JPH0475830B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a heat-sensitive recording material, and more specifically, the storage stability of a heat-sensitive recording material containing an electron-donating component and an electron-accepting component, particularly water resistance, chemical resistance, plasticizer resistance, This invention relates to a heat-sensitive recording material with improved oil resistance and durability. <Prior Art> Heat-sensitive recording materials that generally have a colorless or light-colored leuco dye, that is, an electron-donating component, and a color developer that causes the leuco dye to develop color when heated, that is, an electron-accepting component, as coloring components, have not been put to practical use in the past. Compared to other heat-sensitive recording materials, it produces very clear colored images, so it is widely used as recording paper for computer output, facsimiles, recorders, etc., as well as for tickets, cards, etc. However, recording sheets using this heat-sensitive recording material cannot be exposed to water or water for long periods of time.
When it comes into contact with plasticizers, oils, etc., it causes discoloration of the colored areas, and further, unnecessary coloring of the uncolored areas due to contact with organic solvents, and even damage, so improvements are needed. <Problems to be Solved by the Invention> In view of the above problems, the present invention aims to improve the storage stability of heat-sensitive recording materials that produce colored images by heating, particularly water resistance, chemical resistance, oil resistance, plasticizer resistance, and The purpose is to improve durability. <Means for solving the problems> The present invention comprises: (a) a support (b) a heat-sensitive coloring layer mainly composed of an electron-donating component and an electron-accepting component (c) an intermediate layer if necessary (d) a protective layer The object of the present invention is to provide a heat-sensitive recording material characterized in that these are layered in the above order, and at least one of the heat-sensitive coloring layer and the intermediate layer contains an aqueous polyester polyurethane resin. The support referred to in the present invention is a sheet of vinyl chloride resin, polyester resin, polypropylene resin, etc., synthetic paper, laminated paper of synthetic resin and paper, or composite resin sheet with high water resistance, chemical resistance, and durability. A wide range of substrates can be used, such as supports with 30% carbon, paper, and metal foils. Particularly preferred are vinyl chloride resins and polyester resin sheets that exhibit strong binding strength with the aqueous polyester polyurethane resin constituting the present invention. Furthermore, the binding force between the support surface and the thermosensitive coloring layer can be improved by matting the surface of these resin sheets or providing an anchor coat layer. The thermosensitive coloring layer formed on one surface of the support is constructed by dispersing an electron-donating component and an electron-accepting component described below in a binder. In other words, examples of typical electron-donating components are:
Crystal violet lactone, 3-indolino-3-p-dimethylaminophenyl-6-dimethylaminophthalide, 3-diethylamino-7-
Chlorofluorane, 3-diethylamino-5-methyl-7-t-butylfluorane, 3-diethylamino-6-methyl-7-anilinofluorane,
3-diethylamino-6-methyl-7-p-butylanilinofluorane, 3-diethylamino-7
-dibenzylaminofluorane, 3-cyclohexylamino-6-chlorofluorane, 3-diethylamino-6-methyl-7-xylidinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3- Pyrrolidino-7-cyclohexylaminofluorane, 3-piperidino-6-methyl-7-toluidinofluorane, 3-pyrrolidino-6-methyl-7-(p-toluidino)fluorane, 3-piperidino-6-methyl- Examples include, but are not limited to, 7-anilinofluoran and 3-diethylamino-7-(m-trifluoromethylanilino)fluoran. Examples of electron-accepting components include 4-phenylphenol, 4-t-butylphenol, 4-t-butylphenol, and 4-phenylphenol.
-Hydroxyacetophenone, α-naphthol,
β-naphthol, 2,2'-dihydroxydiphenyl, 2,2'-methylenebis(4-chlorophenol), 2,2'-methylenebis(4-methyl-6-
t-butylphenol), methyl-4-hydroxybenzoate, benzyl-4-hydroxybenzoate, 4,4'-isopropylidene bis(2-
methylphenol), 4,4'-ethylenebis(2
-methylphenol), 1,1'-bis(4-hydroxyphenyl)-cyclohexane, 4,4'-isopropylidene diphenyl, 4,4'-cyclohexylidene bis(2-isopropylphenol),
Novolac type phenolic resin, 3,5-di-α-
Methylbenzyl salicylic acid, 4-hydroxybenzoic acid ester, bis(4-hydroxyphenyl)
There are acetic acid esters, etc., but in the present invention, 4,4'-dihydroxyphenyl sulfone, 4-hydroxyphenyl-4'-alkyloxyphenyl sulfone derivatives, 1,1'-thiobis(4-hydroxy- Sulfur atom-containing phenol compounds such as (6t-butylphenyl) are preferably used because they provide higher storage stability. Various water-based resins can be used as the binder for dispersing the electron-donating component and the electron-accepting component.
