JPH0399882A - Heat-sensitive recording material - Google Patents

Abstract

PURPOSE:To obtain a thermosensitive paper improved on color sensitivity without staining the surface after a picture-keeping quality test by containing a specific into compound in a recording layer. CONSTITUTION:This thermal recording material is obtained when a recording layer fundamentally having colorless or a little light-colored electron donative colorless dye, acid material coloring the electron donative colorless dye on heating and binder is provided on a support. Also, a nitro compound shown by a general formula (I) is contained in the recording layer. As the electron donative colorless dye to be used, there are known trialimethane compounds, diphenylmethane compounds, fluorene compounds, etc. The weight ratios of respective compounds and binder to a coloring agent in the recording layer are the gross weight of the nitro compound shown by the general formula (I) of 0.5-10 times and that of the binder of 0.3-3 times. This thermosensitive paper is extremely excellent in heat-resisting keeping quality and especially in coloring sensitivity out of heat sensitive characteristics without causing a whitening phenomenon and being also excellent in the fogging of the heat- resisting surface.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material that is highly sensitive, has excellent light resistance and moisture resistance, and has improved heat-sensitive characteristics. In particular, it relates to thermal recording paper with improved color development sensitivity.

(Prior art) The recording layer of thermal recording paper should have the following properties: self-coloring resistance, pressure coloring resistance, light resistance, heat decoloring resistance, moisture decoloring resistance,
and has excellent heat-sensitive properties such as water resistance, but currently no material has been obtained that completely satisfies these requirements.

On the other hand, as society demands higher speed recording transmission, there is a need not only for the speed of the recording apparatus itself to increase, but also for heat-sensitive recording materials with high sensitivity, that is, low energy and high density color development.

Conventionally, in order to improve color development sensitivity, Japanese Patent Application Laid-Open No. 59-305
57, JP-A-60-82382, JP-A-63-1267
There are proposals to add a low melting point compound to the heat-sensitive recording layer, such as in JP-A-84 and JP-A-64-40373.

(Problems to be Solved by the Invention) The present inventors used a known electron-donating colorless dye as a coloring agent to produce a thermosensitive recording medium according to a conventionally known method and the method described in each of the above-mentioned patent publications. When paper was manufactured and tested for the performance it should have as a thermal recording paper,
Compounds with excellent color development sensitivity and excellent image stability showed thicker background fog and thicker background fog after image storage tests (and were insufficient for the purpose of increasing the sensitivity of heat-sensitive recording materials). .

The present invention provides a heat-sensitive recording paper with improved color development sensitivity without staining the background after an image storage test.

(Means for Solving the Problems) The present inventors have completed the present invention as a result of intensive research to improve the above-mentioned drawbacks of heat-sensitive recording materials using known electron-donating colorless dyes. be.

That is, the present invention provides a recording layer on a support that basically includes a colorless or slightly pale colorless electron-donating dye, an acidic substance that causes the colorless electron-donating dye to develop color when heated, and a binder. In the heat-sensitive recording material, the recording layer contains the following general formula (I) (wherein R is an alkyl group having 1 to 20 carbon atoms or a carbon number 1 to 20).
5 alkyl group, 1 to 5 alkoxy group, or halogen atom;
It is a heat-sensitive recording material with a long life.

General formula (I) Specific examples of nitro compounds shown in However, the present invention is not limited thereto.

Known electron-donating colorless dyes used in the present invention include triallylmethane compounds, diphenylmethane compounds, xanthine compounds, thiazine compounds, oxazine compounds, spiropyran compounds, and fluorene compounds.

