JP2000343833A - Heat sensitive recording sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat sensitive recording sheet having heat resistance of certain degree capable of thermally laminating without decreasing color developing capability even by using a support containing a waste paper pulp. SOLUTION: The heat sensitive recording sheet comprises a support containing waste paper pulp and a compound represented by the formula as an organic developer, wherein X is an oxygen atom or a sulfur atom, R is a nonsubstituted or substituted phenyl group, a naphthyl group, an aralkyl group, a 1-6C lower alkyl group, a 3-6C cycloalkyl group, or 2-6C lower alkenyl group, Z is a 1-6C lower alkyl group or an electron attracting group, and n is an integer of 0 to 4.

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 using a support containing waste paper pulp.

[0002]

2. Description of the Related Art In general, a thermosensitive recording paper is usually prepared by grinding and dispersing a colorless or pale-colored dye precursor and an organic developer such as a phenolic substance into fine particles, and then mixing the two together. A coating liquid obtained by adding a filler, a sensitivity improver, a lubricant, and other auxiliaries is applied to a support such as paper, and is instantaneously heated by a hot pen, a thermal head, a hot stamp, a laser beam, or the like. A color recording record is obtained by the chemical reaction of

[0003] These thermosensitive recording papers are applied to a wide range of fields such as measuring recorders, computer terminal printers, facsimile machines, automatic ticket vending machines, and bar code labels.

[0004] In addition to general high-quality paper, synthetic paper, film, plastic, and the like are known as a support for thermal recording paper. In recent years, waste paper has been recovered from paper from the viewpoint of resource conservation. It is required to use as a raw material. JP-A-58-25986 discloses a thermosensitive recording paper in which a thermosensitive recording layer is coated on a paperboard containing waste paper pulp. However, when a support containing waste paper pulp is used for the heat-sensitive recording paper, there arises a problem that the coloring ability is reduced, particularly when stored in a high-temperature and high-humidity environment.

[0005] More recently, as systems for recording on plain paper, such as the electrophotographic system and the ink jet system, have become widespread, there has been an increasing number of opportunities for comparing thermal recording with plain paper recording. For example, the stability of an image is the same as the quality of toner recording, and the stability of a non-recorded portion (blank paper or ground color) before and after recording (hereinafter referred to as ground color stability) is the same as that of plain paper recording. It is required that the temperature be close to 100 ° C. In addition, the use of heat-sensitive recording paper as a food label to be sterilized at a high temperature, and the use of heat lamination for use in cards such as lift tickets, etc. There is an increasing demand for ground color stability against the above heat.

With respect to the stability of ground color to heat, Japanese Patent Application Laid-Open No. 4-353490 discloses 3-dibutylamino-7-
(O-chloroanilino) fluoran, a 4-hydroxydiphenylsulfone compound having a melting point of 120 ° C. or more, a mixture of sodium salt of 2,2′-methylenebis (4,6-di-tert-butylphenyl) phosphate and magnesium silicate, etc. The heat-sensitive recording paper containing 90
It is disclosed that the ground color portion and the recorded image portion have excellent stability even in a high-temperature environment of about ° C.

[0007] The thermal stability of the background color of the heat-sensitive recording paper disclosed in JP-A-4-353490 (hereinafter referred to as "thermal stability") is measured after the substrate is treated in a hot-air dryer at 95 ° C for 5 hours. Although the color has a Macbeth concentration of 0.11, and exhibits considerable thermal stability, it is still insufficient at heat-resistant temperatures. In addition, the heat resistance of conventional heat-sensitive recording paper using a phenolic color developer as a recording material, the recording surface after heat-sensitive recording,
Or it was not possible to laminate the entire record with film.

[0008]

Therefore, according to the present invention, even if a support containing waste paper pulp is used, the coloring ability of the thermosensitive recording paper does not decrease, and the heat-resistant recording paper has a certain degree of heat resistance so that it can be thermally laminated. It is an object to provide a thermal recording paper.

[0009]

The object of the present invention is to provide a thermosensitive recording paper having a thermosensitive recording layer comprising a colorless or pale color dye precursor and an organic developer as main components on a support. This has been achieved by containing waste paper pulp and containing the compound represented by the following general formula (I) in the organic developer.

