JPH07223370A - Transparent thermal recording medium - Google Patents

Abstract

PURPOSE:To facilitate the production of a transparent thermal recording medium and improve the transparency by successively laminating a thermal recording layer and a protective layer on a transparent support and making the refractive indexes of both layers to be the same. CONSTITUTION:A transparent thermal recording medium is formed by providing thermal recording layers 2, 3 each based on an electron donating color forming compd., an electron acceptive compd. and a binder resin on a transparent support 1 and laminating protective layers 4, 5 thereon. In this case, the refractive indexes of the thermal recording layers and the protective layers must be made same and, especially pref., the refractive index of the transparent support is made almost same to that of the thermal recording layers and the protective layers. A positive image manuscript 13 wherein a carbon black containing image 6 is formed on a support 7 is superposed on the thermal recording layer 2 on the single surface of the obtained transparent thermal recording medium to be irradiated with flash light on the side of the recording medium by a lamp 8 to generate heat in the carbon black part of the image of the manuscript 13 and the thermal recording layer 2 is partially thermally etched to form a developed color image (a) 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording medium utilizing a color-developing reaction between an electron-donating color-forming compound and an electron-accepting compound, and particularly to an image for an overhead projector (hereinafter abbreviated as OHP). The present invention relates to a transparent thermosensitive recording medium useful as a forming film sheet and a CAD image forming film sheet.

[0002]

2. Description of the Related Art Conventionally, electron-donating color-forming compounds (hereinafter referred to as
A heat-sensitive recording medium utilizing a color-forming reaction between a color former and an electron-accepting compound (hereinafter also referred to as a developer) is widely known. In recent years, the usage has expanded, and it has been used for overhead projectors or diazo 2nd original drawings.
Furthermore, there are requirements for design drawings.

As a transparent thermosensitive recording medium which can be directly recorded by a thermal head, Japanese Patent Application No. 61-2187 is available.
No. 5 and JP-A-1-99873. However, in order to produce these transparent heat-sensitive recording media, a color-forming agent is microencapsulated, and a coating consisting of an emulsified dispersion obtained by emulsifying and dispersing a color-developing agent dissolved in a water-insoluble or insoluble organic solvent. There is a problem in production such as requiring a fairly complicated process such as coating a liquid on a transparent support to prepare the liquid, and there is also a problem that transparency is insufficient.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems found in the prior art in a heat-sensitive recording medium utilizing the reaction between a color former and a developer, and facilitates its production. It is an object of the present invention to provide a transparent thermosensitive recording medium that can be processed and has excellent transparency.

[0005]

According to the present invention, a thermosensitive recording layer containing an electron-donating color-forming compound, an electron-accepting compound and a binder resin as a main component is provided on a transparent support,
Further provided is a transparent thermosensitive recording medium having a protective layer formed on the thermosensitive recording layer, wherein the thermosensitive recording layer and the protective layer have the same refractive index. The transparent support has a refractive index substantially the same as that of the heat-sensitive recording layer and the protective layer, the transparent recording medium, the refractive index of the binder resin at room temperature, and the resin forming the protective layer. Has a refractive index of 1.45 at room temperature.
The transparent heat-sensitive recording medium characterized in that it is 1.60, the electron-accepting compound is an organic phosphorus compound, the transparent heat-sensitive recording medium characterized in that the organic phosphorus compound is the following general formula (I ) (Chemical formula 1) or general formula (II)
The transparent heat-sensitive recording medium, which is a phosphonic acid represented by the chemical formula 2.

[Chemical 1]  (In the formula, R represents a linear alkyl group having 16 to 24 carbon atoms.
Forget )

[Chemical 2] (In the formula, R'represents a linear alkyl group having 13 to 23 carbon atoms.) The electron-accepting compound has an average particle size of 10 μm or less, the transparent heat-sensitive recording medium, and the binder. The resin, the transparent heat-sensitive recording medium, which is a resin having a hydroxyl group in the molecule, in the heat-sensitive recording layer or in the protective layer, an ultraviolet absorber, an antioxidant, an antioxidant, singlet oxygen And one or more light stabilizers selected from quenchers of superoxide anion, and the transparent heat-sensitive recording medium, wherein the protective layer contains ultraviolet rays or electron beams. The transparent heat-sensitive recording mediums are provided, each of which is made of a curable resin and has a slip additive contained in the protective layer. Further, there is provided the transparent heat-sensitive recording medium characterized in that a heat-sensitive recording layer and a protective layer are sequentially provided on both sides of the transparent support, and further, the heat-sensitive recording provided on both sides of the transparent support. The transparent heat-sensitive recording medium is characterized in that the layers are heat-sensitive recording layers that develop different colors.

That is, the inventors of the present invention have conducted extensive studies to solve the above-mentioned problems, and as a result, a heat-sensitive recording layer comprising an electron-donating color-forming compound, an electron-accepting compound and a binder resin on a transparent support. In a transparent thermosensitive recording medium further provided with a protective layer thereon, the refractive index of each layer, or each layer and the support, preferably 1.45 to 1.6 at room temperature.
By setting 0, it is possible to achieve the above-mentioned object, and further, by containing one or more kinds of various light stabilizers in the heat-sensitive recording layer and / or the protective layer, It was found that the light resistance was remarkably improved, and the inclusion of a lubricating additive in the protective layer did not cause problems such as sticking caused by contact with the thermal head, and it was a transparent heat-sensitive material with excellent head matching properties. It was found that a recording medium could be obtained, and the present invention was completed.

Next, the transparent thermosensitive recording medium of the present invention will be described in detail. The color former used in the present invention is a colorless or light-colored dye precursor per se, and is not particularly limited, and conventionally known ones, for example, triphenylmethanephthalide compounds, fluorane compounds, phenothiazine compounds, leuco. Examples thereof include an auramine-based compound, a rhodamine lactam-based compound, a spiropyran-based compound, and an indinophthalide-based compound.

A particularly preferred color former used in the present invention is a fluoran compound, and specific examples thereof include the following. 3,6-dimethoxyfluorane 3-cyclohexylamino-6-chlorofluorane 3-dimethylamino-5,7-dimethylfluorane 3-diethylamino-5,7-dimethylfluorane 3-dimethylamino-7-chlorofluorane 3-Diethylamino-7-chlorofluorane 3-Dimethylamino-7-methylfluorane 3-Diethylamino-7-methylfluorane 3-Diethylamino-6-methyl-7-chlorofluorane 3-Diethylamino-6-methyl-7 -Bromfluorane 3-di-n-butylamino-6-methyl-7-bromofluorane 3-diethylamino-6-methyl-8-methylfluorane 3-di-n-butylamino-6-methyl-8- Methylfluorane 3-diethylamino-7,8-benzofluorane 3-di-n-bu Arylamino-7,8 benzofluoranthene 3- (N-n-butyl -N- methylamino) -7,8
Benzofluorane 3- (N-n-butyl-N-ethylamino) -7,8-
Benzofluorane 3- (N-iso-butyl-N-ethylamino) -7,
8-benzofluorane 3-di-iso-butylamino-7,8-benzofluorane 3- (N-iso-amyl-N-ethylamino) -7,
8-Benzofluorane 3,6-bis (diphenylamino) fluorane 3,6-bis (N-biphenyl-N-phenylamino)
Fluorane 3-diethylamino-7-anilinofluorane 3-di-n-butylamino-7-anilinofluorane 3- (Nn-hexyl-N-ethylamino) -7-anilinofluorane 3-diethylamino -7-Dibenzylaminofluorane 3-diethylamino-5-methyl-7-dibenzylaminofluorane 3-diethylamino-7-piperidinofluorane 3-diethylamino-7- (O-chloroanilino) fluorane 3-di- n-Butylamino-7- (O-chloroanilino) fluorane 3-dimethylamino-6-methyl-7-anilinofluorane 3-diethylamino-6-methyl-7-anilinofluorane 3-di-n-butylamino -6-Methyl-7-anilinofluorane 3- (Nn-propyl-N-methylamino) -6-me 7- anilinofluoran 3- (N-iso- propyl -N- methylamino) -6
-Methyl-7-anilinofluorane 3- (Nn-butyl-N-ethylamino) -6-methyl-7-anilinofluorane 3- (N-iso-butyl-N-methylamino) -6 −
Methyl-7-anilinofluorane 3- (Nn-amyl-N-methylamino) -6-methyl-7-anilinofluorane 3- (N-iso-amyl-N-ethylamino) -6-
Methyl-7-anilinofluorane 3- (N-cyclohexyl-N-methyl) -6-methyl-7-anilinofluorane 3- (Nn-amyl-N-ethylamino) -6-methyl-7 -Anilinofluorane 3- (N-P-tolyl-N-ethylamino) -6-methyl-7-anilinofluorane 3- (N-2-ethoxypropyl-N-ethylamino)
-6-Methyl-7-anilinofluorane 3-pyrrolidino-6-methyl-7-anilinofluorane 3- (N-tetrahydrofurfuryl-N-ethylamino) -6-methyl-7-anilinofluorane 3-Diethylamino-7- (m-trifluoromethylanilino) fluorane 3-diethylamino-6-methyl-7- (2 ', 4'-
Dimethylanilino) fluorane 3-diethylamino-6-chloro-7-anilinofluorane 3-diethylamino-5-methyl-7- (α-phenylethylamino) fluorane 3- (NP-tolyl-N-ethylamino) ) -7- (α
-Phenylethylamino) fluorane and the like.

In the present invention, as the color developing agent for developing the color developing agent, a phenolic compound and an organic phosphoric acid compound which are insoluble or sparingly soluble in a general solvent are preferable, and specific examples of the phenolic compound include Include gallic acid compounds, protocatechuic acid compounds, bis (hydroxyphenyl) acetic acid and the like, and specific examples of the organic phosphoric acid compounds include alkylphosphonic acid compounds, α-hydroxyalkylphosphonic acid and the like. Among them, organic phosphoric acid compounds are excellent in the background fog and thermal sensitivity.

Particularly preferred organic phosphoric acid compounds are the following general formula (I) (formula 1) or general formula (II)
The phosphonic acid represented by (Chemical Formula 2) is used.

[Chemical 1] (In the formula, R represents a linear alkyl group having 16 to 24 carbon atoms.
Forget )

[Chemical 2] (In the formula, R'represents a linear alkyl group having 13 to 23 carbon atoms.)

The following compounds may be mentioned as specific examples of the phosphonic acid represented by the general formula (I). There are hexadecylphosphonic acid, octadecylphosphonic acid, eicosylphosphonic acid, docosylphosphonic acid, tetracosylphosphonic acid and the like. Specific examples of the phosphonic acid represented by the general formula (II) include the following compounds. α-hydroxytetradecylphosphonic acid, α-hydroxylhexadecylphosphonic acid, α-hydroxyoctadecylphosphonic acid, α-hydroxyeicosylphosphonic acid, α-
Hydroxytetracosylphosphonic acid and the like. In the present invention, the color developers are used alone or in combination of two or more. Similarly, the color-developing agent can be applied alone or in a mixture of two or more kinds.

The average particle size of the color developer used in the present invention is preferably not more than 10 μm, more preferably not containing particles having a particle size of not more than 1 μm and more than 1 μm, and the heat sensitivity of the thermosensitive recording medium. And the resolution can be improved.

The binder resin used in the heat-sensitive recording layer preferably has a refractive index in the range of 1.45 to 1.60 at room temperature, such as phenol resin (1.50 to 1.60).
Urea resin (1.54 to 1.56), epoxy resin (1.55 to 1.61), polyester resin (1.52
~ 1.57), polyvinyl chloride resin (1.52-1.5
5), polystyrene (1.59 to 1.60), styrene-acrylonitrile copolymer (1.56 to 1.57),
Acrylic resin (1.45 to 1.60), polycarbonate (1.58 to 1.59), polyacetal (1.48)
~ 1.50), polyamide (1.52 to 1.53), polyurethane (1.50 to 1.60), alkyl cellulose (1.46 to 1.55), cellulose acetate (1.46 to 1.50). ), Cellulose acetate butyrate (1.46 to 1.49), cellulose acetate propionate (1.46 to 1.50), nitrocellulose (1.49 to 1.51) and the like. More preferably, it contains a hydroxyl group in the molecule, for example, polyvinyl butyral (1.48 to 1.49), polyvinyl acetal (1.50), epoxy resin (1.55 to 1.55).
1.61), ethyl cellulose (1.46 to 1.4)
9), cellulose acetate (1.46-1.50),
Cellulose acetate butyrate (1.46-1.4
9), cellulose acetate probionate (1.46
~ 1.49), nitrocellulose (1.49-1.5)
1) etc. are mentioned.

Further, the improvement of the light resistance of the thermosensitive recording medium of the present invention is achieved by incorporating a light stabilizer in the thermosensitive recording layer. As the light stabilizer used in the present invention,
Ultraviolet absorbers, antioxidants, antioxidants, singlet oxygen quenchers, and superoxide anion quenchers are used.

Examples of the ultraviolet absorber include 2,4-
Dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 2,2'-dihydroxy-4-
Methoxybenzophenone, 2,2'-dihydroxy-
4,4'-dimethoxybenzophenone, 2,2 ', 1,
4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone,
2-hydroxy-4-oxybenzylbenzophenone,
2-hydroxy-4-chlorobenzophenone, 2-hydroxy-5-chlorobenzophenone, 2-hydroxy-
4-methoxy-4'-methylbenzophenone, 2-hydroxy-4-n-heptoxybenzophenone, 2-hydroxy-3,6-dichloro-4-methoxybenzophenone, 2-hydroxy-3,6-dichloro-4-ethoxy Benzophenone-based UV absorbers such as benzophenone and 2-hydroxy-4- (2-hydroxy-3-methylacryloxy) propoxybenzophenone, 2- (2 '
-Hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-ditertiary-butylphenyl) benzotriazole, 2-
(2'-hydroxy-3'-tert-butyl-5 '
-Methylphenyl) benzotriazole, 2- (2'-
Hydroxy-4′-octoxy) benzotriazole,
2- (2'-hydroxy-3 ', 5'-ditertiary-
Butylphenyl) 5-chlorobenzotriazole, 2-
(3'-tert-butyl-2'-hydroxy-5 '
-Methylphenyl) 5-chlorobenzotriazole, 2
Benzotriazole-based UV absorbers such as-(2'-hydroxy-5-ethoxyphenyl) benzotriazole, phenyl salicylate, P-octylphenyl salicylate, P-tert-butylphenyl salicylate, carboxylphenyl salicylate, methylphenyl salicylate, dodecylphenyl Salicylate and other salicylate phenyl ester UV absorbers, or P-methoxybenzylidene malonic acid dimethyl ester,
2-ethylhexyl-2-cyano-3,3'-diphenyl acrylate, ethyl-2-cyano-3,3'-diphenyl acrylate, 3,5-ditertiary-butyl-
P-hydroxybenzoic acid, resorcinol monobenzoate rearranged by ultraviolet light to give benzophenone, 2,4
-Ditertiary-butylphenyl, 3,5-ditertiary-butyl-4-hydroxybenzoate and the like.

Examples of antioxidants and antiaging agents include:
2,6-ditertiary-butyl-4-methylphenol, 2,4,6-tritert-butylphenol,
Styrenated phenol, 2,2'-methylenebis (4-
Methyl-6-tert-butylphenol), 4,
4'-isopropylidene bisphenol, 2,6-bis (2'-hydroxy-3'-tert-butyl-5 '
-Methylbenzyl) -4-methylphenol, 4,4 '
-Thiobis- (3-methyl-6-tert-butylphenol), tetrakis- {methylene (3,5-ditertiary-butyl-4-hydroxyhydrocinnamate)} methane, para-hydroxyphenyl-3-naphthylamine, 2,2,2. 4-trimethyl-1,2-dihydroquinoline, thiobis (β-naphthol), mercaptobenzothiazole, mercaptobenzimidazole, aldol-2-naphthylamine, bis (2,2,6,6-tetramethyl-4-piperidyl) sepacate , 2, 2,
6,6-tetramethyl-4-piperidyl benzoate,
Examples include dilauryl-3,3 'thiodipropionate, distearyl-3,3'-thiodipropionate, tris (4-nonylphenol) phosphite and the like.

Carotene as a quencher for singlet oxygen,
There are dyes, amines, phenols, nickel complexes, sulfides, and the like. Examples thereof include 1,4-diazabicyclo (2,2,2) octane, β-carotene, 1,3-cyclohexadiene, and 2-diethylamino. Methylfuran,
2-Phenylaminomethylfuran, 9-diethylaminomethylanthoceracene, 5-diethylaminomethyl-6
-Phenyl-3,4-dihydroxypyran, nickel dimethyldithiocarbamate, nickel dibutyldithiocarbamate, nickel 3,5-di-t-butyl-4-hydroxybenzyl-O-ethylphosphonate, nickel 3,5-di-t -Butyl-4-hydroxybenzyl-O
-Butylphosphonate, nickel {2,2'-thiobis (4-t-octylphenolate)} (n-butylamine), nickel {2,2'-thiobis (4-t-octylphenolate)} (2- Ethylhexylamine), nickel bis {2,2'-thiobis (4-t-octylphenolate)}, nickel bis {2,2'-sulfonebis (4-octylphenolate)}, nickel bis (2
-Hydroxy-5-methoxyphenyl-Nn-butylaldimine), nickel bis (dithiobenzyl), nickel bis (dithiobiacetyl) and the like.

As quenchers for superoxy anions, superoxide dismutase and cobalt [II
I] and nickel [II] complexes and the like, but these examples do not limit the present invention. These may be used alone or in combination of two or more.

The substrate of the heat-sensitive recording medium of the present invention is a transparent support, and preferably has a refractive index in the range of 1.45 to 1.60 at room temperature. For example, it is common to use a polyester film such as polyethylene terephthalate or polybutylene terephthalate, a cellulose derivative film such as cellulose triacetate, a polyolefin film such as polypropylene or polyethylene, a polystyrene film, or a transparent support obtained by bonding these. is there. It is preferable to provide an adhesive layer between the thermosensitive recording layer. As a material for the adhesive layer, an acrylic resin, a saturated polyester resin, or a resin obtained by curing these is used.

In the heat-sensitive recording medium having no protective layer, since the fine color developer is dispersed in the binder resin, the surface and the inside of the heat-sensitive recording layer become non-uniform, resulting in unevenness and voids in the recording layer. It is opaque because light scattering occurs due to the difference in refractive index between the existing air and the recording layer. However, as in the heat-sensitive recording medium of the present invention, a resin having a refractive index at room temperature in the same range as that of the binder resin of the heat-sensitive recording layer is uniformly applied and dried (cured) on the opaque recording layer. ,
The voids and irregularities of the recording layer are eliminated, and the recording layer is smoothed, light scattering is reduced, and a transparent recording medium is obtained. The protective layer formed here not only contributes to the transparency of the recording medium, but also exerts a great effect on the improvement of chemical resistance, water resistance, abrasion resistance, light resistance, and head matching property. It is indispensable as a component of the thermal recording medium.

The protective layer of the present invention includes a coating formed mainly of a water-soluble resin or a hydrophobic resin, a coating formed mainly of an ultraviolet curable resin or an electron beam curable resin, and the like. By forming such a protective layer, an organic solvent,
A recording medium having no practical problem can be obtained even by contact with a plasticizer, oil, sweat, water, or the like. Further, by containing an organic or inorganic filler and a lubricant, it is possible to obtain a heat-sensitive recording medium excellent in reliability and head matching property without causing a problem such as sticking caused by contact with a thermal head or the like.

Next, the protective layer of the present invention will be described in detail.
As the resin constituting the protective layer of the present invention, a resin having the same refractive index as the binder resin constituting the thermosensitive recording layer is used. Here, the same refractive index means that they are substantially the same, and also includes the case where they are different by about ± 5%. A resin having a refractive index of 1.45 to 1.60 at room temperature is preferable. Examples of such a resin include a water-soluble resin, an aqueous emulsion, a hydrophobic resin, an ultraviolet curable resin, an electron beam curable resin, and the like. Specific examples of the water-soluble resin include, for example, polyvinyl alcohol, modified polyvinyl alcohol, cellulose derivatives (methyl cellulose, methoxy cellulose, hydroxyethyl cellulose, etc.), casein, gelatin, polyvinyl pyrrolidone, styrene-maleic anhydride copolymer, diisobutylene- Maleic anhydride copolymer, polyacrylamide, modified polyacrylamide, methyl vinyl ether-maleic anhydride copolymer, carboxy-modified polyethylene, polyvinyl alcohol / acrylamide block copolymer,
Examples thereof include melamine-formaldehyde resin and urea-formaldehyde resin. Examples of the resin or hydrophobic resin for the aqueous emulsion include polyvinyl acetate, polyurethane, styrene / butadiene copolymer, styrene / butadiene / acrylic copolymer, polyacrylic acid,
Examples thereof include polyacrylic acid ester, vinyl chloride, vinyl acetate copolymer, polybutyl methacrylate, ethylene / vinyl acetate copolymer and the like. These may be used alone or as a mixture, and if necessary, a curing agent may be added to cure the resin.

Next, the most preferable ultraviolet curable resin and electron beam curable resin as the protective layer of the present invention will be described in detail. The UV-curable resin used for forming the protective layer is not limited in kind as long as it is a monomer or oligomer (or prepolymer) which undergoes a polymerization reaction upon irradiation with UV rays and becomes a resin by curing, and various known resins are available. All can be used. Examples of such monomers or oligomers include (poly) ester acrylate, (poly) urethane acrylate, epoxy acrylate, polybutadiene acrylate, silicone acrylate, and melamine acrylate. The (poly) ester acrylate is obtained by reacting a polyhydric alcohol such as 1,6-hexadiol, propylene glycol (as propylene oxide) or diethylene glycol with a polybasic acid such as adipic acid, phthalic anhydride or trimellitic acid and acrylic acid. It is a thing. The structural examples are shown in (a) to (c).

(A) Adipic acid / 1,6-hexadiol / acrylic acid

[Chemical 3] n shows the integer of 1-10. (B) Phthalic anhydride / Propylene oxide / Acrylic acid

[Chemical 4] 1 indicates an integer of 1 to 10. m represents an integer of 1 to 10. n shows the integer of 1-10. (C) Trimet acid / diethylene glycol / acrylic acid

[Chemical 5]

The (poly) urethane acrylate is a compound obtained by reacting an isocyanate-based compound such as tolylene diisocyanate (TDI) with an acrylate having a hydroxy group. An example of the structure is shown in (d).
HEA is 2-hydroxyethyl acrylate, HD
O is an abbreviation for 1,6-hexanediol and ADA is an abbreviation for adipic acid. (D) HEA / TDI / HDO / ADA / HDO / TD
I / HEA

[Chemical 6] n shows the integer of 1-10.

Epoxy acrylates are roughly classified into bisphenol A type, novolac type and alicyclic type according to the structure. Epoxy groups of these epoxy resins are esterified with acrylic acid to make a functional group an acryloyl group.
Examples of the structure are shown in (e) to (g). (E) Bisphenol A-epichlorohydrin type / acrylic acid

[Chemical 7] n: Shows an integer of 1 to 15. (F) Phenol novolac-epichlorohydrin type /
Acrylic acid

[Chemical 8] n: Shows an integer of 0 to 5. (G) Alicyclic / acrylic acid

[Chemical 9] R :-( CH ₂₎ n- are shown, n represents an integer of 1 to 10.

Polybutadiene acrylate has a terminal OH
Isocyanate or 1,2 in group-containing 1,2 polybutadiene
-Mercaptoethanol or the like is reacted, and then acrylic acid or the like is further reacted. Its structural example (h)
Shown in. (H)

[Chemical 10]

The silicone acrylate is, for example, methacryl-modified by a condensation reaction (demethanol reaction) between an organofunctional trimethoxysilane and a silanol group-containing polysiloxane, and its structural example is shown in (i). (I)

[Chemical 11] n shows the integer of 10-14.

When the UV curable resin is used, a solvent may be used. Examples of the solvent in this case include tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, chloroform, carbon tetrachloride, ethanol, isopropyl alcohol, Organic solvents such as ethyl acetate, butyl acetate, toluene and benzene can be mentioned.
Further, instead of these solvents, a photopolymerizable monomer can be used as a reactive diluent for easy handling.

Examples of the photopolymerizable monomer are 2-ethylhexyl acrylate, cyclohexyl acrylate, butoxyethyl acrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, trimethylolpropane triacrylate, pentaeryi. Examples include trit triacrylate.

Next, the electron beam curable resin will be described. The electron beam curable resin is also not particularly limited in type, but a particularly preferable electron beam curable resin is an electron beam curable resin having a branched molecular structure of 5 or more functional groups having a polyester skeleton (hereinafter referred to as “electron beam curable resin”). Acrylic-modified polyurethane resin ") and a silicone-modified electron beam-curable resin are the main components.

The electron beam curable acrylic modified polyurethane resin can be produced, for example, as follows. That is, a reaction product of 1,4-butanediol and adipic acid, or a reaction product of propylene glycol and adipic acid (the above is equivalent to the polyester skeleton) is a mixture of polyesterdiol and polyethertriol. , Diisocyanate and a compound having an acrylic double bond can be added and reacted. Instead of the mixture of polyester diol and polyether triol, for example, a mixture of polyether diol and polyether triol, a mixture of polyester diol and polyester triol, or a mixture of polyether diol and polyester triol is used. Here, as the diisocyanate,
2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,6-hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, methylene bis (4-phenyl isocyanate), etc., also have an acrylic double bond. 2-hydroxyethyl (meth) acrylate as a compound,
2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, etc. can be illustrated. The polyester diol is, for example, ADEKA NEW ACE Y4-30 (manufactured by Asahi Denka Kogyo KK), and the polyether triol is, for example, Sannix TP-40.
0, Sannix GP-3000 (above, Sanyo Chemical Co., Ltd. make) etc. are available.

The molecular weight of the polyester portion of this electron beam-curable acrylic modified polyurethane resin is 200 in order to give the heat-resistant slip layer the flexibility and toughness required.
The range of 0 to 4000 is preferable. Further, the molecular weight of the entire electron beam-curable acrylic modified polyurethane resin is preferably in the range of 20,000 to 50,000 for the same reason as above. In addition, in this resin, effects such as acceleration of curing and improvement of hardness can be brought about by having 5 or more functional groups, preferably 7 to 13 functional groups.

On the other hand, the silicone-modified electron beam curable resin is represented by the following chemical formula 12.

[Chemical 12] (However, in the above formulas, R _{- (CH 2) -n (n} = 0~
3), TDI is 2,4-tolylene diisocyanate, H
EM represents 2-hydroxyethyl acrylate, x =
50-100 y = 3-6. ) Since this silicone-modified electron beam curable resin has excellent coatability, a uniform and thin coat can be formed well,
Further, since it has a silicone functional group, it has an excellent sliding effect.

When the electron beam curable acrylic modified polyurethane resin and the electron beam curable silicone modified resin are used in combination, the ratio is 100 parts by weight of the electron beam curable acrylic modified polyurethane resin and the electron beam curable silicone modified resin. Up to 30 parts by weight of resin, preferably 5-20
It is desirable to add in the range of parts by weight.

In the protective layer of the present invention, in order to accelerate the curing and improve the heat resistance effect during the formation process,
It is desirable to use a multi-sensitive electron beam curable monomer together.
This monomer acts as a cross-linking accelerator and is advantageous in forming a complicated and dense cross-linked structure. Specific examples of such a monomer include trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, pentaerythritol triacrylate, dipentaerythritol hexatriacrylate and the like. Then, it is preferable to add the monomer in an amount of up to 50 parts by weight, preferably 20 to 50 parts by weight, based on 100 parts by weight of the electron beam curable acrylic modified polyurethane resin. If it is more than 50 parts by weight, the lubrication hardening will be weakened and the sliding effect will be reduced.

Another protective layer in the present invention is a phosphazene resin having a repeating unit having a phosphazene skeleton represented by the following chemical formula 13 and is extremely excellent in heat resistance.

[Chemical 13] Specific examples thereof include those represented by Chemical Formula 14 below, but the invention is not limited thereto.

[Chemical 14] A phosphanezen resin represented by Chemical formula 14, for example, a resin in which A is a methacryloyloxyethyl group and b = 0 is
It can be produced by ring-opening polymerization of the compound represented by the following chemical formula 15.

[Chemical 15] In the case of having a polymerization-curable group such as the Bosphanzene-based resin represented by Chemical Formula 14, the mechanical strength, hardness, and heat resistance are further improved by curing with a UV ray, an electron beam, heating or the like.

Similarly to the heat-sensitive recording layer, the protective layer of the present invention also comprises
A light stabilizer can be added to improve light resistance. As the light stabilizer used in the present invention, an ultraviolet absorber, an antioxidant, an antioxidant, a quencher for singlet oxygen,
It is a quencher of superoxide anion, and the same ones as those used in the heat-sensitive recording layer are used.

Further, the improvement of the head matching property of the heat-sensitive recording medium of the present invention is achieved by incorporating an organic or inorganic filler and a slip additive into the protective layer to the extent that transparency is not deteriorated. Examples of the organic filler used in the present invention include polyolefin particles, polystyrene particles, urea-formaldehyde resin particles, or plastic micro hollow sphere particles.As the inorganic filler, aluminum hydroxide, heavy and light calcium carbonate, Zinc oxide, titanium oxide, barium sulfur, silica gel, colloidal silica (10 to 50 μm), alumina sol (10 to 10 μm)
200 μm), activated clay, talc, clay titanium white, kaolinite, calcined kaolinite, diatomaceous earth, synthetic kaolinite, zirconium compounds, glass micro hollow spheres, and the like, and particularly the shape of the filler is spherical,
A material having lubricity such as Si resin or fluororesin is preferable. Examples of the lubricity additive include silicone oil, surfactants, lubricants such as organic salts and waxes, and lubricant fillers. Examples of the silicone oil include dimethylpolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, alkyl-modified polysiloxane, amino-modified polysiloxane, carboxyl-modified polysiloxane, alcohol-modified polysiloxane and the like.

Examples of the surfactant include carboxylic acid salts, sulfuric acid ester salts of higher alcohols, sulfonic acid salts, phosphoric acid esters of higher alcohols and salts thereof which are usually commercially available. Specific examples of these compounds include sodium laurate, sodium stearate, sodium oleate, sodium lauryl alcohol sulfate, sodium myristyl alcohol sulfate, sodium cetyl alcohol sulfate, sodium stearyl alcohol sulfate, sodium oleyl alcohol sulfate. Sodium sulfate ester of ethylene oxide adduct of higher alcohol, sodium octyl sulfonate, sodium decyl sulfonate, sodium dodecyl sulfonate, sodium octyl benzene sulfonate, sodium dodecyl benzene sulfonate, potassium dodecyl benzene sulfonate, nonylnaphthalene sulfonic acid Sodium, sodium dodecylnaphthalene sulfonate, dodecylna Examples thereof include potassium talensulfonate, sodium N-oleoyl-N-methyltaurine, tetraethoxylauryl alcohol ester, sodium monostearyl ester phosphate, and sodium distearyl ester phosphate, but are not limited thereto. is not.

The organic salts include, for example,
Examples thereof include metal soaps such as zinc stearate, aluminum stearate, calcium stearate and magnesium stearate, and salts such as hexyl ammonium chloride, sodium sulfosalicylate, sodium succinate, potassium succinate, potassium benzoate and potassium adipate.

As the waxes, natural waxes such as candelilla wax, carnauba wax, rice wax, beeswax, lanolin wax, montan wax, paraffin wax, microcrystalline wax, synthetic waxes such as polyethylene wax, hydrogenated castor oil or its derivatives, Examples thereof include fatty acid amides. The amount of the lubricant in the protective layer is 0.001 to 15.
0 wt% is suitable. If it is more than this range, the mechanical strength of the protective layer is poor, and if it is less than this range, the effect of the lubricant is lost.

In the transparent heat-sensitive recording medium of the present invention, only the color developer is uniformly dispersed in an organic solvent, and a color-developing agent and a binder resin are sequentially mixed to prepare a coating solution for the heat-sensitive recording layer, or an organic solvent is used. A developer is uniformly dispersed in a binder resin solution in which a binder resin is dissolved, and a color-forming agent or the like is uniformly mixed to prepare a thermal recording layer coating liquid, or the color-forming agent and the developer are combined with a binder resin in an organic solvent. To prepare a coating solution for heat-sensitive recording layer, or to apply a coating solution uniformly dispersed by any method onto one side or both sides of a transparent support to form a heat-sensitive recording layer, and further It is manufactured by providing a protective layer containing a resin as a main component. In addition, a transparent thermosensitive recording medium capable of forming a two-color image can be produced by providing a thermosensitive recording layer that develops different colors on both surfaces of the transparent support and a protective layer on the thermosensitive recording layer.

As the organic solvent for dissolving the binder resin, dibutyl ether, isopropyl ether, dioxane, ethers such as tetrahydrofuran, acetone,
Ketones such as diethyl ketone, methyl ethyl ketone, methyl isobutyl ketone, and methyl propyl ketone, ethyl acetate, isopropyl acetate, n-propyl acetate, n-acetate
Esters such as butyl and aromatic hydrocarbons such as benzene, toluene and xylene may be used alone or in combination.

Although there is no particular limitation on the coating method and coating amount of the protective layer, the coating amount of the coating layer on the recording medium is 0.1-0.1 in view of the performance and economical efficiency of the protective layer. 20
μm range, more preferably 0.5 to 10 μm
Within the range, the thickness range is such that the performance as the protective layer is sufficiently exhibited and the performance of the recording medium is not deteriorated.

The formation of a recorded image on the transparent thermosensitive recording medium of the present invention varies depending on the purpose of use, but is not particularly limited to thermal pen, thermal head, laser heating, thermal etching using light, and the like. However, practically, image formation by a thermal head is useful.

Next, a method for forming an image using the transparent thermosensitive recording medium in which the thermosensitive recording layers are provided on both surfaces of the transparent support of the present invention will be described with reference to FIGS. First, the transparent thermosensitive recording medium of the present invention comprises a transparent support 1, thermosensitive recording layers 2 and 3 and protective layers 4 provided on both sides of the support 1.
It is composed of 5. Examples of the method for forming an image using this transparent thermosensitive recording medium include the following methods.

Image forming method (1)-(shown in FIG. 1) Step (A) The support 7 is provided on one side of the transparent thermosensitive recording medium on the thermosensitive recording layer 2 side.
A normal image original 13 on which an image 6 containing carbon black is formed is superposed, and flash light, strong white light or the like is emitted from a lamp 8 from the direction of the transparent thermosensitive recording medium to contain the carbon black of the normal image original 13. The carbon black portion of the image is heated, and the generated heat causes the thermal recording layer 2 to be partially thermally etched to form a color image (a) 9. Step (B) Next, from the thermosensitive recording layer 3 side of the transparent thermosensitive recording medium, a color image (b) 11 is formed using the thermal head 10. As described below, the two-color images (a) and (b) can be formed by the steps (A) and (B).

Image forming method (2)-(shown in FIG. 2) Step (C) A normal image original on which an image containing carbon black is formed on a support 7 on the side of the thermosensitive recording layer 2 on one side of a transparent thermosensitive recording medium. 1
3 are overlaid and the lamp 8 is attached from the direction of the transparent thermosensitive recording medium.
The flash image, strong white light, etc. are radiated with
The carbon black portion of the image containing the carbon black is heated, and the generated heat causes the thermal recording layer 2 to be partially thermally etched to form a colored image (a) 9. Step (D) Next, on the other side of the heat-sensitive recording layer 3 of the transparent heat-sensitive recording medium, the reverse image original 14 on which the image 6 containing carbon black is formed on the support 7 is superposed, and the same as step C below. The colored image (c) 12 is formed. As described above, the two-color images (a) and (c) can be formed by the steps (C) and (D).

Image forming method (3)-(shown in FIG. 3) Step (E) From the thermosensitive recording layer 3 side of the transparent thermosensitive recording medium, a colored image (b) 11 is formed using the thermal head 10. Step (F) Next, a colored image (d) 15 is formed using the thermal head 10 from the side of the thermosensitive recording layer 2 of the transparent thermosensitive recording medium. As described above, the two-color images (b) and (d) are formed by the steps (E) and (F).

Hereinafter, the present invention will be described in more detail with reference to examples. In the following, all parts and% are based on weight.

Example 1 3- (N-n-propyl-N-methylamino) -6-methyl-7-anilinofluorane 10 parts Octadecylphosphonic acid 30 parts Ethyl cellulose (refractive index 1.47 manufactured by Kanto Chemical Co., Inc.) 15 parts Toluene 140 parts Methylethylketone 145 parts The above composition is put in a sample bottle together with stainless balls and dispersed for 48 hours with a tabletop pole mill to disperse octadecylphosphonic acid to an average particle size of about 3 μm. The dispersion prepared as described above was further applied onto a surface-treated surface of a 100 μm single-sided easy-adhesive transparent polyester film (Teijin Tetoron film: HPJ) using a wire bar so that an application thickness was 5.5 μm, and dried. Then, a thermal recording medium was prepared. Further, a protective layer coating solution having the following composition was coated on the thermosensitive recording layer using a wire bar to a coating thickness of 4.5 μm.
A transparent thermosensitive recording medium was prepared by coating and drying so that [Protective Layer Coating Liquid] A mixture having the following composition was thoroughly pulverized and dispersed by a ball mill to prepare a protective layer coating liquid. Acrylic emulsion (refractive index 1.49) 60 parts (John Cryl 390 manufactured by Johnson Co.) Epichlorohydrin / polyamide copolymer 10% aqueous solution 20 parts Colloidal silica (10 mμm to 50 mμm) 2 parts

Example 2 3-Diethylamino-6-methyl-7-anilinofluorane 10 parts Octadecylphosphonic acid 30 parts Polyvinyl butyral (refractive index 1.49 manufactured by Denki Kagaku Kogyo Co., Ltd. 15 parts Denkabutyral # 3000-2) toluene 140 parts Methyl ethyl ketone 145 parts The above composition was put in a sample bottle together with a stainless ball and dispersed for 48 hours with a tabletop pole mill to disperse octadecylphosphonic acid to an average particle size of about 3 μm. The dispersion prepared as described above was further applied to the surface treatment of a 100 μm single-sided easy-adhesive transparent polyester film (Teijin Tetoron film: HPJ) using a wire bar so that the coating thickness was 5.5 μm, and dried. To prepare a thermal recording medium. Further, a protective layer coating solution having the following composition was applied onto the thermosensitive recording layer using a wire bar, heated and dried, and then cured with an 80 W / cm ultraviolet lamp to provide a protective layer having a thickness of about 5 μm to form a transparent thermosensitive recording medium. Was produced. [Protective Layer Coating Liquid] A mixture having the following composition was dispersed to prepare a protective layer coating liquid. 75% butyl acetate solution of urethane acrylate UV curable resin (refractive index 1.56) (Unidick C7-157 manufactured by Dainippon Ink and Chemicals, Inc. 100 parts) 52% xylene solution of silicon resin 4.3 parts (Pick Chemie Japan Byk-344 manufactured by the company) 50 parts ethyl acetate

Example 3 3-Diethylamino-6-methyl-7- (2 ', 4'-dimethylanilino) fluorane 10 parts Eicosylphosphonic acid 30 parts Polyvinyl butyral 15 parts (refractive index 1.48 manufactured by Sekisui Chemical Co., Ltd. S-REC BX-1) Toluene 140 parts Methyl ethyl ketone 145 parts The above composition was put in a sample bottle together with a stainless ball and dispersed for 48 hours on a tabletop pole mill to disperse the eicosylphosphonic acid to an average particle size of about 2 μm. The dispersion prepared as described above was further applied to a 100 μm single-sided easily-adhesive transparent polyester film (Teijin Tetoron film: HPJ) using a wire bar to give a coating thickness of 5.5.
A thermosensitive recording medium was prepared by coating and drying so as to have a thickness of μm. Further, a coating solution for protective layer having the following composition was applied on the heat-sensitive recording layer using a wire bar, and after heating and drying, 80 W / cm.
Was cured with an ultraviolet lamp of No. 1 and a protective layer having a thickness of about 5 μm was provided to prepare a transparent thermosensitive recording medium. [Protective Layer Coating Liquid] A mixture having the following composition was dispersed to prepare a protective layer coating liquid. Polyphosphazene resin (refractive index 1.59, AC-101 manufactured by Idemitsu Petrochemical Co., Ltd.) 100 parts 50% xylene solution of silicon resin 2 parts (Byk-300 manufactured by Pick Chemie Japan)

Example 4 3- (N-isoamyl-N-ethylamino) -7,8-benzfluorane 10 parts Octadecylphosphonic acid 30 parts Polyvinyl butyral (refractive index 1.49 manufactured by Denki Kagaku Kogyo Co., Ltd. 15 parts Denka Butyral # 3000-2) 2- (2'-hydroxy-5'-methylphenyl) benzotriazole 1 part 2,6-ditertiarybutyl-4-methylphenol 0.5 part Toluene 140 parts Methylethylketone 145 parts The above composition Put together with stainless balls in a sample bottle and disperse for 48 hours with a tabletop ball mill to disperse octadecylphosphonic acid to an average particle size of about 3 μm. The dispersion prepared as described above was further applied onto a surface-treated surface of a 100 μm single-sided easy-adhesive transparent polyester film (Teijin Tetoron film: HPJ) using a wire bar so that an application thickness was 5.5 μm, and dried. Then, a thermal recording medium was prepared. Further, a protective layer coating solution having the following composition was applied onto the thermosensitive recording layer using a wire bar, heated and dried, and then cured with an 80 W / cm ultraviolet lamp to provide a protective layer having a thickness of about 5 μm to form a transparent thermosensitive recording medium. Was produced. [Protective Layer Coating Liquid] A mixture having the following composition was thoroughly pulverized and dispersed by a ball mill to prepare a protective layer coating liquid. 75% butyl acetate solution of urethane acrylate UV curable resin 100 parts (refractive index 1.56 Unidick C7-157 manufactured by Dainippon Ink and Chemicals) Calcium carbonate (callite SA manufactured by Shiraishi Calcium Co.) 1 part Zinc stearate 1 part Toluene 50 parts

Example 5 3-Diethylamino-7-anilinofluorane 10 parts Docosylphosphonic acid 30 parts Polyvinyl butyral (15 parts Denki Butyral # 4000-2 manufactured by Denki Kagaku Kogyo Co.) P-tert-butyl phenyl salicylate 1 part 2,4,6-Tri-tert-butylphenol 0.5 parts Toluene 140 parts Methylethylketone 145 parts The above composition was put in a sample bottle together with a stainless ball and dispersed for 48 hours with a tabletop pole mill to give an average particle size of docosylphosphonic acid. Disperse to about 2 μm. The dispersion liquid prepared as described above was further applied to a transparent polyester film of 100 μm using a wire bar to give a coating thickness of 5.5.
A thermosensitive recording medium was prepared by coating and drying so as to have a thickness of μm. Further, a coating solution for protective layer having the following composition was applied on the heat-sensitive recording layer using a wire bar, and after heating and drying, 80 W / cm.
Was cured with an ultraviolet lamp of No. 1 to provide a protective layer having a thickness of about 6 μm to prepare a transparent thermosensitive recording medium. [Protective Layer Coating Liquid] A mixture having the following composition was dispersed to prepare a protective layer coating liquid. 75% butyl acetate solution of urethane acrylate UV curable resin (Dainippon Ink and Chemicals, Inc. 100 parts Unidick 17-824-9) Amino-modified silicone oil 1 part (Shin-Etsu Chemical F867) Ethyl acetate 50 parts

Example 6 3,6-bis (diphenylamino) fluorane 8 parts Octadecylphosphonic acid 30 parts Polyvinyl butyral (15 parts Denkabutyral # 2000-L manufactured by Denki Kagaku Kogyo Co.) 2- (2'-hydroxy-3 ') , 5'-Ditertiarybutylphenyl) benzotriazole 1 part 2,4,6-tritertiarybutylphenol 0.5 part Toluene 140 parts Methylethylketone 145 parts The above composition was put in a sample bottle together with a stainless steel ball, and a tabletop pole mill was used. Disperse over time and disperse octadecylphosphonic acid to an average particle size of about 3 μm. The dispersion liquid prepared as described above was further applied to a transparent polyester film having a thickness of 100 μm using a wire bar so as to have a coating thickness of 5.5 μm, and dried to prepare a thermosensitive recording medium. Further, a protective layer coating solution having the following composition was coated on the heat-sensitive recording layer using a wire bar, and after heating and drying, 80 W
A transparent thermosensitive recording medium was prepared by curing with a UV lamp of / cm and providing a protective layer having a thickness of about 6 μm. [Protective Layer Coating Liquid] A mixture having the following composition was dispersed to prepare a protective layer coating liquid. 75% butyl acetate solution of urethane acrylate UV-curable resin 100 parts (refractive index 1.56, Unidick C7-157, manufactured by Dainippon Ink and Chemicals, Inc.) 52% xylene solution of silicone resin 4.3 parts (Pick Chemie Japan, Inc. Byk-344) Ethyl acetate 50 parts

Example 7 3-Diethylamino-6-methyl-7-anilinofluorane 10 parts Eicosylphosphonic acid 30 parts Polyvinyl butyral (15 parts Denka Formal # 100 manufactured by Denki Kagaku Kogyo Co.) 2- (2'-hydroxy) -3 ', 5'-ditertiarybutylphenyl) benzotriazole 1 part 2,4,6-tritertiarybutylphenol 0.5 part Toluene 140 parts Methylethylketone 145 parts The above composition was put in a sample bottle together with a stainless ball and placed in a tabletop type. Disperse with a pole mill for 48 hours, and disperse the eicosylphosphonic acid to an average particle size of about 2 μm. 4. The dispersion prepared as described above was further applied to a transparent polyester film of 100 μm using a wire bar to give a coating thickness of 5.
A thermosensitive recording medium was prepared by coating and drying so as to have a thickness of 5 μm. Further, a protective layer coating solution having the following composition was coated on the heat-sensitive recording layer using a wire bar, and after heating and drying, electron beam irradiation (1M rad) was applied to cure the solution, and then about 4. A transparent thermosensitive recording medium was prepared by providing a protective layer having a thickness of μm. [Protective Layer Coating Liquid] A mixture having the following composition was dispersed to prepare a protective layer coating liquid. Electron beam curable acrylic-modified polyurethane resin 10 parts [Adeka New Ace Y4-30 manufactured by Asahi Denka Kogyo Co., Ltd. whose polyester part has a molecular weight of about 3000 and polyester triol TP-400 (manufactured by Sanyo Kasei) and 2,6-tolylene diisocyanate A reaction product having a branched structure of hydroxyethyl acrylate; 10 functional groups, total molecular weight of about 30,000] Polyfunctional monomer (M-8030 manufactured by Toagosei Kasei Co., Ltd.) 3 parts Silicone-modified urethane acrylate 2 parts ( US Freeman 19-4842) 50 parts MEK / toluene (1/1) mixed solution

Example 8 3-diethylamino-6-methyl-7-anilinofluorane 10 parts α-hydroxyoctadecylphosphonic acid 30 parts polyvinyl butyral 15 parts (refractive index 1.49 Denka Butyral # 3000 manufactured by Denki Kagaku Kogyo KK) -2) Toluene 140 parts Methyl ethyl ketone 145 parts The above composition is put into a sample bottle together with a stainless ball and dispersed for 48 hours with a tabletop ball mill to disperse the average particle size of α-hydroxyoctadecylphosphonic acid to about 3 μm. The dispersion liquid prepared as described above is further added to 10
A thermosensitive recording medium was prepared by coating a 0 μm transparent polyester film with a wire bar to a coating thickness of 5.5 μm and drying. Further, a protective layer coating solution having the following composition was applied onto the thermosensitive recording layer using a wire bar, heated and dried, and then cured with an 80 W / cm ultraviolet lamp to provide a protective layer having a thickness of about 5 μm to form a transparent thermosensitive recording medium. Was produced. [Protective Layer Coating Liquid] A mixture having the following composition was dispersed to prepare a protective layer coating liquid. 100 parts Urethane acrylate diameter 75% butyl acetate solution of UV curable resin (refractive index 1.56 Unidick C7-157 manufactured by Dainippon Ink and Chemicals) 52% xylene solution of silicone resin 4.3 parts (Pick Chemie Japan Byk-344) Ethyl acetate 50 parts

Example 9 3- (N-iso-butyl-N-ethylamino) 6.7 parts -7,8-benzofluorane 3,6-bis (diphenylamino) fluorane 3.3 parts α-hydroxyeico Sylphosphonic acid 30 parts Polyvinyl butyral 15 parts (refractive index 1.48, S-REC BX-1 manufactured by Sekisui Chemical Co., Ltd.) Toluene 140 parts Methyl ethyl ketone 145 parts The above composition was put in a sample bottle together with stainless steel balls and dispersed for 48 hours with a tabletop ball mill. , Α-hydroxyeicosylphosphonic acid having an average particle size of about 2 μm is dispersed. The dispersion liquid prepared as described above is further added to 10
A thermosensitive recording medium was prepared by coating a 0 μm transparent polyester film with a wire bar so that the coating thickness was 5.5 μm, and drying. Further, a protective layer coating solution having the following composition was coated on the heat-sensitive recording layer by using a wire bar, dried by heating, and then cured by an 80 W / cm ultraviolet lamp to give about 5 μm.
A transparent protective recording medium was prepared by providing a thick protective layer. [Protective Layer Coating Liquid] A mixture having the following composition was dispersed to prepare a protective layer coating liquid. Polyphosphazene resin 100 parts (refractive index 1.59, AC-101 manufactured by Idemitsu Petrochemical Co., Ltd.) 50% xylene solution of silicon resin 2 parts (Byk-300 manufactured by Pick Chemie Japan)

Example 10 3-Diethylamino-6-methyl-7- (2 ', 4'-dimethylanilino) fluorane 10 parts Gallic acid stearyl ester 30 parts Polyvinyl butyral 15 parts (refractive index 1.48 manufactured by Sekisui Chemical Co., Ltd. S-REC BX-1) Toluene 240 parts Cyclohexane 45 parts The above composition was put into a sample bottle together with stainless steel balls and dispersed for 48 hours with a tabletop ball mill to disperse an average particle size of stearyl gallate to about 2 μm.
The dispersion prepared as described above was further applied to a 100 μm double-sided easy-adhesive transparent polyester film (ICI Japan Melinex 505) using a wire bar so that the coating thickness was 5.5 μm, and dried to obtain a thermosensitive recording medium. Was produced. Further, a protective layer coating solution having the following composition was coated on the heat-sensitive recording layer using a wire bar, and after heating and drying, 80 W
A transparent thermosensitive recording medium was prepared by curing with a UV lamp of 1 cm / cm and providing a protective layer having a thickness of about 5 μm. [Protective Layer Coating Liquid] A mixture having the following composition was dispersed to prepare a protective layer coating liquid. Polyphosphazene resin 100 parts (refractive index 1.59, AC-101 manufactured by Idemitsu Petrochemical Co., Ltd.) 50% xylene solution of silicon resin 2 parts (Byk-300 manufactured by Pick Chemie Japan)

Example 11 3- (N-iso-amyl-N-ethylamino) -7,8-benzfluorane 10 parts Octadecylphosphonic acid 30 parts Acrylic resin 15 parts (refractive index 1.49 DYNAL manufactured by Mitsubishi Rayon Co., Ltd.) BR-85) 2- (2'-hydroxy-5'-methylphenyl) benzotriazole 1 part 2,6-ditertiary-butyl-4-methylphenol 0.5 part Toluene 140 parts Methoruethylketone 145 parts The above composition is stainless steel. Put together with the balls in a sample bottle and disperse for 48 hours with a tabletop ball mill to disperse octadecylphosphonic acid to an average particle size of about 3 μm. The dispersion prepared as described above was further applied to a 100 μm double-sided easy-adhesive transparent polyester film (ICI Japan Melinex 705) using a wire bar to give a coating thickness of 5.5.
A thermosensitive recording medium was prepared by coating and drying so as to have a thickness of μm. Further, a coating solution for protective layer having the following composition was applied on the heat-sensitive recording layer using a wire bar, and after heating and drying, 80 W / cm.
Was cured with an ultraviolet lamp of No. 1 and a protective layer having a thickness of about 5 μm was provided to prepare a transparent thermosensitive recording medium. [Protective Layer Coating Liquid] A mixture having the following composition was thoroughly pulverized and dispersed by a ball mill to prepare a protective layer coating liquid. 75% butyl acetate solution of urethane acrylate-based UV curable resin 100 parts (refractive index 1.56, Unidick C7-157, manufactured by Dainippon Ink and Chemicals, Inc.) Calcium carbonate (callite SA, manufactured by Shiraishi Calcium Co., Ltd.) 1 part, zinc stearate 1 part, toluene 50 copies

Example 12 3-Diethylamino-6-methyl-7-anilinofluorane 10 parts Octadecylphosphonic acid 30 parts Polyvinyl butyral (refractive index 1.49 electrochemistry 15 parts Industrial Denka Butyral # 3000-2) 2 -(2'-Hydroxy-3 ', 5'-ditertiary-butyl-phenyl) benzotriazole 0.5 part 2,4,6-tritertiary-butylphenol 0.5 part Toluene / metholethylketone (1/1) mixture 285 parts The above composition was dispersed by a table-top ball mill to obtain octadecylphosphonic acid having an average particle size of 3 μm (excluding particles having a particle size of 1 μm or more), to prepare a coating liquid for forming a thermosensitive recording layer. A 100 μm double-sided easy-adhesive transparent polyester film (Teijin Tetoron film: HMW) was coated with a coating solution for forming a recording layer using a wire bar to a coating thickness of 5.0 μm and dried to form a thermosensitive recording medium. Further, a protective layer coating solution having the following composition was applied onto the thermosensitive recording layer using a wire bar, heated and dried, and then cured with an 80 W / cm ultraviolet lamp to form a protective layer having a thickness of about 3 μm, thereby providing a transparent thermosensitive recording medium. Was produced. [Protective Layer Coating Liquid] The following composition was uniformly dispersed to prepare a protective layer forming coating liquid. 75% butyl acetate solution of urethane acrylate UV curable resin 100 parts (refractive index 1.56 Unidick C7-157 manufactured by Dainippon Ink and Chemicals) 52% xylene solution of silicon resin 4 parts (Byk-344 manufactured by BYK Japan KK) ) Ethyl acetate 50 parts

Comparative Example 1 A thermosensitive recording medium of Comparative Example 1 was prepared in the same manner as in Example 1 except that the protective layer of Example 1 was omitted.

Comparative Example 2 Instead of the polyvinyl butyral of Example 2, vinyl chloride was used.
Vinyl acetate copolymer (Made by Union Carbide: VYH
A thermal recording medium of Comparative Example 2 was produced in the same manner as in Example 2 except that H) was used.

Comparative Example 3 Instead of the urethane acrylate-based UV-curable resin used in the protective layer of Example 2, a polysulfone resin (having a refractive index of 1.
Comparative Example 3 was carried out in the same manner as in Example 2 except that 63) was used.
A heat-sensitive recording medium of was prepared.

The heat-sensitive recording medium produced as described above was applied to a printing apparatus using a thermal head of 8 dots / mm, with an applied power of 1.0 W and an applied pulse width of 0.9 msec.
The applied energy was applied to record an image, and the following evaluation test was performed. The results are shown in Table 1. "Color tone" The color tone immediately after recording was visually observed. "Transmission Density" The image density and background density immediately after recording are measured by a transmission densitometer X-Rite310TR (XRITE COMPAN).
(Made by Y). "Transparency" 1) The transparency of the transparent thermosensitive recording medium is changed to Ricoh reflection type OHP3.
The brightness (illuminance) was measured by actually projecting with 12R. For comparison, a transparent PET film of 100 μm (Lumirror T type manufactured by Toray Industries, Inc.) was used, and the illuminance was 489 Lux. 2) The transparency of the transparent thermosensitive recording medium was evaluated by the spectral transmittance. Shimadzu UV-3100 was used as the spectrophotometer, and the spectral wavelength was 570 mm. "Storability" 1) Heat resistance ... Stored at 40 ° C Dry for 24 hours, and the densities of the image part and the background part were measured and evaluated. 2) Light resistance: The sample was exposed to a 5000 Lux fluorescent lamp for 120 hours, and the densities of the image part and the background part were measured and evaluated. "Chemical resistance" Attach ethyl alcohol to the recording medium,
It was left for 15 minutes at room temperature (24 ° C.) and visually evaluated for stability. "Running property" The running property (head matching property) when an image was recorded on the recording medium by the printing device was evaluated. The chemical resistance and the running property were evaluated according to the following evaluation criteria. "Evaluation criteria" 〇 Excellent △ Good × Inferior

[0068]

[Table 1]

Example 13 [Coating liquid A for recording layer formation] The following composition was sufficiently dispersed by a ball mill to prepare octadecylphosphonic acid so that the average particle size thereof was about 0.3 μm, and a recording element formation residual coating was carried out. Liquid A was prepared. 3-Diethylamino-6-methyl-7-anilinofluorane 10 parts Octadecylphosphonic acid 30 parts Polyvinyl butyral 15 parts (Refractive index 1.49 Denka Butyral # 3000-2 manufactured by Denki Kagaku Kogyo Co., Ltd.) Toluene / methyl ethyl ketone (1/1) ) Liquid mixture 285 parts [Coating liquid B for recording layer formation] The following composition was sufficiently dispersed in a ball mill to prepare an octadecylphosphonic acid having an average particle size of about 0.3 µm. B was produced. 3- (N-iso-butyl-N-ethylamino) -7,8-benzfluorane 10 parts Octadecylphosphonic acid 30 parts Polyvinyl butyral 15 parts (Refractive index 1.49 Denka Butyral # 3000-2 manufactured by Denki Kagaku Kogyo KK) ) Toluene / methyl ethyl ketone (1/1) mixed liquid 285 parts [Coating liquid for forming protective layer] Disperse the following composition uniformly,
A coating liquid for forming a protective layer was prepared. Urethane acrylate diameter 75% butyl acetate 100 parts of UV curable resin solution (refractive index 1.56 Unidick C7-157 manufactured by Dainippon Ink and Chemicals) 52% xylene solution of silicon resin 3 parts (Byk-manufactured by BYK Japan KK) 344) Ethyl acetate 50 parts [Preparation of transparent heat-sensitive recording medium] 100 μm double-sided easy-adhesive transparent polyester film (ICI Japan Melinex 705) Coating solution A for recording layer formation was applied on the A side using a wire bar to a thickness of 5.5 μm. And dried to obtain a recording layer-forming coating liquid B on the surface of the transparent polyester film B using a wire bar to a coating thickness of 5.5 μm.
And the coating layer were dried to form recording layers on both sides. Further, the coating solution for forming the protective layer is sequentially applied onto the recording layers on both sides using a wire bar, and after heating and drying, 80 W /
It is cured with a 3 cm UV lamp, and each side has about 3μ
A m-thick protective layer was provided to prepare a transparent thermosensitive recording medium.

Example 14 [Recording Layer Forming Coating Liquid A] The following composition was sufficiently dispersed in a ball mill to prepare octadecylphosphonic acid so that the average particle size thereof was about 0.3 μm, and a recording element forming coating was prepared. Liquid A was prepared. 3,6-Bis (diphenylamino) fluoran 10 parts Octadecylphosphonic acid 30 parts Polyvinyl butyral 15 parts (refractive index 1.49 Denkabutyral # 3000-2 manufactured by Denki Kagaku Kogyo Co., Ltd.) Toluene / methyl ethyl ketone (1/1) mixture 285 Part [Coating liquid B for forming recording layer] The following composition was sufficiently dispersed by a ball mill so that the average particle diameter of eicosylphosphonic acid was 0.
Coating solution B for forming recording layer prepared to have a thickness of about 2 μm
Was produced. 3- (N-iso-amyl-N-ethylamino) -7,8-benzfluorane 10 parts Eicosylphosphonic acid 30 parts Polyvinyl butyral 15 parts (refractive index 1.49 manufactured by Denki Kagaku Kogyo Denka Blair # 3000). -2) Toluene / methyl ethyl ketone (1/1) mixed liquid 285 parts [Protective layer forming coating liquid] Disperse the following composition uniformly,
A coating liquid for forming a protective layer was prepared. Urethane acrylate diameter 75% butyl acetate 100 parts solution of UV curable resin (refractive index 1.56 Unidick C7-157 manufactured by Dainippon Ink and Chemicals) 52% xylene solution of silicon resin 3 parts (Byk-344 manufactured by BYK Japan KK) ) Ethyl acetate 50 parts [Preparation of transparent thermosensitive recording medium] 100 μm double-sided easy-adhesive transparent polyester film (Teijin Tetoron film: H7W) Coating liquid A for recording layer formation was applied on the A side using a wire bar to a thickness of 5.5 μm. And dried to obtain a recording layer-forming coating liquid B on the surface of the transparent polyester film B using a wire bar to a coating thickness of 5.5 μm.
And the coating layer were dried to form recording layers on both sides. Further, the coating solution for forming the protective layer is sequentially applied onto the recording layers on both sides using a wire bar, and after heating and drying, 80 W /
The film was cured with an ultraviolet lamp of cm to obtain protective layers each having a thickness of about 3 μm on both sides, and a transparent thermosensitive recording medium was prepared.

Application Example 1 The surface A of the transparent thermosensitive recording medium of Example 12 and the normal image original prepared by the PPC copying machine are superposed and 3M Transparency Make is applied.
R (manufactured by 3M) was used to apply a strong light from the transparent thermosensitive recording medium B side to record a black image on the recording medium A side. Then, a red normal image was recorded on the surface B of the recording medium by a thermal transfer printer (NL-1 printer manufactured by Ricoh Co., Ltd.) using a thermal head to form a two-color image of black and red.

Application Example 2 The transparent thermosensitive recording medium A side of Example 14 and the normal image original prepared by the PPC copying machine are superposed on each other, and 3M Transparency Make is applied.
R (manufactured by 3M) was used to irradiate the transparent thermosensitive recording medium B surface with strong light to record a blue image on the recording medium A surface. Then, the surface B of the recording medium and the reverse image original prepared by the PPC copying machine are superposed on each other, and 3M Transparency Maker (manufactured by 3M Company)
A strong red light was applied from the recording medium A side to record a red image on the recording medium B side to form a two-color image of blue and red.

Application Example 3 On the surface A of the transparent heat-sensitive recording medium of Example 12, a black transfer image using a thermal head (a printer for personal word processor NL-1 manufactured by Ricoh Co., Ltd.) was used to record a black normal image.
Next, a reverse image image of red was recorded on the surface of the recording medium B using a thermal transfer printer using the same thermal head, and two-color images of black and red were formed.

[0074]

The transparent thermosensitive recording medium of the present invention is provided with a thermosensitive recording layer and a protective layer having the same refractive index on a transparent support, so that the refractive index at room temperature is 1.45 to 1 in particular. .6
By providing a heat-sensitive recording layer using a binder resin having a hydroxyl group of 0 and a protective layer containing a resin having a refractive index of 1.45 to 1.60 at room temperature as a main component in order and making them transparent,
Further, by containing the necessary additives in the recording layer and the protective layer, the preservability, chemical resistance and running property are excellent. These transparent thermosensitive recording media are particularly useful as an image forming film for OHP and an image forming film for CAD.

[Brief description of drawings]

FIG. 1 is a process drawing showing a two-color image forming method using a transparent thermosensitive recording medium of the present invention.

FIG. 2 is a process drawing showing another two-color image forming method using the transparent thermosensitive recording medium of the present invention.

FIG. 3 is still another 2 using the transparent thermosensitive recording medium of the present invention.
6A to 6C are process diagrams showing a color image forming method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent support 2 Thermal recording layer 3 Thermal recording layer 4 Protective layer 5 Protective layer 6 Image containing carbon black 7 Support 8 Lamp 9 Color image (a) 10 Thermal head 11 Color image (b) 12 Color image (c) 13 Normal image original 14 Reverse image original 15 Color image (d)

Claims (11)

[Claims] 1. A heat-sensitive recording layer containing an electron-donating color-forming compound, an electron-accepting compound and a binder resin as a main component is provided on a transparent support, and a protective layer is further provided on the heat-sensitive recording layer. A transparent heat-sensitive recording medium, wherein the heat-sensitive recording layer and the protective layer have the same refractive index. 2. The transparent recording medium according to claim 1, wherein the transparent support has the same refractive index as that of the heat-sensitive recording layer and the protective layer. 3. The refractive index of the binder resin at room temperature,
And the refractive index of the resin constituting the protective layer at room temperature is
2. The transparent thermosensitive recording medium according to claim 1, which is 1.45 to 1.60. 4. The transparent thermosensitive recording medium according to claim 1, wherein the electron-accepting compound is an organic phosphorus compound. 5. The organic phosphorus compound has the following general formula:
(I) (Chemical Formula 1) or general formula (II) (Chemical Formula 2)
A transparent material according to claim 4, which is a phosphonic acid.
Thermal recording medium. [Chemical 1] (In the formula, R represents a linear alkyl group having 16 to 24 carbon atoms.
Forget ) [Chemical 2](In the formula, R'is a linear alkyl group having 13 to 23 carbon atoms.
Represent. ) 6. The average particle size of the electron-accepting compound is:
The transparent thermosensitive recording medium according to claim 1 or 2, which has a thickness of 10 µm or less. 7. The transparent thermosensitive recording medium according to claim 1, wherein the binder resin is a resin having a hydroxyl group in the molecule. 8. A light stabilizer selected from an ultraviolet absorber, an antioxidant, an antioxidant, a singlet oxygen quencher, and a superoxide anion quencher in the heat-sensitive recording layer and / or the protective layer. 2. The transparent heat-sensitive recording medium according to claim 1, containing one or more of the above. 9. The transparent thermosensitive recording medium according to claim 1, wherein the protective layer is made of an ultraviolet ray or electron beam curable resin, and a slip additive is contained in the protective layer. 10. On each of both surfaces of the transparent support,
The transparent thermosensitive recording medium according to claim 1, wherein a thermosensitive recording layer and a protective layer are sequentially provided. 11. The transparent thermosensitive recording medium according to claim 10, wherein the thermosensitive recording layers provided on both surfaces of the transparent support are thermosensitive recording layers that develop different colors.