JP2000071609A - Recording medium, image forming method using this recording medium, manufacture of this recording medium, alumina dispersion and preparation of alumina dispersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording medium giving a large freedom of selection of ink, causing little migration and bleeding in addition, having a high optical density in the printed part and being excellent in glossiness and transparency and in the reproducibility of halftone in particular, an image forming method using this medium, a manufacturing method for the medium and, moreover, an alumina dispersion excellent in dispersion stability and a preparing method for this alumina dispersion. SOLUTION: In a recording medium constituted by forming an ink receiving layer on a base, an alumina hydrate having a boehmite structure and a zirconium compound of non-coupling properties are contained in the ink receiving layer. As for an image forming method, ink is discharged onto this recording medium from fine pores. An alumina dispersion contains the alumina hydrate, a binder, an inorganic salt of zirconium and/or an organic salt thereof.

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 ink-jet recording, particularly suitable for outputting a photo image, a method for producing the same, an image forming method using the same, an alumina dispersion, and an aqueous alumina dispersion. It relates to a manufacturing method.

[0002]

2. Description of the Related Art In recent years, an ink jet recording system records fine images of ink and characters by causing fine droplets of ink to fly according to various operating principles and adhere to a recording medium such as paper. It has features such as high speed, low noise, easy multi-coloring, great flexibility of recording patterns, and no need for development and fixing. It is rapidly spreading in various applications such as information equipment as a recording device for various images. 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.

In the ink jet recording system, recording apparatuses and recording methods have been improved with improvements in recording characteristics such as higher recording speed, higher definition, and full color printing. Characteristics have been required. In order to solve such a problem, various types of recording media have been conventionally proposed. For example, Japanese Patent Application Laid-Open No. 55-5830 discloses an ink jet recording sheet provided with an ink-absorbing coating layer on the surface of a support, and Japanese Patent Application Laid-Open No. 55-51583 discloses amorphous ink as a pigment in a coating layer. An example using porous silica is disclosed.

[0004] US Patent Nos. 4,879,166 and 5
104730, JP-A-2-276670, 3
JP-A-215082, JP-A-3-281383 and the present inventors have proposed a recording sheet having an ink receiving layer using alumina hydrate having a pseudo-boehmite structure.

In recent years, there have been many proposals for recording media using a zirconium compound. For example, JP-A-4-
No. 7189 discloses a method for manufacturing a recording medium provided with an ink receiving layer containing a porous pigment and a zirconium salt. Also, JP-A-5-85033,
JP-A-5034 and JP-A-5-85035 propose recording media in which an intermediate layer is provided between various ink-receiving layers and a substrate, and discloses an example in which a zirconium-based crosslinking agent is used in the intermediate layer. ing. JP-A-6-32046 proposes a recording medium having an ink receiving layer containing a specific amount of a non-quality silica, a vinyl alcohol copolymer having a silanol group, and a zirconium compound. US Patent 473
No. 2,786 discloses a recording medium having an ink-receiving layer containing a specific amount of a pigment, a binder, an insolubilized hydrophilic polymer, and a zirconium compound as a polyvalent cation.

However, although the strength of the coating film is improved in the above-described recording medium, it has not been possible to achieve sufficient ink absorbency, resolution, and gradation to express an image comparable to a silver halide photograph. , Water resistance and image storability were not satisfactory.

Japanese Patent Application Laid-Open No. 9-76628 discloses a recording medium having an ink receiving layer containing alumina hydrate which has been surface-treated with a zirconium-based coupling agent. However, further improvement in performance has been desired for use in a recent photo inkjet printer which has been able to output a high-quality image comparable to a silver halide photograph even on the above-described recording medium.

[0008] In order to form a smooth gradation which is important in outputting a photo image, a photo ink-jet printer expresses a density gradation by overlapping inks of low density or different density. for that reason,
The amount of ink applied per unit area is significantly larger than that of conventional inkjet printers.
On the other hand, a large amount of surfactant is contained in the ink medium or a highly hydrophilic dye is used in order to enhance the permeability of the ink so that it can be output to plain paper. For this reason, even when alumina hydrate having high dyeing properties is used, there is a case where the ink easily bleeds and the resolution of the image is reduced in a place where the amount of the applied ink is large, or the dye may cause migration after recording. .

On the other hand, as a method for producing an alumina hydrate dispersion, various methods have conventionally been known. For example,
JP-A Nos. 54-116398 and 55-23034.
JP-A-55-27824 and the like, a gel of alumina hydrate is formed by a reaction between a basic aluminum salt and an acid or an alkali, or a reaction between an acidic aluminum salt and an alkali, A method for producing an alumina hydrate dispersion by peptizing with an acid is disclosed.
A method of producing an alumina hydrate by hydrolyzing an aluminum alkoxide to form an alumina hydrate and pulverizing with an acid to obtain an alumina hydrate dispersion, JP-A-57-88074;
JP, JP-A-62-56321, JP-A-4-275
No. 917, No. 6-64918, No. 7-105
No. 35, 7-267633, U.S. Pat. No. 2,656,321, Am. Ceramic S
oc. Bull. , 54, 289 (1975).

However, in order to obtain an alumina hydrate dispersion using a deflocculant such as an acid, Japanese Patent Application Laid-Open No. 62-56
As described in US Pat. No. 321, it is necessary to add a large amount of peptizer. If the amount of the deflocculant used is small, the time required for deflocculation becomes longer or deflocculation becomes insufficient. JP-A-7-10535 discloses a method of peptizing under high temperature and pressure in order to reduce the amount of peptizer used and to shorten the time required for peptization. Peptization under pressure requires a pressure reactor. Also, the use of acid at high temperature and under pressure shortens the life of the reaction vessel,
There are many manufacturing restrictions.

Japanese Patent Application Laid-Open No. 6-064919 discloses that
A method is disclosed in which an acid is added to alumina hydrate to produce a sol by ultrasonic treatment.However, special equipment is required and the production restrictions are large. Is difficult and the pot life may be shortened.

Also, as described in Japanese Patent Application Laid-Open No. 7-10535, when the amount of acid used for peptization is large, gelation occurs when the solid content concentration is increased. It was extremely difficult to increase the concentration of the liquid dispersion.

A high-concentration, low-viscosity alumina sol to which a water-soluble aliphatic amino acid or a lactam which is a derivative thereof is added (see Japanese Patent Application Laid-Open No. 61-283335); 1-171
633) and those in which the content of cations other than hydrogen ions is specified (see JP-A-8-295509). However, even with these methods,
The formation of coatings, paints, ceramic bulk bodies,
When a water-soluble or water-dispersible polymer is mixed to give a binding property or a shape-imparting property for the purpose of forming a dissolving carrier, dispersion stability is deteriorated, and sufficient viscosity reduction and pot life cannot be obtained.

[0014]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a wide selection range of inks, less migration and bleeding, a high optical density in a printing portion, good transparency, and especially, a photo image output. And to provide a recording medium having excellent halftone reproducibility and an image forming method using the same.

A further object of the present invention is to provide a method for easily producing a recording medium which is excellent in the dispersion stability of a coating solution, has a high pH and is free from problems such as corrosion, and does not require any special production equipment. It is in.

Further, an object of the present invention is to have excellent binding properties and shape imparting properties, and have a low viscosity at a high solids concentration,
Further, the present invention provides an alumina dispersion having excellent dispersion stability and a long pot life.

Another object of the present invention is to provide a production method which can easily produce an alumina dispersion having such properties without requiring special production equipment.

[0018]

The above objects are achieved by the present invention described below.

That is, the present invention relates to a recording medium comprising an ink receiving layer formed on a substrate, wherein the ink receiving layer comprises an alumina hydrate having a boehmite structure and a non-coupling zirconium compound. Is a recording medium characterized by containing:

Further, the present invention relates to a method for producing a recording medium having an ink receiving layer formed on a substrate, comprising a dispersion containing alumina hydrate having a boehmite structure, a non-coupling zirconium compound and a binder. A method for producing a recording medium, characterized in that a liquid is applied on a substrate and dried to form an ink receiving layer.

Further, the present invention provides an image forming method in which ink is ejected from a fine hole and applied to a recording medium to perform printing, wherein the recording medium described above is used as the recording medium. Is the way.

Further, the present invention is an alumina dispersion comprising an alumina hydrate, a binder, and an inorganic and / or organic acid salt of zirconium.

The present invention is also a process for producing an alumina dispersion, which comprises mixing and dispersing a binder in a dispersion containing alumina hydrate and an inorganic and / or organic salt of zirconium.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The recording medium of the present invention is an ink receiving medium formed of an alumina hydrate mainly showing a boehmite structure on a substrate, a non-coupling zirconium compound, and preferably a binder. This is a configuration in which a layer is formed.

Alumina hydrate has a positive charge, so that the dye in the ink is fixed well, and an image having excellent color developability can be obtained. Further, there are no problems such as browning of the black ink and light fastness. Therefore, it is preferable as a material used for the ink receiving layer.

As the alumina hydrate present in the recording medium of the present invention, an alumina hydrate having a boehmite structure by an X-ray diffraction method is most preferred because it has good dye adsorbing properties, ink absorbing properties and transparency. preferable.

Alumina hydrate is defined by the following general formula:

Al ₂ O _3-n (OH) _2n · mH ₂ O In the formula, n represents one of integers from 0 to 3, and m represents 0 to 1
It shows a value of 0, preferably 0 to 5. m and n do not become 0 at the same time. The expression mH ₂ O often refers to a detachable aqueous phase which does not participate in the formation of a crystal lattice, and can therefore take on m or a non-integer value.

The method for producing the alumina hydrate having a boehmite structure contained in the recording medium in the present invention is not particularly limited, but a method capable of producing the alumina hydrate, for example, the Bayer method, the light-emitting method, and the like. Any method such as a dust pyrolysis method can be adopted. Preferably, a method in which an acid is added to a long-chain aluminum alkoxide to carry out hydrolysis is used. For example, it is preferable to use an alkoxide having 5 or more carbon atoms and further use an alkoxide having 12 to 22 carbon atoms because removal of an alcohol component as described later and control of the shape of alumina hydrate having a boehmite structure are facilitated. . The above-described 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, since long-chain aluminum alkoxides easily remove alcohol after hydrolysis, it is possible to completely remove alcohol from hydrated alumina, as compared with the case of using short-chain alkoxides such as aluminum isopropoxide. There is an advantage that you can.

The alumina hydrate obtained by the above method can be further subjected to hydrothermal synthesis to grow particles.
It is also possible to obtain an alumina hydrate powder by drying.

In general, the crystal of alumina hydrate having a boehmite structure is a layered compound whose (020) plane forms a giant plane, and shows a diffraction peak specific to an X-ray diffraction pattern. As the boehmite structure, a structure containing excess water between layers on the (020) plane, called pseudo-boehmite, in addition to complete boehmite, may be employed. This pseudo boehmite X
The line diffraction pattern shows a broader diffraction peak than perfect boehmite. Since complete boehmite and pseudo-boehmite cannot be clearly distinguished from each other, unless otherwise specified in the present invention, the term "alumina hydrate showing a boehmite structure" includes both of them.

The recording medium containing the alumina hydrate having a boehmite structure according to the present invention preferably has a crystallinity in the range of 15 to 80. Within this range, the optical density of the printed portion is increased, and the occurrence of bleeding, beading, and cissing is reduced.

Here, the crystallinity of the recording medium is determined by the inventors of the present invention as disclosed in Japanese Patent Application Laid-Open No. 8-132273.
CuKα measured on a powdered recording medium
Intensity at 2θ = 10 ° C. in the X-ray diffraction diagram
It is an amount determined by the ratio of the peak intensity of the (020) plane appearing near θ = 14 to 15 °. This degree of crystallinity is a physical quantity corresponding to the ratio of the crystalline part to the amorphous part of the alumina hydrate present in the recording medium.

Similarly, the bleeding referred to in the present invention means that when solid printing is performed on a fixed area, a portion colored by a dye becomes larger (larger) than the printed area. Refers to a phenomenon in which granular density unevenness appears due to agglomeration of ink droplets generated in a portion, and cissing means that a non-colored portion occurs in a solid printing portion.

It is preferable that the parallelism between the microcrystal of alumina hydrate having a boehmite structure and the in-plane direction of the ink receiving layer is 1.5 or more. This degree of parallelism is defined in the crystallinity section in the examples described later. When the parallelism is 1.5 or more, the roundness of the printed dots is increased, which is preferable. If the parallelism is less than 1.5, the roundness of the printed dots will be low. The more preferable range is 2 or more, and the gloss of the recording medium is increased.

Among the alumina hydrates, pseudo-boehmite includes:
References (Rosek J., et al., Applie)
d Catalysts, 74, 29-36, 1
991), it is generally known that there are cilia-like and other shapes. In the present invention, cilia-shaped or flat plate-shaped alumina hydrate can be used. The shape of alumina hydrate having boehmite structure (particle shape, particle size, aspect ratio)
Alumina hydrate can be dispersed in ion-exchanged water and dropped on a collodion membrane to prepare a measurement sample, and the measurement can be performed by observing this sample with a transmission electron microscope.

According to the findings of the present invention, the flat shape has better dispersibility in water than the hairy bundle (ciliform), and the orientation of the alumina hydrate particles when the ink receiving layer is formed. Is more preferable because the pore volume is large and the pore size distribution is wide because the is random. Here, the hair bundle shape means a state in which needle-shaped alumina hydrates are gathered like a bundle of hair in contact with the side surfaces.

The aspect ratio of the flat plate is 5-1.
It can be determined by the method defined in JP-A-6015. The aspect ratio indicates the ratio of the diameter to the thickness of a particle. Here, the diameter means the diameter of a circle having an area equal to the projected area of the particles when the alumina hydrate is observed with a microscope or an electron microscope. The aspect ratio is the ratio of the diameter indicating the minimum value to the diameter indicating the maximum value of the flat surface, observed in the same manner as the aspect ratio. In the case of a hairy bundle shape, the method of determining the aspect ratio is to obtain the diameter and length of the upper and lower circles using the individual acicular particles of alumina hydrate forming the hairy bundle as a cylinder, Can be obtained by taking the ratio of the length to.

The most preferred shape of the alumina hydrate is a flat plate having an average aspect ratio of 3 to 10 and an average particle diameter of 1 to 50 nm, and a hairy bundle having an average aspect ratio of 3 to 10 nm. And the average particle length is 1
A range of ５０50 nm is preferred. When the average aspect ratio is within the above range, a gap is formed between the particles when the ink receiving layer is formed or internally added to the fibrous substance, so that a porous structure having a wide pore radius distribution can be easily formed. be able to. When the average particle diameter or the average particle length is within the above range, a porous structure having a large pore volume can be similarly produced. When the average aspect ratio is smaller than the lower limit of the above range, the pore size distribution range of the ink receiving layer becomes narrower,
When it is larger than the upper limit of the above range, it becomes difficult to produce alumina hydrate with a uniform particle size. When the average particle diameter or the average particle length is smaller than the lower limit of the above range, the pore size distribution tends to be narrow similarly, and when the average particle diameter or the average particle length is larger than the upper limit of the above range, the adsorption ability of the printed dye tends to decrease.

The pore properties of the alumina hydrate are adjusted during the production process. However, in order to obtain a recording medium that satisfies the BET specific surface area and pore volume of the ink receiving layer described later, the pore volume is controlled. Is preferably from 0.1 to 1.0 cm ³ / g. When the pore volume of the alumina hydrate is larger than the above range, the ink receiving layer is liable to cracks and powder falling, and when the pore volume is smaller than the above range, the absorption of the ink is reduced, and particularly, multicolor printing is performed. In this case, the ink overflows from the ink receiving layer, and bleeding tends to occur in the image.

The BET specific surface area is 40 to 5
It is preferable to use an alumina hydrate of 00 m ² / g. If the BET specific surface area of the alumina hydrate is smaller than this range, the glossiness of the ink receiving layer is reduced and the haze is increased, so that the image is likely to have a white haze. On the other hand, if it is larger than the above range, cracks tend to occur in the ink receiving layer.

A dispersion is prepared using the above-mentioned alumina hydrate, and an ink receiving layer can be formed on a substrate through a coating and drying process.

For the ink receiving layer of the recording medium of the present invention, a zirconium compound which does not directly bond to the above-mentioned alumina hydrate having a boehmite structure is further used. The zirconium compound exhibits a high effect of preventing adsorption and bleeding of the dye contained in the ink component in the ink receiving layer in combination with the alumina hydrate having a boehmite structure.

As described above, in recent ink jet printers, a large amount of a surfactant or a dye having a high hydrophilicity is used in order to increase the permeability to plain paper. Since such inks have a high hydrophilicity of the dye, even if the ink is substantially combined with the pigment serving as the dye adsorbent, the adsorbed dye moves together with the ink component coming later by overstrike, etc. Since the dye is easily moved by moisture and the like, bleeding, thickening of characters, migration, and the like are likely to occur. On the other hand, in the recording medium of the present invention, the zirconium compound is charged on the surface of the alumina hydrate by the combined use of a boehmite-structured alumina hydrate and a non-coupling zirconium compound which is not directly bonded to the alumina hydrate. The cationic property of the hydrate is increased, and the adsorptivity of an anionic dye mainly used in the ink jet field is improved. Therefore, the recording medium of the present invention has extremely low migration even when bleeding due to overstrike and under high temperature and high humidity. In the present invention, the non-coupling zirconium compound refers to a zirconium compound that does not chemically bond to alumina hydrate.

The above phenomenon occurs because the zirconium compound is ionized when the ink is applied and the dye is strongly adsorbed, thereby exhibiting its effect. Therefore, the zirconium compound reacts with a direct alumina hydrate such as a zirconium-based coupling agent. The ionicity of the binding compound is low. The bonding state between the alumina hydrate and the zirconium compound can be determined from the chemical shift by X-ray photoelectron spectroscopy (XPS or ESCA; hereinafter, both are referred to as ESCA).

The term "migration" as used herein refers to a phenomenon in which a dye image diffuses and moves in an ink receiving layer with the passage of time, whereby a recorded image gradually blurs and blurs.

Further, in the present invention, it has been found that the reproducibility of halftone is improved by the combined use of an alumina hydrate having a boehmite structure and a non-coupling zirconium compound. One of the important items in outputting a photo image is how to express halftones neatly. However, in the image forming method of expressing the density gradation by over-printing low density ink or different density ink which is becoming the mainstream of the recent photo ink jet printer, the hue in the shadow part where the dye density is high and the dye density are low. The hue of the low highlight part is different, and the color change is likely to occur. This is presumably because the highlight portion is expressed by thin ink, the dye concentration is extremely low, and the color change is likely to occur due to slight light scattering of the ink receiving layer. However, in the recording medium of the present invention, since the zirconium compound charges the surface of the alumina hydrate particles, the dye is easily adsorbed on the surface of the particles. For this reason, the dye does not enter the fine pores present in the alumina hydrate particles, so that light scattering is small, and the tint change in the highlight portion is extremely small, and the halftone reproducibility is excellent.

On the other hand, according to the study by the present inventors, when silica and a zirconium compound are used in combination, silica particles having physical properties sufficient to satisfy the ink receptivity have a large light scattering as described above. It was difficult to reproduce halftone.

The zirconium compound of the present invention also contributes to the dispersion stability of alumina hydrate, and plays a role as a peptizer. Thawing refers to a phenomenon in which repulsion between particles in a medium is strong and the particles are stably dispersed in the medium. In order for the particles to have a repulsive force, the particles must be charged and ions having the opposite sign to neutralize the particles must be adsorbed and have an electric double layer. This electric double layer electrostatically repels and prevents the particles from approaching. If there is no charge on the particles and no electric double layer is formed on the surface, no dissolution occurs.

Since the ziconium compound is acidic in the medium, it charges the alumina hydrate particles and forms an electric double layer on the surface of the alumina hydrate particles by the anion to promote the peptization. There is.

Such an action is not achieved by salts such as alkali metals and alkaline earth metals, and an acid such as nitric acid or hydrochloric acid, which is a general peptizer, is indispensable for peptizing alumina hydrate particles. . In general, in order to form an ink receiving layer having sufficient ink absorbency, it is important in production that the solid content of the coating liquid is high. Therefore, it is necessary to produce a high-concentration alumina hydrate dispersion, which requires a large amount of acid, and lowers the pH of the dispersion, which causes problems such as corrosion during production equipment and storage. In addition, the viscosity of the dispersion liquid tends to increase. However, when the zirconium compound of the present invention is used, even when a high-concentration alumina hydrate dispersion is produced, the pH as described above is maintained.
Is less likely to occur, and thus the viscosity of the dispersion can be reduced.

The zirconium compound used in the present invention may be any compound which does not directly bond to alumina hydrate, and among them, inorganic salts and organic acid salts are preferable. In particular,
ZrOCl ₂ .nH ₂ O, Zr ₂ O ₃ Cl ₂ , ZrCl
₄ , ZrCl ₃ , ZrCl ₂ , ZrBr ₄ , ZrBr
₃ , ZrBr ₂ , ZrI ₄ , ZrI ₃ , ZrI ₂ , Zr
Halide salts such as F ₄ , ZrF ₃ and ZrF ₂ , Zr
(NO ₃ ) ₄ .nH ₂ O, ZrO (NO ₃ ) ₂ .nH ₂
O, Zr (SO ₄ ) ₂ , Zr (SO ₄ ) ₂ .nH ₂ O,
ZrO (SO ₄ ), Zr (H ₂ PO ₄ ) ₂ , ZrP ₂ O
₇ , ZrSiO ₄ , (NH ₄ ) ZrO (CO ₃ ) ₂ , Z
rO (CO ₃ ) ₂ .nH ₂ O, ZrO (OH) ₂ .nH
₂ O oxoacid salts, zirconium acetate, zirconyl lactate, zirconyl stearate, zirconyl octylate,
Organic acid salts such as zirconyl laurate and zirconyl mandenate are exemplified, and one kind of these can be used as a mixture of two or more kinds.

The amount of the zirconium compound to be added depends on the weight ratio of the oxide of zirconia and alumina in the recording medium (Zr
O ₂ / Al ₂ O ₃ ) is from 1.0 × 10 ^{−4 to} 1.0 × 10 ⁻¹
It is preferable to select such that When the amount of the zirconium compound is too large, the color change of the dye after printing tends to increase easily due to a decrease in the pH of the coating solution. On the other hand, if the amount of the zirconium compound is too small, the adsorption of the dye is reduced, and bleeding, thickening of characters, migration and the like are likely to occur.

As a method of adding the zirconium salt, in order to effectively improve the dispersion stability of the alumina dispersion after mixing the deflocculant of the alumina hydrate particles and the binder,
It is preferable to mix a binder with a dispersion containing alumina hydrate and a zirconium salt. The zirconium salt may be added to the alumina hydrate particles and the binder successively after the zirconium salt is added in advance to the medium, or the zirconium salt and the binder may be sequentially added to the alumina sol or the alumina slurry in which the alumina hydrate particles are dispersed. Is also good. The same effect can be obtained by simultaneously adding the alumina hydrate particles and the zirconium salt to the medium.

The alumina dispersion of the present invention is prepared by using an inorganic salt and / or an organic acid salt of zirconium to obtain a solid content of 1%.
A high concentration of 0% or more can be adjusted to a relatively high pH, specifically pH =
It can be easily achieved at 3.0 or more. Thereby, even if the binder is mixed, the dispersion stability is maintained, the pot life is long, and an alumina dispersion liquid excellent in binding property and shape imparting property of alumina hydrate particles can be obtained.

The ink receiving layer of the recording medium of the present invention is preferably formed so that its total pore volume is in the range of 0.1 to 1.0 cm ³ / g. When the pore volume of the ink receiving layer is larger than the above range, the ink receiving layer is liable to crack and powder drop, and when the pore volume is smaller than the above range, the ink absorption is reduced, and multicolor printing is performed. In this case, the ink overflows from the ink receiving layer, and the image is easily blurred.

