JPH04213368A - Fluorene compound and thermal recording medium using the compound - Google Patents

Abstract

PURPOSE:To improve whiteness, storage stability and color-developing properties by reacting a fluorene compd. having a hydroxyl group at the 3-position with a tert. alkyl chloroformate in the presence of a base. CONSTITUTION:A fluorene compd. of formula III is obtd. by reacting a fluorene compd. of formula I (wherein R is a 4-12C tert. alkyl; R1 to R11 are each H, a halogen, a 1-12C alkyl, a 1-12C alkoxyl, etc.) having a hydroxyl group at the 3-position with a tert. alkyl chloroformate of formula II in an amount at least equipvalent to the hydroxyl group. A coating liq. for a thermal recording layer is obtd. by dispersing 100 pts.wt.compound (III), a colorless or pole dye precursor, 1-50 pts.wt. acidic substance developing color when it is brought into contact with this precursor, and a binder in water. A support is coated with this coating liq. in a coating of 2-12g/m<2> and is dried to obtain a thermal recording medium.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a fluoran compound useful as a dye precursor, etc., and a heat-sensitive recording material using the fluoran compound, and particularly, when used as a dye precursor for a heat-sensitive recording material, it has high whiteness and The present invention relates to a fluoran compound that provides a recording medium that has excellent storage properties such as heat resistance, moisture resistance, chemical resistance, and plasticizer resistance, and is also excellent in color development.

0002

[Prior Art] A thermosensitive recording material that utilizes a coloring reaction between a colorless or light-colored dye precursor and an organic or inorganic acidic substance to obtain a recorded image by bringing the two coloring substances into contact with each other using heat is well known. ing. Recently, with the remarkable progress of thermal recording methods, the fields and forms of their use are diversifying, and they are being used not only as recording media for thermal facsimiles and thermal printers, but also for new applications such as POS (Point of Sales) labels. Its use is also rapidly increasing.

[0003] However, such heat-sensitive recording materials generally have the disadvantage that the image area may change color or fade when stored in a high temperature or high humidity environment, or when it comes into contact with fingerprints, diazo copies, cellophane tape, felt-tip pens, ink, etc. There is. Also,
If a synthetic resin product comes into contact with a heat-sensitive recording material for a long period of time, the image area may change color or fade due to the plasticizer contained in the synthetic resin.
There is also the drawback that the blank areas develop color.

[0004] In order to improve the above-mentioned drawbacks, methods of providing a protective layer of various polymer compounds on the heat-sensitive recording layer have been proposed and put into practical use. However, the method of providing a protective layer causes a decrease in image density, and does not necessarily provide sufficient effects in terms of heat resistance, moisture resistance, chemical resistance, or plasticizer resistance. There is a strong demand for improvement.

[0005]

[Problems to be Solved by the Invention] In view of the current situation, the present inventors have developed a method that has a high degree of whiteness, hardly causes discoloration of the image area even when stored in a high temperature or high humidity environment, and that is free from chemicals. In order to obtain a highly sensitive heat-sensitive recording material that is free from discoloration in image areas and fogging in blank areas due to plasticizers and plasticizers, various studies have been carried out, particularly regarding the dye precursors constituting the heat-sensitive recording layer. As a result, it was discovered that a heat-sensitive recording material having such characteristics can be obtained by using a fluoran compound represented by the following general formula [Chemical formula 1], and the present invention was completed.

[0006]

[Means for Solving the Problems] The present invention is based on the following general formula [
A heat-sensitive recording material comprising a heat-sensitive recording layer containing a fluoran compound represented by formula 1], a colorless to light-colored dye precursor, and an acidic substance capable of coloring upon contact with the dye precursor on a support. In, the dye precursor is represented by the following general formula [
This is a heat-sensitive recording material characterized by containing at least one kind of fluoran compound represented by Chemical Formula 1.

[0007]

[Chemical formula 1]

[In the formula, R represents a C4-12 tertiary alkyl group, and R1 to R11 each represent a hydrogen atom, a halogen atom, a C1-12 alkyl group, a C1-12 alkoxyl group, a hydroxyl group, a nitro group, -N (R12) (R13
), -O (CO)OR14, or -O(CO)R1
5 is shown. However, R12 and R13 are each a hydrogen atom;
C1-12 alkyl group; C4-12 cycloalkyl group; halogen atom, C1-6 alkyl group, C1-12 alkyl group;
Aralkyl group optionally substituted with 6 alkoxyl group; halogen atom, C1-6 alkyl group, C1
-6 represents an aryl group which may be substituted with an alkoxyl group, and R12 and R13 may form a pyrrolidino group, piperidino group or hexamethyleneimino group together with the adjacent nitrogen atom. Further, R14 represents a C1-12 alkyl group; a benzyl group; an aryl group which may be substituted with a halogen atom, a C1-6 alkyl group, or a C1-6 alkoxyl group, and R15 represents a C1-12 alkyl group; Benzyl group; represents an aryl group which may be substituted with a halogen atom, a C1-6 alkyl group, or a C1-6 alkoxyl group, -N (R16)(R17). In addition, R16 and R17 are each a hydrogen atom; C1~
12 alkyl group; C4-12 cycloalkyl group; halogen atom, C1-6 alkyl group, C1-6
an aralkyl group which may be substituted with an alkoxyl group;
Halogen atom, C1-6 alkyl group, C1-6
represents an aryl group which may be substituted with an alkoxyl group, and R16 and R17 may form a pyrrolidino group, piperidino group or hexamethyleneimino group together with adjacent nitrogen atoms. ]

[0009]

[Function] The fluoran compound represented by the above general formula [Formula 1] is a new compound, and itself is a stable, almost colorless compound that is useful as a dye precursor for various recording media. Such a compound has excellent properties in that it can develop color even in the absence of an acidic substance when heated at a high temperature, can lower the coloring temperature by using an acidic substance, and can provide a robust image. Furthermore, the heat-sensitive recording material of the present invention has an important feature in that at least one of such fluoran compounds is used as a dye precursor constituting the heat-sensitive recording layer. Even if the image area is stored in a high temperature or high humidity environment, the image area will not change color or fade, and even if it comes into contact with chemicals or plasticizers, the image area will not change color or the blank area will become foggy. The result is a heat-sensitive recording medium with high sensitivity.

