JP2005220480A - Method for producing information recording paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information recording paper keeping bulkiness in the case of using a bulky paper as the base paper and having light weight and good recording properties. <P>SOLUTION: The information recording paper is produced by applying one or more coating layers by a curtain coating method to the surface of a low-density base paper containing an organic compound effective for inhibiting the cohesion between the fibers of pulp. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an information recording sheet used for various information recording.

  Various information recording papers have been developed corresponding to various information recording methods. For example, ink jet recording paper, thermal recording paper, LBP recording paper, form paper, and the like are known. This information recording paper is configured by applying a recording layer corresponding to a recording method on a base paper.

  Among these, the ink jet recording method ejects ink droplets from a nozzle toward a recording sheet at high speed, and includes a large amount of solvent in the ink. Therefore, the recording paper is required to have a property of quickly absorbing ink. Also. With the recent spread of computers and digital cameras, ink-jet images are required to have a quality close to that of a silver salt photograph, and it is necessary to improve glossiness, color developability, resolution and color reproducibility.

  The thermal recording system is a system in which a coloring layer previously provided on a recording paper is developed by applying heat, and is widely applied to various measuring instruments, printing apparatuses, facsimiles, and the like. With the increase in the speed of thermal recording, recording paper is required to obtain a clear color image at a high density even with minute energy and to have excellent storage stability such as heat resistance, water resistance, oil resistance and plasticizer resistance. Has been.

By the way, the request | requirement of transportation and a mail cost, and also the weight reduction of printed matter has increased in recent years, and the bulky paper (low density paper) is examined in order to satisfy | fill this request | requirement. This bulky paper reduces the density while maintaining the thickness and strength of the paper in the same way as conventional paper. For example, the paper can be made with predetermined fine fibers (see, for example, Patent Document 1), and chemicals can be added during paper making. It can be manufactured by adding and weakening the binding of pulp fibers (for example, see Patent Documents 2 and 3). And the information recording paper which used the said bulky paper as the base paper and apply | coated the recording layer on the surface is disclosed (refer the said patent documents 1-3).
When a coating layer is provided on a bulky base paper, there is a problem that the coating solution easily penetrates into the gap, and the bulk is greatly reduced accordingly. In particular, blade coaters and gate roll coaters press the coating solution toward the substrate side to adjust the coating amount, which not only promotes penetration of the coating solution into the bulky base paper, but also makes the bulky base paper thinner by pressurization. There is also a problem. Further, in the manufacturing process, an extra coating solution is required in anticipation of the penetration of the coating solution, and there is a problem that the productivity is lowered and the cost is increased.
In order to provide a recording layer or the like on a bulky base paper, a curtain coating method can be considered. In the curtain coating method, the curtain film is freely dropped on the base paper. In order to stably form the curtain film, the coating liquid usually contains a surfactant. However, when curtain coating is applied to the above-described bulky base paper, the coating solution penetrates into the gaps of the bulky base paper, and accordingly, the paper thickness is reduced and the bulk is reduced, and it is not lighter than the specified paper thickness. There is a problem that the recording quality (printing quality) deteriorates. This problem becomes prominent when the coating liquid contains a surfactant.
JP-A-10-219588 JP 2002-103791 A JP 2002-293023 A

  Accordingly, the present invention provides an information recording paper that is light while maintaining bulkiness, has good recording characteristics, and is excellent in productivity and cost when curtain coating is performed using a bulky base paper as a base paper. An object is to provide a manufacturing method.

  As a result of intensive studies on the above problems, the present inventors solved the above problems by using a low-density base paper, which is a bulky base paper containing an organic compound that inhibits interfiber bonding of pulp, and curtain coating a coating solution on the base paper. It has been found that it can be done, and has reached the present invention.

The information recording paper manufacturing method of the present invention is characterized in that one or more coating liquids are applied by a curtain method to the surface of a low-density base paper containing an organic compound that inhibits interfiber bonding of pulp. When the organic compound is blended in an amount of 0.3 parts by weight based on 100 parts by weight of the dry weight of the pulp, the tensile strength of the low-density base paper according to JIS-P8113 is determined using the pulp. It is preferable that it is 5-30% lower than the tensile strength in the paper not blended. The coating solution preferably contains 0.2 to 2.0 parts by weight of a surfactant with respect to 100 parts by weight of the pigment. The density of the information recording paper is preferably 1.20 g / cm ³ or less, more preferably 1.15 or less to 0.70 or more. Density is low, the effect as bulky paper exceeds 1.20 g / cm ^3, also there is a possibility that is less than 0.7 g / cm ³ sheet strength is reduced.
It is preferable that an angle formed between the liquid film falling during curtain coating of the coating liquid and the low-density base paper is 25 to 110 °. The surface tension of the coating solution is preferably 45 mN / m or less, and the B-type viscosity is preferably 50 to 2000 mPa · s. Or it is preferable that the Zahn cup viscosity of the said coating liquid is 10 to 300 second, and the ductility at the time of this viscosity measurement is 15 cm or more.

  According to the present invention, when curtain coating is performed using a bulky base paper (low density base paper) as a base paper, it is lightweight while maintaining bulkiness, good recording characteristics, and excellent productivity and cost. Information recording paper is obtained.

  Hereinafter, embodiments of the present invention will be described. The information recording paper of the present invention uses a bulky base paper (low density base paper) as a support and is provided with a coating layer (which may include a recording layer) on at least one surface thereof.

The low-density base paper is manufactured by making a paper material containing pulp and an organic compound that inhibits interfiber bonding of the pulp. When curtain coating is performed on this bulky base paper, the penetration of the coating liquid into the voids of the bulky base paper can be suppressed, the bulkiness can be maintained and the weight can be reduced, and the recording suitability is also improved. In particular, this effect becomes remarkable when the coating solution contains a surfactant. In particular, when the compounding amount of the surfactant is 0.2 to 2.0 parts by weight with respect to 100 parts by weight of the pigment, the above effect is increased. The fiber of mechanical pulp is more rigid than chemical pulp and effective in reducing the density, but blending of mechanical pulp into information recording paper has a problem in quality. Waste paper pulp is generally pulped by mixing fine paper, newsprint, magazines, coated paper, etc., and has a higher density and lower density than virgin (unused paper pulp). There is a limit to conversion.

  Any organic compound may be used as long as it inhibits the interfiber bonding of the pulp. The following test can be used as a method for determining whether or not an organic compound has such characteristics. First, 0.3 part by weight of the organic compound to be tested is blended with 100 parts by weight of the absolutely dry pulp of the pulp composition to prepare a pulp slurry. Using this slurry, paper was made with a laboratory orientation tester (manufactured by Kumagai Riki Co., Ltd.) at a rotation speed of 900 rpm, pressed in accordance with JIS-8209, dried at 50 ° C. for 1 hour with a blow dryer, and then tested. Get. When the density of the test paper thus obtained is lower than the density of the paper not containing the organic compound, the organic compound can be used in the present invention, but the density reduction amount is preferably 5 to 5%. An organic compound that is about 30%, more preferably 5 to 15%, is preferably used. If the amount of density reduction is less than 5%, the effect of density reduction is small, and if it exceeds 30%, paper strength may be reduced.

  The organic compound is preferably blended in an amount of 0.2 parts by weight or more based on 100 parts by weight of the dry weight of the pulp. If the blending amount is less than 0.2 parts by weight, the bulky effect is insufficient. The compounding amount of the organic compound can be appropriately changed depending on the purpose of use of the information recording paper of the present invention, but if the compounding amount is increased too much, the strength of the obtained paper may be lowered. For example, in order to maintain strength, the organic compound is preferably blended in an amount of 3.0 parts by weight or less, more preferably 1.5 parts by weight or less.

  Specific examples of the organic compound include oil-based nonionic surfactants, sugar alcohol-based nonionic surfactants, sugar-based nonionic surfactants, and polyhydric alcohol-type nonionic surfactants. Or classified, higher alcohol, higher alcohol or higher fatty acid ethylene oxide or propylene oxide adduct, polyhydric alcohol and fatty acid ester compound, polyhydric alcohol and fatty acid ester compound ethylene oxide adduct, fatty acid diamidoamine , Fatty acid monoamides, fatty acid polyamidoamines, aliphatic quaternary ammonium salts, and the like. More preferred are polyhydric alcohol and fatty acid ester compounds, fatty acid diamidoamines, fatty acid monoamides, and the like.

  In the base paper of the present invention, normal pulp, filler and the like are blended in addition to the organic compound. In the present invention, the type of pulp blended into the base paper is not particularly limited. For example, hardwood kraft pulp (hereinafter referred to as LBKP), softwood kraft pulp (hereinafter referred to as NBKP), thermomechanical pulp, groundwood pulp, waste paper pulp and the like are used. It is preferable to use kraft pulp from the viewpoint of improving printability. In addition to pulp and organic compounds, fillers may be blended. As fillers, known as heavy calcium carbonate, light calcium carbonate, kaolin, clay, talc, hydrated silicic acid, white carbon, titanium oxide, synthetic resin filler, etc. Fillers are listed. The blending amount of the filler is preferably 6% by weight or more per pulp weight. Further, if necessary, a sulfuric acid band, a sizing agent, a paper strength enhancer, a yield improver, a coloring pigment, a dye, an antifoaming agent, and the like may be blended. Further, in addition to the organic compound, amorphous silica, amorphous silicate, etc., which are bulky fillers, can be combined and blended.

  Furthermore, a surface treatment agent containing a water-soluble polymer as a main component may be applied to the surface of the base paper after paper making for the purpose of improving surface strength and size. As the water-soluble polymer, those usually used as a surface treating agent such as oxidized starch, hydroxyethyl etherified starch, enzyme-modified starch, polyacrylamide, polyvinyl alcohol and the like can be used alone or in combination. In addition to the water-soluble polymer, a paper strength enhancer for the purpose of water resistance and surface strength improvement and an external sizing agent for the purpose of imparting sizing can be added to the surface treatment agent.

The paper making method of the base paper is not particularly limited, and the paper making may be performed by any of acid paper making, neutral paper making, and alkaline paper making using a long net machine including a top wire, a round net machine, or the like. The basis weight of the base paper is preferably 30 to 200 g / m ² .

(Curtain application)
Next, curtain coating performed on the base paper will be described. The curtain coating method is a method in which a liquid is allowed to flow down and freely drop and applied to a substrate in a non-contact manner. Compared with other coating methods (for example, blade method), the curtain coating method does not apply pressure to the bulky base paper during coating, and can prevent the coating liquid from penetrating into the bulky base paper. On the other hand, the blade method, for example, presses the coating liquid toward the substrate side to adjust the coating amount, but causes a problem that the coating liquid easily penetrates into the bulky base paper due to the pressing.

  In the present invention, using the above bulky base paper (support), by applying the curtain method to prevent the coating liquid from penetrating into the bulky base paper, the coating liquid is more retained on the surface of the base paper, The bulkiness of the base paper layer and the coating layer can be maintained. On the other hand, in the blade method or the like, the coating liquid easily penetrates into the bulky base paper by pressing, and the thickness of the base paper or the coating layer becomes thin and the bulkiness cannot be maintained. Further, since the curtain method forms a coating layer having a contour along the surface irregularities of the base paper, the coverage of the base paper is improved, the recording suitability is good, and the strength is maintained even at a low coating amount.

  As the curtain coating method, known methods such as a slide curtain method, a slit curtain method, a slot curtain method and the like can be adopted, and there is no particular limitation, but a multilayer slide curtain coating method capable of simultaneous multilayer coating is preferable. In the multi-layer slide curtain coating method, a multi-layer coating layer is applied simultaneously. In this method, an inclined slide curtain die is formed after a plurality of coating liquids for forming each coating layer are accumulated in separate areas on the upper side of the slide curtain through different flow paths that lead from the bottom to the top. When the liquid flows down, the coating liquids are combined in layers and fall onto the substrate in this state. The required coating thickness can be controlled by the pump flow rate, and is particularly suitable for ink jet recording paper because ink jet suitability is improved.

(Coating layer)
The coating layer formed by curtain coating may be a recording layer for recording information, or may be various underlayers (such as an undercoat layer) or an overcoat layer (such as a topcoat layer). Further, a plurality of these layers may be included. In order to prevent the above-described coating liquid from penetrating into the bulky base paper, it is preferable to curtain-coat at least the lowermost coating layer. In this way, even if the upper layer is formed by a method other than curtain coating, the penetration of the liquid into the bulky base paper can be suppressed at the lowermost layer. Of course, it is more preferable to apply curtain coating to all the coating layers because the bulkiness and productivity are improved.

  The recording layer is, for example, an ink receiving layer in the case of inkjet recording paper, and a thermal coloring layer (or in addition to this, an over layer, an intermediate layer, or an under layer) in the case of thermal recording paper. The recording layer contains, for example, a pigment, a binder (adhesive), a predetermined additive, and the like. Examples of additives include sizing agents, antifoaming agents, tint modifiers, coloring dyes, coloring pigments, fluorescent dyes, UV absorbers, antioxidants, preservatives, water resistance agents, surfactants, and increased wet paper strength. Agents can be used.

(Coating solution)
The coating solution used for curtain coating is a recording layer, a base layer, or an overcoat layer as the coating layer. This coating solution contains a surfactant in order to stabilize the curtain film without causing bubbles or the like, film formation defects, or the like during curtain coating. Surfactants include anionic surfactants such as carboxylates, sulfonates, sulfates and phosphates, and nonionic surfactants such as ether, ether ester, ester and nitrogen-containing surfactants. , Amphoteric surfactants such as betaine, aminocarboxylate and imidazoline derivatives. In the present invention, a nonionic surfactant is preferred from the viewpoint of bulkiness and film stability. As described above, since the curtain coating method contains a surfactant in the coating solution, the coating solution is more likely to penetrate into the bulky base paper than the coating solution used in other coating methods, and the bulk is reduced accordingly. There is a tendency that the weight cannot be reduced with respect to the prescribed paper thickness.
For this reason, it is preferable to define the amount of surfactant contained in the coating solution. Specifically, the coating liquid preferably contains 0.2 to 2.0 parts by weight of a surfactant with respect to 100 parts by weight of the pigment. When the content of the surfactant is less than 0.2 parts by weight, the above-described curtain film stabilizing effect is not sufficient. On the other hand, when the content exceeds 2.0 parts by weight, the coating liquid easily penetrates into the bulky base paper, and the bulkiness tends to be lowered. More preferably, it is 0.3-0.8 weight part. The above pigments are synthetic amorphous silica, colloidal silica, colloidal alumina, pseudoboehmite, aluminum hydroxide, alumina, lithopone, hydrohalosite, magnesium carbonate, magnesium hydroxide, aluminum silicate, diatomaceous earth, calcium silicate, silicic acid. Magnesium, light calcium carbonate, heavy calcium carbonate, kaolin, clay, talc, titanium dioxide, zinc oxide, satin white and the like, and these pigments are used alone or in combination.

  In the present invention, it is useful to adjust the physical properties and coating conditions of the coating solution. For example, it is preferable to use those having the following surface tension, viscosity, and contact angle because various troubles during coating can be prevented and bulkiness, production stability, and coating quality can be improved.

  The surface tension of the coating solution is preferably 45 mN / m or less. If it exceeds 45 mN / m, the coating film (film in a free-falling state) at the time of curtain coating tends to sway and the film breaks in the width direction. From the viewpoint of a stable coating film, the surface tension is preferably 30 to 45 mN / m.

The B-type viscosity of the coating solution is preferably 50 to 2000 mPa · s, and more preferably 100 to 1000 mPa · s. When the B-type viscosity is less than 50 mPa · s, film breakage in the width direction during curtain coating tends to occur, and when it exceeds 2000 mPa · s, the ductility of the liquid decreases and coating unevenness occurs.
The Zahn cup viscosity of the coating solution is preferably 10 to 300 seconds, more preferably 30 to 200 seconds. When the Zahn cup viscosity is 10 seconds or less, film breakage and uneven coating in the width direction are likely to occur, and when 300 seconds are exceeded, uneven coating is likely to occur.

  The ductility at the time of measuring the Zahn cup viscosity of the coating solution is preferably 15 cm or more, more preferably 20 cm or more. If the ductility is less than 15 cm, the ductility of the coating solution decreases, the coating film becomes unstable, and coating unevenness and film breakage are likely to occur. The ductility at the time of measuring the Zaan cup viscosity indicates the length of the liquid until it breaks when the liquid falling from the prepared hole of the Zaan cup is cut by viscosity measurement.

  The contact angle of the coating liquid (the angle formed between the liquid film of the coating liquid falling during curtain coating and the bulky base paper (low density base paper)) is preferably 25 to 110 °, and more preferably 40 to 80 °. preferable. When the contact angle is less than 25 °, the coating liquid penetrates too much into the bulky base paper and loses bulkiness, and the printability deteriorates. If the contact angle exceeds 110 °, the adhesiveness of the coating layer to the bulky base paper deteriorates and it becomes impossible to apply the coating solution.

  Next, the case where the information recording paper of the present invention is applied to a thermal recording paper and an ink jet recording paper will be described.

(Thermal recording paper)
The thermal recording paper of this embodiment is provided with a thermal coloring layer as a recording layer. The thermosensitive coloring layer may be formed by a conventionally known method. Usually, a thermosensitive coloring layer coating solution containing an organic developer, a basic colorless dye, a binder, a pigment and other necessary additives is prepared, and this is applied to the bulk. It is formed by applying a curtain on a high-grade paper and then drying it.

  The organic developer is not particularly limited, and examples thereof include bisphenol A, 4-hydroxybenzoic acid esters, and 4-hydroxyphthalic acid diesters described in JP-A-3-207688 and JP-A-5-24366. Phthalic acid monoesters, bis- (hydroxyphenyl) sulfides, 4-hydroxyphenylaryl sulfones, 4-hydroxyphenylaryl sulfonates, 1,3-di [2- (hydroxyphenyl) -2-propyl] -Benzenes, 4-hydroxybenzoyloxybenzoic acid esters, bisphenol sulfones, aminobenzenesulfonamide derivatives described in JP-A-8-59603, diphenylsulfone bridged compounds described in WO97 / 16420, WO02 / No. 0812229 There are compounds of JP 2002-301873 JP are exemplified.

  The basic colorless dye is not particularly limited, and conventionally known dyes such as triphenylmethane, fluoran, azaphthalide, and fluorene can be used. These basic dyes can be used alone or in admixture of two or more.

  Examples of the binder include fully saponified polyvinyl alcohol having a polymerization degree of 200 to 1900, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, amide-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, butyral-modified polyvinyl alcohol, and the like. Cellulose derivatives such as ethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, acetyl cellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer, polyvinyl chloride, polyvinyl acetate, polyacrylamide, polyacrylic ester, polyvinyl butyral , Polystyrene and their copolymers, polyamide resin, silicone resin, petroleum resin, terpene resin Ketone resin, and coumarone resin. The above polymer compounds can be used by being dissolved in a solvent such as water, alcohol, ketone, ester or hydrocarbon, or can be used in a state of being emulsified or pasted in water or other media. These can be used in combination depending on the quality.

  A pigment may be added to the thermosensitive coloring layer. Examples of the pigment include silica, calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc, titanium oxide, zinc oxide, aluminum hydroxide, and other inorganic fillers, as well as polystyrene resins. And organic fillers such as urea-formalin resin, styrene-methacrylic acid copolymer, styrene-butadiene copolymer, and hollow plastic pigment.

  The thermosensitive coloring layer includes sensitizers, image stabilizers, release agents such as fatty acid metal salts, lubricants such as waxes, benzophenone and triazole UV absorbers, water-resistant agents such as glyoxal, dispersants, Foaming agents, antioxidants, fluorescent dyes and the like can be added.

  The compounding amount of the organic developer, basic dye, and other various components is not particularly limited, but usually 1 to 8 parts by weight of organic developer and 1 to 20 parts of filler with respect to 1 part by weight of the basic dye. It is appropriate to blend 10 parts by weight and 10 to 25% by weight of the total solid content of the binder.

  The above organic developer, basic dye, etc. are atomized to a particle size of several μm or less with a pulverizer such as a ball mill, attritor or sand grinder, or an appropriate emulsifier, and a binder is added to this, and further necessary Depending on the conditions, various additives are added to obtain a coating solution.