[0010]

Embedded image (Wherein, X represents an oxygen atom or a sulfur atom, and R is
Unsubstituted or substituted phenyl group, naphthyl group, aralkyl group, lower alkyl group having 1 to 6 carbon atoms, 3 carbon atoms
Represents a cycloalkyl group having 6 to 6 carbon atoms or a lower alkenyl group having 2 to 6 carbon atoms. Z represents a lower alkyl group having 1 to 6 carbon atoms or an electron withdrawing group. n represents the integer of 0-4. )

[0011] The reason why the color developing ability is reduced when a support containing waste paper pulp is used is not clear, but a surfactant is contained in the waste paper pulp, thereby deactivating the color developer. It is thought to happen. For example, 2,2'-
Bis (4-hydroxyphenyl) propane (BPA)
Is a known developer which has been widely used in the past, but is likely to be inactivated by reacting with a surfactant probably because of its relatively high water solubility. On the other hand, it is presumed that the compound represented by the chemical formula (I) used in the present invention effectively prevents inactivation of the color developer.

A thermosensitive recording paper using the compound represented by the general formula (I) as a developer can be recorded with a thermal head or the like.
Even in a thermal environment of about 0 ° C., it exhibits properties that are unlikely with conventional thermal recording paper, such as little occurrence of ground color.

The urea or thiourea derivative represented by the formula (I) of the present invention undergoes a structural change from the neutral structure represented by the above general formula (I) (keto type structure in the case of urea) to form an acidic structure (urea). In the case of the above, it is considered that the coloring ability is exhibited by changing to the enol type structure). Also, after heating,
In order to stabilize the acidic structure that is considered to exhibit color developing ability, it is sufficient that an aromatic ring having an aminosulfonyl group (—SO 2 NH 2) as shown in the general formula (I) of the present invention exists. . Accordingly, R and Z in the general formula (I)
As long as it does not particularly hinder the color developing ability and stability. Specifically, as R, an unsubstituted or substituted phenyl group, naphthyl group, aralkyl group, Represents a lower alkyl group, a cycloalkyl group having 3 to 6 carbon atoms, or a lower alkenyl group having 2 to 6 carbon atoms. Examples of Z include a lower alkyl group having 1 to 6 carbon atoms or an electron withdrawing group such as fluorine, chlorine, bromine, and nitro.

Specific examples of the compounds represented by the above general formula (I) include the following (A-1) to (A-54),
Alternatively, (B-1) to (B-18) may be mentioned, but the present invention is not limited thereto.

[0015]

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[0016]

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[0017]

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[0018]

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[0019]

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[0020]

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[0021]

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[0022]

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The dye precursor used in the present invention includes:
Although not particularly limited, triphenylmethane-based,
Fluoranes, azaphthalides, fluorenes and the like are preferred, and specific examples thereof are shown below. These dye precursors can 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-bis (p-dimethylaminophenyl) phthalide [also known as malachite] Green lactone] <Fluoran leuco dye> 3-Diethylamino-6-methylfluoran 3-Diethylamino-6-methyl-7-anilinofluoran 3-Diethylamino-6-methyl-7- (o, p-dimethylanilino ) Fluoran 3-diethylamino-6-methyl-7-chlorofluoran 3-diethylamino-6-methyl-7- (m-trifluoromethylanilino) fluoran 3-diethylamino-6-methyl-7- (o-chloroanilino) Fluoran 3-diethylamino-6-methyl- 7- (p-chloroanilino) fluoran 3-diethylamino-6-methyl-7- (o-fluoroanilino) fluoran 3-diethylamino-6-methyl-7- (m-methylanilino) fluoran 3-diethylamino-6-methyl- 7-n-octylanilinofluoran 3-diethylamino-6-methyl-7-n-octylaminofluoran 3-diethylamino-6-methyl-7-benzylanilinofluoran 3-diethylamino-6-methyl-7- Dibenzylanilinofluoran 3-Diethylamino-6-chloro-7-methylfluoran 3-Diethylamino-6-chloro-7-anilinofluoran 3-Diethylamino-6-chloro-7-p-methylanilinofluoran 3-diethylamino-6-ethoxyethyl-7-anilinofluora 3-Diethylamino-7-methylfluorane 3-Diethylamino-7-chlorofluorane 3-Diethylamino-7- (m-trifluoromethylanilino) fluoran 3-Diethylamino-7- (o-chloroanilino) fluoran 3-Diethylamino -7- (p-chloroanilino) fluoran 3-diethylamino-7- (o-fluoroanilino) fluoran 3-diethylamino-benzo [a] fluoran 3-diethylamino-benzo [c] fluoran 3-dibutylamino-6-methyl- Fluoran 3-dibutylamino-6-methyl-7-anilinofluoran 3-dibutylamino-6-methyl-7- (o, p-dimethylanilino) fluoran 3-dibutylamino-6-methyl-7- (o -Chloroanilino) fluoran 3-dibutylamido No-6-methyl-7- (p-chloroanilino) fluoran 3-dibutylamino-6-methyl-7- (o-fluoroanilino) fluoran 3-dibutylamino-6-methyl-7- (m-trifluoromethyl Anilino) Fluoran

