JPH0786689B2 - Image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is capable of forming an image by superimposing a single color or multiple colors utilizing the difference in the adhesiveness between the exposed and unexposed portions of the photosensitive layer, Furthermore, the present invention relates to an image forming method capable of forming an image suitable as a prepress proof for color proofing.
More specifically, it relates to an image forming method capable of steadily migrating an image forming material from an exposure cylinder to an impression cylinder without affecting image quality.

[Prior Art] Conventionally, in the printing industry, a prepress proof has been used as a means for confirming the finish, color tone and the like of a final printed matter before printing. This prepress proof has an overlay method and a surprint method, and they are used properly according to the purpose of use.

In the overlay method, each transparent base film is provided with a photosensitive layer corresponding to each color separation (color separation) image, an image is formed on each base film by irradiation with active light and development, and then each base film is visually registered. And stack them. This method is affected by the reflected light from the superposed films, and thus has a drawback that the texture is significantly different from the actual printed matter.

The surprint method is, for example, US Pat.
As disclosed in Nos. 060024 and 3060025, a plurality of images formed on each photosensitive layer corresponding to each color separation image are sequentially transferred to a single image receptor to obtain a prepress proof. To form. Each photosensitive layer may be colored corresponding to each color-separated image, or each transferred image may be colored with powder color toner.

The system disclosed in U.S. Pat. No. 3060023 and the like is a system in which the photosensitive layer and the image receptor are planarly pressed and brought into close contact with each other, heated, and then peeled off. In this method, in which the photosensitive layer and the image receptor are planarly pressure-bonded and then peeled off, the reproduction of the transferred image becomes unstable unless the working conditions such as the peeling speed and direction are constant, and the transferred image Unevenness in reflection density, fine periodic patterns, and fine patterns with fine directionality are generated, and accuracy of color reproduction and the like is significantly reduced.

JP-A-59-97140 and JP-A-61-188537,
It discloses a proofing method applicable to both the overlay method and the surprint method. This proofing system prepares a color sheet in which a release layer, a colored photosensitive layer, and a protective film are sequentially laminated on a polyester support, and an image receiving film in which an image receiving layer and a protective film are laminated on a polyester support. The emulsion surface of the color sheet and the halftone negative image are brought into close contact with each other, exposed to form an image, and the unexposed portion is eluted with a mixed solution of sodium carbonate, butyl cellosolve and water. After drying, it can be used as overlay proofing. Since a developer is used, it is difficult to make it continuous.

In the case of use as a surprint proofing, the black image formed on the color sheet on the image receiving film is transferred to the image receiving film under the conditions of a temperature of 110 ° C., a pressure of 2 bar and a speed of 60 cm / min. Then, the image-receiving film is visually or punched to be registered, and a cyan image is transferred. The above operation is repeated in the order of magenta and yellow to obtain a color image. The obtained color image is transferred to an image receptor which is a transfer target. To reduce the gloss of the transferred image, a mattized film is applied to complete the proofing sheet.

In the above method, the original image layer formed on the film on the protective film side of the color sheet is laminated so that the original image layer is in contact with the protective film, and exposed. After the exposure, the protective film is peeled off, and the image is formed by pressing it on the image receptor. Therefore, the formed image becomes a reverse image, and therefore it is necessary to transfer it again in order to obtain a normal image. In this case, since a protective film is interposed between the original image layer and the photosensitive layer, light is diffused and it is difficult to obtain an image with high accuracy. In order to obtain a normal image by one transfer, it is necessary to expose the film having the original image layer so that the film side is in contact with the protective film. In this case, since the film having the original image layer and the protective film are interposed between the original image layer and the photosensitive layer, there is a drawback that light diffusion due to exposure becomes large and the image quality is deteriorated.

Simple proofing in which an image forming material having a photosensitive layer is used and transferred by a relief proof printing machine is also well known. That is,
This is a system in which an image receptor is placed on a paper platen of a proof printing machine, an exposed color sheet is held on an impression cylinder, and transferred while rotating the impression cylinder.

