JPH0761131A - Thermal recording body - Google Patents

Abstract

PURPOSE:To obtain a thermal recording body whose recorded information is prevented from becoming known by a third person unless it is washed by water and which has excellent confidentiality by providing at least at a part on a recording layer a coloring layer which is water-soluble and is colored so as to make the recorded information on the recording layer unreadable. CONSTITUTION:A thermal recording body has a recording layer which colors at thermal recording arranged on a support body. In this case, at least on a part of the recording layer, a coloring layer which is water-soluble and is colored so as to make recorded information on the recording layer unreadable is provided. The color of the coloring layer is made to be the same color tone as the coloring of the recording layer. When the recorded information on the recording layer is to be read, the recorded information can be obtained by washing the water-soluble coloring layer with water. Thus, a thermal recording body with which the recorded information is prevented from becoming known by a third person and which has excellent confidentiality is provided. The thermal recording body can be utilized for post cards and lottery tickets besides output of facsimile.

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 in which information recorded by a heat-sensitive recording method is not known to a third party.

[0002]

2. Description of the Related Art Utilizing a color reaction between a color former and a color former,
A heat-sensitive recording material in which a recording image is obtained by reacting both color-developing substances with heat energy from a thermal head is well known. Generally, thermal recording materials are relatively inexpensive, and the recording equipment is compact and easy to maintain.
It is used not only as a recording medium for facsimiles and various computers but also in a wide range of fields.

However, since the thermosensitive recording medium which is generally commercially available is recorded in such a state that the output information can be seen by anyone, it is not suitable for the communication of confidential contents. Therefore, in order to conceal the information output to the thermosensitive recording medium, a method of laminating a base material having a concealing property on the thermosensitive recording layer is disclosed in JP-A-61-248785.
As described in JP-A-2-286391, the preservability of a recorded image may be reduced or fog may be generated on the background portion depending on the type of the adhesive used when the substrates are bonded together. Further, the adhesion between the thermal recording material and the concealing substrate may be incomplete, or curling which is difficult to correct may occur after bonding. Further, the production of these thermal recording bodies requires a step of laminating them using equipment such as a laminator, resulting in high cost.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermosensitive recording medium in which information recorded by the thermosensitive recording system is not known to a third party.

[0005]

The present invention provides a heat-sensitive recording material comprising a support and a recording layer provided on the support, the recording layer being capable of coloring during thermal recording.
A thermosensitive recording medium, characterized in that at least a part of the recording layer is provided with a water-soluble colored layer which makes the recording of the recording layer unreadable.

[0006]

The heat-sensitive recording material of the present invention is characterized in that a colored layer which is water-soluble and which makes the recording of the recording layer unreadable is provided on the heat-sensitive recording layer. For interpretation, the recorded information can be obtained by washing the water-soluble colored layer with water.

Examples of the colored layer include starches such as grain starch, pregelatinized starch, oxidized starch, etherified starch and esterified starch, polyvinyl alcohols having various degrees of saponification, acetoacetyl group-modified and carboxyl group-modified polyvinyl alcohol, Modified polyvinyl alcohol such as silicon modified, acrylic resin,
A color dye or a color pigment may be added to a water-soluble polymer such as a polyolefin resin to color the heat-sensitive recording image unreadable (difficult).

For example, it may be colored in a dark color such as black, or may be colored in the same color tone as the heat-sensitive recording image. When the recording layer is a system using a basic dye and a color former, the same basic dye can be used for coloring.

The coloring layer is applied directly on the heat-sensitive recording layer or through a water-resistant protective layer, for example, by a conventional coating machine, and has a dry weight of 0.5 to 10 g / m ² , preferably 1 to 1 by dry gravity. It is preferable to provide it at about 7 g / m ² . Although this colored layer may be provided on the entire surface of the thermosensitive recording medium,
For example, when the area for recording the address and the like is fixed, the area can be provided excluding that area.

Further, a thermosensitive recording medium containing a thermosensitive recording material in which the coloring layer develops a color tone different from the color tone of the coloring, and which is set so as to develop at a temperature higher than the coloring temperature of the recording layer is a facsimile. It is useful for In this case, for example, the address and the like can be read because the heat-sensitive recording material of the colored layer separates from the recording layer by heating at a high temperature. Confidential information cannot be read if it is heated at a temperature lower than the temperature at which the recording material of the colored layer develops color. Note that the colored layer may be washed with water to obtain information.

