JPH0999631A - Ink jet receiving material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet receiving paper having excellent ink absorbability corresponding to an ink jet system of high speed printing and high emitting quantity and excellent in color forming properties and resolving power and having a uniform printing surface on its coating layer so as not to generate prindint irregularity. SOLUTION: In an ink jet receiving material wherein a coating layer is provided on base paper, as components of the coating layer, 0.05-0.5wt.% of pigment with an average particle size of 3μm or less, a water-soluble binder and a nonionic surfactant with an HLB value of 7-9 are compounded with respect to the pigment. A polymer wherein a nonionic surfactant contains an ethylene oxide unit (C2 H4 O) is pref. applied to base paper of which the Stockigt sizing degree is 10sec or less based on JIS-P8122 in a dry coating amt. of 3-12g/m<2> .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based ink jet recording material, and more specifically, it has an excellent ink absorbing ability corresponding to an ink jet system of high speed printing and a high discharge amount, and also has a color developability and a resolution. The present invention relates to a high-quality ink jet recording material having excellent printing property and having a uniform printing surface without uneven printing.

[0002]

2. Description of the Related Art Ink-jet recording is a method for obtaining an image by generating and flying small droplets of a recording liquid and adhering them to a recording material, which is low in noise and can easily achieve high quality and high resolution. Since it is possible to obtain the image of, it is rapidly spreading in recent years. Along with this, in order to obtain higher quality images, hardware improvements in the inkjet system itself, that is, faster printing, higher density, higher ejection volume, etc., have been achieved. High-level characteristics are now required.

In order to obtain high-quality images in response to high-speed printing, high-density printing, and high ejection amount, it is necessary to have high ink-absorbing ability, good ink coloring, and good ink dot density. The coating layer is high so that the ink dots are close to a perfect circle and the edges of the ink dots are smooth and the image resolution is good, and there is no uneven density or ink-free areas in the printed image. Must be uniformly formed. That is, if the fibers of the base paper are exposed on the printed surface of the coating layer, or if the surface of the coating layer is uneven, the ink will be repelled at that portion and uneven printing will occur. In addition, when the coating layer is overlaid with ink, the ink is promptly absorbed, the dots always have a constant density, and it is required that uneven printing does not occur.

In response to the above needs, for example, Japanese Patent Publication No. 2-57026 discloses an ink jet recording material in which a coating layer contains a nonionic surfactant in an amount of 1 to 10%. Further, JP-A-3-218885 discloses an ink jet recording material in which a pigment having low ink absorbability is thinly coated on a base paper of low size.

[0005]

[Problems to be solved by the invention]
In the ink jet recording material described in Japanese Patent No. 7026, the dots are sharp and the resolution is good, but the image density, especially the second color of the mixed color, sinks and the tint deteriorates. In addition, since a small amount of base paper of high size is applied, there is a problem that it cannot be applied to a system with a high discharge amount.

On the other hand, the ink jet recording material described in Japanese Patent Laid-Open No. 3-218885 uses a base paper having a low size, so that it can be applied to a system having a high ejection amount, but a pigment having a low ink absorbing ability is used. Therefore, the image density and resolution are not excellent, and the coating amount is as small as 0.5 to 20 g / m ² , so that the fibers on the base paper cannot be completely covered with the coating layer, and the fibers are exposed. The uniformity of the printing surface becomes a problem, for example, the ink is repelled at a part and a part without ink is generated.

The present invention therefore overcomes these drawbacks,
It has excellent ink absorption capacity for high-speed printing and high ejection volume inkjet systems, and also has excellent color development and resolution, and has a uniform printing surface with a coating layer to prevent uneven printing. The present invention aims to provide a new inkjet recording material.

[0008]

The present invention relates to an ink jet recording material having a coating layer provided on a base paper, wherein a pigment having an average particle diameter of 3 μm or less, a water-soluble binder, and The inkjet recording material is characterized in that a nonionic surfactant having an HLB value in the range of 7 to 9 is blended at a ratio of 0.05 to 0.5% by weight with respect to the pigment. Further, the present invention is characterized in that the nonionic surfactant is a polymer containing an ethylene oxide unit (C ₂ H ₄ O). Further, the ink jet recording material of the present invention is a pigment according to JIS-P8122. Human coating with a sizing degree of 10 seconds or less, with a dry coating amount of 3 to 1
It is an inkjet recording material provided with a coating layer by coating in the range of ² g / m ² .

It is considered that the coating layer on the base paper may be thickened in order to enhance the ink absorbing ability in response to an ink jet system of high speed printing and high ejection amount. However, the recording material coated with a thick coating layer feels different from plain paper, and when the recording material is bent, the coating layer is cracked or peeled (hereinafter referred to as "folding") or powder. There is a need for a recording material coated as thinly as possible because it easily falls off, and powder easily falls off during transportation of the paper inside the printer, causing problems such as nozzle clogging.

