JPH09150581A - Thermosensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve transparency and recording properties by forming a thermosensitive recording layer out of a film of a coloring agent and basic dye by an evaporation method and by making a protective layer contain acetoacetylated polyvinyl alcohol and colloidal silica. SOLUTION: An evaporation film may be formed of separate films of basic dye and a coloring agent or of a mixture film thereof. As for the basic dye, the dye coloring in blue, green, red or black, the dye having an absorption wavelength in a near-infrared region, etc., can be mentioned. As for the coloring agent, a compound having an arylsulfonylaminocarbonylamino group, or others, can be mentioned. A protective layer is formed by using acetoacetylated polyvinyl alcohol and colloidal silica. As to the acetoacetylated polyvinyl alcohol, it is preferable that the degree of acetoacetylation is 0.5-10mol% and the degree of polymerization 500-3000. The colloidal silica is a colloidal solution prepared by dispersing ultrafine particles of silicic acid anhydride in water and it is preferable that the particle size is 1-100nm, the specific gravity 1.01-1.50 and the pH value 1.5-7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material utilizing a color-developing reaction between a colorless or light-colored basic dye and a color-developing agent, which is particularly excellent in transparency and can be easily recorded with a thermal head. The present invention relates to a thermosensitive recording medium.

[0002]

2. Description of the Related Art A thermosensitive recording medium which uses a color reaction between a colorless or light-colored basic dye and an organic or inorganic colorant to contact both coloring materials by heat to obtain a recorded image is often used. Are known. Since such a thermosensitive recording medium is relatively inexpensive, the recording device is compact, and its maintenance is easy, it is used not only as a recording medium for facsimiles and various computers but also in a wide range of fields.

With the expansion of applications, not only paper but also many films and synthetic papers are prepared as the support.
One of them is a highly transparent heat-sensitive recording film having a transparent film as a support for medical use, OHP use, or drafting use. In order to increase the transparency of the heat-sensitive recording film, there is a method of atomizing the particulate material added to the recording layer or the protective layer, or increasing the proportion of the adhesive, but the transparency is not sufficient. The current situation is that there are none.

Further, Japanese Patent Application Laid-Open No. 59-106992 describes a technique for laminating a color former layer and a color former layer by vacuum vapor deposition, but the transparency and the recording property with a thermal head are not sufficient. . In order to protect the surface of the heat-sensitive layer having good transparency, the transparency is good and the sticking to the thermal head is improved.
JP-A-2-153781 describes the formulation of a protective layer, but the transparency and the recording property with a thermal head are not sufficient.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording material which is excellent in transparency and recordability in a thermal head.

[0006]

The present invention is a thermosensitive recording medium comprising a transparent support and a thermosensitive recording layer and a protective layer formed on the transparent support in that order, the thermosensitive recording layer being a film of a color former and a basic dye formed by vapor deposition. Formed by containing acetoacetylated polyvinyl alcohol and colloidal silica in the protective layer,
The inventors have found that the above problems can be solved and completed the present invention.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a vapor deposition method used in the present invention, vacuum vapor deposition by resistance heating, dielectric heating, electron beam heating, etc., sputtering vapor deposition, ion plating and the like can be adopted. As the vapor-deposited film, the film of the basic dye and the film of the color-developing agent may be separately formed, and the vapor-deposition may be performed first. Alternatively, the basic dye and the coloring agent may be deposited from different deposition sources to form a mixed film of the basic dye and the coloring agent.

