JP2008143134A - Manufacturing method of ink-jet recording sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the manufacturing method of an ink-jet recording sheet, which is excellent in ink absorbency, provides high printing density, and, in addition, has fairly surface smoothness and moderate gloss though less than those of glossy paper in photographic tone even not glossy-treated by a cast-coating method. <P>SOLUTION: In the manufacturing method of the ink-jet recording sheet, which has at least one ink accepting layer including fine particles having an average particle diameter of ≥5 nm and ≤700 nm on a water-absorbent support, a pre-treating liquid, which includes material having an action for gelating or thickening an ink accepting layer forming coating liquid by contacting therewith and has a viscosity of 2-20 mPa s, coats the support prior to the coating with the ink accepting layer forming coating liquid on the support. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a recording sheet applied to an ink jet recording system.

The ink jet recording method in which water-based ink is ejected from a fine nozzle toward a recording sheet and an image is formed on the recording surface of the sheet is low in noise during recording, easy to form a full-color image, high speed It is widely used in terminal printers, facsimiles, plotters, form printing, and the like due to the fact that recording is possible and the recording cost is lower than other printing apparatuses.
On the other hand, due to the rapid spread of printers, high definition and high speed, and the advent of digital cameras, the characteristics of ink jet recording sheets are also required to be enhanced. That is, there is a strong demand for an ink jet recording sheet that has excellent ink absorption, recording density, water resistance, and light resistance, and has image quality, gloss, and storability comparable to silver salt photography. Furthermore, it is also required to prevent cracking and cracking of the ink receiving layer in the ink jet recording sheet.
Furthermore, with the widespread use of inkjet recording systems, there is an increasing demand for inkjet recording sheets having a moderate glossiness and a relatively low cost, that is, inkjet recording sheets with excellent cost performance.

The ink jet recording sheet in which the ink receiving layer containing fine particles is coated on the support has good ink absorbability, and the ink receiving layer made of fine particles has high transparency, so the color of the ink is clear. High print density can be obtained. Further, the ink receiving layer made of fine particles has excellent surface smoothness and appropriate gloss even without gloss treatment by the casting method, and meets the above market demand.
However, simply applying an ink-receiving layer containing fine particles on the support causes the coating layer to shrink and crack easily when drying in the coating drying process, resulting in poor smoothness. As a result, there is a problem that glossiness is lowered, blurring is generated along the cracks during printing, or uniformity of printing is lowered. In order to prevent cracking, the amount of the binder component of the ink receiving layer can be increased. However, this method also decreases the ink absorption speed of the ink receiving layer, so that the ink ejected by the printer cannot be immediately absorbed. In addition, there is a problem in that printing blur occurs and print quality is deteriorated.
In addition, when the coating amount of the ink receiving layer is increased, there is a disadvantage that the completed ink jet recording sheet becomes thick or becomes rigid and easily broken.

  For this reason, after coating a treatment liquid containing a material having a function of gelling or thickening in contact with a coating liquid for forming an ink receiving layer on a support in advance, an ink receiving layer is provided, whereby an ink receiving layer is provided. A method for preventing generation of cracks in the layer has already been proposed.

In Cited Document 1, an ink receiving material comprising a pigment mainly composed of synthetic silica and a binder mainly composed of polyvinyl alcohol on a base paper obtained by coating borax or boric acid at least 0.1 g / m ² per side. An ink jet recording paper coated with a layer is disclosed. However, the combination of a pigment mainly composed of synthetic silica and polyvinyl alcohol makes the pigment particles large and irregular, making it difficult to obtain gloss and lowering of print quality uniformity due to uneven penetration of borax or boric acid. Then there was a problem.

Cited Document 2 discloses a porous material containing boehmite and polyvinyl alcohol on the treated surface of a substrate surface-treated with one or more selected from the group consisting of boric acid and borate and a paper surface treating agent. A recording sheet having an ink absorbing layer is disclosed.
In Cited Document 3, in an ink jet recording sheet having a color material receiving layer on a support, boric acid or a boron compound is formed on one of the supports on the support between the support and the color material receiving layer. An ink jet recording sheet is disclosed in which 0.1 g / m ² or more is applied per surface, and the colorant receiving layer includes inorganic pigment fine particles having an average primary particle diameter of 20 nm or less and a water-soluble resin. .
In reference 4, a) an undercoat layer comprising a polymer binder and a borate or borate derivative, wherein the borate or borate derivative is present in an amount of ³ to 50 g / m ² , and the polymer An undercoat layer having a mass ratio of binder to the borate or borate derivative of 0.2: 1 to 2: 1; and b) an image-receiving layer comprising a crosslinkable polymer and particles containing hydroxyl groups. The crosslinkable polymer is present in an amount of ²⁰ to 150 g / m ² and carries an image-receiving layer having a mass ratio of the crosslinkable polymer to the particles of 10:90 to 30:70. An ink jet recording element comprising a substrate is disclosed.
Patent Document 5 discloses an ink receiving layer and a cast layer in which a crosslinking agent is applied to a support or an undercoat layer formed on the support, and a pigment and a binder that crosslinks the crosslinking agent are applied. An inkjet recording body to be formed is disclosed.

However, in these methods, a treatment liquid containing a material having an action of gelling or thickening in contact with a coating liquid for forming an ink-receiving layer coated on a water-absorbing support penetrates the support. Therefore, there is a problem if the necessary gelling or thickening action is not exhibited. Alternatively, when the support is a paper support, unevenness in the size of the paper can cause unevenness in the state of penetration of the treatment liquid, resulting in uneven ink absorbability and print quality of the ink receiving layer ( For example, when printing on the entire surface of an inkjet recording sheet, there is a problem that uniformity of print density cannot be obtained.
Japanese Patent Publication No. 7-37175 JP 11-291621 A JP 2001-246832 A JP 2003-205679 A JP 2006-142748 A

  An object of the present invention is to provide an ink-jet recording sheet in which an ink-receiving layer containing fine particles is coated on a water-absorbing support, providing excellent ink absorption, high print density, and gloss treatment by a cast method. However, the present invention is intended to provide a method for producing an inkjet recording sheet having a smooth surface and an appropriate gloss, although it does not reach photographic glossy paper. Furthermore, an object of the present invention is to provide a method for producing an ink jet recording sheet having uniform printing quality.

  In order to solve the above problems, as a result of intensive studies by the present inventors, prior to coating and providing the ink receiving layer, the ink receiving layer is brought into contact with the coating liquid for forming the gel or thickened. The present invention has found that the above-mentioned problems can be solved by applying a pretreatment liquid containing a material having an action on a support, and adjusting the viscosity of the pretreatment liquid to 2 mPas to 20 mPas (B type viscometer). Has been completed.

That is, (1) In the method for producing an ink jet recording sheet having an ink receiving layer containing at least one fine particle having an average particle diameter of 5 nm or more and 700 nm or less on a water-absorbing support, the ink receiving layer is formed on the support. Prior to application of the forming coating solution, the ink receiving layer forming coating solution contains a material that has a function of gelling or thickening when in contact with the ink receiving layer forming coating solution, and the viscosity is A method for producing an ink jet recording sheet, comprising applying a pretreatment liquid of 2 mPas to 20 mPas (B-type viscometer) on the support.
(2) Boric acid and / or borax is a material having an action of gelling or thickening upon contact with the ink receiving layer forming coating solution, and the ink receiving layer forming coating solution contains polyvinyl alcohol (1) The method for producing an ink jet recording sheet according to (1).
(3) The pretreatment liquid contains one or more selected from the group consisting of cationized cellulose, carboxymethylcellulose, hydroxyethylcellulose and hydroxypropylmethylcellulose as a viscosity modifier (1) or (2) The method for producing an inkjet recording sheet described in 1.

Furthermore, as a result of extensive studies by the present inventors, prior to coating and providing the ink receiving layer, the material is identified as a material that has the effect of gelling or thickening in contact with the ink receiving layer forming coating solution. The present inventors have found that the above-mentioned problems can be solved by applying a pretreatment liquid containing the above viscosity modifier to the support, and have completed the present invention.
(4) In a method for producing an ink jet recording sheet having an ink receiving layer containing fine particles having an average particle diameter of 5 nm or more and 700 nm or less on at least one layer on a water-absorbing support, the ink receiving layer is formed on the support. Prior to coating the coating liquid, the ink receiving layer forming coating liquid contains a material having an action of gelling or thickening when in contact with the ink receiving layer forming coating liquid. In a method for producing an ink jet recording sheet, a pretreatment liquid containing at least one selected from the group consisting of cationized cellulose, carboxymethylcellulose, hydroxyethylcellulose and hydroxypropylmethylcellulose is coated on the support. is there.

  Prior to coating and providing an ink-receiving layer on a water-absorbing support, a pretreatment liquid containing a material (gelling agent) that has an action of gelling or thickening in contact with a coating liquid for forming an ink-receiving layer When the ink-receiving layer is subsequently applied to the support, the water-soluble binder in the coating layer and the gelling agent react to form an ink-receiving layer coating solution on the support. The viscosity of the resin is increased, or gelled and crosslinked. When the ink receiving layer shrinks in the drying process of the ink receiving layer, the coating layer is cracked or generated. In the present invention, the viscosity of the ink receiving layer coating liquid on the support is increased, or gelation or crosslinking is performed. This makes it difficult to crack and has an effect. Accordingly, an inkjet recording sheet having a high glossiness can be obtained. Furthermore, according to the present invention, it is not necessary to suppress the cracking by excessively increasing the binder, so that the ink absorption speed and the ink absorption capacity of the ink receiving layer are not lowered, and the printing quality is good.

"About support"
A water-absorbing support is a base material that allows a solvent such as water to penetrate into the support when a coating solution is applied onto the support, such as paper, paperboard, cardboard, non-woven fabric, and woven fabric. It can be illustrated. Among them, the paper base is preferably used as a recording sheet, and will be described as a representative example, but is not limited to the paper base.

There are no particular restrictions on the production method or type of pulp constituting the paper substrate. Hardwood pulp, softwood pulp, chemical pulp such as KP, SP, mechanical pulp such as GP, SGP, RGP, TMP, BCTMP, CTMP, waste paper pulp such as deinked pulp, or kefna, bamboo, straw, hemp Such non-wood pulp, polyamide fibers, polyester fibers, polynosic fibers, and other organic synthetic fibers, and glass fibers, ceramic fibers, carbon fibers, and other inorganic fibers can also be used.
Moreover, a filler can be mix | blended in a paper base material as needed. The filler is not particularly limited, but various pigments generally used for fine paper, such as kaolin, calcined kaolin, calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide, talc, zinc oxide, alumina, magnesium carbonate, oxidation Mineral pigments such as magnesium, silica, white carbon, bentonite, zeolite, sericite, smectite, polystyrene resins, urea resins, melamine resins, acrylic resins, vinylidene chloride resins and their hollow micro particles Organic pigments are listed, and one or more of them can be selected and blended.
The blending amount of the filler is not particularly limited, but is usually in the range of 5 to 30% by weight. When the content is less than 5% by weight, the opacity of the paper base material is low, and the opacity of the completed inkjet recording sheet may be low. On the other hand, if it exceeds 30% by weight, the paper substrate may be less rigid or the paper's internal bond strength may be excessively reduced.
Furthermore, in addition to pulp and filler, the paper base material has various anionic, nonionic, cationic or amphoteric yield improvers, and improved drainage, as long as the effects of the present invention are not impaired. Various paper making aids such as an agent, a paper strength enhancer, and an internal 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 may be appropriately added depending on the application.
The papermaking method is not particularly limited. For example, it is applicable to all papermaking methods such as acidic papermaking with a papermaking pH of around 4.5 and weakly acidic neutral papermaking with a papermaking pH of about 9 including weakly acidic papermaking pH of about 9 including alkaline fillers such as calcium carbonate. can do. Further, as the paper machine, a long paper machine, a twin wire paper machine, a round paper machine, and a Yankee paper machine can be used as appropriate.
The paper base is a paper machine size press process, starch, polyvinyl alcohol, polyacrylamide, polyethylene glycol, sulfonated styrene resin, quaternary ammonium chloride, calcium oxide, sodium chloride, sodium nitrate, calcium chloride, various surface sizing agents A size press solution containing the above is applied to a paper substrate by a known method.

The paper substrate preferably has Oken smoothness of 50 to 500 seconds and Oken air permeability of 50 to 2000 seconds. When the Beck smoothness exceeds 500 seconds, the operability may be deteriorated, for example, streak may occur when the ink-receiving layer coating liquid is applied, or the adhesion of the paint may be deteriorated. The whiteness is preferably 85% or more from the clearness of color development in ink jet recording and the variation of white paper. The opacity is preferably 85% or more in order to prevent through printing of ink jet recording (a phenomenon in which the printing of the lower sheet can be seen through when two or more printed recording sheets are stacked). The hue is generally white from the viewpoint of color development of printing.
The size is important for uniformly applying the pretreatment liquid. The value is preferably 5 to 500 seconds in terms of Steecht sizing. When the time is less than 5 seconds, the pretreatment liquid is rapidly absorbed by the support, and the coating amount becomes excessive, and the ink absorptivity is lowered to cause printing bleed. On the other hand, when the time exceeds 500 seconds, the pretreatment liquid does not readily penetrate and drying is slowed down, and thus there is a problem that productivity of the coating machine is lowered. There is also a problem that the ink absorbability of the completed inkjet recording sheet is lowered. The Kobusaizu degree, it preferably 20ml / m ² ~500ml / m ² for the same reason.

[Pretreatment liquid]
In the first invention, the pretreatment liquid contains one or more materials having the ability to crosslink with the composition component of the ink receiving layer and capable of gelling or thickening the ink receiving layer coating liquid. The viscosity of the treatment liquid must be in a specific range.
In the second invention, the pretreatment liquid contains one or more materials having the ability to crosslink with the composition component of the ink receiving layer and can gel or thicken the ink receiving layer coating liquid, and has a viscosity. Certain materials need to be included as modifiers.
The form that satisfies both the first invention and the second invention is most preferable.

<Viscosity of pretreatment liquid>
The viscosity of the pretreatment liquid in the present invention is 2 mPas to 20 mPas. Further, it is preferably 5 mPas to 10 mPas. This viscosity is a value obtained by measurement using a “B-type viscometer BL type” manufactured by Toki Sangyo Co., Ltd. under conditions of a liquid temperature of 23 ° C. and 60 rpm. When the viscosity of the pretreatment liquid is less than 2 mPas, it is difficult to uniformly apply the pretreatment liquid to the support, and the infiltration to the support tends to be uneven, resulting in inconvenient coating unevenness. . On the other hand, when it exceeds 20 mPas, the treatment liquid hardly penetrates into the inside of the support and the surface remains wet. Therefore, when the ink receiving layer is applied continuously, there is a waiting time until the application. Therefore, it is necessary to reduce the production speed or lengthen the coating apparatus line. Alternatively, even when the ink-receiving layer is applied after winding up and storing the support, it has been found that drying takes a long time and productivity is lowered.

<Material with gelling or thickening action>
Examples of the material having an action of gelling or thickening upon contact with the ink-receiving layer-forming coating liquid in the present invention (hereinafter also referred to as a gelling agent) include, for example, boron compounds, epoxy compounds, glycidyl compounds, A zirconium compound, an aluminum compound, a chromium compound, etc. are mentioned. Among these, when combined with polyvinyl alcohol contained in the ink receiving layer described later, a boron compound is preferable and boric acid and / or borax are more preferable because of rapid progress of gelation or thickening.

Examples of boric acid include orthoboric acid, metaboric acid, hypoboric acid, tetraboric acid, and pentaboric acid. Moreover, these sodium salt, potassium salt, and ammonium salt may be sufficient. Among these, orthoboric acid and disodium tetraborate are preferable.
Borax is a hydrous borate mineral of sodium, and its composition is Na ₂ B ₄ O ₇ · 10H ₂ O. Essentially Na ₂ B ₄ O ₇ (disodium tetraborate) is the crosslinker component.

  The concentration of the gelling agent cannot be generally specified depending on the material used, but is preferably about 0.001 to 20% by mass. When the gelling agent is 0.001% by mass or more, the water-soluble resin used in the ink receiving layer described later can be sufficiently gelled or thickened by the material. On the other hand, if it is 20 mass% or less, excessive gelation or thickening can be prevented.

<Viscosity modifier>
The viscosity modifier is not particularly limited as long as the viscosity of the pretreatment liquid is increased by adding it, and examples thereof include gelatin, biogum, cellulose derivatives, guar gums, sodium alginate, and polyacrylic acid. It is done.
Examples of the biogum include xanthan gum, welan gum, and gellan gum. Examples of the cellulose derivative include cationized cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, hydroxypropyl cellulose, ethyl cellulose and the like. Examples of guar gums include guar gum, hydroxypropylated guar gum, and cationized guar gum.
Cellulose derivatives are preferred in terms of the balance that the viscosity of the pretreatment liquid is relatively high and the gelation strength is relatively low. The degree of polymerization of the cellulose derivative is preferably 500 to 2000, more preferably 800 to 1800, in that the viscosity adjustment of the pretreatment liquid is relatively easy. In particular, it is preferable to use one or more selected from the group consisting of cationized cellulose, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, and hydroxypropylcellulose.
In the present invention, the content of the viscosity adjusting agent in the pretreatment liquid is set so that the viscosity of the pretreatment liquid falls within a desired range, and is not particularly limited. It is not preferable because it is difficult to make fine adjustments. On the other hand, if the addition amount of the viscosity modifier is too large, the ink absorbability is lowered. Therefore, for example, it is preferable to use within a range of 1 to 100 parts by mass with respect to 100 parts by mass of the gelling agent.

<Surfactant>
A surfactant can be added to the pretreatment liquid for the purpose of suppressing repelling of the pretreatment liquid on the support surface, and it is preferable to add it. The addition of the surfactant can ensure coating uniformity even when the viscosity of the pretreatment liquid is increased by using a viscosity modifier.
As the surfactant, any of an anionic surfactant, a cationic surfactant, and a nonionic surfactant may be used. Examples of anionic surfactants include sulfate ester salts, sulfonate salts, phosphate ester salts, and the like. Examples of the cationic surfactant include amine salt type and quaternary ammonium salt type. Nonionic surfactants include, for example, acetylene glycols, polyethylene glycols (higher alcohol ethylene oxide adducts, fatty acid ethylene oxide adducts, alkylphenol ethylene oxide adducts, polypropylene glycol ethylene oxide adducts, higher aliphatic amines and fatty acids. Amide ethylene oxide adducts, etc.), polyhydric alcohols (glycerin and pentaerythritol fatty acid esters, sorbitol and sorbitan fatty acid esters, sucrose fatty acid esters, polyhydric alcohol ethylene oxide adducts, fatty acid alkanolamides), etc. Can be mentioned.

  Among the above surfactants, nonionic surfactants are preferred because of their high affinity with ink for ink jet printers. Furthermore, among nonionic surfactants, acetylene glycol surfactants are preferred. The acetylene glycol-based surfactant is nonionic and has a very strong polarity because oxygen atoms are bonded to adjacent carbon atoms that form an acetylenic triple bond in the molecule. Therefore, even when added in a small amount, the surface activity effect is high, and the wettability of the pretreatment liquid on the support surface can be improved. In general, a surfactant has a strong bubble forming property, which causes a problem of foaming. However, an acetylene glycol surfactant has a defoaming property and can suppress foaming.

  The acetylene glycol surfactant is a compound having an acetylene bond and an alcoholic hydroxyl group in the molecule, and among them, an addition reaction product of an alkynylene glycol compound and ethylene oxide is preferable. A particularly preferred acetylene glycol surfactant is a compound obtained by adding ethylene oxide to 2,4,7,9-tetramethyl-5-decyne-4,7-diol, and is represented by the following formula (1). A compound having a chemical structure. In particular, in the formula (1), m + n is preferably 6 or less, and m + n is more preferably 2 to 5. Although m and n are integers, the average value may of course not be an integer.

  The surfactant content in the pretreatment liquid is preferably 0.001 to 10 parts by mass with respect to 100 parts by mass of the gelling agent. If the content of the surfactant is 0.001 part by mass or more with respect to 100 parts by mass of the gelling agent, the wettability of the gelling agent-containing coating liquid (pretreatment liquid) with respect to the surface of the water-absorbent support is sufficient. Can be secured. On the other hand, if it is 10 parts by mass or less, problems such as blocking after coating and transfer to the back surface are unlikely to occur.

<Other ingredients>
Although a small amount of fine particles can be contained in the pretreatment liquid, it is preferable that the pretreatment liquid is not contained in order to enhance smoothness or glossiness. The coating amount of fine particles is preferably 1.0 g / m ² or less. When the coating amount of fine particles exceeds 1.0 g / m ² , the fine particles are easily peeled off from the support and paper dust is generated in the process. Depending on the case, it reacts with the gelling agent and the viscosity of the pretreatment liquid becomes extremely high, making it difficult to apply.

  The pretreatment liquid may appropriately contain a solvent. The pretreatment liquid is, for example, a gelling agent solution in which a gelling agent is dissolved in a solvent, a viscosity adjusting agent solution in which a viscosity adjusting agent is dissolved in a solvent, or a surfactant in which a surfactant is further dissolved in a solvent. Prepared by mixing the solutions. Examples of the solvent include water or an aqueous solvent obtained by adding a small amount of an organic solvent to water.

<Coating method>
Examples of means for applying the pretreatment liquid to the water-absorbing support include a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a rod blade coater, a lip coater, a die coater, a curtain coater, and a slide bead coater. Is mentioned.
The pretreatment liquid is preferably applied such that the coating amount of the gelling agent is 0.1 to 3.0 g / m ^{2 in} terms of solid content. If the coating amount of the gelling agent is 0.1 g / m ² or more, sufficient strength of the ink receiving layer can be secured. On the other hand, if the coating amount of the gelling agent is 3.0 g / m ² or less, excessive crosslinking of the water-soluble resin can be prevented, and the ink receiving layer can be prevented from cracking.

<Drying method>
After applying the pretreatment liquid on the water-absorbing support, it is preferable to perform a drying step in which the solvent in the coating liquid is positively removed. After drying, it may be wound up and stored. The ink-receiving layer-forming coating solution can be applied onto the pre-treatment solution without drying, but in this case, immediately after the ink-receiving layer-forming coating solution is applied, For example, when a die coater is used as a coating means for the ink-receiving layer forming coating solution, it may be difficult to perform coating appropriately because the cross-linked product tends to clog the head.

The drying method is not particularly limited, and for example, drying by hot air, drying by infrared irradiation, and the like can be applied.
In particular, in the present invention, a pretreatment liquid whose viscosity is adjusted to the above range or a pretreatment liquid containing a viscosity modifier is used. Therefore, when drying with hot air, the pretreatment liquid on the support is heated by hot air. It is difficult to be blown away, and the phenomenon that the coating surface is rippled is suppressed. Therefore, high-speed drying can be performed by increasing the hot air.
Furthermore, when borax is used as the gelling agent, by adjusting the viscosity of the pretreatment liquid to the above range, moisture retention after drying is improved, and borax crystallizes and precipitates during storage. The effect that it can suppress is also acquired.

(Formation of ink receiving layer)
In the present invention, after the pretreatment liquid is applied, an ink receiving layer forming coating liquid is applied to produce an ink jet recording sheet. The ink-receiving layer-forming coating solution contains a water-soluble resin having the ability to gel or thicken in contact with the gelling agent contained in the pretreatment liquid, and fine particles.

<Fine particles>
As fine particles, for example, amorphous silica (including synthetic amorphous silica produced by a wet method and a dry method, and cation-modified silica such as alumina), amorphous silica and a cationic compound are mixed and agglomerated. Amorphous silica-cationic compound aggregate particles obtained by making kaolin, clay, calcined clay, zinc oxide, tin oxide, titanium oxide, magnesium sulfate, aluminum hydroxide, alumina and alumina hydrate, calcium carbonate, Examples include satin white, aluminum silicate, smectite, zeolite, magnesium silicate, magnesium carbonate, magnesium oxide, diatomaceous earth, styrene plastic pigment, urea resin plastic pigment, and benzoguanamine plastic pigment. Among these, amorphous silica and an amorphous silica-cationic compound aggregate obtained by mixing and aggregating amorphous silica and a cationic compound from the viewpoint of easy balance between glossiness and ink absorbability It is preferable to use surface-modified amorphous silica, aluminosilicate, alumina, and alumina hydrate in which particles and amorphous silica are modified and coated with a cationic compound.

  Fine particles used in the ink receiving layer have an average particle size of 5 nm or more and 700 nm or less. Glossiness is excellent when the thickness is 700 nm or less, and ink absorbability is excellent when the thickness is 5 nm or more. The average particle diameter is the diameter of the primary particles when present in the coating liquid as primary particles, and the diameter of the secondary particles when present in the coating liquid as secondary particles in which primary particles are aggregated. . Adjustment of the average particle diameter (average secondary particle diameter) of the secondary particles can be performed by, for example, a method of applying a strong force by mechanical means, a so-called breaking down method (a method of subdividing a bulk material). Mechanical means include: ultrasonic homogenizer, pressure homogenizer, liquid collision homogenizer, high-speed rotary mill, roller mill, container drive medium mill, medium agitator mill, jet mill, mortar, disintegrator (covered in a bowl-shaped container) A device for grinding and kneading the pulverized product with a bowl-shaped stirring bar), a sand grinder, a nanomizer and the like. In order to reduce the particle size, classification and pulverization can be repeated.

<Water-soluble resin>
Examples of the water-soluble resin that can be gelled or thickened include, for example, polyvinyl alcohol, cation-modified polyvinyl alcohol, silyl-modified polyvinyl alcohol, polyvinyl acetal, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, casein, soy protein, synthetic proteins, and starch. , Polypropylene oxide, polyethylene glycol, polyvinyl ether, polyvinyl acrylamide, polyvinyl pyrrolidone and the like.
Among these, polyvinyl alcohol is preferable from the viewpoint of ink absorbability, water resistance, and prevention of cracks. The polyvinyl alcohol preferably has a degree of polymerization of 3000 to 5000. If the degree of polymerization is less than 3000, the resulting ink-receiving layer tends to have insufficient water resistance, and those exceeding 5000 are practically difficult to obtain.

The water-soluble resin is preferably used in the range of 1 to 100 parts by mass, more preferably 5 to 50 parts by mass with respect to 100 parts by mass of the fine particles.
The mass ratio of the water-soluble resin and the gelling agent is preferably 20: 1 to 1:20, and more preferably 10: 1 to 1:10. By setting the mass ratio within this range, an ink jet recording sheet can be obtained which is superior in crack prevention, aging resistance and ink absorbability.

<Other ingredients>
Examples of the ink-receiving layer-forming coating liquid include water-dispersible resins (for example, conjugated diene series of styrene-butadiene copolymer and methyl methacrylate-butadiene copolymer) within the scope of achieving the object of the present invention. Polymer latex, polyprenes such as isoprene, neoprene (registered trademark), polybutadiene, acrylic polymer latex, polyalkenes such as polybutene, polyisobutylene, polypropylene, polyethylene, vinyl halide, vinyl acetate, styrene, (meth) acrylic acid , (Meth) acrylic acid ester, (meth) acrylamide, vinyl polymer and copolymer latex such as methyl vinyl ether, polyurethane resin, polyester resin, polyamide resin, olefin-maleic anhydride resin, melamine Such as resin) It may generally contain various adhesives used in coated paper field.
In addition, the ink receiving layer forming coating solution may contain a cationic compound as an ink fixing agent. Examples of the cationic compound include polyalkylene polyamines such as polyethylene amine and polypropylene polyamine, or derivatives thereof, acrylic resins having a tertiary amino group or a quaternary ammonium group, and diacrylamine. As content of a cationic compound, it is preferable that it is 1-30 mass parts with respect to 100 mass parts of fine particles, and it is more preferable that it is 5-20 mass parts.
Furthermore, the coating liquid for forming an ink receiving layer may contain various auxiliary agents such as various dispersants, thickeners, antifoaming agents, colorants, antistatic agents, and preservatives.

<Coating method, drying method>
As the coating method and the drying method of the ink receiving layer forming coating liquid on the above-mentioned support, the same methods as the pretreatment liquid coating method and the drying method can be applied. Even if the ink receiving layer formed on the support is a single layer, good ink absorbability can be obtained, but it is also possible to form an ink receiving layer thereon.
The coating amount of the ink receiving layer is in the range of 5 to 50 g / m ^2. If it is less than 5 g / m ² , the ejected ink cannot be absorbed, and there is a disadvantage that the printing is smeared or smeared. ^{On the other hand, if it is} more than 50 g / m ^{2, the} resulting recording sheet not only becomes thicker, but also causes problems such as an increase in curl and a rigid bending of the sheet. The preferred range is in the range of 10 to 40 g / m ^2. If the ink receiving layer of the present invention exhibits the same function, two or more layers may be divided and applied.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples. Moreover, unless otherwise indicated, the part and% in an example are a mass part and the mass%, respectively.

(Water-absorbing support)
Beating softwood bleached kraft pulp (NBKP) until freeness (CSF, JIS P-8121) reaches 250 ml, and broadleaf bleached kraft pulp (LBKP) beaten until freeness reaches 250 ml, a mass ratio of 2: 8 Was mixed to prepare a pulp slurry having a concentration of 0.5%. In this pulp slurry, cationized starch 2.0%, alkyl ketene dimer 0.4%, anionized polyacrylamide resin 0.1%, polyamide polyamine epichlorohydrin resin 0.7%, and internal addition to the pulp dry weight. Light calcium carbonate was added as a filler and dispersed by sufficiently stirring. The amount of light calcium carbonate was adjusted to 5% in terms of the mass ratio of the finished base paper.
The pulp slurry having the above composition was made with a long net machine, and passed through a dryer, a size press, and a machine calendar to produce a base paper having a basis weight of 180 g / m ² and a density of 0.85 g / cm ³ . The size press liquid used in the size press step is prepared by mixing polyvinyl alcohol and oxidized starch at a mass ratio of 1: 3, adding this to water, dissolving by heating, and adjusting the concentration to 5%. The amount of the size press solution absorbed into the base paper was 50 ml / m ² in total on both sides.

(Silica sol A)
Commercially available vapor phase silica (trade name: Leolosil QS-30, average primary particle size 10 nm, specific surface area 300 m ² / g, manufactured by Tokuyama Corporation) was dispersed and pulverized with a sand mill, and then nanomizer (trade name: nanomizer, manufactured by Nanomizer) ) Was repeated, and after classification, a 10% silica dispersion having an average secondary particle size of 80 nm was prepared. To 100 parts of this silica dispersion, 10 parts of diallyldimethylammonium chloride (trade name: Unisense CP-103, manufactured by Senca) was added as a cationic compound to cause aggregation of silica and increase the viscosity of the dispersion. Thereafter, pulverization and dispersion were repeated using a nanomizer again to prepare an 8% dispersion having an average secondary particle size of 300 nm, whereby silica sol A was obtained.

<Example 1>
"Pretreatment liquid coating"
On the water-absorbent support, the following pretreatment liquid 1 was applied with a Mayer bar so as to be 20 g / m ² (wet), and dried at a dryer temperature of 100 ° C. for 1 minute. The coating amount at this time was 0.6 g / m ² in terms of solid content.
(Preparation of pretreatment liquid 1)
100 parts of a 5% aqueous solution of borax and 3 parts of a 1% aqueous solution of cationized cellulose (polymerization degree: 1500, trade name: Poise C-150L, manufactured by Kao Corporation) are mixed and stirred, and water is added thereto. A pretreatment liquid containing a material having a gelling or thickening action at a concentration of 3.8% and a viscosity of 5 mPas was prepared.

"Formation of ink-receiving layer"
Next, the following ink receiving layer forming coating liquid 1 was applied to the pretreatment liquid coating surface with a die coater so that the coating amount was 22 g / m ^{2 in} terms of solid content, and the dryer temperature was 100 ° C. for 2 minutes. It was dried to form an ink receiving layer.
(Preparation of coating liquid 1 for forming an ink receiving layer)
24 parts of 5% polyvinyl alcohol (trade name: PVA-135H, product name: PVA-135H, polymerization degree: 3500, saponification degree: 99% or more) manufactured by Kuraray Co., Ltd. were mixed with 100 parts of silica sol A to prepare ink-receiving layer coating material 1.

<Example 2>
"Pretreatment liquid coating"
On the water-absorbent support, the following pretreatment liquid 2 was applied with a Mayer bar so as to be 40 g / m ² and dried at a dryer temperature of 100 ° C. for 1 minute. The coating amount at this time was 0.9 g / m ² in terms of solid content.
(Preparation of pretreatment liquid 2)
100 parts of 5% aqueous borax solution, 10 parts of 1% aqueous solution of cationized cellulose (degree of polymerization: 1500, trade name: Poise C-150L, manufactured by Kao Corporation), 0.1% aqueous solution of acetylene glycol surfactant (Product name: Orphin E1004, manufactured by Nissin Chemical Industry Co., Ltd.) 2 parts were mixed and stirred to prepare a pretreatment liquid containing a material having an action of gelation or thickening at a concentration of 2.2% and a viscosity of 10 mPas.
"Formation of ink-receiving layer"
In the same manner as in Example 1, an ink receiving layer was formed.

<Example 3>
"Pretreatment liquid coating"
On the water-absorbing support, the following pretreatment liquid 3 was applied with a Mayer bar so as to be 40 g / m ² and dried at a dryer temperature of 100 ° C. for 1 minute. The coating amount at this time was 1.1 g / m ² in terms of solid content.
In the preparation of the pretreatment liquid 2 of Example 2, 100 parts of 10% borax aqueous solution heated to 60 ° C. was used instead of 100 parts of 5% borax aqueous solution.
(Preparation of pretreatment liquid 3)
100 parts of borax 10% aqueous solution (60 ° C.), 10 parts of 1% aqueous solution of cationized cellulose (degree of polymerization: 1500, trade name: Poise C-150L, manufactured by Kao Corporation), 0 of acetylene glycol surfactant A pretreatment solution containing a material having an action of gelling or thickening at a concentration of 2.8% and a viscosity of 3 mPas by mixing and stirring 2 parts of a 1% aqueous solution (trade name: Olfin E1004, manufactured by Nissin Chemical Industry Co., Ltd.) Was prepared.
"Formation of ink-receiving layer"
In the same manner as in Example 2, an ink receiving layer was formed.

<Example 4>
"Pretreatment liquid coating"
On the water-absorbing support, the following pretreatment liquid 4 was applied with a Mayer bar so as to be 40 g / m ² and dried at a dryer temperature of 100 ° C. for 1 minute. The coating amount at this time was 1.3 g / m ² in terms of solid content.
In the preparation of the pretreatment liquid 3 of Example 3, 10 parts of a 2% aqueous solution of hydroxyethyl cellulose (trade name: Sanheck H, manufactured by Sanki Co., Ltd.) was used instead of 10 parts of a 1% aqueous solution of cationized cellulose. This is an example.
(Preparation of pretreatment liquid 4)
100 parts of borax 10% aqueous solution (60 ° C.), 10 parts of 2% aqueous solution of hydroxycellulose (trade name: Sanheck H, manufactured by Sanki Co., Ltd.), 0.1% aqueous solution of acetylene glycol surfactant (trade name) : Orphin E1004 (manufactured by Nissin Chemical Industry Co., Ltd.) was mixed and stirred to prepare a pretreatment liquid containing a material having an action of gelling or thickening at a concentration of 3.2% and a viscosity of 2.4 mPas.
"Formation of ink-receiving layer"
In the same manner as in Example 2, an ink receiving layer was formed.

<Example 5>
"Pretreatment liquid coating"
On the water-absorbing support, the following pretreatment liquid 5 was applied with a Mayer bar so as to be 40 g / m ² and dried at a dryer temperature of 100 ° C. for 1 minute. The coating amount at this time was 1.3 g / m ² in terms of solid content.
In the preparation of the pretreatment liquid 3 of Example 3, 10 parts of a 2% aqueous solution of hydroxypropylmethylcellulose (trade name: 60SH-15, manufactured by Shin-Etsu Chemical Co., Ltd.) was used instead of 10 parts of a 1% aqueous solution of cationized cellulose. It is an example used.
(Preparation of pretreatment liquid 5)
100 parts of borax 10% aqueous solution (60 ° C.), 10 parts of 2% aqueous solution of hydroxypropylmethylcellulose (trade name: Metrolose 60SH-15, manufactured by Shin-Etsu Chemical Co., Ltd.), 0.1% aqueous solution of acetylene glycol surfactant (Product name: Olfin E1004, manufactured by Nissin Chemical Industry Co., Ltd.) 2 parts were mixed and dissolved to prepare a pretreatment liquid containing a material having an action of gelling or thickening with a concentration of 3.3% and a viscosity of 3 mPas.
A 2% aqueous solution of hydroxypropylmethylcellulose was prepared as follows. That is, 2 parts of hydroxypropylmethylcellulose was added to 98 parts of cold water while stirring, and after dispersion, this was heated to a liquid temperature of 95 ° C. and held for 1 hour, and then cooled to a liquid temperature of 10 ° C. A 2% aqueous hydroxypropyl methylcellulose solution was obtained.
"Formation of ink-receiving layer"
In the same manner as in Example 2, an ink receiving layer was formed.

<Example 6>
"Pretreatment liquid coating"
On the water-absorbing support, the following pretreatment liquid 6 was applied with a Mayer bar so as to be 40 g / m ² and dried at a dryer temperature of 100 ° C. for 1 minute. The coating amount at this time was 1.3 g / m ² in terms of solid content.
In addition, in preparation of the pretreatment liquid 3 of Example 3, instead of 10 parts of 1% aqueous solution of cationized cellulose, 5 parts of 2% aqueous solution of carboxymethylcellulose (trade name: Serogen WSA, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) It is an example used.
(Preparation of pretreatment liquid 6)
100 parts of borax 10% aqueous solution (60 ° C.), 10 parts by weight of 2% aqueous solution of carboxymethylcellulose (degree of polymerization: 1000, trade name: Cellogen WSA, Daiichi Kogyo Seiyaku), 0. 0% of acetylene glycol surfactant. 2 parts of 1% aqueous solution (trade name: Olfin E1004, manufactured by Nissin Chemical Industry Co., Ltd.) was mixed and dissolved to prepare a pretreatment liquid containing a material having an action of gelling or thickening with a concentration of 3.3% viscosity of 3 mPas. .
"Formation of ink-receiving layer"
In the same manner as in Example 2, an ink receiving layer was formed.

<Example 7>
"Pretreatment liquid coating"
On the water-absorbing support, the following pretreatment liquid 7 was applied with a Mayer bar so as to be 40 g / m ² and dried at a dryer temperature of 100 ° C. for 1 minute. The coating amount at this time was 1.3 g / m ² in terms of solid content.
In the preparation of the pretreatment liquid 3 of Example 3, 10 parts of a 5% aqueous solution of gelatin (trade name: P-100, manufactured by Miyagi Chemical Industry) was used instead of 10 parts of a 1% aqueous solution of cationized cellulose. It is an example.
(Preparation of pretreatment liquid 7)
100 parts of borax 10% aqueous solution (60 ° C.), 10 parts of 5% aqueous solution of gelatin (trade name: P-100, Miyagi Chemical Industry), 0.1% aqueous solution of acetylene glycol surfactant (trade name: 2 parts of Olphine E1004 (manufactured by Nissin Chemical Industry Co., Ltd.) were mixed and dissolved to prepare a pretreatment liquid containing a material having an action of gelling or thickening at a concentration of 3.3% and a viscosity of 2.4 mPas.
A 5% aqueous solution of gelatin was prepared as follows. That is, 5 parts of gelatin was added and dispersed in 95 parts of cold water with stirring, and then heated to 95 ° C. and held for 1 hour. It was then cooled to room temperature to obtain a 5% gelatin solution.
"Formation of ink-receiving layer"
In the same manner as in Example 2, an ink receiving layer was formed.

<Example 8>
"Pretreatment liquid coating"
On the water-absorbing support, the following pretreatment liquid 8 was applied with a Mayer bar so as to be 40 g / m ² and dried at a dryer temperature of 100 ° C. for 1 minute. The coating amount at this time was 1.3 g / m ² in terms of solid content.
In the preparation of the pretreatment liquid 2 in Example 2, 100 parts of a 2% aqueous solution of boric acid heated to 60 degrees was used instead of 100 parts of a 5% aqueous solution of borax.
(Preparation of pretreatment liquid 8)
100 parts of boric acid 10% aqueous solution (60 ° C.), 10 parts of 1% aqueous solution of cationized cellulose (degree of polymerization: 1500, trade name: Poise C-150L, manufactured by Kao Corporation), 0 of acetylene glycol surfactant A pretreatment solution containing a material having an action of gelling or thickening at a concentration of 3.2% and a viscosity of 2 mPas by mixing and stirring 2 parts of a 1% aqueous solution (trade name: Olfin E1004, manufactured by Nissin Chemical Industry Co., Ltd.) Adjusted.
"Formation of ink-receiving layer"
In the same manner as in Example 2, an ink receiving layer was formed.

<Example 9>
"Pretreatment liquid coating"
On the water-absorbing support, the following pretreatment liquid 9 was applied with a Mayer bar so as to be 10 g / m ² and dried at a dryer temperature of 100 ° C. for 1 minute. The coating amount at this time was 0.2 g / m ² in terms of solid content.
In Example 1, the pretreatment liquid 1 is diluted to a concentration of 2%.
(Pretreatment liquid 9)
100 parts of a 5% aqueous solution of borax and 3 parts of a 1% aqueous solution of cationized cellulose (polymerization degree: 1500, trade name: Poise C-150L, manufactured by Kao Corporation) are mixed and stirred, and water is added to this to concentrate. A pretreatment liquid containing a material having a gelling or thickening action of 2.0% and a viscosity of 2.2 Pas was prepared.
"Formation of ink-receiving layer"
In the same manner as in Example 1, an ink receiving layer was formed.

<Example 10>
"Pretreatment liquid coating"
On the water-absorbing support, the following pretreatment liquid 10 was applied with a Mayer bar so as to be 40 g / m ² and dried at a dryer temperature of 100 ° C. for 1 minute. The coating amount at this time was 0.88 g / m ² in terms of solid content.
In Example 1, the preparation concentration of the pretreatment liquid 1 is 4.5.
(Pretreatment liquid 10)
100 parts of a 5% aqueous solution of borax and 3 parts of a 1% aqueous solution of cationized cellulose (polymerization degree: 1500, trade name: Poise C-150L, manufactured by Kao Corporation) are mixed and stirred to a concentration of 4.5% and viscosity. A pretreatment liquid containing a material having a gelling or thickening action of 18 mPas was prepared.
"Formation of ink-receiving layer"
In the same manner as in Example 1, an ink receiving layer was formed.

<Example 11>
"Pretreatment liquid coating"
On the water-absorbing support, the following pretreatment liquid 11 was applied with a Mayer bar so as to be 15 g / m ² and dried at a dryer temperature of 100 ° C. for 1 minute. The coating amount at this time was 0.6 g / m ² in terms of solid content.
In addition, in the preparation of the pretreatment liquid 10 of Example 10, instead of 3 parts of 1% aqueous solution of cationized cellulose (degree of polymerization: 1500, trade name: Poise C-150L, manufactured by Kao Corporation), the molecular weight is different. This is an example using 10 parts of 3.6% aqueous solution of cationized cellulose (degree of polymerization: 600, trade name: Poise C-60H, manufactured by Kao Corporation).
(Preparation of pretreatment liquid 11)
100 parts of a 5% aqueous solution of borax and 10 parts of a 2% aqueous solution of cationized cellulose (polymerization degree: 600, trade name: Poise C-60H, manufactured by Kao Corporation) are mixed and stirred, and water is added thereto. A pretreatment liquid containing a material having a gelling or thickening action at a concentration of 3.6% and a viscosity of 3 mPas was prepared.
"Formation of ink-receiving layer"
In the same manner as in Example 1, an ink receiving layer was formed.

<Example 12>
"Pretreatment liquid coating"
On the water-absorbing support, the following pretreatment liquid 12 was applied with a Mayer bar so as to be 56 g / m ² and dried at a dryer temperature of 100 ° C. for 1 minute. The coating amount at this time was 2.8 g / m ² in terms of solid content.
In this example, the concentration of the pretreatment liquid in Example 11 is 7%.
(Preparation of pretreatment liquid 12)
100 parts of a 5% aqueous solution of borax and 10 parts of a 2% aqueous solution of cationized cellulose (polymerization degree: 600, trade name: Poise C-60H, manufactured by Kao Corporation) are mixed and stirred, and water is added thereto. A pretreatment liquid containing a material having a gelling or thickening effect at a concentration of 7.0 and a viscosity of 15 mPas was prepared.
"Formation of ink-receiving layer"
In the same manner as in Example 1, an ink receiving layer was formed.

<Comparative Example 1>
"Pretreatment liquid coating"
On the water-absorbing support, the following pretreatment liquid 13 was applied with a Mayer bar so as to be 40 g / m ² and dried at a dryer temperature of 100 ° C. for 1 minute. The coating amount at this time was 0.9 g / m ² in terms of solid content.
In addition, in the pretreatment liquid 2 of Example 2, the pretreatment liquid which does not contain cationized cellulose and acetylene glycol surfactant and consists of a 5% aqueous solution of borax is coated on a support. Except for the above, an ink jet recording sheet was obtained in the same manner as in Example 2.
(Preparation of pretreatment liquid 13)
Water was added to 100 parts of a 5% aqueous borax solution and stirred to adjust the concentration to 2.2%. The viscosity of the pretreatment liquid was 1 mPas “formation of ink receiving layer”
In the same manner as in Example 1, an ink receiving layer was formed.

<Comparative example 2>
"Pretreatment liquid coating"
On the water-absorbing support, the following pretreatment liquid 14 was applied with a Mayer bar so as to be 40 g / m ² and dried at a dryer temperature of 100 ° C. for 1 minute. The coating amount at this time was 0.9 g / m ² in terms of solid content.
In the pretreatment liquid 2 of Example 2, a cationized cellulose is not contained, and a 5% cross-linking agent-containing coating liquid composed of borax and an acetylene glycol surfactant is applied onto a support.
(Preparation of pretreatment liquid 14)
After mixing and stirring 100 parts of a 5% aqueous solution of borax and 2 parts of a 0.1% aqueous solution of acetylene glycol surfactant (trade name: Olphine E1004, manufactured by Nissin Chemical Industry Co., Ltd.), water was added to adjust the concentration to 2. Adjusted to 2%. The viscosity of the pretreatment liquid was 1 mPas.
"Formation of ink-receiving layer"
In the same manner as in Example 2, an ink receiving layer was formed.

<Comparative Example 3>
"Pretreatment liquid coating"
On the water-absorbing support, the following pretreatment liquid 15 was applied with a Mayer bar so as to be 40 g / m ² and dried at a dryer temperature of 100 ° C. for 1 minute. The viscosity of the pretreatment liquid 15 was 30 mPas. The coating amount at this time was 0.9 g / m ² in terms of solid content.
In addition, in preparation of the pretreatment liquid 2 of Example 2, it is an example with many compounding parts of the viscosity modifier of a cationized cellulose, and few compounding parts of an acetylene glycol type surfactant.

(Preparation of pretreatment liquid 15)
100 parts of 5% borax aqueous solution, 20 parts of 1% aqueous solution of cationized cellulose (degree of polymerization: 1500, trade name: Poise C-150L, manufactured by Kao Corporation), 0.1% aqueous solution of acetylene glycol surfactant (Product name: Olphine E1004, manufactured by Nissin Chemical Industry Co., Ltd.) 1.5 parts of the mixture are mixed and stirred to prepare a pretreatment liquid containing a material having a gelling or thickening action at a concentration of 2.2% and a viscosity of 35 mPas. did.
"Formation of ink-receiving layer"
In the same manner as in Example 2, an ink receiving layer was formed.

<Comparative Example 4>
"Pretreatment liquid coating"
On the water-absorbing support, the following pretreatment liquid 16 was applied with a Mayer bar so as to be 40 g / m ² and dried at a dryer temperature of 100 ° C. for 1 minute. The viscosity of the pretreatment liquid 16 was 10 mPas. The coating amount at this time was 0.3 g / m ² in terms of solid content.
In addition, in preparation of the pretreatment liquid 2 of Example 2, it is an example in which the borax is not included and the number of blended parts of the acetylene glycol surfactant is small.
(Preparation of pretreatment liquid 16)
10 parts of 1% aqueous solution of cationized cellulose (degree of polymerization: 1500, trade name: Poise C-150L, manufactured by Kao Corporation) and 0.1% aqueous solution of acetylene glycol surfactant (trade name: Olphine E1004, Sun A pretreatment liquid containing a material having an action of gelation or thickening having a concentration of 2.2% and a viscosity of 10 mPas was prepared by mixing and stirring 0.5 part of Shinsei Chemical Co., Ltd.).
"Formation of ink-receiving layer"
In the same manner as in Example 2, an ink receiving layer was formed.

<Comparative Example 5>
An ink jet recording sheet was obtained in the same manner as in Example 1 except that the ink receiving layer was formed using the ink receiving layer forming coating liquid 2 in Example 1.
In this example, an SBR emulsion was used instead of the polyvinyl alcohol used in the ink receiving layer forming coating solution 1 of Example 1.
"Formation of ink-receiving layer"
Next, the following ink receiving layer forming coating liquid 2 was applied to the pretreatment liquid coating surface with a die coater so that the coating amount was 22 g / m ^{2 in} terms of solid content, and the dryer temperature was 100 ° C. for 2 minutes. It was dried to form an ink receiving layer.
(Preparation of ink receiving layer forming coating solution 2)
10 parts of styrene-butadiene copolymer latex (trade name: OX1060, manufactured by Nippon Zeon Co., Ltd.) was mixed with 100 parts of silica sol A to prepare a coating liquid 2 for forming an ink receiving layer.

<Example 13>
"Glossy layer formation"
On the ink receiving layer of the ink jet recording sheet obtained in Example 2, the gloss developing layer coating liquid 1 described below was applied with a die coater so that the coating amount was 5 g / m ² in terms of dry weight, and gloss was obtained. An expression layer was formed.
(Preparation of coating liquid 1 for glossy layer)
100 parts of cationic colloidal silica (trade name: Snowtex AK, manufactured by Nissan Chemical Industries) and 5% polyvinyl alcohol solution (trade name: PVA-217, manufactured by Kuraray Co., Ltd., polymerization degree: 1700, saponification degree: 88% Above) 15 parts were mixed and diluted to 10% to prepare a coating solution for glossy layer.

<Evaluation method>
In the examples and comparative examples described above, the pretreatment liquid coating suitability (repellency and surface quality uniformity), the ink receiving layer forming coating liquid coating suitability (die coating suitability), and an inkjet recording sheet The ink receiving layer was cracked, 75 ° surface glossiness, ink absorptivity, printing blemishes, and printing density. The results are shown in Table 1. The viscosity of the pretreatment liquid is also shown in Table 1.

(Applicability of pretreatment liquid: repelling)
The degree of repellency of the pretreatment liquid coated on the support was visually evaluated.
A: No repelling is observed, and there is no problem with the coated surface.
○: Slight repellency is observed when the number of cistern is less than 0.5 / m ² , but there is no practical problem.
(Triangle | delta): The number of repelling is 0.5 piece / m < ² > or more and less than 1.0 piece / m < ² >, and a problem may generate | occur | produce practically.
X: The number of repels is 1.0 / m ² or more, which is problematic in practical use.

(Applicability of pretreatment liquid: uniformity of coating surface quality)
The surface quality of the pretreatment liquid coated on the support was visually evaluated.
A: A glossy and uniform coated surface is obtained, and there is no problem.
○: A uniform coated surface is obtained and there is no problem.
Δ: The coating surface is slightly rippled, and the coating is slightly uneven.
X: The coating surface is rippled and coating is not uniform or does not have a desired coating amount.

(Die coating suitability)
The die coating suitability when the ink receiving layer forming coating solution was applied was visually evaluated in the vicinity of the paint discharge portion of the die coating head.
A: In the vicinity of the surface of the die discharge part, the ink receiving layer forming coating liquid is not gelled by a material having an action of gelling or thickening, and a uniform coating is obtained and the operation is good.
◯: The ink receiving layer forming coating liquid in the vicinity of both ends of the surface of the die discharge part is slightly gelled, but there is no practical problem. (Because the die coating head discharge part and the support were close to each other due to the curling of the support, it gelled.)
Δ: The ink receiving layer forming coating solution partially gelated not only near both ends of the surface of the die discharge part, but the appearance after drying was hardly affected and there was no practical problem.
X: In the vicinity of the surface of the die discharge part, the ink receiving layer forming coating solution gels with a material having an action of gelling or thickening, and a uniform coated surface cannot be obtained and cannot be operated.

(Crack of ink receiving layer)
The degree of cracking of the ink receiving layer was visually evaluated.
(Double-circle): A crack is not seen at all.
○: Some cracks occur, but there is no practical problem.
Δ: There are slightly more cracks than ○, but there is no practical problem.
X: Cracks occur and there are practical problems.

(75 degree surface gloss)
The 75 degree glossiness of the ink receiving layer surface of the inkjet recording sheet was measured by the method described in JIS-P8142.

(Ink absorption)
Green solid printing was performed using an inkjet printer PIXUS iP4200 manufactured by Canon Inc., and the degree of ink absorption in the solid printing portion was visually evaluated. As the ink cartridge, BCI-7Bk, BCI-7C, BCI-7M, BCI-7Y and BCI-3eBk manufactured by Canon Inc. were used.
A: No unevenness is observed in the solid print part, and it is in a good state.
◯: A level at which a slight unevenness is observed in the solid print portion but hardly causes a problem.
Δ: A level in which some unevenness is seen in the solid print portion and may cause a problem when printing including a lot of solid printing.
X: Level in which unevenness is observed in the solid print portion and causes a problem.

(Printing blur)
Inkjet printer PIXUS iP4200 manufactured by Canon Inc.) performs solid printing with black, cyan, magenta, yellow, red, green, and blue adjacent to each other, and visually evaluates the degree of blurring of the color of each boundary portion. did. As the ink cartridge, BCI-7Bk, BCI-7C, BCI-7M, BCI-7Y and BCI-3eBk manufactured by Canon Inc. were used.
(Double-circle): A blurring is not seen in a boundary part but it is in a favorable state.
○: Slight blurring is seen at the boundary, but it is not a problem.
Δ: A level at which blurring is slightly observed at the boundary and may cause a problem when a delicate image is printed.
X: A level in which blurring is observed at the boundary and becomes a problem.

(Print density)
Black solid printing was performed with an ink jet printer PIXUS iP7500 (manufactured by Canon Inc.), and the black solid printing portion was measured using a Gretag Macbeth reflection densitometer (made by Gretag Macbeth, RD-19I). The numbers shown in the table are average values of five measurements. The ink cartridges used were Canon BCI-7Bk, BCI-7C, BCI-7M, BCI-7Y, BCI-7PC, BCI-7PM, BCI-7R, and BCI-7G.

Claims (4)

In a method for producing an ink jet recording sheet comprising an ink receiving layer containing fine particles having an average particle diameter of 5 nm or more and 700 nm or less on at least one layer on a water-absorbing support, a coating liquid for forming an ink receiving layer on the support. Prior to coating, the ink receiving layer forming coating solution contains a material having a function of gelling or thickening when it comes into contact with the ink receiving layer forming coating solution, and has a viscosity of 2 mPas to 20 mPas (B A method for producing an ink jet recording sheet, comprising applying a pretreatment liquid as a mold viscometer on the support. The material having an action of gelling or thickening in contact with the ink receiving layer forming coating solution is boric acid and / or borax, and the ink receiving layer forming coating solution contains polyvinyl alcohol. The method for producing an inkjet recording sheet according to claim 1, wherein The inkjet recording according to claim 1 or 2, wherein the pretreatment liquid contains at least one selected from the group consisting of cationized cellulose, carboxymethylcellulose, hydroxyethylcellulose, and hydroxypropylmethylcellulose as a viscosity modifier. Sheet manufacturing method. In a method for producing an ink jet recording sheet comprising an ink receiving layer containing fine particles having an average particle diameter of 5 nm or more and 700 nm or less on at least one layer on a water-absorbing support, a coating liquid for forming an ink receiving layer on the support. Prior to the coating, the ink receiving layer forming coating liquid contains a material having a function of gelling or thickening when it comes into contact with the ink receiving layer forming coating liquid, and as a viscosity modifier, cationized cellulose A method for producing an ink jet recording sheet, comprising applying a pretreatment liquid containing at least one selected from the group consisting of carboxymethylcellulose, hydroxyethylcellulose, and hydroxypropylmethylcellulose on the support.