JP2003145916A - Ink jet recording paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording paper, which is excellent in the ink jet recordability such as especially a printing density, a printing water resistance, an ink absorptivity and luster and has a high luster on the ink jet recording paper. SOLUTION: In the ink jet recording paper, in which a priming coating layer including a pigment, a cationic compound and an adhesive is provided on one side of a base material and a cast layer including the adhesive, the pigment and a releasant is provided on the priming coating layer, among the cationic compound, the compound having the weight average molecular weight of 100,000 or more occupies 50 to 90 mass % of its total mass and, at the same time, the compound having the weight average molecular weight of 10,000 to 50,000 occupies 10 to 50 mass % of its total mass.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording paper, and more particularly to an ink jet recording paper having excellent ink jet recording suitability such as print density, print water resistance and ink absorbency and having high gloss.

[0002]

2. Description of the Related Art Recording by an inkjet printer is
It is used in various fields due to its low noise, high-speed recording, and easy multicoloring. As the ink jet recording paper, high-quality paper designed so as to have high ink absorbability, coated paper having a surface coated with a porous pigment, and the like are applied. By the way, all of these inkjet recording papers are mainly so-called matte inkjet recording papers having low surface gloss, and there is a demand for inkjet recording papers having high surface gloss and excellent appearance.

In recent years, in particular, the technology of ink jet printers has advanced and high quality recording comparable to silver halide photography has become possible, and there is an increasing demand for photographic paper-like recording media corresponding thereto.

Generally, as a paper having a high surface gloss, a coated paper having a high gloss coated with a plate-like pigment on the surface and optionally a super calender treatment, or a wet coating layer is used. A so-called cast coated paper is known, which is obtained by copying the mirror surface by pressing and drying it on a heating drum surface having a mirror surface.

The cast coated paper has high surface gloss and superior surface smoothness as compared with ordinary super calendered coated papers, and thus has an excellent printing effect. However, it is used exclusively for high-quality printed matter and the like, but when used for inkjet recording paper, it has various difficulties.

Generally, in the conventional cast coated paper, as disclosed in, for example, US Pat. No. 5,275,846, the film-forming substance such as an adhesive in the pigment composition constituting the cast layer is a mirror surface drum of a cast coater. High gloss is obtained by copying the surface. However, the presence of this film-forming substance causes the coating layer to lose its porosity, resulting in a problem that the ink absorbency during inkjet recording is extremely reduced. In order to improve the ink absorbability, it is important to make the cast layer porous so as to easily absorb the ink. For that purpose, it is necessary to reduce the film forming property. Reducing the amount results in lower white paper gloss. As described above, it was extremely difficult to satisfy both the surface gloss of the cast coated paper and the suitability for inkjet recording at the same time.

As a method for solving the above problem, a monomer having an ethylenically unsaturated bond is polymerized on a base paper provided with a recording layer containing a pigment and an adhesive as main components.
A coating liquid containing a copolymer composition having a glass transition point of 0 ° C. or higher as a main component is applied to form a cast layer,
The present inventors have found that an ink jet recording paper having excellent gloss and ink absorbability can be obtained by pressing the cast layer to a mirror surface drum heated while in a wet state and finishing by drying. JP-A-7-89
No. 220 publication.

By the way, in recent years, applications such as high-speed and full-color ink jet recording have been expanded, and high definition of recorded images, high gloss and high image quality, and high recording density are demanded. Gloss and recording quality comparable to those of photographic printing paper are required. In order to meet such demands, photo ink or the like has been adopted, and it is difficult to achieve it even with the previously proposed technique as the amount of ink increases. JP-A-59-33176 proposes to incorporate a water-soluble polyamine sulfone as a cationic compound into a recording layer to improve the coloring property and water resistance of a recorded matter, and also has a molecular weight of 1,000 to 400. , 00
0 is said to be suitable. JP-A-7-1
Japanese Patent No. 49038 discloses the use of a dicyandiamide polyalkylene polyamine copolymer as a cationic compound. JP 10-86505 A discloses a cation having a molecular weight of 2,000 to 50,000 obtained by reacting a polyol having a molecular weight of 300 to 5,000, a diol having a molecular weight of less than 300, a triol, a diamine and a triamine with an isocyanate. There is disclosed a method in which a recording layer is blended with a hydrophilic polyurethane resin to obtain good recording color tone and water resistance. However, in recent inkjet printers equipped with 6 or 7 color inks so as to print an image comparable to a high-definition photograph, the ink amount tends to increase as compared with the conventional one. . When printed with such a printer, the weight average molecular weight is 5
The amount of less than 10,000 cationic compounds has a problem that after printing, water adheres to the printed part to cause bleeding (hereinafter referred to as print water resistance).
Tends to get worse. In the printed portion with a large amount of ink, the cationic compound is easily eluted by water, and the printing water resistance is poor.

In Japanese Unexamined Patent Publication No. 10-81065, an ink jet is provided in which at least one undercoat layer containing a pigment and an adhesive is provided on a paper substrate, and a cast layer containing a polymer resin is further provided on the undercoat layer. In a recording paper, a paper base material is proposed in which the paper base material is coated or impregnated with a cationic compound at least on the side where the undercoat layer is provided. In some examples, two kinds of cationic compounds are selected, but the weight average molecular weight and the printing water resistance are not described, and if the weight average molecular weight of the cationic compound is not properly selected, high definition is obtained. Print water resistance of the part with a large amount of ink (printed part such as mixed color black with cyan ink, magenta ink and yellow ink) printed with an inkjet printer equipped with 6 color inks so that an image comparable to a photograph can be printed The sex was insufficient.

In Japanese Patent Laid-Open No. 2000-238419,
An inkjet recording paper having at least two coating layers provided on a substrate, wherein a polymer emulsion having an average particle diameter of 0.02 to 0.15 μm is present in at least the surface layer of the coating layers. Average particle size is 0.01 to 0.15 μm
An inkjet recording paper characterized by containing the colloidal silica of In some examples, two kinds of cationic compounds are selected, but the weight average molecular weight and the printing water resistance are not described, and if the weight average molecular weight of the cationic compound is not properly selected, high definition is obtained. Print water resistance of the part with a large amount of ink (printed part such as mixed color black with cyan ink, magenta ink and yellow ink) printed with an inkjet printer equipped with 6 color inks so that an image comparable to a photograph can be printed The sex was insufficient.

[0011]

The present invention relates to an ink jet recording paper, and more particularly to an ink jet recording paper having excellent ink jet recording suitability such as print density, print water resistance and ink absorbency and having high gloss.

[0012]

The present inventor adopts the following configuration in order to solve the above problems. That is, the present invention provides [1] a base material and an undercoat layer containing a pigment, a cationic compound and an adhesive on one surface thereof, and the adhesive, the pigment and a release agent on the undercoat layer. In the inkjet recording paper provided with a cast layer, among the cationic compounds, those having a weight average molecular weight of 100,000 or more are 50 to 90% by mass, and those having a weight average molecular weight of 10,000 to 50,000 are 10 to 50% by mass. %, An inkjet recording paper.

The present invention includes the following aspects. [2] The cationic compound is at least one cationic compound selected from the group consisting of diallyldimethylammonium salt polycondensates, acrylamide-diallylamine polycondensates and dicyandiamide-polyethyleneamine polycondensates [1]. The inkjet recording paper described. [3] The inkjet recording paper according to [2], wherein the cationic compound is a polycondensation product of diallyldimethylammonium salt. [4] The inkjet recording paper according to any one of [1] to [3], wherein the pigment of the cast layer is colloidal silica. [5] The inkjet recording paper according to any one of [1] to [4], wherein the adhesive of the cast layer is a styrene / acrylic copolymer emulsion. [6] 75 ° surface gloss (JIS-P-8142)
50% or more, The inkjet recording paper according to any one of [1] to [5]. [7] 75 ° surface gloss (JIS-P-8142)
65% or more, The inkjet recording paper as described in [6].

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors provide an ink jet recording in which a base material and an undercoat layer containing a pigment, a cationic compound and an adhesive are provided on one surface thereof, and a cast layer is provided on the undercoat layer. In the paper, 50 to 50 of the above-mentioned cationic compounds have a weight average molecular weight of 100,000 or more.
90 mass% and weight average molecular weight of 10,000 to 50,000 is 1
It has been found that when the content is 0 to 50% by mass, an inkjet recording paper having excellent inkjet recording suitability such as print density, print water resistance and ink absorbency, and high gloss can be obtained. That is, it is effective to mix a cationic compound in the undercoat layer in order to improve the recording density of the ink to be inkjet-recorded, the printing water resistance and the ink absorbency, and particularly, the weight average of the cationic compound. By specifying the molecular weight, the effect of improving the printing water resistance is very large.

(Substrate) The substrate used in the present invention is not particularly limited, and a paper substrate such as acid paper or neutral paper used for general coated paper, or a gas-permeable substrate. The resin film sheet which it has can be used.

The paper base material is mainly composed of wood pulp and optionally a pigment. As the wood pulp, various chemical pulps, mechanical pulps, recycled pulps, etc. can be used,
The beating degree of these pulps can be adjusted by a beating machine in order to adjust paper strength, papermaking suitability and the like. The beating degree (freeness) of the pulp is not particularly limited, but generally 250 to 5
It is about 50 ml (CSF: JIS-P-8121). Chlorine-free pulp such as so-called ECF and TCF pulp can also be preferably used. If necessary, the pigment may be blended for the purpose of imparting opacity or adjusting the ink absorbability, and calcium carbonate, calcined kaolin, silica, titanium oxide or the like may be used. In this case, the compounding amount is 1
The amount is preferably about 20 to 20% by mass, and if it is more than 20% by mass, the paper strength may decrease. As an auxiliary agent, a sizing agent, a fixing agent, a paper strengthening agent, a cationizing agent, a yield improving agent, a dye,
A fluorescent whitening agent or the like can be added. Further, in the size press step of a paper machine, starch, polyvinyl alcohol, a cationic compound or the like can be applied and impregnated to adjust the surface strength, the Steckigt sizing degree and the like. In particular, in order to obtain high glossiness, it is preferable to size-press the cationic compound. Steckigt sizing degree is 1-2
About 100 seconds is preferable. If the Steckigt sizing degree is lower than 1 second, wrinkles may be generated during coating, which may cause operational problems. Or curling or cockling after printing may be remarkable. The basis weight of the base material is not particularly limited, but is about ²⁰ to 400 g / m ² .

(Undercoat layer) In the present invention, an undercoat layer containing a pigment, a cationic compound and an adhesive is provided on the substrate. When the weight average molecular weight of the cationic compound contained in the undercoat layer is generally tens of thousands or less,
It is easily dissolved in water, and the printing water resistance of the printed portion with a large amount of ink such as mixed color black is poor. Further, a cationic compound having a weight average molecular weight of generally 100,000 or more is difficult to be eluted in water,
For example, since it impedes the permeation of the ink like polyvinyl alcohol and the like, there is a risk that the ink absorbability will decrease.
When the weight average molecular weight of the cationic compound is 100,000 or more,
The print density of colors such as cyan, magenta, and yellow increases, and when the weight average molecular weight is 50,000 or less, the print density of black tends to increase.

Further, the low molecular weight cationic compound may be excessively eluted into the cast layer paint when the cast layer paint comes into contact with the undercoat layer, and the cast paint may be shocked and gelled. On the other hand, in the case of a high molecular weight cationic compound, it is difficult for the cast layer coating material in contact with the undercoat layer to agglomerate, and it takes time for the gloss to appear, so it takes time for the operation to stabilize, and In that case, the yield may be deteriorated or the gloss may be insufficient. However, when a high molecular weight cationic compound is used, the printing density is higher than when a low molecular weight cationic compound is used, and moreover, it is less likely to be eluted into water, so that the printing water resistance is improved. From the above, by controlling the weight average molecular weight of the cationic compound to be added to the undercoat layer, it is particularly excellent in inkjet recording suitability and gloss such as printing density, printing water resistance and ink absorption, and a mirror surface during cast coating. The inventors have found that an excellent effect that the drum has no cloudiness and has a high gloss and a good yield at the time of production is obtained, and thus the present invention has been completed.

Examples of the cationic compound for the undercoat layer used in the present invention include 1) polyalkylene polyamines such as polyethylene polyamine and polypropylene polyamine or derivatives thereof, 2) secondary amine groups, tertiary amine groups and secondary amine groups. Acrylic polymer having quaternary ammonium group, 3) Polyvinylamine and polyvinylamidines, 4) Dicyan-based cationic compound represented by dicyandiamide-formalin polycondensate, 5) Representative by dicyandiamide-polyethyleneamine polycondensate Polyamine-based cationic compound, 6) epichlorohydrin-dimethylamine addition polycondensate, 7) diallyldimethylammonium-S0 ₂ polycondensate, 8) diallylamine salt-S
0 _double condensate, 9) diallyldimethyl ammonium salt polycondensate, 10) diallyldimethylammonium - acrylamide polycondensate, 11) polycondensate of allylamine salt,
12) Dialkylaminoethyl (meth) acrylate 4
Examples thereof include cationic compounds such as graded salt polycondensates and 13) acrylamide-diallylamine polycondensates, which can be used alone or in combination.

Among the above-mentioned cationic compounds, diallyldimethylammonium salt polycondensates, acrylamide-diallylamine polycondensates and dicyandiamide-polyethyleneamine polycondensates are suitable for ink jet recording such as print density, print water resistance and ink absorbency. It is excellent in gloss and is preferably used. The diallyldimethylammonium salt polycondensate is particularly preferably used because a particularly high printing density can be obtained.

The molecular weight of the cationic compound has a great influence on the gloss and the operability of the ink jet recording paper. The cationic compound having a weight average molecular weight of 100,000 or more is
Since the cast layer coating composition that is in contact with the undercoat layer is unlikely to aggregate, if the proportion in the cationic compound exceeds 90% by mass, it takes time for the gloss to appear, resulting in poor yield during production. Or, uneven gloss and pinholes are likely to occur, resulting in insufficient gloss. Therefore, the proportion in the cationic compound is preferably 90% by mass or less. Further, a cationic compound having a weight average molecular weight of 50,000 or less is excessively eluted in the cast layer coating material to cause shock in the cast layer coating material, and thus the cast layer coating material is apt to gel. The ratio in the volatile compound is preferably 50% by mass or less. That is, since the cationic compound having a small weight average molecular weight is easily eluted into the coating material for the cast layer,
To achieve both gloss development and stability of cast paint,
It is preferable to adjust the amount of the cationic compound added to the undercoat layer to a specific range. The cationic compound having a weight average molecular weight of 100,000 or more is 50 to 90% by mass,
Further, those having a weight average molecular weight of 10,000 to 50,000 are preferably 10 to 50% by mass.

The cationic compound in the undercoat layer is pigment 1
It can be used in an amount of 1 to 100 parts by mass, more preferably 5 to 50 parts by mass, relative to 00 parts by mass. If the blending amount is less than 1 part by mass, it is difficult to obtain the effect of improving the printing density and the printing water resistance. If the blending amount is more than 100 parts by mass, on the contrary, the printing density may decrease or image blurring may occur.

The pigment in the undercoat layer may be kaolin, clay,
Calcined clay, amorphous silica (also called amorphous silica),
Zinc oxide, aluminum 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,
Various publicly known pigments in the general coated paper manufacturing field such as benzoguanamine-based plastic pigments can be used alone or in combination. Among these, it is preferable to use amorphous silica, alumina, and zeolite having high ink absorbability as the main components.

Examples of the adhesive for the undercoat layer include proteins such as casein, soybean protein, and synthetic protein, various starches such as starch and oxidized starch, polyvinyl alcohols such as polyvinyl alcohol, cationic polyvinyl alcohol, and silyl-modified polyvinyl alcohol. , Cellulose derivatives such as carboxymethyl cellulose and methyl cellulose, styrene-butadiene copolymers, conjugated diene-based polymer latexes of methyl methacrylate-butadiene copolymers, acrylic polymer latexes, vinyl-based polymers such as ethylene-vinyl acetate copolymers. Conventionally known adhesives which are generally used for coated paper such as combined latex are used alone or in combination. Among them, polyvinyl alcohols such as polyvinyl alcohol, cationic polyvinyl alcohol, and silyl-modified polyvinyl alcohol are preferably used because they improve the surface strength of the undercoat layer.

The mixing ratio of the pigment and the adhesive in the undercoat layer depends on the kind, but is generally 1 to 100 parts by weight, preferably 2 to 50 parts by weight, based on 100 parts by weight of the pigment. Adjusted.

In addition, various auxiliary agents such as a dispersant, a thickener, a defoaming agent, an antistatic agent, a preservative, a fluorescent dye, a colorant, etc., which are used in the production of general coated paper, are appropriately contained in the undercoat layer. Is added.

The undercoat layer coating material composed of the above-mentioned materials is generally adjusted to have a solid content concentration of about 5 to 50% by mass, and has a dry mass of ² to 100 g / m ² , preferably 5 to 5% on a paper substrate. About 50 g / m ² , more preferably 5 to 20 g
/ M ² to be applied. If the coating amount is less than 2 g / m ² , the ink absorbency may be poor, and blurring of the recorded image may be caused, or the gloss after coating the cast layer may be lowered. Further, in the case of a paper base material, the amount of ink absorbed by the paper base material is large, so the paper after recording may be wavy (cockling), or sputtered by the printer (paper holding roll or gear after recording). Pressed marks (spur marks) may be noticeable. When the coating amount is more than 100 g / m ² , the ink easily penetrates and is distributed not only on the cast layer side but also on the substrate side, so that the print density may decrease. In addition, the strength of the undercoat layer may decrease, and powder may fall off or the surface may be easily scratched.

The undercoat layer coating material is applied by various publicly known coating devices 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 and a curtain coater. To be dried. Further, if necessary, smoothing treatment such as super calendering and brushing can be performed after the recording layer is dried.

(Cast Layer) The cast layer of the present invention comprises an adhesive, a pigment and a release agent. The adhesive in the cast layer, for example, polyvinyl alcohol, cation-modified polyvinyl alcohol, polyvinyl alcohol such as silyl-modified polyvinyl alcohol, casein, soybean protein, synthetic proteins, starch, cellulose derivatives such as carboxymethyl cellulose and methyl cellulose, vinyl acetate. -Based polymer emulsion, styrene-butadiene copolymer emulsion, ethylene-vinyl acetate copolymer emulsion, acrylic copolymer emulsion, styrene-acrylic copolymer emulsion, water-based acrylic resin, water-based polyurethane resin and water-based polyester resin, etc. In addition, various conventionally known adhesives generally used in the coated paper field can be used alone or in combination.

Among the above emulsions, a styrene / acrylic copolymer emulsion is preferable from the viewpoints of sharpness and gloss of recorded images.

The weight average molecular weight of the copolymer used as the adhesive in the cast layer is preferably 10 to 10,000,000, more preferably 5,000 to 5,000,000. If the molecular weight is lower than 1000, the strength of the coating film tends to be insufficient, and if the molecular weight is higher than 10 million, the stability of the emulsion tends to be insufficient.

The average particle size of the emulsion is 0.0
The range of 2 to 0.15 μm is preferable. If the average particle size of the emulsion is less than 0.02 μm, the ink absorbency is reduced, while if it exceeds 0.15 μm, the surface gloss and the sharpness of color development of the recorded image are reduced.

The glass transition temperature of the copolymer is 50 to 50.
Copolymers in the range of 150 ° C are preferred. If the glass transition point of the copolymer is lower than 50 ° C., the film formation of the cast layer will proceed excessively during drying, and the porosity of the surface will decrease, which may reduce the ink absorption rate. On the other hand, when the glass transition point of the copolymer is higher than 150 ° C., the film may not be sufficiently formed during drying and the gloss may be insufficient.

The pigment in the cast layer is, for example, kaolin, clay, calcined clay, amorphous silica (also referred to as amorphous silica), zinc oxide, aluminum 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, etc. Various pigments publicly known and used in the general coated paper manufacturing field can be used alone or in combination.

Among these, it is preferable to use amorphous silica, alumina, colloidal silica and zeolite, which have high ink absorbency, as the main components. More preferably,
Colloidal silica, more preferably anionic colloidal silica.

The average particle size of the anionic colloidal silica is 0.01 to 0.15 μm, preferably
0.015 to 0.12 μm, and more preferably
It is 0.02 to 0.10 μm. Average particle size is 0.0
If it is less than 1 μm, the ink absorbency is lowered, and
When it exceeds 0.15 μm, the gloss and the sharpness of color development of the recorded image are deteriorated.

The composition ratio (solid content mass ratio) of the adhesive and the pigment of the cast layer is preferably in the range of 60/40 to 3/97, more preferably in the range of 50/50 to 5/95. And more preferably 40/60 to 7/93
Is the range. When the ratio of the adhesive exceeds 60% by mass,
The clearness of color development of the recorded image tends to decrease, and if it is less than 3% by mass, the gloss tends to decrease.

The release agent used in the cast layer is
A release agent used in the production of ordinary coated paper for printing or cast paper for printing can be used. Specifically, polyethylene wax, polyolefin waxes such as polypropylene wax, calcium stearate, zinc stearate, potassium oleate, higher fatty acid alkali salts such as ammonium oleate, stearic acid, higher fatty acids such as oleic acid, lecithin, Examples thereof include silicone compounds such as silicone oil and silicone wax, fluorine compounds such as polytetrafluoroethylene, and higher fatty acid amides.

The above-mentioned coating material for cast layer contains pigments, defoaming agents, colorants, which are used in general printing coated paper and ink jet recording paper in order to adjust whiteness, viscosity, fluidity and the like. Various auxiliaries such as a fluorescent whitening agent, an antistatic agent, a preservative, a dispersant, and a thickener are appropriately added. It is also possible to add a cationic compound to impart ink dye fixability.

In the present invention, the casting method is used as the method for providing the cast layer. The coating layer is dried on a mirror-finished drum with smoothness (mirror-finished metal, plastic, glass, etc. drums), mirror-finished metal plate, plastic sheet, film, glass plate, etc. to coat the smooth surface. This is a method of obtaining a smooth and glossy coating layer surface by copying on the layer. As a method for providing a coating layer by a casting method, the coating liquid for the coating layer is coated on a substrate or an undercoat layer, and the coating layer is heated to a mirror surface while the coating layer is in a wet state. Examples of the method include a method of press-contacting with a drum and finishing by drying (wet casting method), or a method of press-contacting with a heated mirror-finished drum after drying once and then rewetting, and finishing by drying (rewet casting method). Further, a method (precast method) in which the coating liquid is directly applied to the heated mirror-finished drum, and then pressed onto the undercoat layer surface of the base material or the base material provided with the undercoat layer and then dried (precast method) can be employed.

The preferred temperature range of the heated mirror drum is 50 to 150 ° C, more preferably 70 to 120 ° C.
Is.

When applying the coating liquid for the cast layer, various known coating devices such as a blade coater, an air knife coater, a roll coater, a brush coater, a chanplex coater, a bar coater and a gravure coater can be used. In addition, after applying the coating liquid for the cast layer, while the cast layer is in a wet state as described above (wet casting method), or after drying and rewetting once (rewet casting method), the heated mirror surface drum is applied. It is pressed and dried to form a cast layer.

The coating amount of the cast layer is preferably 1 to 30 g / m ² in dry mass, more preferably ^{2 to 20} g / m ² .
m ² , more preferably 3 to 15 g / m ² . If it is less than 1 g / m ² , the print density and gloss may not be sufficient, and if it is more than 30 g / m ² , the quality improvement effect is saturated and drying is burdened and the operability may be deteriorated. There is.

After the cast layer is provided, a smoothing treatment can be further performed by a super calender or the like, if necessary.

7 of the recording surface of the ink jet recording paper
The 5 ° surface glossiness (JIS-Z-8741) is preferably 50% or more, more preferably 65% or more in order to obtain excellent image quality and photographic-quality high-quality recording.

[0046]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In addition, parts and% in the examples are parts by mass and% by mass, respectively, unless otherwise specified.

[Paper substrate A] 100 parts of wood pulp (LBKP; freeness of 500 ml CSF), 10 parts of calcined kaolin (trade name: Ansilex), commercial sizing agent 0.05
Parts, 1.5 parts of sulfuric acid band, 0.5 parts of wet paper strength agent, 0.75 parts of starch are used to produce a paper base material A having a basis weight of 120 g / m ^{2 with} a Fourdrinier paper machine. did. The Stoeckigt sizing degree of this paper substrate A was 10 seconds.

[Paper Substrate B] Further, a cationic compound (manufactured by Nichika Kagaku Co., Ltd., trade name: Neofix E) is added to the paper substrate A.
-117, dicyandiamide resin) 5% liquid 40 mL
/ M ² size and then dried to obtain a paper base material B.

Example 1 On a paper base material A, the following coating liquid for undercoat layer was applied in a dry mass of 1
It was coated with an air knife coater so as to be ² g / m ² and dried. Next, the following cast layer coating liquid, on the above-mentioned undercoat layer, after coating using a roll coater,
Immediately, it was pressed against a mirror-finished drum having a surface temperature of 90 ° C., dried, and then released to obtain an inkjet recording paper. The coating amount of the cast layer at this time was 7 g / m ² in dry mass.

[Coating liquid for undercoat layer] (solid concentration 17
%) Synthetic amorphous silica (manufactured by Tokuyama Corporation, trade name: Fineseal X-60, average secondary particle diameter 6.0 μm, primary particle diameter 15 nm) 80 parts, zeolite (manufactured by Tosoh Corporation, trade name: Toyo Builder, 20 parts of average particle diameter 1.5 μm, silyl-modified polyvinyl alcohol (Kuraray Co., Ltd., trade name:
R-1130) 20 parts, polydiallyldimethylammonium chloride salt polycondensate (manufactured by Senka Co., trade name: Unisense CP-104, weight average molecular weight 200,000) 15 parts,
Polydiallyldimethylammonium chloride salt polycondensate (manufactured by Senka Co., trade name: Unisense CP-101, weight average molecular weight 20,000) 5 parts, fluorescent dye (Sumitomo Chemical Co., Ltd., W
hitex BPSH) 2 parts.

[Cast layer coating liquid] (solid content concentration 30
%) 80 parts of anionic colloidal silica and 20 parts of styrene-acrylic copolymer emulsion (Lion Co., trade name: Elsard 740), 2 parts of lecithin as a release agent.

Example 2 In the coating liquid for undercoat layer of Example 1, Unisense CP was used.
-104 Ink jet in the same manner as in Example 1 except that 15 parts of polydiallyldimethylammonium chloride salt polycondensate (manufactured by Senka Co., trade name: Unisense CP-105, weight average molecular weight 500,000) was used instead of 15 parts. I got a recording sheet.

Example 3 In the coating liquid for undercoat layer of Example 1, Unisense CP was used.
15 parts of -104 dicyandiamide-diethyleneamine polycondensate (manufactured by Nitto Boseki, trade name: PAS-J-4
1. Ink jet recording paper was obtained in the same manner as in Example 1, except that the amount of the polymer was changed to 1, 15 parts by weight average molecular weight of 150,000).

Example 4 In the coating liquid for undercoat layer of Example 1, Unisense CP
-104 15 parts to 10 parts, Unisense CP-101
An inkjet recording paper was obtained in the same manner as in Example 1 except that 5 parts was replaced with 10 parts.

Example 5 In the coating liquid for undercoat layer of Example 1, Unisense CP
InkJet recording as in Example 1 except that 5 parts of -101 5 parts of polydiallyldimethylammonium chloride salt polycondensate (manufactured by Senka Co., trade name: Unisense CP-102, weight average molecular weight of 50,000) were replaced. I got the paper.

Example 6 An ink jet recording paper was obtained in the same manner as in Example 1 except that the paper base material A was changed to the paper base material B.

Comparative Example 1 In the coating liquid for undercoat layer of Example 1, Unisense CP was used.
-104 15 parts and Unisense CP-101 5 parts were replaced with Unisense CP-104 20 parts,
An ink jet recording sheet was obtained in the same manner as in Example 1.

Comparative Example 2 In the coating liquid for undercoat layer of Example 1, Unisense CP was used.
-104 15 parts and Unisense CP-101 5 parts were replaced with Unisense CP-101 20 parts,
An ink jet recording sheet was obtained in the same manner as in Example 1.

Comparative Example 3 In the coating liquid for undercoat layer of Example 1, Unisense CP was used.
15 parts of -104 and 5 parts of Unisense CP-101 were mixed with polydiallyldimethylammonium chloride salt polycondensate (manufactured by Senka Co., trade name: Unisense CP-10).
2. Ink jet recording paper was obtained in the same manner as in Example 1 except that 20 parts of the weight average molecular weight of 50,000) was used.

Comparative Example 4 In the coating liquid for undercoat layer of Example 1, Unisense CP was used.
InkJet recording in the same manner as in Example 1 except that 5 parts of polydiallyldimethylammonium chloride salt polycondensate (manufactured by Senka Co., trade name: Unisense CP-103, weight average molecular weight 100,000) was used instead of 5 parts of -101. I got the paper.

Comparative Example 5 In the coating liquid for undercoat layer of Example 1, Unisense CP was used.
An inkjet recording paper was obtained in the same manner as in Example 1 except that 15 parts of -104 and 5 parts of Unisense CP-101 were removed.

Print density, print water resistance, ink absorbency of the 11 types of ink jet recording paper obtained above, 75
The surface gloss and drum stain resistance were evaluated. The results are shown in Table 1. The above evaluation was carried out by the following method.

[Inkjet recording] Black, magenta, yellow, and mixed color black (80% black) are recorded by using an inkjet printer (manufactured by Canon Inc., trade name: BJ F850).
Printing and high-definition color digital standard image data
ISO / JIS-SCID sample N3 (image name: fruit basket: manufactured by Japanese Standards Association) was printed.

[Printing Density] The printing density of solid printed portions of black, magenta and yellow was measured with RD-914 (manufactured by Macbeth Co.).

[Printing Water Resistance] Printed high-definition color digital standard image data ISO / JIS-SCID sample N3 (image name fruit basket: manufactured by Japan Standards Association)
After one side was wetted with water and naturally dried, the blurring of the image was visually evaluated. A: There is no bleeding at all. ◯: There is some blurring, but there is no problem in practical use. ×: Slightly bleeding, practically problematic.

[Ink Absorption] The ink absorption was visually evaluated from the boundary of the printed portion of the mixed color black (80% black). ◯: The boundary is clear and there is no blurring. X: The boundary is not clear and there is bleeding.

[75 degree surface gloss] JIS-P-814
According to 2, the 75 degree gloss of the white paper part was measured.

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[Table 1]

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As is clear from Table 1, the ink jet recording paper obtained by the present invention is an ink jet recording paper excellent in ink jet recording suitability such as print density, print water resistance and ink absorbency and gloss. , Very practical.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasutaka Kogata             Made by Oji 1-10-6 Shinonome, Koto-ku, Tokyo             Paper Co., Ltd. Shinonome Research Center F-term (reference) 2C056 EA05 EA13 FC06                 2H086 BA16 BA31 BA33 BA34 BA41

Claims (5)

[Claims] 1. A base material, an undercoat layer containing a pigment, a cationic compound and an adhesive on one surface thereof, and a cast layer containing the adhesive, pigment and a release agent on the undercoat layer. In the ink jet recording paper, among the cationic compounds, those having a weight average molecular weight of 100,000 or more are 50 to 90% by mass, and a weight average molecular weight of 10,000 to
Ink jet recording paper, characterized in that the content of 50,000 is 10 to 50% by mass. 2. The cationic compound is at least one cationic compound selected from the group consisting of diallyldimethylammonium salt polycondensates, acrylamide-diallylamine polycondensates and dicyandiamide-polyethyleneamine polycondensates. 1. The inkjet recording paper according to 1. 3. The ink jet recording paper according to claim 1, wherein the pigment of the cast layer is colloidal silica. 4. The ink jet recording paper according to claim 1, wherein the adhesive of the cast layer is a styrene / acrylic copolymer emulsion. 5. A 75 ° surface glossiness (JIS-P-814
2) is 50% or more.
4. The inkjet recording paper according to any one of 4.