JP2012171335A - Method for manufacturing inkjet recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an inkjet recording medium which is free from problems concerning ink absorptivity and glossy even if calender finish is applied.SOLUTION: The method for manufacturing the inkjet recording medium comprises steps of: forming an ink fixation layer which comprises a binder and a fine secondary particle pigment having the average particle size of 10 nm to 3 μm on a support; applying a self-emulsifying type urethane resin having particle size of 5-100 nm on the ink fixation layer; drying the applied urethane resin to form a glossy layer; and applying calender finish by a calender of 40-150°C.

Description

  The present invention relates to a method for manufacturing an ink jet recording body applied to an ink jet recording system.

  Conventionally, ink jet recording materials are roughly classified into a non-coating type having no ink fixing layer and a coating type having an ink fixing layer. Also, the coat type is roughly classified into a mat type that does not have gloss on the recording surface and a gloss type that has gloss.

  Glossy type ink jet recording materials have been actively researched and developed for recording for photographic output, and resin-coated paper (so-called resin coating) in which a thermoplastic resin such as polyethylene resin is laminated on both sides of a paper support as a support. Formed on the ink fixing layer or the ink fixing layer using the RC paper type of the recording medium utilizing the glossiness and smoothness of the RC paper, and the paper support. It can be roughly divided into cast types in which the glossy expression layer is formed by a casting method. However, since these have a quality close to that of silver salt photographs, they have only high gloss and have a gloss, but it is desired to develop a recording medium having a lower gloss than RC paper type and cast type. Yes. Furthermore, the RC paper type uses an expensive support, and the cast type slowly dries the wet ink fixing layer or gloss developing layer with a heated cast drum, thereby improving the smoothness of the cast drum. Since it is copied on the surface of the recording medium, the productivity is low, and both are high-cost recording bodies.

  As another method for producing an inkjet recording body having gloss, there is a method of forming an inkjet recording body having an ink fixing layer by supercalendering (Patent Documents 1 and 2). However, a recording body finished with a calendar (hereinafter, various calendar devices such as a super calendar and a calendar are collectively referred to as a calendar) crushes the voids of the ink fixing layer, so that sufficient ink absorptivity is not obtained ( Patent Documents 3, 4, and 5).

JP-A-55-144172 Example Japanese Unexamined Patent Publication No. 55-150395 Example JP 61-209189, page 2, lower left column JP-A-62-95285, page 2, lower left column Japanese Patent No. 2930287 [0005]

  The present invention provides a method for producing a glossy ink jet recording material that does not have a problem in ink absorbency even when a calendar finish is applied.

As a result of intensive research aimed at providing a calendar-finished inkjet recording material, the present inventors can achieve this by adopting a configuration of an ink fixing layer and a glossy layer and incorporating a specific urethane resin in the glossy layer. Was found. That is, the present invention
(1) An ink fixing layer having a fine secondary particle pigment having an average particle diameter of 10 nm to 3 μm and a binder is provided on a support, and a self-emulsifying urethane resin having a particle diameter of 5 to 100 nm is provided on the fixing layer. A method for producing an ink jet recording material, wherein a glossy layer is formed by coating and drying, and calendering is performed with a calendar at 40 ° C to 150 ° C.
(2) The method for producing an ink jet recording material according to (1), wherein the gloss layer contains a thickener.
(3) The method for producing an ink jet recording material according to (1) or (2), wherein the glossy layer contains polyvinylpyrrolidone.

  The present invention can provide a calendar-type ink jet recording material having both gloss and ink absorbability.

  As the support, a known support can be used as an ink jet recording material. However, since a calendar process is performed in the finishing step, it is preferable to use a paper support having excellent adhesion between the coating layer and the support. As the paper support, fine paper, art paper, coated paper, cast coated paper, foil paper, kraft paper, baryta paper, paperboard, impregnated paper, vapor-deposited paper, water-soluble paper, fancy paper and the like are appropriately used.

The paper support is composed mainly of wood pulp and a filler containing it if necessary.
As the wood pulp, various chemical pulps, mechanical pulps, regenerated pulps and the like can be used, and these pulps can be beaten by a beating machine in order to adjust paper strength, papermaking suitability, and the like. The beating degree (freeness) of the pulp is not particularly limited, but is generally about 250 to 550 ml (CSF: JIS P8121). In order to increase the smoothness of the paper support, it is desirable to advance the beating degree. However, it is better not to advance the beating for blurring of the paper and blurring of the recorded image caused by moisture in the ink when recording on the paper. Often results are obtained. Accordingly, the freeness is preferably about 300 to 500 ml.

The filler is blended for the purpose of imparting opacity or adjusting the ink absorbability, and calcium carbonate, calcined kaolin, silica, titanium oxide and the like can be used. In particular, the use of calcium carbonate is preferable because it provides a substrate with high whiteness and increases the glossiness of the ink jet recording material.
The content (ash content) of the filler in the paper support is preferably about 1 to 20% by mass, and if it is too much, the paper strength may be reduced. On the other hand, if the amount is small, the air permeability of the paper support deteriorates, so the preferable filler content is 7 to 20% by mass. Within this range, the smoothness, air permeability, and paper strength are balanced, and as a result, an ink jet recording material with excellent smoothness can be easily obtained.

A sizing agent, a fixing agent, a paper strength enhancer, a cationizing agent, a yield improving agent, a dye, a fluorescent brightening agent, and the like can be added to the paper support as an auxiliary agent. Furthermore, in the size press process of the paper machine, starch, polyvinyl alcohol, cationic resin and the like can be applied and impregnated to adjust the surface strength, sizing degree, and the like. The Steecht sizing degree (as 100 g / m ² paper) is preferably 1 to 200 seconds. When the sizing degree is high, the ink absorbability is lowered, and curling after printing may be remarkable. A more preferred range of sizing is 5 to 120 seconds.
The basis weight of the paper support is not particularly limited, but is about ²⁰ to 400 g / m ² . The range of 50 to 250 g / m ² is particularly preferable for printing applications. A range of 60 to 200 g / m ² is most preferred.

<Coating layer>
The present invention has an ink fixing layer containing at least a pigment and a binder as a coating layer on a support, and a glossy layer formed on the ink fixing layer. In addition, a configuration in which an undercoat layer is provided between the support and the ink fixing layer, a configuration in which a plurality of ink fixing layers are provided, a configuration in which these layers are combined, a configuration in which an arbitrary layer is provided between the layers, and the like can be given. .

[Ink fixing layer]
The ink fixing layer is a layer mainly fixing the color material in the inkjet ink, and is a coating layer containing fine secondary particle pigments having an average particle diameter of 10 nm to 3 μm, a binder, and an ink fixing agent.

(Pigment)
Examples of the pigment for the ink fixing layer include known pigments used for inkjet recording materials. For example, kaolin (containing clay), calcium carbonate, titanium oxide, zinc oxide, amorphous silica, colloidal silica, alumina, alumina hydrate, zeolite, sepiolite, smectite, synthetic smectite, magnesium silicate, magnesium carbonate, magnesium oxide, Examples include diatomaceous earth, styrene plastic pigment, hydrotalcite, urea resin plastic pigment, benzoguanamine plastic pigment, and the like.

  Among these, the present invention uses fine secondary particle pigments having an average particle diameter of 10 nm to 3 μm. By satisfying this particle size, it is excellent in the glossiness when the calendar treatment is performed, and a fine secondary particle pigment of 10 nm to 1 μm is more preferably used. Among these pigments, a pigment selected from amorphous silica, alumina, and alumina hydrate is preferable, amorphous silica is more preferable, and a primary particle diameter of 5 nm to 50 nm and a secondary particle diameter of 10 nm to 800 nm are preferred. Phase method silica is more particularly preferred.

  Since gas phase method silica exhibits anionic property, it is preferably used as silica-cationic compound aggregate particles obtained by mixing gas phase method silica and a cationic compound. In addition, when the average particle diameter of silica-cationic compound aggregate particles exceeds 3 μm, it may be pulverized and dispersed to adjust the average particle diameter to a range of 10 nm to 3 μm. If it is less than 10 nm, the ink absorbability may be lowered. If it exceeds 3 μm, the smoothness is impaired. An average particle size of 1 μm or less is preferable because the transparency of the coating layer increases and the print density increases. The aggregate particles most preferably have an average particle size in the range of 30 to 800 nm. The cationic compound and silica-cationic compound aggregate particles act as an ink fixing agent, and will be described in detail in the section of the ink fixing agent.

  The average particle diameter here is a median diameter of a particle diameter distribution measured using an apparatus based on a dynamic light scattering method, and the present inventors have described a “dynamic light scattering particle size distribution measuring apparatus LB-500”. “Type (manufactured by Horiba, Ltd.)” is used, but if the measurement principle is the same, almost the same value can be obtained even if the model of the apparatus is different.

(binder)
The binder is blended to hold the pigment on the support. As a binder, a well-known thing can be used for inkjet recording bodies, and a water-dispersed binder and a water-soluble binder can be used alone or in combination. Examples of the water-dispersed binder include styrene-butadiene copolymer resins, methyl methacrylate-butadiene copolymer conjugated diene resins, acrylic resins, and the like. These water-dispersed binders may be used alone or in combination of two or more. It is desirable to contain a vinyl acetate copolymer whose main raw material is a polyolefin resin that is easily thermally deformed as an aqueous dispersion binder.

  Examples of water-soluble binders include proteins such as casein, soybean protein, gelatin, and synthetic protein, various starches such as starch and oxidized starch, various polysaccharides such as chitin and chitosan, polyvinyl alcohol, cationic polyvinyl alcohol, and silyl-modified polyvinyl. Examples include polyvinyl alcohols containing modified polyvinyl alcohol such as alcohol, cellulose derivatives such as carboxymethylcellulose and methylcellulose, aqueous polyurethane resins, aqueous polyester resins, and the like.

  Among these binders, polyvinyl alcohol is preferably used from the viewpoint of surface strength. Polyvinyl alcohol used in the ink fixing layer has different properties depending on the saponification degree, and it is preferable to select the saponification degree according to the purpose. When polyvinyl alcohol having a saponification degree of 95% or more, more preferably 98% or more is used, the strength of the coating layer is increased, and no foaming occurs during preparation of the coating solution, resulting in extremely high workability during production. It is good. In addition, when partially saponified polyvinyl alcohol having a saponification degree of 75 to 90% is used, the coating layer has excellent flexibility and is very effective in preventing the breakage. These polyvinyl alcohols having different saponification degrees may be used alone or in combination depending on the purpose.

  Moreover, it is preferable that the polymerization degree of the said polyvinyl alcohol is 1000 or more, and it is especially preferable that it is 1500-3000. If the degree of polymerization is less than 1000, the strength of the ink fixing layer is weak, cracks are likely to occur, and paper dust may be generated during cutting. If it exceeds 3000, sufficient ink absorbability is difficult to obtain. At the same time, the solution viscosity is high, and the handling surface in adjusting the coating solution may be difficult.

  The compounding amount of the binder in the ink fixing layer is preferably 5 to 50 parts by mass and more preferably 10 to 40 parts by mass with respect to 100 parts by mass of the pigment. If the blending amount is less than 5 parts by mass, the coating film strength may not be sufficient, and if it exceeds 50 parts by mass, the ink absorbability may be impaired.

(Ink fixing agent)
The ink fixing layer preferably contains an ink fixing agent. The ink fixing agent has a function of fixing a dye pigment in the ink for ink jet recording, and thereby imparts water resistance to the printed image. A cationic compound is used for the ink fixing agent, and examples thereof include a cationic resin, a low molecular weight cationic compound, and a metal compound.

Examples of the cationic resin include (a) polyalkylene polyamines such as polyethylene polyamine and polypropylene polyamine or derivatives thereof, and (b) an acrylic polymer having a secondary or tertiary amino group or a quaternary ammonium group, Or copolymers of these acrylamides, (c) polyvinylamines and polyvinylamidines, (d) dicyanic cationic compounds represented by dicyandiamide-formalin copolymers, (e) dicyandiamide-polyethyleneamine copolymers Polyamine cationic compounds, (he) epichlorohydrin-dimethylamine copolymer, (to) diallyldimethylammonium-SO ₂ polycondensate, (thi) diallylamine salt-SO ₂ polycondensate, (li) diallyldimethylammonium Chloride heavy , (Nu) allylamine salt copolymer, (le) dialkylaminoethyl (meth) acrylate quaternary salt copolymer, (e) acrylamide-diallylamine copolymer, (wa) a cation having a 5-membered ring amidine structure Resin etc. are mentioned.

  Examples of the low molecular weight cationic compound include silane-based, titanate-based, aluminum-based, and zirconium-based cationic coupling agents and cationic surfactants. Examples of metal compounds include water-soluble aluminum compounds (for example, aluminum chloride or hydrates thereof, aluminum sulfate or hydrates thereof, inorganic salts such as ammonium alum, polyaluminum hydroxide compounds that are inorganic aluminum-containing cationic polymers, etc. ), Water-soluble zirconium compounds (eg, zirconium acetate, zirconium chloride, zirconium oxychloride, zirconium zirconium chloride, zirconium nitrate, basic zirconium carbonate, zirconium hydroxide, zirconium carbonate / ammonium, zirconium carbonate / potassium, zirconium sulfate, fluoride) Zirconium compounds, etc.), water-soluble titanium compounds (eg, titanium chloride, titanium sulfate, etc.), water-soluble lanthanoid compounds (eg, cerium chloride, cerium nitrate, cerium sulfate, cerium acetate) Arm, and the like water-soluble polyvalent metal salt such as lanthanum nitrate, etc.). These ink fixing agents are used alone or in combination of two or more.

(Silica-cationic compound aggregate fine particles)
The cationic compound aggregates with the gas phase method silica in a mixed solution with the gas phase method silica to form a silica-cationic compound aggregate. For this reason, this cationic compound is preferably used in the form of agglomerates with vapor-phase process silica in advance rather than being used alone. The single-phase vapor phase silica used for forming the silica-cationic compound aggregated fine particles is a primary particle having an average particle diameter of 3 to 40 nm. The aggregated fine particles are substantially composed of primary particles. It consists of secondary particles formed by agglomeration. The silica-cationic compound aggregate is preferably pulverized and dispersed so as to have an average particle diameter of 0.01 to 1 μm, and used as a silica-cationic compound aggregate fine particle in the coating solution for the ink fixing layer. Examples of the pulverizing / dispersing method include ultrasonic waves, high-speed rotating mills, roller mills, container drive medium mills, medium stirring mills, jet mills, crackers, sand grinders, nanomizers (trade names), homomixers, and the like.

  The silica-cationic compound aggregated fine particles as a pigment and an ink fixing agent are used singly or in combination of two or more. By using this, the transparency, surface strength, smoothness of the ink fixing layer is used. As well as ink absorbency, color developability, weather resistance, water resistance, and the like.

(Other components of the ink fixing layer)
The inclusion of polyethylene wax in the ink fixing layer is preferable because it has the effect of increasing the printing density. Probably, the polyethylene wax is considered to have a high print density because it has hydrophobicity in the ink fixing layer or can prevent the sinking of the ink. However, since excessive use tends to impair ink absorbability, about 5 to 30 parts by mass, preferably about 10 to 20 parts by mass, are added to 100 parts of silica-cationic compound aggregate particles of the ink fixing layer. Good.

Further, various auxiliary agents such as a dispersant, a thickener, an antifoaming agent, an antistatic agent, and an antiseptic used in the production of general coated paper are appropriately added to the ink fixing layer. Further, a fluorescent dye and a colorant can be added to the ink fixing layer. Xanthan gum is preferably used as the thickener in order to suppress ink penetration.

  In the ink fixing layer, a single cationic compound may be blended in order to further improve the ink fixing property and improve the water resistance. Examples of the cationic compound include those used in the silica-cationic compound aggregate, and among these, water-soluble resins or emulsions are preferably used. In addition, a cationic compound, particularly a cationic resin, blended as a simple substance is often used when a role as an adhesive is also given.

  In order to increase the ink absorptivity of the ink fixing layer, it is preferable to suppress the binder component as much as possible. However, if the binder component is small, the coating liquid is applied when the coating liquid is applied to form the ink fixing layer. Cracks are likely to occur in the construction layer. The ink fixing layer of the present invention may have cracks, but when the cracks impair the quality of the recording medium, for example, the coating layer is thickened or gelled in the initial stage of drying to generate hot air during drying. The crack of the coating layer by can be prevented.

  The method for thickening or gelling the coating layer is not particularly limited. For example, the method for thickening or gelating using a crosslinking agent capable of crosslinking reaction with a water-soluble binder blended in the coating liquid. , A method of thickening or gelling by supplying energy such as an electron beam (for example, disclosed in JP-A-2002-160439), as a water-soluble binder, having a high temperature sensitivity that exhibits hydrophilicity and hydrophobicity depending on temperature conditions Examples thereof include a method of increasing the viscosity or gelation by changing the temperature using a molecular compound (for example, disclosed in JP-A-2003-40916). Among these, the method using a crosslinking agent is preferable because it does not require a special apparatus or compound, and will be described below as a representative example.

  Various known crosslinking agents and gelling agents can be used as the compound having crosslinkability with the binder. Examples of the compound having a crosslinking property to polyvinyl alcohol include aldehyde-based crosslinking agents such as glyoxal, epoxy-based crosslinking agents such as ethylene glycol diglycidyl ether, vinyl-based crosslinking agents such as bisvinylsulfonylmethyl ether, boric acid and borax. Examples include boron-containing compounds, glycidyl compounds, zirconium compounds, aluminum compounds, chromium compounds and the like. Among these, a boron-containing compound is particularly preferable because thickening or gelation occurs quickly.

The boron-containing compound is an oxygen acid having a boron atom as a central atom and a salt thereof. Specific examples include orthoboric acid, metaboric acid, hypoboric acid, tetraboric acid, pentaboric acid, and sodium salts, potassium salts, and ammonium salts thereof. Among these, orthoboric acid and disodium tetraborate are preferably used because they have an effect of appropriately thickening the paint.
Although content of a boron compound is based also on the polymerization degree of a boron compound and polyvinyl alcohol, it is preferable to contain 0.01-2.0 g / m < ² > on the single side | surface of a base material. When the content is 2.0 g / m ² or less, the crosslinking density with the hydrophilic binder does not become too high, and the coating strength can be improved. On the other hand, when the content is 0.01 g / m ² or more, the crosslinking with the hydrophilic adhesive is strengthened, the gelation of the coating is promoted, and the coating film is hardly cracked.

  In the ink fixing layer, for example, a cross-linking agent is applied and impregnated in advance on the surface of the base paper or the undercoat layer described later, and the ink fixing layer coating liquid is applied, or the cross-linking agent is applied to the ink fixing layer coating liquid. Is prepared and applied, or after the application of the ink fixing layer coating liquid, the crosslinking agent is applied. Among them, it is preferable to apply a crosslinking agent in advance because thickening or gelation can be caused uniformly.

The dry solid coating amount of the ink-fixing layer, but is not limited, it is preferable that generally is 2~100g / ^{m 2,} and more preferably 5 to 50 g / ^{m 2.} When the coating amount is 2 g / m ² or more, the ink absorbency in a high-definition and high-speed printer is sufficient, and when the coating amount is 50 g / m ² or less, the coating film is less likely to crack. Become.

Two or more ink fixing layers can be formed. When the ink fixing layer is formed of two or more layers as described above, the silica and the adhesive constituting each layer may be the same or different.
In addition, two or more types of silica and adhesive may be mixed in the same layer, or a combination thereof may be used.
Examples of the coating apparatus for forming the ink fixing layer include various coating apparatuses such as blade coaters, air knife coaters, roll coaters, bar coaters, gravure coaters, rod blade coaters, lip coaters, curtain coaters, and die coaters. It is done.

Also, a plurality of ink fixing layers can be applied simultaneously using a slide bead coater or the like. When two or more ink fixing layers are applied, it is preferable to use a method in which the upper layer is applied onto the lower layer while the lower layer is not dried, that is, a wet-on-wet method.
Further, the coated ink fixing layer may be subjected to a smoothing process such as super calendering or brushing as necessary.
(Undercoat layer)
The undercoat layer can be provided for the purpose of supplementing the function of the ink fixing layer. For example, by providing an undercoat layer for the purpose of absorbing the ink solvent, it is possible to quickly separate the colored component and the solvent component of the ink. For example, by providing an undercoat layer for the purpose of preventing the ink solvent from penetrating into the substrate, cockling due to the ink solvent penetrating into the paper substrate can be prevented. Of course, an undercoat layer that absorbs the ink solvent may be laminated on the undercoat layer that does not allow the ink solvent to penetrate into the substrate.

  Both of the undercoat layers are coating layers containing a pigment and a binder. Examples of pigments include kaolin (containing clay), mica, calcium carbonate, titanium oxide, zinc oxide, amorphous silica (containing colloidal silica), aluminum oxide, zeolite, sepiolite, smectite, synthetic smectite, magnesium silicate, magnesium carbonate, and oxidation. Magnesium, diatomaceous earth, styrene plastic pigment, hydrotalcite, urea resin plastic pigment, benzoguanamine plastic pigment and the like can be mentioned, and these can be used alone or in combination. As the binder, a known binder for inkjet recording materials can be used, and a water-dispersed binder and a water-soluble binder can be used alone or in combination.

In the case of the undercoat layer for the purpose of absorbing the ink solvent, it is preferable to use amorphous silica, aluminum oxide, aluminosilicate, or calcium carbonate as the pigment, and it is particularly preferable to use wet method silica. Although it does not specifically limit about a binder, Since the absorptivity of an ink solvent will be impaired when it uses excessively, it is about 7-50 mass parts with respect to 100 mass parts of pigments.
On the other hand, in the case of an undercoat layer for the purpose of preventing the ink solvent from penetrating into the substrate, it is preferable to use mica, kaolin (containing clay), calcium carbonate, smectite, synthetic smectite, etc. as the pigment. ) Is preferably used. As the binder, it is preferable to use a water-dispersed binder because the effect of suppressing the penetration of the ink solvent is high, and is preferably about 50 to 500 parts by mass with respect to 100 parts by mass of the pigment.

Further, various auxiliary agents such as a dispersant, a thickener, an antifoaming agent, an antistatic agent, and an antiseptic used in the production of general coated paper are appropriately added to the undercoat layer. Further, a fluorescent dye and a colorant can be added to the undercoat layer. Further, a crosslinking agent can be blended in order to prevent cracking of the ink fixing layer.
Examples of the coating apparatus for forming the undercoat layer include various coating apparatuses such as a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a rod blade coater, a lip coater, a curtain coater, and a die coater. .

[Glossy layer]
In the present invention, a gloss layer containing a self-emulsifying urethane resin is provided on the ink fixing layer. The self-emulsifying type urethane resin is a urethane resin produced without using an emulsifier, and a resin having a particle diameter of 5 to 100 nm is used. Such urethane resins include, for example, Elastron BN series, Elastron series, Superflex series (above, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Plus Coat series (manufactured by Kanayo Chemical Co., Ltd.), Hydran series (manufactured by DIC), etc. Has been commercialized. The particle diameter is the median diameter of the particle size distribution measured using an apparatus based on the dynamic light scattering method. The present inventors have described that “dynamic light scattering type particle size distribution measuring apparatus LB-500 (stock) The value obtained by “Horiba Seisakusho” is set to 5 nm or more to prevent the ink absorbability from being impaired, and to 100 nm or less to prevent a decrease in glossiness and recording density. A preferable particle diameter is 6 to 50 nm, and a more preferable particle diameter is 7 to 25 nm. The standard of the molecular weight of the urethane resin is 5000 or less.

(Pigment)
The glossy layer produces an effect without blending a pigment, but it is desirable to use colloidal particles when blending a pigment to improve absorption or to prevent blocking to the supercalender. . The colloidal particles of the gloss layer refer to inorganic particles or organic particles suspended and dispersed in water to form a colloidal shape. By containing the colloidal particles, uniform and high gloss can be obtained. Examples of the colloidal particles include alumina sols such as colloidal silica, boehmite, and pseudoboehmite, colloidal alumina, cationic aluminum oxides or hydrates thereof, or colloids disclosed in Japanese Patent Publication No. 47-26959. Inorganic particles such as alumina-coated particles on the surface of silica particles, polystyrene, methyl methacrylate, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, acrylic acid ester and methacrylic acid ester copolymer, microcapsules, urea resin And organic particles such as melamine. Preferred colloidal particles in the present invention include those obtained by dispersing and crushing colloidal silica or amorphous silica in the presence of a water-soluble compound capable of forming a protective colloid. Amorphous silica is preferably precipitated silica or vapor phase silica, which has a large primary particle size and is easy to crush rather than gel silica, which has a small primary particle size and a large secondary particle size and is difficult to crush. Vapor phase silica having a small particle size is more preferred. These colloidal particles can be used in combination of two or more.

(binder)
The gloss layer contains a binder for the purpose of fixing colloidal particles and the like on the ink fixing layer. The binder is selected from the above-mentioned binders used in the ink fixing layer, and may be used alone or in combination of two or more. In the glossy layer, substances contained in the fixing layer may be extracted and dissolved during operation. When the fixing layer contains a substance such as boric acid or borax, or when these substances provided below the fixing layer are mixed, they may be mixed into the glossy layer. In this sense, an acrylic resin or a urethane resin is preferable because the binder contained in the gloss layer is less reactive with a boron compound than polyvinyl alcohol or the like.

The present invention is characterized by blending fine particles of a self-emulsifying type urethane resin in order to make it easy to give gloss by calendar finishing. Further, it is desirable to contain a thickener in order to prevent the gloss layer coating liquid from penetrating into the fixing layer. Furthermore, it is desirable to contain polyvinyl pyrrolidone in order to give gloss.
When the colloidal particles in the glossy layer are cationic or when an ink fixing agent is blended in the glossy layer, it is necessary to use cationic polyacrylamide, gelatin, or a cation-modified binder.

  The amount of the binder used in the present invention is adjusted in the range of 1 to 500 parts by weight, more preferably 10 to 400 parts by weight with respect to 100 parts by weight of the colloidal particles when the colloidal particles are blended. If the blending amount of the binder is less than 1 part by mass, the adhesion of the gloss layer becomes weak and the coating layer may be lost. If it exceeds 500 parts by mass, the ink absorptivity decreases and the desired inkjet There is a possibility that the recording suitability cannot be obtained, which is not preferable.

(Other additives)
In addition, for this glossy layer, an ink fixing agent, a dispersant, a cross-linking agent, a thickener (fluid modifier), an antifoaming agent, a water-resistant agent (printability improver), an antistatic agent, an antiseptic, as necessary Various additives such as an agent, an ultraviolet absorber, a preservability improving agent, a fluorescent brightening agent, and a coloring agent can be appropriately added.
When applying the coating liquid for the gloss layer, various known coating methods can be employed. For example, a coating device such as a blade, a brush coater, a chamber coater, a bar coater, or a gravure coater is appropriately used. It is good to use.
The dry coating amount of the gloss layer is preferably about 0.1 to 5 g / m ² from the balance of ink absorbability and gloss development. Excessive coating impairs ink absorbability, and glossiness cannot be obtained without coating.

<Calendar processing>
In the present invention, after the gloss layer is formed, calendar finishing is performed in a state where the surface temperature of the calendar is 40 ° C to 150 ° C. More preferably, it is 50 degreeC-100 degreeC. When the surface temperature of the calendar is low, the gloss does not appear. When the surface temperature of the calendar is high, the coating layer is formed, the surface porosity is lowered, and the ink absorption rate is lowered.

  Here, the calendar is such that the coated layer surface hits a heated roll of metal or the like having a mirror surface (smooth surface), passes the paper between other rolls, and applies pressure to calendar. It shows that. At this time, a roll having elasticity is usually used as the other roll, but a metal roll or the like may be used. The sheet passing may be one nip or a plurality of nips of two or more nips. As the metal roll, a roll made of steel or the like plated with nickel, chromium or the like is usually used. The surface is polished to have a specular gloss. As an elastic roll, a roll made of fibers such as wool, cotton, pulp and the like as a raw material, and then a roll made by polishing by applying high pressure into an iron core, a synthetic resin roll such as urethane resin, epoxy resin, polyimide resin, Examples include an aramid fiber roll. The hardness of the elastic roll is generally 70 to 100 (short hardness D or ASTM D2240 Type D). The linear pressure between the nip of the mirror roll and the rubber roll of the thermal calendar is 10 kg / cm 2 to 200 kg / cm 2, preferably 10 kg / cm 2 to 150 kg / cm 2. If the linear pressure between the nips is low, a higher gloss cannot be obtained. Conversely, if the linear pressure is too high, the gloss is lowered and the coating layer is crushed and the ink absorbency is lowered. The coated surface is adjusted so that the 60 ° glossiness (JIS-Z8741) is 20% or more and 50% or less, preferably 25% or more and 45% or less.

  In the present invention, since the fine secondary particle pigment used in the ink fixing layer is fine, the smoothness and transparency of the ink fixing layer are increased, and the color of the ink retained in the ink fixing layer is increased in transparency. It is not hindered by the fixing layer, and as a result, the print density seems to be improved. In addition, since the gloss layer contains a self-emulsifying urethane resin having a small particle size as a main component, gloss is developed by calendering. This resin has a low molecular weight (about 3,000) and has a low film-forming property at temperatures of about 150 ° C. or less, and therefore, it hardly inhibits ink absorbability compared to other resins.

  Furthermore, by incorporating a xanthan gum thickener having a large thickening effect into the glossy layer, it is possible to suppress the penetration into the ink fixing layer and not impair the glossy effect. In the thermal calendar process in which the pressurizing process is performed under a high temperature condition, both the desired glossiness and ink absorbability can be obtained by the heating process of the thermal calendar. Furthermore, since the secondary particle diameter of the silica fine particles used in the ink fixing layer is sufficiently small, an ink jet recording material with even better smoothness and specularity can be obtained when the blurring of the paper surface layer is eliminated by calendering. It will be. In order to further improve the glossiness, it is desirable to use casein or polyvinylpyrrolidone in combination.

  The back side of the paper support (the side on which the coating layer and ink receiving layer are not formed) is provided with a coat layer and a laminate layer to correct the curl to the front side. Polyolefin to give a silver salt photograph texture It is preferable to provide a back surface layer such as a resin laminate layer. Further, the back surface may be further treated with an antistatic agent, an antiblocking agent or the like for a transportability improving process, an antistatic process, or an antiblocking process. Although the back surface can be treated before or after forming the ink receiving layer, it is preferable to treat the back surface before forming the ink receiving layer because the ink receiving layer is less likely to be damaged.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. Moreover, unless otherwise indicated, the part and% in an example are the part and% of solid content except water, and show a weight part and weight%, respectively.

Example 1
[Manufacture of paper support]
“Forming paper substrates”
In a pulp slurry consisting of 90 parts of LBKP (freeness 440 ml / csf) and 10 parts of NBKP (freeness 510 ml / csf), light calcium carbonate was added as a filler to the pulp solids so as to be 10% as paper ash, Furthermore, 0.05% of AKD sizing agent (trade name: Size Pine K-902, manufactured by Arakawa Chemical Industry Co., Ltd.) and 0.5% of aluminum sulfate were added as internal sizing agents to prepare a paper stock. Using the stock thus prepared, paper was made and dried with a hybrid type twin wire paper machine to obtain a paper (base paper). Subsequently, a 6% -concentrated oxidized starch paste (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.) is converted into a double-sided solid content through a two-roll size press device on both sides of the base paper thus obtained. It was applied and dried so as to be 1.4 g / m ² to obtain a paper base material having a basis weight of 117 g / m ² .

[Manufacture of inkjet recording medium]
"Preparation of silica fine particle dispersion"
Gas phase method silica having an average particle size of 1.0 μm (manufactured by Nippon Aerosil Co., Ltd., trade name: Aerosil A200, average primary particle size: about 12 nm) was dispersed by a homomixer, and then the average secondary particle size was set to 800 nm. A 20% by mass silica fine particle dispersion was prepared by pulverizing and dispersing with a high-speed collision type homogenizer.

"Treatment with cationic compounds"
To 100 parts by mass of this silica fine particle dispersion, 6 parts by mass of dimethyldiallylammonium chloride homopolymer (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Charol DC902P, molecular weight: 9000) is added, and a high-speed flow collision type homogenizer is used. Further, a 20% by mass cationic polymer-silica composite particle dispersion having an average secondary particle size of 0.15 μm was prepared.

"Preparation of coating solution for ink receiving layer"
As a fine pigment, 100 parts by mass (solid content) of the above cationic polymer-silica composite particle dispersion, polyvinyl alcohol having a polymerization degree of 1700 and a saponification degree of 98.0% as a binder (trade name: Kuraray Poval, manufactured by Kuraray Co., Ltd.) 15 parts by mass of PVA117), 30 parts by mass of polyethylene wax (manufactured by Meisei Chemical Co., Ltd., trade name: Meikatex PEC270, melting point 90 ° C.), 0.05 parts by mass of dispersant (manufactured by Toagosei Co., Ltd., trade name: Aron SD-10) Were mixed in water to prepare an aqueous dispersion (concentration: 20% by mass).

"Preparation of gloss layer coating solution"
Water based water-based urethane resin (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Elastron BN-27, particle size 8 nm) 80 parts by mass, colloidal silica (Grace Japan, trade name: Ludox AS-40 22 nm) 20 parts by mass , 20 parts of an anionic acrylic silicone emulsion (Daicel Chemical Industries, Ltd., trade name: Aquabrid 4635) and 7 parts by weight of xanthan gum (trade name: Road Pole 23, manufactured by Rhodia Nikka Co., Ltd.) A concentration of 3% by mass) was prepared.

"Formation of ink-receiving layer"
The ink receiving layer coating liquid having the above composition is applied to the coating layer surface of the paper support using a Mayer bar, dried with a dryer, and then the gloss layer coating liquid is applied to the Mayer bar. Using a calender device consisting of a metal roll and a resin roll under the conditions shown below, calendering is performed at one nip so that the ink fixing layer is in contact with the metal roll. Then, an ink jet recording material of Example 1 was produced. The dry coating amount of the ink receiving layer was 5 g / m ² , and the dry coating amount of the glossy layer was 0.5 g / m ² .

[Calendar condition]
Metal roll surface temperature: 60 ° C
Rubber roll surface hardness: Hsd98
Linear pressure: 90kg / cm
Speed: 20m / min
Number of nips: 2 times

Example 2
In the preparation of the coating solution for the glossy layer, an aqueous urethane resin (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Elastron) was used instead of the aqueous urethane resin (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Elastron BN-27). An ink jet recording material was obtained in the same manner as in Example 1 except that BN-77 and a particle diameter of 16 nm were used.

Example 3
In the preparation of the coating solution for the glossy layer, an aqueous urethane resin (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Elastron) was used instead of the aqueous urethane resin (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Elastron BN-27). An ink jet recording material was obtained in the same manner as in Example 1 except that BN-04 was used.

Example 4
An inkjet recording material was obtained in the same manner as in Example 1 except that 5 parts by mass of polyvinyl pyrrolidone (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Pitzkor K90) was added in the preparation of the gloss layer coating solution. .

Example 5
Inkjet recording was performed in the same manner as in Example 1 except that the number of parts of colloidal silica (product name: Ludox AS-40 22 nm) was changed from 20 parts by mass to 0 parts by mass in the preparation of the coating liquid for the glossy layer. A record was obtained.

Example 6
An ink jet recording material was obtained in the same manner as in Example 1 except that the calendar temperature was 140 ° C. in the formation of the ink receiving layer.

Example 7
In the preparation of the ink receiving layer coating liquid, the cationic polymer silica having an average secondary particle diameter of 1.2 μm (produced by Grace Japan Co., Ltd.) was used instead of the cationic polymer-silica composite particle dispersion of Example 1. An ink jet recording material was obtained in the same manner as in Example 1 except that the product name: Silojet 712C) was used.

Comparative Example 1
In the preparation of the coating solution for the glossy layer, an aqueous urethane resin (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Elastron) was used instead of the aqueous urethane resin (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Elastron BN-27). An ink jet recording material was obtained in the same manner as in Example 1 except that BN-69 and a particle size of 247 nm were used.

Comparative Example 2
In the preparation of the gloss layer coating solution, acrylic resin (manufactured by Daicel Kogyo Co., Ltd., trade name: Aquabrid 4635, particles) instead of water-based urethane resin (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Elastron BN-27) An ink jet recording material was obtained in the same manner as in Example 1 except that the diameter was changed to 20 nm.

Comparative Example 3
In the preparation of the ink receiving layer coating solution, 6 parts by mass of dimethylallyl ammonium chloride homopolymer (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Charol DC902P, molecular weight: 9000) with respect to 100 parts by mass of Fine Seal X-45. A 20 mass% cationic polymer-silica composite particle dispersion having an average secondary particle diameter of 4.5 μm was prepared. An ink jet recording material was obtained in the same manner as in Example 1 except that this cationic polymer-silica composite particle dispersion was used.

Comparative Example 4
In the preparation of the coating solution for the gloss layer, polyethylene wax (trade name: Nopcoat PEM-17, manufactured by San Nopco Co., Ltd.) is used instead of the water-based urethane resin (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Elastron BN-27). Except that, an ink jet recording material was obtained in the same manner as in Example 1.

Comparative Example 5
An ink jet recording material was obtained in the same manner as in Example 2 except that the surface temperature of the metal roll was 160 ° C. under the calendar conditions.

Comparative Example 6
An ink jet recording material was obtained in the same manner as in Example 2 except that the surface temperature of the metal roll was 30 ° C. under the calendar conditions.

[Evaluation methods]
Each physical property was measured by the following method.

"Measurement of 60 ° gloss"
According to JIS-Z8741, the glossiness of the ink jet recording material was measured under the conditions of an incident angle and a light receiving angle of 60 degrees. The measuring instrument used was GLOSS METER MODEL GM-26D manufactured by Murakami Color Research Laboratory. The above measurement results are shown in Table 1.

"Measurement of particle size"
It measured by HORIBA LB-500.

"Print density"
The obtained ink jet recording material was output by each printer, and the color density of the image was evaluated by the method shown below. For evaluation, dye ink jet printer (manufactured by HP, trademark: C309g, printing mode: photo / everyday photo paper (semi-gloss) / standard mode), (manufactured by EPSON, trademark: EP-802A, printing mode: photo gloss) Paper (standard / automatic mode) and (Canon, trademark: MP640, printing mode: photographic paper / gloss / standard / automatic mode) were used. The evaluation results are shown in Table 1.

  The present invention makes it possible to achieve both gloss and ink jet recording suitability that could not be achieved by a calendar finishing method. Compared to the casting method and the like, the production efficiency is good and the production can be made at a low cost. Therefore, it can be widely used as an output medium for inkjets from home use to industrial use.

Claims (3)

An ink fixing layer having a fine secondary particle pigment having an average particle diameter of 10 nm to 3 μm and a binder is provided on a support, and a self-emulsifying urethane resin having a particle diameter of 5 to 100 nm is applied to the fixing layer and dried. Forming a glossy layer and calendering with a calendar at 40 ° C. to 150 ° C. The method for producing an ink jet recording material according to claim 1, wherein the glossy layer contains a thickener. The method for producing an ink jet recording material according to claim 1, wherein the glossy layer contains polyvinylpyrrolidone.