JPH0354071B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive recording material, and particularly to a heat-sensitive recording material with improved color development. Heat-sensitive recording materials using an electron-donating colorless dye and an electron-accepting compound are disclosed in Japanese Patent Publications No. 14039-1982, Japanese Patent Publication No. 4160-43-1972, and the like. The minimum performance that such a heat-sensitive recording material should have is (1) sufficient color density and color development sensitivity, (2) no fogging (color development phenomenon during storage before use), and (3) The coloring material must have sufficient fastness after coloring, but currently no product has been obtained that completely satisfies these requirements. Particularly in recent years, as thermal recording systems have become faster, research on the above (1) has been intensively conducted. One way to do this is to raise the melting point of the electron-accepting compound itself from 60 to 100°C. However, it is difficult to control the melting point of phenolic compounds, which are currently the most widely used electron-accepting compounds, and the phenolic compounds themselves are expensive and impractical. Other methods include the combined use of organic acids and phenolic compounds as electron-accepting substances, as described in Japanese Patent Publications No. 49-17748 and No. 51-39567;
Alternatively, it is described that a polyvalent metal salt of a compound having an alcoholic hydroxyl group is used. Furthermore, Japanese Patent Publication No. 51-29945 describes the use of a copolymer of hydroxyethyl cellulose and maleic anhydride. Also, Japanese Patent Publication No. 51-27599 and Japanese Patent Publication No. 48-19231
The issue states that waxes are added. Furthermore, JP-A-49-34842, JP-A-49-115554
No., JP-A-50-149353, JP-A-52-106746,
JP-A-53-5636, JP-A-53-11036, JP-A-Sho
No. 53-48751 and JP-A-56-72996, etc., disclose thioacetanilide, phthalonitrile, acetamide, di-β-naphthyl-p-phenylenediamine, fatty acid amide, acetoacetanilide, diphenylamine, benzamide, carbazole, etc. or 2,3-di-m-
It has been described that thermofusible substances such as tolylbutane, 4,4'-dimethylbiphenyl, or carboxylic acid esters such as dimethyl isophthalate, diphenyl phthalate, dimethyl terephthalate, etc. are added as sensitizers. Furthermore, British Patent Publication No. 2074335A describes the addition of hindered phenols. However, the heat-sensitive recording materials produced using these methods are insufficient in color density and color sensitivity. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a heat-sensitive recording material which has sufficient color density and color sensitivity and satisfies other requirements. The object of the present invention has been achieved by a heat-sensitive recording material characterized by containing an electron-donating colorless dye, an electron-accepting compound, and an acetalinide derivative represented by the following general formula (). The substituent represented by R in the above formula represents a phenyl group, a phenoxy group or a naphthyloxy group, and the benzene ring A may have a substituent. Examples of preferred substituents on the benzene ring include alkyl groups, aralkyl groups, halogen atoms, hydroxy groups, and alkoxy groups. The substituent represented by R in the above general formula may further have a substituent. Among the substituents represented by R in the above general formula (), phenyl group, phenoxy group, naphthyloxy group, alkyl-substituted phenyl group, halgen-substituted phenyl group, and halogen-substituted phenoxy group are preferable, particularly phenyl group, phenoxy group, and tolyl group. A group, a chlorophenyl group, and a chlorophenoxy group are preferable. In the above general formula, among the substituents on the benzene ring, a halogen atom, an alkyl group having 1 to 10 carbon atoms, and an alkoxy group having 1 to 10 carbon atoms are more preferable. These substituents on the benzene ring may substitute 1 to 5 hydrogen atoms on the benzene ring, but one in which one hydrogen atom is substituted is particularly preferred. In addition, when one substituent is substituted, the position of the substituent may be any of the ortho, meta, and para positions with respect to the NHCOCH ₂ R group, but para-substitution is particularly preferred. Among the above acetanilide derivatives, 40℃～200℃
It is preferable to have a melting point of 80°C to 170°C.
Those having a melting point of °C are preferred. The heat-sensitive recording material containing the acetanilide derivative represented by the general formula according to the present invention has sufficient color density and color development sensitivity, has little decrease in color development sensitivity over time and fog, and has sufficient fastness of the color former after color development. . Next, specific examples of the acetanilide derivatives according to the present invention will be shown, but the present invention is not limited thereto. (1) N-phenylacetylaniline (2) N-phenylacetyl-p-toluidine (3) N-phenylacetyl-p-anisidine (4) N-phenylacetyl-p-chloroaniline (5) N -p-Tolylacetylaniline (6) N-p-chlorophenylacetylaniline (7) N-phenoxyacetylaniline (8) N-phenoxyacetyl-p-toluidine (9) N-phenoxyacetyl- p-anisidyl (10) N-phenoxyacetyl-p-chloroaniline (11) N-p-chlorophenoxyacetylaniline (12) N-β-naphthyloxyacetylaniline (13) N-p-chlorophenylacetyl -m-toluidine (14) N-p-chlorophenylacetyl-o-toluidine, etc. Examples of the electron-donating colorless dye used in the present invention include triarylmethane compounds, diphenylmethane compounds, xanthene compounds, and thiazine compounds. , spiropyran compounds, etc. are used. To illustrate some of these, triarylmethane compounds include 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (i.e., crystal violet lactone);
3,3-bis(p-dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenyl)-3
-(1,3-dimethylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-3
-(2-methylindol-3-yl)phthalide,
etc., and diphenylmethane compounds include:
4,4'-bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl-leuco-
xanthene compounds include rhodamine-B-anilinolactam, rhodamine (p-nitroanilino)lactam, and rhodamine B (p-chloroanilino)lactam. , 2-
Dibenzylamino-6-diethylaminofluorane, 2-anilino-6-diethylaminofluorane, 2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6
-cyclohexylmethylaminofluorane, 2-
o-chloroanilino-6-diethylaminofluorane, 2-m-chloroanilino-6-diethylaminofluorane, 2-(3,4-dichloroanilino)-6-diethylaminofluorane, 2-octylamino-6-diethylaminofluorane ,2
-dihexylamino-6-diethylaminofluorane, 2-m-trifluoromethylanilino-6-
Diethylaminofluorane, 2-butylamino-
3-chloro-6-diethylaminofluorane, 2
-ethoxyethylamino-3-chloro-6-diethylaminofluorane, 2-anilino-3-chloro-6-diethylaminofluorane, 2-diphenylamino-6-diethylaminofluorane, 2
-anilino-3-methyl-6-diphenylaminofluorane, 2-phenyl-6-diethylaminofluoran, etc. Thiazine compounds include benzoylleucomethylene blue, p-nitrobenzylleucomethylene blue, etc. The compounds include 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3,3'-dichloro-spiro-dinaphthopyran, 3-benzylspiro-dinaphthopyran, 3-
Examples include methyl-naphtho-(3-methoxy-benzo)spiropyran and 3-propyl-spiro-dibenzopyran. These may be used alone or in combination. Examples of electron-accepting compounds include phenol compounds, organic acids or their metal salts, and oxybenzoic acid esters. Phenol compounds are particularly preferred because they require only a small amount. −14039, Special Publication No. 51-29830
It is described in detail in the issue. Specifically, 4-
Tertiary butylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, α-
Naphthol, β-naphthol, methyl-4-hydroxybenzoate, 2,2'-dihydroxybiphenyl, 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), 4,4'-isopropylidene bis (2-methylphenol),
1,1-bis-(3-chloro-4-hydroxyphenyl)cyclohexane, 1,1-bis-(3-
Examples include chloro-4-hydroxyphenyl)-2-ethylbutane, 4,4'-secondary-isobutylidene diphenol, and 4-hydroxybenzoic acid benzyl ester. The heat-sensitive recording material according to the present invention has the general formula ()
Although it contains one or more acetanilide derivatives represented by the following, low melting point compounds other than those of the present invention can also be used in combination. Next, a specific example of the manufacturing method will be described. The most common manufacturing method for heat-sensitive recording materials is
The above-mentioned colorless electron-donating dye and electron-accepting compound are each separately dispersed in a 1-10% by weight water-soluble polymer solution using a ball mill, sand mill, etc., and then mixed. , talc, calcium carbonate, and other inorganic pigments are added to create a coating liquid. If necessary, a paraffin wax emulsion, a latex binder, a sensitivity improver, a metal soap, an ultraviolet absorber, etc. can be added thereto. Coating fluids are most commonly applied onto base paper. Generally, the coating amount is 2 to 10 g/m ² as a solid content, with the lower limit determined by the density during color development by heating, and the upper limit determined mainly by economic constraints. Examples will be shown below, but the present invention is not limited only to these examples. Example (1) Preparation of samples 1 to 4 2-anilino-3, which is an electron-donating colorless dye
-Chloro-6-diethylaminofluorane 5g
5% polyvinyl alcohol (Sapon value 99%,
The mixture was dispersed in a ball mill with 50 g of an aqueous solution (degree of polymerization: 1000) overnight. On the other hand, 20 g of bisphenol A, which is an electron-accepting compound, was similarly dispersed with 200 g of a 5% polyvinyl alcohol aqueous solution in a ball mill overnight, and further, 20 g of the acetanilide derivatives shown in Table 1 were dispersed with a 5% polyvinyl alcohol aqueous solution in a ball mill,
After mixing these three types of dispersions, 20g of kaolin (diyodia kaolin) was added and dispersed well, and then 50g of paraffin wax emulsion was added.
% dispersion (Chukyo Yushi Cellosol #428) was added to prepare a coating liquid. The coating liquid was applied onto a base paper having a basis weight of 50 g/m ² so that the solid content was 6 g/m ² ,
After drying at 60° C. for 1 minute, a coated paper was obtained by supercalendering at a linear pressure of 60 KgW/cm. Coated paper is heated by facsimile
Color was developed by heating at 35 mJ/cm ² and the color density was determined. The results are shown in Table 1. (2) Preparation of Comparative Samples 1 to 2 A similar test was conducted using exactly the same formulation as that used for preparing Samples 1 to 4, except that only the acetanilide derivative was replaced with a compound other than the present invention shown in Table 1. The results are also shown in Table 1. It can be seen from Table 1 that the recording material according to the invention clearly has a high sensitivity. Furthermore, when the fog density in Table 1 exceeds 0.13, the commercial value is significantly reduced. From this point of view as well, it was found that the electron-accepting compound of the present invention provides an extremely excellent heat-sensitive recording sheet. 【table】

Claims (1)

[Scope of Claims] 1. A heat-sensitive recording material characterized by containing an electron-donating colorless dye, an electron-accepting compound, and an acetanilide derivative represented by the following general formula (). The substituent represented by R in the above formula represents a phenyl group, a phenoxy group or a naphthyloxy group, and the benzene ring A may have a substituent.