JPH0542763A - Thermal recording medium - Google Patents

Abstract

PURPOSE:To provide a thermal recording medium having excellent printability to aqueous ink without damaging necessary characteristics such as recording characteristics, storage stability or the like. CONSTITUTION:In a thermal recording medium formed by successively laminating a thermal recording layer, a protective layer and an ink absorbing layer to at least the single layer of a support, the ink absorbing layer is constituted of a resin component containing at least a polyvinyl pyrrolidone resin and the N-vinyl pyrrolidone monomer component of the polyvinyl pyrrolidone resin is within the range of 0.5-65% by wt. of all of the monomer components constituting the resin component. Since the thermal recording medium has acting effect excellent in the printability to aqueous ink, it can be adapted to a wide use especially suitable for ticket papers such as a ticket or a pass, a prepaid card or a POS label.

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 for 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 heat-sensitive recording method has less noise during recording, does not require development and fixing, is maintenance-free, has a relatively inexpensive and compact device, and provides coloration obtained. It is widely used as computer output, facsimile, recorder paper for calculators and various measuring machines, and ticket paper for vending machines because it has a very clear image.

As described above, the conventional thermal recording paper used for various purposes has not only recording characteristics,
Image storage stability such as chemical resistance and water resistance is required, and as disclosed in Japanese Patent Laid-Open No. 57-188392 and many others, a protective layer is provided on the heat-sensitive recording layer. ing. 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 is 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 sufficiently examined for their recording characteristics, chemical resistance, water resistance and the like as described above, they are not suitable for printing such as ink absorbability, drying property and fixing property for water-based ink. The 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 inks, and in addition, in order to improve blocking resistance under high humidity conditions, an emulsion-based resin is used. Water resistance is achieved by suppressing water absorption by using a water resistant agent. Further, it is expected that the amount of the pigment additive is increased to improve the absorbability of the water-based ink, but the transparency of the protective layer is lowered, and the problem of the sharpness of the image of the heat-sensitive recording layer is lowered. ..
As described above, in the conventional thermosensitive 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 excellent 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. The present invention provides a heat-sensitive recording medium having on its surface.

[0006]

The present invention is a thermosensitive recording medium comprising a support, on at least one side of which a thermosensitive recording layer, a protective layer and an ink absorbing layer are sequentially laminated, wherein the ink absorbing layer is at least polyvinyl. It is composed of a resin component containing a pyrrolidone-based resin, and the N-vinylpyrrolidone-based monomer component of the polyvinylpyrrolidone-based resin is in the range of 0.5 to 65% by weight based on all the monomer components constituting the resin component. The heat-sensitive recording medium is characterized in that

Examples of the polyvinylpyrrolidone-based resin used in the present invention include homopolymers and copolymers of N-vinylpyrrolidone-based monomers. The copolymerization form is
Random copolymerization, block copolymerization, graft copolymerization, etc. are not particularly limited. Here, the N-vinylpyrrolidone-based monomer means N-vinylpyrrolidone and a derivative thereof, and examples of the derivative include N-vinyl-3-methylpyrrolidone, N-vinyl-5-methylpyrrolidone, and N-vinylpyrrolidone. Examples thereof include those having a substituent on the pyrrolidone ring such as vinyl-3,3,5-trimethylpyrrolidone and N-vinyl-3-benzylpyrrolidone.

As the polyvinylpyrrolidone-based resin as described above, polyvinylpyrrolidone K-30, K-60, K-90 represented by the K value in the viscosity formula of Fiekencher, which is a homopolymer of N-vinylpyrrolidone. , K-12
0 or the like can be used. As the N-vinylpyrrolidone-based monomer copolymer, a copolymer with another copolymerizable vinyl-polymerizable monomer is used, and among them, the N-vinylpyrrolidone-based monomer and other basic nitrogen atom-containing vinyl are used. A copolymer with a polymerizable monomer is suitable.

The basic nitrogen atom-containing vinyl-polymerizable monomer copolymerized with the N-vinylpyrrolidone-based monomer includes N-vinylpiperidone, N-vinylcaprolactam, N-vinyloxazoline, N-vinyl-2-oxazolidone and N-. Nitrogen-containing heterocycle-containing monomers such as vinylimidazole and vinylpyridine, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth)
Examples thereof include (meth) acrylic monomers such as acrylate, acrylamide, N-alkylol acrylamide, and the like. Among these, dialkylaminoethyl (meth) acrylate is particularly preferable. In addition, the nitrogen portion of the dialkylaminoethyl (meth) acrylate is
It is likewise suitable even if a primary ammonium salt is formed.
Such a copolymer with a basic nitrogen atom-containing vinyl-polymerizable monomer can obtain good printability of an equivalent aqueous ink with a relatively small amount of N-vinylpyrrolidone-based monomer component that causes blocking. It has the effect of.

The copolymerizable component with the N-vinylpyrrolidone-based monomer in the present invention includes the following vinyl polymerizable monomers in addition to the basic nitrogen atom-containing vinyl monomer. For example, (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate,
Isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate,
t-butyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate, cyclohexyl ( (Meth) acrylate, tetrahydrofurfuryl (meth) acrylate, acrylonitrile, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, glycidyl (meth) acrylate, n-alkoxyalkyl (meth) acrylate, alkylcarbitol (Meth) acrylic monomers such as (meth) acrylate, alkyltriglycol (meth) acrylate, perfluoroalkyl (meth) acrylate, fumaric acid, maleic acid Unsaturated acids such as itaconic acid, ethylene, propylene, vinyl chloride, vinyl acetate,
Examples thereof include, but are not limited to, vinyl alcohol, styrene, vinyltoluene, divinylbenzene, vinyldene chloride, ethylene tetrafluoride, vinylidene fluoride and the like. ..

In the present invention, the polyvinylpyrrolidone-based resin as described above is contained in the ink absorbing layer in an amount of 0.5 to 0.5 out of all the monomer components constituting the resin component of the ink absorbing layer as the amount of the N-vinylpyrrolidone-based monomer component. 65% by weight,
It is necessary that the content is preferably 5 to 50%. Here, if the content is less than 0.5% by weight, good printability of the water-based ink cannot be obtained.
If it exceeds 5% by weight, the absorption of N-vinylpyrrolidone is so strong that blocking may occur under high humidity conditions, which is not preferable.

In the present invention, the ink absorbing layer contains the above-mentioned polyvinylpyrrolidone-based resin so that the N-vinylpyrrolidone-based monomer component has a specific amount as described above. If necessary, various water-soluble or water-dispersible polymers can be used. Examples of such a polymer include casein, gelatin, oxidized starch, 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-vinyl acetate copolymer, emulsions such as SBR and NBR, latex, and the like can be used alone or in an appropriate mixture.

In the ink absorbing layer, various pigments such as clay, talc, diatomaceous earth, alumina, and the like may be added, if necessary, in order to improve matching 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. are used, and a lubricity improver such as zinc stearate or calcium stearate or fluorine. Mold release agents such as resin and silicone grease, and glyoxal, chrome meiban,
Water resistant agents such as melamine resin, melamine formaldehyde resin, polyamide resin, and polyamide-epichlorohydrin resin can be used.

Next, the thermosensitive recording layer in the present invention will be described. The heat-sensitive recording layer contains, as main components, a colorless or light-colored leuco dye and a color developer that develops the color of the leuco dye. 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 are not particularly limited. Further, as the color developing agent that 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 copolymer and styrene-butadiene copolymer, but are not limited thereto.

Further, in order to improve the recording sensitivity, various heat-fusible substances can be added to the heat-sensitive recording layer, if necessary. Examples of these heat-fusible substances include organic compounds having an appropriate melting point, for example, higher fatty acid amides such as stearic acid amide, beeswax, animal waxes such as shellac wax, and 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.
Also, inorganic and organic pigments as fillers such as 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 kinds of surfactants, antifoaming agents, antioxidants, ultraviolet absorbers and the like can be added as necessary.

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 coating is a dispersion liquid pulverized by a disperser such as a media type wet disperser, and the particle size of a leuco dye, a 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, etc., unnecessary coloring due to penetration of plasticizers, oils, and various other chemicals into the thermosensitive recording layer, and decolorization of recorded images. A water-soluble or water-dispersible polymer compound that is a binder is used. In addition, in order to improve the water resistance as necessary, a water resistant agent such as glyoxal, chrome alum, melamine resin, melamine-formaldehyde resin, polyamide resin, polyamide-epichlorohydrin resin is added to the binder before use. 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 cloth, non-woven cloth, and composites thereof 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 prepared by dispersing or dissolving the materials for forming each of the above layers 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 thermal 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 also 2 to 10 g.
/ M ² is suitable, but more preferably 3 to 8
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.

Further, the heat-sensitive recording medium of the present invention is excellent in printing with an aqueous ink by providing a magnetic recording layer between the support and the heat-sensitive recording layer or on the surface of the support where the heat-sensitive recording layer is not provided. As a suitable heat-sensitive magnetic recording medium, it can be used in a wide range of applications as ticket papers such as train tickets, pass tickets, and parking tickets.

The magnetic recording layer is composed of, for example, γ-Fe ₂ O ₃ and Fe.
Magnetic materials such as ₃ O ₄ , Co-γ-Fe ₂ O ₃ , and BaO · 6Fe ₂ O ₃ are used as a binder resin, for example, polymer compounds such as polyester resins and polyurethane resins, and various additives and solvents. A coating material prepared by kneading and dispersing with the above may be applied on a support, dried, and set. As a 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. It is also possible to provide a magnetic recording layer having excellent wear resistance and heat resistance 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.

[0022]

EXAMPLES The present invention will be described in detail below with reference to examples. In addition, all the parts showing the composition represent parts by weight. Example 1 The following composition [A] was used to produce a coating material for a heat-sensitive recording layer.
A dispersion liquid including [B] and [C] was prepared. [A] Liquid 3-dibutylamino-7- (о-chloroanilino) fluoran 30 parts Methylcellulose aqueous solution (solid content concentration 5%) 50 parts Water 20 parts [B] Liquid 4,4′-thiobis (2-methylphenol) 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 using the above dispersion liquid, and a dry weight of 7 g / m ² was applied to 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 heat-sensitive recording layer so that the dry weight was 4 g / m ² . Polyvinyl alcohol aqueous solution (solid content concentration 10%) 100 parts [C] liquid 20 parts Zinc stearate aqueous dispersion (solid content concentration 10%) 5 parts

Further, a coating material for the ink absorbing layer having the following composition was prepared and coated on the above-mentioned protective layer so as to have a dry coating amount of 2 g / m ² , to prepare a thermosensitive recording medium of the present invention. Polyvinyl alcohol aqueous solution (solid content concentration 10%) 83 parts [C] liquid 20 parts Aqueous dispersion of zinc stearate (solid content concentration 10%) 5 parts Polyvinylpyrrolidone resin (monomer composition; N-vinyl pyrrolidone / dimethylaminoethyl) Copolymer composed of methacrylate = 98/2, trade name "Copolymer 845" manufactured by GA Chemicals Corp., solid content concentration 20%) 8.5 parts

Example 2 A thermosensitive recording medium of the present invention was prepared in 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%) 78 parts [C] liquid 20 parts Aqueous dispersion of zinc stearate (solid content concentration 10%) 5 parts Polyvinylpyrrolidone resin (monomer composition; N-vinyl pyrrolidone / dimethylaminoethyl) Copolymer composed of methacrylate = 98/2, trade name “Copolymer 845” manufactured by GA Chemicals Corp., solid content concentration 20%) 12 parts

Example 3 A thermosensitive recording medium of the present invention was prepared in the same manner as in Example 1 except that the coating composition for the ink absorbing layer having the following composition was used. Carboxyl-modified polyvinyl alcohol aqueous solution (solid content concentration 10%, trade name "Gohsenol T330" manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 80 parts [C] liquid 20 parts Water dispersion of zinc stearate (solid content concentration 10%) 5 parts Polyvinyl Pyrrolidone-based resin (monomer composition; copolymer consisting of N-vinylpyrrolidone / quaternary ammonium chloride dimethylaminoethylmethacrylate = 8/2, manufactured by GF Chemicals Corp., trade name “Gaff Cut 755” solids) 20% concentration) 10 parts

Example 4 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%) 65 parts [C] liquid 20 parts Aqueous dispersion of zinc stearate (solid content concentration 10%) 5 parts Polyvinylpyrrolidone resin (monomer composition; N-vinyl pyrrolidone / vinyl acetate = Copolymer consisting of 6/4, trade name "PVA / VA S630", solid content concentration 20%, manufactured by GA Chemicals Corp. 35 parts

Example 5 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. Carboxyl-modified polyvinyl alcohol aqueous solution (solid content concentration 10%, trade name "Gothenol T330" manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 75 parts [C] solution 20 parts Zinc stearate aqueous dispersion (solid content concentration 10%) 5 parts Polyvinyl Pyrrolidone-based resin (monomer composition; copolymer consisting of N-vinylpyrrolidone / styrene = 3/7, trade name "ANTARA 430", solid content concentration 40%, manufactured by GF Chemicals Corp.) 18 parts

Example 6 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%) 55 parts [C] liquid 20 parts Zinc stearate aqueous dispersion (solid content concentration 10%) 5 parts Polyvinylpyrrolidone K-120 aqueous solution (solid content concentration 10%) 45 parts Implementation Example 7 A thermosensitive recording medium of the present invention was produced 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%) 95 parts [C] liquid 20 parts Aqueous dispersion of zinc stearate (solid content concentration 10%) 5 parts Polyvinylpyrrolidone K-120 aqueous solution (solid content concentration 10%) 5.5 Department

Example 8 A thermosensitive recording medium of the present invention 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%) 95.5 parts [C] liquid 20 parts Water dispersion of zinc stearate (solid content concentration 10%) 5 parts Polyvinylpyrrolidone K-90 aqueous solution (solid content concentration 10%) 0 .5 parts Example 9 A thermal 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%) 35 parts [C] liquid 20 parts Zinc stearate aqueous dispersion (solid content concentration 10%) 5 parts Polyvinylpyrrolidone K-120 aqueous solution (solid content concentration 10%) 65 parts

Example 10 A high-quality paper of 137 g / m ² was used as a support, and a magnetic recording layer coating composition having the following composition was previously used on the surface opposite to the surface on which the heat-sensitive recording layer was provided. 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 11 A thermosensitive recording medium of the present invention having a magnetic recording layer was prepared in exactly the same manner as in Example 10 except that the same paint as in Example 3 was used as the paint for the ink absorbing layer.

Comparative Example 1 A thermal recording medium for comparison was prepared in the same manner as in Example 1 except that the ink absorbing layer was not provided. Comparative Example 2 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] liquid 20 parts Aqueous dispersion of zinc stearate (solid content concentration 10%) 5 parts Polyvinylpyrrolidone K-90 aqueous solution (solid content concentration 10%) 0.3 Department

Comparative Example 3 A thermal recording medium for comparison was prepared in the same manner as in Example 1 except that the coating composition for the ink absorbing layer used had the following composition. Carboxyl-modified polyvinyl alcohol aqueous solution (solid content concentration 10%, Goseinol T330 manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 30 parts [C] liquid 20 parts Water dispersion of zinc stearate (solid content concentration 10%) 5 parts Polyvinylpyrrolidone K-90 Aqueous solution (concentration of solid content: 10%) 70 parts Comparative Example 4 A thermal recording medium for comparison 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. Polyvinylpyrrolidone K-90 aqueous solution (solid content concentration 10%) 30 parts [C] liquid 20 parts Zinc stearate aqueous dispersion (solid content concentration 10%) 5 parts

The content of the N-vinylpyrrolidone-based monomer component in the ink absorbing layers of the thermal recording media obtained in Examples 1 to 11 and Comparative Examples 1 to 4 is as shown in Table 1. Table 1 shows the results of evaluation of each item of these thermal recording media by the following methods. <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 a 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. ◎: prints that are hardly printed due to friction, ○: prints are slightly printed but there is no problem in practical use, ○: prints are fairly marked, △: prints are almost unusable And

<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 was conducted. A sample with little blocking and no problem in practical use was evaluated as ◯, a sample with some blocking was evaluated as Δ, and a sample that completely blocked and could not be used practically was evaluated as 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 10 and 11 were further applied to a vending machine for cash vouchers 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 mounting.

[0037]

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, it can be widely used as a thermosensitive magnetic recording medium having excellent printability for water-based ink, for example, ticket papers, pass tickets, parking tickets and the like. Can be used for.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryo Kaburagi, 3-1, Somune-cho, Shizuoka-shi, Shizuoka Prefecture

Claims (4)

[Claims] 1. A heat-sensitive recording medium comprising a support, on at least one side of which a heat-sensitive recording layer, a protective layer, and an ink-absorbing layer are sequentially laminated, the ink-absorbing layer containing at least a polyvinylpyrrolidone-based resin. Consists of
A heat-sensitive recording medium, wherein the N-vinylpyrrolidone-based monomer component of the polyvinylpyrrolidone-based resin is in the range of 0.5 to 65% by weight based on all the monomer components constituting the resin component. 2. The heat-sensitive recording medium according to claim 1, wherein the polyvinylpyrrolidone resin is a copolymer comprising at least an N-vinylpyrrolidone monomer and a basic nitrogen atom-containing vinyl polymerizable monomer. 3. The vinyl polymerizable monomer containing a basic nitrogen atom is a quaternary ammonium salt of dialkylaminoethyl (meth) acrylate and / or dialkylaminoethyl (meth) acrylate. Thermal recording medium. 4. 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. ..