JP2020152022A - Heat-sensitive recording medium, and manufacturing method of heat-sensitive recording medium - Google Patents

Abstract

To provide a heat-sensitive recording medium having sufficient adhesiveness even to a surface coated with dimethyl silicone, and excellent in illegal replacement prevention.SOLUTION: A heat-sensitive recording medium has at least an adhesive layer, a support medium and a thermo-sensitive recording layer. When trying peeling-off after allowing adhesion onto a plane having a surface comprising dimethyl silicone, the heat-sensitive recording medium is torn off.SELECTED DRAWING: Figure 1

Description

The present invention relates to a heat-sensitive recording medium and a method for manufacturing the heat-sensitive recording medium.

Thermal recording media include, for example, POS fields such as fresh foods, lunch boxes, and prepared foods, copying fields such as books and documents; communication fields such as facsimiles, ticketing fields such as ticket vending machines, receipts, and receipts, and baggage in the aircraft industry. It is widely used in various fields such as tags for use.

In particular, in the retail industry such as supermarkets and department stores, thermal labels displaying product names, prices, and barcodes are affixed to products. Retailers often cut prices to prevent unsold items, such as before closing. At that time, a label (markdown label) on which the price after price reduction and the barcode are printed on the existing label is attached to the target product for the price reduction. As such a markdown label, for example, a strong adhesive is used and the label is perforated in order to prevent unauthorized replacement of the markdown label attached to one product to another product. Has been proposed (see, for example, Patent Document 1).
On the other hand, by applying a release layer to the surface, the use of linerless labels that can be used in roll form without release paper is expanded, and such linerless labels have been proposed (see, for example, Patent Document 2). ).

An object of the present invention is to provide a heat-sensitive recording medium which has sufficient adhesiveness to a surface coated with dimethyl silicone and has excellent anti-tampering property.

The heat-sensitive recording medium of the present invention as a means for solving the above-mentioned problems is a heat-sensitive recording medium having at least an adhesive layer, a support, and a heat-sensitive recording layer, and is peeled off after the surface is adhered to a flat surface made of dimethyl silicone. If you try, it will tear.

According to the present invention, it is possible to provide a heat-sensitive recording medium which has sufficient adhesiveness to a surface coated with dimethyl silicone and is excellent in preventing unauthorized replacement.

FIG. 1 is a schematic view showing an example of the heat-sensitive recording medium of the present invention. FIG. 2 is a schematic view showing another example of the heat-sensitive recording medium of the present invention. FIG. 3 is a schematic view showing another example of the heat-sensitive recording medium of the present invention.

(Thermal recording medium)
The heat-sensitive recording medium of the present invention is a heat-sensitive recording medium having at least an adhesive layer, a support, and a heat-sensitive recording layer, and has an adhesive layer that is torn when the surface is adhered to a flat surface made of dimethyl silicone and then peeled off. Further, if necessary, it has a heat insulating layer, a protective layer, and other layers.

The present inventors have studied a heat-sensitive recording medium that has sufficient adhesiveness to a surface coated with dimethyl silicone and is excellent in preventing unauthorized replacement, and obtained the following findings.
In the case of a conventional heat-sensitive recording medium used as a price reduction label (markdown label) used when reducing the price of a product, it is necessary to attach the price reduction label on the label already attached to the product. However, for labels already attached to products, linerless labels in which a release layer mainly made of dimethyl silicone is formed on the label surface are often used, and are used for conventional markdown labels. The acrylic pressure-sensitive adhesive has a problem that the adhesiveness to the peeling layer is low, the price reduction label is easily peeled off without breaking, and the prevention of unauthorized replacement is low.

Therefore, the present inventors have a characteristic that the heat-sensitive recording medium is torn when the surface is adhered to a flat surface made of dimethyl silicone and then peeled off, so that the label is compared with a mark-down label having a conventional acrylic adhesive. As a result, it has sufficient adhesiveness to the surface coated with dimethyl silicone as a release layer, and even when it is peeled off after being stretched on such a surface, it is peeled off with breakage, so that it is excellent in preventing unauthorized replacement. We have found that it can be used as a heat-sensitive recording medium.

The flat surface made of dimethyl silicone is a surface made of dimethyl silicone.
Examples of the molecular weight of the dimethyl silicone include 390.
The "flat surface" means that the surface roughness (Ra) measured by a surface roughness meter (manufactured by Mitutoyo Co., Ltd.) satisfies 0.2 or more and 1.0 or less.
The "plane" does not have to be perfectly flat and may have waviness.
The "adhesion" refers to a state in which the surface is adhered to the flat surface made of dimethyl silicone when a pressure of 2 kgf is applied to the entire surface once with a roller (manufactured by Tester Sangyo Co., Ltd.). Means.
"Trying to peel off" means holding one end of the thermal recording material, folding it back in the 10 ° to 180 ° direction, and slowly pulling it.
By "torn" is meant a state in which at least one of the coating layer and the base material in the thermal recording medium, or between layers, is broken and cannot be restored to its original state.
Specific examples of the flat surface whose surface is made of dimethyl silicone include a peeling layer of a linerless label.

<Adhesive layer>
The adhesive layer is a layer made of an adhesive, and the value obtained by multiplying the adhesive strength (mN / 25 mm) of the heat-sensitive recording medium measured by adhering to a flat surface made of dimethyl silicone by 3 is the value of the heat-sensitive recording medium. It is larger than the paper strength (mN / 25 mm) and has other components as needed.

The adhesive strength means the adhesive strength measured by the method shown below.

-Measurement method of adhesive strength-
Used for thermal recording medium (thermal label) 25 μm synthetic paper coated with almost the same amount of adhesive was cut out to a width of 25 mm and a length of 70 mm, and 25 mm from one end was pasted on an aluminum substrate. A 2 kg crimping roller was reciprocated once on a flat surface made of silicone to bring it into close contact, and allowed to stand at a temperature of 23 ° C. and a relative humidity of 50% for 24 hours. One end (one side) of the short axis of the heat-sensitive recording medium is folded back in the 180 ° direction, the other end (the other side) facing the heat-sensitive recording medium is fixed to the force gauge, and 180 at a speed of 300 ± 30 mm / min with respect to the substrate. The weight when it was pulled in the ° direction and peeled off was measured. This was used as a reference value for the adhesive strength between the thermal recording medium and the synthetic paper.

As the adhesive strength, for example, the adhesive strength measured by JIS Z 0237 is preferably 500 (mN / 25 mm) or more and 6,000 (mN / 25 mm) or less, and 3,000 (mN / 25 mm) or more and 6,000 (mN). / 25 mm) or less is more preferable, and 4,000 (mN / 25 mm) or more and 6,000 (mN / 25 mm) or less is further preferable. When the adhesive strength is 500 (mN / 25 mm) or more and 6,000 (mN / 25 mm) or less, sufficient adhesiveness can be exhibited even on a flat surface made of dimethyl silicone.

The paper strength means the paper strength measured by the method shown below.

-Measuring method of paper strength-
The heat-sensitive recording medium before forming the adhesive layer was cut into a width of 25 mm and a length of 70 mm, humidity was controlled in an environment of a temperature of 23 ° C. and a relative humidity of 50%, and the heat-sensitive material was placed on a SUS substrate to which double-sided tape was completely attached. A 2 kg crimping roller was reciprocated once to bring 25 mm from one end of the label into close contact, and the label was allowed to stand in an environment having a temperature of 23 ° C. and a relative humidity of 50%. One end (one side) of the short axis of the heat-sensitive recording medium is folded back in the 180 ° direction, the other end (the other side) facing the heat-sensitive recording medium is fixed to the force gauge, and 180 at a speed of 300 ± 30 mm / min with respect to the substrate. The maximum load when the substrate was torn when pulled in the ° direction and peeled off was measured.

