JPH0551897B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a positive-positive image forming method mainly used for printing plate materials, reproduction materials, etc. The present invention relates to a method for forming images that are free from coloration caused by photocrosslinking agents. [Prior Art] Conventional positive-positive photosensitive compositions and image forming methods using the same include: (1) Compositions comprising o-quinonediazide compounds/
Alkaline development, organic solvent development system. It is a composition consisting of an o-quinonediazide compound and an alkali-soluble resin such as a novolac resin or an organic solvent-soluble resin. Those that form images by dissolution development or organic solvent dissolution development (for example, JP-A-50-125806,
(See Japanese Patent Application Laid-Open No. 61-5251, etc.). (2) Compositions consisting of photosensitive diazonium salts and water-soluble resins/alkaline development, ammonia development systems. A composition consisting of a photosensitive diazonium salt and a water-soluble resin such as polyvinyl alcohol, diacetone acrylamide-acrylamide copolymer,
Utilizing the phenomenon that a photosensitive diazonium salt and a water-soluble resin undergo a coupling reaction in an alkaline atmosphere and become water-insolubilized, an image is formed by scraping off the non-image area after immersion in an alkaline solution or after coming into contact with ammonia vapor. things (for example, JP-A-56-101141
No., JP-A-56-101144, JP-A-57-72140,
(See Japanese Patent Application Laid-Open No. 57-191632, etc.). However, these conventional image forming methods have the following problems. That is, since (1) uses an alkaline solution or an organic solvent, and (2) uses an alkaline solution, there is a risk of safety problems in developing operations and pollution problems in wastewater treatment. In addition, (2) can be developed using ammonia vapor, but the strong ammonia odor significantly worsens the working environment. Furthermore
The image formed in (1) retains the color of the o-quinonediazide compound or its decomposed product, and (2) has a unique color development due to a coupling reaction. For this reason,
In both (1) and (2), it is difficult to obtain a colored image in any color even if a coloring agent is added. [Problems to be Solved by the Invention] The purpose of the present invention is to form an image by hot water treatment without using any chemicals such as alkalis or organic solvents, and to avoid coloring and image forming reactions caused by photosensitive components or their decomposition products. An object of the present invention is to provide a positive-positive image forming method that does not cause color development. [Means for Solving the Problems] The gist of the present invention is to apply a composition comprising a water-soluble photocrosslinking agent, a water-soluble resin, a synthetic resin emulsion, and, if necessary, a coloring agent, onto a substrate to expose it to light. By forming a layer on the photosensitive layer, exposing the original to actinic rays, and then immersing the original in hot water at 30 to 60°C for 3 seconds or more, the exposed areas are sufficiently swollen and softened by the warm water, and the unexposed areas become water-soluble. Most of the photocrosslinking agent is eluted into hot water, and then the exposed areas that have swelled and softened in the hot water are rubbed off to form an image that is free from coloration caused by the water-soluble photocrosslinking agent, without using any developing chemicals other than water. The present invention relates to a positive-positive image forming method characterized by: [Function] The present inventors conducted extensive research into a new positive-positive image forming method that allows image formation without using any chemicals such as alkali or organic solvents, and as a result, the present inventors found that conventional negative-tone photosensitive compositions We have discovered a phenomenon in which a positive-working photosensitive composition can be obtained using a previously used water-soluble photocrosslinking agent (for example, the one shown in Japanese Patent Publication No. 44-28725). That is, a phenomenon in which a photosensitive layer formed on a support with a composition consisting of a water-soluble photocrosslinking agent, a water-soluble resin, and a synthetic resin emulsion is exposed to light using a positive original, immersed in warm water, and rubbed with a sponge to obtain a positive image. discovered. Furthermore, the resulting image is characterized by almost no coloring due to photosensitive components or coloring due to image forming reactions. The mechanism of this phenomenon is thought to be as follows. Γ Exposed area: Exposed to actinic rays to crosslink the water-soluble photocrosslinking agent and water-soluble resin in the photosensitive layer. When immersed in warm water, this photocrosslinking component easily swells and softens the photosensitive layer in this area. It also reduces the adhesion to the support. Therefore, this portion can be easily removed from the support by rubbing with a sponge or the like. ΓUnexposed area When immersed in warm water, most of the water-soluble photocrosslinking agent and water-soluble resin in the photosensitive layer are eluted, but there is no change in the photosensitive layer such as swelling or softening, and the adhesion to the support is maintained. remains the same. Therefore, it cannot be removed from the support even if it is rubbed with a sponge. Further, since most of the water-soluble photocrosslinking agent in the photosensitive layer is eluted, the remaining photosensitive layer is colorless. The present invention provides a positive-positive image forming method that utilizes the above phenomenon. As the water-soluble photocrosslinking agent of the photosensitive composition used in the image forming method of the present invention, water-soluble azide compounds, diazonium salts, tetrazonium salts, and other known organic photosensitive substances can be used.
Here are some of the types: Γ Water-soluble azide compound 4,4-diazidostilbene-2,2'-sodium disulfonate 4'-azido-4-azidobenzalacetophenone-2-sodium sulfonate 4,4'-diazidostilbene-α -Sodium carboxylate di-(4-azido-2'-hydroxybenzal)
Sodium acetone-2-sulfonate 4-azidobenzalacetophenone-2-sodium sulfonate Γ diazo resin Condensate of paradiazodiphenylamine and formaldehyde Γ tetrazonium salt Diphenyl-4,4'-bisdiazonium chloride/zinc chloride Double salt 3,3'-dimethyldiphenyl-4,4'-bisdiazonium chloride/zinc chloride double salt 3,3'-dimethoxydimethyl-4,4'-bisdiazonium chloride/zinc chloride double salt diphenylamine- 4,4'-bisdiazonium chloride/zinc chloride double salt Diphenylmethane-4,4'-bisdiazonium chloride/zinc chloride double salt As a water-soluble resin for the photosensitive composition used in the image forming method of the present invention Polyacrylamide, polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl alcohol grafted with vinyl monomer, water-soluble polyvinyl butyral, glue, casein, gelatin, gum arabic, egg white, gums, alginic acids, polyethylene oxide, polyacrylic Examples include acids and salts thereof, polymethacrylic acid and salts thereof, mixtures thereof, and mixtures of these with cellulose derivatives such as polyvinyl alcohol, carboxymethyl cellulose, and hydroxyethyl cellulose. The synthetic resin emulsion of the photosensitive composition used in the image forming method of the present invention includes polyacrylic ester, ethylene-vinyl acetate copolymer,
Numerous examples include polyvinylidene chloride, vinyl acetate, polyvinyl chloride, polyester, copolymers or mixtures thereof, and the like. Furthermore, conventionally known water-dispersible coloring pigments, water-soluble dyes, leveling agents, stabilizers, matting agents, etc. may be added to the photosensitive composition used in the image forming method of the present invention, if necessary. be able to. The photosensitive composition used in the image forming method of the present invention is composed of the above-mentioned water-soluble photocrosslinking agent, water-soluble resin, and synthetic resin emulsion, and the solid proportion of the water-soluble resin and the synthetic resin emulsion is 1:99. ~80:20, more preferably 5:95~40:60. If there is too much water-soluble resin, the water resistance of the image will decrease and the image will fall off during development. If the amount of synthetic resin emulsion is too large, developability will deteriorate. If the value is significantly outside the above range, no image can be obtained. The solid ratio of the water-soluble resin and the synthetic resin emulsion to the water-soluble crosslinking agent is preferably 98:2 to 70:30, more preferably 96:4 to 80:20. If the amount of the water-soluble photocrosslinking agent is less than this, the sensitivity and image quality will be significantly lowered, and if it is too much, the image quality will be lowered. If the value is significantly outside the above range, no image can be obtained.
