JPH04263988A - Thermal recording medium - Google Patents

Abstract

PURPOSE:To obtain a thermal recording medium which has excellent resistance against oil and water and high PVC wrapping properties, and further can be used as a thermal label. CONSTITUTION:A thermal recording consists of a thermal color developer composition obtained by adding an oil repellent of an organic compound containing fluorine to a thermal coloring agent based on leuco dye, organic acid material and an adhesive, applied to a support. A recorded image no longer becomes discharged, if a plasticiser or oil permeates a thermal recording medium processed into a 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 material, and more specifically, it relates to a heat-sensitive recording material having excellent oil resistance, water resistance, and vinyl chloride wrap resistance for use in heat-sensitive labels and the like.

0002

BACKGROUND OF THE INVENTION Heat-sensitive recording materials are generally made of paper, synthetic paper, plastic film, etc. on one side of a support.
A heat-sensitive color-forming layer containing as main components a colorless or light-colored color-forming substance such as an electron-donating leuco dye, an organic acidic substance (color developer) such as an electron-accepting phenolic compound, and an adhesive. A color-forming recorded image can be obtained by causing these color-forming dyes and a color developer to react with each other using thermal energy.

[0003] Such heat-sensitive recording media has the advantages that the recording device is compact, inexpensive, and easy to maintain, and is used only as a recording medium for facsimile machines, automatic ticket vending machines, and scientific measuring instruments. Not POS label, C
It is widely used in various printers and plotters for AD, CRT medical images, etc.

However, conventional heat-sensitive recording materials have a problem in that when they come into contact with oil or plasticizer, the recording density decreases, or in severe cases, the recording disappears altogether. For example, when a heat-sensitive label with a pressure-sensitive adhesive (adhesive) layer provided on the back side of a heat-sensitive recording material is attached to a PVC film, polypropylene film, etc. as a POS label, the plasticizer contained in the film is released from the back side of the label. There was a problem that the plasticizer migrated from the film that came into direct contact with the label surface, making the barcode and characters printed on the label unreadable. Further, even if oils such as edible oils and industrial oils come into contact with the heat-sensitive label attached to the film, there is a problem in that the recording part disappears or becomes illegible, similar to the case with plasticizers.

In order to solve this problem, an attempt was made to provide an overcoat layer on the surface of the heat-sensitive layer (Japanese Utility Model Publication No. 59-9909).
Publication of Utility Model Publication No. 62-26217, Japanese Utility Model Publication No. 62-26
No. 218), and some improvement was seen. However, especially when a large amount of oil is in contact with the support for a long period of time, there is a problem in that the oil permeates through the cut cross section of the support, reaches the coloring part of the heat-sensitive layer, and decolors the coloring part.

[0006]

[Problems to be Solved by the Invention] The present invention prevents the transfer of plasticizer from the front and back surfaces of the heat-sensitive recording material, and furthermore, prevents the decolorization of the heat-sensitive recording area even if oil penetrates from the cross section of the support. The purpose is to prevent

[0007]

[Means for Solving the Problems] The present inventors have discovered that not only the heat-sensitive recording material does not discolor even when it comes into contact with a film containing a plasticizer, but also that the heat-sensitive recording material is immersed in oil, and the cut and back surfaces of the heat-sensitive recording material are As a result of research into ways to improve oil resistance so that records on a heat-sensitive recording medium do not fade even when oil comes into contact with them, the present invention has been completed.

[0008] The present invention provides a heat-sensitive material containing, as main components, a colorless or light-colored electron-donating leuco dye, a color developer that develops color from the leuco dye by heating, a thermofusible substance, and an adhesive on one side of the support. In a heat-sensitive recording material provided with a color-forming layer and, if necessary, an overcoat layer containing a water-soluble resin, a crosslinking agent, and a pigment as main components on the heat-sensitive color-forming layer, the heat-sensitive color-forming layer contains an oil repellent. Even if a heat-sensitive label with barcodes and characters printed on it using a label printer was immersed in oil at room temperature for two days, the printed area could be improved to a level that made it sufficiently readable.

The mechanism by which oil resistance is improved by including an oil repellent in the heat-sensitive coloring layer is unclear, but the color-forming dye, color developer, and thermofusible substance are eutectic during heating. If an oil repellent is present around the dye-developer-thermofusible substance combination that has developed a color after cooling, even if oil or plasticizer comes into contact with it, a part of the combination will be exposed to the oil or plasticizer. This is thought to be due to the fact that there are parts that do not get wet and do not fade.

[0010] The oil repellent may be mixed with the heat-sensitive coloring layer paint, or may be further mixed with a dispersion of one or more of color-forming dyes, color developers, and thermofusible substances, which are component particles of the heat-sensitive coloring layer. It is desirable to mix the substances when dispersing them and to adsorb them onto the surfaces of the dispersion particles.

Color-forming dyes, color developers, and thermofusible substances are usually supplied in the form of powder, so they are mixed with water and processed in a ball mill.
It is used after being ground to a particle size of 0.1 to 10 μm using a dispersing machine such as a sand grinder, attritor, Ultra Visco Mill, Dyno Mill, etc. During this operation, an oil repellent is added,
Furthermore, in order to increase the dispersion efficiency and improve the stability of the dispersion, it is desirable to use a dispersant, a water-soluble resin, or an antifoaming agent in combination.

As an oil repellent, for example, fluoroalkyl (
C2-C20) carboxylic acid, perfluoroalkyl (C
7-C13) carboxylic acid, 3-{fluoroalkyl (C
6-C11) Sodium oxy}-1-alkyl (C3-C4) sulfonate, sodium 3-{ω-fluoroalkanoyl (C6-C8)-N-ethylamino}-1-propanesulfonate, N-{3- (perfluorooctanesulfonamido)propyl}-N,N-dimethyl-N
-Carboxymethylene ammonium betaine, perfluoroalkyl (C4-C12) carboxylic acid alkali metal salt, perfluorooctane sulfonic acid diethanolamide, perfluoroalkyl (C6-C10) sulfonamidopropyl trimethylammonium salt, perfluoroalkyl (C6-C10) )-N-ethylsulfonylglycine salt, N-perfluorooctanesulfonylglutamate disodium, N-propyl-N-(2-hydroxyethyl)perfluorooctanesulfonamide, N-
{3-(perfluorooctanesulfonamido)propyl}-N,N-dimethyl-N-carboxymethylene ammonium betaine, bis(N-perfluorooctylsulfonyl-N-ethylaminoethyl) phosphate, monoperfluoroalkyl (C6 -C16) Surfactants such as ethyl phosphate esters, perfluoroalkyl (C4-C12) ammonium phosphates, and polymeric compounds containing these fluorine-containing moieties in their molecular structures.

[0013] The amount of oil repellent added is 10% of the solid content of the heat-sensitive coloring layer.
It is desirable to add 0.1 to 10 parts per 0 parts. 0.
If the amount is less than 1 part, the oil repellency is insufficient, and if it exceeds 10 parts, there are drawbacks such as poor coating properties of the overcoat layer applied on the heat-sensitive coloring layer and increased cost. As the color-forming dye, a colorless or light-colored electron-donating dye that can develop color by reacting with a color developer under heating is used.

Color-forming dyes used in the present invention include:
For example, 2,2bis{4-(6'-(N-cyclohexyl-N-methylamino)-3'-methylspiro[phthalido-3,9'-xanthene]-2'-ylamido]phenyl}propane, 3- diethylamino-6-methyl-7
-anilinofluorane, 3-piperidino-6-methyl-
7-anilinofluorane, 3-(N-ethyl-N-cyclohexylamino)-6-methyl-7-anilinofluorane, 3-diethylamino-7-chloroanilinofluorane, 3-[N-ethyl- N-(p-methylphenyl)
Amino]-6-methyl-7-anilinofluorane, 3-
Diethylamino-7-(metatrifluoromethyl)anilinofluorane, 3-[N-ethyl-N-tetrahydrofurfuryl]amino-6-methyl-7-anilinofluorane, 3-[N-ethyl-N- isopentyl]amino-
Examples include those consisting of at least one member of fluoran dyes such as 6-methyl-7-anilinofluorane and 3-[N,N dibutyl]amino-6-methyl-7-anilinofluorane.

The color developer used in the present invention is composed of an electron-accepting organic acidic substance capable of reacting with a color-forming dye under heating to develop color. Such a color developer liquefies or vaporizes at room temperature or higher, preferably 70° C. or higher, and reacts with the color-forming dye to develop color.

Examples of the color developer used in the present invention include 4,4'-isopropylidene diphenol (bisphenol A), 4,4'-isopropylidene bis(2-
chlorophenol), 4,4'-isopropylidene bis(2-methylphenol), 4,4'-isopropylidene bis(2,6-tert-butylphenol), 4,
4'-sec-butylidene diphenol, 4,4'-cyclohexylidene diphenol, 4-tert-butylphenol, 4-phenylphenol, 4-hydroxydiphenoxide, naphthol, β-naphthol, methyl-4-hydroxybenzoate, 4 -Hydroxy-acetophenone, salicylic acid anilide, novolac type phenolic resin, halogenated novolac type phenolic resin, 4
, 4'-thiobis(3-methyl-6-tert-butylphenol), propyl p-hydroxybenzoate, p-
Aliphatic carboxylic acids such as isopropyl hydroxybenzoate, butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, methylbenzyl p-hydroxybenzoate, oxalic acid, maleic acid, tartaric acid, citric acid, succinic acid, stearic acid, Benzoic acid, p-tert-butylbenzoic acid, phthalic acid, gallic acid, salicylic acid, 3-isopropylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, bis(4-hydroxyphenyl) sulfide,
1,7-di(4-hydroxyphenylthio)-3,5-
Dioxaheptane, p-nitrobenzoic acid, salts of these organic color developers with polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, nickel, 4,4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenyl sulfone, 3,3
'-dihydroxydiphenylsulfone, 3,3'-diamino-4,4'-dihydroxy-diphenylsulfone,
3,3'-Diallyl-4,4'-dihydroxy-diphenylsulfone, 3,3'-dichloro-4,4'-dihydroxydiphenylsulfone, 4-hydroxy-diphenylsulfone, 4-hydroxy-4'-isopropyldiphenylsulfone , 4-hydroxy-4'-isopropyloxydiphenylsulfone, 4-hydroxy-4'-benzyloxydiphenylsulfone, 2,4-dihydroxy-diphenylsulfone, 2,4-dihydroxy-4'
-methyldiphenylsulfone, 3,4-dihydroxyphenyl-p-trisulfone, and the like. Color developer is usually
1 to 5 parts by weight, preferably 1 part by weight per 1 part by weight of color-forming dye
．． They are mixed and used in a proportion of 5 to 3 parts by weight.

When the thermosensitive color forming layer is heated, the thermofusible material melts at a lower temperature than the color forming dye or color developer, forms a eutectic with the color forming dye and the color developer, and is capable of developing color at a low temperature. It is possible to mix a heat-sensitive color-forming layer coating with a thermofusible substance and a heat-fusible substance capable of improving the stability after color development.

Examples of thermofusible substances include stearic acid amide, stearic acid ethylene bisamide, oleic acid amide, palmitic acid amide, coconut fatty acid amide,
Fatty acid amides such as behenic acid amide, zinc stearate, calcium stearate, polyethylene wax,
Waxes (or lubricants) such as carnauba wax, paraffin wax, and ester wax, dimethyl terephthalate, dibutyl terephthalate, dibenzyl terephthalate, dibutyl isophthalate, phenyl 1-hydroxynaphthoate, 1,2
-di(3-methylphenoxy)ethane, 1,2-diphenoxyethane, 1-phenoxy-2-(4-methylphenoxy)ethane, diphenyl carbonate, p-benzylbiphenyl, 2,2'-methylenebis(4-methyl -6-t-
butylphenol), 4,4'-butylidene bis(6-
t-butyl-3-methylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 2,2'-methylenebis(4-ethyl-6-t- butylphenol), 2,4-di-t-butyl-3-methylphenol, 4,4'-thiobis(
Hindered phenols such as 3-methyl-6-t-butylphenol), sensitizers such as 2-(2'-hydroxy-5'-methylphenyl)-benzotriazole, and 2-hydroxy-4-benzyloxybenzophenone ,
Examples include antioxidants and ultraviolet absorbers. Generally, it is preferable that the thermofusible substance is contained in the thermosensitive coloring layer in a proportion of 4 parts by weight or less per 1 part by weight of the color developer.

In the present invention, all adhesives conventionally known as adhesives for heat-sensitive coloring layers can be used as the adhesive contained in the heat-sensitive coloring layer. However, it is preferable that the mixed liquid does not develop color, aggregate, or become highly viscous when mixed with the respective dispersions of the color-forming dye and color developer; The heat-sensitive recording layer film is required to be tough and to have no desensitizing effect.

Common water-soluble adhesives include polyvinyl alcohol, modified starch, gum arabic, gelatin, casein, chitosan, methylcellulose, hydroxyethylcellulose, hydroxymethylcellulose, polyvinylpyrrolidone, polyacrylate, polyacrylamide, and styrene-anhydrous. Maleic acid copolymer, methyl vinyl ether-maleic anhydride copolymer, isopropylene-maleic anhydride copolymer are used, and water-dispersible adhesives include styrene-butadiene latex, vinyl acetate-acrylic acid ester copolymer emulsion, and polyurethane. Emulsions, polyvinyl chloride emulsions, polyvinylidene chloride emulsions, methacrylic ester copolymer emulsions, acrylic ester copolymer emulsions, and the like can be used.

In order to strengthen the water resistance of the coating film, reactive groups such as acetoacetyl group, carboxyl group, etc.
Alternatively, it is preferable to use a water-soluble and/or water-dispersible polymeric substance containing an amide or the like in combination with a crosslinking agent.

Examples of crosslinking agents for water-soluble polymeric substances include dialdehyde compounds such as glyoxal and polyaldehyde, polyamine compounds such as polyethyleneimine, epoxy compounds, polyamide resins, diglycidyl compounds such as glycerin diglycidyl ether, Dimethylolurea compounds, aziridine compounds, blocked isocyanate compounds, and inorganic compounds such as ammonium persulfate, ferric chloride, magnesium chloride, and the like can be used.

The thermosensitive coloring layer may contain a pigment, particularly a white pigment, if necessary. Such pigments include
For example, calcium carbonate, magnesium carbonate, kaolin,
Clay, talc, calcined clay, silica, diatomaceous earth, synthetic aluminum silicate, zinc oxide, titanium oxide, aluminum hydroxide, barium sulfate, surface-treated inorganic fine powders such as calcium carbonate and silica, and urea-formalin. Examples include organic resin fine powder such as resin, styrene/methacrylic acid copolymer, and polystyrene resin.

[0024] If necessary, auxiliary additive components conventionally used in heat-sensitive recording materials, such as dispersants and surfactants, may be added to the heat-sensitive coloring layer. The coating amount of the heat-sensitive coloring layer is generally preferably 3 to 10 g/m2. As a coating method, methods conventionally used by those skilled in the art, such as a Meyer bar method, an air knife method, a blade method, a reverse roll method, and a slide die method, can be used. In addition, the surface of the heat-sensitive coloring layer is supercalendered.
Recording density and sensitivity can be improved by performing smoothing treatment using a gloss calender, machine calender, or the like.

[0025] As the support used in the present invention, wood-free paper, medium-quality paper, recycled paper, and coated paper can be used. In order to improve the oil resistance of heat-sensitive labels, the oil penetration rate of the support should be 10 mm/hour or less to prevent oil from entering from the cut end or back side of the support, thereby preventing oil from reaching the heat-sensitive coloring layer. This is even more effective.

[0026] To determine the oil penetration rate, a support cut into a rectangle of 15 mm x 100 mm was placed so that its long sides were perpendicular.
This can be determined by immersing one end of the lower part in commercially available salad oil and measuring the height of the translucent part from the oil liquid level after one hour. Oil penetration speed is 10mm/
When using a support of less than 1 hour, the printed heat-sensitive label was immersed in oil for 2 days, and even if the oil permeated the entire label, there was very little loss of the printed area.

In order to keep the oil penetration rate of the support to 10 mm/hour or less, in the case of high-quality paper, medium-quality paper, and recycled paper, it is necessary to increase the amount of internally added adhesive at the papermaking stage, or add an oil repellent to the pulp. This can be achieved by attaching it to the fibers to lower the surface tension of the pulp fibers, making them difficult to wet with oil.

[0028] Furthermore, it is also possible to increase the amount of adhesive in the size liquid in the size press step, or to add an oil repellent. Alternatively, paper that has already been made may be impregnated with an adhesive and/or an oil repellent. Furthermore, it is also possible to provide a coating layer with a high adhesive ratio on one or both sides of the paper. When a coating layer is provided, if the coating layer is on one side, it is desirable to have a structure in which a heat-sensitive coloring layer and an overcoat layer are provided thereon. As a coating method, an on-machine coater such as a bill blade method or a gate roll method, or an off-machine coater such as an air knife method, a blade method, a reverse roll method, a Meyer bar method, or a slit die method can be used.

The adhesive for internal addition can be appropriately selected from among the water-soluble adhesives exemplified as adhesives for the heat-sensitive coloring layer, but those with relatively low viscosity are preferred. Adhesive for internal addition is 0.5 to 5 for pulp fiber.
It is desirable to add it at a rate of %.

The oil repellent can be appropriately selected from those exemplified for dispersing color-forming dyes, color developers, and heat-fusible substances. The amount added is from 0.1 to the solid content of the paint.
10% is desirable. The paint used for size pressing, impregnation, and coating contains a water-soluble or water-dispersible adhesive, a pigment, and, if necessary, an oil repellent and a crosslinking agent.

Water-soluble and water-dispersible adhesives preferably have good film-forming properties, have a low film surface tension, and are insoluble in oil, but they can be appropriately selected from those exemplified for the heat-sensitive coloring layer. can do. Pigments, oil repellents, and crosslinking agents can also be appropriately selected from those exemplified for the heat-sensitive coloring layer. The adhesive/pigment ratio is high,
It is necessary to maintain good barrier properties. Adhesive/pigment=1
Coating amount is 1 to 10 g/m in the range of 00/0 to 50/50
It is desirable to set it within the range of 2.

[0032] The overcoat layer provided on the heat-sensitive coloring layer of the present invention is a coating material containing a water-soluble or water-dispersible adhesive, a crosslinking agent, a pigment and, if necessary, a lubricant, with a coating amount of 0 after drying. .5~5.0g/m2, preferably 1.0~
It can be obtained by coating to give a weight of 4.0 g/m2. If the coating amount is less than 0.5 g/m2, the coating film will not be formed uniformly, resulting in pinholes and coating defects.
Oil and plasticizer enter from there, causing a decrease in oil resistance and plasticizer resistance. If the coating amount exceeds 5.0 g/m2, there is a drawback that the sensitivity decreases and the print density becomes thin.

[0033] In addition, the resin/pigment ratio of the overcoat layer is preferably in the range of 80/20 to 40/60; if the resin compounding ratio exceeds 80%, sticking may occur during printing or printing may occur during label processing. There is a problem that the adhesion of the ink decreases. Furthermore, if the blending ratio of the resin is less than 40%, the barrier properties of the coating film will be low, and the oil resistance and plasticizer resistance will decrease. The adhesive, crosslinking agent, and pigment used in the overcoat layer can be those used in the heat-sensitive layer and the oil penetration prevention coating, and the same coating method can be used.

[0034] If necessary, a back layer may be provided on the opposite side of the heat-sensitive recording layer to the heat-sensitive coloring layer of the heat-sensitive recording material of the present invention to correct curls. The same paint and coating method as for the overcoat layer may be used for the back layer, and the coating amount and resin/pigment ratio may be changed as necessary.

[0035]

[Examples] The present invention will be explained in more detail with reference to Examples below, but the scope of the present invention is of course not limited to these. In each example, "parts" indicate "parts by weight."

Example 1 A dispersion liquid was prepared by using an oil repellent in addition to the dispersing adhesive during dispersion of the heat-sensitive color-forming dye and color developer to obtain a heat-sensitive color-forming paint. Solution A (thermosensitive dye dispersion) 3-(N-ethyl-N-isoamylamino)-
6-methyl-7-anilinofluorane

5 parts 10% methyl vinyl ether-maleic anhydride copolymer aqueous solution
5 parts Fluorine oil repellent (Asahi Guard AG-530 solid content 15%, Asahi Glass (
Co., Ltd.)
Part 3 Water

8 parts Liquid B (color developer dispersion) 2,4-dihydroxy-diphenylsulfone
30 copies
10% methyl vinyl ether-maleic anhydride copolymer aqueous solution 30 parts Fluorine oil repellent (Asahi Guard AG-530 solid content 15%,
Manufactured by Asahi Glass Co., Ltd.)

Part 18 Water

Part 21 Parts A and B were separately dispersed and pulverized using an Ultra Visco Mill, and the average particle size was adjusted to 1 μm or less. 35 parts of liquid A, 90 parts of liquid B, 45 parts of 60% calcium carbonate slurry,
40 parts of a 10% polyvinyl alcohol aqueous solution, 32 parts of SBR latex (OX-1060 solid content 50%, manufactured by Nippon Zeon Co., Ltd.), and 45 parts of water were mixed to prepare a heat-sensitive coloring layer coating.

Canadian Standard Freeness, 4
100 parts of bleached hardwood kraft pulp beaten to 50cc, 8 parts of talc, 1.5 parts of petroleum-based sizing agent, 1 part of sulfuric acid.
The above heat-sensitive coloring layer paint was coated on one side of paper with a basis weight of 64 g/m2 so that the coated amount after drying was 8 g/m2 to form a heat-sensitive coloring layer. .

The following overcoat layer paint was applied on the heat-sensitive coloring layer so that the coating weight after drying was 3.0 g/m2, and the following back layer paint was applied on the opposite side after drying. After coating so that the coating amount is 1.5g/m2,
After smoothing with a super calender, the Oken type smoothness (J. TAPPI No. 5) of the overcoat layer was 8.
A heat-sensitive recording medium for 50 seconds was obtained. Overcoat layer paint 60% kaolinite clay slurry
40 copies 1
0% modified polyvinyl alcohol aqueous solution
300 parts 10% casein solution
200 parts 30% zinc stearate dispersion
13 parts dimethylolurea crosslinking agent
Part 15 Water

300 parts were mixed to form an overcoat layer paint. Back layer paint 10% oxidized starch aqueous solution
300 parts 10% polyvinyl alcohol aqueous solution
100 copies water

1
00 parts were mixed to form an overcoat layer paint.

Example 2 An oil repellent was used when dispersing stearamide, which is a thermofusible substance, and the stearamide was dispersed with an Ultra Viscomil so that the average particle size was 1 μm or less, and the composition shown below was obtained. Solution C was prepared. Liquid C (thermofusible substance dispersion) Stearic acid amide
3
0 parts Dispersant (sodium polyacrylate, solid content 4
0%) 1.5 parts Fluorine oil repellent (Scotchban FC-829, solid content 3
0%, manufactured by Sumitomo 3M)
3 parts 10% methyl vinyl ether-maleic anhydride copolymer aqueous solution
30 parts water

2
5 parts 35 parts of liquid A used in Example 1, 90 parts of liquid B, and C
15 parts of liquid, 45 parts of 60% calcium carbonate slurry, 10
% polyvinyl alcohol aqueous solution, 32 parts of SBR latex (OX-1060, solid content 50%, manufactured by Nippon Zeon Co., Ltd.), and 43 parts of water were mixed to prepare a heat-sensitive coloring layer coating. This heat-sensitive color forming layer paint was applied to one side of the base paper made in Example 1 so that the coating amount after drying was 6 g/m2, and then an overcoat layer and a back layer were applied in the same manner as in Example 1. This was coated and smoothed using a super calender to obtain a heat-sensitive recording material whose overcoat layer had an Oken type smoothness of 700 seconds.

Example 3 A heat-sensitive recording material was obtained in the same manner as in Example 1, except that a paint having the following composition was prepared by adding an oil repellent to the heat-sensitive color forming layer paint of Example 1, and was applied. 35 parts of liquid A, 90 parts of liquid B, 6
45 parts of 0% calcium carbonate slurry, 40 parts of 10% polyvinyl alcohol aqueous solution, SBR latex (OX-1
060 Solid content 50%, manufactured by Nippon Zeon Co., Ltd.) 32 parts, fluorine oil repellent (Scotchiban FC-810, solid content 33%, manufactured by Sumitomo 3M) 2 parts, and water 45 parts

[0042]
Example 4, Example 5, Example 6 The base paper used in Example 1 was coated with starch/fluorine oil repellent (Scotchiban FC-810, solid content 33%, manufactured by Sumitomo 3M) = 95/
On one side of the support coated with the paint No. 5 so that the coating weight after drying was 1.5 g/m2, the same heat-sensitive coloring layer paint used in Example 1, Example 2, and Example 3 was applied. A heat-sensitive recording material was obtained. The oil penetration rate of the support is 6mm/
It was time.

Comparative Example 1 A thermosensitive coloring layer coating was prepared on one side of the base paper prepared in Example 1, except that a heat-sensitive coloring layer paint was prepared without using an oil repellent for dispersing the coloring dye and developer in Example 1. A thermosensitive recording material was obtained in the same manner as in Example 1.

After coating an acrylic adhesive on a release paper with a thickness of 65 μm so that the coated amount after drying was 25 g/m 2 , the thermal recording materials of Examples 1 to 6 and Comparative Example 1 were each coated. A heat-sensitive label was created by pasting it with the back side of the paper. Label printer (DP-110GS) after cutting to specified paper width
A barcode and characters were printed using a printer (manufactured by Teraoka Seiko Co., Ltd.), and the label was peeled off from the release paper and pasted onto PVC wrap. When a heat-sensitive label attached to PVC wrap is immersed in commercially available salad oil (edible blended oil, manufactured by Ajinomoto Co., Inc.),
Test samples in which the label surface was covered with PVC wrap and immersed in water were treated at 25° C. for 48 hours, and the print density of barcodes and characters was evaluated. The results are shown in Table 1, and the barcodes and letters of the samples of Examples remained and were sufficiently legible, but the samples of Comparative Examples immersed in salad oil lost both the barcodes and letters. , was illegible.

[Table 1] Print density: The density after printing was evaluated using a label printer DP-110GS (manufactured by Teraoka Seiko Co., Ltd.). ○: Good oil resistance: A heat-sensitive label attached to a PVC wrap film was immersed in salad oil (mixed salad oil, manufactured by Ajinomoto Co., Inc.), and the printed area was evaluated after 48 hours at 25°C. Resistant PVC wrap: The heat-sensitive label attached to the PVC wrap film was further covered with a PVC wrap film, and the printed area was evaluated after 48 hours at 25°C. Water resistance: A heat-sensitive label attached to a PVC wrap film was immersed in water, and the printed area was evaluated after 48 hours at 25°C. ◎: Almost no change ○: Characters are fully legible ×: Characters are not legible

[0044]

Effects of the Invention According to the present invention, it is possible to provide a heat-sensitive recording material that does not lose its color even if oil permeates through the cut cross section of the heat-sensitive recording material processed with a label.

Claims (3)

[Claims] Claim 1: A heat-sensitive coloring material containing, as main components, a colorless or light-colored electron-donating leuco dye on one side of a support, an organic acidic substance that causes the leuco dye to develop color when heated, a thermofusible substance, and an adhesive. In a heat-sensitive recording material, the heat-sensitive color-forming layer contains an oil repellent. A heat-sensitive recording medium characterized by the following. 2. The heat-sensitive recording material according to claim 1, wherein an oil repellent is contained when dispersing any one or more of a leuco dye, an organic acidic substance, and a thermofusible substance in the heat-sensitive coloring layer. A thermosensitive recording medium. 3. The heat-sensitive recording material according to claim 1, comprising:
A heat-sensitive recording material characterized in that the oil permeation rate of the support is 10 mm/hour or less.