Heat-sensitive recording material containing non-phenolic color developer

Abstract

The present invention provides a thermosensitive recording material, a recording sheet formed from the thermosensitive recording material, and a method of forming an image using the thermosensitive recording material. An exemplary thermosensitive recording material includes a color-forming compound, a first non-phenolic color developer, and a second non-phenolic color developer.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application Serial No. 62 / 894,041, filed on August 30, 2019, the disclosure of which is incorporated by reference.

[0003] background

[0004] Embodiments described herein relate to a thermosensitive recording material including a combination of a first non-phenolic developer and a second non-phenolic developer, a recording sheet formed from such a thermosensitive recording material, and a method of forming an image using such a thermosensitive recording material.

[0005] So-called thermal papers are used for thermal printing of point-of-sale receipts. Such thermal papers form colored images by heating. Thermal papers usually consist of three main components: a color former; a sensitizer; and a developer. During the development process, the colorless color former is converted into a black chromophore, which is stabilized by the developer by complex formation. The widely used developer bisphenol A is cheap and technically satisfactory, but is suspected of having endocrine disrupting activity in both humans and the environment and may be classified as a "reproductive toxicant" in some jurisdictions. For example, from January 2020, the use of bisphenol A will be restricted in thermal papers for the European market. Another phenolic developer, bisphenol S, is also under environmental safety investigation.

[0006] Among the non-phenolic developers for commercial use, sulfonylurea derivatives such as N-p-tolylsulfonyl-N′-3-(p-toluenesulfonyloxy)phenylurea or urea derivatives such as described in EP 0526072 or WO 00 / 35679 can provide alternatives to the widely used phenolic products. However, although it is technically feasible to replace phenolic developers, the synthesis of such urea derivatives requires the use of special and semi-special raw materials. Therefore, it is not ideal to widely use urea derivatives in point-of-sale and / or economy grade thermal papers in terms of cost-effectiveness.

[0007] JP 2016-083858 A1 describes a further alternative for thermosensitive recording materials comprising a developer prepared in a three-step procedure.

[0008] It would therefore be desirable to provide a non-phenolic developer for thermosensitive recording materials which is a technically suitable and cost-effective alternative to the currently available phenolic and non-phenolic developers.

[0009] Overview

[0010] Provided are a thermosensitive recording material, a recording sheet formed from the thermosensitive recording material, and a method of forming an image using the thermosensitive recording material. An exemplary thermosensitive recording material includes a color-forming compound, a first non-phenolic color developer, and a second non-phenolic color developer.

[0011] An exemplary recording sheet includes a support and a recording composition layer on the support, wherein the recording composition is formed of a color-forming compound, a first non-phenolic color developer, and a second non-phenolic color developer.

[0012] An exemplary method of forming an image includes providing a heat-sensitive recording material of a color-forming compound, a first non-phenolic developer, and a second non-phenolic developer.

[0013] In an exemplary embodiment, the first non-phenolic developer has formula (I)

[0014]

[0015] wherein R and R1 are each independently hydrogen; C1-C 18 -alkyl; C1-C8-alkoxy-C1-C8-alkyl; (R9)2N-C1-C8-alkyl, wherein R9 represents C1-C8-alkyl or C5-C6-cycloalkyl; or a radical of formula (II)

[0016]

[0017] wherein R2, R3, R4, R5, R6 are each independently hydrogen; C1-C8-alkyl; -NH-C(=O)-R7 or -C(=O)-NH-R7, wherein R7 represents C1-C8-alkyl; -C(=O)OR8, wherein R8 represents C1-C8-alkyl; halogen (such as fluorine, chlorine, bromine or chlorine); or wherein R2 and R3, or R4 and R5 or both, or wherein R3 and R4, or R5 and R6 or both, or wherein (R2 and R3) and (R5 and R6), together represent a divalent hydrocarbon group having three or four carbon atoms (such as trimethylene, tetramethylene, 1,3-propenylene, 1,4-but-2-enylene or 1,3-butadienylene), wherein Q represents a single bond (single bond); bond) or C1-C8-alkylene, which may be branched or unbranched, and wherein, when the C1-C8-alkylene comprises more than two carbon atoms, the C1-C8-alkylene comprises a main chain containing one or more oxygen atoms between two carbon atoms.

[0018] In an exemplary embodiment, when R8 represents halogen, the halogen is chlorine. Exemplary embodiments of Q include -CH2-, -CH2-CH2-, -CH2-O-, -CH2-CH2-O-, -CH2-CH2-CH2-, -CH2-CH2-CH2-CH2-, -C(Me)H-, -C(Et)H-, -C(n-Pr)H-, -C(i-Pr)H-, -C(n-Bu)H-, -C(i-Bu)H-, -C(sec-Bu)H-, -C(tert-Bu)H-, -C(Me)HCH2-, -CMe2CH2-, or in a specific embodiment, include -CH2-, -CH2-CH2-, -CH2-CH2-O- and -C(Me)H-.

[0019] In certain embodiments, the second non-phenolic developer is a compound selected from the group consisting of:

[0020] (i) A compound represented by the following formula (NI):

[0021]

[0022] wherein R1, R2 and R3 each independently represent a hydrogen atom, a halogen atom, a nitro group, a C1-C6 alkyl group, a C1-C6 alkoxy group, a C2-C6 alkenyl group, a C1-C6 fluoroalkyl group, an N(R4)2 group, an NHCOR5, an optionally substituted phenyl group or an optionally substituted benzyl group;

[0023] wherein R4 represents a hydrogen atom, a phenyl group, a benzyl group or a C1-C6 alkyl group;

[0024] Wherein R5 represents a C1-C6 alkyl group;

[0025] wherein n1 and n3 each independently represent any integer from 1 to 5; and

[0026] wherein n2 represents any integer from 1 to 4; and

[0027] (ii) A compound represented by the following formula (N-II):

[0028]

[0029] wherein R1, R2 and R3 each independently represent a hydrogen atom, a halogen atom, a nitro group, a C1-C6 alkyl group, a C1-C6 alkoxy group, a C2-C6 alkenyl group, a C1-C6 fluoroalkyl group, an N(R4)2 group, an NHCOR5, an optionally substituted phenyl group or an optionally substituted benzyl group;

[0030] Where n2 represents any integer from 1 to 4;

[0031] wherein n3 represents any integer from 1 to 5; and

[0032] wherein n4 represents any integer from 1 to 7; and

[0033] (iii) a compound represented by the following formula (N-III):

[0034]

[0035] wherein R1, R2 and R3 each independently represent a hydrogen atom, a halogen atom, a nitro group, a C1-C6 alkyl group, a C1-C6 alkoxy group, a C2-C6 alkenyl group, a C1-C6 fluoroalkyl group, an N(R4)2 group, an NHCOR5, an optionally substituted phenyl group or an optionally substituted benzyl group;

[0036] Where n2 represents any integer from 1 to 4;

[0037] wherein n3 represents any integer from 1 to 5; and

[0038] Where n4 represents any integer from 1 to 7.

[0039] In other embodiments, the second non-phenolic developer is a compound of formula (PI)

[0040]

[0041] Wherein R1 is unsubstituted or substituted phenyl or naphthyl,

[0042] wherein R3 and R4 are independently hydrogen, C1-C8 alkyl, halogen-substituted C1-C8 alkyl, C1-C8 alkoxy-substituted C1-C8 alkyl, C1-C8 alkoxy, halogen-substituted C1-C8 alkoxy, C1-C8 alkylsulfonyl, halogen, phenyl, phenoxy or phenoxycarbonyl,

[0043] Wherein X is a group of the formula

[0044]

[0045] wherein B is a linking group of the formula -O-SO2-, -SO2-O-, -SO2_NH- or -CO-NH-SO2-, and

[0046] wherein R2 is phenyl, which is unsubstituted or substituted by C1-C8 alkyl, halogen-substituted C1-C8 alkyl, C1-C8 alkoxy-substituted C1-C8 alkyl, C1-C8 alkoxy, halogen-substituted C1-C8 alkoxy or halogen; or R2 is naphthyl or benzyl, which is substituted by C1-C4 alkyl or halogen, provided that if B is not a linking group of the formula -O-SO2-, then R2 is unsubstituted or substituted phenyl or naphthyl.

[0047] In other embodiments, the second non-phenolic developer is a compound of formula (QI)

[0048]

[0049] wherein R1 is phenyl or naphthyl, which is unsubstituted or substituted by C1-C8 alkyl, C1-C8 alkoxy or halogen, or R1 is C1-C 20 Alkyl, which may be unsubstituted or substituted by C1-C8-alkoxy or halogen;

[0050] Wherein X is a group of the formula

[0051]

[0052] Wherein A is unsubstituted or substituted phenylene, naphthylene or C1-C 12 Alkylene, or an unsubstituted or substituted heterocyclic group;

[0053] wherein B is a linking group of the formula -O-SO2-, -SO2-O-, -NH-SO2-, -SO2-NH-, -S-SO2-, -O-CO-NH-, -NH-CO-, -NH-CO-O-, -S-CO-NH-, -S-CS-NH-, -CO-NH-SO2-, -O-CO-NH-SO2-, -NH=CH-, -CO-NH-CO-, -S-, -CO-, -O-, -SO2-NH-CO-, -O-CO-O- or -O-PO-(OR2)2; and

[0054] wherein R2 is aryl, which is unsubstituted or substituted by C1-C8 alkyl, halogen-substituted C1-C8 alkyl, C1-C8 alkoxy-substituted C1-C8 alkyl, C1-C8 alkoxy, halogen-substituted C1-C8 alkoxy or halogen; or R2 is benzyl, which is unsubstituted or substituted by C1-C8 alkyl, halogen-substituted C1-C8 alkyl, C1-C8 alkoxy-substituted C1-C8 alkyl, C1-C8 alkoxy, halogen-substituted C1-C8 alkoxy or halogen; or R2 is C1-C 20 Alkyl, which is unsubstituted or substituted by C1-C8 alkoxy, halogen, phenyl or naphthyl,

[0055] Provided that if B is not a linking group of the formula -O-SO2-, then R2 is unsubstituted or substituted phenyl, naphthyl or C1-C8 alkyl, and if B is -O-, then R2 is not alkyl, and further provided that if B represents -O-SO2- or -SO2-O-, then R2 is not C1-C8 20 alkyl.

[0056] As described herein, when used in combination with a second non-phenolic developer, the dynamic sensitivity of the first non-phenolic developer is improved. In addition, as described herein, when used in combination with a second non-phenolic developer, the maximum optical density image of the first non-phenolic developer is improved. In addition, as described herein, when used in combination with a second non-phenolic developer, the recorded image stability of the first non-phenolic developer is improved. The improvement in plasticizer migration from the top side or back side of the heat-sensitive medium is significant.

[0057] In addition, in the case of 1-[2-(benzenesulfonylamino)-phenyl]-3-phenylurea, when used in combination with the first non-phenolic developer, the recorded image stability of the second non-phenolic developer is improved. The improvements in water resistance, oil resistance, and plasticizer migration from the top side or back side of the heat-sensitive medium are significant. Almost all preservations are improved by this combination.

[0058] In the case of 4-methylphenylsulfonic acid [3-(p-toluenesulfonylcarbamoylamino)phenyl ester], the recorded image stability of the second non-phenol type developer is improved in terms of water resistance and heat resistance as well as light resistance.

[0059] This Summary is provided to introduce a selection of concepts in a simplified form that are further described in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0060] Details

[0061] The following detailed description is merely illustrative in nature and is not intended to limit the embodiments of the subject matter or the application and use of these embodiments. As used herein, the wording "exemplary" means "serving as an example, instance or illustration". Any exemplary embodiment described herein is not necessarily to be construed as being preferred or advantageous over other embodiments. Furthermore, no intention is to be bound by any expressed or implied theory given in the above technical field, background, summary or the following detailed description.

[0062] As described herein, exemplary thermosensitive recording materials include a non-phenolic developer combination, the non-phenolic developer combination including a first non-phenolic developer and a second non-phenolic developer. In certain embodiments, the non-phenolic developer combination consists essentially of a first non-phenolic developer and a second non-phenolic developer. In other embodiments, the non-phenolic developer combination consists of a first non-phenolic developer and a second non-phenolic developer. In other embodiments, the non-phenolic developer combination includes a first non-phenolic developer, a second non-phenolic developer, and additional (one or more) non-phenolic developers.

[0063] Furthermore, the exemplary heat-sensitive recording material may include a sensitizer or may not include a sensitizer. In an exemplary embodiment, the heat-sensitive recording material includes benzyl 2-naphthyl ether (CAS No. 613-62-7) as a sensitizer.

[0064] In an exemplary embodiment, the first non-phenolic developer is 5-(N-3-methylphenyl-sulfonylamino)-(N′, N′-bis-(3-methylphenyl)-isophthalic acid diamide, also referred to herein as Pergafast-425 or PF-425. In an exemplary embodiment, the second non-phenolic developer is 1-[2-(benzenesulfonylamino)-phenyl]-3-phenylurea (CAS No. 215917-77-4), also known as NKK-1304. In other exemplary embodiments, the second non-phenolic developer is 4-methylbenzenesulfonic acid [3-(p-toluenesulfonylaminoformylamino)phenyl ester] (CAS No. 232938-43-1), also known as Pergafast-201 or PF-201.

[0065] As described herein, when used in combination with a second non-phenolic developer, the dynamic sensitivity of the first non-phenolic developer is improved. In addition, as described herein, when used in combination with a second non-phenolic developer, the maximum optical density image of the first non-phenolic developer is improved. In addition, as described herein, when used in combination with a second non-phenolic developer, the recorded image stability of the first non-phenolic developer is improved. The improvement in plasticizer migration from the top side or back side of the heat-sensitive medium is significant.

[0066] In addition, in the case of 1-[2-(benzenesulfonylamino)-phenyl]-3-phenylurea, when used in combination with the first non-phenolic developer, the recorded image stability of the second non-phenolic developer is improved. The improvements in water resistance, oil resistance, and plasticizer migration from the top or back side of the heat-sensitive medium are significant. Almost all protection is improved by this combination.

[0067] In the case of 4-methylbenzenesulfonic acid [3-(p-toluenesulfonylcarbamoylamino)phenyl ester], the recorded image stability of the second non-phenol type developer is improved in terms of water resistance and heat resistance and light resistance.

[0068] In certain embodiments, the ratio of the first non-phenolic developer to the second non-phenolic developer is 10:90 to 90:10. For example, the lower limit of the ratio of the second non-phenolic developer to the second non-phenolic developer is 10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40:60, 45:55, 50:50, 55:45, 60:40, 65:35, 70:30, 75:25, 80:20 or 85:15. Further, the upper limit of the ratio of the first non-phenolic developer to the second non-phenolic developer is 90:10, 85:15, 80:20, 75:25, 70:30, 65:35, 60:40, 55:45, 50:50, 45:55, 40:60, 35:65, 30:70, 25:75, 20:80 or 15:85. All ratios are provided as a dry proportion of the mixture of the two developers.

[0069] The first non-phenolic color developer

[0070] In an exemplary embodiment, the first non-phenolic developer has formula (I):

[0071]

[0072] wherein R and R1 are each independently hydrogen; C1-C 18 -alkyl; C1-C8-alkoxy-C1-C8-alkyl; (R9)2N-C1-C8-alkyl, wherein R9 represents C1-C8-alkyl or C5-C6-cycloalkyl; or a radical of formula (II)

[0073]

[0074] wherein R2, R3, R4, R5, R6 are each independently hydrogen; C1-C8-alkyl; -NH-C(=O)-R7 or -C(=O)-NH-R7, wherein R7 represents C1-C8-alkyl; -C(=O)OR8, wherein R8 represents C1-C8-alkyl; halogen (such as fluorine, chlorine, bromine or chlorine); or wherein R2 and R3, or R4 and R5 or both, or wherein R3 and R4, or R5 and R6 or both, or wherein (R2 and R3) and (R5 and R6), together representing a divalent hydrocarbon group having three or four carbon atoms (such as trimethylene, tetramethylene, 1,3-propenylene, 1,4-but-2-enylene or 1,3-butadienylene), wherein Q represents a direct bond or a C1-C8-alkylene group which may be branched or unbranched and wherein, when the C1-C8-alkylene group comprises more than two carbon atoms, the C1-C8-alkylene group comprises a main chain containing one or more oxygen atoms between two carbon atoms.

[0075] In an exemplary embodiment, when R8 represents halogen, the halogen is chlorine.

[0076] Exemplary embodiments of Q include -CH2-, -CH2-CH2-, -CH2-O-, -CH2-CH2-O-, -CH2-CH2-CH2-, -CH2-CH2-CH2-CH2-, -C(Me)H-, -C(Et)H-, -C(n-Pr)H-, -C(i-Pr)H-, -C(n-Bu)H-, -C(i-Bu)H-, -C(sec-Bu)H-, -C(tert-Bu)H-, -C(Me)HCH2-, -CMe2CH2-, or in specific embodiments, include -CH2-, -CH2-CH2-, -CH2-CH2-O-, and -C(Me)H-.

[0077] In an exemplary embodiment, C1-C 18 -alkyl represents methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, tert-pentyl (1,1-dimethylpropyl), 1,1,3,3-tetramethylbutyl, n-hexyl, 2-methylpentyl, neopentyl, n-heptyl, 2-ethyl-hexyl or n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl or n-octadecyl.

[0078] In an exemplary embodiment, C1-C8-alkyl is methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, tert-pentyl (1,1-dimethylpropyl), 1,1,3,3-tetramethylbutyl, n-hexyl, 2-methylpentyl, neopentyl, n-heptyl, 2-ethyl-hexyl or n-octyl or tridecyl. In a specific embodiment, C1-C8-alkyl is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, 2-ethyl-hexyl or tridecyl.

[0079] In an exemplary embodiment, C1-C8-alkoxy represents methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, n-pentoxy, n-hexoxy, n-heptyloxy or n-octyloxy. In a specific embodiment, C1-C8-alkoxy represents C1-C6-alkoxy, such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy or n-hexyloxy.

[0080] In an exemplary embodiment, C1-C8-alkoxy-C1-C8-alkyl represents methoxymethyl, ethoxymethyl, n-propoxymethyl, isopropoxymethyl, n-butoxymethyl, n-pentoxymethyl, n-hexoxymethyl, n-heptyloxymethyl, n-octyloxymethyl, methoxyethyl, ethoxyethyl, n-propoxyethyl, isopropoxyethyl, n-butoxyethyl, n-pentyloxyethyl, n-hexyloxyethyl, n-heptyloxyethyl, n-octyloxyethyl, methoxymethyl, 1-methoxyethyl, 2-methoxyethyl, 3-methoxy-n-propyl, 1-methoxy-2-propyl, 4-methoxy-n-butyl, 5-methoxy-n-pentyl, 6-methoxy-n-hexyl, 7-methoxy-n-heptyl, 8-methoxy or n-octyl. In a specific embodiment, C1-C8-alkoxy-C1-C8-alkyl represents 2-methoxyethyl.

[0081] In an exemplary embodiment, C5-C6-cycloalkyl represents cyclopentyl or cyclohexyl. In a specific embodiment, C5-C6-cycloalkyl represents cyclohexyl.

[0082] In exemplary embodiments, (R9)2N-C1-C8-alkyl is 2-(dimethylamino)-methyl, 2-(dimethylamino)-ethyl, 2-(diethylamino)-ethyl, 2-(diisopropylamino)-ethyl, 2-(n-propylamino)-ethyl, 3-(dimethylamino)-propyl or 3-(cyclohexylamino)-propyl.

[0083] In certain embodiments, wherein R2 and R3, or R4 and R5 or both, or wherein R3 and R4, or R5 and R6 or both, or wherein (R2 and R3) and (R5 and R6), together represent a divalent hydrocarbon group having three or four carbon atoms (such as trimethylene, tetramethylene, 1,3-propenylene, 1,4-but-2-enylene or 1,3-butadienylene), R2 and R3 together represent tetramethylene or R2 and R3 together represent tetramethylene.

[0084] In exemplary embodiments, the group of formula (II) is phenyl, benzyl, 3-methylphenyl, 2,6-diethylphenyl, o-isopropylphenyl, p-acetamidophenyl, 1-phenylethyl, 2-phenylethyl, 2-phenoxyethyl, 1-tetrahydronaphthyl or 2-tetrahydronaphthyl.

[0085] In certain exemplary embodiments, the first non-phenolic developer has formula (Ia):

[0086]

[0087] or the first non-phenolic developer has formula (Ib)

[0088]

[0089] Exemplary first non-phenolic color developers of formula (Ia) include 5-(N-benzyl-sulfonylamino)-(N′, N″-dibenzyl)-isophthalic acid-diamide, 5-(N-3-methylphenyl-sulfonylamino)-(N′, N″-bis-(3-methylphenyl)-isophthalic acid-diamide, 5-(N-2,6-di-ethylphenyl-sulfonylamino)-(N′, N″-bis-(2,6-diethylphenyl)-isophthalic acid-diamide, 5-(N-phenyl-sulfonylamino)-(N′, N″-bis-(o-isopropylphenyl)-isophthalic acid-diamide, 5-(N-isopropyl-phenyl-sulfonylamino)-(N′, N″-bis-(o-isopropylphenyl)-isophthalic acid-diamide, 5-(N-2,6-di-ethylphenyl-sulfonylamino)-(N′, N″-bis-(2,6-diethylphenyl)-isophthalic acid-diamide, 5-(N-phenyl-sulfonylamino)-(N′, N″-bis-(o-isopropylphenyl)-isophthalic acid-diamide, 5-(N- isophthalic acid diamide, 5-(N-1-tetrahydronaphthyl-sulfonylamino)-(N′, N″-bis-(1-tetrahydronaphthyl)-isophthalic acid diamide, 5-(N-3-methylphenyl-sulfonylamino)-(N′, N″-bis-(3-methylphenyl)-isophthalic acid diamide, 5-(N-1-phenylethyl-sulfonylamino)-(N′, N″-bis-(1-phenylethyl)-isophthalic acid diamide, 5-(N-2-phenylethyl-sulfonylamino)-(N′, N″-bis-(2-phenylethyl)-isophthalic acid diamide, 5-(N-2,6-diethylphenyl-sulfonylamino)-(N′, N″-bis-(2-phenylethyl)-isophthalic acid diamide, isophthalic acid diamide, 5-(N-butyl-sulfonylamino)-(N′, N″-di-n-butyl-isophthalic acid diamide, 5-(N-2-ethylhexyl-sulfonylamino)-(N′, N″-di-2-ethylhexylisophthalic acid diamide, 5-(N-benzyl-sulfonylamino)-(N′, N″-diphenyl)-isophthalic acid diamide, 5-(N-phenyl-sulfonylamino)-(N′, N″-dibenzyl)-isophthalic acid diamide, 5-(N-benzylsulfonylamino)-(N′, N″-bis-(3-methyl-phenyl)-isophthalic acid diamide, 5-(N-butyl-sulfonylamino)-(N′, N″-di-n-butyl-isophthalic acid diamide -(N′, N″-bis-(3-methyl-phenyl)-isophthalic acid-diamide, 5-(N-1-phenyl-ethyl-sulfonylamino)-(N′, N″-bis-(3-methyl-phenyl)-isophthalic acid-diamide, 5-(N-2-phenyl-ethyl-sulfonylamino)-(N′, N″-bis-(3-methyl-phenyl)-isophthalic acid-diamide, 5-(N-2-methoxy-ethyl-sulfonylamino)-(N′, N″-bis-(3-methyl-phenyl)-isophthalic acid-diamide, 5-(N-n-octyl-sulfonylamino)-(N′, N″-bis-(3-methyl-phenyl)-isophthalic acid-diamide, 5-(N-benzyl-sulfonylamino)-(N′, N″-bis-(2,6-diethyl-phenyl)-isophthalic acid-diamide, 5-(N-octyl-sulfonylamino)-(N′,N″-bis-(2,6-diethyl-phenyl)-isophthalic acid-diamide and 5-(N-2-phenoxy-ethyl-sulfonylamino)-(N′,N″-bis-(2,6-diethyl-phenyl)-isophthalic acid-diamide.

[0090] In certain exemplary embodiments, the heat-sensitive recording material further comprises a diamide, such as a diamide of formula (Ic)

[0091]

[0092] In a specific exemplary embodiment, the first non-phenolic developer has formula (Ia), and the thermosensitive recording material includes a diamide of formula (Ic), and the amount of diamide (Ic) is about 0.01 to about 10 mol% relative to the first non-phenolic developer (Ia).

[0093] Another embodiment described herein relates to polymorphic modifications, particularly 5-(N-3-methylphenyl-sulfonylamino)-(N′, N″-bis-(3-methylphenyl)-isophthalic acid diamide, three different polymorphic modifications of which were found: an α-form having a melting point of 211.2°C (measured using differential scanning calorimetry, i.e., DSC), a β-form having a melting point of 192.2°C (measured by DSC), and a γ-form having a melting point of 215.6°C (measured by DSC).

[0094] The second non-phenolic color developer

[0095] In an exemplary embodiment, the second non-phenolic developer is:

[0096] A compound represented by the following formula (I):

[0097]

[0098] (wherein R1 to R3 represent a hydrogen atom, a halogen atom, a nitro group, a C1-C6 alkyl group, a C1-C6 alkoxy group, a C2-C6 alkenyl group, a C1-C6 fluoroalkyl group, an N(R4)2 group (wherein R4 represents a hydrogen atom, a phenyl group, a benzyl group or a C1-C6 alkyl group), NHCOR5 (wherein R5 represents a C1-C6 alkyl group), an optionally substituted phenyl group or an optionally substituted benzyl group; n1 and n3 each independently represent any integer from 1 to 5; and n2 represents any integer from 1 to 4);

[0099] A compound represented by the following formula (II):

[0100]

[0101] (wherein R1 to R3 represent the same as R1 to R3 defined in formula (I); n2 and n3 represent the same as n2 and n3 defined in formula (I); and n4 represents any integer from 1 to 7); and

[0102] A compound represented by the following formula (III):

[0103]

[0104] (wherein R1 to R3 represent the same as R1 to R3 defined in formula (I); and n2, n3 and n4 represent the same as n2, n3 and n4 defined in formula (I) and formula (II).

[0105] In certain exemplary embodiments, Formula (I) is the following Formula (IV):

[0106]

[0107] (wherein R1 and R3 represent the same as R1 and R3 defined in formula (I).

[0108] In certain exemplary embodiments, Formula (I) is the following Formula (V):

[0109]

[0110] (wherein R1 represents the same as R1 defined in formula (I)).

[0111] In an exemplary embodiment, the second non-phenolic developer is a benzenesulfonamide compound.

[0112] In formulae (I), (II) and (III), examples of R1 to R3 are selected from:

[0113] Hydrogen atoms;

[0114] a halogen atom, such as a fluorine atom, a chlorine atom, a bromine atom or an iodine atom;

[0115] Nitro;

[0116] linear, branched or cyclic C1-C6 alkyl, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, hexyl, isohexyl, cyclopropyl, cyclobutyl, 2-methylcyclopropyl, cyclopropylmethyl, cyclopentyl or cyclohexyl;

[0117] linear, branched or cyclic C1-C6 alkoxy, such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, pentyloxy, isopentyloxy, hexyloxy, cyclopropyloxy, cyclobutyloxy, 2-methylcyclopropyloxy, cyclopropylmethoxy, cyclopentyloxy or cyclohexyloxy;

[0118] C2-C6 alkenyl, such as vinyl, allyl, isopropenyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1,3-butenyl or 2-methyl-2-propenyl;

[0119] C1-C6 fluoroalkyl, such as trifluoromethyl, perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluorohexyl or perfluorocyclohexyl;

[0120] N(R4)2 group (wherein R4 represents a hydrogen atom, a phenyl group, a benzyl group or a C1-C6 alkyl group);

[0121] ·NHCOR5 (wherein R5 represents a C1-C6 alkyl group);

[0122] Optionally substituted phenyl; and

[0123] - Optionally substituted benzyl.

[0124] In an exemplary embodiment, for the second non-phenolic developer, R1 to R3 each represent a hydrogen atom or a linear C1-C6 alkyl group. In particular, R1 may represent a hydrogen atom or a methyl group, and R2 and R3 may each represent a hydrogen atom.

[0125] Examples of the C1-C6 alkyl group of the above-mentioned R4 or R5 used as the second non-phenolic developer include the same specific examples of the C1-C6 alkyl group of the above-mentioned R1 used as the second non-phenolic developer.

[0126] Examples of substituents used to "optionally substituted" a group include:

[0127] Hydroxyl;

[0128] a halogen atom, such as a fluorine atom, a chlorine atom, a bromine atom or an iodine atom;

[0129] C1-C6 alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, n-hexyl, isohexyl, 1-methylpentyl or 2-methylpentyl; and

[0130] C1-C6 alkoxy, such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy or tert-butoxy.

[0131] In an exemplary embodiment, the second non-phenolic developer is a benzenesulfonamide compound selected from the group consisting of

[0132] A compound represented by the following formula (I):

[0133]

[0134] (wherein R1 to R3 and n1 to n3 represent the same as R1 to R3 and n1 to n3 defined above, with the proviso that the following cases are excluded: R2 and R3 each represent a hydrogen atom, and R1 represents any one of a hydrogen atom, a p-methyl group, a m-methyl group and a p-chloro group),

[0135] A compound represented by the following formula (II):

[0136]

[0137] (wherein R1 to R3 represent the same as R1 to R3 defined above, n2 and n3 represent the same as n2 and n3 defined above, and n4 represents any integer from 1 to 7), and

[0138] A compound represented by the following formula (III):

[0139]

[0140] (wherein R1 to R3 represent the same as R1 to R3 defined above, and n2, n3 and n4 represent the same as n2, n3 and n4 defined above).

[0141] Representative examples of the compounds represented by formulae (I) to (III) of the second non-phenolic developer include 4-methyl-N-(2-(3-phenylureido)phenyl)benzenesulfonamide and N-(2-(3-phenylureido)phenyl)benzenesulfonamide.

[0142] In one exemplary embodiment, the thermosensitive coloring layer of the thermosensitive recording medium includes a developer having the following formula:

[0143]

[0144] This corresponds to the general formula (I) above, wherein R1, R2 and R3 are all hydrogen atoms.

[0145] The second non-phenolic color developer

[0146] In one exemplary embodiment, the second non-phenolic developer is a compound of the formula

[0147]

[0148] Wherein R1 is unsubstituted or substituted phenyl, naphthyl or C1-C 20 alkyl,

[0149] Wherein X is a group of the formula

[0150]

[0151] Wherein A is unsubstituted or substituted phenylene, naphthylene or C1-C 12 an alkylene group, or an unsubstituted or substituted heterocyclic group,

[0152] wherein B is a linking group of the formula -O-SO2-, -SO2-O-, -NH-SO2-, -SO2-NH-, -S-SO2-, -O-CO-, -O-CO-NH-, -NH-CO-, -NH-CO-O-, -S-CO-NH-, -S-CS-NH-, -CO-NH-SO2-, -O-CO-NH-SO2-, -NH=CH-, -CO-NH-CO-, -S-, -CO-, -O-, -SO2-NH-CO-, -O-CO-O- and -O-PO-(OR2)2, and

[0153] Wherein R2 is unsubstituted or substituted aryl or benzyl or C1-C 20 alkyl,

[0154] Provided that, if B is not a linking group of the formula -O-SO2-, then R2 is unsubstituted or substituted phenyl, naphthyl or C1-C8 alkyl, and if B is -O-, then R2 is not alkyl.

[0155] In an exemplary embodiment, R1 as phenyl or naphthyl may be unsubstituted or substituted, for example, by C1-C8 alkyl, C1-C8 alkoxy or halogen. Exemplary substituents are C1-C4 alkyl, especially methyl or ethyl; C1-C4 alkoxy, especially methoxy or ethoxy; or halogen, especially chlorine. In an exemplary embodiment, R1 as naphthyl is unsubstituted. In an exemplary embodiment, R1 as phenyl is substituted, especially by one of the above-mentioned alkyl substituents.

[0156] As C1-C 20 The R1 of the alkyl group may be unsubstituted or substituted, for example, by C1-C8 alkoxy or halogen. Exemplary substituents are C1-C4 alkoxy, especially methoxy or ethoxy; or halogen, especially chlorine. In an exemplary embodiment, as C1-C 20 The alkyl group R1 is unsubstituted.

[0157] In an exemplary embodiment, R1 is phenyl which is unsubstituted or substituted by C1-C8 alkyl, C1-C8 alkoxy or halogen. Most importantly, it is substituted phenyl. In an exemplary embodiment, the phenyl is substituted by C1-C4 alkyl, such as methyl.

[0158] In an exemplary embodiment, X is a group of the formula

[0159]

[0160] In particular, the group of the formula

[0161]

[0162] A as phenylene or naphthylene may be unsubstituted or substituted by, for example, C1-C8 alkyl, halogen-substituted C1-C8 alkyl, C1-C8 alkoxy-substituted C1-C8 alkyl, C1-C8 alkoxy, halogen-substituted C1-C8 alkoxy, C1-C8 alkylsulfonyl, halogen, phenyl, phenoxy or phenoxycarbonyl. Preferred alkyl and alkoxy substituents are those containing 1 to 4 carbon atoms. Preferred substituents are C1-C8 alkyl, halogen-substituted C1-C8 alkyl, C1-C8 alkyl-sulfonyl or halogen. A as naphthylene is preferably unsubstituted.

[0163] A as a heterocyclic group is preferably pyrimidinyl which is unsubstituted or substituted by C1-C8 alkyl, especially C1-C4 alkyl.

[0164] As C1-C 12 A of the alkylene group is preferably C1-C8 alkylene, especially C1-C4 alkylene.

[0165] Preferred radicals A are phenylene which is unsubstituted or substituted by C1-C8 alkyl, halogen-substituted C1-C8 alkyl, C1-C8 alkoxy-substituted C1-C8 alkyl, C1-C8 alkoxy, halogen-substituted C1-C8 alkoxy, C1-C8 alkylsulfonyl, halogen, phenyl, phenoxy or phenoxycarbonyl (especially C1-C8 alkyl, halogen-substituted C1-C8 alkyl, C1-C8 alkylsulfonyl or halogen).

[0166] Highly preferred radical A is phenylene which is unsubstituted or substituted by C1-C4-alkyl or halogen, especially unsubstituted phenylene.

[0167] Preferred linking groups B are those of the formula -O-SO2-, -SO2-O-, -SO2-NH-, -S-SO2-, -O-, -O-CO- and -O-CO-NH-, especially the linking groups of the formula -O-SO2-, -SO2-O- and -SO2-NH-. Highly preferred are the linking groups B of the formula -O-SO2- and -O-.

[0168] R2 as aryl is preferably phenyl or naphthyl, which may be unsubstituted or substituted by, for example, C1-C8 alkyl, halogen-substituted C1-C8 alkyl, C1-C8 alkoxy-substituted C1-C8 alkyl, C1-C8 alkoxy, halogen-substituted C1-C8 alkoxy or halogen. Preferred alkyl and alkoxy substituents are those containing 1 to 4 carbon atoms. Preferred substituents are C1-C4 alkyl and halogen. R2 as naphthyl is preferably unsubstituted.

[0169] R2 as a benzyl group may be substituted with the substituents given for R2 as a phenyl group or a naphthyl group. An unsubstituted benzyl group is preferred.

[0170] As C1-C 20 R2 of alkyl is preferably C1-C8 alkyl, especially C1-C6 alkyl, and may be unsubstituted or substituted by, for example, C1-C8 alkoxy, halogen, phenyl or naphthyl. Unsubstituted alkyl is preferred, especially C1-C4 alkyl.

[0171] Preferred radicals R2 are C1-C6 alkyl; halogen-substituted C1-C6 alkyl; phenyl-substituted C1-C6 alkyl; naphthyl-substituted C1-C6 alkyl; phenyl, which is unsubstituted or substituted by C1-C8 alkyl, halogen-substituted C1-C8 alkyl, C1-C8 alkoxy-substituted C1-C8 alkyl, C1-C8 alkoxy, halogen-substituted C1-C8 alkoxy or halogen; naphthyl and benzyl substituted by C1-C4 alkyl or halogen.

[0172] Highly preferred radicals R2 are C1-C4-alkyl; halogen-substituted C1-C4-alkyl; phenyl which is unsubstituted or substituted by C1-C4-alkyl or halogen; naphthyl and benzyl which are unsubstituted or substituted by C1-C4-alkyl or halogen, especially phenyl which is unsubstituted or substituted by C1-C4-alkyl.

[0173] Preferred is a developer of formula (1), wherein

[0174] R1 is a phenyl group substituted by a C1-C4 alkyl group, preferably a methyl group,

[0175] X is a group of the formula

[0176]

[0177] A is unsubstituted or substituted phenylene with C1-C8 alkyl or halogen, preferably unsubstituted phenylene, such as 1,3-phenylene,

[0178] B is a linking group of the formula -O-SO2- or -O-, and

[0179] R2 is phenyl, naphthyl or benzyl which is unsubstituted or substituted by C1-C4 alkyl or halogen, especially phenyl which is substituted by C1-C4 alkyl.

[0180] In a particularly preferred embodiment, the thermosensitive coloring layer of the exemplary thermosensitive recording medium comprises a second developer having the following formula:

[0181]

[0182] This developer is sold under the trade name PERGAFAST 201 by the company SOLENIS.

[0183] Color forming compounds

[0184] Colour-forming compounds are, for example, triphenylmethanes, lactones, benzoxazines, spiropyrans or preferably fluorans.

[0185] Exemplary color formers include, but are not limited to, 3-diethylamino-6-methylfluoran, 3-dimethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-(2,4-dimethylanilino)fluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3-diethylamino-6-methyl-7-(3-trifluoromethylanilino)fluoran, 3-diethylamino-6-methyl-7-(2-chloroanilino)fluoran, 3-diethylamino-6-methyl-7-(4-chloroanilino)fluoran, 3-diethylamino-6-methyl-7-(2-fluoroanilino)fluoran, 3-diethylamino-6-methyl-7-(4-n-octylanilino)fluoran, ) fluoran, 3-diethylamino-7-(4-n-octylanilino) fluoran, 3-diethylamino-7-(n-octylamino) fluoran, 3-diethylamino-7-(dibenzylamino) fluoran, 3-diethylamino-6-methyl-7-(dibenzylamino) fluoran, 3-diethylamino-6-chloro-7-methylfluoran, 3-diethylamino-7-tert-butylfluoran, 3-diethylamino-7-carboxyethylfluoran, 3-diethylamino-6-chloro-7-anilino fluoran, 3-diethylamino-6-methyl-7-(3-methylanilino) fluoran, 3-diethylamino-6-methyl-7-(4-methylanilino) fluoran, 3-diethylamino-6-ethoxyethyl-7-anilino fluoran, 3-diethylamino- 7-methylfluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-7-(3-trifluoromethylanilino)fluoran, 3-diethylamino-7-(2-chloroanilino)fluoran, 3-diethylamino-7-(2-fluoroanilino)fluoran, 3-diethylamino-benzo[a]fluoran, 3-diethylamino-benzo[c]fluoran, 3-dibutylamino-7-dibenzylaminofluoran, 3-dibutylamino-7-anilinofluoran, 3-diethylamino-7-anilinofluoran, 3-dibutylamino-6-methylfluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-(2,4-dimethylanilino)fluoran, 3-dibutylamino-6-methyl-7- (2-chloroanilino)fluoran, 3-dibutylamino-6-methyl-7-(4-chloroanilino)fluoran, 3-dibutylamino-6-methyl-7-(2-fluoroanilino)fluoran, 3-dibutylamino-6-methyl-7-(3-trifluoromethylanilino)fluoran, 3-dibutylamino-6-ethoxyethyl-7-anilinofluoran, 3-dibutylamino-6-chloro-anilinofluoran, 3-dibutylamino-6-methyl-7-(4-methylanilino)fluoran, 3-dibutylamino-7-(2-chloroanilino)fluoran, 3-dibutylamino-7-(2-fluoroanilino)fluoran, 3-dibutylamino-7-(N-methyl-N-formylamino)fluoran, 3-dipentylamino-6-methyl-7-anilinofluoran,3-Dipentylamino-6-methyl-7-(4-2-chloroanilino)fluoran, 3-dipentylamino-7-(3-trifluoromethylanilino)fluoran, 3-dipentylamino-6-chloro-7-anilinofluoran, 3-dipentylamino-7-(4-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-p-toluidino)-6-methyl-7-anilinofluoran Fluoran, 3-(N-ethyl-N-isopentylamino)-6-methyl-7-anilinofluoran, 3-(N-ethyl-N-isopentylamino)-6-chloro-7-anilinofluoran, 3-(N-ethyl-N-tetrahydrofurfurylamino)-6-methyl-7-anilinofluoran, 3-(N-ethyl_N-isobutylamino)-6-methyl-7-anilinofluoran, 3-(N-butyl-N-isopentylamino)-6-methyl-7-anilinofluoran, 3-(N-isopropyl-N-3-pentylamino)-6-methyl-7-anilinofluoran, 3-(N-ethyl-N-ethoxypropylamino)-6-methyl-7-anilinofluoran, 3-cyclohexylamino-6-chlorofluoran, 2-methyl-6-p-(p-dimethylaminophenyl)- 2-(p-dimethylaminophenyl)aminoanilinofluoran, 2-methoxy-6-p-(p-dimethylaminophenyl)aminoanilinofluoran, 2-chloro-3-methyl-6-p-(p-phenylaminophenyl)aminoanilinofluoran, 2-diethylamino-6-p-(p-dimethylaminophenyl)aminoanilinofluoran, 2-phenyl-6-methyl-6-p-(p-phenylaminophenyl)aminoanilinofluoran, 2-benzyl-6-p-(p-phenylaminophenyl)aminoanilinofluoran, 3-methyl-6-p-(p-dimethylaminophenyl)amino-anilinofluoran, 3-diethylamino-6-p-(p-diethylaminophenyl)aminoanilinofluoran, 3-diethyl-amino-6-p-(p-dibutylaminophenyl)aminoanilinofluoran, 2,4- dimethyl-6-[(4-dimethylamino)-anilino]fluoran, 3-[(4-dimethylaminophenyl)amino]-5,7-dimethylfluoran, 3,6,6′-tris(dimethyl-amino)spiro[fluorene-9,3′-phthalide], 3,6,6′-tris(diethylamino)spiro[fluorene-9,3′-phthalide], 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3,3-bis(p-dimethylamino-phenyl)phthalide, 3,3-bis-[2-(p-dimethylaminophenyl)-2-(p-methoxyphenyl)vinyl-4,5,6,7-tetrabromophthalide, 3,3-bis-[2-(p-dimethylaminophenyl)-2-(p-methoxyphenyl)vinyl-4,5,6,7-tetrachlorophthalide,3,3-bis[1,1-bis(4-pyrrolidinophenyl)ethylene-2-yl]-4,5,6,7-tetrabromophthalide, 3,3-bis-(1-(4-methoxyphenyl)-1-(4-pyridinophenyl)ethylene-2-yl]-4,5,6,7-tetrachlorophthalide, 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, (1-ethyl-2-methylindol-3-yl)phthalide, 3,3-bis(1-octyl-2-methylindol-3-yl)phthalide, a mixture of -phenyl-4-(4-diethylaminophenyl)-4-(4-methoxyphenyl)-6-methyl-7-dimethylamino-3,1-benzoxazine and 2-phenyl-4-(4-diethylaminophenyl)-4-(4-methoxyphenyl)-8-methyl-7-dimethylamino-3,1-benzoxazine, 4,4′-[1-methylethylidene)-bis(4,1-phenyleneoxy-4,2-quinazolinediyl)]bis[N,N-diethylaniline], bis(N-methyldiphenylamine)-4-yl-(N-butylcarbazolecarbazole)-3-yl-methane and mixtures thereof.

[0186] All of the above-mentioned color-forming compounds can be used alone or as a mixture with other color-forming compounds; or they can also be used with other black-forming compounds.

[0187] Exemplary color-forming compounds are 3-diethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-(3-methylanilino)fluoran, 3-diethylamino-6-methyl-7-(2,4-dimethylanilino)fluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3-dipentylamino-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-isopentylamino)-6-methyl-7-anilinofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3- dibutylamino-7-(2-chloroanilino)fluoran, 3-N-ethyl-p-toluidinyl-6-methyl-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, 2,4-dimethyl-6-[(4-dimethylamino)anilino]fluoran, 3-(4-diethylamino-2-ethoxyphenyl)-3-(1-octyl-2-methylindol-3-yl)-4-azaphthalide, 3,3-bis(p-dimethylamino-phenyl)-6-dimethylaminophthalide and mixtures thereof.

[0188] It is also possible to use solid solutions comprising at least two colour-forming compounds.

[0189] A monophase (or single-phase or guest-host) solid solution has a crystal lattice identical to that of one of its components. One component, acting as a "guest," is embedded in the crystal lattice of another component, acting as a "host." The X-ray diffraction pattern of such a monophase solid solution is essentially the same as that of one of the components, called the "host." Within certain limits, different proportions of the components produce nearly identical results.

[0190] In the literature, the definitions of solid solutions and mixed crystals by different authors such as GH Van't Hoff, AI Kitaigorodsky and A. Whitaker are often contradictory (see, for example, 'Analytical Chemistry of Synthetic Dyes', Chapter 10 / page 269, K. Venkataraman, ed., J. Wiley, New York, 1977).

[0191] Therefore, the terms "single-phase solid solution" or "multiphase solid solution" or "mixed crystal" as defined herein should be taken from the following definitions, which have been adapted to the currently improved state of knowledge of such systems:

[0192] A monophase (or single-phase or guest-host) solid solution has a crystal lattice identical to that of one of its components. One component, acting as a "guest," is embedded in the crystal lattice of another component, acting as a "host." The X-ray diffraction pattern of such a monophase solid solution is essentially the same as that of one of the components, called the "host." Within certain limits, different proportions of the components produce nearly identical results.

[0193] A multiphase solid solution does not have a precise, uniform crystal lattice. A multiphase solid solution differs from a physical mixture of its components in that the crystal lattice of at least one of its components is partially or completely altered. Compared to a physical mixture of the components (which gives an X-ray diffraction pattern that is the accumulation of the patterns seen by the individual components), the signals in the X-ray diffraction pattern of a multiphase solid solution are broadened, shifted, or altered in intensity. In general, different proportions of the components will produce different results.

[0194] A mixed crystal (or solid compound type) solid solution has a precise composition and a uniform crystal lattice, which is different from the crystal lattices of all its components. If different proportions of the components lead to the same result within certain limits, a solid solution with mixed crystals as the main body exists.

[0195] For the avoidance of doubt, it may also be pointed out that, among other things, there may be amorphous structures and mixed aggregates consisting of different particles of different physical types, for example aggregates of different components each in an alkalimorphous form. Such amorphous structures and mixed aggregates cannot be equated with solid solutions or mixed crystals and have different basic properties.

[0196] As detailed above, the single-phase solid solution comprises a plurality of coloured compounds. Suitable colour-forming materials which may be comprised in the solid solution are those given above.

[0197] Of particular interest are the following single-phase solid solutions:

[0198] 3-dibutylamino-6-methyl-7-anilinofluoran and 3-dibutylamino-7-dibenzylaminofluoran;

[0199] 3-dibutylamino-6-methyl-7-anilinofluoran and 3-dibutylamino-7-anilinofluoran;

[0200] 3-dibutylamino-6-methyl-7-anilinofluoran and 3-diethylamino-7-anilinofluoran;

[0201] 3-diethylamino-6-methyl-7-anilinofluoran and 3-diethylamino-7-anilinofluoran;

[0202] 3-dibutylamino-6-methyl-7-anilinofluoran and 3-diethylamino-6-methyl-7-anilinofluoran;

[0203] 3-dibutylamino-6-methyl-7-anilinofluoran and 3-N-isopentyl-N-ethylamino-6-methyl-7-anilinofluoran;

[0204] 3-dibutylamino-6-methyl-7-anilinofluoran and 3-N-2-pentyl-N-ethylamino-6-methyl-7-anilinofluoran;

[0205] 3-dibutylamino-6-methyl-7-anilinofluoran and 3-N-isopropyl-N-ethylamino-6-methyl-7-anilinofluoran;

[0206] 3-dibutylamino-6-methyl-7-anilinofluoran and 3-N-cyclohexylmethyl-N-ethylamino-6-methyl-7-anilinofluoran;

[0207] 3-dibutylamino-6-methyl-7-anilinofluoran and 3-dipropylamino-6-methyl-7-anilinofluoran;

[0208] 3-dibutylamino-6-methyl-7-anilinofluoran and 3-N-2-butyl-N-ethylamino-6-methyl-7-anilinofluoran;

[0209] 3-dibutylamino-6-methyl-7-anilinofluoran and 3-N-cyclohexyl-N-methylamino-6-methyl-7-anilinofluoran;

[0210] 3-dibutylamino-6-methyl-7-anilinofluoran and 3-diethylamino-6-methyl-7-(3-methylanilino)fluoran;

[0211] 3-dibutylamino-6-methyl-7-anilinofluoran and 3-diethylamino-6-methyl-7-(2,4-dimethylanilino)fluoran;

[0212] 3-dibutylamino-6-methyl-7-anilinofluoran and 3-dipentylamino-6-methyl-7-anilinofluoran;

[0213] 3-dibutylamino-6-methyl-7-anilinofluoran and 3-(N-methyl-N-propylamino)-6-methyl-7-anilinofluoran;

[0214] 3-dibutylamino-6-methyl-7-anilinofluoran and 3-diethylamino-6-chloro-7-anilinofluoran;

[0215] 3-dibutylamino-6-methyl-7-anilinofluoran and 3-dibutylamino-7-(2-chloroanilinofluoran;

[0216] 3-dibutylamino-6-methyl-7-anilinofluoran and 3-N-ethyl-p-toluidinyl-6-methyl-7-anilinofluoran;

[0217] 3-dibutylamino-6-methyl-7-anilinofluoran and 3-(N-ethyl-N-tetrahydrofurfurylamino)-6-methyl-7-anilinofluoran;

[0218] 3-dibutylamino-6-methyl-7-anilinofluoran and 3-(N-ethyl-N-isobutylamino)-6-methyl-7-anilinofluoran;

[0219] 3-dibutylamino-6-methyl-7-anilinofluoran and 3-N-ethyl-N-ethoxypropylamino-6-methyl-7-anilinofluoran;

[0220] 3-dibutylamino-6-methyl-7-anilinofluoran and 2,4-dimethyl-6-[(4-dimethylamino)anilino]fluoran;

[0221] 3-N-isopentyl-N-ethylamino-6-methyl-7-anilinofluoran and 3-diethylamino-6-methyl-7-anilinofluoran;

[0222] 3-diethylamino-6-methyl-7-anilinofluoran and 3-N-propyl-N-methylamino-6-methyl-7-anilinofluoran;

[0223] 3-diethylamino-6-methyl-7-(3-methylphenyl)aminofluoran and 3-diethylamino-6-methyl-7-anilinofluoran;

[0224] 3-Dibutylamino-6-methyl-7-anilinofluoran and 3,3-bis(1-octyl-2-methylindol-3-yl)phthalide;

[0225] 3-dibutylamino-6-methyl-7-anilinofluoran and a mixture of 2-phenyl-4-(4-diethylaminophenyl)-4-(4-methoxyphenyl)-6-methyl-7-dimethylamino-3,1-benzoxazole and 2-phenyl-4-(4-diethylaminophenyl)-4-(4-methoxyphenyl)-8-methyl-7-dimethylamino-3,1-benzoxazole;

[0226] 3-Dibutylamino-6-methyl-7-anilinofluoran and 4,4'-[1-methylethylidene)bis(4,1-phenyleneoxy-4,2-quinazolinediyl)]bis[N,N-diethylaniline].

[0227] In the above-mentioned single-phase solid solution, the molar ratio of the first compound is 75 to 99.9 mol%, and the molar ratio of the second compound is 25 to 0.1 mol%.

[0228] An example of a single-phase solid solution comprising two components A and B in the stated ratio is:

[0229] 3-Dibutylamino-6-methyl-7-anilinofluoran (99.9%), 3-diethylamino-6-methyl-7-anilinofluoran (0.1%);

[0230] 3-Dibutylamino-6-methyl-7-anilinofluoran (99%), 3-diethylamino-6-methyl-7-anilinofluoran (1%);

[0231] 3-Dibutylamino-6-methyl-7-anilinofluoran (95%), 3-diethylamino-6-methyl-7-anilinofluoran (5%);

[0232] 3-dibutylamino-6-methyl-7-anilinofluoran (90%) and 3-N-2-pentyl-N-ethylamino-6-methyl-7-anilinofluoran (10%);

[0233] 3-dibutylamino-6-methyl-7-anilinofluoran (95%) and 3-N-2-pentyl-N-ethylamino-6-methyl-7-anilinofluoran (5%);

[0234] 3-dibutylamino-6-methyl-7-anilinofluoran (90%) and 3-N-isopropyl-N-ethylamino-6-methyl-7-anilinofluoran (10%);

[0235] 3-dibutylamino-6-methyl-7-anilinofluoran (95%) and 3-N-isopropyl-N-ethylamino-6-methyl-7-anilinofluoran (5%);

[0236] 3-dibutylamino-6-methyl-7-anilinofluoran (90%) and 3-N-cyclohexylmethyl-N-ethylamino-6-methyl-7-anilinofluoran (10%);

[0237] 3-dibutylamino-6-methyl-7-anilinofluoran (95%) and 3-N-cyclohexylmethyl-N-ethylamino-6-methyl-7-anilinofluoran (5%);

[0238] 3-dibutylamino-6-methyl-7-anilinofluoran (90%) and 3-dipropylamino-6-methyl-7-anilinofluoran (10%);

[0239] 3-dibutylamino-6-ethyl(enethyl)-7-anilinofluoran (95%) and 3-dipropylamino-6-methyl-7-anilinofluoran (5%);

[0240] 3-dibutylamino-6-methyl-7-anilinofluoran (90%) and 3-N-2-butyl-N-ethylamino-6-methyl-7-anilinofluoran (10%);

[0241] 3-dibutylamino-6-methyl-7-anilinofluoran (95%) and 3-N-2-butyl-N-ethylamino-6-methyl-7-anilinofluoran (5%);

[0242] 3-dibutylamino-6-methyl-7-anilinofluoran (90%) and 3-diethylamino-6-methyl-7-anilinofluoran (10%);

[0243] 3-dibutylamino-6-methyl-7-anilinofluoran (85%) and 3-diethylamino-6-methyl-7-anilinofluoran (15%);

[0244] 3-dibutylamino-6-methyl-7-anilinofluoran (80%) and 3-diethylamino-6-methyl-7-anilinofluoran (20%);

[0245] 3-dibutylamino-6-methyl-7-anilinofluoran (95%) and 3-N-isopentyl-N-ethylamino-6-methyl-7-anilinofluoran (5%);

[0246] 3-dibutylamino-6-methyl-7-anilinofluoran (90%) and 3-N-isopentyl-N-ethylamino-6-methyl-7-anilinofluoran (10%);

[0247] 3-dibutylamino-6-methyl-7-anilinofluoran (80%) and 3-N-isopentyl-N-ethylamino-6-methyl-7-anilinofluoran (20%);

[0248] 3-dibutylamino-6-methyl-7-anilinofluoran (90%) and 3-N-cyclohexyl-N-methylamino-6-methyl-7-anilinofluoran (10%);

[0249] 3-Diethylamino-6-methyl-7-anilinofluoran (90%) and 3-N-isopentyl-N-ethylamino-6-methyl-7-anilinofluoran (10%);

[0250] 3-Diethylamino-6-methyl-7-anilinofluoran (80%) and 3-N-isopentyl-N-ethylamino-6-methyl-7-anilinofluoran (20%);

[0251] 3-Diethylamino-6-methyl-7-anilinofluoran (20%) and 3-N-isopentyl-N-ethylamino-6-methyl-7-anilinofluoran (80%);

[0252] 3-Diethylamino-6-methyl-7-anilinofluoran (10%) and 3-N-isopentyl-N-ethylamino-6-methyl-7-anilinofluoran (90%);

[0253] 3-Diethylamino-6-methyl-7-anilinofluoran (90%) and 3-N-propyl-N-methylamino-6-methyl-7-anilinofluoran (10%);

[0254] 3-Diethylamino-6-methyl-7-anilinofluoran (80%) and 3-N-propyl-N-methylamino-6-methyl-7-anilinofluoran (20%);

[0255] 3-Diethylamino-6-methyl-7-anilinofluoran (20%), 3-N-propyl-N-methylamino-6-methyl-7-anilinofluoran (80%);

[0256] 3-Diethylamino-6-methyl-7-anilinofluoran (10%) and 3-N-propyl-N-methylamino-6-methyl-7-anilinofluoran (90%);

[0257] 3-diethylamino-6-methyl-7-anilinofluoran (10%) and 3-diethylamino-6-methyl-7-(3-methylphenyl)aminofluoran (90%);

[0258] 3-diethylamino-6-methyl-7-anilinofluoran (20%) and 3-diethylamino-6-methyl-7-(3-methylphenyl)aminofluoran (80%);

[0259] 3-Dibutylamino-6-methyl-7-anilinofluoran (90%) and 3,3-bis(1-octyl-2-methylindol-3-yl)phthalide (10%);

[0260] 3-Diethylamino-6-methyl-7-anilinofluoran (80%) and 3,3-bis(1-octyl-2-methylindol-3-yl)phthalide (20%);

[0261] 3-Dibutylamino-6-methyl-7-anilinofluoran (90%) and a mixture of 2-phenyl-4-(4-diethylaminophenyl)-4-(4-methoxyphenyl)-6-methyl-7-dimethylamino-3,1-benzoxazine and 2-phenyl-4-(4-diethylaminophenyl)-4-(4-methoxyphenyl)-8-methyl-7-dimethylamino-3,1-benzoxazine (10%);

[0262] 3-Dibutylamino-6-methyl-7-anilinofluoran (80%) and a mixture of 2-phenyl-4-(4-diethylaminophenyl)-4-(4-methoxyphenyl)-6-methyl-7-dimethylamino-3,1-benzoxazine and 2-phenyl-4-(4-diethylaminophenyl)-4-(4-methoxyphenyl)-8-methyl-7-dimethylamino-3,1-benzoxazine (20%);

[0263] 3-Dibutylamino-6-methyl-7-anilinofluoran (90%) and 4,4′-[1-methylethylidene)bis(4,1-phenyleneoxy-4,2-quinazolinediyl)bis(N,N-diethylaniline] (10%);

[0264] 3-Dibutylamino-6-methyl-7-anilinofluoran (80%) and 4,4′-[1-methylethylidene)bis(4,1-phenyleneoxy-4,2-quinazolinediyl)]bis[N,N-diethylaniline] (20%).

[0265] The single-phase solid solutions can be used alone or as a mixture with other color-forming compounds, such as triphenylmethane, lactones, fluoranes, benzoxazines and spiropyrans; or they can also be used with other black-forming compounds. Examples of such other color-forming compounds are given above.

[0266] Single-phase solid solution can be prepared by several methods. One such method is recrystallization, wherein the physical mixture of the desired components is dissolved in a suitable solvent or solvent mixture under heating or without heating. Suitable solvents include but are not limited to toluene, benzene, xylene, dichlorobenzene, chlorobenzene, 1,2-ethylene dichloride, methanol, ethanol, isopropanol, n-butanol, acetonitrile, dimethylformamide or these solvents with each other and with a mixture of water. The single-phase solid solution is then separated by crystallization from a solvent or solvent mixture. This can be achieved by cooling, standing, adding another solvent to promote crystallization or by concentrating with standard measures such as distillation, steam distillation and vacuum distillation. When separating the single-phase solid solution by concentration, doing so in the presence of a small amount of alkali may be advantageous for improving the visual properties of the separated product.

[0267] Alternatively, a single-phase solid solution can be prepared from a mixture of suitable starting materials. This technique can be used to produce a mixture of two or more fluorans or phthalides. For example, a mixture of two fluorans is produced by replacing a single starting material with two similar materials to have the same total molar concentration in the reaction. In the case of the fluorans, these starting materials are aminophenols, phthalic anhydrides and derivatives of keto acids and diphenylamines.

[0268] In addition, the heat-sensitive recording material may contain a previously known developer unless the developer interferes with the color-forming properties of the resulting heat-sensitive material. Examples of such developers include, but are not limited to; 4,4′-isopropylidene bisphenol, 4,4′-sec-butylidene bisphenol, 4,4′-cyclohexylidene bisphenol, 2,2-bis-(4-hydroxyphenyl)-4-methylpentane, 2,2-dimethyl-3,3-bis(4-hydroxyphenyl)butane, 2,2′-dihydroxybiphenyl, 1-phenyl-1,1-bis(4-hydroxyphenyl)butane, 4-phenyl-2,2-bis(4-hydroxyphenyl)-4-methylpentane. 4-Hydroxyphenyl)butane, 1-phenyl-2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4′-hydroxy-3′-methylphenyl)-4-methylpentane, 2,2-bis(4′-hydroxy-3′-tert-butylphenyl)-4-methylpentane, 4,4′-sec-butylidene-bis(2-methylphenol), 4,4′-isopropylidene-bis(2-tert-butylphenol), 2,2-bis(4′-hydroxy-3′-isopropylphenyl)-4-methylpentane 4,4-bis(4′-hydroxyphenyl)pentanoic acid allyl ester, 4,4-bis(4′-hydroxyphenyl)pentanoic acid propargyl ester, 4,4-bis(4′-hydroxyphenyl)pentanoic acid n-propyl ester, 2,4-bis(phenylsulfonyl)phenol, 2-(4-methylsulfonyl)-4-(phenylsulfonyl)phenol, 2-(phenylsulfonyl)-4-(4-methylsulfonyl)phenol, 2,4-bis(4-methylphenyl)pentanoic acid 2,2-dimethyl-3,3-di(4-hydroxyphenyl)pentane, 2,2-di(4-hydroxyphenyl)hexane, 4,4′-dihydroxydiphenyl sulfide, 1,7-bis(4-hydroxyphenylthio)-3,5-dioxaheptane, 2,2′-bis(4-hydroxyphenylthio)diethyl ether, 4,4′-dihydroxy-3,3′-dimethylphenyl sulfide;4-hydroxybenzoic acid benzyl ester, 4-hydroxybenzoic acid ethyl ester, 4-hydroxybenzoic acid propyl ester, 4-hydroxybenzoic acid isopropyl ester, 4-hydroxybenzoic acid butyl ester, 4-hydroxybenzoic acid isobutyl ester, 4,4'-dihydroxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-methyl diphenyl sulfone, 4-hydroxy-4'-isopropoxy diphenyl sulfone, 4-hydroxy-4'-butoxy diphenyl sulfone, 4,4'-dihydroxy-3, 3′-diallyl diphenyl sulfone, 3,4-dihydroxy-4′-methyl diphenyl sulfone, 4,4′-di-hydroxy-3,3′,5,5′-tetrabromodiphenyl sulfone, 4,4′-bis(p-toluenesulfonylaminocarbonylamino)diphenylmethane, N-p-tolylsulfonyl-N′-phenylurea, dimethyl 4-hydroxyphthalate, dicyclohexyl 4-hydroxyphthalate, diphenyl 4-hydroxyphthalate, 4-[2-(4- salicylic acid, 3-(α-methylbenzyl) salicylic acid, 3-phenyl-5-(α,α-dimethylbenzyl) salicylic acid, 3,5-di-α-methylbenzyl salicylic acid; metal salts of salicylic acid, 2-benzylsulfonylbenzoic acid, 3-cyclohexyl-4-hydroxybenzoic acid, zinc benzoate, zinc 4-nitrobenzoate, 4-(4′-phenoxybutyloxy) )phthalic acid, 4-(2′-phenoxyethoxy)phthalic acid, 4-(3′-phenylpropoxy)phthalic acid, 5-nitro-isophthalic acid mono(2-hydroxyethyl ester), 5-benzyloxycarbonylisophthalic acid, 5-(1′-phenylethylsulfonyl)isophthalic acid, bis(1,2-dihydro-1,5-dimethyl-2-phenyl-3H-pyrazol-3-one-O)bis(thiocyanato-N)zinc and mixtures thereof.

[0269] In addition, the exemplary heat-sensitive recording material may contain a sensitizer. Representative examples of the sensitizer are stearamide, hydroxymethyl stearamide, p-benzylbiphenyl, m-terphenyl, 2-benzyloxynaphthalene, 4-methoxybiphenyl, dibenzyl oxalate, di(4-methylbenzyl oxalate), di(4-chlorobenzyl oxalate), dimethyl phthalate, dibenzyl terephthalate, dibenzyl isophthalate, 1,2-diphenoxyethane, 1,2-bis(4-methylphenoxy)ethane, 1,2-bis(3-methyl-phenoxy)ethane, 4,4′-dimethylbiphenyl, 1-hydroxy-2-naphthalene, acid phenyl ester, 4-methylphenyl biphenyl ether, 1,2-bis(3,4-dimethylphenyl)ethane, 2,3,5,6-4′-methyldiphenylmethane, 1,4-diethoxynaphthalene, 1,4-diacetoxybenzene, 1,4-dipropoxybenzene, o-xylylene-bis(phenyl ether), 4-(m-methylphenoxymethyl)biphenyl, p-hydroxyacetanilide, p-hydroxybutyric acid anilide, p-hydroxynonanoic acid anilide, p-hydroxylauric acid anilide, p-hydroxyoctadecanoic acid anilide, N-phenyl-benzenesulfonamide and the following sensitizer

[0270]

[0271] wherein R and R' are the same as or different from each other and each represents a C1-C6 alkyl group.

[0272] Examples of R and R' are methyl, ethyl, n-propyl or isopropyl and n-butyl, sec-butyl or tert-butyl.

[0273] The substituents R and R' are identical to or different from one another and are each preferably C1-C4-alkyl, in particular methyl or ethyl, especially ethyl.

[0274] The above-mentioned sensitizers are known or can be prepared according to known methods.

[0275] In addition, the exemplary heat-sensitive recording material may contain a stabilizer. Representative stabilizers for heat-sensitive recording materials include 2,2′-methylene-bis(4-methyl-6-tert-butylphenol), 2,2′-methylene-bis(4-ethyl-6-tert-butylphenol), 4,4′-butylidene-bis(3-methyl-6-tert-butylphenol), 4,4′-thio-bis(2-tert-butyl-5-methylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,1,3-tris(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane, bis(3-tert-butyl-4-hydroxy-6-methylphenyl)sulfone. , bis(3,5-dibromo-4-hydroxyphenyl)sulfone, 4,4′-sulfinylbis(2-tert-butyl-5-methylphenol), bis(4,6-di-tert-butylphenyl)phosphate, 2,2′-methylene ester and alkali metal, ammonium and polyvalent metal salts thereof, 4-benzyloxy-4′-(2-methylglycidyloxy)diphenylsulfone, 4,4′-diglycidyloxydiphenylsulfone, 1,4-diglycidyloxybenzene, 4-[α-(hydroxymethyl)benzyloxy]4-hydroxydiphenylsulfone, metal salts of p-nitrobenzoic acid, metal salts of monobenzyl phthalate, metal salts of cinnamic acid and mixtures thereof.

[0276] Preferred stabilizers are 4,4′-butylidene-bis(3-methyl-6-tert-butylphenol), 4,4′-thio-bis(2-tert-butyl-5-methylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,1,3-tris(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane, 4-benzyloxy-4′-(2-methylglycidyloxy)diphenyl sulfone and mixtures thereof.

[0277] Exemplary heat-sensitive recording materials can be prepared according to conventional methods. For example, at least one color-forming compound, at least one developer and, if necessary, at least one sensitizer are pulverized separately in water or a suitable dispersion medium such as aqueous polyvinyl alcohol to form an aqueous dispersion or other dispersion. If necessary, a stabilizer is treated in the same manner. The fine particle dispersions thus obtained are combined and then mixed with conventional amounts of binders, fillers and lubricants.

[0278] Representative binders for thermosensitive recording materials include polyvinyl alcohol (completely and partially hydrolyzed), carboxyl-, amide-, sulfonic- and butyral-modified polyvinyl alcohols, cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose and acetyl cellulose, styrene-maleic anhydride copolymers, styrene-butadiene copolymers, polyvinyl chloride, polyvinyl acetate, polyacrylamide, polyamide resins and mixtures thereof.

[0279] Exemplary fillers that may be used include calcium carbonate, kaolin, calcined kaolin, aluminum hydroxide, talc, titanium dioxide, zinc oxide, silicon dioxide, polystyrene resin, urea-formaldehyde resin, hollow plastic pigments, and mixtures thereof.

[0280] Representative lubricants for heat-sensitive recording materials include dispersions or emulsions of stearamide, methylene bisstearamide, polyethylene, carnauba wax, paraffin wax, zinc stearate or calcium stearate, and mixtures thereof.

[0281] If necessary, other additives may also be used, such as fluorescent brighteners and ultraviolet light absorbers.

[0282] The coating composition thus obtained can be applied to suitable substrates such as paper, plastic sheets and resin coated paper and used as a thermosensitive recording material.The embodiments herein can be used in other end use applications using color forming materials such as temperature indicating materials.

[0283] The coating amount is usually between 2 and 10 g / m 2 range, most commonly between 4 and 8 g / m 2 within the range.

[0284] The recording material comprising such a thermosensitive coloring layer may further comprise a protective layer and, if necessary, an undercoat layer. The undercoat layer may be interposed between the substrate and the thermosensitive coloring layer.

[0285] The protective layer generally contains a water-soluble resin to protect the heat-sensitive coloring layer. If necessary, the protective layer may contain a combination of a water-soluble resin and a water-insoluble resin.

[0286] As such resin, conventional resins can be used. Specific examples are: polyvinyl alcohol; starch and starch derivatives; cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose and ethylcellulose; sodium polyacrylate; polyvinyl pyrrolidone; polyacrylamide / acrylate copolymer; acrylamide / acrylate / methacrylic acid copolymer; alkali metal salts of styrene / maleic anhydride copolymer; alkali metal salts of isobutylene / maleic anhydride copolymer; polyacrylamide; sodium alginate; gelatin; casein; water-soluble polyester and carboxyl-modified polyvinyl alcohol.

[0287] The protective layer may further contain a water-resistant agent such as polyamide resin, melamine resin, formaldehyde, glyoxal or chrome alum.

[0288] Furthermore, the protective layer may contain fillers such as finely dispersed inorganic powders such as calcium carbonate, silicon dioxide, zinc oxide, titanium dioxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, surface-treated calcium or silicon dioxide, or finely dispersed organic powders such as urea-formaldehyde resins, styrene / methacrylic acid copolymers or polystyrene.

[0289] The primer layer generally contains a binder resin and a filler as its main components.

[0290] Specific examples of the binder resin for the primer layer are: polyvinyl alcohol; starch and starch derivatives; cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose and ethylcellulose; sodium polyacrylate; polyvinyl pyrrolidone; polyacrylamide / acrylate copolymer; acrylamide / acrylate / methacrylic acid copolymer; alkali metal salts of styrene / maleic anhydride copolymer; alkali metal salts of isobutylene / maleic anhydride copolymer; polyacrylamide; sodium alginate; gelatin; casein; water-soluble polymers such as water-soluble polyesters and carboxyl-modified polyvinyl alcohol; polyvinyl acetate; polyurethane; styrene / butadiene copolymer; polyacrylic acid; polyacrylate; vinyl chloride / vinyl acetate copolymer; polybutyl methacrylate; ethylene / vinyl acetate copolymer and styrene / butadiene acrylic acid derivative copolymer.

[0291] Specific examples of fillers for the base coat are finely dispersed inorganic powders such as calcium carbonate, silica, zinc oxide, titanium dioxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, surface-treated calcium, silica or calcined clay (e.g., Ansilex, Engelhard Corp.), and finely dispersed organic powders such as urea-formaldehyde resins, styrene / methacrylic acid copolymers and polystyrene.

[0292] Furthermore, the primer layer may contain a water-proofing agent. Examples of such a water-proofing agent are given above.

[0293] In particular, embodiments herein provide excellent resistance to plasticizers, oils, and heat aging while exhibiting improved background whiteness.

[0294] In addition, examples of suitable second non-phenolic developer compounds are shown in U.S. Patent No. 6,624,117 B1, issued September 23, 2003, which is incorporated herein in its entirety.

[0295] Thermal recording materials

[0296] The thermosensitive recording material of the embodiment herein can be used for any purpose as long as it is a recording material containing the color former, the first non-phenolic developer and the second non-phenolic developer as described herein, and, for example, can be used as a thermosensitive recording material or a pressure-sensitive copy material.

[0297] In the recording material, the ratio of the compound of the non-phenolic developer to the coupler used may be 0.01 to 10 parts by mass, such as 0.5 to 10 parts by mass, for example 1.0 to 5 parts by mass, relative to 1 part by mass of the coupler.

[0298] Other components in recording materials

[0299] In an exemplary embodiment, in addition to the color former and the non-phenolic developer, the recording material may further contain one or more of a developer, an image stabilizer, a sensitizer, a filler, a dispersant, an antioxidant, a sensitizer, a release agent, a defoaming agent, a light stabilizer, a fluorescent whitening agent, etc. known in the art as needed. The amount of each component used may be in the range of about 0.1 to about 15 parts by mass, for example, 1 to 10 parts by mass, relative to 1 part by mass of the color former.

[0300] These agents may be contained in the color development layer or may be contained in any layer, for example, when composed of a multilayer structure, they may be contained in a protective layer. In particular, when a cover coating or a primer is provided on the upper and / or lower part of the color development layer, these layers may contain antioxidants, light stabilizers, etc. In addition, these antioxidants or light stabilizers may be encapsulated in these layers in the form of microcapsules as needed.

[0301] Color former

[0302] The example of the color former used in the recording material described herein may include, but is not limited to, fluoran, phthalide, lactam, triphenylmethane, phenothiazine and spiropyran leuco dye. Any color former that forms color by contacting with a developer that is an acidic substance can be used. In addition, these color formers can certainly be used alone to produce a recording material with a color to be formed. Alternatively, two or more color formers can also be used in combination. For example, a color former (red, blue and green) color former or a black former can be mixed and used to produce a recording material showing true black.

[0303] Examples of fluoran couplers include 3,3-bis(p-dimethylaminophenyl)phthalide, 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis(p-dimethylaminophenyl)-6-diethylaminophthalide, 3,3-bis(p-dimethylaminophenyl)-6-chlorophthalide, 3,3-bis(p-dibutylaminophenyl)-phthalide, 3-cyclohexylamino-6-chlorofluoran, 3-dimethylamino-5,7-dimethylfluoran, 3-N-methyl-N-isopropyl 3-diethylamino-7-chlorofluoran, 3-diethylamino-6,8-dimethylfluoran, 3-diethylamino-7-methylfluoran, 3-diethylamino-7,8-benzofluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3-dibutylamino-6-methyl-7-bromofluoran, 3-(N-p-tolyl-N-ethylamino)-6-methyl-7-anilinofluoran, 3-pyrrolidino-6-methylamino-7-anilinofluoran, 2-{N-(3′-trifluoromethylphenyl)amino}-6-diethylaminofluoran, 2-{3,6-bis(diethylamino)-9-(o-chloroanilino)xanthenylbenzoic acid lactam}, 3-diethylamino-6-methyl-7-(m-trichloromethylanilino)fluoran, 3-diethylamino-7-(o-chloroanilino)fluoran, 3-dibutylamino fluoran, 3-(N,N-diethylamino)-5-methyl-7-(N,N-dibenzylamino)fluoran, 3-(N,N-diethylamino)-7-(2′,4′-dimethylanilino)fluoran, 3-(N,N-diethylamino)-5-methyl-7-(N,N-dibenzylamino)fluoran, 3-(N,N-diethylamino)-7-(N,N-diethylamino)-6-methyl-7-(2′,4′-dimethylanilino)fluoran, 3-(N,N-diethylamino)-7-(N,N-diethylamino)-6-methyl-7-(2′,4′-dimethylanilino)fluoran, 3-(N,N-diethylamino)-5-methyl-7-(N,N-dibenzylamino)fluoran, 3-(N,N-diethylamino)-7-(N,fluoran, 3-(N-ethyl-N-isobutylamino)-6-methyl-7-anilinofluoran, 3-(N-ethyl-N-propylamino)-6-methyl-7-anilinofluoran, 3-(N-methyl-N-propylamino)-6-methyl-7-anilinofluoran, 3-(N-ethyl-N-isopentylamino)-6-methyl-7-anilinofluoran, 3-(N-ethyl-N-toluidino)-6-methyl-7-anilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-piperidino-6-methyl-7-anilinofluoran, 3-dimethylamino-7-(trifluoromethylanilino)fluoran, 3-dipentylamino-6-methyl-7-anilinofluoran, 3-(N-ethyl-N-isopentylamino)-6-methyl-7-anilinofluoran, fluoran, 3-diethylamino-5-methyl-7-benzylaminofluoran, 3-diethylamino-5-chlorofluoran, 3-diethylamino-6-(N,N′-dibenzylamino)fluoran, 3,6-dimethoxyfluoran, 2,4-dimethyl-6-(4-dimethylaminophenyl)aminofluoran, 3-diethylamino-7-(m-trifluoromethylanilino)fluoran, 3-diethylamino-6-methyl-7-octylaminofluoran, 3-diethylamino-7-methyl-7-(m-tolylamino)fluoran, 3-diethylamino-6-methyl-7-(2,4-dimethylphenylamino)fluoran, 3-diethylamino-7-(o-fluoroanilino)fluoran, 3-diphenylamino-6-methyl-7-anilinofluoran, benzoyl leuco-methylene blue, 6'-chloro-8'-methoxy-benzoindoline-spiropyran, 6'-bromo-3'-methoxy-benzoindoline-spiropyran, 3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-chlorophenyl)phthalide, 3-(2'-hydroxy-4'-diethylaminophenyl)-3-(2'-methoxy-5'-nitrophenyl)phthalide, 3-(2'-hydroxy-4'-diethylaminophenyl)-3-(2'-methoxy-5'-nitrophenyl)phthalide, 3-(2'-methoxy-5'-methylphenyl)phthalide, 3-(2'-methoxy-4'-dimethylaminophenyl)-3-(2'-hydroxy-4'-chloro-5'-methylphenyl)phthalide, 3-morpholino-7-(N-propyl-trifluoromethylanilino)fluoran, 3-pyrrolidino-7-trifluoromethylanilinofluoran, 3-diethylamino-5-chloro-7-(N-benzyl-trifluoromethylanilino)fluoran, 3-pyrrolidino-7-(di-p-chlorophenyl)methylaminofluoran, 3-diethylamino-5-chloro-7-(α-phenylethylamino)fluoran, 3-( fluoran, 3-diethylamino-7-(o-methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7-(α-phenylethylamino)fluoran, 3-diethylamino-7-piperidinofluoran, 2-chloro-3-(N-methyltoluidino)-7-(p-butylanilino)fluoran, 3-(N-methyl-N-isopropylamino)-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3-dipentylamino-6-methyl-7-anilinofluoran, 3,6-bis(di fluorenespiro (9,3′)-6′-dimethylaminophthalide, 3-(N-benzyl_N-cyclohexylamino)-5,6-benzo-7-α-naphthylamino_4′-bromofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-N-ethyl-N-(2-ethoxypropyl)amino-6-methyl-7-anilinofluoran, 3-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-m-trimethylphenylamino_4′,5′-benzofluoran and -(N-ethyl-p-toluidinyl)-7-(methylphenylamino)fluoran.

[0304] Among these couplers, exemplary examples may include 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3-cyclohexylamino-6-chlorofluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-6,8-dimethylfluoran, 3-diethylamino-7-methylfluoran, 3-diethylamino-7,8-benzofluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3-dibutylamino-6-methyl-7-bromofluoran, 3-diethylamino-7-bromofluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3-diethylamino-7-methylfluoran, 3-diethylamino-6-methyl-7-bromofluoran, 3-diethylamino-7-methylfluoran, 3-diethylamino-7-methylfluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3-diethylamino-7-methylfluoran, 3-diethylamino-7-methylfluoran, 3-diethylamino-6-methyl-7-bromofluoran, 3-diethylamino-7-methyl ... -7-(o-chloroanilino)fluoran, 3-dibutylamino-7-(o-chloroanilino)fluoran, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluoran, 3-(N,N-diethylamino)-5-methyl-7-(N,N-dibenzylamino)fluoran, 3-(N,N-diethylamino)-7-(N,N-dibenzylamino)fluoran, 3-(N-ethyl-N-isobutylamino)-6-methyl-7-anilinofluoran, 3-(N-methyl-N- 3-(N-ethyl-N-isopentylamino)-6-methyl-7-anilinofluoran, 3-(N-ethyl-N-toluidinyl)-6-methyl-7-anilinofluoran, 3-(N-ethoxypropyl-N-ethylamino)-6-methyl-7-anilinofluoran, 3-dibutylamino-7-(o-fluoroanilino)fluoran, 3-diethylamino-7-(m-trifluoromethylanilino)fluoran, 3-diethylamino-6-methyl -7-octylaminofluoran, 3-diethylamino-6-methyl-7-(m-tolylamino)fluoran, 3-diethylamino-7-(o-fluoroanilino)fluoran, 3-diphenylamino-6-methyl-7-anilinofluoran, benzoylleucomethylene blue, 3-dibutylamino-6-methyl-7-anilinofluoran, 3-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-7-anilinofluoran and 3-(N-ethyl-p-toluidinyl)-7-(methylphenylamino)fluoran.

[0305] dye

[0306] Furthermore, examples of the near-infrared absorbing dye include 3-[4-[4-(4-anilino)-anilino]anilino]-6-methyl-7-chlorofluoran, 3,3-bis[2-(4-dimethylaminophenyl)-2-(4-methoxyphenyl)vinyl]-4,5,6,7-tetrachlorophthalide, and 3,6,6′-tris(dimethylamino)spiro(fluorene-9,3′-phthalide).

[0307] The exemplary non-phenolic developers described herein are suitable for use as the main developer in the heat-sensitive recording material, and these compounds can be used alone or these compounds can be used together with various known developers. In certain embodiments, the ratio between them is arbitrary.

[0308] Other color developers

[0309] Examples of other color developers may specifically include the following: bisphenol compounds such as bisphenol A, 4,4′-sec-butylidene bisphenol, 4,4′-cyclohexylidene bisphenol, 2,2′-bis(4-hydroxyphenyl)-3,3′-dimethylbutane, 2,2′-dihydroxybiphenyl, bis(4-hydroxybenzoic acid) pentamethylene ester, 2,2-dimethyl-3,3-di(4-hydroxyphenyl)pentane, 2,2-di(4-hydroxyphenyl)hexane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 4,4′-(1-phenylethylidene)bisphenol, 4,4′-ethylidene bisphenol. , (hydroxyphenyl) methylphenol, 2,2'-bis(4-hydroxy-3-phenyl-phenyl) propane, 4,4'-(1,3-phenylene diisopropylidene) bisphenol, 4,4'-(1,4-phenylene diisopropylidene) bisphenol and 2,2-bis(4-hydroxyphenyl) butyl acetate; sulfur-containing bisphenol compounds such as 4,4'-dihydroxydiphenyl sulfide, 1,7-bis(4-hydroxyphenylthio)-3,5-dioxaheptane, 2,2'-bis(4-hydroxyphenylthio) diethyl ether and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide; 4-hydroxybenzoic acid esters such as 4-hydroxybenzoic acid benzyl ester, 4-hydroxybenzoic acid ethyl ester, 4-hydroxybenzoic acid butyl ester 4-hydroxybenzoic acid propyl ester, isopropyl 4-hydroxybenzoate, butyl 4-hydroxybenzoate, isobutyl 4-hydroxybenzoate, benzyl chlorobenzoate, methyl benzyl 4-hydroxybenzoate and diphenylmethyl 4-hydroxybenzoate; metal salts of benzoic acid such as zinc benzoate and zinc 4-nitrobenzoate, salicylic acid such as 4-[2-(4-methoxyphenoxy)ethoxy]salicylic acid; metal salts of salicylic acid such as zinc salicylate and bis[zinc 4-(octyloxycarbonylamino)-2-hydroxybenzoate]; hydroxy sulfones such as 4,4′-dihydroxydiphenyl sulfone, 2,4′-dihydroxydiphenyl sulfone, 4-hydroxy-4′-methyldiphenyl sulfone, 4-hydroxy-4′-isopropoxydiphenyl sulfone , 4-hydroxy-4′-butoxydiphenyl sulfone, 4,4′-dihydroxy-3,3′-diallyldiphenyl sulfone, 3,4-dihydroxy-4′-methyldiphenyl sulfone, 4,4′-dihydroxy-3,3′,5,5′-tetrabromodiphenyl sulfone, 4-allyloxy-4′-hydroxydiphenyl sulfone, 2-(4-hydroxyphenylsulfonyl)phenol, 4,4′-sulfonylbis[2-(2-propenyl)]phenol, 4-[[4-(propoxy)phenyl}sulfonyl]phenol, 4-[{4-(allyloxy)phenyl}sulfonyl]phenol, 4-[{4-(benzyloxy)phenyl}sulfonyl]phenol and 2,4-bis(phenylsulfonyl)-5-methyl-phenol;2,4'-dihydroxydiphenyl sulfone (BPS2,4'), bis-(4-hydroxyphenyl) sulfone (BPS 4,4'), bis(3-allyl-4-hydroxyphenyl) sulfone (TG-SA), B-TUM, SZ11 0, polyvalent metal salts of hydroxysulfones such as 4-phenylsulfonylphenoxy-zinc magnesium, -aluminum and -titanium; 4-hydroxyphthalic acid diesters such as dimethyl 4-hydroxyphthalate, dicyclohexyl 4-hydroxyphthalate and diphenyl 4-hydroxyphthalate; hydroxynaphthoic acid esters such as 2-hydroxy-6-carboxynaphthalene; trihalomethyl sulfones such as tribromomethylphenyl sulfone; sulfonylureas such as 4,4′-bis(p-toluenesulfonylaminocarbonylamino)diphenylmethane and N-(4-methylphenylsulfonyl)-N′-(3-(4-methylphenylsulfonyloxy)phenyl)urea; hydroxyacetophenone, p-phenylphenol, 4-hydroxyphenylacetic acid benzyl ester, p-benzylphenol, hydroquinone-monobenzyl ether , 2,4-dihydroxy-2′-methoxybenzanilide, tetracyanoquinodimethanes, N-(2-hydroxyphenyl)-2-[(4-hydroxyphenyl)thio]acetamide, N-(4-hydroxyphenyl)-2-[(4-hydroxyphenyl)thio]acetamide, 4-hydroxybenzenesulfonylanilide, 4′-hydroxy-4-methylbenzenesulfonylanilide, 4,4′-bis(4-methyl-3-phenoxycarbonyl))aminophenylureido))diphenylsulfone, 3-(3-phenylureido)benzenesulfonylanilide, octadecyl phosphoric acid and dodecyl phosphoric acid; and a cross-linked diphenyl sulfone compound represented by the following formula or a mixture thereof:

[0310]

[0311] (b represents an integer from 0 to 6)

[0312] Among them, preferred examples thereof include 4-hydroxy-4′-isopropoxydiphenyl sulfone and a cross-linked diphenyl sulfone compound or a mixture thereof.

[0313] Stabilizer

[0314] Examples of the image stabilizer may include: epoxy-containing diphenyl sulfones such as 4-benzyloxy-4′-(2-methylglycidyloxy)-diphenyl sulfone and 4,4′-diglycidyloxydiphenyl sulfone; 1,4-diglycidyloxybenzene, 4-[α-(hydroxymethyl)benzyloxy]-4′-hydroxydiphenyl sulfone, 2-propanol derivatives, salicylic acid derivatives, metal salts (particularly zinc salts) of hydroxynaphthoic acid derivatives, metal salts of 2,2-methylenebis(4,6-tert-butylphenyl)phosphate, and other water-insoluble zinc compounds; hindered phenol compounds such as 2,2-bis(4′-hydroxy-3′,5′-dibromophenyl)propane; Alkane, 4,4′-sulfonylbis(2,6-dibromophenol), 4,4′-butylidene(6-tert-butyl-3-methylphenol), 2,2′-methylene-bis(4-methyl-6-tert-butylphenol), 2,2′-methylene-bis(4-ethyl-6-tert-butylphenol), 2,2′-di-tert-butyl-5,5′-dimethyl-4,4′-sulfonyldiphenol, 1,1,3-tris(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane and 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, as well as linear phenolic resin compounds, epoxy resins and UU (a developer manufactured by CHEMIPRO KASEI).

[0315] Examples further include cross-linked diphenyl sulfone compounds represented by the following formula or mixtures thereof:

[0316]

[0317] (b represents an integer from 0 to 6)

[0318] An exemplary image stabilizer is a compound that is solid at room temperature, such as a compound that has a melting point of 60° C. or higher and is poorly soluble in water.

[0319] Sensitizer

[0320] Examples of the sensitizer may include: higher fatty amides such as stearamide, stearylanilide and palmitamide; amides such as benzamide, acetoacetanilide, thioacetanilide acrylamide, ethylenediamine, o-toluenesulfonamide and p-toluenesulfonamide; phthalic acid diesters such as dimethyl phthalate, dibenzyl isophthalate, dimethyl isophthalate, dimethyl terephthalate, diethyl isophthalate, diphenyl isophthalate, terephthalate; dibenzyl formate; oxalic acid diesters, such as dibenzyl oxalate, di(4-methylbenzyl oxalate), di(4-chlorobenzyl oxalate), a mixture of equal amounts of dibenzyl oxalate and di(4-chlorobenzyl oxalate), and a mixture of equal amounts of di(4-chlorobenzyl oxalate) and di(4-methylbenzyl oxalate); bis(tert-butylphenol), such as 2,2′-methylenebis(4-methyl-6-tert-butylphenol) and 4,4′-methylene-bis-2,6-ditert-butylphenol. tert-butylphenol; 4,4′-dihydroxydiphenyl sulfone diethers, such as 4,4′-dimethoxydiphenyl sulfone, 4,4′-diethoxydiphenyl sulfone, 4,4′-dipropoxydiphenyl sulfone, 4,4′-diisopropoxydiphenyl sulfone, 4,4′-dibutoxydiphenyl sulfone, 4,4′-diisobutoxydiphenyl sulfone, 4,4′-dipentyloxydiphenyl sulfone, 4,4′-dihexyloxydiphenyl sulfone and 4,4′-diallyloxydiphenyl sulfone; 2,4'-dihydroxydiphenyl sulfone diethers, such as 2,4'-dimethoxydiphenyl sulfone, 2,4'-diethoxydiphenyl sulfone, 2,4'-dipropoxydiphenyl sulfone, 2,4'-diisopropoxydiphenyl sulfone, 2,4'-dibutoxydiphenyl sulfone, 2,4'-diisobutoxydiphenyl sulfone, 2,4'-dipentyloxydiphenyl sulfone, 2,4'-dihexyloxydiphenyl sulfone and 2,4'-diallyloxydiphenyl sulfone;1,2-bis(phenoxy)ethane, 1,2-bis(4-methylphenoxy)ethane, 1,2-bis(3-methyl-phenoxy)ethane, 1,2-bis(phenoxymethyl)benzene, 1,2-bis(4-methoxyphenylthio)ethane, 1,2-bis(4-methoxyphenoxy)propane, 1,3-phenoxy-2-propanol, 1,4-diphenylthio-2-butene, 1,4-diphenylthiobutane, 1,4-diphenoxy-2-butene, 1,5-bis(4-methoxyphenoxy)-3-oxapentane, 1,3-dibenzoyloxypropane, dibenzoyloxymethane , 4,4'-ethylenedioxy-bis-benzoic acid dibenzyl ester, bis[2-(4-methoxy-phenoxy)ethyl] ether, 2-naphthyl benzyl ether, 1,3-bis(2-vinyloxyethoxy)benzene, 1,4-diethoxy-naphthalene, 1,4-dibenzyloxynaphthalene, 1,4-dimethoxynaphthalene, 1,4-bis(2-vinyloxyethoxy)benzene, p-(2-vinyloxyethoxy)biphenyl, p-aryloxybiphenyl, p-propargyloxybiphenyl, p-benzyloxybenzene alcohol, 4-(m-methylphenoxymethyl)biphenyl, 4-methylphenyl-biphenyl ether, di-β-naphthylphenylenediamine, diphenyl amines, carbazole, 2,3-di-m-tolylbutane, 4-benzylbiphenyl, 4,4'-dimethylbiphenyl, terphenyls such as m-terphenyl and p-terphenyl; 1,2-bis(3,4-dimethylphenyl)ethane, 2,3,5,6-tetramethyl-4'-methyldiphenylmethane, 4-acetylbiphenyl, dibenzoylmethane, triphenylmethane, 1-hydroxynaphthoic acid phenyl ester, 1-hydroxy-2-naphthoic acid methyl ester, N-octadecylcarbamoyl-p-methoxycarbonylbenzene, p-benzyloxybenzoic acid benzyl ester, β-naphthoic acid phenyl ester, p-nitrobenzoic acid methyl ester, diphenyl sulfone, carbonic acid derivatives 1,1-diphenylpropanol, 1,1-diphenylethanol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene, benzyl p-benzyloxybenzoate, β-phenyl naphthoate, methyl p-nitrobenzoate, diphenyl sulfone, carbonic acid derivatives such as diphenyl carbonate, guaiacol carbonate, p-tolyl carbonate and phenyl α-naphthyl carbonate, 1,1-diphenylpropanol, 1,1-diphenylethanol, N-octadecylcarbamoylbenzene, dibenzyl disulfide, stearic acid, Amide AP-1 (7:3 mixture of stearamide and palmitamide), stearates such as aluminum stearate, calcium stearate and zinc stearate, etc.; and zinc palmitate, behenic acid, zinc behenate, montanic acid wax and polyolefin wax. ;

[0321] Illustrative examples thereof may include 2-naphthylbenzyl ether, m-terphenyl, 4-benzylbiphenyl, benzyl oxalate, di(4-chlorobenzyl) oxalate, a mixture of equal amounts of benzyl oxalate and di(4-chlorobenzyl) oxalate, di(4-methylbenzyl) oxalate, a mixture of equal amounts of di(4-chlorobenzyl) oxalate and di(4-methylbenzyl) oxalate, 1-hydroxy-2-naphthoic acid phenyl ester, 1,2-bis(phenoxy)ethane, 1,2-bis(3-methyl-phenoxy)ethane, 1,2-bis(phenoxymethyl)benzene, dimethyl terephthalate, stearamide, Amide AP-1 (a mixture of stearamide and palmitamide in a ratio of 7:3), diphenyl sulfone, and 4-acetylbiphenyl.

[0322] Specific illustrative examples thereof may include di(4-methylbenzyl oxalate), 1,2-bis(3-methyl-phenoxy)ethane, 1,2-bis(phenoxymethyl)benzene, diphenyl sulfone, and 2-naphthyl benzyl ether (benzyl-2-naphthyl ether).

[0323] Examples of fillers may include silicon dioxide, clay, kaolin, calcined kaolin, talc, satin white, aluminum hydroxide, calcium carbonate, magnesium carbonate, zinc oxide, titanium oxide, barium sulfate, magnesium silicate, aluminum silicate, plastic pigment, diatomaceous earth, talc and aluminum hydroxide. Among them, preferred examples thereof may include calcined kaolin and calcium carbonate. The proportion of the filler used is 0.1 to 15 parts by mass, preferably 1 to 10 parts by mass, relative to 1 part by mass of the color former. In addition, these fillers may be used in combination.

[0324] Examples of the dispersant may include: polyvinyl alcohols having various degrees of saponification and polymerization, such as polyvinyl alcohol, acetoacetylated polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, amide-modified polyvinyl alcohol, and butyral-modified vinyl alcohol; cellulose derivatives, such as methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, ethyl cellulose, acetyl cellulose, hydroxymethyl cellulose; sodium polyacrylate, polyacrylate, polyacrylamide, starch; sulfosuccinates (such as sodium dioctyl sulfosuccinate), sodium dodecylbenzenesulfonate, sodium salts of lauryl alcohol sulfonates, fatty acid salts, styrene-maleic anhydride copolymers, styrene-butadiene copolymers, polyvinyl chloride, polyvinyl acetate, polyacrylate, polyvinyl butyral, polyurethane, polystyrene and copolymers thereof, polyamide resins, silicone resins, petroleum resins, terpene resins, ketone resins, and coumarone resins.

[0325] The dispersant is used after being dissolved in a solvent such as water, alcohol, ketone, ester or hydrocarbon. Alternatively, the dispersant may be used in a state of being emulsified in water or other solvents or in the form of a paste dispersed therein.

[0326] Examples of the antioxidant may include 2,2′-methylenebis(4-methyl-6-tert-butylphenol), 2,2′-methylenebis(4-ethyl-6-tert-butylphenol), 4,4′-propylmethylenebis(3-methyl-6-tert-butylphenol), 4,4′-butylidenebis(3-methyl-6-tert-butylphenol), 4,4′-thiobis(2-tert-butyl-5-methylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,1,3-tris(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane, 4-{4-[1,1-bis(4-hydroxyphenyl)ethyl]-α,α-dimethylbenzyl}phenol, 1,1,3 -tris(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane, 2,2′-methylenebis(6-tert-butyl-4-methylphenol), 2,2′-methylenebis(6-tert-butyl-4-ethylphenol), 4,4′-thiobis(6-tert-butyl-3-methylphenol), 1,3,5-tris[{4-(1,1-dimethylethyl)-3-hydroxy-2,6-dimethylphenyl}methyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione and 1,3,5-tris[{3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl}methyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione.

[0327] Examples of the desensitizing agent may include aliphatic higher alcohols, polyethylene glycol, and guanidine derivatives.

[0328] Examples of the anti-sticking agent may include stearic acid, zinc stearate, calcium stearate, carnauba wax, paraffin wax, and ester wax.

[0329] Examples of the defoaming agent may include higher alcohols, fatty acid esters, oils, silicones, polyethers, modified hydrocarbons, and paraffin defoaming agents.

[0330] Examples of the light stabilizer may include: salicylic acid ultraviolet absorbers such as phenyl salicylate, p-tert-butylphenyl salicylate, and p-octylphenyl salicylate; benzophenone ultraviolet absorbers such as 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, and bis(2-methoxy-4-hydroxy-5-benzoylphenyl)methane;Benzotriazole ultraviolet absorbers such as 2-(2′-hydroxy-5′-methylphenyl)benzotriazole, 2-(2′-hydroxy-5′-tert-butylphenyl)benzotriazole, 2-(2′-hydroxy-3′, 5′-di-tert-butylphenyl)benzotriazole, 2-(2′-hydroxy-3′-tert-butyl-5′-methylphenyl)-5-chlorobenzotriazole, 2-(2′-hydroxy-3′, 5′-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2′-hydroxy-3′, 5′-di-tert-amylphenyl)benzotriazole, 2-(2′-hydroxy-5′-tert-butylphenyl)benzotriazole, 2-(2′-hydroxy-5′-(1″, 1″, 3″, 3″-tetramethylbutyl)phenyl)benzotriazole, 2-[2′-hydroxy-3′, 5′-di-tert-butylphenyl)-5-chlorobenzotriazole, '-(3',4',5',6'-tetrahydrophthalimidomethyl)-5'-methylphenyl]benzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2-[2'-hydroxy-3',5'-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, 2-(2'-hydroxy-3'-dodecyl-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3-undecyl-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tridecyl-5'-methylphenyl)benzotriazole, 2-(2-hydroxy-3'-tetradecyl-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3'-pentadecyl-5'-methylphenyl)benzotriazole oxadiazole, 2-(2′-hydroxy-3′-hexadecyl-5′-methylphenyl)benzotriazole, 2-[2′-hydroxy-4′-(2″-ethylhexyl)oxyphenyl]benzotriazole, 2-[2′-hydroxy-4′-(2″-ethylheptyl)oxyphenyl]benzotriazole, 2-[2′-hydroxy-4′-(2″-ethyloctyl)oxyphenyl]benzotriazole, 2-[2′-hydroxy-4′-(2″-propyloctyl)oxyphenyl]benzotriazole, 2-[2′-hydroxy-4′-(2″-propylheptyl)oxyphenyl]benzotriazole, 2-[2′-hydroxy-4′-(2″-propylhexyl)oxyphenyl]benzotriazole, 2-[2′-hydroxy-4′-(2″-propylhexyl)oxyphenyl]benzotriazole, 2-[2′-hydroxy-4′-(1″-ethylhexyl)oxyphenyl]benzotriazole, 2-[2′-hydroxy-4′-(1″-ethylheptyl)oxyphenyl]benzotriazole, 2-[2′-hydroxy-4′-(1′-ethyloctyl)oxyphenyl]benzotriazole, 2-[2′-hydroxy-4′-(1″-propyloctyl)oxyphenyl]benzotriazole, 2-[2′-hydroxy-4′-(1″-propylheptyl)oxyphenyl]benzotriazole, 2-[2′-hydroxy-4′-(1″-propylhexyl)oxyphenyl]benzotriazole, 2,2′-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)]phenol, and a condensation product of polyethylene glycol and methyl 3-[3-tert-butyl-5-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]propionate;Cyanoacrylate UV absorbers, hindered amine UV absorbers, such as bis(2,2,6,6-tetramethyl-4-piperidinyl sebacate), bis(2,2,6,6-tetramethyl-4-piperidinyl succinate) and bis(1,2,2,6,6-pentamethyl-4-piperidinyl 2-(3,5-di-tert-butyl)malonate); and 1,8-dihydroxy-2-acetyl-3-methyl-6-methoxynaphthalene. ;

[0331] Examples of the fluorescent whitening agent may include 4,4′-bis[2-anilino-4-bis(2-hydroxyethyl)amino-1,3,5-triazinyl-6-amino]stilbene-2,2′-disulfonic acid disodium salt, 4,4′-bis[2-anilino-4-bis(hydroxyethyl)amino-1,3,5-triazinyl-6-amino]stilbene-2,2′-disulfonic acid disodium salt, 4,4′-bis[2-anilino-4-bis(hydroxypropyl)amino-1,3,5-triazinyl-6-amino]stilbene-2,2′-disulfonic acid disodium salt, 4,4′-bis[2-methoxy-4-(2-hydroxyethyl)amino-1,3,5 -triazinyl-6-amino]stilbene-2,2'-disulfonic acid disodium salt, 4,4'-bis[2-methoxy-4-(2-hydroxypropyl)amino-1,3,5-triazinyl-6-amino]stilbene-2,2'-disulfonic acid disodium salt, 4,4'-bis[2-m-anilino-4-bis(hydroxyethyl)amino-1,3,5-triazinyl-6-amino]stilbene-2,2'-disulfonic acid disodium salt, 4-[2-p-sulfoanilino-4-bis(hydroxyethyl)amino-1,3,5-triazinyl-6-amino]-4'-[2-m-sulfoanilino-4-bis(hydroxyethyl)amino-1,3,5 -triazine-6-amino] stilbene-2,2'-disulfonic acid tetrasodium salt, 4,4'-bis[2-p-sulfoanilino-4-bis(hydroxyethyl)amino-1,3,5-triazine-6-amino] stilbene-2,2'-disulfonic acid tetrasodium salt, 4,4'-bis[2-(2,5-disulfoanilino)-4-phenoxyamino-1,3,5-triazine-6-amino] stilbene-2,2'-disulfonic acid hexasodium salt, 4,4'-bis[2-(2,5-disulfoanilino)-4-(p-methoxycarbonylphenoxy)amino-1,3,5-triazine-6-amino] stilbene-2,2'-disulfonic acid hexasodium salt, 4,4'-bis[2-(2,5-disulfoanilino)-4-formalinylamino-1,3,5-triazinyl-6-amino]stilbene-2,2'-disulfonic acid hexasodium salt, 4,4'-bis[2-(2,5-disulfoanilino)-4-formalinylamino-1,3,5-triazinyl-6-amino]stilbene-2,2'-disulfonic acid hexasodium salt ne-2,2′-disulfonic acid hexasodium salt) and 4,4′-bis[2-(2,5-disulfoaniline)-4-bis(hydroxyethyl)amino-1,3,5-triazinyl-6-amino]stilbene-2,2′-disulfonic acid hexasodium salt.

[0332] Method for producing heat-sensitive recording material

[0333] When the embodiments described herein are used for thermal recording paper, the paper can be produced in a conventional manner. For example, thermal recording paper can be produced by dispersing fine particles of the developer compound described herein and fine particles of the color former in an aqueous solution of a water-soluble binder such as polyvinyl alcohol or cellulose, respectively, mixing these suspension solutions, applying the mixture to a support such as paper, and drying it.

[0334] When the embodiments described herein are used for pressure-sensitive copy paper, the pressure-sensitive copy paper can be produced in the same manner as using a known developer or sensitizer. For example, a colorant microencapsulated by a method known in the art is dispersed in a suitable dispersant and applied to paper to prepare a colorant sheet. In addition, a dispersed solution of the developer is applied to paper to prepare a developer sheet. The two sheets prepared in this way are combined to prepare pressure-sensitive copy paper. The pressure-sensitive copy paper can be a unit consisting of: an upper layer of paper carrying microcapsules, the microcapsules containing a solution of the colorant in an organic solvent, wherein the microcapsules are applied to the lower side of the upper layer of paper; and a lower layer of paper carrying a developer (acidic substance), the upper surface of the lower layer of paper being applied with a developer. Alternatively, the pressure-sensitive copy paper can be a so-called self-contained paper which contains microcapsules and a developer applied to the same paper surface.

[0335] Conventionally known ones are used as developers used in production or developers used in combination with the compounds of the embodiments described herein. Examples thereof may include: inorganic acidic substances such as Japanese acid clay, activated clay, attapulgite, bentonite, colloidal silica, aluminum silicate, magnesium silicate, zinc silicate, tin silicate, calcined kaolin, and talc; aliphatic carboxylic acids such as oxalic acid, maleic acid, tartaric acid, citric acid, succinic acid, and stearic acid; aromatic carboxylic acids such as benzoic acid, p-tert-butylbenzoic acid, phthalic acid, gallic acid, salicylic acid, 3-isopropyl salicylic acid, 3-phenyl salicylic acid, 3-cyclohexyl salicylic acid, 3,5-di-tert-butylsalicylic acid, 3-methyl-5-benzylsalicylic acid, 3-phenyl-5-(2,2-dimethylbenzyl)salicylic acid, 3,5-di-(2-methylbenzyl)salicylic acid and 2-hydroxy-1-benzyl-3-naphthoic acid, and metal (e.g., zinc, magnesium, aluminum and titanium) salts of these aromatic carboxylic acids; phenol resin developers, such as p-phenylphenol-formaldehyde resin and p-butylphenol-acetylene resin, and mixtures of these phenol resin developers with aromatic metal salts.

[0336] Conventionally known paper, synthetic paper, film, plastic film, foamed plastic film, nonwoven fabric, recycled paper (eg recycled pulp), etc. can be used as the carrier according to the embodiment of the present invention. In addition, a combination thereof can also be used as the carrier.

[0337] If paper is used as a support, a dispersion solution containing a dispersion solution of a color former, a dispersion solution of a developer, and a dispersion solution of a filler may be directly applied to the paper, or the dispersion solution may be applied after applying a dispersion solution for an undercoat layer to paper and drying it. Preferably, the dispersion solution for an undercoat layer is applied before applying the dispersion solution, because better color development sensitivity can be obtained.

[0338] The dispersion solution for the undercoat layer is used to improve the smoothness of the support surface and is not particularly limited, but preferably contains a filler, a dispersant and water, specifically, preferably calcined kaolin or calcium carbonate as the filler, and preferably polyvinyl alcohol as the dispersant.

[0339] Examples of the method for forming the recording material layer on the support include a method comprising applying a dispersion solution containing a dispersion solution of a color former, a dispersion solution of a developer, and a dispersion solution of a filler to the support and then drying, a method comprising spraying such a dispersion solution on the support with a sprayer or the like and then drying, and a method comprising immersing the support in such a dispersion solution for a given time and then drying. In addition, examples of the application method include hand coating, a size press coater method, a roll coater method, an air knife coater method, a blend coater method, a flow coater method, a curtain coater method, a comma roll direct method, a gravure direct method, a gravure reverse method, and a reverse roll coater method.

[0340] Coating method

[0341] In one exemplary method, the heat-sensitive recording layer coating composition is applied at a concentration of about 1 to about 10 g / m 2 , such as from about 3 to about 7 g / m 2 The heat-sensitive recording layer coating composition can be applied to the support by a known coating device such as a coating bar, a roll coater, an air knife coater, a blade coater, a gravure coater, a die coater or a curtain coater.

[0342] If desired, an undercoat layer may also be provided between the carrier and the thermosensitive recording layer to improve the thermosensitivity and efficiency during recording. The undercoat layer may be formed by coating the carrier with an undercoat coating composition comprising organic hollow particles and / or an oil-absorbing pigment and a binder as a main component and then drying the coating. Representative examples of oil-absorbing pigments include kaolin, calcined kaolin, amorphous silica, precipitated calcium carbonate, and talc. The average pigment diameter may be from about 0.01 to about 5 μm, such as from about 0.02 to about 3 μm.

[0343] Representative examples of organic hollow particles include particles having a shell made of an acrylic resin, a styrene-based resin, and a vinylidene chloride-based resin and having a porosity of about 50 to about 99%. In an exemplary embodiment, the outer diameter of the organic hollow particles may be about 0.5 to about 10 μm, such as about 1 to about 5 μm. Exemplary organic hollow particles may be expandable hollow particles. A typical example of such expandable hollow particles is a microcapsule having an average diameter of about 0.1 to about 5 μm and including a vinylidene chloride resin shell and butane gas as a filling material. When a carrier coated with a primer layer containing such expandable hollow particles is subjected to heat treatment, the microcapsules expand to an average particle diameter of about 1 to about 30 μm. In an embodiment in which an oil-absorbing pigment is used in combination with organic hollow particles, the total amount of the two components may be about 40 to about 90% by weight, for example, about 50 to about 80% by weight, based on the primer layer.

[0344] An exemplary binder for the undercoat layer may be selected from the binder to be used for the thermosensitive recording layer. In particular, the exemplary binder is styrene-butadiene latex, polyvinyl alcohol or starch-vinyl acetate copolymer. Based on the undercoat layer, the exemplary amount of the binder is from about 5 to about 30% by weight, for example, from about 10 to about 20% by weight. In an exemplary embodiment, the undercoat recording layer coating composition is applied at about 2 to about 20 g / m 2 , such as about 4 to about 12 g / m 2 The amount (by dry weight) is applied to the carrier.

[0345] If necessary, a protective layer may be provided on the thermosensitive recording layer to enhance the resistance of the recorded image to water and chemicals (e.g., oil, fat, alcohol, plasticizer, etc.), thereby improving operability during recording. Generally, the protective layer may be formed by coating the thermosensitive recording layer with a protective layer coating composition comprising, as a main component, a binder having film-forming ability and optionally a pigment and / or an insolubiliser and / or a lubricant, and then drying the resulting coating film.

[0346] Representative examples of binders for use in the protective layer coating composition include polyvinyl alcohol (completely or partially hydrolyzed), carboxyl-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, silicone-modified polyvinyl alcohol, starch, gelatin, casein, gum arabic, cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose and acetyl cellulose, starch vinyl acetate graft copolymers, styrene-maleic anhydride copolymers, methyl vinyl ether-maleic anhydride copolymers, isopropylene-maleic anhydride copolymers and the like water-soluble resins, styrene-butadiene latex, acrylic latex, polyurethane latex and the like water-dispersible resins and mixtures thereof.

[0347] The protective layer coating composition may further include a pigment, a water resistance agent, a lubricant and, if necessary, other auxiliary agents selected from those used for the above-mentioned heat-sensitive recording layer coating composition.

[0348] In an exemplary embodiment, the protective layer coating composition may be about 0.5 to about 10 g / m 2 , such as about 1 to 5 g / m 2 The coating is applied in an amount of 100% by dry weight and can be applied with a coating apparatus similar to that used for coating the heat-sensitive layer.

[0349] A protective layer, an adhesive layer, and a magnetic layer may also be provided on the back side of the support.

[0350] The following non-limiting examples illustrate further aspects of the embodiments described herein.

[0351] There are several methods for printing coated thermal papers: by heat (thermal printers) or by light (laser).

[0352] For example, the coated thermal paper can be printed by laser marking or printing, such as by CO2 (IR radiation with a wavelength in the range of 780 to 1'000'000 nm). In an exemplary embodiment, in the laser marking / printing process, the energy is IR radiation generated by a CO2 laser or a Nd:YAG laser. For example, the energy can be IR radiation generated by a Co2 laser with a wavelength of 10600 nm.

[0353] Typically, the exact power and line speed of the IR laser are determined by the application and selected to be sufficient to produce the image, for example, when the wavelength of the IR laser is 10600nm and the diameter of the laser beam is 0.35mm, the power is typically 0.5 to 4W and the marking speed is typically 300 to 1500mm / s.

[0354] By using a photothermal activator FLDA-LED type. Example

[0355] Example 1 corresponds to the PERGAFAST 425 powder-material synthesis.

[0356] Example 1a: Synthesis of 5-sulfonyl chloride-isophthaloyl dichloride

[0357] To a mixture of 42 g (150 mmol) of 5-sulfoisophthalic acid sodium salt (95%, Sigma-Aldrich Inc.) and 160 ml (2200 mmol) of thionyl chloride (>99% GC, Fluka) is added 10 ml of N,N-dimethylformamide under stirring. The suspension is slowly heated to reflux and kept under reflux conditions for two hours, during which time the formation of HCl and SO2 indicates that the reaction proceeds. After the gas formation has ceased, the reaction mixture is cooled to room temperature. The yellowish suspension obtained is slowly poured onto 1000 g of ice cubes under stirring, during which time a slightly pinkish product precipitates. After stirring for 30 minutes at below 5°C, the precipitate is filtered. The wet filter cake thus obtained is deep frozen and freeze-dried to avoid premature hydrolysis.

[0358] Yield: 45.5 g of slightly yellowish powder. NMR (d6-DMSO): 9.15 (1H), 9.04 (2H).

[0359] Example 1b: 5-(N-3-Methylphenyl-sulfonylamino)-(N′,N″-bis-(3-methylphenyl)-isophthalic acid-diamide (toluene).

[0360] 1.5 g (5 mmol) of 5-sulfonyl chloride-isophthaloyl dichloride (synthesized as in Example 1a) was dispersed in 20 ml of toluene at room temperature. 3.3 g (30.9 mmol) of 3-methyl-aniline was slowly added to the white dispersion. Another 60 ml of toluene was added to the crude suspension, which was then heated to 100 ° C and stirred for 18 hours. After cooling to room temperature, the precipitate was filtered and washed with 30 ml of toluene, followed by the addition of 50 ml of demineralized water and 30 ml of HCl (10%). The compound was dried under reduced pressure (200 mbar) and 40 ° C.

[0361] Yield: 2g reddish product

[0362] Recrystallization

[0363] 10 g of crude 5-(N-3-methylphenyl-sulfonylamino)-(N′, N″-bis-(3-methylphenyl)-isophthalic acid diamide obtained in Example 1b were dissolved in 350 ml of methanol under reflux conditions to give a clear solution. 35 ml of water were added, after which some slight turbidity could be observed. The mixture was slowly cooled to room temperature over the course of 2 hours. The white precipitated needles were filtered off, washed with 50 ml of demineralized water and dried under reduced pressure (200 mbar) at 50° C.

[0364] Yield: 52%.

[0365] Melting point (DSC, 4°C / min): 195.3°C, 215.2°C, (different crystal forms).

[0366] NMR(d6-DMSO): 2.20(3H), 2.32(6H), 6.85(1H), 6.92(1H), 6.96(3H), 7.1 1(1H), 7.26(2H), 7.58(4H), 8.46(2H), 8.73(1H), 10.45(1H), 10.53(2H).

[0367] Example 1c: α-Form Directed Synthesis of 5-(N-3-methylphenyl-sulfonylamino)-(N′,N″-bis-(3-methylphenyl)-isophthalic acid-diamide

[0368] 110 ml (0.99 mol) of m-toluidine was added dropwise to a mixture of 49.0 g (0.16 mol) of 5-sulfonyl chloride-isophthaloyl dichloride (synthesized as in Example 1a) and 500 ml of toluene at 22° C. in 30 minutes. Then, another 500 ml of toluene was added again. The obtained product mixture was heated to 100° C. Then 1500 ml of toluene was added and the reaction mixture was kept at 100° C. for 3 hours. Afterwards, the reaction mixture was cooled to 22° C. The formed precipitate was filtered out. The obtained filter cake was suspended in 250 ml of water under stirring. The suspension was heated to 80° C. for 30 minutes. The water layer was removed by decantation at 80° C. Then 200 ml of 10% by weight of hydrochloric acid was added to the residue and the mixture was stirred at 40° C. for 30 minutes. Then, the water layer was decanted again. Thereafter, 800 ml of n-heptane was added to the residue and stirred at 22° C. for 30 minutes. The precipitate was collected by filtration and dried at 60°C under reduced pressure of a vacuum pump.

[0369] Yield: 81 g (96%), white solid, melting point 211.2° C. (DSC).

[0370] Example 1d: β-Type Directed Synthesis of 5-(N-3-methylphenyl-sulfonylamino)-(N′,N″-bis-(3-methylphenyl)-isophthalic acid-diamide

[0371] To a mixture of 10.8 g (0.1 mol) of m-toluidine in 50 ml of tetrahydrofuran was added a solution of 5.0 g (0.0166 mol) of 5-sulfonyl chloride-isophthaloyl dichloride (synthesized as in Example 1a) in 15 ml of tetrahydrofuran under stirring within 15 minutes. The reaction mixture was then heated to 65° C. for 5 hours. The formed precipitate was removed by filtration. The filtrate was dried under reduced pressure of a vacuum pump. The obtained residue was placed in 25 ml of tetrahydrofuran. The obtained solution was then poured into a mixture of 100 ml of methanol / water (9:1) and heated to 50° C. for 1 hour. Thereafter, the reaction mixture was cooled to 22° C. The obtained solid was collected by filtration and washed with methanol. The product was then dried at 60° C. under reduced pressure for 7 hours.

[0372] Yield: 5.0 g (58%), white solid, melting point 192.2° C. (DSC).

[0373] Example 1e: γ-Form Directed Synthesis of 5-(N-3-methylphenyl-sulfonylamino)-(N′,N″-bis-(3-methylphenyl)-isophthalic acid-diamide

[0374] 5 g (0.0166 mol) of 5-sulfonyl chloride-isophthaloyl dichloride (synthesized as in Example 1a) in 20 ml of toluene are added dropwise to a mixture of 10.8 g (0.1 mol) of m-toluidine in 75 ml of n-heptane at 75° C. over 45 minutes. The reaction mixture is then heated to 90° C. for 5 hours and then cooled to 60° C. Subsequently, 50 ml of water and 5 ml of concentrated hydrochloric acid are added at this temperature, followed by stirring at 60° C. for a further 15 minutes. Thereafter, the solid phase obtained is filtered off at this temperature. Thereafter, the filter cake obtained is first washed with 50 ml of water, then with 50 ml of n-heptane, and then dried on a suction filter by using a vacuum pump to draw air through the filter for 1 hour. The filter cake thus dried is suspended in 90 ml of a methanol / water mixture (9:1), and the suspension is stirred at 60° C. for 2 hours. After the suspension is cooled to 20° C., the resulting precipitate is filtered off and washed with 50 ml of a methanol / water mixture (1:1). Thereafter, the product was dried at 60° C. under reduced pressure of a vacuum pump for 7 hours.

[0375] Yield: 7.0 g (white solid), 82%, melting point 215.6° C., measured by DSC.

[0376] Example 1f: One-step method for synthesizing 5-(N-3-methylphenyl-sulfonylamino)-(N',N"-bis-(3-methylphenyl)-isophthalic acid diamide

[0377] Step 1: Synthesis of 5-sulfonyl chloride-isophthaloyl dichloride

[0378] A suspension of 150 ml (2.1 mol) thionyl chloride and 125 g (0.47 mol) 5-sulfoisophthalic acid sodium salt was heated to 70° C. At this temperature, a solution of 3.4 g (0.05 mol) N,N-dimethylformamide in 100 ml thionyl chloride was added via a dropping funnel over 1.5 hours. The reaction mixture was stirred at 70-75° C. for 2.5 hours until gas evolution ceased. The formation of crude acyl chloride was monitored by LC. After the reaction was complete, excess thionyl chloride was removed by distillation. Acid chlorides in the form of a colloidal substance and fine sodium chloride crystals were obtained. The substance was filtered and the filtrate was collected. 350 ml of toluene was added to the filtrate to obtain 450-500 g 5-sulfonyl chloride isophthaloyl dichloride solution.

[0379] Step 2: Convert 5-sulfonyl chloride-isophthaloyl dichloride to the corresponding acid tris-amide

[0380] A solution of 3 g Surfynol 104PG 50 (50% propylene glycol solution, Evonik) and 27 g (0.33 mol) sodium bicarbonate in 300 ml water was stirred at 20°C. 35 g (0.33 mmol) of m-toluidine was added at one time. The solution was heated to 30-40°C. 100 g (about 0.1 mol) of the intermediate solution prepared in step 1 was added over 1.5 hours. The reaction suspension formed was heated to 50-55°C and maintained at this temperature for 2 hours under stirring. The reaction was monitored by LC. When the conversion was complete, the reaction mixture was cooled to 20°C. The precipitate formed was collected by filtration at a suction filter. The obtained crude wet cake was washed with about 210 ml of water, then washed with 210 ml of toluene, and then dried in vacuo at 50°C for 12 hours.

[0381] Yield: 45 g (86%), white solid, bulk density 550 kg / m 3 .

[0382] The Bragg angles (2θ / CuKα) of the X-ray powder pattern of this material are: 5.4±0.2, 6.1±0.2, 6.3±0.2, 11.9±0.2, 12.6±0.2, 15.9±0.2, 16.6±0.2, 16.9±0.2, 18.1±0.2, 19.1±0.2, 19.7±0.2, 20.3±0.2, 22.0±0.2, 22.5±0.2, 23.1±0.2, 24.1±0.2, 24.9±0.2, 25.4±0.2, 26.3±0.2, and 27.7±0.2.

[0383] Example 2: Second non-phenolic developer NKK-1304 is prepared according to the synthesis method disclosed in EP 2923851 and / or via the synthesis of the intermediate 1-(2-aminophenyl) 3-phenylurea prepared by the reaction of o-phenylenediamine with phenyl isocyanate according to the literature (CJ Perry, Synthetic Commun. 38 (19) 3354 (2008)) and further reacted similarly to the procedure given in the literature (P. Singh et al., J. Mater. Chemistry C, 3, 5524 (2015)) to obtain NKK-1304. The final product and compound are represented by the following formula (I):

[0384]

[0385] In a particular embodiment, a chromogenic agent referred to herein as NKK-1304 is used and corresponds to the above general formula (I), wherein R1, R2 and R3 are all hydrogen atoms.

[0386]

[0387] Example 3: The second non-phenolic developer PERGAFAST 201 used in the following evaluations is a commercial grade developer from SOLENIS having the following structure:

[0388]

[0389] Grinding of color developer:

[0390] Preparation of developer dispersion A (solution A)

[0391] In a bead mill, 11 g of 5-(N-3-methylphenyl-sulfonylamino)-(N′,N″-bis-(3-methylphenyl)-isophthalic acid diamide, 0.2 g of surfactant 2,4,7,9-tetramethyl-5-decyne-4,7-diol ( 104, from Evonik), 8.9 g of Gohsenx as a dispersing aid TM A developer dispersion A was obtained by grinding a mixture of an aqueous solution (10%) of L-3266 (sulfonated polyvinyl alcohol, Nippon Gohsei) and a binder and 20 g of demineralized water to a median particle size of 1.0 μm.

[0392] In a similar manner, the following developer dispersions were prepared for comparison:

[0393] Dispersion Compound Dispersion B = Solution B 1-[2-(Benzenesulfonylamino)-phenyl]-3-phenylurea(NKK-1304) Dispersion C = Solution C 4-Methylbenzenesulfonic acid [3-(p-toluenesulfonylaminoformylamino)phenyl ester] (PF-201)

[0394] Preparation of Coupler Dispersion D (Solution D)

[0395] 15 g of 3-dibutylamino-6-methyl-7-anilinofluoran (Pergascript Black 2C, BASF SE), 30 g of 10% by weight polyvinyl alcohol ( 40-88, polyvinyl alcohol, Mw about 205.000 g / mol, Sigma-Aldrich Inc. / Kuraray Europe GmbH) solution, 0.3 g surfactant 2,4,7,9-tetramethyl-5-decyne-4,7-diol ( 104, from Evonik) and 15 g of water were ground to an average particle size of 1.0 μm to obtain dispersion D.

[0396] Preparation of sensitizer dispersion E (solution E)

[0397] 11.3 g of benzyl-2-naphthyl ether (Pergaspeed 305, BASF SE), 2.3 g of a 5% dispersant (sodium salt of a condensation product of naphthalenesulfonic acid and formaldehyde, NN 9401 from BASF SE), 5.7 g 10% by weight of polyvinyl alcohol ( An aqueous solution of 40-88 (polyvinyl alcohol, Mw of about 205,000, Sigma-Aldrich Inc. / Kuraray Europe GmbH) and 20.8 g of water were ground to an average particle size of 1.0 μm to obtain Dispersion E.

[0398] Preparation of filler dispersion F (solution F)

[0399] 15.8 g of precipitated calcium carbonate (Socal P3, from Solvay), 0.4 g of an aqueous dispersant solution (sodium polyacrylate ( A mixture of AA 4140 from BASF SE (Elastomer®, pH 7.5, active ingredient content 40% by weight) and 23.8 g of water was ground to an average particle size of 1.0 μm to give Dispersion F.

[0400] Heat-sensitive pigmented liquids and coating preparations:

[0401] Application Example C1: Preparation of a Thermosensitive Recording Layer Coating Composition

[0402] 15 g of dispersion A, 6.5 g of dispersion D, 11.5 g of dispersion E, 16 g of dispersion F, 19 g of 10% by weight polyvinyl alcohol ( 28-99, polyvinyl alcohol, Kuraray Europe GmbH) aqueous solution, 3g 17% zinc stearate ( F115 from Chukyo Europe) aqueous dispersion, 1.5 g of a 25% fatty amide emulsion (Hymicron L-271 from Chukyo Europe) and 58 g of distilled water were mixed and stirred to obtain a heat-sensitive recording layer coating composition.

[0403] The calcined kaolin ( 93, from BASF SE, coating weight 7g / m 2 ) to achieve a dry color former coating weight of 0.5 g / m 2 The coated heat-sensitive sheet was stored at 40° C. for 24 hours. The obtained heat-sensitive recording layer coating composition was calendered twice at 25 kN to obtain a smooth surface.

[0404] Application Example C2: Preparation of a Thermosensitive Recording Layer Coating Composition

[0405] 12 g of dispersion A, 3 g of dispersion B, 6.5 g of dispersion D, 11.5 g of dispersion E, 16 g of dispersion F, 19 g of 10% by weight polyvinyl alcohol ( 28-99, polyvinyl alcohol, Kuraray Europe GmbH) aqueous solution, 3g 17% zinc stearate ( F115, from Chukyo Europe) aqueous dispersion, 1.5 g of a 25% fatty amide emulsion (Hymicron L-271, from Chukyo Europe) and 58 g of distilled water were mixed and stirred to obtain a heat-sensitive recording layer coating composition.

[0406] The calcined kaolin ( 93 from BASF SE, coating weight 7 g / m 2 ) to achieve a dry color former coating weight of 0.5 g / m 2 The coated heat-sensitive sheet was stored at 40° C. for 24 hours. The obtained heat-sensitive recording layer coating composition was calendered twice at 25 kN to obtain a smooth surface.

[0407] Example C2 was applied repeatedly with different components to produce additional heat-sensitive recording layer coating compositions from C2 to C6.

[0408] Table A summarizes the different combinations and compositions used.

[0409] Application Example C7: Preparation of a Thermosensitive Recording Layer Coating Composition

[0410] 15 g of dispersion B, 6.5 g of dispersion D, 11.5 g of dispersion E, 16 g of dispersion F, 19 g of 10% by weight polyvinyl alcohol ( 28-99, polyvinyl alcohol, Kuraray Europe GmbH) aqueous solution, 3g 17% zinc stearate ( F115 from Chukyo Europe) aqueous dispersion, 1.5 g of a 25% fatty amide emulsion (Hymicron L-271 from Chukyo Europe) and 58 g of distilled water were mixed and stirred to obtain a heat-sensitive recording layer coating composition.

[0411] The calcined kaolin ( 93 from BASF SE, coating weight 7 g / m 2 ) to achieve a dry color former coating weight of 0.5 g / m 2 The coated heat-sensitive sheet was stored at 40° C. for 24 hours. The obtained heat-sensitive recording layer coating composition was calendered twice at 25 kN to obtain a smooth surface.

[0412] Table A

[0413]

[0414] Application Example C8: Preparation of a Thermosensitive Recording Layer Coating Composition

[0415] 15 g of dispersion A, 6.5 g of dispersion D, 11.5 g of dispersion E, 16 g of dispersion F, 19 g of 10% by weight polyvinyl alcohol ( 28-99, polyvinyl alcohol, Kuraray Europe GmbH) aqueous solution, 3g 17% zinc stearate ( F115 from Chukyo Europe) aqueous dispersion, 1.5 g of a 25% fatty amide emulsion (Hymicron L-271 from Chukyo Europe) and 43 g of distilled water were mixed and stirred to obtain a heat-sensitive recording layer coating composition.

[0416] The calcined kaolin ( 93 from BASF SE, coating weight 7 g / m 2 ) to achieve a dry color former coating weight of 0.25 g / m 2The coated heat-sensitive sheet was stored at 40° C. for 24 hours. The obtained heat-sensitive recording layer coating composition was calendered twice at 25 kN to obtain a smooth surface.

[0417] Application Example C9: Preparation of a Thermosensitive Recording Layer Coating Composition

[0418] 12 g of dispersion A, 3 g of dispersion C, 6.5 g of dispersion D, 11.5 g of dispersion E, 16 g of dispersion F, 19 g of 10% by weight polyvinyl alcohol ( 28-99, polyvinyl alcohol, Kuraray Europe GmbH) aqueous solution, 3g 17% zinc stearate ( F115, from Chukyo Europe) aqueous dispersion, 1.5 g of a 25% fatty amide emulsion (Hymicron L-271, from Chukyo Europe) and 43 g of distilled water were mixed and stirred to obtain a heat-sensitive recording layer coating composition.

[0419] The calcined kaolin ( 93 from BASF SE, coating weight 7 g / m 2 ) to achieve a dry color former coating weight of 0.25 g / m 2 The coated heat-sensitive sheet was stored at 40° C. for 24 hours. The obtained heat-sensitive recording layer coating composition was calendered twice at 25 kN to obtain a smooth surface.

[0420] Example C9 was repeated with different components to produce additional heat-sensitive recording layer coating compositions C9 to C13.

[0421] Table B summarizes the different combinations and compositions used.

[0422] Application Example C14: Preparation of a Thermosensitive Recording Layer Coating Composition

[0423] 15 g of dispersion C, 6.5 g of dispersion D, 11.5 g of dispersion E, 16 g of dispersion F, 19 g of 10% by weight polyvinyl alcohol ( 28-99, polyvinyl alcohol, Kuraray Europe GmbH) aqueous solution, 3g 17% zinc stearate ( F115, from Chukyo Europe) aqueous dispersion, 1.5 g of a 25% fatty amide emulsion (Hymicron L-271, from Chukyo Europe) and 43 g of distilled water were mixed and stirred to obtain a heat-sensitive recording layer coating composition.

[0424] The calcined kaolin ( 93 from BASF SE, coating weight 7 g / m 2 ) to achieve a dry color former coating weight of 0.25 g / m 2 The coated heat-sensitive sheet was stored at 40° C. for 24 hours. The obtained heat-sensitive recording layer coating composition was calendered twice at 25 kN to obtain a smooth surface.

[0425] Table B

[0426]

[0427] Evaluation of thermal recording materials

[0428] Dynamic sensitivity:

[0429] Thermosensitive recording materials prepared according to embodiments herein were evaluated as described below, and the results of the evaluation are summarized in Table C.

[0430] The evaluation involves printing the thermosensitive image pattern with a certain progressive energy condition per surface unit and under dynamic conditions, which means that a certain printing speed is adopted, preferably a speed in the range of 100 to 300 mm / s.

[0431] In the present embodiment, the thermal printing tester used was Atlantek Model 400 (manufactured by Atlantek Inc.), and each thermosensitive recording material was printed by simulating a speed of 100 mm / s and using a progressive printing energy as shown below for each pattern:

[0432] 3.217-4.623-6.065-7.489-8.876-10.318-11.742-13.166-14.571-15.995mJ / mm 2 .

[0433] The printed pattern thus obtained will be TM The optical density (black filter) [OD] was measured by Eyeone pro densitometer for evaluation.

[0434] Under fixed energy and speed conditions, higher OD means higher dynamic image sensitivity.

[0435] Table C

[0436]

[0437] Image and background stability:

[0438] The optical density (OD) of the thermally printed image and the background whiteness of the non-thermally printed areas of the media were measured before and after exposure to the weathering test.

[0439] The smaller the difference in optical density (OD) between the initial level and the level after aging, the higher the stability of the thermosensitive medium.

[0440] Image Optical Density (OD)

[0441] A thermal tester (Atlantek Model 400, manufactured by Atlantek Inc.) was used at 16 mJ / mm 2 Each heat-sensitive recording material was printed at 100 mm / s with an applied energy of 100 mm / s and printed using X-Rite / GretagMacbeth TM The density of the recorded image thus obtained was measured with an Eyeonepro densitometer.

[0442] background

[0443] The optical density (OD) of the unrecorded surface of the coated substrate was measured with an Eye One densitometer from X-Rite / Gretag-Macbeth.

[0444] Water resistance:

[0445] After thermal printing, the coated substrate was immersed in deionized water at 20°C for 24 hours. After this treatment, the sample was kept at room temperature during the time required for complete drying. The optical density (OD) of the image and background was then measured using an Eye One densitometer from X-Rite / Gretag-Macbeth.

[0446] The image sticking ratio is evaluated according to the following calculation method:

[0447] Residual ratio (%)=(OD after water resistance test) / (OD of untreated material)×100.

[0448] Front plasticizer resistance:

[0449] After thermal printing, at 40°C at 50 g / cm 2 The "front side" of the coated substrate, bearing the printed image, was placed in close contact with a sheet of PVC packaging film (containing a phthalate plasticizer) from Global Plastics Co., at a pressure of 100° for 24 hours.

[0450] After this treatment, the PVC film was removed from the front side and the samples were kept at room temperature for 1 hour.

[0451] The optical density (OD) of the image and background was then measured using an Eye One densitometer from X-Rite / Gretag-Macbeth within 8 hours after removal of the PVC film.

[0452] The image sticking ratio is evaluated according to the following calculation method:

[0453] Residual ratio (%)=(OD after front plasticizer resistance test) / (OD of untreated material)×100.

[0454] Oil resistance:

[0455] After thermal printing, 0.05 ml of cottonseed oil was evenly applied to the front side of the coated substrate, and the sample was kept at 40°C for 24 hours.

[0456] After this treatment, the OD of the image and background was measured using an Eye One densitometer from X-Rite / Gretag-Macbeth.

[0457] The image sticking ratio is evaluated according to the following calculation method:

[0458] Residual ratio (%)=(OD after oil resistance test) / (OD of untreated material)×100.

[0459] Heat resistance:

[0460] After thermal printing, the coated substrate was placed in a drying oven at 90° C. for 1 hour. After this treatment, the sample was kept at room temperature for 1 hour. Subsequently, the optical density (OD) of the image and background was measured using an Eye One densitometer from X-Rite / Gretag-Macbeth.

[0461] The image sticking ratio is evaluated according to the following calculation method:

[0462] Residual ratio (%)=(OD after heat resistance test) / (OD of untreated material)×100.

[0463] Image and background stability results for the tested thermal papers

[0464] Table D

[0465]

[0466] Table E

[0467]

[0468] Although at least one exemplary embodiment has been presented in the foregoing detailed description, it should be understood that there are a large number of variations. It should also be understood that one or more exemplary embodiments described herein are not intended to limit the scope, applicability or construction of the claimed subject matter in any way. On the contrary, the foregoing detailed description will provide a convenient roadmap for implementing one or more of the described embodiments to those skilled in the art. It should be understood that, without departing from the scope defined in the claims, various changes may be made to the function and arrangement of the elements, including equivalents and foreseeable equivalents known at the time of filing this patent application.

Claims

1. A thermosensitive recording material comprising a) color-forming compounds; b) a first non-phenolic developer of formula (I) wherein R and R1 are each independently hydrogen or C1-C 18 -alkyl; or a group of formula (II) wherein R2, R3, R4, R5, R6 are each independently hydrogen or C1-C8-alkyl, and wherein Q represents a direct bond or a C1-C8-alkylene group which may be branched or unbranched, and wherein when the C1-C8-alkylene group comprises more than two carbon atoms, the C1-C8-alkylene group comprises a main chain containing one or more oxygen atoms between two carbon atoms, and c) a second non-phenolic developer, wherein the second non-phenolic developer is a compound selected from the group consisting of: (i) A compound represented by the following formula (NI): in: R1, R2 and R3 each independently represent a hydrogen atom, a C1-C6 alkyl group or a C1-C6 alkoxy group; n1 and n3 each independently represent an arbitrary integer from 1 to 5; and n2 represents any integer from 1 to 4; (ii) A compound represented by the following formula (N-II): in: R1, R2 and R3 each independently represent a hydrogen atom, a C1-C6 alkyl group or a C1-C6 alkoxy group; n2 represents any integer from 1 to 4; n3 represents any integer from 1 to 5; and n4 represents any integer from 1 to 7; and (iii) a compound represented by the following formula (N-III): in R1, R2 and R3 each independently represent a hydrogen atom, a C1-C6 alkyl group or a C1-C6 alkoxy group; n2 represents any integer from 1 to 4; n3 represents any integer from 1 to 5; and n4 represents any integer from 1 to 7.

2. The thermosensitive recording material according to claim 1, wherein the formula (NI) is the following formula (N-IV): wherein R1 and R3 each independently represent a hydrogen atom, a C1-C6 alkyl group or a C1-C6 alkoxy group.

3. The thermosensitive recording material according to claim 1, wherein the formula (NI) is the following formula (NV): wherein R1 represents a hydrogen atom, a C1-C6 alkyl group or a C1-C6 alkoxy group.

4. The thermosensitive recording material according to claim 1, wherein the ratio of the first non-phenolic developer to the second non-phenolic developer of the thermosensitive recording material is 10:90 to 90:10 in terms of dry proportion of each non-phenolic developer.

5. The thermosensitive recording material according to claim 1, wherein the ratio of the first non-phenolic developer to the second non-phenolic developer of the thermosensitive recording material is 20:80 to 60:40 in terms of dry proportion of each non-phenolic developer.

6. The heat-sensitive recording material according to claim 1, further comprising at least one sensitizer selected from the group consisting of benzyl 2-naphthyl ether, stearic acid amide, hydroxymethyl stearic acid amide, p-benzyl biphenyl, m-terphenyl, 2-benzyloxynaphthalene, 4-methoxybiphenyl, dibenzyl oxalate, di(4-methylbenzyl oxalate), di(4-chlorobenzyl oxalate), dimethyl phthalate, dibenzyl terephthalate, dibenzyl isophthalate, 1,2-diphenoxyethane, 1,2-bis(4-methylphenoxy)ethane, 1,2-bis(3-methyl-phenoxy)ethane, 4, 4'-dimethylbiphenyl, 1-hydroxy-2-naphthoic acid phenyl ester, 4-methylphenylbiphenyl ether, 1,2-bis(3,4-dimethylphenyl)ethane, 2,3,5,6-4'-methyldiphenylmethane, 1,4-diethoxy-naphthalene, 1,4-diacetoxybenzene, 1,4-dipropoxybenzene, o-xylylene-bis(phenyl ether), 4-(m-methylphenoxymethyl)biphenyl, p-hydroxyacetanilide, p-hydroxybutyric acid anilide, p-hydroxynonanoic acid anilide, p-hydroxylauric acid anilide, p-hydroxyoctadecanoic acid anilide, N-phenyl-benzenesulfonamide and sensitizers of the following formula wherein R and R' are the same as or different from each other and each represents a C1-C6 alkyl group.

7. A recording sheet comprising: vector, and A recording composition layer on a support, wherein the recording composition comprises the heat-sensitive recording material according to any one of claims 1 to 6.

8. A method of forming an image, the method comprising: Providing a thermosensitive recording material according to any one of claims 1 to 6; and The image is recorded by a heat-sensitive recording material.

9. The method of claim 8, wherein recording the image comprises performing a thermal printing process or a laser marking / printing process selected from a CO2, Nd:YAG or FLDA-LED type process by using a photothermal activator.

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