JP2002274028A - Thermal transfer sheet and multicolor image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal transfer sheet, which is highly sensitive and in the image forming layer of which an image with an excellent image quality can be formed under the condition being applied to a multicolor image forming method utilizing abrasion, and the multicolor image forming method employing the thermal transfer sheet. SOLUTION: A photothermal conversion layer and an image forming layer and, when necessary, in addition, a heat insulating layer is provided on one side of a support, on the opposite side of which an antistatic layer is provided. In the thermal transfer sheet, the ratio (I/I0 ) of the non-diffuse transmittance (I) to the total light transmittance (I0 ) of a layer consisting of the antistatic layer and the support and, in addition, the heat insulating layer as the case may be is 0.8 or more within the range of light wavelength of 400 to 900 nm and 0.7 or more under the condition that the heat insulating layer is added and the multicolor image forming method employing the thermal transfer sheet is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a thermal transfer sheet which can be used in a multicolor image forming method using a laser beam, and an image forming method using the image receiving material.

[0002]

2. Description of the Related Art In the field of graphic arts, a printing plate is printed using a set of color separation films prepared from a color original by 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 made 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 the 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 strong demand for a dry method using no developer.

As a dry-type color proofing method, with the recent widespread use of digitization systems in the pre-printing process (prepress field), a recording system for directly producing a color proof from digital signals has been developed. The purpose of such an electronic system is to produce a color proof having a high image quality, and generally reproduces a halftone image of 150 lines / inch or more. In order to record a proof of high image quality from a digital signal, a laser beam that can be modulated by the digital signal and that can narrow down the recording light is used 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 to generate heat, a wax having a pigment which is heat-meltable, a binder, etc. are provided on a support. Heat-melt transfer sheet having an image forming layer dispersed in the components
No. 58045) is known. 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 laminated 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. There is disclosed a thermal transfer sheet provided with an image forming layer in this order. In this thermal transfer sheet, by being irradiated with laser light, the bonding force between the image forming layer and the light-to-heat conversion layer that are bonded by the interposition of the thermal release layer is reduced, and the thermal transfer sheet is laminated on the thermal transfer sheet. A high-definition image is formed on the image receiving sheet. The image forming method using the thermal transfer sheet utilizes so-called "ablation", and specifically, in a region irradiated with laser light, the heat release layer partially decomposes and evaporates. This utilizes a phenomenon in which the bonding force between the image forming layer and the light-to-heat conversion layer is weakened, and the image forming layer in that region is transferred to the image receiving sheet laminated thereon.

According to these image forming methods, a 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 formed by transferring images of different colors onto the image receiving sheet one after another. The image forming method has an advantage that it can be easily obtained. In particular, an image forming method utilizing ablation has an advantage that a high-definition image can be easily obtained, and is color proof (DDCP: direct digital color proof) Alternatively, it is useful for producing a high-definition mask image.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to
It is an object of the present invention to provide a thermal transfer sheet that can form a high-sensitivity, high-quality image on an image forming layer when applied to a multicolor image forming method using ablation and is excellent in integration. Another object of the present invention is to provide a multicolor image forming method using the above-described thermal transfer sheet having excellent performance.

[0008]

According to the present invention, a thermal transfer sheet and a multicolor image forming method having the following constitutions are provided, and the above object of the present invention is achieved. 1. A heat transfer sheet in which a light-to-heat conversion layer and an image forming layer are provided in this order on one side of a support, and an antistatic layer is provided on the opposite side, wherein a layer comprising an antistatic layer and a support total light transmission ratio of the non-diffuse transmittance to _{(I O) (I) (} I / I O) is in a range of light wavelengths 400 to 900 nm, a thermal transfer sheet wherein a is 0.8 or more. 2. A heat transfer sheet in which a light-to-heat conversion layer and an image forming layer are provided in this order on one surface of a support, and an antistatic layer is provided on the other surface, wherein a heat insulating layer is provided between the support and the light-to-heat conversion layer. And the ratio (I / I _O ) of the non-diffuse transmittance (I) to the total light transmittance (I _O ) of the layer including the heat insulating layer, the antistatic layer, and the support is 400 to 900 nm.
A thermal transfer sheet having a light wavelength of 0.7 or more in the range of the light wavelength. 3. The surface specific resistance on the image forming layer side measured under an environment of a temperature of 23 ° C. and a relative humidity of 50% is 1 × 10 ¹⁵ Ω / sq or less, and the surface specific resistance on the antistatic layer side is 1 × 10 ⁹ Ω / sq.
3. The thermal transfer sheet as described in 1 or 2, wherein the thermal transfer sheet has a sq or less. 4. The image forming layer has a thickness of 0.1 to 1.5 μm, preferably 0.1 to 1.5 μm.
An amorphous organic high molecular polymer having a thickness of 2 to 1.0 μm, a pigment and a softening point of 40 to 150 ° C.
The thermal transfer sheet according to any one of the above items 1 to 3, wherein the thermal transfer sheet is contained in a mass ratio of 0 to 70/30 (pigment / polymer). 5. A photothermal conversion type image forming material comprising a combination of the thermal transfer sheet according to any one of the above items 1 to 4 and an image receiving sheet having at least an image receiving layer on a support. 6. Using an image receiving sheet having an image receiving layer on a support and four types of thermal transfer sheets of yellow, magenta, cyan, and black having at least a light-to-heat conversion layer and an image forming layer on the support, Forming an image on the image receiving layer of the image receiving layer by irradiating a laser beam and irradiating a laser beam on the image forming layer and the image receiving layer of the image receiving sheet; A method for forming a color image, wherein the thermal transfer sheet comprises:
5. A multicolor image forming method, which is the thermal transfer sheet according to any one of items 1 to 4.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The thermal transfer sheet of the present invention can be used in a multicolor image forming method described later. At that time, the thermal transfer sheet overlaps the image forming layer and the image receiving layer of the image receiving sheet facing each other, irradiates the laser light, and transfers the laser light irradiation area of the image forming layer onto the image receiving layer of the image receiving sheet. The image is recorded. The image recorded on the image receiving sheet is retransferred to the actual paper.

The thermal transfer sheet according to the first aspect of the present invention is provided with a light-to-heat conversion layer and an image forming layer on one surface of a support in this order, and an antistatic layer on the opposite surface.
Total light transmittance (I _O ) of layer composed of antistatic layer and support
Ratio (I / I _O ) of the non-diffuse transmittance (I) to
In the light wavelength range of 00 to 900 nm, the thermal transfer sheet of the second aspect of the present invention, which is 0.8 or more, preferably 0.9 or more, is provided with a heat insulating layer between the support and the light-to-heat conversion layer. The ratio of the non-diffused transmittance (I) to the total light transmittance (I _O ) of the layer comprising the heat insulating layer, the antistatic layer and the support (I / I _O ) is 400 to 900 nm. 0.7 or more, preferably 0.8
Is over

The above-mentioned non-diffusion transmittance is measured by a spectroscope UV-240 manufactured by Shimadzu Corporation.

As described above, the thermal transfer sheet of the present invention can be used in the multicolor image forming method of the present invention in combination with an image receiving sheet. Hereinafter, the multicolor image forming method of the present invention will be described in detail, and among them, the thermal transfer sheet will be described in more detail.

The multicolor image forming method according to the present invention realizes a thermal transfer image by sharp halftone dots, and also realizes transfer of the paper and B2
This is effective and suitable for a system capable of recording a size (515 mm × 728 mm, B2 size is 543 mm × 765 mm). This thermal transfer image is 2400-2
A halftone image corresponding to the number of print lines can be obtained at a resolution of 540 dpi. Since each halftone dot has almost no bleeding or chipping and a very sharp shape, a high range of halftone dots from highlight to shadow can be formed clearly. As a result, it is possible to output high-quality halftone dots at the same resolution as the imagesetter or CTP setter.
It is possible to reproduce halftone dots and gradation with good print similarity.

Further, since the thermal transfer image has a sharp halftone dot shape, the halftone dot corresponding to the laser beam can be faithfully reproduced, and the recording characteristics have a very small dependency on environmental temperature and humidity. Under the above conditions, stable reproducibility of both hue and density can be obtained. This thermal transfer image is formed using the coloring pigment used in the printing ink, and has high repetition
A CMS (color management system) can be realized. In addition, this thermal transfer image can be made to substantially match the hue of Japan color, SWOP color and the like, that is, the hue of the printed matter, and the appearance of the color when the light source such as a fluorescent lamp or an incandescent lamp changes is the same as that of the printed matter. Can be shown.

Further, since the thermal transfer image has a sharp dot shape, fine lines of fine characters can be clearly reproduced.
The heat generated by the laser beam is transmitted to the transfer interface without diffusing in the plane direction, and the image forming layer is sharply broken at the interface between the heated portion and the non-heated portion. For this purpose, the thinning of the light-to-heat conversion layer in the thermal transfer sheet and the mechanical properties of the image forming layer are controlled. By the way, in the simulation, it is estimated that the light-to-heat conversion layer instantaneously reaches about 700 ° C., and if the film is thin, deformation or destruction is likely to occur. When the deformation / destruction occurs, the light-to-heat conversion layer is transferred to the image receiving sheet together with the transfer layer, or the transferred image becomes non-uniform. On the other hand, in order to obtain a predetermined temperature, the photothermal conversion substance must be present in a high concentration in the film, which causes problems such as precipitation of a dye and migration to an adjacent layer. For this reason, it is preferable to reduce the thickness of the light-to-heat conversion layer to about 0.5 μm or less by selecting an infrared-absorbing dye having excellent light-to-heat conversion properties and a heat-resistant binder such as polyimide.

Generally, when the light-to-heat conversion layer is deformed or the image forming layer itself is deformed due to high heat, the image forming layer transferred to the image receiving layer has a thickness unevenness corresponding to the sub-scanning pattern of the laser beam. And the resulting image becomes non-uniform and the apparent transfer density decreases. This tendency is more remarkable as the thickness of the image forming layer is smaller. On the other hand, when the thickness of the image forming layer is large, the sharpness of the dots is impaired and the sensitivity is lowered. In order to balance these conflicting performances, it is preferable to improve transfer unevenness by adding a low melting point substance such as a wax to the image forming layer. Also, by adding inorganic fine particles instead of the binder, the layer thickness is appropriately increased, so that the image forming layer is sharply broken at the interface between the heated part and the unheated part, and the dot sharpness and sensitivity are maintained. In addition, transfer unevenness can be improved.

Generally, low-melting substances such as waxes are
It tends to seep or crystallize on the surface of the image forming layer,
In some cases, there is a problem in image quality or stability of the thermal transfer sheet over time. In order to address this problem, it is preferable to use a low melting point substance having a small difference in Sp value from the polymer in the image forming layer, to increase the compatibility with the polymer and to separate the low melting point substance from the image forming layer. Can be prevented. It is also preferable to mix several kinds of low-melting substances having different structures so as to make them eutectic to prevent crystallization. As a result, an image having a sharp dot shape and less unevenness can be obtained. In general, when the coating layer of the thermal transfer sheet absorbs moisture, the mechanical and thermal properties of the layer change, and the recording environment becomes dependent on humidity. In order to reduce the temperature / humidity dependency, it is preferable that the dye / binder system of the light-to-heat conversion layer and the binder system of the image forming layer are organic solvent systems. Further, it is preferable to select polyvinyl butyral as a binder for the image receiving layer and to introduce a polymer hydrophobizing technique in order to reduce the water absorption. Examples of the polymer hydrophobization technique include reacting a hydroxyl group with a hydrophobic group and crosslinking two or more hydroxyl groups with a hardener as described in JP-A-8-238858.

In general, the image forming layer also receives heat of about 500 ° C. or more during printing by laser exposure, and some pigments conventionally used are thermally decomposed. This can be prevented by adopting it in the image forming layer. Then, when the infrared absorbing dye is transferred from the light-to-heat conversion layer to the image forming layer due to high heat at the time of printing, the infrared absorbing dye having a strong coercive force as described above is used to prevent the hue from being changed. It is preferable to design the light-to-heat conversion layer with a combination of binders. Generally, in high-speed printing, energy is insufficient, and a gap corresponding to the interval between laser sub-scans is generated. As described above, increasing the concentration of the dye in the light-to-heat conversion layer and reducing the thickness of the light-to-heat conversion layer / image forming layer can increase the efficiency of heat generation / transmission. Further, it is preferable to add a low-melting substance to the image forming layer for the purpose of increasing the effect of slightly flowing the image forming layer upon heating and filling the gap and the adhesiveness to the image receiving layer. Further, in order to increase the adhesiveness between the image receiving layer and the image forming layer and to sufficiently impart the strength of the transferred image, it is preferable to employ, for example, the same polyvinyl butyral as the image forming layer as the binder of the image receiving layer.

The image receiving sheet and the thermal transfer sheet are preferably held on a drum by vacuum contact. This vacuum contact is important because the image transfer behavior is very sensitive to the clearance between the image receiving layer surface of the image receiving sheet and the image forming layer surface of the transfer sheet since an image is formed by controlling the adhesive force between the two sheets. If the clearance between the materials is widened due to foreign matter such as dust, image defects and image transfer unevenness occur. In order to prevent such image defects and image transfer unevenness, it is preferable to form uniform unevenness on the thermal transfer sheet to improve the air flow and obtain a uniform clearance.

As a method for forming irregularities on the thermal transfer sheet, there are generally post-treatments such as embossing, and addition of a matting agent to the coating layer. However, addition of a matting agent is preferable for simplifying the manufacturing process and stabilizing the material over time. . The matting agent needs to be larger than the thickness of the coating layer, and if the matting agent is added to the image forming layer, a problem occurs in that the image of the portion where the matting agent is present will be lost. It is preferable to add it to the conversion layer, whereby the image forming layer itself has a substantially uniform thickness, and a defect-free image can be obtained on the image receiving sheet.

In order to reliably reproduce the sharp dots as described above, a high-precision design is also required on the recording device side. The basic configuration is the same as that of the conventional laser thermal transfer recording apparatus. This configuration is a so-called heat mode outer drum recording system in which a recording head having a plurality of high-power lasers irradiates a laser onto a thermal transfer sheet and an image receiving sheet fixed on a drum to perform recording. Among them, the following embodiments are preferred configurations. The supply of the image receiving sheet and the thermal transfer sheet is a fully automatic roll supply. The image receiving sheet and the thermal transfer sheet are fixed to the recording drum by vacuum suction. A number of vacuum suction holes are formed on the recording drum, and the inside of the drum is depressurized by a blower, a decompression pump, or the like, so that the sheet is adsorbed on the drum.
The size of the thermal transfer sheet is made larger than that of the image receiving sheet because the thermal transfer sheet is further attracted from above the image receiving sheet. The air between the thermal transfer sheet and the image receiving sheet, which has the greatest effect on the recording performance, is sucked from the area of the thermal transfer sheet only outside the image receiving sheet.

In the present apparatus, it is assumed that a large number of sheets having a large area of B2 size can be stacked and stacked on a discharge table.
For this purpose, a method is employed in which air is blown out between the two sheets to float the sheet discharged later. FIG. 2 shows a configuration example of the present apparatus. A sequence in the present apparatus as described above will be described. 1) The sub-scanning axis of the recording head 2 of the recording apparatus 1 returns to the origin by the sub-scanning rail 3, and the main scanning rotation axis of the recording drum 4 and the thermal transfer sheet loading unit 5 return to the origin. 2) The image receiving sheet roll 6 is unwound by the transport roller 7, and the leading end of the image receiving sheet is vacuum-suctioned and fixed on the recording drum 4 via a suction hole provided in the recording drum. 3) The squeeze roller 8 descends onto the recording drum 4 and stops while the image receiving sheet is further conveyed by a specified amount by rotation of the drum while holding down the image receiving sheet, and is cut to a specified length by the cutter 9. 4) The recording drum 4 further makes one revolution, and the loading of the image receiving sheet is completed. 5) Next, in the same sequence as the image receiving sheet, the first color-black thermal transfer sheet K is fed out from the thermal transfer sheet roll 10K, cut, and loaded. 6) Next, the recording drum 4 starts rotating at a high speed, the recording head 2 on the sub-scanning rail 3 starts to move, and when the recording head reaches a recording start position, the recording head 2 irradiates the recording laser onto the recording drum 4 according to the recording image signal. Is done. The irradiation ends at the recording end position, and the sub-scanning rail operation and the drum rotation stop. Return the recording head on the sub-scanning rail to the origin. 7) With the image receiving sheet left on the recording drum, only the thermal transfer sheet K is peeled off. Therefore, the front end of the thermal transfer sheet K is hooked with a nail and pulled out in the discharge direction, and is discarded from the discard port 32 to the discard box 35. 8) Repeat steps 5) to 7) for the remaining three colors. The recording order is black, followed by cyan, magenta, and yellow. That is, the second color-cyan thermal transfer sheet C is sequentially from the thermal transfer sheet roll 10C, the third color-magenta thermal transfer sheet M is from the thermal transfer sheet roll 10M, and the fourth color-yellow thermal transfer sheet Y is sequentially from the thermal transfer sheet roll 10Y. It is paid out. This is the opposite of the general printing order, because the color order on the paper is reversed by the paper transfer in a later step. 9) When the four colors are completed, the recorded image receiving sheet is finally discharged to the discharge table 31. The method of peeling off from the drum is the same as that of the thermal transfer sheet of 7), but unlike the thermal transfer sheet, it is not discarded. When the sheet is discharged to the discharge table, air 34 is blown out from below the discharge port 33 to enable stacking of a plurality of sheets.

A transport roller 7 at either a supply site or a transport site of the thermal transfer sheet roll and the image receiving sheet roll.
It is preferable to use an adhesive roll having an adhesive material disposed on the surface.

By providing the adhesive roll, the surfaces of the thermal transfer sheet and the image receiving sheet can be cleaned.

Examples of the adhesive material provided on the surface of the adhesive roll include ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, polyolefin resin, polybutadiene resin, styrene-butadiene copolymer (SB
R), styrene-ethylene-butene-styrene copolymer (SEBS), acrylonitrile-butadiene copolymer (NBR), polyisoprene resin (IR), styrene-
Examples include isoprene copolymer (SIS), acrylate copolymer, polyester resin, polyurethane resin, acrylic resin, butyl rubber, and polynorbornene.

The surface of the pressure-sensitive adhesive roll can be cleaned by making contact with the surface of the thermal transfer sheet and the image receiving sheet, and the contact pressure is not particularly limited as long as it is in contact.

The absolute value of the difference between the surface roughness Rz of the surface of the image forming layer of the thermal transfer sheet and the surface roughness Rz of the surface of the backside layer is 3.0 or less. It is preferable that the absolute value of the difference in the surface roughness Rz of the surface of the back surface layer is 3.0 or less. With such a configuration, image defects can be prevented in combination with the above-described cleaning means, transport jams can be eliminated, and dot gain stability can be improved.

In this specification, the surface roughness Rz is defined as J
A ten-point average surface roughness corresponding to Rz (maximum height) of IS, and the average surface of a portion extracted by a reference area from a curved surface of roughness is used as a reference surface to determine the highest to fifth peaks. The distance between the average value of the altitude and the average value of the depth of the valley bottom from the deepest to the fifth is input and converted. For the measurement, a stylus type three-dimensional roughness meter (Surfcom 570) manufactured by Tokyo Seimitsu Co., Ltd.
A-3DF). The measurement direction was the vertical direction, the cutoff value was 0.08 mm, and the measurement area was 0.6 mm × 0.4.
mm, the feed pitch is 0.005 mm, and the measurement speed is 0.12 mm / s.

The absolute value of the difference between the surface roughness Rz of the surface of the image forming layer of the thermal transfer sheet and the surface roughness Rz of the surface of the back layer is 1.0 or less, and the surface roughness of the surface of the image receiving layer of the image receiving sheet. It is preferable that the absolute value of the difference between the surface roughness Rz and the surface roughness Rz of the back surface layer be 1.0 or less from the viewpoint of further improving the above effect.

In another embodiment, the surface roughness of the surface of the image forming layer of the thermal transfer sheet and the surface of the back layer thereof and / or the surface roughness Rz of the front and back surfaces of the image receiving sheet is preferably 2 to 30 μm. With such a configuration, it is possible to prevent image defects in combination with the above-described cleaning means, eliminate conveyance jams, and further improve dot gain stability.

The glossiness of the image forming layer of the thermal transfer sheet is preferably from 80 to 99.

The glossiness greatly depends on the smoothness of the surface of the image forming layer, and can affect the uniformity of the thickness of the image forming layer. Higher glossiness is more suitable as an image forming layer for application to high-definition images, but high smoothness results in higher resistance during transport, and both are in a trade-off relationship.
When the glossiness is in the range of 80 to 99, both can be compatible and the balance can be maintained.

The Vickers hardness Hv of the adhesive material used for the adhesive roll is 50 kg / mm ² (# 490M
Pa) or less is preferable because dust as foreign matter can be sufficiently removed and image defects can be suppressed.

The Vickers hardness means that the facing angle is 13
This is a hardness measured by applying a static load to a 6-degree square pyramidal diamond indenter, and the Vickers hardness Hv is obtained by the following equation.

Hardness Hv = 1.854 P / d ² (kg / m
^{m 2) ≒ 18.1692d 2 (MPa} ) wherein P: load size (kg), d: the recesses of a square diagonal length (mm)

[0036] In the present invention, elastic modulus at 20 ° C. of the material having tackiness for use in the above adhesive roll is not more than 200kg / cm ² (≒ 19.6MPa) is, like the above foreign substance It is preferable because certain dust can be sufficiently removed and image defects can be suppressed. Next, an outline of a mechanism for forming a multicolor image by thin-film thermal transfer using a laser will be described with reference to FIG. Thermal transfer sheet 10
An image forming laminate 30 in which the image receiving sheet 20 is laminated on the surface of the image forming layer 16 containing the black (K), cyan (C), magenta (M) or yellow (Y) pigment is prepared. The thermal transfer sheet 10 includes a support 12, a light-to-heat conversion layer 14 on the support 12, and an image forming layer 1 on the support 12.
6, the image receiving sheet 20 has a support 22 and an image receiving layer 24 thereon, and is laminated on the surface of the image forming layer 16 of the thermal transfer sheet 10 so that the image receiving layer 24 comes into contact with the image receiving layer 24. (FIG. 1 (a)). Thermal transfer sheet 10 of the laminate 30
When the laser light is irradiated in a time-series manner from the support 12 side in an image-like manner, the laser light-irradiated area of the photothermal conversion layer 14 of the thermal transfer sheet 10 generates heat, and the adhesion to the image forming layer 16 decreases ( FIG. 1 (b). Thereafter, when the image receiving sheet 20 and the thermal transfer sheet 10 are peeled off, the laser light irradiated area 16 ′ of the image forming layer 16 is transferred onto the image receiving layer 24 of the image receiving sheet 20 (FIG. 1C).

In the formation of a multicolor image, the laser beam used for light irradiation is preferably a multi-beam beam, and more preferably a multi-beam two-dimensional array. The multi-beam two-dimensional arrangement means that when recording by laser irradiation, a plurality of laser beams are used, and the spot arrangement of these laser beams is plural in a row in the main scanning direction and plural in a sub-scanning direction. This means that a two-dimensional plane array consisting of rows is used. By using a laser beam having a multi-beam two-dimensional array, the time required for laser recording can be reduced.

The laser beam to be used can be used without particular limitation as long as it is a multi-beam, and is a gas laser beam such as an argon ion laser beam, a helium neon laser beam, a helium cadmium laser beam, or a solid laser beam such as a YAG laser beam. Light, semiconductor laser light, dye laser light,
Direct laser light such as excimer 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 multicolor image forming method, it is preferable to use a semiconductor laser beam in consideration of output power, ease of modulation, and the like. In the multicolor image forming method, the laser beam has a beam diameter on the photothermal conversion layer of 5 to 50 μm (particularly 6 to 30 μm).
μm), and the scanning speed is 1 m / sec or more (especially 3 m / sec or more).
It is preferable that

In the multicolor image formation, the layer thickness of the image forming layer in the black thermal transfer sheet is larger than the layer thickness of the image forming layer in each of the yellow, magenta and cyan thermal transfer sheets, and 0.5 to 0.5. It is preferably 0.7 μm. By doing so, it is possible to suppress a decrease in density due to uneven transfer when the black thermal transfer sheet is irradiated with laser. When the thickness of the image forming layer in the black thermal transfer sheet is less than 0.5 μm, when recording with high energy, the image density is greatly reduced due to transfer unevenness, and the image density required as a proof of printing is achieved. It can be difficult. This tendency becomes more remarkable under high-humidity conditions, and the concentration change due to the environment may be large. On the other hand, if the layer thickness exceeds 0.7 μm, the transfer sensitivity may decrease during laser recording, and the attachment of small dots may worsen, or the thin line may become thin. This tendency is more pronounced under low humidity conditions. Further, the resolution may be deteriorated. The layer thickness of the image forming layer in the black thermal transfer sheet is more preferably 0.55 to 0.65 μm, and particularly preferably 0.60 μm.

Further, the thickness of the image forming layer in the black thermal transfer sheet is 0.5 to 0.7 μm, and the thickness of the image forming layer in each of the yellow, magenta and cyan thermal transfer sheets is 0 to 0.7 μm. .2μm or more and 0.5μm
It is preferably less than. The yellow, magenta,
When the layer thickness of the image forming layer in each of the thermal transfer sheets of cyan and cyan is less than 0.2 μm, the density may be reduced due to transfer unevenness during laser recording, while 0.5 μm
Above, the transfer sensitivity may decrease or the resolution may deteriorate. More preferably, it is 0.3 to 0.45 μm.

The image forming layer in the black thermal transfer sheet preferably contains carbon black, and the carbon black is composed of at least two types of carbon blacks having different coloring powers. This is preferable because the reflection density can be adjusted while keeping the ratio in a certain range. The coloring power of carbon black can be represented by various methods. For example, PVC black described in JP-A-10-140033 is used.
Blackness and the like. PVC blackness refers to the addition of carbon black to a PVC resin, dispersion and sheeting with two rolls, and carbon black “# 40” manufactured by Mitsubishi Chemical Corporation.
The blackness of “# 45” is set to 1 point and 10 points, respectively, and a reference value is determined.
The blackness of the sample was evaluated by visual sensation determination. PV
Two or more types of carbon blacks having different C blackness can be appropriately selected and used according to the purpose.

Hereinafter, a specific sample preparation method will be described. <Sample preparation method> Using a 250 cc Banbury mixer, 40% by mass of a sample carbon black is blended with LDPE (low density polyethylene) resin and kneaded at 115 ° C for 4 minutes. Compounding conditions LDPE resin 101.89 g Calcium stearate 1.39 g Irganox 1010 0.87 g Sample carbon black 69.43 g Next, the mixture is diluted with a two-roll mill at 120 ° C. so that the carbon black concentration becomes 1% by mass.

Diluting compound preparation conditions LDPE resin 58.3 g Calcium stearate 0.2 g Carbon black 40 mass% blended resin 1.5 g A sheet with slit width 0.3 mm, cut into chips and cut on a hot plate at 240 ° C. 65 ± 3μm
Into a film.

As a method of forming a multicolor image, as described above, the thermal transfer sheet is used to repeatedly form a large number of image layers (image forming layers on which images are formed) on the same image receiving sheet. A color image may be formed, or a multicolor image may be formed by forming an image once on the image receiving layers of a plurality of image receiving sheets and then retransferring the image to printing paper or the like.
For the latter, for example, a thermal transfer sheet having an image forming layer containing colorants having mutually different hues is prepared, and an image forming laminate obtained by combining this and an image receiving sheet is independently made of four types (four colors, Cyan, magenta, yellow and black). To each of the laminates, for example, through a color separation filter, irradiate a laser beam according to a digital signal based on the image, and subsequently peel off the thermal transfer sheet and the image receiving sheet, each color receiving image on each image receiving sheet Are formed independently. Next, each of the formed color separation images is
A multi-color image can be formed by sequentially laminating on an actual support such as a separately prepared printing paper or a similar support.

The thermal transfer recording using laser beam irradiation can convert an image forming layer containing a pigment to an image receiving sheet by converting a laser beam into heat and using the heat energy to form an image on the image receiving sheet. If present, pigment at the time of transfer,
The state change of the dye or the image forming layer is not particularly limited, and includes any of a solid state, a softened state, a liquid state, and a gaseous state, and is preferably a solid state or a softened state. Thermal transfer recording using laser light irradiation includes, for example, conventionally known melt-type transfer, ablation-based transfer, and sublimation-type transfer. Above all, the above-mentioned thin film transfer type,
The ablation type is preferable in that an image having a hue similar to printing is created.

In order to transfer the image receiving sheet on which the image has been printed by the recording apparatus to the printing paper (referred to as "paper"), a thermal laminator is usually used. When the image receiving sheet and the paper are overlapped and heat and pressure are applied, the two adhere to each other. Then, when the image receiving sheet is peeled off from the paper, only the image receiving layer containing the image remains on the paper. By connecting the above devices to the plate making system, a system that can exhibit the function as a color proof is constructed. As a system, it is necessary that a printed matter having an image quality as close as possible to a printed matter output from certain platemaking data be output from the recording device. Therefore, software for bringing colors and halftone dots closer to printed matter is required. Specific connection examples are described below. When proofing a printed material from a plate making system (for example, Celebra made by Fuji Photo Film Co., Ltd.), the system connection is as follows. Connect a CTP (Computer To Plate) system to the plate making system.
By applying the printing plate thus output to a printing machine, a final printed matter is obtained. The recording device is connected to the plate making system as a color proof, and a PD system (registered trademark) is connected as proof drive software for bringing colors and halftone dots closer to the printed matter. Contone (continuous tone) data converted to raster data by the plate making system is converted to binary data for halftone dots, output to the CTP system, and finally printed. On the other hand, the same contone data is also output to the PD system. The PD system converts the received data according to a four-dimensional (black, cyan, magenta, yellow) table so that the color matches the printed matter. Finally, the data is converted into binary data for a halftone dot so as to match the halftone dot of the printed matter, and output to a recording device. The four-dimensional table is created experimentally in advance and stored in the system. The experiment for making is as follows. An image in which important color data is printed via a CTP system and an image output from a recording device via a PD system are prepared, and their colorimetric values are compared to create a table so that the difference is minimized.

Hereinafter, the thermal transfer sheet and the image receiving sheet suitably used in the recording apparatus of the above system will be described. [Thermal Transfer Sheet] The thermal transfer sheet has at least a light-to-heat conversion layer and an image forming layer on a support, and further has other layers as necessary.

(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. The support preferably has rigidity, good dimensional stability, and withstands heat during image formation. Preferred examples of the support material include polyethylene terephthalate, polyethylene-2,6-naphthalate, polycarbonate, polymethyl methacrylate, polyethylene,
Polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, styrene-acrylonitrile copolymer, polyamide (aromatic or aliphatic), polyimide,
Synthetic resin materials such as polyamide imide and polysulfone can be mentioned. Among them, biaxially stretched polyethylene terephthalate is preferable in consideration of mechanical strength and dimensional stability against heat. When a color proof is produced using laser recording, the support of the thermal transfer sheet is preferably formed of a transparent synthetic resin material that transmits laser light. The thickness of the support is 25 to 130 μm
Is preferably, and particularly preferably 50 to 120 μm. The center line average surface roughness Ra (measured based on JIS B0601 using a surface roughness measuring device (Surfcom, manufactured by Tokyo Seiki Co., Ltd.)) of the support on the image forming layer side may be less than 0.1 μm. preferable. The Young's modulus of the support in the longitudinal direction is 200 to 1200 kg / mm.
² (≒ ^{2 to} 12 GPa) is preferable, and the Young's modulus in the width direction is 250 to 1600 kg / mm ² (≒ 2.5 to 16 GPa).
a) is preferred. F-5 in the longitudinal direction of the support
The value is preferably 5 to 50 kg / mm ² ($ 49 to 49
0 MPa), and the F-5 value in the support width direction is preferably 3
３０30 kg / mm ² (≒ 29.4 to 294 MPa), and the F-5 value in the support longitudinal direction is F-5 in the support width direction.
It is generally higher than the value, but this is not particularly necessary when it is necessary to increase the strength in the width direction. Further, the heat shrinkage at 100 ° C. for 30 minutes in the longitudinal direction and the width direction of the support is preferably 3% or less, more preferably 1.5% or less, and the heat shrinkage at 80 ° C. for 30 minutes is preferably 1%. Less than,
More preferably, it is 0.5% or less. The breaking strength is 5 to 100 kg / mm ² (≒ 49 to 980 MP in both directions).
a), the elastic modulus is 100 to 2000 kg / mm ² (≒ 0.
98 to 19.6 GPa).

The support of the thermal transfer sheet is subjected to a surface activation treatment and / or the provision of one or more undercoat layers in order to improve the adhesion to the light-to-heat conversion layer provided thereon. Is also good. 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 light-to-heat conversion layer, low thermal conductivity, and excellent 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. If necessary, various functional layers such as an antireflection layer and an antistatic layer, or a surface treatment can be applied to the surface of the thermal transfer sheet opposite to the side on which the photothermal conversion layer is provided.

(Back Layer) It is preferable to provide a back layer on the surface of the thermal transfer sheet of the present invention opposite to the side on which the light-to-heat conversion layer is provided. The back layer is preferably composed of two layers, a first back layer adjacent to the support and a second back layer provided on the side of the first back layer opposite to the support. In the present invention, the ratio B / A of the mass A of the antistatic agent contained in the first back layer to the mass B of the antistatic agent contained in the second back layer is preferably less than 0.3.
When B / A is 0.3 or more, slipperiness and powder dropping of the back layer tend to be deteriorated.

The thickness C of the first back layer is 0.01 to 1 μm.
m, more preferably 0.01 to 0.2 μm. In addition, the thickness D of the second back layer
Is preferably 0.01 to 1 μm, and 0.01 to 1 μm.
More preferably, it is 0.2 μm. The ratio C: D of the thickness of the first and second back layers is preferably 1: 2 to 5: 1.

Examples of the antistatic agent used in the first and second back layers include polyoxyethylene alkylamine,
Nonionic surfactants such as glycerin fatty acid esters,
Compounds such as cationic surfactants such as quaternary ammonium salts, anionic surfactants such as alkyl phosphate, amphoteric surfactants, and conductive resins can be used.

Further, conductive fine particles are used as an antistatic agent.
Can also be. As such conductive fine particles,
For example, ZnO, TiO_Two, SnO_Two, Al_TwoO_Three, In_Two
O_Three, MgO, BaO, CoO, CuO, Cu_TwoO, Ca
O, SrO, BaO_Two, PbO, PbO_Two, MnO_Three, M
oO_Three, SiO_Two, ZrO_Two, Ag_TwoO, Y_TwoO_Three, Bi
_TwoO_Three, Ti_TwoO_Three, Sb_TwoO_Three, Sb_TwoO_Five, K_TwoTi₆O₁₃,
NaCaP_TwoO₁₈, MgB_TwoO _FiveOxides such as CuS, Z
Sulfides such as nS; SiC, TiC, ZrC, VC, Nb
Carbides such as C, MoC and WC; Si_ThreeN_Four, TiN, Zr
N, VN, NbN, Cr_TwoNitride such as N; TiB_Two, Zr
B_Two, NbB_Two, TaB_Two, CrB, MoB, WB, La
B_FiveBorides such as TiSi_Two, ZrSi_Two, NbSi_Two, T
aSi_Two, CrSi_Two, MoSi_Two, WSi_TwoSilicides such as;
BaCO_Three, CaCO_Three, SrCO_Three, BaSO_Four, CaS
O_FourMetal salts such as SiN_Four-SiC, 9Al_TwoO_Three-2B_Two
O_ThreeAnd the like. One of these compounds may be used alone or in combination with two or more.
More than one species may be used in combination. Of these, SnO_Two, Z
nO, Al_TwoO_Three, TiO_Two, In_TwoO_Three, MgO, BaO
And MoO_ThreeAre preferred, and SnO_Two, ZnO, In_TwoO_ThreePassing
And TiO_TwoIs more preferable, and SnO_TwoIs particularly preferred.

When the thermal transfer sheet of the present invention is used in a laser thermal transfer recording system, the antistatic agent used in the back layer is preferably substantially transparent so that laser light can be transmitted.

When a conductive metal oxide is used as an antistatic agent, its particle size is preferably as small as possible to minimize light scattering, but the ratio of the refractive index of the particles to the binder is used as a parameter. It is to be determined and can be determined using Mie's theory. Generally, the average particle size is in the range of 0.001 to 0.5 μm, preferably in the range of 0.003 to 0.2 μm. Here, the average particle diameter is a value including not only the primary particle diameter of the conductive metal oxide but also the particle diameter of a higher-order structure.

The first and second back layers have a thickness of 400 to 9
Total light transmittance (I _O ) in the range of light wavelength of 00 nm
In addition to the above-described antistatic agent, various additives such as a surfactant, a slipping agent, a matting agent, and the like, to such an extent that the ratio (I / I _O ) of the non-diffusive transmittance (I) to the above does not deviate from the above range. A binder can be added. The amount of the antistatic agent contained in the first back layer is preferably from 10 to 1,000 parts by mass, and more preferably from 200 to 800 parts by mass based on 100 parts by mass of the binder.
Parts by mass are more preferred. The amount of the antistatic agent contained in the second back layer is preferably from 0 to 300 parts by mass, more preferably from 0 to 100 parts by mass, based on 100 parts by mass of the binder.

As the binder used for forming the first and second back layers, for example, homopolymers and copolymers of acrylic acid monomers such as acrylic acid, methacrylic acid, acrylates and methacrylates , Nitrocellulose, methylcellulose, ethylcellulose,
Cellulosic polymers such as cellulose acetate,
Polyethylene, polypropylene, polystyrene, vinyl chloride copolymer, vinyl chloride-vinyl acetate copolymer, polyvinylpyrrolidone, polyvinyl butyral, copolymer of vinyl polymer and vinyl compound such as polyvinyl alcohol, polyester, polyurethane, polyamide Such condensation polymers, rubber-based thermoplastic polymers such as butadiene-styrene copolymers, polymers obtained by polymerizing and crosslinking photopolymerizable or thermopolymerizable compounds such as epoxy compounds, melamine compounds, and the like. .

In the thermal transfer sheet of the present invention, the surface resistivity of the antistatic layer formed by the first back layer and the second back layer is preferably 1 × 10 ⁹ Ω / sq or less. When the surface resistivity on the antistatic layer side is within the above range, the condition of the surface resistivity on the image forming layer side described below is combined, and the integration of the thermal transfer sheet is improved.

(Light-to-heat conversion layer) The light-to-heat conversion layer contains a light-to-heat conversion substance, a binder, and if necessary, a matting agent.
Further, if necessary, other components are contained. The photothermal conversion substance is a substance having a function of converting irradiated light energy into heat energy. Generally, it is a dye capable of absorbing laser light (including a pigment; the same applies hereinafter). When performing image recording with an infrared laser, it is preferable to use an infrared absorbing dye as the photothermal conversion substance. Examples of the dye include black pigments such as carbon black, phthalocyanine, macrocyclic compounds having absorption in the visible to near-infrared region such as naphthalocyanine, and laser absorbers for high-density laser recording such as optical disks. Examples include organic dyes (cyanine dyes such as indolenine dyes, anthraquinone dyes, azulene dyes, and phthalocyanine dyes), and organic metal compound dyes such as dithiol nickel complexes. Above all, cyanine dyes have a high absorption coefficient for light in the infrared region, so when used as a light-to-heat conversion material, the light-to-heat conversion layer can be made thinner, and as a result, the recording sensitivity of the heat transfer sheet is reduced. It is preferable because it can be further improved. As the light-to-heat conversion material, an inorganic material such as a particulate metal material such as blackened silver can be used in addition to the pigment.

The binder contained in the light-to-heat conversion layer has at least a strength capable of forming a layer on a support,
Resins having high thermal conductivity are preferred. Furthermore, in the case of image recording, if the resin is heat resistant and does not decompose even by the heat generated from the light-to-heat conversion material, the surface of the light-to-heat conversion layer after light irradiation can be smoothed even if high-energy light irradiation is performed. It is preferable because it can be maintained. Specifically, the thermal decomposition temperature (T
A resin having a temperature of 10 ° C./min in a GA method (temperature at which the mass is reduced by 5% in an air stream at a heating rate of 10 ° C./min.) Is preferably 400 ° C. or more, and the resin having a thermal decomposition temperature of 500 ° C. or more is preferred. More preferred. Also, the binder is 200 to 400 ° C.
It preferably has a glass transition temperature of 250 to 35.
More preferably, it has a glass transition temperature of 0 ° C. When the glass transition temperature is lower than 200 ° C., fogging may occur in an image to be formed, and when the glass transition temperature is higher than 400 ° C., the solubility of the resin may be reduced and the production efficiency may be reduced.
In addition, it is preferable that the heat resistance (for example, thermal deformation temperature and thermal decomposition temperature) of the binder of the light-to-heat conversion layer is higher than the material used for the other layers provided on the light-to-heat conversion layer.

Specifically, acrylic resins such as polymethyl methacrylate, polycarbonate, polystyrene,
Vinyl chloride / vinyl acetate copolymer, vinyl resin such as polyvinyl alcohol, polyvinyl butyral, polyester, polyvinyl chloride, polyamide, polyimide, polyetherimide, polysulfone, polyethersulfone, aramid, polyurethane, epoxy resin, urea / melamine Resins. Among these, a polyimide resin is preferable.

In particular, the polyimide resins represented by the following general formulas (I) to (VII) are soluble in an organic solvent, and the use of these polyimide resins is preferable because the productivity of the thermal transfer sheet is improved. It is also preferable in that the viscosity stability, long-term storage property, and moisture resistance of the light-to-heat conversion layer coating solution are improved.

[0063]

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In the general formulas (I) and (II), Ar
¹ represents an aromatic group represented by the following structural formulas (1) to (3), and n represents an integer of 10 to 100.

[0065]

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[0066]

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In the above general formulas (III) and (IV), Ar
² represents an aromatic group represented by the following structural formulas (4) to (7), and n represents an integer of 10 to 100.

[0068]

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[0069]

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In the above general formulas (V) to (VII), n and m
Represents an integer of 10 to 100. In the formula (VI), n:
The ratio of m is from 6: 4 to 9: 1.

As a criterion for judging whether or not the resin is soluble in an organic solvent, it is based on the fact that at 25 ° C., at least 10 parts by mass of the resin is dissolved with respect to 100 parts by mass of N-methylpyrrolidone. When it is dissolved in 10 parts by mass or more, it is preferably used as a resin for the light-to-heat conversion layer. More preferably, the resin dissolves in 100 parts by mass or more with respect to 100 parts by mass of N-methylpyrrolidone.

The matting agent contained in the light-to-heat conversion layer includes inorganic fine particles and organic fine particles. Examples of the inorganic fine particles include 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 oxide, and the like. Examples include lead white, zeeklite, quartz, diatomaceous earth, barlite, bentonite, mica, and synthetic mica. As organic fine particles, fluororesin particles,
Resin particles such as guanamine resin particles, acrylic resin particles, styrene-acryl copolymer resin particles, silicone resin particles, melamine resin particles, and epoxy resin particles can be exemplified.

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

A surfactant, a thickener, an antistatic agent and the like may be further added to the light-to-heat conversion layer, if necessary.

The light-to-heat conversion layer is prepared by dissolving a light-to-heat conversion substance and a binder, preparing a coating solution containing a matting agent and other components as necessary, coating the solution on a support, and drying. Can be provided. Examples of the organic solvent for dissolving the polyimide resin include, for example, n
-Hexane, cyclohexane, diglyme, xylene,
Toluene, ethyl acetate, tetrahydrofuran, methyl ethyl ketone, acetone, cyclohexanone, 1,4-dioxane, 1,3-dioxane, dimethyl acetate,
N-methyl-2-pyrrolidone, dimethylsulfoxide, dimethylformamide, dimethylacetamide, γ
-Butyrolactone, ethanol, methanol 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 lower, preferably at a temperature of 200 ° C. or lower. When polyethylene terephthalate is used as the support, drying is preferably performed at a temperature of 80 to 150 ° C.

If the amount of the binder in the light-to-heat conversion layer 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. It causes color mixing. On the other hand, if the amount of the polyimide resin is too large, the layer thickness of the light-to-heat conversion layer becomes large in order to achieve a certain light absorption rate, and the sensitivity tends to decrease. The mass ratio of the solid content of the light-to-heat conversion material to the binder in the light-to-heat conversion layer is preferably from 1:20 to 2: 1, and more preferably from 1:10 to 2: 1.

Further, it is preferable to make the light-to-heat conversion layer thin, as described above, because the sensitivity of the heat transfer sheet can be increased.
The light-to-heat conversion layer preferably has a thickness of 0.03 to 1.0 μm, more preferably 0.05 to 0.5 μm. Further, the light-to-heat conversion layer has a wavelength of 808 nm, which is 0.1 mm.
It is preferable to have an optical density of 80 to 1.26 because the transfer sensitivity of the image forming layer is improved, and to have an optical density of 0.92 to 1.15 for light having the above-mentioned wavelength. More preferred. The optical density at the laser peak wavelength is 0.
If it is less than 80, it becomes insufficient to convert the irradiated light into heat, and the transfer sensitivity may decrease. on the other hand,
When the ratio exceeds 1.26, the function of the light-to-heat conversion layer is affected during recording, and fog may occur.

In the present invention, the optical density of the light-to-heat conversion layer of the thermal transfer sheet refers to the absorbance of the light-to-heat conversion layer at the peak wavelength of the laser beam used when recording the image forming material of the present invention. Can be used to perform the measurement. In the present invention, a UV-spectrophotometer UV-240 manufactured by Shimadzu Corporation was used. The optical density is a value obtained by subtracting the value of the support alone from the value including the support.

(Image Forming Layer) The image forming layer contains at least a pigment which is transferred to an image receiving sheet to form an image, and further contains a binder for forming a layer and, if desired, other components. I do. Pigments are generally classified into organic pigments and inorganic pigments.The former has properties such as excellent transparency of the coating film, and the latter generally has properties such as excellent concealing properties, and can be appropriately selected according to the application. I just need. When the thermal transfer sheet is used for printing color proofing, organic pigments that match or have a similar color tone to yellow, magenta, cyan, and black generally used for printing inks are 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 pigments used in the image forming layer are listed below for each hue, but are not limited thereto.

1) Yellow Pigment Pigment Yellow
12 (CI No. 21090) Example) Permanent Yellow (Permanent Yellow) DHG (Clariant Japan K.K.)
Lionol Yellow 1212B (manufactured by Toyo Ink Mfg. Co., Ltd.), Irg
alite Yellow (Ilgarite Yellow)
LCT (Ciba Specialty Chemicals Co., Ltd.)
Pigment Yellow (manufactured by Dainippon Ink & Chemicals, Inc.) GTF 219 (manufactured by Dainippon Ink and Chemicals, Inc.)
13 (CI No. 21100) Example: Permanent Yellow (Permanent Yellow) GR (manufactured by Clariant Japan K.K.),
Lionol Yellow
1313 (manufactured by Toyo Ink Mfg. Co., Ltd.) Pigment Yellow
14 (CI No. 21095) Example) Permanent Yellow (Permanent Yellow) G (manufactured by Clariant Japan KK), L
ionol Yellow 1
401-G (manufactured by Toyo Ink Mfg. Co., Ltd.), Seika
Fast Yellow (Seika First Yellow)
2270 (manufactured by Dainichi Seika Kogyo Co., Ltd.), Symuler
Fast Yellow 4400 (manufactured by Dainippon Ink and Chemicals, Inc.) Pigment Yellow (Pigment Yellow)
17 (CI No. 21105) Example) Permanent Yellow (Permanent Yellow) GG02 (Clariant Japan K.K.)
Pigment Yellow (manufactured by Dainippon Ink and Chemicals, Inc.) 8GF (manufactured by Dainippon Ink and Chemicals, Inc.)
155 Example) Graphtol Yellow (Graftor Yellow) 3GP (manufactured by Clariant Japan KK) Pigment Yellow (Pigment Yellow)
180 (CI No. 21290) Example) Novoperm Yellow (Novo Palm Yellow) P-HG (manufactured by Clariant Japan K.K.),
PV Fast Yellow
HG (manufactured by Clariant Japan KK) Pigment Yellow (Pigment Yellow)
139 (CI No. 56298) Example) Novoperm Yellow (Novo Palm Yellow) M2R 70 (Clariant Japan K.K.)
Made)

2) Magenta Pigment Red (Pigment Red) 57:
1 (CI No. 15850: 1) Example) Graphtol Rubine L6B (manufactured by Clariant Japan KK), L
ionol Red (Rionol Red) 6B-42
90G (manufactured by Toyo Ink Mfg. Co., Ltd.), Irgalite
Rubine (Ilgarite Rubin) 4BL (Ciba Specialty Chemicals Co., Ltd.), Symu
ler Brilliant Carmine 6B-229 (manufactured by Dainippon Ink and Chemicals, Inc.) Pigment Red (Pigment Red) 122
(C.I. No. 73915) Example) Hosterperm Pink (Hoster Palm Pink) E (manufactured by Clariant Japan K.K.), Li
onogen Magenta
5790 (manufactured by Toyo Ink Manufacturing Co., Ltd.), Fastog
en Super Magenta RH (Dainippon Ink & Chemicals, Inc.)
Pigment Red 53:
1 (CI No. 15585: 1) Example) Permanent Lake Red (Permanent Lake Red) LCY (manufactured by Clariant Japan KK), Symler Lake Red (Shimla Lake Red) C conc (Dainippon Ink & Chemicals, Inc.) )) Pigment Red (Pigment Red) 48:
1 (CI No. 15865: 1) Example) Lionol Red 2B
3300 (manufactured by Toyo Ink Manufacturing Co., Ltd.), Symule
r Red (Shimler Red) NRY (manufactured by Dainippon Ink and Chemicals, Inc.) Pigment Red (Pigment Red) 48:
2 (CI No. 15865: 2) Example) Permanent Red (Permanent Red) W2T (manufactured by Clariant Japan KK), Li
onol Red (Lionol Red) LX235
(Manufactured by Toyo Ink Manufacturing Co., Ltd.), Symler Red
(Shimler Red) 3012 (manufactured by Dainippon Ink and Chemicals, Inc.) Pigment Red 48:
3 (CI No. 15865: 3) Example) Permanent Red (Permanent Red) 3RL (manufactured by Clariant Japan KK), Sy
muller Red (Shimler Red) 2BS (manufactured by Dainippon Ink and Chemicals, Inc.) Pigment Red (Pigment Red) 177
(CI. No. 65300) Example) Cromophthal Red (Chromophthal Red) A2B (manufactured by Ciba Specialty Chemicals Co., Ltd.)

3) Cyan pigment Pigment Blue (Pigment Blue) 15
(C.I. No. 74160) Example) Lionol Blue 7
027 (manufactured by Toyo Ink Manufacturing Co., Ltd.), Fastogen
Blue (fastogen blue) BB (manufactured by Dainippon Ink and Chemicals, Inc.) Pigment Blue (pigment blue) 1
5: 1 (CI No. 74160) Example) Hosterperm Blue (Hoster Palm Blue) A2R (manufactured by Clariant Japan KK),
Fastogen Blue (fastogen blue)
5050 (manufactured by Dainippon Ink and Chemicals, Inc.) Pigment Blue 1
5: 2 (CI No. 74160) Example) Hosterperm Blue (Hoster Palm Blue) AFL (manufactured by Clariant Japan KK),
Irgalite Blue (Irgalite Blue)
BSP (Ciba Specialty Chemicals Co., Ltd.)
Pigment Blue (Pigment Blue) 1 Fastogen Blue (Fastgen Blue) GP (Dai Nippon Ink Chemical Industry Co., Ltd.)
5: 3 (CI No. 74160) Example) Hosterperm Blue (Hoster Palm Blue) B2G (manufactured by Clariant Japan K.K.),
Lionol Blue FG73
30 (manufactured by Toyo Ink Manufacturing Co., Ltd.), Cromophta
l Blue (Chromophthal Blue) 4GNP (Ciba Specialty Chemicals Co., Ltd.), Fast
oogen Blue FGF
(Manufactured by Dainippon Ink and Chemicals, Inc.) Pigment Blue 1
5: 4 (CI No. 74160) Example) Hosterperm Blue (Hoster Palm Blue) BFL (manufactured by Clariant Japan KK),
Cyanine Blue (Cyanine Blue) 700-
10FG (manufactured by Toyo Ink Mfg. Co., Ltd.), Irgalit
e Blue (Irgarite Blue) GLNF (manufactured by Ciba Specialty Chemicals Co., Ltd.), Fast
oogen Blue FGS
(Manufactured by Dainippon Ink and Chemicals, Inc.) Pigment Blue 1
5: 6 (CI No. 74160) Example) Lionol Blue E
S (manufactured by Toyo Ink Mfg. Co., Ltd.) Pigment Blue 60
(C.I. No. 69800) Example) Hosterperm Blue (Hoster Palm Blue) RL01 (Clariant Japan K.K.)
Manufactured by Toyo Ink Mfg. Co., Ltd.), Lionogen Blue (Rionogen Blue) 6501 (manufactured by Toyo Ink Mfg. Co., Ltd.)

4) Black Pigment Pigment Black
7 (carbon black CI No. 77266) Example) Mitsubishi carbon black MA100 (manufactured by Mitsubishi Chemical Corporation), Mitsubishi carbon black # 5 (manufactured by Mitsubishi Chemical Corporation), Black Pearls (Black Pearls) 430 (Cabot) Co. (Cabot Corporation)
Pigments that can be used in the present invention include “Pigment Handbook, edited by Japan Pigment Technical Association, Seibundo Shinkosha, 198
9 "," COLOUR INDEX, THE SOCIETY OF
DYES & COLOURIST, THIRD EDITION, 1987 "
The product can be selected as appropriate by referring to the table.

The pigment has an average particle size of from 0.03 to
1 μm is preferable, and 0.05 to 0.5 μm is more preferable. When the particle size is less than 0.03 μm, the dispersion cost may increase, or the dispersion may cause gelation,
On the other hand, if it exceeds 1 μm, coarse particles in the pigment may hinder the adhesion between the image forming layer and the image receiving layer,
This may hinder the transparency of the image forming layer.

The binder for the image forming layer is preferably an amorphous organic high molecular polymer having a softening point of 40 to 150 ° C. As the amorphous organic high-molecular polymer, for example, butyral resin, polyamide resin, polyethyleneimine resin, sulfonamide resin, polyester polyol resin, petroleum resin, styrene, vinyltoluene, α-methylstyrene, 2-methylstyrene, Styrene and its derivatives such as chlorostyrene, vinylbenzoic acid, sodium vinylbenzenesulfonate and aminostyrene, and homo- and copolymers of substituted methacrylates such as methyl methacrylate, ethyl methacrylate, butyl methacrylate and hydroxyethyl methacrylate And acrylates such as methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate and α-ethylhexyl acrylate; and dienes such as acrylic acid, butadiene and isoprene; Use of vinyl monomers such as rilonitrile, vinyl ethers, maleic acid and maleic esters, maleic anhydride, cinnamic acid, vinyl chloride, vinyl acetate, or copolymers with other monomers Can be. These resins can be used as a mixture of two or more kinds.

The image forming layer preferably contains a pigment and an amorphous organic high molecular polymer in a mass ratio of 30/70 to 70/30 (pigment / polymer).
More preferably, it is contained at a mass ratio of 50. Further, the image forming layer preferably contains 70 to 30% by mass of resin, more preferably 70 to 40% by mass.

The image forming layer can contain the following components as the above-mentioned other components. Waxes Examples of the waxes include mineral waxes, natural waxes, and synthetic waxes. Examples of the mineral wax include petroleum wax such as paraffin wax, microcrystalline wax, ester wax, and oxidized wax, montan wax, ozokerite, and ceresin. Above all, paraffin wax is preferred. The paraffin wax is separated from petroleum, and various types are commercially available depending on the melting point. Examples of the natural waxes include vegetable waxes such as carnauba wax, wood wax, ouriculi wax, and spal wax, and animal waxes such as beeswax, insect wax, shellac wax, and whale wax.

The synthetic wax is generally used as a lubricant, and usually comprises a higher fatty acid compound. Examples of such synthetic waxes include the following. 1) Fatty acid-based wax Linear saturated fatty acid represented by the following general formula: CH ₃ (CH ₂ ) nCOOH In the above formula, n represents an integer of 6 to 28. Specific examples include stearic acid, behenic acid, palmitic acid, 12-hydroxystearic acid, azelaic acid and the like.
In addition, metal salts such as the above fatty acids (for example, K, Ca, Z
n, Mg, etc.). 2) Fatty acid ester-based wax Specific examples of the fatty acid ester include ethyl stearate, lauryl stearate, ethyl behenate, hexyl behenate, and behenyl myristate. 3) Fatty acid amide-based wax Specific examples of the amide of the fatty acid include stearic acid amide and lauric acid amide. 4) Aliphatic alcohol wax A linear saturated aliphatic alcohol represented by the following general formula: CH ₃ (CH ₂ ) nOH In the above formula, n represents an integer of 6 to 28. Specific examples include stearyl alcohol and the like.

Among the synthetic waxes 1) to 4), higher fatty acid amides such as stearic acid amide and lauric acid amide are particularly preferable. In addition, the said wax-type compound can be used individually or in suitable combination as needed.

Plasticizer The plasticizer is preferably an ester compound. Dibutyl phthalate, di-n-octyl phthalate, di (2-ethylhexyl) phthalate, dinonyl phthalate, dilauryl phthalate, butyllauryl phthalate, Phthalates such as butylbenzyl phthalate and di (2-diphenyl adipate)
Aliphatic dibasic acid esters such as ethylhexyl) and di (2-ethylhexyl) sebacate; phosphoric acid triesters such as tricresyl phosphate and tri (2-ethylhexyl) phosphate; polyol polyesters such as polyethylene glycol ester; epoxy Known plasticizers such as an epoxy compound such as a fatty acid ester can be used. Of these, esters of vinyl monomers, particularly esters of acrylic acid or methacrylic acid, are preferred because they have a large effect of improving transfer sensitivity, improving transfer unevenness, and controlling elongation at break by addition.

Examples of the ester compound of acrylic acid or methacrylic acid include polyethylene glycol dimethacrylate, 1,2,4-butanetriol trimethacrylate, trimethylolethane triacrylate, pentaerythritol acrylate, pentaerythritol tetraacrylate, and dipentaerythritol. Polyacrylate and the like.

The plasticizer may be a polymer. Among them, polyester is preferable because of its large addition effect and difficulty in diffusing under storage conditions. Examples of the polyester include sebacic acid-based polyester and adipic acid-based polyester. The additives to be contained in the image forming layer are not limited to these. The plasticizer may be used alone or in combination of two or more.

If the content of the additive in the image forming layer is too large, the resolution of the transferred image is reduced, the film strength of the image forming layer itself is reduced, and the adhesion between the photothermal conversion layer and the image forming layer is reduced. In some cases, transfer of the unexposed portion to the image receiving sheet occurs due to a decrease in the force. From the above viewpoint, the content of the wax is preferably from 0.1 to 30% by mass, more preferably from 1 to 20% by mass of the total solids in the image forming layer. The content of the plasticizer is preferably from 0.1 to 20% by mass, more preferably from 0.1 to 10% by mass of the total solids in the image forming layer.

Others The image forming layer further comprises a surfactant,
It may contain inorganic or organic fine particles (metal powder, silica gel, etc.), oils (linseed oil, mineral oil, etc.), thickeners, antistatic agents and the like. 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 that absorbs the wavelength of the light source may be any of a pigment and a dye. It is preferable in terms of color reproduction to use a dye having a large absorption at the wavelength of the light source. Examples of near infrared dyes include:
The compounds described in JP-A-3-103476 can be exemplified.

For the image forming layer, a coating solution prepared by dissolving or dispersing the pigment and the binder and the like is prepared, and the solution is coated on the light-to-heat conversion layer (if the heat-sensitive release layer described below is provided on the light-to-heat conversion layer, On the layer) and dried. As the solvent used for preparing the coating solution,
Examples include n-propyl alcohol, methyl ethyl ketone, propylene glycol monomethyl ether (MFG), methanol, water and the like. Coating and drying are normal coating,
It can be performed using a drying method.

On the light-to-heat conversion layer of the thermal transfer sheet,
Providing a heat-sensitive release layer containing a heat-sensitive material that generates gas by the action of heat generated in the light-to-heat conversion layer or releases attached water and the like, thereby weakening the bonding strength between the light-to-heat conversion layer and the image forming layer. Can be. Examples of such heat-sensitive materials include compounds (polymers or 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 water (polymer). Or low molecular weight compounds). These may be used in combination.

Examples of the polymer which decomposes or degrades by heat to generate a gas include self-oxidizing polymers such as nitrocellulose, chlorinated polyolefin, chlorinated rubber, polyvinyl chloride, polyvinyl chloride, and polyvinylidene chloride. Such halogen-containing polymers, acrylic compounds such as polyisobutyl methacrylate in which volatile compounds such as water are adsorbed, cellulose esters such as ethyl cellulose in 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 azide compound. In addition, the decomposition or deterioration of the heat-sensitive material due to heat as described above preferably occurs at 280 ° C. or less, particularly preferably at 230 ° C. or less.

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, a polymer which itself decomposes or degrades by heat to generate a gas can be used, but a normal binder having no such properties can also be used. When a heat-sensitive low-molecular compound and a binder are used in combination, the mass ratio of the former to the latter is preferably 0.02: 1 to 3: 1,
More preferably, the ratio is 0.05: 1 to 2: 1. The heat-sensitive release layer desirably covers the light-to-heat conversion layer over substantially the entire surface thereof.
1 μm, and preferably in the range of 0.05 to 0.5 μm.

On a support, a light-to-heat conversion layer, a heat-sensitive release layer,
In the case of a thermal transfer sheet having a configuration in which the image forming layers are laminated in this order, the heat-sensitive release layer decomposes and degrades by the heat transmitted from the light-to-heat conversion layer to generate gas. Then, due to the decomposition or the 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 no visual color mixture appears in the formed image. It is desirable to show permeability. Specifically, the light-absorbing rate of the heat-sensitive release layer is 50% or less, preferably 1 to visible light.
0% or less. In addition, instead of providing an independent heat-sensitive release layer on the thermal transfer sheet, the heat-sensitive material is added to a light-to-heat conversion layer coating solution to form a light-to-heat conversion layer. It can also be set as a structure.

It is preferable that the coefficient of static friction of the outermost layer on the side where the image forming layer of the thermal transfer sheet is coated is 0.35 or less, preferably 0.20 or less. By setting the coefficient of static friction of the outermost layer to 0.35 or less, it is possible to eliminate roll contamination when the thermal transfer sheet is conveyed, and to improve the quality of the formed image. The method for measuring the coefficient of static friction is described in Japanese Patent Application No. 2000-85759.
According to paragraph (0011). The smoother value of the surface of the image forming layer is 0.5 to 5 at 23 ° C. and 55% RH.
0 mmHg (≒ 0.0665 to 6.65 kPa) is preferable, and Ra is preferably 0.05 to 0.4 μm. Micro gaps can be reduced, which is preferable in terms of transfer and further image quality. The Ra value can be measured based on JIS B0601 using a surface roughness measuring device (Surfcom, manufactured by Tokyo Seiki Co., Ltd.) or the like. The surface hardness of the image forming layer is preferably 10 g or more with a sapphire needle. US Federal Exam Standard 4046
After charging the thermal transfer sheet by the method described above, the charge potential of the image forming layer 1 second after the thermal transfer sheet is grounded is -100 to 100.
V is preferred. The surface specific resistance of the thermal transfer sheet of the present invention on the image forming layer side is 23 ° C. and 50% RH.
(Relative humidity) is 1 × 10
It is preferably at most ¹⁵ Ω / sq, more preferably at most 1 × 10 ¹⁵ Ω / sq.

(Heat Insulation Layer) In the second embodiment of the thermal transfer sheet of the present invention, a heat insulation layer is provided between the support and the light-to-heat conversion layer. Providing the heat insulating layer is effective in improving the transfer sensitivity because the thermal energy applied during the thermal transfer is efficiently held. There are various methods for forming the heat insulating layer, a method of using a resin having a small thermal conductivity as a binder which is a main component of the heat insulating layer, a method of containing hollow particles having air in the heat insulating layer, There is a method of forming fine holes and the like. As a binder in the method of using a resin having a small thermal conductivity as a binder serving as a main component of the heat insulating layer, for example, polyisobutylene, polytetrafluoroethylene, polychlorotrifluoroethylene, polyparachlorostyrene, polyvinylidene fluoride, Polyvinyl chloride, polystyrene, polyisobutene-co-isoprene and the like can be mentioned. In the method including the hollow particles having air in the heat insulating layer, the hollow particles to be used can be composed of a synthetic resin. As the synthetic resin, various resins can be used, and from the viewpoint of heat resistance and acquisition cost, a vinylidene chloride-based resin, a vinylidene chloride-based copolymer, and the like can be given. The binder for dispersing and holding the hollow particles is not particularly limited, but styrene-butadiene rubber, styrene-methacrylate-butadiene rubber, acrylic resin, acryl-styrene resin, acryl-maleic acid resin, acryl-vinyl acetate resin And emulsion-type synthetic resins such as ethylene-vinyl acetate resin, water-soluble polymers such as polyvinyl alcohol, starch and casein, carboxymethylcellulose, and polyethylene oxide. As a method of forming fine pores in the heat insulating layer, for example, it can be produced by a method of including inorganic particles in a resin such as polypropylene and forming fine pores by stretching. Regarding the above, JP-A-5-309959 and JP-A-7-15656
No. 1, JP-A-11-11032, JP-A-11-277
917, etc. In the present invention, polyvinyl acetate (PVA), gelatin and the like are preferably used.

Next, an image receiving sheet which can be used in combination with the thermal transfer sheet will be described. [Image-Receiving Sheet] (Layer Structure) The image-receiving sheet is usually composed of a support,
One or more image receiving layers are provided, and if desired, one or more of a cushion layer, a release layer, and an intermediate layer are provided between the support and the image receiving layer. It is preferable to have a back layer on the surface of the support opposite to the image receiving layer from the viewpoint of transportability.

(Support) As a support, a plastic sheet, a metal sheet, a glass sheet, a resin-coated paper,
Examples include ordinary sheet-like substrates such as paper and various composites. Examples of the plastic sheet include a polyethylene terephthalate sheet, a polycarbonate sheet, a polyethylene sheet, a polyvinyl chloride sheet, a polyvinylidene chloride sheet, a polystyrene sheet, a styrene-acrylonitrile sheet, and a polyester sheet. As the paper, printing paper, coated paper, or the like can be used.

It is preferable that the support has minute voids (voids) because the image quality can be improved. Such a support is, for example, a thermoplastic resin, a mixed melt obtained by mixing an inorganic pigment or a filler made of an incompatible polymer or the like with the thermoplastic resin, a single layer or a multilayer by a melt extruder. It can be produced by forming a film and further stretching it uniaxially or biaxially. In this case, the porosity is determined by the selection of the resin and the filler, the mixing ratio, the stretching conditions, and the like.

As the thermoplastic resin, a polyolefin resin such as polypropylene and a polyethylene terephthalate resin are preferable because of good crystallinity, good stretchability, and easy formation of voids. It is preferable to use the above-mentioned polyolefin resin or polyethylene terephthalate resin as a main component, and appropriately use a small amount of another thermoplastic resin in combination. As the inorganic pigment used as the filler, those having an average particle size of 1 to 20 μm are preferable, and calcium carbonate, clay, diatomaceous earth, titanium oxide, aluminum hydroxide, silica and the like can be used. When polypropylene is used as the thermoplastic resin as the incompatible resin used as the filler, it is preferable to combine polyethylene terephthalate as the filler. Details of the support having minute voids (voids) are described in Japanese Patent Application No. 11-290570. The content of the filler such as an inorganic pigment in the support is 2 to 30 by volume.
% Is common.

The thickness of the support of the image receiving sheet is usually from 10 to
It is 400 μm, preferably 25 to 200 μm. Further, the surface of the support is subjected to a surface treatment such as a corona discharge treatment or a glow discharge treatment in order to enhance the adhesion with the image receiving layer (or the cushion layer) or the adhesion with the image forming layer of the thermal transfer sheet. It may be.

(Image-Receiving Layer) In order to transfer the image-forming layer to the surface of the image-receiving sheet and fix it, it is preferable to provide one or more image-receiving layers on the support. The image receiving layer is preferably a layer formed mainly of an organic polymer binder. The binder is preferably a thermoplastic resin, for example, acrylic acid, methacrylic acid,
Acrylic esters, homopolymers and copolymers of acrylic monomers such as methacrylic esters, methylcellulose, ethylcellulose, cellulosic polymers such as cellulose acetate, polystyrene, polyvinylpyrrolidone, polyvinylbutyral, polyvinyl alcohol, polyvinyl chloride, Homopolymers of vinyl monomers such as styrene / maleic acid copolymer half-esterified products, styrene / fumaric acid copolymer half-esterified products, styrene / acrylic acid copolymer esterified products, and copolymers thereof , Polyester, polyamide and the like, and rubber-based polymers such as butadiene-styrene copolymer. Above all, at least one selected from a half-esterified product of polyvinyl butyral or a styrene / maleic acid copolymer, a half-esterified product of a styrene / fumaric acid copolymer, and an esterified product of a styrene / acrylic acid copolymer is used as a polymer binder. It is preferable to use as. The binder polymer described above may be used in combination of two or more kinds, but a half-esterified product of polyvinyl butyral or a styrene / maleic acid copolymer, a half-esterified product of a styrene / fumaric acid copolymer, and a styrene / acrylic acid copolymer The content is preferably 10% by mass or more and 40% by mass or less of the binder polymer in which at least one selected from the unified esterified product is used.

The binder of the image receiving layer is used in order to obtain a proper adhesive strength between the image receiving layer and the image forming layer.
Is preferably a polymer having a temperature lower than 90 ° C. For this purpose, it is also possible to add a plasticizer to the image receiving layer.
Further, the binder polymer 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, a polymer which is the same as or similar to the binder polymer of the image forming layer may be used in terms of improving adhesion with the image forming layer during laser recording and improving sensitivity and image strength. Particularly preferred.

The smoother value of the surface of the image receiving layer is 23 ° C., 5
0.5 to 50 mmHg at 5% RH ($ 0.0665 to
6.65 kPa) and Ra is 0.05 to
Preferably, the thickness is 0.4 μm, whereby a large number of microscopic voids where the image receiving layer and the image forming layer cannot contact each other at the contact surface can be reduced, which is preferable in terms of transfer and further image quality. The Ra value is measured by a surface roughness measuring device (Surfcom,
It can be measured based on JIS B0601 using, for example, Tokyo Seiki Co., Ltd.). US Federal Exam Standard 40
After the image receiving sheet is charged by 46, the charging potential of the image receiving layer 1 second after the image receiving sheet is grounded is preferably -100 to 100 V. The surface resistance of the image receiving layer is 23 ° C., 55
% RH is preferably 10 ⁹ Ω or less. The coefficient of static friction on the surface of the image receiving layer is preferably 0.8 or less.
The surface energy of the surface of the image receiving layer is preferably 23 to 35 mg / m ² .

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 above polyfunctional vinyl monomer,
Unsaturated esters of polyols, especially esters of acrylic acid or methacrylic acid (eg, ethylene glycol diacrylate, pentaerythritol tetraacrylate) are used.

Examples of the organic polymer include the 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 mass in the layer.

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

(Other Layers) Between the support and the image receiving layer,
It is preferable to provide a cushion layer. By providing a cushion layer, the adhesion between the image forming layer and the image receiving layer can be improved during laser thermal transfer, and the image quality can be improved. 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 image forming layer is reduced due to the deformation action of the cushion layer, and as a result, the size of image defects such as white spots is reduced. You can also. Further, when an image is transferred and formed and then transferred to a separately prepared printing paper or the like, the image receiving surface is deformed according to the uneven surface of the paper, so that the transferability of the image receiving layer can be improved, and By reducing the gloss of the object, the similarity with the printed matter can be improved.

The cushion layer is easily deformed when a stress is applied to the image receiving layer. To achieve the above effect, a material having a low elastic modulus, a material having rubber elasticity, or a material which is easily softened by heating. It is preferred to be made of a thermoplastic resin. The elastic modulus of the cushion layer at room temperature is preferably 0.5 MPa to 1.0 GPa, particularly preferably 1 MPa to 0.5 GPa, and more preferably 10 to 100 GPa.
MPa. In addition, in order to allow foreign matter such as dust to be sunk, the penetration (25
(C, 100 g, 5 seconds) is preferably 10 or more. Further, the glass transition temperature of the cushion layer is 80 ° C. or less, preferably 25 ° C. or less, and the softening point is preferably 50 to 200 ° C. It is also possible to suitably add a plasticizer to the 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.
Preferably it is 10 to 52 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. If the layer thickness is too large, the performance of the cushion layer becomes difficult to appear, so it is necessary to adjust the thickness depending on the type of the release layer. Specific examples of the binder for the release layer include polyolefin, polyester, polyvinyl acetal, polyvinyl formal, polyparabanic acid, polymethyl methacrylate, polycarbonate, ethyl cellulose, nitrocellulose, methylcellulose, carboxymethylcellulose, hydroxypropylcellulose, polyvinyl alcohol, and polyvinyl chloride. , Urethane resin,
Tg of fluorine-based resin, styrenes such as polystyrene, acrylonitrile styrene and the like, and those obtained by cross-linking these resins, polyamide, polyimide, polyetherimide, polysulfone, polyethersulfone, and aramid have a Tg of 65 ° C.
The above-mentioned thermosetting resins and cured products of these resins are included. As the curing agent, a general curing agent such as isocyanate and melamine can be used.

When a binder for the release layer is selected in accordance with the above physical properties, polycarbonate, acetal, and ethyl cellulose are preferred in terms of preservability. Further, when an acrylic resin is used for the image receiving layer, the resin is peeled off when the image after laser thermal transfer is retransferred. This is particularly preferable because the properties are good. Separately, a layer having extremely low adhesiveness to the image receiving layer upon cooling can be used as the release layer. Specifically, a layer mainly composed of a heat-fusible compound such as a wax or a binder or a thermoplastic resin can be used. Examples of the heat-fusible compound include substances described in JP-A-63-193886. In particular, microcrystalline wax, paraffin wax, carnauba wax and the like are preferably used. As the thermoplastic resin, an ethylene copolymer such as an ethylene-vinyl acetate resin, a cellulose resin, or the like is preferably used.

As needed, higher fatty acids, higher alcohols, higher fatty acid esters, amides, higher amines and the like can be added to such a release layer.
Another configuration of the release layer is a layer having a releasability by melting or softening upon heating to cause cohesive failure itself. Preferably, such a release layer contains a supercooled substance. Examples of the supercooled substance include poly-ε-caprolactone, polyoxyethylene, benzotriazole, tribenzylamine, and vanillin. Further, the peelable layer having another structure contains a compound that reduces the adhesiveness to the image receiving layer. Examples of such compounds include silicone resins such as silicone oil; fluorine resins such as Teflon (registered trademark) and fluorine-containing acrylic resins; polysiloxane resins; acetal resins such as polyvinyl butyral, polyvinyl acetal and polyvinyl formal; Solid waxes such as waxes and amide waxes; and fluorine-based and phosphate-based surfactants. As a method of forming the release layer,
A material obtained by dissolving the material in a solvent or dispersing in a latex state is a blade coater, a roll coater, a bar coater,
A coating method such as a curtain coater or a gravure coater, an extrusion lamination method using a hot melt, or the like can be applied, and can be formed by coating on a cushion layer. Alternatively, there is a method in which a material obtained by dissolving or dispersing the material in a solvent or in the form of latex on a temporary base is applied by the above-described method and bonded to a cushion layer, and then the temporary base is peeled off.

The image-receiving sheet combined with the thermal transfer sheet may have a structure in which the image-receiving layer also serves as a cushion layer. / Cushioning image receiving layer may be used. Also in this case, it is preferable that the cushioning image-receiving layer is provided in a releasable manner so that the image can be retransferred 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 cushioning image receiving layer is 5 to 100 μm, preferably 10 to 100 μm.
４０40 μm.

It is preferable to provide a back layer on the surface of the support opposite to the surface on which the image receiving layer is provided, since the transportability of the image receiving sheet is improved. It is preferable to add 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 in terms of improving the transportability in the recording apparatus. The additives can be added not only to the back layer but also to the image receiving layer and other layers as needed. Although the type of additive cannot be specified unconditionally 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 to the layer in an amount of about 0.5 to 80%. As the antistatic agent, the surface resistance of the layer is 23 ° C., 50
% 10 ¹² Omega less RH for, more preferably 10 ⁹ Omega
As described below, it can be appropriately selected and used from various surfactants and conductive agents.

Examples of the binder used for the back layer include gelatin, polyvinyl alcohol, methyl cellulose, nitrocellulose, acetyl cellulose, aromatic polyamide resin, silicone resin, epoxy resin, alkyd resin, phenol resin, melamine resin, fluorine resin, and polyimide resin. , Urethane resin, acrylic resin, urethane modified silicone resin, polyethylene resin, polypropylene resin, polyester resin, Teflon resin, polyvinyl butyral resin, vinyl chloride resin, polyvinyl acetate, polycarbonate, organic boron compounds, aromatic esters, fluorinated polyurethane A general-purpose polymer such as polyether sulfone can be used. Cross-linking using a cross-linkable water-soluble binder as the binder for the back layer is effective in preventing the matting agent from falling off and improving the scratch resistance of the back layer. It is also highly effective in blocking during storage. This cross-linking means can employ any one or combination of heat, actinic rays, and pressure without particular limitation, depending on the characteristics of the cross-linking agent used. In some cases, an optional adhesive layer may be provided on the side of the support on which the back layer is provided, in order to impart adhesiveness to the support.

Organic or inorganic fine particles can be used as the matting agent preferably added to the back layer. As an organic matting agent, polymethyl methacrylate (PMM
A), polystyrene, polyethylene, polypropylene,
Other examples include fine particles of a radical polymerizable polymer, and fine particles of a condensation polymer such as polyester and polycarbonate. The back layer is preferably provided in a coverage of about 0.5 to 5 g / m ² . If it is less than 0.5 g / m ² , the coating properties are unstable and problems such as powder dropping of the matting agent tend to occur. Further, if the coating is applied in excess of 5 g / m ² , the particle size of the suitable matting agent becomes very large, and the embossing of the image receiving layer surface by the back layer occurs during storage. In particular, thermal transfer for transferring a thin image forming layer In this case, missing or unevenness of a recorded image is likely to occur. The matting agent preferably has a number average particle size that is larger by 2.5 to 20 μm than the layer thickness of the binder alone of the back layer. Among the matting agents, 5 mg / m ² or more of particles having a particle size of 8 μm or more is required, and preferably 6 to 60 μm.
0 mg / m ² . This improves, in particular, foreign object failure. Further, by using a material having a narrow particle size distribution such that a value σ / rn (= coefficient of variation of the particle size distribution) obtained by dividing the standard deviation of the particle size distribution by the number average particle size is 0.3 or less, Defects caused by particles having an unusually large particle size can be improved, and desired performance can be obtained with a smaller amount of addition. This coefficient of variation is more preferably 0.15 or less.

It is preferable to add an antistatic agent to the back layer in order to prevent adhesion of foreign matter due to frictional charging with the transport roll. Examples of the antistatic agent include cationic surfactants, anionic surfactants, nonionic surfactants, polymer antistatic agents, conductive fine particles, and “1129”.
Compounds described in Chemical Industry No. 0, pp. 875-876, etc. are widely used. As the antistatic agent that can be used in combination with the back layer, among the above substances, conductive fine particles such as carbon black, metal oxides such as zinc oxide, titanium oxide and tin oxide, and organic semiconductors are preferably used. In particular, the use of conductive fine particles is preferable because the antistatic agent does not dissociate from the back layer and a stable antistatic effect can be obtained regardless of the environment. In addition, the back layer, in order to impart coating properties and release properties, various activators,
It is also possible to add a release agent such as silicone oil or fluorine-based resin. The back layer is particularly preferable when the softening points of the cushion layer and the image receiving layer as measured by TMA (Thermomechanical Analysis) are 70 ° C. or less.

The TMA softening point is determined by raising the temperature of an object to be measured at a constant heating rate while applying a constant load, and observing the phase of the object. In the present invention, the TMA softening point is defined as the temperature at which the phase of the measurement object starts to change. The measurement of the softening point by TMA can be performed using a device such as Thermoflex manufactured by Rigaku Denki Co., Ltd.

The thermal transfer sheet and the image receiving sheet can be used for image formation as a laminate in which the image forming layer of the thermal transfer sheet and the image receiving layer of the image receiving sheet are overlapped. The laminate of the thermal transfer sheet and the image receiving sheet can be formed by various methods. For example, it can be easily obtained by stacking the image forming layer of the thermal transfer sheet and the image receiving layer 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. or lower.

As another method for obtaining a laminate, the above-described vacuum contact method is also suitably used. In the vacuum contact method, first, an 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 pressed while uniformly extruding air with a squeeze roller. This is a method in which the substrate is brought into close contact with a vacuum. 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.

[0127]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.
Unless otherwise noted in the text, “parts” means “parts by mass”,
“%” Means “% by mass”.

Examples 1 to 3 and Comparative Examples 1 and 2 -Preparation of Thermal Transfer Sheet- [Formation of Back Layer (Antistatic Layer)] 1) [Preparation of Coating Solution for Back First Layer] Aqueous dispersion of acrylic resin 2 Part (Julima ET410, solid content 20% by mass, manufactured by Nippon Pure Chemical Co., Ltd.) Antistatic agent (tin oxide-antimony oxide aqueous dispersion) 7.0 parts (average particle size: 0.1 μm, 17% by mass) Polyoxyethylene phenyl ether 0.1 part Melamine compound 0.3 part (Sumitic Resin M-3, manufactured by Sumitomo Chemical Co., Ltd.) Distilled water was prepared so that the total amount would be 100 parts [Formation of back first layer] 75 μm thick biaxially stretched polyethylene terephthalate support (Ra on both sides is 0.01 μm
m) is subjected to a corona treatment on one side (back side),
After applying 1 layer coating solution so that dry layer thickness is 0.03μm
After drying at 180 ° C. for 30 seconds, the first bag layer was formed. The Young's modulus of the support in the longitudinal direction is 450 kg / mm ² (≒ 4.
4 GPa) and the Young's modulus in the width direction is 500 kg / mm ^2.
(≒ 4.9 GPa). F-5 in the longitudinal direction of the support
The value was 10 kg / mm ² (≒ 98 MPa), and the F-5 value in the support width direction was 13 kg / mm ² (≒ 127.4 MPa).
The heat shrinkage of the support at 100 ° C. for 30 minutes is 0.3% in the longitudinal direction and 0.1% in the width direction. The breaking strength is 20 kg / mm ² (≒ 196 MPa) in the longitudinal direction.
The width direction is 25 kg / mm ² (≒ 245 MPa), and the elastic modulus is 400 kg / mm ² (≒ 3.9 GPa). 2) [Preparation of back layer second layer coating solution] Polyolefin 3.0 parts (Chemipearl S-120, 27% by mass, manufactured by Mitsui Petrochemical Co., Ltd.) Antistatic agent (tin oxide-antimony oxide aqueous dispersion) 2 0.0 parts (average particle size: 0.1 μm, 17% by mass) Colloidal silica 2.0 parts (Snowtex C, 20% by mass, manufactured by Nissan Chemical Co., Ltd.) Epoxy compound 0.3 parts (Dinacol EX-614B) , Nagase Kasei Co., Ltd.) Distilled water was prepared so that the total would be 100 parts. [Formation of back second layer] Apply coating solution of back second layer on top of first back layer so that dry layer thickness is 0.03 μm. 170 ° C after application
For 30 seconds to form a back first layer.

[Formation of Heat Insulating Layer] 4) Preparation of Coating Liquid for Heat Insulating Layer The following two kinds of coating liquids were prepared and used for forming the heat insulating layer.
(PVA-based): Prepared by adding 2 g of styrene-acrylic hollow particles SX-863P (manufactured by Nippon Shokubai Co., Ltd.) to 10 g of PVA-205 (Kuraray). (Gelatin type): It was prepared by adding 2 g of the hollow particles SX-863P (manufactured by Nippon Shokubai Co., Ltd.) to 10 g of lime-processed gelatin (Nitta Gelatin) (6 g was added in Comparative Example).

5) Formation of Heat Insulating Layer As shown in Table 1 below, in Example 2 and Comparative Example 2, a PVA-based coating solution was used, and in Example 3, a gelatin-based coating solution was used. . In other examples, no heat insulating layer was formed. The heat-insulating layer is formed by spin-coating the above-mentioned heat-insulating layer-forming coating solution on the surface of the 75 μm-thick polyethylene terephthalate film opposite to the back layer on which the back layer (antistatic layer) was formed in 3) above. After applying using a machine (wheeler), the applied material was placed in an oven at 100 ° C. for 2 hours.
After drying for a minute, a heat insulating layer was formed on the support.

[Formation of Light-to-Heat Conversion Layer] 6) Preparation of Light-to-Heat Conversion Layer-Forming Coating Solution The following components were heated with a stirrer and mixed while stirring to prepare a light-to-heat conversion layer-forming coating solution. (Composition of coating liquid) Methyl ethyl ketone 800 parts N-methyl-2-pyrrolidone 1200 parts Surfactant (F-177, manufactured by Dainippon Ink and Chemicals, Inc.) 1 part Infrared absorbing dye (NK-2014, Nippon Kogyo Dye Co., Ltd.) )) 10 parts Polyimide (Ricacoat SN-20, manufactured by Nippon Rika Co., Ltd.) 200 parts

7) Formation of a light-to-heat conversion layer on the surface of the support: 75 μm in thickness with the back layer (antistatic layer) formed in 3) above
m on the surface of the polyethylene terephthalate film opposite to the back layer, or on the surface of the heat insulating layer formed in 5) above, using a wire bar to apply the coating solution for the photothermal conversion layer. After drying in an oven at 2 ° C. for 2 minutes, a light-to-heat conversion layer was formed on the support. The optical density of the obtained photothermal conversion layer at a wavelength of 808 nm was measured with a spectrophotometer UV-240 manufactured by Shimadzu Corporation.
= 1.03. The layer thickness was 0.3 μm on average when the cross section of the photothermal conversion layer was observed with a scanning electron microscope.
Met.

[Formation of Image Forming Layer] 8) Preparation of Image Forming Layer Coating Solution The following four types of image forming layer coating solutions (A to D) were prepared.・ Polyvinyl butyral resin 12 parts (Denka Butyral # 2000-L, Vicat softening point 57 ° C., manufactured by Denki Kagaku Kogyo KK) ・ Pigment 15 pigments below Coating solution A: Cyan pigment (CI.P. ) Coating liquid B: Magenta pigment (CI.PR. 57: 1) Coating liquid C: Yellow pigment (CI.P.Y.14) Coating liquid D: Black pigment (MA-100, manufactured by Mitsubishi Chemical Corporation)・ Dispersing aid Solsperse S-20000 0.8 parts (manufactured by ICI Japan) ・ Solvent n-PrOH 110 parts

7) Formation of an image forming layer on the surface of the light-to-heat conversion layer-For each 10 parts of the coating liquids A, B, C and D, 0.24 parts of stearin amide Rosin resin (manufactured by Arakawa Chemical Co., Ltd.) Rosin KE311) 0.12 parts Polyvinyl butyral resin 0.4 parts Surfactant (F-177, manufactured by Dainippon Ink and Chemicals, Inc.) 0.045 parts n-prOH 100 parts was added to form a coating solution. The dry film thickness is 0.4 μm for A, 0.4 μm for B, C
Was applied so as to be 0.4 μm and in the case of D 0.35 μm.

Through the above steps, four types of thermal transfer sheets were prepared for each example, in which the light-to-heat conversion layer and the image forming layer were provided on the support in this order. In Examples 2 and 3 and Comparative Example 2, a heat insulating layer was provided between the support and the light-to-heat conversion layer. Hereinafter, the image forming layer which is a cyan image forming layer is a thermal transfer sheet C, the magenta image forming layer is a thermal transfer sheet M, and the yellow image forming layer is a thermal transfer sheet Y and a black image forming layer. Is referred to as a thermal transfer sheet K.

-Preparation of Image Receiving Sheet- 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-Vinyl chloride-vinyl acetate copolymer 20 parts (main binder) ("MPR-TSL", manufactured by Nissin Chemical Co., Ltd.)-Plasticizer 10 parts ("Paraplex G-40" , CP.HALL.COMPANY Co., Ltd.)-Surfactant (fluorine-based: coating aid) 0.5 parts ("Megafac F-177", manufactured by Dainippon Ink and Chemicals, Inc.)-Antistatic agent ( (Quaternary ammonium salt) 0.3 part ("SAT-5 Super (IC)", manufactured by Nippon Pure Chemical Co., Ltd.)-60 parts of methyl ethyl ketone-10 parts of toluene-3 parts of N, N-dimethylformamide

2) Coating Solution for Image-Receiving Layer 117 parts of polyvinyl butyral (binder) (“ESREC B BL-1”, manufactured by Sekisui Chemical Co., Ltd.) 63 parts of (binder) (Oxylac SH-128, -Nippon Shokubai Co., Ltd.-16 parts of antistatic agent ("Chemistat 3033", manufactured by Sanyo Chemical Industries, Ltd.)-1.2 parts of surfactant ("Megafac F-176PF", Dainippon Ink & Chemicals, Inc.)・ 570 parts of n-propyl alcohol ・ 1200 parts of methanol ・ 520 parts of 1-methoxy-2-propanol

Using a small width applicator, a white PET support (“Lumirror # 130E58”, manufactured by Toray Industries, Inc., thickness 1)
30 μm), the above-mentioned coating solution for forming a cushion layer is applied, the coating layer is dried, and then a coating solution for an image receiving layer is applied.
Dried. The thickness of the cushion layer after drying is about 20 μm,
The coating amount was adjusted so that the thickness of the image receiving layer was about 2 μm. The white PET support is a laminate of a void-containing polyethylene terephthalate layer (thickness: 116 μm, porosity: 20%) and titanium oxide-containing polyethylene terephthalate layers (thickness: 7 μm, titanium oxide content: 2%) provided on both sides thereof. (Total thickness: 130 μm, specific gravity: 0.8) is a void-containing plastic support. The produced image receiving sheet is wound up in a roll form, stored for 1 week at room temperature,
It was used for image recording by the following laser light.

-Formation of Transfer Image- The image-receiving sheet (56 cm × 79 cm) prepared above was placed on a rotating drum having a diameter of 38 cm having a vacuum section hole (one area density in an area of 3 cm × 8 cm) having a diameter of 1 mm. )
Vacuum adsorbed. Next, the thermal transfer sheet K (black) cut into a size of 61 cm × 84 cm was overlapped so as to protrude evenly from the image receiving sheet, and squeezed by a squeeze roller, and adhered and laminated so that air was sucked into the section holes. The degree of pressure reduction with the section hole closed is -150 mmHg (１５０8
1.13 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 spot of 7 μm 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 11mW Drum rotation speed 500rpm Sub-scanning pitch 6.35μm Ambient temperature and humidity 18 ° C 30%, 23 ° C 50%, 2
Three Conditions of 6 ° C. and 65% The diameter of the exposure drum is preferably 360 mm or more, and specifically, the one having 380 mm was used. The image size is 5
The size is 15 mm × 728 mm and the resolution is 2600 dpi. The laminated body after the laser recording was removed from the drum, and the thermal transfer sheet K was peeled off from the image receiving sheet by hand. It was confirmed that it was.

In the same manner as described above, the thermal transfer sheet Y,
From each of the thermal transfer sheets M and C, an image was transferred onto an image receiving sheet. The transferred four-color image was further transferred to recording paper to form a multi-color image.
Even when laser recording was performed with high energy using a laser beam having a dimensional array, a multicolor image having good image quality and a stable transfer density could be formed. For the transfer to the paper, a thermal transfer device having a dynamic friction coefficient of 0.1 to 0.7 with respect to polyethylene terephthalate of the material of the insertion table and a transport speed of 15 to 50 mm / sec was used. The Vickers hardness of the heat roll material of the thermal transfer device is preferably 10 to 100, and specifically, a Vickers hardness of 70 was used. The obtained image was good in all three environmental humidity.

The sensitivity at which an image was formed on the image forming layer of the thermal transfer sheet, the resolving power of the image, and the integration of the thermal transfer sheet were evaluated by the following methods. Further, the ratio (I / I _O ) of the non-diffusive transmittance (I) to the total light transmittance (I _O ) of the layer composed of the antistatic layer and the support, and in some cases, the heat insulating layer of the thermal transfer sheet, Was measured by the following method, and shown in Table 1. Sensitivity: One laser beam was recorded and evaluated at 150 times magnification using an optical microscope. ◎: Good recording without interruption of the main line. ： １: Recording without interruption of the main line. Δ: The main line was partially interrupted. X: The main line was entirely interrupted. Resolution: The resolution of the formed image was visually evaluated according to the following criteria. ：: Good resolution was obtained in use. ○: Sufficient resolution was obtained in use. △: Degree of resolution was obtained without any inadequacy in use. ×: Resolution inadequate in use.・ Integration: 18 ° C./30% RH and 27
Twenty sheets of A3 size were integrated under a temperature of 70 ° C./70% RH. ◎: All 20 sheets were satisfactorily integrated. ：: Somewhat stuck, but not a problematic level. ×: Poor integration.-The back side of the I / I _O thermal transfer sheet was 808 nm, manufactured by Shimadzu Corporation. It was measured with a spectrometer UV-240. -Surface specific resistance Measured according to the method described in JIS 2151 (1990).

[0142]

[Table 1]

The following is clear from Table 1. The thermal transfer sheet of the present invention (Examples 1 to 3) is excellent in sensitivity, resolution and integration. On the other hand, the ratio (I / I _O ) of the non-diffused transmittance (I) to the total light transmittance (I _O ) of the layer composed of the antistatic layer and the support exceeds 0.8, but the antistatic layer is provided. In the case of Comparative Example 1, which is not performed, the integration is inferior. The ratio of the non-diffused transmittance (I) to the total light transmittance (I _O ) of the layer comprising the heat insulating layer, the antistatic layer and the support (I / I _O ) is less than 0.7, and the antistatic layer In the case of Comparative Example 2 having no
Poor in these properties.

[0144]

According to the thermal transfer sheet of the present invention, when applied to a multicolor image forming method utilizing ablation, a high-sensitivity, high-quality image can be formed on the image forming layer, and the integration property is improved. Because it is excellent, there are few process problems. Further, the multicolor image forming method using the thermal transfer sheet having the above-mentioned excellent performance of the present invention can provide a contract proof that replaces proof printing and an analog color proof, for example, corresponding to filmless in the CTP era,
This proof can reproduce color reproducibility consistent with printed matter and analog color proof for customer approval.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a mechanism of forming a multicolor image by thin-film thermal transfer using a laser.

FIG. 2 is a diagram illustrating a configuration example of a recording apparatus for laser thermal transfer.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 recording device 2 recording head 3 sub-scanning rail 4 recording drum 5 thermal transfer sheet loading unit 6 image receiving sheet roll 7 transport roller 8 squeeze roller 9 cutter 10 thermal transfer sheet 10K, 10C, 10M, 10Y thermal transfer sheet roll 12 support 14 photothermal conversion layer Reference Signs List 16 image forming layer 20 image receiving sheet 22 support for image receiving sheet 24 image receiving layer 30 laminated body 31 discharge table 32 waste port 33 discharge port 34 air 35 waste box

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B41M 5/40 B41M 5/26 GFQS

Claims (6)

[Claims] 1. A thermal transfer sheet having a light-to-heat conversion layer and an image forming layer provided in this order on one surface of a support, and an antistatic layer provided on the opposite surface, wherein the antistatic layer and the support are provided. Total light transmittance (I _O ) of the layer consisting of
Ratio (I / I _O ) of the non-diffuse transmittance (I) to
A thermal transfer sheet having a light wavelength of 0.8 or more in a light wavelength range of 00 to 900 nm. 2. A thermal transfer sheet comprising a support having a light-to-heat conversion layer and an image forming layer provided in this order on one surface and an antistatic layer provided on the opposite surface, wherein the support and the light-to-heat conversion layer are provided. And a ratio of the non-diffused transmittance (I) to the total light transmittance (I _O ) of the layer comprising the heat insulating layer, the antistatic layer and the support (I /
(I _O ) is 0.7 or more in a light wavelength range of 400 to 900 nm. 3. The image forming layer has a surface resistivity of 1 × 10 ¹⁵ Ω measured in an environment at a temperature of 23 ° C. and a relative humidity of 50%.
/ Sq or less, and the surface resistivity on the antistatic layer side is 1 ×
The thermal transfer sheet according to claim 1, wherein the thermal transfer sheet has a resistivity of 10 ⁹ Ω / sq or less. 4. An image forming layer having a thickness of 0.1 to 1.5 μm, and a pigment and an amorphous organic high molecular polymer having a softening point of 40 to 150 ° C. The thermal transfer sheet according to any one of claims 1 to 3, wherein the thermal transfer sheet is contained in a mass ratio (pigment / polymer) of / 30. 5. A photothermal conversion type image forming material comprising a combination of the thermal transfer sheet according to claim 1 and an image receiving sheet having at least an image receiving layer on a support. 6. An image receiving sheet having an image receiving layer on a support, and yellow, magenta, cyan and black having at least a photothermal conversion layer and an image forming layer on the support.
Using a different type of thermal transfer sheet, the image forming layer of each thermal transfer sheet and the image receiving layer of the image receiving sheet are superposed facing each other, and irradiated with laser light, and the laser light irradiated area of the image forming layer is received by the image receiving sheet. A multicolor image forming method comprising a step of transferring an image onto a layer and recording an image, wherein the thermal transfer sheet is the thermal transfer sheet according to any one of claims 1 to 4. Method.