The BET specific surface area of the ink receiving layer is preferably in the range of 20 to 450 m ² / g. If it is smaller than this range, the glossiness of the ink receiving layer is reduced and the haze is increased, so that the image tends to have white haze. On the other hand, if it is larger than the above range, cracks tend to occur in the ink receiving layer.

The BET specific surface area and the pore volume are 24
After degassing at 120 ° C. for a time, it can be determined by a nitrogen adsorption / desorption method.

The pore structure and the like of the ink receiving layer are not determined by the alumina hydrate to be used, but by the kind and amount of the binder, the concentration, the viscosity, the dispersion state of the coating liquid, the coating apparatus, and the coating head. In the present invention, it is necessary to adjust the production conditions to an optimum range in order to obtain the characteristics of the ink receiving layer, since the production amount varies depending on various production conditions such as a coating amount, an amount of dry air, a temperature, a blowing direction, and the like. .

The recording medium of the present invention can be used by adding additives as necessary. As the additive, any of various metal oxides, salts of divalent or higher-valent metals, and cationic organic substances can be freely selected and used as necessary. Metal oxides include oxides such as silica, boria, silica boria, magnesia, silica magnesia, titania, zirconia, and zinc oxide, hydroxides, and salts of divalent or higher-valent metals such as calcium carbonate and barium sulfate. , Magnesium chloride, calcium bromide, calcium nitrate, calcium iodide, halide salts such as zinc chloride, zinc bromide, zinc iodide, kaolin, talc and the like. As the cationic organic substance, a quaternary ammonium salt, a polyamine, an alkylamine and the like are preferable. The additive is preferably 20% by weight or less of the alumina hydrate.

In the recording medium of the present invention, a binder can be used together with an alumina hydrate and a zirconium compound. As the binder, one type or two or more types can be freely selected and used from water-soluble and water-dispersible polymers. For example, polyvinyl alcohol or a modified product thereof, starch or a modified product thereof, gelatin or a modified product thereof, casein or a modified product thereof, gum arabic, a cellulose derivative such as carboxymethyl cellulose, polyvinylpyrrolidone, maleic anhydride or a copolymer thereof, acrylic acid Water-soluble polymers such as ester copolymers, SBR
Water-dispersible polymers such as conjugated diene-based copolymer latex such as latex, functional group-modified polymerization latex, and vinyl-based copolymer latex such as ethylene-vinyl acetate copolymer are preferred.

The mixing ratio of the alumina hydrate and the binder is as follows:
The weight ratio is preferably in the range of 1: 1 to 30: 1. Within this range, the ink absorption speed of the medium is high, and the optical density of the printing portion is high. If the amount of the binder is less than the above range, the mechanical strength of the ink receiving layer is insufficient, and cracking and powder dropout are likely to occur.If the amount of the binder is more than the above range, the pore volume is small and the ink absorption is small. The amount tends to decrease. In consideration of the ink absorptivity and the difficulty of cracking when bent, the above range is 3: 1 to 2
More preferably, it is in the range of 0: 1.

An organic acid can be preferably used for the recording medium of the present invention. Although the reason for the effect of using an organic acid in combination is not clear, it is considered that the effect is caused by the interaction with the zirconium compound when the water-soluble or water-dispersible polymer used as a binder is mixed during coating. It is to alleviate the temporary thickening phenomenon (binder shock). When an organic acid is used in combination, a coating liquid can be easily produced without the need for a disperser or a special production apparatus that requires a strong share when producing the coating liquid. In addition, there is a concern that the addition of an organic acid may cause a decrease in the pH of the coating solution and impair the dispersion stability.However, in order for the zirconium compound to act as a buffer for the organic acid, the pH is so low that the dispersion stability is impaired. It does not drop significantly. Therefore, the dispersion stability of the coating liquid was rather improved and the pot life tended to be prolonged by the combined use of the organic acid. Further, there is an effect that curl of the recording medium immediately after printing is reduced. This not only improves the texture of the printed matter, but also suppresses the occurrence of head rubbing and jamming during printing.

The organic acid suitably used in the present invention is not particularly limited, and for example, carboxylic acid, sulfonic acid, amino acid and the like are used. Specifically, as the carboxylic acid, formic acid, acetic acid, chloroacetic acid, dichloroacetic acid, trichloroacetic acid, fluoroacetic acid, trimethylacetic acid, methoxyacetic acid,
Mercaptoacetic acid, glycolic acid, acrylic acid, methacrylic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, Cyclohexanecarboxylic acid, phenylacetic acid,
Benzoic acid, o-toluic acid, m-toluic acid, p-toluic acid, o-chlorobenzoic acid, m-chlorobenzoic acid, p
-Chlorobenzoic acid, o-bromobenzoic acid, m-bromobenzoic acid, p-bromobenzoic acid, o-nitrobenzoic acid, m
-Nitrobenzoic acid, p-nitrobenzoic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, tartaric acid,
Maleic acid, fumaric acid, citric acid, phthalic acid, isophthalic acid, terephthalic acid, salicylic acid, p-hydroxybenzoic acid, anthranilic acid, m-aminobenzoic acid, p-aminobenzoic acid, o-methoxybenzoic acid, m-methoxy Benzoic acid, p-methoxybenzoic acid and the like.

As the sulfonic acid, benzenesulfonic acid,
Methylbenzenesulfonic acid, ethylbenzenesulfonic acid, dodecylbenzenesulfonic acid, 2,4,6-trimethylbenzenesulfonic acid, 2,4-dimethylbenzenesulfonic acid, 5-sulfosalicylic acid, 1-sulfonaphthalene, 2-sulfonaphthalene, hexane Amino acids such as sulfonic acid, octanesulfonic acid, dodecanesulfonic acid and the like include glycine, alanine, valine, α-aminobutyric acid,
γ-aminobutyric acid, β-alanine, taurine, serine, ε
-Amino-n-caproic acid, leucine, norleucine,
Phenylalanine is listed, and these can be used alone or in combination of two or more.

The content of the organic acid is 5.0 × 10 ^-4 mol / g to 1.0 mol / g in terms of the number of moles based on the weight of the zirconium compound in terms of oxide.
Is preferable. When the addition amount of the organic acid is too large, the buffering effect of the zirconium compound is reduced, and the pH is easily lowered, which may impair the dispersion stability.
On the other hand, if the amount of the organic acid is too small, binder shock is likely to occur when the binder is mixed with the coating solution. Also, there was no effect on the reduction of curl after printing.

In the present invention, in addition to the alumina hydrate, the zirconium compound and the binder, if necessary, a pigment dispersant, a thickener, a pH adjuster, a lubricant, a fluidity modifier, a surfactant, a defoamer Agent, waterproofing agent, foam inhibitor, release agent, foaming agent,
It is also possible to add a penetrant, a coloring dye, a fluorescent whitening agent, an ultraviolet absorber, an antioxidant, a preservative, and an indicator. Halogenated quaternary ammonium salts, quaternary
Any known material such as a quaternary ammonium salt polymer can be freely selected and used.

The base material used for forming the ink receiving layer in the present invention includes papers such as appropriately sized paper, non-size paper, range coated paper using polyethylene and the like, and thermoplastic films. Any suitable sheet-like substance can be used, and there is no particular limitation. In the case of a thermoplastic film, a transparent film of polyester, polystyrene, polyvinyl chloride, pormethyl methacrylate, cellulose acetate, polyethylene, polycarbonate, or the like, or an opaque sheet by filling with a pigment or fine foaming can be used.

The method for producing the recording medium of the present invention is not particularly limited, and a commonly used method of coating or internally adding alumina hydrate can be used. Alumina hydrate is dispersed in water and coated on a substrate or internally added to a fibrous substance. If necessary, a heating step as described in JP-A-9-86035 can be added.

The dispersion treatment of the dispersion containing the alumina hydrate having a boehmite structure, a zirconium compound and a binder can be selected from the methods generally used for dispersion. As a specific method / apparatus, a grinding-type disperser such as a ball mill or a sand mill, or a stirring disperser such as a homomixer or a homodisper is suitably used.

