JP5257294B2 - Inkjet recording sheet - Google Patents

Description

  The present invention relates to an ink jet recording sheet having a texture of coated paper for printing.

In recent years, as a means for displaying image information, etc. produced by a personal computer on a recording sheet, solution dye ink or pigment ink is ejected from the nozzle onto the recording sheet using heat or pressure as a driving source, and an image is formed with the ink. Ink jet recording methods for performing printing and electrophotographic recording methods for performing printing by forming an image by transferring toner onto a recording sheet are used.
Also, in the field of commercial printing, the inkjet recording method and electrophotographic recording method that are optimal for printing a small number of copies and variable information printing (variable printing) because digital information can be directly printed on media such as paper without making a plate. Has been introduced in the field of on-demand printing.
Recently, with the improvement in performance of recording devices such as high-speed, high-definition, and full-color printing, and the expansion of applications, it has a texture similar to that of offset prints on coated paper for printing on inkjet recording sheets. There is a growing demand to create documents.

  However, when an aqueous coating liquid containing a pigment and a binder such as an aqueous resin is applied to a paper and dried, and the manufactured general-purpose printing paper is used in an ink jet recording system, there are various problems. That is, when general-purpose printing paper is used in the inkjet recording method, the ink absorption is slow and the ink is difficult to dry. In particular, when a gloss imparting or smoothing process such as a super calender or gloss calender is performed, high transparency is achieved. Due to vaporization and pore reduction, the ink absorption is further delayed, and the problem that the ink is difficult to dry tends to occur.

Conventionally, as an ink receiving layer of an ink jet recording sheet, a pigment-based receiving layer having high ink absorbability using amorphous silica (including colloidal silica), alumina, alumina hydrate, and aluminosilicate as a main component, In addition, a resin-based receiving layer that uses a water-soluble resin such as gelatin as a main component and swells ink for recording is used. However, these ink jet recording sheets do not have a texture of coated paper for printing at all, and are expensive, so that they are not practically used in the field of on-demand printing.
A recording body (Patent Document 1) in which a cationic resin is applied to the surface of pigment coated paper, a recording body (Patent Document 2) in which a pigment coating layer is formed with a coating liquid containing a cationic resin, and the like have been proposed. However, the ink absorption speed cannot be sufficiently obtained.

  In addition, as an ink jet recording sheet for pigment ink, a recording body (Patent Documents 3 and 4) in which a colloidal silica layer is provided on an ink absorbing layer, an undercoat layer containing a pigment, and a cationic resin topcoat layer ( Patent Documents 5 and 6) are disclosed, however, the coating of colloidal silica or a cationic resin on the surface impairs ink absorbability and exhibits a unique glossy feeling similar to a silver salt photograph. The texture of the coated paper for printing cannot be obtained. Moreover, it becomes an expensive recording sheet and is not suitable for the on-demand printing field.

JP 2000-256992 A JP 2004-209965 A JP 2000-190626 A JP 2001-150800 A JP 2004-262232 A JP 2005-280035 A

  An object of the present invention is to provide an ink jet recording sheet mainly for pigment ink having the texture of a coated paper for printing.

In order to solve the above problems, the present inventors have developed an ink-receiving layer using as a main component the material used in the coated paper for printing, that is, as a pigment, amorphous silica, alumina, alumina hydrate, alumino Research was conducted to provide an ink-receiving layer having ink-jet recording suitability without containing a silicate and without using a cationic resin.
We used white pigments used in coated paper for printing as pigments and adhesives in the ink-receiving layer, and examined the use of water-soluble polyvalent metal salts to improve ink absorption. When the paint is prepared, the paint thickens excessively, so that it cannot be applied, or it must be applied at a reduced paint concentration. In this case, there is a problem that the drying load increases. I understood.
As a result of intensive studies, the present inventors have formulated a specific water-soluble polyvalent metal salt and a surfactant in a coating layer mainly composed of a white pigment and a binder in order to solve the above problem. Thus, the inventors have found that this can be achieved, and have reached the present invention.

