JP2011073332A - Coating liquid for forming ink receiving layer, and recording sheet with ink receiving layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating liquid which can form an ink receiving layer excellent in ink absorbency and color development without causing the lowering of transparency, haze, adhesion with a medium to be recorded, scratch resistance or the like. <P>SOLUTION: The coating liquid for forming an ink receiving layer comprises: a phosphate modification hydrated alumina particle; a matrix forming component; and a dispersion medium where a phosphorus content in the phosphate modification hydrated alumina particle is in a range of 1-35 wt.% in terms of P<SB>2</SB>O<SB>5</SB>. The hydrated alumina particle is fiber-like pseudoboehmite alumina. The crystallite diameter of the phosphorus modification hydrated alumina particle is in a range of 30-150 angstrom, the pore volume measured by a nitrogen adsorption process is 0.8-2.5 ml/g, and the average pore diameter is in a range of 5-30 nm. The phosphorus modification hydrated alumina particle is obtained by spraying and drying the mixed dispersion of a hydrated alumina particle and a phosphorus compound. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention has an ink-receiving layer-forming coating solution containing phosphorus-modified alumina hydrate particles and a matrix-forming component, and an ink-receiving layer formed on a base sheet using the ink-receiving layer-forming coating solution It relates to a recording sheet.

  The ink jet recording method employs a method of recording images, characters, etc. by spraying fine droplets of pigment or dye ink onto a recording medium such as paper or PET film. Is popular. Furthermore, images recorded by the multi-color inkjet method can obtain a recording that is comparable to multi-color printing by the plate-making method and printing by the color photographic method. Since it is cheaper than multi-color printing or printing, it has been widely applied for full-color image recording. Therefore, in order to cope with improvement in recording characteristics such as high-speed recording, high definition, full color, etc., a receiving layer excellent in ink high absorbability, color reproducibility and the like has been developed.

In order to solve this problem, many recording media having a coating layer using alumina hydrate and alumina hydrate having a boehmite structure have been proposed.
For example, a recording medium is disclosed in which the average pore size of the coating layer is 10 to 30 angstroms and has a narrow pore size distribution. If the average pore size is small, the adsorptivity of the ink is good but the ink absorptivity. However, there is a known defect that bleeding occurs due to insufficient.

  In addition, as an ink receiving layer, Japanese Patent Application Laid-Open No. 7-232475 (Patent Document 1) uses alumina hydrate, the average pore radius is 20 to 200 angstroms, and the half width of the pore diameter distribution is 20 to 150 angstroms. An ink-receiving layer is disclosed.

  Japanese Patent Application Laid-Open No. 8-310115 (Patent Document 2) discloses a recording medium having an ink receiving layer containing alumina hydrate and a water-soluble polymer, wherein the primary particles of alumina hydrate are aggregated by anions. An ink-receiving layer comprising an aggregate structure and a water-soluble polymer is disclosed.

  In JP-A-6-199034 (Patent Document 3), an alumina hydrate having an average pore radius of 30 to 80 Å formed from boehmite sol having a secondary aggregated particle diameter of 100 to 160 nm on a substrate is disclosed. An alumina hydrate porous layer having a thickness of 5 to 40 μm and an upper layer formed from boehmite sol having a secondary aggregated particle diameter of 300 to 500 nm and having an average pore radius of 50 to 100 Å A recording sheet having a thickness of 1 to 20 μm is disclosed.

  Generally, reducing the particle size of the metal oxide introduced into the ink receiving layer may improve the transparency and smoothness of the ink receiving layer. However, if the particles are packed closely, large pores are formed. However, there was a drawback that although ink resistance was poor, the scratch resistance was high.

  Japanese Patent Application Laid-Open No. 5-32413 (Patent Document 4) discloses a recording medium using secondary particles in which small primary particles are aggregated. Since the agglomeration occurs rapidly, that is, the stability of the coating liquid for forming the ink receiving layer is low, the scratch resistance is lowered, and it is difficult to satisfy both the scratch resistance and the ink absorbency at the same time. In addition, when a metal oxide having a large particle size is used, the pore size is increased and the ink absorbency is increased, but the transparency, haze, smoothness of the ink receiving layer, the adhesion between the recording medium and the ink receiving layer, the ink There was a tendency for the strength and scratch resistance of the demand layer to deteriorate.

JP-A-7-232475 JP-A-8-310115 Japanese Patent Laid-Open No. 6-199034 JP-A-5-32413

  In recent years, in order to increase ink absorption speed and prevent ink bleeding, it has been required to further reduce the thickness of the ink receiving layer to suppress curling, and to improve adhesion, scratch resistance, transparency, and the like. . For this purpose, it was considered to use inorganic fine particles having a large average particle diameter for the ink receiving layer or secondary particles obtained by agglomerating the fine particles even if the average particle diameter is small. There are problems such as insufficient, glossiness, haze increase, and transparency.

  As a result of intensive investigations to solve such problems, the present inventors have found that the ink receiving layer using the phosphorus-modified alumina hydrate particles obtained by spray drying has a large pore volume, especially the pore diameter. In the present invention, the pore volume of 5 to 30 nm is increased, and the ink absorbency and color developability are improved without decreasing transparency, haze, adhesion to a recording medium, scratch resistance, and the like. It came to complete.

The invention according to the present invention is configured as follows.
[1] comprising phosphate-modified alumina hydrate particles, a matrix-forming component, and a dispersion medium,
A coating liquid for forming an ink-receiving layer, wherein the phosphoric acid-modified alumina hydrate particles have a phosphorus content in the range of 1 to 35% by weight as P ₂ O ₅ .
[2] The coating solution for forming an ink receiving layer according to [1], wherein the alumina hydrate particles are fibrous pseudoboehmite alumina.
[3] The crystallite diameter of the phosphorus-modified alumina hydrate particles is in the range of 30 to 150 Å, the pore volume measured by the nitrogen adsorption method is 0.8 to 2.5 ml / g, and the average pore diameter is 5 The coating solution for forming an ink receiving layer according to [1] or [2], which is in the range of ˜30 nm.
[4] The ink-receiving layer-forming coating according to [1] to [3], wherein the phosphorus-modified alumina hydrate particles are obtained by spray-drying a mixed dispersion of alumina hydrate particles and a phosphorus compound. liquid.
[5] The matrix-forming component is one or more resins selected from polyacrylic resins, polyvinyl alcohol resins, polyvinylpyrrolidone resins, urethane resins, and swellable resin particles having a core-shell structure [1] to [ 4] A coating solution for forming an ink receiving layer.
[6] A substrate sheet and an ink receiving layer formed on the substrate sheet, and the ink receiving layer is formed using the ink receiving layer forming coating liquid of [1] to [5]. A recording sheet with an ink-receiving layer.
[7] The recording sheet with an ink receiving layer according to [6], wherein the content of phosphorus-modified alumina hydrate particles in the ink receiving layer is in the range of 5 to 95% by weight as a solid content.
[8] The pore volume of the ink receiving layer measured by mercury porosimetry is in the range of 0.2 to 1.5 ml / g, and the average pore diameter is in the range of 10 to 60 nm [6] or [7] Recording sheet with ink receiving layer.

