JPS6385624A - Diazo copying 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 a UV absorber, a filler and a polyvinyl alcohol resin. CONSTITUTION:The precoat layer 2 is composed of the layer of the composition contg. the UV absorber, the filler and the polyvinyl alcohol resin. The UV absorber is incorporated into the precoat layer 2 together with the combination of the filler such as silica and the polyvinyl alcohol resin, thereby forming the diazo photosensitive 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 diazo copying paper, and more particularly, it relates to a type of diazo copying paper in which a precoat layer is provided between a paper base and a diazo photosensitive composition layer. The present invention relates to improvements in copying paper for improving photobleaching and improving image density and contrast.

(Prior Art) After exposing a two-component noazo photosensitive layer containing a photosensitive noazonium salt, an acid stabilizer and a coupler, it is developed with a solution containing an alkaline agent such as an amine or a developer consisting of ammonia-steam vapor. The two-component diazo copying method for forming images is widely used as a cost-effective copying method.

However, in this azo copying method, dye-forming components such as photosensitive noazonium salts or couplers, and the formed diazo dye itself have a strong tendency to permeate into the paper substrate, so the use of dye-forming components is difficult. The disadvantage is that the density of the image formed is still low compared to the amount of dye actually formed during development.

In order to improve this drawback, by providing a pre-coat layer containing a filler such as silica and a resin between the paper substrate and the noazo photosensitive layer, it is possible to remove the dye-forming components and the diazo dye from the paper substrate. 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 copies made by the diazo copying method are stored, photobleaching of the dye progresses significantly in the image areas, while background coloration occurs in the valve image areas, resulting in There is a problem in that the image density and contrast are significantly lowered and sound is generated. 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, which is affected by light. This is thought to be due to the fact that the color change 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 diazo copying method that is capable of forming a high-density, high-contrast image through exposure and development, and that also reduces photobleaching of dye images and coloring caused by background light. There is a paper to provide.

(Next Means to Solve the Problems) The present inventors have developed a composite precoat layer containing an ultraviolet absorber, a filler, and a polyvinyl alcohol resin between the paper substrate and the diazo photosensitive composition layer. It has been found that by providing this, the above problems can be effectively solved.

According to the present invention, in a diazo copying paper comprising a filler-containing precoat layer provided on a paper base and a diazo photosensitive composition layer provided on the precoat layer, the precoat layer contains an ultraviolet absorber, a filler, and a diazo photosensitive composition layer. A diazo copying paper is provided, characterized in that it is made from a composition containing a polyvinyl alcohol-based resin.

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

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 polyvinyl alcohol resin.

Generally, it is known to incorporate an ultraviolet absorber into a product in order to prevent the product from photofading or photodeterioration. However, what about photofading of copies of diazo copying paper? It seems very strange that ultraviolet absorbers are not generally added to diazo photosensitizer compositions to prevent this, but in reality, when ultraviolet absorbers are added to diazo photosensitizer compositions, , a reaction occurs between the siazonium salt and the ultraviolet absorber, turning the siazonium salt into tar, making it difficult to form a photosensitive layer, and even if a photosensitive layer is formed by force, the ultraviolet absorber absorbs light. It was found that the sensitivity of the photosensitive layer decreased and the image density decreased significantly.

According to the present invention, this ultraviolet absorber is combined with a filler such as silica and a polyvinyl alcohol resin,
This is provided in the precoat/82, which enables the formation of the diazo photosensitive layer 3 without generating tar-like substances, and also prevents photobleaching of the image area without substantially reducing the sensitivity of the diazo photosensitive layer. This makes it possible to suppress the photocoloring of the pack ground.

The polyvinyl alcohol resin used in the present invention is easy to apply to paper substrates in the form of an aqueous solution, and copy paper using polyvinyl alcohol resin in the precoat layer has high sensitivity and good color development during development. Although it has advantages, it tends to easily brown when left in an environment with sunlight.

In the present invention, when the polyvinyl alcohol resin contains an ultraviolet absorber to form a precoat layer, the browning of the polyvinyl alcohol resin is suppressed, and the coloring of the background, that is, the increase in background concentration is suppressed. This is the first characteristic. In addition, since the ultraviolet absorber is contained in the precoat layer, migration and redispersion of the ultraviolet absorber into the diazo photosensitive layer is suppressed, and it is fixed in the precoat layer, which suppresses the generation of tar-like substances. This is also considered to be the reason why 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 have the effect of retaining ultraviolet absorbers on the surface due to their large specific surface edges, allowing them to be uniformly distributed throughout the pre-coat layer. It is believed that it has the effect of dispersing it in a similar manner.

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 noazo dye in the photosensitive layer, and also absorbs unreacted couplers in the packed ground area. It is recognized that it also prevents discoloration of decomposed soazonium salts.

(Description of structure) Ultraviolet absorber The ultraviolet absorber used in the present invention is one that can cut light with a wavelength of 35 Q nm or less, most preferably one with a wavelength of 400 nm.
It is preferable to use one that can cut light of nm or less.

Suitable examples include, but are not limited to:

A) Phenyl salicylate-based ultraviolet absorber A compound having the general formula in which 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 ring B may be substituted with a hydroxyl group, an alkoxy group, a halogen atom, or a sulfonic acid or a salt thereof. compounds, such as 2-hydroxy-4-methoxybenzophenone-5-sodium sulfonate, 2.
7-dihydroxy-4,4'-nomethoxybenzophenone and the like.

C) Pen! ) IJ azole external radiation absorber In the general formula, ring A may be substituted with a halogen atom, and ring B may be substituted with a halogen atom, an alkyl group, etc., such as ( 2-(2'-hydroxy-3'-t
-butyl-5'-methylphenyl) -5-70 Lopenzotriazole L (2-(2-hydroxy-5-methylphenyl)benzotriazole) and the like.

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

Pre-coat layer The polyvinyl alcohol resin used in the present invention may be of any type as long as it is water-soluble, but resins with various degrees of saponification can be used depending on the degree of water resistance and coating workability required. . Generally, the water solubility of polyvinyl alcohol-based resins is maximum when the degree of saponification is in the range of 70 to 97 degrees, and the solubility decreases when the degree of saponification is lower or higher than this. In the present invention, it is desirable to use a material with a saponification degree of 80 to 95%, and the average degree of polymerization (2) is 200%.
A value in the range of 2,000 to 2,000 is desirable.

Suitable inorganic fillers include silica such as aerosol vapor phase silica and wet process silica, talc, diatomaceous earth, magnesium oxide, calcium carbonate, barium sulfate, magnesium carbonate, various clays, gypsum, titanium dioxide, etc. used. Among these, silicas are preferred, and 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 a precoat layer, on a dry basis,
The polyvinyl alcohol resin is 10 to 80 weight, especially 20 to 60 weight, and the ultraviolet absorber is 0.01 to 2.
0 heavy debt, especially 0.1 to 10 weight t%, and filler is 1
It is preferable to use a composition of 0 to 80% by weight and 4% by weight and Xf'V of 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 UV absorbers, in the case of water-soluble compounds such as compounds having sulfonate groups, it is sufficient to add them in the form of an aqueous solution, and in the case of poorly water-soluble or water-insoluble compounds, they may be added in the form of an aqueous solution. It may be added to the aqueous dispersion in the form of emulsion or 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 in the form of emulsion to improve paper feeding properties, and a leveling agent such as silicon 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. Coating rate is 0.5 to 5 based on solid content per coated surface! ! /m2, especially l to 49/m
A range of is appropriate. The pre-coat layer is formed using a coating mechanism known per se, such as a roll coater, a wire coater, an air knife coater, a p-1+1 coater, a coater, etc.
Kikusko-p- and the like can be used. The aqueous composition applied on the paper substrate is dried to form a precoat layer, and then a diazo photosensitizer composition containing a photodegradable (photosensitive) siazonium salt, a coupler, and an acid stabilizer is added. The material is formed on the precoat layer.

As the photosensitive siazonium salt, any siazonium salt can be used as long as it is photodegradable itself and can be coupled with a coupler under normal development conditions. Examples of the diazo compounds constituting these noazonium salts are as follows, but are not limited thereto.

4-NoacyN,N-trimethylaniline (abbreviation: MA salt) 4-NoacyN,N-diethylaniline (abbreviation: EA salt) 4-Diazo-N-ethyl-N-β-hydroxyethylaniline (abbreviation: gHunruto) Azo -N-ethyl-N-(βnoacylamino)
-Dithylaniline/4-diazo-2-chloro-N,N-soethylaniline 4-diazo-2-methyl-N,N-soethylaniline 4-noacy2-iodo-N,N-noacylaniline 4- Noacy 2- IJ Fluoromethyl-N,N-
Noacylaniline 4-Schiff: /'-Nethyl-N-pencylaniline 4-
Schiffcy N-methyl-N-pe/Tuluaniline (abbreviated as methylbenzyl) 4-cyacy2,5-noptoxy-N,N-zoethylaniline 4-cyacy2,5-shedoxy-N-benzoylaniline (abbreviated as BB salt) 4-noazi -2,5-noethoxy-N-ethyl-N-
Benzoylaniline 4-Noazo2,5-nopenoloxy-N-benzoylaniline 4-Noazo2-chloro-5-methoxy-N-benzoylaniline 4-Noazo-2,5-noethoxy-N-benzoyl-
Methylaniline 4-diazo-2,5-shiedoxy-N-benzoyl-
Oxymethylaniline baladiazodiphenylamine 4-noacy2.5.4'-)liethoxynophenylamine 4-diazo-2,5,4'-triethoxydiphenyl4
゜41-bissiacy2.2',5.5'-tetrahydroxydiphenylmethanebisnoazo-8,8'-fuchloro515'-nomethoxypentizone 4-cyacy2,5-nomethoxyphenylethyl sulfide 4- siacy 2,5-diethoxy-4'-methyl-tuphenyl-sulfide 4-cyacy 2,5-nopoxy N-phenylmorpholine 4-noethoxy 2,5-noethoxy N-phenyl 4-noacy 2-methoxy-N-thiomorpho Phosphorus 4-NoacyN-7enylpiberidine 4-Noazi-N-phenylpyrrolisine 4-Noacy2.5-Non-butoxy-N-phenylbiyridine 2-Noazi-4-methylmercapto-N,N'-tumethyl Aniline 2-noacy5-benzoylamino-N, N'-tmethylaniline 2-cyacy1-7to-5-sulfonic acid.

The diazo compounds described above are used as relatively stable noazonium salts as sulfates or hydrochlorides, or as double salts with zinc chloride, tin chloride, aluminum sulfate, etc. Further, stabilization methods such as allyl sulfonate (noazonium salt of aromatic sulfonic acid) and cyacysulfonate can also be used.

As the acid stabilizer, any organic or inorganic acid such as sulfosalicylic acid, p-toluenesulfonic acid, citric acid, tartaric acid, oxalic acid, sulfamic acid, maleic acid,
Phosphoric acid etc. are used.

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

Pyrocatechol, resorcin, 70 loglycine, pyrogarolloresorcin monoglycol ether, resorcin glycol ether, meta-aminophenol, para-aminophenol, soethylaminophenol, ortho(hydroxyethoxy)phenol, 2,5.6
-) Limethylphenol, 2-hydroxymethylphenol, β-(2-hydroxyphenyl)-propionic acid, 2-(ω-phenylaminomethyl)-phenol, β-
(4-Methyl-2-hydroxyphenyl)-glutaric acid, 2,5-trimethyl-6-(N-trimethylaminomethyl)
-phenol, 1.3-methyl ether of pyrrole, N-lauryl-para-aminophenol, N-7silyl-meta-aminophenol, metahydroxy-acetanilide, ortho-N-hydroxydiphenyl-mono-guanidine, Noglar N-hydroxysophenylzoguaninone, 2,5-tumethyl-4-mol 7-olinomethylphenol, 2-methyl-5-isopropyl-4-morpholinomethylphenol, 4-morpholinemethylresorcinol monomethyl ether, 3 , 3',5-)lihydrooxynophenyl, 3,
3'. 5.5'-tetrahydrooxynophenyl, 2,
2',4.4'-tetrahydrooxynophenyl, 2,
4.4'-trihydrooxynophenyl-2'-
Sulfonic acid, 2, 4.6.3'. 5'-hentahydrooxynophenyl, 2,2',4.4'-tetrahydrooxynophenyl sulfite, 2,3-dioxynaphthalene, β-naphthol, α-naphthol, 1,6-cyoxynaphthalene, 2.7-Sooxynaphthalene, 2.3-dihydroxynaphthalene-6-sulfonic acid, 2-naphthol-3,6-disulfonic acid, 2.7-dihydroxynaphthalene-3-sulfonic acid, 2.8-dihydro Oxynaphthalene-6-sulfonic acid, 1.8-dihydroxynaphthalene-8-sulfonic acid, 1.8-aminonaphthol-5-sulfonic acid, 2.7
-nohydroxynaphthalene-3,6-sulfonic acid, 1,8-hensylaminonaphthol-2-sulfonic acid, 1,8-dihydroxynaphthalene-6-sulfonic acid, 2-hydroxy-3-s7toic acid -N-β-hydroxyethylamide, 2-hydroxy-3-su7to-N,N-bis-β
-hydroxyethylamide, 8-hydroxy-2
-Naphthoic acid-hydroxyethylamide, 1-(N-calgaethoxymethylamino)-S-naphthol-4-sulfonic acid, 5-(nocranitro)-benzamido-1-naphthol, 1-hydroxina7thyl-7-phenylguanino /, 2-hydroxy-naphthyl-8-biguaninone, 1-
7toll-3-(N-β-hydroxyethyl)-sul7onamide, l-naphthol-3-(N-0-methoxyphenyl)-
Sulfonamide, bis-[5-oxy-7-sulfo-naphthyl(2)]amine, N,N-bis[1-oxy-3-sulfo-naphthyl(6)
)]-thiourea 1-phenyl-3-methylpyrazolone (5), acetoacetic acid anilide, 1-phenyl-3-carboxypyrazolone, acetoacetic acid cyclohexylamide, acetoacetic acid pencylamide, 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-hydroxybenzimidazole, 7-methyl-4-hydroxybenzothiazole, 1.
7-nomethyl-4-hydroxy-benzotriazole, 3-hydroxythiophene-5-carboxylic acid, 1.3.4-cyclopentatrione.

These couplers can be used alone or in combination of two or more.

In addition to the above-mentioned essential components, this diazo photosensitizer composition contains ingredients known per se, such as wetting agents, stabilizing agents,
A development accelerator, an extender, a dispersant, a pigment, etc. can be blended, and each of these components is dissolved or dispersed in a solvent such as water to prepare a coating composition. Representative examples of this prescription are as follows.

Two-component diazo photosensitizer composition noazonium salt 0.1 to 4.0% coupler
0.1 to 5.0% acid stabilizer
2 to 10.0 development accelerator 2 to 10
．． 0% Extengu 〇 to 1050chi Dispersant 1 to 1.0% Pigment
0 to 0.003% Solvent Residual Amount As the development accelerator, polyhydric alcohols such as glycerin, ethylene glycol, diethylene glycol, etc. can be used. Further, as the extensor, dextrin, gum arabic, colloidal silica, starch, etc. are used.

In addition, as the dye, a bluish dye such as methylene blue or glossy blue, or a fluorescent whitening agent is suitably used in order to clarify the photosensitive surface or further whiten the pack ground.

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 guazonium salt is 0.05 to 0.217 m2, particularly 0.09 to 0.217 m2. Any material within the range of 0.151/m2 may be used.

Noah! The photosensitive layer may be applied in the same manner as the precoat layer.

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

Exposure and development of the diazo photosensitive paper of the present invention can be carried out in the same manner as known copying methods. Development is carried out by dry development using an organic base such as monoethanolamine, noethanolamine, triethanolamine, morpholine, or semi-dry development using an organic base such as guanisine.

Examples of the present invention are shown below.

Example Pre-coat layer forming composition: Silica (Syroid P-244: manufactured by Fuji Dixson Co., Ltd.) 509 Polyvinyl alcohol (
Average degree of polymerization 500; degree of saponification 88%; manufactured by Nippon Gosei Kagaku Co., Ltd.) 40II 1 line absorber [2-(2'-hydroxy-3'-t-butyl-
5'-methylphenyl)-5-chloropene/ ) IJ
Assol; solid content iA degree 10% (water dispersion tie f); manufactured by Ciba Geigy] Water was added to chemicals of 501 or higher and mixed and dispersed so that the total amount was 11 VC:1 to prepare a precoat liquid. This pre-coat liquid was applied to base paper for diazo photosensitive paper (basis weight 639/m2) until the dry coating amount was 2.
．． It was coated with a wire spar to a thickness of 517 mK and dried to form a precoat layer.

Next, on the precoat layer, as a composition for forming a diazo photosensitive layer, Citric acid 10F.
Caffeine 2 (1,4-diazo-2,5-nopoxy N-phenyl'72 ZnC4z
1 3 Ji'・2-hydroxy-3-naphthoic acid-
A photosensitive solution was prepared by adding water to 12N N-β-hydroxyethylamide, 10 g of zinc chloride, and 0.05 g or more of methylene blue, and mixing and dispersing the chemicals to a total volume of 1 liter. This photosensitive solution was applied onto the precoat layer using a wire coater and dried to form a photosensitive layer with a thickness of 0.41/m2.

The diazo photosensitive paper obtained as described above was developed using fiED-800 manufactured by Sanda Kogyo Co., Ltd., and the maximum 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, the ultraviolet absorber was added to 2-hydroxy-4-methoxybenzophenone-5-sodium sulfonate (manufactured by Shonan Kagaku Kogyo Co., Ltd.) from the composition for forming a precoat layer.
The quality of the diazo photosensitive paper obtained in the same manner except that 5g was replaced was checked using the same procedure, and the results shown in the table were obtained.

Comparative Example 1 A diazo-sensitive paper obtained in the same manner as in Example 1 except that the ultraviolet absorber was removed from the glycoat layer-forming composition was subjected to quality confirmation using the same procedure, and the results shown in the figure 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 (basis weight 639/m2) using a wire spar so that the dry coating amount was 0.41/m2. The quality of the nine-zoazo photosensitive paper obtained by drying was checked in the same manner, and the results shown in the table were obtained.

Note 1. A TC-6D (manufactured by Tokyo Denden) was used as the concentration meter.

2. Photobleaching property is measured using a fade meter (manufactured by Toyo Rika Kogyo Co., Ltd.)
It 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 is shown by the maximum residual rate (sub) of d degree after being immersed in water at 20°C for 30 minutes and dried.

5. For sensitivity, use the second original drawing (manufactured by Sanda Kogyo Co., Ltd.), El)-
It is expressed as the baking speed (m/H) at which the density is the minimum density W + 0.05 when the material is developed in a furnace at a temperature of 800.

As described above, the diazo copying paper of the present invention is capable of forming high-density, high-contrast images, and has good photobleaching properties.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the cross-sectional purchase of the diazo copying paper of the present invention. Original side composition layer, 4... back coat layer. Patent applicant: Mita Kogyo Co., Ltd. - Agent: Patent attorney Ikuo Suzuki ρ-＼,

Claims (1)

[Claims] (1) A diazo copying paper in which a filler-containing precoat layer is provided on a paper base and a diazo photosensitive composition layer is provided on the precoat layer, wherein the precoat layer contains an ultraviolet absorber, a filler, and a polyvinyl alcohol resin. A diazo copying paper comprising a composition containing.