[0010] The reason why such excellent properties can be obtained by applying the fluoran compound represented by the above general formula [Chemical formula 1] to a heat-sensitive recording medium is not necessarily clear, but it is speculated as follows. Ru. In other words, the coloring reaction between the above-mentioned specific fluoran compound and an acidic substance includes a decarboxylation reaction, and is an irreversible reaction that does not normally return to a colorless compound. Therefore, discoloration due to heat, humidity, plasticizers, etc. It is thought that it will not come. It is also assumed that stable tertiary carbonium ions are produced as intermediates during decarboxylation in the color reaction, and this is thought to provide a highly sensitive recording medium.

The fluoran compound of the present invention having the above-mentioned excellent properties can be synthesized by various methods such as those described below. ■ As shown in the following reaction formula [Chemical formula 2], by reacting a fluoran compound having a hydroxyl group at the 3-position with a tertiary alkyl ester of chloroformic acid in the presence of a base,
The desired fluoran compound can be easily synthesized in high yield and purity at a relatively low cost. In addition, a solvent can also be used in this reaction as necessary.

0012

[Case 2]

[In the formula, R, R1 to R11 each have the above-mentioned meanings. ] In addition, by using a fluoran compound having a hydroxyl group other than the 3-position as a starting compound and reacting it with a tertiary alkyl ester of chloroformic acid in an amount equivalent to or more than the hydroxyl group, a plurality of corresponding -O(CO)OR( However, R represents a tertiary alkyl group.) It is also possible to synthesize a fluoran compound having a tertiary alkyl group.

■ As shown in the following reaction formula [Chemical formula 3], 3
The desired fluoran compound can be synthesized by reacting a fluoran compound having a hydroxyl group at the position with a ditertiary alkyl dicarbonate using an acid or base and a solvent if necessary. In this case, as in the case (2) above, if a fluoran compound having a hydroxyl group other than the 3-position is used as a starting compound and reacted with an equivalent or more amount of dicarbonic acid ditertiary alkyl ester, the corresponding plurality of -O( CO)O
A fluoran compound having R is obtained.

[0015]

[Chemical formula 3]

[In the formula, R, R1 to R11 each have the above-mentioned meanings. ]

■ A fluoran compound having a hydroxyl group at the 3-position is reacted with phosgene or chloroformic acid trichloroester to form a fluoran compound having -O(CO)Cl at the 3-position, and then a tertiary alcohol is allowed to react with this. The desired fluoran compound can be synthesized.

Specific examples of the fluoran compound represented by the general formula [Formula 1] are shown below, and among these, "R"
A compound in which the substituent represented by is a tert-butyl group is more preferably used because a heat-sensitive recording material particularly excellent in color development can be obtained.

