JPH01178488A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material having a superior thermal response and a high color forming sensitivity, by adding a specific compound to the material. CONSTITUTION:In a thermal recording material containing a normally colorless or light-colored dye precursor and a color developer coloring the dye precursor on heating as basic ingredients, a compound shown by a general formula (1) is contained. In the formula, R1 represents alkyl, R2 represents alkyl or aralkyl which may have substituents, and Ar represents aryl which may have substituents. A compound having a melting point of 70-160 deg.C is practically preferable from among the compounds shown by the formula (1). The compound shown by the formula (1) is added to the color developer by the amount of 5-400wt.%, but particularly a preferably amount is 20-300wt.%. An addition amount less than 5wt.% or that more than 400wt.% preferable from among the compounds shown cannot impart a sufficient effect. As the color developer, an electron acceptable compound is used, and especially a phenol derivative, an aromatic carboxylic acid derivative, an N,N'-diaryl tiourea derivative, a polyvalent metal salt such as a zinc salt of organic compound, and the like are preferably used.

Description

DETAILED DESCRIPTION OF THE INVENTION (A>Field of Industrial Use) The present invention relates to a heat-sensitive recording material 1 which is excellent in thermal response and has high color development sensitivity.

(B) Conventional technology Heat-sensitive recording materials generally have a heat-sensitive recording layer on a support, the main components of which are an electron-donating, usually colorless or light-colored dye precursor and an electron-accepting color developer. By heating with a head, hot pen, laser beam, etc., the dye precursor and developer react instantaneously and a recorded image is obtained. has been disclosed. This type of heat-sensitive recording material has the advantages of being able to record with a relatively simple 8-position system, being easy to maintain, and generating no noise, and is useful for measurement recorders, facsimile machines, printers, and computer terminals. It is used in a wide range of fields, including machines, labels, and automatic ticket vending machines. Particularly in the field of facsimile, the demand for heat-sensitive methods has increased significantly, and along with this, attempts have been made to increase speed, miniaturize devices, and lower prices to reduce transmission costs.

As a result, the energy required for semi-processing for image printing continues to decline in recent devices. Therefore, there has been a strong demand for the development of highly sensitive heat-sensitive recording materials with high thermal responsiveness that can cope with such higher speed and lower energy facsimiles. In high-speed recording, the tiny amount of thermal energy released from the thermal head in an extremely short period of time (usually less than 1 millisecond) is used as efficiently as possible for the color reaction.
It is necessary to form a colored image with high density.

As a means for achieving the above object, it has been proposed to use a thermofusible substance with a relatively low melting point as a color development accelerator or sensitizer together with a dye precursor and a color developer. For example, naphthol derivatives are used in JP-A-57-64593 and JP-A-58-87094;
No., JP-A-57-185187, JP-A-57-191
No. 089, JP-A-58-110289@, JP-A-59-
No. 15393 discloses naphthoic acid derivatives in JP-A No. 15393.
No. 72499 and Japanese Unexamined Patent Publication No. 58-87088 propose the use of ether and ester derivatives of phenolic compounds.

However, the heat-sensitive recording materials produced using these methods are still insufficient in terms of thermal response and color development sensitivity.
It is.

(C) Purpose of the Invention The purpose of the present invention is to obtain a heat-sensitive recording material which is excellent in thermal responsiveness and has high color development sensitivity.

(D) Structure of the Invention A heat-sensitive recording material whose basic components are a normally colorless to light-colored dye precursor and a color developer that causes the dye precursor to develop color when heated, contains a compound represented by the following formula. As a result, a heat-sensitive recording material with excellent thermal response and high color development sensitivity could be obtained.

(Left below) General formula % Formula % However, in the above formula, R1 is an anolyl group, Rz is a furkyl group, an aralkyl group which may have a substituent, and Ar may have a substituent. Indicates an aryl group.

Among the compounds of the above formula, those having a melting point in the range of 70 to 160°C are practically preferred.

Specific examples of the compounds of the present invention include: 2-Edylacetoacetanilide 2-Propylacetoacetic anilide.

2-Butylacetoacetic anilide 2-propylacetoic acid v! 1 (o-toluicide) vinegar (
0-phenetidide) 2-ethylacetoacetate m (0-chloroanilide) 2-butylacetoacetate (p-chloroanilide) 2-butylacetoacetate 1
~ Vinegar m (p-toluicide) 2-propylacetoic acid M (p
-chloroanilide) 2-benzylacetoic acid M (p-n-
butylanilide) 2-benzylacetoic acid@(0-chloroanilide) 2-(
p-methylbenzyl) acetovine r! 1(0-anisidide) 2-(p-methoxybenzyl)acetoacetic acid (p-anisidide) 2-(2'-phenethyl)acetoacetic acid anilide 2-benzylacetoacetic acid (0-7nisidide) 2-benzylacetoacetic acid M ( p-anisidide) 2-hexylacetoacetic acid anilide 2-benzyl-3-oxopentaneyl anilide 2-ethyl-3-oxohexanoic acid anilide 2-propyl-3-
Examples include oxo-5-methylhexanoic acid anilide, but the present invention is not limited thereto.

