Color developer and thermosensitive recording material

Abstract

Provided is a color developer capable of realizing a thermosensitive recording material that has excellent color-generating sensitivity and heat resistance of unprinted parts. Also provided is a thermosensitive recording material obtained using the color developer.　The color developer contains a compound represented by formula (1) (in formula (1), any one of R1, R2, and R3 is a hydrogen atom). The thermosensitive recording material contains the color developer.

Description

Color developer and thermal recording material

[0001] The present invention relates to a color developer capable of providing a heat-sensitive recording material excellent in color development sensitivity and heat resistance of non-printed areas, and to a heat-sensitive recording material obtained by using the color developer.

[0002] In general, heat-sensitive recording materials having a heat-sensitive recording layer mainly composed of a colorless or pale-colored basic (electron-donating) leuco dye (hereinafter sometimes abbreviated as "dye") and an electron-accepting developer (hereinafter sometimes abbreviated as "developer") that reacts with the dye to develop color when heated have been widely put to practical use.

[0003] Many of the compounds used as such color developers are compounds that mainly contain a phenol structure, such as 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), bis(4-hydroxyphenyl)sulfone (bisphenol S), etc. However, due to concerns about environmental impact, studies are also being conducted to use compounds that do not have a phenol structure as color developers.

[0004] As a compound not having a phenol structure, for example, a color developer having a sulfonylurea structure compound having a p-toluenesulfonyloxyphenyl moiety is useful, but since the sulfonylurea skeleton is used, there are concerns about safety to the human body, and color developers utilizing safer raw materials are desired. For example, Patent Documents 1 to 6 disclose methods using ascorbic acid or an ascorbic acid derivative as a color developer.

[0005] JP 4-270683 JP 2-117890 JP 63-256488 JP 2018-103469 JP 63-179787 JP 60-101171

[0006] According to the investigations of the present inventors, when ascorbic acid or an ascorbic acid derivative shown in Patent Documents 1 to 6 is used as a color developer, it is not always possible to obtain a thermal recording material that satisfies both sufficient color development sensitivity and heat resistance of non-printed areas. That is, an object of the present invention is to provide a color developer that can provide a thermal recording material that is even more excellent in terms of color development sensitivity and heat resistance of non-printed areas, and a thermal recording material obtained by using the color developer.

[0007] As a result of extensive investigations, the present inventors have found that the above-mentioned problems can be solved by using an ascorbic acid derivative, which is a compound represented by formula (1), as a color developer.

[0008] <1> A color developer containing a compound represented by the following formula (1): In formula (1), any one of R1, R2, and R3 is a hydrogen atom, and (i) when R1 is a hydrogen atom, R2 and R3 may be the same or different independently from each other, R2 is any one selected from the group consisting of an aliphatic hydrocarbon group having 1 to 30 carbon atoms which may have a substituent, an alkylcarbonyl group having 2 to 31 carbon atoms which may have a substituent, an alkylaminocarbonyl group having 2 to 31 carbon atoms which may have a substituent, an alkylsulfonylaminocarbonyl group having 2 to 31 carbon atoms which may have a substituent, a phenyl group which may have a substituent, a naphthyl group which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, a benzoyl group which may have a substituent, a naphthoyl group which may have a substituent, an arylalkyl group having 7 to 48 carbon atoms which may have a substituent, an arylalkylcarbonyl group having 8 to 49 carbon atoms which may have a substituent, an arylalkylaminocarbonyl group having 8 to 49 carbon atoms which may have a substituent, and an arylalkylsulfonylaminocarbonyl group having 8 to 49 carbon atoms which may have a substituent, R3 represents any one selected from the group consisting of an alkylaminocarbonyl group having 2 to 31 carbon atoms which may have a substituent, an alkylsulfonylaminocarbonyl group having 2 to 31 carbon atoms which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, an arylalkylaminocarbonyl group having 8 to 49 carbon atoms which may have a substituent, and an arylalkylsulfonylaminocarbonyl group having 8 to 49 carbon atoms which may have a substituent, (ii) when R2 is a hydrogen atom, R1 and R3 may be the same or independently different,R1 and R3 each represent any one selected from the group consisting of an aliphatic hydrocarbon group having 1 to 30 carbon atoms which may have a substituent, an alkylcarbonyl group having 2 to 31 carbon atoms which may have a substituent, an alkylaminocarbonyl group having 2 to 31 carbon atoms which may have a substituent, an alkylsulfonylaminocarbonyl group having 2 to 31 carbon atoms which may have a substituent, a phenyl group which may have a substituent, a naphthyl group which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, a benzoyl group which may have a substituent, a naphthoyl group which may have a substituent, an arylalkyl group having 7 to 48 carbon atoms which may have a substituent, an arylalkylcarbonyl group having 8 to 49 carbon atoms which may have a substituent, an arylalkylaminocarbonyl group having 8 to 49 carbon atoms which may have a substituent, and an arylalkylsulfonylaminocarbonyl group having 8 to 49 carbon atoms which may have a substituent, (iii) when R3 is a hydrogen atom, R1 and R2 may be the same or independently different from each other, R1 and R2 each represent any one selected from the group consisting of an aliphatic hydrocarbon group having 7 to 30 carbon atoms, which may have a substituent, an alkylaminocarbonyl group having 2 to 31 carbon atoms, which may have a substituent, an alkylsulfonylaminocarbonyl group having 2 to 31 carbon atoms, which may have a substituent, a phenyl group, which may have a substituent, a naphthyl group, which may have a substituent, a phenylaminocarbonyl group, which may have a substituent, a phenylsulfonylaminocarbonyl group, which may have a substituent, a benzoyl group, a naphthoyl group, which may have a substituent, an arylalkyl group having 7 to 48 carbon atoms, which may have a substituent, an arylalkylcarbonyl group having 8 to 49 carbon atoms, which may have a substituent, an arylalkylaminocarbonyl group having 8 to 49 carbon atoms, which may have a substituent, and an arylalkylsulfonylaminocarbonyl group having 8 to 49 carbon atoms, which may have a substituent. <2> The color developer according to <1>, wherein R1 or R2 in formula (1) is a hydrogen atom. <3> The color developer according to <2>, wherein R1 in formula (1) is a hydrogen atom.<4> The color developer according to <3>, wherein in formula (1), R2 is any one selected from the group consisting of an alkylcarbonyl group having 2 to 18 carbon atoms which may have a substituent, an alkylaminocarbonyl group having 2 to 18 carbon atoms which may have a substituent, an alkylsulfonylaminocarbonyl group having 2 to 18 carbon atoms which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, a benzoyl group which may have a substituent, and a naphthoyl group which may have a substituent; and R3 is any one selected from the group consisting of a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, an arylalkylaminocarbonyl group having 8 to 24 carbon atoms which may have a substituent, and an arylalkylsulfonylaminocarbonyl group having 8 to 24 carbon atoms which may have a substituent. <5> The color developer according to <3>, wherein in formula (1), R2 is any one selected from the group consisting of an alkylcarbonyl group having 6 to 18 carbon atoms which may have a substituent, an alkylaminocarbonyl group having 6 to 18 carbon atoms which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, a benzoyl group which may have a substituent, and a naphthoyl group which may have a substituent, and R3 is a phenylaminocarbonyl group which may have a substituent or a phenylsulfonylaminocarbonyl group which may have a substituent. <6> The color developer according to any one of <1> to <5>, wherein the compound represented by formula (1) is at least one of a compound represented by the following formula (1-1) or a compound represented by the following formula (1-2): (In formula (1-1), R1 to R3 have the same meanings as R1 to R3 in formula (1), respectively.) (In formula (1-2), R1 to R3 have the same meanings as R1 to R3 in formula (1), respectively.) <7> A thermosensitive recording material having a support and a thermosensitive recording layer provided on the support, wherein the thermosensitive recording layer contains the developer described in any one of <1> to <6> above. <8> The thermosensitive recording material described in <7> above, wherein the thermosensitive recording layer contains a leuco dye. <9> The thermosensitive recording material described in <7> or <8> above, wherein the thermosensitive recording layer contains a sensitizer. <10> The thermosensitive recording material described in any one of <7> to <9> above, wherein the thermosensitive recording layer contains a stabilizer.

[0009] According to the present invention, there are provided a color developer capable of providing a heat-sensitive recording material excellent in color development sensitivity and heat resistance of non-printed areas, and a heat-sensitive recording material obtained by using said color developer.

[0010] The present invention will be described in detail below, but the present invention is not limited to the following description and can be modified as desired within the scope of the present invention. In the present invention, when a term "to" is used with a numerical value or a physical property value between the two, the term "to" is used to include the values ​​before and after the term. In the present disclosure, the "substituent" is not particularly limited, and may be, for example, a group selected from a hydroxy group, a carboxy group, a halogen atom, a nitro group, a cyano group, an amino group, an aliphatic hydrocarbon group, an alkoxy group, an alkenyloxy group, an aryl group, an aryloxy group, and an arylalkyl group, or a combination thereof. Examples of halogen atoms include fluorine, chlorine, bromine, iodine, astatine, and tennessine. Preferred are fluorine, chlorine, bromine, and iodine, more preferably fluorine, chlorine, and bromine, even more preferably fluorine and chlorine, and particularly preferably fluorine. Examples of aliphatic hydrocarbon groups include alkyl groups, alkenyl groups, and alkynyl groups, and preferred are alkyl groups and alkenyl groups. The number of carbon atoms in the aliphatic hydrocarbon group is not particularly limited, but is typically 1 to 8. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an i-propyl group, a butyl group, an i-butyl group, a t-butyl group, a pentyl group, an i-pentyl group, a hexyl group, a cyclohexyl group, a heptyl group, an octyl group, and a 2-ethylhexyl group, and preferably a methyl group or an ethyl group. The number of carbon atoms in the alkenyl group is not particularly limited, but is usually 2 to 4. Examples of the alkenyl group include a vinyl group, an allyl group, a propenyl group, and a butenyl group, and preferably a vinyl group or an allyl group. The number of carbon atoms in the alkynyl group is not particularly limited, but is usually 2 to 4. Examples of the alkynyl group include an ethynyl group and a prop-2-yn-1-yl group. The number of carbon atoms in the alkoxy group is not particularly limited, but is usually 1 to 8. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, an i-propoxy group, a butoxy group, an i-butoxy group, a t-butoxy group, a pentyloxy group, an i-pentyloxy group, a hexyloxy group, a cyclohexyloxy group, a heptyloxy group, an octyloxy group, and a 2-ethylhexyloxy group, and preferably a methoxy group or an ethoxy group.The number of carbon atoms in the alkenyloxy group is not particularly limited, but is typically 2 to 4. Examples include vinyloxy, allyloxy, 1-propenyloxy, and 2-propenyloxy groups, with vinyloxy and allyloxy groups being preferred. The number of carbon atoms in the aryl group is not particularly limited, but is typically 6 to 18. Examples of aryl groups include phenyl, naphthyl, and anthracenyl groups, with phenyl and naphthyl being preferred. The number of carbon atoms in the aryloxy group is not particularly limited, but is typically 6 to 18. Examples of aryloxy groups include phenyloxy, naphthyloxy, and anthracenyloxy groups, with phenyloxy being preferred. The number of carbon atoms in the arylalkyl group is not particularly limited, but is typically 7 to 20. The arylalkyl group is a group in which one hydrogen atom is removed from the alkyl group described above and the aryl group described above is bonded to it. Examples of the arylalkyl group include a benzyl group, a phenylethyl group, a phenylpropyl group, a naphthylmethyl group, a naphthylethyl group, a naphthylpropyl group, an anthracenylmethyl group, and an anthracenylethyl group, and preferred are a benzyl group, a phenylethyl group, a naphthylmethyl group, and an anthracenylmethyl group.

[0011] The phrase "may have a substituent" means that the group may have a substituent, but preferably does not have a substituent.

[0012] [Color Developer] The color developer of the present invention contains a compound represented by the following formula (1): In the present invention, the compound represented by formula (1) may be referred to as "compound (I)."

[0013]

[0014] The color developer of the present invention exhibits the remarkable effect of being excellent in color development sensitivity and heat resistance of non-printed areas. The reason why the present invention exhibits such excellent effects is presumably as follows. First, it is believed that the introduction of a highly hydrophobic functional group into ascorbic acid increases compatibility with the leuco dye, making it easier to react with the leuco dye, thereby improving color development sensitivity.

[0015] Furthermore, the compound represented by formula (1) contained in the color developer of the present invention has a higher melting point due to the introduction of an N-H moiety into the 2-O moiety of ascorbic acid, and is therefore less likely to melt and develop color even when heat of, for example, 80°C is applied to the non-printed areas, which is thought to further improve the heat resistance of the non-printed areas.

[0016] [R1, R2, R3 in Formula (1)] In formula (1), any one of R1, R2, and R3 is a hydrogen atom.

[0017] (i) In formula (1), when R1 is a hydrogen atom, R2 and R3 may be the same or different independently.

[0018] In formula (1), when R1 is a hydrogen atom, R2 is any one selected from the group consisting of an aliphatic hydrocarbon group of 1 to 30 carbon atoms which may have a substituent, an alkylcarbonyl group of 2 to 31 carbon atoms which may have a substituent, an alkylaminocarbonyl group of 2 to 31 carbon atoms which may have a substituent, an alkylsulfonylaminocarbonyl group of 2 to 31 carbon atoms which may have a substituent, a phenyl group which may have a substituent, a naphthyl group which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, a benzoyl group which may have a substituent, a naphthoyl group which may have a substituent, an arylalkyl group of 7 to 48 carbon atoms which may have a substituent, an arylalkylcarbonyl group of 8 to 49 carbon atoms which may have a substituent, an arylalkylaminocarbonyl group of 8 to 49 carbon atoms which may have a substituent, and an arylalkylsulfonylaminocarbonyl group of 8 to 49 carbon atoms which may have a substituent.From the viewpoint of improving the compatibility with the leuco dye to increase the color development sensitivity, and from the viewpoint of suppressing the thermal motion of the molecules to easily improve the storage stability of the background, the alkyl group is preferably any one selected from the group consisting of an alkylcarbonyl group having 2 to 18 carbon atoms which may have a substituent, an alkylaminocarbonyl group having 2 to 18 carbon atoms which may have a substituent, an alkylsulfonylaminocarbonyl group having 2 to 18 carbon atoms which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, a benzoyl group which may have a substituent, and a naphthoyl group which may have a substituent, and the alkylcarbonyl group is preferably any one selected from the group consisting of an alkylcarbonyl group having 6 to 18 carbon atoms which may have a substituent, an alkylaminocarbonyl group having 2 to 18 carbon atoms which may have a substituent, an alkylsulfonylaminocarbonyl group having 2 to 18 carbon atoms which may have a substituent, an alkylaminocarbonyl group having 6 ...

[0044] The alkylaminocarbonyl group may have a substituent and is more preferably any one selected from the group consisting of an alkylaminocarbonyl group having 6 to 18 carbon atoms which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, a benzoyl group which may have a substituent, and a naphthoyl group which may have a substituent, and is particularly preferably any one selected from the group consisting of an alkylcarbonyl group having 2 to 18 carbon atoms which may have a substituent, an alkylaminocarbonyl group having 2 to 18 carbon atoms which may have a substituent, and an alkylsulfonylaminocarbonyl group having 2 to 18 carbon atoms which may have a substituent, and is most preferably an alkylcarbonyl group having 6 to 18 carbon atoms which may have a substituent.

[0019] In formula (1), when R1 is a hydrogen atom, R3 is any one selected from the group consisting of an alkylaminocarbonyl group having 2 to 31 carbon atoms which may have a substituent, an alkylsulfonylaminocarbonyl group having 2 to 31 carbon atoms which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, an arylalkylaminocarbonyl group having 8 to 49 carbon atoms which may have a substituent, and an arylalkylsulfonylaminocarbonyl group having 8 to 49 carbon atoms which may have a substituent. From the viewpoint of improving the compatibility with the leuco dye to increase the color development sensitivity, and from the viewpoint of suppressing the thermal motion of molecules to easily improve the storage stability of the background portion, the alkyl group is preferably any one selected from the group consisting of an optionally substituted phenylaminocarbonyl group, an optionally substituted phenylsulfonylaminocarbonyl group, an optionally substituted arylalkylaminocarbonyl group having 8 to 24 carbon atoms, and an optionally substituted arylalkylsulfonylaminocarbonyl group having 8 to 24 carbon atoms, more preferably an optionally substituted phenylaminocarbonyl group or an optionally substituted phenylsulfonylaminocarbonyl group, and particularly preferably an optionally substituted phenylaminocarbonyl group.

[0020] (ii) When R2 in formula (1) is a hydrogen atom, R1 and R3 may be the same or different independently.

