JP2007007993A - Inkjet recording sheet and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording sheet, in which cracking in an ink accepting layer is prevented from developing and which is excellent in long term storage stability, and its manufacturing method. <P>SOLUTION: In this sheet, the ink accepting layer including fine inorganic particles, a cationic polymer and a binder is formed on a support. In addition, this sheet includes a hindered amine base light stabilizer as a specified polymer (B). Further, the cationic polymer includes a polymer (A) having a specified constituent unit (a1) or a specified constituent unit (a2). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet recording sheet in which an ink receiving layer containing inorganic fine particles, a cationic polymer, and a binder is formed on a support, and a method for producing the same.

  The ink jet recording method that forms an image by ejecting liquid ink from a fine nozzle onto a recording body has low noise during recording, easy colorization, high-speed recording, and other printing It is widely used in terminal printers, facsimiles, plotters, form printing, and the like because it is less expensive than the apparatus. In recent years, due to the rapid spread of printers, high definition and high speed, and the advent of digital cameras, advanced characteristics have also been demanded on the recording medium side. That is, there is a strong demand for the realization of a recording medium having both image quality and storage stability comparable to silver salt photographs excellent in ink absorption, recording density, water resistance and storage stability.

  In order to improve the ink absorptivity, recording density, image quality, etc. of the ink jet recording sheet, for example, a method of providing inorganic fine particles such as amorphous silica on a support together with a binder as an ink receiving layer has been proposed. In order to improve the gloss and image quality of the ink jet recording sheet, a method using synthetic silica fine particles in the ink receiving layer has been proposed. Furthermore, in order to improve the recording density and the water resistance of the image, a method of incorporating a cationic polymer or a basic latex in the ink receiving layer has been proposed.

On the other hand, a method of adding at least one of metal oxides such as phosphotungstic acid, phosphomolybdic acid, and chromic chloride, metal chloride, and tannic acid, hindered phenols, in order to improve image storability A method of adding an antioxidant such as a method, a method of adding a hindered amine, a method of adding a UV absorber such as benzophenone, benzotriazole or phenylsalicylic acid, a method of adding a thiourea compound, 2-mercaptobenzo Method of adding a specific mercapto compound such as thiazole, 2-mercaptobenzimidazole, method of adding dithiocarbamate, thiuram salt, thiocyanate or thiocyanate, method of adding basic polyaluminum hydroxide, acidification Method for adding zirconium-based active inorganic polymer Of a method of adding various additives it has been proposed (e.g., see Patent Document 1 to 11).
JP-A-57-87987 JP-A-57-74192 JP-A 61-146591 JP-A-57-74193 JP-A-57-87988 Japanese Patent Laid-Open No. 63-222885 JP 61-163886 A JP-A 61-177279 JP 7-314882 A JP-A-60-257286 JP-A-6-32046

However, a full-color inkjet recording image formed using an inkjet recording sheet to which the above additives are added has a high printing density and excellent color developability. However, the long-term storage stability of the image (specifically, light resistance) Properties, water resistance and heat and humidity resistance) were insufficient.
Further, any of the above-described inkjet recording sheets is liable to crack on the surface of the ink receiving layer, which causes problems such as deterioration of the glossiness of the sheet and deterioration of the image quality of the formed image.
An object of the present invention is to provide an ink jet recording sheet which is prevented from cracking of an ink receiving layer and has excellent long-term storage stability, and a method for producing the same.

  The present inventors use inorganic fine particles having an average primary particle size of 30 nm or less and a cationic polymer having a specific structural unit as the inorganic fine particles to be contained in the ink receiving layer, and further, a specific hindered amine light stabilizer. It has been found that these problems can be solved by using, and the present invention has been completed.

The present invention includes the following embodiments.
[1] In an ink jet recording sheet comprising an ink receiving layer containing inorganic fine particles, a cationic polymer, and a binder on a support, and containing a hindered amine light stabilizer,
The polymer in which the cationic polymer has at least one structural unit (a1) represented by the following general formula (1) or at least one structural unit (a2) represented by the following general formula (2) ( A), including
The hindered amine light stabilizer is at least one structural unit (b1) represented by the following general formula (3), and at least one structural formula (4) and / or general formula (5). An ink jet recording sheet which is a polymer (B) containing the structural unit (b2).
[2] The inkjet recording sheet according to [1], wherein the polymer (A) contained in the cationic polymer further contains at least one structural unit (a3) represented by the general formula (6).
[3] The ink jet recording sheet according to [1], wherein the polymer (A) contained in the cationic polymer further contains at least one structural unit (a4) represented by the general formula (7).
[4] The inkjet recording sheet according to any one of [1] to [3], wherein the structural unit (b2) is a structural unit represented by the following general formula (8).
[5] The inkjet recording sheet according to any one of [1] to [4], wherein the average primary particle diameter of the inorganic fine particles is 30 nm or less.
[6] A method for producing an ink jet recording sheet, wherein an ink receiving layer is formed by applying a coating liquid for forming an ink receiving layer containing inorganic fine particles, a cationic polymer, a binder, and a hindered amine light stabilizer on a support. Because
The polymer in which the cationic polymer has at least one structural unit (a1) represented by the following general formula (1) or at least one structural unit (a2) represented by the following general formula (2) ( A), including
The hindered amine light stabilizer is at least one structural unit (b1) represented by the following general formula (3), and at least one structural formula (4) and / or general formula (5). A method for producing an inkjet recording sheet, which is a polymer (B) containing the structural unit (b2).
[7] A first ink-receiving layer-forming coating liquid containing inorganic fine particles and a binder, a light stabilizer-containing liquid containing a hindered amine light stabilizer, and inorganic fine particles and a binder on the support. A method for producing an ink-jet recording sheet, wherein the ink-receiving layer is formed by sequentially applying the ink-receiving layer-forming coating liquid of No. 2;
The light stabilizer-containing liquid or the second ink-receiving layer-forming coating liquid further contains a cationic polymer, and the cationic polymer contains at least one structural unit (a1) represented by the following general formula (1): Or a polymer (A) having at least one structural unit (a2) represented by the following general formula (2):
The hindered amine light stabilizer is at least one structural unit (b1) represented by the following general formula (3), and at least one structural formula (4) and / or general formula (5). A method for producing an inkjet recording sheet, which is a polymer (B) containing the structural unit (b2).
[8] The method for producing an inkjet recording sheet according to [7], wherein the light stabilizer-containing liquid further contains a crosslinking agent.
[9] The inkjet recording according to any one of [6] to [8], wherein the polymer (A) contained in the cationic polymer further contains at least one structural unit (a3) represented by the general formula (6). Sheet manufacturing method.
[10] The inkjet recording according to any one of [6] to [8], wherein the polymer (A) contained in the cationic polymer further contains at least one structural unit (a4) represented by the general formula (7). Sheet manufacturing method.

[Wherein, X represents an acid residue. ]

[Wherein Y represents an acid residue. ]

[Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁸ , R ⁹ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ^{5 to} R ⁷ each independently represent carbon. The alkyl group of number 1-8 is represented, Z represents an acid residue, n represents the integer of 1-6. R ¹⁰ and R ¹¹ each independently represents an oxygen atom or N—R ¹⁴ . Here, R ¹⁴ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. R ¹² and R ¹³ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. ]

[Wherein, R ¹⁵ and R ¹⁶ each independently represents a hydrogen atom or a methyl group. R ^{17 to} R ¹⁹ each independently represents an alkyl group having 1 to 3 carbon atoms. W represents an acid residue. ]

The ink jet recording sheet of the present invention is greatly improved in cracking of the ink receiving layer, and is excellent in long-term storage (light resistance, water resistance, heat resistance and humidity resistance).
According to the method for producing an ink jet recording sheet of the present invention, it is possible to produce an ink jet recording sheet which is greatly improved in cracking of the ink receiving layer and excellent in long-term storage (light resistance, water resistance, heat and humidity resistance).

Hereinafter, the present invention will be described in more detail.
The ink jet recording sheet of the present invention is obtained by forming an ink receiving layer containing inorganic fine particles, a cationic polymer, and a binder on a support.

