JP2000351282A - Thermal transfer sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat transfer sheet which is free from any adverse effect by a coating liquid applied to a layer to be formed on a light/heat conversion layer showing high heat resistance and humidity resistance and further, is less susceptible of a change over time and is hardly unstable in performance with an ability to produce a good-quality transfer image almost without a fog. SOLUTION: This heat transfer sheet has a light/heat conversion layer and an image forming layer formed on a support. In this case, a binder for the light/heat conversion layer is an organic solvent dissoluble polymer having 220-400 deg.C glass transition temperature and 420 deg.C or higher 5% weight reduction temperature. An intermediate layer is formed between the support and the photothermal conversion layer.

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 using a laser beam. In particular, the present invention relates to a color proof (DDCP: direct digital
Or a thermal transfer sheet that can be used in an image forming method useful for creating a mask image.

[0002]

2. Description of the Related Art In the field of graphic arts, printing of a printing plate is performed using a set of color separation films prepared from a color original using a lithographic film. In order to check for errors in the color separation process and the necessity of color correction, a color proof is created from the color separation film. A color proof is required to have high resolution which enables high reproducibility of a halftone image and high performance such as high process stability. In addition, in order to obtain a color proof similar to an actual printed matter, as a material used for a color proof, a material used for an actual printed matter, for example, a printing paper as a base material and a pigment as a coloring material are used. Is preferred. Also,
As a method for producing a color proof, there is a high demand for a dry method using no developer.

As a dry color proofing method, a recording system for directly creating a color proof from digital signals has been developed with the recent widespread use of digitization systems in the pre-printing process (prepress field). In such an electronic system, it is particularly necessary to create a color proof of high image quality, and it is generally necessary to reproduce a halftone image of 150 lines / inch or more. In order to record a high-quality proof from a digital signal, it is necessary to use a laser beam which can be modulated by the digital signal and can narrow down the recording light as a recording head. For this reason, it is necessary to develop a recording material that exhibits high recording sensitivity to laser light and high resolution that enables high-definition halftone dots to be reproduced.

As a recording material used in a transfer image forming method using a laser beam, a photothermal conversion layer which absorbs a laser beam and generates heat, a wax having a heat-fusible pigment, a binder and the like are provided on a support. Heat-melt transfer sheet having an image forming layer dispersed in the components
No. 8045). In the image forming method using these recording materials, 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 image receiving sheet stacked on the transfer sheet. Then, a transfer image is formed on the image receiving sheet.

Japanese Patent Application Laid-Open No. 6-219052 discloses that a light-to-heat conversion layer containing a light-to-heat conversion substance, a very thin (0.03-0.3 μm) heat-peeling layer, and a coloring material are provided on a support. An image forming layer including the image forming layer is provided in this order, the bonding force between the image forming layer and the light-to-heat conversion layer that are bonded by the interposition of the thermal peeling layer, using a thermal transfer sheet that is reduced by irradiation with laser light, An image forming method for forming a high-definition image on an image receiving sheet laminated on the thermal transfer sheet is described. This image forming method utilizes so-called "ablation". Specifically, the thermal peeling layer is partially decomposed and vaporized in a region irradiated with laser light, so that the image forming layer and the photothermal This utilizes the phenomenon that the bonding strength between the conversion layer and the image forming layer is weakened and the image forming layer in that region is transferred to the image receiving sheet laminated thereon.

In these image forming methods, printing paper having an image receiving layer (adhesive layer) attached thereto can be used as an image receiving sheet material, and multicolor images can be easily formed by transferring images of different colors onto the image receiving sheet one after another. In particular, an image forming method using ablation has an advantage that a high-definition image can be easily obtained, and has a color proof (DDCP: direct digital color proof) or a high color proof. This is useful for creating a fine mask image.

[0007] In the thermal transfer sheet used in these image forming methods, the heat converted by the absorption of laser light causes the binder of the light-to-heat conversion layer to have a glass transition temperature or higher, and promotes diffusion of the light-to-heat conversion substance or its decomposed product, and Transfer to the body, part of the binder polymer is thermally decomposed, thermal destruction of the layer occurs, and the photothermal conversion material in the layer is transferred to the image receiving member under the pressure of a pyrolysis gas or the like. Fog) may occur. For this reason, a polymer having good heat resistance has been required as a binder for the light-to-heat conversion layer.

[0008]

A thermal transfer sheet having improved heat resistance of the light-to-heat conversion layer is disclosed in JP-A-8-26791.
No. 6, the main binder used for the light-to-heat conversion layer, T
A recording medium is disclosed in which a temperature at which a weight loss rate is 50% under a cooling rate of 10 ° C./min in a nitrogen gas flow by thermal decomposition measurement by a GA method is 360 ° C. or higher. .

However, the water-soluble polymer specifically used has a large water absorption, and the heat in the light-to-heat conversion layer evaporates due to heat during laser irradiation, and the pressure or the like tends to promote the transfer of the heat transfer layer. As a result, there has been a problem that the temperature and humidity changes in the recording sensitivity become extremely large and the heat resistance is insufficient.

In Japanese Patent Application Laid-Open No. Hei 9-11646, as a binder for the light-to-heat conversion layer, the above-mentioned Japanese Patent Application Laid-Open No. Hei 8-267916 is used.
The use of a polyamic acid satisfying the requirements of the above item is disclosed. The binder used in Japanese Patent Application Laid-Open No. Hei 9-11646 is superior to the binder used in Japanese Patent Application Laid-Open No. Hei 8-267916 in terms of environmental stability, application with a general-purpose solvent, and the like. When recording an image with a high-power laser, the heat resistance is still insufficient.

[0011] Further, in Japanese Patent Application Laid-Open No. 2-252579,
Examples describe a thermal transfer sheet having a light-to-heat conversion layer for laser sublimation thermal transfer by applying a coating solution containing a polyimide precursor and carbon black, drying the coating layer, and performing heat treatment. This thermal transfer sheet requires long-term high-temperature heat treatment to form polyimide from the polyimide precursor, which increases the manufacturing cost and easily induces thermal decomposition of the dye that is a photothermal conversion material during heat treatment. Was a big problem.

