Thermosensitive recording medium and image recording method

Abstract

A thermosensitive recording medium is provided that includes: a support; a thermosensitive recording layer arranged in a partial region of a top surface of the support; a color ink layer arranged in a partial region of the top surface of the support; a first protective part arranged in at least a partial region of at least a top surface of the color ink layer; and a second protective part arranged on at least a top surface of the thermosensitive recording layer.

Description

[DESCRIPTION][Title of Invention]THERMOSENSITIVE RECORDING MEDIUM AND IMAGE RECORDING METHOD[Technical Field]

[0001] The present disclosure relates to a thermosensitive recording medium and an image recording method.[Background Art]

[0002] Conventionally, there is a widely known thermosensitive recording medium including a thermosensitive recording layer utilizing a color-developing reaction of an electron-donating compound and an electron-accepting compound on a support including paper and synthetic paper. The conventional thermosensitive recording medium is prepared by applying and subsequently drying a thermosensitive recording layer forming liquid in which an electrondonating compound and an electron-accepting compound are blended with a resin such as polyvinyl alcohol, a pigment such as calcium carbonate, and a dispersant such as a surfactant, and the resulting blend is dispersed into fine particles, over the entire surface of the support by an application method such as an air-knife coater, a bar coater, a blade coater, a curtain coater, or gravure printing.

[0003] Such conventional thermosensitive recording medium has a problem in that applying the thermosensitive recording layer forming liquid over the entire surface of the support leads to waste of the thermosensitive recording layer forming liquid applied on non-printed portions, hence increased costs and environmental impact. Another problem is that if a thermosensitive recording medium with a transparent support is used as a packaging material for various types of containers such as PET bottles, when the thermosensitive recording layer is formed over the entire surface of the support, it is difficult to see the contents inside the packaging. In heat-sealing the thermosensitive recording medium to be packaged in a container or the like, there is a problem that if the thermosensitive recording layer is formed over the entire surface of the support, color development may occur due to the heat in the heat-sealing process.

[0004] Accordingly, a thermosensitive recording medium has been proposed which, for example, when the thermosensitive recording layer forming liquid is applied on a partial region of the support that requires printing, attempts to reduce the amount of the thermosensitive recording layer forming liquid in non-printed portions, and thus, to reduce costs and an environmental impact. Further, such a thermosensitive recording medium, when a transparent support is used, attempts to visually check the inside of a packaging material through a region on the support without the thermosensitive recording layer, and to reduce color development due to the heat during heat-sealing (see PTL 1).

[0005] An example of a technology for providing the thermosensitive recording layer on a partial region of the support includes a thermosensitive film in which a thermosensitive layer is partially provided on at least one surface of a substrate, and a protective layer is covered over the entire surface of the thermosensitive layer (see PTL 2). The proposed thermosensitive film attempts to prevent wear of a thermal head protective layer caused by contact with the thermosensitive film during printing.

[0006] An example of a technology attempting to improve the abrasion resistance of a printed material by a protective layer includes overprinting an ultraviolet (UV)-curable transparent varnish on a printing ink (see PTL 3).[Citation List][Patent Literature][PTL 1]Japanese Unexamined Patent Application Publication No. 2022-151636[PTL 2]Japanese Unexamined Patent Application Publication No. 2021-45972[PTL 3]Japanese Unexamined Patent Application Publication No. 2002-309142[Summary of Invention][Technical Problem]

[0007] An object of the present disclosure is to provide a thermosensitive recording medium which improves the abrasion resistance of a color ink layer against a thermal head, and also prevents printing defect caused by accumulation of ink residue on the thermal head due to abrasion of the color ink layer.[Solution to Problem]

[0008] Embodiments of the present invention provide a thermosensitive recording medium that includes: a support; a thermosensitive recording layer arranged in a partial region of a top surface of the support; a color ink layer arranged in a partial region of the top surface of the support; a first protective part arranged in at least a partial region of at least a top surface of the color ink layer; and a second protective part arranged on at least a top surface of the thermosensitive recording layer.[Advantageous Effects of Invention]

[0009] According to embodiments of the present disclosure, a thermosensitive recording medium is provided which improves the abrasion resistance of a color ink layer against a thermal head, and also prevents printing defect caused by accumulation of ink residue on the thermal head due to abrasion of the color ink layer.[Brief Description of Drawings]

[0010] A more complete appreciation of embodiments of the present disclosure and many of the attendant advantages and features thereof can be readily obtained and understood from the following detailed description with reference to the accompanying drawings.FIG. 1 A is a schematic top view of a thermosensitive recording medium according to a first embodiment.FIG. IB is a schematic cross-sectional view taken along line IB-IB of FIG. 1 A.FIG. 2A is a schematic top view of a thermosensitive recording medium according to a second embodiment.FIG. 2B is a schematic cross-sectional view taken along line IIB-IIB of FIG. 2A.FIG. 3 A is a schematic top view of a thermosensitive recording medium according to a third embodiment.FIG. 3B is a schematic cross-sectional view taken along line IIIB-IIIB of FIG. 3 A.FIG. 4A is a schematic top view of a thermosensitive recording medium according to a fourth embodiment.FIG. 4B is a schematic cross-sectional view taken along line IVB-IVB in FIG. 4A.FIG. 5 A is a schematic top view of a thermosensitive recording medium according to a fifth embodiment.FIG. 5B is a schematic cross-sectional view taken along line VB-VB in FIG. 5A.FIG. 6A is a schematic top view of a thermosensitive recording medium according to a sixth embodiment.FIG. 6B is a schematic cross-sectional view taken along line VIB-VIB in FIG. 6A.FIG. 7A is a schematic top view of a thermosensitive recording medium according to a seventh embodiment.FIG. 7B is a schematic cross-sectional view taken along line VIIB-VIIB in FIG. 7A.FIG. 8A is a schematic top view of a thermosensitive recording medium according to an eighth embodiment.FIG. 8B is a schematic cross-sectional view taken along line VIIIB-VIIIB in FIG. 8A.FIG. 9A is a schematic top view of a thermosensitive recording medium according to a ninth embodiment.FIG. 9B is a schematic cross-sectional view taken along line IXB-IXB in FIG. 9A.FIG. 10A is a schematic top view of a thermosensitive recording medium according to a tenth embodiment.FIG. 10B is a schematic cross-sectional view taken along line XB-XB in FIG. 10A.FIG. 11 A is a schematic top view of a thermosensitive recording medium according to an eleventh embodiment.FIG. 1 IB is a schematic cross-sectional view taken along line XIB-XIB in FIG. 11 A.FIG. 12A is a schematic top view of a thermosensitive recording medium according to a twelfth embodiment.FIG. 12B is a schematic cross-sectional view taken along line XIIB-XIIB of FIG. 12A.FIG. 13 A is a schematic top view of a thermosensitive recording medium according to a thirteenth embodiment.FIG. 13B is a schematic cross-sectional view taken along line XIIIB-XIIIB in FIG. 13 A. FIG. 14A is a schematic top view of a thermosensitive recording medium according to Comparative Example 1.FIG. 14B is a schematic cross-sectional view taken along line XIVB-XIVB in FIG. 14A. The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. Also, identical or similar reference numerals designate identical or similar components throughout the several views.[Description of Embodiments]

[0011] In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that have a similar function, operate in a similar manner, and achieve a similar result.Referring now to the drawings, embodiments of the present disclosure are described below. As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.(Thermosensitive Recording Medium)A thermosensitive recording medium according to the present disclosure includes a support, a thermosensitive recording layer arranged in a partial region of a top surface of the support, a color ink layer arranged in a partial region of the top surface of the support, a first protective part arranged in at least a partial region of at least a top surface of the color ink layer, and a second protective part arranged on at least the top surface of the thermosensitive recording layer. The thermosensitive recording medium according to the present disclosure may further optionally include other members.

[0012] It is noted that the present disclosure is not limited to the embodiments described below, and may be changed within the scope conceivable by a person skilled in the art, including other embodiments, additions, modifications, omissions, or the like. The resultant embodiments are included within the scope of the present disclosure, as long as the operations and effects of the present disclosure are achieved in any aspect.

[0013] Conventional thermosensitive recording media have a problem that a thermosensitive recording layer and a color ink layer are each provided in a partial region of the support where printing is required. Compared to printing the color ink layer over the entire surface of the support (that is, 100% of the total area of a surface of the support on which the color ink layer is formed), the edge of the color ink layer provided on the same side as the thermosensitiverecording layer comes into contact with a thermal head, and thus, a significant damage is caused in the color ink layer due to abrasion, which results in a loss of the design expressed by the color ink layer. Additionally, a released color ink layer accumulates on the thermal head, and thus, heat is blocked from the thermal head, causing problems such as printing defects of the thermosensitive recording layer and scratches on the support surface due to ink residue.

[0014] By contrast, the thermosensitive recording medium according to the present disclosure includes a first protective part arranged in at least a partial region of at least the top surface of the color ink layer, and a second protective part arranged on at least the top surface of the thermosensitive recording layer, and thus, the abrasion resistance of the color ink layer against the thermal head can be improved and printing defects caused by accumulation of ink residue on the thermal head due to abrasion of the color ink layer can be prevented.

[0015] The sizes, the materials, the shapes, the relative arrangements, and the like of the components described in the embodiments are merely illustrative examples and are not intended to limit the scope of the present disclosure unless otherwise specified. It is noted that the sizes and the positional relationships of components illustrated in each drawing may be exaggerated for clarity of explanation. In the following description, the same names and symbols indicate the same or similar components, and detailed descriptions will be omitted as appropriate. To avoid overly complicated drawings, schematic diagrams with some omitted elements may be used, and end views illustrating only the cut surface may be employed for cross-sectional views.

[0016] In the present disclosure, polygons such as rectangles, triangles, and quadrilaterals are referred to as polygons, including shapes in which the corners of the polygons are for example, rounded, chamfered, de-angled, or rounded. Shapes in which processing is applied not only to the corners (ends of the sides) but also to the middle portions of the sides are also referred to as polygons. That is, a shape partially processed while still retaining a polygonal shape as its base is intended to be included in the interpretation of "polygon" described in this disclosure.

[0017] The same is true not only of polygons, but also of words expressing specific shapes such as trapezoids, circles, and irregular shapes. The same is true in dealing with each side included in the shape. That is, even when the comers or middle part of a certain side are processed, a "side" includes the processed parts in interpreting the "side". In distinguishing a "polygon" or a "side" without any partially processed parts from a processed shape, the word "strict" will be added to express a quadrangle without any partially processed parts, for example, as a "strict quadrangle".

[0018] In the following description, terms indicating specific directions or positions (for example, "upper", "lower", "side", "top surface", "lower surface", "side surface", "X", "Y", "Z", and other terms incorporating such terms) will be used optionally. However, the use of such terms is for the purpose of facilitating understanding of the invention with reference to the drawings, and the meanings of such terms should not be construed as excessively limiting the technical scope of the present disclosure. For example, when the term "top surface" is used, it does not necessarily mean that the invention must always be used facing upwards. In the embodiments, "cover" is not limited to direct contact, but also includes indirect covering, for example, through another member.

[0019] The shape of the thermosensitive recording medium according to the present disclosure is not particularly limited and may be appropriately selected depending on the purpose. Examples of the shape include a label form, a sheet form, and a roll form.

[0020] <Support>The support supports the thermosensitive recording layer and the color ink layer, and further optionally supports other members.

[0021] The shape of the support is not particularly limited and can be appropriately selected depending on the purpose. Examples of the shape include, but are not limited to, polygonal shapes such as a square and a rectangle, a circle, an ellipse, a flat plate, and a sheet form.

[0022] The structure of the support is not particularly limited and can be appropriately selected depending on the purpose. Such a structure may be a single-layer structure or a laminated structure having two or more layers formed of two or more materials.

[0023] The structure of the support is not particularly limited and can be appropriately selected depending on the purpose. Such a structure may be a single-layer structure or a multi-layer structure having two or more layers.

[0024] The size of the support is not particularly limited and can be appropriately selected depending on the size of the desired thermosensitive recording medium.

[0025] The material of the support is not particularly limited and can be appropriately selected depending on the purpose. Examples of the material include, but are not limited to, paper, synthetic paper, and plastic film.

[0026] The plastic film is not particularly limited and can be appropriately selected depending on the purpose. Examples of the plastic film include, but are not limited to, films formed of polyester resins such as polyethylene terephthalate (PET), polycarbonate, polystyrene (PS),polymethyl methacrylate (PMMA), polyethylene (PE), polypropylene (PP), and polyvinyl chloride. Such plastic films may be used alone or in combination of two or more types.

[0027] Among such plastic films, from the viewpoint of flexibility, polyethylene terephthalate (PET) or polypropylene (PP) is preferred as the support, and biaxially oriented polyethylene terephthalate (PET) is preferred from the viewpoint of excellent strength, heat resistance, dimensional stability, and the like.

[0028] Examples of the support having a multi-layer structure having two or more layers include, but are not limited to, a laminate of cellulose fiber and synthetic paper, and a laminate of cellulose fiber and a plastic film or a laminate of a plastic film and synthetic paper.

[0029] The support may be surface-modified by a corona discharge treatment, an oxidation reaction treatment (for example, chromic acid), an etching treatment, an adhesion enhancing treatment, an antistatic treatment, or the like, for the purpose of improving adhesion to the thermosensitive recording layer, the color ink layer, the first protective part, the second protective part, and the like.

[0030] The support may be a white opaque film formed by adding additives such as a white raw material and a filler to the above-mentioned material, or a foamed sheet.

[0031] The support may further contain inorganic materials, organic compounds, and the like, from the viewpoint of improving heat resistance, mechanical strength, and the like.

[0032] The inorganic material contained in the support is not particularly limited and can be appropriately selected depending on the purpose. Examples of the inorganic material include, but are not limited to, glass, quartz, and inorganic single crystals. Such inorganic materials may be used alone or in combination of two or more types.

[0033] The organic compound contained in the support is not particularly limited and can be appropriately selected depending on the purpose. Examples of the organic compound include, but are not limited to, benzotriazole-based compounds, triazine-based compounds, benzophenone-based compounds, and hindered amine-based compounds. Such organic compounds may be used alone or in combination of two or more types.

[0034] It is preferable that the support is a transparent film because it can easily confirm the contents when the thermosensitive recording medium is used for a packaging material for foods and the like. As used herein, the support being "transparent" means that the haze (turbidity) measured in accordance with ASTM D1003 or ISO 14782 regarding film transparency is about 10% or less, but 5% or less is more preferable. The haze of the support may bemeasured using a haze meter (for example, device name: HZ-V3, manufactured by Suga Test Instruments Co., Ltd.).

[0035] The average thickness of the support is not particularly limited and can be appropriately selected depending on the purpose, but from the viewpoints of transparency and ease of processing, the average thickness is preferably 3 pm or more and 300 pm or less. When the average thickness of the support is 3 pm or more, the strength is high, and when the average thickness is 300 pm or less, the transparency is high and the stiffness is low, so that the processability is good.

[0036] As used herein, the "average thickness" of the support means an average value calculated from the thicknesses at 20 points selected at random in the support, after measuring the thicknesses at such 20 points in the support. The thickness of the support may be measured using a film thickness meter (for example, K-402B STAND and electronic micrometer K351C, manufactured by Anritsu Corporation).

[0037] <Thermosensitive Recording Layer>The thermosensitive recording layer is arranged in a partial region of the top surface of the support. The thermosensitive recording layer is preferably provided between the support and the second protective part, or between the color ink layer and the second protective part.

[0038] As used herein, when the thermosensitive recording layer is arranged on the "top surface" of the support, this means not only that the thermosensitive recording layer is laminated directly on one surface of the support, but also that the thermosensitive recording layer may be laminated on one surface of the support via another layer or member. For example, the thermosensitive recording layer may be arranged on the top surface of the color ink layer arranged on the support.

[0039] As used herein, the term "top surface of the support" is a term used to describe the laminated structure of the thermosensitive recording medium according to the present disclosure, and is not a term that means that the surface on which the thermosensitive recording layer is arranged is used facing upward in the usage mode of the thermosensitive recording medium.

[0040] As used herein, when the thermosensitive recording layer is arranged in a "partial region" of the top surface of the support, this means that the area of the thermosensitive recording layer is arranged to occupy less than 100% of the total area of the top surface of the support.

[0041] A shape, a structure, a size, the number, and arrangement of the thermosensitive recording layer are not particularly limited as long as the thermosensitive recording layer is arranged in the partial region on the top surface of the support, and can be appropriately selecteddepending on the purpose.

[0042] The thermosensitive recording layer contains an electron-donating compound and an electronaccepting compound, and further optionally contains other components.

[0043] «Electron-Donating Compound»The electron-donating compound is not particularly limited and can be appropriately selected according to the purpose from those typically used in thermosensitive recording media, and examples of the electron-donating compound include, but are not limited to, leuco compounds such as triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, and indolinophthalide-based dyes. Such electron-donating compounds may be used alone or in combination of two or more types.

[0044] Examples of black dye compounds include, but are not limited to, 6-(diethylamino)-2-[3-(trifluoromethyl)anilino]spiro[9H-xanthene-9,3'(rH)-isobenzofuran]-r-one, 2'-anilino-3'-methyl-6'-(dipentylamino)spiro[isobenzofuran-l(3H),9'-[9H]xanthene]-3-one, 2'-anilino-6'-dibutylamino-3'-methylspiro[phthalide-3, 9'-[9H]xanthene], 2'-anilino-6'-(N-ethyl-N-isopentylamino)-3'-methylspiro[phthalido-3,9'-[9H]xanthene], 2-(phenylamino)-3-methyl-6-[ethyl(p-tolyl)amino]spiro[9H-xanthene-9,l'(3'H)-isobenzofuran]-3'-one, 3-diethylamino-6-methyl-7-anilinofluoran, and 3-dibutylamino-6-methyl-7-anilinofluoran. Such black dye compounds may be used alone or in combination of two or more types.

[0045] Examples of red dye compounds include, but are not limited to, 6'-(di ethylamino)- 1', 2'-benzofluoran, 9-(N-ethyl-N-isopentylamino)spiro[benzo[a]xanthene-12, 3'-phthalide], 2'-methyl-6'-(N-p-tolyl-N-ethylamino)spiro[isobenzofuran-l(3H), 9'-[9H]xanthene]-3-one, 2'-chloro-6'-(diethylamino)spiro[isobenzofuran-l(3H), 9'-[9H]xanthene]-3-one, 6'-(dibutylamino)-2'-bromo-3'-methylspiro[phthalide-3,9'-xanthene], and 3,3-bis(l-n-butyl-2-methyl-3-indolyl)phthalide. Such red dye compounds may be used alone or in combination of two or more types.

[0046] Examples of blue dye compounds include, but are not limited to, 3-[4-(diethylamino)-2-hexyloxyphenyl]-3-(l-ethyl-2-methylindol-3-yl)-4-azaphthalide, 3-(4-diethylamino-2-ethoxyphenyl)-3-(l-ethyl-2-methylindol-3-yl)-4-azaphthalide, and 3', 6'-bis(diphenylamino)spiro[phthalide-3,9’-xanthene]. Such blue dye compounds may be used alone or in combination of two or more types.

[0047] Examples of green dye compounds include, but are not limited to, l-ethyl-8-[N-ethyl-N-(4-methylphenyl)amino]-2,2,4-trimethyl-l,2-dihydrospiro[HH-chromeno[2,3-g]quinoline-ll,3'-phthalide], 2'-(dibenzylamino)-6'-(diethylamino)fluoran, and 2'-(N-phenyl-N-methylamino)-6'-(N-p-tolyl-N-ethylamino)spiro[isobenzofuran-l(3H), 9’-[9H]xanthene]-3-one. Such greendye compounds may be used alone or in combination of two or more types.

[0048] Examples of yellow or orange dye compounds include, but are not limited to, F. Color Yellow- 17, Orange 100, and Orange-DCF. Such yellow or orange dye compounds may be used alone or in combination of two or more types.

[0049] The 50% cumulative volume particle size (D50) of the electron-donating compound is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.05 pm or more and 0.5 pm or less, and more preferably 0.1 pm or more and 0.3 pm or less. The 50% cumulative volume particle size (D50) of the electron-donating compound can be measured, for example, by using a laser diffraction / scattering type particle size distribution measuring device (for example, device name: LA-960, manufactured by Horiba, Ltd.).

[0050] The content of the electron-donating compound is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 5% by mass or more and 40% by mass or less, and more preferably 10% by mass or more and 30% by mass or less, based on the total mass of the thermosensitive recording layer.

[0051] «Electron-Accepting Compound»The electron-accepting compound is not particularly limited as long as the electron-accepting compound has electron-accepting properties allowing the electron-donating compound to react and develop color when heated, and can be appropriately selected according to the purpose from those typically used in thermosensitive recording media, but is preferably a color developer.

[0052] The color developer is not particularly limited and can be appropriately selected depending on the purpose. Examples of the color developer include, but are not limited to, phenolic substances, non-phenolic substances, organic or inorganic acidic substances, and esters or salts thereof.

[0053] Specific examples of the color developer include, but are not limited to, gallic acid, salicylic acid, 3-isopropylsalicylic acid, 3-cyclohexylsalicylic acid, 3,5-di-tert-butylsalicylic acid, 3,5-di-a-methylbenzylsalicylic acid, 4,4'-isopropylidenediphenol, l,l'-inopropylidenebis(2-chlorophenol), 4,4'-isopropylidenebis(2,6-dibromophenol), 4,4'-isopropylidenebis(2,6-dichlorophenol), 4, 4'-isopropylidenebis(2 -methylphenol), 4,4'-isopropylidenebis(2,6-dimethylphenol), 4,4'-isopropylidenebis(2-tert-butylphenol), 4,4'-sec-butylidenediphenol, 4,4'-cyclohexylidenebisphenol, 4, 4'-cyclohexylidenebis(2 -methylphenol), 4-tert-butylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, a-naphthol, P-naphthol, 3,5-xylenol, thymol, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, a novolak phenol resin, 2,2'-thiobis (4,6-dichlorophenol), catechol, resorcine, hydroquinone, pyrogallol, phloroglycine, phloroglycine carboxylic acid, 4-tert-octylcatechol, 2,2'-methylenebis (4-chlorophenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2, 2, -dihydroxydiphenyl, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, p-hydroxybenzoic acid-p-chlorobenzyl, p-hydroxybenzoic acid-o-chlorobenzyl, p-hydroxybenzoic acid-p-methylbenzyl, p-hydroxybenzoic acid-n-octyl, benzoic acid, zinc salicylate, 1 -hydroxyl-naphthoic acid, 2-hydroxy-6-naphthoic acid, zinc 2-hydroxy-6-naphthoate, 4-hydroxydiphenyl sulfone, 4-hydroxy-4'-chlorodiphenyl sulfone, bis(4-hydroxyphenyl)sulfide, 2-hydroxy-p-toluic acid, zinc 3,5-di-tert-butylsalicylate, tin 3,5-di-tert -butylsalicylate, tartaric acid, oxalic acid, maleic acid, citric acid, succinic acid, stearic acid, 4-hydroxyphthalic acid, boric acid, thiourea derivatives, 4-hydroxythiophenol derivatives, bis(4-hydroxyphenyl)acetic acid, ethyl bis(4-hydroxyphenyl)acetate, n-propyl bis(4-hydroxyphenyl)acetate, m-butyl bis(4-hydroxyphenyl)acetate, phenyl bis(4-hydroxyphenyl)acetate, benzyl bis(4-hydroxyphenyl)acetate, phenethyl bis(4-hydroxyphenyl)acetate, bis(3-methyl-4-hydroxyphenyl)acetic acid, bis(3-methyl-4-hydroxyphenyl)methyl acetate, bis(3-methyl-4-hydroxyphenyl)n-propyl acetate, l,7-bis(4-hydroxyphenylthio)3,5-dioxaheptane, l,5-bis(4-hydroxyphenylthio)3 -oxaheptane, dimethyl 4-hydroxyphthalate, 4-hydroxy-4'-methoxydiphenyl sulfone, 4-hydroxy-4'-ethoxydiphenyl sulfone, 4-hydroxy-4'-isopropoxy diphenyl sulfone, 4-hydroxy-4'-propoxydiphenyl sulfone, 4-hydroxy-4'-butoxydiphenyl sulfone, 4-hydroxy-4'-isobutoxydiphenyl sulfone, 4-hydroxy-4-butoxydiphenyl sulfone, 4-hydroxy-4'-tert-butoxydiphenyl sulfone, 4-hydroxy-4'-benzyloxydiphenyl sulfone, 4-hydroxy-4'-phenoxydiphenyl sulfone, 4-hydroxy-4'-(m-methylbenzyloxy)diphenyl sulfone, 4-hydroxy-4'-(p-methylbenzyloxy)diphenyl sulfone, 4-hydroxy-4'-(O-methylbenzyloxy)diphenyl sulfone, 4-hydroxy-4'-(p-chlorobenzyloxy)diphenyl sulfone, l,l-bis(4-hydroxyphenyl)-l -phenyl ethane, l,l-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1, 1, l-tris(4-hydroxyphenyl)ethane, N,N'-di-[3-(p-toluenesulfonyl)oxy]phenylurea, and [3-(3-phenylureido)phenyl]-4-methylbenzenesulfonate. Such color developers may be used alone or in combination of two or more types.

[0054] The 50% cumulative volume particle size (D50) of the electron-accepting compound is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.05 pm or more and 0.5 pm or less, and more preferably 0.1 pm or more and 0.3 pm or less. The 50% cumulative volume particle size (D50) of the electron-accepting compound can be measured, for example, by using a laser diffraction / scattering type particle size distribution measuring device (for example, device name: LA-960, manufactured by Horiba, Ltd.).

[0055] The content of the electron-accepting compound is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 5% by mass or more and 40% by mass or less, and more preferably 10% by mass or more and 30% by mass or less,based on the total mass of the thermosensitive recording layer.

[0056] The mass ratio between the content of the electron-donating compound and the content of the electron-accepting compound is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of transparency stability, however, the content of the electron-accepting compound is preferably 1 part by mass or more and 20 parts by mass or less, more preferably 1 part by mass or more and 10 parts by mass or less, and even more preferably 1 part by mass or more and 4 parts by mass or less, per 1 part by mass of the electron-donating compound.

[0057] The average thickness of the thermosensitive recording layer is not particularly limited and can be selected appropriately optionally, but is preferably 1 pm or more and 20 pm or less, and more preferably 2 pm or more and 10 pm or less.

[0058] As used herein, the "average thickness" of the thermosensitive recording layer means an average value calculated from the thicknesses at 20 points selected at random in the thermosensitive recording layer, after measuring the thicknesses at such 20 points in the thermosensitive recording layer.The thickness of the thermosensitive recording layer may be measured using a film thickness meter (for example, K-402B STAND and electronic micrometer K351C, manufactured by Anritsu Corporation). The thickness of the thermosensitive recording layer may be measured by cutting the thermosensitive recording medium in the thickness direction (lamination direction) using a cross-sectional sample preparation device (for example, Cross Section Polisher SM-09020CP, manufactured by JEOL Ltd.) to expose the cross-section surface, and observing the cross-section surface with a scanning electron microscope (SEM) (for example, S-3700, manufactured by Hitachi High-Tech Corporation).

[0059] «Other Components»Other components in the thermosensitive recording layer are not particularly limited and can be appropriately selected according to the purpose from those typically used in thermosensitive recording media, and examples thereof may include, but are not limited to, photothermal conversion materials, ultraviolet absorbing materials, binder resins, auxiliary additives, heat-fusible substances, lubricants, fillers, ultraviolet absorbing agents, antioxidants, sensitizers, and light stabilizers.

[0060] The contents of other components in the thermosensitive recording layer are not particularly limited and can be appropriately selected depending on the purpose.

[0061] - Photothermal Conversion Materials - The photothermal conversion materials are materials that absorb laser light and convert theabsorbed laser light into heat, and can be broadly divided into inorganic materials and organic materials.

[0062] —Inorganic Materials—Examples of the inorganic materials serving as the photothermal conversion materials include, but are not limited to, carbon black and particles of at least one of a metal boride and a metal oxide. Examples of metals contained in the metal boride and the metal oxide include, but are not limited to, Ge, Bi, In, Te, Se, and Cr. Among such metals, the inorganic materials serving as the photothermal conversion materials are preferably materials having high absorption of light in the near-infrared wavelength region and low absorption of light in the visible wavelength region, and metal borides and metal oxides are more preferred. Specific examples of the metal borides and the metal oxides suitably include at least one selected from the group consisting of hexaborides, tungsten oxide compounds, antimony tin oxide (ATO), indium tin oxide (ITO), and zinc antimonate.

[0063] Examples of hexaborides include, but are not limited to, LaBe, CeBe, PrBe, NdBe, GdBe, TbBe, DyBe, HoBe, YBe, SmBe, EuBe, ErBe, TmBe, YbBe, LuBe, SrBe, CaBe, and (La,Ce)Be.

[0064] Examples of the tungsten oxide compound include, but are not limited to, fine particles of tungsten oxide represented by general formula: WyOz (wherein W is tungsten, O is oxygen, and 2.2 < z / y < 2.999), or fine particles of a composite tungsten oxide represented by general formula: MxWyOz (wherein M is one or more elements selected from the group consisting of H, He, alkali metals, alkaline earth metals, rare earth elements, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and I, W is tungsten, O is oxygen, 0.001 < x / y < 1, and 2.2 < z / y < 3.0), as described in International Publication No. 2005 / 037932, Japanese Unexamined Patent Application Publication No. 2005-187323, and the like. Among such tungsten oxide compounds, as the tungsten oxide compound, cesium-containing tungsten oxide is particularly preferred because of high absorption in the near infrared region and low absorption in the visible region.

[0065] Among antimony tin oxide (ATO), indium tin oxide (ITO), and zinc antimonate, ITO is particularly preferable because of high absorption in the near infrared region and low absorption in the visible region.

[0066] These are formed in layers by vacuum deposition or by bonding particulate materials with a resin or the like.

[0067] —Organic materials—Various types of dyes can be employed appropriately for the organic material serving as thephotothermal conversion material depending on the wavelength of light to be absorbed.When a semiconductor laser is employed for the light source, a near-infrared absorbing dye having an absorption peak in the vicinity of 600 nm to 1,200 nm is used. Specifically, examples of the organic materials serving as the photothermal conversion materials include, but are not limited to, cyanine dyes, quinone dyes, quinoline derivatives of indonaphthol, phenylenediamine-based nickel complexes, and phthalocyanine-based dyes. Such organic materials may be used alone or in combination of two or more types.

[0068] Such photothermal conversion materials may be used alone or in combination of two or more types.

[0069] The content of the photothermal conversion material in the thermosensitive recording layer is not particularly limited and can be appropriately selected depending on the purpose, but it is preferably 0.1% by mass or more and 10% by mass or less, and more preferably 0.3% by mass or more and 5% by mass or less, based on the total mass of the thermosensitive recording layer.

[0070] The photothermal conversion material may be contained in the thermosensitive recording layer, or in a layer other than the thermosensitive recording layer. When the photothermal conversion material is contained in a layer other than the thermosensitive recording layer, it is preferable to provide a photothermal conversion layer adjacent to the thermosensitive recording layer.