  According to the present invention, since it contains phosphorus-modified alumina hydrate particles, it has a pore diameter in a specific range and a large pore diameter. Therefore, the ink absorbability is excellent and there is no bleeding, transparency, haze, To provide an ink-receiving layer-forming coating liquid and an ink-receiving layer-attached recording sheet that can be suitably used for forming an ink-receiving layer having excellent adhesion to a recording medium, scratch resistance, color development and the like. it can.

Hereinafter, the present invention will be specifically described.
[Ink-receiving layer forming coating solution]
First, the ink receiving layer forming coating solution according to the present invention will be described.
The coating liquid for forming an ink receiving layer according to the present invention comprises phosphoric acid modified alumina hydrate particles, a matrix forming component, and a dispersion medium, and the phosphorous content in the phosphoric acid modified alumina hydrate particles is P. ₂ O ₅ is in the range of 1 to 35% by weight.

Phosphorus-modified alumina hydrate particles The phosphor-modified alumina hydrate particles used in the present invention have phosphoric acid supported on the surface of the alumina hydrate particles.

Examples of the alumina hydrate particles include aluminum hydroxide, crystal water, aluminum oxide containing hydrated water, and the like. Particularly, fibrous pseudoboehmite alumina (Al ₂ O ₃ .nH ₂ O, n: 0.5 to 2). .5) is preferred.

Fibrous pseudo boehmite alumina is a fibrous secondary particle in which primary particles are bundled.
The primary particle size of the fibrous pseudoboehmite alumina is such that the average length (L ₁ ) is approximately ₁ to 40 nm, preferably 2 to 30 nm, and the average width (W ₁ ) is approximately 0.5 to 5 nm. Preferably it exists in the range of 1-4 nm.

The aspect ratio is in the range of 2-40, preferably 4-20.
If the primary particles are short, they become amorphous, and the pore size distribution becomes wide when the ink receiving layer is formed. Particularly, the pore volume with an average pore size of 5 to 30 nm becomes small, and the ink absorbability is insufficient. There is a case.

Even if the primary particles are too long, when the ink receiving layer is formed, the average pore diameter and the average pore volume become too large, and ink bleeding may occur or the color developability of the ink may be reduced.
In addition, it is difficult to obtain a primary particle having a narrow average width (W ₁ ), and even if it is obtained, it becomes amorphous and ink absorbability may be insufficient. Even if the average width (W ₁ ) of the primary particles is too large, the particle size of the secondary particles may be too large, and transparency may be reduced or haze may be increased when the ink receiving layer is formed. .

The average length (L ₂ ) of the secondary particles of fibrous pseudoboehmite alumina is approximately 50 to 400 nm, preferably 60 to 300 nm, and the average width (W ₂ ) is approximately 1 to 10 nm, preferably 2 to 8 nm. It is in the range.

  Even if the secondary particles of fibrous pseudoboehmite alumina are too long, the pore volume when the ink receiving layer is formed is small, and the ink absorbability may be insufficient. Even if the fibrous pseudoboehmite alumina is too short, when it is used as an ink receiving layer, the pore volume becomes too large, and ink bleeding may occur or transparency may be lowered.

  The measurement method of the average length and average width of the primary particles and secondary particles described above is obtained by taking a transmission electron micrograph (TEM), measuring each value of 50 secondary particles, and obtaining the average value. .

  The crystallite diameter of fibrous boehmite alumina is preferably in the range of 30 to 150 angstroms, more preferably 40 to 130 angstroms. The crystallite diameter is the minimum unit of a uniform crystal phase, and a normal crystal is an aggregate of these.

  When the crystalline boehmite alumina has a crystallite diameter of less than 30 angstroms, the pore diameter distribution becomes wider when the ink receiving layer is formed (the pore volume with an average pore diameter of 5 to 30 nm becomes smaller), and the ink absorbency. May be insufficient.

When the fiber boehmite alumina has a small crystallite diameter, when it is used as an ink receiving layer, ink bleeding may occur or transparency may be lowered.
Such a crystallite diameter measurement method was obtained by measuring the half width of a peak near 2θ = 14.4 degrees with an X-ray diffractometer and calculating it according to Scherrer's equation.
D = Kλ / βcosθ
D: crystallite diameter (angstrom), K: Scherrer constant, λ: X-ray wavelength (1.7889 angstrom Cu lamp), β: half width (rad), θ: reflection angle.

The phosphorus content in the phosphorus-modified alumina hydrate particles used in the present invention is preferably 1 to 35% by weight, more preferably 5 to 30% by weight, as P ₂ O ₅ .
If the phosphorus content is less than 1% by weight, the desired secondary particle size may not be achieved, and ink absorption may be insufficient when the ink receiving layer is formed.

  When the phosphorus content exceeds 35% by weight, the secondary particle size increases and the pore volume becomes too large, resulting in a decrease in transparency, an increase in haze, and ink bleeding when the ink receiving layer is formed. There is.

Moreover, it is preferable that the pore volume measured by the nitrogen adsorption method of phosphorus-modified alumina hydrate particles is in the range of 0.8 to 2.5 ml / g, more preferably 1.0 to 2.3 ml / g.
If the pore volume of the phosphorus-modified alumina hydrate particles is small, the ink absorbability may be lowered when the ink receiving layer is formed.

Even if the pore volume of the phosphorus-modified alumina hydrate particles is too large, when the ink receiving layer is formed, transparency may be lowered, haze may be increased, and ink bleeding may occur.
The average pore diameter of the phosphorus-modified alumina hydrate particles is preferably in the range of 5 to 30 nm, more preferably 10 to 25 nm.

  When the average pore diameter of the phosphorus-modified alumina hydrate particles is small, the pore diameter is too small when the ink receiving layer is formed, and the ink absorbability may be insufficient. Even if the average pore diameter is too large, ink bleeding may occur when the ink receiving layer is formed, or transparency may be lowered.

  The phosphorus-modified alumina hydrate particles according to the present invention can be obtained by mixing the alumina hydrate particle dispersion and a phosphorus compound or a phosphorus compound aqueous solution, and spray-drying the mixed dispersion. The pore volume and pore diameter of the particles can be determined by a nitrogen adsorption pore distribution measuring device.

