JPS62149480A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material having high sensitivity and less susceptible to fading or blushing of recorded images, by using dimethyl 4-hydroxyphathalate and/or a p-oxybenzoic acid ester derivative in combination with a specified monoether of 4,4'-bisphenolsulfone as a color developer. CONSTITUTION:A combination of dimethyl 4-hydroxyphthalate and/or a p- oxybenzoic acid ester of general formula (I), wherein R1 is a 1-8C alkyl, cycloalkyl or a substd. or unsubstd. aryl or aralkyl, with a monoether compound of 4,4'-bisphenolsulfone of general formula (II), wherein R2 is an alkyl, aryl or aralkyl, is used as a color developer in a thermal recording material utilizing a color forming reaction between a leuco dye and the color developer which are provided on a base. Each of the dimethyl ester and the derivative of general formula (I) has a low melting point and a high color developing capability, and accordingly, it has high heat response characteristics and is excellent in uniformity of the density of developed color images. The monoether compound of general formula (II) has a function of preventing crystallization from taking place at a color forming part, and accordingly, it prevents images from being deteriorated due to fading or blushing.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to heat-sensitive recording materials, and more particularly.

A leuco dye that is colorless or slightly pale at room temperature.

The present invention relates to improvements in heat-sensitive recording materials that utilize the color-forming reaction of the leuco dye with a color developer.

[Prior art]

Recently, various recording materials have been researched and put into practical use in the field of information recording, in line with social demands such as diversification and increase in information, resource conservation, and pollution-free technology.Among them, thermal recording materials (1) A colored image is recorded simply by heating, and no complicated development process is required; (2) relatively fi,! (3) paper is often used as a support; Not only is the cost of the support low, but also the feel of the resulting recorded material is similar to that of plain paper, making it suitable for use in computer output, printers such as calculators, recorders for medical measurements, low and high speeds, etc. It is widely used in the facsimile field, automatic ticket vending machine field, thermal copying field, etc.

The above-mentioned heat-sensitive recording material is produced by applying and drying a heat-sensitive coloring layer solution containing a coloring component capable of causing a coloring reaction when heated on a support such as regular paper 1 synthetic paper or a synthetic resin film. A colored image is recorded on the heat-sensitive recording material thus obtained by heating it with a thermal pen or a thermal head.

Conventional examples of such heat-sensitive recording materials include, for example, Japanese Patent Publication No. 13-4160 or Japanese Patent Publication No. 45-14039.
For example, such conventional heat-sensitive recording materials have low thermal responsiveness and cannot obtain sufficient color density during high-speed recording.

As a method for improving such drawbacks, for example, Japanese Patent Application Laid-Open No. 49-3
No. 4842 discloses acetamide, stearamide, m
-Nitrogen-containing compounds such as nitroaniline and dinitrile phthalate, acetoacetanilide in JP-A-52-106746, and N in JP-A-53-11036.
, N-diphenylamine derivative, benzamide derivative,
The speed can be increased by incorporating carbazole derivatives, alkylated biphenyls and biphenylalkanes in JP-A No. 53-39139, and p-oxybenzoic acid ester derivatives in JP-A-56-144193. , a method for increasing sensitivity is disclosed, and 4-
The use of hydroxyphthalic acid dimethyl ester as a color developer was also known as an effective method.

However, these various color developers still have drawbacks such as fading of the recorded image and whitening of the image area (white powder is generated on the surface).

〔the purpose〕

An object of the present invention is to provide a high-sensitivity thermal recording material that improves the above-mentioned conventional drawbacks, that is, to provide a thermal recording material that is highly sensitive and in which recorded images are less prone to fading or whitening. There is a particular thing.

〔composition〕

According to the present invention, in a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and a color developer, 4-
Hydroxyphthalic acid dimethyl ester and/or a P-oxybenzoic acid ester derivative represented by the following general formula (1) in combination with a 4,4'-bisphenolsulfone monoether compound represented by the following general formula (II). Provided is a heat-sensitive recording material characterized in that:

General formula (1) (In the formula, R1 represents an alkyl J having 1 to 8 carbon atoms, a cycloalkyl group, a substituted or unsubstituted aryl group, or an aralkyl group.) General formula ([I) (In the formula , R2 represents an alkyl group, an aryl group, or an aralkyl group.) As described above, the present invention relates to 4-hydroxyphthalic acid dimethyl ester and l or a P-oxybenzoic acid ester derivative represented by the general formula (1) and a general Its main structure is to use it as a color developer in combination with a monoether compound of 4,4'-bisphenolsulfone represented by the formula (II).P-oxy represented by the general formula (1) Examples of benzoic acid ester derivatives include the following.

