JP2006002259A - Method for producing cast-coated sheet and cast-coated sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably provide a cast-coated sheet having excellent glossiness and excellent ink-jet printing suitability and suitable for ink-jet recording. <P>SOLUTION: A first method for producing the cast-coated sheet comprises forming a coating layer with 12-40 mass% moisture content on an air-permeable support, applying a wetting liquid to the surface of the layer, then bringing the resultant layer into pressure contact with a heated mirror surface, drying the layer and thereby forming a gloss layer. A second method for producing the cast-coated sheet comprises coating the top surface of the air-permeable support with a coating liquid for the gloss layer, forming the coating layer, then thickening or making the layer gel, further applying the wetting liquid to the surface thereof in a state of the layer with ≥12 mass% moisture content, bringing the layer into pressure contact with the heated mirror surface, drying the layer and thereby forming the gloss layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a cast coated sheet and a cast coated sheet.

  The cast coating method is one of the methods for forming a glossy layer on a gas-permeable support (base paper, etc.). In general, a cast drum (heating drum) whose surface is mirror-finished is used, and a wet state (re-wet state) is achieved. The mirror surface is copied to the coating layer in the

Conventionally, cast coating methods include:
(1) A wet casting method in which a coating layer is formed by coating a gloss layer coating solution on a support, and the layer is pressed against a cast drum in a wet state;
(2) A gelled casting method in which a coating layer is formed by applying a coating solution for a gloss layer on a support, the layer is gelled, and then pressed against a cast drum;
(3) A gloss layer coating solution is applied onto the support to form a coating layer, the layer is sufficiently dried, re-wet with water or a wetting solution, and then pressed against a cast drum. Rewet cast method to finish
(4) A dry casting method in which the same steps as in the rewet casting method (3) are performed, but the coated layer is sufficiently dried and then pressed against the cast drum without being rewet.
(5) There is a precast method in which a coating layer is formed by applying a gloss layer coating solution on the cast drum side, the layer is dried, and then pressed and transferred to a support (non-patent document). 1).

  On the other hand, an ink jet recording sheet is required to have high ink absorptivity in order to cope with high-speed printing and multicolor printing. Therefore, conventionally, high-quality paper devised so as to have high ink absorbability, coated paper with a porous pigment coated on the surface, and the like have been mainstream. However, any of these conventional inkjet recording sheets has a low surface gloss and a matte tone, and the printed appearance is not good. Therefore, application of a cast coating method has been proposed in order to enable more beautiful printing.

  As cast coating sheets for inkjet recording, for example, (1) wet cast method (Patent Document 1), (2) gelled cast method (Patent Document 2), (3) rewet cast method (Patent Document 3) There has been proposed a coating provided with a gloss layer. In Patent Document 2, a gloss layer coating liquid containing a pigment and an adhesive is applied onto a support, and a coagulant (gelling agent) capable of coagulating the adhesive is further applied to form a gel. I am letting.

As a technique for imparting glossiness to a recording sheet, in addition to the cast coating method, there is a technique for smoothing the surface of a coating layer by passing between rolls to which pressure or temperature is applied using a calendar device.
JP 7-89220 A JP 2002-166644 A Japanese Patent Publication No. 7-96331 Paper Pulp Technology Association, “Paper Pulp Production Technology Series 8 Coating”, published by Paper Pulp Technology Association, August 17, 1993, p. 269-282

  In the cast coating method, it is necessary to use a gas-permeable support as the support in order to escape the vapor that escapes from the coating layer when pressed against the cast drum. For this reason, compared to photo glossy paper or the like using a non-permeable support such as photographic paper, the smoothness of the support surface is poor, and the gloss layer formed thereon is affected by the influence. Therefore, there is a limit to the gloss that can be obtained by the conventional cast coating technique, and a higher level of gloss is required.

  Furthermore, in the cast coated sheet for ink jet recording, it is important that the ink jet printing suitability is good in addition to the improvement in glossiness. However, in the prior art, it is difficult to achieve both.

  That is, (1) the one using the wet cast method (Patent Document 1) has sufficient ink absorbability, but the influence of the surface shape of the support on the gloss layer surface is large, and the gloss layer has excellent surface smoothness. Difficult to get. As a result, printability such as gloss and roundness of ink dots tends to be inferior.

  (2) In the thing (patent document 2) to which the gelation cast method is applied, the solid content concentration of the coating liquid to be applied first is set to 5% by mass or less for the gelation reaction. Therefore, the moisture content of the coating layer is large and the drying efficiency is poor, and the coating layer is cracked during drying, and the glossiness associated with this tends to be reduced. In addition, it is difficult to control gelation, and it is difficult to form a uniform gloss layer, which tends to cause a decrease in gloss and uneven printing during solid printing. Therefore, it is difficult to stably obtain a cast coated sheet for inkjet recording having good gloss and printability.

  (3) In the case of applying the rewet casting method (Patent Document 3), since the coating layer is once dried, after re-wetting as compared with other casting methods (wet casting method, gelation casting method, etc.) The degree of plasticization of the coating layer is extremely low, the plasticization tends to be uneven, and it is difficult to form a uniform glossy layer. Therefore, it is difficult to stably obtain a cast coating sheet for ink jet recording having good glossiness and printability.

  Also, with the smoothing technology that uses a calender device and pressurizes under heating, the voids in the coating layer decrease as the applied pressure increases, and the ink absorptivity (ink absorption speed and absorption capacity) decreases. End up. Therefore, it is difficult to achieve both good ink absorbability and glossiness.

  The present invention has been made in view of the above circumstances, and an object thereof is to stably provide a cast coating sheet having improved gloss. Another object of the present invention is to stably provide a cast coating sheet that is excellent in both glossiness and inkjet printing suitability and suitable for inkjet recording.

  The inventor diligently studied to solve the above-mentioned problems, and invented the following cast coating sheet manufacturing method and cast coating sheet.

The manufacturing method of the 1st cast coating sheet | seat of this invention forms a coating layer with a moisture content of 12-40 mass% on a gas-permeable support body, and after applying a wetting liquid to the surface of this layer, it heats. A glossy layer is formed by press-contacting to a mirror surface and drying.
In the second cast coating sheet production method of the present invention, a gloss layer coating liquid is applied on a gas-permeable support to form a coating layer, and then the layer is thickened or gelled. Further, when the moisture content of the layer is 12% by mass or more, a wetting liquid is applied to the surface, and this layer is pressed against a heated mirror surface and dried to form a glossy layer.
In the present specification, “thickening” means that the viscosity increases without crosslinking, and “gelation” means that the viscosity increases greatly due to crosslinking.

In any of these production methods, a coating layer is formed on a gas-permeable support, rewetted while the layer is in a wet state, and pressed against a heated mirror surface to form a glossy layer. ,
Conventional cast coating method, that is, (1) wet cast method that does not rewet, (2) gelled cast method that does not rewet after gelation, and (3) the coating layer is sufficiently dried (dried) (The water content after that is much less than 12% by mass), rewetting cast method for rewetting, (4) dry casting method for drying the coating layer without rewetting, and (5) forming the coating layer on the cast drum side It is a completely new method that is different from any of the precast methods.

In this specification, the “moisture content of the coating layer” is measured using an infrared moisture meter KJT-100 (manufactured by Kett Science Laboratory). If a paper roll or the like is in contact with the opposite side of the measurement surface, an error may occur in the measured value due to the influence. Therefore, measurement is performed at a location where no other member is in contact with the opposite side of the measurement surface. Shall.
An infrared moisture meter irradiates the coating layer with light having an absorption wavelength of water in the near infrared region (specifically, 1.2 μm, 1.45 μm, 1.94 μm). Since it is absorbed, this is used to measure the amount of water from the amount of attenuation. Strictly speaking, since measurement with only the absorption wavelength is affected by the surface condition and color of the layer, and stable measurement is difficult, a near infrared ray (reference wavelength) that is not easily affected by water is set separately. The amount of moisture is calculated from the ratio of the energy of the two wavelengths of light that are alternately irradiated with light of the reference wavelength and reflected.

In the second cast coated sheet production method of the present invention, hydrophilicity is exhibited in a specific temperature range, hydrophobicity is exhibited in a different temperature range, and the liquid containing this is thickened or gels in a temperature range exhibiting hydrophilicity. Coating the glossy layer coating solution in a temperature range where the temperature sensitive polymer compound exhibits hydrophobicity. After forming the layer, it is preferable to thicken or gel the layer by changing the temperature to a temperature range in which the thermosensitive polymer compound exhibits hydrophilicity.
Moreover, as said thermosensitive polymer compound, what exhibits hydrophilicity below a temperature sensitive point, hydrophobicity above a temperature sensitive point, and a temperature sensitive point is 0-30 degreeC is suitable.
A recording medium using such a thermosensitive polymer compound is disclosed in Japanese Patent Application Laid-Open No. 2003-40916 and the like, and is well known, but the document does not mention application to the glossy layer. .

  In the present specification, the term “hydrophilic” means that in a system in which a temperature-sensitive polymer compound and water coexist, the temperature-sensitive polymer compound is more compatible with water than the phase-separated state. “Hydrophobic” means that the temperature-sensitive polymer compound is more stable in a phase-separated state than water than in a compatible state in a similar system. .

  The manufacturing method of the 1st, 2nd cast coating sheet of this invention is preferably applicable to the cast coating sheet for inkjet recording.

  The cast coated sheet of the present invention is produced by the method for producing the first or second cast coated sheet of the present invention.

  According to the technique of the present invention, it is possible to stably provide a cast coating sheet having high gloss that cannot be achieved by a conventional cast coating method. This cast coated sheet is also suitable for inkjet printing (print density, suppression of printing blur, uniformity of solid printing, etc.), and according to the present invention, it is excellent in both glossiness and inkjet printing suitability, and for inkjet recording. A suitable cast coating sheet can be provided stably.

Hereinafter, the present invention will be described in detail.
"Production method of cast coating sheet"
The cast coating sheet has a gloss layer on a gas-permeable support. In the present invention, the gloss layer forming step is characteristic. An undercoat layer can be provided between the air-permeable support and the gloss layer as necessary.
Hereinafter, the air-permeable support, the undercoat layer, and the gloss layer will be described in this order. Since the present invention can be preferably applied to a cast coating sheet for ink jet recording, the composition of the layer and the like will be described on the basis of ink jet recording, but the present invention is of course applicable to other uses.

"Air-permeable support"
The air-permeable support is not particularly limited as long as it has air-permeability, and includes air-permeable base paper such as acid paper and neutral paper used for general coated paper, and air-permeable resin sheet. Can be mentioned.
Considering the operability (ease of vapor removal) when casting the glossy layer (when the coating layer is pressed against the heated mirror surface) and the suppression of penetration of the coating liquid into the support, The air permeability is preferably 10 to 350 seconds / cc, more preferably 10 to 200 seconds / 100 cc, and particularly preferably 20 to 100 seconds / 100 cc.

When air permeable base paper is used, the degree of beating (freeness) of the pulp used is about 250 to 550 ml (CSF: JIS-P-8121), especially 300 to 500 ml, considering the effects of surface smoothness and moisture during casting. The degree is preferred.
Further, when a paper strength enhancer is added to the air-permeable base paper, the dimensional stability and strength of the base paper when casted in a wet state can be improved. Examples of the paper strength enhancer include polyamide / epichlorohydrin resin, N-vinylformamide / vinylamine copolymer, and the like. Among these, polyamide epichlorohydrin resin is preferable because it has a large effect of improving the dimensional stability of paper when wet. The paper strength enhancer can be used by internally adding, coating, or impregnating the gas-permeable base paper.

"Undercoat"
On the air-permeable support, a single layer or a plurality of undercoat layers can be provided as necessary. Glossiness can be improved by forming the gloss layer through the undercoat layer. This is presumed to be due to the improved adhesion of the coating layer to the heating mirror surface at the time of cast finishing due to the presence of an undercoat layer that is more flexible than the support.
In addition, for ink-jet recording and the like, providing the undercoat layer increases the overall ink absorbability, and therefore tends to improve printability such as printing density, suppression of printing blur, and uniformity of solid printing, which is preferable.

  The composition of the undercoat layer is not particularly limited, but for ink jet recording and the like, it preferably contains a pigment responsible for ink absorption and an adhesive for fixing the pigment to a support.

There is no restriction | limiting in particular as a pigment used for an undercoat layer, The thing similar to a glossy layer is used (refer paragraph [0046]). In particular, amorphous silica, alumina, zeolite, and the like are preferably used as the main component pigment of the undercoat layer because they are excellent in ink absorbability. In addition, zinc oxide, titanium oxide, plastic pigments, and the like are suitable for use because they have a function of preventing yellowing of the non-printed portion.
The average particle diameter of the pigment (aggregated particle diameter in the case of an agglomerated pigment) is not particularly limited, but is about 1 to 12 μm from the viewpoint of ink absorptivity, surface smoothness and glossiness of a gloss layer to be formed later, Is preferably 2 to 10 μm, particularly preferably 2 to 7 μm, and a plurality of pigments having different average particle diameters within this range can be used in combination.

  In addition, for the purpose of adjusting ink absorbency and suppressing penetration of the gloss layer coating liquid into the undercoat layer, a pigment having a small average particle diameter, for example, an average particle diameter of less than 1 μm can be used in combination. . Examples of such pigments include colloidal silica and alumina sol. Colloidal silica is particularly preferably used.

The colloidal silica (S) that is blended as a subcomponent as necessary is preferably blended in combination with a polymer (P) obtained by polymerizing a monomer having an ethylenically unsaturated bond. That is, the undercoat layer preferably contains colloidal silica (S) and a polymer (P) of a monomer having an ethylenically unsaturated bond, or contains a complex thereof.
With this configuration, the glossiness is further improved. The reason is not necessarily clear, but the presence of the colloidal silica (S) and the polymer (P), or a composite thereof, can be applied to the undercoat layer of the gloss layer coating liquid while maintaining the ink absorbency of the undercoat layer. It is estimated to suppress the penetration of Furthermore, although a reason is unknown, there exists a tendency which the mold release property from the heating mirror surface at the time of cast finishing of a glossy layer also improves.

Colloidal silica (S) is classified into an alkaline type and an acidic type, and is appropriately selected according to physical properties such as pH of the undercoat layer coating solution. As the colloidal silica (S), either spherical or non-spherical can be used. Spherical colloidal silica is superior in terms of glossiness, and nonspherical colloidal silica is superior in terms of ink absorptivity. And use.
The average particle diameter of the colloidal silica (S) is not particularly limited, but is preferably 4 to 200 nm, particularly preferably 10 to 60 nm.
Although the compounding quantity of colloidal silica (S) does not have a restriction | limiting in particular, 1-30 mass parts with respect to 100 mass parts of other pigments, 1-10 mass parts is especially preferable.

The ethylenic monomer of the polymer (P) is not particularly limited, but various (meth) acrylic acid esters, styrene, α-methylstyrene, vinyltoluene, acrylonitrile, vinyl chloride, vinylidene chloride, vinyl acetate, vinyl propionate , Acrylamide, N-methylolacrylamide, ethylene, butadiene and the like.
The polymer (P) may be a homopolymer or a copolymer, and may further be a substituted derivative of these polymers. Examples of the substituted derivative include those introduced with a carboxy group and those obtained by modifying the introduced carboxy group to be alkali-reactive.
Although the compounding quantity of a polymer (P) does not have a restriction | limiting in particular, 1-20 mass parts with respect to 100 mass parts of pigments other than colloidal silica (S), Especially 1-5 mass parts is preferable.

The composite of colloidal silica (S) and polymer (P) is, for example,
(1) The above-mentioned ethylenic monomer, which is a raw material for the polymer (P), is polymerized in the presence of a silane coupling agent or the like and colloidal silica (S) to form a Si—O—P bond (P: polymer component). And is compounded simultaneously with the production of the polymer (P).
(2) A polymer (P) modified with a silanol group or the like and a colloidal silica (S) are reacted as necessary to produce a Si—O—P bond (P: polymer component) and to make a composite. Etc. are obtained.

  There is no restriction | limiting in particular as an adhesive agent used for an undercoat layer, The thing similar to a glossy layer is used (refer paragraph [0049]). The blending ratio of the pigment and the adhesive is set according to these combinations, and is not particularly limited. However, the adhesive is preferably 1 to 100 parts by weight, particularly 2 to 50 parts by weight with respect to 100 parts by weight of the pigment. .

