JPS62270383A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material having high sensitivity and imparting a recording image reduced in fading and whitening, by using at least one kind of a compound represented by a specific formula as a coupler and providing a protective layer on a thermal color forming layer. CONSTITUTION:At least one kind of a compound represented by formula (I) (wherein n is 1 or 2) is used as a coupler utilizing the color forming reaction with a leuco dye and a protective layer based on polyvinyl alcohol, methyl cellulose and a water resistance imparting agent is provided on a thermal color forming layer. As the compound represented by the formula (I), one represented by formula (2) is designated. As the water resistance imparting agent, it is pref. to use a polyamide-epichlorohydrin resin and the mixing wt. ratio of polyvinyl alcohol and methyl cellulose is desirably set to 98:2-60:40. As the leuco dye adapted alone or as a mixture of two or more kinds of ones, for example, leuco compounds of triphenylmethane, fluorane, phenothiazine, auramine and spiropyrane type dyes are pref. used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat-sensitive recording material, and more specifically, the present invention relates to a heat-sensitive recording material, and more specifically, a combination of a leuco dye that is colorless or slightly pale at room temperature, and a color developer that reacts with the leuco dye when heated to develop a color. This paper relates to the improvement of heat-sensitive recording materials using the color-forming reaction between

[Prior art]

Recently, various recording materials have been researched and developed and put into practical use in the information recording field, in response to social demands such as diversification and increase in information, resource conservation, and pollution-free technology.Among them, thermal recording materials are (]) A colored image is recorded simply by heating, eliminating the need for a complicated development process; (2) It can be produced using a relatively simple and compact device; and the resulting recording material is easy to handle. (3) paper is often used as the support;
In this case, not only the support cost is low.

Because of the advantages of the obtained recording material, such as its feel being similar to that of plain paper, it is useful in the fields of computer output, printers such as calculators, recorders for medical measurement, low and high speed facsimiles, automatic ticket vending machines, and thermal copying fields. It is widely used in etc.

The above-mentioned heat-sensitive recording materials are usually manufactured by coating a support such as paper, synthetic paper, or synthetic resin film with a heat-sensitive coloring layer solution containing a coloring component that can cause a coloring reaction when heated, and then drying it. 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. 43-4160 and Japanese Patent Publication No. 43-4160.
The heat-sensitive recording material disclosed in Japanese Patent Publication No. 5-14039 can be mentioned, but such conventional heat-sensitive recording materials have, for example, low thermal responsiveness and cannot obtain sufficient color density during high-speed recording. As a method for improving such drawbacks, for example, JP-A-49-38424 discloses acetamide, stearamide, rhonitroaniline, diphthalate!・Nitrogen-containing compounds such as lyl, acetoacetanilide in JP-A-52-106746, N,N-diphenylamine derivatives, benzamide derivatives, carbazole derivatives in JP-A-53-11036, etc. Kaisho 53-39
No. 139 discloses alkylated biphenyls and biphenylalkanes, and JP-A-56-144193 discloses P-
A method of increasing speed and sensitivity by incorporating oxybenzoic acid ester vl has been disclosed, and among these methods, using ρ-hydroxybenzoic acid ester as a color developer is known as an effective method. It was getting worse.

However, these various color developers still have drawbacks such as fading of recorded images and whitening of image areas (white powder is produced 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, at least one compound represented by the following general formula (I) is used as the color developer, and the heat-sensitive Provided is a heat-sensitive recording material characterized in that a protective layer containing polyvinyl alcohol, methyl cellulose, and a water-resistant agent as main components is provided on the coloring layer.

(In the formula, n represents 1 or 2) As described above, the present invention uses a compound represented by the general formula (1) as a color developer, and a protective layer comprising polyvinyl alcohol, methylcellulose, and a waterproofing agent. The basic structure is that the coloring layer is provided on the heat-sensitive coloring layer.

Examples of the compound represented by the general formula (I) include the following.

In the present invention, polyvinyl alcohol, methyl cellulose, and a waterproofing agent are used as the main components of the protective layer. In this case, commonly used resins can be used as the waterproofing agent, but in particular, Preference is given to using polyamide-epichlorohydrin resins.

In addition, the mixing weight ratio of polyvinyl alcohol and methylcellulose is 98:2 to 60:40, preferably 92:8 to
A ratio of 80:20 is desirable.

Furthermore, in the present invention, an undercoat layer can be provided between the support and the thermosensitive coloring layer, but in this case,
It is preferable to use tetrabromobisphenol S as its main component.

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:
Any dye that has been applied to this type of heat-sensitive material may be used. For example, leuco compounds of dyes such as triphenylmethane, fluoran, phenothiazine, auramine, and spiropyran 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-diethylaminophenyl, 3.3-bis(p-dimethylaminophenyl)-6-chlorophthalide, 3.3-bis(P-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlor Fluoran, 3-dimethylamino-5,7-dimethylfluoran, 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'-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- chloroanilino)fluoran, 3-dibutylamino-7-(0-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)fluorane.

Benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrylosbilane, 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 (21-methoxy-・1'-dimethylaminophenyl)-3- (2'-hydroxy-47-chloro-
5'-Methylphenyl)phthalide, 3-morpholino-7-(N-propyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro- 7-(N-benzyl-1-lifluoromethylanilino)fluorane, 3-pyrrolidino-7-(di-p-chlorophenyl)methylaminofluorane, 3-diethylamino-5-chloro-7-(α-phenyl ethylamino)fluoran, 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-methyl 1-ruinono)-1-(p-
〇-Butylanilino)fluorane, 3-(N-benzyl-N-cyclohexylamino) = 5
．． 6-penzo 7-α-naphthylamino-1'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino 4
',5'-benzofluorane etc.

Further, as other color developers that can be used in combination in the present invention, various electron-accepting substances that react with the leuco dye and develop color when heated are used, and specific examples thereof include:
Examples include the following phenolic substances, inorganic acidic substances, organic acidic substances, and their salts.

Phenolic substances; 3.5-xylenol, thymol, p-tert-butylphenol. 4-Hydroxyphenoxide, methyl-
4-hydroxybenzoate, 4-hydroxyacetophenone, α-naphthol, β-naphthol, catechol 5 resorcinol, hydroquinone, 4-tert-octylcatechol, 4.4-sec-butylidenephenol, 2,2'-dihydroxydiphenyl, 2 , 2-methylenebis(4-methyl-6-tert-butylphenol), 2,2-bis(4-hydroxyphenyl)propane, 4,4-isopropylidene-bis(2-tert-butylphenol), 4,4-see -butylidene diphenol, pyrogallol, phloroglucin, phloroglucin carboxylic acid, 4-tert-octylphenol,
4-phenylphenol, 2.2-bis(P-hydroxyphenyl)butane, 4,4'-cyclohexylidenediphenol, 2.2-bis(2,5-dibromo-4-hydroxyphenyl)propane, 4, 4'-isopropylidene bis(2-tert-butylphenol), 2,2
'-methylenebis(4-chlorophenol), etc.

Acidic substances or salts thereof; benzoic acid, gallic acid, salicylic acid, zinc salicylate, 1
-Hydroxy-2-naphthoic acid, 0-hydroxybenzoic acid, m-hydroxybenzoic acid, benzyl P-hydroxybenzoate, 2-hydroxy-phruyl acid, tartaric acid,
Boric acid, zinc 3,5-di-t-butylsalicylate, 3.
5-di-t-butyltin salicylate, propyl P-hydroxybenzoate, ethyl P-hydroxybenzoate, butyl P-hydroxybenzoate, p-hydroxybenzoic acid-rho
-Chlorbenzyl, P-hydroxyamne, C1 folic acid-0-
Chlorbenzyl, ρ-hydroxybenzyl, low aromatic acid-P-methylbenzyl, ethyl P-hydroxybenzoate, 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, methoxycellulose, hydroxyl, etc. Ethylcellulose.

Cellulose derivatives such as carboxymethylcellulose, methylcellulose, and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic amide/acrylic ester copolymer, acryl amide/acrylic ester/methacrylic acid ternary copolymer, styrene/maleic anhydride Acid copolymer alkali salt, inbutylene/maleic anhydride copolymer alkali salt, polyacrylamide,
In addition to water-soluble polymers such as sodium alginate, gelatin, and casein, polyvinyl acetate, polyurethane, styrene/butadiene copolymer, polyacrylic acid, polyacrylic acid ester, vinyl chloride/vinyl acetate copolymer, and polybutyl methacrylate. Latexes such as ethylene/vinyl acetate copolymers, styrene/butadiene/acrylic copolymers, 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-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-hexahydrophthalates, higher ketones, and other thermofusible organics. Examples include 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 uses a compound represented by general formula (I) as a color developer, and a protective layer containing polyvinyl alcohol, methylcellulose, and a water-resistant agent as main components is provided on the heat-sensitive coloring layer.

Compared to conventional products, recorded images have extremely little fading or whitening, have excellent thermal sensitivity, exhibit high color development, and have high image reliability.

〔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.

[Liquid A]

3-(N-methyl-3-N-cyclohexyl)amino-
6-Methyl-7-anirite fluorane 20
Part 10%-Polyvinyl alcohol aqueous solution 2Qn
water
60〃[Liquid B] 1(()-α5-(C11,)2-0-CI+□-()
(CI2), -3-σOH 20 parts 1 kg polyvinyl alcohol aqueous solution 20 parts water
60/I [Liquid C] 40%-styrene acrylic copolymer resin 25 parts 1
0% polyvinyl alcohol aqueous solution 1OIl Tetrabromobisphenol S 1oll water
551
1 [Liquid D] Calcium carbonate 30 parts 10%
Polyvinyl alcohol aqueous solution 15/! water
55# [H
Liquid] Silica (Fuji Davison Thyroid 244) 2 parts 10% polyvinyl alcohol aqueous solution 3511
5% cellulose aqueous P&I, o+no water 55
rt [H solution] Silica (Fuji Devin Thyroid 244) 2 parts 10% polyvinyl alcohol aqueous solution 38-15
% methylcellulose aqueous solution 14n water
53 parts [Liquid G] Silica (Fuji Davison Thyroid 244) 2 parts loz polyvinyl alcohol aqueous solution 20 5%
Methylcellulose aqueous solution 40I! water
38 mel
[H solution] Silica (Fuji Davison Thyroid 244) 2 parts 10% polyvinyl alcohol aqueous solution 40 Water
58
The mixtures having the above compositions were each ground and dispersed using a sand grinder for 2 hours to prepare solutions A to II.

