JP5766474B2 - Ink jet recording sheet and manufacturing method thereof - Google Patents

Description

  The present invention relates to an ink jet recording sheet and a method for producing the same, and in any recording system using any of dye ink and pigment ink, there is no blur, the printing density is high, the water resistance of the printing portion, the printing portion uniformity, The present invention relates to an ink jet recording sheet that is excellent in coating suitability and has a phenomenon that a white paper portion is yellowed during long-term posting and / or storage (hereinafter referred to as white paper yellowing).

  In recent years, it has become possible to obtain clear images and excellent print quality by technological progress of ink jet printers that produce hard copies at high speed. Along with this, in order to further improve the printing quality, recording paper having higher characteristics has been required, and various recording papers have been developed.

  Aqueous inks for inkjet printers are classified into dye inks using dyes and pigment inks using pigments, and dye inks are mainly used from the viewpoint of sharpness. However, in recent years, since it has come to be used as a large-sized poster for outdoor display, dye ink is oxidized by ultraviolet rays, ozone, etc. when displayed for a long time, and the image fades and looks bad. There is a drawback that printing light resistance cannot be obtained.

  On the other hand, the pigment ink has a feature that the storability of the printing portion is excellent, and the pigment particle of the pigment ink is very large compared to the size of the dye particle of the dye ink. However, there is a problem that a clear printed image cannot be obtained.

  Inkjet printers are expanding from printing applications such as documents to wide advertising applications such as posters. For printing advertisements and the like, those that can be printed on wide recording paper called inkjet plotters are usually used. These ink jet plotters are often used for outdoor posting, and pigment inks with excellent storability in the printed part are mainly used. Because they are used for advertising, it is necessary to clearly check the image even from a distance. The discharge amount tends to increase.

  Since the ink characteristics are different, for example, the pigment particles of the pigment ink are very large compared to the size of the dye particles of the dye ink, dedicated ink jet recording papers are provided as recording media. In general, recording paper for pigment ink is designed to have high ink absorbency, whereas for dye ink, the ink absorbency is lower than that for pigment ink, and instead it is designed by selecting an ink fixing agent. It has become. If these are recorded in an incorrect combination, only a recorded matter in which the quality such as image density and blurring is impaired can be obtained. For example, when printing on a conventional ink jet recording paper for dye ink using pigment ink, the pigment ink is not absorbed, unevenness occurs in the printing portion, ink particles are not fixed well, and the printing portion is touched with a finger or the like. When rubbed, the ink is peeled off, causing a problem in practical use.

  In addition, the storability of the printing part can be obtained by using pigment ink, but the storability of the blank paper part has not been solved yet. Specifically, when storing inkjet recordings in a clear file made of polypropylene resin for a long period of time, or when wrapping the adhesive tape with the one-pump so that it touches the surface of the ink receiving layer, a blank sheet at the end that touches the air In some cases, yellowing occurs in the area, and the quality of the recorded matter may be significantly impaired. This is considered to occur as a result of an antioxidant or the like contained in the clear file acting in the presence of air and components contained in the ink jet recording sheet.

  For applications that combine offset printing, which is suitable for handling a large amount of fixed information, and inkjet printing, which is suitable for handling variable information, it is a single-sided coated product, and is printed on the coated surface when offset printed on the back side. In addition, when the back surface is stored with being overlaid, there is a problem that the coated surface turns yellow due to the influence of the offset printing ink. Therefore, in addition to excellent printability, there has been a high demand for ink jet recording paper having excellent white paper storage stability.

  In addition, with the aim of improving the strength of the coating film and increasing the efficiency of the drying capacity, the concentration of the coating liquid has been increasing. Etc., and has difficulty in coating suitability. Furthermore, if there is uneven coating, the ink absorbability becomes non-uniform, and there is a problem that density non-uniformity in which the density becomes non-uniform in the printed part tends to occur, and both coating suitability and quality are balanced. The actual situation is that an inkjet recording sheet has not yet been obtained.

  Because of the above circumstances, ink jet recording paper that has no ink smudging when printed with either dye ink or pigment ink, has high printing density, is excellent in water resistance of the printing portion, and is excellent in uniformity of the printing portion, and has little blank yellowing. There is a high demand for and many proposals have been made to meet such a demand.

