JP2006272939A - Method for producing ink jet recording sheet - Google Patents

Abstract

A method for producing an ink jet recording sheet having very high printing density and water resistance, excellent ink absorbability, and capable of obtaining image clarity comparable to silver salt photographic printing paper is provided.
An ink absorbing layer comprising at least one layer is provided on a gas-permeable support, and a gloss developing layer containing aluminum oxide or alumina hydrate is provided on the ink absorbing layer. In the method for producing an ink jet recording sheet, which is solidified using a coagulation liquid and pressed into a heated mirror surface roll and dried while it is in a wet state, the gloss developing layer is solidified and then applied to the gloss developing layer. Forms a pool of nip water at the press nip where the nip water is applied and presses against the mirror surface roll. An aqueous liquid containing a cationic substance is applied.
[Selection figure] None

Description

  The present invention relates to a method for producing an ink jet recording sheet having image clarity comparable to silver salt photographic printing paper, excellent ink absorbability, and high print density and water resistance.

  The ink jet recording system records images, characters, and the like by flying fine ink droplets according to various operating principles and attaching them to a recording sheet such as paper. The recording system has features such as high speed, low noise, easy multi-coloring, large flexibility of recording patterns, no need for development and fixing, and various uses as a printing device for various character graphics and color images. Is rapidly spreading. Furthermore, according to multicolor ink jet printing, it is possible to obtain a printed material that is comparable to silver salt color photographic printing, and the equipment required for printing is small and inexpensive. The ink jet recording method has been widely applied to the field of full-color image printing. Accordingly, an ink jet recording sheet having a high surface gloss has been strongly demanded from the conventional matte tone.

  As a method for imparting surface gloss to an ink jet recording medium, a method of smoothing the surface of a coating layer by using a calendar device such as a super calender or gloss calender and passing paper between rolls under pressure or temperature is generally used. It is. However, for the purpose of imparting surface gloss to the ink jet recording medium, calendering under high linear pressure improves the surface gloss, but the voids in the coating layer are reduced, leading to deterioration of ink absorbency. Become. Therefore, at present, it is difficult to satisfy the contradictory properties of surface gloss and ink absorbency by calendering.

  As a method for imparting surface gloss without using calendar treatment, a method for producing a high-gloss coated sheet for printing generally called cast-coated paper (hereinafter abbreviated as cast treatment) is known. This casting method includes a direct method in which the wet coating layer is pressed against a heated mirror roll, and the wet coating layer is dried once and then plasticized by re-wetting so as to be pressed against the mirror roll. A wet method and a solidification method in which a wet coating layer is solidified and pressed against a mirror-finished surface are known, and a method for producing an inkjet recording sheet by a casting method has already been proposed (for example, Patent Document 1). , Patent Document 2 and Patent Document 3).

  Among these casting methods, the direct method is such that when the wet coating layer is pressed against the mirror roll, the water in the paint boils suddenly and destroys the coating layer. There is a problem that it is impossible to make it low speed operation. Also, in the rewet method, the degree of plasticization is low compared to other methods in order to rewet the once dried coating layer, and therefore the rewet coated layer adheres uniformly to the mirror roll. In order to solve these problems, there is a problem that the coated surface is inferior in homogeneity, and in order to solve these problems, manufacture of ink jet cast coated paper that forms a pool of nip water in the press nip with the mirror surface A method has been proposed (see Patent Document 4).

  On the other hand, in the solidification method, the coating layer is pressed and dried to the mirror-finished surface in a plasticized solidified state without drying and solidifying the coating layer like the rewet method. can do. Further, even if the temperature of the mirror surface roll is increased, the coating layer is not destroyed. Furthermore, since a bulky and porous coating layer can be formed, it is suitable as a method for producing an ink jet recording sheet among the casting methods.

  Various proposals have been made in order to obtain an ink jet recording sheet excellent in surface gloss using a coagulation method. For example, a combination of a resin in the coating layer and a coagulant capable of coagulating the resin (see, for example, Patent Document 5, Patent Document 6, Patent Document 7, and Patent Document 8), and a gloss-expressing substance in the coagulation liquid It can be included (for example, see Patent Document 9).

