JPH041083A - Recording material - Google Patents

Abstract

PURPOSE:To enhance the stability of a developed color image, in a recording material utilizing the color development due to the contact of an electron donating leuco dye with an electron acceptive compound, by using a specific compound as the electron donating leuco dye. CONSTITUTION:In a recording material utilizing the color development due to the contact of an electron donating leuco dye with an electron acceptive compound, a compound represented by general formula (1) [wherein R1 - R4 are a hydrogen atom, an alkyl group or an aryl group, R5 - R9 are a hydrogen atom or a monovalent group, m and n are an integer of 1 - 4 and R10 is -XR11, -PO(OR12)2, -CR13R14R15 or -NR16R17 (wherein X is an oxygen atom or a sulfur atom and R11 - R17 are a hydrogen atom or a monovalent group)] is used a the electron donating leuco dye. This leuco dye is used together with various compounds such as a triphenylmethanephthalide type compound, a fluorane type compound, a spiropyrane type compound or a fluorene type compound to make it possible to assemble a recording material. At this time, the aforementioned leuco dye is desirably used in an amount of 30% or more from the aspect of the improvement in characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a recording material, and more particularly to a recording material with improved stability of colored images.

(Prior Art) Recording materials using electron-donating colorless dyes and electron-accepting compounds are already well known as pressure-sensitive paper, thermal paper, light-sensitive pressure-sensitive paper, electrically conductive thermal recording paper, thermal transfer paper, and the like. For example, British Patent No. 2140449, U.S. Patent No. 4480052, U.S. Pat.
For details, see No. 60-123557.

As a recording material, in recent years (1) color density and color sensitivity (2)
) Research is being carried out to improve properties such as before use and the fastness of colored images.

Among these, in particular, (2)
There is a strong demand for

For example, the blue light coloring agent 3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (i.e., crystal violet lactone) develops a deep blue color quickly, but the light resistance of the colored image is Plasticizer resistance is extremely poor. Alternatively, although the fastness of the colored image (light fastness, plasticizer resistance) is good, it has drawbacks such as low solubility in the encapsulation solvent, already colored blue by itself, and low coloring density.

The present inventors have determined that specific compounds are effective in improving these properties.

(Objective of the Invention) Therefore, an object of the present invention is to provide a recording material using a material which has good stability of a colored image and satisfies other requirements.

(Structure of the Invention) An object of the present invention is to provide a recording material that utilizes color development through contact between an electron-donating colorless dye and an electron-accepting compound, in which the electron-donating colorless dye is represented by the following general formula (1). This was achieved using a recording material characterized by the use of a compound that

Chunichi 1 to R4 in the above formula represent a hydrogen atom, an alkyl group, or an aryl group, R, -R, represent a hydrogen atom or a -valent group, m and n are 1
, R1 is -XR10-PO(OR10
), -CR10R10R10, -NFt, , R (x represents an oxygen atom or a sulfur atom, and R++ to R1 represent a hydrogen atom or a -valent group).

In particular, when R1, is -CR,,R,,Fl,, R1
It is preferable that at least one of 0, R4, and Rls is an electron-withdrawing group.

More preferably, R1-R1 is a hydrogen atom, an alkyl group,
Aryl group, R1-R7 is hydrogen atom, alkyl group, alkoxy group, alkylthio group, alkoxycarbonyl group, aryl group, aryloxy group, arylthio group, aryloxycarbonyl group, cyano group, R10R is hydrogen atom, alkyl group, aryl group, alkoxy group, aryloxy group, cyano group, nitro group, substituted amino group,
Hydroxy group, halogen atom, alkoxycarbonyl group, aryloxycarbonyl group, acyloxy group, m
, n is an integer from 1 to 4, R5, is -XR10-PO(
OR10),.

-CR, , R, , R, , -N represents R, , R.

In the above formula,
N = CR,,R,,,N R,,R,, [R
58, R7, is a hydrogen atom, alkyl group, aryl group, heterocyclic group, R10, R11% R11% R11 is a hydrogen atom, alkyl group, aryl group, heterocyclic group, COR10
, So, R10 (R10 and RII represent a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group)].

R7 represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. Furthermore, R1, may be linked to each other to form a 4- to 12-membered ring structure which may contain a hetero atom.

R18, R74, R+s are hydrogen atom, alkyl group, aryl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, halogen atom, cyano group, nitro group, So, R10, COR10, NR,,R,, (Fl, , Fl, represents a hydrogen atom, an alkyl group, an aryl group, a heterocyclic group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, a hydroxyl group,
R, , R, , R11% RII, R30, R1
1 is a hydrogen atom, an alkyl group, an aryl group, a heterocyclic group, S
o, R10, COR10 (R10, R10 are hydrogen atoms,
represents an alkyl group, aryl group, or heterocyclic group].

Furthermore, Rljs R11 may be linked to each other to form a 4- to 12-membered ring structure that may contain a heteroatom.

R11, R1, are hydrogen atoms, alkyl groups, aryl groups,
Heterocyclic group, So, R10, COR10, hydroxy group,
NR, , R, , [R8, RII is a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, a heterocyclic group, NR, , R, , R16, R11,
R, , R, is a hydrogen atom, an alkyl group, an aryl group,
Heterocyclic group, So, R10, COR10 (R10, R++
represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group]. Further, R71 and R++ may be linked to each other to form a 4- to 12-membered ring structure that may contain a hetero atom.

In addition, the alkyl group, aryl group, and heterocyclic group further include an alkyl group, an alkoxy group, a 7-aryl group, an aryloxy group,
It may have a substituent such as a halogen atom, a cyano group, a substituted carbamoyl group, a substituted sulfamoyl group, a substituted amine group, a substituted oxycarbonyl group, a substituted oxysulfonyl group, an alkylthio group, or an arylsulfonyl group.

More specifically, among the substituents represented by R7-R4, hydrogen atoms, alkyl groups having 1 to 18 carbon atoms, 6 to 1
The aryl group of 2 is preferred.

R1-R4 are hydrogen atoms, methyl groups, ethyl groups, n
-propyl group, 1so-propyl group, n-butyl group, 1
so-butyl group, n-amyl group, is.

-Amyl group, n-hexyl group, n-hebutyl group, n-octyl group, 2-ethylhexyl group, n-dodecyl group, n
-Octadecyl group, β-methoxyethyl group, β-ethoxyethyl group, γ-methoxypropyl group, γ-ethoxypropyl group, β-phenoxyethyl group, β-cyanoethyl group, β-chloroOethyl group, β-hydroxy Ethyl group, cyclopentyl group, cyclohexyl group, tetrahydrofurfuryl group, phenyl group, tolyl group, cyclophenyl group,
Examples include methoxyphenyl group, benzyl group, phenethyl group, methylbenzyl group, chlorobenzyl group, and methoxybenzyl group.

It is preferable that R1 and R1 are not hydrogen atoms at the same time.

R1, R10R, and R4 are bonded to each other to form a ring which may contain a 5- to 8-membered heteroatom including the nitrogen atom to which they are bonded, such as pyrrolidine, piperidine, morpholine, thiomorpholine, A piperazine or caprolactam ring may be formed, and a benzene ring may also be included to form an indoline or julolidine ring.

Among the substituents represented by R, -R, hydrogen atoms, alkyl groups having 1 to 18 carbon atoms, alkoxy groups, alkylthio groups, alkoxycarbonyl groups, and 6 to 1 carbon atoms;
2, 7-aryl group, aryloxy group, arylthio group,
An aryloxycarbonyl group or a cyano group is preferred.

More specifically about R, -R, hydrogen atom, methyl group,
Ethyl group, propyl group, butyl group, amyl group, hexyl group, octyl group, octadecyl group, methoxypropyl group, ethoxypropyl group, phenoxyethyl group, cyclopentyl group, cyclohexyl group, allyl group, benzyl group,
Phenethyl group, phenyl group, 4-methylphenyl group, 3
-Methylphenyl group, 2-methylphenyl group, 4-methoxyphenyl group, 3-methoxyphenyl group, 2-methoxyphenyl group, 4-N,N-dimethylaminophenyl group, 3-N,N-dimethylaminophenyl group ,2-N,N
-dimethylaminophenyl group, cyano group, methoxycarbonyl group, ethoxycarbonyl group, and methylthio group.

Furthermore, R1 to R, may be linked to each other and to adjacent aryl groups or heterocyclic groups to form a cyclic 4- to 12-membered ring structure that may contain a petro atom, particularly 5- to 8-membered ring structures. It is preferable to form a membered ring structure. Furthermore, this ring may have a substituent such as an alkyl group, an alkoxy group, or a 7-aryl group.

In particular, it is preferable that R, -R, each be a hydrogen atom from the viewpoint of synthetic handling.

Among the substituents represented by Ft, Fl, hydrogen atom, alkyl group having 1 to 12 carbon atoms, alkoxy group, alkoxycarbonyl group having 2 to 12 carbon atoms, 7-syloxycarbonyl group, 6 carbon atoms 12 7-aryl groups, aryloxy groups, 7-12 carbon atoms 7-aryloxycarbonyl groups, hydroxy groups, chlorine atoms, bromine atoms, fluorine atoms, nitro groups, cyano groups, amino groups, 1 to 1 carbon atoms A mono- or difulkylamino group having 12 carbon atoms, a mono- or diaryl 7-mino group having 6 to 12 carbon atoms, and a 7-syl amino group having 1 to 12 carbon atoms are preferred.

Ft,,R, is hydrogen atom, methyl group, ethyl group,
Propyl group, butyl group, octyl group, phenyl group, tolyl group, benzyl group, phenethyl group, methoxy group, ethoxy group, propoxy group, butoxy group, octyloxy group,
Examples include benzyloxy group, phenoxyethoxy group, phenoxy group, chlorine atom, bromine atom, fluorine atom, nitro group, cyano group, dimethylamino group, diethylamino group, acetylamino group, acetyloxy group, and methoxycarbonyl group.

R10R, is −NR, PI, , −NR from the point of view of coloring wavelength.
, R, is preferably in the meta position.

Among the substituents represented by R1, those having 20 or less carbon atoms are preferred.

Furthermore, R1# is -XR10 in terms of synthetic handling.
, -CR10Fl, , R10, -N R, , R are preferred.

In particular, from the viewpoint of stability of the leuco color former when used in recording materials, -CR, , R, , R, are preferred.

