JP2023144410A - Thermal recording medium - Google Patents

Abstract

To provide a thermal recording medium that can reduce the wear of a thermal head and has excellent sticking resistance.SOLUTION: A thermal recording medium includes a substrate 2, on which laminated are at least a thermal recording layer 4 and a protective layer 6 to be the uppermost layer. The surface of the protective layer 6 is provided with recesses, which are evaporation holes from moisture or cracks, which do not reach the thermal recording layer 4.SELECTED DRAWING: Figure 1

Description

The present invention relates to a heat-sensitive recording material in which at least a heat-sensitive recording layer and a protective layer serving as an uppermost layer are laminated on a base material.

2. Description of the Related Art Thermosensitive recording materials, such as thermal paper in which a thermosensitive recording layer is formed on a paper base material, are used in various applications such as receipt paper, facsimile paper, and labels.

Some such thermal papers contain elastic particles in the uppermost layer, which is the outermost surface of the thermal paper, as disclosed in Patent Document 1, for example, in order to reduce wear on the thermal head of a printer.

JP 2017-52193 Publication

In the thermal paper of Patent Document 1, it is necessary to mix elastic particles into the material constituting the top layer, and the heat generated by the top layer melts due to the heat of the printer's thermal head and adheres to the thermal head. It is difficult to sufficiently prevent the sticking phenomenon.

The present invention has been made in view of these circumstances, and it is not necessary to incorporate elastic particles or the like into the constituent material of the uppermost layer, which reduces wear on the thermal head and provides good sticking resistance. The purpose is to provide a thermosensitive recording medium.

In order to achieve the above object, the present invention is configured as follows.

(1) The heat-sensitive recording material according to the present invention is a heat-sensitive recording material in which at least a heat-sensitive recording layer and a protective layer serving as an uppermost layer are laminated on a base material, and the surface of the protective layer has the heat-sensitive A recessed portion that does not reach the recording layer is formed.

According to the thermal recording material according to the present invention, since the recessed portion is formed on the surface of the protective layer, which is the uppermost layer, the contact area between the protective layer and the thermal head can be reduced, and the contact area between the protective layer and the thermal head can be reduced. Abrasion is suppressed and sticking resistance is improved.

Furthermore, since the recesses on the surface of the protective layer do not reach the heat-sensitive recording layer, even if oil or the like adheres to the surface of the protective layer, it will not reach the heat-sensitive recording layer, and the heat-sensitive recording layer will not be discolored. , print storage stability is good.

(2) The heat-sensitive recording material according to the present invention is a heat-sensitive recording material in which at least a heat-sensitive recording layer and a protective layer serving as an uppermost layer are laminated on a base material, and the protective layer is made of hydrophobic resin particles. It consists of

According to the heat-sensitive recording material of the present invention, the uppermost protective layer composed of hydrophobic resin particles is formed by applying a coating liquid in which hydrophobic resin particles are dispersed and drying it. The resin particles aggregate and contract, creating cracks that form recesses on the surface of the protective layer. The cracks formed on the surface of the protective layer can reduce the contact area between the protective layer and the thermal head, suppress wear of the thermal head, and improve sticking resistance.

(3) In a preferred embodiment of the present invention, the recess is at least one of a moisture evaporation hole and a crack.

According to this embodiment, when a coating liquid for forming a protective layer is applied and dried, evaporation holes caused by evaporation of water and cracks caused by shrinkage become concave portions on the surface of the protective layer.

(4) In one embodiment of the present invention, the protective layer does not contain a water-soluble polymer.

Coating liquids containing water-soluble polymers are difficult to aggregate and form a film when being applied and dried, so no cracks occur. According to this embodiment, the protective layer does not contain water-soluble polymers. Therefore, cracks can be reliably generated on the surface of the protective layer.

(5) In another embodiment of the present invention, an intermediate layer is formed between the protective layer and the heat-sensitive recording layer.

According to this embodiment, since an intermediate layer is formed between the uppermost protective layer and the heat-sensitive recording layer, even if there are moisture evaporation holes or cracks on the surface of the protective layer, the surface of the protective layer Since oil and the like adhering to the recording layer are blocked by the intermediate layer and do not reach the heat-sensitive recording layer, print storage stability is good.

(6) In yet another embodiment of the present invention, an undercoat layer containing hollow particles is formed between the base material and the heat-sensitive recording layer.