  Although the surface gloss can be obtained as it is by the casting method, it is an index called image clarity as well as the surface gloss that determines the aesthetic element of the gloss. The image clarity is an index of how clear and undistorted the image is when an object is reflected on a glossy surface. Even with the same surface gloss, it can be said that a higher gloss level is perceived as there is no distortion, and the aesthetic element is higher. However, an evaluation that correlates with visual sensation cannot be made only by measuring the surface gloss level. It is hard to say that satisfactory image clarity can be obtained with conventional techniques.

In recent years, a glossy inkjet recording sheet having a higher printing density has been demanded. In order to obtain an ink jet recording sheet having high image clarity and high printing density, it is known that alumina particles having a small primary particle size and high transparency are used as the pigment of the cast coating liquid. It is hard to say that sufficient print density is obtained. In order to increase the printing density of an ink jet recording sheet, a method of fixing ink jet ink near the surface of a coating layer by introducing a cationic substance into the coating layer is generally known. However, in a cast coating solution using alumina as a pigment, a cationic substance is poorly miscible with alumina and causes thickening and aggregation. Therefore, it is difficult to obtain a uniform glossy surface.
Japanese Patent Publication No. 6-94229 Japanese Patent No. 2750534 Japanese Patent Publication No.8-1038 Japanese Patent Laid-Open No. 8-300804 JP-A-9-59897 JP 2002-266282 A JP 2002-283597 A JP 2002-293004 A JP 2002-166645 A

  An object of the present invention is to provide a method for producing an ink jet recording sheet having very high printing density and water resistance, excellent ink absorbability, and capable of obtaining image clarity comparable to silver salt photographic printing paper. It is in.

  An ink-absorbing layer consisting of at least one layer is provided on a gas-permeable support, and a gloss-expressing layer containing aluminum oxide or alumina hydrate is provided on the ink-absorbing layer. In the method of manufacturing an inkjet recording sheet, which is pressed and dried on a heated mirror roll while it is in a wet state, the glossy layer is solidified and then nip water is applied to the glossy layer. In the press nip portion that is pressed against the mirror surface roll, a nip water pool is formed, and the water-soluble cationic substance is applied on the gloss development layer after the gloss development layer is formed until it is pressed against the mirror roll. This was achieved by applying an aqueous liquid containing.

  In the present invention, it is preferable that the aqueous liquid containing the water-soluble cationic substance is applied as a coagulating liquid or applied as nip water during the coagulation treatment.

  According to the present invention, it is possible to provide a method for producing an ink jet recording sheet having a very high printing density, excellent ink absorbability, and image clarity comparable to silver salt photographic printing paper.

  Hereinafter, the method for producing an ink jet recording sheet of the present invention will be described in detail. In the present invention, the gloss developing layer is subjected to a coagulation method. The coagulation method is a treatment method in which the glossy expression layer coated on the ink absorption layer is gelled by being treated with a coagulation liquid when it has fluidity. Pressed against the mirror-finished roll and dried.

  In the present invention, nip water is applied onto the gelled gloss developing layer, and a pool of nip water is formed in the press nip portion that is pressed against the mirror roll. The nip water is a liquid that is applied to increase the adhesion between the glossy expression layer that has been gelated by the coagulation treatment and the mirror roll. The nip water is not particularly limited, and for example, water alone or a product obtained by adding various chemicals to water may be used.

  The method for applying the nip water is not particularly limited as long as it can be applied on the glossy layer, and can be appropriately selected from known methods (for example, a roll method, a spray method, a curtain method, etc.).

  The glossy layer of the present invention contains at least one of aluminum oxide (gas phase method alumina, δ-alumina, θ-alumina, γ-alumina) and alumina hydrate (boehmite, pseudoboehmite) as inorganic fine particles. . In particular, alumina hydrate having a pseudo boehmite structure is preferable because the average particle size is extremely small and high image clarity is obtained, and the transparency of the glossy layer is improved and the print density is increased.

