JPH0485078A - Thermal recording material - Google Patents

Abstract

PURPOSE:To enhance color forming sensitivity and heat resistance without contaminating a background after the preservation of an image by adding a specific dibenzofuran, compound to the recording layer of thermal recording paper. CONSTITUTION:Thermal recording paper is formed by providing a recording layer containing a colorless or light-colored electron donating leuco dye, an acidic substance allowing said dye to form a color at the time of heating and a binder on a support. A benzofuran compound represented by formula (I) (wherein R is an alkyl group or an aralkyl group which may be substituted) is added to the recording layer. By controlling the m.p. of this benzofuran compound, a thermal recording material having arbitrary sensitivity can be provided but a compound having an m.p. of 40-150 deg.C, especially, 60-120 deg.C is pref. from the aspect of storage stability and sensitivity.

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. It's about marriage.

(Conventional technology) The recording layer of thermosensitive recording paper should have excellent heat-sensitive properties such as self-coloring resistance, pressure coloring resistance, light resistance, heat decolorization resistance, color erasability, and water resistance. However, there is currently no one that fully satisfies these requirements.On the other hand, with the increasing speed of recording transmission, which is essential to society, the speed of recording devices themselves has increased, but this is becoming more and more important. There is a need for a heat-sensitive recording material with high sensitivity, that is, a heat-sensitive recording material that can develop colors with high density and low energy.

Conventionally, in order to improve color development sensitivity, Japanese Patent Application Laid-Open No. 57-116
690, JP-A-57-64592, JP-A-58-112
788, JP 59-30557, JP 60-565
88, JP 60-82382, JP 61-2721
89, JP-A No. 63-126784, and JP-A No. 64-
There are proposals to add compounds such as 40373 into the thermosensitive recording layer.

(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 the materials were manufactured and tested for the performance they should have as a thermal recording paper, it was found that compounds with excellent color development sensitivity and excellent image stability had large background fog and image storage properties of 11&, and were not suitable for thermal recording materials. This was insufficient for the purpose of increasing sensitivity.

(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. The object of the present invention is to provide a thermal recording paper that has improved color development sensitivity and heat resistance without staining the background after an image storage test.

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. A thermosensitive recording material characterized in that the recording layer contains a dibenzofuran compound represented by the general formula (wherein R is an alkyl group or an optionally substituted aralkyl group). .

The dibenzofuran compound used in the present invention can provide a heat-sensitive recording material with any sensitivity by adjusting the melting point.
A temperature of 0°C is preferable, and a temperature of 60°C to 120°C is particularly preferable. Specific examples of the dibenzofuran compound of the present invention are shown on the next page, but the present invention is not limited thereto.

(h) As the electron-donating colorless dye used in the present invention, triallylmethane compounds, diphenylmethane compounds, xanthine compounds, thiazine compounds, oxazine compounds, spiropyran compounds, fluorene compounds, etc. are known. Some examples include 3,3-bis(P-dimethyl 7) as a triallylmethane compound.
minophenyl)-6-dimethylaminophthalide (CVL
I, 3.3-hyphenyl, (P-cyfyl7mi/phenylphthalide), 3-(P-dimethylaminophenyl)-3-
(1,3-dimethylindol-3-yl)phthalide,
3-(P-dimethylaminophenyl)-3-(2-methylindol-3-yl)phthalide, 3.3-bis((
2-(4-methoxyphenyl)-2-(4-dimethylaminophenyl)ethynyl))-4,5,6,7tetrachlorophthalide 3.3-bis((1,1-bis(4-viroli) dironophenyl)ethylene-2-yl))-4,5
, 6,7 tetrachlorophthalide, etc., and xanthine compounds include rhodamine B-anilinolactam, rhodamine B (P-nitroanilino)lactam, rhodamine B (P-chloroanilino)lactam, 2-dibenzylamino-6- Diethylaminofluorane, 2-anilino-
6-diethylaminofluorane, 2-anilino-3-methyl-6-diethylaminofluorane, 2-7nilino-3-methyl-6-(N-cyclohexyl-N-methyl)
Aminofluorane, 2-o-chloroanilino-6-diethylaminofluorane, 2-0-chloroanilino-6-
Sibutylaminofluorane, 2-p-chloroanilino-
6-diethylaminofluorane, 2-octylamino-
6-diethylaminofluoran, 2-p-acetylanilino-6-diethylaminofluoran, 2-ethoxyethylamino-3-chloro-6-diethylaminofluoran, 2-7nilino-3-chloro-6-diethylaminofluoran, 2-diphenylamino-6-diethylaminofluorane, 2-anilino-6-(N-ethyl-N-tolyl)aminofluorane, 2-anilino-3-methyl-
6-(N-ethyl-N-4lyl)aminofluorane, 2
-anilino-3-methyl-6-(N-methyl-N-n-
propyl) aminofluorane, 2-7nilino-3-methoxy-6-sibutylaminofluorane, 2-7nilino-3-methyl-6-N,N-diethylaminofluorane,
2-anilino-3-methyl-6-(N-ethyl-N-tetrahydrofurfuryl)aminofluorane, 2-anilino-3-methyl-6-(N-nbutyl-N-tetrahydrofurfuryl)aminofluorane , 2-anilino-3-
Methyl-6-(N-ethyl-N-isoamyl)aminofluorane, 2-chloro-3-methyl-6-p-(p-phenylaminophenyl)aminoanilinofluorane, 2
-p-phenylureidoanilino-6-N-cyclohexyl-N-methylaminofluorane, etc., and examples of fluorene compounds include 3',6°bisdiethylamino-5-diethylaminospiro (isobenzofuran-1 ，
9-fluorene〉-3°-one, 3°, 6° bisdiethylamino-5-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. Thiazine compounds include penzoyl leucomethylene blue, p-nitropenzyl leucomethylene blue, etc., and oxazine compounds include 3.7-bis( diethylamino)-10-pensylphenoxacin, 3,7-bis(diethylamino)-10-acetylphenoxazine, etc., and spiro-based compounds include 3-methylspirodinaphthopyran, 3-benzylspiro-dinaphthopyran, Examples include 3-propyl spiro-dipenzobilane. These can be used alone or in combination.

The present invention is not limited to these electron-donating colorless dyes.

The electron-accepting compound (W coloring agent) used in the present invention includes a phenolic compound, an organic acid or a metal salt thereof,
Hydroxybenzoic acid esters are preferred, and specific examples include the following.

Salicylic acid, 3-isopropylsalicylic acid, 3.5-di-ter,-butylsalicylic acid, 3.5-di-α-methylbenzylsalicylic acid, 4,4'-isopropylidenediphenol, 4.4'-isopropylidene bis( 2-chlorophenol)-4,4”-isopropylidene bis(
2,6-dichlorophenol), 4,4'-isopropylidene bis(2,6-dimethylphenol), 4,4'
-isopropylidene bis(2-ter, -butylphenol), 4.4'-cyclohexylidene bisphenol, 4.4'-cyclohexylidene bis(2-methylphenol), 4-ter, -butylphenol, 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-hydroxyphenyl)acetate,
-hydroxy-3-methylphenyl) sulfite, 4
．． 4゛-diphenolsulfone, 4-isopropoxy-
4°-Hydroxydiphenylsulfone, 1,7-di(4
-hydroxyphenylthio)-3,5-dioxahebutane, phloroglycincarboxylic acid, 4-ter, -octylcatechol, 2,2'-methylenebis(4-chlorophenol), 2,2'-methylenebis(4-methyl −
6-ter-butylphenol), 2.2″-dihydroxydiphenyl, ethyl p-hydroxybenzoate, p
-propyl hydroxybenzoate, butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, p-chlorobenzyl p-hydroxybenzoate, 0-chlorobenzyl p-hydroxybenzoate, p-hydroxybenzoate Methylbenzyl, p-hydroxybenzoic u-
n-octyl, benzoic acid, zinc salicylate, 1-hydroxy-2-naphthoic acid, 2-hydroxy-6-naphthoic acid, 2-hydroxy-6-naphthoic zinc, 4-hydroxydiphenylsulfone, 4-hydroxy-4- Chlorodiphenylsulfone, 2-hydroxy-p-toluic acid, 3.5-ter, -zinc butylsalicylate, 3.5-
ter, -butyl salicyl IilIg, tartaric acid, oxalic acid, maleic acid, citric acid, succinic acid, stearic acid, 4-hydroxyphthalic acid, oxalic acid, thiooriginal derivative,
There are 4-hydroxythiophenol rust conductors and the like.

A water-soluble or water-insoluble binder is used as the binder to bind the mixture of color former and color developer onto the support sheet. Typical examples include polyvinyl alcohol, methyl cellulose, and hydroxyethyl. Cellulose, carboxymethyl cellulose, gum arabic, starch, gelatin, casein, polyvinylpyrrolidone, styrene-maleic anhydride copolymer, polyacrylic acid amide, polyacrylate, terpene resin, petroleum citrus, etc., but the present invention A particularly preferably used binder is a water-soluble binder, a typical example of which 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.

Heat-sensitive recording paper! The am ratio of each of the above-mentioned components and the binder in the recording layer when producing 2 is such that the total amount of the dibenzofuran compound represented by the general formula (1) of the compound of the present invention is from 0.5 to the color former. 10 times, preferably 1 to 4 times, and the binder is 0. 3 to 3 times, preferably 0.5 to
The color forming agent and the color developing agent, which are twice as large, are preferably dispersed separately using a dispersing machine such as a ball mill, a dyno mill, a sand mill, or a paint conditioner, and are represented by the general formula (1) related to the present invention. The dibenzofuran compound may be dispersed alone, together with a color former, or together with a color developer, and is dispersed in water or an organic medium containing a binder, preferably water in which the binder is dissolved. and crush it to 1-6μ, preferably 1μ
Make a suspension with a particle size of ~3μ. 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 using a wire bar Saka 6 to 20 so that the solid content after drying is 3 to 10 g/rd, and dry in a blow dryer at room temperature to 70°C. By doing so, W&heat record #i paper is manufactured. If necessary, an inorganic or organic filler may be added to the paint to improve the anti-fusing properties of the thermal head, the writability, etc.

(Effects of the Invention) The heat-sensitive recording paper thus obtained has excellent heat-sensitive properties, particularly color sensitivity, and is heat-resistant without any whitening phenomenon that impairs its commercial value as a heat-sensitive recording paper. The paper had excellent heat resistance and heat resistance, and was able to overcome the shortcomings of conventional heat-sensitive recording papers.

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

Example I Solution A (dye dispersion) 2-7 nylino 3-methyl-6-cyphyl γ-minofluorane ・ ・ 1 phosphorus [7 ion hydroxide ・ ・ ・ ・ 10 I nylinyl 1 fluorol aqueous solution water ・ ・ ・ ・ ・ ・ ・ ・・・・・・・・・・ 8 ・ 4 ・ 40 ・ 28 Solution B (colorant dispersion liquid III) BP^・・・・・・・・・・・・・・・5 parts zinc stearate ・ ・ ・ ・ ・・ ・ ・ ・ ・ ・
3 Part 2-Finance Franc (
Compound a melting point 89-91°C)...6 Part 4
, 4'-ferdelity piston (3-methyl-6-t
er,)゛chill)phenol ・ ・ ・ ・ ・
・ ・ ・ 1.5 parts water ・ ・ ・ ・ ・ ・
・ ・ ・ ・ ・ ・ ・ ・ ・ ・54.5 Part C
Liquid (filler dispersion liquid) 30x Calcium force - phonate component [iD liquid (binder liquid) 10 x Coal aqueous solution of vinyl 7] Mix the above compositions, A, B and C with a Dyno Mill KDL divider to determine the particle size. Grind to 1.5-3μ.

Next, the multiple liquids are mixed in the proportions shown below to form a heat-sensitive paint.

Part A・・・・・・・・・・・・・・・4 Part B・・・・・・
・・・・・・・・・16 Part C・・・・・・・・・・・・
...10 parts D ......8 parts Apply this mixed paint to the surface of high-quality paper using a Na18 wire bar so that the solid weight after drying is 7 g/rd. I applied it as shown and dried it in a blow dryer.

Feeling the heat in this way! 11! Got green paper.

Example 2 A dispersion of Liquid E was obtained in exactly the same manner as in Example 1, except that 2-benzyldibenzofuran in Liquid B was changed to dibenzofuran (compound e melting point: 83-84°C).

Next, the multiple liquids are mixed in the proportions shown below to form a heat-sensitive paint.

Afi・・・・・・・・・・・・・・・4 Part E ・・・・
・・・・・・・・・・Part 16 C・・・・・・・・・・・・
...1 part Part D ...8 parts or less Using the above additive, the same procedure as in Example 1 was carried out to obtain a thermosensitive recording paper.

Example 3 The present compound 2-benzyldibenzofuran in liquid B was
．． 3-dimethyldibenzofuran (compound melting point 91-9
A dispersion of liquid F was obtained in exactly the same manner as in the preparation of liquid B, except that the temperature was changed to 2°C.

Next, the multiple liquids are mixed in the proportions shown below to form a heat-sensitive paint.

