JP2010214757A - 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 base material sheet with an ink receiving layer excelling in ink absorbing property and color reproducibility and excelling also in transparency, haze, adhesion to a recording medium and scratch resistance. <P>SOLUTION: A coating liquid for forming an ink receiving layer contains resin-coated metal oxide particles and matrix forming components. Coating resin of the resin-coated metal oxide particles is one or more kinds of resin selected from polyacrylic acid, polyvinyl alcohol, polyvinyl pyrrolidone and cellulose. The coating amount of resin in the resin-coated metal oxide particles is in a range of 0.5-50 mass% as a solid content (coating resin weight/coated particle weight). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ink-receiving layer-forming coating solution containing resin-coated metal oxide particles and a matrix-forming component, and a recording medium having an ink-receiving layer formed on a substrate sheet using the ink-receiving layer-forming coating solution. Related to the 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.

  Furthermore, a recording medium having a coating layer using amorphous silica or alumina hydrate having a boehmite structure has been proposed. Among them, a recording medium having a narrow pore size distribution with an average pore size of 10 to 30 angstroms of the coating layer is disclosed. There is a drawback that bleeding is generated due to insufficient absorbability.

  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, but if these particles are packed closely, large pores are formed. However, there was a drawback that the ink absorbability was poor although the scratch resistance was high.

  Patent Document 1 (Japanese Patent Laid-Open No. 5-32413) discloses a recording medium using secondary particles in which small primary particles are aggregated.

JP-A-5-32413

  However, when the present inventors examined the method described in the cited document 1, since the aggregation of particles occurs rapidly during film formation, that is, the coating liquid for forming the ink receiving layer is not stable, and the scratch resistance is high. It was difficult to satisfy the scratch resistance and the ink absorption at the same time. In addition, when a metal oxide having a large particle size is used, the pore size increases and the ink absorbency increases, but the transparency, haze, and smoothness of the ink receiving layer, the adhesion between the recording medium and the ink receiving layer, the ink It was found that the strength, scratch resistance, etc. of the receiving layer itself were liable to decrease.

  As a result of intensive studies in view of such problems, the present inventors have used a resin-coated metal oxide particle used in the ink receiving layer, so that in the ink receiving layer forming coating liquid. The particle dispersibility is improved, the stability of the coating liquid is remarkably improved, and the ink receiving layer formed using such an ink receiving layer forming coating liquid is excellent in ink absorption and color reproducibility, The present invention has been completed by finding excellent transparency, haze, adhesion to a recording medium, and scratch resistance.

The configuration of the present invention is as follows.
[1] A coating liquid for forming an ink receiving layer comprising resin-coated metal oxide particles and a matrix-forming component.
[2] The coating liquid for forming an ink receiving layer according to [1], wherein the coating resin of the resin-coated metal oxide particles is at least one resin selected from polyacrylic acid, polyvinyl alcohol, polyvinylpyrrolidone, and celluloses.
[3] The ink according to [1] or [2], wherein a resin coating amount in the resin-coated metal oxide particles is in a range of 0.5 to 50% by mass as a solid content (coating resin weight / coating particle weight). Receptor layer forming coating solution.
[4] The metal oxide particles are at least one selected from the group consisting of MgO, TiO ₂ , SiO ₂ , ZrO ₂ , Al ₂ O ₃ , Sb ₂ O ₅ , ZnO, and composite oxides thereof. [1] to [3] A coating solution for forming an ink receiving layer.
[5] The resin-coated metal oxide particles are single particles (primary particles) and / or aggregate particles (secondary particles) of two or more single particles, and the average primary particle diameter (D ₁ ) is 10 to 5000 nm. in the range of, for aggregate particle, the average particle diameter (secondary particle diameter (D ₂₎ is in the range of 20~10,000nm [1] ~ ink receiving layer coating solution of [4].

[6] The ratio (D ₂ ) / (D ₁ ) between the average secondary particle diameter (D ₂ ) and the average primary particle diameter (D ₁ ) is in the range of ₁ to 20; Coating liquid for forming an ink receiving layer.
[7] The coating liquid for forming an ink receiving layer according to [1] to [6], wherein the matrix forming component is at least one resin selected from polyacrylic resins, polyvinyl alcohol resins, and polyvinylpyrrolidone resins.
[8] The ink-receiving layer-forming coating liquid according to [1] to [7], wherein the matrix-forming component is resin fine particles having an average particle diameter in the range of 5 nm to 20 μm.
[9] The ink according to [1] to [8], wherein the resin fine particles are at least one selected from acrylic cross-linked copolymer fine particles, urethane cross-linked copolymer fine particles, and acrylic-urethane cross-linked copolymer fine particles. Receptor layer forming coating solution.
[10] After the resin fine particles have added (a) a coating resin to the metal oxide particle dispersion,
(B) The ion exchange resin is obtained by adjusting the anion concentration in the dispersion so as to be 1 to 10,000 ppm per unit weight of the metal oxide particles [1] to [ The coating liquid for forming an ink receiving layer according to 9].
[11] A substrate sheet and an ink receiving layer formed on the substrate sheet, and the ink receiving layer was formed using the ink receiving layer forming coating liquid of [1] to [10] A recording sheet with an ink-receiving layer.

  According to the present invention, since the metal oxide particles coated with a resin having a high affinity with the matrix-forming component are included, the particles are not aggregated in the ink-receiving layer-forming coating solution, and the ink absorbability For forming an ink receiving layer that is excellent in color reproducibility and can be suitably used for forming an ink receiving layer excellent in transparency, haze, surface smoothness, adhesion to a recording medium, strength, scratch resistance, etc. A recording sheet with a coating liquid and an ink receiving layer can be provided.

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 is characterized by comprising resin-coated metal oxide particles and a matrix-forming component.

Resin-coated metal oxide particles In the resin-coated metal oxide particles used in the present invention, the surface of the metal oxide particles is coated with a resin. The resin-coated metal oxide particles may be either single particles (hereinafter referred to as primary particles in the present invention) or aggregated particles (hereinafter referred to as secondary particles in the present invention). Here, the single particles are those in a non-aggregated state. Specifically, the particles are mono-dispersed in a dispersion medium and coated with a resin, and the non-aggregated state is maintained even after coating. Aggregated particles may be two or more aggregate particles of primary particles, or metal oxide aggregate particles coated with a resin.

As the metal oxide particles, conventionally known metal oxide particles used for the ink receiving layer can be used. Examples of the metal oxide include one or more particles selected from MgO, TiO ₂ , SiO ₂ , ZrO ₂ , Al ₂ O ₃ , Sb ₂ O ₅ , ZnO, and composite oxides thereof.

  The metal oxide particles can be appropriately selected and used depending on the desired properties of the recording sheet with an ink receiving layer. For example, the metal oxide fine particles used for the ink receiving layer provided on the PET substrate generally have a refractive index of about Metal oxide fine particles adjusted to about 1.55 to 1.60 are used. Moreover, when using paper as a base material, the refractive index of metal oxide fine particles can be used without any particular limitation. In addition, a refractive index can be adjusted with the refractive index and particle diameter of metal oxide itself to be used.

  The average primary particle diameter of the metal oxide particles before coating is preferably in the range of about 5 to 5000 nm, more preferably 10 to 3000 nm. When the average particle diameter is within this range, an ink receiving layer excellent in transparency and ink absorbability can be formed. If the average particle diameter of the metal oxide particles is too small, the pore volume of the pores formed as the particle gaps may be small and the ink absorbability of the ink receiving layer may be insufficient, and if the average particle diameter is too large. The transparency of the ink receiving layer is low, and the strength and adhesion to the substrate may be insufficient.

(Coating resin)
As the coating resin for the resin-coated metal oxide particles, one or more resins selected from polyacrylic acid resins, polyvinyl alcohol resins, polyvinyl pyrrolidone resins, and celluloses are used.

Among these, polyacrylic acid resins, polyvinyl alcohol resins, and polyvinyl pyrrolidone resins are preferable.
These resins can be uniformly coated on metal oxide particles, have high affinity with matrix forming components and polar solvents used in the ink receiving layer forming coating liquid described later, and the resulting resin-coated metal oxide Since the product particles are excellent in dispersibility and excellent in the stability of the coating solution, they can be suitably used.

  The coating resin preferably has a molecular weight (polystyrene equivalent molecular weight) in the range of 1000 to 1,000,000, more preferably 1,000 to 500,000. When the molecular weight is within this range, the steric hindrance repulsive force is high when bonded to the particle surface, the concentration stability is high when the solvent is volatilized, and aggregation is difficult. If the molecular weight of the coating resin is too small, the side chain may be short even when bonded to the particle surface, resulting in insufficient steric hindrance repulsion, or low affinity with the matrix component and aggregation. is there. If the molecular weight of the coating resin is too high, it tends to be difficult to laminate on the surface of the metal oxide particles.

  The resin coating amount in the resin-coated metal oxide particles is preferably in the range of 0.5 to 50% by mass, more preferably 1 to 30% by mass as the solid content (coating resin weight / coating particle weight). If the coating amount is within this range, resin-coated metal oxide particles having high affinity with the matrix component and polar solvent and excellent dispersibility can be obtained, and the coating solution for forming an ink receiving layer using this is stable. Excellent in properties. If the coating amount is small, the dispersibility in the coating solution for forming the ink receiving layer and the stability of the coating solution are insufficient, and the resulting ink receiving layer also has low transparency, high haze, and low scratch resistance. There is. In addition, even if the coating amount is too large, it is difficult to laminate (adhesion, adsorption) of the resin to the particles, so it is difficult to increase the amount beyond the above range. Dispersibility, coating solution stability, transparency of the resulting ink-receiving layer, haze, adhesion to the substrate, etc. are not further improved. The effect to be used, for example, a desired refractive index and a desired pore volume may not be adjusted.

The average primary particle diameter of the resin-coated metal oxide particles (D ₁₎ is 10～5,000Nm, more preferably in the range of 20～3,000Nm. However, it is larger than the average particle diameter of the metal oxide particles before resin coating.

When the average particle diameter (D ₁ ) is in this range, the pore volume is sufficient, and transparency, strength, and adhesion to the substrate can be enhanced. If the average particle diameter (D ₁ ) is too small, the pore volume between particles is small and the ink absorbability of the ink receiving layer may be low. On the other hand, if the average particle diameter (D ₁ ) is too large, the transparency, strength, adhesion to the substrate and the like of the ink receiving layer may be insufficient.

When the resin-coated metal oxide particles are agglomerated particles, the average particle diameter (average secondary particle diameter (D ₂₎ is 20～10,000Nm, more preferably in the range of 30~6,000nm .D ₂ Is within the above range, the transparency, strength, and adhesion to the substrate of the ink-receiving layer can be improved, and those having an average secondary particle diameter (D ₂ ) smaller than the lower limit are substantially single particles. If the ink receiving layer is too large, the transparency, strength, adhesion to the substrate and the like of the ink receiving layer may be insufficient.

The ratio (D ₂ ) / (D ₁ ) between the average primary particle diameter (D ₁ ) and the average secondary particle diameter (D ₂ ) is preferably in the range of 1-20, more preferably 2-15. Within this range, the ink receptivity is high, and the transparency, haze, strength, and adhesion to the substrate of the ink receptive layer can be increased. In addition, (D ₂ ) / (D ₁ ) = 1 means the single grain and never becomes less than 1. When (D ₂ ) / (D ₁ ) is too large, the aggregation of the particles is large, and the transparency, haze, strength, adhesion to the substrate, etc. of the ink receiving layer become insufficient, although it varies depending on the particle diameter. There is.

In the present invention, the average primary particle diameter (D ₁ ) is obtained as an average value by taking a transmission electron micrograph (TEM), observing the aggregation state of the particles and measuring the particle diameter of 100 primary particles. be able to.

The average secondary particle diameter (D ₂ ) can be measured by a light scattering method.
The thickness of the resin coating layer of such resin-coated metal oxide particles is preferably in the range of approximately 0.5 to 5 nm, more preferably 1 to 3 nm.

  If the thickness of the resin coating layer is within the above range, the dispersibility in the ink-receiving layer-forming coating solution is high, the stability of the coating solution is improved, and the effect of using specific metal oxide particles themselves is hindered. Therefore, the desired refractive index and desired pore volume can be adjusted.

  If the thickness of the resin coating layer is too thin, the resin coating effect may be insufficient, i.e., the dispersibility in the ink-receiving layer-forming coating solution, and the effect of improving the stability of the coating solution may be insufficient. Even if it is too thick, the effect of improving the dispersibility in the coating liquid for forming the ink-receiving layer and the stability of the coating liquid is not further improved, and specific metal oxide particles are added as the thickness of the resin coating layer increases. The effect to be used, for example, a desired refractive index and a desired pore volume may not be adjusted.

The thickness of such a resin coating layer is measured by (1) (average primary particle diameter (D ₁ ) −average particle diameter of oxide particles) / 2 in the case of single particles. In addition, in the case of (2) single agglomerated particles, the same as the above single particles, and (3) in the case of resin-coated particles of metal oxide agglomerated particles (average secondary particle diameter (D ₂ ) −average The average particle diameter of the metal oxide aggregated particles) / 2.

  Such resin-coated metal oxide particles used in the present invention are produced by using the above-described resin and metal oxide particles by a conventionally known method such as a mechanochemical method, a plasma polymerization method, a plasma-graft polymerization method, or the like. Can do. Specifically, JP-A-3-163172, JP-A-6-336558, JP-A-6-49251, JP-A-2000-143230, JP-A-7-118123, JP-A-2003-63932. It can be manufactured in accordance with the method disclosed in the Japanese Patent Publication.

  However, in the conventional method for producing particles coated with a resin, it is difficult to uniformly coat the resin on individual particles, and the resin is coated on particles in which several or more metal oxide particles are aggregated. However, the resin may be dissolved in the solvent of the coating solution, and the dispersibility and stability in the coating solution for forming the ink receiving layer may not be sufficiently obtained. In some cases, scratch resistance or the like may be insufficient, and the following method is recommended in the present invention.

(Method for producing resin-coated metal oxide particles)
The method for producing resin-coated metal oxide particles that can be suitably employed in the present invention includes the following steps.
(A) A step of adding a predetermined amount of a coating resin to a metal oxide particle dispersion having a predetermined solid content concentration (b) An anion concentration is 1 to 10,000 ppm per unit weight of the metal oxide particles in the ion exchange resin. So that ions are removed.

(A) Process A coating resin as described above is added to the metal oxide particle dispersion.
The metal oxide particles and the coating resin are as described above.

As a dispersion medium for the metal oxide particle dispersion, water, alcohols, glycols, and mixed solvents thereof are used.
The coating resin is added so that the coating amount of the resulting resin-coated metal oxide particles is in the above-described range as a solid content. Usually, the added coating resin forms a coating layer as it is.

The concentration of the metal oxide particle dispersion is not particularly limited, but from the viewpoint of workability and efficiency, it is desirable that the concentration be in the range of 0.5 to 45 mass%, preferably 1 to 40 mass%.
The concentration of the dispersion after adding the coating resin to the metal oxide particle dispersion is preferably in the range of 1 to 50 mass%, more preferably 1 to 40 mass% as the solid content.

If the concentration of the dispersion after addition of the resin is low, the production efficiency and mass productivity in step (b) are poor, which is not economical, and if the concentration of the dispersion is too high, excessively agglomerated particles are obtained. (D ₂ ) / (D ₁ ) becomes too high, or the average secondary particle diameter (D ₂ ) becomes too large, and the transparency, haze, strength, and adhesion to the substrate of the ink receiving layer obtained. Etc. may be insufficient.

  In the metal oxide particle dispersion, it is preferable that an anion corresponding to 500 to 100,000 ppm, more preferably 1,000 to 50,000 ppm per unit weight of the metal oxide particles is present.

Usually, as anions present in the dispersion, SO ₄ ²⁻ , NO ₃ ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , F ⁻ , PO ₄ ³⁻ , and oxalic acid, phthalic acid, tartaric acid, citric acid, malein Examples thereof include carboxylate ions such as acid, acetic acid and formic acid. These anions are contained in the metal oxide particles or are added as necessary. By including such an anion, the anion is adsorbed to the entire metal oxide particles, and a coating resin is added. Then, when the anion exchange resin is treated, the anion is desorbed from the surface and coated. It is considered that the resin can be coated from the entire particle surface when the resin for resin is adsorbed on the entire particle surface in the form of exchange with anions and then polymerized.

If the amount of the anion present is small, the amount of ions on the surface of the metal oxide particles may be small depending on the molecular weight of the resin, and the resin may be insufficiently adsorbed on the surface of the metal oxide particles.
If the amount of the anion is too large, the metal oxide particles may aggregate.

  Next, the pH of the dispersion liquid after addition of the resin varies depending on the metal oxide particles, but is set in a range in which the metal oxide particles do not aggregate or dissolve. It is desirable to evaluate and set it to the range of about 3 to 11, more preferably 4 to 10.5. When the pH is not within the above range, the metal oxide particles may aggregate or dissolve, and the desired resin-coated metal oxide particles may not be obtained.

The pH of the dispersion is adjusted using an inorganic acid such as nitric acid, hydrochloric acid or sulfuric acid, an organic acid such as formic acid, acetic acid or citric acid, or an alkali such as sodium hydroxide, potassium hydroxide or ammonia.
Moreover, the dispersion can adjust the anion concentration as necessary, and the anion concentration may be adjusted by adding the salt or acid containing the anion as described above.

By this step (a), a dispersion in which the metal oxide fine particles adsorbing anions and the resin are uniformly and stably dispersed can be obtained.
The temperature of the dispersion at this time in step (a) is preferably in the range of 10 to 60 ° C. Outside this temperature range, problems such as increased dissolution of particle components, reduced stability, non-uniform resin coating, and (D ₂ ) / (D ₁ ) becoming too high. Or the resin coating may be non-uniform.

(B) Step The dispersion obtained in step (a) is then subjected to ion exchange resin so that the anion concentration is 1 to 10,000 ppm, more preferably 5 to 7,000 ppm per unit weight of the metal oxide particles. Adjust as follows. The anion is derived from the anion contained in the particles or the anion added as described above. By adjusting this anion to a specific range, the surface of the metal oxide particle is coated with the resin.

  It should be noted that the anion is preferably not present completely but present in a certain amount. If an anion is present in the above range, the electric repulsion works, or the dispersion is stably dispersed. If there are too few anions, the electric repulsion tends to be reduced and tends to aggregate. Even if the amount is too large, salting out tends to occur and thus tends to aggregate. If there are too many anions, the adhesion, transparency, strength, and the like of the ink receiving layer obtained by saponifying the matrix may be insufficient.

As the ion exchange resin, an anion exchange resin or a both ion exchange resin is used.
The ion exchange resin treatment coats the resin with a decrease in the anion concentration, but the mechanism is not clear, but the anion on the surface of the original metal oxide particles is replaced with the resin so that the ion exchange resin is anion. It is considered that the resin is stacked on the surface of the metal oxide particles while trapping ions.

Although the usage-amount of an ion exchange resin changes also with the ion exchange capacity of an ion exchange resin, the range of 1-300 mass% with respect to a metal oxide particle, Furthermore, the range of 2-100 mass% is preferable.
At this time, when the treatment is performed with an ion exchange resin, the pH of the dispersion is lowered, and the pH after the treatment with the ion exchange resin is in a range of 2 to 10, more preferably 2 to 9.5.

  If the pH after treatment is too low, the ion concentration may be low even if it can be coated with a resin, and the metal oxide particles may aggregate or dissolve, and the ink used for the ink receiving layer forming coating liquid described later may be used. When the receptor layer is formed, it rapidly aggregates when the polar solvent volatilizes, and the adhesion, transparency, strength, etc. may be insufficient. If the pH after treatment is too high, when used in a coating solution for forming a receiving layer, which will be described later, the matrix components are saponified, and the resulting ink receiving layer has insufficient adhesion, transparency, strength, etc. to the substrate. It may become.

Usually, in the step (b), the pH is lowered by about 0.5 to 7.5, preferably about 1 to 6 before and after the ion exchange resin treatment.
In this way, resin-coated metal oxide particles that can be suitably used in the present invention can be obtained.

  Without treatment with an ion exchange resin, the anion adsorbed on the metal oxide particle surface does not easily leave, and even if a coating resin is added, the non-resining resin does not adsorb on the entire particle surface, so the entire particle surface In some cases, resin coating may not be possible.

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 conventionally known thermosetting resin, thermoplastic resin, or the like can be used. 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.

The matrix forming component may be the same as or different from the resin that forms the resin coating layer.
These resins may be emulsion resins, water-soluble resins, and hydrophilic resins. Further, 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. Further, a vinyl group, a urethane group, an epoxy group, it is possible to employ (meth) acryloyl group, a polyfunctional (meth) acrylic acid ester resin and emulsion-based particles having a functional group such as CF ₂ groups also suitably.

  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 for metal oxides, excellent transparency, haze, dye fixing property, and the like, and excellent scratch resistance.

  Furthermore, in the present invention, it is preferable to use resin fine particles having an average particle diameter in the range of 5 nm to 20 μm, more preferably 10 nm to 10 μm, as the matrix forming component. The resin fine particles include a resin emulsion.

  When resin fine particles are used, acrylic cross-linked copolymer fine particles, urethane cross-linked copolymer fine particles, acrylic-urethane cross-linked copolymer fine particles, and mixtures thereof are preferred. When such resin fine particles are used, since the resin is fine particles, there are pores due to particle gaps, and since the resin fine particles have swellability, the resin fine particles in the ink receiving layer do not absorb ink. It swells when absorbed and has excellent ink absorbency and acceptability.

  Further, by using the resin fine particles having the average particle diameter, the pore volume and pore diameter of the obtained ink receiving layer can be adjusted, and the ink absorbability, the drying speed, etc. can be adjusted or improved. .

When the average particle size of the resin fine particles is less than 10 nm, the pore volume of the ink receiving layer is small, and the ink absorbability and dye fixability may be insufficient.
When the average particle diameter of the resin fine particles exceeds 20 μm, the pore volume increases, but the transparency of the ink receiving layer may be lowered or haze may be increased.

  Furthermore, the resin fine particles preferably have pores having an average diameter in the range of approximately 1 to 20 nm. With such pores, although the pore volume of the ink receiving layer is increased, the ink absorbability is improved and the dye fixing property is improved without decreasing transparency or increasing haze. There is a case.

Coating solution composition The total solid concentration of the coating solution for forming an ink receiving layer is preferably in the range of 1 to 60 mass%, more preferably 2 to 50 mass%. Within this range, an ink receiving layer having a desired thickness can be uniformly formed by a single application, which is economical. If the total solid content concentration is too low, a predetermined film thickness may not be obtained by a single application, and therefore it is necessary to repeat application and drying, which may not be economical. If the total solid concentration is too high, the thickness of the resulting receiving layer tends to be non-uniform.

  The concentration of the resin-coated metal oxide particles in the ink-receiving layer-forming coating solution is such that the content of the resin-coated metal oxide particles in the obtained ink-receiving layer is 5 to 95% by mass, further 10 The concentration is preferably in the range of ˜90 mass%.

  When the content of the resin-coated metal oxide particles is in the above range, a sufficient pore volume can be obtained, the ink absorption of the ink receiving layer, the dye fixing property is high, the adhesion to the substrate, the strength, and the transparency Ink-receiving layer having excellent properties, haze, scratch resistance and the like can be formed. If the content of the resin-coated metal oxide particles is small, a sufficient pore volume cannot be obtained due to an increase in the matrix-forming components, and the ink absorption property of the ink receiving layer and the dye fixing property may be insufficient. In addition, if the content of the resin-coated metal oxide 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 liquid is such that the content of the matrix component in the resulting ink-receiving layer is in the range of 5 to 95% by mass, more preferably 10 to 90% by mass, based on the total solid content. It is preferable that the concentration is as follows.

Polar solvent The polar solvent used in the present invention is not particularly limited as long as it can dissolve or disperse the matrix-forming component and, if necessary, the polymerization initiator used and uniformly disperse the resin-coated metal oxide particles described above. Conventionally known solvents 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.

  The above coating solution for forming the receiving layer 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, curtain coating. The receptor layer can be formed by applying to a substrate by a known method such as a method or a spray method, drying, and curing by a conventional method such as ultraviolet irradiation or heat treatment.

[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.

The same resin-coated metal oxide particles as those described above are used.
The content of the resin-coated metal oxide fine particles in the ink receiving layer is preferably from 5 to 95% by mass, more preferably from 10 to 90% by mass, based on the total solid content. If the content of the resin-coated metal oxide particles is in the above range, a sufficient pore volume can be obtained, the ink absorption of the ink receiving layer and the dye fixing property are high, adhesion to the substrate, strength, and transparency. Ink-receiving layer having excellent properties, haze, scratch resistance and the like can be formed.

  If the content of the resin-coated metal oxide fine particles is small, the ink absorbency may be insufficient due to the small amount of particles, and if it is too large, the matrix component is small, adhesion to the substrate, transparency, Haze, scratch resistance, etc. may be insufficient.

  The matrix component is derived from the organic resin matrix forming component described above. In the thermosetting resin matrix forming component, the 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 content of the matrix component in the ink receiving layer is preferably in the range of 5 to 95% by mass, more preferably 10 to 90% by mass as the solid content.
When the content of the matrix component is in the above range, an ink receiving layer having high adhesion to the substrate, transparency, haze, scratch resistance, etc. and excellent ink absorbability can be formed.

  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 is in this range, the ink absorbency is high, and no cracks or curling (curving or warping) occur.

  If the ink receiving layer is too thin, the ink absorbency may be insufficient, and if it is too thick, it is difficult to obtain it by a single coating, and it is economical to perform multiple coatings. In addition to being a problem, the ink receiving layer may be cracked or curled.

  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.

The method for recording by applying ink to the recording sheet with an ink-receiving layer according to the present invention is not particularly limited, but usually an inkjet recording method is preferred, and this recording method effectively separates the ink from the nozzles. Any method may be used as long as it can apply ink to the recording medium.
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 resin-coated metal oxide particle (B-1) dispersion Alumina hydrate particles (manufactured by JGC Catalysts & Chemicals Co., Ltd .: AS-5, solid content concentration 20% by mass, average particle size 20 nm, acetic acid concentration 33,000 ppm In addition, 2 g of polyvinylpyrrolidone (Tokyo Kasei Co., Ltd .: K-15, average molecular weight 10,000) is added to 100 g of water dispersion medium), and then 10 g of amphoteric ion exchange resin (Mitsubishi Chemical: SMNUPB) is added, After stirring for 3 hours at 50 ° C., the ion exchange resin was separated. The pH at that time was 3.5. Thereafter, the resultant was concentrated using an ultra-fine membrane to obtain a resin-coated metal oxide particle (B-1) dispersion having a solid concentration of 20% by mass.

The transmission primary electron micrograph (TEM) of the resin-coated metal oxide particles (B-1) was photographed, and the average primary particle diameter (D ₁ ) measured for 100 particles was 30 nm. The light scattering method The average secondary particle diameter (D ₂ ) measured by (Otsuka Electronics Co., Ltd .: PER-III) was 200 nm.

Ink receiving layer coating solution (C-1) resin obtained above obtained in Preparation above coated metal oxide particles (B-1) pure water to a concentration of 10 mass% dispersion 60 g, as a matrix-forming component 30 g of polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Co., Ltd .: Gohsenol GH-17R), 1 g of aluminum acetate and 9 g of 2-propanol were mixed thoroughly to prepare a coating solution (C-1) for forming an ink receiving layer. did.
The stability of the ink receiving layer forming coating solution (C-1) was evaluated by the following methods and evaluation criteria, and the results are shown in the table.

Stability evaluation The ink receiving layer forming coating solution (C-1) was placed in a thermostatic bath at 80 ° C. for 12 hours, and then the coating solution was visually free from agglomerates and the liquidity did not change. The stability evaluation was performed by ◯ for the rising, Δ for the partial agglomeration and sedimentation confirmed, and x for the aggregation and sedimentation.

Preparation of recording sheet with ink-receiving layer (D-1) Coating liquid (C-1) for forming an ink-receiving layer was prepared by using PET film (Toray Industries, Inc .: Lumirror T-100, thickness 100 μm, refractive index 1.65. , Substrate transmittance 88.0%, Haze 1.0%, reflectance 5.1%), coated with a bar coater, dried and cured at 70 ° C. for 1 minute, and recording sheet with ink receiving layer (D -1) was prepared. 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 an ink receiving layer (D-1) were measured, and the results are shown in Table 1.
The total light transmittance and haze were measured by a haze meter (Nippon Denshoku Co., Ltd .: NDH2000).
In addition, adhesion and scratch resistance were evaluated by the following methods and evaluation criteria, and the results are shown in Table 1.

The surface of the recording sheet (D-1) with adhesive ink-receiving layer was made with 11 parallel scratches with a knife at intervals of 1 mm in length and width to make 100 squares, and cellophane tape was adhered to it, Adhesiveness was evaluated by classifying the number of cells remaining without peeling of the coating when the cellophane tape was peeled into the following four stages. The results are shown in the table.
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.
Number of scratches: ◎
Number of wounds 1 to 10: ○
Number of wounds 10-100: △
More than 100 scratches: ×

Ink absorbability The ink absorptivity was examined by touching the recording part with a finger on the dry state of ink on the surface of the ink receiving layer after black (Bk) was solid-printed in a single color with an EPSON printer PM920C. The amount of ink in single color printing was 100%.
When the ink amount is 300% or more, the ink adheres to the finger: ◎
When the ink amount is 200 to less than 300% and the ink adheres to the finger: ○
When the ink amount is less than 100 to 200% and the ink adheres to the finger: Δ
When the ink amount is less than 100% and the ink adheres to the finger: ×

[Example 2]
Preparation of coating liquid (C-2) dispersion for ink-receiving layer formation 52.5 g of resin-coated metal oxide particle (B-1) dispersion prepared in the same manner as in Example 1, and emulsion-based acrylic as a matrix-forming component Polymerization fine particles (Daido Kasei Kogyo Co., Ltd .: Vinizol 1005, concentration 35 mass%) 12.85 g, aluminum acetate 1 g, 2-propanol 10 g, and pure water 23.65 g were mixed thoroughly to obtain a receiving layer forming coating solution ( C-2) was prepared. The stability of the coating solution was evaluated, and the results are shown in the table.

Preparation of recording sheet with ink receiving layer (D-2) Recording sheet with ink receiving layer (D-2) was prepared in the same manner as in Example 1 except that the coating liquid (C-2) for forming an ink receiving layer was used. ) Was prepared. The thickness of the receiving layer at this time was 15 μm.
The recording sheet with an ink-receiving layer (D-2) was measured for total light transmittance, haze, adhesion, scratch resistance, and ink absorbability. The results are shown in Table 1.

[Example 3]
Preparation of coating liquid for forming ink receiving layer (C-3) 52.5 g of a resin-coated metal oxide particle (B-1) dispersion prepared in the same manner as in Example 1, and emulsion-based acrylic-urethane as a matrix forming component Polymerization fine particles (Daido Kasei Kogyo Co., Ltd .: Vinizol 7492PR-C, concentration 40% by mass) 11.25 g, aluminum acetate 1 g, 1-butanol 10 g, and pure water 25.25 g are mixed well to form a receiving layer. A liquid (C-3) was prepared. The stability of the coating solution was evaluated, and the results are shown in the table.

Preparation of recording sheet with ink receiving layer (D-3) Recording sheet with ink receiving layer (D-3) was prepared in the same manner as in Example 1 except that the coating liquid (C-3) for forming an ink receiving layer was used. ) Was prepared. The thickness of the receiving layer at this time was 15 μm.
The total light transmittance, haze, adhesion, scratch resistance, and ink absorbability of the obtained recording sheet with an ink receiving layer (D-3) were measured, and the results are shown in Table 1.

[Example 4]
Preparation of Resin Coated Metal Oxide Particle (B-4) Dispersion Silica fine particles (manufactured by JGC Catalysts & Chemicals Co., Ltd .: silica microbead P-500, average particle size 1500 nm) using pure water and nitric acid with a SiO ₂ concentration of 20 It diluted so that it might become mass% and nitrate ion 20,000ppm. 1.59 g of polyacrylic acid (Aldrich: average molecular weight: 5,000, solid content: 63% by mass) was added to 100 g of this dispersion, and then 10 g of amphoteric ion exchange resin (Mitsubishi Chemical: SMNUPB) was added. After stirring for a period of time, the ion exchange resin was separated. The pH at that time was 4.0. Subsequently, it concentrated with the rotary evaporator and obtained the resin coating metal oxide particle (B-4) dispersion liquid with a solid content concentration of 20 mass%.

Preparation of coating solution (C-4) for forming an ink-receiving layer 52.5 g of the resin-coated metal oxide particle (B-4) dispersion obtained above was diluted with pure water to a concentration of 10% by mass as a matrix-forming component. 45 g of polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Co., Ltd .: Gohsenol GH-17R), 1 g of aluminum acetate and 1.5 g of pure water were sufficiently mixed to prepare a coating liquid (C-4) for forming an ink receiving layer. The stability of the coating solution was evaluated, and the results are shown in the table.

Preparation of recording sheet with ink receiving layer (D-4) Recording sheet with ink receiving layer (D-4) was prepared in the same manner as in Example 1 except that the coating liquid (C-4) for forming an ink receiving layer was used. ) Was prepared. At this time, the thickness of the receiving layer was 40 μm.
The total light transmittance, haze, adhesion, scratch resistance, and ink absorptivity of the obtained recording sheet with an ink receiving layer (D-4) were measured, and the results are shown in Table 1.

[Example 5]
Preparation of Resin Coated Metal Oxide Particles (B-5) Dispersion Silica fine particles (manufactured by JGC Catalysts & Chemicals Co., Ltd .: silica microbead P-500, average particle size 1500 nm) using pure water and nitric acid with a SiO ₂ concentration of 20 It diluted so that it might become mass% and nitrate ion 20,000ppm. To 100 g of this dispersion, 6.35 g of polyacrylic acid (manufactured by Aldrich: average molecular weight 5,000, solid content concentration 63 mass%) is added, and then 10 g of amphoteric ion exchange resin (manufactured by Mitsubishi Chemical: SMNUPB) is added. After stirring at 0 ° C. for 3 hours, the ion exchange resin was separated. The pH at that time was 3.8. Subsequently, it concentrated with the rotary evaporator and obtained the resin coating metal oxide particle (B-5) dispersion liquid with a solid content concentration of 20 mass%.

Preparation of coating liquid for forming ink-receiving layer (C-5) 52.5 g of the resin-coated metal oxide particle (B-5) dispersion obtained above was diluted with pure water to a concentration of 10% by mass as a matrix-forming component. 45 g of polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Co., Ltd .: Gohsenol GH-17R), 1 g of aluminum acetate and 1.5 g of pure water were sufficiently mixed to prepare a coating liquid (C-5) for forming an ink receiving layer. The stability of the coating solution was evaluated, and the results are shown in the table.

Preparation of recording sheet with ink receiving layer (D-5) Recording sheet with ink receiving layer (D-5) was prepared in the same manner as in Example 1 except that the coating liquid (C-5) for forming the ink receiving layer was used. ) Was prepared. At this time, the thickness of the receiving layer was 40 μm.
The recording sheet with ink receiving layer (D-5) thus obtained was measured for total light transmittance, haze, adhesion, scratch resistance, and ink absorbability. The results are shown in Table 1.

[Example 6]
Preparation of Resin Coated Metal Oxide Particles (B-6) Dispersion Silica fine particles (manufactured by JGC Catalysts & Chemicals Co., Ltd .: silica microbead P-500, average particle diameter 1500 nm) using pure water and nitric acid with a SiO ₂ concentration of 20 It diluted so that it might become mass% and nitrate ion 20,000ppm. 15.9 g of polyacrylic acid (manufactured by Aldrich: average molecular weight 5,000, solid content concentration 63 mass%) is added to 100 g of this dispersion, and then 10 g of amphoteric ion exchange resin (manufactured by Mitsubishi Chemical: SMNUPB) is added. After stirring at 0 ° C. for 3 hours, the ion exchange resin was separated. The pH at that time was 3.6. Subsequently, it concentrated with the rotary evaporator and obtained the resin coating metal oxide particle (B-6) dispersion liquid of solid content concentration 20 mass%.

Ink receiving layer coating solution (C-6) a resin obtained in Preparation above coated metal oxide particles (B-6) dispersion liquid 52.5 g, polyvinyl diluted with pure water to a concentration of 10 mass% as the matrix-forming component An ink receiving layer forming coating solution (C-6) was prepared by thoroughly mixing 45 g of alcohol (manufactured by Nippon Synthetic Chemical Co., Ltd .: Gohsenol GH-17R), 1 g of aluminum acetate, and 1.5 g of pure water. The stability of the coating solution was evaluated, and the results are shown in the table.

Preparation ink-receiving layer-forming coating liquid of the recording sheet having an ink-receiving layer (D-6) (C- 6) is similar to Example 1 of the ink-receiving layer with the recording sheet by the method except for using (D-6 ) Was prepared. At this time, the thickness of the receiving layer was 40 μm.
The total light transmittance, haze, adhesion, scratch resistance and ink absorptivity of the obtained recording sheet with an ink receiving layer (D-6) were measured, and the results are shown in Table 1.

[Example 7]
Preparation of dispersion of resin-coated metal oxide particles (B-7) Silica / alumina fine particles (Zeolist Co., Ltd .: ZSM-5 [model number CVB3024E], SiO ₂ / Al ₂ O ₃ (mol / mol) = 30, average The particle diameter of 500 nm) was diluted with pure water and sulfuric acid so that the SiO ₂ .Al ₂ O ₃ concentration was 20 mass% and the sulfate ion was 15,000 ppm. To 100 g of this dispersion, 2 g of polyvinyl pyrrolidone (Kanto Chemical Co., Ltd .: K-60, average molecular weight of 10,000,000) was added, and then 10 g of amphoteric ion exchange resin (Mitsubishi Chemical Co., Ltd .: SMNUPB) was added and stirred at 50 ° C. for 3 hours. Thereafter, the ion exchange resin was separated. The pH at that time was 4.2. Thereafter, the resultant was concentrated by a rotary evaporator to obtain a resin-coated metal oxide particle (B-7) dispersion having a solid content of 20% by mass.

Preparation of coating liquid for forming ink-receiving layer (C-7) 52.5 g of the resin-coated metal oxide particle (B-7) dispersion obtained above was diluted with pure water to a concentration of 10% by mass as a matrix-forming component. 45 g of polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Co., Ltd .: Gohsenol GH-17R), 1 g of aluminum acetate, and 1.5 g of pure water were sufficiently mixed to prepare a coating solution (C-7) for forming a receiving layer. The stability of the coating solution was evaluated, and the results are shown in the table.

Preparation of recording sheet with ink receiving layer (D-7) Recording sheet with ink receiving layer (D-7) was prepared in the same manner as in Example 1 except that the coating liquid for forming an ink receiving layer (C-7) was used. ) Was prepared. The thickness of the receiving layer at this time was 20 μm.
The recording sheet with ink receiving layer (D-7) thus obtained was measured for total light transmittance, haze, adhesion, scratch resistance, and ink absorbability. The results are shown in Table 1.

[Example 8]
Preparation of Resin Coated Metal Oxide Particles (B-8) Dispersion Silica / Alumina Fine Particles Silica / Alumina Fine Particles (Zeolist Co., Ltd .: ZSM-5 [model number CVB3024E], SiO ₂ / Al ₂ O ₃ (mol / mol) = 30, average particle diameter 500 nm) was diluted with pure water and sulfuric acid so that the SiO ₂ .Al ₂ O ₃ concentration was 20 mass% and sulfate ions were 15,000 ppm.

  2 g of polyvinyl pyrrolidone (average molecular weight 1,000) is added to 100 g of this dispersion, then 10 g of amphoteric ion exchange resin (Mitsubishi Chemical: SMNUPB) is added and stirred at 50 ° C. for 3 hours, and then the ion exchange resin is separated. did. The pH at that time was 4.2. Thereafter, the resultant was concentrated with a rotary evaporator to obtain a resin-coated metal oxide particle (B-8) dispersion having a solid content of 20% by mass.

Preparation of coating liquid for forming ink-receiving layer (C-8) 52.5 g of the resin-coated metal oxide particle (B-8) dispersion obtained above was diluted with pure water to a concentration of 10% by mass as a matrix-forming component. 45 g of polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Co., Ltd .: Gohsenol GH-17R), 1 g of aluminum acetate and 1.5 g of pure water were sufficiently mixed to prepare a coating liquid (C-8) for forming an ink receiving layer. The stability of the coating solution was evaluated, and the results are shown in the table.

Preparation of recording sheet with ink receiving layer (D-8) Recording sheet with ink receiving layer (D-8) was prepared in the same manner as in Example 1 except that the coating liquid (C-8) for forming an ink receiving layer was used. ) Was prepared. The thickness of the receiving layer at this time was 20 μm.
The total light transmittance, haze, adhesion, scratch resistance and ink absorptivity of the obtained recording sheet with an ink receiving layer (D-8) were measured, and the results are shown in Table 1.

[Example 9]
Preparation of Resin Coated Metal Oxide Particles (B-10) Dispersion Silica / Alumina Fine Particles Silica / Alumina Fine Particles (Zeolist Co., Ltd .: ZSM-5 [model number CVB3024E], SiO ₂ / Al ₂ O ₃ (mol / mol) = 30, average particle diameter 500 nm) was diluted with pure water and sulfuric acid so that the SiO ₂ .Al ₂ O ₃ concentration was 20 mass% and sulfate ions were 15,000 ppm.

  To 100 g of this dispersion, 2 g of polyvinyl alcohol (manufactured by Kanto Chemical Co., Ltd .: average molecular weight 10,000) is added, and then 10 g of amphoteric ion exchange resin (manufactured by Mitsubishi Chemical Co., Ltd .: SMNUPB) is added, and the mixture is stirred at 50 ° C. for 3 hours. The exchange resin was separated. The pH at that time was 4.2. Thereafter, the resultant was concentrated by a rotary evaporator to obtain a resin-coated metal oxide particle (B-9) dispersion having a solid content of 20% by mass.

Preparation of coating liquid for forming ink-receiving layer (C-9) 52.5 g of the resin-coated metal oxide particle (B-9) dispersion obtained above was diluted with pure water to a concentration of 10% by mass as a matrix-forming component. 45 g of polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Co., Ltd .: Gohsenol GH-17R), 1 g of aluminum acetate and 1.5 g of pure water were sufficiently mixed to prepare a coating liquid (C-9) for forming an ink receiving layer. The stability of the coating solution was evaluated, and the results are shown in the table.

The ink-receiving layer film substrate with (D-9) of Preparation ink receiving layer coating solution (C-9) Example 1 and the same ink-receiving layer with the recording sheet by the method except for using (D-9 ) Was prepared. The thickness of the receiving layer at this time was 30 μm.
The total light transmittance, haze, adhesion, scratch resistance, and ink absorptivity of the obtained recording sheet with an ink receiving layer (D-9) were measured, and the results are shown in Table 1.

[Example 10]
Preparation of Resin Coated Metal Oxide Particle (B-10) Dispersion Titanium sulfate was dissolved in pure water to obtain an aqueous solution having a concentration of 0.4% by mass as TiO ₂ . While stirring this aqueous solution, ammonia water having a concentration of 15% by mass was gradually added to obtain a white slurry having a pH of 8.5. The slurry was filtered and then washed to obtain a hydrous titanic acid gel cake having a solid content concentration of 9% by mass.

After adding 6.06 kg of hydrogen peroxide having a concentration of 33% by mass and 13.4 kg of pure water to 5.55 kg of the cake, the cake was heated at 80 ° C. for 5 hours, and 25 kg of a solution having a concentration of 2.0% by mass as TiO _2. Got. This aqueous titanic acid solution was yellowish brown and transparent and had a pH of 8.1.

  Next, 130 g of silica sol having a particle size of 7 μm and a concentration of 15% by mass, 9 kg of the titanic acid aqueous solution and 10.8 kg of pure water were mixed, and then heated at 95 ° C. for 624 hours. The solution was initially a tan solution, but became a milky white transparent colloidal solution after 624 hours.

When the colloidal liquid thus obtained was concentrated by a vacuum evaporation method, titanium oxide particles having physical properties shown in Table 1 were obtained. 20 wt% solids concentration as TiO _2, SO ₄ ^2-ions include 3,000ppm against TiO ₂ solids, pH 8.5 titanium oxide particles (A-1) dispersion liquid was obtained .

  Thereafter, 2 g of polyvinylpyrrolidone (Tokyo Kasei Co., Ltd .: K-15, average molecular weight 10,000) was added to 100 g of the resulting titanium oxide particle (A-1) dispersion, and an amphoteric ion exchange resin (Mitsubishi Chemical Co., Ltd .: After adding 10 g of SMNUPB) and stirring at 50 ° C. for 3 hours, the ion exchange resin was separated. The pH at that time was 4.5. Thereafter, the resultant was concentrated using an ultra-thin film to obtain a resin-coated metal oxide particle (B-10) dispersion having a solid content of 20% by mass.

Preparation of coating liquid for forming ink-receiving layer (C-10) 60 g of resin-coated metal oxide particle (B-10) dispersion obtained above, polyvinyl alcohol diluted with pure water to a concentration of 10% by mass as a matrix-forming component (Nippon Synthetic Chemical Co., Ltd .: Gohsenol GH-17R) 30 g, aluminum acetate 1 g, and 2-propanol 9 g were sufficiently mixed to prepare an ink-receiving layer-forming coating solution (C-10). The stability of the coating solution was evaluated, and the results are shown in the table.

Preparation of recording sheet with ink receiving layer (D-10) Recording sheet with ink receiving layer (D-10) was prepared in the same manner as in Example 1 except that the coating liquid (C-10) for forming an ink receiving layer was used. ) Was prepared. The film thickness of the ink receiving layer at this time was 30 μm.
The recording sheet with an ink-receiving layer (D-10) was measured for total light transmittance, haze, adhesion, scratch resistance, and ink absorbability. The results are shown in Table 1.

[Example 11]
Preparation of resin-coated metal oxide particles (B-11) Alumina hydrate (manufactured by JGC Catalysts & Chemicals Co., Ltd .: AS-5, solid content concentration 20% by mass, average particle size 20 nm, acetic acid concentration 33,000 ppm, water dispersion 2 g of polyvinylpyrrolidone (average molecular weight 300) was added to 100 g of the medium, 10 g of amphoteric ion exchange resin (Mitsubishi Chemical: SMNUPB) was added and stirred at 50 ° C. for 3 hours, and then the ion exchange resin was separated. The pH at that time was 4.2. Thereafter, the resultant was concentrated using an ultra-fine membrane to obtain a resin-coated metal oxide particle (B-11) dispersion having a solid concentration of 20% by mass.

Preparation of coating liquid for forming ink receiving layer (C-11) 60 g of the resin-coated metal oxide particle (B-11) dispersion obtained above, polyvinyl alcohol diluted with pure water to a concentration of 10% by mass as a matrix-forming component (Nippon Synthetic Chemical Co., Ltd .: Gohsenol GH-17R) 30 g, aluminum acetate 1 g, and 2-propanol 9 g were sufficiently mixed to prepare an ink-receiving layer-forming coating solution (C-11). The stability of the coating solution was evaluated, and the results are shown in Table 1.

Preparation of recording sheet with ink receiving layer (D-11) Recording sheet with ink receiving layer (D-11) was prepared in the same manner as in Example 1 except that the coating liquid (C-11) for forming an ink receiving layer was used. ) Was prepared. The thickness of the receiving layer at this time was 30 μm.
The recording sheet with an ink-receiving layer (D-11) was measured for total light transmittance, haze, adhesion, scratch resistance, and ink absorbability. The results are shown in Table 1.

[Example 12]
Preparation of resin-coated metal oxide particles (B-12) Alumina hydrate (manufactured by JGC Catalysts & Chemicals Co., Ltd .: AS-5, solid content concentration 20% by mass, average particle size 20 nm, acetic acid concentration 33,000 ppm, water dispersion 2 g of polyvinylpyrrolidone (manufactured by Kanto Chemical Co., Inc .: K-85-95 average molecular weight 1,300,000) is added to 100 g, and 10 g of amphoteric ion exchange resin (manufactured by Mitsubishi Chemical: SMNUPB) is added at 50 ° C. for 3 hours. After stirring, the ion exchange resin was separated. The pH at that time was 4.2. Thereafter, the resultant was concentrated using an ultra-fine membrane to obtain a resin-coated metal oxide particle (B-12) dispersion having a solid concentration of 20% by mass.

Preparation of coating liquid for forming ink-receiving layer (C-12) 60 g of resin-coated metal oxide particle (B-12) dispersion obtained above, polyvinyl alcohol diluted with pure water to a concentration of 10% by mass as a matrix-forming component (Nippon Synthetic Chemical Co., Ltd .: Gohsenol GH-17R) 30 g, aluminum acetate 1 g, and 2-propanol 9 g were sufficiently mixed to prepare an ink-receiving layer-forming coating solution (C-12). The stability of the coating solution was evaluated, and the results are shown in the table.

Preparation of recording sheet with ink receiving layer (D-12) Recording sheet with ink receiving layer (D-12) was prepared in the same manner as in Example 1 except that the coating liquid (C-12) for forming an ink receiving layer was used. ) Was prepared. The thickness of the receiving layer at this time was 30 μm.
The total light transmittance, haze, adhesion, scratch resistance, and ink absorptivity of the obtained recording sheet with an ink receiving layer (D-12) were measured, and the results are shown in Table 1.

[Comparative Example 1]
Preparation of ink receiving layer forming coating solution (RC-1) Alumina hydrate (manufactured by JGC Catalysts & Chemicals Co., Ltd .: AS-5, solid content concentration 20% by mass, average particle size 20 nm, acetic acid concentration 33,000 ppm, water Dispersion medium) 60 g, 30 g of polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Co., Ltd .: Gohsenol GH-17R) diluted with pure water to a concentration of 10% by mass as a matrix forming component, 1 g of aluminum acetate, and 9 g of 2-propanol were mixed thoroughly. Thus, an ink receiving layer forming coating solution (RC-1) was prepared. The stability of the coating solution was evaluated, and the results are shown in the table.

Preparation of recording sheet with ink receiving layer (RD-1) Recording sheet with ink receiving layer (RD-1) was prepared in the same manner as in Example 1 except that the coating liquid (RC-1) for forming an ink receiving layer was used. ) Was prepared. The thickness of the receiving layer at this time was 30 μm.
The total light transmittance, haze, adhesion, scratch resistance, and ink absorptivity of the obtained recording sheet with an ink receiving layer (RD-1) were measured, and the results are shown in Table 1.

[Comparative Example 2]
Preparation of ink receiving layer forming coating solution (RC-2) Silica fine particles (manufactured by JGC Catalysts & Chemicals Co., Ltd .: silica microbead P-500, average particle size 1,500 nm) 60 g, concentration of 10% by mass as a matrix forming component 30 g of polyvinyl alcohol diluted with pure water (manufactured by Nippon Synthetic Chemical Co., Ltd .: Gohsenol GH-17R), 1 g of aluminum acetate, and 9 g of 2-propanol are mixed well to form an ink receiving layer forming coating solution (RC-2) Was prepared. The stability of the coating solution was evaluated, and the results are shown in the table.

Preparation of recording sheet with ink receiving layer (RD-2) Recording sheet with ink receiving layer (RD-2) was prepared in the same manner as in Example 1 except that the coating liquid (RC-2) for forming the ink receiving layer was used. ) Was prepared. The thickness of the receiving layer at this time was 30 μm.
The total light transmittance, haze, adhesion, scratch resistance, and ink absorptivity of the obtained recording sheet with an ink receiving layer (RD-2) were measured, and the results are shown in Table 1.

