JPH01130974A - Bicolor thermosensitive recording material - Google Patents

Abstract

PURPOSE:To obtain a sharp high temperature developed color tone which is not mixed with a low temperature developed color tone by using a specific compound as a discharging agent of a discharging layer and at the same time, limiting the bulk mean particle size of leuco dye in a low temperature color developing layer in a specific range. CONSTITUTION:A bicolor thermosensitive recording material consists of a high temperature color developing layer, a discharging layer and a low temperature color developing layer laminated sequentially on a support. The discharging agent of a discharging layer used is a compound such as shown by a formula (1) (in the formula, A is alkylene, phenylene, tolylene and xylene, R1, R2, R3 & R4 are substituted or unsubstituted alkyl, cycloalkyl, aryl or aralkyl, and R1 & R2 or R3 & R4 may form a ring through coupling of their ends). In addition, the bulk mean particle size of leuco dye in the low temperature color developing layer is 0.8mum-1.8mum. In this way, a low temperature developed color tone of high density is obtained at low temperature, while the low temperature developed color tone is adequately discharged at high temperature. Thus a bicolor thermosensitive recording material which provides a sharp high temperature developed color tone which is not mixed with a low temperature developed color tone due to the adequate discharging of the low temperature developed color tone at high temperature, is obtained.

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 leuco dye that is usually colorless or slightly pale in color, and a color developer that reacts with the leuco dye when heated to develop a color. It relates to a two-color heat-sensitive recording material formed by laminating heat-sensitive coloring layers containing as a main component.

[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. Agent (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. However, depending on the purpose of recording, in order to display particularly necessary data and numbers more clearly, the coloring of that part (
It goes without saying that it is desirable to be able to record with the display color (displayed color) different from the developed color of other parts.

Recently, attempts have been made to obtain multicolor recording by utilizing differences in heating temperature or thermal energy, and various multicolor thermosensitive recording papers have been proposed accordingly. Multi-color thermosensitive recording paper is generally formed by stacking two types of high-temperature and low-temperature coloring layers that develop different tones using different coloring heat energies on a support, and can be roughly divided into the following two types: Divided into types. One is to mix the color with the color tone of the low temperature coloring layer when coloring the high temperature coloring layer to obtain a color tone different from the coloring tone of the low temperature coloring layer, and the other is to color the high temperature coloring layer. In this case, by using a decoloring agent that decolorizes 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 specific examples of these, the former is disclosed in Japanese Patent Publication No. 49-69, Japanese Patent Publication No. 49-4342, Japanese Patent Publication No. 49-27708,
JP-A-48-86543, JP-A-49-6523
9, etc., and the latter was published in the Special Publication No. 1973.
-17865, Japanese Patent Publication No. 50-17'866, Japanese Patent Publication No. 51-29024, Japanese Patent Publication No. 51-875
Publication No. 42, Japanese Unexamined Patent Application Publication No. 18048/1983, Japanese Patent Publication No. 18048/1983
These are disclosed in Japanese Patent No. 5-36519 and the like.

However, in the case of the former multicolor thermosensitive recording paper,
When coloring at a high temperature, the color tones that can be concretely achieved in order to mix the color with the color tone of the low temperature coloring layer are limited to black threads where the high temperature coloring tone is strong, 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 when coloring at high temperatures, high aliphatic alcohols, polyethers, polyethylene glycol derivatives,
Acetamide, stearamide, phthalonitrile as nitrogen-containing organic compounds, guanidine derivatives, morpholine derivatives, etc. as amine derivatives are used.

However, in such recording materials that develop multiple colors, it is important that the low-temperature color-developing layer not only develops color with high density at low temperatures, but also that the low-temperature color-developing layer sufficiently erases color with the decolorizing layer at high temperatures. It is.

However, heating causes color development (at low temperatures),
On the other hand, we want contradictory functions of decoloring (at high temperatures), so if we increase the coloring function at low temperatures, even at high temperatures, the coloring function of the low temperature coloring layer is better than the coloring function of the decolorizing layer. The color tone of high temperature coloring becomes mixed with the color tone of low temperature coloring. In addition, when trying to improve the color erasing function, the color erasing layer starts to emit the color erasing function at low temperatures,
A problem has arisen in that the low-temperature color tone is partially faded.

〔the purpose〕

The present invention is an improvement over the prior art, namely, two colors that provide a high-density low-temperature color tone at low temperatures, sufficiently erase the low-temperature color tone at high temperatures, and provide a clear high-temperature color tone without color mixing with the low-temperature color tone. The purpose is to provide heat-sensitive recording materials.

〔composition〕

According to the present invention, in a two-color thermosensitive recording material in which a high-temperature coloring layer, a color-erasing layer and a low-temperature coloring layer are laminated in that order on a support, the following general formula (1) is used as a color erasing agent for the color erasing layer. There is provided a two-color thermosensitive recording material characterized in that the volume average particle size of the leuco dye in the low-temperature coloring layer is 0.8 μm to 1.8 μm.

General formula (1) (wherein A represents alkylene, phenylene, tolylene, xylylene, R1, R2, R3 and R4 represent substituted or unsubstituted alkyl, cycloalkyl, aryl or aralkyl, R□ and R2 or (The ends of R3 and R4 can be bonded to each other to form a ring.) In the present invention, the compound of general formula (1) is used as the decolorizing agent in the decolorizing layer, and the compound in the low temperature coloring layer is By setting the volume average particle size of the leuco dye to 0.8 μm to 1.8 μm, it provides a highly concentrated low-temperature color tone at low temperatures, the low-temperature color tone is sufficiently erased at high temperatures, and there is no color mixing with the low-temperature color tone. It is possible to obtain a two-color heat-sensitive recording material that provides clear high-temperature color tone.

Specific examples of the compound of general formula (1) used in the present invention include the following.

N, N, N', N'-tetrabutylsuccinic acid diamide, N, N, N', N'-tetraoctylsuccinic acid diamide, N, N, N', N'-tetralauryl succinic acid diamide, N, N,N',N'-tetrastearylsuccinic acid diamide, N,N,N',N'-tetra-p-
Butylphenyladipate diamide, N,N,N',N'-tetrabutyladipate diamide, N,N,N',N'-tetraoctyladipate diamide, N,N,N',N'-tetralauryl Adipic acid diamide, N, N, N', N'-tetrastearin adipic acid diamide, N, N'-dicyclohexyl-N, N'-dimethylsuccinic acid diamide N, N'-isophthaloyl bispyrrolidine N, N'-phthaloylbispyrrolidine, N,N'-terephthaloylbis-diethylamine, N,N'-isophthaloylbis-
Diethylamine, N,N'-phthaloylbis-diethylamine, N,N'-terephthaloylbis-dipropylamine, N,N'-isophthaloylbis-dipropylamine, N,N'-terephthaloylbis-dipropylamine butylamine,
N, N'-isobutaroylbis-dibutylamine, N,
N'-terephthaloylbis-cyclohexyl-methylamine, N,N'-isophthaloylbis-cyclohexyl-methylamine, N,N'-terephthaloylbis-dicyclohexyl-amine, N, N'-isophthaloylbis-dicyclohexyl-amine, etc.

In the present invention, examples of the color developer contained in the high-temperature coloring layer and the low-temperature coloring layer include N,N'-diphenylthiourea, N-p-ethylphenyl-N'-phenylthiourea, and N-P-butylphenyl. -N'-phenylthiourea, N,N'-di-m-chlorophenylthiourea, N,
N'-di-P-chlorophenylthiourea, N,N'-
Di-m-trifluoromethylphenylthiourea, N,N
' -di-m-methylphenylthiourea, 4,4' -
Isopropylidene diphenol, 4,4'-isopropylidene bis(2-chlorophenol), 4,4'-
Isopropylidene bis(2,6-dibromophenol)
, 4,4'-isopropylidene bis(2,6-dichlorophenol), 4,4'-isopropylidene bis(
2-methylphenol), 4,4'-isopropylidenebis(2-tert-butylphenol), 4.4'
-5ee-butylidene diphenol, 4.4'-cyclohexylidene bis(2-methylphenol), 4-
tert-butylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, α-naphthol, β
-Naphthol, 3,5-xylenol, thymol, methyl-4-hydroxybenshade, 4-hydroxyacetophenone, novolac type phenolic resin, 2,2'-
Thiobis(4,6-dichlorophenol), catechol, resorcinol, hydroquinone, pyroganol, phloroglucin, phloroglycin carboxylic acid, 4-tert-
Octylcatechol, 2,2'-methylenebis(4-
chlorophenol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'
-dihydroxydiphenyl, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate,
p-chlorobenzyl p-hydroxybenzoate, 0-chlorobenzyl p-hydroxybenzoate, p-methylbenzyl p-hydroxybenzoate, n-octylbenzoic acid p-hydroxybenzoate, zinc salicylate, 1- Hydroxy-2-naphthoic acid, 2-hydroxy-6-naphthoic acid, zinc 2-hydroxy-6-naphthoic acid, 4-hydroxydiphenylsulfone, 4-hydroxy-4'-
In addition to chlorodiphenyl sulfone, bis(4-hydroxyphenyl) sulfide, and the like, guanidine-based organic base color developers shown below may also be used.

The leuco dyes used in the present invention can be applied singly or in combination of two or more types, but such leuco dyes include:
Those applied to this type of heat-sensitive material can be arbitrarily applied. For example, leuco compounds of dyes such as triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, and indolinophthalide-based 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-dibutylaminophenyl, 3.3-bis(p-dimethylaminophenyl)-6-chlorophthalide, 3.3-bis(P-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6- Chlorfluorane, 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- Chloranilino) fluorane, 3-dibutylamino-? -(o-chloroanilino)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-(N,N- diethylamino)-5-methyl-7-(
N.

N-dibenzylamino)fluorane, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrylospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrylosvirane, 3-(2'- 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-41-chloro-5'
-methylphenyl)phthalide, 3-morpholino-7-(N-propyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7-(N -benzyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-(di-p-chlorophenyl)methylaminofluorane, 3-diethylamino-5-chloro-7-(α-phenylethylamino)fluorane, 3 -(N-ethyl-p-toluidino)-7-(α-phenylethylamino)fluoran.

3-diethylamino-7-(o-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, specific examples of particularly preferable leuco dyes to be included in the high temperature coloring layer include 3-diethylamino-7-chlorofluoran, 3-diethylamino-
Examples include 6-methyl-7-chlorofluoran, 3-cyclohexylamino-6-chlorofluoran, and 3-diethylaminobenzo[α]fluoran. Furthermore, in the high-temperature color forming layer, acylated lactone or sultone type acid leuco dyes as shown below can also be used in combination with the above-mentioned guanidine color developer.

161 In the present invention, in order to bind and support the leuco dye, developer, and decolorizer on the support, various commonly used binders can be used as appropriate, such as polyvinyl alcohol, starch, and their like. derivatives, methoxycellulose,
Cellulose derivatives such as hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide/acrylic acid ester copolymer, acrylamide/acrylic acid ester/methacrylic acid ternary copolymer, styrene Water-soluble polymers such as / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, polyvinyl acetate, polyurethane, styrene/butadiene copolymer Latexes such as polyacrylic acid, polyacrylic acid ester, vinyl chloride/vinyl acetate copolymer, polybutyl methacrylate, ethylene/vinyl acetate copolymer, styrene/butadiene/acrylic copolymer, etc. can be used.

In addition, in the present invention, in addition to the leuco dye and color developer, if necessary, auxiliary additive components commonly used in this type of heat-sensitive recording material, such as fillers, surfactants, thermofusible substances ( or lubricant), etc. can be used in combination. 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-polymarine 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-hexahydrophthalates, higher ketones, and other thermofusible organics. Examples include compounds having a melting point of about 50 to 200°C.

Further, in the present invention, an intermediate layer may be provided between the high-temperature coloring layer and the decoloring layer and between the decoloring layer and the low-temperature coloring layer, if necessary.

The softening point of the film-forming polymer binder contained in the intermediate layer is preferably around 100°C, more preferably 80°C to 120°C.
It is ℃. Examples of such binders include polyvinyl alcohol, polyurethane, hydroxyethyl cellulose, carboxymethyl cellulose, starch and its derivatives, polyvinylidene chloride, styrene/butadiene copolymer, vinyl chloride/vinyl acetate copolymer, styrene/butadiene/ Examples include acrylic copolymers, but the present invention is not limited thereto.

The intermediate layer mainly contains the binder as described above, but each intermediate layer may also contain a thermofusible substance (such as a sensitizer) or a filler.

Furthermore, in the present invention, a protective layer containing the binder, filler, and thermofusible substance as main components may be provided as required.

〔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 [Dispersion A] 10% polyvinyl alcohol aqueous solution 20 parts water
6
0 parts The above was processed using a sand mill until the volume average particle size was 1.
Disperse so that the particle size is 0 μm.

[Dispersion B]

4.4'-thiobis(6-t-butyl-3-methylphenol) 10 parts calcium carbonate
10 parts lO% polyvinyl alcohol aqueous solution 2
0 parts water
60 parts [Dispersion C] 3-diethylamino-7-chlorofluoran (red) 2
0 parts 10% polyvinyl alcohol aqueous solution 20 parts water
60 parts [Dispersion D] Bisphenol A 10 parts Calcium carbonate 10 parts 10% polyvinyl alcohol aqueous solution 20 parts Water
60 parts or more 10 parts of dispersion liquid A prepared as above, 7 parts of dispersion liquid B
0 parts and 20 parts of water were mixed and stirred to obtain a thermosensitive coloring layer forming liquid for low temperature coloring. Next, take 10 parts of dispersion liquid C, 70 parts of dispersion liquid, and 20 parts of water, mix and stir,
A thermosensitive coloring layer forming liquid for high temperature coloring was obtained. Furthermore, a color erasing layer forming liquid for forming a color erasing layer was prepared at the following ratio.

[Decoloring layer forming liquid A]

10% polyvinyl alcohol aqueous solution 20 parts water
6
0 parts A protective layer forming liquid for forming a protective layer was also prepared at the following ratio.

[Protective layer forming liquid]

10% polyvinyl alcohol aqueous solution 20 parts Silica 3 parts Waterproofing agent (
polyamide epichlorohydrin) 10 parts water
47 parts Next, on one side of a commercially available high-quality paper with a basis weight of 52 g/rrr, the above-mentioned thermosensitive coloring layer forming liquid for high temperature coloring (dry coating amount 5.0 g/a) and decoloring layer forming liquid (drying amount 2 .5g/rrr) and thermosensitive coloring layer forming liquid for low temperature coloring (dry coating amount 2.Og/rrr)
A) and a protective layer forming liquid (dry coating amount: 3 g/i) were sequentially applied and dried, and then calendering was performed to obtain a smoothness of 500 to 2000 sec to obtain a two-color heat-sensitive recording material of the present invention.

Example 2 A two-color heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1, except that the volume average particle diameter of the dispersion liquid A in Example 1 was changed to 1.5 μm.

Example 3 [Decoloring layer forming liquid B] 10% polyvinyl alcohol aqueous solution 20 parts water
60
A two-color thermosensitive recording material of the present invention was obtained in the same manner as in Example 1, except that the decoloring layer forming liquid A of Example 1 was replaced with the decoloring layer B liquid.

Comparative Example 1 A two-color thermosensitive recording material of Comparative Example 1 was obtained in the same manner as in Example 1, except that the volume average particle size of the dispersion liquid A of Example 1 was set to 0.3 μm.

Comparative Example 2 A two-color thermosensitive recording material of Comparative Example 2 was obtained in the same manner as in Example 1, except that the volume average particle diameter of the dispersion liquid A of Example 1 was changed to 2.2 μm.

Comparative Example 3 A two-color heat-sensitive recording material of Comparative Example 3 was obtained in the same manner as in Example 1 except that the volume average particle size of the dispersion liquid A of Example 1 was changed to 3.0 μm.

Comparative Example 4 [Decoloring layer forming liquid C] N,N'-bis(benzoylaminoprobyl)piperazine 20 parts 10% polyvinyl alcohol
20 parts water
60 parts A two-color thermosensitive recording material of Comparative Example 4 was obtained in the same manner as in Example 1 except that the decoloring layer forming liquid A of Example 1 was replaced with the decoloring layer forming liquid C.

Comparative Example 5 [Decoloring layer forming liquid D] N,N'-bis(benzenesulfonyl)piperazine
20 parts 10% polyvinyl alcohol 2
0 parts water
60 parts Comparative Example 5 was prepared in the same manner as in Example 1 except that the decoloring layer forming liquid A of Example 1 was replaced with the decoloring layer forming liquid.
A two-color heat-sensitive recording material was obtained.

The two-color heat-sensitive recording materials of Examples and Comparative Examples obtained as described above were tested for heat resistance using samples developed using a Gm facsimile test machine, and the results are shown in Table 1 below.

The test machine has a thermal head of 8 dots/dot manufactured by Matsushita Electronic Components Co., Ltd., the heating element resistance is approximately 400Ω/dot, and the color development test was performed at a main scanning recording speed of 20 m5ec/dot.
1ine sub-scan 3, 851ine/nun platen press 3. Okg/d head input 0, 6w/dot condition, pulse width 1.4m5ec (black coloring) and 4,2
It was carried out using m5ec (red coloring).

In addition, a Macbeth densitometer (RD-514 filter, 106 black color development, 28 red color development, and 25 decolorization density) was used for density measurement.

×Discoloration density refers to the remaining density of black coloring when red coloring occurs.

In addition, the volume average particle diameter was determined using a Coulter counter.
It represents 50% of the volume particle size when measured in ~16 channels.

〔effect〕

The two-color heat-sensitive recording material of the present invention has the above-mentioned structure, exhibits high-density black color development, has no background fog, and has a color image with excellent two-color separation without mixing of black color tones in red color areas. give.

Claims (1)

[Claims] (1) In a two-color thermosensitive recording material in which a high temperature coloring layer, a color erasing layer and a low temperature coloring layer are laminated in that order on a support, a compound of the following general formula (1) is used as a color erasing agent for the color erasing layer. At the same time, the volume average particle size of the leuco dye in the low-temperature coloring layer is 0.
A two-color heat-sensitive recording material characterized by having a diameter of 8 μm to 1.8 μm. General formula (1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, A represents alkylene, phenylene, tolylene, xylylene, and R_1, R_2, R_3 and R_4 are substituted or unsubstituted alkyl, cycloalkyl, aryl. Alternatively, it represents aralkyl, and the terminals of R_1 and R_2 or R_3 and R_4 can be bonded to each other to form a ring.)