On the other hand, when the coating layer is made thin, the fibers of the base paper are not completely covered with the coating layer, and the fibers are exposed in places,
It becomes difficult to apply the coating layer itself evenly, and the coating layer becomes uneven. When fibers are exposed or uneven in the coating layer in this way, the ink is repelled at that portion to form a white portion where the ink does not stay, and a white portion that is not colored on the printed surface (hereinafter referred to as “white petit”). ) Will be scattered, and the image quality will deteriorate.

The white petit is a case where the uniformity of the printed surface in the coating layer is impaired due to uneven distribution of pigment components in the coating layer, in addition to the exposure of fibers and unevenness of the coating layer as described above. In addition, it is thought that this is caused by the fact that the ink is not well compatible with the base paper and the pigment, and the ink is repelled. Therefore, if the coating layer is formed using a pigment having a large particle size in order to improve the coatability of the coating liquid, it is possible to suppress the generation of white petites to some extent, although it is not perfect. However, the image quality is greatly affected by the particle size of the pigment used in the coating layer, and when a pigment having such a large particle size is used, the image characteristics such as ink absorption and color developability deteriorate. Furthermore, in a coating layer composed of a pigment having such a large particle size, powder is likely to fall off even though the coating layer is formed thin, which causes a fatal defect. I understood. Furthermore, in order to prevent powder falling, if the amount of binder is increased and the coating layer is formed with a binder amount that does not cause powder falling, the image characteristics such as ink absorption and resolution will deteriorate further. It will be unusable for practical use.

Therefore, as a result of various studies on the particle size of the pigment, the image characteristics, and the presence or absence of powder drop, powder drop occurs when a thin coating layer is formed using an amount of binder that does not impair ink absorbency. It was found that, in order to form a coating layer having excellent image quality without using a pigment, a pigment having an average particle diameter of 3 μm or less can be used to obtain preferable results. Therefore, it is necessary to use a pigment having an average particle diameter of 3 μm or less in order to prevent powder falling and deterioration of image quality, and further to prevent white petit generated when a pigment having such a fine particle diameter is used. become. On the other hand, the inventors of the present invention can uniformly coat the printed surface of the coating layer by adding a surfactant to the coating layer formed of a pigment and an aqueous binder. It has been found that the occurrence of the above can be prevented, and the present invention has been completed based on this.

Hereinafter, the present invention will be described in detail. The particle size of the pigment used in the present invention is a pigment having an average particle size of 3 μm or less as described above. When it exceeds 3 μm, powder is liable to be generated as described above, and the surface of the coating layer tends to be rough so that smoothness is deteriorated and image characteristics are also deteriorated. It should be noted that all the pigments forming the coating layer used in the present invention need not be pigments having an average particle size of 3 μm or less, and have an average particle size of 3 μm or more to the extent that powder drop and deterioration of image characteristics do not occur. A pigment can be mixed and used.

Examples of the pigment forming the coating layer used in the present invention include inorganic materials such as silica, calcium carbonate, talc, titanium dioxide, zinc oxide, magnesium carbonate, aluminum silicate, aluminum hydroxide, alumina and pseudoboehmite. There are white pigments of the type, and these can be used alone or in combination of two or more kinds. Especially BE
T specific surface area is 100 to 400 m ² / g, oil absorption is 150
When silica or / and alumina in the range of up to 300 ml / 100 g is used, preferable results can be obtained in terms of image density (color developability) and resolution.

The surfactant used in the present invention is preferably a nonionic surfactant. Among them, those having an ethylene oxide unit (C ₂ H ₄ O) in the molecule particularly prevent the generation of white petit and absorb the ink. It is preferable in that the property is improved. Cationic, anionic and amphoteric surfactants having an ionic group in the molecule have a low ability to suppress the generation of white petit and tend to not achieve the uniformity of the printed surface. The ability to improve also tends to be low.

The HLB (hydrophile-lipophile balance) value of the surfactant is very important for preventing the generation of white petit, and it is necessary that it be in the range of 7 to 9, and this value is less than 7. Or, in any case where it exceeds 9, white petites are likely to occur, and the uniformity of the printed surface tends to decrease,
Further, there is a tendency that the ability to improve the ink absorbency is low. This indicates that a certain balance of hydrophilic and lipophilicity is required in order to impart compatibility with the ink due to the relationship with the base paper and pigment used. Further, it has been shown that a certain value is preferable for improving the ink absorbency in view of the relationship with the base paper, the binder and the like. As the nonionic surfactant having such an HLB value, commercially available products such as Epan 420 and Epan 720 (both are trade names, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) can be used.