≪Support body≫
As the support, known ink jet recording paper can be used as appropriate.
Specific examples of the support include, for example, paper (acid paper, neutral paper, etc.), baryta paper, synthetic paper, plastic film, a support coated with plastic on one or both sides of paper (RC paper), paper The thing etc. which bonded the nonwoven fabric or the plastic film on the single side | surface or both surfaces through the adhesive agent are mentioned.
Examples of the plastic film include polyolefin resins such as polyester and polypropylene, films such as nylon, and synthetic paper.

In order to obtain a clear image at a higher density, it is preferable to use a water-resistant support that does not easily penetrate the ink liquid among the above supports.
As the water-resistant support, a support in which both sides of paper are coated with a polyolefin resin is particularly preferable because the recorded image is close to photographic image quality and a high-quality image can be obtained at low cost.

  As will be described later, when the ink receiving layer is cast or when a cast gloss layer is formed on the ink receiving layer, paper (acidic paper, neutral paper, etc.), coat Absorbent supports such as paper and baryta paper can also be preferably used. In the case of an absorbent support, the water in the ink-receiving layer-forming coating liquid escapes through the support during the casting process, which facilitates the casting process. In addition, ink absorbability and ink drying properties are good, and high-speed printability is excellent.

  Although there is no restriction | limiting in particular as thickness of a support body, 100-400 micrometers is preferable.

≪Ink receiving layer≫
<Inorganic fine particles>
The average primary particle diameter of the inorganic fine particles contained in the ink receiving layer is preferably 30 nm or less, and more preferably 3 to 15 nm. When the average primary particle diameter of the inorganic fine particles is 30 nm or less, an ink receiving layer having high transparency and excellent print density, gloss, ink absorbability, and the like can be obtained.
The average particle diameter referred to in the present invention is the particle diameter observed with an electron microscope (SEM and TEM) (taken an electron micrograph of 10,000 to 400,000 times, and measured the average particle diameter of particles in a 5 cm square. (It is described in "Particle Handbook", Asakura Shoten, p52, 1991, etc.).

  When the inorganic fine particles are aggregated particles (secondary particles) in which primary particles are aggregated, the average secondary particle diameter is not particularly limited, but is preferably 0.05 to 1.0 μm, More preferably, it is 0.5 μm.

The specific surface area of the inorganic fine particles by BET method is preferably 100 m ² / g or more, and preferably about 1000 m ² / g or less. More preferably, it is 200-400 m < ² > / g.
The BET method referred to in the present invention is one of powder surface area measurement methods by vapor phase adsorption, and is a method for determining the total surface area, that is, the specific surface area of a 1 g sample from an adsorption isotherm.

  Examples of inorganic fine particles include zeolite, light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium oxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, and silicic acid. Examples thereof include aluminum, diatomaceous earth, calcium silicate, magnesium silicate, silica, aluminum hydroxide, alumina, alumina hydrate, aluminosilicate, boehmite, pseudoboehmite and the like. Among these, silica, alumina, alumina hydrate and aluminosilicate are particularly preferable from the viewpoint of ink absorbability, and silica is particularly preferable.

Silica is roughly classified into natural silica obtained by pulverizing natural silica such as quartz and synthetic silica produced by synthesis, and synthetic silica is broadly classified into vapor-phase method silica and wet method silica. . In the present invention, the wet method fine silica described later is preferably used among the vapor phase method silica and the wet method silica because high ink absorbability, transparency, and gloss can be obtained.
Vapor phase silica is also called a dry method as opposed to a wet method, and is made by a flame hydrolysis method. Specifically, it is made by burning silicon tetrachloride with hydrogen and oxygen. In place of silicon tetrachloride, silanes such as methyltrichlorosilane and trichlorosilane may be used alone or mixed with silicon tetrachloride. Vapor phase method silica is commercially available as a powder having a very low bulk density.
When the aqueous dispersion of vapor phase silica is dried, it becomes porous silica gel, and the pore volume of the gel by the BET method is generally 1.2 to 1.6 ml / g. This pore volume is convenient for absorbing ink. However, cracks tend to occur during drying, and it is not easy to produce an ink receiving layer free of cracks.

As the wet method silica, silica by a precipitation method and silica by a gel method are known.
For example, as disclosed in JP-A-55-116613, the precipitated silica is produced by adding a mineral acid stepwise to an alkali silicate aqueous solution and filtering the precipitated silica.
The gel method silica is obtained by mixing a mineral acid with an alkali silicate solution, gelling, washing, and pulverizing.
Precipitated silica and gel silica combine primary particles of silica to form secondary particles, and since there are many voids between primary particles and secondary particles, the ink absorption amount is large, Since the property of scattering light is small, a high printing density can be obtained.

  Further, as a wet process silica by a slightly special production method, for example, active silicic acid is condensed as described in US Pat. No. 2,574,902, JP-A No. 2001-354408, JP-A No. 2002-145609. There is fine silica (hereinafter, referred to as wet method fine silica) produced. Here, the active silicic acid refers to an aqueous silicic acid solution having a pH of 4 or less obtained by ion-exchange treatment of an aqueous alkali metal silicate solution with a hydrogen cation exchange resin, for example.

The wet method fine silica described in US Pat. No. 2,574,902 prepares an aqueous solution of active silicate by treating a diluted aqueous solution of sodium silicate with a cation exchange resin to remove sodium ions. Part of the solution is stabilized by adding alkali to polymerize to form a liquid in which silica seed particles are dispersed (seed liquid), and the remaining portion of the active silicic acid aqueous solution (feed liquid) is maintained while maintaining alkaline conditions. It is produced by gradually adding silica to polymerize silicic acid and growing colloidal silica particles.
This fine silica has a feature that it has a diameter of 3 nm to several hundreds nm, does not undergo secondary aggregation, and has a very narrow particle size distribution. Usually, it is called colloidal silica, and a product of 7 to 100 nm is commercially available as an aqueous dispersion, and when used in an ink receiving layer, a receiving layer having extremely high gloss and high transparency can be obtained.

On the other hand, the wet method fine silica described in JP-A-2001-354408 is “silica fine particles having a specific surface area of 300 to 1000 m ² / g and a pore volume of 0.4 to 2.0 ml / g according to the BET method. After adding a colloidally dispersed liquid as a seed liquid and adding alkali to the seed liquid, a feed liquid consisting of at least one selected from an aqueous solution of active silicic acid and alkoxysilane is added to the seed liquid little by little. Silica having a specific surface area by BET method of 100 to 400 m ² / g, an average secondary particle diameter of 20 to 300 nm, and a pore volume of 0.5 to 2.0 ml / g, characterized by growing silica fine particles method for producing a silica fine particle dispersion in which fine particles are dispersed in a colloidal form. ", or" the specific surface area by BET method at 300~1000m ² / g, a pore volume of A liquid in which silica fine particles of 4 to 2.0 ml / g are dispersed in a colloidal form is used as a seed liquid, and a mixture of at least one feed liquid selected from active silicic acid aqueous solution and alkoxysilane with respect to the seed liquid and an alkali. Is added in small portions, or the feed liquid and alkali are added in small portions at the same time to grow silica fine particles. The BET method has a specific surface area of 100 to 400 m ² / g and an average secondary particle size of This is a silica fine particle obtained by “a method for producing a silica fine particle dispersion in which silica fine particles having a pore volume of 20 to 300 nm and a pore volume of 0.5 to 2.0 ml / g are colloidally dispersed”.

  Further, the wet method fine silica described in JP-A No. 2002-145609 is “a suspension containing an aggregate composed of silica fine particles by heating an aqueous solution containing at least one selected from activated silicic acid and alkoxysilane. Next, at least one selected from an aqueous solution containing active silicic acid in the presence of alkali and alkoxysilane was added little by little to the suspension to grow silica fine particles in the suspension. Thereafter, the suspension is wet-pulverized, and the silica fine particles are obtained by a method for producing a silica fine particle dispersion.

  The wet method fine silica disclosed in Japanese Patent Application Laid-Open Nos. 2001-354408 and 2002-145609 is a silica having both the advantages of precipitation method silica and gel method silica and the advantages of colloidal silica. This silica is a secondary particle in which primary particles of silica (for example, the colloidal silica described above) are bonded, and it is easy to adjust the secondary particle diameter to be equal to or less than the wavelength of light. It is most preferably used in the present invention because an ink-receiving layer having excellent resistance can be easily produced. Hereinafter, these wet process fine silicas are referred to as secondary fine silicas.