As the colorless or light-colored basic dye used in the present invention, various known dyes can be used, and specific examples thereof include 3,3-bis (p-
Dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl)
Blue-coloring dyes such as -3- (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3-diethylamino-7-dibenzylamino-benzo [a] fluorane: 3
-(N-Ethyl-N-p-tolyl) amino-7-N-methylanilinofluorane, 3-diethylamino-7-anilinofluorane, 3-diethylamino-7-dibenzylaminofluorane, etc. Dyes: 3,6-bis (diethylamino) fluorane-γ-anilinolactam, 3-cyclohexylamino-6-chlorofluorane, 3-dibutylamino-6-methyl-7-bromofluorane, 3-diethylamino-7 -Methylfluorane,
3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-chlorofluorane, rhodamine (o-chloroanilino) lactam, rhodamine (p-chloroanilino) lactam, 3-diethylamino-7,8-benzofluor Oran, 3- (N-ethyl-p-
Toluidino) -7-methylfluorane, 3-diethylamino-6,8-dimethylfluorane, 3- (N-ethyl-N-isoamyl) amino-benzo [a] fluorane,
3,3'-bis (1-n-butyl-2-methylindol-3-yl) phthalide, 2- (4-dodecyloxy-
3-Methoxystyryl) quinoline and other red-coloring dyes: 3
-(N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluorane, 3-diethylamino -6-Methyl-7-anilinofluorane, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 3-di (n-pentyl)
Amino-6-methyl-7-anilinofluorane, 3-diethylamino-7- (o-chlorophenylamino) fluorane, 3-di (n-butyl) amino-7- (o-chlorophenylamino) fluorane, 3-diethylamino −
7- (o-fluorophenylamino) fluoran, 3-
Di (n-butyl) amino-7- (o-fluorophenylamino) fluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane, 3- (N
-Ethyl-p-toluidino) -6-methyl-7- (p-
Toluidino) fluorane, 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7-
Anilinofluoran, 3- (N-methyl-NNn-propylamino) -6-methyl-7-anilinofluoran,
3-Dimethylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-m-toluidinofluorane, 3- (Nn-hexyl-N-ethyl) amino- 6-methyl-7-anilinofluorane, 3
-(N-ethyl-N-isobutyl) amino-6-methyl-7-anilinofluoran, 3-diethylamino-6
Methyl-7-p-ethoxyanilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-
Piperidino-6-methyl-7-anilinofluorane,
2,2-bis {4- [6 '-(N-cyclohexyl-N
-Methylamino) -3'-methylspiro [phthalide-
3,9'-xanthene-2'-ylamino] phenyl}
Black coloring dyes such as propane and 3-diethylamino-7- (3'-trifluoromethylphenyl) aminofluorane: 3,3-bis [1- (4-methoxyphenyl) -1
-(4-dimethylaminophenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, 3,3
-Bis [1- (4-methoxyphenyl) -1- (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,
6,7-tetrachlorophthalide, 3,3-bis [1,1
-Bis (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrabromophthalide, 3-p
-(P-dimethylaminoanilino) anilino-6-methyl-7-chlorofluoran, 3-p- (p-chloroanilino) anilino-6-methyl-7-chlorofluoran,
2,4-Dimethyl-6 '-{[4- (N, N-dimethylamino) phenyl] amino} -spiro [isobenzofuran-1 (3H), 9'-[9H] xanthen] -3-one, 3 , 6-bis (dimethylamino) fluorene-9-
Examples thereof include dyes having an absorption wavelength in the near infrared region such as spiro-3 ′-(6′-dimethylamino) phthalide. Of course, it is not limited to these, and two or more kinds may be used in combination as required.

Coloring agents used in combination with the above basic dyes include, for example, 4,4'-isopropylidenediphenol and 1,1-bis (4-hydroxyphenyl).
Cyclohexane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 4,4'-dihydroxydiphenyl sulfide, hydroquinone monobenzyl ether, benzyl 4-hydroxybenzoate, 4,4'-dihydroxydiphenyl sulfone, 2 , 4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'-
Methyldiphenylsulfone, 4-hydroxyphenyl-
4'-benzyloxyphenyl sulfone, 3,4-dihydroxyphenyl-4'-methylphenyl sulfone, bis (4-hydroxyphenylthioethoxy) methane,
1,5-di (4-hydroxyphenylthio) -3-oxapentane, butyl bis (p-hydroxyphenyl) acetate, methyl bis (p-hydroxyphenyl) acetate, 1,
1-bis (4-hydroxyphenyl) -1-phenylethane, 1,4-bis [α-methyl-α- (4′-hydroxyphenyl) ethyl] benzene, 1,3-bis [α-
Methyl-α- (4′-hydroxyphenyl) ethyl] benzene, di (4-hydroxy-3-methylphenyl) sulfide, 2,2′-thiobis (3-tert-octylphenol), 2,2′-thiobis (4 -Tert-
Octylphenol) and other phenolic compounds: N,
Thiourea compounds such as N'-di-m-chlorophenylthiourea: p-chlorobenzoic acid, 4- [2- (p-methoxyphenoxy) ethyloxy] salicylic acid, 4- [3-
Aromatic carboxylic acids such as (p-tolylsulfonyl) propyloxy] salicylic acid and 5- [p- (2-p-methoxyphenoxyethoxy) cumyl] salicylic acid, and zinc, magnesium, aluminum and calcium of these aromatic carboxylic acids. A salt with a polyvalent metal such as titanium, manganese, tin, nickel, an antipyrine complex of zinc thiocyanate, a complex zinc salt of terephthalaldehyde acid and another aromatic carboxylic acid, etc .: represented by the following general formula (1): And a compound having an arylsulfonylaminocarbonylamino group.

[0010]

Embedded image

(However, R₁Is an unsubstituted or lower
Alkyl group, lower alkoxy group and halogen atom
Represents an aromatic group substituted by at least one member selected from
You. ) The compound represented by the general formula (1) is, for example, (1)
One arylsulfonylaminocarbonylamino group
As having N- (p-toluenesulfonyl) -N
^'-Phenylurea, N- (p-toluenesulfonyl)-
N^'-(P-methoxyphenyl) urea, N- (p-tolu
Ensulfonyl) -N^'-(O-tolyl) urea, N-
(P-toluenesulfonyl) -N^'-(M-tolyl) urine
Elemental, N- (p-toluenesulfonyl) -N^'-(P-
Ryl) urea, N- (p-toluenesulfonyl) -N^'−
(Pn-butylphenyl) urea, N- (p-toluene)
Sulfonyl) -N^', N^'-Diphenylurea, N- (p
-Toluenesulfonyl) -N ^'-(O-chloropheny
) Urea, N- (p-toluenesulfonyl) -N^'−
(M-Chlorophenyl) urea, N- (p-toluenesulfur
Honil) -N^'-(2,4-dichlorophenyl) urea,
N- (p-toluenesulfonyl) -N^'-Methyl-N^'
-Phenylurea, N- (p-toluenesulfonyl) -N
^'-Benzylurea, N- (p-toluenesulfonyl)-
N^'-(1-naphthyl) urea, N- (p-toluenesulfur
Honil) -N^'-(1- (2-methylnaphthyl)) urine
Elemental, N- (benzenesulfonyl) -N^'-Phenylurine
Element, N- (p-chlorobenzenesulfonyl) -N^'−
Phenyl urea, N- (o-toluenesulfonyl) -N^'−
Phenylurea, N- (p-toluenesulfonyl) -N^'
-Methylurea, N- (p-toluenesulfonyl) -N^'
-Ethylurea, N- (p-toluenesulfonyl) -N^'
-(2-phenoxyethyl) urea, N, N^'-Screw (p
-Toluenesulfonyl) urea, N- (p-toluenesulfur)
Honil) -N^'-(O-diphenyl) urea, N- (p-
Toluenesulfonyl) -N^'-(P-Ethoxycarbonyl
Ruphenyl) urea, N- (p-toluenesulfonyl)-
N^'-Butylurea, N- (p-chlorobenzenesulfoni
Le) -N^'-Propylurea, N- (p-methoxybenze
Sulfonyl) -N^'-Phenylurea etc .: (2) 2 or more
Having the above arylsulfonylaminocarbonylamino group
Bis (p-toluenesulfonylamino)
Rubonylamino) ketone, 1,2-bis (p-toluene)
Sulfonylaminocarbonylamino) ethane, 1,1,
6,6-Tetra (p-toluenesulfonylaminocarbo)
Nylamino) heptane, 1,5-bis (p-toluene)
Rufonylaminocarbonylamino) -3-oxapenta
1,5-bis (p-toluenesulfonylaminocarb
Bonylamino) -3-thiopentane, 1,3-bis (p
-Toluenesulfonylaminocarbonylamino) -2
-Propanone, 1,5-bis (p-toluenesulfonyl)
Aminocarbonylamino) -3- (2^'-(P-Torue
Sulfonylaminocarbonylamino) ethyl) -3-
Azapentane, 1,3-bis (p-toluenesulfonyl)
Aminocarbonylaminomethyl) benzene, 1,4-bi
Su (p-toluenesulfonylaminocarbonylaminometh
Chill) benzene, 4,4^'-Bis (p-toluenesulfo
Nylaminocarbonylamino) diphenylmethane, 4,
4^'-Bis (o-toluenesulfonylaminocarbonyl)
Amino) diphenylmethane, 4,4^'-Bis (benzene
Sulfonylaminocarbonylamino) diphenylmeta
4,4^'-Bis (1-naphthalenesulfonylamyl
Carbonylamino) diphenylmethane, 2,2-bis
(4^', 4^''-(P-toluenesulfonylaminocarbo
Nylamino) phenyl) propane, 1,2-bis (4^'
-(P-toluenesulfonylaminocarbonylamino)
Phenyloxy) ethane, 2,5-bis (p-toluene)
Sulfonylaminocarbonylaminomethyl) furan,
1,3-bis (p-toluenesulfonylaminocarbonione
Lumino) benzene, 1,4-bis (p-toluenesulfur)
Honylaminocarbonylamino) benzene, 1,5-bi
Su (p-toluenesulfonylaminocarbonylamino)
Naphthalene, 1,8-bis (p-toluenesulfonyl chloride
Minocarbonylamino) naphthalene, 4,4^'-Bis
(P-toluenesulfonylaminocarbonylamino) di
Phenyl ether, 3,3^'-Bis (p-toluene sulphate
Phenylaminocarbonylamino) diphenyl sulfone,
2,4-bis (p-toluenesulfonylaminocarbonyl)
Ruamino) toluene, 2,6-bis (p-toluenesulfur)
Phenylaminocarbonylamino) toluene, 4,4^'−
Bis (p-toluenesulfonylaminocarbonylamido)
No) diphenyl sulfide, and 3,4^'-Screw (p
-Toluenesulfonylaminocarbonylamino) diphe
Nyl ether and the like can be mentioned.

These arylsulfonylaminocarbonylamino compounds may be used alone or in combination of two or more. In addition, by adding a sensitizer, a storability improver, an ultraviolet absorber, etc., which are exemplified below, in a film of a color former and / or a basic dye or a mixed film of a color former and a basic dye. It is also possible to improve the color density and improve the storability of the recording portion.

Further, a sensitizer, a storability improver, an ultraviolet absorber and the like exemplified below are formed as separate films, and vapor-deposited between the upper and lower layers of the heat-sensitive recording layer or between the colorant film and the basic dye film. It can also be provided by the law. Specific examples of the sensitizer include, for example, stearic acid amide, methoxycarbonyl-
N-stearic acid benzamide, N-benzoylstearic acid amide, N-eicosanoic acid amide, ethylenebisstearic acid amide, behenic acid amide, methylenebisstearic acid amide, N-methylolstearic acid amide, dibenzyl terephthalate, dimethyl terephthalate,
Dioctyl terephthalate, benzyl p-benzyloxybenzoate, phenyl 1-hydroxy-2-naphthoate,
2-naphthylbenzyl ether, m-terphenyl, dibenzyl oxalate, oxalate-di-p-methylbenzyl, oxalate-di-p-chlorobenzyl, p-benzylbiphenyl, p-tolylbiphenyl ether, di (p-
Methoxyphenoxyethyl) ether, 1,2-di (3
-Methylphenoxy) ethane, 1,2-di (4-methylphenoxy) ethane, 1,2-di (4-methoxyphenoxy) ethane, 1,2-di (4-chlorophenoxy) ethane, 1,2-di Phenoxyethane, 1- (4-methoxyphenoxy) -2- (3-methylphenoxy) ethane, p-methylthiophenylbenzyl ether, 1,4
-Di (phenylthio) butane, p-acetotoluidide,
p-acetophenetizide, N-acetoacetyl-p-toluidine, di (β-biphenylethoxy) benzene, p
-Di (vinyloxyethoxy) benzene, 1-isopropylphenyl-2-phenylethane and the like can be mentioned.

As the preservability improver, for example, 2,2'-
Methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-
tert-butylphenol), 2,2′-ethylidenebis (4,6-di-tert-butylphenol),
4,4'-thiobis (2-methyl-6-tert-butylphenol), 4,4'-butylidenebis (6-te
rt-butyl-m-cresol), 1- [α-methyl-
α- (4′-hydroxyphenyl) ethyl] -4-
[Α ', α'-bis (4 "-hydroxyphenyl) ethyl] benzene, 1,1,3-tris (2-methyl-4-)
(Hydroxy-5-cyclohexylphenyl) butane,
1,1,3-tris (2-methyl-4-hydroxy-5
-Tert-butylphenyl) butane, 4,4'-thiobis (3-methylphenol), 4,4'-dihydroxy-3,3 ', 5,5'-tetrabromodiphenylsulfone, 4,4'-dihydroxy- 3,3 ', 5,5'-
Tetramethyldiphenyl sulfone, 2,2-bis (4-
(Hydroxy-3,5-dibromophenyl) propane,
2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,2-bis (4-hydroxy-3,
Hindered phenol compounds such as 5-dimethylphenyl) propane, 1,4-diglycidyloxybenzene,
4,4'-diglycidyloxydiphenyl sulfone, 4
-Benzyloxy-4 '-(2-methylglycidyloxy) diphenylsulfone, diglycidyl terephthalate,
Epoxy compounds such as cresol novolak type epoxy resin, phenol novolak type epoxy resin, bisphenol A type epoxy resin, N, N'-di-2-naphthyl-
Examples thereof include p-phenylenediamine, sodium or polyvalent metal salt of 2,2′-methylenebis (4,6-di-tert-butylphenyl) phosphate, and bis (4-ethyleneiminocarbonylaminophenyl) methane. Of course, it is not limited to these, and it is also possible to use two or more kinds together if necessary.