(1) In an ink jet recording sheet having an ink receiving layer on at least one surface on a support, the ink receiving layer contains a pigment and an adhesive in a proportion of 2 to 50 parts by mass of the adhesive with respect to 100 parts by mass of the pigment, Further, it contains a surfactant and at least one water-soluble polyvalent metal salt selected from calcium nitrate, magnesium nitrate, magnesium sulfate, calcium acetate, and magnesium acetate, and the pigment is a white pigment. An ink jet recording sheet for pigment ink, wherein the receiving layer contains substantially no cationic resin.
In the present invention, the white pigment does not include amorphous silica, alumina, or aluminosilicate.
(2) The inkjet recording sheet for pigment ink according to (1), wherein the cloud point of the surfactant is 50 ° C. or higher.
(3) The inkjet recording sheet for pigment ink according to (1) or (2), wherein the white pigment is at least one selected from calcium carbonate, kaolin (including clay), and talc.
(4) The ink-jet recording sheet for pigment ink according to (3), wherein the ink receiving layer further contains a hollow plastic pigment as a pigment and is subjected to a calender treatment.
(5) The ink jet recording sheet for pigment ink according to any one of (1) to (4), wherein the adhesive contains starch or / and a styrene butadiene copolymer latex.

  ADVANTAGE OF THE INVENTION According to this invention, it can provide the inkjet recording sheet for pigment inks which has the feel of the coated paper for printing, and the ink absorptivity of pigment ink is favorable. This recording sheet is inexpensive and suitable as an ink jet recording sheet used in the on-demand printing field.

<Ink receiving layer>
The ink receiving layer in the inkjet recording sheet of the present invention contains a pigment and an adhesive in a proportion of 2 to 50 parts by mass of the adhesive with respect to 100 parts by mass of the pigment, and further includes a surfactant, calcium nitrate, magnesium nitrate, It contains at least one water-soluble polyvalent metal salt selected from magnesium sulfate, calcium acetate, and magnesium acetate, and the pigment does not include a white pigment (amorphous silica, alumina, alumina hydrate, aluminosilicate) In addition, the ink receiving layer is substantially free of a cationic resin. The fact that the ink-receiving layer substantially does not contain a cationic resin means that the cationic resin is not blended as an ink fixing agent for an ink jet recording sheet, and does not prevent addition for other purposes. For example, it is possible to use a cationic binder, a surfactant, an auxiliary agent, and the like, and they can be blended as long as the effects of the present invention are not impaired.

(Water-soluble polyvalent metal salt)
As the water-soluble polyvalent metal salt, at least one selected from calcium nitrate, magnesium nitrate, magnesium sulfate, calcium acetate, and magnesium acetate is used. In addition, the water-soluble polyvalent metal salt in the present invention includes hydrates. For example, in the case of magnesium sulfate, either magnesium sulfate anhydrous or magnesium sulfate heptahydrate or both may be used. Monovalent water-soluble metal salts such as sodium and potassium do not absorb the pigment ink quickly, and the water-soluble metal salt of aluminum has a very large viscosity increase, and the coating concentration must be lowered. This is not preferable because the drying load increases. The blending amount of these water-soluble polyvalent metal salts is not particularly limited, but it is preferably 1 to 70 parts by mass with respect to 100 parts by mass of the total pigment because the ink absorbability is excellent, and preferably 3 to 60 parts by mass. Is more preferable. Even if the blending amount is less than 1 part by mass, the ink absorptivity is better than that without blending, but the desired ink absorptivity cannot be obtained, and when it exceeds 70 parts by mass, the effect on the ink absorptivity is saturated. If the amount is more than this, the cost increases.

(Surfactant)
The surfactant is used as an essential material because it exhibits an effect of reducing excessive thickening of the paint generated when a pigment, a binder, and a water-soluble polyvalent metal salt are mixed. The surfactant is not particularly limited, and may be an ether type such as polyoxyethylene polyoxypropylene lauryl myristyl ether, polyoxyethylene alkyl ether, polyoxyalkylene tridecyl ether, polyoxyalkylene lauryl ether, polyoxyalkylene alkyl ether or the like. Examples include alkyl polyetheramine types such as oxyethylene alkyl-propylene diamine. The blending amount of the surfactant is not particularly limited, and it is preferable to appropriately determine the blending amount in consideration of the physical properties of the paint. The amount is generally 0.3 to 7 parts by mass, preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the total pigment in the ink receiving layer. If the blending amount is too small, the effect of reducing the viscosity is small and coating becomes difficult. If the blending amount is excessive, foaming of the paint is severe and coating becomes difficult.
The cloud point of the surfactant is preferably 50 ° C. or higher, and more preferably 55 ° C. or higher. When the cloud point is less than 50 ° C., when the temperature of the paint rises to 40 to 45 ° C., the effect of suppressing excessive thickening is small, which may result in poor paint circulation during operation.