Among these, in particular, the secondary fine silica produced by the condensation method disclosed in JP-A No. 2001-354408 is directly related to the average secondary particle diameter (20 to 300 nm) and fine particle size without using mechanical means. Since secondary fine silica having a pore volume (0.5 to 2.0 ml / g) can be produced and the particle size distribution is narrow, the resulting ink-receiving layer has good transparency and gloss, and is preferably used in the present invention. Can do.
In the condensation method disclosed in JP-A-2001-354408, as the active silicic acid, for example, an aqueous silicic acid solution having a pH of 4 or less obtained by ion-exchange treatment of an aqueous alkali metal silicate solution with a hydrogen cation exchange resin. (Activated silicic acid aqueous solution) is preferably used.
The active silicic acid aqueous solution is preferably 1 to 6% by mass as SiO ₂ concentration, more preferably 2 to 5% by mass, and preferably pH 2 to 4.
The alkali metal silicate may be a commercially available industrial product, and more preferably a sodium water glass having a SiO ₂ / M ₂ O (where M represents an alkali metal atom) molar ratio of about 2 to 4. It is preferable to use it.
As a method for condensing active silicic acid, the above active silicic acid aqueous solution is dropped into hot water, or the active silicic acid aqueous solution is heated to produce seed particles, before the dispersion is precipitated or gelled. the seed particles are stabilized by adding an alkali, then, while maintaining the stable state, in terms of SiO ₂ the active silicic acid solution with respect to SiO ₂ 1 mole contained in the seed particles 0.001 The seed particles are preferably grown at a rate of mol / min to grow the primary particles of the seed particles.

The wet process fine silica preferably has a specific surface area of 100 to 400 m ² / g by the BET method and a pore volume of 0.5 to 2.0 ml / g. Fine silica in this range has a very good balance of cracks in the ink receiving layer, ink absorbency, and gloss.

  Moreover, it is also preferable to use silica-cationic compound aggregate fine particles as silica. Here, the silica-cationic compound aggregate fine particles are obtained by pulverizing silica-cationic compound aggregate particles obtained by mixing and aggregating amorphous silica and a cationic compound. The fine particles of the silica-cationic compound aggregate are substantially composed of secondary particles formed by aggregating primary particles.

  The amorphous silica constituting the silica-cationic compound aggregate fine particles preferably has an average primary particle diameter of 3 to 40 nm. If it is less than 3 nm, the gap between the primary particles becomes extremely small, and the ability to absorb the solvent and ink in the ink is remarkably lowered. On the other hand, if it exceeds 40 nm, the secondary particles become large and the transparency of the ink receiving layer may be lowered.

As the cationic compound used in the formation of the silica-cationic compound aggregate fine particles, various known cationic compounds generally used in ink jet recording paper can be used, for example, monoallylamine salts, vinylamine salts, Primary amine type cationic polymer having a primary amine salt such as N-vinylacrylamidine salt, dicyandiamide / formalin polycondensate, dicyandiamide / polyethyleneamine polycondensate as a structural unit, secondary amine such as diallylamine salt, ethyleneimine salt Secondary amine type cationic polymer having a salt as a structural unit, tertiary amine type cationic polymer having a tertiary amine salt as a structural unit such as diallylmethylamine salt, diallyldimethylammonium chloride, (meth) acryloyloxyethyltrimethyl Quaternary ammonium-type cationic polymers having a quaternary ammonium salt such as ammonium chloride, (meth) acrylamidopropyltrimethylammonium chloride, dimethylamine / epichlorohydrin polycondensate as a structural unit, basic polyaluminum chloride, basic polyfatty acid aluminum, etc. Examples thereof include aluminum compounds, zirconyl chloride, basic zirconyl chloride, and zirconyl compounds such as fatty acid zirconyl.
The addition amount of the cationic compound is preferably adjusted in the range of 1 to 30 parts by mass, more preferably 5 to 20 parts by mass with respect to 100 parts by mass of amorphous silica.

  As a method for pulverizing the silica-cationic compound aggregate particles when producing the silica-cationic compound aggregate fine particles, a breaking down method (a method of subdividing the bulk material) that gives a strong force by mechanical means is employed. It is done. Examples of the mechanical means include an ultrasonic wave, a high-speed rotating mill, a roller mill, a container driving medium mill, a medium stirring mill, a jet mill, a disintegrator, and a sand grinder.

  The average particle size of the silica-cationic compound aggregate fine particles is preferably 700 nm or less, more preferably 10 to 300 nm, and particularly preferably 20 to 200 nm. When the average particle diameter exceeds 700 nm, the transparency is remarkably lost, the printing density is remarkably lowered, and the gloss after printing may be lowered. On the other hand, if the average particle size is extremely small, there is a possibility that a sufficient ink absorption rate cannot be obtained.

  By using such silica-cationic compound aggregate fine particles, the transparency of the ink receiving layer, the ink absorbability, the ink coloring property, and the weather resistance can be improved, and the resulting inkjet recording sheet is used for OHP. It can also be used as a sheet or the like.

  The content of the inorganic fine particles in the ink receiving layer is preferably about 20 to 90% by mass and more preferably about 30 to 80% by mass with respect to the solid content of the ink receiving layer. If it is this range, there is no possibility that the coating strength of the ink receiving layer is lowered, the ink absorbability and the ink drying property are excellent, and the image quality becomes high.

<Cationic polymer>
The cationic polymer is a polymer having at least one structural unit (a1) represented by the following general formula (1) or at least one structural unit (a2) represented by the following general formula (2) (A ).
In general formula (1) and general formula (2), the acid represented by HX and HY may be either an inorganic acid or an organic acid. Examples of inorganic acids include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, pyrophosphoric acid, Examples of organic acids such as metaphosphoric acid include formic acid, acetic acid, propionic acid, methanesulfonic acid, and p-toluenesulfonic acid. These can be used alone or in combination of two or more. Among these acids, hydrochloric acid and sulfuric acid are particularly preferable because they are effective for image storability.

[Wherein, X represents an acid residue. ]

[Wherein Y represents an acid residue. ]

  The polymer (A) contained in the cationic polymer may further contain at least one structural unit (a3) represented by the general formula (6), or at least one structure represented by the general formula (7). The unit (a4) may be included.

  The mass average molecular weight of the cationic polymer is preferably 1,000 to 500,000, and more preferably 10,000 to 200,000. If the mass average molecular weight is within this range, the coating stability is good, high image quality is obtained, light resistance, heat and humidity resistance, etc., and ink absorbency are excellent, and more cracking is achieved. Can be prevented.

The content of the cationic polymer in the ink receiving layer is preferably 0.01 to 10 g / m ² , and more preferably 0.05 to 5 g / m ² . When the content of the cationic polymer is within this range, the image quality, image storage stability, and ink absorption are excellent.
Moreover, the cationic polymer in this invention may also contain various well-known cationic polymers other than a polymer (A) in the range which does not inhibit this invention.

<Binder>
Examples of the binder contained in the ink receiving layer include starch derivatives such as oxidized starch and etherified starch, cellulose derivatives such as carboxymethylcellulose and hydroxyethylcellulose, proteins such as casein, gelatin and soybean protein, and complete (partial) Ken. Polyvinyl alcohol, silicon-modified polyvinyl alcohol, polyvinyl alcohols such as acetoacetyl group-modified polyvinyl alcohol, cation-modified polyvinyl alcohol, salts of styrene-maleic anhydride copolymer, styrene-butadiene latex, acrylic latex, polyester polyurethane Aqueous adhesive such as latex, vinyl acetate latex, or polymethyl methacrylate, polyurethane, unsaturated polyester resin, vinyl chloride-vinyl acetate copolymer, Polyvinyl butyral, and organic solvent-soluble resins such as alkyd resin. These binders may be used alone or in combination.

  Among these binders, polyvinyl alcohols are preferable because they have high transparency, high water resistance, are nonionic, can be mixed with various materials, and have a relatively low swelling property near room temperature. Further, it can be prevented that the ink swells during the initial penetration of the ink and closes the gap.

  Furthermore, among polyvinyl alcohols, completely (partially) saponified polyvinyl alcohol, cation-modified polyvinyl alcohol or silicon-modified polyvinyl alcohol is particularly preferably used.