Examples of the ultraviolet absorber include salicylic acid type ultraviolet ray absorbers such as phenyl salicylate, p-tert-butylphenyl salicylate and p-octylphenyl salicylate: 2,4-dihydroxybenzophenone.
2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 2,2
^'- benzophenone ultraviolet absorbers such as dihydroxy-4-methoxybenzophenone: 2- ^(2' - hydroxy-5 ^'- methylphenyl) benzotriazole, 2-
(2 ^'- hydroxy ^-3', 5 ^'- di -tert- butylphenyl) -5-chloro-benzotriazole, 2,2
- methylenebis [4- (1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl) phenol], 2- (2 ^'- hydroxy ^-5' -t
ert-butylphenyl) benzotriazole, 2-
(2 ^'- hydroxy ^{-3'-tert-butyl-5 '-}
Methylphenyl) -5-chlorobenzotriazole, 2
- [2 ^'- hydroxy ^-3' - (3 ^'', 4 ^'', 5 ^" ', 6
^'' - tetrahydrophthalimide-methyl) -5 ^'- methylphenyl] benzotriazole, 2- ^(2' - ^{hydroxy-5'-tert-octylphenyl)} benzotriazole, 2- (2 ^'- hydroxy ^-3', 5 ^'- J-t
ert-Butylphenyl) benzotriazole, 2-4
-Di-tert-butylphenyl-3,5-di-ter
t-butyl-4-hydroxybenzoate, 2- [2 ^′
-Hydroxy-3 ^' , ^5' -bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2-
(2 ^'- hydroxy ^{-3'-tert-butyl-5 '-}
Methylphenyl) -5-chlorobenzotriazole, 2
- (2 ^'- hydroxy ^-3' - ^{dodecyl-5 '-} methylphenyl) benzotriazole, 2- ^[2' - hydroxy-4 ^{'- (2''-} ethylhexyl) oxyphenyl]
Benzotriazole, 5-tert-butyl-3- (5
-Chloro-2H-benzotriazol-2-yl) -4
-Hydroxybenzene-octyl propionate, methyl-3- [3-tert-butyl-5- (2H-benzotriazol-2-yl) -4-hydroxyphenol] propionate-polyethylene glycol (molecular weight about 30
0) and a condensate of 2- (2 ^'- hydroxy ^-3', 5 ^'
-Sec- amyl phenyl) benzotriazole of benzotriazole ultraviolet absorbers: 2-ethylhexyl-2-cyano-3,3 ^'- diphenyl acrylate, ^{ethyl-2-cyano-3,3'} - cyanoacrylates such diphenylacrylate Examples include ultraviolet absorbers. Among them, a benzotriazole-based ultraviolet absorber having strong absorption even in a relatively long wavelength ultraviolet region is preferably used. Of course, it is not limited to these, and it is also possible to use two or more kinds together if necessary.

The protective layer provided on the heat-sensitive recording material of the present invention is for protecting the surface of the heat-sensitive recording layer having good transparency as described above.
A protective layer having good transparency and capable of improving sticking to a thermal head is preferable. Such a protective layer can be mainly composed of acetoacetylated polyvinyl alcohol and colloidal silica. The degree of acetoacetylation of the acetoacetylated polyvinyl alcohol used in the present invention is appropriately selected according to the quality of the intended heat-sensitive recording material, and is generally 0.1 to 20 mol%, preferably 0. The range of 5-10 mol% is desirable.

The degree of polymerization of acetoacetylated polyvinyl alcohol is determined by the composition of the protective layer used, but is generally 300 to 4000, preferably 500 to 3.
A range of 000 is desirable. The acetoacetylated polyvinyl alcohol-based resin is generally produced by adding and reacting a liquid or gaseous diketene to a solution, dispersion or powder of the polyvinyl alcohol-based resin, but the production method thereof is not particularly limited. However, if the degree of acetoacetylation of the obtained resin is within the above range, all of them can be used. As the polyvinyl alcohol-based resin, polyvinyl alcohol and its derivatives obtained by saponifying a lower alcohol solution of polyvinyl acetate with a saponification catalyst such as alkali, and further, a monomer having a copolymerizability with vinyl acetate, It also includes a saponified product of a copolymer with vinyl acetate. Examples of the monomer copolymerizable with vinyl acetate include (anhydrous) maleic acid, fumaric acid, crotonic acid, itaconic acid, (meth) acrylic acid and other unsaturated carboxylic acids and esters thereof,
Α-olefins such as ethylene and propylene, (meth)
Olefin sulfonic acids such as allyl sulfonic acid, ethylene sulfonic acid and sulfonic acid malate, sodium (meth) allyl sulfonic acid, sodium ethylene sulfonic acid, sodium sulfonic acid (meth) acrylate, sodium sulfonic acid (monoalkyl maleate), disulfonic acid Olefin sulfonic acid alkali salt such as soda alkyl malate, amide group-containing monomer such as N-methylol acrylamide, acrylamido alkyl sulfonic acid alkali salt, and N
-Vinylpyrrolidone, N-vinylpyrrolidone derivatives and the like can be mentioned.

The colloidal silica used in the present invention is used as a colloidal solution in which ultrafine particles of silicic acid anhydride are dispersed in water using water as a dispersion medium. The particle size of colloidal silica is 1 to 100 nm, and the specific gravity is 1.01 to 1.50.
Are preferred. In this case, the colloidal solution having a pH value of 1.5 to 7 is preferably used. When the pH value approaches the alkaline side, the transparency of the protective layer tends to decrease due to the interaction with the acetoacetylated polyvinyl alcohol used.

A suitable blending ratio of acetoacetylated polyvinyl alcohol and colloidal silica in the present invention is 0.5 to 4 parts by weight, more preferably 1 to 3 parts by weight, of colloidal silica to 1 part by weight of acetoacetylated polyvinyl alcohol. It is a department. When the amount of colloidal silica used is less than 0.5 part by weight, the effect of improving transparency is small, and when it is used in excess of 4 parts by weight, the protective layer film is cracked and the transparency is rather lowered. The polyvinyl alcohol-based resin as described above has excellent curability even when used as a resin component alone. However, when a curing agent is added, a sufficiently cured resin layer can be obtained. Is one. As such a curing agent, a compound that crosslinks with a hydrophilic group in the resin component and accelerates the water resistance reaction, for example, formalin, glyoxal, glycine, glycidyl ester, glycidyl ether, dimethylol urea, ketene dimer, dialdehyde starch, melamine resin, Polyamide resin, polyamide-epichlorohydrin resin, ketone-aldehyde resin, polyethyleneimine resin, boric acid, borax, ammonium chloride, magnesium chloride, calcium chloride, aluminum sulfate, magnesium sulfate, calcium hydroxide, ammonium zirconium carbonate, Ti, Zr, Al And the like.

The amount of the curing agent used is the quality of the desired thermal recording material, the composition of the resin component and the curing agent used,
Furthermore, the pot life of the resin coating liquid and the like are taken into consideration and appropriately adjusted.
It is desirable to add it in the range of 001 to 100 parts by weight, preferably 0.1 to 30 parts by weight. In the resin coating liquid containing the specific polyvinyl alcohol resin and colloidal silica in the present invention, a pigment may be added as necessary to the extent that transparency is not impaired for the purpose of improving sticking and the like. Examples of such pigments include calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide, silicon dioxide, aluminum hydroxide, barium sulfate,
Inorganic pigments such as zinc sulfate, talc, kaolin, clay, calcined clay, magnesium salt, styrene microballs,
Examples thereof include nylon powder, polyethylene powder, urea / formalin resin filler, and organic pigments such as raw starch.

Further, in the resin coating solution, for example, waxes such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax, lauryl phosphate ester, oleyl phosphate ester, stearyl, etc. Alkyl phosphates such as phosphates and alkali metal salts thereof, glyceryl monomyristate, glyceryl monostearate, glyceryl monooleate, glyceryl distearate, glyceryl fatty acid esters such as glyceryl dioleate, diglyceryl monolaurate, dilauryl Acid polyglycerin fatty acid ester such as diglyceryl acid, tetraglyceryl monolaurate, hexaglyceryl monolaurate, and decaglyceryl monolaurate,
Lubricants such as silicone oil, wetting agents, dispersants, defoamers,
Auxiliary agents such as coloring dyes, fluorescent dyes, and ultraviolet absorbers can be added.

Further, the following water-based resins can be used to the extent that transparency and good recording property with the thermal head are not impaired. For example, starches such as oxidized starch, enzyme-modified starch, cation-modified starch, esterified starch and etherified starch: methyl cellulose, ethyl cellulose,
Polyvinyl alcohols such as carboxymethyl cellulose, methoxy cellulose, hydroxyethyl cellulose, fully (or partially) saponified polyvinyl alcohol, carboxy modified polyvinyl alcohol, silicon modified polyvinyl alcohol, polyacrylamide, polyvinyl pyrrolidone, acrylic acid amide / acrylic acid ester copolymer , Acrylic acid amide / acrylic acid ester / methacrylic acid copolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, water-soluble polymer such as casein: polyvinyl acetate, polyurethane , Polyacrylic acid, polyacrylic acid ester, polybutylmethacrylate, styrene / butadiene copolymer, vinyl chloride / vinyl acetate copolymer, ethylene / vinyl acetate copolymer Latexes such as styrene-butadiene-acrylic copolymers.

The amount of the aqueous resin used in the protective layer is preferably adjusted in the range of 20 to 80% by weight based on the total solid amount of the protective layer. In the present invention, the coating liquid for the protective layer is
Generally prepared as an aqueous coating liquid, and if necessary mixed with a mixer, attritor, ball mill, roll mill, etc.
After being sufficiently mixed and dispersed by stirring, it is coated on the heat-sensitive recording layer using a known coating device.

The coating amount of the coating liquid for the protective layer is not particularly limited, but if it is 0.1 g / m ² or less, the desired effect of the present invention cannot be sufficiently obtained, and 20 g / m ² m ²
In the above case, the recording sensitivity of the thermal recording material may be remarkably reduced, so that the dry weight is generally 0.1 to 20 g /
It is desirable that the amount is adjusted to m ² , preferably 0.5 to 10 g / m ² .

The support has a thickness of 10 to 200.
A transparent plastic film of μm, preferably 20 to 150 μm is appropriately selected for use. Examples of the transparent support include polyester films such as polyethylene terephthalate and polybutylene terephthalate, cellulose derivative films such as cellulose triacetate film, polystyrene films, polypropylene films, polyolefin films such as polyethylene, and the like. It can be pasted and used.

If desired, a resin layer may be provided on the protective layer and / or on the back surface of the heat-sensitive recording sheet to further improve the storability of the heat-sensitive recorded image. In addition, various known techniques in the field of producing a thermal recording medium can be applied by subjecting the back surface to an adhesive label to process it into an adhesive label or providing a magnetic layer. Of course, it is also possible to improve the image quality and the image density by performing a super calendering treatment after forming the thermal recording layer and the protective layer.

By coating a coating material containing a resin which is cured by electron beam irradiation on the protective layer and curing it, the glossiness can be further increased, and the color density and resistance can be further improved. It is possible to improve the print storability such as plasticizer property and water resistance. Examples of the electron beam curing resin include (A) radical-polymerizable monofunctional monomer: acrylic acid, ethyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-
Hydroxypropyl acrylate, tetrahydrofurfuryl acrylate, phenoxyethyl acrylate, triloxyethyl acrylate, nonylphenoxyethyl acrylate, tetrahydrofurfuryloxyethyl acrylate, 1,3-dioxolane acrylate, phenoxydiethylene glycol acrylate, benzyl acrylate, butoxyethyl acrylate, Cyclohexyl acrylate, dicyclopentanyl acrylate,
Dicyclopentenyl acrylate, glycidyl acrylate, carbitol acrylate, isobornyl acrylate, etc. (B) Radical polymerizable polyfunctional monomer: 1,
6-hexanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, tripropylene glycol diacrylate,
Dicyclopentanyl diacrylate, butylene glycol diacrylate, pentaerythritol diacrylate, trimethylolpropane triacrylate, propylene oxide modified trimethylolpropane triacrylate, pentaerythritol triacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol hexaacrylate, caprolactone Modified dipentaerythritol hexaacrylate, tetramethylolmethane tetraacrylate, etc. (C) Radical polymerizable oligomer (prepolymer): polyester (poly) acrylate, urethane (poly) acrylate, epoxy (poly) acrylate, polyol (poly) acrylate and the like.

The coating amount of the resin which is cured by the electron beam is not necessarily limited, but is 0.1 g.
If it is less than / m ² , the desired effect of the present invention cannot be expected,
If the coating amount exceeds g / m ² , the recording density may be significantly reduced.
m ^2, more preferably it is desirable to adjust the range of about 0.5 to 10 g / m ^2.

In addition to the above-mentioned prepolymers and monomers, if necessary, for example, pigments, defoaming agents, leveling agents, lubricants, surfactants, plasticizers, etc. are added to the electron beam curable resin component. Agents can be added as appropriate.

[0030]

The present invention will be described in more detail with reference to the following Examples, but it should be understood that the present invention is by no means restricted to such specific Examples. Parts and% in Examples are parts by weight and% by weight, respectively, unless otherwise specified. Example 1 Preparation of coating liquid for protective layer Acetoacetylated polyvinyl alcohol (trade name: Z-
210, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., 30 parts of 11% aqueous solution, 30 parts of solid concentration of 20% colloidal silica (trade name: Snowtex O, pH: 2 to 4, manufactured by Nissan Chemical Co., Ltd.), 10% of sodium dioctylsulfosuccinate. 1 part aqueous solution, 3 solids
A composition comprising 1 part of a 6% zinc stearate dispersion liquid and 1 part of a 5% aqueous glyoxal solution was mixed and stirred to obtain a coating liquid for protective layer. Formation of thermal recording layer polyester film (trade name: A-1300, manufactured by Toyobo Co., thickness 100 [mu] m) on, color acceptor N-(p-toluenesulfonyl) -N ^'- phenyl urea (melting point 165
C) in vacuum to form a colorant film having a thickness of 800 nm on the polyester film.

Then, the basic dye 3-di (n-butyl)
Amino-6-methyl-7-anilinofluoran (melting point 1
80 ° C.) was vacuum-deposited to form a film of the basic dye having a film thickness of 400 nm on the film of the color developing agent. Formation of Protective Layer After coating and drying the above coating solution for protective layer on the above basic dye film so that the coating amount after drying is 2 g / m ² ,
A thermosensitive recording medium was obtained. Example 2 Similar to Example 1 except that acetoacetylated polyvinyl alcohol (trade name: Z-200, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was used in place of acetoacetylated polyvinyl alcohol Z-210. A thermosensitive recording medium was obtained. Example 3 Similar to Example 1 except that acetoacetylated polyvinyl alcohol (trade name: OKS-6088, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was used instead of acetoacetylated polyvinyl alcohol Z-210. A thermosensitive recording medium was obtained. Example 4 In Example 1, 3-di (n-butyl) amino-6-
Methyl-7-anilinofluorane (melting point 180 ° C) 10
A mixture of 0 parts by weight and 30 parts by weight of an antioxidant 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane (melting point 201 ° C.) was vacuum-deposited to a film thickness of 400 nm. A thermosensitive recording medium was obtained in the same manner as in Example 1 except that a mixed film of a basic dye and an antioxidant was formed. Example 5 In Example 1, 3-di (n-butyl) amino-6-
Instead of methyl-7-anilinofluorane (melting point 180 ° C.), 3- (N-ethyl-N-isoamylamino)-
6-methyl-7-anilinofluorane (melting point 165 ° C)
Using, N-(p-toluenesulfonyl) -N ^'- instead of phenylurea (melting point 165 ℃), N-p- tolylsulfonyl ^-N' - except using tolyl urea (melting point 171 ° C.), the A thermal recording material was obtained in the same manner as in Example 1. Example 6 In Example 1, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane (melting point 201 was formed between the color former film and the basic dye film).
C.) was vacuum-deposited to form a 100 nm-thickness antioxidant film, thereby obtaining a thermosensitive recording medium in the same manner as in Example 1. Example 7 In Example 1, after coating the electron beam curable coating material shown below on the protective layer so that the coating amount after curing was 1.3 g / m ² , an electron beam of 4 Mrad was applied. Irradiation gave a thermosensitive recording medium having a second protective layer. Electron beam curable coating material: Polyester polyacrylate prepolymer (trade name: M-8030, manufactured by Toagosei Kagaku Co.) Example 8 In Example 1, the basic dye 3-di (n-butyl) amino-6-methyl- 7-anilinofluorane (melting point 18
0 ° C.) and a colorant N- (p-toluenesulfonyl) -N ^′
Heat treatment was carried out in the same manner as in Example 1 except that phenylurea (melting point 165 ° C.) was vacuum-deposited from different vapor deposition sources to form a mixed film of a basic dye and a colorant having a film thickness of 1000 nm on the film. I got a record. Example 9 In Example 1, colloidal silica (trade name: Snowtex O) in the composition of the coating liquid for protective layer was added at a solid concentration of 20.
% Colloidal silica (trade name: Snowtex 20,
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the pH was changed to 9.5 to 10, manufactured by Nissan Kagaku. Comparative Example 1 In Example 1, acetoacetylated polyvinyl alcohol (trade name: Z-210, in the composition of the coating liquid for protective layer).
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that silica-modified polyvinyl alcohol (trade name: R-2105, manufactured by Kuraray Co., Ltd.) was used instead of Nihon Gosei Chemical Co., Ltd.). Comparative Example 2 In Example 1, acetoacetylated polyvinyl alcohol (trade name: Z-210, in the composition of the coating liquid for protective layer).
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that carboxymethylcellulose (trade name: Serogen 5A, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used instead of Nippon Synthetic Chemical Industry Co., Ltd. Comparative Example 3 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that colloidal silica in the composition of the coating liquid for protective layer was not used. Comparative Example 4 In Example 1, acetoacetylated polyvinyl alcohol (trade name: Z-210, in the composition of the coating liquid for protective layer).
Polyvinyl alcohol (product name: manufactured by Nippon Synthetic Chemical Industry)
A thermal recording material was obtained in the same manner as in Example 1 except that the PVA-105, manufactured by Kuraray Co., Ltd. was used.

The 13 types of thermal recording materials thus obtained were subjected to the following evaluation tests, and the results are shown in [Table 1]. [Evaluation] [Recording density] Thermal printer [Product name: SCTP-6
5, Mitsubishi Electric Co., Ltd.], and the density of the obtained recorded image was measured with a Macbeth densitometer [trade name: RD-914 type, Macbeth Co.]. [Transparency of heat-sensitive recording material: haze value] The haze value of the heat-sensitive recording material was measured using a haze meter [trade name: TC-H1V, manufactured by Tokyo Denshoku Co., Ltd.]. [Evaluation of Sticking Property of Thermal Recording Material During Printing] The sticking property was evaluated when the above thermal recording material was colored with the above thermal printer.

◯: No sticking sound is generated and there is no obstacle on the coloring surface. Δ: Some sticking sound is generated, and a part of the coloring surface is damaged. X: The sticking sound is large and the coloring surface is significantly damaged.

[0034]

[Table 1]

[0035]

As is clear from the results of [Table 1], the heat-sensitive recording layer is formed of a film of a colorant and a basic dye by a vapor deposition method, and the protective layer thereon is protected by a specific material. By forming the layer, it is possible to provide a heat-sensitive recording material having excellent transparency and recording properties with a thermal head.

Claims (2)

[Claims] 1. A heat-sensitive recording material comprising a transparent support, a heat-sensitive recording layer and a protective layer provided in this order, wherein the heat-sensitive recording layer is formed of a film of a colorant and a basic dye by a vapor deposition method, and the protective layer has an acetoacetate layer. A heat-sensitive recording material containing acetylated polyvinyl alcohol and colloidal silica. 2. The heat-sensitive recording material according to claim 1, wherein the aqueous colloidal silica dispersion has a pH of 7 or less.