Example 1 3.0 parts of [liquid A], 10.0 parts of (liquid B) and 3.0 parts of [liquid D] were taken in 11) above and mixed and stirred to obtain a thermosensitive coloring layer forming liquid. . On the other hand, take 40 parts of [Liquid E] and 7 parts of polyamide epichlorohydrin resin,
A protective layer forming liquid was obtained by mixing and stirring.

Next, on top of this commercially available high-quality paper with a basis weight of 52 g/n, the thermosensitive coloring layer forming solution (L!11 cloth M; 16 g/
n? (before drying)) and protective layer forming liquid (coating M; 47
g'' (before drying)) was sequentially coated and dried, and then calendered to a smoothness of 500 to 1200 seconds to prepare a heat-sensitive recording material.

Example 2 Same as Example 1 except that 10 parts of [Liquid C] obtained above was applied as an under layer forming liquid on high-quality paper (coating ffl: lOg/m (before drying)) and an under layer was formed. A heat-sensitive recording material was prepared.

Example 3 A heat-sensitive recording material was produced in the same manner as in Example 2, except that the protective layer forming liquid in Example 2 was changed to [Liquid H].

Example 4 1 of [8 liquids] which is the thermosensitive color forming layer forming liquid in Example 2
to-@-3 machine C11,)2-0-C1l,-0-(C
1+□) Instead of 2-8÷011, +10÷5-CH, -
A heat-sensitive recording material was prepared in the same manner as in Example 2 except that 0-C112-0-C1+2-5÷0[() was used.

Comparative Example 1 Example 1 except that the protective layer forming liquid in Example 1 was removed.
A heat-sensitive recording material was prepared in the same manner as above.

Comparative Example 2 1 of [Liquid B] which is the thermosensitive coloring layer forming liquid in Example 2
10÷5-(C112)2-0-C112-0-(C1
+□) A heat-sensitive recording material was prepared in the same manner as in Example 2, except that benzyl p-hydroxybenzoate was used instead of 2-3-@-01,+.

Comparative Example 3 A heat-sensitive recording material was produced in the same manner as in Example 2, except that [Liquid E] of the protective layer forming liquid in Example 2 was replaced with [Liquid G].

Comparative Example 4 [Liquid E] of the protective layer forming liquid in Example 2 was changed to (Liquid If)
A heat-sensitive recording material was prepared in the same manner as in Example 2, except that .

Next, each of the heat-sensitive recording materials obtained above was tested for dynamic color density, storage stability, oil resistance, plasticizer resistance, and whitening. The results are shown in Table-1. The test method was performed as follows.

(1) Dynamic color density...manufactured by Kensei Electronics Co., Ltd.
Using a thermal printing experimental device with a thin film head, the head gravity was 0.45 W/dot, and the recording time for one line was 20+ns/.
Q. Print with a pulse width of 2.0 m5ec at a scanning line density of 8 x 3.85 dots/square, and measure the print density using a Macbeth densitometer RD-514 (7-1') I, r'1--W-
106)'l! ! Established.

(2) Storage property: A sample printed at 140°C for 1 second at a pressure of 2 kg using a thermal gradient tester (Toyo Seiki Layer) was left at 40°C and 90% RH for 16 hours. After that, Macbeth Densitometer RD-514 (Filter-1#-1
06).

(3) Oil resistance...Cottonseed oil was attached to the sample obtained using a thermal gradient tester, and the sample was dried at 40℃ for 16 hours.
After standing for a period of time, it was measured using a Macbeth densitometer RD-514 (filter-W-106).

(4) Plasticizer resistance...Place one sheet of PVC on the sample obtained with a thermal gradient tester and dry it for 5k at 40℃.
After leaving it for 16 hours under a load of 1.5 g, it was measured using a Macbeth densitometer RD-514 (Filter-1it-1,06).

(5) Whitening: The sample obtained using a thermal gradient tester is immersed in water for 16 hours, then dried at room temperature, and the state of whitening on the image area is ranked. did.

O Almost no whitening △ Slight whitening × Severe bleaching Table-1

Claims (1)

[Claims] (1) In a heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and a color developer, the color developer may be of the following general formula (
1. A heat-sensitive recording material comprising at least one compound represented by I) and a protective layer containing polyvinyl alcohol, methyl cellulose, and a water-resistant agent as main components on the heat-sensitive coloring layer. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, n represents 1 or 2)