WO2011001706A1 - Paper for recording of information and processed paper - Google Patents

Abstract

Disclosed is a paper for recording information or a processed paper in which one or more coating layers are provided on one surface or both surfaces of a support material. The paper is characterized in that the outermost layer in the coating layers comprises cellulose nanofibers. In the paper, carboxyl groups present on the surfaces of the cellulose nanofibers at a high density can form a strong bond to cellulose fibers that constitute a paper or a binder, a pigment or the like that is contained in a coating solution, thereby improving the film strength of the coating layer and enhancing the adhesion of the coating layer to a paper underlying the coating layer. In this manner, general printing properties of the paper can be improved.

Description

Information recording paper and processed paper

The present invention relates to an information recording paper or processed paper having an outermost surface layer containing cellulose nanofibers and having excellent general printability and the like among coating layers provided on a support.

Cellulose contained in higher plants such as wood has a form of a fiber aggregate formed by combining fibrous cellulose microfibrils having a width of about 3 to 4 nm and a crystallinity of 75 to 85% with a lignin component. . Many attempts have been made to obtain nanofibers (also referred to as “cellulose nanofiber” or “CNF”) by separating the fiber assembly into microfibrils (Patent Document 1, etc.), and the obtained nanofiber is a nanomaterial. As such, it is expected to be applied to many uses (Patent Document 2 etc.).
On the other hand, information recording paper represented by thermal recording media, pressure-sensitive copying paper, ink jet paper, thermal transfer paper, electrophotographic transfer paper, processed paper represented by release paper, moisture-proof wrapping paper, and wallpaper have various functions. In general, one or more coating layers containing a pigment or a binder are provided on one or both sides of the support.

For example, a colorless or light-colored electron-donating leuco dye (hereinafter referred to as “dye”) and an electron-accepting developer (hereinafter referred to as “developer”) such as a phenolic compound are finely divided. After grinding and dispersing into particles, mix the two and add a binder, filler, sensitivity improver, lubricant and other auxiliaries to obtain a coating solution such as paper, synthetic paper, film, plastic, etc. A thermal recording material obtained by coating on a support can obtain a recorded image by developing a color by an instantaneous chemical reaction by heating with a thermal head, hot stamp, thermal pen, laser light, or the like. (Patent Documents 3, 4 etc.).
In addition, as an ink jet recording medium having a configuration suitable for the ink jet recording method, for example, when simply recording characters, a plain paper type medium that is directly recorded on paper is used, and when high resolution and color reproducibility are desired. A coated paper type medium provided with an ink receiving layer as the coating layer is used. In particular, when a high gloss level comparable to that of a silver salt photograph is required, a cast coated paper type medium in which a coated paper type coating layer is formed by a casting method is used. As an inkjet recording medium having a texture close to that of general coated paper, an ink receiving layer on the lower side mainly containing kaolin and amorphous synthetic silica on the surface of the support, and an ink on the upper side mainly containing vapor phase method alumina. Those having a receiving layer are disclosed (Patent Documents 5 to 7, etc.).

International Publication WO2009 / 084566 International Publication WO2009 / 112982 JP 2001-121823 (Patent No. 4223644) International Publication WO2002 / 020277 JP 2005-103827 A JP 2005-297473 A JP 2004-209965 A

Printing on information recording paper such as heat-sensitive recording paper and ink jet recording paper in advance, and printing and recording on the information recording paper has been increasing, but a coating layer was provided for each of these applications. When general printing such as offset printing or gravure printing is performed on information recording paper or processed paper, problems such as poor ink fixing properties of the coating layer and picking during printing have occurred.
This ink fixing failure means that the ink does not fix on the printed paper surface, and is considered to be caused by the low affinity between the ink and the coating layer and the low permeability of the ink to the coating layer. It has been. Picking refers to the fluffing of paper that occurs during printing, and the strength of the outermost coating layer (also referred to as surface strength) is weaker than the ink adhesion to the coated surface. It is thought to be caused by. The fact that such a problem does not occur during printing is called “general printability”.
Therefore, an object of the present invention is to provide an information recording paper and a processed paper excellent in general printability. In particular, the present invention is a thermal recording material excellent in color development (contrast between the printed portion and blank paper portion), scratch resistance, and general printability (ink fixing property, picking resistance), and scratch resistance of the pigment ink printed portion. Another object is to provide an ink jet recording medium excellent in printing quality.

In the information recording paper and processed paper in which at least one coating layer is provided on one side or both sides of the support, the above-mentioned problem is that the outermost layer of the coating layer contains cellulose nanofibers. It has been found that this problem can be solved by adopting a configuration.
When the coating liquid is applied to the paper surface, it is considered that the coating liquid penetrates into the paper and forms a coating layer integrally with the surface portion of the paper. By incorporating cellulose nanofibers in the outermost layer of the coating layer, the carboxyl groups, etc. that exist at high density on the surface of the cellulose nanofibers are strong with the cellulose fibers that make up the paper and binders and pigments added to the coating solution. By forming a strong bond, while maintaining the permeability of the ink and the like to the coating layer, improve the film strength of the coating layer, and further strengthen the adhesion between the coating layer and the paper below it, It is considered that general printing characteristics have been improved.
In particular, for thermal recording media, by including cellulose nanofibers in the outermost layer of the thermal recording layer and any protective layer provided as a coating layer on the thermal recording media, general printability (ink fixability, picking resistance) ) And color development were found to be improved.
In addition, for ink jet recording papers, it has been found that blending cellulose nanofibers in the ink receiving layer, which is the outermost layer, improves general printability and scratch resistance.

That is, the present invention is an information recording paper or processed paper in which at least one coating layer is provided on one side or both sides of a support, and the outermost layer of the coating layer contains cellulose nanofibers and a binder.
The present invention also provides the information recording paper, wherein a heat-sensitive recording layer containing a colorless or light-colored electron-donating leuco dye and an electron-accepting developer is provided as a coating layer on the support, and the heat-sensitive recording layer is provided. It is a heat-sensitive recording material whose layer is the outermost layer.
The present invention also relates to the information recording paper, an ink jet recording medium in which an ink receiving layer is provided as a coating layer on a support, and the ink receiving layer is the outermost layer.

Information recording paper and processed paper with the coating layer containing cellulose nanofibers as the outermost layer have excellent general printability (ink fixability, picking resistance). In addition, when cellulose nanofibers are included in the protective layer of the thermal recording medium, it has good ink fixing properties and picking resistance when printed on the thermal recording medium, and also has excellent color development (printed and blank paper areas). Contrast) and scratch resistance. Further, by blending cellulose nanofibers in the ink receiving layer of the ink jet recording paper, the ink jet recording paper is excellent in printability and scratch resistance.

The support used in the present invention is not particularly limited as long as it can be applied with a coating solution containing cellulose nanofibers, and may be appropriately selected depending on the application. Examples of such a support include paper, recycled paper, synthetic paper, film, plastic film, foamed plastic film, non-woven fabric, and a composite sheet obtained by combining these.
At least one coating layer is provided on one side or both sides of the support depending on the application.
The outermost layer of this coating layer contains cellulose nanofibers. The content of the cellulose nanofibers in the coating layer is desirably prepared as appropriate depending on the application, but generally, it is preferably 0.004 parts by weight or more with respect to 100 parts by weight of the solid content of the coating layer. More preferably, it is 0.005 parts by weight or more, and still more preferably 0.008 to 70 parts by weight. When there is one coating layer, that layer is the outermost layer. In addition, the coating layers other than the outermost layer may contain cellulose nanofibers.
It is desirable to appropriately adjust the solvent of the coating solution and the concentration of the cellulose nanofiber depending on the application.
Examples of the information recording paper include thermal recording media, pressure-sensitive copying paper, inkjet paper, thermal transfer paper, electrophotographic transfer paper, and the like, and examples of processed paper include release paper, moisture-proof wrapping paper, and wallpaper.

Cellulose nanofibers The cellulose nanofibers used in the present invention can be obtained by defibrating (miniaturizing) a cellulose-based raw material by chemical treatment or mechanical treatment.
As a method for producing cellulose nanofibers used in the present invention, a cellulose raw material such as finely divided cellulose oxidized by a catalyst is defibrated by a high-pressure homogenizer (cellulose nanofibers obtained by chemical treatment), a cellulose raw material Examples of the suspension obtained by defibration and classification using glass or zirconia beads as a grinding medium (cellulose nanofibers by mechanical treatment) can be exemplified, and the method is not limited to these production methods. However, from the viewpoint of improving the strength of the protective layer of the heat-sensitive recording material, it is particularly preferable to use cellulose nanofibers produced by performing an oxidation treatment with a catalyst.

A preferred method for producing cellulose nanofibers comprises using an oxidizing agent in the presence of a compound selected from the group consisting of (1) N-oxyl compounds and (2) bromides, iodides and mixtures thereof. And oxidizing the cellulose to prepare oxidized cellulose, and wet oxidizing atomization treatment of the oxidized cellulose to form nanofibers.

The cellulose-based raw material is not particularly limited, and is made from various wood-derived kraft pulp or sulfite pulp, powdered cellulose obtained by pulverizing them with a high-pressure homogenizer or a mill, or chemical treatment such as acid hydrolysis. Purified microcrystalline cellulose powder and the like can be used. In addition, plants such as kenaf, hemp, rice, bagasse and bamboo can also be used. Among these, when bleached kraft pulp, bleached sulfite pulp, powdered cellulose, and microcrystalline cellulose powder are used, it is easy to handle and has a relatively low viscosity (2% (w / v) B-type viscosity of 500% in aqueous dispersion). Cellulose nanofibers of about 2000 mPa · s) can be efficiently produced, and powdered cellulose and microcrystalline cellulose powder are more preferable.

Powdered cellulose is a rod-like particle made of microcrystalline cellulose obtained by removing a non-crystalline part of wood pulp by acid hydrolysis and then pulverizing and sieving. The degree of polymerization of cellulose in powdered cellulose is preferably about 100 to 500, the degree of crystallinity of powdered cellulose by X-ray diffraction is preferably 70 to 90%, and the volume average particle size by a laser diffraction type particle size distribution analyzer. Is preferably 100 μm or less, more preferably 50 μm or less. When the volume average particle size is 100 μm or less, a cellulose nanofiber dispersion having excellent fluidity can be obtained. As the powdered cellulose used in the present invention, for example, a fixed particle size in the form of a rod shaft produced by a method of purifying and drying an undegraded residue obtained after acid hydrolysis of a selected pulp, pulverizing and sieving. A crystalline cellulose powder having a distribution may be used, or commercially available products such as KC Flock ^R (manufactured by Nippon Paper Chemicals Co., Ltd.), Theolas ^R (manufactured by Asahi Kasei Chemicals Co., Ltd.), and Avicel ^R (manufactured by FMC) may be used. .

As the N-oxyl compound used for oxidizing the cellulosic raw material, any compound can be used as long as it is a compound that promotes the target oxidation reaction. For example, examples of the N-oxyl compound used in the present invention include substances represented by the following general formula (Formula 1).

(Wherein R ¹ to R ⁴ each independently represents an alkyl group having about 1 to 4 carbon atoms.)
Among the compounds represented by the general formula (Formula 1), 2,2,6,6-tetramethyl-1-piperidine-N-oxy radical (hereinafter referred to as “TEMPO”), and 4-hydroxy-2,2 , 6,6-Tetramethyl-1-piperidine-N-oxy radical (hereinafter referred to as “4-hydroxy TEMPO”) is preferred. Further, a derivative obtained from TEMPO or 4-hydroxy TEMPO can also be preferably used, and in particular, a derivative of 4-hydroxy TEMPO can be most preferably used. The 4-hydroxy TEMPO derivative is a derivative obtained by etherifying the hydroxyl group of 4-hydroxy TEMPO with an alcohol having a linear or branched carbon chain having 4 or less carbon atoms, or esterified with a carboxylic acid or a sulfonic acid. The derivatives obtained are preferred. When etherifying 4-hydroxy TEMPO, if an alcohol having 4 or less carbon atoms is used, the resulting derivative becomes water-soluble regardless of the presence or absence of saturated or unsaturated bonds in the alcohol, making it an excellent oxidation catalyst. A functional 4-hydroxy TEMPO derivative can be obtained.

Examples of the 4-hydroxy TEMPO derivative include compounds represented by the following general formulas (Chemical Formulas 2 to 4).

(In the formula, R represents a linear or branched carbon chain having 4 or less carbon atoms.)

Furthermore, radicals of N-oxyl compounds represented by the following general formula (Chemical Formula 5), that is, azaadamantane type nitroxy radicals are particularly preferable because uniform cellulose nanofibers can be produced in a short time.

(In the formula, R ⁵ and R ⁶ each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms.)
The amount of the N-oxyl compound such as TEMPO or 4-hydroxyl TEMPO derivative used for oxidizing the cellulosic raw material is not particularly limited as long as it is a catalyst amount capable of converting the cellulosic raw material into nanofibers. For example, it is about 0.01 to 10 mmol, preferably about 0.01 to 1 mmol, and more preferably about 0.05 to 5 mmol, with respect to 1 g of cellulosic raw material.

As the bromide or iodide used in the oxidation of the cellulose-based raw material, a compound that can be dissociated and ionized in water, such as an alkali metal bromide or an alkali metal iodide, can be used. The amount of bromide or iodide used can be selected within a range that can promote the oxidation reaction. For example, it is about 0.1 to 100 mmol, preferably about 0.1 to 10 mmol, and more preferably about 0.5 to 5 mmol with respect to 1 g of cellulosic raw material.

As the oxidizing agent used for oxidizing the cellulosic raw material, the target oxidation reaction such as halogen, hypohalous acid, halous acid, perhalogen acid or salts thereof, halogen oxide, peroxide can be promoted. Any oxidizing agent can be used as long as it is an oxidizing agent. Among these, from the viewpoint of production cost, sodium hypochlorite, which is the most widely used in industrial processes and has a low environmental load, is particularly suitable. The amount of the oxidizing agent used can be selected within a range that can promote the oxidation reaction. For example, it is about 0.5 to 500 mmol, preferably 0.5 to 50 mmol, and more preferably about 2.5 to 25 mmol with respect to 1 g of cellulosic raw material.

As described above, the oxidation of the cellulosic raw material in the present invention includes the presence of a compound selected from the group consisting of (1) N-oxyl compounds such as 4-hydroxy TEMPO derivatives and (2) bromides, iodides, and mixtures thereof. Below, it is characterized by oxidizing a cellulosic raw material in water using an oxidizing agent such as sodium hypochlorite. This method is characterized in that the oxidation reaction of the cellulosic raw material can proceed smoothly and efficiently even under mild conditions. Therefore, the reaction temperature may be about 15 to 30 ° C. In addition, since the carboxyl group produces | generates through an aldehyde group in a cellulose with progress of reaction, the fall of pH of a reaction liquid is recognized. In order to advance the oxidation reaction efficiently, it is desirable to maintain the pH of the reaction solution at about 9 to 12, preferably about 10 to 11, by adding an alkaline solution such as an aqueous sodium hydroxide solution.

Cellulose nanofibers can be produced by subjecting the cellulose-based raw material oxidized as described above to wet atomization and defibrating. As the wet atomization treatment, for example, a mixing / stirring and emulsifying / dispersing device such as a high-speed shear mixer or a high-pressure homogenizer can be used alone or in combination of two or more. In particular, when wet atomization is performed using an ultrahigh pressure homogenizer that enables a pressure of 100 MPa or more, preferably 120 MPa or more, more preferably 140 MPa or more, a relatively low viscosity (2% (w / v) aqueous dispersion Cellulose nanofibers having a B-type viscosity of about 500 to 2000 mPa · s) can be efficiently produced, which is preferable.

The B-type viscosity (60 rpm, 20 ° C.) of the cellulose nanofibers at a concentration of 2% (w / v) (that is, 2 g of cellulose nanofibers (dry mass) is contained in 100 ml of dispersion) is 500 to 7000 mPa · s. An aqueous dispersion of cellulose nanofibers, preferably 500 to 2000 mPa · s, is desirable because it can be suitably used as a paint. A relatively low B-type viscosity in a 2% (w / v) aqueous dispersion of cellulose nanofibers is preferable because it is easy to handle when preparing a coating, and specifically, 500 to 2000 mPa · s. About 500 to 1500 mPa · s, more preferably about 500 to 1000 mPa · s.
The B-type viscosity of the aqueous dispersion of cellulose nanofibers of the present invention can be measured by a known method. For example, it can be measured using a VICOMETER TV-10 viscometer manufactured by Toki Sangyo.

The width and length of the cellulose nanofiber obtained by the above method can be controlled by the oxidation treatment time, the wet atomization treatment time or the treatment pressure. The viscosity of the cellulose nanofiber dispersion can be controlled by the oxidation treatment time, the wet atomization treatment time or the treatment pressure, and the amount of carboxyl groups can be adjusted by changing the oxidation treatment conditions.
The cellulose nanofiber used in the present invention preferably has a width of 0.5 to 20 nm and a length of 0.1 to 15 μm, and more preferably a width of 2 to 5 nm and a length of 1 to 5 μm.
In addition, the carboxyl group amount of the cellulose nanofiber is preferably 0.3 to 5 mmol / g, and more preferably 0.8 to 2 mmol / g.
The amount of carboxyl groups in cellulose nanofibers was prepared by adding 60 ml of a 0.5% by weight slurry of cellulose nanofibers, adding 0.1M hydrochloric acid aqueous solution to pH 2.5, and then dropping 0.05N sodium hydroxide aqueous solution dropwise. Then, the electrical conductivity is measured until the pH reaches 11, and can be calculated from the amount of sodium hydroxide (a) consumed in the weak acid neutralization stage where the change in electrical conductivity is gradual, using the following equation. .
Carboxyl group amount [mmol / g pulp] = a [ml] × 0.05 / oxidized pulp mass [g]

Application to thermal recording media:
Hereinafter, embodiments in which the present invention is applied to a thermal recording material will be described.
The heat-sensitive recording material has a heat-sensitive recording layer on the support and optionally a protective layer on the heat-sensitive recording layer. The heat-sensitive recording layer may be the outermost layer without providing the protective layer, or the protective layer may be provided as the outermost layer by providing a protective layer. In addition, an undercoat layer (underlayer) may be provided between the support and the heat-sensitive recording layer, or an intermediate layer may be provided between the heat-sensitive recording layer and the protective layer.
It is preferable that the coating layer containing cellulose nanofibers further optionally contains a pigment and / or a binder.
The protective layer is usually about 1 to 5 g / m ² , the thermosensitive recording layer is usually about 2 to 12 g / m ² , and the undercoat layer is usually about 1 to 20 g / m ² .

Next, various materials used in the present invention are exemplified, but not only the coating layer containing cellulose nanofibers but also, for example, thermal recording of a thermal recording body, as long as the desired effect on the above-described problems is not impaired. It can also be used for each coating layer provided according to the layer, under layer, and other applications.

As the dye used in the heat-sensitive recording material of the present invention, any of those known in the field of conventional pressure-sensitive or heat-sensitive recording paper can be used, and is not particularly limited, but includes a triphenylmethane compound, a fluoran compound. Compounds, fluorene compounds, divinyl compounds and the like are preferable. Specific examples of typical colorless or light-colored basic colorless dyes are shown below. These basic colorless dyes may be used alone or in combination of two or more.

<Triphenylmethane leuco dye>
3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis (p-dimethylaminophenyl) phthalide (also known as malachite green lactone)

<Fluoran leuco dye>
3-diethylamino-6-methylfluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (o, p-dimethylanilino) fluorane, 3-dibutylamino -6-methyl-fluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7- (o, p-dimethylanilino) fluorane, 3-dibutylamino- 7- (o-chloroanilino) fluorane, 3-dibutylamino-7- (o-fluoroanilino) fluorane, 3-n-dipentylamino-6-methyl-7-anilinofluorane, 3- (N-ethyl- N-isoamylamino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-N-isoamylamino) -6-chloro-7- Nirinofuruoran, 3-cyclohexylamino-6-chloro-fluoran

<Divinyl leuco dye>
3,3-bis- [2- (p-dimethylaminophenyl) -2- (p-methoxyphenyl) ethenyl] -4,5,6,7-tetrabromophthalide, 3,3-bis- [2- (P-dimethylaminophenyl) -2- (p-methoxyphenyl) ethenyl] -4,5,6,7-tetrachlorophthalide, 3,3-bis- [1,1-bis (4-pyrrolidinophenyl) ) Ethylene-2-yl] -4,5,6,7-tetrabromophthalide, 3,3-bis- [1- (4-methoxyphenyl) -1- (4-pyrrolidinophenyl) ethylene-2- Yl] -4,5,6,7-tetrachlorophthalide

<Others>
3- (4-Diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (4-diethylamino-2-ethoxyphenyl) -3- ( 1-octyl-2-methylindol-3-yl) -4-azaphthalide, 3- (4-cyclohexylethylamino-2-methoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl)- 4-azaphthalide, 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide, 3,6-bis (diethylamino) fluorane-γ- (3′-nitro) anilinolactam, 3,6 -Bis (diethylamino) fluorane-γ- (4'-nitro) anilinolactam, 1,1-bis- [2 ', 2', 2 ", 2" -tetrakis- (p-dimethylamino) Enyl) -ethenyl] -2,2-dinitrileethane, 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2- β-naphthoylethane, 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2,2-diacetylethane, bis- [2, 2,2 ′, 2′-Tetrakis- (p-dimethylaminophenyl) -ethenyl] -methylmalonic acid dimethyl ester

As the developer used in the present invention, any known developer in the field of conventional pressure-sensitive or heat-sensitive recording paper can be used, and is not particularly limited. For example, activated clay, attapulgite, colloidal silica Inorganic acidic substances such as aluminum silicate, 4,4′-isopropylidenediphenol, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 4 , 4′-dihydroxydiphenyl sulfide, hydroquinone monobenzyl ether, benzyl 4-hydroxybenzoate, 4,4′-dihydroxydiphenyl sulfone, 2,4′-dihydroxydiphenyl sulfone, 4-hydroxy-4′-isopropoxydiphenyl sulfone, 4-hydroxy-4'-n-propoxydiphenyl Lufone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'-methyldiphenylsulfone, 4-hydroxyphenyl-4'-benzyloxyphenylsulfone, 3,4-dihydroxyphenyl-4'-methyl Phenylsulfone, aminobenzenesulfonamide derivative described in JP-A-8-59603, bis (4-hydroxyphenylthioethoxy) methane, 1,5-di (4-hydroxyphenylthio) -3-oxapentane, bis (p -Hydroxyphenyl) butyl acetate, methyl bis (p-hydroxyphenyl) acetate, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,4-bis [α-methyl-α- (4'- Hydroxyphenyl) ethyl] benzene, 1,3-bis [α-methyl-α- (4′-hydro Cyphenyl) ethyl] benzene, di (4-hydroxy-3-methylphenyl) sulfide, 2,2′-thiobis (3-tert-octylphenol), 2,2′-thiobis (4-tert-octylphenol), International Publication WO97 No. 16420, a phenolic compound such as a diphenylsulfone cross-linking compound, a phenolic compound described in International Publication WO 02/081229 or JP-A No. 2002-301873, an international publication WO 02/098774 or WO 03/029017 Phenol novolac type condensation compositions, urea urethane compounds described in International Publication WO00 / 14058 or JP-A-2000-143611, thiourea compounds such as N, N′-di-m-chlorophenylthiourea, p-chlorobenzoic acid, Stearyl gallate Bis [4- (n-octyloxycarbonylamino) salicylate] dihydrate, 4- [2- (p-methoxyphenoxy) ethyloxy] salicylic acid, 4- [3- (p-tolylsulfonyl) propyloxy ] Salicylic acid, 5- [p- (2-p-methoxyphenoxyethoxy) cumyl] aromatic carboxylic acid of salicylic acid, and zinc, magnesium, aluminum, calcium, titanium, manganese, tin, nickel of these aromatic carboxylic acids, etc. Examples thereof include salts with polyvalent metal salts, zinc antithiline complexes of zinc thiocyanate, and complex zinc salts of terephthalaldehyde acid with other aromatic carboxylic acids. These developers can be used alone or in combination of two or more. In addition, a metal chelate color-developing component such as higher fatty acid metal double salts and polyvalent hydroxyaromatic compounds described in JP-A-10-258577 can also be contained.

In addition, a conventionally known sensitizer can be used as long as it does not inhibit the desired effect. Examples of such a sensitizer include fatty acid amides such as stearic acid amide and palmitic acid amide, ethylene bisamide, montanic acid wax, and polyethylene. Wax, 1,2-di- (3-methylphenoxy) ethane, p-benzylbiphenyl, β-benzyloxynaphthalene, 4-biphenyl-p-tolyl ether, m-terphenyl, 1,2-diphenoxyethane, Shu Dibenzyl oxalate, di (p-chlorobenzyl) oxalate, di (p-methylbenzyl) oxalate, dibenzyl terephthalate, benzyl p-benzyloxybenzoate, di-p-tolyl carbonate, phenyl-α-naphthyl carbonate, 1 , 4-Diethoxynaphthalene, 1-hydroxy-2-naphthoic acid Phenyl ester, o-xylene-bis- (phenyl ether), 4- (m-methylphenoxymethyl) biphenyl, 4,4′-ethylenedioxy-bis-benzoic acid dibenzyl ester, dibenzoyloxymethane, 1,2 -Di (3-methylphenoxy) ethylene, bis [2- (4-methoxy-phenoxy) ethyl] ether, methyl p-nitrobenzoate, phenyl p-toluenesulfonate Is not to be done. These sensitizers may be used alone or in combination of two or more.

The type and amount of the dye, developer, and other various components used in the heat-sensitive recording layer of the present invention are determined according to the required performance and recording suitability, and are not particularly limited. About 0.5 to 10 parts of developer and 0.5 to 10 parts of pigment are used with respect to 1 part, and the binder is suitably about 5 to 25% in the solid content of the heat-sensitive recording layer.
The cellulose nanofiber content is preferably about 5 to 30 parts by weight, more preferably 6 to 15 parts by weight based on 100 parts by weight of the total solid content of the heat sensitive recording layer when blended in the heat sensitive recording layer which is the outermost layer. In the case of blending into the protective layer which is the outermost layer, it is preferably about 20 to 70 parts by weight, more preferably 30 to 50 parts by weight with respect to 100 parts by weight of the total solid content of the protective layer.

The binder used in the present invention includes fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, acetoacetylated polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, amide-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, butyral-modified polyvinyl alcohol, and olefin-modified. Polyvinyl alcohol, nitrile modified polyvinyl alcohol, pyrrolidone modified polyvinyl alcohol, silicone modified polyvinyl alcohol, other modified polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer and Cell like ethyl cellulose, acetyl cellulose Derivatives, casein, arabic gum, oxidized starch, etherified starch, dialdehyde starch, esterified starch, polyvinyl chloride, polyvinyl acetate, polyacrylamide, polyacrylic ester, polyvinyl butyral, polystyrose and copolymers thereof Polyamide resin, silicone resin, petroleum resin, terpene resin, ketone resin, coumaro resin and the like can be exemplified.
Among these, it is preferable to contain a water-soluble polymer such as starch, polyvinyl alcohol, methylcellulose, carboxymethylcellulose, and a binder such as a synthetic resin emulsion such as a styrene / butadiene copolymer and an acrylic acid copolymer. It is preferable to include a binder having a refractive index of 1.48 to 1.50 such as polyvinyl alcohol or acrylic resin having a refractive index close to that of cellulose.
These polymer substances are used by dissolving in water, alcohol, ketones, esters, hydrocarbons and other solvents, and are used in the form of emulsification or paste dispersion in water or other media. It can also be used in combination.

Examples of the pigment used in the present invention include kaolin, (calcined) kaolin, calcium carbonate, aluminum oxide, titanium oxide, magnesium carbonate, aluminum silicate, magnesium silicate, calcium silicate, aluminum hydroxide, silica, and various organic pigments. However, it is not limited to these.

Examples of the crosslinking agent used in the present invention include glyoxal, methylol melamine, melamine formaldehyde resin, melamine urea resin, polyamine epichlorohydrin resin, polyamide epichlorohydrin resin, potassium persulfate, ammonium persulfate, sodium persulfate, chloride chloride Examples include ferric iron, magnesium chloride, borax, boric acid, alum, ammonium chloride and the like.