The content of the surfactant is 0.05 to 0.5% by weight based on the pigment in the coating liquid, and the surfactant is mixed with the pigment and the binder to prepare the coating liquid. Also,
It is also possible to prepare a coating liquid by mixing a pigment and a binder, and then add a surfactant to prepare the coating liquid. If the compounding amount is less than 0.05% by weight, the effect is small and 0.5
If it exceeds 5% by weight, the powder tends to fall off and the tint of the mixed color portion tends to decrease.

As described above, when a surfactant is added to the coating liquid, the wettability of the coating liquid is improved and a uniform coating layer can be easily formed. It is considered that the surface condition of the pigment is changed, and the ink becomes compatible with the fibers and the irregularities of the coating layer itself, making it easier to wet and eliminating the white petit.

Further, since the coating liquid itself containing the surfactant also wets the base paper well, the binder component which is a water-soluble component in the coating liquid is more easily absorbed by the base paper. As a result, the amount of the binder component near the surface of the coating layer is smaller than that in the absence of the surfactant, and the micropores in the pigment that are covered with the binder and cannot participate in the ink absorbability are exposed. When this happens,
It is considered that the micropores act as capillaries in the coating layer to further enhance the ink absorbability, and at the same time, the dye in the ink can be trapped on the pigment surface near the surface of the coating layer to improve the fixing property.

A water resistance improver may be added to the coating layer of the ink jet recording material, if necessary, in order to prevent bleeding or the like when the recording paper is splashed with water. May be. Such a water resistance improver is generally a polycationic polymer and imparts water resistance by forming a salt with a carboxylic acid group or a sulfonic acid group in the dye of the ink in the coating layer to make it insoluble. To do. As such a water resistance improver, for example, polyvinyl pyridine, polyvinyl imidazole, polyethylene imine, polyvinyl amine, polyallyl amine, polyallyl amine sulfone, polyamine sulfone, or ammonium salts thereof can be used. These water resistance improvers can achieve the purpose generally in an amount of 20% by weight or less based on the solid content in the coating layer.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The ink jet recording material of the present invention is prepared by adding a water resistance improver to the above-mentioned pigment, if necessary, and mixing it with a binder and a surfactant. It is prepared by coating and drying.

The base paper used in the present invention includes papers such as coated papers, recycled papers, fine papers and art papers. The sizing degree of paper affects the absorbability of ink during recording, and the sizing degree of the base paper is JI.
Preferable results are obtained by using those having a Steckigt sizing degree of 0 to 10 seconds according to SP8122. If the sizing degree exceeds 10 seconds, a high-quality image cannot be obtained unless the ink absorption is increased by forming a thick coating layer. Will occur.

The binder used is not particularly limited as long as it is a water-soluble polymer having binding ability, and examples thereof include polyvinyl alcohol, starch, gelatin, casein, gum arabic, sodium alginate, Examples include carboxymethyl cellulose and sodium polyacrylate.

In the present invention, by adding the surfactant as described above, the binder component is easily absorbed by the base paper and the binder component in the coating layer is reduced, so that the surfactant is added. Compared to the case where it is not done, a little more binder will have to be added,
In general, the amount of the binder compounded is preferably 10 to 200% by weight based on the total amount of the pigment forming the coating layer,
Particularly, in the range of 20 to 100% by weight, preferable results can be obtained from the viewpoint of ink absorbing ability. If the amount is less than 10% by weight, the pigment cannot be adhered to the base paper, and
If it exceeds 0% by weight, the ink absorbency tends to decrease, and the resolution tends to decrease.

For coating, a known coating device such as an air knife coater, a blade coater, a cast coater is used,
The drying can be performed using a known drying device such as a hot air drier, a heat drum, a far infrared ray drier.

The coating amount is related to the ink absorptivity of the recording material. When the coating amount is large and the coating layer is thick, the ink absorptivity and resolution are improved, but the image density is The coated layer will be peeled off, powder will fall off, etc., and the touch will be different from that of plain paper. Therefore, it is preferable to apply as thinly as possible, and the solid content is 3 to 12 g.
Good results are obtained by coating in the range of / m ² . When the coating amount is less than 3 g / m ² , the coating layer cannot be sufficiently formed, and the image density and resolution are lowered, resulting in 12 g / m 2.
^When it exceeds ² , the touch feeling is different from plain paper, and there is a tendency that breakage is likely to occur.

Further, when preparing a coating liquid, a pigment dispersant, a water retention agent, a water resistance agent, a thickener, a release agent, a lubricant, a fluorescent dye, an ultraviolet absorber, and a writability are improved as necessary. Various additives such as agents can be appropriately used in combination.

Further, in order to further smooth the surface of the coating layer and improve the surface strength, after the coating layer is provided, it is treated with a super calender, a gloss calender, etc. to the extent that the ink absorbency is not deteriorated. It doesn't matter.