[0071] - Ultraviolet Absorbing Materials - The ultraviolet absorbing materials are not particularly limited and can be appropriately selected depending on the purpose. Examples of the ultraviolet absorbing materials include, but are not limited to, salicylic acid-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, and benzotriazole-based ultraviolet absorbers.

[0072] Specific examples of the ultraviolet absorbing materials include, but are not limited to, phenyl salicylate, p-tert-butylphenyl salicylate, p-octylphenyl salicylate, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyl oxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, bis(2-methoxy-4-hydroxy-5-benzoylphenyl)methane, 2-(2'-hydroxy-5'-methylphenyljbenzotri azole, 2-(2'-hydroxy-5'-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di- tert-butylphenyljchlorobenzotri azole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotri azole, 2-(2'-hydroxy-3',5'-di-tert-amylphenyl)benzotriazole, 2-{2'-hydroxy-3'-(3",4",5",6"-tetrahydrophthalimidomethyl)-5'-methylphenyl}benzotriazole, 2,2'-methylenebis{4 -(1, l,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol}, 2-(2'-hydroxy-5'-methacryloxyphenyl)-2H-benzotriazole, 2-(3,5-di-t-amyl-2-hydroxyphenyl)benzotriazole, 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, and 2-(5-methyl-2-hydroxyphenyl)benzotriazole. Such ultraviolet absorbing materials may be used alone or in combination of two or more types.

[0073] - Binder Resins - The binder resins are not particularly limited and can be appropriately selected depending on the purpose. Examples of the binder resins include, but are not limited to, thermoplastic resins, thermosetting resins, and photocurable resins. The properties of such resins are not particularly limited, and examples of such resins include, but are not limited to, water-soluble resins, water-dispersible resins, and solvent-soluble resins.

[0074] Examples of the binder resins include, but are not limited to, acrylic resins, polyvinyl alcohol resins, starch or derivatives thereof; cellulose derivatives such as hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, and ethyl cellulose; water-soluble polymers such as sodium polyacrylate, polyvinylpyrrolidone, acrylamide-acrylic acid ester copolymers, styrene-acrylic copolymers, acrylamide-acrylic acid ester-methacrylic acid ternary copolymers, styrene-maleic anhydride copolymer alkali salts, isobutylene-maleic anhydride copolymer alkali salts, polyacrylamide, sodium alginate, gelatin, and casein; emulsions such as polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylic acid ester, vinyl chloride-vinyl acetate copolymers, polybutyl methacrylate, and ethylene-vinyl acetate copolymers; and latexes such as styrene-butadiene copolymers and styrene-butadiene-acrylic copolymers. Such binder resins may be used alone or in combination of two or more types. Among such binder resins, when transparency is required, acrylic resins, styrene-acrylic copolymers, and the like are preferred as the binder resin.

[0075] - Auxiliary Additives - Examples of the auxiliary additives include, but are not limited to, various types of hindered phenol compounds and hindered amine compounds which have electron accepting properties but relatively little color-developing ability.

[0076] Specific examples of the auxiliary additives include, but are not limited to, 2,2'-methylenebis(4-ethyl-6-tertiary butylphenol), 4,4'-butylidenebis(6-tertiary butyl-2-methylphenol), l,l,3-tris(2-methyl-4-hydroxy-5-tertiary butylphenyl)butane, 1, 1 ,3-tris(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane, 4,4'-thiobis(6-tertiary butyl-2-methylphenol), tetrabromobisphenol A, tetrabromobisphenol S, 4,4-thiobis(2-methylphenol), 4,4'-thiobis(2-chlorophenol), tetrakis(l,2,2,6,6-pentamethyl-4-piperidyl)-l,2,3,4-butane tetracarboxylate, and tetrakis(l,2,2,6,6-tetramethyl-4-piperidyl)-l,2,3,4-butane tetracarboxylate. Such auxiliary additives may be used alone or in combination of two or more types.

[0077] - Heat-Fusible Substances - Examples of the heat-fusible substances include, but are not limited to, fatty acids such as stearic acid and behenic acid; fatty acid amides such as stearic acid amide and palmitic acid amide; fatty acid metal salts such as zinc stearate, aluminum stearate, calcium stearate, zinc palmitate, and zinc behenate; p-benzylbiphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, P-benzyloxynaphthalene, P-phenyl naphthoate, phenyl 1 -hydroxy -2-naphthoate, methyl l-hydroxy-2-naphthoate, diphenyl carbonate, glycol carbonate, dibenzyl terephthalate, dimethyl terephthalate, 1,4-dimethoxynaphthalene, 1,4-di ethoxynaphthalene, 1,4-dibenzyloxynaphthalene, 1,2-diphenoxy ethane, l,2-bis(3-methylphenoxy)ethane, 1,2-bis(4-methylphenoxy)ethane, l,4-diphenoxy-2-butene, l,2-bis(4-methoxyphenylthio)ethane, dibenzoylmethane, 1,4-diphenylthiobutane, l,4-diphenylthio-2-butene, l,3-bis(2-vinyloxy ethoxy )benzene, 1 ,4-bis(2-vinyloxy ethoxy )benzene, p-(2-vinyloxy ethoxy )biphenyl, p-aryloxybiphenyl, p-propargyloxybiphenyl, dibenzoyloxymethane, dibenzoyloxypropane, dibenzyl disulfide, 1,1 -diphenylethanol, 1,1 -diphenylpropanol, p-benzyloxybenzyl alcohol, l,3-phenoxy-2-propanol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene, N-octadecyl carbamoylbenzene, l,2-bis(4-methoxyphenoxy)propane, l,5-bis(4-methoxyphenoxy)-3 -oxapentane, dibenzyl oxalate, bis(4-methylbenzyl) oxalate, and bis(4-chlorobenzyl) oxalate. Such heat-fusible substances may be used alone or in combination of two or more types.

[0078] - Lubricants - Examples of the lubricants include, but are not limited to, higher fatty acids or metal salts thereof, higher fatty acid amides, higher fatty acid esters, animal waxes, vegetable waxes, mineral waxes, and petroleum waxes. Such lubricants may be used alone or in combination of two or more types.

[0079] Examples of the animal waxes include, but are not limited to, a beeswax, lanolin, and spermaceti.

[0080] Examples of the vegetable waxes include, but are not limited to, a candelilla wax, a carnauba wax, a rice wax, a wood wax, and jojoba oil.

[0081] Examples of the mineral waxes include, but are not limited to, be ceresin or a derivative thereof.

[0082] Examples of the petroleum waxes include, but are not limited to, paraffin, petrolatum, a microcrystalline wax, and petrolatum.

[0083] An example of synthetic hydrocarbon waxes includes, but is not limited to, Fischer-Tropschwax.

[0084] Examples of hydrogenated waxes include, but are not limited to, hydrogenated castor oil and derivatives of hydrogenated castor oil.

[0085] - Fillers - Examples of the fillers include, but are not limited to, inorganic fine powders such as calcium carbonate, silica, zinc oxide, titanium oxide, zirconium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, kaolin, talc, surface-treated calcium, and surface-treated silica; and organic fine powders such as urea-formaldehyde resins, styrene-methacrylic acid copolymers, polystyrene resins, and vinylidene chloride resins. Such fillers may be used alone or in combination of two or more types.

[0086] The content of the filler in the thermosensitive recording layer is not particularly limited and can be appropriately selected depending on the purpose, but the content is preferably 0.4 parts by mass or less, and more preferably 0.2 parts by mass or less, per 1 part by mass of the binder resin.

[0087] <Color Ink Layer>The color ink layer is arranged in a partial region of the top surface of the support. That is, the color ink layer is arranged on the same side of the support as the thermosensitive recording layer. The color ink layer is preferably provided between the support and the first protective part, or between the support and the thermosensitive recording layer.

[0088] The color ink layer is a layer on which color ink is printed and has various colors, materials, and thicknesses. The color ink layer can impart design to the image recorded on the thermosensitive recording medium according to the present disclosure, and can form the background of the image printed on the thermosensitive recording layer. Therefore, in using the thermosensitive recording medium for packaging printing, when the color ink layer is provided, a product name, a manufacturer name, an ingredient list, and the like can be written before the product is packaged, and the product can also be given with excellent design. The thermosensitive recording medium according to the present disclosure is not limited to use for packaging, and the color ink layer may be printed with information such as characters, marks, pictures, bar codes, or two-dimensional codes such as QR codes (registered trademark).

[0089] In the thermosensitive recording medium according to the present disclosure, partial printing can be performed by arranging the color ink layer in a partial region of the top surface of the support, and thus, the color ink layer can be formed simultaneously with the thermosensitive recording layer. As the color ink layer is arranged in a partial region of the top surface of the support, when contents are packaged in the thermosensitive recording medium serving as apackaging sheet, the contents can be easily viewed from the region without the color ink layer.

[0090] As used herein, when the color ink layer is arranged on the "top surface" of the support, this means not only that the color ink layer is laminated directly on one surface of the support, but also that the color ink layer may be laminated on one surface of the support via another layer or member. The color ink layer is preferably laminated directly on one surface of the support.

[0091] As used herein, the term "top surface of the support" is a term used to describe the laminated structure of the thermosensitive recording medium according to the present disclosure, and is not a term that means that the surface on which the color ink layer is arranged is used facing upward in the usage mode of the thermosensitive recording medium. However, the color ink layer is arranged on the same side of the support as the thermosensitive recording layer.

[0092] As used herein, when the color ink layer is arranged in the "partial region" of the top surface of the support, this means that the color ink layer is arranged so that the area of the color ink layer is less than 100% of the total area of the top surface of the support.

[0093] A shape, a structure, a size, the number, and arrangement of the color ink layers are not particularly limited as long as the color ink layer is arranged in a partial region on the top surface of the support, and can be appropriately selected depending on the purpose.

[0094] The color ink layer contains a coloring material and a binder resin, and further optionally contains other components. The binder resin and the other components may be the same as those in the thermosensitive recording layer.

[0095] «Coloring Materials»The coloring material is not particularly limited and can be appropriately selected depending on the purpose, and known pigments or dyes can be used.

[0096] The content of the coloring material in the color ink layer is not particularly limited as long as the effects of the present disclosure are not impaired, and can be appropriately selected depending on the purpose.

[0097] The average thickness of the color ink layer is not particularly limited and can be selected appropriately optionally, but is preferably 0.05 pm or more and 4 pm or less, and more preferably 0.1 pm or more and 2 pm or less.

[0098] As used herein, the "average thickness" of the color ink layer means an average value calculated from the thicknesses at 20 points selected at random from the color ink layer, after measuring the thicknesses at such 20 points. The thickness of the color ink layer can bemeasured by cutting the thermosensitive recording medium in the thickness direction (lamination direction) using a cross-sectional sample preparation device (for example, Cross-Section Polisher SM-09020CP, manufactured by JEOL Ltd.) to expose the cross-section surface, and then observing the cross-section surface with a scanning electron microscope (SEM) (for example, S-3700, manufactured by Hitachi High-Tech Corporation).

[0099] <First Protective Part>The first protective part is arranged in at least a partial region of the top surface of the color ink layer. As the thermosensitive recording medium according to the present disclosure includes the first protective part, the thermosensitive recording medium can improve the abrasion resistance of the color ink layer against the thermal head and can also prevent printing defects caused by the accumulation of ink residue on the thermal head due to abrasion of the color ink layer.

[0100] As used herein, the "top surface" of the color ink layer means a surface of the color ink layer opposite to the surface on which the support is placed.

[0101] As used herein, the first protective part being "arranged on the top surface" of the color ink layer means not only that the first protective part is directly laminated on one surface of the color ink layer, but also that the first protective part may be laminated on one surface of the color ink layer via another layer or member.

[0102] The first protective part being arranged on "at least the top surface" of the color ink layer means that the first protective part may be arranged on a surface other than the top surface of the color ink layer, for example, on a side surface. When the first protective part is arranged on the side surface of the color ink layer, the first protective part arranged on the top surface of the color ink layer and the first protective part arranged on the side surface of the color ink layer may be arranged continuously or may not be arranged continuously.

[0103] For example, when the first protective part is laminated directly on the top surface of the color ink layer and arranged directly on the side surface of the color ink layer, the first protective part on the top surface of the color ink layer and the first protective part on the side surface of the color ink layer may be arranged continuously. When the first protective part is laminated on the top surface of the color ink layer via another layer or member and is arranged directly on the side surface of the color ink layer, the first protective part on the top surface of the color ink layer and the first protective part on the side surface of the color ink layer may not be arranged continuously.

[0104] As used herein, the first protective part being arranged in "at least a partial region" of at least the top surface of the color ink layer means that the first protective part may be arranged suchthat the area of the first protective part is less than 100% of the total area of the top surface of the color ink layer (that is, the first protective part may be arranged in a partial region of the top surface of the color ink layer), or may be arranged to be 100% (that is, the first protective part may be arranged over at least the entire upper surface of the color ink layer), or may be arranged to exceed 100% (that is, the first protective part may be arranged to extend beyond the top surface of the color ink layer). It is noted that it is preferable that the first protective part is not arranged beyond the top surface of the support. When the first protective part is arranged such that the area of the first protective part is less than 100% of the total area of the top surface of the color ink layer, it is preferred that another layer or member is arranged on the top surface of the color ink layer without the first protective part.

[0105] A shape, a structure, a size, the number, and arrangement of the first protective part are not particularly limited as long as the first protective part is arranged in at least a partial region of the top surface of the color ink layer, and can be appropriately selected depending on the purpose. The first protective part is preferably in the form of a layer.

[0106] The first protective part contains a binder resin, and preferably further contains a crosslinking agent, a pigment (filler), a wax, and the like, and may further optionally contain other components.

[0107] Conventional printing inks for thermosensitive recording media are formed of ultraviolet-curable resins and have high hardness. By contrast, it is preferable that the first protective part does not contain ultraviolet curable resins. This is because the ultraviolet curable resins are not suitable for printing inks for food containers due to the risk of migration of low molecular components.

[0108] - Binder Resins - The binder resins are not particularly limited and can be appropriately selected depending on the purpose. Examples of the binder resins include, but are not limited to, thermoplastic resins, thermosetting resins, and photocurable resins. The properties of such resins are not particularly limited, and examples of such resins include, but are not limited to, water-soluble resins, water-dispersible resins, and solvent-soluble resins.

[0109] The binder resins contained in the first protective part can be those similar to the binder resins described in the section titled as "- Binder Resins -" under "«Other Components»" in the above section titled as "<Thermosensitive Recording Layer>".

[0110] The content of the binder resins in the first protective part is not particularly limited as long as the effects of the present disclosure are not impaired, and can be appropriately selected depending on the purpose.

[0111] - Crosslinking Agent - The crosslinking agent is not particularly limited and can be appropriately selected depending on the purpose, but it is preferable that the crosslinking agent allows for reduction of the solubility of the water-soluble resin in water by reacting with the water-soluble resin.

[0112] Specific examples of the crosslinking agent include, but are not limited to, glyoxal derivatives, methylol derivatives, epichlorohydrin, polyamide epichlorohydrin, epoxy compounds, aziridine compounds, hydrazine, hydrazide derivatives, oxazoline derivatives, and carbodiimide derivatives. Such crosslinking agents may be used alone or in combination of two or more types. Among such crosslinking agents, polyamide epichlorohydrin is preferred as the crosslinking agent because the polyamide epichlorohydrin is highly safe to be handled and the curing time required to impart water resistance is short.

