JP3429284B2 - Multicolor image forming material, multicolor image forming method, and multicolor image forming apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor image forming material, a multicolor image forming method and a multicolor image forming apparatus for forming a high resolution full color image by using a laser beam. In particular, the present invention uses a laser recording from a digital image signal to perform color proofing (DDCP:
The present invention relates to a multicolor image forming material, a multicolor image forming method, and a multicolor image forming apparatus which are useful for producing a direct digital color proof) or a mask image.

[0002]

2. Description of the Related Art In the field of graphic arts, printing plates are printed using a set of color separation films made from color originals using lith films, but in general, this printing (actual printing work) In order to check for errors in the color separation process and the need for color correction, the color proof is made from the color separation film. Color proofs are required to have high resolution that enables high reproducibility of halftone images and high process stability. Further, in order to obtain a color proof similar to an actual printed matter, a material used for the actual printed matter is used as the material used for the color proof, for example, a printing paper is used as the base material and a pigment is used as the coloring material. It is preferable. Also,
As a method for producing a color proof, there is a strong demand for a dry method that does not use a developing solution.

As a dry color proof manufacturing method, a recording system for directly manufacturing a color proof from a digital signal has been developed with the spread of an electronic system in a pre-printing step (prepress field). The purpose of such an electronic system is to produce a high-quality color proof, and generally reproduces a halftone dot image of 150 lines / inch or more. In order to record a high-quality proof 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. Therefore, it is necessary to develop an image-forming material that exhibits high recording sensitivity to laser light and high resolution capable of reproducing 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, and a wax and a binder in which a pigment is heat-meltable are used as a support. There is known a hot-melt transfer sheet (JP-A-5-58045) having an image forming layer dispersed in the above components in this order. In the image forming method using these image forming materials, the image forming layer corresponding to the laser light irradiation region of the photothermal conversion layer melts by the heat generated in the region and is transferred onto the image receiving sheet laminated on the transfer sheet. Then, a transfer image is formed on the image receiving sheet.

Further, in Japanese Unexamined Patent Publication No. 6-219052, a photothermal conversion layer containing a photothermal conversion substance, a very thin layer (0.03 to 0.3 μm) of a heat release layer, and a coloring material are provided on a support. A thermal transfer sheet in which an image forming layer containing the same is provided in this order is disclosed. In this thermal transfer sheet, the binding force between the image forming layer and the photothermal conversion layer, which are bound by the interposition of the thermal release layer, is reduced by being irradiated with laser light, 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". Specifically, in a region irradiated with laser light, the thermal peeling layer partially decomposes and vaporizes, so that region The phenomenon in which the bonding force between the image forming layer and the photothermal conversion layer is weakened and the image forming layer in that region is transferred to the image receiving sheet laminated thereon is used.

In these image forming methods, it is possible to use a printing main paper provided with an image receiving layer (adhesive layer) as the image receiving sheet material, and to transfer a multicolor image by successively transferring images of different colors onto the image receiving sheet. An image forming method utilizing ablation has an advantage that a high-definition image can be easily obtained, and color proof (DDCP: direct digital color proof), Alternatively, it is useful for producing a high-definition mask image.

As the DTP environment advances, CTP (Computer To Plat
e) The need for proofing and analog proofing has increased from the proofing and analog proofing to the proofing needs of the users, and in recent years it has become even more high-quality and highly stable and has excellent print consistency. Large DDCP is desired. The laser thermal transfer system is capable of printing with high resolution, and conventionally there are systems such as a laser sublimation system, a laser ablation system, and a laser melting system, but all of them have a problem that the recording dot shape is not sharp. Since the laser sublimation method uses a dye as a coloring material, the approximation of the printed matter is not sufficient, and because the coloring material sublimes, the outline of the halftone dots is blurred and the resolution is not high enough. there were. On the other hand, the laser ablation method uses a pigment as a coloring material and thus has a good approximation to the printed matter. There was a problem that it was not expensive. 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 problems in the prior art and achieve the following objects. That is, the first object of the present invention is to provide a large size DDCP which has high quality and high stability and is excellent in printing consistency. Specifically, the present invention is: 1) The thermal transfer sheet is a pigment color. Even when compared with materials and printed materials, it is not affected by the illumination light source,
Transferring the color material thin film, the halftone dots are excellent and the stability is excellent.
2) The image-receiving sheet should be able to stably and reliably receive the image forming layer of the laser energy thermal transfer sheet. 3) Art (coated) paper, matte paper, lightly coated paper, etc.
It is possible to transfer the actual paper corresponding to the range of 157 g / m ² , be able to depict a delicate texture and accurately reproduce the white paper (high key portion), and 4) to obtain extremely stable transfer peeling property. A multicolor image forming material capable of forming an image with a stable transfer density on an image receiving sheet, which has a good image quality even when laser recording is performed with high energy by multi-beam laser light under different temperature and humidity conditions. A first object is to provide a multicolor image forming method and a multicolor image forming apparatus.

A second object of the present invention is to form a multi-color image which can prevent deterioration of image quality due to foreign matter entering the recording device when the image receiving sheet and the thermal transfer sheet are supplied to the recording device. A material, a multicolor image forming method, and a multicolor image forming apparatus.

[0010]

[Means for Solving the Problems] Means for solving the above problems are as follows. Multi claim 1, wherein
The color image forming method uses an image receiving sheet having an image receiving layer and at least four or more types of thermal transfer sheets having at least a photothermal conversion layer and an image forming layer on a support, and the image forming layer of each thermal transfer sheet and the image receiving sheet. Of the image receiving layer of the image forming layer is transferred to the image receiving layer of the image receiving sheet by irradiating with a laser beam .
Further, an image forming layer transferred onto the image receiving layer of the image receiving sheet.
In the multicolor image forming method, which comprises the step of transferring the image onto a sheet of paper to record an image, the thermal transfer sheet comprises at least four types of thermal transfer sheets of yellow, magenta, cyan, and black, and the image forming layer of each thermal transfer sheet.
Is directly above the photothermal conversion layer, and the ratio O of the optical density (OD) of the image forming layer of each thermal transfer sheet to the layer thickness (unit: μm).
D / layer thickness is 1.50 or more, the recording area of the multicolor image of each thermal transfer sheet is 515 mm × 728 mm or more, the resolution of the transferred image is 2400 dpi or more, and the laser beam of the photothermal conversion layer is For the irradiation area,
The cross-sectional area after image recording (a), the cross-sectional area before image recording
When (b), the deformation rate = {(a + b) / (b)}
X100 is 110% or more, and the laser light irradiation area is
The image forming layer in the area is transferred to the image receiving sheet in a thin film state, and the order of recording each thermal transfer sheet on the image receiving sheet is black, cyan, magenta, and yellow, and
From the image-receiving sheet to the main paper, in order from the support on the main paper
The yellow, magenta, cyan, and black image forming layers are transferred.
It is characterized by making it. The multicolor image forming method according to claim 2 , wherein after the image-receiving sheet is transferred to the main paper, the yellow, magenta, cyan, and black image forming layers are transferred in order from the support on the main paper. . Claim 3
The multicolor image forming method described above, the yellow, magenta,
It is characterized in that four or more types of thermal transfer sheets of cyan and black and an image receiving sheet are supplied in a roll state to a recording apparatus, and the respective sheets are fed out and automatically conveyed in the recording apparatus. The multicolor image forming method according to claim 4 ,
The transfer image is an image having a resolution of 2600 dpi or more. The multicolor image forming method according to claim 5 , wherein the optical density (O) of the image forming layer of each thermal transfer sheet is
D) and the layer thickness (unit: μm), the ratio OD / layer thickness is 1.80 or more. 7. The multicolor image forming method according to claim 6 , wherein a ratio OD of the optical density (OD) of the image forming layer of each of the thermal transfer sheets to the layer thickness (in μm) / layer thickness is 2.50.
The above is characterized. The multicolor image forming method according to claim 7 , wherein the contact angles of water of the image forming layers of the thermal transfer sheets and the image receiving layers of the image receiving sheets are 7.0 to 1.
It is characterized by being in the range of 20.0 degrees. The multicolor image forming method according to claim 8 , wherein a recording area of the multicolor image is 5
It is characterized by having a size of 98 × 841 mm or more. The multicolor image forming method according to claim 0 , wherein the ratio OD / layer thickness of the optical density (OD) and the layer thickness (in μm unit) of the image forming layer of each of the thermal transfer sheets is 1.80 or more, and the image receiving sheet. The contact angle with respect to water is 86 degrees or less. The multicolor image forming apparatus according to claim 10 , wherein an image receiving sheet having an image receiving layer and at least four or more types of thermal transfer sheets having at least a photothermal conversion layer and an image forming layer on a support are used, and an image of each thermal transfer sheet is formed. superposing a layer and image receiving layer of the image receiving sheet to face, by irradiating a laser beam, you image recording by transferring a thin film state laser light irradiation area of the image forming layer to the image-receiving sheet of the image receiving layer in the multi-color image forming apparatus, wherein the thermal transfer sheet is at least yellow, magenta, cyan, and four or more thermal transfer sheet of black, the image of each thermal transfer sheet
The forming layer is immediately above the light-heat converting layer, and the optical density (OD) and the layer thickness (μm unit) of the image forming layer of each thermal transfer sheet.
Ratio OD / layer thickness of 1.50 or more, the recording area of the multicolor image of each thermal transfer sheet is 515 mm × 728 mm or more, and the resolution of the transferred image is 2400 d.
pi or more, and the laser light irradiation area of the photothermal conversion layer
Then, the cross-sectional area after image recording is (a)
When the product is (b), the deformation rate = {(a + b) /
(B)} × 100 is 110% or more, and the order of recording the thermal transfer sheets on the image receiving sheet is black, cyan, magenta, and yellow, and the thermal transfer sheet and the image receiving sheet are in a roll state. And a sheet conveying unit for feeding and automatically conveying each of the supplied sheets.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of diligent examination of a recording system which provides a large size DDCP of B2 / A2 or higher, and B1 / A1 or higher, which has high quality and high stability and is excellent in print consistency,
A laser thermal transfer recording system for DDCP comprising an image forming material of B2 size or more of real paper transfer / actual halftone dot output / pigment type and an output machine and high quality CMS software was obtained.

The characteristics of the performance of this laser thermal transfer recording system, the system configuration and the outline of the technical points are as follows. The characteristic of the performance is that the dot shape is sharp, so it is possible to reproduce halftone dots with excellent printed material approximation. The hue is close to the printed matter. Since the recording quality is not easily affected by environmental temperature and humidity and the repeatability is good, a stable proof can be created. The technical points of materials that can obtain such characteristics of performance are establishment of thin film transfer technology, improvement of vacuum adhesion retention of materials required for laser thermal transfer system, follow-up to high resolution recording, and heat resistance. Is. Specifically, thinning the photothermal conversion layer by introducing an infrared absorbing dye, strengthening the heat resistance of the photothermal converting layer by introducing a high Tg polymer, stabilizing the hue by introducing a heat resistant pigment, wax, Examples thereof include controlling the adhesive force / cohesive force by adding a low-molecular component such as an inorganic pigment, and imparting vacuum adhesion without deterioration of image quality by adding a matting material to the photothermal conversion layer. The technical points of the system are air conveyance for continuous integration of multiple recording devices, thermal transfer device insertion on paper for curl reduction after transfer, connection of general-purpose output driver with system connection expandability, etc. To be As described above, the laser thermal transfer recording system is composed of various performance characteristics, system configurations and technical points. However, these are merely examples, and the present invention is not limited to these means.

In addition, individual materials, light-heat conversion layers, thermal transfer layers, coating layers such as image receiving layers, and thermal transfer sheets and image receiving sheets do not individually exist but function organically and comprehensively. This system has been developed based on the idea that these image-forming materials are combined with a recording device or a thermal transfer device to achieve the best performance. In this way, each coating layer of the image forming material and the constituent materials are carefully examined, and a coating layer that maximizes the features of those materials is created. This is used as the image forming material, and this image forming material has the best performance. We have found a suitable range of various physical properties to exert As a result, the relationship between each material, each coating layer, each sheet and physical characteristics is maximized, and further, the image forming material and the recording device or the thermal transfer device are organically connected,
It was possible to find a high-performance image forming material by making it function comprehensively. The positioning of the present invention in this system is an essential technique for defining the combination of the recording order and the fully automatic roll supply for extracting the characteristics of the high-performance image forming material that supports the system.

In order to form a normal color image, it is necessary to laminate at least four color image forming layers of yellow, magenta, cyan and black on the main paper. When four color image forming layers are laminated on the main paper in the order of yellow, magenta, cyan, and black in this order, as in the present invention,
The black color of the obtained image is very clear and the image quality is good. This is a great advantage especially in the case of a high resolution image having a resolution of 2400 dpi or more. The OD / layer thickness of the present invention is the ratio of the optical density of the image forming layer to the thickness of the image forming layer measured in “μm”. The optical density mentioned here is a reflection optical density measured by a Macbeth densitometer TD-904 (manufactured by Macbeth Co.). However, yellow, magenta, and cyan are measured by filters of respective colors, and black is measured by a W filter. The layer thickness of the image forming layer is measured by observing the cross section of the thermal transfer sheet before image recording with a scanning electron microscope. By setting the OD / layer thickness to 1.5 or more, an image having high optical density and good resolution can be obtained. O
If the D / layer thickness is less than 1.5, a sufficient optical density cannot be obtained, or the resolution is lowered, and a good image cannot be obtained in any case. The effect can be further promoted by setting the specific OD / layer thickness to 1.80 or more.
/ By setting the layer thickness to 2.50 or more, the transfer density and resolution can be greatly increased.

In the present invention, it is preferable that the thermal transfer sheet and the image receiving sheet are supplied in a roll form to the recording apparatus and are completely automatically conveyed therein. The term "fully automatic" as used herein means a method in which a person sets the thermal transfer sheet and the image receiving sheet in the recording apparatus, but thereafter, the operation up to the completion of recording is performed without any human hands. In the present invention, a thermal transfer sheet and an image receiving sheet are faced to each other and overlapped with each other and irradiated with laser light to form a recorded image. At that time, if a foreign substance is present between the thermal transfer sheet and the image receiving sheet, the transfer of the image forming layer is disturbed and a white spot-shaped non-transfer portion, so-called "white spot" is generated, which greatly deteriorates the image quality. By making it fully automatic, it is possible to prevent the entry of minute foreign matter such as dust into the recording device.
Such deterioration of image quality can be prevented. In general, the probability that a failure due to the above-mentioned foreign matter will occur in one screen is proportional to the image area, so white spots become a practical problem when the image area is large. In particular, in the case of an image having an area of 515 mm × 728 mm or more, the white spot becomes a very serious problem, but by making it “fully automatic”, a good image with very little white spot can be obtained.

The contact angle of water between the image forming layer of the thermal transfer sheet and the image receiving layer of the image receiving sheet of the present invention is preferably 7 to 120 degrees. When the contact angle is out of this range, the image forming layer is difficult to transfer to the image receiving layer, and the image quality is deteriorated. In the present invention, the contact angle means the contact angle of distilled water measured using a contact angle meter CA-A type (manufactured by Kyowa Interface Science Co., Ltd.).

Next, the entire system including the contents of the present invention will be described below. The system of the present invention has achieved high resolution and high image quality by inventing and adopting the thin film thermal transfer system. The system of the present invention has a resolution of 24
The system is capable of obtaining a transferred image of 00 dpi or more, preferably 2600 dpi or more. The thin film thermal transfer system is a system in which a thin film image forming layer having a film thickness of 0.01 to 0.9 μm is transferred to an image receiving sheet in a state where it is not partially melted or in a state where it is hardly melted. That is, since the recorded portion is transferred as a thin film, extremely high resolution can be obtained. A preferable method for efficiently performing thin film thermal transfer is to deform the inside of the photothermal conversion layer into a dome shape by optical recording, push up the image forming layer, enhance the adhesion between the image forming layer and the image receiving layer, and facilitate transfer. is there. If this deformation is large, the force that presses the image forming layer against the image receiving layer is large, which facilitates transfer.On the other hand, if the deformation is small, the force that presses the image forming layer onto the image receiving layer is small, and there are portions where sufficient transfer cannot be performed. come. Therefore, the preferable deformation for thin film transfer can be expressed as follows. For example, laser microscope (VK85
No. 00, manufactured by KEYENCE CORPORATION), the magnitude of this deformation shows that the cross-sectional area (a) of the recording part of the photothermal conversion layer after the optical recording is increased and that of the recording part of the photothermal conversion layer before the optical recording. The value obtained by adding the area (b) is divided by the cross-sectional area (b) of the recording portion of the photothermal conversion layer before optical recording, and the deformation rate can be evaluated by multiplying by 100. That is, deformation rate = {(a + b) /
(B)} × 100. The deformation rate is 110% or more, preferably 125% or more, and more preferably 150% or more. If the breaking elongation is increased, the deformation rate may be higher than 250%, but normally it is preferable to suppress it 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 storability In order to achieve high image quality, it is necessary to transfer a thin film on the order of submicrons, but in order to obtain the desired concentration, it is necessary to create a layer in which the pigment is dispersed in a high concentration. , And the thermal response is contrary. Further, the thermal responsiveness has a contradictory relationship with the storability (adhesion). We solved these conflicts by developing new polymers and additives. 2. Securing high vacuum adhesion In thin film transfer that pursues high resolution, it is preferable that the transfer interface be smooth, but this does not provide sufficient vacuum adhesion.
Regardless of the conventional wisdom of giving vacuum adhesion, by adding a large amount of matting agent with a relatively small particle size to the layer below the image forming layer, an appropriate gap between the thermal transfer sheet and the image receiving sheet can be kept uniform. , There is no omission of the image due to the matting agent,
Vacuum adhesion was imparted while maintaining the characteristics of thin film transfer. 3. Use of heat-resistant organic material The photothermal conversion layer that converts laser light into heat during laser recording is about 700 ° C, and the image forming layer containing pigment coloring material is about 500 ° C.
Reaching ℃. While developing a modified polyimide that can be applied to an organic solvent as a material for the light-heat conversion layer, it has higher heat resistance than a printing pigment as a pigment colorant, and is safe and has a hue.
Developed a pigment. 4. Ensuring surface cleanliness In thin film transfer, dust between the thermal transfer sheet and the image receiving sheet becomes an image defect, which is a serious problem. Approach from outside the device
There was a problem such as material cutting, and it was not enough to manage the material alone, and it was necessary to attach a mechanism to remove dust to the equipment, but we found a material that can maintain a suitable adhesiveness that can clean the transfer material surface, By changing the material of the transport roller, dust was removed without reducing productivity.

The entire system of the present invention will be described in detail below. The present invention realizes a thermal transfer image with sharp halftone dots, and transfers the original paper and records at B2 size or more (515 mm.
X 728 mm or more) is preferable. More preferably, the B2 size is 543 mm × 765 mm, and the system is capable of recording in a larger size (for example, 598 mm × 841 mm or more). One of the performance characteristics of the system of the present invention is that a sharp dot shape can be obtained. The thermal transfer image obtained by this system can be a halftone dot image according to the number of printed lines with a resolution of 2400 dpi or more. Since each halftone dot has almost no bleeding or chipping and its shape is extremely sharp, it is possible to clearly form halftone dots in a high range from highlight to shadow. As a result, it is possible to output high-quality halftone dots with the same resolution as the image setter and CTP setter, and it is possible to reproduce halftone dots and gradation with good print approximation.

The second performance feature of the system of the present invention is that the repeatability is good. Since this thermal transfer image has a sharp halftone dot shape, it can faithfully reproduce halftone dots corresponding to a laser beam. Also, since the recording characteristics have very little dependency on the environmental temperature and humidity, it can be used in a wide range of temperature and humidity. Also, stable repeatability can be obtained. Further, the third performance feature of the system of the present invention is good color reproduction. The thermal transfer image obtained by this system is formed by using the coloring pigment used in the printing ink, and the repeatability is good, so that a highly accurate CMS (color management system) can be realized. Also, this thermal transfer image is a hue such as Japan color, SWOP color, that is,
The hue of the printed matter can be made to substantially match, and the appearance of the color when the light source such as a fluorescent lamp or an incandescent lamp is changed can be changed similarly to the printed matter. The fourth performance feature of the system of the present invention is that the character quality is good. The thermal transfer image obtained by this system has a sharp dot shape, so 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. Since the method of and is a method in which the color material sublimes or scatters, the outline of the halftone dot is blurred. In either method, the melt flows so that a clear contour does not appear. Therefore, based on the thin film transfer technology, in order to solve the new problems in the laser thermal transfer system and to further improve the image quality,
The technology described below was incorporated. The first feature of material technology
Is the sharpening of the dot shape. Image recording is performed by converting laser light into heat in the photothermal conversion layer, transmitting the heat to the adjacent image forming layer, and adhering the image forming layer to the image receiving layer. In order to make the dot shape sharp, the heat generated by the laser light is transmitted to the transfer interface without being diffused in the surface direction, and the image forming layer is sharply broken at the interface between the heated portion and the non-heated portion. Therefore, the photothermal conversion layer in the thermal transfer sheet is made thin and the mechanical properties of the image forming layer are controlled.

Technique 1 for sharpening the dot shape is thinning the photothermal conversion layer. According to the simulation, the photothermal conversion layer is estimated to reach about 700 ° C instantaneously, and if the film is thin, it is easily deformed or destroyed. When deformation / destruction occurs, the photothermal conversion layer transfers to the image receiving sheet together with the image forming layer,
This causes actual damage that the transferred image becomes non-uniform. On the other hand, in order to obtain a predetermined temperature, the photothermal conversion substance must be present in a high concentration in the film, which causes problems such as deposition of dye and migration to an adjacent layer. Conventionally, carbon was often used as the light-heat conversion substance, but in this material, an infrared-absorbing dye, which can be used in a smaller amount than carbon, was used. As the binder, a polyimide compound having sufficient mechanical strength even at a high temperature and having good retention of the infrared absorbing dye was introduced. In this way, by selecting a heat-resistant binder such as an infrared absorbing dye and a polyimide-based material having excellent light-heat conversion characteristics,
It is preferable to make the photothermal conversion layer thinner than about 0.5 μm.

The technique 2 for sharpening the dot shape is to improve the characteristics of the image forming layer. When the photothermal conversion layer is deformed or the image forming layer itself is deformed due to high heat, the image forming layer transferred to the image receiving layer causes unevenness in thickness corresponding to the sub-scanning pattern of the laser light, and thus the image becomes uneven. Apparent transfer density is reduced. 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 dots is impaired and the sensitivity is also lowered. In order to achieve both of these contradictory performances, it is preferable to improve the transfer unevenness by adding a low melting point substance such as wax to the image forming layer. Also, by adding inorganic fine particles instead of the binder, the layer thickness can be appropriately increased so that the image forming layer is sharply broken at the interface between the heated portion and the non-heated portion, and the sharpness and sensitivity of the dots are maintained. Meanwhile, the transfer unevenness can be improved.

Generally, low melting point substances such as wax are
There is a tendency to seep out or crystallize on the surface of the image forming layer,
Problems may occur in the image quality and the temporal stability of the thermal transfer sheet. In order to deal with this problem, it is preferable to use a low melting point substance having a small Sp value difference from the polymer of the image forming layer, which enhances compatibility with the polymer and separates the low melting point substance from the image forming layer. Can be prevented. It is also preferable to mix several kinds of low melting point substances having different structures to cause eutectic and 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 the recording sensitivity depends on temperature and humidity. Generally, when the coating layer of the thermal transfer sheet absorbs moisture, the mechanical properties and thermophysical properties of the layer change, and the humidity dependency of the recording environment occurs. In order to reduce this temperature / humidity dependency, it is preferable that the dye / binder system of the photothermal conversion layer and the binder system of the image forming layer are organic solvent systems. Further, it is preferable to select polyvinyl butyral as the binder of the image receiving layer and to introduce a polymer hydrophobizing technique in order to reduce its water absorption. As a polymer hydrophobizing technique, Japanese Patent Laid-Open No. 8-2
As described in Japanese Patent No. 38858, a hydroxyl group is reacted with a hydrophobic group, or two or more hydroxyl groups are crosslinked with a hardener.

The third characteristic of the material technology is that the print approximation of hue is improved. In addition to the pigment color matching and stable dispersion technology in a thermal head type color proof (eg, FirstProof manufactured by Fuji Photo Film Co., Ltd.), the following problems newly generated in the laser thermal transfer system were solved. That is, the technique 1 for improving the approximation of hue to printed matter is the use of a high heat resistant pigment. Usually, when printing with laser exposure, the image forming layer also receives heat of about 500 ° C or higher, and some of the pigments used in the past were thermally decomposed.
This can be prevented by using a pigment having high heat resistance in the image forming layer. And the technique 2 for improving the approximation of the hue to the printed matter is to prevent the diffusion of the infrared absorbing dye. When the infrared absorbing dye moves from the photothermal conversion layer to the image forming layer due to high heat at the time of printing, in order to prevent the hue from changing, as described above, the infrared absorbing dye / binder having a strong holding power is used. It is preferable to design the photothermal conversion layer in combination. The fourth characteristic of the material technology is high sensitivity. Generally, high-speed printing causes energy shortage, and a gap corresponding to the laser sub-scanning interval is generated. As described above, increasing the dye concentration in the photothermal conversion layer and thinning the photothermal conversion layer / image forming layer can increase the efficiency of heat generation / transfer. Further, for the purpose of improving the adhesiveness with the image receiving layer and the effect of filling the gap by slightly flowing the image forming layer during heating,
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 provide the transferred image with sufficient strength, it is preferable to use, for example, the same polyvinyl butyral as the image forming layer as the binder of the image receiving layer.

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

Technique 1 for improving vacuum adhesion is to make the surface of the thermal transfer sheet uneven. Concavities and convexities were attached to the thermal transfer sheet so that the effect of vacuum adhesion could be sufficiently exerted even when overprinting with two or more colors. As a method for making the thermal transfer sheet uneven, there are generally post-treatments such as embossing and addition of a matting agent to the coating layer, but addition of a matting agent is preferred for simplifying the manufacturing process and stabilizing the material over time. The matting agent needs to be thicker than the coating layer thickness, and when the matting agent is added to the image forming layer, the image in the portion where the matting agent is present may be lost. It is preferably added to the conversion layer, whereby the image forming layer itself has a substantially uniform thickness, and an image free of defects can be obtained on the image receiving sheet.

Next, the features of the systemization technology of the system of the present invention will be described. The first feature of the systemization technology is the configuration of the recording device. In order to reliably reproduce the sharp dots as described above, the recording device side is required to have a highly accurate design. The basic configuration is the same as that of the conventional laser thermal transfer recording device. In this configuration, a recording head equipped with a plurality of high-power lasers irradiates a laser on a thermal transfer sheet and an image receiving sheet fixed on a drum for recording.
This is a so-called heat mode outer drum recording system. Among them, the following aspects are preferable configurations. The configuration 1 of the recording apparatus is to avoid mixing of dust. The image receiving sheet and the thermal transfer sheet are supplied by fully automatic roll supply. Since a large amount of dust is generated from the human body when feeding a small number of sheets, roll feeding 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 sheet is cut into a predetermined length by a cutter during loading and then fixed to a drum. Structure 2 of the recording apparatus is to strengthen the close contact between the image receiving sheet on the recording drum and the thermal transfer sheet. The image receiving sheet and the thermal transfer sheet are fixed to the recording drum by vacuum suction. Vacuum adhesion is used because the mechanical fixing cannot strengthen the adhesion between the image receiving sheet and the thermal transfer sheet. A large number of vacuum suction holes are formed on the recording drum, and the inside of the drum is depressurized by a blower or a depressurizing pump so that the sheet is adsorbed on the drum. Since the thermal transfer sheet is further adsorbed on the image receiving sheet, the size of the thermal transfer sheet is made larger than that of the image receiving sheet. The air between the thermal transfer sheet and the image receiving sheet, which has the largest effect on the recording performance, is sucked from the area outside the image receiving sheet, which is only the thermal transfer sheet.

Structure 3 of the recording apparatus is to stably stack a plurality of sheets on the discharge table. This device shall be able to stack and stack multiple sheets of B2 size or more on a discharge table. When the next sheet B is discharged onto the image-receiving layer of the film A which is already integrated and has thermal adhesiveness, the two may stick to each other. If they stick together, the next sheet will not be ejected properly and jams will occur, which is a problem. The best way to prevent sticking is to prevent contact between films A and B. Several methods are known as contact prevention measures. (a) A method to create a gap between the films by providing a step on the discharge table so that the film shape is not flat, (b)
There are a method of setting the discharge port higher than the discharge table so that the discharge film is dropped from the top, and (c) a method of ejecting air between both films to lift the film discharged later. With this system, the sheet size is
Since B2 is very large, the structure of (a) and (b) becomes very large, so the air ejection method of (c) was adopted. Therefore, a method is adopted in which air is ejected between the two sheets to lift the sheet discharged later.

FIG. 1 shows an example of the configuration of this device. A sequence for forming a full-color image by applying an image forming material to the above apparatus (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, the main-scanning rotation axis of the recording drum 4 and the thermal transfer sheet loading unit (sheet supply unit) 5. 2) The image receiving sheet roll (sheet supplying unit) 6 is unwound by the conveying roller 7, and the leading end of the image receiving sheet is fixed on the recording drum 4 by vacuum suction through a suction hole provided in the recording drum. 3) The squeeze roller 8 comes down onto the recording drum 4, and while the image receiving sheet is being held down, the image receiving sheet is stopped by the rotation of the drum when the image receiving sheet is further conveyed by a prescribed amount, and is cut into a prescribed length by the cutter 9. 4) Further, the recording drum 4 makes one round to complete the loading of the image receiving sheet. 5) Next, in the same sequence as the image receiving sheet, the first-color-black-thermal transfer sheet K is unrolled from the thermal transfer sheet roll 10K, cut, and loaded. 6) Next, the recording drum 4 starts to rotate at a high speed, the recording head 2 on the sub-scanning rail 3 starts to move, and when the recording start position is reached, the recording head 2 irradiates the recording laser on the recording drum 4 according to the recording image signal. To be done. The irradiation is terminated at the recording end position, and the sub-scanning rail operation and the drum rotation are stopped. Return the recording head on the sub-scanning rail to the origin. 7) Only the thermal transfer sheet K is peeled off while leaving the image receiving sheet on the recording drum. Therefore, the tip of the thermal transfer sheet K is hooked with a claw, pulled out in the discharge direction, and discarded from the waste port 32 to the waste box 35. 8) Repeat 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 transferred from the thermal transfer sheet roll 10C, the third color-magenta thermal transfer sheet M is transferred from the thermal transfer sheet roll 10M, and the fourth color-yellow thermal transfer sheet Y is sequentially transferred from the thermal transfer sheet roll 10Y. Be paid out. This is the reverse of the general printing order, but this is because the color order on the real paper is reversed by the real paper transfer in a later step. 9) When the four colors are completed, the recorded image receiving sheet is finally discharged to the discharge tray 31. The method of peeling from the drum is the same as that of the thermal transfer sheet of 7), but since it is not discarded unlike the thermal transfer sheet, it is returned to the discharge table by switchback when it reaches the disposal port 32. When discharged to the discharge table, air 34 is jetted from below the discharge port 33 to enable stacking of a plurality of sheets. In the sheet conveying unit from the sheet supplying unit to the discharge table 31 and the discarding port 32, the respective sheets are fully automatically conveyed inside the recording apparatus 1 without human intervention.

Conveying roller 7 at either the supplying portion or the conveying portion of the thermal transfer sheet roll and the image receiving sheet roll.
In addition, it is preferable to use an adhesive roller having an adhesive material on the surface.

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

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

The adhesive roller can clean the surface 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 second feature 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 in order to perform the process of transferring to the printing actual paper (called “the actual paper”). This process is First Proof
Exactly the same as ^TM . When the image receiving sheet and the main paper are overlapped and heat and pressure are applied, the two adhere to each other, and then when the image receiving film is peeled off from the main paper, only the image and the adhesive layer remain on the main paper,
The image receiving sheet support and the cushion layer are peeled off. Therefore, in practice, the image is transferred from the image receiving sheet to the actual paper.

In First Proof ^™ , the transfer is performed by stacking the main paper and the image receiving sheet on a guide plate made of aluminum and passing it between heat rollers. The reason why the aluminum guide plate is used is to prevent the deformation of the paper. However, if this is adopted for the B2 size system, an aluminum guide plate larger than the B2 is required, which causes a problem that the installation space of the device becomes large. Therefore, in this system, the aluminum guide plate was not used, and the structure was adopted in which the transport path was rotated 180 degrees and discharged to the insertion side, so the installation space was extremely compact (Fig. 2). However, since the aluminum guide plate is not used, the problem that the main paper is deformed occurs.
Specifically, the discharged pair of the real paper and the image receiving sheet curls with the image receiving sheet inside and rolls on the discharge table. It is very difficult as a work to peel off the image receiving sheet from the rolled up paper.

Then, considering a method of preventing curling, there are a bimetal effect due to the difference in shrinkage amount between the main paper and the image receiving sheet, and an iron effect due to the structure wound around the heat roller. When the image receiving sheet is inserted over the main paper as in the past, the thermal contraction of the image receiving sheet in the insertion direction is larger than the thermal contraction of the main paper. , The direction of ironing effect is the same, so the curl becomes awful due to the synergistic effect. However, if the image receiving sheet is inserted so as to be on the lower side of the paper, the curl of the bimetal effect will face downwards and the curl of the iron effect will face upwards, and the curls will be offset and there will be no problem.

The sequence of main paper transfer is as follows (hereinafter referred to as the main paper transfer method used in this system). The thermal transfer device 41 shown in FIG. 2 used in this method is a manual device unlike a recording device. 1) First, depending on the type of the main paper 42, the heat roller 43
The temperature (100 to 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 by a static elimination brush (not shown). The dust-removed main paper 42 is placed on top of it. At this time, since the size of the main paper 42 placed above the image receiving film 20 placed below is larger, the position of the image receiving sheet 20 becomes invisible and alignment is difficult to perform. In order to improve the workability, marks 45 indicating the placement positions of the image receiving sheet and the main sheet are provided on the insertion table 44. The reason why the main paper is larger is to prevent the image receiving sheet 20 from slipping off from the main paper 42 and contaminating the heat roller 43 with the image receiving layer of the image receiving sheet 20. 3) When the image receiving sheet and the main sheet are stacked and pushed into the insertion port, the insertion roller 46 is rotated and both of them are heated by the heat roller 43.
Send towards. 4) When the leading edge of the paper reaches the position of the heat roller 43, the heat roller is nipped and the transfer is started. The heat roller is a heat-resistant silicone rubber roller. Here, the image receiving sheet and the main paper are adhered to each other by applying pressure and heat at the same time. A guide 47 made of a heat-resistant sheet is installed downstream of the heat roller, and the image receiving sheet / main paper pair is conveyed upward while being heated between the upper heat roller and the guide 47, and at the position of the peeling claw 48. 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 / main paper pair coming out from the discharge port 50 is discharged onto the insertion table while being adhered. After that, the image receiving sheet 20 is manually peeled off from the paper 42.

The second feature of the systematization technique is the system configuration. By connecting the above apparatus to the plate making system, the function as a color proof can be exhibited. As a system, it is necessary for a proof to output a printed matter with an image quality as close as possible to a printed matter output from certain plate-making data. Therefore, software is needed to bring colors and halftone dots closer to the printed matter. A specific connection example is introduced.

When proofing a printed matter from a plate making system called Celebra ^™ manufactured by Fuji Photo Film Co., Ltd., the system connection is as follows. Celebra to CTP (Comp
uterTo Plate) system. A final printed matter is obtained by applying the printing plate thus output to a printing machine. As a color proof to Celebra the recording device Fuji Photo Film Co., Ltd. Luxel FINALPROOF 5600 (hereinafter,
(Also referred to as FINALPROOF), but in the meantime a Fuji Photo Film PD system ^TM is connected as proof drive software to bring colors and dots closer to the printed matter. The contone (continuous tone) data converted to raster data by Celebra is converted to binary data for halftone dots.
It is output to the CTP system and finally printed. On the other hand, the same contone data is also output to the PD system. The PD system converts the received data by a four-dimensional (black, cyan, magenta, yellow) table so as to match the color of the printed matter. Finally, it is converted to binary data for halftone dots so that it matches the halftone dots of the printed matter, and FINA
Output to LPROOF (Fig. 3). The four-dimensional table is experimentally created in advance and stored in the system. The experiment for making is as follows. Prepare an image in which important color data is printed via the CTP system and an image output to FINAL PROOF via the PD system, compare the colorimetric values, and create a table to minimize the difference.

As described above, according to the present invention, a system configuration capable of sufficiently exerting the ability of a material having high resolution can be 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 surface layer thereof is 3.0 or less, and the surface roughness Rz of the image receiving layer surface of the image receiving sheet and its back surface layer The absolute value of the difference in surface roughness Rz is preferably 3.0 or less. With such a configuration, image defects can be prevented in cooperation with the above-mentioned cleaning means, a conveyance jam can be eliminated, and dot gain stability can be further improved.

In the present specification, the surface roughness Rz means JIS.
Rz (maximum height) is the average surface roughness of 10 points, and the average surface of the portion extracted from the curved surface of the roughness by the reference area is the reference surface Is the input value of the distance between the average value of and the average value of the depth of the valley bottom from the deepest to the fifth. A stylus type three-dimensional roughness meter (Surfcom 570A-3DF) manufactured by Tokyo Seimitsu Co., Ltd. is used for the measurement. The measurement direction is vertical and the cutoff value is 0.08 mm.
The measuring area is 0.6 mm × 0.4 mm, the feed pitch is 0.005 mm, and the measuring 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 and the surface roughness Rz of the surface of the back layer of the thermal transfer sheet is
It is 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 back surface of the image receiving layer is 1.0.
The following is preferable from the viewpoint of further improving the above effects.

Further, as another embodiment, the surface roughness of the surface of the image forming layer and the surface of the back surface of the thermal transfer sheet 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, the image defect can be prevented in cooperation with the above-mentioned cleaning means, the conveyance jam can be eliminated, and the 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 largely depends on the smoothness of the surface of the image forming layer, and can affect the uniformity of the thickness of the image forming layer. Higher gloss is more uniform as an image forming layer and is more suitable for use in high-definition images. However, if smoothness is high, resistance during transportation becomes larger, and both are in a trade-off relationship.
When the glossiness is in the range of 80 to 99, both can be compatible and balanced.

The Vickers hardness Hv of the sticky material used for the sticky roller is 50 kg / mm ² (≈490 MPa) or less so that dust as a foreign substance can be sufficiently removed and image defects can be suppressed. Is preferred.

Vickers hardness means that the facing angle is 13
The hardness is a hardness measured by applying a static load to a 6-degree regular pyramid-shaped diamond indenter, and the Vickers hardness Hv is obtained by the following formula.

Hardness Hv = 1.854 P / d ² (kg / mm ² ) ≈1
8.1692P / d ² (MPa) where P: Load magnitude (Kg), d: Diagonal square diagonal length (mm)

Further, in the present invention, the elastic material at 20 ° C. of the adhesive material used for the above-mentioned adhesive roller has
It is preferably 200 kg / cm ² (≈19.6 MPa) or less, since dust as a foreign substance can be sufficiently removed and image defects can be suppressed as in the above case.

Next, the outline of the mechanism of multicolor image formation by thin film thermal transfer using a laser will be described with reference to FIG. An image forming laminate 30 is prepared 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. . The thermal transfer sheet 10 is the support 1
2 and on it, the photothermal conversion layer 14, and further on it,
The image receiving sheet 20 has an image forming layer 16 and a support 22.
Then, the image receiving layer 24 is provided 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 therewith (FIG. 4A). When the laser beam is imagewise radiated from the side of the support 12 of the thermal transfer sheet 10 of the laminated body 30, the laser light irradiation region of the photothermal conversion layer 14 of the thermal transfer sheet 10 generates heat and the image forming layer 16 is formed.
The adhesive force with is reduced (FIG. 4 (b)). After that, when the image receiving sheet 20 and the thermal transfer sheet 10 are peeled off, the laser light irradiation region 16 ′ of the image forming layer 16 becomes the image receiving sheet 2.
0 is transferred onto the image receiving layer 24 (FIG. 4C).

In forming a multicolor image, the laser light used for light irradiation is preferably multi-beam light, and particularly preferably multi-beam two-dimensional array. The multi-beam two-dimensional array uses a plurality of laser beams when recording by laser irradiation, and the spot arrays of these laser beams have a plurality of rows along the main scanning direction and a plurality of spots along the sub scanning direction. It means a two-dimensional plane array consisting of rows. By using a laser beam having a multi-beam two-dimensional array, the time required for laser recording can be shortened.

The laser light used can be used without particular limitation, and gas laser light such as argon ion laser light, helium neon laser light and helium cadmium laser light, solid laser light such as YAG laser light and semiconductor laser light can be used. Direct laser light such as dye laser light, excimer laser light, or the like is used. Alternatively, light obtained by converting these laser lights into a half wavelength through a second harmonic element can also be used. In the multicolor image forming method, considering output power and ease of modulation,
It is preferable to use semiconductor laser light. In the multicolor image forming method, it is preferable to irradiate the laser light under the condition that the beam diameter on the photothermal 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 (particularly 3 m / sec or more) is preferable.

In multicolor image formation, the layer thickness of the image forming layer on the black thermal transfer sheet is larger than the layer thickness of the image forming layer on 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, when the black thermal transfer sheet is irradiated with a laser, it is possible to suppress a decrease in density due to uneven transfer. By setting the thickness of the image forming layer in the black thermal transfer sheet to 0.5 μm or more, the image density is maintained without transfer unevenness when recording with high energy, and the image density required as a proof for printing is achieved. can do. Since this tendency becomes more remarkable under high humidity conditions, it is possible to suppress changes in concentration due to the environment. On the other hand, when the layer thickness is 0.7 μm or less, the transfer sensitivity can be maintained during laser recording, and small dots and fine lines can be improved. This tendency is more remarkable under low humidity conditions. Also, 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 layer thickness of the image forming layer in the black thermal transfer sheet is 0.5 to 0.7 μm, and the layer thickness of the image forming layer in each of the yellow, magenta and cyan thermal transfer sheets is 0. 0.2 μm or more and 0.5 μm
It is preferably less than. The yellow, magenta,
By setting the layer thickness of the image forming layer in each of the thermal transfer sheets of cyan and cyan to 0.2 μm or more, it is possible to maintain the density without transfer unevenness during laser recording. 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 kinds of carbon blacks having different coloring powers. P / B (Pigment / Binder) ) It is preferable because the reflection density can be adjusted while keeping the ratio within a certain range. The coloring power of carbon black can be represented by various methods. For example, PVC described in JP-A-10-140033 is used.
Examples include blackness. The PVC blackness means that carbon black is added to PVC resin, dispersed by two rolls and made into a sheet, and carbon black “# 40” of Mitsubishi Chemical Corporation,
The blackness of "# 45" is set to 1 point and 10 points, respectively, and a reference value,
The blackness of the sample is evaluated by visual judgment. PV
Two or more kinds of carbon blacks having different C blacknesses can be appropriately selected and used according to the purpose.

Hereinafter, a specific method for preparing a sample will be described. <Sample preparation method> 40% by mass of sample carbon black was blended with LDPE (low density polyethylene) resin in a 250 cc Banbury mixer, and kneading was performed 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, it is diluted at 120 ° C. by a two-roll mill so that the carbon black concentration becomes 1% by mass.

Diluted compound preparation conditions LDPE resin 58.3 g Calcium stearate 0.2 g Carbon black 40% by mass blended resin 1.5 g Slit width 0.3 mm is made into a sheet, and this sheet is cut into chips and placed on a hot plate at 240 ° C. 65 ± 3 μm
To form a film.

As a method of forming a multicolor image, as described above, the thermal transfer sheet is used, and a large number of image layers (image forming layers on which images are formed) are repeatedly superposed on the same image receiving sheet. A color image may be formed, or a multicolor image may be formed by once forming an image on the image receiving layers of a plurality of image receiving sheets and then retransferring the image onto a 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 in which this is combined with an image receiving sheet is independently four kinds (four colors, four colors, (Cyan, magenta, yellow, black) manufactured. To each laminate, for example, through a color separation filter, laser light irradiation according to a digital signal based on the image is performed, and subsequently, the thermal transfer sheet and the image receiving sheet are peeled off, and a color separation image of each color is formed on each image receiving sheet. Are formed independently. Next, each color separation image formed is
A multicolor image can be formed by sequentially laminating a separately prepared actual support such as printing paper or a support similar thereto.

The thermal transfer sheet using laser light irradiation is
It is preferable to form an image on the image receiving sheet by converting the laser beam into heat and utilizing the thermal energy to form an image forming layer containing a pigment on the image receiving sheet by a thin film transfer method. The technique used for developing the image forming material composed of a sheet 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 may also include the imaging materials used in these systems.

The thermal transfer sheet and the image receiving sheet will be described in detail below. [Thermal Transfer Sheet] The thermal transfer sheet has at least a photothermal 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 is preferably rigid, has good dimensional stability, and can withstand heat during image formation. Preferred examples of the support material include polyethylene terephthalate, polyethylene-2,6-naphthalate, polycarbonate, polymethylmethacrylate, polyethylene,
Polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, styrene-acrylonitrile copolymer, polyamide (aromatic or aliphatic), polyimide,
Examples thereof include synthetic resin materials such as polyamide imide and polysulfone. Of these, biaxially oriented polyethylene terephthalate is preferable in consideration of mechanical strength and dimensional stability against heat. When used in the production of a color proof utilizing laser recording, the support of the thermal transfer sheet is preferably made of a transparent synthetic resin material that transmits laser light. The thickness of the support is 25 to 130 μm
Is preferable, and 50 to 120 μm is particularly preferable. The center line average surface roughness Ra (measured according to JIS B0601 using a surface roughness measuring instrument (Surfcom, manufactured by Tokyo Seiki Co., Ltd.)) of the support on the image forming layer side may be less than 0.1 μm. preferable. Young's modulus in the longitudinal direction of the support 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 GP
It is preferably a). 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 width direction of the support is preferably 3
˜30 kg / mm ² (≈29.4 to 294 MPa), and the F-5 value in the longitudinal direction of the support is F-5 in the transverse direction of the support.
It is generally higher than the value, but not particularly when it is necessary to increase the strength in the width direction. The heat shrinkage ratio of the support in the longitudinal and width directions at 100 ° C. for 30 minutes is preferably 3% or less, more preferably 1.5% or less, and the heat shrinkage ratio at 80 ° C. for 30 minutes is preferably 1%. Less than,
More preferably, it is 0.5% or less. Breaking strength is 5 to 100 kg / mm ^{2 in} both directions (≈49 to 980 MP
a), the elastic modulus is 100 to 2000 kg / mm ² (≈0.
98 to 19.6 GPa) is preferable.

The support of the thermal transfer sheet is subjected to surface activation treatment and / or attachment of one or two or more undercoat layers in order to improve the adhesion to the photothermal conversion layer provided thereon. Good. Examples of the surface activation treatment include glow discharge treatment and corona discharge treatment. It is preferable that the material of the undercoat layer has high adhesiveness to both surfaces of the support and the photothermal conversion layer, has low thermal conductivity, and has excellent heat resistance. Examples of the material of such an undercoat layer include styrene, styrene-butadiene copolymer, gelatin and the like. The total thickness of the undercoat layer is usually 0.01 to 2 μm. If necessary, various kinds of functional layers such as an antireflection layer and an antistatic layer may be attached to the surface of the thermal transfer sheet opposite to the side where the photothermal conversion layer is attached, or surface treatment may be performed.

(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 where the light-heat conversion layer is provided. The back layer is preferably composed of two layers, a first back layer adjacent to the support and a second back layer provided on the opposite side of the first back layer from the support. In the present invention, the ratio B / A of the mass A of the antistatic agent contained in the first back layer and the mass B of the antistatic agent contained in the second back layer is preferably less than 0.3.
When B / A is 0.3 or more, the slipperiness and the powder drop of the back layer tend to be deteriorated.

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

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

Further, the conductive fine particles are used as an antistatic agent.
You can also As such conductive fine particles,
For example, ZnO, TiO₂ , SnO₂ , Al₂O₃ , I
n₂O ₃ , MgO, BaO, CoO, CuO, Cu₂O,
CaO, SrO, BaO₂, PbO, PbO₂ , MnO₃
 , MoO₃ , SiO₂ , ZrO₂ , Ag₂O, Y₂O₃,
Bi₂O₃, Ti₂O₃, Sb₂O₃, Sb₂O_Five, K₂Ti
₆O₁₃, NaCaP₂O ₁₈, MgB₂O_FiveOxides such as Cu
Sulfides such as S and ZnS; SiC, TiC, ZrC, V
Carbides such as C, NbC, MoC, WC; Si₃N_Four , T
iN, ZrN, VN, NbN, Cr₂N and other nitrides; T
iB₂ , ZrB₂, NbB₂ , TaB₂ , CrB, Mo
B, WB, LaB_Five Boride; TiSi₂ , ZrSi
₂ , NbSi ₂ , TaSi₂ , CrSi₂ , MoSi
₂ , WSi₂ And other silicides; BaCO₃ , CaCO₃ , S
rCO₃ , BaSO_Four , CaSO_Four Metal salts such as SiN
_Four -SiC, 9Al₂O₃ -2B₂O₃ Complex such as
These may be used alone or in combination of two or more.
Yes. Of these, SnO₂ , ZnO, Al₂O₃ , T
iO₂ , In₂O₃ , MgO, BaO and MoO₃Is preferred
Well, SnO₂ , ZnO, In₂O₃And TiO₂ Garasara
Preferred, SnO₂ Is particularly preferable.

When the thermal transfer material of the present invention is used in a laser thermal transfer recording system, the antistatic agent used in the back layer is preferably substantially transparent so that the laser beam can pass therethrough.

When a conductive metal oxide is used as an antistatic agent, its particle size is preferably as small as possible in order to minimize light scattering, but the ratio of the refractive index of the particles to the binder is used as a parameter. It should 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 0.003 to 0.2 μm. Here, the average particle diameter is a value that includes not only the primary particle diameter of the conductive metal oxide but also the particle diameter of the higher-order structure.

In addition to the antistatic agent, various additives and binders such as a surfactant, a slip agent and a matting agent can be added to the first and second back layers. The amount of the antistatic agent contained in the first back layer is preferably 10 to 1000 parts by mass, and 200 to 80 parts by mass with respect to 100 parts by mass of the binder.
0 mass part is more preferable. Further, the amount of the antistatic agent contained in the second back layer is preferably 0 to 300 parts by mass, more preferably 0 to 100 parts by mass with respect to 100 parts by mass of the binder.

As the binder used for forming the first and second back layers, for example, homopolymers and copolymers of acrylic acid type monomers such as acrylic acid, methacrylic acid, acrylic acid ester, and methacrylic acid ester. , Nitrocellulose, methyl cellulose, ethyl cellulose,
Cellulosic polymers such as cellulose acetate,
Polyethylene, polypropylene, polystyrene, vinyl chloride copolymers, vinyl chloride-vinyl acetate copolymers, polyvinylpyrrolidone, polyvinyl butyral, copolymers of vinyl compounds and vinyl compounds such as polyvinyl alcohol, polyesters, polyurethanes, polyamides Examples thereof include condensation-type polymers, rubber-based thermoplastic polymers such as butadiene-styrene copolymer, polymers obtained by polymerizing and crosslinking photopolymerizable or thermopolymerizable compounds such as epoxy compounds, and melamine compounds. .

(Light-to-heat conversion layer) The light-to-heat conversion layer contains a light-to-heat conversion substance, a binder, and optionally a matting agent,
Further, other components are contained if necessary. The photothermal conversion substance is a substance having a function of converting irradiated light energy into heat energy. Generally, it is a dye (including a pigment; the same applies hereinafter) capable of absorbing laser light. When an image is recorded with an infrared laser, an infrared absorbing dye is preferably used as the photothermal conversion substance. Examples of the dyes include black pigments such as carbon black, pigments of macrocyclic compounds having absorption in the visible to near infrared region such as phthalocyanine and 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, phthalocyanine dyes), and organometallic compound dyes such as dithiol nickel complexes. Among them, the cyanine dye exhibits a high extinction coefficient with respect to light in the infrared region. Therefore, when it is used as a photothermal conversion substance, the photothermal conversion layer can be thinned, and as a result, the recording sensitivity of the thermal transfer sheet can be improved. It is preferable because it can be further improved. As the photothermal conversion substance, an inorganic material such as a particulate metal material such as blackened silver can be used in addition to the dye.

The binder contained in the photothermal conversion layer has at least the strength to form a layer on the support,
Resins with high thermal conductivity are preferred. Furthermore, when the resin is a heat-resistant resin that does not decompose even by the heat generated from the photothermal conversion substance during image recording, the smoothness of the surface of the photothermal conversion layer after light irradiation is achieved even when high-energy light irradiation is performed. Is preferable because it can be maintained. Specifically, the thermal decomposition temperature (T
A resin having a temperature increase rate of 10 ° C./min by the GA method (temperature at which 5% mass is reduced in an air stream) of 400 ° C. or higher is preferable, and a resin having a thermal decomposition temperature of 500 ° C. or higher is preferable. More preferable. Further, 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. If the glass transition temperature is lower than 200 ° C., fog may occur in the formed image, and if it is higher than 400 ° C., the solubility of the resin may be lowered and the production efficiency may be lowered.
The heat resistance of the binder of the photothermal conversion layer (for example, thermal deformation temperature or thermal decomposition temperature) is preferably higher than that of the material used for the other layers provided on the photothermal conversion layer.

Specifically, acrylic acid resins such as polymethylmethacrylate, polycarbonate, polystyrene,
Vinyl chloride / vinyl acetate copolymer, vinyl resin such as polyvinyl alcohol, polyvinyl butyral, polyester, polyvinyl chloride, polyamide, polyimide, polyetherimide, polysulfone, polyether sulfone, aramid, polyurethane, epoxy resin, urea / melamine Resin etc. are mentioned. Among these, the polyimide resin is preferable.

Particularly, the polyimide resins represented by the following general formulas (I) to (VII) are soluble in an organic solvent, and 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 stability and moisture resistance of the coating solution for the light-heat conversion layer are improved.

[0077]

[Chemical 1]

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

[0079]

[Chemical 2]

[0080]

[Chemical 3]

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.

[0082]

[Chemical 4]

[0083]

[Chemical 5]

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

As a standard for determining whether or not the resin is soluble in an organic solvent, 10 parts by mass or more of the resin is dissolved at 25 ° C. 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 photothermal conversion layer. More preferably, the resin is 100 parts by mass or more with respect to 100 parts by mass of N-methylpyrrolidone.

Examples of the matting agent contained in the photothermal conversion layer include inorganic fine particles and organic fine particles. 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 white, Lead white, Sieglite, quartz, diatomaceous earth, barlite, bentonite, mica, synthetic mica, etc. may be mentioned. As the organic fine particles, fluororesin particles,
Examples thereof include resin particles such as guanamine resin particles, acrylic resin particles, styrene-acrylic 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 .

If necessary, a surfactant, a thickener, an antistatic agent and the like may be added to the photothermal conversion layer.

The light-heat conversion layer is prepared by dissolving a light-heat conversion substance and a binder, and adding a matting agent and other components to the solution, if necessary, to prepare a coating solution, which is coated on a support and dried. It can be provided. Examples of the organic solvent for dissolving the polyimide resin include 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, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, γ
-Butyrolactone, ethanol, methanol and the like. The coating and drying can be carried out by using ordinary coating and drying methods. Drying is usually performed at a temperature of 300 ° C. or lower, and preferably at a temperature of 200 ° C. or lower. When polyethylene terephthalate is used as the support, it is preferably dried at a temperature of 80 to 150 ° C.

When the amount of the binder in the light-heat conversion layer is too small, the cohesive force of the light-heat conversion layer is lowered, and when the formed image is transferred to the image-receiving sheet, the light-heat conversion layer is easily transferred together with the image-forming sheet, and the image formation of the image becomes difficult. This will cause color mixing. On the other hand, when the amount of the polyimide resin is too large, the layer thickness of the photothermal conversion layer is increased in order to achieve a constant light absorption rate, and the sensitivity is likely to be lowered. The solid content mass ratio of the photothermal conversion substance and the binder in the photothermal conversion layer is preferably 1:20 to 2: 1, and more preferably 1:10 to 2: 1.
Further, it is preferable to make the light-heat conversion layer thin, because the heat transfer sheet can have high sensitivity as described above. The photothermal conversion layer preferably has a thickness of 0.03 to 1.0 μm, and preferably 0.0 to 1.0 μm.
More preferably, it is 5 to 0.5 μm. Further, the light-heat conversion layer is 0.80 to 1.
The optical density of 26 is preferable because the transfer sensitivity of the image forming layer is improved.
It is more preferable to have an optical density of 2 to 1.15.
When the optical density at the laser peak wavelength is less than 0.80, it becomes insufficient to convert the irradiated light into heat and the transfer sensitivity may decrease. On the other hand, when it exceeds 1.26, the function of the photothermal conversion layer is affected during recording, and fogging may occur.

(Image Forming Layer) The image forming layer contains at least a pigment for forming an image by being transferred onto an image receiving sheet, and further contains a binder for forming a layer and, if desired, other components. To do. Pigments are generally roughly classified into organic pigments and inorganic pigments, the former having particularly excellent transparency of the coating film, and the latter generally having properties such as excellent hiding properties, so that they can be appropriately selected depending on the application. Good. When the thermal transfer sheet is used for printing color proofing, an organic pigment that has a color tone that matches or is close to yellow, magenta, cyan, and black generally used for printing ink is preferably used. In addition, metal powder, fluorescent pigment, etc. may also be used. Examples of suitable 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 according to hues, but the pigments are not limited to these.

1) Yellow Pigment Pigment Yellow (Pigment Yellow)
12 (C.I. No. 21090) Example) Permanent Yellow (Permanent Yellow) DHG (Clariant Japan KK)
Manufactured by Toyo Ink Mfg. Co., Ltd., Irg
alite Yellow (Irgarite yellow)
LCT (Ciba Specialty Chemicals Co., Ltd.)
), SYMLER FAST YELLOW (Shimla Fast Yellow) GTF 219 (Dainippon Ink and Chemicals, Inc.) Pigment Yellow (Pigment Yellow)
13 (CI. No. 21100) Example) Permanent Yellow (Permanent Yellow) GR (manufactured by Clariant Japan Co., Ltd.),
Lionol Yellow (Rionol Yellow)
1313 (manufactured by Toyo Ink Mfg. Co., Ltd.) Pigment Yellow (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
2270 (manufactured by Dainichiseika Kogyo Co., Ltd.), Symler
Fast Yellow (Shimla First Yellow) 4400 (manufactured by Dainippon Ink and Chemicals, Inc.) Pigment Yellow (Pigment Yellow)
17 (C.I. No. 21105) Example) Permanent Yellow (Permanent Yellow) GG02 (Clariant Japan KK)
Manufactured by SYMLER FAST Yellow (Shimla First Yellow) 8GF (manufactured by Dainippon Ink and Chemicals, Inc.) Pigment Yellow
155 Example) Graphtol Yellow (Graph Thor Yellow) 3GP (Clariant Japan KK) Pigment Yellow (Pigment Yellow)
180 (CI No. 21290) Example) Novoperm Yellow (Novopalm Yellow) P-HG (manufactured by Clariant Japan KK),
PV Fast Yellow (First Yellow)
HG (Clariant Japan KK) Pigment Yellow (Pigment Yellow)
139 (C.I.No. 56298) Example) Novoperm Yellow (Novopalm Yellow) M2R 70 (Clariant Japan KK)
Made)

2) Magenta Pigment Pigment Red 57:
1 (C.I.No. 15850: 1) Example) Graphtol Rubin (Graphtor Rubin) L6B (manufactured by Clariant Japan KK), L
ionol Red 6B-42
90G (Toyo Ink Mfg. Co., Ltd.), Irgalite
Rubine (Irgarite 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) Hosterm Pink (Hoster Palm Pink) E (manufactured by Clariant Japan KK), Li
onogen Magenta (Rionogen Magenta)
5790 (manufactured by Toyo Ink Mfg. Co., Ltd.), Fastog
en Super Magenta RH (Dainippon Ink and Chemicals, Inc.)
Made) Pigment Red (Pigment Red) 53:
1 (CI. No. 15585: 1) Example) Permanent Lake Red (Permanent Lake Red) LCY (Clariant Japan Co., Ltd.), SYMLER LAKE RED (Shimla Lake Red) C conc (Dainippon Ink and Chemicals, Inc.) )) Pigment Red 48:
1 (C.I.No. 15865: 1) Example) Lionol Red (Lionol Red) 2B
3300 (manufactured by Toyo Ink Mfg. Co., Ltd.), Symule
r Red (Shimla Red) NRY (manufactured by Dainippon Ink and Chemicals, Inc.) Pigment Red (Pigment Red) 48:
2 (C.I.No. 15865: 2) Example) Permanent Red (Permanent Red) W2T (manufactured by Clariant Japan KK), Li
onol Red (Rionol Red) LX235
(Manufactured by Toyo Ink Mfg. Co., Ltd.), Symboler Red
(Shimla Red) 3012 (manufactured by Dainippon Ink and Chemicals, Inc.) Pigment Red 48:
3 (C.I.No. 15865: 3) Example) Permanent Red (Permanent Red) 3RL (Clariant Japan KK), Sy
muller Red 2BS (manufactured by Dainippon Ink and Chemicals, Inc.) Pigment Red 177
(C.I. No. 65300) Example) Cromophthal Red (Chromophtal red) A2B (manufactured by Ciba Specialty Chemicals Co., Ltd.)

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

4) Black Pigment Pigment Black (Pigment Black)
7 (Carbon black CI No. 77266) Example) Mitsubishi carbon black MA100 (manufactured by Mitsubishi Chemical Co., Ltd.), Mitsubishi carbon black # 5 (manufactured by Mitsubishi Chemical Co., Ltd.), Black Pearls (Black Pearls) 430 (Cabot) Co. (Cabot)
Further, as a pigment that can be used in the present invention, "Pigment Handbook, edited by Japan Pigment Technology Association, Seibundo Shinkosha, 198"
9 ”,“ COLOUR INDEX, THE SOCIETY OF
DYES & COLOURIST, THIRD EDITION, 1987 "
It is possible to select an appropriate product by referring to the above.

The average particle size of the pigment is 0.03 to
1 μm is preferable, and 0.05 to 0.5 μm is more preferable. When the particle size is 0.03 μm or more, the dispersion cost does not increase, and the dispersion does not gel,
On the other hand, when it 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.

As the binder for the image forming layer, an amorphous organic high molecular polymer having a softening point of 40 to 150 ° C. is preferable. Examples of the amorphous organic polymer include butyral resin, polyamide resin, polyethyleneimine resin, sulfonamide resin, polyester polyol resin, petroleum resin, styrene, vinyltoluene, α-methylstyrene, 2-methylstyrene, Chlorostyrene, vinyl benzoic acid, sodium vinyl benzene sulfonate, styrene and its derivatives such as aminostyrene, substituted homopolymers and copolymers, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate and other methacrylic acid esters. And acrylic acid esters such as methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate and α-ethylhexyl acrylate, and dienes such as acrylic acid, butadiene and isoprene, and acene. Use of vinyl monomers such as lilonitrile, vinyl ethers, maleic acid and maleic acid esters, maleic anhydride, cinnamic acid, vinyl chloride and vinyl acetate, or a copolymer with other monomers. You can Two or more kinds of these resins may be mixed and used.

The image forming layer preferably contains the pigment in an amount of 30 to 70% by mass, more preferably 30 to 50% by mass. The image forming layer is made of resin 70
It is preferably contained in an amount of 30 to 30% by mass, more preferably 70 to 40% by mass.

The image forming layer may contain the following components (1) to (3) as the other components. Waxes Examples of waxes include mineral waxes, natural waxes, and synthetic waxes. Examples of the mineral waxes include petroleum wax such as paraffin wax, microcrystalline wax, ester wax, and oxidized wax, montan wax, ozokerite, ceresin, and the like. Of these, paraffin wax is preferable. The paraffin wax is separated from petroleum and various types are commercially available depending on the melting point thereof. Examples of the natural waxes include plant waxes such as carnauba wax, wood wax, auricurie wax, and espal wax, and animal waxes such as dense wax, insect wax, shellac wax, and whale wax.

The above synthetic wax is generally used as a lubricant and is usually composed of a higher fatty acid compound. Examples of such synthetic waxes include the following. 1) Fatty acid wax A 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 and azelaic acid.
In addition, metal salts of the above fatty acids (for example, K, Ca, Z
n, Mg, etc.). 2) Fatty Acid Ester Wax Specific examples of the fatty acid ester include ethyl stearate, lauryl stearate, ethyl behenate, hexyl behenate, and behenyl myristate. 3) Fatty Acid Amide Wax Specific examples of the fatty acid amide include stearic acid amide and lauric acid amide. 4) a linear saturated aliphatic alcohols represented by an aliphatic alcohol wax represented by the following general formula: CH ₃ (CH _{2) n} OH wherein formula, n represents an integer of 6 to 28. Specific examples include stearyl alcohol and the like.

Among the above synthetic waxes 1) to 4), higher fatty acid amides such as stearic acid amide and lauric acid amide are particularly preferable. The wax compounds may be used alone or in combination as required.

Plasticizer As the plasticizer, an ester compound is preferable, and dibutyl phthalate, di-n-octyl phthalate, di (2-ethylhexyl) phthalate, dinonyl phthalate, dilauryl phthalate, butyl lauryl phthalate, Phthalates such as butylbenzyl phthalate, adipic acid di (2-
Aliphatic dibasic acid esters such as ethylhexyl) and di (2-ethylhexyl) sebacate, tricresyl phosphate, phosphoric acid triesters such as tri (2-ethylhexyl) phosphate, polyol polyesters such as polyethylene glycol ester, epoxy Known plasticizers such as epoxy compounds such as fatty acid esters can be used. Among these, esters of vinyl monomers, particularly esters of acrylic acid or methacrylic acid, are preferable because they have a large effect of improving transfer sensitivity and transfer unevenness, and a large effect of controlling elongation at break.

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

The plasticizer may be a polymer, and among them, polyester is preferable because it has a large effect of addition and is difficult to diffuse under storage conditions. Examples of the polyester include sebacic acid type polyester and adipic acid type polyester. The additives contained in the image forming layer are not limited to these. The plasticizers may be used alone or in combination of two or more.

If the content of the above-mentioned additive in the image forming layer is too large, the resolution of the transferred image is lowered, the film strength of the image forming layer itself is lowered, and the adhesion between the photothermal conversion layer and the image forming layer is decreased. The transfer of the unexposed portion to the image receiving sheet may occur due to the decrease in the force. From the above viewpoint, the content of the waxes is preferably 0.1 to 30% by mass, and more preferably 1 to 20% by mass of the total solid content in the image forming layer. Further, the content of the plasticizer is preferably 0.1 to 20% by mass, and more preferably 0.1 to 10% by mass of the total solid content in the image forming layer.

Others In addition to the above components, the image-forming layer further contains a surfactant,
Inorganic or organic fine particles (metal powder, silica gel, etc.), oils (linseed oil, mineral oil, etc.), thickeners, antistatic agents, etc. may be contained. The energy required for transfer can be reduced by including a substance that absorbs the wavelength of the light source used for image recording, except when a black image is obtained. The substance that absorbs the wavelength of the light source may be either a pigment or a dye, but in the case of obtaining a color image, an infrared light source such as a semiconductor laser is used for image recording, and there is little absorption in the visible region. It is preferable for color reproduction to use a dye having a large absorption of the wavelength of the light source. Examples of near infrared dyes include
The compounds described in JP-A-3-103476 can be mentioned.

For the image forming layer, a coating solution in which a pigment and the binder and the like are dissolved or dispersed is prepared.
Was applied on top, it can be provided by drying.
Examples of the solvent used for preparing the coating solution include n-propyl alcohol, methyl ethyl ketone, propylene glycol monomethyl ether (MFG), methanol, water and the like. The coating and drying can be carried out by using ordinary coating and drying methods.

[0108] Incidentally, in the thermal transfer sheet, instead of providing the heat-sensitive release layer independent, with the addition of sensitive heat material in the light-to-heat conversion layer coating liquid to form a photothermal conversion layer, and a light-heat conversion layer and the heat-sensitive release layer It is also possible to have a configuration that doubles as a combination.

It is preferable that the coefficient of static friction of the outermost layer of the thermal transfer sheet on the side where the image forming layer is coated is 0.35 or less, preferably 0.20 or less. By setting the coefficient of static friction of the outermost layer to 0.35 or less, it is possible to eliminate stains on the roll when the thermal transfer sheet is conveyed and to improve the quality of the formed image. The measuring method of the static friction coefficient is Japanese Patent Application No. 2000-85759.
Paragraph (0011) in accordance with the method described above. Smoother value on the surface of the image forming layer is 0.5 to 50 mmHg (≒ 0.06 at 23 ℃, 55% RH)
65 to 6.65 kPa) is preferable, and Ra is 0.05 to
The thickness is preferably 0.4 μm, which makes it possible to reduce a large number of microscopic voids in which the image receiving layer and the image forming layer cannot come into contact with each other on the contact surface, which is preferable in terms of transfer and image quality. The Ra value is measured by a surface roughness measuring device (Surfcom,
It can be measured based on JIS B0601 by using, for example, Tokyo Seiki Co., Ltd.). The surface hardness of the image forming layer is preferably 10 g or more with a sapphire needle. After charging the thermal transfer sheet according to the US Federal Test Standard 4046, the charging 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 that can be used in combination with the thermal transfer sheet will be described. [Image-Receiving Sheet] (Layer Structure) The image-receiving sheet is usually a support and a support thereon.
One or more image receiving layers are provided, and if desired, one or more layers of a cushion layer, a peeling layer, and an intermediate layer are provided between the support and the image receiving layer. Further, it is preferable to have a back layer on the surface of the support opposite to the image receiving layer from the viewpoint of transportability.

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

It is preferable that the support has minute voids (voids) because the image quality can be improved. Such a support is, for example, a mixed melt obtained by mixing a thermoplastic resin and a filler composed of an inorganic pigment or a polymer incompatible with the thermoplastic resin into a single layer or a multi-layer by a melt extruder. It can be produced by forming a film and further stretching it monoaxially 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, polyolefin resin such as polypropylene and polyethylene terephthalate resin are preferable because they have good crystallinity, good stretchability and easy formation of voids. It is preferable to use the above-mentioned polyolefin resin or polyethylene terephthalate resin as a main component, and to appropriately use a small amount of another thermoplastic resin together. The inorganic pigment used as the filler preferably has an average particle size of 1 to 20 μm, and calcium carbonate, clay, diatomaceous earth, titanium oxide, aluminum hydroxide, silica or the like can be used. Further, as the incompatible resin used as the filler, when polypropylene is used as the thermoplastic resin, it is preferable to combine polyethylene terephthalate as the filler. Details of the support having minute voids are described in Japanese Patent Application No. 11-290570. The content of the filler such as the inorganic pigment in the support is 2 to 30 by volume.
% Is common.

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

(Image Receiving Layer) In order to transfer and fix the image forming layer on the surface of the image receiving sheet, one or more image receiving layers are preferably provided on the support. The image receiving layer is preferably a layer formed mainly of an organic polymer binder. The binder is preferably a thermoplastic resin, examples of which include acrylic acid, methacrylic acid,
Homopolymers and copolymers of acrylic monomers such as acrylic acid esters and methacrylic acid esters, cellulosic polymers such as methyl cellulose, ethyl cellulose and cellulose acetate, polystyrene, polyvinyl pyrrolidone, polyvinyl butyral, polyvinyl alcohol, polyvinyl chloride, etc. Examples thereof include homopolymers and copolymers of vinyl monomers, 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) of lower than 90 ° C. in order to obtain a proper adhesive force with the image forming layer. For this reason, it is possible to add a plasticizer to the image receiving layer. Further, the binder polymer preferably has a Tg of 30 ° C. or higher in order to prevent blocking between the sheets. The binder polymer of the image-receiving layer is the same as the binder polymer of the image-forming layer in that it improves the adhesion to the image-forming layer during laser recording and improves the sensitivity and image strength.
Alternatively, it is particularly preferable to use a similar polymer.

Smoother value of the image receiving layer surface is 23 ° C, 55% R
It is preferable that H is 0.5 to 50 mmHg (≈0.0665 to 6.65 kPa), and Ra is preferably 0.05 to 0.4 μm, which makes it possible for the image receiving layer and the image forming layer to not come into contact with the contact surface. Can reduce the micro voids in the transfer,
Furthermore, it is preferable in terms of 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 charging the image receiving sheet according to US Federal Test Standard 4046, the charged potential of the image receiving layer 1 second after the image receiving sheet is grounded is preferably -100 to 100V. The surface resistance of the image receiving layer is preferably 10 ⁹ Ω or less at 23 ° C. and 55% RH. The coefficient of static friction on the surface of the image receiving layer is preferably 0.2 or less. The surface energy of the image receiving layer surface is preferably 23 to 35 mg / m ² .

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

Examples of the organic polymer include the image forming layer forming polymer. As the photopolymerization initiator, a general photoradical polymerization initiator such as benzophenone or Michler's ketone is used in a proportion of 0.1 to 20% by mass in the layer.

The image receiving layer has a thickness of 0.3 to 7 μm, preferably 0.7 to 4 μm. When it is 0.3 μm or more, the film strength can be secured at the time of retransfer to the printing paper. By setting the thickness to 4 μm or less, the gloss of the image after retransfer 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 at the time of 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 deformation effect of the cushion layer reduces the gap between the image receiving layer and the image forming layer, resulting in a reduction in the size of image defects such as white spots. You can also do it. Furthermore, 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 the transferability of the image receiving layer can be improved, and the transferred image can also be transferred. By reducing the gloss of the product, the closeness to the printed product can be improved.

The cushion layer is constructed so as to be easily deformed when a stress is applied to the image receiving layer, and in order to achieve the above effect, a material having a low elastic modulus, a material having rubber elasticity, or easily softened by heating. Preferably, it is 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, more preferably 10 to 100.
It is MPa. In addition, in order to insert foreign matter such as dust, the penetration (25
C., 100 g, 5 seconds) is preferably 10 or more. The cushion layer has a glass transition temperature of 80 ° C or lower, preferably 25 ° C or lower, and a softening point of 50 to 200 ° C. It is also possible to suitably add a plasticizer to the binder in order to adjust these physical properties, for example, Tg.

Specific materials used as the binder of 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. Examples thereof include polymer, ethylene-vinyl acetate copolymer, ethylene-acrylic copolymer, vinyl chloride-vinyl acetate copolymer, vinylidene chloride resin, plasticizer-containing vinyl chloride resin, polyamide resin, and phenol resin. The thickness of the cushion layer varies depending on the resin used and other conditions, but is usually 3 to 100 μm,
It is preferably 10 to 52 μm.

The image receiving layer and the cushion layer need to be adhered to each other until the laser recording stage, but they are preferably provided so as to be peelable in order to transfer the image to the actual printing paper. 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 type according to 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, methyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl alcohol, polyvinyl chloride. , Urethane resin,
Fluorine-based resins, polystyrene, styrenes such as acrylonitrile styrene and those obtained by crosslinking these resins, polyamides, polyimides, polyetherimides, polysulfones, polyethersulfones, aramids, etc., Tg of 65 ° C.
The above-mentioned thermosetting resins and cured products of these resins can be mentioned. As the curing agent, general curing agents such as isocyanate and melamine can be used.

If a binder for the release layer is selected according to the above physical properties, polycarbonate, acetal, and ethyl cellulose are preferable from the viewpoint of storability. Further, if an acrylic resin is used for the image receiving layer, release is carried out when the image is retransferred after laser thermal transfer. Since it has good properties, it is particularly preferable. In addition, separately, a layer having extremely low adhesiveness to the image receiving layer upon cooling can be used as the release layer. Specifically, a layer containing a heat-melting compound such as waxes and binders or a thermoplastic resin as a main component can be used. Examples of the heat-meltable compound include the 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, ethylene-based copolymers such as ethylene-vinyl acetate-based resin and cellulose-based resin are preferably used.

If desired, higher fatty acids, higher alcohols, higher fatty acid esters, amides, higher amines, etc. can be added to the release layer as additives.
Another structure of the peeling layer is a layer having peelability by cohesively breaking itself by melting or softening during heating. Such a release layer preferably contains a supercooling substance. Examples of the supercooling substance include poly-ε-caprolactone, polyoxyethylene, benzotriazole, tribenzylamine, vanillin and the like. Further, in the peelable layer having another structure, a compound that reduces the adhesion to the image receiving layer is included. 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; polyethylene. Solid waxes such as wax and amide wax; fluorine-based and phosphoric acid ester-based surfactants and the like can be mentioned. As a method of forming the release layer,
A blade coater, a roll coater, a bar coater, which is obtained by dissolving the material in a solvent or dispersing it in a latex form.
A coating method using a curtain coater, a gravure coater, or the like, an extrusion lamination method using hot melt, or the like can be applied, and it can be formed by coating on the cushion layer. Alternatively, there is a method in which a material obtained by dissolving the raw material in a solvent or dispersed in the form of a latex on a temporary base is applied by the above-mentioned method and the cushion layer is bonded and then the temporary base is peeled off.

The image receiving sheet combined with the thermal transfer sheet may have a structure in which the image receiving layer also serves as a cushion layer. In that case, the image receiving sheet is a support / cushionable image receiving layer or a support / undercoat layer. / It may have a cushioning image-receiving layer. Also in this case, it is preferable that the cushioning image-receiving layer is detachably provided so that the image can be retransferred to the actual printing paper. In this case, the image after retransfer to the actual printing paper has excellent gloss. The thickness of the cushioning image-receiving layer is 5 to 100 μm, preferably 10
Is about 40 μm.

Further, it is preferable that a back layer is provided on the surface of the image receiving sheet opposite to the surface of the support 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 or tin oxide fine particles, and a matting agent such as silicon oxide or PMMA particles to the back layer in order to improve transportability in the recording apparatus. The above additives can be added not only to the back layer but also to the image receiving layer and other layers, if necessary. Although it is not possible to specify the type of additive depending on its purpose,
For example, in the case of a matting agent, particles having an average particle size of 0.5 to 10 μm can be added to the layer in an amount of about 0.5 to 80%. As the antistatic agent, the surface resistance of the layer is 23 ° C., 50
% 10 ¹² Omega less RH for, more preferably 10 ⁹ Omega
As described below, various surfactants and conductive agents can be appropriately selected and used.

As the binder used in the back layer, gelatin, polyvinyl alcohol, methyl cellulose, nitrocellulose, acetyl cellulose, aromatic polyamide resin, silicone resin, epoxy resin, alkyd resin, phenol resin, melamine resin, fluorine resin, polyimide resin. , 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 compound, aromatic ester, fluorinated polyurethane A general-purpose polymer such as polyethersulfone can be used. The use of a crosslinkable water-soluble binder as the binder of the back layer, which is effective in preventing the matting agent from falling off and improving the scratch resistance of the back layer. It is also effective in blocking during storage. This cross-linking means can employ any one or combination of heat, actinic rays, and pressure depending on the properties of the cross-linking agent used without particular limitation. 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, polymethylmethacrylate (PMM
A), polystyrene, polyethylene, polypropylene,
Examples thereof include fine particles of other radical polymerization type polymers, fine particles of condensation polymers such as polyester and polycarbonate. The back layer is preferably provided in an amount of about 0.5 to 5 g / m ² . If it is less than 0.5 g / m ² , the coating property is unstable and problems such as powder drop of the matting agent are likely to occur.
Further, when it is applied over 5 g / m ² , the particle size of a suitable matting agent becomes very large, and the back layer causes the embossing of the image receiving layer surface, especially the thermal transfer for transferring a thin image forming layer. In this case, the recorded image is likely to be missing or uneven. The matting agent preferably has a number average particle size larger by 2.5 to 20 μm than the layer thickness of only the binder of the back layer. Among the matting agents, particles having a particle size of 8 μm or more need to be 5 mg / m ² or more, and preferably 6 to 600 mg /
m ² . This improves especially foreign matter failures.
Also, the value obtained by dividing the standard deviation of the particle size distribution by the number average particle size σ / r
By using a narrow particle size distribution such that n (= coefficient of variation of particle size distribution) is 0.3 or less, defects caused by particles having an abnormally large particle size can be improved.
The desired performance is obtained with a smaller addition amount. More preferably, this coefficient of variation is 0.15 or less.

An antistatic agent is preferably added to the back layer in order to prevent foreign matter from adhering to the back layer due to frictional charging with the transport roll. Examples of the antistatic agent include cationic surfactants, anionic surfactants, nonionic surfactants, polymeric antistatic agents, conductive fine particles, and "1129".
Compounds described in “Chemical products of No. 0”, Kagaku Kogyo Nipposha, pp. 875-876, etc. are widely used. Among the above substances, metal oxides such as carbon black, zinc oxide, titanium oxide and tin oxide, and conductive fine particles such as organic semiconductors are preferably used as the antistatic agent that can be used in the back layer. It is particularly preferable to use the conductive fine particles because the antistatic agent is not dissociated from the back layer and a stable antistatic effect is obtained regardless of the environment. In addition, various activators are added to the back layer in order to impart coatability and releasability.
It is also possible to add a release agent such as silicone oil or fluorine resin. The back layer is particularly preferable when the softening point of the cushion layer and the image receiving layer measured by TMA (Thermomechanical Analysis) is 70 ° C. or lower.

The TMA softening point is determined by observing the phase of the object to be measured while raising the temperature of the object to be measured at a constant temperature rising rate while applying a constant load. In the present invention, the temperature at which the phase of the measurement object begins to change is defined as the TMA softening point. 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 laminated. 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 heating roller. In this case, the heating temperature is preferably 160 ° C or lower, or 130 ° C or lower.

As another method for obtaining a laminated body, the above-mentioned vacuum adhesion method is also suitably used. In the vacuum contact method, the image receiving sheet is first wound on the drum provided with suction holes for vacuuming, and then a thermal transfer sheet having a size slightly larger than that of the image receiving sheet is pressed while the air is uniformly pushed out by the squeeze roller. It is a method of vacuum adhesion to. As another method, there is also a method in which an image receiving sheet is mechanically attached while being pulled on a metal drum, and a thermal transfer sheet is similarly mechanically pulled and attached so as to be in close contact therewith. Among these methods, the vacuum contact method is particularly preferable because it does not require temperature control of a heat roller or the like and facilitates quick and uniform lamination.

[0134]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.
In the text, "part" means "part by mass" unless otherwise specified. —Preparation of Thermal Transfer Sheet K (Black) — [Formation of Back Layer] [Preparation of Back Layer 1 Coating Solution] 2 parts of acrylic resin aqueous dispersion (Jurima-ET410, 20% by mass, manufactured by Nippon Pure Chemical Co., Ltd.) ) Antistatic agent 7.0 parts (tin oxide-antimony oxide aqueous dispersion, average particle size: 0.1 μm, 17% by mass) Polyoxyethylene phenyl ether 0.1 part Melamine compound 0.3 parts (Sumitex Resin M -3, Sumitomo Chemical Co., Ltd.) Distilled water was prepared so that the total amount 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)
0.01 μm) is corona-treated on one surface (back surface), and the back layer is applied with the coating solution for the back layer to a thickness of 0.03 μm, and then dried at 180 ° C for 30 seconds. Was formed. Young's modulus in the longitudinal direction of the support is 450 kg / m
m ² (≈4.4 GPa), Young's modulus in the width direction is 500
It is 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), F-5 value in the support width direction is 13 kg / mm
² (≈127.4 MPa), 100 ° C. of the support,
The heat shrinkage rate in 30 minutes is 0.3% in the longitudinal direction and 0.1% in the width direction. Breaking strength is 20kg / mm in the longitudinal direction
² (≈196 MPa) and 25 kg / mm ² (≈
245 MPa) and the elastic modulus is 400 kg / mm ² (≈3.
9 GPa).

[0136]   [Preparation of coating solution for back layer 2]   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 mass%)   Colloidal silica 2.0 parts     (Snowtex C, 20 mass%, Nissan Chemical Co., Ltd.)   Epoxy compound 0.3 parts     (Dinacol Ex614B, Nagase Kasei Co., Ltd.)   Sodium polystyrene sulfonate 0.1 part   Distilled water reaches 100 copies                                                       Prepared to be

[Formation of Back Second Layer] The back second layer coating solution was applied onto the back first layer to a dry layer thickness of 0.03 μm, and then dried at 170 ° C. for 30 seconds to obtain the back first layer. Was formed.

[Formation of Photothermal Conversion Layer] [Preparation of Photothermal Conversion Layer Coating Liquid] The following components were mixed with stirring with a stirrer to prepare a photothermal conversion layer coating liquid. [Composition of coating liquid for photothermal conversion layer] Infrared absorbing dye 7.6 parts ("NK-2014", manufactured by Japan Photosensitive Dye Co., Ltd., cyanine dye having the following structure)

[0139]

[Chemical 6]

(Wherein R represents CH ₃ and X ⁻ represents ClO ₄ ^— ) 29.3 parts of a polyimide resin having the following structure (“Ricacoat SN-20F”, manufactured by Shin Nippon Rika Co., Ltd., pyrolysis) (Temperature: 510 ℃)

[0141]

[Chemical 7]

(In the formula, R ₁ represents SO _2. R ₂ represents

[0143]

[Chemical 8]

Is shown. ) Exon-naphtha 5.8 parts-N-methylpyrrolidone (NMP) 1500 parts-Methyl ethyl ketone 360 parts-Surfactant 0.5 parts ("Megafuck F-176PF", Dainippon Ink and Chemicals, Inc., F-based interface) Activator) • Matting agent dispersion having the following composition 14.1 part Preparation of matting agent dispersion 10 parts of true spherical silica fine particles having an average particle size of 1.5 μm (Seahost KE-P150 manufactured by Nippon Shokubai Co., Ltd.), dispersing agent polymer ( Acrylic ester styrene copolymer polymer: 2 parts of Junkryl 611) manufactured by Johnson Polymer Co., Ltd., 16 parts of methyl ethyl ketone and 64 parts of N-methylpyrrolidone are mixed and 30 parts of glass beads having a diameter of 2 mm are made of polyethylene having a capacity of 200 ml. It was put in a container and dispersed for 2 hours with a paint shaker (manufactured by Toyo Seiki) to obtain a dispersion of silica fine particles.

[Formation of a photothermal conversion layer on the surface of a support] After coating the above coating solution for a photothermal conversion layer with a wire bar on one surface of a polyethylene terephthalate film (support) having a thickness of 75 μm, The coated material was dried in an oven at 120 ° C for 2 minutes to form a photothermal conversion layer on the support. The optical density of the obtained photothermal conversion layer in the vicinity of a wavelength of 808 nm was measured by a UV-spectrophotometer U manufactured by Shimadzu Corporation.
When measured by V-240, it was OD = 1.03. The layer thickness was 0.3 μm on average when the cross section of the photothermal conversion layer was observed with a scanning electron microscope.

[Formation of Image-Forming Layer] [Preparation of Coating Solution for Black Image-Forming Layer] The following components were put in a kneader mill and shearing force was applied while adding a small amount of solvent to carry out a pretreatment for dispersion. It was To the dispersion, a solvent is further added to finally prepare 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 • Polyvinyl butyral 12.6 parts (“S-REC B BL-SH”, manufactured by Sekisui Chemical Co., Ltd.) • Pigment Black (Pigment Black) 7 (carbon black C.I. 77266) 4.5 parts ("Mitsubishi Carbon Black # 5", manufactured by Mitsubishi Chemical Co., Ltd., PVC blackness: 1) -Dispersion aid 0.8 parts ("Solspers S-20000", manufactured by ICI Co., Ltd.) -N-Propyl alcohol 79.4 parts Composition 2-Polyvinyl butyral 12.6 parts ("S-REC B BL-SH", Sekisui Chemical Co., Ltd.)-Pigment Black (Pigment Black) 7 (carbon black C.I. No. 77266) 10.5 parts ("Mitsubishi Carbon Black MA100", manufactured by Mitsubishi Chemical Corporation, PVC blackness: 10) -Dispersion aid 0.8 parts ("Solspers S-20000", manufactured by ICI Corporation) -n-Propyl alcohol 79.4 parts

Next, the following components were mixed with stirring with a stirrer to prepare a coating liquid for black image forming layer. [Composition of coating liquid for black image-forming layer] -Black pigment dispersion mother liquor 185.7 parts Composition 1: Composition 2 = 70:30 (parts) -Polyvinyl butyral 11.9 parts ("S-REC B BL-SH", Sekisui Chemical Co., Ltd.) Kogyo Co., Ltd.-Wax compound (stearic acid amide "Nutron 2", manufactured by Nippon Seika Co., Ltd.) 1.7 parts (behenic acid amide "Diamid BM", manufactured by Nippon Kasei Co., Ltd.) 1 0.7 parts (lauric 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 (erucic acid amide " 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 ( (Components: 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 ("Megafuck F-176PF", solid content 20%, manufactured by Dainippon Ink and Chemicals, Inc.)-Inorganic pigment 7.1 parts ("MEK-ST", 30% methyl ethyl ketone solution, Nissan Chemical Co., Ltd.) -N-propyl alcohol 1050 parts-Methyl ethyl ketone 295 parts Particles in the obtained black image-forming layer coating solution were measured using a laser scattering type particle size distribution measuring device, and found to have an average particle size of 0.25 μm. Yes, the proportion of particles of 1 μm or larger was 0.5%.

[Formation of Black Image Forming Layer on Surface of Photothermal Conversion Layer] The coating solution for black image forming layer was applied to the surface of the photothermal converting layer for 1 minute by using a wire bar, and then the coated product was heated to 100 ° C. Dry in the oven for 2 minutes,
A black image forming layer was formed on the photothermal conversion layer. Through the above steps, the photothermal conversion layer and the black image forming layer are provided on the support in this order, and the thermal transfer sheet (hereinafter,
It is referred to as a thermal transfer sheet K. Similarly, a yellow image forming layer provided with an image forming layer is referred to as a thermal transfer sheet Y, a magenta image forming layer provided is referred to as a thermal transfer sheet M, and a cyan image forming layer provided is referred to as a thermal transfer sheet C).
Was produced. The optical density (optical density: OD) of the black image forming layer of the thermal transfer sheet K was measured by a Macbeth densitometer “TD-
904 "(W filter), OD =
It was 0.91. Further, the layer thickness of the black image forming layer was measured and found to be 0.60 μm on average.

The physical properties of the image forming layer thus obtained were as follows. The surface hardness of the image forming layer is 10g with a sapphire needle.
The above is preferable, and specifically, it was 200 g or more. The smoother value of the surface is 0.5 to 50 mmHg at 23 ° C and 55% RH (≒
0.0665 to 6.65 kPa) is preferable, specifically 9.3 m
It was mHg (≈1.24 kPa). The coefficient of static friction on the surface is preferably 0.2 or less, and 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 layer thickness was 0.60 μm, and the OD / layer thickness was 3.03. The deformation rate of the photothermal conversion layer was 168% 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 Y— Preparation of thermal transfer sheet K except that a yellow image forming layer coating solution having the following composition was used in place of the black image forming layer coating solution in the preparation of thermal transfer sheet K. A thermal transfer sheet Y was produced in the same manner as. 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: -Polyvinyl butyral 7.1 parts ("S-REC B BL-SH", manufactured by Sekisui Chemical Co., Ltd.)-Pigment Yellow (Pigment Yellow) 180 (CINN) o.21290) 12.9 parts ("Novoperm Yellow (Novopalm Yellow) P-HG", manufactured by Clariant Japan Co., Ltd.) ・ Dispersion aid 0.6 parts ("Solspers S-20000", manufactured by ICI Co., Ltd.) ) -N-Propyl alcohol 79.4 parts [Yellow pigment dispersion mother liquor composition] Yellow pigment composition 2: -Polyvinyl butyral 7.1 parts ("S-REC B BL1-SH", Sekisui Chemical Co., Ltd.)-Pigment Yellow ( Pigment Yellow) 139 (CINNO 56298) 12.9 parts (" Ovoperm 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

[0151] [Coating liquid composition for yellow image forming layer] -126 parts of the above yellow pigment dispersion mother liquor     Yellow pigment composition 1: Yellow pigment composition 2 = 95: 5 (parts) ・ Polyvinyl butyral 4.6 parts ("S-REC B BL-SH", Sekisui Chemical Co., Ltd.) ・ Wax compounds (Stearic acid amide "Nutron 2", manufactured by Nippon Seika Co., Ltd.) 0.7 parts (Behenamide “Diamid BM”, manufactured by Nippon Kasei Co., Ltd.) 0.7 parts (Lauric acid amide "Diamid Y", manufactured by Nippon Kasei Co., Ltd.) 0.7 parts (Palmitic acid amide "Diamit KP", manufactured by Nippon Kasei Co., Ltd.) 0.7 parts (Eruca acid amide "Diamid L-200", manufactured by Nippon Kasei Co., Ltd.) 0.7 parts (Oleic acid amide "Diamid O-200", manufactured by Nippon Kasei Co., Ltd.) 0.7 parts ・ Nonionic surfactant 0.4 parts ("Chemist 1100", Sanyo Kasei Co., Ltd.) ・ Rosin 2.4 parts ("KE-311", manufactured by Arakawa Chemical Co., Ltd.) ・ Surfactant 0.8 parts ("Megafuck F-176PF", solid content 20%, manufactured by Dainippon Ink and Chemicals, Inc. ) ・ N-propyl alcohol 793 parts ・ Methyl ethyl ketone 198 parts

The physical properties of the obtained image forming layer were as follows. The surface hardness of the image forming layer is 10g with a sapphire needle.
The above is preferable, and specifically, it was 200 g or more. The smoother value of the surface is 0.5 to 50 mmHg at 23 ° C and 55% RH (≒
0.0665 to 6.65 kPa) is preferred, specifically 2.3 m
It was mHg (≈0.31 kPa). The coefficient of static friction on the surface is preferably 0.2 or less, and specifically 0.1. The surface energy was 24 mJ / m ² . The contact angle of water was 108.1 °. Reflection optical density is 1.01
And the layer thickness is 0.42 μm and the OD / layer thickness is 2.40.
Met. The deformation rate of the photothermal conversion layer was 150% when recorded with a laser beam whose light intensity on the exposed surface was 1000 W / mm ² or more at a linear velocity of 1 m / sec or more.

-Preparation of Thermal Transfer Sheet M- Preparation of thermal transfer sheet K, except that a magenta image forming layer coating solution having the following composition was used in place of the black image forming layer coating solution in the preparation of thermal transfer sheet K described above. A thermal transfer sheet M was produced in the same manner as. The image forming layer of the resulting thermal transfer sheet M had a layer thickness of 0.38 μm. [Magenta Pigment Dispersion Mother Liquor] Magenta Pigment Composition 1; -Polyvinyl butyral 12.6 parts ("Denka Butyral # 2000-L", manufactured by Denki Kagaku Kogyo KK, Vicat softening point 57 ° C) -Pigment Red (Pigment Red) 57: 1 (C.I. No. 1 5850: 1) 15.0 parts ("Symuller Brilliant Carmine 6B-229", manufactured by Dainippon Ink and Chemicals, Inc.)-Dispersion aid 0. 6 parts ("Solspers S-20000", manufactured by ICI Co., Ltd.)-N-propyl alcohol 80.4 parts [Magenta pigment dispersion mother liquor composition] Magenta pigment composition 2; -Polyvinyl butyral 12.6 parts ("Denka Butyral # 2000 -L ", manufactured by Denki Kagaku Kogyo Co., Ltd., Vicat softening point 57 ° C) ment Red (Pigment Red) 57: 1 (CI. No. 1 5850: 1) 15.0 parts (“Lionol Red (Rionol Red) 6B-4290G”, manufactured by Toyo Ink Mfg. Co., Ltd.) Agent 0.6 parts ("Solspers S-20000", manufactured by ICI Corporation) -n-Propyl alcohol 79.4 parts

[0154] [Coating liquid composition for magenta image forming layer] 163 parts of the above-mentioned magenta pigment dispersion mother liquor     Magenta pigment composition 1: Magenta pigment composition 2 = 95: 5 (part) ・ Polyvinyl butyral 4.0 parts ("Denka Butyral # 2000-L", manufactured by Denki Kagaku Kogyo Co., Ltd., Vicat softening 57 ° C) ・ Wax compounds (Stearic acid amide "Nutron 2", manufactured by Nippon Seika Co., Ltd.) 1.0 part (Behenamide “Diamid BM”, manufactured by Nippon Kasei Co., Ltd.) 1.0 part (Lauric acid 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 (Eruca acid amide "Diamind L-200", manufactured by Nippon Kasei Co., Ltd.) 1.0 part (Oleic acid amide "Diamid O-200", manufactured by Nippon Kasei Co., Ltd.) 1.0 part ・ Nonionic surfactant 0.7 parts ("Chemist 1100", Sanyo Kasei Co., Ltd.)  ・ Rosin 4.6 Department ("KE-311", manufactured by Arakawa Chemical Co., Ltd.) ・ Pentaerythritol tetraacrylate 2.5 parts (“NK Ester A-TMMT”, manufactured by Shin Nakamura Chemical Co., Ltd.) ・ Surfactant 1.3 parts ("Megafuck 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 image forming layer thus obtained were as follows. The surface hardness of the image forming layer is 10g with a sapphire needle.
The above is preferable, and specifically, it was 200 g or more. The smoother value of the surface is 0.5 to 50 mmHg at 23 ° C and 55% RH (≒
0.0665 to 6.65 kPa) is preferred, specifically 3.5 m
It was mHg (≈0.47 kPa). The coefficient of static friction on the surface is preferably 0.2 or less, and 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 layer thickness was 0.38 μm, and the OD / layer thickness was 3.97. The deformation ratio of the photothermal conversion layer was 160% when recorded with a laser beam having a light intensity of 1000 W / mm ² or more on the exposed surface at a linear velocity of 1 m / sec or more.

-Preparation of Thermal Transfer Sheet C-Preparation of thermal transfer sheet K except that a cyan image forming layer coating solution having the following composition was used in place of the black image forming layer coating solution in the preparation of the thermal transfer sheet K. A thermal transfer sheet C was produced in the same manner as. The layer thickness of the image forming layer of the obtained thermal transfer sheet C was 0.45 μm. [Cyan Pigment Dispersion Mother Liquor] Cyan Pigment Composition 1: Polyvinyl butyral 12.6 parts (“S-REC B BL-SH”, manufactured by Sekisui Chemical Co., Ltd.) Pigment Blue 15: 4 (CI) No. 74160) 15.0 parts ("Cyanine Blue (Cyanine Blue) 700-10FG", manufactured by Toyo Ink Mfg. Co., Ltd.)-Dispersion aid 0.8 parts ("PW-36", Kusumoto Kasei Co., Ltd.)・ N-propyl alcohol 110 parts [Cyan pigment dispersion mother liquor composition] Cyan pigment composition 2: ・ Polyvinyl butyral 12.6 parts (“S-REC B BL-SH”, Sekisui Chemical Co., Ltd.) ・ Pigment Blue (Pigment Blue) Blue) 15 (C.I. No. 74 160) 15.0 parts ("Lionol Blue (Lionol Blue 7027 ", manufactured by Toyo Ink Mfg Co., Ltd.) Dispersion aid 0.8 parts (" PW-36 ", manufactured by Kusumoto Chemicals Ltd.) n-propyl alcohol 110 parts

[0157] [Coating liquid composition for cyan image forming layer] 118 parts of the above mother pigment dispersion of cyan pigment     Cyan pigment composition 1: Cyan pigment composition 2 = 90: 10 (parts) ・ Polyvinyl butyral 5.2 parts ("ESREC B BL-SH", Sekisui Chemical Co., Ltd.) ・ Inorganic pigment "MEK-ST" 1.3 parts ・ Wax compounds (Stearic acid amide "Nutron 2", manufactured by Nippon Seika Co., Ltd.) 1.0 part (Behenamide “Diamid BM”, manufactured by Nippon Kasei Co., Ltd.) 1.0 part (Lauric acid amide "Diamid Y", manufactured by Nippon Kasei Co., Ltd.) 1.0 part (Palmitic acid amide "Diamined KP", manufactured by Nippon Kasei Co., Ltd.) 1.0 part (Eruca amide "Diamid L-200" (manufactured by Nippon Kasei Co., Ltd.) 1.0 part (Oleic acid amide "Diamid O-200", manufactured by Nippon Kasei Co., Ltd.) 1.0 part ・ Rosin 2.8 parts ("KE-311", manufactured by Arakawa Chemical Co., Ltd.) -Pentaerythritol tetraacrylate 1.7 parts (“NK Ester A-TMMT”, manufactured by Shin Nakamura Chemical Co., Ltd.) ・ Surfactant 1.7 parts ("Megafuck F-176PF", solid content 20%, manufactured by Dainippon Ink and Chemicals, Inc. ) ・ N-Propyl alcohol 890 parts ・ Methyl ethyl ketone 247 parts

The physical properties of the image forming layer thus obtained were as follows. The surface hardness of the image forming layer is 10g with a sapphire needle.
The above is preferable, and specifically, it was 200 g or more. The smoother value of the surface is 0.5 to 50 mmHg at 23 ° C and 55% RH (≒
0.0665 to 6.65 kPa) is preferred, specifically 7.0 m
It was mHg (≈ 0.93 kPa). The coefficient of static friction on the surface is preferably 0.2 or less, and 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 layer thickness was 0.45 μm, and the OD / layer thickness was 3.03. The deformation rate of the photothermal conversion layer was 165% when recorded with a laser beam having a light intensity of 1000 W / mm ² or more on the exposed surface at a linear velocity of 1 m / sec or more.

—Preparation of Image Receiving Sheet— A cushion layer coating solution and an image receiving layer coating solution having the following compositions were prepared. 1) Cushion layer coating liquid-Vinyl chloride-vinyl acetate copolymer 20 parts (main binder) ("MPR-TSL", manufactured by Nissin Chemical Co., Ltd.)-Plasticizer 10 parts ("Parplex G-40 , CP.HALL.COMPANY Co., Ltd.-Surfactant (fluorine-based: coating aid) 0.5 part ("Megafuck F-177", Dainippon Ink and Chemicals, Inc.)-Antistatic agent ( Quaternary ammonium salt) 0.3 parts ("SAT-5 Super (IC)", manufactured by Nippon Pure Chemical Industries, Ltd.)-Methyl ethyl ketone 60 parts-Toluene 10 parts-N, N-dimethylformamide 3 parts

[0160] 2) Coating liquid for image receiving layer ・ Polyvinyl butyral 8 parts ("ESREC B BL-SH", Sekisui Chemical Co., Ltd.) ・ Antistatic agent 0.7 parts ("Sunstat 2012A", manufactured by Sanyo Kasei Co., Ltd.) ・ Surfactant 0.1 parts ("Megafuck F-177", manufactured by Dainippon Ink and Chemicals, Inc.) ・ 20 parts of n-propyl alcohol ・ Methanol 20 parts ・ 1-Methoxy-2-propanol 50 parts

Using a narrow coater, a white PET support ("Lumirror # 130E58", manufactured by Toray Industries, Inc., thickness 1
30 μm), the above coating solution for forming a cushion layer is applied, the coating layer is dried, and then the image receiving layer coating solution is applied.
Dried. The thickness of the cushion layer after drying is about 20 μm,
The coating amount was adjusted so that the layer 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 a titanium oxide-containing polyethylene terephthalate layer (thickness: 7 μm, titanium oxide content: 2%) provided on both sides thereof. It is a void-containing plastic support consisting of (total thickness: 130 μm, specific gravity: 0.8). The produced material was wound in a roll form, stored at room temperature for 1 week, and then used for image recording with the following laser light. The physical properties of the obtained image receiving layer were as follows. Surface roughness Ra 0.4 to 0.01
μm was preferable, and specifically, it was 0.02 μm. The waviness of the surface of the image receiving layer is preferably 2 μm or less, and specifically 1.2 μm. The smoother value of the surface of the image receiving layer is 0.5 to 50 mmHg (≈0.0665 to 6.65 kP at 23 ° C and 55% RH).
a) is preferable, and specifically, 0.8 mmHg (≈0.11
kPa). Coefficient of static friction on the surface of the image receiving layer is 0.8
The following was preferable, and specifically it was 0.37. The surface energy of the surface of the image receiving layer was 29 mJ / m ² . The contact angle of water was 85.0 °.

-Formation of Transferred Image- The image forming system is the system shown in FIG. 3, using Luxel FINALPROOF5600 as a recording device, and the image forming sequence of this system (completely automatic feeding of the sample supplied in a roll state) and book. An image transferred to the real paper was obtained by the real paper transfer method used in the system. The image-receiving sheet (56 cm × 79 cm) produced above was wound around a rotary drum having a diameter of 38 cm in which a vacuum section hole having a diameter of 1 mm (one area density in an area of 3 cm × 8 cm) was formed, and vacuum adsorption was performed. Then, the thermal transfer sheet K (black) cut into 61 cm × 84 cm was stacked so as to be evenly protruded from the image receiving sheet, and was squeezed by a squeeze roller while being closely adhered to the section holes so that air was sucked. The degree of pressure reduction when the section holes are closed is -150 mmHg (≈81.13) for 1 atm.
kPa). The drum is rotated, and a semiconductor laser beam having a wavelength of 808 nm is condensed from the outside onto the surface of the laminated body on the drum so as to form a spot of 7 μm on the surface of the photothermal conversion layer. (Scanning direction)
On the other hand, a laser image (image line) was recorded on the laminated body while moving in the perpendicular direction (sub-scanning). The laser irradiation conditions are as follows. Further, the laser beam used in this embodiment has 5 rows in the main scanning direction and 3 rows in the sub scanning direction.
A laser beam consisting of a multi-beam two-dimensional array consisting of parallelograms in rows was used.

Laser power 1 10 mW Drum rotation speed 500 rpm Sub-scanning pitch 6.35 μm Environment temperature and humidity 20 ° C. 40%, 23 ° C. 50%, 2
The diameter of the three-condition exposure drum at 6 ° C. and 65% is preferably 360 mm or more, and specifically, the one having a diameter of 380 mm was used. The size of the image is 515 mm × 728 mm, and the resolution is 2600 dpi. When the laminated body on which the laser recording was completed 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 done.

Similarly to the above, the thermal transfer sheet Y,
An image was transferred from the thermal transfer sheets M and C to the image receiving sheet. The transferred four-color image was further transferred to recording paper to form a multicolor image.
Even when laser recording was performed with high energy by the laser light having a three-dimensional array, it was possible to form a multicolor image with good image quality and stable transfer density. 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 as a material of the insertion table and a conveying speed of 15 to 50 mm / sec was used. The Vickers hardness of the heat roll material of the thermal transfer device is 10 to 1
00 is preferable, and specifically, one having a Vickers hardness of 70 was used. The obtained image was good in all three environmental temperatures and humidity.

Here, the method of measuring the reflection optical density and the measurement result will be described. The reflection optical density was obtained by transferring the original paper onto Tokubishi art paper using a densitometer X-rite938 (manufactured by X-rite Co., Ltd.).
M, C and K colors were measured in Y, M, C and K modes, respectively. The reflection optical density and reflection optical density / image forming layer layer thickness of each color are shown in Table 1 below.

[0166]

[Table 1]

[0167]

[Table 2]

The images obtained with the above system configuration were evaluated as follows. (1) Measurement of Reflection Density (OD) of Black Image Area and Calculation of Image Transfer Rate Using the thermal transfer sheet K, the image density of a transfer image obtained under each temperature and humidity condition was measured by using a reflection Macbeth densitometer "RD". −
When measured using "918" (W filter), the reflection density (OD) was as follows. The thermal transfer sheet K was transferred onto an image-receiving sheet without laser recording using a thermal transfer device, and the reflection density (OD) of the obtained black image was measured by the above method.
88, and the image transfer rate by laser recording is 18 ° C.
It was 98.4%, 96.8%, and 96.3% under the temperature and humidity conditions of 30%, 23 ° C 50%, and 26 ° C 65%, respectively.

<Evaluation of Black Image Quality> Using the thermal transfer sheet K, the solid portion and the line drawing portion of the transferred image obtained under each temperature and humidity condition were observed with an optical microscope. No gap was found in the solid part, and the resolution of the line drawing was good, and a black transferred image with little dependence on environmental conditions could be obtained.
The image quality was visually evaluated according to the following criteria. -Solid area- ○: There is no gap during recording or defective transfer. Δ: A gap during recording or a transfer defect partially exists. X: A gap during recording and a transfer defect are present on the entire surface. -Line drawing part-: The edge of the line drawing is sharp and has good resolution. B: The edge of the line drawing is slightly jagged, but bridging does not occur. B: The edge of the line drawing is jagged, but bridging has not occurred. Δ: The edge of the line drawing is jagged, and bridging partially occurs. X: Bridging has occurred on the entire surface.

(2) Dot shape The image obtained in the example formed a halftone dot image corresponding to the number of printed lines at a resolution of 2400 to 2540 dpi. Since each halftone dot had almost no bleeding or chipping and the shape was extremely sharp, it was possible to clearly form halftone dots in a high range from highlight to shadow (Figs. 5 to 12). As a result, it was possible to output high-quality halftone dots with the same resolution as the image setter and CTP setter, and it was possible to reproduce halftone dots and gradation with good print approximation (FIGS. 13 and 14). 2600
Good results were obtained with this product even at a resolution of dpi or higher. (3) Repeatability The product of the present invention obtained in the example has a sharp halftone dot shape, so that halftone dots corresponding to a laser beam can be faithfully reproduced, and the recording characteristics are highly dependent on ambient temperature and humidity. Because it is small, stable repeatability can be obtained for both hue and density.
(FIGS. 15 and 16).

(4) Color Reproduction The thermal transfer sheets of the examples use the color pigments used in the printing inks as the coloring material, and the reproducibility is good, so that highly accurate CMS can be realized. It is almost the same as the hue of the printed part of Japan-Color, and the appearance of the color when the light source such as a fluorescent lamp or an incandescent lamp changes is similar to that of the printed matter. (5) Character quality Since the image obtained in the example has a sharp dot shape,
Fine lines of fine characters were clearly reproduced (Fig. 17, Fig. 1
8).

Next, the following evaluations were further carried out on the color image prepared at a temperature and humidity of 23 ° C. and 50% environmental humidity. The results are also shown in Table 2.

(6) Evaluation of color tone of black portion The color tone of the black portion of the color image transferred to the recording paper was visually evaluated and classified into the following three ranks. ◯: The part that is transferred with being overlapped with other colors has no yellowish or reddish color and is good. Δ: The portion transferred with overlapping other colors has a slight yellowish tint or reddish tint, but is practically acceptable. X: The portion transferred with being overlapped with other colors has a yellowish tint or a reddish tint, which is practically unacceptable. As a result, Example 1 and the following Comparative Example 5 In good color tone is obtained, it was both below Comparative Examples 1 to 4 as defective. (7) Evaluation of white spots The number of white spots having a diameter of 1 mm or more in the color image transferred to a recording paper having a size of 515 mm × 728 mm was counted. ((Comparative Example)) Comparative Examples 1 to 4: Comparative Examples 1 to 4 are performed in the same manner as in Example 1 except that the same sample as in Example 1 is used and the order of image formation is changed as shown in Table 2. Carried out. Comparative Example 5 Comparative Example 5 was carried out in the same manner as in Example 1 except that the pigment in each of the yellow, magenta, cyan and black image forming layers was multiplied by 0.5. However, the optical density of the image forming layer was adjusted to that in Example 1 . The ratio Comparative Examples 1 to 5 of the samples for environmental temperature and humidity 23 ° C. 50% black image to create a color image quality, black portions of the color tone was evaluated in white spots. The above results are shown in Table 2.

[0174]

The proof product developed in the present invention incorporates the above-mentioned various techniques in order to solve the new problems in the laser thermal transfer system and further improve the image quality based on the thin film transfer technique. Achieves sharp halftone dots with the thin-film thermal transfer method, actual paper transfer, actual halftone dot output, pigment type, B2
We were able to develop a laser thermal transfer recording system for DDCP, which consists of a size image forming material, an output machine and high-quality CMS software. As described above, according to the present invention, it is possible to realize a system configuration in which the ability of a material having high resolution can be sufficiently exhibited. Specifically, we can provide proofs and contract proofs that can replace film proofs and analog color proofs in the CTP era, and this color proof matches the color reproduction of printed materials and analog color proofs for customer approval. Can be reproduced. The same pigment-based coloring material as the printing ink is used, transfer to the actual paper is possible, and a DDCP system without moire can be provided. Further, according to the present invention, a large size (A2 / B2 or more) digital direct color proof system, which can transfer onto a paper sheet, uses the same pigment-based coloring material as the printing ink, and has a high similarity to printed matter, can be provided. The present invention is a method in which a laser thin film thermal transfer method is used and a pigment color material is used to perform actual halftone dot recording and transfer to actual paper. Multi-beam 2 under different temperature and humidity conditions
It is possible to provide a multicolor image forming method capable of forming an image having a good transfer quality and a stable transfer density on an image receiving sheet even when laser recording is performed with high energy by a laser beam having a three-dimensional array.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a laser thermal transfer recording device.

FIG. 2 is a diagram showing a configuration example of a thermal transfer device.

FIG. 3 is a diagram showing a configuration example of a system using a laser thermal transfer recording device FINALPROOF.

FIG. 4 is a diagram illustrating an outline of a mechanism of multicolor image formation by thin film thermal transfer using a laser.

FIG. 5 shows dot shapes of images obtained in the examples. The distance between the dot centers is 125 μm.

FIG. 6 shows dot shapes of images obtained in the examples. The distance between the dot centers is 125 μm.

FIG. 7 shows dot shapes of images obtained in the examples. The distance between the dot centers is 125 μm.

FIG. 8 shows dot shapes of images obtained in the examples. The distance between the dot centers is 125 μm.

FIG. 9 shows dot shapes of images obtained in the examples. The distance between the dot centers is 125 μm.

FIG. 10 shows dot shapes of images obtained in the examples.
The distance between the dot centers is 125 μm.

FIG. 11 shows dot shapes of images obtained in the examples.
The distance between the dot centers is 125 μm.

FIG. 12 shows dot shapes of images obtained in the examples.
The distance between the dot centers is 125 μm.

FIG. 13 shows dot shapes of images obtained in the examples.
The distance between the dot centers is 125 μm.

FIG. 14 shows dot reproducibility of the images obtained in the examples. The vertical axis represents the dot area ratio calculated from the reflection density, and the horizontal axis represents the dot area ratio of the input signal.

FIG. 15 is a graph showing the reproducibility of the images obtained in the example L
Shown on the a ^* b ^* plane of the ^* a ^* b ^* color system.

FIG. 16 shows the reproducibility of the images obtained in the examples.

FIG. 17 shows the 2-point character quality of the images obtained in the examples. A positive image is shown.

FIG. 18 shows the 2-point character quality of the images obtained in the examples. A negative image is shown.

[Explanation of symbols]

1 recording device 2 recording head 3 Sub-scanning rail 4 recording drum 5 Thermal transfer sheet loading unit 6 Image-receiving sheet roll 7 Conveyor rollers 8 squeeze roller 9 cutter 10 Thermal transfer sheet 10K, 10C, 10M, 10Y Thermal transfer sheet roll 12 Support 14 Photothermal conversion layer 16 Image forming layer 20 Image receiving sheet 22 Support for image receiving sheet 24 Image receiving layer 30 stacks 31 discharge stand 32 Waste port 33 outlet 34 air 35 waste box 42 original paper 43 Heat roller 44 insertion table 45 Mark indicating the mounting position 46 Insert roller 47 Guide made of heat-resistant sheet 48 peeling nail 49 Guide plate 50 outlet

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI B41M 5/26 S

Claims (10)

(57) [Claims] 1. An image receiving sheet having an image receiving layer, and at least four or more types of thermal transfer sheets having at least a photothermal conversion layer and an image forming layer on a support are used, and the image forming layer of each thermal transfer sheet and the image receiving sheet are used. The image receiving layer and the image receiving layer are placed facing each other and irradiated with laser light, and the laser light irradiation area of the image forming layer is transferred onto the image receiving layer of the image receiving sheet , and further exposed.
The image forming layer transferred onto the image receiving layer of the image receiving sheet.
In a multicolor image forming method having a step of transferring an image onto paper and recording an image, the thermal transfer sheet is composed of at least four types of thermal transfer sheets of yellow, magenta, cyan, and black, and the image forming layer of each thermal transfer sheet is , Of photothermal conversion layer
Directly above, the ratio of optical density (OD) and layer thickness (μm unit) of the image forming layer of each of the thermal transfer sheets is OD / layer thickness of 1.5.
0 or more, and the recording area of the multicolor image of each thermal transfer sheet is 515 mm
X 728 mm or more, the resolution of the transferred image is 2400 dpi or more, and after the image is recorded on the laser light irradiation region of the photothermal conversion layer.
(A), and the cross-sectional area before image recording was (b)
Sometimes, the deformation rate = {(a + b) / (b)} × 100 is 1
It is 10% or more, and receives the image forming layer in the laser irradiation region in a thin film state.
It is transferred to a sheet, and the multi-color image forming method, characterized in that the order of recording each thermal transfer sheet to the image receiving sheet is black, cyan, magenta, yellow order. 2. After transferring from the image receiving sheet to a real paper,
Yellow order of proximity to the support in the present paper, magenta, cyan, multicolor image forming method according to claim 1, wherein the black image forming layer, characterized in that it is transcribed. 3. A thermal transfer sheet of four or more types of yellow, magenta, cyan, and black and an image receiving sheet are supplied in a roll state to a recording apparatus, and the respective sheets are fed out and automatically conveyed in the recording apparatus. The multicolor image forming method according to claim 1 or 2, wherein 4. The resolution of the transferred image is 2600 dpi.
Claims 1 to 3, characterized in that the above image
The method for forming a multicolor image according to any one of 1. 5. The ratio OD / layer thickness of the optical density (OD) and the layer thickness (unit: μm) of the image forming layer of each thermal transfer sheet is 1.
It is 80 or more, The multicolor image forming method of any one of Claim 1- Claim 4 characterized by the above-mentioned. 6. The ratio OD / layer thickness of the optical density (OD) and the layer thickness (μm unit) of the image forming layer of each thermal transfer sheet is 2.
It is 50 or more, The multicolor image forming method of any one of Claim 1- Claim 5 characterized by the above-mentioned. 7. The contact angles of water of the image forming layer of each thermal transfer sheet and the image receiving layer of the image receiving sheet are 7.0 to 7.0.
Claim, characterized in that in the range of 120.0 ° 1
The multicolor image forming method according to claim 6 . 8. The recording area of the multicolor image is 598 × 84.
Claim, characterized in that the size of more than 1 mm 1 ~
The multicolor image forming method according to claim 7 . 9. The ratio OD / layer thickness of the optical density (OD) and the layer thickness (μm unit) of the image forming layer of each thermal transfer sheet is 1.
Is 80 or more, claims 1 to 8 for the contact angle with water of the image receiving sheet is equal to or less than 86 degrees
The method for forming a multicolor image according to any one of 1. 10. An image receiving sheet having an image receiving layer and at least four or more types of thermal transfer sheets having at least a photothermal conversion layer and an image forming layer on a support are used, and the image forming layer of each thermal transfer sheet and the image receiving sheet are used. superimposed to face the image receiving layer is irradiated with laser light, the multi-color image it has copy rolling <br/> image recording with laser light irradiation area of the image forming layer in a thin film state to the image-receiving sheet of the image receiving layer In the forming apparatus, the thermal transfer sheet is at least yellow, magenta, cyan,
And it consists of four or more types of thermal transfer sheet of black, before
The image forming layer of each thermal transfer sheet is directly above the photothermal conversion layer.
There, the optical density of the image forming layer of each thermal transfer sheet (O
D) and the layer thickness (μm unit), the ratio OD / layer thickness is 1.50 or more, and the recording area of the multicolor image of each thermal transfer sheet is 5
15 mm × a size of more than 728 mm, the resolution of the transferred image is not less than 2400 dpi, the light-to-heat conversion layer
The cross-sectional area after image recording for the laser beam irradiation area
(A), when the cross-sectional area before image recording is (b),
Form factor = {(a + b) / (b)} x 100 is 110% or more
And, the order of recording each of the thermal transfer sheet on the image receiving sheet is black, cyan, magenta, yellow order, a sheet supply unit for supplying each thermal transfer sheet and the image receiving sheet in a roll state, A multi-color image forming apparatus, comprising: a sheet conveying unit for feeding and automatically conveying each supplied sheet.