JPS61169278A - Two-color thermal recording material - Google Patents

Abstract

PURPOSE:To enhance color separation properties and prevent colors from being mixed with each other, by a construction wherein a thermal color forming layer constituting an upper layer is constituted of a color forming system comprising a basic leuco dye and a color developer, and a specified piperadine derivative is used as a decoloring agent for the color forming system. CONSTITUTION:The first and second thermal color forming layers requiring different quantities of thermal energy for color forming and capable of forming color with different hues are laminated on a base, with the layer requiring less thermal energy provided as the upper layer, to produce a two-color thermal recording material. A piperadine derivative of formula I, II or III, wherein each of R1 and R2 is alkyl, cycloalkyl, aryl or aralkyl, X is carbonyl or sulfonyl, R is lower alkyl, and n is an integer of 0-2, is used as a decoloring agent for the color forming system of the second color forming layer.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a two-color heat-sensitive recording material, and more specifically, the present invention relates to a two-color heat-sensitive recording material, and more specifically, a two-color heat-sensitive recording material in which heat-sensitive color-forming layers each having different color-forming heat energies and producing different tones are sequentially stacked on a support. This invention relates to a two-color thermosensitive recording material formed.

[Prior art]

A thermosensitive recording material is a material in which a thermosensitive coloring layer capable of forming a colored image by heating is provided on a support such as paper, and a thermal printer equipped with a thermal head is widely used for heating.

These conventional heat-sensitive recording materials include a colorless or light-colored leuco dye (color-forming main agent) having a lactone ring, lactam ring, spiropyran ring, etc. in the heat-sensitive coloring layer, and a color developer that develops color by reacting with this leuco dye when heated. color development aid)
Those containing these are widely used because they have clear color tones and less fogging.

By the way, heat-sensitive recording materials can easily produce colored images just by heating them, so they are not only used for copying books, documents, etc., but are also used in various fields such as computer, facsimile, telex, and other fields for recording various types of information and measuring equipment. It is used in In recent years, applications for two-color heat-sensitive recording materials have been expanding, including labels, tickets, coupons, tack paper,
It has also been used for video printers, etc. Conventionally, most thermal recordings have been monochromatic, black or blue, except for those for recorders, but depending on the purpose of the recording, it would naturally be desirable if parts could be colored in different colors. This is a major market need.

Attempts have been made to obtain two-color recording, and various methods and materials have been proposed.

Multi-color thermosensitive recording paper is generally formed by layering two types of high-temperature and low-temperature coloring layers that develop different tones with different coloring heat energies on a support. It can be divided into two types.

One is to mix the color tone of the low-temperature coloring layer when coloring the high-temperature coloring layer to obtain a color tone different from that of the low-temperature coloring layer, and the other is to color the high-temperature coloring layer. In this case, by using a color erasing agent that erases the color of the low-temperature color-forming layer, only the color tone of the high-temperature color-forming layer is obtained without color mixture of the color tone of the low-temperature color-forming layer.

As a specific example of these, the former is
Publication No. 9, Special Publication No. 49-4342, Special Publication No. 49-27
708, JP-A-48-86543, JP-A-49-65239, etc., and the latter is described in JP-A-5-17865 and JP-A-50-17.
These are disclosed in Japanese Patent Publication No. 866, Japanese Patent Publication No. 51-29024, Japanese Patent Publication No. 51-87542, Japanese Patent Publication No. 36864-1982, Japanese Patent Publication No. 36519-1987, etc., respectively.

However, in the case of the former multicolor thermosensitive recording paper,
When coloring at a high temperature, the color tones that can be specifically achieved in order to mix the color with the color tone of the low temperature coloring layer are limited to black threads that have hiding power, such as red-black, blue-black, etc. There is. On the other hand, in the case of the latter multicolor thermosensitive recording paper, the combination of color tones can be freely selected, but the low temperature coloring layer must be decolored during high temperature coloring, and various decoloring agents are used for this purpose. Materials have been provided, but I have not found anything satisfactory at the moment. For example, Japanese Patent Publication No. 51-19992 discloses acetamide, stearamide, phthalonitrile, m-nitroaniline, β-naphthylamine, etc. Among these, stearamide and phthalonitrile are generally used as sensitizers. It can be used, and its decolorizing effect is negligible. Although m-nitroaniline and β-naphthylamine show some decoloring effect, they are extremely degradable and not only quickly turn yellow, but also have high water solubility, so they quickly decolorize even low-temperature colored images. It also has toxicity such as skin irritation, so it cannot be considered a practical material. Japanese Patent Publication No. 54-36864 proposes quaternary ammonium salts of amine derivatives, but quaternary ammonium salts of amine derivatives have high water solubility and poor storage stability of images, making them impractical. In addition, in the case of amine derivatives, hexadecylamine, tribenzylamine, tricyclohexylamine, dioctadecylamine, N,N-dibenzylpiperazine,
Cyclohexyldibenzylamine, etc. are mentioned, but primary amines have poor stability in air, and secondary amines in which only an alkyl group, aryl group, or aralkyl group is substituted for the nitrogen atom, Tertiary amines also have poor storage stability and are not practical. Japanese Patent Publication No. 51-29024 discloses guanidine derivatives, but since guanidine has high water solubility, it is difficult to dissolve in water by attaching a hydrophobic group such as phenyl or cyclohexyl, or by dimerizing it. As such, it is necessary to improve storage stability. Although these materials exhibit a certain degree of color erasing effect and can be said to be practically practical materials, they have the disadvantage of being easily thermally decomposed, and have the problem of being prone to gas generation and having poor storage stability.

