JPH08197842A - Thermal recording material - Google Patents

Abstract

PURPOSE: To provide an excellent thermal recording material which is free from loss of recording information owing to coloring of a texture part, prevented from being altered, and free from loss of recording information owing to sticking by water. CONSTITUTION: An intermediate peeling layer is provided between a heat sensitive coloring layer consisting of at least a leuco base dye and a developer, and a support. For surface strength of a printed part by heating, the layer is not peeled off by tack grade ink 15 specified in JIS P8129 (method using IGT printability tester). For the surface strength of non-printing, the layer starts to be peeled off at 90m/s or over by tack grade ink 15 specified in JIS P8129 (method using IGT printability tester).

Description

Detailed Description of the Invention

The present invention relates to a heat-sensitive recording material, and more particularly to improvement of a heat-sensitive recording material utilizing a color-forming reaction between a leuco dye and a color developer.

[0002]

2. Description of the Related Art A heat-sensitive recording material comprises a support and a heat-sensitive coloring layer containing an electron-donating colorless or light-colored dye precursor and an electron-accepting developer as main components. By heating with a thermal head, a heating pen, a laser beam or the like, the dye precursor and the developer react instantaneously to obtain a recorded image. Since such a heat-sensitive recording material has the advantages that a recorded image can be obtained with a relatively simple device, maintenance is easy, and that noise is reduced, a facsimile, label,
In addition to the printer field, it is widely used as a recording material for ticket vending machines. On the other hand, these heat-sensitive recording materials have the property that the non-printed part (background part) develops color due to heat or chemicals even after information is recorded by printing, and they are tampered with by a hot pen or the like. In addition, there are inconveniences such that the non-printed portion is colored by mistake and the recorded information is damaged. To prevent these alterations, Japanese Patent Laid-Open No. 56-3
Japanese Patent No. 3990 discloses a method of dissolving the non-printed portion in water and leaving only the printed portion, but it is not practical because it takes time to process. On the other hand, since a water-soluble resin is used for the coating layer, if the coated surface dries while touching after being wet, if you try to forcibly remove the adhered material, the support will break, etc. There is a problem that the recorded information cannot be understood.

[0003]

DISCLOSURE OF THE INVENTION The object of the present invention is to improve the above-mentioned drawbacks of the prior art and to prevent the loss of recorded information due to the color development of the background portion, to prevent tampering, or to prevent the recorded information from sticking to water. It is an object of the present invention to provide an excellent heat-sensitive recording material without any loss.

[0004]

The object of the present invention is to provide an intermediate peeling layer between the thermosensitive color-developing layer comprising at least a leuco dye and a color developer and the support, and to prevent the printed portion from being heated. Tack grade ink 15 with surface strength of JIS P8129 (method using IGT printability tester)
No peeling of the layer, more preferably, no peeling of the layer with the tack grade ink 20 and a non-printing surface strength of JIS P
8129 (method using IGT printability tester),
Tack grade ink 15 is a thermosensitive recording material characterized in that delamination starts at 90 cm / s or more "," An intermediate release layer is provided between a thermosensitive coloring layer comprising at least a leuco dye and a developer and a support. The surface strength of the printed part due to heating is not peeled by the tack grade ink 15 of JIS P8129 (method using an IGT printing suitability tester), more preferably by the tack grade ink 20. , Non-printed surface strength is JIS P8129
A thermosensitive recording material (using an IGT printing aptitude tester) of tack grade ink 15 in which layer peeling starts at 90 cm / s or more, and the intermediate peeling layer is bonded to the resin of the thermosensitive coloring layer. Heat-sensitive recording material characterized by containing a thermoplastic material that has no property and is melted so that it is quickly bound to the heat-sensitive color developing layer by heating during recording "and" thermosensitive color developing layer comprising at least leuco dye and developer. An intermediate release layer is provided between the support and the support, and the surface strength of the printed portion due to heating is the tack grade ink 15 of JIS P8129 (method using an IGT printability tester), and the layer is not peeled off. Preferably, the tack-grade ink 20 does not cause delamination and has a non-printing surface strength of JIS P8129 (I
A method of using a GT printing aptitude tester), which is a thermosensitive recording material in which delamination starts at 90 cm / s or more with a tack grade ink 15 and has a binding property between the intermediate release layer and a resin of a thermosensitive coloring layer. And a thermosensitive recording material characterized by containing a thermoplastic material and a surfactant which are melted so as to be bound to the thermosensitive coloring layer promptly by heating during recording ". Between the heat-sensitive coloring layer and the support, the layer binding is strengthened by heating during printing, but in the case of non-printing, the layer binding is usually weak and layer collapse occurs due to external peeling operation. By providing the intermediate peeling layer, it is possible to peel off the non-printed portion after printing the recorded information, eliminate the coloring of the background portion, protect the recorded information, or prevent tampering. Further, even when a product wet with water is dried and stuck, the intermediate peeling layer of the non-printed portion is easily peeled off, so that the recorded information in the printed portion is not damaged. The layer binding force and / or the upper and lower interlayer binding force of the intermediate release layer in the present invention are the strength of the support which is the lower layer in the non-printed portion, the layer binding force of the upper thermosensitive coloring layer, and, if necessary, the upper thermosensitive coloring layer. Or, the protective layer provided below, a layer binding force of the intermediate layer, etc. and less than the interlayer binding force, and
By heating during printing, it exhibits the same binding strength as other layers. Also, the surface strength of the printed part due to heating is
P8129 (Method using IGT printability tester)
Of the tack grade ink 15 having a layer peeling has a problem that the peeling of the printed portion partially occurs at the peeling of the non-printed portion, and the surface strength of the non-printed portion is JIS P8129 (IG
The method using a T-printing aptitude tester), which has a tack-grade ink 15 and does not cause layer peeling at 90 cm / s or more, has a problem that the peeling work of the non-printed portion becomes difficult and the support is destroyed. Moreover, it was found that the layer peeling started at 90 cm / s or less had a problem that picking occurred during printing. Thus, the present inventors
Various investigations have been conducted as means for obtaining the intermediate release layer under the above-mentioned conditions, and the intermediate release layer of the present invention has been obtained. First, in order to obtain the predetermined strength between layers of the printed portion, a thermoplastic resin, preferably a thermoplastic material which is melted so as to quickly bond with the material of the adjacent layer by heating during recording, is added to the layer. , Can achieve its purpose. For example, styrene /
Emulsion latex such as butadiene emulsion resin, styrene / acrylic resin, acrylamide resin, polyvinyl alcohol, isobutylene / maleic anhydride resin, vinyl chloride / vinyl acetate copolymer, etc. may be used alone or in combination. Of course, these are illustrative rather than limiting of the invention.
In addition, it is necessary to give the non-printed portion the "peelability" aimed at in the present invention, and as a means for that, a filler and a resin in the layer, which suppress the binding force between other layers by adding a surfactant. The means for controlling the interlayer strength by controlling the ratio, controlling the interlayer strength by using an additive having a cohesive effect on the resin, and the like have been investigated. Surprisingly, by using a resin having no binding property between the resin used for the above and the resin used for the thermosensitive coloring layer applied on the upper layer, and further adding a surfactant in the intermediate release layer, It was found that the binding force between other layers in the non-printed portion can be adjusted without sacrificing the interlayer strength of the. Such a release layer can be applied not only between the support and the thermosensitive coloring layer, but also between the thermosensitive coloring layer and the upper protective layer, for example.

That is, the resin used in the intermediate release layer has no binding property with the resin of the thermosensitive coloring layer in the unheated region, but has the binding property with the resin of the thermosensitive coloring layer in the heating region. It is preferable to select such a material, but firstly, this is selected in consideration of the correlation between the resin component in the intermediate release layer and the type of the resin component in the thermosensitive coloring layer which is a binding partner. Secondly, in the field of thermal recording materials, a certain range of resins, generally a limited range of water-soluble resins or aqueous emulsions or latex resins,
Means that the resin used in the intermediate release layer of the present invention is limited to a certain range. Initially we expected this choice to be fairly wide.
Therefore, a fairly wide range of materials has been investigated. For example, a coating solution containing a water-soluble polymer material whose properties change after heating after heating, and a cross-linking agent for converting the water-soluble polymer material into a poorly water-soluble polymer compound, or However, the examination was made under the assumption that the coating liquid may further contain a third component which is ineffective or decomposes after heating the crosslinking agent. In this case, as the water-soluble polymer material, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, starches, gelatin, gum arabic, casein, styrene / maleic anhydride copolymer hydrolyzate, ethylene / Maleic anhydride copolymer hydrolyzate, isobutylene / maleic anhydride copolymer hydrolyzate, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, polyacramide, etc. have been investigated as candidates, and water-soluble polymer materials have been impaired. As a cross-linking agent for changing into a soluble polymer compound, a water-soluble initial condensation resin such as N-methylol urea, N-methylol melamine, urea-formalin, benzoguanamine-formalin, and acetoguanamine-formalin, a dialdehyde compound such as glyoxal, glutamine aldehyde, etc. , Boric acid, inorganic crosslinking agents such as borax, polyacrylic acid, methyl vinyl ether / maleic acid copolymer, although isobutylene / maleic anhydride copolymer, etc. have been studied, the results were not Kobashiku. Also, when the cross-linking agent was applied between the intermediate peeling layer and the thermosensitive coloring layer instead of being contained in the intermediate peeling layer, there was no difference in the results.

It has also been investigated to use pectins and a combination of cross-linking agents for converting the pectins into poorly water-soluble polymer compounds. Pectins are natural carbohydrates and polysaccharides that exist as constituents of plant cell tissues, and their main components consist of partially methylated polygalacturonic acid and the amide, sodium, potassium, or calcium salt of its carboxy group. It is a polysaccharide having a degree of 150 to 500 and is roughly classified into a high methoxy pectin and a low methoxy pectin depending on its degree of esterification, and any pectin was examined. Although pectins can be hardened and modified by alkaline earth metal ions such as calcium and magnesium, it is said that it is preferable to treat pectin with a modifying agent to crosslink it in order to sufficiently harden and modify it. As the agent for hardening and modifying, an aqueous solution containing calcium chloride, calcium acetate, calcium oxalate, calcium lactate, calcium citrate, calcium tartrate, magnesium chloride, magnesium acetate, magnesium oxalate, magnesium lactate, magnesium citrate, magnesium tartrate, or Furthermore, this aqueous solution can be an aqueous solution containing calcium ions and magnesium ions, while as a pectin cross-linking agent, formalin, glyoxal, glucine, glycidyl ester, glycidyl ether, dimethylol urea, ketene dimer, dialdehyde starch. , Melamine resin, polyamide resin, polyamide epoxy resin, ketone-aldehyde resin, polyethyleneimine resin, boric acid, borax, ammonium chloride, aluminum sulfate , Mention may be made of zirconium carbonate Ann fir um, titanium alkoxide, zirconium alkoxide, aluminum alkoxide and the like. However, the results of these examinations were not as good as expected. In addition, studies were also conducted on other materials that turn into macropolymers by heating. That is, a combination of a polycondensate which is prepolymerized / precondensed and has a carboxyl group at the terminal and glycidyl methacrylate which reacts with the carboxyl group at the time of heating printing, or a prepolycondensate having a hydroxyl group at the terminal reacts with the hydroxyl group when heated Then, a combination of toluidine diisocyanate which is isocyanated with 2-hydroxyethyl methacrylate which reacts with the isocyanate group (US Pat. No. 3,689,59
No. 3) or vinylphenyl ketene methyl trimethylsilyl acetal to obtain a prepolymerized macromonomer containing a styryl group by a group transfer polymerization method to form a macropolymer by heating and heat-polymerizing it. No. 62-62809) or a living polymer having a functional group capable of being polymerized at a terminal by a cationic polymerization method using a hydrogen iodide / iodine system as an initiator (Ebara et al, “Polymer
Preprint Japan ", 35 [2] p197 (1986)) or by synthesizing a living polymer by an anionic polymerization method, and a terminal anion and a halogen compound (having a polymerizable functional group such as methacryloyl chloride or chloromethylstyrene).
A polymer having a functional group which is polymerizable by the reaction of (A) is polymerized when heated (see Japanese Patent Laid-Open No. 116586/1975).
l Polymerized by immortal polymerization using porphyrin complex with a polymerizable functional group at the end (Kuroki, et al, “J. Am. Chem. Soc.”, [109] p4747
(1987)) was considered. The results were not good. In the present invention, through these studies, it was proved again that the change in properties after heating is such that the bondability between the resin of the thermosensitive coloring layer and the resin is increased. It can be enhanced by adding a thermoplastic resin, and the interlayer strength of the non-printed area can be increased by using a resin material that has no binding force with the resin of the thermosensitive coloring layer in the intermediate release layer and adding a surfactant. Was found to be adjustable.

As the surfactant used in the present invention, among the known nonionic, anionic, cationic or amphoteric surfactants, the surfactants which act on the resin used in the intermediate release layer are known. It is possible to appropriately select a substance that does not cause mild precipitation or aggregation. Nonionic and anionic surfactants are often preferred. Particularly preferred surfactants include polyalkylene glycol phenyl ether (eg, polyoxyethylene nonyl phenyl ether), sodium alkyl benzene sulfonate (eg, sodium dodecylbenzene sulfonate), dioctyl sodium sulfosuccinate, sodium lauryl alcohol sulfate ester, alginic acid. Examples thereof include sodium salts and fatty acid metal salts. Cationic resins such as polyethyleneimine resin, cationic polyamine resin, cationic polyamide / epoxy resin, cationic urea resin, and cationic polyamide / urea resin are often used in the field of this heat-sensitive recording material. It Among them, the polyethyleneimine resin and the cationic polyamine resin are sometimes preferably used because they are particularly excellent in the effect of improving the recording sensitivity and the image quality, but such a cationic resin also generally promotes the aggregation of the pigment and immobilizes the coating solution. It is also said that it has the effect of accelerating the conversion to high speed, and as a result, the coating solution has a high porosity and has a bulky structure, resulting in high recording sensitivity. However, on the other hand, if too much cationic resin is added, the fluidity of the coating liquid will deteriorate due to its cationic nature, making it difficult to coat, so be careful.
The surfactant to be employed in this case will also be different from that described above.

In the present invention, a low melting point material such as wax may be contained in the intermediate release layer within a range that does not impair the intended purpose. As the low melting point material, 40 to 1
Paraffin wax having a melting point of 00 ° C., microcrystalline wax, oxidized paraffin wax, oxidized microwax, candelilla wax, carnauba wax, beeswax, montana wax, ceresin wax, polyethylene wax, oxidized polyethylene wax, castor wax, beef tallow oil, Stearic acid, palmitic acid, lauric acid, lanolin, water wax, sorbitan stearate, sorbitan distearate, sorbitan palmylate, stearyl alcohol, polyamide wax, oleylamide, stearylamide, hydroxystearic acid, synthetic ester wax, synthetic In addition to wax-like substances such as metal-containing ester wax, polyoxyethylene oleyl ether, and polyoxyethylene nonylphenol ether, petroleum Fat, rosin, ester gum, ketone resins, epoxy resins, ethylene / vinyl acetate copolymer, and a low-melting thermoplastic resin such as ethylene / alpha-olefin copolymer.

The leuco dyes used in the present invention may be used alone or in admixture of two or more. As such leuco dyes, those applied to this type of heat-sensitive material are arbitrarily applied, for example, triphenylmethane-based, fluorane-based, phenothiazine-based, auramine-based, spiropyran-based, indolinoflalide-based, etc. Leuco compounds of dyes are preferably used. Specific examples of such leuco dyes include, for example, those shown below. 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-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3-N-methyl-N-isobutyl-6- Methyl-7
-Anilinofluorane, 3-N-ethyl-N-isoamyl-6-methyl-7-anilinofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino -7,8
-Benzfluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3- (N-ethyl-Np-
Tolyl) -6-methyl-7-anilinofluorane, 3-
(Np-tolyl-N-ethylamino) -6-methyl-
7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2 {N- (3'-trifluoromethylphenyl) amino} -6-diethylaminofluorane, 2- {3,6 -Bis (diethylamino) -9
-(O-chloranilino) xanthylbenzoic acid lactam}, 3-diethylamino-6-methyl-7- (m-trichloromethylanilino) fluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3-dibutylamino- 7- (o-chloroanilino) fluorane, 3-N-methyl-N-amylamino-6-methyl-
7-anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6- Methyl-7-
(2 ', 4'-Dimethylanilino) fluorane, 3-
(N, N-diethylamino) -5-methyl-7- (N,
N-dibenzylamino) fluorane, benzoyl leuco methylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrrilospirane, 6'-bromo-3'-
Methoxy-benzoindolino-pyrrilospirane, 3-
(2'-hydroxy-4'-dimethylaminophenyl)
-3- (2'-methoxy-5'-chlorophenyl) phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-nitrophenyl) phthalide, 3 -(2'-hydroxy-4'-diethylaminophenyl) -3- (2'-methoxy-3'-
Methylphenyl) phthalide, 3- (2'-methoxy-
4'-dimethylaminophenyl) -3- (2'-hydroxy-4'-chloro-5'-methylphenyl) phthalide, 3-morpholino-7- (N-propyl-trifluoromethylanilino) fluorane, 3- Pyrrolidino-7-
Trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7- (N-benzyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7-
(Di-p-chlorophenyl) methylaminofluorane,
3-diethylamino-5-chloro-7- (α-phenylethylamino) fluorane, 3- (N-ethyl-p-toluidino) -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- (N-methyl-N-isopropylamino) -6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-
7-anilinofluorane, 3,6-bis (dimethylamino) fluorene spiro (9,3 ')-6'-dimethylaminophthalide, 3- (N-benzyl-N-cyclohexylamino) -5,6- Benzo-7-α-naphthylamino-1′-bromofluorane, 3-diethylamino-6-
Chlor-7-anilinofluorane, 3-N-ethyl-N
-(2-Ethoxypropyl) amino-6-methyl-7-
Anilinofluorane, 3-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-mesitidino-4,5-benzofluorane, 3 -Diethylamino-
6-dimethylaminofluorene-9-spiro-3'-
(6'-Dimethylamino) phthalide, 3,6-bis (diethylamino) fluorene-9-spiro-3 '-(6'
-Dimethylamino) phthalide, 3-dibutylamino-6
-Dimethylaminofluorene-9-spiro-3'-
(6′-Dimethylamino) phthalide, 3-diethylamino-6-dimethylaminofluorene-9-spiro-3 ′
-(6'-diethylamino) phthalide, 3,3-bis {2- (p-dimethylaminophenyl) -2- (p-methoxyphenyl) ethenyl} -4,5,6,7-tetrachlorophthalide, 3- (4'-diethylamino-2 '
-Methoxyphenyl) -3- {4 "-(p-diethylaminophenyl) -4"-(p-chlorophenyl) -1 "
-3 ″ -butadienyl} -benzo {α} phthalide, etc. Further, as the color developing agent used in the thermosensitive coloring layer of the present invention, various electron-accepting compounds that cause the leuco dye to develop color upon contact, for example, phenolic compounds. , Thiophenolic compounds, thiourea derivatives, organic acids and metal salts thereof are preferably applied, and specific examples thereof include the following: 4,4′-isopropylidene bisphenol, 4,4 ′ -Isopropylidene bis (o-methylphenol), 4,4'-secondary butylidene bisphenol, 4,4'-isopropylidene bis (2-tert-butylphenol), 4,4'-cyclohexylidene diphenol, 4, 4'-isopropylidene bis (2-chlorophenol), 2,2'-methylene bis (4-methyl-6-tersia) Over-butylphenol),
2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 4,4'-butylidenebis (6
-Tert-butyl-2-methylphenol), 1,
1,3-Tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-Tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 4,1 ′ -Thiobis (6-tert-butyl-2-methylphenol), 4,4'-diphenol sulfone, 4-isopropoxy-4'-hydroxydiphenyl sulfone, 4-benzyloxy-4'-hydroxydiphenyl sulfone, 4,4 '-Diphenol sulfoxide, isopropyl p-hydroxybenzoate,
Benzyl p-hydroxybenzoate, benzyl protocatechuate, stearyl gallate, lauryl gallate, octyl gallate, 1,7-bis (4-hydroxyphenylthio) -3,5-dioxaheptane, 1,5-bis ( Four
-Hydroxyphenylthio) -3-oxapentane,
1,3-bis (4-hydroxyphenylthio) -propane, 1,3-bis (4-hydroxyphenylthio) -2
-Hydroxypropane, N, N'-diphenylthiourea, N, N'-di (m-chlorophenyl) thiourea, salicylanilide, 5-chloro-salicylanilide, 2-
Hydroxy-3-naphthoic acid, 2-hydroxy-1-naphthoic acid, 1-hydroxy-2-naphthoic acid, metal salts of hydroxynaphthoic acid such as zinc, aluminum and calcium, bis- (4-hydroxyphenyl) acetic acid methyl ester , Bis- (4-hydroxyphenyl) acetic acid benzyl ester, 1,3-bis (4-hydroxycumyl) benzene, 1,4-bis (4-hydroxycumyl) benzene, 2,4′-diphenolsulfone, 3,4-dihydroxy-4'-methyldiphenyl sulfone, 3,3'-
Diallyl-4,4'-diphenol sulfone, α, α-
Bis (4-hydroxyphenyl) -α-methyltoluene, zinc thiocyanate antipyrine complex, tetrabromobisphenol A, tetrabromobisphenol S
etc. When a leuco dye and a color developer are bound and supported on a support in order to produce the heat-sensitive recording material of the present invention, various conventional binders can be appropriately used, and specific examples thereof include the following. The following are listed. Polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylic acid ester copolymer, acrylamide / acrylic acid ester /
Methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, and other water-soluble polymers, as well as polyacetic acid Vinyl, polyurethane, polyacrylic ester,
Emulsion of polymethacrylic acid ester, vinyl chloride / vinyl acetate copolymer, ethylene / vinyl acetate copolymer and the like, latex of styrene / butadiene copolymer, styrene / butadiene / acrylic copolymer and the like. Further, in the thermosensitive coloring layer of the present invention, together with the leuco dye and the developer, if necessary, an auxiliary additive component commonly used in thermosensitive recording materials of this kind, for example, a filler, a dispersant, a color image stabilizing agent. , An antioxidant, a defoaming agent, a light stabilizer, a fluorescent whitening agent, a surfactant, a heat-fusible substance (or a lubricant) and the like can be used in combination. In this case, as the filler,
For example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate,
Examples include inorganic fine powders such as clay, talc, surface-treated calcium and silica, and organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer and polystyrene resin. As the heat fusible substance, for example, stearic acid, fatty acids such as behenic acid, stearic acid amide, fatty acid amides such as palmitic acid amide, zinc stearate, aluminum stearate, calcium stearate, zinc palmitate, Fatty acid metal salts such as zinc behenate, p-benzylbiphenyl, terphenyl, triphenylmethane, benzyl p-oxybenzoate, p-benzyloxynaphthalene, β-
Benzyloxynaphthalene, β-naphthoic acid phenyl ester, 1-hydroxy-2-naphthoic acid phenyl ester, 1-hydroxy-2-naphthoic acid methyl ester, diphenyl carbonate, terephthalic acid dibenzyl ester, terephthalic acid dimethyl ester, 1,4 -Dimethoxynaphthalene, 1,4-diethoxynaphthalene,
1,4-dibenzyloxynaphthalene, 1,2-bis (phenoxy) ethane, 1,2-bis (3-methylphenoxy) ethane, 1,2-bis (4-methylphenoxy) ethane, 1,4-bis (Phenoxy) butane, 1,
4-bis (phenoxy) -2-butene, dibenzoylmethane, 1,4-bis (phenylthio) butane, 1,4-
Bis (phenylthio) -2-butene, 1,3-bis (2
-Vinyloxyethoxy) benzene, 1,4-bis (2
-Vinyloxyethoxy) benzene, p- (2-vinyloxyethoxy) biphenyl, p-aryloxybiphenyl, p-propargyloxybiphenyl, dibenzoyloxymethane, 1,3-dibenzoyloxypropane, dibenzyl disulfide, 1 , 1-diphenylethanol, 1,1-diphenylpropanol, p- (benzyloxy) benzyl alcohol, 1,3-diphenoxy-2-propanol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene, N-octadecylcarbamoylbenzene and the like. Can be mentioned. Further, the heat-sensitive recording material of the present invention can be provided with a protective layer, if necessary. The resin used is PVA, modified PVA,
Methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, starches, gelatin, gum arabic, casein, polyvinyl alcohol, carboxyl modified polyvinyl alcohol, polyacrylamide,
Polyamide-polyacrylamide copolymer, styrene-
Examples thereof include maleic anhydride copolymers, isobutylene-maleic anhydride copolymers, diisobutylene-maleic anhydride copolymers and the like. Further, as the crosslinking agent, polyamide, epichlorohydrin resin, melamine formaldehyde resin,
Glyoxal, glycidyl amine-based cross-linking agents, aziridine-based cross-linking agents, zirconium compounds and the like can be mentioned, and they are preferably selected appropriately according to the type of polymer. Note that these are merely examples, and the present invention is not limited to these. Paper is mainly used as the support used in the heat-sensitive recording material of the present invention, but various non-woven fabrics, plastic films, synthetic papers, metal foils, etc., or composite sheets obtained by combining these may be arbitrarily used. .

[0010]

EXAMPLES Next, examples of the present invention will be described in more detail. The "parts" and "%" shown below are based on weight. Example 1 [Formation of intermediate release layer] 27% styrene acrylic emulsion 36 parts (hollowness 50%) 47.5% styrene-butadiene copolymer 10 parts Nonionic surfactant 0.1 part (SN Wet 366 San Nopco ( Water) 29 parts Stir the mixture having the above composition to prepare a coating solution for the intermediate release layer, and coat it on a high quality paper having a basis weight of 50 g / m ² using a wire bar so that the coating amount after drying will be 4 g / m ^2. It dried and formed the intermediate peeling layer. [Formation of thermosensitive coloring layer] <A liquid> 3-dibutylamino-6-methyl-7-anilinofluorane 10 parts 10% polyvinyl alcohol aqueous solution 10 parts water 20 parts <B liquid> 4-hydroxy-4′-iso Propoxydiphenyl sulfone 10 parts Oxalic acid paramethylbenzyl ester 20 parts Hydrous silicon dioxide 5 parts 10% Polyvinyl alcohol aqueous solution 25 parts Water 40 parts The mixture of the above composition was dispersed in a ball mill for 24 hours respectively, and then <A solution> and <B. Liquid> was adjusted. Then, <
Solution A> and <B solution> are mixed in a weight ratio of 1: 2 to obtain a thermosensitive color developing layer coating solution, and the coating amount after drying on the intermediate release layer is 8 g / m ^2. It was applied using a wire bar and dried to form a thermosensitive coloring layer. [Formation of protective layer] <Protective layer coating liquid> 20% silicon oxide dispersion liquid 2.5 parts 10% modified polyvinyl alcohol aqueous solution 10 parts (itaconic acid-modified PVA saponification degree 87 mol%) 30% zinc stearate dispersion liquid 0. 3 parts 12.5% polyamide epichlorohydrin aqueous solution 3.2 parts The above protective layer coating solution was applied to the surface of the above thermosensitive color developing layer coated paper using a wire bar so that the dry adhesion amount was 3.5 g / m ^2. After coating and drying, surface treatment was carried out with a super calender to prepare a heat-sensitive recording material of the present invention. Example 2 The heat-sensitive material of the present invention was prepared in the same manner as in Example 1 except that 36 parts of the 27% styrene acrylic emulsion in the coating liquid for the intermediate release layer of Example 1 was 70 parts and no nonionic surfactant was added. The recording material was created. Example 3 This example was prepared in the same manner as in Example 1 except that 1 part of a 12.5% polyamide epichlorohydrin aqueous solution was added to the coating liquid for the intermediate release layer of Example 1 and no nonionic surfactant was added. A heat-sensitive recording material of the invention was prepared. Comparative Example 1 A thermosensitive recording material of the present invention was prepared in the same manner as in Example 1 except that the nonionic surfactant in the coating liquid for the intermediate release layer of Example 1 was not added. Comparative Example 2 The thermosensitive recording material of the present invention was prepared in the same manner as in Example 1 except that the following coating liquid was used in place of the intermediate release layer coating liquid of Example 1 and the dry adhesion amount was 3.5 g / m ^2. Created. 47% styrene acrylic emulsion 3 parts (hollowness 0%) 20% silicon dioxide dispersion 5 parts 10% modified polyvinyl alcohol aqueous solution 5 parts (itaconic acid modified PVA saponification degree 87 mole%) 12.5% polyamide epiclohydrin aqueous solution 1 Part Water 1 part [Evaluation method] Image printing sample preparation Using a simulator printing device made by Okura Electric Co., head power 0.45 w / dot, scanning line density 8 × 7.7 dot /
A printed image was recorded with a pulse width of 1.0 mm and a pulse width of 1.0 msec. 1. Measurement of surface strength In accordance with JIS P8129 (method using IGT printing suitability tester), a printed sample and a non-printed sample were measured using Toyo Ink SMX Tack Grade 20. 2. Peelability After the cellophane tape was attached from the non-printed portion to the image printed portion of the above sample, the tape was pulled upward to confirm the peeling of the layer. 3, Water-resistant sticking property The above sample was immersed in water at 22 ° C for 30 seconds, taken out, folded so that the printing surfaces overlap, and naturally dried for 15 hours in an environment at 22 ° C and 65% HR, and the sticking surface was peeled off. It was confirmed. [Evaluation results]

[0011] Peelability: ○ Only the non-printed part was peeled off and the printed image clearly remained. × Does not peel off. Or the paper is torn. Water resistance sticking resistance: ○ Only the non-printed part is peeled off and the printed image is clearly left. Or the paper is torn.

[0012]

As described above, according to the present invention, by easily peeling off the non-printed portion and leaving only the printed image portion, fog coloration does not occur on the background portion, it is excellent in tampering prevention, or Thus, it is possible to provide an excellent heat-sensitive recording material that does not impair image information due to sticking with water resistance.

Claims (1)

[Claims] 1. An intermediate release layer is provided between a thermosensitive coloring layer comprising at least a leuco dye and a color developer and a support, and the surface strength of a printed portion due to heating is JIS P8129 (IG
Tack Grade Ink 15 (Toyo Ink Mfg. SMX Tack Grade 1)
In 5), the layer strength is not peeled off and the non-printed surface strength is JIS P
8129 (method using IGT printability tester),
A heat-sensitive recording material characterized by Tack Grade Ink 15 (Toyo Ink Mfg. SMX Tack Grade 15), in which layer separation starts at 90 cm / s or more.