(Pigment)
Examples of the pigment include known white pigments used for printing coated paper. For example, calcium carbonate, kaolin (including clay), zinc oxide, aluminum hydroxide, zeolite, synthetic zeolite, sepiolite, smectite, synthetic smectite, magnesium silicate, magnesium carbonate, magnesium oxide, diatomaceous earth, hydrotalcite, styrene, ethylene, Organic polymer fine particles of butadiene, vinyl chloride, polyurethane, acrylic, vinyl acetate, polycarbonate, nylon, and copolymers thereof, styrene plastic pigment, styrene-butadiene plastic pigment, styrene-acrylic plastic pigment, acrylic plastic Pigments, urethane plastic pigments, urea resin plastic pigments, benzoguanamine plastic pigments, etc. One or more kinds are selected and used as appropriate according to the purpose from among.
Among them, when using at least one selected from calcium carbonate (for example, light calcium carbonate, heavy calcium carbonate), kaolin (for example, engineered kaolin, deramikaolin, calcined kaolin, clay, calcined clay, etc.), talc Since the texture of the coated paper for printing becomes closer, it is preferable. In addition, when a hollow plastic pigment is blended, glossiness due to the calendar treatment is large and preferable. In the present invention, the white pigment does not include amorphous silica, alumina, or aluminosilicate, but may be added as long as the effect of the ink receiving layer is not impaired.

(binder)
A known binder used in conventional coated paper for printing can be used. Oxidized starch, enzyme-modified starch, thermochemically modified starch, esterified starch, etherified starch, cationic starch, amphoteric starch and other starch derivatives, cellulose derivatives such as carboxymethylcellulose and hydroxyethylcellulose, gelatin, casein, soy protein, natural rubber , Water-soluble polymers such as polyvinyl alcohol, polydienes such as isoprene, neoprene and polybutadiene, polyalkenes such as polybutene, polyisobutylene, polypropylene and polyethylene, vinyl halide, vinyl acetate, styrene, (meth) acrylic acid, (meth) Vinyl polymers and copolymers such as acrylic ester, (meth) acrylamide and methyl vinyl ether, synthetic rubber latexes such as styrene-butadiene and methyl methacrylate-butadiene, polyvinyl alcohol, Synthetic rubber latex having a trunnion soap as a protective colloid layer, polyurethane resins, polyester resins, polyamide resins, olefin - maleic anhydride resins, synthetic resins such as melamine resins and the like. Among these, one or more kinds are appropriately selected and used according to the purpose.
Although the compounding quantity of a binder is not specifically limited, It is preferable to set it as 2-50 mass parts with respect to 100 mass parts of all pigments, and it is more preferable to set it as 4-40 mass parts. When the blending amount is less than 2 parts by mass, the coated surface may be easily scratched. When the blending amount exceeds 50 parts by mass, when the paper is stacked in the paper discharge unit or when it is wound on a roll after printing. This is not preferable because of the effect of the ink absorption lowering and the occurrence of set-off, and guide roll stains and paper feed roll stains in the printing process.

(Other ingredients)
Furthermore, various auxiliary agents as necessary, for example, pH adjusting agents, viscosity adjusting agents, softening agents, gloss imparting agents, waxes, dispersants, flow modifiers, stabilizers, antistatic agents, cross-linking agents, sizing agents, fluorescence Brighteners, colorants, ultraviolet absorbers, antifoaming agents, water resistance agents, plasticizers, lubricants, preservatives, fragrances and the like are appropriately blended as necessary.

<Support>
The support according to the present invention is not particularly limited, and examples thereof include a paper substrate, a film, and a bonded product of a film and a paper substrate. Among these, it is preferable to use a paper substrate from the surface. As the support, a sheet having water absorption is preferable, and in particular, according to JIS P8140, the Cobb method water absorption with a contact time with water of 20 seconds is 0.12 to 1.3 g / m ² per 1 g / m ^{2 of the} support. m ² is preferable. When it is less than 0.12 g / m ² , the ink absorbability decreases in ink jet recording suitability, and when it exceeds 1.3 g / m ² , the absorption of the coating liquid to the support increases, and wrinkles and the like occur during coating. This is likely to cause manufacturing problems. In the case of a bonded product of a film and a paper substrate, the water absorption is the Cobb method water absorption per 1 g / m ² of the sheet before joining on the ink receiving layer side.

  There are no particular limitations on the method and type of pulp constituting the paper substrate, for example, chemical pulp such as KP, mechanical pulp such as SGP, RGP, BCTMP, and CTMP, waste paper pulp such as deinked pulp, kenaf, bamboo, Non-wood pulp such as straw and hemp is used. In addition, organic synthetic fibers such as polyamide fibers and polyester fibers, recycled fibers such as polynosic fibers, and inorganic fibers such as glass fibers, ceramic fibers, and carbon fibers can be mixed. Among these, use of chlorine-free pulp such as ECF pulp and TCF pulp is preferable.

  Further, a filler may be blended in the paper substrate as necessary. As the filler, various pigments generally used for fine paper can be used, such as kaolin, calcined kaolin, calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide, talc, zinc oxide, alumina, magnesium carbonate, magnesium oxide, Mineral pigments such as aluminosilicate, silica, white carbon, bentonite, zeolite, sericite and smectite, and micro hollow particles of polystyrene resin, urea resin, melamine resin, acrylic resin and vinylidene chloride resin, dense Organic pigments such as mold particles and through-hole particles.

  In addition, when making a paper substrate, in addition to pulp fibers and fillers, various anionic, nonionic, and cationic properties that have been used in the past are included in the stock, as long as the desired effects of the present invention are not impaired. Alternatively, various internal additives for papermaking such as amphoteric retention improver, freeness improver, starch, paper strength enhancer and internal additive sizing agent can be appropriately selected and used as necessary. Furthermore, internal additives for papermaking such as dyes, fluorescent brighteners, pH adjusters, antifoaming agents, pitch control agents, slime control agents and the like can be added as necessary.

  There are no particular limitations on the paper making method of the paper substrate. For example, an acid paper making method in which the paper making pH is around 4.5, a weakly acidic paper making pH of about 6 containing an alkaline filler such as calcium carbonate as a main component, and a paper making pH of about 9 All papermaking methods such as neutral papermaking, which is carried out with weak alkalinity, can be applied, and the paper machine should also be a long net paper machine, twin wire paper machine, circular net paper machine, Yankee paper machine as appropriate Can do.

On one or both sides of the paper substrate obtained by the above method, a pigment, a binder, a surface sizing agent, a cationic resin, an anionic resin, a nonionic resin, a surfactant, a pH adjusting agent, a viscosity adjusting agent, a softening agent, Gloss imparting agents, waxes, dispersants, flow modifiers, stabilizers, antistatic agents, cross-linking agents, sizing agents, fluorescent whitening agents, colorants, UV absorbers, antifoaming agents, water-resistant agents, water-soluble Appropriately adjusting one or two or more kinds of auxiliary agents such as metal salts, plasticizers, lubricants, preservatives, and fragrances, and applying the under layer, this under layer was applied. The later paper substrate can be used as a support.
The basis weight of the paper substrate used in the present invention is not particularly limited, but those having a range of 30 g to 300 g / m ² are usually used.

  Examples of the film that is a support used in the present invention include acetate film, cellulose triacetate film, nylon film, polyester film, polycarbonate film, polystyrene film, polyphenylene sulfide film, polypropylene film, polyimide film, cellophane and the like. I can do it. A film containing additives such as an inorganic pigment, an organic pigment, an ultraviolet absorber, a light stabilizer, an antioxidant, a fluorescent dye, a crosslinking agent, a lubricant, and a release agent is used as necessary. The method for producing the film is not particularly limited, and a known method can be used. The film used as the support according to the present invention includes what is generally called synthetic paper. Although the thickness of this film is not specifically limited, Usually, the thing of the range of 40 micrometers-300 micrometers is used.

  A bonded product of a film and a paper substrate can be obtained by a known method. The thickness of the laminate of the film and paper substrate used as the support is not particularly limited, but is usually in the range of 40 μm to 300 μm.

  When the paint is provided on one side, various known coating layers can be provided on the back side for antistatic, curl prevention, adhesion improvement, printing suitability, improvement in feeding / discharging suitability with a printer, etc. . It is of course possible to add application suitability to the back surface by applying various processes such as adhesion, magnetism, flame resistance, heat resistance, water resistance, oil resistance, and slip resistance.

<Coating device>
The method for forming the coating layer is not particularly limited, and a commonly used coating apparatus is used.
For example, blade coater, air knife coater, spray coater, rod blade coater, roll coater, reverse roll coater, bar coater, curtain coater, die slot coater, gravure coater, champlex coater, brush coater and two-roll coater, and metering blade Various known coating apparatuses such as a size press coater, a bill blade coater, a short dwell coater, a lip coater, and a gate roll coater can be used. The coating surface may be single-sided or double-sided, and the coating amount is preferably in the range of 1 to 15 g / m ² , more preferably in the range of ^{2 to} 13 g / m ² . If the coating amount is less than 1 g / m ² , the covering property of the base paper becomes insufficient and it becomes difficult to obtain the texture of the printing paper, and if it is 15 g / m ² or more, the cost is high and the drying load increases, which is not preferable.

(Glossing and smoothing treatment)
After the coating layer is formed on the support, gloss may be imparted and smoothed by a calender or the like. Examples of the smoothing device include a normal super calender, gloss calender, soft calender, and shoe nip calender. Used. Processing is performed by appropriately adjusting the processing conditions such as the configuration of the pressure device, the number of pressure nips, and heating.

  The present invention will be specifically described by the following examples, but of course, they are not intended to limit the scope of the present invention. In the examples, “parts” and “%” represent “parts by mass (solid component)” and “mass%” unless otherwise specified.

Example 1
(Production of support)
100 parts hardwood bleached kraft pulp, 10 parts light calcium carbonate, 0.3 parts cationic starch (trade name: Kate F, manufactured by Oji National), paper strength enhancer (trade name: Polymaron 619, manufactured by Arakawa Chemical Industries) 0 .1 part, alkyl ketene dimer (trade name: SPK-910, manufactured by Arakawa Chemical Industries, Ltd.) 0.02 part, add water and mix well to prepare a stock with a slurry concentration of 0.05%. Using a long mesh multi-cylinder paper machine, using a two-roll size press machine, 2% solids starch (trade name: Ace B, manufactured by Oji Cornstarch Co., Ltd.) per side of the base paper Cobb water absorption of 75 g / m ² (cobb water absorption per 1 g / m ^{2 of} support) with a solid content of 0.5 g / m ^{2 applied} , dried, and a contact time with water specified in JIS P8140 of 20 seconds. 0.75 g / m ² ), basis weight Produced a support of 100 g / m ² .

[Preparation of paint A]
Cores disperser by adding 0.1 parts of dispersant (trade name: Aron T-50, manufactured by Toagosei Co., Ltd.) to 35 parts of kaolin (trade name: Astra Plus, manufactured by Imeris Minerals Japan), adding water. Then, 65 parts of light calcium carbonate (trade name: TP-123CS, manufactured by Okutama Kogyo Co., Ltd.) was added to prepare a pigment slurry. To 100.1 parts of this pigment slurry, 4 parts of starch (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.), 15 parts of latex (trade name: T-2540A, manufactured by JSR Corporation), surfactant (trade name) : Leox 2160C, chemical name: polyoxyethylene polyoxypropylene lauryl myristyl ether, cloud point 60 ° C, manufactured by Lion Corporation) 3 parts, water-soluble metal salt (chemical name: calcium nitrate tetrahydrate) 15 parts, antifoaming agent (Product name: SN777, manufactured by San Nopco) 0.2 parts, fluorescent whitening agent (trade name: Kaya Hall BPS Liquid Conk, manufactured by Nippon Kayaku Co., Ltd.) 0.5 parts, water was added and the solid content concentration was 34%. Paint A was prepared.

[Preparation of recording sheet]
The coating A was applied to both sides of the 100 g / m ² support obtained above using a blade coater and dried so that the dry coating mass per side was 7.0 g / m ^2. A recording sheet having an amount of 114 g / m ² was produced.

Example 2
(Production of support)
It was produced in the same manner as in Example 1.
[Preparation of paint B]
Cores disperser by adding 0.1 parts of dispersant (trade name: Aron T-50, manufactured by Toagosei Co., Ltd.) to 25 parts of kaolin (trade name: Astra Plus, manufactured by Imeris Minerals Japan), adding water. Then, 50 parts of light calcium carbonate (trade name: TP-123CS, manufactured by Okutama Kogyo Co., Ltd.) and 25 parts of hollow plastic pigment (AE-852, manufactured by JSR Corporation) are added, and the pigment slurry is added. Created. To 100.1 parts of this pigment slurry, 4 parts of starch (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.), 15 parts of latex (trade name: T-2540A, manufactured by JSR Corporation), surfactant (trade name) : Leox 2160C, chemical name: polyoxyethylene polyoxypropylene lauryl myristyl ether, manufactured by Lion Corporation 3 parts, water-soluble metal salt (chemical name: calcium nitrate tetrahydrate) 15 parts, antifoaming agent (trade name: SN777) , Sannopco Co., Ltd.) 0.2 parts, optical brightener (trade name: Kaya Hall BPS Liquid Conk, Nippon Kayaku Co., Ltd.) 0.5 parts, and water is added to prepare paint B with a solid content concentration of 34%. did.

[Preparation of recording sheet]
The coating B was coated on both sides of the 100 g / m ² support obtained above using a blade coater, dried so that the dry coating mass per side was 7.0 g / m ² , Supercalendering was performed at a nip pressure of 30 kg / cm to produce a recording sheet having a basis weight of 114 g / m ² .

Example 3
A recording sheet was prepared in the same manner as in Example 2, except that 15 parts of magnesium nitrate hexahydrate was used instead of 15 parts of calcium nitrate tetrahydrate in the preparation of the coating material B of Example 2.

Example 4
A recording sheet was prepared in the same manner as in Example 2 except that 15 parts of magnesium sulfate heptahydrate was used instead of 15 parts of calcium nitrate tetrahydrate in the preparation of the coating material B of Example 2.

Example 5
A recording sheet was prepared in the same manner as in Example 2 except that 15 parts of calcium acetate monohydrate was used instead of 15 parts of calcium nitrate tetrahydrate in the preparation of the coating material B of Example 2.

Example 6
A recording sheet was prepared in the same manner as in Example 2, except that 15 parts of magnesium acetate tetrahydrate was used instead of 15 parts of calcium nitrate tetrahydrate in the preparation of the coating material B of Example 2.

Example 7
In the preparation of the coating material B of Example 2, the same procedure as in Example 2 was conducted except that 3 parts of Nimine DT-208 (polyoxyethylene alkylpropylenediamine, manufactured by NOF Corporation) was used instead of Leox 2160C as the surfactant. Thus, a recording sheet was produced.

Example 8
In preparation of the coating material A of Example 1, instead of 35 parts of kaolin (trade name: Astraplus, manufactured by Imeris Minerals Japan) and 65 parts of light calcium carbonate (trade name: TP-123CS, manufactured by Okutama Kogyo Co., Ltd.) A recording sheet was prepared in the same manner as in Example 1 except that 100 parts of kaolin (trade name: Astra Plus, manufactured by Imeris Minerals Japan) was used.

Example 9
In preparation of the coating material A of Example 1, instead of 35 parts of kaolin (trade name: Astraplus, manufactured by Imeris Minerals Japan) and 65 parts of light calcium carbonate (trade name: TP-123CS, manufactured by Okutama Kogyo Co., Ltd.) A recording sheet was prepared in the same manner as in Example 1 except that 100 parts of light calcium carbonate (trade name: TP-123CS, manufactured by Okutama Kogyo Co., Ltd.) was used.

Example 10
In preparation of the coating material A of Example 1, instead of 35 parts of kaolin (trade name: Astraplus, manufactured by Imeris Minerals Japan) and 65 parts of light calcium carbonate (trade name: TP-123CS, manufactured by Okutama Kogyo Co., Ltd.) A recording sheet was prepared in the same manner as in Example 1 except that 100 parts of calcined kaolin (trade name: Ansilex 93, manufactured by BASF) was used.

Example 11
In preparation of the coating material A of Example 1, instead of 35 parts of kaolin (trade name: Astraplus, manufactured by Imeris Minerals Japan) and 65 parts of light calcium carbonate (trade name: TP-123CS, manufactured by Okutama Kogyo Co., Ltd.) A recording sheet was prepared in the same manner as in Example 1 except that 100 parts of talc (trade name: NTP-2, manufactured by Nippon Talc Co., Ltd.) was used.

Comparative Example 1
A recording sheet was prepared in the same manner as in Example 1 except that 15 parts of the water-soluble metal salt (chemical name: calcium nitrate tetrahydrate) was removed.

Comparative Example 2
A recording sheet was prepared in the same manner as in Example 1 except that 15 parts of the water-soluble metal salt (chemical name: calcium nitrate tetrahydrate) was changed to 15 parts of lithium acetate dihydrate.

Comparative Example 3
A recording sheet was prepared in the same manner as in Example 1 except that 15 parts of water-soluble metal salt (chemical name: calcium nitrate tetrahydrate) was changed to 15 parts of potassium iodide.
Comparative Example 4
A paint was prepared in the same manner as in Example 1 except that 15 parts of the water-soluble metal salt (chemical name: calcium nitrate tetrahydrate) was changed to 15 parts of aluminum sulfate 14-18 hydrate. Because the paint was thickened, it could not be applied and a recording sheet could not be created.

Comparative Example 5
In Example 1, a coating material was prepared in the same manner as in Example 1 except that 3 parts of the surfactant (trade name: Leox 2160C, chemical name: polyoxyethylene polyoxypropylene lauryl myristyl ether, manufactured by Lion Corporation) were excluded. However, since the paint was thickened, it could not be applied and a recording sheet could not be prepared.

Comparative Example 6
[Production of support]
It was produced in the same manner as in Example 1.
[Preparation of paint C]
Water is added to 100 parts of silica (trade name: Nipgel AY-601, manufactured by Tosoh Silica Co., Ltd.) and dispersed in water using a Coreless disperser, and then a cationic resin (trade name: Unisense CP-101, manufactured by Senka Co., Ltd.). ) 8 parts was added and stirred and mixed, 5 parts of polyvinyl alcohol (trade name: PVA117, manufactured by Kuraray Co., Ltd.) and 20 parts of cationic urethane resin (trade name: Pascoal JK-870, manufactured by Meisei Chemical Industry Co., Ltd.) were added. A paint C having a solid content of 12% was prepared.
[Preparation of recording sheet]
On both surfaces of the 100 g / m ² support obtained above, paint C was applied and dried using a die coater so that the dry coating amount per side was 7.0 g / m ^2. A recording sheet having an amount of 114 g / m ² was produced.

Comparative Example 7
In the preparation of the coating material C of Comparative Example 6, the coating material was prepared using 100 parts of silica (trade name: Aerosil A200, manufactured by Degussa) instead of 100 parts of silica (trade name: Nipgel AY-601, manufactured by Tosoh Silica Co., Ltd.). Then, using a die coater, the prepared paint is coated and dried so that the dry coating amount per side is 7.0 g / m ² , and is subjected to supercalender treatment with a nip pressure of a linear pressure of 30 kg / cm 2. A recording sheet having a basis weight of 114 g / m ² was produced.

Example 12
A recording sheet was produced in the same manner as in Example 1 except that the coating material A in Example 1 was changed to the coating material D.
[Preparation of paint D]
To 75 parts of calcined kaolin (trade name: Ansilex, manufactured by BASF), 0.4 parts of dispersant (trade name: Aron T-50, manufactured by Toagosei Co., Ltd.) is added, water is added, and a coreless disperser is used. Then, 25 parts of hollow plastic pigment (AE-852, manufactured by JSR Corporation) was added to prepare a pigment slurry. To 100.4 parts of this pigment slurry, 6 parts of starch (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.), 16 parts of latex (trade name: T-2540A, manufactured by JSR Corporation), and a surfactant (trade name) : Neugen TDX-120D, chemical name: polyoxyalkylene tridecyl ether, cloud point 79.4 ° C, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 3 parts, water-soluble metal salt (chemical name: magnesium nitrate anhydride) 20 parts, Add 1.5 parts of foaming agent (trade name: SN777, manufactured by San Nopco), 0.5 part of fluorescent whitening agent (trade name: Kaya Hall BPS Liquid Conk, manufactured by Nippon Kayaku Co., Ltd.), add water to add solid content 32% paint D was prepared.

Example 13
In the preparation of the paint D of Example 12, the surfactant was changed to Neugen TDX-120D, and Neugen TDX-50 (chemical name: polyoxyalkylene tridecyl ether, cloud point 36.4 ° C., Daiichi Kogyo Seiyaku Co., Ltd.) (Manufactured) A recording sheet was prepared in the same manner as in Example 12 except that the amount was 3 parts.

Example 14
In the preparation of the paint D of Example 12, the surfactant was changed to Neugen TDX-120D, and Neugen LF-80X (chemical name: polyoxyalkylene alkyl ether, cloud point 56 ° C., manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 3 A recording sheet was produced in the same manner as in Example 12 except that the parts were used.

The obtained inkjet recording sheet was evaluated by the following method. The obtained results are shown in Table 1.
(Evaluation)
[Inkjet recording suitability]
Ink absorbability evaluation Solid printing was performed with an inkjet printer (trade name: GP-700, manufactured by Epson Corporation), and the time until ink droplet erasing immediately after printing was measured. If it is 15 seconds or more, it causes problems such as set-off, which is not preferable.

[Blank gloss]
In accordance with JISP8142, measurements were made using a 75 degree gloss meter.
[Texture evaluation of printing paper]
The commercially available coated paper for printing (OK Topcoat (registered trademark) +, manufactured by Oji Paper Co., Ltd.) and the surface feeling (feel of the coated layer surface) were visually compared and evaluated.
○: A substantially homogeneous feel.
Δ: Slightly difficult to feel the coated paper for printing.
Δ ×: A surface feeling between Δ and ×: Different from the surface feeling of the coated paper for printing.

In addition, for Example 1, Example 2, and Examples 12 to 14, in order to determine the operability during production, the circulation state at a coating temperature of 45 ° C. was evaluated, and the results are shown in Table 2.
(Evaluation)
[Circulating condition when the paint temperature is 45 ℃]
Coating was performed using a blade coater with the coating material adjusted to about 45 ° C., and it was observed whether the state of the coating liquid after 30 minutes was suitable for operation.
A: Circulated quickly and there is no problem in operation.
A to B: Slightly inferior to ◎ but better than ○.
○: Slightly thickened, but no problem in operation.
×: Circulation is poor and operation is not possible.

表１から明らかなように、本発明の記録シートは、塗料の過度な増粘を抑制し、インクジェット記録方式での顔料インクの吸収性が良好である。また、表２から明らかなように、界面活性剤の曇点が５０℃以上であると、塗料の温度が上昇しても、安定して操業することができる。

As is clear from Table 1, the recording sheet of the present invention suppresses excessive thickening of the paint and has good absorbability of the pigment ink in the ink jet recording system. Further, as is apparent from Table 2, when the cloud point of the surfactant is 50 ° C. or higher, even if the temperature of the coating material is increased, it can be stably operated.

  The present invention is an ink jet recording sheet having good absorbability of pigment ink, and is very useful as an ink jet recording sheet in the on-demand printing field because it is close to the texture of a coated paper for printing. For example, application to a line head ink jet printer having a high recording speed is also possible.

Claims (5)

In an ink jet recording sheet having an ink receiving layer on at least one surface on a support, the ink receiving layer contains a pigment and an adhesive in a ratio of 2 to 50 parts by mass of the adhesive with respect to 100 parts by mass of the pigment, and further the interface An activator and at least one water-soluble polyvalent metal salt selected from calcium nitrate, magnesium nitrate, magnesium sulfate, calcium acetate, and magnesium acetate; and the pigment is a white pigment, and the ink receiving layer comprises An ink jet recording sheet for pigment ink, which is substantially free of a cationic resin. 2. The inkjet recording sheet for pigment ink according to claim 1, wherein the cloud point of the surfactant is 50 ° C. or higher. The inkjet recording sheet for pigment ink according to claim 1 or 2, wherein the white pigment is at least one selected from calcium carbonate, kaolin, and talc. The inkjet recording sheet for pigment ink according to claim 3, wherein the ink receiving layer further contains a hollow plastic pigment as a pigment and is subjected to a calendering treatment. The inkjet recording sheet for pigment ink according to any one of claims 1 to 4, wherein the adhesive contains starch or / and a styrene-butadiene copolymer latex.