JP2001301314A - Ink jet recording sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording sheet, with which an ink jet image having an extremely high saturation such as extremely high bleeding resistance with the passage of time, water resistance and lustrous properties, being not dull and more clear and having higher color purity and color density or the like, can be formed. SOLUTION: A coloring material accepting layer coating liquid including fine inorganic pigment particles and a water-soluble resin is applied on at least either one side of a base. Simultaneously with the application or in the midway of the drying of the formed applied layer and before the manifestation of the falling rate drying speed of the applied layer, a cross-linker solution, which includes a cross-linker for cross-linking the water-soluble resin, is given in the applied layer so as to obtain a coloring material accepting layer by curing the applied layer given by the solution in order to obtain the ink jet recording sheet having the coloring material accepting layer. Both the coloring material accepting layer coating liquid and the cross-linker solution include a mordant. Further, the coating amount ratio (by weight) between the coating amount of the mordant led from the coloring material accepting layer coating liquid and the coating amount of the mordant led from the solution including both the cross-linker and the mordant is set to be 30:1 to 1:30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid ink using a dye or a pigment as a coloring material, such as an aqueous ink or an oil-based ink, or a solid ink which is solid at normal temperature and is melted and liquefied for printing. More particularly, the present invention relates to a recording sheet having excellent ink receiving performance.

[0002]

2. Description of the Related Art In recent years, with the rapid development of the information industry, various information processing systems have been developed, and recording methods and apparatuses suitable for the information systems have been developed and put into practical use. Among the above recording methods, the ink jet recording method,
It is widely used not only in offices but also in so-called home use because of its ability to record on various types of recording materials, relatively inexpensive hardware (devices), compactness, and excellent quietness. ing.

Further, with the recent increase in resolution of ink jet printers, it has become possible to obtain so-called photo-like high-quality recorded materials. On the other hand, with the development of hardware (devices), various recording sheets for inkjet recording have been developed. As the characteristics required for the recording sheet for the inkjet recording, generally,
(1) fast drying (high ink absorption speed), (2) proper and uniform ink dot diameter (no bleeding), and (3) high dot roundness ,
(4) high color density; (5) high color developability (saturation) (no dullness); (6) good light fastness and water fastness of the printed portion; (7) recording sheet Ink receiving performance such as high whiteness, (8) good storage stability of the recording sheet (no yellowing during long-term storage),
(9) It is difficult to deform and the dimensional stability is good (curl is sufficiently small). (10) The hard running property is good. Further, in addition to the above-described properties, the glossy, surface smoothness,
A photographic paper-like texture similar to silver halide photography is also required.

Examples of recording sheets used for ink jet recording include, for example, JP-A-55-51583, JP-A-55-144172, JP-A-55-150395, and JP-A-55-150395.
Nos. 6-148852, 56-148583, 56
148584, 56-148585, 57-
14091, 57-38185, 57-129
No. 778, No. 57-129979, No. 60-2190
No. 84, 60-245588, etc.
It is known that a pigment such as silica and a water-soluble binder are coated on a support such as paper or plastic film. However, all of these proposed recording sheets have extremely low gloss and are insufficient for use as photo glossy paper.

Further, Japanese Patent Application Laid-Open Nos. Hei 2-276670 and Hei 3-
No. 215082, No. 3-281383, No. 6-199
No. 035 and other publications propose a recording sheet using a pseudo-boehmite sol and a water-soluble binder. These recording sheets satisfy the required properties to some extent in terms of gloss, but have problems such as high production cost of pseudo-boehmite particles and difficulty in preparing a coating solution.

Further, recording materials using various water-soluble polymers in order to obtain glossiness have been proposed. For example, JP-A-58-89391, JP-A-58-134784, and JP-A-5-134784
8-134786, 60-44386, 60-
132785, 60-145879, 60-1
No. 68651, No. 60-171143, No. 60-17
No. 1,143, etc. are known in which polyvinyl alcohol, polyvinylpyrrolidone, gelatin and the like are coated on a support such as paper or plastic film. These recording sheets are also excellent in glossiness, but inferior in ink quick-drying properties, and are insufficient for use as photo glossy paper.

On the other hand, Japanese Patent Application Laid-Open No.
Nos. 276789, 8-174992 and 1
JP-A-115308 and JP-A-11-192777 have proposed ink jet recording sheets.

However, in JP-A-7-276789, a coloring material receiving layer having a three-dimensional structure with a high porosity, formed of inorganic pigment fine particles and a water-soluble resin, is provided on a support. Recording sheets have been proposed. According to this configuration, the ink absorbency is improved, color mixture bleeding during printing is sufficiently suppressed, and an image with high resolution can be obtained. This color material receiving layer can be generally formed by containing a large amount of particles having a small particle size.
Since it is necessary to reduce the amount of the binder for forming the layer so that voids can be formed, when the coating layer is rapidly dried, cracks occur and the transparency and appearance of the colorant receiving layer are impaired. .

As a method for preventing the ink receiving layer from cracking, Japanese Patent Application Laid-Open No. 9-109545 proposes a method in which the viscosity of a binder in a coating liquid is relatively high. There is a possibility that coating or uneven coating may occur, and the level is not yet practically effective. Also, JP-A-7-76161, 10-
Japanese Patent No. 119423 discloses a method for preventing cracking using a coating solution composed of inorganic particles, polyvinyl alcohol (PVA), boric acid or borate. In this method, however, the viscosity of the coating solution increases and the workability increases. And there is also a problem with the temporal stability of the solution, and it has not reached a practically effective level.

Further, as an ink jet recording sheet provided with a color material receiving layer having a three-dimensional structure having a high porosity, JP-A-10-203006 and JP-A-10-21
Nos. 7601 and 11-20306. However, these recording sheets have excellent ink absorbency due to their constitution, have high ink receiving performance for forming high-resolution images, and exhibit high gloss. When stored for a long time, there is a problem that the solvent diffuses together with the dye in the colorant receiving layer, causing image bleeding with the passage of time (so-called "blur with time").

On the other hand, in recent years, extremely high performance has been required in terms of image stability after printing, such as bleeding over time and water resistance after printing, and the color purity and color density are brighter and clearer than ever before. There is a high demand for inkjet images with extremely high chroma, such as higher

As described above, while the colorant receiving layer is strong without cracks or the like, it has good ink absorption and can form a high-resolution image, and the formed image has light resistance and water resistance. In addition to the ink receiving performance such as excellent properties and glossiness, the image stability after printing (no bleeding over time, high water resistance) is further excellent, and it is more vivid, and the color purity and color density are higher. At present, an inkjet recording sheet capable of forming an inkjet image with extremely high saturation has not been provided yet.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and achieve the following objects. That is, first, the present invention does not reduce the other ink receiving performance, bleeding resistance with time after printing, water resistance, extremely excellent in glossiness, more vivid without smear,
An object of the present invention is to provide an ink jet recording sheet capable of forming an ink jet image having extremely high chroma such as higher color purity and color density. Secondly, an object of the present invention is to provide an ink jet recording sheet that is strong without cracks or the like, has good ink absorbency, and can form a high-resolution image. Thirdly, an object of the present invention is to provide an ink jet recording sheet in which a formed image exhibits high light resistance even under irradiation with light such as sunlight or a fluorescent lamp.

[0014]

Means for Solving the Problems The present inventors have made intensive studies on the ink receiving performance of the colorant receiving layer and obtained the following findings. (1) It is effective to use a large amount of mordant to improve the water resistance of the ink image and the bleeding resistance over time in a high-temperature and high-humidity environment, but the colorant receiving layer secures a high porosity. From the viewpoint of containing silica fine particles, since the silica surface is anionic, easily reacts with the cationic mordant used for the purpose of immobilizing the dye and agglomerates, in the coating solution for forming the colorant receiving layer There is a limit to the amount of mordant that can be added to a dye. On the other hand, even if the above-described aggregation can be avoided, it is not preferable that the ink penetrates into a deep region of the colorant receiving layer in terms of improving the saturation, and it is not sufficient to simply include a large amount of the ink. It is enough. (2) In order to avoid the aggregation of the above (1), without adding a mordant to the coating solution for forming a colorant receiving layer, a crosslinking agent and a mordant during coating of the coating solution or during drying after coating. Just supplying a mordant by applying a solution containing the solution (crosslinking agent solution)
Certainly, the water resistance near the surface of the color material receiving layer and the bleeding resistance over time are improved, but the penetration of the mordant into the color material receiving layer is limited, and when a large amount of ink is supplied at the time of printing, The ink penetrates deep into the colorant receiving layer, but water resistance and bleeding resistance over time cannot be obtained in this part. As a result, the ink diffuses in the layer to form bleeding, and the observed image has saturation,
It lacks sharpness. (3) On the other hand, applying a coating solution for the colorant receiving layer, at the same time as the coating, or during the drying of the formed coating layer and before the coating layer shows a reduced drying rate, Even in the case of a production method in which a coating layer is formed by applying a crosslinking agent solution containing a crosslinking agent and a mordant (WOW method: Wet On Wet method),
If a large amount of the mordant is used, the mordant itself may form a coating and cause deterioration in surface properties such as uneven gloss.

