JP2003170652A - Medium to be inkjet-recorded and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a medium to be inkjet-recorded having a high luster, a high ink absorbency and excellent image coloring properties and also being excellent in the adhesion of a coating layer, and its manufacturing method. <P>SOLUTION: In the medium to be inkjet-recorded, in which an inorganic super fine particle-containing ink accepting layer coating liquid is applied onto a priming layer provided on a support, the priming layer includes a salt of an alkaline earth metal and an adhesive, which is 0.05 or more and 0.8 or less in the mass ratio of the salt of the alkaline earth metal. The preferable alkaline earth metal is calcium or magnesium and the preferable salt of the alkaline earth metal is a carbonate. Further, the preferable inorganic super fine particle is an amorphous synthetic silica by a gas phase method or an alumina compound. Furthermore, as the manufacturing method of the medium to be inkjet- recorded, an ink accepting layer is provided through a hot calendaring treatment after the coating of the priming layer. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording medium and a method for producing the same, and more specifically, it provides an undercoat layer on a support and an ink receiving layer coating containing inorganic ultrafine particles thereon. It is made by applying a working fluid,
The present invention relates to an inkjet recording medium having a coating layer with good adhesiveness, high gloss and high absorbency, and excellent image colorability.

[0002]

2. Description of the Related Art The ink jet recording system is a system in which minute droplets of ink are ejected by various operating principles and adhered to a recording medium such as paper to record images, characters, etc., but at high speed and low speed. It has features such as noise, easy multicoloring, great flexibility in recording patterns, and no need for development-fixing.
As a recording device for various figures and color images including kanji, it is rapidly spreading in various applications. Furthermore, the image formed by the multicolor ink jet method is more than the image formed by the multicolor printing by the plate making method or the printing by the color photographic method.
It is possible to obtain a comparable record. In addition, in applications requiring a small number of copies, it is being widely applied to the field of full-color image recording because it is cheaper than the photographic technique.

Further, as the applications are diversified, they are often used for large-sized posters, POP arts, drawing applications and the like. In these applications, the high sharpness of the ink jet is utilized, and the excellent color property allows the formation of a good image, and the advertising effect is great. The application to these is because it is possible to easily obtain an image with excellent image reproducibility and color reproducibility such as sharpness and color on a personal computer level, which is also a reason for using a large amount of inkjet recording medium. There is.

Due to the high performance of these ink jet recording apparatuses and the diversification of their uses, the characteristics and requirements required for ink jet recording media have become considerably high. In particular, in a recording device that has a high definition of an image and a recording device that is capable of large-format printing, the amount of ink used for forming an image is considerably increased compared to the conventional one, and an ink receiving layer for absorbing the ink is used. Is being improved.

In addition, the diversification of uses has spread to the appearance of ink jet recording media, and in addition to the conventional non-glossy or low-glossy appearance of plain paper or matte paper, art paper, coated paper, cast paper, etc. An appearance having a gloss similar to that of coated paper and photographic paper is required. This is because ink jet recording can reproduce image quality comparable to that of printing or photography, and thus it is desired to have a similar appearance.

Therefore, as an ink jet recording medium having a glossy surface, there is a cast coated paper obtained by cast finishing while the coating layer is in a wet state.
Although disclosed in Japanese Patent No. 20857, the surface gloss is extremely low as compared with silver salt photographic printing paper, and the texture of silver salt photographic is not obtained.

On the other hand, as an ink jet recording medium having an improved surface gloss, there is proposed a medium having an ink receiving layer made of a resin on a support. Examples of resins used for such applications include, for example, JP-A-57-381.
Nos. 85, 62-184879, and the like, polyvinylpyrrolidone, vinylpyrrolidone-vinyl acetate copolymer, JP-A-60-168651, JP-A-60-171143, and JP-A-61-134290. Disclosed in JP-A-60-234879, copolymers of vinyl alcohol and olefins or styrene and maleic anhydride, disclosed in JP-A-61-7487.
No. 9, a cross-linked product of polyethylene oxide and isocyanate, a mixture of carboxymethyl cellulose and polyethylene oxide disclosed in JP-A-61-181679, and JP-A-61-132.
A polymer obtained by grafting methacrylic acid amide onto polyvinyl alcohol disclosed in Japanese Patent No. 377, an acrylic polymer having a carboxyl group disclosed in Japanese Patent Laid-Open No. 62-220383, Japanese Patent Laid-Open No. 2143/1992.
No. 82, etc., and polyvinyl acetal-based polymers, JP-A-4-282282, 4-2828.
Various ink-absorbing polymers such as the crosslinkable acrylic polymer disclosed in Japanese Patent No. 5650 are disclosed.
Further, JP-A-4-282282 and JP-A-4-2856.
No. 50, etc. disclose an inkjet recording medium in which a polymer matrix composed of a crosslinkable polymer and an absorptive polymer are used in combination. However, the ink receiving layer made of these resins has drawbacks that it has a slower absorption speed and a smaller absorption capacity, although it has surface glossiness, as compared with the ink receiving layer made of fine pigment particles such as silica.

As an ink jet recording medium having a high ink absorption rate and a high surface gloss, an ink jet recording medium using alumina hydrate (cationic alumina hydrate) has been proposed in recent years. For example, JP-A-6
No. 0-232990, No. 60-245588, Japanese Patent Publication No. 3-24906, and Japanese Patent Laid-Open No. 6-1990.
No. 35 and No. 7-82694 disclose an inkjet recording medium in which a fine pseudo-boehmite alumina hydrate is coated on the surface of a support together with a water-soluble adhesive. However, the ink jet recording medium using the pseudo-boehmite-type alumina hydrate has a very high surface gloss, but has a small pore volume. Therefore, it is described in, for example, JP-A-5-24335. In addition, the ink absorption capacity is small, and thick film coating is necessary to obtain a sufficient ink absorption capacity.

Further, for example, in JP-A-10-203006 and 8-174992, the primary particle size is 3
Ink jet recording media using synthetic silica mainly by a vapor phase method having a size of 30 nm to 30 nm are disclosed. Also in this case, in order to obtain a sufficient absorption capacity, 30 μm
The above film thickness is required. Furthermore, JP-A-11-4
In 8602, a first ink absorbing layer containing a hydrophilic adhesive and solid fine particles in a mass ratio of 0.5 to 2.5 times that of the hydrophilic adhesive and a dry film thickness of 5 to 30 μm are disclosed. Therefore, an inkjet recording medium provided with a void layer containing fine particles having an average particle diameter of 100 nm or less is disclosed. However, in this configuration, in order to obtain sufficient ink absorbency, it is necessary to make the void layer thick, and if it is made thick, defects such as cracks occur, and in order to balance them, the first
It was necessary to increase the amount of adhesive in the ink absorption layer of
This first ink absorption layer does not contribute to the improvement of ink absorption.

On the other hand, there is also a proposal to improve the sharpness of an image by devising a support provided with an ink receiving layer. For example, JP-A-62-162588 discloses a whiteness of 90
An inkjet recording medium having a sheet whiteness of 90% or more, which comprises bleached pulp of 100% or more and an absorbent filler, is disclosed. However, although this method provided sufficient whiteness and absorption, it was not possible to obtain a high-quality glossy image. Further, JP-A No. 11-129613 discloses a recording sheet provided with a layer containing solid fine particles having a fluorescent whitening effect. However, this method is not preferable because it requires the step of forming a layer containing a special component and the addition of a special component to the ink receiving layer, which complicates the manufacturing process.

Further, JP-A-4-204727 and JP-A-4-296745 disclose resin-coated photographic supports having improved whiteness. However, the purpose of these technologies is to make photographic printing paper, and since the paper is coated with resin, the ink absorption capacity is small, and thick film coating of the ink receiving layer is necessary to obtain sufficient ink absorption capacity. is there. Further, in JP-A-2000-33771, a base paper having a layer containing barium sulfate and thermoplastic hollow fine beads on at least one surface is made of polyvinyl alcohol, polyvinyl pyrrolidone, and a vinyl acetate-butyl acrylate copolymer. An ink jet recording medium coated with an ink receiving layer is disclosed. However, since the ink receiving layer is a resin, it has a drawback that the absorption speed is slow and the absorption amount is small, although surface glossiness is obtained as compared with the ink receiving layer made of pigment fine particles such as silica.

[0012]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide an ink jet recording medium having high gloss, high ink absorbency, excellent image colorability, and no problem in the adhesiveness of an ink receiving layer, and a method for producing the same. Is provided.

[0013]

SUMMARY OF THE INVENTION The present invention comprises:
An ink jet recording medium comprising an undercoat layer and an ink receiving layer coating liquid containing inorganic ultrafine particles coated thereon, wherein the undercoat layer comprises an alkaline earth metal salt and an alkaline earth metal salt. On the other hand, the mass ratio is 0.05 times or more.
An inkjet recording medium characterized by containing 8 times or less adhesive.

The alkaline earth metal is preferably calcium or magnesium, and the salt of the alkaline earth metal is more preferably a carbonate.

The inorganic ultrafine particles are preferably amorphous synthetic silica or alumina compound by a vapor phase method.

The coating liquid for the ink receiving layer containing inorganic ultrafine particles preferably has a pH of 5.0 or less.

It is a preferable embodiment that the undercoat layer contains an adhesive in a mass ratio of 0.05 to 0.4 times the mass of the alkaline earth metal salt.

Further, in an ink jet recording medium obtained by providing an undercoat layer on a support, and coating an ink receiving layer coating solution containing inorganic ultrafine particles on the undercoat layer, the undercoat layer comprises an alkaline earth metal. Inorganic after containing a salt and an adhesive in a mass ratio of 0.05 times to 0.8 times the weight of the salt of the alkaline earth metal, and after providing the undercoat layer, a heat calendar treatment is performed. A method for producing an inkjet recording medium, which comprises an ink receiving layer containing ultrafine particles.

In the method for producing an ink jet recording medium, the inorganic ultrafine particles are amorphous synthetic silica by a vapor phase method or an alumina compound, and the pH of the ink receiving layer coating liquid is 5.0 or less. There is a preferred embodiment.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The ink jet recording medium of the present invention and the method for producing the same will be described in detail below.

The ink jet recording medium of the present invention comprises an undercoat layer provided on a support and an ink receiving layer containing inorganic ultrafine particles provided thereon.

The undercoat layer of the present invention contains a salt of an alkaline earth metal. The alkaline earth metal referred to in the present invention is a general term for beryllium, calcium, magnesium, strontium, barium, and radium. Examples of the alkaline earth metal salt include carbonate, silicate, borate,
Hydrochloric acid salts, sulfuric acid salts, organic acid salts and the like can be mentioned, but since the coating liquid for the undercoat layer is often aqueous, a weak acid salt having low solubility is preferable. Particularly preferred is calcium carbonate or magnesium carbonate.

The undercoat layer containing an alkaline earth metal salt used in the present invention contains an adhesive in an amount of 0.05 to 0.8 times the mass of the alkaline earth metal salt. It is preferable. More preferably, the range is 0.05 times or more and 0.4 times or less. If the mass ratio of the adhesive to the alkaline earth metal salt is less than 0.05, the adhesive strength is insufficient and peeling occurs between the support and the ink receiving layer. If the mass ratio of the adhesive to the alkaline earth metal salt exceeds 0.8 times, the absorptivity is lowered, which is not preferable.

Examples of the adhesive contained in the undercoat layer include cellulosic adhesives such as methyl cellulose, methyl hydroxyethyl cellulose, methyl hydroxypropyl cellulose, and hydroxyethyl cellulose, starch and its modified products, gelatin and its modified products, casein,
Natural polymers such as pullulan, gum arabic, and albumin or their derivatives, polyvinyl alcohol and its modified products, styrene-butadiene copolymer, styrene-acryl copolymer, methyl methacrylate-butadiene copolymer, ethylene-acetic acid Examples thereof include latexes and emulsions such as vinyl copolymers, vinyl polymers such as polyacrylamide and polyvinylpyrrolidone, polyethyleneimine, polypropylene glycol, polyethylene glycol, and maleic anhydride or copolymers thereof. Preferred is a copolymer emulsion.

Further, as other additives, cationic dye fixing agents, pigment dispersants, thickeners, fluidity improvers, viscosity stabilizers, pH adjusters, surfactants, defoamers, defoamers, Release agents, foaming agents, penetrants, coloring dyes, coloring pigments, white inorganic pigments, white organic pigments, fluorescent whitening agents, ultraviolet absorbers, antioxidants, leveling agents, preservatives, anti-bacterial agents, water resistant agents. ,
A wet paper strength enhancer, a dry paper strength enhancer and the like may be appropriately added within a range not impairing the object of the present invention.

The method of coating when the undercoat layer is provided is not particularly limited, and a known coating method can be used. For example, air knife coater, curtain coater, slide lip coater, die coater, blade coater, gate roll coater, bar coater, rod coater, roll coater, bill blade coater,
It can be coated on the support by various devices such as a short dwell blade coater and a size press.

The applied undercoat layer may be smoothed by calendering. Examples of the calendar processing device at that time include a gloss calendar, a super calendar, and a soft calendar. In particular, a thermal calendering treatment for smoothing while applying heat is preferably used.

The coating amount of the undercoat layer is not particularly limited,
If the amount is too small, the effect of the undercoat layer does not appear, and if the amount is too large, not only many manufacturing difficulties but also the effect is saturated, resulting in poor economy. Therefore, the preferable range is 5 g / m ² or more and 30 g.
/ M ² or less.

The inorganic ultrafine particles in the ink jet recording medium of the present invention have a primary particle diameter of 100 nm or less,
In addition, it refers to inorganic fine particles having a secondary particle diameter of 400 nm or less,
For example, JP-A-1-97678 and JP-A-2-2755.
No. 10, JP-A 3-281383, and JP-A 3-285.
No. 814, No. 3-285815, No. 4-92.
No. 183, No. 4-267180, No. 4-27.
Pseudo-boehmite sol, which is an alumina hydrate disclosed in Japanese Patent No. 5917, etc., Japanese Patent Laid-Open Nos. 60-219083, 61-19389, and 61-188183.
JP-A-63-178074 and JP-A-5-51
Colloidal silica described in Japanese Patent No. 470, etc.,
Japanese Examined Patent Publication No. 4-19037, JP-A-62-28678.
Silica / alumina hybrid sols described in JP-A No. 7-119423, JP-A-10-119423 and JP-A-10-119423.
No. 217601, silica sol in which vapor phase silica is dispersed by a high-speed homogenizer, and other smectite clays such as hectite and montmorillonite (JP-A-7-81210), zirconia sol,
Typical examples include chromia sol, yttria sol, ceria sol, iron oxide sol, zircon sol, antimony oxide sol and the like.

Among these inorganic ultrafine particles, vapor phase method silica ultrafine particles and alumina compound (alumina hydrate or aluminum oxide ultrafine particles) can be preferably used.

The silica fine particles are SiO ₂ 93 on a dry basis.
%, Al ₂ O ₃ about 5% or less, Na ₂ O about 5% or less, so-called white carbon,
There are amorphous silicas such as silica gel and finely divided silica.
As a method for producing amorphous silica fine particles, there are a liquid phase method, a pulverized solid phase method, a crystallization solid phase method and a vapor phase method. What is the liquid phase method?
This is a method for producing fine particles in which a so-called silicic acid compound or the like existing in a liquid is precipitated in a solid state by a chemical change or a physical change. The crushing solid phase method is a method of mechanically crushing silica solid, and the crystallization solid phase method is a method of producing fine particles utilizing melting or phase transition of solid. The vapor phase method is a method for producing fine particles by thermal decomposition of vapor of a volatile metal compound, heating and evaporation of raw materials, cooling of generated vapor phase species, and condensation.

The silica fine particles used in the present invention are, among the above, amorphous silica fine particles synthesized by a vapor phase method. Above all, ultrafine particle silica having an average primary particle diameter of 3 nm to 50 nm is preferable. Particularly preferred primary particle size is 5n
m to 30 nm. The secondary particle diameter in which these are connected is preferably 10 nm to 400 nm. Aerosil (Tegusa Co.) is a commercially available product as the amorphous silica fine particles synthesized by the vapor phase method.

The vapor-phase method silica used in the present invention has an average secondary particle diameter of 400 nm or less obtained by adding silica fine particles having the above-mentioned primary particle diameter to water and dispersing them with a high speed homogenizer or the like.
It is preferably dispersed up to 200 nm or less.

The alumina hydrate used in the present invention can be represented by the following general formula. Al ₂ O ₃ · nH ₂ O alumina hydrate is classified into gypsite, vialite, norstrandite, boehmite, boehmite gel (pseudo-boehmite), diaspore, amorphous amorphous, etc., depending on the difference in composition and crystal form. It In particular, in the above formula, when the value of n is 1, it represents a boehmite structure alumina hydrate, and when n is more than 1 and less than 3, it represents a pseudo-boehmite structure alumina hydrate, and n is A value of 3 or more represents an alumina hydrate having an amorphous structure. Particularly preferred alumina hydrate for the present invention is a pseudo-boehmite structure alumina hydrate in which at least n is more than 1 and less than 3.

The shape of the alumina hydrate used in the present invention may be any of tabular, fibrous, acicular, spherical, rod-like and the like, and the preferable shape is tabular from the viewpoint of ink absorbability. Flat alumina hydrate has an average aspect ratio of 3
The average aspect ratio is 3 to 6. Aspect ratio is "diameter" of "thickness" of particles
It is expressed by the ratio of. Here, the particle diameter means the diameter of a circle that is equal to the projected area of the particle when observing the alumina hydrate with an electron microscope. When the aspect ratio is smaller than the above range, the pore size distribution of the ink receiving layer becomes narrow, and the ink absorbency is lowered. On the other hand, when the aspect ratio exceeds the above range, it becomes difficult to prepare the alumina hydrate by aligning the particles.

The alumina hydrate used in the present invention can be produced by a known method such as hydrolysis of aluminum alkoxide such as aluminum isopropoxide, neutralization of aluminum salt with alkali, hydrolysis of aluminate. . In addition, the physical properties such as the particle size, pore size, pore volume, and specific surface area of the alumina hydrate should be controlled by the conditions such as precipitation temperature, aging temperature, aging time, liquid pH, liquid concentration, and coexisting compounds. You can

A method for obtaining alumina hydrate from alkoxide is disclosed in JP-A-57-88074 and JP-A-62-88074.
56321, JP-A-4-275917, 6-64918, 7-10535 and 7
-267633, U.S. Pat. No. 2,656,321
It is disclosed as a method for hydrolyzing aluminum alkoxide in the specification. Examples of these aluminum alkoxides include isopropoxide and 2-butoxide.

Further, Japanese Patent Laid-Open No. 54-116398,
No. 55-23034, No. 55-27824, and No. 56-120508 disclose methods of using an inorganic salt of aluminum or a hydrate thereof as a raw material. Examples of the raw material include inorganic salts such as aluminum chloride, aluminum nitrate, aluminum sulfate, polyaluminum chloride, ammonium alum, sodium aluminate, potassium aluminate and aluminum hydroxide, and hydrates thereof.

Still another method is disclosed in JP-A-56-120.
No. 508 discloses a method of alternately varying the pH from acidic to basic to grow crystals of alumina hydrate, and in Japanese Examined Patent Publication No. 4-33728, alumina water obtained from an inorganic salt of aluminum. A method of mixing a hydrate and alumina obtained by the Bayer method to rehydrate the alumina is disclosed.

The ink jet recording medium of the present invention comprises:
Commercially available alumina hydrate can also be preferably used. An example thereof will be given below, but the present invention is not limited thereto. For example, as the alumina hydrate, cataloid AS-1, cataloid AS-2, cataloid AS-
3 (above, produced by Catalysis Chemical Industry), alumina sol 100, alumina sol 200, alumina sol 520 (above produced by Nissan Chemical Industry), M-200 (above, produced by Mizusawa Chemical Industry), aluminum sol 10, aluminum sol 20, aluminum sol 132, aluminum sol 132S. , Aluminum sol SH5, aluminum sol CS
A55, Aluminum sol SV102, Aluminum sol SB52
(Above, manufactured by Kawaken Fine Chemicals) and the like.

As the aluminum oxide (hereinafter referred to as alumina) ultrafine particles used in the present invention, γ-type alumina fine particles which are γ-type crystals are preferably used. Crystallographically classifying γ-type crystals can be further divided into γ group and δ group. Fine particles having a crystal form in the δ group are preferred.

In the γ-type alumina fine particles, the average particle size of the primary particles can be reduced to about 10 nm, but in general, the primary particles have a secondary aggregation form (hereinafter referred to as secondary particles). Once formed, the particle size increases from thousands to tens of thousands of nanometers. When γ-type alumina fine particles having such a large particle size are used, the ink-receiving layer has good printability and absorptivity, but lacks transparency and tends to cause coating film defects. The average particle size of the primary particles is preferably less than 80 nm. When secondary particles composed of primary particles of 80 nm or more are used, brittleness increases and coating film defects are very likely to occur.

To obtain a γ-type alumina fine particle sol, normally, γ-type alumina crystals, which are secondary particles of several thousands to tens of thousands nm, are averaged by a pulverizing means such as a bead mill, an ultrasonic homogenizer, or a high pressure homogenizer. Particle size is 2
It is pulverized until it becomes ultrafine particles of 00 nm or less, preferably 100 nm or less. If the average particle size exceeds 200 nm, the ink absorbency increases, but the coating becomes brittle and the transparency decreases. As a pulverizing means, a method using an ultrasonic homogenizer or a high-pressure homogenizer is preferable, and in other pulverizing methods such as a bead mill, since the γ-type alumina crystal is a hard crystal, foreign matter is easily mixed from the pulverizing container, and the transparency is high. Cause deterioration of the product and the occurrence of defects. γ-type alumina fine particles have excellent ink absorbency, good print quality such as drying property and ink fixing property, and by being made into ultrafine particles, inkjet recording with excellent transparency even when contained in a high proportion in the ink receiving layer. The medium can be obtained.

Γ-type alumina fine particles are commercially available as δ
It is available as aluminum oxide C (manufactured by Nippon Aerosil Co., Ltd.) belonging to the group, AKP-G015 (manufactured by Sumitomo Chemical Co., Ltd.) belonging to the γ group, and the like.

A water-soluble or water-insoluble polymer compound may be added as an adhesive for the inorganic ultrafine particles used in the present invention. The polymer compound used in the present invention is a compound having an affinity for ink as a constituent component of the ink receiving layer. For example, as the water-soluble polymer compound, a cellulose-based adhesive such as methyl cellulose, methyl hydroxyethyl cellulose, methyl hydroxypropyl cellulose, and hydroxyethyl cellulose, starch and its modified products, gelatin and its modified products, casein, pullulan, gum arabic, and Natural polymer resins such as albumin or their derivatives, polyvinyl alcohol and its modified products, styrene-butadiene copolymer, styrene-acryl copolymer, methyl methacrylate-butadiene copolymer, ethylene-vinyl acetate copolymer, etc. Latex and emulsions, vinyl polymers such as polyacrylamide and polyvinylpyrrolidone, polyethyleneimine, polypropyleneglycol, polyethyleneglycol, and maleic anhydride or its co-weight Like the body or the like.
Preferred is polyvinyl alcohol.

As the water-insoluble polymer compound, an alcohol such as ethanol or 2-propanol or a water-insoluble adhesive soluble in a mixed solvent of these alcohols and water stabilizes the dispersion of alumina. Therefore, it is particularly preferable. Examples of such water-insoluble adhesives include acetal resins such as vinylpyrrolidone / vinyl acetate copolymer, polyvinyl butyral, and polyvinyl formal, and the degree of acetalization is particularly in the range of 5 mol% to 20 mol%. The acetal resin is preferable because it can contain a small amount of water and can facilitate dispersion of the inorganic ultrafine particles.

These polymer compounds may be used alone or in combination of two or more, and are 2% by mass or more and 5% by mass or more with respect to the inorganic ultrafine particles.
It is preferable to add 0 mass% or less. More preferably, 5% by mass or more and 30% by mass or less is added. If the addition amount is less than the above range, the strength of the coating film will be weak, and if it exceeds the range, the ink absorbency will be lowered.

The method of applying the coating liquid in the present invention is as follows:
E bar coating, curtain coating, strado hopper coating, extrusion coating, roll coating, air knife coating,
Various coating methods such as gravure coating and rod bar coating can be adopted.

In the present invention, the layer structure of the ink receiving layer may be a single layer or a laminated structure. In the case of a laminated structure, all layers may be layers having the same composition, or may be a laminated structure with layers composed of other components.

The coating amount of the ink receiving layer containing the inorganic ultrafine particles of the present invention needs to be 5 g or more per square meter in terms of solid content, and in order to recognize the further effect of the present invention, it is preferably per square meter. 10g or more 3
It is 0 g or less. Particularly preferably, it is not less than 10 g and not more than 20 g per square meter. Although depending on the amount of voids and the like, the thickness is preferably 10 μm or more and 30 μm or less.

As a means for drying after coating, a generally known method can be used and is not limited. For example,
The method is, for example, a method of transporting heated air generated by a heat source into a warmed air blower, a method of passing it near a heat source such as a heater.

Further, the coating liquid for forming the ink receiving layer containing the inorganic ultrafine particles of the present invention and, if necessary, the adhesive is a surfactant, an inorganic pigment, a coloring dye, a coloring pigment, an ink dye fixing agent (cation). Resins, UV absorbers, antioxidants, pigment dispersants, defoamers, leveling agents, preservatives, optical brighteners, viscosity stabilizers, pH adjusters, hardeners, etc. Can be added.

In the present invention, the alkaline earth metal salt and the alkaline earth metal salt are contained in a mass ratio of 0.05 times or more and 0.8 times or more.
By providing an undercoat layer containing an adhesive less than double, by providing an ink receiving layer containing inorganic ultrafine particles on it, it has high gloss, high absorption and excellent image colorability, and An inkjet recording medium having strong adhesiveness can be obtained. It is not clear why this combination provides high gloss and high absorbency. In order to obtain high gloss, it is necessary that the ink receiving layer does not soak into the undercoat layer at the time of coating the ink receiving layer and is leveled to form a highly smooth surface and dried. And in order to obtain high absorbency, not only the ink receiving layer but also the undercoat layer must contribute to the absorption, but if the absorbency of the undercoat layer is too large, when the ink receiving layer is coated, the ink receiving layer coating is applied. The liquid penetrates into the undercoat layer, resulting in a contradiction that a high gloss cannot be obtained.

As in the present invention, when the pigment in the undercoat layer is a salt of an alkaline earth metal and the ink receiving layer coating solution is acidic, the ink receiving layer is coated with an acid when the ink receiving layer is coated. It is considered that the acid and the salt of alkaline earth metal cause a shock, and the ultrafine inorganic particles do not penetrate the undercoat layer to form a boundary surface. Then, during or after drying, the alkaline earth metal salt in the boundary surface or in the undercoat layer is gradually dissolved or deformed by water or acid in the ink receiving layer to form an absorption path to form the undercoat layer. It is considered that the absorptivity is linked to the voids of the ink receiving layer and enhances the absorptivity. Therefore, the ink receiving layer coating liquid is preferably in the acidic region. The pH of the ink receiving layer coating liquid is more preferably 5.0 or less, and particularly pH
It is preferably 4.0 or less. P of ink receiving layer coating liquid
When H exceeds 5.0, the interaction with the salt of the alkaline earth metal becomes weak and the ink absorbency tends to be slightly lowered.
Further, in the alkaline region, the effect hardly appears.

The support used in the present invention is not particularly limited as long as it is a support on which the undercoat layer and the ink receiving layer can be coated, but a paper support is preferably used. As the pulp that constitutes the paper that is preferably used,
One kind or a mixture of two or more kinds of natural pulp, recycled pulp, synthetic pulp and the like is used. As the natural pulp, any pulp commonly used for papermaking, that is, bleached chemical pulp such as softwood kraft pulp, hardwood kraft pulp, softwood sulfite pulp, and hardwood sulfite pulp can be used. Further, it may be mechanical pulp having high whiteness. In addition, straw, esparto,
Non-wood pulp produced from grass fibers such as bagasse and kenaf, bast fibers such as hemp, swordfish, goose bark, and three tsubaki, and cotton. Of these, bleached chemical pulps such as softwood kraft pulp, hardwood kraft pulp, softwood sulphite pulp, and hardwood sulphite pulp which are most commonly used industrially are particularly preferable.

The pulp is beaten by a beater such as a double disc refiner in order to improve the papermaking suitability and various properties of the paper such as strength, smoothness, and uniformity of formation. The degree of beating can be selected according to the purpose within the usual range of about 250 ml to 550 ml in Canadian Standard Freeness.

The beaten pulp slurry is paper-made by a paper machine such as a Fourdrinier paper machine, a twin wire paper machine, or a round-net paper machine. At this time, in the present invention, the pulp slurry usually used for paper making is used. Various additives such as a dispersion aid, a dry paper strength enhancer, a wet paper strength enhancer, a filler, a sizing agent, and a fixing agent can all be added as necessary. Further, if necessary, a pH adjusting agent, a dye, a colored pigment, an optical brightening agent and the like can be added.

Examples of dispersion aids include polyethylene oxide, polyacrylamide, and grated yam, and examples of paper strength agents include vegetable gum, starch, anionic paper strength enhancers such as carboxy-modified polyvinyl alcohol, cationized starch, and the like. Cationic paper strengthening agents such as cationic polyacrylamide and polyamide polyamine epichlorohydrin resin may be used as fillers such as clay, kaolin,
Talc, heavy calcium carbonate, light calcium carbonate, barium sulfate, titanium oxide, aluminum hydroxide, magnesium hydroxide and the like, as the sizing agent, for example, higher fatty acid salt, rosin, rosin derivatives such as maleated rosin, dialkyl ketene dimer, Alkenyl or alkyl succinates, epoxidized fatty acid amides, polysaccharide esters, and the like, and fixing agents include, for example, polyvalent metal salts such as aluminum sulfate and aluminum chloride, cationized starch, and cationic polymers such as polyamide polyamine epichlorohydrin resin. As the pH adjuster, hydrochloric acid, caustic soda, sodium carbonate, etc. are used.

The paper support preferably used in the present invention contains a liquid containing various additives such as a water-soluble polymer additive, a tab size, size press, gate roll coater or film transfer coater. It is also possible to coat with.

Examples of the water-soluble polymer additive include starch derivatives such as starch, cationized starch, oxidized starch, etherified starch and phosphoric esterified starch, polyvinyl alcohol derivatives such as polyvinyl alcohol and carboxy-modified polyvinyl alcohol, and the like. Carboxymethyl cellulose,
Cellulose derivatives such as hydroxymethyl cellulose, hydroxyethyl cellulose and cellulose sulfate,
Water-soluble natural polymers such as gelatin, casein, soybean protein,
Sodium polyacrylate, styrene-maleic anhydride copolymer sodium salt, sodium polystyrene sulfonate, etc., water-soluble polymer such as maleic anhydride resin, aqueous polymer such as thermosetting synthetic resin such as melamine resin, urea resin, etc. Adhesives are used, and in addition to these, as a sizing agent, a petroleum resin emulsion, a styrene-maleic anhydride copolymer alkyl ester ammonium salt, an alkyl ketene dimer emulsion, a styrene-butadiene copolymer, an ethylene-vinyl acetate copolymer. Examples include dispersions of polymers, polyethylene, polyvinylidene chloride and the like. Other additives include, as antistatic agents, inorganic electrolytes such as sodium chloride, calcium chloride, and sodium sulfate, as hygroscopic substances such as glycerin and polyethylene glycol, as pigments, clay, kaolin, talc, barium sulfate, and oxidation. Titanium or the like uses hydrochloric acid, caustic soda, sodium carbonate or the like as a pH adjusting agent, and it is also possible to use it in combination with other additives such as dyes, optical brighteners, antioxidants, and ultraviolet absorbers.

The paper support preferably used in the present invention is preferably one having good surface smoothness, such as being compressed by applying pressure with a calender during or after papermaking,
Beck's smoothness measured by JIS-P-8119 is 50.
Those of seconds or more are preferable, and those of 100 seconds or more are particularly preferable. Also, the basis weight is preferably 70~300g / m ^2, and more preferably a 150 to 300 g / m ^2.

[0062]

EXAMPLES The present invention will be described below with reference to examples. The present invention is not limited to the examples. All parts and% in the following are by mass.

<Preparation of support> A 1: 1 mixture of a bleached hardwood kraft pulp (LBKP, 90% whiteness) and a bleached softwood pulp (NBSP, 90% whiteness) was beaten to a Canadian standard freeness of 300 ml. Then, a pulp slurry was prepared. Alkyl ketene dimer as a sizing agent to 0.5% by weight of pulp, polyacrylamide as a paper strengthening agent to 1.0% by weight of pulp, cationized starch to 2.0% by weight of pulp, polyamide epichlorohydrin Resin to pulp.
5% by mass was added and diluted with water to obtain a 1% slurry. After that, the stock slurry is formed into a web using a Fourdrinier paper machine, subjected to a three-stage wet press in the wet part, treated with a smoothing roll, and then subjected to 2 in the middle of the subsequent drying part.
A dandan press was performed. Then, in the middle of drying, 20 g / m ² size press liquid of 5% by mass of carboxy-modified polyvinyl alcohol was pressed, and the base paper finally obtained was dried so that the moisture content of the base paper was 8% by mass. A paper support was prepared by calendering and making a paper having a basis weight of 170 g / m ² . The Beck's smoothness of the paper support was 110 seconds.

<Undercoat Layer Coating Liquids 1a to 1h> Light calcium carbonate (Tamapearl 22) as a salt of an alkaline earth metal.
2H: 100 parts of Okutama Kogyo Co., Ltd., styrene-butadiene copolymer latex (Lack Star DS) as an adhesive
226, manufactured by Dainippon Ink and Chemicals, Inc., in solid content of 3 parts each, 5
Parts, 10 parts, 15 parts, 20 parts, 40 parts, 80 parts, 100
Part is mixed with water to prepare an undercoat layer coating liquid 1 having a solid content concentration of 45%.
a to 1h were prepared.

<Undercoat Layer Coating Liquid 2> Heavy calcium carbonate (carbital 90: ECC) as a salt of an alkaline earth metal.
International Co., Ltd.) 100 parts, styrene-butadiene copolymer latex as an adhesive (Lack Star D
(S226, manufactured by Dainippon Ink and Chemicals, Inc.) 20 parts of solid content was mixed with water to prepare an undercoat layer coating solution 2 having a solid content concentration of 45%.

<Undercoat layer coating liquid 3> 100 parts of magnesium carbonate (spherical magnesium carbonate: manufactured by Kamijima Chemical Industry Co., Ltd.) as a salt of an alkaline earth metal, and styrene-butadiene copolymer latex (Lack Star DS22 as an adhesive).
(6, manufactured by Dainippon Ink and Chemicals, Inc.) 20 parts of solid content was mixed with water to prepare an undercoat layer coating solution 3 having a solid content concentration of 45%.

<Undercoat layer coating liquid 4> 100 parts of barium sulfate (precipitable barium sulfate D-2: manufactured by Barite Kogyo Co., Ltd.) as a salt of an alkaline earth metal, and styrene-butadiene copolymer latex (Lack Star) as an adhesive. DS22
20 parts of solid content (manufactured by Dainippon Ink and Chemicals, Inc.) was mixed with water to prepare an undercoat layer coating solution 4 having a solid content concentration of 45%.

<Undercoat layer coating liquid 5> 100 parts of synthetic amorphous silica (Fineseal X37B: manufactured by Tokuyama Corp.),
20 parts of polyvinyl alcohol (PVA117: manufactured by Kuraray Co., Ltd.) as an adhesive is dissolved and mixed in water to give a solid content of 20%.
The undercoat layer coating liquid 5 was prepared.

<Ink receiving layer coating liquid A> Primary particle diameter 7n
m of gas phase ultrafine silica (AEROSIL300: manufactured by Nippon Aerosil Co., Ltd.) and a dispersant (Charol DC)
902P: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 3 g was dispersed in 500 g of ion-exchanged water with a stirrer to obtain a secondary particle diameter of 200 nm.
The following dispersion was obtained. Further, 15 parts of an aqueous solution of 10% by mass of polyvinyl alcohol (PVA105: manufactured by Kuraray Co., Ltd.) was mixed with 100 parts of this gas phase ultrafine silica dispersion liquid, and water was added to coat an ink receiving layer having a solid content concentration of 15%. It was designated as working fluid A. The pH of the ink receiving layer coating liquid A was 3.8.

<Synthesis of alumina hydrate> Ion-exchanged water 1
200 g and 900 g of isopropyl alcohol were charged into a 3 L reactor and heated to 75 ° C. Aluminum isopropoxide (408 g) was added, and the mixture was heated at 75 ° C. for 24 hours, followed by 9
Hydrolysis was performed at 5 ° C. for 10 hours. Acetic acid 2 after hydrolysis
4 g was added and stirred at 95 ° C. for 48 hours. Then, the mixture was concentrated to a solid content concentration of 15% by mass to obtain a dispersion liquid of white ultrafine particulate alumina hydrate. When this sol was dried at room temperature and measured by X-ray diffraction, it showed a pseudo-boehmite structure. Further, the average particle size was measured with a transmission electron microscope, and it was 30 nm, and it was a tabular ultrafine particle alumina hydrate having an aspect ratio of 6.0. Also, the average pore radius, pore volume and BET are determined by the nitrogen adsorption / desorption method.
When the specific surface areas were measured, they were 7.1 nm and 0.
It was 65 ml / g and 200 m ² / g.

<Ink receiving layer coating liquid B> 15% by mass
Using a homomixer, the dispersion liquid of the ultra-fine particulate alumina hydrate is dispersed so that the secondary particle diameter is 400 nm or less. Polyvinyl alcohol (PVA10
5: Kuraray Co., Ltd.) 15 parts of an aqueous solution were mixed. This mixed liquid was concentrated by an evaporator so that the solid content concentration was 15%, and the ink receiving layer coating liquid B was obtained. The pH of the ink receiving layer coating liquid B was 4.5.

<Ink-Receptive Layer Coating Liquid C> γ-group alumina crystal powder of δ group as alumina ultrafine particles,
Aerosil aluminum oxide C with a primary particle size of 13 nm
(Japan Aerosil Co., Ltd.) 600 g in 2400 g of ion-exchanged water, using a homomixer, the secondary particle size is 10
Dispersion was performed so as to be 0 nm or less to prepare a 20% by mass slurry-like viscous liquid. Using this 20 mass% γ-type alumina dispersion, 1 part was added to 100 parts of the alumina dispersion.
0% by mass of polyvinyl alcohol (PVA2 manufactured by Kuraray Co., Ltd.
35) 30 parts of the aqueous solution were mixed. Water was added to prepare an ink receiving layer coating liquid C having a solid content concentration of 15%. The pH of the ink receiving layer coating liquid C was 5.0.

<Ink receiving layer coating liquid D> Primary particle diameter 7n
m of gas phase ultrafine silica (AEROSIL300: manufactured by Nippon Aerosil Co., Ltd.) and a dispersant (Charol DC)
902P: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 3 g was dispersed in 500 g of ion-exchanged water with a stirrer to obtain a secondary particle diameter of 200 nm.
The following dispersion was obtained. Furthermore, 15 parts of a 10 mass% polyvinyl alcohol (PVA105: Kuraray Co., Ltd.) aqueous solution was mixed with 100 parts of this gas phase ultrafine silica dispersion, and sodium hydroxide was added to adjust the pH to 5.5. Then, water was added to prepare an ink receiving layer coating liquid D having a solid content concentration of 15%.

<Ink Receptor Layer Coating Liquid E> Synthetic amorphous silica having a secondary particle diameter of 3.7 μm which does not correspond to the inorganic ultrafine particles of the present invention (Fineseal X-37B: manufactured by Tokuyama Corporation B)
ET specific surface area 270 m ² / g) 100 parts, polyvinyl alcohol (PVA105: manufactured by Kuraray Co., Ltd.) 15 parts, cationic dye fixing agent (SUMIREZ RESIN 1001: Sumitomo Chemical Co., Ltd.) 20 parts were dissolved and mixed in water to obtain a solid content. The coating liquid E was an ink receiving layer having a concentration of 15%. P of ink receiving layer coating liquid E
H was 5.3.

Example 1 On the paper support prepared above, the undercoat layer coating liquid 1b was applied.
Dry solid content 15g / m ²Air knife coater
It was applied and dried. Then, on top of the subbing layer,
The coating liquid A of the receiving layer was dried with a curtain coater to give a solid content of 1
5 g / m²The coating of Example 1 was dried by applying
The recording medium.

Example 2 A recording medium of Example 2 was obtained in the same manner as in Example 1 except that the undercoat layer coating solution 1b was replaced with the undercoat layer coating solution 1c.

Example 3 A recording medium of Example 3 was obtained in the same manner as in Example 1 except that the undercoat layer coating liquid 1b was replaced with the undercoat layer coating liquid 1d.

Example 4 A recording medium of Example 4 was obtained in the same manner as in Example 1 except that the undercoat layer coating liquid 1b was replaced with the undercoat layer coating liquid 1e.

Example 5 A recording medium of Example 5 was prepared in the same manner as in Example 1 except that the undercoat layer coating liquid 1b was replaced with the undercoat layer coating liquid 1f.

Example 6 A recording medium of Example 6 was obtained in the same manner as in Example 1 except that the undercoat layer coating liquid 1b was replaced with the undercoat layer coating liquid 1g.

Comparative Example 1 A recording medium of Comparative Example 1 was obtained in the same manner as in Example 1 except that the undercoat layer coating solution 1b was replaced with the undercoat layer coating solution 1a.

Comparative Example 2 A recording medium of Comparative Example 2 was obtained in the same manner as in Example 1 except that the undercoat layer coating solution 1b was replaced with the undercoat layer coating solution 1h.

Example 7 A recording medium of Example 7 was prepared in the same manner as in Example 1 except that the undercoat layer coating liquid 1b was replaced with the undercoat layer coating liquid 2.

Example 8 A recording medium of Example 8 was prepared in the same manner as in Example 1 except that the undercoat layer coating solution 1b was replaced with the undercoat layer coating solution 3.

Example 9 A recording medium of Example 9 was obtained in the same manner as in Example 1 except that the undercoat layer coating liquid 1b was replaced with the undercoat layer coating liquid 4.

Comparative Example 3 A recording medium of Comparative Example 3 was obtained in the same manner as in Example 1 except that the undercoat layer coating solution 1b was replaced with the undercoat layer coating solution 5.

Example 10 A recording medium of Example 10 was obtained in the same manner as in Example 3, except that the ink receiving layer coating liquid A was replaced with the ink receiving layer coating liquid B.

Example 11 A recording medium of Example 11 was obtained in the same manner as in Example 3 except that the ink receiving layer coating liquid A was replaced with the ink receiving layer coating liquid C.

Example 12 A recording medium of Example 12 was obtained in the same manner as in Example 3, except that the ink receiving layer coating liquid A was replaced with the ink receiving layer coating liquid D.

Comparative Example 4 A recording medium of Comparative Example 4 was obtained in the same manner as in Example 3 except that the ink receiving layer coating liquid A was replaced with the ink receiving layer coating liquid E.

Example 13 In Example 3, the undercoat layer was applied and dried, and then heat calendered (temperature 100 ° C., nip pressure 150 kg / c).
A recording medium of Example 13 was made in the same manner as in Example 3 except that m) was applied.

Example 14 In Example 10, the undercoat layer was applied and dried, and then heat calendered (temperature 100 ° C., nip pressure 150 kg / c).
m), and the pH of the ink receiving layer coating liquid B is adjusted to pH with hydrochloric acid.
A recording medium of Example 14 was made in the same manner as in Example 10 except that the recording medium was adjusted to 4.0.

<Evaluation of Ink Absorption> Ink absorption was evaluated by using an ink jet recording apparatus P manufactured by Epson Corporation.
Using M9000, a heavy-colored rectangular pattern was printed with cyan ink, magenta ink, and yellow ink. When the overlapping ink amount is 100% for all colors, it is set to 300%, and when all the ink amounts are 90%, it is set to 270%.
Rectangular patterns of 0%, 180% and 150% were created and printed. The bleeding state of the ink at the boundary between the printed pattern and the unprinted portion was visually evaluated according to the following criteria. ⊚: No deflation is observed at 300% printing ◯: No deflation is observed at 270% printing Δ: No deflation is observed at 210% printing ×: Deflation is observed at 180% printing Shows good ink absorption The ratings are from ⊚ to Δ.

<Evaluation of Image Colorability> Canon BJC-42
Solid printing of magenta and cyan was performed using 0J. The color was visually evaluated as follows. A: The color is good and the image looks clear. ○: The color looks good. Δ: The color looks slightly dull. X: The color is dull and dull. Good image colorability is evaluated by ⊚ or ◯.

<Evaluation of White Paper Gloss> Example 1 is standard (◯)
By visual observation, those higher than those in Example 1 were marked with ⊚, those inferior to those in Example 1 were evaluated as Δ, and those with extremely poor glossiness were marked with ×.

<Evaluation of Adhesiveness> After making a lattice-like notch at 5 mm intervals from the recording surface side with a cutter knife,
An adhesive tape was attached to the recording surface, peeled off, and the number of peeled ink receiving layers per 100 grids was judged. ◯: The number of peeled pieces is less than 10 Δ: The number of peeled pieces is 10 to 30 ×: The number of peeled pieces is 31 or more Good adhesiveness is ○, and even if Δ is practically no problem.

[0097]

[Table 1]

From Table 1, the alkaline earth metal salt and the salt of the alkaline earth metal are contained in a mass ratio of 0.05 times or more.
In Examples 1 to 14 in which the ink receiving layer containing the inorganic ultrafine particles was provided on the undercoat layer containing the adhesive of 8 times or less, the visual white paper gloss, the image colorability, and the ink absorbability were all balanced. Good and good results have been obtained. However, when the undercoat layer does not contain an alkaline earth metal salt (Comparative Example 3), the gloss and absorbency are poor, and even if the undercoat layer contains an alkaline earth metal salt, the mass ratio of the adhesive is Is less than 0.05 (Comparative Example 1), the adhesiveness is poor, and when the mass ratio of the adhesive exceeds 0.8 (Comparative Example 2), the absorptivity is poor and not practical. Furthermore, if the pigment of the ink receiving layer is not inorganic ultrafine particles (Comparative Example 4), the gloss and color are inferior. In addition, in Example 12 in which the pH of the ink receiving layer coating liquid exceeds 5.0, the ink absorbency is slightly worse than in Examples 3, 10, and 11 in which the pH is 5.0 or less.
Further, it is a preferable production method to apply a thermal calendar treatment after coating the undercoat layer (Examples 13 and 14) since the visual white paper gloss is further improved.

[0099]

As described above, according to the present invention,
It is possible to provide an inkjet recording medium having high gloss, excellent ink absorbency and image colorability, and having no problem in the adhesiveness of the coating layer.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2C056 FC06                 2H086 BA12 BA15 BA31 BA33 BA41                       BA45

Claims (9)

[Claims] 1. An ink jet recording medium comprising an undercoat layer provided on a support and coated with an ink receiving layer coating liquid containing inorganic ultrafine particles, wherein the undercoat layer comprises an alkaline earth metal. An inkjet recording medium comprising a salt and an adhesive whose mass ratio is 0.05 times or more and 0.8 times or less with respect to the salt of the alkaline earth metal. 2. The ink jet recording medium according to claim 1, wherein the alkaline earth metal is calcium or magnesium. 3. The inkjet recording medium according to claim 1, wherein the alkaline earth metal salt is a carbonate. 4. The ink jet recording medium according to claim 1, wherein the inorganic ultrafine particles are amorphous synthetic silica obtained by a vapor phase method. 5. The ink jet recording medium according to any one of claims 1 to 3, wherein the inorganic ultrafine particles are an alumina compound. 6. The ink-receiving layer coating liquid containing inorganic ultrafine particles has a pH of 5.0 or less.
6. The inkjet recording medium according to any one of items 5 to 5. 7. The undercoat layer contains an adhesive in an amount of 0.05 times or more and 0.4 times or less by mass ratio with respect to the salt of the alkaline earth metal. 2. The inkjet recording medium according to item 1. 8. An ink jet recording medium comprising an undercoat layer provided on a support and coated with an ink receiving layer coating liquid containing inorganic ultrafine particles, the undercoat layer comprising an alkaline earth metal. Inorganic after containing a salt and an adhesive in a mass ratio of 0.05 times to 0.8 times the weight of the salt of the alkaline earth metal, and after providing the undercoat layer, a heat calendar treatment is performed. A method for producing an inkjet recording medium, which comprises providing an ink receiving layer containing ultrafine particles. 9. The inorganic ultrafine particles are amorphous synthetic silica or alumina compound by a vapor phase method, and the pH of the ink receiving layer coating liquid is 5.0 or less. 8. The method for manufacturing an inkjet recording medium according to item 8.