JP2714352B2 - 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 manufacturing 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 alumina hydrate , and particularly to a recording medium having high image density, clear color tone, high resolution, and excellent ink absorption capacity, and a method of manufacturing the recording medium.
Method, an inkjet recording method using this recording medium ,
The present invention relates to a dispersion liquid suitable for producing a printed matter and a 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.

Further, US Pat. No. 4,879,166,
No. 5,104,730, JP-A-2-276670,
JP-A-4-37576 and JP-A-5-32037 propose a recording sheet having a layer using alumina hydrate having a pseudo-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 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.

2) 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 1;
A recording medium having a narrow pore size distribution of 0 to 30 ° is disclosed. In this pore size distribution, beading occurs due to insufficient absorption of the solvent but good absorption of the dye. Here, 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,
This is a phenomenon in which ink dots move irregularly in the horizontal direction, and as a result, agglomeration occurs between adjacent dots, causing unevenness in image density.

3) 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.

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

5) Since the viscosity of the 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.
JP-A-4-67986 discloses a method for lowering the degree of polymerization of a binder polymer. However, there are problems such as poor appearance such as cracking of the ink receiving layer and a decrease in water resistance, and no sufficient improvement has been made.

6) There is a problem that the solid content concentration cannot be increased due to the high viscosity of the dispersion.
No. 5 discloses a method of adding an acid such as a monocarboxylic acid as a dispersant as a countermeasure, but causes production problems such as generation of pungent odor and corrosion. .

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 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.

[0015]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made for the purpose of solving the above-mentioned problems, and has as its object to be able to cope with inks of various compositions, to have excellent ink absorbability, and to prevent printing bleeding. Another object of the present invention is to provide a recording medium capable of suppressing the occurrence of beading and obtaining a high image density and 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.

[0017]

The above object is achieved by
This can be achieved by the present invention described below.

That is, according to the present invention, the average pore radius is from 20 to
In the range of 200 ° and the half width of the pore size distribution is 20 to 1
A recording medium characterized by containing alumina hydrate in the range of 50 °.

The present invention also relates to a recording medium in which an ink receiving layer containing a pigment and a binder is provided on a base material, wherein the pigment is alumina hydrate and the ink receiving layer has an average pore radius of 20 to 200 ° . in the range, as a recording medium in which the half-width of the pore size distribution is characterized in that in the range of 20～150A.

Further, the present invention provides a method for producing a fibrous substance , wherein an alumina hydrate having an average pore radius in the range of 20 to 200 ° and a half width of the pore diameter distribution in the range of 20 to 150 ° is internally added. It is a recording medium characterized by the following.

Further, the present invention provides a composition containing 0.1 to 1.0% by weight of nitrate and having an average pore radius of 20 to 200 ° .
In Yes, the alumina hydrate half width of pore diameter distribution is <br/> the range of 20~150Å dispersed at a solids concentration of 15 wt% in deionized water, viscosity, temperature 20 ° C., shear rate 7 .9 seconds
-75 CPS or less as measured by ^-1 ;
1 to 1.0% by weight and an average pore radius of 20 to 2
And the half width of the pore size distribution is 20 to 15
Alumina hydrate in the range of 0 ° is dispersed in ion-exchanged water at a solid content of 20% by weight, and has a viscosity of 100 PS or less as measured at a temperature of 20 ° C. and a shear rate of 10.2 sec− ¹ , or the nitrate containing 0.1 to 1.0 wt%, and the range the average pore radius is 20～200A, ion-exchange hydrated alumina half width of pore size distribution in the range of 20~150Å Dispersed in water at a solid concentration of 25% by weight,
A dispersion of alumina hydrate, having a viscosity of 500 PS or less as measured at a temperature of 20 ° C. and a shear rate of 10.2 sec ⁻¹ .

The dispersion of these alumina hydrates is used as an internal additive during the production of the recording medium, specifically, as an internal additive during the production of a medium such as paper (for example, when the raw material is prepared in the papermaking process, the pulp slurry is added to the dispersion). Added) or as a coating liquid for forming an ink receiving layer on a substrate.

Furthermore, the present invention relates to an ink jet recording method in which a small droplet of ink is ejected from a fine hole and applied to a recording medium to perform printing, wherein the recording medium is used. is there.

By using the recording medium of the present invention, even if inks of various compositions having different types and amounts of dyes and solvents are used, good printing can be performed with the same quality without affecting or changing the recorded image. There is an advantage that you can.

The recording medium of the present invention is a recording medium containing, as an essential component, alumina hydrate having at least the average pore radius and the half width of the pore diameter distribution within the above-mentioned specific ranges, For example, a structure in which alumina hydrate is internally added to a sheet of paper from the stage of preparing the raw material of the sheet, or as shown in FIG. The ink receiving layer is formed as a single layer. Alumina hydrate has a positive charge, so the ink dye can be fixed well and a good color image can be obtained, and the browning and lightfastness of the black ink, which have conventionally been caused by using a silica compound, can be obtained. In particular, it is most preferable as a material used 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.

A general alumina hydrate can be produced by a known method such as hydrolysis of aluminum alkoxide and hydrolysis of sodium aluminate. Rose
k et al. (Collect Czech Chem Com
Mun, 56, 1253-1262, 1991) report that the porous structure of alumina hydrate is affected by deposition temperature, solution pH, aging time, and surfactant.

The shape of the alumina hydrate used in the present invention is as follows.
Preferably, it is a flat plate and has 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 a 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 of the flat surface is the ratio of the minimum value diameter to the maximum value diameter of the flat surface by observing the particles with a microscope similarly to 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 may be 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., Appli.
ed Catalysis, Vol. 74, 29-36, 19
It is generally known that there are cilia-like and non-ciliform shapes as described in (1991).

According to the findings of the present inventors, among alumina hydrates, a plate-like shape has better dispersibility than a hairy bundle (ciliform). Since the orientation of the alumina hydrate particles is random as shown in the photograph as a substitute for a drawing, 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.

The BET specific surface area of the alumina hydrate, the pore diameter distribution, the pore volume, and the isothermal nitrogen adsorption / desorption curve of the alumina hydrate and the ink receiving layer containing the alumina hydrate are as follows:
It can be determined simultaneously by the nitrogen adsorption and desorption method.
The BET specific surface area of the alumina hydrate used in the present invention is 70
The range is preferably from 300 m ² / g 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 shifted to the larger side and the dye in the ink cannot be sufficiently adsorbed and fixed. May not be applied with good dispersibility and the pore size distribution may not 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 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 higher than 8, the alumina hydrate finally obtained 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 size grow, the gaps between the primary particles forming the pores become uniform, and the pore size 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 grow,
In particular, it is considered that the size of the gap between the primary particles forming the pores is also uneven, and as a result, the pore size distribution is widened. The correlation between the degree of non-uniformity of the primary particles and the width of the pore size distribution is not clear. The sol obtained here can be used as it is as a dispersion as disclosed in JP-A-2-276670, but in the present invention,
It is preferable that the sol is dried once by a method such as spray drying to obtain a powder, and then a dispersion is obtained. In this case, the dispersibility of the alumina hydrate in water is further improved.

In the above-described embodiment of the recording medium of the present invention, a coating liquid (dispersion of alumina hydrate) in which the above-mentioned alumina hydrate as a pigment and a binder are applied onto a substrate is applied. An ink receiving layer.

Here, the alumina hydrate as described above has a wide half-value width of the pore size distribution as described later, and is dispersed up to the primary particles in the coating dispersion. Even if the ink receiving layer is formed through the steps of dispersion, coating on a substrate, and drying, a substantially wide pore size distribution is maintained. Although the reason for this is not clear, 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. The object particles are oriented in random directions in the ink receiving layer, or a wide pore size distribution due to the non-uniform particle size of alumina hydrate is maintained in the ink receiving layer. It is guessed.

The physical properties of the ink receiving layer are not determined only by the alumina hydrate used, but also by the type and amount of the binder, the concentration, the viscosity, the dispersion state of the coating liquid, the coating device,
In the present invention, the production conditions are controlled to an optimum range in order to obtain the characteristics of the ink receiving layer, since the production head varies depending on various production conditions such as a coating head, a coating amount, an amount of drying air, a temperature, and a blowing direction. There is a need.

The average pore radius of the ink receiving layer is from 20 to
At 200 °, the half width of the pore size distribution is preferably from 20 to 150 °, more preferably from 80 to 150 °. Here, the half width of the pore diameter distribution indicates the width of the pore radius which is half the frequency of the average pore radius. When the average pore radius is larger than the 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 than the lower limit, the ink absorption is deteriorated. Beading is likely to occur. If the half width is outside the above range, the absorption of the dye or the solvent component in the ink will be poor.

Similarly to the ink receiving layer, the pore diameter distribution of the alumina hydrate constituting the ink receiving layer has an average pore radius of 20 to 200 ° and a half width of the pore diameter distribution of 20 to 150 °.
Å is preferred. Since the pore size distribution of the ink receiving layer depends on the pore size distribution of the alumina hydrate, if it is outside the above range, the pore size distribution of the ink receiving layer cannot be within the above specified range.

The pore volume of the ink receiving layer is 0.4 to 0.6.
A range of cc / g is preferred. When the pore volume of the ink receiving layer is larger than the above range, the ink receiving layer is cracked and powder falls off. When the pore volume is smaller than the above range, the ink absorption becomes poor. Further, the pore volume of the ink receiving layer is 8 cc /
It is preferably at least m ² . Below this range, particularly when multicolor printing is performed, the ink tends to overflow from the ink receiving layer and bleed into the image. The pore volume of the alumina hydrate constituting the ink receiving layer is preferably in the range of 0.4 to 0.6 cc / g as in the ink receiving layer. Outside this range, the pore volume of the ink receiving layer cannot be set in the above-mentioned specified 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, obtained 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. If it exceeds the above range, drying of the ink after printing becomes poor.

Japanese Patent 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, and the shape of the ink bottle is narrow. It is described that a gourd shape or a meandering shape in which the middle part is constricted is 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.

In the recording medium of the present invention, the number of hydroxyl groups on the surface of the alumina hydrate 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 on the surface of the alumina hydrate can be determined by titration of a triethylaluminum solution.

The surface potential of the 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 value of the zeta potential is
Direct comparison of absolute values unless measurement is performed by unifying measurement conditions and equipment because it depends on the cell, electrode structure, applied voltage, solid content concentration, pH of the dispersion, dispersant and additives used in the measurement device Can not.

The alumina hydrate used in the present invention preferably has 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. 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. Alumina hydrate is generally stable in a low pH region, and it is known that an acid is added to lower the pH of a dispersion to improve dispersibility. It is not preferable in that a pungent odor or corrosion is generated and the type of binder used is restricted. In addition, 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 range is increased, depending on the type of alumina hydrate, the primary particles are aggregated to increase the particle diameter, and 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 the dispersed particles. As a method for measuring the particle diameter, a known method can be adopted. However, the particle diameter in the pH 6 dispersion at which the zeta potential is measured is p
It is necessary to confirm that the particle diameter is almost the same as the particle diameter in the H4 dispersion liquid.

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 hydrate of alumina 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 hydrated alumina 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 according to the present invention 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.

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 inventor has found that by widening the pore size distribution as described in the present specification, the print quality does not change even when the ratio of the dye to the solvent or the material composition of the ink changes. .

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) In the above conventional example, a hair bundle-like pseudo-boehmite sol and a method for producing an ink receiving layer using the same are described. It also describes the shape of pseudo-boehmite and the solids concentration of the dispersion. In contrast, the inventor
It has been found that a "flat" amorphous alumina hydrate is used.

Since such a plate-like amorphous alumina hydrate is produced by hydrolyzing a long-chain aluminum alkoxide as described above, an alumina hydrate with little contamination of ions or raw material alcohols can be easily prepared. It is possible to get. In this hydrolysis, it is easy to control the shape for making the alumina hydrate particles flat. In addition, the plate-like amorphous alumina hydrate has a higher dispersibility than known alumina hydrates in a hairy bundle. Further, the dispersion is not directly prepared from the sol state, but the obtained alumina hydrate is once dried and pulverized and used to easily prepare a dispersion having a high solid content and a low concentration. be able to.

In the recording medium of the present invention, the binder that can be used in combination with the alumina hydrate can be freely selected from water-soluble polymers. For example, polyvinyl alcohol or a modified product thereof (cation-modified, anion-modified, or silanol-modified), 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 , Cellulose derivatives such as hydroxypropyl methylcellulose, SBR latex, NBR latex, conjugated diene copolymer latex such as methyl methacrylate-butadiene copolymer, functional group modified polymer latex, and vinyl copolymer such as ethylene vinyl acetate copolymer. Preferred are a polymer latex, polyvinylpyrrolidone, maleic anhydride or a copolymer thereof, and an acrylate copolymer. 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 the range of 1: 1 to 30: 1, more preferably 5: 1 to 25: 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.

The alumina hydrate and the binder may contain, if necessary, an alumina hydrate dispersant, a thickener, a pH adjuster, a lubricant, a fluidity modifier, a surfactant, an antifoaming agent, a waterproofing agent,
It is also possible to add a foam inhibitor, a releasing 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 as needed.

As the water-proofing agent, any known materials such as halogenated quaternary ammonium salts and quaternary ammonium salt polymers can be freely selected and used.

As the base material of the recording medium of the present invention, papers such as appropriately sized paper, non-size paper, resin-coated paper using polyethylene and the like, sheet materials such as thermoplastic films, A fabric can be used, and there is no particular limitation. For thermoplastic films, polyester, polystyrene, polyvinyl chloride, polymethyl methacrylate,
A transparent film of cellulose acetate, polyethylene, polycarbonate, or the like, or an opaque sheet formed by filling or fine foaming with alumina hydrate can also be used.

A 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. As a coating method, a coating technique using a commonly used blade coater, air knife coater, roll coater brush coater, curtain coater, bar coater, gravure coater, 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.
² If necessary, the surface smoothness of the ink receiving layer can be improved by using a calender roll or the like after coating.

The recording medium of the type in which the alumina hydrate according to the present invention is internally incorporated is 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 an internal addition method, a paper strength improver, a retention improver, and a colorant can be added as necessary. 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.

On the other hand, 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 coloring material, for example, a direct dye, an acid dye, a basic dye, a reactive dye, and a water-soluble dye represented by an edible dye are preferable,
Any combination can be used as long as it provides an image that satisfies the required performance, such as fixability, color development, clarity, stability, light resistance, and the like, in combination with the above-described recording medium.

The water-soluble dye is generally used by dissolving 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 the water content in the ink is 20 to 90% by weight, more preferably 60 to 9% by weight.
It is preferable to adjust so as to be within the range of 0% 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-hexanetrio
Alkylene glycols having an alkylene group of 2 to 6 carbon atoms such as thiodiglycol, hexylene glycol, diethylene glycol, glycerin, ethylene glycol methyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, triethylene glycol monomethyl ether, And lower alkyl ethers of polyhydric alcohols such as triethylene glycol monoethyl ether. Among 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 preferable. Polyhydric alcohols are particularly preferable because they have a large effect as a lubricant for preventing the nozzles from being reduced in 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 adjustor and a specific resistance adjuster can be used.

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

[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 Size Distribution, Pore Volume, Isothermal Desorption Curve Characteristics A recording medium having a receptor layer formed on an alumina hydrate or PET film is heated and degassed sufficiently, and nitrogen It measured using the adsorption-desorption method. (Autosorb 1 manufactured by Cantachrome Co., Ltd.)-The BET specific surface area was calculated by the method of Brunauer et al. (J. Am. Chem. Soc., 60, 3
09, 1938)-The calculation of the pore (half) diameter and the pore volume used the method of Barrett et al. (J. Am. Chem. Soc., 73
Volume, 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 The X-ray diffraction 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 became 0.1% by weight, and the dispersion was adjusted to pH 6 with nitric acid and measured. . (Bi-ZETA plus, Brookhaven, liquid temperature 20 ° C, using acrylic cell)

6) Solution Viscosity An aqueous dispersion having a solid content concentration of alumina hydrate of 15% by weight, 20% by weight or 25% by weight was prepared, and at a temperature of 20 ° C., VISCOMTER manufactured by TOKIMEC was used. The measurement was performed at a shear rate of 7.9 sec ^-1 (when the solid content concentration was 15% by weight) or at a shear rate of 10.9 sec ^-1 (when the solid content concentration was 20 or 25% by weight).

7) Nitrate The nitrate was extracted from alumina hydrate with hot water, measured by ion chromatography (Hitachi, L-3720), and quantified as the weight% in dry 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 provided with 128 nozzles at a nozzle interval of 16 nozzles per 1 mm, ink of 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 Properties Y, M, C, Bk
After solid printing of each ink in single color or multicolor, the drying state of the ink on the surface of the recording medium was examined by touching the recording portion with a finger. The ink amount in monochromatic printing was set to 100%. When the ink amount was 200% and the ink did not adhere to the finger, it was evaluated as ％, when the ink amount was 100% and the ink did not adhere to the finger, and was evaluated as Δ.

(2) Image Density Y, M, C, Bk
The image density of each of the solid printed images was evaluated using a Macbeth reflection densitometer RD-918.

