JP2007008131A - Inkjet recording sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording sheet which has high image quality, high gloss and excellent ink absorbency, which greatly improves the long-term storage stability of a recorded image, and which is excellent in the suppression of the discoloration of the recorded image with time and bleeding on the recorded image. <P>SOLUTION: This inkjet recording sheet comprises an ink absorbing layer containing low-molecular-weight organic gelled compounds which are expressed by general formulae (1) and (2). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet recording sheet, and more particularly, to an ink jet recording sheet having high image quality, high gloss, excellent ink absorbability, and excellent suppression of aging of recorded images over time in a high temperature and high humidity environment. .

  In recent years, along with the rapid spread of digital cameras and personal computers, the ink-jet method, sublimation type thermal transfer method, static electricity as hard copy technology for recording character information and images output from them on paper-like sheet media. A small recording method such as an electrotransfer method, which does not require plate making or development / washing, has been rapidly developed. Among these, the ink jet method for forming an image by ejecting liquid ink from a fine nozzle onto a recording medium has advantages such as a relatively small apparatus and low running cost. Alternatively, it is widely used not only in offices such as form printing, but also in home use, and is firmly established as a standard output device at the so-called consumer level. In addition, the ink jet system has been further promoted by rapidly advancing the technology in the apparatus and achieving a high definition and high speed that can be used for commercial printing.

  On the other hand, along with the improvement in performance of inkjet printers, the custom of printing images taken by individual users with a digital camera via a personal computer has become well established. New characteristics are now required. That is, there is a strong demand for an ink jet recording body that has both image absorbability and recording density, as well as image quality and storage stability comparable to silver salt photography.

  Therefore, in order to improve ink absorption, recording density, image quality, etc., for example, Japanese Patent Laid-Open Nos. 55-51583 (Patent Document 1), 56-157 (Patent Document 2), and 57-107879 (Patent Document). Document 3), 57-107880 (Patent Document 4), 59-230787 (Patent Document 5), 62-183382 (Patent Document 6), 62-184879 (Patent Document 7) and 64. JP-A-11877 (Patent Document 8) proposes a method of providing an ink receiving layer containing inorganic fine particles such as amorphous silica on a support together with a binder.

  In order to obtain gloss and high image quality, Japanese Patent Publication No. 3-56552 (Patent Document 9), Japanese Patent Application Laid-Open Nos. 2-188287 (Patent Document 10), 10-81064 (Patent Document 11), and 10-119423 are disclosed. (Patent Document 12), 10-175365 (Patent Document 13), 10-193976 (Patent Document 814), 10-203006 (Patent Document 15), and 10-217601 (Patent Document 16). 11-20300 (patent document 17), 11-20306 (patent document 18), 11-34481 (patent document 19), and JP 2000-336357 (patent document 20). An ink receiving layer containing synthetic silica fine particles is provided on a water-resistant support such as a resin-coated paper coated on both sides with a polyolefin such as polyethylene. It has been proposed.

In addition, dyes that are the main component of inkjet inks can be exposed to light from the sun, fluorescent lamps, and other oxidizing gases such as ozone, nitrogen oxides, and sulfur oxides for a relatively short period of time. In order to solve the problem of discoloration of the recorded image (storability of the recorded image), metal oxides such as phosphotungstic acid, phosphomolybdic acid, and chromic chloride, metal chloride, or tannic acid Of adding at least one of them [JP-A 57-87
987 (Patent Document 21)], a method of adding an antioxidant such as hindered phenols and hindered amines [JP 57-74192 (Patent Document 22), JP 61-14659 1 (Patent Document) 23), Japanese Patent Publication No. 04-34512 (Patent Document 24)], a method of adding an ultraviolet absorber such as benzophenone, benzotriazole, or phenylsalicylic acid [Japanese Patent Laid-Open No. 57-74193 (Patent Document 25). ), 57-87988 (Patent Document 26), and 63-2222885 (Patent Document 27)], a method of adding a thiourea compound [Japanese Patent Laid-Open No. 61-163886 (Patent Document 28) ], Specific mercapto compounds such as 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, etc. No. 177279 (Patent Document 29)], a method of adding a dithiocarbamate, thiuram salt, thiocyanate or thiocyanate [JP-A-7-314882 (Patent Document 30)], basic polyaluminum hydroxide Have been proposed [Japanese Patent Laid-Open No. 60-257286 (Patent Document 31)], a method of adding a zirconium oxychloride-based active inorganic polymer [Japanese Patent Laid-Open No. 4-7189 (Patent Document 32)], and the like. Yes.

  Similarly, since inkjet ink is generally water-soluble, there is a problem that the recorded image is inferior in water resistance (water resistance of the recorded image). To improve this, JP-A-56-84992 (patent) Document 33), 60-49990 (Patent Document 34), 61-125878 (Patent Document 35), and 57-36692 (Patent Document 36), etc. include cationic polymers or basic latex. There has been proposed a method of incorporating it in the ink receiving layer.

  However, full-color inkjet recording images formed using these techniques are excellent in image quality and ink absorbability, and it has become possible to expect a certain degree of preservation of recorded images even when exposed to light or acid gas. However, it is a so-called photographic paper type ink jet recording body that complains about photographic image quality and high glossiness (in many cases, like photographic paper, water-resistant support with a resin coating such as polyethylene on both sides of the paper surface) Discoloration and blurring occur during long-term storage, especially in high-temperature and high-humidity environments, as well as during storage in files or sealed albums immediately after printing. The problem (image stability over time) has not been completely solved.

  The water-resistant support represented by the resin-coated paper coated on both sides of the paper with polyolefin such as polyethylene as described above absorbs ink, unlike the paper support that has been generally used for inkjet recording materials. Since water or other water-soluble ink solvent cannot be evaporated from the back side to accelerate drying of the recorded matter, ink (especially glycerin contained in a small amount in the ink) is formed on the ink receiving layer provided on the support. And high boiling alcohol solvents such as diethylene glycol derivatives) remain for a long period of time, which is a direct cause of the deterioration of the stability of recorded images over time.

In addition, since the ink solvent remains in the ink receiving layer, the storage stability of the recorded image such as light resistance and gas resistance is also impaired. Kenji et al., Polymer Proceedings, 52 (12), 773 (1995) (Non-patent Document 1), Kenji Ei, Shirai Yasuyoshi, Surface, 36 (6), 291-303 (1998) (Non-patent Document 2) , Kenji et al., Polymer Proceedings, 55 (10), 585 (1998) (Non-patent Document 3), Kenji Eiji, Shigeyoshi Shirai, Surface, 38 (12), 569-579 (2000) (Non-patent Document) 4), K. Hanabusa et.al., J. Chem. Soc., Chem. Commun., 390-392 (1993) (Non-Patent Document 5), K. Hanabusa et.al., Adv. Mater., 9 (14), 1095-1097 (1997) (Non-Patent Document 6)
), K. Hanabusa et.al., Chem. Mater., 11 (3), 649-655 (1999) (non-patent document 7), etc.) For example, it is made by each gazette of Unexamined-Japanese-Patent No. 2002-79743 (patent document 37), 2003-25721 (patent document 38), etc. However, they cause problems such as color development, image sharpness deterioration, and ink absorbability, and are not preferable for suppressing blurring of recorded images over time. Further, as disclosed in JP-A-2004-255690 (Patent Document 39), an ink solvent gelation layer comprising a gelling agent and a hydrophilic binder is provided in addition to the ink receiving layer, so that the recorded image is faded over time. There is also a proposal to suppress it at the same time, but the gelled layer composed of only the gelling agent and the hydrophilic binder has its ink solvent holding capacity and holding power greatly limited, and its effect is partial. stay.

JP-A-55-51583 JP-A-56-157 JP-A-57-107879 JP-A-57-107880 JP 59-230787 A JP-A-62-183382 Japanese Patent Laid-Open No. 62-184879 Japanese Patent Laid-Open No. 64-11877 Japanese Patent Publication No. 3-56552 Japanese Patent Laid-Open No. 2-188287 Japanese Patent Laid-Open No. 10-81064 JP 10-119423 A JP-A-10-175365 Japanese Patent Application Laid-Open No. 10-193776 Japanese Patent Laid-Open No. 10-203006 Japanese Patent Laid-Open No. 10-217601 Japanese Patent Laid-Open No. 11-20300 JP-A-11-20306 Japanese Patent Laid-Open No. 11-34481 JP 2000-336357 A JP-A-57-87987 JP-A-57-74192 JP-A 61-146591 Japanese Patent Publication No. 04-34512 JP-A-57-74193 JP-A-57-87988 Japanese Patent Laid-Open No. 63-222885 JP 61-163886 A JP-A 61-177279 JP 7-314882 A JP-A-60-257286 Japanese Patent Laid-Open No. 4-7189 JP 56-84992 A JP-A-60-49990 JP-A 61-125878 JP 57-36692 A JP 2002-79743 A JP 2003-25721 A JP 2004-255690 A Eiji Kenji et al., Polymer Papers, 52 (12), 773 (1995) Eiji Kenji, Shirai Yasuyoshi, Surface, 36 (6), 291-303 (1998) Eiji Kenji et al., Polymer Papers, 55 (10), 585 (1998) Eiji Kenji, Shirai Yasuyoshi, Surface, 38 (12), 568-579 (2000) K. Hanabusa et.al., J. Chem. Soc., Chem. Commun., 390-392 (1993) K. Hanabusa et.al., Adv. Mater., 9 (14), 1095-1097 (1997) K. Hanabusa et.al., Chem. Mater., 11 (3), 649-655 (1999)

  The present invention has high image quality comparable to silver salt photography, high gloss, excellent ink absorbency, and greatly improved long-term storage stability of recorded images, especially in storage in a high temperature and high humidity environment, immediately after printing. Another object of the present invention is to provide an ink jet recording sheet that is excellent in suppressing discoloration and blurring of recorded images over time even when stored in plastic files, sealed albums, or in a stacked state.