As the completely (partially) saponified polyvinyl alcohol, a partially saponified polyvinyl alcohol or a completely saponified polyvinyl alcohol having a saponification degree of 80% or more, particularly 95% or more is preferable. Moreover, as the average degree of polymerization, 200-5,000 are preferable and 500-5,000 are more preferable.
The reason why a portion having a saponification degree of 80% or more or a completely saponified polyvinyl alcohol is preferable is that it has excellent water resistance. The reason why the average degree of polymerization is preferably 200 to 5,000 is that when a polymer having a degree of polymerization in this range is used, the viscosity is excellent in water resistance and easy to handle.

  The cation-modified polyvinyl alcohol is preferably polyvinyl alcohol having a primary, secondary, or tertiary amino group or a quaternary ammonium base in the main chain or side chain of the polyvinyl alcohol.

  The binder is used in an amount of preferably 1 to 100 parts by mass, more preferably 5 to 50 parts by mass with respect to 100 parts by mass of the inorganic fine particles.

  When silica-cationic compound aggregate fine particles are used as the inorganic fine particles, polyvinyl alcohol having an average degree of polymerization of 2,000 or more is preferably used as the binder, more preferably from the viewpoint of dispersion suitability and coating stability. Polyvinyl alcohol having an average degree of polymerization of 2,000 to 5,000 is used. In order to obtain water resistance, it is preferable to use polyvinyl alcohol having a saponification degree of 95% or more as a binder.

  The solid content mass ratio between the binder and the silica-cationic compound aggregate fine particles is not particularly limited, but is preferably 10/1 to 10/10, and more preferably 10/1 to 10/5. When the amount of the binder added is large, the pores between the particles become small, and a sufficient ink absorption rate may not be obtained. On the other hand, when the amount of the binder is small, the ink receiving layer may be cracked.

The binder is preferably cross-linked by the cross-linking agent because it can further reduce the occurrence of cracks and further improve ink absorbability, glossiness, image quality, and the like.
The cross-linking agent may be blended in advance in the coating liquid for forming the ink receiving layer, or the cross-linking agent solution may be applied before coating the ink receiving layer or after coating the ink receiving layer.
The coating amount of the crosslinking agent, preferably ^{0.01~1.0g / m 2, 0.05~0.5g / m} 2 is more preferable. If it is less than 0.01 g / m ² , the effect of preventing cracking will be low, and if it exceeds 1.0 g / m ² , cracking may occur due to strong shrinkage during drying of the ink receiving layer, or ink absorption may be reduced. There is a risk.

<Other ingredients>
In the ink receiving layer, in order to further improve the heat and moisture resistance, aluminum compounds such as basic aluminum chloride, basic aluminum sulfate, basic fatty acid aluminum, etc., or zirconyl chloride, basic zirconyl chloride, zirconyl nitrate, zirconyl fatty acid, etc. The zirconium compound can also be contained.
Specific examples of fatty acids in basic fatty acid aluminum, fatty acid zirconyl and the like include, for example, formic acid, acetic acid, propionic acid, butanoic acid, glycolic acid, 3-hydroxypropionic acid, 4-hydroxybutanoic acid, glycine, β-alanine, 4 -Aminobutanoic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid and the like. Of these, acetic acid is particularly preferred.

In addition, the ink receiving layer is used for the purpose of improving storage stability such as light resistance and gas resistance, for example, phenolic antioxidants, hindered amine light stabilizers, benzotriazole ultraviolet absorbers, sulfur compounds, water-soluble metals. You may contain salt etc.
Further, in the ink receiving layer, various known pigment dispersants, thickeners, fluidity modifiers, antifoaming agents, foam inhibitors, mold release agents, foaming agents, penetrating agents, colored dyes, colored pigments, fluorescent Brightening agents, preservatives, antifungal agents and the like may be included as appropriate.

  The ink receiving layer may be composed of a single layer, or may be composed of a plurality of layers including an inner ink receiving layer and an outer ink receiving layer.

<Hindered amine light stabilizer>
The ink jet recording sheet contains a specific hindered amine light stabilizer. The hindered amine light stabilizer may be contained in any part of the ink jet recording sheet, but the specific hindered amine light stabilizer is contained in the ink receiving layer or on the ink receiving layer or the ink receiving layer. And the support.

  Here, the hindered amine light stabilizer is at least one structural unit (b1) represented by the following general formula (3), and at least represented by the following general formula (4) and / or general formula (5). It is a polymer (B) containing 1 type of structural unit (b2).

In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁸ , and R ⁹ each independently represent a hydrogen atom and an alkyl group having 1 to 8 carbon atoms, and R ^{5 to} R ⁷ each independently represent a carbon number. 1 to 8 represents an alkyl group, Z represents an acid residue, and n represents an integer of 1 to 6. R ¹⁰ and R ¹¹ each independently represents an oxygen atom or N—R ¹⁴ . Here, R ¹⁴ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. R ¹² and R ¹³ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.
Specific examples of the alkyl group having 1 to 8 carbon atoms include methyl, ethyl, n-propyl, i-propyl, butyl, pentyl, hexyl, octyl and the like.

  Z in the general formula (4) is an acid residue. Specific examples of the acid residue represented by Z may be an inorganic acid or an organic acid. Examples of the inorganic acid include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, pyrophosphoric acid, metaphosphoric acid, and the like. , Formic acid, acetic acid, propionic acid, methanesulfonic acid, p-toluenesulfonic acid and the like. These can be used alone or in combination of two or more. Among these acid residues, hydrochloric acid and sulfuric acid are preferable because the effect of improving image storage stability is particularly excellent.

In the general formula (5), specific examples of —R ¹⁰ —R ¹² and —R ¹¹ —R ¹³ include —CO—OH, —CO—ONa, —CO—NH, —NH—H, —NH—CH. ₃ etc. are mentioned.

  The structural unit (b2) is preferably a structural unit represented by the following general formula (8) because the production of a hindered amine light stabilizer is facilitated and the coating stability is increased.

In the formula, R ¹⁵ and R ¹⁶ each independently represent a hydrogen atom or a methyl group. R ^{17 to} R ¹⁹ each independently represents an alkyl group having 1 to 3 carbon atoms.
W represents an acid residue. Among the acid residues, halogen atoms, particularly Br ⁻ and Cl ⁻ are preferable from the viewpoints of water solubility, paint stability, image quality, light fastness and the like.

  In this hindered amine light stabilizer, the molar ratio of the structural unit (b1) to the structural unit (b2) is preferably 10: 1 to 1: 2. If the content of the structural unit (b1) is lower than this range, the effect as a light stabilizer may be insufficient, and if the content of the structural unit (b2) is lower than this range, the hydrophilicity decreases, so that the inkjet There is a tendency for the image quality of the recording to decrease.

  The molecular weight of the hindered amine light stabilizer is preferably 1,000 to 500,000, and more preferably 5,000 to 100,000. If the molecular weight is within this range, the coating stability will be good, high image quality will be obtained, storage stability such as light resistance and heat and humidity resistance, and ink absorption will be high, and cracks can be further prevented.

The content of the hindered amine light stabilizer in the inkjet recording sheet is preferably 0.01 to 10 g / m ² , and more preferably 0.05 to 5 g / m ² . Within this range, the image quality, image storability and ink absorbability are excellent.

  The ink receiving layer may be composed of a single layer, or may be composed of a plurality of layers including an inner ink receiving layer and an outer ink receiving layer.

≪Other composition≫
<Glossy layer>
In the present invention, a cast gloss layer may be further formed on the above-described ink receiving layer. Thereby, an ink jet recording sheet having a higher surface gloss can be obtained.
The gloss layer is configured to contain fine particles and / or a resin. The gloss layer is preferably made porous or liquid-permeable so long as it does not impair the gloss so that the ink can pass or absorb quickly.

The fine particles used in the gloss layer include those similar to the inorganic fine particles used in the ink receiving layer, but colloidal silica, amorphous silica, alumina, aluminosilicate in terms of gloss, transparency and ink absorbability. Zeolite, synthetic smectite and the like are preferable.
The average particle diameter of the fine particles (in the case of aggregated particles, the diameter of the aggregated particles) is preferably 0.001 to 1 μm, and more preferably 0.005 to 0.5 μm. If the particle diameter is within this range, excellent ink absorbability, gloss and print density can be obtained.
The fine particle content in the glossy layer is preferably 10 to 90% by mass.

  Examples of resins used for the gloss layer include water-soluble binders (for example, polyvinyl alcohols such as polyvinyl alcohol, cation-modified polyvinyl alcohol, and silyl-modified polyvinyl alcohol, casein, soy protein, synthetic proteins, starch, cellulose such as carboxymethyl cellulose and methyl cellulose). Derivatives), styrene-butadiene copolymer, conjugated diene polymer latex such as methyl methacrylate-butadiene copolymer, water-dispersible resin such as vinyl copolymer latex such as styrene-vinyl acetate copolymer, aqueous acrylic Various resins (adhesives) known and used in general in the field of coated paper, such as resins, water-based polyurethane resins, water-based polyester resins, etc., can be used alone or in combination.

When the gloss layer is mainly formed of a resin, the resin is a polymer or copolymer (hereinafter collectively referred to as a polymer) obtained by polymerizing a monomer having an ethylenically unsaturated bond (hereinafter referred to as an ethylenic monomer). The main component is preferably a main component. Furthermore, substituted derivatives of these polymers may be used.
In addition, the above ethylenic monomer is polymerized in the presence of colloidal silica, and the composite is formed by Si—O—R (R: polymer component) bond, or the polymer is colloidal silica such as SiOH group and the like. A functional group capable of reacting may be introduced and used in the form of a composite by reacting with colloidal silica. When such a composite is used, it tends to be excellent in gloss and ink absorbability.

It is preferable that a release agent is further blended in the glossy layer. As the release agent, various publicly known release agents generally used in the coated paper field can be used.
In addition, the glossy layer can be mixed with the above cationic compounds to increase print density, improve water resistance, or add various auxiliaries to improve light resistance and gas resistance. It is.

In the ink jet recording sheet of the present invention, an intermediate layer is provided between the support and the ink receiving layer, a protective layer is provided on the back surface (the surface where the ink receiving layer is not formed) of the support, It can also be adhesively processed on the back side.
In addition, the ink jet recording sheet of the present invention may contain various other known fastness improvers other than the specific hindered amine light stabilizer within the range not inhibiting the present invention.

≪Manufacturing method≫
In the manufacturing method of the said inkjet recording sheet, various methods can be taken except coating the coating liquid containing an inorganic fine particle, a cationic polymer, and a solvent on a support body. For example, as a method of including the cationic polymer in the ink receiving layer, a method of adding the cationic polymer to the coating liquid, or an aqueous solution containing the cationic polymer before the coating liquid is applied to a support. And a method of coating an aqueous solution containing the cationic polymer on the support after coating the coating solution on a support. Further, as a method of including the hindered amine light stabilizer in the ink receiving layer, a method of adding the hindered amine light stabilizer to the coating liquid, and the hindered amine system before applying the coating liquid to a support. Examples thereof include a method of coating a liquid containing a light stabilizer on a support, a method of coating the liquid containing the above hindered amine light stabilizer on the support, and the like.

  Specifically, when the ink receiving layer is composed of a single layer, a method of coating an ink receiving layer forming coating solution containing inorganic fine particles, a cationic polymer, a binder, and a hindered amine light stabilizer on a support. Is taken.

When the ink receiving layer is formed of a plurality of layers, for example, the following production method can be adopted. That is, after applying a first ink-receiving layer-forming coating liquid containing inorganic fine particles and a binder to the support to form at least one inner ink-receiving layer, on the inner ink-receiving layer, At least one layer is formed by applying a light stabilizer-containing liquid containing the hindered amine light stabilizer and coating a second ink-receiving layer-forming liquid containing inorganic fine particles and a binder thereon. In this method, the light stabilizer-containing liquid or the second ink-receiving layer-forming coating liquid may further contain a cationic polymer containing the polymer (A). According to this method, the heat and moisture resistance of the image can be further improved, and cracks can be further prevented.
It is also possible to produce an ink jet recording sheet having a plurality of ink receiving layers by methods other than the above methods.

In the above method, it is preferable that the light stabilizer-containing liquid contains a cross-linking agent from the viewpoint of heat and moisture resistance of images and suppression of cracks.
Specific examples of the crosslinking agent include, for example, boron compounds such as boric acid, borax, and borate, glyoxal, melamine / formaldehyde, glutaraldehyde, methylol urea, polyisocyanate compound, epoxy compound, aziridine compound, carbodiimide compound, dihydrazide A compound, an aluminum compound, a zirconium compound, etc. are mentioned. Of these, boron compounds are preferable, and borax is particularly preferable.
Furthermore, since the pH of the light stabilizer-containing liquid containing a crosslinking agent can prevent cracking more, it is preferably 7.0 to 10.0, more preferably 7.5 to 9.0, depending on the alkali such as sodium hydroxide. It is better to use it after adjusting.

At this time, the coating amount of the crosslinking agent, preferably ^{0.01~1.0g / m 2, 0.05~0.5g / m} 2 is more preferable. If it is less than 0.01 g / m ² , the effect of preventing cracking tends to be low, and if it exceeds 1.0 g / m ² , the ink receiving layer may be cracked due to strong shrinkage during drying, or ink absorptivity may be reduced. May decrease.
Moreover, as mass ratio of a crosslinking agent and a cationic polymer, 1: 1-1: 20 are preferable and 1: 1-1: 10 are more preferable. If the mass ratio is in the above range, cracks can be further prevented, and aging resistance and ink absorbability can be increased.

The solvent contained in the ink-receiving layer-forming coating liquid is preferably water or an aqueous solvent containing water and alcohol.
The ink receiving layer forming coating solution preferably contains a phosphorus oxoacid salt as a paint stabilizer. Specific examples thereof include alkali metal salts such as phosphoric acid, phosphorous acid, hypophosphorous acid, metaphosphoric acid, metaphosphorous acid, pyrophosphoric acid, pyrophosphorous acid, and polyphosphoric acid, alkaline earth metal salts, and ammonium salts. And zinc salts.
Of these, hypophosphite is preferable because it is particularly effective in coating stability. Specific examples of hypophosphites include, for example, sodium hypophosphite, potassium hypophosphite, calcium hypophosphite, magnesium hypophosphite, barium hypophosphite, ammonium hypophosphite, hypophosphorous acid. Zinc acid etc. are mentioned. Of these, sodium hypophosphite is particularly preferable because it has the highest effect on paint stability.

  Examples of the coating method for the ink receiving layer forming coating liquid include coating methods such as a bar coater, a blade coater, an air knife coater, a gravure coater, a die coater, and a curtain coater.

When the ink receiving layer is composed of one layer, the coating amount of the ink receiving layer forming coating liquid is preferably ² to 50 g / m ² in terms of dry mass, and preferably 3 to 30 g / m ^2. More preferred. When the coating amount is within this range, the recording image quality and the coating film strength are excellent.
When the ink receiving layer is composed of a plurality of layers, the coating amount of the inner ink receiving layer and the coating amount of the outer ink receiving layer are each ² to 50 g / m ² in dry mass. Is preferable, and it is more preferable that it is 5-30 g / m < ² >.

In order to increase the surface glossiness of the ink receiving layer after application of the ink receiving layer forming coating liquid, the ink receiving layer forming coating liquid (coating layer) applied on the support is in a wet state. The coating layer may be casted.
As a method for the casting treatment, there are a wet method, a gelation method, and a rewet method. The wet method is a method in which the coated layer is pressed against the heated mirror drum surface while the coated layer is in a wet state to perform a high gloss finish. The gelation method is a method in which the coating layer is brought into contact with a gelling agent bath while the coating layer is in a wet state, and the coating layer in the gelled state is pressed against the surface of the heating drum to perform a high gloss finish. It is. The rewetting method is a method in which a wet coating layer is once dried and then brought into contact with a wetting liquid again, and then pressed against the surface of a heated drum to perform a high gloss finish.
When the ink receiving layer is cast, it is preferable that a release agent is blended in the ink receiving layer forming coating solution. As the release agent, various publicly known release agents generally used in the coated paper field can be used.

  Furthermore, for the purpose of imparting high gloss after the ink receiving layer is formed, for example, it is possible to provide surface smoothness through the roll nip under pressure with a super calender, gloss calender, soft calender or the like.

