JPH054663B2 - - Google Patents

Description

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

[Problems to be solved by conventional technology and invention]

Photosensitive compositions used in conventional positive image forming materials include (1) a composition comprising an o-quinonediazide compound; a composition comprising an o-quinonediazide compound and an alkali-soluble resin such as a novolac resin;
This method utilizes the phenomenon in which an o-quinonediazide compound changes into an alkali-soluble substance when irradiated with light (for example, JP-A-50-125806, JP-A-61-
5251 etc.).

(2) Composition consisting of photosensitive diazonium salt and water-soluble resin A composition consisting of photosensitive diazonium salt and water-soluble resin such as polyvinyl alcohol, diacetone acrylamide-acrylamide copolymer,
This method takes advantage of the phenomenon in which a photosensitive diazonium salt and a water-soluble resin undergo a coupling reaction in an alkaline atmosphere and become water-insoluble (for example, in JP-A-1988-1992).
No. 101141, JP-A-56-101144, 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 safety problems in the development work 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. 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 colored images of arbitrary colors even if a coloring agent is added.

An object of the present invention is to provide a positive-working photosensitive sheet for producing a positive-working image-forming material that can be developed with water or hot water and is free from coloration due to photosensitive components or their decomposition products and color development caused by image-forming reactions. It is.

[Means to solve the problem]

The present inventors conducted extensive research on new positive-working photosensitive sheets that can be developed with water or hot water, and as a result, the following general formulas () and () were found. (However, in the above formula, R ₁ and R ₂ each independently represent a hydrogen atom or an alkyl group, Y ^- is a conjugated basic ion of an acid, and * is bonded to a water-soluble polymer via a linking group. A photosensitive layer formed on a support with a composition consisting of a water-soluble polymer and a synthetic resin emulsion having at least one selected from the stilbazolium group and the stilquinolium group as a photosensitive component addition group (indicates the bonding position). discovered a phenomenon in which a positive image can be obtained by exposing a positive manuscript to light, dipping it in water or warm water, and rubbing it with a sponge. In addition, the resulting image was free from coloration due to photosensitive components and color development due to image-forming reactions. The mechanism of this development is considered as follows.

Γ Exposure area When exposed to actinic light, the photosensitive component of a water-soluble polymer having a stilbazolium group or stilquinolium group as a photosensitive component addition group in the photosensitive layer undergoes a photodimerization reaction and becomes water-insolubilized. By immersing it in water or hot water, the water-insoluble water-soluble polymer easily swells, softening 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.

Γ Unexposed area When immersed in water or hot water, most of the water-soluble polymer having a stilbazolium group or stilquinolium group as a photosensitive component addition group in the photosensitive layer is eluted into the water or hot water. However, there is no change in the photosensitive layer, such as swelling or softening, and the adhesion to the support remains unchanged. Therefore, even if rubbed with a sponge, it will not be removed from the support, and an image will be formed with a component mainly composed of synthetic resin emulsion. Further, this image has no special coloring and is either colorless or the color of the added colorant is unchanged.

The present invention relates to a positive photosensitive sheet that utilizes the above phenomenon.

Hereinafter, the present invention will be explained in detail based on its embodiments.

The water-soluble polymer having the photosensitive component addition group used in the photosensitive layer of the photosensitive sheet of the present invention has the following general formulas () and (). (However, in the above formula, R ₁ and R ₂ each independently represent a hydrogen atom or an alkyl group, Y ^- is a conjugated basic ion of an acid, and * is a bonding position that is bonded to a water-soluble polymer via a linking group. ) is a water-soluble polymer having at least one selected from the stilbazolium group and stilquinolium group as a photosensitive component addition group, and the water-soluble polymer includes polyvinyl alcohol, polyacrylamide, polyvinyl Numerous examples include pyrrolidone, gelatin, casein, egg white, gum arabic, and mixtures thereof. In addition, the addition rate of the photosensitive component addition group to these water-soluble polymers is preferably 0.2 to 5.0 mol%; if it is less than this, sufficient water insolubilization will not occur, and if it is more than this, the miscibility with the synthetic resin emulsion will be poor. It may happen. These are Special Publication No. 56-5761 and Special Publication No. 56-5761.
No. 5762, JP-A-56-11906, JP-A-62-239145
It can be manufactured by the method described in No.

The synthetic resin emulsion used in the photosensitive layer of the photosensitive sheet of the present invention includes polyacrylic ester, ethylene-vinyl acetate copolymer, polyvinylidene chloride, polyvinyl acetate, polyvinyl chloride, polyester, and copolymers thereof. There are many examples including combinations and mixtures.

Furthermore, conventionally known water-dispersible coloring 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, if necessary.

The photosensitive layer of the photosensitive sheet of the present invention is composed of a water-soluble polymer having the photosensitive component addition group and a synthetic resin emulsion, but the solid proportion of the water-soluble resin having the photosensitive component addition group and the synthetic resin emulsion is 3:97~80:20, more preferably 5:95~
It's 40:60. If the amount of the water-soluble resin having a photosensitive component addition group is too large, the water resistance of the image will decrease and the image will fall off during development. Furthermore, the sensitivity of the formed photosensitive layer is significantly reduced. If there is too much synthetic resin emulsion, developability and image quality will deteriorate. If the value is significantly outside the above range, no image can be obtained. Furthermore, when adding colorants, the amount of coloring pigments is usually 30% or less, and the amount of water-soluble dyes is 10% or less based on the total solid content of the water-soluble resin having a photosensitive component addition group and the 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 layer coating solution for the photosensitive sheet of the present invention thus prepared is coated onto a support to produce a positive 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 laminated on both sides of polyethylene or polypropylene to make it waterproof. 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. Further, the photosensitive layer may be applied directly to the support, but in order to improve adhesiveness, it is desirable to perform corona discharge treatment, application of a primer treatment agent, or adhesive 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, etc., and mixtures thereof are used.
A coating thickness of m is preferred.

Coating onto the support may be carried out by any method such as a spin coater, roll coating, bar coating, or brush coating. The coating amount is approximately 1 to 5μ 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.

An image is formed on a positive image forming material prepared using the photosensitive sheet of the present invention 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) Immersion in water or warm water The exposed image forming material is immersed in water or warm water to swell the non-image areas. The water temperature at this time is
Although not particularly limited, higher temperatures can accelerate the swelling of non-image areas and shorten the immersion time. The water temperature depends on the selection of each component constituting the photosensitive composition, but from the viewpoint of workability,
℃, more preferably a water temperature of 25 to 45℃ is chosen. The immersion time is determined by the time required for the non-image area to swell sufficiently.

(3) Removal of non-image areas and drying Remove non-image areas by rubbing the photosensitive surface of the soaked image forming material with a sponge or the like moistened with water.
Then dry.

The mechanism of image formation on the photosensitive sheet of the present invention will be further explained in detail with reference to the drawings.

FIG. 1 shows the structure of a photosensitive film.

Here, the photosensitive film is a film in which a photosensitive layer is formed on a support.

The photosensitive layer consists of a synthetic resin emulsion, modified polyvinyl alcohol, 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 modified polyvinyl alcohol.

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 modified polyvinyl alcohol in the exposed portion is photodimerized by a photoreaction. The photodimerized product of modified polyvinyl alcohol that has been photodimerized and crosslinked through this reaction becomes water-insoluble;
Or it is easily swollen by 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, [exposed area] The photodimerized product of modified polyvinyl alcohol is water-insoluble, so it does not dissolve into water or hot water, but it absorbs water or hot water and swells. . Due to the swelling of the photodimerized product of the modified polyvinyl alcohol, the partial fusion of the synthetic resin emulsions is separated, and the synthetic resin emulsion is also peeled off from the support or becomes easily peeled off.

[Unexposed Area] Since the unreacted modified polyvinyl alcohol present between the layers of the synthetic resin emulsion is water-soluble, most of it is eluted from the photosensitive layer into water or hot water. At this time, development in which 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 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. In this way, a photosensitive film using the photosensitive sheet of the present invention as a photosensitive layer exhibits a positive action in which the unexposed areas form an image.

〔Example〕

In order to further clarify the present invention, Examples are shown below, but the present invention is not limited thereto.

Example 1 Solution A (photosensitive liquid) Stilbazonium group-introduced polyvinyl alcohol (1.25 mol% of N-methylstilbazonium groups introduced, average degree of polymerization)
1700, saponification degree 88%, 10% aqueous solution)
18.6 parts by weight Primal B-15 (46% liquid) (polyacrylic ester emulsion, manufactured by Nippon Acrylic Chemical Co., Ltd.) 15.7 parts by weight Carbon black dispersion 5.0 parts by weight Methanol 30.4 parts by weight Water 30.4 parts by weight However, carbon A black dispersion was obtained by dispersing in an ink mixer for 3 hours using the following formulation.

Carbon black 60 parts by weight Metrose 60SH4000 (Hydroxypropyl methylcellulose, manufactured by Shin-Etsu Chemical) 10 parts by weight Nonionic activator (polyethylene glycol alkyl phenyl ether mixture) 1 part by weight Water 229 parts by weight Rotated on one side of a 75 μm thick polyethylene terephthalate film Solution A was applied using a coating machine and dried with warm air at 90°C for 90 seconds to form a photosensitive layer with a thickness of 2 μm. Next, a positive original is placed in close contact with the photosensitive layer, and a 2kw
Exposure was performed for 10 seconds from a distance of 1 m using an ultra-high pressure mercury lamp. This material was immersed in warm water at 15°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 1.20. A relief positive image was obtained.

Example 2 Solution B (photosensitive liquid) Stilbazolium group introduced Gelatin (N-methylstilbazonium group introduced 2.5 mol%, 10% aqueous solution) 17.0 parts by weight Sumielite 1010 (50% liquid) (Ethylene-vinyl chloride copolymer emulsion, Sumitomo Chemical) (manufactured by Kogyo Co., Ltd.) 10.7 parts by weight Methanol 17.5 parts by weight Water 54.8 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 warm 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, leaving a colorless and transparent positive relief image. Obtained.

Example 3 Solution C (photosensitive liquid) Styrylquinolium group-introduced casein (1-methyl-4-(p-formylstyryl)quinolium group 1.0 mol % introduced,
10% aqueous solution) 20.5 parts by weight Vinibran 240 (45% liquid) (vinyl chloride emulsion, manufactured by Nissin Chemical Industry Co., Ltd.)
8.0 parts by weight Carbon black dispersion 6.5 parts by weight Methanol 30.0 parts by weight Water 35.0 parts by weight Apply liquid C on one side of a 75 μm thick polyethylene terephthalate film using a spin coater, dry it with hot air at 90°C for 60 seconds, A photosensitive layer with a thickness of 1.5 μm was formed. 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 product was immersed in warm water at 15°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 Liquid D (photosensitive liquid) Styrylquinolium group-introduced polyvinyl alcohol (1-methyl-4-
(p-formylstyryl)quinolium group 0.9
Mol% introduction, average degree of polymerization 1200, degree of saponification 88
%, 10% water soluble) 18. 6 parts by weight Sumikaflex 830 (50% liquid) (vinyl acetate-ethylene-vinyl chloride copolymer emulsion, manufactured by Sumitomo Chemical Co., Ltd.) 16.4 parts by weight Carbon black dispersion 5.0 parts by weight Methanol 30.0 parts by weight Water 30.0 parts by weight Thickness Solution D was coated on one side of a polyethylene terephthalate film with a thickness of 75 μm using a spin coating machine, and dried with hot 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. After immersing this product 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. Concentration 1.0
A relief positive image was obtained.

[Brief explanation of the drawing]

The drawings are all explanatory diagrams showing the mechanism of image formation of the present invention, and FIG. 1 shows a photosensitive film;
FIG. 2 is an explanatory diagram at the time of exposure, FIG. 3 is an explanatory diagram at the time of immersion in warm water or water, and FIG. 4 is an explanatory diagram at the time of development.

Claims (1)

[Claims] 1 The following general formulas () and () (However, in the above formula, R ₁ and R ₂ each independently represent a hydrogen atom or an alkyl group, Y ^- is a conjugated basic ion of an acid, and * is a bond bonded to a water-soluble polymer via a linking group. A water-soluble polymer and a synthetic resin emulsion having at least one type selected from stilbazolium group and stilquinolium group as a photosensitive component adducting group;
A positive-working photosensitive sheet that can be developed with water or hot water alone, further comprising a photosensitive layer having a thickness of 5 μm or less and comprising a colorant, if necessary, formed on the support sheet. 2. The photosensitive sheet according to claim 1, wherein the water-soluble polymer is at least one of polyvinyl alcohol, gelatin, and casein.