According to this embodiment, the undercoat layer containing hollow particles can function as a heat insulating layer that prevents the dissipation of heat applied from the thermal head and as an elastic layer that has cushioning properties. will improve.

According to the present invention, since the recesses are formed on the surface of the protective layer, which is the uppermost layer, the contact area between the protective layer and the thermal head can be reduced, and wear of the thermal head can be suppressed. , the sticking resistance is improved.

Furthermore, since the recesses on the surface of the protective layer do not reach the heat-sensitive recording layer, print storage stability is good.

FIG. 1 is a schematic cross-sectional view of a heat-sensitive recording medium according to an embodiment of the present invention. FIG. 2 is an electron microscope (SEM) photograph of the surface of the protective layer of the heat-sensitive recording material according to one embodiment of the present invention. FIG. 3 is an electron microscope (SEM) photograph of the surface of the protective layer of a heat-sensitive recording material as a comparative example. FIG. 4 is an enlarged electron microscope (SEM) photograph showing cracks on the surface of the protective layer shown in FIG. FIG. 5 is an electron microscope (SEM) photograph showing a further enlarged portion of FIG. 4 other than the crack portion. FIG. 6 is an electron microscope (SEM) photograph of the surface of a protective layer having many evaporation holes and few cracks. FIG. 7 is an electron microscope (SEM) photograph of the surface of a protective layer having only a large number of evaporation holes.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of a heat-sensitive recording medium according to an embodiment of the present invention.

The heat-sensitive recording material 1 has a sheet-like base material 2 over which at least a heat-sensitive recording layer 4 that develops color when heated and a protective layer serving as the uppermost layer are laminated. In this embodiment, the heat-sensitive recording layer 4 An intermediate layer 5 is formed between the substrate 2 and the protective layer 6, and an undercoat layer 3 is formed between the base material 2 and the heat-sensitive recording layer 4, forming a laminated structure.

The base material 2 is, for example, paper, nonwoven fabric, plastic film, metal foil, or a composite sheet made of a combination of these. In this embodiment, paper is used as the base material 2.

Undercoat layer 3 contains hollow particles and a binder.

The average particle diameter of the hollow particles is preferably 1 μm to 100 μm. Within this range, an undercoat layer with excellent heat insulation properties can be formed. The average particle diameter is a weight average particle diameter measured by laser diffraction method. The average particle diameter can be measured by laser diffraction using Microtrac Bell's product name "MT3300EX-II".

The hollowness ratio of the hollow particles is preferably 30% to 70%. Within this range, an undercoat layer with excellent heat insulation properties can be formed, and a heat-sensitive recording material with excellent printing quality can be provided.

The hollow ratio is calculated using the following formula.

Hollowness ratio = {(volume of voids)/(volume of hollow particles)}×100
The content of the hollow particles is preferably 40 parts by weight to 90 parts by weight based on 100 parts by weight of the undercoat layer.

The coating amount (dry weight) of the undercoat layer 3 is preferably 1 g/m ² to 10 g/m ² .

The thickness of the undercoat layer 3 is preferably 1 μm to 20 μm.

The hollow particles are made of, for example, thermoplastic resin. Examples of materials constituting the hollow particles include polystyrene resins, polyvinyl chloride resins, polyvinylidene chloride resins, polyvinyl acetate resins, polyacrylic acid ester resins, polyacrylonitrile resins, polybutadiene resins, etc. Can be mentioned.

Examples of the binder contained in the undercoat layer 3 include acrylic-styrene copolymer, styrene-butadiene copolymer, acrylic-butadiene-styrene copolymer, vinyl acetate resin, and vinyl acetate-acrylic acid copolymer. , styrene-acrylic ester copolymer, acrylic ester resin, polyurethane resin, and the like.

In addition, as a binder, polyvinyl alcohol; starch and its derivatives; cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose; sodium polyacrylate; polyvinylpyrrolidone; acrylamide-acrylic acid ester copolymer; acrylamide -Acrylic acid ester-methacrylic acid terpolymer; Styrene-maleic anhydride copolymer alkali salt; Isobutylene-maleic anhydride copolymer alkali salt; Polyacrylamide; Sodium alginate; Gelatin; Water-soluble polymers such as casein may also be used.

The heat-sensitive recording layer 4 contains a coloring agent, a color developer, etc. that develops color when heated. The heat-sensitive recording layer 4 further contains a binder, a sensitizer, a lubricant, a filler, etc., as necessary.

As the coloring agent that develops color upon heating, commonly used leuco dyes can be used. Examples of the leuco dye include 3-(N-isobutyl-N-ethyl)amino-6-methyl-7-anilinofluorane, 3-(N-isopentyl-N-ethyl)amino-6-methyl- 7-o-chloroanilinofluorane, 3-(N-ethyl-N-p-toluidino)-6-methyl-7-anilinofluorane, 3-(N-ethyl-N-isopentyl)amino-6- Methyl-7-anilinofluorane, 3-(N-ethoxypropyl-N-ethyl)amino-6-methyl-7-anilinofluorane, 3-(N-cyclohexyl-N-methyl)amino-6-methyl -7-anilinofluorane, 3-(N-methyl-Nn-propyl)amino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-p-toluidinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-8-methylfluorane, 3-diethylamino -7-(m-trifluoromethylanilino)fluoran, 3-diethylamino-7-(o-chloroanilino)fluoran, 3-diethylamino-7-chlorofluoran, 3-dibutylamino-6-methyl-7-bromoflu Orane, 3-dibutylamino-7-(o-chloroanilino)fluorane, 3-dipentylamino-6-methyl-7-anilinofluorane, 3-dimethylamino-5-methyl-7-methylfluorane, 3-pyrrolidino -6-Methyl-7-anilinofluorane, crystal violet lactone, etc. can be used alone or in combination of two or more.

As the color developer, various electron-accepting substances that react with the above-mentioned leuco dyes when heated to develop color can be used. Examples of the color developer include 1,1-bis(p-hydroxyphenyl)cyclohexane, 1,1-bis(p-hydroxyphenyl)propane, 2,2-bis(p-hydroxyphenyl)propane, 2, 2-bis(p-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 2,2'-methylenebis(4-chlorophenol), 2,2-bis(4-hydroxy phenyl)-4-methylpentane, 2,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfone, 4-hydroxy-4'-n-propoxydiphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone , 4-hydroxy-4'-methyldiphenylsulfone, 4-hydroxyphenyl-4'-benzyloxyphenylsulfone, 4-hydroxy-4'-allyloxydiphenylsulfone, bis(3-allyl-4-hydroxyphenyl)sulfone, Poly(4-hydroxybenzoic acid), benzyl 4-hydroxybenzoate, 2,4-bis(phenylsulfonyl)phenol, α-{4-[(4-hydroxyphenyl)sulfonyl]phenyl}-ω-hydroxypoly(polymerization) degree n=1 to 7) (oxyethyleneoxyethyleneoxy-p-phenylenesulfonyl-p-phenylene)2,2-bis[(4-methyl-3-phenoxycarbonylaminophenyl)urea]diphenylsulfone, 3,5- Bis(α-methylbenzyl)salicylic acid, bis[4-(n-octyloxycarbonylamino)zinc salicylate], 4,4'-bis(p-tolylsulfonylaminocarbonylamino)diphenylmethane, 4-hydroxybenzenesulfonanilide, 2 '-(3-Phenylureido)benzenesulfonanilide, N-(2-hydroxyphenyl)-2-[(4-hydroxyphenyl)thio]acetamide, N-(4-hydroxyphenyl)-2-[(4-hydroxy phenyl)thio]acetamide, 4-[[4-[4-[4-[[4-(1-methylethoxy)phenyl]sulfonylphenoxy]butoxy]phenyl]sulfonyl]phenol, 4-tert-butylphenol formaldehyde polycondensation N-(p-toluenesulfonyl)N'-(3-p-toluenesulfonyloxyphenyl)urea, 1-phenyl-3-(4-methylphenylsulfonyl)urea, and the like can be used.

Examples of the binder contained in the heat-sensitive recording layer 4 include polyvinyl alcohol, modified polyvinyl alcohol, starch, casein, gelatin, polyamide, polyacrylamide, modified polyacrylamide, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, hydroxypropylcellulose, and polyvinylalcohol. Vinyl acetate, polyacrylic acid ester, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, diisobutylene-maleic anhydride copolymer, vinyl acetate-maleic anhydride copolymer, methyl vinyl anhydride Maleic acid copolymer, isopropylene-maleic anhydride copolymer, styrene-butadiene copolymer, polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinyl acetate copolymer, polyurethane, polystyrene, polyvinylpyrrolidone, acrylic ester , acrylonitrile, and methyl vinyl ether can be used alone or in combination of two or more.

Examples of the sensitizer include stearic acid, stearamide, stearanilide, methylolstearamide, methylenebisstearamide, ethylenebisstearamide, 1-benzyloxynaphthalene, 2-benzyloxynaphthalene, 2, 6-diisopropylnaphthalene, 1,2-diphenoxyethane, 1,2-diphenoxymethylbenzene, 1,2-bis(3,4-dimethylphenol)ethane, 1,2-bis(3-methylphenoxy)ethane , 1,2-bis(4-methylphenoxy)ethane, di(p-chlorobenzyl) oxalate, di(p-methylbenzyl) oxalate, dibenzyl oxalate, p-benzylbiphenyl, m-terphenyl, diphenylsulfone , benzyl p-benzyloxybenzoate, dibenzyl terephthalate, p-toluenesulfonamide, and the like, which are solid at room temperature and preferably have a melting point of about 70° C. or higher, can be used.

Examples of lubricants include fatty acids such as paraffin wax and oleic acid; polyolefin waxes such as polyethylene wax; metal soaps such as zinc stearate; ester waxes such as carnauba wax; oils such as silicone oil and whale oil. They can be used alone or in combination of two or more.

Examples of fillers include aluminum hydroxide, magnesium hydroxide, aluminum oxide, magnesium oxide, aluminum silicate, calcium carbonate, magnesium carbonate, titanium oxide, barium sulfate, silica gel, activated clay, talc, clay, kaolin, calcined kaolin. , diatomaceous earth, white carbon, zinc oxide, silicon oxide, colloidal silica, polystyrene resin particles, urea-formalin resin particles, polyolefin resin particles, etc. can be used alone or in combination of two or more.

In this embodiment, the heat-sensitive recording layer 4 is simultaneously coated in three layers together with the intermediate layer 5 and the protective layer 6 using a curtain coater.

By providing the intermediate layer 5 on the heat-sensitive recording layer 4, it is possible to obtain a heat-sensitive recording material 1 having excellent water resistance, chemical resistance, plasticizer resistance, and the like.

Examples of materials constituting the intermediate layer 5 include polyvinyl alcohol, modified polyvinyl alcohol, starch, modified starch, casein, gelatin, glue, gum arabic, polyamide, polyacrylamide, modified polyacrylamide, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, Hydroxypropyl cellulose, polyvinyl acetate, polyacrylic ester, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, diisobutylene-maleic anhydride copolymer, vinyl acetate-maleic anhydride copolymer , methyl vinyl-maleic anhydride copolymer, isopropylene-maleic anhydride copolymer, styrene-butadiene copolymer, maleic acid copolymer, polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinyl acetate copolymer , polyurethane, polystyrene, polyvinylpyrrolidone, acrylic ester, acrylonitrile, methyl vinyl ether, and other water-based resins can be used alone or in combination of two or more.

The coating amount (dry weight) of the intermediate layer 5 is preferably 0.3 g/m ² to 10 g/m ² .

In this embodiment, the protective layer 6, which is the uppermost layer of the heat-sensitive recording material 1, does not contain elastic particles or the like, and reduces the wear of the thermal head and does not shorten its lifespan, which improves the suitability of the thermal head. In addition, in order to improve the sticking resistance, the structure is as follows. Sticking resistance refers to problems caused by the heat of the thermal head melting the top layer of the heat-sensitive recording material and sticking to the head, such as partial failure to print or distortion of the printed surface. It means that there is no.

The protective layer 6 of this embodiment has evaporation holes and cracks as recesses on its surface due to the evaporation of moisture, thereby creating a connection between the surface of the protective layer 6 and the thermal head. Reduces contact area.

In order to form recesses, particularly cracks, on the surface of the protective layer 6, a coating liquid containing hydrophobic resin particles is used as the coating liquid for forming the protective layer 6.

That is, the protective layer 6 uses an emulsion of hydrophobic resin particles as a binder, and in this embodiment, an emulsion in which hydrophobic acrylic resin particles are dispersed in water.

As described above, as the binder for the protective layer 6, an emulsion of hydrophobic resin particles is used, and no water-soluble polymer is used.

When a coating solution containing a water-soluble polymer is applied and dried, it is difficult to aggregate and forms a flexible coating film, so that cracks due to shrinkage do not occur.

On the other hand, when an emulsion of hydrophobic resin particles is applied and dried, the hydrophobic resin particles aggregate and shrink due to evaporation, causing cracks that become recesses on the surface of the protective layer 6. .

Since the cracks are formed by shrinkage due to aggregation of hydrophobic resin particles, they stop at the protective layer 6 and do not reach the intermediate layer 5.

Further, in this embodiment, in order to form evaporation holes that become recesses on the surface of the protective layer 6 due to evaporation of water, three layers, the heat-sensitive recording layer 4, the intermediate layer 5, and the protective layer 6, are formed as described above. Three layers are coated simultaneously using a curtain coater.

In the curtain coater, each coating liquid for forming the heat-sensitive recording layer 4, intermediate layer 5, and protective layer 6 is discharged from each slit and laminated. It is coated onto the undercoat layer 3 formed on the material 2 by allowing it to fall freely.

In the simultaneous coating of three layers using such a curtain coater, when the protective layer 6 dries, the hydrophobic resin particles begin to aggregate as described above and cracks are formed, water vapor escapes from the cracks, and a half-dry intermediate layer is formed. Layer 5 and thermosensitive recording layer 4 are dried and solidified. Most of the water vapor in the intermediate layer 5 and the heat-sensitive recording layer 4 is released from the cracks, but some of the water vapor is released by forming evaporation holes in the protective layer 6. Therefore, cracks and evaporation holes are formed near the protective layer 6.

In this embodiment, the evaporation holes formed in the protective layer 6 stop in the intermediate layer 5. Therefore, even if oil or the like adheres to the surface of the protective layer 6, which is the uppermost layer, it will not reach the heat-sensitive recording layer 4, and the heat-sensitive recording layer 4 will not be discolored.

The protective layer 6 contains additives such as a lubricant, a crosslinking agent, a dispersing agent, an antifoaming agent, and a waterproofing agent, as necessary.

Examples of fillers included in the protective layer 6 include aluminum hydroxide, aluminum oxide, aluminum silicate, heavy calcium carbonate, light calcium carbonate, titanium oxide, barium sulfate, silica gel, activated clay, talc, clay, and kaolinite. , diatomaceous earth, white carbon, magnesium carbonate, magnesium oxide, magnesium hydroxide, zinc oxide, polystyrene resin particles, urea-formalin resin particles, polyolefin resin particles, etc. may be used alone or in combination of two or more.

As an example of a coating liquid for forming the protective layer 6 of this embodiment, an emulsion in which a hydrophobic acrylic resin is dispersed in water, polyethylene wax as a lubricant, and calcium carbonate as a pigment are mixed in a ratio of 4:3:3. Thermal recording material 1 was manufactured using an aqueous dispersion suspension blended at a dry mass ratio of .

The coating amount (dry weight) of the protective layer 6 was 1 g/m ² .

FIG. 2 is an electron microscope (SEM) photograph of the surface of the protective layer 6 of the heat-sensitive recording material 1 manufactured as described above, and FIG. This is a microscopic (SEM) photograph.

As shown in FIG. 2, a large number of whitish streak-like cracks 10 and a small number of small evaporation holes 11 are formed on the surface of the protective layer 6.

Some of the cracks 10 are in the form of a single long line, but in most cases, a portion of the crack 10 is branched and extends in the form of a line.

The evaporation hole 11 is formed for moisture to evaporate during drying as described above, and is a depressed, approximately circular hole, as shown in FIG. 7, which will be described later.

In the comparative example shown in Figure 3, a water-soluble polymer was used as the binder instead of an emulsion in which a hydrophobic acrylic resin was dispersed in water, and each layer was formed sequentially instead of simultaneous multilayer formation using a curtain coater. It is something.

As shown in FIG. 3, the surface of the protective layer of the comparative example is a flat surface with no evaporation holes or cracks.

FIG. 4 is an enlarged electron microscope (SEM) photograph of the vicinity of the crack 10 at one location in FIG.

As shown in FIG. 4, the crack 10 has an open surface and extends inside the protective layer 6, that is, in the thickness direction of the protective layer 6.

FIG. 5 is an electron microscope (SEM) photograph in which a region other than the crack 10 in FIG. 4 is further enlarged.

As mentioned above, the protective layer 6 uses a binder containing hydrophobic resin particles, and as shown in FIG. It can be seen that they are arranged in such a way that the

According to this embodiment, as described above, the cracks 10 serving as recesses and the moisture evaporation holes 11 are formed on the surface of the protective layer 6, which is the uppermost layer of the heat-sensitive recording material 1. The surface becomes uneven. This reduces the contact area between the protective layer 6 and the thermal head, reduces wear on the thermal head, improves suitability for the thermal head, and improves sticking resistance.

Further, as in Patent Document 1, there is no need to mix elastic particles or the like into the constituent material of the protective layer 6, and the thickness of the protective layer 6 can be made thinner, for example, less than 1 μm, and in this embodiment, the thickness of the protective layer 6 can be reduced. The thickness can be approximately .8 μm. Thereby, the cost can be reduced and the distance from the surface of the protective layer 6 to the heat-sensitive recording layer 4 can be shortened, so that heat from the thermal head is efficiently conducted to the heat-sensitive recording layer 4.

Furthermore, since the cracks 10 on the surface of the protective layer 6 develop in the thickness direction inside the protective layer 6, the cracks 10 divide the protective layer 6 in a direction perpendicular to the thickness direction, that is, in the lateral direction. That will happen. Thereby, heat from the thermal head is suppressed from radiating in the lateral direction, and is efficiently conducted to the lower heat-sensitive recording layer 4 in the thickness direction.

In order to reduce the contact area between the protective layer 6 and the thermal head, it is preferable that the approximately circular moisture evaporation holes 11 have an average diameter of 2 μm or more.

The average diameter of the evaporation holes 11 is calculated by observing the surface of the protective layer 6 using an electron microscope (SEM) and measuring the diameter of the evaporation holes 11 per unit area, for example, 1 mm ² . Further, the number of evaporation holes 11 is preferably 30 or more, and more preferably 40 or more, per 1 mm ² of evaporation holes 11 having an average diameter of 5 μm or more.

In the heat-sensitive recording material 1 of this embodiment, by adjusting the composition of the protective layer 6, etc., the surface of the protective layer 6 can be formed with a large number of evaporation holes, as shown in the electron microscope (SEM) photograph of FIG. 11 and a small number of cracks 10, or, as shown in the electron microscopy (SEM) photograph of FIG. It is also possible to do this.

In the above embodiment, the three layers of the heat-sensitive recording layer 4, the intermediate layer 5, and the protective layer 6 are simultaneously coated in multiple layers using a curtain coater, but the method is not limited to simultaneous multi-layer coating. may be formed.

In the above embodiment, the undercoat layer 3 and the intermediate layer 5 are formed on the base material 2, but in another embodiment of the present invention, at least one of the undercoat layer 3 and the intermediate layer 5 is omitted. You may.

1 Heat-sensitive recording material 2 Base material 3 Undercoat layer 4 Heat-sensitive recording layer 5 Intermediate layer 6 Protective layer 10 Cracks (recesses)
11 Evaporation hole (recess)

Claims (6)

A heat-sensitive recording material in which at least a heat-sensitive recording layer and a protective layer serving as an uppermost layer are laminated on a base material,
A recess that does not reach the heat-sensitive recording layer is formed on the surface of the protective layer.
A heat-sensitive recording medium characterized by the following. A heat-sensitive recording material in which at least a heat-sensitive recording layer and a protective layer serving as an uppermost layer are laminated on a base material,
The protective layer is composed of hydrophobic resin particles.
characterized by
Heat sensitive recording material. the recess is at least one of a moisture evaporation hole and a crack;
The thermosensitive recording medium according to claim 1. The protective layer does not contain a water-soluble polymer.
The heat-sensitive recording material according to any one of claims 1 to 3. an intermediate layer is formed between the protective layer and the heat-sensitive recording layer;
The heat-sensitive recording material according to any one of claims 1 to 3. An undercoat layer containing hollow particles is formed between the base material and the heat-sensitive recording layer.
The heat-sensitive recording material according to any one of claims 1 to 3.

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