Further, when a gloss layer is formed on the ink receiving layer, a gloss layer coating liquid containing fine particles and / or resin is applied onto the ink receiving layer to form a coating layer, Cast the layer and dry.
The coating amount of the glossy layer coating liquid for a dry weight is preferably 0.1 to 30 g / ^{m 2,} and more preferably 0.2 to 10 g / ^{m 2.} When the coating amount of the gloss layer coating liquid is within this range, the gloss, ink drying property, and recording density are excellent.
The same method as described for the ink receiving layer can be applied to the coating and casting of the gloss layer coating solution.
The drying temperature of the gloss layer is also important. If the drying temperature is too high, the film formation proceeds too much, the surface porosity decreases, and the ink absorption rate tends to decrease. On the other hand, if the drying temperature is too low, the gloss tends to be poor and the productivity is also lowered. Therefore, the drying temperature is preferably 50 to 150 ° C, more preferably 70 to 120 ° C.

  The ink jet recording sheet described above includes a specific cationic polymer and a specific hindered amine light stabilizer, so that the crack of the ink receiving layer is greatly improved and long-term storage (light resistance) Excellent in water resistance, water resistance and heat and humidity resistance.

The liquid ink for forming a recorded image on the inkjet recording sheet of the present invention is a recording liquid comprising a colorant, a liquid medium, and other optional additives, and any commercially available inkjet recording liquid ink is used. it can.
Examples of the colorant include various water-soluble dyes such as direct dyes, acid dyes, and reactive dyes, carbon black finely divided around 100 nm, and surface-treated with a resin, a surfactant, and the like, organic pigments, and the like.
The liquid medium includes water alone or a combination of water and a water-soluble organic solvent. Examples of water-soluble organic solvents include monohydric alcohols such as ethyl alcohol and isopropyl alcohol, 1,2-hexanediol, polyhydric alcohols such as ethylene glycol, diethylene glycol, polyethylene glycol, and glycerin, triethylene glycol monomethyl ether, and triethylene glycol. And lower alkyl ethers of polyhydric alcohols such as monoethyl ether.
Among them, the pigment ink contains 1,2-hexanediol and glycerin as water-soluble organic solvents in the pigment ink, and the total of both is 80% or more of the water-soluble solvent, and the inkjet recording sheet of the present invention. This combination is suitable from the standpoint of suitability for pigment ink, particularly scratch resistance.
Examples of the additive include a pH adjuster, a metal sequestering agent, an antifungal agent, a viscosity adjuster, a surface tension adjuster, a surfactant, and a rust preventive agent.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. In the examples, “parts” and “%” respectively represent “parts by mass” and “% by mass” unless otherwise specified.

Example 1
(Preparation of coating liquid A for forming an ink receiving layer)
Gas phase method silica (trade name: Aerosil 300, average particle size of primary particles; 7 nm, specific surface area by BET method: 300 m ² / g, manufactured by Nippon Aerosil Co., Ltd.), 100 parts of polyamidine cationic polymer (trade name: High 25 parts of 35% aqueous solution of Max SC-700M, mass average molecular weight of about 20,000, manufactured by Hymo Co., Ltd.) and 775 parts of ion-exchanged water were mixed. The resulting mixture was dispersed with a stirrer and then processed using a wet ultra-fine atomizer Nanomizer. Next, 40 parts of a 10% aqueous solution of a hindered amine compound I represented by the following general formula (9) (molecular weight; about 15,000, l: m = 2: 1), polyvinyl alcohol ( Product name: PVA-145, manufactured by Kuraray, saponification degree 99%, average degree of polymerization 4,500) 5% aqueous solution 400 parts and a small amount of antifoaming agent, dispersant and water were added, and the solid content concentration was 8%. A coating liquid A for forming an ink receiving layer was obtained.

(Preparation of ink receiving layer forming coating solution B)
Wet process synthetic amorphous silica 20% dispersion (trade name: Silojet 703A, manufactured by Grace Devison) 500 parts, polyvinyl alcohol (trade name: PVA-145, manufactured by Kuraray Co., Ltd.) 400% 5% aqueous solution and A small amount of an antifoaming agent, a dispersing agent and water were mixed to obtain a coating liquid B for forming an ink receiving layer having a solid content concentration of 15%.

(Manufacture of inkjet recording sheets)
The ink receiving layer-forming coating solution B is dried on a paper support (thickness 240 μm, polyethylene resin contains 15% by mass of anatase-type titanium dioxide) on both sides of a 180 g / m ² base paper with polyethylene resin. The ink receiving layer B was formed by applying and drying with a wire bar so as to be 20 g / m ² . Next, after applying a 0.5% borax aqueous solution at 20 g / m ² onto the ink receiving layer B, the ink receiving layer forming coating liquid A is applied thereon so that the dry mass becomes 10 g / m ^2. The ink receiving layer A was formed by applying and drying with a wire bar to obtain an ink jet recording sheet.

Example 2
In Example 1, instead of the hindered amine compound I, the hindered amine compound II represented by the general formula (9) (molecular weight: about 15,000, l: m = 1: 1) was used. An ink jet recording sheet was obtained in the same manner as in Example 1.

Example 3
In Example 1, instead of 25 parts of 35% aqueous solution of a polyamidine cationic polymer (trade name: Himax SC-700M, mass average molecular weight of about 20,000, manufactured by Hymo Co., Ltd.), a polyallylamine cationic polymer (trade name) : PAA-HCl-3L, mass average molecular weight of about 10,000, manufactured by Nittobo Co., Ltd.), except that 20 parts of a 40% aqueous solution was used, an ink jet recording sheet was obtained in the same manner as in Example 1.

Example 4
In Example 2, instead of 25 parts of 35% aqueous solution of polyamidine-based cationic polymer (trade name: Himax SC-700M, molecular weight of about 20,000, manufactured by Hymo Co., Ltd.), polyallylamine-based cationic polymer (trade name: PAA) An inkjet recording sheet was obtained in the same manner as in Example 2 except that 20 parts of a 40% aqueous solution of -HCl-3L, mass average molecular weight of about 10,000, manufactured by Nitto Boseki Co., Ltd. was used.

Example 5
(Preparation of silica fine particle dispersion)
Distilled water was added to a sodium silicate solution having a SiO ₂ concentration of 30% by mass and SiO ₂ / Na ₂ O (molar ratio) of 3.1 (manufactured by Tokuyama Corp., No. 3 sodium silicate) to obtain a SiO ₂ concentration of 4.0. A mass% dilute sodium silicate aqueous solution was prepared. This dilute sodium silicate aqueous solution was passed through a column filled with a hydrogen-type cation exchange resin (manufactured by Mitsubishi Chemical Corporation, Diaion SK-1BH) to prepare an active silicic acid aqueous solution.
Next, 500 g of distilled water was charged into a 5 liter glass reaction vessel equipped with a refluxer, a stirrer, and a thermometer, heated to 100 ° C., and then kept at 100 ° C., the active silicic acid aqueous solution prepared earlier was 1. 450 g was added at a rate of 5 g / min to prepare a seed solution. The average secondary particle diameter of the seed particle aggregate in the seed solution was 184 nm.
Next, 0.9 g of 28% aqueous ammonia solution was added to the seed solution for stabilization, and then 550 g of active silicic acid aqueous solution was added at 100 ° C. at a rate of 1.5 g / min. After completion of the addition, the mixture was heated to reflux at 100 ° C. for 9 hours and then concentrated to obtain a 10% by mass silica fine particle dispersion. The silica fine particles had an average primary particle diameter of 11 nm, an average secondary particle diameter of 130 nm, a specific surface area of 257 m ² / g by BET method, and a pore volume of 1.01 ml / g.

(Preparation of ink-receiving layer-forming coating solution C)
25 parts of a 35% aqueous solution of a polyamidine-based cationic polymer (trade name: Himax SC-700M, mass average molecular weight of about 20,000, manufactured by Hymo Co., Ltd.) is added to 1000 parts of the 10% by mass silica fine particle dispersion, followed by stirring. After being dispersed by the apparatus, it was processed using a wet ultrafine atomizer Nanomizer. In the treatment solution thus obtained, 40 parts of a 10% aqueous solution of hindered amine compound I, polyvinyl alcohol (trade name: PVA-145, manufactured by Kuraray Co., Ltd., saponification degree 99%, average polymerization degree 4,500) 389 parts of a 5% aqueous solution and a small amount of an antifoaming agent, a dispersing agent and water were added to obtain a coating liquid C for forming an ink receiving layer having a solid concentration of 8%.