3,6-di(tert-butoxycarboxy)fluoran, 3,6-di(1,1-dimethylpropoxycarboxy)fluoran, 3,6-di(1-methyl-1-ethylbutoxycarboxy)fluoran, 3,6
-di(tert-butoxycarboxy)-4,5-dimethylfluorane, 3,6-di(tert-butoxycarboxy)-1,8-dimethylfluorane, 3,6-di(
tert-butoxycarboxy)-2,7-diethylfluorane, 3,6-di(tert-butoxycarboxy)-1,5-diethylfluorane, 3,6-di(1,1
-dimethylpropoxycarboxy)-2,7-diethylfluorane, 3,6-di(tert-butoxycarboxy)-2,4,5,7-tetrachlorofluorane, 3,
6-di(tert-butoxycarboxy)-2,4,5
, 7-tetrabromofluorane, 3,6-di(tert
-butoxycarboxy)-2,4,5,7-tetraiodofluorane, 3,6-di(tert-butoxycarboxy)-1,8-dimethyl-3',4',5',6'-
Tetrachlorofluorane, 3,6-di(tert-butoxycarboxy)-3',4',5',6'-tetrabromofluorane, 3,6-di(1,1-dimethylpropoxycarboxy)-2 , 7-dibromofluorane, 3,
6-di(1,1-dimethylpropoxycarboxy)-4
,5-dinitrofluorane, 3,6-di(1,1-diethylhexoxycarboxy)-3',4',5',6
'-tetrachlorofluorane, 3,6-di(tert-
butoxycarboxy)-2,7-dibromofluorane,
3,6-di(tert-butoxycarboxy)-4,5
-dinitrofluorane, 3,6-di(tert-butoxycarboxy)-2,7-didecylfluorane, 3,6
-di(tert-butoxycarboxy)-2-dodecyl-8-methylfluorane, 3,6-di(tert-butoxycarboxy)-6'-butoxyfluorane, 3,6
-di(tert-butoxycarboxy)-4'-methoxyfluorane, 3,6-di(tert-butoxycarboxy)-4'-decaoxyfluorane, 3-(tert-butoxycarboxy)-4'-decaoxyfluorane,
-butoxycarboxy)-6-methoxyfluorane, 3
-(tert-butoxycarboxy)-7-methoxyfluorane, 3,6-di(1,1-dimethylpropoxycarboxy)-6'-butoxyfluorane, 3-(tert-butoxycarboxy)-7-methoxyfluorane, 3,6-di(1,1-dimethylpropoxycarboxy)-6'-butoxyfluorane,
t-butoxycarboxy)-6-ethoxy-2,7-dioctylfluorane, 3-(1,1-dipropylbutoxycarboxy)-6-methoxyfluorane, 3-(te
rt-butoxycarboxy)-6-ethoxy-2,7-
Dibenzylfluorane, 3-(tert-butoxycarboxy)-6-methoxycarboxyfluorane, 3-(
tert-butoxycarboxy)-7-methoxycarboxyfluorane, 3-(tert-butoxycarboxy)-6-decaoxycarboxyfluorane, 3-(te
rt-butoxycarboxy)-6-di(methyl)aminofluorane, 3-(tert-butoxycarboxy)-
6-di(ethyl)aminofluorane, 3-(tert-
butoxycarboxy)-7-di(ethyl)aminofluorane, 3-(tert-butoxycarboxy)-6-di(butyl)aminofluorane, 3-(tert-butoxycarboxy)-6-di(dodecyl)aminofluorane Orane, 3-(tert-butoxycarboxy)-6-piperidinofluorane, 3-(tert-butoxycarboxy)-6-(N-ethyl-N-isopentyl)aminofluorane, 3-(tert-butoxycarboxy) )-6-
(N-cyclohexyl-N-methyl)aminofluorane, 3-(tert-butoxycarboxy)-6-phenoxycarboxyfluorane, 3-(tert-butoxycarboxy)-6-benzyloxycarboxyfluorane, 3-(1 ,1-dimethylhexaoxycarboxy)
-6-decaoxycarboxyfluorane, 3-(ter
t-butoxycarboxy)-6-butylcarboxyfluorane, 3-(tert-butoxycarboxy)-6-
phenylcarboxyfluoran, 3-(tert-butoxycarboxy)-6-di(methyl)aminocarboxyfluoran, etc.

[0020] Of course, the present invention is not limited to these compounds, and two or more fluoran compounds may be used in combination if necessary when applied to a heat-sensitive recording medium or the like. The color tone of these fluoran compounds varies depending on the substituent group that the fluoran compound has and the type of acidic substance used, but generally they form a yellow to red colored image.

In the present invention, the acidic substances constituting the heat-sensitive recording layer together with the above-mentioned specific fluoran compounds include known organic acidic substances such as aromatic carboxylic acid derivatives and phenol derivatives, and inorganic acidic substances such as acid clay. Acidic substances can be used. Specific examples of such acidic substances include the following. Benzoic acid, 4
-tert-butylbenzoic acid, 4-chlorobenzoic acid, 4
-Nitrobenzoic acid, phthalic acid, gallic acid, salicylic acid,
3-isopropylsalicylic acid, 3-phenylsalicylic acid, 3-cyclohexylsalicylic acid, 3,5-di-ter
t-Butylsalicylic acid, 3-methyl-5-benzylsalicylic acid, 4-pentyloxysalicylic acid, 4-(2-p
-Tolylsulfonylethoxy)salicylic acid, 4-(2-
Phenoxyethoxy) salicylic acid, 5-[p-(2-p
-methoxyphenoxyethoxy)cumyl]salicylic acid,
Aromatic carboxylic acid derivatives such as 3-phenyl-5-(α,α-dimethylbenzyl)salicylic acid, 3,5-di-(α-methylbenzyl)salicylic acid, 2-hydroxy-1-benzyl-3-naphthoic acid; 4,4'-isopropylidene diphenol (bisphenol A), 4,4'-isopropylidene bis(2-chlorophenol), 4,4'
-isopropylidene bis(2,6-dichlorophenol), 4,4'-isopropylidene bis(2,6-dibromophenol), 4,4'-isopropylidene bis(2,6-dibromophenol),
-methylphenol), 4,4'-isopropylidene bis(2,6-dimethylphenol), 4,4'-isopropylidene bis(2-tert-butylphenol),
4,4'-sec-butylidene diphenol, 2,2
'-bis(4-hydroxyphenyl)-4-methylpentane, 4,4'-cyclohexylidene bisphenol,
4,4'-cyclohexylidene bis(2-methylphenol), 4-tert-butylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, α-naphthol, β-naphthol, methyl-4-hydroxybenzoate, benzyl- 4-hydroxybenzoate,
2,2'-thiobis(4,6-dichlorophenol),
4-tert-octylcatechol, 2,2'-methylenebis(4-chlorophenol), 2,2'-methylenebis(4-methyl-6-tert-butylphenol)
, 2,2'-dihydroxydiphenyl, methyl-bis(4-hydroxyphenyl) acetate, ethyl-bis(4-hydroxyphenyl) acetate, benzyl-bis(4-hydroxyphenyl) acetate, 4,4'-
(p-phenylene diisopropylidene) diphenol,
4,4'-(m-phenylenediisopropylidene)diphenol, 4-hydroxydiphenylsulfone, 4,4
'-Dihydroxydiphenylsulfone, 4-hydroxy-4'-methyl-diphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxy-3',4'-tetramethylenediphenylsulfone, 2,2'- Phenolic compounds such as diallyl-4,4'-dihydroxydiphenylsulfone; p-phenylphenol-formalin resin, p-butylphenol-
Organic acidic substances such as phenolic resins such as acetylene resin; Furthermore, these organic acidic substances such as zinc, magnesium, aluminum, calcium, titanium, manganese,
Salts with polyvalent metals such as tin and nickel; metal complex compounds such as antipyrine complexes of zinc thiocyanate, etc. Of course, it is not limited to these, and it is also possible to use two or more types in combination as necessary.