R1# includes methoxy group, ethoxy group, propoxy group, butoxy group, Schiff O hexyloxy group, octyloxy group, dodecyloxy group, octadecyloxy group, benzyloxy group, phenethyloxy group, phenylbutyloxy group, 4 -Methylbenzyloxy group, 4-chlorobenzyloxy group, 4-methoxybenzyloxy group, β-
Phenoxyethoxy group, β-(4-methylphenoxy)
Ethoxy group, β-(3-methylphenoxy)ethoxy group, β-(2-methylphenoxy)ethoxy group, β-(4
-methoxyphenoxy)ethoxy group, β-phenylthioethoxy group, β-phenylsulfonylethoxy group, β-
Naphthyloxyethoxy group, phenoxyethoxyethoxy group, pyridylmethoxy group, phenoxy group, naphthyloxy group, 4-chlorophenoxy group, 4-methylphenoxy group, 3-methylphenoxy group, 2-methylphenoxy group, 4-ethylphenoxy group , 2,4-dichlorophenoxy group, methyliminooxy group, dimethyliminooxy group, phenyliminooxy group, diethylphosphonyl group,
dibutylphosphonyl group, diphenylphosphonyl group, di(
4-tolyl)phosphonyl group, di(4-chlorophenyl)
Phosphonyl group, di(4-methoxyphenyl)phosphonyl group, di(4-nitrophenyl)phosphonyl group, di(4-
cyanophenyl)phosphonyl group, di(naphthalene-1-
yl)phosphonyl group, di(naphthalen-2-yl)phosphonyl group, di(2,4-dichlorophenyl)phosphonyl group, di(4-riro-3-methylphenyl)phosphonyl group, anilino group, 2-ri00anilino group , 2-methoxycarbonylanilino group, 2-nitroanilino group, 2-methoxyanilino group, 3-ethyl7nylino group, 4-fluoroanilino group, 4-butoxyanilino group, 2,4-dichloroanilino group , 2.5-dimethylanilino group, β-naphthylamino group, N-methylanilino group, N-butylanilino group, N-acetylanilino group, pyridylamino group, quinolyl amino group, cyclohexylamino group, indol-1-yl group , carbazol-1-yl group, succinylimide group, phthalimide group, acetylamino group, benzoylamino group, 2-methylbenzoylamino group, 4
- methylbenzoylamino group, 4-chlorobenzoylamino group, phenylsulfonylamino group, 4-methylphenylsulfonylamino group, 4-chlorophenylsulfonylamino group, pyrrolidino group, piperidino group, morpholino group, piperazino group, phenylhydrazino group, N-hydroxy-N-phenylsulfonylamino group, N-hydroxy-N-4-chlorophenylsulfonylamino group, benzoylhydrazino group, phenylsulfonylhydrazino group, benzoyloxy group, acetyloxy group, methylthio group, ethylthio group, phenylthio group , tolylthio group, benzylthio group, naphthylthio group, benzothiazole-2
-ylthio group, benzimidazol-2-ylthio group,
Benzoxazol-2-ylthio group, 1.1-diacetylmethyl group, 1,1-dicyanomethyl group, 1-acetyl-1-benzoylmethyl group, 1.1-dimethoxycarbonylmethyl group, 1.1-jethoxycarbonyl group Methyl group, 1゜1-diphenyloxycarbonylmethyl group, 1
゜1-di-n-butoxycarbonylmethyl group, 1゜1-
Di-t-butoxycarbonylmethyl group, 1゜1-dibenzyloxycarbonylmethyl group, 1゜1-dioctyloxycarbonylmethyl group, 1-7 cetyl-1-methoxycarbonylmethyl group, 1-7 cetyl-1-ethoxycarbonylmethyl group group, 1-acetyl-1-iso-propoxycarbonylmethyl group, 1-7cetyl-1-butoxycarbonylmethyl group, 1-7cetyl-1-hexyloxycarbonylmethyl group, 1-acetyl-1-octyloxycarbonylmethyl group , 1-7 cetyl-1-benzyloxycarbonylmethyl group, 1-7 cetyl-1-phenoxycarbonylmethyl group, 1-propionyl-1-methoxycarbonylmethyl group, 1-acetyl-1-ethoxycarbonylethyl group, 1.1- Diacetylethyl group, 1-
Pivaloyl-1-methoxycarbonylmethyl group, 1-cyano-1-ethoxycarbonylmethyl group, 1-benzoyl-1-ethoxycarbonylmethyl group, 1-7cetyl-1-morpholinocarbonylmethyl group, 1-methoxycarbonyl-1-ethoxy carbonylmethyl group, 1.1-diphenylsulfonylmethyl group, 1-tolylsulfonyl-
1-benzoylmethyl group, 1.1-di(trifluoromethylcarbonyl)methyl group, 1.1-dipivaloylmethyl group, 1-furoyl-1-trifluoromethylcarbonylmethyl group, 1-thienylcarbonyl-1 -trifluoromethylcarbonylmethyl group, 1.1-dicarbamoylmethyl group, 1-7cetyl-1-phenylcarbamoylmethyl group, 1.1-dibenzoylmethyl group, 1.1-dimethoxycarbonylethyl group, 1.1- Jetoxycarbonylethyl group, 1.1-diphenyloxycarbonylethyl group, 1,1-di-n-butoxycarbonylethyl group, 1.1-di-t-butoxycarbonylethyl group, 1.
1-dibenzyloxycarbonylethyl group, 1.1-simethoxycarbonyl-n-propyl group, 1゜1-dimethoxycarbonyl-n-butyl group, α.

α-dimethoxycarbonylbenzyl group, 1.1-simethoxycarbonyl-1-methoxymethyl group, 1.1-jethoxycarbonyl-n-propyl group, 1.1-jethoxycarbonyl-1so-propyl group, 1,1 -jethoxycarbonyl-n-butyl group, 1,1-jethoxycarbonyl-1so-butyl group, 1,1-jethoxycarbonyl-tert-butyl group, α, α-jethoxycarbonylbenzyl group, β, β- Jetoxycarbonylphenethyl group, 1.1-jethoxycarbonyl-1-allylmethyl group, 1.1-jethoxycarbonyl-1-7cetaminomethyl group, 1.1-jethoxycarbonyl-1-chloromethyl group, 1 .1-jethoxycarbonyl-1-cyclopentylmethyl group, 1.1-jethoxycarbonyl-1-phthalimidomethyl group, 1,1-jethoxycarbonyl-2-ethoxycarbonylethyl group, 1,1,1
．． -triethoxycarbonylmethyl group, benzoylmethyl group, 4-chlorobenzoylmethyl group, 4-nitrobenzoylmethyl group, 1-chloro-1-acetylmethyl group,
1-chloro-1-methoxycarbonylmethyl group, 1-bromo-1-benzoylmethyl group, nitromethyl group, 1-
Examples include nitroethyl group.

Next, specific examples of the color former of the present invention will be shown, but the present invention is not limited thereto.

In addition, these colorless dyes include well-known triphenylmethane phthalide compounds, fluoran compounds,
Fetch 7 Recorded in combination with various compounds such as zine compounds, indolylphthalide compounds, leucoauramine compounds, rhodamine lactam compounds, triphenylmethane compounds, triazene compounds, spiropyran compounds, and fluorene compounds. You can also assemble materials.

In this case, it is preferable to use the above-mentioned colorless dye in an amount of 30% or more from the viewpoint of improving properties.

Regarding these, for example, specific examples of phthalides are U.S. Reissue Patent No. 23.024 and U.S. Patent No. 3゜491.111.
No. 3,491,112, No. 3,491,116, and No. 3,509,174; specific examples of fluorans are U.S. Pat. Nos. 3,624.107 and 3,627,78.
No. 7, No. 3゜641.011, No. 3,462,828
No. 3,681,390, No. 3,920,510, No. 3,959,571, specific examples of spirodipyrans are U.S. Pat. No. 3,971,808, and pyridine and pyrazine compounds are U.S. Pat. Specific examples of fluorene compounds are described in Japanese Patent No. 3,775.424, Japanese Patent No. 3,853,869, Japanese Patent No. 4゜246.318, and Japanese Patent Application No. 61-240989.

Examples of electron-accepting compounds that impart color upon contact with colorless dyes include common compounds such as phenol derivatives, salicylic acid derivatives, metal salts of aromatic carboxylic acids, acid clay, bentonite, novolac resins, metal-treated novolac resins, and metal complexes. are used, and these may be used in combination. Examples of these are Tokuko No. 9309, No. 40-9309, and Tokuko No. 4
5-14039, JP 52-140483, JP 48-51510, JP 57-210886,
JP-A-58-87089, JP-A-59-11286, JP-A-60-176795, JP-A-61-9598
No. 8, U.S. Patent No. 3,767°449, U.S. Patent No. 4,219,
No. 219, No. 4.269.893, No. 4,374,6
No. 71, No. 4゜687.869, etc.

Especially salicylic acid derivatives, phenol derivatives, metal complexes,
A combination with acid clay and bentonite is preferred. When these are applied to recording materials, they are used in the form of fine dispersions or fine droplets, or in the form of films.

Furthermore, in this case, various additives well known in the fields of recording materials and polymer resins, Dasaba pigments, waxes, antistatic agents, ultraviolet absorbers, antifoaming agents, conductive agents, and fluorescent agents are used. Additives such as dyes and surfactants are used.

For use with pressure sensitive paper, U.S. Patent 2,505°470
No. 2,505,471, No. 2,505.489, No. 2,548,366, No. 2゜712.507,
2,730,456, 2,730,457, 3,103,404, 3,418,250, 4
It may take a variety of forms, as described in prior patents such as No. 010,038. It most commonly consists of at least one pair of sheets containing separately an electron-donating colorless dye and an electron-accepting compound.

A method of manufacturing capsules is described in U.S. Pat. No. 2.800.
457, a method using coacervation of a hydrophilic colloid sol described in British Patent Nos. 2,800,458, British Patent No. 867.797, British Patent No. 950,443, British Patent No. 98
There are interfacial polymerization methods described in US Pat. No. 9,264 and US Pat. No. 1.091.076, and the method described in US Pat.

The capsule wall material is preferably a synthetic resin-based wall material, for example, a polyurethane and/or polyurea-based material, or a melamine resin-based material.

In general, electron-donating colorless dyes are used alone or in combination as solvents (alkylated naphthalene, alkylated diphenyl, alkylated diphenylmethane, alkylated terphenyl, alkylated terphenyl, etc.).
Synthetic oils such as chlorinated paraffin, vegetable oils such as cotton oil and castor oil, animal oils, mineral oils, or mixtures thereof) are dissolved in microcapsules to produce paper, high-quality paper, plastic sheets, resin coatings, etc. A coloring agent sheet is obtained by applying it to ted paper, etc.

In addition to the electron-donating colorless dye, ultraviolet absorbers, antioxidants, and the like may be added as additives to the microcapsules. In particular, from the viewpoint of improving the stability of the electron-donating colorless dye in the capsule before use and the coloring of the capsule, benzotriazole-based ultraviolet absorbers, hindered amine-based antioxidants, hindered phenol-based antioxidants,
It is preferable to add an aniline antioxidant, a quinoline antioxidant, or the like.

In addition, an electron-accepting compound and optionally additives may be dispersed in a binder such as styrene-butadiene latex or polyvinyl alcohol, and used together with the pigment described below to produce paper, plastic sheets, resin-coated paper, etc. A developer sheet is obtained by coating the support.

The amounts of the electron-donating colorless dye and the electron-accepting compound to be used depend on the desired coating thickness, the form of the pressure-sensitive recording paper, the capsule manufacturing method, and other conditions, and may be appropriately selected depending on the conditions. It is easy for one skilled in the art to determine this amount to use.

When used for thermal paper, JP-A-62-144゜989
No. 62-244,883, etc. Specifically, the electron-donating colorless dye and the electron-accepting compound are 10μ or less in the dispersion medium,
It is preferably used after being pulverized and dispersed to a particle size of 3 μm or less. As the dispersion medium, an aqueous polymer solution having a concentration of about 0.5 to 10% is generally used, and dispersion is carried out using a ball mill, sand mill, horizontal sand mill, attritor, colloidal 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. At that time, it is preferable to use a thermofusible substance in combination. These are used in finely dispersed form at the same time as the electron-donating colorless dye or simultaneously with the electron-accepting compound. These are added at a weight ratio of 20% or more and 300% or less, particularly preferably 40% or more and 150% or less, based on the electron-accepting compound.

Additives may be added to the thus obtained coating liquid as necessary to meet various requirements. Examples of additives include dispersing oil-absorbing substances such as inorganic pigments and polyurea fillers in the binder in order to prevent the recording head from becoming dirty during recording, and also to improve releasability from the head. For this reason, fatty acids, metal soaps, etc. are added. Therefore, in addition to electron-donating colorless dyes and electron-accepting compounds that directly contribute to color development, thermofusible substances, pigments, waxes, antistatic agents, ultraviolet absorbers,
Additives such as antifoaming agents, conductive agents, fluorescent dyes, and surfactants are coated onto the support to form the recording material.

Furthermore, a protective layer may be provided on the surface of the heat-sensitive recording layer, if necessary. Two or more protective layers may be laminated as necessary. Further, a coating liquid similar to that of a protective layer may be applied to the back surface in order to correct the curl balance of the support or to improve chemical resistance from the back surface. An adhesive may be applied to the back side and a release paper may be further added to form a label.

Usually, the electron-donating colorless dye and the electron-accepting compound are dispersed in a binder and applied. Water-soluble binders are generally used, such as polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, shrimp chlorohydrin-modified polyamide, and ethylene-
Examples include maleic anhydride copolymer, styrene-maleic anhydride copolymer, inbutylene-maleic anhydride copolymer, polyacrylic acid, polyacrylic acid amide, methylol-modified polyacrylamide, starch derivatives, casein, gelatin, etc. . Further, for the purpose of imparting water resistance to these binders, a water resistance agent may be added, or an emulsion of a hydrophobic polymer, specifically, styrene-butadiene rubber latex, acrylic resin emulsion, etc. may be added. The coating liquid is applied onto base paper, wood-free paper, synthetic paper, plastic sheet, resin-coated paper, or neutral paper.

Examples of thermofusible substances are disclosed in JP-A-58-57989 and JP-A-58-87094. Examples of such compounds include 2-benzyloxynaphthalene, 4-
Benzyl biphenyl, 1゜2-di-m-tolyloxyethane, 1,2-diphenoxyethane, 1,4-diphenoxybutane, bis-[β-(p-methoxyphenoxy)
ethyl]ether, 1-phenoxy-2-p-ethylphenoxyethane, 1-p-methoxyphenoxy-2-phenoxypropane, 1-phenoxy-2-p-methoxyphenoxypropane, 1,2-bis(p-methoxyphenoxy ) Propane, 1,3-bis(p-methoxyphenoxy)propane, 1-p-methoxyphenoxy-2-〇-chlorophenoxyethane, 4-(p-methoxybenzylthio)anisole, 1-phenoxy-2-p- Methoxyphenylthioethane, 1,2-bis(p-methoxyphenylthio)ethane, 1-p-methylphenoxy-2-
Ether compounds such as p-methoxyphenylthioethane, 4-(4-chlorobenzyloxy)ethoxybenzene, stearic acid amide, methylene bisstearamide,
Examples include stearic acid anilide, behenic acid amide, stearic acid anilide, and stearyl urea.

Pigments include kaolin, calcined kaolin, talc, diatomaceous earth, calcium carbonate, aluminum hydroxide, magnesium hydroxide, zinc oxide, lithopone, amorphous silica, colloidal silica, calcined gypsum, silica, magnesium carbonate, titanium oxide, Alumina, barium carbonate, barium sulfate, mica, microballoons, urea-formalin fillers, polyester particles, cellulose fillers, etc. are used.

Examples of metal soaps include polyvalent metal salts of higher fatty acids, such as zinc stearate, aluminum stearate, calcium stearate, and zinc oleate.

Examples of waxes include paraffin wax, carboxy-modified paraffin wax, carnauba wax, microcrystalline wax, polyethylene wax, polystyrene wax, higher fatty acid esters, amides, and the like.

As the hindered phenol compound, a phenol derivative in which at least one of the 2nd and 6th positions is substituted with a branched alkyl group is preferred. For example, 1,1,3-tris(2-methyl-4-hydroxy-5-1-butylphenyl)butane, 1°1,3-tris(2-ethyl-4-
Hydroxy 5-t-butylphenyl)butane, 1,1.
3-tris(3,5-di-t-butyl-4-hydroxyphenyl)butane, 1,1.3-tris(2-methyl-
4-hydroxy-5-t-butylphenyl)propane,
4,4-butylidenebis(6-t-butyl-3-methylphenol, 4,4-thiobis(3-methyl-6-1-
butylphenol), 2,2-methylenebis(6-1-
butyl-4-methylphenol), 2,2-methylenebis(6-t-butyl-4-ethylphenol), octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, +, 3.5-trimethyl-2.4.6-tris(3,5-di-t-butyl-4-
hydroxybenzyl)benzene, tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propinate comethane, 2,2,6,6-tetramethyl-4-piperidinyl sebacate etc. can be mentioned.

The amount of the hindered phenol compound to be used is preferably 1 to 200% by weight, more preferably 5 to 100% by weight, based on the electron accepting compound.

As ultraviolet absorbers, cinnamic acid derivatives, benzophenone derivatives, benzotriazolylphenol derivatives, etc.
For example, butyl α-cyano-β-phenylcinnamate, 0
-benzotriazolylphenol, 0-benzotriazolyl-p-chlorophenol, 0-benzotriazolyl-p-methylphenol, 0-benzotriazolyl-2
, 4-di-t-butylphenol, 0-benzotriazolyl-2,4-di-t-octylphenol, and the like.

Water-resistant agents include water-soluble initial materials such as N-methylol urea, N-methylol melamine, and urea-formalin;
Examples include blend heat treatment of dialdehyde compounds such as glyoxal and glutaraldehyde, inorganic crosslinking agents such as boric acid and borax, polyacrylic acid, methyl vinyl ether-maleic acid copolymer, isobutylene-maleic anhydride copolymer, etc. .

Materials used for the protective layer include polyvinyl alcohol,
Carboxy-modified polyvinyl alcohol, vinyl acetate-acrylamide copolymer, silicon-modified polyvinyl alcohol, starch, modified starch, methylcellulose, carboxymethylcellulose, hydroxymethylcellulose, gelatins, gum arabic, casein, styrene-maleic acid copolymer hydrolyzate, Water-soluble polymers such as styrene-maleic acid copolymer half ester hydrolyzate, isobutylene-maleic anhydride copolymer hydrolyzate, polyacrylamide derivatives, polyvinylpyrrolidone, sodium polystyrene sulfonate, sodium alginate, and styrene-butadiene. Water-insoluble polymers such as rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, and vinyl acetate emulsion are used.

In addition, pigments, metal soaps, waxes, waterproofing agents, etc. may be added to the protective layer for the purpose of improving matching properties with the thermal head.

Further, when coating the protective layer on the thermosensitive coloring layer, a surfactant may be added in order to obtain a uniform protective layer. As the surfactant, a sulfosuccinic acid-based alkali metal salt, a fluorine-containing surfactant, etc. are used. Specifically, G (
Preferred are sodium salts or ammonium salts such as n-ethyl)sulfosuccinic acid and di(2-ethyl)sulfosuccinic acid, but anionic surfactants are effective.

The electrically conductive thermal paper is manufactured by the method described in, for example, Japanese Patent Application Laid-open No. 49-11344 and Japanese Patent Application Laid-Open No. 50-48930. Generally, a coating liquid in which a conductive substance, an electron-donating colorless dye, and an electron-accepting compound are dispersed together with a binder is applied to a support such as paper, or a conductive substance is applied to the support to form a conductive layer, and then a conductive layer is formed on the support. Thermal paper is manufactured by applying a coating liquid in which an electron-donating colorless dye, an electron-accepting compound, and a binder are dispersed. Note that the sensitivity can also be improved by using the thermofusible substance described above in combination.

The photosensitive pressure sensitive paper is manufactured by the method described in, for example, Japanese Patent Application Laid-open No. 179836/1983. In general, photopolymerization initiators such as silver bromide, silver bromide, silver behenate, Michler's ketone, benzoin derivatives, and benzophenone derivatives, and crosslinking agents such as polyfunctional monomers such as polyallyl compounds, poly(meth)acrylates, and poly(meth)acrylamides is encapsulated in a synthetic resin capsule such as polyether urethane or polyurea together with an electron-donating colorless dye and, if necessary, a solvent. After imagewise exposure, the unexposed area is colored by contacting with an electron-accepting compound using an electron-donating colorless dye.

The electron-donating colorless dye according to the present invention has the following general formula (1
1), (II+) as a raw material, known methods such as British Patent No. 2,101,648, Japanese Patent Publication No. 60-679
No. 4, JP-A-48-729, JP-A-63-20855
8. It can be easily obtained by referring to the method disclosed in JP-A No. 60-231766.

In the above formula, R+ -R+, m, and n have the above-mentioned meanings, and Y represents an anion necessary to form a dye, such as CI
, Br , Cl○, , PF.

Examples include BF, etc.

(Synthesis example 1) Compound of specific example (1) 4-N in a three-bottle flask with a stirrer.

N-dimethylaminobenzaldehyde 0.15nol,
4-N,N-dimethylaminoacetophenone 0.45n
ol, 28% sodium methoxide methanol solution 0
．． Weigh out 0.5nol and 200d of ethanol, and stir for 10 hours while refluxing.

After cooling, the precipitated crystals were filtered, washed with methanol, and 1-
(4-N,N-dimethylaminohendiyl)2- <4
-N,N-dimethylaminophenyl)ethylene 0.13
Obtained mol. Next, 0.15nol of lithium aluminum hydride, 500m of tetrahydrofuran (!
Weigh out the ketone mentioned above while stirring at room temperature.
Gradually add 1 mol and stir at room temperature for an additional hour. After cooling the reaction mixture and dropping 120 g of water, 7
A mixed solution of 0.1 m01 of 0% perchloric acid and 200 ml of acetic acid was then gradually added to 11 ml of water, and the precipitated crystals were filtered and washed with water to obtain the following compound (1) 104-. This compound 0. Olmol, methanol 5Od
0.011 mol of 28% sodium methoxide methanol solution was added dropwise while stirring, and the mixture was further stirred at room temperature for 1 hour. The reaction mixture was poured into water, filtered, and dried to produce pale yellow crystals (melting point 63-65).
°C).

(Synthesis Example 2) Compound of Example (9) Weighed 0.011 mol of sodium hydride and 40 d of tetrahydrofuran into a three-necked flask equipped with a stirrer, and after stirring, added 0.0105 mol of acetylacetone.
Add mol. After stirring at room temperature for 5 minutes, compound (IV) 0. 01 mol was gradually added and further stirred at 50°C for 1 hour. The reaction mixture is poured into water, filtered, and dried to obtain the desired product as pale yellow crystals (melting point 102~
4°C).

(Synthesis Example 3) Compound of Specific Example (19) Into a three-necked flask equipped with a stirrer, measure out 0.011 mol of sodium hydride and 40 d of tetrahydrofuran, and add 0.0+05 mol of piperidine while stirring.
drip. After stirring for 5 minutes at room temperature, compound (IV
) O,Ol mol was gradually added by lightning, and further 5 mol of O,Ol was added at room temperature.
Stir the time. The reaction mixture was soaked in water, filtered, and dried to obtain the desired product as pale yellow crystals (melting point 88-90°C).

(Synthesis Example 4) The following compound (
0.01 mol of V), 0.01 mol of dimethyl malonate. 01 m
ol.

Weigh out Ethyl Celsolve 30d and stir at 100°C for 3 hours. The reaction mixture was washed with water, filtered, and dried to obtain the desired product as pale yellow crystals (melting point: 116-8°C).

(Synthesis Example 5) Compound of Example (31) Weighed 0.01 mol of sodium hydride and 40 d of tetrahydrofuran into a three-necked flask equipped with a stirrer, and after stirring, added 0.01 mol of ethyl acetoacetate.
drip. After stirring for 5 minutes at room temperature, compound (IV
) 0. 01 mol was gradually added and further stirred at room temperature for 1 hour. The reaction mixture was poured into water, filtered, and dried to obtain the desired product as pale yellow crystals (melting point: 81-3°C).

(Examples of the Invention) Examples are shown below, but the present invention is not limited thereto. % represents weight % unless otherwise specified.

(Example 1) The compound of specific example (9), bisphenol A which is an electron accepting compound, and 4-(4-chlorobenzyloxy)ethoxybenzene which is a thermofusible substance, each 209 to 1009
They were dispersed with a 5% aqueous solution of polyvinyl alcohol (Clara PVA105) in a ball mill for one day and night to have a volume average particle size of 1.5 μm or less to obtain each dispersion. In addition, calcium carbonate 809 is added to 0.5 of sodium hexametaphosphate.
% solution of 1609% using a homogenizer to obtain a pigment dispersion.

The dispersions prepared as described above are mixed in a ratio of 59 electron-donating colorless dye dispersions, 109 electron-accepting compound dispersions, 109 thermofusible substance dispersions, and 159 pigment dispersions,
Furthermore, emulsion 39 of 21% zinc stearate was added to obtain a heat-sensitive coating liquid.

This coating liquid was applied to high-quality paper using a coating bar so that the dry weight of the coating layer was 5 g/m', and the temperature was 50°C.
After drying for 1 minute, a super calender was applied to obtain thermal recording paper.

The obtained thermal recording paper had no fog during raw storage and had excellent stability over time.

Thermal recording paper was heated using a thermal head manufactured by Kyocera Corporation (KLT-
216-8MPD1) and 100kg/just before the head.
When printing was carried out with a pulse width of 1.0 while using a pressure roll under conditions of a head voltage of 24 V and a pulse cycle of 10 ms in a thermal printing experimental apparatus having a CJ pressure roll, a blue image was obtained. Moreover, the obtained colored image showed good resistance to chemicals, sunlight, etc.

(Examples 2 to 3) In place of the electron-donating colorless dye and electron-accepting compound of Example 1, the following were used, respectively. A coated paper was obtained in the same manner as in Example 1 in other respects.

Example 2 Electron-donating colorless dye: Compound 109 of specific example (22),
Crystal violet lactone 109 Electron-accepting compound: bis(4-hydroxyphenyl) sulfone 59, benzimidazole complex of rhodan zinc 159 Example 3 Electron-donating colorless dye: Compound 109 of specific example (14).
3-(1-n-cutyl-2-methylindole-3-
yl)-3-(4-N,N-diethylamino-2-ethoxyphenyl)phthalide 1-electron accepting compound = 1.1-
Bis(4-hydroxyphenyl)cyclohegyusan89.
Zinc 4-β-p-methoxyphenoxyethoxysalicylate 89, 1-phenyl-2,3-dimethyl-3-pyrazolin-5-one complex of zinc rhodan 49 In all cases of Examples 2 to 3, the coloring obtained The images showed good resistance to chemicals, sunlight, etc.

(Example 4) (1) Preparation of capsule sheet containing electron-donating colorless dye Partial sodium salt of polyvinylbenzenesulfonic acid (manufactured by National Starch Co., Ltd., VER3A, Tl2O3) 5
1 part is dissolved in 95 parts of hot water and then cooled. A sodium hydroxide aqueous solution was added to this to adjust the pH to 4.0. On the other hand, 100 parts of diisopropylnaphthalene in which 3.5% of the compound of Example (1) was dissolved was emulsified and dispersed in 100 parts of a 5% aqueous solution of a partial sodium salt of the polyvinylbenzenesulfonic acid to form particles with a diameter of 4.0μ. An emulsion was obtained. Separately, 6 parts of melamine, 11 parts of 37% by weight formaldehyde aqueous solution
After heating and stirring 30 parts of water at 60° C. for 30 minutes, a transparent aqueous solution of melamine formaldehyde initial heavy metals was obtained.

This aqueous solution was mixed with the above emulsion. While stirring, the pH was adjusted to 6.0 with a 2M phosphoric acid solution, the temperature of the solution was raised to 65°C, and stirring was continued for 6 hours. This capsule liquid was cooled to room temperature and adjusted to pH 9.0 with an aqueous sodium hydroxide solution.

To this dispersion, 200 parts of a 10% by weight polyvinyl alcohol aqueous solution and 50 parts of starch particles were added and water was added to prepare a solution of a microcapsule dispersion with a solid content concentration of 20%.

This coating liquid was applied to a base paper of 50 q/m' with an air knife coater so that the solid content was 59/m', and dried to obtain a capsule sheet containing an electron-donating colorless dye.

(2) Preparation of electron-accepting compound sheet 3.5-bis-α-methylbenzylsalicylic acid zinc salt 1
0 part was added to 20 parts of 1-isobutylphenyl-2-phenylethane and dissolved. This was mixed with 50 parts of a 2% polyvinyl alcohol aqueous solution and 0.1 part of a 10% dodecylbenzenesulfonic acid triethanolamine salt aqueous solution and emulsified so that the average particle size was 3 μm.

Next, a dispersion consisting of 80 parts of calcium carbonate, 20 parts of zinc oxide, 1 part of sodium hexametaphosphate, and 200 parts of water was mixed with the above emulsion and added as a binder to 100 parts of a 10% PVA aqueous solution and carboxylic acid. Modified SBR
10 parts of latex (as solid content) was added and water was added so that the solid content concentration was 20% to obtain a coating liquid (A).

Next, 10 parts of the electron-accepting compound, 20 parts of Jilton clay
A dispersion liquid consisting of 200 parts of water, 60 parts of calcium carbonate, 20 parts of zinc oxide, 1 part of sodium hexametaphosphate, and 200 parts of water was dispersed using a sand grinder so that the average particle size was 3 μm.

Add 16 parts of 10% PVA aqueous solution and 10% PVA to this dispersion.
100 parts of an aqueous solution and 10 parts of carboxy-modified SBR latex (as solid content) were added, and water was added so that the solid content concentration was 20% to obtain a coating liquid (B).

Coating liquid (A) and coating liquid (B) were mixed at a ratio of 1:1 in terms of electron-accepting compound, and applied to 509 parts m' of base paper at 5.0 g/m'.
The mixture was coated using an air knife coater so that a solid content of 100% was coated, and dried to obtain an electron-accepting compound sheet.

The surface of the microcapsule sheet containing an electron-donating colorless dye is
When the electron-accepting compound sheet was stacked and a load of 600 kg/cnl was applied, the color quickly developed to blue-green. Moreover, the obtained colored image showed good resistance to chemicals, sunlight, etc.

(Example 5) In place of the electron-donating colorless dye of Example 4, specific example (1
An electron-donating colorless dye-containing microcapsule sheet was obtained in the same manner as in Example 4, except that the compound 9) was used. Lay this sheet surface on the electron-accepting compound sheet of Example 4 6
When a load of 00 kg/c+Tt was applied, the color quickly developed into bluish green. Moreover, the obtained colored image showed good resistance to chemicals, sunlight, etc.

(Example 6) The following was used in place of the electron-accepting compound sheet of Example 4.

(2°) Adjustment of electron-accepting compound sheet Acidic clay 100
were dispersed in 400 parts of a 0.5% aqueous sodium hydroxide solution, and then 20 parts of styrene-butadiene copolymer latex (solid content) and 40 parts of a 10% starch aqueous solution were added, thoroughly stirred and mixed, and the electron accepting A compound coating solution was obtained.

5. Apply the coating liquid thus prepared to 509 parts m' of base paper.
The mixture was coated using an air knife coater so that a solid content of Oc+/m' was coated and dried to obtain an electron-accepting compound sheet.

On this electron-accepting compound sheet, the surface of the electron-donating colorless dye-containing microcapsule sheet of Example 4 was layered for 600 kg.
g/cn? When a load was applied, the color quickly developed blue. Further, the obtained colored image had a high color density (color density = 0.42, measured with a Maches Co., Ltd. RD-918 densitometer) and showed good resistance to chemicals, sunlight, etc.

(Example 7) In place of the electron-donating colorless dye of Example 4, specific example (2
An electron-donating colorless dye-containing microcapsule sheet was obtained in the same manner as in Example 4, except that the compound 8) was used. This sheet surface was stacked on the electron-accepting compound sheet of Example 6 for 60 minutes.
When a load of 0 kg/clTI was applied, a blue color developed. Furthermore, the obtained colored image had a high color density (color density = 0.37) and showed good resistance to chemicals, sunlight, etc.