In the present invention, as a method of applying a coating liquid for forming an ink receiving layer, a commonly used blade coater, air knife coater, roll coater, brush coater, curtain coater, bar coater, gravure, and the like are used. A coater, a spray device, or the like can be used.

The coating amount of the dispersion was 0.5% in terms of dry solids.
The range of from 60 to 60 g / m ² is preferable since the ink absorbability becomes good, and the more preferable range is from 5 to 45 g / m ^2.
/ M ² , the ink absorption speed is increased, and cracks and powder fall are eliminated. If necessary, the surface smoothness of the ink receiving layer can be improved by using a calender roll or the like after coating, and the glossiness of the surface can be increased by performing cast molding.

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

The water-soluble dye is generally used by dissolving it in water or a solvent comprising water and a water-soluble organic solvent.
As these solvent components, a mixture of water and various water-soluble organic solvents is preferably used, and the mixture is adjusted so that the water content in the ink is in the range of 20 to 90% by weight. Is preferred.

Examples of the water-soluble organic solvent include alkyl alcohols having 1 to 4 carbon atoms such as methyl alcohol; amides such as dimethylformamide; ketones or ketone alcohols such as acetone; ethers such as tetrahydrofuran; Examples thereof include polyalkylene glycols such as glycol, alkylene glycols having an alkylene group having 2 to 6 carbon atoms such as ethylene glycol, and lower alkyl ethers of polyhydric alcohols such as glycerin and ethylene glycol methyl 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 nozzles from being reduced in clogging due to evaporation of water in the ink and precipitation of a water-soluble dye.

A solubilizing agent may be added to the ink. Typical solubilizers are nitrogen-containing heterocyclic ketones, the purpose of which is to significantly 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. Further improvement of characteristics,
For example, a surfactant for increasing the permeability of the ink component into plain paper, or an additive such as a viscosity adjuster, a surface tension adjuster, a pH adjuster, or a specific resistance adjuster can be used.

The method for forming an image by applying the ink to the recording medium is an ink jet recording method. In the recording method, the ink is effectively removed from the nozzles and the ink is applied to the recording medium. Any method may be used as long as it can be obtained. In particular, according to the method described in Japanese Patent Application Laid-Open No. 54-59936, 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.

[0078]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

The physical properties used in the present invention were measured as follows.

1. Crystallinity, parallelism From the X-ray diffraction pattern performed on the recording medium in the sheet shape as it is and on the powdery ink receiving layer separated from the recording medium, the intensity and strength at 2θ = 10 ° were obtained. The peak intensities of the (020) plane and the (120) plane were obtained. Further, the peak intensities of the (020) plane and the (120) plane were obtained from X-ray diffraction patterns performed on the ink receiving layer separated from the recording medium. Further, the crystallinity and the parallelism were determined by the following equations.

Crystallinity = peak intensity of (020) plane / 2
Intensity of θ = 10 ° Intensity ratio of powder = peak intensity of (020) plane of powder / peak intensity of (120) plane of powder Intensity ratio of medium (ink receiving layer) = peak intensity of (020) plane of medium / Peak intensity on the (120) plane of the medium Parallelism = Intensity ratio of medium / Intensity ratio of powder In the above, the X-ray diffraction measurement was performed under the following conditions.

Measuring device: RAD-2R (manufactured by Rigaku Denki Co., Ltd.) Target: Cu Kα Optical system: Wide-angle goniometer (with graphite curved monochromator) Goniometer radius: 185 mm Slit: DS1 ° RS1 ° SS0.15 mm X-ray output : 40 kV, 30 mA Measurement conditions: 2θ-θ method 2θ = 0.02 ° continuity scan 2θ = 10 to 90 ° 2 ° / min

2. BET specific surface area, pore volume The alumina hydrate and the recording medium were sufficiently heated and degassed and then measured using a nitrogen adsorption / desorption method.

Measuring apparatus: Autosoap 1 manufactured by Kantachrome Co., Ltd. 2-1. The BET specific surface area was calculated using the method of Brunauer et al. (J. Am. Chem. Soc., 60
Vol. 309, 1938) 2-2. The calculation of the pore volume used the method of Barrett et al. (J. Am. Chem. Soc., 73, 37)
3 pages, 1951)

3. Particle shape Alumina hydrate is dispersed in ion-exchanged water and dropped on a collodion membrane to prepare a sample for measurement. The sample is observed with a transmission electron microscope (H-500, manufactured by Hitachi, Ltd.) to determine the aspect ratio, The particle size was determined.

[0086] 4. Physical Properties of Coating Liquid 1) Dispersion State Evaluated by visual judgment. A sample which was in a good colloidal state without gelling or a precipitate and was in a good colloidal state was marked as “○”, and a sample in which gelation or a precipitate or an insoluble matter was formed and the dispersion was poor was marked as “x”.

2) Initial Viscosity At a temperature of 25 ° C., a B-type rotational viscometer (VISCOMMETER, manufactured by TOKIMEC) and a low viscosity adapter, N
o. The viscosity was measured using two rotors (rotation speed: 30 rpm).

3) Binder shock The state of thickening of the dispersion when mixing the water-soluble and / or water-dispersible polymer was evaluated by visual judgment. "X" indicates that the dispersion rapidly increased in viscosity and gelled, and "一度" indicates that the viscosity increased once immediately after the addition, and then returned to "△". What was maintained as it was was marked with “○”.

4) Pot rough After standing still in a closed container at a temperature of 25 ° C. for 10 days, the viscosity was measured under the same conditions as in 2), and the value of (temporary viscosity) / (initial viscosity) was determined.

5) pH at a temperature of 25 ° C., pH meter (manufactured by Horiba Ltd., Castany pH, meter D-14, pH electrode 63)
The pH was measured using 50-10-D).

6) Film-forming ability The alumina dispersion was gravure-coated at a coating speed of 200 m / min while performing a corona discharge treatment on a transparent polyester film (Lumilar T, manufactured by Toray Industries, Inc., thickness: 100 μm). It was coated and dried at 120 ° C. to form a coat layer. Even when the dry coating thickness is 40 μm or more, the coating layer is not cracked, and a uniform coating layer is formed as “「 ”. When the coating thickness is between 30 and 40 μm, the coating layer is cracked or damaged. "○", coating thickness 20-30μ
The case where cracks and flaws occurred in the coat layer between m was rated as “Δ”, and the case where cracks and flaws occurred in the coat layer even when the coating thickness was less than 20 μm was rated “x”. Cracks and scratches on the coat layer were evaluated by visual judgment.

7) Bulk-forming ability 15 ml of the alumina dispersion liquid was placed in a transparent polycup (120 cc Pack Ace manufactured by Teraoka Co., Ltd.), and dried in a dry oven at 100 ° C. for 24 hours without opening the lid. As a result, a gel-parc body was formed. If there was no crack, a bulk body that was not easily broken even when picked up was formed, `` ○ '', if there was no crack, but a bulk body that was easily broken when picked up was formed, `` △ '', Those in which cracks occurred and no bulk bodies were formed were rated "x". Cracks in the bulk were evaluated by visual inspection.

[0093] 5. Transparency The total light transmittance (%) of a sample in which an ink receiving layer was provided on a transparent PET film was measured using a haze meter (NDH-1001DP, manufactured by Nippon Denshoku Co., Ltd.) according to JIS K-7105.

6. Crack The length of the crack in the sample in which the transparent PET film was provided with the ink receiving layer was visually measured. When no cracks were visually observed, ○ was given when there was no crack of 5 mm or more, and X was given when cracks were 5 mm or more.

7. Glossiness A sample in which an ink receiving layer is provided on a white PET film is measured with a glossmeter (Gloss Checker IG-, manufactured by Horiba, Ltd.).
320 "(trade name)), the non-printed portion was measured at seven points, and the average value was determined.

8. Printing Characteristics Inkjet printer BJC-420 that strikes an inkjet head equipped with 128 nozzles for four colors of Y, M, C, and Bk at a noise interval of 16 nozzles per 1 mm.
J (manufactured by Canon Inc.) using regular ink cartridge BC-21 and photo ink cartridge BC-
22 (dye density: cyan (C), magenta (M): about 1/3 density, black B compared to regular ink)
k): about 1/2 density, yellow (Y): same density), and the following items 1) to 6) were evaluated for each cartridge. The evaluation of the printing characteristics was performed only on the recording medium in which the ink receiving layer was provided on the white PET film.

8-1. Evaluation items with regular ink 1) Ink absorbency After printing each of the Y, M, C, and Bk inks in a single color or multicolor, the ink dry state on the surface of the recording medium after touching the recording portion with a finger is examined. Was. Ink amount for single color printing is 1
00% (1 dot = 40 ng, 36 per square inch)
0 × 360 dots). In the same manner, 100% printing is performed with each of the three color inks, and the ink amount is 35%.
If the ink does not adhere to the finger at 0%, ○, ink amount 25
At 0%, the ink did not adhere to the finger, and when the ink adhered to the finger at 150%, it was evaluated as x.

2) Image Density The image density of an image printed solid with M ink at an ink amount of 100% was evaluated using a Macbeth densitometer RD1255 (in each case, the image density of M was the highest among the four colors). It was low, so it was evaluated here).

3) Bleeding, beading, and cissing After the solid ink of each of Y, M, C, and Bk was printed in a single color or multiple colors, the bleeding, beading, and cissing on the surface of the recording medium were visually evaluated. The ink amount in monochromatic printing was set to 100%. If the ink was not generated at 350% of the ink amount, ○;
If it occurred at 50%, it was evaluated as x.

4) Thickness of Characters The recorded images after printing the characters "Electrical surprise" in single or multiple colors using the respective inks of Y, M, C, and Bk were visually evaluated. The ink amount in monochromatic printing was set to 100%. A character with a clear edge and a sharp character was formed at 350% ink amount, and a character with a clear and sharp edge was formed at 250% ink amount. If you can't do it,
And

5) Migration Line widths 1, 3, and 5 on a 5 cm x 5 cm solid line
Y, M, C, B
After printing the k ink in single color and multicolor of each color so that the ink amount becomes 300%, the k ink was left in an environment of 30 ° C. and 80% RH for 7 days, and the recorded image after leaving was visually evaluated. If the white blank line with a line width of 1 mm remains without being crushed, it is ○. If the white blank line with a line width of 3 mm is left without being crushed, Δ is. And

6) Halftone Reproducibility After printing a black gradation pattern from 0 to 100% using the Y, M, C, and Bk inks, the color change of the recorded image was visually evaluated. When the halftone was formed without changing the color from black to gray and white, the result was evaluated as ○. When the halftone had a color different from gray, the result was evaluated as ×.

7) Roundness After printing one dot at a time using the Bk ink, d was measured when the major axis D and minor axis d of one dot were measured with a microscope.
/ D was defined as roundness.

8) Curl after printing 100% of each of C and Y inks on a recording medium of A4 size
Was printed over the entire surface in full size, and the maximum amount of curl immediately after paper ejection was measured with a gold scale. If the maximum curl amount is less than 10 mm,
Those with a diameter of 20 mm or more and less than 20 mm were marked with “△”, and those with 20 mm or more were marked with “x”.

8-2. Evaluation items for photo ink 1) Ink absorbency After printing each of Y, M, C, and Bk inks in a single color or multicolor, the ink dryness on the surface of the recording medium after touch printing is examined by touching the recording portion with a finger. Was. Ink amount for single color printing is 1
00% (1 dot = 40 ng, 36 per square inch)
0 × 360 dots). In the same manner, 100% printing is performed with each of the three color inks, and the ink amount is 35%.
If the ink does not adhere to the finger at 0%, ○, ink amount 25
At 0%, the ink did not adhere to the finger, and when the ink adhered to the finger at 150%, it was evaluated as x.

2) Image Density The image density of an image obtained by solid-printing a single color three times with M ink so that the ink amount becomes 300% was evaluated using a Macbeth reflection densitometer RD1255 (in each case, the image density was evaluated). Since the image density of M was the lowest among the four colors, it was evaluated here.)

3) Bleeding, beading, and cissing After the solid ink of each of Y, M, C, and Bk was printed in a single color or multiple colors, the bleeding, beading, and cissing on the surface of the recording medium were visually evaluated. The ink amount in monochromatic printing was set to 100%. When the ink was not generated at the ink amount of 350%, it was evaluated as 、.

4) Character Thickness The recorded images after printing the characters "Electrical surprise" in single color or in multiple colors with each of the Y, M, C, and Bk inks were visually evaluated. The ink amount in monochromatic printing was set to 100%. A character with a clear edge and a sharp character was formed at 350% ink amount, and a character with a clear and sharp edge was formed at 250% ink amount. If you can't do it,
And

5) Migration Four lines vertically, horizontally and vertically on a 5 cm × 5 cm solid
Y, M, C, B
After printing the k ink in single color and multicolor of each color so that the ink amount becomes 300%, the k ink was left in an environment of 30 ° C. and 80% RH for 7 days, and the recorded image after leaving was visually evaluated. If the white blank line with a line width of 1 mm remains without being crushed, ○ is displayed. If the white blank line with a line width of 3 mm remains without being crushed, Δ is displayed. X.

6) Halftone Reproducibility After printing a black gradation pattern from 0 to 300% using Y, M, C, and Bk inks, the change in the tint of the recorded image was visually evaluated. When the halftone was formed without changing the color from black to gray and white, the result was evaluated as ○. When the halftone had a color different from gray, the result was evaluated as ×.

7) Roundness After printing one dot at a time using Bk ink, d was measured when the major axis D and minor axis d of one dot were measured with a microscope.
/ D was defined as roundness.

Production Examples of Alumina Hydrate Aluminum dodecoxide was produced 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 this alumina slurry to adjust the alumina hydrate solids to 7.9%. The pH of this alumina slurry was 9.5.

A pH was adjusted by adding a 3.9% nitric acid solution to the slurry, and a colloidal sol was obtained under the respective aging conditions shown in Table 1. The colloidal sol was spray-dried at 75 ° C. to obtain alumina hydrates (A and B) shown in Table 1.

The BET specific surface area and pore volume of these alumina hydrates were determined by the following methods.

The pore volume (PV) was measured by degassing at 120 ° C. for 24 hours and then using an auto soap (trade name, manufactured by Kantakraw) by a nitrogen adsorption / desorption method.

The BET specific surface area (SA) is
It was calculated using the method of r et al.

Table 1 shows the results.

[0118]

[Table 1]

Production Example of Alumina Hydrate Aluminum dodecoxide was produced by the method described in US Pat. No. 4,242,271. Next, the aluminum dodoxide 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 having a boehmite structure had a solid content of 7.9%. The pH of the alumina slurry was 9.2. 3.9
% Nitric acid solution was added to adjust the pH, and a colloidal sol was obtained under the respective aging conditions shown in Table 1. This colloidal sol was spray-dried at 85 ° C. to produce an alumina hydrate powder having a boehmite structure. The crystal structure of the alumina hydrate was boehmite, and the particle shape was a flat plate shape. The physical properties of the alumina hydrate were measured by the above methods. Table 2 shows the results.

[0120]

[Table 2]

Example 1 Zirconium oxychloride hydrate (ZC) (weight: 8.0% in terms of ZrO ₂ ) was added to 390 parts by weight of ion-exchanged water.
8 parts by weight and 110 parts by weight of alumina hydrate A were sequentially added, and 1500 r was added using a disperser (TK Robomix, homodisper 2.5 type, manufactured by Tokushu Kika Kogyo Co., Ltd.).
After stirring at 30 rpm for 30 minutes, the rotation speed was further increased to 2500 rpm.
And while stirring continuously, add a 10% aqueous solution of polyvinyl alcohol (GH-
17) (PVA) was mixed with 157 parts by weight, and the mixture was further stirred for 30 minutes, and the weight ratio of alumina hydrate to polymer (P /
B) was 7/1 to obtain an alumina dispersion having a solid content of 19.9% by weight.