  As an inkjet recording sheet printed with dye ink and exhibiting excellent water resistance and printing density, a method of containing a water-soluble metal salt or metal oxide in the coating liquid (for example, see Patent Documents 1 to 9) and the like. Although it has been proposed, color developability when printed with pigment ink is insufficient, color developability when printed with dye ink and print storage stability (water resistance, light resistance, ozone resistance), Even if printing is performed with either dye ink or pigment ink, an ink jet recording sheet having excellent recording ability cannot be obtained.

In addition, as a method for solving the blank yellowing of ink jet recording paper, ink absorbability, and printing unevenness, a method of applying an ink receiving layer forming coating solution containing an ammonium compound. (For example, refer to Patent Document 10.) Further, as a method for solving the light resistance of an image, an ink receiving layer containing a water-soluble metal salt (for example, refer to Patent Document 11) is disclosed. However, printing with either dye ink or pigment ink has no ink bleeding, high print density, excellent water resistance of the print area, excellent uniformity of the print area, and is effective in improving the yellowing of blank paper. There wasn't.
As a cause of yellowing of the blank portion of the inkjet recording sheet, an antioxidant contained in a file such as polyethylene and polypropylene, a tape adhesive, glue, rubber, etc. is an inorganic material having a high specific area that forms an ink receiving layer It is considered that it is volatilized and adsorbed on the pigment and oxidized on the ink jet recording sheet. Polypropylene, polyethylene, and the like are often mixed with an antioxidant having a phenol group in the molecule such as butylhydroxytoluene (hereinafter abbreviated as BHT), and these phenolic antioxidants cause an oxidizing action, It is well known that the quinone structure turns yellow. In addition, the phenolic antioxidant may be colored by nitrogen oxides. In order to solve these problems, the synthetic amorphous silica has an oil absorption of 50 ml / 100 g or more and less than 160 ml / 100 g, and the synthetic amorphous silica has an oil absorption of 200 ml / 100 g or more and less than 400 ml / 100 g. A recording sheet having a mass ratio to silica of 1:10 to 1: 1 and containing an aqueous hindered amine light stabilizer in the ink receiving layer is disclosed (for example, see Patent Document 12).

Such yellowing of the blank sheet of the ink jet recording sheet is obtained by, for example, binding the recording sheet to a clear file containing 2,6-di-tert-butyl-4-methyl-phenol (hereinafter referred to as BHT). When stored, it can be inferred that BHT is transferred from the clear file to the ink receiving layer of the recording sheet. Therefore, when an ink jet recording sheet comes into contact with a familiar article containing a phenolic antioxidant represented by BHT, yellowing proceeds, and secondary factors such as ozone in the air, NO _x , SO _x and temperature and humidity It is thought that it is promoted more by.

  By the way, the yellowing caused by BHT has a history that has been taken up as a problem in the fiber and apparel industries for a long time, and has been found to become a compound having a stilbenequinone structure through an oxidation reaction. (For example, refer nonpatent literature 1, 2, 3, 4, 5).

  As an interesting proposal, in an ink jet recording sheet, a spot test using [4,4′-methylene-bis-2,6- (di-tert-butylphenol)] (hereinafter referred to as BHT 2) was conducted in an ink. There is a method for evaluating the catalytic activity of a porous ink receiving layer by decomposing a dye with oxygen. This BHT2 spot test relies on yellowing when BHT2 is oxidized to form a stilbenequinone structure, and a correlation is found between the result of the test and the indoor discoloration of the printed image on the ink jet recording material. (For example, refer to Patent Document 14).

  In addition, the proposal includes a preferable coating layer that has little yellowing in the BHT2 spot test, that is, an ink receiving layer containing 0.1% by mass or more of a metal selected from the group of Mg, Ca, Zn, and Ba. Although it is said that the silicon-based pigment is contained in the recording surface, that is, the ink receiving layer, it is described that it has a side effect that the image density is lowered. In order to improve this side effect, it has also been proposed to use a cationic substance in combination, but this time it is stated that the light resistance is reduced, and regarding the problem of storage stability of the image in the inkjet recording sheet, It has been known for some time that a phenolic antioxidant represented by BHT is involved.

  Further, when the BHT transferred to the ink receiving layer turns yellow, the degree varies depending on the material and configuration of the ink jet recording sheet, but is greatly affected by the pigment, colloid particles, and the like constituting the ink receiving layer. This can be seen from what is stated in the above proposal.

  In addition, when the pigment ink as described above is used, there is a problem that the fixability of the image is inferior. In particular, in the latter problem, the pigment ink may be scraped off to the extent that the image portion is lightly touched with a finger, and may not be able to withstand the use for hard copy applications.

  In these proposals, it has been difficult to satisfy excellent printability for both dye ink and pigment ink and yellowing of white paper.

Japanese Patent Publication No. 63-11158 JP 58-94491 A JP 60-67190 A Japanese Patent Laid-Open No. 61-74880 JP-A-7-149037 Japanese Patent Laid-Open No. 9-99630 JP-A-9-267546 Japanese Patent Laid-Open No. 4-201594 Japanese Patent Laid-Open No. 7-32725 JP 2003-285533 A Japanese Patent Laid-Open No. 11-321090 JP 2000-141879 A JP 2001-270219 A JP-A-1-222987

Polymer Degradation and Stability 50 (1995) 313-317 Textile Praxis International October (1980) 1213-1215 Textil Praxis International Marz (1983) 261-264 Textile Chemistand Colorist April (1983) Vol. 15 No4 52-56 Text. Progr. 15 (1987) 16

  The problem of the present invention is that it does not have the disadvantages of the prior art, and a high-definition hard copy obtained by inkjet recording is stored in a closed file, or an adhesive tape is applied to the surface that contacts the inkjet coated surface side during packaging. An object of the present invention is to provide an ink jet recording sheet which is improved in yellowing when it is applied, has no unevenness in printing with dyes and pigment inks, and has excellent ink absorbability and coating layer adhesion.

  As a result of intensive studies in order to solve the above problems, the present inventor has arrived at the present invention. That is, the present invention relates to an inkjet recording sheet having at least one ink receiving layer on a support, wherein the ink receiving layer comprises porous synthetic amorphous silica, malic acid, ammonium chloride, and at least a 5-membered ring amidine. A polymer containing a structural unit or a derivative thereof, and magnesium chloride, wherein the mass ratio of malic acid and magnesium chloride in the ink receiving layer is 60:40 to 40:60 It is.

  Furthermore, the present invention provides a method for producing an ink jet recording sheet having at least one ink receiving layer on a support, comprising porous synthetic amorphous silica, malic acid, ammonium chloride, and at least a 5-membered cyclic amidine structural unit. An ink receiving layer forming coating solution containing a polymer or derivative thereof and magnesium chloride is applied as an ink receiving layer, and the content of malic acid and magnesium chloride in the ink receiving layer forming coating solution The production method is characterized in that the ratio is 60:40 to 40:60.

  The present invention has made it possible to provide an ink jet recording sheet that has little yellowing on blank paper, no printing unevenness with dyes and pigment inks, and excellent ink absorption and coating layer adhesion. If the ink jet recording sheet of the present invention is used, the recording method using any one of dye ink and pigment ink has no blur, high printing density, water resistance of the printed part, uniformity of the printed part, coating Excellent suitability and little yellowing of white paper.

Next, the ink jet recording sheet and the manufacturing method thereof of the present invention will be described in detail. The method for producing an ink jet recording sheet of the present invention comprises a porous synthetic amorphous silica, malic acid, ammonium chloride, a polymer containing at least a 5-membered cyclic amidine structural unit or a derivative thereof, and a chloride. Yellowing, dye, pigment ink absorptivity, and coating layer adhesion are improved by coating and forming an ink receiving layer forming coating solution containing magnesium.
In printing with pigment ink, in order to achieve good solid uniformity, it is advantageous that the mass ratio of malic acid to magnesium chloride is 60:40 to 40:60.

  In the method for producing an ink jet recording sheet of the present invention, a polymer containing porous synthetic amorphous silica, malic acid, ammonium chloride, and at least a 5-membered cyclic amidine structural unit in the ink receiving layer forming coating solution or It is essential to contain the derivative as well as magnesium chloride. Conventionally, the ink-receiving layer-forming coating liquid contains a pigment that enhances ink absorbability. In particular, porous synthetic amorphous silica is used in many inventions as having excellent ink absorbability. However, it is also used in the present invention.