The means for solving the above problems are as follows. <1> In an ink jet recording sheet having a color material receiving layer on at least one surface of a substrate, the color material receiving layer contains inorganic pigment fine particles having an average primary particle diameter of 20 nm or less, a water-soluble resin, and a mordant. A colorant receiving layer coating solution to be applied, and simultaneously with the application, or during the drying of the formed coating layer, before the coating layer exhibits a reduced drying rate, the water-soluble After applying a solution containing a cross-linking agent capable of cross-linking the resin and a mordant, the applied layer obtained by applying the solution is cross-linked and cured, and the coating amount of the mordant introduced from the colorant-receiving layer coating solution. (cp ¹⁾ and the coating amount of the mordant introduced from a solution containing a crosslinking agent and a mordant (cp ²⁾ and the coating amount ratio of (cp ^1: cp ^2; weight) 30: 1
１ ： 1: 30, which is an inkjet recording sheet.

<2> The mordant contained in the coating solution for the colorant receiving layer comprises a copolymer of a mordant monomer and a non-mordant monomer, and the copolymerization ratio of the mordant monomer in the copolymer is 30 mol% or more. An inkjet recording sheet according to <1>. That is, as the mordant contained in the colorant-receiving layer coating solution, the above-mentioned copolymer is preferable from the viewpoint of compatibility in the coating solution (it hardly causes aggregation), and as the mordant in the solution containing the crosslinking agent, However, the present invention is not limited thereto, and may be the same or different.

<3> The color material receiving layer has a porosity of 50 to 80.
% Of the inorganic pigment fine particles (i) and the water-soluble resin (p) (i: p / weight ratio).
The inkjet recording sheet according to <1> or <2>, wherein the ratio is 5: 1 to 10: 1.

<4> Inorganic pigment fine particles have a surface
The inkjet recording sheet according to any one of the above items <1> to <3>, which is silica having ^{2 to} 3 silanol groups per m ² .

<5> The inkjet recording sheet according to any one of <1> to <4>, wherein the crosslinking agent is boric acid or a boron compound.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The ink jet recording sheet of the present invention is obtained by applying a coating material for forming a colorant receiving layer (coating solution for a colorant receiving layer) on a substrate, and simultaneously or simultaneously with the coating. A WOW method (Wet method) in which a solution containing a cross-linking agent (cross-linking agent solution) is applied to the coating layer and the cross-linking is hardened before the coating layer shows a reduced drying rate during the drying of the layer.
On Wet method), a colorant receiving layer formed by
The colorant receiving layer coating solution and the crosslinking agent solution each contain a mordant, and the amount of the mordant introduced from the colorant receiving layer coating solution (cp ¹ ) and the amount of the mordant introduced from the crosslinking agent solution (cp1) cp ² ) and the application amount ratio (cp ¹ : cp ² ; weight) to 3
0: 1 to 1:30. Hereinafter, the inkjet recording sheet of the present invention will be described in detail through a method for producing the same.

<Preparation of inkjet recording sheet: W
OW Method> The ink jet recording sheet of the present invention has a color material receiving layer on at least one surface of the substrate, and the color material receiving layer is a WOW method, that is, the average primary particle diameter is 20 nm.
A colorant receiving layer coating solution containing the following inorganic pigment fine particles, a water-soluble resin, and a mordant is applied, and the coating layer is dried at the same time as the application, or during the drying of the formed coating layer, at a reduced drying rate. Before showing a solution containing a crosslinking agent capable of crosslinking the water-soluble resin in the coating layer and a mordant (hereinafter, referred to as
It may be referred to as “crosslinking agent solution”. ), The coating layer to which the solution has been applied is crosslinked and cured.

That is, the present invention is characterized in that a mordant is added in advance to both the coating material for the colorant receiving layer and the crosslinking agent solution to be applied thereafter. A mordant is added to such an extent that aggregation does not adversely affect layer formation with the silica fine particles, and the amount of the mordant supplied by applying the crosslinking agent solution is supplemented. That is, when the mordant is added to the colorant receiving layer coating solution, the mordant is cationic, so that coagulation may occur in the presence of inorganic pigment fine particles having an anionic charge on the surface, such as silica, Since the mordant is also added to the crosslinking agent solution to be applied later, it may be contained to such an extent that it does not agglomerate.

As the color material receiving layer, adsorbing and retaining most of the ink near the surface on the ink receiving side is a point that forms a clear and clear image (highly saturated image) without blemishes. Is preferred. That is, the color material receiving layer preferably has a state in which the mordant is maintained at a high concentration near the surface on the ink receiving side, and the concentration gradually decreases from the surface in the thickness direction.

Therefore, in the present invention, in addition to applying a cross-linking agent solution containing a mordant after application by employing the WOW method, a layer is formed by using a colorant receiving layer coating solution to which a mordant is previously added. Since a large amount of mordant exists near the surface and is also supplied into the layer, even when a large amount of ink is supplied during printing, most of the ink can be retained near the layer surface and permeated into the layer. Ink bleeding can also be avoided. As a result, bleeding resistance over time, water resistance can be improved, and there is no blemishes, and the color purity is higher.
An extremely high-saturation inkjet image can be formed. Further, the color density (image density) is relatively improved by increasing the content of the mordant.

The colorant receiving layer of the ink jet recording sheet of the present invention is obtained by reacting a coating solution containing fine inorganic pigment particles, a water-soluble resin and a mordant, and a crosslinking agent solution containing a crosslinking agent and a mordant with the crosslinking agent. It can also be obtained by simultaneously applying a barrier liquid made of a material not to be used (provided that at least one of a solution containing a cross-linking agent or a barrier liquid contains a mordant) onto a substrate and curing the same.

Here, the application amount (cp ¹ ) of the mordant introduced from the coating material for the colorant receiving layer and the application amount (cp ² ) of the mordant introduced from the solution containing the cross-linking agent and the mordant. The quantitative ratio (cp ¹ : cp ² ; weight) is set to 1:30 to 30: 1.
Above all, the coating amount ratio is particularly preferably 1: 5 to 14: 1.

The ratio of cp ¹ : cp ² is less than 1:30, that is,
If the coating amount (cp ¹ ) of the mordant introduced from the colorant receiving layer coating solution is too small compared to the amount introduced from the crosslinking agent solution, the amount of the mordant penetrating into the layer by applying the crosslinking agent solution is limited. Ink is not adsorbed and easily diffuses in the layer (water resistance and bleeding resistance over time are not sufficient), and an image with high chroma may not be obtained. Conversely, if the ratio exceeds 30: 1, that is, if the coating amount of the mordant introduced from the coating material for the colorant receiving layer is too large as compared with the introduction amount from the crosslinking agent solution, aggregation occurs in the coating solution and a high porosity occurs. In addition to the risk of interfering with the formation of the ink layer, the amount of mordant near the surface layer introduced from the crosslinking agent solution is relatively small, so most of the ink near the surface layer is not adsorbed and retained, and penetrates into the layer. As a result, the ink may be distributed in the thickness direction, causing smearing and making it impossible to form a high-saturation image.

In the present invention, the coating material for the colorant-receiving layer containing at least the inorganic pigment fine particles, the water-soluble resin and the mordant is a coating solution for forming a porous layer, and can be prepared, for example, as follows. . That is, the average primary particle diameter is 20 nm.
The following silica fine particles are added to water (for example,
20% by weight), using a high-speed rotating wet colloid mill (for example, CLEARMIX (manufactured by M Technique Co., Ltd.)) at 10,000 rpm (preferably 5000 to 2).
After dispersion for 20 minutes (preferably 10 to 30 minutes) under the condition of high-speed rotation of 0000 rpm, an aqueous polyvinyl alcohol solution (for example, PV
A) and further add a desired mordant (for example,
(To be 20% by weight of silica (by weight)), and dispersion is performed under the same rotation conditions as described above. The obtained coating solution is a uniform sol, and by coating this on a substrate by the following coating method, a porous colorant receiving layer having a three-dimensional network structure can be formed. The coloring material receiving layer coating solution, if necessary,
Further, a surfactant, a pH adjuster, an antistatic agent and the like can be added.

