JPS60222292A - Two-color thermal recording material - Google Patents

Abstract

PURPOSE:To ensure favorable color separation and ensure that developed color images formed at a high temperature are free of mixing of colors, by using a specified thiourea derivative as the first color developer. CONSTITUTION:A thiourea derivative of the formula, wherein each of R1 and R2 independently represents hydrogen, halogen, trifluoromethyl of 1-4C alkyl, is used as the first color developer, in a two-color thermal recording material having a construction wherein a low-temperature color forming layer comprising the first leuco dye and the first color developer and capable of forming a color at a low temperature and a high-temperature color forming layer comprising the second leuco dye, the second color developer and a decoloring agent for preventing the color forming reaction of the first leuco dye with the first color developer and capable of forming a color at a high temperature with a color tone different from the tone of the color formed by the low-temperature color forming layer are laminated on a base, with the high-temperature color forming layer on the base side. The second color developer may be 4,4'-isopropylidenediphenol. By using the specified thiourea derivative, it is possible to obtain clear two-color images with favorable color separation.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a two-color heat-sensitive recording material, and more particularly to a heat-sensitive recording material provided with two types of leuco-based heat-sensitive coloring layers that develop different colors at different temperatures. It is.

[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 Rafton ring, a lactam ring, a spiropyran ring, etc. in the heat-sensitive color-forming layer, and a color developer that reacts with this leuco dye to form a color 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 and documents, but 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 thermal recording papers generally differ with different color thermal energies on the support. It is formed by overlapping two types of high-temperature and low-temperature coloring layers that develop color tones, and can be roughly divided into the following two 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,
Special Publication No. 49-4342, Special Publication No. 49-27708
No. 48-86543, Japanese Patent Application Laid-open No. 1973-
65239, etc., and the latter is described in Japanese Patent Publications No. 50-17865 and Japanese Patent Publication No. 50-17866.
Publication No. 51-29024, Special Publication No. 51-29024, Publication No. 51-29024
These are disclosed in Japanese Patent Application Laid-open No. 87542, Japanese Patent Application Laid-Open No. 50-18048, Japanese Patent Application Laid-Open No. 53-47843, and the like.

However, in the case of the former multicolor thermosensitive recording paper,
During high-temperature color development, the color tone that can be specifically achieved is red-black because the color is mixed with the color tone of the low-temperature color development layer.

There is a drawback that high-temperature color tones such as blue-black are limited to black threads that have hiding power. On the other hand, in the case of the latter multicolor thermosensitive recording paper, the combination of color tones can be freely selected;
High aliphatic alcohols, polyethers, polyethylene glycol derivatives, ace1-amide, stearamide, phthalonitrile as nitrogen-containing organic compounds, guanidine derivatives as amine derivatives, etc. that decolorize the low temperature coloring layer during high temperature coloring. The agent has a low color-erasing effect and cannot completely erase the color tone of the low-temperature coloring layer during high-temperature coloring, which has the drawback of causing color mixing and causing the low-temperature coloring layer to bleed. To deal with this, it is necessary to apply multiple layers of a high-temperature color forming layer, a decoloring agent layer, and a low-temperature coloring layer, and to make the decolorizing agent layer sufficiently thick. In order to color the high-temperature color-forming layer in facsimiles, etc., high energy is required for the thermal head, and in the case of recorders, when high-speed recording is performed, heat conduction in the depth direction of the thermo-sensitive color-forming layer is low, so the high-temperature coloring in the bottom layer is Problems arise in that the layer does not develop sufficient color and the high temperature coloring layer does not develop sufficient color.

〔the purpose〕

An object of the present invention is to overcome the problems of the prior art described in section 2 and provide a leuco-based two-color thermosensitive recording material that has good color separation and does not cause color mixture in high-temperature color images.

[edge]

According to the present invention, a low-temperature coloring layer containing a first leuco dye and a first color developer and forming a color at a low temperature is formed on a support;
0 ico dye, a second color developer, the 10 ico dye and the first
The low-temperature color-forming layer supports a high-temperature color-forming layer more than the high-temperature color-forming layer, and the high-temperature color-forming layer contains a decoloring agent that prevents color development with a color developer and develops a color tone different from that of the low-temperature color-forming layer at high temperatures. In a two-color heat-sensitive recording material having a laminated structure such that it is located on the upper layer side with respect to the body, the first color developer has the following general formula (wherein 11□ and H2 each independently represent hydrogen, halogen, A two-color heat-sensitive recording material is provided, which is characterized in that it uses a thiourea derivative represented by the formula (representing a trifluoromethyl group or an alkyl group having 1 to 4 carbon atoms).

In the present invention, the conventionally known decolorizers mentioned above can be used. In conventional two-color heat-sensitive recording materials, such decolorizing agents are not effective enough to decolorize the low-temperature heat-sensitive coloring layer composed of leuco dyes and phenolic compounds, and a large amount of decolorizing agent must be used. However, when using the specific thiourea derivative represented by the above general formula as a color developer (first color developer) in a low-temperature coloring layer, it may be sensitive to the action of a decolorizer during melting; , it is possible to obtain satisfactory results with small amounts of decolorizer. In this way, by containing a thiourea derivative in the low-temperature coloring layer and a decoloring agent in the high-temperature coloring layer, the decoloring agent acts on the thiourea derivative in the low-temperature coloring layer when the high-temperature coloring layer develops color. It is possible to prevent color development in the color development layer, and to obtain a two-color thermosensitive recording paper that is free from color mixture and has excellent color separation properties. Specific examples of the thiourea derivative represented by the above general formula include N
, N'-diphenylthiourea, N-p-ethylphenyl-N'-phenylthiourea, N-p-butylphenyl-N'-phenylthiourea, N,N'-Zipeng-chlorophenylthiourea, N,N' -p-chlorophenylthiourea, N,N'-di-m-trifluoromethylphenylthiourea, N,N'-di-methylphenylthiourea, and the like.

On the other hand, a color developer (second color developer) contained in the high temperature coloring layer
Examples include 4,4'-isopropylidene diphenol, 4,4'-isopropylidene bis(2-chlorophenol), 4,4'-isopropylidene bis(2-chlorophenol), and 4,4'-isopropylidene bis(2-chlorophenol).
, 6-dibromophenol), 4.4'-isopropylidene bis(2,6-dichlorophenol), 4.
4'-sopropylidene bis(2-methylphenol), 4,4'-isopropylidene bis(2,6-dimethylphenol), 4,4'-isopropylidene bis(2-tert-butylphenol), C4' -5
ec-butylidene diphenol, 4,4'-cyclohexylidene bisphenol, 4,4'-cyclohexylidene bis(2-methylphenol), 4-tert-butylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, α -naphthol, β-naphthol,
3,5-xylenol, thymol, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, novolac type phenolic resin, 2,2'-thiobis(4,
6-dichlorophenol), catechol, resorcinol,
Hydroquinone, pyrogallol, phloroglycine, phloroglycin carboxylic acid, 4-tert-octylcatechol, 2,2'-methylenebis(4-chlorophenol), 2,2'-methylenebis(4-methyl-6-sier)
t-butylphenol), 2゜2'-dihydroxydiphenyl, ethyl P-hydroxybenzoate, propyl P-hydroxybenzoate, butyl P-hydroxybenzoate,
benzyl p-hydroxybenzoate, p-chlorobenzyl p-hydroxybenzoate, p-hydroxybenzoic acid-
0-Chlorbenzyl, p-methylbenzyl p-hydroxybenzoate JP-octyl hydroxybenzoate.

Benzoic acid, zinc salicylate, l-hydroxy-2-naphthoic acid, 2-hydroxy-6-naphthoic acid, zinc 2-hydroxy-6-naphthoate, 4-hydroxydiphenylsulfone, 4-hydroxy-4'-chlorodiphenylsulfone , bis(4-hydroxyphenyl) sulfide,
etc. are used.

The leuco dyes (first and 20th ico dyes) used in the present invention may be applied alone or in a mixture of two or more, but any leuco dye that has been applied to this type of heat-sensitive material may be used. For example, leuco compounds of triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, and spiropyran-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-dimethylaminophenyl.

3.3-bis(p-dimethylaminophenyl)-6-chlorophthalide.

3.3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlorofluoran.

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'-trifluoran) methylphenyl)
amino)-6-dinithylaminofluorane, 2-(3
, 6-bis(diethylamino)-9-(o-chloroanilino)xantylbenzoic acid), 3-diethylamino-6-methyl-7-(m-trichloromethylanilino)fluoran.

3-diethylamino-7-(0-chloroanilino)fluoran, 3-dibutylamino-7-(o-chloroanilino)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,N-diethylamino)-5-methyl-7-(
N.

N-dibenzylamino)fluoran, benzoylleucomethylene blue, 6'-chloro-81-methoxy-benzoindolino-pyrillospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrillospirane, 3-(2'-hydroxy) -4'-dimethylaminophenyl)-3-(2'-methoxy-5'-chlorophenyl)
nil) 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'-
1 tylphenyl) phthalide.

3-morpholino-7-(N-propyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7-(N-benzyltrifluoro) methylanilino) fluorane.

3-pyrrolidino-7-(di-p-chlorophenyl)methylaminofluorane, 3-diethylamino-5-chloro-7-(α-phenylethylamino)fluoran, 3-(N-ethyl-P-toluidino)- 7-(α-buenylethylamino)fluoran, 3-diethylamino-7-(o-methoxycarbonylphenylamino)fluoran.

3-diethylamino-5-methyl-7-(α-phenylethylamino)fluorane, 3-diethylamino-7-piperidinofluorane, 2-
Chloro-3-(N-methyltoluidino)-7-(p-"
1-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, one example of a particularly preferable leuco dye to be included in the high-temperature coloring layer is as follows.

3-diethylamino-chlorofluoran, 3-diethylamino-6-methyl-7-chlorofluoran.

3-Cyclohexylamino-6-chlorofluorane.

Examples include 3-diethylaminobenzo[α]fluoran.

In the present invention, in order to bind and support the leuco dye and color developer on the support, various commonly used binders can be used as appropriate, such as polyvinyl alcohol, starch and its derivatives, methoxycellulose, hydroxyl, etc. Cellulose derivatives such as ethyl cellulose, carboxymethyl cellulose, methyl cellulose, and ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic amide/acrylic ester copolymer, acryl amide/acrylic ester/methacrylic acid ternary copolymer, styrene/ Maleic anhydride copolymer alkali salt, isobutylene/maleic anhydride copolymer alkali salt,
In addition to water-soluble polymers such as polyacrylamide, sodium alginate, gelatin, and casein, polyvinyl acetate, polyurethane, styrene/butadiene copolymer, polyacrylic acid, polyacrylic ester, vinyl chloride/vinyl acetate copolymer, and Latex such as butyl 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 lubricants) etc. can be used together. 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-polmarine 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, as well as various waxes,
50 such as fasteners of aromatic carboxylic acids and amines, benzoic acid phenyl esters, I-grade linear glycols, dialkyl 3,4-epoxy-hexahydrophthalates, higher ketones, and other thermofusible organic compounds. Examples include those having a melting point of about ~200°C.

In addition, various commonly used decolorizing agents are used in the high-temperature coloring layer, such as polyethers, polyethylene glycol derivatives, solid alcohols, aliphatic or aromatic amines, and guanidine derivatives. 1 morpholine derivatives.

The heat-sensitive recording material of the present invention includes a leuco dye as described above,
A high-temperature coloring layer containing a color developer and a decolorizing agent as main components and a low-temperature coloring layer containing a leuco dye and a thiourea derivative color developer as main components are deposited in this order on a support such as paper, synthetic paper, or plastic film. In this case, these coloring layers may be stacked adjacent to each other, or an intermediate layer may be provided between the two coloring layers. When provided adjacently, thermal printing heat is more easily transmitted to the high-temperature coloring layer than when an intermediate layer is provided, so that the thermal sensitivity of the high-temperature coloring layer increases.

On the other hand, when an intermediate layer is provided, contact between the low-temperature coloring layer and the decoloring agent in the high-temperature coloring layer is prevented at all times except during high-temperature thermal recording, so the density of the low-temperature coloring image decreases over time during storage. It will not fade or fade.

The intermediate layer is composed of a water-soluble polymer binder and a filler. A coloring layer filler is used. The content of the filler in the intermediate layer is preferably 70 to 10% by weight, and the content of the water-soluble polymer binder is preferably 30 to 90% by weight. Further, if necessary, 0 to 20% by weight of a thermofusible substance can be added, and 0 to 20% by weight of an aqueous emulsion type binder can be used together with a water-soluble polymer binder. .

〔effect〕

By using a specific thiourea compound as a color developer in the low-temperature coloring layer, a clear two-color image with good color separation can be obtained.

〔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 was obtained by pulverizing and dispersing the following components using a sand mill so that the volume average particle diameter was 2 to 3 μm.

B, C, D and E were adjusted.

(Dispersion-A) 3-(N-ethyl-N-amylamino)-20 parts 6-methyl-7-anilite fluoran (j% colored leuco dye) 10% hydroxyethyl cellulose aqueous solution 20 water
601F [Dispersion-B] 3.3'-Dichlorophenylthiourea 10 parts Calcium carbonate 1o11 Polyvinyl alcohol (10% aqueous solution) 2o Water 60
[Dispersion-C] 3-diethylamino-7-chlor 2 parts fluorane (
Red leuco dye) 10% hydroxyethylcellulose aqueous solution 20//water 6011 [Dispersion-D] Bisphenol A 10 parts lO% hydroxyethylcellulose aqueous solution 15〃Calcium carbonate 10〃 Water 65〃 [Dispersion-E] 4.4'-dithio Dimorpholine ゛ 20 parts polyvinyl alcohol (10% aqueous solution) 20 Il water 60〃 5 parts of the dispersion liquid A prepared as above, 4 parts of the dispersion liquid B
0 parts were mixed and stirred to obtain a low temperature thermosensitive color forming layer forming liquid. or,
5 parts of dispersion C, 40 parts of 1 dispersion, and 10 parts of dispersion E were mixed and stirred to obtain a high-temperature thermosensitive coloring layer forming liquid. Next, each solution was placed on commercially available high-quality paper with a basis weight of 50 g/rrr, and the dry adhesion amount was 7.5 gIrd for the high temperature thermosensitive color forming layer forming liquid, and 4.0 g Ird for the low temperature heat sensitive color forming layer forming liquid. g
/rf and was sequentially coated and dried to obtain a two-color heat-sensitive recording material of the present invention.

Example 2 Example 1 except that 4,4'-dithiodimorpholine in dispersion E of Example 1 was replaced with octamethylene diamine.
A two-color heat-sensitive recording material of the present invention was obtained in the same manner as described above.

Example 3 The following ingredients were mixed using a sand mill until the volume average particle size was 2 to 3μ.
The mixture was ground to give an intermediate layer formation liquid.

Silica 2.5 parts Polyvinyl alcohol (10% aqueous solution) 60I + Zinc stearate 1,5 n Water 36 In Example 1, after applying and drying the high temperature heat-sensitive coloring layer forming liquid, the intermediate layer forming liquid was applied to the dry coating amount. is 1.5g/
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1, except that it was coated and dried to give nfl.

Comparative Example 1 A comparative two-color heat-sensitive recording material was obtained in the same manner as in Example 1 except that 3,3'-dichlorophenylthiourea in Dispersion E of Example 1 was replaced with benzyl P-oxybenzoate. .

The glossiness (JIS
-p-gx4z&: Measured in accordance with the results) was calendered to about 20 to 25%, and then tested using a G-m facsimile test machine for dynamic color density and separation of various color tones. are shown in Table 1 below.

The test machine had an 8 dot/a+m thermal head made by Matsushita Electronics Parts ■, and each heating element resistor had a resistance of about 400 Ω/dot, and the main scanning recording speed was 20 m5ec/1 i.
++e, subscan 3.85 It/mad, platen suppression 1, 4 kg/al.

The test was conducted under two conditions: head input of 0.8 mj/dot, 1, and 6 mj/dot. . In addition, a Macbeth densitometer (RD7514, filter, W-106 black color, W-58 red color) was used for density measurement.

Further, after printing, the heat-sensitive recording materials of Examples 1 and 3 were left at room temperature for one month, and changes in image density were examined.

The results are shown in Table-2.

Table 2 From the results in Tables 1 and 2, the two-color heat-sensitive recording material of the present invention has excellent color separation properties, and when an intermediate layer is provided, the color image of the low-temperature color layer changes over time. It can be seen that it is stable.

Patent applicant Rico Co., Ltd. Representative Patent Attorney Toshiaki Ikeura

Claims (3)

[Claims] (1) A low-temperature coloring layer containing a first leuco dye and a first color developer and which develops color at a low temperature, a 20th ico dye, a second color developer, and the 10th ico dye on a support. and a high-temperature color-forming layer that contains a decoloring agent that prevents color development with the first color developer and that develops a color at a high temperature to a color tone different from that of the low-temperature color-forming layer. In a two-color heat-sensitive recording material having a structure in which the first color developer is laminated so as to be located on the upper layer side with respect to the support, the first color developer is represented by the following general formula (wherein R1 and R2 are each independently hydrogen, A two-color heat-sensitive recording material characterized in that it uses a thiourea derivative represented by: halogen, trifluoromethyl group, or alkyl group having 1 to 4 carbon atoms. (2) The two-color thermosensitive recording material according to claim 1, wherein the low-temperature and high-temperature coloring layers are laminated adjacent to each other. (3) The two-color thermosensitive recording material according to claim 1, wherein the low-temperature and high-temperature coloring layers are laminated via an intermediate layer containing a water-soluble polymer and a filler as main components.