3-dibutylamino-6-methyl-chlorofluorane 3-dibutylamino-6-ethoxyethyl-7-anilinofluoran 3-dibutylamino-6-chloro-7-anilinofluoran 3-dibutylamino -6-methyl-7-p-methylanilinofluoran 3-dibutylamino-7- (o-chloroanilino) fluoran 3-dibutylamino-7- (o-fluoroanilino) fluoran 3-di-n-pentylamino -6-methyl-7-anilinofluoran 3-di-n-pentylamino-6-methyl-7- (p-
Chloroanilino) fluorane 3-di-n-pentylamino-7- (m-trifluoromethylanilino) fluoran 3-di-n-pentylamino-6-chloro-7-anilinofluoran 3-di-n-pentyl Amino-7- (p-chloroanilino) fluoran 3-pyrrolidino-6-methyl-7-anilinofluoran 3-piperidino-6-methyl-7-anilinofluoran 3- (N-methyl-N-propylamino) -6-methyl-7-anilinofluoran 3- (N-methyl-N-cyclohexylamino) -6
Methyl-7-anilinofluoran 3- (N-ethyl-N-cyclohexylamino) -6
Methyl-7-anilinofluoran 3- (N-ethyl-N-xylamino) -6-methyl-
7- (p-chloroanilino) fluoran 3- (N-ethyl-p-toluidino) -6-methyl-
7-anilinofluoran 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-isoamylamino) -6-chloro-7-anilino Fluoran 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-isobutylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-ethoxypropylamino) -6
-Methyl-7-anilinofluoran

3-cyclohexylamino-6-chlorofluoran 2- (4-oxahexyl) -3-dimethylamino-6
-Methyl-7-anilinofluoran 2- (4-oxahexyl) -3-diethylamino-6
-Methyl-7-anilinofluoran 2- (4-oxahexyl) -3-dipropylamino-
6-methyl-7-anilinofluoran 2-methyl-6-p- (p-dimethylaminophenyl)
Aminoanilinofluoran 2-methoxy-6-p- (p-dimethylaminophenyl) aminoanilinofluoran 2-chloro-3-methyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran 2 -Chloro-6-p- (p-dimethylaminophenyl)
Aminoanilinofluoran 2-nitro-6-p- (p-diethylaminophenyl)
Aminoanilinofluoran 2-amino-6-p- (p-diethylaminophenyl)
Aminoanilinofluoran 2-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluoran 2-phenyl-6-methyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran 2- Benzyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran 2-hydroxy-6-p- (p-phenylaminophenyl) aminoanilinofluoran 3-methyl-6-p- (p-dimethyl Aminophenyl)
Aminoanilinofluoran 3-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluoran 3-diethylamino-6-p- (p-dibutylaminophenyl) aminoanilinofluoran 2,4-dimethyl- 6-[(4-dimethylamino) anilino] -fluoran

<Fluorene Leuco Dye>3,6,6'-Tris (dimethylamino) spiro [fluorene-9,3'-phthalide] 3,6,6'-Tris (diethylamino) spiro [fluorene-9,3 '-Phthalide] <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-methylindole-3
-Yl) phthalide 3,6-bis (diethylamino) fluoran-γ- (3
'-Nitro) anilinolactam 3,6-bis (diethylamino) fluoran-γ- (4
'-Nitro) anilinolactam 1,1-bis- [2', 2 ', 2 ", 2" -tetrakis- (p-dimethylaminophenyl) -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

