JP2002347357A - Thermal transfer sheet and method for forming multicolor image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal transfer sheet which has excellent light resistance without hue change of a recording image and no image quality deterioration in a method for forming a multicolor image using a laser beam irradiation, and to provide the method for forming the multicolor image using the same. SOLUTION: The thermal transfer sheet comprises a photothermal conversion layer having a ratio (ODLH/TLH) of an optical density (ODLH) to a layer thickness (TLH μm) of 0.57 or more and an image forming layer on a support. The transfer sheet records the image by oppositely superposing the image forming layer and the image receiving layer of the image receiving sheet, irradiating the superposed layers with the laser beam, and transferring the laser beam irradiated region of the image forming layer onto the image receiving layer. In this transfer sheet, as a photothermal conversion substance of the conversion layer, a dye having a specific structure is used. The method for forming the multicolor image uses the thermal transfer sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a thermal transfer sheet and a multicolor image forming method capable of forming a high-resolution full-color image using a laser beam. In particular, the present invention relates to color proofing (DDCP: direct
(Digital color proof) or a thermal transfer sheet useful for producing a mask image, and a multicolor image forming method using the thermal transfer sheet.

[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 high 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 and generates heat, a wax having a heat-fusible pigment, a binder, etc. are provided on a support. Heat-melt transfer sheet having an image forming layer dispersed in the components
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]

In such a multicolor image forming method, an infrared-absorbing dye as a light-to-heat converting substance is transferred to an image forming layer when a thermal transfer sheet is prepared or stored, so that the hue is reduced. And deterioration of image quality such as deterioration of light fastness. In addition, degradation of the infrared absorbing dye after laser recording is transferred to the transfer receiving body together with the image forming layer, resulting in the same deterioration in image quality. SUMMARY OF THE INVENTION An object of the present invention is to provide a multicolor image forming method using laser light irradiation, and to provide a thermal transfer sheet which is excellent in light resistance without a change in hue of a recorded image and does not cause deterioration in image quality. It is another object of the present invention to provide a method for forming a multicolor image by irradiating a laser beam which does not change the hue of a recorded image, has excellent light fastness, and does not cause deterioration in image quality.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object. As a result, to prevent the deterioration of the image quality due to the migration of the infrared absorbing dye itself or the decomposition product thereof, a photothermographic method was used. The inventors have found that it is effective to use a dye having a specific structure as a conversion substance, and have reached the present invention.
According to the present invention, a thermal transfer sheet and a multicolor image forming method having the following configurations are provided, and the above object of the present invention is achieved. 1. Optical density (OD _LH ) and layer thickness (T _LH μm) on the support
At least a light-to-heat conversion layer and an image forming layer having a ratio (OD _LH / T _LH ) of 0.57 or more. Irradiating the laser light irradiation area of the image forming layer onto the image receiving layer of the image receiving sheet to record an image, wherein the light-to-heat conversion material of the light-to-heat conversion layer, the following general A thermal transfer sheet characterized by being a compound represented by the formula (1).

[0009]

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Wherein Z is a benzene ring, a naphthalene ring or
Represents an atomic group for forming a heteroaromatic ring. T is
O, S, Se, N (R¹), C (R^Two) (R^Three) Or C
(R^Four) = C (R ^Five). Where R¹, R^TwoAnd R^Three
Each independently represents an alkyl group, an alkenyl group, or an
Represents a reel group. R^FourAnd R^FiveAre each independently a hydrogen source
, Halogen atom, alkyl group, aryl group, alkoxy
Group, aryloxy group, carboxyl group, acyl group,
Acylamino, carbamoyl, sulfamoyl, etc.
Or a sulfonamide group. L is 5 or 7
3 resulting from the methine group of
Represents a valent linking group. M represents a divalent linking group. X
^-Represents an anion. 2. The resolution of the recorded image is 2000 dpi or more
2. The thermal transfer sheet according to the above item 1, wherein 3. Optical density of image forming layer (OD_I) And layer thickness (T_Iμm)
And the ratio (OD_I/ T_I) Is 1.80 or more
3. The thermal transfer sheet as described in 1 or 2 above. 4. An image receiving layer in which the contact angle of the image receiving layer with water is 90 ° or less.
The above, which is used in combination with a sheet
The thermal transfer sheet according to any one of 1 to 3, above. 5. An image receiving sheet having an image receiving layer, and at least
Also has a light-to-heat conversion layer and an image forming layer.
At least 4 types of thermal transfer of black, cyan and black
Sheet and the image forming layer of each thermal transfer sheet and the image receiving system.
The image transfer layer of the heat transfer sheet is
By irradiating laser light from the support side, the laser beam
Transfer the laser light irradiation area onto the image receiving layer of the image receiving sheet
A multicolor image forming method having a recording step, wherein each of the thermal transfer sheets is a heat transfer sheet according to any one of the above (1) to (4).
A multicolor image forming method, which is a transfer sheet.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a compound (dye) represented by the above general formula (1) is used as a photothermal conversion material of a photothermal conversion layer of a thermal transfer sheet used in the multicolor image forming system of the present invention. Can be By using the compound represented by the general formula (1) as the light-to-heat conversion material of the light-to-heat conversion layer of the heat transfer sheet, the compound does not migrate to the image forming layer when the heat transfer sheet is prepared or stored. The problems of image quality deterioration such as hue change and light fastness which have occurred conventionally do not occur, and the image quality deterioration due to the transfer of the decomposed product of the infrared absorbing dye after laser recording to the image receiving layer together with the image forming layer. No problem.

In the general formula (1), examples of the ring completed by Z include a benzene ring, a naphthalene ring, a pyridine ring, a quinoline ring, a pyrazine ring, a quinoxaline ring and the like. Further, on Z, another substituent R
⁶ may be combined. As such a substituent R ⁶ ,
For example, alkyl group, aryl group, heterocyclic residue, halogen atom, alkoxy group, aryloxy group, alkylthio group, arylthio group, alkylcarbonyl group, arylcarbonyl group, alkyloxycarbonyl group, aryloxycarbonyl group, alkylcarbonyloxy group , Arylcarbonyloxy group, alkylamide group, arylamide group, alkylcarbamoyl group, arylcarbamoyl group, alkylamino group, arylamino group, carboxylic acid group, alkylsulfonyl group, arylsulfonyl group, alkylsulfonamide group, arylsulfonamide And various substituents such as an alkylsulfamoyl group, an arylsulfamoyl group, a cyano group, and a nitro group. The number (p) of the substituents bonded on Z is usually preferably 0 or about 1 to 4. When p is 2 or more, a plurality of R ⁶ may be the same or different.

Among the substituents represented by R ⁶ , a halogen atom (for example, F, Cl, etc.), a cyano group, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms (for example,
A methoxy group, an ethoxy group, a dodecyloxy group, a methoxyethoxy group, etc., a substituted or unsubstituted phenoxy group having 6 to 20 carbon atoms (for example, phenoxy group, 3,5-
Dichlorophenoxy group, 2,4-di-t-pentylphenoxy group, etc.), substituted or unsubstituted carbon atoms having 1 to 2 carbon atoms.
0 alkyl group (for example, methyl group, ethyl group, isobutyl group, t-pentyl group, octadecyl group, cyclohexyl group, etc.), substituted or unsubstituted phenyl group having 6 to 20 carbon atoms (for example, phenyl group, 4 -Methylphenyl group, 4-trifluoromethylphenyl group, 3,5-dichlorophenyl group, etc.) and the like.

T is O, S, Se, N (R¹), C
(R^Two) (R^Three) Or C (R^Four) = C (R ^Five). This
In the case of R¹, R^Two, R^Three, R^FourAnd R^FivePreferred represented by
Groups include substituted or unsubstituted alkyl groups,
A reel group and an alkenyl group.
Is preferred. R¹ ~ R^FiveHas 1 carbon atom
To 30 are preferable, and 1 to 20 are particularly preferable.

When the groups represented by R ^{1 to} R ⁵ further have a substituent, examples of the substituent include a sulfonic acid group, an alkylcarbonyloxy group, an alkylamide group, an alkylsulfonamide group, and an alkoxy group. Preferred are carbonyl, alkylamino, alkylcarbamoyl, alkylsulfamoyl, alkoxy, aryloxy, alkylthio, arylthio, alkyl, aryl, carboxyl, halogen, cyano, and the like.

Among these substituents, a halogen atom (eg, F, Cl, etc.), a cyano group, a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms (eg, a methoxy group, an ethoxy group, a dodecyloxy group) Methoxyethoxy group), a substituted or unsubstituted phenoxy group having 6 to 20 carbon atoms (for example, phenoxy group, 3,5-di-
Chlorophenoxy group, 2,4-di-t-pentylphenoxy group, etc.), substituted or unsubstituted carbon atoms having 1 to 20 carbon atoms
(For example, a methyl group, an ethyl group, an isobutyl group, a t-pentyl group, an octadecyl group, a cyclohexyl group, etc.) or a substituted or unsubstituted phenyl group having 6 to 20 carbon atoms (for example, a phenyl group, A methylphenyl group, a 4-methylphenyl group, a 4-trifluoromethylphenyl group, a 3,5-dichlorophenyl group, etc.) are particularly preferred. R ^{1 to} R ⁵ are most preferably an unsubstituted alkyl group having 1 to 8 carbon atoms, and T is —C (CH
₃ ) _2- is particularly preferred.

L in the general formula (1) represents 3 or 5 formed by linking 5 or 7 methine groups by a conjugated double bond.
Represents a valent linking group and may be substituted. That is, L
Represents a pentamethine group or a heptamethine group generated by connecting a methine group by a conjugated double bond, and specifically, groups represented by the following (L-1) to (L-6) are preferable.

[0018]

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Among the above specific examples, (L-2) and (L-
The linking groups forming tricarbocyanines exemplified as 3), (L-4), (L-5) and (L-6) are particularly preferred. In the above formulas (L-1) to (L-6), Y
Represents a hydrogen atom or a monovalent group. Examples of the monovalent group represented by Y include a lower alkyl group (eg, a methyl group), a lower alkoxy group (eg, a methoxy group), a substituted amino group (eg, a dimethylamino group, a diphenylamino group, a methylphenylamino group, a morpholino group, Imidazolidine group, ethoxycarbonylpiperazine group, etc., alkylcarbonyloxy group (acetoxy group, etc.), alkylthio group (methylthio group, etc.), diano group, nitro group, halogen atom (Br, C
1, F, etc.) are preferred.

Particularly preferred among the groups represented by Y are hydrogen atoms, and particularly preferred among R ⁷ and R ⁸ are a hydrogen atom and a lower alkyl group (eg, a methyl group). In the above (L-4) to (L-6), i is 1 or 2, and j is 0 or 1.

M in the general formula (1) represents a divalent linking group, preferably a substituted or unsubstituted carbon atom having 1 to 2 carbon atoms.
Represents an alkylene group of 0. Examples include an ethylene group, a propylene group, and a butylene group.

X ⁻ in the general formula (1) supplies a necessary number of anions to neutralize the charge of the cation portion, and represents a monovalent or divalent anion. The X ^{-
The, C1 -, Br -, I} - halogen ions such, S
Alkyl sulfate ions such as O ²⁻ , HSO ⁻ , CH ₃ OSO ₃ ⁻ , paratoluenesulfonic acid ion, naphthalene-1,
5 Jisuhon acid ion, methanesulfonate ion, trifluoromethanesulfonate ion, octane sulfonate ion, p- chlorobenzoic acid ion, trifluoroacetate ion, oxalate ion, a carboxylate ion and succinic acid ion, PF ₆ ^- , BF ₄ ⁻ , C 1 O ₄ ⁻ , IO ₄ ⁻ , heteropolyacid ions such as tungstate ions and tungstophosphate ions, and phenolate ions such as H ₂ PO ₄ ⁻ , NO ⁻ and picrate ions. Among them, C1
^-, Br ^-, I ^- halogen ions such, CH ₃ OSO ₃ ^-, C
₂ H ₅ OSO ₃ ^-, p-toluenesulfonate ion, trifluoromethanesulfonate ion, p- chlorobenzene sulfonic acid ion, methanesulfonate ion, butane sulfonic acid ions, naphthalene-1,5-disulfonic acid ion, trifluoromethanesulfonic acid Perfluorosulfonic acid ions such as ions, PF ⁻ , BF ⁻ , C1O ^{− and the} like are more preferable, and among them, trifluoromethanesulfonic acid ion, PF ₆ ⁻ , C1O ₄ ^{− and the} like are particularly preferable.

Preferred specific examples of the compound represented by the general formula (1) are described below.

[0024]

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[0025]

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[0026]

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Next, the multicolor image forming method (system) of the present invention including the thermal transfer sheet of the present invention will be described in detail. Thus, the layer structure, composition, preparation method and the like of the thermal transfer sheet of the present invention will be described in detail.

According to the present invention, a thermal transfer image with sharp halftone dots is realized, and the paper transfer and the B2 size recording (515
mm × 728mm, but B2 size is 543mm ×
765 mm). This thermal transfer image can be a halftone image corresponding to the number of printing lines at a resolution of 2000 dpi or more, preferably 2400 to 2540 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 that of the image setter or the CTP setter, and to reproduce halftone dots and gradations with good print similarity.

In addition, since the thermal transfer image has a sharp halftone dot shape, it can faithfully reproduce a halftone dot corresponding to a laser beam. Further, since the recording characteristics have very small environmental temperature and humidity dependence, the thermal transfer image has a wide range of temperature and humidity environments. 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 reproducibility, so that a highly accurate CMS (color management system) can be realized. Also, this thermal transfer image is a Japanese color, SW
The hue such as the OP color, that is, the hue of the printed matter can be substantially matched, and the color appearance when the light source such as a fluorescent lamp or an incandescent lamp is changed can show the same change as the printed matter.

In this thermal transfer image, since the dot shape is sharp, fine lines of fine characters can be reproduced clearly.
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 when the film is thin, deformation or destruction easily occurs. 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 characteristics and a heat-resistant binder such as polyimide.

In general, when the light-to-heat conversion layer is deformed or the image forming layer itself is deformed by 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. , Resulting in an uneven image and a reduced apparent transfer density. 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 sharpness and sensitivity of the dots are maintained. In addition, transfer unevenness can be improved.

Generally, low-melting substances such as waxes are
There is a tendency to seep or crystallize on the surface of the image forming layer,
In some cases, a problem may occur in the image quality or the temporal stability of the thermal transfer sheet. In order to cope with this problem, it is preferable to use a low melting point substance having a small difference in Sp value from the polymer of 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 as described in JP-A-8-238858, and crosslinking two or more hydroxyl groups with a hardener.

Usually, at the time of printing by laser exposure, heat of about 500 ° C. or more is also applied to the image forming layer, and some pigments conventionally used are thermally decomposed. This can be prevented by adopting it in the image forming layer. When the infrared absorbing dye migrates from the light-to-heat conversion layer to the image forming layer due to high heat at the time of printing, the infrared ray represented by the above-described general formula (1) is prevented in order to prevent the hue from changing. It is preferable to design the light-to-heat conversion layer with a combination of an absorbing dye / binder.
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 use, 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 adhesion 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 that uniform unevenness is provided on the thermal transfer sheet so that the air can be flowed well and uniform clearance can be obtained.

As a method of forming irregularities on the thermal transfer sheet, there are generally post-treatments such as embossing and the addition of a matting agent to the coating layer. . 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 apparatus 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 to 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 this apparatus, it is assumed that a large number of sheets having a large area of B2 size can be stacked and stacked on the 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 is returned 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 are returned 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 from below the discharge port 33 to enable stacking of a plurality of sheets.

A transport roller 7 at any of a supply portion and a transport portion 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, and 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 contacting 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 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
The hardness is a hardness obtained by applying a static load to a 6-degree square quadrangular pyramidal diamond indenter, and the Vickers hardness Hv is obtained by the following equation. Hv = 1.854P / d ² (kg / mm ² ) ≒ 18.169
2P / d ² (MPa) where P: load magnitude (kg), d: diagonal length of square of recess (mm)

In the present invention, the elasticity at 20 ° C. of the adhesive material used in the above-mentioned adhesive roll is 200 kg / cm ² (≒ 19.6 MPa) or less. This is preferable because certain dust can be sufficiently removed and image defects can be suppressed.

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 thereof 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. The average surface of a portion extracted from the curved surface of the roughness by a reference area is used as a reference surface, and the highest to fifth peaks are determined. 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 probe-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, image defects can be prevented in combination with the above-described cleaning means, transport jams can be eliminated, and dot gain stability can be further improved.

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

The glossiness largely 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 for use as an image forming layer for uniform and high-definition images, but high smoothness results in greater resistance during conveyance, and the two 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.

Next, the outline of the mechanism of forming a multicolor image by thin-film thermal transfer using a laser will be described with reference to FIG. 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 of the thermal transfer sheet 10 is prepared. . The thermal transfer sheet 10 includes the support 1
2, on it, the light-to-heat conversion layer 14, and further thereon
The image receiving layer 20 includes an image forming layer 16 and a support 22.
And an image receiving layer 24 thereon, and the image receiving layer 24 is laminated on the surface of the image forming layer 16 of the thermal transfer sheet 10 so as to be in contact with the surface (FIG. 1A). When the laser light is radiated imagewise in time from the support 12 side of the thermal transfer sheet 10 of the laminate 30, the laser light irradiated area of the photothermal conversion layer 14 of the thermal transfer sheet 10 generates heat, and the image forming layer 16 is heated.
And the adhesive strength with the film is reduced (FIG. 1B). After that, 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 becomes
0 is transferred onto the image receiving layer 24 (FIG. 1C).

In forming 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 zero. .2μm or more and 0.5μm
It is preferably less than. The yellow, magenta,
When the 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.
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 kinds 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, the coloring power of PVC described in JP-A-10-140033 is disclosed.
Blackness and the like. PVC blackness refers to the addition of carbon black to a PVC resin, dispersion and sheeting by 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 mixed with LDPE (low density polyethylene) resin, and the mixture is 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.

Conditions for preparing diluted compound LDPE resin 58.3 g Calcium stearate 0.2 g Carbon black 40 mass% compounded resin 1.5 g A sheet with a slit width of 0.3 mm was formed. 65 ± 3μm
Into a film.

As a method of forming a multicolor image, as described above, the thermal transfer sheet is used to repeatedly overlap a 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, perform laser light irradiation according to a digital signal based on the image, and subsequently, peel off the thermal transfer sheet and the image receiving sheet, color separation images of each color on each image receiving sheet Are formed independently. Next, each of the formed color separation images is
A multicolor 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 a laser beam into heat, transfer the image forming layer containing a pigment to an image receiving sheet using the thermal energy, and form an image on the image receiving sheet. If present, transfer pigment,
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. The thermal transfer recording using laser beam irradiation includes, for example, conventionally known melt-type transfer, transfer by ablation, sublimation-type transfer, and the like. 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 perform a step of transferring the image receiving sheet on which the image has been printed by the recording apparatus to the printing paper (hereinafter 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 matter from a plate making system (for example, Celebra manufactured by Fuji Photo Film Co., Ltd.), the system connection is as follows. CTP (Computer To Plate)
e) Connect the 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. The 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 colors match 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 apparatus 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 of the present invention, which are suitably used in the recording apparatus of the above system, will be described. [Thermal Transfer Sheet] The thermal transfer sheet of the present invention 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 of the present invention 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,
Synthetic resin materials such as polycarbonate, polymethyl methacrylate, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, styrene-acrylonitrile copolymer, polyamide (aromatic or aliphatic), polyimide, polyamideimide, and polysulfone Can be. 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 13
It is preferably 0 μm, 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 in the longitudinal direction and the width direction of the support at 100 ° C. for 30 minutes 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 (ｍｍ49 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 of the present invention is provided with a surface activation treatment and / or one or more undercoat layers to improve the adhesion to the light-to-heat conversion layer provided thereon. May be performed. Examples of the surface activation treatment include a glow discharge treatment and a corona discharge treatment. As a material for the undercoat layer, it has high adhesiveness to both surfaces of the support and the light-to-heat conversion layer, and has low thermal conductivity,
Further, it is preferable that the material has excellent heat resistance. Examples of such undercoat layer materials include styrene, styrene-
Butadiene copolymer, gelatin and the like can be mentioned. The thickness of the entire undercoat layer is usually from 0.01 to 2 μm.
Further, on the surface of the thermal transfer sheet opposite to the side on which the light-to-heat conversion layer is provided, various functional layers such as an anti-reflection layer and an anti-static layer can be provided or a surface treatment can be performed, if necessary.

(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 for 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.
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 for 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 in order 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.

In addition to the antistatic agent, various additives and binders such as a surfactant, a slip agent and a matting agent can be added to the first and second back layers. 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 80 parts by mass based on 100 parts by mass of the binder.
0 parts by mass is 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.

Examples of the binder used for forming the first and second back layers include 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, polyvinylbutyral, copolymer of vinyl compound such as polyvinyl alcohol and vinyl compound, polyester, polyurethane, polyamide Such condensation polymers, rubber-based thermoplastic polymers such as butadiene-styrene copolymers, polymers obtained by polymerizing or crosslinking photopolymerizable or thermopolymerizable compounds such as epoxy compounds, melamine compounds, and the like. .

(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, and generally includes a colorant (a dye and a pigment that can absorb laser light).
Hereinafter, the same applies. ). In the present invention in which an image is recorded by an infrared laser, as described above, the compound represented by the general formula (1) is used as a photothermal conversion material. Photothermal conversion materials other than those represented by the general formula (1) (hereinafter, referred to as “other photothermal conversion materials”) can be used without impairing the achievement of the object of the present invention. Examples of other light-to-heat conversion materials include black pigments such as carbon black, phthalocyanines, pigments of macrocyclic compounds having absorption in the visible to near-infrared region such as naphthalocyanine, and laser absorbing materials for high-density laser recording such as optical disks. Examples thereof 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. Further, as the other 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 coloring material.

The amount of the compound represented by the general formula (1) varies depending on the type of the specific compound. It is used in the range of 0.6 to 1.5.

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, when the resin is heat-resistant and does not decompose even by the heat generated from the light-to-heat conversion material, even if high-energy light irradiation is performed, the surface of the light-heat conversion layer after light irradiation can be smoothed. 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 temperature rising rate of 10 ° C./min.) Is preferably 400 ° C. or higher, and the resin having a thermal decomposition temperature of 500 ° C. or higher is preferable. 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, heat deformation temperature and thermal decomposition temperature) of the binder of the light-to-heat conversion layer is higher than that of 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 coating solution for the light-to-heat conversion layer are improved.

[0078]

Embedded image

In the above 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.

[0080]

Embedded image

[0081]

Embedded image

In the 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.

[0083]

Embedded image

[0084]

Embedded image

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 guide for judging whether or not the resin is soluble in an organic solvent, at 25 ° C.,
Based on the dissolution of 10 parts by mass or more based on 100 parts by mass of methylpyrrolidone, the case of dissolving 10 parts by mass or more is preferably used as a resin for a light-to-heat conversion layer.
More preferably, the resin dissolves in 100 parts by mass or more based on 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 from 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.

When 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, since 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, it is 5 to 0.5 μm. Further, it is preferable that the light-to-heat conversion layer has an optical density of 0.80 to 1.26 with respect to light having a wavelength of 808 nm, which is a laser peak wavelength, because the transfer sensitivity of the image forming layer is improved. More preferably, it has an optical density of 0.92 to 1.15 for light having a wavelength. If the optical density at the laser peak wavelength is less than 0.80, 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 at the time of recording, and fog may occur.

(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. Just fine. When the thermal transfer sheet is used for printing color proofing, an organic pigment having a color tone similar to or close to yellow, magenta, cyan, and black generally used for printing ink is preferably used. In addition, a metal powder, a fluorescent pigment, or the like may be used. Examples of preferably used pigments include azo pigments, phthalocyanine pigments, anthraquinone pigments, dioxazine pigments, quinacridone pigments, isoindolinone pigments, and nitro pigments. The 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.)
Manufactured by Toyo Ink Mfg. Co., Ltd.), 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 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 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 Mfg. Co., Ltd.), Fastog
en Super Magenta RH (Dainippon Ink & Chemicals, Inc.)
Manufactured) 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 Mfg. 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 (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.)
Co., Ltd.), Lionogen Blue (Lionogen Blue) 6501 (manufactured by Toyo Ink Mfg. Co., Ltd.)

4) Black Pigment Pigment Black (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 average particle size of the pigment is 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, when the particle size is more than 1 μm, coarse particles in the pigment may cause the image forming layer and the image receiving layer to have a large size. In some cases, the adhesion may be impaired, and the transparency of the image forming layer may be impaired.

As the binder for the image forming layer, an amorphous organic high molecular polymer having a softening point of 40 to 150 ° C. is preferable. 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, homopolymers and copolymers of substituted products, 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 the pigment in an amount of 30 to 70% by mass, more preferably 30 to 50% by mass. In addition, the image forming layer is made of 70% resin.
The content is preferably from 30 to 30% by mass, more preferably from 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. Among them, 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 ) _n COOH 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 (eg, 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 ) _n OH In the above formula, n represents an integer of 6 to 28. Specific examples include stearyl alcohol.

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

The above-mentioned plasticizer may be a polymer. Among them, polyester is preferable because it has a large effect of addition and hardly diffuses 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, the 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 absorbing 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 or the like is prepared, and the solution is coated on the light-to-heat conversion layer (when 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.

The light-to-heat conversion layer and the image forming layer of the thermal transfer sheet of the present invention have been described above. Each of these layers further has the following characteristics. The light-to-heat conversion layer has a ratio (OD _LH ) between its optical density (OD _LH ) and the thickness of the light-to-heat conversion layer (T _LH μm).
_LH / _TLH ) is 0.57 or more, preferably 1.95 or more;
More preferably, it is controlled to 4.01 or more. OD _LH / T
_There is no particular upper limit for _LH , and the larger the value, the better.
At the moment, considering the balance with other characteristics, 10
Degree is the limit. The optical density (OD _LH ) is the absorbance of the light-to-heat conversion layer at a wavelength (peak wavelength) at which a peak appears in the intensity distribution of the laser beam used, and can be measured using a known spectrophotometer. In the present invention,
A UV-spectrophotometer UV-240 manufactured by Shimadzu Corporation was used.
The optical density (OD _LH ) is calculated as a value obtained by subtracting the value of the support alone from the value measured including the support.

OD _LH / T _LH is related to the thermal conductivity at the time of recording, and is an index that largely affects the sensitivity and the temperature and humidity dependence of recording. When the OD _LH / T _LH of the thermal transfer sheet of the present invention is within the above range, the transfer sensitivity to the image receiving sheet during recording can be increased, and the temperature and humidity dependency during recording can be reduced. That is, by increasing OD _LH / T _LH , the resolution of the transferred image is increased to 2000 dpi or more, preferably 2400 dpi or more, and more preferably 2600 dpi.
With the above resolution, and preferably with a recording area of 515 mm
× 728 mm or more, more preferably 594 × 841 mm
Images can be recorded in the above sizes. The light-to-heat conversion layer has a wavelength of 808 nm and a wavelength of 0.80 to 1.26 for improving the transfer sensitivity of the image forming layer.
OD _LH of 0.92-1.
More preferably, it has an OD _LH of 15. When the optical density at the laser beak wavelength is less than 0.80,
It may be 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 at the time of recording, and fog may occur. Further, the layer thickness of the light-to-heat conversion layer is 0.1 mm.
It is preferably from 0.3 to 1.0 μm, and from 0.05 to 0.1 μm.
More preferably, it is 5 μm.

The image forming layer of the thermal transfer sheet of the present invention
Optical density (OD_I) And the thickness of the image forming layer (T_Iμm) and
Ratio (OD_I/ T_I) Should be more than 1.5
More preferably 1.8 or more, and 2.50 or less
Above is particularly preferred. OD_I/ T_IThe upper limit of
It is preferable to be as large as possible.
Considering the balance with the characteristics, the limit is about 6.
○ D_I/ T_IIs the transfer density of the image forming layer and the resolution of the transferred image
Index of degree. OD _I/ T_IIs within the above range.
Image with high transfer density and good resolution
it can. Also, by making the image forming layer thinner
Color reproducibility can be improved. OD_IIs the thermal transfer system
The image transferred to the image receiving sheet from the
What was transferred to a paper sheet was transferred to a densitometer (X-lite93
8, X-rite), yellow (Y), magenta
(M), cyan (C) or black (K)
It refers to the reflection optical density obtained in the color mode.

The thickness of the image forming layer in the black thermal transfer sheet is larger than the thickness of the image forming layer in each of the yellow, magenta and cyan thermal transfer sheets.
And it is preferable that it is 0.5-0.7 micrometers. 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. By setting the thickness of the image forming layer in the black thermal transfer sheet to 0.5 μm or more, when recording with high energy, image density is maintained without transfer unevenness,
The required image density as a proof for printing can be achieved. This tendency becomes more remarkable under high humidity conditions, so that a change in concentration due to the environment can be suppressed. on the other hand,
By setting the layer thickness to 0.7 μm or less, transfer sensitivity can be maintained during laser recording, and small dots and fine lines can be improved. This tendency is more pronounced under low humidity conditions. In addition, the resolution can be improved. The thickness of the image forming layer in the black thermal transfer sheet is more preferably 0.55
To 0.65 μm, 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. .2 μm or more and 0.5 μm
It is preferably less than. Yellow, magenta,
By setting the thickness of the image forming layer in each of the thermal transfer sheets of cyan and cyan to 0.2 μm or more, the density can be maintained without transfer unevenness during laser recording. On the other hand, by setting the thickness to 0.5 μm or less, the transfer sensitivity and The resolution can be improved. More preferably, it is 0.3 to 0.45 μm.

Further, the contact angles of the image forming layer of each thermal transfer sheet and the image receiving layer of the image receiving sheet, which will be described in detail later, with water are 7.0 to 120.0 °, respectively.
It is preferable that The contact angle is an index relating to the compatibility between the image forming layer and the image receiving layer, that is, the transferability, and is more preferably 30.0 to 100.0 °. Further, the contact angle of the image receiving layer with water is more preferably 90 ° or less. Setting the contact angle in the above range is preferable in that the transfer sensitivity can be increased and the dependence of recording characteristics on temperature and humidity can be reduced. The contact angle of each layer surface with water was measured using a contact angle meter (Contact).
(Angle Meter) CA-A type (manufactured by Kyowa Interface Science Co., Ltd.).

In another embodiment, the ratio (OD _I / T _I ) between the optical density (OD _I ) and the layer thickness (T _I μm) of the image forming layer of the thermal transfer sheet is set to 1.80 or more. preferable.
When the thickness is in the above range, the concealing power of the upper layer is reduced by decreasing the film thickness, so that the reproducibility of the secondary color and the tertiary color of the multicolor image is advantageous. It is also preferable to use the image receiving layer of the image receiving sheet in combination with a water contact angle of 90 ° or less, preferably 60 ° or less. By setting the content within the above range, the paper transferability is improved.

As described above, the OD _LH / T _LH of the light-to-heat conversion layer of the thermal transfer sheet of the invention, and the OD _I /
The T _I is in the above range, to form a recorded image on a large screen. The recording area of the multicolor image is preferably 515 m
The size is at least mx 728 mm, more preferably the size of the recording area of the multicolor image is at least 594 x 841 mm. The size of the image receiving sheet is preferably 465 × 68
The size is 6 mm or more.

(Thermal Release Layer) On the light-to-heat conversion layer of the thermal transfer sheet of the present invention, a gas is generated by the action of heat generated in the light-to-heat conversion layer, or adhered water or the like is released, whereby the light-to-heat conversion layer is released. A heat-sensitive release layer containing a heat-sensitive material that reduces the bonding strength between the resin and the image forming layer. Examples of such heat-sensitive materials include compounds (polymers or low-molecular compounds) that themselves 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 a low molecular compound). 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. In addition, the decomposition or deterioration of the heat-sensitive material due to heat as described above preferably occurs at 280 ° C. or lower, particularly preferably at 230 ° C. or lower.

When a low molecular compound is used as the heat-sensitive material of the heat-sensitive release layer, it is desirable to combine it with a binder. As the binder, the above-mentioned polymer which itself decomposes or degrades by heat to generate a gas can be used, but an ordinary 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.

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 adheres to the image forming layer and appears on the surface of the 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, so that the light-to-heat conversion layer and the heat-sensitive release layer also function. 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.
The method described in paragraph (0011) of the specification is followed. The smoother value of the surface of the image forming layer is 0.5 to 50 mmHg at 23 ° C. and 55% RH (℃ 0.0665 to 6.65 kP
a) is preferable, and Ra is preferably 0.05 to 0.4 μm. This makes it possible to reduce a large number of micro voids where the image-receiving layer and the image-forming layer cannot contact each other on the contact surface. Further, it is preferable in terms of image quality. The Ra value is measured by a surface roughness measuring device (Surfcom, Tokyo Seiki Co., Ltd.)
And the like can be measured based on JIS B0601. The surface hardness of the image forming layer is 1 with a sapphire needle.
It is preferably 0 g or more. After the thermal transfer sheet was charged according to US Federal Government Test Standard 4046, the charge potential of the image forming layer was -100 seconds after the thermal transfer sheet was grounded.
It is preferable that it is 100V. The surface resistance of the image forming layer is preferably 10 ⁹ Ω or less at 23 ° C. and 55% RH.

Next, an image receiving sheet that 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 necessary, any 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 from the viewpoint of transportability that a back layer is provided on the surface of the support opposite to the image receiving layer.

(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 may be, for example, a thermoplastic resin, a mixed melt obtained by mixing a filler made of an inorganic pigment or a polymer incompatible with the thermoplastic resin or the like, 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 polyolefin resin or the 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 diameter 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. still,
The content of the filler such as an inorganic pigment in the support is generally about 2 to 30% by volume.

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) It is preferable to provide one or more image-receiving layers on a support in order to transfer and fix the image-forming layer on the surface of the image-receiving sheet. 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 of acrylic monomers such as methacrylic esters and copolymers thereof, methyl cellulose, ethyl cellulose, cellulose polymers such as cellulose acetate, polystyrene, polyvinylpyrrolidone, polyvinyl butyral, polyvinyl alcohol, polyvinyl chloride, etc. And homopolymers and copolymers of vinyl monomers such as polyesters, condensation polymers such as polyesters and polyamides, and rubber polymers such as butadiene-styrene copolymers.
The binder of the image receiving layer is preferably a polymer having a glass transition temperature (Tg) lower than 90 ° C. in order to obtain a proper adhesive strength with the image forming layer. For this purpose, a plasticizer can be added 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. The binder polymer of the image receiving layer is the same as the binder polymer of the image forming layer, in that the adhesiveness with the image forming layer during laser recording is improved, and the sensitivity and the image strength are improved.
Or it is particularly preferable to use a similar polymer.

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 image receiving layer surface 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, at least one of the image receiving layers is preferably formed from 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 a 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 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. In addition, as the photopolymerization initiator, a general photoradical polymerization initiator such as benzophenone, Michler's ketone or the like is used in a ratio of 0.1 to 20% by mass in the layer.

The thickness of the image receiving layer is from 0.3 to 7 μm, preferably from 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 it is too thick, the gloss of the image after retransfer of the paper increases, and the closeness to the printed matter decreases.

The contact angle of the image receiving layer with water has already been described.

(Other layers) Between the support and the image receiving layer,
A cushion layer may be provided. When the cushion layer is provided, the adhesion between the image forming layer and the image receiving layer during laser thermal transfer can be improved, 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 to adjust these physical properties, for example, Tg.

Specific materials used as the binder for the cushion layer include rubbers such as urethane rubber, butadiene rubber, nitrile rubber, acrylic rubber, and natural rubber, as well as polyethylene, polypropylene, polyester, and styrene-butadiene copolymer. Copolymer, ethylene-vinyl acetate copolymer, ethylene-acryl copolymer, vinyl chloride-vinyl acetate copolymer, vinylidene chloride resin, vinyl chloride resin containing a plasticizer, polyamide resin, phenol resin and the like. Although the thickness of the cushion layer varies depending on the resin used and other conditions, it is usually 3 to 100 μm,
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. However, in order to transfer the image to the printing paper, it is preferable that the image receiving layer and the cushion layer are provided in a releasable manner. In order to facilitate peeling, it is also 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 the binder for the release layer is selected in accordance with the above physical properties, polycarbonate, acetal and ethyl cellulose are preferred in terms of storability, and 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.

If necessary, higher fatty acids, higher alcohols, higher fatty acid esters, amides, higher amines and the like can be added to such a release layer as additives.
Another configuration of the release layer is a layer that has a releasability by melting or softening during 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 configuration 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, a gravure coater, or the like, 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. In this case, the image receiving sheet may be a support / cushionable image receiving layer or a support / undercoat layer. / Cushioning image receiving layer may be used. Also in this case, it is preferable that the cushioning image-receiving layer is provided so as to be releasable so that it can be 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 above additives can be added not only to the back layer but also to the image receiving layer and other layers as necessary. Although the type of 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 Ω or less, more preferably 10 ⁹ Ω under the condition of% RH
As described below, it can be appropriately selected and used from various surfactants and conductive agents.

Examples of the binder used in 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.

As a matting agent preferably added to the back layer, organic or inorganic fine particles can be used. 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, when the coating is applied more than 5 g / m ² , the particle size of the suitable matting agent becomes extremely large, and the embossing of the image receiving layer surface by the back layer occurs during storage. 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 only the binder in 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 the 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 abnormally 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 of vacuum contact. 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 further applied and adhered to the metal drum while being mechanically pulled. 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.

[0147]

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

<Example 1> -Preparation of thermal transfer sheet K (black)-[Formation of back layer] [Preparation of coating liquid for back first layer]-Aqueous dispersion of acrylic resin 2 parts (Julima ET410, solid content 20) % By mass, manufactured by Nippon Junyaku Co., Ltd. ・ Antistatic agent (tin oxide-antimony oxide in water 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 would be 100 parts [Formation of first layer of back] 75 μm thick Biaxially stretched polyethylene terephthalate support (Ra on both sides is 0.0
(1 μm) is subjected to a corona treatment on one side (back side), and a coating liquid for the back first layer is applied so that the dry layer thickness becomes 0.03 μm, and then dried at 180 ° C. for 30 seconds to form a back first layer. did. The Young's modulus in the longitudinal direction of the support is 450 kg
/ Mm ² (≒ 4.4 GPa) and the Young's modulus in the width direction is 5
00 kg / mm ² (24.9 GPa). The F-5 value in the longitudinal direction of the support is 10 kg / mm ² (≒ 98 MP
a) The F-5 value in the width direction of the support is 13 kg / mm
² (≒ 127.4 MPa), 100 ° C.
The heat shrinkage in 30 minutes is 0.3% in the longitudinal direction and 0.1% in the width direction. The breaking strength is 20 kg / mm in the longitudinal direction.
² (≒ 196 MPa) and the width direction is 25 kg / mm ² (≒
245 MPa) and the elastic modulus is 400 kg / mm ² (≒ 3.
9 GPa).

[Preparation of Back 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 in water dispersion) Material) 2.0 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 part ( (Dinacol EX-614B, manufactured by Nagase Kasei Co., Ltd.) Distilled water was prepared to have a total of 100 parts. [Formation of back second layer]
The layer coating solution was applied to a dry layer thickness of 0.03 μm, and dried at 170 ° C. for 30 seconds to form a back first layer.

1) Preparation of Coating Solution for Light-to-Heat Conversion Layer The following components were mixed while stirring with a stirrer to prepare a coating solution for a light-to-heat conversion layer. [Composition of Light-to-Heat Conversion Layer Coating Solution] Light-to-heat conversion material (infrared absorbing dye) 8.0 parts (Specific example of compound of general formula (1) Compound 1)

-29.3 parts of a polyimide resin having the following structure ("Licacoat SN-20F", manufactured by Shin Nippon Rika Co., Ltd., thermal decomposition temperature: 510 ° C)

[0152]

Embedded image

(Wherein, R ₁ represents SO _2. R ₂ represents

[0154]

Embedded image

Is shown. Exonnaphtha 5.8 parts N-methylpyrrolidone (NMP) 1500 parts Methyl ethyl ketone 360 parts Surfactant 0.5 part Activator) ・ Mat agent dispersion of the following composition 14.1 parts

Matting agent dispersion liquid ・ N-methyl-2-pyrrolidone (NMP) 69 parts ・ Methyl ethyl ketone 20 parts ・ Styrene acrylic resin 3 parts (“Johncryl 611”, manufactured by Johnson Polymer Co., Ltd.) ・ SiO ₂ particles 8 parts ("Sea Hostar KEP150": silica particles, manufactured by Nippon Shokubai Co., Ltd.)

2) Formation of a light-to-heat conversion layer on the surface of a support The above-mentioned coating solution for a light-to-heat conversion layer was coated on one surface of a polyethylene terephthalate film (support) having a thickness of 75 μm using a wire bar. 120 ° C
After drying in an oven for 2 minutes, a light-to-heat conversion layer was formed on the support. The optical density of the obtained light-to-heat conversion layer at a wavelength of 808 nm was measured with a UV-spectrophotometer UV-240 manufactured by Shimadzu Corporation and found to be OD _LH = 1.03. Observation of the cross section of the light-to-heat conversion layer with a scanning electron microscope showed that the layer thickness T _LH was 0.3 μm on average.
Therefore, OD _LH / T _LH was 3.43.

3) Preparation of Coating Solution for Black Image Forming Layer The following components were placed in a kneader mill, and a pre-dispersion treatment was performed by applying a shearing force while adding a small amount of a solvent. A solvent was further added to the dispersion, and the dispersion was finally adjusted to have the following composition, followed by sand mill dispersion for 2 hours to obtain a pigment dispersion mother liquor. [Black pigment dispersion mother liquor composition] Composition 1-12.6 parts of polyvinyl butyral ("ESLEC B BL-SH", manufactured by Sekisui Chemical Co., Ltd.)-Pigment Black (pigment black) 7 (carbon black CI No. 77266) 4.5 parts ("Mitsubishi Carbon Black # 5", manufactured by Mitsubishi Chemical Corporation, PVC blackness: 1) ・ Dispersing aid 0.8 parts ("Solsperse S-20000", manufactured by ICI Corporation) -79.4 parts of n-propyl alcohol, composition 2-12.6 parts of polyvinyl butyral ("ESLEC B BL-SH", manufactured by Sekisui Chemical Co., Ltd.)-Pigment Black 7 (carbon black CI. No. 77266) 10.5 parts ("Mitsubishi Carbon Black MA100", manufactured by Mitsubishi Chemical Corporation, PVC black) : 1 0) Dispersion aid 0.8 parts ( "SOLSPERSE S-20000", ICI (Ltd.)) - n-propyl alcohol 79.4 parts

Next, the following components were mixed while stirring with a stirrer to prepare a coating solution for a black image forming layer. [Coating liquid composition for black image forming layer] 185.7 parts of the above-mentioned black pigment-dispersed mother liquor Composition 1: Composition 2 = 70:30 (parts) Polyvinyl butyral 11.9 parts ("ESLEC B BL-SH", Sekisui Chemical・ Wax-based compound (Stearic acid amide “Neutron 2”, manufactured by Nippon Seika Co., Ltd.) 1.7 parts (Behenic acid amide “Diamid BM”, manufactured by Nippon Kasei Co., Ltd.) 1 1.7 parts (Laurilic acid amide “Diamid Y”, manufactured by Nippon Kasei Co., Ltd.) 1.7 parts (Palmitic acid amide “Diamid KP”, manufactured by Nippon Kasei Co., Ltd.) 1.7 parts (Ercamidamide) 1.7 parts (Diamid L-200, manufactured by Nippon Kasei Co., Ltd.) 1.7 parts (oleamide amide “Diamid O-200”, manufactured by Nippon Kasei Co., Ltd.) 1.7 parts ・ Rosin 11.4 parts (“KE -311 ", Arakawa (Component: resin acid 80-97%; resin acid component: abietic acid 30-40%, neoabietic acid 10-20%, dihydroabietic acid 14%, tetrahydroabietic acid 14%) Activator 2.1 parts ("MegaFac F-176PF", solid content 20%, manufactured by Dainippon Ink and Chemicals, Inc.) 7.1 parts of inorganic pigment ("MEK-ST", 30% methyl ethyl ketone solution, Nissan Chemical (・ N-propyl alcohol 1050 parts ・ Methyl ethyl ketone 295 parts The particles in the obtained coating solution for a black image forming layer were measured using a laser scattering type particle size distribution analyzer. .25 μm, and the ratio of particles of 1 μm or more was 0.5%.

4) Formation of Black Image Forming Layer on Surface of Light-to-Heat Conversion Layer The above-mentioned coating solution for black image forming layer was applied to the surface of the light-to-heat conversion layer for 1 minute using a wire bar, and then the coated material was heated to 100 ° C. After drying in an oven for 2 minutes, a black image forming layer was formed on the light-to-heat conversion layer. Through the above steps, a heat transfer sheet (hereinafter, referred to as a heat transfer sheet K) in which a light-to-heat conversion layer and a black image forming layer are provided on the support in this order. Similarly, a yellow image forming layer and an image forming layer are also provided. The heat transfer sheet Y, the sheet provided with the magenta image forming layer is referred to as a heat transfer sheet M, and the sheet provided with the cyan image forming layer is referred to as a thermal transfer sheet C). The optical density (optical density: OD _I ) of the black image forming layer of the thermal transfer sheet K was measured using a Macbeth densitometer “TD-90”.
4 "(W filter), OD _I = 0.
91. When the thickness T _I of the black image forming layer was measured, it was 0.60 μm on average. Therefore, OD _I / T _I was 1.52.

The physical properties of the resulting image forming layer were as follows. The contact angle of the surface with water was 95 °. The surface hardness of the image forming layer was preferably 10 g or more, specifically 200 g or more, with a sapphire needle. The surface smoother value is 0.5-50 mmHg at 23 ° C and 55% RH.
(≒ 0.0665 to 6.65 kPa), specifically, 9.3 mmHg (≒ 1.24 kPa).
The coefficient of static friction of the surface is preferably 0.2 or less, specifically 0.08.

-Preparation of Thermal Transfer Sheet Y- The preparation of the thermal transfer sheet K was the same as the preparation of the thermal transfer sheet K except that the coating liquid for the yellow image forming layer having the following composition was used instead of the coating liquid for the black image forming layer. In the same manner as in the above, a thermal transfer sheet Y was produced. The thickness of the image forming layer of the obtained thermal transfer sheet Y was 0.42 μm on average. The measured optical density OD _I of the image forming layer of the thermal transfer sheet Y, was 1.10. Therefore, OD _I /
T _I was 2.62. [Yellow pigment dispersion mother liquor composition] Yellow pigment composition 1: 7.1 parts of polyvinyl butyral ("S-lec B BL-SH", manufactured by Sekisui Chemical Co., Ltd.) Pigment Yellow 180 (C.I.N.) 12.9 parts (“Novoperm Yellow (Novo Palm Yellow) P-HG”, manufactured by Clariant Japan K.K.) ・ 0.6 parts of dispersing aid (“Solsperse S-20000”, ICI Corporation)・ N-propyl alcohol 79.4 parts [Yellow pigment dispersion mother liquor composition] Yellow pigment composition 2: ・ Polyvinyl butyral 7.1 parts (“ESLEC B BL-SH”, manufactured by Sekisui Chemical Co., Ltd.) ・ Pigment Yellow (Pigment Yellow) 139 (CINO 56298) 12.9 parts ("Novoperm Yellow (Novo Palm Yellow) M2R 70", Clariant Japan K.K.)-0.6 parts of dispersing aid ("Solsperse S-20000", ICI K.K.)-n-propyl alcohol 79.4 Department

[Composition of Yellow Image Forming Layer Coating Solution] 126 parts of the above-mentioned yellow pigment dispersion mother liquor Yellow pigment composition 1: yellow pigment composition 2 = 95: 5 (part) 4.6 parts of polyvinyl butyral (“ESLEC B BL-1 SH, manufactured by Sekisui Chemical Co., Ltd.)-Wax compound (stearic amide "Neutron 2", manufactured by Nippon Seika Co., Ltd.) 0.7 parts (behenic amide "Diamid BM", Nippon Kasei (Manufactured by Nippon Kasei Co., Ltd.) 0.7 parts (lauric amide “Diamid Y” manufactured by Nippon Kasei Co., Ltd.) 0.7 parts (palmitic acid amide “Diamit KP” manufactured by Nippon Kasei Co., Ltd.) 0.7 Part (Ercamidamide "Diamid L-200", manufactured by Nippon Kasei Co., Ltd.) 0.7 part (Oleic acid amide "Diamid O-200", manufactured by Nippon Kasei Co., Ltd.) 0.7 part Nonionic World Activator 0.4 part ("Chemistat 1100", manufactured by Sanyo Chemical Co., Ltd.) 2.4 parts of rosin ("KE-311", manufactured by Arakawa Chemical Co., Ltd.) (Ingredient: resin acid 80-97%; resin) Acid component: abietic acid 30 to 40%, neo abietic acid 10 to 20%, dihydroabietic acid 14%, tetrahydroabietic acid 14%)-Surfactant 0.8 part ("MegaFac F-176PF", solid content) 20%, manufactured by Dainippon Ink and Chemicals, Inc.)-793 parts of n-propyl alcohol-198 parts of methyl ethyl ketone

The physical properties of the obtained image forming layer were as follows. The contact angle of the surface with water was 108 °.
The surface hardness of the image forming layer was preferably 10 g or more, specifically 200 g or more, with a sapphire needle. Surface smoother value is 0.5-50mmH at 23 ° C and 55% RH
g ($ 0.0665-6.65 kPa) was preferable, and specifically, it was 2.3 mmHg ($ 0.31 kPa). The coefficient of static friction of the surface is preferably 0.2 or less, specifically 0.1.

-Preparation of Thermal Transfer Sheet M- The preparation of the thermal transfer sheet K was the same as the preparation of the thermal transfer sheet K except that the coating solution for the magenta image forming layer having the following composition was used instead of the coating solution for the black image forming layer. In the same manner as in the above, a thermal transfer sheet M was produced. The thickness of the image forming layer of the obtained thermal transfer sheet M was 0.38 μm on average. The measured optical density OD _I of the image forming layer of the thermal transfer sheet M was 1.45. Therefore, OD _I /
T _I was 3.82. [Magenta pigment dispersion mother liquor composition] Magenta pigment composition 1; 12.6 parts of polyvinyl butyral ("Denka butyral # 2000-L", manufactured by Denki Kagaku Kogyo Co., Ltd., Vicat softening point 57C)-Pigment Red (Pigment Red) 57: 1 (CI No. 1 5850: 1) 15.0 parts ("Simuller Brilliant Carmine 6B-229", manufactured by Dainippon Ink and Chemicals, Inc.) 6 parts ("Solsperse S-20000", manufactured by ICI Co., Ltd.) n-propyl alcohol 80.4 parts [magenta pigment dispersed mother liquor composition] magenta pigment composition 2; polyvinyl butyral 12.6 parts -L ", manufactured by Denki Kagaku Kogyo KK, Vicat softening point 57 ℃) Pigment Red 57: 1 (CI No. 1 5850: 1) 15.0 parts ("Lionol Red 6B-4290G", manufactured by Toyo Ink Manufacturing Co., Ltd.) Auxiliary agent 0.6 part (“Solsperse S-20000”, manufactured by ICI Corporation) n-propyl alcohol 79.4 parts

[Coating liquid composition for magenta image forming layer] 163 parts of the above magenta pigment dispersed mother liquor Magenta pigment composition 1: magenta pigment composition 2 = 95: 5 (parts) Polyvinyl butyral 4.0 parts -L ", manufactured by Denki Kagaku Kogyo Co., Ltd., Vicat softening point 57 ° C)-Wax compound (stearic amide" Neutron 2 ", manufactured by Nippon Seika Co., Ltd.) 1.0 part (behenamide" Diamond " Mid BM, manufactured by Nippon Kasei Co., Ltd.) 1.0 part (lauric amide “Diamid Y”, manufactured by Nippon Kasei Co., Ltd.) 1.0 part (palmitic acid amide “Diamid KP”, Nippon Kasei Co., Ltd.) 1.0 part (erucamide "Diamind L-200", manufactured by Nippon Kasei Co., Ltd.) 1.0 part (oleic acid amide "Diamid O-200", Nippon Kasei Co., Ltd.) )) 1.0 part Nonionic surfactant 0.7 part ("Chemistat 1100", manufactured by Sanyo Chemical Co., Ltd.) 4.6 parts of rosin ("KE-311", manufactured by Arakawa Chemical Co., Ltd.) (Ingredient: resin acid 80 to 97%; resin acid component abietic acid 30 to 40%, neoabietic acid 10 to 20% dihydroabietic acid 14%, tetrahydroabietic acid 14%)-pentaerythritol tetraacrylate 2.5 parts (" NK ester A-TMMT ", manufactured by Shin-Nakamura Chemical Co., Ltd.-1.3 parts of surfactant (" Megafac F-176PF ", solid content 20%, manufactured by Dainippon Ink and Chemicals, Inc.)-n-propyl alcohol 848 parts ・ Methyl ethyl ketone 246 parts

The physical properties of the obtained image forming layer were as follows. The contact angle of the surface with water was 99 °. The surface hardness of the image forming layer was preferably 10 g or more, specifically 200 g or more, with a sapphire needle. The surface smoother value is 0.5-50 mmHg at 23 ° C and 55% RH.
(≒ 0.0665 to 6.65 kPa), specifically, 3.5 mmHg (≒ 0.47 kPa).
The coefficient of static friction of the surface is preferably 0.2 or less, specifically 0.08.

—Preparation of Thermal Transfer Sheet C— Preparation of thermal transfer sheet K, except that a coating solution for a cyan image forming layer having the following composition was used in place of the coating solution for a black image forming layer in the preparation of the thermal transfer sheet K In the same manner as in the above, a thermal transfer sheet C was produced. The thickness of the image forming layer of the obtained thermal transfer sheet C was 0.45 μm on average. The measured optical density OD _I of the image forming layer of the thermal transfer sheet C, was 1.59. Therefore, OD _I / T _I
Was 3.53. [Cyan Pigment Dispersion Mother Liquid Composition] Cyan Pigment Composition 1: 12.6 parts of polyvinyl butyral ("ESLEC B BL-SH", manufactured by Sekisui Chemical Co., Ltd.)-Pigment Blue 15: 4 (CI. No. 74160) 15.0 parts (“Cyanine Blue (Cyanine Blue) 700-10FG”, manufactured by Toyo Ink Mfg. Co., Ltd.) 0.8 parts of dispersing aid (“PW-36”, Kusumoto Kasei Co., Ltd. 110 parts of n-propyl alcohol [Cyan pigment dispersed mother liquor composition] Cyan pigment composition 2: 12.6 parts of polyvinyl butyral ("ESLEC B BL-SH", manufactured by Sekisui Chemical Co., Ltd.) Pigment Blue ( Pigment Blue) 15 (CI No. 74 160) 15.0 parts ("Lionol Blue" Chromatography) 7027 ", Toyo Ink Manufacturing Co., Ltd.) Dispersion aid 0.8 parts (" PW-36 ", manufactured by Kusumoto Kasei Co.), n-propyl alcohol 110 parts

[Composition of Cyan Image Forming Layer Coating Solution] 118 parts of the above-mentioned cyan pigment-dispersed mother liquor Cyan pigment composition 1: cyan pigment composition 2 = 90: 10 (part) 5.2 parts of polyvinyl butyral (“ESLEC B BL- SH, manufactured by Sekisui Chemical Co., Ltd.) 1.3 parts of inorganic pigment "MEK-ST" 1.0 parts of wax compound (stearic acid amide "Neutron 2" manufactured by Nippon Seika Co., Ltd.) Behenic acid amide "Diamid BM", manufactured by Nippon Kasei Co., Ltd. 1.0 part (Lauramide amide "Diamid Y", manufactured by Nippon Kasei Co., Ltd.) 1.0 part (palmitic acid amide "Diamind KP", Nippon Kasei Co., Ltd.) 1.0 part (Erucamide "Diamid L-200" (Nippon Kasei Co., Ltd.) 1.0 part (Oleic acid amide "Diamid O-200", Nippon Kasei Co., Ltd. )) 1.0 part ・ Rosin 2.8 parts (“KE-311”, manufactured by Arakawa Chemical Co., Ltd.) (Component: resin acid 80 to 97%; resin acid component: abietic acid 30 to 40%, neo abietin Acid 10 to 20%, dihydroabietic acid 14%, tetrahydroabietic acid 14%) 1.7 parts of pentaerythritol tetraacrylate ("NK ester A-TMMT", manufactured by Shin-Nakamura Chemical Co., Ltd.) Surfactant 1 0.7 parts (“MegaFac F-176PF”, solid content 20%, manufactured by Dainippon Ink and Chemicals, Inc.) ・ 890 parts of n-propyl alcohol ・ 247 parts of methyl ethyl ketone

The physical properties of the resulting image forming layer were as follows. The contact angle of the surface with water was 99 °. The surface hardness of the image forming layer was preferably 10 g or more, specifically 200 g or more, with a sapphire needle. The surface smoother value is 0.5-50 mmHg at 23 ° C and 55% RH.
(≒ 0.0665 to 6.65 kPa), specifically, 7.0 mmHg (≒ 0.93 kPa).
The coefficient of static friction of the surface is preferably 0.2 or less, specifically 0.08.

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

Using a small width coater, 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 material was wound up in a roll form, stored at room temperature for one week, and then used for image recording with the following laser beam. The physical properties of the obtained image receiving layer were as follows. The contact angle of the surface with water was 43 °. Surface roughness Ra is 0.4-0.01μ
m was preferable, and specifically 0.02 μm. The undulation on the surface of the image receiving layer was preferably 2 μm or less, specifically 1.2 μm. The smoother value of the surface of the image receiving layer is
0.5-50mmHg at 23 ℃, 55% RH (≒ 0.0665 ～ 6.65kPa)
And specifically, 0.8 mmHg (Ｈ0.11 k
Pa). The coefficient of static friction of the surface of the image receiving layer is preferably 0.8 or less, and specifically 0.37.

-Formation of Transfer Image- The image-receiving sheet (56 cm × 7 cm) prepared above was placed on a rotating drum having a diameter of 38 cm provided with a vacuum section hole having a diameter of 1 mm (one area density in an area of 3 cm × 8 cm).
9 cm) and vacuum-adsorbed. Then, 61c
The thermal transfer sheet K (black) cut into mx 84 cm is overlapped so as to protrude evenly from the image receiving sheet.
While squeezing with a squeeze roller, the sections were adhered and laminated so that air was sucked into the section holes. The degree of decompression when the section hole is closed is-
It was 150 mmHg (≒ 81.13 kPa). The drum is rotated, and a semiconductor laser beam having a wavelength of 808 nm is condensed from the outside onto the surface of the laminated body on the drum so as to form a 7 μm spot on the surface of the photothermal conversion layer. The laser image (image) was recorded on the laminate while moving in the direction perpendicular to the scanning direction) (sub-scanning). Laser irradiation conditions are as follows. The laser beam used in this embodiment was a multi-beam two-dimensional laser beam consisting of five parallel lines in the main scanning direction and three parallel lines in the sub-scanning direction. Laser power 110 mW Drum rotation speed 500 rpm Sub-scanning pitch 6.35 μm Ambient temperature and humidity 18 ° C 30%, 23 ° C 50%, 26 ° C
Three conditions of 65% The diameter of the exposure drum is preferably 360 mm or more, and specifically, the diameter was 380 mm. 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 sheets 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.

-Evaluation of Light Resistance (Hue Variation)-The above sample formed by irradiating a laser beam at 23 ° C. and 50% environment temperature and humidity using the thermal transfer sheet C and retransferred from the image receiving sheet to recording paper. In the image, the fluorescent light 10
The light was exposed under 00 Lux for 48 hours, the hue before and after the exposure was measured, and the color difference was calculated. Hue: X-rite, X-rit
L * a * b * values were measured by e938. Table 1 shows the results.

<Examples 2 to 4 and Comparative Example 1> In Example 1, the compounds shown in Table 1 were used in the coating liquid for the light-to-heat conversion layer in the amounts shown in Table 1 as the light-to-heat conversion substances, and the light-to-heat conversion was carried out. The same procedure as in Example 1 was carried out except that the thickness of the layer was adjusted so that the value of OD _LH / T _LH was described in Table 1, and the image forming layer of each thermal transfer sheet was obtained even under different environmental temperature and humidity. Is transferred to the image receiving sheet, and the four-color image transferred on the image receiving sheet is further transferred to recording paper to form a multi-color image. It was confirmed that a multicolor image having the transfer density obtained could be formed. The light resistance (fluctuation in hue) of the sample image retransferred from the image receiving sheet to the recording paper using the thermal transfer sheet C was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0178]

[Table 1]

In Table 1 above, NK-2014 is a cyanine dye having the following structure, manufactured by Nippon Kosaku Dyeing Co., Ltd.

[0180]

Embedded image

From the results shown in Table 1, it is clear that the images obtained by using the thermal transfer sheet of the present invention have excellent light fastness.

[0182]

According to the present invention, it is possible to provide a contract proof and an analog type color proof that can be used in the CTP era, which can replace the proof print and the analog type color proof. Color reproducibility consistent with color proof can be reproduced. Using the same pigment-based color material as the printing ink, it can be transferred to the actual paper,
A DDCP system without moiré can be provided. Further, according to the present invention, it is possible to transfer this paper, use the same pigment-based coloring material as the printing ink, and use a large size (A
2 / B2) A digital direct color proof system can be provided. The present invention employs a laser thin-film thermal transfer system, uses a pigment colorant, performs actual halftone dot recording, and transfers the actual paper. In addition, the present invention provides a multicolor image forming method capable of forming an image having a good transfer quality and a stable transfer density on an image receiving sheet even when laser recording is performed at a high energy with a laser beam having a multi-beam two-dimensional array. can do. In particular, in the present invention, since the light-to-heat conversion material of the specific structure represented by the general formula (1) is used for the light-to-heat conversion layer of the heat transfer sheet, the hue of the recorded image does not change, the light resistance is excellent, and the image quality deteriorates. And a multicolor image forming method using the thermal transfer sheet and irradiating a laser beam having the above-mentioned excellent properties.

[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 apparatus 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 5/26 HF term (Reference) 2C068 AA02 AA06 AA15 BB19 BC24 2H111 AA01 AA04 AA12 AA26 AA35 BA55 BA76 CA03 CA41

Claims (5)

[Claims] 1. An optical density (OD) on a support._LH) And layer thickness
(T_LHμm) and the ratio (OD_LH/ T_LH) Is greater than 0.57
An image forming layer having at least a light-to-heat conversion layer and an image forming layer;
The image forming layer and the image receiving layer of the image receiving sheet are superposed facing each other.
And irradiate the image forming layer with laser light
The area is transferred onto the image receiving layer of the image receiving sheet to record an image.
A heat transfer material used in the heat transfer sheet, wherein the light heat conversion material of the light heat conversion layer is represented by the following general formula (1).
Thermal transfer sheet characterized in that it is a compound to be formed. Embedded imageIn the formula: Z is a benzene ring, a naphthalene ring or a heteroaromatic
Represents an atomic group for forming an aromatic ring. T is O, S, S
e, N (R¹), C (R^Two) (R^Three) Or C (R^Four) = C
(R ^Five). Where R¹, R^TwoAnd R^ThreeAre independent
Represents an alkyl, alkenyl, or aryl group
You. R^FourAnd R^FiveAre each independently a hydrogen atom or a halogen atom
Child, alkyl group, aryl group, alkoxy group, aryl
Oxy group, carboxyl group, acyl group, acylamino
Group, carbamoyl group, sulfamoyl group or sulfone
Represents an amide group. L has 5 or 7 methine groups
A trivalent linking group formed by linking by a conjugated double bond
Represent. M represents a divalent linking group. X^-Replaces the anion
Represent. 2. The thermal transfer sheet according to claim 1, wherein the resolution of the recorded image is 2000 dpi or more. 3. The image forming layer according to claim 1, wherein the ratio (OD _I / T _I ) of the optical density (OD _I ) to the layer thickness (T _I μm) is 1.80 or more. 4. The thermal transfer sheet according to 1. 4. The thermal transfer sheet according to claim 1, wherein the thermal transfer sheet is used in combination with an image receiving sheet having a contact angle of water of the image receiving layer of 90 ° or less. 5. A thermal transfer sheet comprising: an image receiving sheet having an image receiving layer; and at least 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 a support. The image forming layer of the image receiving sheet and the image receiving layer of the image receiving sheet are superposed on each other and irradiated with laser light from the support side of the thermal transfer sheet, and the laser light irradiation area of the image forming layer is transferred onto the image receiving layer of the image receiving sheet. A multicolor image forming method comprising an image recording step, wherein each of the thermal transfer sheets is the thermal transfer sheet according to any one of claims 1 to 4.