JP2002356072A - Material and method for forming multicolor image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the adhesion between an image forming layer and an image receiving layer in laser transfer recording and to improve recording sensitivity, an image quality and transferability to final paper. SOLUTION: An image receiving sheet having the image receiving layer and four or more kinds of thermal transfer sheets being different in colors and each having a photothermal conversion layer and the image forming layer are used, and the image forming layer of each thermal transfer sheet and the image receiving layer of the image receiving sheet are laid opposite on each other. Irradiation with a laser light being conducted, a laser light irradiated area of the image forming layer is transferred onto the image receiving layer so that an image be recorded. In the present multicolor image forming material having the above constitution, the ratio ODr /film thickness between the reflecting optical density (ODr ) of the image forming layer of each thermal transfer sheet and the film thickness (μm) thereof is 1.50 or above and the recording area of a multicolor image of each thermal transfer sheet has a size of 515 mm×728 mm or more, while the resolution of a transfer image is 2400 dpi or above. At least one of monomer units constituting a binder is the same in the image forming layer and the image receiving layer and the smoothness of the surface of the image receiving layer is 0.5-50 mmHg, while the smoothness of the surface of the image forming layer is 2.2-50 mmHg.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a multicolor image forming material and a multicolor image forming method for forming a high-resolution full-color image using a laser beam. In particular, the present invention relates to a color proof (DDCP: Direct Digital
Or a multicolor image forming material and a multicolor image forming method useful for producing a mask image.

[0002]

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

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

As an image forming 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 heat-meltable pigment and a binder are provided on a support. A hot-melt transfer sheet having an image forming layer dispersed in such components in this order (JP-A-5-58045) is known. In the image forming method using these image forming 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 transfers it to 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.

As the DTP environment progresses, CTP (Computer To Platform)
e) There is no need for an intermediate film output process, and the need for proofing by the DDCP method has increased from proof printing and analog proofing. A large DDCP is desired. The laser thermal transfer system is capable of printing at a high resolution, and conventionally, there are systems such as a laser sublimation system, a laser ablation system, and a laser melting system. The laser sublimation method uses a dye as a coloring material, so the approximation of printed matter is not sufficient, and since the coloring material is sublimated, the outline of halftone dots is blurred and the resolution is not sufficiently high. there were. On the other hand, the laser ablation method uses a pigment as a coloring material, so the printed matter approximation is good.However, since the coloring material is scattered, the outline of a halftone dot is blurred similarly to the sublimation method, and the resolution is low. There was a problem that it was not high enough. Further, the laser melting method also has a problem that a clear contour does not appear because the melt flows.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and achieve the following objects. That is, an object of the present invention is to provide a large-sized DDCP having high quality, high stability, and excellent printing consistency. Specifically, the present invention provides: 1) a heat transfer sheet comprising a pigment coloring material, a printed material; The transfer of the color material thin film, which is not affected by the illumination light source even in comparison with
2) The image receiving sheet can stably and surely receive the image forming layer of the laser energy thermal transfer sheet. 3) Art (coated) paper, matte paper, finely coated paper, etc.
The paper can be transferred onto the paper in the range of 157 g / m ² , delicate texture rendering and accurate paper white (high-key portion) reproduction can be performed. 4) Further, extremely stable transfer releasability can be obtained. A multicolor image forming material that has good image quality and can form an image with a stable transfer density on an image receiving sheet even when laser recording is performed with high energy using a multi-beam laser beam under different temperature and humidity conditions. And a multicolor image forming method.

[0009]

Means according to the present invention for solving the above problems are as follows. (1) Thermal transfer using an image receiving sheet having an image receiving layer and thermal transfer sheets having at least four or more different colors including yellow, magenta, cyan, and black having at least a light-to-heat conversion layer and an image forming layer on a support. The image forming layer of the sheet and the image receiving layer of the image receiving sheet are superposed facing each other, irradiated with laser light, and the laser light irradiated area of the image forming layer is transferred onto the image receiving layer of the image receiving sheet to record an image. In the color image forming material, the ratio OD _r / film thickness of the reflection optical density (OD _r ) of the image forming layer of each of the thermal transfer sheets to the film thickness (in μm) is 1.50 or more. The recording area of the color image is 515 mm × 728 mm or more, and the resolution of the transferred image is 2400 d.
pi or more, and at least one monomer unit constituting the binder of the image forming layer and at least one monomer unit constituting the binder of the image receiving layer are the same, and the smoother value of the surface of the image receiving layer is 0. 0.5 to 50 mmHg, and the smoother value of the surface of the image forming layer is 2.2 to 50 mmHg. (2) The multicolor image forming material as described in (1) above, wherein the monomer unit of the binder is a vinyl acetal unit. (3) The multicolor image forming material as described in (1) above, wherein the monomer unit of the binder is a styrene unit. (4) The multicolor image forming material as described in (1) above, wherein the monomer unit of the binder is a butyral unit. (5) The above (1), wherein the monomer unit of the binder is a styrene acrylate unit.
The multicolor image forming material according to the above. (6) Thermal transfer using an image receiving sheet having an image receiving layer and thermal transfer sheets having at least four or more different colors including yellow, magenta, cyan, and black having at least a light-to-heat conversion layer and an image forming layer on a support. The image forming layer of the sheet and the image receiving layer of the image receiving sheet are superposed facing each other, irradiated with laser light, and the laser light irradiated area of the image forming layer is transferred onto the image receiving layer of the image receiving sheet to record an image. A multicolor image forming method, wherein the multicolor image forming material according to any one of the above (1) to (5) is used.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of intensive studies to provide a large-sized DDCP of B2 / A2 or more and B1 / A1 or more with high quality, high stability, and excellent print consistency, this paper transfer -Real dot output-Pigment type image forming material of B2 size or more, D consisting of output machine and high quality CMS software
Laser thermal transfer recording system for DCP was developed. Characteristics of the performance of the laser thermal transfer recording system we have developed,
The outline of the system configuration and technical points are as follows. The feature of the performance is that the dot shape is sharp,
It is possible to reproduce halftone dots with excellent printed matter approximation. Good hue print similarity. Since the recording quality is hardly affected by the environmental temperature and humidity, and the reproducibility is good, a stable proof can be created. The technical points of materials that can provide such performance characteristics are the establishment of thin film transfer technology, the improvement of vacuum adhesion retention of materials required for laser thermal transfer systems, the ability to follow high-resolution recording, and the improvement of heat resistance. It is. Specifically, thinning the light-to-heat conversion layer by introducing an infrared absorbing dye, enhancing the heat resistance of the light-to-heat conversion layer by introducing a high Tg polymer, stabilizing the hue by introducing a heat-resistant pigment, wax, Controlling the adhesive force and cohesive force by adding a low molecular component such as an inorganic pigment, and imparting vacuum adhesion without deteriorating the image quality by adding a matting material to the light-to-heat conversion layer are exemplified. The technical points of the system include air transport for continuous stacking of multiple recording devices, insertion of thermal transfer devices on the paper to reduce curl after transfer, connection of general-purpose output drivers with system connection expandability, etc. Can be Thus, the laser thermal transfer recording system we have developed is composed of various performance features, system configuration and technical points. However, these are examples, and the present invention is not limited to these means.

We believe that the individual materials, the light-to-heat conversion layer, the image forming layer, the image receiving layer, and other coating layers, as well as the thermal transfer sheets and image receiving sheets, do not exist individually but function organically and comprehensively. Further, the image forming material was developed based on the idea that the image forming material exhibited the best performance in combination with a recording device and a thermal transfer device. We thoroughly examine each coating layer of the image forming material and the constituent materials, make a coating layer that maximizes the characteristics of those materials, and use it as an image forming material. Appropriate range of physical properties of was found. As a result, the relationship between each material, each coating layer, each sheet and the physical properties was mastered, and further, by making the image forming material and the recording device or the thermal transfer device function organically and comprehensively, High-performance image forming materials could be found. The positioning of the present invention in such a system developed by us is an important invention that defines the relationship between the binder contained in the image forming layer and the image receiving layer and the smoother value of the surface of both layers.

The binder for the image-forming layer and the image-receiving layer used in the present invention includes various polymers described below, respectively. The monomer units constituting at least one binder are the same. By making the monomer units constituting the binder the same in the image forming layer and the image receiving layer, the adhesion between the image forming layer and the image receiving layer during laser transfer recording is improved, and the recording sensitivity, image quality, and paper transferability are improved. Can be done. In particular, vinyl acetal, styrene, butyral, styrene acrylate, and the like are preferable monomer units having excellent sensitivity and paper transferability. Among them, vinyl acetal, styrene, butyral, and styrene acrylate are particularly preferable. As the binder, a polymer obtained by polymerizing these monomer units alone or copolymerizing with other units is preferable. Examples of such a polymer include polyvinyl butyral-based and polystyrene-based resins, and vinyl chloride-vinyl acetate copolymer. Coalescence and the like.

Further, in the multicolor image forming material of the present invention, the smoother value of the surface of the image receiving layer is 0.5 to 50 mm.
Hg (≒ 0.0665 to 6.65 kPa), and the smoother value of the image forming layer surface is 2.2 to 50 mmHg.
(≒ 0.293 to 6.65 kPa). The smoother value in the present invention refers to the smoothness of the surface of the image receiving layer or the image forming layer, and is referred to as “Digital Smooster DSM-2”.
(Manufactured by Takenaka Systems), 23 ° C, 55% R
Refers to the value measured in H. By setting the smoother value of the surface of both layers to the above range, the image forming layer and the image receiving layer are combined with the same monomer unit constituting the binder, and the image forming layer at the time of laser transfer is used. And the image receiving layer, and the recording sensitivity and the image quality can be further improved. In this respect, the smoother value of the surface of the image receiving layer is more preferably 0.5 to 10 mmHg, and the smoother value of the surface of the image forming layer is 2.2 to 2.0 mmHg.
More preferably, it is 10 mmHg.

In the multicolor image forming material of the present invention, the ratio OD _r / layer thickness between the reflection optical density (OD _r ) and the layer thickness (in μm) of the image forming layer of each thermal transfer sheet is 1.50 or more. This OD _r / layer thickness is preferably 1.80 or more, more preferably 2.50 or more. There is no particular upper limit for OD _r / layer thickness, but at present, about 6 is the limit in consideration of the balance with other characteristics. OD _r / layer thickness is an index of the transfer density of the image forming layer and the transferred image. OD _r /
By setting the layer thickness in the above range, an image having high transfer density and good resolution can be obtained. Further, the color reproducibility can be improved by making the image forming layer thinner. OD _r is further obtained by actual paper transferred to Tokubishi art paper the image transferred to the image receiving sheet from the thermal transfer sheet, yellow at a concentration meter (X-rite938, X-rite Co.) (Y), magenta (M ), Cyan (C) or black (K). OD _r is preferably from 0.5 to 3.0,
0.8 to 2.0 is more preferable.

The multicolor image forming material of the present invention having the above characteristics has a transferred image resolution of 2400 dpi or more (more preferably 2600 dpi or more) and a recording area of 515 m.
mx 728 mm or more (more preferably 594 x 841 m
m or more).

Further, the characteristics that the multicolor image forming material of the present invention preferably has will be described. In the multicolor image forming material of the present invention, the OD _r / layer thickness is 1.50 or more as described above, and the contact angle of water between the image forming layer of each thermal transfer sheet and the image receiving layer of the image receiving sheet is set to 7.
It is preferable to set it in the range of 0 to 120.0 °. By setting the contact angle to water in the above range, a sufficient adhesive force can be obtained at the time of image formation, the dot shape can be sharpened, and excellent dot reproduction according to image information can be achieved. Further, even when transferred to the printing paper, it is possible to create a proof without defects without causing transfer failure. From the above point, the contact angle of water between the image forming layer and the image receiving layer is more preferably in the range of 30 to 100.0 °, and the contact angle of the image receiving layer to water is preferably 86 ° or less. More preferred. Further, the difference in contact angle of water between the image forming layer of the thermal transfer sheet and the image receiving layer of the image receiving sheet is 7%.
It is preferable to form the image forming layer and the image receiving layer so as to be within 3 °. When the difference in the contact angle between the two layers is within this range, the compatibility between the image forming layer and the image receiving layer becomes good, and the thermal adhesion is improved, so that the transfer sensitivity is improved. Since the smaller the difference in the contact angle, the better the compatibility, the difference in the contact angle between the image forming layer and the image receiving layer with water is within 73 °, preferably 65 °.
, More preferably within 50 °, particularly preferably 3 °
Within 0 °. In the present invention, the contact angle of the surface of each of the above-mentioned layers with water is determined by a contact angle meter (Contac).
t Angle Meter) A value measured using CA-A type (manufactured by Kyowa Interface Science Co., Ltd.).

In the present invention, it is preferred that at least one of the coating layers of the light-to-heat conversion layer, the image forming layer and the image receiving layer of the thermal transfer sheet contains a surface tension reducing agent. The surface tension lowering agent in the present invention is used in a coating solution such as a light-to-heat conversion layer, an image forming layer and an image receiving layer to reduce the surface tension of the coating solution and improve the wetting of the coating solution on the support. It has the function of eliminating coating defects such as repelling, dents, and the like, making each layer thinner and more uniform, and has the effect of increasing the recording area. As a typical example,
There are a fluorine-based surfactant, a silicon-based surfactant, a hydrocarbon-based surfactant and the like, and among them, a fluorine-based surfactant is preferable. In the present invention, of the molecular structure of the surfactant,
Surfactants substituted with F instead of H bonded to C of the lipophilic group are called fluorosurfactants. The fluorinated surfactant comprises a fluoroalkyl group, a solvophilic group, and a hydrophilic group, and those having a solvophilic group exhibit a surface tension lowering ability even for solvents other than water. The fluoroalkyl group preferably has 7 to 9 carbon atoms. As the above-mentioned solvent-philic group, an alkyl group or the like is preferable. As the hydrophilic group, a carboxyl group, a sulfonate group and the like are preferable.

Preferably, when the surface tension reducing agent is contained in a solvent of 1-propanol, methyl ethyl ketone, or N-methyl-2-pyrrolidone at a concentration of 0.5% by mass, the surface tension of each solvent is reduced. 2 for 1-propanol
2.5 mN / m or less and 2 for methyl ethyl ketone
It is better to be 2.5 mN / m or less and 25.0 mN / m or less for N-methyl-2-pyrrolidone. Specifically, it is preferably a perfluoroalkyl polyoxyalkylene oligomer.

Specific examples of the fluorinated surfactant include Megafac series (Megafac F177, F176, F113, F178) manufactured by Dainippon Ink and Chemicals, Inc.
K, F476, etc.), Surflon series (S111, S121, S131, etc.) manufactured by Asahi Glass Co., Ltd. and Florard series (FC93, FC135, FC43) manufactured by 3M Company.
0) and the like.

The amount of the surface tension reducing agent to be added to each layer can be appropriately selected depending on environmental conditions such as temperature and humidity, the conditions of the system to be applied, and the like. 0.000 based on the total amount of conversion layer coating solution
The amount is preferably from 0.01 to 2% by mass, more preferably from 0.00001 to 2% by mass based on the total amount of the coating solution for the image forming layer, and 0.00001 to the amount of the coating solution for the image receiving layer. ~ 2% by mass is preferred.

Further, in the present invention, it is preferable that at least two kinds of wax having a melting point of 100 ° C. or less are contained in any of the coating layers of the thermal transfer sheet and the image receiving sheet. The wax is defined as an organic substance having a solid or semi-solid alkyl group at room temperature (however, it melts in a temperature range from room temperature to about 150 ° C. and has a low melt viscosity). Various compounds described below can be used. The melting point of these waxes is preferably about 30C to 200C, more preferably 40C to 100C. The content of the wax in the image forming layer or the image receiving layer is preferably 0.5 to 50% by mass, and more preferably 5 to 30% by mass based on the total mass of the layer.
% By mass is more preferred. When it is contained in another layer, it is preferably 0.5 to 30% by mass, more preferably 1 to 15% by mass, based on the total mass of the layer. The effect of these waxes is that when heat is transmitted to the image forming layer and the image receiving layer, the wax is easily melted and the adhesion between the image forming layer and the image receiving layer can be increased. In addition, when it is contained in the image forming layer, it is possible to prevent the image forming layer from being broken at a high temperature, prevent image unevenness, and further improve the transfer sensitivity. On the other hand, when it is contained in the light-to-heat conversion layer, the resolving power with respect to the image forming layer can be controlled to increase the resolving power. In the present invention, as the two or more kinds of waxes, two or more kinds of fatty acid amides are preferably used. As the two or more kinds of fatty acid amides, a combination of a fatty acid amide of a fatty acid with a saturated fatty acid and a fatty acid amide of an unsaturated fatty acid is used. It is preferably used. The effect of including two or more types of wax is that the melting point can be lowered and the above effect can be exhibited more than in the case of using a single wax, and an image forming apparatus that prevents crystallization and is hardware Is prevented from being contaminated with wax crystals.

In the present invention, it is preferable that each coating layer contains acrylate and methacrylate. These include those that are liquid at room temperature. Specific examples include an acrylate compound described later in the section of the plasticizer. The content of each of the image forming layer and the image receiving layer in each coating layer is preferably 0.5 to 20 with respect to the total mass of the layer.
% By mass is preferable, and 1 to 10% by mass is more preferable. When contained in other layers, 0.5%
-20% by mass is preferred, and 1-10% by mass is more preferred.
The effects of these acrylates and methacrylates include:
It is possible to improve the elongation at break of the image forming layer to suppress image unevenness, and to improve the sensitivity because the Tg of the image forming layer is reduced and the image is transferred with less heat. In one embodiment of the present invention, each coating layer contains the monomer represented by the general formula (1) or a homo- or copolymer containing the monomer as a main component.

Further, in the present invention, the softening point measured by the ring and ball method is 100 ° C. or less, preferably 80 to 90 ° C. in the image forming layer of the thermal transfer sheet, and JIS
An acid number of from 2 to 220, preferably from 11 to 180, more preferably from 160 to 180, measured according to K3504
It is preferable that the rosin-based resin in the range described above is contained. The softening point according to the ring and ball method is JIS K2207,
It can be measured according to K7234.

Since the rosin-based resin functions as an excellent pressure-sensitive adhesive by incorporating the rosin-based resin having the above physical properties into the image-forming layer, the image formed on the image-forming layer of the thermal transfer sheet can be easily converted into an image-receiving sheet. Good transfer.
If the softening point of the rosin resin exceeds 100 ° C., the melting point of the image forming layer itself becomes high, causing a decrease in sensitivity, resulting in deterioration of the paper transferability and the above-mentioned effects are not exhibited. On the other hand, if the acid value is less than 11, the paper transferability is deteriorated, and the above effect is not exhibited.

Examples of the rosin-based resin include rosin, hydrogenated rosin, modified rosin and derivatives thereof (esterified products, etc.), and rosin-modified maleic resin. As the rosin acid constituting the rosin resin, either abietic acid type or pimaric acid type can be used. Above all, a resin containing at least 30% by mass of abietic acid-type rosin acid is preferable.
The rosin and the esterified product of the rosin and at least one polyhydric alcohol selected from ethylene glycol, glycerol and pentaerythritol are preferred. Specific examples of abietic acid type rosin acids include abietic acid, neoabietic acid, pasurutric acid,
Dihydro-abietic acid, dehydro-abietic acid and the like. The rosin resin is preferably contained in the image forming layer in an amount of 5 to 40% by mass, more preferably 10 to 20% by mass. The styrene / maleic acid copolymer resin may be used in combination with the rosin-based resin within the above-mentioned range.

In the image receiving layer of the image receiving sheet, the softening point measured by the ring and ball method is less than 130 ° C., preferably 80 to 90 ° C.
And a rosin resin having an acid value according to JIS K 3504 in the range of 2 to 250, preferably 10 to 250, more preferably 160 to 180. Since the rosin-based resin functions as an excellent pressure-sensitive adhesive by including the rosin-based resin having the above physical properties in the image receiving layer, the image formed on the image forming layer of the thermal transfer sheet can be transferred to the image receiving sheet with good resolution. . If the softening point of the rosin resin is 130 ° C. or higher, the melting point of the image forming layer itself becomes high, which causes a decrease in sensitivity, deteriorates the transferability of the paper, and does not exhibit the above effects. On the other hand, if the acid value is less than 10, the paper transferability deteriorates, and the above-mentioned effect is not exhibited.

Examples of the rosin-based resin contained in the image receiving layer include rosin, hydrogenated rosin, modified rosin and derivatives thereof (esterified products and the like), and rosin-modified maleic resin. As the rosin acid constituting the rosin resin, either abietic acid type or pimaric acid type can be used. Among them, rosin containing at least 30% by mass of abietic acid type rosin acid, and the rosin and ethylene glycol;
Esters with at least one polyhydric alcohol selected from glycerol and pentaerythritol are preferred. Specific examples of abietic acid-type rosin acids include abietic acid, neoabietic acid, pasurutric acid, dihydro-abietic acid, dehydro-abietic acid, tetrahydroabietic acid and the like. The rosin resin is preferably contained in the image receiving layer in an amount of 5 to 40% by mass, more preferably 1 to 40% by mass.
0-20 mass% is contained. The styrene / maleic acid copolymer resin may be used in combination with the rosin-based resin within the above-mentioned range.

When a rosin resin is used, it may be used for either one of the thermal transfer sheet and the image receiving sheet, or may be used for both.

Further, in the present invention, the ratio OD between the optical density (OD _LH ) of the light-to-heat conversion layer of the thermal transfer sheet and the layer thickness (μm unit) is used.
_LH / layer thickness is preferably 1.72 or more, and 2.06 or more.
It is more preferably at least 2.87, more preferably at least 2.87, particularly preferably at least 4.36. The upper limit of OD _LH / layer thickness is not particularly limited and is preferably as large as possible. However, at present, about 10 is the limit in consideration of balance with other characteristics. In the present invention, the OD _LH of the thermal transfer sheet refers to the absorbance of the photothermal conversion layer at the peak wavelength of the laser light used when recording the image forming material of the present invention, and can be measured using a known spectrophotometer. it can. In the present invention, a UV manufactured by Shimadzu Corporation
-A spectrophotometer UV-240 was used. In addition, the above OD _LH
Is the value obtained by subtracting the value of the support alone from the value including the support. OD _LH / layer thickness is related to thermal conductivity during recording,
It is an index that greatly affects the sensitivity and the temperature and humidity dependence of recording. By setting the OD _LH / layer thickness in the above range, the image density required for a print proof can be easily obtained, and at the same time, the image forming layer can be made thin, and the transfer to the image receiving layer can be efficiently performed. This makes it possible to increase the transfer sensitivity and sharpen the dot shape, thereby enabling excellent halftone dot reproduction in accordance with image information. In addition, since the light-to-heat conversion layer can be made thinner, the effects of environmental temperature and humidity can be minimized, so that the reproducibility of the image is improved,
A stable proof can be produced.

In the present invention, as described above, the recording area of the multicolor image on the thermal transfer sheet can be set to a size of 515 mm × 728 mm or more, preferably a size of 594 mm × 841 mm or more. The size of the image receiving sheet is preferably smaller by 0.5 cm or more on all sides than the thermal transfer sheet, and more preferably by 1 cm or more. In order to arrange the thermal transfer sheet on the drum having the suction holes on the image receiving sheet, and to adsorb the thermal transfer sheet onto the drum, it is preferable that the image receiving sheet has the above size.

Next, the entire system we have developed including the contents of the present invention will be described below. The system of the present invention achieves high resolution and high image quality by inventing and adopting the thin film thermal transfer method. In the system of the present invention, the resolution is 2400 dpi or more, preferably 2600 dpi.
This is a system that can obtain a transfer image of pi or more. The thin film thermal transfer system is a system in which a thin image forming layer having a layer thickness of 0.01 to 0.9 μ is transferred to an image receiving sheet in a state where it is not partially melted or hardly melted.
That is, since the recorded portion is transferred as a thin film, a thermal transfer system with extremely high resolution has been developed. A preferred method of efficiently performing thin-film thermal transfer is to deform the inside of the light-to-heat conversion layer into a dome shape by optical recording, push up the image forming layer, increase the adhesion between the image forming layer and the image receiving layer, and facilitate transfer. is there. If this deformation is large, the force of pressing the image forming layer against the image receiving layer is large, so it becomes easy to transfer,
On the other hand, if the deformation is small, the force for pressing the image forming layer against the image receiving layer is small, so that a portion where sufficient transfer cannot be performed appears.
Therefore, a preferable deformation for the thin film transfer is a laser microscope (VK
8500, manufactured by KEYENCE CORPORATION), and the magnitude of this deformation was determined by the increased cross-sectional area (a) of the recording portion of the photothermal conversion layer after optical recording and the cross-sectional area of the recording portion of the photothermal conversion layer before optical recording. The value obtained by dividing the value obtained by adding (b) by the cross-sectional area (b) of the recording portion of the light-to-heat conversion layer before optical recording can be evaluated by a deformation rate calculated by multiplying by 100. That is, the deformation ratio = ｛(a + b) /
(B) Δ × 100. The deformation rate is 110% or more, preferably 125% or more, and more preferably 150% or more. If the elongation at break is increased, the deformation ratio may be larger than 250%, but it is usually preferable to suppress the deformation ratio to about 250%.

The technical points of the image forming material in the thin film transfer are as follows. 1. Compatibility of high thermal response and preservation To achieve high image quality, it is necessary to transfer a submicron-order thin film, but in order to obtain the desired density, it is necessary to create a layer in which pigment is dispersed at a high density. , Contrary to thermal responsiveness. In addition, the thermal responsiveness is in a relationship opposite to the preservability (adhesion). These conflicting relations have been solved by the development of new polymers and additives. 2. Ensuring high vacuum adhesion In thin film transfer pursuing high resolution, it is preferable that the transfer interface is smooth, but sufficient vacuum adhesion cannot be obtained with that.
The standard gap between the thermal transfer sheet and the image receiving sheet is evenly distributed by adding a large amount of a matting agent with a relatively small particle size to the layer below the image forming layer, regardless of the conventional sense of providing vacuum adhesion. In this case, vacuum adhesion was imparted while maintaining the characteristics of the thin-film transfer without causing the image to be removed by the matting agent. 3. Use of heat-resistant organic material The photothermal conversion layer that converts laser light into heat at the time of laser recording is about 700 ° C, and the image forming layer containing a pigment coloring material is about 500 ° C.
℃. Along with developing a modified polyimide that can be coated with an organic solvent as a material for the light-to-heat conversion layer, it has higher heat resistance than printing pigments as a pigment coloring material, and has a safe and hue.
Pigments have been developed. 4. Ensuring surface cleanliness In thin film transfer, dust between the thermal transfer sheet and the image receiving sheet causes image defects, which is a serious problem. Entry from outside the device
Due to the occurrence of material cutting, etc., material management alone was not enough, and it was necessary to attach a mechanism to remove debris from the equipment. By changing the material of the transport roller, it was possible to remove dust without lowering the productivity.