Considering the above problems, the material properties required for a color erasing agent are that it should be basic, be sparingly soluble in water, have a melting point of at least 80°C, and be resistant to air or heat. Examples include stability and low toxicity.

〔the purpose〕

The present invention uses a specific color erasing agent to provide clear two-color development with good color separation and no color mixture, and also provides two-color recording with high density and excellent stability over time. The purpose of the present invention is to provide a color-developing thermosensitive recording material.

〔composition〕

According to the present invention, first and second heat-sensitive coloring layers each having different coloring heat energy and producing different color tones are stacked on a support such that the one with lower coloring heat energy is the upper layer. In the two-color heat-sensitive recording material, the above-mentioned 2
The second thermosensitive coloring layer forming at least the upper layer of the two thermosensitive coloring layers is constructed using a coloring system consisting of a basic leuco dye and a color developer, and a decoloring agent for the coloring system of the second thermosensitive coloring layer. As, at least one kind selected from the piperazine derivatives represented by the following general formulas (1), (■), and (III) is present at a position where it can have a decoloring effect on the coloring system of the second thermosensitive coloring layer. A two-color heat-sensitive recording material is provided.

General formula (1) General formula (II) (R)n General formula (m) In the general formulas (1), (II) and (III), R□ and R2 are alkyl which may have a substituent , cycloalkyl, aryl or aralkyl, X is carbonyl or sulfonyl, R is lower alkyl,
n is an integer from 0 to 2. The alkyl represented by R1 and R2 is usually a straight chain or branched chain having 1 to 18 carbon atoms, the cycloalkyl is cyclohexyl, and the aryl is phenyl, I-lyl, etc. , xylyl, etc., and examples of aralkyl include benzyl, phenethyl, etc. These substituents can further have other substituents, such as alkyl, aryl,
In addition to halogen, alkoxy, aryloxy, acyl, acyloxy, and alkoxycarbonyl can be used. As lower alkyl represented by R,
Examples include methyl, ethyl, propyl, butyl, hexyl and the like.

Specific examples of compounds represented by the general formula → are:
For example, the following can be mentioned.

N-methyl-N'-phenylacetylpiperazine, N-
Propyl-N'-phenylacetylpiperazine, N-propyl-N'-benzoylpiperazine, N-butyl-N'-benzoylpiperazine, N-cyclohexyl-N'-benzoylpiperazine, N-hexyl-N'-ben Soilpiperazine, N-lauryl-N'-benzoylpiperazine, N-stearyl-
N'-benzoylpiperazine, N-phenyl-N'-benzoylpiperazine, N-benzyl-N'-benzoylpiperazine, N-phenyl-N'-cyclohexyloylpiperazine, N-phenyl=N'-acetylpiperazine, N -Phenyl-N'-lauroylpiperazine, N-phenyl-N'
-p-methylbenzoylpiperazine, N-phenyl-N7-p-chlorobenzoylpiperazine.

N-Benzoylaminoethyl-N'-benzoylpiperazine.

N-benzoylaminopropyl-N'-benzoylpiperazine, N-benzoylaminobutyl-N'-benzoylpiperazine, N-benzoylaminopropyl-N'-cyclohexylpiperazine, N-cyclohexylaminopropyl-N'-cyclo Hexyloylpiperazine, N-benzoylaminoamyl-N'benzoylpiperazine, N-(p-chlorobenzoylaminoamyl) -N'-
(chlorobenzoyl)piperazine, N-phenyl-N'-benzenesulfonylpiperazine, N-benzyl-N'-benzenesulfonylpiperazine, N-methyl-N'-benzenesulfonylpiperazine, N-propyl-N'-benzenesulfonyl Piperazine, N-butyl-N'-benzenesulfonylpiperazine, N-hexyl-N'-benzenesulfonylpiperazine, N-cyclohexyl-N'-benzenesulfonylpiperazine, N-lauryl-N'-benzenesulfonylpiperazine .

N-stearyl-N'-benzenesulfonylpiperazine, N-phenyl-N'-butylsulfonylpiperazine, N-phenyl-N'-laurylsulfonylbiperazine, N-phenyl-N'-stearylsulfonylpiperazine, N-phenyl -N'-cyclohexylsulfonylpiperazine, N-phenyl-N'-benzylsulfonylpiperazine, N-phenyl-N'-(p-methylbenzenesulfonylN-butyl-N'-(p-methylbenzenesulfonyl ) piperazine.

N-benzoylaminopropyl-N'-benzenesulfonylpiperazine, N-benzoylaminopropyl-N'-p-methylbenzenesulfonylpiperazine, N-benzoylaminoethyl-N'-benzenesulfonylpiperazine, N-benzoylaminobutyl-N' -benzenesulfonylpiperazine, N-benzoylaminopropyl-N'-butanesulfonylpiperazine, N-naphthoylaminopropyl-N'-benzenesulfonylpiperazine, N-benzenesulfonylaminopropyl-N'-benzenesulfonylpiperazine, N-butyroyl Aminopropyl-N'-benzoylpiperazine, N-hexyloylaminopropyl-N'-benzoylpiperazine, N-lauroylaminopropyl-N'-benzoylpiperazine, N-stearoylaminopropyl-N'-benzoylpiperazine.

N-stearoylaminopropyl-N'-benzenesulfonylpiperazine and the like.

Specific examples of the compound represented by the general formula (Il) include the following.

N,N'-bis(benzenesulfonyl)piperazine,
N,N'-bis(P-methylbenzenesulfonyl)piperazine, N,N'-bis(p-isopropylbenzenesulfonyl)piperazine, N,N'-bis(ρ-chlorobenzenesulfonyl)piperazine, N,N'-bis (0-chlorobenzenesulfonyl)piperazine, N,N'-bis(Ill-chlorobenzenesulfonyl)piperazine, N,N'-bis(p-bromobenzenesulfonyl)piperazine, N,N'-bis(butylsulfonyl)piperazine, N
, N'-bis(octylsulfonyl)piperazine, N
, N'-bis(laurylsulfonyl)piperazine, N
, N'-bis(stearylsulfonyl)piperazine, N,N'-bis(cyclohexylsulfonyl)piperazine, -N,N'-bis(p-laurylbenzenesulfonyl)
Piperazine, N,N'-bis(cyclohexylsulfonyl)piperazine, N-butylsulfonyl-N'-benzenesulfonylpiperazine, N-octylsulfonyl-N'-benzenesulfonylpiperazine, N-(o-chlorobenzenesulfonyl)-N '-benzenesulfonylpiperazine, N-lauroyl-N'-benzenesulfonylpiperazine, N-lauroyl-N'-(p-methylbenzenesulfonyl)piperazine, N-benzoyl-N'-benzenesulfonylpiperazine.

N-(o-chlorobenzoyl)-N'-benzenesulfonylpiperazine, N-(o-methylbenzoyl)-N'-benzenesulfonylpiperazine, and the like.

Specific examples of the compound represented by the general formula (III) include the following.

N,N'-bis(butyroyl)piperazine, N,N'
-bis(hexyloyl)piperazine, N,N'-bis(n-ofthyroyl)piperazine, N,N'-bis(tertiary-ofthyroyl)piperazine, N,N'-bis(lauriloyl)piperazine, N,N
' -Bis(stearoyl)piperazine, N, N' -
Bis(pivaloyl)piperazine, N,N'-bis(cyclohexyloyl)piperazine, N,N'-bis(P
-methylcyclohexyloyl)piperazine, N,N'-bis(p-methylphenylacetyl)piperazine, N,N'-bis(phenylacetyl)piperazine, N
, N'-bis(phenylpropionyl)piperazine, N,N'-bis(benzoyl)piperazinone, N,N
'-bis(phenoxyacetyl)piperazine, N,N
'-bis(p-chlorobenzoyl)piperazine, N,
N'-bis(2-phenoxypropionyl)piperazine, N,N'-bis(m-chlorobenzoyl)piperazine,
N,N'-bis(0-chlorobenzoyl)piperazine, N,N'-bis(p-methylbenzoyl)piperazine, N,N'-bis(m-methylbenzoyl)piperazine, N,N'-bis(0 -methylbenzoyl)piperazine, N,N'-bis(0-acetyloxybenzoyl)piperazine.

N,N'-bis(0-butyryloxybenzoyl)piperazine.

N,N'-bis(p-phenylbenzoyl)piperazine, N,N'-bis(P-methoxycarbonylbenzoyl)piperazine, N,N'-bis(p-isopropoxycarbonylbenzoyl)piperazine, N,N'- Bis(p-octadecylcarbamoylbenzoyl)piperazine and the like.

The above compound used as a decolorizing agent in the present invention may be used alone or in combination.
These are usually white, air-stable solids, and in the case of the present invention, 80%
Those having a melting point of 120 to 250°C are preferably used.

The color erasing agent used in the present invention has a high color erasing effect on the coloring system of the second thermosensitive coloring layer, which is composed of a basic leuco dye that develops color with low thermal energy and its color developer. In the present invention, the decoloring agent may be present at a position where it can decolor the coloring system of the second thermosensitive coloring layer when coloring the first thermosensitive coloring layer with high thermal energy; Intermediate layer (decoloring agent layer) between the heat-sensitive coloring layer and the first heat-sensitive coloring layer
is provided and contained in this intermediate layer, or it can be contained in the first thermosensitive coloring layer.

In the present invention, the coloring agent used in the second thermosensitive coloring layer may be any coloring agent as long as it forms a stable image when heated with low energy and is easily erased with a decoloring agent when heated with high energy. , a basic leuco dye is used. 1st
The coloring agent used in the thermosensitive coloring layer may be any coloring agent as long as it is not easily erased by the decoloring agent. Therefore, the coloring agent used in the first thermosensitive coloring layer is not limited to leuco dyes, but may be other conventionally known thermosensitive dyes. Color-producing ones are also used.

The two-color heat-sensitive recording material of the present invention has high background whiteness and maintains this whiteness over time, and also has high low-temperature color development image density and maintains this image density over time. The high-temperature colored image is clear without color mixture, and is stable both initially and over time. In the two-color heat-sensitive recording material of the present invention, if necessary, the space between the decoloring agent layer and the first thermosensitive coloring layer, between the decoloring agent layer and the second thermosensitive coloring layer, or the first coloring layer containing the decoloring agent is provided. An intermediate layer, such as a thermofusible material, between the thermosensitive coloring layer and the second thermosensitive coloring layer,
A layer containing a water-soluble resin, a latex resin, a filler, etc. may be provided, and a protective layer may be provided on the second thermosensitive coloring layer in the form of one layer or multiple layers.

Furthermore, in the present invention, a back coat layer can be provided on the back surface of the support, an adhesive layer can be provided to form a release paper, and a magnetic layer can be provided to form a magnetic ticket paper. .

The basic leuco dye used in the second heat-sensitive coloring layer of the present invention may be applied alone or in a mixture of two or more types, and such basic leuco dyes are applied to this type of heat-sensitive material. For example, leuco compounds of dyes such as triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, and spiropyran-based dyes are preferably used.

Specific examples of such basic 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-dibutylaminophenyl, 3.3-bis(P-dimethylaminophenyl)-6-chlorophthalide, 3.3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6- Chlorfluorane, =20- 3-diethylamino-6-chloro-7-methylfluorane, 3-dimethylamino-5,7-dimethylfluorane, 3
-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6
-Methyl-7-chlorofluorane, 3-(N-p-tolyl-N-ethylamino)-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2- (N-(3'-trifluoromethylphenyl)
amino)-6-dinithylaminofluorane, 2-(3
, 6-bis(diethylamino)-9-(o-chloroanilino)xantylbenzoic acid lactam), 3-diethylamino-6-methyl-7-(m-trichloromethylanilino)fluoran, 3-diethylamino-7-(o- 3-dibutylamino-7-(o-chloroanilino)fluoran, 3-dibutylamino-7-(o-fluoroanilino)fluoran, 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-(N-isoacyl- N-ethyl)amino-7-(0
-chloroanilino)fluoran, 3-(N-hexyl-N-methyl)amino-7-(0-
chloroanilino)fluoran 3-(N,N-diethylamino)-5-methyl-7-(
N.

N-dibenzylamino)fluoran, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrylospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrylospirane.

3-(2'-hydroxy-41-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-47-chloro-5'
-methylphenyl)phthalide, 3-morpholino-7-(N-propyl-trifluoromethylanilino)fluoran, 3-pyrrolidino-7-(m-trifluoromethylanilino)fluoran, 3-diethylamino-5-chloro- 7-(N-benzyl-trifluoromethylanilino)fluorane.

3-pyrrolidino-7-(di-p-chlorophenyl)=2
3-Methylaminofluoran, 3-diethylamino-5-chloro-7-(α-phenylethylamino 3-(N-ethyl-P-toluidino)-7-(α-phenylethylamino)fluoran, 3-diethylamino- 7-(0-methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7-(α-phenylethylamino)fluoran, 3-diethylamino-7-piperidinofluorane, 2-
Chloro-3-(N-methyltoluidino)-7-(p-n
-butylanilino)fluorane, 3-(N-benzyl-N-cyclohexylamino)-5
, 6-penzo 7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino 4
', 5'-benzofluorane, etc.

In the present invention, as a preferable coloring agent to be contained in the first heat-sensitive coloring layer that forms the high-temperature coloring layer, an acidic leuco dye, for example, an acyl 24- lactone type or sultone type leuco dye as shown below is used. Can be used.

Examples of color developers that can develop color by reacting with the basic leuco dye described above under heat include the following.

N,N'-diphenylthiourea, N-p-ethylphenyl/1z-N'-: phenylthiourea, N-p-butylphenyl=N'-phenylthiourea, N,N'-di-m
-chlorophenylthiourea, N,N'-di-ρ-chlorophenylthiourea, N,N'-di-m-trifluoromethylphenylthiourea, N,N'-di-m-methylphenylthiourea, 4,4 '-isopropylidene diphenol, 4,4'-isopropylidene bis(2-talolophenol), 4,4'-isopropylidene bis(
2,6-dibromophenol), 4,4'-isopropylidene bis(2,6-dichlorophenol), 4,4'
-isopropylidene bis(2-methylphenol), 4
．． 4'-isopropylidene bis(2,6-dimethylphenol), 4,4'-isopropylidene bis(2-te
rlL-butylphenol), 4.4'-5ee-
Butylidene diphenol, 4,4'-cyclohexylidene bisphenol, 4,4'-cyclohexylidene bis(2-methylphenol), 4-SierIX-butylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, α- Naf 1~-le, β-naf 1 hale,
3,5-xylenol, thymol, methyl-4-hydroxybenzoate, 4-hy-1-roxyace-1 hephenone, novolak-type phenolic resin, 2,2'-thiobis(
4,6-dichlorophenol), catechol, resorcinol, hydroquinone, pyrogallol, phloroglycine, fluoroclidine carboxylic acid, 4tert-octylcatechol, 2,2'-methylenebis(4-chlorophenol), 2,2'-methylenebis( 4-methyl-6-ter
t-butylphenol), 2゜2'-dihydroxydiphenyl, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, ethyl p-hydroxybenzoate,
Benzyl p-hydroxybenzoate, p-chlorpencyl p-hydroxybenzoate, 0-chlorobenzyl p-hydroxybenzoate, p-hydroxybenzoate
Methylbenzyl, 〇-octyl P-hydroxybenzoate, benzoic acid, l-hydroxy-2-nano 1-technical acid, 2
-H)roxy-6-naphthoic acid, 4-hydroxydiphenylsulfone, 4-hydroxy-4'-chlorodiphenylsulfone, bis(4-hydroxyphenyl)sulfide, etc.

In the present invention, the coloring system in the first thermosensitive coloring layer is not particularly limited, and in addition to the leuco system described above, various systems such as those shown below can be used.

(a) Combination of long-chain aliphatic iron salts such as ferric stearate and ferric myristylate with phenols such as gallic acid and ammonium salicylate.

(b) Organic acid heavy metal salts such as nickel, cobalt, copper, iron, mercury, silver salts such as acetic acid, stearic acid, and palmitic acid, and salts of organic acids such as calcium sulfide, strontium sulfide, and potassium sulfide. combination with an alkaline earth metal sulfide, or a combination of the organic acid heavy metal salt with an organic chelating agent such as S-diphenylcarbazide or rubazone.

(c) Combinations of heavy metal sulfates such as silver, button, mercury, and 1- to 2-lium sulfates and sulfur compounds such as Na-tetrathionate, sodium thiosulfate, and thiourea.

(2) a ferric fatty acid salt such as ferric stearate;
3. Combination with aromatic polyhydroxy compounds such as 4-dihydroxyna 1-laphenylmethane.

(e) A combination of an organic noble metal salt such as silver oxalate or mercury oxalate and an organic polyhydroxy compound such as polyhydroxy alcohol, glycerin, or glycol.

(f) Combinations of organometallic salts such as silver behenate and silver stearate and aromatic organic ring-forming agents such as protocatechuic acid, spiroindane, and hydroquinone.

(1-) A combination of an aliphatic ferric salt such as ferric pelargonic acid or ferric laurate, and a thiocetyl tribamide or an inthiocetyl tribamide derivative.

(h) A combination of an organic acid lead salt such as lead caproate, lead pelargonate, or lead behenate and a thiourea derivative such as ethylenethiourea or N-dodecylthiourea.

(S) A combination of a higher fatty acid heavy metal salt such as ferric stearate or copper stearate and zinc dialkyldithiocarpanate.

(n) Those that form oxazine dyes, such as the combination of resorcinol and nitroso compounds.

(l) Combination of aromatic diazo compound and coupler.

(w) Combination of formazan compound and metal salt.

In the present invention, in order to bond and support each heat-sensitive color forming layer and decoloring agent layer to the support, various conventional binders can be used as appropriate, such as polyvinyl alcohol,
Starch and its derivatives, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide/
Acrylic ester copolymer, acrylic amide/acrylic ester/methacrylic acid ternary copolymer, styrene/maleic anhydride copolymer alkali salt, imbutylene/
In addition to water-soluble polymers such as maleic anhydride copolymer alkaline salts, polyacrylamide, sodium alginate, gelatin, and casein, polyvinyl acetate, polyurethane, styrene/butadiene copolymers, polyacrylic acid, polyacrylic acid esters, and chloride Latex such as vinyl/vinyl acetate copolymer, polybutyl methacrylate-1-, ethylene/vinyl acetate copolymer, styrene/butadiene/acrylic copolymer, etc. can be used.

In addition, in the present invention, each heat-sensitive color forming layer and color erasing agent layer may further include auxiliary additive components commonly used in this type of heat-sensitive recording material, such as fillers, surfactants, heat-sensitive materials, etc., as necessary. It is also possible to use a fusible substance (or lubricant), etc. In this case, fillers include, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, and surface-treated inorganic fine powders such as calcium and silica. , urea-formalin resin, styrene/methacrylic acid copolymer, polystyrene resin, and other organic fine powders. Examples of thermofusible substances include higher fatty acids or their esters, amides, or metal salts. In addition, various waxes, condensates of aromatic carboxylic acids and amines, benzoic acid phenyl esters, higher linear glycols,
dialkyl 3,4-epoxy-hexahydrophthalate,
50-2 of higher ketones, other thermofusible organic compounds, etc.
Examples include those having a melting point of about 00°C.

In order to obtain the heat-sensitive recording material of the present invention, a liquid in which color-forming dyes, color developers, decolorizers, binders, etc. are dispersed or dissolved is coated on a support such as paper, synthetic paper, or plastic film and dried. ,
You can get it by repeating it. When using one unit 32 for further lamination on top of the coated layer, it is necessary to pay close attention to the solubility and releasability of the layer so as not to mix it with the lower layer or two layers. Further, after coating and drying, the upper layer may be applied after calendering. Dye (-J coverage amount is 0.3g/ml to 1.0g/ml for high temperature coloring layer)
Og/rrf' is preferred, and the ratio of dye and developer is 1:
A weight ratio of 1 to 1:5 is preferred. The decolorizing agent attachment group of the decolorizing agent layer is preferably 1.0 g/rn' to ]Og/m.

In addition, it is preferable that the amount of the dye adhered to the low-temperature coloring layer be large in order to increase the density, but it is preferable to have a small amount in order to enhance the decoloring effect and to reduce the cost.Usually, the amount of dye adhered is 0.2 g/m to 0.6 g/m is preferable.

The ratio of dye to color developer is preferably I:1 to 1:3 by weight. When providing a protective layer, the amount of adhesion is 0.5g#rl~
5.0 g/rrr is preferred. When an intermediate layer is provided between the decoloring agent layer and the low-temperature coloring layer or between the decoloring agent layer and the high-temperature coloring layer, the former is preferably 0.5 g/m to 5.0 g/rJ, and the latter is Ig/ rrr~Log/m is preferable.

〔effect〕

The two-color thermosensitive recording material of the present invention has the above-mentioned structure, and the decolorizing agent used in the present invention is superior to the coloring system consisting of a combination of a basic leuco dye and a color developer in the second thermosensitive coloring layer. Since it exhibits a color erasing effect and has a high color erasing effect even when a black color is developed, according to the present invention, it is possible to obtain a heat-sensitive recording material that exhibits clear two-color separation even in a color configuration where the basic color tone is black. Moreover, the obtained image has good stability.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples. Note that all parts and percentages shown below are based on weight.

Example 1 [A, Liquid] 10 parts of 3-diethylamino-7-chlorofluorane 10% aqueous solution of styrene-maleic anhydride copolymer 10 parts of water

30 parts (Liquid A2) 3-dibutylamino-7-(o-chloroanilino)fluoran 10 parts Styrene-
10% aqueous solution of maleic anhydride copolymer 10 parts water
30 parts CBt liquid] 4.4'-diphenolsulfone 30 parts polyvinyl alcohol 10% aqueous solution 30 parts water

90 parts (Liquid B2) 3.3'-Dichlorodiphenylthiourea 30 parts Polyvinyl alcohol 10% aqueous solution 30 parts Water
9
0 parts [Liquid C] Calcium carbonate 20 parts Polyvinyl alcohol 10% aqueous solution 10 parts Zinc stearate 5 parts Water
65 copies [D
Liquid] Erasing agent shown in Table 1 below 80 parts Polyvinyl alcohol] 0% aqueous solution 80 parts Water
240 copies [
Solution E] Polyvinyl alcohol 10% aqueous solution 20 parts Silica fine particles 0.5 parts Zinc stearate 0.1 part Water
10 copies [F
Liquid] Polyvinylidene chloride latex 10 parts (solid content 50%) Highly concentrated polyethylene wax dispersion liquid 40 parts (solid content 25%) Among the above [liquid A] to [liquid F], first, CAx liquid]:
[Liquid B1]: Mix [Liquid C] in a ratio of 1:1:1,
A first coloring layer (high temperature coloring layer) coating liquid was prepared. This is 50g/rr? Color-forming dye adhesion amount on high-quality paper is 0.5
It was coated with a lab coating rod in a ratio of g/a and dried to obtain a high-temperature coloring layer.

