JP2012111158A - Inkjet recording medium, and method for manufacturing the same - Google Patents

Abstract

Provided is a glossy ink jet recording material that does not have a problem in ink absorbency even when subjected to calendar finishing.
In an inkjet recording body having an ink fixing layer containing at least a pigment, a binder, and an ink fixing agent on a support, polyvinyl alcohol and a thermosensitive aqueous adhesive are contained as a binder of the ink fixing layer, and The ink jet recording material is an ink jet recording material that is processed by a calendar.
[Selection figure] None

Description

  The present invention relates to a recording material 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 the copy is made on the surface of the recording medium, the productivity is low and both of them are high manufacturing costs.

  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, since a recording body finished by a calendar (hereinafter, various calendar devices such as a super calendar and a calendar are collectively referred to as a calendar) crushes voids in the ink fixing layer, 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 glossy ink jet recording material that does not have a problem in ink absorbability even when a calendar finish is applied.

  As a result of intensive studies to provide a calendar-finished inkjet recording body, the present inventors have found that it can be achieved by using polyvinyl alcohol and a heat-sensitive aqueous adhesive in combination as a binder for the ink fixing layer. . The present invention is as follows.

(1) In an inkjet recording body having an ink fixing layer containing at least a pigment, a binder, and an ink fixing agent on a support, polyvinyl alcohol and a thermosensitive aqueous adhesive are contained as a binder of the ink fixing layer; and The ink jet recording material is an ink jet recording material that is processed by a calendar.
(2) The ink fixing layer is the ink jet recording material according to (1), wherein 10 to 4850 parts by mass of the heat-sensitive aqueous adhesive is contained with respect to 100 parts by mass of the pigment.
(3) The ink recording layer according to (1) or (2), wherein the ink fixing layer contains gas phase method silica as a pigment.
(4) The ink jet recording material according to any one of (1) to (3), wherein the heat-sensitive water-based adhesive is an adhesive mainly composed of a polyolefin-vinyl acetate copolymer.
(5) The ink jet recording material according to any one of (1) to (4), wherein the ink fixing layer contains polyethylene wax.
(6) An ink jet recording medium comprising: an ink fixing layer containing at least one pigment, a heat-sensitive aqueous adhesive as a binder, and an ink fixing agent on a support; It is a manufacturing method.
(7) The method for producing an ink jet recording material according to (6), wherein an ink fixing layer is provided, an outermost layer is provided, and then a calendar process is performed.

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

<Support>
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, craft paper, baryta paper, paperboard, impregnated paper, vapor-deposited paper, water-soluble paper, and the like are used as appropriate.

  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, when recording on the paper, it is better not to advance the beating for blurring of the paper caused by moisture in the ink and bleeding of the recorded image. Often get. 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.
Although the basic weight of a base material is not specifically limited, It is about 20-400 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, a binder, and an ink fixing agent as a coating layer on a support. When the coating layer is a single layer, the ink fixing layer is the outermost layer.
When there are a plurality of coating layers, a configuration in which the outermost layer is provided on the ink fixing layer, 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, or further these layers The structure which combined these, the structure which provided arbitrary layers between each layer, etc. are mentioned.

[Ink fixing layer]
The ink fixing layer is a layer that mainly fixes the color material in the inkjet ink, and is a coating layer containing a pigment, a binder, and an ink fixing agent.

(Pigment)
As the pigment of the ink fixing layer, known pigments used for inkjet recording materials can be used. 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, fine secondary particle pigments having an average particle diameter of 10 nm to 3 μm are excellent in gloss when calendered, and fine secondary particle pigments of 10 nm to 1 μm are more preferably used. Among these pigments, a pigment selected from amorphous silica, alumina, and alumina hydrate is preferable, amorphous silica is more preferable, and the primary particle diameter is 5 nm to 50 nm, and the secondary particle diameter is 10 nm to 300 nm. 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. In the present invention, polyvinyl alcohol and a heat-sensitive aqueous adhesive are used in combination as a binder.

  As the heat-sensitive aqueous adhesive, known ones can be used, for example, ethylene-vinyl acetate copolymer resin, polyester resin, ethylene-acrylic acid copolymer resin, ethylene-ethyl acrylate copolymer resin, polyurethane resin, polyamide resin. And vinyl acetate resin. Among these, the use of a cationic heat-sensitive aqueous adhesive is preferable, and an adhesive mainly composed of a polyolefin-vinyl acetate copolymer is preferable as a component.

  Since heat-sensitive water-based adhesives have the property of being easily deformed by heat, when they are included in the ink fixing layer, the surface of the coating layer is efficiently smoothed by the heat and pressure at the time of calendering, and gloss is obtained. Can do. Gloss tends to improve when the surface drum temperature of the calender to be processed is higher than the MFT (minimum film forming temperature) of the heat-sensitive water-based adhesive, but if the surface drum temperature is too high, the ink absorbability decreases due to film formation. There is a risk of it. Moreover, it is preferable that the particle diameter of a thermosensitive aqueous adhesive is 0.5-2.0 micrometers. When the particle diameter is 0.5 μm or more, the adhesiveness is improved, and when the particle diameter is 2.0 μm or less, the transparency is increased and the printing density can be prevented from being lowered. The preferred MFT of the thermosensitive aqueous adhesive is 0 to 90 ° C, more preferably 0 to 60 ° C.

  The heat-sensitive water-based adhesive is used as a heat-seal adhesive, and is usually heated to form a film so that the adhesion is sufficient. In the ink fixing layer of the present invention, the heat-sensitive water-based adhesive is Since it is used in a state where the film is not sufficiently formed, the surface strength of the ink fixing layer is insufficient. If a large amount of a heat-sensitive water-based adhesive is added to increase the strength, the ink absorbability is lowered. The present invention can compensate for the lack of surface strength when using a heat-sensitive aqueous adhesive by using polyvinyl alcohol together.

  Polyvinyl alcohol has different properties depending on the degree of saponification, and it is preferable to select the degree of saponification 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 ink fixing layer is increased, and foaming does not occur during preparation of the coating liquid, and the workability during production is very high. It is good. Further, when partially saponified polyvinyl alcohol having a saponification degree of 75 to 90% is used, the flexibility of the ink fixing layer is excellent and it is very effective in preventing the cracking. These polyvinyl alcohols having different saponification degrees may be used alone or in combination depending on the purpose.

The polymerization degree of polyvinyl alcohol is preferably 1000 or more, and particularly preferably 1500 to 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, which is not preferable. The polyvinyl alcohol may be modified polyvinyl alcohol such as cationic polyvinyl alcohol or silyl-modified polyvinyl alcohol.
Depending on the heat-sensitive aqueous adhesive used, the blending ratio of the heat-sensitive water-based adhesive and polyvinyl alcohol is 15 to 65 parts by weight of polyvinyl alcohol with respect to 100 parts by weight (solid content) of the heat-sensitive water-based adhesive (solid content). Solid content), preferably 25-50 parts by weight.

  In addition to polyvinyl alcohol and heat-sensitive water-based adhesive, other known water-dispersible binders and water-soluble binders can be used alone or in combination for the ink fixing layer.

  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. The heat-sensitive aqueous adhesive of the present invention is preferably 10 to 48 parts by mass, more preferably 20 to 40 parts by mass with respect to 100 parts by mass of the pigment. If the blending amount is less than 10 parts by mass, thermal deformation may not be sufficient, and if it exceeds 50 parts by mass, the ink absorbability may be impaired. In addition, the compounding quantity here is a compounding quantity with respect to 100 mass parts of silica-cationic compound aggregate particles, when using silica-cationic compound aggregate particles as a pigment. Since the ink fixing layer contains a lot of pigment, even if a heat-sensitive aqueous adhesive is present, it does not exhibit heat sealability by heating.

(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) represented by dicyandiamide-polyethyleneamine copolymers Polyamine cationic compounds, (he) epichlorohydrin-dimethylamine copolymer, (to) diallyldimethylammonium-SO ₂ polycondensate, (thi) diallylamine salt-SO ₂ polycondensate, (li) diallyldimethylammonium Chloride polymerization , (Nu) allylamine salt copolymer, (le) dialkylaminoethyl (meth) acrylate quaternary salt copolymer, (e) acrylamide-diallylamine copolymer, (wa) cationic having a 5-membered ring amidine structure Examples thereof include resins.

  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 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 gas phase method silica used for forming the silica-cationic compound aggregate particles is a primary particle having an average particle diameter of 3 to 40 nm. The aggregate particles are substantially composed of primary particles. It consists of secondary particles formed by agglomeration. The silica-cationic compound aggregate particles preferably have an average particle size of 0.01 to 1 μm, and the average particle size is appropriately adjusted by pulverization and dispersion. 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 aggregate 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. Further, when the outermost layer is formed, since the penetration of the outermost layer coating liquid can be prevented, the gloss is improved. However, since excessive use tends to impair ink absorbability, about 5 to 30 parts by weight, preferably about 10 to 20 parts by weight, is added to 100 parts of silica-cationic compound aggregate particles in 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.

  In addition, a single cationic compound may be blended in the ink fixing layer in order to further improve the ink fixing property and improve the water resistance. As a cationic compound, the cationic compound used by the said silica-cationic compound aggregate can be illustrated, Among these, the water-soluble resin or the thing of an emulsion is used preferably. 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 No. 2002-160439), a water-soluble binder, which exhibits high 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 these, 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 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. 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.

(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 an adhesive agent, If it uses excessively, since the absorptivity of an ink solvent will be impaired, 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.

In the undercoat layer, 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. 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. .
The undercoat layer may be subjected to a smoothing process such as super calendering or brushing as necessary.

[Outermost layer]
In the present invention, the ink fixing layer can be calendered to obtain an ink jet recording material. However, in order to obtain a higher gloss surface, it is preferable to provide an outermost layer on the ink fixing layer and calender it. . In addition, after calendaring the ink fixing layer, an outermost layer may be provided and calendared. The outermost layer is composed mainly of colloidal particles or a resin and has a dry coating amount of about 0.1 to 5 g / m ^2, so that the productivity is excellent and a clearer image can be obtained. Since the coating amount of the outermost layer is so small, it is not always necessary to add an ink fixing agent to the outermost layer.

(Colloidal particles)
When colloidal particles are used for the outermost layer, the colloidal particles 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 Glossiness 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)
Some colloidal silicas have self-adhesive properties and do not necessarily require a binder, but the outermost layer using fine pigment is intended to fix colloidal particles on the ink fixing layer And contains a binder. 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 outermost layer, substances contained in the ink fixing layer may be extracted and dissolved during operation. When the ink fixing layer contains substances such as boric acid and borax, or when these substances provided under the ink fixing layer are mixed, these may be mixed in the outermost layer. In this sense, the binder contained in the outermost layer is preferable because acrylic resins and urethane resins are less likely to react with boron compounds than polyvinyl alcohol and the like. However, water-soluble adhesives such as polyvinyl alcohol, gelatin, and casein generally have a harder dry film than acrylic resins and urethane resins, so they are less likely to be scratched when fed into a printer and meet the required quality. It is important to master these.
When the colloidal particles in the outermost layer are cationic, or when an ink fixing agent is blended in the outermost layer, it is necessary to use polyvinyl alcohol, gelatin, or a cation-modified binder. When the colloidal particles in the outermost layer are anionic, polyvinyl alcohol, casein, or an anionic binder can be used.

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

(resin)
In the case of using a resin for the outermost layer, the resins exemplified as the binder can be used, but among them, the use of acrylic resin or urethane resin is preferable. The use of an acrylic resin or a urethane resin can further improve the glossiness by calendar treatment.
In order not to inhibit the ink absorptivity, it is desirable to use a resin having a molecular weight of about 3000 and weak film forming property at a temperature of 150 ° C. or lower.

(Other additives)
In addition, an ink fixing agent, a dispersant, a cross-linking agent, a thickener (fluid modifier), an antifoaming agent, a water-proofing agent (printability improver), an antistatic agent, an antiseptic agent are provided on the outermost layer as necessary. Various additives such as an agent, an ultraviolet absorber, a storage stability improver, a fluorescent brightening agent, and a coloring agent can be appropriately added. In particular, the combined use of a thickener is preferable because it prevents the outermost layer from penetrating and allows the outermost layer resin to be unevenly distributed on the surface.
When coating the outermost layer coating solution, various known coating methods can be employed. For example, a coating device such as a blade, brush coater, chamber coater, bar coater, or gravure coater is appropriately used. It is good to use.

<Calendar processing>
In the present invention, after the ink fixing layer is formed or after the outermost layer is formed, the surface of the coating layer needs to be smoothed by a calendar. When the surface temperature of the calendar is low, the heat-sensitive water-based adhesive is not sufficiently softened, smoothing is insufficient, and gloss tends not to be obtained. When the surface temperature of the calendar is high, smoothing is sufficiently performed and gloss is obtained, but the film formation of the heat-sensitive aqueous adhesive proceeds, the surface porosity is lowered, and the ink absorption rate may be lowered. Therefore, the surface temperature of the calendar is preferably about 20 ° C to 200 ° C, more preferably 20 ° C to 150 ° C.

  Here, examples of the calendar include known calendar devices such as a super calendar, a calendar, and a thermal calendar. For example, the surface of the coating layer hits a heated roll such as a metal having a mirror surface (smooth surface). This is a device for passing paper between other rolls and applying pressure. 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 (share D). The linear pressure between the nip of the mirror surface roll and the elastic (rubber) roll is 10 kg / cm to 200 kg / cm, preferably 10 kg / cm to 150 kg / cm. 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. Adjust the 75 ° glossiness of the coated surface to 45% or more and 85% or less.

The reason why an ink jet recording material particularly excellent in gloss and ink jet recording suitability can be obtained by the present invention is considered as follows.
Since the heat-sensitive water-based adhesive blended in the ink fixing layer has a property of being easily deformed by heat, it is pressed in a softened state by the heat during the calendering process, so that almost no voids in the ink fixing layer are crushed. Smoothed. At this time, since the film is formed in a range where the resin component on the very surface does not impair the ink absorbability, the surface strength is excellent. For this reason, when a heat calendar process is performed, both glossiness and ink absorbability can be obtained efficiently. Further, when a fine secondary particle pigment having an average particle diameter of 10 nm to 1 μm is used as the pigment, the glossiness can be improved because a uniform ink fixing layer containing no coarse particles is obtained. In particular, when vapor-phase process silica is used as the pigment, the secondary particle diameter is sufficiently small, so that the smoothness of the surface obtained by calendering is excellent and the printing density is improved. By using the vapor phase silica, the transparency of the ink fixing layer is increased, so that the color of the ink held in the ink fixing layer when recording is not hindered by the ink fixing layer having increased transparency, As a result, the print density is expected to improve.
It is possible to modify the surface of the ink fixing layer within a range that does not impair the effects of the present invention, such as providing a trace amount of the outermost layer in a range that does not adversely affect the gloss, absorbency, etc. Within range.

  On the back surface of the support (the surface on which no ink fixing layer is formed), a coat layer or a laminate layer is provided to correct curling to the front surface side, and a polyolefin resin laminate layer is provided to give a silver salt photograph texture. It is preferable to provide a back layer, such as providing. 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 the ink fixing layer is formed, it is preferable to treat the back surface before forming the ink fixing layer because the ink fixing 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.

"Creation of silica-cationic compound aggregate particles"
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 silica-cationic compound aggregate particle dispersion having an average secondary particle size of 0.15 μm was prepared.

"Preparation of coating solution for ink fixing layer"
As a fine pigment, 100 parts by mass (solid content) of the above silica-cationic compound aggregate 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) and 35 parts by mass of a polyolefin-vinyl acetate copolymer (manufactured by Chuo Rika Kogyo Co., Ltd., trade name: Aquatex EC1200 MFT = 60 ° C., particle size 1.4 μm) as a heat-sensitive aqueous adhesive, polyethylene wax (Meisei Chemical Co., Ltd., trade name: Meikatex PEC270, melting point 90 ° C.) 10 parts by mass, dispersant (manufactured by Toa Gosei Co., Ltd., trade name: Aron SD-10) 0.05 parts by mass are mixed in water to be dispersed in water. A liquid (concentration: 20% by mass) was prepared.

"Preparation of outermost coating solution"
60 parts by mass of water-based urethane resin (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Elastron BN-27) in water, 30 parts by mass of casein, 11 parts by mass of xanthan gum (manufactured by Rhodia Nikka Co., Ltd., trade name: Road Pole 23), 5 parts by mass of polyvinyl pyrrolidone (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Pitzkor K90) and 0.1 part by mass of an antifoaming agent (Shin-Etsu Chemical Co., Ltd., trade name: X-50-1003) are charged and mixed. An aqueous dispersion (concentration 3% by mass) was prepared.

"Formation of ink fixing layer"
Apply the coating solution for the ink fixing layer having the above composition on the coating layer surface of the paper support using a Mayer bar and dry it with a dryer. 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 fixing layer was 5 g / m ² , and the dry coating amount of the outermost 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
Instead of the polyolefin-vinyl acetate copolymer (manufactured by Chuo Rika Kogyo Co., Ltd., trade name: Aquatex EC1200) used as a heat-sensitive aqueous adhesive in the preparation of a coating solution for an ink fixing layer, a heat-sensitive water-based adhesive was used. An inkjet recording material was obtained in the same manner as in Example 1 except that a polyolefin-vinyl acetate copolymer (manufactured by Chuo Rika Kogyo Co., Ltd., trade name: Aquatex EC1700 MFT = 60 ° C., particle diameter 1.7 μm) was used. .

Example 3
Instead of the polyolefin-vinyl acetate copolymer (manufactured by Chuo Rika Kogyo Co., Ltd., trade name: Aquatex EC1200) used as a heat-sensitive aqueous adhesive in the preparation of a coating solution for an ink fixing layer, a heat-sensitive water-based adhesive was used. An inkjet recording material was obtained in the same manner as in Example 1 except that a polyolefin-vinyl acetate copolymer (manufactured by Chuo Rika Kogyo Co., Ltd., trade name: Aquatex EC3200 MFT = 70 ° C., particle diameter 3.2 μm) was used. .

Example 4
In the preparation of the coating solution for the ink fixing layer, the same procedure as in Example 1 was performed except that the number of parts of polyethylene wax (manufactured by Meisei Chemical Co., Ltd., trade name: Meikatex (PEC270)) was changed from 10 parts by mass to 20 parts by mass. An ink jet recording material was obtained.

Example 5
In the preparation of the coating solution for the ink fixing layer, the number of parts of the polyolefin-vinyl acetate copolymer (manufactured by Chuo Rika Kogyo Co., Ltd., trade name: Aquatex EC1200) used as a heat-sensitive aqueous adhesive is 35 to 30 parts by mass. Furthermore, 10 parts by mass of ethylene-vinyl acetate copolymer (manufactured by Sumika Chemtex Co., Ltd., trade name: Sumikaflex 455HQS MFT = 0 ° C., particle size 0.8 μm) as a heat-sensitive aqueous adhesive is added, The number of parts of polyethylene wax (manufactured by Meisei Chemical Co., Ltd., trade name: Meikatex (PEC270)) was changed from 10 parts by mass to 12.5 parts by mass, and 15 parts by mass of polyvinyl alcohol having a polymerization degree of 1700 and a saponification degree of 98.0%. Instead, in the same manner as in Example 1, except that 13 parts by mass of polyvinyl alcohol having a polymerization degree of 2400 and a saponification degree of 98.0% was used. It was obtained Kujetto recording material.

Example 6
In the preparation of the coating solution for the ink fixing layer, the number of parts of the polyolefin-vinyl acetate copolymer (manufactured by Chuo Rika Kogyo Co., Ltd., trade name: Aquatex EC1200) used as the heat-sensitive aqueous adhesive is from 30 parts by mass to 25 parts by mass. Except that the number of parts of the ethylene-vinyl acetate copolymer (manufactured by Sumika Chemtex Co., Ltd., trade name: Sumikaflex 455HQS) used as a heat-sensitive aqueous adhesive was changed from 10 parts by weight to 20 parts by weight. In the same manner as in Example 5, an ink jet recording material was obtained.

Example 7
In the preparation of the coating solution for the ink fixing layer, the number of parts of the polyolefin-vinyl acetate copolymer (manufactured by Chuo Rika Kogyo Co., Ltd., trade name: Aquatex EC1200) used as the heat-sensitive aqueous adhesive is 35 to 20 parts by mass. An ink jet recording material was obtained in the same manner as in Example 1 except that the above was changed.

Example 8
In the preparation of the coating solution for the ink fixing layer, the number of parts of the polyolefin-vinyl acetate copolymer (manufactured by Chuo Rika Kogyo Co., Ltd., trade name: Aquatex EC1200) used as a heat-sensitive aqueous adhesive is 35 to 40 parts by mass. An ink jet recording material was obtained in the same manner as in Example 1 except that the above was changed.

Example 9
In preparation of the coating solution for the ink fixing layer, the number of parts of the polyolefin-vinyl acetate copolymer (manufactured by Chuo Rika Kogyo Co., Ltd., trade name: Aquatex EC1200) used as a heat-sensitive aqueous adhesive is 35 to 10 parts by mass. An ink jet recording material was obtained in the same manner as in Example 1 except that the above was changed.

Example 10
In the preparation of the coating solution for the ink fixing layer, the number of parts of the polyolefin-vinyl acetate copolymer (manufactured by Chuo Rika Kogyo Co., Ltd., trade name: Aquatex EC1200) used as a heat-sensitive aqueous adhesive is 35 to 50 parts by mass. An ink jet recording material was obtained in the same manner as in Example 1 except that the above was changed.

Example 11
An ink jet recording material was obtained in the same manner as in Example 1 except that the surface temperature of the metal roll was set to 70 ° C. as the calendar condition.

Example 12
In the preparation of the coating solution for the outermost layer, the number of water-based urethane resin (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Elastron BN-27) was changed from 60 parts by weight to 80 parts by weight, and xanthan gum (Rhodia Nikka Co., Ltd.). Manufactured, trade name: load pole 23) from 11 parts by weight to 7 parts by weight, casein 30 parts by weight, polyvinyl pyrrolidone (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Pitzkor K90) 5 parts by weight Instead, an inkjet recording material was obtained in the same manner as in Example 1 except that 20 parts by mass of colloidal silica (produced by Grace Japan, trade name: Ludox AS-40 25 nm) was used.

Comparative Example 1
In the preparation of the coating solution for the ink fixing layer, the polyolefin-vinyl acetate copolymer (manufactured by Chuo Rika Kogyo Co., Ltd., trade name: Aquatex EC1200) used as a heat-sensitive water-based adhesive is not blended, but acrylic as a binder instead. An ink jet recording material was obtained in the same manner as in Example 1 except that a resin (manufactured by Nissin Chemical Industry Co., Ltd., trade name: Vinibrand C-EM-4 Tg = 20 ° C., particle size 0.05 μm) was used.

Comparative Example 2
In the preparation of the coating solution for the ink fixing layer, the polyolefin-vinyl acetate copolymer (manufactured by Chuo Rika Kogyo Co., Ltd., trade name: Aquatex EC1200) used as a heat-sensitive water-based adhesive is not blended, but acrylic as a binder instead. An ink jet recording material was obtained in the same manner as in Example 1 except that a resin (manufactured by Chuo Rika Kogyo Co., Ltd., trade name: Rikabond FK820 Tg = −46 ° C., particle size 0.3 μm) was used.

Evaluation Method “Measurement of 60 ° Gloss”
According to JIS-Z8742, the glossiness of the surface of the ink jet recording material on the ink fixing layer side was measured under conditions where the incident angle and the light receiving angle were 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.

  The ink absorbability and image color density of the obtained ink jet recording material were evaluated by the following methods. 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.

  As can be seen from Table 1, the ink jet recording material of this example was an ink jet recording material having both ink jet recording suitability and gloss.

  The present invention makes it possible to achieve both gloss and recordability that could not be achieved by the 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 (7)

An inkjet recording body having an ink fixing layer containing at least a pigment, a binder, and an ink fixing agent on a support, wherein the inkjet recording body contains polyvinyl alcohol and a heat-sensitive aqueous adhesive as a binder for the ink fixing layer. Is an ink jet recording material that is processed by a calendar. The ink jet recording body according to claim 1, wherein the ink fixing layer contains 10 to 48 parts by mass of a heat-sensitive aqueous adhesive with respect to 100 parts by mass of the pigment. The ink jet recording material according to claim 1, wherein the ink fixing layer contains gas phase method silica as a pigment. The ink jet recording material according to any one of claims 1 to 3, wherein the heat-sensitive aqueous adhesive is an adhesive mainly comprising a polyolefin-vinyl acetate copolymer. The inkjet recording body according to any one of claims 1 to 4, wherein the ink fixing layer contains polyethylene wax. A method for producing an ink jet recording material, comprising: providing an ink fixing layer containing at least one layer of a pigment, a heat-sensitive aqueous adhesive as a binder, and an ink fixing agent on a support; The method for producing an ink jet recording material according to claim 6, wherein after the ink fixing layer is provided, an outermost layer is provided, and then a calendar process is performed.