JPH0318704B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an image transfer method, and more particularly to a method for creating a color proof by image transfer in a plate-making process.

Conventional technology When printing a large number of sheets by creating a printing plate using a plate-making material such as a PS plate from a color original, the color original is usually converted into a 4-color halftone negative (or halftone positive) using a color scanner, etc. Once created, a four-color one-sheet body is created through processes such as pasting, turning, and retouching, and proof printing is performed to confirm the finished product before final printing. In this case, check functions such as checking the scanner disassembly in the process of creating a net negative or positive, checking pasting etc. in the process of creating a single-sheet positive, and confirming the printing orderer in the proof printing process are used to ensure a good print finish. Color proofs are created and checked for this purpose. The photosensitive materials for creating this color proof include silver halide photosensitive materials, electrophotographic photosensitive materials,
Photosensitive materials using photopolymers are known, and there are those that use pigments and dyes for color images, and there are both negative and positive systems depending on the purpose of use. An example of a method for creating such a color proof is as follows. First, the photosensitive layer of a photosensitive material having a photosensitive layer on a support is transferred to a transfer paper by pressure and heating, image exposure and development are performed to form a first color image on the transfer paper. Next, a second photosensitive layer is transferred thereon in the same manner, imagewise exposed and developed to form a second color image on the same transfer paper. Repeat this operation for yellow, magenta, cyan,
A multicolor image is formed by performing blacking a total of four times.

In this case, the transfer of the photosensitive layer onto the transfer paper can be carried out by various methods, such as by simply applying pressure or by applying pressure and heating at the same time. For example, one of the roller pairs or The photosensitive layer is transferred by using both as heat rollers and passing the photosensitive material having the photosensitive layer and the transfer paper in a stacked state between them.

In the present invention, a color proof is produced by subjecting a photosensitive material to imagewise exposure and, after development, transferring the resulting image to an image-receiving sheet. In this case, a multicolor image is created by creating yellow, magenta, cyan, and black color images using four sheets of photosensitive material, and sequentially transferring them to the same image-receiving sheet. In this method, unlike a method in which an image is formed by exposing a photosensitive layer transferred onto a transfer paper, the formed image is sequentially transferred one color at a time, so it is necessary to perform image transfer with strict precision. That is, since the image transferability in this case is greatly influenced by the transfer temperature, it is necessary to strictly maintain the temperature during transfer. Conventionally, when using a commonly used transfer device, the heating time is short, so it is necessary to raise the temperature extremely, and the sheet inserted between the rollers expands locally, causing the transfer image to change. Color shift,
It had the disadvantage of causing uneven transfer.

In this case, since both the image sheet and the image-receiving sheet are made of soft materials, the overlaid sheets warp during the image transfer process, that is, when they are pressurized by the heat roller. There is a problem in that the sharpness of the transferred image is reduced due to misalignment between the two sheets or wrinkles during movement. In particular, when creating a color proof, image transfer processing is usually performed four times, so color misregistration becomes an extremely serious problem.

Purpose of the Invention In view of the above-mentioned problems, the present invention provides an image transfer method in which wrinkles do not occur in the superimposed image and both image-receiving sheets, or positional deviation occurs between the two sheets during image transfer processing. The purpose is to

Structure of the Invention The object of the present invention is to provide an image transfer method in which an image transfer process is performed by overlapping an image sheet on which an image is formed and an image receiving sheet that receives the image, or applying pressure or heating. , achieved by an image transfer method characterized in that a supporting plate having good thermal conductivity and rigidity is superimposed on both of the sheets, and a cover sheet is superimposed on the opposite side of the supporting plate, and then image transfer processing is performed. Ru.

Hereinafter, the image transfer method of the present invention will be explained in detail with reference to an embodiment shown in FIG.

Figure A in Figure 1 is a plan view of the positioning plate used in the method of the present invention, Figure B is a side view showing the intermediate state of the method of the present invention, and Figure C is a side view showing the completed state of the method of the present invention. .

In the transfer method of the present invention, first, positioning holes are punched or the like in each image sheet and image receiving sheet on which color separated images are to be formed. after that,
Each image sheet is exposed and developed, the holes are 2 provided in the positioning plate 1 shown in Figure A.
For example, holes that are shaped to correspond to the two pins 2 and 3, such as the circular pin 2 and the oval pin 3, are made. In this way, the combination of the pins 2, 3 of different shapes and the holes corresponding to the pins 2, 3 enables image alignment.

Thereafter, the image receiving sheet 5 is placed on the support plate 4 (see figure B) on which the positioning plate 1 is attached, aligned with the pins 2 and 3, and the image receiving sheet 5 of the color to be transferred first is placed on the support plate 4 (see figure B). The image sheets 6 are similarly aligned and overlapped. Thereafter, a cover sheet 7 is placed over the image sheet 6 so as to cover the lower front portion of the support plate 4, and the positioning plate 1 is removed. Further, although it has been explained that the cover sheet 7 is attached so as to wrap around the lower front side of the support plate 4, the present invention is not limited to this, and the cover sheet 7 may be attached so as to overlap the front side of the support plate 4. Good too.

The support plate 4 is a thin plate made of, for example, aluminum and has good heat conductivity, and its thickness is approximately 0.5 mm in consideration of heat conduction and rigidity. Further, the support plate 4 is provided with holes into which both the pins 2 and 3 are fitted, but the positional accuracy (image alignment) between the image sheet 6 of the second and subsequent colors and the image receiving sheet 5 is particularly important.
In order to achieve this, the surface on which the image sheet 5 is placed is subjected to white alumite treatment so that fine adjustments can be easily made by visual inspection.

The support plate 4 is, for example, a superimposed transfer processed material (support plate 4, image receiving sheet 5, image sheet 6, cover sheet 7 integrated),
It has the effect of giving rigidity to the transferred object when it is held and conveyed (in the direction of the arrow in figure C) by a pair of upper and lower heat rollers while being pressurized and heated, or during other handling. .

For the cover sheet 7, a plastic resin such as PET resin having a thickness of about 100 μm can be used, taking into consideration thermal conductivity and operability.
Further, the surface of the cover sheet 7 may be coated with a silicone coat, a soft resin coat, etc. to prevent adhesion to the image sheet 6. The cover sheet 7 has the function of pressing the image sheet 6 and the image receiving sheet 5 against the support plate 4 to prevent the sheets 5 and 6 from being misaligned, and further has a function of pressing the image sheet 6 and the image receiving sheet 5 against the support plate 4 and preventing displacement of the sheets 5 and 6. This prevents dust adhering to the (heat roller) from adhering to the transferred object, and also prevents the adhesive of the adhesive layer of the image receiving sheet 5 from adhering to the pressing and heating member.
Furthermore, since the support plate 4 has rigidity, it not only improves the workability of carrying it, but also has the effect of preventing displacement during movement.

In addition, when performing image transfer of two or more colors, the image receiving sheet 5 on which the previous transferred image was formed and the next image sheet 6 are positioned using the method described above, and further fine image alignment is performed by visual inspection. After making the adjustment, the above-described transfer processing step is repeated. Note that fine adjustment by visual inspection is preferably performed using light shining from above.

In the embodiment, the support plate 4 is made of aluminum, and the cover sheet 7 is made of PET.
Although resin is used, the present invention is not limited to this. That is, the support plate 4 is not particularly limited as long as it has good thermal conductivity and rigidity.
Further, the cover sheet 7 is not limited to plastic resin as long as it has good heat conduction and ease of handling.
For example, a thin metal plate or the like may be used. Moreover, the support plate 4
Although we have described an example in which white alumite treatment was applied to the surface of
For example, a metal plate coated with white paint may be used.

Effects of the Invention According to the present invention, before the image sheet 6 and the image-receiving sheet 5 are superposed and transferred, the support plate 4 is stacked on the lower side and the cover sheet 7
By covering the upper side with the material, rigidity is imparted to the transfer object and dust is prevented from adhering to the transfer object, making it easier to handle the transfer object and improving the workability of the transfer process.

In addition, by increasing the rigidity of the transferred material, deformation such as warpage when pressurized by a heat roller or the like is prevented, thereby preventing misalignment between the image sheet 6 and the image receiving sheet 5. is prevented, and image clarity is improved.

Furthermore, since the surface of the support plate 4 is treated with white alumite, it is extremely easy to make fine adjustments when aligning images visually, and since it has rigidity, it improves workability when carrying it. Effective in preventing misalignment.

The method of the present invention can also be applied to retransfer from the image-receiving sheet 5 onto a printing paper for test printing and matting of the test print product.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram illustrating one embodiment of the method of the present invention. 1... Positioning plate, 2, 3... Pin, 4... Support plate, 5... Image receiving sheet, 6... Image sheet, 7... Cover sheet.

Claims (1)

[Scope of Claims] 1. In an image transfer method in which an image transfer process is performed by overlapping and pressing an image sheet on which an image is formed and an image receiving sheet that receives the image, or by applying pressure and heating, A supporting plate having good hardness and rigidity is superimposed on both the sheets, and
An image transfer method, characterized in that an image transfer process is performed after a cover sheet is superimposed on the side opposite to the support plate. 2. The image transfer method according to item 1, wherein the support plate is provided with a hole into which a pin for positioning the image sheet and the image receiving sheet is inserted.