JP2714351B2 - 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.
An ink jet recording method using the recording medium, printed matter and A
The present invention relates to a dispersion of lumina hydrate , and particularly relates to a recording medium having high image density, clear color tone, high resolution, and excellent ink absorption capacity, and a method for producing the recording medium.
Method, an inkjet recording method using this recording medium ,
The present invention relates to a printed material and a dispersion liquid 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 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.

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

Further, US Pat. No. 4,374,804
No. 5,104,730, JP-A-58-110287, and JP-A-4-37576, it is also possible to form a multi-layer ink receiving layer using a silica or alumina material. ing.

However, the conventional recording medium has the following problems.

1) There is a problem that the viscosity of the dispersion liquid increases with time and coating cannot be performed, so that the solid content concentration of the liquid cannot be increased.
Japanese Patent No. 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 the ink receiving layer and a decrease in water resistance, and no sufficient improvement has been made.

2) There is a problem that the solid content of the liquid cannot be increased because the viscosity of the dispersion liquid of the pigment or the like is high and the coating liquid cannot be applied due to increase with time.
No. 985 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.

3) There is a problem that the ink dye is not sufficiently adsorbed and the printed ink dye is not fixed, so that the dye moves with the lapse of time to change the resolution and color, thereby deteriorating the image quality. For the solution

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. H07-107, since each ink dye (cyan, magenta, yellow, and black) and the ink solvent are selectively adsorbed to pores having a specific diameter, print bleeds when the ink composition changes. Will be.

5) 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, beading occurs due to insufficient absorption of the solvent but good absorption of the dye. 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 does not move in the horizontal direction. This is a phenomenon in which the image moves in a regular manner, and as a result, agglomeration occurs between adjacent dots, resulting in unevenness in image density.

6) In printing a color image, the amount of ink is large, so that the printed ink does not completely absorb in the pores and overflows onto the surface of the ink receiving layer, causing bleeding and poor print quality. I will.

7) 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, an output image may be damaged by contact.

8) US Pat. No. 4,780,356 and US Pat. No. 4,780,356 for improving 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.

9) JP-A-3-281384 discloses that
An alumina hydrate that forms a hair-like aggregate having a columnar shape with an 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. Therefore, the pore diameter tends to be narrower and the pore diameter distribution tends to be narrower. As a result, there is a problem that beading occurs as described above.

[0016]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a recording medium which satisfies both an ink absorbing property and a dye absorbing property. To provide an ink jet recording method using the same.

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

[0018]

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

That is, according to the present invention, titanium dioxide is used in an amount of 0.01 to
A recording medium characterized by containing 1.00% by weight of alumina hydrate.

In the present invention, titanium dioxide may be used in an amount of 0.01 to 0.01.
A recording medium comprising an ink receiving layer containing 1.00% by weight of alumina hydrate provided on a base material.

Further, the present invention is a recording medium characterized in that an alumina hydrate containing 0.01 to 1.00% by weight of titanium dioxide is internally added to a fibrous substance.

Further, the present invention provides a composition containing 0.1 to 1.0% by weight of nitrate and 0.01 to 1.00 weight of titanium dioxide.
% Of alumina hydrate containing 1 % by weight in deionized water
The viscosity when dispersed at 5% by weight is 20 ° C., and the shear rate is 7.
It is 75 CPS or less measured at 9 sec ^-1 , contains 0.1 to 1.0% by weight of nitrate, and contains 0.1% of titanium dioxide .
When the alumina hydrate containing 0.1 to 1.00% by weight is dispersed in ion-exchanged water at a solid concentration of 20% by weight, the viscosity is 20%.
100 CPS or less as measured at 10.degree. C. and a shear rate of 10.2 sec @ ^-1 or containing 0.1 to 1.0% by weight of nitrate and 0.01 to 1.00% by weight of titanium dioxide. When the alumina hydrate is dispersed in ion-exchanged water at a solid concentration of 25% by weight, the viscosity is 20 ° C., and the shear rate is 10.2 seconds.
A dispersion of alumina hydrate, characterized in that the dispersion is not more than 500 CPS as measured at ^-1 .

Still further, according to the present invention, in 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, the recording medium is used as the recording medium. This is an inkjet recording method.

In the present invention, by adding 0.01 to 1.00% by weight of titanium dioxide to alumina hydrate,
There is an advantage that both characteristics of dispersibility and dye adsorbability in the ink, which were conventionally difficult, can be further improved as compared with the conventional alumina hydrate.

The recording medium of the present invention is a recording medium containing, as an essential component, an alumina hydrate containing at least the above-mentioned specific content of titanium dioxide.
A structure in which the titanium dioxide-containing alumina hydrate is internally added to the paper from the stage of preparing the raw material of the sheet, or FIG.
As shown in (1), the ink receiving layer mainly containing the above-mentioned alumina hydrate containing titanium dioxide and a binder is formed as a single layer on a substrate. Alumina hydrate has a positive charge, so the ink dye can be fixed well and an image with good coloring can be obtained. In addition, brown discoloration and lightfastness of black ink, which have conventionally been generated by using silica compounds, It is most preferable as a material used for the ink receiving layer because there is no problem such as the above.

The alumina hydrate used in the present invention is most characteristic in that it contains titanium dioxide in a specific content ratio. The content ratio of alumina hydrate is 0.01 to 1.0.
0% by weight, more preferably 0.13 to 1.0%.
0% by weight. Further, the titanium dioxide preferably has a valence of +4.

According to the knowledge of the present inventor, the titanium dioxide contained is present on the surface of the alumina hydrate as ultrafine particles which are not observed when observed with an electron microscope at a magnification of 500,000. Thus, when the dye in the ink is adsorbed, it functions as an adsorption point. I'm not sure why,
YANG et al. (React Kinet CatalLe
TT, 46 [1], 179-186, 1992), the addition of titanium dioxide generates a twisted site containing Al ³⁺ having a strong electron accepting property, thereby improving dye adsorption. This is presumed to be due to a coordination bond between the titanium ion of titanium dioxide and the dye.

