JPS63267595A - Thermal color-forming recording body - Google Patents

Abstract

PURPOSE:To reinforce an electromagnetic wave in a near infrared part and to enable a long-wave range rays to be also absorbed, by using a color-forming dye of a specific fluorane compound and a cyanobenzoic acid metal salt as a color developer. CONSTITUTION:A color-forming dye of a fluorane compound having an oligoaniline skeletal chain at the 3-position, which is shown by a formula (I), and a color developer of a cyanobenzoic acid metal salt are contained. In the formula (I), X represents hydrogen atom or R3-N-R4, R3 and R4 independently represent hydrogen atom, alkyl, cycloalkyl, phenyl, or benzyl, R1 represents halogen atom or lower alkyl, (m) is an integer 0, 1, or 2, and a ring C represents a benzene ring or a naphthalene ring. When the cyanobenzoic acid metal salt is used for a thermal color-forming recording body, it is contained at 0.1-10pts. wt. to 1pt.wt. of the fluorane compound shown by the formula (I).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermosensitive color-forming recording material that utilizes color development that also absorbs in the near-infrared region of electromagnetic waves.

[Conventional technology]

2. Description of the Related Art With the recent development of both electronics and information management systems, recording/reading devices that are sensitive to electromagnetic waves with wavelengths ranging from the long wavelength portion of visible light to the near-infrared region are increasingly being used.

Therefore, various color-forming dyes have been proposed that are colorless in themselves, but form pigments that absorb electromagnetic waves in this wavelength range by the action of acidic substances. That is, as compounds having such properties, phthalide compounds are disclosed in JP-A-51-121,035 and JP-A-51-12L037.
No., JP 51-121038, TokuyR 1982-11
5,448, JP 55-115,449, JP 55-115.450, JP 55-115,451
No., JP-A-55-115,452, JP-A-55-11
No. 5,456, #Kokai No. 57-167.979, JP-A-58-157,779, JP-A-60-8.564,
It is known from JP-A No. 60-27.589, etc., and thiofluorane compounds are known from JP-A-59-1.
48,695, fluorene-based compounds are known from Japanese Patent Application Laid-open No. 199,757/1982 and European Patent Application No. 124,377.

On the other hand, the present inventors have recently discovered that a fluoran compound having an olibore-phosphorus skeleton as a substituent at the 6-position develops color when exposed to acidic substances, and also absorbs electromagnetic waves in the near-infrared region, so it can be used as a recording medium with a wide range of uses. I discovered that.

[Problem that the invention seeks to solve]

However, in recent years, there has been a growing demand for color-forming recording materials that absorb near-infrared electromagnetic waves more strongly than conventional recording materials, and that also absorb longer wavelengths.

[Means to solve the problem]

Therefore, the present inventors further researched the color forming properties of the previously proposed fluoran compound having an oligoaniline skeleton as a substituent at the 3-position. The color development of the compound from the visible region to the near-infrared region exceeds the electromagnetic absorption region in the near-infrared region, compared to when using a phenolic substance that is commonly used as a color developer for fluoran-based materials. The present invention was completed by discovering that the absorption in the visible region was also stronger.

[Structure of the invention]

Therefore, the present invention provides a heat-sensitive color-forming recording medium containing a fluoran compound color-forming dye having an oligoaniline skeleton silver at the 3-position and a cyanobenzoic acid metal salt color developer.

The fluoran compound color-forming dye having an oligoaniline skeleton silver at the 3-position used in the present invention is disclosed in Japanese Patent Application Laid-Open No. 61-284485 and Japanese Patent Application No. 61-18122, which are related to the invention of the present inventors.
No. 4, No. 61-290579 or No. 1-3014
It has already been proposed in No. 21. In the "oligoaniline skeleton silver" bonded to the 3-position of the fluoran compound, the formulas R3 and R4 each independently represent a hydrogen atom, an alkyl group, a cycloalkyl group, a phenyl group, or a benzyl group, and R5 and R4 are mutually exclusive. may be combined with adjacent nitrogen atoms to form a pyrrolidino group, pyrrolidino group or solfolino group, R2 represents a hydrogen atom, a lower alkyl group, an aryl group or an aralkyl group, and n is 0. is an integer of 1 or 2). The aromatic ring of this oligoaniline skeleton silver may be optionally substituted with 1 to 4 substituents that are the same or different, and such substituents include a halogen atom, a cyano group, an alkyl group, an aryl group, R50
-, R6oco- and their children represent an alkyl group, an aryl group or an aralkyl group, R6 represents an alkyl group, and R7 and R8 each independently represent a hydrogen atom, an alkyl group or an aryl group.

On the other hand, a fluorane compound is represented by the formula (wherein R1 represents a halogen atom or a lower alkyl group, m is an integer of 0.1 or Fi2, and ring C represents a benzene TR or naphthalene ring).

Ring C of the fluoran compound is a halogen atom, an alkyl group,
It may be substituted with substituents such as lower alkoxy, cycloalkyl, benzyl or phenyl.

It goes without saying that when a plurality of R2 and R1 substituents are present in the formulas representing the oligoaniline skeleton silver and fluoran compounds, they may be different from each other.

Therefore, the color-forming dye used in the present invention is It can be expressed as

In addition, the alkyl group in the definition in the above formula is a straight chain or branched alkyl group having 1 to 8 carbon atoms, and the alkyl group of the lower alkyl group and lower alkoxy group is a straight chain 6A alkyl group having 1 to 5 carbon atoms. or a branched alkyl group. A cycloalkyl group is a 5- or 6-membered ring group, a benzyl group and a phenyl group may have an atom, a lower alkyl group, or a lower alkoxy group as a substituent, and an aryl group is a phenyl group or a naphthyl group. groups, which may be substituted with one or more substituents selected from the group consisting of a lower alkyl group, a lower alkoxy group, an amino group optionally substituted with a lower alkyl group, a halogen atom, and a hydroxyl group. good.

The alkylene group in the aralkyl group is an alkylene group which may have a side chain having 1 to 3 carbon atoms, and the phenyl group is selected from the group consisting of a lower alkyl group, a lower alkoxy group, a halogen atom, and a hydroxyl group. It may be substituted with a substituent.

Typical fluoran compound color-forming dyes represented by the general formula K include the following.

5- (4'-dimethylaminophenylamine)-6-
Chlorofluorane, 5-(4'-dimethylaminophenylamino)-7-
Methylfluorane, 3- (4'-dimethylaminophenylamino)-6-
Mef-7-chlorofluorane, 3-(4'-diethylaminophenylamino)-5,7-dichlorofluorane, 3-(4'-diethylaminophenylamino)-6-
Methylfluorane, 3- (4'-diethylaminophenylamino)-7-
Tunylfluorane, 5-(4'-dibutylaminophenylamino)-6,
7-dimethylfluorane, 3-(4'-(N-propylmethylamino)phenylamino]-7-methylfluorane, 3-(4'-(N
-methylethelamino)phenylaminoco-6-methyl-7-chlorofluorane, 3- (4'-phenylaminophenylamino)-6-
Methyl-7-chlorofluorane, S + (4/-(4
//-methoxyphenylamino)phenylamino) -
5,6-benzofluorane, 3-(4'-phenylaminophenylamino)-7-methylfluorane, 3-(4'-(4"-dimethylaminophenylamino)
Phenylamino]-7-methylfluorane, 3-1:4
'-(4"-bilolisinophenyl ε))phenylaminoco-6-methyl-7-chlorofluorane, 3-(4'-(4"-diethylaminophenylamine)
phenylamino) -5,7-dimethylfluorane, 3- (4'-(4''-diethylaminophenylamine)phenylamino) -5,6-benzofluor sec-2, 3- (4'-(4''- N-cyclohexylmethylaminophenylamino)phenylamino)-7-chlorofluorane, 3- (4'-(4''-dibenzylaminophenylamino)phenylaminocou-6-butylfluorane, 3- [4', - N-(4”-dimethylaminophenylamino)-N-benzylaminocophenylamino-2
-Chloro-7-octylfluorane, 3- (4'-(
4''-(4''-phenylaminophenylamino)phenylamino) -6,7-dimethyl-fluorane, 3- (4'-(4''-phenylaminophenylamino)phenylaminoco-6-methyl-7-chlorofluorane, 3 - (4'-(4'-phenylaminophenylamine)phenylaminoco-6-benzylfluorane, 5- (4'-(4''-72nylaminophenylamino)-27-methylphenylaminoco -6-methyl-7
-chlorofluorane, 3-(4'-(4"-(4"'-methyl-phenylamino)-3"-cyanophenylamino)phenylaminoco-6-methelfluorane, 3-(4'-(4" -(4″-phenylaminophenylamino)phenylamino)phenylamino]-7-methyl-fluorane.

By the way, barcodes have recently been used as a means of product production and distribution management, and semiconductor lasers are used in semiconductor laser reading devices that are often used to read and scan barcode markings. Since infrared rays are emitted, markings that absorb visible or near infrared rays in this wavelength range are required. At the same time, in in-storage marking, in order to confirm that color development has been completed, it is desirable that the color development be black, which can be most clearly recognized.

The fluoran compound color-forming dye represented by the general formula [D] develops a black color even with conventional color developers (for example, phenol compounds), and also absorbs near-infrared electromagnetic waves.

However, when a cyanobenzoic acid metal salt is used as a color developer in the present invention 8A, the wavelength range of absorption is significantly expanded to the long wavelength side compared to the case where a conventional color developer is used. This is extremely convenient for recording/reading devices that utilize near-infrared electromagnetic wave absorption.

Cyanobenzoic acid, which is a color developer that has such an effect, includes p-cyanobenzoic acid, m-cyanobenzoic acid, etc., and they contain halogen atoms and lower alkyl groups as substituents. You may do so. The metal salt may be any polyvalent metal salt, and zinc or tin salts are preferred.

When these metal salts of cyanobenzoic acid are used as a thermosensitive color-forming recording material, the usage ratio is 0.1 to 10 parts by weight of the metal salt of cyanobenzoic acid per 1 part by weight of the fluoran compound represented by the general formula CI). Preferably, the amount of the former is 1 to 5 parts by weight per 1 part by weight of the latter.

The cyanobenzoic acid metal salts in the present invention can be used not only alone, but also in combination, or in combination with commonly used color developers.

Typical common color developers that can be used in combination include bisphenol A, p-hydroxybenzoic acid, 4-hydroxy-4'-di-propoxydiphenyl sulfone, 4-hydroxy-4 '-n
Examples include, but are not limited to, -7'toxy di-phenyl sulfone and his(p-hydroxy7enylthioethoxy)-methylene.

It goes without saying that the fluoran compound represented by the general formula can be used alone, but it is also possible to use a mixture of these compounds (6t). It is also possible to mix and use color-forming dyes that also absorb in the near-infrared region during the color development described.

The method for producing heat-sensitive recording paper using the fluoran compound represented by the general formula is the same as that for known color-forming dyes.
It can be produced according to the method described in Japanese Patent Publication No. 43-4160, Japanese Patent Publication No. 45-14039, or Japanese Patent Application Laid-open No. 7087-1987.

That is, for example, a dispersion in which fine particles of the fluoran compound of the present invention or a mixture of it and another color-forming dye and fine particles of a color developer are dispersed in an aqueous solution of a water-soluble binder is applied to paper. By drying, a thermosensitive recording paper with excellent color development can be obtained. If necessary, a sensitizer can be added to the dispersion, and in this case, a heat-sensitive recording paper with extremely high sensitivity can be obtained.

Typical sensitizers include, but are not limited to, higher fatty acid amides, acetoacetanilide, dibenzyl terephthalate, dibenzyl isophthalate, 4+4'-dimethoxydiphenyl sulfone, and diphenylamine. isn't it. The dispersion may further contain fillers, dispersants, color image stabilizers, antioxidants, desensitizers, antiblocking agents, antifoaming agents, light stabilizers, fluorescent brighteners, etc. .

Recording paper produced according to these methods can be provided with a protective layer on its surface, if necessary, and an adhesive layer on its back surface to facilitate use as a label.

Recording materials manufactured according to these methods are used for copying books, documents, etc., electronic computers, facsimile machines, bar codes, ticket vending machines, labels, etc. In addition, the recording materials manufactured according to these methods are used for copying books, documents, etc., electronic computers, facsimile machines, bar codes, ticket vending machines, labels, etc. In addition, information input with high density, for example, cannot be recorded with the naked eye. It can be applied to a wide range of applications such as anti-counterfeiting, anti-copying, unlocking devices, and laser discs where the information is unknown.

〔Effect of the invention〕

The fluoran compound represented by the general formula (1) absorbs near-infrared electromagnetic waves even in heat-sensitive color recording materials that are combined with commonly used acidic color developers, but cyanobenzoic acid metal salts and The thermosensitive color-forming material of the present invention consisting of the above-mentioned combination expands the absorption wavelength range in the near-infrared region and strengthens the absorption as well as the recording material of the above-mentioned combination.

Therefore, Table 1 below compares the effects of electromagnetic wave absorption in the near-infrared region when bisphenol A is used as the acidic color developer and p-cyanobenzoic acid zinc salt is used as the cyanobenzoic acid metal salt. I feel sorry for that.

These are the results obtained in Examples 1 and 2 and Comparative Examples 1 and 2, and the fluoran compound represented by the general formula [0] is 3-(4'-(4''-phenylaminophenylamino) Phenylaminoco-6-methyl-7-chlorofluorane (used in Example 1 and Comparative Example 1) and 3-(4'-(4"-dimethylaminophenylamino)phenylamino]-7-methylfluorane (Example 2
(used in Comparative Example 2) was used as a precaution.

Table 1 (Example 1) Coloring part 10.5 14.9 21.1
36.1 65.2 Thermal recording paper ■Uncolored area 95.7
97.2 98.8 99.1 98.7 (Comparative Example 1) Coloring part 13.5 23.7 35.9 57.2
78.0 Thermal recording paper ■Uncolored area 8B5 92.2
95.7 95.4 94.3 (Example 2) Coloring part 8.4 12.3 1B, 1 32.1 57.
6 In Table 1, the smaller the reflectance value, the greater the absorption of electromagnetic waves, and the larger the difference in reflectance between the uncolored area and the colored area, the easier it is to read marks, etc. It's easy.

That is, the heat-sensitive color-forming recording material comprising the combination of the fluoran compound represented by the general formula 0] and the cyanobenzoic acid metal salt of the present invention is more effective for the purpose of utilizing electromagnetic wave absorption in the near-infrared region. It shows that something is true.

〔Example〕

Next, details with examples! ! ! However, the present invention is not limited thereto.

(Preparation of coating liquid) Dispersion liquid A type (color former) Compound 1 3-(4'-(4''-phenylaminophenylamino)
Phenylaminoco-6-methyl-7-chlorofluoran compound 2 5-[4'-(4"-dimethylaminophenylamino)phenylamino]-7-methylfluoran compound 3 3-(4'-(4" -Phenylaminophenylami/)
phenylamino) -6,7-dimethylfluorane compound 4 3- (4'-phenylaminophenylamino) -6-
Methyl-7-chlorofluoran compound 5 5-(4'-dimethylaminophenylamino)-6-methyl-7-chlorofluoran composition compound (9 is 5 for 1,2,6,4) 7.
Of clay ii, 5r15
% polyvinyl alcohol aqueous solution 41.5 f water
40. Five types of dispersions having the above compositions were prepared using Or compounds 1 to 5. These are respectively referred to as dispersions A-1, A-2, A-3, A-4 and A-5.

Dispersion liquid type B (color developer) Color developer dispersion liquid B-1, B-2, B-3, B with the composition shown in the following table
-4 and B-5 were prepared.

B-I B-2B-3 p-cyanobenzoic acid zinc salt 10.5 -
-m-cyanobenzoic acid zinc salt -10
,5-bisphenol A
Io, 5 clay
8.0 8.0 8.015% polyvinyl alcohol aqueous solution 41.5 41.5 41.5 Water
40.0 40.0 40
．． 0 (□□□ units) Dispersions A-class liquids and B@ liquids were prepared by mixing the mixtures of their respective compositions with glass beads (diameter 1-1.5 cm) 150 f
Put it in a polyethylene bottle with Red Dev and seal it tightly.
It was ground for several hours using an i1 company H paint conditioner.

