JP2003291542A - Heat-sensitive recording paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-sensitive recording paper excellent in the resistance to ground fogging and the storage property of a recording section. <P>SOLUTION: In the heat-sensitive recording paper having a heat-sensitive recording layer containing a leuco dye and a colorant on a paper support containing a waste paper pulp to be obtained by applying an ink-removing treatment to waste paper such as news papers, printed fine-quality sheets or the like, as one means for solving the problem, the heat-sensitive recording layer contains the colorant of 100 to 500 pts.wt. such as an N-p-toluenesulfonyl-N '-3-(p-toluenesulfonyloxy)phenylurea to 4,4'-bis[(4-methyl-3- phenoxycarbonylaminophenyl)ureido]diphenylsufone. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosensitive recording paper which utilizes a color reaction between a leuco dye and a color former.

[0002]

2. Description of the Related Art A heat-sensitive recording paper is well known in which a recording image is obtained by heat by utilizing a coloring reaction between a leuco dye and a color developing agent. Since such thermal recording paper is relatively inexpensive, and the recording device is compact and easy to maintain, it can be used not only as a recording medium such as an output of a facsimile or various computers, a printer of a scientific measuring instrument, etc., but also as a POS. It is widely used as a recording medium for various printers such as labels, ATMs, CADs, handy terminals, and various ticket papers.

[0003] With the expansion of applications of thermal recording paper, there is an increasing demand for thermal recording paper using a paper support containing waste paper pulp. When a paper support containing waste paper pulp is used, for example, it is printed. There is a problem that the density of the recording portion decreases with time due to the influence of a nonionic surfactant or the like used in the production of used paper pulp by deinking used paper.

By the way, in International Patent Publication WO00 / 14058 and International Patent Publication WO00 / 35679, 4,4'-bis [(4- Methyl-3-phenoxycarbonylaminophenyl) ureido] diphenyl sulfone, or Np
-Toluenesulfonyl-N'-3- (p-toluenesulfonyloxy) phenylurea and other heat-sensitive recording materials using urethane-based compounds are described, and heat-sensitive recording paper using a paper support containing waste paper pulp is also specified. It is described in JP-A-4-12892 and JP-A-4-78572.

However, 4,4'-bis [(4-methyl-3
-Phenoxycarbonylaminophenyl) ureido] diphenyl sulfone or Np-toluenesulfonyl-
When N'-3- (p-toluenesulfonyloxy) phenylurea is used in combination with other coloring agents, background fogging occurs over time, and when a paper support containing waste paper pulp is used, There is a problem that the concentration decreases with time.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermosensitive recording paper which is excellent in resistance to fog in the background and is excellent in preservability of the recording portion.

[0007]

[Means for Solving the Problems] In a thermal recording paper having a thermal recording layer containing a leuco dye and a color former on a paper support containing waste paper pulp, as one means for solving the above problems The thermosensitive recording layer contains 4,4'-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenyl sulfone.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In a heat-sensitive recording paper having a heat-sensitive recording layer containing a leuco dye and a color former on a paper support containing waste paper pulp, 4,4'-bis [( 4-Methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone (hereinafter referred to as a specific compound), thereby making the concentration of the recording part by the nonionic surfactant used in the production of waste paper pulp. It is possible to obtain a special effect with less deterioration and excellent fog resistance to the bare skin.

The use ratio of the specific compound contained in the heat-sensitive recording layer is not particularly limited, but is preferably about 2 to 30% by weight, more preferably 3% by weight with respect to the heat-sensitive recording layer.
It is about 20% by weight.

The content ratio of waste paper pulp in the paper support is preferably about 20 to 95% by weight based on the paper support. If the content of waste paper is less than 20% by weight, the curl resistance after recording (characteristic with less curl curl) is remarkably reduced, and if it exceeds 95% by weight, the tear strength of the paper support is lowered and the heat sensitivity is lowered. Since it may be difficult to process the recording paper into a small roll shape having a paper width of 40 to 70 mm, it is more preferably 40 to 80% by weight.

The raw materials for waste paper pulp include, for example, magazines,
Mainly used printed paper such as leaflets, newspapers, carbonless papers, and copy papers, and may further include spoiled paper such as fine paper and coated paper generated during paper production.

[0012] Waste paper pulp is generally used as a disintegration process of waste paper and broke with a low-concentration pulper or a high-concentration pulper, a rough selection process with a screen or a cleaner and a fine selection process, a deinking process with a flotation method or a water washing method, and chlorine bleaching ,
It can be obtained by appropriately combining bleaching steps such as chlorine dioxide bleaching, sodium hypochlorite bleaching and oxygen bleaching.

The paper support is composed of waste paper pulp and, if necessary, mainly wood pulp, non-wood pulp, synthetic pulp,
Pulp fibers for papermaking such as inorganic fibers are used. For example, the beating degree is Canadian Standard Freeness (hereinafter C
It is obtained by papermaking a pulp slurry of about 150 to 500 ml in SF).

In particular, the nonionic surfactant used in the deinking process during the production of waste paper pulp is contained in an amount of 1.0 × 10 ^{−3 to} 1.0 × 10 ⁻¹ % by weight based on the heat-sensitive recording paper. By doing so, excellent effects can be obtained due to the resistance to background fog and the storage stability over time of the recording area.

Further, in the paper support, talc, kaolin, clay, calcined kaolin, light (heavy) calcium carbonate, aluminum hydroxide, titanium oxide, magnesium silicate, magnesium sulfate, aluminosilicate, silica, bentonite. Inorganic filler such as polystyrene resin particles,
Urea formalin resin fine particles, heat-expandable fine hollow particles, and other organic fillers are appropriately contained.

In the pulp slurry, a sizing agent such as rosin type, petroleum resin type, alkyl ketene dimer type, alkenyl succinic anhydride type and stearic anhydride type, anionic type, cationic type, nonionic type, or amphoteric polyacrylamide is used. Organic compounds such as polymers, polyethyleneimine and its derivatives, polyamines, polyamide polyamines and their derivatives, polyethylene oxide, plant gum, polyvinyl alcohol, cationic latex, cationic urea formalin resin, melamine formalin resin, polyamide resin, etc. A dye, a pH adjuster, a pitch control agent, an antifoaming agent and the like can be appropriately added if necessary.

As the papermaking method, acidic papermaking or neutral papermaking is carried out by a usual papermaking machine such as fourdrinier, cylinder and various twin wires. A method such as a cylinder dryer, a Yankee dryer or an air dryer can be used in the drying step. Further, the surface may be appropriately coated with a surface sizing agent, a surface paper strength agent, an antistatic agent, a dye or the like by a method such as a size press, and the surface smoothness can be increased by calendering. After that, it may be used as a support.

Various known leuco dyes and coloring agents can be used. Specific examples of leuco dyes include, for example, 3,3-bis (p-dimethylaminophenyl) -6.
-Dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3-diethylamino-7-dibenzylamino-benzo [a] Blue-coloring dyes such as fluoran,

3- (N-ethyl-Np-tolyl) amino-7-N-methylanilinofluorane, 3-diethylamino-7-anilinofluorane, 3-diethylamino-7-dibenzylaminofluorane Green coloring dyes such as

3-cyclohexylamino-6-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-chlorofluorane, rhodamine (o-chloroanilino) lactam, 3
-Diethylamino-6,8-dimethylfluorane and other red-coloring dyes,

3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-
Methyl-N-cyclohexyl) amino-6-methyl-7
-Anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 3-di (n-pentyl) Amino-6-methyl-7-anilinofluorane, 3-diethylamino-7- (o-chlorophenylamino) fluorane, 3-di (n-butyl) amino-7- (o-fluorophenylamino) fluorane, 3
-(N-ethyl-p-toluidino) -6-methyl-7-
Anilinofluorane, 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-pyrrolidino- 6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-
Black coloring dyes such as Anilino Fluoran,

3,3-bis [1- (4-methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-
2-yl] -4,5,6,7-tetrachlorophthalide,
3-p- (p-dimethylaminoanilino) anilino-6
-Methyl-7-chlorofluorane, 3-p- (p-chloroanilino) anilino-6-methyl-7-chlorofluorane, 3,6-bis (dimethylamino) fluorene-9
Examples thereof include dyes having an absorption wavelength in the near infrared region such as -spiro-3 '-(6'-dimethylamino) phthalide.

