JPS6242150A - Manufacture of diazo photosensitive paper - Google Patents

Abstract

PURPOSE:To decrease the viscosity of a compsn. for forming a precoat layer and to permit coating at a high speed by using an aq. compsn. contg. a silica filler, binder and borax as the compsn. for forming the precoat layer. CONSTITUTION:The aq. compsn. contg. the silica filler, binder and borax is used as the compsn. for forming the precoat layer in a process for producing a diazo photosensitive paper consisting in coating the precoat layer on the surface of a paper substrate, then coating a diazo photosensitive agent layer on the precoat layer. The borax is made to exist at a ratio of 0.01-1.0wt% per weight % of the aq. compsn. The adequate silica filler is gaseous method silica and the org. binder of either a water dispersion type or water soluble type is used for the org. binder. A latex type binder resin is more adequate. The weight ratio of the silica filler and the binder can be varied 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. The present invention relates to improvements in reducing the viscosity of a composition for forming a precoat layer and making it possible to form a uniform and smooth precoat layer at 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 the photosensitive diazonium salt and the coupler are The diazo copying method involves exposing a two-component diazo photosensitive layer and then developing it with ammonia-steam or alkaline solution.
It is widely used 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 formed image is still not high compared to the amount of forming components used and the amount of diazo dye actually formed during development. In order to improve this shortcoming,
A precoat layer (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 an air 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. Therefore, in order to prevent this, it is necessary to reduce the solid content concentration of the aqueous coating composition, increase the coating amount, and make it difficult to perform high-speed coating 11i. The disadvantage is that the cost of heat energy increases because it has to be emitted to the surrounding area.

(Summary of the Invention and Object of the Invention) The present invention provides that, when boric acid is contained in the above-mentioned aqueous composition for forming a precoat layer, it can be added to the aqueous composition without impairing various properties required for the precoat layer. It has been found that the viscosity of the precoat layer can be significantly reduced, and a uniform and smooth precoat layer can be formed by high-speed coating.

SUMMARY OF THE INVENTION The object of the present invention is to provide a method for reducing the viscosity of an Ml composition for forming a precoat layer and enabling high-speed coating when producing diazo photosensitive paper having a paper texture and a precoat layer and a diazo photosensitive agent layer. The offer is to provide.

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 provide a method capable of maintaining the solid content concentration of an aqueous composition for forming a precoat layer at a high level, thereby reducing the cost of thermal energy required for drying.

(Structure of the Invention) According to the present invention, in a method for producing a diazo-sensitive paper comprising 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 composition for forming the pre-coat layer is provided. There is provided a method characterized in that it uses an aqueous composition containing a silica-based filler, a binder, and boric acid.

In the present invention, the above objective can be achieved without impairing the various properties required for diazo copying by making boric acid present in an amount of 0.0 to 1.0% by weight in the aqueous composition. I can do it.

(Characteristics and Effects of the Invention) As described above, the present invention is remarkable in that an aqueous composition containing a silica filler, an organic binder, and boric acid is used as a composition for forming a precoat layer. It has unique characteristics.

Free borax itself is a known substance as an acid stabilizer for diazonium salts in diazo photosensitive layers, but the use of boric acid for diazo photosensitive paper applications has not yet been known.

Boric acid is a compound with the molecular formula Na2B4O710H2O, and its aqueous solution is alkaline.Thus, when boric acid is used in the production of diazo-sensitive paper, it is unlikely that a pre-camping reaction between the diazonium salt and the coupler will occur. being sidelined.

In the present invention, by incorporating this boric acid into the precoat layer forming composition, the viscosity of the precoat layer forming composition can be reduced to WJ:! without causing such troubles such as precoupling reactions. This makes it possible to form a uniform and smooth precoat layer even by high-speed coating.

Conventionally, various organic type thinners have been known as thinners for aqueous M1 compositions. However, in the system of an aqueous composition containing a silica-based filler and an organic binder, which is the object of the present invention, boric acid has a significantly superior viscosity-reducing effect compared to these organic-based viscosity-reducing agents. , and this East fact is the first one below.
It will become clear by referring to the table.

Table 1 Additives Distribution uL ■ Poor Ω - Viscosity (cps)
0 7.8 Bora Sand 0.10 5.
0 Organic Thinner A O,15' 7.3 Organic Thinner B O,158,8 Organic Thinner CO,158,8 As the aqueous composition, the base composition described in the Examples described later is used. Using.

(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 includes a paper substrate 1, a precoat layer 2 applied to the surface of the paper substrate, and a precoat layer 2 applied to the surface of the paper substrate. It consists of a photosensitive layer 3 containing a photodegradable diazonium compound provided thereon.

The present invention is characterized in that this precoat layer 2 is formed from an aqueous composition containing a silica filler, a binder, and boric acid.

In this precoat composition, it is the silica filler that acts to increase the specific surface of the photosensitive layer and impart a pigment effect to the dye formed as t; It acts to improve the texture of photosensitive paper and also to improve its copying characteristics.

A preferred silica filler is vapor phase silica, commonly known under the name Aerosil. Vapor-phase silica is amorphous silica with an extremely fine primary particle size, and its specific surface area is as large as 50 g/m2 or more, especially 100 g/m2, and its dispersed particle diameter is generally 0.1 It is in the range of 20 lm to 20 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 is present in the coating liquid in the form of spherical particles with an emulsion size, that is, a particle diameter 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 characteristic, which shows the effect of providing excellent binding properties without impeding the pigment effect, is thought to be due to the fact that even after the pre-coat film is formed, the remains of the emulsion particles remain. It will be done. As a latex type thermoplastic resin binder.

Conventionally known latex or emulsion adhesives 1 For example, polyvinyl acetate latex, vinyl acetate-vinyl chloride copolymer latex, acrylic resin emulsion, styrene-acrylic copolymer emulsion,
Although a vinyl chloride-acrylic copolymer emulsion or the like can be used, the effect of the present invention is remarkable when the present invention is applied to a styrene-acrylic copolymer emulsion.

The amount ratio of silica-based binder to binder can vary over a fairly wide range, but generally speaking, a ton u ratio of 0.1:1 to 10:1 and 0.2:1 to 2:1 is preferred. It is preferable to use it in

If the amount of silica-based filler is less than the F2 range, the above-mentioned effects will be unsatisfactory, while if it is more than the above range, the permeation of the photosensitive composition will increase, and the precoat phase will easily peel off. occurs. On the other hand, if the +7) of this latex resin is less than the above range, the binding of silica particles will be unsatisfactory, and if it is more than the above range, both the pigment effect and the seepage prevention effect will be unsatisfactory. Tend.

This precoat phase forming composition has a solid content concentration of 0.1
Qi is used as an aqueous composition with a weight of 0.5 to 50% by weight, especially 0.5 to 3% by weight, but in the present invention, 0.01 to 1.0% by weight, especially 0.05 to 0. .5 ml contains 1% boric acid. That is, when the content e of boric acid is less than the above range, a satisfactory viscosity reduction effect cannot be obtained in 1 minute, and when it is more than the Hobeiki range, the precoupling between the diazonium salt and the coupler is prevented. This tends to cause defects such as fog.

In the uninvented photosensitive paper, the basis weight of the paper base (paper 880 mm
The weight (Kg) per area of
Even relatively thick materials such as 8 kg can be used for the purpose of the present invention.

To provide a precoat layer on this paper substrate, prepare a coating solution of the above-mentioned composition v4, and apply this coating solution at a coating amount of 0.5 to 4.0 g/rx2 as solid content, especially 1.0 g/rx2. 5
2.0 g/m2 to 2.0 g/m2 using a known L stage, for example, a coating roller, an air knife coater, a burneater, a flade coater, a reverse coater, a hard coater, a spray, a 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.

Next, a known diazo photosensitive layer composition is provided on this precoat layer.

The photosensitive diazonium salt to be contained in the diazo photosensitive layer is a diazonium salt that is photodegradable and capable of being pulled with a coupler used in the diazo copying process under normal development conditions. Either can be used.

As the stabilizer to be contained in the diazo photosensitive layer, any organic acid or inorganic acid such as sulfosalicylic acid,
P-) Luenesulfone, 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, compounding agents known per se, such as wetting agents, stabilization aids, development accelerators, extenders, dispersants,
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! Product diazonium salt 0.1-4.0% coupler
0.1-5.0% acid stabilizer
2 to 10.0% Development accelerator 2 to IO30% Extender 0 to IO90%
Dispersant O to 1.0% dye
0 to 0.003% solvent Remaining amount (2) - component diazo photosensitizer M1 product diazonium salt 0.1 to 4.0% acid stabilizer
2.0 to 10.0% stabilizing agent
0 to 10.0% Extender 〇 to 10.0% Dye 0 to 0.00
3% Solvent Residual Amount The coating tools for the above-mentioned photosensitive compositions differ depending on the type of substrate and development method, but generally the coating amount of the diazonium salt is 0.05 to 0.05%. 2g/m2,
In particular, it may be in the range of 0.075 to 0.15 g/m2.

Image exposure and development of this photosensitive layer can be easily carried out by means known per se, for example by exposing the document to light from a light source such as a fluorescent lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, etc.
On the other hand, for development, dry development using ammonia-steam, semi-dry development or wet development using organic or inorganic m/() can be applied.

The invention is illustrated by the following example.

(Example) As a composition for forming a precoat layer: Borax ・・・・・・・・・・・・・・・・・・
・・・Old・・・・・・・・・ 1.0g-Polyvinyl acetate (Movinyl DC; manufactured by Hoechst Gosei Co., Ltd.) ・・・・・・20g
・Silica (Si02; Aeroseal #200, manufactured by Nippon Aeroseal Co., Ltd.)...3
0 gs# 1801. (Manufactured by Taisei Kayakusha) ・・Own・
・Water was added to 50 g or more of the chemical so that the total amount was lfi. After uniformly dispersing or dissolving the solution with this composition using an ultra-high-speed stirrer, it is made into base paper for photosensitive paper (100 sq. yen, 63 g/
m2) with an air knife coater, the coating amount is 2.0
It was coated with a varnish bead at a rate of 3000 m/hour to give g#+2 and dried to form a precoat layer.

Next, 4-diazo-2,5 dibutoxy-N-phenylmorpholine chloride MZnC:12 was applied as a composition for forming a diazo photosensitive layer on the precoat layer.
・・・・・・・・・・・・13g2-Hydroxy-3-naphtho-N-β-hydroxyethylamide ・・・・・・・・・・・・・・・
・・・・・・12゜citric acid ・・・・・・
・・・・・・・・・・・・・・・ 7g zinc chloride
・・・・・・・・・・・・・・・・・・・・・
1g rice starch ・・・・・・・・・・・・・・・・・・
・・・・・・5g polyvinyl acetate emulsion (Polysol 2NS: manufactured by Showa Kobunshi Kagaku Co., Ltd.) ・・・・・・・・・・・・・・・
・・・・・・ 5g Thiourea ・・・・・・
・・・・・・・・・・・・・・・ 2g Diethylene glycol ・・・・・・・・・・・・ 3g Methylene Blue B Conc ・・・・・・・・・0.12g
A solution made up to a total volume of one coat by adding water was applied uniformly using an air knife coater, and dried to obtain diazo photosensitive paper.

The Jian photosensitive paper obtained as described above was exposed and developed using Copistar ED-800 manufactured by Sanda Kogyo Co., Ltd. As a result, an even i-color image was obtained.

(Comparative Example) 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 using an ED-800 manufactured by Sanda Kogyo Co., Ltd. and developed, resulting in an image with uneven shading in both image and non-image areas. The unevenness in the halftone area is especially noticeable.

(Comparative Example 2) The composition for forming a precoat layer was heated with air in the same manner as in Comparative Example 1.
The coating was applied using a knife coater at a coating speed of 1500 m/hour while adjusting ILII to 2.0 gets2, and dried to form a precoat layer.

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

The resulting diazo photosensitive paper was exposed to light over the original using Copistar ED-800 manufactured by Sanda Kogyo Co., Ltd., and developed, resulting in a uniform image. However, the number of varnish beads in the precoat layer was significantly reduced.

[Brief explanation of the drawing]

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 (2)

[Claims] (1) In a method for manufacturing diazo-sensitive paper, which comprises applying a pre-coat layer on the surface of a paper substrate and then applying a diazo-photosensitive agent layer on the pre-coat layer, the composition for forming the pre-coat layer includes a silica-based filler, A method characterized in that an aqueous composition containing a binder and borax is used. 2. The method of claim 1, wherein the borax is present in an amount of 0.01 to 1.0% by weight of the aqueous composition.