[0113] The content of the crosslinking agent in the first protective part is not particularly limited as long as the effects of the present disclosure are not impaired, and can be appropriately selected depending on the purpose. However, the content is preferably 10 parts by mass or more and 60 parts by mass or less, and more preferably 20 parts by mass or more and 50 parts by mass or less, relative to 100 parts by mass of the binder resin.

[0114] - Pigments - It is preferable that the first protective part contains the pigment in terms of improving the transportability in a thermal printer.

[0115] The pigment (filler) is not particularly limited and can be appropriately selected depending on the purpose. The pigment (filler) may be an inorganic filler or an organic filler.

[0116] Examples of the inorganic filler include, but are not limited to, carbonates, silicates, metal oxides, and sulfate compounds.

[0117] Specific examples of the inorganic filler include, but are not limited to, zinc oxide, calcium carbonate, barium sulfate, titanium oxide, lithopone, talc, rosewood, kaolin, aluminum hydroxide, and calcined kaolin.

[0118] Examples of the organic filler include, but are not limited to, silicone resins, cellulose, epoxy resins, nylon resins, phenol resins, polyurethane resins, urea resins, melamine resins, polyester resins, polycarbonate resins, styrene resins, acrylic resins, polyethylene resins, formaldehyde resins, polymethyl methacrylate resins, crosslinked polystyrene resins, urea resins, crosslinked polymethyl methacrylate resins, and melamine-formaldehyde resins.

[0119] Such pigments (fillers) may be used alone or in combination of two or more types.

[0120] The content of the pigment in the first protective part is not particularly limited as long as the effects of the present disclosure are not impaired, and can be appropriately selected depending on the purpose. However, the content is preferably 10 parts by mass or more and 200 parts by mass or less, and more preferably 30 parts by mass or more and 100 parts by mass or less, relative to 100 parts by mass of the binder resin.

[0121] - Wax - It is preferable for the first protective part to contain a wax in terms of improving the slipperiness with respect to the thermal head.

[0122] The wax is not particularly limited and can be appropriately selected depending on the purpose. Examples of the wax include, but are not limited to, an oxidized polyethylene wax, a montan wax, zinc stearate, and a silicone wax. Such waxes may be used alone or in combination of two or more types. Among such waxes, oxidized polyethylene wax is preferred.

[0123] Examples of the oxidized polyethylene wax include, but are not limited to, a polyethylene wax oxidized by air oxidation and / or ozone oxidation (introducing a carboxyl group, a hydroxyl group and / or a formyl group).

[0124] The weight average molecular weight of the oxidized polyethylene wax is not particularly limited and may be appropriately selected depending on the purpose, but is preferably 500 or more and 10,000 or less, more preferably 600 or more and 9,000 or less, and particularly preferably 700 or more and 8,000 or less. The weight average molecular weight of the oxidized polyethylene wax can be measured using a static light scattering photometer (for example, the product name: SLS-6000, static light scattering photometer, manufactured by Otsuka Electronics Co., Ltd.) at a measurement temperature of 160°C by using 1-chloronaphthalene as a solvent.

[0125] Commercially available oxidized polyethylene waxes include, but are not limited to, the product name: RP-960 (manufactured by Chukyo Yushi Co., Ltd., solid content: 30%) and the product name: L-787 (manufactured by Chukyo Yushi Co., Ltd., solid content: 30%).

[0126] The volume average particle size of the wax is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.3 pm or more and 6 pm or less. The volume average particle size of the wax can be measured using a laser diffraction / scattering type particle size distribution measuring device (for example, trade name: LA-960, manufactured by Horiba, Ltd.).

[0127] The content of the wax in the first protective part is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 100 parts by mass or less, and more preferably 25 parts by mass or less, per 100 parts by mass of the binder resin.

[0128] The wax in the first protective part may be optionally used in combination with other known lubricants. In the first protective part, examples of other lubricants that can be combined with the wax include the waxes described in the lubricants as other components in the thermosensitive recording layer.

[0129] - Other Components - The other components in the first protective part are not particularly limited as long as the effects of the present disclosure are not impaired and can be appropriately selected depending on the purpose. Examples of the other components include, but are not limited to, auxiliary additive components such as a surfactant, a heat-fusible substance, a lubricant, and an agent for preventing color development due to pressure. Components similar to the other components in the thermosensitive recording layer may be used.

[0130] The contents of the other components in the first protective part are not particularly limited as long as the effects of the present disclosure are not impaired, and can be appropriately selected depending on the purpose.

[0131] The average thickness of the first protective part is not particularly limited and can be selected at random as necessary, but is preferably 0.5 pm or more and 5 pm or less, and more preferably 1 pm or more and 3 pm or less.

[0132] As used herein, the "average thickness" of the first protective part layer means an average value calculated from the thicknesses at 20 points selected at random from the first protective part, after measuring the thicknesses at such 20 points.The thickness of the first protective part can be measured by using a cross-sectional sample preparation device (for example, a cross-section polisher SM-09020CP, manufactured by JEOL Ltd.) to cut the thermosensitive recording medium in the thickness direction (lamination direction) to expose the cross-section surface, and then observing the crosssection surface with a scanning electron microscope (SEM) (for example, S-3700, manufactured by Hitachi High-Tech Corporation).

[0133] < Second Protective Part>The second protective part is arranged on at least the top surface of the thermosensitive recording layer. When the thermosensitive recording medium according to the present disclosure includes the second protective part, the abrasion resistance of the thermosensitiverecording layer against a thermal head can be improved.

[0134] As used herein, the "top surface" of the thermosensitive recording layer means a surface of the thermosensitive recording layer opposite to the surface on which the support is placed.

[0135] As used herein, the second protective part being "arranged on the top surface" of the thermosensitive recording layer means not only that the second protective part is directly laminated on one surface of the thermosensitive recording layer, but also that the second protective part may be laminated on one surface of the thermosensitive recording layer via another layer or member. For example, the first protective part may be arranged on at least the top surface of the thermosensitive recording layer, and the second protective part may be arranged in at least a partial region of the top surface of the first protective part. In such a case, the second protective part is arranged in at least a partial region of at least the top surface of the first protective part, and in a region facing at least a part of the thermosensitive recording layer.

[0136] The second protective part being arranged on "at least the top surface" of the thermosensitive recording layer means that the second protective part may be arranged on a surface other than the top surface of the thermosensitive recording layer, for example, on a side surface. When the second protective part is arranged on the side surface of the thermosensitive recording layer, the second protective part arranged on the top surface of the thermosensitive recording layer and the second protective part arranged on the side surface of the thermosensitive recording layer may be arranged continuously or may not be arranged continuously.

[0137] For example, when the second protective part is laminated directly on the top surface of the thermosensitive recording layer and arranged directly on the side surface of the thermosensitive recording layer, the second protective part on the top surface of the thermosensitive recording layer and the second protective part on the side surface of the thermosensitive recording layer may be arranged continuously. When the second protective part is laminated on the top surface of the thermosensitive recording layer via another layer or member and is arranged directly on the side surface of the thermosensitive recording layer, the second protective part on the top surface of the thermosensitive recording layer and the second protective part on the side surface of the thermosensitive recording layer may not be arranged continuously.

[0138] As used herein, the second protective part being arranged on "at least the top surface" of the thermosensitive recording layer means that the second protective part may be arranged so that the area of the second protective part is 100% of the total area of the top surface of the thermosensitive recording layer (that is, the second protective part may be arranged over the total area of at least the top surface of the thermosensitive recording layer), or may bearranged so that the area of the second protective part exceeds 100% (that is, the second protective part may be arranged beyond the top surface of the thermosensitive recording layer). However, it is preferable that the second protective part is not arranged beyond the top surface of the support.

[0139] A composition of the material of the first protective part and a composition of the material of the second protective part may be the same or different. The first protective part and the second protective part may be arranged in the same layer or in different layers. The first protective part and the second protective part may be arranged separately in different regions, or may be arranged continuously. The composition of the material and arrangements of the first protective part and the second protective part may be combined. For example, the composition of the material of the first protective part is the same as the composition of the material of the second protective part, the first protective part and the second protective part are arrange in the same layer, and the first protective part and the second protective part are arranged in different regions at a distance from each other; the composition of the material of the first protective part is the same as the composition of the material of the second protective part, the first protective part and the second protective part are arrange in the same layer, and the first protective part and the second protective part are arranged continuously; the composition of the material of the first protective part is the same as the composition of the material of the second protective part, the first protective part and the second protective part are arrange in different layers, and the first protective part and the second protective part are arranged in different regions at a distance from each other (that is, the first protective part and the second protective part are laminated via another layer or member); the composition of the material of the first protective part is the same as the composition of the material of the second protective part, the first protective part and the second protective part are arrange in different layers, and the first protective part and the second protective part are arranged continuously; the composition of the material of the first protective part and the composition of the material of the second protective part are different compositions, the first protective part and the second protective part are arrange in the same layer, and the first protective part and the second protective part are arranged in different regions at a distance from each other; the composition of the material of the first protective part and the composition of the material of the second protective part are different compositions, the first protective part and the second protective part are arrange in the same layer, and the first protective part and the second protective part are arranged continuously; the composition of the material of the first protective part and the composition of the material of the second protective part are different compositions, the first protective part and the second protective part are arrange in different layers, and the first protective part and the second protective part are arranged in different regions at a distance from each other (that is, the first protective part and the second protective part are laminated via another layer or member); the composition of the material of the first protective part and the composition of the material of the second protective part are differentcompositions, the first protective part and the second protective part are arrange in different layers, and the first protective part and the second protective part are arranged continuously.

[0140] When the composition of the material of the first protective part and the composition of the material of the second protective part are different, the boundary between the first protective part and the second protective part can be distinguished even when the first protective part and the second protective part are arranged continuously. On the other hand, in the thermosensitive recording medium according to the present disclosure, when the composition of the material of the first protective part and the composition of the material of the second protective part are the same and the first protective part and the second protective part are arranged continuously, the boundary cannot be distinguished. Therefore, the first protective part is arranged in at least a partial region of at least the top surface of the color ink layer, and the second protective part is arranged on at least the top surface of the thermosensitive recording layer; however, when the composition of the material of the first protective part and the composition of the material of the second protective part are the same and the first protective part and the second protective part are arranged continuously, the first protective part and the second protective part are not distinguished and may function as a "protective part" together.

[0141] When the composition of the material of the first protective part and the composition of the material of the second protective part are different, the boundary between the both units may be confirmed, for example, by each analyzing the composition of the materials, such as the shape and element types of the pigments (fillers) in the first protective part and the second protective part by using a scanning electron microscope energy dispersive X-ray spectroscopy (SEM-EDX).

[0142] The second protective part contains a binder resin, and preferably further contains a crosslinking agent, a pigment (filler), a wax, and the like, and may further optionally contain other components. The binder resin, the crosslinking agent, the pigment (filler), the wax, and other components in the second protective part can be the same as those in the first protective part.

[0143] When the composition of the material of the first protective part is different from the composition of the material of the second protective part, for example, the first protective part may have the composition containing at least a binder resin and a crosslinking agent, but not a pigment (filler) or a wax, and the second protective part can have the composition containing at least a binder resin, a crosslinking agent, a pigment (filler), and a wax.

[0144] When the composition of the material of the first protective part is different from the composition of the material of the second protective part, for example, the first protective partcan have the composition containing at least a binder resin, a crosslinking agent, a pigment (filler), and a wax, and the second protective part can have the composition containing at least a binder resin and a crosslinking agent, but not a pigment (filler) or a wax.

[0145] When the composition of the material of the first protective part and the composition of the material of the second protective part are the same, for example, the first protective part and the second protective part may both have the composition containing at least a binder resin and a crosslinking agent, or both may have the composition containing at least a binder resin, a crosslinking agent, a pigment (filler), and a wax.

[0146] A shape, a structure, a size, the number, and arrangement of the second protective part are not particularly limited as long as the second protective part is arranged on at least the top surface of the thermosensitive recording layer, and can be appropriately selected depending on the purpose. The second protective part is preferably in the form of a layer.

[0147] The average thickness of the second protective part is not particularly limited and can be selected at random as necessary, but is preferably 0.5 pm or more and 5 pm or less, and more preferably 1 pm or more and 3 pm or less.

[0148] As used herein, the "average thickness" of the second protective part means an average value calculated from the thicknesses at 20 points selected at random from the second protective part, after measuring the thicknesses at such 20 points.The thickness of the second protective part can be measured by using a cross-sectional sample preparation device (for example, a cross-section polisher SM-09020CP, manufactured by JEOL Ltd.) to cut the thermosensitive recording medium in the thickness direction (lamination direction) to expose the cross-section surface, and then observing the crosssection surface with a scanning electron microscope (SEM) (for example, S-3700, manufactured by Hitachi High-Tech Corporation).

[0149] <Other Members>Other members in the thermosensitive recording medium according to the present disclosure are not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include, but are not limited to, a back layer, an under layer, a heat seal layer, a release layer, and an adhesive layer.

[0150] «Back Layer»The back layer may be arranged to prevent curling of the thermosensitive recording medium, but when the thermosensitive recording medium requires transparency, it is preferable not to arrange the back layer.

[0151] When the back layer is arranged in the thermosensitive recording medium, the back layer is preferably arranged on the surface of the support opposite to the surface on which the thermosensitive recording layer is arranged, that is, on the bottom surface of the support.

[0152] The back layer is not particularly limited and can be appropriately selected depending on the purpose, but contains a binder resin and a pigment (filler), and may further optionally contain other components such as a lubricant and a coloring pigment. The binder resin and the lubricant used may be similar to those in the thermosensitive recording layer. The pigment (filler) similar to that in the second protective part may be employed for the pigment (filler). The coloring pigment is not particularly limited and can be appropriately selected from known pigments.

[0153] The average thickness of the back layer is not particularly limited and may be appropriately selected depending on the purpose, but is preferably 0.1 pm or more and 20 pm or less, and more preferably 0.3 pm or more and 10 pm or less.

[0154] «Under Layer»The under layer may be provided for the purpose of improving the color development sensitivity of the thermosensitive recording medium, but when the thermosensitive recording medium requires transparency, it is preferable not to provide the under layer.

[0155] When the under layer is arranged in the thermosensitive recording medium, the under layer is preferably arranged between the support and the thermosensitive recording layer.

[0156] When the under layer is arranged, the under layer is not particularly limited and can be appropriately selected depending on the purpose, but it is preferable that the under layer contains an adhesive resin, thermoplastic hollow resin particles, and the like, and further optionally contains other components.

[0157] The thermoplastic hollow resin particles are minute hollow particles including a thermoplastic resin as a shell and containing air or other gases inside, and are already in a foamed state.

[0158] The average particle size (outer particle diameter) of the thermoplastic hollow resin particles is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.2 pm or more and 20 pm or less, and more preferably 2 pm or more and 5 pm or less. When the average particle size of the thermoplastic hollow resin particles is 0.2 pm or more, it is technically easy to produce hollow particles, and the undercoat layer can function satisfactorily. On the other hand, when the average particle size is 20 pm or less, the smoothness of the surface after applying and drying the thermoplastic hollow resin particles is not reduced, and the application of the thermosensitive recording layer is less likely tobecome uneven, making it unnecessary to apply more than the amount of thermosensitive recording layer forming liquid necessary to achieve uniformity. Therefore, it is desirable that the average particle size of the thermoplastic hollow resin particles is within the above range and at the same time, the particle size distribution has a uniform peak with little variation.

[0159] The hollow ratio of the thermoplastic hollow resin particles is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 30% or more and 95% or less, more preferably 50% or more and 95% or less, and even more preferably 80% or more and 95% or less. When the hollow rate of the thermoplastic hollow resin particles is 30% or more, the heat insulating properties are sufficient, and the thermal energy from the thermal head is not released to the outside of the thermosensitive recording medium through the support, so that the sensitivity improving effect can be sufficiently obtained.