When a coloring agent is further added, it is preferable that the amount of the colored pigment is 20% or less and the amount of the water-soluble dye is 10% or less based on the total solid content of the water-soluble crosslinking agent, water-soluble resin, and synthetic resin emulsion. The above components constituting these photosensitive compositions are prepared by being dissolved or dispersed in water or a water/alcohol mixture. The photosensitive composition prepared in this manner and utilized in the image forming method of the present invention is coated onto a support to produce a positive-positive type image forming material. Examples of the support include plastic films such as polyethylene terephthalate, polypropylene, polyethylene, polyvinyl chloride, polystyrene, polycarbonate, and triacetate, glass plates, and paper made waterproof by laminating polyethylene or polypropylene on both sides. In addition, in order to provide writing properties with pencil, ink, ballpoint pen, etc. on one or both sides, we used plastic films that were made suitable for drafting, such as sandblasted sand matte films, etched matte films that were etched with alkali, and white pigments. Opalescent processed films can also be used. Also,
Although the photosensitive layer may be applied directly to the support, in order to improve adhesion, it is desirable to perform corona discharge treatment, application of a primer treatment agent, or adhesion processing using a combination of these in advance. As the primer treatment agent, phenol resin, polyester resin, urethane resin, vinylidene chloride-vinyl acetate copolymer, vinylidene chloride-acrylonitrile copolymer, and mixtures thereof are used, and a coating film of 0.1 to 2.0 μm is formed on the support. Thickness is preferred. Coating onto the support may be performed by any method such as a spin coating machine, roll coating, bar coating, or brush coating. The coating amount is approximately 1 to 5 μm thick after drying.
m, preferably about 2 μm. The thinner the coating film, the better the resolution of the image. After application, it is usually dried with hot air at a temperature of about 90°C or less, but air drying may also be used. In the image forming method of the present invention, a positive-positive image forming material prepared using the photosensitive composition is processed through the following steps. (1) Exposure A manuscript is placed over the photosensitive composition-coated surface of the prepared image-forming material, and is irradiated with active light from various mercury lamps, carbon arc lamps, xenon lamps, metal halide lamps, ultraviolet fluorescent lamps, etc. (2) Warm water immersion The exposed image forming material is immersed in hot water, the exposed non-image areas are swollen and softened, and the water-soluble photocrosslinking agent in the unexposed image areas is eluted into the warm water. The temperature of the hot water at this time is preferably 30° C. to 60° C. If the water is lower than this, the exposed areas will not swell or soften sufficiently, making it difficult to reproduce fine lines, small halftone dots, etc. In addition, water at a higher temperature than this softens the image area, so
The quality of the resulting image may deteriorate or the non-image areas may become smeared due to adhesion of the components of the photosensitive composition to the substrate. Furthermore, when high temperature water is used, its steam creates a poor working environment. The immersion time in hot water is determined by the time for the non-image area to swell sufficiently and the time for the water-soluble photocrosslinking agent in the image area to dissolve into the warm water, but it is 3 seconds or more, more preferably 10 seconds or more. is necessary. (3) Removal of non-image areas and drying The photosensitive surface of the image forming material soaked in warm water is rubbed with a sponge, brush, etc. to remove non-image areas. This operation may be carried out under any conditions, such as under warm water or room temperature water, under running water, or in a vat without water. Then dry. The mechanism of image formation in the image forming method of the present invention will be explained in detail below with reference to the drawings. FIG. 1 shows the structure of a photosensitive film used in the image forming method of the present invention. Here, the photosensitive film is one in which a photosensitive layer is formed on a support. The photosensitive layer consists of a synthetic resin emulsion, a water-soluble resin, a water-soluble photocrosslinking agent, and, if necessary, a colorant, but the colorant is omitted here. A synthetic resin emulsion is uniformly dispersed in the photosensitive layer, and the synthetic resin emulsions are partially fused to each other and also adhered to the support. Furthermore, the space between the synthetic resin emulsion is filled with a mixture of a water-soluble resin and a water-soluble photocrosslinking agent. FIG. 2 shows the photosensitive film being exposed. The actinic light passes through the transparent portion of the document and exposes the image. At this time, the water-soluble resin and the water-soluble photocrosslinking agent in the exposed portion are photocrosslinked by a photocrosslinking reaction. A photocrosslinked product of a water-soluble resin and a water-soluble photocrosslinking agent photocrosslinked by this reaction becomes water-insoluble, but is easily swollen by water or hot water. FIG. 3 shows the exposed photosensitive film immersed in water or hot water. When a photosensitive film is immersed in water or hot water, the photocrosslinked product of the water-soluble resin and water-soluble photocrosslinking agent (exposed area) is water-insoluble and will not dissolve in water or hot water. absorbs and swells. Due to the swelling of the network-structured photocrosslinked product of the water-soluble resin and the water-soluble photocrosslinking agent caused by the light, the layer in the exposed area is lifted, and the partial fusion between the synthetic resin emulsions is separated, and the synthetic resin emulsion is also peeled off from the support. [Unexposed Area] Since both the unreacted water-soluble resin and water-soluble photocrosslinking agent present between the ends of the synthetic resin emulsion are water-soluble, most of them are eluted from the photosensitive layer into water or warm water. At this time, the partial fusion between the synthetic resin emulsions is broken. The phenomenon that the synthetic resin emulsion is peeled off from the support does not occur. FIG. 4 shows the image formed after development. Developing is a process of rubbing off the swollen exposed areas with a sponge, brush, etc. Here, in the exposed area, the synthetic resin emulsion is partially fused to each other, and since the synthetic resin emulsion has also been peeled off from the support, it can be easily removed from the support by rubbing with a sponge, brush, etc. However, in the unexposed areas, the partial fusion between the synthetic resin emulsions is not destroyed;
Since the synthetic resin emulsion is not peeled off from the support, it will not be removed from the support even if rubbed with a sponge, brush, etc. Thus, a photosensitive film using the photosensitive composition of the present invention in its photosensitive layer exhibits a positive effect in which unexposed areas form images. [Example] Examples will be given below, but the present invention is not limited thereto. Example 1 Liquid A (photosensitive liquid)

[Table] However, the carbon black dispersion liquid was obtained by dispersing the following formulation in an ink mixer for 3 hours. Carbon black 60 parts by weight Metrose 60SH4000 10 parts by weight (hydroxypropyl methyl cellulose, manufactured by Shin-Etsu Chemical Co., Ltd.) Nonionic activator 1 part by weight (polyethylene glycol alkyl phenyl ether mixture) Water 229 parts by weight Polyethylene terephthalate with a thickness of 75 μm Solution A was coated on one side of the film using a spin coating machine and dried for 90 seconds with hot air at 90°C to form a photosensitive layer with a thickness of 2 μm. Next, a halftone positive original for printing was brought into close contact with the photosensitive layer, and exposed for 10 seconds from a distance of 1 m using a 2 kW ultra-high pressure mercury lamp. This product was immersed in warm water at 45°C for 60 seconds to sufficiently swell the non-image area, and then the photosensitive surface was rubbed with a sponge to remove the non-image area, resulting in a sharp black relief positive image with an optical density of 1.20. It was done. This image is 0.5 ~
It reproduced 99.5% of halftone dots. Comparative Example 1 The exposed image forming material obtained in Example 1 was heated to 15°C.
After immersing it in water for 60 seconds, the photosensitive surface was rubbed with a sponge to remove the non-image area, and the positive image formed did not have halftone dots that were less than 20% of the original. Comparative Example 2 The exposed image forming material obtained in Example 1 was heated to 45°C.
After immersing it in hot water for 2 seconds, the photosensitive surface was rubbed with a sponge to remove the non-image area, and the positive image formed did not have halftone dots that were less than 10% of the original. Example 2 Liquid B (photosensitive liquid) 4,4'-Diazidostilbene-2,2'-disulfonic acid sodium 0.7 parts by weight PVP K-90 1.0 parts by weight (polyvinylpyrrolidone, manufactured by General Aniline & Film Company) Sumielite 1010 (50% liquid) 10.7 parts by weight (ethylene-vinyl chloride copolymer emulsion,
(manufactured by Sumitomo Chemical Co., Ltd.) Methanol 17.5 parts by weight Water 70.1 parts by weight Similarly to Example 1, Solution B was applied to one side of a 75 μm thick polyethylene terephthalate film and dried to form a 2 μm thick photosensitive layer. Next, it was exposed to light for 4 seconds at a distance of 1 m using a 2kw ultra-high pressure mercury lamp, and heated to 40°C.
After immersing the photosensitive layer in hot water for 10 seconds to sufficiently swell the non-image area, lightly rubbing the photosensitive layer with a sponge soaked in water under running water removes the exposed non-image area and yields a colorless positive relief image. It was done. Comparative Example 3 The exposed image forming material obtained in Example 2 was heated to 40°C.
When the photosensitive layer was immersed in water for 2 seconds and then lightly rubbed with a sponge soaked in water under running water, an image similar to that obtained in Example 2 was obtained, but the image did not contain the water-soluble photocrosslinking agent. Coloring was clearly observed. Example 3 C liquid (photosensitive liquid)

[Table] Solution C was coated on one side of a polyethylene terephthalate film with a thickness of 75 μm using a spin coater, and dried with warm air at 90° C. for 60 seconds to form a photosensitive layer with a thickness of 1.5 μm. Next, a positive original is placed in close contact with the photosensitive layer, and a 2kw
Exposure was performed for 12 seconds from a distance of 1 meter using an ultra-high pressure mercury lamp. This material was immersed in warm water at 35°C for 60 seconds to sufficiently swell the non-image area, and then the photosensitive surface was rubbed with a sponge soaked in water to remove the non-image area, resulting in a black sharp optical density of 0.85. A relief positive image was obtained. Example 4 Solution D (photosensitive liquid) 4,4'-Diazidostilbene-2,2'-sodium disulfonate 0.9 parts by weight PVP K-90 0.8 parts by weight Sumikaflex 830 (50% liquid) 16.4 parts by weight (vinyl acetate) Ethylene-vinyl chloride copolymer emulsion, manufactured by Sumitomo Chemical Co., Ltd.) Carbon black dispersion 5.0 parts by weight Methanol 38.5 parts by weight Water 38.5 parts by weight Apply Solution D to one side of a 75 μm thick polyethylene terephthalate film using a spin coater. It was dried with warm air at 90° C. for 60 seconds to form a photosensitive layer with a thickness of 1.5 μm. Next, a plate control wedge UGRA PCW82 (manufactured by Mika Denshi Co., Ltd.) was attached to the photosensitive layer, and a 1 m
A 12 second exposure was made from a distance of . this thing
After immersing the non-image area in warm water at 40℃ for 30 seconds to sufficiently swell the non-image area, the photosensitive surface was rubbed with a sponge soaked in water under running water to remove the non-image area. A relief positive image was obtained. The image formed reproduced 6μ fine lines and 0.5 to 99.5% halftone dots. Comparative Example 4 The exposed image forming material obtained in Example 4 was heated to 20°C.
After immersing the photosensitive surface in water for 30 seconds, the non-image area was removed by rubbing the photosensitive surface with a sponge soaked in water under running water, but no halftone image of 30% or less could be formed.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the structure of a photosensitive film used in the image forming method of the present invention. FIG. 2 is an explanatory diagram showing a state in which a photosensitive film is exposed. FIG. 3 is an explanatory diagram showing a state in which an exposed photosensitive film is immersed in water or warm water.
FIG. 4 is an explanatory diagram showing the image formed after development. In the drawing, 〓〓...Synthetic resin emulsion, 〓〓〓
...Mixture of water-soluble resin and water-soluble photocrosslinking agent,〓〓〓
...Photo-crosslinked product (exposed area) of water-soluble resin and water-soluble photo-crosslinking agent,〓〓〓...Swelling part of photo-crosslinked product of water-soluble resin and water-soluble photo-crosslinker,〓〓〓...All of the synthetic resin emulsion A portion of the water-soluble resin and water-soluble photocrosslinking agent remains (unexposed area).

Claims (1)

[Claims] 1. A photosensitive layer was formed on a base material using a composition consisting of a water-soluble photocrosslinking agent, a water-soluble resin, a synthetic resin emulsion, and a coloring agent if necessary, and a document was exposed to actinic rays on the photosensitive layer. Afterwards, by immersing the exposed area in hot water of 30 to 60°C for 3 seconds or more, the exposed area is sufficiently swollen and softened by the hot water, and most of the water-soluble photocrosslinking agent in the unexposed area is eluted into the warm water, and then the exposed area is immersed in the warm water. A positive-positive image forming method characterized by forming an image free from coloring caused by a water-soluble photocrosslinking agent without using any developing chemicals other than water by scraping off swollen and softened exposed areas.