JPH0336414B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to improvements in a method and apparatus for forming a color image by thermal development and thermal transfer using a diffusion transfer type photothermographic material and an image receiving material. (Prior Art) Diffusion transfer type heat-developable photosensitive materials, in which a color image is obtained by separating a silver image and a dye by releasing a diffusible dye by heat development and transferring the dye to an image-receiving layer, are used, for example. Japanese Patent Publication No. 59-124339, same
No. 59-181345, No. 59-159159, No. 59-166954
No. 57-179840, No. 57-186744, No. 58-
No. 149046, No. 59-168439, No. 59-174834, No. 149046, No. 59-168439, No. 59-174834, No.
No. 59-174835, No. 59-174832, No. 59-174833
No., Patent Application No. 58-109293, No. 59-181604, No. 59
−182507, No. 59-179657, No. 59-18250,
In addition to the above-mentioned publications and specifications, the image forming method using the above-mentioned photothermographic material and image-receiving sheet is also described in JP-A No. 59-182785 and the specification. 59−158289
No. 59-124332, No. 59-156791, patent application 1982
It is known from various publications and specifications such as No. -97907, No. 58-128600, and No. 58-237965. Such diffusion transfer type heat-developable photosensitive materials (hereinafter referred to as
Regarding the development processing method for heat-developable photosensitive materials, see Japanese Patent Application No. 58-247986, No. 58-247989,
As described in various specifications such as No. 59-2318, after exposure, an image receiving sheet having a dye fixing portion is brought into close contact with the photothermographic material, so that the photosensitive layer of the photosensitive material and the dye fixing layer are brought into close contact with each other. a heating process of thermally developing the photothermographic material on which the image-receiving sheets have been superimposed and diffusing and transferring the dye image formed image-wise onto the image-receiving sheet; and a step of peeling the image-receiving sheet from the photothermographic material. It is made up of. Among the above steps, the step of bringing the image-receiving sheet into close contact with the photothermographic material is usually achieved by heating the two sheets and applying pressure to bring them into close contact. That is, as a typical example, an image-receiving material and a photothermographic material are placed one on top of the other between a pair of rollers that can uniformly heat and apply pressure so that the surface of the dye-fixing layer and the surface of the photosensitive layer are aligned. This is done by passing it through. Next, the two overlapping sheets are uniformly heated and thermally developed to transfer the dye released from the heat-developable photosensitive material to the dye-fixing layer, and then the two sheets are peeled off. This allows an image to be formed on the image-receiving sheet. However, in the conventional heat development thermal transfer process, the adhesion between the image receiving sheet and the photothermographic material is not necessarily good, and the image receiving sheet after peeling shows uneven transfer density due to the uneven adhesion. (Problems to be Solved by the Invention) Accordingly, the present invention provides a method for uniformly and tightly bonding the heat-developable photosensitive material and the image-receiving material when overlapping the diffusion transfer-type photothermographic material and the image-receiving material and performing heat-developable thermal transfer. An object of the present invention is to provide an image forming method and apparatus that can be superimposed on images. (Means for solving the problem) According to the present invention, the above object of the present invention is as follows (1)
This can be achieved by the image forming method described in (2) below and the image forming apparatus described in (2) below. (1) Imagewise exposure is applied to a diffusion transfer type heat-developable photosensitive material, and the photosensitive material is heated within a range where thermal development does not substantially occur to reduce moisture in the photosensitive layer;
An image forming method characterized in that an image-receiving sheet for transferring the color image in the photosensitive material is superimposed on the photosensitive material and thermally developed in close contact with the image-receiving sheet, thereby diffusing and transferring the formed color image onto the image-receiving sheet. (2) Exposure means for irradiating the diffusion transfer type heat-developable photosensitive material with imagewise exposure, heating means for warming the diffusion transfer type photothermographic material after exposure within a range where thermal development does not substantially occur, and heated diffusion transfer. A heat-developable heat-developable photosensitive material and a heat-developable photosensitive material are adhered to each other, and a diffusion transfer-type photothermographic material is developed and a color image formed in an image-wise manner is diffused and transferred to the image-receive sheet. Features of the image forming device. That is, the present invention is characterized by providing a step of warming the heat-developable photosensitive material after imagewise exposure, before the step of overlapping and bringing the diffusion transfer photothermographic material into close contact with the image-receiving sheet. The effects of the present invention obtained by such a method are considered to be based on the following reasons. In general, the above-mentioned diffusion transfer type heat-developable photosensitive materials use a hydrophilic binder in their constituent layers, and a highly hydrophilic substance such as a hydrophilic heat solvent is added to the photosensitive layer. Water is mixed in. One type of image-receiving sheet is made by coating paper or other synthetic polymer sheets with a layer containing a mordant polymer for fixing heat-transferable dyes released from a heat-developable photosensitive material. Preferred mordant polymers include thermoplastic hydrophobic polymers such as polyvinyl chloride and polycarbonate described in Japanese Patent Application Nos. 58-97907 and 58-128600, and vinylpyridine polymers described in U.S. Pat. No. 2,548,564 and the like. US Patent No.
