JP2854026B2 - Fluoran compounds and recording materials containing said compounds - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fluoran compound useful as a color-forming compound used in recording materials such as pressure-sensitive recording materials and heat-sensitive recording materials, and a recording material containing the compound. .

[Conventional technology]

Conventionally, a colorless or light-colored electron-donating compound (color-forming compound) and an organic or inorganic electron-accepting substance (color developer)
As a method for recording information transmitted by utilizing a color reaction with the external energy such as pressure, heat or electricity, there are pressure-sensitive recording, heat-sensitive recording and energized heat-sensitive recording.

In these recording methods, a fluoran compound is widely used as a coloring compound.

Conventionally, as the fluoran compound, for example, compounds of the formulas (IV), (V), (VI), (VII) and (VII) are known.

However, the compound of the formula (IV) has a drawback that when used in a pressure-sensitive recording material, it has a very low solubility in capsule oil. In addition, when used as a heat-sensitive recording material, a compound such as bisphenol A is used. The mixture itself has a drawback that it develops a gray or black-grey color, and when it is applied to paper, only a gray-to-black gray colored (ground stain) paper is obtained.

The compounds of formulas (V) and (VI) have a relatively good dissolution concentration in capsule oil, but when used in a heat-sensitive recording material, only soiled paper can be obtained as in the case of the compound of formula (IV). Or discoloration to gray during storage. As a pressure-sensitive recording material, a color-forming compound having high solubility in capsule oil and having high whiteness and excellent storage stability of paper is strongly desired as a heat-sensitive recording material.

Furthermore, the compounds of formulas (VII) and (VIII) also have poor solubility in capsule oil.

[Problems to be solved by the invention]

An object of the present invention is to provide a coloring material for a recording material,
An object of the present invention is to provide a novel fluoran compound that can meet the above-mentioned demands, and to provide a method for producing the compound and a recording material containing the compound.

[Means for solving the problem]

The present inventors have searched for various compounds in order to solve the above-mentioned problems, and have reached the present invention.

That is, the present invention provides a compound of the formula (I) And a recording material characterized by containing this compound.

This fluoran compound has the formula (II) A benzoic acid derivative represented by the general formula (III) (Wherein, R represents a lower alkyl group).

The fluoran compound of the present invention is represented by the above formula (I).

The benzoic acid derivative of formula (II) used to make this compound is typically 3-N-cyclohexyl-N
-Allylaminophenol and phthalic anhydride without solvent,
Alternatively, it can be produced by reacting in a solvent such as benzene, toluene, xylene or tetrachloroethylene. In this reaction, a Lewis acid such as zinc chloride may be added.

In the diphenylamine derivative represented by the general formula (III), R represents a lower alkyl group, and specific examples of the lower alkyl group include a methyl group and an ethyl group as preferred examples.

The fluoran compound of the formula (I) is a diphenylamine derivative of the general formula (III) of the benzoic acid derivative of the formula (II),
For example, concentrated sulfuric acid, concentrated sulfuric acid to which fuming sulfuric acid is added, polyphosphoric acid, phosphorus pentoxide, anhydrous aluminum chloride and the like, more preferably in concentrated sulfuric acid after the reaction in the presence of a dehydrating condensing agent, and then can be suitably produced by making it alkaline. . The reaction temperature of the dehydration-condensation is preferably from 0 to 100 ° C, and particularly preferably from 0 to 50 ° C when the reaction is carried out in concentrated sulfuric acid.

Although the reaction time greatly depends on the reaction temperature, it is usually preferable to carry out the reaction for several hours to 100 hours. After the dehydration condensation, usually, an alkali treatment is performed. In the case of performing the alkali treatment, the pH is adjusted to 9 to 12 with potassium hydroxide, sodium hydroxide aqueous solution or the like, and the treatment is performed in a range of 0 to 100 ° C. Is preferred. At this time, the alkali treatment may be performed in the presence of a solvent other than water, such as benzene or toluene.

When the fluoran compound represented by the formula (I) of the present invention is used as a color-forming compound in various recording materials, this compound can be used alone, and further, for example, to adjust the color of the color, Other color-forming compounds, for example, triphenylmethanelactones, fluorans, and spiropyrans may be used as a mixture if desired.

When the fluoran compound represented by the formula (I) is used, for example, as a pressure-sensitive recording material, it is used in a solvent commonly used in this field, for example, an alkylbenzene-based compound (such as n-dodecylbenzene) or an alkylbiphenyl-based compound. Triethylbiphenyl, diisopropyldiphenyl, etc.), hydrogenated terphenyls, alkylnaphthalenes (diisopropylnaphthalenes, etc.), diarylethanes (phenylxylylethane, styrenated ethylbenzene, etc.), or various solvents of chlorinated paraffins alone or mixed It is dissolved in a solvent, and the solution is encapsulated in a microcapsule having a partition wall of gelatin, melamine-aldehyde, or urea-aldehyde resin, polyurethane, polyurea, polyamide, or the like by a method such as coacervation method or interfacial polymerization method. Apply the aqueous dispersion of the obtained capsule It can be applied to a suitable support (for example, paper, plastic sheet, resin-coated paper, etc.) together with a binder (for example, starch paste, latex, etc.) and used as a pressure-sensitive recording sheet. it can.

Of course, the above-mentioned capsule dispersion liquid was applied to one surface of the support, and a developer coating solution mainly comprising a developer was applied to the opposite surface, a so-called intermediate sheet, and further, the same surface of the support By applying a coating solution in which a capsule and a developer are mixed, or by applying a developer coating solution after applying a capsule dispersion, the capsule and the developer coexist on the same surface, so-called It can also be used for single copy sheets.

In this case, as the color developer, a very large number of copolymers of saliteric acid, phenols and aldehydes (for example, formaldehyde), and substituted salicylic acids (alkyl-substituted, aryl-substituted or aralkyl-substituted) are known. 5-di-α-methylbenzyl salicylic acid), co-condensation resin of substituted salicylic acid and styrene, alkylphenols (eg, octylphenol), phenol-aldehyde resins (eg, novolak resin of p-phenylphenol) or metals thereof Salts (eg, zinc, magnesium, aluminum, calcium,
Metal salts such as tin and nickel), and activated clay.

When the fluoran compound represented by the formula (I) of the present invention is used for a heat-sensitive recording material, the compound of the formula (I) and a color developer (for example, bisphenol A or a halide or alkylated product thereof, dihydroxydiphenylsulfone) Or a halide or alkylated product thereof, hydroxybenzoic acid esters, phenols such as hydroquinone monoethers, salicylic acid derivatives, salicylic acid amide derivatives, urea derivatives, organic developers such as thiourea derivatives, acid clay, apadalgaite, Activated clay,
A binder (for example, polyvinyl alcohol or a modified product thereof, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, gum arabic, styrene-maleic anhydride) is added to a fine aqueous acid solution of an inorganic developer such as aluminum chloride or zinc bromide. Polymer salt, isobutylene-acrylic acid-maleic anhydride copolymer, etc.),
Pigments (talc, kaolin, calcium carbonate, etc.)
If necessary, sensitizers (such as higher fatty acid amides, esters of aromatic carboxylic acids or sulfonic acids, aromatic or aromatic-substituted aliphatic ethers, or aromatic or aromatic-substituted aliphatic hydrocarbons) A known dispersion for a heat-sensitive recording material) and other additives (for example, an ultraviolet absorber, an antifoaming agent, etc.) are added to form a fine dispersion, and a suitable support (for example, paper, a plastic sheet, resin-coated) is prepared. Coated paper) and used as a heat-sensitive recording material.
Of course, it can be used without problem in a system using a solvent instead of an aqueous dispersion system.

It can be used for applications using other color-forming compounds (for example, temperature indicating materials).

[Action]

When the fluoran compound represented by the formula (I) of the present invention is used in a pressure-sensitive recording material, it has high solubility in capsule oil, which is an important property strongly desired for a color-forming compound used in the pressure-sensitive recording material, and The weather resistance of a color image after color development is excellent. That is, the solubility of the fluoran compound of the formula (I) of the present invention in a commercially available capsule oil,
The results as compared with the fluoran compounds of formulas (IV), (V), (VII) and (VIII) are as shown in Table 1.

The solubility of each fluoran compound of the formulas (I), (IV), (V), (VII) and (VIII) was once dissolved in each oil by 5% by weight, and then dissolved at 5 ° C. After storage for one week, the presence or absence of crystal precipitation was indicated.

As is evident from Table 1, the fluoran compounds of the formula (I) according to the invention are compared with the fluoran compounds of the formulas (IV), (V), (VII) and (VIII) High solubility in each oil. This means that when making a pressure-sensitive recording material, there is no crystal precipitation during storage in capsule oil,
Furthermore, it means that there is no danger of crystal precipitation in the microcapsules after microencapsulation, and the formula (I) of the present invention
This is a major feature of the fluoran compound represented by In particular, even for a mixed system of SAS-296 and IP oil, exhibiting extremely good solubility means that even cheaper capsule oil can be used, which is economical and industrially advantageous. .

Further, when the fluoran compound of the formula (I) of the present invention is used for a heat-sensitive recording material, a heat-sensitive paper free of background stain and having high whiteness is obtained, and the storage stability of the paper is very excellent.

That is, a thermal paper using bisphenol A as a color developer and a fluoran compound of the formula (I) of the present invention as a color-forming compound and fluoran compounds of the formulas (IV), (V) and (VI) are used. Table 2 shows the results of comparison of the moisture and heat resistance of the heat-sensitive papers prepared as described above.

In the moist heat test, a thermal paper prepared using each compound was stored at 40 ° C. and a relative humidity of 60% for 24 hours, and the stain on the paper was visually observed.

The fluoran compound of the formula (I) of the present invention is different from the fluoran compounds of the formulas (IV) and (V) in that the substituent on the amino group at the 3-position and the 2 on the anilino group at the 7-position in the fluoran structure And the only difference from the fluoran compound of formula (VI) is that only the substituent on the amino group is different. However, as described above, equations (IV) and (V)
The fluoran compound of formula (I) of the present invention has very excellent characteristics in terms of solubility in capsule oils, coloring characteristics by heat, and storage stability as a thermal paper as compared with the fluoran compound of formula (I). Is surprising.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Example 1 [Production of compound of formula (I)] 20 g of 2- (4'-N-cyclohexyl-N-allylamino-2'-hydroxybenzoyl) benzoic acid was dissolved in 100 ml of concentrated sulfuric acid at 10 ° C. 12.7 g of methoxy-2,2 ', 4'-trimethyldiphenylamine was added at the same temperature, and 10 to 2
Stirred at 5 ° C. for 48 hours. The reaction mixture was discharged into 600 ml of ice water, the precipitated solid was collected, washed with water, and then washed with 10% NaOH
It was added to water (500 ml) and stirred at 60-70 ° C for 2 hours. The solid was filtered, washed with water, and then washed with 100 ml of isopropanol. Further, the product was recrystallized twice with n-butanol to give the desired 3-N-cyclohexyl-N-allylamino-6-methyl-7- (2 ', 4'-dimethylanilino) fluoran 1
7.1 g (57% yield) were obtained as almost colorless crystals. Melting point: 197.2-198.8 ° C. A toluene solution of this compound was anhydrous and transparent, and quickly developed black color on silica gel.

Example 2 3-N-cyclohexyl-N-allylamino-6-methyl-7- (2 ', 4'-dimethylanilino) fluoran
10 g, 5 g of 10% polyvinyl alcohol aqueous solution and water 37.
5 g of the mixture was pulverized with a sand mill to a particle size of 3 μm. On the other hand, bisphenol A was dispersed in the same manner to obtain a 38% color developer dispersion.
-Cyclohexyl-N-allylamino-6-methyl-7
50 g of an aqueous dispersion of-(2 ', 4'-dimethylanilino) fluoran, 18.3 g of a 60% aqueous calcium carbonate aqueous dispersion, 88 g of a 10% aqueous polyvinyl alcohol solution and 51.9 g of water were mixed.

This mixture was applied to white base paper using a wire rod No. 10 and then air-dried at room temperature to obtain a very white thermosensitive recording paper free of background stain. This heat-sensitive recording paper developed black color very quickly by heating.

When this thermosensitive recording paper was stored at 40 ° C. and 60% relative humidity for 24 hours, no stain was found on the paper (No. 2).
table).

Comparative Example In Example 2, 3-N, N-dimethyl-6-methyl-6- (2 ′, 4′-dimethylanilino) fluoran was used instead of 3-N-cyclohexyl-N-allyl-6-methyl-7- (2 ′, 4′-dimethylanilino) fluoran.
Methyl-7-anilinofluoran [compound of formula (IV)], 3-N-cyclohexyl-N-methylamino-6
-Methyl-7-anilinofluoran [compound of formula (V)] or 3-N, N-diethylamino-6-methyl-7
-(2 ', 4'-dimethylanilino) fluoran [formula (V
Each of the compounds (I) was used to prepare a thermosensitive recording paper according to the method described in Example 2. The coated surface of the paper using the compound of the formula (IV) or the compound of the formula (VI) was slightly gray and background stains were observed.

When the heat-sensitive recording paper using each compound was stored at 40 ° C. and 60% relative humidity for 24 hours, it was recognized whether or not the paper had a gray background (Table 2).

Example 3 Upper (CB) paper and lower (CF) paper were prepared as follows.

That is, 10% of the ethylene-maleic anhydride copolymer
100 g of an aqueous solution of water and 240 g of water, and adjusted to pH 4.0 with a 10% aqueous sodium hydroxide solution to give 3-N-cyclohexyl-N
-Allylamino-6-methyl-7- (2 ', 4'-dimethylanilino) fluoran was mixed with 200 g of phenylxylylethane (SAS-296, manufactured by Nippon Petrochemical) in which 5% by weight was dissolved, and emulsified with a homomixer. And a 50% solids aqueous methylol melamine solution (Euramine T-Mitsui Toatsu Chemicals, Inc.)
30) 60 g was added, and the mixture was kept at 55 ° C. for 3 hours while stirring to obtain a microcapsule dispersion having an average particle size of 5.0 μm.

In 100 g of this microcapsule dispersion, wheat flour starch granules 4.
Add 0 g, 20 g of 20% oxidized starch paste and 116 g of water, disperse,
It was applied to a paper having a basis weight of 40 g / m ^{2 so} that the coating amount was 5 g / m ² in terms of solid content, to obtain CB paper.

On the other hand, CF paper uses a zinc salt of a co-condensation resin of substituted salicylic acid and styrene as a color developing agent, is pulverized in a sand grinding mill in water in the presence of a small amount of a polymer anionic surfactant, and has a solid content of 40%. A weight% aqueous dispersion was obtained. Using this aqueous dispersion, an aqueous paint of the following composition (solid content 30%)
Was prepared and applied to a high-quality paper having a basis weight of 40 g / m ^{2 so} as to have a dry coating amount of 5.5 g / m ² , thereby producing CF paper.

Composition of water-based paint Solid weight (g) Light calcium carbonate 100 Developer 20 Adhesive Oxidized starch 8 Synthetic latex 8 Overlay the microcapsule application surface of CB paper and the developer application surface of CF paper so that they face each other When combined, written, and pressed, a green-black color image was obtained on the developer-coated surface. The light resistance, moisture resistance and No _X resistance of this color image were practically satisfactory.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-59-157153 (JP, A) JP-A-3-190879 (JP, A) JP-A-3-55286 (JP, A) 55288 (JP, A) JP-A-3-63172 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C09B 11/28 B41M 5 / 124-5 / 165 CA (STN)

Claims (2)

(57) [Claims] 1. A fluoran compound represented by the general formula (I). 2. A recording material comprising the fluoran compound represented by the general formula (I) according to claim (1).