JPH09123593A - Ink jet recording medium for pigment ink and recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a recording medium having excellent pigment ink absorbing properties, uniform fixing of the pigment in the ink and excellent coloring developing properties by providing a porous layer of alumina hydrate having a specific thickness and a water soluble resin layer on a base material. SOLUTION: In this recording medium suitable for an ink jet recording system using a pigment ink, a porous layer of alumina hydrate having a thickness of 1 to 200μm and a water soluble resin layer having a thickness of 0.01 to 50μm are provided on a base material. The porous layer has pores each having a pore radius of 1 to 30nm, and a pore volume of 0.3 to 2.0cc/g. The water soluble resin layer is formed of a water soluble polymer substance having a viscosity at 25 deg.C of the 1wt.% water solution of 0.01 to 10,00OcP. The resin layer contains silica or alumina particles of 5 to 50wt.% to the water soluble resin. Further, the quantity of the pigment contained in the pigment ink is 0.5 to 20wt.% to the entire ink.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium and a recording method suitable for an inkjet recording system using a pigment ink.

[0002]

2. Description of the Related Art In recent years, with the widespread use of electronic still cameras or computers, hard copy technology for recording those images on paper has been rapidly developed. The ultimate goal of these hard copies is silver halide photography, and in particular, how to bring color reproducibility, color density, resolution, gloss, weather resistance, etc. closer to those of silver halide photography is an issue for development. There are various types of hard copy recording methods, such as a sublimation type thermal transfer method, an inkjet method, an electrostatic transfer method, as well as a method of directly photographing a display displaying an image by a silver halide photograph.

Ink jet printers have become rapidly popular in recent years because they are easy to produce in full color and have low printing noise. In this method, ink droplets are ejected from a nozzle toward a recording material at a high speed, and a large amount of solvent is contained in the ink. For this reason, a recording medium for an inkjet printer is required to quickly absorb the ink and have excellent color developability.
In the ink jet recording method, an ink of a type in which a dye is dissolved in a solvent has been used so far, but an ink of a type in which a pigment is dispersed in a solvent such as water (pigment ink) is also known. The ink jet recorded matter using the pigment ink is characterized in that it has little discoloration and discoloration and is particularly excellent in durability.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides an ink jet recorded matter which has a good pigment ink absorption property, uniformly fixes the pigment in the ink to exhibit excellent color developability, and has a high color density. It is an object of the present invention to obtain a recording medium and a recording method that can be used.

[0005]

According to the present invention, a porous layer of alumina hydrate having a thickness of 1 to 200 μm is formed on a substrate, and a water-soluble resin layer having a thickness of 0.01 to 50 μm is formed thereon. And an inkjet recording medium for pigment ink.

[0006]

The base material used in the present invention is not particularly limited and various materials can be used. For example,
Plastics, specifically, polyester-based resins such as polyethylene terephthalate, polycarbonate-based resins, fluorine-based resins such as PTFE, and various types of paper, cloth, glass, metal and the like can be used. These substrates may be subjected to corona discharge treatment or various undercoats for the purpose of improving the adhesive strength of the porous layer of hydrated alumina. Although the form of the substrate is not limited, a sheet or film having a thickness of 0.01 to 1 mm is usually used.

When a transparent plastic film is used as a base material, a transparent recorded material that can be used as an OHP (overhead projector) sheet or the like can be obtained. When an opaque plastic film containing a white pigment, paper, or the like is used as the base material, a recorded matter comparable to a silver salt photograph can be obtained.

In the present invention, the porous layer of alumina hydrate functions as an absorption layer of water which is a medium component in the pigment ink. As the alumina hydrate, pseudo-boehmite is preferable because it has a good absorption function. Here, the pseudo-boehmite is an aggregate of alumina hydrate represented by the composition formula of Al ₂ O ₃ .nH ₂ O (n = 1 to 1.5).

The porous layer of hydrated alumina preferably contains a binder. As the binder, starch or a modified product thereof, polyvinyl alcohol or a modified product thereof, SBR latex, NBR latex, carboxymethyl cellulose, hydroxymethyl cellulose,
Organic substances such as polyvinylpyrrolidone can be used.

The amount of binder used is 5 hydrates of alumina hydrate.
It is preferably set to ˜50% by weight. If the amount of the binder used is less than 5% by weight, the strength of the porous layer of alumina hydrate may be insufficient, and if it is more than 50% by weight, the ink absorption may be insufficient. Because there is
Each is not preferred.

The porous layer of hydrated alumina has pores having a pore radius of 1 to 30 nm and a pore volume of 0.3 to
When it is 2.0 cc / g, it is preferable because it has sufficient absorption and the porous layer of alumina hydrate is also transparent. At this time, if the substrate is transparent, a recording medium having high transparency can be obtained. Even when the base material is opaque, it is possible to obtain a recording medium capable of obtaining an image with high quality and high color density without impairing the texture of the base material. It is more preferable that the porous layer of alumina hydrate has pores having a pore radius of 3 to 10 nm and a pore volume of 0.3 to 1.0 cc / g. The pore radius is measured by the nitrogen desorption method.

The water-soluble resin layer provided on the porous layer of alumina hydrate must be made of a material that absorbs the solvent in the ink and swells. Therefore, it is considered that the ink fixability is improved by swelling once during recording and then drying. The outermost surface of the recording medium is
Since it is a water-soluble resin layer, the drying speed of the ink is controlled within an appropriate range, and the ink surface after drying becomes smooth, so that the image quality is considered to be improved.

In the present invention, a water-soluble polymer substance is preferably used in the water-soluble resin layer. As the water-soluble polymer substance, it is preferable that the water-soluble polymer substance has physical properties such that it does not cause aggregation or gelation and forms a uniform film.

Examples of the water-soluble polymeric substance include starch, oxidized starch, or modified starch which has been grafted, etherified or esterified, methyl cellulose,
Carboxymethyl cellulose, cellulose derivatives such as hydroxyethyl cellulose, or modified cellulose such as grafting, agarose, gelatin, proteins such as casein or soybean protein, completely or partially saponified polyvinyl alcohol, or carboxylated or olefinated modified polyvinyl alcohol, Polymers such as polyvinylpyrrolidone, polyvinyl acetal, sodium polyalginate, hydrophilic urethane resin, polyacrylic acid, polyacrylamide, polyvinyl methyl ether, polyethyleneimine, or acrylic acid-vinyl alcohol copolymer, or a mixture thereof can be used. .

As the water-soluble polymer substance used in the present invention, the viscosity of a 1% by weight aqueous solution is 0.01 to 10 at 25 ° C.
It is preferably 000 cP. If it exceeds 10,000 cP, it is difficult to form a uniform film, which is not preferable. A more preferable range is 0.1 to 1000 cP.

The water-soluble resin preferably has a solubility parameter (SP value) close to that of water. The SP value of the water-soluble resin used in the present invention is 8 to 23 ca at 25 ° C.
It is preferably 1 / cm ³ .

The above-mentioned water-soluble resin layer may be a non-porous film which is formed into a uniform film, or a porous film. The water-soluble resin is applied as an aqueous solution in the case of a non-porous film, but can be applied in the form of an emulsion in the case of a porous film, and the ink is also quick-drying well. When the water-soluble resin layer is a porous layer, it is suitable that the porous layer has pores having a pore radius of 1 to 30 nm and a pore volume of 0.3 to 2.0 cc / g. .

When the water-soluble resin layer is a porous layer,
Particles of silica or alumina may be contained in order to improve quick-drying property of the ink. Silica or alumina is
They are mixed in the form of silica sol and alumina sol, respectively, when the water-soluble resin layer is formed. In this case, the amount of silica or alumina in the water-soluble resin layer is preferably 5 to 50% by weight with respect to the water-soluble resin. A more preferable range is 10 to 30% by weight.

Further, in order to impart automatic transportability to the sheet-shaped recording medium, large particle size particles having an average particle size larger than the thickness may be mixed in the water-soluble resin layer. In this case, these particles partly protrude from the water-soluble resin layer and give unevenness to the surface.

As the large-diameter particles, any shape can be used, and irregular-shaped particles can be used, but spherical particles are particularly preferable because the slidability is improved. Further, those having an average particle diameter of 0.02 to 100 μm are preferable. If it is less than 0.02 μm, the height difference of the surface irregularities is insufficient and the slipperiness cannot be exhibited, which is not preferable. 100μ
If it exceeds m, the print quality may be adversely affected, which is not preferable. More preferable range is 0.05 to 3
0 μm.

The material of the large particle size is not particularly limited, and for example, silica or various resins can be used. Examples of the resin include polystyrene and polymethylmethacrylate (PM
MA) can be used.

The content of the large-sized particles is preferably 0.001 to 5% by weight based on the water-soluble resin. When the content of the large-sized particles is less than 0.001% by weight with respect to the water-soluble resin, sufficient slipperiness cannot be obtained, which is not preferable. If the content of the large-sized particles is more than 5% by weight based on the water-soluble resin, the image quality of the recorded matter may be deteriorated, which is not preferable. A more preferable range is 0.01 to 2% by weight.

As a method for forming a porous layer of alumina hydrate on a substrate, a binder and a solvent (preferably water) are added to the alumina hydrate to form a sol coating solution, which is used as a substrate. It is preferable that the method is that the composition is applied to and then dried. When alumina sol is used as a raw material of alumina hydrate, a porous layer of alumina hydrate having good transparency can be formed, which is preferable. As a coating method, for example, a die coater, a roll coater, an air knife coater, a blade coater, a rod coater, a bar coater or a comma coater is preferably used. As a solvent for the coating liquid, either an aqueous system or a non-aqueous system can be adopted.

The thickness of the porous layer of alumina hydrate is appropriately selected according to the specifications of the printer, and is 1 to 200 μm.
Is adopted. If the thickness of the alumina hydrate layer is less than 1 μm, the ink may not be sufficiently absorbed.
If it is more than μm, the transparency of the porous layer of alumina hydrate may be impaired or the strength may be reduced. The thickness of the porous layer of alumina hydrate is particularly preferably 5 to 100 μm.

As a method for forming the water-soluble resin layer on the porous layer of alumina hydrate, a water-soluble polymer substance and, if necessary, silica sol or alumina sol are dissolved in water or dispersed in a latex form. A preferred method is to apply this on the porous layer of alumina hydrate and then dry it.
As a coating method, a die coater, a roll coater, an air knife coater, a blade coater, a rod coater, a bar coater, a comma coater or the like can be adopted as in the case of forming the porous layer of alumina hydrate.

The thickness of the water-soluble resin layer is properly selected according to the specifications of the printer and the like, and is preferably smaller than that of the porous layer of alumina hydrate, but 0.01 to 50 μm is adopted. If the thickness of the water-soluble resin layer is less than 0.01 μm, the ink fixability may not be sufficiently improved. If it exceeds 50 μm, the ink absorbability may deteriorate. The thickness of the water-soluble resin layer is 0.02-10μ
m is particularly preferred.

When ink-jet recording is performed on the recording medium of the present invention using a pigment ink, the pigment ink used is not particularly limited, and a pigment dispersed in water is used. The pigment in the pigment ink is contained in an amount of 0.5 to 20% by weight, preferably 2 to 12% by weight, based on the whole ink. The content of water in the ink is usually 10 to 93.
%, Preferably 25-87% by weight. A pH adjuster, a preservative, and the like are added to the pigment ink as needed.

The pigment of the pigment ink is carbon black produced by a furnace method or a channel method as the carbon black used for the black ink, and has a primary particle size of 15 to 4
0 nm, specific surface area by BET method is 50 to 300 m ² /
g, the volatile content is 0.5 to 12%, and the pH value is 2 to 9 is preferable.

The pigments used as the black ink, the yellow ink, the magenta ink, and the cyan ink include those listed in Table 1.

[0030]

[Table 1]

Although the above-mentioned four types of ink are used, pigments may be used alone or in combination for expressing colors.

[0032]

【Example】

[Example 1] 100 g of an alumina sol having a solid content of 18% by weight, which was synthesized by the hydrolysis / peptization method of aluminum alkoxide,
A coating solution was prepared by mixing 32 g of a 6.2 wt% aqueous solution of polyvinyl alcohol. This coating liquid was applied onto a polyethylene terephthalate film (thickness 100 μm, white) using a bar coater so that the thickness after drying was 2.6 μm, and dried to form a pseudo-boehmite layer.

Further, polyvinylpyrrolidone (manufactured by Gokyo Sangyo Co., Ltd., PVP K15, molecular weight 10000, viscosity (refers to the viscosity of a 1% by weight aqueous solution at 25 ° C., the same applies hereinafter) 3
cP) using a 10% by weight aqueous solution, and coating on the above pseudo-boehmite layer (pore volume of pores having a pore radius of 1 to 30 nm is 0.8 cc / g) at 80 ° C.
A heat treatment was carried out at a temperature of ℃ to obtain a sheet-shaped recording medium having a polyvinylpyrrolidone layer having a thickness of 0.2 μm on the surface.

"Example 2" On the pseudo-boehmite layer of Example 1, water-soluble starch (viscosity: 5 cP) and silica sol (Catalyst Chemical Co., Ltd., trade name SI-45P) were added at a solid content weight ratio of 5
A sheet-shaped recording medium was obtained in the same manner as in Example 1 except that the coating liquid adjusted to have a ratio of 1 was applied and dried so that the thickness after heat treatment was 0.2 μm.

[Example 3] Polyvinylpyrrolidone (PVP K3 manufactured by Gokyo Sangyo Co., Ltd.) was formed on the pseudo-boehmite layer of Example 1.
0, a molecular weight of 40,000, a viscosity of 3 cP) in a coating liquid having an average particle diameter of 10 μm polystyrene (manufactured by Sekisui Fine Chemical Co., Ltd., trade name Micropearl SP-
200) was applied to a resin solid content in an amount of 0.5% by weight to form a sheet-like shape except that coating was performed so that the thickness after heat treatment was 0.5 μm, and drying was performed. A recording medium was obtained.

"Example 4" Polyvinylpyrrolidone (PVP K9 manufactured by Gokyo Sangyo Co., Ltd.) was formed on the pseudo-boehmite layer of Example 1.
0, a molecular weight of 1200000, a viscosity of 5 cP) and an alumina sol synthesized by a hydrolysis / peptization method of an aluminum alkoxide were adjusted to a solid content weight ratio of 4: 1 and a thickness after heat treatment was set to 0. A sheet-shaped recording medium was obtained in the same manner as in Example 1 except that coating and drying were performed so as to have a thickness of 5 μm.

[Example 5] On the pseudo-boehmite layer of Example 1, a copolymer of acrylic acid and vinyl alcohol (Sumitomo Chemical Co., Ltd., SP-510, viscosity 1500 cP) was used, and the thickness after heat treatment was A sheet-shaped recording medium was obtained in the same manner as in Example 1 except that coating and drying were performed so as to have a thickness of 0.2 μm.

"Example 6" On the pseudo-boehmite layer of Example 1, an average particle size was obtained by applying a coating solution of a copolymer of acrylic acid and vinyl alcohol (SP-520 manufactured by Sumitomo Chemical Co., Ltd., viscosity 2500 cP). 420 μm spherical particles PMMA particles (Sekisui Fine Chemical Co., Ltd., trade name MBX2
0) was applied to a resin solid content in an amount of 0.5% by weight, and applied in a sheet form in the same manner as in Example 1 except that coating was performed so that the thickness after heat treatment was 0.2 μm, and drying was performed. A recording medium was obtained.

Example 7 (Comparative Example) A sheet-like recording medium was obtained in the same manner as in Example 1 except that the polyvinylpyrrolidone layer was not provided.

[Print Evaluation] Print evaluation was performed on the sheet-shaped recording media of Examples 1 to 7 using black ink (51629A) of an ink jet printer (DeskWriter 660C, manufactured by Hewlett-Packard Co.).

Ink fixability: After black ink was full-solid printed in a single color, it was dried at room temperature for 5 minutes and rubbed with a finger.

Beading: Black ink was used for full solid printing with a single color and then visually evaluated. When beading did not occur, it was evaluated as ○, and when it was observed, it was evaluated as ×.

Sheet Conveyance: Three A4 size sheet recording media were stacked and placed in a paper feed cassette of an ink jet printer for continuous printing. It is rated as ⊚ if all sheets can be continuously fed automatically one by one with certainty, and as ○ if feeding is somewhat bad but continuous feeding is possible, and as × when feeding sheets to the printer while they are overlapped and the sheet feeding is bad.

[0044]

[Table 2]

In the sheet recording media of Examples 1 to 6, the ink fixability was good, clear images were obtained, and the print quality was good. In Example 7, the fixability of the pigment ink was poor and the pigment peeled off when rubbed with a finger.

[0046]

The recording medium of the present invention has high absorptivity and fixability for pigment ink, and excellent color forming property and high color density. In particular, it is suitable as a recording medium for an inkjet printer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kyoko Muta, et al. 1150 Hazawa-machi, Kanagawa-ku, Yokohama, Kanagawa Prefecture Asahi Glass Co., Ltd. Central Research Laboratory

Claims (7)

[Claims] 1. A porous layer of hydrated alumina having a thickness of 1 to 200 μm on a substrate, and a layer of 0.01 to 50 μm on the porous layer.
And a water-soluble resin layer of 1. 2. The porous layer of hydrated alumina has pores having a pore radius of 1 to 30 nm as a pore volume of 0.3 to
The recording medium according to claim 1, having 2.0 cc / g. 3. The water-soluble resin layer is a 1% by weight aqueous solution at 25 ° C.
The recording medium according to claim 1 or 2, comprising a water-soluble polymer substance having a viscosity of 0.01 to 10,000 cP. 4. The water-soluble resin layer comprises 5 to 5 parts of the water-soluble resin.
A recording medium according to claim 1, 2 or 3 containing 50% by weight of particles of silica or alumina. 5. The water-soluble resin layer has an average particle size of 0.02 to 1
0.001 to 5% by weight of large-sized particles having a size of 00 μm and larger than the thickness of the water-soluble resin layer, based on the water-soluble resin
The recording medium according to claim 1, 2, 3, or 4 containing the same. 6. An ink jet recording method, wherein a pigment ink dispersed in water is ink jetted onto the water-soluble resin layer of the recording medium according to claim 1, 2, 3, 4 or 5. 7. The ink jet recording method according to claim 6, wherein the amount of the pigment contained in the pigment ink is 0.5 to 20% by weight based on the whole ink.