JPH0419183A - Color forming recording material - Google Patents

Abstract

PURPOSE:To perform pressure-sensitive and thermal recording forming a black color enhanced in the fastness against NOx by using a fluorane compound having a specific structure. CONSTITUTION:In a color forming recording material using the color forming reaction of an electron donating leuco dye and an electron acceptive developer, as the electron donating leuco dye, a fluorane compound represented by general formula (I) (wherein R1 and R2 are respectively a methyl group or an ethyl group is used. In this fluorane compound, the nitrogen atom of the anilino group at a 2-position is substituted with a methyl group or an ethyl group and the 3, 4-positions of the anilino group are substituted with a chlorine atom. By the use of this compound, the fastness against NOx is drastically enhanced and a deep-black color can be developed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a black-forming color-forming recording material that has high fastness to NOx.

[Prior Art] Background whiteness is a performance required for color-forming recording materials such as pressure-sensitive and heat-sensitive recording materials that use electron-donating colorless dyes (hereinafter abbreviated as colorless dyes) and electron-accepting color developers. The storage stability of uncolored areas is good, and the fastness of colored images (light resistance, water resistance, heat resistance, heat and humidity resistance, plasticizer resistance) is high. Prior art in pursuit of colorless dyes with these properties include JP-A No. 47-34422;
There are Japanese Patent Application Laid-open No. 5325108, Japanese Patent Publication No. 56-52759, etc.

However, recently, in addition to the above-mentioned performances, stability against NOx (nitrogen oxides) has been required. In other words, the color image of pressure-sensitive/thermal recording materials, etc.
Phenomena such as red discoloration have become a problem. but,
There are very few recording materials currently in practical use that are stable against NOx, and are not in a satisfactory state.

[Problems to be Solved by the Invention] The present inventors use a fluoran compound in which a methyl group or ethyl group is introduced into the nitrogen radical of the anilino group at the 2-position of the fluoran skeleton as a colorless dye in a color-forming recording material. It has been discovered that this improves the fastness to NOx, but many of these fluoran compounds usually develop a reddish or greenish color when reacted with a color developer. Therefore, as a result of further intensive research, we found that by using a fluoran compound having the specific structure (I),
We succeeded in obtaining color-forming recording materials such as pressure-sensitive and heat-sensitive recording materials that are black-colored and have high x-fastness.

[Means for Solving the Problems] The present invention provides a color-forming recording material that utilizes a color-forming reaction between an electron-donating colorless dye and an electron-accepting color developer, wherein the electron-donating colorless dye has the general formula (I). ＼ (I) (In the formula, R and R2 each represent a methyl group or an ethyl group.) By using a fluoran compound represented by
The object of the present invention is to provide a color-developing recording material that has high fastness to water and develops a true black color.

The fluoran compounds used as colorless dyes in the present invention include 2-(N-(3,4-dichlorophenyl)-N
-methylamino] -6-dimethylaminofluorane,
2-(N-(3,4-dichlorophenyl)-N-methylamino)-6-dinithylaminofluorane, 2-
(N-(3,4-dichlorophenyl)-N-ditylamino) -6-dimethylaminofluorane, 2-
[N-(3,4-dichlorophenyl)-N-ethylamino]-6-dinithylaminofluorane.

The fluoran compound represented by the general formula (I) can generally be produced by the following synthesis method.

It is produced by condensing compounds represented by the following general formulas (II) and (III) using a dehydration condensation agent such as concentrated sulfuric acid, and then treating with an alkaline aqueous solution such as caustic soda.

(In the formula, R1 and R2 are the same as above, and R3 is an alkyl group.) Compound (m) is a compound represented by general formula (IV) and RX, (R20) 3P0° (R) So
(In the formula, R2 is the same as above, and X is a halogen atom.) It can be synthesized by reacting with a compound represented by the formula.

In order to use the fluoran compound represented by the general formula (I) as a pressure-sensitive recording material, known methods such as Japanese Patent Publication No. 48-4
No. 3296 etc. can be applied, but for boat fishing, after dissolving the colorless dye Compound (I) in an organic solvent, it can be encapsulated in various ways such as coacervation method, interfacial polymerization method, in-5 itu method, etc. The material is microencapsulated by a method and coated on the back side of a support to create a top paper. When using the fluoran compound represented by the general formula (I) as a colorless dye, it is also possible to use it in combination with other color-forming substances. On the other hand, create a bottom paper with a color developer coated on the surface of another support, and stack the top paper and bottom paper so that the coated surfaces are in contact with each other. (Sometimes several pieces of inner paper with coloring agent microcapsules coated on the underside are sandwiched between them.)

By applying pressure such as writing pressure or striking pressure to this pressure-sensitive recording paper,
The microcapsules are destroyed and the colorless dye inside the capsules reacts with the color developer to obtain a duplicate image. All known color developers for pressure-sensitive recording materials can be used in this pressure-sensitive recording method, such as acid clay, salicylic acid derivative Zn salt, p-octylphenol (POP) resin, etc. , pop resin-zn salt, p-phenylphenol (P
P P) resins, etc. can be mentioned.

In addition, for use in heat-sensitive recording materials, known methods for producing heat-sensitive recording materials, such as the method disclosed in Japanese Patent Publication No. 14039/1982, may be applied as is, but generally fluorinated It is made by coating a compound, a color developer, a sensitizer, and an additive in the form of fine particles with a diameter of several microns in a binder. Upon heating, the fluoran compound represented by the general formula (I) rapidly develops color through a color reaction with a color developer to obtain an image. When using the fluoran compound represented by the general formula (1) as a colorless dye in a heat-sensitive recording material, it is also possible to use it in combination with other color-forming substances. All known color developers used as heat-sensitive recording materials can be used, but for example, p
-octylphenol, p-tert, -butylphenol, p-phenylphenol, 1,1-bis(p-
hydroxyphenyl)propane, 2,2-bis(p-hydroxyphenyl)propane, 1,1-bis(p-hydroxyphenyl)cyclohexane, 2,2-bis(p-
hydroxyphenyl)-4-methylpentane, bis(p
-hydroxyphenyl)sulfone, bis(3-allyl-
Phenol compounds such as 4-hydroxyphenyl) sulfone, bis(p-hydroxyphenyl) sulfide, 1,5-bis(p-hydroxyphenylmercapto)-3-oxapentane, benzyl p-hydroxybenzoate,
Aromatic carboxylic acid derivatives such as ethyl p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, 3,5-di-tert,-butylsalicylic acid, 3.5-di-α-methylbenzylsalicylic acid, phenylthiourea, 4.4 −
Examples include phenylthiourea compounds such as bis(ethylphenyl)thiourea.

As a binder, water-soluble compounds such as methylcellulose, hydroxyethylcellulose, polyvinyl alcohol, carboxy group-modified polyvinyl alcohol, isobutylene/maleic anhydride copolymer alkali salt, and non-water-soluble compounds such as polyvinyl acetate and styrene/butadiene copolymer can be used. Examples include sex emulsions.

Examples of additives include fillers such as calcium carbonate, silica, titanium oxide, aluminum hydroxide, clay, talc, polystyrene resin, and urea-formalin resin, and lubricants such as zinc stearate, calcium stearate, and aluminum stearate.

Examples of the sensitizer include various waxes, aliphatic amides, alkylated biphenyls, substituted biphenyl alkanes, coumarin compounds, diphenylamines, benzyloxynaphthalene, etc., and all of the so-called conventional sensitizers can be used. .

In order to use the fluoran compound of the general formula (I) in an electrically conductive thermal paper, it can be produced, for example, by the method described in JP-A-49-11344.

The fluoran compound represented by the formula (I) used as a colorless dye in the present invention has a methyl group or an ethyl group at the nitrogen atom of the anilino group at the 2-position, and a 3-,
It is characterized by a chlorine atom being substituted at the 4-position,
As a result, we succeeded in dramatically increasing the fastness to NOx and developing a true black color. Structures in which no substituent is introduced into the nitrogen atom of the anilino group have low fastness to NOx. Furthermore, even if a substituent is introduced to the nitrogen atom of the anilino group, a structure in which the anilino group is not substituted with a chlorine atom develops a greenish color and has low practicality. The fastness to NOx is further improved by substituting a chlorine atom to the anilino group, but a compound in which a substituent is introduced to the nitrogen atom of the anilino group and one chlorine atom is substituted to the anilino group, or A substituent is introduced to the nitrogen atom of the anilino group, and 2,3
A compound in which a chlorine atom is introduced at the -position or the 2,4-position also develops a greenish color. A substituent is introduced to the nitrogen atom of the anilino group, and the 2.6-position, 2-position of the anilino group
．． Compounds in which chlorine atoms are introduced at the 5-position, 3, and 5-position develop a reddish color, and are also of low practicality. Only the compound represented by the formula (I) used in the present invention is effective against NOx.
This structure provides a color-forming recording material that satisfies both fastness and color hue.

[Examples] The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples.

Synthesis Example 1 2-(N-(3,4-dichlorophenyl)-N-
Synthesis of -6-dimethylaminofluorane (compound 1) 14.3 g of 2-(2-hydroxy-4-dimethylaminobenzoyl)benzoic acid was added to 75 g of concentrated sulfuric acid at 20 to 30°C.
After dissolving in , 3,4-dichloro-4'-methoxy-N-
14.1 g of methyldiphenylamine was dissolved at 10 to 15°C and stirred at room temperature for 48 hours. After the reaction was completed, the reaction mixture was poured into 500 ml of ice water, and the precipitate was collected by filtration and washed with water. Add 75g of 20% caustic soda aqueous solution to this filter cake.
and 200 ml of toluene were added, and the mixture was stirred under reflux for 1 hour. The toluene layer was separated, washed with hot water, filtered while hot, and the toluene was distilled off. 200 ml of methanol was added to the residue, refluxed with stirring, and then cooled. The precipitate was collected by filtration and dried. Melting point 207.0
14.3 g of white powder of ~208.0°C was obtained. This powder was identified as 2-[N-(8,4-dichlorophenyl)-N-methylamino]-6-dimethylaminofluorane based on elemental analysis.

Elemental analysis value calculation value 0%: 67.31 11%: 4.29 N%
: 5.42 Actual value 0%: 67.23 11%: 4.
29 N%: 5.35 Synthesis Example 2 Synthesis of 2-[N-(3,4-dichlorophenyl)-N-ethylamino]-6-dimethylaminofluorane (compound 2) 2-(2 -Hydroxy-4-dimethylaminobenzoyl)benzoic acid 14.3g at 20-30℃
After dissolving in , 3,4-dichloro-4'-methoxy-N~
14.8 g of ethyl diphenylamine was dissolved at 10 to 15°C and stirred at room temperature for 48 hours. Post-processed in the same manner as in Synthesis Example 1 to obtain white powder 17. with a melting point of 218.5-220°C.
4g was obtained. Based on the elemental analysis value, this powder is 2 [N - (3
,4-dichlorophenyl)-N-ethylamino] -6
-Identified as dimethylaminofluorane.

Calculated elemental analysis value 0%: 87.79 1%: 4.58 N%:
5.27 Actual value 0%: 67.95 11%: 4.5
7 N%: 5.31 Synthesis Example 3 Synthesis of 2-(N-(3,4-dichlorophenyl)-N-methylamino)-6-dinithylaminofluorane (Compound 3) 2-(2- -Hydroxy-4-diethylaminobenzoyl)benzoic acid 15.7 g
After dissolving at °C, 3,4-dichloro-4'-methoxy-N
-14.1 g of methyldiphenylamine was dissolved at 10 to 15°C and stirred at room temperature for 48 hours. Synthesis Example 1 and [N
~(3,4-dichlorophenyl)-N-methylamino]
It was identified as -6-dinithylaminofluoran.

Elemental analysis value calculation value 0%: 68.25 1+%: 4.81 N%
: 5.14 Actual value 0%: 68.36 1%: 4.7
9 N%: 5.19 Synthesis Example 4 Synthesis of 2-(N-(3,4-dichlorophenyl)-N-ethylamino)-6-dinithylaminofluorane (Compound 4) 2-(2- -Hydroxy-4-diethylaminobenzoyl)benzoic acid 15.7g at 20-30℃
After dissolving in 3,4-dichloro-4'-methoxy-N-
14.8 g of ethyl diphenylamine was dissolved at 10 to 15°C and stirred at room temperature for 48 hours. After treatment in the same manner as in Synthesis Example 1, 19.6 g of white powder with a melting point of 199.0 to 201.0"C was obtained. This powder had a 2-
It was identified as (N-(3,4-dichlorophenyl)-N-ethylamino)-6-dinithylaminofluoran.

