JP2011056860A - Reversible thermal recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reversible thermal recording material capable of forming and erasing an image with a clear contrast and exhibiting good color development sensitivity and excellent high-speed erasability. <P>SOLUTION: In the reversible thermal recording material, an ordinarily colorless or light-colored dye precursor, and a reversible color developer creating a colored state and a discolored state relatively by differences in a heating temperature and/or a cooling speed after heating are contained on a support. A phenolic compound is contained as the reversible color developer, and a quaternary ammonium salt compound is contained as a discoloring promotor. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a reversible thermosensitive recording material whose color tone reversibly changes by controlling thermal energy.

  In recent years, a reversible thermosensitive recording material that can form a temporary image and erase the image when it is no longer needed attracts attention. As a reversible thermosensitive recording material, usually a colorless or light dye precursor and a reversible color developer (hereinafter referred to as reversible developer) that develops color by heating the dye precursor and re-heats it to decolorize it. Heat-sensitive recording material using a colorant), heat-sensitive recording material in which organic low molecular weight substances such as higher fatty acids are dispersed in a resin such as vinyl chloride-vinyl acetate, and heat-sensitive recording in which two or more polymers having different refractive indexes are mixed. Materials etc. are known. In particular, a reversible thermosensitive recording material composed of a dye precursor and a reversible developer can form and erase recorded images with high contrast and high sensitivity many times. Have been widely used for the purpose of visualizing information in the card.

  A long-chain aliphatic hydrocarbon group is generally used as a heat-sensitive recording material using a colorless or light-colored dye precursor and a reversible developer that develops color by heating and re-colors the dye precursor by heating. It has been proposed to use a specific phenol compound possessed as a reversible developer (see, for example, Patent Document 1). However, the reversible thermosensitive recording material using such a material has problems such as a slow decoloring speed and a long time for rewriting and insufficient decoloring.

  Therefore, by using a specific phenol compound having a long-chain aliphatic hydrocarbon group as the reversible developer, the contrast between coloring and decoloring is high, and high-speed erasing is possible. A reversible thermosensitive recording material excellent in image stability has been proposed (see, for example, Patent Documents 2 and 3). However, many of these phenol compounds have a high melting point, and it is necessary to heat them to a high temperature during color development and erasing, and there is a problem that the recording material is greatly deteriorated with repeated printing and erasing.

  On the other hand, a phenol compound having a relatively low melting point has also been proposed as a reversible developer (see Patent Documents 4 and 5). However, reversible thermosensitive recording materials using these phenolic compounds have good color development sensitivity, but have a slow decoloring speed, leaving problems in high-speed erasure.

Japanese Patent Laid-Open No. 6-210954 Japanese Patent Laid-Open No. 7-179043 JP 2000-263946 A JP 7-68934 A Japanese Unexamined Patent Publication No. 2005-1127

  An object of the present invention is to provide a reversible thermosensitive recording material capable of forming and erasing an image having a clear contrast, having good color development sensitivity, and excellent in high-speed erasability.

  As a result of intensive studies on the color development sensitivity and high-speed erasability, the present inventors have found that the combination of a reversible developer and a decoloring accelerator used in combination with the reversible developer is important.

  That is, the present invention provides a reversible manifestation in which a normally colorless or light dye precursor is formed on a support, and a relatively colored state and a decolored state are formed depending on the heating temperature and / or the cooling rate after heating. The reversible thermosensitive recording material containing a colorant contains a phenol compound represented by the following general formula (1) as the reversible developer, and the general formula (2) below as a decoloring accelerator. A reversible thermosensitive recording material containing a quaternary ammonium salt compound represented by the formula:

（一般式（１）において、ｍは１から３の整数を表し、ｎは２０以上の整数を表す。Ｘはアミド基または尿素基を表す。）

(In General Formula (1), m represents an integer of 1 to 3, n represents an integer of 20 or more, and X represents an amide group or a urea group.)

（一般式（２）において、Ｒ_１、Ｒ_２およびＲ_３は同義であり、互いに同じであっても異なっていても良い炭素数１〜２４の飽和または不飽和の炭化水素基であって、そのうちの２つの炭化水素基は互いに結合して環を形成していても良い。Ｒ_４は炭素数６から２４の飽和または不飽和の炭化水素基を表す。ｐは１または２を表す。Ａはアニオンを表し、ｑおよびｒは分子内の電荷を０に調整するための整数を表す。）

(In the general formula (2), R ₁ , R ₂ and R ₃ are synonymous, and may be the same or different from each other, and may be a saturated or unsaturated hydrocarbon group having 1 to 24 carbon atoms, Two of these hydrocarbon groups may be bonded to each other to form a ring, R ₄ represents a saturated or unsaturated hydrocarbon group having 6 to 24 carbon atoms, and p represents 1 or 2. A Represents an anion, and q and r represent an integer for adjusting the charge in the molecule to 0.)

  According to the present invention, a reversible thermosensitive recording material capable of forming and erasing an image having a clear contrast, having good color development sensitivity, and excellent in high-speed erasability can be provided.

  The reversible thermosensitive recording material of the present invention will be described in detail below. The reversible thermosensitive recording material of the present invention forms a relatively colored state and a decolored state depending on the difference in heating temperature and / or cooling rate after heating. This basic coloring / decoloring phenomenon will be described.

  The principle of image formation and erasure of the reversible thermosensitive recording material of the present invention is not yet clear, but is considered as follows. Normally, when a colorless or light dye precursor is heated together with an electron-accepting compound such as a phenolic compound, electron transfer from the dye precursor to the electron-accepting compound occurs and color develops. At this time, it is considered that the electron-accepting compound molecule exists in the very vicinity of the colored dye molecule. When the electron-accepting compound molecule is separated from the colored dye molecule, the colored dye molecule receives electrons again and becomes a dye precursor state before coloring. In the present invention, it is considered that the distance between the electron-accepting compound molecule and the dye molecule is changed by heating to perform coloring and decoloring.

  More specifically, many of the electron-accepting compounds so far called reversible developers have long-chain aliphatic hydrocarbon groups in their structures, so that the dye precursor molecules and colored dye molecules It is considered that the compatibility of these materials is low, and in the solidified state, they hardly dissolve each other. Further, in a state where the dye precursor molecule and the reversible developer molecule can freely move as in the heat-melted state, the dye precursor molecule and the reversible developer molecule are melted at a certain ratio and become a colored state. Therefore, when the molten mixture that is colored is cooled slowly, the reversible developer molecule and the dye molecule become incompatible with each other as the temperature is lowered, resulting in a decolored state.

  The reversible developer in the present invention is composed of a phenol group as a color development site, a hydrogen bond group, and a long-chain aliphatic hydrocarbon as a basic skeleton that develops color development and decoloration, and balances these. However, studies focusing on hydrogen bonding groups have been made. This is because the strength of the hydrogen bonding group of the reversible developer has been considered important in order to realize high-speed erasure in the process of changing from the colored state to the decolored state. Therefore, it has been studied so far to make the hydrogen bonding group of the reversible developer molecule stronger or to increase the number of hydrogen bonding groups in the molecule. However, the reversible developer molecule has a strong hydrogen bonding group and the number of hydrogen bonding groups increases, so that the reversible developer has a high melting point, a high color development start temperature, and the sensitivity characteristics of the recording medium. The problem of deteriorating occurred.

  For this reason, the present inventors have studied focusing on an alkyl group (hereinafter also referred to as a spacer group) between a phenol group and a hydrogen bonding group as a basic skeleton that develops color development and decoloration. As a result, it was found that by introducing a methylene group having 1 to 3 carbon atoms as a spacer group, the melting point is lower than that of a reversible developer in which a hydrogen bond group is directly connected to a phenol group, and sensitivity is increased. . This is considered to be because the rigidity of the molecule is lowered because the phenol group and the hydrogen bonding group are spatially separated. In addition, as a result of studying hydrogen bond groups and long-chain aliphatic hydrocarbon groups, which are other basic skeletons that develop color development and decoloration, the use of an amide group or urea group as the hydrogen bond group is high. It was found that the color density and erasability can be obtained, and it was found that the stability of the color development state was improved by setting the alkyl group having 20 or more carbon atoms as the long-chain aliphatic hydrocarbon group.

  Furthermore, by adding a specific quaternary ammonium salt compound as a decoloring accelerator, the erasability is remarkably improved even when heated for a very short time without lowering the image storage stability, and further high-speed erasability can be achieved. It turns out that it will be realized. The reason for this is not clear, but the quaternary ammonium salt compound used in the present invention is present in a state that does not affect the aggregate structure formed by the reversible developer and dye precursor used in the present invention in the colored state. However, it is considered that in the decoloring process, it is in a state where it can quickly interact with the developer and / or dye precursor and expresses high-speed erasability.

  The reversible thermosensitive recording material of the present invention has a reversible color tone change on at least one side of a support, which is usually a colorless or light-colored dye precursor, due to a difference in heating temperature and / or cooling rate after heating. In the reversible thermosensitive recording material provided with a reversible thermosensitive recording layer containing a reversible color developer that causes a reversible color developer, the reversible color developer contains a phenol compound represented by the general formula (1). .