(3) Bleeding and beading For the following ink composition 1, the bleeding 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 was evaluated. Further, for each of the following two types of ink compositions, beading after solid printing of each of Y, M, C, and Bk inks in a single color or in multiple colors was visually evaluated. The ink amount in monochromatic printing was set to 100%. If 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 1 Dye 5 parts Diethylene glycol 10 parts Polyethylene glycol 10 parts Water 75 parts

Ink composition 2 Dye 5 parts Glycerin 15 parts Polyethylene glycol 20 parts Water 70 parts

Ink dye Y: C.I. I. Direct Yellow 86 M: C.I. I. Acid Red 35 C: C.I. I. Direct Blue 199 Bk: C.I. I. Food black 2

Examples 1 to 4 Aluminum dodecoxide was prepared by the method described in US Pat. No. 4,242,271. Next, the aluminum dodexide was hydrolyzed by the method described in U.S. Pat. No. 4,202,870 to produce an alumina slurry. Water was added to the alumina slurry until the alumina hydrate solid content became 7.9%. Alumina slurry p
H was 9.5. Add 3.9% nitric acid solution and adjust pH
Was adjusted. A colloidal sol was obtained under each aging condition shown in Table 1. The 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. Further, as shown in a drawing substitute photograph (electron microscope photograph: magnification of 60,000 times) 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 (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. The above four types of alumina hydrates are dispersed in ion-exchanged water in the same
A 5% by weight dispersion was obtained. The alumina hydrate and the polyvinyl alcohol solution were weighed, mixed and stirred in such a manner that the solid content of the alumina hydrate and the solid content of the polyvinyl alcohol became 10: 1 in weight mixing ratio to obtain a mixed dispersion. The above mixed dispersion was die-coated on a PET film having a thickness of 100 μm (Lumirror, manufactured by Toray Industries, Inc.) and a thickness of 30 μm was obtained.
Was obtained. FIG. 4 is a drawing substitute photograph (electron micrograph: magnification of 50,000 times) showing a cross section of the ink receiving layer, and shows that the plate-like 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 mixed with the alumina hydrate solids and the same polyvinyl alcohol solids as in Example 1 by weight. An amount of 15: 1 was measured, mixed and stirred to obtain a mixed dispersion. The mixed dispersion quality paper (Daishowa Paper Co., Shiraoi 157) to obtain an ink-receiving layer was 20 g / m ² air-knife coating on. 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) 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 solid content of pulp, and 0.05% by weight of a polyacrylamide-based retention improver (Pearl Floc 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 sheet former. Next, 2% oxidized starch (Made by Nippon Shokuhin Co., Ltd., M
S3800) 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)
7) was applied on the same PET film as in Example 1 to prepare a recording medium. 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 produce 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.

[0092]

[Table 1]

[0093]

[Table 2]

[0094]

[Table 3]

[0095]

[Table 4]

[0096]

[Table 5]

[0097]

[Table 6]

[0098]

The recording medium of the present invention and the ink jet recording method using the same have the following effects. 1) Since each ink dye and the solvent component are selectively adsorbed to pores having a specific diameter, using a medium having a wide pore diameter distribution makes it less likely to be affected by the ink composition. Therefore, the selectivity to the ink composition is increased. 2) By having no hysteresis, the solvent component in the ink is easily desorbed, the drying property of the ink is improved, and bleeding is prevented, and show-through can be prevented. 3) When a plate-shaped alumina is used, the gap between the particles can be widened when the close-packed structure is adopted, so that a medium having a pore size having a somewhat wide distribution can be obtained. 4) Since the dispersibility is good, the viscosity can be reduced even in a dispersion having a high solid content. 5) Since the dispersibility is good even in a neutral pH range, the amount of acid added to the dispersion can be reduced.

[Brief description of the drawings]

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

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

FIG. 3 is a photograph substituted for a drawing showing the shape of the alumina hydrate of the present invention.

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

FIG. 5: Isothermal adsorption of alumina hydrate of Example 1 of the present invention
It is a figure showing a curve .

FIG. 6 shows the pore size distribution of alumina hydrate of Example 1 of the present invention.
It is a figure showing a cloth .