In the heat-sensitive recording medium of the present invention, since the value obtained by multiplying the adhesive strength by 3 is larger than the paper strength, the adhesive can be adhered without being easily peeled off even when the surface is adhered to a flat surface made of dimethyl silicone. It can be used as a heat-sensitive recording medium with excellent anti-tampering property because it is destroyed when it is peeled off.

The material of the adhesive layer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include silicone-based resin and acrylic-based resin. These may be used alone or in combination of two or more. Among these, silicone resin is preferable. When the material of the adhesive layer is a silicone resin, it is possible to obtain a sufficient adhesive force with a flat surface made of dimethyl silicone. The silicone-based resin is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a UV-curable silicone resin containing an organopolysiloxane having a hexenyl group.
As the pressure-sensitive adhesive for the pressure-sensitive adhesive layer, an appropriately synthesized adhesive may be used, or a commercially available product may be used. Examples of commercially available products of the acrylic resin include Oliveine BPW6111A (manufactured by Toyochem Co., Ltd.). Examples of commercially available products of the silicone-based resin include KR-3700 (manufactured by Shin-Etsu Silicone Co., Ltd.) and KR-3701 (manufactured by Shin-Etsu Silicone Co., Ltd.). These may be used alone or in combination of two or more.

The amount of the adhesive layer adhered after drying is not particularly limited and may be appropriately selected depending on the intended purpose. For example, 5 g / m ² or more and 30 g / m ² or less is preferable, and 10 g / m ² or more and 25 g. / M ² or less is more preferable, and 15 g / m ² or more and 20 g / m ² or less is particularly preferable.

The viscosity of the pressure-sensitive adhesive is not particularly limited and may be appropriately selected depending on the intended purpose. For example, 15,000 ± 5,000 mPa · s is preferable, and 15,000 ± 3,000 mPa · s is more preferable. .. When the viscosity of the pressure-sensitive adhesive is 15,000 ± 5,000 mPa · s, the coatability is excellent. If the viscosity of the pressure-sensitive adhesive is less than 10,000 mPas, bubbles are likely to be bitten during coating, and coating streaks are likely to appear. If it exceeds 20,000 mPas, the coating film surface becomes non-uniform, which affects the adhesive characteristics. There is a risk.

-Other ingredients-
The other components are not particularly limited and may be appropriately selected depending on the intended purpose, and the same components as those applicable to the adhesive layer can be used.

<Support>
The shape, structure, size, color tone, material, etc. of the support are not particularly limited and may be appropriately selected depending on the intended purpose. The shape may be, for example, a flat plate or a sheet. The structure may be a single-layer structure or a laminated structure, and the size may be appropriately selected depending on the size of the heat-sensitive recording medium and the like. ..
The material of the support is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include an inorganic material and an organic material.
Examples of the inorganic material include glass, quartz, silicone, silicone oxide, aluminum oxide, SiO ₂ , and metal.
Examples of the organic material include paper such as high-quality paper, art paper, coated paper, and synthetic paper; cellulose derivatives such as cellulose triacetate; polyester resins such as polyethylene terephthalate (PET) and polybutylene terephthalate, polycarbonate, polystyrene, and poly. Examples thereof include plastic films such as methyl methacrylate, polyethylene and polypropylene. These may be used alone or in combination of two or more.
For the purpose of improving the adhesiveness, the support is preferably surface-modified by, for example, corona discharge treatment, oxidation reaction treatment (chromic acid or the like), etching treatment, easy adhesion treatment, antistatic treatment or the like.
The average thickness of the support is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 20 μm or more and 2,000 μm or less, and more preferably 100 μm or more and 1,000 μm or less.

<Thermal recording layer>
The heat-sensitive recording layer contains a leuco dye, a color developer, and a binder resin, and further contains other components as needed.

-Leuco dye-
The leuco dye is not particularly limited and may be appropriately selected depending on the intended purpose. For example, leuco dyes such as triphenylmethane-based, fluorane-based, phenothiazine-based, auramine-based, spiropirane-based, and indrinovphthalide-based dyes can be appropriately selected. Examples include compounds. These may be used alone or in combination of two or more.

Examples of the leuco compound include 3,3-bis (p-dimethylaminophenyl) -phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone), 3. , 3-Bis (p-dimethylaminophenyl) -6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis (p-dibutylaminophenyl) phthalide, 3 -Cyclohexylamino-6-chlorofluorine, 3-dimethylamino-5,7-dimethylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8 -Benz Fluolane, 3-Diethylamino-6-Methyl-7-Chlorfluorane, 3- (N-p-Trill-N-Ethylamino) -6-Methyl-7-Anilinofluorane, 2- {N- (3'-Trifluolmethylphenyl) Amino} -6-diethylaminofluorane, 2- {3,6-bis (diethylamino) -9- (o-chloroanilino) lactam benzoate}, 3-diethylamino-6-methyl -7- (m-Trichloromethylanilino) fluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-di-n-butylamino- 7-o-Chloranilino) Fluoran, 3-N-methyl-N, n-amylamino-6-methyl-7-anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilino Fluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3- (N, N-diethylamino) -5-methyl-7- (N, N-dibenzylamino) fluorane, benzoyl leucomethylene blue, 6 '-Chloro-8'-Methyl-benzoindolino-spiropirane, 6'-bromo-3'-methoxy-benzoindolino-spiropirane, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- ( 2'-Methyl-5'chlorophenyl) phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-nitrophenyl) phthalide, 3- (2'- Hydroxy-4'-diethylaminophenyl) -3- (2'-methoxy-5'-methylphenyl) phthalide, 3- (2'-methoxy-4'-dimethylaminophenyl) Enyl) -3- (2'-hydroxy-4'-chlor-5'-methylphenyl) phthalide, 3- (N-ethyl-N-tetrahydrofurfuryl) amino-6-methyl-7-anilinofluorane, 3-N-Ethyl-N- (2-ethoxypropyl) amino-6-methyl-7-anilinofluorane, 3-N-methyl-N-isobutyl-6-methyl-7-anilinofluorane, 3- Morphorino-7- (N-propyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7- (N-benzyl-trifluoromethylani) Reno) fluorane, 3-pyrrolidino-7- (di-p-chlorophenyl) methylaminofluorane, 3-diethylamino-5-chloro-7- (α-phenylethylamino) fluorane, 3- (N-ethyl-p) -Truizino) -7- (α-phenylethylamino) fluorane, 3-diethylamino-7- (o-methoxycarbonylphenylamino) fluorane, 3-diethylamino-5-methyl-7- (α-phenylethylamino) fluorane, 3-Diethylamino-7-piperidinofluorane, 2-chloro-3- (N-methyltoluidino) -7- (pn-butylanilino) fluorane, 3-di-n-butylamino-6-methyl-7- Anilinofluorane, 3,6-bis (dimethylamino) fluorenspiro (9,3') -6'-dimethylaminophthalide, 3- (N-benzyl-N-cyclohexylamino) -5,6-benzo- 7-α-naphthylamino-4'-promofluorane, 3-diethylamino-6-chlor-7-anilinofluorane, 3-diethylamino-6-methyl-7-mesitidino-4', 5'-benzofluorane , 3-N-Methyl-N-isopropyl-6-methyl-7-anilinofluorane, 3-N-ethyl-N-isoamyl-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl -7- (2', 4'-dimethylanilino) fluorane, 3-diethylamino-5-chloro- (α-phenylethylamino) fluorane, 3-diethylamino-7-pyverizinofluorane, 3- (N-) Benzyl-N-cyclohexylamino) -5,6-benzo-7-α-naphthylamino-4'-bromofluorane, 3-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-7-anilinofuru Oran, 3-p- Dimethylaminophenyl) -3- {1,1-bis (p-dimethylaminophenyl) ethylene-2-yl} phthalide, 3- (p-dimethylaminophenyl) -3- {1,1-bis (p-dimethyl) Aminophenyl) ethylene-2-yl} -6-dimethylaminophthalide, 3- (p-dimethylaminophenyl) -3- (1-p-dimethylaminophenyl-1-phenylethylene-2-yl) phthalide, 3 -(P-Dimethylaminophenyl) -3- (1-p-dimethylaminophenyl-1-p-chlorophenylethylene-2-yl) -6-dimethylaminophthalide, 3- (4'-dimethylamino-2' -Methoxy) -3- (1 "-p-dimethylaminophenyl-1" -p-chlorophenyl-1 ", 3" -butadiene-4 "-yl) benzophthalide, 3- (4'-dimethylamino-2'- Benzyloxy) -3- (1 "-p-dimethylaminophenyl-1" -phenyl-1 ", 3" -butadiene-4 "-yl) benzophthalide, 3-dimethylamino-6-dimethylamino-fluoren-9- Spiro-3'-(6'-dimethylamino) phthalide, 3,3-bis (2- (p-dimethylaminophenyl) -2-p-methoxyphenyl) ethenyl) -4,5,6,7-tetrachloro Phenylide, 3-bis {1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl} -5,6-dichloro-4,7-dipromophthalide, bis (p-dimethylaminostyryl) -1-naphthalene Examples thereof include sulfonylmethane and bis (p-dimethylaminostyryl) -1-p-tolylsulfonylmethane.

The 50% cumulative volume particle diameter (D ₅₀ ) of the leuco dye is preferably 0.1 μm or more and 0.5 μm or less, and more preferably 0.1 μm or more and 0.4 μm or less.

The method for measuring the 50% cumulative volume particle size (D ₅₀ ) of the leuco dye is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a laser diffraction / scattering type particle size distribution measuring device ( Device name: LA-920, manufactured by Horiba Seisakusho Co., Ltd.) and the like.

The content of the leuco dye is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 5 parts by mass or more and 40 parts by mass or less, preferably 10 parts by mass, based on 100 parts by mass of the total amount of the heat-sensitive recording layer. More than 30 parts by mass is more preferable.

-Color developer-
As the color developer, various electron-accepting substances for reacting the leuco dye at the time of heating to develop a color can be applied.

The color developer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include phenolic substances, organic acidic substances, inorganic acidic substances, esters thereof, and salts thereof.

Examples of the color developer include carous acid, phenolic acid, 3-isopropylsalicylic acid, 3-cyclohexylsalicylic acid, 3,5-di-tert-butylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, 4 , 4'-isopropyridene diphenol, 1,1'-inopropyridenebis (2-chlorophenol), 4,4'-isopropyridenebis (2,6-dibromophenol), 4,4'-isopropyridenebis (2,6-dichlorophenol), 4,4'-isopropyridenebis (2-methylphenol), 4,4'-isopropyridenebis (2,6-dimethylphenol), 4,4-isopropyridenebis (2) -Tert-butylphenol), 4,4'-sec-butylidenediphenol, 4,4'-cyclohexylidenebisphenol, 4,4'-cyclohexylidenebis (2-methylphenol), 4-tert-butylphenol, 4 -Phenylphenol, 4-hydroxydiphenoxide, α-naphthol, β-naphthol, 3,5-xylenol, Timor, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, novolak-type phenolic resin, 2,2'-thiobis ( 4,6-dichlorophenol), catechol, resorcin, hydroquinone, pyrogallol, fluoroglycin, fluoroglycin carboxylic acid, 4-tert-octylcatechol, 2,2'-methylumbis (4-chlorophenol), 2,2'-methylumbis (4-Methyl-6-tert-butylphenol), 2,2,-dihydroxydiphenyl, 2,4'-dihydroxydiphenylsulfone, 4,4'-[oxybis (ethyleneoxy-P-phenylenesulfonyl)] diphenol, p. Ethyl-hydroxybenzoate, propyl p-hydroxybenzoate, butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, -p-chlorobenzyl p-hydroxybenzoate, -o-chlorobenzyl p-hydroxybenzoate, p -Hydroxybenzoic acid-p-methylbenzyl, p-hydroxybenzoic acid-n-octyl, benzoic acid, zinc salicylate, 1-hydroxy-2-naphthoic acid, 2-hydroxy-6-naphthoic acid, 2-hydroxy-6- Zinc naphthoate, 4-hydroxydiphenylsulfone, 4-hydroxy-4'-chlorodiphenylsulfone, bis (4-hydroxyphenyl) sulfide, 2-hydroxy-phenol Luic acid, zinc 3,5-di-tert-butyl salicylate, tin 3,5-di-tert-butyl salicylate, tartaric acid, oxalic acid, maleic acid, citric acid, succinic acid, stearic acid, 4-hydroxyphthalic acid, Boric acid, thiourea derivative, 4-hydroxythiophenol derivative, bis (4-hydroxyphenyl) acetic acid, bis (4-hydroxyphenyl) ethyl acetate, bis (4-hydroxyphenyl) n-propyl acetate, bis (4-hydroxy) Phenyl) m-butyl acetate, bis (4-hydroxyphenyl) phenyl acetate, bis (4-hydroxyphenyl) benzyl acetate, bis (4-hydroxyphenyl) phenethyl acetate, bis (3-methyl-4-hydroxyphenyl) acetate, Methyl bis (3-methyl-4-hydroxyphenyl) acetate, n-propyl bis (3-methyl-4-hydroxyphenyl) acetate, 1,7-bis (4-hydroxyphenylthio) 3,5-dioxaheptan, 1,5-bis (4-hydroxyphenylthio) 3-oxaheptane, dimethyl 4-hydroxyphthalate, 4-hydroxy-4'-methoxydiphenyl sulfone, 4-hydroxy-4'-ethoxydiphenyl sulfone, 4-hydroxy- 4'-Isopropoxydiphenyl sulfone, 4-hydroxy-4'-propoxydiphenyl sulfone, 4,4'-bis (3- (phenoxycarbonylamino) methylphenyl ureido) diphenyl 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'-benzyloxydiphenyl sulfone Hydroxy-4'-phenoxydiphenyl sulfone, 4-hydroxy-4'-(m-methylbenzyloxy) diphenyl sulfone, 4-hydroxy-4'-(p-methylbenzyloxy) diphenyl sulfone, 4-hydroxy-4'- Examples thereof include (O-methylbenzyloxy) diphenyl sulfone, 4-hydroxy-4'-(p-chlorobenzyloxy) diphenyl sulfone, and N- (2- (3-phenylureido) phenyl) benzene sulfone amide. These may be used alone or in combination of two or more.

The 50% cumulative volume particle diameter (D ₅₀ ) of the color developer is preferably 0.1 μm or more and 0.5 μm or less, and more preferably 0.1 μm or more and 0.4 μm or less.

The method for measuring the 50% cumulative volume particle size (D ₅₀ ) of the color developer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a laser diffraction / scattering type particle size distribution measuring device. (Device name: LA-920, manufactured by HORIBA, Ltd.) and the like.

The content of the color developer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.05 parts by mass or more and 10 parts by mass or less with respect to 1 part by mass of the leuco dye. More preferably, it is 1 part by mass or more and 5 parts by mass or less.

-Binder resin-
The binder resin is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a polyvinyl alcohol resin, a starch or a derivative thereof; a cellulose derivative such as hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose; Soda polyacrylic acid, polyvinylpyrrolidone, acrylamide-acrylic acid ester copolymer, acrylamide-acrylic acid ester-methacrylic acid ternary copolymer, styrene-maleic anhydride copolymer alkali salt, isobutylene-maleic anhydride copolymer Water-soluble polymers such as alkali salts, polyacrylamide, sodium alginate, gelatin, casein; polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylic acid ester, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, ethylene-acetate Examples thereof include emulsions such as vinyl copolymers, latexes such as styrene-butadiene copolymers and styrene-butadiene-acrylic copolymers, and styrene / butadiene copolymer latexs. These may be used alone or in combination of two or more. Among these, polyvinyl alcohol resin is preferable from the viewpoint of transparency and substrate binding.

-Other ingredients-
The other components are not particularly limited and may be appropriately selected depending on the intended purpose. For example, as a sensitivity improver, various heat-soluble substances, auxiliary additives, surfactants, lubricants, fillers, etc. Examples include ultraviolet absorbers and coloring pigments.

--Thermal soluble material ---
Examples of the heat-soluble substance include fatty acids such as stearic acid and bechenic acid; fatty acid amides such as stearic acid amide and partimate amide; zinc stearate, aluminum stearate, calcium stearate, zinc partimate and behen. Fatty metal salts such as zinc acid; p-benzylbiphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, phenyl β-naphthoate, phenyl1-hydroxy-2-naphthoate, Methyl 1-hydroxy-2-naphthoate, diphenyl carbonate, glycol carbonate, dibenzyl terephthalate, dimethyl terephthalate, 1,4-dimethoxynaphthalene, 1,4-diethoxynaphthalene, 1,4-dibenzyloxynaphthalene, 1, 2-Diphenoxyethane, 1,2-bis (3-methylphenoxy) ethane, 1,2-bis (4-methylphenoxy) ethane, 1,4-diphenoxy-2-butene, 1,2-bis (4-) Methoxyphenylthio) ethane, dibenzoylmethane, 1,4-diphenylthiobutane, 1,4-diphenylthio-2-butene, 1,3-bis (2-vinyloxyethoxy) benzene, 1,4-bis (2) -Vinyloxyethoxy) benzene, p- (2-vinyloxyethoxy) biphenyl, p-aryloxybiphenyl, p-propagiloxybiphenyl, dibenzoyloxymethane, dibenzoyloxypropane, dibenzyldisulfide, 1,1-diphenyl Ethanol, 1,1-diphenylpropanol, p-benzyloxybenzyl alcohol, 1,3-phenoxy-2-propanol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene, N-octadecylcarbamoylbenzene, 1,2-bis (4) −methoxyphenoxy) Propane, 1,5-bis (4-methoxyphenoxy) -3-oxapentane, dibenzyl oxalate, bis (4-methylbenzyl) oxalate, bis (4-chlorobenzyl) oxalate and the like. .. These may be used alone or in combination of two or more.

--Auxiliary additive ---
The auxiliary additive is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a hindered phenol compound and a hindered amine compound. These may be used alone or in combination of two or more.

Examples of the auxiliary additive include 2,2'-methylenebis (4-ethyl-6-terrary butylphenol), 4,4'-butylidenebis (6-terrific butyl-2-methylphenol), 1,1, and so on. 3-Tris (2-methyl-4-hydroxy-5-tershaly butylphenyl) butane, 1,1,3-Tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 4,4'-thiobis (6-Turricary Butyl-2-Methylphenol), Tetrabromobisphenol A, Tetrabromobisphenol S, 4,4 "thiobis (2-methylphenol), 4,4'-thiobis (2-chlorophenol), Tetrax ( 1,2,2,6,6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, tetrakis (1,2,2,6,6-tetramethyl-4-piperidyl)- 1,2,3,4-butanetetracarboxylate and the like can be mentioned. These may be used alone or in combination of two or more.

--Surfactant ---
The surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include anionic surfactants, nonionic surfactants, amphoteric surfactants and fluorine-based surfactants. Be done. These may be used alone or in combination of two or more.

Examples of the anionic surfactant include salts of polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, lauryl salt, and polyoxyethylene alkyl ether sulfate. These may be used alone or in combination of two or more.

Examples of the nonionic surfactant include acetylene glycol-based surfactants, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan fatty acid esters, and the like. These may be used alone or in combination of two or more.

Examples of the acetylene glycol-based surfactant include 2,4,7,9-tetramethyl-5-decine-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, and 3 , 5-Diol-1-hexin-3-diol, 2,5,8,11-tetramethyl-6-dodecine-5,8-diol and the like. These may be used alone or in combination of two or more.

--Glidant ---
The lubricant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a higher fatty acid or a metal salt thereof, a higher fatty acid amide, a higher fatty acid ester, an animal wax, a vegetable wax, a mineral wax, etc. Examples include petroleum wax. These may be used alone or in combination of two or more.

--Filler ---
Examples of the filler include 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. Inorganic fine powders such as urea-formalin resin, styrene-methacrylic acid copolymer, polystyrene resin, vinylidene chloride resin and the like. These may be used alone or in combination of two or more.

The content of the filler is not particularly limited and may be appropriately selected depending on the intended purpose, but is 0.5 parts by mass or more and 5.0 parts by mass or less with respect to 1 part by mass of the binder resin. It is preferable, and more preferably 1.0 part by mass or more and 4.0 parts by mass or less.

--UV absorber ---
The ultraviolet absorber is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include salicylic acid-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, and benzotriazole-based ultraviolet absorbers.

Examples of the ultraviolet absorber include phenyl salicylate, p-tert-butylphenyl salicylate, p-octylphenyl salicylate, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, and 2-hydroxy-4-octoxy. Benzophenone, 2-Hydroxy-4-dodecyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfo Benzophenone, bis (2-methoxy-4-hydroxy-5-benzoylphenyl) methane, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-5'-tert-butyl Phenyl) benzotriazole, 2- (2'-hydroxy-3', 5'-di-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3', 5'-di-tert-butylphenyl) Chlorobenzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3', 5'-di-tert- Amilphenyl) benzotriazole, 2- {2'-hydroxy-3'-(3 ", 4", 5 ", 6" -tetrahydrophthalimidemethyl) -5'-methylphenyl} benzotriazole, 2,2'-methylenebis {4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol}, 2- (2'-hydroxy-5'-metaacryloxyphenyl) -2H -Benzotriazole, 2- (3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole, 2- (2'-hydroxy-5'-t-octylphenyl) benzotriazole, 2- (5-methyl- 2-Hydroxyphenyl) benzotriazole and the like can be mentioned. These may be used alone or in combination of two or more.

--Coloring pigment ---
The coloring pigment is not particularly limited and may be appropriately selected depending on the intended purpose. For example, chromium yellow, iron oxide pigment, orange molybdenate, cadmium red, zinc sulfide compound, Hansa yellow, Hansa orange, and rose red. , Pyrazolone Red, Linol Red, Corpa Phthalocyanine Blue, Copal Polybrolo Phthalocyanine Blue, Industron Blue, Isodibenzatron Violet, Antantron Orange and the like. These may be used alone or in combination of two or more.

The method for forming the heat-sensitive recording layer is not particularly limited and may be appropriately selected depending on the intended purpose. As a method for forming the thermal recording layer, for example, the leuco dye and the color developer are pulverized and dispersed together with the binder resin by a disperser such as a ball mill, an attritor, or a sand mill, and then, if necessary, the other A method of preparing a coating liquid for a heat-sensitive recording layer by mixing with the above components and the like, applying the coating liquid for a heat-sensitive recording layer on the transparent base material, and then drying the coating liquid can be mentioned.

The coating method is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a blade coating method, a gravure coating method, a gravure offset coating method, a bar coating method, a roll coating method, a knife coating method, etc. Air knife coat method, comma coat method, U comma coat method, AKKU coat method, smoothing coat method, micro gravure coat method, reverse roll coat method, 4 or 5 roll coat method, dip coat method, curtain coat method, slide coat Examples include the method and the die coat method.

The 50% cumulative volume particle diameter (D ₅₀ ) of the coating liquid for the thermal recording layer is preferably 0.10 μm or more and 3 μm or less, more preferably 0.10 μm or more and 0.50 μm or less, and 0.10 μm or more and 0.40 μm or less. Especially preferable.

The amount of the heat-sensitive recording layer adhered after drying is not particularly limited and may be appropriately selected depending on the intended purpose. For example, 1.0 g / m ² or more and 20.0 g / m ² or less is preferable. .0g / ^m, more preferably ² or more 10.0 g / ^{m 2} or less, 2.0 g / ^{m 2} or more 4.0 g / ^{m 2} or less is particularly preferred.

As the heat-sensitive recording medium of the present invention, a heat-retaining layer, a heat-sensitive recording layer, a protective layer, and, if necessary, another layer can be provided on one surface of the support.

<Heat insulation layer>
The heat insulating layer is not particularly limited and may be appropriately selected depending on the intended purpose, but it preferably contains an adhesive resin, thermoplastic hollow resin particles and the like, and further contains other components as needed. .. In the following description, the heat insulating layer may be referred to as an undercoat layer.

The thermoplastic hollow resin particles have a thermoplastic resin as a shell and contain air or other gas inside, and are fine hollow particles that are already in a foamed state.

The average particle size (outer diameter of the particles) of the thermoplastic hollow resin particles is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.2 μm to 20 μm, more preferably 2 μm to 5 μm.
If the average particle size is smaller than 0.2 μm, it is technically difficult to make it hollow, and the role of the undercoat layer becomes insufficient. On the other hand, if the average particle size is larger than 20 μm, the smoothness of the surface after coating and drying is lowered, so that the coating of the heat-sensitive recording layer becomes non-uniform, and the coating liquid for the heat-sensitive recording layer is more than necessary for making the coating uniform. Must be applied.
Therefore, it is desirable that the average particle size is in the above range and the distribution peak is uniform with little variation.

The hollow ratio of the thermoplastic hollow resin particles is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 50% to 95%, more preferably 80% to 95%.
If the hollow ratio is less than 30%, the heat insulating property is insufficient, so that the thermal energy from the thermal head is released to the outside of the heat-sensitive recording medium through the support, and the sensitivity improving effect becomes insufficient. The hollow ratio referred to here is the ratio of the outer diameter and the inner diameter (diameter of the hollow portion) of the hollow particles, and is expressed by the following formula.
Hollow ratio (%) = (inner diameter of hollow particles / outer diameter of hollow particles) × 100

As described above, the thermoplastic hollow resin particles have a thermoplastic resin as a shell, but the thermoplastic resin is not particularly limited and may be appropriately selected depending on the intended purpose, for example. , Styrene-acrylic resin, polystyrene resin, acrylic resin, polyethylene resin, polypropylene resin, polyacetal resin, chlorinated polyether resin, polyvinyl chloride resin, copolymer resin mainly composed of vinylidene chloride and acrylonitrile, and the like. Among these, a styrene-acrylic resin and a copolymer resin mainly composed of vinylidene chloride and acrylonitrile are preferable because they have a high hollow ratio, a small variation in particle size, and are suitable for blade coating.

The thermoplastic substance is not particularly limited and may be appropriately selected depending on the intended purpose. However, phenol-formaldehyde resins, urea-formaldehyde resins, melamine-formaldehyde resins, furan resins and the like, and addition polymerization Examples thereof include unsaturated polyester resin and crosslinked MMA resin produced by.

The coating amount of the plastic hollow particles is not particularly limited and may be appropriately selected depending on the intended purpose, but 1 g to 3 g per 1 m2 of the support is required in terms of maintaining sensitivity and coating uniformity. If it is less than 1 g / m2, sufficient sensitivity cannot be obtained, and if it exceeds 3 g / m2, the bondability of the layer is lowered.

<Protective layer>
The protective layer preferably contains a binder and a pigment, more preferably a lubricant and a cross-linking agent, and further contains other components as necessary.

<< Binder >>
The binder is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include water-soluble resins, water-soluble resin emulsions, hydrophobic resins, ultraviolet curable resins, and electron beam curable resins. .. These may be used alone or in combination of two or more. Among these, a water-soluble resin is preferable from the viewpoint of head matching under low temperature and low humidity conditions.

Examples of the water-soluble resin include polyvinyl alcohol; modified polyvinyl alcohol; cellulose derivatives such as methyl cellulose, methoxy cellulose, and hydroxy cellulose; casein; gelatin; polyvinyl pyrrolidone; styrene / maleic anhydride copolymer; diisobutylene / maleic anhydride. Polymers; polyacrylamides; modified polyacrylamides; methylvinyl ether / maleic anhydride copolymers; carboquil-modified polyethylenes; polyvinyl alcohol / acrylamide block copolymers; melamine / formaldehyde resins; urea / formaldehyde resins and the like. These may be used alone or in combination of two or more. Among these, polyvinyl alcohol is preferable from the viewpoint of plasticizer resistance.

Examples of the water-soluble resin emulsion and the hydrophobic resin include polyvinyl acetate, polyurethane, styrene / butadiene copolymer, styrene / butadiene / acrylic copolymer, polyacrylic acid, polyacrylic acid ester, vinyl chloride / vinyl acetate. Examples thereof include copolymers, polybutyl methacrylate, polyvinyl butyral, polyvinyl acetal, ethyl cellulose, ethylene / vinyl acetate copolymers and the like. These may be used alone or in combination of two or more.

The average degree of polymerization of the binder is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 1,700 or more. When the average degree of polymerization of the binder is 1,700 or more, the plasticizer resistance and the head matching property under low temperature and low humidity conditions can be improved.
The average degree of polymerization of the binder can be measured by, for example, the test method specified in JIS K 6726.

<< Pigment >>
The pigment is not particularly limited and may be appropriately selected depending on the intended purpose. For example, aluminum hydroxide, calcium carbonate, kaolin, silica, zinc oxide, titanium oxide, zinc hydroxide, barium sulfate, clay, talc, surface. Inorganic fine powders such as treated calcium and silica; organic fine powders such as silicone resin particles, urea formalin resin, styrene / methacrylic acid copolymer, polystyrene resin, and polymethyl methacrylate resin can be mentioned. These may be used alone or in combination of two or more.

The content of the pigment is preferably 110 parts by mass or more, and preferably 110 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the binder. When the content of the pigment is 110 parts by mass or more with respect to 100 parts by mass of the binder, it is possible to suppress the transfer of the inorganic particles of the ink receiving layer to the surface of the protective layer even when stored in the roll form. ..

<< Lubricant >>
The lubricant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include polyethylene oxide wax, montan wax, zinc stearate and silicone wax. These may be used alone or in combination of two or more.

The lubricant can be used in combination with other known lubricants, if necessary, and other lubricants include, for example, candelilla wax, carnauba wax, rice wax, wood wax, jojoba oil and the like. Plant wax; Animal wax such as honey wax, lanolin, whale wax; Mineral wax such as ceresin and its derivatives; Petroleum wax such as paraffin, vaseline, microcrystan, petrolactum; Synthetic hydrocarbon such as Fisher Tropsch wax System wax; Hydrogenated wax such as hardened castor oil and cured castor oil derivative; Fatty acid such as stearate, oleic acid, erucic acid, lauric acid, sebacic acid, bechenic acid, palmitic acid; Amide such as adipic acid and isophthalic acid; Bisamides, esters, ketones, metal salts and derivatives thereof; examples thereof include alkyl-modified silicone resins and amide-modified silicone resins. These may be used alone or in combination of two or more.

<< Crosslinking agent >>
The cross-linking agent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples of the water-resistant agent for the water-soluble resin include polyamide epichlorohydrin resin and adipic acid dihydrazide. These may be used alone or in combination of two or more.

The method for forming the protective layer is not particularly limited and can be formed by a generally known method. For example, a pigment and a cross-linking agent are separately combined with a binder and other components in a ball mill, an attritor, and a sand mill. After pulverizing and dispersing until the dispersion particle size becomes 0.1 μm or more and 3 μm or less with a disperser such as Examples thereof include a method of forming a protective layer by applying it on top.

The coating amount of the protective layer coating solution, the dry weight is preferably 0.1 g / ^{m 2} or more 20 g / ^{m 2} or less, 0.5 g / ^{m 2} or more 10 g / ^{m 2} or less is more preferable. When the coating amount of the protective layer coating liquid is 0.1 g / m ² or more and 20 g / m ² or less, the plasticizer resistance and the head matching property in a low temperature and low humidity environment can be improved.

<Other layers>
The other layer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a back coat layer.

<< Back coat layer >>
The backcoat layer can be provided on the surface of the support on the side where the heat-sensitive recording layer is not provided, if necessary.
The backcoat layer contains a filler and a binder resin, and further contains other components such as a lubricant and a coloring pigment, if necessary.
As the filler, for example, an inorganic filler or an organic filler can be used.
Examples of the inorganic filler include carbonates, silicates, metal oxides, sulfuric acid compounds and the like.
Examples of the organic filler include silicone resin, cellulose, epoxy resin, nylon resin, phenol resin, polyurethane resin, urea resin, melamine resin, polyester resin, polycarbonate resin, styrene resin, acrylic resin, polyethylene resin, formaldehyde resin, and poly. Examples thereof include methyl methacrylate resin.
The binder resin is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the same binder resin as the heat-sensitive recording layer can be used.
The average thickness of the backcoat layer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.1 μm or more and 20 μm or less, and more preferably 0.3 μm or more and 10 μm or less.

The mode of the heat-sensitive recording medium of the present invention is not particularly limited, and can be appropriately selected depending on the intended purpose. For example, it may be used as a label as it is, or a layer for printing information such as a character, a mark, a picture, a barcode or a two-dimensional code such as a QR code (registered trademark) may be provided on the protective layer or the support. Good.

The mode of the heat-sensitive recording medium of the present invention is not particularly limited and may be appropriately selected depending on the intended purpose. For example, by laminating a release paper on the adhesive layer, a sticker-type heat-sensitive recording medium can be used. It may also be used as a thermal recording label.
The release paper is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include acid-free paper, acid paper, plastic and the like bonded to each other. Further, a standard illustration such as a color-displayed logo or a standard sentence may be printed on the side opposite to the heat-sensitive recording layer forming side of the transparent base material by a printing method such as an inkjet or an offset.
The shape of the heat-sensitive recording medium of the present invention is not particularly limited and may be appropriately selected depending on the intended purpose. For example, it may be in the form of a label, a sheet, a roll, or the like, and further, a transparent base material. A linerless type in which a release layer is formed on the roll and wound in a roll shape can be obtained.

The heat-sensitive recording medium of the present invention may be provided with perforations for preventing re-covering. This perforation reduces the paper strength of the perforated portion, so that the label itself is easily destroyed when it is attempted to be peeled off from the adherend. The shape of the perforation is not particularly limited and can be appropriately selected according to the purpose.
The perforation needs to have one uncut portion length of 1.5 mm or less and a cut portion length of twice or more the uncut portion length, more preferably 3 to 10 times. The range is preferred.
The structure of the thermal recording linerless label is not particularly limited and may be appropriately selected, and examples thereof include a roll shape, a sheet shape, and a film shape. Among these, the roll shape is preferable from the viewpoint of convenience.
The heat-sensitive recording medium of the present invention can be processed into any size and used. For example, the heat-sensitive recording medium of the present invention provided in the form of a roll can be used as a markdown label for displaying the price of food by cutting it into a length of 40 mm and a width of 50 mm.
The surface portion of the heat-sensitive recording medium of the present invention can be colored in any pattern according to the purpose. For example, by coloring the bar code display unit and the price reduction rate display unit in white and the color around the information display unit in red, it is possible to appeal to consumers visually more strongly.

Here, FIG. 1 is a diagram showing an example of the heat-sensitive recording medium of the present invention. As shown in FIG. 1, the heat-sensitive recording medium 1 of the present invention is provided with the heat-sensitive recording layer 12 and the barrier layer 11 on the base material 13. Further, the adhesive layer 14 is provided on the base material 13 on the opposite side of the thermal recording layer 12. Further, as shown in FIG. 2, a release paper 15 can be provided on the adhesive layer 14. Further, as shown in FIG. 3, a layer structure in which the release layer 16 is provided on the barrier layer 11 can be used.

(Manufacturing method of thermal recording medium)
The method for producing a heat-sensitive recording medium of the present invention includes a step of forming a heat-sensitive recording layer on a support and a step of forming a pressure-sensitive adhesive layer containing a silicone-based pressure-sensitive adhesive on the support, and further necessary. Other steps are included accordingly.

<Step of forming a thermal recording layer>
The step of forming the heat-sensitive recording layer is not particularly limited and may be appropriately selected depending on the intended purpose, and the same step as the above-mentioned method of forming the heat-sensitive recording layer can be used.

On the surface of the support on which the heat-sensitive recording layer is formed, corona discharge treatment, oxidation reaction treatment (chromic acid, etc.), etching treatment, easy-adhesion treatment, antistatic treatment, etc. are performed before the coating liquid for the heat-sensitive recording layer is applied. It is preferable to carry out the surface modification treatment of. Thereby, the adhesiveness between the support and the heat-sensitive recording layer can be improved. In addition to these surface modification treatments, for example, a layer containing a styrene-butadiene polymer (easy-adhesive layer) is formed on a transparent base material, and then heat-sensitive on the layer containing the styrene-butadiene polymer. The film peeling can be prevented by forming the recording layer.

<Step of forming an adhesive layer>
As a step of forming the adhesive layer, a conventionally used forming method can be used. For example, the adhesive is applied onto the support by a coating method such as a bar coating method, a roll coating method, a comma coating method, or a gravure coating method. An adhesive layer can be formed by applying to and then drying.

<Other processes>
As the other step, for example, in the case of using a sticker type thermal recording medium, it is preferable to attach a release paper on the adhesive layer. The method of laminating the release paper is not particularly limited, and a generally used method can be used.
When using a linerless type heat-sensitive recording medium, a coating liquid for a release layer is applied to the side opposite to the heat-sensitive recording layer forming side of the transparent substrate. As a method of applying the coating liquid for the release layer, the same method as the method of applying the coating liquid for the thermal recording layer described above can be used.
(Recording method)
The recording method using the heat-sensitive recording medium of the present invention is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a thermal head and a laser.
The shape, structure, size, and the like of the thermal head are not particularly limited, and can be appropriately selected depending on the intended purpose.
The laser is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a CO ₂ laser having a wavelength of 9.3 μm or more and 10.6 μm or less, a semiconductor laser and the like.

(Use)
Since the heat-sensitive recording medium of the present invention has high color development sensitivity and image density, and has excellent hand cream resistance, for example, POS fields such as fresh foods, lunch boxes, and prepared foods; books, documents, etc. Copying field; Communication field such as facsimile; Ticketing field such as ticket vending machine, receipt, receipt; It can be used in various fields such as baggage tags, pill cases, and pill bottles in the aircraft industry.

(Article)
The article has the thermal recording medium of the present invention.

As the heat-sensitive recording medium, the heat-sensitive recording medium of the present invention can be preferably used.

Having the heat-sensitive recording medium of the present invention means a state in which the heat-sensitive recording medium of the present invention is attached, attached, or the like.

The article of the present invention is not particularly limited as long as it has the thermal recording medium of the present invention, and can be appropriately selected depending on the intended purpose. Examples thereof include packing materials, packaging materials, and wrapping paper. In particular, articles that require high solvent resistance can be mentioned.

Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Example 1)
[Preparation of heat insulating layer forming liquid]
-Micro hollow particles (hollow ratio 50%) 36 parts by mass-Styrene / butadiene copolymer latex (solid content concentration 47.5%) 10 parts by mass-54 parts by mass of water The above mixture is stirred and dispersed to provide a heat insulating layer (undercoat). Layer) Forming solution was prepared.

[Adjustment of thermal recording layer forming liquid]
First, C-Stoff was prepared from C-Stoff shown below.

<Liquid A (electron donating dye dispersion)>
20 parts by mass of 3-dibutylamino-6-methyl-N-7-anilinofluorane ・ 20 parts by mass of 10% aqueous solution of polyvinyl alcohol ・ 60 parts by mass of water The above mixture was pulverized in a magnetic ball mill for 2 days to donate electrons. A sex dye dispersion was prepared.

<Liquid B (color developer dispersion)>
・ 4-Isopropoxy-4'-hydroxydiphenylsulfone 20 parts by mass ・ 10% aqueous solution of polyvinyl alcohol 25 parts by mass ・ 50 parts by mass of water The above mixture was pulverized in a magnetic ball mill for 2 days to prepare a developer dispersion. ..

<Liquid C (filler dispersion)>
20 parts by mass of silica ・ 5% aqueous solution of methyl cellulose 20 parts by mass ・ 50 parts by mass of water The above mixture was pulverized in a magnetic ball mill for 2 days to prepare a filler dispersion.

Next, 15 parts by mass of the electron-donating dye dispersion, 45 parts by mass of the developer dispersion, 45 parts by mass of the filler dispersion, and 5 parts by mass of a 20% alkaline aqueous solution of the isobutylene / maleic anhydride copolymer. The heat-sensitive recording layer forming liquid 1 was prepared by stirring the mixed liquid consisting of the parts.

[Preparation of protective layer forming liquid]
-Aluminum hydroxide 20 parts by mass-10% aqueous solution of polyvinyl alcohol 20 parts by mass-Water 60 parts by mass The above mixture was pulverized in a magnetic ball mill for 2 days to prepare a protective layer forming liquid.

[Preparation of back layer forming liquid]
30 parts by mass of calcined kaolin ・ 10% aqueous solution of polyvinyl alcohol 20 parts by mass ・ 50 parts by mass of water The above mixture was pulverized in a magnetic ball mill for 2 days to prepare a protective layer forming liquid.

Next, a commercially available high-quality paper (basis weight 35 g, thickness: 50 μm) is coated with a liquid A: heat insulating layer (undercoat layer) forming liquid so that the amount of dry adhesion is 3.0 g / m ^2. The heat-sensitive recording layer forming liquid 1 is applied and dried so that the dry adhesion amount of the dye is 0.35 g / m ² , and the dry adhesion amount of the resin is 1.6 g / m ² on the coating and drying. A protective layer (overcoat layer) forming liquid is applied to the back surface of the support, and a back layer is applied to the back surface of the support so that the amount of dry adhesion of the resin is 0.7 g / m ^2. After that, the heat-sensitive recording medium is subjected to a calendar. I got 1.

Next, an acrylic pressure-sensitive adhesive (product name: Oliveine BPW6111A, manufactured by Toyochem Co., Ltd.) was applied to the surface of the release paper so that the amount of adhesion after drying was 20 g / m ^2, and then the heat-sensitive recording medium 1 obtained. An adhesive layer was formed by laminating with the support side to obtain a heat-sensitive label 1.

(Example 2)
In Example 1, instead of using an acrylic pressure-sensitive adhesive for the pressure-sensitive adhesive layer, a silicone-based pressure-sensitive adhesive (product name: KR-3700, Shin-Etsu Silicone Co., Ltd.) is used, and no perforation is provided when evaluating the label breaking style described later. A heat-sensitive label 2 was obtained in the same manner as in Example 1.

(Example 3)
In Example 1, instead of using an acrylic pressure-sensitive adhesive for the pressure-sensitive adhesive layer, a silicone-based pressure-sensitive adhesive (product name: KR-3701, Shin-Etsu Silicone Co., Ltd.) is used, and no perforation is provided when evaluating the label breaking style described later. Except for this, a thermal label 3 was obtained in the same manner as in Example 1.

(Example 4)
In Example 1, instead of using an acrylic pressure-sensitive adhesive for the pressure-sensitive adhesive layer, a silicone-based pressure-sensitive adhesive (product name: KR-3700, Shin-Etsu Silicone Co., Ltd.) was used, which was twice the connection length when evaluating the label breaking style. A heat-sensitive label 4 was obtained in the same manner as in Example 1 except that a perforation having a length of 1 was provided.

(Example 5)
In Example 1, the hollow ratio of the fine hollow particles in the heat insulating layer forming liquid is 80%, and instead of using an acrylic adhesive for the adhesive layer, a silicone adhesive (product name: KR-3700, Shinetsu Silicone Co., Ltd.) ) Was used to obtain a heat-sensitive label 5 in the same manner as in Example 1 except that no perforation was provided when evaluating the label breaking style.

(Example 6)
In Example 1, the hollow ratio of the fine hollow particles in the heat insulating layer forming liquid is 90%, and instead of using an acrylic adhesive for the adhesive layer, a silicone adhesive (product name: KR-3700, Shinetsu Silicone Co., Ltd.) ) Was used to obtain a thermal label 6 in the same manner as in Example 1 except that no perforation was provided when evaluating the label breaking style.

(Example 7)
In Example 1, the hollow ratio of the fine hollow particles in the heat insulating layer forming liquid is 93%, and instead of using an acrylic adhesive for the adhesive layer, a silicone adhesive (product name: KR-3700, Shinetsu Silicone Co., Ltd.) ) Was used to obtain a thermal label 7 in the same manner as in Example 1 except that no perforation was provided when evaluating the label breaking style.

(Example 8)
In Example 1, the hollow ratio of the fine hollow particles in the heat insulating layer forming liquid is 90%, and instead of using an acrylic adhesive for the adhesive layer, a silicone adhesive (product name: KR-3700, Shinetsu Silicone Co., Ltd.) ) Was used to obtain a thermal label 8 in the same manner as in Example 1 except that a perforation having a length twice as long as the connection length was provided at the time of evaluating the label breaking style.

(Comparative Example 1)
In Example 1, a thermal label 9 was obtained in the same manner as in Example 1 except that no perforation was provided when evaluating the label breaking style.

(Comparative Example 2)
In Example 1, a commercially available high-quality paper (basis weight 120 g, thickness: 150 μm) is used as a support, and instead of using an acrylic adhesive for the adhesive layer, a silicone adhesive (product name: KR-3700, Shinetsu Silicone) is used. A heat-sensitive label 10 was obtained in the same manner as in Example 1 except that no perforation was provided when evaluating the label breaking style.

Next, using the heat-sensitive labels of Examples 1 to 8 and Comparative Examples 1 and 2, "adhesive strength", "paper strength", "label breaking style", "sensitivity", and "color development" are as follows. "Concentration" was evaluated. The results are shown in Table 1 below.

[Adhesive strength]
Used for thermal recording medium (thermal label) 25 μm synthetic paper coated with almost the same amount of adhesive was cut out to a width of 25 mm and a length of 70 mm, and 25 mm from one end was pasted on an aluminum substrate. A 2 kg crimping roller was reciprocated once on a flat surface made of silicone to bring it into close contact, and allowed to stand at a temperature of 23 ° C. and a relative humidity of 50% for 24 hours. One end (one side) of the short axis of the thermal recording is folded back in the 180 ° direction, and the other end (the other side) facing the heat sensitive recording is fixed to the force gauge in the 180 ° direction at a speed of 300 ± 30 mm / min with respect to the substrate. The weight when it was pulled and peeled off was measured. This was used as a reference value for the heat-sensitive recording material and the adherend (linerless label).

[Paper strength]
The heat-sensitive recording medium before forming the adhesive layer was cut into a width of 25 mm and a length of 70 mm, humidity was controlled in an environment of a temperature of 23 ° C. and a relative humidity of 50%, and the double-sided tape was completely attached onto the stainless steel substrate. A 2 kg roller was reciprocated once from one end of the heat-sensitive label to bring it into close contact with the label, and the label was allowed to stand in an environment having a temperature of 23 ° C. and a humidity of 50%. One end (one side) of the short axis of the heat-sensitive recording medium is folded back in the 180 ° direction, the other end (the other side) facing the heat-sensitive recording medium is fixed to the force gauge, and 180 at a speed of 300 ± 30 mm / min with respect to the substrate. The maximum load when the base material was torn when it was pulled off in the degree direction was measured.

[Label breaking style]
The heat-sensitive label was cut into a width of 25 mm and a length of 70 mm, and the humidity was controlled in an environment of 22 ° C. and 50% RH to prepare a test sample. A perforation having a cut portion length of 5 times that of the uncut portion length was provided in the central portion of the sample in order to prevent unauthorized replacement (Examples 2 to 3, 5 to 7 and Comparative Example 1). Not provided in ~ 2). Next, the roller is reciprocated once on the (linerless label) to adhere to the adherend having 25 mm from one end in the long axis direction of the label on the aluminum substrate, and the label is not attached to the aluminum substrate. When the other end of the heat-sensitive label was pulled from the substrate at a speed of 300 ± 30 mm / min in the 180 ° direction and peeled off, the fracture mode of each heat-sensitive label was observed and evaluated according to the following criteria.

[Evaluation criteria]
⊚: At least one layer including the support of the heat-sensitive recording medium remains on the base material in an amount of 80% or more. 〇: At least one layer including the support of the heat-sensitive recording medium remains on the base material in an amount of 30 to 80% or more. Remaining Δ: At least one layer including the support of the heat-sensitive recording medium remains in an amount of 30% or less ×: Any layer of the heat-sensitive recording medium is peeled off from the adherend without being torn.

(sensitivity)
Each heat-sensitive label is printed with a print simulator (manufactured by Okura Electric Co., Ltd.) under the conditions of head power 0.45 w / dot, 1-line recording time 20 ms / line, and scanning line density 8 x 3.85 dots / mm. Printing was performed at 0.2 ms to 1.2 ms, and the print density was measured with a Macbeth reflection densitometer RD-914 (manufactured by Macbeth).
At this time, the energy value required to obtain the image density of 1.0 was calculated, and the sensitivity magnification when the sample of Comparative Example 1 was used as a reference was calculated from the energy value according to the following mathematical formula.
The larger the value of this sensitivity magnification, the better the color development sensitivity (thermal responsiveness).
Sensitivity magnification = (energy value of Comparative Example 1) / (energy value of measured sample)

(Color density)
Each heat-sensitive label was subjected to the conditions of 120 ° C., 130 ° C., 140 ° C., 150 ° C., 160 ° C., 170 ° C., 180 ° C., and 190 ° C. using a thermal gradient tester (HEAT GRADINIT, manufactured by Toyo Seiki Co., Ltd.). The image density of each color was measured with a Macbeth reflection densitometer RD-914 (manufactured by Macbeth), and the highest density was recorded.

As shown in Table 1, in Examples 4 and 8 in which "paper strength <adhesive strength", most of the labels remain on the substrate (mainly interlayer breakage) and sufficiently function as a markdown label. It turned out.
Further, it was found that when the paper strength / adhesive strength> 3, the label was broken so as to be torn and functioned as a price reduction label (markdown label).
On the other hand, it was found that when the paper strength greatly exceeded the adhesive strength, the label was completely peeled off and did not function.

Examples of aspects of the present invention are as follows.
<1> A heat-sensitive recording medium having at least an adhesive layer, a support, and a heat-sensitive recording layer.
It is a heat-sensitive recording medium characterized in that the surface is adhered to a flat surface made of dimethyl silicone and then torn when attempted to be peeled off.
<2> The value three times the adhesive strength (mN / 25 mm) of the thermal recording medium measured by adhering the surface to a flat surface made of dimethyl silicone is larger than the paper strength (mN / 25 mm) of the thermal recording medium. It is a heat-sensitive recording medium characterized by being large.
<3> The heat-sensitive recording medium according to any one of <1> to <2>, wherein the pressure-sensitive adhesive layer contains a silicone-based pressure-sensitive adhesive.
<4> The heat-sensitive recording medium according to <3>, wherein the silicone-based pressure-sensitive adhesive is a UV-curable silicone resin containing an organopolysiloxane having a hexenyl group.
<5> The heat-sensitive recording medium according to any one of <1> to <4>, wherein the adhesive layer has an adhesive strength of 500 (mN / 25 mm) or more measured by JIS Z 0237.
<6> The heat-sensitive recording medium according to any one of <1> to <5>, which has a perforated cut.
<7> The heat-sensitive recording medium according to any one of <1> to <6>, which has hollow particles between the support and the heat-sensitive recording layer.
<8> The heat-sensitive recording medium according to <7>, wherein the average hollow ratio of the hollow particles is 50% or more and 95% or less.
<9> The heat-sensitive recording medium according to any one of <7> to <8>, which is a re-covering label.
<10> The heat-sensitive recording medium according to any one of <1> to <9>, which is wound in a roll shape.
<11> The process of forming a heat-sensitive recording layer on the support and
A method for producing a heat-sensitive recording medium, which comprises a step of forming a pressure-sensitive adhesive layer containing a silicone-based pressure-sensitive adhesive on the heat-sensitive recording layer.

According to the method for producing the heat-sensitive recording medium according to any one of <1> to <10> and the heat-sensitive recording medium according to <11>, the conventional problems are solved and the object of the present invention is achieved. Can be achieved.

Japanese Unexamined Patent Publication No. 2001-082876 Japanese Unexamined Patent Publication No. 2013-195889

1 Thermal recording medium 11 Barrier layer 12 Thermal recording layer 13 Base material 14 Adhesive layer 15 Release paper 16 Release layer

Claims (11)

A heat-sensitive recording medium having at least an adhesive layer, a support, and a heat-sensitive recording layer.
A heat-sensitive recording medium characterized in that the surface is adhered to a flat surface made of dimethyl silicone and then torn when attempted to be peeled off. A claim that a value three times the adhesive strength (mN / 25 mm) of the thermal recording medium measured by adhering the surface to a flat surface made of dimethyl silicone is larger than the paper strength (mN / 25 mm) of the thermal recording medium. The heat-sensitive recording medium according to 1. The heat-sensitive recording medium according to any one of claims 1 to 2, wherein the pressure-sensitive adhesive layer contains a silicone-based pressure-sensitive adhesive. The heat-sensitive recording medium according to claim 3, wherein the silicone-based pressure-sensitive adhesive is a UV-curable silicone resin containing an organopolysiloxane having a hexenyl group. The heat-sensitive recording medium according to any one of claims 1 to 4, wherein the adhesive layer has an adhesive strength measured by JIS Z 0237 of 3000 (mN / 25 mm) or more. The heat-sensitive recording medium according to any one of claims 1 to 5, which has perforated cuts. The heat-sensitive recording medium according to any one of claims 1 to 6, which has hollow particles between the support and the heat-sensitive recording layer. The heat-sensitive recording medium according to claim 7, wherein the average hollow ratio of the hollow particles is 50% or more and 95% or less. The heat-sensitive recording medium according to any one of claims 1 to 8, which is a label for re-covering. The heat-sensitive recording medium according to any one of claims 1 to 9, which is wound in a roll shape. The process of forming a thermal recording layer on the support and
A method for producing a heat-sensitive recording medium, which comprises a step of forming a pressure-sensitive adhesive layer containing a silicone-based pressure-sensitive adhesive on the heat-sensitive recording layer.

Images