The application of the coating material for the colorant receiving layer can be performed by a known coating method such as an extrusion die coater, an air doctor coater, a bread coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, and a bar coater. .

In the present invention, a solution containing at least a cross-linking agent and a mordant (cross-linking agent solution) is introduced into a coating layer formed by coating with a colorant-receiving layer coating solution, and dried to be cured by a cross-linking reaction. A colorant receiving layer can be obtained. The cross-linking agent coating liquid is applied simultaneously with or after the application of the colorant receiving layer coating liquid and before the coating layer exhibits a reduced drying rate.

In the latter case, after applying the coating material for the colorant receiving layer, while the coating layer shows a constant rate of drying, a crosslinking agent solution containing at least a crosslinking agent and a mordant is introduced. It is preferably manufactured. Here, “before the coating layer exhibits a reduced drying rate” usually refers to a few minutes immediately after the application of the coating material for the colorant receiving layer, during which the solvent in the applied coating layer is used. Shows a constant rate drying rate, which is a phenomenon in which the content of the compound decreases in proportion to time. For the time indicating the constant rate drying rate, see the Chemical Engineering Handbook (p. 70).
7-712, published by Maruzen Co., Ltd., October 25, 1980
Date).

As described above, after the application of the coating material for the colorant receiving layer,
The coating is dried until it exhibits a rate of drying, which is generally dried at 50 to 180 ° C. for 0.5 to 10 minutes.
Minutes (preferably, 0.5 to 5 minutes). The drying time varies depending on the coating amount, but the above range is appropriate.

A method of dipping the substrate on which the coating layer has been formed in a crosslinking agent solution before the coating layer exhibits a reduced rate of drying, further applying the crosslinking agent solution on the coating layer. Spraying, spraying, etc.,
For example, a crosslinking agent and a mordant can be introduced.

In the above method, as a coating method for applying the crosslinking agent solution, for example, a curtain flow coater,
Known application methods such as an extrusion die coater, an air doctor coater, a bread coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, and a bar coater can be used. However, extrusion die coaters, curtain flow coaters,
It is preferable to use a method, such as a bar coater, in which the coater does not directly contact the already formed coating layer.

The coating amount of a coating solution (crosslinking agent solution) containing at least a crosslinking agent and a mordant applied on the colorant receiving layer is generally 0.01 to 10 g / m ^{2 in} terms of a crosslinking agent. And 0.05 to 5 g / m ² is preferable. Further, in terms of mordant, 0.2 to 3.0 g / m ² is preferable,
0.3-2.5 g / m < ² > is more preferable. 0.2 g / m ²
If it is less than 3, the gloss may be reduced, and may be 3.0 g / m.
^If it exceeds ² , the ink absorbency may deteriorate.

After the application of the cross-linking agent solution, generally 40 to 1
Heating is performed at 80 ° C. for 0.5 to 30 minutes to perform drying and curing. Especially, it is preferable to heat at 40 to 150 ° C. for 1 to 20 minutes. For example, when borax or boric acid is used as the crosslinking agent contained in the crosslinking agent solution,
It is preferable to perform heating at １００100 ° C. for 5２０20 minutes.

The cross-linking agent coating liquid may be applied simultaneously with the application of the colorant receiving layer coating liquid. In this case, a colorant receiving layer coating solution and a crosslinking agent solution containing a crosslinking agent and a mordant are simultaneously applied to the substrate so that the colorant receiving layer coating solution comes into contact with the substrate (multilayer coating), and then dried. By curing, a colorant receiving layer can be formed.

The simultaneous coating (multilayer coating) can be performed by a coating method using, for example, an extrusion die coater or a curtain flow coater. After the simultaneous coating, the formed coating layer is dried. In this case, the drying is generally performed by heating the coating layer at 40 to 150 ° C. for 0.5 to 10 minutes, preferably 40 to 100 ° C.
It is performed by heating at a temperature of 0.5 to 5 minutes. For example, when using borax or boric acid as a cross-linking agent contained in the cross-linking agent solution, it is preferable to heat at 60 to 100 ° C. for 5 to 20 minutes.

When the simultaneous coating (multilayer coating) is performed by, for example, an extrusion die coater, the two kinds of coating liquids discharged simultaneously are close to the discharge port of the extrusion die coater, that is, before being transferred onto the substrate. A multilayer is formed, and in that state, a multilayer coating is performed on the substrate. The two-layer coating solution that has been layered before coating is likely to cause a crosslinking reaction at the interface between the two components when it is transferred to the substrate.Therefore, near the discharge port of the extrusion die coater, the two components to be discharged are mixed. The viscosity tends to increase, which may hinder the application operation.
Therefore, in the simultaneous coating as described above, the coating of the colorant receiving layer coating solution and the crosslinking agent solution containing the crosslinking agent and the mordant, together with the barrier layer solution (intermediate layer solution) made of a material that does not react with the crosslinking agent. ) Is preferably interposed between the two liquids to perform simultaneous three-layer coating.

The barrier layer solution can be selected without any particular limitation as long as it can form a liquid film without reacting with the crosslinking agent. For example, an aqueous solution containing a trace amount of a water-soluble resin that does not react with the crosslinking agent, water, or the like can be used. The water-soluble resin is used in consideration of applicability for the purpose of a thickener and the like, for example, hydroxypropyl methyl cellulose-
And methylcellulose, hydroxyethylmethylcellulose, polyvinylpyrrolidone and gelatin. Incidentally, the mordant may be contained in the barrier layer liquid.

After the color material receiving layer is formed on the substrate, the color material receiving layer is calendered through a roll nip under heat and pressure using, for example, a super calendar, a gloss calendar, etc. , Glossiness, transparency and coating strength can be improved. However, since the calendering treatment may cause a decrease in the porosity (that is, the ink absorbency may be reduced), it is necessary to set a condition under which the porosity does not decrease much.

The roll temperature for calendering is preferably from 30 to 150 ° C., more preferably from 40 to 100 ° C. The linear pressure between the rolls during the calendering treatment is preferably 50 to 400 kg / cm, and is preferably 10 to 400 kg / cm.
0 to 200 kg / cm is more preferable.

In the case of ink jet recording, the layer thickness of the colorant receiving layer needs to have an absorption capacity to absorb all of the liquid droplets, and thus needs to be determined in relation to the porosity in the layer. is there. For example, if the ink amount is 8 nL / mm ²
If the porosity is 60%, the layer thickness is about 15 μm.
The above film is required. Considering this point, in the case of inkjet recording, the layer thickness of the colorant receiving layer is 1
0 to 50 μm is preferred.

The pore diameter of the colorant receiving layer is preferably from 0.005 to 0.030 μm in median diameter, and from 0.01 to 0.030 μm.
0.025 μm is more preferred. The porosity and the median pore diameter can be measured using a mercury porosimeter (trade name: Pore Sizer 9320-PC2, manufactured by Shimadzu Corporation).

The color material receiving layer is preferably excellent in transparency. As a guide, the haze value when the color material receiving layer is formed on a transparent film substrate is 30%.
Or less, and more preferably 20% or less. The haze value is measured using a haze meter (HGM).
-2DP: Suga Test Instruments Co., Ltd.).

<Ink Jet Recording Sheet> The ink jet recording sheet of the present invention has a colorant receiving layer on at least one surface of the substrate.
It is formed on a substrate by a method. -Coloring material receiving layer- The coloring material receiving layer, inorganic pigment fine particles, a water-soluble resin,
It comprises at least a crosslinking agent capable of crosslinking the water-soluble resin and a mordant, and if necessary, other components such as a light resistance improving agent.

(Inorganic Pigment Fine Particles) The colorant receiving layer contains anhydrous pigment fine particles having an average primary particle diameter of 20 nm or less. Examples of the inorganic pigment fine particles include, for example, silica fine particles, colloidal silica, titanium dioxide, barium sulfate, calcium silicate, zeolite, kaolinite, halloysite, mica, talc, calcium carbonate, magnesium carbonate, calcium sulfate, boehmite, pseudo boehmite, and the like. Can be mentioned. Among them, silica fine particles are particularly preferable.

Since the silica fine particles have a particularly large specific surface area, they have high ink absorption and retention efficiency, and have a low refractive index, so that if they are dispersed to an appropriate particle size, transparency is imparted to the receptor layer. And high color density and good color developability can be obtained. Transparency of the receiving layer means that O
It is important not only in applications requiring transparency such as HP but also in recording sheets such as photo glossy paper from the viewpoint of obtaining high color density and good color-forming gloss.

The average primary particle diameter of the inorganic pigment fine particles is preferably 20 nm or less, more preferably 10 nm or less, and most preferably 3 to 10 nm.

The silica fine particles have a sinoral group on the surface thereof, and the particles easily adhere to each other due to hydrogen bonding by the silanol group. Therefore, when the average primary particle diameter is 10 nm or less as described above, the porosity is large. The structure can be formed, and the ink absorption characteristics can be effectively improved.

The silica fine particles are roughly classified into wet process particles and dry process particles according to the production method. In the wet method, the mainstream is a method in which active silica is generated by acid decomposition of a silicate, which is appropriately polymerized, coagulated and settled to obtain hydrated silica. On the other hand, the dry method is a method based on high-temperature gas phase hydrolysis of silicon halide (flame hydrolysis method), in which silica sand and coke are heated and reduced by an arc in an electric furnace,
A method of obtaining anhydrous silica by a method of oxidizing this with air (arc method) is mainly used.

The hydrous silica and anhydrous silica obtained by these methods differ in the density of silanol groups on the surface, the presence or absence of vacancies, and the like, and exhibit different properties. However, in the case of anhydrous silica (silicic anhydride), Is particularly preferable because a three-dimensional structure having a particularly high porosity is easily formed. Although the reason for this is not clear, in the case of hydrous silica, the density of silanol groups on the surface of the fine particles is as large as 5 to 8 / nm ² , and the silica fine particles are likely to be densely aggregated (aggregate). In the case of (1), since the density of silanol groups on the surface of the fine particles is as small as ² to 3 / nm ² , sparse soft coagulation (flocculate) is caused, and as a result, it is presumed that the structure has a high porosity. . Therefore, in the present invention, it is preferable to use silica (silica fine particles) having a density of 2 to 3 silanol groups / nm ² on the surface of the fine particles.

From the viewpoint of transparency, the type of resin to be combined with the silica fine particles is important. When anhydrous silica is used, the water-soluble resin is preferably polyvinyl alcohol (PVA). 99% PVA is more preferred, and PVA with a saponification degree of 70-90% is most preferred.

The PVA has a hydroxyl group in its structural unit, and the hydroxyl group and a silanol group on the surface of the silica fine particles form a hydrogen bond to form a three-dimensional network structure in which secondary particles of the silica fine particles are chain units. Easy to do. It is considered that by forming the three-dimensional network structure, a colorant receiving layer having a porous structure with a high porosity can be formed. The porous colorant receiving layer thus obtained is used for inkjet recording.
The ink is rapidly absorbed by the capillary phenomenon, and a dot having good roundness without ink bleeding can be formed.

The content ratio of inorganic pigment fine particles (preferably silica fine particles; i) and water-soluble resin (p) [PB ratio (i:
p), weight of inorganic pigment fine particles per 1 part by weight of water-soluble resin] greatly affects the film structure of the colorant receiving layer.
That is, as the PB ratio increases, the porosity, pore volume, and surface area (per unit weight) increase. Specifically, the P
The B ratio (i: p) is preferably 1.5: 1 to 10: 1. When the PB ratio exceeds 10: 1, that is, when the PB ratio is too large, the film strength is reduced and cracks may easily occur during drying, and the PB ratio is less than 1.5: 1, that is, the PB ratio is too small. As a result, the voids are more likely to be closed by the resin, and as a result, the porosity may decrease and the ink absorbency may decrease.

When the recording sheet passes through the transport system of the ink jet printer, stress may be applied to the recording sheet.
The colorant receiving layer needs to have sufficient film strength. Further, when the sheet is cut into a sheet, the color material receiving layer needs to have a sufficient film strength in order to prevent the color material receiving layer from being cracked or peeled off. In this case, the PB ratio is preferably 5: 1 or less, and is preferably 2: 1 or more from the viewpoint of securing high-speed ink absorption by an inkjet printer.

For example, anhydrous silica fine particles having an average primary particle diameter of 20 nm or less and a water-soluble resin are mixed with a PB ratio of 2: 1 to 5:
When a coating liquid completely dispersed in an aqueous solution in step 1 is applied onto a substrate and the coating layer is dried, a three-dimensional network structure in which secondary particles of silica fine particles are formed as a chain unit is formed, and the average pore diameter is 30 nm. Below, the porosity is 50% or more, and the pore specific volume is 0.1% or less.
A translucent porous film having a specific surface area of at least 5 ml / g and a specific surface area of at least 100 m ² / g can be easily formed.

(Water-soluble resin) As the water-soluble resin,
For example, a resin having a hydroxyl group as a hydrophilic structural unit, such as polyvinyl alcohol (PVA), cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, silanol-modified polyvinyl alcohol, polyvinyl acetal, a cellulose resin [methyl cellulose (MC), ethyl cellulose ( EC), hydroxyethylcellulose (HEC), carboxymethylcellulose (CMC), etc.], chitins, chitosans, starch; polyethylene oxide (PEO) which is a resin having an ether bond, polypropylene oxide (PP
O), polyethylene glycol (PEG), polyvinyl ether (PVE); and resins having an amide group or an amide bond, such as polyacrylamide (PAAM) and polyvinyl pyrrolidone (PVP). Further, having a carboxyl group as a dissociable group, polyacrylate,
Maleic acid resins, alginates and gelatins can be mentioned. Among the above, polyvinyl alcohols are particularly preferred.

The content of the water-soluble resin is preferably from 9 to 40% by weight, and more preferably from 16 to 33% by weight, based on the total solid weight of the colorant receiving layer. The content is
If the amount is less than 9% by weight, the film strength is reduced, and cracks may easily occur during drying. If the amount is more than 40% by weight, the voids are easily closed by the resin, resulting in a decrease in the porosity and ink. Absorption may decrease.

The inorganic pigment fine particles and the water-soluble resin, which mainly constitute the colorant receiving layer, may be a single material or a mixture of a plurality of materials.

(Mordant) The mordant is a cationic polymer, and interacts with a liquid ink having an anionic dye as a coloring material by being present in the coloring material receiving layer to stabilize the coloring material. Water resistance and bleeding over time can be improved.

However, when this is added directly to the coating material for the colorant receiving layer (coating solution for forming the colorant receiving layer), the
A large amount cannot be added due to easy aggregation with inorganic pigment fine particles having an anionic charge.However, it is added to the colorant receiving layer coating solution within a range that does not cause aggregation, and is further independently prepared. A sufficient mordant can be present not only in the vicinity of the surface of the colorant receiving layer but also in the layer by adding it to the crosslinker solution and providing it together with the crosslinker to the layer after application. Thereby, the bleeding over time under water resistance and high temperature and high humidity environment etc. is further improved, and it is more vivid and clear,
An image with excellent saturation can be obtained. The mordant added to both solutions may be the same or different.

-Mordant and the like contained in the coating solution for the colorant receiving layer-The cationic mordant includes a
A polymer mordant having a tertiary to tertiary amino group or a quaternary ammonium group is preferably used, but a cationic non-polymer mordant can also be used. Examples of the polymer mordant include a homopolymer of a monomer having a primary to tertiary amino group and a salt thereof, or a monomer (mordanting monomer) having a quaternary ammonium group, or a mordant monomer and another monomer (hereinafter, referred to as a mordant monomer). Those obtained as a copolymer or a condensed polymer with “non-mordanting polymer”) are preferred. Also,
These polymer mordants can be used in the form of either a water-soluble polymer or water-dispersible latex particles.

Examples of the monomers (mordanting monomers) include trimethyl-p-vinylbenzylammonium chloride, trimethyl-m-vinylbenzylammonium chloride, triethyl-p-vinylbenzylammonium chloride, and triethyl-m-vinylbenzylammonium. Chloride, N, N-dimethyl-N-ethyl-Np-vinylbenzylammonium chloride,
N, N-diethyl-N-methyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-Nn
-Propyl-Np-vinylbenzylammonium chloride, N, N-dimethyl-Nn-octyl-Np
-Vinylbenzylammonium chloride, N, N-dimethyl-N-benzyl-Np-vinylbenzylammonium chloride, N, N-diethyl-N-benzyl-
Np-vinylbenzylammonium chloride, N,
N-dimethyl-N- (4-methyl) benzyl-Np-
Vinylbenzylammonium chloride, N, N-dimethyl-N-phenyl-Np-vinylbenzylammonium chloride,

Trimethyl-p-vinylbenzylammonium bromide, trimethyl-m-vinylbenzylammonium bromide, trimethyl-p-vinylbenzylammonium sulfonate, trimethyl-m-vinylbenzylammonium sulfonate, trimethyl-p-vinylbenzylammonium acetate, trimethyl- m
-Vinylbenzylammonium acetate, N, N, N
-Triethyl-N-2- (4-vinylphenyl) ethylammonium chloride, N, N, N-triethyl-N
-2- (3-vinylphenyl) ethylammonium chloride, N, N-diethyl-N-methyl-N-2- (4
-Vinylphenyl) ethylammonium chloride,
N, N-diethyl-N-methyl-N-2- (4-vinylphenyl) ethylammonium acetate;

N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth)
Acrylate, N, N-diethylaminopropyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N Methyl chloride of N-diethylaminopropyl (meth) acrylamide,
Ethyl chloride, methyl bromide, ethyl bromide, a quaternary compound with methyl iodide or ethyl iodide, or a sulfonate, an alkyl sulfonate, an acetate or an alkyl carboxylate in which an anion thereof is substituted, may be mentioned.

