JPH08325992A - Medium to be recorded - Google Patents

Abstract

PURPOSE: To obtain a medium to be recorded having stabilize quality excellent in ink absorption and water resistance and resistant to beating by coating the base with the solution comprising particulate alumina hydrate and an anionic resin emulsion to form the ink-receiving layer. CONSTITUTION: (A) Particulate alumina hydrate is mixed with (B) an anionic resin emulsion having a lowest film-forming temperature of 0-50 deg.C which is prepared by emulsifying a binder resin, for example, polyvinyl acetate with a glass transition point of 0-90 deg.C having particle sizes of 0.07-0.7μm at a weight ratio of 1/1-9/1, preferably 2/1-7/1 to prepare the coating solution where the pH of alumina hydrate coating solution in the equal amount of ion-exchanged water (pHA) and the pH of anionic resin emulsion (pHB) satisfy the relation, pHA-pHB<=±2. This coating solution is applied to the base such as polyester film to form the ink-receiving layer whereby the objective medium to be recorded is obtained. Various color inks are jetted from the nozzles at the head in the form of fine drops to this paper based on the recording signals to effect ink-jet printing whereby an image is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium used for recording with ink, and particularly to a recording medium suitable for recording using an aqueous ink such as ink jet recording, an image forming method using the recording medium, and a method for producing the same. Regarding

[0002]

2. Description of the Related Art Ink jet recording is a system for ejecting minute droplets of ink according to various operating principles and adhering them to a recording medium such as paper to record images, characters, etc. It has the features that it can be multi-colored, the flexibility of recording patterns is great, and that development and special fixing processing are not required. It is rapidly becoming popular in various applications.

According to this multicolor ink jet system, it is possible to obtain an image which is comparable to the multicolor printing by the plate making system or the printing by the color photographic system, and when the number of copies is small. It is suitable for cases where a large number of copies are not required because it is cheaper than that for ordinary multicolor printing or printing, and the range of application of the inkjet system has expanded to the field of full-color image recording.

In order to cope with such rapid expansion of the application field, the recording apparatus and the recording method have been improved in order to further improve the recording characteristics such as high speed recording, high definition recording and full color recording. Higher characteristics have come to be required for recording media as well.

In order to meet such requirements, various types of recording media have been proposed in the past. For example, JP-A-55-5830 discloses an ink jet recording paper which has an ink-absorbing coating layer on the surface of a support as an ink receiving layer, and JP-A-55-51583 discloses an ink receiving sheet. An example using amorphous silica as a pigment in a coating layer as a layer and an example using a water-soluble polymer coating layer as an ink receiving layer are disclosed in JP-A-55-146786. ing.

A recording medium having a coating layer using alumina hydrate having a boehmite structure has also been proposed, for example, US Pat. Nos. 4,879,166 and 51047.
No. 30, JP-A-2-276670, and JP-A 3-2.
No. 75378, No. 3-281384, No. 5-
No. 32037 is disclosed.

Further, US Pat. No. 4,374,804,
JP-A-5104730, JP-A-58-110287, JP-A-1-97678, and JP-A-2-27667.
As disclosed in Japanese Patent Laid-Open No. 1-37456 and Japanese Patent Laid-Open No. 4-37576, a silica or alumina material is used to form an ink receiving layer having a multi-layered structure.

The recording medium using these alumina hydrates has a good fixing property for coloring materials such as dyes in the ink and a good coloring property because the alumina hydrates are cationic, that is, have a positive charge. In comparison with conventional recording media, it is possible to obtain an image, to solve the problem of browning and light resistance of black ink in the case of using a conventional silica compound, and further in terms of image quality, especially in a full-color image. It has advantages such as being good.

However, the conventional recording medium using alumina hydrate is not always able to sufficiently cope with the ink absorptivity when a large amount of ink is adhered, such as in multicolor ink jet color recording. .

For example, in printing a color image, the amount of ink applied to the recording medium is large, so that a higher ink absorbency is required. Therefore, even if the ink absorbability that can be used for recording in a single color but does not have the ink absorbability applicable to color image recording, the ink does not fit in the pores and overflows on the surface. The image quality is deteriorated due to the occurrence of. In high-speed printing, fast drying property is required, but if the ink absorption speed is insufficient, the output image surface cannot be sufficiently dried, and for example, when the print is discharged from the device after printing. There is a problem that the output image is damaged due to the contact of the output image with the inside of the device or the like.

For example, 1) US Pat. No. 5,104,730, JP-A-2-27
No. 6670, No. 2-276671, No. 3-2.
The ink receiving layer of the recording medium of Japanese Patent No. 75378 has an extremely narrow range of pore diameters. However, JP-A-4-
As described in JP-A-267180 and JP-A-5-16517, a specific color material (for example, for cyan, magenta, yellow, and black) such as various dyes used for color ink and a solvent component are Some of them are selectively absorbed or adsorbed in a range of pore diameters. If the pore diameter range is extremely narrow as described above, it may not be possible to adequately support a wide range of ink compositions for color recording, and some inks may not be compatible. Bleeding becomes noticeable.

2) In US Pat. No. 5,104,730, JP-A-2-276670, JP-A-2-276671, and JP-A-3-275378, the average pore diameter is 10
A recording medium having a pore size distribution of up to 30 Å is disclosed. With this pore size distribution, the dye adsorbability is good, but the ink solvent component absorbency is insufficient, and thus beading, that is, bead spheres. In many cases, visually recognized color unevenness occurs.

3) Japanese Patent Application Laid-Open No. 3-281384 discloses that
Disclosed is a hydrated alumina that forms a tufted bundle-like aggregate having an aspect ratio of 3 or less and oriented in a fixed direction, and a method for forming an ink receiving layer using the same. But,
In such an ink receiving layer, since the alumina hydrate is oriented and densely packed, the interval between the alumina hydrate particles in the ink receiving layer is likely to be narrowed. Therefore, the pore diameter tends to be narrower and the pore diameter distribution tends to be narrower. as a result,
Similar to the above, there is a problem that beading occurs.

On the other hand, in a recording medium using a multi-layered ink receiving layer, coating and drying steps are required for forming each layer, resulting in an increase in the number of steps, resulting in cost increase, cracking of the ink receiving layer, and printing. There is a problem that peeling or the like between later layers is likely to occur.

Furthermore, the coating liquid used in the formation of the ink receiving layer using alumina hydrate usually contains alumina hydrate and a binder polymer (water-soluble polymer etc.), and is prepared depending on its composition. There is also a problem that the viscosity increases with the passage of time later and the handling becomes difficult. To solve this problem, it is preferable to use a binder polymer having a low degree of polymerization as disclosed in JP-A-4-6.
It is disclosed in Japanese Patent Publication No. 7986. However, the ink receiving layer having such a composition has problems such as generation of cracks and deterioration of water resistance, and is not a sufficiently effective solution.

[0016]

DISCLOSURE OF THE INVENTION According to the studies made by the present inventors, a means for further improving the ink absorbency of a recording medium having an ink receiving layer using the above-mentioned conventional alumina hydrate has been investigated. The ink absorptivity of the ink receiving layer strongly depends on the layer thickness, and is 25 to obtain a sufficient ink absorptivity even when a large amount of ink is applied such as in color inkjet recording.
It has been found that a layer thickness of about μm or more, preferably about 30 μm or more is required.

However, when an ink receiving layer having the above-mentioned layer thickness is formed with a coating liquid composition containing a conventional alumina hydrate and a polymer binder, an ink receiving layer of good quality cannot be efficiently obtained. Have difficulty.

For example, when the ink receiving layer has a multi-layered structure and the layer thickness is increased, coating and drying steps are required for each layer, which causes a problem of cost increase due to an increase in the number of steps as a whole. Further, as a problem peculiar to the multi-layered structure, the frequency of occurrence of problems such as cracks, peeling between layers, inclusion of bubbles, etc. is high, so special consideration is required to prevent such problems from occurring.

On the other hand, when a thick coating layer is obtained by a single coating, a long period of time is required for coating and drying the coating layer, resulting in lower productivity and higher cost. Also, depending on the composition of the coating liquid, the viscosity increases with time after preparation,
It may be difficult to handle. In addition, a coating machine with a long drying oven may be required.

There is also a method of increasing the solid content concentration of the coating solution to increase the layer thickness of the coating layer after drying, but such a coating solution often has a high viscosity at the time of preparation. There is also a problem in terms of handleability, and in many cases the viscosity increases further after preparation, which makes it difficult to apply the coating solution once it has been prepared and the production efficiency decreases. .

The present invention has been made to solve the above problems in the ink receiving layer using the hydrated alumina, and the object thereof is to solve the problems in thickening the ink receiving layer. It is an object of the present invention to provide a recording medium having an ink receiving layer which is as thin as possible and has excellent ink absorbency and which maintains the advantages of using an alumina hydrate.

[0022]

The recording medium of the present invention comprises:
In a recording medium having an ink receiving layer provided on a substrate, the ink receiving layer is formed by applying a coating liquid mainly composed of a particulate alumina hydrate and an anionic resin emulsion onto the substrate and drying. It is obtained by doing.

The alumina hydrate used for forming the ink receiving layer is not particularly limited as long as the object of the present invention can be achieved. For example, the following general formula:

[0024]

Embedded image Al ₂ O _3−n (OH) _2n · mH ₂ O (wherein n is 0, 1, 2 or 3, and m is 0 to
In the range of 10, preferably 0 to 5, mH ₂ O represents a detachable aqueous phase which is not often involved in the formation of a crystal lattice, and therefore m may be a non-integer value. Further, when calcined, m may reach 0. Those represented by) can be preferably used. Further, the hydrated alumina is amorphous, especially Japanese Patent Application No. 5-125.
No. 437, No. 5-125438, No. 5-12
Alumina hydrates described in JP-A-5439 and JP-A-6-114571 are preferable. Whether or not the alumina hydrate is amorphous can be confirmed by analysis by an X-ray diffraction method or the like.

Alumina hydrate is used for forming the ink receiving layer, either directly or in the form of being dispersed in water or a liquid medium containing water as a main component, by being mixed with an anionic resin emulsion described later. By including alumina hydrate in the ink receiving layer, it becomes possible to impart a porous structure to the ink receiving layer.

The porous structure of the ink receiving layer can be characterized by, for example, the pore volume and the BET specific surface area. To achieve the object of the present invention, the pore volume of the ink receiving layer is preferably in the range of 0.1 to 1.0 ml / g. If the pore volume of the ink receiving layer is larger than the above range, cracks and powder falling off easily occur in the ink receiving layer, and if it is smaller than the above range, sufficient ink absorbency cannot be obtained, In some cases, when multicolor printing is performed, the ink may overflow from the ink receiving layer to cause bleeding in the image.

The BET specific surface area of the ink receiving layer is
It is preferable that the range is ^{20 to} 450 m ² / g.
If it is less than this range, sufficient glossiness may not be obtained in the ink receiving layer, and haze may be increased, so that white mist appears on the image. If it is larger than the above range, cracks are likely to occur in the ink receiving layer.

In order to obtain an ink receiving layer having such preferable pore volume and BET specific surface area, the pore volume of hydrated alumina is in the range of 0.1 to 1.0 ml / g. Preferably, the BET specific surface area is 40-5.
It is preferably 00 m ² / g. The physical properties such as the pore volume of the alumina hydrate can be adjusted during the manufacturing process.

The alumina hydrate is preferably in the form of porous particles having a particle size of 20-5.
It is preferably 00 nm. For example, when a particle size smaller than this range is used, cracks may easily occur, and when a particle size larger than this range is used, the surface smoothness of the ink receiving layer is May decrease and the image may become whitish due to light scattering.

In the present invention, the resin binder used for forming the ink receiving layer may be any resin as long as it can form an anionic resin emulsion and satisfies the function as a binder. Examples of such a resin include acrylic, polyurethane, vinylidene chloride, polyolefin, polyvinyl acetate, styrene-acrylic copolymer, ethylene-vinyl acetate copolymer, polyvinyl butyral and the like. The binder resin may be used alone or in combination of two or more. By selecting a hydrophobic binder resin, the water resistance of the ink receiving layer is significantly improved.

The binder resin is used as an anionic resin emulsion in the preparation of a coating liquid. This anionic resin emulsion is one in which binder resin particles are dispersed in an aqueous liquid medium, and the surface of the resin particles in a dispersed state is made anionic by selecting the type of monomer or surfactant used for emulsion polymerization. Of these, known emulsions of the various resins described above can be selected and used according to the purpose. Further, as the anionic resin emulsion, for example, the minimum film forming temperature is 0.
It is preferably in the range of -50C and the glass transition temperature of the dispersed binder resin is in the range of 0-90C.

When the minimum film-forming temperature or the glass transition temperature is lower than the above range, the ink absorbency may decrease due to the decrease in the pore volume over time after the ink receiving layer is formed. There may be a problem that the surface becomes sticky or that the surface is easily damaged due to a decrease in surface hardness.

On the other hand, if the temperature is higher than the above temperature range, problems such as deformation of the substrate often occur in the heating and drying temperature range required for sufficient film formation, which is not preferable. That is, in low-temperature (heating) drying at which the substrate does not deform,
Problems such as the occurrence of cracks in the ink-receiving layer that is formed due to the decrease in film-forming property due to fusion between emulsification particles, and the appearance of white mist on the entire image due to the formation of large pores. Occurs.

On the other hand, the particle size of the resin particles dispersed in the emulsion is preferably, for example, in the range of 0.07 to 0.7 μm. If the particle size is smaller than this range,
Good pore formation may not be achieved, and if the particle size is larger than this range, there may be a problem that the pore size becomes too large and white mist appears on the entire image. .

As the base material, papers such as appropriately sized papers, non-sized papers, resin-coated papers, resin films and sheets, cloths and the like can be used without any particular limitation.
As a resin, opaque by filling transparent film or sheet of polyester, polystyrene, polyvinyl chloride, polymethylmethacrylate, cellulose acetate, polyethylene, polycarbonate, etc., alumina hydrate, titanium white, etc., or by foaming. It is possible to use a film or sheet prepared by the above.

The surface of the substrate may be subjected to surface treatment such as corona treatment or a simple adhesive layer may be provided as an undercoat layer in order to improve the adhesiveness to the ink receiving layer. Further, for curl prevention, a curl prevention layer such as a resin layer or a pigment layer may be provided on the back surface of the substrate or a predetermined portion.

The coating liquid for forming the coating layer is prepared by mixing at least alumina hydrate and an anionic resin emulsion. As a method for preparing the coating liquid,
Examples thereof include a method of adding alumina hydrate to an anionic resin emulsion, and a method of mixing an aqueous dispersion of alumina hydrate with an anionic resin emulsion.

PH value given by alumina hydrate (pH _A )
And the pH value (pH _E ) of the anionic resin emulsion are preferably mixed in a state of satisfying the relationship of pH _A −pH _E ≦ 2. If the pH difference between the two exceeds 2,
Dispersion of one or both of the alumina hydrate particles and the anionic resin particles is destroyed, and gelation or precipitation of the particles occurs, making it difficult to form the ink receiving layer well.

When the alumina hydrate is directly added to the anionic resin emulsion to obtain a coating liquid, the pH _A given by the alumina hydrate is added to ion-exchanged water of the same volume as the coating liquid. Is the pH value obtained when the same amount of alumina hydrate is added, and when mixing the aqueous dispersion of alumina hydrate and the anionic resin emulsion, the aqueous dispersion of alumina hydrate PH value of. Incidentally, the pH of the aqueous dispersion of alumina hydrate or the anionic resin emulsion can be adjusted by using an appropriate acid or base within a range that does not impair the dispersed state of the particles so as to satisfy the above relationship.

In addition, pH _A- pH _E ≤ ± 1
It is more preferable because it is possible to further improve the coating suitability by lowering the viscosity of the coating liquid.

The hydrated alumina is preferably one which gives a pH _A in the range of 2.5 to 6.0 in the dispersion having a solid concentration by weight of 10 to 20%. When an alumina hydrate that gives a value lower than this range is used, discoloration of the image may occur, and if it exceeds this range, the coating may be difficult to handle or coating may not be possible. It is not preferable because the viscosity of the working fluid may increase or the viscosity increasing rate may increase with the lapse of time after preparation of the coating fluid.

The pH of the anionic resin emulsion
_E is preferably in the range of 2.0 to 7.0. If it is out of this range, problems such as gelation and generation of precipitates may occur when mixed with alumina hydrate.

The weight mixing ratio of the alumina hydrate and the binder resin (solid content of the anionic resin emulsion) is, for example, a lower limit of 1: 1, preferably 2: 1 and an upper limit of 9: 1. , Preferably 7: 1. When the amount of the binder resin is less than the above range, the mechanical strength of the ink receiving layer may be reduced, cracks may occur, and powder may fall off.If the amount is more than the above range,
There is a case where a sufficient porous structure, for example, a pore volume is not obtained in the ink receiving layer and the ink absorbability is lowered.

The pH of the coating solution itself is preferably 3 to 7.
When the ink receiving layer is formed using a coating liquid having a pH lower than 3, discoloration of the printed ink may easily occur. Further, when the pH is higher than 7, the viscosity of the coating liquid tends to increase and the stability with time may decrease.

The coating liquid may contain pigments other than alumina hydrate, such as calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titania, zinc oxide, zinc carbonate, aluminum silicate, silicic acid, and silicic acid. If necessary, one or more of inorganic pigments such as sodium, magnesium silicate, calcium silicate, and silica, and organic pigments such as various plastic pigments and urea resin pigments can be added. The amount of addition of these pigments is within a range that does not impair the effect of fixing the ink dye, coloring, etc. by using alumina hydrate, for example, alumina hydrate 100
It is preferably 10 parts by weight or less with respect to parts by weight.

Further, a water-soluble polymer can be added to the coating liquid as needed. Examples of the water-soluble polymer include polyvinyl alcohol or modified products thereof (cation modified products, anion modified products, silanol modified products, etc.), starch or modified products thereof (oxides, etherified products), gelatin or modified products thereof. Casein or its modified form, carboxymethyl cellulose, gum arabic,
One or more of cellulose derivatives such as hydroxyethyl cellulose and hydroxypropylmethyl cellulose, polyvinylpyrrolidone, polymers of maleic anhydride or copolymers with other monomers, and acrylic acid ester copolymers can be used. These water-soluble polymers are also used in a range that does not impair the effect of using the anionic resin emulsion, and for example, used in a range of 3 to 40 parts by weight with respect to 100 parts by weight of the solid content in the anionic resin emulsion. Preferably. If the amount is more than this range, problems such as deterioration of ink absorbency and water resistance and occurrence of beading may occur.

The coating liquid may further contain a dispersant, a thickener, a pH adjuster, a lubricant, a fluidity modifier, a surfactant, a defoaming agent, and a water-proofing agent so long as the object of the present invention is not impaired. Agent, foam suppressant,
It is also possible to add a release agent, an antifungal agent and the like.

The coating of the coating liquid on the substrate is carried out, for example, by a blade coating method, an air knife coating method, a roll coating method, a flash coating method, a gravure coating method, a kiss coating method, a die coating method, an extrusion method, a slide hopper. (Slide beat) method, curtain coating method, spray method and the like can be used.

The coating amount of the coating liquid on the substrate is the dry solid content.
By conversion, the lower limit is 0.5 g / m ², Preferably 5g
/ M²Degree, the upper limit is 60g / m², Preferably 45
g / m²It is considered as a degree. The layer thickness of the ink receiving layer is
It can be selected appropriately according to the desired application, but it is better
In order to obtain good ink absorbency, 15 μm or more, preferably
Is 20 μm or more, but the production efficiency of the ink receiving layer
It is good to set the upper limit in consideration. In this way,
In the light, the layer thickness of the ink receiving layer using alumina hydrate
Even if it is thinner than the conventional one of about 15 to 20 μm
Good ink absorbency can be secured. Layer thickness of ink receiving layer
Since it has become possible to reduce the
To solve the problem of production efficiency
Significant improvement in productivity such as adoption of coating speed
Can be achieved.

An ink receiving layer is obtained by subjecting the coating layer provided on the substrate to a drying treatment by heating as necessary. By the drying treatment, the aqueous medium (dispersion medium) evaporates, and film formation occurs due to the fusion in the state where the alumina hydrate particles of the resin particles are incorporated. The conditions for the drying treatment can be appropriately determined according to the composition of the coating liquid used. In the present invention, the layer thickness of the ink receiving layer can be made thinner than the conventional one, and in that case, the productivity can be improved by shortening the drying time.

The ink receiving layer thus obtained contains at least alumina hydrate particles and a binder resin, and maintains the advantages of using alumina hydrate.
It also has good ink absorbency and water resistance, and has high productivity.

In the case of using the coating liquid in which the alumina hydrate and the anionic resin emulsion are mixed while suppressing the fluctuation of the pH value as described above, the improvement in the ink absorbability is observed. Alumina hydrate particles among them, or the aggregation of anionic resin particles each other is appropriately inhibited to form these effective dispersion state, the alumina hydrate particles are appropriately dispersed in the binder resin, and It is considered that fine pores that improve ink absorbency are also formed.

FIG. 1 schematically shows the film forming process.
Is. That is, since the resin particles contained in the emulsion are anionic, they are moderately attracted by electrical interaction with the cationic alumina hydrate, and the binder resins are fused around the alumina hydrate particles to form a continuous layer. In addition, the alumina hydrate particles are bound to the ink receiving layer by the fused binder resin, and a porous structure having better ink absorbability is obtained. For example, when a cationic or nonionic resin emulsion is used, the cationic resin emulsion electrically repels the same cationic alumina hydrate particles, and the nonionic resin emulsion uses an alumina hydrate. Since the affinity with the particles is weak, good electrical interaction does not occur between the alumina hydrate particles and the binder resin particles described above,
A good dispersed state cannot be obtained in these, and problems such as cracks are likely to occur. In the case of using these cationic or nonionic resin emulsions, if the content of the binder resin is increased in order to suppress the occurrence of cracks, there is a problem that the ink absorbency is lowered.

In general, as a substance to be used in combination with a cationic pigment such as alumina hydrate, there is little electric interaction with a cationic substance such as a cationic or nonionic substance in order to prevent the pigment from aggregating. Is usually selected. However, in the present invention, by adding the anionic resin emulsion to the cationic alumina hydrate while suppressing the fluctuation of pH, an appropriate affinity is generated between the dispersed particles, and cracks are generated. An ink-receptive layer with no generation and improved ink absorbency was obtained. This improvement in ink absorbency has the effect of suppressing the occurrence of beading, and at the same time, the productivity can be improved by reducing the layer thickness of the ink receiving layer.

The recording medium obtained by the method of the present invention has excellent properties for recording with ink, especially aqueous ink, and is suitable for inkjet recording, for example.

As the water-based ink, one composed mainly of a color material (dye or pigment) and a mixture of solvent components can be used. As the solvent component, water alone or a mixture of water and a water-soluble organic solvent is used. When a mixture of water and a water-soluble organic solvent is used as a solvent component, a mixture such that the water content in the ink is about 20 to 90% by weight is preferable. Further, as the dye, a water-soluble dye represented by, for example, a direct dye, an acid dye, a basic dye, a reactive dye, and an edible dye is preferable. A solubilizing agent may be added to the ink in order to improve the solubility of the coloring material in the solvent component, and in order to improve the properties of the ink, a viscosity adjusting agent, a surfactant may be added, if necessary. It is also possible to add various additives such as a surface tension adjusting agent, a pH adjusting agent, a specific resistance adjusting agent and a storage stabilizer.

There are no particular restrictions on the recording device used for inkjet recording with a water-based ink on the recording medium, and various inkjet recording devices can be used. For example, as disclosed in Japanese Patent Laid-Open No. 54-59936, heat energy is applied to ink in a recording head in accordance with a recording signal to cause the ink to fly as small droplets from an ejection port and attach it to a recording medium. The ink jet recording method for performing the recording can be suitably applied. Since the recording medium of the present invention has good ink absorbability, it can exhibit good recording characteristics even in full-color inkjet recording using cyan, magenta, yellow and black inks.

[0058]

EXAMPLES The present invention will now be described in more detail with reference to Examples and the like, but the present invention is not limited thereto. Reference Example 1 (Production of Alumina Hydrate) Aluminum dodoxide produced according to the method described in US Pat. No. 4,242,271 is hydrolyzed according to the method described in US Pat. No. 4,202,870 to give an alumina slurry. Obtained. This alumina slurry was diluted with water until the alumina hydrate solid content was 7.9% by weight. PH of this dilution
Was measured to be 9.5. After adjusting the pH of this diluted solution to 6.6 with a 3.9% nitric acid solution, it was aged by heating in an autoclave at 125 ° C. for 6 hours to give an aged solution of 75
It was subjected to spray drying at 0 ° C to obtain particulate alumina hydrate particles.