  As a result of diligent investigation to achieve the above object, the present inventors have overcome specific problems, and as a result, a specific low molecular weight organic compound capable of gelling an alcohol-based water-soluble solvent having a specific structure. In addition to being able to achieve both high image quality, high gloss and excellent ink absorbency of silver salt photographic like, the long-term storage stability of images, especially storage in high-temperature and high-humidity environments, It has been clarified that discoloration and blurring of recorded images over time can be suppressed in plastic files immediately after printing, sealed albums, or storage in a stacked state, and the inkjet recording sheet of the present invention has been completed. It was. The present invention includes the following inventions.

〔式（１）中、Ｒ¹は炭素数１〜８のアルキル基又はベンジル基を、Ｒ²は側鎖を有する二価の有機基、Ｒ³は二価の有機基、Ｒ⁴は炭素数１〜２２のアルキル基を表し、ｎは１〜８の整数、ｍは０〜８の整数を示す。
また、式（２）中、Ｒ⁵は炭素数１〜８のアルキル基又はベンジル基を、Ｒ⁶は側鎖を有する二価の有機基、Ｒ⁷及びＲ⁸は、互いに独立な二価の有機基を表し、ｐは１〜８の整、ｑは０〜８の整数を示す。〕
で表される、アルコール系の水溶性有機溶剤をゲル化することのできる低分子有機化合物から選ばれる少なくとも一種を含むインク受容層を支持体上に有するインクジェット記録シート。 (1) The following general formulas (1) and (2):

In [Equation (1), the R ¹ is an alkyl group or a benzyl group having 1 to 8 carbon atoms, R ² is a divalent organic group having a side chain, R ³ is a divalent organic group, R ⁴ is the number of carbon atoms Represents an alkyl group of 1 to 22, n represents an integer of 1 to 8, and m represents an integer of 0 to 8.
In Formula (2), R ⁵ is an alkyl group having 1 to 8 carbon atoms or a benzyl group, R ⁶ is a divalent organic group having a side chain, and R ⁷ and R ⁸ are divalent divalent groups. An organic group is represented, p is an integer of 1-8, q shows the integer of 0-8. ]
An ink jet recording sheet having an ink receiving layer containing at least one selected from low molecular weight organic compounds capable of gelling an alcohol-based water-soluble organic solvent represented on the substrate.

(2) The inkjet recording sheet according to item (1), wherein the support is a water-resistant support.

(3) The ink receiving layer is composed of at least two ink receiving layers each including at least one kind of inorganic fine particles and an aqueous polymer binder, and the ink receiving layer provided immediately above the support is the alcohol. A low molecular weight organic compound that is an ink-receiving layer containing at least one selected from low molecular weight organic compounds capable of gelling water-based organic solvents, and that can gel the water-soluble organic solvents based on alcohols The ink jet recording sheet according to item (1) or (2), wherein the content of is 1 to 35 parts when the mass part of the inorganic fine particles contained in the ink receiving layer is 100 parts .

(4) At least one of the inorganic fine particles contained in the ink receiving layer provided immediately above the support has an average primary particle size of 50 nm or less and an average secondary particle size of 1.0 μm or less. The inkjet recording sheet according to (3), which is amorphous anionic silica produced by a wet method and having a specific surface area of 200 m ² / g or more by the BET method.

(5) The inkjet recording sheet according to (4), wherein at least one of the amorphous anionic silicas produced by the wet method is a wet method silica produced by a gel method.

(6) At least one of the amorphous anionic silica produced by the wet process is a wet process secondary fine silica produced by condensing activated silicic acid (4) Item or the inkjet recording sheet according to item (5).

(7) Above the ink receiving layer provided immediately above the support, at least one cationic substance selected from silica, aluminosilicate, and alumina having an average primary particle diameter of 3 nm to 50 nm as inorganic fine particles. Item (1) to (1), wherein an ink receiving layer containing a fine pigment and at least one water-soluble polymer and having a function of mainly capturing and fixing a dye in the ink is laminated. The inkjet recording sheet according to any one of items 6).

(8) At least one of the cationic fine pigments is a composite fine particle of vapor phase method silica having an average primary particle size of 30 nm or less and a cationic inorganic compound and / or a cationic organic compound. The inkjet recording sheet according to item (7), wherein

（式中、Ｘは酸残基を示す。）
で表される構成単位を含む重量平均分子量が１００００以上、２０００００未満であるカチオンポリマー（Ａ）、及び／又は下記一般式（４）又は（５）：

（式中、Ｙは酸残基を示す。）
で表される少なくとも１種の構成単位（ｂ１）と、下記一般式（６）：

（式中、Ｒ⁹は炭素数１〜１８のアルキル基、炭素数１〜１８のアルコキシキル基、炭素
数６〜１２のアリール基又はベンジル基を示す。）
で表される少なくとも１種の構成単位（ｂ２）とを含む、重量平均分子量が１００００以上、２０００００未満であり、且つ構成単位ｂ１と構成単位ｂ２とのモル比が０．５：１〜２０：１であるカチオンポリマー（Ｂ）、との複合微粒子であることを特徴とする（７）項又は（８）項に記載のインクジェット記録シート。 (9) At least one of the cationic fine pigments is vapor phase silica having an average primary particle size of 30 nm or less, and the following general formula (3)

(In the formula, X represents an acid residue.)
And a cationic polymer (A) having a weight average molecular weight of 10,000 or more and less than 200,000, and / or the following general formula (4) or (5):

(In the formula, Y represents an acid residue.)
At least one structural unit (b1) represented by the following general formula (6):

(In the formula, R ⁹ represents an alkyl group having 1 to 18 carbon atoms, an alkoxyalkyl group having 1 to 18 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a benzyl group.)
The weight average molecular weight is 10,000 or more and less than 200,000, and the molar ratio of the structural unit b1 to the structural unit b2 is 0.5: 1 to 20: The ink jet recording sheet according to item (7) or (8), wherein the ink jet recording sheet is a composite fine particle with a cationic polymer (B) being 1.

(10) On the at least one ink receiving layer containing the inorganic fine particles and the aqueous polymer binder, an aqueous solution containing a cationic polymer is applied to form a water-coating layer, and then the cationic fine pigment and the water-soluble layer are dissolved. The inkjet recording sheet according to any one of (3) to (9), wherein at least one other ink receiving layer including an ink receiving layer containing a polymer is provided.

(11) The inkjet recording sheet according to (10), wherein the aqueous solution containing the cationic polymer further contains a crosslinking agent.

(12) The inkjet recording sheet according to any one of (1) to (11), wherein the water-resistant support is a support in which both sides of paper are coated with a polyolefin resin.

(13) The ink jet recording sheet according to any one of (1) to (12), wherein the ink jet recording sheet has an ink receiving layer subjected to a cast treatment.

(14) The ink jet recording sheet according to any one of items (1) to (13), wherein the ink jet recording sheet has a glossy expression layer in which an upper layer is casted from the ink receiving layer.

The ink jet recording sheet of the present invention has a high gloss, high quality image formed, and is stored in a high temperature and high humidity environment, or in a plastic file immediately after printing, in a sealed type album, or in a stacked state. This is an ink jet recording sheet that is excellent in storability of a recorded image in which the recorded image does not discolor over time and no blurring occurs even in storage.

The inkjet recording sheet of the present invention has a specific structure represented by the general formulas (1) and (2), and includes a low molecular organic compound capable of gelling an alcohol-based water-soluble solvent. It is characterized by
Hereinafter, a low molecular weight organic compound (hereinafter, sometimes simply referred to as a gelling agent) capable of gelling an alcohol-based water-soluble solvent having a specific structure used in the present invention will be described.

〔式（１）中、Ｒ¹は炭素数１〜８のアルキル基又はベンジル基を、Ｒ²は側鎖を有する二価の有機基、Ｒ³は二価の有機基、Ｒ⁴は炭素数１〜２２のアルキル基を表し、ｎは１〜８の整数、ｍは０〜８の整数を示す。また、式（２）中、Ｒ⁵は炭素数１〜８のアルキル基
又はベンジル基を、Ｒ⁶は側鎖を有する二価の有機基、、Ｒ⁷及びＲ⁸は、互いに独立な二
価の有機基を表し、ｐは１〜８の整、ｑは０〜８の整数を示す。〕
で表されるアルコール系の水溶性有機溶剤をゲル化することのできる低分子有機化合物の少なくとも一種である。 The low molecular organic compound capable of gelling the alcohol-based water-soluble solvent having a specific structure used in the present invention is represented by the following general formulas (1) and (2):

In [Equation (1), the R ¹ is an alkyl group or a benzyl group having 1 to 8 carbon atoms, R ² is a divalent organic group having a side chain, R ³ is a divalent organic group, R ⁴ is the number of carbon atoms Represents an alkyl group of 1 to 22, n represents an integer of 1 to 8, and m represents an integer of 0 to 8. In Formula (2), R ⁵ is an alkyl group having 1 to 8 carbon atoms or a benzyl group, R ⁶ is a divalent organic group having a side chain, and R ⁷ and R ⁸ are divalent independently of each other. P represents an integer of 1 to 8, and q represents an integer of 0 to 8. ]
It is at least 1 type of the low molecular weight organic compound which can gelatinize the alcohol-type water-soluble organic solvent represented by these.

In the general formula (1), R ¹ represents an alkyl group having 1 to 8 carbon atoms or a benzyl group. Specific examples include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, and an n-butylmethylene. A substituent selected from a group, an iso-butyl group, a tert-butyl group, an n-hexylmethylene group, a cyclohexyl group, an octyl group, a 2-ethylhexyl group, a benzyl group, and the like, preferably an ethyl group or a benzyl group .
R ² represents a divalent organic group having a side chain, and is preferably a kind selected from an alkylene group having 1 to 8 carbon atoms as a side chain. Specifically, methylmethylene group, ethylmethylene group, n-propylmethylene group, iso-propylmethylene group, n-butylmethylene group, iso-butylmethylene group, tert-butylmethylene group, n-hexylmethylene group, etc. More preferred are a methylmethylene group, an iso-propylmethylene group, and an iso-butylmethylene group.

R ³ represents a divalent organic group, and is a kind selected from an alkylene group having 1 to 6 carbon atoms and an alkylene group having 1 to 6 carbon atoms having a side chain of an alkyl group having 1 to 8 carbon atoms. Preferable examples are methylene group, ethylene group, propylene group, tetramethylene group, methylmethylene group, ethylmethylene group, n-propylmethylene group, iso-propylmethylene group, n-butylmethylene group, iso-butyl. A methylene group, a tert-butylmethylene group, an n-hexylmethylene group, and the like, and a methylene group, an ethylene group, a methylmethylene group, an iso-propylmethylene group, and an iso-butylmethylene group are more preferable.
On the other hand, R ⁴ represents an alkyl group having 1 to 22 carbon atoms, and is preferably a kind selected from 6 to 22 alkyl groups having a multiple of 2 carbon atoms, specifically, an octyl group (C8 ), Decyl group (C10), lauryl group (C12), mythyl group (C14), palmityl group (C16), stearyl group (C18), and the like.
In the formula, n represents an integer of 1 to 8, preferably 1 or 2, and m in the formula represents an integer of 0 to 8, preferably 0, 1 or 2. is there.

In the general formula (2), R ⁵ represents an alkyl group having 1 to 8 carbon atoms or a benzyl group. Specifically, a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-propyl group, A substituent selected from a butylmethylene group, an iso-butyl group, a tert-butyl group, an n-hexylmethylene group, a cyclohexyl group, an octyl group, a 2-ethylhexyl group, a benzyl group, and the like, preferably an ethyl group or a benzyl group .
R ⁶ represents a divalent organic group having a side chain, and is preferably a kind selected from an alkylene group having 1 to 8 carbon atoms as a side chain. Is a methylmethylene group, ethylmethylene group, n-propylmethylene group, iso-propylmethylene group, n-butylmethylene group, iso-butylmethylene group, tert-butylmethylene group, n-hexylmethylene group, etc. A methylene group, an iso-propylmethylene group, and an iso-butylmethylene group are more preferable.

R ⁷ represents a divalent organic group and is a kind selected from an alkylene group having 1 to 6 carbon atoms and an alkylene group having 1 to 8 carbon atoms as a side chain. Specifically, methylene group, ethylene group, propylene group, tetramethylene group, methylmethylene group, ethylmethylene group, n-propylmethylene group, iso-propylmethylene group, n-butylmethylene group, iso- A butylmethylene group, a tert-butylmethylene group, an n-hexylmethylene group, and the like, and a methylene group, an ethylene group, a methylmethylene group, an iso-propylmethylene group, and an iso-butylmethylene group are more preferable.
Further, in the formula, R ⁸ represents a divalent organic group, for example, an alkylene group, an arylene group,
It is a divalent organic group selected from aralkylene groups and the like, preferably one kind selected from alkylene groups having 1 to 22 carbon atoms, such as ethylene group, propylene group, tetramethylene group, hexamethylene group, octamethylene group, A decamethylene group, a dodecamethylene group, a tetradecylene group, a hexasilene group, an octadecylene group, an icosylene group, a docosylene group, and the like.
In addition, although p in a formula represents the integer of 1-8, Preferably, it is 1 or 2, Moreover, q in a formula represents the integer of 0-8, Preferably, it is 1 or 2.

  Among the gelling agents represented by the general formulas (1) and (2), for example, 0.5 g or less of the gelling agent is added to 10 g of glycols such as ethylene glycol and diethylene glycol, glycerin, or trimethylolpropane. Thus, a compound having the ability to form a state in which the whole becomes a gel after dissolution or suspension and does not flow even when the container is tilted is preferably used.

Specific examples of the gelling agent represented by the general formulas (1) and (2) contained in the inkjet recording sheet of the present invention include N-benzyloxycarbonyl-L-valine octadecylamide, N-benzyloxycarbonyl-L. -Valinyl-L-valine octylamide, N-benzyloxycarbonyl-L-valinyl-L-valine octadecylamide, N-benzyloxycarbonyl-L-valinyl-L-valine palmitylamide, N-benzyloxycarbonyl-L- Valinyl-L-valine octadecylamide, N-benzyloxycarbonyl-L-leucyl-β-alanine octadecylamide, N-benzyloxycarbonyl-L-valinyl-β-alanine octadecylamide, N, N′-dibenzyloxycarbonyl- L-isoleucine-1,1 -Dodecanyl diamide, N, N'-dibenzyloxycarbonyl-L-valine-1,12-dodecanyl diamide, N, N'-diethoxycarbonyl-L-isoleucine-1,12-dodecanyl diamide, N, N′-diethoxycarbonyl-L-valine-1,12-dodecanyldiamide, N, N′-diethoxycarbonyl-L-valine ethylenediamide, N, N′-dibenzyloxycarbonyl-L
Examples include -valinyl-L-valine-1,20-icosyl diamide, but the present invention is not limited thereto.

  In the ink jet recording sheet of the present invention, the content of the gelling agent represented by the general formulas (1) and (2) is not particularly limited, but it may cause discoloration or blurring of a recorded image in a high temperature and high humidity environment. On the other hand, in order to stably exhibit an excellent suppression effect, when the mass of the inorganic fine particles contained in the ink receiving layer is 100 parts, it is preferably 1 to 35 parts, and preferably 3 to 20 parts. Is more preferable.

  In the inkjet recording sheet of the present invention, examples of the method for incorporating the gelling agent represented by the general formulas (1) and (2) into the inkjet recording sheet include, for example, the general formulas (1) and ( 2) A method of coating the ink receiving layer containing the gelling agent of the present invention represented by the above or a gel represented by the general formulas (1) and (2) on the ink receiving layer provided on the support. There is a method of applying, impregnating, or spraying a solution or dispersion containing an agent. As a method for containing the gelling agent represented by the general formulas (1) and (2) in the ink receiving layer, the water dispersion of the gelling agent represented by the general formulas (1) and (2) in the ink receiving layer coating A method of adding a liquid is preferably used.

The dispersion of the gelling agent used can be prepared by a publicly known / public method in the presence of various dispersing agents. The particle size of the gelling agent in the dispersion is preferably 2 μm or less, more preferably 1 μm or less. If the particle size of the gelling agent in the dispersion is larger than 2 μm, the smoothness of the surface of the ink receiving layer may be impaired, and an ink jet recording sheet having a high glossiness may not be produced. In addition, by making the dispersed particle diameter of the gelling agent smaller, it is possible to increase the chance of contact with the ink solvent and increase the gelation efficiency.
In the present invention, two or more kinds of gelling agent dispersions may be simultaneously added to the ink receiving layer coating material.

  Oils or aqueous liquid inks are usually used as inks for forming recorded images in the ink jet system, but water-based inks are exclusively used in offices and general homes. A water-based inkjet ink is usually a recording liquid composed of a colorant, a liquid medium (ink solvent), and other additives. Examples of the colorant include various water-soluble dyes such as direct dyes, acid dyes, and reactive dyes, Alternatively, organic / inorganic color pigments are used, and water alone or a mixed solvent of water-water-soluble organic solvent is used as the ink solvent.

Examples of the water-soluble organic solvent used in the inkjet ink include monohydric alcohols such as ethyl alcohol and isopropyl alcohol, polyhydric alcohols such as ethylene glycol diethylene glycol, polyethylene glycol, trimethylolpropane, and glycerin, and triethylene glycol monomethyl ether. , Mono-lower alkyl ethers of polyhydric alcohols such as triethylin, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, and the like. Examples of the alcohol-based water-soluble solvent to be gelled in the present invention include Among water-soluble organic solvents contained in water-based inkjet inks, polyhydric alcohol-based water-soluble solvents are particularly important, such as ethylene glycol, Ethylene glycol, triethylene glycol, and glycols such as polyethylene glycol, mono-lower alkyl ether derivatives of these glycols, and glycerin, be trimethylolpropane is gelled is important. These polyhydric alcohols are used to prevent clogging of inkjet nozzles and kogation.

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.
The ink jet recording sheet of the present invention is not particularly limited in its aspect other than containing the gelling agent represented by the general formulas (1) and (2).

The inkjet recording sheet of the present invention is produced by using a base material with low water permeability, such as a coated paper or a high-quality paper, bonded with a plastic film via an adhesive, or a plastic film or sheet, a synthetic paper, or a paper core. A water-resistant substrate such as a laminated paper whose surface is covered with plastic can be suitably used.
In recent years, in order to give the inkjet recording sheet of the present invention image quality and gloss comparable to silver salt photographs, which have been increasing in demand, as a base material, a water-resistant base material, in particular, both sides of the base paper are made of polyethylene or the like. So-called RC paper laminated with a polyolefin resin is particularly preferably used.

  In the ink jet recording sheet of the present invention, for example, the ink jet recording sheet of the present invention contains the gelling agent of the present invention represented by the general formulas (1) and (2), and is a group as exemplified above. In the case of comprising a support made of a material and an ink receiving layer containing inorganic fine particles and an aqueous polymer binder on the surface thereof, the ink receiving layer does not necessarily need to be a single layer, In addition, a gloss developing layer can be provided for the purpose of imparting and developing gloss to the upper layer above the ink receiving layer.

The coating amount of each layer after drying can be arbitrarily set within a range not impairing the performance as an inkjet recording sheet. In the case of an ink receiving layer, the total coating amount of each layer is 2 to 50 g / In the case of about m ² and a glossy layer, it is preferably about 0.2 to 30 g / m ² . Incidentally, if the total coating amount of each layer of the ink receiving layer is less than 2 g / m ² , not only the recording image quality and the coating film strength may be inferior, but also the fixing property of the ink (dye) may not remain. On the other hand, if it is attempted to increase the coating amount beyond 50 g / m ² , the ink receiving layer is likely to crack, and the recording image quality may be drastically deteriorated.
Similarly, when the coating amount of the glossy layer is less than 0.2 g / m ² , the glossiness may be impaired, and light interference fringes due to the Newton effect are likely to occur, resulting in a recorded image quality. May deteriorate. (Note that if the coating amount exceeds 30 g / m ² , the ink absorptivity may be remarkably deteriorated.)

In the present invention, the ink receiving layer contains inorganic fine particles having an average primary particle diameter of 50 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 the inorganic fine particle material contained in the ink receiving layer include zeolite, light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium oxide, zinc oxide, zinc sulfide, and carbonic acid. Examples include zinc, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, silica, aluminum hydroxide, alumina, alumina hydrate, aluminosilicate, boehmite, and pseudoboehmite. In particular, silica, alumina, alumina hydrate and aluminosilicate are preferable, and silica is particularly preferable.

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 by the BET method, it is preferably about 1000 m ² / g or less. More preferably, it is 200-400 m < ² > / g.
The BET method referred to in the present invention is one of powder surface 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 amount of inorganic fine particles used in the ink receiving layer is preferably about 20 to 90% by mass, more preferably about 30 to 80% by mass, based on the solid content of the ink receiving layer. In this range, there is no possibility that the coating strength of the ink receiving layer is lowered, the ink absorbability and the ink drying property are excellent, and a higher image quality is obtained.

  In the present invention, 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. Synthetic silica is broadly classified into vapor-phase silica and wet silica. In the present invention, gas phase method silica and two kinds of wet method silica described later are preferably used from the viewpoint of obtaining high ink absorbability, transparency, and gloss.

As wet method silica, silica by precipitation method and silica by gel method are well known. These silicas are bonded to primary particles to form secondary particles, and since there are many voids between the primary particles and between the secondary particles, the ink absorption is large and light is scattered. Has a feature that a high print density can be obtained.
Precipitated silica is produced, for example, by adding a mineral acid stepwise to an alkali silicate aqueous solution and filtering the precipitated silica as disclosed in JP-A-55-116613. The gel method silica is obtained by mixing a mineral acid with an alkali silicate solution, gelling in an acidic region, washing and pulverizing.

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

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

On the other hand, JP-wet process fine silica described in 2001-354408 Patent Publication, "a specific surface area of 300m ² / g~1000m ² / g by the BET method, a pore volume of 0.4ml / g~2.0ml / g is a liquid in which silica fine particles are dispersed in a colloidal form, and after adding alkali to the seed liquid, a feed liquid composed of at least one selected from an aqueous solution of active silicic acid and alkoxysilane is added to the seed liquid. It was added in small portions and wherein the growing the silica fine particles, BET method by a specific surface area of 100m ² / g~400m ² / g, average secondary particle diameter of 20nm~300nm and pore volume, is 0.5ml preparation of the silica fine particle dispersion silica fine particles are dispersed in colloidal /g~2.0ml/g method ", or" BET specific surface area is 300 meters ² In g~1000m ² / g, a liquid silica fine pore volume is 0.4ml / g~2.0ml / g is dispersed colloidally with a seed liquid, active silicic acid solution and alkoxy to the seed solution A ratio according to the BET method, wherein a mixture of at least one kind selected from silane and a mixture of alkali is added little by little, or silica fine particles are grown by simultaneously adding the feed liquid and alkali little by little. surface area of 100m ² / g~400m ² / g, average secondary particle diameter of 20 nm to 300 nm, and the silica fine particle dispersion pore volume silica fine 0.5ml / g~2.0ml / g is dispersed colloidally Silica fine particles obtained by the “liquid production method”.

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

  The wet method fine silica disclosed in Japanese Patent Application Laid-Open Nos. 2001-354408 and 2002-145609 is a silica having both the advantages of precipitated silica and gel method silica and the advantages of colloidal silica. This silica, for example, has a secondary particle structure formed by combining primary particles of silica such as the above-mentioned colloidal silica, so that the pore diameter and pore volume can be adjusted, and the secondary particle diameter can be adjusted. Since it has the characteristics that it is relatively easy to adjust to the wavelength of light or less and an ink receiving layer excellent in ink absorbability and glossiness can be easily produced, it is preferably used in the present invention. Hereinafter, these wet process fine silicas are referred to as secondary fine silicas.

Among these, in particular, the secondary fine silica obtained by the condensation method disclosed in JP-A-2001-354408 has the above-described average secondary particle diameter (20 nm to 300 nm) and pore volume without using mechanical means. Since secondary fine silica having (0.5 ml / g to 2.0 ml / g) can be directly produced and the particle size distribution is narrow, the transparency and gloss of the resulting ink-receiving layer are good and preferably used in the present invention. be able to.
In the condensation method disclosed in Japanese Patent Application Laid-Open No. 2001-354408, as the active silicic acid, for example, an alkali metal silicate aqueous solution having a pH of 4 or less obtained by ion exchange treatment with a hydrogen cation exchange resin is used. A silicic acid aqueous solution (active silicic acid aqueous solution) is preferably used.
The active silicic acid aqueous solution is preferably 1 to 6% by mass as SiO ₂ concentration, more preferably 2
It is desirable that it is ˜5 mass% and has a pH of 2 to 4.
Further, the alkali metal silicate may be a commercially available industrial product, more preferably sodium water having a molar ratio of SiO ₂ / M ₂ O (where M represents an alkali metal atom) of about 2 to 4. It is preferable to use glass.

Furthermore, as a method for condensing active silicic acid, the above-mentioned active silicic acid aqueous solution is dropped into hot water, or the active silicic acid aqueous solution is heated to produce seed particles, and the dispersion is gelated before precipitation occurs. the seed particles are stabilized by adding an alkali before, then the preferred in terms of SiO ₂ with respect to SiO ₂ 1 mole contained in the seed particles of the active silicic acid solution while maintaining the stable state from 0.001 to 0 It is preferable to add the seed particles at a rate of 2 mol / min to grow the primary particles of the seed particles.

Further, the wet process fine silica preferably has a specific surface area of 100 to 400 m ² / g by BET method and a pore volume of 0.5 to 2.0 ml / g. Fine silica in this range has a very good balance of cracks in the ink receiving layer, ink absorbency, and gloss.
Among the wet method silicas, the above-mentioned gel method silica and the secondary fine silica obtained by the condensation method disclosed in JP-A-2001-354408 are advantageous for suppressing discoloration and blurring of recorded matter under high temperature and high humidity. Therefore, it is preferably contained in at least one of the ink receiving layers closer to the support of the ink jet recording sheet of the present invention.

The reason why these silicas are more advantageous than silicas produced by other methods for suppressing discoloration and blurring of recorded materials under high temperature and high humidity is not necessarily clear, but they are formed between the primary particles of these silicas. This is thought to be because the pores formed are small, and the movement of the dye and ink solvent that has penetrated into the pores is restricted.
Further, in the ink jet recording sheet of the present invention, the gelling agent represented by the general formulas (1) and (2) is contained in the ink receiving layer containing the wet process silica, whereby the recorded matter at high temperature and high humidity. It is possible to make the discoloration / bleeding suppressing action of the film even more effective.

Vapor phase silica is also called a dry method as opposed to a wet method, and is made by a flame hydrolysis method. Specifically, it is made by burning silicon tetrachloride with hydrogen and oxygen. In place of silicon tetrachloride, silanes such as methyltrichlorosilane and trichlorosilane may be used alone or mixed with silicon tetrachloride. Vapor phase method silica is commercially available as a powder having a very low bulk density.
When the aqueous dispersion of vapor phase silica is dried, it becomes porous silica gel, and the pore volume of the gel by the BET method is generally 1.2 to 1.6 ml / g. This pore volume is convenient for absorbing ink. However, cracks tend to occur during drying, and it is not easy to produce an ink receiving layer free of cracks.

  In the ink jet recording sheet of the present invention, a silica-cationic compound aggregate obtained by premixing and aggregating the above-described silica and a cationic compound is preferably used in at least one of the ink receiving layers. Further, silica-cationic compound aggregated fine particles obtained by pulverizing the aggregated particles to an average particle size of 0.7 μm or less are more preferably used. By using the silica-cationic compound aggregate fine particles, the ink receiving layer can be made into a porous layer having excellent transparency, ink absorbability, ink coloring property, weather resistance and the like.

  The silica-cationic compound aggregated fine particles are preferably colloidal particles composed of secondary particles substantially formed by agglomerating primary particles, and are usually used in the form of an aqueous dispersion (slurry). Is done. When the ink receiving layer is formed using only a silica sol in which the primary particles are monodispersed (for example, commercially available general colloidal silica), the resulting porous layer has a relatively dense structure and ink absorbability. In order to avoid this, it is necessary to increase the thickness of the ink receiving layer, but by doing so, it becomes difficult to avoid the decrease in transparency of the ink receiving layer and the occurrence of cracks. At the same time, there is a problem that the step of coating the ink receiving layer has to be complicated. Of course, there is no problem even if the primary particles are partially contained in the colloidal particle dispersion of the silica-cationic compound aggregates composed of secondary particles.

In addition, the above-mentioned silica-cationic compound aggregate fine particles generally have a breaking d.
It is prepared by a method called an own method (a method of subdividing a bulk material). That is, the silica-cationic compound aggregate fine particles are obtained by pulverizing and subdividing the aggregate obtained by mixing silica and a cationic compound in advance by applying a powerful force using mechanical means. General examples of mechanical means include ultrasonic waves, a high-speed rotating mill, a roller mill, a container drive medium mill, a medium agitation mill, a jet mill, a disintegrator, and a sand grinder.