Among them, specifically, for example, trimethyl-2- (methacryloyloxy) ethylammonium chloride, triethyl-2- (methacryloyloxy)
Ethylammonium chloride, trimethyl-2- (acryloyloxy) ethylammonium chloride, triethyl-2- (acryloyloxy) ethylammonium chloride, trimethyl-3- (methacryloyloxy) propylammonium chloride, triethyl-
3- (methacryloyloxy) propyl ammonium chloride, trimethyl-2- (methacryloylamino)
Ethyl ammonium chloride, triethyl-2- (methacryloylamino) ethyl ammonium chloride,
Trimethyl-2- (acryloylamino) ethylammonium chloride, triethyl-2- (acryloylamino) ethylammonium chloride, trimethyl-3
-(Methacryloylamino) propyl ammonium chloride, triethyl-3- (methacryloylamino) propyl ammonium chloride, trimethyl-3- (acryloylamino) propyl ammonium chloride,
Triethyl-3- (acryloylamino) propylammonium chloride,

N, N-dimethyl-N-ethyl-2- (methacryloyloxy) ethylammonium chloride,
N, N-diethyl-N-methyl-2- (methacryloyloxy) ethylammonium chloride, N, N-dimethyl-N-ethyl-3- (acryloylamino) propylammonium chloride, trimethyl-2- (methacryloyloxy) ethylammonium Bromide, trimethyl-3- (acryloylamino) propylammonium bromide, trimethyl-2- (methacryloyloxy) ethylammonium sulfonate, trimethyl-
3- (acryloylamino) propyl ammonium acetate and the like can be mentioned. In addition, as copolymerizable monomers, N-vinylimidazole, N-vinyl-2-methylimidazole and the like can also be mentioned.

The non-mordant polymer does not contain a basic or cationic moiety such as a primary to tertiary amino group and a salt thereof, or a quaternary ammonium base, and has an interaction with a dye in an inkjet ink. A monomer that does not show or has substantially small interaction. Examples of the non-mordanting monomer include: (meth) acrylic acid alkyl ester; (meth) acrylic acid cycloalkyl ester such as (meth) acrylic acid cycloacrylate; (meth) acrylic acid aryl ester such as phenyl (meth) acrylate; Aralkyl esters such as benzyl (meth) acrylate; aromatic vinyls such as styrene, vinyltoluene and α-methylstyrene; vinyl acetate, vinyl propionate;
Vinyl esters such as vinyl versatate; allyl esters such as allyl acetate; halogen-containing monomers such as vinylidene chloride and vinyl chloride; vinyl cyanides such as (meth) acrylonitrile; olefins such as ethylene and propylene. No.

As the alkyl (meth) acrylate, (meth) acrylic acid having 1 to 18 carbon atoms in the alkyl moiety is used.
Alkyl acrylates are preferred, for example, methyl (meth) acrylate, ethyl (meth) acrylate,
Propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate,
Examples include hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and stearyl (meth) acrylate. Among them, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and hydroxyethyl methacrylate are preferred. The non-mordanting monomers can also be used alone or in combination of two or more.

In the present invention, the mordant (polymer mordant) contained in the coating solution for the colorant receiving layer is preferably a copolymer of a mordant monomer and a non-mordant polymer. When a copolymer of a mordant monomer (m ¹ ) and a non-mordant polymer (m ² ; another monomer) is used as the polymer mordant,
The copolymerization ratio of the mordant monomer (m ¹ ) is preferably 30% or more, and the copolymerization ratio (m ¹ / m ² ) is 40/60 to 80 /
20 is more preferred. When the ratio of the mordant monomer (m ¹ ) in the copolymerization ratio is less than 30%, the polymer mordant itself may aggregate and cannot be mixed with inorganic pigment fine particles such as silica.

The molecular weight of the polymer mordant is 1
000 to 200,000 is preferred. The molecular weight is 100
If it is less than 0, the water resistance tends to be insufficient, and 2
If it exceeds 00000, the viscosity may be too high and the handling adequacy may decrease.

-Mordant contained in the crosslinking agent solution together with the crosslinking agent-As the mordant added to the crosslinking agent solution, the mordant usable in the above-mentioned coating solution for the colorant receiving layer (that is, a homopolymer of a mordant monomer, A copolymer or a condensed polymer of a mordant monomer and a non-mordant polymer) or the following mordant can be used. For example, polydiallyldimethylammonium chloride, polymethacryloyloxyethyl-β-hydroxyethyldimethylammonium chloride, polyethyleneimine, polyallylamine, polyallylamine hydrochloride, polyamide-polyamine resin, cationized starch, dicyandiamide formalin condensate, dimethyl-2- Hydroxypropyl ammonium salt polymer, polyamidine, polyvinylamine and the like can be mentioned. The molecular weight of these mordants is also preferably about 1,000 to 200,000 for the same reason as described above.

The non-polymeric mordant is preferably a compound having a quaternary ammonium salt group having a total number of carbon atoms of 12 or more, preferably 18 or more. In addition, water-soluble metal salts, AlCl ₃ , Al ₂ (SO ₄ ) ₃ , polyaluminum chloride, MgCl ₂ , Mg (NO ₃ ) ₂ , alum and the like can also be used as mordants.

Inclusion of a mordant in the coating solution for the colorant receiving layer
As the amount, between the inorganic pigment fine particles and the
Any range that does not cause agglomeration that causes
0.6 to 3 with respect to the content (weight) of the inorganic pigment fine particles.
5% by weight is preferable, and 3 to 25% by weight is more preferable.
When the content is less than 0.6% by weight, water resistance and water resistance
Bleeding over time could not be sufficiently obtained, and the chroma might be poor.
If it exceeds 5% by weight, inorganic pigment fine particles such as silica that coexist
Aggregation with offspring may occur. Meanwhile, the crosslinking agent solution
The content of the mordant in the is introduced from the colorant receiving layer coating solution
Of mordant applied and mordant introduced from crosslinker solution
Of coating agent to coating amount (cp ¹: Cp^Two; Weight) is 30: 1
１ ： 1: 30 in the range.

The total content (dry weight) of the mordant in the color material receiving layer is preferably 0.5 to 30.0% by weight, based on the solid content of the color material receiving layer excluding the mordant. 0.0-20.0% by weight is more preferred. If the content is less than 0.5% by weight, sufficient water resistance and bleeding resistance over time may not be obtained, and if it exceeds 30.0% by weight, the ink absorbency may deteriorate.

(Crosslinking Agent) The colorant-receiving layer of the ink jet recording sheet of the present invention contains at least a crosslinking agent and a mordant in a coating layer (porous layer) containing a mordant in advance together with inorganic pigment fine particles and a water-soluble resin. A layer in which a solution (crosslinking agent solution) is applied and the water-soluble resin is cured by a crosslinking reaction by the crosslinking agent.

The cross-linking agent solution is applied at the same time as when the coating solution for forming the porous color material receiving layer (color material receiving layer coating solution) is applied, or when the color material receiving layer coating solution is applied. It is preferable that the coating be performed before the formed coating layer exhibits a reduced drying rate. By this operation, it is possible to effectively prevent the occurrence of cracks that occur during the drying of the coating layer. That is, the cross-linking agent solution permeates into the coating layer at the same time as when the coating liquid is applied or before the coating layer exhibits a reduced drying rate, and quickly reacts with the water-soluble resin in the coating layer, Gelling (curing) water-soluble resin
By doing so, the film strength of the coating layer is immediately and greatly improved.