Further, the heat-sensitive recording layers may be multi-layered so as to develop different color tones at different color development temperatures, and a coloring layer may be provided so that one of the color development tone becomes unreadable. In this case, for example, it is possible to read that an address or the like is colored in a color different from the color tone of the colored layer by heating to one temperature. Confidential information cannot be read by the colored layer when heated to the other temperature. Note that the colored layer may be washed with water to obtain information. This is also useful for facsimiles and the like.

Of course, when an area for printing non-confidential information such as an address is known in advance, a material that develops a color tone different from the coloring in only the area is provided in the thermosensitive recording layer or the coloring layer. You can also In this case, it is not necessary to provide a difference in color development temperature.

In the heat-sensitive recording material of the present invention, the recording mechanism used in the heat-sensitive recording layer may be one that develops or discolors by heat, for example, a combination of a colorless or light basic dye and a coloring agent, Examples include a combination of a diazonium salt and a coupler, a combination of a transition metal such as iron and a chelate compound, a combination of an aromatic isocyanate compound and an imino compound, and a combination of a colorless or light-colored basic dye and a colorant. Is preferably used because it is excellent in the recording density, the background portion and the storability of the recorded image. Various known compounds can be used as the colorless or light-colored basic dye, and the following are exemplified.

3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylaminophenyl) -6-dimethylamino Phthalide, 3-
Diethylamino-7-dibenzylamino-benzo [a]
Fluoran, 3- (N-ethyl-Np-tolyl) amino-7-N-methylanilinofluorane, 3-diethylamino-7-anilinofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3,6-bis (diethylamino) fluorane-γ-anilinolactam, 3
-Cyclohexylamino-6-chlorofluorane, 3-
Diethylamino-6-methyl-7-chlorofluorane,
3-diethylamino-7-chlorofluorane, 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-chlorophenylamino) fluorane, 3-diethylamino-7-
(O-Fluorophenylamino) fluorane, 3-di (n-butyl) amino-7- (o-fluorophenylamino) fluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilino Fluoran, 3- (N
-Ethyl-p-toluidino) -6-methyl-7- (p-
Toluidino) fluorane, 3- (N-ethyl-N-furfurylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3- (N-methyl) -N-n-propylamino) -6-methyl-7-anilinofluorane, 3,3-
Bis [1- (4-methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-2-yl] -4,5
6,7-Tetrachlorophthalide, 3,3-bis [1-
(4-Methoxyphenyl) -1- (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, 3,3-bis [1,1-bis (4- Pyrrolidinophenyl) ethylene-2-yl] -4,5,
6,7-Tetrabromophthalide, 3-p- (p-anilinoanilino) anilino-6-methyl-7-chlorofluorane, 2,2-bis {4- [6 '-(N-cyclohexyl-N-methyl Amino) -3'-methylspiro [phthalide-3,9'-xanthen-2'-ylamino] phenyl} propane, 3,6, -bis (dimethylamino) fluorene-9-spiro-3 '-(6'-dimethyl) amino)
Examples thereof include phthalide. Of course, it is not limited to these, and two or more kinds may be used in combination as required.

Also, various known colorants are known for use in combination with the above basic dye,
For example, the following are exemplified. Inorganic acidic substances such as activated clay, attapulgite, colloidal silica, aluminum silicate, 4-cumylphenol, hydroquinone monobenzyl ether, 4,4'-isopropylidenediphenol, 4,4'-cyclohexylidenediphenol,
1,1-bis (4-hydroxyphenyl) cyclohexane, 4,4'-dihydroxydiphenyl-2,2-butane, 4,4'-dihydroxydiphenylmethane, 2,2
-Bis (4-hydroxyphenyl) -4-methylpentane, 2,2-bis (4-hydroxyphenyl) heptane, bis (4-hydroxyphenylthioethoxy) methane, 1,5-di (4-hydroxyphenylthio) -3-
Oxapentane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,4-bis [α-methyl-α- (4′-hydroxyphenyl) ethyl] benzene, 1,3-bis [α -Methyl-α- (4'-hydroxyphenyl) ethyl] benzene, 4,4'-dihydroxydiphenyl sulfide, bis (4-hydroxy-3-)
Methylphenyl) sulfine, benzyl 4-hydroxybenzoate, butyl bis (p-hydroxyphenyl) acetate, methyl bis (p-hydroxyphenyl) acetate, (4
-Hydroxyphenylthio) acetic acid-2- (4-hydroxyphenylthio) ethyl ester, di (p-hydroxyphenylthioethyl) ether, N, N'-di-m-chlorophenylthiourea, N- (phenoxyethyl)- Four
-Phenolic compounds such as hydroxyphenylsulfonamide, 4- [3- (p-tolylsulfonyl) propyloxy] salicylic acid, 4- [2- (p-methoxyphenoxy) ethyloxy] salicylic acid, 5- [p- (2- p
-Methoxyphenoxyethoxy) cumyl] salicylic acid,
Aromatic carboxylic acids such as p-chlorobenzoic acid, salts of these aromatic carboxylic acids with polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, nickel, and antipyrine of zinc thiocyanate. Examples include organic acidic substances such as complexes.

In the heat-sensitive recording material of the present invention, the use ratio of the basic dye and the coloring agent contained in the recording layer is as follows.
Although it is not particularly limited, a basic dye 100 is generally used.
10-500 parts by weight, preferably 50-
It is desirable to use about 300 parts by weight of the coloring agent.

In the heat-sensitive recording material of the present invention, a sensitizer can be added to the recording layer according to the purpose. Specific examples of the sensitizer include stearic acid amide and methoxycarbonyl-.
N-stearic acid benzamide, N-benzoylstearic acid amide, N-eicosanoic acid amide, ethylenebistearic acid amide, behenic acid amide, methylenebisstearic acid amide, N-methylolstearic acid amide,
Dibenzyl terephthalate, dimethyl terephthalate, dioctyl terephthalate, benzyl p-benzyloxybenzoate, phenyl 1-hydroxy-2-naphthoate, dibenzyl oxalate, oxalate-di-p-methylbenzyl,
Oxalic acid-di-p-chlorobenzyl, 2-naphthylbenzyl ether, m-terphenyl, p-benzylbiphenyl, tolylbiphenyl ether, di (p-methoxyphenoxyethyl) ether, 1,2-di (3-methylphenoxy). ) Ethane, 1,2-di (phenoxy) 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- (2-methylphenoxy) ethane, p-methylthiophenylbenzyl ether, 1,4-di (phenylthio) butane, p
-Acetotoluidide, p-acetophenetidide, N-acetoacetyl-p-toluidine, di (β-biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1-isopropylphenyl-2-phenylethane, p- Examples include (4-tolyloxy) biphenyl and 5-bis (4-methoxyphenoxy) -3-oxa-hentane. Among these sensitizers, 1,2-di (3-methylphenoxy) ethane, 1,2-di (phenoxy) ethane, 2-naphthylbenzyl ether, dibenzyl oxalate, and oxalic acid-di-p-methyl. Benzyl, oxalic acid-di-p-chlorobenzyl, 2-naphthylbenzyl ether, p- (4-tolyloxy) biphenyl,
5-bis (4-methoxyphenoxy) -3-oxa-hentane is more preferable because it exhibits a particularly excellent sensitizing effect.

The amount of these sensitizers used is not particularly limited, but it is generally desirable to adjust the amount within the range of 4 parts by weight or less relative to 1 part by weight of the color developing agent.

Further, a preservative improving agent may be used in combination for the purpose of further enhancing preservability of a recorded image as long as the effect is not impaired. Specific examples of such a storability improver include, for example, 1,4-diglycidyloxybenzene,
Epoxy compounds such as 4,4'-diglycidyloxydiphenyl sulfone, diglycidyl terephthalate, and bisphenol A type epoxy resin, 2,2'-methylenebis (4
-Methyl-6-tert-butylphenol), 2,2'-
Methylenebis (4-ethyl-6-tert-butylphenol), 2,2'-ethylidenebis (4,6-di-tert-
Butylphenol), 4,4'-thiobis (3-methyl-6-tert-butylphenol), 4,4'-thiobis (2-methyl-6-tert-butylphenol), 4,
4'-butylidene bis (6-tert-butyl-m-cresol), 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,1,
3-tris (2-methyl-4-hydroxy-5-tert-
Butylphenyl) butane, 4,4'-thiobis (3-methylphenol), 4,4'-dihydroxy-3,
3 ', 5,5'-tetrabromodiphenyl sulfone,
4,4'-dihydroxy-3,3 ', 5,5'-tetramethyldiphenyl sulfone, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2-
Hindered phenol compounds such as bis (4-hydroxy-3,5-dichlorophenyl) propane and 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 1- [α-methyl-α- (4 '-Hydroxyphenyl) ethyl] -4- [α', α'-bis (4 "-hydroxyphenyl) ethyl] benzene, N, N'-di-2-
Examples thereof include naphthyl-p-phenylenediamine and 2,2'-methylenebis (4,6-di-tert-butylphenyl) sodium phosphate.

In order to prepare a coating liquid for a recording layer containing these substances, water is generally used as a dispersion medium, and a basic dye, a coloring agent, and further a basic dye, a coloring agent, and the like are required by a stirring / grinding machine such as a ball mill, attritor, or sand mill. A sensitizer or the like added according to the above is dispersed together or separately to prepare a coating liquid.
In the coating liquid, starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, arabic gum as an adhesive,
Carboxy modified polyvinyl alcohol, acetoacetyl group modified polyvinyl alcohol, silicon modified polyvinyl alcohol, fully saponified and partially saponified polyvinyl alcohol, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid Copolymer salts, styrene / acrylic acid copolymer salts, styrene / butadiene copolymer emulsions, etc. are used in an amount of 10 to 40% by weight, preferably about 15 to 30% by weight, based on the total solid content.

It is also possible to use various pigments in combination in the coating liquid, for example, kaolin, clay, calcium carbonate, calcined clay, calcined kaolin, titanium oxide, diatomaceous earth,
Inorganic pigments such as fine particulate anhydrous silica and activated clay, styrene microballs, nylon powder, polyethylene powder, urea / formalin resin filler, and organic pigments such as raw starch particles can be used.

Further, various auxiliaries can be added to the coating liquid, for example, sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate / sodium salt, alginate, fatty acid metal salt and the like. Dispersant, benzophenone type,
Examples thereof include UV absorbers such as triazole type, defoaming agents, fluorescent dyes, and coloring dyes.

When a colored layer is provided on the heat-sensitive recording layer, a hardener such as glyoxal, methylol urea, boric acid, dialdehyde starch, or an epoxy compound is added to the recording layer to enhance water resistance. Good.

The protective layer provided on the heat-sensitive recording layer is, for example, polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, starch and derivatives thereof. , Casein, sodium alginate, polyvinylpyrrolidone, polyacrylamide, styrene / maleic acid copolymer, polyurethane resin, urea resin, melamine resin, polyamide resin, epoxy modified polyamide resin, styrene / butadiene emulsion, styrene / acrylate emulsion Glyoxal, methylolurea, boric acid, diacetic acid to improve water resistance in adhesives such as acrylic ester emulsions. Dehydrogenase starch, adding a curing agent such as an epoxy compound, a pigment and if necessary, ultraviolet absorbers include those obtained by adding an antifoaming agent or the like. Also,
A layer cured by using an electron beam curable resin or an ultraviolet curable resin is also preferable because it has excellent water resistance.

In the present invention, the method for forming the thermosensitive recording layer, the protective layer and the colored layer is not particularly limited,
It can be formed according to well-known and conventional techniques,
For example, it can be formed by a method of coating and drying the coating liquid on a support by air knife coating, varibar blade coating, pure blade coating, short dwell coating, curtain coating, or the like.

As the support, an opaque support such as paper, synthetic paper, non-woven fabric, and plastic film is appropriately selected and used. It is also possible to color the support, print a tint block or the like to increase the hiding property or opacity, or laminate a plastic film or the like to increase the water resistance.

If necessary, a resin layer may be provided on the back side of the recording medium, an undercoat layer may be provided between the support and the thermosensitive recording layer to improve image quality and sensitivity, and the back side of the recording medium may be treated with an adhesive. It is possible to add various publicly known techniques in the field of heat-sensitive recording material manufacturing, such as applying an adhesive label to form an adhesive label or providing a magnetic layer on the back surface of the recording material. Further, the image quality and the image density can be improved by performing a super calendering process after forming each layer.

When the thermosensitive recording medium of the present invention is used as a slip or receipt, characters or symbols are put on the support by watermarking or embossing, or the base paper or any of the layers is coated with a foam. It is also possible to print the anti-counterfeiting characters and symbols, the tint block, the advertisement, and the description. Further, the same constitution of the recording medium may be provided on the back side to form a double-sided thermal recording medium.

[0029]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In addition, "part" and "%" in an example show "weight part" and "weight%", respectively, unless there is particular notice.

Example 1 (Preparation of solution A) 3- (N-ethyl-N-isoamylamino) -6-methyl-7-phenylaminofluorane 10
Part, 1,2-bis (3-methylphenoxy) ethane 20
Parts, 15 parts of a 5% aqueous solution of methyl cellulose, and 30 parts of water were pulverized with a sand grinder until the average particle size became 1 μm.

(Preparation of solution B) 4,4'-isopropylidenediphenol 20 parts, methylcellulose 5% aqueous solution 10
And 20 parts of water with a sand grinder so that the average particle size is 1.
It was pulverized to a size of 5 μm.

(Formation of thermosensitive recording layer) 50 parts of solution A, 5 parts of solution B
0 parts, 15% polyvinyl alcohol aqueous solution (trade name: P
VA-105, manufactured by Kuraray Co., Ltd., 60 parts, vinyl chloride emulsion (trade name: Vinyl Brand 200C, manufactured by Nissin Chemical Industry Co., Ltd.) 20% 45% aqueous dispersion, fine anhydrous silica (trade name: Mizuka Seal P-527) , Mizusawa Chemical Co., Ltd.) 1
0 part and 10 parts of water were mixed and stirred to prepare a coating liquid for the heat-sensitive recording layer. A 100 μm thick transparent polyethylene phthalate film (trade name: ester film A-7) was applied to this coating liquid.
300, manufactured by Toyobo Co., Ltd.) with a wire bar so that the dry weight will be 5 g / m ^2, and then 6 with a dryer at 45 ° C.
It was dried for 0 seconds to form a thermosensitive recording layer.

(Formation of Protective Layer) On the above heat-sensitive recording layer,
The coating amount after drying a coating liquid having the following composition is 3 g / m. ²
Was coated and dried so that a protective layer was provided. Coating liquid for protective layer: acetoacetyl-modified polyvinyl alcohol
10 (trade name: Z-200, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
% Aqueous solution 200 parts, aluminum hydroxide 100 parts, methyl
Roll urea 5% aqueous solution 10 parts.

(Preparation of solution C) 3- (N
-Ethyl-N-isoamylamino) -6-methyl-7-
After adding and dissolving 5 parts of phenylaminofluorane and 5 parts of 4,4'-isopropylidenediphenol, toluene was distilled off under reduced pressure to obtain a black reaction product. Then, the above blue reaction product was added to 100 parts of water and the average particle size was adjusted to 1.5 with a sand mill.
It was pulverized until it became μm.

(Formation of Colored Layer) A thermosensitive recording medium having a colored layer is formed by coating and drying a coating liquid having the following composition on the protective layer so that the coating amount after drying is 5 g / m ^2. Got Coating liquid for colored layer: 8 parts of C liquid, 40 parts of 10% aqueous solution of acetoacetyl-modified polyvinyl alcohol (trade name: Z-200, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), 30% of zinc stearate
2 parts water dispersion, 10 parts water.

When the obtained thermal recording material was recorded using a thermal facsimile (Panafax UF-6), the recorded information was unreadable. Next, when the recording surface of the recording medium was lightly rubbed with a sponge 5 times in water having a water temperature of 25 ° C. and washed with water, recorded information appeared.

[0037]

As described above, the heat-sensitive recording material of the present invention has extremely excellent heat-sensitive recording properties such that the heat-recorded confidential information cannot be read and the information can be obtained by washing with water. And, of course, the output of Fakurimiri,
It can be applied to items such as postcards as well as those that have confidentiality.

Claims (2)

[Claims] 1. A thermosensitive recording medium comprising a support and a recording layer which develops color during thermal recording, wherein at least a part of the recording layer is water-soluble and the recording of the recording layer is colored unreadable. A thermosensitive recording medium having a layer. 2. The thermosensitive recording medium according to claim 1, wherein the coloring has the same color tone as that of the color of the recording layer.