  In the inkjet recording sheet of the present invention, the average particle diameter of the silica-cationic compound aggregate fine particles (substantially secondary particles) used to form at least one of the ink receiving layers is 0.7 μm or less, The thickness is preferably adjusted to 10 to 300 nm, more preferably 20 to 200 nm. When silica-cationic compound aggregate fine particles having an average particle diameter exceeding 0.7 μm are used, the transparency of the ink receiving layer is remarkably impaired, the print density is extremely lowered, and high gloss is exhibited in the print area. There is no fear. On the other hand, if silica-cationic compound aggregate fine particles having an extremely small average particle diameter are used, there is a concern that a sufficient ink absorption rate cannot be obtained.

  In the ink jet recording sheet of the present invention, the silica used as the substrate of the silica-cationic compound aggregate fine particles used for forming at least one of the ink receiving layers has an average primary particle diameter of 3 nm to 40 nm. Is preferred. When the average primary particle diameter of the silica serving as the substrate is less than 3 nm, the voids between the primary particles become extremely small, and the ability to absorb ink and the solvent in the ink may be significantly reduced. On the other hand, if the average primary particle diameter exceeds 40 nm, the aggregated secondary particles become too large, and the transparency of the ink receiving layer may be lowered.

  In the ink jet recording sheet of the present invention, various cationic compounds are used for the preparation of silica-cationic compound aggregated fine particles used for forming at least one layer of the ink receiving layer. However, various known cationic compounds that are generally used in the production of ink jet recording paper can be used. For example, a primary amine type cationic polymer having a primary amine salt as a constituent unit, such as a 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 chloride, ( Consists of quaternary ammonium salts such as (meth) acryloyloxyethyltrimethylammonium chloride, (meth) acrylamidopropyltrimethylammonium chloride, dimethylamine / epichlorohydrin polycondensate Other quaternary ammonium type cationic polymers having, as a basic poly aluminum chloride, and aluminum compounds such as basic polyaluminum fatty aluminum, zirconyl chloride, basic zirconyl chloride, etc. zirconyl compounds such as fatty acid zirconyl is preferably used.

  Of the various known cationic compounds, a primary amine type cationic polymer having a primary amine salt as a structural unit is preferably used for the ink jet recording sheet of the present invention, among which N-vinylacrylamidine salt and monoallylamine are used. A primary amine type cationic polymer having a primary amine salt selected from salts as a structural unit is more preferably used.

（式中、Ｘは酸残基を示す。）
で表されるを構成単位を含むカチオンポリマー（Ａ）、あるいはモノアリルアミン塩型の１級アミン型カチオンポリマーして下記一般式（４）又は（５）：

（式中、Ｙは酸残基を示す。）
で表される少なくとも１種の構成単位（ｂ１）と、下記一般式（６）：
（式中、Ｒ⁷は炭素数１〜１８のアルキル基、炭素数１〜１８のアルコキシキル基、炭素
数６〜１２のアリール基、又はベンジル基を示す。）

で表される少なくとも１種の構成単位（ｂ２）とを含むカチオンポリマー（Ｂ）が本発明のインクジェット記録シートには好ましく用いられる。 In particular, as a primary amine type cationic polymer of N-vinylacrylamidine salt type, the following general formula (3):

(In the formula, X represents an acid residue.)
The following general formula (4) or (5): a cationic polymer (A) containing a structural unit, or a monoallylamine salt type primary amine type cationic polymer.

(In the formula, Y represents an acid residue.)
At least one structural unit (b1) represented by the following general formula (6):
(In the formula, R ⁷ represents an alkyl group having 1 to 18 carbon atoms, an alkoxyalkyl group having 1 to 18 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a benzyl group.)

A cationic polymer (B) containing at least one structural unit (b2) represented by the formula (1) is preferably used in the inkjet recording sheet of the invention.

In general formula (3), X ⁻ represents an acid residue, for example, a chlorine ion, a bromine ion, or the like. In general formula (6), R ⁹ 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 include methyl, ethyl, n-propyl, i-propyl, butyl, pentyl, hexyl, octyl, nonyl, decyl, dodecyl, octadecyl and the like. 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 excellent in suppressing discoloration and blurring of a recorded image under high temperature and high humidity.

In the cationic polymer (B), 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. is there. In the cationic polymer (B), by setting the molar ratio of the structural unit (b1) to the structural unit (b2) within this range, the coating stability is excellent, and particularly, the jet is excellent in high image quality and long-term storage stability. A recording sheet is obtained.

In addition to the above-described inorganic fine particles having an average primary particle diameter of 30 nm or less, the cationic polymer (A) containing the structural unit of the general formula (3) and / or at least one kind represented by the general formula (4) or (5) By containing the cationic polymer (B) containing the structural unit (b1) and the structural unit represented by the general formula (6), it is possible to obtain a coating liquid for an ink receiving layer having excellent paint stability. The ink-receiving layer obtained by applying the coating liquid has almost no cracks, is excellent in glossiness, ink absorption, and ink drying properties, and is excellent in the image quality of images recorded by an ink jet printer and its long-term storage stability. Therefore, it can be suitably used in the present invention.

When a cationic polymer is used in the present invention, the molecular weight is preferably about 5,000 to 1,000,000, more preferably about 10,000 to 200,000.
Two or more kinds of the known cationic compounds can be used simultaneously for the preparation of silica-cationic compound aggregate fine particles.

  When the ink jet recording sheet of the present invention comprises a support and an ink receiving layer containing inorganic fine particles and an aqueous polymer binder on the surface thereof, the aqueous polymer binder used in the ink receiving layer includes For example, starch derivatives such as oxidized starch and etherified starch, cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, proteins such as casein, gelatin and soy protein, completely (partially) saponified polyvinyl alcohol, Polyvinyl alcohols such as silicon-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol and cation-modified polyvinyl alcohol, styrene-butadiene latex, acrylic latex, polyester latex, polyurethane latex Synthetic latex such as a vinyl acetate-based latex, other such, polyvinylpyrrolidone, styrene - salts of maleic anhydride copolymers, and the like can be used.

  Among these aqueous binders, polyvinyl alcohols such as completely (partially) saponified polyvinyl alcohol, silicon-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, and cation-modified polyvinyl alcohol, or polyurethane latex are more preferably used.

In the present invention, when polyvinyl alcohols are used, among the polyvinyl alcohols, partially saponified polyvinyl alcohol having a saponification degree of 80% or more, fully saponified polyvinyl alcohol, or silicon-modified polyvinyl alcohol is preferable. Is preferably 200 to 5,000, more preferably 500 to 5,000.
Polyvinyl alcohol is preferable because it has high transparency and water resistance among water-based binders, is nonionic, can be mixed with various materials, and has a relatively low swellability around 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.

The reason why partially saponified polyvinyl alcohol having a saponification degree of 80% or more or completely saponified polyvinyl alcohol is preferable is that it is excellent in water resistance, and silicon-modified polyvinyl alcohol is preferable because of its high water resistance and inorganic pigment. Good adhesion to fine particles.
The reason why the average degree of polymerization of partially saponified polyvinyl alcohol having a saponification degree of 80% or more, fully saponified polyvinyl alcohol, or silicon-modified polyvinyl alcohol is preferable among the polyvinyl alcohols is that the degree of polymerization in this range. This is because when a product is used, the viscosity is excellent in water resistance and easy to handle.

The polyurethane latex is preferably a self-emulsifying cationic polyurethane latex having a primary to quaternary ammonium base in the main chain or side chain.
These aqueous polymer binders are generally used in an amount of about 1 to 100 parts by mass, preferably about 5 to 50 parts by mass with respect to 100 parts by mass of the inorganic fine particles.

  In the present invention, a crosslinking agent can be used together with the aqueous polymer binder. The crosslinking agent is not particularly limited, but specific examples include boric acid, borax, borate, glyoxal, melamine / formaldehyde, glutaraldehyde, methylol urea, polyisocyanate compound, epoxy compound, aziridine compound, carbodiimide compound, dihydrazide Examples thereof include a compound and a zirconium compound. Among these, boric acid, borax, or borate is preferable.

In the present invention, it is also possible to use a phosphorus oxoacid salt as a stabilizer for the coating material forming the ink receiving layer. As the stabilizer, there is no particular limitation on the phosphorus oxoacid salt. Specific examples thereof include phosphoric acid, phosphorous acid, hypophosphorous acid, metaphosphoric acid, metaphosphorous acid, pyrophosphoric acid, pyrophosphorous acid. And alkali metal salts such as polyphosphoric acid, alkaline earth metal salts, ammonium salts, and zinc salts.
Among these, hypophosphite is preferably used because it is particularly effective in coating stability. Specific examples of hypophosphites include sodium hypophosphite, potassium hypophosphite, calcium hypophosphite, magnesium hypophosphite, barium hypophosphite, ammonium hypophosphite, zinc hypophosphite In particular, sodium hypophosphite is most preferably used because it has the highest effect on paint stability.

  Further, when the ink jet recording sheet of the present invention has an ink receiving layer, various known pigment dispersants, thickeners, fluidity modifiers, antifoaming agents, antifoaming agents, release agents are contained in the ink receiving layer. Molding agents, foaming agents, penetrants, coloring dyes, coloring pigments, fluorescent brighteners, preservatives, antibacterial agents, water resistance agents, image stabilizers, and the like can be added as appropriate.

When the ink jet recording sheet of the present invention has an ink receiving layer, the ink receiving layer is formed by coating the ink receiving layer with a coating method such as a bar coater, a blade coater, an air knife coater, a gravure coater, a die coater, or a curtain coater. It is formed by coating and drying on at least one side of the support so that the coating amount after drying is about ² to 50 g / m ² . Incidentally, when the coating amount is within this range, the recording image quality and the coating film strength are excellent.
For the purpose of imparting high gloss after the ink receiving layer is formed, for example, it is possible to impart surface smoothness through the roll nip under pressure with a super calender, gloss calender, or the like.

When the inkjet recording sheet of the present invention comprises a support and a plurality of ink receiving layers, an aqueous solution containing a cationic polymer is applied to at least one ink receiving layer (inner ink receiving layer) formed on the support. After that, it is preferable to form an at least one other ink receiving layer (outer ink receiving layer) by coating the ink receiving layer coating liquid thereon.
The cationic polymer contained in the aqueous solution to be applied to the inner ink receiving layer is not particularly limited, and various cationic polymers as described above can be used, but allylamine salt homopolymer, allylamine salt-diallylallylamine salt copolymer, cationic polymer (B ), And the like, monoallylamine salt type primary amine type cationic polymers are preferably used.
In this method, when the ink jet recording sheet of the present invention containing the gelling agent represented by the general formulas (1) and (2) is composed of a support and a plurality of ink receiving layers, the recorded image is subjected to high temperature and high humidity. It is effective for further suppressing the discoloration / bleeding in the ink, and also has a high effect of suppressing cracking of the outer ink receiving layer, and is effective for imparting an excellent appearance to the ink jet recording sheet of the present invention. is there.

When the ink jet recording sheet of the present invention comprises a support and a plurality of ink receiving layers, the use of a crosslinking agent in an aqueous solution containing various cationic polymers suppresses cracking of the outer ink receiving layer. It is more preferable from the viewpoint of.
In the case where the inkjet recording sheet of the present invention comprises a support and a plurality of ink receiving layers, in order to effectively suppress cracking of the outer ink receiving layer using an aqueous solution containing various cationic polymers in combination with a crosslinking agent. the, preferably 0.01 to 1.0 g / m ² as coated amount of crosslinking agent, 0.05 to 0.5 g / m ² is more preferable. If it is less than 0.01 g / m ² , the effect of suppressing cracking is low, and if it exceeds 1.0 g / m ² , the ink receiving layer may be cracked due to strong shrinkage during drying or ink absorbability may be reduced. .
Moreover, as mass ratio of the crosslinking agent and various cationic polymers in the aqueous solution containing the various cationic polymers used together with the crosslinking agent, 1: 1 to 1:20 is preferable, and 1: 1 to 1:10 is more preferable. . By making the mass ratio of the cross-linking agent and various cationic polymers within this range, cracking of the outer ink-receiving layer is suppressed, and a glossy appearance and suppression of discoloration and bleeding of the recorded image under high temperature and high humidity are suppressed. The ability to be more sure can be imparted to the ink jet recording sheet of the present invention.

Specific examples of the crosslinking agent that can be used together in an aqueous solution containing various cationic polymers include, for example, boron compounds such as boric acid, borax, and borate, glyoxal, melamine / formaldehyde, glutaraldehyde, methylol urea, polyisocyanate. Examples thereof include compounds, epoxy compounds, aziridine compounds, carbodiimide compounds, dihydrazide compounds, aluminum compounds, zirconium compounds and the like. Of these, boron compounds are preferable, and borax is particularly preferable.
When borax is mixed with an aqueous solution containing various cationic polymers, the effect of suppressing cracking of the outer ink receiving layer is high. Further, when this mixed aqueous solution of various cationic polymers and borax is used after adjusting to pH 7.0 to 10.0, preferably pH 7.5 to 9.0 with an alkali such as sodium hydroxide, the outer ink is used. This is preferable because it is more effective in suppressing cracking of the receiving layer.

  Further, an inkjet recording sheet having a higher surface glossiness can be obtained by providing a glossy expression layer above the ink receiving layer of the ink jet recording sheet of the present invention and casting, or by directly casting the ink receiving layer itself. Can also be produced. This gloss-expressing layer contains a resin or a pigment and a resin, and is porous or liquid-permeable so long as the gloss does not decrease so that the ink can be absorbed and passed quickly and does not hinder the absorption in the ink receiving layer. It is preferable to make it. For that purpose, the gloss developing layer is formed by selecting a drying condition that does not completely form the resin blended in the gloss developing layer by adding a pigment to the gloss developing layer within a range not deteriorating the gloss. Is preferred.

  Examples of the pigment used for the glossy layer include the same pigments as those used for the ink receiving layer, but in terms of gloss, transparency and ink absorbability, colloidal silica, amorphous silica, aluminum oxide, aluminosilicate, Zeolite, synthetic smectite and the like are preferable. These pigments are desirably contained in the glossy layer in an amount of 10 to 95% 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 within this range, excellent ink absorbability, glossiness, and printing density can be obtained.

Examples of the resin used for the glossy layer include water-soluble binders (for example, polyvinyl alcohols such as polyvinyl alcohol, cation-modified polyvinyl alcohol, silyl-modified polyvinyl alcohol, casein, soy protein, synthetic proteins, starch, carboxymethyl cellulose, methyl cellulose, etc. Cellulose derivatives), styrene-butadiene copolymers, conjugated diene polymer latexes such as methyl methacrylate-butadiene copolymers, water-dispersible resins such as vinyl copolymer latexes such as styrene-vinyl acetate copolymers, In addition, various publicly known resins (adhesives) such as water-based acrylic resins, water-based polyurethane resins, and water-based polyester resins can be exemplified, and these can be used alone or in combination of two or more.

  In the case of forming a glossy expression layer mainly composed of a resin, a polymer or copolymer (hereinafter collectively referred to as a polymer) obtained by polymerizing a monomer having an ethylenically unsaturated bond (hereinafter referred to as an ethylenic monomer). Resin), and a substituted derivative 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 the polymer is colloidal silica such as SiOH group and the like. A functional group capable of reacting may be introduced and used in the form of a composite by reacting with colloidal silica. When this composite is used, it tends to be excellent in gloss and ink absorbability.

  When forming a glossy expression layer by a casting method, the glass transition point of the resin is preferably −25 ° C. or higher, more preferably −20 to 100 ° C. If the glass transition point is too low, the film formation proceeds too much during drying, resulting in a risk of decreasing the ink absorption rate, but conversely, if the glass transition point is too high, A large number of unintentional cracks are generated, and not only the surface gloss is lowered, but also the ink absorption is made non-uniform, and as a result, the recording image quality may be lowered. In addition, when forming a glossy layer by the cast method, the processing / drying temperature is also important, and if the processing / drying temperature is too high, the film formation proceeds too much and the surface porosity decreases, resulting in a decrease in the ink absorption rate. Conversely, if the drying temperature is too low, the gloss tends to be poor, and the productivity also decreases.

  As a method for forming a glossy expression layer by a casting method, there are a wet casting method, a gelation casting method, and a rewet casting method. In the wet method, while the gloss developing layer coated on the base paper is in a wet state, the gloss developing layer is pressed against the heated mirror drum surface to perform a high gloss finish. In the gelation method, while the glossy layer coated on the base paper is in a wet state, the glossy layer is brought into contact with the gelling solution, and the gelled glossy layer is pressed against the surface of the heating drum to be strong. Glossy finish. In the rewet method, the wet glossy layer is once dried and then brought into contact with the wetting liquid again, and then pressed against the surface of the heating drum to perform a high gloss finish.

It is also possible to add a cationic compound to the glossy layer in order to increase the printing density, improve the water resistance, or add various auxiliaries to improve the light resistance and gas resistance.
The coating amount of the glossy layer is preferably 0.2 to 30 g / m ² on a dry solids, more preferably from 0.5 to 20 g / m ^2. When the dry solid content is within this range, the gloss, ink drying property and recording density are excellent.

  In addition, the ink jet recording sheet of the present invention may be formed by coating the ink receiving layer in multiple layers, providing an intermediate layer between the support and the ink receiving layer, or providing a protective layer on the back surface of the support, It is also possible to perform adhesive processing on the back surface of the support, and various known techniques in the field of ink jet recording sheet production can be added.

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

[Synthesis of gelling agent (G)]
Although the synthesis example of the gelatinizer (G) of this invention is shown below, a synthesis example is not limited to these. The gelling agent (G) of the present invention can have a variety of compositions depending on the combination of a long-chain amine and an amino acid that are starting materials.

Synthesis of gelling agent G-1 (N-benzyloxycarbonyl-L-valine octadecylamide) Eiji Kenji, Shirai Yasuyoshi, Surface, 36 (6), 291-303 (1998) (Non-patent Document 2), K. With reference to Hanabusa et.al., Chem. Mater., 11 (3), 649-655 (1999) (Non-patent Document 7) and the like, the gelling agent [G-1: N-benzyloxycarbonyl-L- Valine octadecylamide, the following structural formula (7)] was synthesized. That is, by applying the Schottten-Baumann method, 1 g of 10 g (40 mmol) of N-benzyloxycarbonyl-L-valine obtained from 5.9 g (50 mmol) of L-valine and 9.4 g (55 mmol) of benzyl chloroformate is obtained. And dissolved in 300 ml of dehydrated ethyl acetate, 9.1 g (44 mmol) of DCC (N, N′-dicyclohexylcarbodiimide) was added and stirred at 0 ° C. for 1 hour, and then 11.9 g of stearylamine ( 44 mmol) was added, and the mixture was stirred at 0 ° C. for 1 hour, further at room temperature for 12 hours, and at 45 ° C. for 10 hours. Since the by-produced dicyclohexylurea was filtered off and the filtrate was allowed to stand at room temperature, the target N-benzyloxycarbonyl-L-valine octadecylamide (gelator: G-1) was precipitated as a slightly oily solid. This was filtered off and dried. The yield was 14.9 g (29.6 mmol).

The obtained gelling agent G-1 is a compound in which R ¹ = benzyl group, n = 1, R ² = iso-propylmethylene group, m = 0, R ⁴ = octadecyl group in the general formula (1) It corresponds to.

(Production and performance evaluation of inkjet recording sheet)
Preparation of inkjet recording sheet:
The ink jet recording sheet of the present invention containing the gelling agent (G-1) was prepared by the method described in the examples below. However, the preparation method is not limited, and a known publicly used technique may be used. Can be made by arranging.
(Performance evaluation of the prepared inkjet recording sheet)
Outputs are set to 100% for each of C and M, 100% for each of C and Y, and 100% for each of M and Y using the Canon inkjet printer PIXUS 850i on the inkjet recording sheets produced in the examples and comparative examples. In addition, printing is performed so that three circular figures with a radius of 30 mm are arranged so as to overlap each other by 15 mm, and an ISO-400 image ("" using an Epson inkjet printer PM-970C and a Canon inkjet printer PIXUS 9900i). High-definition color digital standard image data ISO / JIS-SCID ", p13, image name: portrait, issued by the Japan Planning Association), solid print image with Bk = 100% output setting, solid print of composite black Print images and record each image Of Ink absorbency] were evaluated by the following methods of [optical density], and [heat moisture].

(Ink absorption)
The level of sharpness of the boundary part of each of the three circles set to 100% for C and M, 100% for C and Y, and 100% for each of M and Y was visually observed and evaluated.
A: The boundary portion is clear and the ink absorbability is very good. ○: The boundary portion is slightly lacking in sharpness, but there is no problem in practical ink absorption. Δ: Bleeding is observed in the boundary portion. ： Slightly inferior in ink absorbency and a level of concern for practical use ×: Bleeding was observed at the boundary part, and beading was also noticeable and practically problematic

(Optical density)
An image printed with an Epson inkjet printer PM-970C with a Bk = 100% output setting was measured with a Macbeth reflection densitometer RD-19I, and the optical density was compared and evaluated. (Evaluation criteria)
The higher the optical density, the better. If OD> 2.25, it is advantageously used practically.
(Heat and humidity resistance)
The obtained ISO-400 image, a solid print image with an output setting of Bk = 100%, and a composite black solid print image are put in a pocket album immediately after printing, and placed in a constant temperature and humidity chamber at 30 ° C. and a relative humidity of 80%. After storage for 7 days, the level of heat and humidity resistance was visually observed and evaluated.
(Evaluation criteria)
A: Occurrence of blemishes and discoloration were hardly observed, and the print quality before processing was maintained. B: Slight blemishes and slight discoloration were observed, but there was no problem in practical use. △: Blemish and discoloration were easily recognized and had a practically problematic level. ×: Brightness was observed and extremely severe discoloration occurred, indicating a practically problematic level. The

Example 1
[Preparation of aqueous dispersion of gelling agent (G-1)]
Add 11 parts of the gelling agent (G-1) prepared in the above synthesis example and 0.5 part of styrene-maleic anhydride dispersant to 100 parts of water, and disperse with a paint shaker together with glass beads with a diameter of 1 mm. Then, a 10% aqueous dispersion (average dispersion diameter: 1.0 μm) of the gelling agent (G-1) was prepared.
(Adjustment of coating liquid A for inner ink receiving layer)
5% of 20% dispersion of amorphous silica synthesized by wet gel method (trade name: Silojet 703A, manufactured by Grace Devison) 500 parts, polyvinyl alcohol [trade name: PVA-145, manufactured by Kuraray Co., Ltd.] 400 parts of an aqueous solution, 55 parts of a 10% aqueous dispersion of a gelling agent (G-1), and a small amount of an antifoaming agent, a dispersing agent (please write specific details if possible. The same applies hereinafter) and water. A coating liquid A for an inner ink receiving layer having a solid content concentration of 15% was obtained.

(Preparation of coating liquid B for outer ink receiving layer)
Gas phase method silica [trade name: Aerosil 300, average particle size of primary particles: 7 nm, specific surface area by BET method: 300 m ² / g, manufactured by Nippon Aerosil Kogyo Co., Ltd.] 100 parts, N-vinylacrylamidine hydrochloride-acrylamide After adding 40 parts of a 20% aqueous solution of a copolymer (molar ratio 2: 1, molecular weight about 20,000) and 750 parts of ion-exchanged water, the mixture was dispersed with a stirrer, and then processed using a wet ultrafine atomizer Nanomizer. Next, 360 parts of 5% aqueous solution of polyvinyl alcohol [trade name: PVA-145, manufactured by Kuraray Co., Ltd., saponification degree 99%, average polymerization degree 4,500] and a small amount of antifoaming agent, dispersing agent and water were added. An ink receiving layer coating solution B having a solid content concentration of 8% was obtained.

(Creation of inkjet recording sheet)
Coating liquid A for inner ink receiving layer on laminate coated paper (commercially coated paper (trade name: OK coated paper, 127.9 g / m ² , 15 μm polyethylene laminated on both sides of Oji Paper Co., Ltd.)) Is applied with a Mayer bar so as to have a solid content of 20 g / m ^2, and an undercoat layer is provided. Then, after water application, the outer ink receiving layer coating solution B is adjusted to a solid content of 8 g / m ^2. The ink receiving layer was provided by applying and drying with a Mayer bar to prepare an ink jet recording sheet.

Example 2
(Preparation of paint C for glossy layer)
Add a small amount of antifoaming agent, dispersant and water to 100 parts of colloidal silica (trade name: Snowtex OL, manufactured by Nissan Chemical Co., Ltd.) and 3 parts of ammonium stearate, and a coating solution for glossy expression layer with a solid content of 8%. C was obtained.
(Creation of inkjet recording sheet)
On the outer ink receiving layer formed by the method of Example 1, the gloss developing layer coating liquid C was applied, and while it was in a wet state, linear pressure was applied to the mirror-plated mirror drum with a surface temperature of 100 ° C. An ink jet recording sheet was obtained by pressure contact at 2000 N / cm to form a glossy layer.

Example 3
(Preparation of coating liquid D for outer ink receiving layer)
Gas phase method silica [trade name: Aerosil 300, average particle size of primary particles 7 nm, specific surface area 300 m ² / g by BET method, manufactured by Nippon Aerosil Kogyo Co., Ltd.] 100 parts, 20 mol% methoxycarbonyl-modified polyallylamine hydrochloride After adding 40 parts of a 20% aqueous solution of salt (molecular weight of about 15,000) and 750 parts of ion-exchanged water and dispersing with a stirrer, the mixture was processed using a wet ultrafine atomizer Nanomizer. Subsequently, polyvinyl alcohol [trade name: PVA-145, (
Co., Ltd., Kuraray Co., Ltd., saponification degree 99%, average polymerization degree 4,500] 5% aqueous solution 360 parts and a small amount of antifoaming agent, dispersant and water were added, and solid content concentration 8% coating solution for ink receiving layer D was obtained.
(Creation of inkjet recording sheet)
An ink jet recording paper was prepared in the same manner as in Example 2 except that the outer ink receiving layer coating liquid D was used in place of the outer ink receiving layer paint B in Example 2.

Example 4
(Creation of inkjet recording sheet)
In Example 1, the water coating liquid used before forming the outer ink receiving layer was changed from water to a borax / polyallylamine hydrochloride-diallylamine hydrochloride copolymer [trade name: PAA-D41-HCl, manufactured by Nitto Boseki Co., Ltd., The ink receiving layer was formed in the same manner as in Example 1 except that the mixture was changed to a mixed aqueous solution having a molecular weight of about 2,000,000 (1: 4 mixed solution, concentration 4%). An ink jet recording sheet having a glossy layer applied thereon was obtained in the same manner as in Example 2.

Example 5
(Preparation of secondary fine silica)
Sodium silicate solution having a SiO ₂ concentration of 30% by mass and a SiO ₂ / Na ₂ O molar ratio of 3.1 [Co., Ltd.
Distilled water is added to Tokuyama's No. 3 sodium silicate] to prepare a dilute sodium silicate aqueous solution having a SiO ₂ concentration of 4.0% by mass, and then a hydrogen type cation exchange resin [Diaion manufactured by Mitsubishi Chemical Corporation]. An aqueous active silicic acid solution was prepared through a column packed with [SK-1BH]. A 5 liter glass reaction vessel equipped with a reflux, stirrer, and thermometer was charged with 500 g of distilled water, heated to 100 ° C., and kept at 100 ° C., the active silicic acid aqueous solution prepared earlier was 1.5 g / min. 450 g was added at a rate of 1 to prepare a seed solution. The average secondary particle diameter of the seed particle aggregate in the seed solution was 184 nm. Subsequently, after stabilizing by adding 0.9 g of 28% ammonia aqueous solution, 550 g of active silicic acid aqueous solution was further added at 100 ° C. at a rate of 1.5 g / min. After completion of the addition, the mixture was heated to reflux at 100 ° C. for 9 hours and then concentrated to obtain a 20 mass% secondary fine silica dispersion. The average primary particle size of the silica fine particles 1
The average secondary particle diameter was 1 nm, the specific surface area was 257 m ² / g.

(Preparation of coating liquid E for inner ink receiving layer)
500 parts of a 20% dispersion of amorphous secondary fine silica synthesized by the wet method obtained earlier, 400 parts of a 5% aqueous solution of polyvinyl alcohol (trade name: PVA-145, manufactured by Kuraray Co., Ltd.), the above synthesis 55 parts of the gelling agent (G-1) prepared in the example and a small amount of an antifoaming agent, a dispersing agent and water were added to obtain a coating solution E for an undercoat layer having a solid content concentration of 15%.
(Creation of inkjet recording sheet)
An ink jet recording sheet was prepared in the same manner as in Example 4 except that instead of the inner ink receiving layer coating material A, the inner ink receiving layer coating material E was used.

Examples 6-15
In Example 4, in the same manner as in Example 4, except that the following gelling agent was used instead of the gelling agent (G-1) (N-benzyloxycarbonyl-L-valine octadecylamide). A sheet was produced.
The gelling agents (G-2 to G-11) in the following examples are appropriately selected from various long-chain amines and various amino acids according to the synthesis examples described above, and the reaction conditions are appropriately adjusted. Made. [Gelling agents G-2 to G-5 correspond to the compound of the general formula (1) type, and gelling agents G-6 to G-11 correspond to the compound of the general formula (2) type. ]

Example 6
Gelling agent (G-2): N-benzyloxycarbonyl-L-valinyl-L-valine octadecylamide [in the general formula (1), R ¹ = benzyl group, n = 1, R ² = iso-propylmethylene It corresponds to a compound in which m = 1, R ³ = iso-propylmethylene group, R ⁴ = octadecyl group. ]

Example 7
Gelling agent (G-3): N-benzyloxycarbonyl-L-valinyl-L-valine octylamide [in the above general formula (1), R ¹ = benzyl group, n = 1, R ² = iso-propylmethylene It corresponds to a compound in which m = 1, R ³ = iso-propylmethylene group, R ⁴ = octyl group. ]

Example 8
Gelling agent (G-4): N-benzyloxycarbonyl-L-leucyl-β-alanine octadecylamide [in the general formula (1), R ¹ = benzyl group, n = 1, R ² = iso-butylmethylene Group, m = 1, R ³ = ethylene group, R ⁴ = octadecyl group. ]

Example 9
Gelling agent (G-5): N-benzyloxycarbonyl-L-valinyl-β-alanine octadecylamide [in the general formula (1), R ¹ = benzyl group, n = 1, R ² = iso-propylmethylene Group, m = 1, R ³ = ethylene group, R ⁴ = octadecyl group.

Example 10
Gelling agent (G-6): N, N′-dibenzyloxycarbonyl-L-isoleucine-1,12-dodecanyldiamide [in the general formula (2), R ⁵ = benzyl group, p = 1,
It corresponds to a compound in which R ⁶ = 1-methylpropylmethylene group, q = 0, and R ⁸ = dodecamethylene group. ]

Example 11
Gelling agent (G-7): N, N′-dibenzyloxycarbonyl-L-valine-1,12-dodecanyldiamide [in the general formula (2), R ⁵ = benzyl group, p = 1, R It corresponds to a compound in which ⁶ = iso-propylmethylene group, q = 0, and R ⁸ = dodecamethylene group.
]

Example 12
Gelling agent (G-89: N, N′-diethoxycarbonyl-L-isoleucine-1,12-dodecanyldiamide [in the general formula (2), R ⁵ = ethyl group, p = 1, R ⁶ = It corresponds to a compound in which 1-methylpropylmethylene group, q = 0, R ⁸ = dodecamethylene group.
]

Example 13
Gelling agent (G-9): N, N′-diethoxycarbonyl-L-valine-1,12-dodecanyldiamide [in the general formula (2), R ⁵ = ethyl group, p = 1, R ⁶ = Iso-propylmethylene group, q = 0, R ⁸ = corresponding to a dodecamethylene group. ]

Example 14
Gelling agent (G-10): N, N′-diethoxycarbonyl-L-valine ethylenediamide [in the general formula (2), R ⁵ = ethyl group, p = 1, R ⁶ = iso-propylmethylene group , Q = 0, R ⁸ = corresponding to an ethylene group. ]

Example 15
Gelling agent (G-11): N, N′-dibenzyloxycarbonyl-L-valinyl-L—
Valine-1,20-icosyldiamide [in the general formula (2), R ⁵ = ethyl group, p
= 1, R ⁶ = iso-propylmethylene group, q = 1, R ⁷ = iso-propylmethylene group, and R ⁸ = icosylene group. ]

Comparative Example 1
In Example 1, an inkjet recording sheet was prepared in the same manner as in Example 1 except that the gelling agent (G-1) was not used.

Comparative Example 2
In Example 1, instead of the gelling agent (G-1), N-benzyloxycarbonyloctadecylamine (G-12) having no L-valine moiety was used to prepare an inkjet recording sheet in the same manner as in Example 1. Created.

Comparative Example 3
In Example 1, an inkjet recording sheet was prepared in the same manner as Example 1 using N-benzyloxycarbonyl-β-alanine octadecylamide (G-13) instead of the gelling agent (G-1). .
N-benzyloxycarbonyl-β-alanine octadecylamide (G-13) is represented by the following formula (1): R ¹ = benzyl group, n = 0, m = 1, R ³ = ethylene group, R ⁴
= Octadecyl group can be expressed as a compound, but since n = 0, it is not included in the present invention.
The performance of the inkjet recording sheet produced as described above is summarized in a table.

  As is clear from the table, the ink jet recording sheets (Examples 1 to 15) of the present invention containing the gelling agents (G-1 to G-11) are excellent in ink absorbability and high in recording density. The recorded image is also clear and excellent in long-term storage under high temperature and high humidity. On the other hand, as in Comparative Example 1, there is no problem in ink absorption and recording density unless a gelling agent is used. However, when a recorded image is stored for a long period of time under high temperature and high humidity, blurring and discoloration occur. There is room for improvement. Further, even when a compound such as Comparative Examples 2 and 3 is used, it is not only effective for long-term storage of recorded images under high temperature and high humidity, but also results in significant discoloration.

  The ink jet recording sheet of the present invention not only achieves particularly high ink absorbability, optical density, and image quality comparable to a silver salt photograph, but also has excellent performance (high temperature and high temperature) for long-term storage of recorded images under high temperature and high humidity. There is a tendency to print images taken with a digital camera via a personal computer, further improving the performance of future inkjet printers. As an ink-jet recording sheet that satisfies the advanced characteristics required for the recording medium as it is fixed, it also enables the realization of an ink-jet recording medium that has image quality and storability comparable to silver salt photography. Can be used.

Claims (14)

The following general formulas (1) and (2):

In [Equation (1), the R ¹ is an alkyl group or a benzyl group having 1 to 8 carbon atoms, R ² is a divalent organic group having a side chain, R ³ is a divalent organic group, R ⁴ is the number of carbon atoms Represents an alkyl group of 1 to 22, n represents an integer of 1 to 8, and m represents an integer of 0 to 8.
In Formula (2), R ⁵ is an alkyl group having 1 to 8 carbon atoms or a benzyl group, R ⁶ is a divalent organic group having a side chain, and R ⁷ and R ⁸ are divalent divalent groups. An organic group is represented, p is an integer of 1-8, q shows the integer of 0-8. ]
An ink jet recording sheet having an ink receiving layer containing at least one selected from low molecular weight organic compounds capable of gelling an alcohol-based water-soluble organic solvent represented on the substrate.   The ink jet recording sheet according to claim 1, wherein the support is a water resistant support.   The ink receiving layer is composed of at least two ink receiving layers each containing at least one kind of inorganic fine particles and an aqueous polymer binder, and the ink receiving layer provided immediately above the support is the alcohol-based water-soluble layer. The content of the low molecular weight organic compound, which is an ink receiving layer containing at least one selected from low molecular weight organic compounds capable of gelling a water-soluble organic solvent, and capable of gelling the alcohol-based water-soluble organic solvent The ink jet recording sheet according to claim 1, wherein the content is 1 to 35 parts when the mass part of the inorganic fine particles contained in the ink receiving layer is 100 parts. At least one of the inorganic fine particles contained in the ink receiving layer provided immediately above the support has an average primary particle size of 50 nm or less, an average secondary particle size of 1.0 μm or less, and a BET. 4. The ink jet recording sheet according to claim 3, which is an amorphous anionic silica produced by a wet method and having a specific surface area of 200 m < ² > / g or more.   5. The ink jet recording sheet according to claim 4, wherein at least one of the amorphous anionic silica produced by the wet method is a wet method silica produced by a gel method.   The at least one of the amorphous anionic silicas produced by the wet process is a wet process secondary fine silica produced by condensing activated silicic acid. The inkjet recording sheet as described. Above the ink receiving layer provided immediately above the support, at least one cationic fine pigment selected from silica, aluminosilicate, and alumina having an average primary particle diameter of 3 nm to 50 nm as inorganic fine particles; The ink receiving layer comprising at least one water-soluble polymer and having a function of mainly capturing and fixing a dye in the ink is provided in a layered manner. The inkjet recording sheet as described.   At least one of the cationic fine pigments is a composite fine particle of vapor phase method silica having an average primary particle size of 30 nm or less and a cationic inorganic compound and / or a cationic organic compound. The inkjet recording sheet according to claim 7. At least one of the cationic fine pigments is a vapor-phase process silica having an average primary particle size of 30 nm or less, and the following general formula (3)

(In the formula, X represents an acid residue.)
And a cationic polymer (A) having a weight average molecular weight of 10,000 or more and less than 200,000, and / or the following general formula (4) or (5):

(In the formula, Y represents an acid residue.)
At least one structural unit (b1) represented by the following general formula (6):

(In the formula, R ⁹ represents an alkyl group having 1 to 18 carbon atoms, an alkoxyalkyl group having 1 to 18 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a benzyl group.)
The weight average molecular weight is 10,000 or more and less than 200,000, and the molar ratio of the structural unit b1 to the structural unit b2 is 0.5: 1 to 20: The ink jet recording sheet according to claim 7, wherein the ink jet recording sheet is a composite fine particle with a cationic polymer (B) being 1.   On the at least one ink receiving layer containing the inorganic fine particles and the aqueous polymer binder, an aqueous solution containing a cationic polymer is applied to form a water coating layer, and then the cationic fine pigment and the water-soluble polymer are mixed. The ink jet recording sheet according to claim 3, wherein at least one other ink receiving layer including an ink receiving layer is provided.   The inkjet recording sheet according to claim 10, wherein the aqueous solution containing the cationic polymer further contains a crosslinking agent.   The inkjet recording sheet according to any one of claims 1 to 12, wherein the water-resistant support is a support having both sides of paper coated with a polyolefin resin.   The ink jet recording sheet according to claim 1, wherein the ink jet recording sheet has an ink receiving layer subjected to a cast treatment.   The ink jet recording sheet according to any one of claims 1 to 13, wherein the ink jet recording sheet has a glossy expression layer obtained by performing a casting process on an upper layer than the ink receiving layer.