The present inventor has been researching a binder suitable for a light-to-heat conversion layer, and has found that a light-to-heat conversion layer formed using a specific organic solvent-soluble polymer such as a polyimide resin having excellent heat resistance. The layer is not dissolved by the coating solution of the layer formed thereon (image forming layer or heat-sensitive release layer), and the performance of the light-to-heat conversion layer due to the migration of the dye and the occurrence of fogging do not occur. And high heat resistance, so that it was possible to prevent transfer inhibition.

However, when a solvent for dissolving such a binder is directly applied to a support such as polyethylene terephthalate, the support often swells, and as a result, the solvent tends to remain on the support and easily change with time. , Performance tends to be unstable.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide a thermal transfer sheet which has improved heat resistance of a light-to-heat conversion material and has little change in fog and image quality over time.

[0015]

According to the present invention, there is provided a heat transfer sheet having a light-to-heat conversion layer and an image forming layer provided on a support, wherein the binder of the light-to-heat conversion layer has a glass transition temperature of 2 or less.
An organic solvent (excluding a halogen-containing organic solvent) soluble polymer having a 5% weight loss temperature of 420 ° C. or more at 20 to 400 ° C., and an intermediate layer provided between the support and the photothermal conversion layer. This is a characteristic thermal transfer sheet.

It is preferable that the intermediate layer has a cushioning property. In addition, a polyimide resin can be used as the organic solvent-soluble polymer.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Materials for forming the thermal transfer sheet of the present invention will be described.

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. Preferred examples of the support material include synthetic resin materials such as polyethylene terephthalate, polyethylene-2,6-naphthalate, polycarbonate, polyethylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, and styrene-acrylonitrile copolymer. . Above all, biaxially stretched polyethylene terephthalate is preferable in consideration of mechanical strength and dimensional stability against heat. When the thermal transfer sheet of the present invention is used for producing a color proof using laser recording,
The support of the thermal transfer sheet is preferably formed of a transparent synthetic resin material that transmits laser light.

The support of the thermal transfer sheet may be subjected to a surface activation treatment and / or the provision of one or more undercoat layers in order to improve the adhesion to the intermediate layer provided thereon. preferable. Examples of the surface activation treatment include a glow discharge treatment and a corona discharge treatment. The material of the undercoat layer preferably has high adhesiveness to both surfaces of the support and the intermediate layer, has low thermal conductivity, and is excellent in heat resistance. Examples of such a material for the undercoat layer include styrene, styrene-butadiene copolymer, and gelatin.
The thickness of the entire undercoat layer is usually 0.01 to 2 μm. Further, on the surface of the thermal transfer sheet opposite to the side on which the light-to-heat conversion layer is provided, various functional layers such as an anti-reflection layer or surface treatment can be applied as necessary.

In the present invention, an intermediate layer is provided on a support.
The intermediate layer is formed of a material that is impermeable or difficult to pass through the coating solvent for the light-to-heat conversion layer. Specific materials used for the intermediate layer include polyethylene, polypropylene, ethylene-vinyl acetate resin, ethylene-containing polymers such as ethylene-acrylic resin, water-soluble resins such as polyvinyl alcohol, gelatin, acrylic resin, and the like. -2- Preference is given to high boiling solvents such as pyrrolidone and DMF. The material used for the intermediate layer need not be completely dissolved in the solvent, and may swell.

The thickness of the intermediate layer is preferably from 0.05 to 20 μm, more preferably from 0.2 to 10 μm.

A cushion layer can be provided on the intermediate layer, if necessary. The cushion layer is a layer that is easily deformed when subjected to an external force. By providing the cushion layer, the adhesiveness between the thermal transfer sheet and the image receiving sheet is improved, and the image quality is improved. In order to provide cushioning, a material having a low elastic modulus, a material having rubber elasticity, or a thermoplastic resin which is easily softened by heating may be used.

The elastic modulus is 10 to 500 kg at room temperature.
f / cm 2 or less, particularly preferably 30 to 150 kgf /
It is preferably in the range of cm 2. In addition, in order to allow a foreign substance such as rubber to penetrate, the penetration (25 ° C., 100 g, 5 seconds) specified by JIS K2530 is preferably 10 or more. The glass transition temperature of the cushion layer is 80 ° C. or lower, preferably 25 ° C. or lower. It is also possible to suitably add a plasticizer to the polymer binder in order to adjust these physical properties, for example, Tg.

Specific materials used as a binder for the cushion layer include rubbers such as urethane rubber, butadiene rubber, nitrile rubber, acrylic rubber, and natural rubber, as well as polyethylene, polypropylene, polyester, and styrene-butadiene copolymer. Copolymer, ethylene-vinyl acetate copolymer, ethylene-acryl copolymer, vinyl chloride-vinyl acetate copolymer, vinylidene chloride resin, vinyl chloride resin containing a plasticizer, polyamide resin, phenol resin and the like.

The thickness of the cushion layer varies depending on the resin used and other conditions, but is usually 3 to 100 μm, preferably 10 to 52 μm.

Incidentally, the intermediate layer may also serve as the cushion layer. In that case, in terms of solvent barrier properties, polyethylene, polypropylene, ethylene-vinyl acetate resin, ethylene-
Polyolefin-containing polymers such as acrylic resins are preferred.

The light-to-heat conversion material used for the light-to-heat conversion layer formed on the support is generally a dye (eg, a pigment) capable of absorbing laser light. Examples of the black pigments such as carbon black, phthalocyanine, pigments of macrocyclic compounds having absorption in the near infrared region such as naphthalocyanine,
Organic dyes such as organic dyes (cyanine dyes such as indolenine dyes, anthraquinone dyes, azulene dyes, and phthalocyanine dyes) used as laser absorbing materials for high-density laser recording such as optical disks, and organic metals such as dithiol nickel complexes Compound dyes can be mentioned. In order to increase the recording sensitivity, the light-to-heat conversion layer is preferably as thin as possible. Therefore, it is desirable to use an infrared absorbing dye such as a cyanine dye or a phthalocyanine dye having a large absorption coefficient in the laser light wavelength region. In addition, as the laser light absorbing material of the photothermal conversion layer,
Inorganic materials such as metal materials can also be used. The metal material is used as particles (for example, blackened silver). The optical density at the laser absorption wavelength of the photothermal conversion substance is preferably from 0.1 to 2.0, and more preferably from 0.3 to 1.2. When the optical density is smaller than 0.1, the sensitivity of the thermal transfer sheet is lowered, and when the optical density is higher than 2.0, the cost is increased.

Examples of the organic solvent-soluble polymer used for the light-heat conversion layer include organic solvent-soluble polyimide resins, polyamides, and polysulfones. In addition,
In the present invention, the organic solvent soluble in an organic solvent does not include a halogen-containing organic solvent. Among them, a polyimide resin having the following structure can be used as the organic solvent-soluble polyimide resin.

[0029]

Embedded image

[In the formulas (I) and (II), Ar1 represents an aromatic group represented by the formulas (1) to (3);
Shows an integer of 100]

[0031]

Embedded image

[0032]

Embedded image

In the formulas (III) and (IV), Ar2
Represents an aromatic group represented by (4) to (7), and n represents 10
Represents an integer of ~ 100)

[0034]

Embedded image

[0035]

Embedded image

[In the formulas (V) to (VII), n and m are 10
Shows an integer of ~ 100. In the formula (VI), the ratio of n: m is 6: 4 to 9: 1. Further, PISO from Celanese is also preferably used.

The use of a polyimide resin as a binder has been conventionally known, but the conventional polyimide resin has poor solvent solubility, and high temperature conditions such as a melt extrusion method are essential for film formation. Since the polyimide resin used in the present invention has solvent solubility, it is possible to provide a layer containing the photothermal conversion material without decomposing the photothermal conversion material which is easily decomposed at the time of raising the temperature.

The glass transition temperature of these organic solvent-soluble polymers must be 220 ° C. or more and 400 ° C. or less, and preferably 250 ° C. or more. If the glass transition temperature is lower than 220 ° C., fog increases, and 400 ° C.
If it is higher, the solubility decreases. Further, the thermal decomposition temperature of the polymer soluble in the organic solvent (temperature at which the weight is reduced by 5% in an air stream at a temperature rising rate of 10 ° C./min by the TGA method) must be 420 ° C. or more, and 475 ° C. It is preferable that it is above.

The light-to-heat conversion layer can be provided by preparing a coating solution in which the above-mentioned light-to-heat conversion substance and an organic solvent-soluble polymer are dissolved, coating the solution on the support, and drying. Examples of the organic solvent for dissolving the organic solvent-soluble polymer include 1,4-dioxane and 1,3
-Dioxolane, dimethyl acetate, N-methyl-2
-Pyrrolidone, dimethylsulfoxide, dimethylformamide, γ-butyrolactone and the like. Coating and drying can be performed by using ordinary coating and drying methods. Drying is usually performed at a temperature of 300 ° C. or less. Preferably, the drying temperature is 200 ° C. or less, and when polyethylene terephthalate is used as the support, the drying temperature is 8 ° C.
The temperature is more preferably in the range of 0 to 150 ° C.

The light-to-heat conversion layer formed as described above has a solid content weight ratio of the dye (dye or pigment) and the organic solvent-soluble polymer as the binder of 1:20 to 2: 1 (dye: binder). And particularly preferably in the range of 1:10 to 2: 1. If the amount of the binder is too small, the cohesive force of the light-to-heat conversion layer decreases, and when the formed image is transferred to the image receiving sheet, the light-to-heat conversion layer is easily transferred together, causing color mixing of the image. On the other hand, if the amount of the binder is too large, the thickness of the light-to-heat conversion layer becomes large in order to achieve a constant light absorptance, and the sensitivity tends to decrease. The layer thickness of the light-to-heat conversion layer is 0.03-0.
It is preferably in the range of 8 μm, more preferably,
It is 0.05 to 0.3 μm. The light-to-heat conversion layer is 70
It preferably has a maximum absorbance (optical density) in the range of 0.1 to 2.0 (more preferably, in the range of 0.2 to 1.2) in the wavelength range of 0 to 2000 nm.

On the light-to-heat conversion layer of the thermal transfer sheet of the present invention, gas is generated by the action of heat generated in the light-to-heat conversion layer, or adhered water or the like is released, whereby the light-to-heat conversion layer and the image forming layer are separated. A heat-sensitive release layer containing a heat-sensitive material that reduces the bonding strength between the layers can be provided. Examples of such heat-sensitive materials include compounds (polymers and low-molecular compounds) that decompose or degrade due to heat to generate gas, and compounds that absorb or adsorb a considerable amount of easily vaporizable gas such as moisture (polymer Further, a low molecular compound) can be used. These may be used in combination.

Examples of the polymer which decomposes or degrades by heat to generate a gas include a self-oxidizing polymer such as nitrocellulose, chlorinated polyolefin, chlorinated rubber, polyvinyl chloride, polyvinyl chloride, and polyvinylidene chloride. Such volatile compounds as halogen-containing polymers, acrylic polymers such as polyisobutyl methacrylate to which volatile compounds such as water are adsorbed, cellulose esters such as ethyl cellulose to which volatile compounds such as water are adsorbed, and volatile compounds such as water. Natural polymer compounds such as adsorbed gelatin can be exemplified. Examples of the low molecular weight compound which decomposes or degrades by heat to generate a gas include a compound which generates a gas upon exothermic decomposition such as a diazo compound or an azide compound. In addition, it is preferable that the heat-sensitive material is decomposed or deteriorated by heat at 280 ° C. or lower, and particularly,
It preferably occurs at a temperature of 30 ° C. or lower.

When a low-molecular compound is used as the heat-sensitive material of the heat-sensitive release layer, it is desirable to combine it with a binder. As the binder, the above-mentioned polymer which itself decomposes or degrades by heat to generate a gas, or a general polymer binder having no such properties can be used. When a heat-sensitive low-molecular compound and a binder are used in combination, the weight ratio of the former to the latter is 0.02: 1.
３3: 1, preferably 0.05: 1 to 2: 1.
Is more preferable. The heat-sensitive release layer desirably covers the light-to-heat conversion layer over substantially the entire surface thereof, and has a thickness of generally 0.03 to 1 μm.
It is preferably in the range of 0.5 to 0.5 μm.

In the case of a thermal transfer sheet having a structure in which an intermediate layer, a light-to-heat conversion layer, a heat-sensitive peeling layer, and an image forming layer are laminated on a support in this order, the heat-sensitive peeling layer is formed by heat transferred from the light-to-heat conversion layer. Decomposes and degrades to generate gas. Then, due to the decomposition or generation of gas, the heat-sensitive peeling layer partially disappears, or cohesive failure occurs in the heat-sensitive peeling layer, and the bonding force between the light-heat conversion layer and the image forming layer decreases. For this reason, depending on the behavior of the heat-sensitive release layer, a part of the heat-sensitive release layer may adhere to the image forming layer and appear on the surface of a finally formed image, which may cause color mixing of the image. Therefore, even when such transfer of the heat-sensitive release layer occurs, the heat-sensitive release layer is hardly colored (that is, high in visible light) so that color mixture does not appear visually in the formed image. Showing transparency) is desirable. Specifically, the light absorption of the heat-sensitive release layer is 50% or less, and preferably 10% or less, with respect to visible light.

Instead of providing a separate heat-sensitive release layer, a heat-sensitive material may be added to the light-to-heat conversion layer so that the light-to-heat conversion layer also functions as the heat-sensitive release layer.

In the thermal transfer sheet of the present invention, an image forming layer is provided on the light-to-heat conversion layer or the heat-sensitive release layer. The image forming layer contains a pigment and an amorphous organic high molecular polymer.

Pigments are generally classified into organic pigments and inorganic pigments. The former is particularly excellent in the transparency of the coating film, and the latter is generally excellent in the hiding property. When the thermal transfer sheet of the present invention is used for printing color proofing, an organic pigment that matches or has a similar color tone to yellow, magenta, cyan, and black generally used for printing inks is preferably used. In addition, a metal powder, a fluorescent pigment, or the like may be used. Examples of preferably used pigments include azo pigments, phthalocyanine pigments, anthraquinone pigments, dioxazine pigments, quinacridone pigments, isoindolinone pigments, and nitro pigments. The following is a description of representative pigments classified by hue. 1) Yellow pigment Hansa Yellow G, Hansa Yellow 5G, Hansa Yellow 10G, Hansa Yellow A, Pigment Yellow L,
Permanent Yellow NCG, Permanent Yellow F
GL, permanent yellow HR. 2) red pigment permanent red 4R, permanent red F2R,
Permanent Red FRL, Lake Red C, Lake Red D, Pigment Scarlet 3B, Bordeaux 5B,
Alizarin Lake, Rhodamine Lake B. 3) Blue pigments Phthalocyanine blue, Victoria blue lake, Fast sky blue. 4) Black pigment carbon black.

Examples of the amorphous organic high molecular polymer having a softening point of 40 ° C. to 150 ° C. contained in the image forming layer of the thermal transfer sheet of the present invention include, for example, butyral resin, polyamide resin, polyethyleneimine resin and sulfonamide resin. Styrene, such as polyester polyol resin, petroleum resin, styrene, vinyl toluene, α-methyl styrene, 2-methyl styrene, chloro styrene, vinyl benzoic acid, sodium vinyl benzene sulfonate, amino styrene, and derivatives thereof, Copolymers and copolymers, methyl methacrylate, ethyl methacrylate, butyl methacrylate, methacrylic acid esters such as hydroxyethyl methacrylate and methacrylic acid, methyl acrylate,
Acrylic esters such as ethyl acrylate, butyl acrylate, α-ethylhexyl acrylate, and dienes such as acrylic acid, butadiene, isoprene, acrylonitrile, vinyl ethers, maleic acid and maleic esters, maleic anhydride, cinnamic acid, and vinyl chloride Or a copolymer of vinyl monomers such as vinyl acetate alone or with other monomers. These resins can be used as a mixture of two or more kinds.

In the present invention, the image forming layer contains 30 to 7 pigments.
0% by weight, preferably 40 to 60% by weight, and 70 to 30% by weight of the amorphous organic high molecular polymer, preferably 60 to 40% by weight.
% By weight.

When a multicolor image is formed by repeatedly superimposing a large number of image layers (image forming layers on which images have been formed) on the same image receiving sheet, the image forming layers must be formed in order to enhance the adhesion between the images. Preferably contains a plasticizer. Examples of such plasticizers are dibutyl phthalate, di-n-phthalate.
Octyl, di (2-ethylhexyl) phthalate, dinonyl phthalate, dilauryl phthalate, butyl lauryl phthalate, butyl benzyl phthalate and the like; di (2-ethylhexyl) adipate, di (2-ethylhexyl) sebacate Aliphatic dibasic acid esters such as -ethylhexyl), phosphoric acid triesters such as tricresyl phosphate and tri (2-ethylhexyl) phosphate, polyol polyesters such as polyethylene glycol esters, and epoxy compounds such as epoxy fatty acid esters. Can be In addition to the general plasticizers described above, polyethylene glycol dimethacrylate, 1,2,4-butanetriol trimethacrylate, trimethylolethane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, Acrylic esters such as pentaerythritol-polyacrylate are also suitably used depending on the type of binder used. Incidentally, two or more plasticizers may be used in combination.

In the image forming layer, the weight ratio of the total amount of the pigment and the amorphous organic high molecular polymer to the plasticizer is generally 100: 1 to 100: 20, preferably 1: 1.
It is used so as to be in the range of 00: 2 to 100: 10. In the image forming layer, a surfactant, a thickener, and the like are further added, if necessary, in addition to the above components. The layer thickness (dry layer thickness) of the image forming layer is 0.2 to 1.5 μm, preferably 0.3 to 1.0 μm.

To prevent damage, a protective cover film (eg, polyethylene terephthalate sheet, polyethylene sheet, etc.) may be laminated on the surface of the image forming layer.

The image receiving sheet has a configuration having at least an image receiving layer on a support. If necessary, a cushion layer, a release layer, or a layer serving as both may be provided between the support and the image receiving layer. It is also preferable to have a back layer on the surface opposite to the image receiving layer from the viewpoint of transportability and the like.
It is also preferable to provide an antistatic layer separately from these layers, or to add an antistatic agent to each of the above layers.

As the support, a sheet-like base material such as a plastic sheet, paper, metal sheet, glass sheet or the like is usually used. As an example of the plastic sheet, a sheet of polyethylene terephthalate, polyethylene naphthalate, polyethylene, polycarbonate, polyvinyl chloride, polyvinylidene chloride, polystyrene or the like is used, and a polyethylene terephthalate sheet is particularly preferable. As the paper, printing paper, coated paper, or the like can be used. The thickness of the base material of the image receiving sheet is usually 10
４００400 μm, preferably 25-200 μm. Further, as the support, a white material having bubbles inside is preferable in terms of cushioning property, image visibility, and the like,
Particularly, a foamed polyester support is most preferable in terms of mechanical properties. The surface of the substrate may be subjected to a surface treatment such as a corona discharge treatment or a glow discharge treatment in order to enhance the adhesion to the image receiving layer.

The image receiving layer is a layer formed mainly of an organic polymer binder. The binder is preferably a thermoplastic resin, examples of which include acrylic acid, methacrylic acid, acrylic acid esters, homopolymers of acrylic monomers such as methacrylic acid esters and copolymers thereof, methylcellulose, ethylcellulose, cellulose acetate Cellulosic polymers such as polystyrene, polyvinylpyrrolidone, polyvinyl butyral, polyvinyl alcohol, homopolymers of vinyl monomers such as polyvinyl chloride and copolymers thereof, condensation polymers such as polyesters and polyamides, butadiene Rubber-based polymers such as styrene copolymers. The binder of the image receiving layer is provided with a glass transition temperature (T.sub.T) in order to obtain a proper adhesive strength with the image forming layer.
g) is preferably lower than 90 ° C. For this purpose, it is also possible to add a plasticizer to the image receiving layer. The binder polymer of the image receiving layer preferably has a Tg of 30 ° C. or higher in order to prevent blocking between sheets. As the binder polymer of the image receiving layer, it is particularly preferable to use the same or similar polymer as the binder polymer of the thermal transfer layer in terms of improving the adhesion to the thermal transfer layer during laser recording and improving sensitivity and image strength. .

The thickness of the image receiving layer is 0.3 to 7 μm, preferably 0.7 to 4 μm. When the thickness is 0.3 μm or less, the film strength is insufficient at the time of retransfer to the printing paper, and the film is easily broken. If it is too thick, the gloss of the image after retransfer of the paper increases, and the closeness to the printed matter decreases.

The cushion layer is a layer that is easily deformed when stress is applied to the image receiving layer, and has an effect of improving the adhesion between the image forming layer and the image receiving layer during laser thermal transfer and improving the image quality. Further, at the time of recording, even if foreign matter is mixed between the thermal transfer sheet and the image receiving sheet, the gap between the image receiving layer and the thermal transfer layer is reduced due to the deforming action of the cushion layer. Have. Further, when an image is formed by transferring an image once, and then transferring the image to a separately prepared printing paper, the image receiving surface is deformed according to the uneven surface of the paper, so that the transferability of the image receiving layer is improved, and By lowering the gloss of the printed matter, the effect of improving the closeness to the printed matter can be provided.

In order to provide cushioning, a material having a low elastic modulus, a material having rubber elasticity, or a thermoplastic resin which is easily softened by heating may be used.

The elastic modulus is 10 to 500 kg at room temperature.
f / cm 2 or less, particularly preferably 30 to 150 kgf /
It is preferably in the range of cm 2. In addition, in order to allow a foreign substance such as rubber to penetrate, the penetration (25 ° C., 100 g, 5 seconds) specified by JIS K2530 is preferably 10 or more. The glass transition temperature of the cushion layer is 80 ° C. or lower, preferably 25 ° C. or lower. It is also possible to suitably add a plasticizer to the polymer binder in order to adjust these physical properties, for example, Tg.

Specific materials used as the binder for the cushion layer include rubbers such as urethane rubber, butadiene rubber, nitrile rubber, acrylic rubber, and natural rubber, as well as polyethylene, polypropylene, polyester, and styrene-butadiene copolymer. Copolymer, ethylene-vinyl acetate copolymer, ethylene-acryl copolymer, vinyl chloride-vinyl acetate copolymer, vinylidene chloride resin, vinyl chloride resin containing a plasticizer, polyamide resin, phenol resin and the like.

The thickness of the cushion layer varies depending on the resin used and other conditions, but is usually 3 to 100 μm, preferably 10 to 50 μm.

The image receiving layer and the cushion layer need to be adhered to each other up to the stage of laser recording, but are preferably provided so as to be peelable in order to transfer the image to the printing paper. In order to facilitate peeling, it is preferable to provide a peeling layer having a thickness of about 0.1 to 2 μm between the cushion layer and the image receiving layer. This release layer preferably has a function as a barrier for a coating solvent at the time of coating the image receiving layer.

Although the above-described structure of the image receiving sheet has been described as an example in which a support, a cushion layer, and an image receiving layer are provided, depending on the case, a support / cushionable image receiving layer in which the image receiving layer also serves as a cushion layer, or a support may be used. / Undercoat layer / cushionable image receiving layer. Also in this case, it is preferable that the cushioning image-receiving layer is provided so as to be releasable so that it can be re-transferred to the printing paper. In this case, the image after retransfer to the printing paper becomes an image having excellent gloss. The thickness of the cushion layer also serving as the image receiving layer is 5 to 100 μm, preferably 1 to 100 μm.
0 to 40 μm.

In the case where an image is once formed on the image receiving layer and then retransferred to printing paper or the like, it is preferable that at least one of the image receiving layers is formed of a photocurable material. Examples of the composition of such a photocurable material include: a) a photopolymerizable monomer comprising at least one of a polyfunctional vinyl or vinylidene compound capable of forming a photopolymer by addition polymerization;
Examples of the combination include b) an organic polymer, c) a photopolymerization initiator, and, if necessary, additives such as a thermal polymerization inhibitor. As the polyfunctional vinyl monomer, unsaturated esters of polyols, particularly esters of acrylic acid or methacrylic acid (eg, ethylene glycol diacrylate, pentaerythritol tetraacrylate) are used.

Examples of the organic polymer include the above-mentioned polymer for forming an image receiving layer. As the photopolymerization initiator, a general photoradical polymerization initiator such as benzophenone and Michler's ketone is used in a ratio of 0.1 to 20% by weight in the layer.

Various additives can be added to each of the above layers as needed. For example, the addition of an antistatic agent such as a surfactant and tin oxide fine particles and a matting agent such as silicon oxide and PMMA particles to the back layer of the image receiving support improves transportability in a recording apparatus. It is preferred in that respect.
These additives can be added not only to the back layer but also to the image receiving layer and other layers as necessary. Although the type of the additive cannot be unconditionally specified depending on the purpose, for example, in the case of a matting agent, particles having an average particle size of 0.5 to 10 μm can be added in the layer at about 0.5 to 80%.
As the antistatic agent, the surface resistance of the layer is 23 ° C., 50% R
The surfactant may be appropriately selected from various surfactants and conductive agents so that the resistance is 1012 Ω or less, more preferably 109 Ω or less under the condition of H.

The laminate of the thermal transfer sheet and the image receiving sheet of the present invention can be formed by various methods. For example, it can be easily obtained by stacking the image forming layer side of the thermal transfer sheet and the image receiving side (image receiving layer side) of the image receiving sheet and passing them through a pressure and heating roller. The heating temperature in this case is preferably 160 ° C. or lower, or 130 ° C.

As another method for obtaining a laminate, a vacuum contact method is also suitably used. First, the image receiving sheet is wound on a drum provided with a suction hole for evacuation, and then a thermal transfer sheet slightly larger than the image receiving sheet is vacuum adhered to the image receiving sheet while uniformly extruding air with a squeeze roller. is there.

As another method, there is a method in which an image receiving sheet is mechanically attached to a metal drum while being pulled, and a thermal transfer sheet is similarly attached to the metal drum while being mechanically pulled and adhered. Among these methods, the vacuum adhesion method is particularly preferable because temperature control of a heat roller or the like is not required and lamination can be performed quickly and uniformly.

Next, an image forming method using the thermal transfer sheet of the present invention will be described. In the image forming method using the thermal transfer sheet of the present invention, an image forming laminate in which an image receiving sheet is laminated on the surface of the image forming layer of the thermal transfer sheet is prepared, and the surface of the laminate is irradiated with laser light in an image-wise manner. Then, the image receiving sheet and the thermal transfer sheet are separated from each other to obtain an image receiving sheet on which the laser light irradiated area of the image forming layer has been transferred. The joining of the thermal transfer sheet and the image receiving sheet may be performed immediately before the laser beam irradiation operation. This laser beam irradiation operation is usually performed on the image receiving sheet side of the image forming laminate.
The surface of a recording drum (a rotary drum having a vacuum forming mechanism inside and a large number of minute openings on the surface) is brought into close contact with the surface of a recording drum by vacuum evacuation, and in that state, the laser beam is irradiated from the outside, that is, the thermal transfer sheet side. It is performed by The laser beam is scanned so as to reciprocate in the width direction of the drum, and the drum is rotated at a constant angular velocity during the irradiation operation.

The laser light may be a gas laser light such as an argon ion laser light, a helium neon laser light, a helium cadmium laser light, a solid laser light such as a YAG laser light, a semiconductor laser, a dye laser light, or an excimer laser light. Laser light is used. Alternatively, light obtained by converting these laser lights to half the wavelength through a second harmonic element can be used. In the image forming method using the thermal transfer sheet of the present invention, it is preferable to use a semiconductor laser in consideration of output power, ease of modulation, and the like. Further, in the image forming method using the thermal transfer sheet of the present invention, it is preferable that the laser beam is irradiated under conditions such that the beam diameter on the light-to-heat conversion layer is in the range of 5 to 50 μm (particularly 6 to 30 μm), The scanning speed is preferably 1 m / sec or more (particularly 3 m / sec or more).

The image forming method using the thermal transfer sheet of the present invention can be used for producing a black mask or for forming a monochromatic image, but can also be advantageously used for forming a multi-color image. In order to form a multicolor image by the image forming method using the thermal transfer sheet of the present invention, for example, three types (three colors) or three types of image forming laminates each having an image forming layer containing a colorant of a different color are independently Four types (four colors)
To manufacture. Next, the first-color heat transfer sheet and the image receiving sheet are laminated, a laser beam irradiation is performed according to a digital signal based on the color-separated image, and the subsequent image recording transfer sheet and the image receiving sheet are peeled off. Is repeated for the second and subsequent colors to form a multicolor image on the image receiving sheet. Further, if necessary, a method can be used in which the multicolor image is re-transferred onto the main paper by superposing the image receiving sheet on which the multicolor image has been formed on the printing paper, heating and pressurizing through a laminator, and peeling off.

[0073]

EXAMPLES [Example 1] <Preparation of thermal transfer sheet> 1) Application of undercoat layer and intermediate layer on support surface Polyethylene terephthalate (PET) film support (center line average surface texture Ra = 0.04 μm) Is coated with a styrene-butadiene copolymer to a dry film thickness of 0.5 μm, and the coating layer is dried (the coating solvent is toluene).
Then, an undercoat layer for improving the adhesion between the intermediate layer and the support was provided. The coating at this time was performed for 1 minute using a rotary coating machine (wheeler), and the drying was performed for 2 minutes in an oven at 100 ° C. Next, a coating solution (water-ethanol mixed solvent) of polyvinyl alcohol (Povar type 205, manufactured by Kuraray Co., Ltd.) was applied on the undercoat layer in the same manner as for the undercoat layer, and the coated layer was dried to a thickness of 1 μm. An intermediate layer (light-heat conversion layer solvent barrier layer) was obtained. 2) Preparation and application of coating solution for forming photothermal conversion layer The following components were mixed while stirring with a stirrer to prepare a coating solution for forming a photothermal conversion layer. (Coating liquid composition) parts by weight Infrared absorbing dye (NK-2014, manufactured by Nippon Kogaku Dyeing Co., Ltd.) 10 Binder (Licacoat SN-20, manufactured by Shin Nippon Rika Co., Ltd.) 200 Glass transition temperature 295 ° C., 5% weight loss (Temperature: 510 ° C.) N-methyl-2-pyrrolidone 2000 surfactant (Megafac F-177, manufactured by Dainippon Ink and Chemicals, Inc.) Prior to preparing the coating solution, a polyimide resin (Ricacoat SN- 20, a 20% by weight solution of N-methyl-2-pyrrolidone) was observed, the transparency was good, and after the polyimide resin was filtered under pressure with a 10 μm filter, no unfiltered material remained on the filter. It was confirmed that the resin was sufficiently dissolved in N-methyl-2-pyrrolidone. (Formation of a light-to-heat conversion layer on the surface of the intermediate layer) After the above-mentioned coating solution was applied on the surface of the intermediate layer using a rotary coating machine, the coated product was dried in an oven at 120 ° C for 2 minutes. A light-to-heat conversion layer was formed on the support. The light-to-heat conversion layer obtained is
At a wavelength of 700 to 1000 nm, there was an absorption maximum near 830 nm, and the absorbance (optical density; OD) was measured to be OD = 1.0. When the cross section of the light-to-heat conversion layer was observed with a scanning electron microscope, the film thickness was found to be an average of 0.
It was 3 μm. 3) Preparation and application of coating solution for yellow image formation Paint shaker (Toyo Seiki Co., Ltd.)
After 2 hours dispersion treatment, the glass beads are removed,
A yellow pigment dispersion mother liquor was prepared. (Pigment dispersion mother liquor composition) parts by weight polyvinyl butyral (manufactured by Denki Kagaku Kogyo Co., Ltd., 9.78 butyral # 2000-L, Piccat softening point 57 ° C.) Color material (yellow pigment (C.I.PY-14)) 17.8 Dispersing aid (Solsperse S-20000, manufactured by ICI Co., Ltd.) 0.79 n-propyl alcohol 110 Glass beads 100 The following components are mixed while stirring with a stirrer, and coated for forming a yellow image forming layer. Here, the parts by weight of the pigment-dispersed mother liquor indicated the values after the removal of the glass beads (the same applies hereinafter) (Composition of the coating solution) The parts by weight of the pigment-dispersed mother liquor (after the removal of the glass beads) 180 polyvinyl butyral (Denki 5.12 butyral # 2000-L, manufactured by Denki Kagaku Kogyo KK) Stearamide 3.15 Nonionic surfactant ( Mistat 1100. 0.52 Sanyo Kasei Co., Ltd. Rosin (KE-311, Arakawa Chemical Co., Ltd.) 3.38 Surfactant (MegaFac F-176P, 1.12 Dainippon Ink and Chemicals, Inc.) N-Propyl alcohol 1130 Methyl ethyl ketone 285 (Formation of yellow image forming layer on light-to-heat conversion layer surface) The above-mentioned coating solution was applied to the surface of the above-mentioned light-to-heat conversion layer for 1 minute using a wheeler. After drying in an oven at 2 ° C. for 2 minutes, a yellow image forming layer (47% by weight of pigment, 36.2% by weight of polyvinyl butyral) was formed on the light-to-heat conversion layer. It was OD = 0.71 as measured by TD-904 (Blue filter). , On average 0.4μ
m.

Through the above steps, a thermal transfer sheet was formed on the support, in which an undercoat layer, an intermediate layer, a light-to-heat conversion layer, and a yellow image forming layer were provided in this order. <Preparation of Image Receiving Sheet> A coating solution for a cushion intermediate layer and an image receiving layer having the following compositions was prepared. (Composition of Cushioning Intermediate Layer Coating Solution) Parts by weight Vinyl chloride-vinyl acetate copolymer (manufactured by Nissin Chemical Co., Ltd., 20 MPR-TSL) Plasticizer (adipic acid-based polyester, 10 trade name Paraplex G40, CP. HALL.COMPANY Co., Ltd.) Surfactant (Megafac F-177, 0.5 Dainippon Ink & Chemicals, Inc. Antistatic agent (SAT-5 Super (IC), 0.3 Nippon Pure Chemical Co., Ltd.) )) Solvent Methyl ethyl ketone 60 Toluene 10 N, N-dimethylformamide 3 (Coating solution composition for image receiving layer) Parts by weight Polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd.) 3.0 ESREC B BL-SH Surfactant (mega) FAK-177, 0.1 Dainippon Ink and Chemicals, Inc. Antistatic agent (Sunstat 2012A, Sanyo Chemical Industries, Ltd.) 0.7 n-propyl alcohol 20 methanol 20 1-methoxy-2-propanol 50 On a white PET support [Lumilar E-68L, 135 μm in thickness] by using a narrow coater. The layer liquid was applied, the intermediate layer was dried, then the image receiving layer liquid was applied, and the image receiving layer was dried. The thickness of the intermediate layer after drying is about 20
The coating amount was adjusted so that the thickness was about 2 μm and the thickness of the image receiving layer was about 2 μm. Example 2 Polyethylene was cast and laminated on the same polyester film as the thermal transfer sheet support used in Example 1 by a melt extrusion method, and a 10 μm-thick intermediate layer was laminated. Next, after performing glow discharge treatment on the surface of the polyethylene layer in an oxygen atmosphere, a light-to-heat conversion layer and a yellow image forming layer were provided in the same manner as in Example 1 to obtain a thermal transfer sheet. [Example 3] A coating solution for a cushioning intermediate layer having the following composition was prepared and applied on the same polyester film as the thermal transfer sheet support used in Example 1, and the applied layer was dried.
An intermediate layer having a thickness of 6 μm was obtained.

(Composition of Coating Solution for Intermediate Layer) Parts by weight Ethylene-vinyl acetate resin 10 (EV-40Y, manufactured by Mitsui-Dupont Polychemicals Co., Ltd.) Toluene 50 Methyl ethyl ketone 20 Next, photothermal conversion was performed in the same manner as in Example 1. Layer and a yellow image forming layer were provided to obtain a thermal transfer sheet. Example 4 <Preparation of Thermal Transfer Sheet> A thermal transfer sheet was obtained in the same manner as in Example 3 except that the following light-to-heat conversion layer was provided on the intermediate layer of Example 3. 1) Preparation of coating solution for forming photothermal conversion layer The following components were mixed while stirring with a stirrer to prepare a coating solution for forming a photothermal conversion layer. (Coating liquid composition) parts by weight Carbon black dispersion mother liquor 20 N-methyl-2-pyrrolidone 60 surfactant (Megafac F-177, 0.05 manufactured by Dainippon Ink and Chemicals, Inc.) Here, the carbon black dispersion mother liquor is Liquid of the following composition,
Obtained by dispersing for 2 hours in a paint shaker. (Carbon black dispersed mother liquor composition) parts by weight Binder (Ricacoat SN-20, manufactured by Shin Nippon Rika Co., Ltd.) 60 Carbon black (MA-100, manufactured by Mitsubishi Chemical Corporation) 10 Dispersing aid (SOLSPERS S-20000, ICI 0.7 N-methyl-2-pyrrolidone 60 glass beads 100 2) Application of light-to-heat conversion layer In the same manner as in Example 1, the above-mentioned light-to-heat conversion layer coating solution was applied on a PET support, Dry the coating layer to a thickness of 0.3
A light-to-heat conversion layer of μm was obtained. Comparative Example 1 A thermal transfer sheet was obtained in the same manner as in Example 1, except that the photothermal conversion layer was provided directly on the PET support without providing the undercoat layer and the intermediate layer. Comparative Example 2 An intermediate layer, a light-to-heat conversion layer, and a yellow light-to-heat conversion layer were formed on a support in the same manner as in Example 3 except that a light-to-heat conversion layer was formed using a coating liquid for forming a light-to-heat conversion layer having the following composition. A thermal transfer sheet having the image forming layers laminated in this order was obtained. (Coating liquid composition) Parts by weight Infrared absorbing dye (NK-2014, manufactured by Nippon Kogaku Dye Co., Ltd.) 10 Binder (polyamic acid PAA-A, Tg 200 ° C., 160 5% weight loss temperature 400 ° C., Mitsui Toatsu Co., Ltd.) Methyl ethyl ketone 1000 1-methoxy-2-propanol 1000 surfactant (Megafac H-177, manufactured by Dainippon Ink and Chemicals, Inc.) The above polyamic acid PAA-A (aromatic tetracarboxylic dianhydride) Obtained by the reaction of
Is a 25% by weight solution of N, N-dimethylacetamide. After coating and drying, this is a high temperature
It is a polyimide precursor that becomes polyimide by heat treatment for more than one minute. Comparative Example 3 <Preparation of Thermal Transfer Sheet> A thermal transfer sheet was obtained in the same manner as in Example 4, except that the light-to-heat conversion layer was prepared by the following method. 1) Preparation of coating solution for forming photothermal conversion layer The following components were mixed while stirring with a stirrer to prepare a coating solution for forming a photothermal conversion layer. (Coating liquid composition) Parts by weight Carbon black dispersion mother liquor 15 Polyvinyl alcohol (Poval, type 217C, 15% weight loss decomposition temperature 280 ° C, manufactured by Kuraray Co., Ltd.) Ion exchange water 50 Isopropyl alcohol 9 Here, the carbon black dispersion mother liquor is Liquid of the following composition,
Obtained by dispersing for 2 hours in a paint shaker. (Composition of carbon black dispersion mother liquor) parts by weight carbon black (Mitsubishi carbon black MA-100, 10 manufactured by Mitsubishi Chemical Corporation) Dispersing aid (manufactured by Johnson Polymer Co., Ltd., 3% aqueous solution of 3 John Krill J-62) ion Exchanged water 80 Isopropyl alcohol 20 Glass beads 100 2) Application of light-to-heat conversion layer In the same manner as in Example 1, the above-mentioned light-to-heat conversion layer coating solution was applied to a PET support, and the coating layer was dried to obtain a film thickness of 0. 4
A light-to-heat conversion layer of μm was obtained. <Evaluation of Laser Thermal Transfer Characteristics> 1) Evaluation of Recording Sensitivity The above-mentioned image receiving sheet (25 cm ×) was placed on a rotating drum having a diameter of 25 cm provided with a vacuum suction hole having a diameter of 1 mm (one surface density in an area of 3 cm × 3 cm). 35 cm) was wound and adsorbed. Next, a thermal transfer sheet of 30 cm × 40 cm was overlapped so as to evenly protrude from the image receiving sheet, and squeezed by a squeeze roller, and both were brought into close contact with each other so that air was sucked into a suction hole and laminated. The degree of pressure reduction in a state where the suction hole was closed was -150 mmHg with respect to 1 atm.

The above-mentioned drum is rotated, and a semiconductor laser beam having a wavelength of 830 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. While moving in the direction perpendicular to the main scanning direction (sub-scanning), the laminated body was irradiated with laser to record an image (image). The laser irradiation conditions are as follows. Laser power 110 mW Main scanning speed 4 m / sec Sub-scanning pitch 20 μm Ambient temperature and humidity 25 ° C., 50% RH The laminate on which the laser image was recorded was removed from the drum, and the image receiving sheet and the thermal transfer sheet were peeled off by hand. It was confirmed that only the laser irradiation portion of the image (image line) forming layer was transferred from the thermal transfer sheet to the image receiving sheet. Observation of the transferred image with an optical microscope revealed that the image was recorded linearly. The recording line width was measured, and the strength was obtained from the following equation. Table 1 shows the results. Sensitivity = (laser power P) / (line width d × line speed v) 2) Evaluation of image quality A halftone dot (5%, 50%, 95%) image is formed by laser recording, and the image is subjected to an optical microscope (100 times magnification). ), And the image quality was evaluated from the following viewpoints. ◎ There is no micro transfer unevenness (drops, gaps) and good halftone dot shape. ○ Although there is some transfer slippage, the level is acceptable for practical use. △ Transfer drop is noticeable. × Transfer drop is very remarkable and halftone dot shape is poor. 3) Evaluation of fog A solid image was recorded in the same manner as above except that the sub-scanning pitch was changed to 10 μm so that the beam lines were overlapped, and the presence or absence of fog was visually evaluated according to the following criteria. 〇 Good △ Inconspicuous, but with transfer × Fog is noticeable. XX Fog very remarkable Table 1 shows the results of the above evaluations after the material was left in a room temperature environment for 2 days or 1 month after preparation.

[0077]

[Table 1]

[0078]

According to the thermal transfer sheet of the present invention, an intermediate layer is provided, and the light-to-heat conversion layer is formed of a specific binder. Therefore, an image having low fog and excellent image quality can be provided.

Claims (3)

[Claims] 1. A thermal transfer sheet having a light-to-heat conversion layer and an image forming layer provided on a support, wherein the binder of the light-to-heat conversion layer has a glass transition temperature of 220 to 400 ° C. and a 5% weight loss temperature of 420 ° C. or more. A thermal transfer sheet comprising an organic solvent-soluble polymer, wherein an intermediate layer is provided between the support and the photothermal conversion layer. 2. The thermal transfer sheet according to claim 1, wherein the intermediate layer has a cushioning property. 3. The thermal transfer sheet according to claim 1, wherein the organic solvent-soluble polymer is a polyimide resin.