JPH09109546A - Sheet for recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet for recording with excellent absorbing properties and drying properties of an ink on an ink receiving layer, good image clarity, excellent storing properties after recording and excellent water resistance of an image and further improve adhesive properties between a base sheet and the ink receiving layer of the sheet. SOLUTION: In a sheet for recording provided with an ink receiving layer 3 on at least one face of a base sheet 2, the ink receiving layer 3 comprises a hydrophilic resin and a water-soluble resin, and the hydrophilic resin is a copolymer consisting of a hydrophilic monomer, a hydrophobic monomer and a cationic monomer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording sheet excellent in image sharpness and storability without peeling of the ink receiving layer or protrusion of the ink receiving layer during ink absorption. .

[0002]

2. Description of the Related Art Conventionally, as an output print of a computer or a word processor, a wire dot recording system,
Various systems such as a thermosensitive coloring recording system, a thermosensitive transfer recording system, a thermosensitive sublimation transfer recording system, an electrophotographic recording system, and an ink jet recording system have been developed. Among them, the ink jet recording method is characterized in that plain paper can be used as a recording sheet, the printing cost is low, the apparatus is compact and there is no noise, and high speed recording is possible. For this reason, attention has been paid to the use as a printer for quickly and accurately outputting image information such as characters and figures produced by a computer or the like. Also,
Since it is easy to colorize and the picture is clear, there is also a request to record image information produced by a computer on a transparent recording sheet with an inkjet printer and use it as a manuscript such as OHP at conferences and various academic conference presentations. It is rising.

In general, an ink jet printer ejects recording ink from a nozzle by pressure of a fine piezoelectric element (piezo element) or air pressure (bubble jet) generated by heating a thermal head, and adheres to a recording sheet. The recording is performed by causing the recording. For this reason, as a recording ink used for ink jet recording, an ink that is difficult to dry is used in order to prevent ink ejection failure from nozzles due to an increase in viscosity due to drying of the ink. Usually, this ink component is a dye, resin, additive, etc. dissolved in water and alcohol. Therefore, a recording sheet on which recording is performed by an inkjet printer is required to absorb the liquid component of the attached ink and dry and solidify the ink. For this reason, a recording sheet in which an ink receiving layer is formed on a base sheet to enhance ink absorption is used.

In particular, the ink receiving layer of a recording sheet for an ink jet printer is required to have the following characteristics. Drying property: Excellent ink absorbency and fast ink drying property. Image clarity: An appropriate dot spread is obtained, and a clear image without blur is obtained. Preservability: No bleeding, fading, etc. of the recorded image after storage. Water resistance: The image does not blur or run out even if moisture adheres. Adhesion: The ink receiving layer does not easily peel off. Curling resistance: Curling does not occur in the recording sheet including the ink receiving layer in the use environment. From such a point of view, conventional recording sheets have an ink receiving layer on a base sheet, and as the receiving layer, one using a water-soluble resin, one using a hydrophilic resin, etc. have been devised. .

[0005]

However, an ink receiving layer formed by coating a water-soluble resin such as polyvinyl alcohol or polyvinyl pyrrolidone has high hydrophilicity and good image sharpness, but the resin is water-soluble. Therefore, there is a problem that the ink exhibits tackiness after absorbing the ink and sufficient drying property cannot be obtained. Further, since it is water-soluble, there is a problem that if a water drop is dropped on an image after recording, the image is easily dissolved. Further, the ink receiving layer formed by applying a hydrophilic resin which is appropriately hydrophobized such as polyvinyl acetal is water-insoluble and has appropriate water resistance, and thus has good drying property and water resistance. However, since it has high hydrophobicity, it has problems such as occurrence of solid unevenness and image bleeding. Further, these resins have a problem that they have poor adhesiveness with a plastic substrate and are easily peeled off by a cellophane tape or the like.

The present invention was devised in view of the above circumstances, and has excellent absorption and drying properties of ink in the ink receiving layer, good image clarity, and storage after recording. It is an object of the present invention to provide a recording sheet having excellent properties, excellent water resistance of an image, and strong adhesion between a base sheet and an ink receiving layer.