  The image clarity referred to in the present invention is a measure of how sharp and undistorted an image is projected when an object is reflected on a glossy surface, using an optical device defined in JIS H8686, The image definition (C) is obtained from the light intensity waveform obtained through the optical comb. There are various types of optical combs having a dark part bright part ratio of 1: 1 and a width of 0.125, 0.5, 1.0 and 2.0 mm. In the measurement, the optical comb is moved, the highest waveform (M) and the lowest waveform (m) on the recording paper are read, and the image definition is obtained as C = (M−m) / (M + m) × 100. The image clarity C is an index indicating that the image clarity is good when the value is large, and “blur” or “distortion” is present when the value is small. It has been found that if this “blurring” or “distortion” is small, the visual glossiness is improved even when the gloss value on the gloss meter is the same.

  In the glossy layer of the present invention, a conventionally used pigment may be used in combination as appropriate. For example, light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, aluminum hydroxide and other inorganic pigments, styrenic plastic pigments, Examples thereof include organic plastic pigments such as acrylic plastic pigments, polyethylene, microcapsules, urea resins, and melamine resins.

  The glossy layer of the present invention preferably contains a binder. Examples of the binder include natural resins such as casein, gelatin, and soy protein, starch derivatives such as etherified starch and phosphate esterified starch, cellulose derivatives such as carboxycellulose and hydroxyethylcellulose, and various saponification degrees. Various derivatives such as polyvinyl alcohol or its silanol-modified products, carboxyl-modified products, cation-modified products, acetoacetyl-modified products, water-soluble adhesives such as thermosetting synthetic resins such as melamine resins and urea resins, polyethylene glycol, polyacrylamide, etc. Examples thereof include water-soluble resins, and styrene-acrylic, acrylic acid and methacrylic acid ester, polyurethane water-soluble resins or synthetic resin emulsions. At least one of these can be selected and used.

  The content of the binder in the glossy layer is preferably 5 to 40% by mass with respect to the pigment component, because good coating layer strength and ink absorbability can be obtained. More preferably, it is 10-30 mass%.

  Furthermore, as additives, pigment dispersants, thickeners, fluidity improvers, viscosity stabilizers, pH adjusters, surfactants, antifoaming agents, antifoaming agents, mold release agents, foaming agents, penetrating agents, coloring Dyes, coloring pigments, fluorescent brighteners, ultraviolet absorbers, antioxidants, leveling agents, preservatives, antibacterial agents, water-proofing agents, and the like can be appropriately added within a range that does not impair the object of the present invention.

  For the application of the gloss developing layer, for example, various devices such as various blade coaters, roll coaters, air knife coaters, bar coaters, rod blade coaters, comma coaters, lip coaters, curtain coaters, short dwell coaters, and size presses may be used. it can.

When the dry coating amount of the glossy layer is 5 to 30 g / m ² , high image clarity and ink absorbability are obtained, which is preferable. More preferably, it is 5-20 g / m < ² >.

  In the present invention, an aqueous liquid containing a water-soluble cationic substance is applied on the glossy expression layer after the glossy expression layer is provided until it is pressed against the mirror roll. Thereby, since the water-soluble cationic substance is unevenly distributed on the surface of the gloss developing layer, the ink jet ink can be effectively fixed on the surface of the gloss developing layer, and the print density is increased.

  The application method of the aqueous liquid containing the water-soluble cationic substance is not particularly limited as long as it can be applied to the glossy layer, and is appropriately selected from known methods (for example, roll method, spray method, curtain method, etc.). Can be used.