[Explanation of symbols]

 1 base material 2 ink receiving layer

Claims (28)

(57) [Claims] 1. The average pore radius is in the range of 20 to 200 ° .
There, the recording medium which the half-width of the pore size distribution characterized in that it comprises an alumina hydrate Oh <br/> Ru in the range of 20～150A. 2. A recording medium the ink receiving layer provided on a substrate comprising a pigment and a binder, the pigment is alumina hydrate, and 20 an average pore radius of the ink receiving layer
In the range of 200 ° and the half width of the pore size distribution is 20 to 1
A recording medium characterized by being in the range of 50 °. 3. The fibrous substance has an average pore radius of 20 to 2
And the half width of the pore size distribution is 20 to 15
A recording medium characterized by internally adding an alumina hydrate in the range of 0 °. 4. The alumina hydrate having a pore volume of 0.4 to 0.4.
4. The recording medium according to claim 1, wherein the recording medium is in a range of 0.6 cc / g. 5. The ink receiving layer having a pore volume of 0.4 to 0.4.
The recording medium according to claim 2, wherein the recording medium is in a range of 0.6 cc / g. 6. The ink receiving layer having a pore volume of 8 cc / cm.
^{3. The} recording medium according to claim 2, wherein the recording medium is at least m ² . 7. 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 any one of claims 1 , 3 and 4 . 8. 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. A recording medium according to any one of claims 2, 5, and 6. 9. The recording medium according to claim 1, wherein said alumina hydrate is an amorphous compound. 10. The recording medium according to claim 9, wherein the alumina hydrate is a tabular alumina hydrate having an average aspect ratio of 3 to 10. 11. The BET specific surface area of the hydrated alumina plate is in the range of 70 to 300 m ² / g.
A recording medium according to claim 1. 12. The recording medium according to claim 10, wherein the average aspect ratio of the flat surface of the flat alumina hydrate is in the range of 0.6 to 1.0. 13. The alumina hydrate having 10 hydroxyl groups.
^The recording medium according to any one of claims 1 to 4, 7, and 9, wherein the number is ²⁰ pieces / g or more. 14. The recording medium according to claim 1, wherein the zeta potential of the alumina hydrate at pH 6 is 15 mV or more. 15. The ratio of 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. 16. 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. 17. The alumina hydrate is represented by the following formula:
A recording medium according to any one of claims 1 to 16. Al ₂ O _3-n (OH) _2n · mH ₂ O (where n represents an integer of 0 to 3, and m represents a value of 0 to 10)
Represent) 18. The method according to claim 1, which is for inkjet recording.
18. The recording medium according to any one of claims 17 to 17. 19. It contains 0.1 to 1.0% by weight of nitrate and has an average pore radius in the range of 20 to 200 °,
When the half-width of the pore size distribution are dispersed at a solids concentration of 15 wt% of the alumina hydrate to deionized water in the range of 20～150A, viscosity, temperature 20 ° C., shear rate 7.9 s ^-1 A dispersion of alumina hydrate, characterized in that the dispersion is 75 CPS or less as measured by (1). 20. The nitrate containing 0.1 to 1.0 wt%, and an average pore radius is in the range of 20～200A,
When the half-width of the pore size distribution are dispersed at a solids concentration of 20 wt% in deionized water an alumina hydrate in the range of 20～150A, viscosity, temperature 20 ° C., shear rate 10.2 s ^-1
A dispersion of alumina hydrate, characterized in that the dispersion is 100 CPS or less as measured by the method described in (1). 21. A composition containing 0.1 to 1.0% by weight of nitrate and having an average pore radius in a range of 20 to 200 °,
When the half-width of the pore size distribution are dispersed at a solids concentration of 25 wt% in deionized water an alumina hydrate in the range of 20～150A, viscosity, temperature 20 ° C., shear rate 10.2 s ^-1
A dispersion of alumina hydrate, characterized in that the dispersion is not more than 500 CPS as measured by the method described in (1). 22. The dispersion according to claim 19 , wherein the dispersion is a dispersion of a pigment for producing a recording medium. 23. Discharge a small droplet of ink from a fine hole,
In the ink jet recording method for printing by applying to a recording medium, ink jet recording method which comprises using a recording medium according to any one of claims 1 to 18. 24. The ink jet recording method according to claim 23 , wherein thermal energy is applied to the ink to eject the ink droplet. 25. Claims 1 to 18 printed matter on which an image is formed on a recording medium according to any one of. 26. The average pore radius is in the range of 20 to 200 °.
And the half width of the pore size distribution is in the range of 20 to 150 °.
Applying a dispersion containing alumina hydrate on a substrate
Or added to slurry containing fibrous material
A method for manufacturing a recording medium, which is performed by paper. 27. 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 26, wherein the method is applied. 28. A dispersion comprising the alumina hydrate
5-45 g / m in terms of dry solids on the material ^Two Range of application
A method for manufacturing a recording medium according to claim 26.