  Wood fibers used in the support of the present invention include chemical pulp such as hardwood bleached kraft pulp (LBKP) and softwood bleached kraft pulp (NBKP), ground pulp, pressurized groundwood pulp, refiner groundwood pulp, thermomechanical pulp ( TMP), mechanical pulp such as chemimechanical pulp, chemiground pulp, and wood pulp such as waste paper pulp such as deinked pulp. In the case of fresh bleached pulp, ECF pulp or TCF pulp is desirable in consideration of the environment. Considering quality aspects such as whiteness, ECF pulp is optimal. In addition, if necessary, they are mixed by using one or more kinds of conventionally known fillers, binders, sizing agents, fixing agents, yield improvers, paper strength enhancers, etc. It can be obtained after forming a web with various paper machines such as a twin wire paper machine and then drying it. In particular, it is desirable to use a support having excellent ink absorbability.

  The structure of the support may be either a single layer or a multilayer, but a multilayer is desirable. In the multilayer structure, it is possible to form an asymmetric structure corresponding to each required characteristic on the surface of the ink receiving layer and the opposite surface (back surface) side. In other words, the chemical composition and pulp type can be changed on the two sides, and if it has a structure of three or more layers, a relatively inexpensive pulp can be applied to the middle layer other than the surface layer. It is advantageous. Moreover, when the pulp used for the middle layer is waste paper pulp, it can be an excellent product as an environmentally friendly product.

  In the present invention, porous synthetic amorphous silica is an essential component for the pigment used in the ink receiving layer forming coating solution, but one or more other known white pigments can also be used. For example, porous inorganic pigments, porous magnesium carbonate, porous alumina and the like are effective because of their large pore volume, but 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, synthetic amorphous silica, colloidal silica, colloidal alumina, pseudoboehmite, aluminum hydroxide, alumina, lithopone, zeolite, Use of white inorganic pigments such as hydrous halloysite, magnesium carbonate, magnesium hydroxide, organic pigments such as styrene plastic pigments, acrylic plastic pigments, polyethylene, microcapsules, urea resins, melamine resins, etc. Kill.

  Examples of the binder include cellulose derivatives such as polyvinyl alcohol, modified polyvinyl alcohol, polyethylene vinyl acetate, hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl pyrrolidone, polyvinyl pyridine, polyacrylamide, polyethylene oxide, polypropylene oxide, starch, and modified starch ( Including physical structure modified biolatex), water soluble binders such as polyacrylic acid, sodium polyacrylate, ethyl polyacrylate, sodium alginate, polystyrene sulfonate sodium, casein, gelatin, terpene, polyethylene, polypropylene, poly Isobutylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl acetal, polymethacrylic acid Chill, polyacrylonitrile, polytetrafluoroethylene, polyvinylidene fluoride, polybutadiene, polyisoprene, polychloroprene, nylon, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyacetal, polybischloromethyloxacyclobutane, polyphenylene oxide, polysulfone, poly- P-xylylene, polyimide, polybenzimidazole, phenol resin, urea resin, melamine resin, epoxy resin, alkyd resin, unsaturated polyester resin, diallyl phthalate resin, styrene-butadiene copolymer, modified styrene-butadiene copolymer, acrylonitrile -Butadiene copolymer, methyl methacrylate-butadiene copolymer, acrylate ester-methacrylic acid ester For example, an emulsion type binder such as a silver copolymer, a vinyl acetate-maleic ester copolymer, a vinyl acetate-acrylic copolymer, an ethylene-vinyl acetate-acrylic copolymer, or a urethane resin binder that is an emulsion type. it can. The degree of polymerization, the degree of saponification, Tg (glass transition temperature), MFT (minimum film-forming temperature), etc. of these binders are not limited. It is also possible to add a crosslinkable functional group in these molecular chains. In addition, two or more kinds of the above-mentioned pigments may be blended and used, and various polymers and monomers may be used not only physically but also chemically combined. In addition to the modification of the functional group, modification by electromagnetic waves (including radiation, light, and sound waves), electric energy, thermal energy, mechanical energy, magnetism, and living organisms may be performed. Furthermore, depending on the purpose, engineering polymers that respond to various energies, biopolymers, ion exchange resins, and the like may be applied as appropriate. The binder is not particularly limited in the synthesis method. However, in the present invention, polyvinyl alcohol and ethylene vinyl acetate resin are preferably used in consideration of ink absorbability and adhesive ability.

  The ink-receiving layer of the ink jet ink of the present invention contains an ink fixing agent in order to improve the fixability and color developability of the ink-jet ink. As the ink fixing agent, a polymer containing at least a 5-membered cyclic amidine structural unit or a derivative thereof is preferable. The mass average molecular weight of this resin is preferably 40,000 to 400,000, in terms of printability and storage stability. If this resin contains a 5-membered ring amidine structural unit, the shape of the polymer and the type of copolymer unit are not particularly limited. The mixing ratio of the ink fixing agent to the paint is about 5.0 to 20.0 parts by mass, more preferably 10.0 to 15.0 parts by mass with respect to 100 parts by mass of the porous synthetic amorphous silica. Good. When the ink fixing agent in the coating liquid is less than 5.0 parts by mass, a sufficient water resistance effect cannot be obtained. Moreover, when it exceeds 20.0 mass parts, the effect of the further water-resistant improvement will not be recognized.

  For image fixability, color tone adjustment, and various quality adjustments, a cationic compound may be mixed and used in addition to a polymer containing a 5-membered cyclic amidine structural unit or a derivative thereof to such an extent that discoloration does not deteriorate.

  The mixing ratio of malic acid in the present invention is about 1.0 to 5.0 parts by mass, more preferably 2.0 to 5.0 parts by mass with respect to 100 parts by mass of porous synthetic amorphous silica. Good. If it is less than 2.0% by mass, the yellowing suppression effect is insufficient. If it exceeds 5.0% by mass, the coating layer strength decreases. Furthermore, other characteristics (print density, ink absorbability) may be adversely affected.

  The mixing ratio of ammonium chloride in the present invention is about 1.0 to 5.0 parts by mass, more preferably 2.0 to 5.0 parts by mass with respect to 100 parts by mass of porous synthetic amorphous silica. Good.

  The mixing ratio of magnesium chloride in the present invention is about 1.0 to 5.0 parts by mass, more preferably 2.0 to 5.0 parts by mass with respect to 100 parts by mass of porous synthetic amorphous silica. Good. If the content is less than 1.0% by mass, the effect on the light resistance and various properties of the image is confirmed, but it is not sufficient. Even if an amount exceeding 5.0% by mass is added, the light resistance and other characteristics are sufficiently improved, but not further improved, the water resistance and moisture resistance are reduced, or the ink is not accepted. There is a possibility that the coating strength of the layer may be impaired. In addition, it becomes difficult to balance the print quality of inkjet recording. These preferable content ranges are preferably 3.0% by mass, and more preferably 3.0 to 4.0% by mass in order to achieve a clear printed image with respect to the pigment.

  In the present invention, for the purpose of fixing the ink to the ink receiving layer, a polymer containing at least a 5-membered cyclic amidine structural unit or a derivative thereof as a cationic ink fixing agent and malic acid, ammonium chloride, water-soluble chloride. Blend with magnesium. Magnesium chloride produces divalent magnesium ions when dissolved in water and ionized. When printing with pigment ink, particularly good solid uniformity is achieved when the mass ratio of malic acid to magnesium chloride in the ink receiving layer is 60:40 to 40:60. In particular, 50:50 is preferable. Beyond this range, the solid uniformity of the pigment ink is inferior.

  As the coating method of the ink receiving layer forming coating liquid of the present invention, air knife coater, roll coater, blade coater, rod coater, bar coater, comma coater, gravure coater, die coater, curtain coater, spray coater, etc. It is possible to employ a method of applying and drying.

  In the method for producing an inkjet recording sheet of the present invention, as contained in the ink-receiving layer-forming coating liquid, as a pigment, an adhesive, a cationic resin, and other additives used for ink absorption, Pigment dispersant, thickener, fluidity improver, surfactant, antifoaming agent, antifoaming agent, mold release agent, foaming agent, penetrating agent, coloring dye, colored pigment, fluorescent whitening agent, UV absorber, Antioxidants, antiseptics, antibacterial agents, water resistance agents, wet paper strength enhancers, dry paper strength enhancers, and the like can be appropriately blended.

The coating amount of the ink receiving layer can be arbitrarily adjusted within the range that covers the surface of the substrate and sufficient ink absorbency is obtained. The work amount is 5 to 20 g / m ² . In particular, it is preferably 8 to 15 g / m ² . If the dry coating amount is less than 5 g / m ² , it is difficult for the coating layer, which is an ink receiving layer, to completely cover the support surface, and the ink absorption by the coating layer is not sufficient. Occur. When the dry coating amount exceeds 20 g / m ² , the adhesive strength between the ink receiving layer and the support becomes a level that cannot be practically used, and peeling of the coating layer from the support, which is called powder falling, occurs. Serious problems arise. Further, an undercoat layer having an ink absorbing layer, adhesiveness, and other functions may be provided between the substrate and the ink receiving layer. Furthermore, a backcoat layer having ink absorbability, writing property, printer suitability, and other various functions may be further provided on the opposite substrate surface provided with the ink receiving layer.

  EXAMPLES Next, although an Example is given and this invention is demonstrated more concretely, this invention is not limited by this. In Examples and Comparative Examples, “parts” and “%” indicate mass parts and mass%, respectively, unless otherwise specified.

<Blank yellowing>
[Adhesive tape test 1]
50 inkjet recording sheets are packaged with wrapping paper. Adhesive tape (CT-15N manufactured by Nichiban Co., Ltd.) is applied to the entire circumference of the wrapping paper. After being left for 1 month at 23 ° C. and 50% RH, the degree of yellowing on the coated surface side, which is the ink-jet ink receiving layer, is evaluated. The degree of yellowing of the coated surface was visually evaluated:
A: There is almost no yellowing of the coated surface.
○: The coating surface is slightly yellowed, but at a practical level.
(Triangle | delta): There exists yellowing of the coating surface and it cannot endure practical use.
X: The coating surface is severely yellowed and cannot be practically used.

[Adhesive tape test 2]
50 inkjet recording sheets are packaged with wrapping paper. Adhesive tape (CT-15N manufactured by Nichiban Co., Ltd.) is applied to the entire circumference of the wrapping paper. After being allowed to stand at 70 ° C. for 1 week, the degree of yellowing on the coated surface side, which is an inkjet ink receiving layer, is evaluated. The degree of yellowing of the coated surface was visually evaluated:
A: There is almost no yellowing of the coated surface.
○: The coating surface is slightly yellowed, but at a practical level.
(Triangle | delta): There exists yellowing of the coating surface and it cannot endure practical use.
X: The coating surface is severely yellowed and cannot be practically used.

<Yellow after printing: Discoloration by offset printing ink>
Using an RI printing tester, 0.6 ml of offset printing ink (TK High Unity SOY Gold Red manufactured by Toyo Ink Manufacturing Co., Ltd.) is printed on the back side of the inkjet recording sheet. The surface printed after 5 minutes and the coated surface that is the ink-jet ink receiving layer were overlapped and allowed to stand at 23 ° C. and 50% RH for 1 week, and then the degree of discoloration of the coated surface was visually evaluated.
A: There is almost no yellowing of the coated surface.
○: The coating surface is slightly yellowed, but at a practical level.
(Triangle | delta): There exists yellowing of the coating surface and it cannot endure practical use.
X: The coating surface is severely yellowed and cannot be practically used.

<Printer printing>
Recording was performed with a PM-A950 manufactured by Epson, which is an ink jet printer for dye ink, and PM-4000PX manufactured by Epson, which is an ink jet printer for pigment ink.

<Print density>
The printing density of the black solid part was measured with a reflection densitometer (RD-19I, manufactured by Gretag Macbeth).

<Bleed>
The bleeding of the printed image was visually evaluated.
A: There is almost no bleeding in the mixed color printing portion, and the characters can be read very clearly.
○: There is little blurring of the mixed color printing portion, characters can be read clearly, and it is at a practical level.
Δ: Slight blurring of the mixed color printing portion, slightly difficult to read characters, unusable for practical use.
X: The mixed color printing portion is blurred, characters are difficult to read, and cannot be practically used.