  In the general formula (1), m represents an integer of 1 to 3, and is preferably 1 or 2. n represents an integer of 20 or more, and the larger n is, the longer the aliphatic hydrocarbon group is. Therefore, the decoloring speed and the stabilization of the color image are improved. Therefore, the larger n is, the better the recording medium can be obtained. Can do. However, on the other hand, if the aliphatic hydrocarbon group becomes long, the raw material becomes expensive and difficult to obtain, which causes a problem in practicality. Therefore, n is preferably 20 to 36. X represents an amide group (—CONH—, —NHCO—) or a urea group (—NHCONH—).

  Specific examples of the reversible developer represented by the general formula (1) are given below, but the present invention is not limited thereto.

  N- [2- (p-hydroxyphenyl) ethyl] henicosanamide, N- [2- (p-hydroxyphenyl) ethyl] docosanamide, N- [2- (p-hydroxyphenyl) ethyl] tricosanamide, N- [2- (p-hydroxyphenyl) ethyl] tetracosanamide, N- [2- (p-hydroxyphenyl) ethyl] pentacosanamide, N- [2- (p-hydroxyphenyl) ethyl] hexacosanamide N- [2- (p-hydroxyphenyl) ethyl] heptacosanamide, N- [2- (p-hydroxyphenyl) ethyl] octacosanamide, N- [2- (p-hydroxyphenyl) ethyl] nonacosane Amide, N- [2- (p-hydroxyphenyl) ethyl] triacontanamid.

  N-icosyl- (p-hydroxyphenyl) acetamide, N-henicosyl- (p-hydroxyphenyl) acetamide, N-docosyl- (p-hydroxyphenyl) acetamide, N-tricosyl- (p-hydroxyphenyl) acetamide, N- Tetracosyl- (p-hydroxyphenyl) acetamide, N-pentacosyl- (p-hydroxyphenyl) acetamide, N-hexacosyl- (p-hydroxyphenyl) acetamide, N-heptacosyl- (p-hydroxyphenyl) acetamide, N-octacosyl- (P-hydroxyphenyl) acetamide, N-nonacosyl-p (p-hydroxyphenyl) acetamide, N-triacontyl- (p-hydroxyphenyl) acetamide, N-icosyl- [3- (p-hydroxy Enyl)] propionamide, N-henicosyl- [3- (p-hydroxyphenyl)] propionamide, N-docosyl- [3- (p-hydroxyphenyl)] propionamide, N-tricosyl- [3- (p- Hydroxyphenyl)] propionamide, N-tetracosyl- [3- (p-hydroxyphenyl)] propionamide, N-pentacosyl- [3- (p-hydroxyphenyl)] propionamide, N-hexacosyl- [3- (p -Hydroxyphenyl)] propionamide, N-heptacosyl- [3- (p-hydroxyphenyl)] propionamide, N-octacosyl- [3- (p-hydroxyphenyl)] propionamide, N-nonacosyl- [3- ( p-hydroxyphenyl)] propionamide, N-triacon Le - [3- (p-hydroxyphenyl)] propionamide.

  N- [2- (p-hydroxyphenyl) ethyl] -N'-icosylurea, N- [2- (p-hydroxyphenyl) ethyl] -N'-henicosylurea, N- [2- (p-hydroxyphenyl) ) Ethyl] -N'-docosylurea, N- [2- (p-hydroxyphenyl) ethyl] -N'-tricosylurea, N- [2- (p-hydroxyphenyl) ethyl] -N'-tetracosylurea, N- [2- (p-hydroxyphenyl) ethyl] -N'-pentacosylurea, N- [2- (p-hydroxyphenyl) ethyl] -N'-hexacosylurea, N- [2- (p-hydroxyphenyl) ) Ethyl] -N'-heptacosylurea, N- [2- (p-hydroxyphenyl) ethyl] -N'-octacosylurea, N- [2- (p-hydroxyphenyl) ethyl]- '- nonacosyl urea, N- [2- (p- hydroxyphenyl) ethyl]-N'-triacontyl urea.

  Although the synthesis example of the reversible developer represented by the general formula (1) is given below, the present invention is not limited to this.

(Synthesis Example 1)
<Reversible developer: N-triacontyl- [3- (p-hydroxyphenyl)] propionamide>
A reaction vessel was charged with 2.5 g of 3- (p-hydroxyphenyl) propionic acid, 6.6 g of triacontylamine, 0.4 g of 1-hydroxy benttriazole, 2.3 g of N, N′-diisopropylcarbodiimide, and 300 ml of ethyl acetate. Heated to reflux for 5 hours. After cooling the reaction solution to room temperature, the precipitated crystals were filtered off and washed with methanol. The compound was obtained by recrystallization using 2-propanol. The yield was 7.8 g, and the yield was 89%. The melting point was 116 ° C.

(Synthesis Example 2)
<Reversible developer; N- [2- (p-hydroxyphenyl) ethyl] -N'-nonacosyl urea>
9.0 g of triacontanoic acid and 100 ml of toluene were charged into the reaction vessel, and 5.7 g of diphenylphosphoric acid azide was further added, followed by heating at an internal temperature of 80 ° C. After confirming that the generation of nitrogen was completed and an isocyanate compound was formed, 3.0 g of tyramine was added to the reaction vessel, and the mixture was heated and stirred for 2 hours. After cooling the reaction solution to room temperature, the precipitated crystals were filtered off and washed with acetone. The compound was obtained by recrystallization using 2-propanol. The yield was 8.4 g, and the yield was 72%. The melting point was 132 ° C.

  Each of the reversible developers according to the present invention may be used alone or in combination of two or more. The usage-amount with respect to a dye precursor is 5-5000 mass%, Preferably it is 10-3000 mass%.

  Next, the reversible thermosensitive recording material of the present invention is reversible to at least one side of the support, usually a colorless or light dye precursor, and the dye precursor due to the difference in heating temperature and / or cooling rate after heating. In a reversible thermosensitive recording material provided with a reversible thermosensitive recording layer containing a reversible developer that causes a change in color tone, a quaternary ammonium salt compound represented by the general formula (2) is used as a decoloring accelerator. It contains.

In the general formula (2), R ₁ , R _2, and R ₃ are synonymous and each represents a saturated or unsaturated hydrocarbon group having 1 to 24 carbon atoms which may be the same as or different from each other, but branched. Represents an alkyl group, an alkenyl group, an aralkyl group, and an aryl group, which may be substituted, and these groups may be substituted with an alkyl group or an alkenyl group. Two of these hydrocarbon groups may be bonded to each other to form a ring. Among these, an aliphatic hydrocarbon group having 1 to 12 carbon atoms is preferable. R ₄ represents a saturated or unsaturated hydrocarbon group having 6 to 24 carbon atoms, p represents 1 or 2, and when p is 1, R ₄ represents an alkyl group, an alkenyl group, an alkynyl group, and p represents In the case of 2, R ₄ represents an alkylene group, an alkenylene group or an alkynylene group, and these groups may be further substituted with an alkyl group or an aralkyl group. A represents an anion, and is halogen, substituted sulfonate, substituted phosphate, substituted borate or substituted imide, preferably halogen or substituted sulfonate. q and r represent integers for adjusting the charge in the molecule to zero. That is, p = q × r.

  Although the specific example of the decoloring accelerator represented by General formula (2) below is given, this invention is not limited to this.

  n-octyltrimethylammonium chloride, n-decyltrimethylammonium chloride, n-dodecyltrimethylammonium chloride, n-tetradecyltrimethylammonium chloride, n-hexadecyltrimethylammonium chloride, n-octadecyltrimethylammonium chloride, n-docosyltrimethylammonium Chloride, benzyldimethyl-n-hexadecylammonium chloride, benzyldimethylphenylammonium chloride, benzyldimethyl-n-octadecylammonium chloride, benzyldimethyl-n-tetradecylammonium chloride, dimethyl-di-n-octadecylammonium chloride, methyl-tri -N-octylammonium chloride.

  n-octyltrimethylammonium bromide, n-decyltrimethylammonium bromide, n-dodecyltrimethylammonium bromide, n-tetradecyltrimethylammonium bromide, n-hexadecyltrimethylammonium bromide, n-octadecyltrimethylammonium bromide, n-docosyltrimethylammonium Bromide, dimethyl-di-n-octylammonium bromide, di-n-decyldimethylammonium bromide, di-n-dodecyldimethylammonium bromide, dimethyl-di-n-tetradecylammonium bromide, dimethyl-di-n-octadecylammonium bromide Di-n-hexadecyldimethylammonium bromide, ethyl-n-hexadecyldimethylammonium bromide, n Hexyl dimethyl -n- octyl ammonium bromide, tetra (n- octyl) ammonium bromide, tetra (n- decyl) ammonium bromide, decamethonium bromide.

  n-octyltrimethylammonium iodide, n-decyltrimethylammonium iodide, n-dodecyltrimethylammonium iodide, n-tetradecyltrimethylammonium iodide, n-hexadecyltrimethylammonium iodide, n-octadecyltrimethylammonium iodide, n-docosyltrimethylammonium iodide, tetra (n-hexyl) ammonium iodide, tetra (n-heptyl) ammonium iodide, tetra (n-octyl) ammonium iodide, decamethonium iodide.

  n-octyltrimethylammonium toluenesulfonate, n-octadecyltrimethylammonium toluenesulfonate, cyclohexyltrimethylammonium-bis (trifluoromethanesulfonyl) imide, n-hexadecyltrimethylammonium hexafluorophosphate, n-hexadecyltrimethylammonium tetrafluoroborate, methyl- Tri-n-octylammonium-bis (trifluoromethanesulfonyl) imide.