Calculated elemental analysis value 0%: 68.69 8%: 5.05 N%:
5.01 Actual value 0%: 88.85 8%: 5. O3
N%: 4.99 Example 1 Preparation of pressure-sensitive recording paper 2- [N-(3,4-dichlorophenyl)-N-methylamino] -3 g of 6-dimethylaminofluorane (compound 1) was added to Hysol SA. It was dissolved in 47 g of S-296 (manufactured by Nippon Oil) to obtain a colorless dye solution.

Separately, 5 g of a system modifier was added to too much water, adjusted to pH 4 with a caustic soda solution, and while stirring with a homogenizer, 10 g of urea/melasin polymer (degree of polymerization 300) was added.
A solution of 5 g of water was added slowly. Further, the colorless dye solution was added thereto, and the stirring speed was increased to emulsify for 10 minutes. The temperature was raised to 60° C. over a further 30 minutes and maintained for 1 hour with slow stirring. Next, the mixture was cooled in an ice water bath, and 5 drops of 25% aqueous ammonia were added to adjust the pH to 7.5, followed by stirring for 5 minutes to obtain a microcapsule dispersion. Add 2.2 JP of wheat flour and 1.3 g of latex as a stilting agent to 10 g of this microcapsule dispersion,
The mixture was thoroughly mixed, applied to high-quality paper, and dried to create top paper.

The coated surfaces of this upper paper were brought into close contact with paper coated with a color developer (lower paper), and the entire surface was rolled to develop color using a mini roll. The fastness to NOx of this colored recorded image was determined by the following test method.

[Test method for fastness to NOx] The fastness to NOx test of recording paper using the fluoran compound represented by the general formula (I) as a colorless dye is based on JIS L 0, which exposes a colored image to NOx as a test method.
The method described in 855 was used. The strength of fastness to NOx is determined by the colored image NOxII! ! The hue change before and after dew was determined by measuring with a color difference meter (Tokyo Juishiki TC-PI [)]. The results are shown in Table 1.

Example 2 As a colorless dye, 2-[N-(3.4
-dichlorophenyl)-N-methylamino] -2-[N-(3
,4-dichlorophenyl)-N-ethylamino] -6
A pressure-sensitive paper was prepared in the same manner as in Example 1 except that -dimethylaminofluorane (compound 2) was used, and the fastness to NOx was tested.

The results are shown in Table 1.

Example 3 As a colorless dye, 2-[N-(3,4
-dichlorophenyl)-N-methylamino] -2-[N-(
3,4-dichlorophenyl)-N-methylamino] -
A pressure-sensitive paper was prepared in the same manner as in Example 1 except that 6-ethylaminofluorane (compound 3) was used, and a test for fastness to NOx was conducted.

The results are shown in Table 1.

Example 4 2-[N(3,4-
dichlorophenyl)-N-methylamino] -2-[N-(3,
4-dichlorophenyl)-N-ethylamino] -6-
A pressure-sensitive paper was prepared in the same manner as in Example 1 except that dinithylaminofluorane (compound 4) was used, and a test for fastness to NOx was conducted.

The results are shown in Table 1.

Comparative Example 1 2-[N-(3,4
-dichlorophenyl)-N-methylamino] -2-[N-(3
,4-dichlorophenyl)aminoco6-ethylaminofluorane (Compound 5) was used, but a pressure-sensitive paper was prepared in the same manner as in Example 1, and the fastness to NOx was tested. The results are shown in Table 1.

Comparative Example 2 As a colorless dye, 2-[N(3,4-
dichlorophenyl)-N-methylamino]-2-[N-(3-
A pressure-sensitive paper was prepared in the same manner as in Example 1 except that trifluoromethylphenyl)amino-6-dinithylaminofluorane (Compound 6) was used, and the fastness to NOx was tested.

The results are shown in Table 1.

Comparative Example 3 As a colorless dye, 2-(N-(3,4
-dichlorophenyl)-N-methylamino] -2-[N-(
2,4-dimethylphenyl)aminoco3-methyl-6-
A pressure-sensitive paper was prepared in the same manner as in Example 1 except that dinithylaminofluorane (compound 7) was used, and a test for fastness to NOx was conducted.

The results are shown in Table 1.

Table 1 Explanation of judgment value of NOx fastness test results for pressure-sensitive recording paper In the above measurement, Δa represents reddish dust, Δa=l
a (after exposure) - a (before exposure) When the a value is positive, it shows a reddish tinge, and when it is negative, it shows a greenish tinge.

In determining the fastness to NOx, the larger Δa is, the lower the fastness to NOx is, and the smaller Δa is, the higher the fastness to NOx is.

Reference Example 1 Coloring hue of the compound of the present invention and similar compounds The melting points and coloring hues of the fluoran compound of the present invention and similar fluoran compounds on silica gel are shown in Table 2 below.

Example 5 Preparation of thermal recording paper Preparation of liquid A (colorless dye dispersion) 2-CN-(3,4-dichlorophenyl)-N-methylamino-6-dimethylaminofluorane (compound 1) 3 g, 5% 30g of polyvinyl alcohol aqueous solution,
A mixture of 42 g of water was ground with a sand grinder until the average particle size became IIjJn.

Adjustment of liquid B (developer, sensitizer dispersion) 3 g of bisphenol A, 3 g of p-benzylbiphenyl
A mixture of 7.5 g of calcium 1 carbonate, 15 g of a 5% polyvinyl alcohol aqueous solution, and 48.5 g of water was ground with a sand grinder until the average particle size was 1 μm.

A heat-sensitive coating liquid was prepared by mixing liquid A: liquid B at a ratio of 1:2. This heat-sensitive coating liquid was coated on high-quality paper (basis weight 50 g/g) so that the coated amount after drying was 9.6 g/rrr and dried to obtain heat-sensitive recording paper.

This heat-sensitive recording paper was calendered to have a smoothness of 50.
0 to 600 seconds, Toshiba facsimile C0PIX
Color was developed using TF-370. This colored image was true black and showed good fastness to NOx.

Example 6 2-[N-(
3,4-dichlorophenyl)-N-methylamino] -
2-[N instead of 6-dimethylaminofluorane
-(3,4-dichlorophenyl)-N-ethylamino]
A thermosensitive recording paper was obtained in the same manner as in Example 5 except that -6-dimethylaminofluorane (compound 2) was used, and this was colored. This colored image is true black and has good anti-NO
x fastness.

Example 7 2(N-(3) used as colorless dye in Example 5
,4-dichlorophenyl)-N-methylamino] -6
-2-[N- instead of -dimethylaminofluorane
(3,4-dichlorophenyl)-N-methylamino]
A thermosensitive recording paper was obtained in the same manner as in Example 5 except that -6-ethylaminofluorane (compound 3) was used, and this was colored. This colored image is true black and has good NOx resistance.
It showed fastness.

Example 8 2-[:N − used as colorless dye in Run N5
(3,4-dichlorophenyl)-N-methylamino]
-2-[ instead of -6-dimethylaminofluorane
A thermosensitive recording paper was obtained in the same manner as in Example 5 except that N-(3,4-dichlorophenyl)-N-ethylamino]-6-ethylaminofluorane (compound 4) was used, and this was colored. . This colored image is true black and has a good contrast with N.
Ox fastness was shown.

Structure of the compound of formula (I) of the present invention (Compound 1) (Compound 2) (Compound 3) Structure of the comparative compound (Compound 5) (Compound 4) (Compound 6) (Compound 7) (Compound 10) (Compound 8 ) (Compound 11) (Compound 9) (Compound 12) (Compound 13) Procedural Amendment June 27, 1990 1, Indication of Case 1990 Patent Application No. 1 24641 2, Name of Invention Chromogenic Recording Material By using this, it is possible to obtain a color-forming recording material that has high fastness to NOx and develops a true black color.

Claims (3)

[Claims] (1) In color-forming recording materials that utilize the color-forming reaction between an electron-donating colorless dye and an electron-accepting color developer, the electron-donating colorless dye has the general formula (I) ▲Mathematical formula, chemical formula, table, etc.▼ (I) (In the formula, R_1 and R_2 each represent a methyl group or an ethyl group.) A color-forming recording material characterized by using a fluoran compound represented by the following formula. (2) The color-forming recording material according to claim (1), which is a pressure-sensitive recording material. (3) The color-forming recording material according to claim (1), which is a heat-sensitive recording material.