JP2006110848A - Inkjet recording embossed sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording sheet, which is excellent in inkjet recordability, has a peculiar texture and in which an embossing pattern is stressed in an inkjet recording sheet, which is formed by providing at least one coating layer on one side or both the sides of a base sheet mainly made of a woodpulp and a filler. <P>SOLUTION: Microcapsules containing an inorganic solid acid and a colorless dye, which develops color in contact with the inorganic solid acid, are included in an inkjet recording coating layer so as to perform embossing to the surface of the coating layer. The preferable content ratio of the inorgaanic solid acid to the colorless dye is 0.1-1.0 pts. mass of the colorless dye to 100 pts. mass of inorganic solid acid. Further, the preferable inorganic solid acid is silica. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink-jet recording mold sheet provided with a coating layer for ink-jet recording on one or both sides of a base paper and subjected to a mold process.

  The ink jet recording system is a method for recording images, characters, etc. by ejecting micro droplets of ink by various operating principles and attaching them to a recording sheet such as paper or film. It is easy to create, has great flexibility in recording patterns, and does not require development-fixing, and has rapidly spread to various uses as a recording device for various figures and color images including kanji. In addition, an image formed by the multi-color ink jet method can obtain an inferior recording as compared with printing by the multi-color printing by the plate making method or the multi-color color photographic method. In applications where the number of copies to be produced is small, it is being applied widely to the field of full-color image recording because it is less expensive than with photographic technology.

  In addition, with the widespread use of digital cameras, high-definition full-color inkjet recording images can be easily obtained. In recent years, inkjet recording sheets are often used as New Year's postcards, summer greeting cards, greeting cards, and the like. It has become. In addition, as the market for inkjet recording expands in this way, there are cases where inkjet recording paper with a unique image quality and characteristic texture is required. Development is expected. With respect to the ink jet recording paper having such a unique texture, a method for obtaining the texture and feel of a picture postcard or photographic print has been disclosed (for example, see Patent Documents 1 and 2).

  In Patent Document 2, as a method for obtaining an ink jet recording paper having a unique texture, a method of applying a pattern by a dandy roll on the paper machine wire in advance on the surface of the base paper before providing the ink receiving layer, Although it has been proposed to apply a concavo-convex pattern by any method selected from a method of applying a press mark in a wet paper state with a pressed press roll and a method of processing a dry paper with an embossing calendar and applying an embossing mark. In these methods, when the ink receiving layer is provided, there is a problem that uneven coating due to the unevenness of the surface of the base paper occurs, and a uniform and high quality printed image cannot be obtained.

Further, a method of performing molding after providing an ink receiving layer on the surface of the support is also conceivable. A typical example is a treatment with an embossing roll in which irregularities are engraved on the roll surface. The embossing roll is pressed against the surface of the ink receiving layer, resulting in a dent perpendicular to the surface of the receiving layer, and ink does not adhere to the side surface of the recess during ink jet recording, resulting in print unevenness and white spots on the recorded image. When the embossing roll is weakened to prevent printing unevenness and white spots in the recorded image, the unevenness of the molding is reduced and the desired texture cannot be obtained.
Japanese Patent Laid-Open No. 11-188966 Japanese Patent No. 3282761

  Accordingly, an object of the present invention is to provide an ink jet recording sheet that is excellent in ink jet recording suitability, has a unique texture, and has an embossed pattern.

  As a result of intensive studies, the present inventors have found that in an ink jet recording sheet in which at least one or more ink jet recording coating layers are provided on one or both sides of a base paper mainly composed of wood pulp and filler, The present inventors have found that the above-mentioned problems can be solved by including microcapsules encapsulating an inorganic solid acid and a colorless dye that develops color upon contact with the inorganic solid acid, and performing a molding process on the surface of the coating layer. The amount of microcapsules containing colorless dye in the coating layer is about 0.1 to 5.0 parts by weight as a colorless dye with respect to 100 parts by weight of the inorganic solid acid, but 0.1 to 1.0 parts by weight preferable. Silica is most preferable as the inorganic solid acid.