The physical properties of the alumina dispersion were evaluated by the above-mentioned measuring methods. The results are shown in Table 3.

Examples 2 to 5 The addition amount of zirconium oxychloride hydrate (ZC) in Example 1 was 1.13 × 10 ⁻³ parts by weight in case of 2, and 0.02 in case of 3
An alumina dispersion was obtained in the same manner as in Example 1, except that 1 part by weight, 4 for 20.2 parts by weight, and 5 for 41.3 parts by weight, respectively. Table 3 shows the results of measurement and evaluation by the same method.
Shown in

Examples 6 and 7 The zirconium oxychloride hydrate (ZC) of Example 1 and the amount of zirconium oxychloride added thereto were determined in Example 6 by using zirconyl nitrate hydrate (ZN,
1.8 parts by weight of ZrO ₂ equivalent content (46.0%), and in Example 7, zirconyl acetate (ZA, ZrO ₂ equivalent content of 5 parts by weight)
(4.7%) was changed to 1.5 parts by weight, respectively, to obtain an alumina dispersion liquid in the same manner as in Example 1. Table 3 shows the results of measurement and evaluation in the same manner.

Examples 8 to 11 In Example 8, 917 parts by weight of an aqueous 10% polyvinyl alcohol solution was used instead of alumina hydrate B in Example 6, 367 parts by weight in Example 9, and 55% in Example 10 .
An alumina dispersion was obtained in the same manner as in Example 6, except that 0 part by weight and Example 3 were replaced with 39.3 parts by weight, respectively. Table 3 shows the results of measurement and evaluation in the same manner.

Examples 12 to 13 The alumina hydrate of Example 6 was replaced with B, and a 10% aqueous solution of polyvinyl alcohol and the amount of addition thereof were changed to a 10% aqueous solution of polyvinylpyrrolidone (Kyoto Sangyo Co., Ltd., K
In Example 13, the addition amount was 28.7 parts by weight, and the polyvinyl acetate resin emulsion (Sybinol AS-550, solid content: 54.7% by weight) was added. An alumina dispersion was obtained in the same manner as in Example 6, except that each mixture was mixed with 128.3 parts by weight of ion-exchanged water. Table 3 shows the results of measurement and evaluation in the same manner.

[0127]

[Table 3]

Example 14 1.8 parts by weight of zirconyl nitrate hydrate (ZN; content: 46.0% in terms of ZrO ₂ ), 110 parts by weight of alumina hydrate B, 0 parts of formic acid based on 390 parts by weight of ion-exchanged water .65 parts by weight were added sequentially, and a dispersing machine (manufactured by Tokushu Kika Kogyo Co., Ltd.)
T. K. (Robomix, homodisper 2.5 type) for 30 minutes at 1500 rpm, and while continuing stirring under the same conditions, 1 part of polyvinyl alcohol was added to the dispersion.
0% aqueous solution (GH-17, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
(PVA) was mixed with 157 parts by weight, and the mixture was further stirred for 30 minutes to obtain a weight ratio of alumina hydrate to polymer, P / B of 7/7.
1. An alumina dispersion having a solid content of 19.7% by weight was obtained.

The physical properties of the alumina dispersion were evaluated by the above-mentioned measuring methods. The results are shown in Table 4.

Examples 15 to 17 The amount of formic acid added in Example 14 was 0.030 in Example 15.
Alumina dispersion liquid was obtained in the same manner as in Example 14 except that the weight was changed to 28.6 parts by weight in Example 16, 28.6 parts by weight in Example 16, and 46.0 parts by weight in Example 17. Table 4 shows the results measured by the same method.

Examples 18 to 19 Example 14 is the same as Example 14 except that the formic acid and the amount of addition were 1.26 parts by weight of lactic acid in Example 18, and 1.75 parts by weight of oxalic acid in Example 19. An alumina dispersion was obtained in the same manner as described above. Table 4 shows the results measured in the same manner.
Shown in

[0132]

[Table 4]

Example 20 Zirconium oxychloride hydrate (concentration in terms of oxide of 38.0% based on 390 parts by weight of ion-exchanged water: ZC
3.8 parts by weight) and 110 parts by weight of alumina hydrate C were successively added, and a dispersing machine (TK.
Robomix, homodisper 2.5)
After stirring at 00 rpm for 30 minutes, the rotation speed was further increased to 2
157 parts by weight of a 10% aqueous solution of polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., Gohsenol GH17) was mixed with this dispersion while stirring at 500 rpm, and the mixture was further stirred for 30 minutes to obtain alumina hydrate. A coating liquid having a weight ratio of the polymer to the polymer of 7/1 and a solid concentration of 19.9% by weight was obtained.

While applying a corona discharge treatment on a transparent and white PET film (Lumirror, trade name, manufactured by Toray Industries, Inc.) of 100 μm as a support, the coating solution was gravure coated at a coating speed of 10 m / min. After drying at 120 ° C., an ink receiving layer having a dry coating thickness of 40 μm was formed to obtain a recording medium of the present invention. The obtained recording medium is ESCA
As a result, no Al-O-Zr bond was observed. Physical property values were measured by the methods described above. Table 5 shows the measurement results.

Examples 21 to 23 A recording medium was obtained in the same manner as in Example 20, except that the alumina hydrate of Example 20 was replaced with the alumina hydrate of Synthesis Examples 4 to 6, respectively. When the obtained recording medium was measured by ESCA, no Al-O-Zr bond was observed. Table 5 shows the results of measurement and evaluation by the same method.

Examples 24 to 25 The amount of ZC added in Example 20 was 0.021 in Example 24.
The recording medium was obtained in the same manner as in Example 20, except that the weight was changed to 20.2 parts by weight in Example 25. When the obtained recording medium was measured by ESCA, Al-
No O-Zr bond was observed. Table 5 shows the results of measurement and evaluation by the same method.

Examples 26 to 27 In Example 26, ZC of Example 20 and the amount of ZC added were 1.8 parts by weight of zirconyl nitrate (content in terms of oxide: 46.0%; hereinafter abbreviated as ZN). Then, a recording medium was obtained in the same manner as in Example 20, except that zirconyl acetate (content in terms of oxide: 54.7%; hereinafter abbreviated as ZA) was changed to 1.5 parts by weight. ESC the obtained recording medium
As measured by A, no Al-O-Zr bond was observed. Table 5 shows the results of measurement and evaluation by the same method.

[0138]

[Table 5]

Example 28 1.8 parts by weight of ZN, 110 parts by weight of alumina hydrate B, and 0.65 parts by weight of formic acid were sequentially added to 390 parts by weight of ion-exchanged water. Manufactured by TK.
Robomix, homodisper 2.5)
After stirring at 00 rpm for 30 minutes, a 10% aqueous solution of polyvinyl alcohol (Gosenol GH, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was added to the dispersion while stirring under the same conditions.
157 parts by weight of 17) were mixed and further stirred for 30 minutes to obtain a coating liquid having a weight ratio of alumina hydrate to polymer of 7/1 and a solid content of 19.7% by weight.

While applying a corona discharge treatment on a 100 μm transparent and white PET film (Lumirror, trade name, manufactured by Toray Industries Inc.) as a support, the coating solution was gravure coated at a coating speed of 10 m / min. By drying at 120 ° C., an ink receiving layer having a dry coating thickness of 40 μm was formed, thereby obtaining a recording medium of the present invention. The obtained recording medium is ESCA
As a result, no Al-O-Zr bond was observed. Physical property values were measured by the methods described above. Table 6 shows the measurement results.

Examples 29 to 30 The amount of formic acid added in Example 28 was 0.030 in Example 29.
A recording medium was obtained in the same manner as in Example 28, except that the weight was changed to 28.6 parts by weight, and in Example 30 to 28.6 parts by weight. When the obtained recording medium was measured by ESCA, Al-
No O-Zr bond was observed. Table 6 shows the results of measurement and evaluation by the same method.

Examples 31 to 32 The same procedures as in Example 28 were carried out except that the formic acid and the added amount were changed to 1.26 parts by weight of lactic acid in Example 31 and 1.75 parts by weight of oxalic acid in Example 32. The same operation as in Example 30 was performed to obtain a recording medium. When the obtained recording medium was measured by ESCA, no Al-O-Zr bond was observed.
Table 6 shows the results of measurement and evaluation by the same method.

Comparative Example 1 Pseudo-boehmite sol (catalyst AS, manufactured by Sekiyu Kasei Kogyo Co., Ltd.)
-3, solid content concentration of 7% by weight) using a dispersing machine (TK Robomix, Homodisper 2.5 type, manufactured by Tokushu Kika Kogyo Co., Ltd.) at 500 rpm, and stirring the polyvinyl alcohol at 2500 rpm. A 10% aqueous solution of alcohol (Gohsenol GH17, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
Parts by weight and stirred for 30 minutes to obtain a coating liquid having a weight ratio of alumina hydrate to polymer of 7/1 and a solid content of 7.3% by weight.

Thereafter, a recording medium was obtained in the same manner as in Example 20. Physical property values were measured by the methods described above. Table 6 shows the measurement results.

Comparative Example 2 1.7 parts by weight of ZC and 500 parts by weight of amorphous alumina sol (alumina sol 100, solid content concentration: 10% by weight) were added to 214 parts by weight of ion-exchanged water. Dispersing machine (Toki KK)
Robomix, homodisper 2.5)
After stirring at 00 rpm for 30 minutes, the dispersion was further increased to 4000 rpm, and while continuing to stir, 50% by weight of a 10% aqueous solution of polyvinyl alcohol (Gosenol GH17, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was added to the dispersion. Then, the mixture was further stirred for 30 minutes to obtain a coating liquid having a weight ratio of amorphous alumina to polymer of 7/1 and a solid content of 7.5% by weight.

Thereafter, a recording medium was obtained in the same manner as in Example 20. Physical property values were measured by the methods described above. Table 6 shows the measurement results.

Comparative Example 3 Example 2 was repeated except that alumina hydrate A in Example 20 was replaced with silica (Mizukasil P-78A, manufactured by Mizusawa Chemical Industry Co., Ltd.).
In the same manner as in Example No. 0, a recording medium was obtained. Physical property values were measured by the methods described above. Table 6 shows the measurement results.

[0148]

[Table 6]

[0149]

The recording medium of the present invention has a wide selection range of inks, has a small migration and bleeding, has a high optical density in a printing portion, and has good gloss and transparency. Excellent halftone reproducibility. Further, the dispersion stability of the coating liquid is excellent, and since the pH is high, there are few problems such as corrosion, so that a recording medium can be manufactured without requiring special manufacturing equipment.

Further, the alumina dispersion of the present invention has excellent binding properties and shape imparting properties, has a low viscosity at a high solid content, has excellent dispersion stability, and has a long pot life.

Further, the alumina dispersion of the present invention can be easily produced without requiring any special production equipment.

Claims (30)

[Claims] 1. A recording medium comprising an ink receiving layer formed on a substrate, wherein the ink receiving layer contains an alumina hydrate having a boehmite structure and a non-coupling zirconium compound. Recording medium characterized by the following. 2. The recording medium according to claim 1, wherein the zirconium compound is an inorganic salt and / or an organic acid salt of zirconium. _3. The ratio of the weight of the zirconium compound in terms of ZrO _{2 to the} weight of the alumina hydrate in terms of Al ₂ O ₃ (ZrO ₂ / Al ₂ O ₃ ) is 1.0 × 10 ^{−4 to} 1.0 ×.
2. The recording medium according to claim ^1, which is 10 ^-1 . 4. The recording medium according to claim 1, wherein the ink receiving layer further contains one or more organic acids. 5. The content of the organic acid is 5.0 × 1 in terms of moles based on the weight of the zirconium compound in terms of ZrO _2.
0 The recording medium according to claim 4 in the range of ^-4 mol / ^g~1.0mol / g. 6. The recording medium according to claim 1, wherein the average particle diameter or the average particle length of the alumina hydrate is in a range of 1 to 50 nm. 7. The recording medium according to claim 1, wherein the average aspect ratio of the alumina hydrate is in a range of 3 to 10. 8. The crystallinity of the alumina hydrate is 15 to
The recording medium according to claim 1, wherein the number is in the range of 80. 9. The parallelism between the microcrystals of the alumina hydrate and the in-plane direction of the ink receiving layer is 1.5 or more.
A recording medium according to claim 1. 10. The recording medium according to claim 1, wherein the BET specific surface area of the alumina hydrate is in a range of 40 to 500 m ² / g. 11. The alumina hydrate having a pore volume of 0.1.
The recording medium according to claim 1 which is in the range of 1~1.0cm ³ / g. 12. The recording medium according to claim 1, wherein the ink receiving layer further contains a binder. 13. The method according to claim 1, wherein the mixing ratio of the alumina hydrate and the binder is in the range of 1: 1 to 30: 1 on a weight basis.
3. The recording medium according to 2. 14. The method according to claim 1, wherein the mixing ratio of the alumina hydrate and the binder is in the range of 3: 1 to 20: 1 on a weight basis.
4. The recording medium according to 3. 15. The ink receiving layer having a BET specific surface area of 40
The recording medium according to claim 1 in the range of ~450m ² / g. 16. The ink receiving layer having a pore volume of 0.1 to 0.1.
2. The recording medium according to claim 1, wherein the recording medium is in a range of 1.0 cm ³ / g. 17. An image forming method in which ink is ejected from a fine hole and applied to a recording medium to perform printing, wherein the recording medium according to claim 1 is used as the recording medium. Characteristic image forming method. 18. The image forming method according to claim 17, wherein thermal energy acts on the ink to eject the ink droplet. 19. In producing a recording medium by forming an ink receiving layer on a substrate, a dispersion containing a boehmite-structured alumina hydrate, a non-coupling zirconium compound, and a binder is used. A method for manufacturing a recording medium, wherein the method is applied to a material and dried to form an ink receiving layer. 20. The method according to claim 19, wherein the dispersion further contains one or more organic acids. 21. An alumina dispersion comprising an alumina hydrate, a binder, and an inorganic and / or organic acid salt of zirconium. 22. The ratio Z between the weight of the zirconium salt in terms of ZrO _{2 and the} weight of the alumina hydrate in terms of Al ₂ O _3.
rO ₂ / Al ₂ O ₃ is 1.0 × 10 ^{−4 to} 1.0 × 10 ⁻¹
The alumina dispersion according to claim 21, which is in the range of: 23. The mixing ratio of the alumina hydrate and the binder is in the range of 1: 1 to 30: 1 on a weight basis.
2. The alumina dispersion according to 1. 24. The alumina dispersion according to claim 21, wherein one or more organic acids are contained in the alumina dispersion. 25. The content of the organic acid is in the range of 5.0 × 10 ⁻⁴ mol / g to 1.0 mol / g as the number of moles of the organic acid with respect to the weight of zirconium salt in terms of ZrO _2. An alumina dispersion according to claim 24. 26. A process for producing an alumina dispersion, which comprises mixing and dispersing a binder into a dispersion containing an alumina hydrate and an inorganic and / or organic salt of zirconium. 27. A ratio Z between the weight of the zirconium salt in terms of ZrO _{2 and the} weight of the alumina hydrate in terms of Al ₂ O _3.
rO ₂ / Al ₂ O ₃ is 1.0 × 10 ^{−4 to} 1.0 × 10 ⁻¹
The method for producing an alumina dispersion according to claim 26, wherein 28. The mixing ratio of alumina hydrate and binder is in the range of 1: 1 to 30: 1 on a weight basis.
7. The method for producing an alumina dispersion according to item 6. 29. The method for producing an alumina dispersion according to claim 26, wherein the dispersion contains one or more organic acids. 30. The content of the organic acid is in the range of 5.0 × 10 ⁻⁴ mol / g to 1.0 mol / g as the number of moles of the organic acid with respect to the weight of the zirconium salt in terms of ZrO _2. 30. The method for producing an alumina dispersion according to claim 29.