JPS61242884A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material having sufficient developed color density and color forming sensitivity, suitable for high-speed recording and having a high ground brightness and extremely high practicality, by using a specified dithioether compound as an auxiliary component, in a thermal recording material utilizing a color forming reaction between a leuco dye and a color developer. CONSTITUTION:A dithioether compound of general formula, wherein R is alkylene, each of X and Y is hydrogen, lower alkyl, alkoxy, aryl, acyloxy, aralkyl or halogen, X and Y may be the same or different, and each of m and n is an integer of 0-3, is used as an auxiliary component, in a thermal recording material utilizing a color forming reaction between a leuco dye and a color developer. The dithioether compound has a high capability of dissolving the color developer and the being heated, and by regulating the melting point of the dithioether compound it is possible to obtain a thermal recording material with an arbitrary sensitivity. The dithioether compound preferably with an arbitrary sensitivity. the dithioether compound preferably has a melting point of 40-150 deg.C from the viewpoints of preservation stability and sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat-sensitive recording material, and particularly to a heat-sensitive recording material with excellent color development.

[Prior art]

General heat-sensitive recording materials are coated on a support such as paper or film, and contain a colorless or light-colored dye such as a leuco dye as a color former, and a phenolic compound (particularly bisphenol A) as a color developer to make the color develop when heated. A heat-sensitive coloring layer in which a binder, a filler, a sensitivity improver, a lubricant, and other auxiliary agents are further dispersed in a coloring system made of an acidic substance such as an organic acid is provided. Kosho 45-14
No. 039 and Japanese Patent Application Laid-Open No. 18-27736, it has been widely put into practical use. This type of thermal recording sheet produces a colored image through an instantaneous chemical reaction between a coloring agent and a color developer during heating (a thermal printer or facsimile machine with a built-in thermal head is used for heating). because there is,
Compared to other recording materials, records can be obtained in a short time using relatively simple equipment without complicated processing such as development and fixing, there is less noise generation and environmental pollution, and the cost is low. Due to the advantages of
It is useful as a recording material for various information such as medical measurement lateral roots and measurement equipment.

On the other hand, in recent years, along with the development of society, there has been an increasing demand for higher speed and higher density recording. For this reason, there is a strong desire not only to increase the speed of the recording apparatus itself, but also to develop recording materials that can handle this. The first method is to lower the melting point of the electron-accepting compound used as the color developer to a practically acceptable level (e.g., 80 to 120°C) and lower the melting point with the leuco dye. The objective is to reduce the speed and speed up the process. However, it is difficult to control the melting point of phenolic compounds, which are color developers that are currently widely used in the field of heat-sensitive recording materials, and the phenolic compounds themselves are expensive, making them impractical. As method 2, for example, as described in JP-A-53-39139, JP-A-53-26139, JP-A-53-5636, JP-A-53-11036, etc.
Various waxes, fatty acid amides, alkylated biphenyls, substituted biphenylalkanes, coumarins,
There is a method of adding a low melting point heat-melting substance such as diphenylamines as a sensitizer (or melting point depressant). However, it cannot be said that the heat-sensitive recording materials produced based on these methods are still sufficient in terms of color density, color sensitivity, background whiteness, etc.

〔the purpose〕

An object of the present invention is to provide a heat-sensitive recording material that has sufficient color density and color sensitivity, is suitable for high-speed recording, has high background whiteness, and is highly practical.

〔composition〕

The heat-sensitive recording material of the present invention is characterized in that it uses a dithioether compound represented by the following general formula (RI) as an auxiliary component in a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and a color developer.

In the formula, R is an alkylene group (usually has 1 to 12 carbon atoms and may have a branched chain), and X and Y are a hydrogen atom, a lower alkyl group, an alkoxy group, an aryl group, an acyloxy group, or an aralkyl group. represents a group or a halogen atom, X and V may be the same or different, and O and n each independently represent an integer of 0 to 3.