  By selecting the pore volume of the phosphate-modified alumina hydrate within the above range, the pore volume of the ink receiving layer can be adjusted, and thereby the ink absorbability can be adjusted.

As the phosphorus compounds, phosphoric acid, tripolyphosphate, alkali phosphates, phosphoric acid alkaline earth salts, and the like. In particular, phosphoric acid can be suitably used because it is easy to obtain phosphorus-modified alumina hydrate particles having the desired average pore size and pore volume.

As described above, the mixing ratio of the alumina hydrate particles and the phosphorus compound at this time is such that the phosphorus content in the obtained phosphorus-modified alumina hydrate particles is 1 to 35% by weight as P ₂ O ₅ , It is preferable to mix so that it may become the range of 5-30 weight%.

The concentration of the mixed dispersion is preferably 3 to 30% by weight, more preferably 5 to 25% by weight, expressed as (P ₂ O ₅ + Al ₂ O ₃ ).
When the concentration of the mixed dispersion liquid is low, the particle diameter of the obtained phosphorus-modified alumina hydrate particles becomes small, and the economic efficiency decreases due to a decrease in the recovery rate of the phosphorus-modified alumina hydrate particles.

If the concentration of the mixed dispersion exceeds 30% by weight expressed as (P ₂ O ₅ + Al ₂ O ₃ ), the viscosity of the mixed dispersion becomes 10,000 mPa · sec or more, which makes handling difficult and spray drying difficult. There is a case.

As a method of spray drying, a conventionally known method can be adopted, but the mixed dispersion is sprayed into hot air at 100 to 500 ° C. by a nozzle method or a disk method.
If the temperature of the hot air is low, the powder cannot be recovered because it cannot be sufficiently dried. Even when the temperature of the hot air is too high, the dispersibility of the phosphorus-modified alumina hydrate particles decreases when preparing a coating liquid for forming an ink receiving layer, and an ink receiving layer having a desired pore diameter and pore volume is obtained. It may not be possible.

  The phosphorus-modified alumina hydrate particles thus obtained are spherical particles having an average particle diameter of approximately 40 to 100 μm, and have less particle fusion than those dried with a dryer or the like, and become agglomerated. In addition, when preparing the ink receiving layer forming coating liquid of the present invention described later, it is easily dispersed in the secondary particles when dispersed in a dispersion medium, and has a desired pore diameter and pore volume. It is possible to form an ink receiving layer that is excellent in absorbency and transparency, has low haze, has no ink bleeding, and has excellent absorbency.

Matrix-forming component As the matrix-forming component, an organic resin-based matrix-forming component is preferably used.

  As the organic resin matrix component, any of conventionally known thermosetting resins and thermoplastic resins can be employed. For example, conventionally used polyester resins, polycarbonate resins, polyamide resins, polyphenylene oxide resins, thermoplastic acrylic resins, vinyl chloride resins, fluororesins, vinyl acetate resins, silicone rubber and other thermoplastic resins, urethane resins, melamine resins And thermosetting resins such as silicon resin, butyral resin, reactive silicone resin, phenol resin, epoxy resin, unsaturated polyester resin, and thermosetting acrylic resin. Further, it may be a copolymer or modified body of two or more of these resins. In the case of a curable resin, the matrix-forming component is a monomer or oligomer before the reaction.

  These resins may be emulsion resins, water-soluble resins, and hydrophilic resins. Further alternatively, an ultraviolet curable resin or an electron beam curable resin may be used. In the case of a thermosetting resin, a curing catalyst may be included.

Specifically, a polyfunctional (meth) acrylic acid ester resin having a functional group such as a silyl group, a hydroxyl group, an amino group, a carboxyl group, or a sulfo group can be used as the organic resin matrix forming component. Specifically, polyacryl such as hexaerythritol tripentaacrylate, pentaerythritol triacrylate, diethylaminomethyl methacrylate, dimethylaminomethyl methacrylate, 2-hydroxy-3-acryloyloxypropyl acrylate, methoxytriethylene glycol dimethacrylate, butoxydiethylene glycol methacrylate, etc. Resin, polyvinyl alcohol or modified product thereof (cation modification, anion modification, silanol modification), starch or modification product (oxidation, etherification), gelatin or modification product thereof, casein or modification product thereof, carboxymethyl cellulose, gum arabic, hydroxyethyl cellulose , Cellulose derivatives such as hydroxypropylmethylcellulose, SBR latex, NB Latex, conjugated diene copolymer latex such as methyl methacrylate-butadiene copolymer, functional group modified polymer latex, vinyl copolymer latex such as ethylene vinyl acetate copolymer, polyvinyl pyrrolidone, maleic anhydride or copolymer thereof It may be a polymer, an acrylate copolymer, a mixture thereof, or two or more copolymers or modified products of these resins. In addition, polyfunctional (meth) acrylic acid ester resins having a functional group such as a vinyl group, a urethane group, an epoxy group, a (meth) acryloyl group, or a CF ₂ group, and emulsion-based fine particles can be suitably employed.

  Specifically, pentaerythritol tetraacrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol hexaacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, n-lauryl acrylate, n-stearyl acrylate, 1,6-hexanediol dimethacrylate, perfluorooctylethyl methacrylate, trifluoroethyl methacrylate, urethane acrylate, acrylic Cross-linked copolymer fine particles, urethane-based cross-linked copolymer fine particles, acrylic-urethane-based cross-linked copolymer Particles and the like and mixtures thereof.

  In this invention, it is preferable that it is 1 or more types of resin chosen from polyacrylic acid-type resin, polyvinyl alcohol-type resin, and polyvinylpyrrolidone-type resin. When these resins are used, it is possible to obtain an ink receiving layer having a strong affinity with phosphorus-modified alumina hydrate particles, excellent transparency, haze, dye fixing property, and the like, and excellent scratch resistance.

Furthermore, in the present invention, swellable resin particles having a core-shell structure can also be suitably used as a matrix-forming component.
The swellable resin particles having a core-shell structure are composed of a resin core portion and a shell portion on the surface of the core portion, and the shell portion is composed of an organic chain having a functional group. Such shell portions and shell portions and phosphorus-modified alumina hydrate particles are combined to form a matrix.

  As the resin core part, conventionally known resin fine particles can be used. For example, polyester resin, polyamide resin, polyphenylene oxide resin, acrylic resin, vinyl chloride resin, fluorine resin, vinyl acetate resin, silicone rubber and other thermoplastic resins, urethane resin, melamine resin, silicon resin, butyral resin, reactive silicone resin , Fine particles such as phenol resin, epoxy resin and unsaturated polyester resin.