In the present invention, it is particularly preferable to use water-based polyester polyurethane resins as described below. The aqueous polyester polyurethane resin of the present invention can be obtained by reacting a polyester polyol obtained by condensing a dicarboxylic acid component with a glycol component and a polyisocyanate compound. Examples of the dicarboxylic acid component include oxalic acid, malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, trimethyladipic acid, pimelic acid, 2,2-dimethylglutaric acid, azelaic acid, sebacic acid, and fumaric acid. acid, maleic acid, itaconic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,
3-Cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, phthalic acid, terephthalic acid, isophthalic acid, 2,5-norporanedicarboxylic acid, 1,4-naphthalic acid, diphenic acid, 4,4'-oxy Examples include benzoic acid, diglycolic acid, thiodipropion, and 2,5-naphthalene dicarboxylic acid. These may be acid anhydrides, esters, chlorides, etc., and include, for example, dimethyl 1,4-cyclohexanedicarboxylate, methyl 2,6-naphthalene dicarboxylate, dimethyl isophthalate, dimethyl terephthalate, and diphenyl terephthalate. . Examples of glycol components include ethylene glycol, propylene glycol, 1,3-propanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, and 2,2-dimethyl-
1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-
2-isobutyl-1,3-propanediol,
1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,6-
Hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,
2,4,4-tetramethyl-1,3-cyclobutanediol, 4,4'-thiodiphenol, 4,
4'-methylene diphenol, 4,4'-(norbornylidene) diphenol, 4,4'-dihydroxybiphenol, o-, m- and p-dihydroxybenzene, 4,4'-isopropylidene diphenol, 4,4 '-isopropylidene bis(2,6-cyclophenol), 2,5-naphthalenediol, p-xylene diol, and the like. Furthermore, the polyisocyanate compounds used in the present invention include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate,
m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, trimethylhexamethylene diisocyanate, 1,4-cyclohexocyanate silane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate,
3,3'-dimethoxy-4,4'-biphenylene diisocyanate, 3,3'-dichloro-4,4'-biphenylene diisocyanate, 1,5-naphthalene diisocyanate, 1,5-tetrahydronaphthalene diisocyanate, etc. Can be mentioned. There is no limit to the polyisocyanate content and carboxyl group content in the aqueous polyester polyurethane resin of the present invention, but if the polyisocyanate content is too high, the adhesion and adhesion to the support will be reduced, and if it is too low, the flexibility of the film will be reduced. Since the properties tend to decrease, the content of the polyurethane segment is preferably 40% by weight or less. In addition, if the carboxyl group content is high, adhesion to the support and paint properties will improve, but the water resistance of the film will decrease, and if the carboxyl group content is low, not only will it be difficult to make it water-based, but the resin stability will decrease. Therefore, the carboxyl group content is preferably about 0.7 to 5% by weight. The resin can be made water-based by introducing a sulfonic acid group, a carboxylic acid, or a carboxylic acid group, but in the heat-sensitive recording material of the present invention, carboxylic acid which has good coating properties and high reactivity with a curing agent is used. Preferably, a base is introduced. The method for introducing the carboxylic acid group includes 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,2-
Dimethylolvaleric acid and the like are copolymerized as a glycol component when synthesizing a polyester polyol to obtain a carboxylic acid group-containing polyester polyol, and then reacted with a polyisocyanate compound to obtain an aqueous carboxylic acid group-containing polyester polyurethane resin. An aqueous carboxylic acid group-containing polyester polyurethane can be obtained by neutralizing with an organic amine such as ammonia, trimethylamine, or triethylamine. Furthermore, in order to further improve the water resistance of this aqueous polyester polyurethane resin film, it can also be used in combination with an aziridine-based crosslinking agent or the like. The water-based polyester polyurethane resin film obtained in this way not only exhibits remarkable water resistance, but also has remarkable barrier properties against oils, plastics, chemicals, etc., and exhibits strong adhesion to synthetic resins, making it durable and durable. A thermosensitive recording material with high properties can be obtained. As the main component of the binder of the heat-sensitive color forming layer in the present invention, it is preferable to use the water-based polyester polyurethane resin as described above, but in that case, it is also possible to use it in combination with the water-based resin shown below. If the polyester polyurethane resin is not used, the present invention can be carried out using the following aqueous resin alone. For example, polyvinyl alcohol, starches, hydroxyethylcellulose, gum arabic, polyvinylpyrrolidone, alkali salts of acrylic acid (or methacrylic acid) ester copolymers, styrene/
Alkali salts of maleic anhydride copolymers, alkali salts of isobutylene/maleic anhydride copolymers, water-soluble polymer compounds such as acrylamide copolymers, styrene/butadiene copolymers, polyvinyl acetate, acrylic ester copolymers This includes polymer latexes such as polymer latexes, and water-based resins such as emulsions. Furthermore, the heat-sensitive coloring layer of the present invention may optionally contain inorganic and organic pigments such as aluminum hydroxide, heavy and light calcium carbonate, titanium oxide, zinc oxide, barium sulfate, silica gel, activated clay, talc, Clay, satin white, kaolinite, calcined kaolinite, diatomaceous earth, synthetic kaolinite, polyolefin particles, polystyrene particles, urea-formalin resin particles, etc., and sensitizers such as stearamide, palmitic acid amide, oleic acid. Amide, lauric acid amide, ethylene bis stearamide, methylene bis stearamide, methylol stearamide, paraffin wax, higher alcohol, higher resin acid, etc. may be added. A heat-sensitive color forming coating liquid mainly consisting of a binder resin as described above, an electron-donating component consisting of a leuco dye, and an electron-accepting component consisting of an acidic substance is applied to the surface of the support, and dried to form a leuco dye-based heat-sensitive color forming layer. will be established. If necessary, an intermediate layer is provided on the heat-sensitive coloring layer obtained as described above. In this case, the intermediate layer is for separating the protective layer made of a solvent-based paint and the heat-sensitive coloring layer, and the material used for the intermediate layer is generally known water-soluble resin. In view of solvent resistance and compatibility with the leuco dye-based heat-sensitive coloring layer, it is preferable to use the above-mentioned aqueous polyester polyurethane resin as the main component. The intermediate layer in the present invention may contain additives such as a resin curing agent and a coating property modifier, if necessary. The intermediate layer contains, for example, casein, in order to modify the paint properties, coating properties, and coating film of the intermediate layer.
Gelatin, polybutyl alcohol, modified polyvinyl alcohol, polyvinylpyrrolidone, starch, modified starch, isobutylene-maleic anhydride resin, diisobutylene-maleic anhydride resin, polyacrylamide, modified polyacrylamide, methyl vinyl ether, maleic acid copolymer Mixing, carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, and as a water-soluble emulsion, resins such as vinyl acetate, polystyrene, acrylic ester, vinyl chloride-vinyl acetate copolymer, etc. are mixed with the above-mentioned water-based polyester polyurethane resin. be able to. Furthermore, when the water-based polyester polyurethane resin is not used in the intermediate layer, the various water-soluble resins described above can be used alone. Further, the intermediate layer may contain a curing agent, a surfactant, or an antioxidant, an ultraviolet absorber, etc. in order to improve the light resistance of the heat-sensitive recording material, if necessary. Furthermore, the protective layer referred to in the present invention is provided on the heat-sensitive recording material to improve water resistance, chemical resistance, abrasion resistance, etc., and for matching with a recording thermal head, and is made of, for example, polyurethane resin, acrylic resin, epoxy resin, etc. Various solvent-type polymers such as , fluorine-based resins, etc. are applicable, but polyurethane resins are especially suitable for use in the present invention in terms of water resistance and abrasion resistance. The heat-sensitive recording material of the present invention having the above structure is
It can be used as a normal thermal recording paper for facsimile, or it can be punched out to a desired size and used as various personal cards such as identification cards, driver's licenses, business cards, membership cards, etc. Furthermore, by providing a magnetic recording layer on the back side (opposite side of the thermosensitive coloring layer) of the support constituting the thermosensitive recording material of the present invention, it can be used as a thermosensitive magnetic recording material.
Furthermore, if a spallator is attached to the back surface via a pressure-sensitive adhesive layer, it can be used as a heat-sensitive recording material for labels. Furthermore, when used for the personal card, predetermined display items, such as company name, notes, commercials, various marks, patterns, etc., may be printed on the back side in monochrome or color. This expands the use of the card as a fashionable card. For example, it can be applied to various cards for general consumers, such as commemorative cards for cashier facilities such as amusement parks, messages attached to gifts for Valentine's Day, birthdays, etc., and gift cards. In this case, printing may be done directly on the back of the support using normal printing means, but it is also possible to first provide a white or colored coating layer on the back of the support and then print the specified display items on top of that. It's okay. In addition, when the heat-sensitive recording material of the present invention is applied as a card having a magnetic recording layer, the magnetic recording layer is made of a ferromagnetic material such as γ-Fe ₂ O ₃ , barium ferrite, strontium ferrite, polyester resin, vinyl chloride resin. It is formed by uniformly dispersing a binder such as a polyurethane resin in a solvent such as toluene or methyl ethyl ketone, applying this to the back surface of a support, and drying it. In this case, in order to prevent the trouble that the information recorded on the magnetic recording layer is erased or attenuated due to contact with products using permanent magnets such as handbag clasps, toys, and magnetic necklaces, the present invention uses Ferromagnetic materials such as barium ferrite and strontium ferrite have a coercive force of 1500~
It is preferable to use a material with a high coercive force of 5000 oersted. Furthermore, for the purpose of preventing counterfeiting, a plurality of high magnetic permeability magnetic layers such as Sendust or Permalloy, and magnetic layers having a low coercive force of about 200 to 1000 oersteds such as iron oxide magnetic powder can be laminated. Furthermore, when the heat-sensitive recording material of the present invention is used as a label with a separator provided through a heat-sensitive adhesive layer, any material used for conventional release labels can be used for the separator and the pressure-sensitive adhesive layer. For example, as a separator, a release paper obtained by providing a release layer such as a silicone resin on paper, and as a pressure-sensitive adhesive layer, SBR latex, natural rubber latex, rubber emulsion, acrylic emulsion, etc. are applicable to the present invention. <Examples> The present invention will be described in detail below using Examples and Comparative Examples. Note that parts in the recipe table represent parts by weight. A polyester polyurethane resin to be incorporated into the heat-sensitive coloring layer and/or intermediate layer constituting the heat-sensitive recording material of the present invention was synthesized as follows. 500 with stirrer, temperature system, nitrogen blowing device, and packed tower
83.3 parts of terephthalic acid, isophthalic acid in cc flask
After adding 46.5 parts of ethylene glycol, 45.6 parts of ethylene glycol, 21.2 parts of diethylene glycol, 0.2 parts of zinc acetate, and 0.4 parts of antimony trioxide and carrying out an esterification reaction at 190 to 220°C for 4 hours, a condensation reaction was carried out at 230 to 250°C under 1 mmHg. Ivy. Furthermore, 44.4 parts of sebacic acid, 2,
Add 26.8 parts of 2'-dimethylolpropionic acid
A carboxyl group-containing polyester polyol was obtained by reacting at 160 to 190°C for 20 hours. After dehydrating 100 parts of this polyester polyol,
Add 130 parts of methyl ethyl ketone and dissolve. Add 15 parts of hexamethyl diisocyanate and heat to 60-80℃.
After reacting for 12 hours at
% carboxylic acid group-containing polyester polyurethane resin aqueous solution was obtained. Furthermore, each of the mixtures having the following formulations was ground and dispersed in a ball mill for one day to prepare solutions A to C. A Liquid 3-N-methylcyclohexylamino-6-methyl-7-anilinofluorane (electron-donating component) 25 parts 5% hydroxyethyl cellulose aqueous solution 50 parts Water 25 parts B Liquid Bis(4-hydroxyphenyl)methyl acetate Ester (electron-accepting component) 15 parts 5% hydroxyethyl cellulose aqueous solution 60 parts Stearamide 15 parts Water 10 parts C Liquid light calcium carbonate 40 parts 10% polyvinyl alcohol aqueous solution 40 parts Water 20 parts Example 1 Above A liquid 10 parts , 33.3 parts of B liquid, 49 parts of C liquid, above
15 parts of 25% polyester polyurethane aqueous solution, 46 parts of water
A heat-sensitive recording layer coating material was obtained by mixing the two parts. The paint was applied to a matted polyester resin sheet with a thickness of 188 μm so that the coating amount after drying was 6 g/m ² , and after drying, 2 μm of ultraviolet curable ink having the composition shown in Liquid D below was applied. After coating to a film thickness,
Using an ultraviolet irradiation device (one 1.2 kw mercury lamp), ultraviolet rays were irradiated at a distance of 10 cm from the lamp and at a conveyance speed of 15 m/min to obtain a heat-sensitive recording material of the present invention having an ultraviolet curing protective layer. D Liquid polyester acrylate (Aronix
M8060, manufactured by Toagosei Kagaku Co., Ltd.) 100 parts Photoinitiator (Dalkyure 953, manufactured by MERCK)
5 parts polyethylene wax 5 parts Example 2 On the heat-sensitive coloring layer prepared in Example 1, a coating liquid E for an intermediate layer having the following formulation was prepared, applied and dried to form an intermediate layer. E Liquid 25% polyester polyurethane resin aqueous solution
45 parts hydroxypropyl cellulose aqueous solution (1%)
12 parts Sodium alkylbenzenesulfonate (1%)
1.5 parts Furthermore, a protective coating liquid F having the following formulation was prepared, and was applied and dried on the above intermediate layer to form a protective layer, thereby producing a heat-sensitive recording material of the present invention. F Liquid polyurethane resin (Hyprene PS-603, manufactured by Mitsui Nisso Urethane Co., Ltd., 30% solids) 16 parts Acrylic acid/methyl methacrylate copolymer (10
% solids) 20 parts fluorocarbon resin (Mold Bittu F-57,
(manufactured by Axel Plastics Research Co., Ltd., 8% solids) 20 parts toluene 30 parts Example 3 The electron accepting component bis(4-hydroxyphenyl) acetic acid methyl ester in Solution B in Example 1 was replaced with a sulfur atom-containing phenol. A heat-sensitive coloring layer was formed in the same manner as in Example 1, except that the compound 4-hydroxyphenyl-4'-propoxyphenyl sulfone was used, and then an intermediate layer and a protective layer were formed in the same manner as in Example 2. A heat-sensitive recording material of the present invention was obtained by forming the following. Comparative Example 1 The aqueous polyester polyurethane resin aqueous solution (25%) blended in the thermosensitive coloring layer and intermediate layer of Example 3 was mixed with a sodium sulfonate group-containing polyester resin aqueous solution (25%) (Eastman WD,
A heat-sensitive recording material was obtained in the same manner as in Example 3, except that the material was changed to (manufactured by Eastman Kodak Co.). The sheet-like heat-sensitive recording materials obtained in the above Examples and Comparative Examples were immersed in water in a water tank, and the period until changes such as formation of blisters or peeling of the protective layer occurred on the surface of the sheet was observed, and the water resistance was evaluated. did. In addition, as a chemical resistance test, methanol was dropped onto the surface of the sheet.
The time required for methanol to penetrate into the heat-sensitive layer and cause color development was investigated. The results are shown in Table 1.

[Table] As is clear from Table 1, it was confirmed that the heat-sensitive recording material of the present invention has superior water resistance and chemical resistance compared to the comparative example made by the prior art. Furthermore, a line head type thin film thermal head was used for the thermal recording layer of the thermal recording material of the present invention, and
When an image was recorded with an energy of (1 mJ/dot) and the solid black portion was measured with a Macbeth densitometer, a clear colored image of 1.21 was obtained. <Effects of the Invention> Since the heat-sensitive recording material of the present invention has the above structure, it has extremely excellent water resistance and chemical resistance. In addition, the heat-sensitive recording material of the present invention has excellent durability with no practical problems even when applied to applications such as cards and labels that require harsh handling and quality compared to ordinary facsimile applications. It was confirmed that

Claims (1)

[Scope of Claims] 1 (a) a support (b) a thermosensitive coloring layer mainly composed of an electron-donating component and an electron-accepting component (c) an intermediate layer if necessary (d) a protective layer, which are laminated in the above order, A heat-sensitive recording material characterized in that at least one of the heat-sensitive color forming layer and the intermediate layer contains an aqueous polyester polyurethane resin. 2. The heat-sensitive recording material according to item 1, wherein the electron-accepting component is a sulfur atom-containing phenolic compound. 3. The heat-sensitive recording material according to item 1, wherein the aqueous polyester polyurethane resin is an aqueous carboxylic acid group-containing polyester polyurethane resin.