 In the undercoat layer, ink fixing agents such as various cationic compounds can be blended as required. However, it is preferable that the ink fixing agent is blended only in the glossy layer and the component is not substantially present in the undercoat layer because the printing density tends to increase. However, a small amount of a cationic surfactant or the like may be added as an auxiliary agent.

  In addition, an additive used in the production of general coated paper can be added to the undercoat layer as necessary, as in the case of the glossy layer (see paragraph [0056]).

The undercoat layer can be formed by preparing a coating solution containing the above-described components, coating this on a support, forming a coating layer, and drying. When a plurality of undercoat layers are provided, these steps are repeated.
The undercoat layer coating solution is usually adjusted to a solid content concentration of about 5 to 50% by mass.
The coating amount of the coating liquid is not particularly limited, but from the viewpoint of ink absorbability, glossiness, printing density, layer strength, etc., the absolute dry mass is about ² to 60 g / m ² , and further ² to 30 g / m. ^{About 2} , especially about 4-10 g / m ² is preferable. The coating method of the coating liquid is the same as that for the glossy layer.
After the coating layer is dried, it may be further subjected to a smoothing process such as super calendering or brushing as necessary.

  The undercoat layer can be blended with a thermosensitive polymer compound described later that is suitable for use in the gloss layer. In this case, after the temperature-sensitive polymer compound exhibits hydrophobicity, the temperature changes to a temperature range in which the temperature-sensitive polymer compound exhibits hydrophilicity after coating the coating liquid to form a coating layer. Thus, the undercoat layer can be formed by thickening or gelling the layer and then drying it. When the undercoat layer is formed by this method, the image quality at the time of inkjet printing tends to become clearer. This is presumed to be because the drying is performed in a state where the skeleton is formed in the layer, so that the resistance to the wind pressure of the hot air is increased, and the generation of fine bumps and the like is suppressed.

"Glossy layer"
In the present invention, the gloss layer forming method is characteristic.
In the first method for producing a cast coated sheet of the present invention, a coating layer having a water content of 12 to 40% by mass is formed on the air-permeable support or an undercoat layer provided on the support as necessary. A glossy layer is formed by applying a wetting liquid to the surface of the layer and then pressing it against a heated mirror surface and drying. In this production method, the coating layer may be thickened or gelled as necessary before applying the wetting liquid.

  The method for producing a second cast coating sheet of the present invention comprises applying a gloss layer coating liquid on a gas-permeable support or an undercoat layer provided on the gas-permeable support as necessary. After the layer is formed, the layer is thickened or gelled. Further, with the moisture content of the layer being 12% by mass or more, a wetting liquid is applied to the surface, and the layer is pressed against a heated mirror surface and dried. And forming a glossy layer.

In any of these production methods, a coating layer is formed on a gas-permeable support, and the layer is rewet while the layer is in a wet state, and this is pressed against a heated mirror surface. As a result, it was possible to stably provide a cast coating sheet having high gloss that cannot be achieved by the conventional cast coating method.
The reason for this is not clear, but is presumed as follows.
When a wetting liquid is applied to the surface while maintaining a certain amount of wet state with the skeleton of the gloss layer formed to some extent, the wetting liquid does not penetrate deeply into the inside of the layer. Acts only in the vicinity. As a result, it is presumed that non-uniform swelling during rewetting is suppressed, a thin and uniform rewetting layer is formed, and a high gloss cast surface is obtained.

Since the skeleton formation can be controlled well, the second production method is particularly preferable. Furthermore, among the second production methods, a method in which the coating layer is gelled and then rewet is preferred. The present inventor has found that cracking of the glossy layer is remarkably suppressed and high-quality printing can be obtained through gelation.
In addition, in the 2nd manufacturing method of this invention, unlike the 1st manufacturing method, the upper limit of the moisture content of the coating layer at the time of wet liquid application is not prescribed | regulated. This is because a skeleton is formed regardless of the amount of water. Therefore, in the second production method, the amount of water may be reduced or the same level may be maintained during thickening or gelation. Moreover, since a skeleton should just be formed, the degree of thickening or gelation may not be complete (so-called semi-thickening or semi-gelling).

  In any method, when the moisture content of the coating layer at the time of applying the wetting liquid is less than 12% by mass (when it does not gel, it corresponds to the conventional rewet casting method), a high gloss cast coating sheet can be stably formed. I can't get it. This is presumably because skeleton formation in the coating layer due to drying proceeds excessively, and the level of plasticization of the rewet layer becomes insufficient.

In addition, if the amount of moisture in the coating layer when applying the wetting liquid is extremely high, the amount of moisture evaporation when pressed against the heated mirror surface increases, resulting in defects such as pinholes on the surface of the coating layer. It tends to decrease. This is remarkable when it does not go through thickening or gelation. Therefore, in the 1st manufacturing method which does not require thickening or gelatinization, the upper limit of the moisture content of the coating layer at the time of moistening liquid application shall be 40 mass%. As a result, a good skeleton is formed in the coating layer before application of the wetting liquid, and excessive water evaporation at the time of press contact with the heating mirror surface is suppressed, so that a cast coating sheet having high gloss can be obtained. In the first production method, the moisture content of the coating layer at the time of applying the wetting liquid is preferably 14 to 35% by mass, particularly preferably 18 to 32% by mass.
In the second manufacturing method, since a high strength skeleton is formed by thickening or gelling, the formation of pinholes accompanying an increase in the amount of water evaporation when pressed against the heating mirror surface can be suppressed, but the same tendency is observed. It does not change. Therefore, also in the second production method, the moisture content of the coating layer when applying the wetting liquid is preferably 12 to 40% by mass, more preferably 14 to 35% by mass, and particularly preferably 18 to 32% by mass.

  The outline of the gloss layer formation in the production method of the present invention has been described above. Regardless of which method is employed, the basic components are common, so the common components will be described next. As a common component of the glossy layer, a pigment responsible for ink absorption, an adhesive for fixing the pigment to a support, and an ink fixing agent if necessary are used.

  The pigment used in the gloss layer is not particularly limited, but kaolin, clay, calcined clay, amorphous silica (amorphous silica), synthetic amorphous silica, zinc oxide, aluminum oxide, titanium oxide, aluminum hydroxide, carbonic acid Calcium, satin white, aluminum silicate, alumina, colloidal silica, zeolite, synthetic zeolite, sepiolite, smectite, synthetic smectite, magnesium silicate, magnesium carbonate, magnesium oxide, diatomaceous earth, styrene plastic pigment, hydrotalcite, urea resin plastic pigment And benzoguanamine-based plastic pigments. These can use 1 type (s) or 2 or more types.

The average particle diameter of the pigment is not particularly limited, but a fine pigment having an average particle diameter of 10 to 1000 nm is preferably used. By using pigments with such an average particle size, while maintaining good ink absorptivity, it suppresses the decrease in transparency of the glossy layer and the resulting decrease in color development during printing (ie, the decrease in print density). it can.
As the fine pigment, at least one selected from gas phase method silica, mesoporous silica, colloidal material of wet method silica produced by condensing activated silicic acid, alumina oxide, and alumina hydrate, particularly gas phase Method silica and / or alumina oxide is preferably used.

  In the present specification, the “average particle size” of the pigment is adjusted to 200 g of a 3% pigment aqueous dispersion regardless of the pigment form (powder or slurry) and stirred with a commercially available homomixer. After dispersion (dispersion conditions are 1000 rpm, 30 minutes), immediately observe with an electron microscope (SEM and / or TEM), take an electron micrograph of 10,000 to 400,000 times, and particles in a 5 cm square The martin diameter is measured and obtained by averaging (see “Fine Particle Handbook”, Asakura Shoten, p52, 1991).

Examples of the adhesive used in the gloss layer include casein, soybean protein, synthetic protein and other starches, various starches such as starch and oxidized starch, polyvinyl alcohol, cationic polyvinyl alcohol, modified polyvinyl alcohol such as silyl-modified polyvinyl alcohol, etc. Polyvinyl alcohols, cellulose derivatives such as carboxymethyl cellulose and methyl cellulose, styrene-butadiene copolymers, conjugated diene polymer latex of methyl methacrylate-butadiene copolymer, acrylic polymer latex, ethylene-vinyl acetate copolymer, etc. Examples include vinyl polymer latex, aqueous polyurethane resin, aqueous polyester resin, and the like. These can use 1 type (s) or 2 or more types.
The aqueous polyurethane resin is preferably used in the form of a polyurethane emulsion, polyurethane latex or the like.
In the second production method of the present invention, as described later, the thermosensitive polymer compound can be used in place of the general adhesive or in combination with the general adhesive.

  The blending ratio of the pigment and the adhesive is set according to these combinations, and is not particularly limited. However, the adhesive is preferably 1 to 100 parts by weight, particularly 2 to 50 parts by weight with respect to 100 parts by weight of the pigment. .

The ink fixing agent is a component that fixes a colorant (dye and / or colored pigment) component in the ink, and is used as necessary to improve the color development and storage properties of printing.
As the ink fixing agent, various cationic compounds are preferably used. Specific examples thereof include (1) polyalkylene polyamines such as polyethylene polyamine and polypropylene polyamine or derivatives thereof, and (2) secondary or tertiary. Acrylic polymers having amino groups and quaternary ammonium groups, copolymers with these acrylamides, (3) polyvinylamines and polyvinylamidines, and (4) dicyandications typified by dicyandiamide / formalin copolymers Compound, (5) polyamine cationic compound represented by dicyandiamide / polyethyleneamine copolymer, (6) epichlorohydrin / dimethylamine copolymer, (7) diallyldimethylammonium-SO ₂ polycondensate, (8) diallylamine salt · SO ₂ double condensate, ( ) Diallyldimethylammonium chloride polymer, (10) diallyldimethylammonium chloride-acrylamide copolymer, (11) copolymer of allylamine salt, (12) dialkylaminoethyl (meth) acrylate quaternary salt copolymer, (13 ) Acrylamide / diallylamine copolymer, (14) a cationic resin having a 5-membered ring amidine structure, and (15) a polymer of dimethylaminopropyl acrylamide. These can be used alone or in combination of two or more.

  Among them, diallyldimethylammonium chloride polymer, diallyldimethylammonium chloride-acrylamide copolymer, hydrochloride of acrylamide / diallylamine copolymer, dicyandiamide-polyethyleneamine copolymer, and a cationic resin having a 5-membered ring amidine structure. It is preferable to use at least one selected from the group because it is excellent in color developability, less blurring, and excellent printing without color unevenness.

  The blending amount of the ink fixing agent is not particularly limited, but is preferably 1 to 30 parts by weight, particularly 3 to 20 parts by weight with respect to 100 parts by weight of the pigment. When the amount of the ink fixing agent is less than 1 part by mass, the effect of the ink fixing agent such as an improvement in printing density is not sufficiently exhibited, and when it exceeds 30 parts by mass, the porosity is lowered due to the presence of the excessive ink fixing agent. As a result, the ink absorbability may be reduced.

In addition, since the silica used suitably as a pigment generally exhibits anionic property, it may produce a cationic ink fixing agent and an aggregate. This is particularly noticeable with fine silica. In this case, at least a part of the ink fixing agent is added to and dispersed in commercially available amorphous silica (having a relatively large secondary particle size of several μm), and then pulverized or refined. It is preferable to take a procedure such as adding an ink fixing agent to the silica secondary particle dispersion thus mixed, once aggregating, and then pulverizing again. Thereby, the formation of aggregates having a large particle size can be suppressed, and the pigment can be adjusted to a desired particle size.
The pigment treated in this manner has a characteristic that it is stabilized by exhibiting a structure in which the ink fixing agent is partially bonded, or is difficult to aggregate even if an ink fixing agent is added. Hereinafter, such a pigment is referred to as a cationic fine pigment.
Examples of the pigment used for the cationic fine pigment include silica, aluminosilicate, and the like. Silica, particularly gas phase method silica is preferable.

  The mass ratio of the pigment to the cationic compound in the cationic fine pigment is not particularly limited, but the cationic compound may be 1 to 30 parts by mass, particularly 3 to 20 parts by mass with respect to 100 parts by mass of the pigment. preferable. Moreover, it is preferable that the ratio of the cationic fine pigment in the total pigment constituting the glossy layer is 50% by mass or more because the transparency of the glossy layer is excellent.

  For the coating liquid for glossy layer, dispersants, thickeners, antifoaming agents, antistatic agents, preservatives, preservatives, fluorescent whitening agents, colorants used in the production of general coated paper Various additives such as can be added.

  In the second production method, a component for thickening or gelling is blended as necessary in addition to the common components. The same applies to the case of thickening or gelling in the first production method.

  The solid content concentration of the coating liquid for the gloss layer is not particularly limited, but is preferably 5 to 50% by mass, particularly preferably 5 to 20% by mass. By setting the solid content concentration to 5% by mass or more, the drying efficiency at the time of casting finish is improved, and by adjusting the solid content concentration to 50% by mass or less, moisture adjustment of the coating layer at the time of applying the wetting liquid becomes easy.

The coating amount of the gloss layer coating solution is not particularly limited, but is preferably ² to 15 g / m ² , more preferably ² to 10 g / m ² , and particularly preferably 3 to 8 g / m ² in terms of absolute dry mass.
By setting the coating amount to 2 g / m ² or more, excellent glossiness and ink absorbency can be obtained, and by setting the coating amount to 15 g / m ² or less, cracking of the gloss layer is suppressed, and dot trueness at the time of ink jet printing is suppressed. Good circularity and the like.

  Coating of the coating liquid is performed by various known coatings such as blade coaters, air knife coaters, roll coaters, brush coaters, champlex coaters, bar coaters, lip coaters, gravure coaters, curtain coaters, slot die coaters, slide coaters, spray devices, etc. It can be implemented using an apparatus. Among these, an air knife coater, a lip coater, a slide coater, a curtain coater, a slot die coater and the like are preferably used. If these coating devices are used, the glossiness tends to be better because it is less susceptible to the minute surface irregularities of the air-permeable support and the undercoat layer, and a coating layer with a uniform thickness can be formed. is there.

In the first production method, the gloss layer coating liquid is applied as described above to form a coating layer, and at least the moisture content of the layer when the wetting liquid is applied is 12 to 40% by mass.
This method is not particularly limited,
(I) Apply a gloss layer coating liquid having a water content of 12 to 40% by mass, and apply a wetting liquid while maintaining the water content at substantially the same level (if necessary, before applying the wetting liquid, And may be thickened or gelled.)
(Ii) A gloss layer coating liquid having a moisture content of more than 12% by mass is applied to form a coating layer, which is actively dried by a drying means such as a hot air dryer or an infrared heater, Is adjusted to 12 to 40% by mass,
(Iii) A coating layer is formed by applying a gloss layer coating solution having a moisture content of more than 12% by mass, and the coating layer has a moisture content of 12 to 40 by natural drying before applying the wetting solution. Adjust to mass%,
(Iv) A coating layer is formed by applying a coating liquid for a gloss layer having a water content of more than 12% by mass and a wetting liquid is applied. Utilizing the penetration of moisture into the provided undercoat layer, the moisture content of the coating layer is adjusted to 12-40% by mass,
And (v) combinations of (ii) to (iv).

  In the second production method, after the gloss layer coating liquid is applied to form a coating layer, the layer is thickened or gelled, and the moisture content of the layer is 12% by mass or more. Apply a wetting liquid to the surface. As a method for thickening or gelling the coating layer, there are a method using a coagulant (gelling agent) and a method not using this.

As a method of using a coagulant (gelator), a known method employed in a conventional gelling cast method, specifically, (1) a metal chelate compound such as aluminum or zinc in a coating solution for a gloss layer In addition, after coating, the formic acid and acetic acid are further applied as a gelling agent, and the chelate compound is decomposed to release metal ions, and the protein in the coating layer is gelled. Method, (2) Method of gelling the coating layer by applying a metal salt aqueous solution as a gelling agent after applying the coating solution for the glossy layer, and (3) Coating for the glossy layer After coating the liquid, a method in which a cross-linking agent is further applied as a gelling agent and the coating layer is gelled. (4) Before applying the gloss layer coating liquid, the base (air permeability support) is applied. (1) to (3) in advance on the body or an undercoat layer formed on the body as necessary) Leave impart gelling agents such as, methods and the like to gel simultaneously with the coating of the gloss layer coating liquid.
Among the methods (1) to (4), the method (4) is preferable in terms of control of gelation and layer uniformity after gelation.

  As a method not using a coagulant (gelling agent), (5) a method of thickening or gelling the coating layer by irradiating active energy rays such as an electron beam or heating, (6) temperature Examples include a method of using a thermosensitive polymer compound whose hydrophilicity / hydrophobicity is changed by the above, and using the property to thicken or gel.

Among the methods for thickening or gelling the coating layer, a method that does not use a coagulant (gelling agent) is preferable in terms of control of thickening or gelation and layer uniformity after thickening or gelling. In particular, the method (6) using a thermosensitive polymer compound that can be thickened or gelled only by changing the temperature is preferred. By adopting this method, a gloss layer excellent in uniformity, smoothness, glossiness, uniformity of solid printing and the like can be obtained.
Hereinafter, this method will be described in detail.

A thermosensitive polymer compound is hydrophilic in a specific temperature range, hydrophobic in a temperature range different from that, and in a temperature range exhibiting hydrophilicity, the liquid containing it becomes thickened or gelled. It can mix | blend as an agent.
By using such a temperature-sensitive polymer compound, after the temperature-sensitive polymer compound is coated with a gloss layer coating liquid in a temperature range where the temperature-sensitive polymer compound exhibits hydrophobicity (in this case, The layer can be thickened or gelled by changing the temperature to a temperature range in which the thermosensitive polymer compound exhibits hydrophilicity without being thickened or gelled.

As the thermosensitive polymer compound, (1) hydrophilicity in the temperature range below the temperature sensitive point (temperature at which the hydrophilicity / hydrophobicity changes), hydrophobicity at the temperature above the temperature sensitive point, conversely (2) Examples thereof are hydrophobic in the temperature range below the warm point and hydrophilic in the temperature range higher than the temperature sensitive point.
In the type (1), the coating layer can be thickened or gelled by applying a coating solution adjusted to a temperature higher than the temperature sensitive point and then cooling it to below the temperature sensitive point. In the type (2), conversely, after coating the coating liquid adjusted to a temperature lower than the temperature sensitive point, the coating layer is thickened or gelled by heating to a temperature higher than the temperature sensitive point. Can do.
In the type (2), since the water evaporates when the temperature is increased to thicken or gelate, it is relatively difficult to control the water content of the coating layer when the wetting liquid is applied. Therefore, in this invention, the type of (1) which can thicken or gelatinize a coating layer by lowering | hanging temperature after coating is especially suitable. Hereinafter, this type will be referred to.

The change in hydrophilicity / hydrophobicity of a thermosensitive polymer compound is, for example, in a system in which a thermosensitive polymer compound and water coexist, viscosity and transparency accompanying temperature change, and dissolution of the thermosensitive polymer compound in water. Appears as a sudden change in sex.
Therefore, for types that are hydrophilic in the temperature range below the temperature sensitive point and hydrophobic at temperatures above the temperature sensitive point, the temperature of the system in which the temperature sensitive polymer compound and water coexist is determined. In the temperature-viscosity curve when the temperature is gradually lowered from the temperature range where the water is hydrophobic (temperature above the temperature sensitive point), the transition point at which the viscosity changes suddenly (thickening) can be measured as the temperature sensitive point. it can.
In addition, when the temperature-sensitive polymer compound obtained in the temperature range where the temperature-sensitive polymer compound is hydrophobic (temperature above the temperature sensitive point) is gradually cooled, the dispersion becomes transparent. Alternatively, the temperature at which gelation starts can also be measured as a temperature sensitive point.

Although the temperature sensitive point of a thermosensitive polymer compound is not specifically limited, 0-30 degreeC, Especially 10-25 degreeC is preferable.
If a temperature sensitive point is 0 degreeC or more, a coating layer can be made into a temperature sensitive point comparatively easily, and the efficiency of thickening or gelatinization will become favorable. In addition, if it takes a long time to make the temperature less than the temperature sensitive point, the coating liquid may penetrate into the undercoat layer or the air-permeable support during that time, and a good gloss layer may not be formed, resulting in a decrease in gloss. . In addition, when the temperature sensitive point is 30 ° C. or higher, it is difficult to control the temperature during coating, and it is difficult to control the thickening or gelation uniformly, such as thickening or gelling simultaneously with coating. .

Examples of the temperature-sensitive polymer compound suitable for use include a temperature-sensitive polymer compound obtained by polymerization in the presence of polyvinyl alcohol and / or a derivative thereof disclosed in JP-A No. 2003-40916. It is done.
Specifically, in the presence of polyvinyl alcohol and / or its derivatives, a monomer (main monomer (M)) from which a polymer compound exhibiting temperature responsiveness (change in hydrophilicity / hydrophobicity) can be obtained by homopolymerization, and if necessary Examples thereof include a polymer compound obtained by polymerizing a monomer (submonomer (N)) that can be copolymerized therewith and cannot obtain a polymer compound exhibiting temperature responsiveness by homopolymerization.
Polyvinyl alcohol and / or its derivative, main monomer (M) and submonomer (N) can be used alone or in combination of two or more.

Examples of the polyvinyl alcohol include polyvinyl alcohol having a saponification degree of 96 to 100% (fully saponified polyvinyl alcohol), polyvinyl alcohol having a saponification degree of 76 to 95% (partially saponified polyvinyl alcohol), and the like. Examples of the polyvinyl alcohol derivative include modified polyvinyl alcohol such as silanol modification and cation modification, and polyvinyl alcohol introduced with a mercapto group or keto group. Although these polymerization degrees are not specifically limited, 300-4000 are preferably used.
The content of the polyvinyl alcohol and / or derivative thereof in the thermosensitive polymer compound is not particularly limited, but is 0.1 to 50% by mass, particularly 0.5 to 20% by mass, from the viewpoint of water resistance of the glossy layer. Is preferred.

Examples of the main monomer (M) include N-alkyl or N-alkylene substituted (meth) acrylamide derivatives and vinyl methyl ether.
Specifically, N-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-cyclopropyl (meth) acrylamide, N-ethyl (meth) acrylamide, N, N-diethylacrylamide, N, N-dimethyl (Meth) acrylamide, Nn-propyl (meth) acrylamide, N-methyl-Nn-propylacrylamide, N-methyl-N-isopropylacrylamide, N- (meth) acryloylpyrrolidine, N- (meth) acryloylpiperidine N-tetrahydrofurfuryl (meth) acrylamide, N-methoxypropyl (meth) acrylamide, N-ethoxypropyl (meth) acrylamide, N-isopropoxypropyl (meth) acrylamide, N-ethoxyethyl (meth) acrylamide, N (2,2-dimethoxyethyl) -N- methyl acrylamide, N- methoxyethyl (meth) acrylamide, N- (meth) acryloyl morpholine and the like.

Examples of the auxiliary monomer (N) include lipophilic vinyl compounds, hydrophilic vinyl compounds, and ionic vinyl compounds.
Here, as the lipophilic vinyl compound, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, glycidyl methacrylate, styrene, α-methylstyrene, ethylene, Examples include isoprene, butadiene, vinyl acetate, and vinyl chloride.
Examples of hydrophilic vinyl compounds include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, (meth) acrylamide, N-methylol acrylamide, diacetone acrylamide, methylene bisacrylamide, and 2-methyl-5-vinyl. Examples include pyridine, N-vinyl-2-pyrrolidone, N-acryloylpyrrolidine and the like.
The ionic vinyl compound contains carboxylic acid groups such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, crotonic acid, butenetricarboxylic acid, monoethyl maleate, monomethyl maleate, monoethyl itaconate, monomethyl itaconate, etc. Monomer, sulfonic acid group-containing monomer such as 2-acrylamido-2-methyl-propanesulfonic acid, styrenesulfonic acid, vinylsulfonic acid, (meth) acrylsulfonic acid, N, N-dimethylaminoethyl (meth) acrylate, N, Examples include amino group-containing monomers such as N-diethylaminoethyl (meth) acrylate.

  The copolymerization ratio of the main monomer (M) and the submonomer (N) used as necessary is not particularly limited, but if the ratio of the submonomer (N) is too large, the temperature responsiveness will not be exhibited. The proportion of the secondary monomer (N) in the conductive polymer compound is preferably 50% by mass or less, particularly preferably 30% by mass or less.

The thermosensitive polymer compound is preferably blended in the gloss layer coating liquid in the form of a polymer emulsion. Such polymer emulsions are commercially available, for example, from Asahi Kasei Corporation under trade names such as ALB-213 and ALB-221.
It can also be prepared and used. The polymer emulsion can be prepared by the method described in JP-A-2003-040916. That is, it can be prepared by performing a polymerization reaction using the above-described monomer in the presence of polyvinyl alcohol and / or a derivative thereof at a temperature equal to or higher than the temperature sensitive point of the thermosensitive polymer compound. More specifically, there is a method in which an emulsifier is dissolved in water, and emulsion polymerization is carried out by adding polyvinyl alcohol and / or a derivative thereof and a main monomer (M), if necessary, a submonomer (N), a radical polymerization initiator. Can be mentioned. Monomers and radical polymerization initiators can be added all at once, continuously, or dividedly.

A gloss layer coating solution for the second production method can be prepared by mixing the polymer emulsion and other components such as a pigment.
Water is preferably used as the solvent for the coating solution, but adjustment of the temperature sensitive point of the thermosensitive polymer compound and slowing of drying at the time of casting finish to obtain a gloss layer with good printability, etc. For this reason, an organic solvent can be used instead of water, or water and an organic solvent can be used in combination.
The gloss layer coating liquid is preferably maintained at a temperature equal to or higher than the temperature sensitive point until it is applied after preparation.

  After coating the above coating liquid on an air-permeable support or an undercoat layer provided as necessary to form a coating layer, the temperature is less than the temperature sensitive point in an undried or slightly dried state. Cool to the temperature of. Although there is no restriction | limiting in particular as a cooling method, It can cool using a cold air machine, a cooling roll, a low temperature gas, etc. By cooling, the coating layer thickens or gels. Excessive cooling makes the degree of gelation too strong and may impair the glossiness. Therefore, it is preferable to cool within the range of a temperature 10 ° C. lower than the temperature sensitive point to the temperature sensitive point.

In addition, the base surface (the surface of the air-permeable support or the undercoat layer) on which the gloss layer is formed is previously less than the temperature sensitive point, particularly 10 ° C. from the temperature sensitive point, with cold air or a treatment liquid having a temperature lower than the temperature sensitive point. It is preferable to cool to a lower temperature. Thereby, the cooling efficiency after coating can be increased. In particular, a method of directly applying a treatment liquid having a temperature lower than the temperature sensitive point to the base surface is preferable because the base surface can be quickly cooled. Further, from the viewpoint of the cooling efficiency of the coating layer, it is preferable to apply the gloss layer coating liquid while the treatment liquid is not dried.
By adopting such a procedure, after coating, the coating layer can be quickly thickened or gelled, and as a result, it is excellent in printability for inkjet recording and the like, and is also good for pigment inks. A gloss layer exhibiting printability can be formed.

  As the treatment liquid, water, an organic solvent, or the like is used, and water is preferably used from the viewpoint of ease of use. It is preferable to add a cationic compound or a preservability improver to the treatment liquid because the components penetrate into the support or the undercoat layer, and an effect of improving water resistance and heat and moisture bleeding is seen. In addition, auxiliary agents such as a crosslinking agent such as a boron compound and a zirconium compound, a pH adjuster, a surfactant, an antifoaming agent, and an antiseptic can be added.

  In the above, (1) the case of using a thermosensitive polymer compound that exhibits hydrophilicity in the temperature range below the temperature sensing point and hydrophobicity at a temperature above the temperature sensing point has been described, but (2) the temperature below the temperature sensing point. A temperature-sensitive polymer compound that exhibits hydrophobicity in the region and hydrophilicity in the temperature region higher than the temperature-sensitive point can be similarly applied. Examples of this type of thermosensitive polymer compound include compounds disclosed in JP-A-8-244334.

In the first production method, the moisture content of the coating layer is 12 to 40% by mass. In the second production method, after the coating layer is thickened or gelled, the moisture content is 12% by mass or more. Then, a wetting liquid is applied to the surface.
The wetting liquid is not particularly limited as long as it can wet the surface of the coating layer, but water or the like is preferably used. Moreover, if the mold release property from the heating mirror surface at the time of cast finishing is taken into consideration, water containing a mold release agent is preferably used.

  The release agent can be included in the wetting liquid, in the glossy layer coating liquid, or applied to the heated mirror surface, and these can also be combined. Since it is easy to express good releasability with a small amount of use, it is particularly preferable to include it in the wetting liquid.

The release agent is not particularly limited, but higher fatty acid esters such as potassium stearyl phosphate, higher fatty acid amides such as stearic acid amide and oleic acid amide, polyolefin waxes such as polyethylene wax, oxidized polyethylene wax and polypropylene wax, Examples thereof include higher fatty acid alkali salts such as calcium phosphate, zinc stearate, potassium oleate and ammonium oleate, silicone compounds such as lecithin, silicone oil and silicone wax, and fluorine compounds such as polytetrafluoroethylene. These can use 1 type (s) or 2 or more types.
Of these, higher fatty acid amides are preferably used because they are excellent in releasability and have the effect of suppressing printing bleeding. In particular, when a cationic compound is contained in the glossy layer and / or the wetting liquid, the effect is remarkable.

  Although there is no restriction | limiting in particular in the usage-amount of a mold release agent, When making it contain in a wetting liquid, 0.05-20 mass%, Furthermore, 0.1-10 mass%, Especially 0.1-5 mass% is preferable. When it is contained in the glossy layer, it is preferably 0.1 to 50 parts by mass, more preferably 0.3 to 30 parts by mass, and particularly preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the pigment. When the blending amount is small, the effect of improving the releasability is not sufficiently exhibited, and when the blending amount is large, the glossiness may be lowered, the ink repellency, the print density may be lowered, and the like.

The wetting liquid may further contain a cationic compound, a storage stability improving agent, and the like. Each of these can be used alone or in combination of two or more.
By adding a cationic compound to the wetting liquid, printing water resistance and printing density can be improved. As the cationic compound, those exemplified for the ink fixing agent for the glossy layer are used.
The storage stability of printing can be improved by adding a storage stability improver to the wetting liquid. Specific examples thereof include water-soluble polyvalent metal salts such as aluminum compounds such as polyaluminum chloride, zirconium compounds such as ammonium zirconium carbonate and zirconium acetate, bis [2- (2-hydroxyethylthio) ethyl] sulfone, Examples include sulfur-containing compounds such as 2- (phenylthio) ethanol, ultraviolet absorbers such as benzotriazole and cerium oxide, antioxidants such as ascorbic acid, vitamin E, dibutylhydroxytoluene, and rutin, and radical scavengers such as hindered amines. . Among them, bis [2- (2-hydroxyethylthio) ethyl] sulfone is preferable because gas resistance of ink jet printing is improved.

For the wetting liquid, if necessary, synthetic resin latex such as styrene-butadiene latex and methyl methacrylate-butadiene copolymer latex, proteins such as casein, soy protein, synthetic protein, various starches such as starch and oxidized starch , Polyvinyl alcohol, cellulose derivatives such as carboxymethylcellulose and methylcellulose, polycarboxylic acid, polyacrylic acid, acrylic emulsion, polyamide, polyester, various thickeners such as alkali thickeners and nonionic surfactants, and flow modifiers , Sodium chloride, ammonium chloride, zinc chloride, magnesium chloride, sodium sulfate, potassium sulfate, ammonium sulfate, zinc sulfate, magnesium sulfate, ferrous sulfate, sodium nitrate, ammonium nitrate, sodium monophosphate, ammonium phosphate, Calcium acid, sodium polyphosphate, sodium hexametaphosphate, sodium formate, ammonium formate, sodium acetate, potassium acetate, sodium monochloroacetate, sodium malonate, sodium tartrate, potassium tartrate, potassium citrate, sodium lactate, sodium gluconate, adipic acid Ammonium salts and metal salts of inorganic and organic acids such as sodium, sodium dioctylsulfosuccinate and sodium aluminate, as well as amines such as methylamine, diethylenetriamine, diisopropylamine, ethanolamine, diethanolamine and triethanolamine, phosphoric acid Esters, polyoxyethylene alkylphenol ether phosphates, polyoxyethylene ether phosphates, alkylphenols Phosphate esters such as ether phosphate ester salts, polyoxyethylene alkyl ether, polyoxyethylene, aqueous ammonia, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, adipic acid Add one or more additives such as polyfunctional epoxy compounds such as diglycidyl ester, various water-proofing agents such as urea-formaldehyde, polyamide-epichlorohydrin, glyoxal, and printing suitability improver can do.
These addition amounts are not particularly limited, but are preferably 0.05 to 10% by mass, particularly 0.1 to 5% by mass in the wetting liquid.

  If necessary, various additives such as a dispersant, an antifoaming agent, a colorant, a fluorescent dye, an antistatic agent, and an antiseptic can be added to the wetting liquid. In addition, pigments such as alumina, silica, clay and calcium carbonate can be added as an auxiliary agent.

  The wetting liquid may be applied all at once, or may be applied in multiple portions. By dividing into a plurality of times, for example, a combination of a plurality of additives that aggregate when mixed can be applied as a wetting liquid.

Application amount of the wetting liquid is not particularly limited, about 5~50ml / ^{m 2} is preferred. If the application amount of the wetting liquid is too small, plasticization of the coating layer becomes insufficient, and good glossiness may not be exhibited. If the application amount of the wetting liquid is too large, the amount of water evaporated on the heating mirror surface becomes too large, and good glossiness may not be exhibited.
The method of applying the wetting liquid is not particularly limited, and can be carried out using a coating apparatus such as various coaters as in the coating of the gloss layer coating liquid (see paragraph [0060]). Since it is obtained, it is preferable to apply the wetting liquid simultaneously at the time of cast finishing, that is, when passing between the heated mirror surface and the press roll disposed opposite thereto.

  In both the first and second manufacturing methods, after applying a wetting liquid to the surface of the coating layer, the coating layer is pressed against a heated mirror surface (usually a cast drum) to perform cast finishing. The coating layer is dried at the same time as glossiness is imparted to the surface by pressure contact with the heated mirror surface.

The temperature of the heating mirror surface is not particularly limited, but is preferably 80 to 120 ° C. If the temperature of the heated mirror surface is less than 80 ° C, the drying effect is poor and the productivity may be reduced. If the temperature exceeds 120 ° C, the coating liquid may bump on the heated mirror surface and the glossiness and printability may be reduced. There is.
Moreover, when using a temperature sensitive polymer compound for a glossy layer, it is preferable to set the temperature of a heating mirror surface to the temperature within +/- 20 degreeC of the glass transition temperature of a temperature sensitive polymer compound. When the glass transition temperature of the thermosensitive polymer compound is lower than the temperature of the heating mirror surface by more than 20 ° C., the glossy layer is formed too much during drying, resulting in a decrease in the voids on the surface and a decrease in ink absorbency. There is a fear. On the other hand, when the glass transition temperature of the thermosensitive polymer compound is higher than the temperature of the heating mirror surface by 20 ° C., the film formation becomes insufficient, the remaining amount of voids increases, and the glossiness becomes insufficient. There is a fear.

  In addition, when sufficient drying cannot be performed only by press-contacting to the heating mirror surface, preliminary drying may be performed so that the moisture content of the coating layer does not become less than 12% by mass before casting finish. . Moreover, you may implement auxiliary drying by auxiliary drying means, such as a near-infrared dryer, during cast finishing or after finishing.

A layer other than the above can be provided on the cast coating sheet as required.
For example, a back surface layer containing a resin and, if necessary, a pigment or a dye can be provided on the back surface side for the purpose of preventing curling or the like, adjusting the frictional properties, adjusting the touch / feel. As resin, it is excellent in curling prevention effect at the time of ink-jet printing and improvement in printer transportability, and since the printing texture can be brought close to photographic paper, polyolefin (polyethylene, polypropylene, etc.), polyester (polyethylene terephthalate, etc.) Etc.) is preferably used.
Such a back layer can be formed by a coating method or a laminating method. Although there is no restriction | limiting in particular in the formation timing of a back surface layer, After cast finish is preferable.

As described above, a cast coated sheet having a gloss layer is produced.
According to the first and second production methods of the present invention, it is possible to stably provide a cast coated sheet that is excellent in both glossiness and inkjet printing suitability and suitable for inkjet recording. The cast coating sheet obtained in the present invention can be subjected to beautiful ink jet printing such as photographic tone regardless of the type of ink (dye type, pigment type) used.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, this invention is not limited at all by the following example. In the examples, “parts” and “%” are based on mass unless otherwise specified.

(Preparation of air-permeable support)
First, 100 parts of wood pulp (LBKP: freeness 440 ml CSF), 15 parts of filler (mixture of calcium carbonate 3: talc 1), commercially available sizing agent (trade name: Fibran 81K, manufactured by NSC Japan) 0. Paper was made with a long paper machine using 05 parts, 0.45 parts of sulfuric acid band, 0.45 parts of starch, 0.4 parts of paper strength enhancer (polyamide / epichlorohydrin resin) and a little yield improver. The basis weight was 192 g / m ² . This paper was subjected to a supercalender treatment at a linear pressure of 150 kg / cm to obtain a gas-permeable support (base paper). The thickness of this support was 205 μm, and the Oken air permeability was 30 seconds / 100 cc.

(Preparation of coating solution for undercoat layer)
Synthetic amorphous silica (trade name: Fine Seal X-60, manufactured by Tokuyama Co., Ltd., average secondary particle size 6.2 μm) as a pigment, silyl-modified polyvinyl alcohol (trade name: R1130, Kuraray ( Co., Ltd.) 25 parts, fluorescent dye (trade name: Whitetex BPS (H), manufactured by Sumitomo Chemical Co., Ltd.) 2 parts, and water were mixed to prepare an undercoat layer coating solution. The solid content concentration was 15%.

(Preparation of cationic fine pigment)
Commercially available vapor phase silica (trade name: Leolosil QS-30, average primary particle size 9 nm, specific surface area 300 m ² / g, manufactured by Tokuyama Corporation) was dispersed and pulverized with a sand grinder, then nanomizer (trade name: Nanomizer, Using a nanomizer), pulverization and dispersion were repeated, and after classification, a 10% silica dispersion having an average secondary particle size of 80 nm was prepared.
10 parts of diallyldimethylammonium chloride-acrylamide copolymer (trade name: PAS-J-81, manufactured by Nitto Boseki Co., Ltd.) is added as a cationic compound to the dispersion to agglomerate the pigment and increase the dispersion. After causing viscosity, pulverization and dispersion were repeated using a nanomizer again to prepare a 12% silica dispersion having an average secondary particle size of 300 nm, thereby obtaining a cationic fine pigment.

(Preparation of gloss layer coating solution)
・ Glossy layer coating liquid A
100 parts of the above-mentioned cationic fine pigment, 20 parts of polyvinyl alcohol (trade name: PVA145, manufactured by Kuraray Co., Ltd.) as an adhesive, 0.1 part of an antifoaming agent, and water are mixed, and a coating liquid A for glossy layer is obtained. Prepared. The solid content concentration was 10%.
・ Glossy layer coating liquid B
Under 40 ° C., 100 parts of the above-mentioned cationic fine pigment, a thermosensitive polymer compound as an adhesive (trade name: ALB-221, manufactured by Asahi Kasei Co., Ltd., temperature sensitive point 24 ° C., hydrophilic below the temperature sensitive point, Gloss layer coating solution B was prepared by mixing 20 parts of hydrophobicity above the temperature sensitive point), 0.1 part of antifoaming agent and water. The solid content concentration was 10%.
・ Glossy layer coating liquid C
Under 50 ° C., 100 parts of the above-mentioned cationic fine pigment, thermosensitive polymer compound as an adhesive (trade name: ALB-213, manufactured by Asahi Kasei Co., Ltd., temperature sensitive point 32 ° C., hydrophilic at a temperature sensitive point below, Gloss layer coating solution C was prepared by mixing 20 parts of hydrophobicity above the temperature sensitive point), 0.1 part of antifoaming agent and water. The solid content concentration was 10%.

(Preparation of wetting liquid)
A 1% aqueous solution of stearamide release agent was prepared as a wetting liquid.

(Examples and comparative examples)
In any of the examples, on the air-permeable support, the coating solution for the undercoat layer is applied with an air knife coater so as to have an absolutely dry mass of 5 g / m ² , thereby forming a coating layer. Was dried at 120 ° C. for 1 minute to form an undercoat layer. On this, the glossy layer was formed under different conditions. Hereinafter, the procedure for forming the glossy layer in each example will be described.

(Example 1)
After adjusting the surface temperature of the undercoat layer to 23 ° C., the above gloss layer coating solution A (adjusted to 23 ° C.) is applied at 5 g / m ^{2 in} an absolutely dry mass with a die coater. A layer was formed. After coating, no aggressive drying was performed. Subsequently, the above wetting liquid (23 ° C.) was applied to the surface of the coating layer at 20 ml / m ² . The moisture content of the coating layer at the time of applying the wetting liquid was 22%. Immediately after the application of the wetting liquid, the coating layer was pressed against a cast drum having a surface temperature of 100 ° C. to give gloss and dry to obtain a cast coated sheet of the present invention.

(Example 2)
A cast coated sheet of the present invention was obtained in the same manner as in Example 1 except that the coating layer was dried with a hot air dryer until the moisture content reached 14% and then the wetting liquid was applied.
(Comparative Example 1)
A cast coating sheet for comparison was obtained in the same manner as in Example 1 except that the coating layer was dried with a hot air dryer until the water content became 5% and then the wetting liquid was applied.
(Comparative Example 2)
As in Example 1, except that a coating liquid (adjusted to 23 ° C.) obtained by diluting the gloss layer coating liquid A to a solid content concentration of 5% was used instead of the gloss layer coating liquid A. A cast coated sheet was obtained. The moisture content of the coating layer when the wetting liquid was applied was 42%.

(Example 3)
A cast coated sheet of the present invention was obtained in the same manner as in Example 1 except that pure water (23 ° C.) was used as the wetting liquid. The moisture content of the coating layer at the time of applying the wetting liquid was 22%.

(Example 4)
After adjusting the surface temperature of the undercoat layer to 23 ° C., an aqueous borax solution (solid content: 3%, 23 ° C.) was coated on the layer at a dry weight of 1 g / m ² and dried at 23 ° C. for 30 seconds. After that, the gloss layer coating liquid A (adjusted to 23 ° C.) was applied at a dry mass of 5 g / m ^{2 with} a die coater to form a coating layer. The coating layer gelled immediately after coating. The water content of the coating layer after gelation was 23%. Then, like Example 1, application | coating of a wetting liquid and cast finishing were implemented, and the cast coating sheet of this invention was obtained.
(Comparative Example 3)
A cast coating sheet for comparison was obtained in the same manner as in Example 4 except that the coating layer after gelation was dried by a hot air dryer until the moisture content was 5%, and then the wetting liquid was applied. .

(Example 5)
On the undercoat layer, the above glossy layer coating solution B (adjusted to 35 ° C.) was applied at a dry mass of 5 g / m ^{2 with} a die coater to form a coating layer. Then, it cooled to the temperature of 20 degreeC using the cold air machine, and the coating layer was gelatinized. The moisture content of the coating layer at this time was 20%. Then, like Example 1, application | coating of a wetting liquid and cast finishing were implemented, and the cast coating sheet of this invention was obtained.
(Comparative Example 4)
A cast coating sheet for comparison was obtained in the same manner as in Example 5 except that the wet coating was applied after the gelled coating layer was dried by a hot air dryer until the water content became 5%. .

(Example 6)
On the undercoat layer, the above gloss layer coating liquid C (adjusted to 45 ° C.) was applied at 5 g / m ^{2 in} an absolutely dry mass with a die coater to form a coating layer. Then, it cooled to the temperature of 20 degreeC using the cold air machine, and the coating layer was gelatinized. The moisture content of the coating layer at this time was 21%. Then, like Example 1, application | coating of a wetting liquid and cast finishing were implemented, and the cast coating sheet of this invention was obtained.

(Evaluation items and evaluation methods)
"Glossiness"
The gloss layer surface of the obtained cast coated sheet was visually observed from the lateral direction and evaluated according to the following criteria.
A: Extremely high gloss.
◎ to ○: Between ◎ and ○.
○: High gloss.
Δ: Glossy.
X: The glossiness is slightly inferior.
XX: Matte without gloss.

"Print density"
Solid black printing was performed using a commercially available dye ink type ink jet printer (trade name: PM-G800, manufactured by Seiko Epson Corporation), and the printing density was measured with a Macbeth reflection densitometer (Macbeth RD-914). .

"Print blur"
Using the same printer as the print density evaluation, black, cyan, magenta, yellow, red, green, and blue solid colors are printed in a grid pattern so that the borders are in contact with each other. The blur was visually evaluated.
A: Printing blur is not observed at all, and it is very good.
○: Slight bleeding is observed, but there is no practical problem.
Δ: Slight printing blurring, practically a problem.
X: Printing blur is remarkably problematic for practical use.

"Uniformity of solid printing (solid uniformity)"
Printing was performed using the same printer as the evaluation of the printing density, and the printing unevenness (darkness unevenness) of the green solid printing portion was visually evaluated.
A: Printing unevenness is not recognized at all and is extremely good.
○: Printing unevenness is slightly observed, but there is no practical problem.
Δ: Slightly uneven printing, slightly problematic in practical use.
X: There is uneven printing, which is extremely problematic in practical use.

(result)
The results are shown in Table 1. The table also describes the main conditions for forming the glossy layer.
As shown in the table, in Examples 1 to 3 to which the first production method of the present invention was applied and Examples 4 to 6 to which the second production method of the present invention was applied, the moisture content of the coating layer Was applied in a state of 14 to 23%, and then cast finish was performed to form a glossy layer.
In any of the examples, a cast coated sheet having excellent glossiness was obtained, and the obtained cast coated sheet was free from printing blur or at a level that would not cause a problem. The uniformity of the ink was good and the ink-jet printing suitability was good.

Among them, those in which the coating layer is gelled (Examples 4 and 5), particularly those in which gelation is performed using a thermosensitive polymer compound (Example 5), those that are not so (Examples 1 to 3). ), The glossiness was more excellent, and the roundness of the ink dots when printed with dye ink was also better. However, when the temperature sensitive point of the thermosensitive polymer compound used exceeds 30 ° C. (Example 6), the glossiness is relatively inferior to that of 0-30 ° C. (Example 5). It was.
In addition, when a wetting liquid containing no release agent was used (Example 3), the gloss was slightly inferior to that when using a wetting liquid containing a release agent (Example 1).

  On the other hand, in Comparative Examples 1 to 4 in which the moisture content at the time of applying the wetting liquid was 5% by mass or 42% by mass (Comparative Example 1 corresponds to the rewet casting method), the glossiness was remarkably poor. In comparison, the uniformity of the solid printing tended to be inferior.

  The cast coated sheet obtained by the technique of the present invention includes various recording sheets such as ink jet recording sheets, heat-sensitive recording sheets, pressure-sensitive recording sheets, thermal transfer recording sheets, and electrophotographic recording sheets, art paper, coated paper, and cast coated paper. It can preferably be used as a coating sheet for printing.

Claims (6)

  A glossy layer is formed by forming a coating layer having a water content of 12 to 40% by mass on a gas-permeable support, applying a wetting liquid to the surface of the layer, and then pressing and drying on a heated mirror surface. A method for producing a cast coated sheet characterized by the above.   After forming the coating layer by coating the gloss layer coating liquid on the air-permeable support, the layer is thickened or gelled, and the moisture content of the layer is 12% by mass or more. A method for producing a cast coated sheet, wherein a gloss layer is formed by applying a wetting liquid to the surface, pressing it against a heated mirror surface and drying. Glossy layer coating that contains a thermosensitive polymer compound that is hydrophilic in a specific temperature range, hydrophobic in a temperature range different from that, and thickens or gels in liquids containing the hydrophilicity in a temperature range that exhibits hydrophilicity. Using liquid,
After forming the coating layer by applying the gloss layer coating liquid in a temperature range where the temperature sensitive polymer compound exhibits hydrophobicity, the temperature range in which the temperature sensitive polymer compound exhibits hydrophilicity The method for producing a cast coated sheet according to claim 2, wherein the layer is thickened or gelled by changing the temperature.   The temperature-sensitive polymer compound is hydrophilic at a temperature lower than the temperature-sensitive point and hydrophobic at a temperature higher than the temperature-sensitive point, and has a temperature-sensitive point of 0 to 30 ° C. The manufacturing method of the cast coating sheet of description.   The method for producing a cast coated sheet according to any one of claims 1 to 4, wherein the cast coated sheet is for inkjet recording.   A cast coated sheet produced by the method for producing a cast coated sheet according to claim 1.