  In the present invention, acrylic resin fine particles, urethane resin fine particles, and vinyl resin fine particles are suitably used as the resin core portion. These resin fine particles are easy to prepare desired swellable resin particles having a core-shell structure, and have a refractive index close to those of alumina fine particles, silica fine particles and the like commonly used as inorganic fine particles described later, For this reason, light scattering is suppressed, and an ink receiving layer excellent in transparency, haze, and the like can be obtained.

  The average particle size of the core resin fine particles is preferably in the range of 10 to 150 nm, more preferably 15 to 100 nm. If the core resin fine particles are small, a sufficient swelling effect cannot be obtained, so that there is no sufficient volume of pores to absorb the ink, and since the pore diameter is small, dye absorption and fixing are not possible. May be sufficient. If the core resin fine particles are too large, cracks may occur in the receiving layer when ink is absorbed.

The shell portion is composed of an organic chain having a functional group.
The organic chain is not particularly limited as long as it can bind to the resin core, but is selected from methacrylic acid (MMA), 2-hydroxyethyl acrylate, n-butyl acrylate, and methyl methacrylate 1 It is preferably a chain polymer composed of a resin of more than one kind.

  These polymers preferably have one or more functional groups selected from carbonyl group, hydroxyl group, phenyl group, cyano group, ether group, carboxyl group, thiol group, methoxy group, and ethylene group.

  The swellable resin particles having a core-shell structure in the ink receiving layer are formed in a coating liquid, which will be described later. Swells and shrinks.

  The average particle diameter of the swellable resin particles having a core-shell structure in the ink receiving layer cannot be measured or observed, but is estimated to be approximately 12 to 300 nm, preferably 15 to 250 nm, estimated from the particles in the coating solution. It is done.

The thickness of the shell layer is estimated to be in the range of 2 to 100 nm, and further 5 to 80 nm.
The content of the swellable resin particles having a core-shell structure in the ink receiving layer is preferably in the range of 10 to 80% by weight, more preferably 20 to 60% by weight as the solid content.

  If there are few swellable resin particles in the ink receiving layer, pores with a volume sufficient to absorb ink cannot be formed, causing bleeding, or swelling after absorbing ink and shrinking due to drying. Insufficient gas barrier properties may result in insufficient gas barrier properties. Even if there are too many swellable resin particles having a core-shell structure, the entire ink receiving layer swells, the cross-linking between the components is cut, and cracks may occur when dried.

  In the ink receiving layer forming coating solution, the dispersion medium and solvent are occluded between the chain polymers constituting the shell layer, and the swellable resin particles are swollen, but in the ink receiving layer, the solvent is dried and dried. As it disappears, it shrinks. In such an ink receiving layer, when the ink is applied, the receiving layer swells so that the dye can penetrate and be fixed inside the ink receiving layer, and the pigment can be fixed on the surface of the ink receiving layer. The swelling state disappears and shrinks with transpiration.

The method for producing the swellable resin particles having such a core-shell structure can be produced according to the method described in TECHNO-COSMOS 2005 Mar. VoL.18.
For example,
(1) Polymer emulsifier method: A water-soluble polymer resin (emulsifier) is used to prepare a pre-emulsion solution of an acrylic monomer, which is dropped into an aqueous medium together with a polymerization initiator, and polymerized to swell the resin. Particles (emulsion resin) are obtained. At this time, a water-soluble polymer resin used as an emulsifier is present in the particle surface layer (shell portion).
(2) Two-stage emulsion polymerization method: First, a water-soluble carboxylic acid-supporting hydrophilic emulsion resin that becomes a shell portion is synthesized. A carboxylic acid-carrying hydrophilic emulsion resin is obtained by dropping a pre-emulsion solution of an acrylic monomer prepared using an anionic reactive emulsifier together with a polymerization initiator into a water medium to cause a polymerization reaction. (The number average molecular weight of the emulsion resin at this time is approximately 5000 to 20000.

Next, using the obtained carboxylic acid-carrying hydrophilic emulsion resin particles as a polymerization field, the acrylic monomer mixture is dropped as monomer oil droplets without using an emulsifier to obtain a core-shell emulsion resin in which the hydrophobic core portion is polymerized.
The obtained core-shell emulsion resin is neutralized with an amine and the shell portion is water-solubilized to obtain swellable resin particles in which the water-soluble resin (shell portion) encapsulates the hydrophobic core portion.

Dispersion medium The dispersion medium used in the coating liquid for forming an ink receiving layer of the present invention can dissolve or disperse the matrix-forming component and, if necessary, the polymerization initiator, and uniformly disperse the phosphoric acid-modified alumina hydrate particles. If it can disperse | distribute, there will be no restriction | limiting in particular, A conventionally well-known dispersion medium can be used.

Specifically, alcohols such as water, methanol, ethanol, propanol, 2-propanol (IPA), butanol, diacetone alcohol, furfuryl alcohol, tetrahydrofurfuryl alcohol, ethylene glycol, hexylene glycol, isopropyl glycol; acetic acid Esters such as methyl ester, ethyl acetate, butyl acetate; ethers such as diethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether Acetone, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, acetone Ketones such as acetate, methyl cellosolve, ethyl cellosolve, butyl cellosolve, toluene, cyclohexanone, isophorone and the like.
These may be used alone or in combination of two or more. Moreover, you may add an antifoamer and a leveling agent as needed.

Polymerization initiator (crosslinking agent, curing agent)
In the present invention, a polymerization initiator (crosslinking agent, curing agent) can be used as necessary.
The polymerization initiator may be a general metal salt, preferably an aluminum salt. Specifically, aluminum chloride, aluminum nitrate, aluminum hydrochloride, aluminum acetate, and the like. Moreover, when using polyvinyl alcohol etc. as a matrix component, boric acid can also be used suitably.

  The crosslinking agent (curing agent) is not particularly limited as long as it can form a network structure by crosslinking the swellable resin particles, resin monomer, resin polymer, and inorganic fine particles, and a conventionally known crosslinking agent can be used.

As a crosslinking agent used in the present invention, a carbodiimide compound (compound having a carbodiimide group), a polycarbodiimide compound: several thousand molecular weight, a cyanide compound, a melamine compound, an oxazoline compound (compound having an oxazoline group), an isocyanate compound (-N = It is preferable that it is 1 or more types chosen from the compound which has C = O as a partial structure.
Examples of the carbodiimide compound include carbodilite V-01 and V-02 (manufactured by Nisshinbo Co., Ltd.), and examples of the oxazoline compound include Epocross (manufactured by Nippon Shokubai Co., Ltd.).