The dithioether compound represented by the general formula (1), which is used in combination as an auxiliary component in the present invention, is a color developer (electron-accepting compound) and a leuco dye (electron-donating colorless dye) which are widely used. By adjusting the melting point of the dithioether compound that has a high dissolving ability and is used in combination, a heat-sensitive recording material with arbitrary sensitivity can be obtained. .

The dithioether compound used in the present invention has a melting point of 40 to 150 from the viewpoint of storage stability and sensitivity as a heat-sensitive recording material.
℃ is preferable, and 50 to 120℃ is particularly preferable. Specific examples of the dithioether compound of the present invention are shown below, but the present invention is not limited thereto.

Compound No. Structural formula The leuco dyes used in the present invention can be applied alone or in combination of two or more types, but such leuco dyes include:
Those applied to two types of heat-sensitive materials can be arbitrarily applied. For example, leuco compounds of dyes such as triphenylmethane, fluoran, phenothiazine, auramine, spiropyran, and indolinophthalide are preferably used. It will be done.

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-chlorofluoran, 3-dimethylamino-5,7-dimethylfluoran Oran.

3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-
6-Methyl-7-chlorofluorane, 3-(N-p-tolyl-N-ditylamino)-6-methyl-7-anilinofluorane.

3-pyrrolidino-6-methyl-7-anilinofluorane.

2- (N-(3'-triple omethylphenyl)
amino)-6-dinithylaminofluorane.

2-(3,6-bis(diethylamino)-9-(o-chloroanilino)xantylbenzoic acid lactam), 3-diethylamino-6-methyl-7-chloromethylanilino)fluoran, 3-diethylamino-? -(o-chloroanilino)fluoran, 3-dibutylamino-7-(o-chloroanilino)fluoran, 3-N-methyl-N-isoamylamino-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-8'-methoxy-benzoindolino-pyrylosbilane, 6'-bromo-3'-methoxy-benzoindolino-pyrylospirane, 3-(2'-hydroxy-4'-dimethylaminophenyl) )-3-(2'-methoxy-5'-chlorophenyl) phthalide, 3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-nitrophenyl) phthalide .

3-(2'-hydroxy-4'-diethylaminophenyl)-3-(2'-methoxy-5'-methylphenyl)phthalide, 3-=(2'-methoxy-4'-dimethylaminophenyl)-3- (2'-hydroxy-4'-chloro-5
'-methylphenyl)phthalide, 3-morpholino-7-(N-propyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-tripleomethylanilinofluorane.

3-diethylamino-5-chloro-7-(N-benzyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-(di-p-chlorophenyl)methylaminofluorane, 3-diethylamino-5-chloro- 7-(α-phenylethylamino)fluoran, 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)fluoran.

3-(N-benzyl-N-cyclohexylamino)-5
, 6-Verizo 7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-N-ethyl-N-(2-ethoxypropyl)amino-6 -Methyl-7-anilinofluorane.

3-N-ethyl-N-tetrahydrofurfurylamino-
6-Methyl-7-anilinofluorane.

3-diethylamino-6-methyl-7-mesitidino 4
',5'-benzofluorane etc.

As the color developer used in the present invention, various electron-accepting compounds, such as phenolic compounds, thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof, are preferably used, and the specific examples thereof are as follows. Give an example.

4.4'-isopropylidene bisphenol, 4.4
′ -isopropylidene bis(0-methylphenol)
.

4.4'-Secondary-butylidene bisphenol 4
．． 4'-isopropylidene bis(2-tert-butylphenol), 4.4'-cyclohexylidene diphenol, 4.4
′ -isopropylidene bis(2-chlorophenol)
, 2.2'-methylenebis(4-methyl-6-tert-butylphenol), 2.2'-methylenebis(4-ethyl-6-tert-butylphenol), 4.4'-butylidenebis(6-7art-butyl- 2
methyl)phenol.

4.4'-thiobis(6-tartbutyl-2-methyl)phenol, 4.4'-diphenolsulfone.

4.4'-Diphenol sulfoxide, isopropyl P-hydroxybenzoate, benzyl P-hydroxybenzoate.

benzyl protocatechuate, Stearyl gallate.

Lauryl gallate, octyl gallate, 1,7-bis(4-hydroxyphenylthio)-3,5
-dioxahebutane, 1,5-bis(4-hydroxyphenylthio)-3-oxapentane, 1,3-bis(4-hydroxyphenylthio)-propane.

1.3-bis(4-hydroxyphenylthio)-2-hydroxypropane, N,N'-diphenylthiourea, N,N'-di(-monochlorophenyl)thiourea, salicylanilide, 5-chloro-salicylanilide , salicyl-〇-chloroanilide, 2-hydroxy-3-naphthoic acid.

2-Hydroxy-1-naphthoic acid.

l-hydroxy-2-naphthoic acid, metal salts of hydroxynaphthoic acid such as zinc, aluminum, calcium, etc.

In the present invention, in order to bind and support the leuco dye, color developer and auxiliary components on the support, various conventional binders can be used as appropriate, such as polyvinyl alcohol, starch and its derivatives, methoxy Cellulose derivatives such as cellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic amide/acrylic ester copolymer, acrylic amide/acrylic ester/methacrylic acid ternary copolymer , styrene/maleic anhydride copolymer alkali salt, isobutylene/maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, and other water-soluble polymers, as well as polyvinyl acetate, polyurethane, styrene/butadiene. Copolymer, polyacrylic acid, polyacrylic acid ester, vinyl chloride/
Latex such as vinyl acetate copolymer, polybutyl methacrylate, ethylene/vinyl acetate copolymer, styrene/butadiene/acrylic copolymer, etc. can be used.

In the present invention, in addition to the leuco dye, color developer, and auxiliary components, if necessary, auxiliary additive components commonly used in this type of heat-sensitive recording material, such as fillers, surfactants, thermofusible A sexual substance (or lubricant), etc. can be used in combination. In this case, fillers include 1, 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. ,
Examples include organic fine powders such as urea-formalin resin, styrene/methacrylic acid copolymer, and polystyrene resin.

The heat-sensitive recording material of the present invention can be produced, for example, by applying a coating solution for forming a heat-sensitive layer containing the above-mentioned components onto a suitable support such as synthetic paper or plastic film, and drying it. In this case, the amounts of the leuco dye, color developer, and color development sensitivity enhancer used are 5 to 40% by weight and 20% by weight, respectively.
-60% by weight, 20-60% by weight is suitable.

〔effect〕

The heat-sensitive recording material of the present invention has improved sensitivity, is suitable for high-speed recording, and has a high background whiteness, making it extremely practical.

〔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 [Liquid A] 3-(N-methyl-N-cyclohexyl 20 parts
・10% 20 aqueous solution of amino)-6-methyl-7-anilite fluoran hydroxyethyl cellulose
60〃[Liquid B] Bisphenol A 20 parts 10% of hydroxyethyl cellulose 20〃Aqueous solution water
60〃[Liquid C] 5% aqueous solution of methylcellulose 20〃Water
60〃
[Liquid D] Calcium carbonate 20 parts Methylcellulose 5% aqueous solution 20II Water
60
II Next, add 10 parts of liquid A, 30 parts of liquid B, 30 parts of liquid C, and 2 parts of liquid D.
0 parts and 20 parts of inbutylene-maleic anhydride copolymer
% alkaline aqueous solution to form a thermosensitive coloring layer forming solution, this was coated and dried on high quality paper with a basis weight of 50 g to a dry adhesion of 4 to 5 g/rd to form a thermosensitive coloring layer. After that, the layer surface was further calendered so that the surface smoothness was 500 to 600 seconds to obtain a heat-sensitive recording material (a
)It was created.