[0007]

In order to achieve the above object, the present invention provides a recording sheet in which an ink receiving layer is provided on at least one side of a substrate sheet, in which the ink receiving layer is hydrophilic and water-soluble. It is characterized in that it is made of a resin and the hydrophilic resin is a copolymer made of a hydrophilic monomer, a hydrophobic monomer and a cationic monomer. The hydrophilic resin of the ink receiving layer is an aqueous acrylic copolymer resin. As a hydrophilic resin for the ink receiving layer,
The aqueous acrylic copolymer resin is a copolymer of (meth) acrylic acid, (meth) acrylic acid ester, and (meth) acrylic acid ester quaternary ammonium salt. Further, the substrate sheet is characterized by being a thermoplastic.

The operation of the present invention is as follows. In a recording sheet in which an ink receiving layer is provided on at least one side of a base material sheet, the ink receiving layer comprises a hydrophilic resin and a water-soluble resin, and the hydrophilic resin is a hydrophilic monomer, a hydrophobic monomer or a cationic monomer. Since it is a copolymer composed of monomers, the ink receiving layer becomes water-insoluble after coating and drying, and the wet strength of the coating film after absorbing water for printing is increased and the drying property is improved. Further, the hydrophilic resin of the ink receiving layer suppresses stickiness after printing, and the water-soluble resin compensates for water absorption of the ink, so that excellent image clarity is obtained. In addition, since the hydrophilic resin of the ink receiving layer has both anionic and cationic ions, the fixability of the ink is good, and the image does not bleed during storage after printing. Furthermore, since the ink receiving layer contains a hydrophilic resin that becomes water-insoluble after coating and drying, it has excellent water resistance, and the ink receiving layer is a mixture of acrylic acid-containing resin and water-soluble resin as the hydrophilic resin. In that case, the adhesiveness with the plastic base material becomes strong.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing one embodiment of the recording sheet of the present invention. In FIG. 1, a recording sheet 1 is a base sheet 2
And an ink receiving layer 3 formed on one surface of the base sheet 2.

(Base Sheet) As the base sheet 2 used in the recording sheet of the present invention, the same base sheet as used in conventional recording sheets can be used as it is, and other base sheets can be used. Those can also be used and are not particularly limited. Synthetic paper such as polystyrene, fine paper, art paper, coated paper, cast coated paper, wallpaper,
Backing paper, synthetic resin impregnated paper, emulsion resin impregnated paper,
Examples include various colored or white papers such as synthetic rubber latex-impregnated papers, synthetic resin internal papers, paperboards, base materials for labels and plastic films. Further, a composite base material in which two or more of these materials are bonded together is also used. The thickness of these base material sheets is appropriately selected in consideration of strength and the like according to the application and is not particularly limited, but, for example, usually 5
It is about 0 to 200 μm.

The plastic film is preferably made of thermoplastic resin having heat resistance, dimensional stability and rigidity. For example, polyethylene terephthalate resin, polycarbonate resin, acrylic resin, polyvinyl chloride resin, polypropylene resin, polystyrene resin, polyvinyl alcohol resin, polyethylene resin,
The thickness of diacetate resin, triacetate resin, polyimide resin, etc. is about 5 to 250 μm, preferably 50 to 18 μm.
A film or plate having a thickness of about 0 μm may be used. In particular, when used for an overhead projector (OHP), a transparent substrate sheet is used even for these plastic films. Opaque plastic films and papers are used for applications that do not require transparency other than OHP applications. Further, one or both surfaces of the base sheet may be subjected to a corona discharge treatment or an easy adhesion treatment as necessary. Further, an anti-curl layer may be provided on the surface of the base sheet on which the ink receiving layer is not formed.

(Ink Receiving Layer) The ink receiving layer 3 is provided on one surface of the base sheet. The ink receiving layer 3 used in the present invention is characterized by comprising a hydrophilic resin and a water-soluble resin, and the hydrophilic resin is a copolymer comprising a hydrophilic monomer, a hydrophobic monomer and a cationic monomer. . The hydrophilic resin in the present invention is soluble in water or alcohol in a usual coating liquid, but the coating film after coating and drying is insoluble in water. Each monomer unit constituting the hydrophilic resin, for example, as a hydrophobic monomer unit, styrene, acrylic ester, vinyl acetate, vinyl chloride, vinyl acetal, urethane, ethylene, polyester, styrene-based, acrylic, Examples thereof include various vinyl-based, urethane-based, ethylene-based, polyester-based monomer units, or copolymerized units thereof.

The hydrophilic monomer units include acrylic acid, epoxy, maleic acid, vinylpyrrolidone, sulfonic acid, vinyl alcohol, amine, imine and the like, acrylic acid type, epoxy type, maleic acid type, sulfonic acid type,
Various vinyl-based, amine-based, or imine-based monomer units, or copolymerized units of these, or those grafted to the above-mentioned hydrophobic monomer units are used. Next, examples of the cationic monomer unit include quaternary ammonium salts of acrylic acid esters and quaternary ammonium salts of various monomers such as N, N-dimethyldiallylammonium chloride.

Further, as the acrylic monomer having a quaternary ammonium salt group, acrylic acid, methacrylic acid, or a functional group such as a carboxy group or a hydroxyl group such as a mono (meth) acrylate of these acids and glycol such as ethylene glycol. Reaction of glycidyltrimethylammonium chloride, 3-chloro-2-hydroxypropylpropyltrimethylammonium chloride, 3-chloro-2-hydroxylpropyltriethanolammonium chloride, glycidyldimethylbenzylammonium chloride, glycidyldimethylbutylammonium chloride, etc. with a monomer having a group Examples thereof include a monomer obtained by reacting a quaternary ammonium salt with a volatile compound.

The copolymerization ratio of the above-mentioned monomers is not particularly limited, but usually water or alcohol,
And mixtures thereof (alcohol is methanol, I
It must be soluble in water (PA, ethanol, propanol, etc.) and have water resistance after coating and drying, that is, it must be insoluble in water, and it is necessary to maintain sufficient water absorption and image sharpness. is there. As for the direction, if the amount of the hydrophobic monomer is too large, the water absorption and the image clarity are lowered, and if it is too small, the water resistance is lowered. On the other hand, when the amount of the hydrophilic monomer is too large, the water resistance is lowered and the water absorption is also lowered in some cases. If the amount of the hydrophilic monomer is too small, water absorption and image sharpness will decrease. If the amount of the cationic monomer is too large, the water resistance will be reduced, and if it is too small, the fixing property of the dye, the image clarity and the storage stability will be deteriorated.

The water-soluble resin used in the present invention is soluble in water or a mixed solvent of water and alcohol, and various conventionally known resins can be used. For example, polyvinyl alcohol, polyvinylpyrrolidone, poly (meth) acrylic acid, cellulosic resins (CMC, HEC, HPC, etc.),
At least water-soluble resin such as polyacrylamide, polyethylene oxide, polyethylene glycol, polyvinyl acetal resin, polyvinyl methyl ether, polyamine, polyethyleneimine, casein, gelatin, starch and / or their copolymers, cation / anion modified products, etc. One or more types are used.

As for the mixing ratio of the hydrophilic resin and the water-soluble resin, hydrophilic resin / water-soluble resin = 20/1 to 1/20 is used,
Particularly preferably, the range of 6/4 to 1/10 is suitable. In addition, from the point of importance of water resistance, 10/1
The range of 4/6 is preferable. If it deviates from this range, it becomes impossible to obtain a recording sheet having a well-balanced ink drying property, image clarity, adhesiveness and water resistance. Further, for the purpose of improving blocking resistance, coating strength, adhesion, dye fixability, etc., various polymers and additives in the above composition, for example, silica, colloidal silica, clay, calcium carbonate, titanium oxide, Fine particle fillers such as organic fine particles and alumina sol can be added. The particle size of the fine particle filler is preferably 0.1 to 60 μm, and it is preferable to add it in a ratio of 0.1 to 10% with respect to the total solid content. If it is less than 0.1%, a sufficient effect for preventing blocking cannot be obtained, and if it exceeds 10%, the transparency is deteriorated, which is not preferable for OHP applications. In addition, various surfactants, antioxidants, ultraviolet absorbers, antifoaming agents, various types of highly hydrophilic modified oils, and the like can be mixed and used as long as the effects of the present invention are not impaired.

