table 1 below.

[Fluorescent whitening layer coating solution]
・ Water-soluble fluorescent brightener 5.0g
(Product name: Keicoal BXNL, Nippon Soda Co., Ltd., 28%)
・ Polyvinyl alcohol 268.0g
(Product name: PVA-105, manufactured by Kuraray Co., Ltd., degree of saponification: 98.5%, degree of polymerization: 500, solid content concentration: 9.9%)

[Example 3]
-Production of support C-
In Example 1, a support C was prepared in the same manner as in Example 1 except that the pigment layer coating solution and the fluorescent whitening layer coating solution were simultaneously applied onto the base paper by a slide curtain coater and dried. . Moreover, the sheet | seat for inkjet recording was produced using this and the same evaluation was performed. The results are shown in Table 1 below.

[Example 4]
-Production of support D-
After performing corona discharge treatment on the wire surface (back surface) side of the base paper, high-density polyethylene was coated to a thickness of 19 μm using a melt extruder to form a resin layer consisting of a mat surface (hereinafter referred to as “the mat surface”). The resin layer surface is referred to as “rear surface.”) The resin layer on the back surface side is further subjected to corona discharge treatment, and then, as an antistatic agent, aluminum oxide (trade name: Alumina Sol 100, manufactured by Nissan Chemical Industries, Ltd.) A dispersion in which silicon dioxide (trade name: Snowtex O, manufactured by Nissan Chemical Industries, Ltd.) is dispersed in water at a mass ratio of 1: 2 is applied so that the dry mass is 0.2 g / m ^2. did.
Furthermore, after the corona discharge treatment is applied to the felt surface (surface) side where the resin layer is not provided, the low density polyethylene containing 10% anatase type titanium dioxide and having an MFR (melt flow rate) of 3.8. Was extruded to a thickness of 29 μm using a melt extruder, and a thermoplastic resin layer (pigment layer) having high gloss was formed on the surface side of the base paper (hereinafter, this glossy surface is referred to as “front side”). .)
Further, the front surface resin layer was subjected to corona discharge treatment, and then the fluorescent whitening layer coating solution used in Example 1 was dried and applied in an amount of 1.0 g / m ² (fluorescent whitening agent coating amount: 0. 0). The support D was prepared by applying and drying with a bar coater so as to be 05 g / m ² ).
In addition, an ink jet recording sheet was prepared using this, and the same evaluation as in Example 1 was performed. The results are shown in Table 1 below.

[Comparative Example 1]
-Production of support E-
In Example 1, Support E was prepared in the same manner as Example 1 except that the fluorescent whitening layer was not provided. Moreover, the sheet | seat for inkjet recording was produced using this and the same evaluation was performed. The results are shown in Table 1 below.

[Comparative Example 2]
-Production of support F-
In Example 1, a support F was produced in the same manner as in Example 1 except that the pigment layer was not provided. Moreover, the sheet | seat for inkjet recording was produced using this and the same evaluation was performed. The results are shown in Table 1 below.

[Comparative Example 3]
-Production of support G-
In Example 1, a support G was produced in the same manner as in Example 1 except that the fluorescent whitening layer was not provided and the composition of the pigment layer coating solution was changed to the following composition. Moreover, the sheet | seat for inkjet recording was produced using this and the same evaluation was performed. The results are shown in Table 1 below.

[Composition of coating liquid for pigment layer]
・ The above pigment dispersion 58.0 g
・ Acrylic latex A 42.0g
・ Water-soluble fluorescent brightener 0.5g
(Product name: Keicoal BXNL, Nippon Soda Co., Ltd., 28%)
・ Ion exchange water 21.8g

[Comparative Example 4]
-Production of support H-
In Example 1, a support H was produced in the same manner as in Example 1 except that after the fluorescent whitening layer was formed on the surface of the base paper, a pigment layer was formed on the fluorescent whitening layer. Moreover, the sheet | seat for inkjet recording was produced using this and the same evaluation was performed. The results are shown in Table 1 below.

[Comparative Example 5]
In Example 4, a fluorescent brightening agent (trade name: NIKKAFLOUR KB, manufactured by Nippon Chemical Industry Co., Ltd.) is 0.01% in polyethylene in the thermoplastic resin layer (pigment layer) on the felt surface (front surface) side. %, And a support H was prepared in the same manner as in Example 4 except that the fluorescent whitening layer was not provided. Moreover, the sheet | seat for inkjet recording was produced using this and the same evaluation was performed. The results are shown in Table 1 below.

