JP2002178628A - Ink jet recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording material capable of satisfying ink absorbability without bringing about a problem of a curl, lowering a coated film strength and transparency. SOLUTION: The ink jet recording material comprises an ink acceptive layer on a support. In this case, a surface of the acceptive layer has protrusions each having a height of 5.00 μm or more of 3,000 pieces or more per 1 mm2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording material for an ink jet printer, and to a recording material having excellent ink absorbency.

[0002]

2. Description of the Related Art In recent years, digitization has become widespread, and opportunities for outputting digital data such as image images from computers have been increasing. There are various output methods such as dot impact and laser.
Among them, the ink jet recording method has been widely used because of its advantages such as low hardware and running cost, and the possibility of color output.

[0003] The performance required of such an ink jet recording material is not only that it can be simply recorded by an ink jet printer, but also that it has excellent ink absorbency. That is, since the ink-jet recording material is often stored after being laminated after recording, it is intended to prevent sticking of the undried ink and the laminated member (hereinafter, referred to as “blocking”), in other words. It is desirable that the ink has excellent ink absorbency.

As means for solving this problem of ink absorbency, it is conceivable to increase the thickness of the ink receiving layer or to make the ink receiving layer have a porous structure by containing a large amount of pigment.

[0005]

However, when the thickness of the ink receiving layer is increased, curling becomes severe, and when the pigment is contained in a large amount, the coating strength of the ink receiving layer decreases. It is difficult to handle. In addition, in both the case where the thickness of the ink receiving layer is increased and the case where the pigment is contained in a large amount, the transparency of the inkjet recording material as a whole decreases, and the material after recording is overlapped. There is a problem that it becomes difficult to use in a field in which transparency is important, such as in use.

[0006]

The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, by forming the surface of the ink receiving layer into a specific shape, curling, reduction in coating film strength, It has been found that high ink absorbency can be obtained without causing a problem of a decrease in transparency, and this has been solved.

That is, the ink jet recording material of the present invention has an ink receiving layer having a height of 5.
It is characterized in that it has 3,000 or more projections of not less than 00 μm per 1 mm ² .

Preferably, among the protrusions having a height of 5.00 μm or more, 500 or more protrusions having a height of 6.35 μm or more are included per 1 mm ² .

More preferably, the height is 5.00 μm.
Among the above convex portions, a convex portion having a height of 6.35 μm or more is 1 m.
It is characterized by containing 500 to 2500 per m ² .

The ink jet recording material of the present invention having such a structure has an appropriate convex portion on the surface of the ink receiving layer, so that blocking is prevented and apparent ink absorbability can be improved.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The ink jet recording material of the present invention has an ink receiving layer having a height of 5.
It is characterized in that it has 3,000 or more projections of not less than 00 μm per 1 mm ² . Hereinafter, embodiments of each component will be described.

Examples of the support include plastic films such as polyester, polycarbonate, polyvinyl chloride, polyethylene, polypropylene, and polystyrene; synthetic paper, paper, and fiber cloth. When used, a transparent support such as a plastic film is preferably used. Although the thickness of the support is not particularly limited, a support having a thickness of 5 to 300 μm is preferably used from the viewpoint of transportability to an inkjet printer and the like.

The ink receiving layer is mainly composed of a binder resin, and mainly has a role of receiving an ink jet ink.

The binder resin is mainly composed of a water-soluble polymer, but may be a mixture of a water-resistant water-soluble polymer or a water-insoluble polymer as required.

As the water-soluble polymer, polyvinyl alcohol, polyvinylpyrrolidone, hydroxycellulose,
Synthetic resins such as melamine resin, acrylic acid, acrylic acid ester, and acrylamide copolymer, and natural resins such as gelatin, casein, starch, chitin, and chitosan are exemplified.

Examples of the water-resistant polymer which has been rendered water-resistant include those which have been insolubilized by reacting with the water-soluble polymer through ionic bonds, coordination bonds, covalent bonds, hydrogen bonds and the like.

Examples of the water-insoluble polymer include styrene-maleic acid copolymer, vinyl chloride-vinyl acetate copolymer, acrylic resin, cellulose resin, polyvinyl acetal and the like.

The surface of the ink receiving layer has a height of 5.00 μm.
It has 3000 or more, preferably 4000 or more, and more preferably 5000 or more of the above-mentioned convex portions per 1 mm ² . 1 mm of convex part with a height of 5.00 μm or more
^{When the} number of protrusions is 3,000 or more, the interval between the protruding portions becomes dense, the anti-blocking effect is enhanced, and the apparent ink absorbability can be improved. The number of the convex portions having a height of 5.00 μm or more is desirably not more than 10,000, preferably not more than 8,000, more preferably not more than 7000 per 1 mm ² while satisfying the above-mentioned number. When the number is 10,000 or less, it is possible to prevent a decrease in transparency.

The surface of the ink-receiving layer is provided with 500 or more, preferably 600 or more per mm ² of the above-mentioned convex portions having a height of 5.00 μm or more, the convex portions having a height of 6.35 μm or more. More preferably, it is desirable to include 700 or more. The reason why 500 or more protrusions with a height of 6.35 μm are included per mm ² among the protrusions with a height of 5.00 μm or more is that only the protrusions with a height of 5.00 to 6.35 μm satisfy ink absorption. It can be made to work, but the height is 6.
This is because by including the projections of 35 μm or more, it becomes possible to obtain more sufficient ink absorbency. The number of protrusions having a height of 6.35 μm or more is not more than 2500, and preferably not more than 2500, preferably ² per mm 2.
It is desirable that the number be 000 or less, more preferably 1500 or less. By setting the number to 2500 or less per 1 mm ^2, the high-elevation convex portions on the surface of the ink receiving layer are reduced, and the surface is no longer lumpy, and the appearance and feel can be prevented from lowering.

The height and the number of the convex portions on the surface of the ink receiving layer are measured by a stylus type three-dimensional surface roughness measuring device (SA).
(S-2010 SAU-II: Meishin Koki Co., Ltd.) to measure the number of “mountain peak counts”. Specifically, a fixed reference level is provided in the positive direction from the average line of the extracted curve of the obtained data (when the number of protrusions having a height of 5.00 μm or more is measured, the reference level is set to 5.00 μm). ), And the number of points (mountain peak counts) exceeding the reference level after falling to the negative side from the average line was defined as the number of projections having a certain height or more.

In order to impart the surface shape as described above to the surface of the ink receiving layer, a pigment is added to the ink receiving layer, a mat layer is formed between the support and the ink receiving layer, There is a method of matting the body itself.

As the pigment to be added to the ink receiving layer,
Inorganic pigments such as silica, clay, talc, diatomaceous earth, calcium carbonate, calcium sulfate, barium sulfate, aluminum silicate, titanium oxide, zinc oxide, synthetic zeolites, alumina, smectite, etc., as well as polymethyl methacrylate, polystyrene, polyurethane, benzoguanamine, Organic pigments such as resin beads made of silicone resin, acrylic resin or the like, or hollow resin beads made of these as a raw material can be used.
A mixture of more than one species can be used. Among these, porous pigments are preferable because they can themselves absorb ink and improve ink absorbency. Further, among the silicas, porous spherical silica is suitable in that it can effectively prevent bleeding of an image and is excellent in dispersibility of a pigment (porous spherical silica) when a coating is formed on the ink receiving layer.

