JP2002274070A - Multi-color image forming method, and heat-transfer image receiving sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-color image forming method, which is an image forming method using abrasion, and wherein the carrying property and the accumulating property of image receiving sheets are improved, and an image of a high precision such as a color-proof or highly precise mask can be easily obtained based on the high processing stability. SOLUTION: For this multi-color image forming method, an image receiving sheet having an image receiving layer, and a heat-transfer sheet having a light-heat converting layer and an image forming layer on a supporting body are used. Then, the image forming layers of respective heat-transfer sheets and the image receiving layer of the image receiving sheet are confronted to each other and superposed, and a laser beam is cast. Then, the laser beam cast region of the image forming layer is transferred onto the image-receiving layer of the image-receiving sheet, and the image is recorded. The multi-color image forming method has such a process. In this case, the existing ratio of a nitrogen atom on the surface of the image receiving layer of the image receiving sheet is 0.5 mol% or higher. Also, for this heat-transfer image-receiving sheet, an image-receiving layer is provided on a supporting body. In this case, the existing ratio of a nitrogen atom on the surface of the image receiving layer is 0.5 mol% or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor image forming method for forming a high-resolution full-color image using a laser beam. In particular, the present invention relates to color proofing (D) in the printing field by laser recording from digital image signals.
The present invention relates to a multicolor image forming method useful for producing a direct digital color proof (DCP) or mask image. Further, when the present invention is applied to a multicolor image forming method, a high-definition image such as a color proof or a high-definition mask can be easily obtained based on excellent transportability and integration and high process stability. It also relates to a thermal transfer image receiving 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 strong demand for a dry method using no developer.

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

As a recording material used in a transfer image forming method using a laser beam, a photothermal conversion layer which absorbs a laser beam to generate heat, a wax having a pigment which is heat-meltable, a binder, etc. are provided on a support. Heat-melt transfer sheet having an image forming layer dispersed in the components
No. 58045) is known. In the image forming method using these recording materials, the heat generated in the laser light irradiation area of the light-to-heat conversion layer melts the image forming layer corresponding to the area, and is transferred onto the image receiving sheet laminated on the transfer sheet. Then, a transfer image is formed on the image receiving sheet.

Japanese Patent Application Laid-Open No. 6-219052 discloses that a light-to-heat conversion layer containing a light-to-heat conversion substance, a very thin (0.03-0.3 μm) heat-peeling layer, and a coloring material are provided on a support. There is disclosed a thermal transfer sheet provided with an image forming layer in this order. In this thermal transfer sheet, by being irradiated with laser light, the bonding force between the image forming layer and the light-to-heat conversion layer that are bonded by the interposition of the thermal release layer is reduced, and the thermal transfer sheet is laminated on the thermal transfer sheet. A high-definition image is formed on the image receiving sheet. The image forming method using the thermal transfer sheet utilizes so-called "ablation", and specifically, in a region irradiated with laser light, the heat release layer partially decomposes and evaporates. This utilizes a phenomenon in which the bonding force between the image forming layer and the light-to-heat conversion layer is weakened, and the image forming layer in that region is transferred to the image receiving sheet laminated thereon.

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

[0007]

In such an image forming method, high process stability is required as described above. For example, the image receiving sheet is required to have good transportability, and also to have good collectability because it is necessary to accumulate a plurality of recorded cut image receiving sheets. SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming method utilizing ablation, in which transportability and integration of an image receiving sheet are improved, and a high-definition image such as a color proof or a high-definition mask is formed based on high process stability. Is to provide a multicolor image forming method which can easily obtain a multicolor image. Another object of the present invention is that, when applied to a multicolor image forming method, a high-definition image such as a color proof or a high-definition mask can be easily formed based on excellent transportability and integration and high process stability. To provide a thermal transfer image-receiving sheet obtained by the method described above.

[0008]

According to the present invention, a multicolor image forming method and a thermal transfer image receiving sheet having the following constitutions are provided, and the above object of the present invention is achieved. 1. Using an image receiving sheet having an image receiving layer on a support and four types of thermal transfer sheets of yellow, magenta, cyan, and black having at least a light-to-heat conversion layer and an image forming layer on the support, Forming an image on the image receiving layer of the image receiving layer by irradiating a laser beam and irradiating a laser beam on the image forming layer and the image receiving layer of the image receiving sheet; A multicolor image forming method, wherein the content ratio of the nitrogen element on the surface of the image receiving layer is 0.5 mol% or more. 2. The content ratio of the nitrogen element on the surface of the image receiving layer is 1.6 m.
ol% or more, the multicolor image forming method as described in 1 above, wherein 3. 3. The multicolor image forming method according to the above item 1 or 2, wherein the content ratio of the nitrogen element on the back surface of the support provided with the image receiving layer is 0.5 mol% or more. 4. 3. The multicolor image forming method according to the above 1 or 2, wherein the proportion of the nitrogen element present on the back surface of the support provided with the image receiving layer is 1.1 mol% or more. 5. Wherein the nitrogen element on the surface of the image receiving layer of the image receiving sheet and the nitrogen element on the back surface of the support provided with the image receiving layer of the image receiving sheet are nitrogen elements contained in an antistatic agent. The multicolor image forming method according to any one of the above. 6. A thermal transfer image-receiving sheet, comprising: an image receiving layer provided on a support; and a nitrogen element present on a surface of the image receiving layer in an amount of 0.5 mol% or more. 7. The content ratio of the nitrogen element on the surface of the image receiving layer is 1.6 m.
The thermal transfer image-receiving sheet as described in 6 above, wherein the content is not less than ol%. 8. 8. The thermal transfer image-receiving sheet according to claim 6, wherein the proportion of the nitrogen element on the surface on the back side of the support on which the image receiving layer is provided is 0.7 mol% or more. 9. The nitrogen element present on the surface on the back side of the support on which the image receiving layer is provided is 1.1 mol% or more.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a multicolor image forming method according to the present invention, an image forming layer of a thermal transfer sheet and an image receiving layer of an image receiving sheet are superposed facing each other, and a laser beam is irradiated thereon. A step of transferring the irradiated area onto the image receiving layer of the image receiving sheet to record an image. The content ratio of the nitrogen element on the surface of the image receiving layer provided on the support of the image receiving sheet is 0.5 mol% or more, preferably 1.6 mol%.
That is all. Further, the support provided with the image receiving layer also has a nitrogen element abundance ratio of 0.7 mol on the back surface.
% Or more, more preferably 1.1 m
ol% or more. By the presence of the nitrogen element in the above range on the surface of the image receiving sheet, the electric resistance of the surface is reduced,
This prevents static electricity from being charged. As a result, the slip between the image receiving sheets is improved, the transportability of the image receiving sheet is improved, and the integration of the cut and recorded image receiving sheet is improved, so that a multicolor image can be formed with good process stability. it can.

In order for the nitrogen element to be present on the surface of the image receiving layer of the image receiving sheet in the above range, an appropriate amount of an antistatic agent containing the nitrogen element is added to a coating solution for forming the image receiving layer of the image receiving sheet. After the application, drying conditions may be appropriately set and drying may be performed. The added antistatic agent may bleed out to the surface of the image receiving layer to have a nitrogen element ratio in the above range.
The amount of the antistatic agent added and the drying conditions can be determined experimentally in advance. It depends on the type of components constituting the image receiving layer and the back coat layer, the type of antistatic agent, and the like. Generally, about 0.1 to 10% by mass is added to the image receiving layer.
A condition of drying at a temperature of 200C for 10 seconds to 20 minutes is adopted, but is not limited thereto. The nitrogen element is
It may be ionized. The measurement of the existence ratio of the nitrogen element on the surface is performed by ESCA (530 manufactured by Physical Electronics).
0 type).

