JP3315488B2 - Inkjet recording paper - 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 sheet, and more particularly to an ink jet recording sheet capable of suppressing dot bleeding and spreading and recording at a high density.

[0002]

2. Description of the Related Art In an ink jet recording system, dots are formed by ejecting small droplets of ink by various mechanisms and attaching the ink droplets onto recording paper. In addition, there are advantages such as easy full-color printing and high-speed printing. On the other hand, the ink used in the ink jet recording method is usually an aqueous ink using a direct dye or an acidic dye, and thus has a drawback that the drying property of the ink is poor.

In general, characteristics required for recording paper used for ink jet recording include items such as a high ink drying speed, a high print density, and a small spread of dots and whisker-like bleeding. In order to improve the above problems, conventionally, it is necessary to provide an ink jet recording layer containing silica having a large specific surface area, to increase the ink absorption amount, and to increase the drying speed of the ink attached to the recording paper surface. It was done. However, when the ink absorption amount is too large, there is a drawback that the print density decreases and the dots spread.

[0004] In order to solve such a disadvantage, as described in JP-B-63-22997, the amount of voids in recording paper has been controlled. Recently, this coating type ink jet recording paper has been changed from a conventional heavy coating amount of 25 g / m ² or more as a solid content to a light coating amount of 10 g / m ² or less, which is closer to plain paper. It is shifting to a man-made one.

On the other hand, with the recent progress of ink jet printers and diversification of needs, higher resolution and higher image quality have been required, and improvements from the hardware side such as reduction of ink ejection amount and reduction of ink surface tension have been required. Has also been made.
However, using such a recent inkjet printer, when recording on a heavy-coating-type inkjet recording paper, the print density is reduced, whereas when recording on a light-coating-type inkjet recording paper, Has the drawback of causing dot bleeding and spreading.

[0006]

The inventors of the present invention have conducted intensive studies to solve the above-mentioned drawbacks. As a result, the present inventors applied a predetermined amount of a pigment and an aqueous binder in a predetermined weight ratio,
The present inventors have found that by providing a layer of a stearate compound as the outermost layer of the recording layer, it is possible to suppress bleeding and spreading of dots and to perform recording at a high density, and arrived at the present invention. Accordingly, it is an object of the present invention to provide an ink jet recording sheet which has a small dot bleeding and spread, a high recording density, and excellent ink absorbability. Ink jet recording paper characterized in that the amount is 0.01 to 1.0 g / m ² .

[0007]

SUMMARY OF THE INVENTION The above objects of the present invention are as follows.
A coating layer containing a pigment and an aqueous binder on at least one surface of the base paper and having a solid content weight per side of 1 to 25 g / m ² , and a stearate compound provided on the layer;
An ink jet recording paper provided with a recording layer composed of a layer of a product , wherein the ratio of the pigment and the aqueous binder in the coating layer is in the range of 40/60 to 80/20 by weight. This was achieved by an ink jet recording paper characterized in that the applied amount of the stearic acid salt compound was 0.01 to 1.0 g / m ² in terms of solid content weight.

In the present invention, the recording layer comprises a coating layer containing a pigment and an aqueous binder as main components (hereinafter simply referred to as a coating layer) and a stearate compound provided on the coating layer . And layers. The pigment used in the present invention can be appropriately selected from known ones and used. Specific examples of such pigments include kaolin, aluminum hydroxide, calcium carbonate, zinc oxide, plastic pigment, synthetic silica, and the like, and two or more of these may be used in combination. In the present invention, it is particularly preferable to use silica having a large specific surface area and a high absorption capacity.

Examples of the aqueous binder include starches such as oxidized starch and esterified starch, cellulose derivatives such as carboxymethylcellulose and hydroxyethylcellulose, polyvinyl alcohol and its derivatives, casein, gelatin, soy protein, styrene / maleic resin. And derivatives thereof, styrene / butadiene-based latex, vinyl acetate-based emulsion, and the like, and two or more of these may be used in combination.

In the present invention, the preferred ratio of the pigment to the aqueous binder is 40 to 80% by weight of the pigment and 60 to 20% by weight of the aqueous binder.
It is preferable that the amount of the aqueous binder is in the range of 50 to 30% by weight in the range of 0 to 70% by weight. When the content of the pigment is less than 40% by weight, the absorbability of the ink into the ink recording layer becomes insufficient. Conversely, if the content of the pigment exceeds 80% by weight, the amount of the aqueous binder becomes less than 20% by weight, so that the adhesive strength of the recording layer decreases.

The coating liquid for the coating layer may contain a pigment dispersant, a water retention agent, a thickener, a defoaming agent, a preservative, a coloring pigment, a water resistance agent, a wetting agent, if necessary. Fluorescent dyes and ultraviolet absorbers can be added. The coating liquid thus prepared is applied to a base paper by a known coating method such as a roll coater method, an air knife coater method, a blade coater method, a curtain coater method, a bar coater method, a gravure coater method, and a comma coater method. .

The coating amount is usually in the range of 1 to 25 g / m ^{2 in} terms of solid content per one side of the base paper, and especially 4 to 25 g / m ^2.
g / m ² . Coating amount 1g /
m ² less when it comes to easy bleeding dots occur, 25 g
Beyond / m ^2, the printing density tends to decrease. In the present invention, on the outermost surface of the coating layer thus provided, 0.01 to 1.0 g of a layer of a stearate compound.
/ M ² , preferably in the range of 0.1 to 0.8 g / m ² .

[0013] 0.01 g of a layer of a stearate compound
If it is less than / m ² , the ink spreads unevenly in the horizontal direction and dot bleeding is likely to occur, and if it exceeds 1.0 g / m ² , the penetration of the ink into the inside of the recording layer is hindered, so that the ink absorption Worse. That is, a stearate compound
A layer of the product on the surface of the coating layer in an amount of 0.01 to 1.0 g / m ^2.
In this case, it has almost no effect on the penetration of the ink into the recording layer, and suppresses the uneven spread of the ink on the surface of the recording layer. As a result, recording paper with high print quality can be obtained.

[0014]

The stearate compound is applied to the coating layer by a method using a coating apparatus such as a roll coater or a bar coater, a method of spraying with a spray or the like, a method of coating a drum and transferring it, and the like. . The base paper used in the present invention is not particularly limited, and is appropriately selected from known papers such as neutral paper mainly made of wood pulp, which is usually used for ink jet recording paper. be able to.

[0016]

The recording layer of the ink jet recording paper of the present invention has a predetermined amount of a coating layer containing a pigment and an aqueous binder in a predetermined weight ratio, and a portion provided on the surface of the coating layer. Since it is composed of a fixed amount of a layer of a stearate compound, it is possible to suppress bleeding and spread of dots and record at a high density. Therefore, the inkjet recording paper of the present invention is suitable for recording a full-color image having high image quality and high gradation.

[0017]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.
In addition, “part” indicating the amount of addition and “%” indicating the content represent “part by weight” and “% by weight”, respectively. The tests, measurement methods, and evaluation criteria performed in Examples and Comparative Examples are as follows.

(1) Ink Absorbability An image was recorded using an ink jet printer (10-725: trade name, manufactured by Sharp Corporation), and the solid black portion immediately after printing was rubbed with a finger to determine the degree of ink tailing. It was evaluated visually. In addition, the evaluation criterion is that the mark ○ is good,
The mark "x" indicates that the product was defective.

(2) Solid Recording Density An image is recorded using the same ink jet printer as in (1), and the printing density of the solid black portion of the image is measured with a Macbeth densitometer (RD-517: trade name, manufactured by Macbeth). It measured using.

(3) Dot bleeding Black dots were recorded using the same ink jet printer as in (1), and evaluated using an optical microscope according to the following criteria. The evaluation criterion indicates that the mark “○” indicates that the spread of the dots is small and the outline is clear, and the mark “X” indicates that the spread of the dots is large and the whiskers are blurred.

(4) Adhesive strength of recording layer The adhesive strength was measured according to JIS K-5400 (pencil scratch test) and evaluated according to the following criteria. The pencil hardness is H. The evaluation criterion was that the mark ○ indicates that the coating layer did not peel off,
The mark indicates that the coating layer does not peel off.

Embodiment 1 FIG. Synthetic silica (Fine Seal X-37B: trade name manufactured by Tokuyama Soda Co., Ltd.) as a pigment 6
0 parts were dispersed in 540 parts of water. The obtained dispersion was mixed with an aqueous polyvinyl alcohol solution obtained by dissolving 40 parts of polyvinyl alcohol (PVA117: trade name of Kuraray Co., Ltd.) in 360 parts of water to obtain a coating layer liquid.

Next, the obtained coating layer liquid was applied to a basis weight of 60 g.
/ M ² base paper was coated with a roll coater so that the solid content was 20 g / m ² and dried to form a coating layer. Further, calcium stearate (Nopcoat C-104: trade name, manufactured by San Nopco Co., Ltd.) as a water-repellent substance was applied on the obtained coating layer with a bar coater so that the solid content was 0.3 g / m ^2. It was coated and dried to produce an ink jet recording paper. The above-described tests were performed on the obtained inkjet recording paper, and the results of the evaluation are shown in Table 1.

Embodiment 2 FIG. Example 1 was repeated except that the coating amount of the coating layer was changed from 20 g / m ² to 23 g / m ² and the coating amount of the water-repellent substance was changed from 0.3 g / m ² to 0.9 g / m ^2.
Inkjet recording paper was prepared in exactly the same manner as described above, and each test was performed and evaluated in the same manner. Table 1 shows the results.

Embodiment 3 FIG. As a pigment, 75 parts of synthetic silica was dispersed in 675 parts of water. The obtained dispersion was mixed with an aqueous solution of polyvinyl alcohol obtained by dissolving 25 parts of polyvinyl alcohol in 225 parts of water to obtain a coating layer liquid.

Next, the obtained coating layer liquid was applied to a basis weight of 60 g.
/ M ² base paper was coated with a roll coater so that the solid content was 4 g / m ² and dried to form a coating layer. Further, calcium stearate as a water-repellent substance was applied on the obtained coating layer using a bar coater so that the solid content was 0.1 g / m ² , and dried to prepare an ink jet recording paper. Each test was performed on the obtained ink jet recording paper, and the evaluation results are shown in Table 1.

Embodiment 4 FIG. As a pigment, 45 parts of synthetic silica was dispersed in 405 parts of water. The obtained dispersion was mixed with an aqueous solution of polyvinyl alcohol obtained by dissolving 55 parts of polyvinyl alcohol in 495 parts of water to obtain a coating layer liquid. Next, the obtained coating layer liquid was applied by a roll coater so that the solid content on a base paper having a basis weight of 60 g / m ² was 20 g / m ² , and dried to form a coating layer.

Further, on the obtained coating layer, a wax emulsion (Pulnit 101Z: trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.) having a solid content of 0.3 g / m ² was used as a water-repellent substance.
Was applied by a bar coater and dried to prepare an ink jet recording paper. Each test was performed on the obtained ink jet recording paper, and the evaluation results are shown in Table 1.

Comparative Example 1 Other than not providing a water-repellent material layer,
Inkjet recording paper was prepared in exactly the same manner as in Example 1, and each test was performed to evaluate. Table 1 shows the results.

Comparative Example 2 An ink jet recording paper was prepared in exactly the same manner as in Example 1 except that the coating amount of calcium stearate was applied with a bar coater so that the solid content became 1.2 g / m ² and dried, and each test was conducted. And evaluated. Table 1 shows the results.

Comparative Example 3 As a pigment, 90 parts of synthetic silica was dispersed in 810 parts of water. Except for obtaining a coating layer liquid by mixing the obtained dispersion and polyvinyl alcohol obtained by dissolving 10 parts of polyvinyl alcohol in 900 parts of water,
Inkjet recording paper was prepared in exactly the same manner as in Example 1, and each test was performed to evaluate. Table 1 shows the results.

Comparative Example 4 As a pigment, 30 parts of synthetic silica was dispersed in 270 parts of water. Ink jet recording was performed in exactly the same manner as in Example 1 except that the obtained dispersion was mixed with an aqueous solution of polyvinyl alcohol obtained by dissolving 70 parts of polyvinyl alcohol in 630 parts of water to obtain a coating layer liquid. Paper was prepared and each test was performed to evaluate. Table 1 shows the results.
Shown in

Comparative Example 5 Except that the coating amount of the coating layer was changed from 20 g / m ² to 0.5 g / m ² , an ink jet recording paper was produced in exactly the same manner as in Example 1, and each test was performed to evaluate. Table 1 shows the results.

Comparative Example 6 Except that the coating amount of the coating layer was changed from 20 g / m ² to 30 g / m ² , an ink jet recording paper was produced in exactly the same manner as in Example 1, and each test was performed to evaluate. Table 1 shows the results.

[Table 1] In Table 1, P / B ^* represents pigment (silica) / water-based binder (PVA).

Continuation of the front page (56) References JP-A-7-89220 (JP, A) JP-A-63-264391 (JP, A) JP-A-58-76292 (JP, A) JP-A-63-1583 (JP, A) , A) JP-A-61-237682 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/00 D21H 19/36 D21H 27/00

Claims (1)

(57) [Claims] A pigment and an aqueous binder are contained on at least one surface of a base paper, and 1 to 25 g in terms of solid weight per one side.
/ M ² , and a recording layer comprising a layer of a stearate compound provided on the coating layer, wherein the pigment and the aqueous binder in the coating layer are provided. The ratio of the agents is in the range of 40/60 to 80/20 by weight, and the amount of the stearate-based compound applied is
An ink jet recording paper having a solid content of 0.01 to 1.0 g / m ² .