[0021] In formula (1), when R2 is a hydrogen atom, R1 is any one selected from the group consisting of an aliphatic hydrocarbon group of 1 to 30 carbon atoms which may have a substituent, an alkylcarbonyl group of 2 to 31 carbon atoms which may have a substituent, an alkylaminocarbonyl group of 2 to 31 carbon atoms which may have a substituent, an alkylsulfonylaminocarbonyl group of 2 to 31 carbon atoms which may have a substituent, a phenyl group which may have a substituent, a naphthyl group which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, a benzoyl group which may have a substituent, a naphthoyl group which may have a substituent, an arylalkyl group of 7 to 48 carbon atoms which may have a substituent, an arylalkylcarbonyl group of 8 to 49 carbon atoms which may have a substituent, an arylalkylaminocarbonyl group of 8 to 49 carbon atoms which may have a substituent, and an arylalkylsulfonylaminocarbonyl group of 8 to 49 carbon atoms which may have a substituent. From the viewpoint of improving the compatibility with the leuco dye to increase the color development sensitivity, and from the viewpoint of suppressing the thermal motion of molecules to easily improve the storage stability of the background portion, the alkyl group is preferably any one selected from the group consisting of an alkylcarbonyl group having 2 to 18 carbon atoms which may have a substituent, an alkylaminocarbonyl group having 2 to 18 carbon atoms which may have a substituent, an alkylsulfonylaminocarbonyl group having 2 to 18 carbon atoms which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, a benzoyl group which may have a substituent, and a naphthoyl group which may have a substituent, and more preferably any one selected from the group consisting of an alkylcarbonyl group having 6 to 18 carbon atoms which may have a substituent, an alkylaminocarbonyl group having 6 to 18 carbon atoms which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, a benzoyl group, and a naphthoyl group which may have a substituent.

[0022] In formula (1), when R2 is a hydrogen atom, R3 is any one selected from the group consisting of an aliphatic hydrocarbon group of 1 to 30 carbon atoms which may have a substituent, an alkylcarbonyl group of 2 to 31 carbon atoms which may have a substituent, an alkylaminocarbonyl group of 2 to 31 carbon atoms which may have a substituent, an alkylsulfonylaminocarbonyl group of 2 to 31 carbon atoms which may have a substituent, a phenyl group which may have a substituent, a naphthyl group which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, a benzoyl group which may have a substituent, a naphthoyl group which may have a substituent, an arylalkyl group of 7 to 48 carbon atoms which may have a substituent, an arylalkylcarbonyl group of 8 to 49 carbon atoms which may have a substituent, an arylalkylaminocarbonyl group of 8 to 49 carbon atoms which may have a substituent, and an arylalkylsulfonylaminocarbonyl group of 8 to 49 carbon atoms which may have a substituent. From the viewpoint of improving the compatibility with the leuco dye to increase the color development sensitivity, and from the viewpoint of suppressing the thermal motion of molecules to easily improve the storage stability of the background portion, the group consisting of an optionally substituted phenylaminocarbonyl group, an optionally substituted phenylsulfonylaminocarbonyl group, an optionally substituted arylalkylaminocarbonyl group having 8 to 24 carbon atoms, and an optionally substituted arylalkylsulfonylaminocarbonyl group having 8 to 24 carbon atoms is preferred, and an optionally substituted phenylaminocarbonyl group or an optionally substituted phenylsulfonylaminocarbonyl group is more preferred.

[0023] (iii) When R3 in formula (1) is a hydrogen atom, R1 and R2 may be the same or different independently.

[0024] In formula (1), when R3 is a hydrogen atom, R1 is any one selected from the group consisting of an aliphatic hydrocarbon group of 7 to 30 carbon atoms which may have a substituent, an alkylaminocarbonyl group of 2 to 31 carbon atoms which may have a substituent, an alkylsulfonylaminocarbonyl group of 2 to 31 carbon atoms which may have a substituent, a phenyl group which may have a substituent, a naphthyl group which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, a benzoyl group which may have a substituent, a naphthoyl group which may have a substituent, an arylalkyl group of 7 to 48 carbon atoms which may have a substituent, an arylalkylcarbonyl group of 8 to 49 carbon atoms which may have a substituent, an arylalkylaminocarbonyl group of 8 to 49 carbon atoms which may have a substituent, and an arylalkylsulfonylaminocarbonyl group of 8 to 49 carbon atoms which may have a substituent. From the viewpoint of improving the compatibility with the leuco dye to enhance color development sensitivity, and of suppressing thermal motion of molecules to easily improve the storage stability of the background, the alkylaminocarbonyl group is preferably any one selected from the group consisting of an alkylaminocarbonyl group having 2 to 18 carbon atoms which may have a substituent, an alkylsulfonylaminocarbonyl group having 2 to 18 carbon atoms which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, a benzoyl group, a naphthoyl group which may have a substituent, an arylalkylcarbonyl group having 8 to 24 carbon atoms which may have a substituent, an arylalkylaminocarbonyl group having 8 to 24 carbon atoms which may have a substituent, and an arylalkylsulfonylaminocarbonyl group having 8 to 24 carbon atoms which may have a substituent, and more preferably any one selected from the group consisting of an alkylaminocarbonyl group having 6 to 18 carbon atoms which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, a benzoyl group, and a naphthoyl group which may have a substituent.

[0025] In formula (1), when R3 is a hydrogen atom, R2 is any one selected from the group consisting of an aliphatic hydrocarbon group of 7 to 30 carbon atoms which may have a substituent, an alkylaminocarbonyl group of 2 to 31 carbon atoms which may have a substituent, an alkylsulfonylaminocarbonyl group of 2 to 31 carbon atoms which may have a substituent, a phenyl group which may have a substituent, a naphthyl group which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, a benzoyl group which may have a substituent, a naphthoyl group which may have a substituent, an arylalkyl group of 7 to 48 carbon atoms which may have a substituent, an arylalkylcarbonyl group of 8 to 49 carbon atoms which may have a substituent, an arylalkylaminocarbonyl group of 8 to 49 carbon atoms which may have a substituent, and an arylalkylsulfonylaminocarbonyl group of 8 to 49 carbon atoms which may have a substituent. From the viewpoint of improving the compatibility with the leuco dye to enhance color development sensitivity, and of suppressing thermal motion of molecules to easily improve the storage stability of the background, the alkylaminocarbonyl group is preferably any one selected from the group consisting of an alkylaminocarbonyl group having 2 to 18 carbon atoms which may have a substituent, an alkylsulfonylaminocarbonyl group having 2 to 18 carbon atoms which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, a benzoyl group, a naphthoyl group which may have a substituent, an arylalkylcarbonyl group having 8 to 24 carbon atoms which may have a substituent, an arylalkylaminocarbonyl group having 8 to 24 carbon atoms which may have a substituent, and an arylalkylsulfonylaminocarbonyl group having 8 to 24 carbon atoms which may have a substituent, and more preferably any one selected from the group consisting of an alkylaminocarbonyl group having 6 to 18 carbon atoms which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, a benzoyl group, and a naphthoyl group which may have a substituent.

[0026] In an embodiment in which the aliphatic hydrocarbon group having 1 to 30 carbon atoms and which may have a substituent does not have a substituent, examples thereof include an alkyl group, an alkenyl group, and an alkynyl group, preferably an alkyl group or an alkenyl group, and more preferably an alkyl group. The aliphatic hydrocarbon group may be linear, branched, or cyclic. From the viewpoint of improving compatibility with the leuco dye to enhance color development sensitivity, and from the viewpoint of suppressing thermal motion of molecules and facilitating improved storage stability of the background, the number of carbon atoms in the aliphatic hydrocarbon group having 1 to 30 carbon atoms and which may have a substituent is preferably 2 to 18, more preferably 4 to 18, and even more preferably 6 to 18. In the case of an alkenyl group or alkynyl group, the number of carbon atoms is 2 or more.

[0027] Specific examples of the aliphatic hydrocarbon group having 1 to 30 carbon atoms include, for example, a methyl group, an ethyl group, a propyl group, an i-propyl group, a butyl group, an i-butyl group, a t-butyl group, a pentyl group, an i-pentyl group, a hexyl group, a cyclohexyl group, a heptyl group, an octyl group, a 2-ethylhexyl group, a nonyl group, a decyl group, a dodecyl group, a tetradecyl group, a palmityl group, a stearyl group, a behenyl group, a vinyl group, an allyl group, a propenyl group, a butenyl group, an ethynyl group, and a prop-2-yn-1-yl group. Among these, ethyl group, propyl group, i-propyl group, butyl group, i-butyl group, t-butyl group, pentyl group, i-pentyl group, hexyl group, cyclohexyl group, heptyl group, octyl group, 2-ethylhexyl group, palmityl group, stearyl group, vinyl group, allyl group, and propenyl group are preferred, butyl group, t-butyl group, pentyl group, hexyl group, cyclohexyl group, octyl group, 2-ethylhexyl group, decyl group, dodecyl group, palmityl group, and stearyl group are more preferred, and hexyl group, cyclohexyl group, octyl group, 2-ethylhexyl group, decyl group, dodecyl group, palmityl group, and stearyl group are even more preferred.

[0028] In an embodiment in which the aliphatic hydrocarbon group having 7 to 30 carbon atoms and which may have a substituent is unsubstituted, examples thereof include an alkyl group, an alkenyl group, and an alkynyl group, preferably an alkyl group or an alkenyl group, and more preferably an alkyl group. The aliphatic hydrocarbon group may be linear, branched, or cyclic. From the viewpoint of improving compatibility with the leuco dye to increase color development sensitivity, and from the viewpoint of suppressing thermal motion of molecules and facilitating improved storage stability of the background portion, the carbon number of the aliphatic hydrocarbon group having 7 to 30 carbon atoms and which may have a substituent is preferably 7 to 18.

[0029] Specific examples of the aliphatic hydrocarbon group having 7 to 30 carbon atoms include heptyl, octyl, 2-ethylhexyl, nonyl, decyl, dodecyl, tetradecyl, palmityl, stearyl, behenyl, etc. Among these, heptyl, octyl, 2-ethylhexyl, palmityl, and stearyl are preferred, octyl, 2-ethylhexyl, decyl, dodecyl, palmityl, and stearyl are more preferred, and octyl, 2-ethylhexyl, decyl, dodecyl, palmityl, and stearyl are even more preferred.

[0030] Examples of the alkylcarbonyl group having 2 to 31 carbon atoms which may have a substituent include the following in an embodiment in which the alkylcarbonyl group does not have a substituent: Among these, from the viewpoint of improving compatibility with the leuco dye to increase color development sensitivity, and from the viewpoint of suppressing thermal motion of molecules to easily improve storage stability of the background portion, an alkylcarbonyl group having 2 to 18 carbon atoms is preferred, and an alkylcarbonyl group having 6 to 18 carbon atoms is more preferred.

[0031] Specific examples of alkylcarbonyl groups having 2 to 31 carbon atoms include, for example, methylcarbonyl group, ethylcarbonyl group, propylcarbonyl group, i-propylcarbonyl group, butylcarbonyl group, i-butylcarbonyl group, t-butylcarbonyl group, pentylcarbonyl group, i-pentylcarbonyl group, hexylcarbonyl group, cyclohexylcarbonyl group, heptylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, nonylcarbonyl group, decylcarbonyl group, dodecylcarbonyl group, tetradecylcarbonyl group, palmitylcarbonyl group, stearylcarbonyl group, and behenylcarbonyl group. Among these, any one of an ethylcarbonyl group, a propylcarbonyl group, an i-propylcarbonyl group, a butylcarbonyl group, an i-butylcarbonyl group, a t-butylcarbonyl group, a pentylcarbonyl group, an i-pentylcarbonyl group, a hexylcarbonyl group, a cyclohexylcarbonyl group, a heptylcarbonyl group, an octylcarbonyl group, a 2-ethylhexylcarbonyl group, a palmitylcarbonyl group, and a stearylcarbonyl group is preferred, and any one of a hexylcarbonyl group, a cyclohexylcarbonyl group, an octylcarbonyl group, a 2-ethylhexylcarbonyl group, a decylcarbonyl group, a dodecylcarbonyl group, a palmitylcarbonyl group, and a stearylcarbonyl group is more preferred.

[0032] Examples of the alkylaminocarbonyl group having 2 to 31 carbon atoms which may have a substituent include the following in an embodiment in which the alkylaminocarbonyl group does not have a substituent: Among these, from the viewpoint of improving compatibility with the leuco dye to increase color development sensitivity, and from the viewpoint of suppressing thermal motion of molecules to easily improve storage stability of the background portion, alkylaminocarbonyl groups having 2 to 18 carbon atoms are preferred, and alkylaminocarbonyl groups having 6 to 18 carbon atoms are more preferred.

[0033] Specific examples of alkylaminocarbonyl groups having 2 to 31 carbon atoms include, for example, methylaminocarbonyl group, ethylaminocarbonyl group, propylaminocarbonyl group, i-propylaminocarbonyl group, butylaminocarbonyl group, i-butylaminocarbonyl group, t-butylaminocarbonyl group, pentylaminocarbonyl group, i-pentylaminocarbonyl group, hexylaminocarbonyl group, cyclohexylaminocarbonyl group, heptylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, nonylaminocarbonyl group, decylaminocarbonyl group, dodecylaminocarbonyl group, tetradecylaminocarbonyl group, palmitylaminocarbonyl group, stearylaminocarbonyl group, and behenylaminocarbonyl group. Among these, any one of an ethylaminocarbonyl group, a propylaminocarbonyl group, an i-propylaminocarbonyl group, a butylaminocarbonyl group, an i-butylaminocarbonyl group, a t-butylaminocarbonyl group, a pentylaminocarbonyl group, an i-pentylaminocarbonyl group, a hexylaminocarbonyl group, a cyclohexylaminocarbonyl group, a heptylaminocarbonyl group, an octylaminocarbonyl group, a 2-ethylhexylaminocarbonyl group, a palmitylaminocarbonyl group, and a stearylaminocarbonyl group is preferred, and any one of a hexylaminocarbonyl group, a cyclohexylaminocarbonyl group, an octylaminocarbonyl group, a 2-ethylhexylaminocarbonyl group, a decylaminocarbonyl group, a dodecylaminocarbonyl group, a palmitylaminocarbonyl group, and a stearylaminocarbonyl group is more preferred.

[0034] Examples of the alkylsulfonylaminocarbonyl group having 2 to 31 carbon atoms which may have a substituent but which does not have a substituent include the following: Among these, an alkylaminocarbonyl group having 2 to 18 carbon atoms is preferred from the viewpoint of improving compatibility with the leuco dye to increase color development sensitivity, and from the viewpoint of suppressing thermal motion of molecules to easily improve storage stability of the background portion.

[0035] Specific examples of alkylsulfonylaminocarbonyl groups having 2 to 31 carbon atoms include, for example, a (methylsulfonyl)aminocarbonyl group, an (ethylsulfonyl)aminocarbonyl group, a (propylsulfonyl)aminocarbonyl group, an (i-propylsulfonyl)aminocarbonyl group, a (butylsulfonyl)aminocarbonyl group, an (i-butylsulfonyl)aminocarbonyl group, a (t-butylsulfonyl)aminocarbonyl group, a (pentylsulfonyl)aminocarbonyl group, an (i-pentylsulfonyl)aminocarbonyl group, and a (hexylsulfonyl)aminocarbonyl group. Examples of such groups include a (cyclohexylsulfonyl)aminocarbonyl group, a (heptylsulfonyl)aminocarbonyl group, an (octylsulfonyl)aminocarbonyl group, a (2-ethylhexylsulfonyl)aminocarbonyl group, a (nonylsulfonyl)aminocarbonyl group, a (decylsulfonyl)aminocarbonyl group, a (dodecylsulfonyl)aminocarbonyl group, a (tetradecylsulfonyl)aminocarbonyl group, a (palmitylsulfonyl)aminocarbonyl group, a (stearylsulfonyl)aminocarbonyl group, and a (behenylsulfonyl)aminocarbonyl group. Among these, any one of an (ethylsulfonyl)aminocarbonyl group, a (propylsulfonyl)aminocarbonyl group, an (i-propylsulfonyl)aminocarbonyl group, a (butylsulfonyl)aminocarbonyl group, an (i-butylsulfonyl)aminocarbonyl group, a (t-butylsulfonyl)aminocarbonyl group, a (pentylsulfonyl)aminocarbonyl group, an (i-pentylsulfonyl)aminocarbonyl group, a (hexylsulfonyl)aminocarbonyl group, a (cyclohexylsulfonyl)aminocarbonyl group, a (heptylsulfonyl)aminocarbonyl group, an (octylsulfonyl)aminocarbonyl group, a (2-ethylhexylsulfonyl)aminocarbonyl group, a (palmitylsulfonyl)aminocarbonyl group, and a (stearylsulfonyl)aminocarbonyl group is preferred.

[0036] The phenyl group which may have a substituent includes a phenyl group in an embodiment having no substituent, and in an embodiment having a substituent, for example, an o-tolyl group, an m-tolyl group, a p-tolyl group, a 2,3-xylyl group, a 2,4-xylyl group, a 2,5-xylyl group, a 2,6-xylyl group, a 3,4-xylyl group, a 3,5-xylyl group, a 2,4,6-mesityl group, o-ethylphenyl group, m-ethylphenyl group, p-ethylphenyl group, o-propylphenyl group, m-propylphenyl group, p-propylphenyl group, o-i-propylphenyl group, m-i-propylphenyl group, p-i-propylphenyl group, o-butylphenyl group, m-butylphenyl group, p-butylphenyl group, o-i-butylphenyl group, m-i-butylphenyl group, p-i-butylphenyl group, o-t-butylphenyl group, m-t-butylphenyl group, p-t-butylphenyl group, o -pentylphenyl group, m-pentylphenyl group, p-pentylphenyl group, o-i-pentylphenyl group, m-i-pentylphenyl group, p-i-pentylphenyl group, o-hexylphenyl group, m-hexylphenyl group, p-hexylphenyl group, o-cyclohexylphenyl group, m-cyclohexylphenyl group, p-cyclohexylphenyl group, o-heptylphenyl group, m-heptylphenyl group, p-heptylphenyl group, o-octylphenyl group, m-octylphenyl group, p-octylphenyl group, o o-i-, o-methylphenyl, m-methylphenyl, p-methylphenyl ... Examples include a propoxyphenyl group, an m-i-propoxyphenyl group, a p-i-propoxyphenyl group, an o-vinyloxyphenyl group, an m-vinyloxyphenyl group, a p-vinyloxyphenyl group, an o-allyloxyphenyl group, an m-allyloxyphenyl group, a p-allyloxyphenyl group, an o-phenoxyphenyl group, an m-phenoxyphenyl group, a p-phenoxyphenyl group, an o-biphenyl group, an m-biphenyl group, a p-biphenyl group, an o-cumylphenyl group, an m-cumylphenyl group, and a p-cumylphenyl group.