[Comparative Example 3]
Preparation of coating liquid for forming ink receiving layer (RC-3) Silica / alumina fine particles (manufactured by JGC Catalysts & Chemicals Co., Ltd .: ZSM-5, alumina content 20 mass%, average particle diameter 500 nm) 60 g, matrix 30 g of polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Co., Ltd .: Gohsenol GH-17R), 1 g of aluminum acetate, and 9 g of 2-propanol were mixed well as a forming component to form an ink receiving layer. A coating solution (RC-3) was prepared. The stability of the coating solution was evaluated, and the results are shown in the table.

Preparation of recording sheet with ink receiving layer (RD-3) Recording sheet with ink receiving layer (RD-3) was prepared in the same manner as in Example 1 except that the coating liquid (RC-3) for forming the ink receiving layer was used. ) Was prepared. The thickness of the receiving layer at this time was 30 μm.
The total light transmittance, haze, adhesion, scratch resistance, and ink absorptivity of the obtained recording sheet with an ink receiving layer (RD-3) were measured, and the results are shown in Table 1.

[Comparative Example 4]
Preparation of ink receiving layer forming coating solution (RC-4) 60 g of titanium oxide particle (A-1) dispersion having a solid content of 20% by mass as TiO ₂ prepared in the same manner as in Example 10 as a matrix forming component 30 g of polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Co., Ltd .: Gohsenol GH-17R) diluted with pure water to a concentration of 10% by mass, 1 g of aluminum acetate and 9 g of 2-propanol are mixed thoroughly to form a coating solution for forming an ink receiving layer. (RC-4) was prepared. The stability of the coating solution was evaluated, and the results are shown in the table.

Preparation of recording sheet with ink receiving layer (RD-4) Recording sheet with ink receiving layer (RD-4) was prepared in the same manner as in Example 1 except that the coating liquid (RC-4) for forming the ink receiving layer was used. ) Was prepared. The thickness of the receiving layer at this time was 30 μm.
The recording sheet with an ink-receiving layer (RD-4) was measured for total light transmittance, haze, adhesion, scratch resistance, and ink absorbability. The results are shown in Table 1.

[Reference Example 5]
Preparation of resin-coated metal oxide particles (RB-5) Alumina hydrate particles (manufactured by JGC Catalysts & Chemicals Co., Ltd .: AS-5, solid content concentration 20% by mass, average particle size 20 nm, acetic acid concentration 33,000 ppm, water 2 g of polyvinylpyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd .: K-15, average molecular weight 10,000) was added to 100 g of the dispersion medium and stirred at 50 ° C. for 3 hours. The pH at that time was 44.5. Thereafter, it was diluted with pure water to obtain a resin-coated metal oxide particle (RB-5) dispersion having a solid content concentration of 20% by mass.

Preparation of recording sheet with ink receiving layer (RD-5) In the same manner as in Example 1, 60 g of resin-coated metal oxide particle (RB-5) dispersion, diluted with pure water to a concentration of 10% by mass as a matrix-forming component 30 g of the prepared polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Co., Ltd .: Gohsenol GH-17R), 1 g of aluminum acetate and 9 g of 2-propanol were mixed thoroughly to prepare a coating solution for forming an ink receiving layer (RC-5). Similarly, a recording sheet (RD-5) with an ink receiving layer was prepared. The thickness of the receiving layer at this time was 30 μm.
The total light transmittance, haze, adhesion, scratch resistance, and ink absorbability of the obtained recording sheet with an ink receiving layer (RD-5) were measured, and the results are shown in Table 1.

[Comparative Example 6]
Preparation of resin-coated metal oxide particle (RB-6) dispersion Silica fine particles (manufactured by JGC Catalysts & Chemicals Co., Ltd .: silica microbead P-500, average particle size 1500 nm) and polyacrylic acid (manufactured by Aldrich: average molecular weight) (5000, solid content 63 wt%) 79.5 g was added and mixed with a ball mill for 1 hour to coat the resin. Then, it was dried at 80 ° C. and then dispersed in pure water to obtain a resin-coated metal oxide particle (RB-6) dispersion having a solid content concentration of 20% by weight.

Preparation of coating solution (RC-6) for forming an ink-receiving layer 52,5 g of the resin-coated metal oxide particle (RB-6) dispersion obtained above, diluted with pure water to a concentration of 10% by weight as a matrix-forming component The ink-receiving layer forming coating solution (RC-6) was prepared by thoroughly mixing 45 g of polyvinyl alcohol (Nippon Synthetic Chemical Co., Ltd .: Gohsenol GH-17R), 1 g of aluminum acetate, and 1.5 g of pure water. . The stability of the coating solution was evaluated, and the results are shown in Table 1.

Preparation of recording sheet with ink receiving layer (RD-6) Recording sheet with ink receiving layer (RD-6) was prepared in the same manner as in Example 1 except that the coating liquid (RC-6) for forming the ink receiving layer was used. ) Was prepared. At this time, the thickness of the receiving layer was 40 μm.

  The recording sheet with an ink-receiving layer (RD-6) was evaluated for total light transmittance, haze, adhesion, scratch resistance, and ink absorbability. The results are shown in Table 1.

Claims (11)

  A coating solution for forming an ink receiving layer, comprising resin-coated metal oxide particles and a matrix-forming component.   The coating for forming an ink receiving layer according to claim 1, wherein the coating resin of the resin-coated metal oxide particles is at least one resin selected from polyacrylic acid, polyvinyl alcohol, polyvinyl pyrrolidone, and celluloses. liquid.   The coating amount of the resin in the resin-coated metal oxide particles is in the range of 0.5 to 50% by mass as solid content (coating resin weight / coating particle weight). Coating liquid for forming an ink receiving layer. The metal oxide particles are one or more selected from the group consisting of MgO, TiO ₂ , SiO ₂ , ZrO ₂ , Al ₂ O ₃ , Sb ₂ O ₅ , ZnO, and composite oxides thereof. The coating liquid for forming an ink receiving layer according to claim 1. When the resin-coated metal oxide particles are single particles and / or aggregate particles of two or more single particles, the average primary particle diameter (D ₁ ) is in the range of 10 to 5000 nm. The coating liquid for forming an ink receiving layer according to claim 1, wherein the diameter (secondary particle diameter (D ₂ )) is in the range of 20 to 10,000 nm. The ratio (D ₂ ) / (D ₁ ) between the average secondary particle diameter (D ₂ ) and the average primary particle diameter (D ₁ ) is in the range of 1-20. The coating liquid for forming an ink receiving layer according to any one of the above.   7. The ink receiving layer forming apparatus according to claim 1, wherein the matrix forming component is at least one resin selected from polyacrylic resins, polyvinyl alcohol resins, and polyvinylpyrrolidone resins. Coating liquid.   The coating liquid for forming an ink receiving layer according to any one of claims 1 to 7, wherein the matrix forming component is resin fine particles having an average particle diameter in the range of 5 nm to 20 µm.   9. The resin fine particle according to claim 1, wherein the resin fine particle is at least one selected from acrylic cross-linked copolymer fine particles, urethane cross-linked copolymer fine particles, and acrylic-urethane cross-linked copolymer fine particles. A coating liquid for forming an ink-receiving layer according to claim 1. After the resin fine particles have added a coating resin to the (a) metal oxide particle dispersion,
The ion exchange resin (b) is obtained by adjusting the anion concentration in the dispersion so as to be 1 to 10,000 ppm per unit weight of the metal oxide particles. The coating solution for forming an ink receiving layer according to any one of the above.   It consists of a base material sheet and an ink receiving layer formed on the base material sheet, and the ink receiving layer is formed using the ink receiving layer forming coating liquid according to any one of claims 1 to 10. A recording sheet with an ink-receiving layer.