  As the water-soluble cationic substance, any of a monomer, an oligomer, and a polymer can be applied. As the polymer, polyalkylene polyamide, polyalkylene polyurea, polyamide polyurea, polyamino epoxy resin, or a reaction product of these with an aldehyde. Reaction products with alkylating agents, ring-opening polymers of ethyleneimine, homopolymers of cationic vinyl polymers or copolymers with other polymerizable monomers, homopolymers of N-vinylamide monomers or other Copolymerized with a polymerizable monomer, a Mannich reaction product obtained by reacting ammonia, primary amine, secondary amine and formaldehyde with a polymer having active hydrogen, a reaction product of a polymer having active hydrogen and a cationizing agent, activity Polymers with hydrogen and ammonia, amines, epihalohydrins Reaction product, chitosan hydrolyzed chitin, polymer having active hydrogen and any of the above-described polymers reacted with a crosslinking agent such as aldehyde, epihalohydrin, polyisocyanate, inorganic aluminum-containing aluminum Examples include basic polyaluminum hydroxide compounds that are cationic polymers. These water-soluble cationic substances may be used alone or in combination of two or more. Among these water-soluble cationic substances, those that cause aggregation with the aluminum oxide or aluminum hydrate in the glossy layer may be used as a coagulant in the coagulation liquid.

  The content of the water-soluble cationic substance in the aqueous liquid containing the water-soluble cationic substance is preferably 1 to 5% by mass. If the amount is less than 1% by mass, the effect of increasing the print density may not be sufficiently exhibited. If the amount exceeds 5% by mass, the ink absorbability may be lowered or the releasability from the heated mirror roll may be deteriorated. is there.

  The aqueous liquid containing the water-soluble cationic substance is preferably applied as a coagulation liquid used in the coagulation treatment. Moreover, you may provide the aqueous liquid containing the said water-soluble cationic substance as said nip water after coagulating the said gloss expression layer. Examples of methods for applying the coagulating liquid and nip water include, but are not limited to, a roll method, a spray method, a curtain method, and the like.

  In the present invention, when the aqueous liquid containing the water-soluble cationic substance is applied as a coagulation liquid, if the water-soluble cationic substance alone does not have sufficient coagulation power for the glossy layer, the water-soluble cation is used. The aqueous liquid containing the active substance may be used in combination with a coagulant. Various metal salts with calcium, zinc, barium, lead, magnesium, cadmium, aluminum such as formic acid, acetic acid, citric acid, tartaric acid, lactic acid, hydrochloric acid, nitric acid, phosphoric acid, malic acid, acrylic acid, etc. And ammonium salts, boric acid, borates, borax, and the like, and calcium formate and boric acid are preferred as substances that do not cause aggregation and precipitation with the water-soluble cationic substance. The concentration of the coagulant used in combination depends on the concentration of the water-soluble cationic substance in the aqueous liquid containing the water-soluble cationic substance, but is preferably in the range of 0.5 to 6% by mass of the coagulation liquid in terms of anhydride, More preferably, it is 1-5 mass%.

  In the present invention, when the aqueous liquid containing the water-soluble cationic substance is applied as nip water, the glossy layer is coagulated with a coagulating liquid. The coagulation liquid contains a coagulant, formic acid, acetic acid, citric acid, tartaric acid, lactic acid, hydrochloric acid, nitric acid, phosphoric acid, malic acid, acrylic acid and other calcium, zinc, barium, lead, magnesium, cadmium, aluminum, etc. Various metal salts and ammonium salts, boric acid, borates, borax and the like can be mentioned, and one or more can be selected and used. The concentration of the coagulant in the coagulation liquid is preferably in the range of 0.5 to 6% by mass in terms of anhydride, more preferably 1 to 5% by mass.

  In the coagulation liquid, as additives, for example, dye fixing agents (various cationic substances), mold release agents, water retention agents, thickeners, antifoaming agents, preservatives, coloring agents, water resistance agents, wetting agents, Known auxiliaries such as plasticizers, fluorescent dyes, ultraviolet absorbers and antioxidants can be appropriately added.

In the present invention, the ink absorbing layer preferably contains a pigment. For example, synthetic amorphous silica, light calcium carbonate, heavy calcium carbonate, kaolin, calcined 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 silica, colloidal alumina, pseudoboehmite, aluminum hydroxide, alumina, lithopone, zeolite, hydrous halloysite, magnesium carbonate, magnesium hydroxide, white inorganic pigments, styrene plastic pigment, acrylic plastic pigment And organic pigments such as polyethylene, microcapsules, and melamine resins, and synthetic amorphous silica having a large pore volume is particularly preferable. Such synthetic amorphous silica is porous, amorphous fine particles in which a three-dimensional structure of SiO ₂ is formed by gelation of silicic acid, and has a pore diameter of about 1 to ₂₀₀ nm.

  As such synthetic amorphous silica, commercially available products can be suitably used. For example, Mizukacil P-526, Mizukacil P-801, Mizukacil NP-8, Mizukacil P-802, Mizukacil P-802Y, Mizukacil C -212, Mizukacil P-73, Mizukacil P-78A, Mizukacil P-78D, Mizukacil P-78F, Mizukacil P-87, Mizukacil P-705, Mizukacil P-707, Mizukacil P-707D, Mizukacil P-709, Mizukacil C -402, Mizukasil C-484 (Mizawa Chemical Co., Ltd.), Toxeal U, Toxeal UR, Toxeal GU, Toxeal AL-1, Toxeal GU-N, Toxeal N, Toxeal NR, Toxeal PR, Sorex, Fineseal E -50, fine seal T-32, INSEAL X-37, FINE SEAL X-37B, FINE SEAL X-60, FINE SEAL X-70, FINE SEAL RX-70, FINE SEAL A, FINE SEAL B (above, manufactured by Tokuyama), Carplex FPS-101, Carplex CS-7, Carplex 80, Carplex XR, Carplex 67 (manufactured by Shionogi & Co., Ltd.), Nipgel AY-420, Nipgel AY-601, Nipgel AY-603, Nipgel AZ-600, Nipgel BY-400 Nip gel BY-001, nip gel G-0123, nip gel G-0124, nip sill VN3, nip sill LP, nip sill ER, nip sill NA, nip sill E-200A (above, manufactured by Tosoh Silica), siricia 770, siricia 40, Cylicia 730, Cylicia 440, Cylicia 431, Cylicia 450, Cylicia 470, Cylicia 250, Cylicia 310, Cylicia 350, Cylicia 320 (manufactured by Fuji Silicia Chemical), Cyloid AL-1, Cyloid AL-1B, Cyloid CP4, Thyroid 72W, Thyroid ED3, Thyroid 74, Thyroid 74X6500, Thyroid 74X5500, Thyroid 74X4500, Thyroid 622, Thylojet P405, Thylojet P407, Thylojet P409, Thylojet P412, Thyrojet P416, Thylojet P616 (above, made by Grace) Etc.

  The ink absorbing layer preferably contains a binder. Examples of the binder include various derivatives such as polyvinyl alcohol or its silanol-modified product, carboxylated product, cationized product, acetoacetylated product, conjugated diene copolymer such as styrene-butadiene copolymer and methyl methacrylate-butadiene copolymer. Unitary latex, acrylic polymer latex such as polymer or copolymer of acrylic ester and methacrylic ester, vinyl polymer latex such as ethylene-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer, or These include functional group-modified polymer latexes and polyurethane resin latexes based on functional group-containing monomers such as carboxy groups of these various polymers. Among these, silanol-modified polyvinyl alcohol, ethylene-vinyl acetate copolymer latex, and styrene-butadiene copolymer latex are preferable, and at least one of these can be selected and used.

  The binder content in the ink absorbing layer is preferably from 5 to 70% by mass with respect to the pigment, since good coating layer strength and ink absorptivity are obtained. More preferably, it is 10-60 mass%.

  Furthermore, in the ink absorption layer, as an additive, a dye fixing agent (various cationic substances), a pigment dispersant, a thickener, a fluidity improver, an antifoaming agent, an antifoaming agent, a release agent, a sizing agent, A penetrating agent, a coloring dye, a coloring pigment, a fluorescent brightening agent, an ultraviolet absorber, an antioxidant, an antiseptic, a baitproofing agent, a wet strength enhancer, a dry strength enhancer, and the like can be appropriately blended.

When the dry coating amount of the ink absorbing layer is 5 to 25 g / m ² , good ink absorbability and surface quality are obtained, which is preferable. More preferably, it is 5-20 g / m < ² >. Further, the ink absorbing layer can be applied by dividing a certain coating amount into several times.

  Various methods such as blade coater, roll coater, air knife coater, comma coater, bar coater, rod blade coater, curtain coater, short dwell coater, size press, etc. can be applied on-machine or off-machine. Can be used. Coating by a curtain coater is particularly preferred because a coating layer having a uniform thickness with no coating unevenness can be obtained.

  After application of the ink absorbing layer, the back surface may be sprayed with humidified air or humidified steam to correct the curl, and further, a calendar process using a machine calendar, a TG calendar, a super calendar, a soft calendar, or the like may be performed. .

The support used in the present invention is a gas-permeable support, and a known paper support can be appropriately selected and used. For example, wood pulp such as chemical pulp such as LBKP and NBKP, mechanical pulp such as GP, PGW, RMP, TMP, CTMP, CMP, and CGP, waste paper pulp such as DIP, and conventionally known pigments as a main component, binder and Various types of equipment such as long net paper machine, circular net paper machine, twin wire paper machine, etc. are mixed using one or more additives such as sizing agent, fixing agent, yield improver, cationizing agent, paper strength enhancer, etc. And a base paper provided with a size press or an anchor coat layer of starch, polyvinyl alcohol or the like on the base paper. The basis weight of the support is usually 40 to 300 g / m ² , but is not particularly limited.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. In the examples and comparative examples, “parts” and “%” indicate parts by mass and mass% unless otherwise specified. In addition, the number of parts shown in the blend is the number of substantial components. Moreover, the particle diameter shown in an Example and a comparative example is an average particle diameter calculated | required by the dynamic light scattering method. The cast coater was operated at the maximum speed at which no uneven gloss occurred.

A mixture of 50 parts of hardwood bleached kraft pulp (LBKP, whiteness 90%) and 50 parts of softwood bleached sulfite pulp (NBSP, whiteness 90%) was beaten to 350 ml with Canadian Standard Freeness to prepare a pulp slurry. Add 6 parts of talc as a filler, 0.5 part of alkyl ketene dimer as a sizing agent, 1.0 part of polyacrylamide and 2.0 parts of cationized starch as a dry paper strength enhancer, and dilute with water to make a 1% slurry. It was. This slurry was made with a long paper machine so as to have a basis weight of 150 g / m ² to prepare a support. On one surface of this support, coating liquid a as an ink absorbing layer was coated and dried by an air knife coater so that the coating amount after drying was 10 g / m ² . On the ink absorbing layer thus obtained, the glossy layer coating liquid b is applied using an air knife coater so that the coating amount after drying is 10 g / m ^2, and the coated surface has fluidity. After the coagulating liquid c is applied and sprayed, the nip water d is applied on the gelled coated surface by the spray system to form a nip water pool in the press nip portion that is pressed against the mirror roll. However, the ink jet recording sheet of the present invention was obtained by casting by a solidification method in which the film was pressed against a mirror roll heated to 100 ° C. and dried.

<Ink absorbing layer coating solution a>
100 parts of synthetic amorphous silica (Syloid ED5; oil absorption 300 ml / 100 g, manufactured by Grace), 20 parts of silanol-modified polyvinyl alcohol (R-1130, manufactured by Kuraray), styrene-butadiene copolymer latex (Luckster DS226, Dai Nippon Ink Chemical Co., Ltd.) 10 parts, Cationic Dye Fixing Agent (Smiles Resin 1001, Sumitomo Chemical Co., Ltd.) 10 parts blended in water, uniformly dispersed and coated with an ink absorption layer having a solid content concentration of 18% A working fluid a was prepared.

<Glossy layer coating liquid b>
30 parts of cationized colloidal silica (Snowtex-AK, manufactured by Nissan Chemical Industries), 70 parts of alumina hydrate with a pseudoboehmite structure and an average particle size of 50 nm, cationic acrylic resin emulsion (glass transition temperature 60 ° C.) ) 10 parts, 10 parts of polyvinyl alcohol (PVA117, manufactured by Kuraray Co., Ltd.) and 3 parts of a release agent (nonionic oleic acid emulsion) are mixed and uniformly dispersed to obtain a glossy layer coating liquid b having a solid content concentration of 20%. Was prepared.

<Preparation of coagulation liquid c>
A coagulation liquid c containing a coagulant (calcium formate (anhydrous equivalent)) with a solid content of 4% and a water-soluble cationic substance (Himax SC-700, manufactured by Hymo Co., Ltd.) with a solid content of 2% was prepared.

<Nip water d>
Nip water was water.

  In the coagulation liquid c, except that the water-soluble cationic substance (Himax SC-700, manufactured by Hymo Co.) was changed to a water-soluble cationic substance (Smileze Resin 1001, manufactured by Sumitomo Chemical Co., Ltd.) with a solid content concentration of 2%, The ink jet recording sheet of the present invention was obtained in the same manner as in Example 1.

  In the coagulation liquid c, the same procedure as in Example 1 was carried out except that the coagulant (calcium formate) was not added and the water-soluble cationic substance (Himax SC-700, manufactured by Hymo) had a solid content concentration of 4%. An ink jet recording sheet of the invention was obtained.

  In the coagulation liquid c, a water-soluble cationic substance (Himax SC-700, manufactured by Hymo) is not added, and the water-soluble cationic substance (Himax SC-700, manufactured by Hymo) has a solid content concentration as nip water d. An ink jet recording sheet of the present invention was obtained in the same manner as in Example 1 except that the content was 1%.

  An ink jet recording sheet of the present invention was obtained in the same manner as in Example 4 except that the nip water d was a water-soluble cationic substance (Smileze Resin 1001, manufactured by Sumitomo Chemical Co., Ltd.) with a solid content concentration of 1%.

  An ink jet recording sheet of the present invention was obtained in the same manner as in Example 4 except that the water-soluble cationic substance (Purachem WT, manufactured by Riken Green Co., Ltd.) was used as the nip water d at a solid content concentration of 1%.

  An ink jet recording sheet of the present invention was obtained in the same manner as in Example 1 except that the nip water d was a water-soluble cationic substance (Smileze Resin 1001, manufactured by Sumitomo Chemical Co., Ltd.) with a solid content concentration of 1%.

  An ink jet recording sheet of the present invention was obtained in the same manner as in Example 2 except that the nip water d was a water-soluble cationic substance (Himax SC-700, manufactured by Hymo Co., Ltd.) with a solid content concentration of 1%.

  In the coagulation liquid c, Example 1 except that the coagulant (boric acid (anhydride equivalent)) solid content concentration was 3% and the water-soluble cationic substance (Himax SC-700, manufactured by Hymo Co., Ltd.) solid content concentration was 2%. In the same manner, an ink jet recording sheet of the present invention was obtained.

(Comparative Example 1)
An ink jet recording sheet was obtained in the same manner as in Example 1 except that the water-soluble cationic substance (Himax SC-700, manufactured by Hymo Co.) was not added to the coagulating liquid c.

(Comparative Example 2)
An ink jet recording sheet was obtained in the same manner as in Example 9 except that the water-soluble cationic substance (Himax SC-700, manufactured by Hymo Co.) was not added to the coagulation liquid c.

(Comparative Example 3)
An ink jet recording sheet was obtained in the same manner as in Example 1 except that no nip water d was applied and no liquid pool of nip water was formed in the press nip portion pressed against the mirror surface roll.

(Comparative Example 4)
An ink jet recording sheet was obtained in the same manner as in Example 9 except that no nip water d was applied and no nip water pool was formed in the press nip portion pressed against the mirror roll.

(Comparative Example 5)
After an inkjet recording sheet was prepared in the same manner as in Comparative Example 1, a water-soluble cationic substance (Himax SC-700, manufactured by Hymo Co.) aqueous solution (solid content concentration 2%) was applied to the glossy surface of the inkjet recording sheet. The ink-jet recording sheet was obtained by coating and drying with an air knife coater such that the coating amount after drying was 0.5 g / m ² .

  As described above, the ink jet recording sheets prepared in Examples and Comparative Examples were evaluated by the following evaluation methods, and the results are summarized in Table 1.

<Image clarity>
The image definition (C) defined by JIS H8686 was used. Using an image clarity measuring device (ICM-1DP manufactured by Suga Test Instruments Co., Ltd.), using an optical comb having a width of 2.0 mm, reading the maximum waveform (M) and the minimum waveform (m) at a reflection angle of 60 degrees, C = The image definition was determined as (M−m) / (M + m) × 100. When the image clarity of image clarity is 65% or more, the glossiness of appearance is high, indicating that it is excellent in aesthetic elements that look like printing paper.

<Ink absorbability>
Using an ink jet recording apparatus (BJ F900, manufactured by Canon Inc.), a white line (non-printing portion) lattice pattern is created in a mixed color solid pattern composed of cyan ink and magenta ink, and the ink seeps into the lattice visually. Evaluated.
A: The lattice is completely clear.
○: Ink oozing is observed on only a part of the lattice.
(Triangle | delta): A grating | lattice becomes narrow and the bleeding of an ink is seen generally.
X: Lattice is absent due to ink bleeding.

<Print density>
Using the ink jet recording apparatus, a solid pattern was printed with black ink, and the optical reflection density of the printed portion was measured with a Macbeth RD-918 model. If the print density is 1.90 or more, the ink jet recording sheet is satisfactory.

<Operability>
The cast layer was evaluated by the releasability of the coating layer from the mirror roll.
○: The coating layer is released from the mirror roll without any problem.
(Triangle | delta): The coating layer has adhered slightly to the mirror surface roll, and it is a little difficult to release.
X: The coating layer sticks to the mirror roll.

  From Table 1, the inkjet recording sheets of Examples 1 to 9 produced by the method for producing an inkjet recording sheet of the present invention have a very high print density, excellent ink absorbability, and for silver salt photography. Has the same image clarity as photographic paper.

  On the other hand, as in Comparative Examples 1 and 2, when the glossy expression layer is not provided with an aqueous liquid containing a water-soluble cationic substance between the time when the glossy expression layer is provided and when it is pressed against the mirror roll. A sufficient print density cannot be obtained. Further, as in Comparative Examples 3 and 4, when no nip water is applied and no liquid pool of nip water is formed in the press nip portion that is in pressure contact with the mirror roll, the adhesion between the gloss developing layer and the mirror roll is poor. Since a uniform glossy surface cannot be obtained, sufficient image clarity cannot be obtained. Furthermore, since the glossy surface is non-uniform, the print density is not sufficient. In addition, when an aqueous liquid containing a water-soluble cationic substance is applied after casting by the coagulation method as in Comparative Example 5, the image clarity is greatly reduced although the printing density is high. Even in the case of satisfactory quality could not be obtained.

Claims (3)

  An ink-absorbing layer consisting of at least one layer is provided on a gas-permeable support, and a gloss-expressing layer containing aluminum oxide or alumina hydrate is provided on the ink-absorbing layer. In the method of manufacturing an inkjet recording sheet, which is pressed and dried on a heated mirror roll while it is in a wet state, the glossy layer is solidified and then nip water is applied to the glossy layer. In the press nip portion that is pressed against the mirror surface roll, a nip water pool is formed, and the water-soluble cationic substance is applied on the gloss development layer after the gloss development layer is formed until it is pressed against the mirror roll. A method for producing an inkjet recording sheet, comprising applying an aqueous liquid to be contained.   2. The method for producing an ink jet recording sheet according to claim 1, wherein an aqueous liquid containing the water-soluble cationic substance is applied as a coagulating liquid at the time of coagulation treatment.   The method for producing an ink jet recording sheet according to claim 1, wherein an aqueous liquid containing the water-soluble cationic substance is applied as nip water.