In order to make the content ratio of the nitrogen element on the back surface on which the image receiving layer is provided within the above range, a nitrogen element-containing antistatic agent is added to the support of the image receiving sheet, and a coating solution is applied to the support. Before the heat treatment, the support may be heat-treated at a temperature of 40 ° C. or more and less than 70 ° C. for 2 to 7 days. Also,
By adding an antistatic agent only to the image receiving layer and winding the image receiving sheet into a roll, the antistatic agent bleed out to the surface of the image receiving layer is transferred to the back surface where the image receiving layer is present, and the image receiving sheet is also provided. Of the nitrogen element on the back surface on which the image receiving layer is provided can be in the above range. Further, the addition ratio of the nitrogen element can be set in the above range by adding a nitrogen-containing antistatic agent to the back coat layer.

The multicolor image forming method of the present invention will be described in more detail. The multicolor image forming method of the present invention can produce a high-definition image such as a color proof or a high-definition mask image with good process stability, and realizes a thermal transfer image by sharp halftone dots. In addition, the present invention is effective and suitable for a system capable of transferring paper and performing B2 size recording (515 mm × 728 mm; B2 size is 543 mm × 765 mm). This thermal transfer image is 2
A halftone image corresponding to the number of print lines can be obtained at a resolution of 400 to 2540 dpi. Each dot is blurred
Because there is almost no chipping and the shape is very sharp,
A high range of halftone dots from highlights to shadows 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, this thermal transfer image has a sharp halftone dot shape so that it can faithfully reproduce the halftone dot corresponding to the laser beam. -Stable reproducibility can be obtained with both concentrations.

This thermal transfer image is formed by using a coloring pigment used in printing ink, and has high repetition reproducibility, so that a highly accurate CMS (color management system) can be realized. In addition, this thermal transfer image can be made to substantially match the hue of Japan color, SWOP color and the like, that is, the hue of the printed matter, and the appearance of the color when the light source such as a fluorescent lamp or an incandescent lamp changes is the same as that of the printed matter. Can be shown. Further, since the thermal transfer image has a sharp dot shape, fine lines of fine characters can be clearly reproduced. The heat generated by the laser light
It 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 unheated portion. For this purpose, the thinning of the light-to-heat conversion layer in the thermal transfer sheet and the mechanical properties of the image forming layer are controlled.

By the way, in the simulation, it is estimated that the light-to-heat conversion layer instantaneously reaches about 700 ° C., and if the film is thin, deformation or destruction is likely to occur. When deformation or destruction occurs, the light-to-heat conversion layer is transferred to the image receiving sheet together with the transfer layer,
There is a real harm that the transferred image becomes non-uniform. On the other hand, in order to obtain a predetermined temperature, the photothermal conversion substance must be present in a high concentration in the film, which causes problems such as precipitation of a dye and migration to an adjacent layer. For this reason, it is preferable to reduce the thickness of the light-to-heat conversion layer to about 0.5 μm or less by selecting an infrared-absorbing dye having excellent light-to-heat conversion properties and a heat-resistant binder such as polyimide. Also, in general, when the light-to-heat conversion layer is deformed, or when the image forming layer itself is deformed by high heat, the image forming layer transferred to the image receiving layer causes thickness unevenness corresponding to the laser beam sub-scanning pattern, Therefore, the image becomes non-uniform, and the apparent transfer density decreases. This tendency is more remarkable as the thickness of the image forming layer is smaller. On the other hand, when the thickness of the image forming layer is large, the sharpness of the dots is impaired and the sensitivity is lowered. In order to balance these conflicting performances, it is preferable to improve transfer unevenness by adding a low melting point substance such as a wax to the image forming layer. Also, by appropriately increasing the film thickness by adding inorganic fine particles instead of the binder, the image forming layer is sharply broken at the interface between the heated portion and the non-heated portion,
Transfer unevenness can be improved while maintaining the sharpness and sensitivity of the dots. In general, a low-melting substance such as a wax tends to ooze or crystallize on the surface of the image forming layer, which may cause a problem in image quality or stability over time 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 in the image forming layer. Can be prevented from being separated. 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 a coating layer of a 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. As the polymer hydrophobization technique, a hydroxyl group is reacted with a hydrophobic group as described in JP-A-8-238858,
Crosslinking two or more hydroxyl groups with a hardener, and the like.

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

The image receiving sheet and the thermal transfer sheet are preferably held on a drum by vacuum contact. This vacuum contact is important because the image transfer behavior is very sensitive to the clearance between the image receiving layer surface of the image receiving sheet and the image forming layer surface of the transfer sheet since an image is formed by controlling the adhesive force between the two sheets. If the clearance between the materials is widened due to foreign matter such as dust, image defects and image transfer unevenness occur. In order to prevent such image defects and image transfer unevenness, it is preferable to form uniform unevenness on the thermal transfer sheet to improve the air flow and obtain a uniform clearance. As a method for forming irregularities on the thermal transfer sheet, there are generally post-treatments such as embossing and addition of a matting agent to the coating layer. However, addition of a matting agent is preferred for simplifying the manufacturing process and stabilizing the material with time. The matting agent needs to be larger than the thickness of the coating layer, and if the matting agent is added to the image forming layer, a problem occurs in that the image of the portion where the matting agent is present will be lost. It is preferable to add it to the conversion layer, whereby the image forming layer itself has a substantially uniform thickness, and a defect-free image can be obtained on the image receiving sheet.

In order to reliably reproduce the sharp dots as described above, a high-precision design is also required on the recording 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 on the drum.
The size of the thermal transfer sheet is made larger than that of the image receiving sheet because the thermal transfer sheet is further attracted from above the image receiving sheet. The air between the thermal transfer sheet and the image receiving sheet, which has the greatest effect on the recording performance, is sucked from the area of the thermal transfer sheet only outside the image receiving sheet.

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

The transport roller 7 at either the supply site or the transport site of the thermal transfer sheet roll and the image receiving sheet roll.
It is preferable to use an adhesive roll having an adhesive material disposed on the surface. By providing the adhesive roll, the surfaces of the thermal transfer sheet and the image receiving sheet can be cleaned. Examples of the adhesive material provided on the surface of the adhesive roll include ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, polyolefin resin, polybutadiene resin, styrene-butadiene copolymer (SB
R), styrene-ethylene-butene-styrene copolymer (SEBS), acrylonitrile-butadiene copolymer (NBR), polyisoprene resin (IR), styrene-
Examples include isoprene copolymer (SIS), acrylate copolymer, polyester resin, polyurethane resin, acrylic resin, butyl rubber, and polynorbornene.

The surface of the 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 should be 50 kg / mm ² (≒ 490 MPa) or less. Is preferred.

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

Hardness Hv = 1.854 P / d ² (kg / mm ² ) ≒ 1
8.1692 P / d ² (MPa) where P: magnitude of load (Kg), d: diagonal length of square of recess (mm)

In the present invention, the elastic material at 20 ° C. of the adhesive material used for the above-mentioned adhesive roll has an elastic modulus at 20 ° C.
It is preferable that the pressure be 200 kg / cm ² (≒ 19.6 MPa) or less, as in the above case, dusts as foreign substances can be sufficiently removed and image defects can be suppressed.

Surface roughness of the surface of the image forming layer of the thermal transfer sheet
The absolute value of the difference between Rz and the surface roughness Rz of the back layer surface is 3.0 or less, and the absolute value of the difference between the surface roughness Rz of the image receiving layer surface of the image receiving sheet and the surface roughness Rz of the back layer surface is 3.0. The following is preferred. 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 by JIS
Means the ten-point average surface roughness corresponding to the Rz (maximum height) of the mountain, from the highest surface to the fifth mountain height, using the average surface of the part extracted from the surface of the roughness by the reference area as the reference surface The distance between the average value of the valley floor and the average value of the depths of the valley bottoms from the deepest to the fifth is input and converted. For measurement, Tokyo Seimitsu Co., Ltd.
Use a 3D roughness meter (Surfcom 570A-3DF) made by Nissan.
The measurement direction is the vertical direction, the cutoff value is 0.08 mm, the measurement area is 0.6 mm × 0.4 mm, the feed pitch is 0.005 mm, and the measurement speed is 0.12 mm / s.

