JP3244944B2 - Recording medium, inkjet recording method using the same, printed matter, dispersion, and method for manufacturing recording medium using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium suitable for recording using an aqueous ink, an ink jet recording method and a printed matter using the recording medium, and particularly relates to an image density,
High resolution, clear color tone, excellent ink absorption ability,
The present invention relates to a recording medium having no color change and excellent color reproducibility, an ink jet recording method using the same, and a printed matter.

The present invention also relates to a dispersion suitable for producing the recording medium and a method for producing a recording medium using the dispersion.

[0003]

2. Description of the Related Art In recent years, an ink jet recording system records fine images of ink and characters by causing fine droplets of ink to fly according to various operating principles and adhere to a recording medium such as paper. It has features such as high speed, low noise, easy multi-coloring, great flexibility in recording patterns, and no need for development and fixing, and is rapidly spreading in various applications such as information equipment as various image recording apparatuses. Furthermore, images formed by the multi-color ink jet method can obtain multicolor printing by the plate-making method or a record comparable to printing by the color photographic method. Since it is cheaper than multicolor printing and printing, it is being widely applied to the field of full-color image recording. Recording devices and recording methods have been improved in line with improvements in recording characteristics such as higher recording speed, higher definition, and full color printing. It has become.

Conventionally, various types of recording media have been proposed. For example, Japanese Patent Application Laid-Open No. 52-53012 discloses an ink jet paper in which a low-size base paper is impregnated with a paint for surface treatment. JP-A-53-4911
No. 3 discloses an inkjet paper in which a sheet containing a urea-formalin resin powder is impregnated with a water-soluble polymer. JP-A-55-5830 discloses an ink-jet recording sheet provided with an ink-absorbing coating layer on the surface of a support, and JP-A-55-51583 discloses an amorphous recording medium as a pigment in a coating layer. An example using silica is disclosed, and JP-A-55-146786 discloses an example using a water-soluble polymer coating layer.

In recent years, a recording medium having a coating layer using an alumina hydrate having a boehmite structure has been proposed. For example, US Pat. No. 4,879,166 and US Pat.
104730, JP-A-2-276670, 4
Nos. 37576 and 5-32037.

A recording medium using these alumina hydrates has a good fixation of a dye in ink and a good color image because the alumina hydrate has a positive charge. There are no problems such as browning of the black ink and light fastness caused by using the silica compound, and further, it is preferable to a conventional recording medium in terms of image quality, particularly in terms of image quality in a full-color image. . However, in order to sufficiently exhibit the advantages of the alumina hydrate in a recording medium, the following problems need to be improved.

1) Since coating becomes difficult due to the time-dependent increase in viscosity of the dispersion containing alumina hydrate, there is a problem that the solid content concentration of the liquid cannot be increased. Japanese Patent Application Laid-Open No. 4-67986 discloses a method for lowering the degree of polymerization of a binder polymer. However, there are problems such as poor appearance such as cracking of an ink receiving layer and a decrease in water resistance, and sufficient improvements have been made. Absent.

2) There is a problem that the solid content cannot be increased because the viscosity of the dispersion containing alumina hydrate is high. Japanese Patent Application Laid-Open No. 4-67985 discloses a method of adding an acid such as monocarboxylic acid as a dispersant, but causes production problems such as generation of pungent odor and corrosion. .

3) In order to improve the ink absorbency and the resolution of an image, US Pat. No. 5,104,730, JP-B-3-72460 and JP-A-4-37576 disclose an ink-receiving layer having two layers. A method of making a layer or multi-layer configuration is disclosed. However, the coating / drying of the ink receiving layer is performed twice and the number of steps is increased, and the physical properties of the respective layers are different. There is also a problem in that each layer is separated and peeled off at a portion where is adhered.

4) The present inventors have studied the above-mentioned prior art, and found that the ink absorption and the resolution depend on the thickness of the ink receiving layer, and it is necessary to obtain sufficient ink absorption and resolution. , About 15 μm or more, preferably 2
It was found that a thickness of 0 μm or more was necessary.

It is not easy to efficiently obtain a good ink receiving layer having such a thickness by using the material system in the prior art cited above, ie, a water-soluble polymer binder such as alumina hydrate and polyvinyl alcohol.

For example, there is a method of obtaining a thick ink receiving layer by applying the ink receiving layer many times, but the same problem as in the above 3) occurs. In addition, in the method of obtaining a thick ink receiving layer in one coating, the drying time is long, so the coating speed is extremely slow, productivity is reduced, and the cost is increased. There is a point to be improved that the viscosity of the dispersion increases with time due to the lengthening, and the same problem as 1) described above. Further, a coating machine having a long drying oven may be required. Further, there is a method of performing coating by increasing the solid content concentration of the dispersion liquid.
There is a point 2) to be improved.

5) In order to maintain a good dispersion state, the dispersion of alumina hydrate usually contains several tens of percent of an organic or inorganic acid such as a monocarboxylic acid disclosed in JP-A-4-67985. Has been added. In the ink receiving layer formed from such alumina hydrate, there is a problem that the color of the printed ink changes due to the effect of the acid.

6) There is a method to cope with the above problem 5) by improving the ink. However, it is extremely difficult at present, and a long-term study is required. That is, the inks used in the ink jet recording method are yellow, magenta, cyan, and black. In order to obtain a color image with excellent color reproducibility, the maximum wavelength of each ink is set to an appropriate wavelength region for each color. The molecular structure of many dyes has been designed, but it requires complicated steps and presents problems in terms of condition and yield. Further, when color reproducibility is to be realized by improving dyes, it is often difficult to obtain the maximum color density.

[0015]

The inventors of the present invention have made intensive studies on such a problem, and as a result, it has been found that a color image formed by ink-jet recording is a method in which the dye in the ink printed on the recording medium is applied to the recording medium. On the other hand, since a color image is obtained by dyeing the receiving layer, it has been found that the characteristics of the recording medium largely control the quality of the obtained color image. It has also been found that it is possible to realize excellent color reproducibility by improving the recording medium in the same manner. Even if good colors are obtained for each color by improving the ink, if the colors change depending on the recording medium, a good color image cannot be obtained, and an ink suitable for the recording medium must be produced. In this case, the ink must be changed for each recording medium.
Therefore, a recording medium that faithfully reproduces the color of the ink is most preferable, and therefore, the improvement of the recording medium is necessary for obtaining good color reproducibility.

However, as far as the present inventors know, there are no documents mentioning that the color reproducibility is improved by improving the recording medium.

Accordingly, the present invention has been made to solve the above problems, and has high image density, high resolution, clear color tone, good ink absorption, no change in color, and no color change. An object of the present invention is to provide a recording medium having good reproducibility, an ink jet recording method using the same, and a printed material.

The present invention also provides a dispersion suitable for producing the recording medium and a method for producing a recording medium using the dispersion.

[0019]

Means for Solving the Problems and Effects To solve the above problems, the inventors of the present invention have conducted intensive studies, and as a result, a natural polymer having alumina hydrate as a pigment and gelling ability as a binder has been obtained. The use of a substance or a derivative thereof, particularly a specific alkali-processed gelatin, makes it possible to effectively utilize the sharp sol-gel conversion ability of the alkali-processed gelatin and the thixotropy of the alumina hydrate / alkali-processed gelatin dispersion. Thick ink receiving layer with good productivity,
In addition, it has been found that a recording medium having an ink receiving layer which can be formed stably, has good ink absorption and resolution, and has good color reproducibility at high image density can be obtained. Reached.

That is, according to the present invention, the BET specific surface area is 70 to 3
Alumina hydrate of 100 m ² / g and PAGI method
The weight average molecular weight measured Ri is a recording medium characterized by having an ink-receiving layer containing a Al <br/> potash process gelatin are 100000-5 thousand.

Further, according to the present invention, the BET specific surface area is 70 to 3
Alumina hydrate of 100 m ² / g and PAGI method
The weight average molecular weight measured Ri is a Al <br/> potash process gelatin are 100000-5 thousand dispersed in water, TI value 1.1 to 5.
0 is a dispersion characterized by being 0.

According to the present invention, there is further provided an ink jet recording method in which a small droplet of ink is ejected from a fine hole and applied to a recording medium to perform printing, wherein the recording medium described above is used. It is.

Further, the present invention relates to an ink jet method in which a small droplet of ink is ejected from a fine hole and applied to a recording medium to perform printing, wherein the recording medium described above is used as the recording medium.
Using a recording medium, assuming that the recording medium contains alkaline gelatin on the surface, the maximum absorption wavelength of the ink is λ1, and the maximum absorption wavelength of the printing portion of the recording medium printed with the ink is λ2, | λ1 -Λ2 | ≦ 30 nm.

Further, the present invention provides an ink jet printing method using an ink dot .
The printed matter printed on the recording medium described above, which contains an alkali-processed gelatin on the surface and has a gloss Gs1 (60) of a non-printed portion and a gloss Gs2 (Glossary of a printed portion) measured by JIS Z8741. 60) is 40 or more.

Further, the present invention provides the above-described ink dots.
The printed matter printed on the recording medium according to the above item, wherein the surface contains an alkali method gelatin, and the glossiness Gs1 (6) of the non-printed portion is measured by a method specified in JIS Z8741.
0) and the glossiness Gs2 (60) of the printed portion satisfy the relationship of | Gs1 (60) −Gs2 (60) | ≦ 20.

Hereinafter, preferred embodiments of the present invention will be described.

As shown in FIG. 1, the recording medium of the present invention has a structure in which an ink receiving layer mainly composed of alumina hydrate as a pigment and a binder is formed on a substrate.
Since alumina hydrate has a positive charge, the dye in the ink is well fixed, and an image with good color development can be obtained. Conventionally,
Since there is no problem such as browning and light fastness of the black ink caused by using the silica-based compound, it is the most preferable material for the ink receiving layer.

The binder used in the present invention includes:
A water-soluble polymer substance having a gel-forming ability (a property of gelling into a jelly-like form by cooling an aqueous solution (sol) thereof) and capable of being crosslinked by a hardener is used, particularly gelatin, agar, and alginic acid. Sodium, kappa-carrageenan, lambda carrageenan, iota carrageenan, furceleran and the like. In particular, gelatin is preferable because the aqueous solution can perform sol-gel conversion sharply by a change in temperature.

Due to this sol-gel conversion ability (setting property) of gelatin, an ink receiving layer having a good thickness can be formed with high productivity. When a normal water-soluble polymer having no gel-forming ability, for example, polyvinyl alcohol, is used as the binder, the leveling and dropping occur as described above, so that it is not easy to obtain an ink receiving layer having a thickness of 15 to 20 μm or more. Gelatin is also preferable from the viewpoint of safety and the like.

A conventional example in which gelatin is used in an ink receiving layer of an ink jet recording sheet is disclosed in JP-A-5-16.
517, Japanese Patent Publication No. 3-72460,
-289375, U.S. Patent No. 188048
However, gelatin has only the function of absorbing the ink solvent, and is essentially different from the function of the gelatin used in the present invention.

The gelatin preferably used in the present invention is produced by a lime treatment in a process of producing collagen (ossein) from a pig skin, a bovine bone or the like as a raw material and having undergone a decalcification step. It is called gelatin or alkali-treated gelatin.

Here, the alkali-processed gelatin used in the present invention is a low-molecular-weight alkali-processed gelatin obtained by hydrolyzing or enzymatically degrading the alkali-processed gelatin produced by the above-mentioned process in addition to the alkali-processed gelatin produced by the above-mentioned process. Or phthalated gelatin, acylated gelatin,
Phenylcarbamylated gelatin, acetylated gelatin,
Also included are alkali-processed gelatins that have been chemically modified, such as succinated gelatin and carboxy-modified gelatin.

Further, as a result of diligent studies by the present inventors on the above-mentioned alkaline method gelatin, it has been found that the above-mentioned alkaline gelatin has good compatibility with alumina hydrate described later and can form a good ink receiving layer suitable for an ink jet recording method. It has been found that alkali-processed gelatin having physical properties such as a specific range of molecular weight is particularly preferable. As far as the present inventors know, there is no example showing the range of physical properties of compatible gelatin suitable as a binder for a specific alumina hydrate. The physical properties of the gelatin preferably used in the present invention are listed and described below.

1) Weight average molecular weight, number average molecular weight It can be determined by liquid chromatography, and the weight average molecular weight (Mw) is preferably from 100,000 to 5,000.
95,000 to 7,000 is preferred. Number average molecular weight (Mn) is 6
It is preferably from 55,000 to 5,000, more preferably from 50,000 to 8,000.
Further, the ratio of the weight average molecular weight to the number average molecular weight (Mw / M
n) is preferably from 0.5 to 3.0, more preferably from 0.6 to 2.7.

If it exceeds the above range, the viscosity of the alumina hydrate / alkali method gelatin solution becomes high, so that it is necessary to devise a coating method and precipitation of insoluble matter may be observed. Also,
Below this range, gelatin is not gelled, or even if it is gelled, it is very soft and almost liquid, so that the liquid will level and fall off, and some contrivance is required to form a thick ink receiving layer. Furthermore, since the film property is low, there is a tendency that cracks are easily generated before and / or after printing.

2) Jelly strength The strength can be measured using a jelly tester, and the strength is preferably from 300 to 1, more preferably from 250 to 1, more preferably from 200 to 2.

If it exceeds this range, the viscosity of the alumina hydrate / alkali method gelatin solution becomes extremely high, so that it is necessary to devise coating and precipitation of insolubles is observed.
Below this range, gelatin does not gel in a jelly state, or is very soft and almost liquid even if it gels in a jelly state, so the liquid leveled out and was devised to form a thick ink receiving layer. Cost.

3) pH value, isoionic point The pH value is measured with a pH meter and is 4.5 to 7.0.
0 is preferable, and 4.8 to 6.8 is more preferable. The isoionic point is measured using a pH meter after passing through a cation exchange resin / anion exchange resin, and is preferably 4.1 to 6.0, and more preferably 4.5 to 5.5.

The relationship between the pH and the isoionic point is preferably pH value ≧ (isoionic point−0.1).

When this relationship is not satisfied, the stability of the gelatin solution is reduced, the hydrolysis of the gelatin progresses with time, and the physical properties of the alumina hydrate / alkali gelatin mixed dispersion have a certain value, For example, it becomes difficult to obtain a constant viscosity, and the physical properties of the ink receiving layer obtained by coating and drying, for example, the thickness, the pore radius, and the pore volume change, so that it becomes difficult to obtain a stable ink receiving layer. .

Here, the physical property values of the above 1) to 3) are determined by the PAGI method (Testing method for photographic gelatin, 1992).
The measurement is performed by the method specified in (1), and the details will be described in Examples described later.

4) Swelling Ratio The swelling ratio in the present invention is calculated by (weight of swollen solvent / weight of alkali-processed gelatin) × 100 (details will be described in Examples).
Alkali-processed gelatin of 500% or more, preferably 500 to 5000%, more preferably 700 to 4000% can be used. In addition, alkali-processed gelatin having a swelling ratio to ethylene glycol of 300 to 2000%, more preferably 400 to 1500% is preferable.

The ink for ink-jet printing comprises a dye and a solvent. Most of the solvent is water, but usually contains a small amount of a high-boiling solvent. For example, polyhydric alcohols such as ethylene glycol and diethylene glycol are used. Will be

Conventionally, as an ink receiving layer of a recording medium,
It is known that water-absorbing resins are used, but they show sufficient absorption and swelling with water, but have very low absorption and swelling with ethylene glycol. The alkali method gelatin used in the present invention exhibits good absorbability and swelling properties with respect to both water and ethylene glycol. In the present invention, the alkali method gelatin absorbs ink at the same time as the pores of alumina described later. It has the effect of contributing to the performance.

5) Zeta potential The surface potential of alkali-processed gelatin can be generally determined by a zeta potential measuring device, and the zeta potential of a 0.1% solution is preferably 0 mV or less.

Below this range, although the reason is not clear, the viscosity of the alumina hydrate / alkali method gelatin solution becomes extremely high, so that the coating may need to be devised or insoluble matter may be precipitated. .

The above-mentioned specific alkaline method gelatin may be used alone or in combination of two or more.
Further, acidic gelatin may be used in combination.

Further, gelatin having a weight-average molecular weight of less than 5,000 or various water-soluble high-molecular substances may be used in combination in terms of viscosity adjustment, adhesion improvement, and film strength improvement. The amount is
It is only necessary to be within a range that does not hinder the formation of a good ink receiving layer, and it cannot be said unconditionally because it varies depending on conditions such as the type of the substance to be used.
It is about 5%.

Specific examples of the water-soluble polymer substance which can be used in combination are, for example, a natural polymer substance, starch, oxidized starch, starch acetate, amine starch, carboxy starch, dialdehyde starch, cationic starch, dextrin, Casein, bullran, dextran, methylcellulose, ethylcellulose, propylcellulose, ethylmethylcellulose, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, gum arabic, trangacanth gum, karaya gum, echo gum, roast bean gum, albumin, chitin, saccharides, etc. Polymer substance or derivative thereof; polyvinyl alcohol, cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, silanol-modified Polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl pyridinium, polyvinyl imidazole, vinyl polymer or a derivative thereof, such as polyvinyl pyrazole; polyacrylamide, dimethylaminoethyl acrylate, polyacrylic acid or salts thereof, acrylic acid - methacrylic acid copolymer or a salt thereof,
Acrylic group-containing polymers such as polymethacrylic acid or a salt thereof, acrylic acid-vinyl alcohol copolymer or a salt thereof; latexes such as SBR latex, NBR latex, methyl methacrylate-butadiene copolymer, ethylene-vinyl acetate copolymer A polyethylene glycol, a polypropylene glycol, a polyethylene imine, a maleic anhydride or a copolymer thereof, and the like, and one or more of these may be used in combination with an alkali-process gelatin.

The mixing ratio of the alumina hydrate and the binder containing the alkali method gelatin was 1: 1 to 30: 1 by weight,
More preferably, it can be arbitrarily selected from the range of 5: 1 to 25: 1. When the amount of the binder is less than the above range, the mechanical strength of the ink receiving layer is insufficient, and cracks and powder fall easily occur.When the amount exceeds the above range, the pore volume is reduced and the ink absorbency is reduced. It tends to decrease.

The alkali-processed gelatin used in the present invention can be hardened with a hardener, and by hardening, the water resistance of the ink receiving layer can be improved. Specific examples of the hardener include aldehyde compounds such as formaldehyde, glyoxal, and glutaraldehyde; ketone compounds such as diacetyl and cyclopentanedione; bis (2-chloroethylurea)-
Active halogen compounds such as 2-hydroxy-4,6-dichloro-1,3,5-triazine, 2,4-dichloro-6-S-triazine sodium salt; divinylsulfonic acid, 1,3-vinylsulfonyl-2 -Propanol,
N, N'-ethylenebis (vinylsulfonylacetamide), 1,3,5-triacryloyl-hexahydro-
Active vinyl compounds such as S-triazine; N-methylol compounds such as dimethylol urea and methylol dimethylhydantoin; isocyanate compounds such as 1,6-hexamethylene diisocyanate; US Patent No. 3017
Nos. 280 and 29836611; aziridine compounds; carboximide compounds described in U.S. Pat. No. 3,100,704; epoxy compounds such as glycerol triglycidyl ether; 1,6-hexamethylene-N, N ' -Ethylene imino compounds such as bisethylene urea; halogen carboxaldehyde compounds such as mucochloric acid and mucophenoxycyclo acid; 2, 3
A siloxane compound such as dihydroxydioxane;
Inorganic hardeners such as chrome alum, potassium alum, zirconium sulfate and chromium acetate can be mentioned.
They can be used alone or in combination of two or more.

The amount of the hardener to be used is appropriately determined in consideration of the balance between the water resistance of the ink receiving layer and the swelling property of the alkali-processed gelatin. Eluted aluminum ions (not clear) tend to show a hardening effect on alkali-processed gelatin, and it is not always necessary to use it. 0.2 to 20 parts by weight, preferably 0.5 to 15 parts by weight, more preferably 0.7 to 1 part by weight, based on the amount of the alkali method gelatin used.
0 parts by weight.

The alumina hydrate used in the present invention is preferably an alumina hydrate which shows an amorphous state by X-ray diffraction.

The alumina hydrate is defined by the following general formula.

Al ₂ O _3-n (OH) _2n · mH ₂ O In the formula, n represents any one of the integers 0, 1, 2 and 3, and m is 0 to 10, preferably 0 to 5 Represents the value of
m can also be a non-integer value, since mH ₂ O often represents a removable aqueous phase that does not participate in the formation of a crystal lattice. Also, calcining this type of material can lead to a value of m of zero.

Further, as the alumina hydrate used in the present invention, one containing a metal oxide, for example, titanium dioxide may be used. Both properties can be further improved over conventional alumina hydrates.

The content ratio of titanium dioxide is preferably 0.01 to 1.00% by weight of alumina hydrate, more preferably 0.13 to 1.00% by weight. Further, the titanium dioxide preferably has a valence of +4.

According to the knowledge of the present inventor, the titanium dioxide contained on the surface of the alumina hydrate is FE-TE
In observation with a magnification of 500,000 times of M (Hitachi, HF2000), it exists as ultrafine particles that are so small that it cannot be observed, and functions as an adsorption point when adsorbing the dye in the ink.

Although the reason is not clear, YANG et al. (React. Kinet. Catal. Lett.,
46 [1], 179-186, 1992), the addition of titanium dioxide generates a twisted site containing Al ₃ ⁺ having a strong electron-accepting property to improve the adsorptivity, or It is speculated that the titanium ion of titanium and the dye form a coordination bond. Further, according to the findings of the present inventor, since this titanium dioxide has a valence of +4, it does not interact with alumina hydrate. As a result, titanium dioxide is present without affecting the charge on the surface of the alumina hydrate under the conditions of both the particle diameter and the valence, and the dispersibility of the alumina hydrate is not impaired. When the content of titanium dioxide is smaller than the above range, the improvement of the dye adsorbability in the ink is not remarkable, and when the content is larger than the above range, the surface charge of the alumina hydrate decreases and the dispersibility decreases. Tend to.

When the valence of titanium is less than +4, the titanium dioxide acts as a catalyst by light irradiation, the binder is deteriorated, and cracks and powder fall easily occur. Titanium dioxide may be contained only in the vicinity of the surface of the alumina hydrate or may be contained up to the inside. Further, the content may change from the surface to the inside. It is more preferable that titanium dioxide is contained only in the vicinity of the surface, because the properties of the bulk inside the alumina hydrate are easily maintained in the vicinity of the surface, so that the dispersibility does not change.

Instead of titanium dioxide, magnesium,
Calcium, strontium, barium, zinc, boron,
Silicon, germanium, tin, lead, zirconium, indium, phosphorus, vanadium, niobium, tantalum, chromium,
Molybdenum, tungsten, manganese, iron, cobalt,
Although an oxide such as nickel or ruthenium can be used, titanium dioxide is most preferable from the viewpoint of the adsorptivity and dispersibility of the dye in the ink. Although the above metal oxides are often colored, titanium dioxide is colorless and is therefore preferable from this point.

As the alumina hydrate containing titanium dioxide, an alumina hydrate showing an amorphous structure by X-ray diffraction as described above is preferable. The alumina hydrate of the present invention contains titanium dioxide while maintaining this amorphous structure.

The alumina hydrate can be produced by a known method such as hydrolysis of aluminum alkoxide and hydrolysis of sodium aluminate. Rosek et al. (C
collect. Czech. Chem. Commu
n. 56, 1253-1262, 1991) report that the porous structure of alumina hydrate is affected by deposition temperature, solution pH, aging time, and surfactant.

As a method of producing alumina hydrate containing titanium dioxide, a method of producing by hydrolyzing a mixed solution of aluminum alkoxide and titanium alkoxide includes:
This is most preferable because the particle diameter of titanium dioxide is small and controllable. The particle diameter and shape in this method can be determined by, for example, the Society of Societies Publishing Center, Surface Science (ed. By Kenji Tamaru), 1
P. 327 of 985, Ni / A by alkoxide method
It is being studied with l ₂ O ₃ catalysts. As another method, it can be produced by adding alumina hydrate as a crystal growth nucleus when hydrolyzing the mixed solution of the aluminum alkoxide and the titanium alkoxide. In this method, titanium dioxide exists only near the surface of the alumina hydrate.

The alumina hydrate used in the present invention (hereinafter referred to as “alumina hydrate” also includes titanium dioxide-containing alumina hydrate) has a columnar shape, an aspect ratio of 3 or less, and is oriented in a certain direction to form a bundle. It is preferable to use a body-forming material or a flat plate having an average aspect ratio of 3 to 10 and an aspect ratio of a flat plate surface of 0.6 to 1.0, and a flat plate-shaped alumina hydrate is particularly preferable.

The aspect ratio is defined in Japanese Patent Publication No. 5-1601.
It can be determined by the method described in Japanese Patent Publication No.
The aspect ratio is indicated by the ratio of “diameter” to “thickness” of the particle. Here, the “diameter” indicates the diameter of a circle having an area equal to the projected area of the particles when the alumina hydrate is observed with a microscope or an electron microscope. The aspect ratio is the ratio of the diameter indicating the minimum value of the flat surface to the diameter indicating the maximum value when observed in the same manner as the aspect ratio. The average aspect ratio of the latter alumina hydrate, if smaller than the above range, the pore size distribution range of the ink receiving layer becomes narrower,
When it is large, it becomes difficult to produce alumina hydrate with a uniform particle diameter. When the average aspect ratio is smaller than the above range, the pore size distribution becomes narrow similarly.

Among the alumina hydrates, pseudo-boehmite includes:
References (Rosek J., et al., Applie.
d Catalysis, Vol. 74, 29-36, 199
It is generally known that there are columnar (ciliform) and other shapes as described in (1 year).

According to the knowledge of the present inventor, among alumina hydrates, those having a columnar shape (ciliform or hair-bundle shape) are densely packed with alumina hydrate particles, so that the alumina hydrate in the ink receiving layer has a high density. The gap between the alumina hydrate particles tends to be narrow. Therefore, the pore diameter tends to be narrower and the pore diameter distribution tends to be narrow, and as a result, beading tends to occur. Here, beading refers to an image in which ink droplets applied to the surface become beaded on the surface of the ink receiving layer because the ink receiving layer is inferior in ink absorbency, and adjacent ink droplets are mixed in color to cause color unevenness. A phenomenon that can be done.

On the other hand, a flat plate has better dispersibility than a columnar shape (a cilia shape or a hair bundle shape), and when an ink receiving layer is formed, the orientation of alumina hydrate particles becomes random. This is more preferable because the pore size distribution becomes wider.

Here, the shape, aspect ratio, aspect ratio and particle size of the alumina hydrate were determined by dispersing the alumina hydrate in ion-exchanged water and dropping it on a collodion membrane to prepare a measurement sample. The sample was observed and determined using a transmission electron microscope (H-500, manufactured by Hitachi, Ltd.).

The BET specific surface area of the alumina hydrate, the pore size distribution, the pore volume, and the isothermal nitrogen adsorption / desorption curve of the alumina hydrate and the ink receiving layer can be simultaneously obtained by a nitrogen adsorption / desorption method. The measurement was carried out by sufficiently heating and degassing the alumina hydrate or the recording medium having the receiving layer formed on the PET film, and then using Autosorb 1 manufactured by Cantachrome. Calculation of BET specific surface area is B
The method of Runauer et al. was used (J. Am. Che.
m. Soc. 60, 309, 1938). Also,
The pore diameter and the pore volume were calculated by the method of Barrett et al. (J. Am. Chem. Soc., 73, 37).
3, 1951).

The BET specific surface area is 70 to 300 m ^2.
/ G is preferred. When the BET specific surface area is larger than the above range, the pore size distribution is shifted to the larger side and the dye in the ink cannot be sufficiently absorbed and fixed, and when the BET specific surface area is smaller, the pigment cannot be coated with good dispersion. It becomes difficult to control the pore size distribution.

An ink receiving layer is formed using the alumina hydrate and the binder. The physical property value of the ink receiving layer is not determined only by the alumina hydrate used, but the type and amount of the binder, the concentration of the coating liquid, the viscosity, the dispersion state,
Coating equipment, coating head, coating amount, dry air flow, temperature,
As it changes depending on various manufacturing conditions such as the blowing direction,
In order to obtain the characteristics of the ink receiving layer according to the present invention, it is necessary to control the production conditions within an optimum range.

In the first preferred embodiment of the present invention, the average pore radius of the ink receiving layer is preferably from 20 to 200 °, and the half width of the pore size distribution is preferably from 20 to 150 °, more preferably from 80 to 150 °. . Here, the half width of the pore diameter distribution indicates the width of the pore radius which is half the frequency of the average pore radius. When the average pore radius is larger than the above range, the adsorption and fixation of the dye in the ink is reduced, and bleeding is likely to occur in the image. When the average pore radius is smaller, the absorption of the ink is reduced and beading is reduced. It is easy to occur. When the half width is out of the above range, the absorption of the dye or the solvent component in the ink tends to be poor.

The pore size distribution of the alumina hydrate is preferably the same as that of the ink receiving layer, and the average pore radius is preferably 20 to 200 ° and the half width of the pore size distribution is preferably 20 to 150 °. Since the pore size distribution of the ink receiving layer depends on the pore size distribution of the alumina hydrate, if it is outside the above range, the pore size distribution of the ink receiving layer cannot be within the above specified range.

The pore volume of the ink receiving layer is 0.4 to 0.6.
A range of cc / g is preferred. When the pore volume of the ink receiving layer is larger than the above range, the ink receiving layer is cracked and powder falls off. When the pore volume is smaller than the above range, the ink absorption tends to be poor. Further, the pore volume of the ink receiving layer is preferably 8 cc / m ² or more. Below this range, particularly when multicolor printing is performed, the ink overflows from the ink receiving layer and bleeding tends to occur in the image. The pore volume of alumina hydrate is 0.4 to 0.4 as in the ink receiving layer.
A range of 0.6 cc / g is preferred. Outside this range, the pore volume of the ink receiving layer cannot be set in the above-mentioned specified range.

In a preferred second aspect of the present invention, the pore size distribution of the ink receiving layer has two or more local maxima. Absorb the solvent component in the ink with relatively large pores,
The dye in the ink is adsorbed by relatively small pores. One of the maxima is preferably a pore radius of 100 ° or less, more preferably 10 to 60 °. Other maxima are pore radius 100-2
A range of 00 ° is preferred. If the former maximum is larger than the above range, the adsorption and fixation of the dye in the ink is reduced, and bleeding and beading are likely to occur in the image. When the latter maximum value is smaller than the above range, the absorption of the solvent component in the ink is reduced, so that it takes time to dry the ink. On the other hand, when the maximum value is larger than the above range, the ink receiving layer tends to crack.

As in the case of the ink receiving layer, the pore diameter distribution of the alumina hydrate is preferably one having a maximum pore radius of 100 ° or less, more preferably 10 to 60 °. The other maximum preferably has a pore radius of 100 to 200 °. Since the pore size distribution of the ink receiving layer depends on the pore size distribution of the alumina hydrate, if it is outside the above range, the pore size distribution of the ink receiving layer cannot be within the above specified range. The total pore volume of the ink receiving layer is 0.1 to 1.0 cc /
The range of g is preferred. More preferably 0.4 to 1.0
cc / g, the most preferred range is 0.4 to 0.6 cc / g.
g. When the pore volume of the ink receiving layer is larger than the above range, the ink receiving layer is easily cracked and powdered. When the pore volume is smaller than the above range, the ink absorption is reduced.

The pore volume of the ink receiving layer was 8 cc /
It is preferably at least m ² . Below this range, the ink may overflow from the ink receiving layer and bleed the image, especially when multicolor printing is performed. Pore radius 100
細孔 The pore volume of pores having a maximum value below 1
The pore volume in the range showing the width of the half-frequency pore radius of the maximum-frequency pore radius of the pore having the maximum value below 00 ° is shown. The pore volume having a maximum value at a pore radius of 100 ° or less is preferably 0.1 to 10% of the total pore volume, and more preferably 1 to 5%. The pore volume of alumina hydrate is 0.1 to 1.0 cc /
g is preferable, and more preferably 0.4 to 1.0 c
c / g. Further, the pore volume of the pore having a maximum value at a pore radius of 100 ° or less is 0.1 to 10 of the total pore volume.
% Is preferable, and more preferably in the range of 1 to 5%.
Since the pore volume of the ink receiving layer depends on the pore volume of the alumina hydrate, it is difficult to keep the pore volume of the ink receiving layer within the above specified range outside the above range.

The alumina hydrate of the first embodiment and the alumina hydrate of the second embodiment may be used as a mixture.

The isothermal nitrogen adsorption / desorption curve can be similarly obtained by the nitrogen adsorption / desorption method. The relative pressure difference (ΔP) between adsorption and desorption at an adsorbed gas amount of 90% of the maximum adsorbed gas amount obtained from the isothermal nitrogen adsorption / desorption curve of the ink receiving layer is 0.
It is preferably 2 or less. A more preferred range is 0.
15 or less, and a more preferred range is 0.10 or less. The relative pressure difference (ΔP) is determined by McBain (J. Am. Che
m. Soc. 57, 699, 1935), it can be used as a measure of the possibility that pores in the form of ink fountains exist. When the relative pressure difference (ΔP) is smaller, the pores are closer to a straight pipe, and when the relative pressure difference (ΔP) is larger, the pore becomes an ink bottle. If it exceeds the above range, it takes time to dry the ink after printing.

The relative pressure difference (ΔP) between adsorption and desorption at an adsorbed gas amount of 90% of the maximum adsorbed gas amount obtained from an isothermal nitrogen adsorption / desorption curve of alumina hydrate is 0.2 or less. Is preferred. A more preferred range is 0.15 or less, and a still more preferred range is 0.10 or less. Outside this range, the isothermal nitrogen adsorption / desorption curve of the ink receiving layer cannot be within the above-mentioned specified range.

The number of hydroxyl groups on the surface of the alumina hydrate can be determined by titration of a triethylaluminum solution. Here, 1 g of the alumina hydrate was weighed and titrated.
The number is preferably at least 10 ²⁰ / g. If the value is less than this value, it is impossible to increase the solid content concentration of the dispersion in which the alumina hydrate is dispersed in water.

The surface potential of alumina hydrate can be generally measured with a zeta potential measuring device. Here, after dispersing alumina hydrate in ion-exchanged water so that the solid content concentration becomes 0.1% by weight, The pH of the dispersion was adjusted to 6 and measured (manufactured by Brookhaven, Bi-ZETA p.
rus). The zeta potential of the dispersion at pH 6 is 15 mV
It is preferable that it is above. If it is less than this value, it is necessary to add an acid to increase dispersibility. The addition of acid causes pungent odor and corrosion.

The viscosity of the dispersion can be measured with a general viscometer. In a dispersion obtained by dispersing the alumina hydrate in ion-exchanged water, nitrate is 0.1% of the alumina hydrate.
It is preferable that the viscosity of the dispersion at a solids concentration of alumina hydrate of 15% by weight and a temperature of 20 ° C. is 75 CPS or less as measured at a shear rate of 7.9 sec ⁻¹ . A more preferred range is 30 CPS or less. If the viscosity exceeds this value, it is necessary to lower the solid content concentration of the dispersion or to add an acid to improve the dispersibility. Here, the above-mentioned nitrate group was obtained by extracting the nitrate group from the alumina hydrate with hot water and measuring it by ion chromatography (Hitachi, L-3720), and was obtained as a percentage by weight in the dry alumina hydrate. The viscosity of the dispersion can be measured by a general viscometer. Here, the viscosity was measured using VISCOMTER manufactured by TOKIMEC.

Particularly preferred combinations of the alumina hydrate having the above-mentioned specific properties and the gelatin obtained by the alkali method are as follows.

A) Alumina hydrate Average particle diameter 35-50 nm BET specific surface area 70-120 m ² / g Average pore radius 60-140 ° Pore volume 0.54-0.58 cc / g pH 4.5-7. 5 (15% dispersion 27
C) Alkali method gelatin Weight average molecular weight 75,000 to 8,000 Number average molecular weight 40,000 to 10,000 Mw / Mn 0.5 to 2.0

B) Alumina hydrate Average particle diameter 20-34 nm BET specific surface area 120-250 m ² / g Average pore radius 20-60 ° Pore volume 0.50-0.55 cc / g pH 2.0-4. 5 (15% dispersion 27
° C) alkali-processed gelatin weight average molecule 45,000 to 8,000, preferably 20,000 to 8
Thousand average molecular weight 30,000-8,000, preferably 20,000-8,000 Mw / Mn 0.5-1.8, preferably 0.6-
1.5

C) Alumina hydrate Average particle diameter 35-50 nm BET specific surface area 70-120 m ² / g Average pore radius 60-140 ° Pore volume 0.54-0.58 cc / g pH 2.0-4. 5 (15% dispersion 27
° C) Alkali method gelatin Weight average molecule 80,000 to 8,000, preferably 20,000 to 8,000 Number average molecular weight 45,000 to 8,000, preferably 20,000 to 8
1000 Mw / Mn 0.5-1.8, preferably 0.6-1.
5

The ink receiving layer is formed by coating a dispersion containing a binder such as alumina hydrate and gelatin on a support using a coating apparatus and drying the dispersion. As the coating method, blade coating method, air knife method,
Roll coat method, brush coat method, gravure coat method, kiss coat method, extrusion method,
A slide hopper (slide bead) method, curtain coat method, spray method, etc. can be used.
In terms of forming a thick ink receiving layer using the sol-gel conversion (setting property) of gelatin, a kiss coat method, an extrusion method, a slide hopper method, and a curtain coat method used as a coating method for a photographic material. Is preferred. In particular, the extrusion method and the slide hopper method are preferable in that thick coating is performed stably with a uniform thickness.

Specifically, for example, in the case of a slide hopper (slide bead) system, US Pat.
As described in No. 791, No. 4001024, No. 5188931 and "Niwa and Gelatin" (published by Japan Niwa and Gelatin Industrial Association, Maruzen, 1987),
The dispersion liquid injected into the slide hopper type liquid injector from the liquid feed pump flows on the slide surface on the layer and rides on the support,
Cold air is blown there, and the dispersion gels into a jelly-like form, enters the drying zone as it is, and is dried to form an ink receiving layer. Thereafter, aging is performed for hardening the gelatin, if necessary. If necessary, the surface smoothness of the ink receiving layer can be improved by using a calender roll or the like.

The coating amount of the dispersion was 0.1% in terms of dry solid content.
The amount is 5 to 60 g / m ² , more preferably 5 to 45 g / m ² , but in order to obtain good ink absorption and resolution,
The thickness of the ink receiving layer needs to be at least μm, preferably at least 20 μm, particularly at least 25 μm.

The dispersion for carrying out the above coating exhibits thixotropy, although the reason is not clear. In the present invention, a TI value is used as an indicator of the degree of thixotropy. TI
The value refers to the Thixotropic Index, using a rotational viscometer such as a B-type viscometer, measuring the viscosity at different rotation speeds, and dividing the value at low speed rotation by the value at high speed rotation. Value, here, 6 rpm / 6
It was calculated as a numerical value of 0 rpm. If this value is greater than 1, the liquid has formed a structure and exhibits thixotropy. In the dispersion of the present invention, the TI value is a solid content concentration,
Although it depends on dispersion conditions, it is preferably from 1.1 to 5.0, more preferably from 1.3 to 4.5, particularly preferably from 1.6 to 4.1. It is preferable to adjust the dispersion to such a range.

Since the dispersion of the present invention exhibits thixotropy,
When a large force is applied, the viscosity will decrease.For example, when coating by a slide hopper (slide bead) method, while flowing out in a layer form from the slide hopper, the viscosity is low, and it is easy to flow. When it gets on the support, it comes to a stopped state (a state where no force is applied), so that the viscosity increases, it becomes difficult to level, and nobody falls. Therefore, dripping of the dispersion liquid is suppressed by this thixotropy simultaneously with the setting property of the alkali method gelatin, and the formation of a thick ink receiving layer becomes easy.

When the TI value is less than the above range, since the thixotropy is low or the thixotropy is not present, dripping of the dispersion applied on the support occurs. Above this range, a dispersing machine that exerts a large force is required to lower the viscosity, and if the apparatus becomes large or the power is insufficient, the viscosity does not decrease and coating becomes difficult.

By using the above-mentioned specific alkaline method gelatin, the dispersion of alumina hydrate / alkali method gelatin is cooled by cold air into a gel state under the influence of the alkaline method gelatin, In addition, the thixotropy of the dispersion also works effectively, preventing dripping while being in a wet state, and making it possible to form a thick ink receiving layer. In addition, because of this thixotropy, the settability of photographic gelatin is usually weak, and the weight-average molecular weight, number-average molecular weight, and jelly strength range are low even for low-molecular-weight gelatin that is not conventionally used alone. If it can be used enough.

The setting of the gelled state was evaluated by measuring the viscosity while lowering the temperature of the dispersion.

In the present invention, the temperature of the dispersion is lowered at a rate of 1 ° C./min from 50 ° C.
Alternatively, the viscosities at 15 ° C., 20 ° C. and 15 ° C. were measured to determine the viscosity ratio between the two. The viscosity ratio between the temperature of 30 ° C and 20 ° C is 1-3
A range of 00 is preferred. The viscosity ratio between the liquid temperature of 30 ° C. and 15 ° C. is preferably in the range of 2 to 1,000. Further, the viscosity ratio between 20 ° C and 15 ° C is preferably in the range of 1.5 to 10,
A range of 9 is more preferred. If the amount is less than the lower limit of the above range, gelation (setting property) becomes insufficient, leveling occurs, and dripping is likely. In addition, the larger the viscosity ratio, the sharper the viscosity sharply increases and the setting property is improved, but if the viscosity is higher than the upper limit of the above range, the viscosity changes significantly with temperature, so that the coating thickness tends to change. Stable coating becomes difficult.

Gelatin has a certain temperature (set temperature)
In the following, it is known that the viscosity increases sharply (setting property), but the mixed dispersion of the alumina hydrate and the alkali method gelatin of the present invention has a smaller increase rate of the viscosity than the dispersion of gelatin alone. . The dispersion of the alumina hydrate and the alkali method gelatin of the present invention has a lower gelatin concentration and the amount of the alumina hydrate is overwhelmingly higher than that of the gelatin dispersion used in conventional silver salts and the like. Many points,
It is presumed that the setting mechanism is different from the point of using low molecular weight gelatin which has not been used conventionally.

The concentration of the solid content of the alkaline gelatin contained in the dispersion is preferably 0.7% to 50%, preferably 0.9% to 40%, and more preferably 1% to 30%. At the usual cooling temperature during coating (4 to 20 ° C.), if the solid content is lower than the above, the gelatinization (setting property) of the alkali method gelatin becomes insufficient, causing leveling and dropping. Further, the thixotropy of the dispersion is low, and it is difficult to form an ink receiving layer having a good thickness. On the other hand, if the solid content is higher than the above, the viscosity of the dispersion becomes too high, making the coating difficult.

The dispersion containing the alumina hydrate and the binder may contain an alumina hydrate dispersant, a thickener,
H adjusters, lubricants, fluidity modifiers, surfactants, defoamers, waterproofing agents, foam inhibitors, release agents, foaming agents, penetrants, coloring dyes, fluorescent brighteners, ultraviolet absorbers, Antioxidants, preservatives, and anti-binders can be added as needed.

The water-resistant agent can be freely selected from known materials such as quaternary ammonium halides and quaternary ammonium salt polymers.

As the support, papers such as appropriately sized paper, non-size paper, resin-coated paper, sheet-like substances such as thermoplastic films, and cloths can be used without any particular limitation.

In the case of a thermoplastic film, polyester,
A transparent film of polystyrene, polyvinyl chloride, polymethyl methacrylate, cellulose acetate, polyethylene, polycarbonate, or the like, or an opaque sheet formed by filling or fine foaming with alumina hydrate can also be used.

When resin-coated paper is used for the support, the same touch, stiffness and texture as those of ordinary photographic prints can be obtained, and the recording medium of the present invention has a high glossiness in the ink receiving layer. In some cases, it is quite similar to a regular photographic print.

In order to improve the adhesion between the support and the ink receiving layer, a surface treatment such as a corona treatment may be performed, or an easy-adhesion layer may be provided as an undercoat layer. Further, in order to prevent curling, a curling preventing layer such as a resin layer or a pigment layer may be provided on the back surface of the support or at a predetermined site.

The ink used in the recording method of the present invention is:
It mainly contains a coloring material (dye or pigment), a water-soluble organic solvent and water. As the dye, for example, a water-soluble dye represented by a direct dye, an acid dye, a basic dye, a reactive dye, an edible dye, or the like is preferable, and in combination with a recording medium, fixability, color development, clarity, and stability. Any material can be used as long as it gives an image that satisfies the required performance, such as light resistance.

The water-soluble dye is generally used by dissolving it in water or a solvent comprising water and an organic solvent. These solvent components are preferably a mixture of water and various water-soluble organic solvents. However, it is preferable to adjust the water content in the ink so as to be in the range of 20 to 95% by weight, preferably 60 to 95% by weight.

Examples of the water-soluble organic solvent include those having 1 to carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol and isobutyl alcohol. 4, alkyl alcohols, amides such as dimethylformamide and dimethylacetamide, ketones or ketone alcohols such as acetone and diacetone alcohol, ethers such as tetrahydrofuran and dioxane, polyalkylene glycols such as polyethylene glycol and polypropylene glycol, and ethylene glycol , Propylene glycol, 1,2,6-hexanetriol,
Alkylene glycols such as thiodiglycol, hexylene glycol, and diethylene glycol in which the alkylene group contains 2 to 6 carbon atoms; glycerin; ethylene glycol methyl ether; diethylene glycol mertyl ether; diethylene glycol ethyl ether; triethylene glycol monomethyl ether; And lower alkyl ethers of polyhydric alcohols such as ethylene glycol monoethyl ether.

Of these many water-soluble organic solvents,
Preferred are polyhydric alcohols such as ethylene glycol and diethylene glycol, and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl ether and triethylene glycol monoethyl ether.
Polyhydric alcohols are particularly preferable because they have a large effect as a lubricant for preventing nozzles from being reduced in clogging due to evaporation of water in the ink and precipitation of a water-soluble dye.

A solubilizing agent may be added to the ink. Typical solubilizing agents are nitrogen-containing heterocyclic ketones, and the intended effect is to dramatically improve the solubility of a water-soluble dye in a solvent. For example, N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone are preferably used. In order to further improve the properties, viscosity modifier, surfactant, surface tension modifier, pH
Additives such as a regulator, a specific resistance regulator, and a storage stabilizer can also be used.

As a method of applying the ink to the recording medium to perform recording, an ink jet recording method is preferable. In the recording method, the ink is effectively removed from the nozzles to apply the ink to the recording medium. Any method may be used as long as it can be obtained. In particular, according to the method described in Japanese Patent Application Laid-Open No. 54-59936, an ink jet method in which ink subjected to the action of thermal energy causes a sudden volume change, and the ink is ejected from a nozzle by the action force due to this state change. Can be used effectively.

The ink receiving layer comprising the alumina hydrate and the alkali-processed gelatin according to the present invention is preferable in that it shows good color reproducibility. Usually, an organic acid or an inorganic acid such as a monocarboxylic acid disclosed in JP-A-4-67985 is usually added to the dispersion of alumina hydrate by several tens% in order to maintain a good dispersion state. The pH of the dispersion may be as high as about 2 to 5, depending on the amount of acid. When such an alumina hydrate dispersion and a normal water-soluble polymer such as a polyvinyl alcohol aqueous solution are mixed as a binder to form an ink receiving layer, and the ink is printed by an inkjet method, the acid changes the ink. This causes a change in color.

However, when the specific alkali method gelatin of the present invention is used as a binder, the change in tint is small even if the acidity of the alumina dispersion is high, the maximum absorption wavelength of the ink is λ1, and printing is performed with the ink. Assuming that the maximum absorption wavelength of the printed portion of the recording medium is λ2, | λ
A printed matter satisfying 1−λ2 | ≦ 30 nm can be obtained. In particular, a change in tint of the magenta ink and the cyan ink can be suppressed, and a printed matter satisfying | λ1−λ2 | ≦ 10 nm can be obtained.

The reason why the color change is reduced by using the alkali method gelatin as described above is not clear. However, the alkali method gelatin probably has a large number of carboxyl groups (H ⁺ releasing) and amino groups ( H ⁺ receptivity), which are considered to have a function of controlling the acidity in the system (ink receiving layer). When ordinary polyvinyl alcohol or the like is used as a binder, the acidity cannot be controlled as described above, so that the color changes.

The ink receiving layer composed of alumina hydrate and a natural polymer such as alkali-processed gelatin or a derivative thereof used in the present invention has a high surface gloss and has no surface scattering, so that a glossy and good image is obtained. , And, as described above, is very similar to a photographic print. The gloss Gs (60) can be measured by the method specified in JIS Z8741 (incident angle: 60 degrees). In the present invention, when a white polyethylene terephthalate film or resin-coated paper is used for the support, It depends on the type and amount ratio of alumina hydrate and alkaline method gelatin, and the method of mixing and dispersing both liquids.
(60) is preferably at least 40, more preferably at least 45, particularly preferably at least 50. In the printing section, G
s2 (60) is preferably 40 or more, more preferably 45 or more, and particularly preferably 50 or more. As described above, it is preferable to adjust the types and ratios of the alumina hydrate and the alkali method gelatin, the method of mixing and dispersing the two solutions, and the like.

Also, in the conventional product, there is a problem that the glossiness of the printed portion is considerably reduced as compared with the glossiness of the non-printed portion. In such a case, since the glossiness of the non-printed part and the printed part are considerably different, when the image is visually observed, a strange impression is given and the image quality is inferior. However, in the present invention, the gloss decrease in the printed area is small and the ratio varies depending on the type and amount ratio of the alumina hydrate and the alkali gelatin, the method of mixing and dispersing the two liquids, and the like.
(60) −Gs2 (60) | ≦ 20, preferably | Gs
1 (60) −Gs2 (60) | ≦ 15, more preferably | Gs1 (60) −Gs2 (60) | ≦ 10.

[0118]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

The physical properties of the gelatin according to this example were measured in the following manner. The results are shown in Table 1 ((a)-
(H)).

1) Molecular weight distribution (weight average molecular weight, number average molecular weight) 2.0 g of gelatin was placed in a 100 ml measuring flask,
An eluent (a 1: 1 mixture of 0.1 M potassium dihydrogen phosphate and 0.1 M disodium hydrogen phosphate) was added and the mixture was sufficiently swollen, and dissolved at about 40 ° C. for about 6 hours. Was diluted 10-fold with an eluent to give a 0.2% test solution.
After filtration through a 45 μm membrane filter, measurement was performed by high performance liquid chromatography. The apparatus and measurement conditions are as follows.

Apparatus (manufactured by Tosoh Corporation) Main unit HLC-8020 System controller SC-8010 Spectrophotometer UV-8010 Autosampler AS-8000 Degasser SD-8000 Printer PP-8010 Condition Column G consisting of vinyl alcohol copolymer
Column for PC (Asahipak GS, manufactured by Asahi Kasei Corporation)
-620, 2 in series) Flow rate 1.0 ml / min Injection volume 100 μl Detection method Optical density in ultraviolet region 230 nm

The calculation of the molecular weight is performed by preparing a calibration curve from the retention time and the molecular weight using albumin, ovalmin, mitochrome or the like whose molecular weight is known in advance under the above conditions, and fitting the retention time of the sample gelatin solution to the calibration curve. The method of calculating the molecular weight was adopted. This method is described in "Relationship Between Molecular Weight Distribution of Gelatin, Viscosity and Jelly Strength" which is a known document at the March Meeting of the Photographic Society of Japan on March 9, 1984.

2) Jelly strength Cooled to 10 ° C. in a specific glass jelly cup

[0124]

[Outside 1] The load for pushing down the surface of the% gelatin by 4 mm with a specific plunger was measured using a jelly tester (manufactured by Stevens).

3) pH A 5% solution of gelatin was measured at a liquid temperature of 35 ° C. using a pH meter (HM-40S, manufactured by Toa Denpa Kogyo KK).

4) Isoionic point cation exchange resin (IR-120 manufactured by Amberlite)
B) 5 ml and anion exchange resin (Amberlite)
IRA-401) 10 ml was mixed and poured into a uniformly packed column (about 40 ° C hot water was passed through the jacket).
After warming through 100 ml of 5 ° C hot water, 100 ml of a 1% gelatin solution is passed at a rate of 50 ml / hour. Then, about 50 ml after removing the first 25 ml flowing out of the column
The solution was taken at a temperature of 35 ° C., and the pH value was measured using a pH meter (HM-40S, manufactured by Toa Denpa Kogyo KK).

5) Zeta potential, particle size 0.1% by weight of a gelatin solution was used as a sample, and a zeta potential measuring device (Bi-ZETA p, manufactured by Brookhaven) was used.
rus) was used to measure the zeta potential. In addition, in the said apparatus, a particle diameter is also measured simultaneously.

6) Swelling ratio It was determined as follows. (A) A hole of about 3 cm in diameter is made in a lid of a 250 cc plastic container, and a nylon mesh of # 400 is covered. (B) Measure the weight (A) of the plastic container together with the mesh. (C) 195 g of a solvent (ion-exchanged water or ethylene glycol solution) is measured in a plastic container. (D) Measure 5 g of gelatin. (E) Put gelatin in a poly container and place in a room temperature atmosphere.
Leave for 4 hours. (F) Open an air hole (approximately 1 cm in width) at the upper end of the plastic container. (G) Tilt the plastic container to discard the solvent, and measure the weight (polycontainer with mesh + swollen gelatin, B). Here, the time for discarding the solvent is determined based on the time for the solvent to flow out. (For example, 30 seconds of ion exchange water,
(H) Ethylene glycol (60 seconds) (h) The swelling ratio is calculated by the following equation.

Swelling rate (%) = {(BA-5) / 5} × 100

The following eight types of alumina hydrates were used in this example.

A to D: US Pat. No. 4,242,271
Aluminum alkoxide was produced by the method described in the above item. Next, the aluminum alkoxide was hydrolyzed by the method described in U.S. Pat. No. 4,202,870, and the mixture was aged under the conditions and equipment shown in Table 2 to obtain a colloidal sol of alumina. This colloidal sol was spray-dried at 75 ° C. to obtain alumina hydrates A to D. The alumina hydrate was amorphous and flat. The physical property values of the alumina hydrate were measured by the methods described above. Table 2 shows the results.

EH: US Pat. No. 4,242,271
Aluminum alkoxide was produced by the method described in the above item. Next, isopropyl titanium (Kishida Chemical Co., Ltd.)
Was mixed with 5/1000 parts by weight of the aluminum alkoxide. The aluminum alkoxide mixture was hydrolyzed by the method described in U.S. Pat. No. 4,202,870, and aged under the conditions and equipment shown in Table 3 to obtain a colloidal sol of alumina containing titanium dioxide. The colloidal sol was spray-dried at 75 ° C. to obtain alumina hydrates E to H. The alumina hydrate was amorphous and flat. The physical property values of the alumina hydrate were measured by the methods described above. Table 3 shows the results.

Examples 1-43 Gelatins (a-h) dissolved and dispersed in ion-exchanged water
A 0 wt% solution and a 15 wt% dispersion of alumina hydrate (A to H) similarly dispersed in ion-exchanged water were mixed at various solid content weight ratios (P / B ratio = solid content of alumina hydrate). Weight / solid weight of gelatin), and a disperser (TK homomixer M, manufactured by Tokushu Kika Kogyo Co., Ltd.)
(Mold) for 30 minutes at 8000 rpm to obtain a mixed dispersion.

This dispersion was applied to a resin-coated paper (manufactured by Oji Paper Co., Ltd., thickness 238 μm, basis weight 249.8 g / m ² ,
All-light whiteness 91.58; RC), or a white polyester film (Lumilar X-21 (trade name, manufactured by Toray Industries, Inc., thickness: 100 μm; WP), or a transparent polyester film (Lumilar T, manufactured by Toray Industries, Inc.) (Product name),
An ink receiving layer having a thickness of 30 μm was formed by applying a slide hopper method on a 100 μm thick TP) to obtain a recording medium. The physical properties of each of the mixed dispersions and the ink receiving layer were measured by the methods described below. Table 4 shows the results.

Evaluation and Measurement Methods of Various Physical Properties of Dispersion 1) Dispersion State The dispersion was visually evaluated.も の: good without gelation or insoluble matter, ○: good but high viscosity, ×: poor gelation or insoluble matter resulting in poor dispersion. 2) TI value B-type viscometer (manufactured by TOKIMEC, VISCOME)
TER), as described above, using the following equation.

TI value = viscosity at 6 rpm / viscosity at 60 rpm Rotor: No. 1. Measurement temperature: 25 ° C. 3) Set temperature, viscosity ratio While lowering the temperature of the dispersion from 50 ° C. at a rate of 1 ° C./min, the above-mentioned B-type rotational viscometer and low viscosity adapter to 10 ° C., No. . The viscosity was measured using a 3 rotor (rotation speed: 3 rpm). The viscosity ratio at a liquid temperature of 30 ° C. and 20 ° C., the viscosity ratio at a liquid temperature of 30 ° C. and 15 ° C., and the viscosity ratio at a liquid temperature of 20 ° C. and 15 ° C. were determined. 4) pH of the dispersion pH of the aqueous dispersion of alumina hydrate and alkaline method gelatin
Is the same pH meter as gelatin (Toa Denpa Kogyo Co., Ltd.)
HM-40S) at a liquid temperature of 25 ° C.

Evaluation and Measurement Methods of Various Properties of Ink Receiving Layer 1) State of coating film of ink receiving layer was visually evaluated. ○:
If defects occur due to rough surface or insoluble matter adhesion,
And 2) pH of the medium JIS P81 using the same pH meter as the dispersion.
The measurement was performed by the method specified in No. 33 (cooling extraction method). 3) Printing characteristics An inkjet printer equipped with 128 nozzles at a nozzle spacing of 16 nozzles per 1 mm and ejecting ink by the action of thermal energy for four colors of Y, M, C, and Bk. Ink-jet recording was performed with the ink having the following composition, and the drying property (absorbency), image density, bleeding, and beading of the ink were evaluated. (A) Ink drying property Y, M, C, Bk of the ink of the following ink composition 1
After solid printing of each ink in single color or multicolor, the drying state of the ink on the surface of the recording medium was examined by touching the recording portion with a finger. The ink amount in monochromatic printing was set to 100%. When the ink amount was 300% and the ink did not adhere to the finger, ◎ was given, when the ink amount was 200% and the ink did not adhere to the finger, and ○ was given when the ink amount was 100% and the ink did not adhere to the finger. (B) Image Density For an ink having the following ink composition 1, the density of an image solid-printed with M ink was measured using a Macbeth reflection densitometer RD-918.
(In each of the four colors,
M had the lowest image density). (C) Bleeding and beading The following ink composition 1 was evaluated for bleeding on the surface of a recording medium after solid printing of each of Y, M, C, and Bk inks in a single color or in multiple colors. In addition, for each of the following two types of ink compositions, beading after solid printing of each of Y, M, C, and Bk inks in a single color or in multiple colors was visually evaluated. The ink amount in monochromatic printing was set to 100%. If the ink amount did not occur at 300%, ◎, if the ink amount did not occur at 200%, ○, the ink amount was 100%
If it did not occur in, it was rated as △.

Ink composition 1 Dye 5 parts Ethylene glycol 10 parts Polyethylene glycol 10 parts Water 75 parts Ink composition 2 Dye 5 parts Glycerin 15 parts Polyethylene glycol 20 parts Water 70 parts Ink dye Y: C.I. I. Direct Yellow 86 M: C.I. I. Acid Red 35 C: C.I. I. Direct Blue 199 Bk: C.I. I. Food Black 2 (d) Glossiness Gloss meter (manufactured by Horiba, Ltd., Gloss Checker IG-)
320) and black (Bk 100%
+ C50% + M50% + Y50%). (E) Amount of change in maximum absorption wavelength (Δλ) The maximum absorption wavelength λ1 of each ink of the above ink composition 1 and the maximum absorption wavelength λ2 of the printing portion of a recording medium printed with each ink are measured with a spectrophotometer ((Co. ) The amount of change in the maximum absorption wavelength of each color (Cyan: △ λC, Magenta: ＭλM), measured using a Hitachi Automated Spectrophotometer U-3410 manufactured by Hitachi, Ltd.
Was determined.

Reference Example 1 10 polyvinyl alcohol (Gohsenol NH-18, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) dissolved in ion-exchanged water
A 15% by weight dispersion of alumina hydrate (C) similarly dispersed in ion-exchanged water was prepared by mixing a 15% by weight solution with a P / B ratio = 10/1.
A recording medium was obtained in the same manner as in Example 1 except that the following conditions were satisfied. Table 4 shows the evaluation results.

When printing was performed on this recording medium using the ink dye of the above-described ink composition 1, it was found that the color had changed visually, and the amount of change in the maximum absorption wavelength was determined. , ΔλC: 41 nm, ΔλM: 22
nm.

Comparative Example 1 A recording medium was prepared by preparing a dispersion liquid in the same manner as in Example 1 except that gelatin was not used. Table 4 shows the evaluation results.

Comparative Example 2 Cast Coated Paper (Kanzaki Paper Co., Ltd., Mirror Coat)
The gloss was measured using a white background (59.9) and black (37.000).
2, the glossiness of the printed portion was reduced by 20 or more, and the image quality deteriorated.

[0143]

[Table 1]

[0144]

[Table 2]

[0145]

[Table 3]

[0146]

[Table 4]

[0147]

[Table 5]

[0148]

[Table 6]

[0149]

【The invention's effect】

1) By using alkali-process gelatin as a binder, utilizing its sol-gel conversion (setting property),
An ink receiving layer having a good thickness can be stably formed with good productivity, and sufficient resolution and good image quality can be obtained.

2) Since alkaline gelatin is used as a binder, even when alumina hydrate having a high acidity is used due to its buffering effect, there is no change in color in the receiving layer, and recording is performed with good color reproducibility. Medium can be obtained.

3) A dispersion obtained by mixing and dispersing a specific alumina hydrate and alkali-processed gelatin has an appropriate thixotropy, and this property effectively works to form an ink receiving layer having a good thickness.

4) A recording medium having an ink receiving layer having high gloss can be obtained. In particular, when resin-coated paper is used as a support, the same gloss, touch, and texture as those of ordinary photographic prints can be obtained. Is obtained. Further, since the gloss of the printed portion is as high as that of the non-printed portion, a high-quality image can be obtained.

5) By incorporating titanium dioxide into alumina hydrate, both the adsorptivity and the dispersibility of the dye could be improved. Even if the solid content concentration of the coating liquid is increased, the viscosity of the dispersion can be lowered, so that the coating thickness of the image receiving layer can be increased. Further, since the printed ink is more easily absorbed and fixed, it is possible to prevent a change with time.

6) Since titanium dioxide is colorless, the ink receiving layer is not colored even if added.

7) When a plate-like alumina hydrate is used, the gap between the particles can be widened when the close-packed structure is adopted, so that a medium having a pore diameter with a certain wide distribution can be obtained.
Since each dye and solvent component is selectively adsorbed on the pores of alumina hydrate having a specific diameter, the use of a medium having a wide pore diameter distribution makes it less likely to be affected by the ink composition. Therefore, the selectivity to the ink composition is increased.

8) When the same pigment or ink receiving layer has two or more maximum pore size distributions, the functional separation of the pores can be performed. Since the dye in the ink can be efficiently absorbed by the pores having a relatively small diameter, a color image having high resolution and sufficient density can be obtained. Since the solvent component in the ink can be rapidly absorbed by the pores having a relatively large diameter, an image with high resolution can be obtained without beading, bleeding, or overflow of the ink.

9) By having no hysteresis, the solvent component in the ink can be easily removed, and the drying property of the ink is improved, and bleeding and show-through can be prevented.

10) Since the dispersibility of alumina hydrate is good, the viscosity of the solution can be lowered even if the solid content concentration of the dispersion is increased.

11) Since the dispersibility is good even when the pH of the alumina hydrate solution is in a neutral range, the amount of the acid added to the dispersion can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a recording medium of the present invention.

[Explanation of symbols]

 Reference Signs List 1 support 2 ink receiving layer

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hitoshi Yoshino 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-3-114873 (JP, A) JP-A-6 −340165 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/00

Claims (25)

(57) [Claims] 1. A BET specific surface area of 70 to 300 m ² / g
A recording medium characterized by having an ink receiving layer containing alumina hydrate as described above and an alkali method gelatin having a weight average molecular weight of 100,000 to 5,000 as measured by a PAGI method. 2. The recording medium according to claim 1, wherein the jelly strength of the gelatin measured by the PAGI method is in the range of 1 to 300. 3. The recording medium according to claim 1, wherein the pH value of the gelatin measured by the PAGI method is 4.5 to 7.0. 4. The recording medium according to claim 1, wherein the gelatin has an isoionic point of 4.1 to 6.0 as measured by a PAGI method. 5. The method according to claim 1, wherein the pH value of the gelatin measured by the PAGI method is in the range of 4.5 to 7.0, and the isoionic point is in the range of 4.1 to 6.0. Recording medium according to the above. 6. The pH value and isoionic point of the gelatin are as follows:
The recording medium according to claim 5, wherein the following relationship is satisfied.
pH value ≥ (isoion point-0.1) 7. The swelling ratio of the gelatin to water is 5
2. The recording medium according to claim 1, which is at least 00%. 8. The recording medium according to claim 1, wherein a swelling ratio of the gelatin to ethylene glycol is 300% or more. 9. The recording medium according to claim 1, wherein the zeta potential of the 0.1% aqueous solution of gelatin is 0 mV or less. 10. The recording medium according to claim 1, wherein the alumina hydrate contains 0.01 to 1.00% by weight of titanium dioxide. 11. The recording medium according to claim 1, wherein the alumina hydrate is a columnar alumina hydrate having an aspect ratio of 3 or less, and forms a bundle oriented in a certain direction. 12. The recording medium according to claim 1, wherein the alumina hydrate is a tabular alumina hydrate having an average aspect ratio of 3 to 10. 13. The recording medium according to claim 1, wherein the alumina hydrate is an amorphous compound. 14. The recording medium according to claim 1, wherein the weight ratio of the solid content of the alumina hydrate and the gelatin is 1: 1 to 30: 1. 15. A BET specific surface area of 70 to 300 m ² /
g of alumina hydrate and an alkali method gelatin having a weight average molecular weight of 100,000 to 5,000 as measured by the PAGI method are dispersed in water, and the TI value is 1.1 to 5.0. Characterized dispersion. 16. The dispersion according to claim 15, wherein a ratio of the viscosity of the dispersion at a temperature of 30 ° C. to a temperature of 20 ° C. is 1 to 300 in a dispersion of alumina hydrate and alkali-processed gelatin in water. liquid. 17. The dispersion according to claim 15, wherein a ratio of the viscosity at a temperature of 30 ° C. to a temperature of 15 ° C. of the dispersion obtained by dispersing alumina hydrate and alkali gelatin in water is 2 to 1000. liquid. 18. The dispersion according to claim 16, wherein the dispersion at a temperature of 20 ° C. and a temperature of 15 ° C. is 1.5 to 10 in a dispersion of alumina hydrate and alkali-processed gelatin in water. A dispersion as described. 19. The gelatin having a solid content of 0.7%.
The dispersion according to claim 15, which is the above. 20. A method according to claim 15, wherein the dispersion is coated on a substrate using a method selected from a kiss coat method, an extrusion method, a slide hopper method and a curtain coat method. Manufacturing method of recording medium. 21. An ink jet recording method in which a small droplet of ink is ejected from a fine hole and applied to a recording medium to perform printing, wherein the recording medium according to claim 1 is used as a recording medium. Characteristic ink jet recording method. 22. The ink jet recording method according to claim 21, wherein heat energy is applied to the ink to form ink droplets. Droplets 23. The ink jet recording method for printing on a recording medium by discharging from the micropores, a recording medium according to claim 1 to 14 as a recording medium
When the medium to be recorded contains alkaline gelatin on the surface, the maximum absorption wavelength of the ink is λ1, and the maximum absorption wavelength of the printing portion of the recording medium printed with the ink is λ2, ≦ 30 nm. An ink jet recording method. 24. The method according to claim 1, wherein ink dots are used.
The printed matter printed on the recording medium according to the above , wherein the surface contains an alkali-processed gelatin, and the gloss Gs1 (60) of the non-printed portion and the gloss Gs2 (60) of the printed portion measured according to JIS Z8741. Are 40 or more, respectively. 25. An ink dot according to claim 1, wherein
A printed matter printed on a recording medium according to the present invention , wherein the surface contains alkali gelatin, and the gloss Gs1 (60) of the non-printed part and the gloss Gs2 (60) of the printed part measured by JIS Z8741. Satisfies the following relationship: | Gs1 (60) −Gs2 (60) | ≦ 20.