Hereinafter, the entire system of the present invention will be described in detail. The present invention realizes a thermal transfer image with a sharp halftone dot, and performs a paper transfer and a recording (515 mm or more) of B2 size or more.
× 728 mm or more). More preferably, the B2 size is 543 mm x 765 mm,
This is a system that can record to a larger size.

One of the performance features of the system developed by the present invention is that a sharp dot shape can be obtained. The thermal transfer image obtained by this system can be a halftone image corresponding to the number of printing lines at a resolution of 2400 dpi or more. Since each halftone dot has very little bleeding or chipping and a very sharp shape, 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 CTP setter, and to reproduce halftone dots and gradation with good print similarity. The second feature of the performance of the system developed by the present invention is that the repeatability is good. This thermal transfer image has a sharp halftone dot shape, so that it can faithfully reproduce the halftone dot corresponding to the laser beam. In both cases, stable reproducibility can be obtained.

A third feature of the performance of the system developed by the present invention is that color reproduction is good. The thermal transfer image obtained by this system is formed using the coloring pigment used in the printing ink, and has high repetition reproducibility, so that a highly accurate CMS (color management system) can be realized. Also, this thermal transfer image can be made to substantially match the hue of Japan color, SWOP color, etc., that is, the hue of the printed matter, and the appearance of the color when the light source changes, such as a fluorescent lamp or incandescent lamp, is the same as that of the printed matter. Can be shown. A fourth performance feature of the system developed by the present invention is that the character quality is good. Since the thermal transfer image obtained by this system has a sharp dot shape, fine lines of fine characters can be clearly reproduced.

Next, the characteristics of the material technology of the system of the present invention will be described in more detail. As a thermal transfer method for DDCP, there is a sublimation method, an ablation method, and a heat melting method. In the method (1), the color material is sublimated or scattered, so that the outline of the halftone dot is blurred. In either method, the melt flows and no clear contour is produced. Based on thin-film transfer technology, we will clear new problems in the laser thermal transfer system and achieve higher image quality.
The technology described below has been incorporated. The first of the characteristics of material technology
Is the sharpening of the dot shape. Laser light is converted into heat by a light-to-heat conversion layer, transmitted to an adjacent image forming layer, and the image forming layer is adhered to the image receiving layer to perform image recording. In order to sharpen the dot shape, heat generated by the laser beam is transmitted to the transfer interface without diffusing in the plane direction, and the image forming layer is sharply broken at the interface between the heated part and the non-heated part. is necessary. 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.

Technique 1 for sharpening the dot shape is to make the light-to-heat conversion layer thinner. In the simulation, it is estimated that the light-to-heat conversion layer instantaneously reaches approximately 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 image forming layer,
There is a real harm that the transferred image becomes uneven. 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. Conventionally, carbon was often used as the light-to-heat conversion material. However, in the present material, an infrared absorbing dye that requires less use than carbon was used. As the binder, a polyimide compound having sufficient mechanical strength even at a high temperature and having good retention of an infrared absorbing dye was introduced. As described above, by selecting a heat-resistant binder such as an infrared-absorbing dye and a polyimide-based material having excellent light-to-heat conversion characteristics,
It is preferable to make the light-to-heat conversion layer thinner to about 0.5 μm or less.

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

In general, low-melting substances such as wax are
There is a tendency to seep or crystallize on the surface of the image forming layer,
In some cases, a problem may occur in the image quality or the temporal stability of the thermal transfer sheet. In order to cope with this problem, it is preferable to use a low melting point substance having a small difference in SP value from the polymer of the image forming layer, to increase the compatibility with the polymer and to separate the low melting point substance from the image forming layer. Can be prevented. It is also preferable to mix several kinds of low-melting substances having different structures so as to make them eutectic to prevent crystallization. As a result, an image having a sharp dot shape and less unevenness can be obtained.
The second characteristic of the material technology is that it has been found that the recording sensitivity has temperature and humidity dependence. Generally, when a coating layer of a thermal transfer sheet absorbs moisture, the physical 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. Japanese Patent Application Laid-Open No. Hei 8-23 discloses a technique for polymer hydrophobicity.
As described in JP-A No. 8858, a hydroxyl group is reacted with a hydrophobic group, and two or more hydroxyl groups are crosslinked with a hardener.

The third characteristic of the material technology is that the approximation of the printed matter of the hue is improved. In addition to the color matching of pigments in a thermal head type color proof (for example, FirstProof manufactured by Fuji Photo Film Co., Ltd.) and a stable dispersion technique, the following problems newly generated in a laser thermal transfer system have been cleared. That is, the technique 1 for improving the approximation of the printed matter of the hue is that a highly heat-resistant pigment is used. Normally, when printing by laser exposure, the image forming layer also receives heat of about 500 ° C or more, and some pigments used conventionally decompose thermally, but pigments with high heat resistance are used for the image forming layer By doing so, this can be prevented. The second technique for improving the closeness of the printed matter to the hue is prevention of diffusion of the infrared absorbing dye.
As described above, in order to prevent the hue from changing when the infrared absorbing dye moves from the light-to-heat conversion layer to the image forming layer due to high heat during printing, 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 by a combination of / binder.

The fourth characteristic of the material technology is to increase the sensitivity.
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. Furthermore, for the purpose of increasing the effect of the image forming layer flowing slightly during heating and filling the gap and the adhesiveness with the image receiving layer,
It is preferable to add a low melting point substance to the image forming 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 fifth feature of the material technology is improvement in vacuum adhesion. The image receiving sheet and the thermal transfer sheet are preferably held on a drum by vacuum contact. This vacuum adhesion is important because the image transfer behavior is very sensitive to the clearance between the image receiving layer surface of the image receiving sheet and the image forming layer surface of the transfer sheet since an image is formed by controlling the adhesive force between the two sheets. If the clearance between the materials is widened due to foreign matter such as dust, image defects and image transfer unevenness occur. In order to prevent such image defects and image transfer unevenness, it is preferable that uniform unevenness is provided on the thermal transfer sheet so that the air can be flowed well and uniform clearance can be obtained.

The first technique for improving the vacuum adhesion is to make the surface of the thermal transfer sheet uneven. Irregularities were formed on the thermal transfer sheet so that the effect of vacuum adhesion could be sufficiently exerted even when printing two or more colors. As a method of 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 over time. The matting agent needs to be larger than the thickness of the coating layer, and if the matting agent is added to the image forming layer, a problem occurs in that the image of the portion where the matting agent is present will be lost. It is preferable to add it to the conversion layer, whereby the image forming layer itself has a substantially uniform thickness, and a defect-free image can be obtained on the image receiving sheet.

Next, the features of the systematization technique of the system of the present invention will be described. Feature 1 of the systematization technology is the configuration of the recording device. In order to reliably reproduce the sharp dots as described above, a high-precision design is also required on the recording device side. The basic configuration is the same as that of the conventional laser thermal transfer recording apparatus. In this configuration, a recording head equipped with a plurality of high-power lasers irradiates a laser to a thermal transfer sheet and an image receiving sheet fixed on a drum, and performs recording.
This is a so-called heat mode outer drum recording system. Among them, the following embodiments are preferred configurations. The first configuration of the recording apparatus is to avoid mixing of dust. The supply of the image receiving sheet and the thermal transfer sheet is a fully automatic roll supply. Since a small number of sheets are supplied with a large amount of dust generated from the human body, roll supply was adopted. Since the thermal transfer sheet has one roll for each of the four colors, the loading unit rotates to switch the roll for each color.
Each film is cut into a predetermined length by a cutter during loading, and then fixed to a drum. The second configuration of the recording apparatus is to strengthen the adhesion between the image receiving sheet and the thermal transfer sheet on the recording drum. The image receiving sheet and the thermal transfer sheet are fixed to the recording drum by vacuum suction. Since the adhesive force between the image receiving sheet and the thermal transfer sheet cannot be increased by mechanical fixing, vacuum suction is employed. A number of vacuum suction holes are formed on the recording drum, and the inside of the drum is depressurized by a blower, a decompression pump, or the like, so that the sheet is adsorbed to the drum. The size of the thermal transfer sheet is made larger than that of the image receiving sheet because the thermal transfer sheet is further attracted from above the image receiving sheet. The air between the thermal transfer sheet and the image receiving sheet, which has the greatest effect on the recording performance, is sucked from the area of the thermal transfer sheet only outside the image receiving sheet.

Configuration 3 of the recording apparatus is to stably accumulate a plurality of sheets on a discharge table. In this apparatus, it is assumed that many sheets having a large area of B2 size or more can be stacked and stacked on the discharge table. Already integrated film A with thermal adhesion
When the next sheet B is discharged onto the image receiving layer, both may be stuck. If sticking, the next sheet will not be properly ejected and a jam will occur, which is a problem. It is best to prevent contact between the films A and B to prevent sticking. Several methods are known as contact prevention measures. (a) a method of creating a gap between the films by providing a step on the discharge table and making the film shape non-flat,
(b) A method in which the discharge port is positioned higher than the discharge table and the discharged film is dropped from above, (c) A method in which air is blown out between the two films to lift the film discharged later, etc. There is. In this system, since the sheet size is very large as B2, the structure of (a) and (b) becomes very large, so the air ejection method of (c) was adopted. 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 of forming a full-color image by applying the image forming material to the present apparatus as described above (hereinafter, referred to as an image forming sequence of the present system) will be described. 1) The sub-scanning axis of the recording head 2 of the recording apparatus 1 is returned to the origin by the sub-scanning rail 3, and the main scanning rotation axis of the recording drum 4 and the thermal transfer sheet loading unit 5 are returned to the origin. 2) The image receiving sheet roll 6 is unwound by the transport roller 7, and the leading end of the image receiving sheet is vacuum-suctioned and fixed on the recording drum 4 via a suction hole provided in the recording drum. 3) The squeeze roller 8 descends onto the recording drum 4 and stops while the image receiving sheet is further conveyed by a specified amount by rotation of the drum while holding down the image receiving sheet, and is cut to a specified length by the cutter 9. 4) The recording drum 4 further makes one revolution, and the loading of the image receiving sheet is completed. 5) Next, in the same sequence as the image receiving sheet, the first color-black thermal transfer sheet K is fed out from the thermal transfer sheet roll 10K, cut, and loaded. 6) Next, the recording drum 4 starts rotating at a high speed, the recording head 2 on the sub-scanning rail 3 starts to move, and when the recording head reaches a recording start position, the recording head 2 irradiates the recording laser onto the recording drum 4 according to the recording image signal. Is done. The irradiation ends at the recording end position, and the sub-scanning rail operation and the drum rotation stop. Return the recording head on the sub-scanning rail to the origin. 7) With the image receiving sheet left on the recording drum, only the thermal transfer sheet K is peeled off. Therefore, the front end of the thermal transfer sheet K is hooked with a nail and pulled out in the discharge direction, and is discarded from the discard port 32 to the discard box 35. 8) Repeat steps 5) to 7) for the remaining three colors. The recording order is black, followed by cyan, magenta, and yellow. That is, the second color-cyan thermal transfer sheet C is sequentially from the thermal transfer sheet roll 10C, the third color-magenta thermal transfer sheet M is from the thermal transfer sheet roll 10M, and the fourth color-yellow thermal transfer sheet Y is sequentially from the thermal transfer sheet roll 10Y. It is paid out. This is the opposite of the general printing order, because the color order on the paper is reversed by the paper transfer in a later step. 9) When the four colors are completed, the recorded image receiving sheet is finally discharged to the discharge table 31. The method of peeling off from the drum is the same as that of the thermal transfer sheet of 7), but unlike the thermal transfer sheet, it is not discarded. When the sheet is discharged to the discharge table, air 34 is blown from below the discharge port 33 to enable stacking of a plurality of sheets.

The transport roller 7 at any of the supply portion and the transport portion of the thermal transfer sheet roll and the image receiving sheet roll.
It is preferable to use an adhesive roller having an adhesive material disposed on the surface.

By providing the adhesive roller, 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 roller include ethylene-vinyl acetate copolymer and ethylene-vinyl acetate.
Ethyl acrylate copolymer, polyolefin resin, polybutadiene resin, styrene-butadiene copolymer (S
(BR), styrene-ethylene-butene-styrene copolymer (SEBS), acrylonitrile-butadiene copolymer (NBR), polyisoprene resin (IR), styrene-isoprene copolymer (SIS), acrylic ester copolymer , Polyester resin, polyurethane resin, acrylic resin, butyl rubber, polynorbornene and the like.

The surface of the adhesive roller can be cleaned by contacting the surfaces 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 roller 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) Here, P: magnitude of load (Kg), d: diagonal length of square of recess (mm).

Further, in the present invention, the adhesive material used for the above-mentioned adhesive roller has an elastic modulus at 20 ° C. of not more than 200 kg / cm ² (MP19.6 MPa). It is preferable because dust can be sufficiently removed and image defects can be suppressed.

The feature 2 of the systematization technique is the configuration of the thermal transfer device. The image receiving sheet on which the image is printed by the recording device,
A thermal transfer device is used to perform the process of transferring to printing paper (called “book paper”). This process is First Proof
Exactly the same as ^TM . When the image receiving sheet and the paper are overlapped and heat and pressure are applied, they adhere to each other, and then the image receiving film is peeled off from the paper, leaving only the image and the adhesive layer on the paper,
The image receiving sheet support and the cushion layer are peeled off. Therefore, practically, the image is transferred from the image receiving sheet to the actual paper.

In First Proof ^™ , the original paper and the image receiving sheet are superimposed on an aluminum guide plate and transferred by passing between heat rollers. The use of the aluminum guide plate is to prevent the paper from being deformed. However, if this is adopted in the present system of B2 size, there is a problem that an aluminum guide plate larger than B2 is required, and the installation space of the device becomes large. Therefore, this system does not use an aluminum guide plate, and adopts a structure in which the transport path is further rotated by 180 degrees and discharged to the insertion side, so that the installation space is extremely compact (Fig. 3). However, since the aluminum guide plate was not used, there was a problem that the paper was deformed.
Specifically, the pair of the discharged paper and the image receiving sheet curls with the image receiving sheet inside, and rolls on the discharge table. It is very difficult to peel off the image receiving sheet from the curled book. In view of the above, a method of preventing rounding is considered, and a bimetal effect due to a difference in shrinkage amount between the actual paper and the image receiving sheet, and an iron effect due to a structure wound around a heat roller. When the image receiving sheet is inserted on top of the actual paper as in the past, the thermal shrinkage of the image receiving sheet in the insertion direction is larger than the thermal shrinkage of the actual paper. Since the direction of the ironing effect is the same, the curl becomes severe due to the synergistic effect. However, if the image receiving sheet is inserted so as to be below the paper, the curl of the bimetal effect is downward and the curl of the iron effect is upward, so that the curl is canceled and no problem occurs.

The sequence of the paper transfer is as follows (hereinafter referred to as the paper transfer method used in the present system). The thermal transfer device 41 shown in FIG. 3 used in this method is a manual device unlike the recording device. 1) First, according to the type of book paper 42, heat roller 43
(100-110 ° C.) and the transfer speed during transfer are set with a dial (not shown). 2) Next, the image receiving sheet 20 is placed on the insertion table with the image facing up, and dust on the image is removed with a charge removing brush (not shown). The real paper 42 from which dust has been removed is laid thereon. At this time, since the size of the book paper 42 placed above the image receiving film 20 placed below is larger, the position of the image receiving sheet 20 becomes invisible and positioning is difficult. In order to improve the workability, a mark 45 indicating the placement position of each of the image receiving sheet and the book sheet is provided on the insertion table 44. The reason why the paper is larger is to prevent the image receiving sheet 20 from being displaced and protruding from the paper 42 to stain the heat roller 43 with the image receiving layer of the image receiving sheet 20. 3) When the sheet is inserted into the insertion slot with the image receiving sheet and the actual paper being overlapped, the insertion roller 46 rotates, and the two rollers are heated by the heat roller 43.
To send out. 4) When the leading end of the paper reaches the position of the heat roller 43, the heat roller is nipped and starts transfer. The heat roller is a heat-resistant silicon rubber roller. Here, by simultaneously applying pressure and heat, the image-receiving sheet and the paper are bonded. A guide 47 made of a heat-resistant sheet is installed downstream of the heat roller. It is peeled off from the heat roller and guided to the discharge port 50 along the guide plate 49. 5) The image receiving sheet / book sheet pair coming out of the discharge port 50 is discharged onto the insertion table while being bonded. Thereafter, the image receiving sheet 20 is peeled off from the main paper 42 by hand.

The feature 3 of the systematization technique is the system configuration. By connecting the above-described apparatus on a plate making system, a function as a color proof can be exhibited. As a system, it is necessary for a proof to output a print having an image quality as close as possible to the print output from certain platemaking data. Therefore, software for bringing colors and halftone dots closer to printed matter is required. A specific connection example will be introduced. Celebra ^TM manufactured by Fuji Photo Film Co., Ltd.
When the proof of the printed matter from the plate making system is taken, the system connection is as follows. Celebra
To a CTP (Computer To Plate) system. By applying the printing plate thus output to a printing machine, a final printed matter is obtained. Luxel FINALPROOF manufactured by Fuji Photo Film Co., Ltd.
5600 (hereinafter also referred to as FINALPROOF) is connected.Fuji Photo Film's PD system is used as proof drive software to bring colors and halftone dots closer to the printed matter.
Connect ^TM . Contone (continuous tone) data converted to raster data by Celebra is converted to binary data for halftone dots, output to a CTP system, and finally printed. On the other hand, the same contone data is also output to the PD system. The PD system converts the received data according to a four-dimensional (black, cyan, magenta, yellow) table so that the color matches the printed matter. Finally, the data is converted into binary data for halftone dots so as to match the halftone dots of the printed matter, and output to FINALPROOF (FIG. 4). The four-dimensional table is created experimentally in advance and stored in the system. The experiment for making is as follows. Important color data can be stored in an image printed via a CTP
Prepare an image output to FINALPROOF via the system, compare its colorimetric values, and create a table so that the difference is minimized.

As described above, according to the present invention, a system configuration capable of sufficiently exerting the ability of a material having a high resolution was realized.

Next, the thermal transfer sheet which is a material used in the system of the present invention will be described. The absolute value of the difference between the surface roughness Rz of the image forming layer surface of the thermal transfer sheet and the surface roughness Rz of the back layer surface thereof is 3.0 or less, and the surface roughness Rz of the image receiving layer surface of the image receiving sheet and the surface roughness Rz thereof. The absolute value of the difference in the surface roughness Rz is preferably 3.0 or less. With such a configuration, image defects can be prevented in combination with the above-described cleaning means, transport jams can be eliminated, and dot gain stability can be improved.

In this specification, the surface roughness Rz is defined 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. A probe-type three-dimensional roughness meter (Surfcom 570A-3DF) manufactured by Tokyo Seimitsu Co., Ltd. is used for the measurement. 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 as follows.
1.0 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 backside layer surface is 1.0.
The following is preferred from the viewpoint of further improving the above effects.

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

The glossiness of the image forming layer of the thermal transfer sheet is
It is also preferably 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 for use as an image forming layer for uniform and high-definition images, but high smoothness results in greater resistance during conveyance, and the two are in a trade-off relationship.
When the glossiness is in the range of 80 to 99, both can be compatible and the balance can be maintained.

Next, 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 the laser light is radiated imagewise in time from the support 12 side of the thermal transfer sheet 10 of the laminate 30, the laser light irradiated area of the photothermal conversion layer 14 of the thermal transfer sheet 10 generates heat, and the image forming layer 16 is heated.
And the adhesive strength with the film is reduced (FIG. 1B). After that, when the image receiving sheet 20 and the thermal transfer sheet 10 are peeled off, the laser light irradiated area 16 ′ of the image forming layer 16 becomes
0 is transferred onto the image receiving layer 24 (FIG. 1C).

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

The laser light to be used can be used without any particular limitation. Gas laser light such as argon ion laser light, helium neon laser light, helium cadmium laser light, solid laser light such as YAG laser light, semiconductor laser light Direct laser light such as dye laser light and 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 multi-color image forming method, considering output power and ease of modulation, etc.,
It is preferable to use semiconductor laser light. In the multicolor image forming method, it is preferable to irradiate the laser beam under the condition that the beam diameter on the light-to-heat conversion layer is in the range of 5 to 50 μm (particularly, 6 to 30 μm), and the scanning speed is 1 m.
/ Sec or more (especially 3 m / sec or more).

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

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

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

Diluting compound preparation conditions LDPE resin 58.3 g Calcium stearate 0.2 g Carbon black 40% by 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 for 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.
Regarding the latter, for example, a thermal transfer sheet having an image forming layer containing color materials having mutually different hues is prepared, and an image forming laminate obtained by combining this with an image receiving sheet is independently made of four types (four colors: Cyan, magenta, yellow and black). To each of the laminates, for example, through a color separation filter, perform laser light irradiation according to a digital signal based on the image, and subsequently, peel off the thermal transfer sheet and the image receiving sheet, color separation images of each color on each image receiving sheet Are formed independently. Next, each of the formed color separation images is
A multicolor image can be formed by sequentially laminating on an actual support such as a separately prepared printing paper or a similar support.

The thermal transfer sheet using laser beam irradiation is
It is preferable to form an image on an image receiving sheet by converting a laser beam into heat and using the thermal energy to form an image forming layer containing a pigment on an image receiving sheet by a thin film transfer method. The technology used in the development of the sheet-forming image forming material can be appropriately applied to the development of a thermal transfer sheet and / or an image receiving sheet such as a fusion transfer method, an ablation transfer method, and a sublimation transfer method. The inventive system can also include the imaging materials used in these systems.

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

(Support) The material of the support of the thermal transfer sheet is not particularly limited, and various support materials can be used according to the purpose. The support preferably has rigidity, good dimensional stability, and withstands heat during image formation. Preferred examples of the support material include polyethylene terephthalate, polyethylene-2,6-naphthalate, polycarbonate, polymethyl methacrylate, polyethylene,
Polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, styrene-acrylonitrile copolymer, polyamide (aromatic or aliphatic), polyimide,
Synthetic resin materials such as polyamide imide and polysulfone can be mentioned. Among them, biaxially stretched polyethylene terephthalate is preferable in consideration of mechanical strength and dimensional stability against heat. When a color proof is produced using laser recording, the support of the thermal transfer sheet is preferably formed of a transparent synthetic resin material that transmits laser light. The thickness of the support is 25 to 130 μm
Is preferably, and particularly preferably 50 to 120 μm. The center line average surface roughness Ra (measured based on JIS B0601 using a surface roughness measuring device (Surfcom, manufactured by Tokyo Seiki Co., Ltd.)) of the support on the image forming layer side may be less than 0.1 μm. preferable. The Young's modulus of the support in the longitudinal direction is 200 to 1200 kg / mm.
² (≒ ^{2 to} 12 GPa) is preferable, and the Young's modulus in the width direction is 250 to 1600 kg / mm ² (≒ 2.5 to 16 GPa).
a) is preferred. F-5 in the longitudinal direction of the support
The value is preferably 5 to 50 kg / mm ² ($ 49 to 49
0 MPa), and the F-5 value in the support width direction is preferably 3
３０30 kg / mm ² (≒ 29.4 to 294 MPa), and the F-5 value in the support longitudinal direction is F-5 in the support width direction.
It is generally higher than the value, but this is not particularly necessary when it is necessary to increase the strength in the width direction. Further, the heat shrinkage in the longitudinal direction and the width direction of the support at 100 ° C. for 30 minutes is preferably 3% or less, more preferably 1.5% or less, and the heat shrinkage at 80 ° C. for 30 minutes is preferably 1%. Less than,
More preferably, it is 0.5% or less. The breaking strength is 5 to 100 kg / mm ² (ｍｍ49 to 980 MP in both directions).
a), the elastic modulus is 100 to 2000 kg / mm ² (≒ 0.
98 to 19.6 GPa).

The support of the thermal transfer sheet 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 from 0.01 to 2 μm. Further, on the surface of the thermal transfer sheet opposite to the side on which the light-to-heat conversion layer is provided, various functional layers such as an anti-reflection layer and an anti-static layer can be provided or a surface treatment can be performed, if necessary.

(Back Layer) It is preferable to provide a back layer on the surface of the thermal transfer sheet of the present invention opposite to the side on which the light-to-heat conversion layer is provided. The back layer is composed of 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 / B 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 described.
A is less than 0.3. When B / A is 0.3 or more, the slipperiness and the powder drop of the back layer deteriorate.

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

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

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

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

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

In the first and second back layers, various additives and binders such as a surfactant, a slipping agent and a matting agent can be added in addition to the antistatic agent. The amount of the antistatic agent contained in the first back layer is preferably from 10 to 1,000 parts by mass, and more preferably from 200 to 80 parts by mass based on 100 parts by mass of the binder.
0 parts by mass is more preferred. The amount of the antistatic agent contained in the second back layer is preferably from 0 to 300 parts by mass, more preferably from 0 to 100 parts by mass, based on 100 parts by mass of the binder.

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

(Light-to-heat conversion layer) The light-to-heat conversion layer contains a light-to-heat conversion substance, a binder, and if necessary, a matting agent.
Further, if necessary, other components are contained. The photothermal conversion substance is a substance having a function of converting irradiated light energy into heat energy. 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, phthalocyanines, macrocyclic compound pigments having absorption in the visible to near-infrared region such as naphthalocyanine, and laser absorbing materials for high-density laser recording such as optical disks. Examples thereof include organic dyes (cyanine dyes such as indolenine dyes, anthraquinone dyes, azulene dyes, and phthalocyanine dyes), and organic metal compound dyes such as dithiol nickel complexes. 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, when the resin is heat-resistant and does not decompose even by the heat generated from the light-to-heat conversion material, even if high-energy light irradiation is performed, the surface of the light-heat conversion layer after light irradiation can be smoothed. It is preferable because it can be maintained. Specifically, the thermal decomposition temperature (T
A resin having a temperature of 10 ° C./min in a GA method (thermal mass spectrometry) at a temperature rising rate of 5% in an air stream at a temperature rising rate of 10 ° C./min. More preferred. Also, the binder is 200 to 400 ° C.
It preferably has a glass transition temperature of 250 to 35.
More preferably, it has a glass transition temperature of 0 ° C. When the glass transition temperature is lower than 200 ° C., fogging may occur in an image to be formed, and when the glass transition temperature is higher than 400 ° C., the solubility of the resin may be reduced and the production efficiency may be reduced.
In addition, it is preferable that the heat resistance (for example, heat deformation temperature and thermal decomposition temperature) of the binder of the light-to-heat conversion layer is higher than that of the material used for the other layers provided on the light-to-heat conversion layer.

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

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

[0091]

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

[0093]

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[0094]

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

[0096]

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[0097]

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

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

The matting agent contained in the light-to-heat conversion layer includes inorganic fine particles and organic fine particles. Examples of the inorganic fine particles include silica, titanium oxide, aluminum oxide, zinc oxide, magnesium oxide, barium sulfate, magnesium sulfate, aluminum hydroxide, magnesium hydroxide, metal salts such as boron nitride, kaolin, clay, talc, zinc oxide, and the like. Examples include lead white, ziglite, quartz, diatomaceous earth, barlite, bentonite, mica, and synthetic mica. Examples of the organic fine particles include fluorine resin particles, guanamine resin particles, acrylic resin particles, styrene-acryl copolymer resin particles, silicone resin particles, melamine resin particles, and epoxy resin particles.

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

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

The light-to-heat conversion layer is prepared by dissolving a light-to-heat conversion substance and a binder, preparing a coating solution containing a matting agent and other components as necessary, coating the solution on a support, and drying. Can be provided. Examples of the organic solvent for dissolving the polyimide resin include, for example, n
-Hexane, cyclohexane, diglyme, xylene,
Toluene, ethyl acetate, tetrahydrofuran, methyl ethyl ketone, acetone, cyclohexanone, 1,4-dioxane, 1,3-dioxane, dimethyl acetate,
N-methyl-2-pyrrolidone, dimethylsulfoxide, dimethylformamide, dimethylacetamide, γ
-Butyrolactone, ethanol, methanol and the like. Coating and drying can be performed by using ordinary coating and drying methods. Drying is usually performed at a temperature of 300 ° C. or lower, preferably at a temperature of 200 ° C. or lower. When polyethylene terephthalate is used as the support, drying is preferably performed at a temperature of 80 to 150 ° C.

When the amount of the binder in the light-to-heat conversion layer is too small, the cohesive force of the light-to-heat conversion layer 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.
26 is preferable because the transfer sensitivity of the image forming layer is improved.
It is more preferable to have fifteen. If the wavelength at 808 nm 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 during recording, and fog may occur.

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

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

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

3) Cyan pigment Pigment Blue (Pigment Blue) 15
(C.I. No. 74160) Example) Lionol Blue 7
027 (manufactured by Toyo Ink Manufacturing Co., Ltd.), Fastogen
Blue (fastogen blue) BB (manufactured by Dainippon Ink and Chemicals, Inc.) Pigment Blue (pigment blue) 1
5: 1 (CI No. 74160) Example) Hosterperm Blue (Hoster Palm Blue) A2R (manufactured by Clariant Japan KK),
Fastogen Blue (fastogen blue)
5050 (manufactured by Dainippon Ink and Chemicals, Inc.) Pigment Blue 1
5: 2 (CI No. 74160) Example) Hosterperm Blue (Hoster Palm Blue) AFL (manufactured by Clariant Japan KK),
Irgalite Blue (Irgalite Blue)
BSP (Ciba Specialty Chemicals Co., Ltd.)
Pigment Blue (Pigment Blue) 1 Fastogen Blue (Fastgen Blue) GP (Dai Nippon Ink Chemical Industry Co., Ltd.)
5: 3 (CI No. 74160) Example) Hosterperm Blue (Hoster Palm Blue) B2G (manufactured by Clariant Japan K.K.),
Lionol Blue 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.)
Co., Ltd.), Lionogen Blue (Lionogen Blue) 6501 (manufactured by Toyo Ink Mfg. Co., Ltd.)

4) Black Pigment Pigment Black (Pigment Black)
7 (carbon black CI No. 77266) Example) Mitsubishi carbon black MA100 (manufactured by Mitsubishi Chemical Corporation), Mitsubishi carbon black # 5 (manufactured by Mitsubishi Chemical Corporation), Black Pearls (Black Pearls) 430 (Cabot) Co. (Cabot Corporation)
Pigments that can be used in the present invention include “Pigment Handbook, edited by Japan Pigment Technical Association, Seibundo Shinkosha, 198
9 ”,“ COLOUR INDEX, THE SOCIETY OF DYES & COL ”
OURIST, THIRD EDITION, 1987 "and the like, and can appropriately select a product.

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 0.03 μm or more, the dispersion cost does not increase, and the dispersion does not cause gelation or the like,
On the other hand, when the thickness is 1 μm or less, coarse particles do not exist in the pigment, so that the adhesion between the image forming layer and the image receiving layer is good, and the transparency of the image forming layer can be improved.

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, homopolymers and copolymers of substituted products, methacrylates such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and hydroxyethyl methacrylate And acrylates such as methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate and α-ethylhexyl acrylate, and dienes such as acrylic acid, butadiene and isoprene; Use of vinyl monomers such as rilonitrile, vinyl ethers, maleic acid and maleic esters, maleic anhydride, cinnamic acid, vinyl chloride, vinyl acetate, or copolymers with other monomers Can be. These resins can be used as a mixture of two or more kinds.

The softening point referred to here is a Vicat softening point, which can be measured by a Vicat softening point measuring device manufactured by Toyo Seiki Co., Ltd. (measurement conditions: load 1 kg, heating rate 50)
° C / hr, penetration 1 mm).

The image forming layer preferably contains the pigment in an amount of 20 to 80% by mass, more preferably 30 to 70% by mass, and particularly preferably 30 to 50% by mass. . The image forming layer preferably contains 80 to 20% by mass, more preferably 70 to 30% by mass, and more preferably 70 to 40% by mass of the amorphous organic high molecular polymer. It is particularly preferred that

The image forming layer can contain the following components as the other components. still,
Each of the components (1) to (4) may be contained in any one of the coating layers of the thermal transfer sheet and the image receiving sheet, and is particularly preferably contained in the image forming layer. Examples of the wax include mineral waxes, natural waxes, and synthetic waxes. Examples of the mineral wax include petroleum wax such as paraffin wax, microcrystalline wax, ester wax, and oxidized wax, montan wax, ozokerite, and ceresin.
Among them, paraffin wax is preferred. The paraffin wax is separated from petroleum, and various types are commercially available depending on the melting point. Examples of the natural waxes include vegetable waxes such as carnauba wax, wood wax, ouriculi wax, and spal wax, and animal waxes such as beeswax, insect wax, shellac wax, and whale wax.

The synthetic wax is generally used as a lubricant and usually comprises a higher fatty acid compound. Examples of such synthetic waxes include the following. 1) Fatty acid-based wax Linear saturated fatty acid represented by the following general formula: CH ₃ (CH ₂ ) _n COOH In the above formula, n represents an integer of 6 to 28. Specific examples include stearic acid, behenic acid, palmitic acid, 12-hydroxystearic acid, azelaic acid and the like.
In addition, metal salts such as the above fatty acids (eg, K, Ca, Z
n, Mg, etc.). 2) Fatty acid ester-based wax Specific examples of the fatty acid ester include ethyl stearate, lauryl stearate, ethyl behenate, hexyl behenate, and behenyl myristate. 3) Fatty acid amide-based wax When a fatty acid amide is used, it is more preferable to use a fatty acid amide of a saturated fatty acid and a fatty acid amide of an unsaturated fatty acid in combination. Specific examples of amides whose fatty acid moiety is a saturated fatty acid include stearic amide, lauric amide, palmitic amide, behenic amide, myristic amide and the like. Specific examples of the amide of an unsaturated fatty acid having a fatty acid moiety include oleic acid amide and erucic acid amide. Examples of other fatty acid amides also include substituted amides such as bisamide and methylolamide. 4) Aliphatic alcohol wax A linear saturated aliphatic alcohol represented by the following general formula: CH ₃ (CH ₂ ) _n OH In the above formula, n represents an integer of 6 to 28. Specific examples include stearyl alcohol.

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

Plasticizer As the plasticizer, an ester compound is preferable, and dibutyl phthalate, di-n-octyl phthalate, and di (2
-Ethylhexyl), dinonyl phthalate, dilauryl phthalate, butyl lauryl phthalate, butyl benzyl phthalate and the like; aliphatic diesters such as di (2-ethylhexyl) adipate and di (2-ethylhexyl) sebacate Known plasticizers such as phosphate esters such as basic acid esters, tricresyl phosphate, and tri (2-ethylhexyl) phosphate, polyol polyesters such as polyethylene glycol esters, and epoxy compounds such as epoxy fatty acid esters are exemplified. 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.

The ester compounds of acrylic acid or methacrylic acid include monomethacrylate, monoacrylate, dimethacrylate, diacrylate, trimethacrylate, triacrylate, tetramethacrylate,
Tetraacrylate and the like can be mentioned. Specifically, polyethylene glycol dimethacrylate, 1,2,4-butanetriol trimethacrylate, trimethylolethane triacrylate, pentaerythritol acrylate, pentaerythritol tetraacrylate, dipentaerythritol-polyacrylate, etc., or the following general formula (1) )) Or a homo- or copolymer containing the monomer as a main component. General formula (1) R ₁ R ₂ R ₃ C—CH ₂ —OCO—CR = C
In the formula H ₂ , R ₁ , R ₂ and R ₃ are each a hydrogen atom or a lower alkyl group (methyl group, ethyl group, propyl group, butyl group, etc.)
Or —CH ₂ —OCO—CR ＝ CH ₂ , and R represents a hydrogen atom or a methyl group.

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

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

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

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

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, 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 themselves decompose or degrade due to heat to generate gas, and compounds that absorb or adsorb a considerable amount of easily vaporizable gas such as water (polymer). Or a low molecular compound). These may be used in combination.

Examples of the polymer which is decomposed or deteriorated 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 compounds such as polyisobutyl methacrylate in which volatile compounds such as water are adsorbed, cellulose esters such as ethyl cellulose in which volatile compounds such as water are adsorbed, and volatile compounds such as water. Natural polymer compounds such as adsorbed gelatin can be exemplified. Examples of the low molecular weight compound which decomposes or degrades by heat to generate a gas include a compound which generates a gas upon exothermic decomposition such as a diazo compound or azide. In addition, the decomposition or deterioration of the heat-sensitive material due to heat as described above preferably occurs at 280 ° C. or lower, particularly preferably at 230 ° C. or lower.

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

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 image forming layers are laminated in this order, the heat-sensitive release layer decomposes and degrades due to heat transmitted from the light-to-heat conversion layer to generate gas. Then, due to the decomposition or the generation of gas, the heat-sensitive peeling layer partially disappears, or cohesive failure occurs in the heat-sensitive peeling layer, and the bonding force between the light-heat conversion layer and the image forming layer decreases. For this reason, depending on the behavior of the heat-sensitive release layer, a part of the heat-sensitive release layer adheres to the image forming layer and appears on the surface of the finally formed image, which may cause color mixing of the image. Therefore, even when such transfer of the heat-sensitive release layer occurs, the heat-sensitive release layer is hardly colored, that is, high in visible light, so that no visual color mixture appears in the formed image. It is desirable to show permeability. Specifically, the light-absorbing rate of the heat-sensitive release layer is 50% or less, preferably 1 to visible light.
0% or less. In addition, instead of providing an independent heat-sensitive release layer on the thermal transfer sheet, the heat-sensitive material is added to a light-to-heat conversion layer coating solution to form a light-to-heat conversion layer. It can also be set as a structure.

The coefficient of static friction of the outermost layer on the side where the image forming layer of the thermal transfer sheet is coated is preferably 0.35 or less, more preferably 0.20 or less. By setting the coefficient of static friction of the outermost layer to 0.35 or less, it is possible to eliminate roll contamination when the thermal transfer sheet is conveyed, and to improve the quality of the formed image. The method for measuring the coefficient of static friction is described in Japanese Patent Application No. 2000-85759.
The method described in paragraph (0011) is followed. In the present invention, the smoother value of the image forming layer surface is 2.2 to 50 mm at 23 ° C. and 55% RH.
Hg (≒ 0.293 to 6.65 kPa), and Ra is 0.
It is preferably from 0.5 to 0.4 μm. As a result, a large number of microscopic voids where the image receiving layer and the image forming layer cannot contact the contact surface can be reduced, which is preferable in terms of transfer and further image quality. The Ra value is measured by a surface roughness measuring device (Surfco
m, manufactured by Tokyo Seiki Co., Ltd.)
Can be measured based on The surface hardness of the image forming layer is preferably 10 g or more 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 preferably 10 ⁹ Ω or less at 23 ° C. and 55% RH.

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

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

[0130] It is preferable that the support has minute voids (voids) because the image quality can be improved. Such a support may be, for example, a thermoplastic resin, a mixed melt obtained by mixing a filler made of an inorganic pigment or a polymer incompatible with the thermoplastic resin or the like, a single layer or a multilayer by a melt extruder. It can be produced by forming a film and further stretching it uniaxially or biaxially. In this case, the porosity is determined by the selection of the resin and the filler, the mixing ratio, the stretching conditions, and the like.

As the thermoplastic resin, a polyolefin resin such as polypropylene and a polyethylene terephthalate resin are preferable because of good crystallinity, good stretchability, and easy formation of voids. It is preferable to use the polyolefin resin or the polyethylene terephthalate resin as a main component, and appropriately use a small amount of another thermoplastic resin in combination. As the inorganic pigment used as the filler, those having an average particle diameter of 1 to 20 μm are preferable, and calcium carbonate, clay, diatomaceous earth, titanium oxide, aluminum hydroxide, silica and the like can be used. When polypropylene is used as the thermoplastic resin as the incompatible resin used as the filler, it is preferable to combine polyethylene terephthalate as the filler. The details of the support having minute voids (voids) are described in JP-A-2001-105752. still,
The content of the filler such as an inorganic pigment in the support is generally about 2 to 30% by volume.

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

(Image-Receiving Layer) It is preferable to provide one or more image-receiving layers on a support in order to transfer and fix the image-forming layer on the surface of the image-receiving sheet. The image receiving layer is preferably a layer formed mainly of an organic polymer binder. The binder is preferably a thermoplastic resin, for example, acrylic acid, methacrylic acid,
Acrylic esters, homopolymers of acrylic monomers such as methacrylic esters and copolymers thereof, methyl cellulose, ethyl cellulose, cellulose polymers such as cellulose acetate, polystyrene, polyvinylpyrrolidone, polyvinyl butyral, polyvinyl alcohol, polyvinyl chloride, etc. And homopolymers and copolymers of vinyl monomers such as polyesters, condensation polymers such as polyesters and polyamides, and rubber polymers such as butadiene-styrene copolymers.
The binder of the image receiving layer is preferably a polymer having a glass transition temperature (Tg) lower than 90 ° C. in order to obtain a proper adhesive strength with the image forming layer. For this purpose, a plasticizer can be added to the image receiving layer. Further, the binder polymer preferably has a Tg of 30 ° C. or higher in order to prevent blocking between sheets. In order to improve the adhesion to the image forming layer at the time of laser recording and to improve the sensitivity and image strength, at least one of the monomer units as a component of the binder polymer of the image receiving layer includes a binder of the image forming layer. Those which are the same as at least one of the monomer units constituting the polymer are preferred.

In the present invention, the smoother value of the image receiving layer surface is
0.5-50mmHg at 23 ℃, 55% RH (≒ 0.0665 ～ 6.65kPa)
And Ra is preferably 0.05 to 0.4 μm. This makes it possible to reduce the number of microscopic voids in which the image receiving layer and the image forming layer cannot contact the contact surface,
It is preferable in terms of transfer and further image quality. The Ra value can be measured based on JIS B0601 using a surface roughness measuring device (Surfcom, manufactured by Tokyo Seiki Co., Ltd.) or the like. 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 of the surface of the image receiving layer is preferably 0.2 or less. The surface energy of the image receiving layer surface is 23 to 35 mg / m
It is preferably ² .

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

Examples of the organic polymer include the polymer for forming an image receiving layer. In addition, as the photopolymerization initiator, a general photoradical polymerization initiator such as benzophenone, Michler's ketone or the like is used in a ratio of 0.1 to 20% by mass in the layer.

The thickness of the image receiving layer is 0.3 to 7 μm, preferably 0.7 to 4 μm. When the thickness is 0.3 μm or more, the film strength can be ensured at the time of retransfer to the printing paper. By setting the thickness to 4 μm or less, the gloss of the image after the re-transfer of the paper is suppressed,
The closeness to printed matter is improved.

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

The cushion layer is easily deformed when a stress is applied to the image receiving layer. To achieve the above-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 preferably 0.5 MPa to 1.0 GPa, particularly preferably 1 MPa to 0.5 GPa, and more preferably 10 to 100 GPa.
MPa. In addition, in order to allow foreign matter such as dust to be sunk, the penetration (25
(C, 100 g, 5 seconds) is preferably 10 or more. Further, the glass transition temperature of the cushion layer is 80 ° C. or less, preferably 25 ° C. or less, and the softening point is preferably 50 to 200 ° C. It is also possible to suitably add a plasticizer to the binder to adjust these physical properties, for example, Tg.

Specific materials used as 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. Although the thickness of the cushion layer varies depending on the resin used and other conditions, it is usually 3 to 100 μm,
Preferably it is 10 to 52 μm.

The image receiving layer and the cushion layer need to be adhered to each other up to the stage of laser recording. However, in order to transfer the image to the printing paper, it is preferable that the image receiving layer and the cushion layer are provided in a releasable manner. In order to facilitate peeling, it is also preferable to provide a peeling layer having a thickness of about 0.1 to 2 μm between the cushion layer and the image receiving layer. If the layer thickness is too large, the performance of the cushion layer becomes difficult to appear, so it is necessary to adjust the thickness depending on the type of the release layer. Specific examples of the binder for the release layer include polyolefin, polyester, polyvinyl acetal, polyvinyl formal, polyparabanic acid, polymethyl methacrylate, polycarbonate, ethyl cellulose, nitrocellulose, methylcellulose, carboxymethylcellulose, hydroxypropylcellulose, polyvinyl alcohol, and polyvinyl chloride. , Urethane resin,
Tg of fluorine-based resin, styrenes such as polystyrene, acrylonitrile styrene and the like, and those obtained by cross-linking these resins, polyamide, polyimide, polyetherimide, polysulfone, polyethersulfone, and aramid have a Tg of 65 ° C.
The above-mentioned thermosetting resins and cured products of these resins are included. As the curing agent, a general curing agent such as isocyanate and melamine can be used.

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

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

The image receiving sheet to be combined with the thermal transfer sheet may have a structure in which the image receiving layer also serves as a cushion layer. / Cushioning image receiving layer may be used. Also in this case, it is preferable that the cushioning image-receiving layer is provided so as to be releasable so that it can be retransferred to the printing paper. In this case, the image after retransfer to the printing paper becomes an image having excellent gloss. The thickness of the cushioning image receiving layer is 5 to 100 μm, preferably 10 to 100 μm.
４０40 μm.

It is preferable to provide a back layer on the surface of the support opposite to the surface on which the image receiving layer is provided, since the transportability of the image receiving sheet is improved. It is preferable to add an antistatic agent such as a surfactant and tin oxide fine particles and a matting agent such as silicon oxide and PMMA particles to the back layer in terms of improving the transportability in the recording apparatus. The additives can be added not only to the back layer but also to the image receiving layer and other layers as needed. Although the type of additive cannot be specified unconditionally depending on the purpose,
For example, in the case of a matting agent, particles having an average particle size of 0.5 to 10 μm can be added to the layer in an amount of about 0.5 to 80%. As the antistatic agent, the surface resistance of the layer is 23 ° C., 50
10 ¹² Ω or less, more preferably 10 ⁹ Ω under the condition of% RH
As described below, it can be appropriately selected and used from various surfactants and conductive agents.

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

As the matting agent preferably added to the back layer, organic or inorganic fine particles can be used. As an organic matting agent, polymethyl methacrylate (PMM
A), polystyrene, polyethylene, polypropylene,
Other examples include fine particles of a radical polymerizable polymer, and fine particles of a condensation polymer such as polyester and polycarbonate. The back layer is preferably provided with a coverage of about 0.5 to 5 g / m ² . If it is less than 0.5 g / m ² , the coating properties are unstable and problems such as powder dropping of the matting agent are likely to occur.
Further, when the coating is applied more than 5 g / m ² , the particle size of the suitable matting agent becomes very large, and the image receiving layer surface is embossed by the back layer during storage, and especially the thermal transfer for transferring the thin image forming layer. In this case, missing or unevenness of a recorded image is likely to occur. The matting agent preferably has a number average particle size that is larger by 2.5 to 20 μm than the layer thickness of only the binder in the back layer. Among the matting agents, particles having a particle size of 8 μm or more require 5 mg / m ² or more, and preferably 6 to 600 mg / m ^2.
a m ^2. This improves, in particular, foreign object failure.
The value σ / r is obtained by dividing the standard deviation of the particle size distribution by the number average particle size.
By using a material having a narrow particle size distribution such that n (= coefficient of variation of the particle size distribution) is 0.3 or less, defects caused by particles having an abnormally large particle size can be improved.
Desired performance can be obtained with a smaller amount of addition. This coefficient of variation is more preferably 0.15 or less.

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

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

The thermal transfer sheet and the image receiving sheet can be used for image formation as a laminate in which the image forming layer of the thermal transfer sheet and the image receiving layer of the image receiving sheet are overlapped. The laminate of the thermal transfer sheet and the image receiving sheet can be formed by various methods. For example, it can be easily obtained by stacking the image forming layer of the thermal transfer sheet and the image receiving layer of the image receiving sheet and passing them through a pressure and heating roller. The heating temperature in this case is preferably 160 ° C. or lower, or 130 ° C. or lower.

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

[0152]

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

(Example 1) -Preparation of thermal transfer sheet K (black)-[Formation of back layer] [Preparation of back first layer coating solution] Aqueous dispersion of acrylic resin 2 parts (Julima-ET410, 20% by mass) Antistatic agent 7.0 parts (water dispersion of tin oxide-antimony oxide, average particle size: 0.1 μm, 17% by mass) Polyoxyethylene phenyl ether 0.1 part Melamine compound 0.3 part (Sumitex Resin M-3, manufactured by Sumitomo Chemical Co., Ltd.) Distilled water was prepared so that the total would be 100 parts.

[Formation of Back First Layer] A biaxially stretched polyethylene terephthalate support having a thickness of 75 μm (Ra on both sides)
Is subjected to a corona treatment on one side (rear side) of the back layer. The first layer coating solution is applied to a dry layer thickness of 0.03 μm and dried at 180 ° C. for 30 seconds. Was formed. The Young's modulus in the longitudinal direction of the support is 450 kg / m.
m ² (≒ 4.4 GPa) and the Young's modulus in the width direction is 500
Kg / mm ² (≒ 4.9 GPa). The F-5 value in the longitudinal direction of the support is 10 kg / mm ² (≒ 98 MP
a) The F-5 value in the width direction of the support is 13 kg / mm
² (≒ 127.4 MPa), 100 ° C.
The heat shrinkage in 30 minutes is 0.3% in the longitudinal direction and 0.1% in the width direction. The breaking strength is 20 kg / mm in the longitudinal direction.
² (≒ 196 MPa) and the width direction is 25 kg / mm ² (≒
245 MPa) and the elastic modulus is 400 kg / mm ² (≒ 3.
9 GPa).

[Preparation of Back Layer Second Layer Coating Solution] Polyolefin 3.0 parts (Chemipearl S-120, 27% by mass, manufactured by Mitsui Petrochemical Co., Ltd.) Antistatic agent 2.0 parts (tin oxide-antimony oxide aqueous dispersion, Average particle size: 0.1 μm, 17% by mass) Colloidal silica 2.0 parts (Snowtex C, 20% by mass, manufactured by Nissan Chemical Co., Ltd.) Epoxy compound 0.3 parts (Dinacol Ex614B, manufactured by Nagase Kasei Co., Ltd.) Polystyrene sulfonic acid Sodium 0.1 part Distilled water Prepared so that the total would be 100 parts.

[Formation of Back Second Layer] A back second layer coating solution was applied on the back first layer so as to have a dry film thickness of 0.03 μm, and dried at 170 ° C. for 30 seconds. Was formed.

[Formation of Light-to-Heat Conversion Layer] [Preparation of Light-to-Heat Conversion Layer Coating Solution] The following components were mixed while stirring with a stirrer to prepare a light-to-heat conversion layer coating solution. [Composition of coating solution for photothermal conversion layer]-7.6 parts of infrared absorbing dye ("NK-2014" manufactured by Hayashibara Biochemical Laboratory Co., Ltd., cyanine dye having the following structure)

[0158]

Embedded image

(Wherein R represents CH ₃ and X ⁻ represents ClO ₄ ⁻ ) 29.3 parts of polyvinyl butyral (“PVB-2000L”, manufactured by Denki Kagaku Kogyo KK) • Exxonnaphtha 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-based surfactant)-The following composition 14.1 parts of matting agent dispersion Preparation of matting agent dispersion 10 parts of true spherical silica fine particles (Seahoster KE-P150 manufactured by Nippon Shokubai Co., Ltd.) having an average particle size of 1.5 μm, and a dispersing agent polymer (acrylate styrene copolymer) Polymer: 2 parts of Juncryl 611 (manufactured by Johnson Polymer Co., Ltd.), 16 parts of methyl ethyl ketone and 64 parts of N-methylpyrrolidone, and 30 parts of glass beads having a diameter of 2 mm 2 hours dispersed to obtain a dispersion of silica fine particles in a paint shaker (manufactured by Toyo Seiki) is are in a polyethylene container having a capacity of 200 ml.

[Formation of Light-to-Heat Conversion Layer on Support Surface] The above-mentioned coating solution for a light-to-heat conversion layer was applied to one surface of a polyethylene terephthalate film (support) having a thickness of 75 μm using a wire bar. The coated material was dried in an oven at 120 ° C. for 2 minutes to form a light-to-heat conversion layer on the support. The obtained light-to-heat conversion layer had an absorption at a wavelength of about 808 nm, and its absorbance (optical density: OD _LH ) was measured with a UV-spectrophotometer UV-240 manufactured by Shimadzu Corporation.
D _LH = 1.03. When the cross section of the light-to-heat conversion layer was observed with a scanning electron microscope, the layer thickness was 0.3 on average.
μm.

[Formation of Image Forming Layer] [Preparation of Coating Solution for Black Image Forming Layer] The following components were placed in a kneader mill, and a pre-dispersion treatment was carried out by adding a small amount of solvent and applying a shearing force. Was. The dispersion was further added with a solvent, and finally prepared to have the following composition,
Sand mill dispersion was performed for 2 hours to obtain a pigment dispersion mother liquor. [Black pigment dispersion mother liquor composition] Composition 1-12.6 parts of polyvinyl butyral ("PVB-2000L", manufactured by Denki Kagaku Kogyo KK)-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) -Propyl alcohol 79.4 parts Composition 2-Polyvinyl butyral 12.6 parts ("PVB-2000L", manufactured by Denki Kagaku Kogyo KK)-Pigment Black 7 (Carbon Black CI No. 77266) 10.5 parts ("Mitsubishi Carbon Black MA100", manufactured by Mitsubishi Chemical Corporation, PVC blackness: 10) -0.8 parts of dispersing aid ("Solsperse S-20000", manufactured by ICI Corporation)-79.4 parts of n-propyl alcohol

Next, the following components were mixed while stirring with a stirrer to prepare a coating solution for a black image forming layer. [Coating solution 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 ("PVB-2000L", manufactured by Denki Kagaku Kogyo Co., Ltd.・ Wax-based compound (Stearic acid amide “Neutron 2”, manufactured by Nippon Seika Co., Ltd.) 1.7 parts (Behenic acid amide “Diamid BM”, manufactured by Nippon Kasei Co., Ltd.) 1.7 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 “Diamid” L-200 "(manufactured by Nippon Kasei Co., Ltd.) 1.7 parts (oleic acid amide" Diamid O-200 ", manufactured by Nippon Kasei Co., Ltd.) 1.7 parts Rosin 11.4 parts (" KE-311 Arakawa Chemical (Component: resin acid 80-97%; resin acid component: abietic acid 30-40%, neoabietic acid 10-20%, dihydroabietic acid 14%, tetrahydroabietic acid 14%) Surfactant 2 1 part (“MegaFac F-176PF”, solid content 20%, manufactured by Dainippon Ink & Chemicals, Inc.) 7.1 parts inorganic pigment (“MEK-ST”, 30% methyl ethyl ketone solution, Nissan Chemical Co., Ltd.)・ N-propyl alcohol 1050 parts ・ Methyl ethyl ketone 295 parts The particles in the obtained coating liquid for a black image forming layer were measured with a laser scattering type particle size distribution analyzer to find that the average particle diameter was 0.25 μm. And the ratio of particles of 1 μm or more was 0.5%.

[Formation of Black Image Forming Layer on Surface of Light-to-Heat Conversion Layer] The above-mentioned coating solution for a black image forming layer was applied to the surface of the light-to-heat conversion layer for 1 minute using a wire bar, and the coated material was heated to 100 ° C. Dried in the 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) in which a light-to-heat conversion layer and a black image forming layer are provided on a support in this order.
This is referred to as a thermal transfer sheet K. Similarly, a sheet provided with the yellow image forming layer and the image forming layer is referred to as a thermal transfer sheet Y, a sheet provided with the magenta image forming layer is referred to as a thermal transfer sheet M, and a sheet provided with the cyan image forming layer is referred to as a thermal transfer sheet C).
Was prepared. 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-
904 "(W filter), OD =
0.91. 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. The surface smoother value is 9.3 mm at 23 ° C. and 55% RH.
Hg (≒ 1.24 kPa). The coefficient of static friction of the surface is preferably 0.2 or less, specifically 0.08. The surface energy was 29 mJ / m ^2. The contact angle of water was 94.8 °. The reflection optical density was 1.82, the film thickness was 0.60 μm, and OD _r / film thickness (in μm) was 3.03. The light intensity of the exposure surface is 1000W / mm ²
The deformation ratio of the photothermal conversion layer when recording at a linear velocity of 1 m / sec or more with the above laser light was 168%.

—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 ("PVB-2000L", manufactured by Denki Kagaku Kogyo KK)-Pigment Yellow 180 (C.I. 21290) 12.9 parts ("Novoperm Yellow (Novo Palm Yellow) P-HG", manufactured by Clariant Japan KK)-Dispersing aid 0.6 part ("Solsperse S-20000", manufactured by ICI Corporation) 79.4 parts of n-propyl alcohol [Yellow pigment dispersion mother liquor composition] Yellow pigment composition 2: 7.1 parts of polyvinyl butyral ("PVB-2000L", manufactured by Denki Kagaku Kogyo KK)-Pigment Yellow (Pigment Yellow) 139 (CINO 56298) 12.9 parts ("No. Operm Yellow (Novo palm yellow) M2R 70 ", manufactured by Clariant Japan Co., Ltd.) Dispersion aid 0.6 parts (" SOLSPERSE S-20000 ", ICI Co., Ltd.) n-propyl alcohol 79.4 parts

[Coating solution 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 ("PVB-2000L") , Denki Kagaku Kogyo Co., Ltd.)-Wax compound (stearic amide "Neutron 2", manufactured by Nippon Seika Co., Ltd.) 0.7 parts (behenic amide "Diamid BM", Nippon Kasei Co., Ltd.) )) 0.7 parts (lauric amide “Diamid Y”, manufactured by Nippon Kasei Co., Ltd.) 0.7 parts (palmitic amide “Diamit KP”, manufactured by Nippon Kasei Co., Ltd.) 0.7 parts ( 0.7 parts of oleic acid amide "Diamid L-200", manufactured by Nippon Kasei Co., Ltd. 0.7 parts (oleic amide "Diamid O-200", manufactured by Nippon Kasei Co., Ltd.) Nonionic surfactant Agent 0.4 part ("Chemistat 1100", manufactured by Sanyo Chemical Co., Ltd.) ・ Rosin 2.4 parts ("KE-311", Arakawa Chemical Co., Ltd.) ・ 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. The surface smoother value is 2.3 mm at 23 ° C. and 55% RH.
Hg (≒ 0.31 kPa). The coefficient of static friction of the surface is preferably 0.2 or less, specifically 0.1.
The surface energy was 24 mJ / m ^2. The contact angle of water was 108.1 °. The reflection optical density is 1.01, the film thickness is 0.42 μm, and OD _r / film thickness (μm unit)
Was 2.40. The deformation ratio of the light-to-heat conversion layer was 150% when recording was performed at a linear velocity of 1 m / sec or more with a laser beam having a light intensity of 1000 W / mm ² or more on the exposed surface.

-Preparation of Thermal Transfer Sheet M- The preparation of the thermal transfer sheet K was the same as the preparation of the thermal transfer sheet K except that the coating solution for the magenta image forming layer having the following composition was used instead of the coating solution for the black image forming layer. In the same manner as in the above, a thermal transfer sheet M was produced. The 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 ("PVB-2000L", manufactured by Denki Kagaku Kogyo KK)-Pigment Red 57: 1 (CI No.) .1 5850: 1) 15.0 parts ("Symuller Brilliant Carmine 6B-229", manufactured by Dainippon Ink and Chemicals, Inc.)-Dispersing aid 0.6 parts ("Solsperse S-20000") 80.4 parts of n-propyl alcohol [Magenta pigment dispersed mother liquor composition] Magenta pigment composition 2; 12.6 parts of polyvinyl butyral ("PVB-2000L", manufactured by Denki Kagaku Kogyo KK) -Pigment Red (Pigment Red) 57: 1 (CI No. 15) 850: 1) 15.0 parts (“Lionol Red (Lionol Red) 6B-4290G”, manufactured by Toyo Ink Manufacturing Co., Ltd.) ・ 0.6 parts of dispersion aid (“Solsperse S-20000”, ICI Corporation) 7) part of n-propyl alcohol

[Coating liquid composition for magenta image forming layer] 163 parts of magenta pigment dispersed mother liquor Magenta pigment composition 1: magenta pigment composition 2 = 95: 5 (parts) Polyvinyl butyral 4.0 parts (“PVB-2000L”) , Denki Kagaku Kogyo Co., Ltd.)-Wax compound (Stearic amide "Neutron 2", manufactured by Nippon Seika Co., Ltd.) 1.0 part (Behenamide "Diamid BM", 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”, manufactured by Nippon Kasei Co., Ltd.) 1.0 part (Erka Acid amide "Diamind L-200", Nippon Kasei Co., Ltd.) 1.0 part (Oleic acid amide "Diamid O-200", Nippon Kasei Co., Ltd.) 1.0 part Nonionic surfactant 0.7 parts (“Chemistat 1100”, manufactured by Sanyo Chemical Co., Ltd.) 4.6 parts of rosin (“KE-311”, manufactured by Arakawa Chemical Co., Ltd.) 2.5 parts of pentaerythritol tetraacrylate (“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 resulting 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. The surface smoother value is 3.5 mm at 23 ° C. and 55% RH.
Hg (≒ 0.47 kPa). The coefficient of static friction of the surface is preferably 0.2 or less, specifically 0.08. The surface energy was 25 mJ / m ^2. The contact angle of water was 98.8 °. The reflection optical density was 1.51, the film thickness was 0.38 μm, and OD _r / film thickness (in μm) was 3.97. The light intensity of the exposure surface is 1000W / mm ²
The deformation ratio of the photothermal conversion layer when recording at a linear velocity of 1 m / sec or more with the above laser light was 160%.

-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 preparing 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 ("PVB-2000L", manufactured by Denki Kagaku Kogyo KK)-Pigment Blue (Pigment Blue) 15: 4 (CI No. 74160) 15.0 parts (“Cyanine Blue (Cyanine Blue) 700-10FG”, manufactured by Toyo Ink Mfg. Co., Ltd.) ・ Dispersing aid 0.8 parts (“PW-36”, manufactured by Kusumoto Kasei Co., Ltd.) 110 parts of n-propyl alcohol [Cyan pigment dispersed mother liquor composition] Cyan pigment composition 2: 12.6 parts of polyvinyl butyral ("PVB-2000L", manufactured by Denki Kagaku Kogyo KK)-Pigment Blue (Pigment Blue) 15 (CI No. 74 160) 15.0 parts ("Lionol Blue" 70 27 ", manufactured by Toyo Ink Manufacturing Co., Ltd. ・ Dispersing aid 0.8 parts (“ PW-36 ”, manufactured by Kusumoto Kasei Co., Ltd.) ・ n-propyl alcohol 110 parts

[Composition of Cyan Image Forming Layer Coating Solution] 118 parts of the above-mentioned cyan pigment-dispersed mother liquor Cyan pigment composition 1: cyan pigment composition 2 = 90: 10 (parts) 5.2 parts of polyvinyl butyral (“PVB-2000L”) 1.3 parts of inorganic pigment "MEK-ST" Wax compound (stearic amide "Neutron 2", manufactured by Nippon Seika Co., Ltd.) 1.0 part (behenic acid) Amide "Diamid BM", manufactured by Nippon Kasei Co., Ltd. 1.0 part (Lauramide amide "Diamid Y", manufactured by Nippon Kasei Co., Ltd.) 1.0 part (Palmitic acid amide "Diamind KP", Nippon Kasei 1.0 part (erucamide "Diamid L-200" (Nippon Kasei Co., Ltd.)) 1.0 part (oleic amide "Diamid O-200", Nippon Kasei Co., Ltd.) 1.0 part ・ Rosin 2.8 parts (“KE-311”, Arakawa Chemical Co., Ltd.) ・ Pentaerythritol tetraacrylate 1.7 parts (“NK ester A-TMMT”, Shin-Nakamura Chemical Co., Ltd.) -1.7 parts of surfactant ("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. The smoother value of the surface is 7.0 mm at 23 ° C. and 55% RH.
Hg (≒ 0.93 kPa). The coefficient of static friction of the surface is preferably 0.2 or less, specifically 0.08. The surface energy was 25 mJ / m ^2. The contact angle of water was 98.8 °. The reflection optical density was 1.59, the film thickness was 0.45 μm, and OD _r / film thickness (in μm) was 3.53. The light intensity of the exposure surface is 1000W / mm ²
The deformation ratio of the photothermal conversion layer when recording at a linear velocity of 1 m / sec or more with the above laser light was 165%.

-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 8 parts of polyvinyl butyral ("PVB-2000L", manufactured by Denki Kagaku Kogyo KK)-0.7 parts of antistatic agent ("Sunstat 2012A", Sanyo Chemical Industries, Ltd.) )) ・ Surfactant 0.1 part (“MegaFac F-177”, manufactured by Dainippon Ink & Chemicals, Inc.) ・ n-propyl alcohol 20 parts ・ Methanol 20 parts ・ 1-methoxy-2-propanol 50 Department

Using a small width applicator, a white PET support (“Lumirror # 130E58”, manufactured by Toray Industries, Inc., thickness 1)
30 μm), the above-mentioned coating solution for forming a cushion layer is applied, the coating layer is dried, and then a coating solution for an image receiving layer is applied.
Dried. The thickness of the cushion layer after drying is about 20 μm,
The coating amount was adjusted so that the thickness of the image receiving layer was about 2 μm. The white PET support is a laminate of a void-containing polyethylene terephthalate layer (thickness: 116 μm, porosity: 20%) and titanium oxide-containing polyethylene terephthalate layers (thickness: 7 μm, titanium oxide content: 2%) provided on both sides thereof. (Total thickness: 130 μm, specific gravity: 0.8) is a void-containing plastic support. The produced material was wound up in a roll form, stored at room temperature for one week, and then used for image recording with the following laser beam. The physical properties of the obtained image receiving layer were as follows. Surface roughness Ra 0.4-0.01
μm was preferred, and specifically 0.02 μm. The undulation on the surface of the image receiving layer was preferably 2 μm or less, specifically 1.2 μm. The smoother value of the surface of the image receiving layer is 0.8 mmHg at 23 ° C. and 55% RH (≒ 0.11 kP
a). The coefficient of static friction of the surface of the image receiving layer is preferably 0.8 or less, and specifically 0.37. The surface energy of the surface of the image receiving layer was 29 mJ / m ² . The contact angle of water was 87.0 °.

-Formation of Transferred Image- The image forming system uses a Luxel FINALPROOF5600 as a recording device in the system shown in FIG. Was. The image-receiving sheet (56 cm × 79 cm) prepared above was wound around a rotating drum having a diameter of 38 cm having a vacuum section hole having a diameter of 1 mm (one area density in an area of 3 cm × 8 cm), and was vacuum-adsorbed. Next, the thermal transfer sheet K (black) cut into a size of 61 cm × 84 cm was overlapped so as to evenly protrude from the image receiving sheet, and squeezed by a squeeze roller, and adhered and laminated so that air was sucked into the section holes. The degree of pressure reduction when the section hole is closed is -150 mmHg (Ｈ81.1) with respect to 1 atm.
3 kPa). The drum is rotated, and a semiconductor laser beam having a wavelength of 808 nm is condensed from the outside onto the surface of the laminated body on the drum so as to form a 7 μm spot on the surface of the photothermal conversion layer. (Scanning direction), while moving in the direction perpendicular to (scanning direction),
Laser image (image) recording was performed on the laminate. Laser irradiation conditions are as follows. The laser beam used in this embodiment was a multi-beam two-dimensional laser beam consisting of five parallel lines in the main scanning direction and three parallel lines in the sub-scanning direction. Laser power 110 mW Main scanning speed 500 rpm Sub-scanning pitch 6.35 μm Ambient temperature / humidity 18 ° C 30%, 23 ° C 50%, 26 ° C 65% 3 conditions The diameter of the exposure drum is preferably 360 mm or more, specifically 380 mm. Was used. The image size is 51
5 mm x 728 mm, resolution is 2600 dpi.
When 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, only the light irradiation area of the image forming layer of the thermal transfer sheet K was transferred from the thermal transfer sheet K to the image receiving sheet. It was confirmed that it was.

In the same manner as described above, the thermal transfer sheets Y,
From each of the thermal transfer sheets M and C, an image was transferred onto an image receiving sheet. The transferred four-color image was further transferred to recording paper to form a multi-color image.
Even when laser recording was performed with high energy using a laser beam having a dimensional array, a multicolor image having good image quality and a stable transfer density could be formed. 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.

Example 2 In Example 1, the polyvinyl butyral used for the image forming layer and the image receiving layer (“PV
B-2000L ", manufactured by Denki Kagaku Kogyo Co., Ltd.) was replaced with polyvinyl butyral (" BL-SH ", manufactured by Sekisui Chemical Co., Ltd.) to form a transfer image in the same manner as in Example 1. did.

Example 3 In Example 1, the polyvinyl butyral used for the image forming layer and the image receiving layer (“PV
A transfer image was formed in the same manner as in Example 1, except that "B-2000L", manufactured by Denki Kagaku Kogyo KK) was changed to a styrene-based resin ("SMA3840", manufactured by Kawahara Yuka Co., Ltd.). Example 4 In Example 1, the polyvinyl butyral (“PVB-2000”) used for the image forming layer and the image receiving layer was used.
L ", manufactured by Denki Kagaku Kogyo Co., Ltd.) except that the image forming layer was changed to a styrene-acrylonitrile-acrylate copolymer resin and the image receiving layer was changed to a styrene-acrylate copolymer resin. A multicolor image forming material was prepared in the same manner as in Example 1, and a transfer image was formed.

Comparative Example 1 In Example 1, the polyvinyl butyral used for the image forming layer and the image receiving layer (“PV
B-2000L "(manufactured by Denki Kagaku Kogyo KK), and polyvinyl butyral (" PVB-20 ") for the image forming layer.
00L "(manufactured by Denki Kagaku Kogyo KK) and a styrene resin (" SMA3840 ", Kawahara Yuka Co., Ltd.) for the image receiving layer.
Was used. Otherwise, a transfer image was formed in the same manner as in Example 1.

Comparative Example 2 In Example 1, the polyvinyl butyral used for the image forming layer and the image receiving layer (“PV
B-2000L ", manufactured by Denki Kagaku Kogyo Co., Ltd .; a styrene resin (" SMA3840 ", manufactured by Kawahara Yuka Co., Ltd.) for the image forming layer; and a polyvinyl butyral (" PVB-2000L ") for the image receiving layer. ", Manufactured by Denki Kagaku Kogyo Co., Ltd.). Otherwise, a transfer image was formed in the same manner as in Example 1.

The evaluation of the image obtained by such a system configuration was performed as follows. (1) Measurement of Reflection Optical Density (OD _r ) and Calculation of Image Transfer Ratio The reflection optical density (OD _r ) of the image forming layer was obtained by further transferring the image transferred from the thermal transfer sheet to the image receiving sheet to Tokishi art paper. The color was measured with a densitometer (X-rite938, manufactured by X-rite) in each color mode such as yellow (Y), magenta (M), cyan (C) or black (K).

[0184]

[Table 1]

The thermal transfer sheet K was transferred onto an image receiving sheet without laser recording using a thermal transfer apparatus, and the reflection density (OD) of the obtained black image was measured by the above method. The image transfer rate by laser recording was 18% 30%, 23 ° C 50%, 2%.
98.4% and 9 under the temperature and humidity conditions of 6 ° C and 65%, respectively.
6.8% and 96.3%.

(2) Sensitivity One laser line was recorded and evaluated at 150 times magnification using an optical microscope. The evaluation criteria are as follows. Table 2 shows the evaluation results. ： １: 1 line is recorded without interruption Δ: 1 line is partially interrupted ×: most of the line is not transferred

(3) Image quality When the solid portion and the line drawing portion of the transferred image were observed with an optical microscope using the four-color thermal transfer sheet, no gap was observed in the solid portion under any environmental conditions. In addition, the resolution of the line drawing was a good result, and a black transfer image with little dependence on environmental conditions could be obtained. The evaluation of the image quality was visually performed according to the following criteria. Table 2 shows the evaluation results. -Solid part-A: No gap or defective transfer during recording. Δ: There are gaps and poor transfer at the time of recording. X: A gap at the time of recording or transfer failure exists on the entire surface. -Line drawing part-A: The edge of the line drawing is sharp and has good resolution. Δ: The edge of the line drawing is jagged, and bridging has occurred partially. ×: Bridging has occurred entirely.

(4) Paper Transfer Property The image receiving sheet on which the image was transferred from the thermal transfer sheet and art paper were placed on a laminator (heat roller temperature 130 ° C., 39.degree.
Pressurized with 2MPa compressed air, v = 0.3m / min)
After the temperature was returned to room temperature, the image receiving sheet and the art paper were peeled off to transfer the image receiving layer. The evaluation criteria are as follows.
Table 2 shows the evaluation results. ：: All images are transferred without unevenness. 少 し: There is a little image and glitter. ×: Some transfer residue is left.

[0189]

[Table 2]

(5) Dot Shape The image obtained in the example formed a dot image corresponding to the number of print lines at a resolution of 2400 to 2540 dpi. Each halftone dot has almost no blurring or chipping and is very sharp in shape, so that a high range of halftone dots from highlights to shadows could be clearly formed (FIGS. 5 to 12). as a result,
High-quality halftone dot output was possible at the same resolution as the image setter and the CTP setter, and halftone dots and gradation with good print similarity were reproduced (FIGS. 13 and 14). 2600dpi
The product obtained good results even with the above resolution.

(6) Character quality Since the image obtained in the embodiment has a sharp dot shape,
Fine lines of fine characters were clearly reproduced (FIGS. 15 and 1).
6).

The proof product developed in the present invention is based on the thin film transfer technology, and incorporates the above-mentioned various technologies in order to solve new problems in the laser thermal transfer system and achieve higher image quality. A laser thermal transfer recording system for DDCP that realizes sharp halftone dots by the thin film thermal transfer method, and consists of paper transfer, actual halftone output, pigment type, B2 size image forming material, output machine, and high-quality CMS software. We were able to develop. As described above, according to the present invention, a system configuration capable of sufficiently exerting the ability of a material having a high resolution can be realized. Specifically, we can provide a contract proof that replaces proofs and analog color proofs in response to filmlessness in the CTP era. 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, paper transfer is possible, and the same pigment-based coloring material as the printing ink is used, and a large size (A2 / B2
As described above, a digital direct color proof system can be provided. The present invention uses a laser thin-film thermal transfer system, uses a pigment coloring material, performs actual halftone dot recording, and can transfer the actual paper. Under different temperature and humidity conditions, by using a laser beam that is a multi-beam two-dimensional array, and also when performing laser recording with high energy, the image quality is good, and an image with a stable transfer density can be formed on the image receiving sheet. A multicolor image forming material and a multicolor image forming method can be provided. In particular, the present invention can enhance the adhesion between the image forming layer and the image receiving layer during laser transfer recording, and can improve the recording sensitivity, image quality, and paper transferability.

[Brief description of the drawings]

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

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

FIG. 3 is a diagram illustrating a configuration example of a thermal transfer device.

FIG. 4 is a diagram illustrating a configuration example of a system using a recording device for laser thermal transfer FINALPROOF.

FIG. 5 shows a dot shape of an image obtained in the example. The distance between the dot centers is 125 μm.

FIG. 6 shows a dot shape of an image obtained in the example. The distance between the dot centers is 125 μm.

FIG. 7 shows a dot shape of an image obtained in the example. The distance between the dot centers is 125 μm.

FIG. 8 shows a dot shape of an image obtained in the example. The distance between the dot centers is 125 μm.

FIG. 9 shows a dot shape of an image obtained in the example. The distance between the dot centers is 125 μm.

FIG. 10 shows a dot shape of an image obtained in the example.
The distance between the dot centers is 125 μm.

FIG. 11 shows a dot shape of an image obtained in the example.
The distance between the dot centers is 125 μm.

FIG. 12 shows a dot shape of an image obtained in the example.
The distance between the dot centers is 125 μm.

FIG. 13 shows a dot shape of an image obtained in the example.
The distance between the dot centers is 125 μm.

FIG. 14 shows dot reproducibility of an image obtained in an example. The vertical axis indicates the dot area ratio calculated from the reflection density, and the horizontal axis indicates the dot area ratio of the input signal.

FIG. 15 shows two points of character quality of an image obtained in the example. Shows a positive image.

FIG. 16 shows two points of character quality of an image obtained in the example. Shows a negative image.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 recording apparatus 2 recording head 3 sub-scanning rail 4 recording drum 5 thermal transfer sheet loading unit 6 image receiving sheet roll 7 transport roller 8 squeeze roller 9 cutter 10 thermal transfer sheet 10K, 10C, 10M, 10Y thermal transfer sheet roll 12 support 14 photothermal conversion layer Reference Signs List 16 image forming layer 20 image receiving sheet 22 image receiving sheet support 24 image receiving layer 30 laminated body 31 discharge stand 32 waste port 33 discharge port 34 air 35 waste box 42 book paper 43 heat roller 44 insertion table 45 mark indicating placement position 46 insertion Roller 47 Guide made of heat-resistant sheet 48 Peeling claw 49 Guide plate 50 Discharge port

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

Claims (3)

[Claims] 1. An image receiving sheet having an image receiving layer, and a thermal transfer sheet having at least four or more different colors including yellow, magenta, cyan, and black having at least a light-to-heat conversion layer and an image forming layer on a support, The image forming layer of each thermal transfer sheet and the image receiving layer of the image receiving sheet are superposed facing each other, irradiated with laser light, and the laser light irradiated area of the image forming layer is transferred onto the image receiving layer of the image receiving sheet to record an image. In the multicolor image forming material, the reflection optical density (OD _r ) and the film thickness (μm) of the image forming layer of each thermal transfer sheet are
Ratio OD _r / thickness of the unit) is not less than 1.50, the recording area of each thermal transfer sheet of the multi-color image is 515 mm × 72
8 mm or more, and the resolution of the transferred image is 2
400 dpi or more, at least one monomer unit constituting the binder of the image forming layer and at least one monomer unit constituting the binder of the image receiving layer are the same, and the smoother value of the surface of the image receiving layer is 0. 0.5 to 50 mmHg, and the smoother value of the surface of the image forming layer is 2.2 to 50 mmHg. 2. The multicolor image forming material according to claim 1, wherein the monomer unit of the binder is any one of a vinyl acetal unit, a styrene unit, a butyral unit and a styrene acrylate unit. 3. An image receiving sheet having an image receiving layer, and a thermal transfer sheet having at least four or more different colors including yellow, magenta, cyan, and black having at least a light-to-heat conversion layer and an image forming layer on a support, The image forming layer of each thermal transfer sheet and the image receiving layer of the image receiving sheet are superposed facing each other, irradiated with laser light, and the laser light irradiated area of the image forming layer is transferred onto the image receiving layer of the image receiving sheet to record an image. 3. A multicolor image forming method according to claim 1, wherein
A multicolor image forming method, characterized by using the multicolor image forming material described in (1).