As a crosslinking agent capable of crosslinking the water-soluble resin,
Is suitable in relation to the water-soluble resin used for the colorant receiving layer.
The cross-linking reaction is particularly rapid.
In view of the following, a boron compound is preferable.
Sand, boric acid, borate (eg, orthoborate, In
BO_Three, ScBO_Three, YBO_Three, LaBO_Three, Mg_Three(BO_Three)
_Two , Co_Three(BO_Three)_Two, Diborate (eg, Mg_TwoB_TwoO
_Five, Co_TwoB_TwoO_Five), Metaborate (eg, LiB
O_Two, Ca (BO_Two)_Two, NaBO_Two, KBO_Two), Tetraboric acid
Salt (eg, Na_TwoB_FourO₇・ 10H_TwoO), pentaborate
(For example, KB_FiveO₈・ 4H_Two O, Ca_TwoB₆O₁₁・ 7H_Two
O, CsB_FiveO_Five), Glyoxal, melamine holm
Aldehydes (eg, methylol melamine, alkylated
Methylol melamine), methylol urea, resole tree
Fats, polyisocyanates, epoxy resins, etc.
Can be. Among them, boron is preferred in that a crosslinking reaction occurs promptly.
Sand, boric acid and borate are preferred, especially water-soluble resins.
Can be used in combination with polyvinyl alcohol.
Is more preferable.

When gelatin is used as the water-soluble resin, the following compounds known as hardeners for gelatin can be used as crosslinking agents. For example, aldehyde compounds such as formaldehyde, glyoxal and glutaraldehyde; ketone compounds such as diacetyl and cyclopentanedione; bis (2-chloroethylurea) -2-hydroxy-4,6-dichloro-1,3,5
-Halogen compounds such as triazine, 2,4-dichloro-6-S-triazine sodium salt; divinylsulfonic acid, 1,3-vinylsulfonyl-2-propanol, N, N'-ethylenebis (vinylsulfonylacetate) Active vinyl compounds such as amide), 1,3,5-triacryloyl-hexahydro-S-triazine; N-methylol compounds such as dimethylolurea and methyloldimethylhydantoin;

Isocyanate compounds such as 1,6-hexamethylene diisocyanate; US Patent No. 301
Nos. 7280 and 29836311; aziridine compounds; carboximide compounds described in U.S. Pat. No. 3,100,704; epoxy compounds such as glycerol triglycidyl ether; and 1,6-hexamethylene-N, N '. Ethyleneimino compounds such as bisethyleneurea; halogenated carboxaldehyde compounds such as mucochloric acid and mucophenoxycyclolic acid; dioxane compounds such as 2,3-dihydroxydioxane; chromium alum, potassium alum, zirconium sulfate; Chromium acetate and the like. The crosslinking agent may be used alone or in combination of two or more.

The crosslinking agent solution is prepared by dissolving the crosslinking agent in water and / or an organic solvent. The concentration of the crosslinking agent in the crosslinking agent solution is 0.05% with respect to the weight of the crosslinking agent solution.
Is preferably from 10 to 10% by weight, and particularly preferably from 0.1 to 7% by weight. As a solvent constituting the crosslinking agent solution, water is generally used, and an aqueous mixed solvent containing an organic solvent miscible with the water may be used. As the organic solvent, any one can be used as long as it can dissolve the crosslinking agent, for example,
Alcohols such as methanol, ethanol, isopropyl alcohol and glycerin; ketones such as acetone and methyl ethyl ketone; esters such as methyl acetate and ethyl acetate;
Aromatic solvents such as toluene; ethers such as tetrahydrofuran; and halogenated carbon-based solvents such as dichloromethane.

(Other Components) The colorant receiving layer is mainly composed of the above-mentioned inorganic pigment fine particles and a water-soluble resin, but may further contain the following components as required. For the purpose of suppressing the deterioration of the coloring material, various ultraviolet absorbers, antioxidants, singlet oxygen quencher and the like may be included. Examples of the ultraviolet absorber include cinnamic acid derivatives, benzophenone derivatives, and benzotriazolylphenol derivatives. For example, α-cyano-phenyl butyl cinnamate, o-
Benzotriazole phenol, o-benzotriazole-p-chlorophenol, o-benzotriazole-
2,4-di-t-butylphenol, o-benzotriazole-2,4-di-t-octylphenol and the like can be mentioned. A hindered phenol compound can also be used as an ultraviolet absorber, and specifically, a phenol derivative in which at least one of the 2- and 6-positions is substituted with a branched alkyl group is preferable.

Further, a benzotriazole-based UV absorber, a salicylic acid-based UV absorber, a cyanoacrylate-based UV absorber, an oxalic acid anilide-based UV absorber, and the like can also be used. For example, JP-A-47-1053
No. 7, No. 58-111942, No. 58-212844
Nos. 59-19945, 59-46646, 59-109055, 63-53544, JP-B-36-10466, 42-26187, and 48-
No. 30492, No. 48-31255, No. 48-415
No. 72, No. 48-54965, No. 50-10726
Nos. 2,719,086 and 3,707,
No. 375, No. 3,754,919, No. 4,220,7
No. 11, etc.

A fluorescent whitening agent can also be used as an ultraviolet absorber, for example, a coumarin fluorescent whitening agent. Specifically, Japanese Patent Publication Nos. 45-4699 and 54-5324
No. etc.

Examples of the antioxidant include EP-A-223239, EP-A-309401, JP-A-309402, JP-A-310551, and JP-A-31551.
Nos. 0552 and 594416, German Patent No. 3435443, and JP-A-54-48535.
JP-A-60-107384 and JP-A-60-107384
No. 383, No. 60-125470, No. 60-125
No. 125471, No. 60-125472, No. 60-287485, No. 60-287486, No. 60-287487, No. 60-28748.
No. 8, No. 61-160287, No. 61-18
Nos. 5483, 61-211079 and 62
-146678, 62-146680,
JP-A-62-146679, JP-A-62-282885, JP-A-62-262047, and JP-A-63-0511
Nos. 74, 63-89877 and 63-88
Nos. 380, 66-88381, 63-1
No. 13536,

Nos. 63-163351 and 63-2
03372, 63-224989, 6
JP-A-3-251282, JP-A-63-267594, JP-A-63-182484, JP-A-1-23992
No. 82, JP-A-2-262654, JP-A-2-7
No. 1262, No. 3-121449, No. 4-2
Nos. 91686, 4-291684, 5-
Nos. 61166, 5-119449, 5-
188687, 5-18886, 5
No. 110490, No. 5-1108437,
No. 5-170361, JP-B-48-43295, JP-B-48-33212, U.S. Pat.
No. 262, No. 4,980,275 and the like.

Specifically, 6-ethoxy-1-phenyl-2,2,4-trimethyl-1,2-dihydroquinoline, 6-ethoxy-1-octyl-2,2,4-trimethyl-1,2 -Dihydroquinoline, 6-ethoxy-1-
Phenyl-2,2,4-trimethyl-1,2,3,4-
Tetrahydroquinoline, 6-ethoxy-1-octyl-
2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline, nickel cyclohexanoate, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) -2 -Ethyl hexane, 2
-Methyl-4-methoxy-diphenylamine, 1-methyl-2-phenylindole and the like.

The lightfastness improvers may be used alone or in combination of two or more. The lightfastness improver may be made water-soluble, dispersed, or emulsified, or may be contained in microcapsules. The addition amount of the light resistance improver is preferably 0.01 to 10% by weight of the coating material for the colorant receiving layer.

Further, for the purpose of enhancing the dispersibility of the inorganic pigment fine particles, various inorganic salts and acids or alkalis as pH adjusters may be contained. Furthermore, various surfactants are used for the purpose of improving the suitability for application and surface quality, and surfactants having ionic conductivity and metal oxide fine particles having electronic conductivity are used for the purpose of suppressing frictional charging and peeling charging of the surface. In addition, various matting agents may be included for the purpose of reducing the friction characteristics of the surface.

(Substrate) As the substrate, any of a transparent substrate made of a transparent material such as plastic and an opaque substrate made of an opaque material such as paper can be used. In order to utilize the transparency of the colorant receiving layer, it is preferable to use a transparent substrate or a high gloss opaque substrate.

The materials usable for the transparent substrate include:
A material having transparency and a property capable of withstanding radiant heat when used in an OHP or a backlight display is preferable. Examples of the material include polyesters such as polyethylene terephthalate (PET); polysulfone, polyphenylene oxide, polyimide, polycarbonate, polyamide and the like. Among them, polyesters are preferred, and polyethylene terephthalate is particularly preferred. The thickness of the transparent substrate is not particularly limited, but is preferably 50 to 200 μm from the viewpoint of handleability.

As the high gloss opaque substrate, those having a surface on the side on which the color material receiving layer is provided having a gloss of 40% or more are preferable. The glossiness is in accordance with JIS P-8142
(75 degree specular gloss test method of paper and paperboard) It is a value obtained according to the method described in. Specifically, the following substrates are mentioned.

For example, a high-gloss paper substrate such as art paper, coated paper, cast-coated paper, baryta paper used for a silver halide photographic support, etc .; polyethylene terephthalate (P
Polyesters such as ET), cellulose esters such as nitrocellulose, cellulose acetate, cellulose acetate butyrate, and plastic films such as polysulfone, polyphenylene oxide, polyimide, polycarbonate, and polyamide are made opaque by containing a white pigment and the like. A calendering treatment may be applied.) High gloss film;
Examples of the substrate include a transparent substrate or a substrate provided with a coating layer of a polyolefin containing or not containing a white pigment on a surface of a high gloss film containing a white pigment or the like. Further, a white pigment-containing foamed polyester film (for example, foamed PET containing polyolefin fine particles and having voids formed by stretching) can also be suitably mentioned.

The thickness of the opaque substrate is not particularly limited, but is preferably 50 to 300 μm from the viewpoint of handleability.

The substrate may be subjected to a corona discharge treatment, a glow discharge treatment, a flame treatment, an ultraviolet irradiation treatment or the like.

Next, the base paper used for the paper substrate will be described in detail. The base paper is made from wood pulp as a main raw material, and if necessary, in addition to wood pulp, using synthetic pulp such as polypropylene or synthetic fiber such as nylon or polyester. As the wood pulp, LBKP, LBSP, NBKP, NBSP, LD
Any of P, NDP, LUKP, and NUKP can be used, but LBKP, NBSP, LB containing a large amount of short fibers
It is preferable to use more of SP, NDP and LDP. However, as the ratio of LBSP and / or LDP,
It is preferably from 10% by weight to 70% by weight.

As the pulp, a chemical pulp containing less impurities (sulfate pulp or sulfite pulp) is preferably used.
Pulp that has been subjected to bleaching treatment to improve whiteness is also useful.

In the base paper, sizing agents such as higher fatty acids and alkyl ketene dimers, white pigments such as calcium carbonate, talc and titanium oxide, paper strength agents such as starch, polyacrylamide and polyvinyl alcohol, fluorescent whitening agents, Water retention agents such as polyethylene glycols, dispersants, and softening agents such as quaternary ammonium can be appropriately added.

The freeness of pulp used for papermaking is as follows:
200 to 500 ml is preferable according to the rules of CSF, and
The fiber length after beating is preferably 30 to 70% as a sum of 24 mesh residual weight% and 42 mesh weight% specified in JIS P-8207. In addition, it is preferable that the weight% of the 4 mesh residue is 20% by weight or less.

The basis weight of the base paper is preferably 30 to 250 g, particularly preferably 50 to 200 g. The thickness of the base paper is preferably from 40 to 250 μm. The base paper may be calendered at the papermaking stage or after papermaking to provide high smoothness. The base paper density is 0.7 to 1.2 g / m ² (JI
SP-8118) is common. Further, the stiffness of the base paper is set to 20 under the conditions specified in JIS P-8143.
~ 200 g is preferred.

A surface sizing agent may be applied to the surface of the base paper. As the surface sizing agent, the same sizing agent as can be added to the base paper can be used. The pH of the base paper is determined by JI
When measured by the hot water extraction method specified in SP-8113, it is preferably 5 to 9.

The polyethylene covering the front and back surfaces of the base paper is mainly low-density polyethylene (LDPE) and / or
Alternatively, it is a high-density polyethylene (HDPE), but other LLDPE, polypropylene, or the like can be partially used.

In particular, the polyethylene layer on the side on which the color material receiving layer is formed is formed by adding rutile or anatase type titanium oxide to polyethylene, as is widely used in photographic printing paper, to obtain opacity and whiteness. It is preferable to improve the above. Here, the content of titanium oxide is preferably about 3 to 20% by weight, more preferably 4 to 13% by weight, based on polyethylene.

The polyethylene-coated paper may be used as glossy paper, or when a polyethylene is melt-extruded onto the surface of a base paper to perform coating, a so-called embossing process is performed to obtain a matte surface or the like which can be obtained with ordinary photographic printing paper. Those having a silk surface can also be used.

[0106]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. still,
“Parts” and “%” in the examples all represent “parts by weight” and “% by weight”.

-Preparation of Support- Wood pulp consisting of 100 parts of LBKP was subjected to 300 ml of Canadian freeness using a double disc refiner.
Beated until 0.5 part of epoxidized behenamide, 1.0 part of anionic polyacrylamide, 0.1 part of polyamide polyamine epichlorohydrin, and 0.5 part of cationic polyacrylamide were added in absolute weight ratio to pulp. And weighed with a Fourdrinier paper machine to produce a base paper of 170 g / m ² .

To adjust the surface size of the base paper, a fluorescent whitening agent (Whit
ex BB, manufactured by Sumitomo Chemical Co., Ltd.), impregnated in the base paper so as to have an absolute dry weight of 0.5 g / m ² , dried, and then calendered. To obtain a base paper adjusted to a density of 1.05.

After performing corona discharge treatment on the wire surface (back surface) side of the obtained base paper, high-density polyethylene was coated to a thickness of 19 μm using a melt extruder, and a resin layer consisting of a mat surface was formed. (Hereinafter, the resin layer surface is referred to as a “back surface”). This resin layer on the back side is further subjected to corona discharge treatment, and then, as an antistatic agent,
A dispersion obtained by dispersing aluminum oxide (alumina sol 100, manufactured by Nissan Chemical Industries, Ltd.) and silicon dioxide (Snowtex O, manufactured by Nissan Chemical Industries, Ltd.) in water at a ratio (weight ratio) of 1: 2, Coating was performed so that the dry weight was 0.2 g / m ² .

Further, after a corona discharge treatment was applied to the felt surface (surface) on the side where the resin layer was not provided, 10% by weight of anatase type titanium dioxide, a trace amount of ultramarine blue, and 0.01% by weight of a fluorescent whitening agent were used. % (Vs. polyethylene)
A low-density polyethylene having an MFR (melt flow rate) of 3.8 is melt-extruded to a thickness of 29 μm using a melt extruder to form a high-gloss thermoplastic resin layer on the surface side of the base paper (hereinafter, referred to as This high gloss surface is referred to as a “back surface”.)

(Examples 1 to 3) The following compositions were mixed with and mixed with a high-speed rotating colloid mill (CLEARMIX, manufactured by M Technique Co., Ltd.) at a rotation speed of 10:
After dispersion at 000 rpm for 20 minutes, a 9% aqueous solution of polyvinyl alcohol was added, and the mixture was further dispersed under the same conditions as above to prepare coating materials (1) to (3) for colorant receiving layer. Weight ratio of silica fine particles to water-soluble resin (PB ratio /
:) was 3.5: 1.

[Composition of Colorant Receptive Layer Coating Solutions (1) to (3)] Silica Fine Particles: 9.9 parts (average primary particle diameter: 7 nm; Aerosil 300, manufactured by Nippon Aerosil Co., Ltd.) 20% aqueous mordant (Type of mordant: see Table 1 below) 10.7 parts Ion-exchanged water 67.2 parts 9% aqueous solution of polyvinyl alcohol (water-soluble resin) 31.4 parts (PVA420, Inc.) Kuraray, saponification degree 81.8%, polymerization degree 2000)

-Preparation of Ink-Jet Recording Sheet- For each of the colorant receiving layer coating liquids (1) to (3) obtained above, three kinds of the ink-jet recording sheet (1) of the present invention were prepared by the following procedure. To (3). Less than,
The coating material (1) for the colorant receiving layer will be described as an example. The colorant receiving layer coating solution (1) is applied on the glossy surface of the support at an application amount of 200 cc / m ² using an extrusion die coater (coating step), and is heated to 80 ° C. with a hot air drier. The coating layer was dried at a wind speed of 3 to 8 m / sec until the solid content concentration of the coating layer became 20%. The coating layer exhibited a constant rate of drying during this period. Immediately thereafter, 3 parts of a crosslinking agent solution (1) having the following composition were added.
The coating layer was immersed for 0 ^second to deposit 20 g / m ² on the coating layer (step of applying a crosslinking agent solution), and further dried at 80 ° C. for 10 minutes (drying step). As a result, an ink jet recording sheet (1) of the present invention was prepared, in which a color material receiving layer having a dry film thickness of 32 μm was provided on the high gloss surface of the support.
Next, the same operation was performed for the colorant receiving layer coating solutions (2) and (3).

[Composition of Crosslinking Agent Solution (1)] Borax 6% 25 parts Surfactant 10% aqueous solution 2 parts (F-144D, manufactured by Dainippon Ink and Chemicals, Inc.) Ion-exchanged water・ ・ ・ 68.3 parts Polyallylamine 20% aqueous solution ・ ・ ・ 3 parts (Mordant, molecular weight 5000) Polyfix 700 ・ ・ ・ 1.7 parts (Mordant, manufactured by Showa Polymer Co., Ltd.)

Comparative Example 1 The cross-linking agent solution (1) used in Example 2 did not contain two mordants (in the composition of the cross-linking agent solution (1)), and other A crosslinking agent solution (2) was prepared in the same manner as in 1). Then, in the same manner as in Example 2 except that the crosslinking agent solution (2) was used in place of the crosslinking agent solution (1) used in Example 2, the inkjet recording sheet (4) of Comparative Example was used. Produced.

(Comparative Example 2) The same procedure as in Example 1 was carried out except that the 20% aqueous mordant used in the preparation of the coating material for the colorant receiving layer in Example 1 was not used. Sheet (5) was produced.

Comparative Example 3 As a mordant used in the preparation of the coating material for the colorant receiving layer in Example 1, a copolymer of trimethyl-p-vinylbenzylammonium chloride / ethyl methacrylate (copolymerization ratio (mol% ) = 50/50; molecular weight 15,000) and the copolymerization ratio (mol%) is 10/50.
When a coating material for a colorant receiving layer was prepared in the same manner as in Example 1 except that a copolymer having a molecular weight of 90 (19000) was used, the mordant itself coagulated and was uniformly mixed with silica. Could not.

(Examples 4-9, Comparative Examples 4-5) Example 2
In the colorant receiving layer coating solution and the crosslinking agent solution
Ratio (cp ¹/ Cp^Two; Usage rate, coating amount (g / m^Two))
Examples as shown in Table 2 below, except for each change
2. Ink-jet recording sheet of the present invention in the same manner as in 2.
(6) to (11) and for inkjet recording of Comparative Example
Sheets (12) to (13) were produced. In addition, the color material receiving layer
And the type of mordant used in the crosslinking agent solution was the same as in Example 2.
Mordant applied from the colorant receiving layer coating solution
Amount (cp¹) And two media introduced from the crosslinking agent solution (1)
Total application amount of dye (and) (cp^Two) And
The proportions of the various mordants and their use have not changed.

<Evaluation of Performance> The inkjet recording sheets (1) to (3) and (6) to (1) of the present invention obtained from the above.
1) and a sheet for inkjet recording (4) of a comparative example
For each of (5) and (12) to (13),
The following evaluation was performed. The evaluation results are shown in Table 1 below. (Glossiness) The 60 ° glossiness on the surface of the colorant receiving layer of the recording sheet before printing was measured using a digital variable-angle glossmeter (UGV-
50DP, manufactured by Suga Test Instruments Co., Ltd.).

(Ink absorption speed) Using an ink jet printer (PM-770C, manufactured by Seiko Epson Corporation), Y (yellow), M (magenta), C (cyan) were formed on the color material receiving layer of each recording sheet. , K (black), B (blue), G
(Green) and R (red) solid images are printed, and then
(After 0 seconds), paper was contact-pressed on the image, and the degree of transfer of the ink to the paper was evaluated according to the following criteria. The absence of ink transfer indicates that the ink absorption rate is good. [Criterion] AA: Transfer of ink onto paper was not recognized. CC: Partial transfer of ink on paper was observed.

(Cracks of Coloring Material Receiving Layer) The surface condition of the coloring material receiving layer of each ink jet recording sheet was visually observed, and the presence or absence of cracks on the surface and the size thereof were evaluated according to the following criteria. [Criterion] AA: Cracks were not observed at all and were good. BB: Cracks having a length of about 1 to 2 mm were observed. CC: Cracks having a length of 3 mm or more were remarkably observed.

(Waterfastness) Y (yellow), M (magenta), C (cyan),
Solid images of K (black), B (blue), G (green), and R (red) were printed, left for 3 hours, immersed in water for 1 minute, and visually checked for the degree of outflow of the ink into the water. It was evaluated according to the standard. [Criterion] AA: No outflow of dye was observed. BB: Dye outflow was observed throughout, and the color density of the image gradually decreased. CC: The dye has almost completely flowed into the water.

(Bleeding over time) A grid-like linear pattern (line width: 0.28 mm) in which magenta ink and black ink were adjacent to each other was printed on each ink jet recording sheet using the same printer as used for measuring the ink absorption rate. Printed.
After leaving for 3 hours after printing, it was stored in a thermo-hygrostat at 40 ° C. and 90% RH for 3 days, and the line width of the black portion was measured and evaluated according to the following criteria. [Criterion] AA: The occurrence of bleeding over time was hardly recognized, and was good. (Line width: 0.28 to 0.30 mm) BB: Slight bleeding over time was recognized, but at a level that was not problematic in practical use. (Line width: 0.31 to 0.35 mm) CC: Bleeding over time was remarkably observed, which was at a level that was problematic in practical use. (Line width: 0.35 mm or more)

(Image Density) A black solid image was printed on a recording sheet by using the same printer as that used for the measurement of the ink absorption speed, and the X-Rite310TR was printed.
(Manufactured by X-Rite) to measure the reflection density.

[0125]

[Table 1]

[0126]

[Table 2]

From the results shown in Table 1, the glossiness of the inkjet recording sheets (1) to (3) and (6) to (11) containing the mordant in both the coating material for the colorant receiving layer and the crosslinking agent solution was high. In addition, it exhibited sufficient water resistance and bleeding resistance over time, and was able to form a more vivid, clear, and high-saturation image without blemishes. Further, the image density could be further improved. On the other hand, in the inkjet recording sheet (5) in which the coating material for the colorant receiving layer did not contain the mordant, although the glossiness was obtained, sufficient water resistance and bleeding resistance over time were not obtained, and the image density was poor. I was Further, in the ink jet recording sheet (4) in which the mordant was not supplied by applying the crosslinking agent solution after the application, the gloss was low and the water resistance was low despite the addition of the mordant in the coating material for the colorant receiving layer. Inferiority and bleeding resistance over time, and no improvement in image density was observed.

Further, from the results in Table 2 above, even when the mordant is contained in both the coating material for the colorant receiving layer and the solution of the crosslinking agent, the ink jet recording sheet having a small amount of the mordant introduced from the coating solution for the colorant receiving layer. In (12), an ink jet recording sheet having a low ink absorption rate, poor water resistance and poor bleeding resistance over time, and having a small amount of mordant introduced from the crosslinking agent solution compared to the amount introduced from the colorant receiving layer coating solution ( 1
In the case of 3), it was not possible to form an image with high chroma due to dark spots and bleeding over time due to penetration into the layer. Moreover, in each case, the improvement in image density was inferior. Further, as in Comparative Example 3, a mordant containing a main copolymerization component other than the above-described mordant monomer was inferior in compatibility and could not avoid aggregation during preparation.

[0129]

According to the present invention, the bleeding resistance after printing, the water resistance and the glossiness are extremely excellent, the color purity and the color density are excellent without blurring. The inkjet recording sheet which can form an inkjet image with extremely high saturation, such as a higher inkjet recording sheet, can be provided. Moreover, it is possible to form a high-resolution image which is strong without cracks, has good ink absorption, and has high light resistance even under irradiation with light such as sunlight or a fluorescent lamp.

Claims (5)

[Claims] 1. An ink jet recording sheet having a color material receiving layer on at least one surface of a substrate, wherein the color material receiving layer contains inorganic pigment fine particles having an average primary particle diameter of 20 nm or less, a water-soluble resin, and a mordant. A colorant receiving layer coating solution to be applied, and simultaneously with the coating, or during the drying of the formed coating layer, before the coating layer exhibits a reduced drying rate, the water-soluble After applying a solution containing a cross-linking agent capable of cross-linking a resin and a mordant, the applied layer obtained by applying the solution is cross-linked and cured, and the amount of the mordant introduced from the colorant receiving layer coating solution is applied. (cp ¹⁾
And the coating amount ratio (cp ¹ : cp ² ; weight) of the mordant introduced from the solution containing the crosslinking agent and the mordant (cp ² )
Is 30: 1 to 1:30. 2. The mordant contained in the colorant receiving layer coating solution,
Consisting of a copolymer of a mordant monomer and a non-mordant monomer,
The ink jet recording sheet according to claim 1, wherein the copolymerization ratio of the mordant monomer in the copolymer is 30 mol% or more. 3. The colorant receiving layer has a three-dimensional network structure with a porosity of 50 to 80%, and a content (i: p / weight ratio) of the inorganic pigment fine particles (i) and the water-soluble resin (p). ) Is 1.5: 1 to 1
The inkjet recording sheet according to claim 1, wherein the ratio is 10: 1. 4. The ink-jet recording sheet according to claim 1, wherein the inorganic pigment fine particles are silica having ^{2 to} 3 silanol groups per nm ^{2 of} the surface thereof. 5. The ink jet recording sheet according to claim 1, wherein the crosslinking agent is boric acid or a boron compound.