JP2008143152A - Ink-jet recording sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink-jet recording sheet excellent in printing concentration and, in addition, excellent in water resistance of printed letters when printing in full color on the ink-jet printing sheet. <P>SOLUTION: The ink-jet recording sheet keeps an ink acceptor layer overlaying at least one face of a support, wherein the ink acceptor layer including a diallylamine/acrylamide copolymer having an average molecular weight of 400,000-2,000,000 and not greater than 10 mass% of molecules having a molecular weight of not greater than 100,000, and a cationic compound having a primary amino group. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to an inkjet recording sheet used for inkjet printing.

Inkjet recording is a method in which liquid ink is ejected from fine nozzles and adhered to a recording medium such as paper to form an image, but there is little noise during recording, and color recording is easy. It is widely used for terminal printers, facsimiles, plotters, form printing devices, and the like because it enables high-speed recording and is cheaper than other recording-type printing devices.

Due to the rapid spread of recent printers, high-definition and high-speed printing, and the advent of digital cameras, high-level characteristics are required for recording media used in this inkjet recording system, that is, inkjet recording sheets. became. Specifically, it is an ink jet recording sheet having high printing density, high water resistance of printing, high image quality and storability.

In order to meet such demands, many proposals have been made regarding an ink jet recording sheet in which an ink receiving layer mainly composed of a pigment and an adhesive is provided on a support.

Furthermore, a water-proofing agent is often used for the purpose of imparting water resistance to printing. For example, cationic polymers such as dicyandiamine condensate, polyamine, and polyethyleneimine have been proposed as water-proofing agents, but these cationic polymers satisfy both printing quality and printing water resistance. Is not done.

Further, diallylamine / acrylamide copolymer is used as one of the cationic polymers. (For example, refer to Patent Document 1) In this context, the molecular weight distribution is referred to in the text as "the weight average molecular weight of the cationic resin used in the present invention is not particularly limited, but preferably 1,000 to 200,000, more preferably. 5,000 to 200,000 is desirable ".

  Also in Patent Document 2, although diallylamine / acrylamide copolymer is described, it is not described in the claim as well, and it is only suggested that a weight average molecular weight of 100,000 or less is preferable in the text. .

Patent Document 3 is a document in which the molecular weight distribution of a diallylamine / acrylamide copolymer is mentioned. In this case, the cationic polymer having a weight average molecular weight of 100,000 or more is 50 to 90% by mass, and that having a weight average molecular weight of 10,000 to 50,000 is 10 to 50% by mass.

An inkjet recording sheet containing a cationic compound having a primary amino group has also been proposed. (For example, see Patent Document 4)
However, there is no particular mention about the combination with other cationic polymers, and the printing water resistance is insufficient as it is.

JP 2004-001332 A JP 2003-165268 A JP 2003-145916 A JP 2003-305942 A

The full-color inkjet recording image formed using these conventional inkjet recording sheets has a problem that the water resistance of printing is insufficient and the printing density is insufficient. An object of the present invention is to provide an ink jet recording sheet that can provide a high print density and high water resistance when printed in full color on an ink jet recording sheet.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that this can be achieved by employing the following configuration, and have reached the present invention.
(1) An inkjet recording sheet having an ink receiving layer provided on at least one surface of a support, wherein the ink receiving layer contains a diallylamine / acrylamide copolymer having a weight average molecular weight of 400,000 to 2,000,000. An inkjet recording sheet.
(2) The inkjet recording sheet according to (1), wherein the molecular weight distribution of the diallylamine / acrylamide copolymer is 10% by mass or less with a molecular weight of 100,000 or less.
(3) The ink jet recording sheet according to (1) or (2), wherein the ink receiving layer further contains 0.5 to 5% by mass of a cationic compound having a primary amino group.
(4) The inkjet recording sheet according to any one of (1) to (3), wherein the support is a water-resistant support.

The inkjet recording sheet of the present invention has a high printing density, high printing water resistance, and high water resistance.

The ink jet recording sheet of the present invention basically comprises a support and an ink receiving layer provided on at least one surface of the support. The ink receiving layer is made of an adhesive, a pigment, a cationic polymer compound, and the like.

The adhesive used for the ink receiving layer is not particularly limited. For example, water-insoluble materials such as polyvinyl alcohol and / or derivatives thereof, proteins such as polyvinyl pyrrolidone and casein, starch and / or derivatives thereof, styrene-butadiene copolymers, polymers or copolymers of acrylate esters and methacrylate esters Acrylic polymer latex, vinyl polymer latex such as ethylene-vinyl acetate copolymer, ethylene-vinyl chloride copolymer, etc., or functional group-containing modified weights such as carboxyl groups and cationic groups of these various polymers Synthetic resin-based aqueous adhesives such as united latex, melamine resin, urea resin, maleic anhydride copolymer resin, polyacrylamide resin, polymethyl methacrylate resin, polyurethane resin, unsaturated polyester resin, polyvinyl butyral, Alkyd resin, etc. One or more monomers selected from among polymer compounds such as a synthetic resin based adhesive can be used.

Among these adhesives, it is used for the purpose of improving liquid absorbency because inclusion of polyvinyl alcohol or polyvinyl alcohol derivatives has good adhesion to pigments or supports and good affinity with water-based inks. It is done. In particular, it is preferable to use polyvinyl alcohol or a derivative of polyvinyl alcohol in combination.

In the present invention, a diallylamine / acrylamide copolymer is included in the ink receiving layer for the purpose of improving the water resistance of a printed image with a water-based ink, and its weight average molecular weight is 400,000 to 2,000,000. If the weight average molecular weight is less than 400,000, the effect of improving water resistance is insufficient, and if it exceeds 2 million, production may be difficult and the cost may increase.
Further, the diallylamine / acrylamide copolymer having a molecular weight of 100,000 or less is preferably 10% by mass or less. If it exceeds 10% by mass, the effect of improving water resistance may be insufficient.

In the present invention, it is preferable to use 0.5 to 5% by mass of a cationic compound having a primary amino group. Examples of the cationic compound having a primary amino group include polyallylamine, polyvinylamine, polyethyleneimine, and derivatives thereof. Of these, polyallylamine and its derivatives are preferably used. When the content of the cationic compound having a primary amino group is less than 0.5% by mass, the synergistic effect for improving the water resistance by using together with the diallylamine / acrylamide copolymer is low, and when the content exceeds 5% by mass. In some cases, yellowing of white paper may occur under high temperature and high humidity.

Further, another cationic compound can be used in combination in the ink receiving layer. For example,
1) Polyalkylene polyamines such as polyethylene polyamine and polypropylene polyamine or derivatives thereof,
2) an acrylic polymer having a secondary amino group, a tertiary amino group or a quaternary ammonium group,
3) polyvinylamidines,
4) Dicyan-based cationic polymer compound represented by dicyandiamide / formalin copolymer,
5) Polyamine cationic polymer compound represented by dicyandiamide / polyethyleneamine copolymer,
6) Epichlorohydrin / dimethylamine copolymer,
7) diallyldimethylammonium-SO ₂ polycondensate,
8) diallylamine salt / SO ₂ polycondensate,
9) diallyldimethylammonium chloride polymer,
10) diallyldimethylammonium chloride-acrylamide copolymer,
11) Dialkylaminoethyl (meth) acrylate quaternary salt copolymer,
12) Acrylamide-diallylamine copolymer,
13) Cationic polymer compounds such as cationic resins having a 5-membered ring amidine structure.

As the pigment used in the ink receiving layer, a pigment that is porous, has high ink absorbability, and enables clear color development is preferable. Such pigments include fine particle synthetic silica, zeolite, calcium carbonate, calcium silicate, aluminum hydroxide, alumina, calcined clay, kaolin, clay, talc, white carbon, organic pigments (plastic pigments), and generally paper. Although the well-known pigment used for coating is mentioned, especially a fine particle synthetic silica is preferable. The average particle diameter of the fine particle synthetic silica is more preferably 2 to 20 μm.

In addition to surfactants and hardeners, the ink-receiving layer further includes coloring dyes, coloring pigments, ink dye fixing agents, UV absorbers, antioxidants, pigment dispersants, foam suppressors, foaming agents, Add various known additives such as antifoaming agents, leveling agents, preservatives, optical brighteners, viscosity stabilizers, mold release agents, penetrating agents, wetting agents, thermal gelling agents, lubricants, and pH adjusting agents. You can also.

The thickness of the ink receiving layer used in the present invention is preferably 2 to 90 μm, more preferably 10 to 70 μm.

Examples of the support used in the present invention include a non-water resistant support and a water resistant support, and a water resistant support is preferred. Thereby, water resistance strength can be made high.

Examples of the non-water resistant support include known acidic paper and neutral paper used for coated paper.

Examples of the water resistant support include a resin film, a nonwoven fabric, and a resin-coated paper. As the resin film, polyester resins and olefin resins which are thermoplastic resins are preferable. Examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polycyclohexene terephthalate, and polyethylene naphthalate. Moreover, as an olefin resin, what consists of polyethylene, a polypropylene, an ethylene propylene copolymer, an ethylene vinyl acetate copolymer, or what has these as a main component is mentioned. The resin film is preferably constituted by appropriately selecting one or more of these resins. Further, these resins may be used by mixing other thermoplastic resins such as polystyrene and acrylate copolymer.

Other resin films include diacetate resins, triacetate resins, acrylic resins, polycarbonate resins, polyvinyl chloride, polyimide resins, cellophane, celluloid, and the like.

The resin film can be formed by stretching these resins in a uniaxial direction or a biaxial direction. In this case, an inorganic fine powder may be mixed in the resin.

Alternatively, these resins may be uniaxially stretched or biaxially stretched to form a paper-like layer, and one or more layers may be laminated on a base material layer such as paper to form a support. In this case, the resin film can be laminated on one side or both sides of the base material layer to form a support having 2 to 3 layers. Moreover, a resin film as a surface layer can be further laminated thereon to form a support of 3 to 5 layers. A plurality of resin films can be laminated to form a support. Thus, what laminated | stacked the paper-like resin film is generally called the synthetic paper.

As the nonwoven fabric, a nonwoven fabric such as polyolefin, polyester, or polystyrene can be used.
Examples of the resin-coated paper include paper obtained by extruding and laminating a thermoplastic resin on a paper support,
Examples of the thermoplastic resin include polyolefin resins such as polypropylene and polyethylene, and polyester resins. In the thermoplastic resin, a white pigment such as titanium dioxide, a dye, an ultraviolet absorber, and the like can be appropriately blended.

The support may be adjusted in color with a fluorescent dye, fluorescent pigment or the like, may be provided with an antistatic layer, an anchor layer, a barrier layer, or may be subjected to corona treatment.

These supports may be transparent or opaque. The thickness of the support is preferably 400 μm or less, and more preferably 40 to 250 μm.

In the present invention, an ink receiving layer is provided on at least one surface of a support, but an ink absorbing layer, an ink fixing layer, an intermediate layer, a protective layer, and the like may be further provided.

The method for coating the ink receiving layer on the support is not particularly limited, and a known coating method can be used. For example, size press method, gate roll method, shim sizer method, slide bead method, curtain method, extrusion method, air knife method, roll coating method, rod blade coating method, blade coating method, bar coating method, die coating method, lip coating The method etc. are mentioned.

  Hereinafter, the present invention will be described in more detail by way of examples. In the following examples, parts and% represent parts by mass and% by mass unless otherwise specified.

[Example 1]
As the support, paper (trade name: OK coat, manufactured by Oji Paper Co., Ltd., 127.9 g / m ² ) was used. On one side of this support, coating A having the following composition is applied by a bar coating method, dried at 120 to 130 ° C. for 2 to 3 minutes, and the thickness of the ink receiving layer after drying is 35 μm. A sheet was produced.

<Paint A>
Amorphous silica (trade name: Mizukasil P-78F, manufactured by Mizusawa Chemical Co., Ltd.) 100 parts Cationic polymer compound: diallylamine / acrylamide copolymer (weight-average molecular weight 600,000, ratio of molecular weight 100,000 or less 12%) (Product name: HP-780A, manufactured by Senka) 20 parts Adhesive: PVA graft acrylic copolymer emulsion (Product name: PA-82, manufactured by Daicel Chemical Industries) 30 parts Partially saponified polyvinyl alcohol (Product name: PVA420, 30 parts made by Kuraray)

[Example 2]
An inkjet recording sheet was prepared in the same manner as in Example 1 except that synthetic paper (trade name: YUPO FPG-110, manufactured by YUPO Corporation, thickness: 110 μm) was used as the support.

[Example 3]
An ink jet recording sheet was prepared in the same manner as in Example 1 except that paint B having the following composition was used in place of paint A.

<Paint B>
Amorphous silica (trade name: Mizukasil P-78F, manufactured by Mizusawa Chemical Co., Ltd.) 100 parts Cationic polymer compound: diallylamine / acrylamide copolymer (weight average molecular weight 600,000, ratio of molecular weight 100,000 or less 7%) (Product name: OG-0851N, manufactured by OG) 20 parts Adhesive: PVA graft acrylic copolymer emulsion (Product name: PA-82, manufactured by Daicel Chemical Industries) 30 parts, partially saponified polyvinyl alcohol (Product name: PVA420, Kuraray) 30 parts

[Example 4]
An inkjet recording sheet was prepared in the same manner as in Example 3 except that synthetic paper (trade name: YUPO FPG-110, manufactured by YUPO Corporation, thickness: 110 μm) was used as the support.

[Example 5]
An ink jet recording sheet was produced in the same manner as in Example 2 except that paint C having the following composition was used instead of paint A.

<Paint C>
Amorphous silica (trade name: Mizukasil P-78F, manufactured by Mizusawa Chemical Co., Ltd.) 100 parts Cationic polymer compound: diallylamine / acrylamide copolymer (weight average molecular weight 600,000, ratio of molecular weight 100,000 or less 7%) (Product name: OG-0851N, manufactured by OG) 5 parts

・ Cationic polymer compound: diallyldimethylammonium hydrochloride (weight average molecular weight 20,000) (trade name: Unisense CP-91, manufactured by Senka) 15 parts ・ Adhesive: PVA graft acrylic copolymer emulsion (trade name: PA- 82, Daicel Chemical Industries) 30 parts, partially saponified polyvinyl alcohol (trade name: PVA420, Kuraray) 30 parts

[Example 6]
An ink jet recording sheet was prepared in the same manner as in Example 2, except that 4 parts of a polyallylamine derivative having a primary amino group (trade name: Pulset JK-501, manufactured by Meisei Chemical Industry) was added to Paint A. did.

[Comparative Example 1]
An ink jet recording sheet was produced in the same manner as in Example 1 except that paint D having the following composition was used in place of paint A.
<Paint D>
Amorphous silica (trade name: Mizukasil P-78F, manufactured by Mizusawa Chemical Co., Ltd.) 100 parts Cationic polymer compound: diallylamine / acrylamide copolymer (weight average molecular weight 300,000) (trade name: HP-752A, SENKA 20 parts) Adhesive: 30 parts PVA graft acrylic copolymer emulsion (trade name: PA-82, manufactured by Daicel Chemical Industries) 30 parts partially saponified polyvinyl alcohol (trade name: PVA420, manufactured by Kuraray)

[Comparative Example 2]
An inkjet recording sheet was prepared in the same manner as in Comparative Example 1 except that synthetic paper (trade name: YUPO FPG-110, manufactured by YUPO Corporation, thickness 110 μm) was used as the support.

[Comparative Example 3]
An ink jet recording sheet was prepared in the same manner as in Example 2 except that paint E having the following composition was used in place of paint A.

<Paint E>
Amorphous silica (trade name: Mizukasil P-78F, manufactured by Mizusawa Chemical Co., Ltd.) 100 parts Cationic polymer compound: diallylamine / acrylamide copolymer (weight average molecular weight 80,000) (trade name: SR-1001, Residential 20 parts / adhesive: PVA graft acrylic copolymer emulsion (trade name: PA-82, manufactured by Daicel Chemical Industries) 30 parts / partial saponified polyvinyl alcohol (trade name: PVA420, manufactured by Kuraray)

[Comparative Example 4]
An ink jet recording sheet was produced in the same manner as in Example 2 except that paint F having the following composition was used in place of paint A.

<Paint F>
・ Amorphous silica (trade name: Mizukasil P-78F, manufactured by Mizusawa Chemical Industry Co., Ltd.) ・ Cationic polymer compound: diallyldimethylammonium hydrochloride (weight average molecular weight 700,000) (trade name: HP-46A, manufactured by Senka) ) 20 parts-Adhesive: 30 parts of PVA graft acrylic copolymer emulsion (trade name: PA-82, manufactured by Daicel Chemical Industries)-30 parts of partially saponified polyvinyl alcohol (trade name: PVA420, manufactured by Kuraray)

[Comparative Example 5]
An ink jet recording sheet was prepared in the same manner as in Example 2 except that paint G having the following composition was used in place of paint A.
<Paint G>
・ Amorphous silica (trade name: Mizukasil P-78F, manufactured by Mizusawa Chemical Co., Ltd.) ・ Cationic polymer compound: diallyldimethylammonium hydrochloride (weight average molecular weight 20,000) (trade name: CP-91, manufactured by Senka) ) 20 parts-Adhesive: 30 parts of PVA graft acrylic copolymer emulsion (trade name: PA-82, manufactured by Daicel Chemical Industries)-30 parts of partially saponified polyvinyl alcohol (trade name: PVA420, manufactured by Kuraray)

For the ink jet recording sheets obtained in the above examples and comparative examples, the printing density and water resistance were evaluated by the following methods. The results are shown in Table 1.
[Evaluation method of print density]
Using an inkjet plotter (trade name: Designjet 2500CP, manufactured by Hewlett Packard), using UV ink (pigment ink, manufactured by Hewlett Packard) or imaging ink (dye ink, manufactured by Hewlett Packard), 100% yellow, 100% magenta, Printing was performed at a ratio of 100% cyan and 100% black.

The print density was evaluated by visually observing the density of the print sample with UV ink and the print sample with imaging ink on the inkjet recording sheet, and evaluated according to the following criteria.
A Excellent B Normal C Inferior B or higher is a level that can withstand practical use.

[Method for evaluating water resistance of printed parts]
The print sample prepared in the above [Method for evaluating print density] was immersed in water for 10 minutes, and then bleeding of the print portion of the print sample was visually observed and evaluated according to the following criteria.
5 Excellent 4 Excellent 3 Normal 2 Slightly inferior 1 Inferior 3 or higher is the level that can withstand practical use.

[Evaluation method of water resistance of ink jet recording sheet]
The ink jet ink jet recording sheet having the ink receiving layer coating material formed on the support was immersed in water for 10 minutes and then torn by hand, and the strength was evaluated according to the following criteria.
○ The best △ Normal × The worst △ or more is the level that can withstand practical use.

The evaluation results are shown in the table.

As is apparent from Table 1, the ink jet recording sheet of the present invention is an ink jet recording sheet excellent in printing density, printing portion water resistance, and water resistance of the recording sheet.

INDUSTRIAL APPLICABILITY The present invention is an ink jet recording sheet having a high printing density, water resistance at a printing portion and high water resistance of the sheet, and is extremely useful in practice.

Claims (4)

An ink jet recording sheet having an ink receiving layer provided on at least one surface of a support, wherein the ink receiving layer contains a diallylamine / acrylamide copolymer having a weight average molecular weight of 400,000 to 2,000,000. Recording sheet. 2. The ink jet recording sheet according to claim 1, wherein in the molecular weight distribution of the diallylamine / acrylamide copolymer, the one having a molecular weight of 100,000 or less is 10 mass% or less. The ink jet recording sheet according to claim 1 or 2, wherein the ink receiving layer further contains 0.5 to 5% by mass of a cationic compound having a primary amino group. The inkjet recording sheet according to claim 1, wherein the support is a water-resistant support.