JPH0693119B2 - Photosensitive sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a positive photosensitive sheet. More specifically, it relates to a positive-type photosensitive sheet used for producing a positive-type image-forming material by coating on a support, and is mainly used as a printing plate-making material, a double-drawing material and the like.

[Problems to be Solved by Prior Art and Invention]

The photosensitive composition used in the conventional positive image-forming material includes (1) a composition comprising an o-quinonediazide compound and a composition comprising an o-quinonediazide compound and an alkali-soluble resin such as a novolak resin, and -It utilizes a phenomenon that a quinonediazide compound is converted into an alkali-soluble substance by light irradiation (see, for example, JP-A-50-12580).
6, can be found in JP-A-61-5251).

(2) Composition comprising a photosensitive diazonium salt and a water-soluble resin A composition comprising a photosensitive diazonium salt and a water-soluble resin such as polyvinyl alcohol and diacetone acrylamide-acrylamide copolymer, which comprises a photosensitive diazonium salt and a water-soluble resin. This utilizes the phenomenon that a water-soluble resin undergoes a coupling reaction in an alkaline atmosphere (for example, JP-A-56-101141, JP-A-56-101144 and JP-A-57).
-72140, JP-A-57-191632, etc.).

However, these conventional photosensitive compositions have the following problems. That is, in both (1) and (2), since an alkaline solution is used for development, there is a risk of causing safety problems in development work and pollution problems in wastewater treatment. Further, in the case of (2), development processing with ammonia vapor is possible, but a strong ammonia odor remarkably deteriorates the working environment.

In the image formed in (1), the color of the o-quinonediazide compound or its decomposition product remains, and in (2), there is a specific color development due to the coupling reaction. Therefore, (1),
(2) Even if a colorant is added, it is difficult to obtain a colored image of any color.

[Object of the Invention]

An object of the present invention is to provide a positive-type photosensitive sheet for producing a positive-type image-forming material, which is developable with water or warm water and is free from coloring due to a light-sensitive component or its decomposed product and coloration caused by an image-forming reaction. .

[Means for solving problems]

As a result of intensive studies on the novel positive photosensitive composition that can be developed with water or warm water, the present inventors have found that a water-soluble photocrosslinking agent conventionally used for negative photosensitive compositions (for example, JP-B-4428725). No. 1), a positive type photosensitive sheet can be obtained. That is,
A synthetic resin emulsion composed of a water-soluble photocrosslinking agent and a water-soluble resin, an acrylic synthetic resin emulsion, or a copolymer or a mixture of an acrylic synthetic resin and another synthetic resin (hereinafter simply referred to as an acrylic synthetic resin emulsion)
It has been discovered that a positive image is obtained by exposing a photosensitive layer of a composition composed of the above to a support on a positive image original, immersing it in water, and rubbing it with a sponge.
In addition, the obtained image had no coloring due to the light-sensitive component and no color formation due to the image forming reaction. The mechanism of this phenomenon is considered as follows.

Exposed Area The water-soluble photocrosslinking agent and the water-soluble resin in the photosensitive layer are photocrosslinked by being exposed to actinic rays. When soaked in water, the photocrosslinking component easily swells and softens the photosensitive layer in this portion. It also reduces the adhesion to the support. Therefore, this portion is easily removed from the support by rubbing with a sponge or the like.

Unexposed area When immersed in water, most of the water-soluble photo-crosslinking agent and water-soluble resin in the photosensitive layer elute, but there is no change such as swelling or softening in the photosensitive layer and adhesion to the support does not change. Therefore, even if it is rubbed with a sponge, it is not removed from the support. Further, most of the water-soluble photocrosslinking agent in the photosensitive layer is eluted, and the remaining photosensitive layer is colorless.

The present invention relates to a positive type photosensitive sheet utilizing the above phenomenon.

Hereinafter, the present invention will be described in more detail.

As the water-soluble photocrosslinking agent used in the photosensitive layer of the photosensitive sheet of the present invention, a water-soluble azide compound, a diazonium salt, a tetrazonium salt, or other known organic photosensitive substances can be used. Here are just a few of them.

Water-soluble azide compound 4,4'-diazidostilbene-2,2'-sodium disulfonate 4-azido-4-azidobenzalacetophenone-2-
Sodium sulfonate 4,4'-Diazidostilbene-α Sodium carboxylic acid Di- (4-azido-2'-hydroxybenzal) acetone-2-Sodium sulfonate 4-Azidobenzal acetophenone-2-Sodium sulfonate diazo Resin Paradiazodiphenylamine and formaldehyde condensate 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 Diphenyl methane-4,4'-bisdiazonium chloride, zinc chloride double salt The water-soluble resin used in the photosensitive layer of the photosensitive sheet of the present invention is Acrylamide, polyvinylpyrrolidone,
Polyvinyl alcohol, polyvinyl alcohol graft polymerized, water-soluble polyvinyl butyral, glue, casein, gelatin, gum arabic, egg white, gums, alginic acid, polyethylene oxide, polyacrylic acid and its salts, polymethacryl Many examples include acids and salts thereof, mixtures thereof, and mixtures of these with cellulose derivatives such as polyvinyl alcohol, carboxymethyl cellulose and hydroxyethyl cellulose.

Furthermore, if necessary, conventionally known water-dispersible color pigments, water-soluble dyes, leveling agents, stabilizers, matting agents, etc. can be added to the photosensitive layer of the photosensitive sheet of the present invention.

The photosensitive sheet of the present invention comprises the above-mentioned water-soluble photocrosslinking agent, water-soluble resin, and acrylic synthetic resin emulsion, and the solid component mixing ratio of the water-soluble resin and acrylic synthetic resin emulsion is 1:99 to 80:20. And more preferably 5:95 to 40:60. When the amount of the water-soluble resin is too much, the water resistance of the image is lowered and the image falls off during development. If the synthetic resin emulsion is too much, the developability will decrease. No image can be obtained if it is significantly outside the above range. The solid content of the water-soluble photocrosslinking agent and the sum of the water-soluble resin and the acrylic synthetic resin emulsion is 98: 2 to 70:30, more preferably 96: 4 to 8
It is 0:20. If the water-soluble photocrosslinking agent is less than this,
The sensitivity and the image quality are remarkably deteriorated, and conversely, when the amount is too large, the image quality is deteriorated. No image can be obtained if it is significantly outside the above range. If a colorant is added, the content of the water-soluble photocrosslinking agent, the water-soluble resin, and the solid content of the acrylic synthetic resin emulsion is 20% or less for the color pigment and 10% for the water-soluble dye.
% Or less is preferable. The above-mentioned components constituting these photosensitive sheets are prepared by dissolving and dispersing in water, a water / alcohol mixed liquid or the like.

The photosensitive layer coating liquid of the photosensitive sheet of the present invention thus prepared is applied on a support to prepare a positive type image forming material. As the support, polyethylene terephthalate,
Examples thereof include plastic films such as polypropylene, polyethylene, polyvinyl chloride, polystyrene, polycarbonate, and triacetate, glass plates, and paper waterproofed by laminating polyethylene or polypropylene on both sides. Also, pencil, ink,
A sand mat film produced by a sand blast method for imparting writability with a ball-point pen or the like, a plastic film having a drawing aptitude such as an etching mat film etched with an alkali, and an opacified film in which a white pigment is kneaded can also be used. Further, the photosensitive layer may be directly coated on the support, but in order to improve the adhesiveness, corona discharge treatment, coating of a primer treatment agent in advance,
Alternatively, it is desirable to perform an adhesive process using these together. As the primer treatment agent, for example, phenol resin,
Polyester resin, urethane resin, vinylidene chloride-vinyl acetate copolymer, vinylidene chloride-acrylonitrile copolymer, etc. and mixtures thereof are used,
A coating thickness of 0.1 to 2.0 μm is preferred.

The coating on the support may be carried out by any method such as spin coating, roll coating, bar coating, brush coating and the like. The coating amount is such that the thickness of the coating film after drying is about 1 to 5 μm, preferably about 2
It is about μm. The thinner the coating film, the better the resolution of the image. After coating, it is usually dried by hot air, but air drying may be used.

The positive image-forming material formed using the photosensitive sheet of the present invention forms an image by the following steps.

(1) Exposure An original is placed on the surface of the prepared image forming material coated with the photosensitive composition, and an active ray such as various mercury lamps, carbon arc lamps, xenon lamps, metal halide lamps, and ultraviolet fluorescent lamps is irradiated on the original.

(2) Immersion in water or warm water The exposed image forming material is immersed in water or warm water to swell the non-image area. The water temperature at this time is not particularly limited, but a higher temperature can accelerate the swelling of the non-image area and shorten the immersion time. The water temperature depends on the selection of each component constituting the photosensitive composition, but it is 5 to 50 in consideration of workability.
A water temperature of ℃, more preferably 25-45 ℃ is selected. The immersion time is determined by the time required for the non-image area to swell sufficiently.

(3) Removal of non-image area, dry Non-image area is removed by rubbing the photosensitive surface of the image forming material soaked with a sponge containing water. Then dry.

The image forming mechanism of the photosensitive sheet of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows the structure of the photosensitive film.

Here, the photosensitive film has a photosensitive layer formed on a support.

The photosensitive layer comprises a synthetic resin emulsion, a water-soluble polymer, a water-soluble photocrosslinking agent, and optionally a coloring agent,
The colorant is omitted here.

The 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. Further, the gap of the synthetic resin emulsion is filled with a mixture of a water-soluble polymer and a water-soluble photocrosslinking agent.

FIG. 2 shows a state in which the photosensitive film is exposed.

The actinic radiation passes through the transparent areas of the document to expose the image. At this time, the exposed portion of the water-soluble polymer and the water-soluble photocrosslinking agent are photocrosslinked by a photocrosslinking reaction. By this reaction, the photo-crosslinked product of the water-soluble photo-crosslinking agent and the water-soluble photo-crosslinking agent becomes water-insoluble, but easily swells with water or warm water. Alternatively, it shows a state of being immersed in warm water.

By dipping the photosensitive film in water or warm water, the photo-crosslinked product of the [exposed portion] water-soluble polymer and water-soluble photo-crosslinking agent is water-insoluble, so it will not elute in water or warm water. Swells by absorbing warm water. The partial fusion between the synthetic resin emulsions is separated by the swelling of the photo-crosslinked product of the water-soluble polymer and the water-soluble photo-crosslinking agent, and the synthetic resin emulsion is also peeled from the support or is easily peeled. It becomes a state.

[Unexposed Area] Since both the unreacted water-soluble polymer and the water-soluble photocrosslinking agent in the gap 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 phenomenon that partial fusion between the synthetic resin emulsions is broken or the synthetic resin emulsion is peeled off from the support does not occur.

FIG. 4 shows the formed image after development.

The development is a work of scraping off the swelled exposed portion with a sponge, a brush or the like.

Here, in the exposed part, the partial fusion between the synthetic resin emulsions is separated, and since the synthetic resin emulsion is also separated from the support, it can be easily removed from the support by rubbing with a sponge, a brush or the like. However, in the unexposed portion, the partial fusion between the synthetic resin emulsions is not broken, and since the synthetic resin emulsion is not peeled off from the support, it is not removed from the support even if it is rubbed with a sponge or a brush. Thus, the photosensitive film using the photosensitive sheet of the present invention in the photosensitive layer exhibits a positive action in which the unexposed portion becomes an image.

[Example] Example 1 Liquid A (photosensitive liquid) However, the carbon black dispersion was obtained by dispersing for 3 hours with an ink kneader with the following composition.

Liquid A was applied to one surface of a polyethylene terephthalate film having a thickness of 75 μm by a spin coater and dried with warm air at 90 ° C. for 90 seconds to form a photosensitive layer having a thickness of 2 μm. Then, a positive original 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. After dipping this product in warm water at 15 ° C for 60 seconds to swell the non-image area sufficiently, the photosensitive surface was rubbed with a sponge containing water to remove the non-image area, and a black sharp optical density of 1.20 A relief positive image is obtained.

[Brief description of drawings]

Each of the drawings is an explanatory view showing the mechanism of image formation of the present invention, FIG. 1 shows a photosensitive film, FIG. 2 is an explanatory view at the time of exposure, and FIG. 3 is an explanatory view at the time of immersion in hot water or water. ,
FIG. 4 is an explanatory diagram during development.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location G03F 7/38 511 7124-2H

Claims (4)

[Claims] 1. A water-soluble resin that forms a swellable film after a photo-crosslinking reaction, a water-soluble photo-crosslinking agent, and an acrylic synthetic resin emulsion or a copolymer or mixture of an acrylic synthetic resin and another synthetic resin. A photosensitive resin layer having a thickness of 5 μm or less, which comprises a synthetic resin emulsion and, if necessary, a colorant, is formed on a support sheet,
A positive photosensitive sheet that can be developed only with water or warm water. 2. The photosensitive sheet according to claim 1, wherein the solid component ratio of the water-soluble resin to the synthetic resin emulsion is in the range of 5:95 to 40:60. 3. The sum of the water-soluble resin and the synthetic resin emulsion, and the solid content ratio of the water-soluble photocrosslinking agent is 98: 2 to 70:30. The photosensitive sheet according to the item. 4. The water-soluble photocrosslinking agent is any one of a water-soluble diazide compound, a diazo resin, and a tetrazonium salt, and any one of claims 1 to 3 is described. Photosensitive sheet.