The above-mentioned recording material according to the present invention can be applied to water-based ink generally used for ink jet recording. The components of such an ink are, for example, 1 to 5% by weight of a dye such as an acid dye or a direct dye, and 5 to 60% by weight of a water-soluble high-boiling point organic solvent such as diethylene glycol for preventing nozzle clogging.
And 30 to 80% by weight of water.

[0030]

EXAMPLES The present invention will be described in more detail below with reference to experimental examples. The characteristics of the pigments used in the experimental examples for the explanation are shown in Table 1 collectively.

[0031]

[Table 1]

Experimental Example 1 100 parts by weight of synthetic amorphous silica (trade name: Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.) as a white pigment, polyvinyl alcohol (trade name: PVA-11) as a binder.
7, manufactured by Kuraray Co., Ltd., 30 parts by weight, a polyallylamine type cationic resin (trade name: PAA-3L, as a water resistance improver,
Water is added to 10 parts by weight of Nitto Boseki Co., Ltd. and mixed, and nonionic surfactant polyethylene polypropylene glycol ether (trade name: Epan 420, HLB: 9, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) is further added as a surfactant. Add 0.01% by weight to the pigment and continue mixing to obtain a solid content of 20%.
The coating liquid was prepared so as to have a weight percentage. The obtained coating liquid has a Steckigt sizing degree of 7 according to JIS-P8122.
Using a bar coater on the second base paper, the dry coating amount is 7 g /
It is coated so that it becomes m ² and dried with a hot air dryer (110
(° C, 5 minutes) to form a coating layer. After that, calendar processing was performed to produce an inkjet recording material.

The recording material thus obtained was evaluated according to the following method, and the evaluation results are shown in Table 2.

Evaluation method 1. Recording method Color copier (Product name: BJ-A1 Pixel Pro, 4
00 dpi, manufactured by Canon Inc. and color bubble jet Copier (registered trademark) -1 dedicated ink (black: Bk, cyan: C, magenta: M, yellow: Y,
It was printed by using Canon Inc.).

2. Monochromatic optical density The optical density (OD) of a monochromatic black recorded portion was measured using a Macbeth densitometer (product name: RD-918, manufactured by Macbeth Co.) and evaluated according to the following criteria. ○ When the optical density (OD) is 1.50 or more. Δ When the optical density (OD) is 1.35 or more and less than 1.50. × When the optical density (OD) is less than 1.35.

3. Mixed color tint 200 consisting of 100% cyan and 100% magenta
The optical density (OD) of magenta in the% blue solid recorded portion was measured using a Macbeth densitometer (product name: RD-918, manufactured by Macbeth Co.) and evaluated according to the following criteria. ○ When the optical density (OD) is 1.45 or more. Δ When the optical density (OD) is 1.40 or more and less than 1.45. × When the optical density (OD) is less than 1.40.

4. Folding Breaking The unrecorded recording material was folded in two, and the folds were rubbed three times with a weight of 500 g, and the degree of peeling of the coating layer and the degree of fiber exposure were visually determined according to the following criteria. ○ Peeling of the coating layer and no exposed fibers are observed. × Peeling of the coating layer and exposure of fibers are observed.

5. Uniformity of printed surface Visually observing the recording area of monochromatic black by three panelists, "○" when two or more panelists judge that there is no "white petit", and "x" otherwise. And

6. Ink absorbency Using a Bristow tester (manufactured by Toyo Seiki Co., Ltd.), ink absorbency (x) at a contact time of 0.01 seconds was measured and evaluated according to the following criteria. ○ When the ink absorbency (x) is 20 ml / m ² or more. Δ When the ink absorbency (x) is 18 ml / m ² or more and less than 20 ml / m ² . × When the ink absorbency (x) is less than 18 ml / m ² .

7. Water resistance: The optical density of the recorded portions of black and magenta was measured using a Macbeth densitometer (Product name: RD-9
18, manufactured by Macbeth), and the optical density residual ratio (ROD) according to the following equation using the optical density before and after immersion.
(%) Was determined, and when the optical density residual ratio (ROD) was 100% or more for both black and magenta, it was designated as “◯”, and the other cases were designated as “x”.

[0041]

## EQU1 ## ROD (%) = (OD after immersion / O before immersion)
D) x 100

8. Powder drop The surface of the recording material was lightly rubbed with a finger, and the state of powder drop was visually evaluated according to the following criteria. ○ No powder drop was observed. Δ A slight powder drop is observed when rubbed strongly, but this is not a problem in practical use. × The powder is so bad that the coating layer is destroyed.

[0043]

[Table 2]

[0044]

[Table 3]

[0045]

[Table 4]

[0046]

[Table 5]

Experimental Example 2 An ink jet recording material was prepared and evaluated in the same manner as in Experimental Example 1 except that the amount of the nonionic surfactant (Epan 420) added was changed to 0.2% by weight based on the pigment. Table 2
Shown in

Experimental Example 3 An ink jet recording material was prepared and evaluated in the same manner as in Experimental Example 1 except that the amount of the nonionic surfactant (Epan 420) added was changed to 0.5% by weight based on the pigment. Table 2
Shown in

Experimental Example 4 An ink jet recording material was prepared and evaluated in the same manner as in Experimental Example 1 except that the amount of the nonionic surfactant (Epan 420) added was changed to 0.8% by weight based on the pigment. Table 2
Shown in In addition, in the table, "-" in the evaluation results indicates that the powder drop of the obtained inkjet recording material is bad,
This is because it was not necessary to evaluate the printed recording material.

Experimental Example 5 Using the coating liquid prepared in Experimental Example 2, JIS-P8122 was used.
Was applied to a base paper having a Steckigt sizing degree of 7 seconds using a bar coater so that the dry coating amount was 30 g / m ^2, and an inkjet recording material was prepared in the same manner as in Experimental Example 1 and evaluated. The results obtained are shown in Table 2.

Experimental Example 6 Using the coating liquid prepared in Experimental Example 2, JIS-P8122 was used.
Was applied to a base paper having a Steckigt sizing degree of 7 seconds using a bar coater so that the dry coating amount was 2 g / m ^2, and an inkjet recording material was prepared in the same manner as in Experimental Example 1 and evaluated. The results obtained are shown in Table 2.

Experimental Example 7 The surfactant to be added was replaced with another nonionic surfactant polyethylene polypropylene glycol ether (trade name: Epan 485, HLB: 20, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and the added amount was changed to a pigment. On the other hand, the content was set to 0.2% by weight, an inkjet recording material was prepared in the same manner as in Experimental Example 1, and the evaluation results are shown in Table 2.

Experimental Example 8 The surfactant to be added was replaced with another nonionic surfactant polyethylene polypropylene glycol ether (trade name: Epan 720, HLB: 7, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.),
The amount to be added was 0.2% by weight with respect to the pigment, and Experimental Example 1
An ink jet recording material was prepared in the same manner as in 1. and the evaluation results are shown in Table 2.

Experimental Example 9 As the surfactant to be added, another polyglycol-based nonionic surfactant (trade name: Antifloss F-233, HL) was used.
B: 6, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., and the addition amount was 0.2% by weight based on the pigment, an inkjet recording material was prepared in the same manner as in Experimental Example 1, and the evaluation results are shown in Table 2. Show.

Experimental Example 10 The surfactant to be added was replaced with an anionic surfactant polyoxyethylene alkyl ether phosphate (trade name: Plysurf A208S, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.),
The amount to be added was 0.2% by weight with respect to the pigment, and Experimental Example 1
An ink jet recording material was prepared in the same manner as in 1. and the evaluation results are shown in Table 3.

Experimental Example 11 The surfactant to be added was replaced with the cationic surfactant alkyltrimethylammonium claride (trade name: Cationogen L, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and the addition amount was 0.2 with respect to the pigment. Table 3 shows the results of evaluation by making an ink jet recording material in the same manner as in Experimental Example 1 with the content being wt%.

Experimental Example 12 The surfactant to be added was replaced with an imidazoline type amphoteric surfactant (trade name: Amogen No. 8, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and the amount added was 0.2% by weight based on the pigment. %, A recording material for inkjet recording was prepared in the same manner as in Experimental Example 1, and the evaluation results are shown in Table 3.

Experimental Example 13 An ink jet recording material was prepared in the same manner as in Experimental Example 1 by preparing a coating liquid without adding a surfactant, and the evaluation results are shown in Table 3.

Experimental Example 14 A coating solution was prepared without adding a surfactant, and JIS-P8 was used.
122 was applied to a base paper having a Steckigt sizing degree of 22 seconds so that the dry coating amount was 7 g / m ² , an inkjet recording material was prepared in the same manner as in Experimental Example 1, and the evaluation results are shown. 3 shows. In addition, in the table, "-" is because the ink absorbency was poor and an image worthy of evaluation was not obtained.

Experimental Example 15 A non-ionic surfactant (Epan 420) was used in which vapor phase alumina (trade name: aluminum oxide-C, manufactured by Nippon Aerosil Co., Ltd.) was used in place of the synthetic amorphous silica as the white pigment, and was added. The amount of was changed to 0.2% by weight relative to the pigment, an inkjet recording material was prepared in the same manner as in Experimental Example 1, and the evaluation results are shown in Table 4.

Experimental Example 16 A coating solution was prepared by adding vapor phase method alumina (trade name: aluminum oxide-C, manufactured by Nippon Aerosil Co., Ltd.) in place of synthetic amorphous silica as a white pigment, without adding a surfactant. Table 4 shows the results of the preparation, the production of the ink jet recording material, and the evaluation thereof.

Experimental Example 17 Amorphous silica (trade name: Fineseal X-37, TOKUYAM, synthesized by replacing white pigment with synthetic amorphous silica)
(Manufactured by Company A) was used, and the amount of the nonionic surfactant (Epan 420) added was changed to 0.2% by weight with respect to the pigment, and an inkjet recording material was prepared in the same manner as in Experimental Example 1, The evaluation results are shown in Table 4.

Experimental Example 18 Synthetic amorphous silica (trade name: Fineseal X-37, TOKUYAM in place of synthetic amorphous silica in place of white pigment)
Table A shows the results of evaluation by preparing an inkjet recording material in the same manner as in Experimental Example 1 by preparing a coating liquid using a product manufactured by Company A) without adding a surfactant.

Experimental Example 19 Instead of the synthetic amorphous silica as the white pigment, another synthetic amorphous silica (trade name: Sylysia 450, manufactured by Fuji Silysia Ltd.) was used, and a nonionic surfactant (Epan 420) was added. The amount of was changed to 0.2% by weight relative to the pigment, an inkjet recording material was prepared in the same manner as in Experimental Example 1, and the evaluation results are shown in Table 4. In addition, in the table, the evaluation result of "-" is because the obtained ink-jet recording material does not easily fall off and it is not necessary to evaluate the printed recording material.

Experimental Example 20 Instead of the synthetic amorphous silica as the white pigment, another synthetic amorphous silica (trade name: Sylysia 450, manufactured by Fuji Silysia Ltd.) was used, and a coating solution was prepared without adding a surfactant. Prepared,
An inkjet recording material was prepared in the same manner as in Experimental Example 1, and the evaluation results are shown in Table 4.

Experimental Example 21 100 parts by weight of synthetic amorphous silica (trade name: Aerosil 200, manufactured by Nippon Aerosil Co., Ltd.) as a white pigment, polyvinyl alcohol (trade name: PVA-11) as a binder
7. Kuraray Co., Ltd.) 30 parts by weight of water was added and mixed, and as a surfactant, a nonionic surfactant polyethylene polypropylene glycol ether (trade name: Epan 420, HLB: 9, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) Was added to the pigment in an amount of 0.2% by weight, and mixing was continued to prepare a coating solution so that the solid content concentration was 20% by weight. The obtained coating liquid has a Steckigt sizing degree of 7 according to JIS-P8122.
Using a bar coater on the second base paper, the dry coating amount is 7 g /
It is coated so that it becomes m ² and dried with a hot air dryer (110
(° C, 5 minutes) to form a coating layer. After that, calendar processing was performed to produce an inkjet recording material. The obtained recording material was evaluated in the same manner as in Experimental Example 1.
Table 5 shows the results.

Experimental Example 22 An inkjet recording material was prepared and evaluated in the same manner as in Experimental Example 21 except that the amount of the nonionic surfactant (Epan 420) added was changed to 0.5% by weight based on the pigment. Is shown in Table 5.

Experimental Example 23 The surfactant to be added was replaced with another nonionic surfactant polyethylene polypropylene glycol ether (trade name: Epan 485, HLB: 20, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and the added amount was changed to a pigment. On the other hand, the content was set to 0.2% by weight, an inkjet recording material was prepared in the same manner as in Experimental Example 21, and the evaluation results are shown in Table 5.

Experimental Example 24 The surfactant to be added was replaced with another nonionic surfactant polyethylene polypropylene glycol ether (trade name: Epan 720, HLB: 7, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.),
The amount to be added was 0.2% by weight with respect to the pigment, and Experimental Example 2
An inkjet recording material was prepared in the same manner as in No. 1, and the evaluation results are shown in Table 5.

Experimental Example 25 Other polyglycol-based nonionic surfactants (trade name: Antifloss F-233, HL) were added as surfactants.
B: 6, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., and the addition amount was 0.2% by weight based on the pigment, an inkjet recording material was prepared in the same manner as in Experimental Example 21, and the evaluation results are shown in Table 5. Show.

Experimental Example 26 The surfactant to be added was replaced with an anionic surfactant polyoxyethylene alkyl ether phosphate (trade name: Plysurf A208S, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.),
The amount to be added was 0.2% by weight with respect to the pigment, and the experimental example 2 was used.
An inkjet recording material was prepared in the same manner as in No. 1, and the evaluation results are shown in Table 5.

Experimental Example 27 The surface active agent to be added was replaced with a cationic surface active agent alkyltrimethylammonium claride (trade name: Cationogen L, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and the addition amount was 0.2 with respect to the pigment. The ink-jet recording material was produced in the same manner as in Experimental Example 21, and the evaluation results are shown in Table 5.

