JPH1178237A - Thermal recording medium - Google Patents

Abstract

(57) [Summary] (Problem corrected) PROBLEM TO BE SOLVED: To solve a problem conventionally observed in a heat-sensitive recording medium utilizing a color-forming reaction between an electron-donating color compound and an electron-accepting compound. Part of the ultraviolet (3
The underlay film having a high density (60 nm to 420 nm) and having an image formed thereon is to provide a thermosensitive recording medium for the underlay film which is useful for the work of checking the underlay films. SOLUTION: An electron donating color compound is provided on a transparent support,
A heat-sensitive recording medium provided with a heat-sensitive recording layer mainly containing an electron-accepting compound and a binder resin, and further provided with an overlayer mainly containing a resin having a refractive index substantially the same as the heat-sensitive recording layer, The light transmittance of the non-image area is 380 nm or more
In an underprinting thermosensitive recording medium having a light transmittance of 35% or more in the entire wavelength region of 620 nm and a light transmittance in the image portion of 10% or less in the entire wavelength region of 380 nm to 620 nm, the electron donating color compound is as follows: A heat-sensitive recording medium for an underprint, characterized by the formula (I) or the like.

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-forming reaction between an electron-donating color-forming compound and an electron-accepting compound, and more particularly to flexographic printing, gravure printing,
The present invention relates to a heat-sensitive recording medium for plate making which is useful as a plate making film (for image formation) sheet for offset printing and silk screen printing, and particularly useful as a plate making film (for image forming) sheet for screen printing for textile printing.

[0002]

2. Description of the Related Art Hitherto, heat-sensitive recording media utilizing a color-forming reaction between an electron-donating color compound (hereinafter also referred to as a color former) and an electron-accepting compound (hereinafter also referred to as a color developer) have been widely known. Have been. In recent years, applications have expanded, and there has been a demand for overhead projectors, for second original drawings of copying systems using diazo photosensitive materials, or for design drawings, and for plate making of gravure printing, offset printing and screen printing. There is also a requirement as an underprint film.
Generally, the following properties are required when used as an underlay film. (1) The light-shielding property in the ultraviolet wavelength region of the portion of the underlay film that should shield ultraviolet light, and the transmittance of the portion that should transmit light. (2) Under the influence of temperature, humidity, and light, the light-shielding property and transmittance in the ultraviolet wavelength range do not change to a problem during the required time (preservability). (3) Easiness of viewing (checking ability) when inspecting for misalignment or mistake by overlaying several underlay films. (4) dimensional accuracy. (5) Resolution. (6) Physical strength to withstand repeated use.

Further, as a transparent thermal recording medium which can be directly recorded by a thermal head, Japanese Patent Application No. 61-12 / 1986
1875 and Japanese Patent Application Laid-Open No. 1-99873. However, in order to produce these transparent thermosensitive recording media, a coating solution comprising an emulsified dispersion obtained by microencapsulating a color former and further emulsifying and dispersing a developer dissolved in an organic solvent that is hardly soluble or insoluble in water. On a transparent support, which requires a considerably complicated process, such as production, and has a problem of insufficient transparency.

[0004] Other heat-sensitive recording media having good transparency have a problem that the image stability of a color image formed by heat energy is poor. Further, when used as the underlay film for printing plate making, it is 370 nm to 450 nm.
Since the contrast between the color image portion and the non-image portion cannot be obtained in the wavelength region of nm, it cannot be used as an underlay film for photosensitive plate making using a lamp of 370 nm to 450 nm. Further, in the conventional transparent heat-sensitive recording medium, the color tone is almost black, and when an underlay film of a black image is overlapped by two or more sheets in the inspection work of the underlay film formed by an automatic tracing or the like, There is also a problem that it is difficult to determine the deviation between the traced images. This is because the colored image portion, particularly at 450 to 600 nm, which is easily recognized by the naked eye, has a strong absorption and looks black, and it is difficult to determine whether the image portions overlap or are displaced. Japanese Patent Laid-Open Publication No. HEI 8-11881 has proposed a thermal recording medium for copymaking that satisfies such a demand. However, depending on the use of the underlay film for printing plate making, the ultraviolet (3
(60 nm to 420 nm), the problem of insufficient concentration occurred.

[0005]

SUMMARY OF THE INVENTION The present invention solves the problems conventionally encountered in a thermosensitive recording medium utilizing a color-forming reaction between an electron-donating color-forming compound and an electron-accepting compound. UV (360 nm to 420 n)
m) The density of the underprinted film is high,
It is an object of the present invention to provide a thermal recording medium for a composition useful for an inspection work of the composition films.

[0006]

The object of the present invention is to provide a heat-sensitive recording layer comprising an electron-donating color-forming compound, an electron-accepting compound and a binder resin on a transparent support. A heat-sensitive recording medium having an overlayer mainly composed of a resin having a refractive index substantially the same as that of the heat-sensitive recording layer, wherein the non-image portion has a light transmittance of 380 nm to 6 nm.
35% or more in the entire wavelength range of 20 nm, and the light transmittance in the image area is 1 in the entire wavelength range of 380 nm to 620 nm.
In a thermographic recording medium for an underprint having a content of 0% or less, the electron donating color compound is represented by the following general formula (I), (II) or (III)
A thermosensitive recording medium for an underprint, characterized in that:

[0007]

Embedded image

[0008]

Embedded image

[0009]

Embedded image And (2) the electron-accepting compound contained in the heat-sensitive recording layer is an organic phosphoric acid compound represented by the following general formula (IV) or (V), and the binder resin has a hydroxyl group or a carboxyl group in the molecule. (1) The underprinting thermosensitive recording medium according to the above (1), wherein

[0010]

Embedded image

[0011]

Embedded image Is achieved. Next, the thermosensitive recording medium of the present invention will be described in detail.

The general formulas (I) and (I) used in the present invention
The electron-donating color-forming compounds (I) and (III) are colorless or light-colored dye precursors themselves, and specific examples include the following compounds.

[0013]

[Table 1-1]

[0014]

[Table 1-2]

[0015]

[Table 1-3]

In the present invention, as the color developing agent for forming the color forming agent, a phenolic compound and an organic phosphoric acid compound which are insoluble or hardly soluble in common solvents are preferable. Examples thereof include a gallic acid compound, a protocatechuic acid compound, bis (hydroxyphenyl) acetic acid and the like, and specific examples of the organic phosphoric acid compound include an alkylphosphonic acid compound and an α-hydroxyalkylphosphonic acid. Among them, the organic phosphoric acid compound is excellent in terms of background fogging and heat sensitivity.

As a particularly preferred organic phosphoric acid compound, a phosphonic acid represented by the following formula (VI) or (VII) is used.

[0018]

Embedded image (Wherein, R represents a linear alkyl group having 16 to 24 carbon atoms)

[0019]

Embedded image (Wherein, R ′ represents a linear alkyl group having 13 to 23 carbon atoms)

Specific examples of the phosphonic acid represented by the general formula (VI) include the following compounds. Hexadecylphosphonic acid, octadecylphosphonic acid, eicosylphosphonic acid, docosylphosphonic acid, tetracosylphosphonic acid and the like. Specific examples of the phosphonic acid represented by the general formula (VII) include the following compounds.
α-hydroxytetradecylphosphonic acid, α-hydroxyhexadecylphosphonic acid, α-hydroxyoctadecylphosphonic acid, α-hydroxyeicosylphosphonic acid, α-hydroxytetracosylphosphonic acid and the like.
In the present invention, the color developer is used alone or in combination of two or more. Similarly, the color former can be applied alone or in combination of two or more.

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

As a binder resin used in the heat-sensitive recording layer, when a color-forming reaction occurs between the color-forming agent and the color-developing agent due to a force such as heat energy, the color-developing protons are attacked to form a ring-opening color. A material having an environment in which the surroundings of the dye color former are proton-rich and the color former is kept stable and the color former is hardly decolorized is preferable, for example, a compound containing a hydroxyl group or a carboxylic acid group in the binder resin, Further, the refractive index at room temperature is more preferably 1.45 to 1.45.
Compounds in the range 1.60.

Examples of such a binder resin include polyvinyl butyral (1.48 to 1.49), polyvinyl acetal (1.50), and epoxy resin (1.5
5-1.61), ethylcellulose (1.46-1.4)
9), cellulose acetate (1.46-1.50),
Cellulose acetate butyrate (1.46 to 1.4)
9), cellulose acetate propionate (1.46)
-1.49), nitrocellulose (1.49-1.5)
1) and the like. Here, the numerical value in parentheses is the refractive index.

Further, the improvement of the light resistance of the heat-sensitive recording medium of the present invention can be achieved by including a light stabilizer in the heat-sensitive recording layer or the protective layer. As the light stabilizer used in the present invention, an ultraviolet absorber, an antioxidant, an antioxidant,
A quencher for singlet oxygen and a quencher for superoxide anion are used.

As the ultraviolet absorber, for example, 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 ultraviolet absorbers such as benzophenone and 2-hydroxy-4- (2-hydroxy-3-methylacryloxy) propoxybenzophenone; 2- (2 ′
-Hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-ditert-butylphenyl) benzotriazole, 2-
(2′-hydroxy-3′-tert-butyl-5 ′
-Methylphenyl) benzotriazole, 2- (2'-
(Hydroxy-4′-octoxy) benzotriazole,
2- (2'-hydroxy-3 ', 5'-ditert-butylphenyl) 5-chlorobenzotriazole, 2-
(3′-tert-butyl-2′-hydroxy-5 ′
-Methylphenyl) 5-chlorobenzotriazole, 2
Benzotriazole-based ultraviolet absorbers such as-(2'-hydroxy-5-ethoxyphenyl) benzotriazole, phenyl salicylate, p-octylphenyl salicylate, p-tert-butylphenyl salicylate, carboxylphenyl salicylate, methylphenyl salicylate, dodecylphenyl Salicylic acid phenyl ester type ultraviolet absorber such as salicylate or p-methoxybenzylidene malonic acid dimethyl ester,
2-ethylhexyl-2-cyano-3,3'-diphenyl acrylate, ethyl-2-cyano-3,3'-diphenyl acrylate, 3,5-ditert-butyl-
p-hydroxybenzoic acid, resorcinol monobenzoate which rearranges to benzophenone by ultraviolet rays, 2,
4-di-tert-butylphenyl, 3,5-di-tert-butyl-4-hydroxybenzoate and the like.

Examples of the antioxidant and antioxidant include:
2,6-di-tert-butyl-4-methylphenol, 2,4,6-tri-tert-butylphenol,
Styrenated phenol, 2,2'-methylenebis (4-
Methyl-6-tert-butylphenol), 4,
4'-isopropylidenebisphenol, 2,6-bis (2'-hydroxy-3'-tert-butyl-5 '
-Methylbenzyl) -4-methylphenol, 4,4 '
-Thiobis- (3-methyl-6-tert-butylphenol), tetrakis- {methylene (3,5-ditert-butyl-4-hydroxyhydrocinnamate)} methane, p-hydroxyphenyl-3-naphthylamine, 2,2 , 4-Trimethyl-1,2-dihydroquinoline, thiobis (β-naphthol), mercaptobenzothiazole, mercaptobenzimidazole, aldol-2-naphthylamine, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate , 2,2,
6,6-tetramethyl-4-piperidyl benzoate,
Dilauryl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, tris (4-
(Nonylphenol) phosphite.

As singlet oxygen quenchers, carotenes,
There are pigments, amines, phenols, nickel complexes, sulfides and the like, for example, 1,4-diazabicyclo (2,2,2) octane, β-carotene, 1,3-cyclohexadiene, 2-diethylamino Methylfuran,
2-phenylaminomethylfuran, 9-diethylaminomethylanthraceacene, 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′-sulfonbis (4-octylphenolate)}, nickel bis (2
-Hydroxy-5-methoxyphenyl-NN-butylaldimine), nickel bis (dithiobenzyl), nickel bis (dithiobiacetyl) and the like.

Superoxide anion quencher includes superoxide dismutase and cobalt [III]
And complexes of nickel [II] 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 at room temperature in the range of 1.45 to 1.60. For example, polyethylene terephthalate, a polyester film such as polybutylene terephthalate, a cellulose derivative film such as cellulose triacetate, a polypropylene, a polyolefin film such as polyethylene, a polystyrene film, or a transparent support obtained by laminating these are generally used. is there.

It is preferable to provide an adhesive layer between the recording layer and the heat-sensitive recording layer. As a material of the adhesive layer, generally, an acrylic resin, a saturated polyester resin, or the like, and a resin obtained by curing these are used.

In a heat-sensitive recording medium having no protective layer, the surface and inside of the heat-sensitive recording layer become uneven because a fine color developer is dispersed in a binder resin. Light scattering occurs due to the difference in refractive index between the existing air and the recording layer, and the recording layer is opaque or translucent. However, like the thermosensitive 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 thermosensitive recording layer is uniformly coated and dried (cured) on the opaque or translucent recording layer. As a result, the recording layer is smoothed without voids and irregularities, and light scattering is reduced, thereby obtaining a transparent recording medium. The protective layer formed here not only contributes to the transparency of the recording medium, but also has a great effect on improving chemical resistance, water resistance, friction resistance, light resistance and head matching,
It is indispensable as a component of a high-performance transparent thermal recording medium.

The protective layer of the present invention includes a film formed mainly of a water-soluble resin or a hydrophobic resin, a film mainly formed 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. Also, by containing an organic or inorganic filler and a lubricant, there is no problem such as sticking caused by contact with a thermal head or the like,
A heat-sensitive recording medium having excellent reliability and head matching can be obtained.

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 heat-sensitive recording layer is used. Here, the fact that the refractive indices are the same means that they are substantially the same, and includes the case where they differ by about ± 5%. The resin having a refractive index of 1.45 to 1.60 at room temperature is preferable.

Such resins include water-soluble resins, aqueous emulsions, hydrophobic resins, ultraviolet curable resins, electron beam curable resins, and the like. Specific examples of the water-soluble resin include, for example, polyvinyl alcohol, modified polyvinyl alcohol, cellulose derivatives (methylcellulose, methoxycellulose, hydroxyethylcellulose, etc.), casein, gelatin, polyvinylpyrrolidone,
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, melamine-formaldehyde resin, urea-formaldehyde resin, etc. . Examples of the resin or the hydrophobic resin for the aqueous emulsion include polyvinyl acetate, polyurethane, styrene / butadiene copolymer, styrene / butadiene / acrylic copolymer, polyacrylic acid, polyacrylate, vinyl chloride, and acetic acid. Vinyl copolymer,
Examples thereof include polybutyl methacrylate and an ethylene / vinyl acetate copolymer. 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 type of the UV-curable resin used for forming the protective layer is not limited as long as it is a monomer or oligomer (or prepolymer) which undergoes a polymerization reaction upon irradiation with ultraviolet light and cures to become a resin, and is known in the art. All can be used. Examples of such a monomer or oligomer include (poly) ester acrylate, (poly) urethane acrylate, epoxy acrylate, polybutadiene acrylate, silicone acrylate, and melamine acrylate. (Poly) ester acrylate is obtained by reacting polyhydric alcohols such as 1,6-hexanediol, propylene glycol (as propylene oxide) and diethylene glycol with polybasic acids such as adipic acid, phthalic anhydride and trimellitic acid and acrylic acid. It is a thing. Examples of the structure are shown in (a) to (c). (A) adipic acid / 1,6-hexanediol / acrylic acid

[0036]

Embedded image (B) phthalic anhydride / propylene oxide / acrylic acid

[0037]

Embedded image (C) trimet acid / diethylene glycol / acrylic acid

[0038]

Embedded image

(Poly) urethane acrylate is obtained by reacting a compound having an isocyanate group such as tolylene diisocyanate (TDI) with an acrylate having a hydroxyl group. An example of the structure is shown in FIG.
HEA is 2-hydroxyethyl acrylate, H
DO stands for 1,6-hexanediol, and ADA stands for adipic acid. (D) HEA / TDI / HDO / ADA / HDO / TD
I / HEA

[0040]

Embedded image

Epoxy acrylates are roughly classified into bisphenol A type, novolak type and alicyclic type according to their structures. These epoxy resins are obtained by esterifying the epoxy group of the epoxy resin with acrylic acid to make the functional group an acryloyl group.
Examples of the structure are shown in (e) to (g). (E) Bisphenol A-epichlorohydrin type / acrylic acid

[0042]

Embedded image (F) phenol novolak-epichlorohydrin type /
Acrylic acid

[0043]

Embedded image (G) Alicyclic type / acrylic acid

[0044]

Embedded image

Polybutadiene acrylate has a terminal OH
Isocyanate or 1,2 polybutadiene
-A product obtained by reacting with mercaptoethanol or the like, and further reacting with acrylic acid or the like. (H)
Shown in (H)

[0046]

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

[0047]

Embedded image

When using an ultraviolet curable resin, a solvent may be used. Examples of the solvent include tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, chloroform, carbon tetrachloride, ethanol, isopropyl alcohol, and the like. Organic solvents such as ethyl acetate, butyl acetate, toluene and benzene are exemplified.
Instead of these solvents, a photopolymerizable monomer can be used as a reactive diluent for easy handling.

Examples of photopolymerizable monomers include 2-ethylhexyl acrylate, cyclohexyl acrylate, butoxyethyl acrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, trimethylolpropane triacrylate, and pentaerythritol. And trit triacrylate.

Next, the electron beam curable resin will be described. The type of the electron beam-curable resin is not particularly limited, but a particularly preferable electron beam-curable resin is an electron beam-curable resin (hereinafter, referred to as “electron beam-curable resin”) having a polyester-based skeleton and having a pentafunctional or more branched molecular structure. Acrylate-modified polyurethane resin ") and a silicone-modified electron beam-curable resin.

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 polypropylene glycol and adipic acid (the above corresponds to a polyester skeleton portion, etc.) and a mixture of polyester diol and polyether triol. , A diisocyanate and a compound having an acrylic double bond are added and reacted. Instead of the mixture of the polyester diol and the polyether triol, for example, a mixture of the polyether diol and the triether triol, a mixture of the polyester diol and the polyester triol, and a mixture of the polyether diol and the polyester triol are used. Here, examples of the diisocyanate include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,6-hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, and methylene bis (4-phenyl isocyanate). Examples of the compound having an acrylic double bond include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate,
Examples thereof include 3-hydroxypropyl (meth) acrylate. The polyester diol is, for example, ADEKA NEW ACE Y4-30 (manufactured by Asahi Denka Kogyo KK), and the polyether triol is, for example, Sannics TP.
-400, Sannics GP-3000 (all manufactured by Sanyo Chemical Industries, Ltd.) and the like.

The molecular weight of the polyester portion of the electron beam-curable acrylic-modified polyurethane resin is set at 200 to provide the heat-resistant slip layer with the required flexibility and toughness.
A range from 0 to 4000 is preferred. 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 described above. In this resin, when the number of functional groups is 5 or more, preferably 7 to 13, the effects such as acceleration of curing and improvement of hardness can be obtained.

On the other hand, the silicone-modified electron beam-curable resin has the following chemical structure.

[0054]

Embedded image (Where R is-(CH ₂ ) -n (n = 0 to
3), TDI is 2,4-tolylene diisocyanate, H
EM represents 2-hydroxyethyl acrylate, and x =
50-100 y = 3-6. ) This silicone-modified electron beam-curable resin has excellent coating properties, so that a uniform and thin coating can be formed satisfactorily.
Also, since it has a silicone functional group, the sliding effect is excellent.

When the wire-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 3 parts of the electron beam-curable silicone-modified resin.
It is desirable to add up to 0 parts by weight, preferably in the range of 5 to 20 parts by weight.

In the protective layer of the present invention, in order to promote curing and improve heat resistance during the formation process,
It is desirable to use a multifunctional electron beam curable monomer in combination.
This monomer acts as a crosslinking accelerator and is advantageous in forming a complex and high-density crosslinked structure. Specific examples of such a monomer include trimethylolpropane triacrylate, tetramethylolmethanetetraacrylate, pentaerythritol triacrylate, dipentaerythritol hexatriacrylate, and the like. The monomer is preferably added in an amount of up to 50 parts by weight, preferably 20 to 50 parts by weight, per 100 parts by weight of the electron beam-curable acrylic-modified polyurethane resin. If the amount is more than 50 parts by weight, the lubricating hardening is weakened and the sliding effect is reduced.

The over layer according to the present invention is a phosphazene-based resin having a repeating unit having a phosphazene skeleton represented by the following chemical formula, and is extremely excellent in heat resistance.

Embedded image-(P = N)-Specific examples include, but are not limited to, those represented by the following chemical formulas.

-[NP (A) a (B) b] n- (where a, b; a> 0, b ≧ 0, and a + b =
A is a real number that satisfies 2, A is a polymerization curable group such as a methacryloyloxyethyl group, and B is

[0058]

Embedded image Here, R _{1 to} R ₅ each represent a hydrogen atom, a chlorine atom, a bromine atom or a halogenated alkyl group having 1 to 4 carbon atoms,
M represents an oxygen atom, a sulfur atom or an imino group. )

The phosphazene resin represented by the above chemical formula, for example, A is a methacryloyloxyethyl group and b
= 0 can be produced by ring-opening polymerization of a compound represented by the following chemical formula.

[0060]

Embedded image

When the polymer has a polymerizable group such as the Bosfanzen resin represented by the above chemical formula, the resin is cured by ultraviolet rays, an electron beam, heating, or the like to further improve the mechanical strength.
Hardness and heat resistance are improved.

In the protective layer of the present invention, similarly to the heat-sensitive recording layer,
A light stabilizer can be included for improving light fastness. As the light stabilizer used in the present invention, an ultraviolet absorber, an antioxidant, an antioxidant, a quencher of singlet oxygen,
Superoxide anion quenchers, which are the same as those used in the heat-sensitive recording layer.

Further, the improvement of the head matching property of the thermal recording medium of the present invention can be achieved by including an organic or inorganic filler and a lubricity additive in the protective layer to such an extent that the transparency is not reduced. Examples of the organic filler used in the present invention include polyolefin particles, polystyrene particles, urea-formaldehyde resin particles, or plastic fine hollow particles, and the like, and inorganic fillers include aluminum hydroxide, heavy and light calcium carbonate, Zinc oxide, titanium oxide, barium sulfate, silica gel, colloidal silica (10 to 50 μm), alumina sol (10 to
Activated clay, talc, clay titanium white, kaolinite, calcined kaolinite, diatomaceous earth,
Synthetic kaolinite, zirconium compounds, glass hollow microspheres, etc., are preferred. Particularly, fillers having a spherical shape and having lubricity such as Si resin and fluorine resin are desirable. Examples of the lubricating additive include a lubricating agent such as silicone oil, a surfactant, an organic salt and a wax, and a lubricating filler. As silicone oil,
Examples include dimethylpolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, alkyl-modified polysiloxane, amino-modified polysiloxane, carboxyl-modified polysiloxane, and alcohol-modified polysiloxane.

Examples of the surfactant include commercially available carboxylic acids, sulfates and sulfonates of higher alcohols, phosphates of higher alcohols and salts thereof. 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 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,
Sodium nonylnaphthalenesulfonate, sodium dodecylnaphthalenesulfonate, potassium dodecylnaphthalenesulfonate, sodium N-oleoyl-N-methyltaurine, tetraethoxylauryl alcoholate, sodium monostearyl phosphate, sodium distearyl phosphate However, the present invention is not limited to these.

Examples of the organic salts include metal soaps such as zinc stearate, aluminum stearate, calcium stearate, and magnesium stearate, hexyl ammonium chloride, sodium sulfosalicylate, sodium succinate, potassium succinate, and benzoic acid. And salts such as potassium and potassium adipate.

Further, natural waxes include candelilla wax, carnauba wax, rice wax, beeswax, lanolin wax, montan wax, paraffin wax, microcrystalline wax, and synthetic waxes include polyethylene wax, hardened castor oil and derivatives thereof, And fatty acid amides. The amount of the lubricant occupying in the protective layer is 0.001 to 15.
0% by weight is suitable. If it is more than this, the mechanical strength of the protective layer will be poor, and if it is less than this, the effect of the lubricant will be lost.

In the heat-sensitive recording medium for underprinting of the present invention, only the developer is uniformly dispersed in an organic solvent, and then the color former and the binder resin are uniformly mixed in order to prepare a heat-sensitive recording layer coating solution.
Either disperse the color developer uniformly in a binder resin solution obtained by dissolving the binder resin in an organic solvent and adjust the coating solution of the heat-sensitive recording layer by uniformly mixing the color former or the like, or combine the color former and the developer with the binder resin. Uniformly dispersed in an organic solvent, to prepare a heat-sensitive recording layer coating solution, or a coating solution uniformly dispersed by any method, one side of the transparent support, or coated and dried on both sides to provide a heat-sensitive recording layer, Further, it is manufactured by providing a protective layer mainly composed of a resin thereon.

Examples of the organic solvent for dissolving the binder resin include ethers such as dibutyl ether, isopropyl ether, dioxane, and tetrahydrofuran; acetone;
Ketones such as diethyl ketone, methyl ethyl ketone, methyl isobutyl ketone, methyl propyl ketone, ethyl acetate, isopropyl acetate, n-propyl acetate, and n-acetate
There are esters such as butyl and aromatic hydrocarbons such as benzene, toluene and xylene, which are used alone or in combination.

There are no particular restrictions on the coating method and coating amount of the protective layer. However, the coating amount is preferably 0.1 to 0.1 μm on the recording medium in consideration of the performance and economy of the protective layer. 20
μm range, more preferably the coating thickness is 0.5 to 10 μm
Is the range of the film thickness where 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 a hot pen, a thermal head, laser heating, thermal etching using light, and the like. However, it is practically preferable to form an image using a thermal head.

[0071]

The present invention will be described in more detail with reference to the following examples. In the following, all parts and percentages are based on weight. Example 1 The following composition was dispersed in a table-top ball mill, and the average particle size of octadecylphosphonic acid was dispersed to 0.3 μm to prepare a recording layer coating liquid. [Recording layer coating solution] Fluorane compound of formula (1) in Table 1 10 parts Octadecylphosphonic acid 30 parts Polyvinyl butyral (refractive index 1.49, Denka Butyral # 3000-2, manufactured by Denki Kagaku Kogyo Co., Ltd.) 15 parts Toluene / 285 parts of methyl ethyl ketone (1/1) mixed solution

The following solutions A and B were uniformly dispersed to about 0.5 μm, and further uniformly mixed with the solution C to prepare an overlayer coating solution. [Overlayer coating solution] Liquid A Kaolin (Ryosan Shoji Co., Ltd., UW-90) 10 parts Silicone-modified polyvinyl butyral resin (Dainichi Seika, SP-712, solid content 12.5%) 8 parts Methyl ethyl ketone 12.5 Part B liquid zinc stearate 3.3 parts silicone modified polyvinyl butyral resin (manufactured by Dainichi Seika, SP-712, solid content 12.5%) 2.6 parts methyl ethyl ketone 4.1 parts liquid C silicone modified polyvinyl butyral resin (large 80 parts urethane acrylate UV curable resin solution (refractive index: 1.56, manufactured by Dainippon Ink and Chemicals, Unidick V9057, solid content: 75%) 20 parts Silicone resin fine particles (Toshiba Silicone Co., Ltd., Tospearl 130, 3 μm) 15 parts Silicone oil (Shin-Etsu Chemical X22-161AS manufactured by Gaku Kogyo Co., Ltd. 1.5 parts Polyisocyanate compound (Coronate L manufactured by Nippon Polyurethane Industry Co., Ltd.) 11.5 parts Toluene / methyl ethyl ketone (1/1) mixed solution 200 parts

[Antistatic Layer Coating Solution] SnO ₂ -Sb / Polyester Emulsion Dispersion (Colcoat Co., Ltd., Colcoat SP-2002) 10 parts Methanol / water (1/2) mixed solution 90 parts [Preparation of thermosensitive recording medium] 75 μm Melinex 705
Apply the antistatic layer coating solution to one side of a polyester film (manufactured by ICI Japan) using a wire bar.
After drying, an antistatic layer having a thickness of about 0.3 μm was provided. On the opposite surface, a coating solution for the recording layer is applied and dried using a wire bar to provide a heat-sensitive recording layer having a thickness of about 13 μm. /3.5cm with UV lamp
A thick over layer was provided, and the thermal recording medium of Example 1 was produced.

Example 2 The following composition was dispersed in a table-top ball mill, the average particle size of octadecylphosphonic acid was dispersed to 0.3 μm, and Tospearl 145 (manufactured by Toshiba Silicone Co., Ltd., 4.5 μm in volume average particle size, oil absorption) 58 ml / 100 g) to 5.5
A part of the mixture was uniformly dispersed to prepare a recording layer coating liquid. [Recording layer coating solution] Fluorane compound of formula (14) in Table 1 10 parts Octadecylphosphonic acid 30 parts Polyvinyl butyral (refractive index 1.49, Denka Butyral # 3000-2, manufactured by Denki Kagaku Kogyo Co., Ltd.) 15 parts Toluene / 285 parts of methyl ethyl ketone (1/1) mixed solution

The following solutions A and B were uniformly dispersed to about 0.5 μm, and further uniformly mixed with the solution C to prepare an overlayer coating solution. [Overlayer coating solution] Liquid A Kaolin (UW-90, manufactured by Ryosan Shoji Co., Ltd.) 33 parts Silicone-modified polyvinyl butyral resin (manufactured by Dainichi Seika, SP-712, solid content: 12.5%) 26 parts Methyl ethyl ketone 41 parts B Liquid Zinc stearate 10 parts Silicone modified polyvinyl butyral resin (manufactured by Dainichi Seika, SP-712, solid content 12.5%) 7.8 parts Methyl ethyl ketone 12.2 parts Liquid C Silicone modified polyvinyl butyral resin (manufactured by Dainichi Seika, SP-712, solid content 12.5%) 150 parts Urethane acrylate UV curable resin solution (refractive index 1.56, manufactured by Dainippon Ink and Chemicals, Unidick V9057, solid content 75%) 135 parts Silicone resin fine particles ( Toshiba Silicone Co., Ltd., Tospearl 130, 3μm) 30 parts Silicone oil (Bit 3 parts polyisocyanate compound (Coronate HL, manufactured by Nippon Polyurethane Industry Co., Ltd.) 20 parts Toluene / methyl ethyl ketone (1/1) mixed solution 180 parts

[Antistatic Layer Coating Solution] SnO ₂ -Sb / Polyester Emulsion Dispersion (Colcoat Co., Ltd., Colcoat SP-2002) 10 parts Methanol / water (1/2) mixed solution 90 parts [Preparation of thermosensitive recording medium] 75 μm Melinex 705
Apply the antistatic layer coating solution to one side of a polyester film (manufactured by ICI Japan) using a wire bar.
After drying, an antistatic layer having a thickness of about 0.3 μm was provided. On the opposite side, a recording layer coating solution is applied and dried using a wire bar to provide a heat-sensitive recording layer having a thickness of about 14 μm. Further, an overlayer coating solution is applied and dried on the recording layer using a wire bar to 80 W. /3.5cm with UV lamp
A thermosensitive recording medium of Example 2 was produced by providing a thick overlayer.

Example 3 The following composition was dispersed in a table-top ball mill, and the average particle diameter of octadecylphosphonic acid was dispersed to 0.3 μm to prepare a recording layer coating liquid. [Recording layer coating solution] Fluorane compound of formula (15) in Table 1 10 parts Octadecylphosphonic acid 30 parts Polyvinyl butyral (refractive index: 1.49, Denka Butyral # 3000-2, manufactured by Denki Kagaku Kogyo Co., Ltd.) 15 parts Toluene / 285 parts of methyl ethyl ketone (1/1) mixed solution

The following solutions A and B were uniformly dispersed to about 0.5 μm, and further uniformly mixed with the solution C to prepare an overlayer coating solution. [Overlayer coating solution] Liquid A Urea-formalin type organic filler (manufactured by Nippon Kasei Co., Ltd.) 33 parts Silicone-modified polyvinyl butyral resin (manufactured by Dainichi Seika, SP-712, solid content 12.5%) 26 parts Methyl ethyl ketone 41 parts B Liquid Zinc stearate 3.3 parts Silicone-modified polyvinyl butyral resin (manufactured by Dainichi Seika, SP-712, solid content 12.5%) 2.6 parts Methyl ethyl ketone 4.1 parts Liquid C Silicone-modified polyvinyl butyral resin (Dainichi Seika 150 parts, urethane acrylate UV curable resin solution (refractive index 1.56, manufactured by Dainippon Ink and Chemicals, Unidick V9057, solids 75%) 135 parts Silicone resin Fine particles (Toshiko Silicone, Tospearl 130, 3μm) 30 parts Silicone Le (Toray Silicone Co., SH29PA) 1.5 parts Polyisocyanate compound (manufactured by Nippon Polyurethane Industry Co., Coronate HL) 20 parts Toluene / methyl ethyl ketone (1/1) mixture 180 parts

[Antistatic Layer Coating Solution] SnO ₂ —Sb / Polyester Emulsion Dispersion (Colcoat Co., Ltd., Colcoat SP-2002) 10 parts Methanol / water (1/2) mixed solution 90 parts [Preparation of thermosensitive recording medium] 75 μm Melinex 705
Apply the antistatic layer coating solution to one side of a polyester film (manufactured by ICI Japan) using a wire bar.
After drying, an antistatic layer having a thickness of about 0.3 μm was provided. On the opposite surface, a coating solution for the recording layer is applied and dried using a wire bar to provide a heat-sensitive recording layer having a thickness of about 13 μm. /3.5cm with UV lamp
A thermosensitive recording medium of Example 3 was produced by providing a thick overlayer.

Example 4 The following composition was dispersed in a table-top ball mill, and the average particle size of octadecylphosphonic acid was dispersed to 0.3 μm to prepare a recording layer coating solution. [Coating solution for recording layer] Fluorane compound of formula (18) in Table 1 10 parts Octadecylphosphonic acid 30 parts Polyvinyl butyral (refractive index 1.49, Denka Butyral # 3000-2, manufactured by Denki Kagaku Kogyo Co., Ltd.) 15 parts Toluene / 285 parts of methyl ethyl ketone (1/1) mixed solution

The following solutions A and B were uniformly dispersed to about 0.5 μm, and further uniformly mixed with the solution C to prepare an overlayer coating solution. [Overlayer coating solution] Liquid A Kaolin (UW-90, manufactured by Ryosan Shoji Co., Ltd.) 33 parts Silicone-modified polyvinyl butyral resin (manufactured by Dainichi Seika, SP-712, solid content: 12.5%) 26 parts Methyl ethyl ketone 41 parts B Liquid Zinc stearate 10 parts Silicone modified polyvinyl butyral resin (manufactured by Dainichi Seika, SP-712, solid content 12.5%) 7.8 parts Methyl ethyl ketone 12.2 parts Liquid C Silicone modified polyvinyl butyral resin (manufactured by Dainichi Seika, SP-712, solid content 12.5%) 150 parts Urethane acrylate UV curable resin solution (refractive index 1.56, manufactured by Dainippon Ink and Chemicals, Unidick V9057, solid content 75%) 135 parts Silicone resin fine particles ( Toshiba Silicone Co., Ltd., Tospearl 120, 2 μm, oil absorption 75 ml / 100 g) 3 Part silicone oil (manufactured by BYK Japan Co., Byk-344) 3 parts Polyisocyanate compound (manufactured by Nippon Polyurethane Industry Co., Coronate HL) 20 parts Toluene / methyl ethyl ketone (1/1) mixture 180 parts

[Coating Solution for Antistatic Layer] SnO ₂ -Sb / Polyester Emulsion Dispersion (Colcoat Co., Ltd., Colcoat SP-2002) 10 parts Methanol / water (1/2) mixed solution 90 parts [Preparation of thermosensitive recording medium] 75 μm Melinex 705
Apply the antistatic layer coating solution to one side of a polyester film (manufactured by ICI Japan) using a wire bar.
After drying, an antistatic layer having a thickness of about 0.3 μm was provided. On the opposite surface, a coating solution for the recording layer is applied and dried using a wire bar to provide a heat-sensitive recording layer having a thickness of about 13 μm. / Cm and cured with an ultraviolet lamp, and an overlayer having a thickness of about 3 μm was provided. Thus, a thermosensitive recording medium of Example 4 was produced.

Comparative Example 1 The formula (1) in Table 1 used for the recording layer coating solution of Example 1 was used.
A heat-sensitive recording medium of Comparative Example 1 was produced in the same manner as in Example 1 except that 2-anilino-3-methyl-6-diethylaminofluoran was used instead of the fluoran compound. Comparative Example 2 Formula (1) in Table 1 used for the recording layer coating solution of Example 1
A heat-sensitive recording medium of Comparative Example 2 was produced in the same manner as in Example 1, except that 2- (o-chlorophenylamino) -6-ethylamino-7-methylfluoran was used in place of the fluoran compound.

Printing Test The heat-sensitive recording medium produced as described above was added with 8 dots /
With a printing device using a thermal head having a thickness of 0.7 mm, an applied energy of 0.7 W / dot and a printing pulse width of 0.7 msec were applied to record a color image. Coloring Tone The coloring tone of the color image sample printed in the above test was visually evaluated. Transmission Density The image density and the background (non-image portion) density of the printed color image sample were measured using a transmission densitometer X-Rite 309 (X-RI
The measurement was performed in a UV mode (manufactured by TE Company). Spectral Transmittance The spectral transmittance of the colored image portion and the non-image portion of the thermosensitive recording medium was measured at a spectral wavelength of 380 nm and 440 nm using a spectrophotometer UV-3100 manufactured by Shimadzu Corporation. Table 2 shows the above results.

[0085]

[Table 2]

[0086]

As is apparent from the detailed and specific description, the thermal recording medium for an underprint of the present invention has a size of 380 to 380.
Since the difference in light transmittance between the color-developed image area and the non-image area is 35% or more in the entire wavelength range of 440 nm, the ultraviolet ray density of the image area is particularly high, and the spectral transmittance of the background area is excellent. Yes, it is a heat-sensitive recording medium particularly useful as an underlay film (for image formation) for plate making in flexographic printing, gravure printing, offset printing and silk screen printing.

Claims (2)

[Claims] 1. An electron donating color compound on a transparent support,
A heat-sensitive recording medium provided with a heat-sensitive recording layer mainly containing an electron-accepting compound and a binder resin, and further provided with an overlayer mainly containing a resin having a refractive index substantially the same as the heat-sensitive recording layer, The light transmittance of the non-image area is 380 nm or more
In an underprinting thermosensitive recording medium having a light transmittance of 35% or more in the entire wavelength region of 620 nm and a light transmittance in the image area of 10% or less in the entire wavelength region of 380 nm to 620 nm, the electron-donating color forming compound is as follows: Formulas (I), (II), (II
I) A thermal recording medium for a composition, characterized in that: Embedded image Embedded image Embedded image 2. The electron-accepting compound contained in the heat-sensitive recording layer is an organic phosphoric acid compound represented by the following general formula (IV) or (V), and the binder resin has a hydroxyl group or a carboxyl group in the molecule. The thermal recording medium for underlay composition according to claim 1, characterized in that it contains. Embedded image Embedded image