  An undercoat layer (underlayer) may be provided between the bulky base paper and the thermosensitive coloring layer. The undercoat layer usually contains a binder and a filler. As the binder and filler, those exemplified as the components of the thermosensitive coloring layer can be used. The coating solution for the undercoat layer may be prepared, for example, using water as a dispersion medium and adding a binder, a filler, and various additives as required. Further, a binder layer may be provided between the under layer and the thermosensitive coloring layer.

  Furthermore, for the purpose of improving the storage stability of the thermal recording paper, an overcoat layer containing a polymer compound or the like can be provided on the thermal coloring layer. This overcoat layer may be a glossy layer. An intermediate layer may be provided between the overcoat layer and the thermosensitive coloring layer.

It is also possible to adopt a layer configuration in which any one of the layers below the thermosensitive coloring layer described above and any of the layers above the thermosensitive coloring layer are appropriately combined. With respect to the coating amount of each layer coating solution, for example, the thermosensitive coloring layer can have a dry weight of about 1 to 12 g / m ² , preferably about ² to 10 g / m ^2, and can be an under layer, an intermediate layer or an overcoat layer. The coating amount can be adjusted in the range of about 0.1 to 15 g / m ² , preferably about 0.5 to 10 g / m ² in terms of dry weight.

(Inkjet recording paper)
The ink jet recording paper of this embodiment is provided with an ink receiving layer as a recording layer. The ink receiving layer preferably contains a pigment, a binder and a cationic chemical.

As pigments for the ink receiving layer, synthetic amorphous silica, colloidal silica, colloidal alumina, pseudoboehmite, aluminum hydroxide, alumina, lithopone, hydrohalosite, magnesium carbonate, magnesium hydroxide, aluminum silicate, diatomaceous earth, calcium silicate Coating pigments such as magnesium silicate, light calcium carbonate, heavy calcium carbonate, kaolin, clay, talc, titanium dioxide, zinc oxide, and satin white can be used alone or in combination.
When high gloss is imparted, it is preferable to use cationic colloidal silica. As the cationic colloidal silica, those having various shapes such as a spherical shape and a chain shape can be used. Particularly, a shape having a chain shape, that is, a shape in which a plurality of cationic spherical colloidal silica particles of primary particles are connected in series or partially branched. Is preferred. The average particle size of the primary particles of the cationic chain colloidal silica is preferably 3 to 40 nm. If the average particle size of the primary particles is less than 3 nm, it is difficult to produce stably, and if it exceeds 40 nm, the specific surface area of the cationic chain colloidal silica becomes small. Ink capturing ability of the ink becomes lower, and the color density and color reproducibility become insufficient. In particular, cationic colloidal silica is preferably blended in the pigment by 90% by weight or more.
3-6 are preferable and, as for the pH in the dispersion liquid of cationic colloidal silica, it is still more preferable that it is 4-6. If the pH is lower than 3, the reaction between the cationic colloidal silica and the anionic chemical causes the coating solution to thicken, resulting in embedding of bubbles, lowering the suitability for curtain coating, and foam-derived coating defects are likely to occur. Become. On the other hand, if the pH is higher than 6, the stability of the cationic colloidal silica is lost, and the preparation of the coating solution becomes difficult.

Examples of the binder used in the ink receiving layer include starches such as oxidized starch and esterified starch, cellulose derivatives such as carboxymethylcellulose and hydroxyethylcellulose, polyvinyl alcohol and derivatives thereof, polyvinylpyrrolidone, casein, gelatin, soy protein, Examples thereof include styrene-acrylic resins and derivatives thereof, styrene-butadiene latex, acrylic emulsion, vinyl acetate emulsion, vinyl chloride emulsion, urethane emulsion, alkyd emulsion, and derivatives thereof. The blending amount of the binder is preferably 30 parts by weight or less with respect to 100 parts by weight of the pigment, but is not particularly limited depending on the required coating layer strength. When using the above-mentioned cationic colloidal silica as a pigment, since it itself has a binding force, addition of a binder is not essential, but a binder may be added. As the binder, for example, water-soluble polymers such as polyvinyl alcohol, casein, starch, and gelatin, or water-dispersible polymers such as styrene-butadiene latex, acrylic latex, and vinyl acetate latex can be used. The blending amount of the binder is preferably 10 parts by weight or less, and more preferably 5 parts by weight or less with respect to 100 parts by weight of colloidal silica. When the blending amount exceeds 10 parts by weight, although the surface strength increases, the ink absorbency and glossiness decrease.
Next, a cationic chemical (cationic compound) will be described. Cationic chemicals are not particularly limited, and those generally known as dye fixing agents for ink jet recording paper can be used. For example, as a cationic chemical, a secondary amine, a tertiary amine, which forms an insoluble salt with a sulfonic acid group, a carboxyl group, an amino group or the like contained in a water-soluble direct dye or a water-soluble acid dye in an aqueous dye ink, Or what contains a quaternary ammonium salt is mentioned. A cationic chemical | medical agent can be used individually or in combination of 2 or more types. In particular, when colloidal silica is used, the amount of the cationic chemical compound is preferably 0.1 to 20 parts by weight, particularly preferably 1 to 10 parts by weight with respect to 100 parts by weight of colloidal silica. If the content of the cationic chemical is less than 0.1 parts by weight, the ink cannot be sufficiently fixed in the ink receiving layer. If the content exceeds 20 parts by weight, other problems such as yellowing of the paper derived from the cationic chemicals occur. Occurs.