Examples include polymers containing a quaternary amino group described in No. 3709690. Therefore, since the water permeability of the photosensitive layer of a heat-developable photosensitive material is not necessarily high, and especially when a water-impermeable synthetic polymer such as a polyethylene terephthalate film base is used as a support, Since the support has almost no water permeability, the image receiving layer also has insufficient water permeability because the mordant polymer has poor water permeability. Therefore, when the photosensitive material and the image-receiving layer are overlapped, moisture in the photosensitive layer cannot be removed. Therefore, as mentioned above, when the heat-developable photosensitive material and the image-receiving sheet are overlapped, that is, when they are passed through a device that can uniformly heat and pressurize them at the same time, for example, a pair of heating rollers, the minute amount of moisture in the photosensitive layer is removed. Since the water is not removed, the moisture remaining in the photosensitive layer evaporates during the above-mentioned overlapping process or the subsequent uniform heating process for thermal development and thermal transfer, and the moisture remains between the image-receiving layer and the support of the photothermographic material. It is thought that the expansion causes the adhesion between the image-receiving layer and the photosensitive layer to be inhibited. The present invention has been studied and improved from this point of view, and according to the method of the present invention, the adhesion between the image-receiving layer and the photosensitive layer as described above can be significantly improved compared to the conventional method. The temperature required for heating the photothermographic material in the step prior to the step of overlapping and bringing the photothermographic material and the image-receiving sheet into close contact with each other according to the present invention is 80°C to
250°C, preferably in the range of 100°C to 200°C,
The heating time is 0.1 seconds to 60 seconds, preferably 0.5 seconds to 20 seconds. In addition, the heating temperature in the step of superposing the photothermographic material and the image-receiving sheet following the above-mentioned pre-step is 80°C to 250°C,
Preferably it is in the range of 100°C to 200°C. The pressure during the heating is preferably 0.1Kg/cm ² or more and 100Kg/cm ² or less, more preferably 1Kg/cm 2 or more and 50Kg/cm ² or more.
Kg/ ^cm2 or less. In the preheating and subsequent overlapping steps according to the present invention, the heating temperature and time are preferably selected within a range such that thermal development of the photothermographic material does not substantially occur. According to the present invention, after the process of bringing the photothermographic material and the image receiving sheet into close contact with each other is completed, thermal development and thermal transfer are performed while the photothermographic material and the image receiving sheet are in close contact with each other. The heating temperature required for the above thermal development and thermal transfer is in the range of 80°C to 250°C, preferably 120°C to 170°C, and the time is 1.0 seconds to 180 seconds, preferably 1.5 seconds to
The range is 120 seconds. The heating method used for the above-mentioned preheating, thermal development, and thermal transfer may be any method, such as passing between hot plates, heating by contacting with a hot plate, rotating hot drum, or hot roller. Any known method may be used, such as heating the material by holding it in place or in contact with it, heating it by passing it through hot air, or heating it by conveying it along a heat source using rollers, belts, or guide plates, and bringing it into contact with the heat source. Can be done. In addition, layers of conductive materials such as graphite, carbon black, or metal are laminated on a heat-developable photosensitive material, and an electric current is passed through the conductive layers to heat the photosensitive material using the generated Joule heat. You can also do it. Among the above heating steps, in the heating step for development and transfer after the adhesion step, there is no need to apply too high a pressure, preferably 1 Kg/cm ² or less, more preferably 500 g/m ² or less, and even more preferably 100 g/m 2 or less.
The pressure range is below g/cm ² . Further, the adhesion step and the thermal development thermal transfer step may be performed simultaneously. In this process, the heat-developable photosensitive material is heated to 80 to
After heating to 250°C, preferably 100 to 200°C (heating time is in the range of 0.1 to 60 seconds, preferably 0.5 to 20 seconds), while applying a constant pressure necessary for adhesion.
1.0 in the range of 80-250℃, preferably 120-170℃
Heating is performed for 1.5 seconds to 120 seconds, preferably 1.5 seconds to 120 seconds.
The pressure required for close contact is 100 g/cm ² or more, preferably 500 g/cm ² or more. The image forming method of the present invention has been described in detail above. After exposing a heat-developable photosensitive material according to the method of the present invention, the photosensitive material is heated to reduce moisture, and then an image-receiving sheet is superimposed on the photosensitive layer surface and brought into close contact with the photosensitive material. After heat development and thermal transfer, the dye image released from the heat-developable photosensitive material is diffusely transferred to an image-receiving sheet, and then the image-receiving sheet is peeled from the photothermographic material to achieve high-quality transfer without uneven transfer. A color image is formed on the image receiving layer. The image exposure method for recording a latent image on the heat-developable photosensitive material according to the present invention includes a full-surface exposure method as in a normal color printer, or a scanning exposure method by optically converting computer data and video signals. Good too. Therefore, examples of light sources include generally tungsten lamps, mercury lamps, halogen lamps such as iodine lamps, and others such as CRT, OFT, LED, and laser. In addition, in the process of separating the heat-developable photosensitive material from the image-receiving sheet, in order to peel off the image-receiving material after transfer from the heat-developable photosensitive material, for example, Japanese Patent Application No. 58-147989
Means as described in the specification of the present invention and other known means can be used. Also, when the temperature of the photothermographic material is low (for example,
Development and transfer do not proceed much at temperatures below 80℃ or below, so after cooling to below 80℃ or below 60℃,
You may also peel it off with your fingers. Hereinafter, the present invention will be specifically explained with reference to embodiments shown in the drawings. Example 1 First, a method for preparing a heat-developable photosensitive material and an image-receiving sheet will be described below. [Preparation of silver 4-sulfobenzotriazole] 24 g of 4-sulfobenzotriazole and 4
g of sodium hydroxide in ethanol-water (1:
1) Add and dissolve in 300 ml of the mixed solution. 5 in this solution
20 ml of the specified silver nitrate solution was added dropwise. At this time, 5N sodium hydroxide solution was also added dropwise at the same time to bring the pH to 7.
It was maintained at ~8. This solution was stirred at room temperature for 1 hour and then made up to 400 ml with water to prepare a 4-sulfobenzotriazole silver solution containing 20% excess of 4-sulfobenzotriazole. [Preparation of photosensitive material] 470 mg of the following dye-donating polymer (PM-1)
and 30 mg of 1,4-dioctylhydroquinone were dissolved in 2.1 ml of ethyl acetate. This solution was mixed with 3 ml of a 2.5% gelatin aqueous solution containing a surfactant,
After adding water to make 6.5 ml, the mixture was dispersed with a homogenizer to obtain a dispersion of a dye-providing polymer. Mix 4 ml of the above 4-sulfobenzotriazole silver solution and 6 ml of a dye-donating polymer dispersion, and then add 450 ml of polyvinylpyrrolidone (average molecular weight 30,000).
mg, pentaerythritol 120mg, 1,5-pentanediol 420mg and the following reducing agent (R-3)
After adding 200 mg, the pH was adjusted to 5.5 with 3% citric acid. A silver iodobromide emulsion with an average particle size of 0.05 μm was added to this dispersion in an amount of 3×10 ^-4 mol in terms of silver (gelatin 75
After adding water to make up to 14 ml, dry film thickness of 8 μm was deposited on a polyethylene terephthalate support.
A photosensitive layer was coated using a wire bar so that the photosensitive material was coated with a thickness of m. (R-3) [Preparation of image-receiving material] An image-receiving material was prepared by coating polyvinyl chloride at 10 g/m ² on baryta paper. Using the heat-developable photosensitive material and image-receiving material produced as described above, thermal development and thermal transfer were performed using the following image forming apparatus according to the present invention. FIG. 1 is a front view showing a schematic configuration of an image forming apparatus according to the present invention. In the figure, a roll-shaped heat-developable photosensitive material 1 is guided by a guide roller 2 to an exposure position, exposed to an image by an exposure device 3, and heated in advance by a flat plate-shaped heating device 4 provided on a conveyance path. After being
The rolled image-receiving sheet 5 and the photosensitive layer of the heat-developable photosensitive material 1 are overlapped and brought into close contact with each other by heating and pressing a pair of heating roller 6 and pressure roller 7, and the heating roller 6 and pressure roller 7 rotate. Along with this, it is guided by the guide plate 8 and reaches the thermal development transfer section. The thermal development transfer section as an embodiment of the thermal development transfer device according to the present invention is mainly composed of two endless belts stretched vertically and a heat plate heated by a heater. That is, 9 is the driving roller 11a and 11b.
It is an endless belt that is stretched across the belt and can rotate as the driving rollers 11a and 11b rotate.
is an endless belt that is provided below the endless belt 9, is stretched around drive rollers 12a and 12b, and can rotate as the drive rollers 12a and 12b rotate. Inside the endless belt 10 are heaters 13a and 13b as heating members;
A heat plate 14 heated by a and 13b is built-in. The reason for using a plurality of heaters as described above in the present invention is to facilitate adjustment of heating temperature and heat distribution. Further, in the present invention, as shown in the figure, the shape of the contact surface of the heat plate 14 with the endless belt 10 is made into a gentle curved shape, so that an appropriate tension is applied to the endless belt 10, and the upper part of the endless belt 10 and Since the surface in pressure contact with the endless belt 9 can be formed in a curved shape, when the photosensitive material and the image receiving material are transported under heat, it is possible to promote adhesion between the two materials and at the same time prevent the occurrence of transport misalignment. Ru. Heat conduction from the heat plate 14 to the endless belt 10 is also improved. The tension roller 15, which is located at the center of the upper endless belt 9 and is provided in pressure contact with the endless belt 9, applies light pressure to the endless belt 9.
It gives tension to the belt. The heat-developable photosensitive material 1, which has been closely overlapped with the image-receiving sheet 5 as described above, is carried into the heat-developable transfer section configured as described above, and is held between two upper and lower endless belts 9 and 10, and the rotation of the belts Along with this, the image receiving sheet 5 is conveyed in close contact with the image receiving sheet 5, thermally developed, and at the same time, the diffused color image is transferred to the image receiving sheet 5 and sent out from the endless belt. The photothermographic material overlapped with the image-receiving sheet sent out by the endless belts 9 and 10 is taken up by the take-up roller 16 provided at a slightly downward position with respect to the conveyance direction. The image-receiving sheet is peeled off and separated from the photothermographic material by the force, guided by a guide roller 17, cut into a predetermined length by a cutter 18, and accumulated in a sheet form in a storage section 19. The overall license speed in the image forming apparatus of the present invention is 10 mm/sec, the length of the heating device 4 for the photothermographic material is 30 mm, and the heaters 13a and 13 are
The length of b is 300 mm, and in this example, the temperatures of the heating device 4 are 23°C (room temperature), 60°C, 80°C, and 100°C.
℃, 130℃ and 150℃. Further, the temperature of the heating roller 6 used in the step of bringing the photothermographic material and the image receiving sheet into close contact was 150° C., and the pressure between it and the pressure roller 7 was 5 kg/cm ² by spring pressure. The heat development temperature was set at 150℃ and the line speed was 10mm/sec, so the heat development time was approximately 30℃.
It will be seconds. By setting the processing conditions as described above and using the exposed heat-developable photosensitive material and image receiving sheet with an image forming area of 100 mm x 100 mm, a color image is formed on the image receiving sheet by the above-mentioned apparatus, and the transferred image is The characteristics were evaluated and the results are shown below. Among the evaluation values shown in Table 1 below, transfer unevenness was evaluated according to the following criteria. Uneven transfer ×: White missing areas are quite noticeable per 100 cm ²
10 or more △: Up to 2 to 3 white spots per 100 cm ² ○: There are no white spots, but some density unevenness can be seen ◎: A uniform image was obtained with no white spots or density unevenness. .

[Table] As is clear from the results in the table above, as a pre-process to the process of overlapping and heating the photothermographic material and the image-receiving sheet to bring them into close contact with each other, a method is used to reduce the moisture content of the photosensitive layer of the photothermographic material. It has been found that heating can improve transfer unevenness of images formed on image-receiving sheets without adversely affecting image characteristics. Example 2 Using the same photothermographic material and image-receiving sheet described in Example 1 above, thermal development transfer was carried out using an image forming apparatus according to the present invention having the following configuration. FIG. 2 is a front view showing the main structure of an image forming apparatus of the present invention as another embodiment. In the figure, 21 is a drum that rotates in the direction of the arrow, and 22 is a drive roller 23a, 23b, and 23.
It is a conveyor belt stretched by c and is in pressure contact with the rotating drum 21, and rotates together with the drum 21 in the direction of the arrow at the same speed as the drum 21. The above-mentioned conveyor belt 22 according to the present invention is intended to convey a photothermographic material (described later) overlapped with an image-receiving sheet by sandwiching it with the drum 21 and to perform thermal development transfer. In order to increase the pressure contact force, the conveying path is formed in a semicircular shape along the drum 21, and is stretched so as to cover at least 1/2 of the circumference of the drum 21. In the figure, 24 is a heater constituting the above-mentioned heating member. Reference numeral 25 denotes a heat insulating material for cutting off heat from the heater 24. In this embodiment, the heater 24 is shaped like a semi-circle and forms a conveyance path together with the drum 21. Therefore, the heat insulating material 25 is also arranged in the same shape as the heater 24, that is, a semicircle, on the back surface of the heater 24. Next, a thermal development transfer process using an image forming apparatus having a thermal development transfer section configured as described above will be explained. The heat-developable photosensitive material 26 that has been subjected to image exposure using the same exposure device (not shown) as that used in Example 1 is guided by a guide roller 27 and heated in advance by a roller-shaped heating device 28 to form a photosensitive layer. After the moisture content of the image receiving sheet 29 has been reduced, the image receiving sheet 29 is overlapped so that its photosensitive surface is in contact with the image receiving sheet 29. Heat-developable photosensitive material 26 overlaid with image-receiving sheet 29
is brought into close contact with a pair of pressure rollers 30 and heating rollers 31, guided by a guide plate 32, conveyed, and fed into the thermal development transfer section having the above-mentioned structure. The heat-developable photosensitive material 26 and the image receiving sheet 29, which are heated and pressed into close contact with each other by the heating roller 31 and the pressure roller 30, are held between the drum 21 and the conveyor belt 22, which rotate at the same speed, and are conveyed. and heater 2
4 and a heat insulating material 25, the color image is transferred under heat and developed, and at the same time, the color image is diffusely transferred onto the image receiving sheet 29. The heat-developable photosensitive material 26 and the image-receiving sheet 29, which have been thermally developed and transferred in this manner, are separated from each other by dividing the conveyance path into upper and lower sections when being sent out from the drive roller 23c, and are stored respectively. A color image is thus obtained on the image receiving sheet 29. When the photothermographic material and image-receiving sheet used in this embodiment are in the form of a roll, a cutter may be provided at an appropriate location to cut them into a predetermined length. The heating temperature of the roller-shaped heating device 28, the heating roller 31, the heater 24, etc., and the line speed or the pressure roller 30 in this embodiment
The pressing force between the heating roller 31 and the heating roller 31 may be set under substantially the same conditions as in the first embodiment. When the characteristics of the image obtained on the image-receiving sheet were evaluated and transfer unevenness was observed, the results were exactly the same as in Example 1. (Effects of the Invention) In the image forming method or apparatus of the present invention, a pretreatment step of heating the photothermographic material is provided as a pre-process of the heating step to enhance the adhesion between the photothermographic material and the image receiving sheet. The water content in the photosensitive layer was reduced, and the adhesion between the photothermographic material and the image-receiving sheet was improved, resulting in a marked improvement in transfer unevenness.

[Brief explanation of the drawing]

FIG. 1 is a front view showing a schematic configuration of an image forming apparatus as an embodiment of the present invention, and FIG. 2 is a front view showing a main part configuration of an image forming apparatus as another embodiment of the present invention. be. 1 and 26...thermally developable photosensitive material, 5 and 29
...image receiving sheet, 4...flat heating device, 6 and 31...heating roller, 7 and 30...pressure roller,
9, 10 and 22...conveyor belt, 11a, 11
b, 12a, 12b, 23a, 23b and 23
c... Drive roller, 13a, 13b and 24... Heater, 14... Heat plate, 15... Tension roller, 21... Drum, 28... Roller-shaped heating device.

Claims (1)

[Scope of Claims] 1. Imagewise exposure is applied to a diffusion transfer type heat-developable photosensitive material, and the photosensitive material is heated within a range where thermal development does not substantially occur to reduce moisture in the photosensitive layer. An image forming method characterized in that image-receiving sheets to which a color image in the photosensitive material is to be transferred are superimposed and heat-developed in close contact with each other, and the formed color image is diffusely transferred to the image-receiving sheet. 2. Exposure means for irradiating the diffusion transfer type heat-developable photosensitive material with imagewise exposure; heating means for warming the diffusion transfer type photothermographic material after exposure within a range where thermal development does not substantially occur; heated diffusion transfer type heat; It is characterized by having a contact means for overlapping and closely adhering an image-receiving sheet to the development photosensitive material, and a heating means for developing the adhered diffusion transfer type heat-developable photosensitive material and diffusing and transferring a color image formed in an imagewise manner onto the image-receiving sheet. image forming device.