Next, the [liquid D] was coated on the high temperature color forming layer and dried to obtain a color erasing agent layer so that the dry adhesion amount was 4 g/rd.

Next, the above (Liquid A2), [Liquid B2] and [Liquid C] were mixed in 1:
A second coloring layer (low-temperature coloring layer) coating solution was prepared by mixing at a ratio of 1:1, and this was lab-coated onto the decolorizing agent layer so that the amount of coloring dye deposited was 0.4g/rrF. It was applied with a rod and dried to form a low-temperature coloring layer.

Next, the above-mentioned [Liquid E] was applied and dried on the low-temperature color forming layer to a dry adhesion amount of 3 g/I to form a protective layer.

The surface of the two-color thermosensitive recording paper obtained as described above was calendered.

Next, this two-color thermal recording paper was printed using a facsimile printing device with an applied energy of 0.9 mJ/dot to perform low-temperature coloring, and then printed with an applied energy of 3.0 mJ/dot. However, when high temperature coloring was performed, a clear black image with an image density of 1.0 or more was obtained with low temperature coloring, and a clear non-reddish image without blackness was obtained with high temperature coloring. All of these images were stable and did not deteriorate over time even when left indoors.

The image of the red chromogenic leuco dye used in this example is
For example, in Japanese Patent Publication No. 54-36863, it is said that the color is easily erased, but in this example, such a problem did not occur, and it was confirmed that the image was stable and had high density.

Table 1 Example 2 Experiment Nnl of Example 1 was carried out except that the above-mentioned [Liquid F] was used to form an intermediate layer with a dry adhesion amount of 2 gems between the decoloring agent layer and the warm color forming layer. A two-color thermal recording paper was obtained in the same manner as in Example 1. As in the case of Example 1, this thermal recording paper also has clear, high-density, stable black and vermilion red colors.
gave a color image. This colored black image was stable even after being left in a constant temperature bath at 40° C. for one week.

Example 3 In experiment Nα1 of Example 1, the above [Liquid F] was used between the decoloring agent layer and the low-temperature coloring layer and between the high-temperature coloring layer and the decoloring agent layer, and the dry adhesion amount was 2 g/rrr. A two-color thermosensitive recording paper was obtained in the same manner as in Experiment Nα1 of Example 1, except that the intermediate layers were respectively formed. Similar to the case of Example 1, this thermosensitive recording paper also provided a stable two-color image of black and vermilion red with clearness and high density.

Comparative Examples 1 to 3 In Example 1, octadecylamine (Comparative Example 1), tribenzylamine (Comparative Example 2), and N,N,N',N'-tetrabenzylhexamethylenediamine ( A two-color thermal recording paper was obtained in the same manner as in Example 1 except that Comparative Example 3) was used. In the case of these thermosensitive recording papers, the yellow background was noticeable during the preparation stage, and the yellowing increased significantly over time. In addition, the density of black coloring is low,
It could not be called a practical image. In addition, most of the colored images faded over time.

Example 4 [Dispersion A] 3-(N-ethyl-N-amylamino)-6-methyl-
7-anirithufluoran (black) 20 parts 10% hydroxyethyl cellulose aqueous solution 20 parts water
60 parts (Dispersion B) 3.3'-Dichlorophenylthiourea 12 parts Stearic acid amide 6 parts Calcium carbonate 12 parts lO% polyvinyl alcohol aqueous solution 30 parts Water
40 parts [Dispersion C] 3-diethylamino-7-chlorofluoran (red)
20 parts 10% hydroxyethyl cellulose aqueous solution 20 parts water

60 parts [Dispersion D] Bisphenol A 12 parts Ethylene bisstearamide 6 parts Calcium carbonate 9 parts 10% polyvinyl alcohol aqueous solution 30 parts Water
43 parts [Dispersion E (erasing agent layer forming liquid)] N,N'-bis(stearylsulfonylpiperazine(
Decoloring agent) 20 parts 10% polyvinyl alcohol aqueous solution 20 parts water
6
o part The above dispersions A to E are mixed according to the contents of Table 2, and
(low temperature) thermosensitive color forming layer forming liquid, decoloring agent layer forming liquid and second (low temperature)
After preparing a heat-sensitive coloring layer forming solution (high temperature), coating and drying these on commercially available high-quality paper (basis weight 52 g/rrF) in sequence, calendering was performed to obtain a smoothness of 500 to 1500 seconds. A color-developing thermosensitive recording material was obtained.