The BET specific surface area of the alumina hydrate particles was 220.2 m ² / g and the pore volume was 0.68 ml / g. In addition, the pore volume is measured by using a device (Kantachrome Co., Ltd., Autosorb I) for measuring the amount of nitrogen adsorbed and desorbed after degassing the particles at 120 ° C. for 24 hours, and measuring the BET ratio. The surface area is determined by the method of Brunauer et al. (J. Am. Chem. Soc., 60, 309, 19).
38).

Example 1 The alumina hydrate obtained in Reference Example 1 was dispersed in ion-exchanged water so that the solid content was 20% by weight, and a dispersion liquid (pH
4.0) was obtained. Trade name: Cybinol AS-550 (manufactured by Saiden Chemical Co., Ltd., solid content 54.7% by weight, minimum film forming temperature 3) which is an aqueous dispersion of this alumina hydrate and an anionic polyvinyl acetate resin emulsion. ℃, glass transition temperature of resin 17 ℃, dispersed resin particle size 0.35μ
m) and the weight ratio of the solid content are (solid content of the aqueous dispersion of alumina hydrate) :( solid content of Cybinol AS-550) = 6: 1, and the mixture is stirred and applied. A liquid was obtained.

A white polyester film (manufactured by Toray Industries, Inc., Lumirror X-21, thickness 100 μm) was applied to this coating solution.
A die coater was used to apply a dry film thickness of 20 μm at a coating speed of 25 m / min, followed by drying at 110 ° C. to form an ink receiving layer, to obtain a recording medium of the present invention.

16 / mm with respect to the obtained recording medium
The recording head with 128 ejection ports arranged at a density of
Ink jet recording is performed using an ink having the following composition by using an ink jet recording apparatus having four colors of (yellow), M (magenta), C (cyan), and B (black). Generation and water resistance were evaluated.

[0063]

[Table 1] 1) The following dyes were used individually.

Y: C.I. I. Direct Yellow 86 M: C.I. I. Acid Red 35 C: C.I. I. Direct Blue 35 Bk: C.I. I. Food Black 2 (1) Ink absorbency The ink absorbency was examined by touching the recording part with a finger immediately after solid-color solid printing and multi-color solid printing were performed on the surface of the recording medium on which the ink receiving layer was formed with the above-described four color inks. . As a result, the ink did not adhere to the finger even in the multi-color solid print portion (three times the amount of ink attached to the single-color print portion), and the ink absorbability was good. (2) Beading After the printing was performed in the same manner as above, the occurrence of beading was visually observed, and no occurrence of beading was observed and a good printed portion was obtained. (3) Water resistance Single-color solid printing was performed using the above-described four color inks, left for 24 hours, immersed in running water for 3 minutes, and then naturally dried to examine the state of the ink receiving layer. As a result, the results such as breakage, peeling and detachment due to dissolution of the ink receiving layer were not observed. Furthermore, when the water resistance of the recorded image was calculated, the water resistance of each solid print portion was 95%, and good water resistance was obtained.

Comparative Example 1 As an anionic acrylic resin emulsion, trade name: Cybinol EK-11-5 (manufactured by Saiden Chemical Co., Ltd.,
Solid content 30.0% by weight, minimum film forming temperature 25 ° C, glass transition temperature of dispersed resin -14 ° C, particle diameter 0.16 μm,
A coating liquid was prepared in the same manner as in Example 1 except that pH 9.4) was used. However, the coating liquid gelated immediately after mixing with the aqueous dispersion of the alumina hydrate, and was not suitable for coating.

Comparative Example 2 Nonionic polyvinylidene chloride resin emulsion, trade name: Saran Latec L-521 (Asahi Kasei Corp.)
Manufactured by the company, solid content 50.0% by weight, minimum film forming temperature 17-
A recording medium was prepared in the same manner as in Example 1 except that 23 ° C., particle diameter 0.21 μm, pH 2.0) was used instead of the anionic resin emulsion.

The ink receiving layer of the obtained recording medium was markedly cracked, and could not be practically used as a product.

Comparative Example 3 Cationic acrylic resin emulsion, trade name: Boncoat SFC-55 (manufactured by Dainippon Ink and Chemicals, Inc., solid content 29.6% by weight, minimum film forming temperature 0 ° C. or lower, Example 1 except that a particle size of 0.2-0.3 μm, pH 4.5) is used instead of the anionic resin emulsion.
A recording medium was prepared in the same manner as in. The obtained recording medium was not able to withstand practical use because the ink receiving layer was significantly cracked.

[0069]

According to the present invention, while maintaining the various advantages of using alumina hydrate, beading is less likely to occur due to excellent ink absorbency, and further excellent water resistance and stable quality are obtained. Thus, it is possible to provide a recording medium that can be manufactured efficiently.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining a process of forming an ink receiving layer in the production of a recording medium of the present invention, in which alumina hydrate particles and anionic resin particles are mixed in an aqueous dispersion medium. The state before being dried and the state where the resin particles are fused to form a film by heating and drying are shown.

[Explanation of symbols]

 1 Alumina hydrate particles 2 Anionic resin particles 3 Resin layer 4 Pore generated by partial inhibition of film formation

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hiroyuki Sugada 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (16)

[Claims] 1. A recording medium comprising an ink-receiving layer provided on a substrate, wherein the ink-receiving layer comprises a coating liquid mainly composed of a particulate alumina hydrate and an anionic resin emulsion on the substrate. A recording medium, which is obtained by coating and drying. 2. The recording medium according to claim 1, wherein the minimum film-forming temperature of the anionic resin emulsion is in the range of 0 to 50 ° C. 3. The glass transition temperature of the resin constituting the dispersed resin particles in the anionic resin emulsion is 0 to 90.
The recording medium according to claim 1, which is in the range of ° C. 4. The recording medium according to claim 1, wherein the particle diameter of the dispersed resin particles in the anionic resin emulsion is in the range of 0.07 to 0.7 μm. 5. An image, characterized in that a small ink droplet is ejected from an ejection port of a recording head in accordance with a recording signal and adhered to the recording medium according to any one of claims 1 to 4 to form an image. Forming method. 6. The image forming method according to claim 5, wherein thermal energy is applied to the ink to eject a small droplet of the ink from the ejection port of the recording head. 7. A droplet of cyan, magenta, yellow, and black ink is ejected from an ejection port of a recording head in accordance with a recording signal and is attached to the recording medium according to claim 1 to form an image. An image forming method characterized by forming. 8. The image forming method according to claim 7, wherein thermal energy is applied to the ink to eject a small droplet of the ink from the ejection port of the recording head. 9. A step of applying a coating solution containing an alumina hydrate and an anionic resin emulsion onto a substrate to obtain a coating layer, and a step of drying the coating layer to form an ink receiving layer. And a pH value (pH _A ) given by the alumina hydrate in the same amount of ion-exchanged water as the coating liquid and a pH value (pH _E ) of the anionic resin emulsion. ) And pH _A −pH _E ≦ ± 2
A method for manufacturing a recording medium, which satisfies the following relationship. 10. The method for producing a recording medium according to claim 9, wherein the minimum film-forming temperature of the anionic resin emulsion is in the range of 0 to 50 ° C. 11. The glass transition temperature of the resin constituting the dispersed resin particles in the anionic resin emulsion is 0-9.
The method for producing a recording medium according to claim 10, wherein the temperature is in the range of 0 ° C. 12. The method for producing a recording medium according to claim 10, wherein the particle diameter of the dispersed resin particles in the anionic resin emulsion is in the range of 0.07 to 0.7 μm. 13. A step of applying a coating liquid, which is a mixture of at least a dispersion of an alumina hydrate and an anionic resin emulsion, onto a substrate to obtain a coating layer, and drying the coating layer. A method for producing a recording medium, which comprises a step of forming an ink receiving layer, the pH value (pH _A ) of the aqueous dispersion of alumina hydrate and the pH value (pH _E ) of the anionic resin emulsion. Satisfying the relationship of pH _A −pH _E ≦ ± 2, the method for producing a recording medium. 14. The method for producing a recording medium according to claim 13, wherein the minimum film forming temperature of the anionic resin emulsion is in the range of 0 to 50 ° C. 15. The glass transition temperature of the resin constituting the dispersion resin resin in the anionic resin emulsion is 0-9.
The method for producing a recording medium according to claim 13 or 14, which is in the range of 0 ° C. 16. The method for producing a recording medium according to claim 13, wherein the dispersed resin particles in the anionic resin emulsion have a particle size in the range of 0.07 to 0.7 μm.