As the method for coating the above-mentioned composition of the ink receiving layer on the substrate sheet, various conventionally known methods may be used, for example, gravure coat, gravure reverse coat, roll coat, wire bar coat,
Blade coat, knife coat, air knife coat,
Any method such as comma coating, slot die coating or dip coating may be used. If necessary, an additive is added to the resin constituting the ink receiving layer, and a solution prepared by dissolving or dispersing it in a suitable solvent is coated on the substrate sheet and dried to form the ink receiving layer. In addition, in order to secure the coating amount, the liquid having the same composition may be coated plural times. The thickness of the ink receiving layer when dried is 0.1 to 0.1
The thickness is 50 μm, preferably 3 to 30 μm. If the thickness is less than 0.1 μm, the ink absorption amount is not sufficient, while if it exceeds 10 μm, the manufacturing cost is high, which is not preferable.

The ink receiving layer described above is provided on the base sheet, but if the adhesion to the base sheet is weak, the ink receiving layer may be provided via the base sheet and the primer layer. . As the resin used for the primer layer,
For example, alkyd resin, polyester resin, polyvinyl acetate resin, vinyl chloride vinyl acetate copolymer resin, NBR resin, SBR
Resin, polyurethane resin, acrylic resin, polyamide and the like are used alone or as a mixture or modified product. The modified product is, for example, a product in which a hydroxyl group, a carboxylic acid, or a quaternary ammonium salt-containing monomer is copolymerized or grafted to improve the adhesiveness and hydrophilicity. Further, in order to improve the adhesiveness of the primer layer and the coating film strength, various curing agents such as epoxy resin, melamine resin,
It may be crosslinked with isocyanate or the like. As the method for forming the above-mentioned primer layer, the same method as the above-mentioned method for forming the ink receiving layer can be selected. The thickness of the primer layer, when dried, is 0.01 to 50 μm, preferably 0.1 to 10 μm.
m. If this thickness is less than 0.1 μm, the adhesiveness will not exhibit sufficient performance, while 10 μm
If it exceeds the range, the end face becomes sticky when the recording sheet is cut, which is not preferable in addition to the high manufacturing cost.

Further, an anti-curl layer, an antistatic layer or the like may be provided on the surface of the substrate sheet opposite to the surface on which the ink receiving layer is formed. As the anti-curl layer, it is possible to use the same water-soluble resin as the ink receiving layer, an acrylic resin, a polyester resin, or the like. In particular, when an acrylic resin, a modified acrylic resin, or a polyester resin is used, It is also useful in terms of imparting blocking property and slip property. The thickness of the anti-curl layer is 0.
The thickness is preferably about 1 to 50 μm, and the same method as the above-mentioned method for forming the ink receiving layer can be selected.

Further, an antistatic layer containing the following antistatic agent can be provided in order to prevent the recording sheet from being contaminated by dust and to stabilize the conveyance in the printer.
As the antistatic agent, conventionally known cations, anions,
Either zwitterionic or nonionic antistatic agents can be used. Examples thereof include cationic antistatic agents such as quaternary ammonium salts and polyamine derivatives, anionic antistatic agents such as alkyl phosphates, and nonionic antistatic agents such as fatty acid esters. The antistatic layer may be added with the above antistatic agent and a lubricant such as an organic or inorganic filler, and a compounded solution obtained by dissolving or dispersing them in a solvent by a known method, that is, gravure coating, gravure reverse coating. , Roll coating, etc.,
Dry and form. The thickness of the antistatic layer is about 0.001 to 0.1 μm when dried.

[0022]

(Composition of ink receiving layer)

 Hydrophilic resin: Cation-modified acrylic copolymer resin 3 parts (solid content) (Konishi Co., Ltd. Bondip P) Water-soluble resin: polyvinyl alcohol resin 7 parts (solid content) (Kuraray Co., Ltd. PVA 217)

(Example 2) A recording sheet was prepared in the same manner as in Example 1 except that the ink receiving layer had the following composition. [Composition of ink receiving layer] Hydrophilic resin: Cation-modified acrylic copolymer resin 5 parts (solid content) (Saftomer manufactured by Mitsubishi Chemical Corporation) Water-soluble resin: Polyvinyl alcohol resin 5 parts (solid content) (Kuraray Co., Ltd.) Made PVA 217)

Comparative Example 1 A recording sheet was prepared in the same manner as in Example 1 except that the ink receiving layer had the following composition. [Composition of ink receiving layer] Water-soluble resin: polyvinyl alcohol resin 5 parts (solid content) (PVA 217 manufactured by Kuraray Co., Ltd.)

Comparative Example 2 A recording sheet was prepared in the same manner as in Example 1 except that the ink receiving layer had the following composition. [Composition of ink receiving layer] Hydrophilic resin: cation-modified acrylic copolymer resin 5 parts (solid content) (Mitsubishi Chemical Corporation Saftomer)

Test patterns were printed on the recording sheets of the above Examples and Comparative Examples using an ink jet printer (BJC-600J manufactured by CANON), and the results shown in Table 1 below were obtained. In addition, the evaluation method of each performance shown in Table 1 is as follows.

(1) Dryability After printing the test pattern, a sensory test was conducted by lightly rubbing the printed surface of the recording sheet with a finger. ◯: Dry within 1 minute after printing. Δ: Dry within 3 minutes after printing X: Drying takes 3 minutes or more.

(2) Image sharpness After printing the test pattern, the solid image uniformity, dot reproducibility, and character bleeding state were visually confirmed and evaluated. -Solid uniformity ：: Uniform ink spread is obtained. Δ: The spread of the ink was slightly uneven and unevenness was observed. X: The spread of the ink is non-uniform, and a pool of ink is observed.・ Dot reproducibility ○: The outline of overlapping dots can be clearly observed. Δ: The outline of overlapping dots can be almost observed. X: The outline of the overlapping dots is unclear and difficult to observe.・ Bleeding of characters ○: No bleeding of characters is observed even when characters are printed on the solid print part. Δ: When a character is printed on the solid print portion, some character bleeding is observed. X: When characters are printed on the solid print portion, character bleeding is observed.

(3) Water resistance ◯: The ink receiving layer does not fall even after wiping with paper after dropping water (after 15 seconds). Δ: After dropping water (after 15 seconds), the ink receiving layer scarcely drops even if it is wiped off with paper. X: After dropping water (after 15 seconds), the ink receiving layer is easily dropped off by wiping with paper.

[0030]

[Table 1]

[0031]

The recording sheet of the present invention is provided with an ink receiving layer on at least one side of a substrate sheet, and the ink receiving layer comprises a hydrophilic resin and a water-soluble resin, and the hydrophilic resin is hydrophilic. Since it is a copolymer consisting of monomers, hydrophobic monomers, and cationic monomers, the drying property is improved,
Excellent image clarity is obtained, and water resistance is also excellent.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a recording sheet of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording sheet 2 Base sheet 3 Ink receiving layer

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[Procedure amendment]

[Submission date] March 5, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Name of invention

[Correction method] Change

[Correction contents]

Title of the invention Recording sheet

Claims (4)

[Claims] 1. A recording sheet in which an ink receiving layer is provided on at least one side of a substrate sheet, wherein the ink receiving layer comprises a hydrophilic resin and a water-soluble resin, and the hydrophilic resin is a hydrophilic monomer or a hydrophobic monomer. A recording sheet, which is a copolymer composed of a cationic monomer and a cationic monomer. 2. The method according to claim 1, wherein the hydrophilic resin of the ink receiving layer is an aqueous acrylic copolymer resin.
Recording sheet described in 1. 3. The hydrophilic resin of the ink receiving layer, the aqueous acrylic copolymer resin is (meth) acrylic acid, (meth)
Acrylic ester, (meth) acrylic ester 4th
The recording sheet according to claim 2, wherein the recording sheet is a copolymer of a primary ammonium salt. 4. The recording sheet according to any one of claims 1 to 3, wherein the base sheet is a thermoplastic.