(1) Benzyl 4-hydroxybenzoate (2) '4-
Methyl hydroxybenzoate (3) Ethyl 4-hydroxybenzoate (4) Propyl 4-hydroxybenzoate (5) 5ec-butyl 4-hydroxybenzoate (6) Phenyl 4-hydroxybenzoate (7) 4-hydroxybenzoate Tolyl acid (8) Cyclohexyl 4-hydroxybenzoate (9) 4
-Phenylpropyl hydroxybenzoate (10) 4-
Phenethyl hydroxybenzoate (11) P-chlorobenzyl 4-hydroxybenzoate (12) 0-chlorobenzyl 4-hydroxybenzoate (13) ρ-methoxybenzyl 4-hydroxybenzoate (14) 0- 4-hydroxybenzoate Methoxybenzyl et al.

Examples of the monoether compound of 4,4'-bisphenolsulfone represented by the general formula (■) include the following.

(1) 4-hydroxy-4'-methoxydiphenylsulfone (2) 4-hydroxy-4'-ethoxydiphenylsulfone (3) 4-hydroxy-4'-isopropoxydiphenylsulfone (4) 4-hydroxy-4' - n-propoxydiphenylsulfone (5) 4-hydroxy-4'-〇-butoxydiphenylsulfone (6) 4-hydroxy-4'-isobutoxydiphenylsulfone (7) 4-hydroxy-4'-5ec-butoxydiphenylsulfone ( 8) 4-hydroxy-4'-jerbutoxydiphenylsulfone (9) 4-hydroxy-41-benzyloxydiphenylsulfone (10) 4-hydroxy-4'-phenoxydiphenylsulfone (11) 4-hydroxy-4'-( m-methylbenzyloxy)diphenylsulfone (12) 4-hydroxy-4'-(P-methylbenzyloxy)diphenylsulfone (13) 4-hydroxy-4'-(o-methylbenzyloxy)diphenylsulfone (14) 4 -Hydroxy-4'-(P-chlorobenzyloxy)diphenylsulfone, etc.

The 4-hydroxyphthalic acid dimethyl ester and the P-oxybenzoic acid ester derivative represented by the general formula (1) used in the present invention have a low melting point and a high color developing ability. Compared to conventional color developers such as 4,4'-isopropylidene diphenol and 4,4'-butylidene diphenol, it has higher thermal responsiveness and excellent density uniformity of colored images.

Although the monoether compound of 4,4'-bisphenolsulfone represented by the general formula (n) is slightly inferior in thermal response and density uniformity of colored images when used alone, dimethyl 4-hydroxyphthalate has strong color developing ability. ester and/or
Alternatively, when used in combination with a P-oxybenzoic acid ester derivative, it is eutectic and has the function of preventing crystallization in the coloring areas, thereby preventing image deterioration due to fading or whitening of the image area.

In the present invention, the color developer consisting of the above combination is generally used in an amount of 1 to 10 parts by weight, preferably 2 to 6 parts by weight, per 1 part by weight of the leuco dye. Furthermore, a conventionally known phenolic acidic substance can be added as required.

The heat-sensitive recording material of the present invention can have various structures, including all conventionally known structures that utilize a color-forming reaction between a leuco dye and a color developer. For example, the heat-sensitive recording material of the present invention has a structure in which a leuco dye and a color developer are supported on a support as the same coating layer or separate coating layers, or a heat-sensitive recording material in which a leuco dye is supported as a transfer layer. It can be used as a thermal transfer type heat-sensitive recording material consisting of a transfer sheet supported on a body and a receptor sheet supported on a support with a color developer as a receptor layer.

In the case of thermal transfer type thermal recording materials, for the transfer sheet,
A desired colored image can be formed on the receiving layer surface of the receiving sheet by overlapping the receiving sheets so that the receiving layer is in contact with the transfer layer of the transfer sheet and thermally printing from the front or back side of the polymerized sheet 1 to 1. .

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-cimitylaminophthalide (also known as crystal violet lactone), 3.3-bis(p-dimethylaminophenyl)-6-simithylaminophthalide (also known as crystal violet lactone) -dimethylaminophenyl)-6-diethylaminophenyl.

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

3-dimethylamino-5,7-cimitylfluorane.

3-diethylamino-7-chlorofluorane.

3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-(N-ρ-toly-N-ditylamino)- 6-Methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2-(N-(3'-)-chloromethylphenyl)amino)-6-dinithylamino Fluorane, 2- (
3,6-bis(diethylamino)-9-(o-chloroanilino)xantylbenzoic acid lactam), 3-diethylamino-6-methyl-7-(m-trichloromethylanilino)fluoran, 3-diethylamino-7-(0 -chloranilino) fluorane.

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-8'-methoxy-benzoindolino-pyrylospirane, 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-trifluoromethylanilinofluorane.

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-(0-methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7-(α-phenylethylamino)fluorane, 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, 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, methoxy cellulose, 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 /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. are used.

In addition, in the present invention, in addition to the leuco dye and color developer, if necessary, auxiliary additive components 1 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-formalin resin, styrene/methacrylic acid copolymer, polystyrene resin, and other organic fine powders. Examples of thermofusible substances include 1, for example, 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.

Examples include higher linear glycols, dialkyl 3,4-epoxy-hexahydrophthalates, higher ketones, and other heat-fusible organic compounds having a melting point of about 50 to 200°C.

The heat-sensitive recording material of the present invention can be produced, for example, by applying a coating liquid for forming a heat-sensitive layer containing the above-mentioned components onto a suitable support such as paper, synthetic paper, or plastic film, and drying it. applied to the field of recording.

〔effect〕

The heat-sensitive recording material of the present invention comprises 4-hydroxyphthalic acid dimethyl ester and/or a P-oxybenzoic acid ester derivative represented by general formula (I) and 4,4'-bisphenolsulfone represented by general formula (If). Because it uses a combination with a monoether compound as a color developer, compared to conventional products, there is extremely little fading or whitening of recorded images, and it has excellent thermal sensitivity, exhibits high color development, and has high image reliability. It is.

〔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-3-N-cyclohexylamino-6-
Methyl-7-anilinofluorane 300 parts 10% polyvinyl alcohol aqueous solution 300 parts water
400 copies [
Solution B] Dimethyl 4-hydroxyphthalate 150 parts Ester 4-hydroxy-4'-benzyloxydiphenylsulfone 50 parts Calcium carbonate 100 parts 10% polyvinyl alcohol aqueous solution 200 parts Water
450 parts of each of the above compositions were dispersed in a ball mill for 72 hours.
Solution and B solution were obtained, and then 20 parts of A solution and 80 parts of B solution were mixed to prepare a thermosensitive coloring layer forming solution, and this was mixed to a basis weight of 52 g/r.
n' high-quality paper with a wire bar to a weight of 5 g/m after drying, and the surface was smoothed to a smoothness of 700 to 1.
A heat-sensitive recording material of the present invention was prepared by calendering for 200 seconds.

Examples 2 to 4 The same procedure as in Example 1 was carried out except that 4-hydroxydimethyl ester and/or 4-hydroxy-4'-benzyloxydiphenyl sulfone in Solution B of Example 1 was replaced with the compounds shown in Tables LA and B. Thermal recording sheets 1 to 1 of the present invention were prepared.

Comparative Example 1 A comparative heat-sensitive recording sheet was prepared in the same manner as in Example 1, except that 4-hydroxy-4'-benzyloxydiphenyl sulfone in the B solution in Example 1 was omitted.

Comparative Example 2 A heat-sensitive recording material of Comparative Example 1 was obtained in the same manner as in Example 1, except that the [liquid B] in Example 1 was replaced with the following [liquid C].

[Liquid C]

Bisphenol A 150 parts Stearic acid amide 75 parts Calcium carbonate 100 parts 10% polyvinyl alcohol aqueous solution (200 parts water)
Dynamic coloring sensitivity, image fading, and whitening of one image were tested on a heat-sensitive recording material containing 475 parts or more.

The results are shown in Table-1. The test method was performed as follows.

(1) Dynamic color development sensitivity: head power 0.45W using a thermal printing experimental device with a thin film head manufactured by Matsushita Electronic Components Co., Ltd.
/ dot, 1 line recording time 20 m5/flood, scanning density 8 x 3.85 dots/mm, pulse width 0.6.
1.0.1.2.1.4.1.6.1.8.2, 2n+
sec, and check the print density using Macbeth Densitometer RD-
514 (filter-W-106).

(2) Image fading property...For the samples whose dynamic color development sensitivity was measured in (1), those with a print density of 1.0 to 1.2 (this is Do) the density after being left at room temperature for 15 days. (to be measured and designated as D), and the concentration reduction rate was determined according to the following formula.

(3) Image whitening... Perform the same test as (2),
Judgment was made by visual inspection as shown below.

0 Almost no white powder generation Δ White powder is generated, but there is no practical problem X: Not practical due to large amount of white powder generation

Claims (1)

[Claims] (1) In a heat-sensitive recording material that utilizes a color reaction between a Roy dye and a color developer on a support, the color developer is 4-hydroxyphthalic acid dimethyl ester and/or represented by the following general formula (I). 1. A heat-sensitive recording material characterized in that a P-oxybenzoic acid ester derivative is used in combination with a monoether compound of 4,4'-bisphenolsulfone represented by the following general formula (II). General formula (I) ▲There are numerical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1 represents an alkyl group with 1 to 8 carbon atoms, a cycloalkyl group, or a substituted or unsubstituted aryl group or aralkyl group.) General formula (II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_2 represents an alkyl group, an aryl group, or an aralkyl group.)