[0037] Examples of the naphthyl group which may have a substituent include a 1-naphthyl group and a 2-naphthyl group in an embodiment having no substituent, and examples of the naphthyl group which may have a substituent include a 2-methyl-1-naphthyl group, a 3-methyl-1-naphthyl group, a 4-methyl-1-naphthyl group, a 5-methyl-1-naphthyl group, a 6-methyl-1-naphthyl group, a 7-methyl-1-naphthyl group, an 8-methyl-1-naphthyl group, a 2-ethyl-1-naphthyl group, a 3-ethyl-1-naphthyl group, a 4-ethyl-1-naphthyl group, a 5-ethyl-1-naphthyl group, a 6-ethyl-1-naphthyl group, a 7-ethyl-1-naphthyl group, naphthyl group, 8-ethyl-1-naphthyl group, 2-vinyl-1-naphthyl group, 3-vinyl-1-naphthyl group, 4-vinyl-1-naphthyl group, 5-vinyl-1-naphthyl group, 6-vinyl-1-naphthyl group, 7-vinyl-1-naphthyl group, 8-vinyl-1-naphthyl group, 2-allyl-1-naphthyl group, 3-allyl-1-naphthyl group, 4-allyl-1-naphthyl group, 5-allyl-1-naphthyl group, 6-allyl-1-naphthyl group, 7-allyl-1-naphthyl group, 8-allyl-1-naphthyl group, 2-methoxy-1-naphthyl group, 3-methoxy-1-naphthyl group, 4-methyl- oxy-1-naphthyl group, 5-methoxy-1-naphthyl group, 6-methoxy-1-naphthyl group, 7-methoxy-1-naphthyl group, 8-methoxy-1-naphthyl group, 2-ethoxy-1-naphthyl group, 3-ethoxy-1-naphthyl group, 4-ethoxy-1-naphthyl group, 5-ethoxy-1-naphthyl group, 6-ethoxy-1-naphthyl group, 7-ethoxy-1-naphthyl group, 8-ethoxy-1-naphthyl group, 2-vinyloxy-1-naphthyl group, 3-vinyloxy-1-naphthyl group, 4-vinyloxy-1-naphthyl group, 5-vinyloxy-1-naphthyl group, 6-vinyl oxy-1-naphthyl group, 7-vinyloxy-1-naphthyl group, 8-vinyloxy-1-naphthyl group, 2-allyloxy-1-naphthyl group, 3-allyloxy-1-naphthyl group, 4-allyloxy-1-naphthyl group, 5-allyloxy-1-naphthyl group, 6-allyloxy-1-naphthyl group, 7-allyloxy-1-naphthyl group, 8-allyloxy-1-naphthyl group, 1-methyl-2-naphthyl group, 3-methyl-2-naphthyl group, 4-methyl-2-naphthyl group, 5-methyl-2-naphthyl group, 6-methyl-2-naphthyl group, 7-methyl-2-naphthyl group,8-methyl-2-naphthyl group, 1-ethyl-2-naphthyl group, 3-ethyl-2-naphthyl group, 4-ethyl-2-naphthyl group, 5-ethyl-2-naphthyl group, 6-ethyl-2-naphthyl group, 7-ethyl-2-naphthyl group, 8-ethyl-2-naphthyl group, 1-vinyl-2-naphthyl group, 3-vinyl-2-naphthyl group, 4-vinyl-2-naphthyl group, 5-vinyl-2-naphthyl group, 6-vinyl-2-naphthyl group, 7-vinyl-2-naphthyl group aryl group, 8-vinyl-2-naphthyl group, 1-allyl-2-naphthyl group, 3-allyl-2-naphthyl group, 4-allyl-2-naphthyl group, 5-allyl-2-naphthyl group, 6-allyl-2-naphthyl group, 7-allyl-2-naphthyl group, 8-allyl-2-naphthyl group, 1-methoxy-2-naphthyl group, 3-methoxy-2-naphthyl group, 4-methoxy-2-naphthyl group, 5-methoxy-2-naphthyl group, 6-methoxy-2-naphthyl group , 7-methoxy-2-naphthyl group, 8-methoxy-2-naphthyl group, 1-ethoxy-2-naphthyl group, 3-ethoxy-2-naphthyl group, 4-ethoxy-2-naphthyl group, 5-ethoxy-2-naphthyl group, 6-ethoxy-2-naphthyl group, 7-ethoxy-2-naphthyl group, 8-ethoxy-2-naphthyl group, 1-vinyloxy-2-naphthyl group, 3-vinyloxy-2-naphthyl group, 4-vinyloxy-2-naphthyl group, 5-vinyloxy-2-naphthyl group, Examples of such an allyloxy group include an allyloxy-2-naphthyl group, a 6-vinyloxy-2-naphthyl group, a 7-vinyloxy-2-naphthyl group, an 8-vinyloxy-2-naphthyl group, a 1-allyloxy-2-naphthyl group, a 3-allyloxy-2-naphthyl group, a 4-allyloxy-2-naphthyl group, a 5-allyloxy-2-naphthyl group, a 6-allyloxy-2-naphthyl group, a 7-allyloxy-2-naphthyl group, and an 8-allyloxy-2-naphthyl group.

[0038] The phenylaminocarbonyl group which may have a substituent includes a phenylaminocarbonyl group in an embodiment having no substituent, and in an embodiment having a substituent, for example, an o-tolylaminocarbonyl group, an m-tolylaminocarbonyl group, a p-tolylaminocarbonyl group, a 2,3-xylylaminocarbonyl group, a 2,4-xylylaminocarbonyl group, a 2,5-xylylaminocarbonyl group, a 2,6-xylylaminocarbonyl group, a 3,4-xylylaminocarbonyl group, a 3,5-xylylaminocarbonyl group, a 2,4,6-mesitylaminocarbonyl group, a (o-ethylphenyl)aminocarbonyl group, a (m-ethylphenyl)aminocarbonyl group, a (p-ethylphenyl)aminocarbonyl group, a (o-propylphenyl)aminocarbonyl group, a (m-propylphenyl)aminocarbonyl group, a (p-propylphenyl)aminocarbonyl group, a (o-i-propylphenyl)aminocarbonyl group, a (m-i-propylphenyl)aminocarbonyl group, a (p-i-propylphenyl)aminocarbonyl group, a (o-butylphenyl)aminocarbonyl group, a (m-butylphenyl)aminocarbonyl group, a (p-butylphenyl)aminocarbonyl group, (o-i-butylphenyl)aminocarbonyl group, (m-i-butylphenyl)aminocarbonyl group, (p-i-butylphenyl)aminocarbonyl group, (o-t-butylphenyl)aminocarbonyl group, (m-t-butylphenyl)aminocarbonyl group, (p-t-butylphenyl)aminocarbonyl group, (o-pentylphenyl)aminocarbonyl group, (m-pentylphenyl)aminocarbonyl group, (p-pentylphenyl)aminocarbonyl group, (o-i-pentylphenyl)aminocarbonyl group, (m-i- a (pentylphenyl)aminocarbonyl group, a (p-i-pentylphenyl)aminocarbonyl group, an (o-hexylphenyl)aminocarbonyl group, a (m-hexylphenyl)aminocarbonyl group, a (p-hexylphenyl)aminocarbonyl group, an (o-cyclohexylphenyl)aminocarbonyl group, a (m-cyclohexylphenyl)aminocarbonyl group, a (p-cyclohexylphenyl)aminocarbonyl group, an (o-heptylphenyl)aminocarbonyl group, a (m-heptylphenyl)aminocarbonyl group, a (p-heptylphenyl)aminocarbonyl group,(o-octylphenyl)aminocarbonyl group, (m-octylphenyl)aminocarbonyl group, (p-octylphenyl)aminocarbonyl group, (o-2-ethylhexylphenyl)aminocarbonyl group, (m-2-ethylhexylphenyl)aminocarbonyl group, (p-2-ethylhexylphenyl)aminocarbonyl group, (o-vinylphenyl)aminocarbonyl group, (m-vinylphenyl)aminocarbonyl group, (p-vinylphenyl)aminocarbonyl group, (o-allylphenyl ) aminocarbonyl group, (m-allylphenyl) aminocarbonyl group, (p-allylphenyl) aminocarbonyl group, (o-methoxyphenyl) aminocarbonyl group, (m-methoxyphenyl) aminocarbonyl group, (p-methoxyphenyl) aminocarbonyl group, (o-ethoxyphenyl) aminocarbonyl group, (m-ethoxyphenyl) aminocarbonyl group, (p-ethoxyphenyl) aminocarbonyl group, (o-propoxyphenyl) aminocarbonyl group, (m-propoxyphenyl) Aminocarbonyl group, (p-propoxyphenyl)aminocarbonyl group, (o-i-propoxyphenyl)aminocarbonyl group, (m-i-propoxyphenyl)aminocarbonyl group, (p-i-propoxyphenyl)aminocarbonyl group, (o-vinyloxyphenyl)aminocarbonyl group, (m-vinyloxyphenyl)aminocarbonyl group, (p-vinyloxyphenyl)aminocarbonyl group, (o-allyloxyphenyl)aminocarbonyl group, (m-allyloxyphenyl)amino carbonyl group, (p-allyloxyphenyl)aminocarbonyl group, (o-phenoxyphenyl)aminocarbonyl group, (m-phenoxyphenyl)aminocarbonyl group, (p-phenoxyphenyl)aminocarbonyl group, o-biphenylaminocarbonyl group, m-biphenylaminocarbonyl group, p-biphenylaminocarbonyl group, (o-cumylphenyl)aminocarbonyl group, (m-cumylphenyl)aminocarbonyl group, (p-cumylphenyl)aminocarbonyl group, etc. Among these, unsubstituted phenylaminocarbonyl group, o-tolylaminocarbonyl group, andm-tolylaminocarbonyl group, p-tolylaminocarbonyl group, 2,3-xylylaminocarbonyl group, 2,4-xylylaminocarbonyl group, 2,5-xylylaminocarbonyl group, 2,6-xylylaminocarbonyl group, 3,4-xylylaminocarbonyl group, 3,5-xylylaminocarbonyl group, 2,4,6-mesitylaminocarbonyl group, (o-ethylphenyl)aminocarbonyl group, (m-ethylphenyl)aminocarbonyl group, (p-ethylphenyl)aminocarbonyl group, (o-methoxyphenyl) Aminocarbonyl group, (m-methoxyphenyl)aminocarbonyl group, (p-methoxyphenyl)aminocarbonyl group, (o-ethoxyphenyl)aminocarbonyl group, (m-ethoxyphenyl)aminocarbonyl group, (p-ethoxyphenyl)aminocarbonyl group, (o-vinyloxyphenyl)aminocarbonyl group, (m-vinyloxyphenyl)aminocarbonyl group, (p-vinyloxyphenyl)aminocarbonyl group, (o-allyloxyphenyl)aminocarbonyl group, (m-allyloxyphenyl)aminocarbonyl group and (p-allyloxyphenyl)aminocarbonyl group, and preferably any of an unsubstituted phenylaminocarbonyl group, an o-tolylaminocarbonyl group, an m-tolylaminocarbonyl group, a p-tolylaminocarbonyl group, an (o-ethylphenyl)aminocarbonyl group, an (m-ethylphenyl)aminocarbonyl group, a (p-ethylphenyl)aminocarbonyl group, an (o-methoxyphenyl)aminocarbonyl group, an (m-methoxyphenyl)aminocarbonyl group, and a (p-methoxyphenyl)aminocarbonyl group. It is more preferably any one of a carbonyl group, an (o-ethoxyphenyl)aminocarbonyl group, an (m-ethoxyphenyl)aminocarbonyl group, a (p-ethoxyphenyl)aminocarbonyl group, an (o-vinyloxyphenyl)aminocarbonyl group, an (m-vinyloxyphenyl)aminocarbonyl group, a (p-vinyloxyphenyl)aminocarbonyl group, an (o-allyloxyphenyl)aminocarbonyl group, an (m-allyloxyphenyl)aminocarbonyl group, and a (p-allyloxyphenyl)aminocarbonyl group.

[0039] The phenylsulfonylaminocarbonyl group which may have a substituent includes, in an embodiment having no substituent, a phenylsulfonylaminocarbonyl group, and in an embodiment having a substituent, for example, an (o-tolylsulfonyl)aminocarbonyl group, an (m-tolylsulfonyl)aminocarbonyl group, a (p-tolylsulfonyl)aminocarbonyl group, a (2,3-xylylsulfonyl)aminocarbonyl group, a (2,4-xylylsulfonyl)aminocarbonyl group, a (2,5-xylylsulfonyl)aminocarbonyl group, a (2,6-xylylsulfonyl)aminocarbonyl group, (3,4-xylylsulfonyl)aminocarbonyl group, (3,5-xylylsulfonyl)aminocarbonyl group, (2,4,6-mesitylsulfonyl)aminocarbonyl group, ((o-ethylphenyl)sulfonyl)aminocarbonyl group, ((m-ethylphenyl)sulfonyl)aminocarbonyl group, ((p-ethylphenyl)sulfonyl)aminocarbonyl group, ((o-propylphenyl)sulfonyl)aminocarbonyl group, ((m-propylphenyl)sulfonyl)aminocarbonyl group, ((p-propylphenyl)sulfonyl (o-i-propylphenyl)sulfonyl)aminocarbonyl group, ((m-i-propylphenyl)sulfonyl)aminocarbonyl group, ((p-i-propylphenyl)sulfonyl)aminocarbonyl group, ((o-butylphenyl)sulfonyl)aminocarbonyl group, ((m-butylphenyl)sulfonyl)aminocarbonyl group, ((p-butylphenyl)sulfonyl)aminocarbonyl group, ((o-i-butylphenyl)sulfonyl)aminocarbonyl group, ((m-i-butylphenyl)sulfonyl)aminocarbonyl group carbonyl group, a ((p-i-butylphenyl)sulfonyl)aminocarbonyl group, a ((o-t-butylphenyl)sulfonyl)aminocarbonyl group, a ((m-t-butylphenyl)sulfonyl)aminocarbonyl group, a ((p-t-butylphenyl)sulfonyl)aminocarbonyl group, a ((o-pentylphenyl)sulfonyl)aminocarbonyl group, a ((m-pentylphenyl)sulfonyl)aminocarbonyl group, a ((p-pentylphenyl)sulfonyl)aminocarbonyl group, a ((o-i-pentylphenyl)sulfonyl)aminocarbonyl group,((m-i-pentylphenyl)sulfonyl)aminocarbonyl group, ((p-i-pentylphenyl)sulfonyl)aminocarbonyl group, ((o-hexylphenyl)sulfonyl)aminocarbonyl group, ((m-hexylphenyl)sulfonyl)aminocarbonyl group, ((p-hexylphenyl)sulfonyl)aminocarbonyl group, ((o-cyclohexylphenyl)sulfonyl)aminocarbonyl group, ((m-cyclohexylphenyl)sulfonyl)aminocarbonyl group, ((p-cyclohexylphenyl)sulfonyl)aminocarbonyl group, ( (o-heptylphenyl)sulfonyl)aminocarbonyl group, ((m-heptylphenyl)sulfonyl)aminocarbonyl group, ((p-heptylphenyl)sulfonyl)aminocarbonyl group, ((o-octylphenyl)sulfonyl)aminocarbonyl group, ((m-octylphenyl)sulfonyl)aminocarbonyl group, ((p-octylphenyl)sulfonyl)aminocarbonyl group, ((o-2-ethylhexylphenyl)sulfonyl)aminocarbonyl group, ((m-2-ethylhexylphenyl)sulfonyl)aminocarbonyl group, ((p-2 (o-ethylhexylphenyl)sulfonyl)aminocarbonyl group, (o-vinylphenyl)sulfonyl)aminocarbonyl group, ((m-vinylphenyl)sulfonyl)aminocarbonyl group, ((p-vinylphenyl)sulfonyl)aminocarbonyl group, ((o-allylphenyl)sulfonyl)aminocarbonyl group, ((m-allylphenyl)sulfonyl)aminocarbonyl group, ((p-allylphenyl)sulfonyl)aminocarbonyl group, ((o-methoxyphenyl)sulfonyl)aminocarbonyl group, ((m-methoxyphenyl)sulfonyl)aminocarbonyl group aminocarbonyl group, ((p-methoxyphenyl)sulfonyl)aminocarbonyl group, ((o-ethoxyphenyl)sulfonyl)aminocarbonyl group, ((m-ethoxyphenyl)sulfonyl)aminocarbonyl group, ((p-ethoxyphenyl)sulfonyl)aminocarbonyl group, ((o-propoxyphenyl)sulfonyl)aminocarbonyl group, ((m-propoxyphenyl)sulfonyl)aminocarbonyl group, ((p-propoxyphenyl)sulfonyl)aminocarbonyl group, ((o-i-propoxyphenyl)sulfonyl)aminocarbonyl group,((m-i-propoxyphenyl)sulfonyl)aminocarbonyl group, ((p-i-propoxyphenyl)sulfonyl)aminocarbonyl group, ((o-vinyloxyphenyl)sulfonyl)aminocarbonyl group, ((m-vinyloxyphenyl)sulfonyl)aminocarbonyl group, ((p-vinyloxyphenyl)sulfonyl)aminocarbonyl group, ((o-allyloxyphenyl)sulfonyl)aminocarbonyl group, ((m-allyloxyphenyl)sulfonyl)aminocarbonyl group, ((p-allyloxyphenyl)sulfonyl)aminocarbonyl group, Examples thereof include an (o-phenoxyphenyl)sulfonyl)aminocarbonyl group, an ((m-phenoxyphenyl)sulfonyl)aminocarbonyl group, a ((p-phenoxyphenyl)sulfonyl)aminocarbonyl group, an (o-biphenylsulfonyl)aminocarbonyl group, a (m-biphenylsulfonyl)aminocarbonyl group, a (p-biphenylsulfonyl)aminocarbonyl group, an ((o-cumylphenyl)sulfonyl)aminocarbonyl group, a ((m-cumylphenyl)sulfonyl)aminocarbonyl group, and a ((p-cumylphenyl)sulfonyl)aminocarbonyl group. Among these, from the viewpoint of improving compatibility with leuco dyes to increase color development sensitivity, and from the viewpoint of suppressing thermal motion of molecules to easily improve storage stability of the background, unsubstituted phenylsulfonylaminocarbonyl groups, (o-tolylsulfonyl)aminocarbonyl groups, (m-tolylsulfonyl)aminocarbonyl groups, (p-tolylsulfonyl)aminocarbonyl groups, (2,3-xylylsulfonyl)aminocarbonyl groups, (2,4-xylylsulfonyl)aminocarbonyl groups, (2,5-xylylsulfonyl)aminocarbonyl groups, (2,6 a (3,4-xylylsulfonyl)aminocarbonyl group, a (3,5-xylylsulfonyl)aminocarbonyl group, a (2,4,6-mesitylsulfonyl)aminocarbonyl group, a ((o-ethylphenyl)sulfonyl)aminocarbonyl group, a ((m-ethylphenyl)sulfonyl)aminocarbonyl group, a ((p-ethylphenyl)sulfonyl)aminocarbonyl group, a ((o-methoxyphenyl)sulfonyl)aminocarbonyl group, a ((m-methoxyphenyl)sulfonyl)aminocarbonyl group,((p-methoxyphenyl)sulfonyl)aminocarbonyl group, ((o-ethoxyphenyl)sulfonyl)aminocarbonyl group, ((m-ethoxyphenyl)sulfonyl)aminocarbonyl group, ((p-ethoxyphenyl)sulfonyl)aminocarbonyl group, ((o-vinyloxyphenyl)sulfonyl)aminocarbonyl group, ((m-vinyloxyphenyl)sulfonyl)aminocarbonyl group, ((p-vinyloxyphenyl)sulfonyl)aminocarbonyl group, ((o-allylo The alkyl group is preferably any one of an unsubstituted phenylsulfonylaminocarbonyl group, an (o-tolylsulfonyl)aminocarbonyl group, an (m-tolylsulfonyl)aminocarbonyl group, an (p-tolylsulfonyl)aminocarbonyl group, an (o-ethylphenyl)sulfonyl)aminocarbonyl group, an (m-allyloxyphenyl)sulfonyl)aminocarbonyl group, an (p-allyloxyphenyl)sulfonyl)aminocarbonyl group, and more preferably any one of an unsubstituted phenylsulfonylaminocarbonyl group, an (o-tolylsulfonyl)aminocarbonyl group, an (m-tolylsulfonyl)aminocarbonyl group, an (p-tolylsulfonyl)aminocarbonyl group, an (o-ethylphenyl)sulfonyl)aminocarbonyl group, an (m-allyloxyphenyl)sulfonyl)aminocarbonyl group, an (p-allyloxyphenyl)s ... a ((m-ethylphenyl)sulfonyl)aminocarbonyl group, a ((p-ethylphenyl)sulfonyl)aminocarbonyl group, a ((o-methoxyphenyl)sulfonyl)aminocarbonyl group, a ((m-methoxyphenyl)sulfonyl)aminocarbonyl group, a ((p-methoxyphenyl)sulfonyl)aminocarbonyl group, a ((o-ethoxyphenyl)sulfonyl)aminocarbonyl group, a ((m-ethoxyphenyl)sulfonyl)aminocarbonyl group, a ((p-ethoxyphenyl)sulfonyl More preferably, the alkyl group is any one of a ((o-vinyloxyphenyl)sulfonyl)aminocarbonyl group, a ((m-vinyloxyphenyl)sulfonyl)aminocarbonyl group, a ((p-vinyloxyphenyl)sulfonyl)aminocarbonyl group, a ((o-allyloxyphenyl)sulfonyl)aminocarbonyl group, a ((m-allyloxyphenyl)sulfonyl)aminocarbonyl group, and a ((p-allyloxyphenyl)sulfonyl)aminocarbonyl group.

[0040] The benzoyl group which may have a substituent includes a benzoyl group in an embodiment having no substituent, and examples of the benzoyl group which may have a substituent include an o-methylbenzoyl group, an m-methylbenzoyl group, a p-methylbenzoyl group, a 2,3-dimethylbenzoyl group, a 2,4-dimethylbenzoyl group, a 2,5-dimethylbenzoyl group, a 2,6-dimethylbenzoyl group, a 3,4-dimethylbenzoyl group, a 3,5-dimethylbenzoyl group, a 2,4,6-trimethylbenzoyl group, an o-ethylbenzoyl group, an m-ethylbenzoyl group, a p-ethylbenzoyl group, an o-methylbenzoyl group, an m-ethylbenzoyl group, a p-ethylbenzoyl group, an o-methylbenzoyl group, an m-methylbenzoyl group, a p-methyl ... m-methylbenzoyl group, an m-methylbenzoyl group, a p-methylbenzoyl group, an o-methylbenzoyl group, an m-methylbenzoyl group, a p-methylbenzoyl group, an m-methylbenzoyl group, an m-methylbenzoyl group, an m-methyl propylbenzoyl group, m-propylbenzoyl group, p-propylbenzoyl group, o-i-propylbenzoyl group, m-i-propylbenzoyl group, p-i-propylbenzoyl group, o-butylbenzoyl group, m-butylbenzoyl group, p-butylbenzoyl group, o-i-butylbenzoyl group, m-i-butylbenzoyl group, p-i-butylbenzoyl group, o-t-butylbenzoyl group, m-t-butylbenzoyl group, p-t-butylbenzoyl group, o-pentylbenzoyl group, m-pentylbenzoyl group, p-pentylbenzoyl group, o-i-pentyl Benzoyl group, m-i-pentylbenzoyl group, p-i-pentylbenzoyl group, o-hexylbenzoyl group, m-hexylbenzoyl group, p-hexylbenzoyl group, o-cyclohexylbenzoyl group, m-cyclohexylbenzoyl group, p-cyclohexylbenzoyl group, o-heptylbenzoyl group, m-heptylbenzoyl group, p-heptylbenzoyl group, o-octylbenzoyl group, m-octylbenzoyl group, p-octylbenzoyl group, o-2-ethylhexylbenzoyl group, m-2-ethylhexylbenzoyl group, p-2-ethylhexyl an o-vinylbenzoyl group, an m-vinylbenzoyl group, a p-vinylbenzoyl group, an o-allylbenzoyl group, an m-allylbenzoyl group, a p-allylbenzoyl group, an o-methoxybenzoyl group, an m-methoxybenzoyl group, a p-methoxybenzoyl group, an o-ethoxybenzoyl group, an m-ethoxybenzoyl group, a p-ethoxybenzoyl group, an o-propoxybenzoyl group, an m-propoxybenzoyl group, a p-propoxybenzoyl group, an o-i-propoxybenzoyl group, an m-i-propoxybenzoyl group, or a p-i-propoxybenzoyl group,Examples thereof include an o-vinyloxybenzoyl group, an m-vinyloxybenzoyl group, a p-vinyloxybenzoyl group, an o-allyloxybenzoyl group, an m-allyloxybenzoyl group, a p-allyloxybenzoyl group, an o-phenoxybenzoyl group, an m-phenoxybenzoyl group, a p-phenoxybenzoyl group, an o-cumylbenzoyl group, an m-cumylbenzoyl group, and a p-cumylbenzoyl group. Among these, from the viewpoint of improving compatibility with leuco dyes to increase color development sensitivity, and from the viewpoint of suppressing thermal motion of molecules to easily improve storage stability of the background, unsubstituted benzoyl groups, o-methylbenzoyl groups, m-methylbenzoyl groups, p-methylbenzoyl groups, 2,3-dimethylbenzoyl groups, 2,4-dimethylbenzoyl groups, 2,5-dimethylbenzoyl groups, 2,6-dimethylbenzoyl groups, 3,4-dimethylbenzoyl groups, 3,5-dimethylbenzoyl groups, 2,4,6-trimethylbenzoyl groups, o-ethylbenzoyl groups, m-ethylbenzoyl groups, p-ethylbenzoyl groups, o-methoxybenzoyl groups, m-methoxybenzoyl groups, p-methoxybenzoyl groups, o-ethoxybenzoyl groups, m-ethoxybenzoyl groups, p-ethoxybenzoyl groups, o-vinyloxybenzoyl groups, m-vinyloxybenzoyl groups, Preferably, the alkyl group is any one of an o-methyloxybenzoyl group, a p-vinyloxybenzoyl group, an o-allyloxybenzoyl group, an m-allyloxybenzoyl group, and a p-allyloxybenzoyl group, and more preferably any one of an unsubstituted benzoyl group, an o-methylbenzoyl group, a m-methylbenzoyl group, a p-methylbenzoyl group, an o-ethylbenzoyl group, a m-ethylbenzoyl group, a p-ethylbenzoyl group, an o-methoxybenzoyl group, a m-methoxybenzoyl group, a p-methoxybenzoyl group, an o-ethoxybenzoyl group, a m-ethoxybenzoyl group, a p-ethoxybenzoyl group, an o-vinyloxybenzoyl group, a m-vinyloxybenzoyl group, a p-vinyloxybenzoyl group, an o-allyloxybenzoyl group, a m-allyloxybenzoyl group, and a p-allyloxybenzoyl group.

[0041] Examples of the naphthoyl group which may have a substituent include a 1-naphthoyl group and a 2-naphthoyl group in an embodiment having no substituent, and examples of the naphthoyl group which may have a substituent include a 2-methyl-1-naphthoyl group, a 3-methyl-1-naphthoyl group, a 4-methyl-1-naphthoyl group, a 5-methyl-1-naphthoyl group, a 6-methyl-1-naphthoyl group, a 7-methyl-1-naphthoyl group, an 8-methyl-1-naphthoyl group, a 2-ethyl-1-naphthoyl group, a 3-ethyl-1-naphthoyl group, a 4-ethyl-1-naphthoyl group, a 5-ethyl-1-naphthoyl group, a 6-ethyl- 1-naphthoyl group, 7-ethyl-1-naphthoyl group, 8-ethyl-1-naphthoyl group, 2-vinyl-1-naphthoyl group, 3-vinyl-1-naphthoyl group, 4-vinyl-1-naphthoyl group, 5-vinyl-1-naphthoyl group, 6-vinyl-1-naphthoyl group, 7-vinyl-1-naphthoyl group, 8-vinyl-1-naphthoyl group, 2-allyl-1-naphthoyl group, 3-allyl-1-naphthoyl group, 4-allyl-1-naphthoyl group, 5-allyl-1-naphthoyl group, 6-allyl-1-naphthoyl group, 7-allyl-1-naphthoyl group, 8-allyl-1-naphthoyl group, 2-methoxy-1-naphthoyl group, 3-methoxy-1-naphthoyl group, 4-methoxy-1-naphthoyl group, 5-methoxy-1-naphthoyl group, 6-methoxy-1-naphthoyl group, 7-methoxy-1-naphthoyl group, 8-methoxy-1-naphthoyl group, 2-ethoxy-1-naphthoyl group, 3-ethoxy-1-naphthoyl group, 4-ethoxy-1-naphthoyl group, 5-ethoxy-1-naphthoyl group, 6-ethoxy-1-naphthoyl group, 7-ethoxy-1-naphthoyl group, 8-ethoxy-1-naphthoyl group, 2-vinyloxy-1-naphthoyl group, 3-vinyloxy-1-naphthoyl group, allyloxy-1-naphthoyl group, 4-vinyloxy-1-naphthoyl group, 5-vinyloxy-1-naphthoyl group, 6-vinyloxy-1-naphthoyl group, 7-vinyloxy-1-naphthoyl group, 8-vinyloxy-1-naphthoyl group, 2-allyloxy-1-naphthoyl group, 3-allyloxy-1-naphthoyl group, 4-allyloxy-1-naphthoyl group, 5-allyloxy-1-naphthoyl group, 6-allyloxy-1-naphthoyl group, 7-allyloxy-1-naphthoyl group, 8-allyloxy-1-naphthoyl group, 1-methyl-2-naphthoyl group,3-methyl-2-naphthoyl group, 4-methyl-2-naphthoyl group, 5-methyl-2-naphthoyl group, 6-methyl-2-naphthoyl group, 7-methyl-2-naphthoyl group, 8-methyl-2-naphthoyl group, 1-ethyl-2-naphthoyl group, 3-ethyl-2-naphthoyl group, 4-ethyl-2-naphthoyl group, 5-ethyl-2-naphthoyl group, 6-ethyl-2-naphthoyl group, 7-ethyl-2-naphthoyl group, 8-ethyl-2-naphthoyl group, 1-vinyl-2-naphthoyl group, 3-vinyl-2-naphthoyl a vinyl group, a 4-vinyl-2-naphthoyl group, a 5-vinyl-2-naphthoyl group, a 6-vinyl-2-naphthoyl group, a 7-vinyl-2-naphthoyl group, a 8-vinyl-2-naphthoyl group, a 1-allyl-2-naphthoyl group, a 3-allyl-2-naphthoyl group, a 4-allyl-2-naphthoyl group, a 5-allyl-2-naphthoyl group, a 6-allyl-2-naphthoyl group, a 7-allyl-2-naphthoyl group, a 8-allyl-2-naphthoyl group, a 1-methoxy-2-naphthoyl group, a 3-methoxy-2-naphthoyl group, a 4-methoxy- 2-naphthoyl group, 5-methoxy-2-naphthoyl group, 6-methoxy-2-naphthoyl group, 7-methoxy-2-naphthoyl group, 8-methoxy-2-naphthoyl group, 1-ethoxy-2-naphthoyl group, 3-ethoxy-2-naphthoyl group, 4-ethoxy-2-naphthoyl group, 5-ethoxy-2-naphthoyl group, 6-ethoxy-2-naphthoyl group, 7-ethoxy-2-naphthoyl group, 8-ethoxy-2-naphthoyl group, 1-vinyloxy-2-naphthoyl group, 3-vinyloxy-2-naphthoyl group, 4 1-allyloxy-2-naphthoyl group, 5-vinyloxy-2-naphthoyl group, 6-vinyloxy-2-naphthoyl group, 7-vinyloxy-2-naphthoyl group, 8-vinyloxy-2-naphthoyl group, 1-allyloxy-2-naphthoyl group, 3-allyloxy-2-naphthoyl group, 4-allyloxy-2-naphthoyl group, 5-allyloxy-2-naphthoyl group, 6-allyloxy-2-naphthoyl group, 7-allyloxy-2-naphthoyl group, 8-allyloxy-2-naphthoyl group, etc. Among these, from the viewpoint of improving compatibility with leuco dyes to enhance color development sensitivity, and suppressing thermal motion of molecules to easily improve storage stability of background areas, preferred are naphthoyl groups having no substituent, 2-methyl-1-naphthoyl group, 3-methyl-1-naphthoyl group,4-methyl-1-naphthoyl group, 5-methyl-1-naphthoyl group, 6-methyl-1-naphthoyl group, 7-methyl-1-naphthoyl group, 8-methyl-1-naphthoyl group, 2-methoxy-1-naphthoyl group, 3-methoxy-1-naphthoyl group, 4-methoxy-1-naphthoyl group, 5-methoxy-1-naphthoyl group, 6-methoxy-1-naphthoyl group, 7-methoxy-1-naphthoyl group, 8-methoxy-1-naphthoyl group, 2-vinyl-1-naphthoyl group, 3-vinyl-1-naphthoyl group, 4-vinyl-1-naphthoyl group, 5-vinyl-1-naphthoyl group, 6-vinyl vinyloxy-1-naphthoyl group, 7-vinyl-1-naphthoyl group, 8-vinyl-1-naphthoyl group, 2-vinyloxy-1-naphthoyl group, 3-vinyloxy-1-naphthoyl group, 4-vinyloxy-1-naphthoyl group, 5-vinyloxy-1-naphthoyl group, 6-vinyloxy-1-naphthoyl group, 7-vinyloxy-1-naphthoyl group, 8-vinyloxy-1-naphthoyl group, 1-methyl-2-naphthoyl group, 3-methyl-2-naphthoyl group, 4-methyl-2-naphthoyl group, 5-methyl-2-naphthoyl group, 6-methyl-2-naphthoyl group, 7-methyl-2 -naphthoyl group, 8-methyl-2-naphthoyl group, 1-methoxy-2-naphthoyl group, 3-methoxy-2-naphthoyl group, 4-methoxy-2-naphthoyl group, 5-methoxy-2-naphthoyl group, 6-methoxy-2-naphthoyl group, 7-methoxy-2-naphthoyl group, 8-methoxy-2-naphthoyl group, 1-vinyl-2-naphthoyl group, 3-vinyl-2-naphthoyl group, 4-vinyl-2-naphthoyl group, 5-vinyl-2-naphthoyl group, 6-vinyl-2-naphthoyl group, 7-vinyl-2-naphthoyl group, 8-vinyl-2-naphthoyl group, 1-vinyloxy-2 -naphthoyl group, 3-vinyloxy-2-naphthoyl group, 4-vinyloxy-2-naphthoyl group, 5-vinyloxy-2-naphthoyl group, 6-vinyloxy-2-naphthoyl group, 7-vinyloxy-2-naphthoyl group, or 8-vinyloxy-2-naphthoyl group; and preferred are unsubstituted naphthoyl group, 2-methyl-1-naphthoyl group, 3-methyl-1-naphthoyl group, 4-methyl-1-naphthoyl group, 5-methyl-1-naphthoyl group, 6-methyl-1-naphthoyl group, 7-methyl-1-naphthoyl group, or 8-methyl-1-naphthoyl group.2-methoxy-1-naphthoyl group, 3-methoxy-1-naphthoyl group, 4-methoxy-1-naphthoyl group, 5-methoxy-1-naphthoyl group, 6-methoxy-1-naphthoyl group, 7-methoxy-1-naphthoyl group, 8-methoxy-1-naphthoyl group, 1-methyl-2-naphthoyl group, 3-methyl-2-naphthoyl group, 4-methyl-2-naphthoyl group, 5-methyl-2-naphthoyl group, 6 It is more preferable that the alkyl group is any one of a 1-methyl-2-naphthoyl group, a 7-methyl-2-naphthoyl group, an 8-methyl-2-naphthoyl group, a 1-methoxy-2-naphthoyl group, a 3-methoxy-2-naphthoyl group, a 4-methoxy-2-naphthoyl group, a 5-methoxy-2-naphthoyl group, a 6-methoxy-2-naphthoyl group, a 7-methoxy-2-naphthoyl group, and an 8-methoxy-2-naphthoyl group.

[0042] The arylalkyl group having 7 to 48 carbon atoms, which may have a substituent, is a group in which one hydrogen atom of an alkyl group is removed and an aryl group is bonded to the alkyl group.

[0043] Examples of unsubstituted arylalkyl groups having 7 to 48 carbon atoms include benzyl, 1-phenylethyl, 2-phenylethyl, 1-phenylpropyl, 2-phenylpropyl, 3-phenylpropyl, 1-phenylbutyl, 2-phenylbutyl, 3-phenylbutyl, 4-phenylbutyl, cumyl, naphthylmethyl, 1-naphthylethyl, 2-naphthylethyl, 1-naphthylpropyl, 2-naphthylpropyl, 3-naphthylpropyl, 1-naphthylbutyl, 2-naphthylbutyl, 3-naphthylbutyl, and 4-naphthylbutyl groups.

[0044] Examples of the substituted arylalkyl group having 7 to 48 carbon atoms include an o-methylbenzyl group, an m-methylbenzyl group, a p-methylbenzyl group, an o-vinylbenzyl group, an m-vinylbenzyl group, a p-vinylbenzyl group, an o-methoxybenzyl group, an m-methoxybenzyl group, a p-methoxybenzyl group, an o-vinyloxybenzyl group, an m-vinyloxybenzyl group, a p-vinyloxybenzyl group, an o-allyloxybenzyl group, an m-allyloxybenzyl group, a p-allyloxybenzyl group, an o-methylcumyl group, an m-methylcumyl group, a p-methylcumyl group, an o-methoxycumyl group, an m-methoxycumyl group, and a p-methoxycumyl group.

[0045] Examples of the arylalkylcarbonyl group having 8 to 49 carbon atoms, which may have a substituent, include the following: Among these, an arylalkylcarbonyl group having 8 to 24 carbon atoms is preferred from the viewpoint of improving compatibility with the leuco dye to increase color development sensitivity, and from the viewpoint of suppressing thermal motion of molecules to easily improve storage stability of the background portion.

[0046] Examples of the unsubstituted arylalkylcarbonyl group having 8 to 49 carbon atoms include benzylcarbonyl, 1-phenylethylcarbonyl, 2-phenylethylcarbonyl, 1-phenylpropylcarbonyl, 2-phenylpropylcarbonyl, 3-phenylpropylcarbonyl, 1-phenylbutylcarbonyl, 2-phenylbutylcarbonyl, 3-phenylbutylcarbonyl, 4-phenylbutylcarbonyl, cumylcarbonyl, naphthylmethylcarbonyl, 1-naphthylethylcarbonyl, 2-naphthylethylcarbonyl, 1-naphthylpropylcarbonyl, 2-naphthylpropylcarbonyl, 3-naphthylpropylcarbonyl, 1-naphthylbutylcarbonyl, 2-naphthylbutylcarbonyl, 3-naphthylbutylcarbonyl, and 4-naphthylbutylcarbonyl. Among these, any one of a benzylcarbonyl group, a 1-phenylethylcarbonyl group, a 2-phenylethylcarbonyl group, a 1-phenylpropylcarbonyl group, a 2-phenylpropylcarbonyl group, a 3-phenylpropylcarbonyl group, a cumylcarbonyl group, a naphthylmethylcarbonyl group, a 1-naphthylethylcarbonyl group, a 2-naphthylethylcarbonyl group, a 1-naphthylpropylcarbonyl group, a 2-naphthylpropylcarbonyl group, and a 3-naphthylpropylcarbonyl group is preferred.

[0047] Examples of the substituted arylalkylcarbonyl group having 8 to 49 carbon atoms include an o-methylbenzylcarbonyl group, an m-methylbenzylcarbonyl group, a p-methylbenzylcarbonyl group, an o-vinylbenzylcarbonyl group, an m-vinylbenzylcarbonyl group, a p-vinylbenzylcarbonyl group, an o-methoxybenzylcarbonyl group, an m-methoxybenzylcarbonyl group, a p-methoxybenzylcarbonyl group, an o-vinyloxybenzylcarbonyl group, an m-vinyloxybenzylcarbonyl group, a p-vinyloxybenzylcarbonyl group, an o-allyloxybenzylcarbonyl group, an m-allyloxybenzylcarbonyl group, a p-allyloxybenzylcarbonyl group, an o-methylcumylcarbonyl group, an m-methylcumylcarbonyl group, a p-methylcumylcarbonyl group, an o-methoxycumylcarbonyl group, an m-methoxycumylcarbonyl group, and a p-methoxycumylcarbonyl group. Among these, any one of an o-methylbenzylcarbonyl group, an m-methylbenzylcarbonyl group, a p-methylbenzylcarbonyl group, an o-vinylbenzylcarbonyl group, an m-vinylbenzylcarbonyl group, a p-vinylbenzylcarbonyl group, an o-methoxybenzylcarbonyl group, an m-methoxybenzylcarbonyl group, a p-methoxybenzylcarbonyl group, an o-vinyloxybenzylcarbonyl group, an m-vinyloxybenzylcarbonyl group, a p-vinyloxybenzylcarbonyl group, an o-allyloxybenzylcarbonyl group, an m-allyloxybenzylcarbonyl group, and a p-allyloxybenzylcarbonyl group is preferred.

[0048] Examples of the arylalkylaminocarbonyl group having 8 to 49 carbon atoms, which may have a substituent, include the following: Among these, an arylalkylaminocarbonyl group having 8 to 24 carbon atoms is preferred from the viewpoint of improving compatibility with the leuco dye to increase color development sensitivity, and from the viewpoint of suppressing thermal motion of molecules to easily improve storage stability of the background portion.

[0049] Examples of unsubstituted arylalkylaminocarbonyl groups having 8 to 49 carbon atoms include benzylaminocarbonyl groups, (1-phenylethyl)aminocarbonyl groups, (2-phenylethyl)aminocarbonyl groups, (1-phenylpropyl)aminocarbonyl groups, (2-phenylpropyl)aminocarbonyl groups, (3-phenylpropyl)aminocarbonyl groups, (1-phenylbutyl)aminocarbonyl groups, (2-phenylbutyl)aminocarbonyl groups, (3-phenylbutyl)aminocarbonyl groups, and (4-phenylbutyl)aminocarbonyl groups. Examples thereof include an aminocarbonyl group, a cumylaminocarbonyl group, a (naphthylmethyl)aminocarbonyl group, a (1-naphthylethyl)aminocarbonyl group, a (2-naphthylethyl)aminocarbonyl group, a (1-naphthylpropyl)aminocarbonyl group, a (2-naphthylpropyl)aminocarbonyl group, a (3-naphthylpropyl)aminocarbonyl group, a (1-naphthylbutyl)aminocarbonyl group, a (2-naphthylbutyl)aminocarbonyl group, a (3-naphthylbutyl)aminocarbonyl group, and a (4-naphthylbutyl)aminocarbonyl group. Among these, any one of a benzylaminocarbonyl group, a (1-phenylethyl)aminocarbonyl group, a (2-phenylethyl)aminocarbonyl group, a (1-phenylpropyl)aminocarbonyl group, a (2-phenylpropyl)aminocarbonyl group, a (3-phenylpropyl)aminocarbonyl group, a cumylaminocarbonyl group, a (naphthylmethyl)aminocarbonyl group, a (1-naphthylethyl)aminocarbonyl group, a (2-naphthylethyl)aminocarbonyl group, a (1-naphthylpropyl)aminocarbonyl group, a (2-naphthylpropyl)aminocarbonyl group, and a (3-naphthylpropyl)aminocarbonyl group is preferred.

[0050] Examples of substituted arylalkylaminocarbonyl groups having 8 to 49 carbon atoms include (o-methylbenzyl)aminocarbonyl group, (m-methylbenzyl)aminocarbonyl group, (p-methylbenzyl)aminocarbonyl group, (o-vinylbenzyl)aminocarbonyl group, (m-vinylbenzyl)aminocarbonyl group, (p-vinylbenzyl)aminocarbonyl group, (o-methoxybenzyl)aminocarbonyl group, (m-methoxybenzyl)aminocarbonyl group, (p-methoxybenzyl)aminocarbonyl group, (o-vinyloxybenzyl)aminocarbonyl group, nyl group, (m-vinyloxybenzyl)aminocarbonyl group, (p-vinyloxybenzyl)aminocarbonyl group, (o-allyloxybenzyl)aminocarbonyl group, (m-allyloxybenzyl)aminocarbonyl group, (p-allyloxybenzyl)aminocarbonyl group, (o-methylcumyl)aminocarbonyl group, (m-methylcumyl)aminocarbonyl group, (p-methylcumyl)aminocarbonyl group, (o-methoxycumyl)aminocarbonyl group, (m-methoxycumyl)aminocarbonyl group, (p-methoxycumyl)aminocarbonyl group, and the like. Among these, any one of an (o-methylbenzyl)aminocarbonyl group, a (m-methylbenzyl)aminocarbonyl group, a (p-methylbenzyl)aminocarbonyl group, an (o-vinylbenzyl)aminocarbonyl group, a (m-vinylbenzyl)aminocarbonyl group, a (p-vinylbenzyl)aminocarbonyl group, an (o-methoxybenzyl)aminocarbonyl group, a (m-methoxybenzyl)aminocarbonyl group, a (p-methoxybenzyl)aminocarbonyl group, an (o-vinyloxybenzyl)aminocarbonyl group, a (m-vinyloxybenzyl)aminocarbonyl group, a (p-vinyloxybenzyl)aminocarbonyl group, an (o-allyloxybenzyl)aminocarbonyl group, a (m-allyloxybenzyl)aminocarbonyl group, or a (p-allyloxybenzyl)aminocarbonyl group is preferred.

[0051] Examples of the arylalkylsulfonylaminocarbonyl group having 8 to 49 carbon atoms, which may have a substituent, include the following: Among these, an arylalkylsulfonylaminocarbonyl group having 8 to 24 carbon atoms is preferred, from the viewpoint of improving compatibility with the leuco dye to increase color development sensitivity, and from the viewpoint of suppressing thermal motion of molecules to easily improve storage stability of the background portion.

[0052] Examples of unsubstituted arylalkylsulfonylaminocarbonyl groups having 8 to 49 carbon atoms include (benzylsulfonyl)aminocarbonyl groups, ((1-phenylethyl)sulfonyl)aminocarbonyl groups, ((2-phenylethyl)sulfonyl)aminocarbonyl groups, ((1-phenylpropyl)sulfonyl)aminocarbonyl groups, ((2-phenylpropyl)sulfonyl)aminocarbonyl groups, ((3-phenylpropyl)sulfonyl)aminocarbonyl groups, ((1-phenylbutyl)sulfonyl)aminocarbonyl groups, ((2-phenylbutyl)sulfonyl)aminocarbonyl groups, ((3-phenylbutyl)sulfonyl)aminocarbonyl groups, and ((4-phenylbutyl)sulfonyl)amino carbonyl group, (cumylsulfonyl)amino)carbonyl group, ((naphthylmethyl)sulfonyl)aminocarbonyl group, ((1-naphthylethyl)sulfonyl)aminocarbonyl group, ((2-naphthylethyl)sulfonyl)aminocarbonyl group, ((1-naphthylpropyl)sulfonyl)aminocarbonyl group, ((2-naphthylpropyl)sulfonyl)aminocarbonyl group, ((3-naphthylpropyl)sulfonyl)aminocarbonyl group, ((1-naphthylbutyl)sulfonyl)aminocarbonyl group, ((2-naphthylbutyl)sulfonyl)aminocarbonyl group, ((3-naphthylbutyl)sulfonyl)aminocarbonyl group, and ((4-naphthylbutyl)sulfonyl)aminocarbonyl group.Among these, any one of a (benzylsulfonyl)aminocarbonyl group, a ((1-phenylethyl)sulfonyl)aminocarbonyl group, a ((2-phenylethyl)sulfonyl)aminocarbonyl group, a ((1-phenylpropyl)sulfonyl)aminocarbonyl group, a ((2-phenylpropyl)sulfonyl)aminocarbonyl group, a ((3-phenylpropyl)sulfonyl)aminocarbonyl group, a (cumylsulfonyl)aminocarbonyl group, a ((naphthylmethyl)sulfonyl)aminocarbonyl group, a ((1-naphthylethyl)sulfonyl)aminocarbonyl group, a ((2-naphthylethyl)sulfonyl)aminocarbonyl group, a ((1-naphthylpropyl)sulfonyl)aminocarbonyl group, a ((2-naphthylpropyl)sulfonyl)aminocarbonyl group, or a ((3-naphthylpropyl)sulfonyl)aminocarbonyl group is preferred.

[0053] Examples of substituted arylalkylsulfonylaminocarbonyl groups having 8 to 49 carbon atoms include an ((o-methylbenzyl)sulfonyl)aminocarbonyl group, an ((m-methylbenzyl)sulfonyl)aminocarbonyl group, a ((p-methylbenzyl)sulfonyl)aminocarbonyl group, an ((o-vinylbenzyl)sulfonyl)aminocarbonyl group, an ((m-vinylbenzyl)sulfonyl)aminocarbonyl group, a ((p-vinylbenzyl)sulfonyl)aminocarbonyl group, an ((o-methoxybenzyl)sulfonyl)aminocarbonyl group, an ((m-methoxybenzyl)sulfonyl)aminocarbonyl group, a ((p-methoxybenzyl)sulfonyl)aminocarbonyl group, and an ((o-vinyloxybenzyl)sulfonyl)aminocarbonyl group. Examples thereof include an aminocarbonyl group, a ((m-vinyloxybenzyl)sulfonyl)aminocarbonyl group, a ((p-vinyloxybenzyl)sulfonyl)aminocarbonyl group, an ((o-allyloxybenzyl)sulfonyl)aminocarbonyl group, a ((m-allyloxybenzyl)sulfonyl)aminocarbonyl group, a ((p-allyloxybenzyl)sulfonyl)aminocarbonyl group, a ((o-methylcumyl)sulfonyl)aminocarbonyl group, a ((m-methylcumyl)sulfonyl)aminocarbonyl group, a ((p-methylcumyl)sulfonyl)aminocarbonyl group, a ((o-methoxycumyl)sulfonyl)aminocarbonyl group, a ((m-methoxycumyl)sulfonyl)aminocarbonyl group, and a ((p-methoxycumyl)sulfonyl)aminocarbonyl group.Among these, ((o-methylbenzyl)sulfonyl)aminocarbonyl group, ((m-methylbenzyl)sulfonyl)aminocarbonyl group, ((p-methylbenzyl)sulfonyl)aminocarbonyl group, ((o-vinylbenzyl)sulfonyl)aminocarbonyl group, ((m-vinylbenzyl)sulfonyl)aminocarbonyl group, ((p-vinylbenzyl)sulfonyl)aminocarbonyl group, ((o-methoxybenzyl)sulfonyl)aminocarbonyl group, ((m-methoxybenzyl)sulfonyl)aminocarbonyl group

[0046] It is preferable that the aminocarbonyl group is any one of a ((p-methoxybenzyl)sulfonyl)aminocarbonyl group, a ((o-vinyloxybenzyl)sulfonyl)aminocarbonyl group, a ((m-vinyloxybenzyl)sulfonyl)aminocarbonyl group, a ((p-vinyloxybenzyl)sulfonyl)aminocarbonyl group, a ((o-allyloxybenzyl)sulfonyl)aminocarbonyl group, a ((m-allyloxybenzyl)sulfonyl)aminocarbonyl group, and a ((p-allyloxybenzyl)sulfonyl)aminocarbonyl group.

[0054] From the viewpoint of improving the compatibility with the leuco dye to increase the color development sensitivity, and from the viewpoint of suppressing the thermal motion of molecules to easily improve the storage stability of the background portion, in formula (1), it is preferable that R or R is a hydrogen atom, and it is more preferable that R is a hydrogen atom.

[0055] Formula (1) is preferably the following (1A), and more preferably the following (1B).

[0056] (1A): R1 is a hydrogen atom; R2 is any one selected from the group consisting of an optionally substituted alkylcarbonyl group having 2 to 18 carbon atoms, an optionally substituted alkylaminocarbonyl group having 2 to 18 carbon atoms, an optionally substituted alkylsulfonylaminocarbonyl group having 2 to 18 carbon atoms, an optionally substituted phenylaminocarbonyl group, an optionally substituted phenylsulfonylaminocarbonyl group, an optionally substituted benzoyl group, and an optionally substituted naphthoyl group; and R3 is any one selected from the group consisting of an optionally substituted phenylaminocarbonyl group, an optionally substituted phenylsulfonylaminocarbonyl group, an optionally substituted arylalkylaminocarbonyl group having 8 to 24 carbon atoms, and an optionally substituted arylalkylsulfonylaminocarbonyl group having 8 to 24 carbon atoms.

[0057] (1B): R1 is a hydrogen atom; R2 is any one selected from the group consisting of an optionally substituted alkylcarbonyl group having 6 to 18 carbon atoms, an optionally substituted alkylaminocarbonyl group having 6 to 18 carbon atoms, an optionally substituted phenylaminocarbonyl group, an optionally substituted phenylsulfonylaminocarbonyl group, an optionally substituted benzoyl group, and an optionally substituted naphthoyl group; and R3 is an optionally substituted phenylaminocarbonyl group or an optionally substituted phenylsulfonylaminocarbonyl group.

[0058] The compound represented by formula (1) has isomers, and there are compounds represented by the following formulas (1-1), (1-2), (1-3), and (1-4). From the viewpoint of structural stability in consideration of steric hindrance, at least one of the compound represented by formula (1-1) and the compound represented by formula (1-2) is preferred.

[0059]

[0060]

[0061]

[0062]

[0063] In formulas (1-1) to (1-4), R1 to R3 have the same meanings as R1 to R3 in formula (1), respectively.

[0064] [Thermal Recording Material] The thermal recording material of the present invention is a thermal recording material having a support and a thermal recording layer provided on the support, and the thermal recording layer contains the color developer of the present invention. In the present invention, the "thermal recording material" refers to any material having a thermal recording layer on a support, and the material may be in the form of paper, film, synthetic paper, card, etc. The thermal recording material of the present invention has a thermal recording layer on a support, but may also have a protective layer, under layer, back layer, intermediate layer, etc., as described below, if necessary. Here, "on the support" refers to at least one side of the support, and typically refers to one side. Furthermore, "on the support" means that the layer is present on at least a portion of the support.

[0065] [Thermosensitive Recording Layer] The thermosensitive recording material of the present invention has a thermosensitive recording layer containing the color developer of the present invention. The thermosensitive recording layer may contain, in addition to the color developer of the present invention, a leuco dye, a color developer other than the compound represented by formula (1), a sensitizer, a stabilizer, a binder, a crosslinking agent, a pigment, a lubricant, and other additives.

[0066] <Leuco Dye> In the present invention, the thermosensitive recording layer preferably contains a leuco dye. Leuco dyes are typically basic, and any leuco dyes known in the art for pressure-sensitive or thermosensitive recording paper can be used. Specific examples of leuco dyes include triphenylmethane-based leuco dyes, fluoran-based leuco dyes, fluorene-based leuco dyes, and divinyl-based leuco dyes. Specific examples of representative colorless or pale-colored dyes (dye precursors) are shown below. These leuco dyes (leuco dye precursors) may be used alone or in combination of two or more. The leuco dye is preferably used in an amount of 10 to 200 parts by weight, more preferably 15 to 150 parts by weight, and even more preferably 20 to 100 parts by weight, per 100 parts by weight of the developer.

[0067] Examples of triphenylmethane leuco dyes include 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone); 3,3-bis(p-dimethylaminophenyl)phthalide (also known as malachite green lactone); and the like.

[0068] Examples of fluoran leuco dyes include 3-diethylamino-6-methylfluoran; 3-diethylamino-6-methyl-7-anilinofluoran; 3-diethylamino-6-methyl-7-(o,p-dimethylanilino)fluoran; 3-diethylamino-6-methyl-7-chlorofluoran; 3-diethylamino-6-methyl-7-(m-trifluoromethylanilino)fluoran; 3-diethylamino-6-methyl-7-(o-chloroanilino)fluoran; and 3-diethylamino-6-methyl-7-(p-chloroanilino)fluoran. ; 3-diethylamino-6-methyl-7-(o-fluoroanilino)fluoran; 3-diethylamino-6-methyl-7-(m-methylanilino)fluoran; 3-diethylamino-6-methyl-7-octylanilinofluoran; 3-diethylamino-6-methyl-7-octylaminofluoran; 3-diethylamino-6-methyl-7-benzylaminofluoran; 3-diethylamino-6-methyl-7-dibenzylaminofluoran; 3-diethylamino-6-chloro-7-methylfluoran; 3-diethylamino-6-chloro -7-anilinofluoran; 3-diethylamino-6-chloro-7-p-methylanilinofluoran; 3-diethylamino-6-ethoxyethyl-7-anilinofluoran; 3-diethylamino-7-methylfluoran; 3-diethylamino-7-chlorofluoran; 3-diethylamino-7-(m-trifluoromethylanilino)fluoran; 3-diethylamino-7-(o-chloroanilino)fluoran; 3-diethylamino-7-(p-chloroanilino)fluoran; 3-diethylamino-7-(o-fluoroanilino)fluoran fluoran; 3-diethylamino-benzo[a]fluoran; 3-diethylamino-benzo[c]fluoran; 3-dibutylamino-6-methyl-fluoran; 3-dibutylamino-6-methyl-7-anilinofluoran; 3-dibutylamino-6-methyl-7-(o,p-dimethylanilino)fluoran; 3-dibutylamino-6-methyl-7-(o-chloroanilino)fluoran; 3-dibutylamino-6-methyl-7-(p-chloroanilino)fluoran; 3-dibutylamino-6-methyl-7-(o-fluoroanilino)fluoran;3-dibutylamino-6-methyl-7-(m-trifluoromethylanilino)fluoran; 3-dibutylamino-6-methyl-chlorofluoran; 3-dibutylamino-6-ethoxyethyl-7-anilinofluoran; 3-dibutylamino-6-chloro-7-anilinofluoran; 3-dibutylamino-6-methyl-7-p-methylanilinofluoran; 3-dibutylamino-7-(o-chloroanilino)fluoran; 3-dibutylamino-7-(o-fluoroanilino)fluoran; 3-di-pentylamino-6-methyl-7-anilinofluoran ; 3-di-pentylamino-6-methyl-7-(p-chloroanilino)fluoran; 3-di-pentylamino-7-(m-trifluoromethylanilino)fluoran; 3-di-pentylamino-6-chloro-7-anilinofluoran; 3-di-pentylamino-7-(p-chloroanilino)fluoran; 3-pyrrolidino-6-methyl-7-anilinofluoran; 3-piperidino-6-methyl-7-anilinofluoran; 3-(N-methyl-N-propylamino)-6-methyl-7-anilinofluoran; 3-(N-methyl-N-cyclohexylamino) -6-methyl-7-anilinofluoran; 3-(N-ethyl-N-cyclohexylamino)-6-methyl-7-anilinofluoran; 3-(N-ethyl-N-xylamino)-6-methyl-7-(p-chloroanilino)fluoran; 3-(N-ethyl-p-toluidino)-6-methyl-7-anilinofluoran; 3-(N-ethyl-N-isoamylamino)-6-methyl-7-anilinofluoran; 3-(N-ethyl-N-isoamylamino)-6-chloro-7-anilinofluoran; 3-(N-ethyl-N-tetrahydrofurfurylamino)-6- Methyl-7-anilinofluoran; 3-(N-ethyl-N-isobutylamino)-6-methyl-7-anilinofluoran; 3-(N-ethyl-N-ethoxypropylamino)-6-methyl-7-anilinofluoran; 3-cyclohexylamino-6-chlorofluoran; 2-(4-oxahexyl)-3-dimethylamino-6-methyl-7-anilinofluoran; 2-(4-oxahexyl)-3-diethylamino-6-methyl-7-anilinofluoran; 2-(4-oxahexyl)-3-dipropylamino-6-methyl-7-anilinofluoran;2-Methyl-6-p-(p-dimethylaminophenyl)aminoanilinofluoran; 2-Methoxy-6-p-(p-dimethylaminophenyl)aminoanilinofluoran; 2-Chloro-3-methyl-6-p-(p-phenylaminophenyl)aminoanilinofluoran; 2-Chloro-6-p-(p-dimethylaminophenyl)aminoanilinofluoran; 2-Nitro-6-p-(p-diethylaminophenyl)aminoanilinofluoran; 2-Amino-6-p-(p-diethylaminophenyl)aminoanilinofluoran; 2-Diethylamino-6-p-(p-diethylaminophenyl)aminoanilinofluoran; 2-Phenyl Examples thereof include 2-benzyl-6-p-(p-phenylaminophenyl)aminoanilinofluoran; 2-hydroxy-6-p-(p-phenylaminophenyl)aminoanilinofluoran; 3-methyl-6-p-(p-dimethylaminophenyl)aminoanilinofluoran; 3-diethylamino-6-p-(p-diethylaminophenyl)aminoanilinofluoran; 3-diethylamino-6-p-(p-dibutylaminophenyl)aminoanilinofluoran; 2,4-dimethyl-6-[(4-dimethylamino)anilino]fluoran, and the like.

[0069] Examples of fluorene-based leuco dyes include 3,6,6'-tris(dimethylamino)spiro[fluorene-9,3'-phthalide]; 3,6,6'-tris(diethylamino)spiro[fluorene-9,3'-phthalide]; and the like.

[0070] Examples of divinyl leuco dyes include 3,3-bis[2-(p-dimethylaminophenyl)-2-(p-methoxyphenyl)ethenyl]-4,5,6,7-tetrabromophthalide; 3,3-bis[2-(p-dimethylaminophenyl)-2-(p-methoxyphenyl)ethenyl]-4,5,6,7-tetrachlorophthalide; 3,3-bis[1,1-bis(4-pyrrolidinophenyl)ethylene-2-yl]-4,5,6,7-tetrabromophthalide; and 3,3-bis[1-(4-methoxyphenyl)-1-(4-pyrrolidinophenyl)ethylene-2-yl]-4,5,6,7-tetrachlorophthalide.

[0071] Other leuco dyes include 3-(4-diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide; 3-(4-diethylamino-2-ethoxyphenyl)-3-(1-octyl-2-methylindol-3-yl)-4-azaphthalide; 3-(4-cyclohexylethylamino-2-methoxyphenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide; 3,3-bis(1-ethyl-2-methylindol-3-yl)phthalide; 3,6-bis(diethylamino)fluoran-γ-(3′-nitro)anilinolactam; 3, Examples include 6-bis(diethylamino)fluoran-γ-(4′-nitro)anilinolactam; 1,1-bis[2′,2′,2″,2″-tetrakis-(p-dimethylaminophenyl)-ethenyl]-2,2-dinitrileethane; 1,1-bis[2′,2′,2″,2″-tetrakis-(p-dimethylaminophenyl)-ethenyl]-2-β-naphthoylethane; 1,1-bis[2′,2′,2″,2″-tetrakis(p-dimethylaminophenyl)ethenyl]-2,2-diacetylethane; and bis[2,2,2′,2′-tetrakis(p-dimethylaminophenyl)ethenyl]-methylmalonic acid dimethyl ester. Among these, 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide [also known as crystal violet lactone], 3-diethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-octylaminofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, and 3-(N-ethyl-N-isoamylamino)-6-methyl-7-anilinofluoran are preferred.

[0072] <Other Color Developers> The thermosensitive recording layer may contain a color developer other than Compound (I) of the present invention (hereinafter referred to as "other color developers") within a range that does not impair the effects of the present invention. Any other color developer known in the field of conventional pressure-sensitive or thermosensitive recording paper can be used as the other color developer, and there are no particular limitations, but an electron-accepting color developer is preferred. One type of other color developer may be used alone, or two or more types may be used in combination. When other color developers are used, the amounts used are preferably Compound (I):other color developer = 99:1 to 30:70 parts by mass, more preferably Compound (I):other color developer = 99:1 to 50:50 parts by mass, and even more preferably Compound (I):other color developer = 99:1 to 60:40 parts by mass, based on 100 parts by mass of the total amount of color developers.

[0073] By using other color developers, it is possible to obtain an excellent heat-sensitive recording material that maintains high color development sensitivity and further improves image preservation properties such as heat resistance, moisture resistance, and water resistance.

[0074] Other color developers include bisphenol compounds, urea compounds, novolac-type phenol compounds, and amino acid derivative compounds.

[0075] Examples of bisphenol compounds include 4,4'-isopropylidenediphenol, 2,2'-bis(4-hydroxy-3-methylphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 4,4'-dihydroxydiphenyl sulfide, di(4-hydroxy-3-methylphenyl)sulfide, 2,2'-thiobis(3-tert-octylphenol), 2,2'-thiobis(4-tert-octylphenol), 4,4'-dihydroxydiphenyl sulfone, and 2,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-propoxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, 4-hydroxy-4'-allyloxydiphenyl sulfone, bis(3-allyl-4-hydroxyphenyl)sulfone, 4-hydroxyphenyl-4'-benzyloxyphenyl sulfone, 3,4-dihydroxyphenyl-4'-methylphenyl sulfone, 2,4-bis(phenylsulfonyl)phenol, bisphenol sulfone crosslinked compounds described in Japanese Patent No. 3913820, and bisphenol sulfone derivatives described in Japanese Patent No. 4004289.

[0076] Examples of urea compounds include 4,4'-bis(3-(phenoxycarbonylamino)methylphenylureido)diphenyl sulfone, N-(p-toluenesulfonyl)-N'-(3-p-toluenesulfonyloxyphenyl)urea described in Japanese Patent No. 4601174, 4,4'-bis(3-tosylureido)diphenylmethane described in JP-A-2011-105638, N-[2-(3-phenylureido)phenyl]benzenesulfonamide described in JP-A-2016-165835, N-[2-(acetoxy)phenyl]-N'-phenylurea, N-[3-(acetoxy)phenyl]-N'-phenylurea, N-[2-(benzoyloxy)phenyl]-N'-phenylurea, and N-[3-(benzoyloxy)phenyl]- N'-phenylurea, [3- (3-phenylureido) phenyl] = 4-methylbenzenesulfonate described in Japanese Patent Application No. 2023-515875, 4-methylphenyl = [3- [ [ (phenylamino) carbonyl] amino] benzenesulfonate] described in WO2022 / 045287, N, N'-bis (3- [ {4-methylphenyl} sulfonylamino] phenyl) urea described in Japanese Patent Application No. 2021-131277, N, N'-di - [3- (p- toluenesulfonyloxy) phenyl] urea described in Japanese Patent Application No. 2019-539154, 3- [ (phenylcarbamoyl) amino] phenyl-4-methylbenzenesulfonate described in Japanese Patent Application No. 2015-254099, N, N'-di [3- (p- toluenesulfonyl) oxy] phenyl urea described in Japanese Patent Application No. 2017-167444, and the like.

[0077] Examples of novolak-type phenolic compounds include phenol-formalin condensates described in WO 02 / 098674.

[0078] Examples of the amino acid derivative compounds include N-(m-tolylaminocarbonyl)-phenylalanine, N-(p-toluenesulfonyl)-phenylalanine, N-(benzyloxycarbonyl)-valine, N-(m-tolylaminocarbonyl)-methionine, N-(m-tolylaminocarbonyl)-tyrosine, N-(m-tolylaminocarbonyl)-phenylglycine, N-(m-tolylaminocarbonyl)-valine, and N-( and amino acid derivatives such as N-(m-tolylaminocarbonyl)-cysteine-S-benzyl, N-(m-tolylaminocarbonyl)-β-alanine, N-phenylaminothiocarbonyl-glycylglycine, N-(p-toluenesulfonylaminocarbonyl)-phenylalanine-methyl ester, N-(p-toluenesulfonyl)-β-alanine, N-(p-tolylaminocarbonyl)-methionine, and N-(phenylaminocarbonyl)-methionine.

[0079] In addition to the compounds listed above, inorganic acidic substances such as activated clay, attapulgite, colloidal silica, and aluminum silicate, hydroquinone monobenzyl ether, benzyl 4-hydroxybenzoate, aminobenzenesulfonamide derivatives described in JP-A-8-59603, bis(4-hydroxyphenylthioethoxy)methane, 1,5-di(4-hydroxyphenylthio)-3-oxapentane, butyl bis(p-hydroxyphenyl)acetate, methyl bis(p-hydroxyphenyl)acetate, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 1,4-bis[α-methyl-α-(4'-hydroxyphenyl)ethyl]benzene, 1,3-bis[α-methyl-α-(4'-hydroxyphenyl)ethyl]benzene, and compounds disclosed in WO 02 / 081229 are also usable. and the compounds described in JP-A-2002-301873, thiourea compounds such as N,N'-di-m-chlorophenylthiourea, aromatic carboxylic acids such as p-chlorobenzoic acid, stearyl gallate, zinc bis[4-(octyloxycarbonylamino)salicylate] dihydrate, 4-[2-(p-methoxyphenoxy)ethyloxy]salicylic acid, 4-[3-(p-tolylsulfonyl)propyloxy]salicylic acid, and 5-[p-(2-p-methoxyphenoxyethoxy)cumyl]salicylic acid, and salts of these aromatic carboxylic acids with polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, and nickel, as well as antipyrine complexes of zinc thiocyanate and complex zinc salts of terephthalaldehyde acid and other aromatic carboxylic acids. Examples include metal chelate complexes of higher fatty acid metal double salts and polyvalent hydroxy aromatic compounds, etc., as described in JP-A-10-258577.

[0080] Among the above-mentioned other color developers, 4,4'-dihydroxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-propoxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, 4-hydroxy-4'-allyloxydiphenyl sulfone, bis(3-allyl-4-hydroxyphenyl)sulfone, 4,4'-isopropylidenediphenol, 2,2'-bis(4-hydroxy-3-methylphenyl)propane, diphenyl sulfone crosslinked compounds described in Japanese Patent No. 3913820, diphenyl sulfone derivatives described in Japanese Patent No. 4004289, phenol-formalin condensates described in International Publication No. 02 / 098674, 4,4'-bis(3-(phenoxycarbonylamino)methylphenylureido)diphenyl sulfone, N-(p-toluenesulfonyl)-N'-( 3-p-toluenesulfonyloxyphenyl)urea, 4,4'-bis(3-tosylureido)diphenylmethane described in JP 2011-105638 A, N-[2-(3-phenylureido)phenyl]benzenesulfonamide described in JP 2016-165835 A, N-(m-tolylaminocarbonyl)-phenylalanine and N-(m-tolylaminocarbonyl)-methionine described in WO 2017 / 047572 A N,N'-bis(3-[{4-methylphenyl}sulfonylamino]phenyl)urea described in Japanese Patent Application No. 2021-131277, N,N'-bis(3-[{4-methylphenyl}sulfonylamino]phenyl)urea described in Japanese Patent Application No. 2019-539154, N,N'-bis(3-[{4-methylphenyl}sulfonylamino]phenyl)urea described in Japanese Patent Application No. 2023-515875, N,N'-bis(3-[{4-methylphenyl}sulfonylamino]phenyl)urea described in Japanese Patent Application No. 2019-539154,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea, N-(m-tolylaminocarbonyl)-phenylalanine described in WO 2017 / 047572, N-(p-toluenesulfonyl)-phenylalanine, N-(benzyloxycarbonyl)-valine, N-(m-tolylaminocarbonyl)-methionine, N-(m-tolylaminocarbonyl)-tyrosine, N-(m-tolylaminocarbonyl)-phenylglycine, N-(m-tolylaminocarbonyl)-valine, N-(m-tolylamino carbonyl)-cysteine-S-benzyl, N-(m-tolylaminocarbonyl)-β-alanine, N-phenylaminothiocarbonyl-glycylglycine, N-(p-toluenesulfonylaminocarbonyl)-phenylalanine-methyl ester, N-(p-toluenesulfonyl)-β-alanine, N-(p-tolylaminocarbonyl)-methionine, N-(phenylaminocarbonyl)-methionine, 3-[(phenylcarbamoyl)amino]phenyl-4-methylbenzene described in Japanese Patent Application No. 2015-254099 Sulfonates, and N,N'-di[3-(p-toluenesulfonyl)oxy]phenylurea described in Japanese Patent Application No. 2017-167444 are preferred, as well as 4,4'-dihydroxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-propoxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, 4-hydroxy-4'-allyloxydiphenyl sulfone, bis(3-allyl-4-hydroxyphenyl) sulfone, 2,2'-bis(4-hydroxy-3-methyl) diphenyl)propane, diphenyl sulfone bridged compounds described in Japanese Patent No. 3913820, diphenyl sulfone derivatives described in Japanese Patent No. 4004289, phenol-formalin condensates described in International Publication No. 02 / 098674, 4,4'-bis(3-(phenoxycarbonylamino)methylphenylureido)diphenyl sulfone, N-(p-toluenesulfonyl)-N'-(3-p-toluenesulfonyloxyphenyl)urea described in Japanese Patent No. 4601174, 4,4'-bis(3-(phenoxycarbonylamino)methylphenylureido)diphenyl sulfone, N-(p-toluenesulfonyl)-N'-(3-p-toluenesulfonyloxyphenyl)urea described in Japanese Patent No. 2011-105638,4'-bis(3-tosylureido)diphenylmethane, N-[2-(3-phenylureido)phenyl]benzenesulfonamide described in JP 2016-165835 A, N-(m-tolylaminocarbonyl)-phenylalanine and N-(m-tolylaminocarbonyl)-methionine described in WO 2017 / 047572, [3-(3-phenylureido)phenyl]=4-methylbenzenesulfonate described in Japanese Patent Application No. 2023-515875, 4-methylphenyl=[3-[[(phenylamino) )carbonyl]amino]benzenesulfonate], N,N'-bis(3-[{4-methylphenyl}sulfonylamino]phenyl)urea described in Japanese Patent Application No. 2021-131277, N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea described in Japanese Patent Application No. 2019-539154, 3-[(phenylcarbamoyl)amino]phenyl-4-methylbenzenesulfonate described in Japanese Patent Application No. 2015-254099, and N,N'-di[3-(p-toluenesulfonyl)oxy]phenylurea described in Japanese Patent Application No. 2017-167444 are more preferred. By using these, it is possible to improve the image storage stability (heat resistance, plasticizer resistance, humidity resistance, water resistance, grease resistance) while maintaining the color development sensitivity of the thermal recording material.

[0081] <Sensitizer> In the thermal recording material of the present invention, a known sensitizer may be used in the thermal recording layer. From the viewpoint of enabling color development with lower energy, it is preferable that the thermal recording layer contains a sensitizer. There are no particular limitations on the sensitizer, but examples thereof include 1,2-di-(3-methylphenoxy)ethane, 2-benzyloxynaphthalene, fatty acid amides having 10 to 21 carbon atoms (e.g., stearic acid amide, palmitic acid amide, etc.), ethylene bisamide, montanic acid wax, polyethylene wax, p-benzylbiphenyl, diphenyl sulfone, 4-biphenyl-p-tolyl ether, m-terphenyl, 1,2-diphenoxyethane, dibenzyl oxalate, di(p-chlorobenzyl oxalate), di(p-methylbenzyl oxalate), dibenzyl terephthalate, and p-benzyloxybenzoate. Examples of suitable benzoates that can be used include benzyl benzoate, di-p-tolyl carbonate, phenyl-α-naphthyl carbonate, 1,4-diethoxynaphthalene, 1-hydroxy-2-naphthoic acid phenyl ester, o-xylene-bis-(phenyl ether), 4-(m-methylphenoxymethyl)biphenyl, 4,4′-ethylenedioxy-bis-benzoic acid dibenzyl ester, dibenzoyloxymethane, 1,2-di(3-methylphenoxy)ethylene, bis[2-(4-methoxy-phenoxy)ethyl]ether, methyl p-nitrobenzoate, and phenyl p-toluenesulfonate. Among these, 1,2-di-(3-methylphenoxy)ethane, 1,2-diphenoxyethane, fatty acid amides having 10 to 21 carbon atoms (e.g., stearic acid amide, palmitic acid amide, etc.), 2-benzyloxynaphthalene, diphenyl sulfone, p-toluenesulfonamide, and oxalic acid-di-p-methylbenzyl ester are preferred, and 1,2-di-(3-methylphenoxy)ethane, 1,2-diphenoxyethane, and 2-benzyloxynaphthalene, which exhibit high color-developing sensitivity even at low energy, are particularly preferred. These sensitizers may be used alone or in combination of two or more. When a sensitizer is used, the amount used is preferably 25 to 250 parts by mass, more preferably 50 to 150 parts by mass, per 100 parts by mass of Compound (I).

[0082] <Stabilizer> In the present invention, a stabilizer may be used in the thermosensitive recording layer to improve the image storage stability of the thermosensitive recording material. A stabilizer refers to a substance that has the effect of improving the image storage stability. Examples of stabilizers include hindered phenol compounds, ultraviolet absorbers (e.g., benzophenone compounds, triazole compounds), antioxidants, etc. Among these, hindered phenol compounds are preferred in terms of improving the image storage stability (heat resistance, moisture resistance, water resistance, plasticizer resistance, etc.) of the recorded area.

[0083] The hindered phenol compound is a compound having typically 1 to 15, preferably 2 to 6, hydroxyphenyl groups per molecule. The molecular weight of the hindered phenol compound is typically 200 to 2,000, preferably 250 to 1,800, more preferably 300 to 1,500. The melting point of the hindered phenol compound is preferably 100° C. to 300° C.

[0084] Furthermore, in at least one of the hydroxyphenyl groups contained in the hindered phenol compound, when the position of the phenolic hydroxyl group is taken as the 1st position, it is preferable that the carbon atom at either the 2nd or 6th position is bonded to a hydrogen atom (i.e., there is no substituent at the 2nd or 6th position).

[0085] Specific examples of the hindered phenol compound include tris(hydroxyphenyl)alkanes and 1,1,3-tris-substituted butane compounds described in JP-B No. 39-4469 or JP-A No. 56-40629, and these may be used in combination of two or more.

[0086] The hindered phenol compounds may be used alone or in combination of two or more. When a hindered phenol compound is used in the heat-sensitive recording material of the present invention, the content thereof is preferably 1 to 100 parts by mass, more preferably 1 to 70 parts by mass, and even more preferably 1 to 50 parts by mass, per 100 parts by mass of compound (1). If the content of the hindered phenol compound is less than this range, the moisture resistance, water resistance, and heat resistance of the recorded area may be reduced, and color development in blank areas due to heating may not be suppressed. If the content is greater than this range, the color development sensitivity may be reduced, and the plasticizer resistance of the recorded area may be reduced.

[0087] <Binder> It is preferable to use a binder to form the thermal recording layer. Examples of the binder include fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, acetoacetylated polyvinyl alcohol, carboxy-modified polyvinyl alcohol, amide-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, butyral-modified polyvinyl alcohol, olefin-modified polyvinyl alcohol, nitrile-modified polyvinyl alcohol, pyrrolidone-modified polyvinyl alcohol, silicone-modified polyvinyl alcohol, other modified polyvinyl alcohols, hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, polystyrene, styrene copolymers such as styrene-maleic anhydride copolymer and styrene-butadiene copolymer, cellulose derivatives such as ethyl cellulose and acetyl cellulose, casein, gum arabic, oxidized starch, etherified starch, dialdehyde starch, esterified starch, polyvinyl chloride, polyvinyl acetate, polyacrylamide, polyacrylic acid ester, polyvinyl butyral, polyamide resin, silicone resin, petroleum resin, terpene resin, ketone resin, and coumarone resin. The amount of binder used is suitably about 5 to 25% by mass of the solid content of the heat-sensitive recording layer.

[0088] The binder is generally used as a solution, emulsion, dispersion, paste, or a combination thereof. Examples of the solvent for the solution, emulsion, or dispersion, or the medium for the paste, include water, alcohol, ketones, esters, and hydrocarbons.

[0089] <Crosslinking Agent> In the heat-sensitive recording material of the present invention, a crosslinking agent may be used in the heat-sensitive recording layer. Examples of crosslinking agents include glyoxal, methylol melamine, melamine formaldehyde resin, melamine urea resin, polyamine epichlorohydrin resin, polyamide epichlorohydrin resin, potassium persulfate, ammonium persulfate, sodium persulfate, ferric chloride, magnesium chloride, borax, boric acid, alum, and ammonium chloride. When a crosslinking agent is used, the amount used is preferably 0.5 to 500 parts by mass per 100 parts by mass of compound (I).

[0090] <Pigment> In the heat-sensitive recording material of the present invention, a pigment may be used in the heat-sensitive recording layer. Examples of the pigment include inorganic or organic pigments such as silica (excluding colloidal silica), calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc, titanium oxide, and aluminum hydroxide. When a pigment is used, the amount used is preferably 25 to 1,000 parts by mass per 100 parts by mass of compound (I).

[0091] <Lubricant> In the heat-sensitive recording material of the present invention, a lubricant may be used in the heat-sensitive recording layer. Examples of lubricants include fatty acid metal salts such as zinc stearate and calcium stearate, waxes, and silicone resins. When a lubricant is used, the amount thereof is preferably 0.5 to 500 parts by mass per 100 parts by mass of compound (I).

[0092] <Other Additives> In the heat-sensitive recording material of the present invention, other additives may be used in the heat-sensitive recording layer. Examples of other additives include dispersants, antifoaming agents, fluorescent dyes, etc. When other additives are used, the amount used is preferably 0.5 to 500 parts by mass per 100 parts by mass of Compound (I).

[0093] From the viewpoints of the color development, image preservation, and mechanical performance of the thermal paper against printing devices, the thermal recording layer preferably contains a color developer, a leuco dye, a binder, a pigment, and a lubricant, more preferably 25 to 75 parts by mass of the leuco dye, 5 to 40 parts by mass of the binder, 100 to 500 parts by mass of the pigment, and 5 to 30 parts by mass of the lubricant, relative to 100 parts by mass of the color developer. Furthermore, from the viewpoints of improving the color development and image preservation of the thermal paper, the thermal recording layer preferably contains a color developer, a leuco dye, a binder, a pigment, a lubricant, a sensitizer, and a stabilizer, more preferably 25 to 75 parts by mass of the leuco dye, 5 to 30 parts by mass of the binder, 100 to 500 parts by mass of the pigment, 5 to 40 parts by mass of the lubricant, 25 to 200 parts by mass of the sensitizer, and 5 to 100 parts by mass of the stabilizer, relative to 100 parts by mass of the color developer.

[0094] [Support] The shape, structure, size, material, etc. of the support used in the thermal recording material of the present invention are not particularly limited and can be appropriately selected depending on the purpose. Examples of the shape of the support include sheet, roll, and flat plate. The support may have a single-layer structure or a laminated structure. The size of the support can be appropriately selected depending on the intended use of the thermal recording material. Examples of support materials include plastic film, synthetic paper, high-quality paper, waste paper pulp, recycled paper, one-side gloss paper, greaseproof paper, coated paper, art paper, cast-coated paper, lightly coated paper, resin-laminated paper, and release paper. A composite sheet combining these materials may also be used as the support.

[0095] The thickness of the support is not particularly limited and can be appropriately selected depending on the purpose, and is preferably 30 to 2,000 μm, more preferably 50 to 1,000 μm.

[0096] [Protective Layer] In the thermosensitive recording material of the present invention, a protective layer may be provided on the thermosensitive recording layer. Generally, providing a protective layer on the thermosensitive recording layer to improve the image storage stability of the thermosensitive recording material reduces the color development sensitivity. However, in the thermosensitive recording material of the present invention, since the highly sensitive compound (I) is used as a color developer, the sensitivity required for thermal paper can be maintained even when a protective layer is provided on the thermosensitive recording layer. The types and amounts of various components used in the protective layer are determined according to the required performance and recording suitability and are not particularly limited.

[0097] [Underlayer, Back Layer, and Intermediate Layer] In the thermosensitive recording material of the present invention, an underlayer mainly composed of a pigment and a binder may be provided between the support and the thermosensitive recording layer in order to further enhance color development sensitivity. Furthermore, in order to correct curling of the thermosensitive recording material of the present invention, a back layer may be provided on the side of the support opposite to the side on which the thermosensitive recording layer is located. One embodiment of the layers in the thermosensitive recording material of the present invention includes, but is not limited to, a layered configuration in the order of protective layer / thermosensitive recording layer / underlayer / support / back layer.

[0098] Furthermore, an intermediate layer may be formed between the support and the under layer, between the under layer and the thermosensitive recording layer, between the thermosensitive recording layer and the protective layer, and / or between the support and the back layer.

[0099] [Method for producing a thermal recording material] The thermal recording material of the present invention can be produced by, for example, applying a coating liquid containing a basic leuco dye and a color developer, and if necessary, other color developers, a hindered phenol compound, a sensitizer, etc., to at least a portion of at least one surface of a support and drying the coating liquid to form a thermal recording layer. This coating liquid can be applied according to well-known conventional techniques. There are no particular limitations on the coating means, and for example, an off-machine coater or an on-machine coater equipped with various coaters such as an air knife coater, a rod blade coater, a bent blade coater, a bevel blade coater, a roll coater, or a curtain coater can be used.

[0100] The coating liquid for forming the thermosensitive recording layer can be prepared by blending, for example, a color developer and, if necessary, a leuco dye, other color developers, a hindered phenol compound, a sensitizer, etc., and then atomizing the mixture to a particle size of several microns or less using a grinder such as a ball mill, attritor, or sand grinder, or an appropriate emulsifier, and then adding a binder, etc. to the mixture. Examples of solvents that can be used in this coating liquid include water and alcohol. The solid content of the coating liquid is usually 20 to 40% by mass.

[0101] The coating amount of the thermal recording layer can be appropriately selected depending on the composition and the application of the thermal recording material, but is usually 1 to 20 g / m2 in terms of dry mass. 2 , preferably 2 to 12 g / m 2 The range is.

[0102] From the viewpoint of the color development, image preservation, and mechanical performance of the thermal paper against printing devices, the coating liquid preferably contains a color developer, a leuco dye, a binder, a pigment, a lubricant, and water, and more preferably contains 25 to 75 parts by mass of the leuco dye, 5 to 40 parts by mass of the binder, 100 to 500 parts by mass of the pigment, and 5 to 30 parts by mass of the lubricant, relative to 100 parts by mass of the color developer, and the solids content is 14 to 25% by mass. Furthermore, from the viewpoint of improving the color development and image preservation properties of the thermal paper, it is preferable that the coating liquid contains a color developer, a leuco dye, a binder, a pigment, a lubricant, a sensitizer, a stabilizer, and water, and that the amounts of the leuco dye, binder, pigment, lubricant, sensitizer, stabilizer, and water are 25 to 75 parts by mass, 5 to 30 parts by mass, 100 to 500 parts by mass, lubricant, 5 to 40 parts by mass, sensitizer, 25 to 200 parts by mass, and stabilizer, relative to 100 parts by mass of the color developer, and that the solids content is 14 to 25% by mass.

[0103] Similarly to the above-mentioned thermosensitive recording layer, the protective layer, under layer, back layer, and intermediate layer can also be formed by applying and drying a coating liquid containing the constituent components thereof. Furthermore, the thermosensitive recording material of the present invention having each layer formed thereon may be subjected to a treatment known in the art (for example, smoothing treatment by supercalendering, etc.).

[0104] [Uses of the Thermal Recording Material] The thermal recording material of the present invention can be suitably used for applications such as paper, film, IC cards, and friction ballpoint pens.

[0105] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not changed.

[0106] In the following examples and comparative examples, Hakugin paper manufactured by Nippon Paper Industries Co., Ltd. was used as a support, and a thermosensitive recording layer (thermosensitive coloring layer) was formed on one side (smooth side) of the paper. In the following examples and comparative examples, "parts" and "%" mean "parts by mass" and "% by mass", respectively, unless otherwise specified.

[0107] Comparative Synthesis Example 1: Synthesis of 2-O-benzoyl-6-O-palmitoyl-L-ascorbic acid

[0108]

[0109] A three-neck flask equipped with a dropping funnel, thermometer, and reflux condenser was charged with 10.36 g of 6-O-palmyloyl-L-ascorbic acid, which was then dissolved in 4.67 g of triethylamine and 50.0 g of dimethylformamide. The reaction solution was adjusted to 30°C and stirred with a magnetic stirrer. While this was being stirred, 3.87 g of benzoyl chloride was added dropwise via the dropping funnel, and the mixture was stirred for 5 hours. After cooling to room temperature, 50.0 g of chloroform was added, followed by washing with water, dehydration with magnesium sulfate, and concentration under reduced pressure. The resulting crude product was dissolved in ethyl acetate and subjected to silica gel chromatography using heptane / ethyl acetate. The solvent was then distilled off, yielding 4.16 g of the target product as a white crystal.

[0110] Using a Melting Point System MP70 manufactured by Mettler Toledo, the target substance was heated at a rate of 10°C / min, and the temperature at which the substance was completely liquefied was visually read and taken as the melting point. The melting point was 119°C.

[0111] The chemical shifts (σ ppm) in the proton NMR spectrum (400 MHz) measured in deuterated DMSO solvent were as follows: σ: 0.844 (t, 3H, J = 6.0 Hz), 1.222 (s, 24H), 1.534 (m, 3H), 2.300 (t, 2H, J = 6.0 Hz), 4.020-4.092 (m, 2H), 5.012 (s, 1H), 7.587-8.083 (m, 5H).

[0112] Synthesis Example 1: Synthesis of 2-O-phenylaminocarbonyl-6-O-stearoyl-L-ascorbic acid

[0113]

[0114] Into a three-neck flask equipped with a dropping funnel, a thermometer, and a reflux condenser, 11.06 g of 6-O-stearoyl-L-ascorbic acid was placed and dissolved in 3.29 g of triethylamine and 50.0 g of dimethylformamide. The reaction solution was adjusted to 40°C and stirred with a magnetic stirrer, while 3.04 g of phenyl isocyanate was added dropwise using the dropping funnel, and the mixture was stirred for 3 hours. After cooling to room temperature, hydrochloric acid was added, and the mixture was extracted with dichloromethane and washed with water, and the precipitate was filtered to obtain 9.79 g of the target whitish-brown crystals.

[0115] Using a Melting Point System MP70 manufactured by Mettler Toledo, the target substance was heated at a rate of 10°C / min, and the temperature at which the substance was completely liquefied was visually read and taken as the melting point. The melting point was 148°C.

[0116] The chemical shifts (σ ppm) in the proton NMR spectrum (400 MHz) measured in deuterated DMSO solvent were as follows: σ: 0.836 (t, 3H, J = 7.0 Hz), 1.219 (s, 30H), 1.518 (m, 3H), 2.316 (t, 2H, J = 6.0 Hz), 4.075 (m, 3H), 4.923 (s, 1H), 5.515 (bs, 1H), 7.035 (t, 1H, J = 7.0 Hz), 7.310 (t, 2H, J = 7.0 Hz), 7.468 (d, 2H, J = 7.0 Hz), 10.181 (s, 1H).

[0117] [Coating liquid for thermosensitive recording layer] The following liquids A to E were prepared. Liquids A and B were wet-milled using a ready mill (RMB-02) manufactured by Imex Co., Ltd. until the average particle size of each component reached 0.5 μm. The average particle size here is the average size in a volume-based distribution, and was measured using a laser diffraction / scattering particle size distribution analyzer (Microtrac MT3000II) manufactured by Nikkiso Co., Ltd.

[0118] <Solution A> Compound of Synthesis Example 1: 9.0 parts Polyvinyl alcohol (10% aqueous solution): 10.0 parts Water: 81.0 parts

[0119] <Solution B> 3-dibutylamino-6-methyl-7-anilinofluoran (manufactured by Yamamoto Chemical Industries, Ltd., trade name "ODB-2"): 36.5 parts Polyvinyl alcohol (10% aqueous solution): 60.0 parts Water: 3.5 parts

[0120] <Liquid C> Calcium carbonate dispersion with 60% solids (manufactured by Okutama Kogyo Co., Ltd., product name "Tama Pearl (registered trademark) TP-123CS")

[0121] <Solution D> 36% zinc stearate dispersion (manufactured by Chukyo Yushi Co., Ltd., product name "Hydrin Z-8-36")

[0122] <Solution E> 10% aqueous solution of polyvinyl alcohol (10% aqueous solution of "GOHSENOL (registered trademark) NH-18", manufactured by Nippon Synthetic Co., Ltd.)

[0123] [Example 1] A coating liquid for the thermosensitive recording layer was prepared by mixing the respective liquids in the following ratios: Liquid A: 85.00 parts Liquid B: 10.00 parts Liquid C: 17.87 parts Liquid D: 6.00 parts Liquid E: 19.62 parts Next, the coating liquid for the thermosensitive recording layer was applied to one side (smooth side) of a paper support so that the dry mass of the thermosensitive recording layer would be 4 to 6 g / m2, and then dried (air dryer, 60°C, 2 minutes) to form a thermosensitive recording layer. The support on which the thermosensitive recording layer had been formed was then treated with a supercalender so that the smoothness would be 500 to 1000 seconds, to obtain a thermosensitive recording material. This was then calendered at 1 kgf / cm 2 The film was smoothed by applying a pressure of 1000 psi to obtain a heat-sensitive recording material.

[0124] Comparative Example 1 A thermal recording material was produced in the same manner as in Example 1, except that the compound in Synthesis Example 1 for Solution A was changed to 2-O-α-D-glucopyranosyl-L-ascorbic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and the components of Solution A were mixed and dissolved by stirring to prepare Solution A.

[0125] Comparative Example 2 A heat-sensitive recording material was produced in the same manner as in Example 1, except that the compound in Synthesis Example 1 of Solution A was changed to 6-O-stearoyl-L-ascorbic acid (manufactured by Tokyo Chemical Industry Co., Ltd.).

[0126] Comparative Example 3 A heat-sensitive recording material was produced in the same manner as in Example 1, except that the compound in Synthesis Example 1 of Solution A was changed to 2,6-O-dipalmitoyl-L-ascorbic acid (manufactured by Tokyo Chemical Industry Co., Ltd.).

[0127] Comparative Example 4 A heat-sensitive recording material was produced in the same manner as in Example 1, except that the compound in Synthesis Example 1 in Solution A was changed to the compound in Comparative Synthesis Example 1.

[0128] [Color development sensitivity] Gradation patterns were printed using a thermal printer (TH-M2 / PX) manufactured by Okura Electric Co., Ltd., and the image density at an applied energy of 0.396 mJ / dot was measured using an eXact densitometer manufactured by X-Rite Corporation. The results are shown in Table 1. Note that in this test, a higher image density value indicates better color development sensitivity.

[0129] [Heat Resistance of Non-Printed Area] A thermal recording material was printed with a checkerboard pattern at an applied energy of 0.396 mJ / dot using a thermal printer (TH-M2 / PS) manufactured by Okura Electric Co., Ltd., and left to stand in an environment at a temperature of 80°C for 24 hours, after which the image density of the non-printed area was measured using an eXact densitometer manufactured by X-Rite Corporation. The image densities after the test are shown in Table 1. Note that in this test, the smaller the image density value, the better the heat resistance.

[0130]

[0131] As is clear from the results in Table 1, Example 1, which used the compound of the present invention as a color developer, exhibited improved color development sensitivity and heat resistance in non-printed areas compared to Comparative Examples 1 to 4, which used conventional color developers. This is believed to be due to the introduction of a highly hydrophobic functional group into ascorbic acid, which increased compatibility with the leuco dye and facilitated reaction with the leuco dye, thereby improving color development sensitivity. Furthermore, the compound of Example 1 has a higher melting point due to the introduction of an N-H moiety at the 2-O site of ascorbic acid, making it difficult for the non-printed areas to melt and develop color even when heated to 80°C. This is believed to have improved the heat resistance of the non-printed areas. Furthermore, the hydroxyl group at the 3-position of ascorbic acid binds to the leuco dye in a chelate-like manner at the N-H site, increasing binding reactivity and leading to improved sensitivity.

[0132] As described above, by using a color developer consisting of a compound corresponding to formula (1), it is possible to provide a well-balanced thermal recording material that is excellent in both color development sensitivity and heat resistance of non-printed areas.

Claims

1. A color developer comprising a compound represented by the following formula (1): In formula (1), any one of R1, R2, and R3 is a hydrogen atom, and (i) when R1 is a hydrogen atom, R2 and R3 may be the same or different independently from each other, R2 is any one selected from the group consisting of an aliphatic hydrocarbon group having 1 to 30 carbon atoms which may have a substituent, an alkylcarbonyl group having 2 to 31 carbon atoms which may have a substituent, an alkylaminocarbonyl group having 2 to 31 carbon atoms which may have a substituent, an alkylsulfonylaminocarbonyl group having 2 to 31 carbon atoms which may have a substituent, a phenyl group which may have a substituent, a naphthyl group which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, a benzoyl group which may have a substituent, a naphthoyl group which may have a substituent, an arylalkyl group having 7 to 48 carbon atoms which may have a substituent, an arylalkylcarbonyl group having 8 to 49 carbon atoms which may have a substituent, an arylalkylaminocarbonyl group having 8 to 49 carbon atoms which may have a substituent, and an arylalkylsulfonylaminocarbonyl group having 8 to 49 carbon atoms which may have a substituent, R3 represents any one selected from the group consisting of an alkylaminocarbonyl group having 2 to 31 carbon atoms which may have a substituent, an alkylsulfonylaminocarbonyl group having 2 to 31 carbon atoms which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, an arylalkylaminocarbonyl group having 8 to 49 carbon atoms which may have a substituent, and an arylalkylsulfonylaminocarbonyl group having 8 to 49 carbon atoms which may have a substituent, (ii) when R2 is a hydrogen atom, R1 and R3 may be the same or independently different,R1 and R3 each represent any one selected from the group consisting of an aliphatic hydrocarbon group having 1 to 30 carbon atoms which may have a substituent, an alkylcarbonyl group having 2 to 31 carbon atoms which may have a substituent, an alkylaminocarbonyl group having 2 to 31 carbon atoms which may have a substituent, an alkylsulfonylaminocarbonyl group having 2 to 31 carbon atoms which may have a substituent, a phenyl group which may have a substituent, a naphthyl group which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, a benzoyl group which may have a substituent, a naphthoyl group which may have a substituent, an arylalkyl group having 7 to 48 carbon atoms which may have a substituent, an arylalkylcarbonyl group having 8 to 49 carbon atoms which may have a substituent, an arylalkylaminocarbonyl group having 8 to 49 carbon atoms which may have a substituent, and an arylalkylsulfonylaminocarbonyl group having 8 to 49 carbon atoms which may have a substituent, (iii) when R3 is a hydrogen atom, R1 and R2 may be the same or independently different from each other, R1 and R2 each represent any one selected from the group consisting of an aliphatic hydrocarbon group having 7 to 30 carbon atoms which may have a substituent, an alkylaminocarbonyl group having 2 to 31 carbon atoms which may have a substituent, an alkylsulfonylaminocarbonyl group having 2 to 31 carbon atoms which may have a substituent, a phenyl group which may have a substituent, a naphthyl group which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, a benzoyl group which may have a substituent, a naphthoyl group which may have a substituent, an arylalkyl group having 7 to 48 carbon atoms which may have a substituent, an arylalkylcarbonyl group having 8 to 49 carbon atoms which may have a substituent, an arylalkylaminocarbonyl group having 8 to 49 carbon atoms which may have a substituent, and an arylalkylsulfonylaminocarbonyl group having 8 to 49 carbon atoms which may have a substituent.

2. The color developer according to claim 1, wherein R1 or R2 in formula (1) is a hydrogen atom.

3. The color developer according to claim 2, wherein R1 in formula (1) is a hydrogen atom.

4. The color developer according to claim 3, wherein in formula (1), R2 is any one selected from the group consisting of an optionally substituted alkylcarbonyl group having 2 to 18 carbon atoms, an optionally substituted alkylaminocarbonyl group having 2 to 18 carbon atoms, an optionally substituted alkylsulfonylaminocarbonyl group having 2 to 18 carbon atoms, an optionally substituted phenylaminocarbonyl group, an optionally substituted phenylsulfonylaminocarbonyl group, an optionally substituted benzoyl group, and an optionally substituted naphthoyl group; and R3 is any one selected from the group consisting of an optionally substituted phenylaminocarbonyl group, an optionally substituted phenylsulfonylaminocarbonyl group, an optionally substituted arylalkylaminocarbonyl group having 8 to 24 carbon atoms, and an optionally substituted arylalkylsulfonylaminocarbonyl group having 8 to 24 carbon atoms.

5. The developer according to claim 3, wherein in formula (1), R2 is any one selected from the group consisting of an alkylcarbonyl group having 6 to 18 carbon atoms which may have a substituent, an alkylaminocarbonyl group having 6 to 18 carbon atoms which may have a substituent, a phenylaminocarbonyl group which may have a substituent, a phenylsulfonylaminocarbonyl group which may have a substituent, a benzoyl group which may have a substituent, and a naphthoyl group which may have a substituent, and R3 is a phenylaminocarbonyl group which may have a substituent or a phenylsulfonylaminocarbonyl group which may have a substituent.

6. The color developer according to claim 1, wherein the compound represented by formula (1) is at least one of a compound represented by the following formula (1-1) and a compound represented by the following formula (1-2): (In formula (1-1), R1 to R3 have the same meanings as R1 to R3 in formula (1), respectively.) (In formula (1-2), R1 to R3 have the same meanings as R1 to R3 in formula (1), respectively.) 7. A heat-sensitive recording material having a support and a heat-sensitive recording layer provided on the support, wherein the heat-sensitive recording layer contains the color developer according to any one of claims 1 to 6.

8. The heat-sensitive recording material according to claim 7, wherein the heat-sensitive recording layer contains a leuco dye.

9. The heat-sensitive recording material according to claim 7, wherein the heat-sensitive recording layer contains a sensitizer.

10. The thermosensitive recording material according to claim 7, wherein the thermosensitive recording layer contains a stabilizer.

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