  The quaternary ammonium salt compounds used as the decoloring accelerator according to the present invention may be used alone or in combination of two or more. The usage-amount with respect to a reversible developer is 0.1-50 mass%, Preferably it is 1-30 mass%, Most preferably, it is 3-20 mass%.

  Furthermore, the reversible thermosensitive recording material of the present invention is reversible to at least one side of the support, usually a colorless or light dye precursor, and the dye precursor due to the difference in heating temperature and / or cooling rate after heating. In a reversible thermosensitive recording material provided with a reversible thermosensitive recording layer containing a reversible developer that causes a change in color tone, the dye precursor is not particularly limited and can be appropriately selected according to the purpose. Suitable examples include leuco dyes. As the leuco dye, a fluorane compound or an azaphthalide compound can be preferably used. Hereinafter, although the specific example of a dye precursor is given, this invention is not limited to this.

  2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6- (di-n-butylamino) fluorane, 2-anilino-3-methyl-6- (di-n-amylamino) ) Fluorane, 2-anilino-3-methyl-6- (di-isoamylamino) fluorane, 2-anilino-3-methyl-6- (Nn-propyl-N-methylamino) fluorane, 2-anilino-3 -Methyl-6- (N-isopropyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (N-isobutyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- ( Nn-amyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (N-sec-butyl-N-methylamino) fluorane, 2-anilino- -Methyl-6- (Nn-amyl-N-ethylamino) fluorane, 2-anilino-3-methyl-6- (N-isoamyl-N-ethylamino) fluorane, 2-anilino-3-methyl-6 -(Nn-propyl-N-isopropylamino) fluorane, 2-anilino-3-methyl-6- (N-cyclohexyl-N-methylamino) fluorane, 2-anilino-3-methyl-6- (N- Ethyl-p-toluidino) fluoran, 2-anilino-3-methyl-6- (N-methyl-p-toluidino) fluoran.

  2- (m-trichloromethylanilino) -3-methyl-6-diethylaminofluorane, 2- (m-trifluoromethylanilino) -3-methyl-6-diethylaminofluorane, 2- (m-trichloromethyl) Anilino) -3-methyl-6- (N-cyclohexyl-N-methylamino) fluorane, 2- (2,4-dimethylanilino) -3-methyl-6-diethylaminofluorane, 2- (2,4 -Dimethylanilino) -3-methyl-6- (di-n-butylamino) fluorane, 2- (m-toluidino) -3-methyl-6-diethylaminofluorane, 2- (m-toluidino) -3- Methyl-6- (di-n-butylamino) fluorane, 2- (p-toluidino) -3-methyl-6-diethylaminofluorane, 2- (p-toluidino) -3- Tyl-6- (di-n-butylamino) fluorane, 2- (N-ethyl-p-toluidino) -3-methyl-6- (N-ethylanilino) fluorane, 2- (N-ethyl-p-toluidino) -3-methyl-6- (N-propyl-p-toluidino) fluorane, 2-anilino-6- (Nn-hexyl-N-ethylamino) fluorane, 2- (o-chloroanilino) -6-diethylaminofluor Oran, 2- (o-chloroanilino) -6- (di-n-butylamino) fluorane, 2- (m-trifluoromethylanilino) -6-diethylaminofluorane, 2,3-dimethyl-6-dimethylamino Fluorane, 3-methyl-6- (N-ethyl-p-toluidino) fluorane, 2-chloro-6-diethylaminofluorane.

  2-bromo-6-diethylaminofluorane, 2-chloro-6- (di-n-propylamino) fluorane, 3-chloro-6-cyclohexylaminofluorane, 3-bromo-6-cyclohexylaminofluorane, 2- Chloro-6- (N-ethyl-N-isoamylamino) fluorane, 2-chloro-3-methyl-6-diethylaminofluorane, 2-anilino-3-chloro-6-diethylaminofluorane, 2- (o-chloroanilino) ) -3-Chloro-6-cyclohexylaminofluorane, 2- (m-trifluoromethylanilino) -3-chloro-6-diethylaminofluorane, 2- (2,3-dichloroanilino) -3-chloro -6-diethylaminofluorane, 1,2-benzo-6-diethylaminofluorane, 3-diethylamino- - (m-trifluoromethyl) -6-fluoran.

  3- (1-Ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-Ethoxy-4-diethylaminophenyl) -7-azaphthalide, 3- (1-octyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4- Azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (2-methyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3- Yl) -3- (2-methyl-4-diethylaminophenyl) -7-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (4-diethyl) Aminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- [4- (Nn-amyl-N-methylamino) phenyl] -4-azaphthalide, 3 -(1-Methyl-2-methylindol-3-yl) -3- (2-hexyloxy-4-diethylaminophenyl) -4-azaphthalide, 3,3-bis (2-ethoxy-4-diethylaminophenyl)- 4-Azaphthalide, 3,3-bis (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide.

  2- (p-acetylanilino) -6- (Nn-amyl-Nn-butylamino) fluorane, 2-benzylamino-6- (N-ethyl-p-toluidino) fluorane, 2-benzylamino -6- (N-methyl-2,4-dimethylanilino) fluorane, 2-benzylamino-6- (N-ethyl-2,4-dimethylanilino) fluorane, 2-benzylamino-6- (N- Methyl-p-toluidino) fluorane, 2-benzylamino-6- (N-ethyl-p-toluidino) fluorane, 2-bis (p-methylbenzylamino) -6- (N-ethyl-p-toluidino) fluorane, 2- (α-Phenylethylamino) -6- (N-ethyl-p-toluidino) fluorane.

  2-methylamino-6- (N-methylanilino) fluorane, 2-methylamino-6- (N-ethylanilino) fluorane, 2-methylamino-6- (Nn-propylanilino) fluorane, 2-ethylamino -6- (N-methyl-p-toluidino) fluorane, 2-methylamino-6- (N-methyl-2,4-dimethylanilino) fluorane, 2-ethylamino-6- (N-ethyl-2, 4-dimethylanilino) fluorane, 2-dimethylamino-6- (N-methylanilino) fluorane, 2-dimethylamino-6- (N-ethylanilino) fluorane, 2-diethylamino-6- (N-methyl-p-toluidino ) Fluorane, 2-diethylamino-6- (N-ethyl-p-toluidino) fluorane, 2-di-n-propylamino-6- N- methylanilino) fluoran, 2-di -n- propyl amino-6-(N- ethylanilino) fluoran.

  2-amino-6- (N-methylanilino) fluorane, 2-amino-6- (N-ethylanilino) fluorane, 2-amino-6- (Nn-propylanilino) fluorane, 2-amino-6- ( N-methyl-p-toluidino) fluorane, 2-amino-6- (N-ethyl-p-toluidino) fluorane, 2-amino-6- (Nn-propyl-p-toluidino) fluorane, 2-amino- 6- (N-methyl-p-ethylanilino) fluorane, 2-amino-6- (N-ethyl-p-ethylanilino) fluorane, 2-amino-6- (Nn-propyl-p-ethylanilino) fluorane, 2 -Amino-6- (N-methyl-2,4-dimethylanilino) fluorane, 2-amino-6- (N-ethyl-2,4-dimethylanilino) fluorane, 2 Amino-6- (Nn-propyl-2,4-dimethylanilino) fluorane, 2-amino-6- (N-methyl-p-chloroanilino) fluorane, 2-amino-6- (N-ethyl-p -Chloroanilino) fluoran, 2-amino-6- (Nn-propyl-p-chloroanilino) fluorane, 1,2-benzo-6- (N-ethyl-N-isoamylamino) fluorane, 1,2-benzo- 6-di-n-butylaminofluorane, 1,2-benzo-6- (N-methyl-N-cyclohexylamino) fluorane, 1,2-benzo-6- (N-ethyl-N-toluidino) fluorane.

  4,4'-bis (dimethylaminophenyl) benzhydrylbenzyl ether, N-chlorophenyl leucooramine, N-2,4,5-trichlorophenyl leucooramine, benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue, 3 -Methylspirodinaphthopyrans, 3-ethylspirodinaphthopyrans, 3,3'-dichlorospirodinaphthopyrans, 3-benzylspirodinaphthopyrans, 3-methylnaphthyl (3-methoxybenzo) spiropyrans, 3-propylspiros Benzopyran.

  These dye precursors may be used singly or in combination of two or more, and toning can also be performed by mixing dye precursors that develop colors in other colors. In addition, a multicolor reversible thermosensitive recording material or a full-color reversible thermosensitive recording material can be obtained by laminating layers that develop colors of different colors or arranging them on a plane. The dye precursor may be subjected to processing such as microencapsulation, resin coating, and composite particle formation with a resin.

  The support according to the present invention includes paper, non-woven fabric / woven fabric / knitted fabric, plastic film, resin-coated paper, synthetic paper, metal plate, metal foil, glass, quartz glass, silicon resin, aluminum oxide, silicon oxide Etc., or a combination of these can be arbitrarily used depending on the purpose. Examples of the plastic film that can be used in the present invention include polyester film, polyolefin film, polyvinyl alcohol film, polyvinyl chloride film, nylon film, polystyrene film, polyvinylidene chloride film, ethylene-vinyl acetate copolymer film, ethylene-vinyl. Examples include alcohol copolymer films, fluororesin films, polyimide films, aromatic polyamide films, acrylic (based) resin films, and polycarbonate films. A polyester film is preferable in terms of mechanical strength, smoothness, water resistance, solvent resistance, and heat resistance. These synthetic resin materials may be used alone or in combination of two or more.

  Examples of the polyester film include polyethylene terephthalate (PET), polybutylene terephthalate, poly-1,4-cyclohexanedimethylene terephthalate, polyxylylene terephthalate, polyethylene isophthalate, polyethylene-2,6-naphthalate (PEN). It is done. Preferred polyester films include PET films or PEN films that are excellent in toughness, heat resistance, chemical resistance, dimensional stability, transparency, and electrical insulation.

  The support may be opaque, translucent or transparent. In order to make the background appear white or other specific colors, a white pigment, a colored dye pigment, or air bubbles may be included in the support or on the surface. When the affinity when a coating layer such as a reversible thermosensitive recording layer is provided on the support is low, the support is obtained by corona discharge treatment, oxidation reaction treatment (chromic acid, etc.), etching treatment, easy adhesion treatment, antistatic treatment, etc. A modification treatment may be performed on the surface. There is no restriction | limiting in particular about a shape, a structure, a magnitude | size, etc. as a support body concerning this invention. Examples of the shape include a flat plate shape and a roll shape. The structure may be a single layer structure or a laminated structure, and the size can be appropriately selected according to the use of the reversible thermosensitive recording material.

  The thickness of the support according to the present invention can be appropriately selected according to the use of the reversible thermosensitive recording material, but is preferably 10 to 2000 μm, and more preferably 20 to 1000 μm.

  The reversible thermosensitive recording layer according to the present invention is coated with a reversible thermosensitive recording layer coating solution containing at least a dye precursor, a reversible developer, and a decoloring accelerator on at least one surface of the support. It is formed by forming a film. As a method for incorporating a dye precursor, a reversible developer, and a decoloring accelerator into a reversible thermosensitive recording layer coating solution, each compound is dissolved in a solvent alone or dispersed in a dispersion medium and then mixed. A method in which each compound is mixed and then dissolved in a solvent or dispersed in a dispersion medium, a method in which each compound is dissolved by heating, homogenized, cooled, and dissolved in a solvent or dispersed in a dispersion medium. However, it is not particularly limited. If necessary, a dispersing agent may be used during dispersion.

  As a solvent or dispersion medium, water; alcohols such as methanol, ethanol, n-propanol, 2-propanol, n-butanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone; methyl acetate, ethyl acetate , Esters such as butyl acetate, isobutyl acetate, isopropyl acetate, ethyl lactate, ethylene carbonate, ethers such as diethyl ether, glycol dimethyl ether, glycol diethyl ether, dioxane, dioxolane, tetrahydrofuran, benzene, toluene, xylene, cresol, styrene, etc. Aromatic hydrocarbons such as pentane, hexane and cyclohexane; methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, Ren chlorohydrin, chlorobenzene, halogenated hydrocarbons such as dichlorobenzene; N, N- dimethylformamide, N, etc. amides such as N- dimethylacetamide can be used.

  For the purpose of improving the strength of the reversible thermosensitive recording layer, it is also possible to add a binder resin to the reversible thermosensitive recording layer. Specific examples of the binder resin include starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, polyacrylic acid soda, (meth) acrylic acid amide- (meth) acrylic acid ester copolymer Polymer, (meth) acrylic acid amide- (meth) acrylic acid ester- (meth) acrylic acid terpolymer, alkali salt of styrene-maleic anhydride copolymer, alkali salt of ethylene-maleic anhydride copolymer , Polyvinyl acetate, polyurethane, poly (meth) acrylic acid ester, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, methyl (meth) acrylate-butadiene copolymer, ethylene-vinyl acetate copolymer, ethylene -PVC Alcohol copolymer, polyvinyl chloride, ethylene - vinylidene chloride copolymer, polyvinylidene chloride, polycarbonates, polyvinyl butyral, and the like. The role of these binder resins is to keep the respective materials contained in the reversible thermosensitive recording layer uniformly dispersed without being displaced by heat application for image recording or image erasing. Therefore, it is preferable to use a resin having high heat resistance as the binder resin. When heat resistance, water resistance, and adhesiveness are required, a curable resin is particularly preferable.

  Examples of the curable resin include a thermosetting resin, an electron beam curable resin, and an ultraviolet curable resin. When a thermosetting resin is applied, a liquid containing a crosslinking agent is applied and formed into a film, and then crosslinked by heat. Specific examples of the thermosetting resin include epoxy resins, urea resins, xylene-formaldehyde resins, melamine resins, guanamine resins, phenol resins, phenoxy resins, saturated polyester resins, unsaturated polyester resins, and polyol resins. In addition, examples of the curing agent used in these thermosetting resins include organic acids, amines, isocyanates, epoxies, phenols, and the like. It only has to be selected. Among these, a crosslinked resin obtained by thermosetting a polyol compound with an isocyanate compound described in JP-A-10-230680 and JP-A-11-58963 is preferable.

  As oligomers / monomers used for electron beam curable resins or UV curable resins, there are many types of acrylic oligomers / monomers with excellent radiation curing properties, polyene-thiol oligomers / monomers, and photocationic polymerization type epoxy. Examples include oligomers and monomers. Examples of the acrylic monomer include a monofunctional monomer, a bifunctional monomer, and a polyfunctional monomer. In particular, a photopolymerization initiator and a photopolymerization accelerator are used at the time of ultraviolet crosslinking.

  Examples of the acrylic oligomer / monomer include polyester acrylate, polyether acrylate, epoxy acrylate, polyurethane acrylate, silicone acrylate, melamine acrylate, polybutadiene acrylate, and the like.

  In the reversible thermosensitive recording layer according to the present invention, a binder resin formed by crosslinking a polyol compound and an isocyanate compound, which is a preferable binder resin, will be described. Examples of the polyol compound include poly (meth) acryl polyol, polyester polyol, polycarbonate polyol, polyester polycarbonate polyol, polyether polyol, alkyd polyol, caprolactone polyol, and silicone polyol.

  Poly (meth) acrylic polyol is a copolymer of acrylic acid, methacrylic acid and esters thereof, which contains a hydroxyl group, and the copolymer component containing a hydroxyl group includes hydroxyethyl acrylate, methacrylic acid. Hydroxyethyl acid, hydroxypropyl acrylate, hydroxypropyl methacrylate, 3-chloro-2-hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl methacrylate, allyl alcohol and the like are used. Examples of copolymer components other than acrylic acid, methacrylic acid and esters thereof include styrene, α-methylstyrene, vinyltoluene, acrylamide, methacrylamide and derivatives thereof, vinyl acetate, maleic anhydride and the like.

  Polyester polyol refers to a condensate of a polybasic acid and a polyhydric alcohol having a hydroxyl group. Polybasic acids used in these are phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid. , Aromatic polybasic acids such as trimesic acid, pyromellitic acid, naphthalenedicarboxylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, 2-methylsuccinic acid, 2-methyladipic acid, 3-methyladipic acid, 3-methylpentanedioic acid, 2-methyloctanedioic acid, 3,7-dimethyldecanedioic acid, 3,8-dimethyldecanedioic acid, There are aliphatic polybasic acids such as dimer acid, and acid anhydrides obtained from these polybasic acids are also used.

  Polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, propanediol, neopentyl glycol, glycerin, trimethylolethane, trimethylolpropane, diglycerol, pentaerythritol, dipentaerythritol, di In addition to low molecular weight polyols such as acetone glycol and hexanetriol, high molecular weight polyols such as polyethylene glycol, polypropylene glycol and polybutylene glycol are also used. In addition to polyester polyols obtained from these, hydroxycarboxylic acids, or condensates or ring-opening polymerizations of cyclic lactones thereof, such as polybutyrolactone polyols, polycaprolactone polyols, and higher fatty acids in addition to the above polybasic acids and polyhydric alcohols. There are alkyd polyols obtained by condensation. The polyether polyol is a polymer having a main chain composed of an ether bond, and includes polyethylene glycol, polypropylene glycol, polyethylene glycol, and these branched esters.

  Examples of polyether polyols include ethylene oxide and / or propylene oxide adducts of polyhydric alcohols, polytetramethylene glycol, and the like. Examples of the silicone polyol include silicone oils having a siloxane bond in the molecule and a terminal hydroxyl group.

  In addition, fluorine-containing polyols such as hydroxyl-containing fluoroolefin, polyol hydroxyl-terminated polybutadiene, polyisoprene, hydrogenated polybutadiene, hydrogenated polyisoprene, polyurethane and the like can be used. Further, low molecular weight polyols such as diethylene glycol, triethylene glycol, glycerol, trimethylolpropane, pentaerythritol, 1,4-cyclohexadiol, 1,4-dihydroxybenzene, bisphenol A, bisphenol F, and other aliphatic, fatty A cyclic, aromatic polyhydric alcohol or polyhydric phenol or a condensate thereof is used as a reactive diluent.