(Manufacture of inkjet recording sheets)
An ink jet recording sheet was obtained in the same manner as in Example 1, except that the ink receiving layer forming coating liquid C was applied instead of the ink receiving layer forming coating liquid A to form the ink receiving layer C.

Example 6
(Manufacture of inkjet recording sheets)
On a paper support (thickness 240 μm, polyethylene resin containing 15% by mass of anatase-type titanium dioxide) on both sides of a 180 g / m ² base paper, a 7% borax water coating solution is 20 g / m ^2. It was applied with. Next, the ink receiving layer-forming coating liquid A was applied thereon with a wire bar so as to have a dry mass of 20 g / m 2 and dried to form the ink receiving layer A to obtain an ink jet recording sheet. .

Example 7
(Preparation of coating liquid D for ink receiving layer formation)
Gas phase method silica (trade name: Aerosil 300, manufactured by Nippon Aerosil Co., Ltd.) 100 parts, polyamidine-based cationic polymer (trade name: Himax SC-700M, mass average molecular weight of about 20,000, manufactured by Hymo Co., Ltd.) A 25% aqueous solution and 775 parts ion-exchanged water were mixed. The resulting mixture was dispersed with a stirrer and then processed using a wet ultra-fine atomizer Nanomizer. Next, 360 parts of 5% aqueous solution of polyvinyl alcohol (trade name: PVA-145, manufactured by Kuraray Co., Ltd., saponification degree 99%, average polymerization degree 4,500) and a small amount of antifoaming agent were added to the obtained treatment liquid. Then, a dispersant and water were added to obtain an ink receiving layer forming coating solution D having a solid concentration of 8%.

(Manufacture of inkjet recording sheets)
The ink receiving layer forming coating liquid B is 20 g in dry weight on a paper support (thickness 240 μm, polyethylene resin containing 15% by mass of anatase-type titanium dioxide) on both sides of a 180 g / m ² base paper. The ink receiving layer B was formed by applying and drying with a wire bar so as to be / m ² . Next, an borax-hindered amine compound I aqueous solution (1: 5 mixed solution, concentration 3%) was applied onto the ink receiving layer B at 20 g / m ² . On top of that, the ink receiving layer D was formed by applying and drying the ink receiving layer forming coating solution D with a wire bar so that the dry mass was 7 g / m ² , thereby obtaining an ink jet recording sheet.

Example 8
In Example 7, an ink jet recording sheet was obtained in the same manner as in Example 1 except that the hindered amine compound II was used instead of the hindered amine compound I.

Example 9
(Preparation of coating liquid E for ink receiving layer formation)
Wet process synthetic amorphous silica (trade name: Fine Seal X-30, manufactured by Tokuyama Co., Ltd.) 100 parts, silicon-modified polyvinyl alcohol (trade name: R-1130, manufactured by Kuraray Co., Ltd., degree of saponification 98.5) %, Average polymerization degree 3,000) 10% aqueous solution and a small amount of an antifoaming agent, a dispersing agent and water were mixed to prepare an ink receiving layer forming coating solution E having a solid content concentration of 15%.

(Manufacture of inkjet recording sheets)
Dry weight of the ink receiving layer coating liquid E in fine paper of 200 g / m ² is coated by a wire bar such that the 10 g / m ^2, and dried to form an ink-receiving layer E. Next, a 7% borax aqueous solution was applied onto the ink receiving layer E at 20 g / m ² , and then the ink receiving layer forming coating solution A was applied to the wire bar so that the dry mass was 15 g / m 2. The ink receiving layer F was formed by coating and drying.

Example 10
(Preparation of gloss layer coating solution F)
Colloidal Silka (trade name: Snowtex ST-OL, manufactured by Nissan Chemical Industries, Ltd.) 100 parts, ammonium oleate (trade name: DEF-116T, manufactured by Nisshin Chemical Laboratory Co., Ltd.) 2 as a release agent A gloss layer coating solution F having a solid content concentration of 5% was prepared.

(Manufacture of inkjet recording sheets)
In the same manner as in Example 1, an ink receiving layer B and an ink receiving layer A were sequentially formed on a paper support. Next, after the coating liquid F for the glossy layer is further coated on the ink receiving layer A with a wire bar, the coated surface is immediately pressed against a mirror drum having a surface temperature of 95 ° C., dried and then released to give a gloss. Layer F was formed to obtain an inkjet recording sheet. The coating amount of the gloss layer F at this time was 1 g / m ² in terms of solid content.

(Preparation of borax-containing liquid G containing cationic polymer)
Dissolve 100 parts of a 40% aqueous solution of polyallylamine-based cationic polymer (trade name: PAA-D41-HCL, mass average molecular weight of about 20,000, manufactured by Nitto Boseki Co., Ltd.), 16 parts of borax and 17 parts of sodium hydroxide in water. Then, a borax-containing liquid G containing a cationic polymer having a solid content concentration of 4.3% and a pH of 8.6 was prepared.

Example 11
(Manufacture of inkjet recording sheets)
In the same manner as in Example 1, an ink receiving layer B was formed on a paper support, and a borax-containing liquid G was applied onto the ink receiving layer B at 20 g / m ² . Next, the ink receiving layer forming coating liquid A was applied thereon with a wire bar so that the dry mass was 10 g / m ² and dried to form the ink receiving layer A to obtain an ink jet recording sheet. .

Example 12
(Manufacture of inkjet recording sheets)
In Example 11, instead of 25 parts of 35% aqueous solution of a polyamidine cationic polymer (trade name: Himax SC-700M, mass average molecular weight of about 20,000, manufactured by Hymo Co., Ltd.), a polyallylamine cationic polymer (trade name) : PAA-HCl-3L, mass average molecular weight about 10,000, manufactured by Nittobo Co., Ltd.), except that 20 parts of a 40% aqueous solution was used to obtain an ink jet recording sheet in the same manner as in Example 11.

Comparative Example 1
An ink jet recording sheet was obtained in the same manner as in Example 1 except that the hindered amine compound I was not contained in the ink receiving layer forming coating liquid A in Example 1.

Comparative Examples 2-3
In Example 1, an inkjet recording sheet was obtained in the same manner as in Example 1 except that the following compound was used instead of the hindered amine compound I.
Comparative Example 2: Hindered amine compound III (trade name ADK STAB LA-52, manufactured by Asahi Denka Kogyo) 4 parts Comparative Example 3: Hindered amine compound IV (trade name ADK STAB LA-77, manufactured by Asahi Denka Kogyo) 4 parts

Comparative Example 4
In Example 1, instead of polyamidine-based cationic polymer, 28 parts of 31% aqueous solution of diallyldimethylammonium chloride-based cationic polymer (trade name: Unisense CP-101, mass average molecular weight of about 20,000, manufactured by Senca Co., Ltd.) is included. An ink jet recording sheet was obtained in the same manner as in Example 1 except that the ink receiving layer forming coating solution H was used.

Comparative Example 5
In Example 1, instead of the polyamidine cationic polymer, 28 parts of 31% aqueous solution of diallyldimethylammonium chloride cationic polymer (trade name: Unisense CP-101, mass average molecular weight of about 20,000, manufactured by Senka Co., Ltd.) An ink jet recording sheet was obtained in the same manner as in Example 1, except that the ink receiving layer forming coating liquid I containing the hindered amine compound III was used instead of the hindered amine compound I.

(Evaluation methods)
For the ink jet recording sheets obtained in Examples 1 to 10 and Comparative Examples 1 to 5, an Epson ink jet printer PM-950C (dye ink system) was used, and an ISO-400 image (“high-definition color digital standard image data ISO / JIS) was used. -SCID ", p13, image name: portrait, issued by the Japanese Standards Association) and solid printing so that the optical density of composite black was 1.0. The obtained inkjet recording sheet and its image were evaluated as follows, and the results are shown in Table 1.

