JP2003305947A - Ink jet recording sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet recording sheet especially excellent in the water resistance of an image, the water resistant of an ink receiving layer and image density while having the fundamental characteristics of the conventional ink jet recording sheet and suitable for outdoor use such as a poster or the like. <P>SOLUTION: The ink jet recording sheet is constituted by providing the ink receiving layer on a support. The ink receiving layer is a layer with a pH of <6.5 formed by applying an ink receiving layer forming material containing a hydrophobic anionic acrylic resin, which shows poor solvent or non-solvent properties with respect to a solvent in aqueous ink, as a binder and drying the formed layer. This image receiving layer is impregnated with an addition polymer of dimethylamine and epichlorohydrin. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an ink jet recording sheet, and more specifically, it has an ink receiving layer on a substrate and is excellent in water resistance of the ink receiving layer, water resistance of an image and image density. The present invention relates to an inkjet recording sheet suitable for outdoor use such as posters.

[0002]

2. Description of the Related Art In recent years, due to the widespread use of computers, it has become common to print out materials created by computers using printers and the like. As a printer used at that time,
Dot impact printers, laser printers, thermal printers, inkjet printers and the like can be mentioned, but inkjet printers are widely used because they have almost no mechanical noise at the time of printing out and the running cost associated with printing out is low.

In such an ink jet recording system, a recording sheet having an ink receiving layer provided on a base material is used. With the expansion of applications, not only image accuracy but also water resistance is required. ing. As the binder of the ink receiving layer, a cationic resin is often used,
There is also a method of using an anionic resin in order to improve the water resistance of the ink receiving layer. However, when an anionic resin is used, the water resistance of the layer itself can be obtained, but the water resistance of the image deteriorates, and especially when used outdoors as a poster, the water resistance of the image becomes insufficient. There was a problem. As a method of improving the water resistance of this image, it has been proposed to add an addition polymer of dimethylamine and epichlorohydrin (Japanese Patent Laid-Open No. 6-201212), but an anionic resin is used as a binder. When an addition polymer of dimethylamine and epichlorohydrin is added to the coating liquid, the coating liquid may gel and the image density is insufficient. The present inventor previously found that the layer formed by applying and drying the ink-receiving layer forming material containing no addition polymer of dimethylamine and epichlorohydrin was added to the layer formed by addition polymerization of dimethylamine and epichlorohydrin. By impregnating the product, a method has been proposed in which the ink receiving layer contains an addition polymer of dimethylamine and epichlorohydrin without causing the problem of gelation of the coating liquid.
Even with this method, although the water resistance of the ink receiving layer and the water resistance of the image are excellent, the image density is not always satisfactory.

[0004]

Under the circumstances, the present invention provides not only the water resistance of the ink receiving layer and the water resistance of the image while having the basic characteristics of the conventional ink jet recording sheet. It is an object of the present invention to provide an inkjet recording sheet excellent in image density.

[0005]

The present inventor has conducted extensive studies to develop an ink jet recording sheet having the above-mentioned excellent properties, and as a result, as a binder, it is poor against the solvent in the aqueous ink. By using a hydrophobic and anionic acrylic resin exhibiting a solvent or non-solvent property and adjusting the pH of the layer before impregnating the addition polymer of dimethylamine and epichlorohydrin to less than 6.5 , Found that they could achieve that goal. The present invention has been completed based on such findings.

That is, according to the present invention, an ink receiving layer is provided on a substrate, and the ink receiving layer exhibits a poor solvent property or a non-solvent property with respect to the solvent in the aqueous ink, and is hydrophobic and anionic. The pH formed by applying and drying the ink receiving layer forming material using the acrylic resin as a binder is 6.
It is intended to provide an inkjet recording sheet characterized in that a layer having a number of less than 5 is impregnated with an addition polymer of dimethylamine and epichlorohydrin.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The ink jet recording sheet of the present invention has an ink receiving layer on at least one surface of a substrate. In the present invention, the base material is not particularly limited as long as it is in the form of a sheet.
Various materials such as plastic films, papers, non-woven fabrics and the like can be used, but plastic films are particularly preferable from the viewpoint of water resistance. The material of the plastic can be selected from general thermoplastic resin films such as vinyl chloride, polyethylene terephthalate, polypropylene, polystyrene and polycarbonate, or those in which inorganic powder such as calcium carbonate is internally added. .

Foamed plastic films can also be used. Here, the foamed plastic film refers to a plastic film having cracks or voids formed on the surface or inside of the film, or fine bubbles or cavities, and these bubbles or cavities include those such as calcium carbonate. A film containing inorganic powder is stretched to be generated around the inorganic powder (micro void film), or a film containing a foaming agent is formed by foaming a foaming agent. The form of formation of bubbles or cavities does not matter. The plastic film referred to here also includes what is called synthetic paper.

The substrate may have a single-layer structure or a multi-layer structure,
As the multilayer structure, for example, a method of laminating layers via an adhesive, a so-called co-extrusion method of extruding a plurality of raw materials from a plurality of extruders to join and form a film, a film directly from an extruder on a film. The so-called extrusion laminating method of laminating by laminating while extruding,
Those formed by any known method can be used.

If desired, one or both surfaces of the substrate may be subjected to a surface treatment by an oxidation method or a concavo-convex method for the purpose of improving the adhesion or wettability with the ink receiving layer or the like. . Examples of the oxidation method include corona discharge treatment and hot air treatment, and examples of the uneven method include sandblasting method and solvent treatment method. These surface treatment methods are appropriately selected according to the type of the base material, but in general, the corona discharge treatment method is preferably used in terms of effects and operability. Also, an easy adhesion treatment can be applied.

In the present invention, the ink receiving layer provided on at least one surface of the base material is a binder.
It contains a hydrophobic and anionic resin that exhibits a poor solvent property or a non-solvent property with respect to the solvent in the aqueous ink. Among these resins, the use of acrylic resin is one of the features of the present invention. When the hydrophobic and anionic resin exhibiting a poor solvent property or a non-solvent property with respect to the solvent in the water-based ink is an acrylic resin, when a filler is contained to the extent that the strength of the ink receiving layer is not impaired, other The binder can be contained in a larger amount as compared with a binder such as a vinyl chloride-vinyl acetate copolymer resin or a polyester resin, and as a result, the water resistance and density of the image and the blur prevention performance can be further improved. In addition, if it is an acrylic resin, it is possible to obtain an ink receiving layer having excellent light resistance as compared with other binders. Such an acrylic resin is not particularly limited as long as it has these characteristics. For example, Movinyl 718, Movinyl 763, Movinyl 760H, Movinyl 942, Movinyl 735 (all manufactured by Clariant Polymer Co., Ltd.) ), Peth Resin A1
What is marketed as 63G (made by Takamatsu Yushi Co., Ltd.) can be used.

A typical solvent in the water-based ink is a polyhydric alcohol or a derivative thereof, and examples thereof include the following. As the polyhydric alcohol, ethylene glycol, diethylene glycol, propylene glycol, 1,3-butylene glycol, 1,
4-butylene glycol, 1,5-pentanediol,
Neopentyl glycol, 1,6-hexanediol,
1,2-cyclohexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, glycerin, pentaerythritol and the like can be mentioned. Further, as the derivative of the polyhydric alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol isopropyl ether, ethylene glycol monobutyl ether, ethylene glycol isobutyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether. Ethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, cellosolve acetate, etc., or a solvent pocket book edited by the Society of Synthetic Organic Chemistry (September 20, 1990)
(Published by Ohmsha Co., Ltd.) on pages 479-574 and polyhydric alcohols and derivatives thereof.

Content of acrylic resin having the above characteristics in the ink receiving layer (solid content in the ink receiving layer)
Is preferably 20 to 50% by weight, particularly preferably 30 to 40% by weight. When the amount of the acrylic resin having the above-mentioned properties is less than this range, the strength of the ink receiving layer tends to be lowered, and conversely, when it is more than this range, the ink absorbency and the drying property tend to be insufficient. Further, in the ink receiving layer, one or more binders other than the acrylic resin having the above-mentioned properties can be mixed and used as long as the effects of the present invention are not impaired. As such a binder, for example, an acrylic resin other than the acrylic resin having the above properties, polyvinyl alcohol, polyvinyl butyral, gelatin, polyvinyl acetal, carboxymethyl cellulose, polyvinylpyrrolidone, polyester, urethane resin, chlorinated polypropylene and these Examples include a copolymer and the like. However, it is appropriate that the proportion of the binder other than the acrylic resin having the above-mentioned characteristics used be 30% by weight or less based on the entire binder.

The filler used in the ink receiving layer is not limited to organic or inorganic materials, and includes calcium carbonate, silica, talc, clay, diatomaceous earth, aluminum hydroxide, polystyrene, polymethacrylate, titanium oxide and calcined kaolin. Among them, silica is particularly preferable because it has a large pore volume, a large absorption amount, excellent ink acceptability, and high whiteness. These may be used alone,
You may use it in combination of 2 or more type. The content of the filler in the ink receiving layer is 50 to 75% by weight, especially 55 to 70% by weight.
Weight percent is preferred. When the amount of the filler is less than this range, the ink absorbency / drying property tends to be insufficient, and conversely, when the amount is more than this range, the strength of the ink receiving layer tends to decrease.

In the present invention, the layer formed by applying and drying the ink receiving layer forming material containing such a binder and filler is impregnated with an addition polymer of dimethylamine and epichlorohydrin. However, the pH of the layer before the impregnation treatment needs to be less than 6.5, preferably less than 6.0, and if the pH is 6.5 or more, a sufficient image density cannot be obtained. The pH can be adjusted, for example, by adding various acidic substances, preferably sulfuric acid, to the ink-receiving layer forming material. When an acrylic resin having a low pH is used as the acrylic resin having the above-mentioned characteristics, the addition of the acidic substance to be contained is added. This is the most preferable method because the amount can be reduced or no addition can be made at all. Among the above-mentioned acrylic resins, those commercially available as Movinyl 718, Movinyl 763, Movinyl 760H and Pethresin A163G fall under this category. To do. The pH of the layer mentioned here means a pH value measured according to JIS P8133. The method of impregnating the addition polymer of dimethylamine and epichlorohydrin into the layer formed by coating and drying the ink receiving layer forming material and having a pH of less than 6.5 is a solution containing this addition polymer. There is a method of immersing the layer in a layer, a method of applying a solution containing the addition polymer to the layer, a method of spraying the solution containing the addition polymer or the addition polymer itself to the layer, but the ease of operation From the viewpoint of the above, a method of applying a solution containing an addition polymer of dimethylamine and epichlorohydrin to a layer is preferable.
When coating, conventionally known methods such as reverse roll coating, air knife coating, gravure coating and blade coating can be used.

The addition polymer of dimethylamine and epichlorohydrin with which the layer is impregnated is preferably localized so as to increase in the upper part of the layer, which has a great influence on the water resistance of the image. It is possible to relatively reduce the amount of the addition polymer of dimethylamine and epichlorohydrin having the property of decreasing For that purpose, a solution containing an addition polymer of dimethylamine and epichlorohydrin is diluted with water or the like so that the addition polymer is 7 to 10% by weight, and a solution containing no binder. It is appropriate to do. Regarding the preferable content of the addition polymer of dimethylamine and epichlorohydrin in the ink receiving layer,
It is as follows. That is, the layer after the impregnation and drying, in other words, in the ink receiving layer including the addition polymer of dimethylamine and epichlorohydrin, the addition polymer of dimethylamine and epichlorohydrin has a solid content weight ratio. Is preferably 15% or less, more preferably 2 to 1
It is 0%, more preferably 3 to 7%. When the addition polymer of dimethylamine and epichlorohydrin is small, image bleeding tends to occur, and the water resistance of the image tends to decrease. Conversely, when it is too large, the water resistance of the image tends to decrease. .

In the ink receiving layer, if necessary, an antifoaming agent, an antistatic agent, an ultraviolet absorber, an optical brightening agent, an antiseptic, a pigment dispersant, and Various additives such as a sticky agent can be contained, and the composition is coated by being contained in the ink receiving layer forming material. The thickness of the ink receiving layer is preferably 30 to 70 μm, particularly preferably 40 to 60 μm. If the thickness is less than this range, the ink absorbency / drying property tends to decrease, while if it is greater than this range, the strength and water resistance of the layer tend to decrease.

The ink jet recording sheet of the present invention may have at least one ink receiving layer of the present invention, and various layers can be provided as long as the object of the present invention is not impaired. For example, in order to improve the adhesion between the base material and the ink receiving layer, between the ink receiving layer and the base material,
An anchor coat layer may be provided, or a hiding layer having high opacity may be provided in order to improve the hiding property or to provide the hiding property regardless of the substrate. Furthermore, the ink receiving layer may be provided not only on one side of the base material but also on both sides of the base material depending on the application. The ink-receiving layer can be formed by applying a coating liquid in which the constituent components are dissolved or dispersed in a suitable solvent by a known method such as reverse roll coating, air knife coating, gravure coating, or blade coating. .

[0019]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The performance of the inkjet recording sheet was evaluated according to the following procedure. The printing was performed with an inkjet printer (model name: DJ2000CP) manufactured by Hewlett-Packard Company using genuine water-based ink using a pigment as a coloring material. (1) Water resistance of coating layer (ink receiving layer) (rubbing resistance in a wet state) With a sufficiently wet cotton swab, the surface of the ink receiving layer of the ink jet recording sheet is treated with ink so that the load is 100 g. It was rubbed until the receiving layer detached, and the number of times required for it was counted. In addition, one round trip (one way 50 mm) was counted as once. The maximum number is 100 times, and when the ink receiving layer is not detached after 100 times, it is displayed as 100 times.

(2) Water resistance of image (dripping) Cyan, magenta, yellow and mixed colors (cyan, magenta, yellow) are solid-printed in a single color, and 5 minutes after the printing, one drop of distilled water is dropped on the printing part to drop distilled water. The degree of ink outflow when the ink was completely absorbed was visually observed and evaluated according to the following criteria. ◯: Some outflow occurred, but there was no problem in practical use Δ: Outflow occurred, there was a problem in practical use ×: Many outflow occurred, there was a problem in practical use (3) Image density cyan, magenta, yellow and mixed colors (cyan , Magenta, and yellow) were solidly printed, and the reflection density of the image was measured with a Macbeth densitometer RD-918.

Example 1 As a substrate, a white foamed polypropylene film having a thickness of 80 μm (micro void film manufactured by YUPO Corporation, trade name: YUPO FPG # 80) was used.
A uniform mixture of the following components was used as an anchor coating liquid. (a) Acrylic resin [BASF Dispersion Co., Ltd.
Made, product name: Acronal YJ-6221D, solid content concentration 49% by weight, anionic] 60 parts by weight (b) Calcium carbonate [made by Shiraishi Central Research Institute, product name: Callite SA, solid content concentration 100% by weight Aragonite] 10 parts by weight As a coating liquid for forming an ink receiving layer, a uniform mixture of the following components was used. (1) Silica [manufactured by Fuji Silysia Chemical Ltd., trade name: Sylysia 440, solid content concentration 100% by weight, particle diameter (Coulter counter method) 3.5 μm, pore volume 1.25 m
1 / g] 17.55 parts by weight (2) Acrylic resin [manufactured by Clariant Polymer Co., Ltd., trade name: Movinyl 718, solid content concentration 45% by weight, poor solvent or nonsolvent to solvent in aqueous ink , Hydrophobic, anionic, pH 4 to 6] 21.66 parts by weight (3) Antifoaming agent [manufactured by San Nopco Ltd., trade name: SN deformer 480, solid content concentration 100% by weight] 0.20 parts by weight (4) 60.59 parts by weight of water Apply the anchor coating solution on the base material to give a thickness of 3
An anchor coat layer having a thickness of 55 μm (after drying) is formed, and a coating liquid for forming an ink receiving layer is applied on the anchor coat layer to a thickness of 55 μm.
A layer (after drying) was formed. After the layer has dried, the p
When H was measured, it was 5.5. To the layer after drying, an addition polymerization product of dimethylamine and epichlorohydrin [manufactured by Nika Kagaku Co., Ltd., trade name: Neofix RE, solid content concentration 40% by weight] was diluted with water to obtain a solid content concentration. 7.
A 5% aqueous solution was applied and impregnated to prepare an inkjet recording sheet. The amount of the aqueous solution is 5 in terms of solid content weight ratio with respect to the ink receiving layer (including the addition polymer of dimethylamine and epichlorohydrin) after being impregnated with the addition polymer of dimethylamine and epichlorohydrin. Adjusted to be%.

Example 2 The acrylic resin in the coating liquid for forming the ink receiving layer was changed to acrylic resin [made by Clariant Polymer Co., Ltd., trade name: Movinyl 763, solid content concentration 48% by weight, relative to solvent in aqueous ink]. An ink jet recording sheet was produced in the same manner as in Example 1 except that the amount was changed to 20.31 parts by weight of poor solvent or non-solvent, hydrophobicity, anionicity, pH 4.5 to 6.5]. The pH of the layer before impregnation with the addition polymer of dimethylamine and epichlorohydrin was 6.4.
Met.