  As the polyol compound according to the present invention, poly (meth) acrylic polyol and polyester polyol are preferable from the comprehensive evaluation of additive dispersibility, coating property, adhesiveness, heat resistance and film strength. The polyol compound according to the present invention may be used alone or in combination with one or more other polyol compounds having different polyol parts or other partial structures or different molecular weights.

  A well-known thing can be used as an isocyanate compound concerning this invention. For example, aromatic aliphatic diisocyanates such as phenylene diisocyanate (PDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), 4,4'-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), hydrogenated TDI, water A trifunctional or more polyfunctional polyhydride such as a polyol adduct, a buret trimer, an aliphatic or alicyclic diisocyanate such as XDI, hydrogenated MDI, hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI). In addition to isocyanate, various oligomers and polymers containing isocyanate may be mentioned. In the present invention, when xylylene diisocyanate or toluene isocyanate is used as the isocyanate compound, the color density is preferably improved, and further, xylylene diisocyanate having a high background whiteness is more preferable.

  The isocyanate compound according to the present invention may be used in combination with one or more isocyanates with respect to one or more polyol compounds. When a plurality of isocyanate compounds and polyol compounds are used, the combination may be arbitrary.

  The mixture of the polyol compound and the polyisocyanate compound may be used as it is when the mixture is liquid, but it can also be diluted with a non-reactive solvent with the polyisocyanate compound. As the solvent that can be used, a solvent that dissolves the polyol compound and the polyisocyanate compound and disperses and dissolves the dye precursor and the reversible developer is preferable. Specifically, the solvents exemplified in the method for incorporating the dye precursor and the reversible developer into the reversible thermosensitive recording layer coating liquid can be used. Among them, it is preferable to use an organic solvent that does not have active hydrogen that is reactive with the polyisocyanate compound. The crosslinking reaction between the polyol compound and the polyisocyanate compound may be performed at a reaction temperature of 30 to 160 ° C. and a reaction time of 1 minute to 120 hours. Needless to say, it takes a long time when the reaction temperature is low, and a short time at a high temperature.

  The amount of binder resin used in the reversible thermosensitive recording layer according to the present invention is preferably such that the mass percentage of the binder resin relative to the total mass of the reversible thermosensitive recording layer is in the range of 35% to 65%. If it is larger than this range, the color density may decrease significantly. On the other hand, if it is smaller than this range, the heat resistance and mechanical strength of the reversible thermosensitive recording layer may be lowered, the layer may be deformed, and the color density may be lowered. The mass percentage of the binder resin in the reversible thermosensitive recording layer is more preferably from 40% to 60%, particularly preferably from 45% to 55%.

  A binder resin can be added to the reversible thermosensitive recording layer coating liquid as necessary, but for the purpose of further improving the coating property or recording characteristics, a leveling agent, a dispersing agent, a hardener, Surfactant, thickener, antifoaming agent, antioxidant, anti-aging agent, filler, pigment, lubricant, antistatic agent, ultraviolet absorber, infrared absorber, colored dye / pigment, fluorescent whitening agent, heat fusible , A reversible thermosensitive recording layer, and the like can be incorporated into the reversible thermosensitive recording layer.

  When the reversible thermosensitive recording layer contains a curable resin, heating, ultraviolet irradiation, and electron beam irradiation are performed. Ultraviolet irradiation can be performed using a known ultraviolet irradiation device, and examples thereof include a light source, a lamp, a power source, a cooling device, and a conveying device. Examples of the light source include a mercury lamp, a metal halide lamp, a gallium lamp, a mercury xenon lamp, and a flash lamp. The wavelength of the light source can be appropriately selected according to the ultraviolet absorption wavelength of the photopolymerization initiator and the photopolymerization accelerator. The output and conveying speed of the ultraviolet irradiation are determined according to the irradiation energy necessary for crosslinking the ultraviolet curable resin.

  As the heat fusible substance which is an additive for adjusting the color development sensitivity and / or decoloring temperature of the reversible thermosensitive recording layer, those having a melting point of 60 ° C. to 200 ° C. are preferable, and in particular, 80 ° C. to 180 ° C. Those having a melting point of Sensitizers used for general heat-sensitive recording paper can also be used. For example, waxes such as N-hydroxymethyl stearic acid amide, behenic acid amide, stearic acid amide, and palmitic acid amide, naphthol derivatives such as 2-benzyloxynaphthalene, and biphenyl derivatives such as p-benzylbiphenyl and 4-allyloxybiphenyl 1, 2-bis (3-methylphenoxy) ethane, 2,2′-bis (4-methoxyphenoxy) diethyl ether, polyether compounds such as bis (4-methoxyphenyl) ether, diphenyl carbonate, dibenzyl oxalate, Carbonic acid or oxalic acid diester derivatives such as bis (p-methylbenzyl) oxalate can be used in combination.

  Anti-aging agents added for the purpose of preventing aging of the reversible thermosensitive recording layer include amine compounds such as p, p'-diaminodiphenylmethane, aldol-α-naphthylamine, and N, N'-diphenyl-p-phenylenediamine. , Hydroquinone monobenzyl ether, phenol compounds such as 1,1-bis (p-hydroxyphenyl) cyclohexane, benzotriazole compounds, triazine compounds, benzophenone compounds, benzoates and the like. In addition, o-phenylenethiourea, zinc salt of 2-aminobenzimidazole, nickel dibutylthiocarbamate, zinc oxide, paraffin and the like can be mentioned. In addition, a polymer containing these monomers having an anti-aging structure as a component of polymerization, and a polymer main chain grafted with an anti-aging structure can also be used. Two or more types of anti-aging agents can be used in combination.

  Examples of pigments that can be added to the reversible thermosensitive recording layer include, for example, carbonates such as aluminum, zinc, calcium, magnesium, barium, and titanium, oxides, hydroxides, sulfates, etc., and zeolite, silica, Inorganic pigments containing clays such as kaolin, calcined kaolin and talc, starch, styrene resin, polyolefin resin, urea-formalin resin, melamine resin, acrylic resin, paraffin, natural wax, synthetic wax and the like can be used. Further, higher fatty acid metal salts such as zinc stearate and calcium stearate can be used as a lubricant.

  The film thickness of the reversible thermosensitive recording layer according to the present invention is determined by its composition and desired color density, and specifically, it is preferably in the range of 0.5 to 20 μm, more preferably 3 to 15 μm. .

  In the present invention, it is preferable to provide a protective layer on the reversible thermosensitive recording layer for the purpose of enhancing durability during repeated use. The protective layer may be composed of a single layer or a plurality of layers of two layers or three or more layers. The protective layer preferably contains a curable resin such as a thermosetting resin, an electron beam curable resin, or an ultraviolet curable resin, and particularly preferably an electron beam curable resin or an ultraviolet curable resin. As the curable resin, resins exemplified as binder resins that can be used in the reversible thermosensitive recording layer can be used. Further, a pigment may be blended for the purpose of further improving durability or adjusting the glossiness, or a higher fatty acid metal salt or the like may be blended as a lubricant. As the pigment and the higher fatty acid metal salt, the compounds exemplified in the reversible thermosensitive recording layer can be used.

  The thickness of the protective layer is preferably in the range of 0.1 to 10 μm, more preferably 0.5 to 5 μm. When the film thickness exceeds 10 μm, not only the effect is saturated, but also the sensitivity of the reversible thermosensitive recording layer tends to decrease. When the film thickness is smaller than 0.1 μm, it is difficult to obtain the expected coating layer strength, and the coating layer is easily damaged.

  In the present invention, an intermediate layer is provided between the reversible thermosensitive recording layer and the protective layer for the purpose of improving weather resistance or the like, or an undercoat layer is provided between the support and the reversible thermosensitive recording layer for the purpose of improving the color development sensitivity. Alternatively, a light reflection layer or an air layer may be provided. The intermediate layer may contain an ultraviolet absorber. In the case where the reversible thermosensitive recording layer is provided only on one side of the support, a back coat layer may be provided on the other side. Examples of the ultraviolet absorber include a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, and a salicylic acid phenyl ester ultraviolet absorber. The undercoat layer may contain hollow particles. These layers may be composed of a single layer or a plurality of layers of two or more layers. Moreover, it is preferable that these layers contain curable resins, such as a thermosetting resin, an electron beam curable resin, and an ultraviolet curable resin.

  In the present invention, a leveling agent, a dispersant, a hardener, a surfactant, a thickener, a hardener is optionally added to the protective layer, intermediate layer, undercoat layer and the like provided on the support. Various additives such as preservatives, fillers, coloring dyes, fluorescent brighteners, ultraviolet absorbers, infrared absorbers, antioxidants, antioxidants, pH regulators, antifoaming agents, pigments, lubricants, antistatic agents, etc. An agent can be added.

