JP2001246840A - Medium to be recorded, manufacturing method therefor, and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excellent medium to be recorded, which does not impair the natural texture intrinsic to a base paper, at the same time, has a pencil writing property and an excellent ink absorbing property without largely depending on the absorption of the base paper, a quicker ink absorption speed, from which an image with a high image density, a clear color tone and a high resolution, can be obtained. SOLUTION: In the medium to be recorded, which is produced by forming an ink accepting layer having an inorganic pigment and a binder on a base material mainly made of pulp fibers, the coating build-up of the ink accepting layer is 1 to 10 g/m2. At the same time, the pore distribution of the medium to be recorded has the maximum value of the pore radius of a base material and the maximum value of the pore radius in the ink accepting layer. At the same time, the maximum value of the pore radius in the ink accepting layer lies within the range of 8 to 50 nm, in the manufacturing method of the medium to be recorded and an image forming method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for color recording using an aqueous ink, particularly for color recording using an ink jet recording system, and has a paper texture of pulp fibers and an ink absorbing property. The present invention relates to a recording medium having good pencil writing properties, a method for manufacturing the same, and an image forming method using the recording medium.

[0002]

2. Description of the Related Art An ink jet recording method is a method of recording images and characters by flying fine droplets of ink and attaching them to a recording medium (paper or the like) by various operating principles. Features include noise, easy multi-coloring, high flexibility of recording patterns, and no need for development and fixing.
It is rapidly spreading in various applications. Furthermore, according to the multi-color ink jet recording method, it is possible to form a multi-color image comparable to multi-color printing by a conventional plate-making method or printing by a color photographic method, and furthermore, the number of copies to be made When the number is small, a printed matter can be obtained at a lower cost than ordinary multicolor printing or printing, and is being widely applied to the field of full-color image recording.

In the above-mentioned ink jet recording system,
Conventionally, with the demand for improvement of recording characteristics such as high-speed recording, high-definition and full-color recording, improvements have been made to ink jet recording apparatuses and recording methods, and at the same time, for recording media to be used. However, advanced characteristics are required. In the ink jet recording system, ink containing a large amount of water or a water-based solvent such as a mixture of water and an organic solvent is used because it is necessary to eject ink droplets from a nozzle toward a recording medium at high speed. . Therefore, in order to obtain a recorded image with a high color density, a large amount of ink must be used. In addition, since the ink droplets are continuously ejected, a beading phenomenon in which the dots of the ink are joined may occur, and the image may be disturbed. To prevent this beading phenomenon, the recording medium to be used is required to have a large ink absorption amount and a high ink absorption speed.

In order to solve such a demand, conventionally,
Various types of recording media have been proposed. For example, as the form of the ink jet recording sheet, a plain paper type represented by a high quality paper or a bond paper, a paper such as a high quality paper, a support such as a synthetic paper or a synthetic resin film (hereinafter referred to as a base paper or a base material). This is roughly classified into a coating type in which an ink receiving layer (coating layer) is provided on the surface. Further, coating type, according to the coating amount, 1 to 10 g / m ² as low coating weight type, 10 to 20 g / m ² about intercoat coating amount type, 20 g / m ² or more high coating weight Classified into types.

[0005] An ink jet recording sheet having a thick ink receiving layer of a medium coating amount type or more can form a high-definition and clear image in ink jet recording, but the thick ink receiving layer causes the texture and handleability of the base paper. However, there is a drawback that is deteriorated. Furthermore, there is a problem that pencil writing properties cannot be obtained. For this reason, there is a demand for the development of a low coating amount type recording medium that has good texture and handleability, has good pencil writing properties, and can form a high-definition and clear image.

On the other hand, in the case of a recording medium of a low coating amount type having a thin ink receiving layer, it is difficult to absorb all the ink only by the ink receiving layer. Need to be absorbed. For example, JP-B-3-26665, JP-A-59-38087, and JP-A-59-9516 disclose examples in which a base paper having a relatively low degree of Stight sizing is used. . In the case of using a substrate with a low degree of Stockigt size,
By utilizing the high absorbency of the ink of the base material, the so-called beading phenomenon that the ink overflows and bleeds, and further, the ink aggregates on the surface and becomes uneven, can be prevented.

However, on the other hand, in the recording medium of the low coating amount type shown in the above-mentioned conventional example, the ink penetrates deeply into the inside of the base material, and the print density of the recorded matter does not increase. Cause problems. That is, in the case of a recording medium of a conventionally known low coating amount type, by using a base paper having a relatively low size degree, it largely depends on the ink absorbency of the base paper itself, The amount of coating is small, and the coating liquid may not be applied uniformly to the entangled irregularities of the pulp of the base paper. Exposure of pulp fibers on the surface of the medium was sometimes noticeable. When an image is formed on a recording medium having such a configuration, particularly when an aqueous ink is used, the ink is unevenly diffused along the coarse pulp fiber, and a whisker ( Feathering), resulting in a dot having extremely low roundness.

In Japanese Patent Publication No. 63-22997, an ink receiving layer is provided on the surface of a support, and one peak of a pore distribution curve of the uppermost layer is in a range of 0.2 μm to 10 μm. An example of adjusting the peak balance is given. In this case, a feature is that a portion having a large pore radius, that is, a pore of 0.2 μm to 10 μm is always formed in the uppermost layer. Thereby, a high ink absorption capacity (ink absorption speed) is obtained mainly by the two-layer structure. However, with such a configuration, the original characteristics of the base paper, that is, the feeling, the color, and the like cannot be sufficiently obtained. Further, since the gap structure of the base paper itself is not sufficiently utilized, there may be a case where sufficient ink absorption characteristics cannot be obtained depending on the difference in the degree of Stigecht size and surface shape of the base paper.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, and to improve the pencil writing performance without impairing the natural texture inherent in the base paper. It has excellent ink absorbency without greatly depending on the absorption of the base paper, has a high ink absorption speed, and is also suitable for high-speed printing with a small number of print passes, and has a high image density. Another object of the present invention is to provide an excellent recording medium capable of obtaining a high-resolution image with a clear color tone.
Furthermore, another object of the present invention is to provide a recording medium having excellent characteristics when various base papers (various degrees of stoichiometry, surface shapes, etc.) are used.

[0010]

The above objects are achieved by the present invention described below. That is, the present invention provides a recording medium in which an ink receiving layer having an inorganic pigment and a binder is formed on a base material mainly composed of pulp fibers.
The coating amount of the ink receiving layer is 1 to 10 g / m ² ,
Further, the pore distribution of the recording medium has the maximum value of the pore radius of the base material and the maximum value of the pore radius of the ink receiving layer, and the maximum value of the pore radius of the ink receiving layer. Value is 8n
a recording medium, a method for manufacturing the recording medium, and an image forming method, wherein the recording medium is in the range of m to 50 nm.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to preferred embodiments. FIG. 1 is a schematic sectional view showing an example of the recording medium of the present invention. This recording medium 100
Is formed by forming an ink receiving layer 102 on a base material 101. As the base material 101, generally available papers mainly composed of pulp fibers can be used, and are not limited at all. For example, a papermaking raw material mainly composed of pulp fibers and a filler is prepared by a known method. It can be formed by papermaking. The fibrous pulp can be used without any particular limitation as long as it is used in ordinary paper production. For example, chemical pulp represented by LBKP, NBKP and the like,
Mechanical pulp, recycled paper pulp, non-wood pulp, or a mixture of two or more thereof can be used.

For the papermaking of the base paper, there can be used, for example, an ordinary method of making a paper mainly using fibrous pulp and filler, and using a sizing agent and a papermaking auxiliary agent as required. As the filler, for example, calcium carbonate, kaolin, talc, titanium dioxide and the like can be used. Among them, kaolin is particularly preferable. As sizing agents, rosin size, alkyl ketene dimer,
Alkenyl succinic anhydride, petroleum resin size, epichlorohydrin, acrylamide and the like can be used. The gap structure of the paper itself made mainly of these pulp fibers is effective when used as a base material of a recording medium for inkjet.

The gap structure of paper suitable as a substrate of the recording medium of the present invention is preferably such that the maximum value of the pore radius in the pore distribution of the substrate is in the range of 500 nm to 10,000 nm. Furthermore, from 1,000 nm to 5,000
It is preferable to use one in the range of 0 nm. The gap structure is
It can be adjusted by papermaking conditions, pulp type, blending ratio of each pulp, and the like. On the other hand, when the pore radius of the base material is too small, the ink solvent component may not be sufficiently taken up. On the other hand, if the pore radius of the base material is too large, it may be difficult to hold the ink receiving layer on the surface of the base material, and variations in print characteristics, partial overflow, bleeding, decrease in print density, etc. May occur.

The substrate of the present invention is not particularly limited with respect to the degree of Stekigt sizing, but is preferably adjusted to a range of 10 to 400 seconds in terms of a basis weight of 127 g / m ² . If the Stöckigt sizing degree is higher than this range, the ink absorbency may be insufficient. vice versa,
If the degree of size is low, feathering or a decrease in the density of a printed portion may occur, and the quality may be insufficient. or,
As a base material, paper was partially dyed with a dye, pressed, embossed, and machined in order to impart various colors and textures to the paper, giving it a distinctive color tone, gloss, and appearance. Design paper or pattern paper may be used.

In this recording medium, as shown in FIG.
An ink receiving layer is provided on the base paper 101 as described above. The ink receiving layer 102 is formed as a microporous thin film formed by a combination of an inorganic pigment and a binder.
When recording is performed on the recording medium 100 of the present invention having such a configuration, the solvent content of the ink firstly
It is taken into the voids of the ink receiving layer 102, reaches the base paper 101 by capillary action, and is absorbed therein. At this time, since the ink receiving layer 102 is a microporous thin film,
Since the coloring material of the ink is dyed and adsorbed on the surface thereof, and the solvent component of the next ink can be quickly transferred to the base paper side, bleeding hardly occurs.

Here, in the recording medium of the present invention, as shown in FIG. 2, the pore size of the ink receiving layer 102 is determined by measuring the pore distribution curve of the recording medium.
A peak B appears in addition to the peak A due to the voids of the base paper, and this peak B is caused by the pores of the ink receiving layer.
It is. In the recording medium of the present invention, the peak B has a maximum value in the range of 8 nm to 50 nm. If the peak B of the pores due to the voids in the ink receiving layer 102 is smaller than 8 nm, the ink absorption speed decreases, and in high-speed printing with a small number of passes, the ink absorption cannot catch up and the ink overflows. Occur,
Non-uniformity of absorption occurs, and uneven stripes occur. On the other hand, if the peak B is larger than 50 nm, a dense microporous film (ink receiving layer) is not formed, so that when an image is formed, dot spread and ink bleeding occur. . In this case, the transparency of the coating film (ink receiving layer) is also reduced, so that a clear image cannot be obtained. In order for the ink receiving layer 102 to have sufficient ink absorbency and transparency, in the distribution of the pore distribution curve of the recording medium, in particular, the peak B falls within the pore range of 10 nm to 30 nm. It is more preferable to have such a configuration.

With respect to the ink absorption capacity (pore volume) in the pores formed in the ink receiving layer, the types and mixing ratios of the inorganic pigments and binders constituting the ink receiving layer, and the film thickness of the ink receiving layer It is possible to adjust appropriately by changing the above. In particular, in order to once receive the solvent component of the ink applied to the recording medium, and then to promptly transfer the solvent to a base material mainly composed of pulp fibers, the above-described pore radius is preferably 8 nm to 50 nm. Has a total pore volume of at least 0.004 cm ³ / g,
It is preferably at least 5 cm ³ / g, more preferably the total pore volume is at least 0.01 cm ³ / g. The upper limit is desirably adjusted within a range in which the strength and transparency of the ink receiving layer and the feeling of the substrate can be utilized. Specifically, it is appropriate that the density is 0.1 cm ³ / g or less. By increasing the pore radius and the pore volume on the base material side, ink transfer in the up and down direction may be suitably performed. become.

Further, when the ratio of the pore volume of the base paper to the pore volume of the ink receiving layer is smaller than 1/10, the transfer of ink in the vertical direction is promoted. The preferred ratio is 1/1
0 or less, more preferably 1/20 to 1/50.
The absorption capacity (pore volume) can be determined by subtracting the pore distribution curve after coating from the pore distribution curve in the base paper before coating. In addition, the void in the present invention is defined as two directions such as up and down and left and right directions in the ink receiving layer.
It is formed with a pore structure connected in three-dimensional and three-dimensional directions, whereby the solvent component in the ink can quickly pass through the pores and is connected to the base paper. Incidentally, in the present invention, the pore distribution measurement of the ink receiving layer 102 described above,
It was measured by the mercury intrusion method.

In the recording medium of the present invention, in order to form the above-mentioned pore structure so that the ink receiving layer has a sufficient ink absorbency, the type of inorganic pigment constituting the ink receiving layer is required. The kind of the binder, the mixing ratio thereof, the drying conditions at the time of film formation, the film thickness, and the like may be appropriately selected, and as a result, a sufficient absorption and absorption of the solvent in the ink can be obtained.

In the recording medium of the present invention, the ink receiving layer 102 constituted as described above has a coverage of 90% or more with respect to the substrate surface, and more preferably, the surface of the substrate is completely exposed. It is preferably formed in a completely uncovered state. By doing so, the coloring material of the ink can be surely dyed and adsorbed in the ink receiving layer and on the surface, so that a high coloring property can be obtained uniformly and a high image density can be obtained. . Furthermore, if the ink receiving layer is formed at the above-described coverage, the portion where the base paper is exposed is reduced, so that the entire recording medium becomes uniform with respect to absorptivity, and partial overflow occurs. The occurrence of a beading phenomenon in which ink aggregates on the surface to connect dots can also be suppressed.

Further, when the ink receiving layer is sufficiently covered, fine cracks may be formed on the surface of the ink receiving layer. Here, the minute crack means a small crack formed on the surface of the ink receiving layer, and its shape and width are not particularly limited. The minute cracks supplement the ability of the ink to pass through the solvent, and further improve the ink absorption ability. Regarding the size of micro cracks,
Although not particularly specified, it is preferable that there is no large crack having a width of 200 μm or more. The formation of cracks is carried out by rapidly heating the coating liquid, then rapidly cooling, or adjusting the coating film. Furthermore, it can be formed by mixing resins having greatly different glass transition points or resins having different particle diameters, selecting types of inorganic pigments and binders, mixing ratios, and the like.

Regarding the thickness of the ink receiving layer, the recording medium of the present invention may have any thickness as long as it can be obtained by applying a small amount of 1 to 10 g / m ^2. In order to secure sufficient film strength and to obtain pencil writability, the film thickness is preferably 5 μm or less. Further, in order to improve the texture of the paper and the transparency of the film, the thickness is more preferably 2 μm or less.

The material for forming the ink receiving layer constituting the recording medium of the present invention will be described below. First, as the inorganic pigment used for forming the ink receiving layer, for example, silica, alumina, alumina hydrate, calcium carbonate, zeolite, diatomaceous earth, kaolin, clay, calcined clay,
Conventional talc, aluminum hydroxide, colloidal alumina, barium sulfate, titanium dioxide, zinc oxide, zinc carbonate, magnesium silicate, magnesium carbonate, hydrotalcite, etc., which are conventionally used in the coating layer of general coated paper Can be used. In the present invention, these inorganic pigments can be used alone or in an appropriate mixture of two or more. Particularly preferred pigments are
It is preferable to use silica or alumina hydrate so that the ink receiving layer has high transparency and absorbency.

In this case, as the silica, natural silica, synthetic silica, amorphous silica and the like, and chemically modified silica compounds can be used, but silica having a positive charge is particularly preferable. In addition, since alumina hydrate has a positive charge, the dye in the ink is well fixed, a high gloss, a good color image is obtained, and further, compared to the ink receiving layer using other pigments. Because it has low haze and high transparency, it is more preferable as a pigment used in the ink receiving layer.

The inorganic pigment used in the present invention is composed of the above-mentioned materials, and it is preferable to use a pigment having porosity in its particles. In order to obtain the pore radius of the ink receiving layer desired in the present invention described above, and further the pore volume, the BET specific surface area is 10 to 10.
It is preferable to use the inorganic pigments in the range of 500m ² / g. If the BET specific surface area deviates significantly from the above range, it may be difficult to obtain a desired maximum value of the pore radius in the pore distribution of the recording medium.
Furthermore, as an inorganic pigment, the BET specific surface area is 40 to 25.
It is more preferable to use one having 0 m ² / g. In the present invention, the pore volume of the inorganic pigment is from 0.1 to 3.
It is preferable to use one having a range of 0 cm ³ / g. Further, those in the range of 0.3 to 1.0 cm ³ / g are more preferable.

When forming the ink receiving layer of the recording medium of the present invention, the binder used in combination with the above-mentioned inorganic pigment may be a water-soluble, water-dispersible, water / organic solvent mixed resin or the like. It will not be done. For example, polyvinyl alcohol or a modified product thereof (cation modified, anionic modified, silanol modified), starch or a modified product thereof,
Gelatin or a modified product thereof, cellulose such as carboxymethylcellulose, gum arabic, hydroxyethylcellulose, cellulose derivatives such as hydroxypropylmethylcellulose, SBR latex, NBR latex,
Conjugated diene-based copolymer latex such as methyl methacrylate-butadiene copolymer, functional group-modified polymer latex, vinyl-based copolymer latex such as ethylene-vinyl acetate copolymer, polyvinylpyrrolidone, maleic anhydride,
Alternatively, it is preferable to use a copolymer thereof, an acrylate copolymer, or the like. These binders can be used alone or in combination of two or more. Among these, in order to form desired pores in the ink receiving layer, it is preferable to use a latex / emulsion type, which does not easily cause binder migration when heated and dried.

Further, in order to obtain sufficient pores in the ink receiving layer, it is preferable to further suppress binder migration, and for that purpose, it is effective to use a binder having a high glass transition point. For example, it is effective to use an emulsion-type resin having a glass transition point in the range of 20C to 120C as a binder.
That is, if the glass transition point is too low, it may be difficult to suppress binder migration with ordinary emulsion particles, and if it is too high, the film formability may be poor.

In the present invention, it is more effective to use a binder having a thermosensitive gelling property as the binder. That is, when forming the ink receiving layer, the occurrence of binder migration is effectively suppressed by using a binder containing a component whose hydrophilicity and hydrophobicity change reversibly at a certain temperature as a boundary. In this case, the glass transition point of the binder does not require a particularly high temperature, and for example, a binder having a temperature in the range of -20 ° C to 60 ° C is preferably used.

In the case of forming the ink receiving layer, more optimal pores can be obtained by forming a film in a state where the inorganic particles and the binder are weakly aggregated as described above. Specific examples thereof include using inorganic pigments and binders, each of which has opposite ionic properties, to form weak aggregation in a coating liquid composed of these, or to weakly aggregate after coating. This creates an optimal pore. On the other hand, it is difficult to obtain optimal pores with a coating liquid having good dispersibility. As a method of controlling the coating liquid to a state of weak aggregation, for example, a combination of a strong cationic inorganic pigment and a weak anionic binder, a combination of a weak cationic inorganic pigment and a strong anionic binder and the like Although some methods are conceivable, it is also possible to control the mixing ratio by mixing the inorganic pigment and the binder and adding a cationic substance.
By forming a film using the coating liquid in the weakly agglomerated state, the ink receiving layer having the gap structure desired in the present invention can be obtained by controlling the pore properties and the agglomerated state of the inorganic pigment itself. On the other hand, when a coating liquid that has been strongly agglomerated is used, not only uniform coating becomes difficult, but also problems such as uneven absorption and reduced transparency occur.

When the coating liquid for forming the ink receiving layer is prepared, the mixing ratio of the inorganic pigment to the binder as described above is determined with respect to the ink absorbing property and the film strength of the obtained ink receiving layer. In consideration of transparency and the like, in the present invention, the solid content ratio of the inorganic pigment: binder = 2: 1 to 1
A range of 10: 1 is preferred. When the amount of the binder is larger than this range, that is, 2: 1, a sufficient gap structure may not be obtained. When the amount of the binder is smaller than 10: 1, the film strength is not sufficient. Similarly, since the number of bonds between the binder and the inorganic pigment is reduced, similarly, it is difficult to obtain pores having the maximum value of the ink receiving layer desired in the present invention. Further, inorganic pigment: binder = 3: 1 to 7:
It is more preferable to use in the range of 1.

In forming the ink receiving layer, when a cationic substance is added to the material for forming the ink receiving layer to control the aggregation state, a cationic low molecular substance or a cationic high molecular substance as described below is used. Molecular substances and the like can be used. Specifically, the cationic low molecular weight substance has a molecular weight of 1,000 or less, and is a primary, secondary or tertiary amine salt such as a hydrochloride such as laurylamine, cocoamine, stearinamine or rosinamine, or an acetate. Compounds of the quaternary ammonium salt type such as lauryltrimethylammonium chloride, lauryldimethylbenzylammonium chloride, benzyltributylammonium chloride and benzalkonium chloride; Pyridinium salt compounds such as cetylpyridinium chloride and cetylpyridinium bromide; 2-heptadecenyl Imidazoline-type cationic compounds such as -hydroxyethylimidazoline; ethylene oxide adducts of higher alkylamines such as dihydroxyethylstearinamine;
Also, metal compounds can be used. Specific examples include aluminum lactate, basic polyaluminum hydroxide, aluminum chloride, sodium aluminate, and aluminum acrylate.

As the cationic polymer, a molecular weight of 2,0
00 or more, for example, polyallylamine or its hydrochloride, polyamine sulfone or its hydrochloride, polyvinylamine or its hydrochloride, chitosan or its acetate, and of course, those limited to these. is not. Further, it is not limited to the hydrochloride type and the acetate type. Similarly, a part of the nonionic polymer may be cationized. Specifically, a copolymer of vinylpyrrolidone and an aminoalkyl alkylate quaternary salt,
Copolymers of acrylamide and aminomethylacrylamide quaternary salt can be exemplified, but it goes without saying that the invention is not limited to these compounds.

Also, of course, the molecular weight is 1,000.
Those having a range of ~ 2,000 can also be used.
A mixed system of those mentioned above may be used. The above-mentioned cationic substance is preferably soluble in water or dissolved in a mixture of water and an organic solvent, but may be a dispersion such as a latex or an emulsion. The amount of addition is not less than the amount that insolubilizes the coloring material component of the ink and can exhibit the effect of water resistance, causes abnormal aggregation with inorganic pigments and binders, and increases the viscosity and does not cause gelation. Is preferred. Specifically, it is preferable to add 0.1 to 6 g / m ² to the ink receiving layer of the recording medium.

Further, a penetration aid may be added to the ink receiving layer in order to impart ink permeability to the ink receiving layer. Specific examples of the penetration aid include a surfactant. Examples of the surfactant include anionic surfactants such as carboxylate, sulfonate, sulfate, and phosphate, aliphatic amine salts, aliphatic quaternary ammonium salts, and aromatic quaternary ammonium salts. And cationic surfactants such as heterocyclic quaternary ammonium salts, ether type such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene polyoxypropylene block polymer, polyoxyethylene glycerin fatty acid ester, polyoxy Ether ester type such as ethylene sorbitan fatty acid ester, ester type polyoxyethylene fatty acid amide such as polyethylene glycol fatty acid ester, sorbitan fatty acid ester and sucrose fatty acid ester, and nitrogen-containing type such as polyoxyethylene alkylamine. And nonionic surface active agents, betaine, aminocarboxylate, amphoteric surfactants such as imidazoline derivatives. Further, a penetration aid other than the surfactant may be used.

In the recording medium of the present invention, a coating liquid prepared by adding an inorganic pigment and a binder as described above, a cationic substance to be added as required, and a penetration aid, etc. By coating on a base material, an ink receiving layer having desired pores can be formed. The coating liquid used at this time is obtained by mixing the above-mentioned constituent components in a desired ratio, and uniformly dispersing and dissolving in water by a usual method. As a dispersion method, for example,
It is preferable to use a dispersing machine such as a ball mill, an attritor, a sand mill, a homomixer, a microfluidizer (manufactured by Microfluidics), and a nanomizer (manufactured by Nanomizer). The viscosity, pH, dispersibility, and the like are important as the physical properties of the coating solution used. For example, the viscosity is preferably adjusted appropriately according to the coating method used. Specifically, for example, 3 cps to 500 cps
It is preferable to use a coating liquid whose viscosity has been adjusted to the range described above.
Further, the pH is preferably adjusted to a range of 3 to 7. At this time, the liquid pH may be measured by a method specified in JIS Z8802.

Further, in order to obtain uniform coating characteristics and transparency, it is necessary to ensure more sufficient dispersibility and storage stability of the coating liquid. Therefore, in the coating liquid,
As long as the object of the present invention is not impaired, if necessary, for example, a dispersant, a thickener, a lubricant, a fluidity modifier, a surfactant, an antifoaming agent, a waterproofing agent, a foam inhibitor, a release agent And an antiseptic agent can be added.

Examples of the method of applying a coating solution having the above composition on a substrate include 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, and a die coating method. It can be performed by a method using a method, an extrusion method, a slide hopper method, a curtain coat method, a spray method, a size press method, a shim sizer coat method, a gate roll coat method, or the like. Above all, in the case of coating with a low coating amount and a small coating amount as performed in the present invention, the gravure coating method, size press method, shim sizer coating method, gate It is preferable to use a roll coating method, an improved method thereof, or the like. Further, after the coating, a calendering process such as a machine calender, a super calender, and a soft calender may be performed to finish. Further, in the present invention, a back coat layer may be further provided on the surface opposite to the surface on which the ink receptive coating layer formed by coating on the base material (support) is provided. . The composition of the material for forming the back coat layer may be the same as the composition of the material for forming the ink receiving layer, or may be a different composition.
The coating amount and the coating method are not limited at all.

Further, by subjecting the coating layer provided on the substrate as described above to a drying treatment by heating as necessary, an ink receiving layer desired in the present invention can be obtained. At this time, the drying treatment causes the aqueous medium (dispersion) to evaporate, and also causes the formation of a film by bonding by fusion of the binder. The conditions for the drying treatment can be appropriately selected according to the composition of the coating solution used. Drying may be performed by using a generally used hot air drying oven or infrared drying oven alone or in combination.

The image forming method of the present invention is characterized in that an image is formed by applying ink to the recording medium of the present invention as described above. Hereinafter, the image forming method of the present invention will be described. First, the ink used in the image forming method of the present invention will be described. As the ink, an ink mainly containing a coloring material such as a dye or a pigment, a water-soluble organic solvent and water can be used. Examples of the dyes that can be used include direct dyes, acid dyes, basic dyes, reactive dyes, and water-soluble dyes represented by food dyes. However, any dye may be used as long as it provides an image that satisfies the fixing property, color developing property, sharpness, stability, light resistance, and other required performances in combination with the above-described recording medium.
As the pigment, for example, inorganic pigments such as carbon black, various organic pigments, metal fine particles, metal oxides, metal compounds and the like can be used.

The water-soluble dyes mentioned above are generally used by dissolving them in water or a solvent comprising water and an organic solvent. In the present invention, the solvent component is preferably
A mixture of water and various water-soluble organic solvents is used.
The ink used in the image forming method of the present invention is preferably prepared so that the water content in the ink is in the range of 20 to 90% by weight.

Examples of the water-soluble organic solvent constituting the ink used in the image forming method of the present invention include alkyl alcohols having 1 to 4 carbon atoms such as methyl alcohol, etc.
Amides such as dimethylformamide, ketones or ketone alcohols such as acetone, ethers such as tetrahydrofuran, polyalkylene glycols such as polyethylene glycol, alkylene glycols in which an alkylene group such as ethylene glycol contains 2 to 6 carbon atoms And lower alkyl ethers of polyhydric alcohols such as glycerin and ethylene glycol methyl ether.

Among these many water-soluble organic solvents,
In the present invention, it is particularly preferable to use polyhydric alcohols such as diethylene glycol and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl ether and triethylene glycol monoethyl ether. Polyhydric alcohols are particularly preferable because they have a large effect as a lubricant for preventing nozzle clogging caused by 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, additives such as a viscosity modifier, a surfactant, a surface tension modifier, a pH regulator, and a specific resistance modifier may be added as needed to improve the ink properties.

In the image forming method of the present invention, it is preferable to use an ink jet recording method as a method of forming an image when the above-described ink is applied to the recording medium of the present invention for recording. . As a recording method, any method may be used as long as it can effectively remove ink from the nozzles and apply ink to the recording medium. In particular, in the present invention,
According to the method described in JP-A-59936, the ink subjected to the action of thermal energy causes a sudden change in volume, and the ink is applied to the recording medium by ejecting the ink from a nozzle by the action force due to the state change. The ink jet recording method can be used effectively.

According to the image forming method of the present invention for forming an image on the recording medium of the present invention using the above-described ink,
In particular, bleeding (boundary bleeding) in an image, beading that is caused by bleeding of ink droplets and leading to a bead shape, etc., such as a combination of solid printing with multicolor inks, due to the high absorption capacity of the recording medium, It is greatly reduced as compared with the conventional case. The recording medium of the present invention can be used not only for the above-mentioned ink-jet sheet but also for any recording method using a liquid ink at the time of recording. For example, a thermal transfer recording method, a photosensitive pressure-sensitive recording method, and the like can be given. Further, in recent years, it can be used as a recording system for heating and fixing an electrophotographic recording system toner widely used in copiers and printers, and as a proof for light printing.

[0046]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. (Example 1) The recording medium of the embodiment shown in FIG. 1 was produced as follows. First, paper having a basis weight of 127 g / m ^{2 was} prepared and used as the substrate 101 under the following papermaking conditions. The Stöckicht sizing degree was 120 seconds. The thickness of the support is 127 μm. When the surface was observed with a scanning microscope (Hitachi S-5000), FIG.
The pulp fibers shown in FIG. In addition, the mercury intrusion method (Autopore II manufactured by MICROMERITICS)
When the pore distribution of the base material was measured according to I9420), FIG.
As shown in (a), the pore radius is 2,530 nm.
The maximum value of the peak was observed at the position.

[0047]

Next, a coating solution is prepared by mixing the following components, sufficiently stirred and defoamed, and then coated on a paper serving as the substrate 101 with a gravure coater (not shown). The ink receiving layer 102 is dried at 120 ° C. in a hot air drying furnace (not shown).
Was formed by coating. At this time, the coating amount of the ink receiving layer 102 was 4 g / m ^{2 as} a dry coating amount.

The coating liquid used above will be described.
In the following composition, alumina hydrate used as an inorganic pigment was produced as follows. First, an aluminum slurry was prepared by hydrolyzing aluminum dodoxide, and the alumina slurry was adjusted to a solid content of 7.9% alumina hydrate.
Water was added until. Next, a 3.9% nitric acid aqueous solution was added to adjust the pH, and then a maturing step was performed to obtain a colloidal sol. This colloidal sol was spray-dried at 75 ° C. to obtain an alumina hydrate used in this example. Alumina hydrate was dispersed in ion-exchanged water and used as a 15% dispersion. The alumina hydrate had a BET specific surface area of 210 m ² / g and a pore volume of 0.627.
cm ³ / g.

[0050]

When the ink receiving layer of the recording medium 100 produced as described above was observed with a scanning microscope, the surface of the pulp was almost completely covered with the ink receiving layer as shown in FIG. The thickness of the ink receiving layer 102 formed on the surface was about 1.2 μm. Further, when the pore distribution was measured, as shown in FIG. 7B, in the recording medium of the present embodiment, the pore radius was represented by
Two peaks each having a maximum value were observed at two positions of 2,530 nm and 10.7 nm. FIG. 7 (a)
When the pore volume of the ink receiving layer was determined from the peak of the base paper shown in FIG. 7 and the peak of the recording medium shown in FIG. 7B, it was 0.0059 cm ³ / g.

<Evaluation> The recording medium 100 obtained above
Was evaluated according to the following method and criteria. In Table 1,
The obtained evaluation results are shown. The following items (1) to (4) were evaluated, and as an overall evaluation, those having at least one x item were rejected, and those without x were passed. (1) Texture and color of paper The recording medium was visually observed and touched to confirm whether the original texture and color of the base paper were maintained. The evaluation criteria were evaluated as ○ when there was no problem with the texture and color, and as X when there was a problem with the texture and color.

(2) Pencil Writability The presence or absence of writability was checked using a HB pencil on the surface of the ink receiving layer of the recording medium. The pencil was evaluated as ○ when there was no blur, and the pencil was evaluated as X when there was blur.

(3) Presence / absence of powder dropping The surface of the recording medium was rubbed with black paper, and the presence / absence of transfer (powder dropping) of the ink receiving layer was confirmed. A sample in which the transfer (powdering) of the ink receiving layer was not observed was evaluated as ○, and a sample in which the transfer (powdering) of the ink receiving layer was observed was evaluated as x.

(4) Printing Characteristics An ink-jet head which has a drop-on-demand ink-jet head having nozzles at an interval of 24 lines per 1 mm (600 dpi) for each ink and scans the nozzle array in the vertical direction to form an image. Using a printer, yellow (Y), magenta (M), and cyan (C) having the following compositions
Ink jet recording was performed by ejecting 10 pl of ink for each dot printing using each color ink of black and black (Bk). Further, the amount of ink in the printing of a single color ink in 1 mm ² per 24 × 24 dots (600 dpi × 600 dpi) as 100%, the amount of ink is twice monochromatic printing in two colors with a single color ink 2 color printing Therefore, three-color and four-color printing are performed at 300% each in the same manner.
% And 400%.

As a color material of each color ink, C.I. I. Direct Yellow 86, M ink has C.I.
I. Acid Red 35 and C Ink are C.I. I. Direct Blue 199 and Bk Ink have C.I. I. Using the respective dyes of Food Black 2, the following three types of inks having different dye concentrations were prepared and used, respectively.

1) Ink composition 1: High-concentration dye ink ・ Dye 3 parts ・ Diethylene glycol 5 parts ・ Polyethylene glycol 10 parts ・ Water 82 parts

2) Ink composition 2: Concentration ink in dye ・ Dye 1 part ・ Diethylene glycol 5 parts ・ Polyethylene glycol 10 parts ・ Water 84 parts

3) Ink composition 3: low-concentration ink of dye: 0.6 part of dye; 5 parts of diethylene glycol; 10 parts of polyethylene glycol; and 84.4 parts of water.

The above yellow (Y), magenta (M),
Using an ink set composed of four color inks of cyan (C) and black (Bk), the following specific items [1] to [4] relating to print characteristics were evaluated.

[1] Presence or absence of bleeding, bleeding, beading, cissing, and uneven streaks Using a four-color ink composed of ink composition 1, the above-mentioned recording apparatus uses a four-pass printing method to reduce the printing ink amount of each color from 100% (single color). Solid printing changed to 400% (4 colors), and
Printing was performed using a pattern having a boundary of each color, and the presence or absence of bleeding, bleeding, beading, cissing, and streaks was visually observed, and evaluated according to the following criteria. Not generated at 400% printing ink amount: ず Not generated at 300% printing ink amount: ○ Not generated at 100% printing ink amount: △ Generated at 100% printing ink amount: ×

[2] Image Density Using the four dye high-concentration inks of ink composition 1, the recording apparatus used the above-mentioned recording apparatus, and the ink amount of each color was 100% (single color).
The reflection image density of the solid printed image was measured using a 310TR manufactured by X-Rite Co., and the image density represented by a black value as a representative value among the obtained values was shown.

[3] Water Resistance 200% of the solid pattern printed with each ink was printed,
After leaving the ink to dry for one day, one drop of pure water was dropped on the solid pattern and left to check whether the ink flowed out. Those that did not flow out were evaluated as ○, and those that did flow out were evaluated as x.

[4] High-speed printing characteristics Using the respective inks of the ink composition 1 with a high concentration of dye, solid printing was performed in the above-mentioned recording apparatus with a printing ink amount of 200% for each color in one-pass printing, and a pattern having a boundary of each color was printed. And printing was performed, and the presence or absence of bleeding, bleeding, beading, cissing, and uneven streaks was visually observed. The case where these phenomena did not occur was evaluated as ○, and the case where these phenomena occurred was evaluated as x.

Comparative Example 1 In Example 1, the ink receiving layer 102 was formed by crosslinking alumina hydrate and water-soluble polyvinyl alcohol as a binder with boric acid, as described below. To form a recording medium of this comparative example. Further, using the obtained recording medium, an image was formed in the same manner as in Example 1, and (1) to
The evaluation of (4) was performed similarly. Table 1 shows the evaluation results. The ink receiving layer was formed in the same manner as in the method described in JP-A-7-76161.

First, 2 g of a 5% by weight aqueous solution of H ₃ BO ₃ was added to 100 g of a boehmite sol having a solid content of 18.35% by weight, which was synthesized by hydrolysis and peptization of aluminum alkoxide, and heated to 40 ° C. A 10% by weight aqueous solution of polyvinyl alcohol (degree of saponification 97%, degree of polymerization 2300) was added to 2
0.2 g was mixed to prepare a coating liquid having a solid content of 16% by weight.

Next, using the obtained coating solution, a bar coater was used so that the coating amount after drying was 23 g / m ² .
After coating on the same substrate as used in Example 1, drying in an oven at 65 ° C., and performing heat treatment at 140 ° C.,
A recording medium having an ink receiving layer formed on the surface was prepared. When the ink receiving layer of the recording medium was observed with a scanning electron microscope, as shown in FIG. 5, the pulp was covered so that the surface hardly appeared, and the film thickness was about 10.2 μm.
m and thick. Further, when the pore distribution of the recording medium was measured, as in Example 1, two peaks were observed in the pore distribution curve. The maximum value of the peak appearing on the large pore radius side due to the voids in the base paper is 2,510 nm, the maximum value of the peak due to the pores in the ink receiving layer is 6.5 nm, and the pore volume thereof is Is 0.0050 cm ³
/ G. The observation and measurement were performed in the same manner as in Example 1.

Comparative Example 2 A recording medium was obtained by forming an ink receiving layer in the same manner as in Example 1 except that the binder was not used. Further, an image was formed using the obtained recording medium in the same manner as in Example 1, and
The evaluations (1) to (4) were performed in the same manner. Table 1 shows the evaluation results. When the ink receiving layer of the recording medium was observed with a scanning electron microscope, as shown in FIG.
The alumina hydrate of the inorganic pigment entered into the gaps between the pulp fibers, and hardly covered the pulp surface. or,
The film thickness was less than 1.0 μm.

Further, when the pore distribution of the recording medium was measured, two peaks were observed in the pore distribution curve, and the maximum value of the peak that appeared on the large pore radius side due to the voids in the base paper was 2 510 nm, while the maximum value of the peak due to the pores of the ink receiving layer was 6.8 nm, and the pore volume was 0.0010 cm ³ / g. The observation and measurement were performed in the same manner as in Example 1.

(Example 2) In Example 1, the following 2 pigments having different BET specific surface areas and pore volumes were used as inorganic pigments.
An ink receiving layer was formed in the same manner as in Example 1 except that a mixture of various kinds of alumina was used, and a recording medium was obtained. The two types of alumina hydrate used were prepared by using the following hydrated alumina hydrates A and B having different physical properties by changing aging conditions and pH adjustment. Alumina hydrate A is BE
The T specific surface area is 219 m ² / g and the pore volume is 0.660
cm ³ / g. Alumina hydrate B has a BET specific surface area of 45 m ² / g and a pore volume of 0.490 cm ³ / g.
Met. The mixing ratio of alumina hydrate A and alumina hydrate B was 3: 1 in terms of weight ratio.

Using the recording medium obtained above, an image was formed in the same manner as in Example 1, and evaluations (1) to (4) were performed in the same manner. Table 1 shows the evaluation results. Also, when the pore distribution of the recording medium obtained above was measured,
Two peaks are observed in the pore distribution curve, and the maximum value of the peak of the peak appearing on the large pore radius side due to the base material is 2,550 nm, while the peak due to the pores in the ink receiving layer is The maximum value of the peak was 18.6 nm, and the pore volume was 0.00580 cm ³ / g. The measurement was performed in the same manner as in Example 1.

Example 3 Example 1 was the same as Example 1 except that the binder used was a thermosensitive gelling resin emulsion whose hydrophilicity and hydrophobicity reversibly changed at a certain temperature as a boundary. Similarly, an ink receiving layer was formed to obtain a recording medium of this example. At this time, the heat-sensitive gelling resin emulsion contains a water-soluble urethane resin and an SBR-based latex, furthermore, 2-morpholinoethyl methacrylate and 2,2-azobis (2,4-dimethylvaleronitrile).
A polymer obtained by mixing and emulsifying the mixture was used. This heat-sensitive gelled resin emulsion has about 50
It gelled at ℃ and the viscosity rose sharply.

Further, using the recording medium obtained above, an image was formed in the same manner as in Example 1, and (1) to (4)
Was similarly evaluated. Table 1 shows the evaluation results.
Also, when the pore distribution of the recording medium of the produced recording medium was measured, two peaks were observed in the pore distribution curve, and the peak pores that appeared on the large pore radius side due to the base material had The maximum value was 2,490 nm, while the maximum value of the peak due to the pores of the ink receiving layer was 17.6 nm, and the pore volume was 0.00709 cm ³ / g. The measurement was performed in the same manner as in Example 1.

[0074]

[Table 1]

(Example 4) An ink receiving layer was formed in the same manner as in Example 1 except that the inorganic pigment was changed to silica, and a recording medium of this example was obtained. The specific surface area of the silica used at this time was 145 m ² / g, and its pore volume was 0.435 cm ³ / g. Further, using the recording medium obtained above, an image was formed in the same manner as in Example 1, and the evaluations (1) to (4) were performed in the same manner. The evaluation results are shown in Table 1. When the pore distribution of the recording medium prepared above was measured, two peaks were observed in the pore distribution curve, and the maximum value of the peak of the peak that appeared on the large pore radius side due to the base material was 2 490 nm, while the maximum value of the peak due to the pores of the ink receiving layer is 2
6.6 nm with a pore volume of 0.00409 cm
³ / g. The measurement was performed in the same manner as in Example 1.

Embodiment 5 In this embodiment, an ink set including a pigment ink containing a pigment as a coloring material of the ink is used.
An image was recorded on the recording medium obtained in Example 1.
The color material of each color ink used at this time is C.I. I. Pigment Yellow 83 and M ink have C.I.
I. Pigment Red 48: 3, C ink has C.I. I.
Pigment Blue 15: 3 and Bk inks were prepared using carbon black pigments and the following three inks having different colorant concentrations were prepared and used.

For the preparation of the pigment ink, first, a pigment dispersion having the following composition was prepared by a known dispersion method using the following dispersant, and thereafter, each color ink was prepared using the dispersion. -Pigment 15 parts-Copolymer of polyethylene glycol monoacrylate having 45 mol of oxyethylene groups introduced therein and sodium acrylate [Molar ratio of monomer (former / latter) = 2/8] 3 parts-Monoethanolamine 1 Department

Using the above pigment dispersion, inks having different pigment concentrations as described below were prepared. <1> Ink composition 4: High-concentration pigment ink ・ Pigment dispersion liquid 33 parts ・ Diethylene glycol 4 parts ・ Ion exchange water 63 parts

<2> Ink composition 5: Pigment concentration ink ・ Pigment dispersion liquid 11 parts ・ Diethylene glycol 4 parts ・ Ion exchange water 85 parts

<3> Ink composition 6: low-concentration pigment ink ・ Pigment dispersion 6.6 parts ・ Diethylene glycol 4 parts ・ Ion-exchanged water 89.4 parts Same as Example 1 using the above ink set (1) ~
The evaluation of (4) was performed. Table 2 shows the evaluation results.
As shown in Table 2, it was found that good printing characteristics were obtained in the image forming method using the pigment ink as in the case of the dye ink used in Example 1.

Example 6 In this example, an ink receiving layer was formed in the same manner as in Example 1 except that the base paper used in Example 1 was subjected to emboss pattern processing. A recording medium of this example was obtained. At this time, image formation was further performed in the same manner as in Example 1, and evaluations (1) to (4) were performed in the same manner as in Example 1. Table 2 shows the evaluation results.
It was shown to. When the pore distribution of the recording medium of the produced recording medium was measured, two peaks were observed in the pore distribution curve, and the maximum value of the pore of the peak that appeared on the large pore radius side due to the base material Is 2,350 nm, while the maximum value of the peak due to the pores of the ink receiving layer is 10.6 nm.
And its pore volume was 0.004290 cm ³ / g. The measurement was performed in the same manner as in Example 1. The recording medium according to the present embodiment is an example in which an ink receiving layer similar to that of the embodiment 1 is formed on a base paper on which an emboss pattern processing is performed. It has been found that the ink has pencil writing properties without loss, has less powder dropout, and has good printing characteristics.

(Example 7) In this example, instead of the base paper made in Example 1, a paper having a basis weight of 127 g / m ^{2 and} a Steckigt sizing degree of 380 seconds was used. In the same manner as in the above, an ink receiving layer was formed to obtain a recording medium of this example. Further, image formation was performed in the same manner as in Example 1, and the same evaluations (1) to (4) as in Example 1 were performed. Table 2 shows the evaluation results. When the pore distribution of the recording medium prepared above was measured, two peaks were observed in the pore distribution curve, and the maximum value of the peak of the peak that appeared on the large pore radius side due to the base material was 2 , 250 nm, while the maximum value of the peak due to the pores of the ink receiving layer is 11.8 nm, and the pore volume is 0.0041.
It was 7 cm ³ / g. The observation and measurement were performed in the same manner as in Example 1. According to the present embodiment, even when the ink receiving layer is formed on a base paper having a high degree of Stikhito size, the recording medium of the present invention does not impair the texture of the paper, has pencil writing properties, And good print characteristics were obtained.

Comparative Example 3 In this comparative example, a recording medium in which the maximum value of the pore radius caused by the ink receiving layer was larger than 50 nm was manufactured. Further, image formation was performed in the same manner as in Example 1, and the same evaluations (1) to (4) were performed. Table 2 shows the evaluation results. Here, the maximum value of the pore radius was adjusted by adding a cationic substance twice in place of the binder in Example 1 to cause strong aggregation. 100 parts by weight of inorganic content (alumina hydrate 15% solution) 4 parts by weight of permeation scavenger (polyoxyethylene polypropylene condensate) 5 parts by weight of cationic substance (benzethonium chloride) 5 parts by weight of water 125 parts by weight The thickness of the ink receiving layer was 2.0 μm. Furthermore, when the pore distribution of the recording medium was measured,
The maximum value of the peak is two places, the maximum value of the peak of the large pore is 251 nm, the peak maximum value of the pore of this ink receiving layer is 89 nm, and the pore volume is 0.0079 cm.
³ / g. The above observation and measurement were performed in the same manner as in Example 1.

[0084]

[Table 2]

[0085]

As described above, according to the present invention,
By using a recording medium having a specific ink receiving layer composed of an inorganic pigment and a binder formed on a base material mainly composed of pulp fibers, an excellent pencil is maintained while maintaining the natural texture of the base paper. It has a writing property, has excellent ink absorption, does not depend much on the absorption of the base paper, has a high ink absorption speed, and when an image is formed, the image density is high, the color tone is clear, the resolution is high. High and excellent images,
Further, even in high-speed printing, that is, in reciprocating printing with a small number of passes, a good image with little bleeding or uneven stripes can be obtained. By using a recording medium and various base papers having the above-described characteristics and different Steckigt sizing degrees, surface shapes, and the like, it is possible to obtain a manufacturing method in which an optimum recording medium can be easily obtained.
Further, according to the present invention, there is provided an image forming method capable of obtaining an image having excellent image characteristics as described above.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a pore distribution curve of an example of a recording medium of the present invention.

FIG. 3 is a schematic view of a diagram obtained by observing and photographing the surface of a base paper used in Examples and Comparative Examples with a scanning microscope.

FIG. 4 is a schematic diagram of a diagram in which the surface of a recording medium of Example 1 of the present invention is observed and photographed with a scanning microscope.

FIG. 5 is a schematic diagram of a diagram in which the surface of a recording medium of Comparative Example 1 is observed and photographed with a scanning microscope.

FIG. 6 is a schematic diagram of a diagram obtained by observing and photographing the surface of a recording medium of Comparative Example 2 with a scanning microscope.

7A is a diagram illustrating a pore distribution curve of a recording medium of Example 1 of the present invention, and FIG. 7B is a diagram illustrating a pore distribution curve of a base paper used for the recording medium.

[Explanation of symbols]

 100: Recording medium 101: Base material 102: Ink receiving layer

Claims (19)

[Claims] 1. In a recording medium in which an ink receiving layer having an inorganic pigment and a binder is formed on a base material mainly composed of pulp fibers, the coating amount of the ink receiving layer is 1 to 10 g / m 2. ² , and the pore distribution of the recording medium has the maximum value of the pore radius of the base material and the maximum value of the pore radius of the ink receiving layer, and the fineness of the ink receiving layer. A recording medium, wherein the maximum value of the pore radius is in the range of 8 nm to 50 nm. 2. The ink receiving layer, wherein a pore radius is 8 nm or more.
2. The recording medium according to claim 1, wherein the total volume of the pores of 50 nm is 0.004 cm ³ / g or more. 3. The specific recording medium according to claim 1, wherein the ratio of the pore volume of the base material to the pore volume of the ink receiving layer is 1/10 or less. 4. The recording medium according to claim 1, wherein the ink receiving layer is composed of an aggregate of an aggregate composed of an inorganic pigment and a binder. 5. The recording medium according to claim 1, wherein a cationic substance is further contained in the ink receiving layer. 6. The recording medium according to claim 1, wherein the ink receiving layer further contains a penetration aid. 7. The recording medium according to claim 1, wherein 90% or more of the surface of the substrate is covered with an ink receiving layer. 8. The recording medium according to claim 1, wherein minute cracks are formed on the surface of the ink receiving layer. 9. The maximum value of the pore radius of the substrate is 500.
The recording medium according to claim 1, wherein the recording medium is in a range of 10 nm to 10,000 nm. 10. A method for producing a recording medium in which an ink receiving layer is formed on a base material mainly composed of pulp fibers, wherein the ink receiving layer comprises an inorganic pigment, a binder, A dispersion containing at least a resin emulsion containing a resin is used as a coating liquid, and the coating liquid is applied so that the dry coating amount is 1 to 10 g / m ^2, and thereafter, the inorganic pigment and the resin The pore distribution of the recording medium obtained by weakly aggregating the emulsion and drying it further is as follows:
The ink receiving layer is formed so as to have the maximum value of the pore radius of the base material and the maximum value of the pore radius of the ink receiving layer, and to have the maximum value of the pore radius of the ink receiving layer in the range of 8 nm to 50 nm. A method for manufacturing a recording medium, comprising: 11. An inorganic pigment having a pore volume of 0.1 to 0.1.
The method for manufacturing a recording medium according to claim 10, wherein the recording medium having a density of 3.0 cm ³ / g is used. 12. An inorganic pigment having a BET specific surface area of 1
The method for producing a recording medium according to claim 10, wherein the recording medium has a thickness of 0 to 500 m ² / g. 13. The method according to claim 10, wherein the inorganic pigment contains at least one of alumina hydrate and silica. 14. The method for producing a recording medium according to claim 10, wherein a binder containing a component whose hydrophilicity and hydrophobicity reversibly change at a certain temperature as a boundary is used as the binder. 15. A binder having a glass transition temperature in the range of 20 ° C. to 120 ° C. as a binder.
3. The method for manufacturing a recording medium according to claim 1. 16. The maximum value of the pore radius of the substrate is 50.
The method for manufacturing a recording medium according to claim 10, wherein the thickness is from 0 nm to 10,000 nm. 17. An image forming method for forming an image by applying ink to a recording medium, wherein the recording medium is the recording medium according to any one of claims 1 to 9. Image forming method. 18. The image forming method according to claim 17, wherein an ink jet recording method is used for forming an image by applying ink to a recording medium. 19. The image forming method according to claim 18, wherein the ink jet recording method is a method in which thermal energy is applied to ink to discharge ink droplets.