[Glossy]
The glossiness of the ink-jet recording sheet coated surface of the unprinted portion was visually observed and evaluated.
(Evaluation criteria)
◎: Gloss is very high and good ○: Gloss is high and good △: Gloss is slightly inferior ×: Gloss is almost absent

〔crack〕
The cracked state of the ink-jet recording sheet coated surface of the unprinted part was visually observed and evaluated.
(Evaluation criteria)
◎: No cracks are observed ○: Some cracks are observed but there is no problem △: Cracks are observed and there are practical problems ×: There are many cracks

[Ink absorbency]
The obtained ISO-400 image was visually observed to evaluate ink absorbency.
(Evaluation criteria)
◎: Image collapse due to ink overflow is not observed at all ○: Image collapse due to ink overflow is slightly observed, but at a level that is not a problem for practical use Δ: Image collapse due to ink overflow is observed with practical problem × : Significant ink overflow

〔image quality〕
The image quality of the obtained ISO-400 image was visually observed and evaluated.
(Evaluation criteria)
◎: Image quality is very good ○: Image quality is good and practically no problem △: Image quality is inferior and practically problematic ×: Image quality is very inferior

[Heat resistance]
The obtained ISO-400 image and the solid black solid print image were allowed to stand for 24 hours and then stored in a constant temperature and humidity chamber at 40 ° C. and 90% relative humidity for 72 hours. The heat and humidity resistance was evaluated by visual observation after storage.
(Evaluation criteria)
A: Occurrence of blurring and discoloration over time is good, and it is good. ○: Slight blurring and discoloration over time are observed, but there is no practical problem at all. Δ: Bending over time and discoloration are observed. X which is a problem level in practical use x: A blurring with time is remarkably recognized, and a discoloration is also remarkable.

[Light resistance]
The obtained ISO-400 image and a solid black printed image of the composite black were allowed to stand for 24 hours, and then used in an atmosphere of 63 ° C. and relative humidity of 40% using a xenon weather meter (Model SEL Tester WEL-7X-LHP). And stored for 48 hours. The image after storage was visually observed to evaluate light resistance.
(Evaluation criteria)
A: Almost no discoloration is observed and very good. ○: Slight discoloration is observed, but the color balance is not broken. Good: Discoloration is observed, which is a practically problematic level. X: Discoloration is remarkable.
For solid black printed images, the optical density before and after storage in a xenon weather meter was measured with a Macbeth reflection densitometer RD-914, and the residual ratio [(optical density after storage / optical density before storage) × 100 (%)].

As apparent from Table 1, the inkjet recording sheets of Examples 1 to 12 containing a specific cationic polymer in the ink-receiving layer and containing a specific hindered amine light stabilizer have gloss and ink absorbability. An excellent image with no cracks and high quality was formed. Further, even under high temperature and high humidity, there was almost no occurrence of blurring or discoloration over time, and the heat and humidity resistance was excellent. Furthermore, even when exposed to light for a long period of time, the image has very little discoloration and excellent light resistance. That is, the ink jet recording sheet was excellent in long-term storage stability.
In contrast, the inkjet recording sheet of Comparative Example 1 that did not contain a specific hindered amine light stabilizer had low light resistance.
In addition, the ink jet recording sheet of Comparative Example 2 containing no hindered amine light stabilizer and containing hindered amine compound III and the ink jet recording sheet of Comparative Example 3 containing hindered amine compound IV are cracked. However, gloss, ink absorbency, and image quality were low.
The ink jet recording sheet of Comparative Example 4 in which the ink-receiving layer did not contain a specific cationic polymer produced blurring under high temperature and high humidity, and had low heat and moisture resistance and light resistance.
The inkjet recording sheet of Comparative Example 5 in which the ink receiving layer does not contain a specific cationic polymer and a specific hindered amine light stabilizer is cracked, and all of gloss, ink absorptivity, image quality, heat and humidity resistance, and light resistance Was low.

Claims (10)

On the support, an ink receiving layer containing inorganic fine particles, a cationic polymer and a binder is formed, and in the ink jet recording sheet containing a hindered amine light stabilizer,
The polymer in which the cationic polymer has at least one structural unit (a1) represented by the following general formula (1) or at least one structural unit (a2) represented by the following general formula (2) ( A), including

[Wherein, X represents an acid residue. ]

[Wherein Y represents an acid residue. ]
The hindered amine light stabilizer is at least one structural unit (b1) represented by the following general formula (3), and at least one structural formula (4) and / or general formula (5). An ink jet recording sheet comprising a polymer (B) containing the structural unit (b2).

[Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁸ , R ⁹ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ^{5 to} R ⁷ each independently represent carbon. The alkyl group of number 1-8 is represented, Z represents an acid residue, n represents the integer of 1-6. R ¹⁰ and R ¹¹ each independently represents an oxygen atom or N—R ¹⁴ . Here, R ¹⁴ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. R ¹² and R ¹³ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. ] The ink jet recording sheet according to claim 1, wherein the polymer (A) contained in the cationic polymer further comprises at least one structural unit (a3) represented by the general formula (6).

The ink jet recording sheet according to claim 1, wherein the polymer (A) contained in the cationic polymer further comprises at least one structural unit (a4) represented by the general formula (7).

The inkjet recording sheet according to claim 1, wherein the structural unit (b2) is a structural unit represented by the following general formula (8).

[Wherein, R ¹⁵ and R ¹⁶ each independently represents a hydrogen atom or a methyl group. R ^{17 to} R ¹⁹ each independently represents an alkyl group having 1 to 3 carbon atoms. W represents an acid residue. ]   The inkjet recording sheet according to any one of claims 1 to 4, wherein the average primary particle diameter of the inorganic fine particles is 30 nm or less. An ink jet recording sheet manufacturing method comprising: forming an ink receiving layer by coating an ink receiving layer forming coating solution containing inorganic fine particles, a cationic polymer, a binder, and a hindered amine light stabilizer on a support. ,
The polymer in which the cationic polymer has at least one structural unit (a1) represented by the following general formula (1) or at least one structural unit (a2) represented by the following general formula (2) ( A), including

[Wherein, X represents an acid residue. ]

[Wherein Y represents an acid residue. ]
The hindered amine light stabilizer is at least one structural unit (b1) represented by the following general formula (3), and at least one kind represented by the following general formula (4) and / or general formula (5). A method for producing an inkjet recording sheet, which is a polymer (B) containing the structural unit (b2).

[Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁸ , R ⁹ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ^{5 to} R ⁷ each independently represent carbon. The alkyl group of number 1-8 is represented, Z represents an acid residue, n represents the integer of 1-6. R ¹⁰ and R ¹¹ each independently represents an oxygen atom or N—R ¹⁴ . Here, R ¹⁴ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. R ¹² and R ¹³ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. ] A first ink-receiving layer-forming coating liquid containing inorganic fine particles and a binder, a light stabilizer-containing liquid containing a hindered amine light stabilizer, and a second ink containing inorganic fine particles and a binder on a support. A method for producing an ink jet recording sheet, in which an ink receiving layer is formed by sequentially applying a receiving layer forming coating liquid,
The light stabilizer-containing liquid or the second ink-receiving layer-forming coating liquid further contains a cationic polymer, and the cationic polymer contains at least one structural unit (a1) represented by the following general formula (1): Or a polymer (A) having at least one structural unit (a2) represented by the following general formula (2):

[Wherein, X represents an acid residue. ]

[Wherein Y represents an acid residue. ]
The hindered amine light stabilizer is at least one structural unit (b1) represented by the following general formula (3), and at least one structural formula (4) and / or general formula (5). A method for producing an inkjet recording sheet, which is a polymer (B) containing the structural unit (b2).

[Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁸ , R ⁹ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ^{5 to} R ⁷ each independently represent carbon. The alkyl group of number 1-8 is represented, Z represents an acid residue, n represents the integer of 1-6. R ¹⁰ and R ¹¹ each independently represents an oxygen atom or N—R ¹⁴ . Here, R ¹⁴ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. R ¹² and R ¹³ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. ]   The method for producing an inkjet recording sheet according to claim 7, wherein the light stabilizer-containing liquid further contains a crosslinking agent. The method for producing an inkjet recording sheet according to any one of claims 6 to 8, wherein the polymer (A) contained in the cationic polymer further comprises at least one structural unit (a3) represented by the general formula (6). .

The method for producing an inkjet recording sheet according to any one of claims 6 to 8, wherein the polymer (A) contained in the cationic polymer further comprises at least one structural unit (a4) represented by the general formula (7). .