Example 2 Thermal recording material (b) was prepared in the same manner as in Example 1 except that the following liquid (E) was used instead of [83 liquid] in Example 1.
It was created.

(E) Liquid p-hydroxybenzoic acid benzyl ester 20 parts 10% aqueous solution of hydroxyethylcellulose 20 parts water
6
0 Example 3 Thermal recording material (C) was prepared in the same manner as in Example 1 except that the following liquid (F) was used instead of liquid (B) in Example 1.
It was created.

[F liquid]

1,7-bis(4-hydroxyphenylthio)-3,5
-Dioxahebutane 20 parts 10% aqueous solution of hydroxyethyl cellulose 20 parts Water
6o Comparative Example 1 Example 1 except that water was used instead of liquid (C) in Example 1.
A thermosensitive recording material (d) was prepared in the same manner as above.

Comparative Example 2 A thermosensitive recording material (e) was prepared in the same manner as in Example 1 except that water was used instead of liquid (C) in Example 1.

Comparative Example 3 A heat-sensitive recording material (f) was prepared in the same manner as in Example 3 except that water was used instead of liquid (C) in Example 3.

Comparative Example 4 A heat-sensitive recording material (g) was prepared in the same manner as in Example 1 except that the following liquid (G) was used instead of liquid C3 in Example 1.

(G) 2 parts of liquid stearamide, 2 parts of 5% aqueous solution of methyl cellulose, 2 parts of water
6 o〃
Comparative Example 5 A heat-sensitive recording material (h) was prepared in the same manner as in Example 2, except that the liquid (G) was used instead of liquid (C) in Example 2.

Comparative Example 6 A thermosensitive recording material (i) was obtained in the same manner as in Example 3, except that the liquid (G) was used instead of the liquid (C) in Example 3.

The heat-sensitive recording materials (a) to (i) obtained as described above are
Using a thermal printing experimental device with a thin film head made by Matsushita Denimo Parts ■, head power was 0.45 M/dot, 1 line recording time was 20 m5 ec/Ω, and scanning line density was 8 x 3.85 dots/-.
The pulse width was set to 1.6.2.0.2.4 (mse) under the conditions of the meal.
c) Print it out and measure the print density using the Macbeth Densitometer RD-
514 (filter W-106). The results are shown in Table-1.

Table 1 Next, heat-sensitive recording materials (a) to (i) were subjected to a 24-hour storage test under dry conditions at 60° C., and changes in skin density were examined. The results are shown in Table-2.

Table 2 Procedures Amendment Written by Mr. Michibe Uga, Commissioner of the Patent Office, July 10, 1985. Display of the case 1985 Patent Application No. 84948 2, Name of the invention Thermal Recording Material 3, Person making the amendment Relationship to the case Patent Applicant Address 1-3-6 Nakamagome, Ota-ku, Tokyo Name
(674) Ricoh Co., Ltd. - Representative Hama 1) Hiro 4, Agent 〒151 Address 1-58-10-5 Yoyogi, Shibuya-ku, Tokyo
Date of amendment order: 6, Number of inventions increased by amendment: 08, Contents of amendment: The following amendments will be made to the specification of the application.

(1) Excerpt from page 20, line 13 [(C) of Example 1]
Same as Example 1 except that water was used instead of liquid.
should be corrected to "Proceed as in Example 2 except that water was used instead of solution (C) in Example 2."

Claims (1)

[Claims] (1) In heat-sensitive recording materials that utilize the color-forming reaction between leuco dyes and their color developers, there are general formulas, ▲mathematical formulas, chemical formulas, tables, etc. as auxiliary components▼ (where R is an alkylene group, and Y represents a hydrogen atom, a lower alkyl group, an alkoxy group, an aryl group, an aralkyl group, an acyloxy group, or a halogen atom, X and Y may be the same or different, and m and n are each independently 0 to
A heat-sensitive recording material characterized in that a dithioether compound represented by: