JPH0450198B2 - - 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. Further, British Patent Publication No. 2,074,335A describes the addition of hindered phenols. However, 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 present invention is characterized by containing an electron-donating colorless dye, an electron-accepting compound, an amide derivative represented by the following general formulas () to (), and a phenyl ether derivative represented by the following general formula (). This was achieved using heat-sensitive recording materials. RCONHR ₁ () RCONH-X-NHCOR () In the above formula, R represents an alkyl group that may be substituted with an aryloxy group, R ₁ and R ₂ represent an alkyl group, X represents a hexahydroxylylene residue, and a benzene ring A and B may have a chlorine atom as a substituent. In the above formula, R' is an alkyl group or an aralkyl group which may have a chlorine atom as a substituent, and Y ₁
represents a phenyl group, an alkyl group, or an aralkyl group, and Y ₂ represents a hydrogen atom or a chlorine atom when Y ₁ is a phenyl group, and represents a hydrogen atom when Y ₁ is an alkyl group or an aralkyl group. Among the alkyl groups represented by R in the above general formulas () to (), alkyl groups having 1 to 20 carbon atoms and aryloxy-substituted alkyl groups having 7 to 20 carbon atoms are more preferred. Among the alkyl groups represented by R ₁ in the above general formula (), an alkyl group having 1 to 20 carbon atoms is more preferable. Among the alkyl groups represented by R ₂ in the above general formula (), an alkyl group having 1 to 20 carbon atoms is more preferable. Among the above amide derivatives, those having a melting point of 40°C to 200°C are preferred, and those having a melting point of 70°C to 150°C are particularly preferred. In the above general formula (), the aralkyl group represented by R' preferably has 7 to 20 carbon atoms,
Particularly preferred examples include benzine group and phenethyl group. In the above general formula (), the alkyl group represented by Y ₁ preferably has 1 to 15 carbon atoms, more preferably 1 to 8 carbon atoms. Preferred examples of the aralkyl group represented by Y ₁ include benzine group, β-phenethyl group, and 2-phenylpropyl group. In the phenyl ether derivative represented by the general formula () according to the present invention, the substituent represented by Y ₁ may be substituted at any of the ortho, meta, and para positions with respect to the OR′ group, but Particularly preferred are those substituted with para. Among the above phenyl ether derivatives, 40℃~
Those with a melting point of 150°C are preferred, especially 50°C.
Those having a melting point of ~120°C are preferred. The heat-sensitive recording material containing the amide derivatives represented by the general formulas () to () and the phenyl ether derivatives represented by the general formula () according to the present invention has sufficient color density and color development sensitivity, and furthermore, the color development sensitivity decreases over time. Also, there is little scattering, and the coloring body has sufficient fastness after coloring. Next, specific examples of the amide derivative and phenyl ether derivative according to the present invention will be shown, but the present invention is not limited thereto. Examples of amide derivatives (1) Examples of general formula () Stearic acid anilide, stearic acid -p-
Chloranilide (2) Examples of general formula () Stearic acid methylamide, phenoxyacetic acid stearylamide, 2-naphthoxyacetic acid stearylamide (3) Examples of general formula () Benzoic acid stearylamide, p-chlorobenzoic acid stearylamide (4) Example of general formula () 1,3-bis(capryloylaminomethyl)
Examples of cyclohexane phenyl ether derivatives p-benzyloxybiphenyl, p-β-fu-
Netyloxybiphenyl, 3-chloro-4-benzyloxybiphenyl, pt-butylphenylbenzyl ether, 4-cumylphenylbenzyl ether, 4-cumylphenyl-p-methylbenzyl ether, 4-benzylphenyl -p-chlorobenzyl ether, etc. Examples of the electron-donating colorless dye used in the present invention include triarylmethane compounds, diphenylmethane compounds, xanthene compounds, thiazine compounds, and spiropyran compounds. 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:
There are 4,4'-bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl-leucoauramine, N-2,4,5-trichlorophenylleucoauramine, and xanthene compounds include rhodamine-B. -anilinolactam, rhodamine (p-nitroanilino)lactam, rhodamine B (p-chloroanilino)lactam, 2-
Dibenziamino-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
-ethrykiethylamino-3-chloro-6-diethylaminofluorane, 2-anylno-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, oxybenzoic acid esters, etc. Phenol compounds are particularly preferred because they are present in small amounts; No. 45-14039, 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 and 4,4'-secondary-isobutyldendiphenol. The heat-sensitive recording material according to the present invention has the general formula ()
It contains one or more amide derivatives represented by -() and one or more phenyl ether derivatives represented by general formula (). The amide derivative and phenyl ether derivative used in the present invention are used after being dispersed in a dispersion medium to a particle size of 10 μm or less using a ball mill or the like. Alternatively, the electron-donating colorless dye and/or the electron-accepting compound may be added at the same time as being dispersed in the dispersion medium using a ball mill or the like. In particular, amide derivatives are added to increase sensitivity by utilizing the eutectic effect with phenols of electron-accepting compounds. It is preferable to disperse by the method shown in 110942/1983. In particular, the latter method is superior in terms of workability and improved performance. When performing these operations, the phenyl ether derivative may be added at the same time. The electron-donating colorless dye and electron-accepting compound used in the present invention are pulverized and dispersed in a dispersion medium to a particle size of 10 μm or less. A water-soluble polymer aqueous solution having a concentration of about 1 to 10% is generally used as the dispersion medium, and dispersion is carried out using a ball mill, sand mill attritor, colloid mill, or the like. The ratio of the electron-donating colorless dye to the electron-accepting compound used is preferably between 1:10 and 1:1 by weight, and particularly preferably between 1:5 and 2:3. In addition, the amide derivative is added at a weight ratio of 20% to 300% to the electron-accepting compound,
Particularly preferably 50% or more and 150% or less. Phenyl ether derivatives also contain 20% or more of the color developer.
Added at a weight ratio of 300% or less, especially 40% or more 150
% or less is preferable. If the amount of the amide derivative and phenyl ether derivative added is less than 20%, the effect of improving sensitivity, which is the objective of the present invention, will not be sufficient, and if the amount added is more than 300%, the heat capacity of the system will increase too much. On the contrary, it causes a decrease in sensitivity. Additives are further added to the heat-sensitive coating liquid thus obtained in order to meet various requirements. Examples of additives include oil-absorbing substances such as inorganic pigments dispersed in the binder to prevent staining of the recording head during recording, and fatty acids to improve releasability from the head. ,
Metal soap etc. are added. Therefore, in general,
In addition to color formers and color developers that directly contribute to color development, pigments, wax, additives, etc. are applied to the support.
A thermosensitive recording material will be constructed. Specifically, from kaolin as a pigment, calcined kaolin, talc, waxite, diatomaceous earth, calcium carbon, aluminum hydroxide, magnesium hydroxide, magnesium carbon, titanium oxide, barium carbon, urea-formalin filler, cellulose filler, etc. Selected waxes include paraffin wax, cownabar wax, microcrystalline wax, polyethylene wax, and higher fatty acid esters. Examples of the metal soap include polyvalent metal salts of higher fatty acids, such as zinc stearate, aluminum stearate, calcium stearate, and zinc oleate. These are dispersed and applied in a binder. Water-soluble binders are generally used, such as polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, Examples include polyacrylic acid, polyacrylic acid amide, starch derivatives, casein, and gelatin. In addition, in order to impart water resistance to these binders, water-resisting agents (gelling agents, cross-linking agents) are added, or emulsions of hydrophobic polymers, specifically styrene-butadiene rubber latex, acrylic resin emulsions, etc. You can also add The coating is 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 6 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, similarly, 10% g of bisphenol A, which is an electron-accepting compound, was dispersed overnight in a ball mill with 100 g of a 5% polyvinyl alcohol aqueous solution. Furthermore, 10 g of each of the amide derivatives and phenyl ether derivatives listed in Table 1 were dispersed in a ball mill with a 50% polyvinyl alcohol aqueous solution overnight, and these four dispersions were mixed, followed by 20 g of kaolin (diyodiakaolin). Add and disperse well, then add paraffin wax emulsion 50
% 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 hour, a supercalender was applied at a linear pressure of 60 KgW/cm to obtain a coated paper. 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 to prepare Samples 1 to 5, using only one of the amide derivative and the phenyl ether derivative. 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 shown 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】

【table】

Claims (1)

[Scope of Claims] 1. Contains an electron-donating colorless dye, an electron-accepting compound, an amide derivative represented by the following general formulas () to (), and a phenyl ether derivative represented by the following general formula (). A heat-sensitive recording material. RCONHR ₁ () RCONH-X-NHCOR () In the above formula, R represents an alkyl group that may be substituted with an aryloxy group, R ₁ and R ₂ represent an alkyl group, X represents a hexahydroxylylene residue, and a benzene ring A and B may have a chlorine atom as a substituent. In the above formula, R' is an alkyl group or an aralkyl group which may have a chlorine atom as a substituent, and Y ₁
represents a phenyl group, an alkyl group or an aralkyl group, Y ₂ represents a hydrogen atom or a chlorine atom when Y ₁ is a phenyl group, and represents a hydrogen atom when Y ₁ is an alkyl group or an aralkyl group.