In any of the above methods, image exposure and transfer are
The image forming material and the original image are fixed and exposed on a table or the like by using a register pin or the like, and then transferred from the table or the like to a transfer device by hand.

In color proof, images are formed by repeating four colors, and registering and phase matching in the four colors are important for maintaining image quality. Conventionally, most of these registrations are made by a visual or pin type perforated film. It is difficult to say that these methods are sufficiently applicable, especially when it is desired to form a color image in a short time. That is, it is difficult to continuously perform each process such as exposure and transfer. Further, when the transfer to the image receptor is a manual method, the quality of the image formation depends on the experience and intuition of the operator, so that a good image cannot always be obtained.

The applicants of the present application have filed Japanese Patent Application Laid-Open No. 63-164984, Japanese Patent Application No. 63-
In Japanese Patent Application No. 164985 and Japanese Patent Application No. 63-164986, an image forming method capable of forming an image by superimposing a single color or multiple colors by utilizing the difference in the adhesiveness between the exposed portion and the unexposed portion of the photosensitive layer was proposed. .

For example, in the image forming method proposed in Japanese Patent Application No. 63-164985, the protective film is attached to the exposure drum in the order of the image forming material and the original image on the exposure drum side, and the image forming material exposed to the image is used as the exposure drum. Introducing into the nip formed from the impression cylinder and the nip formed by holding the image forming material in the nip formed by the impression cylinder, holding the image forming material in the impression cylinder and peeling off the protective film. Is a method of transferring the image formed on the photosensitive layer to an image receptor.

According to the method proposed above, it is possible to provide a prepress proof or a small amount of printed matter which has a texture almost equal to that of the actual printed matter and is excellent in color reproducibility with one transfer, and moreover, the exposure and the transfer can be performed uniformly and easily. A method of forming is provided.

[Problems to be Solved by the Invention] However, even in the above method, in order to smoothly promote the transfer of the image forming material from the exposure cylinder to the impression cylinder, a special means for fixing the image forming material of the exposure cylinder and the impression cylinder is used. There is the problem of having to use things. When an inexpensive material such as an adhesive tape is used as the image forming material fixing means of the impression cylinder, there is a problem that the transfer of the image forming material to the impression cylinder does not always proceed reliably. Further, if the nip between the exposure cylinder and the impression cylinder does not have a proper gap, the image forming material is pushed back at the nip entrance, and there is a problem that kinks, wrinkles, misalignment, etc. are likely to occur.

The present invention solves the above problems and provides an image forming method in which the transfer of the image forming material from the exposure cylinder to the impression cylinder is smoothed. Further, the present invention provides an image forming method capable of continuously and easily producing a prepress proof and the like.

[Means for Solving the Problems] The image forming method of the present invention comprises a support, a photosensitive layer formed on one surface of the support, and a protective film provided on the photosensitive layer side of the support. An image-forming material comprising: an image-forming material consisting of and an image-wise exposed layered image, and a part or all of the unexposed portion transferred to an image receptor, the method comprising: a. Step of laminating and adhering the image forming material and the original image in order of the protective film side to the exposure drum having the attachment means for attaching the material to the exposure drum at the front end, b. The exposure arranged on the outer side in the radial direction of the exposure drum Exposing the image-forming material with a light source for use, c. Peeling the original image, and then attaching a temporary adhesive member to the vicinity of the front end of the image-forming material in the direction of advance or to the impression cylinder, d. Introduce the image forming material into the separated nip E. Pressing the front end of the image forming material in the traveling direction by the impression cylinder, f. Causing the exposure cylinder and impression cylinder to perform at least one forward / backward rotation near at least the front end of the image forming material, And g. A step of rotating the exposure cylinder and the impression cylinder forward to transfer the image-forming material or the image-forming material having no protective film onto the impression cylinder.

As the image forming material, various image forming materials such as a material for a dry method for forming an image by peeling development can be used. A material for a dry method by peeling development is preferable because it can be easily operated and can be continuous.

As the light source for exposure, any light source may be used as long as it can cure the photosensitive layer corresponding to the non-image area such as a UV lamp.

The means for affixing the image forming material to the exposure cylinder is a means for sucking and fixing the material by providing a large number of holes or grooves for vacuum means in the material affixing area of the cylinder, a means for fixing with a double-sided adhesive tape, an electrostatic discharge. Means for fixing with a clamp along the axial direction of the exposure cylinder, means for fixing with a clamp, and gripping claws used in the impression cylinder and intermediate cylinder of a printing machine, as long as the material can be fixed on the surface of the cylinder. Any means can be adopted, but it is necessary that the material or the material without the protective film be separated from the exposure cylinder when a nip pressure is applied between the exposure cylinder and the impression cylinder. . For example, when a clamp is used as the attachment means, a cut may be made in the front part and the rear part of the support in the traveling direction, and only the image forming material having no protective film may be transferred onto the impression cylinder. When a clamp or the like is used as the attachment means, it is preferable to install the means so as to be radially inward of the body surface in order to prevent damage to the body surface. In addition, it is preferable that the attachment means accurately aligns the image forming material on the exposure cylinder and the impression cylinder, and also arranges a pin bar or the like in order to ensure proper registration and phase alignment.

The impression cylinder is preferably installed so as to be freely contactable with the exposure cylinder and to adjust the nip pressure between the impression cylinder and the exposure cylinder.
The impression cylinder is preferably covered with an elastic material such as rubber in order to facilitate transfer of the image formed on the photosensitive layer of the image-forming material held on the impression cylinder to the image receptor.

The temporary adhesive member to be attached to the front end portion of the image forming material in the traveling direction or to the impression cylinder may be any one that can transfer the image forming material to the impression cylinder side by nip pressure load such as adhesive, pressure sensitive adhesive, double-sided adhesive tape. . For example, when both the attachment means of the exposure cylinder and the temporary adhesive member are double-sided adhesive tapes, the type of double-sided adhesive tape is selected so that the adhesive strength is different,
It is necessary to select materials for the protective film and the support, or to perform mold release treatment on the exposure cylinder side of the protective film.

Further, by disposing a plurality of small-diameter rolls in the vicinity of the outer peripheral surface of the exposure cylinder and / or the impression cylinder, the image forming material and / or the image receptor may be brought into close contact with the surface of the cylinder to prevent wrinkles and the like from occurring. Good.

When the image forming material is introduced into the nip composed of the impression cylinder and the exposure cylinder, the nip is separated from each other to prevent the image forming material from being wrinkled or displaced at the entrance of the nip. Then, the nip pressure is applied, but at this time, the rotation of the exposure cylinder and the impression cylinder should be substantially stopped.
It is preferable in terms of easiness of control of the device. The nip pressure is usually 1 kgf / cm to 30 kgf / cm, although it depends on the type of temporary adhesive member.

After applying the nip pressure, the exposure cylinder and impression cylinder are rotated back and forth to ensure transfer of the imaging material to the impression cylinder. The movement width of the forward and backward rotation may be repeated several times in the temporary adhesion region near the front end of the image forming material in the traveling direction, and does not need to cover the entire surface of the image forming material.

When separating the protective film on the impression cylinder surface, make sure that the adhesive force between the photosensitive layer and the protective film is weaker than the adhesive force between the photosensitive layer and the support so that the protective film, the material of the support or the It is preferable to appropriately select the material of the layer. Release treatment may be performed on the surface of the protective film.

A method for transferring an image from an image-forming material having an exposed photosensitive layer held on an impression cylinder to an image receptor may be transfer to an image receptor attached to the exposure cylinder, or contact with the impression cylinder. A free transfer cylinder may be separately provided, and the image may be transferred to the image receptor attached to the transfer cylinder.

It is preferable to provide a heating means in the image-receiving member-attaching region of the exposure cylinder or the transfer cylinder so that the image-receiving member can be heated to an appropriate temperature. This is for smoothing the transfer of the exposed photosensitive layer to the image receptor, improving the transfer speed, and improving the precision of reproducing fine images. The temperature of the body surface in the image receiving area is 50 to 150 ° C., preferably 60.
It is about 110 ℃.

The image receptor used in the present invention includes art paper, coated paper,
Any suitable base material such as high-quality paper or film can be selected.

The original image used in the present invention is an image obtained by fixing light-shielding paper to a film (image mask) prepared for a single color or a transparent polyethylene terephthalate film having a function of color coding when a monocolor prepress proof or a printed matter is obtained. It may be a mask, which is a color-separated image mask when obtaining a multicolored color proof or printed matter.

The image-forming material used in the present invention usually comprises a support and a photosensitive layer formed on one surface of the support.

As the support, a material which is stable to heat, chemicals, light and the like and which transmits actinic rays is preferable. For example, cellulose acetate, polystyrene, polyvinyl chloride,
The film or sheet is made of polyethylene terephthalate, polycarbonate, polyimide, polypropylene or the like. In particular, a polyethylene terephthalate film or sheet is preferable because it is excellent in transparency, heat stability and dimensional stability.

These supports may be used as they are, or may be subjected to release treatment with an appropriate oil-repellent substance. Examples of the oil repellent substance include silicon resin and fluorine resin.

The photosensitive layer is composed of (a) a photopolymerizable compound and a colorant, (b) a photopolymerizable compound, a thermoplastic resin and a colorant, and further contains a photopolymerization initiator, a thermal polymerization inhibitor and the like. You may use together.

As the photopolymerizable compound, at least one selected from monomers, oligomers and prepolymers is used.
A compound capable of plasticizing a thermoplastic resin at room temperature is preferable.

As the thermoplastic resin (organic polymer binder), a polymer which is thermoplastic and has no compatibility with the photopolymerizable compound and which does not have photopolymerizability can be used.

As the dye and / or pigment contained in the photosensitive layer, those known in the related art can be used. In general,
Dyes and pigments having hues of yellow, magenta, cyan, and black are desirable, and in addition, metal powder, white pigment, fluorescent pigment, and the like can be used. For color proof, yellow,
There are red, indigo, and black ink, and pigments or dyes matching these hues can be selected and used.

The film thickness of the photosensitive layer may be about 0.5 to 5 μm, and an appropriate coating amount varies depending on the dye and / or pigment contained, but 0.5 to 10 g / m ² is suitable.

Examples of the protective film used in the present invention include polyethylene film, polyethylene terephthalate film, and acetate film. When the protective film is a polyethylene film, the releasing property of the polyethylene film itself may be used, or a releasing agent such as a fluorine resin or a silicone resin may be applied.

Embodiments of the present invention will be described below with reference to the drawings.

1 to 4 are diagrams showing the image forming operation of the present invention including an exposure light source, an exposure cylinder and an impression cylinder.

As shown in FIG. 1, the UV lamp 1 is arranged on the outer side of the exposure cylinder 3 in the radial direction, and on the exposure cylinder, the image forming material 5 and the suction means 11 for attaching the original image 9 and the adhesive tape for attaching the image receptor. Provide 13. The suction means 11 provided in the vicinity of the front and rear ends of the image forming material divides the suction regions into groups so that an original image slightly larger than the image forming material can be sucked, and when the original image is separated, Allow the suction to be released. Further, the suction regions can be divided into groups, so that various sizes of the image forming material and the original image can be appropriately dealt with, which is convenient. The suction means 11 attaches the image forming material and the original image to the exposure cylinder with the original image as the outside. Further, the image receptor 15 is attached to the exposure cylinder by the adhesive tape 13. After the image exposure, the original image is peeled off, the adhesive tape 13 is attached to the vicinity of the front end portion and the rear end portion in the image forming material traveling direction, and then the exposure cylinder is rotated.
The image forming material is introduced into the nip between the exposure drum 3 and the impression drum 17.

As shown in FIG. 2, the rotation of the exposure cylinder is stopped and the image forming material is pressed by the impression cylinder.

As shown in FIG. 3, the exposure cylinder and the impression cylinder are rotated forward and backward so that the image forming material adheres well to the impression cylinder.

Then, as shown in FIG. 4, the exposure cylinder and the impression cylinder are rotated forward so that the image forming material is transferred onto the impression cylinder. The suction of the suction means may be released during this forward rotation.

Peel off the protective film of the image forming material that was transferred to the impression cylinder,
Then, the impression cylinder and the exposure cylinder are rotated, and the image formed on the photosensitive layer is pressure-transferred onto the image receptor 15 attached to the exposure cylinder.

It is preferable that a heating means (not shown) is provided in the image receptor attachment area of the exposure cylinder. The exposure cylinder is preferably rotated further and the transferred image is post-exposed by a UV lamp.

[Effect of the Invention] According to the present invention, a color proof having a texture equivalent to that of an actual printed matter can be provided easily, quickly, and stably, particularly in a surprint method using a printing paper.

The present invention can be applied not only to the overlay method but also to printing a small number of copies up to about several hundreds.

According to the present invention, the quality of the transferred image obtained is good, a normal image can be obtained by one transfer, exposure-transfer (further, post-exposure) can be continuously carried out, and registration is easy. Therefore, there is a remarkable effect that a stable image can be obtained without depending on the experience and intuition of an expert.

In the image forming material composed of support / photosensitive layer / protective film, the thickness of the protective film is thicker than that of the support, and the light transmittance is often poor.

According to the present invention, since light is exposed from the support side, light is less diffused and scattered, and therefore a good prepress proof or printed matter can be provided.

According to the present invention, the nip is preliminarily separated from the exposure cylinder and the impression cylinder, and the image forming material is introduced into the nip, so that the kink of the image forming material at the entrance of the nip, wrinkles, and positional deviation do not occur, It can provide clear color proof or printed matter without misregistration.

According to the present invention, the exposure cylinder and the impression cylinder are rotated back and forth after pressurizing the image forming material to ensure the transfer of the image forming material onto the impression cylinder. Therefore, a clear color proof is obtained regardless of the skill level of the operator. Or printed matter can be provided.

[Brief description of drawings]

1 to 4 are diagrams showing an image forming operation of the present invention. DESCRIPTION OF SYMBOLS 1 ... UV lamp, 3 ... Exposure cylinder 5 ... Image forming material, 9 ... Original image 11 ... Suction means, 13 ... Adhesive tape 15 ... Image receptor, 17 ... Impression cylinder

Claims (1)

[Claims] 1. An image forming material comprising a support, a photosensitive layer formed on one surface of the support, and a protective film provided on the photosensitive layer side of the support is laminated with an original image. Image-exposing, and transferring a part or all of the unexposed area to the image receptor, the method comprising: a. Attaching the image-forming material to the exposure cylinder at least at the front end in the traveling direction. A step of laminating and adhering the image forming material and the original image in this order on the exposure cylinder having a means with the protective film side as the inner side; b. Exposing the image forming material by an exposure light source arranged radially outside the exposure cylinder, c . The step of peeling off the original image and then attaching the temporary adhesive member to the vicinity of the front end portion of the image forming material in the traveling direction or to the impression cylinder, d. The image forming material is introduced into the separated nip formed from the impression cylinder and the exposure cylinder Step, e. Progress of the image forming material by the impression cylinder Direction front end, f. At least one forward and backward rotation of the exposure cylinder and impression cylinder near at least the front end of the imaging material, and g. Forward rotation of the exposure cylinder and impression cylinder And a step of transferring the image forming material or the image forming material having no protective film thereon.