Example 3 The acrylic resin in the coating liquid for forming the ink receiving layer was changed from acrylic resin [Clariant Polymer Co., Ltd., trade name: Movinyl 760H, solid content concentration 50% by weight, to solvent in aqueous ink]. Poor solvent or non-solvent, hydrophobic, anionic, pH 5 to 7] 19.49 parts by weight,
An ink jet recording sheet was produced in the same manner as in Example 1. The pH of the layer before being impregnated with the addition polymer of dimethylamine and epichlorohydrin was 5.9.

Example 4 The acrylic resin in the coating liquid for forming the ink receiving layer was changed to acrylic resin [Takamatsu Yushi Co., Ltd., trade name: PES Resin A16.
3G, solid content concentration 28% by weight, poor solvent or nonsolvent to solvent in aqueous ink, hydrophobic, anionic, pH
5-6] An inkjet recording sheet was produced in the same manner as in Example 1 except that the amount was changed to 34.81 parts by weight.
The pH of the layer before being impregnated with the addition polymer of dimethylamine and epichlorohydrin was 5.9.

Comparative Example 1 The acrylic resin in the coating liquid for forming the ink receiving layer was the same weight as the acrylic resin [made by Clariant Polymer Co., Ltd., trade name: Movinyl 942, solid content concentration 45% by weight, in aqueous ink]. Antisolvent or nonsolvent to solvent, hydrophobic,
An ink jet recording sheet was prepared in the same manner as in Example 1 except that the anionic pH was changed to 7-9.
The pH of the layer before being impregnated with the addition polymer of dimethylamine and epichlorohydrin was 6.9.

Comparative Example 2 The acrylic resin in the coating liquid for forming the ink-receiving layer was replaced with acrylic resin [Clariant Polymer Co., Ltd., trade name: Movinyl 735, solid content concentration 43% by weight, relative to solvent in aqueous ink]. An ink jet recording sheet was produced in the same manner as in Example 1, except that the amount was changed to 22.67 parts by weight, which is poor solvent or non-solvent, hydrophobic, anionic, pH 7-9. The pH of the layer before impregnation with the addition polymer of dimethylamine and epichlorohydrin was 6.8.

Comparative Example 3 The procedure of Example 1 was repeated, except that the coating liquid for forming the ink-receiving layer was only applied and dried, and the addition polymer of dimethylamine and epichlorohydrin was not impregnated. An inkjet recording sheet was prepared.

For each of the ink jet recording sheets obtained in Examples 1 to 4 and Comparative Examples 1 to 3, the water resistance of the coating layer (rubbing resistance in a wet state) and the water resistance of the image (dripping) The image density was evaluated, and the results are shown in Table 1. In addition, in each of Examples 1 to 4 and Comparative Examples 1 and 2, the addition polymer of dimethylamine and epichlorohydrin permeated the layer, and a new layer was not formed on the substrate.

[0029]

[Table 1]

[0030]

The ink jet recording sheet of the present invention has the basic characteristics of the conventional ink jet recording sheet, but is particularly excellent in the water resistance of the image, the water resistance of the ink receiving layer and the image density. Is. Since the water-based ink usually contains water as a solvent and a polyhydric alcohol or a derivative thereof, the inkjet recording sheet of the present invention is suitable for printing with a water-based ink. Some of the aqueous inks use a dye as a coloring material and some use a pigment, and the ink jet recording sheet of the present invention is particularly effective for those using a pigment.

Claims (3)

[Claims] 1. An ink-accepting layer is provided on a substrate, and the ink-accepting layer is a hydrophobic, anionic acrylic resin exhibiting a poor solvent property or a non-solvent property with respect to the solvent in the aqueous ink. A layer having a pH of less than 6.5 formed by applying and drying an ink receiving layer forming material as a binder,
An inkjet recording sheet comprising a layer impregnated with an addition polymer of dimethylamine and epichlorohydrin. 2. The ink receiving layer according to claim 1, wherein the ink receiving layer is impregnated with the addition polymer of dimethylamine and epichlorohydrin by applying a solution containing the addition polymer of dimethylamine and epichlorohydrin. Inkjet recording sheet. 3. The ink jet recording sheet according to claim 1, wherein the solvent in the aqueous ink is a polyhydric alcohol or a derivative thereof.