JPH07164754A - Thermal recording material - Google Patents

Abstract

PURPOSE:To reduce a blocking phenomenon and enhance the whitenesses of the background parts of both surfaces of the support to the same degree. CONSTITUTION:A thermal recording material is constituted by providing a thermal color forming layer based on an electron donating colorless or light- colored dye precursor and an electron acceptive coupler on a support and, by heating this thermal recording material by a thermal head, a hot pen or laser beam, the dye precursor and the coupler are instantaneously reacted to form a recording image. In this thermal recording material wherein the thermal color forming layers are provided on both surfaces of the support, a fluorescent brigthtener is added to the respective thermal color forming layers. A protective layer is provided to the outside of at least one of the thermal color forming layers. As the fluorescent brightener, a diaminostylbenzyl derivative, an imidazole derivative, a cumarin derivative, a tiriazole derivative or a carbazol derivative are designated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material having heat-sensitive coloring layers provided on both sides of a support. More specifically, the whiteness of the background portions on both sides is about the same and the reliability of the background portion is high. To a heat-sensitive recording material excellent in

[0002]

2. Description of the Related Art A heat-sensitive recording material comprises a support and a heat-sensitive coloring layer containing an electron-donating colorless or light-colored dye precursor and an electron-accepting developer as main components. By heating with a head, a hot pen, a laser beam or the like, the dye precursor and the developer react instantaneously to obtain a recorded image. Since such a heat-sensitive recording material has the advantages that a recorded image can be obtained by a relatively simple device, maintenance is easy, and that noise is reduced, it can be used in the fields of facsimiles, labels, printers, and ticket vending machines. Widely used as a material.

In recent years, the use of paper has significantly increased due to the progress of office equipment such as word processors and the widespread use of computers. On the other hand, due to the recent progress in the destruction of the global environment, environmental protection has become more important, and the conservation and recycling of timber resources are encouraged in order to prevent excessive deforestation.

By the way, most of the conventional heat-sensitive recording materials are coated with a heat-sensitive coloring layer on only one side, which is uneconomical from the viewpoint of saving the above-mentioned wood resources. As an improvement thereof, Japanese Utility Model Publication No. 58-69462. , Jitsukai Sho 58-19406
No. 6 discloses a technique of providing a thermosensitive coloring layer on both surfaces of a support. Further, recently, there has been a demand for development of a double-sided heat-sensitive recording material for use in word processor papers, tickets, slips, cards and the like. However, a heat-sensitive recording material having a coating layer on both sides is more apt to cause a phenomenon called blocking in which the front surface and the back surface are attached to each other, as compared with a recording layer having a coating layer on only one surface, and thus has a disadvantage of poor workability. Also, a thermal recording material that can be printed on both sides does not require distinction between the front and back, unlike one that can record on only one side, and the whiteness of the background part on the front and back sides is the same. It is desirable because it has excellent properties and can have plain paper properties.

However, in the heat-sensitive recording materials that have hitherto been proposed, measures for preventing blocking are insufficient, and since different heat-sensitive coloring layers are provided on the front surface and the back surface, the white on the front surface and the back surface are white. The fact is that no one with the same value has been obtained.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the circumstances of the prior art as described above, and in a heat-sensitive recording material having a heat-sensitive recording layer on both sides of a support, a blocking phenomenon is small, Moreover, it is an object of the present invention to provide a heat-sensitive recording material in which the whiteness of the background portion of the front surface is as high as that of the back surface. Another object of the present invention is to provide a heat-sensitive recording material having excellent reliability of the background portion.

[0007]

In order to solve the above-mentioned problems, the present invention provides a thermosensitive recording material having a thermosensitive coloring layer on both sides of a support, wherein each thermosensitive coloring layer contains a fluorescent whitening agent. A heat-sensitive recording material is provided. In the present invention, it is preferable to provide a protective layer on the outside of at least one of the thermosensitive coloring layers.

In the present invention, as the fluorescent whitening agent,
For example, a diaminostilbenzyl derivative, an imidazole derivative, a coumarin derivative, a triazole derivative, a carbazole derivative, a pyridine derivative, a naphthalic acid derivative, an imidazolone derivative and the like can be used, but the invention is not limited thereto.

In the present invention, the leuco dyes used in the thermosensitive coloring layer may be used alone or in admixture of two or more.
As such leuco dyes, those applied to this type of heat-sensitive material are arbitrarily applied, for example, triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, indolinophtalide-based, etc. Leuco compounds of dyes are preferably used. Specific examples of such leuco dyes include those shown below.

3,3-bis (p-dimethylaminophenyl)-
Phthalide, 3,3-bis (p-dimethylaminophenyl) -6
-Dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis (p-dimethylaminophenyl)
-6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis (p-
Dibutylaminophenyl) phthalide, 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5,
7-Dimethylfluorane, 3-N-methyl-N-isobutyl-6-
Methyl-7-anilinofluorane, 3-N-ethyl-N-isoamyl-6-methyl-7-anilinofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3- (Np-tolyl-N-ethylamino) -6-
Methyl-7-anilinofluorane, 3-pyrrolidino-6-
Methyl-7-anilinofluorane, 2- {N- (3'-trifluoromethylphenyl) amino} -6-diethylaminofluorane, 2- {3,6-bis (diethylamino) -9- (o-
Chloranilino) xanthylbenzoic acid lactam}, 3-diethylamino-6-methyl-7- (m-trichloromethylanilino) fluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3-dibutylamino-7- (o -Chloranilino) fluorane, 3-N-methyl-N-amylamino-6-methyl-7-anilinofluorane, 3-N-methyl-N
-Cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (2 ', 4'-dimethylanilino ) Fluoran, 3- (N, N-diethylamino) -5
-Methyl-7- (N, N-dibenzylamino) fluorane, benzoyl leuco methylene blue, 6'-chloro-8'-methoxy-benzoindolino-spiropyran, 6'-bromo-
3'-methoxy-benzoindolino-spiropyran, 3-
(2'-hydroxy-4'-dimethylaminophenyl) -3-
(2'-methoxy-5'-chlorophenyl) phthalide, 3- (2 '
-Hydroxy-4'-dimethylaminophenyl) -3- (2 '
-Methoxy-5'-nitrophenyl) phthalide, 3- (2'-
Hydroxy-4'-diethylaminophenyl) -3- (2'-
Methoxy-5'-methylphenyl) phthalide, 3- (2'-methoxy-4'-dimethylaminophenyl) -3- (2'-hydroxy-4'-chloro-5'-methylphenyl) phthalide, 3
-Morpholino-7- (N-propyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7- (N-benzyl-trifluoromethyl) Anilino) fluorane, 3-pyrrolidino-7- (di-p-chlorophenyl)
Methylaminofluorane, 3-diethylamino-5-chloro-
7- (α-phenylethylamino) fluorane, 3- (N-ethyl
-p-toluidino) -7- (α-phenylethylamino) fluorane, 3-diethylamino-7- (o-methoxycarbonylphenylamino) fluorane, 3-diethylamino-5-methyl-7-
(α-Phenylethylamino) fluorane, 3-diethylamino-7-piperidinofluorane, 2-chloro-3- (N-methyltoluidino) -7- (pn-butylanilino) fluorane, 3-
(N-methyl-N-isopropylamino) -6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3,6-bis (dimethylamino) fluorene spiro ( 9,3 ')-6'-Dimethylaminophthalide, 3- (N-benzyl-N-cyclohexylamino) -5,6-benzo-7-α
-Naphthylamino-4'-bromofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-N-ethyl-N
-(2-Ethoxypropyl) amino-6-methyl-7-anilinofluorane, 3-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-7-anilinofluorane, 3-diethylamino
-6-methyl-7-mesitidino-4 ', 5'-benzofluorane, 3-
(p-Dimethylaminophenyl) -3- {1,1-bis (p-dimethylaminophenyl) ethylene-2-yl} phthalide, 3- (p-dimethylaminophenyl) -3- {1,1-bis ( p-dimethylaminophenyl) ethylene-2-yl} -6-dimethylaminophthalide,
3- (p-dimethylaminophenyl) -3- (1-p-dimethylaminophenyl-1-phenylethylene-2-yl) phthalide, 3- (p-
Dimethylaminophenyl) -3- (1-p-dimethylaminophenyl-1-p-chlorophenylethylene-2-yl) -6-dimethylaminophthalide, 3- (4'-dimethylamino-2'-methoxy)-
3- (1 ''-p-dimethylaminophenyl-1 ''-p-chlorophenyl-1 '', 3 ''-butadiene-4 ''-yl) benzophthalide, 3-
(4'-Dimethylamino-2'-benzyloxy) -3- (1 ''-p-dimethylaminophenyl-1 ''-phenyl-1 '', 3 ''-butadiene-4 ''-yl) benzophthalide , 3-dimethylamino-6-dimethylamino-fluorene-9-spiro 3 '(6'-dimethylamino) phthalide, 3,3-bis {2- (p-dimethylaminophenyl) -2- (p-methoxyphenyl ) Ethenyl} -4,5,6,7-tetrachlorophthalide, 3-bis {1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl} -5,6-dichloro-4,7- Dibromophthalide, bis (p-dimethylaminostyryl) -1-naphthalenesulfonylmethane, bis (p-dimethylaminostyryl) -1
-p-tolylsulfonylmethane and the like.

