JP3329531B2 - Inkjet recording sheet - Google Patents

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 for recording using ink, and more particularly to a method for suppressing curling toward the ink receiving layer side after sudden printing which occurs at low humidity, that is, curling after printing. The present invention relates to an ink jet recording sheet, which is excellent in stackability of a printed recording sheet.

[0002]

2. Description of the Related Art An ink jet recording system is a system in which minute droplets of ink are made to fly and adhere to a recording sheet such as paper by various operating principles to record images, characters, and the like. It has features such as easy colorization, great flexibility in recording patterns, and no need for development-fixing, and is rapidly spreading to various uses as a recording device for various figures including Chinese characters and color images.

Various efforts have been made in terms of equipment and ink composition so that high-quality paper or coated paper used in ordinary printing and writing can be used as a recording sheet used in the ink jet recording system. Have been. However, with the improvement of the performance of ink-jet recording apparatuses such as high-speed, high-definition or full-color apparatuses, and expansion of applications, it is required that recording sheets also have the following advanced characteristics. Became. (1) It is excellent in transportability under a wide range of temperature and humidity conditions when recording with a normal recording apparatus. (2) Through-through and cockling of the image recorded on the surface are prevented, and a high-quality recorded image can be obtained under a wide range of temperature and humidity conditions. (3) High recording dot density and image density. (4) Good image color and sharpness. (5) The print dot shape is good. (6) Good ink absorbency. (7) Good image storability such as water resistance, light resistance and ozone resistance of the recorded image. (8) In the case of a coat type recording sheet, the coating layer has high adhesiveness and has less powder fall. (9) The recording sheet itself is unlikely to yellow. (10) Compared with the dot diameter in the single-color portion, the dot diameter in the super-color portion is hardly changed, there is almost no bleeding in the super-color portion, and a high-definition recorded image can be obtained.

Heretofore, many proposals have been made focusing on improvement of specific performance among these. For example, JP-A-2-270588 discloses an ink jet recording sheet in which an ink receiving layer is formed separately on the front and back surfaces of a paper base, and JP-A-62-282967 discloses an ink jet recording sheet. There is disclosed an example having an ink holding layer and an ink transporting layer, and further having a curl suppressing layer having the same or similar physical properties as the ink holding layer. Also, Japanese Unexamined Patent Publication No.
JP-A-35184 discloses an example in which a recording material provided with an ink-receiving layer is provided with a curl prevention layer made of a resin such as polyacrylamide. Further, JP-A-4-298380 discloses an example in which a flat pigment is specified. There is disclosed an example in which a backside layer containing a binder having a glass transition point in a range is provided to eliminate the phenomenon of blurring of recording paper during printing and to improve the paper-passing suitability of a printer.

[0005]

A recording material provided with a curl suppressing / preventing layer (Japanese Patent Application Laid-Open No. 62-282967, etc.) can prevent curling of recording paper during printing by suppressing / preventing curling. A recording paper having a back layer to suppress (for example, Japanese Patent Application Laid-Open No. 4-298380) is intended to improve the transportability by improving the contact with the printer head by preventing the recording paper from being blurred during printing. However, in all printers using cut sheets, although problems during paper passing can be avoided, it is not possible to sufficiently suppress curl after printing in the drying process after rapid printing that occurs at low humidity,
If the curl occurs after printing, there is a problem that a stacking failure of the recording sheet occurs in the discharge tray to cause a paper jam, or the recording sheet becomes cylindrical and a recorded image cannot be seen.

An object of the present invention is to solve these problems and to provide an ink jet recording sheet having excellent stackability without curling after printing which occurs during a rapid drying process at low humidity. .

[0007]

In order to achieve this object, the present invention has at least one ink-receiving layer on a support, and at least one backcoat layer on the opposite surface. In the ink jet recording sheet, the support mainly comprises wood pulp and filler,
In 9 to 50 seconds human sizing degree basis weight 90 g / m ² base
The back coat layer has an aspect ratio of 5 as a pigment.
Only less than granular hydrated halloysite, shea <br/> Lil modified polyvinyl alcohol alone was used as a main component, silyl-modified polyvinyl alcohol hydrated halloysite 100 as an adhesive
An ink jet recording sheet characterized by being contained in an amount of 5 parts by weight or more and 20 parts by weight or less based on parts by weight.

[0008]

In the ink jet recording sheet of the present invention, the back coat layer is composed of granular hydrohaloysite and silyl-modified polyvinyl alcohol, and the silyl-modified polyvinyl alcohol is present in an amount of 5 to 20 parts by weight based on 100 parts by weight of the hydrohaloysite. It is necessary to contain it.

Although the mechanism for preventing curl after printing is not clear,
When the silyl-modified polyvinyl alcohol is dehydrated and shrunk under low humidity conditions, curl occurs on the back coat layer side opposite to the curl after printing, and this curl causes the binder component in the ink receiving layer after printing. This is considered to be due to resistance to curl caused by dehydration shrinkage. Further, the addition amount of the silyl-modified polyvinyl alcohol is 5 parts by weight or more and 20 parts by weight or more.
If the amount is less than 5 parts by weight, the curling suppression effect after printing cannot be obtained. If the amount exceeds 20 parts by weight, the curl toward the back coat layer under low humidity conditions becomes too large, and Causes paper passing failure.

When a tabular pigment having an aspect ratio of 5 or more is used, the pigment particles are displaced due to the shrinkage of the binder due to the shape characteristics of the particles, and the pigment particles move toward the back coat layer under low humidity conditions. On the other hand, the use of granular hydrohaloysite having an aspect ratio of less than 5 reduces the absorption of silyl-modified polyvinyl alcohol into the voids of the pigment particles, and efficiently forms a film between the particles. Since the particle shape is granular, it is considered that only the shrinkage behavior of the silyl-modified polyvinyl alcohol is exhibited without causing positional displacement of the pigment particles.

The support used in the present invention is mainly composed of wood pulp and filler, and has a Steckigt sizing degree of 90 basis weight.
It is preferably from 9 seconds to 50 seconds on a g / m ² basis, and when the sizing degree is less than 9 seconds, the penetration of the binder component in the coating solution into the support during coating of the back coat layer becomes large, Sufficient film formation is not achieved, and the desired effect cannot be obtained. On the other hand, if the size exceeds 50 seconds, the penetration of the binder component into the support is suppressed, but since the film formation is concentrated on the surface of the coating layer, the curl due to binder shrinkage at low humidity becomes too large, This can cause poor paper passing.

The ink receiving layer of the present invention can usually contain colloidal silica, white inorganic pigment, starch particles, aqueous polymer binder, cationic dye fixing agent, and other additives. Examples of the white inorganic pigment include calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, and synthetic. Amorphous silica, pseudo-boehmite, aluminum hydroxide, alumina, lithopone,
Zeolites, hydrolyzed halloysites, magnesium carbonate, magnesium hydroxide and the like can be mentioned. Of these, porous synthetic amorphous silica having a large pore volume is preferable.

The starch particles include corn (corn starch), wheat, barley, rice, potato,
Examples thereof include those produced from raw materials such as cassava (tapioca), sweet potato (sweet potato), and sago, or the following (a) to (li) obtained by processing these, and rice starch powder is particularly preferred. (A) Oxidized starch obtained by oxidation with an oxidizing agent such as sodium hypochlorite. (B) Acid-treated starch treated with hydrochloric acid or sulfuric acid. (C) Enzyme-treated starch. (D) Dialdehyde starch reacted with periodic acid. (E) Esterified starch such as acetylated starch, urea phosphorylated starch, and phosphorylated starch. (F) Etherified starch such as hydroxyalkylated starch and carboxyalkylated starch. (G) cationized starch. (H) Crosslinked starch such as formaldehyde crosslinked starch, epichlorohydrin crosslinked starch, and phosphoric acid crosslinked starch. (I) A graft-polymerized starch obtained by polymerizing an active site with a vinyl monomer such as acrylic acid, acrylonitrile, acrylamide, methacrylic acid ester, or vinyl acetate, or a cyclic monomer such as epoxide, episulfide, imine, or lactam.

Of these starch particles, those having little or no solubility in cold water are preferable for maintaining the particle shape in the ink jet recording sheet of the present invention.
It is desirable that water having a temperature of 40 ° C. or lower has almost no solubility and the gelatinization start temperature is 50 ° C. or higher. The starch particle diameter is preferably in the range of 1 to 10 μm in volume average particle diameter in order to properly secure both the ink absorption speed and amount and the quality of the recorded image.

The aqueous polymer binder used in the ink receiving layer of the present invention includes, for example, starch derivatives such as oxidized starch, etherified starch and phosphate esterified starch; cellulose derivatives such as carboxymethylcellulose and hydroxyethylcellulose; Polyvinyl alcohol derivatives such as gelatin, soy protein, polyvinyl alcohol or silyl-modified polyvinyl alcohol; conjugated diene copolymer latex such as polyvinyl pyrrolidone, maleic anhydride resin, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer An acrylic (co) polymer latex such as a polymer or copolymer of an acrylic ester and a methacrylic ester; a vinyl copolymer latex such as an ethylene-vinyl acetate copolymer; Is a functional group-modified (co) polymer latex with a monomer containing a functional group such as a carboxy group of these various (co) polymers; an aqueous adhesive such as a thermosetting synthetic resin such as a melamine resin or a urea resin; Acrylic ester such as methacrylate, polymer or copolymer resin of methacrylic ester; polyurethane resin,
Examples include unsaturated polyester resins, vinyl chloride-vinyl acetate copolymers, polyvinyl butyral, and alkyd resins. Among these aqueous polymer binders, polyvinyl alcohol or polyvinyl alcohol derivatives such as silyl-modified polyvinyl alcohol are preferred from the viewpoint of adhesive strength.

Examples of the cationic dye fixing agent include monomers and oligomers of primary to tertiary amines or quaternary ammonium salts which dissociate when dissolved in water to exhibit a cationic property.
A polymer can be mentioned, and it is preferably an oligomer or a polymer. In particular, the cation charge by the colloid titration method is 1 to 10 meq. / G of cationic dye fixing agent. 1 meq. If it is less than / g, the fixing performance of the water-soluble dye in the aqueous ink is inferior, and the water resistance of the recorded image decreases. In addition, 10 meq. If it exceeds / g, the water resistance of the recorded image can be improved with a small amount, but the light resistance and ozone resistance of the recorded image are inferior, and the yellowing of the recording sheet is deteriorated.

The above-mentioned colloidal silica, white inorganic pigment, starch particles, aqueous polymer binder and cationic dye fixing agent in the ink receiving layer of the ink jet recording sheet of the present invention are each one kind or a mixture of two or more kinds. You may.

In the ink receiving layer according to the present invention, the colloidal silica is used in an amount of 1 to 100 parts by weight of the white inorganic pigment.
It is preferably contained in an amount of 0 to 100 parts by weight, more preferably 20 to 50 parts by weight. Starch particles are 10 ~
100 parts by weight, 10 to 100 parts by weight of the aqueous polymer binder, and 0.1 to 5 g / m of the cationic dye fixing agent
^2. It is preferable that the cation charge amount is 0.1 to 50 meq / m ² .

In the support of the present invention, a sizing agent such as a neutral sizing agent, a polymer sizing agent or an acidic sizing agent can be used alone or in combination, and cationized starch is preferably used as a fixing agent for the sizing agent. Filler is pulp 100
It is preferable to use 10 parts by weight to 45 parts by weight based on parts by weight, and conventionally known pigments are used alone or in combination as white pigments. In addition, additives such as a retention aid, a coloring dye, and a sulfuric acid band as a fixing agent for the coloring dye may be used at all.

As a method for preparing the ink jet recording sheet of the present invention, for example, pulp fibers are defibrated to form a slurry, and fillers, sizing agents and other additives are added as required, and the paper is formed and dried by a paper machine. Alternatively, after papermaking, a water-soluble substance such as starch or a polymer substance is size-pressed, dried and machine-calendered to obtain a support sheet, and at least one layer is formed using a coating apparatus or a size press apparatus. The ink receiving layer and the back coat layer described above are provided. As the method for providing the ink receiving layer and the back coat layer, either an on-machine coater or an off-machine coater may be used. After coating, a calendar finish is further performed. The coating amount of the ink receiving layer is preferably in the range of 5 to 30 g / m ² ,
The coating amount of the back coat layer is preferably in the range of 5 to 15 g / m ² .

The support, the ink receiving layer and the back coat layer in the ink jet recording sheet of the present invention may further contain, as other additives, pigment dispersants, thickeners, flow improvers, defoamers, defoamers, A release agent, a foaming agent, a penetrating agent, an antibacterial agent, a waterproofing agent, a wet paper strength enhancer, a dry paper strength enhancer, a toning dye, and the like can be appropriately blended.

The aqueous ink in the present invention is a recording liquid comprising a colorant, a solvent and other additives. Examples of the colorant include a direct dye, an acid dye, a basic dye, a reactive dye, and a water-soluble dye such as a food colorant. Examples of the solvent for the aqueous ink include water and various water-soluble organic solvents. As other additives, for example, pH
Examples include regulators, sequestering agents, fungicides, viscosity modifiers, surface tension regulators, wetting agents, surfactants and rust inhibitors.

[0024]

EXAMPLES The present invention will be described below with reference to examples of the present invention, but the present invention is not limited to these examples. Further, “parts” and “%” shown in the examples are parts by weight and% by weight unless otherwise specified.

Example 1 67 parts of LBKP of 450 ml of CSF, 45 degrees of freeness
In a pulp slurry consisting of 8 parts of NBKP of 0 ml CSF, 0.6 parts of cationic starch and 10 parts of heavy calcium carbonate were added.
, The pH of the pulp slurry was adjusted to 8.
2 and the paper was dried with a Fourdrinier paper machine, and then the aqueous solution of oxidized starch dissolved in a size press was solidified at 5 g / m2 on both sides.
^The resultant was impregnated and dried to obtain a coating base paper having a basis weight of 95 g / m ² . The resulting coated base paper had a Stöckigt sizing degree of 10 seconds.
20 parts of colloidal silica (Snowtex-O, manufactured by Nissan Chemical Co., Ltd.), 75 parts of synthetic amorphous silica (Fine Seal X37B, manufactured by Tokuyama Soda Co., Ltd.), 75 parts of rice starch powder (Micropearl, manufactured by Shimada Chemical Co., Ltd., average particle diameter: 4.9 μm) 25 parts, polyvinyl alcohol (PVA117, manufactured by Kuraray Co., Ltd.) 30 parts and a cationic dye fixing agent (Sumiretz Resin 1001, manufactured by Sumitomo Chemical Co., Ltd., cationic charge amount) A coating solution having a concentration of 18% containing 3.5 parts of (3.5 meq./g) was applied by an air knife coater so as to have a solid content of 8 g / m ^2, and dried by setting the maximum temperature of hot air to 120 ° C. or higher. Further, on the other side of the coated paper, as a back coat layer, hydrated halloysite (Ina Kaolin, manufactured by Oharu Chemical Industry Co., Ltd., aspect ratio less than 5,
A 25% concentration coating solution containing 100 parts of an average particle size of 5 μm) and 15 parts of silyl-modified polyvinyl alcohol (R polymer 1130, manufactured by Kuraray Co., Ltd.) is applied using an air knife coater to a solid content of 10 g / m ^2. And dried. Further, the ink jet recording sheet of Example 1 was finished by a super calender finish.

Example 2 In Example 1, as a back coat layer, 100 parts of hydrohaloysite (Ina Kaolin, manufactured by Oharu Chemical Industry Co., Ltd., aspect ratio less than 5, average particle diameter 5 μm), silyl-modified polyvinyl alcohol (R polymer 1130) (Manufactured by Kuraray Co., Ltd.) The same procedure as in Example 1 was carried out, except that a coating solution having a concentration of 20% and a solid content of 5 g / m ² was applied using an air knife coater and dried. 2 was obtained.

Comparative Example 1 In Example 1, a flat delaminated kaolin clay (Nuclay, manufactured by Engelhard Co., aspect ratio 5 to 50, particle size 2 to 20 μm) was used as a back coat layer.
0 parts, silyl-modified polyvinyl alcohol (R polymer 1
Comparative Example 25 was prepared in the same manner as in Example 1 except that a coating liquid having a concentration of 25% and 15 parts thereof was blended with an air knife coater to a solid content of 10 g / m ² and dried. The ink jet recording sheet of Example 1 was obtained.

[0028] In Example 4 Example 1, except that the added amount of alkyl ketene dimer and 0.3 part upon base paper papermaking, in the same manner as in Example 1, to obtain an ink jet recording sheet of Example 4. The resulting coated base paper had a Stöckicht sizing degree of 60 seconds.

[0029]

[0030] In Comparative Example 2 Example 1, except that the 3 parts of the amount of the silyl-modified polyvinyl alcohol backcoat layer, to obtain an ink jet recording sheet of Comparative Example 2 in the same manner as in Example 1. Comparative Example 3 In Example 1, as the back coat layer, 100 parts of hydrolyzed halloysite (Ina Kaolin, manufactured by Oharu Chemical Industry Co., Ltd., aspect ratio less than 5, average particle diameter 5 μm), silyl-modified polyvinyl alcohol (R polymer 1130, Kuraray Co., Ltd.) Coating solution of Comparative Example 3 was prepared in the same manner as in Example 1 except that a coating solution having a concentration of 20% and containing 25 parts thereof was coated with an air knife coater to a solid content of 10 g / m ² and dried. A recording sheet was obtained.

Example 3 Freeness: 430 ml LBKP 90 parts CSF, freeness: 48
To a pulp slurry consisting of 10 parts of NBKP of 0 ml CSF, 0.8 parts of cationic starch, 15 parts of talc, 10 parts of heavy calcium carbonate, 15 parts of light calcium carbonate, and 0.1 part of alkyl ketene dimer were added, and the pH of the pulp slurry was added. Was adjusted to 8.2, formed and dried with a fourdrinier paper machine, and subsequently impregnated and dried with an aqueous solution of oxidized starch dissolved in a size press so that the solid content was 5 g / m ² on both sides, followed by machine calendering. Thus, a coated base paper having a basis weight of 90 g / m ² was obtained. The resulting coated base paper had a Stighit sizing degree of 50 seconds. Colloidal silica (Snowtex-O, manufactured by Nissan Chemical Co., Ltd.) is coated on the surface of the coated base paper having a large filler distribution.
0 parts, synthetic amorphous silica (Fine Seal X37B, manufactured by Tokuyama Soda Co., Ltd.) 75 parts, synthetic amorphous silica (Syloid 6
20, 25 parts by Fuji Devison), 40 parts of polyvinyl alcohol (PVA117, manufactured by Kuraray) and 30 parts of cationic dye fixing agent (Sumiretz Resin 1001, manufactured by Sumitomo Chemical Co., Ltd., cationic charge: 3.5 meq./g) Was coated with an air knife coater so that the solid content became 8 g / m ^2, and the hot air was dried at a maximum temperature of 120 ° C. or higher. Further, on the other side of the coated paper, as a back coat layer, hydrated halloysite (Ina Kaolin, manufactured by Oharu Chemical Industry Co., Ltd., aspect ratio less than 5,
A 25% concentration coating solution containing 100 parts of an average particle diameter of 5 μm) and 5 parts of silyl-modified polyvinyl alcohol (R polymer 1130, manufactured by Kuraray Co., Ltd.) is applied using an air knife coater to a solid content of 15 g / m ^2. And dried. Further, the ink jet recording sheet of Example 3 was subjected to a super calendar finish.

[0032]

Comparative Example 4 In Example 3, polyvinyl alcohol (P) was used instead of silyl-modified polyvinyl alcohol for the back coat layer.
Example 3 except that VA105 (manufactured by Kuraray) was used.
In the same manner as in the above, an ink jet recording sheet of Comparative Example 4 was obtained.

<Performance> The performance of the ink jet recording sheet was measured by the following method. (1) Blank paper curl Under an environmental condition of 15 ° C. and 10% RH, 100 sheets were laminated with the ink receiving layer surface facing upward and left for one day. Indicated by value. In addition, the curl toward the ink receiving layer side is indicated by +, and the curl toward the back coat layer side is indicated by-. As the situation of white paper curl, curling toward the back coat layer side rather than the ink receiving layer surface side is preferable in terms of transportability. However, if the curl exceeds 10 mm, poor transportability occurs. (2) Curl after printing Using a color inkjet printer (IO-720, manufactured by Sharp Corporation) under the environmental conditions of 15 ° C. and 10% RH,
Solid printing was performed on the entire surface of the A4 size sheet in a single color of cyan, and the state after standing for 30 minutes was observed. Evaluation criteria a: Lifting of the four corners is not recognized, or even if recognized, the entire recorded image is observed. b: Lifting of four corners is recognized, but more than half of the recorded image is observed. c: The recording sheet is cylindrical, and the recorded image cannot be observed at all, or even less than half if observed.

(3) Loadability The loadability is determined under the environmental conditions of 15 ° C. and 10% RH by a color ink jet copying machine (Pixel Jet, manufactured by Canon Inc.).
In this cassette, 50 ink jet recording sheets were set, and the number of sheets stacked on the paper discharge tray when 10 solid black images were continuously copied was measured. Evaluation criteria A: The number of loaded sheets is 10. B: The loading number is 8 to 9. C: The number of stacked sheets is 7 or less.

Table 1 shows the measurement results of the performances of the ink jet recording sheets of Examples 1 to 4 and Comparative Examples 1 to 4 .

[0037]

[Table 1]

[0038]

The ink jet recording sheet of the present invention is
The back coat layer is composed of granular hydrohaloysite and silyl-modified polyvinyl alcohol, and silyl-modified polyvinyl alcohol is added to hydrohaloysite 100 parts by weight,
By containing 5 parts by weight or more and 20 parts by weight or less, curling after printing under low humidity conditions is suppressed, thereby solving the problem of poor observation of a recorded image due to tube formation after printing and discharging tray after recording. The above-mentioned excellent stackability makes it possible to perform continuous recording without causing a paper ejection failure due to poor stackability. In other words, for the first time according to the present invention, a recording sheet for ink jet recording using an aqueous ink is excellent in curl after printing at low humidity, and particularly in an ink jet recording apparatus using a cut sheet, excellent in stackability after recording even in low humidity. Inkjet recording sheet is provided.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-221115 (JP, A) JP-A-7-101142 (JP, A) JP-A-7-242049 (JP, A) JP-A-6-201 227113 (JP, A) JP-A-6-171206 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/00

Claims (1)

(57) [Claims] An ink jet recording sheet having at least one or more ink-receiving layers on a support and at least one backcoat layer on the opposite surface, wherein the support mainly comprises wood pulp and filler. Ingredients and wonderful
In 9 to 50 seconds human sizing degree basis weight 90 g / m ² base
The back coat layer has an aspect ratio of 5 as a pigment.
Only less than granular hydrated halloysite, shea <br/> Lil modified polyvinyl only as a main component an alcohol, the sheet <br/> Lil modified polyvinyl alcohol the hydrated halloysite 1 as an adhesive
An ink jet recording sheet comprising 5 parts by weight or more and 20 parts by weight or less based on 00 parts by weight.