  The reversible thermosensitive recording material of the present invention may be provided with a printing recording layer such as printing such as offset printing or gravure printing; an ink jet recording layer, a thermal transfer image receiving layer, a sublimation thermal transfer image receiving layer. These print and print recording layers may be provided by being laminated with the reversible thermosensitive recording layer, or may be provided on a part of the same surface as the reversible thermosensitive recording layer. Further, it may be provided on a part of or the entire surface opposite to the surface provided with the reversible thermosensitive recording layer. An overprint varnish (OP varnish) layer mainly composed of a curable resin may be provided partially or entirely on the print recording layer.

  In the reversible thermosensitive recording material of the present invention, in the reversible thermosensitive recording layer, other layers, the surface provided with the reversible thermosensitive recording layer, the opposite surface, etc. are electrically, magnetically and optically information. May contain a recordable material. Further, the support may be a multilayer and an IC chip may be sandwiched between them. Further, an antistatic layer can be provided on one side or both sides for the purpose of antistatic. The reversible thermosensitive recording material of the present invention can be attached to another medium through an adhesive layer or the like, or using a heat-fusible resin as a support.

  When the IC chip is encapsulated between the layers of the reversible thermosensitive recording material, for example, it can be encapsulated between the layers of the plastic film or between the paper substrate and the plastic film. It is preferable from the viewpoint of print quality that sealing is performed between layers away from the reversible thermosensitive recording layer. When a non-contact IC chip is encapsulated, it can be encapsulated with an antenna. A cushion layer can be provided for the purpose of preventing the IC chip from being damaged by the pressure during encapsulation. The thickness of the cushion layer is preferably 10 μm or more because cushioning properties are insufficient if it is less than 10 μm. In addition, since a load is applied to the joint between the IC chip and the antenna, the area of the cushion layer is preferably large enough to cover the IC chip and the antenna joint. The cushion layer can be provided on one side or both sides. More preferably, cushion layers are provided on both sides. As the cushion layer, a thermoplastic resin is preferable, and if it is a foamed resin, the cushioning property is better, so that the IC chip can be prevented from being damaged.

  The method of laminating each layer in the present invention on a support to form a reversible thermosensitive recording material is not particularly limited, and can be formed by a conventional method. For example, air knife coater, blade coater, bar coater, curtain coater, gravure roll and transfer roll coater, roll coater, comma coater, smoothing coater, micro gravure coater, reverse roll coater, 4 roll roll coater, dip coater, Various coating machines such as a rod coater, a kiss coater, a gate roll coater, a squeeze coater, a slide coater, a die coater and other smearing apparatuses, a planographic plate, a relief plate, an intaglio plate, a flexo, a gravure, a screen, and a hot melt can be used. Furthermore, each layer can be held by ultraviolet irradiation or electron beam irradiation, aging by heating, or the like, in addition to a normal drying step. By these methods, it is possible to apply and print one layer at a time or multiple layers simultaneously.

  In the reversible thermosensitive recording material of the present invention, rapid cooling is required following heating to form a color-recorded recording image, and a slow cooling rate after heating is sufficient to erase the recorded image. For example, after heating by an appropriate method, a colored state can be developed by rapidly cooling by pressing a low-temperature metal block or the like. In addition, if the heating is performed for a very short time using a thermal head, laser light, or the like, the cooling is performed immediately after the heating is completed, so that the colored state can be maintained. On the other hand, when heated for a relatively long time with a suitable heat source (thermal head, laser light, heat roll, heat stamp, high-frequency heating, electric heater, radiant heat from a light source such as a tungsten lamp or halogen lamp, hot air, etc.) Since not only the layer but also the support and the like are heated, even if the heat source is removed, the cooling rate is slow, and the color is lost. Therefore, even when the same heating temperature and the same heat source are used, the coloring state and the decoloring state can be arbitrarily expressed by controlling the cooling rate.

  Examples of the laser used for heating include, but are not limited to, a semiconductor laser, a YAG laser, and a carbon dioxide gas laser. In order to efficiently perform heating with a semiconductor laser or a YAG laser, a reversible thermosensitive recording layer contains a photothermal conversion material having absorption in the near infrared region, or a photothermal conversion layer containing a photothermal conversion material is reversible. It is preferably provided directly adjacent to the thermal recording layer. Examples of photothermal conversion materials having absorption in the near infrared region include, for example, metal or metalloid layers such as platinum, titanium, silicon, chromium, nickel, germanium, and aluminum, immonium compounds, metal complex compounds, cyanine dyes, squarylium dyes, Photothermal conversion dyes such as naphthoquinone dyes, phthalocyanine compounds, and polymethine compounds can be used, and can be contained in the reversible thermosensitive recording layer in a dispersed state or in a molecular state. Preferable photothermal conversion dyes include phthalocyanine compounds and metal complex compounds in terms of photothermal conversion efficiency, solubility in solvents, dispersibility in resins, and light resistance to ultraviolet light, and phthalocyanine compounds are particularly preferable. When the photothermal conversion layer is provided in the vicinity of the reversible thermosensitive recording layer, a photothermal conversion layer made of a metal film such as a copper thin film or ITO can also be used.

  Examples of phthalocyanine compounds include naphthalocyanine compounds, metal-free phthalocyanine compounds, iron phthalocyanine compounds, copper phthalocyanine compounds, zinc phthalocyanine compounds, nickel phthalocyanine compounds, vanadyl phthalocyanine compounds, indium chloride phthalocyanine compounds, tin phthalocyanine compounds, and more preferably. Are vanadyl phthalocyanine compounds, zinc phthalocyanine compounds, and tin phthalocyanine compounds. The phthalocyanine compound used in the present invention may have a substituent on the aromatic ring for the purpose of adjusting the absorption wavelength, improving the solubility in a solvent, improving light resistance, and the like. Examples of the substituent include an alkyl ether group, an alkyl thioether group, an aryl ether group, an aryl thioether group, an amide group, an amino group, an alkyl ester group, an aryl ester group, a chlorine atom, and a fluorine atom. When the aromatic ring has two or more substituents, they may be the same or different, and the substituents may be bonded to form a ring.

The amount of the photothermal conversion dye used is preferably set so that the absorbance at the oscillation wavelength of the light source used is 0.2 or more. If it is less than this amount, sufficient heat generation cannot be obtained, and the recording sensitivity is lowered. On the other hand, the photothermal conversion dye has some absorption in the visible region, and if the amount used is too large, the contrast is lowered. It is preferable to set an upper limit for the amount of photothermal conversion dye used so that an average transmittance of 400 nm to 700 nm can be secured by 60% or more. Two or more kinds of photothermal conversion dyes can be mixed and used.

  The photothermal conversion dye is preferably contained in at least one of the same layer or adjacent layers with respect to the layer containing the leuco dye and the reversible developer, and preferably contained in the same layer. It is more preferable for obtaining sensitivity.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to this Example. In addition, the number of parts in an Example is a mass reference | standard.

Example 1
(A) Preparation of reversible thermosensitive recording layer coating solution As a dye precursor, 20 parts of 2- (p-toluidino) -3-methyl-6-diethylaminofluorane, and as a reversible developer, N- [2- ( p-Hydroxyphenyl) ethyl] docosanamide 100 parts, n-octadecyltrimethylammonium chloride 5 parts as an erasing accelerator, polyester polyol (manufactured by DIC Corporation, trade name: Burnock 11-408, active ingredient 70 mass%) 100 parts A mixture of 950 parts of methyl ethyl ketone was dispersed with a glass bead for 5 hours using a paint shaker to obtain a dispersion. To the dispersion thus obtained, 130 parts of an isocyanate compound (manufactured by Mitsui Chemicals, trade name: Takenate D-110N, active ingredient: 75% by mass) and 62 parts of methyl ethyl ketone are added and mixed well, and reversible thermosensitive. A recording layer coating solution was prepared.

(B) Coating of reversible thermosensitive recording layer coating liquid The reversible thermosensitive recording layer coating liquid obtained in (A) is applied to a white polyethylene terephthalate (PET) sheet having a thickness of 250 μm with a dry coating amount of 10 g / m ^2. Then, after drying at 100 ° C. for 1 minute, it was further cured by heating at 50 ° C. for 24 hours to form a reversible thermosensitive recording layer.

(C) Preparation of intermediate layer coating solution 50 parts of 2,2'-methylenebis [6- (2H-benzotriazol-2-yl) -4- (2-hydroxyethyl) phenol] as a UV absorber, polyester polyol (DIC) Co., Ltd., trade name: Bernock 11-408, active ingredient 70 mass%) 100 parts and a mixture of 800 parts of methyl ethyl ketone were dispersed together with glass beads for 5 hours with a paint shaker to obtain a dispersion. To the dispersion thus obtained, 140 parts of an isocyanate compound (trade name: Takenate D-110N, active ingredient 75% by mass, manufactured by Mitsui Chemicals, Inc.) and 50 parts of methyl ethyl ketone were added and mixed well, and the intermediate layer coating solution was added. Was prepared.

(D) Coating of intermediate layer coating liquid On the reversible thermosensitive recording layer coated surface of the coated sheet prepared in (B), the dry coating amount of the intermediate layer coating liquid obtained in (C) is 2 g / m ^2. And dried at 100 ° C. for 1 minute, and further cured by heating at 50 ° C. for 24 hours to provide an intermediate layer.

(E) Preparation of coating solution for protective layer Urethane acrylate UV curable resin (manufactured by DIC Corporation, trade name: Unidic 17-813, active ingredient: 80% by mass) 12.5 parts, wet method silica (Fuji Silysia Chemical) (Product name: Silicia 350) 2.0 parts and butyl acetate 10 parts were mixed. The liquid mixture thus obtained was treated with a bead mill to prepare a protective layer coating solution.

(F) Coating of protective layer coating liquid On the intermediate layer coating surface of the coating sheet prepared in (D), the dry coating amount of the protective layer coating liquid obtained in (E) is 3 g / m ^2. The film is dried at 120 ° C. for 1 minute and then cured by passing it through an ultraviolet lamp with an irradiation energy of 120 W / cm at a conveying speed of 10 m / min to provide a protective layer. The reversible thermosensitive recording material of Example 1 Got.

(Example 2)
Instead of using 100 parts of N- [2- (p-hydroxyphenyl) ethyl] docosanamide as the reversible developer in Example 1 (A), N-docosyl- (p-hydroxyphenyl) as the reversible developer ) A reversible thermosensitive recording material of Example 2 was obtained in the same manner as in Example 1 except that 100 parts of acetamide was used.

(Example 3)
In Example 1 (A), instead of using 100 parts of N- [2- (p-hydroxyphenyl) ethyl] docosanamide as the reversible developer, N-docosyl- [3- (p -Hydroxyphenyl)] propionamide was used, except that 7 parts of n-hexadecyltrimethylammonium chloride was used as a decoloring accelerator instead of 5 parts of n-octadecyltrimethylammonium chloride as a decoloring accelerator. In the same manner as in Example 1, a reversible thermosensitive recording material of Example 3 was obtained.

Example 4
Instead of using 100 parts of N- [2- (p-hydroxyphenyl) ethyl] docosanamide as the reversible developer in Example 1 (A), N-triacontyl- (p-hydroxyphenyl) as the reversible developer ) A reversible thermosensitive recording material of Example 4 was obtained in the same manner as in Example 1 except that 90 parts of acetamide was used.

(Example 5)
In Example 1 (A), instead of using 100 parts of N- [2- (p-hydroxyphenyl) ethyl] docosanamide as the reversible developer, N-triacontyl- [3- (p -Hydroxyphenyl)] propionamide was used except that 5 parts of n-docosyltrimethylammonium chloride was used as a decoloring accelerator instead of 5 parts of n-octadecyltrimethylammonium chloride as a decoloring accelerator. In the same manner as in Example 1, the reversible thermosensitive recording material of Example 5 was obtained.

(Example 6)
Instead of using 100 parts of N- [2- (p-hydroxyphenyl) ethyl] docosanamide as the reversible developer in Example 1 (A), N- [2- (p-hydroxy) as the reversible developer. A reversible thermosensitive recording material of Example 6 was obtained in the same manner as in Example 1 except that 120 parts of (phenyl) ethyl] -N'-henicosylurea was used.

(Example 7)
Instead of using 100 parts of N- [2- (p-hydroxyphenyl) ethyl] docosanamide as the reversible developer in Example 1 (A), N- [2- (p-hydroxy) as the reversible developer. Phenyl) ethyl] -N'-nonacosylurea 110 parts, and 5 parts of n-hexadecyltrimethylammonium bromide was used as a decoloring accelerator instead of 5 parts of n-octadecyltrimethylammonium chloride as a decoloring accelerator A reversible thermosensitive recording material of Example 7 was obtained in the same manner as Example 1 except for the above.

(Example 8)
Instead of using 100 parts of N- [2- (p-hydroxyphenyl) ethyl] docosanamide as the reversible developer in Example 1 (E), N- [2- (p-hydroxy) as the reversible developer. Phenyl) ethyl] -N'-triacontylurea was used in 100 parts, and instead of using 5 parts of n-octadecyltrimethylammonium chloride as a decoloring accelerator, 5 parts of n-octadecyltrimethylammonium toluenesulfonate was used as a decoloring accelerator. A reversible thermosensitive recording material of Example 8 was obtained in the same manner as Example 1 except for the above.

(Comparative Example 1)
In Example 1 (A), a reversible thermosensitive recording material of Comparative Example 1 was obtained in the same manner as in Example 1 except that 5 parts of n-octadecyltrimethylammonium chloride was not added as a decoloring accelerator.

(Comparative Example 2)
Instead of using 100 parts of N- [2- (p-hydroxyphenyl) ethyl] docosanamide as the reversible developer in Example 1 (A), N- [2- (p-hydroxy) as the reversible developer. A reversible thermosensitive recording material of Comparative Example 2 was obtained in the same manner as in Example 1 except that 100 parts of (phenyl) ethyl] octadecanamide was used.

(Comparative Example 3)
Instead of using 100 parts of N- [2- (p-hydroxyphenyl) ethyl] docosanamide as the reversible developer in Example 1 (A), N- [2- (p-hydroxy) as the reversible developer. A reversible thermosensitive recording material of Comparative Example 3 was obtained in the same manner as in Example 1 except that 100 parts of (phenyl) ethyl] -N'-octadecylurea was used.

(Comparative Example 4)
Instead of using 100 parts of N- [2- (p-hydroxyphenyl) ethyl] docosanamide as the reversible developer in Example 1 (A), N- [3- (p-hydroxy) as the reversible developer. A reversible thermosensitive recording material of Comparative Example 4 was obtained in the same manner as in Example 1 except that 100 parts of (phenyl) propiono] -N'-docosanohydrazide was used.

(Comparative Example 5)
Instead of using 100 parts of N- [2- (p-hydroxyphenyl) ethyl] docosanamide as the reversible developer in Example 1 (A), Np-hydroxyphenyl-N ′ as the reversible developer -The same procedure as in Example 1 except that 100 parts of nonacosylurea was used, and 5 parts of n-nonyltrimethylammonium chloride was used as a decoloring accelerator instead of 5 parts of n-octadecyltrimethylammonium chloride as a decoloring accelerator. Thus, a reversible thermosensitive recording material of Comparative Example 5 was obtained.

(Comparative Example 6)
In Example 1 (A), in place of using 5 parts of n-octadecyltrimethylammonium chloride as a decoloring accelerator, 10 parts of N, N'-dioctadecylurea was used as a decoloring accelerator. Similarly, a reversible thermosensitive recording material of Comparative Example 6 was obtained.

(Comparative Example 7)
Example 1 (A) was the same as Example 1 except that 5 parts of tetra-n-butylammonium chloride was used as the color erasure accelerator instead of 5 parts of n-octadecyltrimethylammonium chloride as the color erasure accelerator. Thus, a reversible thermosensitive recording material of Comparative Example 7 was obtained.

(Test 1) Coloring test For the evaluation method of the coloring test, the reversible thermosensitive recording materials obtained in Examples 1 to 8 and Comparative Examples 1 to 7 were used as the print head (BHC4215SS manufactured by TDK Corporation, resistance value). Was printed at 13V, 15V, and 17V under conditions of a pulse width of 2 msec and a pulse period of 4.05 msec. . The color density and the background density were measured using a Macbeth densitometer RD-918.

(Test 2) Decoloring test For the evaluation method of the decoloring test, the reversible thermosensitive recording material obtained in Examples 1 to 8 and Comparative Examples 1 to 7 was used as a print head (BHC4215SS manufactured by TDK Corporation). On a sample printed at a voltage of 17 V under a condition of a pulse width of 2 msec and a pulse period of 4.05 msec using a thermal paper evaluation apparatus (resistance value: 1,004Ω) (TH-PMG manufactured by Okura Engineering Co., Ltd.) Erasing was performed with an inclination tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.) at a heat stamp temperature of 100 ° C. for 0.1 seconds and 0.5 seconds. Using the Macbeth densitometer RD-918, the density of the image area after erasure was measured.

(Test 3) Image heat-resistant storage test For the image heat-resistant storage test, the reversible thermosensitive recording materials obtained in Examples 1 to 8 and Comparative Examples 1 to 7 were used as print heads (BHC4215SS manufactured by TDK Corporation, resistance). A sample printed at a voltage of 17 V under a condition of a pulse width of 2 msec and a pulse cycle of 4.05 msec using a thermal paper evaluation apparatus (value: 1,004Ω) (TH-PMG manufactured by Okura Engineering Co., Ltd.) It was stored for 24 hours under environmental conditions of ° C. and a relative humidity of 20% RH. Using a Macbeth densitometer RD-918, the color density before and after storage was measured, and the image residual ratio was calculated by the following formula.
Image residual ratio (%) = (image density after storage−background density after storage) / (image density before storage−background density before storage) × 100

  The results of Test 1, Test 2 and Test 3 are shown in Table 1.

  As is clear from Table 1, the reversible thermosensitive recording materials of Examples 1 to 8 have high color density at low energy, excellent color development sensitivity, good decoloring characteristics, and high speed erasability. It turns out that it is excellent. It can also be seen that the heat-resistant image stability is high.

Example 9
(G) Preparation of reversible thermosensitive recording layer coating solution 3- (1-ethyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide as a dye precursor 20 parts, N-docosyl- [3- (p-hydroxyphenyl)] propionamide 100 parts as reversible developer, 5 parts n-hexadecyltrimethylammonium chloride as erasure accelerator, vanadyl 5 as photothermal conversion dye , 14,23,32-tetraphenyl-2,3-naphthalocyanine 0.1 part, polyester polyol (manufactured by DIC Corporation, trade name: Bernock 11-408, active ingredient: 70% by mass), 100 parts, methyl ethyl ketone 950 Part of the mixture was dispersed together with glass beads in a paint shaker for 5 hours to obtain a dispersion. To the dispersion thus obtained, 130 parts of an isocyanate compound (manufactured by Mitsui Chemicals, trade name: Takenate D-110N, active ingredient: 75% by mass) and 62 parts of methyl ethyl ketone are added and mixed well, and reversible thermosensitive. A recording layer coating solution was prepared.

(H) Coating of reversible thermosensitive recording layer coating liquid The reversible thermosensitive recording layer coating liquid obtained in (G) is applied to a white polyethylene terephthalate (PET) sheet having a thickness of 250 μm in a dry coating amount of 10 g / m ^2. Then, after drying at 100 ° C. for 1 minute, it was further cured by heating at 50 ° C. for 24 hours to form a reversible thermosensitive recording layer.

(I) Preparation of intermediate layer coating solution 50 parts 2,2'-methylenebis [6- (2H-benzotriazol-2-yl) -4- (2-hydroxyethyl) phenol] as a UV absorber, polyester polyol (DIC) Co., Ltd., trade name: Bernock 11-408, active ingredient 70 mass%) 100 parts and a mixture of 800 parts of methyl ethyl ketone were dispersed together with glass beads for 5 hours with a paint shaker to obtain a dispersion. To the dispersion thus obtained, 140 parts of an isocyanate compound (trade name: Takenate D-110N, active ingredient 75% by mass, manufactured by Mitsui Chemicals, Inc.) and 50 parts of methyl ethyl ketone were added and mixed well, and the intermediate layer coating solution was added. Was prepared.

(J) Application of intermediate layer coating solution On the reversible thermosensitive recording layer coating surface of the coating sheet prepared in (H), the intermediate layer coating solution obtained in (I) has a dry coating amount of 2 g / m ^2. And dried at 100 ° C. for 1 minute, and further cured by heating at 50 ° C. for 24 hours to provide an intermediate layer.

(K) Preparation of protective layer coating solution Urethane acrylate UV curable resin (manufactured by DIC Corporation, trade name: Unidic 17-813, active ingredient: 80% by mass) 12.5 parts, wet silica (Fuji Silysia Chemical) (Product name: Silicia 350) 2.0 parts and butyl acetate 10 parts were mixed. The liquid mixture thus obtained was treated with a bead mill to prepare a protective layer coating solution.

(L) Coating of the protective layer coating liquid On the intermediate layer coated surface of the coating sheet prepared in (J), the dry coating amount of the protective layer coating liquid obtained in (K) is 3 g / m ^2. And dried at 120 ° C. for 1 minute, and then cured by passing under an ultraviolet lamp with an irradiation energy of 120 W / cm at a conveying speed of 10 m / min to provide a protective layer. The reversible thermosensitive recording material of Example 9 Got.

(Example 10)
Instead of using 100 parts of N-docosyl- [3- (p-hydroxyphenyl)] propionamide as the reversible developer in Example 9 (G), N-docosyl- (p- A reversible thermosensitive recording material of Example 10 was obtained in the same manner as Example 9 except that 100 parts of hydroxyphenyl) acetamide was used.

(Example 11)
Instead of using 100 parts of N-docosyl- [3- (p-hydroxyphenyl)] propionamide as the reversible developer in Example 9 (G), N-triacontyl- [3- (P-hydroxyphenyl)] propionamide 100 parts, instead of using 5 parts of n-hexadecyltrimethylammonium chloride as a decoloring accelerator, 7 parts of n-docosyltrimethylammonium bromide as a decoloring accelerator A reversible thermosensitive recording material of Example 11 was obtained in the same manner as Example 9 except for the above.

(Example 12)
In Example 9 (G), instead of using 100 parts of N-docosyl- [3- (p-hydroxyphenyl)] propionamide as the reversible developer, N- [2- (p A reversible thermosensitive recording material of Example 12 was obtained in the same manner as Example 9 except that 90 parts of -hydroxyphenyl) ethyl] -N'-nonacosylurea was used.

(Example 13)
In Example 9 (G), instead of using 100 parts of N-docosyl- [3- (p-hydroxyphenyl)] propionamide as the reversible developer, N- [2- (p N-hexadecyltrimethylammonium tetrafluoroborate 5 as a decoloring accelerator instead of using 100 parts of -hydroxyphenyl) ethyl] -N'-henicosyl and 5 parts of n-hexadecyltrimethylammonium chloride as the decoloring accelerator A reversible thermosensitive recording material of Example 13 was obtained in the same manner as in Example 9, except that the parts were used.

(Comparative Example 8)
In Example 9 (G), a reversible thermosensitive recording material of Comparative Example 8 was obtained in the same manner as Example 9 except that 5 parts of n-hexadecyltrimethylammonium chloride was not added as a decoloring accelerator.

(Comparative Example 9)
In Example 9 (G), instead of using 100 parts of N-docosyl- [3- (p-hydroxyphenyl)] propionamide as the reversible developer, N- [2- (p A reversible thermosensitive recording material of Comparative Example 9 was obtained in the same manner as in Example 9, except that 100 parts of -hydroxyphenyl) ethyl] nonadecanamide were used.

(Comparative Example 10)
In Example 9 (G), instead of using 100 parts of N-docosyl- [3- (p-hydroxyphenyl)] propionamide as the reversible developer, N- [3- (p Reversible thermosensitive recording material of Comparative Example 10 was obtained in the same manner as in Example 9 except that 100 parts of -hydroxyphenyl) propiono] -N'-docosanohydrazide was used.

(Comparative Example 11)
Instead of using 100 parts of N-docosyl- [3- (p-hydroxyphenyl)] propionamide as the reversible developer in Example 9 (G), Np-hydroxyphenyl- Example 9 except that 100 parts of N'-tricosylurea was used and 5 parts of n-dodecyltrimethylammonium chloride was used as the color erasure accelerator instead of 5 parts of n-hexadecyltrimethylammonium chloride as the color erasure accelerator. In the same manner, a reversible thermosensitive recording material of Comparative Example 11 was obtained.

(Test 4) Laser color development test For the evaluation method of the color development test, the reversible thermosensitive recording materials obtained in Examples 9 to 13 and Comparative Examples 8 to 11 were used as LD laser markers (manufactured by Sunkus Co., Ltd., commercial products). Name: LP-D20), printing was performed under the conditions of scanning speeds of 1,000 mm / sec, 1,200 mm / sec, and 1,400 mm / sec at an output of 100%. The color density and the background density were measured using a Macbeth densitometer RD-918.

(Test 5) Warm air erasure test For the evaluation method of the decoloration test, the reversible thermosensitive recording materials obtained in Examples 9 to 13 and Comparative Examples 8 to 11 were used as LD laser markers (manufactured by Sunkus Co., Ltd.). , Product name: LP-D20), printing is performed at an output of 100% and a scanning speed of 1,000 mm / sec to produce a print sample. This print sample was placed 3 cm away from the heat gun, and erased by irradiating warm air with a temperature of 180 ° C. and an air volume of 0.2 m ³ / min for 3 seconds and 10 seconds. Using the Macbeth densitometer RD-918, the density of the image area after erasure was measured.

  The results of Test 4 and Test 5 are shown in Table 2.

  As is apparent from Table 2, it can be seen that the reversible thermosensitive recording materials of Examples 9 to 13 have high color density and excellent color sensitivity even at a high scanning speed in laser printing. In addition, it can be seen that erasing with hot air can be performed even in a short time and is excellent in high-speed erasability.

  From the above results, as a reversible developer, a compound having an aliphatic hydrocarbon group having 20 or more carbon atoms, a specific hydrogen bonding group, and a spacer group having a specific carbon number is used, and further, as a decoloring accelerator, The reversible thermosensitive recording material of the present invention using a specific quaternary ammonium salt compound is capable of forming and erasing an image having a clear contrast, has good color development sensitivity, and is excellent in high-speed erasability. It turns out that it is expensive.

Claims (1)

Contains a normally colorless or light-colored dye precursor on a support and a reversible developer that forms a relatively colored state and a decolored state due to differences in heating temperature and / or cooling rate after heating. The reversible thermosensitive recording material contains a phenol compound represented by the following general formula (1) as the reversible developer, and a quaternary represented by the following general formula (2) as a decoloring accelerator. A reversible thermosensitive recording material containing an ammonium salt compound.

(In General Formula (1), m represents an integer of 1 to 3, n represents an integer of 20 or more, and X represents an amide group or a urea group.)

(In the general formula (2), R ₁ , R ₂ and R ₃ are synonymous, and are saturated or unsaturated hydrocarbon groups having 1 to 24 carbon layers which may be the same or different from each other, Two of these hydrocarbon groups may be bonded to each other to form a ring, R ₄ represents a saturated or unsaturated hydrocarbon group having 6 to 24 carbon atoms, and p represents 1 or 2. A Represents an anion, and q and r represent an integer for adjusting the charge in the molecule to 0.)