As the color developer used in the thermosensitive color developing layer of the present invention, various electron-accepting compounds which develop the above leuco dye upon contact, such as phenolic compounds, thiophenolic compounds, thiourea derivatives, organic compounds Acids and metal salts thereof are preferably applied, and specific examples thereof include those shown below.

4,4'-isopropylidene bisphenol,
4,4'-isopropylidene bis (o-methylphenol),
4,4'-secondary butylidene bisphenol 4,4'-isopropylidene bis (2-tert-butylphenol), 4,4'-cyclohexylidene diphenol,
4,4'-isopropylidene bis (2-chlorophenol),
2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 4,4'-butylidenebis
(6-tert-butyl-2-methylphenol), 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 ( 6-tert-butyl-2-methylphenol),
4,4'-diphenol sulfone, 4-isopropoxy-4'-hydroxydiphenyl sulfone, 4-benzyloxy-4'-hydroxydiphenyl sulfone, 4,4'-diphenol sulfoxide, P-hydroxybenzoic acid isopropyl, P -Benzyl hydroxybenzoate, benzyl protocatechuate, stearyl gallate, lauryl gallate, octyl gallate, 1,7-bis (4-hydroxyphenylthio) -3,
5-dioxaheptane, 1,5-bis (4-hydroxyphenylthio) -3-oxapentane, 1,3-bis (4-hydroxyphenylthio) -propane, 1,3-bis (4-hydroxyphenylthio) ) -2-Hydroxypropane, N, N'-diphenylthiourea, N, N'-di (m-chlorophenyl) thiourea, salicylanilide, 5-chloro-salicylanilide, 2-hydroxy-3-naphthoic acid, 2 -Hydroxy-1
-Naphthoic acid, 1-hydroxy-2-naphthoic acid, metal salts of hydroxynaphthoic acid such as zinc, aluminum and calcium, bis- (4-hydroxyphenyl) acetic acid methyl ester, bis- (4-hydroxyphenyl) acetic acid benzyl ester , 1,3-bis (4-hydroxycumyl) benzene, 1,4
-Bis (4-hydroxycumyl) benzene, 2,4'-diphenol sulfone, 3,3'-diallyl-4,4'-diphenol sulfone, α, α-bis (4-hydroxyphenyl) -α- Methyltoluene, zinc thiocyanate antipyrine complex,
Tetrabromobisphenol A, tetrabromobisphenol S, 4,4'-thiobis (2-methylphenol), 4,4'-
Thiobis (2-chlorophenol) etc.

In order to produce the heat-sensitive recording material of the present invention,
When the leuco dye and the color developer are bound and supported on the support, various commonly used binders can be appropriately used, and specific examples thereof include the following.

Polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose and ethyl cellulose, polyacrylic acid sodium -Da, polyvinylpyrrolidone, acrylamide / acrylic acid ester copolymer, acrylamide / acrylic acid ester / methacrylic acid terpolymer, styrene /
Maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, soda alginate, gelatin, other water-soluble polymers such as casein, polyvinyl acetate, polyurethane, polyacrylic acid, Polyacrylic acid ester, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene /
Emulsion such as vinyl acetate copolymer, latex such as styrene / butadiene copolymer and styrene / butadiene / acrylic copolymer.

Further, in the present invention, various heat fusible substances can be used as the sensitivity improving agent, and specific examples thereof include the followings, but the present invention is not limited thereto. . Fatty acids such as stearic acid and behenic acid, fatty acid amides such as stearic acid amide and palmitic acid amide, fatty acid metal salts such as zinc stearate, aluminum stearate, calcium stearate, zinc palmitate and zinc behenate, p-benzyl Biphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, phenyl β-naphthoate, phenyl 1-hydroxy-2-naphthoate, methyl 1-hydroxy-2-naphthoate, diphenyl Carbonate, Greacol Carbonate, Dibenzyl terephthalate, Dimethyl terephthalate, 1,4-Dimethoxynaphthalene, 1,4-Diethoxynaphthalene, 1,4-Dibenzyloxynaphthalene, 1,2-Diphenoxyethane, 1,2 -
Bis (3-methylphenoxy) ethane, 1,2-bis (4-methylphenoxy) ethane, 1,4-diphenoxy-2-butene, 1,2-
Bis (4-methoxyphenylthio) ethane, dibenzoylmethane, 1,4-diphenylthiobutane, 1,4-diphenylthio
-2-butene, 1,3-bis (2-vinyloxyethoxy) benzene, 1,4-bis (2-vinyloxyethoxy) benzene, p- (2
-Vinyloxyethoxy) bifer, p-aryloxypphenyl, p-propargyloxybiphenyl, dibenzoyloxymethane, dibenzoyloxypropane, dibenzyl disulfide, 1,1-diphenylethanol, 1,1-diphenylpropanol, p -Benzyloxybenzyl alcohol, 1,3-phenoxy-2-propanol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene, N-
Octadecylcarbamoylbenzene, 1,2-bis (4-methoxyphenoxy) propane, 1,5-bis (4-methoxyphenoxy) -3-oxapentane, dibenzyl oxalate, bis (4-methylbenzyl) oxalate, oxalic acid Bis (4-chlorobenzyl) and the like.

Further, as the protective layer of the present invention, a binder,
Materials such as pigments are used. As the binder, various conventional binders can be used in appropriate amounts, and specific examples thereof include the following. Polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylic ester copolymer, acrylamide / acrylic ester / methacrylic Acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, water-soluble polymer such as polyacrylamide, sodium alginate, gelatin, casein, and polyvinyl acetate ,
Emulsion of polyurethane, polyacrylic acid ester, polymethacrylic acid ester, vinyl chloride / vinyl acetate copolymer, ethylene / vinyl acetate copolymer and the like, latex of styrene / butadiene / acrylic copolymer and the like.

As the pigment, inorganic pigments and organic pigments may be used alone or in combination of two or more. As the inorganic pigment, an oil supply amount of 30 ml / 100 g or more, preferably 80 ml / 100 g or more is selected. These inorganic pigments can be selected from pigments commonly used in this type of heat-sensitive recording material, and examples thereof include calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate and clay. Inorganic pigments such as talc, surface-treated calcium and silica, kaolin, calcined kaolin, and colloidal silica can be used. As the organic pigment, for example, urea-formalin resin, styrene / methacrylic acid copolymer, polystyrene resin, vinylidene chloride resin, etc. can be used. Further, if necessary, a lubricant may be contained, and examples of the lubricant include higher fatty acids such as zinc stearate and metal salts thereof, higher fatty acid amides, higher fatty acid esters, animal-based, vegetable-based, mineral-based or petroleum-based oils. Various waxes, etc. can be used.

In the case of obtaining a tube heat recording material according to the present invention, a leuco dye, a developer, the compound of the present invention and, if necessary, an additive material commonly used in this kind of tube heat recording material, for example, a filler, A surfactant, a lubricant, a pressure color-developing inhibitor, etc. can be used in combination. In this case, as a filler, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, kaolin, talc, other inorganic fine powder such as surface-treated calcium or silica, Urea-formalin resin, styrene / methacrylic acid copolymer, polystyrene resin, vinylidene chloride resin, or other organic fine powder can be used.
As the lubricant, higher fatty acids and metal salts thereof, higher fatty acid amides, higher fatty acid esters, various waxes of animal, vegetable, mineral or petroleum type can be used.

Further, in the present invention, an intermediate layer may be provided between the support and the thermosensitive coloring layer, if necessary. In this case, as the component constituting the intermediate layer, the above-mentioned pigment, binder, heat-fusible substance and the like can be used, and in addition hollow particles can be contained. Various kinds of hollow body fine particles are used, and specific examples thereof include hollow body fine particles formed of a material such as glass, ceramics, and plastics. Particularly, the hollow body fine particles made of a thermoplastic resin having a hollow ratio of 10% or more are used. Hollow body particles are preferred.

[0020]

The heat-sensitive recording material of the present invention has substantially the same degree of whiteness of the background portion on the front surface and the back surface, is excellent in the reliability of the background portion, and is free from blocking.

[0021]

EXAMPLES Next, the present invention will be described in more detail by way of examples. All parts and% shown below are based on weight.

Example 1 [Solution A] 3-dibutylamino-6-methyl-7-anilinofluorane 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts water 60 parts [Solution B] 4-isopropoxy-4'- Hydroxydiphenyl sulfone 10 parts Polyvinyl alcohol 10% aqueous solution 25 parts Calcium carbonate 15 parts Water 50 parts [C liquid] 1,1,3-tris (2-methyl-4-hydroxy-5-siku 20 parts Rohexylphenyl) butane 10% aqueous solution of polyvinyl alcohol 20 parts water 60 parts

The mixture consisting of the above composition was dispersed using a sand mill so that the average particle diameters were 1.5 μm or more and 2.5 μm or less, respectively, to obtain [solution A], [solution B] and [solution C]. It was adjusted.

[Liquid D] Micro hollow particle dispersion (copolymer resin mainly composed of styrene-acryl 36 parts) (solid content concentration 27.5%, average particle diameter 1 μm, hollow ratio 50%) styrene / butadiene copolymer Polymerized latex 10 parts (solid content concentration 47.5%) [C liquid] 25 parts water 29 parts

A mixture having the above composition was stirred and dispersed to prepare an intermediate layer-forming liquid, which was prepared with a commercially available high-quality paper (basis weight: 52 g).
/ M ² ), both sides of which were dried to give a weight of 5 g / m ² and dried to obtain an intermediate-layer coated paper.

Next, 10 parts of [solution A] and [solution B] 60
Part and Chukyo Yushi's zinc stearate dispersion (trade name: Hydrin Z730 concentration 30%) 20 parts and Sumitomo Chemical's (4,4'-diaminostilbene disulfonic acid derivative (trade name Whitex BB) 1 part are mixed to produce a thermosensitive color. This was used as a layer solution, and this was coated on both sides of the above-mentioned intermediate layer coated paper so as to have a weight of 7 g / m ² and dried to obtain an intermediate layer / thermosensitive coloring layer coated paper. Thirty
A double-sided heat-sensitive recording material of the present invention was obtained by calendering for 0 to 1500 seconds.

Example 2 [Solution E] 10% aqueous solution of polyvinyl alcohol modified with itaconic acid 50 parts 15% aqueous solution of polyamide epichlorohydrin 10 parts Aluminum hydroxide (average particle size 3 μm) 4 parts Zinc stearate 0.5 parts Water 30 parts

The mixture having the above composition was well stirred to give a protective layer liquid, which was dried on both sides of the intermediate layer / thermosensitive color developing layer-coated paper in a weight of 2 g / d. After being coated and dried so as to have a surface area of m ² , it was calendered so that the smoothness of both surfaces was 300 to 1500 seconds, respectively, to obtain a double-sided heat-sensitive recording material of the present invention.

Example 3 Sumitomo Chemical's 4,4'-diaminostilbene disulfonic acid derivative (trade name: White in the thermosensitive color developing solution of Example 1)
x BB), a double-sided heat-sensitive recording material was obtained in the same manner as in Example 1 except that a coumarin derivative manufactured by Sumitomo Chemical Co., Ltd. (trade name: Whitefluor PVB) was used.

Comparative Example 1 As a thermosensitive color developing layer liquid on one side of the intermediate layer coated paper of Example 1, the thermosensitive color developing layer liquid of Example 1 was used to prepare a 4,4'-diaminostilbene disulfonic acid derivative (trade name: White) manufactured by Sumitomo Chemical.
x BB) was applied and dried in the same manner as in Example 1 to obtain a heat-sensitive recording material of Comparative Example.

The four types of double-sided heat-sensitive recording materials thus obtained were subjected to a light resistance test of 5000 Lux and 100 hr, the appearance and whiteness of blank paper were visually observed and measured before and after the test, and the results are summarized in Table 1. .

[0032]

[Table 1] {Blank paper appearance} The double-sided thermosensitive recording material is displayed in the color tone when visually observed. {Whiteness} Toyo Seiki Digital Hunter Whiteness Meter T
It was measured by YPE D. {Blocking property} Left at 40 ° C. and 90% RH for 24 hours Pressurization: 500 g / cm ² ○: No blocking ×: Blocking

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiro Uchimura 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (2)

[Claims] 1. A thermosensitive recording material having thermosensitive coloring layers on both sides of a support, wherein each thermosensitive coloring layer contains a fluorescent whitening agent. 2. The thermosensitive recording material according to claim 1, wherein a protective layer is provided on the outside of at least one of the thermosensitive coloring layers.