Of course, the present invention is not limited to these,
Also, two or more kinds can be used in combination. The amount of the leuco dye include, but not be limited because it varies by color developer to be used ^is 0.1g / ^{m 2} ~1.0g / m 2 approximately.

Specific examples of the coloring agent include, for example, 4,4 '.
-Isopropylidene diphenol, 4,4'-cyclohexylidene diphenol, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 2,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfone , 4-hydroxy-4'-isopropoxydiphenyl sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'-methyldiphenyl sulfone, bis (p-hydroxyphenyl) butyl acetate, 1,1 -Phenolic compounds such as bis (4-hydroxyphenyl) -1-phenylethane, 1,4-bis [α-methyl-α- (4'-hydroxyphenyl) ethyl] benzene, Np-toluenesulfonyl-N '-3- (p-toluenesulfonyloxy) phenylurea, 4,4'-bis ( Compounds in -p- tolyl-sulfonylamino Carl isobornyl amino) molecules diphenylmethane having a urea bond, 4- [2-(p-methoxyphenoxy) ethyloxy] zinc salicylate, 4
Examples thereof include zinc salt compounds of aromatic carboxylic acids such as zinc [-(3- (p-tolylsulfonyl) propyloxy] salicylate and 5- [p- (2-p-methoxyphenoxyethoxy) cumyl] salicylic acid.

Among them, Np-toluenesulfonyl-
By using N'-3- (p-toluenesulfonyloxy) phenylurea in combination with a specific compound, excellent effects of recording sensitivity, background fogging resistance and chemical resistance can be obtained.

Particularly, it is preferable to use Np-toluenesulfonyl-N'-3- (p-toluenesulfonyloxy) phenylurea in an amount of about 100 to 500% by weight based on the specific compound.

The ratio of the leuco dye to the coloring agent used is appropriately selected according to the type of leuco dye or coloring agent used and is not particularly limited, but generally 1 part by weight of the leuco dye is used. 1 to 10 parts by weight, preferably 1 to
About 5 parts by weight of the coloring agent is used.

The heat-sensitive recording layer contains a specific compound in order to enhance the storage stability of a recorded image, but further contains other storability improving agent and a sensitizer in order to enhance the recording sensitivity. You can also

Specific examples of other storability improvers include, for example, 2,2'-methylenebis (4-methyl-6-tert-butylphenol) and 2,2'-ethylidenebis (4,6).
-Di-tert-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-tris (2-methyl-4-)
Hydroxy-5-cyclohexylphenyl) butane,
4,4'-thiobis (3-methylphenol), 2,2
-Bis (4-hydroxy-3,5-dibromophenyl)
Hindered phenol compounds such as propane, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane and 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 1,4-di Glycidyloxybenzene, 4,4'-diglycidyloxydiphenyl sulfone, 4-benzyloxy-4 '-(2-methylglycidyloxy) diphenyl sulfone, diglycidyl terephthalate, cresol novolac type epoxy resin, phenol novolac type epoxy resin, bisphenol Examples thereof include epoxy compounds such as A-type epoxy resin, N, N′-di-2-naphthyl-p-phenylenediamine, and bis (4-ethyleneiminocarbonylaminophenyl) methane.

Specific examples of the sensitizer include stearic acid amide, methylenebisstearic acid amide, dibenzyl terephthalate, 2-naphthylbenzyl ether, and m.
-Terphenyl, p-benzylbiphenyl, p-tolylbiphenyl ether, di (p-methoxyphenoxyethyl) ether, 1,2-di (3-methylphenoxy) ethane, 1,2-di (4-methylphenoxy) ethane ,
1,2-di (4-methoxyphenoxy) ethane, 1,2
-Di (4-chlorophenoxy) ethane, 1,2-diphenoxyethane, 1- (4-methoxyphenoxy) -2-
(3-methylphenoxy) ethane, p-methylthiophenylbenzyl ether, 1,4-di (phenylthio) butane, p-acetotoluidide, p-acetophenetizide, N-acetoacetyl-p-toluidine, di (β-biphenyl) Ethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1-isopropylphenyl-2-phenylethane, oxalic acid di-p-chlorobenzyl ester, oxalic acid di-p-methylbenzyl ester, oxalic acid dibenzyl ester, etc. Is mentioned.

The amounts of the other preservative-improving agents and sensitizers to be used are not particularly limited, but it is generally desirable to adjust the amount of each to be about 0.1 to 4 parts by weight per 1 part by weight of the color developing agent.

The heat-sensitive recording layer generally uses water as a dispersion medium,
A leuco dye, a coloring agent, a sensitizer, etc., if necessary, with a specific compound, or separately, and an average particle diameter of 2 μm by a stirrer / pulverizer such as a ball mill, attritor, or sand mill.
After finely pulverizing as follows, the coating liquid for heat-sensitive recording layer prepared by adding an adhesive is applied to one surface of the paper support so that the coating amount after drying is about 3 to 10 g / m ^2. It is formed by coating and drying.

Specific examples of the adhesive added to the coating liquid for the heat-sensitive recording layer include, for example, methyl cellulose, methoxy cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium carboxymethyl cellulose, cellulose, completely (partially) saponified polyvinyl alcohol, acetoacetyl. Modified polyvinyl alcohol, silicon modified polyvinyl alcohol, carboxy modified polyvinyl alcohol, sulfonic acid modified polyvinyl alcohol,
Polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch and its derivatives, casein, gelatin, alkali salt of styrene-maleic anhydride copolymer,
Water-soluble adhesives such as alkali salts of iso (or diiso) butylene-maleic anhydride copolymer, and water dispersibility of ethylene-vinyl acetate copolymer, acrylic latex, polyurethane latex, styrene-butadiene latex, etc. An adhesive may be used.

The amount of the adhesive used is about 5 to 50% by weight, preferably 5 based on the total solid amount of the coating liquid for the thermosensitive recording layer.
~ 30% by weight.

If necessary, various auxiliaries can be added to the heat-sensitive recording layer coating liquid. For example, sodium dioctyl sulfosuccinate, sodium dodecylbenzene sulfonate, lauryl alcohol sulfate ester
Surfactants such as sodium salt, fatty acid metal salt, polyethylene wax, carnauba wax, paraffin wax,
Waxes such as ester wax, kaolin, clay,
Talc, calcium carbonate, calcined kaolin, titanium oxide,
Amorphous silica, pigments such as aluminum hydroxide, glyoxal, formalin, glycine, glycidyl ester, glycidyl ether, dimethylol urea, ketene dimer, dialdehyde starch, melamine resin, polyamide resin, polyamide-epichlorohydrin resin, ketone-
Examples thereof include waterproofing agents such as aldehyde resins, borax, boric acid, ammonium zirconium carbonate, poamide amine / epiclohydrin resins, and other defoaming agents, fluorescent dyes, coloring dyes and the like.

In particular, by adding aluminum hydroxide having a volume average particle size of about 0.5 to 3 μm as a pigment in the heat-sensitive recording layer, the effect of further improving the heat-resistant background fog property at 80 to 100 ° C. can be obtained. . The ratio of aluminum hydroxide used is 3 to the heat-sensitive recording layer.
About 30% by weight is preferable.

A protective layer may be provided on the heat-sensitive recording layer in order to improve the chemical resistance and water resistance of the recording portion or to improve the recording running property. Such a protective layer is formed by, for example, applying a coating liquid for a protective layer containing an adhesive having a film-forming property onto the thermosensitive recording layer so that the coating amount after drying will be about 1 to 5 g / m ^2. It

As the adhesive contained in the coating liquid for the protective layer, for example, the adhesive contained in the coating liquid for the thermosensitive recording layer is used. Further, if necessary, various auxiliaries which can be contained in the heat-sensitive recording layer coating liquid are used in the protective layer coating liquid.

An undercoat layer is preferably formed between the paper support and the thermosensitive recording layer in order to enhance recording sensitivity.
The undercoat layer uses water as a medium and, for example, the coating amount after drying the undercoat layer coating liquid mainly containing a pigment and an adhesive is 3 to 15 g /
It is formed by coating and drying the surface of the paper support so as to be about m ² .

The pigment is not particularly limited, but JIS
-K-5101 has an oil absorption of 70 to 200 ml / 10
An oil-absorbing pigment of 0 g or organic hollow particles is particularly preferable because of excellent recording sensitivity. The average particle size of the pigment is about 0.5 to 20 μm, preferably about 0.5 to 5 μm.

Examples of the oil absorbing pigment include calcined kaolin, magnesium carbonate, amorphous silica, aluminum silicate, magnesium silicate, calcium silicate, calcium carbonate, urea-forlin resin filler and the like.

Examples of the organic hollow particles include vinyl chloride, vinylidene chloride, vinyl acetate, methyl acrylate,
Examples thereof include particles having a resin containing a monomer such as ethyl acrylate, methyl methacrylate, acrylonitrile, or styrene as a main component or a copolymer resin containing these monomers as a main component as a shell. The hollowness of the organic hollow particles (ratio of the volume of voids in particles to the total volume of particles) is 50 to
About 98% is preferable.

As the adhesive contained in the undercoat layer, the adhesive contained in the heat-sensitive recording layer is used. Furthermore,
The auxiliary agent contained in the above-mentioned heat-sensitive recording layer can be used in the undercoat layer.

The method of forming the undercoat layer, the heat-sensitive recording layer and the protective layer is not particularly limited, and examples thereof include air knife coating, varibar blade coating, pure blade coating, rod blade coating,
It is formed by a known appropriate coating method such as short dwell coating, curtain coating, die coating, and gravure coating.

The heat-sensitive recording paper of the present invention may be subjected to smoothing treatment such as super calendering after coating each layer, or may be provided with other layers such as a magnetic recording layer and an adhesive layer.

[0046]

The present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to these examples. In the examples and comparative examples, “parts” and “%” represent “parts by weight” and “% by weight”, respectively, unless otherwise specified.

Example 1 Preparation of Waste Paper Pulp A composition comprising 2 parts of newspaper waste paper, 3 parts of printed fine paper waste paper, 1 part of a 1% aqueous solution of caustic soda and 95 parts of water was disintegrated with a pulper and then screened. Dust removal treatment with a cleaner, dehydration treatment (pulp concentration 25%), bleaching with hydrogen peroxide and a nonionic surfactant (polyoxyethylene nonylphenyl ether), and deinking treatment. The diluted waste paper pulp after treatment was diluted to 1%, and then subjected to flotation and aqueous treatment to obtain waste paper pulp having a Hunter whiteness of 75%.

Preparation of paper support 80 parts of the above-mentioned waste paper pulp concentration 1% slurry (Canada standard freeness 210 ml) and pulp concentration 1% LBKP
After mixing at a ratio of 20 parts of slurry (Canadian standard freeness 480 ml), 0.3% of alkyl ketene dimer and 0.5% of cation-modified starch (trade name: Kate F, manufactured by Oji National Co., Ltd.) with respect to a paper support. %, A sulfuric acid band of 0.2%, and a light calcium carbonate of 7% were internally added to the pulp slurry using a long-paper machine, and the following size press liquid was applied at a coating amount of 1.0 g / Press to m ² and machine calender process to basis weight 5
A paper support having 0 g / m ² and a Bekk smoothness of 60 seconds on both sides was obtained. The content ratio of the nonionic surfactant (polyoxyethylene nonylphenyl ether) in the paper support was 5.1 × 10 ⁻³ % by weight based on the paper support.

Preparation of coating liquid for undercoat layer Baked kaolin [trade name: Ansilex 93, oil absorption 9
0 ml / 100 g, manufactured by EC Co., Ltd.] 80 parts, organic pigment [trade name: Grosdale 104S, solid content 46%] 40 parts, partially saponified polyvinyl alcohol 10% aqueous solution 70 parts, solid content concentration 48% styrene-butaciene System latex 1
A composition consisting of 5 parts, 2 parts of a 20% aqueous solution of sodium polyacrylate and 200 parts of water was mixed and stirred to obtain a coating liquid for the undercoat layer.

Preparation of Solution A A composition consisting of 40 parts of 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 20 parts of a 20% aqueous solution of polyvinyl alcohol modified with sulfonic acid and 40 parts of water was prepared. Liquid A was obtained by pulverizing with a sand mill until the average particle size became 1.0 μm or less.

Liquid B Preparation 4, 4'-Bis [(4-methyl-3-phenoxycarbonylaminophenyl) urea] diphenylsulfone 40
Part, a composition comprising 20 parts of a 20% aqueous solution of sulfone-modified polyvinyl alcohol and 40 parts of water were pulverized with a sand mill until the average particle size was 1.0 μm or less, to obtain a liquid B.

Preparation of solution C A composition consisting of 40 parts of Np-toluenesulfonyl-N'-3- (p-toluenesulfonyloxy) phenylurea, 20 parts of a 20% aqueous solution of sulphone-modified polyvinyl alcohol and 40 parts of water was prepared. Liquid C was obtained by pulverizing with a sand mill until the average particle size became 1.5 μm or less.

Preparation of solution D A composition consisting of 40 parts of 1,2-di (3-methylphenoxy) ethane, 20 parts of a 20% aqueous solution of sulfone-modified polyvinyl alcohol and 40 parts of water and having an average particle size of 1.5 μm was sand milled. It was pulverized to the following to obtain a liquid D.

Preparation of coating liquid for thermosensitive recording layer 25 parts of solution A, 10 parts of solution B, 50 parts of solution C, 50 parts of solution D, 80 parts of 10% aqueous solution of completely saponified polyvinyl alcohol,
Aluminum hydroxide with a volume average particle diameter of 1 μm (trade name:
Heidilite H-42, Showa Light Metal Industry Co., Ltd. 15
Parts, 5 parts of amorphous silica, 5 parts of calcium carbonate, and 10 parts of 36% dispersion of zinc stearate were mixed and stirred to obtain a coating liquid for heat-sensitive recording layer.

Preparation of coating liquid for protective layer 50 parts of aluminum hydroxide (Hijilite H-42, Showa Light Metal Industry Co., Ltd.), 5 parts of 10% aqueous solution of sodium polyacrylate (dispersing agent), zinc stearate 21% aqueous dispersion (Z-7, manufactured by Chukyo Yushi Co., Ltd.) of 50 parts, and 10% aqueous solution of carboxy-modified polyvinyl alcohol 400
Part, a composition of 10 parts of a 20% aqueous solution of a poamidoamine epiclohydrin resin and 100 parts of water were mixed and stirred to prepare a coating liquid for protective layer.

Preparation of thermal recording paper On one side of the paper support, the coating liquid for undercoat layer, coating liquid for thermal recording layer and coating liquid for protective layer were respectively applied at a coating amount of 8 g /
^{m 2, 4g / m 2,} 2g / m 2 and so as to sequentially applied and dried to subbing layer, the heat-sensitive recording layer to obtain a heat-sensitive recording paper to form a protective layer. After forming each layer, super calendering was applied to each layer, and the surface smoothness on the protective layer side was 12
It was 00 seconds. The content ratio of the nonionic surfactant (polyoxyethylene nonylphenyl ether) in the thermosensitive recording paper was 3.5 × 10 ⁻³ % by weight based on the thermosensitive recording paper.

Example 2 In preparation of the coating liquid for the thermosensitive recording layer of Example 1, B solution 10
30 parts and C solution 3 instead of 10 parts and C solution 50 parts
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 0 part was used.

Example 3 In preparation of the coating liquid for the thermosensitive recording layer of Example 1, B liquid 10
5 parts and B solution C instead of 50 parts and C solution 50 parts
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that parts were used.

Example 4 In the preparation of the liquid C of Example 1, 4-hydroxy-4′-isopropoxydiphenyl sulfone was used instead of Np-toluenesulfonyl-N′-3- (p-toluenesulfonyloxy) phenylurea. Example 1 except that
A thermosensitive recording paper was obtained in the same manner as in (1).

Example 5 In the preparation of the liquid C of Example 1, 4,4'-dihydroxydiphenyl sulfone was used in place of Np-toluenesulfonyl-N'-3- (p-toluenesulfonyloxy) phenylurea. A thermal recording paper was obtained in the same manner as in Example 1 except for the above.