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

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

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

Next, an outline of a mechanism for forming a multicolor image by thin-film thermal transfer using a laser will be described with reference to FIG. 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 a laser beam 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.
The adhesive strength with the adhesive decreases (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 light used for light irradiation is preferably a multi-beam light, 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 light to be used can be used without particular limitation as long as it is a multi-beam, and is a gas laser light such as an argon ion laser light, a helium neon laser light, a helium cadmium laser light, or a solid laser light such as a YAG laser light. 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 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 0.5 to 0.5. It is preferably 0.7 μm. By doing so, it is possible to suppress a decrease in density due to uneven transfer when the black thermal transfer sheet is irradiated with laser. When the thickness of the image forming layer in the black thermal transfer sheet is less than 0.5 μm, when recording with high energy, the image density is greatly reduced due to transfer unevenness, and the image density required as a proof of printing is achieved. It can be difficult. This tendency becomes more remarkable under high-humidity conditions, and the concentration change due to the environment may be large. On the other hand, if the layer thickness exceeds 0.7 μm, the transfer sensitivity may decrease during laser recording, and the attachment of small dots may worsen, or the thin line may become thin. This tendency is more pronounced under low humidity conditions. Further, the resolution may be deteriorated. The layer thickness of the image forming layer in the black thermal transfer sheet is more preferably 0.55 to 0.65 μm, and particularly preferably 0.60 μm.

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

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

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

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

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

The thermal transfer recording using laser beam irradiation is capable of forming an image on an image receiving sheet by converting a laser beam into heat and transferring the image forming layer containing a pigment to an image receiving sheet using the thermal energy. 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. Thermal transfer recording using laser light irradiation includes, for example, conventionally known melt-type transfer, ablation-based transfer, and sublimation-type transfer. Above all, the above-mentioned thin film transfer type,
The ablation type is preferable in that an image having a hue similar to printing is created.

In addition, a thermal laminator is usually used to perform a process of transferring an image receiving sheet on which an image has been printed by a recording device to a printing paper (hereinafter referred to as “book paper”). 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 printed matter from a plate making system (for example, Celebra made by Fuji Photo Film Co., Ltd.), the system connection is as follows. Connect a CTP (Computer To Plate) system to the plate making system. By applying the printing plate thus output to a printing machine, a final printed matter is obtained. The recording device is connected to the plate making system as a color proof, and a PD system (registered trademark) is connected as proof drive software for bringing colors and halftone dots closer to the printed matter. Contone (continuous tone) data converted to raster data by the plate making system is converted to binary data for halftone dots and
It is output to the system and finally printed. On the other hand, the same contone data is also output to the PD system. PD
The 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. Important color data is
An image printed via the TP system and an image output from the recording device via the PD system are prepared, and their colorimetric values are compared to create a table so that the difference is minimized.

Hereinafter, the thermal transfer sheet and the image receiving sheet suitably used in the recording apparatus of the above system will be described.

[Thermal Transfer Sheet] The thermal transfer sheet has at least a light-to-heat conversion layer and an image forming layer on a support and, if necessary, other layers.

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

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

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

The thickness C of the first back layer is 0.01 to 1 μm.
m, more preferably 0.01 to 0.2 μm. Further, the film 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 thickness ratio C: D of the first and second back layers is preferably 1: 2 to 5: 1.

As the antistatic agent used in the first and second back layers, 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 can be used as an antistatic agent. As such conductive fine particles,
For example, ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , In ₂
O ₃ , MgO, BaO, CoO, CuO, Cu ₂ O, Ca
O, SrO, BaO ₂ , PbO, PbO ₂ , MnO ₃ , M
oO ₃ , SiO ₂ , ZrO ₂ , Ag ₂ O, Y ₂ O ₃ , Bi
₂ O ₃ , Ti ₂ O ₃ , Sb ₂ O ₃ , Sb ₂ O ₅ , K ₂ Ti
Oxides such as ₆ O ₁₃ , NaCaP ₂ O ₁₈ and MgB ₂ O ₅ ; Cu
Sulfides such as S and ZnS; SiC, TiC, ZrC, V
Carbides such as C, NbC, MoC, WC; Si ₃ N ₄ , Ti
Nitride such as N, ZrN, VN, NbN, Cr ₂ N; Ti
B ₂ , ZrB ₂ , NbB ₂ , TaB ₂ , CrB, MoB, W
Borides such as B and LaB ₅ ; TiSi ₂ , ZrSi ₂ , N
_{bSi 2, TaSi 2, CrSi 2} , MoSi 2, WSi 2
BaCO ₃ , CaCO ₃ , SrCO ₃ , Ba
Metal salts such as SO ₄ and CaSO ₄ ; SiN ₄ —SiC, 9A
Complexes such as l ₂ O ₃ -2B ₂ O ₃ may be mentioned, and these may be used alone or in combination of two or more. Of these,
SnO ₂ , ZnO, Al ₂ O ₃ , TiO ₂ , In ₂ O ₃ , Mg
O, BaO and MoO ₃ are preferable, and SnO ₂ , ZnO,
In ₂ O ₃ and TiO ₂ are more preferred, with SnO ₂ being particularly preferred.

When the image receiving sheet of the present invention is used in a laser thermal transfer recording system, the antistatic agent used in the back coat 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. 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 coat layers. The amount of the antistatic agent contained in the first backcoat layer is
10 to 1000 parts by mass with respect to 00 parts by mass is preferable,
200 to 800 parts by mass are more preferred. The amount of the antistatic agent contained in the second back coat layer is preferably from 0 to 300 parts by mass relative to 100 parts by mass of the binder,
-100 parts by mass is more preferred.

Examples of the binder used for forming the first and second back coat layers include homopolymers and copolymers of acrylic acid monomers such as acrylic acid, methacrylic acid, acrylic acid esters, and methacrylic acid esters. Coalesce, nitrocellulose, methylcellulose, ethylcellulose, cellulose acetate such as cellulose acetate, polyethylene, polypropylene, polystyrene, vinyl chloride copolymer, vinyl chloride-vinyl acetate copolymer, polyvinyl pyrrolidone, polyvinyl butyral, polyvinyl alcohol Vinyl polymers and copolymers of vinyl compounds, condensation polymers such as polyesters, polyurethanes and polyamides, butadiene-
Examples thereof include a rubber-based thermoplastic polymer such as a styrene copolymer, a polymer obtained by polymerizing and crosslinking a photopolymerizable or thermopolymerizable compound such as an epoxy compound, and a melamine compound.

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

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

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

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

[0059]

Embedded image

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

[0061]

Embedded image

[0062]

Embedded image

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

[0064]

Embedded image

[0065]

Embedded image

In the general formulas (V) to (VII), n and m are 1
Shows an integer of 0 to 100. In the formula (VI), the ratio of n: m is 6: 4 to 9: 1.

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

Examples of the matting material contained in the light-heat conversion layer include 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 mat material is usually 0.3 to 30 μm.
m, preferably 0.5 to 20 μm, and the addition amount is preferably 0.1 to 100 mg / m ² .

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

The light-to-heat conversion layer is prepared by dissolving a light-to-heat conversion substance and a binder, preparing a coating solution containing a matting material 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, it is preferable to dry at a temperature of 80 to 150 ° C.

If the amount of the binder in the light-to-heat conversion layer is too small, the cohesive force of the light-to-heat conversion layer is reduced, 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. The light-to-heat conversion layer has a wavelength of 808 nm and is 0.80 to 1.0.
Having an optical density of 26 is preferable because the transfer sensitivity of the image forming layer is improved.
More preferably, it has an optical density of 2 to 1.15.
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.

