JP2714350B2 - Recording medium, method for producing recording medium, inkjet recording method using this recording medium, printed matter, and dispersion of alumina hydrate - 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, a method for producing the recording medium , and a recording medium.
Ink jet recording method using recording medium , printed matter and
The present invention relates to a dispersion of mina hydrate , and particularly to a recording medium having a high image density, a clear color tone, a high resolution, and an excellent ink absorption capacity, a method for producing a recording medium,
Ink jet recording method using this recording medium , printing
And a dispersion of alumina hydrate particularly suitable for producing the recording medium.

[0002]

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 of recording pattern, and no need for development and fixing. It is rapidly spreading in various applications such as information equipment as various image recording devices. I have. 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 they are less expensive than multicolor printing and printing, they are being widely applied to the field of full color image recording. Recording apparatuses and recording methods have been improved with improvements in recording characteristics such as higher recording speed, higher definition, and full colorization. However, advanced characteristics are required for recording media. 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 a screen containing internally added urea-formalin resin powder.
An ink-jet paper in which a water-soluble polymer is impregnated in a sheet is disclosed. 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.

[0004] US Patent Nos. 4,879,166 and 5
104730, JP-A-2-276670, 4
JP-A-37576 and JP-A-5-32037 propose a recording sheet having a layer using alumina hydrate having a boehmite structure.

Further, US Pat. No. 4,374,804
As described in JP-A Nos. 5104730, JP-A-58-110287 and JP-A-4-37576, it is also possible to form a multi-layered ink receiving layer using a silica or alumina material. ing.

However, the conventional recording medium has the following problems.

1) US Pat. No. 5,104,730,
JP-A-2-276670, JP-A-2-276671 and JP-A-3-275378 disclose an average pore diameter of 10%.
A recording medium having a narrow pore diameter distribution of about 30 ° is disclosed. In this pore size distribution, dye adsorption is good, but solvent absorption is insufficient, and beadsing occurs. Here, the beading means that when the next ink dot is applied adjacent to the previous ink dot before the previously applied ink dot is fixed on the recording medium, the ink dot moves in the horizontal direction. This is a phenomenon that irregular movement occurs, and consequently, aggregation occurs between adjacent dots, resulting in uneven image density.

2) Since a large amount of ink is used for printing a color image, the printed ink does not completely absorb in the pores and overflows onto the surface of the ink receiving layer, causing bleeding and deteriorating the quality of printing. Would.

3) High-speed printing requires quick drying. However, since the surface is not dry when printed and discharged from the apparatus due to insufficient absorption speed, the output image may be damaged by contact.

4) US Pat. No. 5,104,730;
JP-A-2-276670, JP-A-2-276671, and JP-A-3-275378 disclose recording media in which the pore diameter distribution is in a very narrow range. However, JP-A-4-267180 and JP-A-5-16517
As disclosed in Japanese Patent Application Laid-Open Publication No. H06-27, each ink dye (cyan, magenta, yellow, and black) and the ink solvent are selectively adsorbed to pores having a specific diameter. Will bleed.

5) Since the viscosity of a dispersion liquid such as a pigment increases with time and coating becomes impossible, there is a problem that the solid content concentration of the liquid cannot be increased. As a countermeasure,
JP-A-4-67986 discloses a method for lowering the degree of polymerization of a binder polymer. However, there are problems such as a decrease in water resistance of the ink receiving layer due to cracking, and no sufficient improvement has been made.

6) There is a problem that the solid content cannot be increased because the viscosity of the dispersion is high. JP-A-4-6798
No. 5 discloses a method of adding an acid such as monocarboxylic acid as a dispersant as a countermeasure. However, manufacturing problems such as generation of pungent odor and corrosion occur.

7) US Pat. Nos. 4,780,356 and 4,780,477 to improve ink absorbency and image resolution.
374804, 504,730, Tokiko 3-72
460, JP-A-55-11829, and 58
-110287, 62-270378,
Japanese Patent Application Laid-Open No. Hei 4-37576 discloses a method in which the ink receiving layer has a two-layer or multilayer structure. But,
In addition to the problem that the coating and drying of the ink receiving layer is performed twice and the number of steps is increased, the physical properties of each layer are different, and there are changes over time, poor appearance such as cracks in the ink receiving layer, and printing. There is also a problem that each layer is separated and peeled off.

8) JP-A-3-281384 discloses that
An alumina hydrate which forms a bundle having a columnar aspect ratio of 3 or less and oriented in a certain direction, and a method of forming an ink receiving layer using the alumina hydrate are disclosed. However, since the alumina hydrate particles are oriented and densely packed, the gap between the alumina hydrate particles in the ink receiving layer tends to be narrow. As a result, the pore diameter is shifted toward the narrow side,
And the pore size distribution tends to be narrow. As a result, there is a problem that beading occurs as described above.

[0015]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made for the purpose of solving the above-mentioned problems, and an object of the present invention is to efficiently absorb a dye and a solvent, which are ink components, to form a color. An object of the present invention is to provide a recording medium which is good and has a high drying speed, and an ink jet recording method using the medium.

Another object of the present invention is to provide a pigment dispersion suitable for producing the recording medium.

[0017]

The above object is achieved by
The following is achieved by the present invention.

[0018] That is, the present invention is placed in the pore radius distribution
A recording medium comprising alumina hydrate having a maximum in the range of 100 ° or less and 100 to 200 ° .

[0019] The present invention, in the recording medium provided on a substrate an ink-receiving layer containing a pigment and a binder, wherein the alumina hydrate as a pigment, and Oite ink-receiving layer in the pore radius distribution, Less than 100Å and 100-200Å
A recording medium having a maximum in a range .

[0020] The present invention is a fibrous material, characterized in that internally added fraud and mitigating risk alumina hydrate having a <br/> maximum in the range of 100Å or less and 100~200Å the pore radius distribution It is a recording medium.

Furthermore the present invention, Oite the nitrate to contain and and the pore radius distribution from 0.1 to 1.0 wt%, and 100Å or less
When the alumina hydrate having a maximum in the range of 100 to 200 ° was dispersed in ion-exchanged water at a solid content of 15% by weight, the viscosity was measured at 20 ° C. and a shear rate of 7.9 sec ⁻¹ , and the viscosity was 75 C.
It is PS hereinafter Oite the nitrate to contain and and the pore radius distribution from 0.1 to 1.0 wt%, 100 Å or less and 100
When the alumina hydrate having a maximum in the range of ~ 200 ° is dispersed in ion-exchanged water at a solid concentration of 20% by weight, the viscosity is measured at 20 ° C and a shear rate of 10.2 sec- ¹ to 100C.
PS or less, or 0.1-1.0
Wt% content to and Oite the pore radius distribution, 100 Å or less
Of alumina hydrate having a maximum in the range of 100 to 200 ° in ion-exchanged water at a solid content concentration of 25% by weight was measured at 20 ° C. and a shear rate of 10.2 sec- ¹ to 5
It is a dispersion of alumina hydrate characterized by being not more than 00 CPS.

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

By using the recording medium of the present invention, the dye and the solvent, which are the components of the ink, are efficiently absorbed, whereby there is an advantage that printing with good coloring and quick drying can be realized. .

The recording medium of the present invention is a recording medium containing, as an essential component, at least an alumina hydrate having the above-described characteristics in the pore radius distribution. Or an ink receiving layer formed mainly of the above-mentioned alumina hydrate and a binder on a base material as a single layer, as shown in FIG. Configuration. Alumina hydrate has a positive charge, so the ink dye can be fixed well and an image with good color development can be obtained. Also, browning and lightfastness of black ink, which were conventionally generated by using a silica compound, are Because there is no problem of the above, it is the most preferable material for the ink receiving layer.

The alumina hydrate used in the recording medium of the present invention is preferably an amorphous alumina hydrate as analyzed by X-ray diffraction.

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 of 0, 1, 2 and 3, and m represents 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.

Alumina hydrate can be produced by a known method such as hydrolysis of aluminum alkoxide and hydrolysis of sodium aluminate. Rosek et al. (C
allCzech Chem Commun, 5
6, 1253-1262, 1991) report that the porous structure of alumina hydrate is affected by deposition temperature, solution pH, aging time, and surfactant.

For example, Kodansha, Catalyst Course, Vol. 5, Engineering, Catalyst Design (1985), page 123, describes that alumina hydrate generally has one maximum pore size distribution. I have. Kobayashi (Surface, Volume 15, 282,
1977) alumina hydrate has a maximum pore size distribution of 1
One that reports. Rosek et al. (Coll.
ect Czech. Chem. Commun. 5
6 (6), 1263-1269, 1991)
It has been reported that at relatively low temperatures of 低 い 50 ° C., aluminum hydroxide precipitated at pH 7-8 exhibits a bimodal pore structure with maxima in the large and medium pore regions.

The shape of the alumina hydrate used in the present invention is as follows.
Preferably, the plate-like shape has an average aspect ratio of 3 to 10, and the aspect ratio of the plate surface is 0.6 to 1.0. The definition of the aspect ratio can be obtained by the method described in Japanese Patent Publication No. Hei 5-16015. 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. When the average aspect ratio is smaller than the above range, the pore size distribution range of the ink receiving layer becomes narrow, and when the average aspect ratio is large, it becomes difficult to produce alumina hydrate with a uniform particle size. When the average aspect ratio is smaller than the above range, the pore size distribution becomes narrow similarly. Among the alumina hydrates, pseudo-boehmite is described in the literature (Rosek J., et al.
Applied Catalysis, Vol. 74, 29-
36, 1991), it is generally known that there are cilia-like and other shapes.

According to the knowledge of the present inventor, even in the case of alumina hydrate, the plate-like shape has better dispersibility than the hairy bundle (ciliform), and when the ink receiving layer is formed, the drawing in FIG. As shown in the substitute photograph, since the orientation of the alumina hydrate particles becomes random, the pore size distribution becomes wider, which is more preferable.

It should be noted that page 402 of the Paper Processing Handbook states that the aluminum hydroxide particles are in the form of hexagonal flat plates. In addition, Heidilight (trade name, manufactured by Showa Denko),
Aluminum hydroxide such as HYDRAL (trade name, manufactured by ALCOA) is known. Further, JP-A-2-27667
No. 0 discloses a hairy bundle alumina sol having an aspect ratio of 2 to 10, and JP-A-3-285814 discloses a plate-like boehmite sol having an aspect ratio of 2 to 10. However, each of the above documents does not show any relationship between the shape of the alumina hydrate and the pore structure or dispersibility in the particles as described below.

The BET surface area of the alumina hydrate, the pore size distribution of the alumina hydrate and the ink receiving layer containing the alumina hydrate, the pore volume as described below, and the isothermal adsorption / desorption curve are as follows. It can be determined simultaneously by the desorption method. The BET specific surface area of the alumina hydrate used in the present invention is preferably in the range of 70 to 300 m ² / g. BE
When the T specific surface area is smaller than the lower limit of the above range, the pore size distribution is shifted to the larger side and the dye in the ink cannot be sufficiently adsorbed and fixed. There is a possibility that the coating cannot be performed and the pore size distribution cannot be controlled.

The method for producing the alumina hydrate used in the present invention is not particularly limited, but is preferably a method capable of producing an amorphous alumina hydrate, for example, a Bayer method, alum pyrolysis. Any method such as a method can be adopted.

In the present invention, a particularly preferable method for producing an amorphous alumina hydrate is a method of obtaining an alumina hydrate by adding an acid to a long-chain aluminum alkoxide and hydrolyzing it. No.
Here, the long-chain aluminum alkoxide is, for example, an alkoxide having 5 or more carbon atoms, and further has 12 to 12 carbon atoms.
Use of the alkoxide of No. 22 is preferable because it facilitates removal of an alcohol component and control of the shape of alumina hydrate as described later. The above method has an advantage that impurities such as various ions are less likely to be mixed as compared with a method for producing alumina hydrogel or cationic alumina. Furthermore, long-chain aluminum alkoxides have an advantage that the alcohol hydrate of alumina hydrate can be completely removed as compared with the case where short-chain alkoxides such as aluminum isopropoxide are used, because alcohol after hydrolysis is easily removed. is there. Further, in the method using the long-chain aluminum alkoxide, the shape of the alumina hydrate particles obtained by the hydrolysis is easily formed into a plate shape, and the particle shape is easily controlled. In this method, it is preferable to set the pH of the solution at the start of hydrolysis to 6 or less in order to obtain amorphous alumina hydrate. Here, when the pH becomes 8 or more,
The finally obtained alumina hydrate becomes crystalline.

The alumina hydrate obtained by the above method undergoes a hydrothermal synthesis step to grow particles (ripening step). By adjusting the conditions of the step, the pore shape of the alumina hydrate particles can be controlled to a specific range. When the aging time is appropriately set, primary particles of alumina hydrate having a relatively uniform particle diameter grow, and the gaps between the primary particles forming the pores are uniform and the pore diameter distribution becomes narrow.
If the aging time is made longer than this condition, an alumina hydrate having a bimodal pore size distribution can be obtained. The sol obtained here can be used as it is as a dispersion liquid as disclosed in JP-A-2-276670, but in the present invention, the sol is dried once by a method such as spray drying to obtain a powder. After being in a state, it is preferable to form a dispersion. In this case, the dispersibility of the alumina hydrate in water is further improved.

The alumina hydrate obtained by this method has two or more maxima in the pore radius distribution. The pore structure is formed mainly by gaps between primary particles of alumina hydrate. The reason for having two or more maxima is that the alumina hydrate used in the present invention is in the form of a flat plate, and in the dry powder, each primary particle is oriented in a random direction. This is considered to be caused by the occurrence of the gap between the portions overlapping in the direction and the gap between the end surface and the portion overlapping the main plane or the end surface. Thus, two or more maxima of the pore radius distribution are all generated by the gap between the primary particles, and at least one of the pore diameters having the maximum is the minor axis or major axis diameter of the primary plane of the primary particles. Similarly, at least one of the pore diameters having other maxima is similarly several times the minor axis or major axis diameter of the main plane. As described above, the alumina hydrate of the present invention has two or more maxima in the pore radius distribution. Such an alumina hydrate is dispersed up to the primary particles in the coating dispersion, but the pore radius distribution having two or more maxima indicates the dispersion of the alumina hydrate and the coating on the substrate. This is maintained even if the ink receiving layer is formed through a drying step. The reason for this is that, as shown in the drawing substitute photograph of FIG.
The primary particles are oriented in random directions, and, like in the case of alumina hydrate, the gap between the primary particles overlapping in the main plane direction of the flat plate via the binder, the end face and the main plane or end face are different. It is presumed that two or more local maxima of the pore radius distribution resulting from the occurrence of the gaps between the overlapping portions via the binder are also maintained in the ink receiving layer.

JP-A-58-110287 discloses a recording sheet having a pore diameter peak at 0.05 μm or less and 0.2 to 10 μm. However, the former peak depends on the gap between the primary particles, while the latter peak is
The present invention differs from the present invention in that primary particles are formed by gaps between aggregated secondary or tertiary or higher particles, and two or more maxima each arise from the gaps between primary particles. Therefore,
The peak positions of the pore diameters are completely different.

In one embodiment of the recording medium of the present invention described above, a coating liquid (dispersion of alumina hydrate) in which the above-mentioned alumina hydrate as a pigment and a binder are blended on a substrate.
To form an ink receiving layer. The physical properties of the ink receiving layer are not determined only by the alumina hydrate used,
Binder type and mixing amount, coating liquid concentration, viscosity, dispersion state, coating device, coating head, coating amount, dry air flow,
Since it varies depending on various manufacturing conditions such as temperature and blowing direction, it is necessary to control the manufacturing conditions within an optimum range in order to obtain the characteristics of the ink receiving layer according to the present invention.

Further, in the recording medium of the present invention, the pore radius distribution of the ink receiving layer also has two or more maxima. The relatively large pores absorb the solvent component in the ink, and the relatively small pores adsorb the dye in the ink. One of the maxima is preferably a pore radius of 100 ° or less, more preferably 10 to 60 °. The other maximum preferably has a pore radius of 100 to 200 °. If the former maximum is larger than the upper limit of the above range, the adsorption and fixation of the dye in the ink is deteriorated, and the image bleeds, and beading occurs.
If the maximum of the latter is smaller than the lower limit of the above range, the absorption of the solvent component in the ink will be poor, the drying of the ink will be poor and the ink receiving layer surface will not dry when printed and carried out of the apparatus, and the latter maximum will be obtained. Is larger than the upper limit of the above range, cracks are likely to occur in the ink receiving layer.

In the present invention, the pore radius distribution of the alumina hydrate also has two or more maxima. As for the pore size distribution, one of the relatively small maxima is preferably a pore radius of 100 ° or less, more preferably 10 °, as in the ink receiving layer.
~ 60 °. A relatively large maximum has a pore radius of 100 to
A range of 200 ° is preferred. As described above, the pore structure of the ink receiving layer is formed by primary particles of alumina hydrate, but this pore structure has already formed its properties in alumina hydrate. When the maximum of the distribution is out of the above range, the pore radius distribution of the ink receiving layer cannot be in the above specified range.

The total pore volume of the ink receiving layer is 0.1 to
A range of 1.0 cc / g is preferred. A more preferred range is 0.4 to 0.6 cc / g. If the pore volume of the ink receiving layer is larger than the above range, the ink receiving layer will be cracked and fall off. If it is smaller than the above range, ink absorption will be poor. Further, the pore volume of the ink receiving layer is preferably 8 cc / m ² or more. Below the above range, especially when multicolor printing is performed, ink overflows from the ink receiving layer and bleeding occurs in the image. Pore radius 100
The pore volume of pores having a maximum value below Å is preferably 0.1 to 10% of the total pore volume, more preferably 1 to 5%.

Here, the pore volume of pores having a pore radius of 100 ° or less is defined as pores in a range up to the pore radius showing half the frequency of the pore radius showing the maximum value in the pore radius distribution. The width of the volume. If the pore volume of the pore having a maximum value at a pore radius of 100 ° or less of the ink receiving layer is smaller than the above range, the adsorption of the dye in the ink becomes worse. Gets worse. The total pore volume of the alumina hydrate is also 0.4 to 1.0 cc / g, and more preferably 0.4 to 0.6 cc / g. The volume of pores having a maximum value at a pore radius of 100 ° or less is preferably 0.1 to 10% of the total pore volume. A more preferred range is 1 to 5%. Since the pore volume of the ink-receiving layer depends on the pore volume of the alumina hydrate, the pore volume of the ink-receiving layer cannot be set to the above specified range outside the above range.

In the recording medium having an ink receiving layer on the base material of the present invention, 90% of the maximum amount of adsorbed gas is adsorbed as determined from the isothermal nitrogen adsorption / desorption curve of the ink receiving layer derived by the nitrogen adsorption / desorption method. Relative pressure difference between adsorption and desorption (Δ
P) is preferably 0.2 or less. A more preferred range is 0.15 or less, and a still more preferred range is 0.10.
It is as follows. The relative pressure difference (ΔP) is McBain
(J. Am. Chem. Soc., 57, 699, 1
935) can be used as a measure of the possibility of the presence of pores in the shape of an inkwell. 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 pores are shaped like an ink bottle. When the relative pressure difference (ΔP) is out of the above range, the drying property of the ink after printing deteriorates. still,
Japanese Patent Application Laid-Open No. 60-245588 discloses that the pore shape of alumina xerogel used for the ink receiving layer is preferably uniform and straight with a small degree of labyrinth, an ink bottle shape with a narrow entrance, and a constricted part in the middle. It is described that a gourd shape, a meandering shape, etc. are not preferable from the viewpoint of the absorption rate, but no specific method for measuring actual physical property values or the like is described.

The recording medium of the present invention having an ink receiving layer containing the alumina hydrate was determined from an isothermal nitrogen adsorption / desorption curve of the alumina hydrate derived by a nitrogen adsorption / desorption method. , The maximum adsorbed gas amount of 90
% Relative pressure difference (ΔP) between adsorption and desorption with the adsorption gas amount of
It is preferably 0.2 or less. A more preferred range is 0.15 or less, and a still more preferred range is 0.10 or less. Outside this range, the relative pressure difference (ΔP) obtained from the isothermal nitrogen adsorption / desorption curve of the ink receiving layer cannot be in the above-mentioned specified range.

The number of hydroxyl groups on the surface of the alumina hydrate used for the recording medium of the present invention 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 number of hydroxyl groups of such alumina hydrate can be determined by titration of a triethylaluminum solution.

The surface potential of the alumina hydrate can be determined with a zeta potentiometer. JP-A-60-2329
Japanese Patent Publication No. 90 discloses that the alumina compound has a positive charge, and furthermore, the values of the zeta potential in Examples, but do not disclose specific measuring methods and conditions. The value of the zeta potential is determined by measuring cell, electrode structure, applied voltage, solid concentration, dispersion pH,
Since it depends on the dispersing agent and additives used, the absolute value cannot be directly compared unless measurement conditions and equipment are unified.

The alumina hydrate used in the present invention may have a zeta potential of 15 mV or more at a pH of 6 in a 0.1% by weight aqueous dispersion without adding a dispersant and additives. preferable. When the zeta potential is within this range, the alumina hydrate can easily disperse in the dispersion to the level of primary particles. When the zeta potential is less than 15 mV, agglomerates and precipitates are generated as the solid content concentration increases, and when the binder dispersion and the alumina hydrate are mixed, the particles partially aggregate to form a large lump. To form For this reason, particularly in a recording medium having an ink receiving layer, the pore size of the ink receiving layer becomes extremely large, the strength of the ink receiving layer is reduced, powder is dropped, and the fixability of the dye at the time of printing is reduced. There is a risk of going bad.

Since alumina hydrate is generally stable in a low pH range, it is known that an acid is added to lower the pH of a dispersion liquid in order to improve dispersibility.
The addition of an acid is not preferable in that a pungent odor or corrosion is generated and the kind of a binder to be used is restricted. Also,
A known method of adding a dispersant is not preferable because repelling or the like of the liquid occurs when the dispersion is applied. On the other hand, when the pH region becomes higher, depending on the type of the alumina hydrate, the primary particles aggregate and the particle size becomes larger, which may have an apparently high zeta potential. The zeta potential of the alumina hydrate defined in the present invention is, of course, measured in a state where such particles do not agglomerate. It is effective to measure the particle size of. As a method for measuring the particle diameter, a known method can be adopted. However, it is necessary to confirm that the particle size in the dispersion at pH 6 at which the zeta potential is measured has substantially the same value as the particle size in the dispersion at pH 4 at which the particles are stably dispersed. .

In the present invention, preferably, the specific alumina hydrate as described above, wherein the nitrate is 0.1 to 1.0.
% By weight of a dispersion obtained by dispersing a solid content concentration of 15% by weight in ion-exchanged water at a dispersion temperature of 20 ° C.
When measured at a shear rate of 7.9 sec ⁻¹ , it is 75 CPS or less,
Especially preferably, it is 30 CPS or less. Preferably, the viscosity of a dispersion obtained by dispersing the same alumina hydrate containing 0.1 to 1.0% by weight of nitrate in ion-exchanged water at a solid concentration of 20% by weight is preferably the dispersion temperature. Measured at 20 ° C. and a shear rate of 10.2 sec ⁻¹ , and is 100 CPS or less,
Particularly preferred is 80 CPS or less. Furthermore, the viscosity of a dispersion obtained by dispersing the same alumina hydrate containing 0.1 to 1.0% by weight of nitrate in ion-exchanged water at a solid content concentration of 25% by weight has a dispersion temperature of 20 ° C. 10. shear rate
It is preferably 500 CPS or less, and more preferably 460 CPS or less, measured at 2 sec ^-1 . In each case described above, if the viscosity exceeds the upper limit of the range, it is necessary to reduce the solid content concentration of the dispersion, which is not preferable in terms of mass productivity.

The viscosity of the alumina hydrate dispersion can be measured using, for example, a rotational viscometer such as a B-type viscometer.

The aforementioned US Pat. No. 4,879,166.
No. 5,104,730, JP-A-2-276670
Report, JP-A-4-37576, JP-A-5-32037
Comparison between the conventional example using pseudo-boehmite described in the above and the present invention
As a result of the examination, the difference is as follows.

1) In the above-mentioned conventional example, the pore diameter distribution is within a range of ± 10 ° of the average pore radius, and is 45% of the total pore volume.
Alternatively, only the range in which the pore volume is 55% and the width of the pore size distribution is narrow is disclosed. In contrast, the present inventors have found that an alumina hydrate having two maximums in the pore size distribution and an ink receiving layer using the alumina hydrate are effective. By having these two maxima, the functional separation of the pores is performed, the solvent components in the ink are absorbed by the relatively large pores, and the dye components in the ink are absorbed by the relatively small pores. By doing so, it has been found that even if printing is performed at high speed in multiple colors, the ink is dried quickly and a recording medium with good coloring can be obtained.

2) In the above-mentioned conventional example, regarding the pore diameter and the pore volume, the total pore volume at a pore radius of 10 to 40 ° is 0.2 to 1.0 cc / g, and the total pore volume at 40 to 100 ° is 0.1 to 0.1 cc / g. 1
~ 0.4cc / g, 0.1cc at 100 ~ 1000kg
/ G. On the other hand, the present inventor has set that the relationship between the pore volume per unit area of the ink receiving layer and the isothermal nitrogen adsorption / desorption curve is within the range described in this specification, so that ink adsorption and drying after printing are performed. Was found to be significantly improved.

3) The above-mentioned conventional example describes a pseudo-boehmite sol and a method for producing an ink receiving layer using the same. It also describes the shape of pseudo-boehmite and the solid content of the dispersion. On the other hand, the present inventor has found that tabular alumina hydrate is used. Since such a plate-like amorphous alumina hydrate can be preferably produced by hydrolyzing a long-chain aluminum alkoxide, it is possible to easily obtain an alumina hydrate having a small amount of ions or raw material alcohol mixed therein. Can be. In this step, the alumina hydrate easily becomes tabular grains and the shape can be easily controlled. Dispersibility is extremely high as compared with conventionally known hairy bundles of alumina hydrate. Further, by using alumina hydrate once dried and powdered without preparing a dispersion (particularly a coating dispersion) directly from the sol, a dispersion having a high solid content and a low viscosity can be easily obtained. Can be obtained.

In the recording medium of the present invention, a binder that can be used in combination with alumina hydrate can be freely selected from water-soluble polymers. For example, polyvinyl alcohol or a modified product thereof (cation modified, anionic modified, silanol modified),
Cellulose such as starch or a modified product thereof (oxidized or etherified), gelatin or a modified product thereof, casein or a modified product thereof, carboxymethylcellulose, gum arabic, hydroxyethylcellulose, hydroxypropylmethylcellulose, etc. -Derivatives, SBR latex, NBR latex, conjugated diene-based copolymer latex such as methyl methacrylate-butadiene copolymer, functional group-modified polymer latex, and vinyl-based copolymer such as ethylene-vinyl acetate copolymer Latex, polyvinylpyrrolidone, maleic anhydride or its copolymer, acrylate copolymer, etc. are preferred. These binders can be used alone or in combination of two or more. The mixing ratio of the alumina hydrate and the binder can be arbitrarily selected from 1: 1 to 30: 1. A more preferred range is 5: 1 to 2
5: 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 occur. When the amount is more than the above range, the pore volume is reduced and ink absorption is reduced. Deteriorate.

The alumina hydrate and the binder may contain a dispersant, a thickener, a pH adjuster, a lubricant, a fluidity modifier, a surfactant, an antifoaming agent, a waterproofing agent, and a foam inhibitor, if necessary. ,Release agent,
A foaming agent, a penetrating agent, a coloring dye, a fluorescent whitening agent, an ultraviolet absorber, an antioxidant, a preservative, and an antibacterial agent can be added as necessary.

The water-proofing agent can be freely selected from known materials such as halogenated quaternary ammonium salts and quaternary ammonium salt polymers.

As the base material of the recording medium of the present invention, suitable sized paper, non-sized paper, papers such as resin-coated paper using polyethylene and the like, and sheets such as thermoplastic films. Materials and fabrics can be used. In the case of a thermoplastic film, polyester, polystyrene, polyvinyl chloride, polymethyl methacrylate, cellulose acetate,
It is also possible to use a transparent film such as polyethylene or polycarbonate, or an opaque sheet by filling with a pigment or fine foaming.

The dispersion of alumina hydrate suitably used for producing the recording medium of the present invention can be prepared as follows. The powdery alumina hydrate is added to ion-exchanged water to prepare a liquid having a predetermined solid content concentration. Subsequently, a mechanical shearing force or ultrasonic waves are applied to the dispersion as needed to control the particle size of the alumina hydrate. Thereafter, a separately prepared binder dispersion is added, and if necessary, a treatment such as dispersion, heating, and defoaming is performed to obtain a final dispersion for coating.

In the recording medium having an ink receiving layer of the present invention, a method for forming an ink receiving layer on a substrate is as follows. A method of coating and drying on top can be used. Coating methods include commonly used blade coaters, air knife coaters, roll coaters, brush coaters, carten coaters, bar coaters, and gravure. A coating technique using a coater, a spray device, or the like can be employed. The coating amount of the dispersion is 0.5 to 60 g / m ² , more preferably 5 to 45 g / m ^{2 in} terms of dry solid content.
m ² . If necessary, the surface smoothness of the ink receiving layer can be improved by using a calendar roll or the like after coating.

The recording medium of the type to which the alumina hydrate of the present invention is internally added is an alumina hydrate (a dispersion thereof).
Can be produced by using an internal addition method in which a is added to a slurry containing a fibrous substance in a papermaking process. In such a method,
If necessary, a paper strength improver, a retention improver, and a colorant can be added and used. As a yield improver,
It can be selected or used in combination with cationic retention enhancers such as cationized starch and dicyandiamide formalin condensate, and anionic retention enhancers such as anionic polyacrylamide and anionic colloidal silica.

The ink used for recording on the recording medium of the present invention mainly contains a coloring material (dye or pigment), a water-soluble organic solvent and water. As the dye, for example, a direct dye, an acid dye, a basic dye, a reactive dye, a water-soluble dye represented by an edible dye, and the like, are preferable, and in combination with the above-described recording medium, fixability, color forming property, sharpness, Any material can be used as long as it provides an image satisfying the required performance such as stability, light fastness and the like.

The water-soluble dye is generally used by dissolving it in water or a solvent comprising water and an organic solvent. The solvent component is preferably a mixture of water and various water-soluble organic solvents. Is used, and it is preferable to adjust the water content in the ink so as to be in the range of 20 to 90% by weight, preferably 60 to 90% by weight.

Examples of the water-soluble organic solvent include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, and n-butyl alcohol.
Alkyl alcohols having 1 to 4 carbon atoms, such as alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, amides such as dimethylformamide, dimethylacetamide, acetone, diacetone alcohol Ketones or ketone alcohols; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol; propylene glycol; , 6-hexanetrio-
Alkylene glycols having an alkylene group containing 2 to 6 carbon atoms, such as glycerol, thiodiglycol, hexylene glycol, and diethylene glycol; Lower alkyl ethers of polyvalent alcohols such as diethylene glycol ethyl ether, triethylene glycol monomethyl ether and triethylene glycol monoethyl ether are exemplified.

Among these many water-soluble organic solvents,
Polyalkyl alcohols such as diethylene glycol, and lower alkyl ethers such as triethylene glycol monomethyl ether and triethylene glycol monoethyl ether are preferred. Polyvalent alcohols are
It is particularly preferable because it has a great effect as a lubricant for preventing a decrease in nozzle clogging due to evaporation of water in the ink and precipitation of a water-soluble dye.

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

As a method for 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 and the ink is applied 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, the ink subjected to the action of thermal energy causes a rapid change in volume, and the ink is ejected from the nozzles by the action force due to this state change. Can be used effectively.

[0069]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. Various properties according to the present invention were measured in the following manner. 1) BET specific surface area, pore diameter distribution, pore volume, and isothermal desorption curve characteristics The recording medium having an ink receiving layer formed on an alumina hydrate or PET film is sufficiently heated and degassed before nitrogen adsorption and desorption. It measured using the separation method. (Cantachrome Co., Ltd.
Autosorb 1) The method of Brunauer et al. Was used to calculate the BET specific surface area. (J. Am. Chem. Soc., 60, 3
09, 1938)-Calculation of pore radius and pore volume used the method of Barrett et al. (J. Am. Chem. Soc., Vol. 73,
373, 1951) ・ From the isothermal nitrogen adsorption / desorption curve, 90% of the maximum adsorbed gas amount
The relative pressure difference (ΔP) between adsorption and desorption with the amount of adsorbed gas was determined. 2) X-ray diffraction image This was performed using an X-ray diffractometer (manufactured by Rigaku Corporation). 3) Observation of shape of alumina hydrate (aspect ratio, aspect ratio, particle shape) A sample for measurement was prepared by dispersing alumina hydrate in ion-exchanged water and dropping it on a collodion film. This sample was observed with a transmission electron microscope (H-500, manufactured by Hitachi, Ltd.). 4) Number of hydroxyl groups 1 g of alumina hydrate was weighed out and titrated with triethylaluminum. 5) Zeta potential Alumina hydrate was dispersed in ion-exchanged water so that the solid content concentration was 0.1% by weight, and the pH of the dispersion was adjusted to 6 with nitric acid, and measured. . (Bi-ZETA plus, manufactured by Brookhaven, liquid temperature 20 ° C., using an acrylic cell) 6) Solution viscosity An aqueous dispersion having a solid content concentration of alumina hydrate of 15% by weight was prepared. VI manufactured by TOKIMEC
The measurement was performed at a shear rate of 7.9 sec ^-1 using a SCOMTER. Further, an aqueous dispersion having a solid content concentration of alumina hydrate of 20 and 25% by weight was prepared, and TOK was prepared at a temperature of 20 ° C.
The measurement was performed at a shear rate of 10.2 sec ^-1 using VISCOMTER manufactured by IMEC. 7) Nitrate The nitrate was extracted from alumina hydrate with hot water, measured by ion chromatography (Hitachi, L-3720), and expressed as% by weight in the alumina hydrate. 8) Printing characteristics Using an ink jet printer provided with four nozzles of Y, M, C, and Bk with an ink jet head having 128 nozzles at a nozzle interval of 16 nozzles per 1 mm, using an ink having the following composition, Ink jet recording was performed to evaluate the drying property (absorbency), image density, bleeding, and beading of the ink.

(1) Ink Drying Property After solid printing of each of Y, M, C, and Bk inks in a single color or in multiple colors, the drying state of the ink on the surface of the recording medium was examined by touching the recording portion with a finger. Ink amount for single color printing is 1
00%. When the ink amount is 300%, the ink does not adhere to the finger, ◎: when the ink amount is 200%, the ink does not adhere to the finger, ○. When the ink amount is 100%, the ink does not adhere to the finger, Δ, and when the ink amount is 100%, the ink is 100%. Is attached to the finger ×
And (2) Image Density The image density of an image solid printed with Bk ink was evaluated using a Macbeth reflection densitometer RD-918. (3) Bleeding and Beading Bleeding and beading 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 were visually evaluated. The ink amount in monochromatic printing was set to 100%. If the ink was not generated at the ink amount of 300%, ◎, if the ink was not generated at the ink amount of 200%, 、, the ink amount was 100
% If it does not occur, and × if it occurs at 100%
And

Ink composition Dye 5 parts Diethylene glycol 10 parts Polyethylene glycol 10 parts Water 75 parts Dye Y: C.I. I. Direct Yellow-86 M: C.I. I. Acid Red 35 C: C.I. I. Direct Bull-199 Bk: C.I. I. Food Black 2

Examples 1 to 4 Aluminum dodecoxide was prepared by the method described in US Pat. No. 4,242,271. Next, the aluminum alkoxide was hydrolyzed by the method described in U.S. Pat. No. 4,202,870 to produce an alumina slurry. Water was added to this alumina slurry until the alumina hydrate solid content became 7.9%. Alumina slurry
Had a pH of 9.5. The pH was adjusted by adding a 3.9% nitric acid solution. A colloidal sol was obtained under each aging condition shown in Table 1. This colloidal sol was spray-dried at 75 ° C. to obtain an alumina hydrate. This alumina hydrate was amorphous as shown in the X-ray diffraction image of FIG. Also, a drawing substitute photograph of FIG. 3 (electron microscope photograph: 30,000 times magnification)
As shown in FIG. The physical properties of the alumina hydrate were measured by the above methods. The results are shown in Table 2 and FIG.
And FIG.

Polyvinyl alcohol (gosenol NH18, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was dissolved and dispersed in ion-exchanged water to obtain a 10% by weight solution. Examples 1-4
Was similarly dispersed in ion-exchanged water to obtain a 15% by weight dispersion. The alumina hydrate and the polyvinyl alcohol solution were weighed in such a manner that the solid content of the polyvinyl alcohol and the solid content of the alumina hydrate became 1:10 by weight, and mixed, stirred and mixed. A dispersion was obtained. A 100 μm thick PET
The film was die-coated on a film (Lumilar, manufactured by Toray Industries, Inc.) to obtain a receiving layer having a thickness of 30 μm. The drawing substitute photograph (electron micrograph: magnification of 50,000 times) of FIG. 4 is obtained by observing a cross section of the ink receiving layer, and tabular alumina hydrate is randomly arranged in the ink receiving layer. The physical properties of the ink receiving layer were measured by the above methods. Table 3 shows the measurement results.

Examples 5 to 8 The alumina hydrate dispersions prepared in Examples 1 to 4 and the polyvinyl alcohol dispersion were prepared by mixing the alumina hydrate solids with the same polyvinyl alcohol solids as in Example 1. The amounts by which the weight ratio becomes 15: 1 were measured, mixed and stirred to obtain a mixed dispersion. The mixed dispersion was applied to a high quality paper (Shiraoi 157, manufactured by Daishowa Paper Co., Ltd.) at a rate of 20 g / m ² air.
An ink receiving layer was obtained by knife coating. The physical properties of the ink receiving layer were measured by the above methods. Table 4 shows the measurement results.

Examples 9 to 12 Freeness (CSF) of 370 m as raw pulp
1 part of hardwood bleached kraft pulp (LBKP) and 410 ml of softwood kraft pulp (NBKP) 2
0 parts were used, and the alumina hydrate prepared in Examples 1 to 4 was used as a filler in an amount of 35% by weight based on the pulp solid content, and a cationized starch (CATOF, manufactured by Oji National Co., Ltd.) was used as a retention aid. 0.3% by weight based on the pulp solid content, and 0.05% by weight of a polyacrylamide-based retention improver (Parfloc FR-X, manufactured by Seiko Chemical Co., Ltd.) immediately before papermaking. , TAPP
Paper was made to a basis weight of 70 g / m ² using an I standard sheetformer. Next, 2% oxidized starch (Nippon Shokuhin Co., Ltd.
MS3800) The solution was applied by a size press to obtain a recording medium. Table 5 shows the measurement results.

Comparative Example 1 According to the method described in Example 1 of JP-A-4-4181, an alumina sol (AS-
2) and polyvinyl alcohol (Kuraray, PVA11)
A recording medium was produced using 7). The zeta potential of the alumina sol was measured by the above method. Further, the alumina sol was concentrated to a solid concentration of 15%, and the viscosity was measured. Table 6 shows the physical property values.

Comparative Example 2 According to the method described in Example 4 of JP-A-4-4181, an alumina sol (AS-
A recording medium was produced using the same polyvinyl alcohol as in 3) and Comparative Example 1. Table 6 shows the physical property values.

Comparative Example 3 According to the method described in Example 1 of JP-A-3-143678, alumina sol (manufactured by Nissan Chemical
0) and the same polyvinyl alcohol as in Comparative Example 1 were used to make a recording medium. Table 6 shows the physical property values.

Comparative Example 4 An alumina sol was prepared according to the method described in Example 1 of JP-A-5-32037. A recording medium was prepared using the alumina sol and the same polyvinyl alcohol as in Comparative Example 1. Table 6 shows the physical property values.

[0080]

[Table 1]

[0081]

[Table 2]

[0082]

[Table 3]

[0083]

[Table 4]

[0084]

[Table 5]

[0085]

[Table 6]

[0086]

【The invention's effect】

1) By having two or more pore size distribution maxima in the same pigment or ink receiving layer, the function of pores can be separated.

2) Since the dye in the ink can be efficiently absorbed by the pores having a relatively small diameter, it is possible to obtain a color image having good resolution and sufficient density.

3) 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.

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

5) Since the dispersibility is good, the viscosity can be reduced even with a dispersion having a high solid content.

6) Since the dispersibility is good even in the neutral region where the pH is around 7, 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.

FIG. 2 is a view showing an X-ray diffraction image of alumina hydrate used in the present invention.

FIG. 3 is a photograph as a drawing showing the particle structure of alumina hydrate used in the present invention.

FIG. 4 is a photograph substituted for a drawing showing the particle structure of alumina hydrate in the ink receiving layer as viewed from the cross section of the ink receiving layer according to the present invention.

FIG. 5 is a view showing a pore size distribution of alumina hydrate of Example 1 of the present invention.

FIG. 6 is a diagram showing an isothermal adsorption curve of alumina hydrate of Example 1 of the present invention.

[Description of Signs] 1 Base material 2 Ink receiving layer

Claims (33)

(57) [Claims] 1. A Oite the pore radius distribution, and 100Å or less
A recording medium comprising an alumina hydrate having a maximum in the range of 100 to 200 ° . Hey 2. A pigment and a recording medium provided on a substrate an ink-receiving layer containing a binder, wherein the alumina hydrate as a pigment, an ink-receiving layer on the pore radius distribution
A recording medium having a maximum in the range of 100 ° or less and 100 to 200 ° . To 3. A fibrous material, Oite the pore radius distribution,
A recording medium characterized by internally adding an alumina hydrate having a maximum of 100 ° or less and a range of 100 to 200 ° . 4. The radius of the alumina hydrate is 100 ° or less.
4. The method according to claim 1, wherein the maximum of
Recording medium. 5. An ink receiving layer having a radius of 100 ° or less.
3. The method according to claim 2, wherein the maximum is in the range of 10 to 60 [deg.].
Recording medium. 6. The alumina hydrate having a pore volume of 0.4 to 0.4.
The recording medium according to claim 1, wherein the recording medium is 0.6 cc / g. 7. The ink receiving layer having a pore volume of 0.4 to 0.1.
The recording medium according to claim 2, wherein the recording medium is 6 cc / g. 8. pore volume of pores having a maximum value below 100Å of the alumina hydrate is 0.1-1 of the total pore volume
The recording medium according to any one of claims 1, 3 and 4 is 0%. 9. pore volume of pores having a maximum value below 100Å of the ink receiving layer is 0.1 to 10 of the total pore volume
The recording medium according to claim 2, wherein the recording medium is%. 10. The ink receiving layer has a total pore volume of 8c.
The recording medium according to claim 2, wherein the recording medium has a c / m ² or more. 11. A relative pressure difference (ΔP) between adsorption and desorption at an adsorption gas amount of 90% of the maximum adsorption gas amount obtained from an isothermal nitrogen adsorption / desorption curve of the alumina hydrate is 0.2 or less. 9. The recording medium according to claim 1, 3, 4, or 8. 12. 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 0.2 or less. The recording medium according to any one of claims 2, 5, and 9. 13. The recording medium according to claim 1, wherein the alumina hydrate is an amorphous compound. 14. The alumina hydrate is a tabular alumina hydrate having an average aspect ratio of 3 to 10.
A recording medium according to claim 1. 15. The recording medium according to claim 14, wherein the flat alumina hydrate has a BET specific surface area of 70 to 300 m ² / g. 16. The recording medium according to claim 14, wherein the average aspect ratio of the flat surface of the flat alumina hydrate is 0.6 to 1.0. 17. The alumina hydrate having 10 hydroxyl groups.
^The recording medium according to any one of claims 1 to 3 , wherein the number is ²⁰ pieces / g or more. 18. Any zeta potential at pH6 of the alumina hydrate of claims 1 to 3 is at least 15mV
The recording medium according to any. 19. The ratio between the alumina hydrate and the binder
3. The coating according to claim 2, wherein the combination is in the range of 1: 1 to 30: 1.
recoding media. 20. The ratio between the alumina hydrate and the binder
3. The coating according to claim 2, wherein the combination is in the range of 5: 1 to 25: 1.
recoding media. 21. The alumina hydrate is represented by the following formula:
The recording medium according to any one of claims 1 to 20, wherein: A
l _Two O _3-n (OH) _2n ・ MH _Two O (Where n is an integer of 0 to 3)
Represents a number and m represents a value of 0 to 10) 22. An ink jet recording apparatus according to claim 1.
22. The recording medium according to any one of claims to 21. 23. The nitrate containing 0.1 to 1.0 wt%, and Oite the pore radius distribution, 100 Å or less and 100
When the alumina hydrate was dispersed at a solids concentration of 15 wt% in deionized water having a maximum in the range of ～200A, viscosity, temperature 20 ° C., as measured at a shear rate of 7.9 sec ^-1 75C
A dispersion of alumina hydrate having a PS or less. 24. The nitrate containing 0.1 to 1.0 wt%, and Oite the pore radius distribution, 100 Å or less and 100
When an alumina hydrate having a maximum in the range of ~200Å dispersed at a solids concentration of 20 wt% in deionized water, viscosity, measured at a temperature 20 ° C., shear rate 10.2 sec ^-1 10
A dispersion of alumina hydrate having a CPS of not more than 0. 25. The nitrate containing 0.1 to 1.0 wt%, and 100 and 100Å or less in a pore radius distribution
When dispersed at a solids concentration of 25 wt% in deionized water an alumina hydrate having a maximum in the range of 200 Å, viscosity,
500C measured at a temperature of 20 ° C and a shear rate of 10.2 sec- ¹
A dispersion of alumina hydrate having a PS or less. 26. The dispersion according to claim 23, wherein the dispersion is a dispersion of a pigment for producing a recording medium. 27. A method according to claim 27, further comprising: ejecting a small droplet of the ink through the fine hole.
In the ink jet recording method for printing by applying to a recording medium, according to claim 1 to 22 noise as a recording medium
An inkjet recording method using the recording medium according to any one of the above. 28. The ink jet recording method according to claim 27 , wherein the ink is ejected by applying thermal energy to the ink. 29. Printed matter obtained by forming an image on the recording medium according to any one of claims 1 to 22 . 30. In the pore radius distribution, 100 ° or less
Hydration with a maximum in the range of 100 to 200 °
Is applied to the substrate, or
It is characterized by being added to the slurry containing the substance and making paper.
Manufacturing method of a recording medium to perform. 31. A dispersion comprising the alumina hydrate
0.5 to 60 g / m in terms of dry solids on the material ^Two In the range
The method for manufacturing a recording medium according to claim 30, wherein the method is applied. 32. A dispersion comprising the alumina hydrate
5-45 g / m in terms of dry solids on the material ^Two Range of application
31. The method for manufacturing a recording medium according to claim 30, wherein: 33. A radius of 100 ° or less of the alumina hydrate
31. The method according to claim 30, wherein the lower maximum is in the range of 10-60 °.
Manufacturing method of a recording medium.