JP2002211121A - Image receiving medium, method for manufacturing the same and image forming method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image receiving medium excellent in ink absorbability, capable of leaving the feeling of plain paper on its surface, forming an image having high image density and a sharp hue and especially suitable for ink jet recording, to provide a method for manufacturing the same, and to provide an image forming method using the image receiving medium. SOLUTION: An alumina hydrate having a boehmite structure and a cationic resin are allowed to be present at least in the vicinity of the surface of an ink receiving surface having a size-free single-layered fibrous structure based on a fibrous substrate containing no filler to form the image receiving medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium suitable for recording using ink. The present invention relates to a recording medium having an excellent ink absorbing ability and having an image recorded on the surface of the recording medium while keeping the surface of plain paper. The present invention relates to a recording medium which has a high image density and a clear color tone and is particularly suitable for inkjet, a method for manufacturing the same, and an image forming method using the recording medium.

[0002]

2. Description of the Related Art In recent years, an ink jet recording system records an image, a character, or the like by causing a minute droplet of ink to fly by various operating principles and adhere to a recording medium such as paper. A recording device to which this recording method is applied,
Features include high speed, low noise, easy multi-coloring, great flexibility in recording patterns, and no need for development and fixing. Are rapidly spreading.

Further, it is possible to obtain an image formed by the multicolor ink jet system, which is comparable to multicolor printing by the plate making system or printing by the color photographic system. Are being widely applied to the field of full-color image recording because they are cheaper than ordinary multicolor printing and printing.

[0004] In the ink jet recording system, recording devices and recording methods have been improved with improvements in recording characteristics such as higher recording speed, higher definition, and full color printing.
Advanced characteristics have also been required for recording media.

In order to meet such demands, various types of recording media have been proposed. For example, Japanese Patent Application Laid-Open No. 55-5830 proposes an ink jet recording paper having a support surface provided with an ink-absorbing coating layer, and Japanese Patent Application Laid-Open No. 55-5158 discloses a non- pigment as a pigment in a coating layer. Examples using crystalline silica have been proposed. These recording media adopt a form in which an ink receiving layer containing a pigment such as alumina or silica is formed on a base material. However, in these embodiments, since the ink receiving layer is formed on the substrate, the texture of plain paper is not obtained even when a paper substrate is used as the substrate.

As a technique for obtaining a plain paper-like recording medium, for example, Japanese Patent Application Laid-Open Nos.
In JP-A Nos. 25131 and 7-25132, a very small amount of ultrafine particles is coated on a paper base to leave a pulp fiber shape on the recording surface, and the coverage of the ultrafine particle pigment is 70% or more. A medium has been proposed. In another form, for example, Japanese Patent Application Laid-Open No. 1-141483 discloses an inkjet recording paper in which amorphous silica and alumina hydrate are on-machine coated.
Pigment size coated information recording paper has been proposed.

For these techniques, a medium in which a filler or the like is internally added to paper has been proposed. For example, JP-A-53-4
No. 9113 proposes a recording paper in which a water-soluble polymer is applied and impregnated on a sheet in which a urea formalin resin powder is internally added. JP-A-58-8865 proposes a recording paper in which a water-soluble polymer is applied and impregnated on a sheet internally containing a synthetic silicate and glass fibers. These are inks in which specific fine powder is internally added to non-size paper to improve ink absorbency.

As another form of the internal paper, a paper having a multilayer structure has been proposed. For example, JP-A-63-118287
Japanese Patent Application Publication and U.S. Pat. No. 4,734,336 propose an uncoated paper in which a support layer made of pulp fibers and a surface layer made of fillers such as silica and fibers are superposed. Further, JP-A-1-78877 and JP-A-2-24
No. 3381, No. 2-243382, No. 5-1
Japanese Patent Application Laid-Open No. 06197 proposes a recording paper in which a base layer or a mating surface of a base layer and a surface layer is subjected to a size treatment with a multi-layered paper by lamination. Also, Japanese Patent Application Laid-Open No. Hei 6-21904
No. 3 proposes a multilayer paper having a surface layer carrying a hardly soluble or water-insoluble inorganic substance. In addition, Japanese Unexamined Patent Publication No.
287886, 7-5430, 8-2
No. 58400 proposes a multilayer paper using a specific pulp such as bulky cellulose, mercerized pulp, and hardwood bleached sulphite pulp. Also, Japanese Patent Application Laid-Open
Japanese Patent No. 170190 proposes a multilayer paper in which the surface layer is mainly composed of hydrophilic fibers and hydrophobic fibers, and the base layer is mainly composed of cellulose fibers.

[0009]

However, in a conventional recording medium, the ink absorption and the ink absorption when high-speed printing is performed are reduced.
There is a problem that characteristics such as color density and bleeding may not be all satisfied.

[0010] An object of the present invention is to provide an ink having excellent ink absorbing ability,
A recording medium having high image density and a clear color tone when an image is recorded on the surface of the recording medium while leaving the texture of plain paper, and particularly suitable for inkjet, a method for manufacturing the same, and the recording method An object of the present invention is to provide an image forming method using a medium.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has an excellent ink absorbing ability, has less powder drop and curl, and has an image recorded on a paper surface having the texture of plain paper. It is an object of the present invention to provide a recording medium which has a high image density and a clear color tone when it is formed, and is particularly suitable for inkjet, a method for manufacturing the same, and an image forming method using the recording medium.

[0012]

The above objects are achieved by the present invention described below. That is, the recording medium according to the present invention is mainly composed of a fibrous substance, and has a filler-free non-sized single-layer fibrous structure, and a surface formed by the single-layer fibrous structure is an ink receiving surface. A recording medium, characterized in that alumina hydrate having a boehmite structure and a cationic resin are present at least near the surface of the fibrous substance.

[0013] Further, a method of manufacturing a recording medium according to the present invention is a method of manufacturing a recording medium having the above structure, wherein the base material has a single-layer fibrous structure mainly composed of a fibrous substance and containing no filler. And a step of providing an alumina hydrate having a boehmite structure and a cationic resin.

The image forming method according to the present invention is directed to an image forming method in which ink droplets are applied to an ink receiving surface of a recording medium to perform printing, wherein the recording medium having the above-described configuration is used as the recording medium. It is characterized by the following.

According to the present invention, the ink has excellent ink absorbing ability,
It is possible to provide a recording medium which has less powder dropout and curl, has a paper surface with the texture of plain paper, has a high image density when an image is recorded, and has a clear color tone. This recording medium can be suitably used for a recording method in which ink is applied to a recording medium to perform recording, in particular, an ink jet recording method, and has a feeling of plain paper, a high image density, and a clear color tone. A recorded image can be obtained.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present inventors have already proposed a recording medium in which alumina hydrate is internally added to a fibrous substance (for example, Japanese Patent Nos. 2714350 to 2714352,
JP-A-9-99627 and 2000-21125
No. 0). Among these, Patent No. 2714350
Nos. 2 to 2714352 and JP-A-9-99627 are recording media in which alumina hydrate exhibiting specific physical properties is internally added, and alumina hydrate is a fibrous substance. It is internally added throughout. The present invention has been made based on the finding that good coloring can be obtained even on uncoated paper by adopting such a configuration. further,
The recording medium disclosed in Japanese Patent Application Laid-Open No. 2000-212250 is a paper medium having a multilayer structure composed of a surface layer and a base layer, and has a surface layer to which alumina hydrate having a boehmite structure is internally added. Medium. The present invention provides a high-speed recording paper having a multi-layered recording paper internally containing alumina hydrate, and internally adding alumina hydrate only to the surface layer, and forming the base layer from a material having good liquid absorbability. This is based on the finding that the coloring and the resolution of printing are excellent.

The present invention is an improvement on these inventions. In other words, the present inventors have improved the structure of a recording medium containing alumina hydrate internally, and have used a fibrous substance containing no filler, even for a recording medium having a single-layer structure, to use non-size paper. And made it possible to obtain good ink absorption, color development and dot reproducibility by making alumina hydrate and cationic resin present near the surface of the fibrous substance. The present invention has been made based on such findings.

The recording medium according to the present invention is particularly effective when printing is performed by an ultrahigh-speed machine using a full line head or the like. A further preferred form of the recording medium of the present invention is a form in which alumina hydrate and a cationic resin are applied to non-size paper on-machine. The recording medium of the present invention has a single-layer structure, and can be easily manufactured on a normal paper machine because alumina hydrate and a cationic resin are applied on-machine, and the productivity is significantly improved. Is one of its advantages. In particular, there is also an advantage that both-side coating of alumina hydrate and a cationic resin on a substrate can be easily performed. In the present invention, the fibrous substance need not be limited to paper, but synthetic paper using synthetic pulp or the like, cloth,
This is a recording medium in which alumina hydrate and a cationic resin are present, which is applicable to all forms using a fibrous material such as a nonwoven fabric. In the recording medium of the present invention, the coloring material in the printed ink is adsorbed near the surface of the ink receiving surface of the recording medium, and the solvent component in the ink penetrates into the recording medium and is absorbed. . It is preferable that there are no additional materials such as alumina hydrate and cationic resin in the gaps between the fibers of the fibrous substance. Methods for confirming that no filler is present in the gaps between the fibers of the fibrous substance include, for example, JP-A-6-321572 and JP-A-7-25.
As described in JP-A-131 and JP-A-7-25132, a method of observing the surface of a recording medium with a scanning electron microscope can be used. Preferred observation magnification is 200
It is in the range of up to 500 times. In the present invention, it is preferable that the gap between fibrous substances is left as much as possible to maximize the ink absorption when printing by inkjet. Therefore, it is important that no filler is present in the gaps between the fibers. Further, in the present invention, application of a resin material such as a surface size press used for ordinary paper or cloth is not performed. In the recording medium of the present invention, as shown in FIG. 1, alumina hydrate 3 and a cationic resin adhere to the surface of each fiber 1 of the fibrous substance so as to cover the surface of each fiber 1. ing. Here, the alumina hydrate or the cationic resin is preferably present so as not to fill the gap 2 between the fibrous substances.

In the present invention, alumina hydrate and a cationic resin are present at least in the vicinity of the ink receiving surface formed of a single-layer fibrous structure mainly composed of a fibrous substance. As a method of adding the alumina hydrate and the cationic resin, a method of internally adding a recording medium base material having a single-layer fibrous structure mainly composed of a fibrous substance, and a method of adding these materials to a predetermined surface of the base material are used. Coating or impregnating methods can be used. A method of coating or impregnating the recording medium with the alumina hydrate and the cationic resin is preferable. In the method of applying the alumina hydrate and the cationic resin, more alumina hydrate and the cationic resin can be present in the vicinity of the surface of the recording medium, and the color development and the like are improved. A more preferable method is a method in which alumina hydrate and a cationic resin are applied on-machine. The reason for this is not clear, but in the case of on-machine coating, paper and other materials have a high chemical and physical activity immediately after papermaking, and the activity of the contacted alumina hydrate and cationic resin is high. Or because the time between applying the alumina hydrate or the cationic resin to the fibrous material and attaching it to the fibrous material is short, because the coating liquid does not easily penetrate in the center direction of the base material. I guess.

When the recording medium is formed into a sheet, the preferred coating amount is 1 to 5 g / m 2 per side.
² In the case of on-machine coating, both sides are coated simultaneously. In this case, the preferable coating amount of the alumina hydrate and the cationic resin is ² to 10 g / m ^{2 on} both sides.
It is. Within this range, the alumina hydrate or the cationic resin can more suitably secure the gap between the fibrous substances. Further, by performing on-machine coating, a good color development can be obtained with a small coating amount and with the texture of plain paper remaining.

Here, the "feel" of plain paper refers to a paper having a fibrous material exposed on its surface and having no feeling as if fine particles are applied to its touch. Here, the on-machine coating means that a resin material such as starch is placed on a fibrous substance usually performed in a paper making process, as described in JP-A-1-141773 and JP-A-11-174718. Instead of applying in a size press process, a coating solution containing alumina hydrate and a cationic resin is continuously applied on-machine in a paper making process. Therefore, in the recording medium according to the present invention, the size press layer does not exist on the surface of the recording medium.

Japanese Patent Application Laid-Open No. 1-141783 discloses a coating liquid containing amorphous silica and alumina hydrate having an average particle diameter of 5 to 200 nm in a weight ratio of 100: 5 to 100: 35 on a support. Discloses an ink jet recording paper obtained by on-machine coating. In the present invention, alumina sol is used as a binder of amorphous silica to be applied for the purpose of improving productivity in on-machine coating on a paper machine. This recording paper is the same as the recording medium of the present invention in that on-machine coating is performed, but alumina hydrate and a cationic resin are added to a filler-free non-size paper as in the present invention. This is different from the configuration for coating.

JP-A-11-174718 discloses a paper coated with a pigment size of ³ to 8 g / m ² per one side of a base paper and having a finish density of 0.75 to 0.75 g / m ^2.
0.90 g / cm ³ range, fiber orientation ratio 1.05
An information sheet having a range of 1.25, a range of smoothness of 50 to 120 seconds, and a formation index of 20 or more is disclosed.
In the present invention, the rigidity is maintained while maintaining the color image of the full-color copying machine in good condition, and in order to prevent the toner fixed when the density of the paper is reduced in order to reduce the grammage, the toner is prevented from entering the gap between the papers. Pigment size coating. This paper is the same as the recording medium of the present invention in that pigment size coating is performed on a specific range of paper. However, Japanese Patent Application Laid-Open No. 11-174718 discloses an ink jet recording method as in the present invention. There is no description of the idea of on-machine coating of alumina hydrate and a cationic resin on a filler-free paper, which has properties that can satisfy properties such as absorbency, color development, and texture of plain paper.

Since alumina hydrate has a positive charge, by incorporating it into the recording medium, the coloring material such as the dye in the ink can be fixed well, and an image having excellent coloring properties can be obtained. Further, there is an advantage that problems such as browning of the black ink and light fastness do not occur. Therefore, a recording medium containing alumina hydrate is preferable as one used for inkjet recording.

As the alumina hydrate present in the recording medium of the present invention, an alumina hydrate having a boehmite structure by an X-ray diffraction method has good ink absorption, coloring material adsorbing properties and coloring properties. Most preferred.

Alumina hydrate is defined by the following general formula:

[0027]

Embedded image

In the formula, n represents one of the integers from 0 to 3;
Represents a value of 0 to 10, preferably 0 to 5. m
The expression H ₂ O describes a detachable aqueous phase which is often not involved in the formation of the crystal lattice, and
Can also take non-integer values. However, m and n do not become zero at the same time.

In general, alumina hydrate crystals having a boehmite structure are layered compounds in which the (020) plane forms a giant plane, and exhibit a diffraction peak specific to an X-ray diffraction pattern. As the boehmite structure, a structure containing excess water between layers on the (020) plane, called pseudo-boehmite, in addition to complete boehmite, may be employed. This pseudo boehmite X
The line diffraction pattern shows a broader diffraction peak than perfect boehmite. Since complete boehmite and pseudo-boehmite cannot be clearly distinguished, in the present invention, unless otherwise specified, they are referred to as an alumina hydrate having a boehmite structure (hereinafter referred to as alumina hydrate).

As the alumina hydrate having a boehmite structure used in the present invention, those exhibiting a boehmite structure by an X-ray diffraction method are preferable because of good color density, resolution and ink absorbency. Further, as long as the alumina hydrate has a boehmite structure, an alumina hydrate containing a metal compound such as titanium dioxide or silica can be used. The method for producing the alumina hydrate used in the present invention is not particularly limited, but any method capable of producing an alumina hydrate having a boehmite structure includes, for example, hydrolysis of aluminum alkoxide and sodium aluminate. It can be produced by a known method such as hydrolysis. Also, Japanese Patent Application Laid-Open
As disclosed in JP-A-120508, an alumina hydrate that is amorphous by X-ray diffraction can be used in the form of a boehmite structure by heat treatment at 50 ° C. or higher in the presence of water.

The non-sized base material having a single-layer fibrous structure constituting the recording medium according to the present invention can be obtained mainly from unsized fibrous substances. Cellulose pulp can be used as the fibrous substance.

Specific examples include sulfite pulp (SP) obtained from hardwood and softwood,
Used paper pulp, which is deinked secondary fiber, such as chemical pulp such as alkali pulp (AP) and kraft pulp (KP), semi-chemical pulp, semi-mechanical pulp, and mechanical pulp can be used. The pulp can be used without distinction between unbleached pulp, bleached pulp, beaten, and unbeaten. Further, as the cellulose pulp, non-wood pulp grass, leaves, bast, fibers such as seed hair, for example, straw,
Pulp such as bamboo, hemp, bagasse, kenaf, honey and cotton linter can also be used. In the present invention, it is necessary that no filler is contained. Further, it is preferable not to include a water-absorbing resin such as polyvinyl alcohol and polyacrylamide. By not including the filler and the water-absorbing resin, good reproducibility of the printed dots can be obtained.

The basis weight of the entire recording medium is not particularly limited as long as the basis weight is small and the recording medium is not extremely thin, but the range of 40 to 300 g / m ² when printing with a printer or the like is considered. It is preferable in terms of properties. A more preferred range is from 45 to 200 g / m ² , and the opacity can be increased without increasing the folding strength of the paper.
Further, sticking is less likely to occur when a large number of print samples are stacked.

In the recording medium of the present invention, in addition to the above cellulose pulp, sulfated pulp, sulfite pulp, soda pulp, hemicellulase-treated pulp, and enzyme-treated pulp made from fine fibrillated cellulose, crystallized cellulose, hardwood or softwood are used as raw materials. It is preferred to add at least one such as chemical pulp. Addition of these pulp not only has the effect of improving the smoothness of the surface of the recording medium and improving the texture, but also has the effect of eliminating tack and swelling deformation on the surface of the recording medium immediately after printing.

In the present invention, in addition to the above cellulose pulp, bulky cellulose fibers, mercerized cellulose,
At least one of fluffed cellulose and mechanical pulp such as thermomechanical pulp can be added for use. By adding these pulp, the ink absorption speed and the ink absorption amount of the recording medium can be improved.

In the present invention, the ink absorption rate of the recording medium can be measured by a known dynamic scanning absorptiometer.
The recording medium of the present invention preferably has an absorption amount of at least 50 ml / m ^{2 with} a contact time of 25 milliseconds for a liquid. Within this range, there is an effect that beading can be prevented regardless of the ink composition. Further, it is preferable that the contact time is 100 milliseconds and the absorption amount is at least 100 ml / m ² . Within this range, it is possible to prevent the occurrence of bleeding, bleeding and beading even when performing multiple printing at high speed.

The liquid absorption rate and absorption amount can be controlled to desired values by the type of cellulose pulp used and the degree of beating. In the recording medium of the present invention, the absorbability can be particularly improved by adding at least one of the bulky cellulose, mercerized cellulose, fluffed cellulose and mechanical pulp. Further, it is possible to improve the surface properties of the recording medium by adding at least one of fibrillated cellulose, crystallized cellulose, sulfate pulp, sulfite pulp, soda pulp, hemicellulase-treated pulp and enzyme-treated chemical pulp. it can.

As a method for manufacturing a recording medium according to the present invention, a generally used paper manufacturing method can be applied. As the papermaking apparatus, a conventional fourdrinier paper machine, a round net paper machine, a cylinder, a twin wire, or the like can be used.

In the recording medium of the present invention, starch or the like is not applied in the size press step performed in the usual paper manufacturing method. Instead, alumina hydrate and a cationic resin are applied. This coating is preferably on-machine coating. As the on-machine coating method, a general coating method can be selected and used. For example, a coating technique using a gate roll coater, a size press, a bar coater, a blade coater, an air knife coater, a roll coater, a brush coater, a curtain coater, a gravure coater, a spray device, or the like can be employed. Alumina hydrate and the cationic resin can be freely selected from a method of applying by mixing and a method of independently applying on-machine coating.

In the present invention, the surface of the recording medium coated with the on-machine can be smoothed by performing a calendar process or a super calendar process as necessary.

The alumina hydrate used in the present invention is an alumina hydrate having a boehmite structure. If it shows a boehmite structure by X-ray diffraction, it contains a metal oxide such as titanium dioxide or silica. Alumina hydrate can also be used. As the alumina hydrate having a boehmite structure containing titanium dioxide, for example, Japanese Patent No. 2714351
The one described in Japanese Patent Application Laid-Open Publication No. H10-26095 can be used. As the alumina hydrate having a boehmite structure containing silica, for example, those described in JP-A-2000-79755 can be used. Another form is magnesium, calcium, strontium, barium, zinc, boron, silicon, germanium, tin, lead, zirconium, indium, phosphorus, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, instead of titanium dioxide and silica. At least one of oxides and compounds such as manganese, iron, cobalt, nickel and ruthenium can be used.

The shape of alumina hydrate (particle shape, particle size,
(Aspect ratio) is made by dispersing alumina hydrate in ion-exchanged water and dropping it on the collodion membrane to make a sample for measurement.
It can be measured by observing this sample with a transmission electron microscope. Among the alumina hydrates, pseudoboehmite is described in the literature (Rosek J., et al, A
applied Catalysis, vol. 74, 29-3
6, 1991), it is generally known that there are cilia and other shapes. In the present invention, either cilia-shaped or plate-shaped alumina hydrate can be used.

The aspect ratio of the tabular grains can be determined by the method defined in Japanese Patent Publication No. 5-16015. The aspect ratio indicates the ratio of the diameter to the thickness of a particle. Here, the diameter indicates the diameter of a circle having an area equal to the projected area of the particles when the alumina hydrate is observed with a microscope or an electron microscope. The aspect ratio is the ratio of the diameter indicating the minimum value to the diameter indicating the maximum value of the flat surface, observed in the same manner as the aspect ratio. In the case of a hairy bundle shape, the method of determining the aspect ratio is to obtain the diameter and length of the upper and lower circles using the individual acicular particles of alumina hydrate forming the hairy bundle as a cylinder, Can be obtained by taking the ratio of the length to. The most preferred shape of alumina hydrate is a flat plate having an average aspect ratio of 3
In the range of from 10 to 10, the average particle diameter is preferably in the range of 1 to 50 nm. For hairy bundles, the average aspect ratio is in the range of 3 to 10, and the average particle length is preferably in the range of 1 to 50 nm.
When the average aspect ratio is in the above range, a gap is formed between the particles when internally added to the fibrous substance, so that a porous structure having a wide pore radius distribution is easily formed in the layer made of alumina hydrate. be able to. When the average particle diameter or the average particle length is within the above range, a porous structure having a large pore volume can be similarly formed.

The BET specific surface area of the alumina hydrate of the present invention is preferably in the range of 70 to 300 m ² / g. If the BET specific surface area is smaller than the above range, the printed portion may become cloudy or the image may have insufficient water resistance. When the BET specific surface area is larger than the above range,
In some cases, powder falling easily occurs.

The BET specific surface area, pore radius distribution, and pore volume of alumina hydrate can be determined by a nitrogen adsorption / desorption method.

The crystal structure of the alumina hydrate in the recording medium can be measured by a general X-ray diffraction method.
The recording medium containing alumina hydrate was attached to the measurement cell, and the diffraction angle 2θ appeared at 14 to 15 ° (020).
The peak of the plane was measured, and from the diffraction angle 2θ of the peak and the half width B, the plane interval of the (020) plane was determined by Bragg.
g), and the crystal thickness in the direction perpendicular to the (010) plane can be obtained using Scherrer's equation.

In the present invention, the spacing between the (020) planes of the alumina hydrate in the recording medium is preferably in the range of more than 0.617 nm and not more than 0.620 nm. In this range, the range of selection of coloring materials such as dyes to be used is widened, and even if printing is performed using either hydrophobic or hydrophilic coloring materials, the optical density of the printed portion is increased, and bleeding and beading, The occurrence of cissing is reduced. Further, even when printing is performed using a hydrophobic or hydrophilic coloring material in combination, the optical density and the printing dot diameter become uniform regardless of the type of coloring material. Even if the ink contains a hydrophilic or hydrophobic material, there is no change in the optical density or dot diameter of the printed portion, and bleeding, beading, and cissing are reduced. The crystal thickness in the direction perpendicular to the (010) plane is preferably in the range of 6.0 to 10.0 nm. Within this range, the ink absorption of the recording medium and the adsorbability of the coloring material are good, and powder fall is reduced. A method for setting the interplanar spacing of the (020) plane and the crystal thickness in the direction perpendicular to the (010) plane of the alumina hydrate in the recording medium within the above ranges is described in, for example, JP-A-9-996.
The method described in Japanese Patent Publication No. 27 can be used.

The crystallinity of the alumina hydrate in the recording medium can be similarly determined by the X-ray diffraction method. A recording medium into which alumina hydrate was added was pulverized, attached to a measurement cell, and measured at a diffraction angle 2θ of 10 ° and 2θ.
Is measured at 14 to 15 °, and the crystallinity can be determined from the peak intensity of the (020) plane with respect to the peak intensity at 2θ = 10 °. The crystallinity of the alumina hydrate in the recording medium is preferably in the range of 15 to 80. Within this range, the ink absorbency is improved and the water resistance of the printed image is improved. As a method for controlling the crystallinity of the alumina hydrate in the recording medium within the above range, for example, a method described in JP-A-8-132731 can be used.

The preferred pore structure of the alumina hydrate used is the following three types, and one or more types can be selected and used as needed.

According to the first pore structure of the present invention, the alumina hydrate has an average pore radius of 2.0 to 20.0 nm.
The half width of the pore radius distribution is 2.0 to 15.0 nm. Here, the average pore radius is disclosed in JP-A-51-3829.
8 and JP-A-4-202011. Further, the half width of the pore radius distribution indicates the width of the pore radius which is half the frequency of the average pore radius in the measurement results of the pore diameter distribution. If the average pore radius and half-value width in the above range, the selection range of usable coloring materials is wide, and even if a hydrophobic or hydrophilic coloring material is used, bleeding, beading, and repelling hardly occur, and The density and the dot diameter become uniform. The alumina hydrate having the above pore structure can be produced, for example, by the method described in the specification of Japanese Patent No. 2714352.

The second pore structure in the present invention is such that the alumina hydrate has a radius of 10.0 nm in the pore radius distribution.
The following and the radius have a maximum in the range of 10.0 to 20.0 nm, respectively. Radius 10.0-20.0n
absorbs the solvent component in the ink with relatively large pores of m,
A relatively small pore having a radius of 10.0 nm or less adsorbs a coloring material component such as a coloring material in the ink. Therefore, both the absorption of the coloring material and the absorption of the solvent become faster. The maximum at a radius of 10.0 nm or less is more preferably at a radius of 1.0 to 6.0 nm, and within this range, adsorption of the coloring material is accelerated. The maximum pore volume ratio (volume ratio of the maximum 2) having a pore radius of 10.0 nm or less should be 0.1 to 10% of the total pore volume, so that both the ink absorption property and the color material fixing property are improved. It is preferable because it satisfies, and more preferably, it is in a range of 1 to 5%. The alumina hydrate having the above pore structure is disclosed in, for example, Japanese Patent No. 27143.
No. 50 can be made by the method described in the specification.
As another method, a method in which an alumina hydrate having a peak at a radius of 10.0 nm and an alumina hydrate having a peak between a radius of 10.0 and 20.0 can be used in combination.

In the third pore structure of the present invention, the alumina hydrate has a pore radius distribution of a radius of 2.0 to 20.
It has a maximum peak in the range of 0 nm. Having a peak in this range satisfies both the ink absorption and the coloring material adsorption, improves the transparency of the alumina hydrate, and can prevent the image from becoming cloudy. The more preferable range of the maximum peak is 6.0 to 20.0 nm, and within this range, any one of the ink using the pigment, the ink using the dye, the ink using the dye ink and the pigment ink, and the mixed ink as the coloring material is used. Even if printing is performed with ink, it is possible to prevent the occurrence of bleeding, bleeding, and color unevenness. The most preferred range is radius 6.
The range is from 0 to 16.0 nm. Within this range, even when three or more types of inks having different color material densities are used, there is no difference in tint due to the densities. The alumina hydrate having the above pore structure can be prepared, for example, by the method described in JP-A-9-6664.

The total pore volume of alumina hydrate is from 0.4 to
A range of 1.0 cm ³ / g is preferred. Within this range, the ink absorbency is good and the color is not impaired even when multicolor printing is performed. A more preferred range is 0.4 to
The range of 0.6 cm ³ / g is preferable because powder falling and image bleeding hardly occur. Further, it is more preferable that the pore volume of alumina hydrate having a radius in the range of 2.0 to 20.0 nm is 80% or more of the total pore volume, since the printed image does not become cloudy. As another form, it is also possible to use alumina hydrate by aggregating it. It is preferable that the particle diameter is 0.5 to 50 μm and the value of BET specific surface area / pore volume is 50 to 500 m ² / ml. Within this range, since many adsorption points of the alumina particles are exposed, it is possible to prevent the occurrence of beading regardless of the printing environment (temperature and humidity). For the aggregated particles having the above pore structure, for example, a method described in JP-A-8-174993 can be used.

In the present invention, an alumina hydrate treated with a coupling agent can be used. The coupling agent used may be one of silane, titanate, aluminum and zirconium coupling agents.
More than one kind can be selected and used. It is preferable that the alumina hydrate is hydrophobized by the coupling agent, since the color density of the image is high and a clear image can be obtained. When the coupling agent treatment is performed within the range of 0.1 to 30% in terms of the surface area of the entire alumina hydrate, the color developability can be enhanced without impairing the ink absorbency. The above-mentioned coupling agent treatment method can be performed, for example, by the method described in JP-A-9-76628.

In the present invention, a metal alkoxide and a substance capable of crosslinking a hydroxyl group may be added to alumina hydrate for use. The metal alkoxide can be freely selected and used from commonly used materials such as tetraethoxysilane and tetramethoxysilane. As a material capable of crosslinking a hydroxyl group, for example, boric acid, a boric acid compound, a formalin compound, or the like can be freely selected and used. The processing method can be performed, for example, by the method described in JP-A-9-86035. By adding these materials, it is possible to prevent the occurrence of bleeding and beading even when printing is performed using an ink having a high permeability and a good permeability.

The cationic resin used in the present invention includes:
Freely selected from materials such as quaternary ammonium salts, polyamines, alkylamines, halogenated quaternary ammonium salts, cationic urethane resins, benzalkonium chloride, benzethonium chloride, and dimethyldiallylammonium chloride polymer Can be. The surface resistance of the recording medium of the present invention is 2 × 10 ¹¹ Ω / □ to 1 × 10
A range of ¹³ Ω / □ is preferred. The recording medium may be charged while being conveyed in the recording apparatus, and when ink-jet recording is performed on the charged recording medium, the ink collides with the recording medium and then bounces to generate ink mist. There is. However, by setting the surface resistance of the recording medium within the above range, the occurrence of such ink mist can be reduced.

As the ink used in the image forming method of the present invention, one containing mainly a colorant (dye or pigment), a water-soluble organic solvent and water can be used.

As the dye, for example, a water-soluble dye typified by a direct dye, an acid dye, a basic dye, a reactive dye, an edible dye and the like are preferable. Any material can be used as long as it provides an image that satisfies the required performance, such as sharpness, stability, and light resistance. As the pigment, carbon black or the like is preferable. A method using a pigment and a dispersant in combination, a method using a self-dispersing pigment, and a method for microencapsulation are also possible.

The water-soluble dye is generally used by dissolving it in water or a solvent comprising water and a water-soluble organic solvent. These solvent components preferably include water and various water-soluble organic solvents. Is used, but it is preferable to adjust the water content in the ink to fall within a range of 20 to 90% by weight.

Examples of the water-soluble organic solvent include alkyl alcohols having 1 to 4 carbon atoms such as methyl alcohol; amides such as dimethylformamide; ketones or ketone alcohols such as acetone; ethers such as tetrahydrofuran; Polyalkylene glycols such as glycol, alkylene glycols such as ethylene glycol, alkylene glycols having 2 to 6 carbon atoms, glycerin, ethylene glycol methyl ether, lower alkyl ethers of polyhydric alcohols such as, and the like, One selected from these or a combination of two or more can be used.

Of these many water-soluble organic solvents,
Polyhydric alcohols such as diethylene glycol, and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl ether and triethylene glycol monoethyl ether are preferred. Polyhydric alcohols are
It is particularly preferable because the effect of a lubricant for preventing a decrease in nozzle clogging due to evaporation of water in the ink and precipitation of a water-soluble dye is large.

A solubilizer can 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. In order to further improve the properties, a viscosity modifier, a surfactant, a surface tension modifier, p
Additives such as an H adjustor and a specific resistance adjuster can be used.

As a method of forming an image by applying the ink to the recording medium, an ink jet recording method can be suitably used. As this inkjet recording method,
The recording method may be any method as long as the ink can be effectively removed from the fine holes (nozzles) and applied to the recording medium. In particular, JP-A-54-59936
In the method described in Japanese Patent Application Laid-Open Publication No. H10-260, it is possible to particularly effectively use an ink jet system in which ink subjected to the action of thermal energy causes a rapid volume change, and the ink is ejected from a nozzle by an action force due to this state change. it can.

[0064]

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

The physical properties used in the present invention were measured as follows. 1. Printing Characteristics Printing was performed using a card printer P-400CII (manufactured by Canon Aptex) which performs ultra-high-speed printing using a line head as a recording device. The size of the sample to be printed is 99 x 150 mm because the printer is a card printer
It went in size. The following properties were evaluated for the printed matter obtained by this printing operation and printing.

1) Ink Absorption Solid printing from single color to four colors was performed using the above printer. The ink dryness on the surface of the recording medium immediately after printing was examined by touching the recording portion with a finger to check the ink absorbency. The ink amount in solid color printing was set to 100%. Ink amount 30
0% (mixing of three colors) and no ink attached to the finger
When the ink amount was 200% (mixing of two colors) and the ink did not adhere to the finger, ○ was given, when the ink amount was 100% and the ink did not adhere to the finger, and Δ was given when the ink was attached to the finger at 100%.

2) Image Density The image density of an image solid-printed with Y, M, C, and Bk inks at a 100% ink amount using the above printer was evaluated using a Macbeth reflection densitometer RD-918.

3) Solid uniformity, bleeding, beading,
Repelling, strike-through The solid uniformity, bleeding, beading, and repelling of a recording portion in which a square pattern of 10 mm × 10 mm was solid-printed with a single color or multiple colors by the above printer were visually evaluated.
If the density of the solid portion was uniform, it was evaluated as ○. If there was no bleeding of the coloring material from the printed portion, it was evaluated as ○, and if bleeding of the coloring material was seen, it was evaluated as ×. Similarly, when no solid printed portion had beading or repelling, it was evaluated as 、, and when it occurred, it was evaluated as ×. The back surface of the recording medium was observed, and the strike-through of the coloring material was visually examined. When no strike-through was observed, it was evaluated as 、, and when it was observed, as ×.

4) Curl After Printing The above printer was used to print a 50 mm × 50 mm square pattern in the center of the recording medium in a single color of 100%. It was left on a flat table and the amount of warpage was measured with a height gauge. ○: Warp of 1mm or less, 3m over 1mm
Less than m was rated as Δ, and 3 mm or more was rated as x.

5) Tack after Printing A solid pattern of 100% single color was printed on a square pattern of 10 mm × 10 mm by the above printer. When the surface of the recording medium was touched with a finger and was not adhered, it was evaluated as O, and when adhered, it was evaluated as X.

6) Powder drop after printing 10 recording media are stacked and conveyed by the above-mentioned printer.
The powder loss of each of the 0 sheets was visually observed. If no powder was removed, it was evaluated as ○, and if powder was generated, it was evaluated as ×.

7) Sticking after Printing A 50 mm × 50 mm square pattern was printed solidly in the center of the recording medium with a single color of 100% using the above printer. Printing was continuously performed on 10 sheets, and the print samples were overlapped. Each sample was evaluated as と も when no sticking occurred, and as X when sticking occurred.

8) Surface Change after Printing (Swelling, Cockling, Wrinkling, Deformation) Using the above printer, a 50 mm × 50 mm square pattern was printed solidly at the center of the recording medium with a single color of 100%. The surface of the recording medium immediately after printing was visually observed. If there was no change or deformation on the printed surface, it was evaluated as 、. 9) Surface resistance of recording medium In an environment of 25 ° C and 50% RH, the surface resistance of the recording medium was measured with a surface resistance measuring device.

2. Liquid absorption speed A liquid is brought into contact with a sample using a dynamic scanning liquid absorption meter (KM350-D1, trade name, manufactured by Kyowa Seiko Co., Ltd.) to determine the liquid absorption amount. The liquid absorption amount was measured in the range of about 10 milliseconds to 10 seconds of the contact time, and the liquid absorption curve was obtained by taking the square root of the contact time on the horizontal axis and the liquid transfer amount on the vertical axis.

As a liquid to be measured, an aqueous ink having the following composition was used.

Aqueous ink composition (100 parts in total) Dye (CI Food Black 2): 3 parts Surfactant (Surfinol 465, manufactured by Nissin Chemical Co., Ltd.): 1 part Diethylene glycol: 5 parts Polyethylene glycol: 10 parts Ion-exchanged water: balance (Example 1) Commercially available LBKP as a raw material pulp was beaten with a double disc refiner to obtain 300 ml of Canadian Standard Freeness (CSF) beaten raw material (A). Similarly, commercially available LBKP was beaten with the same apparatus as the base layer to obtain 450 ml of the beaten raw material (B). The beating raw material (A) and the beating raw material (B) were mixed at a dry weight ratio of 9: 1 to prepare a papermaking raw material.

Alumina hydrate having a boehmite structure described in Example 1 of JP-A-9-99627 was dispersed in ion-exchanged water to prepare an alumina hydrate dispersion having a solid content of 10% by weight. . As a cationic resin, WISTEX H-90 (trade name, manufactured by Nagase Kasei Kogyo Co., Ltd., active ingredient 45%) was mixed with ion-exchanged water to prepare a cationic resin dispersion having an active ingredient amount of 10% by weight. The on-machine coating liquid was prepared by mixing the alumina hydrate dispersion and the cationic resin dispersion at a ratio of 1: 1.

Using the above-mentioned papermaking raw material, a basis weight of 8
The paper was adjusted to 0 g / m ² , and the amount of the on-machine coating solution was 4 g / m ² (alumina hydrate 2 g / m ² , cationic resin 2 g / m ² ) per one side using a two-roll size press. And the surface was smoothed with a super calender to obtain a recording medium. The feel was the same as plain paper. Table 1 shows the physical property values of the recording medium.

Example 2 Crosslinked pulp having a twisted structure as a bulky cellulose fiber (High Bulk)
Additive (trade name, manufactured by Waferwather Paper Co., Ltd.) to obtain a beating raw material (C). Raw material for beating (A)
And the beating raw material (C) were mixed at a ratio of 9: 1 in terms of a dry weight ratio to prepare a papermaking raw material. The paper was made using the same paper machine as in Example 1 so as to have the same basis weight as in Example 1.
The same amount of coating as in Example 1 was performed in the same manner as in Example 1 using the same on-machine coating liquid. A recording medium was obtained by performing a smoothing process in the same manner as in Example 1. The feel was the same as plain paper. Table 1 shows the physical property values of the recording medium.

(Example 3) According to the method described in Example 1 of JP-A-8-284090, C.I. S.
F. 300 ml of beaten pulp slurry was refined with an abrasive plate rubbing device. Next, ultrafine processing was performed using a high-pressure homogenizer to obtain a beating raw material (D) composed of fibrillated cellulose. Raw material for beating (A) and raw material for beating (D)
Was mixed at a ratio of 9: 1 in terms of a dry weight ratio to prepare a papermaking raw material. The paper was made using the same paper machine as in Example 1 so as to have the same basis weight as in Example 1, and the same amount as in Example 1 using the same on-machine coating liquid as in Example 1 in the same manner as in Example 1. Coating was performed. A recording medium was obtained by performing a smoothing process in the same manner as in Example 1. The feel was the same as plain paper. Table 1 shows the physical property values of the recording medium.

(Example 4) The beating raw material (A), the beating raw material (C) and the beating raw material (D) were converted to a dry weight ratio of 8: 1: 1.
To prepare papermaking raw materials. The paper was made using the same paper machine as in Example 1 so as to have the same basis weight as that in Example 1, and the same on-machine coating liquid as in Example 1 was used in Example 1.
The same amount coating as in Example 1 was performed in the same manner as in Example 1. Example 1
A recording medium was obtained by performing a smoothing process in the same manner as in the above. The feel was the same as plain paper. Table 1 shows the physical property values of the recording medium.

[0082]

【table 1】

[0083]

The typical effects of the present invention are as follows. 1) Good ink absorbency without sticking or set-off can be obtained even when printing is performed with an ultra-high-speed machine using a full line head or the like. 2) Even when high-speed printing is performed, the color material is separated at a high speed on the surface of the recording medium, so that good color developability and dot reproducibility are obtained, and no strikethrough occurs. 3) Since the recording medium of the present invention has a single-layer structure, it can be easily manufactured and has good productivity. 4) Since the alumina hydrate and the cationic resin are applied on-machine, they can be easily produced on a normal paper machine. The productivity is better than the conventional manufacturing method of winding and coating once.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a state of a surface of a recording medium of the present invention.

[Explanation of symbols]

 1 fiber 2 gap between fibers 3 alumina hydrate

Claims (14)

[Claims] 1. A recording medium comprising a non-sized single-layer fibrous structure mainly containing a fibrous substance and containing no filler, and having a surface formed by the single-layer fibrous structure as an ink receiving surface. A recording medium characterized in that an alumina hydrate having a boehmite structure and a cationic resin are present at least near the surface of the fibrous substance. 2. The recording medium according to claim 1, which is used for ink jet. 3. The method according to claim 1, wherein a gap exists between the fibrous substances contained in the single-layer fibrous structure, and the alumina hydrate and the cationic resin do not exist in the gap. Recording medium according to the above. 4. The recording medium according to claim 1, wherein the alumina hydrate and the cationic resin are present in contact with a surface of the fibrous substance. 5. The recording medium according to claim 1, wherein the recording medium is in the form of a sheet, and the applied amount of the alumina hydrate and the cationic resin is 1 to 5 g / m ² per one side. Recording medium. 6. The recording medium according to claim 1, wherein said alumina hydrate and said cationic resin are applied by on-machine coating. 7. The recording medium according to claim 1, wherein the single-layer fibrous structure includes a bulky or porous cellulose fiber. 8. The recording medium according to claim 7, wherein the cellulose fibers include at least one cellulose selected from mercerized cellulose, fluffed cellulose, bulky cellulose, and mechanical pulp. 9. The monolayer fibrous structure is selected from microfibrillated cellulose, sulfate pulp made from hardwood or softwood, sulfite pulp, soda pulp, hemicellulase-treated pulp, and enzyme-treated chemical pulp. The recording medium according to any one of claims 1 to 6, comprising at least one of the following. 10. The method for producing a recording medium according to claim 1, wherein the substrate having a single-layer fibrous structure mainly composed of a fibrous substance and containing no filler is provided with a boehmite structure. A method for producing a recording medium, comprising a step of applying an alumina hydrate having the formula (I) and a cationic resin. 11. The method according to claim 10, wherein the step of applying the alumina hydrate and the cationic resin to the base material is performed by on-machine coating. 12. An image forming method in which ink droplets are applied to an ink receiving surface of a recording medium to perform printing, wherein the recording medium according to claim 1 is used as the recording medium. An image forming method comprising: 13. The image forming method according to claim 12, wherein the application of the ink droplets to the recording medium is performed by ejecting small droplets of the ink from the fine holes and applying the ink droplets to the recording medium. 14. The method according to claim 12, wherein the discharging of the ink droplets is performed by applying thermal energy to the ink.
Or the image forming method according to item 13.