JP2003170656A - Ink jet recording body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet recording body, an enough surface strength of which is obtained even under a condition that the mixing amount of a binder is reduced and in which no ununiform develops as a result of the reduced mixing amount of the binder and which is excellent in color developing properties and ink absorbency. <P>SOLUTION: In this ink jet recording body, an ink receiving layer including a synthetic amorphous silica having an oil absorption of 300 ml or more of particles and a heavy calcium carbonate having average particle diameter of 0.5 to 0.7 μm and 95% or more of particles have ones having the particle diameter of 2 μm or less is provided on a support. The mixing ratio of the synthetic amorphous silica and the heavy calcium carbonate is 50:50 to 80:20 in weight ratio. <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 inkjet recording material excellent in color development, ink absorption and surface strength, and particularly to an inkjet recording material excellent in coating suitability.

[0002]

2. Description of the Related Art Ink jet recording systems have become popular rapidly in recent years due to their ease of full-color printing and low print noise. In this method, ink droplets are ejected from a nozzle toward a recording medium at high speed, and the ink contains a large amount of solvent. Therefore, it is necessary for the recording medium to quickly absorb the ink. Also. With the recent widespread use of computers and digital cameras, images close to those of silver halide photographs have been demanded. Therefore, the inkjet recording medium is required to have high color developability, resolution and color reproducibility.

Particularly in the field of full-color recording, a printer using a so-called dye ink, in which a dye excellent in color developability is dissolved in a solvent, is predominant. In recent years, due to the increase in speed of printers and the use of multicolor inks, ink jet recording bodies are required to have higher ink absorbency.
For this reason, inkjet-specific papers having an ink-receiving layer provided on a support are marketed by various companies. The ink receiving layer is generally composed of a pigment for absorbing the ink to develop a color, a binder for binding the pigment onto the support, an ink fixing agent for fixing the ink to the ink receiving layer and various auxiliaries. Has been done. As the pigment, synthetic amorphous silica is most commonly used from the viewpoints of ink absorbability and color developability of the pigment.

By the way, in order to secure ink absorbability in the ink receiving layer, it is generally desirable to use a pigment having a high oil absorption amount, but a pigment having a high oil absorption amount is generally more uniform than a pigment having a low oil absorption amount. When compared with the surface strength of the ink receiving layer, more binder is required. When a large amount of the binder is used, the viscosity of the coating solution generally increases, making it difficult to apply the coating, and uneven coating may occur. Since a part of the binder remains adsorbed on the pigment particles even after coating, there arises a problem that the print density and ink absorbency of the inkjet recording material become insufficient. Therefore, it is preferable that the amount of the binder is as small as possible so that the surface strength required for the inkjet recording material can be secured.

On the other hand, calcium carbonate is roughly classified into two types. One is produced by chemically reacting various raw materials with a natural product (heavy calcium carbonate) produced by physically crushing limestone as it is. There are sedimentation products (light calcium carbonate), etc. Of these, heavy calcium carbonate has a low oil absorption and is generally said to be unsuitable for an ink receiving layer. In JP-A-10-204196, the average particle size is 0.3.
Disclosed is a synthetic paper excellent in fixing ability of an inkjet ink obtained by kneading ~ 2 μm of heavy calcium carbonate into a crystalline polyolefin resin and stretching it on a film. Further, in Japanese Patent Laid-Open No. 2000-260524,
An inkjet recording material for non-aqueous ink containing 30% by weight or more of heavy calcium carbonate based on all pigments in the ink receiving layer is disclosed. But these are all
Ink absorbency and color developability are poor, and it is not suitable for commonly used full-color inkjet printers of water-based ink.

[0006]

The object of the present invention is to obtain a sufficient surface strength even if the amount of the binder is reduced, and as a result of reducing the amount of the binder, there is no coating unevenness, and especially in aqueous inks. The object is to provide an inkjet recording material having excellent properties and ink absorbability.

[0007]

DISCLOSURE OF THE INVENTION The inventors of the present invention have prepared a pigment obtained by mixing a pigment in an ink receiving layer with synthetic amorphous silica having an oil absorption of 300 ml or more and heavy calcium carbonate having an average particle diameter of 2 μm or less at a specific ratio. The inventors have found that the use of the compound (1) can reduce the compounding amount of the binder while ensuring the surface strength required for the ink jet recording material, and have reached the present invention.