Coating Solution Composition The total solid content of the coating solution for forming an ink receiving layer is preferably in the range of 1 to 60% by weight, more preferably 2 to 50% by weight.
When the total solid concentration of the coating liquid for forming the ink receiving layer is less than 1% by weight, a predetermined film thickness may not be obtained by a single application. For this reason, it is necessary to repeat application and drying. May be disadvantageous in gender. If the total solid concentration is too high, the thickness of the resulting receiving layer tends to be non-uniform.

  The concentration of the phosphate-modified alumina hydrate particles in the coating solution for forming the ink receiving layer is a concentration in the range of 0.05 to 57% by weight, further 0.1 to 47.5% by weight as the solid content. It is preferable.

  If the content of phosphoric acid-modified alumina hydrate particles is too low, the amount of phosphoric acid-modified alumina hydrate particles is small and the matrix-forming component is increased, so that a sufficient pore volume cannot be obtained. Absorption and dye fixability may be insufficient. Even if the content of phosphoric acid-modified alumina hydrate particles is too large, adhesion to the substrate, strength, transparency, haze, scratch resistance, etc. may be insufficient.

  The concentration of the matrix forming component in the ink receiving layer forming coating solution is preferably 0.05 to 57% by weight, more preferably 0.1 to 47.5% by weight as the solid content.

  When the content of the matrix component is small as a solid content, the ratio of the phosphoric acid-modified alumina hydrate particles increases, and the adhesion to the substrate may be lowered or the strength may be insufficient. Even if the content of the matrix component is too large, the thickness of the ink receiving layer tends to be non-uniform.

When the weight ratio of the phosphate-modified alumina hydrate particles to the matrix-forming component is 5:95 to 95: 5, preferably 10:90 to 90:10, the effects of the present invention can be sufficiently exerted. .
The method for preparing the coating solution is not particularly limited as long as each component can be mixed at the above ratio, and a known mixing method is employed.

The above-mentioned coating solution for forming the ink receiving layer is formed by a bar coating method, a blade coating method, an air knife method, a roll coating method, a brush coating method, a gravure coating method, a kiss coating method, an extrusion method, a slide hopper (slide bead) method, or a curtain. The ink receiving layer can be formed by applying to a substrate by a known method such as a coating method or a spray method, drying, and curing by a conventional method such as ultraviolet irradiation or heat treatment.
Next, the recording sheet with an ink receiving layer according to the present invention will be described.

[Recording sheet with ink receiving layer]
The recording sheet with an ink receiving layer according to the present invention comprises a base sheet and an ink receiving layer formed on the base sheet, and the ink receiving layer uses the coating liquid for forming the ink receiving layer. It is characterized by being formed.

Substrate sheet As the substrate sheet used in the present invention, a conventionally known sheet can be used without any particular limitation. Paper having an appropriate size, non-size paper, resin-coated paper, glass, polycarbonate, acrylic And plastic panels such as plastic resins, polyethylene terephthalate (PET), triacetyl cellulose (TAC), cyclopolyolefin, norbornene, and plastic panels. Among these, paper and resin base materials can be preferably used. Moreover, the base material with a film in which another film was formed on such a base material can also be used. Examples of other coatings include conventionally known primer films, hard coat films, and mat layer films.

Phosphorus-modified alumina hydrate particles The same phosphorous-modified alumina hydrate particles as described above are used.
The content of the phosphorus-modified alumina hydrate particles in the ink receiving layer is preferably in the range of 5 to 95% by weight, more preferably 10 to 90% by weight as the solid content. If the content of phosphorus-modified alumina hydrate particles is low, the ink absorbency may be insufficient due to the small amount of particles, and if it is too high, the matrix component is low, adhesion to the substrate, and transparency. , Haze, scratch resistance, etc. may be insufficient.

As the matrix component , the organic resin matrix component derived from the organic resin matrix forming component described above is used. The thermosetting resin matrix component is a reaction product such as a cured product, a polymer, a hydrolysis / polycondensation product. In addition, a matrix-forming component is a matrix component of a thermoplastic resin matrix that does not react or change.

The amount of the matrix component in the ink receiving layer is preferably 5 to 95% by weight, more preferably 10 to 90% by weight as the solid content.
If the content of the matrix component is small, adhesion to the substrate, transparency, haze, scratch resistance, etc. may be insufficient. If the content of the matrix component is too large, the ink absorbency may be insufficient due to the small amount of particles.

The pore volume measured by the mercury intrusion method of the ink receiving layer is preferably in the range of 0.2 to 1.5 ml / g, more preferably 0.4 to 1.2 ml / g.
When the pore volume of the ink receiving layer is less than 0.2 ml / g, a sufficient ink absorption rate cannot be obtained, and ink bleeding or repellency may occur.

If the pore volume of the ink receiving layer exceeds 1.5 ml / g, the pore volume may be too large and ink bleeding may occur, the strength of the ink receiving layer may decrease, or cracks may occur.
At this time, the average pore diameter of the ink receiving layer is preferably in the range of 10 to 60 nm, more preferably 12 to 40 nm.

When the average pore diameter of the ink receiving layer is less than 10 nm, as in the case where the pore volume is small, a sufficient ink absorption rate cannot be obtained, so that ink bleeding and repelling may occur.
Even if the average pore diameter of the ink receiving layer exceeds 60 nm, ink bleeding may occur, the dye fixing property may be insufficient, the strength of the ink receiving layer may be reduced, and cracks may occur.

  The pore diameter and pore volume of the ink receiving layer can be adjusted by the particle diameter and content of the phosphorus-modified alumina hydrate particles used. In order to increase the pore diameter and the pore volume, phosphoric acid-modified alumina hydrate particles having a large particle diameter may be used and the content of the matrix component may be reduced. In addition, since the pore volume of the phosphate-modified alumina hydrate particles also contributes, the use of phosphorus-modified alumina hydrate particles having a large pore volume reduces the pore volume of the ink receiving layer. Can be bigger.

The thickness of the ink receiving layer according to the present invention is preferably 5 μm to 100 μm, more preferably 10 μm to 50 μm.
If the thickness of the ink receiving layer is thin, ink absorbability may be insufficient. In addition, when the thickness of the ink receiving layer exceeds 100 μm, it is difficult to obtain by one coating, and it is problematic in terms of economy to perform multiple coatings, and the ink receiving layer is cracked. Or curling (curving or warping).

  The recording sheet with an ink-receiving layer according to the present invention can be produced by applying the above-described coating liquid for forming an ink-receiving layer onto a base sheet, drying and curing. Specifically, the ink receiving layer forming paint is a bar coating method, blade coating method, air knife method, roll coating method, brush coating method, gravure coating method, kiss coating method, extrusion method, slide hopper (slide bead) method. The receptor layer can be formed by coating on a substrate sheet by a known method such as curtain coating or spraying, drying, and curing by a conventional method such as ultraviolet irradiation or heat treatment.

As a method for performing recording by applying ink to the recording sheet with the ink receiving layer, an ink jet recording method is preferable. In this recording method, the ink is effectively separated from the nozzle to apply the ink to the recording medium. Any method can be used as long as the method is obtained.
In the recording sheet with an ink receiving layer of the present invention, a glossy film may be further formed on the ink receiving layer.

[Example]
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

[Example 1]
Preparation of Phosphorus-Modified Alumina Hydrate Particles (1) As an alumina, an aqueous solution of sodium hydroxide having a concentration of 5% by weight was added dropwise to 10,000 g of an aqueous solution of aluminum chloride having a concentration of 3% by weight to adjust pH to 7. Then, it stirred at 25 degreeC for 1 hour, and obtained the alumina hydrate gel. This was washed with pure water with an ultra-thin film until the conductivity reached 200 μS / cm at a solid concentration of 5% by weight.

  100 g of phosphoric acid having a concentration of 50% by weight was added to 5,000 g of the washed alumina hydrate gel (concentration 5% by weight), followed by aging at 90 ° C. for 1 hour. Then, using a spray equipped with a 1.5 mmφ nozzle, the solution was spray-dried under the conditions of a liquid supply speed of 0.5 L / min, a spray inlet temperature of 400 ° C., and an outlet temperature of 150 ° C. to obtain phosphorus-modified alumina hydrate particles (1 ) Was prepared.

  Composition analysis of the obtained phosphorus-modified alumina hydrate particles (1) was performed by ICP analysis and ion chromatography analysis, crystal structure by X-ray diffraction and average primary particle diameter, average secondary particle diameter, average measured by the following conditions The pore diameter and pore volume are shown in Table 1.

A dispersion liquid having an average primary particle diameter of phosphorus-modified alumina hydrate particles (1) having a solid content concentration of 0.001% by weight was dropped on a grid of a transmission electron microscope and dried at room temperature. (TEM) Photographs were taken, the particle size of 50 particles was randomly measured, and this average value was taken as the primary particle size. For the fibrous particles, the short diameter and long diameter were measured.

Measurement of average pore diameter and pore volume by nitrogen adsorption method After firing alumina hydrate particles (1) at 550 ° C for 1 hour, nitrogen adsorption pore distribution measuring device (BELSORB-mini, manufactured by Nippon Bell Co., Ltd.) is used. The integrated value of the relative pressure (P / Po) used was 0.38 to 0.990, the pore volume, and the peak pore diameter on the adsorption side was the average pore diameter.

Prepare a dispersion of average secondary particle size phosphorous-modified alumina hydrate particles (1) with a solid content concentration of 0.001% by weight, drop it onto a grid of a transmission electron microscope and dry it at room temperature. (TEM) Photographs were taken, the particle diameters of 50 particles were randomly measured, and the average value was defined as the secondary particle diameter with W1 as the way of bundling the particles and L1 as the arrangement in the length direction.

Preparation of coating solution (1) for forming an ink receiving layer Polyvinyl alcohol diluted with pure water to a concentration of 10% by weight as a matrix-forming component, phosphorus-modified alumina hydrate particles (1) 22.86 g (Nippon Gosei Co., Ltd.) (Product: Gohsenol GH-17R) 40 g , 1 g of aluminum acetate, 9 g of 2-propanol, and pure water were added so that the solid concentration would be 20% by weight and mixed well to form a coating solution for forming an ink receiving layer ( 1) was prepared.

Preparation of recording sheet with ink-receiving layer (1) Coating liquid (1) for forming an ink-receiving layer was prepared by using a PET film (Toray Industries, Inc .: Lumirror T-100, thickness 100 μm, refractive index 1.65, substrate transmission) The recording sheet (1) with an ink-receiving layer was prepared by coating with a bar coater at a rate of 88.0%, Haze 1.0%, and reflectance 5.1%, and drying at 60 ° C. for 20 minutes. The film thickness of the ink receiving layer at this time was 30 μm.

The total light transmittance and haze of the obtained recording sheet with ink-receiving layer (1) were measured, and the results are shown in Table 1.
The total light transmittance and haze were measured with an integrating spectrometer (manufactured by JASCO Corporation: V560).
In addition, adhesion, scratch resistance, water resistance, pore characteristics by mercury intrusion method, ink absorbability and gas barrier properties were evaluated by the following methods and evaluation criteria, and the results are shown in Table 1.

Pore properties PV (Hg) (pore volume, average pore diameter)
The receiving layer of the recording sheet with ink receiving layer (1) is peeled off from the base material, 0.2 g is measured up to a maximum pressure of 33000 psi using a mercury intrusion pore distribution measuring device (Quantachrome: Poremaster). The pore volume and average pore diameter were obtained. The results are shown in Table 1.

The surface of the recording sheet (1) with an adhesive ink-receiving layer (1) is made of 11 parallel scratches with a knife at intervals of 1 mm in length and width to make 100 squares, and a cellophane tape is adhered to this, and then the cellophane tape Adhesiveness was evaluated by classifying the number of squares remaining without peeling of the film when the film was peeled into the following four stages. The results are shown in Table 1.
Number of remaining squares: ◎
Number of remaining squares 90-99: ○
Number of remaining squares: 85 to 89: Δ
Number of remaining squares: 84 or less: ×

Scratch resistance was evaluated by reciprocating steel wool # 0000 on a scratch-resistant ink-receiving layer 10 times with a load of 50 g / cm ² and counting the number of scratches on the surface and classifying it into the following four stages. The results are shown in Table 1.
Number of scratches: ◎
Number of wounds 1 to 10: ○
Number of wounds 10-100: △
More than 100 scratches: ×

Ink absorbability Ink absorbability (1) and ink color developability (2) were evaluated by the following methods and evaluation criteria. The results are shown in Table 1.

Ink permeability (1)
Using Canon's dye printer P9000, black, which is a CMY tertiary color, is printed in a solid color at a printing density of 100%, and the surface roughness (Ra) of the printed part is measured with an ultra-deep microscope (VK-9500) manufactured by Keyence. Was measured. Similarly, the surface roughness (Ra ₀ ) of the portion where printing was not performed was measured, and the difference in surface roughness δRa (μm) = (Ra) − (Ra ₀ ) was determined and evaluated according to the following criteria. The results are shown in Table 1.

Evaluation criteria
δRa ≦ 0.15: ◎
0.15 <δRa <0.3: ○
0.3 ≦ δRa <1.0: Δ
δRa ≧ 1.0: ×

Ink coloring (2)
Using Canon's dye printer P9000, black, which is a CMY tertiary color, is printed as a single color with a solid print in 10% increments from 0% to 100%, and an integral spectrometer (manufactured by JASCO Corporation: V560) The degree of color development (brightness) measured in the Lab space was measured, and the correlation coefficient (K) between the print density (0-100%) and L (brightness%) was determined and evaluated according to the following criteria: .

Evaluation criteria
K ≧ 0.8: ◎
0.5 <K <0.8: ○
0.2 <K <0.5: Δ
K ≦ 0.2: ×

Gas barrier property The album preservation property was evaluated as gas barrier property.
First, using a Canon dye printer P9000, print the tertiary color on the recording sheet (1) with an ink receiving layer, and after drying, insert it into the vinyl bag of the album, and after 3 months at room temperature The degree of discoloration / fading was observed for the portion exposed from the vinyl-based wrapping bag and evaluated according to the following criteria. The results are shown in Table 1.

Evaluation criteria No discoloration was found: ◎
Slight discoloration was observed: ○
Obviously discoloration was observed: △
Significant discoloration was observed: ×

When the 3 cm square receiving layer of the recording sheet (1) with a water-resistant ink receiving layer was immersed in sufficient water for 30 minutes and then dried at room temperature for 24 hours, the presence or absence of traces of water was observed, and the following evaluations were made. The results were shown in Table 1.

Evaluation criteria No trace of water was found: ◎
Slight traces of water were observed: ○
Clear traces of water were found: △
The film peeled: ×

[Example 2]
Preparation of Phosphorus-Modified Alumina Hydrate Particles (2) A washed alumina hydrate gel (concentration 5 wt%) prepared in the same manner as in Example 1 except that 30 g of phosphoric acid having a concentration of 50 wt% was added to 5,000 g. Similarly, phosphorus-modified alumina hydrate particles (2) were prepared.
The composition of the obtained phosphorus-modified alumina hydrate particles (2), crystal structure by X-ray diffraction, average primary particle diameter, average secondary particle diameter, average pore diameter and pore volume were measured, and the results are shown in Table 1. .

Preparation of coating liquid for forming ink receiving layer (2) A coating liquid for forming an ink receiving layer (2) was prepared in the same manner as in Example 1 except that the phosphorus-modified alumina hydrate particles (2) were used.

Preparation of recording sheet (2) with ink-receiving layer A recording sheet (2) with an ink-receiving layer was prepared in the same manner as in Example 1 except that the coating liquid (2) for forming an ink-receiving layer was used. The recording sheet with ink-receiving layer (2) was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[Example 3]
Preparation of Phosphorus-Modified Alumina Hydrate Particles (3) Except that 5,000 g of washed alumina hydrate gel (concentration of 5% by weight) prepared in the same manner as in Example 1 was added with 200 g of phosphoric acid having a concentration of 50% by weight. Similarly, phosphorus-modified alumina hydrate particles (3) were prepared.
The composition of the obtained phosphorus-modified alumina hydrate particles (3), crystal structure by X-ray diffraction, average primary particle diameter, average secondary particle diameter, average pore diameter and pore volume were measured, and the results are shown in Table 1. .

Preparation of coating liquid for forming ink receiving layer (3) A coating liquid for forming an ink receiving layer (3) was prepared in the same manner as in Example 1 except that the phosphorus-modified alumina hydrate particles (3) were used.

Preparation of recording sheet with ink-receiving layer (3) A recording sheet with ink-receiving layer (3) was prepared in the same manner as in Example 1 except that the coating liquid for forming an ink-receiving layer (3) was used. The recording sheet with ink-receiving layer (3) was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[Example 4]
Preparation of Phosphorus-Modified Alumina Hydrate Particle (4) Phosphorus-modified alumina hydrate was similarly prepared in Example 1, except that 100 g of phosphoric acid was added and the alumina hydrate gel was aged at 90 ° C. for 10 hours. Product particles (4) were prepared.
The composition of the obtained phosphorus-modified alumina hydrate particles (4), crystal structure by X-ray diffraction, average primary particle diameter, average secondary particle diameter, average pore diameter and pore volume were measured, and the results are shown in Table 1. .

Preparation of coating liquid for forming ink receiving layer (4) A coating liquid for forming an ink receiving layer (4) was prepared in the same manner as in Example 1 except that the phosphorus-modified alumina hydrate particles (4) were used.

Preparation of recording sheet with ink-receiving layer (4) A recording sheet with ink-receiving layer (4) was prepared in the same manner as in Example 1 except that the coating liquid for forming an ink-receiving layer (4) was used. The recording sheet with ink-receiving layer (4) was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[Example 5]
Swellable resin particles (1) Preparation of dispersion As core particles, water-soluble acrylic polymer (A) having a carboxyl group at the end (manufactured by Nippon Polyurethane Industry Co., Ltd .: NIPPOLAN, WL-530, solid content concentration 40 (6.4% by weight, dispersion medium: water) was dispersed in 40 g of water, and after sufficient stirring, 1 g of ethanol was added to prepare a water-soluble acrylic polymer (A) solution having a solid content concentration of 17% by weight. did. At this time, the average particle diameter of the core particles measured by a laser light scattering method (Beckman Coulter Co., Ltd .: Coulter Model N4) was 50 nm.

  Next, 100 g of N-dimethylaminoethyl acrylate (manufactured by Mitsubishi Gas Chemical Co., Ltd.) as an ionic conductive monomer (B) containing a carbonyl group was added to a water-soluble acrylic polymer (A) solution having a solid concentration of 17% by weight. And stirring for 20 minutes at 40 ° C., followed by crosslinking (while the inner alkoxysilyl group appears outside the particle, hydrolyzes under the influence of residual water, becomes reactive, and initiates dehydration condensation) 4 g of an acrylic surfactant (manufactured by NOF Corporation: SUNBRIGHT, PA series, solid content concentration 40% by weight, dispersion medium: water, pH 8.0), which is a polyethylene glycol (PEG) derivative, is added as an agent (C), Stir at 40 ° C. for 20 minutes. At this time, the pH of the mixed solution was 7.0.

Next, after removing coarse particles and foreign matters by filtering with a filter having a pore diameter of 1 μm, a swellable resin particle (1) dispersion having a core-shell structure with a solid content concentration of 10% by weight was finally prepared by adjusting the concentration.
The obtained swellable resin particles (1) had a weight average particle diameter of 60 nm as measured by a laser light scattering method (Coulter Model N4).

Preparation of coating liquid (5) for forming ink-receiving layer 30 g of the swellable resin particle (1) dispersion obtained above and the alumina hydrate particle (1) dispersion obtained in Example 1 22.8 g, polymerizable unsaturated monomer 2-hydroxyethyl acrylate (manufactured by Nippon Kayaku Co., Ltd .: Rikagit BT-W) containing carboxylic acid as the polymerizable unsaturated monomer, 0.5 g of acrylic resin (polymer resin) Toagosei Chemical Co., Ltd .: UC-3510) 0.5g, Carbodiimide compound (Nisshinbo Co., Ltd .: Carbodilite V-02) 0.2g as a cross-linking agent, and pure water added to a 20% concentration And an ink receiving layer forming coating solution (5) was prepared.

Preparation of recording sheet with ink-receiving layer (5) A recording sheet with ink-receiving layer (5) was prepared in the same manner as in Example 1, except that the coating liquid for forming an ink-receiving layer (5) was used. The film thickness at this time was 10 μm. The recording sheet with ink-receiving layer (5) was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[Comparative Example 1]
Preparation of alumina hydrate particles (R1) Alumina hydrate particles (R1) were prepared in the same manner as in Example 1 except that phosphoric acid was not added.
The composition, crystal structure by X-ray diffraction, average primary particle size, average secondary particle size, average pore size and pore volume of the obtained alumina hydrate particles (R1) were measured and the results are shown in Table 1.

Preparation of ink-receiving layer-forming coating solution (R1) An ink-receiving layer-forming coating solution (R1) was prepared in the same manner as in Example 1 except that phosphorus-modified alumina hydrate particles (R1) were used.

Preparation of recording sheet (R1) with ink-receiving layer A recording sheet (R1) with an ink-receiving layer was prepared in the same manner as in Example 1 except that the coating liquid (R1) for forming an ink-receiving layer was used. The recording sheet with ink receiving layer (R1) was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[Reference Comparative Example 2]
Preparation of Phosphorus-Modified Alumina Hydrate Particles (R2) In the same manner as in Example 1, an alumina hydrate gel (concentration: 5% by weight) to which phosphoric acid was aged at 90 ° C. for 1 hour was prepared. Subsequently, it dried at 120 degreeC with the dryer for 24 hours, and obtained powder was crushed with the ball mill, and the phosphorus modification alumina hydrate particle | grains (R2) were prepared.

Preparation of ink-receiving layer-forming coating solution (R2) An ink-receiving layer-forming coating solution (R2) was prepared in the same manner as in Example 1 except that phosphorus-modified alumina hydrate particles (R2) were used.

Preparation of recording sheet (R2) with ink-receiving layer A recording sheet (R2) with an ink-receiving layer was prepared in the same manner as in Example 1 except that the coating liquid (R2) for forming an ink-receiving layer was used. The recording sheet with ink receiving layer (R2) was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[Comparative Example 3]
Preparation of phosphorus-modified alumina hydrate particles (R3) Except for adding 440 g of phosphoric acid having a concentration of 50% by weight to 5,000 g of a washed alumina hydrate gel (concentration 5% by weight) prepared in the same manner as in Example 1. Similarly, phosphorus-modified alumina hydrate particles (R3) were prepared.
The composition of the obtained phosphorus-modified alumina hydrate particles (R3), crystal structure by X-ray diffraction, average primary particle size, average secondary particle size, average pore size and pore volume were measured, and the results are shown in Table 1. .

Preparation of ink-receiving layer-forming coating solution (R3) An ink-receiving layer-forming coating solution (R3) was prepared in the same manner as in Example 1 except that phosphorus-modified alumina hydrate particles (R3) were used.

Preparation of recording sheet with ink-receiving layer (R3) A recording sheet with ink-receiving layer (R3) was prepared in the same manner as in Example 1 except that the coating liquid for forming an ink-receiving layer (R3) was used. The recording sheet with ink receiving layer (R3) was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[Comparative Example 4]
Preparation of Acetic Acid-Modified Alumina Hydrate Particles (R4) Same as Example 1 except that 100 g of acetic acid having a concentration of 50% by weight was added to 5,000 g of washed alumina hydrate gel (concentration 5% by weight) prepared in the same manner as in Example 1. Thus, acetic acid-modified alumina hydrate particles (R4) were prepared.
The composition of the obtained acetic acid modified alumina hydrate particles (R4), crystal structure by X-ray diffraction, average primary particle diameter, average secondary particle diameter, average pore diameter and pore volume were measured, and the results are shown in Table 1. .

Preparation of ink-receiving layer-forming coating solution (R4) An ink-receiving layer-forming coating solution (R4) was prepared in the same manner as in Example 1 except that acetic acid-modified alumina hydrate particles (R4) were used.

Preparation of recording sheet with ink receiving layer (R4) A recording sheet with ink receiving layer (R4) was prepared in the same manner as in Example 1 except that the coating liquid for forming an ink receiving layer (R4) was used. The recording sheet with ink receiving layer (R4) was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Claims (8)

Comprising phosphoric acid-modified alumina hydrate particles, a matrix-forming component and a dispersion medium,
A coating liquid for forming an ink-receiving layer, wherein the phosphoric acid-modified alumina hydrate particles have a phosphorus content in the range of 1 to 35% by weight as P ₂ O ₅ .   The coating liquid for forming an ink receiving layer according to claim 1, wherein the alumina hydrate particles are fibrous pseudo boehmite alumina.   The phosphorus-modified alumina hydrate particles have a crystallite size in the range of 30 to 150 Å, a pore volume measured by a nitrogen adsorption method of 0.8 to 2.5 ml / g, and an average pore size of 5 to 30 nm. The coating liquid for forming an ink receiving layer according to claim 1, wherein the coating liquid is in a range.   The ink according to any one of claims 1 to 3, wherein the phosphorus-modified alumina hydrate particles are obtained by spray-drying a mixed dispersion of alumina hydrate particles and a phosphorus compound. Receptor layer forming coating solution.   The matrix forming component is at least one resin selected from polyacrylic resins, polyvinyl alcohol resins, polyvinylpyrrolidone resins, urethane resins, and swellable resin particles having a core-shell structure. The coating liquid for ink receiving layer formation in any one of -4.   It consists of a base sheet and an ink receiving layer formed on the base sheet, and the ink receiving layer is formed using the ink receiving layer forming coating liquid according to any one of claims 1 to 5. A recording sheet with an ink-receiving layer.   7. The recording sheet with an ink receiving layer according to claim 6, wherein the content of the phosphorus-modified alumina hydrate particles in the ink receiving layer is in the range of 5 to 95% by weight as a solid content.   8. The pore volume measured by a mercury intrusion method of the ink receiving layer is in the range of 0.2 to 1.5 ml / g, and the average pore diameter is in the range of 10 to 60 nm. A recording sheet with an ink-receiving layer as described in 1.