When a pigment is added to the ink receiving layer, the amount of the pigment is preferably in the range of 1 to 50% by weight, and more preferably 15 to 35% by weight, based on the binder resin. When the content is 1% by weight or more, sufficient ink absorbency can be exhibited, and when the content is 50% by weight or less, a decrease in coating film strength and transparency can be prevented. The pigment has an average particle size of at least 8 μm, preferably 1 μm.
It is desirable that the thickness be 0 μm or more. Average particle size of 8
When the thickness is at least μm, sufficient ink absorbency can be exhibited. Further, it is preferable to use a pigment having an average particle diameter of 6 μm or less in addition to the pigment having an average particle diameter of 8 μm or more. By using a pigment having an average particle diameter of 6 μm or less, unevenness of the coating film is prevented, and a height of 5.00 that is difficult to form with only a pigment having an average particle diameter of 8 μm or more is used.
It is possible to easily form a convex portion having a thickness of up to 6.35 μm. The pigment having an average particle size of 8 μm or more and the average particle size of 6 μm
The mixing ratio of the following pigments is desirably 1: 4 to 2: 1, preferably 1: 3 to 1: 1 by weight.

The mat layer between the support and the ink receiving layer is coated with a coating solution containing the pigment and the binder resin described above.
It can be formed by coating and drying on a support. Examples of the binder resin include known thermoplastic resins and thermosetting resins in addition to those exemplified as the binder resin for the ink receiving layer.

As a method of forming the support itself into a mat,
Sand blasting, in which fine sand is blown onto the support at high speed, and chemical etching, in which the support is treated with a chemical, may be used.

The thickness of the ink receiving layer is selected in the range of 5 to 40 μm, preferably 10 to 30 μm. When the thickness is 5 μm or more, sufficient ink absorbency can be obtained, and when the thickness is 40 μm or less, curling, reduction in transparency, and increase in price can be prevented.

In the ink receiving layer, a leveling agent, an ultraviolet absorber, an antioxidant,
Additives such as chelating agents can be added.

As a method of forming the ink receiving layer as described above, the above-mentioned binder resin, pigment and optional additives are dissolved or dispersed in a suitable solvent to prepare a coating liquid, and the coating liquid is prepared. Examples include a method of applying and drying the working liquid on a support by a known method such as a roll coating method, a bar coating method, a spray coating method, and an air knife coating method, and a method of hot melt coating the above mixture.

In the ink jet recording material of the present invention, the above-mentioned ink receiving layer needs to be on the outermost surface side of the ink jet recording material, but the ink receiving layer has another ink receiving layer between the ink receiving layer and the support. The layer may be composed of two or more layers.

Further, an anchor coat layer is provided between the ink receiving layer and the support to adjust the adhesiveness of the ink receiving layer, and the opposite side of the support to the ink receiving layer is used to prevent curling. A matte layer is provided between the ink receiving layer and the support in order to provide a back coat layer on the surface or to remove writable portions of the ink receiving layer when a portion of the ink receiving layer having a recording error is removed. It doesn't hurt anything.

As described above, in the present invention, the surface of the ink receiving layer has a convex portion having a height of 5.00 μm or more of 1 mm.
^It has more than 3000 per ² pieces. As a result, the problem of ink absorbency can be solved without causing the problems of curling, reduction in coating film strength, and reduction in transparency. Further, by including 500 or more convex portions having a height of 6.35 μm or more per 1 mm ² among the convex portions having a height of 5.00 μm or more, the ink absorbency can be further improved.

[0032]

The present invention will be further described with reference to the following examples.
Note that “parts” and “%” are based on weight unless otherwise specified.

Example 1 On a 100 μm thick transparent polyester film (Lumilar T60: Toray Industries, Inc.), a coating liquid for an ink receiving layer having the following composition was dried to a thickness of 2
It was applied by a bar coating method to a thickness of 0 μm and dried to form an ink receiving layer. Next, a coating liquid for curl prevention layer composed of a modified polyester resin (Pesthresin) is formed on the surface of the polyester film opposite to the ink receiving layer.
A513E: Takamatsu Yushi Co., Ltd., 30% aqueous dispersion) dried film thickness 15μ
m was applied by a bar coating method and dried to form an anti-curl layer to obtain an ink jet recording material of the present invention.

<Coating liquid for ink receiving layer> 15 parts of polyvinyl alcohol (Gohsenol KH-17: Nippon Synthetic Chemical Industry Co., Ltd.) 3 parts of silica (average particle size 5.2 μm) (Sylysia 450: Fuji Silysia Chemical Ltd.)・ Silica (average particle size 12μm) 2 parts (Sylysia 470: Fuji Silysia Chemical Ltd.) ・ Water 200 parts

Example 2 An ink jet recording material was prepared in the same manner as in Example 1, except that the following composition was used as the coating liquid for the ink receiving layer.

<Coating liquid for ink receiving layer> 15 parts of polyvinyl alcohol (Gohsenol KH-17: Nippon Synthetic Chemical Industry Co., Ltd.) 4 parts of silica (average particle size 5.2 μm) (Sylysia 450: Fuji Silysia Chemical Ltd.)・ Silica (average particle size 12μm) 1 part (Sylysia 470: Fuji Silysia Chemical Ltd.) ・ Water 200 parts

Comparative Example 1 An ink jet recording material was prepared in the same manner as in Example 1 except that the following composition was used as the coating liquid for the ink receiving layer.

<Coating liquid for ink receiving layer> 15 parts of polyvinyl alcohol (Gohsenol KH-17: Nippon Synthetic Chemical Industry Co., Ltd.) 5 parts of silica (average particle size 3.5 μm) (Sylysia 440: Fuji Silysia Chemical Ltd.)・ 200 parts of water

Comparative Example 2 The thickness of the ink receiving layer was 50 μm.
An ink-jet recording material was produced in the same manner as in Comparative Example 1 except that m was used.

Comparative Example 3 An ink jet recording material was produced in the same manner as in Example 1, except that the following composition was used as the coating liquid for the ink receiving layer.

<Coating liquid for ink receiving layer> 15 parts of polyvinyl alcohol (Gohsenol KH-17: Nippon Synthetic Chemical Industry Co., Ltd.) 35 parts of silica (average particle size 2.5 μm) (Sylysia 430: Fuji Silysia Chemical Ltd.)・ 200 parts of water

With respect to the ink jet recording materials obtained in Examples 1 and 2 and Comparative Examples 1 to 3, the surface of the ink receiving layer was measured with a stylus type three-dimensional surface roughness measuring device (SAS-2010 SA).
U-II: Meishinkoki Co., Ltd.) was used to count the number of “mountain peak counts”. Table 1 shows the results. The measurement range is 1.024 mm (X axis) × 0.400 mm (Y
Axis), and the measurement pitch of the Y axis was 2 μm.

[0043]

[Table 1]

The following items were evaluated for the ink jet recording materials obtained in Examples 1 and 2 and Comparative Examples 1 to 3. Table 2 shows the results.

(1) Ink Absorbability An ink jet printer (B
JC-420J: Canon Inc.) was used to record test patterns. After a certain period of time, a commercially available copy sheet was pressed against the recording surface, and when the copy sheet was peeled off, an evaluation was made based on whether or not the pattern was transferred to the copy sheet.
When the pattern did not transfer after 3 minutes, "◎" indicates that the pattern did not transfer after 5 minutes. "O" indicates that the pattern did not transfer after 5 minutes. "X" indicates that the pattern transferred after 5 minutes. . (2) Anti-curl property A sample was prepared by cutting an ink jet recording material into a size of 150 mm x 150 mm, and a temperature of 20 ° C and a humidity of 3
The curl radius of curvature was measured after hanging vertically for 24 hours under an environmental condition of 0% RH. As a result, the curl radius of curvature is shifted to the plus side or the minus side with respect to the ink receiving layer by three.
Those with a length of 00 mm or more were marked with “○”, and those with a length of less than 300 mm on the plus or minus side were marked with “x”. Here, the plus side with respect to the ink receiving layer means a curl such that the ink receiving layer side is concave, and the minus side with respect to the ink receiving layer means that the ink receiving layer side is convex. Means curling. (3) Coating strength When the ink jet recording material was bent, the coating which did not have any defect was evaluated as "O", and the coating which had a defect was evaluated as "x". (4) Transparency When an unprinted inkjet recording material is superimposed on an inkjet recording material on which a test pattern has been printed,
If the lower test pattern was sufficiently recognized,
Those that could not be sufficiently recognized were marked with "x".

[0046]

[Table 2]

In the case of Example 1, the number of the convex portions having a height of 5.00 μm or more is 3000 or more per 1 mm ^{2, and the} number of the convex portions having a height of 6.35 μm or more is 500 or more per 1 mm ^2. . Therefore, the test pattern was not transferred to the paper, and the ink absorption was satisfied. In addition, it was not inferior in anti-curl property, coating film strength and transparency. In addition, since the number of protrusions with a height of 6.35 μm or more is 2500 or less per 1 mm ² ,
It was not inferior in appearance or feel.

In the case of Example 2, the number of protrusions having a height of 5.00 μm or more is 3000 or more per 1 mm ^{2, and the} number of protrusions having a height of 6.35 μm or more is 50 / mm ^2.
It does not have 0 or more. Accordingly, the ink absorbing property was satisfied, though slightly inferior to that of Example 1. In addition, it was not inferior in anti-curl property, coating film strength and transparency.

Each of Comparative Examples 1 to 3 has a height of 5.
1 mm for protrusions of 00 μm or more^TwoMore than 3000 pieces per
And a protrusion having a height of 6.35 μm or more
mm ^TwoPer 500 or more.

In Comparative Example 1, since the amount of pigment added was relatively small, the strength of the coating film and the transparency were not inferior, but the ink absorption was not satisfactory.

In Comparative Example 2, the ink-receiving layer has a large thickness, and thus has relatively excellent ink absorbability. However, on the other hand, transparency is not satisfactory.
Moreover, despite the presence of the curl prevention layer, the degree of curl was severe.

In Comparative Example 3, the ink-receiving layer had a porous structure, and thus had excellent ink absorbability.
However, since the ink receiving layer contains a large amount of pigment, the coating film strength and the transparency were not satisfactory.

[Comparative Example 4] As the ink jet recording material of Comparative Example 4, commercially available ink jet recording materials (samples A to D) were prepared.

When the ink absorptivity of the ink jet recording materials of Comparative Example 4 (samples A to D) was evaluated in the same manner as in Example 1, the pattern was transferred even after 5 minutes. The ink absorption was not satisfactory. The surface of the ink receiving layer of each of Samples A to D was measured with a stylus type three-dimensional surface roughness measuring device (SAS-2010SA).
U-II: Meishinki Co., Ltd.) was used to measure the number of “mountain peak counts”.
Without having 3000 or more per 1 mm ² or more convex portions and the height 6.35μm or more posts were those who does not have 1 mm ² per 500 or more. Table 3 shows the results. The measurement range is 1.024 mm (X axis) x
0.400 mm (Y axis), Y axis measurement pitch is 2
μm.

[0055]

[Table 3]

[0056]

As described above, according to the present invention, the surface of the ink receiving layer has a protrusion of 5.00 μm or more in height of 1 m.
It has 3000 or more per m ² . As a result, the problem of ink absorbency can be solved without causing the problems of curling, reduction in coating film strength, and reduction in transparency. Further, by including 500 or more convex portions having a height of 6.35 μm or more per 1 mm ² among the convex portions having a height of 5.00 μm or more, the ink absorbency can be further improved.

Claims (3)

[Claims] 1. An ink jet recording material having an ink receiving layer on a support, wherein the surface of the ink receiving layer is
Protrusions with a height of 5.00 μm or more are 3,000 per mm ²
An ink jet recording material comprising at least one ink jet recording material. 2. A projection having a height of 5.00 μm or more,
^2. The ink jet recording material according to claim 1, wherein the ink jet recording material comprises 500 or more convex portions having a height of 6.35 μm or more per 1 mm ² . 3. A projection having a height of 5.00 μm or more.
The protrusion having a height of 6.35 μm or more is 500 to 1 mm ² .
2. The ink-jet recording material according to claim 1, wherein the ink-jet recording material contains 2500 inks.