Color former crude liquid A and color developer dispersion B were mixed in a ratio of 1 part by weight of the former to 2 parts by weight of the latter to prepare a coating liquid.

Example 1 Thermal recording paper I was manufactured by applying a coating liquid consisting of the dispersions A-1 and B-1 onto a white base paper and dry-printing the same. Using a dry heat tester (manufactured by Kishino Kagaku Kikai Co., Ltd.), this thermosensitive recording paper (2) was heated on both sides for 5 seconds at a temperature of 220° C., which is the saturation color development temperature, to develop color. This developed color tone was dull to black.

The reflectance (700, 780, 830, 900 and 10100) of the uncolored area and colored area of this thermal recording paper I
0n was measured.

For the measurement, a spectrophotometer needle (manufactured by Hitachi, model U-3400 and its attached integrating sphere) was used. This reflection/absorption curve is shown in FIG. 1, and these reflectances are shown in Table 1 together with Comparative Example 1.

゛ Comparative Example 1 Applying a coating liquid consisting of the dispersions A-1 and B-3,
A thermosensitive recording paper (2) was produced in the same manner as in Example 1. Further, in the same manner as in Example 1, color was developed by heating at a temperature of 150° C., which is the saturated color development temperature, and the reflectance of the uncolored area and the colored area was measured.

The developed color tone was black.

These reflectances are shown in Table 1 together with Example 1.

Example 2 Applying a coating liquid consisting of the dispersions A-2 and B-1,
Thermal recording paper (2) was produced in the same manner as in Example 1.

Further, color was developed by heating in the same manner as in Example 1, and the reflectance of the uncolored area and the colored area was measured. The developed color tone was black.

These reflectances are shown in Table 1 together with Comparative Example 2.

Comparative Example 2 A coating solution consisting of the dispersions A-2 and B-3 was prepared, and heat-sensitive recording paper (2) was produced in the same manner as in Example 1. Furthermore, color was developed by heating in the same manner as in Comparative Example 2, and the reflectance of the uncolored area and the colored area was measured.

The color tone developed was black.

These reflectances are shown in Table 1 together with Example 2.
Thermal recording paper V was produced in the same manner as in Example 1.

Further, color was developed by heating in the same manner as in Example 1, and the reflectance of the uncolored area and the colored area was measured. The color tone of this color development was black.

These reflectances are shown in Table 2.

Example 4 A coating solution consisting of the dispersion A-4 and B-1 was prepared,
Thermal recording paper (2) was produced in the same manner as in Example 1.

Further, color was developed by heating in the same manner as in Example 1, and the reflectance of the uncolored area and the colored area was measured. The color tone of this color development was black.

These reflectances are shown in Table 2.

Example 5 A coating liquid consisting of the above-mentioned dispersion liquid A-5 and B-2 was used.
Thermal recording paper (2) was produced in the same manner as in Example 1.

Further, color was developed by heating in the same manner as in Example 1, and the reflectance of the uncolored area and the colored area was measured. The color tone of this color development was black.

These reflectances are shown in Table 2.

Table 2 (Example 3) Coloring part 8.0 13.5 22.4
43.5 77.1 Thermal recording paper ■Uncolored area 96.2
98.3 99.0 99.9 100 (8 cases 4) Coloring part 9.9 20.9 37.4 7CL3 96.
3 Heat-sensitive recording paper ■Uncolored area 90.3 95.7 97.
7 100 100 (Example 5) Coloring part 10. (51
9,231,561,795,9 As shown in Table 1, the lower the reflectance, the stronger the absorption of electromagnetic waves. In Table 2, the thermosensitive recording paper ", ■, and ■ indicate that it strongly absorbs electromagnetic waves in the near-infrared region and is useful as a thermosensitive color-forming recording material.

Claims (1)

[Claims] A heat-sensitive color-forming recording material containing a fluoran compound color-forming dye having an oligoaniline skeleton chain at the 3-position and a cyanobenzoic acid metal salt color developer.