  In order to further improve the ink absorbability of the ink receiving layer, it is preferable to provide an under layer as the second ink receiving layer between the ink receiving layer and the bulky base paper. Examples of the pigment used for the under layer include synthetic silica, alumina and alumina hydrate (alumina sol, colloidal alumina, pseudoboehmite, etc.), aluminum silicate, magnesium silicate, magnesium carbonate, light calcium carbonate, and heavy used for the ink receiving layer. In addition to inorganic pigments such as calcium carbonate, kaolin, talc, calcium sulfate, titanium dioxide, zinc oxide, zinc carbonate, calcium silicate, and aluminum hydroxide, organic pigments such as plastic pigments and urea resins can be used. Examples of the binder used for the under layer include those used for the ink receiving layer.

  For the coating layer (not limited to the ink receiving layer) in the ink jet recording paper of this embodiment, a pigment dispersant, a thickener, an antifoaming agent, an antifoaming agent, a release agent, a foaming agent, a coloring dye, and a coloring pigment , Fluorescent dyes, ultraviolet absorbers, antioxidants, preservatives, water resistance agents, surfactants, wet paper strength enhancers and the like can be appropriately contained within a range not impairing the effects of the present invention.

The coating amount of the ink receiving layer coating solution can be adjusted, for example, in the range of about ² to 25 g / m ² , preferably about 3 to 20 g / m ² in terms of dry weight. Further, an undercoat layer (under layer) may be provided between the bulky base paper and the ink receiving layer, and an overcoat layer (glossy layer) or the like may be provided on the ink receiving layer.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples. “Part” and “%” represent “part by weight” and “% by weight”, respectively, unless otherwise specified.

(Preparation of base paper)
<Base paper 1>
Hardwood bleached kraft pulp (LBKP, freezing degree CSF 320 ml), polyhydric alcohol and fatty acid ester compound (KB110, manufactured by Kao Corporation) as an organic compound that inhibits interfiber binding of pulp 0.8% by weight (vs. pulp) ) Calcium carbonate 17% by weight (per paper weight), 25% ash in paper as filler, Amorphous silicate (hydrous aluminum silicate, bulk specific gravity 0.25 g / ml) 8% (per paper weight) ), And 0.2% by weight of alkyl ketene dimer (based on the weight of paper) as a neutral sizing agent, to prepare a paper stock. This stock was made with a test paper machine at a speed of 50 m / min to obtain a low density paper with a paper thickness of 130 μm (basis weight 78 g / m ² ). Next, a surface treatment aqueous solution having a concentration of 7.5% consisting of 100 parts by weight of starch as a water-soluble polymer and 1 part by weight of a sizing agent was prepared, and this surface was applied to low-density paper using a two-roll size press The treatment aqueous solution was applied at a coating amount of 4 g / m ² to obtain a base paper.

<Base paper 2-11>
In place of the organic compound used in the base paper 1, another organic compound, trade name KB08W (manufactured by Kao), trade name Sursol VL (manufactured by BASF), trade name, high volume P liquid (manufactured by Bayer), trade name Base papers 2 to 5 were obtained in exactly the same manner as base paper 1 except that React Bake (manufactured by Sansho) was used.
Base papers 6 to 11 were obtained in the same manner as base paper 1 except that isopropyl alcohol, starch, casein, polyethylene glycol, oleic acid, and polyacrylamide were used in place of the organic compounds used in base paper 1. It was.
<Base paper 12 (blank)>
Base paper 12 was obtained in the same manner as base paper 1 except that the organic compound used in base paper 1 was not blended.

  About each obtained base paper, the tensile strength was measured according to JIS-P8113 and the decreasing rate of the tensile strength with respect to the blank (base paper 12) was calculated | required. The obtained results are shown in Table 1.

As is clear from Table 1, in the case of base papers 1 to 5 using various organic compounds, the reduction rate of the tensile strength exceeded 5%, and a sufficiently bulky base paper was obtained. On the other hand, in the case of base papers 6, 9, and 10, the rate of decrease in tensile strength was less than about 5%, and the bulkiness was insufficient. In the case of the base papers 7, 8, and 11, the tensile strength was improved from that of the blank, and a bulky base paper was not obtained. From the above results, the base paper 1 was used in the following examples.
[Example 1]

(Manufacture of thermal recording paper)
1. Coating solution for undercoat layer Coating solution A: 100 parts of calcined kaolin, 11 parts of styrene-butadiene copolymer latex (solid content 48%), 10 parts of 10% polyvinyl alcohol aqueous solution, 0.5 part of nonionic surfactant, water 150 Parts were blended and prepared, and a coating solution A was obtained.

2. Coating solution for thermosensitive coloring layer Coating solution B: The following developer dispersion, dye dispersion, and sensitizer dispersion were prepared and ground to an average particle size of 1 micron with a sand grinder. Next, 36.0 parts of developer dispersion, 9.2 parts of dye dispersion, 36.0 parts of sensitizer dispersion, 12.0 parts of kaolin clay (50% dispersion), nonionic surfactant 0.5 part was blended to obtain a coating solution B.

b1) Developer dispersion liquid 6.0 parts of 4-hydroxy-4'-isopropoxydiphenyl sulfone, 18.8 parts of a 10% aqueous polyvinyl alcohol solution and 11.2 parts of water were blended.
b2) Dye dispersion liquid 2.0 parts of 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 4.6 parts of 10% polyvinyl alcohol aqueous solution, and 2.6 parts of water were blended.
b3) Sensitizer dispersion 6.0 parts of parabenzylbiphenyl, 18.8 parts of a 10% polyvinyl alcohol aqueous solution, and 11.2 parts of water were blended.
The prepared coating liquid A and coating liquid B were simultaneously coated on a base paper by a multilayer slide curtain coating method and then dried to obtain a thermal recording paper. The coating speed at that time was 1000 m / min. Formed coating layer is a coating layer B on the coating layer A, on which a base paper, the coating amount after drying, the coating layer A is 8 g / m ^2, the coating layer B is 2 g / m ² met It was. The curtain coating film was stable and good coating was possible.

[Example 2]
Instead of simultaneous coating on the base paper 1, the coating liquid A is dried and then slit-coated so that the coating amount becomes 8 g / m ² , and then dried, and further the coating liquid B is slit to make ² g / m ^2. A heat-sensitive recording paper was obtained in the same manner as in Example 1 except that it was applied and dried.

[Comparative Example 1]
A thermal recording paper was obtained in exactly the same manner as in Example 2, except that the coating liquids A and B were applied to one side of the base paper 1 in this order by a bar blade and dried.

(Characteristic evaluation of coating solution)
The characteristics of the coating solutions A and B were evaluated for the following items.
1) Surface tension It measured at 25 degreeC using the surface tension meter.
2) B type viscosity It measured at 25 degreeC using the B type viscometer.
3) Contact angle The contact angle between the coating film and the base paper was measured.
4) Zaan cup viscosity Using a Zaan cup (NO.3), the coating solution was dropped from the prepared hole in the cup, and the time until the solution in the cup disappeared was measured.
5) Ductility In the Zahn cup viscosity measurement, when the liquid falling from the cup pilot hole was cut, the length of the liquid until it was cut was measured.

(Evaluation of thermal recording printing)
1) Thermal printability (dynamic color density)
Printing was performed on the recording paper with an applied energy of 0.41 mJ / dot using a thermal recording paper printing tester (equipped with TH-PMD manufactured by Okura Electric Co., Ltd. and thermal head manufactured by Kyocera Corporation). The recording density of the recording part was measured with a Macbeth densitometer (RD-914, using an amber filter).
2) Evaluation of printability Using 0.5 mL of UV ink manufactured by Toyo Ink Co., Ltd., RI printing was performed on the test piece obtained by cutting the above recording paper into a width of 3 cm and a length of 20 cm, and a visual evaluation was performed on the thermal recording paper. Normal printability was evaluated.
○: No white spots occur and printability is good. Δ: Some white spots occur and printability is slightly poor. ×: Many white spots occur and it is difficult to print on a thermal recording medium.

(Evaluation of bulkiness)
The density of the heat-sensitive recording paper before printing was measured by a conventional method to evaluate the bulkiness.

  The obtained results are shown in Table 2. Table 4 summarizes the characteristics evaluation of the coating solution.

As is apparent from Table 2, in Examples 1 and 2, the thermal printability (dynamic color density), printability, and bulkiness are all excellent. On the other hand, in the case of Comparative Example 1 in which bar blade coating was performed, the thermal printability (dynamic color density) and printability were reduced, and the paper density was increased due to pressing during application, and the bulkiness was also reduced. .
In addition, according to Examples 1 and 2, it was found that the thermal recording paper of this embodiment is excellent not only in thermal printability but also in normal printability. The reason for this is not clear, but may be related to the high flexibility of bulky paper.
[Example 3]

(Manufacture of inkjet recording paper)
1. Coating liquid for ink receiving layer Coating liquid C: 100 parts of synthetic amorphous silica, 25 parts of polyvinyl alcohol, 10 parts of ethylene vinyl acetate copolymer emulsion, 5 parts of nonionic SB latex, 8 parts of ink fixing agent,
Defoaming agent 0.2 part, cationic sizing agent 3 parts, bluing agent 0.005 part, nonionic surfactant 0.5 part and fluorescent dye 0.5 part are added to water, solid content concentration The coating liquid C was 20%.

2. Coating liquid for ink receiving layer (cationic colloidal silica layer) Coating liquid D: 100 parts of cationic chain colloidal silica having a particle diameter of 90 nm, 6 parts of dye fixing agent, 3 parts of cationic sizing agent, nonionic surfactant 5 parts and 0.2 part of antifoaming agent were added to water, and it was set as the coating liquid D with a solid content concentration of 15%.
After drying the coating liquid C on the base paper 1 so as to have a coating amount of 15 g / m ² after drying, and then drying the coating liquid D so that the coating liquid D becomes ² g / m ^2. Inkjet recording paper was obtained. The coating speed was 1000 m / min.

[Comparative Example 2]
An ink jet recording paper was manufactured in exactly the same manner as in Example 3, except that the coating liquids C and D were applied to one side of the base paper 1 in this order by the bar blade.

[Comparative Example 3]
An ink jet recording paper was produced in exactly the same manner as in Example 3 except that the base paper 12 was used.

(Characteristic evaluation of coating solution)
The characteristics of the coating liquids C and D were evaluated for the same items as the coating liquids A and B.

(Evaluation of printing for inkjet recording)
The following items were evaluated. If the evaluation is ◎ or ○, there is no practical problem, but if it is Δ or ×, there is a practical problem.

1) Color density Black (BK), cyan (C), magenta (M), and yellow (Y) solid images with spreadsheet software “Excel” using an inkjet printer (PM-970C, manufactured by Seiko Epson) Produced. In the settings of the printer driver attached to the printer, “Super fine” was selected for the print quality and “Glossy paper” was selected for the paper, and this image was printed. The recording paper after printing was left in a constant temperature and humidity room for one day, and then the printing density of each color was measured using a Macbeth densitometer (RD915, manufactured by Macbeth), and the average value was taken as the average density.
A: The average density is 1.8 or more. B: The average density is in the range of 1.7 to less than 1.8. Δ: The average density is in the range of 1.6 to less than 1.7. Concentration is less than 1.6

2) Roundness Using the above printer and spreadsheet software, a gray image was prepared and printed, the printed part was magnified 250 times with a microscope, and the dot shape was visually evaluated.
◎: The outline is almost a perfect circle. ○: The outline is smooth and the shape is almost circular. △: The outline is distorted and is an ellipse rather than a circle. ×: The outline is jagged and difficult to say as a circle.

3) Ink absorbability Using the above printer and spreadsheet software, a pattern in which magenta and green solid images are adjacent to each other was produced and printed, and bleeding (bleed) at the boundary portion was visually evaluated. Since the blurring at the boundary between magenta and green is black, a more rigorous evaluation is possible.
◎: No bleeding at the boundary part ○: Little bleeding at the boundary part △: Slight bleeding at the boundary part X: Slight bleeding at the boundary part

4) Surface strength of recording paper Paste cello tape (registered trademark) on the recording surface (ink receiving layer surface), rub it strongly 20 times with a rubber roller on top of it, fix the end of the tape only to the spring, and 180 ° in a U-shape On the contrary, the tape was bent and pulled in this direction, and the scale when the tape was peeled was measured and evaluated.
◎: Peel strength is 500 g or more ○: Peel strength is in the range of 300 g to less than 500 g △: Peel strength is in the range of 200 g to less than 300 g ×: Peel strength is in the range of less than 200 g

5) Cracking of coating layer The recording surface (ink receiving layer surface) was magnified 300 times with an electron microscope, and the form was visually evaluated.
A: No cracks (cracks) are observed at all. ○: Some cracks (cracks) are observed (1-2 pieces / one field of view). Δ: Many cracks (cracks) are observed (5-10 pieces / field of view). : Cracks (cracks) are observed on the entire surface (10 or more per field of view)

(Evaluation of bulkiness)
The density of the heat-sensitive recording paper before printing was measured by a conventional method to evaluate the bulkiness.

  The obtained results are shown in Table 3. Table 4 summarizes the characteristics evaluation of the coating solution.

As is apparent from Table 3, in the case of Example 3 where curtain coating was performed using a bulky base paper obtained by making a paper stock containing an organic compound that inhibits the interfiber bonding of pulp, ink jet printability, ink absorptivity, coating layer Both strength and bulkiness are excellent. On the other hand, in the case of the comparative example 2 which performed bar blade coating, all evaluation fell and bulkiness also fell (density became high). Moreover, in the case of the comparative example 3, the bulkiness fell.
As shown in Table 4, the characteristics of the coating liquids A to D were all found to be excellent in curtain coating suitability at high speed.

Claims (8)

  A method for producing an information recording paper, wherein one or more coating liquids are applied by a curtain method to the surface of a low-density base paper containing an organic compound that inhibits interfiber bonding of pulp.   When 0.3 parts by weight of the organic compound is blended with respect to 100 parts by weight of the dry weight of the pulp, the tensile strength of the low density base paper according to JIS-P8113 is blended with the organic compound using the pulp. 2. The method of manufacturing an information recording paper according to claim 1, wherein the tensile strength is 5 to 30% lower than that of the paper not to be printed.   3. The method for producing an information recording sheet according to claim 1, wherein the coating liquid contains 0.2 to 2.0 parts by weight of a surfactant with respect to 100 parts by weight of the pigment.   4. The information recording sheet according to claim 1, wherein an angle formed between the liquid film falling during curtain coating of the coating liquid and the low-density base paper is 25 ° to 110 °. Method. 5. The method for producing an information recording paper according to claim 1, wherein the density is 1.20 g / cm ³ or less.   6. The method for producing an information recording paper according to claim 1, wherein the coating liquid has a surface tension of 45 mN / m or less.   The method for producing an information recording paper according to any one of claims 1 to 6, wherein the coating solution has a B-type viscosity of 50 to 2000 mPa · s. The information recording paper according to any one of claims 1 to 7, wherein a Zahn cup viscosity of the coating liquid used for the curtain coating is 10 to 300 seconds, and a ductility at the time of measuring the viscosity is 15 cm or more. Manufacturing method.