From the results in Table 1, it can be seen that the supports and the ink jet recording sheets of Examples 1 to 4 have high whiteness. On the other hand, both the support and the inkjet recording sheet of the comparative example were inferior in whiteness.
Further, the support of Examples 1 to 3 having water-dispersible latex and ink solvent absorbability and the ink jet recording sheet using the same are Example 4 and Comparative Example 5 which are ink solvent non-absorbent supports. As compared with the above, the ink absorbability of the support was excellent, and the aging of the ink jet recording sheet was suppressed.

[Example 5]
-Production of image receiving materials for digital electrophotography-
1) Preparation of coating solution for toner image receiving layer (upper layer) The following composition was mixed and stirred to prepare a coating solution for toner image receiving layer (upper layer).
[Composition of coating solution for toner image-receiving layer (upper layer)]
・ Carbana wax 15.0g
(Product name: Cellosol 524, manufactured by Chukyo Yushi Co., Ltd.)
・ Polyester resin water dispersion 100.0g
(Product name: KZA-7049, manufactured by Unitika Ltd., solid content concentration 30%, Tg: 48 ° C.)
・ Thickener 3.0g
(Product name: Alcox E30, manufactured by Meisei Chemical Co., Ltd.)
・ Anionic surfactant 0.5g
(Product name: Rapisol A-90, manufactured by NOF Corporation)
・ Ion exchange water 80.0g

1) Preparation of toner image-receiving layer (lower layer) coating solution The following compositions were mixed and stirred to prepare a toner image-receiving layer (lower layer) coating solution.
[Composition of coating solution for toner image-receiving layer (lower layer)]
・ Styrene acrylic varnish 100.0g
(Brand name: BH-997L, manufactured by Seiko Chemical Co., Ltd., solid concentration 26.8%, Tg: 62 ° C.)
・ Anionic surfactant 1.5g
(Product name: Rapisol A-90, manufactured by NOF Corporation)
・ Ion exchange water 20.0g

3) Formation of toner image-receiving layer A toner image-receiving layer (lower layer) coating solution and a toner image-receiving layer (upper layer) coating solution are sequentially applied to the surface of the fluorescent whitening layer of the support A and dried using a bar coater. Thus, an image receiving layer was formed to obtain an image receiving material for digital electrophotography. The coating amount of the image receiving layer (lower layer) was 5.0 g in dry mass, and the image receiving layer (upper layer) was 10.0 g in dry mass.
After coating, the image receiving layer was dried online with hot air. In the drying, the drying air volume and temperature were adjusted so as to dry within 2 minutes after coating. The drying point was the point at which the coating surface temperature was the same as the wet bulb temperature of the drying air.

  When the whiteness defined by JIS-L1916 (2000) on the surface of the toner image-receiving layer of the obtained digital electrophotographic image-receiving material was measured by the above-mentioned method, it showed a good value of 151.6.

Claims (11)

  A support for an image recording material, comprising a pigment layer containing a white pigment and a fluorescent whitening layer containing a fluorescent whitening agent in this order on a substrate.   The support for an image recording material according to claim 1, wherein the white pigment is titanium dioxide.   The support for an image recording material according to claim 1, wherein the fluorescent whitening agent is a water-soluble fluorescent whitening agent.   The support for an image recording material according to claim 3, wherein the water-soluble fluorescent brightening agent is a stilbene compound.   The support for an image recording material according to any one of claims 1 to 4, wherein the pigment layer contains a thermoplastic resin.   6. The support for an image recording material according to claim 5, wherein the thermoplastic resin is a water-dispersible latex.   The said fluorescent whitening layer contains a thermoplastic resin, The support body for image recording materials of any one of Claims 1-6 characterized by the above-mentioned.   The support for an image recording material according to claim 7, wherein the thermoplastic resin is a water-dispersible latex.   The support for an image recording material according to any one of claims 1 to 8, wherein the pigment layer and the fluorescent whitening layer are formed on the substrate by a simultaneous multilayer coating method.   An image recording comprising the support for an image recording material according to any one of claims 1 to 9, and a recording layer provided on the fluorescent whitening layer of the support for the image recording material. material.   11. The image according to claim 10, wherein the recording layer is any one of an ink receiving layer, a toner image receiving layer, a silver salt photographic photosensitive layer, a sublimation transfer image receiving layer, a heat sensitive color developing layer, and a heat transfer image receiving layer. Recording material.