JP2006212885A - Glossy inkjet recording sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide glossy inkjet recording sheet used in common for a dye ink and a pigment ink which has a good recording suitability for the dye ink and also excels in the ink absorbing properties, printing density and a printing gloss in regard to the pigment ink. <P>SOLUTION: This glossy inkjet recording sheet has an undercoat layer and an ink accepting layer having a cast-finished surface on a paper substrate. The undercoat layer contains amorphous silica having an average secondary particle diameter of 3-5 μm and an adhesive and a dry coating amount of the layer is 7-9 g/m<SP>2</SP>. The ink accepting layer contains amorphous silica having an average secondary particle diameter of 90-700 nm, polyvinyl alcohol having a polymerization degree of 4,000-7,000 and a diallyl dimethylammonium chloride-acrylamide copolymer having a mass average molecular weight of 150,000-300,000, and its dry coating amount is 10-20 g/m<SP>2</SP>. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to glossy inkjet recording paper.

  Inkjet recording method that forms images by ejecting water-based ink from fine nozzles is easy to make full color, high-speed recording is possible, and it is cheaper than other printing devices by printing a small number of copies, etc. For this reason, it is widely used in terminal printers, facsimiles, plotters, form printing, and the like.

In recent years, rapid spread of printers and higher definition and higher speed have progressed, and accordingly, ink jet recording papers are required to have higher ink absorption speed than before.
Furthermore, there is a strong demand for the realization of high image quality comparable to silver halide photography for recorded images taken with a digital camera.
Further, in order to bring the quality of the printed image closer to the quality of the photograph, further improvement in the color density and glossiness of the printed image is desired.

On the other hand, in order to realize image storability equivalent to that of silver salt photographs, improvement of the ink itself has been proposed.
Along with water-based dye inks (hereinafter referred to as dye inks) that use highly hydrophilic colorants that occupy the mainstream of conventional inkjet recording inks, hydrophobic color pigments with excellent water resistance and light resistance are used as colorants. Ink containing ink (hereinafter referred to as pigment ink) is also often used.
The colored pigment in the pigment ink tends to stay on the coated surface, and the high gloss inkjet recording paper for the dye ink that has been used so far is inferior in fixability and scratching property of the pigment ink.
For this reason, there is a strong demand for ink jet recording paper capable of printing with high image quality for both dye ink and pigment ink.

  In order to achieve this, fine pigment is used in the ink receiving layer, and the peak in the pore diameter distribution curve of the coating layer is controlled to about 0.1 μm or less to suppress cracking of the coating film and Techniques for obtaining higher ink absorption speed and gloss, such as reproducing roundness, are essential.

As a technique for obtaining a high ink absorption speed and gloss, for example, an ink jet recording paper that includes inorganic pigment fine particles having an average primary particle diameter of 20 nm or less and a binder polyvinyl alcohol in an ink recording layer has been proposed. (For example, see Patent Documents 1 and 2.)
Patent Document 1 discloses that the coating film is cracked by using a cross-linking reaction between borax or boric acid and polyvinyl alcohol before the ink recording layer exhibits a reduced drying rate. It is described that a high coating amount is imparted while suppressing. According to the invention of Patent Document 1, the roundness of dots is reproduced, and excellent image quality can be obtained in dye ink.
However, in the invention of Patent Document 1, the surface glossiness of the surface layer of the inkjet recording paper is insufficient. Further, the ink absorptivity when the pigment ink is used is not yet sufficient.
In Patent Document 2, an undercoat layer on which boric acid or a boron compound is applied in an amount of 0.1 g / m ² or more per surface of the support is provided on the support surface between the support and the ink recording layer. Is described. According to the invention of Patent Document 2, the polyvinyl alcohol in the ink recording layer is cross-linked by boric acid or a boron compound in the undercoat layer, and the paint is applied before the ink recording layer shows a reduced drying rate. Gelation can suppress cracking of the coating film.
However, even in the invention of Patent Document 2, the glossiness of the surface of the obtained ink jet recording paper is not yet satisfactory.

In addition, after the first porous layer is applied to a non-water-absorbing support and dried, or before the completion of drying, bubbles are generated on the film surface produced by applying the second porous layer. Inkjet recording paper has been proposed. By this manufacturing method, an ink recording layer free from bubbles and cracks can be obtained (see Patent Document 3).
However, the gloss and ink absorption speed of the ink jet recording paper have not been sufficient yet.

In addition, a method of manufacturing an ink jet recording paper using a water-absorbing base paper as a support has been proposed (see Patent Documents 4 and 5).
Japanese Patent Application Laid-Open No. H10-228561 discloses a paper in which a borax or boric acid treatment layer and an ink receiving layer are sequentially provided on the glossy surface of single glossy paper.
However, since wet silica having an average particle diameter of 1 μm or more is used for the ink receiving layer, gloss and print density have not been improved.
In Patent Document 5, an ink receiving layer of 5 to ²⁰ g / m ² is provided on one of a base paper obtained by applying borax or boric acid at a level of 0.1 g / m ² or more per side and a coated surface of the base paper. Inkjet recording paper is mentioned.
However, since wet silica having an average particle size of 1 μm or more is also used for the ink receiving layer, high gloss and print density are not obtained.

As a technique for imparting gloss, for example, an attempt has been proposed to provide a glossy expression layer containing colloidal particles and a polymer latex on an ink recording layer mainly composed of a micron order pigment. With this configuration, a certain level of gloss can be obtained (see Patent Document 6).
However, since the dye in the ink is fixed on the micron-order ink recording layer, the printing density is low and the uniformity of the image is inferior. In addition, since the peak in the pore distribution curve of the glossy layer is larger than 0.1 μm, the glossy layer is cracked, the visual gloss is low, and the print density of the pigment ink is inferior.

In order to further increase the gloss, a method has been proposed in which the glossy layer is pressed against a heated mirror drum while wet and the mirror surface is copied. By this method, a certain level of gloss can be obtained (see Patent Document 7).
However, since the glossy layer has cracks, the uniformity of the image is inferior, and the print density and the suitability of the pigment ink have not been solved.

In addition, two or more recording layers are provided on the base material, and the outermost layer using an aggregate pigment having an average particle diameter of 1 μm or less is pressure-bonded to a heated mirror drum while being wet and cast. Attempts have been made to solve problems such as gloss, print density, and ink absorbency (see Patent Document 8).
However, since the peak in the pore diameter distribution curve of the outermost layer is not less than 0.1 μm and the cracks of the outermost layer are not controlled, the dots after printing lack roundness and the print density is insufficient. However, the uniformity of the image was also low.
In addition, with recent high-definition and high-speed printers, ink absorbency has been insufficient.
For this reason, when pigment ink is used, a large amount of colored pigment is absorbed in the cracked portion of the coating film, resulting in unevenness in the image and low printing density, which is inappropriate.
Japanese Patent Laid-Open No. 11-115308 JP 2001-246832 A JP 2000-301828 A JP-A-5-104848 Japanese Patent Publication No. 7-37175 Japanese Patent Laid-Open No. 7-101142 Japanese Unexamined Patent Publication No. 7-117335 JP 2001-10220 A

  The present invention has been made in view of the above circumstances, and not only has good recording properties for dye inks, but also dye inks and pigment inks excellent in ink absorbability, print density, and print gloss of pigment inks. An object is to provide a common glossy inkjet recording paper.

As a result of repeated studies, the present inventors have found that these problems can be solved by providing an undercoat layer containing a specific component and an ink receiving layer on a paper support, thereby completing the present invention. It came to.
The present invention includes the following embodiments.
[1] A glossy inkjet recording paper having an undercoat layer and an ink-receiving layer whose surface is cast-finished on a paper support, the undercoat layer comprising amorphous silica having an average secondary particle size of 3 to 5 μm And an adhesive, and a dry coating amount of 7 to 9 g / m ^2. The ink receiving layer has amorphous silica having an average secondary particle size of 90 to 700 nm, and a polymerization degree of 4000. It is a layer containing ˜7000 polyvinyl alcohol and a diallyldimethylammonium chloride-acrylamide copolymer having a weight average molecular weight of 150,000 to 300,000 and a dry coating weight of 10 to 20 g / m ^2. Glossy inkjet recording paper.
[2] The glossy ink jet recording paper according to [1], wherein the content of polyvinyl alcohol in the ink receiving layer is 10 to 20 parts by mass with respect to 100 parts by mass of amorphous silica.

  According to the present invention, it is possible to obtain a glossy ink jet recording paper for dye ink and pigment ink that is excellent in ink absorbability, print density, and print gloss of pigment ink as well as good recording properties for dye ink. it can.

The glossy ink jet recording paper of the present invention is a glossy ink jet recording paper having an undercoat layer and an ink receiving layer whose surface is cast-finished on a paper support.
Hereinafter, the paper support, the undercoat layer, and the ink receiving layer will be described in detail.

<Paper support>
The glossy inkjet recording paper of the present invention uses paper as a support.
As the paper support, a known paper base that is usually used can be used as long as the effects of the present invention are not impaired. For example, fine paper, art paper, coated paper, cast coated paper, foil paper, Kraft paper, baryta paper, paperboard, impregnated paper, vapor-deposited paper, water-soluble paper, acid paper used for general coated paper, neutral paper, and the like are appropriately used.
The paper base material contains wood pulp as a main component, and fillers, various auxiliaries and the like are added as necessary.

As the wood pulp, various chemical pulps, mechanical pulps, recycled pulps and the like can be used. These pulps can be adjusted in the beating degree (freeness) by a beating machine in order to adjust paper strength, papermaking suitability, and the like.
In order to improve smoothness, it is desirable to advance freeness. On the other hand, in many cases, better results are obtained when the freeness is not advanced with respect to the blurring of the paper and the bleeding of the recorded image caused by the moisture in the ink.
The pulp freeness is preferably 250 to 550 ml (CSF: JIS-P-8121), more preferably 300 to 500 ml.

The filler added to the paper base material is blended for the purpose of imparting opacity or the like or adjusting the ink absorbability. For example, calcium carbonate, calcined kaolin, silica, titanium oxide and the like are preferably used. Among these, calcium carbonate is preferable because a paper base material with high whiteness is obtained and glossiness of the ink jet recording paper is enhanced.
As for the content rate (ash content) of the filler in a paper base material, about 1-20 mass% is preferable. If the filler content is 1% by mass or more, the air permeability of the paper substrate is good, and if the filler content is 20% by mass or less, sufficient paper strength is obtained.
A more preferable filler content is 7 to 20% by mass. Within this range, smoothness, air permeability, and paper strength are balanced, and it becomes easy to obtain a glossy inkjet recording paper excellent in glossiness and image sharpness.

Examples of the auxiliary agent added to the paper substrate include a sizing agent, a fixing agent, a paper strength enhancer, a cationizing agent, a yield improver, a dye, and a fluorescent brightening agent.
As the paper strength enhancer, polyamide / epichlorohydrin resin, N-vinylformamide / vinylamine copolymer and the like are preferably used. Among these, polyamide epichlorohydrin resin is preferably used because it has the effect of improving the dimensional stability of paper when wet. The paper strength enhancer can be added to the paper substrate by a process such as internal addition, coating, or impregnation.
Furthermore, in the size press process of the paper machine, the surface strength, sizing degree, etc. can be adjusted by applying and impregnating starch, polyvinyl alcohols, cationic resins, etc. to the paper substrate.

The steecht degree of the paper support (100 g / m ² paper) is preferably about 1 to 200 seconds, and more preferably 4 to 120 seconds.
If the Steecht sizing degree is 1 second or more, there will be no operational problems such as wrinkling during coating. If the Steecht sizing degree is 200 seconds or less, good ink absorbability is exhibited and printing is performed. Later curls and cocklings disappear.
The basis weight of the paper substrate is not particularly limited, but is preferably about ²⁰ to 400 g / m ² .

The Oken type air permeability of the paper support is preferably 10 to 350 seconds. 10 to 200 seconds are more preferable, and 20 to 100 seconds are more preferable.
If the air permeability is 10 seconds or more, the undercoat layer coating solution can be prevented from penetrating into the paper support. If the air permeability is 350 seconds or less, it is possible to improve the problem that the operability is inferior when press-finishing the cast drum.

<Undercoat layer>
In the glossy inkjet recording paper of the present invention, an undercoat layer is provided on a paper support.
The undercoat layer contains amorphous silica having an average secondary particle diameter of 3 to 5 μm and an adhesive.
By providing this undercoat layer on a paper support, the glossy ink jet recording paper of the present invention has good ink absorptivity, and is excellent in printing density, printing bleeding, solid uniformity, and the like.

[Pigment]
For the undercoat layer, amorphous silica having an average secondary particle diameter of 3 to 5 μm is used.
The average secondary particle diameter in the present invention is a particle diameter obtained by observing an aqueous silica dispersion with an electron microscope (SEM, TEM) (taken an electron micrograph of 10,000 to 400,000 times, and silica dispersion in a 5 cm square. The particle diameter is measured and averaged (see “Particle Handbook”, Asakura Shoten, p. 52, 1991)).
When the average secondary particle diameter of the amorphous silica is 3 μm or more, the ink absorption rate increases and the strength of the undercoat layer increases. If the average secondary particle diameter of the amorphous silica is 5 μm or less, the glossiness and ink absorbability when the ink receiving layer surface is cast finished will be sufficient.

In addition to the above-mentioned amorphous silica having an average secondary particle diameter of 3 to 5 μm, a commonly used known pigment can be used in the undercoat layer as long as the effects of the present invention are not impaired.
For example, kaolin, clay, calcined clay, zinc oxide, aluminum oxide, titanium oxide, aluminum hydroxide, calcium carbonate, 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, benzoguanamine plastic pigment, and the like. These pigments may be used alone or in combination of two or more.

〔adhesive〕
For the undercoat layer, a commonly used known adhesive can be used in combination.
For example, proteins such as casein, soybean protein, synthetic protein, various starches such as starch and oxidized starch, polyvinyl alcohols containing modified polyvinyl alcohol such as polyvinyl alcohol, cationic polyvinyl alcohol, silyl modified polyvinyl alcohol, carboxymethyl cellulose, Cellulose derivatives such as methyl cellulose, styrene-butadiene copolymer, conjugated diene polymer latex of methyl methacrylate-butadiene copolymer, acrylic polymer latex, vinyl polymer latex such as ethylene-vinyl acetate copolymer, aqueous Examples include polyurethane resins and aqueous polyester resins. These adhesives may be used alone or in combination of two or more.

  The adhesive for the undercoat layer is preferably 1 to 100 parts by weight with respect to 100 parts by weight of amorphous silica, because both the ink absorption and the effects of preventing paper dust generation are obtained. More preferably, it is -50 mass parts.

In addition to the components described above, various auxiliary agents such as dispersants, thickeners, antifoaming agents, antistatic agents, preservatives and the like that are used in general recording paper production can be appropriately added to the undercoat layer.
In addition, fluorescent dyes, colorants and the like can be added.

[Method for producing undercoat layer]
The dry coating amount of the undercoat layer is 7 to 9 g / m ² .
If the dry coating amount is 7 g / m ² or more, good ink absorbability is obtained, and if the dry coating amount is 9 g / m ² or less, sufficient print gloss is obtained.
The undercoat layer is produced by applying an undercoat layer coating solution comprising the above-described components onto a paper support and drying. The solid content concentration of the undercoat layer coating solution is preferably 5 to 50% by mass.
As a coating method for the coating solution for the undercoat layer, various known methods such as a blade coater, an air knife coater, a roll coater, a brush coater, a Chanplex coater, a bar coater, a lip coater, a gravure coater, a curtain coater, a slot die coater, a slide coater, etc. It is applied using a coating device.
Furthermore, a smoothing process such as super calendering or brushing can be performed as necessary.

<Ink receiving layer>
In the glossy ink jet recording paper of the present invention, an ink receiving layer is provided on the undercoat layer. The ink receiving layer comprises amorphous silica having an average secondary particle diameter of 90 to 700 nm and a degree of polymerization of 40.
It contains 00 to 7000 polyvinyl alcohol and a diallyldimethylammonium chloride-acrylamide copolymer having a mass average molecular weight of 150,000 to 300,000.
By providing this ink receiving layer, the glossy ink jet recording paper of the present invention has a higher printing density than the dye ink, and is excellent in water resistance of the ink.
For pigment ink, the printing density is high and the glossiness is high.

[Pigment]
Amorphous silica having an average secondary particle diameter of 90 to 700 nm is used for the ink receiving layer.
If the average secondary particle diameter of the amorphous silica is 90 nm or more, the ink absorbability is good, and if the average secondary particle diameter of the amorphous silica is 700 nm or less, the print density and surface glossiness are sufficient. Become.
As the amorphous silica, wet method silica, gas phase method silica and the like are preferably used.

  In addition to the above-mentioned amorphous silica having an average secondary particle diameter of 90 to 700 nm, the ink receiving layer is used in combination with commonly used known pigments such as alumina and colloidal silica as long as the effects of the present invention are not impaired. be able to. These pigments may be used alone or in combination of two or more.

〔adhesive〕
For the ink receiving layer, polyvinyl alcohol having a polymerization degree of 4000 to 7000 is used as an adhesive.
If the degree of polymerization is 4000 or more, the strength of the ink receiving layer is increased and cracking is suppressed, and a sufficient print density can be obtained in a pigment printer. When the degree of polymerization is 7000 or less, sufficient ink absorbability can be obtained, and the handling surface in the preparation of the coating liquid can be improved.

In addition to the above-mentioned polyvinyl alcohol having a polymerization degree of 4000 to 7000, a commonly used known adhesive can be used in the ink-receiving layer as long as the effects of the present invention are not impaired.
For example, polyvinyl alcohol, cation-modified polyvinyl alcohol, silyl-modified polyvinyl alcohol, polyvinyl acetal, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, casein, soy protein, synthetic proteins, starch, polypropylene oxide, polyethylene glycol, polyvinyl ether, polyvinyl having different degrees of polymerization Examples include acrylamide, polyvinyl pyrrolidone, styrene-butadiene copolymer, methyl methacrylate, and styrene-vinyl acetate copolymer. These adhesives may be used alone or in combination of two or more.

[Fixing agent]
A diallyldimethylammonium chloride-acrylamide copolymer having a mass average molecular weight of 150,000 to 300,000 is added as a fixing agent to the ink receiving layer.
Here, the mass average molecular weight is a value measured by gel permeation chromatography in terms of polystyrene.
If the mass average molecular weight is 150,000 or more, cracking is suppressed and sufficient pigment ink suitability is obtained. In addition, the water resistance when dye ink is used is good. If the mass average molecular weight is 300,000 or less, the viscosity will not be too high, so that a copolymer can be obtained stably and the handling surface in the preparation of the coating liquid will be good.
In addition, a simple diallyldimethylammonium chloride polymer decreases the printing density with a dye ink and deteriorates the water resistance. In the present invention, it is effective by being a copolymer with acrylamide.

In addition to the diallyldimethylammonium chloride-acrylamide copolymer having a mass average molecular weight of 150,000 to 300,000, the ink receiving layer is used in combination with a commonly used known fixing agent within a range not impairing the effects of the present invention. can do.
For example, polyalkylene polyamines such as polyethylene polyamine and polypropylene polyamine or derivatives thereof, acrylic polymers having secondary or tertiary amino groups and quaternary ammonium groups, or copolymers of these acrylamides, polyvinylamine and polyvinyl Amidines, dicyan-based cationic compounds represented by dicyandiamide / formalin copolymer, polyamine-based cationic compounds represented by dicyandiamide / polyethyleneamine copolymer, epichlorohydrin / dimethylamine copolymer, diallyldimethylammonium-SO ₂ polycondensate, diallylamine salt -SO ₂ double condensates, diallyl dimethyl ammonium chloride polymers, copolymers of allylamine salts, dialkyl aminoethyl (meth) acrylate 4 Kyushiotomo polymer Acrylamide diallylamine copolymer, a cationic resin having a 5-membered ring amidine structures, dimethylaminopropyl acrylamide polymers, and the like. These fixing agents may be used alone or in combination of two or more.

  Polyvinyl alcohol having a polymerization degree of 4000 to 7000 in the ink receiving layer is 10 to 20 parts by mass with respect to 100 parts by mass of amorphous silica from the viewpoint of maintaining a balance between ink absorbability, coating film strength and crack suppression. Preferably, the amount is 12 to 16 parts by mass, and more preferably 14 to 15 parts by mass.

  In addition, in order to obtain good color developability and storage stability of a dye ink, the diallyldimethylammonium chloride-acrylamide copolymer having a mass average molecular weight of 150,000 to 300,000 is based on 100 parts by mass of amorphous silica. It is preferably 8 to 12 parts by mass, and more preferably 9 to 11 parts by mass.

  In addition to the above-mentioned components, the ink receiving layer includes a dispersant, a crosslinking agent, a thickener, an antifoaming agent, an antistatic agent, an antiseptic, an ultraviolet absorber, and a storage stability improving agent used in general recording paper production. Various additives such as a fluorescent brightening agent and a coloring agent can be appropriately added.

[Method for producing ink receiving layer]
The dry coating amount of the ink receiving layer is 10 to 20 g / m ² , and preferably 12 to 15 g / m ² .
When the dry coating amount is 10 g / m ² or more, excellent gloss and ink absorbability are obtained, and when the dry coating amount is 20 g / m ² or less, cracking of the coating layer is suppressed. Good dot roundness can be obtained, and the printing density of pigment ink and dye ink is sufficient.
The ink receiving layer is prepared by applying an ink receiving layer coating liquid comprising the above-described components onto the undercoat layer. The solid content concentration of the ink receiving layer coating liquid is preferably 5 to 50% by mass, and more preferably 5 to 20% by mass. When the solid content concentration is 5% by mass or more, the drying efficiency of the ink receiving layer is improved. Moreover, if it is 50 mass% or less, the crack of a coating layer will be prevented.
Coating methods for the ink receiving layer coating liquid include blade coaters, air knife coaters, roll coaters, brush coaters, Champlex coaters, bar coaters, lip coaters, gravure coaters, curtain coaters, slot die coaters, slide coaters, sprays, etc. The coating is performed using various publicly known coating apparatuses.

In order to prevent the ink receiving layer from cracking, a crosslinking agent is preferably used.
The cross-linking agent may be added to the ink-receiving layer coating solution, may be previously applied on the undercoat layer before coating the ink-receiving layer, or may be applied after coating the ink-receiving layer. I do not care.
As the crosslinking agent, various known gelling agents that gel the adhesive can be used in addition to the known crosslinking agent having crosslinkability to the adhesive.
For example, as a compound having a crosslinking property to polyvinyl alcohol, an aldehyde crosslinking agent such as glyoxal, an epoxy crosslinking agent such as ethylene glycol diglycidyl ether, a vinyl crosslinking agent such as bisvinylsulfonylmethyl ether, boric acid and borax And boron-containing 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.

Here, 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, potassium and ammonium salts thereof. Among these, orthoboric acid and disodium tetraborate are preferably used because they have an effect of increasing the viscosity of the coating solution to an appropriate degree.
The compounding amount of the boron-containing compound depends on the kind of the boron-containing compound and the degree of polymerization of the polyvinyl alcohol, and is 0.01 to 2.0 g / m ² on either side of the undercoat layer or the ink receiving layer. Is preferred.
If the compounding quantity of a boron containing compound is 0.01 g / m < ² > or more, crosslinkability with a hydrophilic adhesive agent and gelatinization of a coating liquid will become favorable, and the crack of a coating layer will be suppressed. If the compounding quantity of a boron containing compound is 2.0 g / m < ² > or less, the height of a crosslinking density with a hydrophilic adhesive agent is enough, and a coating layer will become a thing which is hard to crack.

[Cast finish]
The surface of the ink receiving layer in the present invention is cast-finished. Thereby, it becomes the thing excellent in glossiness.
Here, the finish of the ink receiving layer surface is to transfer the smooth drum surface to the surface of the ink receiving layer by press-contacting the cast drum while the ink receiving layer coating solution is in a wet state. Say. Specifically, after applying the ink receiving layer coating liquid, a method in which the ink receiving layer coating liquid is pressed against the cast drum without passing through the drying process, and after casting the ink receiving layer coating liquid, it is cast in a semi-dry state. The method of press-contacting the drum, the method of applying a wetting liquid in a semi-dry state after applying a coating liquid for the ink-receiving layer and press-contacting to the cast drum, after coating the ink-receiving layer coating liquid For example, a method of press-contacting the cast drum after drying and applying a wetting liquid may be used.

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, and various starches such as starch and oxidized starch , Cellulose derivatives such as polyvinyl alcohol, carboxymethyl cellulose and methyl cellulose, 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, lithium Calcium sulfate, 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 acids and organic acids such as sodium, sodium dioctylsulfosuccinate and sodium aluminate, and amines such as methylamine, diethanolamine, diethylenetriamine, diisopropylamine, triethanolamine, ethanolamine and ethanolamine, Phosphate ester, polyoxyethylene alkylphenol ether phosphate ester salt, polyoxyethylene ether phosphate ester salt, Phosphate esters such as alkylphenol ether phosphates, polyoxyethylene, alkyl ethers, polyoxyethylene and aqueous ammonia, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, polyethylene glycol diglycyl ether, polypropylene glycol diglycidyl ether And various additives such as polyfunctional epoxy compounds such as diglycidyl adipate, urea-formaldehyde, polyamide-epichlorohydrin, glyoxal, and other water-resistant agents and printing suitability improvers. .
Various additives are added to the wetting liquid in an amount of 0.05 to 10% by mass, preferably 0.1 to 5% by mass.
Furthermore, various auxiliary agents such as a dispersant, an antifoaming agent, a colorant, a fluorescent dye, an antistatic agent, and an antiseptic can be added as appropriate to the wetting liquid.
Further, pigments such as alumina, colloidal silica, fine silica, clay and calcium carbonate can be added as an auxiliary agent.

When the ink receiving layer surface is cast-finished, a release agent is preferably used in order to smoothly peel the ink receiving layer from the cast drum.
The release agent is preferably used by any one of a method of adding to the ink receiving layer coating solution, a method of applying to the cast drum surface, and a method of adding to the wetting solution.
Examples of mold release agents include 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, calcium stearate, zinc stearate, potassium oleate, and ammonium oleate. Examples include higher fatty acid alkali salts, silicone compounds such as lecithin, silicone oil and silicone wax, and fluorine compounds such as polytetrafluoroethylene. Among these, a cationic release agent is particularly preferably used.

  Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples. Further, “parts” and “%” are solid contents excluding water unless otherwise specified, and indicate mass parts and mass%, respectively.

The outline of the manufacturing method of each ink jet recording paper is as follows.
First, a paper support was prepared. Next, an undercoat layer coating solution was prepared and applied on a paper support to prepare an undercoat layer. Thereafter, an aqueous borax solution and a separately prepared coating solution for an ink receiving layer were sequentially applied onto the undercoat layer, and cast finishing was performed to obtain an ink jet recording sheet.
The average secondary particle diameter was measured by preparing 200 g of a 3% silica aqueous dispersion, followed by stirring and dispersing with a high-speed collision type homogenizer at 1000 rpm for 30 minutes, and immediately observing with an electron microscope (SEM and TEM). Went.

Example 1
<Preparation of paper support>
Wood pulp (LBKP: freeness 440 ml CSF) 100 parts, filler (calcium carbonate 3: talc 1 ratio) 15 parts, commercially available sizing agent (trade name: Fibran 81K, manufactured by NSC Japan) 0.05 part , Using a papermaking material consisting of 0.45 parts of sulfuric acid band, 0.45 parts of starch, 0.4 parts of polyamide / epichlorohydrin resin (paper strength enhancer) and a little yield improver, and basis weight on a long net paper machine After obtaining a paper substrate of 188 g / m ^2, a supercalender treatment was performed at a linear pressure of 150 kg / cm to produce a paper support. The obtained paper support had a thickness of 210 μm and an air permeability of 30 seconds.

<Preparation of undercoat layer>
The following undercoat layer coating solution was applied onto the paper support with an air knife coater and dried so that the dry coating amount was 8 g / m ² , thereby preparing an undercoat layer.
(Preparation of coating solution for undercoat layer)
100 parts of synthetic amorphous silica (trade name: Fine Seal X-45, manufactured by Tokuyama Corporation, average secondary particle size 4.5 μm), 70 parts of silyl-modified polyvinyl alcohol (trade name: R1130, manufactured by Kuraray Co., Ltd.), fluorescent dye (Product name: Whitetex BPS (H), manufactured by Sumitomo Chemical Co., Ltd.) 2 parts, 5 parts of a cationic compound composed of diallyldimethylammonium chloride polymer (Product name: Unisense CP-102, manufactured by Senka Co., Ltd., ink fixing agent) were mixed. An undercoat layer coating solution having a solid content of 15% was prepared.

<Preparation of ink receiving layer>
A 3% by weight borax aqueous solution is applied onto the undercoat layer so that the dry coating amount is 1.5 g / m ² , without drying, and then 14 g / m ² in absolute dry weight. The following ink receiving layer coating solution was applied with a die coater, pressed onto a mirror drum having a surface temperature of 100 ° C., dried and finished to obtain a glossy ink jet recording paper.
[Preparation of ink receiving layer coating solution]
Using commercially available gas phase silica (trade name: Leolosil QS-30, manufactured by Tokuyama Corporation, average primary particle size 9 nm, specific surface area 300 m ² / g), repeated crushing and dispersion with a high-speed collision type homogenizer, and after classification, A 10% silica dispersion having an average secondary particle size of 200 nm was prepared.
To 100 parts of the dispersion (in solid content), diallyldimethylammonium chloride-acrylamide copolymer (trade name: PAS-J-81, manufactured by Nitto Boseki Co., Ltd., molecular weight 200,000, ink fixing agent), 10 parts, polyvinyl alcohol ( Product name: PVA145, manufactured by Kuraray Co., Ltd., 15 parts of polymerization degree 4500) and 1 part of a release agent (polyethylene wax, nonionic) were mixed to prepare a coating solution for an ink receiving layer.

(Example 2)
Except for replacing 15 parts of polyvinyl alcohol (PVA145, manufactured by Kuraray Co., Ltd., polymerization degree 4500) with 15 parts of polyvinyl alcohol (PVA140, manufactured by Kuraray Co., Ltd., polymerization degree 4000) of the ink receiving layer coating liquid of Example 1. In the same manner as in Example 1, a glossy ink jet recording paper was obtained.

(Example 3)
A glossy ink jet recording paper was prepared in the same manner as in Example 1 except that the blending part of polyvinyl alcohol (PVA145, manufactured by Kuraray Co., Ltd., polymerization degree 4500) in Example 1 was 25 parts. Obtained.

Example 4
A glossy ink jet recording paper was prepared in the same manner as in Example 1 except that the blending part of polyvinyl alcohol (PVA145, manufactured by Kuraray Co., Ltd., polymerization degree 4500) in Example 1 was changed to 8 parts. Obtained.

(Example 5)
For coating amount of the ink receiving layer coating solution of Example 1, except that the 14 g / m ² and 18 g / m ² in absolute dry mass, to obtain a glossy ink jet recording sheet in the same manner as in Example 1.

(Example 6)
Glossy inkjet recording paper as in Example 1 except that the molecular weight of the diallyldimethylammonium chloride-acrylamide copolymer, which is the ink fixing agent of the ink receiving layer coating liquid of Example 1, was changed to a molecular weight of 240,000. Got.

(Example 7)
A glossy ink jet recording paper was obtained in the same manner as in Example 1 except that the average secondary particle diameter of 200 nm of the 10% silica dispersion of the ink receiving layer coating liquid of Example 1 was changed to an average secondary particle diameter of 500 nm. .

(Example 8)
The paper support and the undercoat layer were the same as in Example 1, and the ink receiving layer was prepared as follows.
<Preparation of ink receiving layer>
A 3% by weight borax aqueous solution is applied onto the undercoat layer so that the dry coating amount is 1.5 g / m ² , without drying, and then 14 g / m ² in absolute dry weight. After applying the following ink receiving layer coating liquid with a die coater and drying with a dryer, apply the following wetting liquid, and immediately press and dry on a mirror drum having a surface temperature of 100 ° C. Got.
[Preparation of ink receiving layer coating solution]
Using commercially available gas phase silica (trade name: Leolosil QS-30, manufactured by Tokuyama Corporation, average primary particle size 9 nm, specific surface area 300 m ² / g), repeated crushing and dispersion with a high-speed collision type homogenizer, and after classification, A 10% silica dispersion having an average secondary particle size of 200 nm was prepared.
To 100 parts of the dispersion (in solid content), diallyldimethylammonium chloride-acrylamide copolymer (trade name: PAS-J-81, manufactured by Nitto Boseki Co., Ltd., molecular weight 200,000, ink fixing agent), 10 parts, polyvinyl alcohol ( (Product name: PVA145, manufactured by Kuraray Co., Ltd., polymerization degree 4500) 15 parts were mixed to prepare an ink-receiving layer coating solution.
(Preparation of wetting liquid)
100 parts of water, 5 parts of colloidal silica, and 1 part of a release agent (polyethylene wax, nonionic) were mixed to prepare a wetting liquid.

(Comparative Example 1)
About preparation of the coating liquid for undercoat layers of Example 1, it replaced with synthetic amorphous silica (Brand name: Fine seal X-45, the Tokuyama company make, an average secondary particle diameter of 4.5 micrometers), and synthetic amorphous A glossy ink jet recording paper was obtained in the same manner as in Example 1 except that silica (trade name: Tokuyama Fine Seal T-32, manufactured by Tokuyama Corporation, average secondary particle size: 1.5 μm) was used.

(Comparative Example 2)
About preparation of the coating liquid for undercoat layers of Example 1, it replaced with synthetic amorphous silica (Brand name: Fine seal X-45, the Tokuyama company make, an average secondary particle diameter of 4.5 micrometers), and synthetic amorphous A glossy ink jet recording paper was obtained in the same manner as in Example 1 except that silica (trade name: Thyroid ED-5, manufactured by Grace Devison, average secondary particle size 8.0 μm) was used.

(Comparative Example 3)
For the preparation of the undercoat layer of Example 1, an ink jet recording paper was obtained in the same manner as in Example 1 except that the coating amount was 6 g / m ² by dry weight.

(Comparative Example 4)
For the preparation of the undercoat layer of Example 1, an ink jet recording paper was obtained in the same manner as in Example 1 except that the coating amount was 10 g / m ² by dry weight.

(Comparative Example 5)
Regarding the preparation of the ink receiving layer coating liquid of Example 1, an ink jet recording paper was obtained in the same manner as in Example 1 except that the following silica dispersion was used.
(Preparation of silica dispersion)
Using commercially available gas phase silica (trade name: Leolosil QS-30, manufactured by Tokuyama Corporation, average primary particle size 9 nm, specific surface area 300 m ² / g), repeated crushing and dispersion with a high-speed collision type homogenizer, and after classification, A 10% silica dispersion having an average secondary particle size of 80 nm was prepared.

(Comparative Example 6)
Regarding the preparation of the ink receiving layer coating liquid of Example 1, an ink jet recording paper was obtained in the same manner as in Example 1 except that the following silica dispersion was used.
(Preparation of silica dispersion)
Using commercially available gas phase method silica (trade name: Leolosil QS-30, manufactured by Tokuyama Corporation, average primary particle size 9 nm, specific surface area 300 m ² / g), it is crushed with a sand mill, and after classification, the average secondary particle size is 900 nm. A 10% silica dispersion was prepared.

(Comparative Example 7)
About preparation of the coating liquid for ink receptive layers of Example 1, it replaced with polyvinyl alcohol (PVA145, the Kuraray company make, polymerization degree 4500), except having used polyvinyl alcohol (PVA135, the Kuraray company make, polymerization degree 3500). In the same manner as in Example 1, an ink jet recording paper was obtained.

(Comparative Example 8)
For the preparation of the ink receiving layer coating liquid of Example 1, diallyldimethylammonium chloride-acrylamide copolymer (trade name: PAS-J-81L, manufactured by Nitto Boseki Co., Ltd., molecular weight 100,000, ink fixing agent) was used. Except for the above, an ink jet recording paper was obtained in the same manner as in Example 1.

(Comparative Example 9)
The preparation of the ink receiving layer coating solution of Example 1 was performed in the same manner as in Example 1 except that a diallyldimethylammonium chloride polymer (trade name: Unisense CP-102, manufactured by Senka Co., Ltd., ink fixing agent) was used. Inkjet recording paper was obtained.

(Comparative Example 10)
The preparation of the ink receiving layer coating solution of Example 1 was the same as Example 1 except that an acrylamide-diallylamine copolymer (trade name: Sumirez Resin 1001, manufactured by Sumitomo Chemical Co., Ltd., ink fixing agent) was used. Inkjet recording paper was obtained.

(Comparative Example 11)
For the preparation of the ink receiving layer of Example 1, an ink jet recording paper was obtained in the same manner as in Example 1 except that the dry coating amount of the ink receiving layer was 8 g / m ² .

(Comparative Example 12)
For the production of the ink receiving layer of Example 1, an ink jet recording paper was obtained in the same manner as in Example 1 except that the dry coating amount of the ink receiving layer was 25 g / m ² .

(Evaluation method and evaluation criteria)
About the inkjet recording paper obtained by the said Example and the comparative example, the printability and glossiness in inkjet recording were evaluated with the following method. The results are shown in Table 1.

[Printability in inkjet recording]
The evaluation of printability was evaluated by using each type of printer of dye ink and pigment ink according to each item of print density, ink absorbency, and glossiness of the printed portion.

Evaluation printer printer A: Commercially available dye ink type ink jet printer (trade name: PM-G800, manufactured by Seiko Epson Corporation)
Printer B: Commercially available dye ink type ink jet printer (trade name: PM-V600, manufactured by Seiko Epson Corporation)

Printing density Black solid printing was performed using printer A (dye ink type) and printer B (pigment ink type), and the printing density was measured with a Macbeth reflection densitometer (Macbeth RD-914).

・ Ink absorbability Using printer B (pigment ink type), black, cyan, magenta, yellow, red, green, and blue solid colors are printed in a grid pattern so as to touch each other. The ink bleeding at the boundary between them was visually evaluated according to the following criteria.
(Double-circle): The blur of printing is not recognized at all and it is an excellent level.
○: Slight bleeding is observed, but there is no practical problem.
○-: Slightly inferior to ○, but practically no problem.
Δ: Slightly blurring of printing and slightly problematic in practical use.
X: The level at which printing blur is remarkable and becomes a serious problem in practical use.

・ Glossiness of printed part Using a printer B (pigment ink type), a photographic image (JIS X 9204 compliant "High-definition color digital standard image (XYZ / SCID) data"), image identification code: N1, image name: Glass and female) were printed, and the uniformity of the printed part was visually evaluated according to the following criteria.
A: Excellent level with no unevenness in printed gloss on the entire image.
○: A level where the glossiness of printing is slightly lowered in a portion having a dark printing color development property, but does not cause a problem as a whole.
×: Level at which printing gloss partially disappears and becomes a serious problem in practical use.
In addition, in the evaluation of ◎, the most excellent one was designated as ◎ +.

[Glossiness]
Glossiness was evaluated by visually observing glossiness and smoothness from the lateral direction with respect to the surface of the blank recording paper according to the following criteria.
A: Extremely high gloss.
○: Glossy.
X: The glossiness is inferior.

Claims (2)

A glossy inkjet recording paper having an undercoat layer and an ink-receiving layer whose surface is cast-finished on a paper support, the undercoat layer comprising amorphous silica having an average secondary particle diameter of 3 to 5 μm and an adhesive containing the door, and dry coating weight of the layer of 7~9g / ^{m 2,} the ink-receiving layer, the average secondary particle size of 90~700nm amorphous silica, polymerization degree of 4,000 to 7,000 A gloss comprising polyvinyl alcohol and a diallyldimethylammonium chloride-acrylamide copolymer having a weight average molecular weight of 150,000 to 300,000 and a dry coating weight of 10 to 20 g / m ^2. Inkjet recording paper.   The glossy inkjet recording paper according to claim 1, wherein the content of polyvinyl alcohol in the ink receiving layer is 10 to 20 parts by mass with respect to 100 parts by mass of amorphous silica.