[0160] As used herein, the hollow ratio of the thermoplastic hollow resin particles is based on the ratio of the outer diameter of the thermoplastic hollow resin particles to the inner diameter (diameter of the hollow portion) of the thermoplastic hollow resin particles and is represented by the following formula 1.[Formula 1]Hollow ratio (%) of thermoplastic hollow resin particle = (Inner diameter of thermoplastic hollow resin parti cle / Outer diameter of thermoplastic hollow resin particle) x 100

[0161] It is noted that as described above, the thermoplastic hollow resin particles have a shell formed of a thermoplastic resin, and the thermoplastic resin is not particularly limited and can be appropriately selected depending on the purpose. Examples of the thermoplastic resin include, but are not limited to, styrene-acrylic resins, polystyrene resins, acrylic resins, polyethylene resins, polypropylene resins, polyacetal resins, chlorinated polyether resins, polyvinyl chloride resins, and copolymer resins mainly formed of vinylidene chloride and acrylonitrile. Among such thermoplastic resins, styrene-acrylic resins and copolymer resins mainly formed of vinylidene chloride and acrylonitrile are preferable for the thermoplastic resin, because of a high hollow ratio, a small variation in particle size, and are suitable for blade coating.

[0162] «Heat Seal Layer»The heat seal layer is formed by laminating films formed of LDPE (low density polyethylene) used as a sealant, and therefore, the heat seal layer can be welded by heating heat seal layers in a state of being in close contact with each other. Taking advantage of such a property, a packaging sheet formed into a bag shape can be sealed, that is, heat-sealed, by heating the packaging sheet under the same conditions.Therefore, any material that allows heat sealing, that is, has heat sealability, can be used to form the heat seal layer, without being limited to LDPE.

[0163] When the heat seal layer is arranged on the thermosensitive recording medium, the heat seal layer is preferably arranged on the side of the support opposite to the side on which the thermosensitive recording layer is arranged, that is, the bottom surface of the support; when arranged on the side of the support on which the thermosensitive recording layer is arranged, the heat seal layer is preferably arranged between the support and the thermosensitive recording layer or the color ink layer. The heat seal layer may be arranged on one or both sides of the thermosensitive recording layer.

[0164] Examples of suitably used substances having heat sealability include, but are not limited to, films formed of high density polyethylene (HDPE), cast polypropylene (CPP), oriented polypropylene (OPP), an ethylene-vinyl acetate copolymer (EVA) or the like, and other examples may include polyolefin resins such as polyethylene and polypropylene; vinyl acetate-based resins such as ethylene- vinyl acetate copolymers (olefin-vinyl acetate copolymers, and the like); acrylic resins such as ethylene-(meth)acrylic acid copolymers and ionomer [olefm-(meth)acrylic acid copolymers, metal cross-linked products thereof, or the like.]. Also, the heat seal layer may be formed by using a well-known heat sealable adhesive. It is preferable to use a material that becomes transparent after forming the heat seal layer to see a packaged item.

[0165] The average thickness of the heat seal layer is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoints of the transparency and the seal strength, the average thickness is preferably 5 pm or more and 50 pm or less, and more preferably 10 pm or more and 30 pm or less.

[0166] «Release Layer»The release layer may be provided to protect the thermosensitive recording medium from abrasion and the like. The release layer is released when the thermosensitive recording medium is used.

[0167] When the release layer is provided on the thermosensitive recording medium, the release layer is preferably provided on the top surface of the first protective part and / or the second protective part.

[0168] The release layer contains a release agent. The release agent is not particularly limited and can be appropriately selected depending on the purpose. Examples of the release agent include, but are not limited to, ultraviolet curing silicone, heat curing silicone, solventless silicone, solvent type silicone, emulsion type silicone, and fluorine-based release agents.

[0169] «Adhesive Layer»When the thermosensitive recording medium is used adhesively, the adhesive layer may be arranged. The adhesive layer is preferably arranged on the surface of the support opposite to the surface on which the thermosensitive recording layer is arranged, that is, on the bottom surface of the support. When the thermosensitive recording medium has the back layer, it is preferable to place the adhesive layer on the bottom surface of the back layer, that is, on the surface of the back layer opposite to the surface in contact with the support.

[0170] The main component of the adhesive contained in the adhesive layer is preferably at least one selected from an acrylic resin obtained by emulsion polymerization of a monomer mainly formed of at least one kind of (meth)acrylic acid alkyl ester having an alkyl group, an acrylic acid ester-styrene copolymer, and an acrylic acid ester-methacrylic acid ester-styrene copolymer.

[0171] Here, the "main component" of the adhesive means a component formed only of a resin, excluding additives such as penetrating agents, film-forming assistants, defoamers, rust inhibitors, thickeners, wetting agents, preservatives, UV absorbers, light stabilizers, pigments, and inorganic fillers that are optionally blended into the adhesive. As used herein, "(meth)acrylic" means "acrylic or methacrylic".

[0172] Specific examples of (meth)acrylic acid alkyl esters include, but are not limited to, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, and n-dodecyl (meth)acrylate. Such (meth)acrylic acid alkyl esters may be used alone or in combination of two or more types.

[0173] As used herein, the "average thickness" of each layer serving as the other members means an average value calculated from the thicknesses of each layer at 20 points selected at random from each layer, after measuring the thicknesses at such 20 points. The thickness of each layer can be measured by observing the cross-section surface with an SEM in the same manner as in measuring the thickness of the thermosensitive recording layer.

[0174] Here, an embodiment of the thermosensitive recording medium according to the present disclosure will be described in detail with reference to the drawings.In FIG. lAto FIG. 13B, a Y-axis direction indicates the lamination direction of a thermosensitive recording medium 100, that is, the thickness direction of the thermosensitive recording medium 100. An X-axis direction and a Z-axis direction are perpendicular to the Y-axis direction. The X-axis direction and the Z-axis direction indicate the surface directions of the support. The X-axis direction is perpendicular to the Z-axis direction.

[0175] [First Embodiment]FIG. 1 A is a schematic top view of a thermosensitive recording medium according to a firstembodiment. FIG. IB is a schematic cross-sectional view taken along line IB-IB in FIG. 1 A.

[0176] The thermosensitive recording medium 100 according to the first embodiment includes a support 1, a thermosensitive recording layer 2 arranged in a partial region of a top surface 1 A of the support 1, a color ink layer 3 arranged in a partial region of the top surface 1 A of the support 1, a first protective part 4 arranged on a top surface of the color ink layer 3, and a second protective part 5 arranged on a top surface of the thermosensitive recording layer 2. The color ink layer 3 is arranged in a partial region of the top surface 1 A of the support 1 in a region different from the thermosensitive recording layer 2 arranged in a partial region of the top surface 1 A of the support 1. As a result, a region where the color ink layer 3 and the first protective part 4 are arranged in a laminated state is separated from a region where the thermosensitive recording layer 2 and the second protective part 5 are arranged in a laminated state.

[0177] The first protective part 4 is arranged so that the area of the first protective part 4 covers the total area of the top surface of the color ink layer 3, that is, is 100% of the total area of the top surface of the color ink layer 3. Similarly, the second protective part 5 is arranged so that the area of the second protective part 5 covers the total area of the top surface of the thermosensitive recording layer 2, that is, is 100% of the total area of the top surface of the thermosensitive recording layer 2.

[0178] In the thermosensitive recording medium 100 according to the first embodiment, the first protective part 4 is arranged on the top surface of the color ink layer 3, so that when a thermal head presses the thermosensitive recording medium 100 in the Y-axis direction from the top surface 1 A of the support 1 toward a bottom surface IB of the support 1, and when the thermal head moves in the X-Z axis direction, the abrasion resistance of the color ink layer 3 is improved, and printing defects caused by the accumulation of ink residue on the thermal head due to abrasion of the color ink layer 3 can be prevented. The thermosensitive recording medium 100 according to the first embodiment includes the second protective part 5 arranged on the top surface of the thermosensitive recording layer 2, and thus, the abrasion resistance of the thermosensitive recording layer 2 can also be improved when the thermal head presses the thermosensitive recording medium 100 in the Y-axis direction from the top surface 1 A of the support 1 toward the bottom surface IB of the support 1, and when the thermal head moves in the X-Z axis direction.

[0179] The composition of the material of the first protective part 4 and the composition of the material of the second protective part 5 may be the same as or different from each other. When the first protective part 4 and the second protective part 5 contain a pigment (filler) and a wax in addition to a binder resin and a crosslinking agent, the strength is improved and the abrasion resistance is further improved compared to a case where the first protective part 4and the second protective part 5 do not contain a pigment (filler) and a wax, and printing defects caused by the accumulation of ink residue on the thermal head due to abrasion of the color ink layer 3 can be further prevented. This is also preferable in that the lubrication of the color ink layer 3 with respect to the thermal head is improved.In the first protective part 4 and the second protective part 5, it is preferable that at least the second protective part 5 contains a pigment (filler) and a wax.

[0180] [Second Embodiment]FIG. 2A is a schematic top view of a thermosensitive recording medium according to a second embodiment. FIG. 2B is a schematic cross-sectional view taken along line IIB-IIB in FIG.2A.

[0181] The thermosensitive recording medium 100 according to the second embodiment differs from the thermosensitive recording medium 100 according to the first embodiment in that the first protective part 4 is arranged on a top surface and a side surface of the color ink layer 3, and the second protective part 5 is arranged on a top surface and a side surface of the thermosensitive recording layer 2. That is, in the thermosensitive recording medium 100 according to the second embodiment, the first protective part 4 is arranged so that the area of the first protective part 4 exceeds 100% of the total area of the top surface of the color ink layer 3, and the first protective part 4 arranged on the top surface of the color ink layer 3 and the first protective part 4 arranged on the side surface of the color ink layer 3 are arranged continuously. Similarly, in the thermosensitive recording medium 100 according to the second embodiment, the second protective part 5 is arranged so that the area of the second protective part 5 exceeds 100% of the total area of the top surface of the thermosensitive recording layer 2, and the second protective part 5 arranged on the top surface of the thermosensitive recording layer 2 and the second protective part 5 arranged on the side surface of the thermosensitive recording layer 2 are arranged continuously.

[0182] In the thermosensitive recording medium 100 according to the second embodiment, the first protective part 4 is arranged not only on the top surface but also on the side surface of the color ink layer 3, and thus, when the thermal head moves in the X-Z axis direction, the abrasion resistance of the side surface of the color ink layer 3 is further improved, and printing defects caused by the accumulation of ink residue on the thermal head due to abrasion of the side surface of the color ink layer 3 can be further prevented.

[0183] [Third Embodiment]FIG. 3 A is a schematic top view of a thermosensitive recording medium according to a third embodiment. FIG. 3B is a schematic cross-sectional view taken along line IIIB-IIIB in FIG.3A.

[0184] The thermosensitive recording medium 100 according to the third embodiment includes the support 1, the color ink layer 3 arranged in a partial region of the top surface 1 A of the support 1, the thermosensitive recording layer 2 arranged in a partial region of the top surface of the color ink layer 3, the first protective part 4 arranged in a partial region of the top surface of the color ink layer 3, and the second protective part 5 arranged on the top surface of the thermosensitive recording layer 2. The thermosensitive recording layer 2 is arranged in a partial region of the top surface 1 A of the support 1 via the color ink layer 3. As a result, the first protective part 4 and the second protective part 5 are arranged continuously. The first protective part 4 is arranged on the side surface of the thermosensitive recording layer 2.

[0185] The first protective part 4 is arranged so that the area of the first protective part 4 is less than 100% of the total area of the top surface of the color ink layer 3. In the thermosensitive recording medium 100 according to the third embodiment, the second protective part 5 is arranged so that the area of the second protective part 5 is 100% of the total area of the top surface of the thermosensitive recording layer 2.

[0186] The thermosensitive recording medium 100 according to the third embodiment includes the first protective part 4 in a part of the top surface of the color ink layer 3, and the second protective part 5 via the thermosensitive recording layer 2 on another positional portion on the top surface of the color ink layer 3, and thus, when the thermal head presses the thermosensitive recording medium 100 in the Y-axis direction from the top surface 1 A of the support 1 toward the bottom surface IB of the support 1, and when the thermal head moves in the X-Z axis direction, the abrasion resistance of the color ink layer 3 is improved, and printing defects caused by the accumulation of ink residue on the thermal head due to abrasion of the color ink layer 3 can be prevented. The thermosensitive recording medium 100 according to the third embodiment includes the second protective part 5 on the top surface of the thermosensitive recording layer 2, and thus, the abrasion resistance of the thermosensitive recording layer 2 can also be improved when the thermal head presses the thermosensitive recording medium 100 in the Y-axis direction from the top surface 1 A of the support 1 toward the bottom surface IB of the support 1, and when the thermal head moves in the X-Z axis direction.

[0187] The composition of the material of the first protective part 4 and the composition of the material of the second protective part 5 according to the third embodiment may be the same as or different from each other, similarly to the first embodiment.

[0188] [Fourth Embodiment]FIG. 4A is a schematic top view of a thermosensitive recording medium according to a fourth embodiment. FIG. 4B is a schematic cross-sectional view taken along line IVB-IVB in FIG.4A.

[0189] The thermosensitive recording medium 100 according to the fourth embodiment differs from the thermosensitive recording medium 100 according to the third embodiment in that the first protective part 4 is arranged not only on the top surface of the color ink layer 3 but also on the side surface thereof. That is, in the thermosensitive recording medium 100 according to the fourth embodiment, the first protective part 4 is arranged so that the area of the first protective part 4 is less than 100% of the total area of the top surface of the color ink layer 3, and the first protective part 4 arranged on the top surface of the color ink layer 3 and the first protective part 4 arranged on the side surface of the color ink layer 3 are arranged continuously.

[0190] In the thermosensitive recording medium 100 according to the fourth embodiment, the second protective part 5 is arranged so that the area of the second protective part 5 is 100% of the total area of the top surface of the thermosensitive recording layer 2. The first protective part 4 and the second protective part 5 are arranged continuously. Therefore, the first protective part 4 is arranged on the side surface of the thermosensitive recording layer 2.

[0191] In the thermosensitive recording medium 100 according to the fourth embodiment, the first protective part 4 is arranged not only on the top surface but also on the side surface of the color ink layer 3, and thus, as compared to the thermosensitive recording medium 100 according to the third embodiment, when the thermal head moves in the X-Z axis direction, the abrasion resistance of the side surface of the color ink layer 3 is further improved, and printing defects caused by the accumulation of ink residue on the thermal head due to abrasion of the side surface of the color ink layer 3 can be further prevented.

[0192] [Fifth Embodiment]FIG. 5 A is a schematic top view of a thermosensitive recording medium according to a fifth embodiment. FIG. 5B is a schematic cross-sectional view taken along line VB-VB in FIG.5A.

[0193] The thermosensitive recording medium 100 according to the fifth embodiment includes the support 1, the color ink layer 3 arranged in a partial region of the top surface 1 A of the support 1, the thermosensitive recording layer 2 arranged in a partial region of the top surface of the color ink layer 3, the first protective part 4 arranged on the top surface of the color ink layer 3, and on the top surface and the side surface of the thermosensitive recording layer 2, and the second protective part 5 arranged in at least a part of the top surface of the first protective part 4. The thermosensitive recording layer 2 is arranged in a partial region of the top surface 1 A of the support 1 via the color ink layer 3. The first protective part 4 is arranged continuously on the top surface and the side surface of the thermosensitive recording layer 2 and on the top surface of the color ink layer 3. The second protective part 5 is arranged on thetop surface of the thermosensitive recording layer 2 via the first protective part 4, in a region facing the thermosensitive recording layer 2. As a result, the first protective part 4 and the second protective part 5 are arranged continuously.