[0022] In the heat-sensitive recording material of the present invention, there is no particular limitation on the ratio of the specific fluoran compound and the acidic substance used, but in general, the fluoran compound 1
0.1 to 50 parts by weight, preferably 1
Preferably, ~20 parts by weight of acidic material is used.

The present invention uses the above-mentioned specific fluoran compound as a dye precursor; however, if necessary, known dye precursors may be used in combination within a range that does not impede the desired effects of the present invention. You can also. Specific examples of such known dye precursors include the following. 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3,3-bis(p-dimethylaminophenyl)phthalide, 3-(4-dimethylaminophenyl)-3-(4-diethylamino -2-methylphenyl)-6-dimethylaminophthalide, 3-(p-dimethylaminophenyl)-3-(1,2-dimethylindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)- 3-(2-methylindol-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-ethylcarbazol-3-yl)-6-dimethylaminophthalide, 3,3-bis(2-phenylindol-3-yl)
-6-dimethylaminophthalide, 3-(p-dimethylaminophenyl)-3-(1-methylpyrrol-3-yl)-6-dimethylaminophthalide, 3-(p-dibenzylaminophenyl)-3 -(1,2-dimethylindol-3-yl)-7-azaphthalide, 3-(4-diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methylindol-3-yl)-7- Azapthalide, 3,3-bis(1-ethyl-2-methylindol-3-yl)phthalide, N-butyl-3-{bis[4-
Triarylmethane compounds such as (N-methylanilino)phenyl]methyl}carbazole, 4,4'-bis(
dimethylamino)benzhydrylbenzyl ether, N
-halophenyl-leucoauramine, N-2,4,5-
Diphenylmethane compounds such as trichlorophenyl leuko auramine, 4,4'-bis(dimethylamino)benzhydryl-p-toluenesulfinic acid ester, 3,
Thiazine compounds such as 7-bis(diethylamino)-10-benzoylphenoxazine, benzoylleucomethylene blue, p-nitrobenzoylleucomethylene blue, 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3-phenylspirodi Spiros such as naphthopyran, 3-benzylspirodinaphthopyran, 3-methylnaphtho(6'-methoxybenzo)spiropyran, 3-propylspirodibenzopyran, di-β-naphthospiropyran, 3-methyl-di-β-naphthospiropyran, etc. based compounds, rhodamine-B-anilinolactam, rhodamine (p-nitroanilino)lactam, rhodamine (
lactam compounds such as o-chloroanilino)lactam,
3-diethylamino-6-methylfluorane, 3-dimethylamino-7-methoxyfluorane, 3-diethylamino-6-methoxyfluorane, 3-diethylamino-
7-methoxyfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7
-chlorofluorane, 3-diethylamino-6,7-dimethylfluorane, 3-(N-ethyl-p-toluidino)-7-methylfluorane, 3-diethylamino-7-
(N-acetyl-N-methylamino)fluorane, 3-
Diethylamino-7-(N-methylamino)fluoran, 3-diethylamino-7-dibenzylaminofluoran, 3-diethylamino-7-(N-methyl-N-benzylamino)fluoran, 3-diethylamino-7-(
N-β-chloroethyl-N-methylamino)fluorane, 3-diethylamino-7-diethylaminofluorane, 4-benzylamino-8-diethylaminobenzo[a
] Fluoran, 3-[4-(4-dimethylaminoanilino)anilino]-7-chloro-6-methylfluoran,
8-[4-(4-dimethylaminoanilino)anilino]
Benzo[a]fluorane, 3-(N-ethyl-p-toluidino)-6-methyl-7-phenylaminofluorane, 3-(N-ethyl-p-toluidino)-6-methyl-
7-(p-toluidino)fluoran, 3-diethylamino-6-methyl-7-phenylaminofluoran, 3-
Dibutylamino-6-methyl-7-phenylaminofluorane, 3-dipentylamino-6-methyl-7-phenylaminofluorane, 3-diethylamino-7-(2
-carbomethoxy-phenylamino)fluorane, 3-
(N-ethyl-N-isoamylamino)-6-methyl-
7-phenylaminofluorane, 3-(N-cyclohexyl-N-methylamino)-6-methyl-7-phenylaminofluorane, 3-pyrrolidino-6-methyl-7-
Phenylaminofluorane, 3-piperidino-6-methyl-7-phenylaminofluorane, 3-diethylamino-6-methyl-7-xylidinofluorane, 3-diethylamino-7-(o-chlorophenylamino)fluorane, 3 -dibutylamino-7-(o-chlorophenylamino)fluorane, 3-(N-methyl-N-propylamino)-6-methyl-7-phenylaminofluorane, 3-pyrrolidino-6-methyl-7-p- Butylphenylaminofluoran, 3-(N-ethyl-N-isobutylamino)-6-methyl-7-phenylaminofluoran, 3-pyrrolidino-6-methyl-7-p-n-butylphenylaminofluoran, 3-(N-methyl-N-n
-hexylamino)-6-methyl-7-phenylaminofluorane, 3-(N-ethyl-N-n-hexylamino)-6-methyl-7-phenylaminofluorane, 3
-(N-ethyl-N-cyclopentylamino)-6-methyl-7-phenylaminofluorane, 3-[N-(3
-ethoxypropyl)-N-methylamino]-6-methyl-7-phenylaminofluorane, 3-[N-ethyl-N-(3-ethoxypropyl)amino]-6-methyl-7-phenylaminofluorane , 3-diethylamino-7-[m-(trifluoromethyl)phenylamino]
Fluoran, 3-diethylamino-7-(o-fluorophenylamino)fluoran, 3-dibutylamino-7
-(o-fluorophenylamino)fluorane, 3-diethylamino-6-chloro-7-phenylaminofluorane, 3-(N-ethyl-N-p-tolylamino)-7
-Methylfluorane, 3-(N-ethyl-N-tetrahydrofurfurylamino)-6-methyl-7-anilinofluorane, 3-(N-cyclopentyl-N-ethylamino)-6-methyl-7- Anilinofluorane, 3-(N
-ethyl-N-p-tolylamino)-6-methyl-7-
Anilinofluorane, 2,2'-bis{4-[6'-(
N-cyclohexyl-N-methylamino)-3'-methylspiro[phthalide-3,9'-xanthene]-2'-
Fluorane compounds such as ylamino]phenylpropane, 3,6-bis(dimethylamino)fluorene-9-
Spiro-3'-(6'-dimethylamino)phthalide, 3
-diethylamino-6-(N-allyl-N-methylaminofluorene-9-spiro-3'-(6'-dimethylamino)phthalide, 3,6-bis(dimethylamino)-spiro[fluorene-9,6'-6'H-chromeno (4,
3-b) indole], 3,6-bis(dimethylamino)-3'-methyl-spiro[fluorene-9,6'-6
'H-chromeno(4,3-b)indole], 3,6-
Fluorene compounds such as bis(diethylamino)-3'-methyl-spiro [fluorene-9,6'-6'H-chromeno(4,3-b)indole], and the like.