Example 6 In the production of the waste paper pulp of Example 1, a nonionic surfactant (polyoxyethylene nonylphenyl ether) was used.
Was adjusted to obtain a thermal recording paper in which the content ratio of the nonionic surfactant was 6.1 × 10 ⁻² wt% based on the thermal recording paper, in the same manner as in Example 1.

Example 7 In the preparation of the coating liquid for the heat-sensitive recording layer of Example 1, 15 parts of light calcium carbonate having a volume average particle diameter of 1 μm was used instead of 15 parts of aluminum hydroxide having a volume average particle diameter of 1 μm. A thermal recording paper was obtained in the same manner as in Example 1.

Comparative Example 1 In the preparation of the coating liquid for the thermal recording layer of Example 1, B solution 10
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 10 parts of C liquid was used instead of parts.

Comparative Example 2 In the production of the paper support of Example 1, a waste paper pulp concentration of 1
% Slurry (Canada standard freeness 210 ml) 80
Except that 80 parts of LBKP slurry (210 ml of Canadian standard freeness) having a pulp concentration of 1% was used instead of parts.
A thermal recording paper was obtained in the same manner as in Example 1. The content of the nonionic surfactant (polyoxyethylene nonylphenyl ether) in the thermal recording paper was less than 1.0 × 10 ⁻³ .

[Evaluation] The thermal recording paper thus obtained was evaluated as follows, and the results are shown in [Table 1].

(Recording Sensitivity) Thermal Evaluator (Product Name: TH-
PMD, manufactured by Okura Electric Co., Ltd.) was used to develop color on each thermosensitive recording paper at 0.5 mJ / dot, and the color density of the recorded part and the unrecorded part were Macbeth densitometer [RD-914, Macbeth Co.].
Measured in visual mode.

(Heat-resistant background fog property) Each thermosensitive recording paper colored under the conditions for evaluating color development was allowed to stand at 80 ° C. for 24 hours.
The unrecorded area after standing at 0 ° C. for 1 hour was measured by a visual mode of a Macbeth densitometer.

(Plasticizer resistance) A wrap film (trade name: HiWrap KMA-W, manufactured by Mitsui Chemicals, Inc.) was wound in a triple layer on a polycarbonate pipe (40 mmΦ), and color was developed on the condition for evaluating color development. The heat-sensitive recording layer was placed with the heat-sensitive recording layer side facing up, and a wrap film was further wound around it three times and left at 40 ° C. for 24 hours, and then the recording portion was visually evaluated according to the following evaluation criteria.

[0069] ◎: The recorded part can be clearly read ◯: The recorded portion can be read. Δ: The recorded portion can be read although it is erased. X: The recorded portion cannot be read.

[0070]

[Table 1]

[0071]

As shown in Table 1, the thermosensitive recording paper of the present invention is excellent in recording sensitivity and storability of the recording portion, and has an effect of less resistance to background fogging.

Claims (5)

[Claims] 1. A heat-sensitive recording paper having a heat-sensitive recording layer containing a leuco dye and a colorant on a paper support containing waste paper pulp, wherein 4,4′-bis [(4- Methyl-3-phenoxycarbonylaminophenyl) ureido] diphenyl sulfone is contained. 2. A thermosensitive recording layer containing Np- as a colorant.
The thermal recording paper according to claim 1, which contains toluenesulfonyl-N'-3- (p-toluenesulfonyloxy) phenylurea. 3. N-p-toluenesulfonyl-N 'with respect to 4,4'-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenyl sulfone.
The thermal recording paper according to claim 2, wherein the content of -3- (p-toluenesulfonyloxy) phenylurea is 100 to 500% by weight. 4. The nonionic surfactant in the thermal recording paper is 1.0 × 10 ⁻³ to 1.0 × 10 relative to the thermal recording paper.
The heat-sensitive recording paper according to claim 1, 2 or 3, containing ^-1 % by weight. 5. The heat-sensitive recording paper according to claim 1, wherein the heat-sensitive recording layer contains aluminum hydroxide.