Note that the compound of the present invention can be synthesized at low cost by a known method and can be easily purified.

The compound of the present invention is added in an amount of 5 to 400% by weight, and preferably 20 to 300% by weight. If the amount added is less than 5% by weight or more than 400@i%, sufficient effects cannot be obtained.

The dye precursor used in the present invention is not particularly limited as long as it is used in general pressure-sensitive recording paper, heat-sensitive recording paper, etc. Specific examples include (1) triarylmethane compounds such as 3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (crystal violet lactone), 3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (crystal violet lactone); -dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenyl)-3-(1,2-dimethylindole-
3-yl)phthalide, 3-(p-dimethylaminophenyl)-3-(2-methylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-3-(2
-phenylindol-3-yl)phthalide, 3,3-
Bis-(1,2-dimethylindol-3-yl)-5
-dimethylaminophthalide, 3,3-bis-(1,2-
dimethylindol-3-yl)-6-dimethylaminophthalide, 3,3-bis-(9-ethylcarbazole-
3-yl)-5-dimethylaminophthalide, 3,3-bis-(2-phenylindol-3-yl)-5-dimethylaminophthalide, 3-D-dimethylaminophenyl-3-(1-methyl Pyrrole-dimethylaminophthalide, etc.: (2) Diphenylmethane compounds such as 4,4'-bis-dimethylaminobenzhydrylbenzyl ether, N-herophenylleukoolamine, N-2.4.5-tri Chlorophenylleucoolamine, etc.: (3) As xanthene compounds, rhodamine B-anilinolactam, rhodamine B-p-chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-octyl Aminofluorane, 3-diethylamino-7-phenylfluorane, 3-diethylaminofluorane (3,4
-dichloroanilino)fluoran, 3-diethylamino-7-(2-chloroanilino)fluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-
piperidino-6-methyl-7-anilinofluorane, 3
-ethyl-tolylamino-6-methyl-7-anilinofluorane, 3-ethyl-tolylamino-6-methyl-7
-Phenylfluorane, 3-diethylamino-7-(
4-nitroanilino)fluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3-(N-methyl-N-propyl)amino-6-medy-7-anilinofluorane, 3-(N- ethyl-isopropyl)
Amino-6-methyl-7-anilinofluorane, 3-(
N-ethyl-N-tetrahydrofurfuryl)amino-6
-Di(4)thiazine compounds such as methyl-7-anilinofluorane, benzoyl leucomethylene blue, p
-Nitrobenzoylleucomethylene blue, etc.: (5) As a spiro compound, 3-methyl-spirodinaf 1 to
Pyran, 3-ethyl-spiro-dinaphthopyran, 3,3
'-Cyclolose spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methylnaphtho-(3-
Examples include methoxy-benzo) spiropyran, 3-propyl-spiro-dibenzopyran, and mixtures thereof.

These are determined by the application and desired properties.

As the color developer, acids and 14 substances generally used in thermal paper, that is, electron-accepting compounds, are used, and in particular,
Phenol derivatives, aromatic carboxylic acid derivatives, N,N”
Preferred are -diarylthio'urea derivatives, multifunctional metal salts such as zinc In, etc., which are organic compounds.

14 is preferably a phenol derivative, specifically p-phenylphenol, p-hydroxyaretophenone, 4-hydroxy-4'-methyldiphenylsulfone, 4-hydroxy-4'-isopropo4nididiphenylsulfone. , 4-hydroxy-4'-benzenesulfonyloxydiphenylsulfone, 1,1-bis(p-hydroxyphenyl)propane, 1,1-bis(p-hydroxyphenyl)pentane, 1,1-bis(p-hydroxyphenyl) ) hexane, 1,1-bis(p-hydroxyphenyl)cyclohexane, 2,2-bis(p-hydroxyphenyl)propane, 2,2-bis(p-hydroxyphenyl)hexane, 1,1-bis(p- hydroxyphenyl)-2-ethylhexane, 2,2-bis(3-
Chloro-4-hydroxyphenyl)propane, 1.1-
Bis(P-hydroxyphenyl)-1-phenylethane, 1,3-di(2-(p-hydroxyphenyl)-2-
propyl)benbin, 1,3-di(2-(3,4-dihydroxyphenyl)-2-propyl)benzene, 1,4
-di(2-(p-hydroxyphenyl)-2-propyl)benzene, 4.4'-dihydroxydiphenyl ether, 4.4'-dihydroxydiphenyl sulfone, 3.
3゛-dichloro-4,4'-dihydroxydiphenylsulfone, 3゜3゛-diallyl-4,4'-dihydroxydiphenylsulfone, 3,3'-dichloro-4,4'-
Dihydroxydiphenyl sulfide, 2,2-bis(4
-Hydroxyphenyl)^1'reL methyl, 2,2'
-Bis(4-hydroxyphenyl)butyl acetate, 4,4
'-Thiogos(2-1-butyl-5-methylphenol), benzyl p-hydroxybenzoate, p-hydroxybenzoate ff1M [10benzyl, dimethyl 4-hydroxyphthalate, benzyl gallate, stearyl gallate,
These include salicylanilide, 5-chlorosalicylanilide, and the like.