In the present invention, various thermofusible substances can also be used as recording sensitivity improvers in order to obtain higher speed recording performance. Examples of such thermofusible substances include caproic acid amide, capric acid amide, palmitic acid amide, stearic acid amide, oleic acid amide, erucic acid amide, linoleic acid amide, linolenic acid amide,
N-methylstearamide, stearanilide, N-methyloleic acid amide, benzanilide, linoleic acid anilide, N-ethylcapric acid amide, N-butyllauric acid amide, N-octadecyl acetamide, N-oleic acid amide, N- Oleylbenzamide, N-stearylcyclohexylamide, polyethylene glycol, 1-benzyloxynaphthalene, 2-benzyloxynaphthalene, 1-hydroxynaphthoic acid phenyl ester, 1,2-diphenoxyethane, 1,4
-diphenoxybutane, 1,2-bis(3-methylphenoxy)ethane, 1,2-bis(4-methoxyphenoxy)ethane, 1-phenoxy-2-(4-chlorophenoxy)ethane, 1-phenoxy-2 -(4-methoxyphenoxy)ethane, 1-(2-methylphenoxy)-2
-(4-Methoxyphenoxy)ethane, dibenzyl terephthalate, dibenzyl oxalate, di-p-methylbenzyl oxalate, benzyl p-benzyloxybenzoate, p-benzylbiphenyl, 1,5-bis (p-methoxyphenoxy)-3-oxa-pentane, 1,4-bis(2-vinyloxyethoxy)benzene, p-biphenyl p-tolyl ether,
Examples include compounds such as benzyl-p-methylthiophenyl ether.

[0025] Preparation of a coating liquid for a heat-sensitive recording layer containing these is as follows:
Generally, water is used as a dispersion medium, and ball mills, attritors,
It is prepared by dispersing the dye precursor and the acidic substance together or separately using a stirring/pulverizing machine such as a sand mill. Such coating liquids usually contain starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, styrene/maleic anhydride copolymer salt, styrene/acrylic acid copolymer salt,
Vinyl acetate/maleic anhydride copolymer salt, polyacrylate,
A styrene-butadiene copolymer emulsion or the like is blended in an amount of about 10 to 40% by weight, preferably about 15 to 30% by weight of the total solids.

Furthermore, various auxiliary agents can be added to the coating solution, such as dispersants such as sodium dioctyl sulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, fatty acid metal salts, etc. , triazole-based ultraviolet absorbers, other antifoaming agents, fluorescent dyes, colored dyes, and the like. Further, a dispersion or emulsion of stearic acid, polyethylene, carnauba wax, paraffin wax, zinc stearate, calcium stearate, ester wax, etc. may be added to prevent sticking from contact with a recording device or a recording head. In addition, kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide,
Inorganic pigments such as diatomaceous earth, particulate anhydrous silica, and activated clay may also be added. The amount of pigment added is generally adjusted within a range of about 0.1 to 10 parts by weight, preferably about 0.5 to 3 parts by weight, per 1 part by weight of the acidic substance. As the support, paper, plastic film, synthetic paper, etc. can be used, and paper is preferably used in terms of cost, coatability, etc. Further, the amount of the coating liquid forming the recording layer applied to the support is not particularly limited, and is usually 2 to 12 g/m2 in terms of dry weight.
, preferably within a range of about 3 to 10 g/m2. The method for applying the coating liquid for the recording layer is not particularly limited either, and the recording layer can be formed by appropriately selecting from known coating apparatuses.

Furthermore, on the recording layer, for the purpose of protecting the recording layer, 0.2 to 10 g/m2, preferably 0.5 to 3 g/m2,
Of course, it is also possible to provide an overcoat layer mainly composed of a water-soluble polymer or a water-dispersible polymer emulsion of about g/m2, or to provide an undercoat layer mainly composed of a pigment and a binder on the support. Various known techniques in the field of heat-sensitive recording material manufacturing can be added.

[0028]

[Examples] The present invention will be explained in more detail with reference to Examples below, but the present invention is of course not limited to these. In addition, unless otherwise specified, parts and % in the examples represent parts by weight and % by weight, respectively.

Example 1 3.3 g of fluorescein, 5.2 g of di-tert-butyl dicarbonate, and 1.9 g of pyridine were mixed and reacted at room temperature for 3 hours. After the reaction, the reaction mixture was extracted with ethyl acetate, washed with water, and then the solvent was distilled off. Then, it was recrystallized from ethanol to give colorless crystals with a melting point of 153 to 155.
4.8 g of 3,6-di(tert-butoxycarboxy)fluoran was obtained. The yield was 90%. This fluoran compound decomposed and developed a yellow color when melted, and although it was colorless when using silica gel without heating, it developed a yellow color when heated with a hair dryer.

Example 2 4.7 g of 3',4',5',6'-tetrachlorofluorescein, tert-butyl chloroformate 3.
3 g and 1.9 g of pyridine in 2-butanone.
The reaction was carried out at 0°C for 3 hours. After the reaction, the reaction mixture was extracted with ethyl acetate, washed with water, and then the solvent was distilled off. Then,
Recrystallization from ethanol yields colorless crystals of 3,6-di(te).
rt-butoxycarboxy)-3',4',5',6'
-5.6 g of tetrachlorofluorane was obtained. Yield is 83
%Met. This fluoran compound has 180 to 190
It decomposed at °C and developed an orange color, and although it was colorless on silica gel without heating, it developed an orange color when heated with a hair dryer.

Example 3 6.5 g of 2,4,5,7-tetrabromofluorescein
and 3.3 g of chloroformic acid-tert-butyl ester,
The reaction was carried out in pyridine at 70°C for 2 hours. After the reaction, the reaction mixture was extracted with ethyl acetate, washed with water, and then the solvent was distilled off. Then, it was recrystallized from ethanol to give 3,6-di(tert-butoxycarboxy)- as colorless crystals.
7.2 g of 2,4,5,7-tetrabromofluorane was obtained. The yield was 85%. This fluoran compound is
It decomposed at 178 to 191°C and developed an orange color, and although it was colorless on silica gel without heating, it developed an orange color when heated with a hair dryer.

Example 4 3-Hydroxy-6-dimethylaminofluorane 3.6
g and 3.3 g of chloroformic acid tert-butyl ester were reacted in pyridine at 60° C. for 3 hours. After the reaction,
The reaction mixture was extracted with ethyl acetate, washed with water, and then the solvent was distilled off. Then, it was recrystallized from ethanol to give 3-(tert-butoxycarboxy)-6 as pale pink crystals.
-3.9 g of dimethylaminofluorane was obtained. Yield is 8
It was 5%. This fluoran compound has 182 to 19
It decomposed at 1°C and developed a red color, and although it was pale pink on silica gel without heating, it developed a red color when heated with a hair dryer.

Example 5 3.9 g of 2,7-diethylfluorescein, 3.3 g of chloroformic acid tert-butyl ester and 1 pyridine.
．． 9 g were reacted in 2-butanone at 60° C. for 3 hours. After the reaction, the reaction mixture was extracted with ethyl acetate, washed with water, and then the solvent was distilled off. Next, recrystallize with ethanol,
4.4 g of colorless crystals of 3,6-di(tert-butoxycarboxy)-2,7-diethylfluorane were obtained. The yield was 75%. This fluoran compound is 185~
It decomposed at 196°C and developed a yellow color, and although it was colorless on silica gel without heating, it developed a yellow color when heated with a hair dryer.

Example 6 3.5 g of 3-hydroxy-6-methoxyfluorane, 2.6 g of di-tert-butyl dicarbonate, and 1.0 g of pyridine were mixed and reacted at 50° C. for 3 hours. After the reaction, the reaction mixture was extracted with ethyl acetate, washed with water, and then the solvent was distilled off. Then, it was recrystallized from ethanol to give 3-(tert-butoxycarboxy) as pale yellow crystals.
3.2 g of -6-methoxyfluorane was obtained. Yield is 72
%Met. This fluoran compound has 160 to 165
It decomposed at ℃ and developed a yellow color, and although it was pale yellow on silica gel without heating, it developed a yellow color when heated with a hair dryer.

Example 7 4.2 g of 4,5-dinitrofluorescein, 5.2 g of di-tert-butyl dicarbonate, and 1.9 g of pyridine.
were mixed and reacted at room temperature for 3 hours. After the reaction, the reaction mixture was extracted with ethyl acetate, washed with water, and then the solvent was distilled off. Then, it was recrystallized from ethanol to give 3,6-di(tert-butoxycarboxy)-4,5 as pale yellow crystals.
-4.3 g of dinitrofluorane were obtained. The yield was 70%. This fluoran compound decomposed at 182 to 193° C. and developed an orange color, and was pale yellow on silica gel without heating, but developed an orange color when heated with a hair dryer.

Example 8 4.3 g of 2-hexyl-8-methylfluorescein, 5.2 g of di-tert-butyl dicarbonate, and 1.9 g of pyridine were mixed and reacted at room temperature for 3 hours. After the reaction, the reaction mixture was extracted with ethyl acetate, washed with water, and then the solvent was distilled off. Then, it was recrystallized from ethanol to obtain 4.7 g of 3,6-di(tert-butoxycarboxy)-2-hexyl-8-methylfluorane as colorless crystals. The yield was 75%. This fluoran compound is
It decomposed at 185 to 195°C and developed a yellow color, and although it was colorless on silica gel without heating, it developed a yellow color when heated with a hair dryer.

Example 9 4.0 g of 3-hydroxy-6-piperidinofluorane,
2.6 g of di-tert-butyl dicarbonate and 1.0 g of pyridine were mixed and reacted at room temperature for 3 hours. After the reaction, the reaction mixture was extracted with ethyl acetate, washed with water, and then the solvent was distilled off. Then, it was recrystallized from ethanol to give 3-(tert-butoxycarboxy) as pale pink crystals.
4.3 g of -6-piperidinofluorane was obtained. Yield is 7
It was 3%. This fluoran compound has 179 to 18
It decomposed at 9°C and developed a red color, and although it was pale pink on silica gel without heating, it developed a red color when heated with a hair dryer.

Example 10 4.7 g of 3',4',5',6'-tetrachlorofluorescein, 5.3 g of chloroformic acid-1,1-diethylhexyl ester and 1.9 g of pyridine were dissolved in 2-butanone. The mixture was reacted at 60°C for 3 hours. After the reaction, the reaction mixture was extracted with ethyl acetate, washed with water, and then the solvent was distilled off. Next, it was recrystallized from ethanol to give colorless crystals of 3,6-
Di(1,1-diethyhexyloxycarboxy)-3'
,4',5',6'-tetrachlorofluorane 6.5g
I got it. The yield was 78%. This fluoran compound decomposes at 185 to 196°C and develops an orange color, and
It was colorless on silica gel without heating, but turned orange when heated with a hair dryer.

Example 11 1,8-dimethyl-3',4',5',6'-tetrachlorofluorescein 5.0g, dicarbonate-di-tert-
5.2 g of butyl and 1.9 g of pyridine were mixed and reacted at room temperature for 5 hours. After the reaction, the reaction mixture was extracted with ethyl acetate, washed with water, and then the solvent was distilled off. Then,
Recrystallization from ethanol gave colorless crystals of 3,6-di(tert-butoxycarboxy)-1,8-dimethyl-3',4',5',6'-tetrachlorofluorane 4.
．． 9g was obtained. The yield was 70%. This fluoran compound decomposes at 180 to 190°C and develops a yellow color.
In addition, it was colorless on silica gel without heating, but turned yellow when heated with a hair dryer.

Example 12 3.3 g of fluorescein, 3.6 g of chloroformic acid-1,1-dimethylpropyl ester and 1.9 g of pyridine were reacted in 2-butanone at 60° C. for 3 hours. After the reaction, the reaction mixture was extracted with ethyl acetate, washed with water, and then the solvent was distilled off. Next, recrystallization from ethanol yields 3,6-di(1,1-
4.8 g of dimethylpropoxycarboxy)fluorane was obtained. The yield was 85%. This fluoran compound decomposed and developed a yellow color when melted, and although it was colorless on silica gel without heating, it developed a yellow color when heated with a hair dryer.

Example 13 3.3 g of fluorescein, 3.9 g of chloroformic acid-1,1-dimethylbutyl ester and 1.9 g of pyridine,
The reaction was carried out in 2-butanone at 60°C for 3 hours. After the reaction, the reaction mixture was extracted with ethyl acetate, washed with water, and then the solvent was distilled off. Subsequently, it was recrystallized from ethanol to obtain 5.0 g of 3,6-di(1,1-dimethylbutoxycarboxy)fluoran as colorless crystals with a melting point of 156 to 158°C. The yield was 85%. This fluoran compound decomposed and developed a yellow color when melted, and although it was colorless on silica gel without heating, it developed a yellow color when heated with a hair dryer.

Example 14 ■ Preparation of liquid A 3,6-di(tert-butoxycarboxy)fluorane 10 parts 1
,2-bis(3-methylphenoxy)ethane
20 parts methylcellulose 5% aqueous solution
20
Part water

110 parts This composition was ground with a sand mill until the average particle size was 2 μm. ■ Preparation of B solution 3,5-di(α-methylbenzyl)salicylic acid
30 copies
Methyl cellulose 5% aqueous solution

60 parts water

110 parts This composition was ground with a sand mill until the average particle size was 2 μm. ■ Formation of recording layer 160 parts of liquid A, 200 parts of liquid B, silicon oxide pigment (oil absorption:
180 ml/100 g), 150 parts of a 20% oxidized starch aqueous solution, and 210 parts of water were mixed and stirred to obtain a recording layer coating liquid. The resulting coating liquid was coated onto a 50 g/m2 high-quality paper to give a dry weight of 6.0 g/m2 and dried to obtain a heat-sensitive recording paper.

Examples 15-20 Six types of thermal recording paper were prepared in the same manner as in Example 14, except that the following compounds were used instead of 3,6-di(tert-butoxycarboxy)fluoran in the preparation of Liquid A. I got it. Example 15: 3-(tert-butoxycarboxy)-
6-Methoxyfluorane Example 16: 3-(tert-butoxycarboxy)-
6-di(methyl)aminofluorane Example 17: 3,6-di(tert-butoxycarboxy)-2,4,5,7-tetrabromofluorane Example 18: 3,6-di(tert-butoxy) carboxy)−
1,8-dimethyl-3',4',5',6'-tetrachlorofluoran Example 19: 3,6-di(1,1-dimethylpropoxycarboxy)fluoran Example 20: 3,6-dimethyl (1,1-dimethylbutoxycarboxy)fluorane

Examples 21 to 23 In preparing liquid B, 3,5-di(α-methylbenzyl)
Three types of thermal recording paper were obtained in the same manner as in Example 14, except that the following compounds were used instead of salicylic acid. Example 21: 4,4'-isopropylidene diphenol Example 22: 4-(2-p-tolylsulfonylethoxy)salicylic acid Example 23: Zinc salt of 3,5-di(α-methylbenzyl)salicylic acid

Example 24 The same procedure was followed except that in the preparation of Solution A, 20 parts of 3,5-di(α-methylbenzyl)salicylic acid was used instead of 20 parts of 1,2-bis(3-methylphenoxy)ethane. A thermosensitive recording paper was obtained in the same manner as in Example 14.

Comparative Examples 1-2 Two types of thermal recording paper were prepared in the same manner as in Example 14, except that the following compounds were used instead of 3,6-di(tert-butoxycarboxy)fluoran in the preparation of Liquid A. I got it. Comparative example 1: 3,6-dimethoxyfluorane Comparative example 2: 3
,6-di(n-butoxycarboxy)fluorane

The whiteness of the 13 types of heat-sensitive recording paper thus obtained was measured using a Hunter whiteness meter, and the results were
It is listed in the table. Next, the thermal facsimile (Hitachi HIFA
The color density was measured using a Macbeth densitometer (Model RD-914, manufactured by Macbeth), and the results are shown in Table 1. In addition, in order to evaluate heat resistance and moisture resistance, heat-sensitive recording paper after recording was tested in an atmosphere of 60°C (heat resistance) and at 40°C, 90%
R. H. After being left in the atmosphere (humidity resistant) for 100 hours, the color density of the recorded images was again measured using a Macbeth densitometer, and the results are shown in Table 1. Furthermore, in order to evaluate chemical resistance, after recording, a vinyl chloride film was layered on the thermal recording paper and left in an atmosphere of 40°C for 100 hours.
After applying ethanol to the coloring surface (plasticizer resistance) and after applying ethanol to the coloring surface (ethanol resistance), the fogging state of the blank area and the fading state of the recorded image were visually evaluated, and the results are shown in Table 1. Described.

[0048]

[0049]

[Table 1]

[0050]

[Effects of the Invention] As is clear from the results in the table, the heat-sensitive recording material using the fluoran compound of the present invention has high whiteness;
It also has excellent heat resistance, moisture resistance, chemical resistance, and plasticity resistance.
Moreover, it was an excellent recording medium with good color development.

Claims (4)

[Claims] [Claim 1] A fluoran compound represented by the following general formula [Formula 1]. [Formula, R represents a C4-12 tertiary alkyl group, R1
~R11 is a hydrogen atom, a halogen atom, C1~
12 alkyl group, C1-12 alkoxyl group, hydroxyl group, nitro group, -N(R12)(R13), -O(C
O) OR14 or -O(CO) R15. However, R12 and R13 are each a hydrogen atom; a C1-12 alkyl group; a C4-12 cycloalkyl group; an aralkyl group that may be substituted with a halogen atom, a C1-6 alkyl group, or a C1-6 alkoxyl group. ; Represents an aryl group which may be substituted with a halogen atom, a C1-6 alkyl group, or a C1-6 alkoxyl group, but R
12 and R13 together with the adjacent nitrogen atom are pyrrolidino groups,
A piperidino group or a hexamethyleneimino group may also be formed. In addition, R14 is a C1-12 alkyl group; a benzyl group; a halogen atom, a C1-6 alkyl group, a C1-12 alkyl group;
It represents an aryl group which may be substituted with 1 to 6 alkoxyl groups, R15 is a C1 to 12 alkyl group; a benzyl group; a halogen atom, a C1 to 6 alkyl group, a C1 to 6 alkyl group;
-N (R16)(R17) is an aryl group optionally substituted with an alkoxyl group of 6 to 6. In addition, R1
6, R17 are each hydrogen atom; C1-12 alkyl group; C4-12 cycloalkyl group; halogen atom, C
1-6 alkyl group, aralkyl group optionally substituted with C1-6 alkoxyl group; halogen atom,
This represents an aryl group that may be substituted with a C1-6 alkyl group or a C1-6 alkoxyl group, and R16 and R17 may form a pyrrolidino group, piperidino group, or hexamethyleneimino group together with the adjacent nitrogen atom. . ] [Claim 2] In the general formula [Formula 1], R is ter
The fluoran compound according to claim 1, which is a t-butyl group. 3. A heat-sensitive recording material comprising, on a support, a heat-sensitive recording layer containing a colorless to light-colored dye precursor and an acidic substance capable of coloring upon contact with the dye precursor, wherein the dye precursor A heat-sensitive recording material containing at least one kind of fluoran compound represented by the above general formula [Chemical formula 1]. [Claim 4] In the general formula [Formula 1], R is tert-
The heat-sensitive recording material according to claim 3, which is a butyl group.