Accordingly, the above object of the present invention is (1) in an ink jet recording medium in which an ink receiving layer containing at least a pigment and a binder is provided on one surface of a support, wherein the ink receiving layer is A synthetic amorphous silica having an oil absorption of 200 ml or more and heavy calcium carbonate containing 95% or more of particles having an average particle size of 0.5 to 0.7 μm and 2 μm or less are contained in the ink receiving layer. The weight ratio of the synthetic amorphous silica to the ground calcium carbonate is 50:50.
To 80:20, (2) synthetic amorphous silica having an oil absorption of 200 ml or more and an average particle size of 0.
95 particles having a diameter of 5 to 0.7 μm and a particle diameter of 2 μm or less
Ink-jet recording material according to (1), wherein an ink-receiving layer is provided by applying a coating liquid in which heavy calcium carbonate containing 100% by weight or more is dispersed in the presence of a cationic dispersant,
(3) The ink jet recording material according to (1) or (2), characterized in that the binder is 20 parts by weight or less with respect to 100 parts by weight of the pigment in the ink receiving layer.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The support used in the present invention is not particularly limited,
It may be transparent or opaque. For example, plastic films such as cellophane, polyethylene, polypropylene, soft polyvinyl chloride, hard polyvinyl chloride, polyester, fine paper, photographic paper base paper, drawing paper, drawing paper,
Art paper, coated paper, cast coated paper, kraft paper,
Examples include impregnated paper and synthetic paper, which can be appropriately used according to the application. In particular, it is preferable to use a support having ink absorbability.

The synthetic amorphous silica used in the ink receiving layer used in the present invention has an oil absorption of 200 ml /
100 g is preferred, especially 300 ml / 10
It is preferably 0 g or more. Oil absorption is 200 ml /
If the amount is less than 100 g, the ink absorbency becomes insufficient, and the defect becomes remarkable especially in the color mixing part where the ink adhesion amount is large.
Further, the smaller the oil absorption amount, the less the adsorption of the binder to the silica, so that the advantage of using the mixed pigment of the present invention with the heavy calcium carbonate tends to be lost. Although any particle size of synthetic amorphous silica can be used, the preferred particle size is 5 μm or less.

The heavy calcium carbonate used in the present invention preferably has a particle size distribution having an average particle size of 0.5 to 0.7 μm and containing 95% or more of particles having a particle size of 2 μm or less. If the average particle size is larger than 0.7 μm, the surface area of the heavy calcium carbonate is small and the ink absorption of the heavy calcium carbonate itself is poor. Therefore, it is necessary to increase the proportion of the synthetic amorphous silica. It will be difficult to reduce the amount of adhesive. In addition, the defect that the image becomes whitish is likely to occur. On the other hand, when the average particle size is smaller than 0.5 μm, the binding force between the heavy calcium carbonate particles themselves tends to decrease because the particle size is too small, which makes it difficult to reduce the amount of the binder. In addition, the fluidity of the heavy calcium carbonate dispersion tends to deteriorate. If the proportion of particles having a particle diameter of 2 μm or less is 95% or less, a defect that the image becomes whitish occurs. In addition, in the present invention, the average particle size and the particle size distribution can be measured by a laser granulometer measuring device or the like.

The synthetic amorphous silica and the ground calcium carbonate used in the present invention may be separately dispersed and then mixed, or may be simultaneously dispersed, or one of the pigments may be dispersed. Then, the other pigment may be added to and dispersed in the dispersion liquid. From the viewpoint of workability and control of dispersion,
It is preferable that the synthetic amorphous silica and the ground calcium carbonate are separately dispersed and then mixed together. A dispersant may or may not be used to disperse the synthetic amorphous silica or the ground calcium carbonate, but the presence of the cationic dispersant is effective in avoiding a shock with the ink fixing agent. Is preferred.

The mixing ratio of synthetic amorphous silica and ground calcium carbonate is preferably 50:50 to 80:20, more preferably 50:50 to 70:30. The ratio of synthetic amorphous silica to ground calcium carbonate is 5
If it is less than 0:50, the ink absorbency of the ink jet recording layer is remarkably inferior, which is a practical problem.
When it is larger than 0:20, the effect of reducing the binder by mixing the heavy calcium carbonate is lost.

As the binder used in the present invention, since the ink receiving layer is required to have ink absorbency and transparency, and the surface strength of the coated ink jet recording layer is required, Polyvinyl alcohol, which is a hydrophilic binder and is excellent in transparency and binding strength, is preferably used.
However, if necessary, vinyl acetate, oxidized starch, etherified starch, casein, gelatin, soybean protein, carboxymethyl cellulose, SB latex, NB latex, acrylic latex, ethylene vinyl acetate-based latex, polyurethane, unsaturated polyester resin, etc.
It is also possible to mix and use more than one kind. The number of parts of the binder is preferably 20 parts or less, more preferably 15 parts or less with respect to 100 parts of the pigment. Even more preferably pigment 1
It is 10 parts or less with respect to 00 parts.

In the ink jet recording layer of the ink jet recording material of the present invention, a pigment dispersant, a thickener, a defoaming agent,
The effects of the invention include a foam suppressor, a release agent, a foaming agent, a coloring dye, a coloring pigment, a fluorescent dye, an ultraviolet absorber, an antioxidant, an antiseptic, a water-proofing agent, a surfactant, and a wet paper strengthening agent. It can be appropriately added within a range that does not impair it.

In order to provide the ink receiving layer on the surface of the support, various blade coaters, roll coaters, air knife coaters, bar coaters, which are common coating equipment,
Various devices such as a gate roll coater, a curtain coater, a short dwell coater, a gravure coater, a flexo gravure coater, and a size press can be used on-machine or off-machine.

In the present invention, a base paper is used as an ink receiving layer or a machine calendar before and after coating of each ink receiving layer,
It is also possible to perform surface treatment with a calendar device such as a super calendar or a soft calendar.

[0018]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. In addition, “part” and “%” shown in the examples
Indicates parts by weight and% by weight unless otherwise specified. Also, the particle size of the ground calcium carbonate is a laser granulometer measuring device Mastersizer S (manufactured by Malvern Instruments).
It was measured at.

<Example 1> (Base paper) 90% of hardwood bleached kraft pulp and 10% of softwood bleached kraft pulp were mixed and beaten to obtain a freeness of 350 m.
4 parts of cationized starch, 0.3 part of anionized polyacrylamide, and 0.5 part of alkylketene dimer emulsion were added to the pulp adjusted to 1 and a web was formed with a Fourdrinier paper machine. After 3 stages of wet press and 2 stages of dry press in the drying part to dry, 5% phosphoric esterified starch and 0.5% polyvinyl alcohol were added to a dry press to obtain a dry weight. The base paper having a basis weight of 175 g / m ² was manufactured by applying a coating amount of 3.6 g / m ² , drying and machine calendering.

(Ink Receiving Layer) Synthetic Amorphous Silica (Cyloid ED3, Grace Devison Co., Ltd., Oil Absorption 300 m
1/100 g) 80 parts, heavy calcium carbonate (Supercoat 95, manufactured by Phimatech, average particle size 0.67μ)
m, the proportion of particles having a particle size of 2 μm or less 95.2%), 20 parts,
Polyvinyl alcohol (PVA-117, made by Kuraray) 1
5 parts, cationic ink fixing agent (Polyfix 70
0, manufactured by Showa High Polymer Co., Ltd.) and mixed with 5 parts of solid content to prepare a color having a solid content of 20%, which was coated using a blade coater so that the dry coating amount was 8 g / m ² to obtain an inkjet recording material. .

<Example 2> The base paper obtained in Example 1 was
Synthetic amorphous silica (Cyloid ED3, Grace Devison Co., oil absorption 300 ml / 100 g) and heavy calcium carbonate (Super Coat 95, Phimatech Co.) in the ratio of 80:20 in the presence of a cationic dispersant. A solid obtained by mixing 100 parts of the slurry dispersed in 1. with a solid content conversion, 15 parts of polyvinyl alcohol (PVA-117, manufactured by Kuraray), and 5 parts of a cationic ink fixing agent (Polyfix 700, manufactured by Showa Polymer Co., Ltd.). 20% color was prepared, and the dry coating amount was 8 g / m ² using a blade coater.
To obtain an ink jet recording material.

<Example 3> On the base paper obtained in Example 1,
Synthetic amorphous silica (Cyloid ED3, Grace Devison Co., oil absorption 300 ml / 100 g) and heavy calcium carbonate (Supercoat 95, Phimatech Co.) in the ratio of 50:50 in the presence of a cationic dispersant. A solid obtained by mixing 100 parts of the slurry dispersed in 1. with a solid content conversion, 10 parts of polyvinyl alcohol (PVA-117, manufactured by Kuraray), and 5 parts of a cationic ink fixing agent (Polyfix 700, manufactured by Showa High Polymer Co., Ltd.). A color of 22% was prepared and the dry coating amount was 8 g / m ² using a blade coater.
To obtain an ink jet recording material.

Comparative Example 1 The base paper obtained in Example 1 was
Synthetic amorphous silica (Cyloid ED3, Grace Devison Co., oil absorption 300 ml / 100 g) and heavy calcium carbonate (Supercoat 95, Phimatech Co.) in the ratio of 20:80 in the presence of a cationic dispersant. A solid obtained by mixing 100 parts of the slurry dispersed in 1. with a solid content conversion, 10 parts of polyvinyl alcohol (PVA-117, manufactured by Kuraray), and 5 parts of a cationic ink fixing agent (Polyfix 700, manufactured by Showa High Polymer Co., Ltd.). A color of 22% was prepared and the dry coating amount was 8 g / m ² using a blade coater.
To obtain an ink jet recording material.

<Comparative Example 2> On the base paper obtained in Example 1,
Synthetic amorphous silica (AY-601, manufactured by Nippon Silica Co., oil absorption 270 ml / 100 g) and heavy calcium carbonate (Super Coat 95, manufactured by Phimatech Co., Ltd.) were mixed at 50: 5.
100 parts by weight of a slurry dispersed in the presence of a cationic dispersant in the proportion of 0 in terms of solid content, polyvinyl alcohol (PVA-117, manufactured by Kuraray) 15 parts, cationic ink fixing agent (Polyfix 700, Showa Showa). Polymer company) 5
A color having a solid content of 22% was prepared by mixing parts, and was coated using a blade coater so that the dry coating amount was 8 g / m ² to obtain an inkjet recording material.

<Comparative Example 3> On the base paper obtained in Example 1,
Synthetic amorphous silica (Cyloid ED3, manufactured by Oil absorption amount 3)
00ml / 100g) and ground calcium carbonate (FMT-
90, manufactured by Phimatec Co., Ltd., having an average particle size of 0.69 μm, and a ratio of particles having a particle size of 2 μm or less is 89.2%).
100 parts by weight of a slurry dispersed in the presence of a cationic dispersant in the proportion of 0 in terms of solid content, polyvinyl alcohol (PVA-117, manufactured by Kuraray) 15 parts, cationic ink fixing agent (Polyfix 700, Showa Showa). Polymer company) 5
A color having a solid content of 22% was prepared by mixing parts, and was coated using a blade coater so that the dry coating amount was 8 g / m ² to obtain an inkjet recording material.

Comparative Example 4 The base paper obtained in Example 1 was
Synthetic amorphous silica (Syloid ED3, Grace Devison Co., oil absorption 300 ml / 100 g) 100 parts, polyvinyl alcohol (PVA-117, Kuraray) 40
Part, cationic ink fixing agent (Polyfix 700,
(Showa High Polymer Co., Ltd.) A color having a solid content of 22% was prepared by mixing 5 parts, and a dry coating amount was 8 g using a blade coater.
/ M ² and was coated so as to obtain an ink jet recording material.

<Evaluation Method> Each recording medium obtained in Examples and Comparative Examples was evaluated by the following methods. In each item, if it is evaluated as ◯ or more, it can be practically used. Regarding the inkjet recording evaluation, a commercially available inkjet printer PM-800C is used.
(Inkjet printer manufactured by Seiko Epson) was used.

<Color development> Black, cyan, magenta,
After printing each solid image for yellow and letting it stand for one day, the printing density of each image area was measured by a reflection densitometer (MACHBET
It was measured by HRD 914) and evaluated by the total of the measured values obtained. ◯: The total of four colors is 6.5 or more. Δ: The total of four colors is 6.0 or more and less than 6.5. X: The total of four colors is less than 6.0.

<Surface Strength> An adhesive tape having a width of 18 mm was attached to the sample, and the force required for peeling it off was measured using a digital force gauge. ◯: The measured value is 600 gf or more. Δ: The measured value is 500 gf or more and less than 600 gf. X: The measured value is less than 500 gf.

<Ink Absorption> Solid images of red and green were printed side by side, and the degree of bleeding at the boundary was evaluated. ◯: The boundary is clear and no bleeding is observed. Δ: The boundary is slightly blurred but no bleeding is observed. ×: The boundary is unclear and bleeding is recognized.

<Printing unevenness> A solid green surface was printed on the front surface of A4, and the solid printed surface was visually judged. ◯: No print unevenness is observed Δ: Some print unevenness is seen ×: Print unevenness is severely impractical and the evaluation results are as shown in Table 1.

[0032]

[Table 1]

In Table 1, comparing Examples 1 to 3 with Comparative Example, first, in Comparative Example 1 having a large amount of heavy calcium carbonate, the ink absorption amount of the pigment was insufficient, so that the ink receiving layer could not sufficiently receive the ink. Inferior in print density and ink absorption. Oil absorption of 300 ml / 10 on synthetic amorphous silica
In Comparative Example 2 in which 0 g or less was used, the oil absorption of the pigment was reduced, and thus the ink absorption was slightly inferior. Also,
In Comparative Example 3 in which the heavy calcium carbonate in which the proportion of particles having a particle diameter of 2 μm or less is less than 95% is used, the image becomes whitish and thus the print density is lowered. In Comparative Example 4 using only the synthetic amorphous silica, the printing density and the ink absorption were very good, but the viscosity of the coating was high due to the large amount of binder, which made it difficult to apply it uniformly on the base paper. There is uneven printing, which is a problem in production.

[0034]

According to the present invention, the ratio of the synthetic amorphous silica having an oil absorption of 200 ml / 100 g or more and the particles having an average particle size of 0.5 to 0.7 μm and a particle size of 2 μm or less is contained in the ink receiving layer. By mixing 95% or more of heavy calcium carbonate in a specific ratio, an ink jet recording material was obtained that satisfied the balance of print density, ink absorption, and surface strength even with a low coating amount and had no print unevenness. Further, by using a cationic dispersant as a pigment dispersant and reducing the amount of a binder, it is possible to obtain an inkjet recording material having an ink receiving layer that suppresses thickening of the coating liquid and has no coating unevenness. I was able to.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tsuyoshi Yasuda             5-21-1 Oji, Kita-ku, Tokyo Nippon Paper Industries             Product Research Institute Co., Ltd. F-term (reference) 2C056 EA04 FB02 FC06                 2H086 BA15 BA31 BA33 BA45 BA47

Claims (4)

[Claims] 1. An ink jet recording medium comprising an ink receiving layer containing a pigment and a binder on at least one surface of a support, wherein the ink receiving layer is a synthetic amorphous material having an oil absorption of 200 ml or more. Silica and average particle size 0.5
95% of particles having a particle size of ~ 0.7 μm and a particle size of 2 μm or less
An inkjet recording material containing the above-described heavy calcium carbonate, wherein the weight ratio of the synthetic amorphous silica to the heavy calcium carbonate in the ink receiving layer is 50:50 to 80:20. 2. A dispersion liquid in which heavy calcium carbonate having an average particle size of 0.5 to 0.7 μm and 95% or more of particles having a particle size of 2 μm or less is dispersed in the presence of a cationic dispersant. The ink jet recording material according to claim 1, wherein an ink receiving layer is provided by applying the coating liquid. 3. An ink-receiving layer is provided by applying a coating liquid containing a dispersion liquid in which synthetic amorphous silica having an oil absorption of 200 ml or more is dispersed in the presence of a cationic dispersant. Item 2. The inkjet recording material according to item 2. 4. The ink jet recording material according to claim 1, wherein the binder is 20 parts by weight or less with respect to 100 parts by weight of the pigment in the ink receiving layer.