As a binder, water-soluble binders such as starches, hydroxyethyl cellulose, methylcellulose, cimedyl cellulose, gelatin, cavin, polyvinyl alcohol, modified polyvinyl alcohol, styrene-maleic anhydride copolymer, ethylene-maleic anhydride copolymer, etc. , a styrene-butadiene copolymer, an acrylonitrile loop dashiene copolymer, an acrylic methyl loop dashiene copolymer, and other latex-based water-soluble binders.

Examples of pigments include diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium fermentation, zinc oxide, silicon oxide, aluminum hydroxide, urea-formalin resin, and the like.

In addition, higher fatty acid metal salts such as zinc stearate and calcium stearate, waxes such as paraffin, oxidized paraffin, polyethylene, oxidized polyethylene, stearic acid amide, and castor wax are used to prevent head wear and stickiness. Examples include dispersants such as sodium dioctyl sulfosuccinate, ultraviolet absorbers such as benzophenone and benzotriazole, surfactants, and fluorescent dyes.

As the support used in the heat-sensitive recording material according to the present invention, paper, various nonwoven fabrics, plus deck film, synthetic paper, metal foil, etc., or a composite sheet of a combination of these can be arbitrarily used.

In paper, it is preferable to use paper that has been internally added or subbed with inorganic or organic pigments.

(E) Examples Next, the present invention will be roughly explained in detail using examples.

Note that all parts and percentages shown below are based on heavy ω.

〔Example〕

3-diethylamino-6-methyl-7, a dye precursor
- 20 parts of anilinofluorane and 80 parts of 2.5% polyvinyl alcohol in water were ground in a ball mill for 24 hours, and the dye dispersion was mixed with 50 parts of 2,2-bis(4-hydroxyphenyl)propane. was ground with 200 parts of a 2.5% polyvinyl alcohol aqueous solution in a ball mill for 24 hours to obtain a color developer dispersion.

On the other hand, 2-benzylacetoacetic acid M (o-chloroanilide)
25 parts were ground together with 100 parts of a 2.5% polyvinyl alcohol aqueous solution in a ball mill for 24 hours to obtain a dispersion of the compound of the present invention.

After mixing the above three types of dispersions, the following were added under stirring and mixed well to prepare a heat-sensitive coating liquid.

Calcium carbonate 50% aqueous dispersion 100 parts Zinc stearate 40% aqueous dispersion 25 parts 10% polyvinyl alcohol aqueous solution 220 parts Water 180
8[ri(q) coating liquid tsuboa 50'J/rrt
5.6 as the amount of solids smeared on the base paper! l? A heat-sensitive recording material was created by smearing it on the tip and drying it.

[Comparative Example 1] A heat-sensitive recording material was prepared in the same manner as in the example except that 2-benzylacetoacetic acid M (0-chloroanilide) in the example was changed to N-hydroxymethylstearic acid amide.

[Comparative Example 2] The 2-benzylacetoacetic acid (〇-chloroanilide) dispersion in Example was not added, and the solid content was reduced to 99%.
A heat-sensitive recording material was prepared in the same manner as in the example except that /rd was used.

The heat-sensitive recording materials obtained in Evaluation Examples and Comparative Example 1.2 were calendered so that the Bekk smoothness of the heat-sensitive coated surface was 400 to 500 seconds. A printing test was conducted using the head voltage 1.
6.0V, energizing time 1゜2.1.6.2.0ms 3
Printing was performed under these conditions, and the G degree of each color was measured using a Macbeth RD-514 type foul densitometer. The results are shown in Table 1.

(Hereinafter in the margin) Table 1 (Hereinafter in the margin) (F) Effect As is clear from the results in Table 1, by containing the compound of the present invention, a heat-sensitive recording material with excellent thermal response and high color development sensitivity can be produced. I was able to get it.

Claims (1)

[Claims] A heat-sensitive recording material whose basic components are a normally colorless or light-colored dye precursor and a color developer that causes the dye precursor to develop color when heated, containing a compound represented by the following general formula: A heat-sensitive recording material characterized by: General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ However, in the above formula, R_1 is an alkyl group, R_2 is an alkyl group, an aralkyl group that may have a substituent,
r represents an aryl group which may have a substituent.