JP2009241290A - Inkjet recording sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording sheet excellent in glossiness, ink absorbing properties, image quality, long term storing properties, and especially excellent in image storing properties under high temperature and high humidity conditions. <P>SOLUTION: In the inkjet recording sheet having at least one layer of ink receiving layer comprising an inorganic fine particle and a binder on a substrate, the inkjet recording sheet is characterized by containing a surface modified inorganic fine particle A with a mean primary particle diameter of ≤30 nm, and the surface of which is modified with at least one of amino-organosilane, and a surface modified inorganic fine particle B with a mean primary particle diameter of ≤30 nm, and the surface of which is modified with at least one of cationic polymer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ink jet recording sheet having an ink receiving layer containing inorganic fine particles and a binder on a support.

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 or form printing because it is less expensive than the device.
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 an ink jet recording sheet having both image quality and storability comparable to a silver salt photograph excellent in ink absorbability, recording density, water resistance and storability.
The printing speed of the latest ink jet printer is becoming higher for economic reasons. Therefore, recording sheets suitable for these printers need to absorb ink very quickly. Particularly suitable are recording sheets comprising nanocrystals, nanoporous inorganic compounds, preferably oxides such as aluminum oxide or silica, or oxide / hydroxides such as oxide / aluminum hydroxide. Is mentioned. Such a recording sheet is called a “nanoporous” recording sheet.

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

JP-A-8-034160 (Patent Document 1) describes a method for preparing a medium coated with a solution containing a silane coupling agent having a quaternary ammonium salt. The disadvantage of the method described there is that the solution containing the silane has to be applied onto the medium via a second step. Japanese Patent Application Laid-Open No. 2000-233572 (Patent Document 2) describes an ink receiving layer containing a vapor phase silica and a silane coupling agent on a water-resistant substrate. The described silanes carry alkoxy or halide groups. Japanese Patent Laid-Open No. 62-178384 (Patent Document 3) describes a method for preparing a dispersion containing silica surface-treated with a silane coupling agent. The silane coupling agent carries an epoxy, glycidoxy, amino, mercapto or methacryl functional group. WO 01 / 05,599 (Patent Document 4) describes the use of a silicon dioxide pigment in an ink jet recording sheet, wherein the surface of silicon dioxide is coated with a cationic aminoorganosiloxane. It was denatured by processing. EP 1344654 (Patent Document 5) describes a method for preparing a medium coated with a dispersion containing silica surface-modified with organosilane. EP 0983867 (Patent Document 6) describes a method for preparing an ink jet recording medium by surface treatment of colloidal silica using aminosilane. US Patent Application Publication No. 2005/0147770 (Patent Document 7) describes a method for preparing a medium sheet obtained by dispersing inorganic porous fine particles and an active ligand-containing organosilane in water. . The silanes described carry, for example, UV absorbers, sterically hindered amines, or other functional groups as substituents. In the examples there is a description of the use of silanes bearing amino groups.
All the cited patents have the disadvantage that large amounts of acid must be used to maintain the pH in the slightly acidic or neutral range desired. Large amounts of salt remaining in the media adversely affect image performance.

  Furthermore, 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 Addition of zirconium-based active inorganic polymer Etc., a method of adding various additives have been proposed.

  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. Examples of the cationic polymer include a primary amine type polymer having a structural unit derived from a primary amine such as a monoallylamine salt, and a secondary amine type polymer having a structural unit derived from a secondary amine such as a diallylamine salt. Quaternary ammonium type polymers having structural units derived from quaternary ammonium compounds such as diallyldimethylammonium chloride, primary amine type / secondary amine type copolymers having structural units derived from monoallylamine salts and diallylamine salts Etc. have been proposed (for example, Patent Documents 8 to 10).

  Furthermore, as an inkjet paper excellent in gloss, ink absorbability, light resistance, and water resistance, for example, in Patent Document 11, gas phase method silica and diallylamine derivatives such as diallyldimethylammonium chloride are provided on a water resistant support. An ink jet recording sheet provided with an ink receiving layer containing a quaternary ammonium type cationic polymer as a structural unit is described.

JP-A-8-034160 JP 2000-233572 A JP-A-62-178384 International Publication No. 01 / 05,599 Pamphlet European Patent Application No. 1344654 European Patent No. 0983867 US Patent Application Publication No. 2005/0147770 JP 60-83882 A JP-A-61-61887 JP-A-62-238783 JP 2000-2111235 A

However, for example, full-color inkjet recording images formed using the inkjet recording sheets described in Patent Documents 1 to 11 have high printing density and excellent color developability, or long-term storage stability and water resistance of images. Although it is excellent in light resistance, the glossiness of ink jet recording sheets, ink absorbability, image quality, long-term storage stability—especially insufficient storage stability (heat resistance and humidity resistance) in a high temperature and high humidity environment .
In addition, the full-color ink jet recording image formed using the ink jet recording sheet described in Patent Document 11 has problems in storage stability such as heat and humidity resistance, light resistance, and ozone resistance, as in Patent Document 1. Absorbability was also insufficient.

  An object of the present invention is to provide an ink jet recording sheet excellent in glossiness, ink absorbability, image quality, long-term storage, particularly image storage under high temperature and high humidity (hereinafter also referred to as heat and humidity resistance). And

As a result of intensive studies, the inventors have used inorganic fine particles having an average primary particle size of 30 nm or less as the inorganic fine particles to be contained in the ink receiving layer, so that glossiness, ink absorptivity, print density, image quality, etc. Has been found to improve further.
Specifically, inorganic fine particles having an average primary particle diameter of 30 nm or less, which is surface-modified with at least one aminoorganosilane, and inorganic fine particles having an average primary particle diameter of 30 nm or less, which are surface-modified with at least one cationic polymer. It was found that these problems can be solved by using in combination, and the present invention has been achieved.

〔式中、Ｘは酸残基を表す。〕

〔式中、Ｒ¹は炭素数１〜１８のアルキル基、炭素数１〜１８のアルコキシル基、炭素数６〜１２のアリール基、またはベンジル基のいずれかを表す。〕

〔式中、Ｒ²〜Ｒ⁹はそれぞれ独立に水素原子または炭素数１〜４のアルキル基を表し、Ｙ、Ｚはそれぞれ独立の酸残基を表す。〕
〔５〕表面変性無機微粒子Ａと表面変性無機微粒子Ｂの割合が、９９：１〜１：９９である〔１〕〜〔４〕のいずれかに記載のインクジェット記録用シート。 The first invention includes the following aspects.
[1] In an inkjet recording sheet having an inorganic fine particle and at least one ink receiving layer containing a binder on a support, the inorganic fine particle has an average primary particle diameter of 30 nm or less and an aminoorganosilane It comprises surface-modified inorganic fine particles A that have been surface-modified by at least one kind, and surface-modified inorganic fine particles B that have an average primary particle diameter of 30 nm or less and that have been surface-modified by at least one kind of cationic polymer. Inkjet recording sheet.
[2] Aminoorganosilane is 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyl-trimethoxysilane, (3-triethoxysilylpropyl) -diethylenetriamine, 3-aminopropyl- Triethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, (3-trimethoxy-silylpropyl) -diethylenetriamine, N- (n-butyl) -3-aminopropyltrimethoxysilane and their The inkjet recording sheet according to [1], which is at least one selected from the group consisting of a mixture.
[3] The inkjet according to [1] or [2], wherein the surface-modified inorganic fine particles A are surface-modified in the presence of at least one monovalent organic acid and aminoorganosilane. Recording sheet.
[4] The cationic polymer is at least one structural unit (b1) represented by the following general formula (1) or general formula (2), and at least one structural unit represented by the following general formula (3) It is a polymer having at least one constituent unit selected from (b2) and at least one constituent unit (b3) represented by the following general formulas (4) to (7) [1] to [3] The inkjet recording sheet according to any one of [3].

[Wherein, X represents an acid residue. ]

[Wherein, R ¹ represents an alkyl group having 1 to 18 carbon atoms, an alkoxyl group having 1 to 18 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a benzyl group. ]

[Wherein, R ^{2 to} R ⁹ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and Y and Z each represents an independent acid residue. ]
[5] The inkjet recording sheet according to any one of [1] to [4], wherein the ratio of the surface-modified inorganic fine particles A to the surface-modified inorganic fine particles B is 99: 1 to 1:99.

  In the ink jet recording sheet according to any one of [1] to [5], the inorganic fine particles are preferably vapor-phase-process silica. The ink receiving layer is preferably cured with a boron compound. Moreover, it is preferable that the said support body is a water-resistant support body. Further, a plurality of ink receiving layers having the surface-modified inorganic fine particles A and the surface-modified inorganic fine particles B can be formed. In this case, it is preferable to form by simultaneous multilayer coating.

  In addition, as a result of studies on the case where a plurality of ink-receiving layers are formed, the present inventors have found that the average primary particle diameter of which the surface is modified with at least one cationic polymer in a layer close to the support is 30 nm or less. Using inorganic fine particles whose surface is modified with at least one aminoorganosilane in the layer far from the support and having an average primary particle size of 30 nm or less improves blurring after heat and humidity treatment, and ink absorbency As a result, the present inventors have found that the recording density during recording is improved, and have reached the second invention.

〔式中、Ｘは酸残基を表す。〕

〔式中、Ｒ¹は炭素数１〜１８のアルキル基、炭素数１〜１８のアルコキシル基、炭素数６〜１２のアリール基、またはベンジル基のいずれかを表す。〕

〔式中、Ｒ²〜Ｒ⁹はそれぞれ独立に水素原子または炭素数１〜４のアルキル基を表し、Ｙ、Ｚはそれぞれ独立の酸残基を表す。〕
〔１０〕インク受容層下層とインク受容層上層の塗工量の比が、１：９９〜９９：１であることを特徴とする、〔６〕〜〔９〕のいずれかに記載のインクジェット記録用シート。 The second invention includes the following aspects.
[6] In an inkjet recording sheet having at least two ink receiving layers containing inorganic fine particles and a binder on the support, the inorganic fine particles in the lower layer of the ink receiving layer close to the support have an average primary particle size of 30 nm or less. The surface-modified inorganic fine particles B are surface-modified with at least one cationic polymer, the inorganic fine particles in the upper layer of the ink receiving layer far from the support have an average primary particle size of 30 nm or less, and aminoorganosilane An ink jet recording sheet, wherein the surface-modified inorganic fine particles A are surface-modified with at least one of the above.
[7] Aminoorganosilane is 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyl-trimethoxysilane, (3-triethoxysilylpropyl) -diethylenetriamine, 3-aminopropyl- Triethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, (3-trimethoxy-silylpropyl) -diethylenetriamine, N- (n-butyl) -3-aminopropyltrimethoxysilane and their The inkjet recording sheet according to [6], which is at least one selected from the group consisting of a mixture.
[8] The inkjet according to [6] or [7], wherein the surface-modified inorganic fine particles A are surface-modified in the presence of at least one monovalent organic acid and aminoorganosilane. Recording sheet.
[9] The cationic polymer is at least one structural unit (b1) represented by the following general formula (1) or general formula (2), and at least one structural unit represented by the following general formula (3). It is a polymer having at least one constituent unit selected from (b2) and at least one constituent unit (b3) represented by the following general formulas (4) to (7) [6] to [8] The ink jet recording sheet according to any one of [8].

[Wherein, X represents an acid residue. ]

[Wherein, R ¹ represents an alkyl group having 1 to 18 carbon atoms, an alkoxyl group having 1 to 18 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a benzyl group. ]

[Wherein, R ^{2 to} R ⁹ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and Y and Z each represents an independent acid residue. ]
[10] The ink jet recording according to any one of [6] to [9], wherein the ratio of the coating amount of the ink receiving layer lower layer and the ink receiving layer upper layer is 1:99 to 99: 1. Sheet.

  In the inkjet recording sheet according to any one of [6] to [10], at least the inorganic fine particles in the upper layer of the ink receiving layer are preferably vapor phase silica, and the inorganic fine particles in the lower layer of the ink receiving layer are also vapor phase methods. More preferred is silica. In addition, at least the upper layer of the ink receiving layer is preferably cured by a boron compound, and the lower layer of the ink receiving layer is more preferably cured by a boron compound. In addition, the inorganic fine particles in both the ink receiving layer upper layer and the ink receiving layer lower layer are vapor phase silica, and the primary particle size of the inorganic fine particles in the ink receiving layer upper layer is the same as or larger than the primary particle size of the ink receiving layer lower layer. Is preferably small. Moreover, it is preferable that the said support body is a water-resistant support body. Furthermore, the upper layer of the ink receiving layer and the lower layer of the ink receiving layer are particularly preferably formed by simultaneous multilayer coating.

  Furthermore, the present inventors have conducted research on the case where a plurality of ink receiving layers are formed. As a result, the average primary particle diameter of the surface modified with at least one aminoorganosilane on the layer close to the support is 30 nm or less. By using inorganic fine particles having an average primary particle size of 30 nm or less whose surface is modified with at least one cationic polymer in a layer far from the support, blemishes after heat and moisture treatment are improved, and The inventors found that no reduction in image quality density occurred and reached the third invention.

〔式中、Ｘは酸残基を表す。〕

〔式中、Ｒ¹は炭素数１〜１８のアルキル基、炭素数１〜１８のアルコキシル基、炭素数６〜１２のアリール基、またはベンジル基のいずれかを表す。〕

〔式中、Ｒ²〜Ｒ⁹はそれぞれ独立に水素原子または炭素数１〜４のアルキル基を表し、Ｙ、Ｚはそれぞれ独立の酸残基を表す。〕
〔１５〕インク受容層下層とインク受容層上層の塗工量の比が、１：９９〜９９：１であることを特徴とする、〔１１〕〜〔１４〕のいずれかに記載のインクジェット記録用シート。 The third invention includes the following aspects.
[11] In an inkjet recording sheet having at least two ink receiving layers containing inorganic fine particles and a binder on the support, the inorganic fine particles in the lower layer of the ink receiving layer close to the support have an average primary particle size of 30 nm or less. And the surface-modified inorganic fine particles A which are surface-modified with at least one of aminoorganosilanes, the inorganic fine particles in the upper layer of the ink receiving layer far from the support have an average primary particle size of 30 nm or less, and a cationic polymer An ink jet recording sheet, wherein the surface-modified inorganic fine particles B are surface-modified with at least one of the above.
[12] Aminoorganosilane is 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyl-trimethoxysilane, (3-triethoxysilylpropyl) -diethylenetriamine, 3-aminopropyl- Triethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, (3-trimethoxy-silylpropyl) -diethylenetriamine, N- (n-butyl) -3-aminopropyltrimethoxysilane and their The inkjet recording sheet according to [11], which is at least one selected from the group consisting of a mixture.
[13] The inkjet according to [11] or [12], wherein the surface-modified inorganic fine particles A are surface-modified in the presence of at least one monovalent organic acid and aminoorganosilane. Recording sheet.
[14] The cationic polymer is at least one structural unit (b1) represented by the following general formula (1) or general formula (2), and at least one structural unit represented by the following general formula (3) It is a polymer having at least one constituent unit selected from (b2) and at least one constituent unit (b3) represented by the following general formulas (4) to (7) [11] to [13] The ink jet recording sheet according to any one of [13].

[Wherein, X represents an acid residue. ]

[Wherein, R ¹ represents an alkyl group having 1 to 18 carbon atoms, an alkoxyl group having 1 to 18 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a benzyl group. ]

[Wherein, R ^{2 to} R ⁹ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and Y and Z each represents an independent acid residue. ]
[15] The ink jet recording according to any one of [11] to [14], wherein the ratio of the coating amount of the ink receiving layer lower layer and the ink receiving layer upper layer is 1:99 to 99: 1. Sheet.

  In the ink jet recording sheet according to any one of [11] to [15], at least the inorganic fine particles in the upper layer of the ink receiving layer are preferably vapor phase silica, and the inorganic fine particles in the lower layer of the ink receiving layer are also vapor phase methods. More preferred is silica. In addition, at least the upper layer of the ink receiving layer is preferably cured by a boron compound, and the lower layer of the ink receiving layer is more preferably cured by a boron compound. In addition, the inorganic fine particles in both the ink receiving layer upper layer and the ink receiving layer lower layer are vapor phase silica, and the primary particle size of the inorganic fine particles in the ink receiving layer upper layer is the same as or larger than the primary particle size of the ink receiving layer lower layer. Is preferably small. Moreover, it is preferable that the said support body is a water-resistant support body. Furthermore, the upper layer of the ink receiving layer and the lower layer of the ink receiving layer are particularly preferably formed by simultaneous multilayer coating.

  Then, when the inorganic fine particles having an average primary particle diameter of 30 nm or less, which is surface-modified with at least one aminoorganosilane, are used for the ink receiving layer, the present inventors use a specific cationic polymer to perform heat and moisture treatment. The inventors found that the later blemishes were improved and led to the fourth invention.

〔式中、Ｘは酸残基を表す。〕

〔式中、Ｒ¹は炭素数１〜１８のアルキル基、炭素数１〜１８のアルコキシル基、炭素数６〜１２のアリール基、またはベンジル基のいずれかを表す。〕

〔式中、Ｒ²〜Ｒ⁹はそれぞれ独立に水素原子または炭素数１〜４のアルキル基を表し、Ｙ、Ｚはそれぞれ独立の酸残基を表す。〕
〔１７〕アミノオルガノシランが、３−アミノプロピルトリメトキシシラン、Ｎ−（２−アミノエチル）−３−アミノプロピル−トリメトキシシラン、（３−トリエトキシシリルプロピル）−ジエチレントリアミン、３−アミノプロピル−トリエトキシシラン、Ｎ−（２−アミノエチル）−３−アミノプロピルトリエトキシシラン、（３−トリメトキシ−シリルプロピル）−ジエチレントリアミン、Ｎ−（ｎ−ブチル）−３−アミノプロピルトリメトキシシランおよびそれらの混合物、からなる群より選ばれる少なくとも１種である〔１６〕に記載のインクジェット記録用シート。
〔１８〕アミノオルガノシランで表面変性されてなる表面変性無機微粒子Ａが、少なくとも１種の、１価の有機酸を含有することを特徴とする、〔１６〕又は〔１７〕に記載のインクジェット記録用シート。
〔１６〕又は〔１８〕に記載のインクジェット記録用シートにおいて、アミノオルガノシランで表面変性されてなる表面変性無機微粒子Ａと、カチオン性ポリマーが同一層に存在するか、異なる層に存在するインクジェット記録用シート。 The fourth invention includes the following aspects.
[16] In an inkjet recording sheet having an inorganic fine particle and at least one ink receiving layer containing a binder on a support, the inorganic fine particle has an average primary particle diameter of 30 nm or less, and an aminoorganosilane The surface-modified inorganic fine particles A that have been surface-modified by at least one kind are contained, and at least one kind of cationic polymer is contained in at least one ink receiving layer, and the cationic polymer is represented by the following general formula (1) or general formula: It is represented by at least one structural unit (b1) represented by (2), at least one structural unit (b2) represented by the following general formula (3), and the following general formulas (4) to (7). A polymer having at least one structural unit selected from the structural units (b3). Ink-jet recording sheet.

[Wherein, X represents an acid residue. ]

[Wherein, R ¹ represents an alkyl group having 1 to 18 carbon atoms, an alkoxyl group having 1 to 18 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a benzyl group. ]

[Wherein, R ^{2 to} R ⁹ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and Y and Z each represents an independent acid residue. ]
[17] Aminoorganosilane is 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyl-trimethoxysilane, (3-triethoxysilylpropyl) -diethylenetriamine, 3-aminopropyl- Triethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, (3-trimethoxy-silylpropyl) -diethylenetriamine, N- (n-butyl) -3-aminopropyltrimethoxysilane and their The ink jet recording sheet according to [16], which is at least one selected from the group consisting of a mixture.
[18] The inkjet recording according to [16] or [17], wherein the surface-modified inorganic fine particles A that are surface-modified with aminoorganosilane contain at least one monovalent organic acid. Sheet.
In the inkjet recording sheet according to [16] or [18], the surface-modified inorganic fine particles A surface-modified with aminoorganosilane and the cationic polymer are present in the same layer or in different layers. Sheet.

  According to the present invention, an ink jet recording sheet excellent in ink absorbability, print density, and long-term storage can be obtained.

  The present invention provides (1) an ink jet recording sheet having an ink receiving layer containing inorganic fine particles A surface-modified with aminoorganosilane and inorganic fine particles B surface-modified with a cationic polymer on a support, (2 ) An ink jet recording sheet having an ink receiving layer lower layer containing inorganic fine particles B surface-modified with a cationic polymer, and an ink receiving layer upper layer containing inorganic fine particles A surface-modified with aminoorganosilane on a support; (3) For ink jet recording having an ink receiving layer lower layer containing inorganic fine particles A surface-modified with aminoorganosilane and an ink receiving layer upper layer containing inorganic fine particles B surface-modified with a cationic polymer on a support. Sheet, (4) surface modified with aminoorganosilane on support Ink jet recording sheet having an ink-receiving layer having a specific cationic polymer and inorganic fine particles A, a. First, after explaining the constituent materials common to each inkjet recording sheet, each invention will be explained.

"About support"
As the support, a known ink jet recording sheet can be appropriately used. More specifically, as a support, for example, paper (acid paper, neutral paper, etc.), baryta paper, synthetic paper, nonwoven fabric, plastic film, a support in which one or both sides of paper are coated with a resin such as polyolefin ( So-called RC paper), a laminated sheet in which a nonwoven fabric or a plastic film is bonded to one side or both sides of the paper with an adhesive. Examples of the plastic film include polyolefin resins such as polyester and polypropylene, films of nylon and polyester, and synthetic paper.

  Among these, a water-resistant support in which the ink liquid does not penetrate into the support is preferable because a clear image can be obtained at a higher concentration. As the water-resistant support, a support in which both sides of the paper are coated with a polyolefin resin is preferably used because a recorded image is close to photographic quality and a high-quality image can be obtained at low cost. On the other hand, absorptive supports such as paper (acidic paper, neutral paper, etc.), coated paper, baryta paper, etc. are preferable because they have good ink absorbability and ink drying properties and are excellent in high-speed printability. In addition, although there is no restriction | limiting in particular as thickness of a support body, For example, 100-400 micrometers is preferable.

About inorganic fine particles
The ink receiving layer contains inorganic fine particles having an average primary particle diameter of 30 nm or less. By containing inorganic fine particles having an average primary particle diameter of 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 primary particle diameter of the inorganic fine particles is more preferably 3 to 15 nm. In addition, the primary particle diameter as used in the field of this invention is a particle diameter (Martin diameter) observed with the electron microscope (SEM and TEM).

  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, aluminum silicate, diatomaceous earth. Soil, calcium silicate, magnesium silicate, silica, aluminum hydroxide, alumina, alumina hydrate, aluminosilicate, boehmite, pseudoboehmite, etc. are mentioned, but especially silica, alumina, alumina hydrate in terms of ink absorbency And aluminosilicates are preferred, especially silica.

The inorganic fine particles preferably have a specific surface area of 100 m ² / g or more by the BET method. Although there is no upper limit to the specific surface area according to the BET method, it is preferably about 1000 m ² / g or less. More preferably, it is 150-400 m < ² > / g, More preferably, it is 200-400 m < ² > / g. The BET method referred to in the present invention is one of powder surface measurement methods by a gas phase adsorption method, and is a method for obtaining the total surface area, that is, the specific surface area of a 1 g sample from an adsorption isotherm.

  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 0.05 to 0.5 μm. The average secondary particle size can be adjusted by pulverization by a mechanical method such as ultrasonic waves, high-speed rotary mill, roller mill, container drive medium mill, medium agitation mill, jet mill, pulverizer, and sand grinder.

As described above, silica is preferably used as the inorganic fine particles. Silica is roughly classified into natural silica obtained by pulverizing natural silica such as quartz and synthetic silica produced by synthesis. It is roughly divided into phase method silica and wet method silica.
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. Vapor phase method silica is preferably used because high ink absorption, transparency and gloss can be obtained.

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 are formed by combining primary particles of silica to form secondary particles, and there are many voids between the primary particles and between the secondary particles. In addition to being large, the property of scattering light is small, so a high printing density can be obtained.

These wet process silicas preferably have a specific surface area by the BET method of 100 to 400 m ² / g and a pore volume of 0.5 to 2.0 ml / g. Wet method silica in this range is preferred because the ink-receiving layer has a very good balance of cracks, ink absorbency, and gloss.

  The amount of inorganic fine particles used in the ink receiving layer is preferably about 20 to 90% by weight, more preferably about 30 to 85% by weight, based on the solid content of the ink receiving layer. Within this range, there is no fear that the coating film strength of the ink receiving layer is lowered, the ink absorbability and the ink drying property are excellent, and a higher image quality is obtained.

［式中、Ｒ¹⁰、Ｒ¹¹、Ｒ¹²は独立して、水素、ヒドロキシル、１〜６個の炭素原子を有する非置換もしくは置換アルキル、非置換もしくは置換アリール、１〜６個の炭素原子を有する非置換もしくは置換アルコキシル、または非置換もしくは置換アリールオキシルを表し、そしてＲ¹³は、少なくとも１個の第一級、第二級または第三級アミノ基により置換された有機残基を表す。］
Ｒ¹⁰、Ｒ¹¹、およびＲ¹²が置換されている場合には、その置換基は独立して、チオール、スルフィドおよびポリアルキレンオキシドからなる群より選択される。好適に選択された置換基によって、シリカの表面変性が容易となり、その結果、二酸化ケイ素を含有する分散体および塗工液のレオロジー的挙動の改良が図れ、さらに、大気汚染物に対する安定性、耐光抵抗性および物理的性質など、記録用シートの性能も改良される。 About aminoorganosilane
The ink receiving layer contains aminoorganosilane. The aminoorganosilane is not particularly limited, but a suitable aminoorganosilane is an aminoorganosilane of the general formula (8).

[Wherein R ¹⁰ , R ¹¹ , R ¹² independently represent hydrogen, hydroxyl, unsubstituted or substituted alkyl having 1 to 6 carbon atoms, unsubstituted or substituted aryl, 1 to 6 carbon atoms. Represents unsubstituted or substituted alkoxyl, or unsubstituted or substituted aryloxyl, and R ¹³ represents an organic residue substituted by at least one primary, secondary or tertiary amino group. ]
When R ¹⁰ , R ¹¹ , and R ¹² are substituted, the substituents are independently selected from the group consisting of thiols, sulfides, and polyalkylene oxides. Suitably selected substituents facilitate the surface modification of the silica, resulting in improved rheological behavior of dispersions and coating fluids containing silicon dioxide, as well as stability against air pollutants, light resistance The performance of the recording sheet, such as resistance and physical properties, is also improved.

Instead of the monomeric aminoorganosilane, a condensation reaction product of aminoorganosilane may be used. The condensation reaction can occur between the same aminoorganosilanes or between different aminoorganosilanes.
Suitable aminoorganosilanes include 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, (3-triethoxysilylpropyl) -diethylenetriamine, 3-aminopropyltriethoxy. Silane, N- (2-aminoethyl) -3-amino-propyltriethoxy-silane, (3-triethoxysilylpropyl) -diethylenetriamine, N- (n-butyl) -3-aminopropyltrimethoxysilane and their Mention may be made of mixtures.

“Surface-modified inorganic fine particles A with aminoorganosiloxane”
When the inorganic fine particles are surface-modified with aminoorganosilane, it is preferable to add and use a monovalent acid in addition to aminoorganosilane and inorganic fine particles. Suitable monovalent acids include inorganic acids such as hydrochloric acid or nitric acid; organic acids such as carboxylic acid, formic acid, acetic acid, propionic acid, lactic acid, acrylic acid, glyoxylic acid, methoxyacetic acid, chloroacetic acid, dichloroacetic acid, trichloroacetic acid Alternatively, α-hydroxyisobutyric acid, sulfonic acid, methanesulfonic acid, ethanesulfonic acid and the like can be mentioned. Of these, monovalent acids are more preferably formic acid, acetic acid or propionic acid, and most preferably formic acid. In addition, the above illustrations are examples of possible acids and do not limit the use of other monovalent acids not mentioned in any aspect. It is also possible to form monovalent acid salts using various monovalent cations such as lithium, sodium, potassium, and ammonium.

As a method for preparing the surface-modified inorganic fine particles, the inorganic fine particles are mixed, for example, at a high shear rate, in a mainly aqueous solution containing at least one aminoorganosilane and at least one monovalent acid or salt thereof. It is preferable to add. Under appropriate conditions, a dispersion of surface-modified inorganic fine particles can be obtained without agglomeration.
It is preferred to use deionized water when preparing a predominantly aqueous solution. It is also possible to add water miscible solvents such as lower alcohols (methanol, ethanol, propanol etc.) or ketones such as acetone.

Further, as a method for preparing surface-modified inorganic fine particles, for example, a solution containing at least one aminoorganosilane and at least one monovalent acid or salt thereof is added to an aqueous dispersion of inorganic fine particles. Also good.
Alternatively, the inorganic fine particles can be mixed with a mixture of at least one aminoorganosilane and water under high shear, and a monovalent acid can be continuously added to balance the pH. is there.
In addition, inorganic fine particles are added to a solution of monovalent organic acid and water, thereby producing an anionic dispersion of inorganic fine particles at low pH, and at least one aminoorganosilane is added under high shear Thus, the net charge on the surface of the inorganic fine particles can be reversed.

  In the present invention, the surface-modified inorganic fine particles are prepared by preparing an aqueous solution of at least one aminoorganosilane; adding at least one monovalent acid or salt to the aqueous solution, Carrying out a method comprising a step of forming a solution containing the monovalent acid or a salt thereof; and a step of modifying the surface of the inorganic fine particles by adding inorganic fine particles to the solution thus formed. Is preferred.

For example, when the inorganic fine particles are silica, it is preferable to hydrolyze the aminoorganosilane in water at room temperature, then add a monovalent acid, and further stir the mixture at room temperature. In this way, the aminoorganosilane is rapidly hydrolyzed at a high pH, and the reaction product of the monovalent acid and aminoorganosilane is formed by adding the monovalent acid. Finally, silica powder is added little by little to the solution containing the reaction product of the monovalent acid and aminoorganosilane.
Modifying the surface of silica with a solution containing an aminoorganosilane and a monovalent acid or salt thereof is an almost instantaneous process. For this reason, the conversion time is very short and is preferred because it is completed at room temperature.

  In addition, as the inorganic fine particles for surface modification, silica is preferable, and vapor phase method silica is particularly preferable. Instead of a single vapor phase silica powder, it is also possible to use a mixture of different silica powders having different primary particle sizes. The modification step using a solution containing an aminoorganosilane and a monovalent acid or salt thereof can be carried out independently for each silica powder, or simultaneously for a mixture of different silica powders. You may implement. If the modification step is carried out at a high shear rate, the reaction product is regularly distributed on the surface of the silica. Moreover, the rheological behavior of the dispersion is also improved.

The dispersion of the surface-modified inorganic fine particles A with aminoorganosilane is advantageously used directly for preparing a coating liquid for the ink receiving layer of the ink jet recording sheet. Therefore, the dispersion is stable for at least 24 hours, the surface-modified inorganic fine particles must not settle, and the viscosity is not allowed to change to any significant extent. Specifically, gelation or aggregation should not occur.
The dispersion contains the surface-modified inorganic fine particles A according to the present invention in an amount of 5% by mass to 50% by mass. An amount of 10% by mass to 30% by mass is preferable, and an amount of 15% by mass to 25% by mass is particularly preferable.

About cationic polymers
The cationic polymer used in the present invention is not particularly limited, and known cationic polymers can be used as mordants for inkjet recording. For example, a primary amine type cationic polymer having a primary amine salt as a constituent unit, such as monoallylamine salt, vinylamine salt, N-vinylacrylamidine salt, dicyandiamide / formalin polycondensate, dicyandiamide / polyethyleneamine polycondensate, diallylamine Salt, secondary amine type cationic polymer having a secondary amine salt such as ethyleneimine salt as a structural unit, tertiary amine type cationic polymer having a tertiary amine salt such as diallylmethylamine salt as a structural unit, diallyldimethylammonium Constituent units of quaternary ammonium salts such as chloride, (meth) acryloyloxyethyltrimethylammonium chloride, (meth) acrylamidopropyltrimethylammonium chloride, dimethylamine / epichlorohydrin polycondensate Quaternary ammonium type cationic polymer and having it, and the like.

  Among them, at least one structural unit (b1) represented by the following general formula (1) or general formula (2), at least one structural unit (b2) represented by the following general formula (3), and The polymer having at least one structural unit selected from the structural units (b3) represented by the general formulas (4) to (7) is an inorganic fine particle whose surface is modified with the aminoorganosilane. Use in combination with A is preferable because it improves the printing density, ink absorbency and heat and humidity resistance in a well-balanced manner.

〔式中、Ｘは酸残基を表す。〕
一般式（２）中、ＨＸで表される酸は、無機酸、有機酸のいずれでもよく、無機酸としては、塩酸、硫酸、硝酸、リン酸、ピロリン酸、メタリン酸等が挙げられ、有機酸としては、ギ酸、酢酸、プロピオン酸、メタンスルホン酸、ｐ−トルエンスルホン酸等が挙げられる。これらは、それぞれ単独で又は２種以上を併用することができる。これらの酸のうちでも、塩酸、硫酸は特に画像保存性に効果的であり好ましい。 (Structural unit (b1))

[Wherein, X represents an acid residue. ]
In the general formula (2), the acid represented by HX may be either 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. Examples of the acid include 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 acids, hydrochloric acid and sulfuric acid are particularly preferable because they are effective for image storability.

〔式中、Ｒ¹は炭素数１〜１８のアルキル基、炭素数１〜１８のアルコキシル基、炭素数６〜１２のアリール基、またはベンジル基のいずれかを表す。〕
一般式（３）の炭素数１〜１８のアルキル基の具体例としては、メチル、エチル、ｎ−プロピル、ｉ−プロピル、ブチル、ペンチル、ヘキシル、オクチル、ノニル、デシル、ドデシル、オクタデシル等が挙げられる。炭素数１〜１８のアルコキシル基の具体例としては、メトキシ、エトキシ、プロポキシ、ブトキシ、ペンタオキシ、ヘキサオキシ、オクチルオキシ、ノニルオキシ、デシルオキシ、ドデシルオキシ、オクタデシルオキシ等が挙げられる。さらに、炭素数６〜１２のアリール基の具体例としては、フェニル基、トリル基、メトキシフェニル基、ナフチル基等が挙げられる。これらのうちでも、メトキシ基は製造が容易であり、とりわけ耐熱湿性に優れているため好ましい。 (Structural unit (b2))

[Wherein, R ¹ represents an alkyl group having 1 to 18 carbon atoms, an alkoxyl group having 1 to 18 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a benzyl group. ]
Specific examples of the alkyl group having 1 to 18 carbon atoms of the general formula (3) include methyl, ethyl, n-propyl, i-propyl, butyl, pentyl, hexyl, octyl, nonyl, decyl, dodecyl, octadecyl and the like. It is done. Specific examples of the alkoxyl group having 1 to 18 carbon atoms include methoxy, ethoxy, propoxy, butoxy, pentaoxy, hexaoxy, octyloxy, nonyloxy, decyloxy, dodecyloxy, octadecyloxy and the like. Furthermore, specific examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a tolyl group, a methoxyphenyl group, and a naphthyl group. Among these, a methoxy group is preferable because it is easy to produce and is particularly excellent in heat and humidity resistance.

〔式中、Ｒ²〜Ｒ⁹はそれぞれ独立に水素原子または炭素数１〜４のアルキル基を表し、Ｙ、Ｚはそれぞれ独立の酸残基を表す。〕
一般式（６）、（７）中、ＨＹ、ＨＺで表される酸は、無機酸、有機酸のいずれでもよく、無機酸としては、塩酸、硫酸、硝酸、リン酸、ピロリン酸、メタリン酸等が挙げられ、有機酸としては、ギ酸、酢酸、プロピオン酸、メタンスルホン酸、ｐ−トルエンスルホン酸等が挙げられる。これらは、それぞれ単独で又は２種以上を併用することができる。これらの酸のうちでも、塩酸、硫酸は特に画像保存性に効果的であり好ましい。
一般式（４）〜（７）中、Ｒ²〜Ｒ⁹が全て水素原子であるカチオン性ポリマーは、インク吸収性に優れた高画質の画像が得られるため、特に好ましい。
具体例としては、一般式（４）、（５）、（６）、（７）で表されるジアリルアミン、ジ（２−メチルアリル）アミン、ジ（２−エチルアリル）アミン等の、２個のビニルアルキル基を有する２級アミンまたはその酸塩をモノマーとする構成単位が挙げられる。とりわけ、構成単位（ｂ３）がジアリルアミンまたはその酸塩をモノマーとする構成単位であるカチオン性ポリマーは、高画質が得られ、耐光性、耐オゾン性等の保存性にも優れているため好ましい。 (Structural unit (b3))

[Wherein, R ^{2 to} R ⁹ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and Y and Z each represents an independent acid residue. ]
In general formulas (6) and (7), the acid represented by HY and HZ 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, and metaphosphoric acid. Examples of the organic acid include 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 acids, hydrochloric acid and sulfuric acid are particularly preferable because they are effective for image storability.
In general formulas (4) to (7), a cationic polymer in which R ^{2 to} R ⁹ are all hydrogen atoms is particularly preferable because a high-quality image excellent in ink absorbability can be obtained.
Specific examples include two vinyls such as diallylamine, di (2-methylallyl) amine, and di (2-ethylallyl) amine represented by general formulas (4), (5), (6), and (7). Examples thereof include a structural unit having a secondary amine having an alkyl group or an acid salt thereof as a monomer. In particular, a cationic polymer in which the structural unit (b3) is a structural unit having diallylamine or an acid salt thereof as a monomer is preferable because high image quality is obtained and storage stability such as light resistance and ozone resistance is excellent.

  As the cationic polymer, at least one structural unit (b1) represented by general formula (1) or general formula (2), at least one structural unit (b2) represented by general formula (3), And a polymer having at least one structural unit selected from the structural units (b3) represented by the general formulas (4) to (7) is preferable. The polymer having is more preferable.

  For example, a cationic polymer having the structural unit (b1) and the structural unit (b2) has good coating stability, and in particular, an image with high image quality and excellent long-term storage stability can be obtained. The molar ratio of the structural unit (b1) to the structural unit (b2) is preferably 0.1: 1 to 50: 1, more preferably 0.5: 1 to 20: 1. Furthermore, the polymer having the structural units (b1), (b2), and (b3) is further excellent in storage stability such as light resistance and ozone resistance. In this case, the molar ratio of the total of the structural unit (b1) and the structural unit (b2) to the structural unit (b3) in the polymer is preferably 0.1: 1 to 10: 1, more preferably 0.5: 1. ~ 5: 1.

  The molecular weight of the cationic polymer used in the present invention is preferably 1,000 to 500,000, more preferably 5,000 to 200,000. Within this range, coating stability is good, high image quality can be obtained, storage stability such as light resistance and heat and humidity resistance, and ink absorption are excellent, and cracks are also improved.

The content of the cationic polymer in the ink receiving layer is preferably 0.01 to 10 g / m ² , more preferably 0.05 to 5 g / m ² . When used in this range, the image quality, image storability and ink absorption are excellent.
The method for including the cationic polymer in the ink receiving layer is not particularly limited, but it may be added to the ink receiving layer coating solution for coating, before or at the same time as the ink receiving layer coating, or the ink receiving layer. After coating, there is a method of coating an aqueous solution containing a cationic polymer.
Further, when the cationic polymer is once used after being changed to the surface-modified inorganic fine particles B by the cationic polymer, the resulting ink receiving layer has transparency, ink absorbability, ink color development, weather resistance, and the like. Since it becomes a favorable porous layer, it is preferable.

“Surface-modified inorganic fine particles B with cationic polymer”
Surface-modified inorganic fine particles B with a cationic polymer are obtained by pulverizing and dispersing inorganic fine particles-cationic polymer aggregate particles obtained by mixing and aggregating inorganic fine particles with a cationic polymer to an average particle diameter of 700 nm or less. can get.
For example, it can be obtained by applying a strong force by mechanical means to a mixture of inorganic particles such as silica and a cationic polymer. That is, it can be obtained by a breaking down method (a method of subdividing a bulk material). The surface-modified inorganic fine particles B by the cationic polymer may be a slurry. The mechanical means include ultrasonic, high-speed rotary mill, roller mill, container drive medium mill, medium agitation mill, jet mill, crusher, sand grinder, etc., commercially available dispersion equipment, manufactured by Yoshida Machine Industry Co., Ltd. The dispersion can be carried out using a dispersion means such as Nanomizer, Sugino Machine Optimizer, APV Manton-Gorin, Istral Conti-TDS, or the like. A plurality of these means may be combined as appropriate.

The average particle diameter referred to in the present invention is a particle diameter observed with an electron microscope (SEM and TEM) (taken an electron micrograph of 10,000 to 400,000 times, and measured and averaged the diameter of the particles in a 5 cm square. (It is described in "Particle Handbook", Asakura Shoten, p52, 1991, etc.).
The average particle diameter (substantially secondary particles) of the surface-modified inorganic fine particles B is 700 nm or less, preferably 10 to 500 nm, more preferably 20 to 300 nm. If the surface-modified inorganic fine particles B having an average particle diameter exceeding 700 nm are used, the transparency is remarkably lost, the printing density is remarkably lowered, and there is a possibility that an ink jet recording sheet having high gloss after printing cannot be obtained. On the other hand, if silica colloidal particles having an extremely small average particle diameter are used, there is a possibility that a sufficient ink absorption rate cannot be obtained.

As the inorganic fine particles constituting the surface-modified inorganic fine particles B by the cationic polymer, silica is preferable, and vapor phase method silica is particularly preferable. The surface-modified inorganic fine particles B using silica are particularly excellent in ink absorbability and can form a transparent ink receiving layer.
The amorphous silica constituting the silica-cationic compound aggregate fine particles constituting the surface-modified inorganic fine particles B preferably has an average primary particle diameter of 3 nm 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 aggregated secondary particles become large, and the transparency of the ink receiving layer may be lowered. The surface-receptive inorganic fine particles A and B, a binder, a cross-linking agent and the like are appropriately combined to form an ink-receiving layer coating solution.

"About the binder"
Examples of the binder to be blended in the ink receiving layer include starch derivatives such as oxidized starch and etherified starch, cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, α-, β-, γ-cyclodextrin, casein, gelatin, albumin, Gum arabic, sodium or potassium alginate, proteins such as soybean protein, polyvinyl alcohols such as polyvinyl alcohol, silicon-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, cation-modified polyvinyl alcohol, styrene-maleic anhydride copolymer salt , Water-based adhesives such as styrene-butadiene latex, acrylic latex, polyester polyurethane latex, vinyl acetate latex, or polymethyl methacrylate Over DOO, polyurethane resins, unsaturated polyester resins, vinyl chloride - vinyl acetate copolymer, polyvinyl butyral, and an 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, there is an advantage that the ink does not swell at the initial permeation of the ink so as to block the gap.

  Among the polyvinyl alcohols, polyvinyl alcohol, cation-modified polyvinyl alcohol or silicon-modified polyvinyl alcohol is particularly preferably used.

  As the 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, and an average polymerization degree thereof is preferably 200 to 5,000, 5,000 is 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. If the amount of the binder added is large, the pores between the particles may be small, and a sufficient ink absorption rate may not be obtained, while if the binder is small, the coating layer will crack and become unusable. Sometimes it becomes.

“Crosslinking agent”
It is more preferable to use a crosslinking agent in the ink receiving layer coating liquid from the viewpoint of suppressing cracks. Specific examples of the crosslinking agent include, for example, boron compounds such as boric acid, borax, borate, glyoxal, melamine / formaldehyde, glutaraldehyde, methylol urea, dioxane, reactive vinyl compound, polyisocyanate compound, epoxy compound, Examples include an aziridine compound, a carbodiimide compound, a dihydrazide compound, an aluminum compound, and a zirconium compound. Among these, a boron compound is preferable, and boric acid is particularly preferable because it can increase the light resistance of an image.
The coating amount of the crosslinking agent, preferably ^{0.005~3.0g / m 2, 0.01~2.0g / m} 2 is more preferable. If it is less than 0.005 g / m ^2, cracks preventing effect is low, if it exceeds 3.0 g / m ^2, or cause cracks folded by a strong contraction of the dry ink receiving layer, ink absorption is reduced risk There is.

"Other materials in the ink receiving layer"
In the present invention, in order to further improve the heat and humidity resistance, the ink receiving layer contains an aluminum compound such as basic aluminum chloride, basic aluminum sulfate, basic aluminum lactate and basic fatty acid aluminum, or zirconyl chloride or basic zirconyl chloride. Zirconium compounds such as zirconyl nitrate and fatty acid zirconyl can also be contained. When added, it may be in the ink-receiving layer coating solution or when dispersed in silica, but it is particularly preferred to add during dispersion of silica.
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, among which acetic acid is particularly preferable.

  In the present invention, various known compounds used for the purpose of improving storage stability such as light resistance and gas resistance, such as phenolic antioxidants, hindered amine light stabilizers, benzotriazole ultraviolet absorbers, sulfur compounds It is also possible to use water-soluble metal salts and the like.

  In the present invention, it is also possible to use phosphorus oxoacid salts as paint stabilizers. 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. Among these, hypophosphite is preferably used because it has a particularly high effect on 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. Among these, sodium hypophosphite is particularly preferably used because it has the highest effect on paint stability.

  In the ink receiving layer, various known pigment dispersants, thickeners, fluidity modifiers, antifoaming agents, antifoaming agents, mold release agents, foaming agents, penetrating agents, coloring dyes, coloring pigments, fluorescence Brightening agents, preservatives, antifungal agents and the like can be added as appropriate.

The ink receiving layer is formed by applying and drying the ink receiving layer coating liquid containing the various components described above on at least one surface of the support. The coating amount of the ink receiving layer coating liquid is preferably ² to 50 g / m ² , more preferably ³ to 30 g / m ² in terms of dry mass. When the coating amount is within this range, the recording image quality and the coating film strength are excellent.
The ink receiving layer coating liquid can be applied by a coating method such as a bar coater, a blade coater, an air knife coater, a gravure coater, a die coater, a curtain coater, or a slide bead coater.

"About the first invention"
The first invention is an ink jet recording having an ink receiving layer containing inorganic fine particles A surface-modified with the aminoorganosilane, inorganic fine particles B surface-modified with the cationic polymer, and the binder on the support. Sheet.

That is, in the inkjet recording sheet having at least one ink receiving layer containing inorganic fine particles and a binder on the support, the inorganic fine particles have an average primary particle diameter of 30 nm or less, and at least aminoorganosilane. Inkjet comprising surface-modified inorganic fine particles A surface-modified by one kind and surface-modified inorganic fine particles B having an average primary particle diameter of 30 nm or less and surface-modified by at least one kind of cationic polymer This is a recording sheet.
By forming an ink receiving layer that uses the surface-modified surface-modified inorganic fine particles A and the surface-modified surface-modified inorganic fine particles B in combination, an ink jet recording sheet excellent in print density, ink absorbability, and heat and humidity resistance can be obtained. .

  The aminoorganosilane that forms the surface-modified inorganic fine particles A is 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyl-trimethoxysilane, (3-triethoxysilylpropyl) -diethylenetriamine, 3-aminopropyl-triethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, (3-trimethoxy-silylpropyl) -diethylenetriamine, N- (n-butyl) -3-aminopropyltri At least one selected from the group consisting of methoxysilane and a mixture thereof is particularly preferable because printing density, ink absorbability, and heat and humidity resistance are excellent. Further, it is preferable that the surface-modified inorganic fine particles A contain at least one kind of monovalent organic acid since the printing storability such as water resistance is improved.

  On the other hand, the cationic polymer forming the surface-modified inorganic fine particles B is represented by at least one structural unit (b1) represented by the general formula (1) or the general formula (2) and the general formula (3). At least one structural unit selected from the structural units (b2) and at least one structural unit (b3) represented by the general formulas (4) to (7). A polymer is preferable because the blur after the heat and humidity treatment is improved, and having at least two structural units is more preferable because the blur after the heat and humidity treatment and the print density are improved.

The ratio of the surface-modified inorganic fine particles A and the surface-modified inorganic fine particles B is preferably 99: 1 to 1:99, and more preferably 95: 5 to 20:80.
Further, it is preferable that at least one of the surface-modified inorganic fine particles A and the surface-modified inorganic fine particles B, and preferably both inorganic fine particles are vapor phase method silica. The ink receiving layer is preferably cured by a crosslinking agent such as a boron compound. Moreover, it is preferable that the said support body is a water-resistant support body. Further, a plurality of ink receiving layers having the surface-modified inorganic fine particles A and the surface-modified inorganic fine particles B can be formed. In this case, it is preferable to form by simultaneous multilayer coating.

"About the second invention"
The second invention is an ink receiving layer lower layer containing inorganic fine particles B surface-modified with the cationic polymer and the binder on the support, inorganic fine particles A surface-modified with the aminoorganosilane, and the binder. An ink receiving layer containing an ink receiving layer.

That is, in the inkjet recording sheet having at least two ink receiving layers containing inorganic fine particles and a binder on the support, the inorganic fine particles in the lower layer of the ink receiving layer close to the support have an average primary particle size of 30 nm or less. The surface-modified inorganic fine particles B are surface-modified with at least one cationic polymer, the inorganic fine particles in the upper layer of the ink receiving layer far from the support have an average primary particle size of 30 nm or less, and the aminoorganosilane An ink jet recording sheet characterized in that the surface-modified inorganic fine particles A are surface-modified with at least one kind.
By adopting a laminated structure of an ink-receiving layer lower layer having surface-modified surface-modified inorganic fine particles B and an ink-receiving layer upper layer having surface-modified surface-modified inorganic fine particles A, the print density, ink absorbability, and heat and humidity resistance are improved. An excellent ink jet recording sheet can be obtained.

  The aminoorganosilane that forms the surface-modified inorganic fine particles A is 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyl-trimethoxysilane, (3-triethoxysilylpropyl) -diethylenetriamine, 3-aminopropyl-triethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, (3-trimethoxy-silylpropyl) -diethylenetriamine, N- (n-butyl) -3-aminopropyltri At least one selected from the group consisting of methoxysilane and a mixture thereof is particularly preferable because printing density, ink absorbability, and heat and humidity resistance are excellent. Further, it is preferable that the surface-modified inorganic fine particles A contain at least one kind of monovalent organic acid because printing storability such as water resistance is improved.

  On the other hand, the cationic polymer forming the surface-modified inorganic fine particles B is represented by at least one structural unit (b1) represented by the general formula (1) or the general formula (2) and the general formula (3). At least one structural unit selected from the structural units (b2) and at least one structural unit (b3) represented by the general formulas (4) to (7). A polymer is preferable because bleeding after the heat and humidity treatment is improved, and having at least two structural units is more preferable because the bleeding after the heat and humidity treatment and the print density during recording are improved.

  The ratio of the coating amount of the ink receiving layer lower layer and the ink receiving layer upper layer is 1:99 to 99: 1, preferably 5:95 to 70:30, more preferably 10:90 to 50:50, This is preferable because of excellent ink absorbability.

  In addition, at least the inorganic fine particles in the upper layer of the ink receiving layer are preferably vapor phase silica, and the inorganic fine particles in the lower layer of the ink receiving layer are more preferably vapor phase silica. In addition, at least the upper layer of the ink receiving layer is preferably cured by a boron compound, and the lower layer of the ink receiving layer is more preferably cured by a boron compound. In addition, the inorganic fine particles in both the ink receiving layer upper layer and the ink receiving layer lower layer are vapor phase silica, and the primary particle size of the inorganic fine particles in the ink receiving layer upper layer is the same as or larger than the primary particle size of the ink receiving layer lower layer. Is preferably small. Moreover, it is preferable that the said support body is a water-resistant support body. Furthermore, the upper layer of the ink receiving layer and the lower layer of the ink receiving layer are particularly preferably formed by simultaneous multilayer coating.

"About the third invention"
According to a third aspect of the present invention, there is provided an ink receiving layer lower layer containing the inorganic fine particles A surface-modified with the aminoorganosilane and the binder on the support, the inorganic fine particles B surface-modified with the cationic polymer, and the binder. An ink receiving layer containing an ink receiving layer.

That is, in the inkjet recording sheet having at least two ink receiving layers containing inorganic fine particles and a binder on the support, the inorganic fine particles in the lower layer of the ink receiving layer close to the support have an average primary particle size of 30 nm or less. A surface-modified inorganic fine particle A that has been surface-modified with at least one aminoorganosilane, the inorganic fine particles in the upper layer of the ink receiving layer far from the support have an average primary particle size of 30 nm or less, and a cationic polymer An ink jet recording sheet, wherein the surface modified inorganic fine particles B are surface-modified with at least one kind.
By adopting a laminated structure of an ink-receiving layer lower layer having surface-modified surface-modified inorganic fine particles A and an ink-receiving layer upper layer having surface-modified surface-modified inorganic fine particles B, print density, ink absorbability, heat and humidity resistance, An ink jet recording sheet having an excellent image density after heat and humidity treatment can be obtained.

  The aminoorganosilane that forms the surface-modified inorganic fine particles A is 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyl-trimethoxysilane, (3-triethoxysilylpropyl) -diethylenetriamine, 3-aminopropyl-triethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, (3-trimethoxy-silylpropyl) -diethylenetriamine, N- (n-butyl) -3-aminopropyltri At least one selected from the group consisting of methoxysilane and a mixture thereof is particularly preferable because printing density, ink absorbability, and heat and humidity resistance are excellent. Further, it is preferable that the surface-modified inorganic fine particles A contain at least one kind of monovalent organic acid since the printing storability such as water resistance is improved.

  On the other hand, the cationic polymer forming the surface-modified inorganic fine particles B is represented by at least one structural unit (b1) represented by the general formula (1) or the general formula (2) and the general formula (3). At least one structural unit selected from the structural units (b2) and at least one structural unit (b3) represented by the general formulas (4) to (7). A polymer is preferable because the blur after the heat and humidity treatment is improved, and having at least two structural units is more preferable because the blur after the heat and humidity treatment and the print density after recording are improved.

  The ratio of the coating amount of the ink receiving layer lower layer and the ink receiving layer upper layer is 1:99 to 99: 1, preferably 30:70 to 95: 5, more preferably 50:50 to 90:10, This is preferable because of excellent ink absorbability.

  In addition, at least the inorganic fine particles in the upper layer of the ink receiving layer are preferably vapor phase silica, and the inorganic fine particles in the lower layer of the ink receiving layer are more preferably vapor phase silica. In addition, at least the upper layer of the ink receiving layer is preferably cured by a boron compound, and the lower layer of the ink receiving layer is more preferably cured by a boron compound. In addition, the inorganic fine particles in both the ink receiving layer upper layer and the ink receiving layer lower layer are vapor phase silica, and the primary particle size of the inorganic fine particles in the ink receiving layer upper layer is the same as or larger than the primary particle size of the ink receiving layer lower layer. Is preferably small. Moreover, it is preferable that the said support body is a water-resistant support body. Furthermore, the upper layer of the ink receiving layer and the lower layer of the ink receiving layer are particularly preferably formed by simultaneous multilayer coating.

〔式中、Ｘは酸残基を表す。〕

〔式中、Ｒ¹は炭素数１〜１８のアルキル基、炭素数１〜１８のアルコキシル基、炭素数６〜１２のアリール基、またはベンジル基のいずれかを表す。〕

〔式中、Ｒ²〜Ｒ⁹はそれぞれ独立に水素原子または炭素数１〜４のアルキル基を表し、Ｙ、Ｚはそれぞれ独立の酸残基を表す。〕 "About the fourth invention"
The fourth invention is an ink jet recording sheet having an ink receiving layer having inorganic fine particles A surface-modified with the aminoorganosilane, the specific cationic polymer, and a binder on the support.
That is, in the inkjet recording sheet having at least one ink receiving layer containing inorganic fine particles and a binder on the support, the inorganic fine particles have an average primary particle diameter of 30 nm or less, and at least aminoorganosilane. The surface-modified inorganic fine particles A that have been surface-modified by one kind, at least one kind of cationic polymer in at least one ink receiving layer, and the cationic polymer represented by the following general formula (1) or general formula ( 2) At least one structural unit (b1) represented by the formula (3), at least one structural unit (b2) represented by the following general formula (3), and the following general formulas (4) to (7) A polymer having at least one structural unit selected from the structural units (b3). It is an ink jet recording sheet.

[Wherein, X represents an acid residue. ]

[Wherein, R ¹ represents an alkyl group having 1 to 18 carbon atoms, an alkoxyl group having 1 to 18 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a benzyl group. ]

[Wherein, R ^{2 to} R ⁹ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and Y and Z each represents an independent acid residue. ]

  By using in combination the surface-modified inorganic fine particles A surface-modified with at least one aminoorganosilane and the above-mentioned specific cationic polymer, an ink jet recording sheet having excellent printing density, ink absorbability, and heat and humidity resistance can be obtained. .

The aminoorganosilane constituting the surface-modified inorganic fine particles A is 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyl-trimethoxysilane, (3-triethoxysilylpropyl) -diethylenetriamine, 3-aminopropyl-triethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, (3-trimethoxy-silylpropyl) -diethylenetriamine, N- (n-butyl) -3-aminopropyltri It is preferably at least one selected from the group consisting of methoxysilane and a mixture thereof.
In addition, it is preferable that the surface-modified inorganic fine particles A, which are surface-modified with aminoorganosilane, contain at least one monovalent organic acid since the storage stability such as water resistance is improved.
The surface-modified inorganic fine particles A that are surface-modified with aminoorganosilane and the cationic polymer may be present in the same layer or in different layers. The ink receiving layer may contain inorganic fine particles in addition to the surface-modified inorganic fine particles A.

  The ink jet recording sheets according to the first to fourth inventions are formed on the surface through the roll nip under pressure with, for example, a super calender, gloss calender, or soft calender for the purpose of imparting high gloss after the ink receiving layer is formed. It is also possible to provide the smoothness. When the support is a gas permeable support, the surface of the ink receiving layer may be cast-processed.

"About glossy layer"
In the present invention, a gloss layer may be further provided on the ink receiving layer described above. Thereby, it can be set as the inkjet recording sheet with higher surface glossiness. The gloss layer is configured to contain a pigment and / or a resin. The gloss layer is preferably porous or liquid-permeable so long as it does not impair the gloss so that the ink can pass or absorb quickly.

  In an embodiment for carrying out the above method, at least one ink receiving layer coating liquid and the gloss layer coating liquid adjacent thereto are sequentially supplied from a coating liquid supply of a coating apparatus arranged independently of each other. To be applied. In this case, in particular, the coating apparatus that coats the outermost layer forming coating liquid on the wet coating liquid layer is a coating apparatus that does not come into contact with the wet inner layer forming coating liquid layer, such as a slot die coater (Inoue Metal Co., Ltd.). It is preferable to use an ultra die coater manufactured by Hiran Techseed Co., Ltd., a slide die coater, a curtain coater or the like.

  In another aspect for carrying out the above method, the coating liquid for forming the ink receptive outermost layer and the coating liquid for forming the ink receptive inner layer adjacent to the coating liquid of the simultaneous multilayer coating apparatus are used. It is applied almost simultaneously from the supply port. The simultaneous multi-layer coating method is a method in which two or more kinds of coating liquids are simultaneously applied to a desired surface in a single coating device, instead of sequentially coating with independent coating devices. In the case of the simultaneous multilayer coating method, the coating liquids for the respective layers are less likely to mix with each other, and it is easy to form a layer with a uniform film thickness. For simultaneous multilayer coating, it is preferable to use a multilayer slot die coater, a multilayer slide die coater, a multilayer slide curtain coater, or the like.

  Examples of the pigment 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 absorption. Zeolite, synthetic smectite and the like are preferable. Among these, colloidal silica and / or alumina are more preferable in terms of gloss and quality as other ink jet recording sheets. The term “alumina” as used herein is generally called aluminum oxide having crystallinity. In general, mention may be made of aluminum oxide having χ, κ, γ, δ, θ, η, ρ, pseudoγ, α crystals. In the present invention, alumina is preferable from the viewpoint of glossiness, ink absorbability, and pigment ink suitability, and alumina having γ, δ, and θ crystals is preferably selected. Vapor phase alumina (fumed alumina) having a sharp particle size distribution and particularly excellent film formability is most preferred. Vapor phase alumina is alumina formed by high temperature hydrolysis of gaseous aluminum trichloride, resulting in the formation of high purity alumina particles. The primary particle size of these particles is nano-order, and shows a very narrow particle size distribution (size distribution). Such vapor phase alumina has a cationic surface charge.

  These pigments are desirably contained in the gloss layer in an amount of 10 to 90% by mass. The average particle diameter of the pigment (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. When the particle diameter is in this range, excellent ink absorbability, gloss and print density can be obtained.

  Moreover, resin can be contained in a glossy layer as needed. Examples of the resin 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, carboxymethylcellulose, and methylcellulose). Cellulose derivatives), water-dispersible resins such as conjugated diene polymer latexes such as styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, vinyl copolymer latexes such as styrene-vinyl acetate copolymer, Various resins (adhesives) known and publicly known in the field of coated paper, such as acrylic resin, water-based polyurethane resin, water-based polyester resin, etc., can be used alone or in combination.

  When the gloss layer is formed mainly of a resin, the resin may be a polymer or copolymer obtained by polymerizing a monomer having an ethylenically unsaturated bond (hereinafter referred to as an ethylenic monomer). It is preferable that the main component is a combination. Furthermore, substituted derivatives of these polymers may be used. In addition, the above ethylenic monomer is polymerized in the presence of colloidal silica to form a composite by Si—O—R (R: polymer component) bond, or colloidal silica such as SiOH group is added to the polymer. 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.

  In addition, the glossy layer contains water-soluble metal salts and other cationic compounds to increase print density, improve water resistance, and various auxiliary agents to improve light resistance and gas resistance. It is also possible to add various cross-linking agents such as boron compounds and to blend plastic beads in order to adjust the frictional force. Further, a pigment having a particle diameter of 1 mm or more can be used as a matting agent in order to adjust the glossiness to a low level.

The coating amount of the glossy layer coating liquid is preferably 0.01 to 10 g / m ² by dry weight, 0.05-5 g / m ² is more preferable. When the coating amount is within this range, the gloss, ink drying property and recording density are excellent. The drying temperature of the ink receiving layer and / or gloss layer is also important. If the drying temperature is too high, film formation proceeds too much and the surface porosity decreases, resulting in a decrease in ink absorption rate. Conversely, if the drying temperature is too low, the gloss tends to be poor and the productivity also decreases. To do. The drying temperature is preferably 30 to 150 ° C, more preferably 40 to 100 ° C.

  In 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 on which the ink receiving layer is not formed) of the support, and the back surface is further adhered to the back surface. It can be processed, and various known techniques in the field of inkjet recording sheet production can be added.

"About ink"
The liquid ink for forming a recorded image on the ink jet recording sheet of the present invention is a recording liquid composed of a colorant, a liquid medium, and other optional additives, and any commercially available liquid ink for ink jet recording is used. Can be used. 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 these, 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% by mass or more of the water-soluble solvent, and the ink jet recording sheet of the present invention. Is preferable in terms of suitability for pigment ink, particularly in terms of 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 in more detail 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 mass% unless otherwise specified.

(Preparation of sol of surface-modified inorganic fine particles A-1 with aminoorganosiloxane)
15.2 parts of N- (2-aminoethyl) -3-aminopropyltrimethoxysilane (manufactured by Degussa, trade name: Dynasylan DAMO) was added to 738 parts of ion-exchanged water with stirring. After stirring for 10 minutes, 15.8 parts of a 20% formic acid aqueous solution were added with vigorous stirring. 206 g of vapor phase silica having a specific surface area of 200 m ² (manufactured by Cabot Corporation, trade name: Cab-O-Sil M-5) was added little by little at a high shear rate. The dispersion was then stirred for 15 minutes using a rotor-stator mixer. The dispersion was then heated to a temperature of 50 ° C. and maintained at that temperature for 30 minutes to completely modify the silica surface. By this method, a sol of surface-modified inorganic fine particles A-1 having a solid content concentration of 23% by mass and a pH = 6.30 was obtained. The molar ratio between aminosilane and silica is 2.0 mol%, and the molar ratio of formic acid to silica is 2.0 mol%.

(Preparation of sol of surface-modified inorganic fine particles B-1 by cationic polymer)
16 parts of a 50% by weight aqueous solution of polyallylamine hydrochloride having a molecular weight of about 15,000 (manufactured by Nittobo Co., Ltd., trade name: PAA-HCl-3L) and polyallylamine having a molecular weight of about 15,000 (manufactured by Nittobo) 13.3 parts of a 15% by weight aqueous solution of trade name: PAA-15C) is added to 518 parts of ion-exchanged water, and vapor phase silica having a specific surface area of 200 m ² (trade name: Cab-O-Sil M, manufactured by Cabot Corporation). -5) 100 parts were added in small portions at a high shear rate. Next, the dispersion was stirred for 15 minutes using a rotor / stator / mixer, and then treated using a wet ultrafine atomizer Nanomizer to obtain surface-modified inorganic fine particles B-1 having a solid concentration of 17% by mass. .

(Support A)
Softwood bleached kraft pulp (NBKP) in which CSF (JIS P-8121) is beaten to 250 ml and hardwood bleached kraft pulp (LBKP) in which CSF is beaten to 250 ml are mixed at a mass ratio of 2: 8. A pulp slurry having a concentration of 0.5% was prepared. In this pulp slurry, cationized starch 2.0%, alkyl ketene dimer 0.4%, anionized polyacrylamide resin 0.1% and polyamide polyamine epichlorohydrin resin 0.7% are added to the pulp dry weight. The mixture was sufficiently stirred and dispersed.
The pulp slurry having the above composition was made with a long net machine and passed through a dryer, a size press, and a machine calendar to produce a base paper having a basis weight of 180 g / m ² and a density of 1.0 g / cm ³ . The size press liquid used in the size press step was prepared by mixing carboxyl-modified polyvinyl alcohol and sodium chloride at a mass ratio of 2: 1, adding this to water and dissolving it by heating to prepare a concentration of 5%. A total of 25 ml / m ^{2 of} this size press solution was applied to both sides of the paper to obtain a support A (air permeability: 300 seconds).

(Support B)
The following polyolefin resin composition 1 that has been subjected to corona discharge treatment on both sides of the base paper of the support A and then mixed and dispersed with a Banbury mixer is applied to the felt surface side of the support A so that the coating amount is 25 g / m ^2. Further, the polyolefin resin composition 2 was applied to the wire side of the support A with a melt extruder (melting temperature: 320 ° C.) having a T die so that the coating amount was 20 g / m ^2, and felt. The smoothness (Oken type, J. TAPPI No. 5) on the side coated with the polyolefin resin composition 1 after cooling and solidifying with a cooling roller with a mirror surface on the surface side and a cooling roller with a rough surface on the wire surface side is 6000 seconds. A support B coated with a resin having an opacity (JIS P8138) of 93% was obtained. An ink receiving layer is provided on the surface side having a smoothness of 6000 seconds.

"Polyolefin resin composition 1"
Long chain type low density polyethylene resin (density 0.926 g / cm ³ , melt index 20 g / 10 min) 35 parts, low density polyethylene resin (density 0.919 g / cm ³ , melt index 2 g / 10 min) 50 parts, anatase Type titanium dioxide (trade name: A-220, manufactured by Ishihara Sangyo Co., Ltd.) 15 parts, zinc stearate 0.1 part, antioxidant (trade name: Irganox 1010, manufactured by Ciba Geigy) 0.03 parts, ultramarine (trade name) : Aoguchi Ultramarine NO.2000, manufactured by Daiichi Kasei Co., Ltd.) 0.09 part, and optical brightener (trade name: UVITEX OB, manufactured by Ciba Geigy Co., Ltd.) 0.3 part were mixed to obtain polyolefin resin composition 1.

"Polyolefin resin composition 2"
65 parts of high density polyethylene resin (density 0.954 g / cm ³ , melt index 20 g / 10 min) and 35 parts of low density polyethylene resin (density 0.919 g / cm ³ , melt index 2 g / 10 min) are melt mixed. A polyolefin resin composition 2 was obtained.

Example 1
(Preparation of coating liquid A for ink receiving layer)
After mixing 42.5 parts of the sol of the surface-modified inorganic fine particles A-1 and 57.5 parts of the sol of the surface-modified inorganic fine particles B-1, polyvinyl alcohol (manufactured by Kuraray Co., Ltd., trade name: PVA-224, degree of saponification). 88%, average polymerization degree 2,400) 10% by weight aqueous solution 39.2 parts, boric acid 0.78 parts and a small amount of antifoaming agent, dispersant and water were added, and the ink receiving layer having a solid content concentration of 15% by weight A coating liquid A was obtained.

(Formation of ink receiving layer)
The ink receiving layer coating liquid A was applied and dried on the support B with a Mayer bar so that the coating amount was 25 g / m ² to provide an ink receiving layer. The ink receiving layer had a thickness of 38 μm.

Example 2
(Preparation of coating liquid B for ink receiving layer)
After 87 parts of the sol of the surface-modified inorganic fine particles A-1 and 13 parts of the sol of the surface-modified inorganic fine particles B-1 were mixed, polyvinyl alcohol (manufactured by Kuraray Co., Ltd., trade name: PVA-224, saponification degree 88%, average) 44.5 parts of a 10% by weight aqueous solution having a degree of polymerization of 2,400), 0.90 part of boric acid and a small amount of an antifoaming agent, a dispersing agent and water were added, and a coating solution B for ink receiving layer having a solid content concentration of 15% by weight. Got.

(Formation of ink receiving layer)
The ink receiving layer coating liquid B was applied and dried on the support B with a Mayer bar so that the coating amount was 25 g / m ² to provide an ink receiving layer. The ink receiving layer had a thickness of 38 μm.

Example 3
(Preparation of coating liquid C for ink receiving layer)
After mixing 69 parts of the sol of the surface modified inorganic fine particles A-1 and 31 parts of the sol of the surface modified inorganic fine particles B-1, polyvinyl alcohol (manufactured by Kuraray Co., Ltd., trade name: PVA-224, saponification degree 88%, average) 42.3 parts of a 10% by weight aqueous solution having a polymerization degree of 2,400), 0.85 part of boric acid and a small amount of an antifoaming agent, a dispersing agent and water were added, and a coating liquid C for an ink receiving layer having a solid content concentration of 15% by weight. Got.

(Formation of ink receiving layer)
The ink receiving layer coating liquid C was applied onto the support B with a Mayer bar so that the coating amount was 25 g / m ² and dried to provide an ink receiving layer. The ink receiving layer had a thickness of 38 μm.

Example 4
(Preparation of coating liquid D for ink receiving layer)
After 19.5 parts of the sol of the surface-modified inorganic fine particles A-1 and 80.5 parts of the sol of the surface-modified inorganic fine particles B-1 were mixed, polyvinyl alcohol (manufactured by Kuraray Co., Ltd., trade name: PVA-224, degree of saponification) 88%, average polymerization degree 2,400) 10% by weight aqueous solution 36.5 parts, boric acid 0.85 parts and a small amount of antifoaming agent, dispersant and water were added, and the ink receiving layer having a solid concentration of 15% by weight A coating liquid D was obtained.

(Formation of ink receiving layer)
The ink receiving layer coating liquid D was applied and dried on the support B with a Mayer bar so that the coating amount was 25 g / m ² to provide an ink receiving layer. The ink receiving layer had a thickness of 38 μm.

Example 5
In Example 1, in place of 42.5 parts of the sol of the surface-modified inorganic fine particles A-1, 37.6 parts of the sol of the following surface-modified inorganic fine particles A-2 was used in the same manner as in Example 1, except that A recording sheet was obtained.
(Preparation of surface-modified inorganic fine particle A-2 sol with aminoorganosiloxane)
31.2 parts of 3-aminopropyltriethoxysilane (manufactured by Degussa, trade name: Dynasylan AMEO) was added to 717 parts of ion-exchanged water and stirred. After stirring for 10 minutes, 21.9 parts of a 20% aqueous formic acid solution was added with vigorous stirring. 230 g of vapor phase silica having a specific surface area of 200 m ² (manufactured by Cabot Corporation, trade name: Cab-O-Sil M-5) was added little by little at a high shear rate. The dispersion was then stirred for 15 minutes using a rotor-stator mixer. The dispersion was then heated to a temperature of 50 ° C. and maintained at that temperature for 30 minutes to completely modify the silica surface. By this method, a sol of surface-modified inorganic fine particles A-2 having a solid content concentration of 26% by mass and a pH = 6.30 was obtained. The molar ratio between aminosilane and silica is 3.6 mol%, and the molar ratio of formic acid to silica is 2.5 mol%.

Example 6
In Example 1, except that 42.5 parts of the sol of the surface-modified inorganic fine particles A-3 was used instead of 42.5 parts of the sol of the surface-modified inorganic fine particles A-1, the inkjet was performed in the same manner as in Example 1. A recording sheet was obtained.
(Preparation of surface-modified inorganic fine particle A-3 sol with aminoorganosiloxane)
18.1 parts of N- (2-aminoethyl) -3-aminopropyltrimethoxysilane (manufactured by Degussa, trade name: Dynasylan DAMO) was added to 744 parts of ion-exchanged water with stirring. After stirring for 10 minutes, 44.5 parts of L-lactic acid 20% aqueous solution was added with vigorous stirring. 206 g of vapor phase silica having a specific surface area of 200 m ² (manufactured by Cabot Corporation, trade name: Cab-O-Sil M-5) was added little by little at a high shear rate. The dispersion was then stirred for 15 minutes using a rotor-stator mixer. The dispersion was then heated to a temperature of 50 ° C. and maintained at that temperature for 30 minutes to completely modify the silica surface. By this method, a sol of surface-modified inorganic fine particles A-3 having a solid concentration of 23% by mass and a pH of 6.00 was obtained. In addition, the molar ratio between aminosilane and silica is 2.4 mol%, and the molar ratio of L-lactic acid to silica is 2.9 mol%.

Example 7
In Example 1, an inkjet was used in the same manner as in Example 1 except that 57.5 parts of the sol of the following surface-modified inorganic fine particles B-2 was used instead of 57.5 parts of the sol of the surface-modified inorganic fine particles B-1. A recording sheet was obtained.
(Preparation of sol of surface-modified inorganic fine particles B-2 by cationic polymer)
40 parts of a 20% by weight aqueous solution of a 50 mol% methoxycarbonyl-modified polyallylamine hydrochloride having a molecular weight of about 15,000 is added to 495 parts of ion-exchanged water, and gas phase method silica having a specific surface area of 200 m ² (manufactured by Cabot Corporation, product) Name: 100 parts Cab-O-Sil M-5) was added in small portions at high shear rate. Next, the dispersion was stirred for 15 minutes using a rotor / stator / mixer, and then treated with a wet micronizer Nanomizer to obtain a sol of surface-modified inorganic fine particles B-2 having a solid content concentration of 17% by mass. Obtained.

Example 8
In Example 1, an inkjet was used in the same manner as in Example 1, except that 57.5 parts of the sol of the following surface-modified inorganic fine particles B-3 was used instead of 57.5 parts of the sol of the surface-modified inorganic fine particles B-1. A recording sheet was obtained.
(Preparation of sol of surface-modified inorganic fine particles B-3 by cationic polymer)
20 parts of a 40% by weight aqueous solution of a copolymer of allylamine hydrochloride / diallylamine hydrochloride having a molecular weight of about 20,000 (manufactured by Nittobo Co., Ltd., trade name: PAA-D41-HCl), and polyallylamine having a molecular weight of about 15,000 ( 13.3 parts of a 15% by weight aqueous solution of Nittobo Co., Ltd., trade name: PAA-15C) is added to 514 parts of ion-exchanged water, and vapor phase silica having a specific surface area of 200 m ² (trade name: Cab, manufactured by Cabot Corporation). -O-Sil M-5) 100 parts were added in small portions at high shear rate. Next, the dispersion was stirred for 15 minutes using a rotor / stator / mixer, and then treated with a wet micronizer Nanomizer to obtain a sol of surface-modified inorganic fine particles B-3 having a solid content concentration of 17% by mass. Obtained.

Comparative Example 1
An ink jet recording sheet was obtained in the same manner as in Example 1 except that the ink receiving layer coating liquid E shown below was used instead of the ink receiving layer coating liquid A in Example 1.
(Preparation of coating liquid E for ink receiving layer)
100 parts of sol of surface-modified inorganic fine particles A-1, 46 parts of 10% by weight aqueous solution of polyvinyl alcohol (trade name: PVA-224, manufactured by Kuraray Co., Ltd., saponification degree 88%, average polymerization degree 2,400), boron 0.92 parts of an acid and a small amount of an antifoaming agent, a dispersing agent and water were added to obtain a coating liquid E for ink receiving layer having a solid content concentration of 15% by mass.

Comparative Example 2
An ink jet recording sheet was obtained in the same manner as in Example 1 except that the ink receiving layer coating liquid F shown below was used instead of the ink receiving layer coating liquid A in Example 1.
(Preparation of coating liquid F for ink receiving layer)
100 parts of sol of surface-modified inorganic fine particles B-1, 34 parts of 10% by weight aqueous solution of polyvinyl alcohol (trade name: PVA-224, manufactured by Kuraray Co., Ltd., saponification degree 88%, average polymerization degree 2,400), boron 0.68 parts of acid and a small amount of an antifoaming agent, a dispersing agent and water were added to obtain a coating liquid F for ink receiving layer having a solid content concentration of 15% by mass.

Example 9
(Preparation of coating liquid G for ink receiving layer)
100 parts of sol of surface-modified inorganic fine particles A-1, 46 parts of 10% by weight aqueous solution of polyvinyl alcohol (trade name: PVA-224, manufactured by Kuraray Co., Ltd., saponification degree 88%, average polymerization degree 2,400), boron 0.92 parts of an acid and a small amount of an antifoaming agent, a dispersant and water were added to obtain a coating liquid G for ink receiving layer having a solid content concentration of 15% by mass.

(Preparation of coating liquid H for ink receiving layer)
100 parts of sol of surface-modified inorganic fine particles B-1, 34 parts of 10% by weight aqueous solution of polyvinyl alcohol (trade name: PVA-224, manufactured by Kuraray Co., Ltd., saponification degree 88%, average polymerization degree 2,400), boron 0.68 parts of acid and a small amount of an antifoaming agent, a dispersing agent and water were added to obtain a coating liquid H for ink receiving layer having a solid concentration of 15% by mass.

(Formation of ink receiving layer)
The ink receiving layer coating liquid H was applied and dried on the support B so that the coating amount after drying with a Mayer bar was 12 g / m ² to provide an ink receiving layer lower layer. Further, after filling the pores in the ink receiving layer with water to remove excess water, the ink receiving layer coating liquid G is dried with a Mayer bar so that the coating amount becomes 12 g / m ^2. The ink receiving layer upper layer was provided by coating and drying. The total thickness of the ink receiving layer lower layer and the ink receiving layer upper layer was 37 μm.

Example 10
In Example 9, the ink receiving layer lower layer was coated with 16 g / m ² and the ink receiving layer upper layer was coated with 8 g / m ² on the ink receiving layer lower layer. A sheet was obtained.

Example 11
In Example 9, the ink receiving layer lower layer was coated with 18 g / m ² and the ink receiving layer upper layer was coated with 6 g / m ² on the ink receiving layer lower layer. A sheet was obtained.

Example 12
In Example 9, the ink receiving layer lower layer was coated with 8 g / m ² , and the ink receiving layer upper layer was coated with 16 g / m ² on the ink receiving layer lower layer. A sheet was obtained.

Example 13
In Example 9, the ink receiving layer lower layer was coated with 6 g / m ² , and the ink receiving layer upper layer was coated with 18 g / m ² on the ink receiving layer lower layer. A sheet was obtained.

Example 14
In Example 9, the same procedure as in Example 9 was performed except that the lower layer of the ink receiving layer was coated with 2.4 g / m ² and the upper layer of the ink receiving layer was coated with 21.6 g / m ² on the lower layer of the ink receiving layer. Thus, an ink jet recording sheet was obtained.

Example 15
(Formation of ink receiving layer)
The ink receiving layer coating solution G was applied and dried on the support B so that the coating amount after drying with a Mayer bar was 12 g / m ² , thereby providing an ink receiving layer lower layer. Further, after filling the pores in the lower layer of the ink receiving layer with water and removing excess water, the coating amount H after drying the ink receiving layer coating liquid H with a Mayer bar is 12 g / m ^2. An ink receiving layer upper layer was provided by coating and drying. The total thickness of the ink receiving layer lower layer and the ink receiving layer upper layer was 37 μm.

Example 16
In Example 15, the ink receiving layer lower layer was coated at 16 g / m ² , and the ink receiving layer upper layer was coated at 8 g / m ² on the ink receiving layer lower layer. A sheet was obtained.

Example 17
In Example 15, the ink receiving layer lower layer was coated with 18 g / m ² , and the ink receiving layer upper layer was coated with 6 g / m ² on the ink receiving layer lower layer. A sheet was obtained.

Example 18
In Example 15, the same procedure as in Example 15 was applied except that the lower layer of the ink receiving layer was applied at 21.6 g / m ² and the upper layer of the ink receiving layer was applied at 2.4 g / m ² on the lower layer of the ink receiving layer. Thus, an ink jet recording sheet was obtained.

Example 19
In Example 15, the ink receiving layer lower layer was coated with 8 g / m ² , and the ink receiving layer upper layer was coated with 16 g / m ² on the ink receiving layer lower layer. A sheet was obtained.

Example 20
In Example 15, except that the lower layer of the ink receiving layer was coated with 6 g / m ² and the upper layer of the ink receiving layer was coated with 18 g / m ² on the lower layer of the ink receiving layer. A sheet was obtained.

Example 21
(Preparation of sol of surface-modified inorganic fine particles B-4 by cationic polymer)
16 parts of a 50% by weight aqueous solution of polyallylamine hydrochloride having a molecular weight of about 15,000 (manufactured by Nittobo Co., Ltd., trade name: PAA-HCl-3L) and polyallylamine having a molecular weight of about 15,000 (manufactured by Nittobo) 13.3 parts of a 15% by weight aqueous solution (trade name: PAA-15C) is added to 717 parts of ion-exchanged water, and vapor phase silica having a specific surface area of 300 m ² (trade name: Cab-O-Sil M, manufactured by Cabot Corporation). -5) 100 parts were added in small portions at a high shear rate. Next, the dispersion was stirred for 15 minutes using a rotor / stator / mixer and then treated using a wet ultrafine atomizer Nanomizer to obtain a sol of surface-modified inorganic fine particles B-4 having a solid content concentration of 13% by mass. Obtained.

(Preparation of coating liquid J for ink receiving layer)
100 parts of sol of surface-modified inorganic fine particles B-4, 31 parts of 10% by weight aqueous solution of polyvinyl alcohol (trade name: PVA-224, manufactured by Kuraray Co., Ltd., saponification degree 88%, average polymerization degree 2,400), boron 0.60 parts of acid and a small amount of an antifoaming agent, a dispersant and water were added to obtain a coating liquid J for ink receiving layer having a solid content concentration of 10% by mass.

(Formation of ink receiving layer)
The ink receiving layer coating solution G was applied and dried on the support B so that the coating amount after drying with a Mayer bar was 21.6 g / m ² , thereby providing an ink receiving layer lower layer. Furthermore, after filling the pores in the lower layer of the ink receiving layer with water and removing excess water, the coating amount J of the ink receiving layer after drying with a Mayer bar was 2.4 g / m ² . The upper layer of the ink receiving layer was provided by coating and drying. The total thickness of the ink receiving layer lower layer and the ink receiving layer upper layer was 38 μm.

(Evaluation methods)
The ink jet recording sheets obtained in Examples 1 to 21 and Comparative Examples 1 and 2 were printed using an ink jet printer PIXUS iP7500 (dye ink system) manufactured by Canon Inc. The obtained inkjet recording sheet and its image were evaluated as follows, and the results are shown in Table 1.

[Print density]
Using the ink jet printer, black 100% solid printing was performed in an environment of 23 ° C. and a relative humidity of 50%, and left in the same environment for 24 hours. Thereafter, the print density was measured using a Gretag Macbeth reflection densitometer (manufactured by Gretag Macbeth, trade name: RD-19I). The numbers shown in the table are average values of five measurements.

[Ink absorbency]
Green solid gradation printing was performed with the ink jet printer, and the obtained image was visually observed to evaluate the level of ink absorbability. Evaluation criteria scored sensory evaluation of a printed image, and evaluated by (excellent) 10-1 (inferior).

As the evaluation of long-term storage stability, the following heat and humidity resistance, water resistance and light resistance were evaluated.
[Heat resistance]
Immediately after the ISO-400 image “Portrait” is printed in an environment of 23 ° C. and a relative humidity of 50%, it is stored in a constant temperature and humidity chamber of 30 ° C. and a relative humidity of 85% for 7 days. evaluated.
(Evaluation criteria)
Excellent: Occurrence of blemishes and discoloration over time is good and good. Good: Slight blemishes and discoloration over time are observed, but there is no problem in practical use. Impossible, a level that is problematic in practical use: Significant blurring over time is observed, and discoloration is also remarkable.

[Image evaluation after heat and humidity treatment (transparency)]
Immediately after the ISO-400 image “Portrait” was printed in an environment of 23 ° C. and 50% relative humidity, it was stored in a constant temperature and humidity chamber at 30 ° C. and 85% relative humidity for 7 days. The sex level was sensory evaluated.
(Evaluation criteria)
Excellent: Transparency of the image after processing is almost unchanged and good. Good: Slight decrease in transparency is observed, but it is at a level where there is no problem in practical use. Not possible: Transparency of the image is significantly reduced, causing a practically problematic level

〔water resistant〕
Black, cyan, magenta, yellow, red, green, and blue solid color printed images are printed in an environment of 23 ° C and relative humidity of 50%, left in the same environment for 24 hours, and then watered using a 2 ml dropper. One drop of water was dropped, and after 1 minute, the water remaining on the printing surface was transferred to a commercially available mat inkjet paper. The obtained results were visually observed to evaluate the water resistance level.
(Evaluation criteria)
Excellent: Almost no discoloration or color shift in the image and good. Good: Slight discoloration and color transfer were observed, but there was no problem in practical use. Impossible, practically problematic level: Discoloration and color transfer are remarkable.

[Light resistance]
An ISO-400 image “Portrait” was printed in an environment of 23 ° C. and a relative humidity of 50%, and left in that environment for 24 hours. Then, it processed for 72 hours in the environment of 24 degreeC and 60% of relative humidity using the xenon weather meter (Suga Test Instruments Co., Ltd. model WEL-7X-LHP). About the obtained result, the level of light resistance was evaluated by visual observation.
(Evaluation criteria)
Excellent: Almost no discoloration is observed and very good. Good: Slight discoloration is observed, but the color balance is not broken. Good: Discoloration is observed, at a practically problematic level. There is no: Discoloration is remarkable

  The ink jet recording sheets of Examples 1 to 8 are examples in which the surface-modified inorganic fine particles A and the surface-modified inorganic fine particles B according to the first invention are used in the same layer. Compared to comparative examples that are not used in combination, high-quality images are formed, aging blurring and discoloration hardly occur even under high temperature and high humidity, and even when exposed to light for a long time, the image discolors. It was an ink jet recording sheet with very few and excellent long-term storability.

  The ink jet recording sheets of Examples 9 to 14 are examples in which the surface-modified inorganic fine particles A according to the second invention are laminated on the upper layer of the ink receiving layer and the surface-modified inorganic fine particles B are laminated on the lower layer of the ink receiving layer. Compared to the comparative example in which the surface-modified inorganic fine particles A and the surface-modified inorganic fine particles B are used alone, a high-quality image is formed, and the occurrence of blurring and discoloration over time is hardly observed even under high temperature and high humidity. Even when exposed to light for a long time, the color of the image was very little changed, and the sheet for inkjet recording was excellent in long-term storage stability. Moreover, compared with Examples 1-8 used for the same layer, ink absorptivity becomes high. This tendency is remarkable when the coating amount of the upper layer of the ink receiving layer is increased.

  The ink jet recording sheets of Examples 15 to 21 are examples in which the surface-modified inorganic fine particles A according to the third invention are laminated on the lower layer of the ink receiving layer and the surface-modified inorganic fine particles B are laminated on the upper layer of the ink receiving layer. Compared to the comparative example in which the surface-modified inorganic fine particles A and the surface-modified inorganic fine particles B are used alone, a high-quality image is formed, and the occurrence of blurring and discoloration over time is hardly observed even under high temperature and high humidity. Even when exposed to light for a long time, the color of the image was very little changed, and the sheet for inkjet recording was excellent in long-term storage stability. Moreover, it is excellent in light resistance compared with Examples 15-21 used for the same layer. This tendency is remarkable when the coating amount of the lower layer of the ink receiving layer is increased.

  In addition, all the examples in which the surface-modified inorganic fine particles A surface-modified with at least one of aminoorganosilanes and the cationic polymer specified in the fourth invention are combined are capable of forming a high-quality image and have a high temperature. For ink jet recording with very good balance and excellent long-term storage, with little blurring or discoloration over time even under high humidity, and very little image discoloration even when exposed to light for a long time. It becomes a sheet.

  The present invention can be used for an inkjet recording sheet having an ink receiving layer containing inorganic fine particles, a cationic polymer and a binder on a support. In particular, it is possible to provide an ink jet recording sheet suitable for a dye-based or pigment-based ink jet printer that aims at photographic image quality and that ejects ink quickly.

Claims (18)

  In an inkjet recording sheet having at least one ink receiving layer containing inorganic fine particles and a binder on a support, the inorganic fine particles have an average primary particle size of 30 nm or less and at least one aminoorganosilane. The surface-modified inorganic fine particles A surface-modified by the above-mentioned method and the surface-modified inorganic fine particles B having an average primary particle diameter of 30 nm or less and surface-modified by at least one cationic polymer are used. Sheet.   Aminoorganosilane is 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyl-trimethoxysilane, (3-triethoxysilylpropyl) -diethylenetriamine, 3-aminopropyl-triethoxysilane N- (2-aminoethyl) -3-aminopropyltriethoxysilane, (3-trimethoxy-silylpropyl) -diethylenetriamine, N- (n-butyl) -3-aminopropyltrimethoxysilane and mixtures thereof The inkjet recording sheet according to claim 1, which is at least one selected from the group consisting of:   3. The ink jet recording sheet according to claim 1, wherein the surface-modified inorganic fine particles A are surface-modified in the presence of at least one monovalent organic acid and aminoorganosilane. The cationic polymer is at least one structural unit (b1) represented by the following general formula (1) or general formula (2), and at least one structural unit (b2) represented by the following general formula (3). And at least one structural unit (b3) represented by the following general formulas (4) to (7): a polymer having at least one structural unit selected from structural units. An ink jet recording sheet according to claim 1.

[Wherein, X represents an acid residue. ]

[Wherein, R ¹ represents an alkyl group having 1 to 18 carbon atoms, an alkoxyl group having 1 to 18 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a benzyl group. ]

[Wherein, R ^{2 to} R ⁹ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and Y and Z each represents an independent acid residue. ]   The inkjet recording sheet according to any one of claims 1 to 4, wherein the ratio of the surface-modified inorganic fine particles A to the surface-modified inorganic fine particles B is 99: 1 to 1:99.   In the inkjet recording sheet having at least two ink receiving layers containing inorganic fine particles and a binder on the support, the inorganic fine particles in the lower layer of the ink receiving layer close to the support have an average primary particle size of 30 nm or less, The surface-modified inorganic fine particles B are surface-modified with at least one cationic polymer, the inorganic fine particles in the upper layer of the ink receiving layer far from the support have an average primary particle size of 30 nm or less, and at least one of the aminoorganosilanes. An ink jet recording sheet comprising surface-modified inorganic fine particles A surface-modified with seeds.   Aminoorganosilane is 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyl-trimethoxysilane, (3-triethoxysilylpropyl) -diethylenetriamine, 3-aminopropyl-triethoxysilane N- (2-aminoethyl) -3-aminopropyltriethoxysilane, (3-trimethoxy-silylpropyl) -diethylenetriamine, N- (n-butyl) -3-aminopropyltrimethoxysilane and mixtures thereof The inkjet recording sheet according to claim 6, which is at least one selected from the group consisting of:   8. The ink jet recording sheet according to claim 6 or 7, wherein the surface-modified inorganic fine particles A are surface-modified in the presence of at least one monovalent organic acid and aminoorganosilane. The cationic polymer is at least one structural unit (b1) represented by the following general formula (1) or general formula (2), and at least one structural unit (b2) represented by the following general formula (3). And at least one structural unit (b3) represented by the following general formulas (4) to (7): a polymer having at least one structural unit selected from structural units. An ink jet recording sheet according to claim 1.

[Wherein, X represents an acid residue. ]

[Wherein, R ¹ represents an alkyl group having 1 to 18 carbon atoms, an alkoxyl group having 1 to 18 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a benzyl group. ]

[Wherein, R ^{2 to} R ⁹ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and Y and Z each represents an independent acid residue. ]   The ink jet recording sheet according to any one of claims 6 to 9, wherein the ratio of the coating amount of the ink receiving layer lower layer and the ink receiving layer upper layer is 1:99 to 99: 1.   In the inkjet recording sheet having at least two ink receiving layers containing inorganic fine particles and a binder on the support, the inorganic fine particles in the lower layer of the ink receiving layer close to the support have an average primary particle size of 30 nm or less, In addition, the surface-modified inorganic fine particles A are surface-modified with at least one kind of aminoorganosilane, the inorganic fine particles in the upper layer of the ink receiving layer far from the support have an average primary particle size of 30 nm or less, and at least one cationic polymer. An ink jet recording sheet, which is surface-modified inorganic fine particles B surface-modified with seeds.   Aminoorganosilane is 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyl-trimethoxysilane, (3-triethoxysilylpropyl) -diethylenetriamine, 3-aminopropyl-triethoxysilane N- (2-aminoethyl) -3-aminopropyltriethoxysilane, (3-trimethoxy-silylpropyl) -diethylenetriamine, N- (n-butyl) -3-aminopropyltrimethoxysilane and mixtures thereof The inkjet recording sheet according to claim 11, which is at least one selected from the group consisting of:   The sheet for inkjet recording according to claim 11 or 12, wherein the surface-modified inorganic fine particles A are surface-modified in the presence of at least one monovalent organic acid and aminoorganosilane. The cationic polymer is at least one structural unit (b1) represented by the following general formula (1) or general formula (2), and at least one structural unit (b2) represented by the following general formula (3). And at least one structural unit (b3) represented by the following general formulas (4) to (7): a polymer having at least one structural unit selected from structural units. An ink jet recording sheet according to claim 1.

[Wherein, X represents an acid residue. ]

[Wherein, R ¹ represents an alkyl group having 1 to 18 carbon atoms, an alkoxyl group having 1 to 18 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a benzyl group. ]

[Wherein, R ^{2 to} R ⁹ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and Y and Z each represents an independent acid residue. ]   The ink jet recording sheet according to claim 11, wherein the ratio of the coating amount of the ink receiving layer lower layer and the ink receiving layer upper layer is 1:99 to 99: 1. In an inkjet recording sheet having at least one ink receiving layer containing inorganic fine particles and a binder on a support, the inorganic fine particles have an average primary particle diameter of 30 nm or less and at least one aminoorganosilane. The surface-modified inorganic fine particles A that have been surface-modified by at least one ink receiving layer and at least one cationic polymer, and the cationic polymer is represented by the following general formula (1) or general formula (2): And at least one structural unit (b2) represented by the following general formula (3), and at least represented by the following general formulas (4) to (7). Ink characterized in that it is a polymer having at least one structural unit selected from the structural units (b3). Jet recording sheet.

[Wherein, X represents an acid residue. ]

[Wherein, R ¹ represents an alkyl group having 1 to 18 carbon atoms, an alkoxyl group having 1 to 18 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a benzyl group. ]

[Wherein, R ^{2 to} R ⁹ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and Y and Z each represents an independent acid residue. ]   Aminoorganosilane is 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyl-trimethoxysilane, (3-triethoxysilylpropyl) -diethylenetriamine, 3-aminopropyl-triethoxysilane N- (2-aminoethyl) -3-aminopropyltriethoxysilane, (3-trimethoxy-silylpropyl) -diethylenetriamine, N- (n-butyl) -3-aminopropyltrimethoxysilane and mixtures thereof The inkjet recording sheet according to claim 16, which is at least one selected from the group consisting of:   18. The ink jet recording sheet according to claim 16, wherein the surface-modified inorganic fine particles A surface-modified with aminoorganosilane contain at least one monovalent organic acid.