To give some examples of these, triarylmethane compounds include 3,3-bis(p
-dimethylaminophenyl)-6-dimethylaminophthalide (CVL), 3.3-bis(P-dimethylaminophthalide, 3-(p-dimethylaminophenyl)-3-
(I,3-dimethylindol-3-yl)phthalide,
3-(p-dimethylaminophenyl)-3-(2-methylindol-3-yl)phthalide, and xanthine compounds include rhodamine B-anilinolactam,
Rhodamine (p-nitroanilino)lactam, Rhodamine B (p-chloroanilino)lactam, 2-dibenzylamino-6-diethylaminofluorane, 2-anilino-6-diethylaminofluorane, 2-anilino-3-
Methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-(N-cyclohexyl-N-methyl)aminofluorane, 2-0-chloroanilino-6=diethylaminofluorane, 2-o-chloroanilino -6
-sibutylaminofluorane, 2-p-chloroanilino-6-diethylaminofluorane, 2-octylamino-6-diethylaminofluorane, 2-p-acetylanilino-6-diethylaminofluorane, 2-ethoxyethylamino- 3-chloro-6-diethylaminofluorane, 2-anilino-3-chloro-6-diethylaminofluorane, 2-diphenylamino-6-diethylaminofluorane, 2-anilino-3-methyl 6-(N-ethyl-N -isoamyl)aminofluorane, 2-anilino-3-methyl-6-cyphenylaminofluorane, 2
-anilino-6=(N-ethyl-N-)lyl)aminofluorane, 2-anilino-3-methyl-6-(N-ethylN-1-lyl)aminofluorane, 2-anilino3-
Methyl-6-(N-methyl-N(n)-propyl)aminofluorane, 2-anilino-3-methoxy-6-sibutylaminofluorane, 2-anilino-3-methyl-
6-di(n)butylaminofluorane, 2-anilino-
3-Methyl-6(N-ethyl-N-tetrahydrofurfuryl)aminofluorane, 2-anilino-3-methyl-
6-(N-(n)butyl-N-tetrahydrofurfuryl)aminofluorane, 5-hydroxy-10-(N-ethyl-N-r'-)lylamino)fluorane, 2-chloro-3-methyl-6 -P-(Pphenylaminophenyl)aminoanilinofluorane, 2-P-phenylureidoanilino-6-N-cyclohexyl-N-methylaminofluorane, fluorene-based compounds include 3"
6゜Bisdiethylamino-5-diethylaminospiro (
Isobenzofuran-1,9°-fluorene)3'-one, 3'-6'-bisdiethylamino5-dibutylaminospiro(isobenzofuran 1,9'-fluorene)-
3°-one, etc., and pentadiene compounds include 1-(α-methoxy-(4-N,N dimethylamino)
benzyl)-3-(4-N,N-dimethylaminobenzylidene)-5-methyl-cyclohexene, etc., and thiazine compounds include benzoylleucomethylene blue, p-nitrobenzylleucomethylene blue, etc.
Examples of oxazine compounds include 3,7-bis(diethylamino)-10-benzoyl-phenoxazine, 3,7
-bis(diethylamino)-10-acetylphenoxazine, etc., and spiro compounds include 3-methylspirodinaphthopyran, 3-benzylspiro-dinaphthopyran, 3-propyl-spiro-dibenzopyran, and the like.

These may be used alone or in combination.

The present invention is not limited to these electron-donating colorless dyes. Further, as the electron-accepting compound (color developer) used in the present invention, phenolic compounds, organic acids or metal salts thereof, hydroxybenzoic acid esters, etc. are preferable, and specific examples include the following. .

Salicylic acid, 3-isopropylsalicylic acid, 3-cyclohexylsalicylic acid, 3,5-di-tertbutylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, 4
, 4′-isopropylidene diphenol, 4,4′-isopropylidene bis(2-chlorophenol L4,4°
-isopropylidene bis(2,6-dibromophenol), 4.4°-isopropylidene bis(2,6-dichlorophenol), 4.4”-isopropylidene bis(2
-methylphenol), 4.4''-isopropylidene bis(2,6-dimethylphenol), 4.4'-isopropylidene bis(2ter t-butylphenol)
, 4.4'-5ec-butylidene diphenol, 4,
4°-cyclohexylidene bisphenol, 4,4゛
-Cyclohexylidenebis(2-methylphenol)
, 4-tertbutylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, α-naphthol, β-naphthol, 3.5-xylenol, thymol,
Methyl-bis(4-hydroxyphenyl)acetate,
(n) Butyl-bis(4-hydroxyphenyl)acetate, 4,4゛-thiodiphenol, bis(4-hydroxy-3-methylphenyl)sulfide, 4,4-diphenolsulfone, 4-isopropoxy-4 °-Hydroxydiphenylsulfone, 1,7-di(4-hydroxyphenylthio)-3,5-dioquimosahebutane, phloroglycincarboxylic acid, 4-tert-octylcatechol, 2,2'-methylenebis(4-chlorophenol) )
, 2.2″-methylenebis(4methyl-6-tert-
butylphenol), 2゜2''-dihydroxydiphenyl, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, butyl p-hydroxybenzoate, p-
Benzyl hydroxybenzoate, p-chlorobenzyl p-hydroxybenzoate, 0-chlorobenzyl p-hydroxybenzoate, p-methylbenzyl p-hydroxybenzoate, n-octyl p-hydroxybenzoate, benzoic acid, zinc salicylate , 1 hydroxy-2-naphthoic acid, 2
-hydroxy-6-naphthoic acid, 2-hydroxy-6-
naphthoe MAL 4-hydroxydiphenylsulfone,
4-Hydroxy-4°-chlorodiphenyl sulfone, bis(4-hydroxyphenyl) sulfide, 2-hydroxy-pt-ruylic acid, 3. Zinc 5-tert-butylsalicylate, 3,5-tin di-tert-butylsalicylate, tartaric acid, oxalic acid, maleic acid, citric acid, succinic acid, stearic acid, 4-hydroxyphthalic acid, boric acid, thiourea derivative, 4 Examples include hydroxythiopheneol derivatives.

A water-soluble or water-insoluble binder is used as the binder for binding the mixture of color former and color developer onto the support sheet. Typical examples include polyvinyl alcohol, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, gum arabic, starch, gelatin,
Casein, polyvinylpyrrolidone, styrene-maleic anhydride copolymer, polyacrylic acid amide, polyacrylate, terpene resin, petroleum resin, etc., but the binder that can be particularly preferably used in the present invention is a water-soluble binder. A typical adhesive is polyvinyl alcohol.

Next, a specific example of manufacturing a heat-sensitive recording paper using the heat-sensitive recording material of the present invention will be shown.

When manufacturing heat-sensitive recording paper, the weight ratio of each of the above-mentioned components and binder in the recording layer to the color former is
The total amount of nitro compounds represented by general formula (I) is 0.5 to
10 times, preferably 2 to 4 times, and the binder is 0.3 to 4 times
It is 3 times, preferably 0.5 to 2.0 times.

The color former and the color developer are preferably used separately in a dispersing machine such as a ball mill, a guino mill, a sand mill, or a paint conditioner, and the compound represented by general formula (I) is used alone or together with the color former, or in the color developer. It may also be dispersed in water or an organic medium containing a binder, preferably water in which the binder is dissolved, and pulverized to a particle size of 1 to 6 μm, preferably 2 to 4 μm. Create a suspension with a particle size. If necessary, an antifoaming agent, dispersant, or brightener may be added for dispersion and pulverization.

Next, each of the above components is separately dispersed, and a suspension of the pulverized components is mixed so that the weight ratio of each component in the recording layer is as described above to prepare a paint for forming a heat-sensitive recording layer. . Apply this paint to the surface of the paper with wire bar #6~
Using #20, the weight of the solid after drying is 3 to 10 g/r.
A thermosensitive recording paper is produced by applying the coating to a temperature of Tf and drying it in a blow dryer at room temperature to 70°C. If necessary, inorganic or organic fillers may be added to the paint to improve the fusing resistance, writability, etc. of the thermal head.

(Effect of the invention) The thermal recording paper thus obtained has the following thermal characteristics:
It has extremely excellent heat-resistant storage stability, especially color development sensitivity, and also has no whitening phenomenon that impairs its commercial value as a thermal recording paper, and has excellent heat-resistant background fog, which effectively overcomes the shortcomings of conventional thermal recording papers. Met.

(Examples) The present invention will be specifically explained below using Examples, but the present invention is not limited by these Examples.

Example I Solution A (dye dispersion) Solution B (developer dispersion) Solution C (filler dispersion) (30% calcium carbonate aqueous dispersion, ND solution (binder solution) (10% polyvinyl alcohol aqueous solution) 1 Each of the above compositions A, B, and C was mixed with a Guino Mill KDL disperser to a particle size of 1.5.
~3. Grind down to microns.

Next, each method is mixed in the following proportions to prepare a heat-sensitive paint.

This mixed paint was applied to the surface of high-quality paper using a Nα18 wire bar coater so that the solid content weight after drying was 7 g/rd, and the mixture was placed in a blow dryer and dried to obtain a heat-sensitive recording material.

Example 2 The compound according to the present invention, 4-chloro-2-nitroanisole, in liquid B was replaced with 4-chloro-2-nitrophenyl-(n)
-A liquid separation solution E was obtained in exactly the same manner as the preparation of liquid B, except that butyl ether was used.

Next, each method is mixed in the following proportions to prepare a heat-sensitive paint.

A heat-sensitive recording material was obtained in exactly the same manner as in Example 1 using the above paint.

Example 3 The process was carried out in exactly the same manner as the preparation of Solution B, except that 4-chloro-2nitroanisole related to the compound of the present invention in Solution B was changed to 4-chloro-2-nitrophenylbenzyl ether, and the dispersion of Solution F was prepared. Obtained. Next, each method is mixed in the following proportions to prepare a heat-sensitive paint.

Thereafter, using the above coating material, the same procedure as in Example 1 was carried out to obtain a heat-sensitive recording material.

Example 4 The process was carried out in exactly the same manner as the preparation of Solution B, except that 4-chloro-2-nitroanisole, which is the first descendant of the compound of the present invention, in Solution B was changed to 3-chloro-6-nitrophenyl ether, and dispersion of Solution G was carried out. I got the liquid.

Next, each method is mixed in the following proportions to prepare a heat-sensitive paint.

Thereafter, using the above coating material, the same procedure as in Example 1 was carried out to obtain a heat-sensitive recording material.

Example 5 A dispersion of liquid H was obtained in exactly the same manner as in Example 1 except that the composition of liquid B was changed to the following.

Next, each method is mixed in the following proportions to prepare a heat-sensitive paint.

Thereafter, using the above coating material, the same procedure as in Example 1 was carried out to obtain a heat-sensitive recording material.

Example 6 The preparation of Solution H was carried out in exactly the same manner as in Example 5 except that 4-chloro-2-nitroanisole related to the compound of the present invention was changed to 4-chloro-2-nitrophenylbenzyl ether.
A liquid dispersion was obtained.

Next, each method is mixed in the following proportions to prepare a heat-sensitive paint.

Using the above paint, the same procedure as in Example 1 was carried out to obtain a heat-sensitive recording material.

Example 7 The process was carried out in exactly the same manner as the preparation of solution H, except that 4-chloro-2-nitroanisole related to the compound of the present invention in Example 5 was changed to 3-chloro-6-nitrophenyl phenyl ether, and J
A liquid dispersion was obtained. Next, each method is mixed in the following proportions to prepare a heat-sensitive paint.

Using the above paint, the same procedure as in Example 1 was carried out to obtain a heat-sensitive recording material.

Control Example 1 A liquid K dispersion was obtained in exactly the same manner as in the preparation of liquid B, except that 4-chloro-2=nitroanisole related to the compound of the present invention in liquid B was changed to rosebenzylbiphenyl.

Next, each method is mixed in the following proportions to prepare a heat-sensitive paint.

Using the above paint, the same procedure as in Example 1 was carried out to obtain a heat-sensitive recording material.

Control example 2 H? A liquid L dispersion was obtained in exactly the same manner as in the preparation of liquid H except that the compound 4-chloro-2nitroanisole according to the present invention in l was changed to parahensyl biphenyl.

Next, each method is mixed in the following proportions to prepare a heat-sensitive paint.

Using the above paint, the same procedure as in Example 1 was carried out to obtain an infection recording material.

The heat-sensitive recording materials obtained in Examples 1 to 7 and Comparative Example 1.2 were each cut into prescribed sheets of 20 cm width, and calendered using a mini calender manufactured by Yuri Roll so that the smoothness was 300 seconds. A performance test was conducted.

The results are shown in the Examples and Control Examples column in Table 1.

Note: In the color density-color energy curve where the vertical axis is the color density and the horizontal axis is the color energy, an energy load of 1.5 kg of 7.5 mj to 75 mj was measured using a dynamic color tester manufactured by Matsushita Electronics. / afl coloring conditions,
Colored thermosensitive recording paper. The coloring area was measured with a Macbeth reflection densitometer model RD-918, and the coloring energy showing a reflection density of 1.0 was Jl. The energy at this time (m
j millijoules) was named the color development sensitivity.

Note ■: The uncolored area under the conditions described in ■ above is removed from the background.

And so.

Note ■ Indicates heat-resistant storage stability after heat color development, Jl, which developed color under the conditions of Note ■. The color density Dt of the part was measured after 124 hours at 60°C, and the color retention rate (%) - (Dz /1.
0)X100 was determined, and this was defined as heat resistance.

After 124 hours at 60° C., the color density of the uncolored portion was measured, and this was named heat-resistant background D3.

Note ■ Jl, which represents the moisture decoloring resistance after color development by heating, was developed under the conditions of Note ■. Color density (D'z) of the colored part after 24 hours at 50°C2 90% relative humidity
Measure the residual color rate (%) - (D'z/ 1-0)
x 100 was determined, and this was defined as the moisture decoloring resistance.

As is clear from the table, the heat-sensitive recording material of the present invention has significantly improved sensitivity and heat-resistant storage stability compared to heat-sensitive recording materials containing conventionally known sensitizers such as parabenzylbiphenyl.

Hodogaya Chemical Industry Co., Ltd.

Claims (1)

[Claims] A recording layer is provided on a support, which basically includes a colorless or slightly pale colorless electron-donating dye, an acidic substance that causes the colorless electron-donating dye to develop color when heated, and a binder. In the thermal recording paper made of , there are tables, etc. ▼, ▲ there are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ there are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ there are mathematical formulas, chemical formulas, tables, etc. ▼, R_1 is a hydrogen atom, the number of carbon atoms is 1 -5 alkyl group, 1-5 alkoxy group or halogen atom, X is a halogen atom, n is 1-5
Represents an integer of 5. ) A heat-sensitive recording material characterized by containing a nitro compound represented by: