JP3513352B2 - INK JET RECORDING MEDIUM, METHOD FOR MANUFACTURING THE SAME, IMAGE FORMING METHOD USING THE SAME, AND DISPERSION - Google Patents

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 suitable for recording with an aqueous ink, a method for producing the same, and an image forming method using the same, and more particularly, transparency of an ink receiving layer, image density and The present invention relates to an inkjet recording medium having high resolution and excellent in ink absorbing ability and film forming property, a manufacturing method thereof, and an image forming method using the same.

[0002]

2. Description of the Related Art The ink jet recording system is characterized by high speed, low noise, easy multicoloring, arbitrary setting of recording patterns, and no need for development and fixing.
2. Description of the Related Art In recent years, it has rapidly become widespread as an output device for various images in applications such as information equipment. Furthermore, images formed by the multicolor inkjet system are comparable to multicolor printing by the plate making system or printing by the color photographic system, and if the number of copies is small, it is cheaper than the conventional system. ,
It is being widely applied to the field of full-color image recording.

The recording apparatus and the recording method have been improved with the improvement of recording characteristics such as high speed recording, high definition recording, and full-color recording. However, high characteristics are also required for the recording medium. It started to come.

In response to this demand, various recording media have been proposed in the past. For example, JP-A-55-5
Japanese Patent No. 830 discloses an ink jet recording paper having a support surface provided with an ink absorbing coating layer. Further, in JP-A-55-51583, an example of using amorphous silica as a pigment in a coating layer is disclosed in JP-A-55-146.
Japanese Patent No. 786 discloses an example in which a coating layer of a water-soluble polymer is provided on a support.

US Pat. No. 4,879,166,
No. 5,104,730, JP-A-2-276670,
JP-A-4-37576 and JP-A-5-32037 propose recording media having a coating layer containing an alumina hydrate having a boehmite structure.

Recently, in order to reduce the graininess in the highlight portion of an image and obtain an image closer to a silver salt photograph, the density of the dye in the ink is reduced to about 1/2 to 1/4 of the usual density. There has been proposed an image forming method using multiple recording in which light ink is used in combination. In such an image forming method, overprinting with the same color ink is performed in order to perform multi-tone expression from highlight to shadow. Therefore, the amount of ink applied per unit area is larger than that in the conventional case, and ink overflows in the conventional recording medium. Further, as the amount of solvent component in the ink increases, the absorption speed of the ink decreases, and beading and bronzing of the printed portion occur.

The term "beading" used herein means that when the next ink dot is applied adjacent to the previous ink dot before the previously applied ink dot is fixed on the recording medium, the ink dot is laterally moved. This is a phenomenon in which the dots move irregularly and, as a result, agglomeration occurs between adjacent dots, resulting in uneven image density.

Bronzing means a phenomenon in which the ink absorption rate becomes slow and the dye in the ink aggregates and remains on the surface, whereby the printed portion is colored bronze.

Japanese Unexamined Patent Publication No. 4-67985 and Japanese Unexamined Patent Publication No. 8-
Japanese Patent No. 333115 describes that the aggregate of alumina hydrate is deflocculated into colloidal particles by adding a compound having a monocarboxylic acid or sulfonic acid group. However, such a compound having a monocarboxylic acid or sulfonic acid group alone causes excessive deflocculation and the colloidal particles of the alumina hydrate become finer. The small particles densely aggregate to reduce the ink absorption rate.

Further, JP-A-6-286297 and JP-A-6-286297.
No. 316145, No. 8-108614, and No. 8-295075 disclose inkjet recording media to which various organic acids are added to prevent bleeding and discoloration. However, adding organic acid alone
When the amount of ink applied is large as in the above-described multiplex recording, the occurrence of beading and bronze cannot be sufficiently suppressed.

[0011]

SUMMARY OF THE INVENTION The present invention has been made for the purpose of solving the above-mentioned problems, and in particular, a recording medium for improving ink absorption in multiple recording of ink and reducing beading and bronzing, The present invention provides a manufacturing method thereof, an image forming method using such a recording medium, and a dispersion suitable for manufacturing the recording medium.

[0012]

The above object can be achieved by the present invention described below.

[0013] Specifically, the present invention, there is provided a recording medium having an ink receiving layer containing an alumina hydrate and a binder on a substrate, seen containing an organic acid, wherein the ink-receiving layer includes an inorganic acid and a carboxyl group, wherein the organic Primary dissociation index pKa of acid
(O) and the primary dissociation index pKa (I) of the inorganic acid are p
Characterized by the relationship of Ka (O)> pKa (I)
It is an inkjet recording medium.

The present invention is also an image forming method characterized by using the above-mentioned recording medium as a recording medium in a method for forming an image by applying ink droplets to the recording medium.

The present invention further relates to alumina hydrate and binder.
-, Including an inorganic acid and an organic acid having a carboxyl group,
PKa (O) of the organic acid and pKa (I) of the inorganic acid
Is the relationship of pKa (O)> pKa (I), which is a dispersion liquid for forming a recording medium for inkjet. The present invention is also a method for producing a recording medium using this dispersion.

[0016]

DETAILED DESCRIPTION OF THE INVENTION As a result of intensive investigations by the present inventors, an ink receiving layer containing an alumina hydrate and a binder was formed.
Primary dissociation index pKa of organic acid having carboxyl group
(O) and the primary dissociation index pKa (I) of the inorganic acid are p
It has been found that good results can be obtained with respect to the above technical problem by including at least one inorganic acid and at least one organic acid having a carboxyl group in the relationship of Ka (O)> pKa (I) .

It is not clear why beading and bronzing can be suppressed by using an inorganic acid and an organic acid having a carboxyl group in combination, but the following reasons are considered.

By using an inorganic acid and an organic acid having a carboxyl group in combination in the dispersion of hydrated alumina, the equilibrium of the organic acid shifts to the left to suppress the dissociation of ions, as shown below.

[0019]

[Outer 1]

The organic acid liberated in the dispersion liquid interacts with the colloidal alumina hydrate by the action of the inorganic acid to form uniform and weak aggregates (flocs). Therefore, even when this dispersion is applied thickly on a base material, small particles are not densely aggregated in the vicinity of the surface, and relatively large pores are easily formed on the surface portion of the coating layer. For this reason, it is considered that the absorption speed of the ink becomes faster, the aggregation of the ink dots does not easily occur even in the multiple recording with the ink, and the beading and the bronzing can be prevented.

As the inorganic acid used in the present invention, the primary dissociation index pK in water is sufficient to deflocculate alumina hydrate and to suppress the dissociation of the carboxyl group.
It is preferable that a is 3 or less. Of these, hydrochloric acid (pKa = -7), nitric acid (pKa = -1.4) and phosphoric acid (pKa = 2.1) are particularly preferable because the ink receiving layer becomes transparent.

On the other hand, inorganic sulfonic acids such as sulfuric acid and sulfuric acid amide have an excessively high ability to insolubilize dye molecules, as described in JP-A-8-108614, so that they are not formed on the surface of the ink receiving layer. It is not preferable because the dye tends to agglomerate and the printed portion tends to bronze.

The organic acid having a carboxyl group used in the present invention preferably has a primary dissociation index pKa in water of 1 or more and 5 or less. If the pKa is less than 1, the dissociation of the carboxyl group is large and the formation of flocs is not sufficient. When the pKa exceeds 5, the liquid thickening is caused by the interaction with the alumina hydrate. Among them, especially formic acid (pKa = 3.8) and acetic acid (pKa =
4.8), chloroacetic acid (pKa = 2.9), lactic acid (pK
a = 3.9), citric acid (pKa = 3.1), oxalic acid (pKa = 1.3), maleic acid (pKa = 1.9),
Malonic acid (pKa = 2.9) is preferred.

In the present invention, the pKa (p
Ka (I)) and an organic acid having a carboxyl group pKa
(PKa (O)), characterized in Succoth satisfy the relation pKa (I) <pKa (O ). If pKa (I) ≧ pK
When it is a (O), dissociation of the organic acid is likely to occur, the flocs of the alumina hydrate are not sufficiently formed, and beading and bronzing are likely to occur.

The addition amount of the inorganic acid is preferably 1 μmol or more and less than 1000 μmol with respect to 1 g of the alumina hydrate of the solid content. If the amount added is less than 1 μmo, sufficient deflocculation of the alumina hydrate is not performed, the dispersion of the alumina hydrate in the dispersion is not sufficient, and sedimentation easily occurs. If the addition amount is 1000 μmol or more, the pH of the coating liquid is too low, and thus the tint change after printing is likely to occur.

The amount of the organic acid added is preferably 1 μmol or more and less than 1000 μmol with respect to 1 g of the solid alumina hydrate. If this addition amount is less than 1 μmo, the formation of flocs is not sufficient, and beading and bronzing are likely to occur. If the amount added exceeds 1000 μmol, the alumina hydrate will conversely agglomerate excessively in the dispersion, so that the viscosity of the dispersion tends to increase and coating becomes difficult.

The combined ratio of the inorganic acid and the organic acid is a molar ratio,
The range of inorganic acid: organic acid is preferably 10: 1 to 1:10. This ratio exceeds 10: 1 (inorganic acid increases)
As a result, the floc formation of the alumina hydrate is not sufficient, and beading and bronzing are likely to occur. If this ratio is less than 1:10 (the amount of organic acid increases), similarly beading and bronzing are likely to occur. It is considered that the reason is that the amount of the inorganic acid is small, the dissociation of the carboxyl group is large, and the formation of the flocs of the alumina hydrate is insufficient.

Alumina hydrates preferably used in the present invention include those called aluminum hydroxide and are represented by the following general formula.

Al ₂ O _3−n (OH) _2n · mH ₂ O (wherein n is an integer of 0 to 3, m is 0 to 10, and preferably 0 to 5, n and m Does not become 0 at the same time.)

In the formula, mH ₂ O often represents a detachable aqueous phase that does not participate in the formation of the crystal lattice, and therefore m can take a non-integer value. When calcining this type of alumina hydrate, m can reach a value of zero.

In the recording medium of the present invention, the binder used in combination with the above-mentioned alumina hydrate is preferably a water-soluble polymer substance. For example, polyvinyl alcohol or its cation modified product, anion modified product, silanol modified product, starch or its modified product (oxidized starch, etherified starch), gelatin or its modified product, casein or its modified product, carboxymethyl cellulose, gum arabic, Cellulose derivatives such as hydroxyethyl cellulose and hydroxypropylmethyl cellulose, SBR latex, NBR latex, conjugated diene copolymer latex such as methyl methacrylate-butadiene copolymer, functional group modified polymer latex, vinyl such as ethylene vinyl acetate copolymer Preferred are copolymer latexes, polyvinylpyrrolidone, maleic anhydride or copolymers thereof, and acrylic acid ester copolymers. These binders may be used alone or in combination of two or more.

The mixing ratio of the alumina hydrate and the binder can be arbitrarily selected in a weight ratio of preferably 1: 1 to 30: 1, more preferably 5: 1 to 20: 1. When the amount of the binder is less than the above range, the mechanical strength of the ink receiving layer is insufficient and cracking and powder drop are likely to occur. When the amount of the binder is more than the above range, the pore volume becomes small and the ink absorbency is reduced. Is easy to decrease.

When preparing the dispersion, in addition to the alumina hydrate and the binder, if necessary, a curing agent, a dispersant, a thickener, a waterproofing agent, a release agent, a foaming agent, a penetrant, a coloring dye, A fluorescent whitening agent, an ultraviolet absorber, an antioxidant, a preservative, an antifungal agent and the like can be added.

As a curing agent, Mitec SW200
Aqueous polyisocyanate compounds such as (trade name, manufactured by Mitsubishi Chemical); aqueous aziridine compounds such as Chemitite DZ-22E and PZ-33 (both are trade names, manufactured by Nippon Shokubai Kagaku Kogyo); Sumirez Resin 613 Special, 8% A
C, EU, Sumimar M-50W, M-40W, M-3
Water-soluble melamine resins such as 0W and MC-1 (both are trade names, manufactured by Sumitomo Chemical Co., Ltd.); Cymel 60, 80 (trade names, manufactured by Mitsui Cyanamid), Sumirezu 614 Special, 633 (both are trade names, Sumitomo Chemical Co., Ltd.) Water-soluble urea resin (eg, manufactured by K.K.); oxazoline-based reactive polymer K-1
Aqueous oxazoline compounds such as 020E (trade name, manufactured by Nippon Shokubai Kagaku Kogyo); and the like.

By using the above-mentioned curing agent in combination in the dispersion containing the alumina hydrate and the above binder, the water resistance of the resulting ink receiving layer can be improved.

The amount of the curing agent used is 5% of the solid content of the binder.
It is preferably about 40% by weight. As a whole dispersion, the curing agent is considered to be part of the binder.

The waterproofing agent can be arbitrarily selected from known materials such as halogenated quaternary ammonium salts and quaternary ammonium salt polymers.

The ink receiving layer is formed by a method of coating a dispersion containing alumina hydrate, a binder and the like on a base material using a coating apparatus and drying the dispersion. As a coating method, for example, a blade coating method, an air knife method,
Roll coating method, brush coating method, gravure coating method, kiss coating method, extrusion method,
A slide hopper (slide beat) method, a curtain coating method, a spray method, or the like can be used.

The coating amount of the dispersion liquid for forming the ink receiving layer is preferably 0.5 to 60 g / m ² in terms of solid content,
It is more preferably in the range of 5 to 45 g / m ² , and in this range, good ink absorbability and image resolution can be obtained. When the coating amount is expressed by the thickness of the ink receiving layer to be formed, it is 15 μm or more, preferably 20 μm or more.

As the base material, papers such as appropriately sized papers, non-sized papers, resin-coated papers, sheet-like materials such as thermoplastic films and cloth foils can be used, and are not particularly limited. In the case of a thermoplastic film, a transparent film of polyester, polystyrene, polyvinyl chloride, polymethylmethacrylate, cellulose acetate, polyethylene, polycarbonate, etc., or an opaque sheet filled with alumina hydrate, titanium white, etc., or finely foamed is used. be able to.

In order to improve the adhesion between the substrate and the ink receiving layer, a surface treatment such as corona treatment may be carried out, or an easily adhesive layer may be provided as an undercoat layer. Further, in order to prevent curling, a curl preventing layer such as a resin layer or a pigment layer may be provided on the back surface of the substrate or a predetermined portion.

The ink used in the image forming method of the present invention mainly contains a coloring material (dye or pigment), a water-soluble organic solvent and water. As dyes, direct dyes,
Water-soluble dyes typified by acid dyes, basic dyes, reactive dyes, food dyes, etc. are preferable, and ink fixability, image colorability, sharpness, light resistance, stability, and other required performances are satisfied. Any image-providing one can be used.

The water-soluble dye is generally used by dissolving it in water or a solvent consisting of water and a water-soluble organic solvent,
As these solvent components, a mixture of water and a water-soluble organic solvent is preferably used, and the content of water in the ink is in the range of 20 to 90% by weight, preferably 60 to 90% by weight. It is preferable to adjust

As the water-soluble organic solvent, for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol and the like having 1 to 10 carbon atoms can be used. Alkyl alcohols of 4; amides such as dimethylformamide and dimethylacetamide; ketones and ketone alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyethylene glycol, polypropylene glycol and the like Polyalkylene glycols; ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene Rico - le, diethylene glycol - alkylene glycolate alkylene group such as Le contains 2-6 carbon atoms - Le acids; glycerin; ethylene glycol - Rumechirue - ether, diethylene glycol - monomethyl - ether,
And lower alkyl ethers of polyvalent alcohols such as diethylene glycol ethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether; and the like.

Among these water-soluble organic solvents, polyhydric alcohols such as ethylene glycol and diethylene glycol, triethylene glycol monomethyl ether,
Lower alkyl ethers of polyhydric alcohols such as triethylene glycol monoethyl ether are preferred. Polyhydric alcohols are particularly preferable because they are highly effective as a wetting agent for preventing clogging of the nozzle due to evaporation of water in the ink and precipitation of water-soluble dyes.

A dye solubilizer may be added to the ink. The solubilizing agent dramatically improves the solubility of the dye in a solvent, and as a typical solubilizing agent,
It is a nitrogen-containing heterocyclic ketone and includes N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like.

To improve the properties of the ink, a viscosity adjusting agent, a surfactant, a surface tension adjusting agent, a pH adjusting agent, a specific resistance adjusting agent, a storage stabilizer and the like can be further added.

An ink jet recording method is preferable as a method for recording by applying ink to a recording medium. As such an ink jet recording method, a small ink droplet is ejected from an orifice by using various driving principles. The present invention can be applied to any of the conventionally known inkjet recording methods for performing recording. As a typical example, in the method described in Japanese Patent Application Laid-Open No. 54-59936, the ink subjected to the action of thermal energy undergoes a rapid volume change, and the action force due to this state change ejects the ink from the nozzle. The inkjet method is particularly preferable because it enables high-speed printing.

[0049]

The present invention will be specifically described below with reference to examples. These examples are preferable examples of the present invention.
The present invention is not limited to these. In the sentence,
Parts are based on weight.

Production Example of Alumina Hydrate Aluminum dodexide was produced by the method described in US Pat. No. 4,242,271. Next, the aluminum dodoxide was hydrolyzed by the method described in US Pat. No. 4,202,870 to produce an alumina slurry. Water was added to this alumina slurry to make the alumina hydrate solid content 7.9%. The pH of this alumina slurry was 9.5.

A 3.9% nitric acid solution was added to this slurry to adjust the pH to obtain a colloidal sol. The colloidal sol was spray dried at 75 ° C. to obtain alumina hydrates (A and B) shown in Table 1.

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

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

The BET specific surface area (SA) is Brunau.
The value was calculated using the method of er et al.

The results are shown in Table 1.

[0056]

[Table 1]

Example 1 0.83 parts by weight of formic acid and 0.28 parts by weight of nitric acid were added to a mixed solvent of ion-exchanged water / DMF (weight ratio 8/2), and 100 parts of the above alumina hydrate A was added. Add parts by weight,
A dispersion was prepared. In this case, formic acid is 180.3 μmol and nitric acid is 44.4 μmo with respect to 1 g of alumina hydrate.
1 is included.

This dispersion was used for 2 times at a rotation speed of 1000 rpm using a disperser (trade name: portable mixer A510, using DS impeller blades, manufactured by Satake Chemical Industry Co., Ltd.).
Stir for hours.

Next, an aqueous solution was prepared by dissolving polyvinyl alcohol (trade name: Gohsenol GH-23, Nippon Synthetic Chemical Industry Co., Ltd.) in ion-exchanged water so that the solid content concentration was 10%, and alumina hydrate A was prepared. Were weighed so that the solid content weight ratio (P / B) was 10/1 and added to the above dispersion.

Further, a water-soluble melamine resin (trade name: Sumirez Resin 613 Special, Sumitomo Chemical Co., Ltd.) was used as a curing agent so that the solid weight ratio of polyvinyl alcohol / curing agent was 10 / 2.5. In addition to the above dispersion liquid, the mixture was stirred at a rotation speed of 1000 rpm for 2 hours to obtain a mixed dispersion liquid of alumina hydrate / (polyvinyl alcohol + water-soluble melamine resin) at a weight ratio of 8/1. The solid content concentration (alumina hydrate + polyvinyl alcohol + water-soluble melamine resin) of this dispersion was 18% by weight.

As a base material, a white polyester film (trade name: Melinex 339, manufactured by ICI, thickness 12)
5 μm), while subjecting this film to corona discharge treatment, kiss-coat the above-mentioned mixed dispersion liquid at a coating speed of 10 m / min and dry at 150 ° C. to give a dry coating thickness of 45 μm.
An ink receiving layer of m was formed to obtain a recording medium.

Table 2 shows the physical properties and evaluation results of this recording medium.

Evaluation / Measurement Method of Various Properties of Ink Receiving Layer 1) The state of the coating film of the ink receiving layer was visually evaluated. A good smooth surface was obtained, and a good one was found to have defects such as cracks, cracks, repelling, and streaks. 2) Glossiness Glossiness meter (Product name: Gloss Checker IG-320,
Horiba Seisakusho Co., Ltd. was used to measure 7 points on the non-printed area,
The average value of these was calculated. 3) Printing characteristics Inkjet in which a drop-on-demand type inkjet head (bubble jet type head) having 128 nozzles at a nozzle interval of 14 nozzles per 1 mm is distributed to four colors of yellow, magenta, cyan, and black. Recording was carried out by mounting the following two types of ink on a printer, and the ink absorbency, image density, bleeding, beading, and bronze were evaluated.

Ink 1 Ink composition • Dye (Y, M, C, Bk) 5 parts • Ethylene glycol 10 parts • Polyethylene glycol 10 parts • Water 75 parts Dye Y: C.I. I. Direct Yellow 86 M: C.I. I. Acid Red 35 C: C.I. I. Direct Blue 199 Bk: C.I. I. Hood black 2

Ink 2 Ink composition (Y ink composition is the same as Ink 1) Dye (M, C, Bk) 1.7 parts Ethylene glycol 10.35 parts Polyethylene glycol 10.35 parts Water 77.6 Part dye Same as ink 1

A) Ink absorbency The dry state of the ink on the surface of the ink receiving layer immediately after solid printing of the above four color inks alone or in multiple colors was examined by touching the printed portion. The amount of ink for printing 40 ng of ink on the ink receiving layer at 360 × 360 dots per square inch is 100%.

Regarding ink 1, when the ink amount is 300%, the ink does not adhere to the finger ⊚, when the ink amount is 200%, the ink does not adhere to the finger ◯, when the ink amount is 100%, the ink does not adhere to the finger Was designated as Δ.

Regarding the ink 2, when the ink amount is 350%, the ink does not adhere to the finger ⊚, when the ink amount is 300%, the ink does not adhere to the finger ∘, when the ink amount is 250%, the ink does not adhere to the finger Was designated as Δ.

B) Image Density The densities of images solidly printed with magenta inks 1 and 2 were measured using a Macbeth reflection densitometer RD1255. In each of the examples, the image density of magenta was the lowest among the four colors, and thus the individual images were evaluated. The value of the ink 2 is 300%.

C) Bleeding and Beading Ink 1 and 2 were visually printed on the surface of the ink receiving layer and the bleeding on the surface of and inside the ink receiving layer after solid printing in monochrome or in multiple colors. It was observed and evaluated. Ink amount for monochrome printing is 100%, and ink amount is 3
When bleeding and beading did not occur at 00%, the result was ⊚, when bleeding and beading did not occur at 200%, the amount was ◯, and when bleeding and beading did not occur at 100% ink, the result was Δ. .

D) Judgment was made based on whether or not the cyan dye is agglomerated on the surface of the ink receiving layer after solid printing of bronze cyan ink in a single color.

Regarding Ink 1, the one in which the ink amount was not coagulated at 300% was ⊚, the one in which the ink amount was 200% was not coagulated, and the one in which the ink amount was 100% was not coagulated.

As for ink 2, those which did not aggregate at the ink amount of 350% were evaluated as ⊚, those which did not aggregate at the ink amount of 300% were evaluated as ◯, and those which did not aggregate at the ink amount of 250% were evaluated as Δ.

Examples 2 to 22 and Reference Examples 1 and 2 A recording medium was prepared and evaluated in the same manner as in Example 1 except that the conditions shown in Tables 2 and 3 were changed. The results are shown in Tables 2 and 3.

[0075]

[Table 2]

[0076]

[Table 3]

[0077]

As described above, according to the present invention, the image density is high, the bleeding is suppressed, and the ink absorbency in the multiple recording of ink can be improved, and the occurrence of beading and the formation of bronze can be reduced.

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hiroyuki Sugada 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-9-24666 (JP, A) JP-A-4 -67985 (JP, A) JP-A-8-310114 (JP, A) JP-A-10-193777 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B41M 5/00

Claims (18)

(57) [Claims] 1. A recording medium having an ink receiving layer containing a hydrated alumina and a binder provided on a substrate, wherein the ink receiving layer contains an inorganic acid and an organic acid having a carboxyl group.
Of the organic acid and the primary acid dissociation index pKa (O)
The primary dissociation index pKa (I) is pKa (O)> pKa
An inkjet recording medium having the relationship of (I) . 2. The primary dissociation index pKa (I) of the inorganic acid.
The inkjet recording medium according to claim 1, wherein the value is 3 or less. 3. The ink jet recording medium according to claim 2, wherein the inorganic acid is selected from hydrochloric acid, nitric acid and phosphoric acid. 4. The primary dissociation index pKa (O) of the organic acid.
The inkjet according to claim 1, wherein is in the range of 1 to 5.
Use a recording medium. 5. The organic acid is formic acid, acetic acid, chloroacetic acid,
The inkjet recording medium according to claim 4, which is selected from lactic acid, citric acid, oxalic acid, maleic acid, and malonic acid. 6. The ink jet recording medium according to claim 1, wherein the inorganic acid is contained in an amount of 1 μmol to 1000 μmol with respect to 1 g of alumina hydrate. 7. The ink jet recording medium according to claim 1, wherein the organic acid is contained in an amount of 1 μmol to 1000 μmol with respect to 1 g of alumina hydrate. 8. The molar ratio of the inorganic acid and the organic acid is 10: 1.
The ink jet ink according to claim 1, which is included in the range of 1:10.
Jet recording medium. 9. A method for forming an image by applying ink droplets to a recording medium, wherein the recording medium is any one of claims 1 to 1.
An image forming method using the recording medium according to any one of 0 . 10. An alumina hydrate, a binder, an inorganic acid and an organic acid having a carboxyl group, the primary dissociation index pKa (O) of the organic acid and the primary dissociation index p of the inorganic acid.
Ka (I) has a relationship of pKa (O)> pKa (I).
An ink jet recording medium forming dispersion. 11. The primary dissociation index pKa of the inorganic acid.
The dispersion according to claim 10 , wherein (I) is 3 or less. 12. The dispersion according to claim 11 , wherein the inorganic acid is selected from hydrochloric acid, nitric acid and phosphoric acid. 13. The primary dissociation index pKa of the organic acid.
The dispersion according to claim 10 , wherein (O) is in the range of 1 to 5. 14. The method of claim 13, wherein the organic acid is formic acid, acetic acid, chloroacetic acid, lactic acid, citric acid, oxalic acid, the dispersion of claim 13 which is selected from maleic acid and malonic acid. 15. The method of claim wherein the inorganic acid is contained 1μmol~1000μmol on the alumina hydrate 1 g 10
The dispersion according to. 16. A method according to claim wherein the organic acid is contained 1μmol~1000μmol on the alumina hydrate 1 g 10
The dispersion according to. 17. The molar ratio of the inorganic acid and the organic acid is 10:
The dispersion according to claim 10 , wherein the dispersion is included in the range of 1 to 1:10. 18. A method for producing an inkjet recording medium, which comprises applying the dispersion according to claim 10 on a substrate to form an ink receiving layer.