(Example 8) In place of the electron-donating colorless dye of Example 4, specific example (3
An electron-donating colorless dye-containing microcapsule sheet was obtained in the same manner as in Example 4, except that the compound 1) was used. This sheet surface was stacked on the electron-accepting compound sheet of Example 6 for 60 minutes.
When a load of 0 kg/cn (0 kg/cn) was applied, a blue color developed.The colored image obtained had a high color density (color density = 0.38) and showed good resistance to chemicals, sunlight, etc.

(Example 9) In place of the electron-donating colorless dye of Example 4, specific example (2
An electron-donating colorless dye-containing microcapsule sheet was obtained in the same manner as in Example 4 except that the compound 9) was used. This sheet surface was stacked on the electron-accepting compound sheet of Example 6 for 60 minutes.
When a load of 0 kg/cn (0 kg/cn) was applied, a blue color developed.The color image obtained had a high color density (color density = 0.37) and showed good resistance to chemicals, sunlight, etc.

(Example 10) In place of the electron-donating colorless dye of Example 4, specific example (5
An electron-donating colorless dye-containing microcapsule sheet was obtained in the same manner as in Example 4, except that the compound 2) was used. This sheet surface was stacked on the electron-accepting compound sheet of Example 6 for 60 minutes.
When a load of 0 kg/cra was applied, a blue color developed. Furthermore, the obtained colored image had a high color density (color density = 0.37) and showed good resistance to chemicals, sunlight, etc.

(Comparative Example) A microcapsule sheet containing an electron-donating colorless dye was obtained in the same manner as in Example 4, except that the following was used instead of the electron-donating colorless dye of Example 4. When this sheet surface was stacked on the electron-accepting compound sheet of Example 6 and a load of 600 kg/cnt was applied, a blue color developed, but the color density of the obtained colored image was low (color density = 0. 20).

Claims (3)

[Claims] (1) A recording material that utilizes color development due to contact between an electron-donating colorless dye and an electron-accepting compound, characterized in that a compound represented by the following general formula (I) is used as the electron-donating colorless dye. Recording materials ▲ Contains mathematical formulas, chemical formulas, tables, etc. ▼ (I) In the above formula, R_1 to R_4 are hydrogen atoms, alkyl groups, and aryl groups, R_5 to R_9 are hydrogen atoms or monovalent groups, m
, n is an integer from 1 to 4, R_1_0 is -XR_1_1
, -PO(OR_1_2)_2, -CR_1_3R_1
_4R_1_5, -NR_1_6R_1_7 (X represents an oxygen atom or a sulfur atom, and R_1_1 to R_1_7 represent a hydrogen atom or a monovalent group). (2) R_1_0 in general formula (I) is -CR_1_3
In the case of R_1_4R_1_5, R_1_3, R_1_4
, R_1_5 is an electron-withdrawing group, a recording material characterized by using the compound according to claim 1. (3) R_1 to R_4 in general formula (I) are hydrogen atoms,
Alkyl group, aryl group, R_5 to R_7 are hydrogen atoms, alkyl group, alkoxy group, alkylthio group, alkoxycarbonyl group, aryl group, aryloxy group, arylthio group, aryloxycarbonyl group, cyano group, R_8, R_9 are Hydrogen atom, alkyl group, aryl group, alkoxy group, aryloxy group, cyano group, nitro group, substituted amino group, hydroxy group, halogen atom, alkoxycarbonyl group, aryloxycarbonyl group,
Acyloxy group, m and n are integers from 1 to 4, R_1
_0 is -XR_1_1, -PO(OR_1_2)_2,
-CR_1_3R_1_4R_1_5, -NR_1_6
A recording material characterized by using the compound according to claim 2 representing R_1_7 [in the above formula, X is an oxygen atom or a sulfur atom, and R_1_1 is an alkyl group, an aryl group, a heterocyclic group, COR_1_6SO
_2R_1_9, N=CR_2_0R_2_1, NR_
2_2R_2_3 [R_1_8, R_1_9 are hydrogen atoms, alkyl groups, aryl groups, heterocyclic groups, R_2
_0, R_2_1, R_2_2, R_2_3 are hydrogen atoms, alkyl groups, aryl groups, heterocyclic groups, COR_2_4
, SO_2R_2_5 (R_2_4 and R_2_5 represent a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group)]. R_1_2 represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group. Furthermore, R_1_2 may be linked to each other to form a 4- to 12-membered ring structure that may contain a hetero atom. R_1_3, R_1_4, R_1_5 are hydrogen atoms, alkyl groups, aryl groups, alkoxy groups, aryloxy groups, alkylthio groups, arylthio groups, halogen atoms, cyano groups, nitro groups, SO_2R_2_6, COR_2_
7, NR_2_8R_2_9 [R_2_6, R_
2_7 is a hydrogen atom, an alkyl group, an aryl group, a heterocyclic group, an alkoxy group, an aryloxy group, an alkylthio group,
Arylthio group, hydroxy group, NR_3_0R_3_
1, R_2_8, R_2_9, R_3_0, R_3_
1 is a hydrogen atom, an alkyl group, an aryl group, a heterocyclic group, S
O_2R_3_2, COR_3_3(R_3_2, R_
3_3 represents a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group]. Further, R_1_3 and R_1_4 may be linked to each other to form a 4- to 12-membered ring structure that may contain a hetero atom. R_1_6, R_1_7 are hydrogen atoms, alkyl groups, aryl groups, heterocyclic groups, SO_2R_3_4, COR_3_
5, hydroxy group, NR_3_6R_3_7 [R
_3_4, R_3_5 are hydrogen atoms, alkyl groups, aryl groups, alkoxy groups, aryloxy groups, heterocyclic groups, N
R_3_8R_3_9, R_3_6, R_3_7, R
_3_8, R_3_9 are hydrogen atoms, alkyl groups, aryl groups, heterocyclic groups, SO_2R_4_0, COR_4_1
(R_4_0 and R_4_1 represent a hydrogen atom, an alkyl group, an aryl group, or a heterocyclic group)]. Furthermore, R_1_6
, R_1_7 may be linked to each other to form a 4- to 12-membered ring structure that may contain a hetero atom. ]