JPS6385622A - Diazo copying photosensitive paper - Google Patents

Abstract

PURPOSE:To form an image having high density and high contrast by forming a precoat layer from a composition composed of an UV absorber, a filler and a vinyl acetate resin. CONSTITUTION:The precoat layer 2 is composed of the layer of the composition contg. the UV absorber, the filler and the vinyl acetate resin. The UV absorber is incorporated into the precoat layer 2 together with the combination of the filler such as silica and the vinyl acetate resin, thereby forming the diazo photo sensitive layer 3, without forming any tarry substance. The discoloration of an image part due to light is controlled, and the coloring of a back ground due to light is controlled, without substantially reducing sensitivity, etc., of the diazo photosensitive layer.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a photosensitive paper for diazo copying, and more specifically, a precoat layer is provided between a paper base and a diazo photosensitive composition layer. This invention relates to improvements for improving photobleaching properties and improving image density and contrast in photosensitive paper of this type.

(Prior art) A photosensitive diazonium salt, an acid stabilizer and a coupler fi-7kr + 1.5 kr + 1.5 kr + 1.5 kr + 1.5 kr. Nine".

Liquids containing alkaline agents such as amines or ammonia
The two-component diazo copying method, in which images are formed by developing with a developer made of water vapor, is widely used as a low-cost copying method.

However, the table shows that in such a diazo copying method, the dye-forming components such as photosensitive diazonium salts or foggers and the formed diazo dye itself have a strong tendency to permeate into the paper substrate. The disadvantage is that the density of the image formed is still low compared to the amount of dye used and the amount of dye actually formed during development.

In order to improve this drawback, a brecoat stone containing a filler such as silica and a resin is provided between the paper substrate and the diazo photosensitive layer in advance, so that the paper substrate of the dye-forming component and the diazo dye can be used. It has been proposed and put into practical use to prevent penetration into the interior and improve image density and contrast.

(Problems to be Solved by the Invention) However, when a copy made by the diazo copying method is stored, photobleaching of the dye progresses rapidly in the image area, while coloring of the background occurs in the image area. There is a problem in that the image density and contrast of copies are significantly reduced. In particular, pre-coated type diazo photosensitive paper for copying has a remarkable tendency to fade and discolor.The reason for this is that with pre-coated type diazo photosensitive paper, the diazo photosensitive layer exists almost only on the surface of the paper. This is thought to be due to the fact that the influence of silica is significant and that fillers such as silica and resins present in the precoat layer act to promote photofading and discoloration.

Therefore, an object of the present invention is to provide a precoat type that is capable of forming a high-density, high-contrast image by exposure and development, and that reduces photobleaching of a dye image and coloring caused by background light. To provide a photosensitive paper for diazo copying.

(Means for Solving the Problems) The present inventors have discovered that K between the paper substrate and the diazo photosensitizer composition layer is
It has been found that the above problems can be effectively solved by providing a pre-coat layer with a composition containing an ultraviolet absorber, a filler and a vinyl acetate resin.

According to the present invention, in the photosensitive paper for diazo copying, which comprises a filler-containing precoat layer provided on a paper base and a diazo photosensitive composition layer provided on the precoat 1, the # precoat layer contains an ultraviolet absorbent filler. and a vinyl acetate resin.

(Function) In FIG. 1 showing the cross-sectional structure of the photosensitive paper for diazo copying of the present invention, a precoat layer 2 is provided on one surface of the paper base 1, and on this precoat layer 2, a diazo photosensitive agent composition is formed. A material layer 3 is provided. A back coat layer 4 is provided on the back side of the paper substrate 1 to prevent the curling tendency of the photosensitive paper.

In the present invention, as the precoat layer 2, an ultraviolet absorber,
It is characterized by using a layer of a composition containing a filler and a vinyl acetate resin.

Generally, it is known to incorporate an ultraviolet absorber into a product in order to prevent the product from photofading or photodeterioration. However, it seems very strange that ultraviolet absorbers are not generally incorporated into diazo photosensitive compositions in order to prevent photofading of copies of photosensitive paper for diazo copying. In fact, when an ultraviolet absorber is blended into a diazo photosensitive composition, a reaction occurs between the diazonium salt and the ultraviolet absorber, and the diazonium salt turns into tar, making it difficult to form a photosensitive layer and causing temporary scratches. It has been found that even if the photosensitive layer is forcibly formed, the sensitivity of the photosensitive layer decreases due to light absorption by the ultraviolet absorber, resulting in a significant decrease in image density.

According to the present invention, this ultraviolet absorber is provided in the precoat layer 2 in combination with a filler such as silica and a vinyl acetate resin, thereby preventing the formation of diazo-like substances. The photosensitive layer 3 can be formed without actually reducing the sensitivity of the diazo photosensitive layer.
This makes it possible to suppress photobleaching of the image area and suppress photocoloring of the background.

The vinyl acetate resin used in the present invention is characterized in that it can be easily applied to a paper substrate in the form of an aqueous emulsion, and that it can be easily formed into a film after drying to form a relatively water-resistant film. In this way, by incorporating an ultraviolet absorber into the vinyl acetate resin and forming a precoat layer, the transfer and redispersion of the ultraviolet absorber to the diazo photosensitive layer is suppressed, and its fixation to the precoat l is inhibited. This is considered to be the reason why the formation of tar-like substances is suppressed and the substantial decrease in sensitivity of the diazo photosensitive layer is suppressed. In addition, fillers such as silica added to the pre-coat layer not only have the effect of improving the texture of the coat layer, but also
It is believed that its large specific surface area has the effect of holding the ultraviolet absorber on the surface and dispersing it evenly and uniformly in the precoat layer.

The ultraviolet absorber contained in the precoat layer absorbs light such as ultraviolet rays through the photosensitive layer after exposure and development, suppresses photofading of the diazo dye in the photosensitive layer, and also removes unreacted parts of the parapuffer 2-round area. It is recognized to prevent discoloration of couplers and decomposed diazonium salts.

(Description of structure) Ultraviolet absorber The ultraviolet absorber used in the present invention is one that can cut light with a wavelength of 350 nm or less, most preferably one with a wavelength of 400 nm.
It is preferable to use one that can cut the following light.

Suitable examples include, but are not limited to, the following passages:

A) Phenyl salicylate ultraviolet absorber Compounds of the general formula where R is a hydrogen atom or an alkyl group, such as pt-butylphenyl salicylate.

B) Benzophenone ultraviolet absorber In the general formula, ring A may be substituted with a hydroxyl group or an alkoxy group, and 33B may be substituted with a hydroxyl group, an alkoxy group, a halodane atom, or a group of sulfonic acid or a salt thereof. For example, 2-hydroxy-4-methoxybenzophenone-5-sodium sulfonate, 2,2'-dihydroxy-4,4'-zomethoxypenzophenone, etc.

C) Benzotriazole ultraviolet absorber In the general formula, ring A can be substituted with a halogen atom, ring B can be substituted with a halogen atom, an alkyl group, etc. (2-(2'-hydroxy-3'-t
-butyl-5'-methylphenyl>-5-chlorobenzotriazole) 1 (2-(2-hydroxy-5-methylphenyl)benzotriazole) and the like.

Among these UV absorbers, benzotriazole UV absorbers are particularly effective in preventing photofading and discoloration.

As the vinyl acetate resin for the precoat layer, a resin whose main repeating unit is vinyl acetate is used, and this resin may be a homopolymer such as polyvinyl acetate, or an acrylate such as ethyl acrylate. , a copolymer containing a small amount of methacrylate such as methyl methacrylate as a comonomer. Furthermore, a partially saponified product of polyvinyl acetate, or a partially saponified, partially acetalized or butyralized product may be used. The degree of polymerization of the vinyl acetate resin is within the range that allows film formation, generally the average degree of polymerization is 500 to 100.0.
A value within the range of 00 is preferable. It is desirable to use these in the form of an aqueous latex having a solid content of 30 to 60 parts by weight.

Examples of inorganic fillers include silica such as gas-phase silica and wet-process silica such as Aerosil, talc, diatomaceous earth, magnesium oxide, calcium carbonate, barium sulfate, magnesium carbonate, various clays, gypsum, titanium divalent, etc. Preferably used. Among these, silicas are preferred; vapor-phase silica is advantageously used for dry-development paper, and wet-process silica is advantageously used for semi-dry development paper.

As a composition for forming precoat 1, on a dry basis,
10 to 80% by weight of vinyl acetate resin, especially 20 to 60% by weight, 0.01 to 20% by weight of ultraviolet absorber,
In particular, 0.1 to 10% by weight and 10 to 80% by weight of a pharyngeal agent.
It is preferable to use a composition of 20 to 60% by weight, particularly 20 to 60% by weight. This composition is used in the form of an aqueous composition, ie an aqueous dispersion, to form the precoat layer. Among ultraviolet absorbers,
In the case of a water-soluble compound such as a compound having a sulfonate group, it may be added in the form of an aqueous solution, and in the case of a poorly water-soluble or water-insoluble compound, it may be added in the form of an aqueous emulsion or It may be added to the aqueous dispersion in the form of a solution in a water-miscible organic solvent such as alcohol.

This aqueous dispersion may optionally contain any compounding agents known per se. For example, a lubricant such as wax may be blended to improve paper feeding properties, and a leveling agent such as silicone may be blended to improve smoothness. The concentration of the aqueous dispersion is preferably 1 to 20% by weight solids concentration from the viewpoint of coating workability.

Production of Photosensitive Paper When producing diazo photosensitive paper, the above-mentioned composition for forming a precoat layer is applied to at least one surface of a paper substrate such as photosensitive paper base paper. The coating amount is 0.5 to 511/ff/, especially 1 to 41/rr based on solid content per coated surface.
A range of l is appropriate. For forming the precoat layer, a coating mechanism known per se, such as a roll coater, a wire coater, an air knife coater, a reverse coater, a kit coater, etc., can be used. Dry to form a pre-coat layer.

After forming the precoat layer, a diazo photosensitizer composition containing a photodegradable (photosensitive) diazonium salt, a coupler, and an acid stabilizer is formed on the precoat layer.

As the photosensitive diazonium salt, any diazonium salt can be used as long as it is photodegradable itself and capable of pulling with a coupler under normal development conditions. Examples of the diazo compounds constituting these diazonium salts include, but are not limited to, the following.

4-Diazo-N,N-dimethylaniline (abbreviated as MA salt) 4-Diazo-N,N-diethylaniline (abbreviated as KA salt) 4-Diazo-N-ethyl-N-β-hydroxyethylaniline (abbreviated as EH salt) ) 4-Diazo-N,N-bis-β-hydroxyethylaniline 4-Diazo-N-methyl-N-β-hydroxyethylaniline 4-Diazo-N-ethyl-N-β-hydroxypropylaniline 4 -Diazo-N-ethyl-N-(β-diethylamino)-
Nithylaniline 4-Schiff! -2-chloro-N,N-diethylaniline 4-diazo-2-methyl-N,N-diethylaniline 4-diazo-2-fiodoN,N-noethylaniline 4-diazo-2-trifluoromethyl-N , N-diethylaniline 4-noacyNethyl-N-benzylaniline 4-diazo-Nmethyl-N-benzylaniline (abbreviation methylbenzyl) 4-diazo-2,5-dibutoxy-N,N-diethylaniline 4-siacy 2,5-shedoxy-N-benzoylaniline (abbreviated as BB salt) 4-diazo-2,5-shedoxy-N-ethyl-N-
Benzoylaniline 4-Diazo-2,5-zonezyloxy-N-benzoylaniline 4-Diazo-2-chloro-5-methoxy-N-benzoylaniline 4-Diazo-2,5-shedoxy-N-benzoyl-
Methylaniline 4-diazo-2,5-shedoxy-N-benzoyl-
Oxymethylanilineno9-lasoazodiphenylamine 4-diazo-2,5,4'-triethoxydiphenylamine 4-diazo-2,5,4'-triethoxydiphenyl 4
,4'-bisdiazo-2,2',5,5'-tetrahydroxydiphenylmethanebisdiazo-8,8'-dichloro-5,5'-dimethoxybenzidine 4-diazo-2,5-dimethoxyphenylethyl sulfide 4 -Diazo-2,5-jethoxy-4'-methyl-diphenyl-sulfide 4-diazo-2,5-dibutoxy-N-phenylmorpholine 4-diazo-2,5-jethoxy-N-phenylmorpholine 4-diazo -2-methoxy-N-thiomol7olin4-diazo-N-phenylpiperidine4-diazo-N-7enylpyrrolidine4-diazo-2,5-di-n-butoxy-N-phenylpiperidine2-diazo-4 -Methylmercaguteau N, N'-
Dimethylaniline 2-diazo-5-benzoylamino-N, N'-
Dimethylaniline 2-diazo-1-naphthol-5-sulfonic acid.

The diazo compounds described above are used as relatively stable diazonium salts as sulfates or hydrochlorides, or as double salts with zinc chloride, tin chloride, aluminum sulfate, etc. Further, stabilization methods such as allylsulfonate (diazonium salt of aromatic sulfone) and diazosulfonate can also be used.

As acid stabilizer, any organic or inorganic acid can be used, e.g.
, sulfosalicylic acid, p-)luenesulfo/acid, citric acid, tartaric acid, citric acid, sulfamic acid, maleinoic acid,
Phosphorus, etc. are used.

The coupler used is also well known per se, and any compound capable of coupling with the above-mentioned diazonium salt can be used. Suitable examples include, but are not limited to:

Pyrogallol.

resorcinol, phloroglycin, pyrogallol, resorcin monoglycol 1-tek, Resorcin glycol ether, meta-aminophenol, para-aminophenol.

Diethylaminophenol, ortho(hydroxyethoxy)phenol, 2.5.6
-trimethylphenol, 2-hydroxymethylphenol, β-(2-hydroxyphenyl)-propioni, quacid, 2-(ω-phenylaminomethyl)-phenol, β-
(4-Methyl-2-hydroxyphenyl)-glutaric acid, 2,5-dimethyl-f5-(N-dimethylaminemethyl)-phenol, 1,3 dimethyl ether of pyrogallol.

N-lauryl-aminophenol, N-acyl-meta-aminophenol, metahydroxy-acetanilide, ortho-N-hydroxydiphenyl-mono-guanidine, /4-N-hydroxydiphenyl-siguanidine, 2.5- Dimethyl-4-morpholinomethylphenol, 2-methyl-5-improvyl-4-morpholinomethylphenol.

4-Morpholine methylresorcinol monomethyl ether.

3.3', 5-trihydroxydiphenyl, 3.3'
, 5.5'-tetrahydroxydiphenyl, 2.2'
, 4.4'-tetrahydroxydiphenyl, 2.4.
4'-)dihydroxydiphenyl-2'-sulfonic acid, 2.4,6.3',5'-pentahydroxydiphenyl, 2,2',4.4'-tetrahydroxydiphenyl sulfite, 2.3-dioxynaphthalene, β-naphthol, α-naphthol, 1.6-nooxynaphthalene, 2.7-shioxina7talene, 2.3-dihydroxynaphthalene-6-sulfonic acid, 2-naphthol-3 , 6-disulfonic acid, 2.7-dihydroxynaphthalene-3-sulfonic acid, 2.8-dihydroxynaphthalene-6-sulfonic acid.

1.8-dihydroxynaphthalene-8-sulfonic acid, 1.8-aminonaphthol-5-sulfonic acid, 2.7
-Sihydrooxynaphthalene-3,6-disulfonate, 1.8-penzoylinonaphthol-2-sulfonic acid, 1,8-dihydrooxynaphthalene-6-sulfonic acid, 2-hydroxy-3-naphthoate Acid-N-β-hydroxyethylamide, 2-hydroxy-3-su7toic acid-N,N-bis-β
-hydroxyethylamide, 8-hydroxy-2
-Naphthoethylamide-hydroxyethylamide.

1-(N-cal is ethoxymethylamino)-S-naphthol-4-sulfonic acid, 5-(/yaranitro)-benzamido-1-naphthol, 1-hydroxynaphthyl-7-phenylguanidine 2-hydroxy-naphthyl- 8-piguanidine, 1-
Naphthol-3-(N-β-hydroxyethyl)-sulfonamide, 1-naphthol-3-(N-0-methoxyphenyl)-
sulfonamide, bis-[5-oxy-7-sulfo-naphthyl(2)]anne.

N,N-bis[1-oxy-3-sulfo-naphthyl(6
)]-thioeria, 1-phenyl-3-methylpyrazolone (5), acetoacetic acid, doanilide, 1-phenyl-3-cargexivirazolone, acetoacetic acid cyclohexylamide, acetoacetic acid benzylamide, Cyanoacetanilide, cyanoacetomorpholine, 1-(3'-sulfoamido)-phenyl-3-methylpyrozolone-5, 1-(4'-carboxy-ethylphenyl)-3-dodecyl-pyrazolone-5, 8-hydroxy-1 , 2-naphthiimidazole, 2-
Methyl-4-hydroxypenzimidazole, 7-methyl-4-hydroxybenzothiazole, 1.
7-nomethyl/l/-4-hydroxybenzotriazole, 3-hydroxythiophene-5-carboxylic acid, etc. These couplers can be used alone or in combination of two or more.

In addition to the above-mentioned essential components, the diazo photosensitive composition of the present invention may contain compounding agents known per se, such as wetting agents, stabilization aids, development accelerators, extenders, dispersants, pigments, etc. Each of these components is dissolved or dispersed in a solvent such as water to prepare a coating composition. A typical example of this prescription is as follows.

Two-component diazo photosensitizer composition Diazonium salt 0.1 to 4.0% Kagura 0.1 to 5.0% Acid stabilizer
2 to 10,0 development accelerator
2 to 10.0% extender 〇
1 to 10.0% dispersant 1 to 1
, 0% dye 0 to 0. OO3%
Solvent A polyhydric alcohol such as ethylene glycol or diethylene glycol can be used. Further, as the extender, dextrin, gum arabic, colloidal silica, starch, etc. are used. As the dye, blue dyes such as methylene blue and patent blue, or fluorescent whitening agents are preferably used in order to clarify the photosensitive surface or further increase the whiteness of the background.

The coating amount of the diazo photosensitive composition varies depending on the type of substrate and the development method, but - generally speaking, the coating amount of the diazonium salt is 0.05 to 0.21/rr. ,
Especially 0.09 to 0.15. Any material that falls within the range of li'/m' may be used.

The diazo photosensitive layer can be coated in the same manner as the precoat layer.

As a pack coat layer for preventing the curling tendency of photosensitive paper, in addition to the above-mentioned precoat layer, a wetting agent made of polyhydric alcohol such as ethylene glycol, propylene glycol, diethylene glycol, glycerin, or polyvinyl alcohol can be used. A coating layer of can be used.

Exposure and development of the diazo copying photosensitive paper of the present invention can be carried out in the same manner as known copying methods. For example, exposure is carried out through the document using a fluorescent lamp, mercury lamp, etc. as a light source, and dry development using ammonia-steam vapor is carried out. Alternatively, development is carried out by semi-dry development using an organic base such as monoethanolamine, jetanolamine, triethanolamine, morpholine, or guanisine.

Examples of the present invention are shown below.

Example 1 As a composition for forming a precoat layer: Silica (Thyroid P-244: Fuji Depuyson Co., Ltd.) 50 g Polyvinyl acetate emulsion (solid content 56%: Showa Kobunshi Co., Ltd.) 70.9 Ultraviolet absorber (2-(2'-hydroxy-3'-1-butyl-5
'-Methylphenyl)-5-chlorobenzotriazole; solid content concentration 10 t (water dispersion type); Chipa Geigy Exhibition] Create a pre-coat liquid by adding water to 501 or more chemicals and mixing and dispersing to a total volume of 1 t. did. This pre-coat liquid was applied to base paper for diazo photosensitive paper (basis weight 6311/ff1') with a dry coating weight of 2.51//rr? It was coated with a wire spar to give a precoat layer and dried to form a precoat layer.

Next, on the precoat layer, as a composition for forming a diazo photosensitive bird, 10 citric acid. 9 tatami caffeine 2011・4-siacy 2.5-dibutoxy-N-phenylmorpholine chloride'+4znct213 9 @ 2-hydroxy-3-naphthoic version-N-β-hydroxyethylamide 12 g・zinc chloride 10. 9. Methylene blue o, osg1 so μ's humble f
A photosensitive solution was prepared by dispersing the proportions of 7 relcan n and 411
A photosensitive layer of /lri was formed.

The diazo photosensitive paper obtained as described above was developed with ED-800 manufactured by Sanda Kogyo ■, and the highest density and minimum density were measured, and the quality of photobleaching resistance, water resistance, and initial color density was confirmed. The results are shown in the table.

Example 2 In Example 1, a UV absorber was added to 2-hydroxy-4-methoxybenzophenone-5-ndium sulfonate (manufactured by Shonan Kagaku Kogyo Co., Ltd.) from the composition for forming a precoat layer.
The quality of a diazo photosensitive paper obtained in the same manner except that No. 59 was used was checked in the same manner, and the results shown in the table were obtained.

Comparative Example 1 Diazo photosensitive paper obtained in the same manner as in Example 1 except that the ultraviolet absorber was removed from the precoat layer forming composition was subjected to quality confirmation using the same procedure, and the results shown in the table were obtained.

Comparative Example 2 In Example 1, except for the precoat layer, only the photosensitive liquid was applied to base paper for diazo photosensitive paper (tsubo i6a, p/?F1') at a dry coating amount of 0.411/rr? The quality of the diazo photosensitive paper obtained by coating it with a wire paper and drying it so as to give the following properties was confirmed using the same procedure, and the results shown in the table were obtained.

Note 1. The densitometer used was TC-6D (manufactured by Tokyo Denshokusha).

2. Photobleaching property is measured using a fade meter (manufactured by Toyo Rika Kogyo Co., Ltd.)
K is shown as the concentration change value after 3 hours of irradiation.

3. The initial color density was expressed as the color density 10 seconds after development.

4. Water resistance was indicated by the residual rate (a) at the highest concentration after immersion in water at 20°C for 30 minutes and drying.

5. For sensitivity, use the second original drawing (manufactured by Sanda Kogyo Co., Ltd.), ED-8
It is expressed as the printing speed (m/H) at which the density when printing and developing at 0.00 is the minimum density + 0.05.

As described above, the photosensitive paper for diazo copying of the present invention is capable of forming images with high density and high contrast;
A product with good photobleaching properties was obtained.

[Brief explanation of the drawing]

FIG. 1 shows the cross-sectional structure of the photosensitive paper for diazo copying of the present invention with a 1,000-inch mark M. - Backcoat layer.

Claims (1)

[Claims] (1) A diazo copying photosensitive paper comprising a filler-containing precoat layer on a paper base and a diazo photosensitive composition layer on the precoat layer, wherein the precoat layer contains an ultraviolet absorber filler and a vinyl acetate-based A photosensitive paper for diazo copying, characterized in that it is made of a composition containing a resin.