  When the coating layer containing inorganic solid acid and colorless dye-encapsulated microcapsules is molded, the microcapsule breaks and the encapsulated colorless dye and the inorganic solid acid come into contact with each other, resulting in a colored image according to the pattern of the molding The embossing pattern can be emphasized.

  As the coating liquid used for forming the coating layer for inkjet recording of the present invention, in addition to the colorless dye-encapsulated microcapsules, the main component is a pigment, an adhesive, the additive is an ink fixing agent such as a cationic resin, and the pigment dispersion Agent, thickener, fluidity improver, surfactant, antifoaming agent, antifoaming agent, penetrating agent, coloring dye, coloring pigment, fluorescent whitening agent, pH adjusting agent, ultraviolet absorber, antioxidant, antiseptic An agent, an antifungal agent, a water resistance agent, a wet paper strength enhancer, a dry paper strength enhancer, and the like are appropriately used.

  As a microcapsule film material containing a colorless dye and a manufacturing method thereof, a known technique can be applied, but it is preferable to select a method capable of producing a water-resistant film material. In general, a solution in which a colorless dye is dissolved in a water-insoluble high-boiling organic solvent is dispersed in the aqueous phase as microdroplets, and an insoluble synthetic resin film is formed around the microdroplets to produce microcapsules. Can do. An in-situ polymerization method in which an insoluble film is formed by adding an initial condensate such as melamine-formaldehyde resin, urea-formaldehyde resin, etc. from the aqueous phase side and forming an insoluble film; Interfacial polymerization methods for forming an insoluble synthetic resin film at the interface are known, and these are widely used in the production of microcapsules for carbonless pressure-sensitive copying paper.

  As the water-insoluble high-boiling organic solvent, for example, those known as the inner phase oil of microcapsules for carbonless pressure-sensitive copying paper can be used, such as phenylxylylethane, phenylethylphenylethane, phenylcumylethane, Aromatic compounds such as diarylalkanes such as phenyl sec-butylphenyl ethane, alkylated biphenyls such as sec-butyl biphenyl and isopropyl biphenyl, alkylated naphthalenes such as diisopropylnaphthalene, alkylated terphenyl, normal paraffin, isoparaffin, chlorine Paraffin oil such as modified paraffin, naphthenic oil, higher fatty acid ester solvent and the like.

  As the colorless dye, those known for carbonless pressure-sensitive copying paper and thermal recording paper can be used. Typical examples include triphenylmethane phthalide, fluoran, phenothiazine, indolyl phthalide, and indolyl. Examples include azaphthalide, leucooramine, spiropyran, rhodamine lactam, and triphenylmethane.

  The size (volume average particle diameter) of the microcapsules used in the present invention is preferably 2 to 6 μm, and particularly preferably 3 to 5 μm. Depending on the thickness of the microcapsule film material, if the average particle size of the microcapsules is too large, when the calendering is performed after forming the recording coating layer in the production of the ink jet recording sheet, There is a possibility that a part of the ink may be destroyed to impair ink jet recording suitability, or coloring stains may be generated on the entire surface. In addition, when the microcapsule average particle size is too small, the probability that the microcapsules are broken is small, and the emphasis effect of the patterning pattern is difficult to obtain.

  As the pigment used in the coating liquid for forming a coating layer for inkjet recording, an inorganic solid acid having an acid point on the particle surface and suitable for inkjet recording is selected. Examples thereof include silica, alumina, aluminosilicate, and the like, and silica such as synthetic amorphous silica, colloidal silica, and vapor phase method silica is particularly preferable. Also, light calcium carbonate, heavy 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, colloidal alumina, White inorganic pigments such as pseudoboehmite, aluminum hydroxide, alumina, lithopone, zeolite, hydrous halloysite, magnesium carbonate, magnesium hydroxide can also be used in combination.

  Depending on the ratio of the colorless dye to the inorganic pigment in the coating layer for inkjet recording, the color density of the desired patterning pattern can be changed, and the color hue of the patterning pattern can be changed by changing the type of colorless dye. it can. The colorless dye is used in an amount of about 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the inorganic pigment. If the color density of the patterning pattern is high, the inkjet recording image may be unsightly. Although depending on the coloring performance of the inorganic pigment or the colorless dye, the colorless dye is preferably 0.1 to 1.0 part by mass, and most preferably 0.2 to 0.5 part by mass.

  Examples of the adhesive used in the coating liquid for forming a coating layer for inkjet recording include starch derivatives such as oxidized starch, etherified starch, and phosphate esterified starch; cellulose derivatives such as carboxycellulose and hydroxyethylcellulose; casein, gelatin, and soybean Protein, polyvinyl alcohol, various modified polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl butyral, maleic anhydride resin, unsaturated polyester resin, vinyl chloride-vinyl acetate strong polymer, polyurethane resin; styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer Conjugated diene copolymer latexes such as polymers; vinyl copolymer latexes such as acrylate and methacrylate polymers and copolymers; carboxy groups of these various copolymers, etc. Functional group-containing monomer by a functional group-modified copolymer latex; melamine resins, water-based adhesives of thermosetting synthetic resins such as urea resins.

  As a coating method for providing the coating layer for inkjet recording of the present invention on the base paper, blade coater, air knife coater, curtain coater, bar coater, gravure coater, roll coater, bill blade coater, gate roll coater, transfer roll coater In view of ink absorption unevenness during ink jet printing, it is particularly preferable to use a curtain coating method for forming the ink jet recording coating layer.

The coating amount of the inkjet recording coating layer on the base paper is preferably 5 to 30 g / m ² (dry mass solid content), and most preferably 6 to 15 g / m ² .

  Also, in order to further improve the printing characteristics, appearance, etc., after performing smoothing processing such as supercalender and soft calendering to the extent that the colorless dye-containing microcapsules are not destroyed, it may be possible to perform mold processing. it can.

  As the opposite side of the coating layer for inkjet recording, it is not necessary to provide a coating layer. However, in applications where offset printing is performed, coating is performed in order to improve offset printing suitability such as ink fillability and printing durability. A layer can be provided. Its composition is mainly composed of water-soluble polymer resin, pigment, antifoaming agent, antifoaming agent, fluorescent brightening agent, ultraviolet absorber, antioxidant, antistatic agent, antiseptic, antifungal agent, water resistance An agent and the like can be appropriately used as necessary.

  Pulp used for the base paper of the present invention is chemical pulp such as hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), hardwood bleached sulfite pulp (LBSP), softwood bleached sulfite pulp (NBSP), mechanical pulp, etc. Mechanical pulp such as pulp (GP), thermomechanical pulp (TMP), and chemical thermomechanical pulp (CTMP), non-wood pulp such as bamboo, abaca, kenaf, esparto, and bagasse, recycled paper recycled pulp, and the like are used.

  Additives used for base paper include additives usually used in papermaking, for example, calcium carbonate, talc, kaolin, calcined kaolin, titanium oxide, etc. as fillers, rosin, reinforced rosin, modified rosin as internal sizing agents , Alkenyl succinic anhydride (ASA), neutral rosin, alkyl ketene dimer (AKD), etc. Examples of dry paper strength enhancers include acrylic amide resin, modified polyacrylamide resin, cationized starch, polyacrylamide starch derivative, polyvinyl alcohol Derivatives and the like are used, and in addition, antifoaming agents, dyes, coloring pigments, fluorescent brighteners, wet paper strength improvers, freeness improvers, yield improvers, and the like can be appropriately used.

  As the water-soluble polymer resin used for the size press solution of the base paper, a water-soluble adhesive used for forming a coating layer for inkjet recording can be used, but if an adhesive having a strong film forming property is used, Since ink absorbability deteriorates and ink overflow occurs, starch derivatives such as oxidized starch, etherified starch, and phosphate esterified starch that are relatively weak in film forming property are preferably used. In addition, a surface sizing agent usually used in papermaking can be used in combination, and if necessary, an antifoaming agent, a dye, a coloring pigment, a fluorescent brightening agent, a cationic fixing agent, a water-soluble polyvalent metal salt, etc. are used in combination. It is also possible.

  Examples of cationic resins for fixing anionic ink-jet ink components and improving the water resistance of water-based inks include polyamine resins, polydiallylamine resins, polyamide / epoxy resins, and polyamine / epichlorohydrin resins. And polyamide polyamine / epichlorohydrin resin, dimethyldiallylammonium chloride / sulfur dioxide copolymer and the like. A particularly preferred compound is a dimethylamine / epichlorohydrin resin.

The basis weight of the base paper is not particularly limited, but when a base paper of 150 to 250 g / m ² is used, an effect of molding is easily obtained.

  The ink jet recording mold sheet of the present invention is manufactured by providing an ink jet recording coating layer on one or both sides of a base paper and then performing a molding process on the surface of the coating layer desired to be molded with an embossed calendar. The embossing process is obtained by engraving the embossing pattern and pressing an embossing roll having protrusions against the surface of the ink jet recording layer to form a recess on the surface of the recording layer.

  The embossing roll can change the processing state according to the tip shape of the embossing roll, the unevenness depth, the embossing roll pressurizing pressure at the time of paper feeding, the paper feeding speed, the roll temperature, etc. These conditions are adjusted according to the degree of color development and the influence on the back surface.

  The ink-jet recording template sheet according to the present invention is used as an ink-jet recording paper having a unique texture, but can also be applied to prevent falsification and counterfeiting by using a coloring patterning pattern.

  The preferred embodiments of the present invention and the excellent effects thereof will be specifically described below with the most representative examples. In the following, all parts are parts by mass, and all% are% by mass.

[Preparation of base paper]
Add 8 parts of talc, 0.5 part of rosin emulsion sizing agent, and 2.0 parts of sulfuric acid band to the pulp slurry obtained by beating 90 parts of LBKP and 10 parts of NBKP until the freeness reaches 500 mlcsf, and dilute to 1%. Then, a base paper having a basis weight of 180 g / m ² was made with a long paper machine, and a base paper was prepared by treating it with an inked size press method using a 5% oxidized starch solution as a size press solution.

[Production of water-insoluble organic solvent-encapsulated microcapsules]
A solution obtained by heating and dissolving 8 parts of 3-dibutylamino-6-methyl-7-anilinofluorane (manufactured by Yamamoto Kasei Co., Ltd.) in 92 parts of phenylxylylethane (SAS N-296, manufactured by Nippon Petrochemical Co., Ltd.) is styrene. -Gradually added to 220 parts of 5% aqueous solution of maleic anhydride copolymer under strong stirring, and stirring was continued until the volume average particle size became 5 µm to prepare an emulsion. Melamine-formaldehyde initial condensate aqueous solution obtained by heating and dissolving 16 parts of melamine, 30 parts of 37% formaldehyde aqueous solution and 40 parts of water is added to the previously prepared emulsion and stirred at a temperature of 70 ° C. for 2 hours. A colorless dye-containing microcapsule solution was obtained.

[Preparation of coating solution for inkjet recording coating]
Ammonia 0.5 part Synthetic amorphous silica (Fine Seal X-37B: manufactured by Tokuyama Co., Ltd.) 50 parts Polyvinyl alcohol (PVA117: manufactured by Kuraray Co., Ltd.) 30 parts Cationic fixing agent (Sumilets Resin 1001: Sumitomo Chemical Industries) Co., Ltd.) 20 parts Colorless dye-encapsulated microcapsules 4 parts The above mixture was mixed to obtain a coating liquid for ink-jet recording having a dry solid content of 20%.

[Preparation of inkjet recording sheet]
After coating and drying 10 g / m ² (dry solid) of the inkjet recording coating layer coating liquid on the base paper, the embossing calender device is used to mold the inkjet recording layer surface at a linear pressure of 60 kN / m. The ink jet recording type | molding sheet | seat of Example 1 was obtained.

  A template for ink-jet recording of Example 2 was obtained in the same manner as in Example 1 except that 2 parts of the colorless dye-containing microcapsules were used.

  A template for ink-jet recording of Example 3 was obtained in the same manner as in Example 1 except that 15 parts of the colorless dye-containing microcapsules were used.

  A template sheet for ink-jet recording of Example 4 was obtained in the same manner as Example 1 except that the molding pressure by the embossing calendar apparatus was changed to a linear pressure of 30 kN / m.

  A template for ink-jet recording of Example 5 was obtained in the same manner as Example 1 except that 35 parts of synthetic amorphous silica and 15 parts of light calcium carbonate (Brilliant 15: manufactured by Shiraishi Calcium Co., Ltd.) were used. .

(Comparative Example 1)
The ink-jet recording paper of Comparative Example 1 was used without performing the molding process in Example 1.

(Comparative Example 2)
A template for inkjet recording of Comparative Example 2 was obtained in the same manner as in Example 1 except that the microcapsules were not used.

(Comparative Example 3)
A template for ink jet recording of Comparative Example 3 was obtained in the same manner as in Example 4 except that the microcapsules were not used.

  The inkjet recording sheets obtained in Examples 1 to 5 and Comparative Examples 1 to 3 were evaluated by the following methods, and the results are shown in Table 1.

Evaluation method <Shaping pattern visibility>
The surface of the ink jet recording coating layer that had been subjected to the mold forming treatment was visually observed, the visibility of the mold pattern was determined according to the following criteria, and the results are shown in Table 1.
A: The color density is high, and the patterning pattern can be clearly seen.
B: Although the color density is low, the patterning pattern is easy to recognize.
C: Slightly colored, and the patterning pattern is emphasized compared to D.
D: The typing pattern is difficult to recognize.
A, B, and C are practical levels.

<Inkjet recording suitability>
Set each inkjet recording paper cut to postcard size on an inkjet printer (Canon PIXUS950i), print a test pattern on the entire surface by borderless printing, visually fine image, uneven printing of inkjet printing, The white spots were examined, and comprehensively evaluated according to the following criteria as recording suitability. The results are shown in Table 1.
A: Extremely excellent.
B: Printing unevenness and white spots are not observed, but the image definition is slightly inferior to A.
C: Some printing unevenness (white spots) is observed, but at a practical level.
D: Printing unevenness (white spots) is observed on the entire surface, which is practically hindered.

<Texture of inkjet printing image>
Using the above-mentioned ink-jet printer, images of landscape paintings were printed on each ink-jet recording paper, and 10 people visually evaluated whether or not an expression effect similar to a painting for appreciation was obtained. The improvement effect was determined according to the following criteria, and the results are shown in Table 1.
A: Extremely excellent. Nine or more people recognize the improvement effect.
B: 6-8 persons recognize the improvement effect.
C: 3-5 persons recognize the improvement effect.
D: Two or fewer people recognized the improvement effect. This includes cases where no improvement is observed.

  As is clear from the above results, it can be seen that the ink jet recording mold sheet of the example is excellent in ink jet recording suitability, and an ink jet recording sheet having a unique texture can be obtained. On the other hand, an ink jet recording paper without a mold has good ink jet recording suitability, but it is a flat image and a unique texture cannot be obtained. In addition, in the ink-jet template sheet of the comparative example, when the mold processing pressure is increased to increase the pattern, white spots are generated in the image. When the mold processing pressure is decreased, the white spots are reduced but a unique texture is obtained. I can't. In addition, in the prescription in which a part of silica is replaced with light calcium carbonate, it is understood that the use of silica is superior because the color developability is lowered and the ink jet recording suitability is also lowered.

  As is clear from the above examples, a unique texture is obtained by performing a molding process on the coating layer for inkjet recording containing the microcapsules encapsulating the inorganic solid acid and the colorless dye that develops color upon contact with the inorganic solid acid. Ink-jet recording images having an image quality can be obtained, and can be used for ink-jet postcards and card applications, and can also be applied to applications such as falsification prevention and forgery prevention.

Claims (3)

  An inkjet recording sheet having at least one coating layer on one or both sides of a base paper mainly composed of wood pulp and filler, wherein the coating layer is in contact with an inorganic solid acid and an inorganic solid acid A mold-forming sheet for ink-jet recording, comprising a microcapsule encapsulating a colorless dye that develops a color, and performing a molding process on the surface of the coating layer.   The type | molding sheet | seat for inkjet recording of Claim 1 in which the coating layer for inkjet recording has 0.1-1.0 mass part of colorless dyes with respect to 100 mass parts of inorganic solid acids.   The ink-jet recording template sheet according to claim 1 or 2, wherein the inorganic solid acid is silica.