JP2002356071A - Thermal transfer sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal transfer sheet which can prevent the deterioration of an image quality, such as a change of hue in a recorded image, caused by the migration of a photothermal conversion dyestuff such as an infrared absorbing dyestuff contained in a photothermal conversion layer to an image forming layer and the decomposition of the dyestuff after laser recording and which is excellent in light-resistance and transferability. SOLUTION: The photothermal conversion layer containing at least the infrared absorbing dyestuff and the image forming layer are provided in this sequence on a substrate, and the photothermal conversion layer contains at least one kind of anionic polymer which can form a salt with the infrared absorbing dyestuff.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer sheet used in an image forming method for forming a high-resolution image by using a laser beam. The present invention relates to a thermal transfer sheet excellent in light resistance and transferability.

[0002]

2. Description of the Related Art Conventionally, as a recording material used in a transfer image forming method using a laser beam, a photothermal conversion dye such as an infrared absorbing dye or the like, which absorbs a laser beam and generates heat, is provided on a support. There is known a thermal transfer sheet in which a conversion layer and an image forming layer in which a pigment is dispersed in components such as a heat-fusible wax and a binder are provided in this order. In the image forming method using this, the heat generated in the laser light irradiation area of the light-to-heat conversion layer melts the image forming layer corresponding to the area and is transferred onto the transfer material stacked on the thermal transfer sheet. Thus, a transfer image is formed.

However, in the light-to-heat conversion layer, the light-to-heat conversion dye such as an infrared absorbing dye contained in the layer is transferred to the image forming layer when the thermal transfer sheet is stored, and when laser light irradiation is performed in that state, the image forming There is a problem that a decomposition product of the dye remains in the layer, and the image formation layer is colored by the decomposition product of the dye. further,
When light is applied to the decomposition product of the dye remaining in the image forming layer, fading occurs, and as a result, there is a problem that the hue of the recorded image fluctuates. Another problem is that transferability is deteriorated when an image is retransferred from the material to be transferred to a final material to be transferred, such as recording paper, due to the transfer of the infrared absorbing dye to the image forming layer. is there.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and achieve the following objects. That is, the present invention relates to the transfer of a light-to-heat conversion dye such as an infrared absorbing dye contained in the light-to-heat conversion layer to the image forming layer, and the image quality such as a change in hue in the recorded image due to the decomposition of the dye after laser recording. An object of the present invention is to provide a thermal transfer sheet that can prevent deterioration and is excellent in light resistance and transferability.

[0005]

Means for solving the above problems are as follows. (1) A thermal transfer sheet comprising a support and a photothermal conversion layer containing at least an infrared absorbing dye and an image forming layer provided in this order, wherein the photothermal conversion layer is an anion capable of forming a salt with the infrared absorbing dye. A thermal transfer sheet comprising at least one hydrophilic polymer. (2) The above (1), wherein the light-heat conversion layer contains a salt of an infrared absorbing dye and an anionic polymer.
4. The thermal transfer sheet according to 1. (3) The above (1) or (2), wherein the anionic polymer has at least one of a sulfonate, a carboxylate and a phosphate as a repeating unit.
4. The thermal transfer sheet according to 1. (4) The thermal transfer sheet as described in any of (1) to (3) above, wherein the anionic polymer is soluble in an organic solvent. (4) The thermal transfer sheet according to any one of claims 1 to 3, wherein the infrared absorbing dye is a cationic dye having an absorption coefficient of 100,000 or more at 700 to 900 nm. (5) The image forming layer has a coloring material and a softening point of 40 to 150.
And 20 to 80% by weight of an amorphous organic high-molecular polymer in the temperature range of 0.2 to 1.degree.
The thermal transfer sheet according to any one of claims 1 to 4, wherein the thickness is in a range of 5 µm.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the thermal transfer sheet of the present invention will be described in detail. << Thermal transfer sheet >> The thermal transfer sheet of the present invention is a thermal transfer sheet provided with a light-to-heat conversion layer containing at least an infrared absorbing dye and an image forming layer on a support in this order,
The light-to-heat conversion layer contains at least one anionic polymer capable of forming a salt with an infrared-absorbing dye.The thermal transfer sheet of the present invention is an anionic polymer capable of forming an infrared-absorbing dye and a salt in the light-to-heat conversion layer. It is characterized by containing. In the present invention, the anionic polymer is an anion or a polymer capable of generating an anion by ionization, and means a polymer capable of forming a salt with an infrared absorbing dye. Therefore, in the light-to-heat conversion layer,
The presence or absence of a salt with the infrared absorbing dye is optional, but it is preferable that at least the salt be present. Examples of the anionic polymer capable of forming such a salt include a sulfonate, a carboxylate and a phosphate of the polymer. Infrared absorbing dyes that can form salts with these anions include cationic dyes. The cationic dye is a dye which is a cation or is capable of forming a cation upon ionization, and means a dye which can form a salt with an anionic polymer. It is preferable that the anionic polymer is soluble in an organic solvent in order to easily prepare a coating solution for a photothermal conversion layer containing a binder soluble in an organic solvent. The cationic dye has an extinction coefficient of 10 between 700 and 900 nm.
Those having an absorption of 0000 or more are preferable for performing image formation using laser light. The extinction coefficient is 15,000
0 or more is more preferable. In the thermal transfer sheet of the present invention, the image forming layer contains a colorant and an amorphous organic high molecular polymer having a softening point in the range of 40 to 150 ° C., each in an amount of 20 to 80% by weight, and has a thickness of Is preferably in the range of 0.2 to 1.5 μm, particularly for performing image formation using laser light.

Hereinafter, the components of the thermal transfer sheet will be further described. <Support> The material of the support of the thermal transfer sheet is not particularly limited, and various support materials can be used according to the purpose as long as they have excellent dimensional stability and can withstand heat during image formation. . Preferred examples of the support material include polyethylene terephthalate (PET), polyethylene-2,6
Rigid resin materials such as naphthalene, polycarbonate, polyethylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, and styrene-acrylonitrilo copolymer; Among them, biaxially stretched polyethylene terephthalate is preferred from the viewpoint of mechanical strength and dimensional stability against heat.

If an image is formed by irradiating a laser beam from the side of the support, the support is preferably transparent. The support need not be particularly transparent as long as an image is formed by irradiating a laser beam from the image forming layer side.

The support may have a cushioning property in order to increase the adhesiveness with the material to be transferred. In that case, it is preferable to use a material having a low elastic modulus or a material having rubber elasticity. Specifically, natural rubber, acrylate rubber, butyl rubber, nitrile rubber, butadiene rubber, isoprene rubber, styrene-butadiene rubber, chloroprene rubber, urethane rubber, silicone rubber, acrylic rubber, fluorine rubber, neoprene rubber, chlorosulfonated polyethylene , Epichlorohydrin, EPD
M, elastomers such as urethane lastomer, polyethylene, polypropylene, polybutadiene, polybutene, high-impact ABS resin, polyurethane, ABS resin, acetate, cellulose acetate, amide resin, polytetrafluoroethylene, nitrocellulose, polystyrene, epoxy resin, Phenol-formaldehyde resin, polyester, impact-resistant acrylic resin, styrene-
Butadiene copolymer, ethylene-vinyl acetate copolymer,
Acrylonitrile-butadiene copolymer, vinyl chloride-
Among the vinyl acetate copolymer, polyvinyl acetate, vinyl chloride resin containing a plasticizer, vinylidene chloride resin, polyvinyl chloride, polyvinylidene chloride, etc., resins having a small elastic modulus can be exemplified. These materials having a low elastic modulus or rubber elasticity may be blended in the base material of the support. Further, a shape memory resin such as polynorbornene or a styrene-based hybrid polymer in which a polybutadiene unit and a polystyrene unit are combined may be used.

The thickness of the support is not particularly limited, but is usually 2 to 300 μm, preferably 5 to 200 μm.
It is. The thickness of the support having cushioning properties varies depending on various factors such as the type of resin or elastomer used, the suction force at the time of close contact, the particle size of the mat material, the amount of the mat material used, etc. Although it cannot be performed, it is usually 10 to 100 μm.

(Backcoat layer) On the side of the support opposite to the side on which the light-to-heat conversion layer is provided, running stability, heat resistance,
A back coat layer having a function such as antistatic property may be provided. The back coat layer is a coating liquid for a back coat layer in which a resin such as nitrocellulose is dissolved in a solvent, or a coating for a back coat layer obtained by dissolving or dispersing a binder resin and fine particles of 20 to 30 μm in a solvent. It is formed by applying a liquid to the surface of the support.

(Cushion layer) A cushion layer can be provided between the support and the light-to-heat conversion layer. When dimensional stability is required or when a material having a low elastic modulus is used, it is preferable to provide a cushion layer on a support having no cushioning property, rather than providing the support with cushioning property. . As the material of the cushion layer, those mentioned as materials for forming the cushioning support can be used.

The thickness of the cushion layer is usually from 10 to 100.
μm is preferred. However, the present invention is not limited to this, and the type of resin or elastomer used, the suction force at the time of close contact,
It is preferable that the value be appropriately determined in consideration of various factors such as a granulometer of the mat material and the amount of the mat material used.

The cushion layer may be formed by dissolving or dispersing in the form of a latex in various kinds of solvents, using a blade coater, a roll coater, a bar coater, a curtain coater, a gravure coater, or the like, or an extrusion lamination method. Can be formed by

Although the adhesion is improved by providing the cushion layer, the time required for decompression during vacuum adhesion does not change much. On the contrary, too rapid decompression induces the formation of air pockets. In order to ensure sufficient adhesion and to reduce the time required for vacuum adhesion, it is preferable to roughen the thermal transfer sheet.

The surface of the thermal transfer sheet can be roughened by first roughening the surface of the cushion layer and then providing a light-to-heat conversion layer and an image forming layer, or by including a mat material on the surface of the thermal transfer sheet. And the like. The degree of the surface roughening is preferably determined by the elasticity of the cushion layer, the film thickness, the pressing force (degree of vacuum), the surface roughness of the thermal transfer sheet, the particle size of the mat member, and the amount added. In roughening the surface of the cushion layer, the surface roughness Ra is preferably in the range of 0.3 to 10 μm, though it depends on the material forming the cushion layer. The same applies to the case where the surface of the thermal transfer sheet is roughened.

<Light-to-heat conversion layer> The light-to-heat conversion layer contains a light-to-heat conversion substance, such as an infrared absorbing dye, an anionic polymer, a binder, and, if necessary, other components such as an additive and a matting material. The thickness of the light-to-heat conversion layer is preferably from 0.1 to 3 μm, more preferably from 0.1 to 1 μm. The optical density of the photothermal conversion layer at a wavelength of 600 to 1100 nm needs to be 0.3 to 2.0. If the optical density is less than 0.3, the irradiated light cannot be converted to heat. If the optical density exceeds 2.0, the light-to-heat conversion layer is destroyed at the time of recording and fog occurs.

(Infrared Absorbing Dye) In the photothermal conversion layer,
It is preferable to use an infrared absorbing dye as the light-to-heat conversion material. The photothermal conversion material refers to a material having a function of converting irradiated light energy into heat energy. In the thermal transfer sheet of the present invention, usable infrared absorbing dyes include indolenine dyes, polymethine dyes, phthalocyanine dyes, naphthalocyanine dyes, squarylium dyes, cyanine dyes, nitroso compounds and metal complex salts thereof, thiol nickel Salts, triallylmethane dyes, immonium dyes, naphthoquinone dyes, anthraquinone dyes, anthracene dyes, azulene dyes and the like can be mentioned. Specifically, JP-A-62-87388 and JP-A-63-2643
Nos. 95, 63-319191 and 64-3
No. 3547, JP-A-1-160683, 1
JP-A-280750, JP-A-1-293342, JP-A-2-2064, JP-A-2-2074, and 3-2
No. 6593, No. 3-30991, No. 3-30
Nos. 992, 3-34891 and 3-360
Nos. 93, 3-36094 and 3-3609
No. 5, JP-A-3-42281, and JP-A-3-63185.
JP-A-3-97589, JP-A-3-97590, JP-A-3-97591, JP-A-3-103476, JP-A-3-124488, and JP-A-3-132391.
Gazette, JP-A-4-140191, JP-A-4-16138
Nos. 2, 169,289 and 4,1692
Nos. 90, 4-173290, 4-173
Nos. 291 and 5-32058 and 5-201
Nos. 140, 5-221164, 5-33
No. 8358, No. 6-24143, No. 6-32.
Nos. 069 and 6-115263 and 6-21
JP-A-0987, JP-A-6-255271, JP-A-6-3
JP-A-99695, JP-A-7-101171 and JP-A-7-101171
Nos. 149049 and 7-172059 and 7
195830, 9-58143, 9
The compound group described in -80763, 10-2070665, 10-268512, 11-95026, or 11-302610 can be mentioned. Among them, as the infrared absorbing dye used in the present invention, a dye containing a methine group is preferable, and an indolenine dye is particularly preferable. Further, the light-to-heat conversion layer preferably contains two or more infrared absorbing dyes. The infrared absorbing dye is 700 to 900 as described above.
Cationic dyes having an absorption coefficient of 100,000 or more in nm are preferable, and examples thereof include the following. These can be used alone or in combination.

[0019]

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[0020]

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(Anionic polymer) An anionic polymer is added to the photothermal conversion layer. By adding an anionic polymer, it is possible to prevent the infrared absorbing dye and the like contained in the light-to-heat conversion layer from migrating to the image forming layer. It is possible to prevent image deterioration such as hue fluctuation of a recorded image due to fading of a decomposed product, and also prevent deterioration of transferability when re-transferring an image to a final material to be transferred. Become.

Examples of the anionic polymer include homopolymers and copolymers.
Those having at least one of the phosphates as a repeating unit are preferred. It is preferable that the repeating unit having a sulfonic acid salt, a carboxylate, or a phosphate structure is contained in an amount of 10 to 100% by mass, preferably 25 to 80% by mass in 100% by mass of the anionic polymer. The number average molecular weight of the anionic polymer is 1000 to 1000
000, preferably 2,000 to 300,000, more preferably 2,000 to 100,000. Within these ranges, the transfer of the infrared absorbing dye to the image forming layer is prevented, and the dye becomes soluble in an organic solvent. The polymer form of the anionic polymer may be a polymer obtained by any of addition polymerization, polycondensation and polyaddition, and is preferably an addition polymerization product of a vinyl monomer. The repeating unit having a sulfonate, carboxylate or phosphate structure of an anionic polymer can be represented by, for example, the following general formula (1). In addition, a sulfonic acid group, a carboxylic acid group, or a phosphoric acid group is called an acid group.

[0023]

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In the formula (1), R ¹ is a hydrogen atom, a methyl group,
Alternatively -X-R ² indicates -A ^1, R ³ represents a hydrogen atom or -X-R ² -A ^1, X is -CO-, -C (= O) O- , -CONH
-, -OC (= O)-, phenylene, a heterocyclic divalent group, R ²
Represents a divalent linking group or a single bond, and A ¹ represents a salt of an acid group. In the repeating unit represented by the formula (1), when two or more —X—R ² —A ¹ are present in the same unit,
X, R ² or A ¹ may be the same or different from each other. A plurality of units having different structures may be present in the same molecule. Specific examples of the repeating unit having a sulfonate are shown below, but are not limited thereto.

[0025]

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R ¹¹ represents a hydrogen atom or a methyl group. M
¹ is a monovalent metal cation (Na ion, K ion, etc.)
Alternatively, quaternary ammonium (tetramethylammonium, tetraethylammonium, tetrabutylammonium, benzyltrimethylammonium, benzyltriethylammonium, etc.) is shown. Specifically, the following are exemplified. Sodium, potassium, lithium, rubidium, cesium, tetramethylammonium, tetraethylammonium, tetrabutylammonium, tetrabutylammonium, styrenesulfonic acid, vinylbenzylsulfonic acid, and 2-acrylamido-2-methylpropanesulfonic acid Trimethylammonium salt, benzyltriethylammonium salt and the like. Specific examples of the repeating unit having a carboxylate are shown below, but are not limited thereto. Here, n represents an integer of 1 to 10. R represents a linking group having 1 to 4 carbon atoms, and the linking group may have a single or plural substituents, and the substituents are linked to each other to form a ring structure. May be. Also,
A hetero atom may be present in the linking group.

[0027]

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Specifically, the following are exemplified.
(Meth) acrylic acid (meaning of acrylic acid and methacrylic acid; the same applies hereinafter), itaconic acid, crotonic acid, fumaric acid, maleic acid, sodium salt, potassium salt, lithium salt, rubidium of styrene carboxylic acid salt,
Cesium salt, tetramethylammonium salt, tetraethylammonium salt, tetrabutylammonium salt, benzyltrimethylammonium salt, benzyltriethylammonium salt and the like. Specific examples of the repeating unit having a phosphate are shown below, but are not limited thereto.

[0029]

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M ² and M ³ each independently represent a hydrogen atom, 1
Valent metal cations (Na ions, K ions, etc.) or quaternary ammonium salts (tetramethylammonium, tetraethylammonium, tetrabutylammonium,
Benzyltrimethylammonium, benzyltriethylammonium, etc.), but at least one is not a hydrogen atom. Specifically, the following are exemplified. Mono-2- (meth) acryloylethyl phosphate, mono- or di-sodium salt, potassium salt, lithium salt, rubidium salt, cesium salt, tetramethylammonium salt, tetraethylammonium salt, tetrabutylammonium salt, monobenzyl phosphate of monovinyl phosphate, benzyl Trimethyl ammonium salt, benzyl triethyl ammonium salt, etc.

Examples of the copolymerizable component of the anionic polymer used in the present invention include aromatic vinyl compounds (eg, styrene, α-methylstyrene, p-hydroxystyrene, chloromethylstyrene and vinyltoluene), (meth) acrylic Acid alkyl esters (eg, methyl (meth)
Acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate),
(Meth) acrylic acid alkylaryl ester (eg, benzyl (meth) acrylate), (meth) acrylic acid-substituted alkyl ester (eg, glycidyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, dimethylaminoethyl (meth) Acrylate and dimethylaminopropyl (meth) acrylate), alkyl (meth) acrylamide (eg, (meth) acrylamide, dimethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, n-butyl (meth) acrylamide, tert-butyl ( (Meth) acrylamide and tert-octyl (meth) acrylamide), substituted alkyl (meth) acrylamide (eg, dimethylaminoethyl (meth) acrylamide and dimethylaminopropyl (meth) acrylamide), Lanka vinyl (e.g., (meth)
Acrylonitrile and α-chloroacrylonitrile),
Vinyl carboxylate (eg, vinyl acetate, vinyl benzoate, vinyl formate), aliphatic conjugated diene (eg, 1,3
-Butadiene and isoprene) and polymerizable oligomers (eg, methacryloylated polymethyl methacrylate oligomer at one end, methacryloylated polystyrene oligomer at one end, and methacryloylated polyethylene glycol at one end). One type of copolymerization component may be used, or two or more types may be used in combination.

Specific examples of the anionic polymer used in the present invention include sodium styrene sulfonate / methyl (meth)
Acrylate copolymer, vinyl benzyl sulfonate Na
/ Methyl (meth) acrylate copolymer, 2-acrylamide-2-methylpropanesulfonic acid Na / methyl (meth) acrylate copolymer, (meth) acrylic acid N
a / methyl (meth) acrylate copolymer, Na itaconate / methyl (meth) acrylate copolymer, Na maleate / methyl (meth) acrylate copolymer, Na crotonate / methyl (meth) acrylate copolymer, Na styrene carboxylate / methyl (meth) acrylate copolymer, mono-2- (meth) acryloylethyl phosphate sodium
Salt / methyl (meth) acrylate copolymer, monovinyl Na phosphate / methyl (meth) acrylate copolymer,
Na / butyl (meth) acrylate copolymer of styrene sulfonate, Na / benzyl (meth) styrene sulfonate
Acrylate copolymer, Na / 2-styrene sulfonic acid
Hydroxyethyl (meth) acrylate copolymer, Na styrene sulfonate / styrene copolymer, Na styrene sulfonate / α-methylstyrene copolymer, Na styrene sulfonate / dimethyl (meth) acrylamide copolymer, styrene sulfonic acid Na / dimethylaminoethyl (meth) acrylate copolymer, styrenesulfonic acid N
a / acrylonitrile copolymer, styrenesulfonic acid N
a / vinyl acetate copolymer, Na styrene sulfonate / vinyl benzoate copolymer, Na styrene sulfonate / methacryloylated polymethyl methacrylate oligomer copolymer at one end, Na styrene sulfonate / methacryloylated polystyrene oligomer copolymer at one end Unified, 2-acrylamide-2-methylpropanesulfonic acid Na / butyl (meth) acrylate copolymer, 2-acrylamide-
Na / benzyl 2-methylpropanesulfonate (meth)
Acrylate copolymer, 2-acrylamide-2-methylpropanesulfonic acid Na / 2-hydroxyethyl (meth) acrylate copolymer, 2-acrylamide-2-
Na methylpropanesulfonic acid / styrene copolymer, 2
-Acrylamido-2-methylpropanesulfonic acid Na
/ Α-methylstyrene copolymer, 2-acrylamide-
2-methylpropanesulfonic acid Na / dimethyl (meth)
Acrylamide copolymer, 2-acrylamide-2-methylpropanesulfonic acid Na / dimethylaminoethyl (meth) acrylate copolymer, 2-acrylamide-
Na 2-methylpropanesulfonic acid / acrylonitrile copolymer, 2-acrylamido-2-methylpropanesulfonic acid Na / vinyl acetate copolymer, 2-acrylamido-2-methylpropanesulfonic acid Na / vinyl benzoate copolymer, 2-acrylamido-2-methylpropanesulfonic acid Na / one-terminal methacryloylated polymethyl methacrylate oligomer, 2-acrylamido-2-methylpropanesulfonic acid Na / one-terminal methacryloylated polystyrene oligomer, styrenesulfonic acid K / methyl (meth) acrylate Copolymer, 2-acrylamido-2-methylpropanesulfonic acid K / methyl (meth) acrylate copolymer, styrenesulfonic acid tetramethylammonium / methyl (meth) acrylate copolymer,
2-acrylamido-2-methylpropanesulfonate tetramethylammonium / methyl (meth) acrylate copolymer, styrenesulfonate tetrabutylammonium / methyl (meth) acrylate copolymer, 2-acrylamido-2-methylpropanesulfonate tetra Butyl ammonium / methyl (meth) acrylate copolymer,
Benzyltrimethylammonium styrenesulfonate /
Methyl (meth) acrylate copolymer, benzyltrimethylammonium 2-acrylamido-2-methylpropanesulfonate / methyl (meth) acrylate copolymer and the like can be mentioned. These anionic polymers may be used alone or in combination of two or more. Preferably, the anionic polymer is soluble in an organic solvent.

The organic solvent is not particularly limited.
It can be appropriately selected from known ones, for example,
(Poly) alkylene glycol monoalkyl ethers and their acetic esters (eg, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 1- Methoxy-2-propyl acetate,
1-ethoxy-2-propyl acetate, etc.), acetates (eg, methyl acetate, ethyl acetate, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, etc.), aromatic hydrocarbons (Eg, benzene, toluene, xylene, etc.), ketones (eg, methyl ethyl ketone, acetone, methyl isobutyl ketone, cyclohexanone, etc.), alcohols (methanol, ethanol,
n-propanol, i-propanol, butanol, amyl alcohol, hexanol, cyclohexanol,
Ethylene glycol, diethylene glycol, glycerin, etc.), amides (N-methylpyrrolidone, N, N-
Dimethylformamide, N, N-dimethylacetamide, N, N′-dimethylimidazolidinone) and the like. These may be used alone or may be used alone.
More than one species may be used in combination. Among these, amides, ketones, alkylene glycol monoalkyl ethers and acetates thereof are preferred.

The preferred range of the amount of the anionic polymer contained in the light-heat conversion layer depends on the type of the infrared absorbing dye and the type of the anionic polymer. The ratio (molar ratio) of the site capable of forming the compound to the site capable of forming the infrared absorbing dye and the salt in the anionic polymer is
1: 0.5 to 1: 100, preferably 1: 0.
More preferably, the ratio is 5 to 1:50.

The anionic polymer contained in the light-to-heat conversion layer may be used alone or in combination of two or more.

The light-to-heat conversion layer is prepared by dissolving an infrared absorbing dye, an anionic polymer, and a binder described below, preparing a coating liquid to which additives and other components such as a matting material are added if necessary. It can be provided by coating and drying on a support. In preparing the coating solution for the light-to-heat conversion layer, as a solvent for dissolving the anionic polymer, a solvent for dissolving a binder described later can be similarly used.

(Binder) In general, the conditions required for the binder contained in the light-to-heat conversion layer include at least a strength capable of forming a layer on the support, a high glass transition point, and a high thermal conductivity. And high heat resistance without being decomposed by the heat generated even when high-energy irradiation is performed during image recording.

Examples of the binder having such properties include polyalkyl methacrylate, polyalkyl acrylate, polycarbonate, polystyrene, ethyl cellulose, nitrocellulose, polyester, polyurethane, acetyl cellulose, polyvinyl alcohol, and the like.
Suitable examples include general heat-resistant resins such as polyvinyl chloride, amide resins, polyimide, polyetherimide, polysulfone, polyethersulfone, and aramid. Among these, polyvinyl alcohol is particularly preferable because scattering of the light-heat conversion layer hardly occurs. In addition, polyimide is also soluble in an organic solvent, from the viewpoint of improving productivity, etc.,
Particularly preferred.

(Additive) The light-to-heat conversion layer may contain an additive, if necessary. The recording performance of the thermal transfer sheet or its coating liquid, such as a decrease in sensitivity and a decrease in resolution, decreases with the passage of time such as storage. In particular, it is remarkable under high temperature and high humidity. This is due to the decomposition of the infrared absorbing dye contained in the light-to-heat conversion layer. In addition, even when stored at room temperature, if it is stored for a long period of time, the infrared absorbing dye may be decomposed due to the influence of the residual solvent in the film and the like, which causes a reduction in recording performance. Further, even when the light-to-heat conversion layer is stored in the state of a coating solution, the infrared absorbing dye may be decomposed, and a predetermined optical density is not obtained, thereby deteriorating the image quality.

In order to prevent such a decrease in the recording performance of the thermal transfer sheet, it is preferable to add an additive having a quenching effect to a nucleophilic species or the like which causes the decomposition of the infrared absorbing dye in the light-to-heat conversion layer. Suitable examples of the additive include compounds having at least one functional group selected from a phosphoric acid ester, a phosphite, an acid anhydride, an acid halide, and an isocyanate. By containing it in the conversion layer, the decomposition of the infrared absorbing dye can be suppressed. These additives can prevent image quality deterioration due to decomposition of the infrared absorbing dye.

For specific examples of the compound having at least one functional group selected from the above-mentioned phosphoric esters, phosphites, acid anhydrides, acid halides and isocyanates, see Japanese Patent Application No. 2000-117056. It is described in detail in the book.

(Mat Material etc.) The light-to-heat conversion layer may contain a mat material as required. Examples of the mat material include inorganic fine particles and organic fine particles. As the inorganic fine particles, silica, titanium oxide, aluminum oxide, zinc oxide, magnesium oxide, sulfur barium, sulfur magnesium, aluminum hydroxide, magnesium hydroxide, metal salts such as boron nitride, kaolin, clay, talc, zinc white, Examples include lead white, ziglite, quartz, diatomaceous earth, barlite, bentonite, mica, and synthetic mica. Examples of the organic fine particles include fluorine resin particles, guanamine resin particles, acrylic resin particles, styrene-acryl copolymer resin particles, silicon resin particles, melamine resin particles, and epoxy resin particles. The particle size of the mat material is usually 0.3 to 30.
μm, preferably 0.5 to 20 μm, and the amount of addition is preferably 0.1 to 100 mg / m ² . If necessary, other components such as a surfactant, a thickener, and an antistatic agent may be added to the photothermal conversion layer.

<Image Forming Layer> In the thermal transfer sheet of the present invention, an image forming layer is provided on the light-to-heat conversion layer or a release layer described later. In the present invention, the image forming layer contains 20 to 80% by mass of a colorant and 20 to 80% by mass of an amorphous organic high molecular polymer having a softening point in a range of 40 ° C to 150 ° C.
It is preferred to include. The thickness (layer thickness) of the image forming layer is usually 0.1 to 3 μm, and 0.2 to 3 μm.
It is preferably in the range of 1.5 μm. The image forming layer may contain other components such as a matting material, if desired, in addition to the coloring material and the amorphous organic high molecular polymer. Incidentally, the image forming layer in the present invention means a layer which is melted or softened at the time of heating and is transferred to the material to be transferred. The image forming layer may not be transferred in a completely molten state.

(Coloring Material) The coloring material contained in the image forming layer includes a pigment or a dye. Pigments are generally divided into organic pigments and inorganic pigments, the former being particularly excellent in the transparency of the coating film,
The latter is generally excellent in hiding. As the inorganic pigment,
Examples include titanium dioxide, carbon black, zinc oxide, Prussian blue, cadmium sulfide, iron oxide, and chromates of lead, zinc, barium, and calcium. As the organic pigment, azo pigments, thioindigo pigments, anthraquinone pigments, anthanthronic pigments, triphenedioxazine pigments, vat dye pigments, isoindolinone pigments, nitro pigments, phthalocyanine pigments such as copper phthalocyanine And its derivatives and quinacridone pigments. The content of the pigment in the image forming layer is preferably from 20 to 80% by mass.

Further, a dye may be used as a coloring material. Examples of the organic dye include an acid dye, a direct dye, a disperse dye, an oil-soluble dye, a metal-containing oil-soluble dye, and a heat sublimable dye.Examples of the heat sublimable dye include a cyan dye, a magenta dye, and the like. Yellow dyes are preferred.

The cyan dye is described in JP-A-59-7.
Nos. 8896, 59-227948, 60
Nos. 24966, 60-53563, and 6
Nos. 0-130735, 60-131292, 60-239289, and 61-19396.
Gazette, JP-A-61-22933, JP-A-61-2129
No. 2, No. 61-31467, No. 61-359
Nos. 94, 61-49893, 61-14
Nos. 8269 and 62-191191 and 63
-91288, 63-91287, 6
Examples include naphthoquinone dyes, anthraquinone dyes, and azomethine dyes described in JP-A-3-290793.

The magenta dye is described in JP-A-59-1984.
No. 78896, JP-A-60-30392, JP-A-60-60
-30394, JP-A-60-253595, JP-A-61-262190, JP-A-63-5992, JP-A-63-205288, JP-A-64-159, JP-A-64-63194 Anthraquinone dyes, azo dyes, azomethine dyes, etc. described in each publication such as No.

The yellow dye is described in JP-A-59-1984.
No. 78896, JP-A-60-27594, JP-A-60-60
-31560, JP-A-60-53565, JP-A-6
Examples thereof include methine dyes, azo dyes, quinophthalone dyes, and anthrisothiazole dyes described in JP-A Nos. 11-12394 and 63-122594.

Among the above-mentioned heat sublimable dyes, a compound having an open-chain or closed-type active methylene group is obtained by a coupling reaction with an oxidized p-phenylenediamine derivative or an oxidized p-aminophenol derivative. An azomethine dye or a compound having an open-chain or closed-type active methylene group, a phenol or naphthol derivative, p
Particularly preferred is an indaniline dye obtained by a coupling reaction with an oxidized form of a phenylenediamine derivative or an oxidized form of a p-aminophenol derivative.

The thermo-sublimable dye contained in the image forming layer may be a yellow dye if the image to be formed is a single color.
Any of a magenta dye and a cyan dye may be used.

The content of the coloring material in the image forming layer is as follows:
Usually, it is 5 to 70% by mass, preferably 20 to 80% by mass, and more preferably 30 to 70% by mass.

(Binder-amorphous organic high molecular polymer-)
Examples of the binder (binder) that can be used in the image forming layer according to the invention include a heat-fusible substance, a heat-softening substance, and a thermoplastic resin. The heat-fusible substance generally refers to a solid or semi-solid substance having a melting point in the range of 40 to 150 ° C. measured using a Yanagimoto MJP-2 type.

Specific examples of the above-mentioned heat-fusible substances include, for example, vegetable waxes such as carnauba wax, wood wax, ouriculi wax and Espal wax; animal waxes such as beeswax, insect wax, shellac wax and spermaceti; paraffin wax; Crystallin wax, polyethylene wax,
Petroleum waxes such as ester waxes and acid waxes; and waxes such as mineral waxes such as montan wax, ozokerite and ceresin. In addition to these waxes, palmitic acid, stearic acid,
Higher fatty acids such as margaric acid and behenic acid; higher alcohols such as palmityl alcohol, stearyl alcohol, behenyl alcohol, marganyl alcohol, myricyl alcohol and eicosanol; cetyl palmitate, myristyl palmitate, cetyl stearate and myricyl stearate And higher amines such as acetamide, propionamide, palmitic amide, stearamide and amide wax; and higher amines such as stearylamine, behenylamine and palmitylamine. They may be used or may be used in combination.

Specific examples of the heat-softening substance include waxes such as vegetable wax, animal wax, petroleum wax, and mineral wax. In addition to these waxes, higher fatty acids, higher alcohols, Higher fatty acid esters, amides, higher amines, and a softening point of 40 ° C to 1
An amorphous organic high-molecular polymer having a temperature of 50 ° C. is preferably used.

Specific examples of the amorphous organic high molecular polymer having a softening point of 40 ° C. to 150 ° C. include, for example, polyvinyl butyral resin, butyral resin, polyamide resin, polyethylene imine resin, sulfonamide resin, and polyester polyol resin. Styrene, such as petroleum resin, styrene, vinyltoluene, α-methylstyrene, 2-methylstyrene, chlorostyrene, vinylbenzoic acid, sodium vinylbenzenesulfonate, aminostyrene and derivatives thereof, and homopolymers and copolymers of substituted derivatives Methacrylates such as coalesce, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate and methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, α-ethylhexyl acrylate, etc. Acrylic esters and dienes such as acrylic acid, butadiene, isoprene, acrylonitrile, vinyl ethers, maleic acid and maleic esters, maleic anhydride, cinnamic acid, vinyl chloride, vinyl acetate and other vinyl monomers. Examples of the polymer include a polymer and a copolymer of the vinyl monomer and another monomer. These resins can be used as a mixture of two or more kinds.

Specific examples of the thermoplastic resin include ethylene copolymers, polyamide resins, polyester resins, polyurethane resins, polyolefin resins, acrylic resins, vinyl chloride resins, cellulose resins, and rosin resins. Resins such as resins, ionomer resins and petroleum resins; elastomers such as natural rubber, styrene butadiene rubber, isoprene rubber and chloroprene rubber; rosin derivatives such as ester gum, rosin maleic resin, rosin phenol resin and hydrogenated rosin; And high molecular compounds having a softening point of 40 to 150 ° C. such as phenol resins, terpene resins, cyclopentadiene resins, and aromatic hydrocarbon resins.

Among the above binders, the softening point is from 40 ° C. to 15 ° C.
It is preferable to use an amorphous organic high molecular polymer at 0 ° C. The content of the amorphous organic high molecular polymer in the image forming layer is preferably from 20 to 80% by mass, more preferably from 30 to 70% by mass, and particularly preferably from 40 to 60% by mass.

(Mat Material) A mat material can be added to the image forming layer. When the support has cushioning properties, or when a cushion layer that has not been subjected to surface roughening treatment is provided on the support, a matting material is added to the image forming layer to roughen the surface. Is preferred. Examples of the mat material include inorganic fine particles and organic fine particles. As the inorganic fine particles, silica, titanium oxide, aluminum oxide, zinc oxide, magnesium oxide, barium sulfate, magnesium sulfate, aluminum hydroxide, magnesium hydroxide, metal salts such as boron nitride, kaolin, clay, talc, zinc white, Examples include lead white, ziglite, quartz, diatomaceous earth, perlite, bentonite, mica, and synthetic mica. As the organic fine particles, fluorine resin particles, guanamine resin particles, acrylic resin particles, styrene-acryl copolymer resin particles,
Resin particles such as silicon resin particles, melamine resin particles, and epoxy resin particles can be used.

In addition, when the thermal transfer sheet and the material to be transferred are superimposed on each other and pressurized or heated and pressurized at the time of image transfer, a mat material which is crushed by the pressure is contained in the thermal transfer sheet, so that the support can have a cushion. The same effect can be achieved without providing a cushion layer.

As a mat material that is crushed when pressed,
Fine particles formed of a material having rubber elasticity can be used. Specifically, acrylate rubber, butyl rubber, nitrile rubber, butadiene rubber, isoprene rubber, styrene-butadiene rubber, chloroprene rubber, urethane rubber, silicone rubber, acrylic rubber, fluorine rubber, neoprene rubber, chlorosulfonated polyethylene, epichlorohydrin, Elastomers such as EPDM; Further, as the mat material which is crushed by heating and pressing, fine particles made of low hardness wax such as paraffin wax, beeswax, wax having a large oil content, and wax having a large low molecular weight component can be used. The thermal transfer sheet roughened by the wax fine particles can be manufactured by forming at a temperature lower than the melting start temperature of the wax forming the fine particles by 10 ° C. or more.

The particle size of the mat material is usually 0.3 to 30 μm.
m, preferably 0.5 to 20 μm, and the amount of addition is 0.1 to 100 mg / m ² .

(Other Components) The image forming layer further comprises
In addition to the components described above, surfactants, inorganic or organic fine particles (metal powder, silica gel, etc.), oils (linseed oil, mineral oil, etc.) and the like may be contained. Except for obtaining a black image, the energy required for transfer can be reduced by including a substance that absorbs the wavelength of the light source used for image recording. The substance absorbing the wavelength of the light source may be a pigment or a dye, but when a color image is obtained, an infrared light source such as a semiconductor laser is used for image recording, and the absorption in the visible portion is small. It is preferable from the viewpoint of color reproduction to use a dye having a large absorption at the wavelength of the light source. Specific examples of the near infrared dye include compounds described in JP-A-3-103476.

<Scattering Prevention Layer> When high-density energy such as a laser is used as a light source, heat generated by the photothermal conversion layer rapidly absorbing light energy is used.
In order to prevent the light-to-heat conversion material or the binder from scattering, a scattering prevention layer may be provided between the light-to-heat conversion layer and the image forming layer. As the scattering prevention layer, the strength capable of suppressing scattering of the light-to-heat conversion layer with a thin film, and the heat generated in the light-to-heat conversion layer can be quickly transferred to the image forming layer.
It is preferable to use a material having high thermal conductivity. The scattering prevention layer is formed of a general heat-resistant resin or the like similarly to the binder of the light-to-heat conversion layer. Among them, polyvinyl alcohol has a large effect of preventing scattering, and can be dissolved in water and applied. It is preferable because it is less mixed with the image forming layer and the light-to-heat conversion layer. When light is irradiated from the support side of the thermal transfer sheet, the scattering prevention layer may be opaque, and a metal deposited film of aluminum or the like has a scattering prevention effect. The thinner the anti-scattering layer, the higher the sensitivity, and the thicker the anti-scattering layer, the more effective the anti-scattering effect.

<Release Layer> A release layer can be provided between the photothermal conversion layer and the image forming layer. The presence of the peeling layer facilitates peeling of the image forming layer during thermal transfer recording, so that a high quality image can be obtained. The release layer can be composed of the heat-fusible compound itself, but is usually preferably composed of the heat-fusible compound and / or a binder resin such as a thermoplastic resin.

The heat-fusible compound used as the main component of the release layer may be appropriately selected from known compounds and used. Specific examples thereof include, for example, Japanese Patent Application Laid-Open No. 63-193.
No. 886, page 4, upper left column, line 8 to upper right column, line 12
Exemplary materials can be used by line.

Specific examples of the thermoplastic resin include, for example, an ethylene copolymer such as an ethylene-vinyl acetate resin, a polyamide resin, a polyester resin, a polyurethane resin, a polyolefin resin, an acrylic resin, and a cellulose resin. And the like. In addition, for example, resins such as vinyl chloride resin, rosin resin, petroleum resin and ionomer resin, elastomers such as natural rubber, styrene butadiene rubber, isoprene rubber and chloroprene rubber, ester gum, rosin maleic acid resin, rosin Rosin derivatives such as phenolic resins and hydrogenated rosins, as well as phenolic resins, terpene resins, cyclopentadiene resins, aromatic resins, and the like can be used as appropriate.

In the present invention, the thermoplastic resin which can be used as a component of the release layer has a melting point or a softening point of usually 50 to 150 ° C. among the thermoplastic resins exemplified above.
In particular, those in the range of 60 to 120 ° C or those in the range by mixing two or more kinds are preferably used.

<Production of Thermal Transfer Sheet> To produce the thermal transfer sheet of the present invention, first, the above-mentioned components for forming each layer are mixed while heating, or dispersed or dissolved in a solvent to form a coating solution for forming each layer. Is prepared. Then, these coating liquids are sequentially applied to the surface of the support, and the solvent is dried if necessary, whereby a desired thermal transfer sheet can be obtained.

As the solvent for preparing the coating solution,
Water, alcohols (eg, ethanol, methanol), cellosolves (eg, methyl cellosolve, ethyl cellosolve), aromatics (eg, toluene, xylene, chlorobenzene), ketones (eg, acetone, methyl ethyl ketone), ester solvents ( Examples thereof include ethyl acetate, butyl acetate), ethers (eg, tetrahydrofuran, dioxane), and chlorinated solvents (eg, chloroform, trichloroethylene).

As a coating method, a conventionally known coating method using a gravure roll, an extrusion coating method, a wire bar coating method, a roll coating method and the like can be adopted.

The image forming layer covers the entire surface of the support,
Alternatively, on a part of the surface, it may be formed as a layer containing a single color material, or a yellow image forming layer containing a binder and a yellow dye, a magenta image forming layer containing a binder and a magenta dye, and A cyan image forming layer containing a binder and a cyan dye,
It may be formed on the entire surface or a part of the surface of the support at a constant repetition along the plane direction. Also,
The image forming layers of these colors may be laminated.

The use of the thermal transfer sheet can be facilitated by forming perforations or providing detection marks for detecting the positions of areas having different hues.

<< Transferred Material >> In order to form an image by receiving the image forming layer imagewise peeled from the thermal transfer sheet, a transferred material is used as a final image recording medium. Normal,
The transfer material has a support and one or more image receiving layers thereon, but may be formed only from the support. Further, a cushion layer or the like may be provided between the support and the image receiving layer.

Since the transfer material transfers the image-forming layer melted by heat, the transfer material must have appropriate heat resistance and excellent dimensional stability so that an image can be formed properly. preferable.

(Support) As the support for the material to be transferred, polyethylene as long as an image (transmission image) that can be seen through from the surface opposite to the surface having the transferred image is formed. And resin films or resin sheets of polypropylene, polyethylene terephthalate, polystyrene, polyvinyl chloride and polyimide. On the other hand, if an image (reflection image) that cannot be seen through from the surface opposite to the surface having the transferred image and can be seen only from the transfer surface side is formed, the support may be a resin film or a resin film. Examples thereof include white films formed by adding a white pigment such as barium sulfate, calcium carbonate, and titanium oxide to a resin sheet, and papers such as coated paper, art paper, and RC paper.

When a cushioning property is imparted to the support, the support may be formed of the above-mentioned material imparting the cushioning property.
The support may be formed by a composite film or sheet in which a film or sheet made of a material imparting cushioning properties is compounded.

(Image receiving layer) The image receiving layer comprises a binder,
It is formed from various additives that are added as needed. When the support does not have a cushioning property, a material for imparting the above-described cushioning property to the image receiving layer may be added.

The binder to be added to the image receiving layer includes an ethylene-vinyl chloride copolymer adhesive, a polyvinyl acetate emulsion adhesive, a chloroprene adhesive,
Adhesives such as epoxy resin adhesives, natural rubber, chloroprene rubber, butyl rubber, polyacrylate, nitrile rubber, polysulfide, silicon rubber, rosin resin, vinyl chloride resin, petroleum resin and Adhesives such as ionomer resin, recycled rubber, SBR,
Examples include polyisoprene and polyvinyl ether.

(Cushion Layer) In the transfer-receiving material, a cushion layer may be provided between the support and the image receiving layer instead of providing the support and the image receiving layer with cushioning properties.
In this case, the cushion layer is the same as the cushion layer in the thermal transfer sheet. The thickness of the support in the transfer material having the support, the cushion layer, and the image receiving layer or the thickness of the support in the transfer material formed only of the support is not particularly limited. The thickness of the cushion layer is the same as the thickness of the cushion layer in the thermal transfer sheet. The thickness of the image receiving layer is usually 0.1 to 20 μm, but is not limited to the case where the cushion layer is used as the image receiving layer.

The surface of the material to be transferred which comes into contact with the thermal transfer sheet during image formation has good smoothness or is appropriately roughened. More specifically, when the surface of the image forming layer of the thermal transfer sheet is roughened by the above-described addition of the mat material or the roughening of the cushion layer, the surface of the material to be transferred which comes into contact with the image forming layer is It is preferable to have good smoothness. On the other hand, when the image forming layer is not roughened, the surface where the material to be transferred comes into contact with the image forming layer has been roughened by the addition of the mat material and the roughening of the cushion layer. Is preferred. Further, both the image forming layer and the surface of the transfer material that contacts the image forming layer may be roughened. When both the thermal transfer sheet and the material to be transferred were not roughened, the material to be transferred having the cushion layer was subjected to a surface roughening treatment immediately before the two were brought into close contact with each other, and the surface was roughened in a state of being vacuum-contacted. However, it is preferable to smooth again.

(Mat Material) The mat material is the same as that described for the thermal transfer sheet. Further, by using a mat material that is crushed by pressurization or heating and pressurization, it is not necessary to provide a support having a cushioning property, an image receiving layer, or a cushion layer on the material to be transferred. It is the same as when using.

By using a mat material for the thermal transfer sheet or the material to be transferred and by appropriately roughening the contact surface between the thermal transfer sheet and the material to be transferred, the inconvenience due to excessive mutual contact between the surfaces can be solved. be able to. On the other hand, the problems caused by the use of the mat material, that is, the occurrence of uneven adhesion, reduced resolution, and color turbidity can be eliminated by imparting cushioning properties to the material to be transferred.

The transfer material can be used as a final image recording medium when an image is transferred and formed by the thermal transfer sheet.

It is to be noted that a variety of thermal transfer sheets having color materials having different colors from each other and one transfer material are used.
When a single-color image forming layer is transferred imagewise for each thermal transfer sheet to form a multicolor or full-color transfer image, the material to be transferred preferably has cushioning properties. In particular, it is preferable that the support having the cushioning property or the cushion layer is formed of a shape memory resin that can be restored. Examples of the shape memory resin include those described above.

(Intermediate Transfer Body) In general, when an image forming layer is image-wise thermally transferred to a material to be transferred by a thermal transfer sheet,
In order to obtain a transferred image with high image quality, the surface of the material to be transferred is preferably smooth. In other words, a high-quality image cannot be recorded on a material to be transferred having a low surface smoothness. Therefore, in order to form a high quality image on a transferred material having a low surface smoothness, a thermal transfer sheet is used.
It is preferable to temporarily transfer an image to a transfer material as an intermediate transfer member having a high surface smoothness, and then retransfer the image of the intermediate transfer member to a transfer material having a low surface smoothness.

This intermediate transfer member can have the same configuration as the material to be transferred. However, the intermediate transfer member needs to have cushioning properties. Further, the intermediate transfer member does not need to be roughened. When the intermediate transfer member has a cushion layer, the thickness of the intermediate transfer member is, for example, generally 10 to 20 μm when using high-quality paper.
It is preferably at least 0 μm.

It is desired that the intermediate transfer member has good receptivity of the image forming layer and good retransferability to the final material to be transferred. Examples of the intermediate transfer member having such characteristics include polyethylene, polypropylene, low VA type ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer (EEA), ethylene-methacrylate copolymer (EMA), Ethylene-methyl methacrylate copolymer (EMMA), ethylene-vinyl acetate copolymer, ionomer resin, chlorinated ethylene, chlorinated polypropylene, chlorinated polyolefin, butadiene rubber, isoprene rubber, SBR, SBS, SIP, polyvinyl butyral, Polyvinyl acetal, polyvinyl ether, polyvinyl alcohol, polyvinyl pyrrolidone, olefin polymers such as various acrylic resins, polyester resins, polyurethane resins, polyamide resins, nitrocellulose, cellulose acetate Scan, celluloses such as ethyl cellulose, fluorocarbon resins, and silicone resins.

The intermediate transfer member is superimposed on the final transfer material, and the image of the intermediate transfer member is re-transferred to the surface of the final transfer material by pressing or heating and pressing. If a monochrome image is to be re-transferred, one type of transfer material as an intermediate transfer body and one type of final transfer material are used.
Multicolor retransfer image or full color retransfer image
When transferring to the final transfer material, a plurality of types of intermediate transfer members may be used for one final transfer material, or multi-color or full-color transfer onto one intermediate transfer member. The image may be transferred and retransferred to the final transferred material.

Regardless of whether a monochrome image is retransferred or a multicolor image or a full-color image is retransferred, a method of retransferring the entire image receiving layer of the intermediate transfer member to the final transfer receiving material, Any of the techniques for retransferring the transferred image on the intermediate transfer member without transferring the layer can be adopted.

If only the image is to be retransferred without retransfer of the image receiving layer, the image receiving layer of the intermediate transfer member is preferably non-adhesive to the final material to be transferred. Also,
If you re-transfer while heating, when re-transfer,
It is desired that the image receiving layer in the intermediate transfer member is not heat-sealable. In addition, when employing the technique of retransferring while heating, the image receiving layer and the cushion layer of the intermediate transfer body are not easily separated by heat, for example, an adhesive layer is interposed between the image receiving layer and the cushion layer. Ingenuity such as is required. When the image is re-transferred together with the image receiving layer of the intermediate transfer member, it is preferable to provide a release layer between the image receiving layer and the cushion layer, contrary to the above.

The material to be transferred and the intermediate transfer member having a cushion layer and an image receiving layer on a support are mixed with each other while heating the above-mentioned various components for forming each layer, or dispersed or dissolved in a solvent to form each layer. It can be obtained by preparing a coating liquid, then coating the coating liquid on a support and, if necessary, drying the solvent.

Examples of the solvent used for applying each layer forming solution coating solution include water, alcohols (eg, ethanol,
Propanol), cellosolves (eg, methyl cellosolve, ethyl cellosolve, etc.), aromatics (eg, toluene, xylene, chlorobenzene, etc.), ketones (eg, acetone, methyl ethyl ketone, etc.), ester solvents (eg, ethyl acetate, butyl acetate, etc.) ), Ethers (eg, tetrahydrofuran, dioxane, etc.), chlorinated solvents (eg, methylene chloride, chloroform, trichloroethylene, etc.).

For coating each layer forming solution coating solution, a conventionally known coating method using a gravure roll, an extrusion coating method, a wire bar coating method, a roll coating method, or the like can be adopted. In addition to the above coating method, the image receiving layer can be formed by a hot melt extrusion lamination method in which a mixture having a component for forming the image receiving layer is melt-extruded and laminated.

The hot melt extrusion
Lamination by the lamination method is disclosed in Japanese Patent Application Laid-Open No. 1-2630.
No. 81, No. 1-271289, No. 2-106397
2-111586, 2-305688, 3-49991 and the like.

<< Image Formation >><MonochromeImage> A thermal transfer recording method for forming a monochrome image using the thermal transfer sheet of the present invention is performed as follows. First, a thermal transfer sheet and a material to be transferred are placed on a substrate so as to overlap with each other. In this case, the thermal transfer sheet may be placed first on the substrate, or the material to be transferred may be placed first.

As the substrate, any of a cylindrical drum and a flat substrate can be used. Preferred is a cylindrical drum. When a cylindrical drum is used as a substrate, a transfer image can be formed at high speed by high-speed rotation. Further, the energy efficiency when using laser light or the like can be increased by reducing the space of the light irradiation system and simplifying the optical system. As a result, the size of the device can be reduced.

At this time, the thermal transfer sheet and / or the material to be transferred are brought into close contact with the substrate. The means for adhering the thermal transfer sheet or the material to be transferred is not particularly limited. For example, a large number of through holes are provided in the substrate, and the heat transfer sheet or the material to be transferred is exhausted from the through holes by the exhaust means. Means for fixing can be given.

When the material to be transferred is brought into close contact with the substrate, a cover sheet may be placed on the laminate of the thermal transfer sheet and the material to be transferred, or the size of the sheet outside the substrate may be increased, if necessary, in order to improve the adhesion. Can be slightly larger than the size of the sheet on the inside. A method for adhering and detaching two sheets separately is disclosed in JP-A-63-87.
No. 031. In order to shorten the adhesion time, it is preferable to reduce the pressure while squeezing the thermal transfer sheet and the material to be transferred. Further, when at least one of the thermal transfer sheet and the material to be transferred has a cushion layer, once squeezing is performed while strongly reducing the pressure, the degree of vacuum necessary to maintain the adhesion is small even if the degree of vacuum is small. Good. Therefore, once the degree of vacuum is sufficiently increased in the close contact step, the degree of vacuum during recording is not required so much, which is advantageous in terms of device design.

The degree of vacuum required for the vacuum contact depends on the degree of surface roughening of the thermal transfer sheet and the material to be transferred, but is preferably from 13.3 to 4.67 × 10 ⁴ Pa. It may be even lower. The pressing force when pressing the laminate of the thermal transfer sheet containing the mat material and the material to be transferred is usually 0.1 to 5 kg / cm.
² (9.8 to 490 kPa) is preferred. When using a mat material with a small particle size, the pressing force may be small, while when using a mat material with a large particle size,
The pressing force needs to be increased.

After the laminate is brought into close contact with the substrate, if the substrate is transparent, light such as a laser beam is irradiated imagewise from the back side of the substrate or from the cover sheet side. The laser light is converted into heat by the infrared absorbing dye contained in the thermal transfer sheet, and the image forming layer adheres imagewise to the material to be transferred. Thereafter, when the thermal transfer sheet and the material to be transferred are separated, a material to be transferred having a monochromatic image adhered imagewise can be obtained.

<Multicolor, full-color image> In order to obtain a multicolor image or a full-color image, first, a cyan image forming layer, a magenta image forming layer, and a yellow image forming layer are sequentially formed on a support. A heat transfer sheet is prepared. Alternatively, a monochromatic thermal transfer sheet having a cyan image forming layer on a support, a monochromatic thermal transfer sheet having a magenta image forming layer on a support, and a monochromatic thermal transfer sheet having a yellow image forming layer on a support Prepare

Next, the material to be transferred is fixed on the substrate by a suction action, and a thermal transfer sheet is stacked thereon. In addition,
When forming a multi-color image or a full-color image,
It is necessary to replace the thermal transfer sheet many times while the material to be transferred is brought into close contact with the substrate by suction. Therefore, in order to form an image in a short time, it is preferable not to use a cover sheet.

As described above, light is irradiated imagewise to form, for example, a cyan image on the surface of the transfer material, and the thermal transfer sheet is peeled off from the surface of the transfer material. Next, heat transfer sheets of different colors are superimposed, and light is similarly irradiated imagewise to form a magenta image, for example. After the image is formed, the thermal transfer sheet is peeled from the material to be transferred, and a thermal transfer sheet of another color is superimposed on the material to be transferred. Next, light is irradiated imagewise to form, for example, a yellow image.

Note that while replacing a plurality of thermal transfer sheets,
It is necessary to fix the material to be transferred on the substrate so that color shift does not occur. For this purpose, it is preferable that the surface of the substrate is formed of, for example, an adhesive material, and that the material to be transferred is fixed on the substrate by a suction force by exhaust even when the thermal transfer sheet is replaced.

When the material to be transferred has a cushion layer formed of a shape memory resin, the cushion layer is heated to recover its shape every time one color is transferred.

The above-mentioned method can be used for transferring an image to the intermediate transfer member. By using the thus obtained intermediate transfer body having an image on the surface, a fine image can be formed even on a material to be transferred whose surface is not smooth.

[0107]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.
In the following description, “parts” means “parts by mass” unless otherwise specified.

Example 1 Preparation of Thermal Transfer Sheet C (Cyan) 1) Preparation of Coating Solution for Light-to-Heat Conversion Layer The following components were mixed while stirring with a stirrer to prepare a coating solution for a light-to-heat conversion layer. did. [Coating solution composition for photothermal conversion layer] 7.6 parts of infrared absorbing dye ("S0086", manufactured by Huchemical Co., Ltd.)

[0109]

Embedded image

• Anionic polymer (Compound 1) 14.7 parts

[0111]

Embedded image

• 14.7 parts of polyimide resin • 1500 parts of N, N-dimethylformamide • 360 parts of methyl ethyl ketone • 0.5 part of surfactant (“MegaFac F-177”, manufactured by Dainippon Ink and Chemicals, Inc.) • Matt 1.7 parts ("Sea Hostar KEP150": silica gel particles, manufactured by Nippon Shokubai Co., Ltd.)

2) Formation of Light-to-Heat Conversion Layer on Support Surface The above-mentioned coating solution for a light-to-heat conversion layer was coated on one surface of a 75 μm-thick polyethylene terephthalate film (support) using a wire bar. 120 ° C
After drying in an oven for 2 minutes, a light-to-heat conversion layer was formed on the support. The optical density of the obtained light-to-heat conversion layer at a wavelength of 808 nm was measured with a UV-spectrophotometer UV-240 manufactured by Shimadzu Corporation and found to be OD = 1.20. The thickness of the layer was 0.3 μm on average when the cross section of the light-to-heat conversion layer was observed with a scanning electron microscope.

3) Preparation of Coating Solution for Cyan Image Forming Layer The following components were put into a kneader mill, and pre-dispersion treatment was carried out by applying a shearing force while adding a small amount of solvent. A solvent was further added to the dispersion, and the dispersion was finally adjusted to have the following composition, followed by sand mill dispersion for 2 hours to obtain a pigment dispersion mother liquor. [Cyan pigment dispersed mother liquor composition]-12.6 parts of polyvinyl butyral ("ESLEC B BL-SH", manufactured by Sekisui Chemical Co., Ltd.)-15.0 parts of pigment (Cyan pigment (Pigment Blue 15, # 700-10) FG CY-Blue ")-Dispersing aid 0.8 parts (" PW-36 ", manufactured by Kusumoto Kasei Co., Ltd.)-n-propyl alcohol 110 parts

[Composition of Cyan Image Forming Layer Coating Solution] 118 parts of the above-mentioned cyan pigment-dispersed mother liquor 5.2 parts of polyvinyl butyral (“ESREC B BL-SH”, manufactured by Sekisui Chemical Co., Ltd.) wax compound 1.0 part (behenamide "Diamid BM", manufactured by Nippon Kasei Co., Ltd.) 1.0 part (lauric amide "Diamid Y" 1.0 part (palmitinamide "Diamind KP", Nippon Kasei Co., Ltd.) 1.0 part (erucamide "Diamid L-200" (Nippon Kasei Co., Ltd.) 1.0 part (Oleic acid amide “Diamid O-200” manufactured by Nippon Kasei Co., Ltd.) 1.0 part ・ Rosin 2.8 parts (“KE-311” manufactured by Arakawa Chemical Co., Ltd.) Monomer 1.7 ("PET-4A", manufactured by Shin-Nakamura Chemical Co., Ltd.)-1.7 parts of surfactant ("Megafac F-176P", solid content 20%, manufactured by Dainippon Ink and Chemicals, Inc.)-n-propyl alcohol 890 parts ・ methyl ethyl ketone 247 parts The particles in the obtained cyan image forming layer coating solution were measured using a laser scattering type particle size distribution analyzer to find that the average particle size was 0.25 μm, The proportion was 0.5%.

4) Formation of Cyan Image Forming Layer on Surface of Light-to-Heat Conversion Layer The above-mentioned coating solution for a cyan image forming layer was applied to the surface of the light-to-heat conversion layer for 1 minute using a wheeler, and then the coated material was applied to
After drying in an oven at 00 ° C. for 2 minutes, a cyan image forming layer was formed on the light-to-heat conversion layer. Through the above steps, a thermal transfer sheet C in which the light-to-heat conversion layer and the cyan image forming layer were provided in this order on the support was produced. Optical density (optical density: OD) of cyan image forming layer of thermal transfer sheet C
, Macbeth densitometer "TD-904" (W filter)
Was OD = 0.91. When the thickness of the cyan image forming layer was measured, it was 0.45 μm on average.
Met. The content of the pigment in the cyan image forming layer was 32% by mass, and the content of polyvinyl butyral was 40% by mass.

—Preparation of Transferred Material— A coating solution for a cushion layer and a coating solution for an image receiving layer having the following compositions were prepared. 1) Coating solution for cushion layer-20 parts of vinyl chloride-vinyl acetate copolymer ("MPR-TSL", manufactured by Nissin Chemical Co., Ltd.)-10 parts of plasticizer ("Paraplex G-40", CP.HALL)・ Company; ・ Surfactant 0.5 part (“MegaFac F-177”, manufactured by Dainippon Ink & Chemicals, Inc.) ・ Antistatic agent 0.3 part (“SAT-5 Super (IC)”) , Manufactured by Nippon Junyaku Co., Ltd.) ・ Methyl ethyl ketone 60 parts ・ Toluene 10 parts ・ N, N-dimethylformamide 3 parts

2) Coating Solution for Image Receiving Layer ・ Polyvinyl Butyral 8 parts (“ESLEC B BL-SH”, manufactured by Sekisui Chemical Co., Ltd.) ・ Antistatic agent 0.7 parts (“Sunstat 2012A”, Sanyo Chemical Industries, Ltd.)・ Surfactant 0.1 part (“MegaFac F-177”, manufactured by Dainippon Ink & Chemicals, Inc.) ・ n-propyl alcohol 20 parts ・ Methanol 20 parts ・ 1-methoxy-2- 50 parts of propanol

Using a small width applicator, a white PET support (“Lumirror # 130E58”, manufactured by Toray Industries, Inc., thickness 1)
30 μm), the coating liquid for forming the cushion-made intermediate layer was applied, the coating layer was dried, and then the coating liquid for the image receiving layer was applied and dried. The thickness of the cushion layer after drying is about 20μ
m, the coating amount was adjusted such that the layer thickness of the image receiving layer was about 2 μm. The produced transfer material is wound up in a roll form,
After storing at room temperature for one week, it was used for image recording with the following laser beam.

-Formation of Transfer Image- The transfer material (25 cm.times. 3
5 cm) and vacuum-adsorbed. Then 30c
The thermal transfer sheet C (cyan) cut into mx 40 cm
Were overlapped so as to evenly protrude from the material to be transferred, and squeezed by a squeeze roller, and were adhered and laminated so that air was sucked into the section holes. The degree of pressure reduction when the section hole is closed is -150 with respect to 1 atm.
mmHg (≒ 81.13 kPa). The drum is rotated, and a semiconductor laser beam having a wavelength of 808 nm is condensed from the outside onto the surface of the laminated body on the drum so as to form a 7 μm spot on the surface of the photothermal conversion layer. The laser image (image) was recorded on the laminate while moving in the direction perpendicular to the scanning direction) (sub-scanning). Laser irradiation conditions are as follows. The laser beam used in this embodiment was a multi-beam two-dimensional laser beam consisting of five parallel lines in the main scanning direction and three parallel lines in the sub-scanning direction. Laser power 110 mW Drum rotation speed 500 rpm Sub-scanning pitch 6.35 μm Ambient temperature and humidity 23 ° C. 50% The laminated body on which the laser recording was completed was removed from the drum, and the thermal transfer sheet C was peeled off from the material to be transferred by hand. Only the light irradiation area of the image forming layer of the sheet C was transferred from the thermal transfer sheet C to the material to be transferred, and it was confirmed that an image was formed.

-Retransfer to Final Transfer Material- The transfer material on which an image has been transferred from the thermal transfer sheet C and the final transfer material (recording paper; Tokishi Art 135g; manufactured by Mitsubishi Paper Mills) are overlaid. In addition, Laminator CA-680T
Retransfer was performed using III (manufactured by Fuji Photo Film Co., Ltd.), the support of the material to be transferred was removed, and a final image was obtained on the final material to be transferred (recording paper).

Example 2 In the composition of the coating solution for the photothermal conversion layer, instead of adding 14.7 parts of compound 1 and 14.7 parts of polyimide resin, 14.7 parts of compound 2 was added.
A thermal transfer sheet C was prepared in the same manner as in Example 1 except that 14.7 parts of a polyimide resin and polyimide resin were added. Then, in the same manner as in Example 1, a transfer image was formed using the thermal transfer sheet C and the material to be transferred, and retransferred to a final transfer body (recording paper) to obtain a final image.

[0123]

Embedded image

Example 3 In the composition of the coating solution for the photothermal conversion layer, instead of adding 14.7 parts of the compound 1 and 14.7 parts of the polyimide resin, 14.7 parts of the compound 3 was added.
A thermal transfer sheet C was prepared in the same manner as in Example 1 except that 14.7 parts of a polyimide resin and polyimide resin were added. Then, in the same manner as in Example 1, a transfer image was formed using the thermal transfer sheet C and the material to be transferred, and retransferred to a final transfer body (recording paper) to obtain a final image.

[0125]

Embedded image

(Comparative Example 1) In the composition of the coating solution for the photothermal conversion layer, 14.7 parts of compound 1 and polyimide resin 1
Instead of adding 4.7 parts, a polyimide resin was added to 29.
A comparative thermal transfer sheet C was prepared in the same manner as in Example 1 except that 3 parts were added. Then, as in the first embodiment,
A transfer image was formed using the comparative thermal transfer sheet C and the material to be transferred, and retransferred to the final material to be transferred (recording paper) to obtain a final image.

Comparative Example 2 Instead of adding 14.7 parts of Compound 1 and 14.7 parts of polyimide resin, 14.7 parts of polymethyl methacrylate and 14.7 parts of polyimide were added to the composition of the coating solution for the photothermal conversion layer. A thermal transfer sheet C was prepared in the same manner as in Example 1 except that 14.7 parts of the resin was added. Then, in the same manner as in Example 1, a transfer image was formed using the thermal transfer sheet C and the material to be transferred, and retransferred to a final transfer body (recording paper) to obtain a final image.

<Evaluation of Recorded Image> The light resistance and transferability of the final images obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were evaluated according to the following criteria. Table 1 shows the evaluation results.

1) Evaluation of Light Resistance The obtained final image was exposed to light under a fluorescent lamp of 1000 Lux for 48 hours, and the hue before and after the exposure was measured, and the difference (color difference) was obtained. The hue is X-ri
Using te938 (manufactured by X-rite), L ^* .a ^*.
The b ^* value was measured. It should be noted that in the L ^* · a ^* · b ^* values, L
^* Is a value representing lightness, and a ^* and b ^* represent attributes of color perception composed of hue and saturation, and are values called color coordinates. The evaluation was performed according to the following criteria.色 The color difference is 1 or less (no change in hue) ○ The color difference is 1 to 2 (there is little change in the hue) Δ The color difference is 2 to 4 (the change in the hue is slight) × The color difference is 4 or more ( There is considerable hue variation)

2) Evaluation of Transferability The transferability of the obtained final image was visually evaluated according to the following criteria. ◎ No transfer failure ○ Slight floating on transfer part △ Slight untransferred part × Untransferred part XX × Untransferred part

[0131]

[Table 1]

As shown in Table 1, in the light-to-heat conversion layer of the thermal transfer sheet C, the compound 1 to the anionic polymer
In Examples 1 to 3 containing No. 3, the change in hue in the final image was small, the light resistance was excellent, and the transferability was excellent as compared with Comparative Examples 1 and 2 not containing the anionic polymer. It became clear that there was.

[0133]

According to the present invention, the transfer of the light-to-heat conversion dye such as the infrared absorbing dye contained in the light-to-heat conversion layer to the image forming layer and the hue of the recorded image due to the decomposition of the dye after laser recording are performed. It is possible to provide a thermal transfer sheet that can prevent deterioration in image quality such as fluctuations and is excellent in light resistance and transferability.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H111 AA01 AA12 AA26 AA35 BA03 BA07 BA53 BA55 BA61 BA71 BA76

Claims (6)

[Claims] 1. A thermal transfer sheet comprising, on a support, a light-to-heat conversion layer containing at least an infrared absorbing dye and an image forming layer in this order, wherein the light-to-heat converting layer is capable of forming a salt with the infrared absorbing dye. A thermal transfer sheet comprising at least one kind of anionic polymer. 2. The thermal transfer sheet according to claim 1, wherein the photothermal conversion layer contains a salt of an infrared absorbing dye and an anionic polymer. 3. An anionic polymer comprising a sulfonate,
3. The composition according to claim 1, wherein at least one of a carboxylate and a phosphate is contained as a repeating unit.
4. The thermal transfer sheet according to 1. 4. The thermal transfer sheet according to claim 1, wherein the anionic polymer is soluble in an organic solvent. 5. The thermal transfer sheet according to claim 1, wherein the infrared absorbing dye is a cationic dye having an absorption coefficient of 100,000 or more at 700 to 900 nm. 6. An image forming layer comprising a coloring material and a softening point of 40 to 40.
Each containing 20 to 80% by weight of an amorphous organic high molecular polymer in the range of 150 ° C. and having a thickness of 0.2
3. The method according to claim 1, wherein the distance is in the range of 1.5 to 1.5 μm.
6. The thermal transfer sheet according to any one of 5.