Further, according to the findings of the present inventor, in observation of ESCA, titanium has a valence of +4 from the value of the binding energy. Further, since there is no split between the peaks of titanium 3P and aluminum 2P, there is no interaction between titanium and aluminum. That is, titanium dioxide exists in isolation without interaction between titanium and aluminum. Further, when the surface of the alumina hydrate containing titanium dioxide is etched with argon, the amount of titanium is reduced by half in about 100 seconds of etching time, and no titanium is detected in about 500 seconds of etching time. Thus, titanium dioxide is present only in the vicinity of the particle surface without affecting the surface charge of the alumina hydrate due to the conditions of valence and peak splitting, and the dispersibility of the alumina hydrate is not impaired.

If the valence of titanium dioxide is smaller than +4, the titanium dioxide acts as a catalyst by light irradiation, and the binder is deteriorated, so that cracks and powder fall easily occur. In the alumina hydrate used in the present invention, titanium dioxide may be contained only in the vicinity of the surface of the alumina hydrate particles, or may be contained up to the inside. Further, the content may change from the surface to the inside. As shown in Examples of the present invention described below, when titanium dioxide is contained only in the vicinity of the surface, the properties of the bulk inside the alumina hydrate are easily maintained in the vicinity of the surface. It is more preferable because it 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 contained therein, titanium dioxide is most preferable from the viewpoint of the ink dye adsorbing property and dispersibility. Although the above metal oxides are often colored, titanium dioxide is colorless and is therefore preferable from this point.

The alumina hydrate containing titanium dioxide used in the present invention is preferably an alumina hydrate having an amorphous structure, 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 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.

The above alumina hydrate can be produced by a known method such as hydrolysis of aluminum alkoxide and hydrolysis of sodium aluminate. As a method for producing alumina hydrate containing titanium dioxide, a method of producing a mixture of aluminum alkoxide and titanium alkoxide by hydrolysis is most preferable because the particle diameter of titanium dioxide is small and control is easy. The particle diameter and the shape by this method are examined by, for example, Ni / Al ₂ O ₃ catalyst by the alkoxide method, at 327, 1985, edited by Surface Science (ed. By Kenji Tamaru), Gakkai Shuppan Center. 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.

Materials in which a variety of materials are supported on the surface of particles such as alumina are widely known in the field of catalysts. Since titanium dioxide has poor solubility in solvents such as water, it is extremely difficult to support it on alumina or the like. A method of supporting titanium on a particle surface of alumina hydrate as a soluble salt is known, but it is difficult to convert a titanium compound supported on the surface of alumina hydrate to titanium dioxide, and titanium It is also difficult to remove the counter ion component that constituted the salt. In general, the supported titanium compound has a valence of less than +4, and the ESCA is similar to the titanium dioxide-containing alumina hydrate of the present invention.
The valence of titanium examined in the above does not become +4.

The shape of the titanium dioxide-containing alumina hydrate used in the present invention is preferably a flat plate having an average aspect ratio of 3 to 10 and an aspect ratio of the flat plate surface of 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 titanium dioxide-containing 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 titanium dioxide-containing 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, Ap.
plied Catalysis, Vol. 74, 29-3
6, 1991), it is generally known that there are cilia-like and other shapes.

According to the findings of the present inventors, among alumina hydrates, a plate-like shape has better dispersibility than a hairy bundle (ciliform), and when an ink receiving layer is formed, the shape of FIG. As shown in the drawing-substitute photograph (electron micrograph: magnification of 50,000 times), the orientation of the alumina hydrate particles is random, so that the pore size distribution is broadened, 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.

B of the above-mentioned alumina hydrate containing titanium dioxide
The ET surface area, the pore size distribution, the pore volume, and the isothermal adsorption / desorption curve of the alumina hydrate and the ink receiving layer containing the alumina hydrate as described below can be simultaneously determined by a nitrogen adsorption / 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. When the BET specific surface area is smaller than the lower limit of the above range, the pore size distribution is biased toward the larger side and the dye in the ink cannot be sufficiently absorbed and fixed. When the BET specific surface area is larger than the upper limit of the above range, the pigment is dispersed. There is a possibility that the coating cannot be performed well 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, such as the Bayer method or the alum pyrolysis method. Any of these methods 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 the alkoxide. 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 higher than 8, the alumina hydrate finally obtained becomes crystalline.

In the first aspect of the present invention, the hydrated alumina containing titanium dioxide and the recording medium using the hydrated alumina have a large half width of the pore radius distribution. 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 size grow, the gaps between the primary particles forming the pores become uniform, and the pore radius distribution becomes narrow. Conversely, if the aging time is shorter than this condition, primary particles of alumina hydrate having a relatively non-uniform particle size will grow, and the size of the gap between the primary particles forming pores in particular will also be irregular, and as a result, It is considered that the pore radius distribution is widened. The correlation between the degree of unevenness of the primary particles and the width of the pore radius distribution is not clear. 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.

In the first aspect of the present invention, the titanium dioxide-containing alumina hydrate has a wide half-value width of the pore radius distribution as described later. Such titanium dioxide-containing alumina hydrate is dispersed up to the primary particles in the coating dispersion, but a wide pore radius distribution is obtained by dispersing titanium dioxide-containing alumina hydrate and coating on a substrate. Even if the ink receiving layer is formed through a drying step, a substantially wide distribution of pore diameters is maintained. The reason for this is not clear, but if it is dared to facilitate the understanding of the present invention, the pore structure is mainly formed by the gaps between the primary particles of alumina hydrate, and the plate-like alumina hydrate is formed. It is presumed that the particles are oriented in random directions in the ink receiving layer, or that a wide pore radius distribution due to the non-uniform particle size of alumina hydrate is maintained in the ink receiving layer. Is done.

The average pore radius of the ink receiving layer is 20 to 200 ° and the half width of the pore radius distribution is 2
0 to 150 ° is preferable, and more preferably 80 to 150 °
範 囲 range. Here, the half width of the pore radius 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 upper limit of the above range, the adsorption and fixation of the dye in the ink is deteriorated, and the image is easily blurred. When the average pore radius is smaller, the ink absorption is poor. Beading occurs. If the half width is outside the above range, the absorption of the dye or the ink component in the ink will be poor. The pore radius distribution of the alumina hydrate has an average pore radius of 20 to 20 as in the ink receiving layer.
At 0 °, the half width of the pore radius distribution is preferably from 20 to 150 °. Since the pore radius distribution of the ink receiving layer depends on the pore radius distribution of the alumina hydrate, if it is outside the above range, the pore radius distribution of the ink receiving layer may be within the above specified range. Can not.

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, ink overflows from the ink receiving layer and bleeding occurs in the image. The pore volume of alumina hydrate is 0.4 to 0.6 as in the ink receiving layer.
A range of 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 the second aspect of the present invention, the titanium dioxide-containing alumina hydrate has two or more maxima in the pore radius distribution. The alumina hydrate obtained in the same manner as in the above method grows particles through the hydrothermal synthesis step. When the primary particles of the alumina hydrate having a relatively uniform particle size grow and the aging time is longer than the condition in which the pore size distribution becomes narrower, the alumina hydrate having a bimodal pore radius distribution. Things are obtained. It is preferable that the sol obtained here is dried once and made into a powder form in the same manner as in the first embodiment, and then water is added to make a dispersion liquid, since the dispersibility is improved.

The alumina hydrate obtained by this method has two or more maxima in the pore radius distribution. The reason for having two or more maxima is that the pore structure is mainly formed by gaps between primary particles of alumina hydrate. Since the alumina hydrate of 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, the gap between the portions where the primary particles overlap in the main plane direction of the flat plate, This is considered to be due to the occurrence of a gap between the main plane and the portion where the end faces overlap. 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 titanium dioxide-containing alumina hydrate according to the second embodiment of the present invention has two or more maxima in the pore radius distribution. Such titanium dioxide-containing alumina hydrate is dispersed up to the primary particles in the coating dispersion,
The pore radius distribution having two or more maxima is maintained even when the ink receiving layer is formed. The reason for this is that, as shown in the drawing substitute photograph of FIG. 5, in the ink receiving layer, the primary particles are each oriented in a random direction, and the primary particles are mainly formed of flat plates as in the case of alumina hydrate. Two or more local maxima of the pore radius distribution resulting from the generation of a gap between portions where the binder overlaps in the plane direction via the binder and a gap between the end face and the portion where the main plane or the end face overlaps via the binder. We speculate that the structure is maintained in the ink receiving layer.

JP-A-58-110287 discloses a recording sheet having a pore diameter peak of 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.

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 relatively small maxima is preferably a pore radius of 100 ° or less, and a pore radius of 10 to 60 ° is preferable because the dye adsorbability is remarkably improved. The relatively large maximum is preferably in the range of a pore radius of 100 to 200 ° from the viewpoint of increasing the solvent absorption rate. If the relatively small maximum is larger than the above range, the adsorption and fixation of the dye in the ink is deteriorated, and the image bleeds and beading occurs. When the relatively large maximum is smaller than the lower limit of the above range, the absorption of the solvent component in the ink becomes poor, the drying of the ink becomes poor, and the ink receiving layer surface does not dry when printed and carried out of the apparatus, If the relatively large maximum 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 radius distribution, one of the relatively small maxima is preferably a pore radius of 100 ° or less, more preferably 1 ° or less, like the ink receiving layer.
0-60 °. A relatively large maximum has a pore radius of 100
It is preferably in the range of ~ 200 °. The pore structure of the ink receiving layer is formed by the primary of alumina hydrate as described above, but since this pore structure has already formed the property in alumina hydrate, the pore radius distribution When the maximum value is out of the above range, the pore radius distribution of the ink receiving layer cannot be within the above specified range.

The pore volume of the ink receiving layer is 0.1 to 1.0.
A range of cc / g is preferred. More preferably 0.4 to
It is in the range of 0.6 cc / g. If the pore volume of the ink receiving layer is larger than the above range, the ink receiving layer cracks,
If powder fall occurs and is smaller than the above range, ink absorption will be poor. Further, the pore volume of the ink receiving layer is 8
It is preferably at least cc / m ² . Below this range, particularly when multicolor printing is performed, ink overflows from the ink receiving layer and bleeding occurs in the image. The pore volume of the pore having a maximum value at a pore radius of 100 ° or less is 100% in the pore distribution.
Å 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 is shown below.
The pore volume having a maximum value at a pore radius of 100 ° or less is
It is preferably from 0.1 to 10% of the total pore volume, more preferably from 1 to 5%.

The pore volume of alumina hydrate is preferably in the range of 0.1 to 1.0 cc / g, more preferably 0.4 to 0.6 cc / g, as in the ink receiving layer. Further, the pore volume of the pore having the maximum value at a pore radius of 100 ° or less is preferably 0.1 to 10% of the total pore volume, more preferably 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 first and second embodiments 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 mixed on a substrate is provided. Liquid) to form an ink receiving layer. 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, the coating apparatus, the coating head, the coating amount,
Since it varies depending on various manufacturing conditions such as the amount of the drying air, the temperature, and the blowing direction, it is necessary to control the manufacturing conditions in an optimum range in order to obtain the characteristics of the ink receiving layer according to the present invention.

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 by 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. If it exceeds the above range, drying of the ink after printing becomes poor. Incidentally, Japanese Patent Application Laid-Open No.
According to Japanese Patent No. 5588, 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, a gourd shape with a constricted middle part, and a winding shape. It is described that the shape and the like are not preferable from the viewpoint of the absorption rate, but there is no description about a specific method for measuring actual physical property values and the like.

Further, in the recording medium of the present invention, the recording medium having the ink receiving layer containing the alumina hydrate includes:
The 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 and desorption curve of alumina hydrate derived by the nitrogen adsorption and desorption method 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.
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 titanium dioxide-containing alumina hydrate used in the recording medium of the present invention is 10 ²⁰ /
g or more. If it is less than this value, it is impossible to increase the solid concentration of the dispersion in which the alumina hydrate containing titanium dioxide 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 titanium dioxide-containing alumina hydrate used in the present invention can be determined with a zeta potentiometer. JP-A-60-232990 discloses that an alumina compound has a positive charge, and furthermore, the values of zeta potential are disclosed in Examples, but specific measurement methods and conditions are described. Absent. The zeta potential value depends on the cell, electrode structure, applied voltage, solids concentration, dispersion pH, dispersant and additives used in the measurement device, so measurement is not performed under the same measurement conditions and equipment. Cannot be directly compared with the absolute value.

The alumina hydrate used in the present invention preferably has a zeta potential of not less than 15 mV at pH 6 in a 0.1% by weight aqueous dispersion without adding a dispersant and additives. 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, the above-mentioned specific titanium dioxide-containing alumina hydrate containing 0.1 to 1.0% by weight of nitrate is preferably used in the present invention.
The viscosity of the dispersion dispersed in ion-exchanged water at a concentration of 75% by weight was measured at a dispersion temperature of 20 ° C. and a shear rate of 7.9 sec ^−1.
PS or less, particularly preferably 30 CPS or less. Also, preferably, the same nitrate group as described above is used in an amount of 0.1 to 0.1.
Alumina hydrate containing 1.0% by weight contained a solid content of 20%.
The viscosity of the dispersion dispersed in ion-exchanged water at 10% by weight was measured at a dispersion temperature of 20 ° C. and a shear rate of 10.2 sec ^−1.
0 CPS or less, particularly preferably 80 CPS or less. Furthermore, the viscosity of the dispersion obtained by dispersing the same hydrate of alumina containing 0.1 to 1.0% by weight of nitrate in ion-exchanged water at a solid concentration of 25% by weight has a dispersion temperature of 2%.
It is preferably 500 CPS or less, particularly preferably 460 CPS or less, measured at 0 ° C. and a shear rate of 10.2 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 dispersion of the titanium dioxide-containing alumina hydrate can be measured using, for example, a rotational viscometer such as a B-type viscometer.

As a result of comparing and examining the conventional example using the above-mentioned pseudo-boehmite and the present invention, the difference is as follows.

The above prior art discloses an alumina hydrate having a pseudo-boehmite structure. It is also disclosed that an additive such as silica, boria, titania, and magnesia is added to alumina hydrate. In contrast, the present inventors have found that alumina hydrate containing titanium dioxide has an effect of improving both dye adsorption and dispersibility in ink.

The titanium dioxide-containing alumina hydrate is as follows:
By adsorbing on the strong electron-withdrawing Al ³⁺ produced by the addition of titanium dioxide or by forming a coordination bond on the titanium ions themselves, the dye is more dyeable than alumina hydrate without the addition of titanium dioxide. Is improved. FIG. 2 schematically shows the state of titanium in the pores and the state of exposure when titanium dioxide is added (mixed) and when titanium dioxide is contained. In the mixed system, the titanium dioxide exposed inside the pores is a part, but in the containing system, the titanium dioxide is exposed entirely inside the pores. Even though titanium dioxide is present in the same proportion, the amount of titanium dioxide exposed is greater for the system of the present invention.

Further, in the titanium dioxide-containing alumina hydrate used in the present invention, ultrafine titanium dioxide that cannot be observed even by an electron microscope exists near the very surface of the alumina hydrate. Since the surface area of titanium is considerably large and the adsorption site is much larger than that of the mixed system, the effect on the adsorbing power of the ink dye is greatly exhibited.

In the alumina hydrate mixed with titanium dioxide, since the surface charges of the alumina hydrate and titanium dioxide are opposite in sign, they are likely to cancel each other and lose the surface charge. Therefore, the zeta potential of the dispersion liquid is small, and the dispersion liquid is easily aggregated. On the other hand, in the titanium dioxide-containing alumina hydrate used in the present invention, the surface area of titanium dioxide inside the pores becomes considerably large due to the presence of ultrafine titanium dioxide near the very surface of the alumina hydrate, And the influence on the structure of alumina hydrate is small. Also, there is an effect that the decrease in the surface charge of the alumina hydrate is extremely small. Furthermore, in the present invention, since titanium dioxide is present only near the surface of the alumina hydrate, the effect of easily maintaining the bulk properties inside the alumina hydrate also has the effect of less affecting the surface charge.

In the above-mentioned conventional example, a hair bundle-like pseudo-boehmite sol and a method for producing an ink receiving layer using the same are described. In contrast, in the present invention, the titanium dioxide-containing tabular amorphous alumina hydrate is preferably produced by hydrolyzing long-chain aluminum alkoxide and titanium alkoxide. A small amount of alumina hydrate can be easily obtained. In this step, the alumina hydrate easily becomes tabular grains and the shape can be easily controlled. Further, since titanium dioxide is present only in the vicinity of the particle surface, the dispersibility is extremely high as compared with conventionally known hairy bundles of alumina hydrate. Furthermore, the dispersion of titanium dioxide-containing alumina hydrate is dried and powdered once without preparing a dispersion (particularly a dispersion for coating) directly from the sol, so that a dispersion having a high solid content and a low viscosity can be obtained. A liquid can be obtained easily.

In the recording medium of the present invention, the binder used in combination with the titanium dioxide-containing 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),
Starch or its modified product (oxidized or etherified), gelatin or its modified product, casein or its modified product, carboxymethylcellulose, gum arabic, cellulose derivatives such as hydroxyethylcellulose, hydroxypropylmethylcellulose, SBR latex, NBR latex, methyl methacrylate- Conjugated diene-based copolymer latex such as butadiene copolymer, functional group-modified polymer latex, vinyl-based copolymer latex such as ethylene-vinyl acetate copolymer, polyvinylpyrrolidone, maleic anhydride or its copolymer, acrylic acid Ester copolymers and the like 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 is 1: 1 to 30: 1,
More preferably, it can be arbitrarily selected from the range of 5: 1 to 20: 1. If the amount of the binder is less than the above range, the mechanical strength of the ink receiving layer is insufficient, cracking or powder drop occurs, and if it is more than the above range, the pore volume is reduced and the ink absorption is poor. Become.

Pigments and binders may include pigment dispersants, thickeners, pH adjusters, lubricants, fluidity modifiers, surfactants, defoamers, waterproofing agents, foam inhibitors, mold release agents, if necessary. An agent, a foaming agent, a penetrant, 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, papers such as appropriately sized paper, non-sized paper, resin-coated paper using polyethylene or the like, sheet-like substances such as thermoplastic films, and fabrics Can be used. For thermoplastic films, polyester, polystyrene, polyvinyl chloride, polymethyl methacrylate, cellulose acetate,
A transparent film of polyethylene, polycarbonate, or the like, or an opaque sheet formed by filling with a pigment or fine foaming can also be used.

The dispersion of alumina hydrate 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. After that, add a separately prepared binder dispersion, disperse as necessary,
A treatment such as heating and defoaming is performed to obtain a final dispersion for coating.

In the recording medium having the ink receiving layer of the present invention, the method for forming the ink receiving layer on the substrate is as follows. A method of coating and drying on the top can be adopted. As a coating method, generally used blade coater, air knife coater, roll coater brush coater, curtain coater, bar coater,
A gravure coater, a spray device, or the like can be used. The coating amount of the dispersion is 0.5 to 60 in terms of dry solid content.
g / m ^2, more preferably from 5~45g / m ^2. If necessary, the surface smoothness of the ink receiving layer can be improved by using a calender roll or the like after coating.

Further, the recording medium of the type in which the alumina hydrate of the present invention is added is an alumina hydrate (a dispersion thereof).
Can be produced by an internal addition method in which the compound is added to a slurry containing a fibrous substance in a papermaking process or the like. In such an internal addition method, a paper strength improver, a retention improver, and a coloring agent can be added as necessary. As the retention enhancer, it is possible to select or use in combination a cationic retention enhancer such as cationized starch and dicyandiamide formalin condensate and an anionic retention enhancer such as anionic polyacrylamide and anionic colloidal silica. it can.

On the other hand, the ink used when 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 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. 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 those having 1 carbon atom such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol and isobutyl alcohol. To 4, alkyl alcohols, dimethylformamide, amides such as dimethylacetamide, acetone, ketone or ketone alcohols such as diacetone alcohol, ethers such as tetrahydrofuran and dioxane, polyethylene glycol, polyalkylene glycols such as polypropylene glycol, Ethylene glycol, propylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol, etc. Alkylene glycols in which the alkylene group contains 2 to 6 carbon atoms, lower polyhydric alcohols such as glycerin, ethylene glycol methyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, triethylene glycol monomethyl ether, and triethylene glycol monoethyl ether. And alkyl ethers.

Of these many water-soluble organic solvents,
Polyhydric alcohols such as diethylene glycol, and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl ether and triethylene glycol monoethyl ether are preferred. Polyhydric 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 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, a viscosity modifier, a surfactant, a surface tension modifier, p
Additives such as an H adjuster and a specific resistance adjuster can be used.

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, an ink jet method in which a rapid volume change is caused in the ink that has been subjected to the action of thermal energy by the method described in JP-A-54-59936, and the ink is ejected from a nozzle by the action force due to the state change Can be used effectively.

[0083]

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) Analysis of the Amount of Titanium Dioxide The content of titanium dioxide in the entire alumina hydrate was determined by melting the alumina hydrate in a borate and by the ICP method (SPS4000, manufactured by Seiko Electronics Co., Ltd.). The distribution of titanium dioxide in alumina hydrate was determined by ESCA (Surface S
Model made by scienceInstruments, Inc.
2803). Etching the surface of alumina hydrate with argon ions for 100 seconds and 500 seconds,
The change in content was investigated. The etching conditions were an argon pressure of 5 × 10 ⁻⁴ Pa, a voltage of 3 kV, and a current of 3 mA (DC).

2) BET Specific Surface Area, Pore Size Distribution, Pore Volume, Isothermal Desorption Curve Characteristics After the recording medium having the receptor layer formed on the alumina hydrate or PET film is sufficiently heated and degassed, It measured using the nitrogen adsorption desorption method. (Autosorb 1 manufactured by Cantachrome Co., Ltd.) The BET specific surface area was calculated using the method of Brunauer et al. (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.

3) X-ray diffraction image An X-ray diffraction apparatus (manufactured by Rigaku Corporation) was used.

4) Observation of Shape of Alumina Hydrate (Aspect Ratio, Aspect Ratio, Particle Shape) Alumina hydrate was dispersed in ion-exchanged water and dropped on a collodion film to prepare a sample for measurement. This sample was observed with a transmission electron microscope (H-500, manufactured by Hitachi, Ltd.).

5) Number of hydroxyl groups 1 g of alumina hydrate was weighed out and titrated with triethylaluminum.

6) Zeta potential Alumina hydrate was added to ion-exchanged water at a solid content of 0.1% by weight.
After dispersing so as to obtain
H was adjusted to 6 and measured. (Brook Haven, B
i-ZETA plus, liquid temperature 20 ° C, using acrylic cell)

7) Solution viscosity A dispersion having a solid content concentration of alumina hydrate of 15% by weight was prepared, and the dispersion was prepared at a temperature of 20 ° C., manufactured by TOKIMEC, VIS.
It was measured at a shear rate of 7.9 sec ^-1 using a COMTER. Further, a dispersion liquid having a solid content concentration of alumina hydrate of 20 and 25% by weight was prepared, and TOKIM was prepared at a temperature of 20 ° C.
Shear speed 1 using VISCOMTER manufactured by EC
It was measured at 0.2 sec- ¹ .

8) Nitrate The nitrate was extracted from alumina hydrate with hot water, measured by ion chromatography (Hitachi, L-3720), and expressed as a percentage by weight in the alumina hydrate.

9) Printing Characteristics Using an ink jet printer provided with 128 nozzles at a nozzle interval of 16 nozzles per 1 mm for four colors of Y, M, C and Bk, an ink of the following composition was used. Ink-jet recording was performed to evaluate the drying property (absorbency), image density, bleeding, and beading of the ink.

(1) Ink Drying Property After the solid ink of each of Y, M, C, and Bk was printed 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 does not adhere to the finger at 200% of the ink amount, ○ when the ink amount does not adhere to the finger at 100%, and x when the ink adheres to the finger at the same 100%
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 the 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 it did not occur at the ink amount of 200%, it was evaluated as ○. If it did not occur at the ink amount of 100%, it was evaluated as ×.

Ink composition Dye 5 parts Diethylene glycol 15 parts Polyethylene glycol 20 parts Water 70 parts

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

Examples 1 and 2 Aluminum dodexide was prepared by the method described in US Pat. No. 4,242,271. Next, isopropyl titanium (manufactured by Kishida Chemical Co., Ltd.) was mixed in an amount (weight) of 5/1000 of the aluminum alkoxide. The aluminum alkoxide mixture was hydrolyzed by the method described in U.S. Pat. No. 4,202,870 to produce a titanium dioxide-containing alumina slurry. Water was added until the alumina hydrate solids concentration was 7.9%. The pH of the alumina slurry was 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. 75 of this colloidal sol
Spray-dried at ℃ to obtain alumina hydrate. This alumina hydrate was amorphous as shown in the X-ray diffraction image of FIG. The crystal shape was a flat plate shape as shown in the photograph (drawing electron microscope: 60,000 times magnification) of the drawing in FIG. Furthermore, using FE-TEM (Hitachi, HF2000),
The surface of the alumina hydrate was observed at a magnification of 50 times, but no titanium dioxide was observed. The physical properties of the alumina hydrate were measured by the above methods. The results are shown in Table 2, FIG. 6 and FIG.

On the other hand, in the observation of ESCA, titanium is +4 from the value of the binding energy. In addition, there is no interaction between titanium and aluminum because there is no peak splitting in each peak of titanium 3P and aluminum 2P. Titanium dioxide exists in isolation in alumina hydrate. Further, when the surface of the alumina hydrate containing titanium dioxide is etched, the amount of titanium is reduced by half in an etching time of 100 seconds, and titanium is not detected in an etching time of 500 seconds. Therefore, it was found that titanium dioxide was present only near the surface of the alumina hydrate. As a result of etching the alumina surface hydrate with argon ions, titanium dioxide was present only near the surface of the alumina hydrate.

Examples 3 and 4 Aluminum dodecoxide was produced in the same manner as in Example 1. The aluminum alkoxide was hydrolyzed in the same manner as in Example 1 to produce an alumina slurry. The aluminum alkoxide and isopropyl titanium (manufactured by Kishida Chemical Co., Ltd.) were mixed such that the weight mixing ratio became 100: 5. Using the alumina slurry as a core for crystal growth, hydrolysis was carried out in the same manner as in Example 1 to produce a titanium dioxide-containing alumina slurry. Water was added until the alumina hydrate solids concentration was 7.9%. The pH of the alumina slurry was 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. 75 of this colloidal sol
Spray-dried at ℃ to obtain alumina hydrate. Example 1
Similarly to the above, the alumina hydrate was amorphous and had a flat plate shape. The physical properties of the alumina hydrate were measured by the above methods. Table 2 shows the results. As in Examples 1 and 2,
Titanium dioxide was present only near the surface of the alumina hydrate.

Polyvinyl alcohol (Gohsenol 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 above-mentioned alumina hydrate and polyvinyl alcohol solution are weighed in such amounts that the polyvinyl alcohol solid content and the alumina hydrate solid content become 1:10 in weight mixing ratio, mixed and stirred to obtain a mixed dispersion. Was. A 100 μm thick PET
Die coating was performed on a film (Lumirror, manufactured by Toray Industries, Inc.) to obtain an ink receiving layer having a thickness of 30 μm. The drawing substitute photograph (electron micrograph: magnification of 50,000 times) of FIG. 5 is obtained by observing the cross section of the ink receiving layer, and it can be seen that the 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 weight mixing ratio of the titanium dioxide-containing alumina hydrate dispersion described in Examples 1 to 4 and the polyvinyl alcohol dispersion was 15: 1 as in Example 1. The amounts were respectively measured, mixed and stirred to obtain a mixed dispersion. The above mixed dispersion is applied to high quality paper (Shiraoi 157, manufactured by Daishowa Paper).
20 g / m ² air knife coating was performed thereon to obtain an ink receiving layer. Physical property values were measured by the methods described above. Table 4 shows the measurement results.

Examples 9 to 12 Freeness (CSF) 370 m as raw pulp
l of hardwood bleached kraft pulp (LBKP) and softwood kraft pulp (NBKP) of 20 parts, and using the titanium dioxide-containing alumina hydrate described in Examples 1 to 4 as a filler in the pulp solid content Cationized starch (CATOF, manufactured by Oji National Co., Ltd.) as a retention aid, 0.3% by weight based on the solid content of the pulp, and a polyacrylamide-based retention aid immediately before papermaking. (Pearl Floc FR-X, manufactured by Seiko Chemical Co., Ltd.) was added in an amount of 0.05% by weight, and the basis weight was 70 using a TAPPI standard sheet former.
g / m ² . Next, a solution of oxidized starch having a concentration of 2% (MS3800, manufactured by Nippon Shokuhin Co., Ltd.) was adhered using a size press to obtain a recording medium. Physical property values were measured by the methods described above. Table 5 shows the measurement results.

Reference Example 1 An aluminum alkoxide was produced in the same manner as in Example 1. Next, the aluminum alkoxide was hydrolyzed in the same manner as in Example 1 to produce an alumina slurry. The solid content concentration and pH were adjusted in the same manner as in Example 1. A colloidal sol was formed and dried under the same aging conditions as in Example 1 to obtain an alumina hydrate. Example 1
An ink receiving layer was formed in the same manner as described above. Physical property values were measured by the methods described above. Table 6 shows the measurement results.

Reference Example 2 An alumina hydrate was produced in the same manner as in Reference Example 1. 0.15% by weight of the alumina hydrate was mixed with ultrafine titanium dioxide particles (Taika, 150W) to prepare an alumina hydrate dispersion. An ink receiving layer was formed in the same manner as in Example 1. The physical properties of the alumina hydrate and the ink receiving layer were measured by the above methods. Table 6 shows the measurement results.

Reference Example 3 An aluminum alkoxide was produced in the same manner as in Example 1. Example 1 Example 1 was repeated using isopropyl zirconium (manufactured by Kishida Chemical Co.) instead of isopropyl titanium of Example 1.
Were mixed at the same mixing ratio. Next, the aluminum alkoxide mixture was hydrolyzed in the same manner as in Example 1 to produce an alumina slurry. The solid content concentration and pH were adjusted in the same manner as in Example 1. A colloidal sol was formed and dried under the same aging conditions as in Example 1 to obtain an alumina hydrate. An ink receiving layer was formed in the same manner as in Example 1. The physical properties of the alumina hydrate and the ink receiving layer were measured by the above methods. Table 6 shows the measurement results.

REFERENCE EXAMPLE 4 An alumina hydrate and an ink receiving layer were produced in the same manner as in Reference Example 3, except that tetraisopropyloxysilane (manufactured by Kishida Chemical Co., Ltd.) was used instead of isopropyl zirconium in Reference Example 3. The physical properties of the alumina hydrate and the ink receiving layer were measured by the above methods. Table 6 shows the measurement results.

[0108]

[Table 1]

[0109]

[Table 2]

[0110]

[Table 3]

[0111]

[Table 4]

[0112]

[Table 5]

[0113]

[Table 6]

[0114]

The following effects can be obtained by using the recording medium of the present invention.

1) By including titanium dioxide in alumina hydrate, both the adsorptivity and the dispersibility of the dye could be satisfied. Since the dispersibility is good, the viscosity can be reduced even in a dispersion having a high solid content, 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.

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

3) 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.

4) Since titanium dioxide is colorless, the receptor layer is not colored even if added.

5) Since each ink dye and solvent component are selectively adsorbed on pores having a specific diameter, the use of a medium having a wide pore radius distribution makes it less likely to be affected by the ink composition. Therefore, the selectivity to the ink composition is increased.

6) When the same titanium dioxide-containing alumina hydrate or ink-receiving layer has two or more pore radius distribution maxima, the function of pores can be separated. 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 a good resolution and a sufficient density. Since the solvent component can be absorbed quickly, an image with high resolution can be obtained without beading, bleeding, or ink overflow.

[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 cross-sectional view showing a pore portion of a recording medium of the present invention.

FIG. 3 is a view showing an X-ray diffraction image of a titanium dioxide-containing alumina hydrate of Example 1 of the present invention.

FIG. 4 is a photograph as a substitute of a drawing showing the particle structure of titanium dioxide-containing alumina hydrate of Example 1 of the present invention.

FIG. 5 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. 6 is a diagram showing an isotherm adsorption curve of titanium dioxide-containing alumina hydrate of Example 1 of the present invention.

FIG. 7 is a view showing a pore radius distribution of titanium dioxide-containing alumina hydrate of Example 1 of the present invention.

[Explanation of symbols]

 1 base material 2 ink receiving layer

Claims (40)

(57) [Claims] 1. A recording medium comprising an alumina hydrate containing 0.01 to 1.00% by weight of titanium dioxide. 2. A recording medium comprising an ink receiving layer containing alumina hydrate containing 0.01 to 1.00% by weight of titanium dioxide provided on a substrate. 3. The fibrous substance contains 0.01% titanium dioxide.
A recording medium characterized by internally adding an alumina hydrate containing 1.00% by weight. 4. The recording medium according to claim 1, wherein the alumina hydrate is an amorphous compound. Wherein said alumina hydrate, a recording medium according to any one of claims 1 to 4 is a tabular alumina hydrate having an average aspect ratio of 3-10. 6. The recording medium according to claim 5, wherein the average aspect ratio of the flat surface of the flat alumina hydrate is 0.6 to 1.0. 7. The recording medium according to claim 5, wherein the BET specific surface area of the tabular alumina hydrate is in a range of 70 to 300 m ² / g. 8. The alumina hydrate having a hydroxyl group number of 10 ²⁰
The recording medium according to any one of claims 1 to 3 , wherein the number of the recording medium is not less than the number per unit. 9. The recording medium according to any one <br/> of claims 1 to 3 zeta potential is more than 15mV at pH6 of the alumina hydrate. 10. The alumina hydrate has an average pore radius in the range of 20 to 200 ° , and a half-value width of the pore diameter distribution is 2 μm.
The recording medium according to claim 1, wherein the recording medium is in a range of 0 to 150 °. 11. The ink receiving layer having an average pore radius of 2
0 to 200 ° , and the half width of the pore size distribution is 20
3. The recording medium according to claim 2, wherein the angle is in the range of 150 to 150 [deg.]. 12. The alumina hydrate has a pore volume of 0.4 to 0.4.
The recording medium according to claim 10, wherein the content is 0.6 cc / g. 13. The ink receiving layer having a pore volume of 0.4 to 0.4.
The recording medium according to claim 11, which is 0.6 cc / g. 14. The alumina hydrate has a pore radius distribution.
The recording medium according to claim 1 or 3 having Oite two or more maxima. 15. The ink receiving layer according to claim 1, wherein said ink receiving layer has a pore radius distribution .
3. The recording medium according to claim 2, wherein the recording medium has two or more local maxima. 16. The pore radius distribution of the alumina hydrate
The recording medium according to claim 14, wherein the maximum in the range is 100 ° or less and in the range of 100 to 200 °. 17. The ink receiving layer according to claim 1, wherein said ink receiving layer has a pore radius distribution.
The recording medium according to claim 15, wherein the maximum value is in the range of 100 ° or less and 100 to 200 °. 18. A radius of the alumina hydrate of 100 ° or less.
15. The method according to claim 14, wherein the lower maximum is in the range of 10 to 60 degrees.
Recording medium. 19. The ink receiving layer has a radius of 100 ° or less.
16. The method according to claim 15, wherein the maximum of is in the range of 10 to 60 °.
Recording medium. 20. pore volume of the alumina hydrate is 0.
The recording medium according to claim 14, wherein the recording medium is in a range of 4 to 0.6 cc / g. Pore volume of 21. The ink-receiving layer is 0.4
The recording medium according to claim 15, wherein the recording medium is in the range of 0.6 to 0.6 cc / g. 22. The pore volume of pores having a maximum value of 100 ° or less of the alumina hydrate is 0.1% of the total pore volume.
The recording medium according to claim 16, wherein the content is 10% to 10%. 23. The pore volume of pores having a maximum value of 100 ° or less in the ink receiving layer is 0.1 to 0.1% of the total pore volume.
17. The recording medium according to claim 16, which is 10%. 24. The total pore volume of the ink receiving layer is 8c.
The recording medium according to claim 15 or 17 c / m ² or more. 25. 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 alumina hydrate is 0.2 or less. The recording medium according to claim 1. 26. A 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 the ink receiving layer is 0.2 or less. The recording medium according to claim 2. 27. 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. 28. The ratio of 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. 29. The alumina hydrate is represented by the following formula:
A recording medium according to any one of claims 1 to 28. Al _Two O _3-n (OH) _2n ・ MH _Two O (In the formula, n represents an integer of 0 to 3, and m represents a value of 0 to 10.
Represent) 30. An ink jet recording apparatus according to claim 1.
30. The recording medium according to any one of claims to 29. 31. The nitrate containing 0.1 to 1.0 wt%, and a solid concentration of alumina hydrate containing titanium dioxide 0.01 to 1.00% by weight Ion-exchanged water 15 wt% in when dispersed, viscosity, temperature 20 ° C., shear rate 7.
A dispersion of alumina hydrate characterized by having a CPS of 75 CPS or less as measured at 9 sec ^-1 . 32. nitrate was 0.1 to 1.0 wt%, and a solid concentration of alumina hydrate containing titanium dioxide 0.01 to 1.00 wt% ion exchanged water 20 wt% When dispersed at a temperature of 20 ° C. and a shear rate of 1
A dispersion of alumina hydrate, characterized in that it has a viscosity of 100 CPS or less as measured at 0.2 sec ^-1 . 33. nitrate was 0.1 to 1.0 wt%, and a solid concentration of alumina hydrate containing titanium dioxide 0.01 to 1.00 wt% of ion-exchanged water 25 wt% When dispersed at a temperature of 20 ° C. and a shear rate of 1
A dispersion of alumina hydrate, having a CPS of 500 CPS or less as measured at 0.2 sec ^-1 . 34. The dispersion according to claim 31, wherein the dispersion is a pigment dispersion for producing a recording medium. 35. Discharge a small droplet of ink from a fine hole,
In the ink jet recording method for printing by applying to a recording medium, according to claim 1 to 30 noise as a recording medium
An inkjet recording method using the recording medium according to any one of the above. 36. The ink recording method according to claim 35 , wherein thermal energy acts on the ink to eject the ink droplet. 37. A printed matter obtained by forming an image on the recording medium according to any one of claims 1 to 30 . 38. A titanium dioxide of 0.01 to 1.00 weight
% Of the dispersion containing alumina hydrate
Cloth or added to slurry containing fibrous material
And producing the recording medium. 39. 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 38, wherein the method is applied. 40. A dispersion comprising the alumina hydrate
5-45 g / m in terms of dry solids on the material ^Two Range of application
The method for manufacturing a recording medium according to claim 38.