Examples of the lubricant used in the present invention include fatty acid metal salts such as zinc stearate and calcium stearate, waxes, and silicone resins.
Further, in the present invention, 4,4′-butylidene (6-tert-butyl-3-methylphenol) is used as an image stabilizer exhibiting the oil resistance effect of a recorded image within a range not inhibiting the desired effect on the above problems. ), 2,2′-di-t-butyl-5,5′-dimethyl-4,4′-sulfonyldiphenol, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) Butane, 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 4-benzyloxy-4 ′-(2,3-epoxy-2-methylpropoxy) diphenylsulfone, etc. Can also be added.
In addition, benzophenone and triazole ultraviolet absorbers, dispersants, antifoaming agents, antioxidants, fluorescent dyes, and the like can be used.

In the heat-sensitive recording material of the present invention, the dye, the developer, and the material to be added as necessary are fine particles until a particle size of several microns or less is obtained by a pulverizer such as a ball mill, an attritor, a sand glider, or an appropriate emulsifier. Depending on the binder and purpose, various additive materials are added to form a coating solution. As the solvent used in the coating solution, water, alcohol or the like can be used, and its solid content is about 20 to 40% by weight.

Dye, developer, and materials to be added as needed are finely pulverized to a particle size of several microns or less with a pulverizer such as a ball mill, attritor or sand glider or an appropriate emulsifier, and depending on the binder and purpose. Various additive materials are added to form a coating solution. As the solvent used in the paint, water, alcohol or the like can be used, and its solid content is about 20 to 40%. Further, the means for applying is not particularly limited, and can be applied according to well-known conventional techniques. For example, various coaters such as an air knife coater, rod blade coater, vent blade coater, bevel blade coater, roll coater, curtain coater, etc. The provided off-machine coating machine or on-machine coating machine is appropriately selected and used. The heat-sensitive recording material of the present invention can further be provided with an under layer comprising a filler and a binder between the support and the heat-sensitive recording material for the purpose of increasing the color development sensitivity. It is also possible to correct the curl by providing a backcoat layer on the opposite side of the support from the thermosensitive recording layer. Further, various known techniques in the heat-sensitive recording material field, such as supercalendering after the application of each layer, can be added as appropriate.

Application to inkjet recording media:
Hereinafter, embodiments in which the present invention is applied to an ink jet recording medium will be described.
As the support, either a gas permeable support or a non-air permeable support can be used, but a gas permeable support is preferred. Examples of the non-permeable support include films of cellophane, polyethylene, polypropylene, soft polyvinyl chloride, hard polyvinyl chloride, polyester, polyolefin resin-coated paper, metal foil, synthetic paper, and non-woven fabric. A preferable air-permeable support is a base paper mainly composed of wood pulp.
An ink receiving layer is provided on this base paper.

Before providing the ink receiving layer, the base paper may be impregnated or coated with a size press solution prepared from starch, polyvinyl alcohol, sizing agent, or the like for the purpose of enhancing paper strength or imparting size. The impregnation or application method is not particularly limited, but may be carried out by an impregnation method represented by a pound type size press, or an application method represented by a rod metalling size press, a gate roll coater, or a blade coater. preferable. Further, when impregnating or applying the size press solution, as long as the effects of the present invention are not impaired, a fluorescent dye, a conductive agent, a water retention agent, a water resistance agent, a pH adjuster, an antifoaming agent, Auxiliaries such as lubricants, preservatives, surfactants and the like can be mixed in an arbitrary ratio.

As the pigment of the ink receiving layer, any known pigment used for general offset printing coated paper may be used. Examples of inorganic pigments include, for example, kaolin, silica such as synthetic amorphous silica, heavy calcium carbonate, light calcium carbonate, silica-calcium carbonate composite particles, talc, calcined kaolin obtained by calcining the kaolin, calcium sulfate, barium sulfate, dioxide One type or two or more types can be appropriately selected and used from titanium, zinc oxide, alumina, magnesium carbonate, magnesium oxide, calcium silicate, bentonite, zeolite, sericite, smectite, and the like.
The mixing ratio of the inorganic pigment in the ink receiving layer is 65 to 88 parts by weight, preferably 70 to 80 parts by weight with respect to 100 parts by weight of the entire ink receiving layer (solid content).

In order to improve the white paper glossiness of the ink receiving layer surface, the ink receiving layer can contain an organic pigment such as a plastic pigment. The blending ratio of the organic pigment is preferably at most 40 parts by weight, more preferably at most 30 parts by weight with respect to 100 parts by weight of the inorganic pigment.

As the organic pigment, a solid type, a hollow type, or a core-shell type can be used alone or in combination of two or more as required. As the constituent polymer component of the organic pigment, a monomer such as styrene and / or methyl methacrylate is preferably used as a main component, and other monomers copolymerizable with these are used as necessary. Examples of other copolymerizable monomers include olefinic aromatic monomers such as α-methylstyrene, chlorostyrene, and dimethylstyrene, methyl (meth) acrylate, ethyl (meth) acrylate, and (meth) acrylic. And monoolefin monomers such as butyl acid, 2-ethylhexyl (meth) acrylate, glycidyl (meth) acrylate, and (meth) acrylonitrile; and monomers such as vinyl acetate.

In addition to the main monomer and other monomers described above, olefinic unsaturated carboxylic acid monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid and crotonic acid; hydroxyethyl, methacrylic Olefinic unsaturated hydroxy monomers such as hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate; olefins such as acrylamide, methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, and N-methoxymethylacrylamide Saturated amide monomers: Dimer vinyl monomers such as divinylbenzene can be used singly or in combination of two or more. These monomers are exemplary, and other monomers can be used as long as they are copolymerizable monomers.

The content of cellulose nanofibers in the ink receiving layer is 0.004 to 2.3 parts by weight, more preferably 0.008 to 0.8 parts by weight with respect to 100 parts by weight of the entire ink receiving layer (solid content). is there.

Any binder may be used as the binder used in the ink receiving layer as long as it is a publicly known binder used for offset printing coated paper or an inkjet recording medium. Examples of the binder include starches such as oxidized starch, etherified starch and esterified starch; latexes such as styrene / butadiene copolymer (SB) latex and acrylonitrile / butadiene copolymer (NB) latex; polyvinyl alcohol and One or two or more kinds thereof can be appropriately selected from binders such as modified products thereof, casein, gelatin, carboxymethylcellulose, polyurethane, vinyl acetate, and unsaturated polyester resins.

The ratio of the binder is preferably 4 parts by mass or more and 35 parts by mass or less, and more preferably 5 parts by mass or more and less than 30 parts by mass with respect to 100 parts by mass in total of all inorganic pigments contained in the ink receiving layer. . When the content of the binder is less than 4 parts by mass, the strength of the ink receiving layer tends to be insufficient. On the other hand, when the content of the binder exceeds 35 parts by mass, voids existing in the ink receiving layer are filled with the binder, and the ink absorption capacity decreases, so that it is difficult to obtain good print quality. is there.

For the ink receiving layer, pigment dispersant, thickener, water retention agent, lubricant, antifoaming agent, foam suppressor, mold release agent, foaming agent, coloring dye, coloring pigment, fluorescent dye, antiseptic, etc. Auxiliaries such as agents, water-resistant agents, surfactants, pH adjusters and the like can be added as appropriate.

The coating amount of the ink receiving layer is not formed in particular limited, it is less than per one side 1 g / ^{m 2} or more 40 g / ^{m 2} is preferable, and 4g / ^{m 2} or more 30 g / ^m less than ² per side preferable. The greater the coating amount, the greater the amount of voids in the ink receiving layer, and the better the ink absorbability.

As a method for providing an ink receiving layer on a base paper, blade coating, roll coating, air knife coating, bar coating, gate roll coating, curtain coating, gravure coating, flexographic gravure coating, and spray coating are common coating devices. Various coating apparatuses such as a size press can be used on-machine or off-machine.

Further, the ink receiving layer containing cellulose nanofibers may be provided on one side or both sides of the base paper, and may be provided in one layer or two or more layers. In the present invention, sufficient performance can be obtained even if there is only one ink-receiving layer. Therefore, it is preferable to provide only one ink-receiving layer from the viewpoint of cost reduction. The ink receiving layer containing cellulose nanofibers is preferably the outermost layer, and an ink receiving layer or an undercoat layer not containing cellulose nanofibers may be provided under the ink receiving layer containing cellulose nanofibers.

The following examples illustrate the invention but are not intended to limit the invention.
Parts and% indicate parts by weight and% by weight, respectively.

[Production Examples 1 to 3]
15 g of powdered cellulose (manufactured by Nippon Paper Chemical Co., Ltd., particle size: 24 μm) was added to 500 ml of an aqueous solution in which 78 mg (0.5 mmol) of TEMPO (Sigma Aldrich) and 755 mg (7 mmol) of sodium bromide were dissolved, Stir until the powdered cellulose is uniformly dispersed. After adding 50 ml of sodium hypochlorite aqueous solution (effective chlorine 5%) to the reaction system, the pH was adjusted to 10.3 with 0.5N hydrochloric acid aqueous solution, and the oxidation reaction was started. During the decreasing reaction, the pH in the system was adjusted to pH 10 by successively adding a 0.5N aqueous sodium hydroxide solution. After reacting for 2 hours, oxidized powdered cellulose was separated by centrifugal operation (6000 rpm, 30 minutes, 20 ° C.) and sufficiently washed with water to obtain oxidized powdered cellulose. Oxidized 2% (w / v) slurry of powdered cellulose was treated with a mixer at 12,000 rpm for 15 minutes, and the powdered cellulose slurry was further treated with an ultra-high pressure homogenizer (pressure 140 MPa), and the following three types A transparent dispersion of cellulose nanofibers was obtained.
In addition, the width | variety and length of a cellulose nanofiber are randomly extracted from the photograph of the cellulose nanofiber image | photographed with the electron microscope (100 pieces), and are the measured average values.
-Cellulose nanofiber 1: Width 2.1 nm, Length 1.5 μm Solid content 2%
Cellulose nanofiber 2: width 4.9 nm, length 4.8 μm, solid content 2%
Cellulose nanofiber 3: B-type viscosity (60 rpm, 20 ° C.) in an aqueous dispersion having a concentration of 1% (w / v) is 3000 mPa · s, and the carboxyl group amount is 1.2 mmol / g.

First, a heat-sensitive recording material was produced as follows.
The following materials were mixed to prepare an under layer coating solution.
[Under layer coating solution]
Baked kaolin (manufactured by Engelhard, trade name: Ancilex 93, average particle size 3 μm) 30% dispersion 100 parts Styrene-butadiene copolymer latex (solid content 48%) 40 parts Fully saponified polyvinyl alcohol (PVA117) 10 % Aqueous solution 30 parts Water 160 parts

The developer dispersion liquid (A liquid), leuco dye dispersion liquid (B liquid), and sensitizer dispersion liquid (C liquid) having the following composition are each wetted separately with a sand grinder until the average particle diameter becomes 0.5 μm. Grinding was performed.
Liquid A (developer dispersion)
4-hydroxy-4'-isopropoxydiphenylsulfone (manufactured by Nippon Soda Co., Ltd., D8) 6.0 parts polyvinyl alcohol 10% aqueous solution 18.8 parts water 11.2 parts B liquid (dye dispersion)
3-Dibutylamino-6-methyl-7-anilinofluorane (Oda-2, Yamada Chemical Co., Ltd.) 2.0 parts Polyvinyl alcohol 10% aqueous solution 4.6 parts Water 2.6 parts C solution (sensitizer dispersion) liquid)
Dibenzyl oxalate 6.0 parts Polyvinyl alcohol 10% aqueous solution 18.8 parts Water 11.2 parts

Subsequently, the dispersion liquid was mixed at the following ratio to prepare a coating liquid for the heat-sensitive recording layer.
[Thermosensitive recording layer coating solution 1]
Liquid A (developer dispersion) 36.0 parts Liquid B (dye dispersion) 13.8 parts Liquid C (sensitizer dispersion) 36.0 parts Carboxyl-modified polyvinyl alcohol (PVA-KL318) 10%
Aqueous solution 25 parts Silica (manufactured by Mizusawa Chemical Co., Ltd., trade name: Mizukasil P603) 30% dispersion 10 parts

The following materials were mixed in an environment of 40 ° C. or lower to prepare a protective layer coating solution.
[Protective layer coating solution 1]
Cellulose nanofiber 1 2% dispersion 225 parts Carboxyl-modified polyvinyl alcohol (PVA-KL318) 10%
Aqueous solution 30.0 parts Zinc stearate (manufactured by Chukyo Yushi Co., Ltd., trade name: Hydrin Z-7-30,
Solid content 30%) 2.0 parts Polyamide epichlorohydrin resin (manufactured by Seiko PMC, trade name: WS4
030, solid content: 25%) 2.0 parts modified polyamide resin (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumirez resin SPI)
106N) 0.5 part Aluminum hydroxide (manufactured by Martinsberg, trade name: Martyfine OL) 50% aqueous solution 3.0 parts

[Protective layer coating solution 2]
Cellulose nanofiber 1 2% dispersion 225 parts Carboxyl-modified polyvinyl alcohol (PVA-KL318) 10%
Aqueous solution 30.0 parts Zinc stearate (manufactured by Chukyo Yushi Co., Ltd., trade name: Hydrin Z-7-30,
Solid content 30%) 2.0 parts Polyamide epichlorohydrin resin (manufactured by Seiko PMC, trade name: WS4
030, solid content: 25%) 2.0 parts modified polyamide resin (manufactured by Sumitomo Chemical Co., Ltd., trade name: Sumirez resin SPI)
106N) 0.5 part

[Example 1]
The under layer coating liquid was applied to one side of a base paper (support) of 60 g / m ² and then dried to obtain an under coated paper having a coating amount of 10.0 g / m ² .
Next, the thermal recording layer coating liquid 1 was applied onto the under layer so as to have a coating amount of 4.0 g / m ² and dried.
Next, the protective layer coating liquid 1 was applied onto the heat-sensitive recording layer so as to be 2.0 g / m ² and dried. This sheet was processed with a super calendar so that the Beck smoothness was 1200 seconds to produce a heat-sensitive recording material.
[Example 2]
A thermosensitive recording material was produced in the same manner as in Example 1 except that the cellulose nanofiber 1 in the protective layer coating solution 1 was changed to the cellulose nanofiber 2.
[Example 3]
A thermosensitive recording material was produced in the same manner as in Example 1 except that the 10% aqueous solution of carboxy-modified polyvinyl alcohol in the protective layer coating solution 1 was changed to a 10% solution of acrylic emulsion (trade name: Barrier Star B1000, manufactured by Mitsui Chemicals). .
[Example 4]
A thermosensitive recording material was produced in the same manner as in Example 1 except that the amount of cellulose nanofiber 1 in the protective layer coating solution 1 was reduced to 150 parts.

[Example 5]
A heat-sensitive recording material was prepared in the same manner as in Example 1 except that the polyamide epichlorohydrin resin and the modified polyamide resin were removed from the protective layer coating solution 1.
[Example 6]
A heat-sensitive recording material was prepared in the same manner as in Example 1 except that the aluminum hydroxide of the protective layer coating solution 1 was changed to silica (manufactured by Mizusawa Chemical Co., Ltd., trade name: Mizukasil P537).
[Example 7]
A thermosensitive recording material was produced in the same manner as in Example 1 without adding 150 parts by weight of cellulose nanofiber 1 to the thermosensitive recording layer coating solution 1 and without applying the protective layer coating solution 1.
[Example 8]
A heat-sensitive recording material was prepared in the same manner as in Example 7 except that the 30% silica dispersion of the heat-sensitive recording layer coating solution 1 was changed to a 50% aqueous solution of aluminum hydroxide (manufactured by Martinsberg, trade name: Martinfin OL). did.
[Example 9]
A heat-sensitive recording material was produced in the same manner as in Example 7 except that the cellulose nanofiber 1 in the heat-sensitive recording layer coating solution 1 was changed to the cellulose nanofiber 2.

[Comparative Example 1]
A thermosensitive recording material was produced in the same manner as in Example 1 except that the cellulose nanofiber 1 was removed from the protective layer coating solution 1.
[Comparative Example 2]
A thermosensitive recording material was produced in the same manner as in Example 1 except that the cellulose nanofibers 1 in the protective layer coating solution 1 were changed to carboxymethylcellulose (manufactured by Nippon Paper Chemicals, trade name: Sunrose F30MG).
[Comparative Example 3]
A thermosensitive recording material was produced in the same manner as in Example 1 except that the cellulose nanofiber 1 of the protective layer coating solution 1 was changed to methyl cellulose (trade name: Metrolse SM100, manufactured by Shin-Etsu Chemical Co., Ltd.).
[Comparative Example 4]
A thermosensitive recording material was produced in the same manner as in Example 1 except that the cellulose nanofiber 1 of the protective layer coating solution 1 was changed to an acrylic resin (trade name: Barrier Star B1000, manufactured by Mitsui Chemicals, Inc.).
[Comparative Example 5]
A thermosensitive recording material was produced in the same manner as in Example 1 except that 50 parts by weight of cellulose nanofiber 1 was added to thermosensitive recording layer coating solution 1 and cellulose nanofiber 1 was removed from protective layer coating solution 1.

[Example 10]
The under layer coating solution was applied to one side of a support (60 g / m ² base paper) and then dried to obtain an under coated paper having a coating amount of 10.0 g / m ² .
Next, the thermal recording layer coating liquid 1 was applied onto the under layer so as to have a coating amount of 4.0 g / m ² and dried.
Next, the protective layer coating liquid 2 was applied onto the heat-sensitive recording layer so as to be 2.0 g / m ² and dried. This sheet was processed with a super calendar so that the Beck smoothness was 1200 seconds to produce a heat-sensitive recording material.
[Example 11]
A thermosensitive recording material was produced in the same manner as in Example 10 except that the cellulose nanofiber 1 in the protective layer coating solution 2 was changed to the cellulose nanofiber 2.
[Example 12]
A thermosensitive recording material was produced in the same manner as in Example 10 except that the 10% aqueous solution of carboxy-modified polyvinyl alcohol in the protective layer coating solution 2 was changed to a 10% solution of acrylic emulsion (trade name: Barrier Star B1000, manufactured by Mitsui Chemicals). .
[Example 13]
A thermosensitive recording material was produced in the same manner as in Example 10 except that the amount of cellulose nanofiber 1 in the protective layer coating solution 2 was reduced to 150 parts.

[Example 14]
A thermosensitive recording material was prepared in the same manner as in Example 10 except that 150 parts by weight of cellulose nanofiber 1 was added to the thermosensitive recording layer coating solution 1 and the protective layer coating solution 2 was not applied.
[Example 15]
1.5 parts by weight of polyamide epichlorohydrin resin (manufactured by Seiko PMC, trade name: WS4030, solid content: 25%) and modified polyamide resin (manufactured by Sumitomo Chemical Co., trade name: Sumi) A heat-sensitive recording material was prepared in the same manner as in Example 14 by adding 0.3 part by weight of the laser resin SPI106N).
[Example 16]
A heat-sensitive recording material was produced in the same manner as in Example 14 except that the cellulose nanofiber 1 in the heat-sensitive recording layer coating solution 1 was changed to the cellulose nanofiber 2.

[Comparative Example 6]
A heat-sensitive recording material was produced in the same manner as in Example 10 except that the cellulose nanofiber 1 was removed from the protective layer coating solution 2.
[Comparative Example 7]
A thermosensitive recording material was produced in the same manner as in Example 10 except that the cellulose nanofiber 1 of the protective layer coating solution 2 was changed to silica (manufactured by Mizusawa Chemical Co., Ltd., trade name: Mizukasil P537).
[Comparative Example 8]
A thermosensitive recording material was produced in the same manner as in Example 10 except that the cellulose nanofiber 1 of the protective layer coating solution 2 was changed to kaolin (trade name: Capim CC, manufactured by Capim).
[Comparative Example 9]
A thermosensitive recording material was produced in the same manner as in Example 10 except that 150 parts by weight of cellulose nanofiber 1 was added to the thermosensitive recording layer coating solution 1 and the cellulose nanofiber 1 was removed from the protective layer coating solution 2.

The following evaluation was performed about the heat-sensitive recording material obtained above.
<Evaluation of color development sensitivity>
The produced thermal recording material was printed with an applied energy of 0.42 mJ / dot using a thermal recording paper printing tester (TH-PMD manufactured by Okura Electric Co., Ltd., equipped with a thermal head manufactured by Kyocera Corporation). The recording density of the recording part was measured and evaluated with a Macbeth densitometer (RD-914).
The larger the value, the higher the color sensitivity and the better the contrast.

<Image quality evaluation>
The solid print portion was visually evaluated.
Good: Printed with clear black Impossibility: The whole is blurred white <Abrasion evaluation>
The coated surface was visually evaluated for rubbing color development with steel wool to which a load of 1000 g / cm ² was applied.
Good: Almost no color development Yes: Light color development No: Dark color development

<Dry picking strength evaluation>
The degree of picking when printing black ink (Dainippon Ink Co., Ltd .: Space Color Fusion G, ink deposit 0.15 cc) with an RI printing machine (Made Manufacturing Co., Ltd.) was visually evaluated.
Good: Almost no fuzz or paper peeling Yes: Slight fuzz or paper peeling is not possible No: Many fuzz and paper peeling are seen

<Wet picking strength evaluation>
When the surface of the thermal recording paper is moistened with a water supply roll and then printed with red ink (Dainippon Ink Co., Ltd .: Space Color Fusion G, ink accumulation 0.15 cc) with an RI printer (Made Manufacturing Co., Ltd.) The degree of picking was visually evaluated.
Good: Almost no fuzz or paper peeling Yes: Slight fuzz or paper peeling is not possible No: Many fuzz and paper peeling are seen

The results are shown in Table 1.

Note: PVA: Carboxyl-modified polyvinyl alcohol; EP: Polyamide epichlorohydrin resin; PA: Modified polyamide resin; Alumina: Aluminum hydroxide; CNF: Cellulose nanofibers (the numbers represent the number of cellulose nanofibers)

Next, the ink jet recording medium was prepared as follows.
[Production Example 4]
Addition of 0.5% of cationized starch to pulp, 0.05% of alkyl ketene dimer to pulp, and 2% of sulfate band to pulp with respect to 100% by mass of hardwood bleached kraft pulp (freeness 400ml) Then, 12% of calcium carbonate was added to the pulp, and 0.3 part of an ester compound of polyhydric alcohol and fatty acid (product name: KB-115, manufactured by Kao) was added as a densification chemical to obtain a paper material. Using this paper stock, an on-top twin-wire paper machine is used to form a web, dry it by performing a three-stage wet press, and then apply a 10% by weight aqueous oxidized starch solution again with a two-roll size press coater. This was dried to obtain a base paper having a basis weight of 80 g / m ² .

[Example 17]
Kaolin A (product name: ECLIPS650, manufactured by Engelhard) 80 parts, gel silica A (product name: NIPGEL AY-200, manufactured by Tosoh Silica) 20 parts, organic pigment A (product name: P8900, manufactured by Asahi Kasei Chemicals) ) 10 parts, 0.5 part of cellulose nanofiber 3 and 10 parts of SB latex (glass transition temperature 15 ° C.), 0.2 part of sodium hydroxide, 0.25 part of sodium polyacrylate as a dispersant, and diluted water By mixing, a paint having a solid content of 51% was obtained.
This paint was applied to both sides of the base paper obtained in Production Example 4 using a blade coater so that the coating amount per side was 12 g / m ² . The coating speed at this time was 500 m / min. After coating, the paper was dried until the moisture content in the paper became 5%, and was subjected to supercalender treatment so that the glossiness of white paper at a light incident angle of 75 degrees based on JIS-Z 8741 was 60% to obtain an ink jet recording medium.

[Example 18]
Supercalender treatment was performed in the same manner as in Example 17 except that the blending amount of cellulose nanofiber 3 was set to 2 parts so that the glossiness of blank paper at a light incident angle of 75 degrees based on JIS-Z 8741 was 60%. An ink jet recording medium was obtained.
The solid content of the paint of Example 2 was 30%, and it was necessary to reduce the coating speed to 200 m / min in order to manage the moisture in the paper with a blade coater.
[Example 19]
Except that the blending amount of the cellulose nanofiber 3 was 0.01 part, it was the same as in Example 17 so that the white paper glossiness at a light incident angle of 75 degrees based on JIS-Z 8741 was 60%. The inkjet recording medium was obtained by processing.
[Comparative Example 10]
Supercalender treatment in the same manner as in Example 17 except that the cellulose nanofiber 3 in the coating was not blended so that the white paper glossiness at a light incident angle of 75 degrees based on JIS-Z 8741 was 30%. As a result, an ink jet recording medium was obtained.

The following evaluation was performed about the inkjet recording medium obtained above.
Printing was performed using a commercially available pigment inkjet printer (manufactured by Seiko Epson, GP-700), and printing was evaluated according to the following evaluation method. The glossiness of the white paper is determined according to JIS-Z 8741. A glossiness meter (manufactured by Murakami Color Research Laboratory, True GLOSS GM-26PRO) is used, and the glossiness of the white paper having a light incident angle of 75 degrees with respect to the surface of the ink receiving layer. Was measured.

<Dryness (ink absorbability)>
A black straight line with a thickness of 1.5 points was printed with the above printer (photo paper / clean mode), rubbed with a finger 10 minutes after printing, and the drying property was evaluated according to the following criteria.
Good: The printed part hardly extends even when rubbed with a finger, and the ink absorption speed is fast and good.
Yes: When the finger is rubbed, the printed part is slightly extended and the ink absorption speed is slightly slow, but there is no practical problem.
Impossibility: When rubbed with a finger, the printed part is extended, the ink absorption speed is slow, and it is not practical.
<Abrasion resistance of printed part>
Five black straight lines with a thickness of 1.5 points are printed side by side with the above inkjet printer (photo paper / clean mode), and rubbed with a dry cotton swab 10 minutes and 5 hours after printing. Evaluated.
Good: The ink does not peel off even when rubbed with a cotton swab.
Yes: The ink peels off slightly when rubbed with a cotton swab, but there is no practical problem.
Impossible: The ink peels off when rubbed with a cotton swab and cannot be used practically.

<Border blur between colors>
The ink jet printer (photographic paper / clean mode) was used to print a pattern in which black characters entered a yellow solid part, and the bleeding of the characters was evaluated visually.
Good: No bleeding at all and good.
Possible: Slightly blotted in the yellow solid part, but no problem in practical use.
Impossible: It is bleeds so bad that it cannot be put to practical use.
<Surface strength>
Using a RI printer, printing was performed using special ink SMX tack grade 15 manufactured by Toyo Ink Co., Ltd., and the state of the printed surface after printing was evaluated according to the following criteria.
Good: No problem on the surface.
Yes: Slightly peeled, but practically durable.
Impossible: It peels off badly and cannot withstand practical use.

The obtained results are shown in Table 2. (CNF: cellulose nanofiber 3)

Claims (7)

1. An information recording paper or processed paper in which at least one coating layer is provided on one side or both sides of a support, and the outermost layer of the coating layer contains cellulose nanofibers.
2. In the presence of a compound selected from the group consisting of (1) N-oxyl compounds and (2) bromides, iodides and mixtures thereof, the cellulose nanofibers oxidize cellulosic materials using an oxidizing agent. The information recording paper or processed paper of Claim 1 manufactured by the method including the process of preparing the oxidized cellulose, and the process of wet- atomizing the oxidized cellulose and making it nanofiber.
3. The information recording paper or processed paper according to claim 1 or 2, wherein the coating layer which is the outermost layer further contains a pigment.
4. The information recording sheet is a thermal recording medium, pressure-sensitive copying paper, inkjet paper, thermal transfer paper, or electrophotographic transfer paper, and the processed paper is release paper, moisture-proof wrapping paper, or wallpaper. The information recording paper or processed paper according to any one of the above.
5. The information recording paper according to any one of claims 1 to 3, comprising a colorless or light-colored electron-donating leuco dye and an electron-accepting developer as a coating layer on a support. A heat-sensitive recording material comprising a layer, wherein the heat-sensitive recording layer is the outermost layer.
6. The information recording paper according to any one of claims 1 to 3, comprising a colorless or light-colored electron-donating leuco dye and an electron-accepting developer as a coating layer on a support. And a protective layer on the thermosensitive recording layer, and the protective layer is the outermost layer.
7. 4. The information recording paper according to claim 3, wherein an ink receiving layer is provided as a coating layer on a support, and the ink receiving layer is an outermost layer.