JPS6242151A - Production of diazo photosensitive paper - Google Patents

Abstract

PURPOSE:To permit the formation of a uniform and smooth precoat layer with high-speed coating and to reduce the heat energy cost necessary for drying by using an aq. compsn. contg. a silica filler, binder and specific condensed phosphate of an alkali metal as a compsn. for forming the precoat layer. CONSTITUTION:Photosensitive paper for diazo copying consists of a paper substrate, the precoat layer formed on the surface of said paper substrate and a photosensitive layer contg. the photodecomposable diazonium compd. provided on the one precoat layer. The precoat layer is formed of the aq. compsn. contg. the silica filler, org. binder and the condensed phosphate of the alkali metal expressed by the formula (1) or (2). The adequate silica filler is gaseous phase method silica which is widely known under the name of 'aerozyl(R)'. The adequate org. binder is a latex type binder resin. The silica filler and binder can be varied in the weight ratio over a fairly wide range and in general, said filler and binder are preferably used at 0.1:1-10:1 or 0.2:1-2:1 weight ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing diazo photosensitive paper, and more specifically, the present invention relates to a method for producing diazo photosensitive paper. The present invention relates to an improvement for lowering the viscosity of a precoat e-forming composition and making it possible to form a uniform and smooth precoat layer by high-speed coating when manufacturing paper.

(Prior art and technical problems of the invention) After exposing a one-component diazo photosensitive layer containing a photosensitive diazonium salt, it is developed with an alkaline solution containing a coupler, or alternatively, a one-component diazo photosensitive layer containing a photosensitive diazonium salt and a coupler is developed. After exposing the two-component diazo photosensitive layer, ammonia
The diazo copying method, which involves developing with water vapor or an alkaline solution, is widely practiced as a low-cost copying method.

However, in the photosensitive papers used in these diazo copying methods, dye-forming components such as photosensitive diazonium salts or couplers, as well as 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 not sufficiently high compared to the amount of forming components used and the amount of diazo dye actually formed during development. To improve this shortcoming.

Blenite M (sizing layer) is provided on the surface of the paper substrate,
It has been widely practiced for a long time to provide a diazo photosensitive layer on this precoat layer. This precoat composition typically consists of a combination of a silica filler and an organic binder, and various water-soluble resins and water-based dispersible resins are used as the organic binder. .

The effect of this precoat layer is to prevent penetration of photosensitive diazonium salts into the paper substrate, improving density, contrast, etc.
Furthermore, it has two major effects: increasing the apparent sensitivity and increasing the effective surface area of the photosensitive layer, as well as increasing the density and contrast through the pigment effect by retaining the formed dye on the particle surface. Separated.

However, when a silica-based filler is added to an aqueous dispersion of an organic binder, the viscosity of this dispersion increases considerably, making high-speed coating difficult. That is,
If the aqueous dispersion is coated at high speed with a near-knife coater or the like while the viscosity of the aqueous dispersion remains high, significant coating unevenness will occur on the paper surface, resulting in defects such as color unevenness and density unevenness in the copies. Thus, in order to prevent this, it is necessary to reduce the solid content concentration of the aqueous coating composition.
The disadvantage is that it is difficult to increase the volume and to achieve high speed application, and that the additional wood has to be evaporated, resulting in high thermal energy costs.

(Gist of the invention and purpose of the invention) Unreleased II! These authors have found that when a condensed alkali metal phosphate salt is contained in the aqueous composition for forming a precoat layer as described above, the viscosity of the aqueous composition is increased to +1i1-s without impairing the properties required for the precoat layer. It has been found that a uniform and smooth precoat layer can be formed by high-speed coating.

That is, one object of the present invention is to provide a method for reducing the viscosity of a composition for forming a precoat layer and enabling high-speed coating when producing diazo photosensitive paper having a precoat layer and a diazo photosensitive agent layer on a paper substrate. There is something to do.

Another object of the present invention is to provide a method that enables the formation of a uniform and smooth precoat layer by high-speed coating.

Still another object of the present invention is to form a water-based precoat layer! I
Maintain the solids concentration of the product at a high level.

As a result, it is an object of the present invention to provide a method that can reduce the cost of thermal energy required for drying.

(Structure of the Invention) According to the present invention, in a method for producing diazo-sensitive paper, which comprises applying a pre-coat layer on the surface of a paper substrate and then applying a diazo-sensitive agent layer on the pre-coat layer, A method is provided, characterized in that the composition is an aqueous composition containing a silica base, a binder, and a condensed alkali metal phosphate.

In the present invention, by containing the alkali metal salt of condensed phosphate in an amount of 0.01 to 1.0% by weight, particularly 0.05 to 0.51i%, based on the aqueous composition, various conditions required for diazo copying can be achieved. The above objectives can be achieved without impairing the properties.

(Characteristics and Effects of the Invention) As described above, the present invention uses an aqueous composition containing a silica filler, an organic binder, and a condensed alkali metal phosphate as a composition for forming a precoat layer. It has a remarkable feature in that it does.

Although free phosphoric acid itself is a known substance as an acid stabilizer for diazonium salts in diazo photosensitive layers, it has not yet been known to use condensed alkali metal phosphates for applications in diazo photosensitive paper.

Alkali metal salts of condensed phosphates are generally alkaline when made into aqueous solutions, and thus, when alkali metal salts of condensed phosphates are used in the production of diazo-sensitive paper, it is expected that a precoupling reaction between the diazonium salt and the coupler will occur. .

In the present invention, by incorporating this condensed alkali metal phosphate into the composition for forming a precoat layer, the viscosity of the composition for forming the precoat layer can be adjusted without causing troubles such as such precoupling reactions. It has been found that the precoat layer can be formed evenly and smoothly even by high-speed coating.

Conventionally, various organic type thinners are known as thinners for aqueous compositions. However, in the system of an aqueous composition containing a silica filler and an organic binder, which is the object of the present invention, condensed alkali metal phosphates are significantly superior to these organic thinners. This fact will become clear by referring to the tjSi table below.

i1 table 1 ko 1 rin 1 breath 1 melody ”! Σ Honghuang Bao Want Lisu Shi 0 7.8 to half staric acid 4 0.15
El・0 organic thinner A O,15
7,3 Organic Thinner B O,158,8 Organic Thinner CO,15B,8 As the aqueous composition, the base composition described in the Examples described below was used.

(Preferred Embodiment of the Invention) A first diagram showing the cross-sectional structure of the photosensitive paper for diazo copying according to the present invention.
In the figure, this photosensitive paper consists of a paper substrate 1, a precoat layer 2 applied to the surface of the paper substrate, and a photosensitive layer 3 containing a photodegradable diazonium compound provided on one of the precoat layers 2. .

A feature of the present invention is that this precoat F32 is formed from an aqueous composition containing a silica filler, an organic binder, and a condensed alkali metal phosphate.

The condensed alkali metal phosphate has a chemical structure represented by the following general formula, where M is an alkali metal and n is a positive integer including zero.

Representative examples of the formula (1) include sodium birophosphate, sodium tripolyphosphate, and sodium tetrapolyphosphate, and a representative example of the formula (2) is sodium hexametaphosphate. Any of these can be used for the purpose of the present invention, but sodium hexametaphosphate is particularly advantageous because it has acidic liquid properties and has a large tendency to reduce viscosity.

In this precoat composition, the silica filler mainly acts to increase the specific surface of the photosensitive layer and impart a pigment effect to the dye formed. It works to improve the texture of paper and also improve its writing characteristics.

A suitable silica intermediary agent is vapor phase silica, which is widely known under the name Aerosil. Vapor-phase silica is amorphous silica with an extremely fine primary particle size, and its specific surface area is 50 get' or more, especially 100 get'.
', and the dispersed particle size is generally 0.1 to 20u.
It is within the range of Lm.

As the organic binder, either a water-dispersible type or a water-soluble type organic binder can be used, but a latex type binder resin is preferred. This latex-type thermoplastic resin exists in the coating liquid in the form of spherical particles with an emulsion size, that is, a particle size of 0.1 to 10 microns, and this resin is present between the silica gel particles and between the silica gel particles and the paper substrate. This property, which exhibits excellent binding properties without impeding the pigment effect, is due to the fact that even after the pre-coat film is formed, the remains of the emulsion particles remain. Seem. Latex type thermoplastic resin binders include those conventionally known as latex type or emulsion type 16ffl agents, such as polyvinyl acetate latex, vinyl acetate-vinyl chloride copolymer latex, acrylic resin emulsion, styrene-acrylic copolymer. Emulsions, vinyl chloride-acrylic copolymer emulsions, etc. can be used, but styrene-
The effect is remarkable when the present invention is applied to acrylic copolymer emulgene.

The amount ratio of silica-based additive to binder can vary over a fairly wide range, but generally speaking.

0.1: 1 to 10:1 0.2:1 to 2:1 It is desirable to use a weight ratio of .

If the amount of the silica-based additive is less than the above range, the above-mentioned effects will be unsatisfactory, while if it is more than the above range, the permeation of the photosensitive composition will be large and the precoat phase will be easily peeled off. occurs. On the other hand, when the amount of this latex resin is less than the range specified in L, the binding of silica particles tends to be unsatisfactory, and when it is more than the above range, both the pigment effect and the anti-bleeding effect tend to be unsatisfactory. .

This composition for forming a precoat layer has a solid content concentration of 0.1
It is used as an aqueous composition in an amount of 0.5 to 50% by weight, especially 0.5 to 30 gL, but in the present invention, 0.01 to 1.0% by weight, especially 0.05 to 0. Contains .5% by weight of condensed alkali metal phosphate. That is, when the content of the alkali metal salt of condensed phosphate is less than the above range, a sufficiently satisfactory viscosity reduction effect cannot be obtained, whereas when it is more than the above range, the content is reduced by pre-coupling between the diazonium salt and the coupler. In some cases, defects such as fogging may occur.

In the photosensitive paper of the present invention, the basis weight of the paper base (paper 880 mm
The weight per area (Kg) of X1100 weight 1 can be varied over a wide range, ranging from a thin one like 50Kg to 6
Even relatively thick materials such as 8 kg can be used for the purpose of the present invention.

In order to provide a precoat layer on this paper substrate, a coating liquid of the above-mentioned composition is prepared, and this coating liquid is coated in a solid content of 0.5 to 4.0 g/m2, particularly 1.0 g/m2.
5 to 2.0 g/w2 Coating is performed by any means known per se, such as a coating roller, an air knife coater, a bar coater, a blade coater, a reverse coater, a hard coater, spraying, dip coating, etc. This coating composition may contain one or more additives known per se, such as plasticizers, solubilizers or dispersants, organic solvents, and the like.

A diazo photosensitive layer composition known per se is then provided on this precoat layer.

As the photosensitive diazonium salt contained in this diazo photosensitive layer, any diazonium salt can be used as long as it is photodegradable and can be coupled with a coupler used in the diazo copying method under normal development conditions. I can do it.

As the acid stabilizer to be contained in the diazo photosensitive layer, 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.

In the case of a two-component diazo photosensitizer composition, a coupler is contained in addition to the above-mentioned essential components. Such couplers are also well known per se, and any compound capable of coupling with the aforementioned diazonium salts can be used.

In addition to the above-mentioned essential components, the diazo photosensitive composition used in the present invention contains, of course, additives known per se, such as wetting agents, stabilizing agents, development accelerators, extending agents, and dispersing agents.
A pigment and the like can be blended, and each of these components is dissolved or dispersed in a solvent such as water to form a coating composition. Representative examples of this treatment are as follows.

(1) Two-component diazo photosensitizer composition diazonium salt 0.1 to 4.0% coupler
0.1-5.0% acid stabilizer
2 to 1000% Development accelerator 2 to 10.0% Extender 〇 to 10.0%
Dispersant 0 to 1.0% dye
0 to 0.003% Solvent Remaining amount (2) - Component-based diazo photosensitizer composition Diazonium salt 0.1 to 4.0% Acid stabilizer
2.0 to 10.0% stabilizing agent
0 to 10.0% Extender 0 to 1000% Dye O to 0.003%
Solvent Remaining Amount The coating 1+tl of the above-mentioned photosensitive composition varies depending on the type of substrate and development method, but generally speaking,
The coating amount of diazonium salt is 0.05 to 0.2 g/m2
In particular, it may be in the range of 0.075 to 0.15 g/s2.

Image exposure and development of this photosensitive layer can be easily carried out by means known per se.1 For example, exposure is carried out through the document using light from a light source such as a fluorescent lamp, a low-pressure mercury lamp, or a high-pressure mercury lamp; , dry development using ammonia-steam,
Semi-dry development or wet development using an organic or inorganic base can be applied.

The invention is illustrated by the following example.

(Example) Sodium hexametaphosphate as a precoat layer forming composition 1.5
g-Polyvinyl acetate (Movinyl DC: manufactured by Hoechst Gosei Co., Ltd.) 20 g
e-silica (Si02; Aeroseal #200, manufactured by Nippon Aeroseal Co., Ltd.)...3
0.

S# 1801. (manufactured by Inuyukayakusha) ・・・・・・50
.

Water was added to the above chemicals so that the total amount was 12. After uniformly dispersing or dissolving the solution with this composition using an ultra-high-speed stirrer, air was applied to base paper for photosensitive paper (tsubo Q: 63 g/+m2).
Using a knife coater, the coating amount was 2.0 g/ml4.
The varnish bead was applied at a rate of 2500 m/hour and dried to form a precoat layer.

Next, 4-diazo-2,5 dibutoxy-N-phenylmorpholine chloride% ZnCl2 was added to the precoat layer as a composition for forming a diazo photosensitive agent layer.
・・・・・・13g? -Hydroxy-3-naphthoic acid-N-β-hydroxyethylamide ・・・・・・・・・・・・・・・
・・・・・・12g citric acid ・・・・・・
・・・・・・・・・・・・・・・ 7g zinc chloride
・・・・・・・・・・・・・・・・・・・・・
1g rice starch ・・・・・・・・・・・・・・・・・・
・・・・・・5g Kagakusha) ・・・・・・・・・
・・・・・・・・・・・・ 5g thiourea
・・・・・・・・・・・・・・・・・・・・・ 2g
Diethylene glycol ・・・－・・・・・・・・・Fist・
・ 3g Methylene Flu-B Conc t・・・・・・1
A solution of 0.12 g of water was added to make a total volume of one coat, and the solution was uniformly coated using an air knife coater and dried to obtain diazo photosensitive paper.

The diazo photosensitive paper obtained as described above was exposed and developed using Copistar ED-800 (manufactured by Sanda Kogyo Co., Ltd.) as a document, and as a result, an even blue image was obtained.

(Comparative Example 1) Diazo photosensitive paper was obtained in the same manner as in Example except that borax was removed from the composition for forming a precoat layer. The resulting diazo photosensitive paper was exposed to light over the original using ED-800 manufactured by Sanda Kogyo Co., Ltd., and developed, resulting in an image with uneven shading in both image and non-image areas. In particular, unevenness was noticeable in the halftone area.

(Comparative Example 2) The composition for forming a precoat layer was heated with air in the same manner as in Comparative Example 1.
While adjusting the coating amount to 2.0 gem' using a knife coater, the coating was applied at a coating speed of 1500 m/hour, and dried to form a precoat layer.

Next, a diazo photosensitive agent layer was formed on the precoat layer at the same time as in the example to obtain a diazo photosensitive paper.

The resulting diazo photosensitive paper was exposed with a 1 g draft using Copistar ED-800 manufactured by Sanda Kogyo Co., Ltd. and developed, resulting in a uniform image. However, the varnish beading of the precoat layer was delayed.

[Brief explanation of drawings]

FIG. 1 is a sectional view illustrating the diazo photosensitive paper of the present invention. 1...Paper quality, 2...Precoat layer, 3...Diazo photosensitive agent layer.

Claims (3)

[Claims] (1) In a method for producing diazo photosensitive paper, which comprises applying a precoat layer to the surface of a paper substrate and then coating a diazo photosensitive agent layer on the precoat layer, a silica-based filler is used as the composition for forming the precoat layer. , a binder and an aqueous composition containing a condensed alkali metal phosphate. (2) The amount of condensed alkali metal phosphate is 0.00% per aqueous composition.
2. A method according to claim 1, wherein the compound is present in an amount of 0.01 to 1.0% by weight. (3) The method according to claim 1, wherein the alkali metal salt of condensed phosphate is sodium hexametaphosphate.