A liquid... F　　　・　・・　・・・ C・・・・・・ D ・ ・ ・ ・ ・ Below, using the above paint, ...4 parts ...16 parts ...10 copies ...8 parts exactly the same as 1 A thermosensitive recording paper was obtained.

Example 4 The compound of the present invention 2-benzyldibenzofuran in liquid B was added to 3
．． 7-Dimethyldibenzofuran (compound has a melting point of 80-8
A dispersion of liquid G was obtained in exactly the same manner as in the preparation of liquid B, except that the temperature was changed to 1°C).

Next, the multiple liquids are mixed in the proportions shown below to form a heat-sensitive paint.

A liquid ・・・・・・・・・・・・・・・ 4 part G ・・・
・・・・・・・・・・・・16 Part C・・・・・・・・・
・・・・・・10 Part D ・・・・・・・・・・・・・・・8
The following procedure was carried out in exactly the same manner as in Example 1 using the above paint.
A thermosensitive recording paper was obtained.

The compound of the present invention 2-benzyldibenzofuran in the actual WM 5 B solution was
．． 6-dimethyldibenzofuran (compound 1 melting point 88-8
A dispersion of liquid H was obtained in exactly the same manner as in the preparation of liquid B, except that the temperature was changed to 9°C).

Next, mix the can liquid in the following proportions to prepare a heat-sensitive paint.

Solution A・・・・・・・・・・・・4 parts H・・・・・・
・・・・・・・・・Part 16 C...
- 10 parts D . . . 8 parts or less Using the above coating material, the same procedure as in Example 1 was carried out to obtain heat-sensitive recording paper.

Control Example I The present invention compound 2-benzyldibenzofuran in liquid B was
A one-liquid dispersion was obtained in exactly the same manner as in the preparation of liquid B, except that -benzylpiphenyl was used.

Next, mix the can liquid in the following proportions to prepare a heat-sensitive paint.

A liquid ・・・・・・・・・・ Engineering ・ ・ ・ ・ ・ ・ ・ ・ ・ ・
C・ ・ ・ ・ ・ ・ ・ ・ ・D
・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Examples were carried out below using the above paint, and thermal recording paper was obtained.

... 4 parts ... 16 parts ... 10 parts ... 8 parts Control example 2 The present compound 2-benzyldibenzofuran in solution B was added to 2 parts in exactly the same manner as in 1.
- A dispersion of Liquid J was obtained in exactly the same manner as in the preparation of Liquid B, except that pencil oxynaphthalene was used.

Next, mix the can liquid in the following proportions to prepare a heat-sensitive paint.

Liquid A・・・・・・・・・・・・4 parts J・・・・・・
・・・・・・・・・16 Part C・・・・・・・・・・・・
...lO parts D ......8 parts or less Using the above coating material, the same procedure as in Example 1 was carried out to obtain heat-sensitive recording paper.

Example 1, real IMf! R2, Example 3, Example 4, Example 5 and vs. jIl! The heat-sensitive recording papers obtained in Example 1 and Comparative Example 2 were each cut into specified sheets of 20 cm + width, calendered with a mini calender manufactured by Yuri Roll to achieve a smoothness of 300 seconds, and a performance test was conducted. .

The results are shown next to the actual 1N example in Table 1 and the control example in Table 2.

Table-1 Table-2 Note-1: In the color density-color energy curve graphed with R881 degrees on the vertical axis and color energy on the horizontal axis,
Heat-sensitive recording paper was colored under the conditions of a dynamic color development tester manufactured by Matsushita Electronic Components. Macbeth reflection densitometer RD-
918, and the coloring energy showing a reflection density of 1° Note-2: Note-3: Note-4: 0 was set as 51.0, and the energy at this time (■j/■12) was named the coloring sensitivity.

Under the conditions of Note 1 above, the uncolored area is It was designated as skin DO.

It represents the heat resistant storage stability after coloring of the print, and the color density D2 of the 51.0 part that was colored under the conditions described in Note 1 above was measured after 124 hours at 60°C, and the color retention rate = (D2/1.0)X
100 was determined and this was defined as heat resistance.

The color density of the uncolored portion of note 3 above was measured after 124 hours at 60° C., and this was named heat-resistant background D3.

As is clear from Tables 1 and 2, the heat-sensitive recording material of the present invention has whiter and better background fog, and has significantly improved coloring sensitivity and heat-resistant storage stability compared to heat-sensitive recording paper containing conventionally known sensitizers. , excellent performance was obtained as a thermal recording paper.

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 A heat-sensitive recording material characterized by containing a compound.