Experimental Example 28 The surfactant to be added was replaced by an imidazoline type amphoteric surfactant (trade name: Amogen No. 8, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and the addition amount was 0.2% by weight based on the pigment. %, And an evaluation result is shown in Table 5.

Experimental Example 29 An ink jet recording material was prepared in the same manner as in Experimental Example 21 by preparing a coating liquid without adding a surfactant, and the evaluation results are shown in Table 5.

From the results of Tables 2 to 4, it can be seen that when the water resistance improver is used, the addition of the surfactant increases the ink absorbability of the coating layer and improves the fixability. This is because, as described above, the addition of the surfactant made it easier for the binder, which is a water-soluble component in the coating liquid, to be absorbed by the base paper, so that the binder component around the pigment particles near the surface of the coating layer decreased. The reason is that the micropores of the pigment itself can absorb the ink as capillaries. Therefore, when the amount of the surfactant added is increased, this tendency is further advanced, the amount of the binder component around the pigment is further decreased, and the ink absorbability, that is, the fixing property is improved, but the pigment is sufficiently bound. Is no longer possible and the powder is now falling off, and the coating layer can no longer be formed (Experimental Example 4). Thus, it can be seen that the amount of surfactant added is subject to certain restrictions.

The above is greatly affected by the particle size of the pigment used, and the finer the pigment particles, the more convenient it is to bind the pigment with a small amount of the binder component. Addition of a small amount of surfactant causes powder to fall off, making it impossible to form a coating layer (Experimental Example 19). Thus, it is understood that the amount of the surfactant added is influenced by the particle size of the pigment used, and that the amount of the surfactant needs to be reduced when using a pigment having a large particle size.

On the other hand, the uniformity of the printed surface, that is, the presence / absence of white petits, varies depending on the type of surfactant. That is, it can be seen that when a nonionic surfactant among the surfactants is used, white petit is not generated and the uniformity of the printed surface is excellent. Furthermore, this effect also shows that as the amount of the nonionic surfactant added increases, the occurrence of white petites disappears, contributing to the improvement of the uniformity of the printed surface. Also in this case, if a large amount is added, the coating layer cannot be formed as described above (Experimental Example 4), and it is understood that adding a large amount is not preferable for producing an inkjet recording material.

This is because the nonionic surfactant having no electric charge is not affected by the electric charge in the coating layer and uniformly modifies the fiber or pigment surface of the base paper to be hydrophilic, so that it is compatible with the ink. It seems to make it easier. However, in the coating liquid system used in this experiment, a surfactant having an HLB of about 7 to 9 and not so hydrophilic was effective for this surface modification.

Regarding the coating amount, it can be seen that when the coating amount is increased, cracking occurs, and a problem occurs when the coating layer is thickened. Further, it can be seen that the optical density of printing is lowered by increasing the thickness of the coating layer (Experimental Example 5). It is considered that this is because the ink applied to the thick coating layer diffuses in the layer and the dye in the ink is not trapped only in the surface layer but spreads widely. In addition, when the coating layer is thinned, the ink that has been imprinted cannot be absorbed by the coating layer alone and is also absorbed by the base paper, so the dye in the ink spreads toward the base paper. Therefore, the optical density will decrease. Therefore, as in the present invention, when using a base paper that has a low Steckigt sizing degree and is easily absorbed, the dye of the ink is trapped near the surface of the coating layer, and only excess water is absorbed by the base paper. It is important to produce an inkjet recording material with such a coating amount. In the case of the present invention, the coating amount is 3 to 12 g
It can be seen that / m ² is optimal.

Further, from the results in Table 5, it is found that when the water resistance improver is not used, the ink absorptivity is improved when the nonionic surfactant having HLB of about 7 to 9 is used. . As described above, the reason why only a specific surfactant is effective is not clear, but even in a system in which a water resistance improver which is a polycation does not exist, the charge of the surfactant or the hydrophilic-hydrophobic balance influences. It is considered that

In order to improve the uniformity of the printed surface when a nonionic surfactant having an HLB of about 7 to 9 is used, the evaluation method of visually observing the presence / absence of white petit is Even if not, there is no white petit,
Although there is no difference in data from the case of using other types of surfactants, the coated surface is extremely smooth and the printed surface is more uniform than when other surfactants or surfactants are not used. The nature was high.

Next, the magnitude of the effect of the nonionic surfactant having an HLB of about 7 to 9 used in the present invention will be described with reference to Table 6. Table 6 shows the uniformity of the printed surface and the ink when a nonionic surfactant having an HLB of about 7 to 9 and other surfactants were used, both with and without the use of the water resistance improver. The effect of the above on the absorbability is compared with the case where no surfactant is added (Experimental Examples 13 and 29). That is, from the evaluation value in the absence of a surfactant, two ranks up (× → ○) were evaluated as “◎”, and one rank up (X → △, △ → ○) were evaluated as “○”, to the same degree ( If it was × → ×, △ → △, ○ → ○), it was “△”, or decreased (○ → △, ○ → ×, △ →
In the case of x), "x" represents the magnitude of the effect of each surfactant.

[0083]

[Table 6]

From the results shown in Table 6, regarding the uniformity of the printed surface and the ink absorbency, the non-ionic surfactant having an HLB of about 7 to 9 was added to the printed surface to make the printed surface uniform regardless of the presence or absence of the water resistance improver. It can be seen that the property and the absorbability of the ink are improved. The combined use of the water resistance improver tends to deteriorate the uniformity of the printed surface, but when the water resistance improver is used, the effect of the addition of the nonionic surfactant having an HLB of about 7 to 9 is large. It appears remarkably, and an inkjet recording material having excellent water resistance can be obtained.

The reason for this is not clear, but it can be considered as follows based on the amount of the substance having a charge present in the coating layer. That is, it is considered that the white petit is caused not only by the physical uniformity of the coated surface but also by the interaction between the charge or polarization of the dye in the ink and the charge contained in the coating layer. Under such circumstances, the water resistance improver used in the present invention is generally a polycationic polymer containing a large number of ammonium salts, and a large number of cations and anions that are counterions are contained in the coating layer. Since it exists, white petites are likely to occur. Therefore, it is considered that anionic, cationic, and amphoteric surfactants having a charge, such as an amphoteric surfactant, do not reduce the charge in the coating layer, but rather increase the charge. It is in a state where it easily occurs.

On the other hand, in the case of the nonionic surfactant, since it has no electric charge, the electric charge in the coating layer is not further increased. In addition, among them, nonionic surfactants having a relatively high lipophilicity can interact with the water resistance improver, thereby reducing the influence of electric charge by shielding ammonium salts, and the like. By reducing the amount of electric charge, it is considered that the occurrence of white petit is prevented. However, when the lipophilicity of the surfactant is too strong, it tends to repel water, which is the solvent of the ink, and white petites are likely to occur. Further, when the hydrophilicity is strong, the surfactant itself has polarization, and the power of the water resistance improver for canceling the charge is weak, and it is considered that it is impossible to suppress the generation of white petit. As a preferable degree of hydrophilicity and lipophilicity, it is found from the results of a series of experiments that HLB of 7 to 9 is preferable.

When no water resistance improver is used,
Since there is no electric charge in the coating layer, white petit caused by the interaction with the electric charge does not occur. Furthermore, even if a charged anionic, cationic, or amphoteric surfactant is added, the addition amount of these is small, the electric charge existing in the coating layer is small, and the occurrence of white petit is not affected. Probably not given.

As described above, with respect to the absorbability of the ink, the addition of the surfactant facilitates the absorption of the binder, which is a water-soluble component in the coating liquid, into the base paper, and the micropores of the pigment itself contribute to the absorption of the ink. The surfactant most suitable for this action was a nonionic surfactant having an HLB of 7 to 9, as can be seen from the experimental results. However, when a polycationic polymer that is a water resistance improver is present in the coating liquid, any of anionic and cationic surfactants, and nonionic surfactants having HLB other than 7 to 9 are used. However, as a result of these surfactants interacting with the water resistance improver in some way, the HLB exhibits the same action as the nonionic surfactant having 7 to 9 and the ink absorbability is improved. It seems to be.

[0089]

EFFECTS OF THE INVENTION According to the present invention, by adding a nonionic surfactant having an HLB of about 7 to 9 to a coating liquid, the printed surface of the coating layer is uniformly coated and the occurrence of white petit is prevented. In addition, the ink absorbency is improved. In addition, a pigment having an average particle size of 3 μm or less is used, and a Steckigt sizing degree of 3 to 12 g / m is applied to a base paper having a sizing degree of 10 seconds or less.
^By coating with a coating amount of ² , it has an excellent ink absorption capacity for high ejection volume inkjet systems, as well as excellent color development and resolution, and a coating layer that prevents uneven printing. A high-quality inkjet recording material having a uniform printing surface can be obtained.

Claims (3)

[Claims] 1. An ink jet recording material having a coating layer provided on a base paper, wherein a pigment having an average particle diameter of 3 μm or less, a water-soluble binder, and an HLB value in the range of 7 to 9 are contained as components of the coating layer. An ink jet recording material in which the nonionic surface active agent is mixed with the pigment in an amount of 0.05 to 0.5% by weight. 2. The ink jet recording material according to claim 1, wherein the nonionic surfactant is a polymer containing an ethylene oxide unit (C ₂ H ₄ O). 3. A dry coating amount of 3 to 1 is applied to a base paper having a Steckigt sizing degree of 10 seconds or less according to JIS-P8122.
The inkjet recording material according to claim 1 or 2, which is coated in a range of ² g / m ² .