JPH06255235A - Recording medium - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain a printed matter with high color density and no unevenness. A recording medium having a porous surface layer containing silica and boehmite on a substrate made of paper, wherein the coating amount of boehmite on the surface layer is 0.5 to 3 g / m.
^2. A recording medium in which the silica content in the surface layer is 0.1 to 0.4 parts by weight relative to 1 part by weight of boehmite.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium, especially a recording medium for an ink jet printer.

[0002]

2. Description of the Related Art Ink jet recording systems are rapidly becoming widespread in the fields of computers, hard copies such as video and color copiers because they are easy to achieve full color and high speed. Requirements required in these fields include high resolution, good color reproducibility (sufficient color gradation is ensured), high-speed printing capability, and good storage stability. To be

In order to achieve these, improvements have been made from both sides of the printer and the recording medium (recording material). The requirements that an inkjet recording medium must meet are:
The color density of each ink dot is high, the ink is absorbed quickly, the ink dots are spread appropriately,
For example, it may have sufficient strength for practical use.

Conventionally, as such a recording medium, there is known one in which porous silica fine particles are coated on the surface of paper together with a binder such as polyvinyl alcohol, and the porous silica fine particles absorb ink to form a color. A recording medium obtained by coating aluminum oxide or its hydrate with silica on paper is also known (see Japanese Patent Laid-Open No. 1-97678).

[0005]

In a recording medium provided with a coating layer of porous silica on the surface of paper, the color development at the time of recording is not always sufficient, and the color density may be insufficient. . In addition, in a recording medium having a coating layer of aluminum oxide or a hydrate thereof, the color density is sufficient, but when recording with an inkjet printer, for example, the "connecting streak" of the scanning of the head that ejects the ink. Sometimes occurred. An object of the present invention is to obtain a recording medium which has a high color density and an extremely small unevenness in color development.

[0006]

The present invention is a recording medium having a porous surface layer containing silica and boehmite on a substrate made of paper, wherein the coating amount of boehmite on the surface layer is 0. 0.5 to 3 g / m ² , and the content of silica is 0.1 to 1 part by weight of boehmite in the surface layer.
The recording medium is 0.4 parts by weight.

The boehmite contained in the surface layer is AlO.
It is an alumina hydrate represented by the composition formula of OH. It is preferable to use the gel-like boehmite obtained by drying the boehmite sol, because it has high dye adsorbability and good color reproducibility after recording. Particularly, it is preferable to use a boehmite sol having a primary particle diameter of crystals of 50 to 100 Å. The gel obtained by drying this boehmite sol has an average pore radius of 50 to 80Å
And the pore volume with a pore radius of 100 Å or less is 0.3-
It is preferably about 1.0 cc / g.

Such a boehmite sol is preferably synthesized by a hydrolysis method of aluminum alkoxide. According to this method, it is easy to control the particle shape of the boehmite sol.

As the silica contained in the surface layer, it is preferable to use porous silica gel. The average diameter of aggregated particles is 1 to 50 μm, and the average pore diameter is 80 to 500.
Å It is appropriate to adopt a pore volume of about 0.8 to 2.5 cc / g.

In the surface layer, it is necessary that the coating amount of boehmite is 0.5 to 3 g / m ² . When the coating amount is less than 0.5 g / m ² , the dye cannot be sufficiently fixed on the surface layer, and only a recorded matter having an insufficient color density can be obtained, which is not suitable. When the coating amount is more than 3 g / m ² , color unevenness is likely to occur particularly in a portion having a large amount of ink, such as when printing with an ink jet printer, a "stitch" occurs due to head scanning. Appropriate.

The ratio of silica to boehmite in the surface layer is 0.2 to 0.
It is preferably contained in an amount of 5 parts by weight. If the blending amount of silica is less than 0.2 parts by weight, the ink absorbency will be reduced, which is unsuitable. When the compounding amount of silica exceeds 0.5 part by weight, the color density at the time of recording is lowered, which is not suitable.

The paper used as the base material is not particularly limited, and various kinds of paper can be used. When used as a recording medium for an inkjet printer, it is preferable to use paper having good absorbency as the substrate. For example, a paper containing porous particles such as silica inside the paper, or a paper having a porous layer such as silica between the surface layer and the substrate can be preferably used.

The means for providing a mixed layer of silica and boehmite on the surface of the substrate is not particularly limited, but silica and boehmite are preferably mixed with a binder in a solvent such as water to prepare a coating solution. It is preferable to dry the composition after coating it on the substrate. For coating, for example, a roll coater, an air knife coater, a blade coater, a rod coater, a bar coater, or a comma coater is preferably used.

Although polyvinyl alcohol is mainly used as the binder, various modified polyvinyl alcohols such as cation-modified, anion-modified, silanol-modified, etc., starch and its modified products, SBR latex, N are also used.
Organic substances such as BR latex, carboxymethyl cellulose, hydroxymethyl cellulose, polyvinylpyrrolidone, and styrene-maleic acid copolymer can be used alone or in combination.

The amount of binder used is preferably about 5 to 50% by weight based on the total amount of boehmite and silica. If the amount of the binder used is less than 5% by weight, the strength of the surface layer may be insufficient.
If the amount exceeds 0% by weight, the surface layer may have insufficient absorbency or adsorptivity, which is not preferable.

When a porous intermediate layer made of silica or the like is provided, the same method as above can be adopted.

The means for recording on the recording medium of the present invention is not particularly limited, but an inkjet printer can be most preferably used. The ink to be used is preferably one containing, for example, a direct dye, an acid dye, a food coloring material as a coloring material.

[0018]

In the recording medium of the present invention, since the coating amount of boehmite is limited, the adsorption amount of the dye on the surface layer has an upper limit. Therefore, when recording with a large amount of ink, such as solid coating, the dye is adsorbed up to the upper limit of the dye adsorption amount on the surface layer, and the excess dye diffuses to the lower layer in the area where the ink is applied over the upper limit. To do. As a result, it is thought that the "stitch" when printing while scanning the head with an inkjet printer will be extremely unremarkable.

[0019]

【Example】

Example 1 Water was added to 1 part by weight of amorphous silica particles (average aggregation diameter 4 μm, average pore radius 240 Å, pore volume 1.2 cc / g) and polyvinyl alcohol 0.13 parts by weight to obtain a solid concentration of 15% by weight. To obtain a coating liquid. This coating liquid, basis weight 1
The quality paper of 00g / m ^2, the coating amount after drying of 8 g / m ²
To obtain a base material.

1 part by weight (solid content) of boehmite sol (average pore radius of gel obtained by drying sol is 65Å, pore volume of pore radius 100 Å or less is 0.8 cc / g), the above-mentioned amorphous silica Water was added to 0.2 parts by weight of the particles and 0.1 part by weight of polyvinyl alcohol to obtain a coating liquid having a solid content of 10% by weight. This coating liquid was further applied onto the silica layer of the above substrate. The coating amount of boehmite was 2 g / m ² .

On the recording medium thus obtained, an ink jet printer (Canon; CJ10) was used.
Solid black solid printing was performed. The color density is 1.42, and with the naked eye, it is a "connecting line" due to the scanning of the head.
Was not recognized.

[0022]

EFFECT OF THE INVENTION The recording medium of the present invention has high ink absorbability and can fix the dye in the ink on the surface layer, so that recording with high color density is possible. Moreover, it is a recording medium with very little unevenness in color development. In particular, when used as a recording sheet for an inkjet printer, high quality recording with less color unevenness is possible.

Claims (5)

[Claims] 1. A recording medium having a porous surface layer containing silica and boehmite on a paper substrate.
The coating amount of boehmite on the surface layer is 0.5 to 3 g /
m ² , a recording medium having a silica content of 0.1 to 0.4 parts by weight with respect to 1 part by weight of boehmite in the surface layer. 2. Boehmite is a gel obtained by drying a sol having an average pore radius of 50 to 80Å and a pore radius of 100Å.
The recording medium according to claim 1, which is boehmite obtained from boehmite sol having a pore volume of 0.3 to 1.0 cc / g. 3. Silica having an agglomerated particle average diameter of 1 to 50.
μm, average pore diameter is 80 to 500 Å, pore volume is 0.
The recording medium according to claim 1 or 2, which has a weight of 8 to 2.5 g / cc. 4. A porous silica layer is provided between the porous layer composed of silica and pseudo-boehmite and the substrate.
~ 3 any one of the recording medium. 5. The recording medium according to claim 4, wherein the porous silica layer comprises silica having an average particle diameter of 1 to 50 μm, an average pore diameter of 80 to 500Å, and a pore volume of 0.8 to 2.5 cc / g. .