Further, as sensitizers, stearic acid amide, palmitic acid amide, methoxycarbonyl-N-stearic acid benzamide, N-benzoylstearic acid amide, N-eicosanoic acid amide, ethylenebisstearic acid amide, behenic acid amide, Methylenebisstearic acid amide, methylolamide, N-methylolstearic acid amide, dibenzyl terephthalate, dimethyl terephthalate, dioctyl terephthalate, benzyl p-benzyloxybenzoate, benzyl 1-hydroxy-2-naphthoate, dibenzyl oxalate, Oxalic acid-di-p-
Methylbenzyl, di-p-chlorobenzyl oxalate,
2-naphthylbenzyl ether, m-terphenyl, p
-Benzyl biphenyl, 4-biphenyl paratolyl 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,
-(4-methoxyphenoxy) -2- (2-methylphenoxy) ethane, p-methylthiophenylbenzyl ether, 1,4-di (phenylthio) butane, p-acetotoluidide, p-acetophenethidide, N-acetoacetyl -P-toluidine, di (β-biphenylethoxy)
Benzene, p-di (vinyloxyethoxy) benzene,
1-isopropylphenyl-2-phenylethane, 1,
2-bis (phenoxymethyl) benzene, p-toluenesulfonamide, o-toluenesulfonamide, di-p
-Tolyl carbonate, phenyl-α-naphthyl carbonate, diphenyl sulfone and the like can be added, but not particularly limited thereto. These sensitizers may be used alone or in combination of two or more.

As image stabilizers, 4,4'-butylidene (6-t-butyl-3-methylphenol),
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 and the like can also be added.

The binder used in the heat-sensitive recording layer in the present invention includes a completely saponified polyvinyl alcohol having a degree of polymerization of 200 to 1900, a partially saponified polyvinyl alcohol, a carboxy-modified polyvinyl alcohol, an amide-modified polyvinyl alcohol, and a sulfonic acid-modified polyvinyl alcohol. , Modified polyvinyl alcohol such as butyral-modified polyvinyl alcohol, cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, acetyl cellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer, polyvinyl chloride, and polyacetic acid. Vinyl, polyacrylamide, polyacrylate, polyvinyl butyral, polystyrene and copolymers thereof, polya De resins, silicone resins, petroleum resins, terpene resins, ketone resins, and coumarone resins. These high-molecular substances can be used by dissolving them in solvents such as water, alcohols, ketones, esters, and hydrocarbons.Also, they can be used in emulsified or paste-like form in water or other media. You can also.

Fillers which can be used in the heat-sensitive recording layer of the present invention include silica, calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc, titanium oxide, zinc oxide, aluminum hydroxide, polystyrene resin, urea-formalin. Examples thereof include resins, styrene-methacrylic acid copolymers, styrene-butadiene copolymers, and inorganic or organic fillers such as hollow plastic pigments.

In the heat-sensitive recording layer, a releasing agent such as a fatty acid metal salt, a lubricant such as a wax, a benzophenone-based or triazole-based ultraviolet absorber, a water-resistant agent such as glyoxal, a dispersant, a defoaming agent, Antioxidants, fluorescent dyes and the like can be used.

The amounts of the organic developer and dye precursor used in the present invention and the types and amounts of other various components are determined according to the required performance and recording suitability, and are not particularly limited. For 1 part of the dye precursor, 1 to 8 parts of an organic developer and 1 to 20 parts of a filler are used, and an appropriate binder is 10 to 25% of the total solid content.

These developers, dyes and materials to be added as needed are pulverized by a pulverizer such as a ball mill, an attritor, a sand grinder or an appropriate emulsifying device to a particle size of several microns or less, and a binder and Various coating materials are added according to the purpose to form a coating liquid.
Examples of the coating method include hand coating, size press coater method, roll coater method, air knife coater method, blade coater method, flow coater method, comma direct method, gravure direct method, gravure reverse method, reverse roll coater method and the like. . After spraying, spraying or dipping, drying may be performed.

Further, an overcoat layer of a polymer substance or the like can be provided on the heat-sensitive recording layer for the purpose of improving the storage stability. In addition, an undercoat layer of a polymer substance or the like containing a filler can be provided below the heat-sensitive recording layer for the purpose of enhancing color development sensitivity.

[0036]

The present invention will be described below with reference to examples.
In the description, parts and% indicate parts by weight and% by weight, respectively. [Examples 1 to 22] In Examples 1 to 22, the compounds (A-1), (A-4) and (A-4) were used as color developers on the heat-sensitive recording paper of the present invention.
(A-6) to (A-8), (A-10), (A-12)
~ (A-15), (A-18) ~ (A-23), (A-
25) to (A-27), (B-1), (B-5), or (B-7), 3-dibutylamino-6-methyl-7- (o, p) as a dye precursor -Dimethylanilino) fluorane (ODB-2). Liquid A (Developer dispersion liquid) Developer 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts Water 11.2 parts Liquid B (Dye dispersion liquid) 3-dibutylamino-6-methyl-7- (o , P-Dimethylanilino) fluoran (ODB-2) 2.0 parts 10% aqueous polyvinyl alcohol solution 4.6 parts Water 2.6 parts Each liquid of the above composition was subjected to an average particle size of 1
Milled to a micron. Subsequently, the dispersion liquid was mixed at the following ratio to obtain a coating liquid. Solution A (developer dispersion) 36.0 parts Solution B (dye precursor dispersion) 9.2 parts Kaolin clay (50% dispersion) 12.0 parts 50 g / m ² of waste paper pulp containing the above coating solution %, NBKP
6.0 g applied on one side of medium paper composed of 15%
/ M < ² >, and the sheet was treated with a super calender so that the smoothness became 200 to 600 seconds to obtain a thermosensitive recording paper.

[Examples 23 to 25] Examples 23 to 25
Is an example using a compound (A-10) as a developer and a dye precursor shown below other than ODB-2 as a dye precursor. (Dye precursor) 3-dibutylamino-6methyl-7-anilinofluoran (ODB) 3- (N-isoamyl-N-ethylamino) -6-methyl-7-anilinofluoran (S-205) 3-Diethylamino-7- (m-trifluoromethylanilino) fluoran (Black-100) Dye precursor dispersions other than ODB-2 (solution C) are each separately subjected to a sand grinder to an average particle diameter of 1 micron. Wet pulverization was carried out until. Liquid C (Dye precursor dispersion other than ODB-2) 2.0 parts of the above dye precursor 4.6 parts of a 10% aqueous polyvinyl alcohol solution 2.6 parts of water Next, the dispersion liquid is mixed at the following ratio to form a coating liquid. And Solution A (Developer [A-10] dispersion) 36.0 parts Solution C (Dye precursor dispersion other than ODB-2) 9.2 parts Kaolin clay (50% dispersion) 12.0 parts The above coating The liquid is 50 g / m ² of waste paper pulp 85%, NBKP
6.0 g applied on one side of medium paper composed of 15%
/ M < ² >, and the sheet was treated with a super calender so that the smoothness became 200 to 600 seconds to obtain a thermosensitive recording paper.

Example 26 In Example 26, compound (A-10) was used as a developer, and ODB-2 was used as a dye precursor.
And S-205. In the same manner as in Examples 1 to 22, a developer dispersion (A) of the compound (A-10) was prepared.
Liquid) and the ODB-2 dispersion liquid (liquid B), and the S-205 dispersion liquid (liquid C) was treated in the same manner as in Examples 23 to 25. Solution A (Developer [A-10] dispersion) 36.0 parts Solution B (Dye precursor [ODB-2] dispersion) 4.6 parts Solution B (Dye precursor [S-205] dispersion) 4.6 parts Kaolin clay (50% dispersion) 12.0 parts 85 g of waste paper pulp of 50 g / m ² , NBKP
6.0 g applied on one side of medium paper composed of 15%
/ M < ² >, and the sheet was treated with a super calender so that the smoothness became 200 to 600 seconds to obtain a thermosensitive recording paper.

Example 27 Example 27 is an example in which compound (A-1) and compound (A-10) were used as a color developer, and ODB-2 was used as a dye precursor. Example 1
22 and the compound (A-1) and the compound (A-1)
The developer dispersion liquid (liquid A) and the ODB-2 dispersion liquid (liquid B) were treated. Liquid A (developer [A-1] dispersion) 18.0 parts Liquid A (developer [A-10] dispersion) 18.0 parts Liquid B (dye precursor [ODB-2] dispersion) 9.2 parts Kaolin clay (50% dispersion) 12.0 parts The above coating solution is 50 g / m ² of 85% waste paper pulp, NBKP
6.0 g applied on one side of medium paper composed of 15%
/ M < ² >, and the sheet was treated with a super calender so that the smoothness became 200 to 600 seconds to obtain a thermosensitive recording paper.

[Comparative Examples 1-4] Table 1 shows the developers of Example 1.
Was used to obtain a heat-sensitive recording paper.

Reference Examples 1 and 2 Thermal recording paper was obtained by using a high-quality paper composed of 80% LBKP and 20% NBKP as a support in Example 1 and Comparative Example 1.

Tables 1 to 6 show the test results of the thermal recording papers obtained in the above Examples, Comparative Examples and Reference Examples.

Note (1) Dynamic color density: Printing was performed at the maximum applied energy by using a printer of a personal word processor Rupo-90FII (manufactured by Toshiba Corporation). The recording density of the recording section was measured with a Macbeth densitometer (RD-914, using an amber filter).

Note (2) Coloring ability: A non-colored thermal paper sample was stored at 40 ° C. and 90% for one week, recorded in the same manner as in (1), measured for density, and evaluated according to the following formula. Was.

## EQU00001 ## Expression 1 Density obtained by (2) / Density obtained by (1) .times.100 = R% The larger the value of R, the higher the color developing ability. Practically, 80% or more is desirable.

Note (3) Thermal stability of ground color: using a gear type aging tester (manufactured by Toyo Seiki Seisaku-sho, Ltd.) at a test temperature of 1
Heat resistance tests were performed at 00 ° C, 120 ° C, and 140 ° C for 30 minutes each. After the heat resistance test, the density of the ground color was measured with a Macbeth densitometer.

Note (4) Thermal lamination test: simple laminating apparatus (MS Pouch H-140, manufactured by Meiko Shokai)
And laminated film (MS Pouch Film MP10)
-6095) was used. Examples 1, 4, 6 to 8, 12, 13, 21 and 21 in which thermal recording was already performed under the conditions described above.
Laminated thermosensitive recording paper having a thermosensitive recording section at a feed rate of 20 mm / sec, with the thermosensitive recording papers of Comparative Examples 23, 26, 27 or Comparative Examples 1, 2, 4 and Reference Examples 1, 2 sandwiched between the laminated films. (Examples 28 to 28)
39, Comparative Examples 6 to 8, Reference Examples 3 and 4). After the heat laminating treatment, the color-developed portion and the ground color portion by the above-described thermal recording were measured with a Macbeth densitometer over a laminated film of the laminated thermal recording paper. The contrast between the color-developed portion and the ground color of the laminated thermosensitive recording medium due to thermal recording was evaluated as follows. ：: There is no or almost no ground color (thermal lamination is possible). ×: There is remarkable ground color.

[0047]

[Table 1]

[0048]

[Table 2]

[0049]

[Table 3]

[0050]

[Table 4]

[0051]

[Table 5]

[0052]

According to the present invention, the problem of a decrease in the color developing ability of a thermal recording paper using a support containing waste paper pulp is solved, and severe temperature conditions under which thermal recording paper could not be used until now. (For example, 90 to 140 ° C.), and a heat-sensitive recording paper that can be thermally laminated by a laminator is provided.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kaoru Hamada, Inventor Kaoru 1-30-6, Kamiochiai, Shinjuku-ku, Tokyo Japan Paper Manufacturing Co., Ltd. (72) Inventor Yoshihide Kimura 1-30-6, Kamiochiai, Shinjuku-ku, Tokyo No. Japan Paper Manufacturing Co., Ltd. Product Development Laboratory F-term (reference) 2H026 BB24 EE03

Claims (1)

[Claims] 1. A thermosensitive recording paper comprising a support and a thermosensitive recording layer mainly composed of a colorless or pale color dye precursor and an organic developer which reacts with the dye as a main component. A thermosensitive recording paper containing pulp and wherein the organic developer is a compound represented by the following general formula (I). Embedded image (Wherein, X represents an oxygen atom or a sulfur atom, and R is
Unsubstituted or substituted phenyl group, naphthyl group, aralkyl group, lower alkyl group having 1 to 6 carbon atoms, 3 carbon atoms
Represents a cycloalkyl group having 6 to 6 carbon atoms or a lower alkenyl group having 2 to 6 carbon atoms. Z represents a lower alkyl group having 1 to 6 carbon atoms or an electron withdrawing group. n represents the integer of 0-4. )