[0194] That is, in the thermosensitive recording medium 100 according to the fifth embodiment, the first protective part 4 is arranged in a region other than the region where the thermosensitive recording layer 2 is arranged on the top surface of the color ink layer 3, and therefore, the first protective part 4 is arranged so that the area of the first protective part 4 is less than 100% of the total area of the top surface of the color ink layer 3. In the thermosensitive recording medium 100 according to the fifth embodiment, the second protective part 5 is arranged so that the area of the second protective part 5 is 100% of the total area of the top surface of the thermosensitive recording layer 2.

[0195] The thermosensitive recording medium 100 according to the fifth embodiment includes the first protective part 4 and the second protective part 5 on the top surface of the thermosensitive recording layer 2, and therefore, the abrasion resistance of the thermosensitive recording layer 2 can be further improved when the thermal head presses the thermosensitive recording medium 100 in the Y-axis direction from the top surface 1 A of the support 1 toward the bottom surface IB of the support 1, and when the thermal head moves in the X-Z axis direction.

[0196] The composition of the material of the first protective part 4 and the composition of the material of the second protective part 5 according to the fifth embodiment may be the same as or different from each other, similarly to the first embodiment.

[0197] [Sixth Embodiment]FIG. 6A is a schematic top view of a thermosensitive recording medium according to a sixth embodiment. FIG. 6B is a schematic cross-sectional view taken along line VIB-VIB in FIG.6A.

[0198] The thermosensitive recording medium 100 according to the sixth embodiment differs from the thermosensitive recording medium 100 according to the fifth embodiment in that the first protective part 4 is arranged not only on the top surface of the color ink layer 3 but also on the side surface thereof. That is, in the thermosensitive recording medium 100 according to the sixth embodiment, the first protective part 4 is arranged in a region other than the region where the thermosensitive recording layer 2 is arranged on the top surface of the color ink layer 3, and the first protective part 4 arranged on the top surface of the color ink layer 3 and the first protective part 4 arranged on the side surface of the color ink layer 3 are arranged continuously. The first protective part 4 and the second protective part 5 are arranged continuously.

[0199] In the thermosensitive recording medium 100 according to the sixth embodiment, when an area X of the top surface of the thermosensitive recording layer 2 and an area Y obtained by subtracting the area of the inside surrounded by the end of the color ink layer 3 indicated by the dashed line in FIG. 6 A from an area of the inside surrounded by the end of the first protective part 4 indicated by the solid line in FIG. 6A is X = Y, the area of the first protective part 4 is 100% of the total area of the top surface of the color ink layer 3, when X > Y, the area of the first protective part 4 is less than 100% of the total area of the top surface of the color ink layer 3, and when X < Y, the area of the first protective part 4 is greater than 100% of the total area of the top surface of the color ink layer 3.

[0200] In the thermosensitive recording medium 100 according to the sixth embodiment, the second protective part 5 is arranged so that the area of the second protective part 5 is 100% of the total area of the top surface of the thermosensitive recording layer 2.

[0201] In the thermosensitive recording medium 100 according to the sixth embodiment, the first protective part 4 is arranged not only on the top surface but also on the side surface of the color ink layer 3, and thus, as compared to the thermosensitive recording medium 100 according to the fifth embodiment, when the thermal head moves in the X-Z axis direction, the abrasion resistance of the side surface of the color ink layer 3 is further improved, and printing defects caused by the accumulation of ink residue on the thermal head due to abrasion of the side surface of the color ink layer 3 can be further prevented.

[0202] [Seventh Embodiment]FIG. 7A is a schematic top view of a thermosensitive recording medium according to a seventh embodiment. FIG. 7B is a schematic cross-sectional view taken along line VIIB-VIIB in FIG. 7A.

[0203] The thermosensitive recording medium 100 according to the seventh embodiment differs from the thermosensitive recording medium 100 according to the fifth embodiment in that the second protective part 5 is arranged so that the area of the second protective part 5 is greater than 100% of the total area of the top surface of the thermosensitive recording layer 2.

[0204] [Eighth Embodiment]FIG. 8A is a schematic top view of a thermosensitive recording medium according to an eighth embodiment. FIG. 8B is a schematic cross-sectional view taken along line VIIIB-VIIIB in FIG. 8A.

[0205] The thermosensitive recording medium 100 according to the eighth embodiment differs from the thermosensitive recording medium 100 according to the fifth embodiment in that thesecond protective part 5 is arranged so that the area of the second protective part 5 is greater than 100% of the total area of the top surface of the thermosensitive recording layer 2. The thermosensitive recording medium 100 according to the eighth embodiment is arranged such that the area of the second protective part 5 is 100% of the total area of the top surface of the first protective part 4.

[0206] [Ninth Embodiment]FIG. 9A is a schematic top view of a thermosensitive recording medium according to a ninth embodiment. FIG. 9B is a schematic cross-sectional view taken along line IXB-IXB in FIG.9A.

[0207] The thermosensitive recording medium 100 according to the ninth embodiment differs from the thermosensitive recording medium 100 according to the seventh embodiment in that the first protective part 4 is arranged not only on the top surface of the color ink layer 3 but also on the side surface. That is, in the thermosensitive recording medium 100 according to the nineth embodiment, the first protective part 4 is arranged in a region other than the region where the thermosensitive recording layer 2 is arranged on the top surface of the color ink layer 3, and the first protective part 4 arranged on the top surface of the color ink layer 3 and the first protective part 4 arranged on the side surface of the color ink layer 3 are arranged continuously. The first protective part 4 and the second protective part 5 are arranged continuously.

[0208] In the thermosensitive recording medium 100 according to the ninth embodiment, when the area X of the top surface of the thermosensitive recording layer 2 and the area Y obtained by subtracting the area of the inside surrounded by the end of the color ink layer 3 indicated by the dashed line in FIG. 9A from the area of the inside surrounded by the end of the first protective part 4 indicated by the solid line in FIG. 9A is X = Y, the area of the first protective part 4 is 100% of the total area of the top surface of the color ink layer 3, when X > Y, the area of the first protective part 4 is less than 100% of the total area of the top surface of the color ink layer 3, and when X < Y, the area of the first protective part 4 is greater than 100% of the total area of the top surface of the color ink layer 3.

[0209] In the thermosensitive recording medium 100 according to the ninth embodiment, the first protective part 4 is arranged not only on the top surface but also on the side surface of the color ink layer 3, and thus, as compared to the thermosensitive recording medium 100 according to the seventh embodiment, when the thermal head moves in the X-Z axis direction, the abrasion resistance of the side surface of the color ink layer 3 is further improved, and printing defects caused by the accumulation of ink residue on the thermal head due to abrasion of the side surface of the color ink layer 3 can be further prevented.

[0210] [Tenth Embodiment]FIG. 10A is a schematic top view of a thermosensitive recording medium according to a tenth embodiment. FIG. 1 OB is a schematic cross-sectional view taken along line XB-XB in FIG.10 A.

[0211] The thermosensitive recording medium 100 according to the tenth embodiment differs from the thermosensitive recording medium 100 according to the eighth embodiment in that the first protective part 4 is arranged not only on the top surface of the color ink layer 3 but also on the side surface. That is, in the thermosensitive recording medium 100 according to the tenth embodiment, the first protective part 4 is arranged in a region other than the region where the thermosensitive recording layer 2 is arranged on the top surface of the color ink layer 3, and the first protective part 4 arranged on the top surface of the color ink layer 3 and the first protective part 4 arranged on the side surface of the color ink layer 3 are arranged continuously. The first protective part 4 and the second protective part 5 are arranged continuously.

[0212] In the thermosensitive recording medium 100 according to the tenth embodiment, when the area X of the top surface of the thermosensitive recording layer 2 and the area Y obtained by subtracting the area of the inside surrounded by the end of the color ink layer 3 indicated by the dashed line in FIG. 10A from the area of the inside surrounded by the end of the first protective part 4 indicated by the dashed line (that matches the end of the second protective part 5 indicated by the solid line) in FIG. 10A is X = Y, the area of the first protective part 4 is 100% of the total area of the top surface of the color ink layer 3, when X > Y, the area of the first protective part 4 is less than 100% of the total area of the top surface of the color ink layer 3, and when X < Y, the area of the first protective part 4 is greater than 100% of the total area of the top surface of the color ink layer 3.

[0213] The thermosensitive recording medium 100 according to the tenth embodiment has the first protective part 4 arranged not only on the top surface but also on the side surface of the color ink layer 3, and therefore, compared to the thermosensitive recording medium 100 according to the eighth embodiment, the abrasion resistance of the side surface of the color ink layer 3 is improved when the thermal head moves in the X-Z axis direction, and printing defects caused by the accumulation of ink residue on the thermal head due to abrasion of the side surface of the color ink layer 3 can be prevented.

[0214] [Eleventh Embodiment]FIG. 11 A is a schematic top view of a thermosensitive recording medium according to an eleventh embodiment. FIG. 1 IB is a schematic cross-sectional view taken along line XIB-XIB in FIG. 11 A.

[0215] The thermosensitive recording medium 100 according to the eleventh embodiment includes the support 1, the thermosensitive recording layer 2 arranged in a partial region of the top surface 1 A of the support 1, the color ink layer 3 arranged in a partial region of the top surface 1 A of the support 1, the first protective part 4 arranged on the top surface and the side surface of the color ink layer 3, and on the top surface and the side surface of the thermosensitive recording layer 2, and the second protective part 5 arranged, via the first protective part 4, on the top surface of the thermosensitive recording layer 2. The color ink layer 3 is arranged in a partial region of the top surface 1 A of the support 1 in a region different from the thermosensitive recording layer 2 arranged in a partial region of the top surface 1 A of the support 1. The first protective part 4 and the second protective part 5 are arranged continuously.

[0216] That is, the first protective part 4 is arranged so that the area of the first protective part 4 is greater than 100% of the total area of the top surface of the color ink layer 3. The second protective part 5 is arranged so that the area of the second protective part 5 is greater than 100% of the total area of the top surface of the thermosensitive recording layer 2.

[0217] The thermosensitive recording medium 100 according to the eleventh embodiment includes the first protective part 4 arranged continuously on the top surface and the side surface of the color ink layer 3 and on the top surface and the side surface of the thermosensitive recording layer 2, and the second protective part 5 arranged via the first protective part 4 on the top surface of the color ink layer 3, and thus, when the thermal head presses the thermosensitive recording medium 100 in the Y-axis direction from the top surface 1 A of the support 1 toward the bottom surface IB of the support 1, and when the thermal head moves in the X-Z axis direction, the abrasion resistance of the color ink layer 3 is improved, and printing defects caused by the accumulation of ink residue on the thermal head due to abrasion of the color ink layer 3 can be prevented. The thermosensitive recording medium 100 according to the eleventh embodiment includes the second protective part 5 arranged via the first protective part 4 on the top surface of the thermosensitive recording layer 2, and thus, the abrasion resistance of the thermosensitive recording layer 2 can also be improved when the thermal head presses the thermosensitive recording medium 100 in the Y-axis direction from the top surface 1 A of the support 1 toward the bottom surface IB of the support 1, and when the thermal head moves in the X-Z axis direction compared to the thermosensitive recording medium 100 according to the second embodiment.

[0218] The composition of the material of the first protective part 4 and the composition of the material of the second protective part 5 according to the eleventh embodiment may be the same as or different from each other, similarly to the first embodiment.

[0219] [Twelfth Embodiment]FIG. 12A is a schematic top view of a thermosensitive recording medium according to a twelfth embodiment. FIG. 12B is a schematic cross-sectional view taken along line XIIB-XIIB in FIG. 12 A.

[0220] The thermosensitive recording medium 100 according to the twelfth embodiment differs from the thermosensitive recording medium 100 according to the eleventh embodiment in that not only the second protective part 5 is arranged so that the area of the second protective part 5 exceeds 100% of the total area of the top surface of the thermosensitive recording layer 2, but also that the second protective part 5 is arranged so that the area of the top surface of the second protective part 5 is 100% of the area of the top surface of the first protective part 4.

[0221] [Thirteenth Embodiment]FIG. 13 A is a schematic top view of a thermosensitive recording medium according to a thirteenth embodiment. FIG. 13B is a schematic cross-sectional view taken along line XIIIB-XIIIB in FIG. 13 A.

[0222] The thermosensitive recording medium 100 according to the thirteenth embodiment differs from the thermosensitive recording medium 100 according to the second embodiment in that the side surface of the first protective part 4 and the side surface of the second protective part 5 are continuous.

[0223] It is noted that when the composition of the material of the first protective part 4 and the composition of the material of the second protective part 5 are the same, when M = N is established, where M indicates a total thickness of an average thickness of the first protective part 4 and an average thickness of the second protective part 5 in the thermosensitive recording medium 100 according to the twelfth embodiment and N indicates an average thickness of the first protective part 4 and an average thickness of the second protective part 5 continuous therewith in the thermosensitive recording medium 100 according to the thirteenth embodiment, the thermosensitive recording medium 100 according to the twelfth embodiment and the thermosensitive recording medium 100 according to the thirteenth embodiment have the same configuration.

[0224] <Applications>The applications of the thermosensitive recording medium according to the present disclosure are not particularly limited and can be appropriately selected depending on the purpose.Examples thereof include, but are not limited to, labels used in the POS (Point of Sales) field to be affixed to fresh food, boxed lunches, and side dishes; and bands to be wrapped around fresh food, boxed lunches, and side dishes. Through the use in the above applications, the visibility of the contents is improved, and a consumer can select a product while checking the contents. Examples of other applications include tickets, tags, and cards. More specifically,examples include ticket vending machines, a field of issuing receipts, vouchers, and the like; packaging tags in the aircraft industry, pill cases, and pill bottles; and output paper for facsimile machines in a field of copying books and documents.

[0225] A method for manufacturing the thermosensitive recording medium is not particularly limited and can be appropriately selected from well-known methods, but the method for manufacturing the thermosensitive recording medium according to the present disclosure described below can be suitably used.

[0226] (Method of Manufacturing Thermosensitive Recording Medium)The method for manufacturing a thermosensitive recording medium according to the present disclosure includes forming a thermosensitive recording layer, forming a color ink layer, forming a first protective part, and forming a second protective part.The method for manufacturing a thermosensitive recording medium according to the present disclosure may further optionally include other processes.

[0227] The method for manufacturing a thermosensitive recording medium according to the present disclosure can suitably produce the thermosensitive recording medium according to the present disclosure.

[0228] <Forming Thermosensitive Recording Layer>In forming a thermosensitive recording layer, a thermosensitive recording layer forming liquid is applied to a partial region of the top surface of the support to form the thermosensitive recording layer.

[0229] As used herein, "applying the thermosensitive recording layer forming liquid to the top surface" of the support means not only that the thermosensitive recording layer forming liquid is applied directly to one surface of the support, but also that the thermosensitive recording layer forming liquid may be applied to one surface of the support via another layer or member. For example, the thermosensitive recording layer forming liquid may be applied to the top surface of the color ink layer arranged on the support.

[0230] As used herein, applying the thermosensitive recording layer forming liquid to "a partial region" of the top surface of the support means applying the thermosensitive recording layer forming liquid so that the area to which the thermosensitive recording layer forming liquid is applied is less than 100% of the total area of the top surface of the support.

[0231] The method for forming the thermosensitive recording layer is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include a method for forming the thermosensitive recording layer by applying the thermosensitive recording layerforming liquid onto the support and drying the liquid.

[0232] The method for applying the thermosensitive recording layer forming liquid to a partial region of the top surface of the support is not particularly limited, and the layer can be formed by using a generally known printing method. In the method for manufacturing a thermosensitive recording medium according to the present disclosure, the thermosensitive recording layer and the color ink layer are formed in a partial region of the top surface of the support, so that the thermosensitive recording layer and the color ink layer can be formed simultaneously.

[0233] The printing method is not particularly limited, and any well-known printing method can be used. Among such well-known printing methods, gravure printing and flexographic printing are preferred. Generally, such printing methods are often used on paper or film substrates for packaging, and because a plurality of colors are required for printing, devices including print heads for 5 to 12 colors in one process are commonly used. Therefore, for example, a print head can be used to print several colors of color ink for design printing, and the remaining print heads can be used to print the thermosensitive recording layer forming liquid, and further a first protective part forming liquid or a second protective part forming liquid in one pass at the same time, and thus, better design position accuracy can be provided rather than production using two or more passes, and also productivity is significantly improved.

[0234] Such studies can be carried out more efficiently by combining laboratory-scale, pilot-scale, and actual equipment-scale studies. In the laboratory-scale study, for example, evaluation can be provided using a lab printing machine (PRINTABILITY TESTER manufactured by IGT, FLEXIPROOF manufactured by Matsuo Sangyo Co., Ltd.) or the like, but the evaluation machine is not limited to such a machine, and evaluation can be provided using any commonly available lab printing machine. In the pilot-scale study and the actual equipmentscale study, more practical evaluation can be provided by preparing various gravure rolls and flexographic plates according to the design and the deposition amount required for evaluation.

[0235] The deposition amount of the thermosensitive recording layer forming liquid after drying is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1 g / m2or more and 20 g / m2or less, and more preferably 2 g / m2or more and 10 g / m2or less.

[0236] «Thermosensitive Recording Layer Forming Liquid»The thermosensitive recording layer forming liquid contains an electron-donating compound, an electron-accepting compound, and a solvent, preferably further contains a surfactant and a binder resin, and may further optionally contain other components.

[0237] The electron-donating compound, the electron-accepting compound, the binder resin, andother components are as described above in the section titled as <Thermosensitive Recording Layer> of (Thermosensitive Recording Medium).

[0238] - Solvent - The solvent is not particularly limited and can be appropriately selected depending on the purpose. Examples of the solvent include, but are not limited to, water, aromatic solvents, ester solvents, ketone solvents, alcohol solvents, aliphatic hydrocarbons, glycol solvents, paraffin solvents, petroleum-based solvents containing naphthene as the main component and having an aromatic component of 1% or less, and mixed solvents thereof. Such solvents may be used alone or in combination of two or more types. Among such solvents, from the viewpoints of the solubility of the electron-accepting compound and reducing the environmental load, the solvent is suitably an alcohol solvent, an ester solvent, or a mixed solvent of water and an alcohol solvent. Aromatic solvents such as toluene have low solubility for electron-accepting compounds, but the use of such a solvent is restricted from the viewpoint of reducing the environmental load due to VOC emissions in the printing industry.

[0239] Examples of the alcohol solvent include, but are not limited to, methanol, ethanol, isopropyl alcohol, n-propyl alcohol, and butanol. Among such alcohol solvents, ethanol is particularly preferred.

[0240] Examples of the ester solvent include, but are not limited to, ethyl acetate, propyl acetate, isopropyl acetate, isobutyl acetate, butyl acetate, isoamyl acetate, amyl acetate, hexyl acetate, phenyl acetate, and benzyl acetate.

[0241] Examples of water include, but are not limited to, pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, and distilled water, and ultrapure water.

[0242] The content of the solvent in the thermosensitive recording layer forming liquid is not particularly limited and can be appropriately selected depending on the purpose.

[0243] - Surfactant - When the thermosensitive recording layer forming liquid contains a surfactant, the surface tension of the thermosensitive recording layer forming liquid can be adjusted, and the desired shape and structure can be obtained more precisely when the thermosensitive recording layer forming liquid is applied to a partial region of the top surface of the support.

[0244] The surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples of the surfactant include, but are not limited to, anionic surfactants, nonionic surfactants, amphoteric surfactants, and fluorine-based surfactants.Examples of the anionic surfactants include, but are not limited to, polyoxyethylene alkyl ether acetates, dodecylbenzene sulfonates, laurates, and polyoxyethylene alkyl ether sulfates. Such anionic surfactants may be used alone or in combination of two or more types.

[0246] Examples of the nonionic surfactants include, but are not limited to, acetylene glycol surfactants, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, and polyoxyethylene sorbitan fatty acid esters. Such nonionic surfactants may be used alone or in combination of two or more types.

[0247] Examples of the acetylene glycol surfactants include, but are not limited to, 2, 4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3,5-dimethyl-l-hexyne-3-diol, and 2,5,8,ll-tetramethyl-6-dodecyne-5,8-diol. Such acetylene glycol surfactants may be used alone or in combination of two or more types.

[0248] The content of the surfactant in the thermosensitive recording layer forming liquid is not particularly limited and can be appropriately selected depending on the purpose.

[0249] The method for preparing the thermosensitive recording layer forming liquid is not particularly limited, and any well-known method can be used. An example of the method includes a method including pulverizing and dispersing an electron-donating compound, an electron-accepting compound, and a solvent, optionally together with other components in a dispersing machine such as a ball mill, an attritor, or a sand mill until the desired dispersed particle size is reached.

[0250] The dispersed particle size of the thermosensitive recording layer forming liquid is not particularly limited, but is preferably 0.1 pm or more and 3 pm or less.

[0251] <Forming Color Ink Layer>In forming the color ink layer, color ink is applied to a partial region of the top surface of the support to form the color ink layer. There is no particular restriction on the order in forming the color ink layer and forming the thermosensitive recording layer.

[0252] As used herein, the "applying the color ink to the top surface" of the support means not only that the color ink is applied directly to one surface of the support, but also that the color ink may be applied to one surface of the support via another layer or member.

[0253] As used herein, applying the color ink to a "partial region" of the top surface of the support means applying the color ink so that the area to which the color ink is applied is less than 100% of the total area of the top surface of the support.

[0254] The method for forming the color ink layer is not particularly limited and may be appropriately selected depending on the purpose. An example of the method includes a method for forming the color ink layer by applying the color ink onto the support and drying such an applied layer.

[0255] The method for applying color ink to a partial region of the top surface of the support is not particularly limited, and the method similar to the method for applying the thermosensitive recording layer forming liquid to a partial region of the top surface of the support can be employed.

[0256] The deposition amount of color ink after drying is not particularly limited and can be appropriately selected depending on the purpose, but the average thickness of the color ink layer is preferably 0.05 g / m2or more and 10 g / m2or less, and more preferably 0.5 g / m2or more and 4.0 g / m2or less.

[0257] «Color Ink»The color ink contains a coloring material and a solvent, and preferably further contains a surfactant and a binder resin, and may further optionally contain other components.

[0258] The coloring material, the binder resin, and other components are as described above in the section titled as <Color Ink Layer> of (Thermosensitive Recording Medium). The solvent and the surfactant may be similar to those used in the thermosensitive recording layer forming liquid.

[0259] The color ink may be appropriately prepared by a well-known method, or commercially available products may be used.

[0260] <Forming First Protective Part>In forming the first protective part, the first protective part forming liquid is applied to at least a partial region of at least the top surface of the color ink layer to form the first protective part.

[0261] The forming the first protective part is performed after the forming the color ink layer.

[0262] As used herein, "applying the first protective part forming liquid to the top surface" of the color ink layer means not only that the first protective part forming liquid is directly applied to one surface of the color ink layer, but also that the first protective part forming liquid may be applied to one surface of the color ink layer via another layer or member.

[0263] The applying the first protective part forming liquid to "at least the top surface" of the color ink layer means that the first protective part forming liquid may be applied to a surface other than the top surface of the color ink layer, for example, a side surface. When the first protective part forming liquid is applied to the side surface of the color ink layer, the first protective part forming liquid applied to the top surface of the color ink layer and the first protective part forming liquid applied to the side surface of the color ink layer may be applied simultaneously or separately. When the first protective part on the top surface of the color ink layer and the first protective part on the side surface of the color ink layer are formed to be continuous, it is efficient to simultaneously apply the first protective part forming liquid to the top surface of the color ink layer and the first protective part forming liquid to the side surface of the color ink layer.

[0264] As used herein, the applying the first protective part forming liquid to "at least a partial region of "at least the top surface of the color ink layer may mean that the first protective part forming liquid may be applied so that the area to which the first protective part forming liquid is applied is less than 100% of the total area of the upper surface of the color ink layer (that is, the first protective part forming liquid may be applied to at least a partial region of the top surface of the color ink layer), the first protective part forming liquid may be applied so that the area to which the first protective part forming liquid is applied is 100% of the total area of the upper surface of the color ink layer (that is, the first protective part forming liquid may be applied to at least the entire top surface of the color ink layer), and the first protective part forming liquid may be applied so that the area to which the first protective part forming liquid is applied is more than 100% (that is, the first protective part forming liquid may be applied beyond the top surface of the color ink layer). However, it is preferable that the first protective part forming liquid is not applied beyond the top surface of the support. When the first protective part forming liquid is applied so that the area to which the first protective part forming liquid is applied is less than 100% of the total area of the top surface of the color ink layer, it is preferable to apply a forming liquid of another layer or member to the top surface of the color ink layer to which the first protective part forming liquid is not applied.

[0265] The method for forming the first protective part is not particularly limited and can be appropriately selected depending on the purpose. An example of the method may include a method for forming the first protective part by applying the first protective part forming liquid onto the support and drying the first protective part forming liquid.

[0266] The method for applying the first protective part forming liquid to at least a partial region of at least the top surface of the color ink layer is not particularly limited, and a method similar to the method for applying the thermosensitive recording layer forming liquid to a partial region of the top surface of the support can be used.

[0267] The deposition amount of the first protective part forming liquid after drying the first protective part forming liquid is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.1 g / m2or more and 10 g / m2or less, and more preferably 0.5 g / m2or more and 3.0 g / m2or less.

[0268] <Forming Second Protective Part>In forming the second protective part, a second protective part forming liquid is applied to at least the top surface of the thermosensitive recording layer to form the second protective part.

[0269] The forming the second protective part is performed after the forming the thermosensitive recording layer.

[0270] As used herein, the "applying the second protective part forming liquid to the top surface" of the thermosensitive recording layer means not only that the second protective part forming liquid is applied directly to one surface of the thermosensitive recording layer, but also that the second protective part forming liquid may be applied to one surface of the thermosensitive recording layer via another layer or member. For example, when the first protective part is formed on at least the top surface of the thermosensitive recording layer, the second protective part forming liquid may be applied to at least a partial region of the top surface of the first protective part. In such a case, the second protective part is formed in at least a partial region of at least the top surface of the first protective part, and in a region facing at least a part of the thermosensitive recording layer.

[0271] The applying the second protective part forming liquid to "at least the top surface" of the thermosensitive recording layer means that the second protective part forming liquid may be applied to a surface other than the top surface of the thermosensitive recording layer, for example, a side surface. When the second protective part forming liquid is applied to the side surface of the thermosensitive recording layer, the second protective part forming liquid applied to the top surface of the thermosensitive recording layer and the second protective part forming liquid applied to the side surface of the thermosensitive recording layer may be applied simultaneously or separately. When the second protective part on the top surface of the thermosensitive recording layer and the second protective part on the side surface of the thermosensitive recording layer are formed to be continuous, it is efficient to simultaneously apply the second protective part forming liquid to the top surface of the thermosensitive recording layer and the second protective part forming liquid to the side surface of the thermosensitive recording layer.

[0272] As used herein, the applying the second protective part forming liquid to "at least the top surface" of the thermosensitive recording layer means that the second protective part forming liquid may be applied so that the area to which the second protective part forming liquid isapplied is 100% of the total area of the top surface of the thermosensitive recording layer (that is, the second protective part forming liquid is applied to the entire surface of at least the top surface of the thermosensitive recording layer), or that the second protective part forming liquid may be applied so that the area to which the second protective part forming liquid is applied is more than 100% of the total area of the top surface of the thermosensitive recording layer (that is, the second protective part forming liquid is applied beyond the top surface of the thermosensitive recording layer). However, it is preferable that the second protective part forming liquid is not applied beyond the top surface of the support.

[0273] The method for forming the second protective part is not particularly limited and can be appropriately selected depending on the purpose. An example of the method may include a method of forming the second protective part by applying the second protective part forming liquid onto the support and drying the second protective part forming liquid.

[0274] The method for applying the second protective part forming liquid to at least the top surface of the thermosensitive recording layer is not particularly limited, and the method similar to the method for applying the thermosensitive recording layer forming liquid to a partial region of the top surface of the support can be used.

[0275] The deposition amount of the second protective part forming liquid after drying the second protective part forming liquid is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.1 g / m2or more and 10 g / m2or less, and more preferably 0.5 g / m2or more and 3.0 g / m2or less.

[0276] «First Protective Part Forming Liquid and Second Protective Part Forming Liquid» The composition of the first protective part forming liquid and the composition of the second protective part forming liquid may be the same as or different from each other. The first protective part forming liquid and the second protective part forming liquid contain a binder resin and a solvent, and preferably further contain a crosslinking agent, a pigment (filler), a wax, and the like, and may further optionally contain other components.

[0277] The first protective part forming liquid preferably contains at least a binder resin, a solvent, and a crosslinking agent, and more preferably further contains a pigment (filler), and a wax.

[0278] The second protective part forming liquid preferably contains a binder resin, a solvent, a crosslinking agent, a pigment (filler), and a wax.

[0279] The binder resin, the crosslinking agent, and other components are as described above in the section titled as <First Protective Part> or <Second Protective Part> of (Thermosensitive Recording Medium). The solvent may be similar to that used in the thermosensitive recordinglayer forming liquid.

[0280] The method for preparing the first protective part forming liquid and the second protective part forming liquid is not particularly limited, and any well-known method can be used. An example of the method may include a method in which a binder resin, a solvent, and further other components are optionally mixed.

[0281] When at least one of the first protective part forming liquid and the second protective part forming liquid contains a wax, it is preferable to use a dispersion obtained by wet dispersion using a dispersant to disperse the wax.

[0282] The dispersion is not particularly limited and can be appropriately selected depending on the purpose. Examples of the dispersion include, but are not limited to, (i) an aqueous dispersion in which a wax, preferably an oxidized polyethylene wax, is dispersed in water using polyvinyl alcohol serving as a dispersant, and (ii) an emulsion in which a wax, preferably an oxidized polyethylene wax, is emulsified and dispersed using an anionic emulsifier.

[0283] <Other Processes>Other processes in the method for manufacturing a thermosensitive recording medium according to the present disclosure are not particularly limited, and an example of the other processes includes, but is not limited to, a process for forming other layers in the thermosensitive recording medium, such as a back layer, an under layer, a heat seal layer, a release layer, and an adhesive layer.

[0284] The method for forming such other layers is not particularly limited, and an example of the method includes a method in which a layer-forming liquid in which the constituent materials of each layer are mixed is applied and laminated in the same manner as the method for applying the thermosensitive recording layer-forming liquid, the color ink, and the like.

[0285] (Image Recording Method)An image recording method according to the present disclosure includes recording an image on the thermosensitive recording medium according to the present disclosure using the thermal head. A CO2 laser, a semiconductor laser, or the like can also be used in a method for recording the image on the thermosensitive recording medium according to the present disclosure.[Examples]

[0286] The present disclosure will be specifically described below with reference to Preparation Examples, Examples, and Comparative Examples, but the present disclosure is not limited to such Preparation Examples, Examples, and Comparative Examples at all.

[0287] (Preparation Example 1)Preparation of Thermosensitive Recording Layer Forming Liquid>A thermosensitive recording layer forming liquid 1 was prepared by dispersing 6.2 parts by mass of a black dye (ODB2, manufactured by Yamamoto Chemical Industry Co., Ltd.) as an electron-donating compound, 18.7 parts by mass of N,N'-di-[3-(p-toluenesulfonyloxy)phenyl] urea represented by the following structural formula (1) as an electron-accepting compound, 40.0 parts by mass of an acrylic resin (A-1125, manufactured by DSM, solid content: 19.5% by mass in water solvent), 4.6 parts by mass of a styrene-acrylic resin (Joncryl PDX-7741, manufactured by BASF, solid content: 41.5% by mass in water solvent), 1.9 parts by mass of a surfactant (PD-001, manufactured by Nissin Chemical Industry Co., Ltd., solid content: 10% by mass), 15 parts by mass of water, and 13.6 parts by mass of ethanol using a sand mill.[Chem. 1]Chemical formula 0)

[0288] (Preparation Example 2)Preparation of Protective Part Forming Liquid 1>100 parts by mass of an acrylic resin (A-1125, manufactured by DSM, solid content: 19.5% by mass in water solvent solution), 20 parts by mass of an oxazoline derivative serving as a crosslinking agent (Epocross WS-500, manufactured by Nippon Shokubai, solid content: 39% by mass), and 50 parts by mass of ethanol were mixed and stirred to prepare a protective part forming liquid 1.

[0289] (Preparation Example 2)Preparation of Protective Part Forming Liquid 2>- Preparation of Pigment Dispersion - 84.2 parts by mass of calcium carbonate as a pigment, 20.2 parts by mass of a styrene-acrylic resin (manufactured by BASF, JONCRYL PDX-7741, solid content: 41.5% by mass), 0.4 parts by mass of surfactant (manufactured by Nissin Chemical Industry Co., Ltd., PD-001, solid content: 10% by mass), 51.1 parts by mass of water, 51.1 parts by mass of ethanol were dispersed using a sand mill so that the 50% cumulative volume particle size (D50) measured with a laser diffraction / scattering particle size distribution analyzer (device name: LA-960, manufactured by HORIBA, Ltd.) was 0.2 pm, and as a result, a pigment dispersion (solid content: 45% by mass, ethanol ratio in the solvent 44.8% by mass) was obtained.

[0290] A protective part forming liquid 2 was prepared by mixing and stirring 20.7 parts by mass of the pigment dispersion, 47.7 parts by mass of an acrylic resin (A-1125, manufactured byDSM, solid content: 19.5% by mass in water solvent), 9.5 parts by mass of an oxazoline derivative serving as a crosslinking agent, 4.7 parts by mass of an oxidized polyethylene wax, 5 parts by mass of water, and 40 parts by mass of ethanol.

[0291] (Example 1)Preparation of Thermosensitive Recording Medium>In Example 1, the thermosensitive recording medium 100 illustrated in FIG. 2 A and FIG. 2B was prepared by the following method.

[0292] - Formation of Thermosensitive Recording Layer 2 - The thermosensitive recording layer forming liquid obtained in Preparation Example 1 was gravure printed onto a partial region of one surface (upper surface 1 A) of a polyethylene terephthalate (PET) film (product name: E5102, average thickness: 12 pm, manufactured by Toyobo Co., Ltd., haze: 2.3%) serving as a support 1 as follows, so that the deposition amount after drying the thermosensitive recording layer forming liquid would be 4 g / m2, and then dried, to form the thermosensitive recording layer 2 as illustrated in FIG. 2 A and FIG. 2B.

[0293] —Gravure Printing- Using a small gravure printing tester manufactured by Chiba Machinery Co., Ltd., a gravure roll having an outer diameter of 200 mm was set, and gravure printing was performed under conditions of a line speed of 40 m / min and a drying temperature setting of 70°C to obtain the layout illustrated in FIG. 2A and FIG. 2B, followed by drying.

[0294] - Formation of Color Ink Layer 3 - On the top surface 1A of the polyethylene terephthalate film (product name: E5102) serving as the support 1, on which the thermosensitive recording layer 2 was formed, gravure printing was performed with a gravure printing ink (product name: Finart R794 White, manufactured by DIC Graphics Corporation) in a partial region different from the region on which the thermosensitive recording layer 2 was formed, in the same manner as in the formation of the thermosensitive recording layer 2, so that the deposition amount after drying was 1 g / m2, followed by drying to form the color ink layer 3 as illustrated in FIG. 2A and FIG. 2B. It is noted that a partial region where the color ink layer 3 was formed and which was different from the region where the thermosensitive recording layer 2 was formed was a region where the thermosensitive recording layer 2 and the color ink layer 3 did not come into contact with each other, and also a region where the first protective part 4 and the second protective part 5 described later did not come into contact with each other (were not arranged continuously).

[0295] - Formation of First Protective Part 4 - The protective part forming liquid 1 was gravure printed on the top surface and the side surfaces of the color ink layer 3 in the same manner as in the formation of the thermosensitiverecording layer 2 so that the deposition amount after drying was 2 g / m2, and then dried to form the first protective part 4 as illustrated in FIG. 2 A and FIG. 2B.

[0296] - Formation of Second Protective Part 5 - The protective part forming liquid 2 was gravure printed on the top surface and the side surfaces of the thermosensitive recording layer 2 in the same manner as in the formation of the thermosensitive recording layer 2 so that the deposition amount after drying was 2 g / m2, and then dried to form the second protective part 5 as illustrated in FIG. 2 A and FIG. 2B.

[0297] (Example 2)Preparation of Thermosensitive Recording Medium>In Example 2, the thermosensitive recording medium 100 illustrated in FIG. 4 A and FIG. 4B was prepared by the following method.

[0298] - Formation of Color Ink Layer 3 - Gravure printing was performed with a gravure printing ink (trade name: Finart R794 White, manufactured by DIC Graphics Corporation) in a partial region of one surface (top surface 1A) of a polyethylene terephthalate (PET) film (product name: E5102, average thickness: 12 pm, manufactured by Toyobo Co., Ltd., haze: 2.3%) serving as the support 1 in the same manner as in Example 1, so that the deposition amount after drying would be 1 g / m2, followed by drying to form the color ink layer 3 as illustrated in FIG. 4 A and FIG. 4B.

[0299] - Formation of Thermosensitive Recording Layer 2 - The thermosensitive recording layer forming liquid obtained in Preparation Example 1 was gravure printed in a partial region of the top surface of the color ink layer 3 in the same manner as in Example 1 so that the deposition amount was 4 g / m2after drying the thermosensitive recording layer forming liquid, and then dried to form the thermosensitive recording layer 2 as illustrated in FIG. 4 A and FIG. 4B.

[0300] - Formation of Second Protective Part 5 - On the top surface of the color ink layer 3, the protective part forming liquid 2 was gravure printed in the same manner as in the formation of the thermosensitive recording layer in a region other than the region where the thermosensitive recording layer 2 was placed, the side surfaces of the color ink layer 3, and the top surface and the side surfaces of the thermosensitive recording layer 2 so that the deposition amount after drying the protective part forming liquid 2 was 2 g / m2, and then dried to form the first protective part 4 and the second protective part 5 as illustrated in FIG 4 A and FIG. 4B.

[0301] (Example 3)Preparation of Thermosensitive Recording Medium>In Example 3, the thermosensitive recording medium 100 illustrated in FIG. 2 A and FIG. 2B was prepared in the same manner as in Example 1, except that the first protective part 4 was formed by using the protective part forming liquid 2 instead of the protective part forming liquid 1 in Example 1.

[0302] (Comparative Example 1)Preparation of Thermosensitive Recording Medium>In Comparative Example 1, a thermosensitive recording medium 200 illustrated in FIG. 14A and FIG. 14B was prepared in the same manner as in Example 1, except that the first protective part 4 was not formed and the first protective part 4 was not formed on the color ink layer 3.

[0303] [Evaluation]The thermosensitive recording media of Examples 1 to 3 and Comparative Example 1 were printed to develop colors using a thermal printer (model name: DF6530, manufactured by VIDEO JET) at a printing speed of 150 mm / s, printing energy of 100%, and head pressure of 3.5 kg. The obtained images were visually inspected by a specialist evaluator for releasing of the color ink layer, accumulation of ink residue on the thermal head, and printing defect of the thermosensitive recording layer, and were evaluated according to the following evaluation criteria. The results are presented in Table 1 below.

[0304] - Evaluation Criteria for Abrasion Resistance - A: No release of the color ink layer is observed, and the design remains the same as the original.B: Release of the color ink layer is observed, damaging the original design.

[0305] - Accumulation of Ink Residue on Thermal Head - A: No accumulation of ink residue is observed on the thermal head.B: Accumulation of ink residue is observed on the thermal head.

[0306] - Evaluation Criteria for Printing Defects - A: No printing defects are observed in the colored portion of the thermosensitive recording layer.B: Printing defects are observed in the colored portion of the thermosensitive recording layer.

[0307] [Table 1]Evaluation ResultScratch Deposition of Ink Residue PrintingNature on Thermal Head DefectExample 1 A A AExample 2 A A AExample 3 A A AComparativeB B BExample 1

[0308] From the results in Table 1, it was found that the thermosensitive recording media of Examples 1 to 3, compared to the thermosensitive recording medium of Comparative Example 1, could prevent scratches on the color ink layer caused by contact between the thermal head and the color ink layer in printing with the thermal head, as a result of which can provide a film with excellent visual design, and that even when ink residue from the color ink layer scraped off by abrasion by the thermal head accumulates on the thermal head, printing defects caused by the ink residue and scratches on the support surface caused by the ink residue in printing with the thermal head can be prevented.

[0309] Aspects of the present disclosure include the following aspects, for example.Aspect 1.A thermosensitive recording medium includinga support,a thermosensitive recording layer arranged in a partial region of a top surface of the support,a color ink layer arranged in a partial region of the top surface of the support, a first protective part arranged in at least a partial region of at least a top surface of the color ink layer, anda second protective part arranged on at least a top surface of the thermosensitive recording layer.Aspect 2.The thermosensitive recording medium according to Aspect 1, in which the first protective part or the second protective part is arranged on a side surface of the color ink layer.Aspect 3.The thermosensitive recording medium according to Aspect 1 or Aspect 2, wherein the firstprotective part or the second protective part is arranged on a side surface of the thermosensitive recording layer.Aspect 4.The thermosensitive recording medium according to any one of Aspect 1 to Aspect 3, in which the partial region of the top surface of the support in which the color ink layer is arranged is different from the partial region of the top surface of the support in which the thermosensitive recording layer is arranged.Aspect 5.The thermosensitive recording medium according to any one of Aspect 1 to Aspect 3, in which the thermosensitive recording layer is arranged in a partial region of the top surface of the color ink layer.Aspect 6.The thermosensitive recording medium according to Aspect 5, in which the first protective part is arranged on at least the top surface of the thermosensitive recording layer, and the second protective part is arranged in at least a partial region of at least a top surface of the first protective part, which faces at least a part of the thermosensitive recording layer.Aspect 7.The thermosensitive recording medium according to any one of Aspect 1 to Aspect 6, in which a composition of a material of the first protective part is the same as a composition of a material of the second protective part.Aspect 8.The thermosensitive recording medium according to any one of Aspect 1 to Aspect 7, in which the first protective part and the second protective part are arranged continuously.Aspect 9.The thermosensitive recording medium according to any one of Aspect 1 to Aspect 8, in which the first protective part is free of an ultraviolet-curable resin.Aspect 10.The thermosensitive recording medium according to any one of Aspect 1 to Aspect 9, in which a haze of the support is 5% or less.Aspect 11.The thermosensitive recording medium according to any one of Aspect 1 to Aspect 10, in which a haze of the first protective part is 10% or less.Aspect 12.The thermosensitive recording medium according to any one of Aspect 1 to Aspect 11, in which the second protective part includes a wax and a pigment.Aspect 13.An image recording method including recording an image on the thermosensitive recording medium according to any one of Aspect 1 to Aspect 12 using a thermal head.Aspect 14.A method for manufacturing a thermosensitive recording medium, includingapplying a thermosensitive recording layer forming liquid to a partial region of a top surface of a support to form a thermosensitive recording layer,applying color ink to a partial region of the top surface of the support to form a color ink layer,applying a first protective part forming liquid to at least a partial region of at least a top surface of the color ink layer to form a first protective part, andapplying a second protective part forming liquid to at least a top surface of the thermosensitive recording layer to form a second protective part.

[0310] With the thermosensitive recording medium according to any one of Aspect 1 to Aspect 12, the image recording method according to Aspect 13, and the method for manufacturing a thermosensitive recording medium according to Aspect 14, it is possible to solve the above-mentioned conventional problems and achieve the object of the present disclosure.

[0311] The above-described embodiments are illustrative and do not limit the present invention. Thus, numerous additional modifications and variations are possible in light of the above teachings. For example, elements and / or features of different illustrative embodiments may be combined with each other and / or substituted for each other within the scope of the present invention. Any one of the above-described operations may be performed in various other ways, for example, in an order different from the one described above.

[0312] This patent application is based on and claims priority to Japanese Patent Application No. 2024-186147, filed on October 22, 2024, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein.[Reference Signs List]

[0313] 1 ... Support1A ... Top surface of supportIB ... Bottom surface of support2 ... Thermosensitive recording layer3 ... Color ink layer4 ... First protective part5 ... Second protective part100 ... Thermosensitive recording medium200 ... Thermosensitive recording medium

Claims

1. [CLAIMS]1. A thermosensitive recording medium, comprising:3.a support;4.a thermosensitive recording layer arranged in a partial region of a top surface of the support;5.a color ink layer arranged in a partial region of the top surface of the support; a first protective part arranged in at least a partial region of at least a top surface of the color ink layer; and6.a second protective part arranged on at least a top surface of the thermosensitive recording layer.

2. The thermosensitive recording medium according to claim 1, wherein the first protective part or the second protective part is arranged on a side surface of the color ink layer.

3. The thermosensitive recording medium according to claim 1 or 2, wherein the first protective part or the second protective part is arranged on a side surface of the thermosensitive recording layer.

4. The thermosensitive recording medium according to any one of claims 1 to 3, wherein the partial region of the top surface of the support in which the color ink layer is arranged is different from the partial region of the top surface of the support in which the thermosensitive recording layer is arranged.

5. The thermosensitive recording medium according to any one of claims 1 to 3, wherein the thermosensitive recording layer is arranged in a partial region of the top surface of the color ink layer.

6. The thermosensitive recording medium according to claim 5, wherein12.the first protective part is arranged on at least the top surface of the thermosensitive recording layer, and13.the second protective part is arranged in at least a partial region of at least a top surface of the first protective part, which faces at least a part of the thermosensitive recording layer.

7. The thermosensitive recording medium according to any one of claims 1 to 6, wherein a composition of a material of the first protective part is the same as a composition of a material of the second protective part.

8. The thermosensitive recording medium according to any one of claims 1 to 7,wherein the first protective part and the second protective part are arranged continuously.

9. The thermosensitive recording medium according to any one of claims 1 to 8, wherein the first protective part is free of an ultraviolet-curable resin.

10. The thermosensitive recording medium according to any one of claims 1 to 9, wherein a haze of the support is 5% or less.

11. The thermosensitive recording medium according to any one of claims 1 to 10, wherein a haze of the first protective part is 10% or less.

12. The thermosensitive recording medium according to any one of claims 1 to 11, wherein the second protective part includes a wax and a pigment.

13. An image recording method, comprising:21.recording an image on the thermosensitive recording medium according to any one of claims 1 to 12 using a thermal head.

Images