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

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

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

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

3) Cyan pigment Pigment Blue (Pigment Blue) 15
(C.I. No. 74160) Example) Lionol Blue 7
027 (manufactured by Toyo Ink Manufacturing Co., Ltd.), Fastogen
Blue (fastogen blue) BB (manufactured by Dainippon Ink and Chemicals, Inc.) Pigment Blue (pigment blue) 1
5: 1 (CI No. 74160) Example) Hosterperm Blue (Hoster Palm Blue) A2R (manufactured by Clariant Japan KK),
Fastogen Blue (fastogen blue)
5050 (manufactured by Dainippon Ink and Chemicals, Inc.) Pigment Blue 1
5: 2 (CI No. 74160) Example) Hosterperm Blue (Hoster Palm Blue) AFL (manufactured by Clariant Japan KK),
Irgalite Blue (Irgalite Blue)
BSP (Ciba Specialty Chemicals Co., Ltd.)
Pigment Blue (Pigment Blue) 1 Fastogen Blue (Fastgen Blue) GP (Dai Nippon Ink Chemical Industry Co., Ltd.)
5: 3 (CI No. 74160) Example) Hosterperm Blue (Hoster Palm Blue) B2G (manufactured by Clariant Japan K.K.),
Lionol Blue FG7330 (manufactured by Toyo Ink Mfg. Co., Ltd.), Cromo
phtal Blue (Chromophtal Blue) 4GN
P (made by Ciba Specialty Chemicals Co., Ltd.),
Fastogen Blue (fastogen 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.), Irg
alite Blue (Ilgarite Blue) GLN
F (made by Ciba Specialty Chemicals Co., Ltd.),
Fastogen Blue (fastogen blue)
FGS (manufactured by Dainippon Ink and Chemicals, Inc.) Pigment Blue 1
5: 6 (CI No. 74160) Example) Lionol Blue E
S (manufactured by Toyo Ink Mfg. Co., Ltd.) Pigment Blue 60
(C.I. No. 69800) Example) Hosterperm Blue (Hoster Palm Blue) RL01 (Clariant Japan K.K.)
Manufactured by Toyo Ink Mfg. Co., Ltd.), Lionogen Blue (Rionogen Blue) 6501 (manufactured by Toyo Ink Mfg. Co., Ltd.)

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

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

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

The image forming layer preferably contains 30 to 70% by mass of a pigment, more preferably 30 to 50% by mass. Further, the image forming layer is made of a resin of 70%.
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 other components. Waxes Examples of the waxes include mineral waxes, natural waxes, and synthetic waxes. Examples of the mineral wax include petroleum wax such as paraffin wax, microcrystalline wax, ester wax, and oxidized wax, montan wax, ozokerite, and ceresin. Above all, paraffin wax is preferred. The paraffin wax is separated from petroleum, and various types are commercially available depending on the melting point. Examples of the natural waxes include vegetable waxes such as carnauba wax, wood wax, ouriculi wax, and spal wax, and animal waxes such as beeswax, insect wax, shellac wax, and whale wax.

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

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

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

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

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

If the content of the additive in the image forming layer is too large, the resolution of the transferred image is reduced, the film strength of the image forming layer itself is reduced, and the adhesion between the photothermal conversion layer and the image forming layer is reduced. In some cases, 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 that absorbs the wavelength of the light source may be any of a pigment and a dye. It is preferable in terms of color reproduction to use a dye having a large absorption at the wavelength of the light source. Examples of near infrared dyes include:
The compounds described in JP-A-3-103476 can be exemplified.

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

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

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

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

On a support, a light-to-heat conversion layer, a heat-sensitive release layer,
In the case of a thermal transfer sheet having a configuration in which the image forming layers are laminated in this order, the heat-sensitive release layer decomposes and degrades by the heat transmitted from the light-to-heat conversion layer to generate gas. Then, due to the decomposition or the generation of gas, the heat-sensitive peeling layer partially disappears, or cohesive failure occurs in the heat-sensitive peeling layer, and the bonding force between the light-heat conversion layer and the image forming layer decreases. For this reason, depending on the behavior of the heat-sensitive release layer, a part of the heat-sensitive release layer may adhere to the image forming layer and appear on the surface of a finally formed image, which may cause color mixing of the image. Therefore, even when such transfer of the heat-sensitive release layer occurs, the heat-sensitive release layer is hardly colored, that is, high in visible light, so that no visual color mixture appears in the formed image. It is desirable to show permeability. Specifically, the light-absorbing rate of the heat-sensitive release layer is 50% or less, preferably 1 to visible light.
0% or less. In addition, instead of providing an independent heat-sensitive release layer on the thermal transfer sheet, the heat-sensitive material is added to a light-to-heat conversion layer coating solution to form a light-to-heat conversion layer. It can also be set as a structure. The coefficient of static friction of the outermost layer of the thermal transfer sheet on the side where the image forming layer is coated is 0.35 or less, preferably 0.20
It is preferable to do the following. The coefficient of static friction of the outermost layer is set to 0.
By setting the ratio to 35 or less, it is possible to eliminate the contamination of the roll 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 follows the method described in paragraph [0011] of Japanese Patent Application No. 2000-85759. The smoother value of the surface of the image forming layer is 0.5 to 5 at 23 ° C. and 55% RH.
0 mmHg (≒ 0.0665 to 6.6 kPa) is preferable, and Ra is preferably 0.05 to 0.4 μm. Micro gaps can be reduced, transfer,
Further, it is preferable in terms of image quality. (Japanese Patent Application No. 11-16740)
6). The Ra value is measured by a surface roughness measuring device (Surfco
m, manufactured by Tokyo Seiki Co., Ltd.)
Can be measured based on The surface hardness of the image forming layer is preferably less than 200 g with a sapphire needle.
After the thermal transfer sheet is charged according to US Federal Government Test Standard 4046, the charge potential of the image forming layer 1 second after the thermal transfer sheet is grounded is preferably -100 to 100V. The surface resistance of the image forming layer is 10 at 23 ° C. and 55% RH.
It is preferably ⁹ Ω or less.

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 and one layer thereon.
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 coat 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 is, for example, a thermoplastic resin, a mixed melt obtained by mixing an inorganic pigment or a filler made of an incompatible polymer or the like with the thermoplastic resin, a single layer or a multilayer by a melt extruder. It can be produced by forming a film and further stretching it uniaxially or biaxially. In this case, the porosity is determined by the selection of the resin and the filler, the mixing ratio, the stretching conditions, and the like.

As the thermoplastic resin, a polyolefin resin such as polypropylene and a polyethylene terephthalate resin are preferable because of their high crystallinity, excellent stretchability, and easy formation of voids. It is preferable to use the above-mentioned polyolefin resin or polyethylene terephthalate resin as a main component, and appropriately use a small amount of another thermoplastic resin in combination. As the inorganic pigment used as the filler, those having an average particle size of 1 to 20 μm are preferable, and calcium carbonate, clay, diatomaceous earth, titanium oxide, aluminum hydroxide, silica and the like can be used. When polyethylene terephthalate is used as the thermoplastic resin as the incompatible resin used as the filler, it is preferable to combine polypropylene or polymethylpentene as the filler. Small voids (voids)
The details of the support having the structure are described in Japanese Patent Application No. 11-290570. 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 corona 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 (hereinafter simply referred to as “image forming layer”) of the thermal transfer sheet. Surface treatment such as glow discharge treatment may be performed.

When the support is heat-treated so that the proportion of the nitrogen element on the surface opposite to the surface on which the image receiving layer of the image receiving sheet is provided is within the above range, the support contains the nitrogen element. Add antistatic agent. Examples of the antistatic agent to be used include an antistatic agent added to an image receiving layer described later. In this case, the support contains an antistatic agent in an amount of 0.
It is preferable to add 1 to 5% by mass.

(Image-Receiving Layer) In order to transfer the image-forming layer to the surface of the image-receiving sheet and fix it, it is preferable to provide one or more image-receiving layers on the support. The image receiving layer is preferably a layer formed mainly of an organic polymer binder. The binder is preferably a thermoplastic resin, for example, acrylic acid, methacrylic acid, acrylic acid ester, a homopolymer of acrylic monomers such as methacrylic acid ester and copolymers thereof, methyl cellulose, ethyl cellulose, Cellulose polymers such as cellulose acetate, homopolymers of vinyl monomers such as polystyrene, polyvinylpyrrolidone, polyvinyl butyral, polyvinyl alcohol, polyvinyl chloride and the like, and copolymers thereof, and condensation polymers such as polyesters and polyamides And a rubber-based polymer such as butadiene-styrene copolymer. The binder of the image receiving layer has a glass transition temperature (Tg) of 90 ° C. in order to obtain an appropriate adhesive strength between the image receiving layer and the image forming layer.
Preferably, it is a lower polymer. For this,
It is also possible to add a plasticizer to the image receiving layer. Further, the binder polymer preferably has a Tg of 30 ° C. or higher in order to prevent blocking between sheets. As the binder polymer of the image receiving layer, a polymer which is the same as or similar to the binder polymer of the image forming layer may be used in terms of improving adhesion with the image forming layer during laser recording and improving sensitivity and image strength. Particularly preferred. The smoother value of the image receiving layer surface is 23 ° C., 55% RH
0.5 to 50 mmHg ($ 0.0665 to 6.65 k
Pa) is preferable, and Ra is preferably 0.05 to 0.4 μm. This makes it possible to reduce a large number of micro voids in which the image receiving layer and the image forming layer cannot contact with each other on the contact surface. Furthermore, it is preferable in terms of image quality (Japanese Patent Application No.
-167406). The Ra value can be measured based on JIS B0601 using a surface roughness measuring instrument (Surfcom, manufactured by Tokyo Seiki Co., Ltd.) or the like. After the image receiving sheet is charged according to the US Federal Government Test Standard 4046, the charging potential of the image receiving layer 1 second after the image receiving sheet is grounded is preferably -100 to 100 V. It is preferable that the surface resistance of the image receiving layer is 10 ⁹ Ω or less at 23 ° C. and 55% RH. The coefficient of static friction on the surface of the image receiving layer is 0.
It is preferably 8 or less. The surface energy of the surface of the image receiving layer is preferably 23 to 35 mg / m ² .

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

Examples of the organic polymer (b) include the above-mentioned polymers for forming an image receiving layer. Further, as the photopolymerization initiator (c), a general photoradical polymerization initiator such as benzophenone, Michler's ketone, etc.
It is used at a ratio of 20% by mass.

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

An antistatic agent containing a nitrogen element is added to the image receiving layer so that the proportion of the nitrogen element on the surface of the image receiving layer falls within the above range. Examples of the antistatic agent used include nonionic surfactants such as polyoxyethylene alkylamine and polyoxyethylene alkylamide, cationic surfactants such as quaternary ammonium salts, and anionic surfactants such as ammonium polystyrene sulfonate. Activators, amphoteric surfactants such as alkyl betaine type, alkyl imidazoline type and alkyl alanine type, conductive resins such as polyvinyl benzyl type cation and polyacrylic acid type cation, and conductive fine particles are exemplified. Among them, a cationic surfactant such as a quaternary ammonium salt is preferably used. Antistatic agents can be used alone or in combination of two or more. It is preferable that an antistatic agent is added to the image receiving layer in an amount of 0.1 to 10% by mass.

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

The cushion layer is easily deformed when a stress is applied to the image receiving layer. To achieve the above-mentioned effect, a material having a low elastic modulus, a material having rubber elasticity, or 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 9.8 × 10 ^{5 to} 4.9 × 10 ⁷ Pa, particularly preferably 2.9 × 10 ^{6 to} 1.5 × 10 ⁷ Pa (Q: order confirmation required). ) Is preferred. In addition, in order to allow foreign substances such as dust to be immersed, the penetration (25 ° C., 100 g, 5 seconds) specified by JIS K2530 is preferably 10 or more. The glass transition temperature of the cushion layer is 80.
° C or lower, preferably 25 ° C or lower, and a softening point of 50 to 200.
C is preferred. It is also possible to suitably add a plasticizer to the binder in order to adjust these physical properties, for example, Tg.

Specific materials used as a binder for the cushion layer include rubbers such as urethane rubber, butadiene rubber, nitrile rubber, acrylic rubber, and natural rubber, as well as polyethylene, polypropylene, polyester, and styrene-butadiene copolymer. Copolymer, ethylene-vinyl acetate copolymer, ethylene-acryl copolymer, vinyl chloride-vinyl acetate copolymer, vinylidene chloride resin, vinyl chloride resin containing a plasticizer, polyamide resin, phenol resin and the like. The thickness of the cushion layer varies depending on the resin used and other conditions.
Preferably it is 10 to 52 μm.

The image receiving layer and the cushion layer need to be adhered to each other until the stage of laser recording. However, it is preferable that the image receiving layer and the cushion layer are releasably provided in order to transfer the image to the printing paper. In order to facilitate peeling, it is preferable to provide a peeling layer having a thickness of about 0.1 to 2 μm between the cushion layer and the image receiving layer. If the film 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 of the release layer is selected in accordance with the above physical properties, polycarbonate, acetal, and ethylcellulose are preferable in terms of preservability, and the use of an acrylic resin in the image receiving layer further improves the releasability when retransferring an image after laser thermal transfer. Particularly preferred.
Separately, a layer having extremely low adhesiveness to the image receiving layer upon cooling can be used as the release layer. In particular,
A layer mainly composed of a thermofusible 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. Another configuration of the release layer is a layer having a releasability by melting or softening upon heating to cause cohesive failure itself. Preferably, such a release layer contains a supercooled substance. Examples of the supercooled substance include poly-ε-caprolactone, polyoxyethylene, benzotriazole, tribenzylamine, and vanillin. Further, the peelable layer having another structure contains a compound that reduces the adhesiveness to the image receiving layer. Examples of such compounds include silicone resins such as silicone oil; fluorine resins such as Teflon (registered trademark) and fluorine-containing acrylic resins; polysiloxane resins; acetal resins such as polyvinyl butyral, polyvinyl acetal and polyvinyl formal; Solid waxes such as waxes and amide waxes; and fluorine-based and phosphate-based surfactants. Examples of the method of forming the release layer include coating the material obtained by dissolving the material in a solvent or dispersing it in a latex form with a blade coater, a roll coater, a bar coater, a curtain coater, a gravure coater, and the like, and an extrusion lamination method using a hot melt. It can be applied and can be applied and formed 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 described below may have a structure in which the image-receiving layer also serves as a cushion layer. / Cushioning image receiving layer may be used. Also in this case, it is preferable that the cushioning image-receiving layer is provided in a releasable manner so that the image can be retransferred to the printing paper. In this case, the image after retransfer to the printing paper becomes an image having excellent gloss. The thickness of the cushioning image receiving layer is 5 to 100 μm, preferably 10 to 100 μm.
４０40 μm.

It is preferable to provide a back coat layer on the surface of the support opposite to the surface on which the image receiving layer is provided, because 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 material such as silicon oxide and PMMA particles to the back coat layer in terms of improving the transportability in the recording apparatus. The additives can be added not only to the back coat layer but also to the image receiving layer and other layers as needed. The type of additive cannot be specified unconditionally depending on the purpose. For example, in the case of a mat material, particles having an average particle size of 0.5 to 10 μm can be added in the layer at about 0.5 to 80%. Various surfactants may be used as the antistatic agent so that the surface resistance of the layer is 10 ¹² Ω or less, more preferably 10 ⁹ Ω or less under the conditions of 23 ° C. and 50% RH.
It can be appropriately selected from the conductive agents and used.

The binder used for the back coat layer includes gelatin, polyvinyl alcohol, methyl cellulose, nitrocellulose, acetyl cellulose, aromatic polyamide resin, silicone resin, epoxy resin, alkyd resin, phenol resin, melamine resin, fluorine resin, polyimide resin. 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, fluoride General-purpose polymers such as polyurethane and polyethersulfone can be used. Crosslinking using a crosslinkable water-soluble binder as the binder of the backcoat layer is effective in preventing the mat material from falling off and improving the scratch resistance of the backcoat. 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 coat layer is provided, in order to impart adhesiveness to the support.

Organic or inorganic fine particles can be used as a mat material preferably added to the back coat layer. As an organic mat material, polymethyl methacrylate (P
MMA), fine particles of polystyrene, polyethylene, polypropylene, and other radical polymerization polymers, and fine particles of condensation polymers such as polyester and polycarbonate. The back coat layer is 0.5 to 5 g / m ^2.
It is preferable that the coating be provided in a certain amount. 0.5g / m
^If it is less than ² , the coating properties are unstable, and problems such as powder drop of the mat material are likely to occur. Also, if the coating is applied in excess of 5 g / m ² , the particle size of the suitable mat material becomes very large, and the image receiving layer surface is embossed by the back coat during storage, and in particular, thermal transfer for transferring a thin image forming layer. In this case, missing or unevenness of a recorded image is likely to occur. The mat material has a number average particle size that is larger than the film thickness of only the binder of the back coat layer by 2.
Those larger by 5 to 20 μm are preferred. Among the mat material, 8 [mu] m or more particles having a particle size of 5 mg / m ² or more is required, preferably 6~600mg / m ^2. This improves, in particular, foreign object failure. Further, by using a material having a narrow particle size distribution such that a value σ / rn (= coefficient of variation of the particle size distribution) obtained by dividing the standard deviation of the particle size distribution by the number average particle size is 0.3 or less, Defects caused by particles having an unusually large particle size can be improved, and desired performance can be obtained with a smaller amount of addition. This coefficient of variation is more preferably 0.15 or less.

The back coat layer is used to prevent the adhesion of foreign matter due to frictional electrification with the transport roll and jamming during transport, and to maintain good collectability of a plurality of recorded image receiving sheets on the discharge tray of the recording apparatus. It is preferable to add an antistatic agent. Examples of the antistatic agent include nonionic surfactants such as polyoxyethylene alkylamine and glycerin fatty acid ester, cationic surfactants such as quaternary ammonium salts, and anionic surfactants such as ammonium polystyrene sulfonate and alkyl phosphate. Agent,
In addition to amphoteric surfactants, conductive resins, and conductive fine particles, "1
1290 Chemical Products "Chemical Daily, 875-876
The compounds described on pages and the like are widely used. Among them, the use of a cationic surfactant containing a nitrogen element and an anionic surfactant such as ammonium polystyrene sulfonate is preferred. By performing the above-described heat treatment on the support provided with such a back coat layer as an antistatic agent, the dynamic friction force of the back coat layer of the image receiving sheet is reduced,
The transportability and stackability of the image receiving sheet are further improved. Antistatic agents can be used alone or in combination of two or more.

As the antistatic agent which can be used in combination with the back coat layer, conductive fine particles such as carbon oxide, metal oxides such as zinc oxide, titanium oxide and tin oxide, and organic semiconductors are preferably used among the above substances. In particular, the use of conductive fine particles is preferable because the antistatic agent does not dissociate from the back coat layer and a stable antistatic effect can be obtained regardless of the environment. Further, in order to impart coating properties and release properties to the back coat layer, it is also possible to add various activators, release agents such as silicone oil and fluorine-based resins. The back coat layer is particularly preferable when the softening points of the cushion layer and the image receiving layer 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-mentioned vacuum contact method is also suitably used. In the vacuum contact method, first, an image receiving sheet is wound on a drum provided with a suction hole for evacuation, and then a thermal transfer sheet slightly larger than the image receiving sheet is pressed while uniformly extruding air with a squeeze roller. This is a method in which the substrate is brought into close contact with a vacuum. As another method, there is a method in which an image-receiving sheet is mechanically attached to a metal drum while being pulled, and a thermal transfer sheet is similarly attached to the metal drum while being mechanically pulled and adhered. Among these methods, the vacuum adhesion method is particularly preferable because temperature control of a heat roller or the like is not required and lamination can be performed quickly and uniformly.

The multicolor image forming method of the present invention may be used
An image receiving sheet in which the content ratio of nitrogen element on the surface is in a specific range is itself new. Therefore, according to the present invention, the image receiving layer is formed on the support, and the content of the nitrogen element on the surface of the image receiving layer is 0.5 mol% or more, preferably 1.6 mol% or more.
The present invention provides a thermal transfer image-receiving sheet having a mol% or more. In a preferred embodiment of the thermal transfer image-receiving sheet, the proportion of the nitrogen element present on the surface on the back side of the support provided with the image-receiving layer is 0.7 mol% or more.
1 mol% or more. The method of producing such a thermal transfer image receiving sheet and its advantages have already been described.

[0120]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.
In addition, "part" means "part by mass" unless otherwise specified in the text.

Example 1-Preparation of Thermal Transfer Sheet K (Black)-[Formation of Back Layer] [Preparation of Back First Layer Coating Solution] Aqueous dispersion of acrylic resin 2 parts (Dulima ET410, solid content 20% by mass, Nippon Junyaku Co., Ltd.) Antistatic agent (water dispersion of tin oxide-antimony oxide) 7.0 parts (average particle size: 0.1 μm, 17% by mass) Polyoxyethylene phenyl ether 0.1 part Melamine compound 0.3 parts (Sumitic Resin M-3, manufactured by Sumitomo Chemical Co., Ltd.) Distilled water was prepared so that the total would be 100 parts [Formation of the first layer of the back] A biaxially stretched polyethylene terephthalate support of 75 μm thickness Body (Ra on both sides is 0.01μ)
m) is subjected to a corona treatment on one side (back side),
After applying the one-layer coating solution so that the dry film thickness becomes 0.03 μm
After drying at 180 ° C. for 30 seconds, the first bag layer was formed. The Young's modulus of the support in the longitudinal direction is 450 kg / mm ² (≒ 4.
4 GPa) and the Young's modulus in the width direction is 500 kg / mm ^2.
(≒ 4.9 GPa). F-5 in the longitudinal direction of the support
The value was 10 kg / mm ² (≒ 98 MPa), and the F-5 value in the support width direction was 13 kg / mm ² (≒ 127.4 MPa).
The heat shrinkage of the support at 100 ° C. for 30 minutes is 0.3% in the longitudinal direction and 0.1% in the width direction. The breaking strength is 20 kg / mm ² (≒ 196 MPa) in the longitudinal direction.
The width direction is 25 kg / mm ² (≒ 245 MPa), and the elastic modulus is 400 kg / mm ² (≒ 3.9 GPa). [Preparation of back layer second layer coating solution] Polyolefin 3.0 parts (Chemipearl S-120, 27% by mass, manufactured by Mitsui Petrochemical Co., Ltd.) Antistatic agent (tin oxide-antimony oxide aqueous dispersion) 2.0 Part (average particle size: 0.1 μm, 17% by mass) Colloidal silica 2.0 part (Snowtex C, 20% by mass, manufactured by Nissan Chemical Co., Ltd.) Epoxy compound 0.3 part (Dinacol EX-614B, Nagase (Formed by Kasei Co., Ltd.) Distilled water was prepared so that the total would be 100 parts. [Formation of the back second layer] The back second layer coating solution was applied on the back first layer so that the dry film thickness became 0.03 μm. After 170 ℃
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 coating solution for photothermal conversion layer]-7.6 parts of infrared absorbing dye ("NK-2014", a cyanine dye having the following structure, manufactured by Nippon Kogaku Dye Co., Ltd.)

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(Wherein, R represents CH ₃ and X ⁻ represents ClO ₄ ⁻ ) 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)

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(Wherein R ₁ represents SO _2. R ₂ represents

[0127]

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Is shown. Exonnaphtha 5.8 parts N-methylpyrrolidone (NMP) 1500 parts Methyl ethyl ketone 360 parts Surfactant 0.5 part ("MegaFac F-176PF", manufactured by Dainippon Ink and Chemicals, F-system interface) Activator) ・ Mat agent dispersion of the following composition 14.1 parts

[0129] Matting Agent Dispersion-N-methyl-2-pyrrolidone (NMP) 69 parts Methyl ethyl ketone 20 parts Styrene acrylic resin 3 parts ( "Joncryl 611", manufactured by Johnson Polymer (Ltd.)) · SiO ₂ particles 8 parts ("Sea Hostar KEP150": silica gel particles, manufactured by Nippon Shokubai Co., Ltd.)

2) Formation of a light-to-heat conversion layer on the surface of the support The above-mentioned coating solution for the 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 photothermal conversion layer at a wavelength of 808 nm was measured using a UV-spectrophotometer UV-24 manufactured by Shimadzu Corporation.
When measured at 0, the OD was 1.03. The layer thickness was 0.3 μm on average when the cross section of the photothermal conversion layer was observed with a scanning electron microscope.

3) Preparation of Coating Solution for Black Image Forming Layer The following components were placed in a kneader mill, and 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 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 (Erucamide) 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%) Agent 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 Co., Ltd.) 1050 parts of n-propyl alcohol. 295 parts of methyl ethyl ketone. The particles in the obtained coating solution for the black image forming layer were measured using a laser scattering type particle size distribution analyzer. 25 μm, and the ratio of particles having a size of 1 μm or more was 0.5%.

4) Formation of Black Image Forming Layer on the Surface of Light-to-Heat Conversion Layer The above-mentioned coating solution for the black image forming layer was applied to the surface of the light-to-heat conversion layer for 1 minute using a wire bar. 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) of the black image forming layer of the thermal transfer sheet K was measured using a Macbeth densitometer “TD-90”.
4 "(W filter), OD = 0.9
It was one. When the thickness of the black image forming layer was measured, it was 0.60 μm on average.

The physical properties of the obtained image forming layer were as follows. Surface hardness of image forming layer is 10 g with sapphire needle
The above was preferable, and specifically 200 g or more. Surface smoother value is 0.5-50mmHg at 23 ℃, 55% RH (≒
0.0665-6.65 kPa), specifically 9.3 m
mHg (≒ 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 a coating solution for a yellow image forming layer having the following composition was used instead of the coating solution for a black image forming layer. In the same manner as in the above, a thermal transfer sheet Y was produced. The layer thickness of the image forming layer of the obtained thermal transfer sheet Y was 0.42 μm. [Yellow pigment dispersion mother liquor composition] Yellow pigment composition 1: 7.1 parts of polyvinyl butyral ("ESLEK 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 (“ESREC B BL-SH”, manufactured by Sekisui Chemical Co., Ltd.) ・ Pigment Yellow (Pigment Yellow) 139 (CINO 56298) 12.9 parts ("Novoperm Yellow (Novopalm Yellow) M2R70", Clariant Japan K.K.)-0.6 parts of dispersing aid ("Solsperse S-20000", ICI K.K.)-n-propyl alcohol 79.4 Department

[Coating liquid composition for yellow image forming layer] 126 parts of the above-mentioned yellow pigment dispersion mother liquor Yellow pigment composition 1: yellow pigment composition 2 = 95: 5 (parts) 4.6 parts of polyvinyl butyral 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 part (lauric amide “Diamid Y”, manufactured by Nippon Kasei Co., Ltd.) 0.7 part (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.) (Ingredients: resin acid 80-97%; resin) Acid component: abietic acid 30-40%, neoabietic acid 10-20%, 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. Surface hardness of image forming layer is 10 g with sapphire needle
The above was preferable, and specifically 200 g or more. Surface smoother value is 0.5-50mmHg at 23 ℃, 55% RH (≒
0.0665 to 6.65 kPa), specifically, 2.3 m
mHg (≒ 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— Preparation of thermal transfer sheet K, except that a coating liquid for a magenta image forming layer having the following composition was used in place of the coating liquid for a black image forming layer in preparing the thermal transfer sheet K In the same manner as in the above, a thermal transfer sheet M was produced. The layer thickness of the image forming layer of the obtained thermal transfer sheet M was 0.38 μm. [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 (“Symler 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 dispersion mother liquor composition] magenta pigment composition 2;-polyvinyl butyral 12.6 parts ("denka butyral # 2000 -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 Composition for Magenta Image Forming Layer] 163 parts of the above-mentioned magenta pigment dispersion 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 amide "Diamid O-200", Nippon Kasei ( )) 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.) (Ingredients: resin acid 80-97%; resin acid component abietic acid 30-40%, neoabietic acid 10-20% 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. Surface hardness of image forming layer is 10 g with sapphire needle
The above was preferable, and specifically 200 g or more. Surface smoother value is 0.5-50mmHg at 23 ℃, 55% RH (≒
0.0665 to 6.65 kPa), specifically 3.5 m
mHg (≒ 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 the thermal transfer sheet K, except that a coating solution for a cyan image forming layer having the following composition was used instead of the coating solution for the 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 layer thickness of the image forming layer of the obtained thermal transfer sheet C was 0.45 μm. [Cyan pigment dispersed mother liquor 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 (C.I. 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 n-propyl alcohol [Cyan pigment dispersed mother liquor composition] Cyan pigment composition 2: 12.6 parts 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 (parts) 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-based compound (stearic acid amide "Neutron 2" manufactured by Nippon Seika Co., Ltd.) 1.0 part (lauric amide "Diamid Y", manufactured by Nippon Kasei Co., Ltd.) 1.0 part (palmitic acid amide "Diamind KP", manufactured by Nippon Kasei Co., Ltd.) 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%, neoavietin) Acids 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. 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 obtained image forming layer were as follows. Surface hardness of image forming layer is 10 g with sapphire needle
The above was preferable, and specifically 200 g or more. Surface smoother value is 0.5-50mmHg at 23 ℃, 55% RH (≒
0.0665 to 6.65 kPa) is preferable, and specifically, 7.0 m
mHg (≒ 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 (・ 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-propanol 50 copies

3) Coating solution for back coat layer The following acrylic polymer (A) and ammonium polystyrenesulfonate (B) were used at a mass ratio (A / B) of 80/20.
Was diluted to 4% by mass with water, and 0.3 parts by mass of colloidal silica having an average particle size of 0.12 μm was added to the solid content in the paint. This liquid was applied using a wire bar,
Dry for 2 minutes. Acrylic polymer (A): An acrylic polymer composed of 50 mol% of methyl methacrylate and 50 mol% of ethyl acrylate and having a carboxyl group and a methylol group introduced therein in an amount of 2.5 parts by mass and having an average molecular weight of 500,000.

Using a wire bar coating machine, a white PET
Support (“Lumirror # 130E58”, manufactured by Toray Industries, Inc.)
The above-mentioned coating solution for forming a cushion layer is applied on the above-mentioned coating layer, the coating layer is dried, and then the coating solution for the image receiving layer is applied and dried. The layer coating solution was applied and dried. The coating amount was adjusted so that the thickness of the cushion layer after drying was about 20 μm, the thickness of the image receiving layer was about 2 μm, and the thickness of the back coat layer was about 0.1 μm. The drying after the application of the image-receiving layer coating solution is performed by 1
The test was performed at 40 ° C. for 2 minutes. The white PET support is a void-containing polyethylene terephthalate layer (thickness: 116 μm).
m, porosity: 20%) and a titanium oxide-containing polyethylene terephthalate layer (thickness: 7 μm, titanium oxide content: 2%) provided on both surfaces thereof (total thickness: 130 μm)
m, specific gravity: 0.8). The produced material is wound up in roll form,
After storing at room temperature for one week, it was used for image recording by the following laser beam. The physical properties of the obtained image receiving layer were as follows. The surface roughness Ra was preferably from 0.4 to 0.01 μm, specifically 0.02 μm. 2μ of undulation on the surface of the image receiving layer
m or less, specifically 1.2 μm. The smoother value of the surface of the image receiving layer is 0.5 to 50 m at 23 ° C and 55% RH.
mHg (≒ 0.0665 to 6.65 kPa) was preferable, and specifically 0.8 mmHg (≒ 0.11 kPa). 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.times.7
9 cm) and vacuum-adsorbed. Then, 61c
The thermal transfer sheet K (black) cut to m × 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 spot of 7 μm on the surface of the photothermal conversion layer. The laser image (image) was recorded on the laminate while moving in the direction perpendicular to the scanning direction) (sub-scanning). Laser irradiation conditions are as follows. The laser beam used in this embodiment was a multi-beam two-dimensional laser beam consisting of five parallel lines in the main scanning direction and three parallel lines in the sub-scanning direction. Laser power 11mW Drum rotation speed 500rpm Sub-scanning pitch 6.35μm Ambient temperature and humidity 18 ° C 30%, 23 ° C 50%, 2
Three Conditions of 6 ° C. and 65% The diameter of the exposure drum is preferably 360 mm or more, and specifically, the one having 380 mm was used. The image size is 5
The size is 15 mm × 728 mm and the resolution is 2600 dpi. The laminated body after the laser recording was removed from the drum, and the thermal transfer sheet K was peeled off from the image receiving sheet by hand. It was confirmed that it was.

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

The proportion of the nitrogen element present on the surface of the image receiving layer, the kinetic frictional force on the surface of the image receiving layer, the kinetic frictional force on the surface of the back coat layer, and the integration were measured by the following methods. The results are shown in Table 1.・ Abundance ratio of nitrogen element: ESCA (Physical Electroni
cs 5300) under the following conditions. X-ray source: Anode: Mg Output: 400 W Voltage: 15 kV Photoelectron capture angle: 45 ° Capture condition: pass energy: 35.75 eV step: 0.05 eV, 50 ms F1s, C1s, O1s, S2p, N1s, Si2s,
The area of each peak was determined by narrow scan measurement of the Sn3d peak, and the element ratio was calculated from each RSF (sensitivity coefficient).・ Evaluation method of dynamic friction force (gf) between the image receiving surface and the back surface: the image receiving sheet is cut into strips of 7 × 16 cm (lower) and 5 × 15 cm (upper), and two image receiving surfaces are stacked downward and the lower sheet is stacked. Fixed to the table. One end of the upper sheet was set on a force gauge DFG-2K type manufactured by Simpo Corporation, placed under a load of 170 g (bottom surface φ4 cm), pulled at a speed of 1500 mm / min for 3 seconds, and displayed as a measured value “MIN” every second. The average maximum was read. (Measured five times and averaged.)-Integration: Luxel FINALPRO, manufactured by Fuji Photo Film Co., Ltd.
The thermal transfer image-receiving material in the form of a roll (558 mm in width, optional length) is set in an OF 5600 printer, and B2 vertical size (5
(58 × 841 mm), 20 sheets were continuously accumulated without recording an image, and the accumulation status was evaluated. As the shift amount, the maximum value of the shift at the upper end of the 20 sheets on the accumulation tray was measured. ◎: Good accumulation on the accumulation tray, maximum displacement 2 cm
Less than ○: Accumulated on the accumulation tray, less than 5 cm maximum displacement ×: Maximum displacement of 5 cm or more, or rounded
Jamming occurs and an accumulation error occurs.

Examples 2-3 and Comparative Examples 1-2 The procedure of Example 1 was repeated, except that the drying conditions after the application of the image-receiving layer coating solution were as shown in Table 1. . The results are shown in Tables 1 and 2.

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[Table 1]

[0153]

[Table 2]

The images formed on the image receiving sheet of the present invention were extremely good in all cases.

[0155]

According to the multicolor image forming method of the present invention, transportability and integration are improved, and a high-definition image such as a color proof or a high-definition mask image can be formed using an image receiving sheet with good process stability. Can be manufactured. Further, according to the method of the present invention, it is possible to provide a contract proof that replaces proofs and color art in response to the filmless in the CTP era, and this proof can be used with printed matter and color art for obtaining customer approval. Matched color reproducibility can be reproduced. It is possible to provide a DDCP system that uses the same pigment-based color material as the printing ink, can transfer to a real paper, and has no moire or the like. Further, according to the present invention, a large-size (A2 / B2) digital direct color printer capable of transferring to a real paper, using the same pigment-based coloring material as the printing ink, and having high similarity to a printed material.
System can be provided. The multicolor image forming method of the present invention is a method in which a real thin-film dot recording is performed by using a laser thin-film thermal transfer method, using a pigment coloring material, and transferring to a real paper. Even when laser recording is performed with high energy using a laser beam having a two-dimensional multi-beam array under different temperature and humidity conditions, an image with good image quality and a stable transfer density image can be formed on the image receiving sheet.

[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 schematic view showing a configuration example of a recording apparatus for laser thermal transfer.

[Explanation of symbols]

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

Claims (9)

[Claims] 1. An image receiving sheet having an image receiving layer on a support, and yellow, magenta, cyan, and black having at least a light-to-heat conversion layer and an image forming layer on the support.
Using a different type of thermal transfer sheet, the image forming layer of each thermal transfer sheet and the image receiving layer of the image receiving sheet are superposed facing each other, and irradiated with laser light, and the laser light irradiated area of the image forming layer is received by the image receiving sheet. A multicolor image forming method including a step of transferring an image onto a layer and recording an image, wherein a content ratio of a nitrogen element on the surface of the image receiving layer is 0.5 m
ol% or more. 2. The method according to claim 1, wherein the content ratio of the nitrogen element on the surface of the image receiving layer is 1.6 mol% or more.
2. The method for forming a multicolor image according to item 1. 3. The multicolor image forming method according to claim 1, wherein the content ratio of nitrogen element on the back surface of the support provided with the image receiving layer is 0.5 mol% or more. . 4. The multicolor image forming method according to claim 1, wherein the content ratio of the nitrogen element on the back surface of the support provided with the image receiving layer is 1.1 mol% or more. . 5. The method according to claim 1, wherein the nitrogen element on the surface of the image receiving layer of the image receiving sheet and the nitrogen element on the back surface of the support provided with the image receiving layer of the image receiving sheet are nitrogen elements of the antistatic agent. The multicolor image forming method according to claim 1. 6. An image receiving layer is provided on a support, and the content of a nitrogen element on the surface of the image receiving layer is 0.5 mol.
% Or more. 7. The method according to claim 6, wherein the content ratio of the nitrogen element on the surface of the image receiving layer is 1.6 mol% or more.
3. The thermal transfer image-receiving sheet according to item 1. 8. The nitrogen-existing ratio of 0.7 mol% on the surface on the back side of the support on which the image receiving layer is provided.
The thermal transfer image-receiving sheet according to claim 6, wherein: 9. The content ratio of a nitrogen element on the surface on the back side of the support on which the image receiving layer is provided is 1.1 mol%.
9. The thermal transfer image-receiving sheet according to claim 8, wherein: