JPH06210950A - Thermal recording medium - Google Patents

Abstract

PURPOSE:To obtain a thermal recording medium good in ink absorbability, drying properties and fixing properties by successively laminating a thermal recording layer, a protective layer and a specific mica-containing ink absorbing layer on a support. CONSTITUTION:A colorless or light-colored leuco dye and a developer such as alpha-naphthol are mixed to be compounded with an aqueous soln. of polyvinyl alcohol under stirring to prepare a coating solution for a thermal recording layer. An aqueous soln. of a binder such as polyvinyl alcohol is used as a coating soln. for a protective layer. Further, one or more kind of micas represented by formula I (wherein m is a number of 1/3-1 and n is a number of 2-8/3) and a polymeric binder such as an acrylic resin or polyvinyl alcohol are mixed in a dispersing medium under stirring to prepare a coating soln. for a protective layer. These coating solns. are successively applied to a support such as paper and dried to obtain a thermal recording medium wherein the thermal recording layer, the protective layer and the ink absorbing layer are successively laminated on the support.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording medium having excellent printability on a water-based ink on its surface, and in particular, ticket papers such as tickets and pass tickets, cards such as prepaid cards, and POS (Point of Point). Sales) The present invention relates to a thermal recording medium that can be applied to labels such as labels.

[0002]

2. Description of the Related Art In general, a heat-sensitive recording medium having a heat-sensitive recording layer mainly composed of a colorless or light-colored leuco dye and a developer which reacts with the leuco dye to develop a color is disclosed in JP-B-45-45.
Published in No. 14035, etc., it has been widely put into practical use. To perform recording on this heat-sensitive recording medium, a thermal printer or the like having a built-in thermal head is used. Compared to other conventional recording methods, such a thermal recording method has less noise during recording, does not require development and fixing, is maintenance-free, is relatively inexpensive and compact in equipment, and produces colors It is widely used as computer output, facsimile, recorder paper for calculators and various measuring machines, and ticket paper for automatic ticket vending machines because it has a very clear image.

As described above, conventional thermal recording media used for various purposes are required to have not only recording characteristics but also image storage stability such as chemical resistance and water resistance. As proposed in Japanese Patent Laid-Open No. 188392 and others, it has a structure in which a protective layer is provided on the heat-sensitive recording layer. The composition of such a protective layer is generally a water-soluble or water-dispersible polymer compound to which various additives such as pigments are added. In recent years, there has been a strong demand for printing with a water-based ink on the surface of the protective layer in the field of labels such as POS labels and ticket paper such as tickets, and in particular, in tickets, stamps using water-based ink are used instead of conventional scissors. The ticket inspection method is adopted.

However, although the conventional thermosensitive recording media have been fully examined for their recording characteristics, chemical resistance, water resistance and the like as described above, they are not suitable for printing such as ink absorption, drying and fixing properties for water-based ink. Printability was poor as little consideration was given. That is, a water-soluble resin such as polyvinyl alcohol that has been conventionally used as a protective layer does not provide sufficient printability for water-based ink, and in addition, in order to improve blocking resistance under high humidity conditions, an emulsion-based resin is used. Since water absorption is suppressed by using a water-repellent agent and a water-proofing agent, it has an adverse effect on printability with respect to water-based inks, which has an adverse effect. Moreover, although the absorptivity of the water-based ink can be improved by increasing the addition amount of the pigment, the problem that the transparency of the protective layer is lowered and the sharpness of the image of the thermosensitive recording layer is lowered occurs. Will end up. As described above, in the conventional thermal recording medium, the printability of the water-based ink cannot be satisfied, and a heat-sensitive recording medium having good printability and image storability as well as printability of the water-based ink is desired. It is the current situation.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has excellent printability for water-based ink without impairing the recording characteristics, storage stability and the like required for a thermal recording medium. That is, the present invention provides a heat-sensitive recording medium having ink absorbing properties, drying properties and fixing properties on its surface.

[0006]

The present invention is a thermal recording medium comprising a support, on at least one side of which a thermal recording layer, a protective layer and an ink absorbing layer are laminated in this order. A heat-sensitive recording medium containing at least one mica selected from the compounds represented by formula (1). (Na, Li) _m Mg _n Li _6-2n-m Si ₄ O ₁₀ (F, OH) ₂ (1) [wherein m is a number in the range of 1/3 to 1 and n is 2 to 8/3] Represents]

Examples of the mica represented by the general formula (1) used in the ink absorbing layer in the present invention include the following compounds. NaMg ₂ LiSi ₄ O ₁₀ F ₂ NaMg ₂ LiSi ₄ O ₁₀ (OH) ₂ NaMg _2.5 Si ₄ O ₁₀ F ₂ NaMg _2.5 Si ₄ O ₁₀ (OH) ₂ Na _2/3 Mg _7/3 Li _2/3 Si ₄ O ₁₀ F ₂ (vermiculite) Na _2/3 Mg _7/3 Li _2/3 Si ₄ O ₁₀ (OH) ₂ (vermiculite) Na _1/3 Mg _8/3 Li _1/3 Si ₄ O ₁₀ F ₂ (montmorillonite) ) Na _1/3 Mg _8/3 Li _1/3 Si ₄ O ₁₀ (OH) ₂ (montmorillonite) LiMg ₂ LiSi ₄ O ₁₀ F ₂ LiMg ₂ LiSi ₄ O ₁₀ (OH) ₂ Li _2/3 Mg _7/3 Li _2/3 Si ₄ O ₁₀ F ₂ Li _2/3 Mg _7/3 Li _2/3 Si ₄ O ₁₀ (OH) ₂ Li _1/3 Mg _8/3 Li _1/3 Si ₄ O ₁₀ F ₂ Li _{1 / 3} Mg _8/3 Li _1/3 Si ₄ O ₁₀ (OH) ₂

Generally, naturally occurring mica is (K) _m Mg _n Li _6-2n-m Si ₄ O ₁₀ (OH) ₂ [wherein m and n have the same meanings as in formula (1)] And has no swelling property. The specific mica represented by the general formula (1) used in the present invention has a structure in which potassium ion of naturally occurring mica is replaced with sodium ion or lithium ion, and has a swelling property in water. In the present invention, the term mica is used to include vermiculite and montmorillonite. The mica used in the present invention is, for example, “M
E-100 "(made by Corp Chemical)," Smectite SWF "(made by Corp Chemical)," Smectite SW "
It is marketed under the trade name of N "(made by Corp Chemical),
"ME-100" _{is, NaMg 2 LiSi 4 O 10 F} 2,
"Smectite SWF" is Na _1/3 Mg _8/3 Li _1/3 Si ₄
O ₁₀ F ₂ , "Smectite SWN" is Na _1/3 Mg _8/3 L
It has a composition of i _1/3 Si ₄ O ₁₀ (OH) ₂ .

The ink absorbing layer in the present invention comprises at least the mica represented by the above general formula (1) and a polymer binder. As the polymer binder, various water-soluble, water-dispersible, hydrophobic polymer compounds are used,
For example, acrylic resin, polyester resin, polyurethane resin, styrene-butadiene copolymer resin, acrylonitrile-butadiene copolymer resin, polyvinyl alcohol resin, water-soluble polyvinyl acetal resin, polyvinyl butyral resin, other vinyl resin, amide Examples of the resin include resin, oxidized starch, casein, polyethylene oxide, polyvinylpyrrolidone, silicone resin, cellulose resin, rosin-modified maleic acid resin, rosin-modified phenol resin, alkyd resin and coumarone-indene resin. These resins may be used alone or as a mixture. Particularly preferable polymer binders include polyvinyl alcohol resins, water-soluble polyvinyl acetal resins, polyvinyl pyrrolidone, and the like, from the viewpoint of blendability with mica, printability with aqueous ink, and the like.

In the ink absorbing layer, various pigments such as clay, talc, diatomaceous earth, alumina, and the like may be added as necessary to improve the matching property with the thermal head.
Calcium carbonate, calcium sulfate, zeolite, cellulose fine powder, polyethylene fine powder, silicone resin fine powder, phenol resin fine powder, benzoguanamine resin fine powder, etc. can be used, and a lubricity improver such as zinc stearate or calcium stearate or a fluororesin. Further, a release agent such as silicone grease and a waterproofing agent such as glyoxal, chrome alum, melamine resin, melamine formaldehyde resin, polyamide resin and polyamide-epichlorohydrin resin can be used.

In the ink absorbing layer having the composition as described above, the mixing ratio of mica is 5 to 80 in the total solid content in the layer.
It is preferably in the range of 40% by weight, particularly 40 to 60% by weight. If the proportion of the swelling mica is less than 5% by weight, sufficient printability for water-based ink cannot be obtained, and if it is added in excess of 80% by weight, the effect corresponding to the addition amount cannot be obtained. However, the physical strength of the ink absorbing layer may be weakened, and the ink absorbing layer may peel off.

Next, the thermosensitive recording layer in the present invention will be described. The heat-sensitive recording layer contains a colorless or light-colored leuco dye and a color developer that develops the color of the leuco dye as main components. Typical leuco dyes used include crystal violet lactone, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-cyclohexylamino-6-chlorofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3-cyclohexylmethylamino-6- Methyl-7-anilinofluorane, 3-ethylisoamylamino-6-methyl-7
-Anilinofluorane, 3-diethylamino-7- (о
-Chloroanilino) fluorane, 3-dibutylamino-
7- (o-chloroanilino) fluorane and the like, but not limited thereto. Further, as the color developer which reacts with the leuco dye to develop color, α-naphthol, β
-Naphthol, 4-t-butylphenol, 4-t-octylphenol, 4-phenylphenol, 2,2-
Bis (p-hydroxyphenyl) propane, 2,2-bis (p-hydroxyphenyl) butane, 4,4′-cyclohexylidene diphenol, 2,2-bis (2,5-)
Dibromo-4-hydroxyphenyl) propane, 4,
4'-isopropylidene bis (2-t-butylphenol), 2,2'-methylenebis (4-chlorophenol), 4,4'-thiodiphenol, 4,4'-sulfonyldiphenol, benzoic acid, salicylic acid, There are derivatives such as gallic acid, but not limited to these.

As the binder used in the heat-sensitive recording layer, various water-soluble or water-dispersible polymer compounds are used, such as polyvinyl alcohol, casein, oxidized starch, gelatin, isobutylene-maleic anhydride resin,
Diisobutylene-maleic anhydride resin, styrene-maleic anhydride resin, carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, polyvinyl acetate, poly (meth) acrylic acid ester, vinyl chloride-
Examples thereof include vinyl acetate copolymers and styrene-butadiene copolymers, but are not limited thereto.

Further, in order to improve the recording sensitivity, various heat fusible substances can be added to the thermosensitive recording layer, if necessary. Examples of these heat-fusible substances include organic compounds having a suitable melting point, for example, higher fatty acid amides such as stearic acid amide, animal waxes such as beeswax and shellac wax, vegetable waxes such as carnauba wax, Mineral wax such as montan wax, paraffin wax, microcrystalline wax, higher fatty acid, ester of higher fatty acid, aromatic carboxylic acid ester such as dimethyl terephthalate and diphenyl phthalate, alkylnaphthalene derivative, alkyldiphenyl derivative, alkylterphenyl derivative, etc. Is used.
Furthermore, in the heat-sensitive recording layer, inorganic and organic pigments as a filler, for example, clay, talc, diatomaceous earth, alumina, calcium carbonate, calcium sulfate, zeolite, cellulose fine powder, polyethylene fine powder, silicone resin fine powder. , Phenol resin fine powder, benzoguanamine resin fine powder and the like can be added to improve the sharpness of the color image. In addition, various surfactants, antifoaming agents, antioxidants, and ultraviolet absorbers can be added as required.

The heat-sensitive recording layer in the present invention has the composition as described above, and a coating comprising a leuco dye, a developer and a binder, and other compounds added as necessary is provided on a support. Although it is provided by coating and drying, such a paint is a dispersion liquid pulverized by a disperser such as a media type wet disperser, and the particle size of the leuco dye, the color developer or the like to be dispersed. Is 5 μm or less, particularly preferably 3
It is desirable that the thickness be less than or equal to μm in terms of recording characteristics.

Further, the protective layer in the present invention is
It is provided in order to prevent pressure coloring caused by scratching, unnecessary coloring due to penetration of plasticizers, oils, and other chemicals into the thermosensitive recording layer, and decolorization of recorded images. A water-soluble or water-dispersible polymer compound which is a binder is used. In addition, in order to improve the water resistance as necessary, a water-proofing agent such as glyoxal, chrome alum, melamine resin, melamine-formaldehyde resin, polyamide resin, polyamide-epichlorohydrin resin is added to the binder and used. be able to.

The support used in the heat-sensitive recording medium of the present invention includes paper, thermoplastic resin sheet, metal foil, metal plate,
Metal deposition sheet, metal fiber sheet, ceramic sheet,
Woven fabrics, non-woven fabrics, and composites of these are not particularly limited. In the present invention, in order to form a heat-sensitive recording layer, a protective layer and an ink absorbing layer on the support, a coating solution in which the materials for forming each of the above layers are dispersed or dissolved is subjected to a roll coating method and a blade coating method. , Spray coating, air knife coating, rod bar coating and the like. The preferable coating amount of the heat-sensitive recording layer and the protective layer is
² to 10 g / m ² in the thermal recording layer, more preferably 5
~ 8 g / m ² . Similarly, the protective layer is 2 to 10 g.
/ M ² is suitable, but more preferably 3 to 8
It is g / m ² . The preferable coating amount of the ink absorbing layer is 1 to
10 g / m ^2, particularly preferably from 2 to 4 g / m ^2.

The thermal recording medium of the present invention may further comprise an under layer between the support and the thermal recording layer to enhance the smoothness of the surface of the support and improve the sharpness of image quality. You can Further, by providing a back layer on the surface of the support opposite to the surface on which the thermosensitive recording layer is provided, it is possible to prevent the penetration of various chemicals from the back surface of the thermosensitive recording medium and eliminate the need for the thermosensitive recording layer. It is possible to prevent coloring and erasing of recorded images. The under layer and the back layer are formed by mainly using various water-soluble or water-dispersible polymer compounds that are binders used in the thermosensitive recording layer, and by adding pigments and various additives as necessary. can do. The coating amount of both the under layer and the back layer is 0.5 to 10 g / m ²
A degree is preferable. It is also possible to further improve the surface smoothness by applying a calendar treatment after coating the under layer.

Further, in the heat-sensitive recording medium of the present invention, by providing the magnetic recording layer between the support and the heat-sensitive recording layer or on the surface of the support on which the heat-sensitive recording layer is not provided, excellent printing with water-based ink is possible. The heat-sensitive magnetic recording medium having suitability can be used in a wide range of applications as ticket papers such as boarding tickets, pass tickets, and parking tickets. The magnetic recording layer is formed of, for example, γ-Fe ₂ O ₃ , Fe ₃ O ₄ , Co-γ-F.
Preparation of magnetic materials such as e ₂ O ₃ and BaO.6Fe ₂ O ₃ by kneading / dispersing a suitable binder resin, for example, a polymer compound such as polyester resin or polyurethane resin, various additives, solvents, etc. The coating composition may be applied on a support, dried, and set. As the method at this time, various coating methods can be applied as in the case of providing the heat-sensitive recording layer, the protective layer, and the ink absorbing layer. Further, a magnetic recording layer having excellent abrasion resistance and heat resistance can be provided by using an ultraviolet curable binder or an electron beam curable binder. When the heat-sensitive recording layer is provided on the magnetic recording layer, it is preferable to provide a hiding layer for hiding the coloring of the magnetic recording layer between the magnetic recording layer and the heat-sensitive recording layer.

[0020]

EXAMPLES The present invention will be described in detail below with reference to examples. In addition, all the numbers showing the composition represent parts by weight. Example 1 In order to produce a coating material for a heat-sensitive recording layer, the following composition [A] was used.
A dispersion liquid including [B] and [C] was prepared. [A] liquid-3-dibutylamino-6-methyl-7-anilinofluorane 30 parts-Methylcellulose aqueous solution (solid content concentration 5%) 50 parts-Water 20 parts [B] liquid-4-isopropoxy-4 ' -Hydroxydiphenyl sulfone 30 parts-Polyvinyl alcohol aqueous solution (solid content concentration 5%) 50 parts-Water 20 parts [C] liquid-Kaolin 40 parts-Polyvinyl alcohol aqueous solution (solid content concentration 5%) 40 parts-Water 20 parts

[A] to [C] obtained as described above
A coating material for the heat-sensitive recording layer having the following composition was prepared by using the dispersion liquid of No. 1, and a dry weight of 7 g / m ^{2 was applied to} a wood free paper having a basis weight of 60 g / m ^2.
And a thermal recording layer was provided. -[A] liquid 30 parts- [B] liquid 90 parts- [C] liquid 100 parts-Polyvinyl alcohol aqueous solution (solid content concentration 10%) 150 parts Next, a coating material having the following composition was prepared as a protective layer,
It was coated on the thermosensitive recording layer so that the dry coating amount was 4 g / m ² .・ Polyvinyl alcohol aqueous solution (solid content concentration 10%) 100 parts ・ [C] liquid 20 parts ・ Aqueous dispersion of zinc stearate (solid content concentration 10%) 5 parts Furthermore, a coating material for ink absorbing layer having the following composition is prepared. Then
The thermal recording medium of the present invention was produced by coating the above protective layer so that the dry coating amount was 2 g / m ² . -Polyvinyl alcohol aqueous solution (solid content concentration 10%) 100 parts-Swellable mica water dispersion liquid (trade name "ME-100", manufactured by Corp Chemical Co., solid content concentration 5%) 380 parts- [C] solution 10 parts- Aqueous dispersion of zinc stearate (solid content 10%) 5 parts

Example 2 A thermosensitive recording medium of the present invention was produced in exactly the same manner as in Example 1 except that the coating composition for the ink absorbing layer used had the following composition. -Polyvinyl alcohol aqueous solution (solid content concentration 10%) 100 parts-Swellable mica water dispersion liquid (trade name "ME-100") 190 parts- [C] liquid 10 parts-Zinc stearate water dispersion liquid (solid content concentration) 10%) 5 parts Example 3 A thermosensitive recording medium of the present invention was prepared in exactly the same manner as in Example 1 except that the following composition was used as the coating material for the ink absorbing layer. -Polyvinyl alcohol aqueous solution (solid content concentration 10%) 90 parts-Polyvinylpyrrolidone aqueous solution (solid content concentration 10%) 10 parts-Swellable mica water dispersion (trade name "ME-100") 75 parts- [C] liquid 10 Parts-Aqueous dispersion of zinc stearate (solid content concentration 10%) 5 parts Example 4 Smectite aqueous dispersion as a swelling mica in the ink absorbing layer coating (trade name "SWN", manufactured by Corp Chemical Co., solid content concentration) A thermal recording medium of the present invention was prepared in exactly the same manner as in Example 1 except that 5%) was used. Example 5 A smectite aqueous dispersion (trade name "SWN") was used as the swellable mica in the coating material for the ink absorbing layer, except that
A thermal recording medium of the present invention was produced in exactly the same manner as in Example 2. Example 6 This example was carried out in the same manner as in Example 3 except that a smectite aqueous dispersion (trade name “SWF”, manufactured by Cope Chemical Co., solid content concentration 5%) was used as the swelling mica in the coating material for the ink absorbing layer. A thermal recording medium of the invention was produced.

Example 7 Using 137 g / m ² of high-quality paper as a support, a magnetic recording layer coating material having the following composition was previously used on the surface opposite to the surface on which the heat-sensitive recording layer was provided, and a magnetic recording medium having a thickness of 13 μm was used. A thermosensitive recording medium of the present invention having a magnetic recording layer was produced in exactly the same manner as in Example 1 except that the recording layer was provided.・ Barium ferrite (coercive force 3000 oersted, average particle size 0.6 μm) 100 parts ・ Polyester resin (Byron 200, manufactured by Toyobo Co., Ltd.) 40 parts ・ Carbon black (Mitsubishi Carbon # 40, manufactured by Mitsubishi Kasei) 5 parts ・Lecithin 2 parts-Methyl ethyl ketone 150 parts-Toluene 180 parts

Example 8 A thermosensitive recording medium of the present invention having a magnetic recording layer was prepared in exactly the same manner as in Example 7 except that the same coating material as in Example 3 was used as the coating material for the ink absorbing layer. Example 9 A thermosensitive recording medium of the present invention having a magnetic recording layer was produced in exactly the same manner as in Example 7, except that the same coating material as in Example 4 was used as the coating material for the ink absorbing layer. Example 10 A thermosensitive recording medium of the present invention having a magnetic recording layer was produced in exactly the same manner as in Example 7 except that the same coating material as in Example 6 was used as the ink absorbing layer coating material.

Comparative Example 1 A thermal recording medium for comparison was prepared in exactly the same manner as in Example 1 except that the coating composition for the ink absorbing layer used had the following composition. -Polyvinyl alcohol aqueous solution (solid content concentration 10%) 100 parts- [C] solution 20 parts-Aqueous dispersion of zinc stearate (solid content concentration 10%) 5 parts Comparative Example 2 As a coating material for an ink absorbing layer, the following composition was used. A thermal recording medium for comparison was prepared in exactly the same manner as in Example 1 except that the one used was used. -Polyvinylpyrrolidone K-90 aqueous solution (solid content concentration 10%) 100 parts- [C] solution 20 parts-Zinc stearate aqueous dispersion (solid content concentration 10%) 5 parts

Comparative Example 3 A thermal recording medium for comparison was prepared in exactly the same manner as in Example 1 except that the coating composition for the ink absorbing layer used had the following composition. -Polyvinyl alcohol aqueous solution (solid content concentration 10%) 100 parts-Silica mica (trade name "Microclean", manufactured by Dowa Mining Co., Ltd.) 20 parts- [C] liquid 10 parts-Aqueous dispersion of zinc stearate (solid content concentration) 10%) 5 parts Comparative Example 4 A thermal recording medium for comparison was prepared in the same manner as in Example 1 except that the following composition was used as the coating material for the ink absorbing layer. -Polyvinyl alcohol aqueous solution (solid content 10%) 100 parts-Calcium carbonate 20 parts- [C] solution 10 parts-Zinc stearate aqueous dispersion (solid content 10%) 5 parts

The thermal recording media obtained in Examples 1 to 10 and Comparative Examples 1 to 4 were evaluated for each item by the following methods, and the results are shown in Table 1. <Recording characteristics> Applied power 0.5 W / dot, pulse width 1.0 msec with a thermal printer manufactured by Matsushita Electronic Components Co., Ltd.
Recorded with, and the density of the black solid part is Macbeth reflection densitometer RD-
The recording density was evaluated by measuring at 914. <Printability> Using a stamp with water-based ink,
Five seconds after stamp printing on the protective layer, the printed part was rubbed with a fingertip to evaluate the drying property and the fixing property. When the print was hardly printed due to friction, the mark was ○, when the print was marked, the mark was Δ, and when the print was hardly printed and could not be put to practical use, the mark was marked.

<Blocking resistance> Under the environment of 30 ° C. and 80% RH, 20 thermal recording media are stacked and a load of 60 is applied.
After standing for 24 hours under the condition of kg / m ² , a blocking test of the coated surface was conducted. When there was almost no blocking and there was no problem in practical use, it was marked with ◯, and when blocking occurred, it was marked with x.

[Table 1]

As is clear from Table 1, the thermosensitive recording medium of the present invention is an excellent thermosensitive recording medium having good printability for water-based ink without deteriorating the characteristics such as recording characteristics and blocking property. It was confirmed that there is. Also,
The thermosensitive magnetic recording media obtained in Examples 7 to 10 were applied to a vending machine for cash vouchers further having a thermosensitive recording mechanism, and predetermined magnetic information was written, read, and the balance display amount was applied to the thermosensitive recording surface. It was confirmed that there was no problem in practical use.

[0031]

The heat-sensitive recording medium of the present invention has an excellent effect that it has good printability for water-based ink without deteriorating necessary characteristics such as recording characteristics, chemical resistance, water resistance and blocking resistance. It is a thing. Further, by providing a magnetic recording layer on the thermosensitive recording medium of the present invention, as a thermosensitive magnetic recording medium having excellent printability for water-based ink, for example, a wide range of applications such as ticket, pass ticket, parking ticket, etc. Can be used for.

Claims (2)

[Claims] 1. A thermal recording medium comprising a support, on at least one side of which a thermal recording layer, a protective layer and an ink absorbing layer are sequentially laminated, wherein the ink absorbing layer is a compound represented by the following general formula (1). A thermal recording medium containing at least one mica selected from the group consisting of: (Na, Li) _m Mg _n Li _6-2n-m Si ₄ O ₁₀ (F, OH) ₂ (1) [wherein m is a number in the range of 1/3 to 1 and n is 2 to 8/3] Represents] 2. The heat-sensitive recording medium according to claim 1, wherein a magnetic recording layer is provided between the support and the heat-sensitive recording layer or on the surface of the support on which the heat-sensitive recording layer is not provided. .