Table 2 Example 5 The decolorizing agent of dispersion E of Example 4 was N,N'-bis(p
A two-color thermosensitive recording material of the present invention was obtained in the same manner as in Example 1, except that methylbenzenesulfonyl)piperazine was used.

Example 6 A two-color thermosensitive recording material of the present invention was obtained in the same manner as in Example 1 except that the decolorizing agent in Dispersion E of Example 4 was changed to N,N'-bis(benzoyl)piperazine. .

Example 7 Example 1 except that the decolorizing agent in dispersion E of Example 4 was changed to N,N'-bis(cyclohexyloyl)piperazine.
In the same manner as above, a two-color thermosensitive recording material of the present invention was obtained.

Comparative Example 4 A comparative two-color thermosensitive recording material was obtained in the same manner as in Example 1, except that the decolorizing agent in Dispersion E of Example 4 was changed to tribenzylamine.

Example 8 [Dispersion F] 3.6-diacetyloxy 4', 5', 6', 7
'-Tetrachlorofluorescein 2
0 parts 10% hydroxyethyl cellulose aqueous solution 20 parts water
60 parts of this dispersion F and the dispersion A of Example 4,
r3. Prepare each coating solution as shown in Table 3 using E.
This was sequentially coated on a commercially available high-quality paper having a basis weight of 52 g/m, dried, and then calendered in the same manner as in Example 4 to obtain a two-color thermosensitive recording material of the present invention.

Table 3 Example 9 In Example 8, as the decolorizing agent in dispersion E, N, N
A two-color thermosensitive recording material of the present invention was obtained in the same manner as in Example 8 except that '-bis(benzoyl)piperazine was used.

43-Example 10 [Dispersion G] Ferric stearate 20 parts 10
% polyvinyl alcohol aqueous solution 20 parts water
60
Parts [Dispersion H] 1-formyl-4-phenyl semicarbazide 20 parts 10% polyvinyl alcohol aqueous solution 20 parts water
6
0 parts of these dispersions G, H and dispersion A of Example 4,
Using B and E, prepare each coating solution with the contents shown in Table 4,
This was successively coated and dried on commercially available high-quality paper with a basis weight of 52 g/nf, and then calendered in the same manner as in Example 4 to obtain a two-color thermosensitive recording material of the present invention.

Table 4 44-Example 11 In Example 10, as a decolorizing agent in dispersion E, N,
A two-color heat-sensitive recording material of the present invention was obtained in the same manner as in Example 10 except that N'-bis(benzoyl)piperazine was used.

The two-color heat-sensitive recording material obtained as described above was tested for dynamic color density using a G-m facsimile test machine, and further tested for weather resistance of the colored image area and background area. The results are shown in Table 5 below.

The test machine was an 8 dot/m manufactured by Matsushita Electronic Components Co., Ltd.
The heating resistor has a thermal head of approximately 400Ω/m.
This is a dot at a main scanning recording speed of 20m5ec/1.
ine, sub-scanning 3.85 Q/mm, platen suppression 3
．． 0kg/A-4T1], the head input is 1, 0 mj/dot for low temperature coloring (second thermosensitive coloring layer coloring), and 3.0mj/dot 1- for high temperature coloring (first thermosensitive coloring layer coloring).
I did it.

As can be seen from Table 5, in the two-color heat-sensitive recording material of the present invention, the color tone of the low-temperature color-forming layer can be achieved with black thread, and there is no problem even when a conventional heat-sensitive recording layer is used in the high-temperature color-forming layer. In addition, it is a two-color thermosensitive recording material that has excellent color separation without color mixing and can provide images with stable quality over time.

Claims (1)

[Claims] (1) Each coloring heat energy is different on the support,
In a two-color thermosensitive recording material in which first and second thermosensitive coloring layers that develop colors in different tones are stacked so that the one with lower coloring heat energy is the upper layer, at least of the two thermosensitive coloring layers The second thermosensitive coloring layer forming the upper layer is constructed using a coloring system consisting of a basic leuco dye and a color developer, and as a decoloring agent for the coloring system of the second thermosensitive coloring layer, the following general formula (I ), (II) and (III), wherein at least one kind selected from the piperazine derivatives represented by (II) and (III) is present in a position where it can act as a decolorizer on the coloring system of the second thermosensitive coloring layer. Heat-sensitive recording material. General formula (I) ▲Contains mathematical formulas, chemical formulas, tables, etc.▼ General formula (II) ▲Contains mathematical formulas, chemical formulas, tables, etc.▼ General formula (III) ▲Contains mathematical formulas, chemical formulas, tables, etc.▼ (General formula ( In I), (II) and (III), R_1 and R_2 are alkyl, cycloalkyl, aryl or aralkyl which may have a substituent, X is carbonyl or sulfonyl, and R is lower alkyl. (n is an integer from 0 to 2.)