<Water resistance>
The water resistance of the printed image was evaluated.
A: Excellent.
○: Slightly superior (practical level).
Δ: Normal (practical tolerance level).
X: Inferior (not practical)

<Uniformity>
The uniformity of the solid part was evaluated.
A: Excellent.
○: Slightly superior (practical level).
Δ: Normal (practical tolerance level).
X: Inferior (not practical)

<Light resistance>
Atlas weather meter manufactured by Toyo Seiki Co., Ltd. Xenon lamp 340 nm 0.50 W / m ² 40 ° C. Black panel temperature 60 ° C., 50% RH 24 hours irradiation. The degree of decrease in print density was visually observed.
A: Excellent.
○: Slightly superior (practical level).
Δ: Normal (practical tolerance level).
X: Inferior (not practical)

<Gakushin style friction fastness>
As a sample for Gakushin friction fastness, the coated surface, which is an ink-jet ink receiving layer, and black colored paper with excellent surface strength (trade name: Yayoi Color Paper, manufactured by Hokuetsu Kishu Paper Co., Ltd.) are in close contact with each other, and Gakushin friction fastness is obtained. The degree of powder removal by 20 reciprocating frictions was visually observed with a degree tester under a load of 300 g.
A: Excellent.
○: Slightly superior (practical level).
Δ: Normal (practical tolerance level).
X: Inferior (not practical)

<RI printing strength>
Using an RI printing tester, With the offset printing ink of V = 15, the surface strength of the coated surface, which is an inkjet ink receiving layer, was measured. The rubber blanket stain and the stain were transferred to a gloss type A2 coat (trade name: μ coat, manufactured by Hokuetsu Kishu Paper Co., Ltd.) excellent in offset printability, and evaluated together with the transfer pattern.
A: Excellent.
○: Slightly superior (practical level).
Δ: Normal (practical tolerance level).
X: Inferior (not practical)

Next, examples and comparative examples relating to the ink jet recording sheet of the present invention are shown.

<Production of support>
The mass ratio of 100 parts of LBKP (freeness 550 ml: Canadian standard freeness), talc (trade name: Tlite 83, manufactured by Taihei Talc) and kaolin (trade name: Hydra Sparse, manufactured by Seal Kaolin) 5 parts of 1: 1 pigment, 3 parts of sulfuric acid band, 0.25 part of rosin sizing agent (trade name: AL-120, manufactured by Seiko PMC), and cationized starch (trade name: Mermaid C-50, Shikishima) After adding 1.0 parts of Starch Co., Ltd., making paper with a long paper machine, and further using a size press machine with oxidized starch (trade name: Oji Ace A, made by Oji Corn Starch Co., Ltd.) double-side coated to a 1.0 g / ^{m 2,} then the specific volume at machine calender performs calendered so that 1.2 cm ³ / g, to obtain a support having a basis weight of 100 g / ^{m 2.}

<Composition of ink receiving layer coating liquid>
100 parts of porous synthetic amorphous silica (trade name: Silojet P409, manufactured by Grace)
15.0 parts of polyvinyl alcohol (trade name: PVA-117, manufactured by Kuraray Co., Ltd.)
3.0 parts of malic acid (trade name: Fuso malate, manufactured by Fuso Chemical Co., Ltd.)
3.0 parts of ammonium chloride (trade name: ammonium chloride, manufactured by Toshin Chemical Co., Ltd.)
Magnesium chloride (trade name: Magrand, manufactured by Ako Kasei Co., Ltd., used in anhydrous magnesium chloride) 3.0 parts,
30.0 parts of polyethylene vinyl acetate (trade name: Polysol EVA AD-10, Showa High Polymer Co., Ltd.),
15.0 parts of an ink fixing agent (acrylamide / acrylonitrile / N-vinylacrylamidine hydrochloride / N-vinylformamide copolymer having a 5-membered ring amidine structure: trade name: SC700L, manufactured by Hymo) were added and stirred, Further, water was added to obtain a coating solution having a solid content concentration of 20%.

On one side of the obtained support, the ink receiving layer coating solution is applied with an air knife coater so that the dry coating amount is 10 g / m ² , so that the water content becomes 6.5%. Then, the surface was smoothed using a calendar.

  An ink jet recording sheet was obtained in the same manner as in Example 1 except that 3.5 parts of malic acid and 2.5 parts of ammonium chloride in the ink receiving layer coating liquid of Example 1 were used.

  An ink jet recording sheet was obtained in the same manner as in Example 1, except that 2.5 parts of malic acid and 3.5 parts of ammonium chloride in the ink receiving layer coating liquid of Example 1 were used.

  An ink jet recording sheet was obtained in the same manner as in Example 1 except that malic acid in the ink receiving layer coating solution of Example 1 was 4.5 parts and ammonium chloride was 5.0 parts.

  An ink jet recording sheet was obtained in the same manner as in Example 1 except that 2.0 parts of magnesium chloride in the ink receiving layer coating solution of Example 1 was used.

<Comparative Example 1>
An ink jet recording sheet was obtained in the same manner as in Example 1 except that ammonium chloride and magnesium chloride in Example 1 were omitted.

<Comparative Example 2>
An ink jet recording sheet was obtained in the same manner as in Example 1 except that malic acid and magnesium chloride in Example 1 were omitted.

<Comparative Example 3>
An ink jet recording sheet was obtained in the same manner as in Example 1 except that malic acid and ammonium chloride in Example 1 were omitted.

<Comparative Example 4>
An ink jet recording sheet was obtained in the same manner as in Example 1 except that malic acid in Example 1 was changed to 5.0 parts, ammonium chloride was changed to 2.0 parts, and magnesium chloride was changed to 3.0 parts.

<Comparative Example 5>
An ink jet recording sheet was obtained in the same manner as in Example 1 except that malic acid in Example 1 was changed to 2.0 parts, ammonium chloride was changed to 4.0 parts, and magnesium chloride was changed to 5.0 parts.

<Comparative Example 6>
An ink jet recording sheet was obtained in the same manner as in Example 1 except that malic acid in Example 1 was changed to 6.0 parts, ammonium chloride was changed to 3.0 parts, and magnesium chloride was changed to 0 part.

<Comparative Example 7>
An ink jet recording sheet was obtained in the same manner as in Example 1 except that 3.0 parts of malic acid, 6.0 parts of ammonium chloride, and 0 parts of magnesium chloride were changed.

<Comparative Example 8>
An ink jet recording sheet was obtained in the same manner as in Example 1 except that the ink fixing agent of Example 1 was changed to (cationic acrylamide-diallylamine salt copolymer, trade name: SR1001, manufactured by Sumitomo Chemical Co., Ltd.).

<Comparative Example 9>
An ink jet recording sheet was obtained in the same manner as in Example 1 except that the ink fixing agent of Example 1 was changed to (polyallylamine trade name: PAA-15C, manufactured by Nittobo Co., Ltd.).

  As is clear from the above results, the ink jet recording sheet obtained in the examples according to the present invention can be stored by closing a high-definition hard copy obtained by ink jet recording in a file, or at the time of packaging. The yellowing that occurs when an adhesive tape is applied to the surface in contact with the side is improved, there is no printing unevenness with dyes and pigment inks, and the ink absorbability and coating layer adhesion are excellent. In the case of Comparative Examples 4 and 5 in which the mass ratio of malic acid to magnesium chloride is out of the range of 60:40 to 40:60, a blank yellowing phenomenon is observed, and the print density when pigment ink is used. Not only was C low, but in the case of Comparative Example 4 with excessive malic acid, bleeding was significant.

Claims (3)

Porous synthetic amorphous silica, malic acid, ammonium chloride, a polymer containing at least a 5-membered cyclic amidine structural unit or a derivative thereof, and magnesium chloride, and a mass ratio of malic acid to magnesium chloride of 60 : 40-40: 60, The ink receiving layer forming coating liquid for inkjet recording sheets characterized by the above-mentioned. In the ink jet recording sheet having an ink-receiving layer of at least one layer on a support, the ink receiving layer of the at least one layer, porous synthetic amorphous silica, malic acid, ammonium chloride, and at least 5-membered ring amidine structures A polymer containing a unit or a derivative thereof, and all of magnesium chloride are contained, and a content mass ratio of malic acid and magnesium chloride in the ink receiving layer is 60:40 to 40:60. Inkjet recording sheet.   In a method for producing an ink jet recording sheet having at least one ink receiving layer on a support, a polymer containing porous synthetic amorphous silica, malic acid, ammonium chloride, and at least a 5-membered cyclic amidine structural unit, or a polymer thereof A coating liquid for forming an ink receiving layer containing a derivative and magnesium chloride is applied as an ink receiving layer, and the content ratio of malic acid to magnesium chloride in the coating liquid for forming an ink receiving layer is set to 60:40. 40:60, The manufacturing method of the inkjet recording sheet characterized by the above-mentioned.