JPS582831A - Two-component diazo copying material - Google Patents

Abstract

PURPOSE:To obtain the titled copying material giving a copied image which disappears with the passage of time by forming a decoloring agent layer contg. a reducing agent or an oxidizing agent, an intermediate layer of an alkali soluble resin having a carboxyl group, and a photosensitive layer on a support. CONSTITUTION:A support is coated with a decoloring agent layer contg. an org. or inorg. reducing agent such as hydroquinone or an oxidizing agent such as p- nitrosodimethylaniline, an intermediate layer of an alkali soluble resin having >=1 carboxyl group such as casein, and a photosensitive layer contg. a diazo compound such as 4-diazo-1-dimethyl-aminobenzene, a coupling component such as resorcin and a Ca salt such as CaSO4 as principal components. The resulting copying material is exposed to ultraviolet light to form a latent image, and by development in an alkali atmosphere a copied image is obtd. The image part of the copied image is decomposed by reduction or oxidation with the reducing agent or the oxidizing agent which seeps slowly through the intermediate layer softened during the development, and the image disappears.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to diazo copying materials, and more particularly to diazo copying materials in which copy images disappear over time after use. It concerns a diazo copying material suitable for obtaining so-called erasable copies.

Conventionally, known copying methods include diazo copying methods, wet or dry electrophotographic copying methods, and the like.

A copy made using this method of table copying has its contents,
Particularly in cases where confidentiality is required, it is necessary to dispose of the data in such a way that it cannot be restored after use. Usually, for this purpose, the material is finely chopped using a shredder or the like, but this is time consuming and labor intensive, and an improvement has been desired.

Therefore, the present applicant previously proposed a diazo copying material in which a reducing agent or an oxidizing agent is contained between the support and the photosensitive layer so that the image gradually disappears as the copy is used up. However, this product is limited by the shelf life (particularly the raw shelf life) of the copying material (referred to as raw copying material) before copying.
However, when copying is attempted after long-term storage, the reducing agent or oxidizing agent has already penetrated into the photosensitive layer and decomposed the diazo compound, making it difficult to obtain copies with high image density.

Therefore, it is an object of the present invention to provide a two-component type diazo copying material for erasable copying which improves the above-mentioned drawbacks and has excellent shelf life. a decolorizing agent layer containing either an inorganic reducing agent or an oxidizing agent; an alkali-soluble resin intermediate layer having at least one carboxyl group; a diazo compound;
A two-component diazo copying material characterized in that a coupling component and a photosensitive layer containing a calcium salt as a main component are sequentially provided. The main points are as follows.

During storage before copying, the alkali-soluble resin in the intermediate layer is hardened by reaction with the calcium salt in the photosensitive layer, so that the reducing agent or oxidizing agent in the decolorizing agent layer does not enter the photosensitive layer. leaching.

Prevent migration completely. As a result, raw storage stability is greatly improved, and there is no possibility that the diazo compound in the photosensitive layer decomposes before copying and causes a decrease in image density, unlike in the past. In order to obtain a copy using such a two-component diazo copying material of the present invention, the original is usually placed on the photosensitive layer of the copying material, exposed to ultraviolet light to form a latent image, and then placed in an alkaline atmosphere. Develop it below to obtain a copy image. The thus obtained copy image is then treated with a reducing agent or an oxidizing agent that gradually leaches out through the alkali-soluble resin intermediate layer that is softened in an alkaline atmosphere during development, and the image area (diazo compound and kaglar) is removed. The azo dye-forming region (formed by the coupling reaction) is reductively decomposed or oxidatively decomposed and disappears. In this way, the copied image automatically disappears, and the so-called 1
You will get a “disappearing copy”.

The diazo copying material of the present invention will be described in detail below.As the support, any support that can be used in general diazo copying materials such as paper, cloth, and film can be used.

Examples of organic or inorganic oxidizing agents and reducing agents include the following.

Organic oxidizing agent: p-nitrosodimethylaniline, lead tetraacetate, hexamine, organic peroxide, N-chloroacetamide Inorganic oxidizing agent dichromate, permanganate, copal)
(III) salt, manganese dioxide, molybdenum oxide, selenium dioxide, sulfated organic reducing agent: hydroquinone, catechol, pyrogallol, alkyl triphosphate, thioglylic acid, thioglycol Inorganic reducing agent: tin (1) salt, hypochlorite, thiosulfate,
Chromium (■) salt, zinc powder Examples of alkali-soluble resins in which at least one cal has a xyl group include casein, alginic acid, pectic acid,
Colladan, gelatin, rosins, gum arabic, calgoxymethylcellulose, polyacrylic acid, vinyl acetate-crotonic acid copolymer, vinyl acetate-maleic acid copolymer, vinyl acetate-acrylic acid copolymer, styrene-vinyl acetate -Acrylic acid copolymer, vinyl chloride-styrene-
Examples include acrylic acid copolymers, etc., and partial alkali metal salts thereof.

The calcium salt used in the photosensitive layer of the present invention is an acid salt soluble in an acidic aqueous solution, such as calcium chloride, calcium nitrate, calcium bromide, calcium iodide, and hydrates thereof.

As the diazo compound used in the photosensitive layer of the present invention together with the calcium salt, any conventionally known diazo compound can be used.

Specific examples include 4-dibucy 1-2 methyl (5) aminobenzene, 4-diazo-1--)ethylaminobenzene, 4-diazo-1-dipropylaminobenzene,
4-Diazo-1-methylbenzylaminobenzene, 4-
Diazo-1-dibenzylaminobenzene, 4-diazo-
1-ethylhydroxyethylaminobenzene, 4-diazo-1-diethylamino-3-methoxybenzene, 4-
Diazo-1-dimethylamino-2-methylbenzene, 4
-Diazo-1-benzoylamino-2,5-jethoxybenzene, 4-diazo-1-morpholinobenzene, 4-
Diazo-1-morpholino-2,5-shedoxybenzene, 4-diazo-1-morpholino-2,5-dibutoxybenzene, 4-diazo-1-anilino-benzene, 4-diazo-1-dimethylaminotercal Gexibenzene,
Chlorides such as 4-diazo-1-toluylmercapto-2,5-shedoxybenzene, 4-diazo-1,4-methoxybenzoylamino-2,5-jethoxybenzene and zinc chloride, cadmium chloride or tin chloride. There are double salts, sulfuric acid, 4-fluoroboric acid acid salts, etc., but of course (6
) Not limited to these.

As the coupling component that causes a coupling reaction with the diazo compound to form an image, any of the following components used in general copying materials can be used.

resorcin, phloroglucin, 2,5-dimethyl-4-
Molpolytu methylphenol, 3-hydroxycyanoacetanilide, /4'sulfoacetanilide, 1-benzoylamine-8-hydroxynaphthalene-3,6-
Disulfonamide, 2,2-dihydroxynaphthalene,
Sodium 2,7-dihydroxynaphthalene 7-3,6-disulfonate, Sodium 2,3-dihydroxy-6-sulfonate/, Sodium 2,5-dihydroxynaphthalene-6-sulfonate, Sodium 1-hydroxynaphthalene-4 -sulfonic acid ida, 1-amino-3-hydroxynaphthalene-3,6
-Disulfonamide, naphthol As, naphthol AS
-D, 2-hydroxynaphthalene-3-piguanide,
2-hydroxynaphthoic acid morpholinoglopyramide,
2-Hydroxynaphthoic acid ethanolamide, 2-hydroxynaphthoic acid-N-nomethylaminoglopyramide hydrochloride, 2,4.2',4'-tetrahydroxydiphenyl, 2#4#2'#4'-tetra Hydroxydiphenyl sulfoxide etc.

The diazo copying material of the present invention further contains the following binder resins, preservability improvers, antioxidants, solubilizers, coatability improvers,
As the image density improver and surface property improver, any of those used in general diazo copying materials can be used.

Binder resin: Water-soluble and emulsion polymeric substances such as soluble starch, casei/polyvinyl acetate, polyvinyl alcohol, hydroxyethyl cellulose, and polyacrylic acid derivatives Preservation improver: 1. Naphthalene, sodium monosulfonate, naphthalene -Sodium disulfonate, naphthalene-trisulfone jl? −)! Aryl sulfonic acid salts such as Jum, sodium benzenesulfonate, and sodium p-toluenesulfonate 2; Metal salts such as aluminum sulfate, cadmium sulfate, magnesium sulfate, cadmium chloride, zinc chloride, stannic chloride, and magnesium chloride 3; Organic and inorganic acid antioxidants such as sulfosalicylic acid, citric acid, tartaric acid, acetic acid, oxalic acid, boric acid, phosphoric acid, pyrophosphoric acid, malic acid, and maleic acid; Reducing compound solubilizers such as thiourea and urea : Caffeine, theophylline Coating property improver: Saponin, other surfactant substances, methanol, ethanol, inglonomer alcohol, etc. Image density improver Inorganic or organic fine particles such as Nisilica, starch, clay, resin, etc. Surface property improver: Polyethylene , solid wax, rough-in, carnauba wax, or other wax-like substances to improve the slippage of the copying material surface.

(9) To prepare the diazo copying material of the present invention using the above components, each layer component is dissolved or dispersed in an appropriate solvent such as water or an organic solvent according to a conventional method, and a decolorizing agent layer solution is prepared. An intermediate layer liquid and a photosensitive layer liquid may be prepared, and the obtained liquids may be sequentially applied onto a support and dried.

In order to form a copy image using the diazo copying material thus obtained, a latent image is formed on the surface of the photosensitive layer by the usual exposure method, and then the latent image is exposed under an alkaline atmosphere. When developed, a clear image that disappears over time is obtained.

As the developing solution used in the development of the present invention, a commonly used developer for two-component diazo copying materials containing an inorganic or organic alkali agent is used. Inorganic alkali agents include alkali or alkaline earth metal hydroxides, carbonates,
Borate, sinate, organic alkaline agents such as amines or alkali or alkaline earth metal fatty acid salts,
Amino acid salts etc. can be used. The above components are uniformly dispersed and mixed in water or a water-organic solvent mixture to prepare a developer solution (l
O) Adjust. Examples of organic solvents include polyhydric alcohols, polyhydric alcohol ethers, polyhydric alcohols, and mixtures thereof. In the case of mixed solvents, water increases the solubility of the alkaline agent. , and has the effect of improving color development.On the other hand, the organic solvent has the effect of promoting the diffusion of the developer, reducing the amount of developer applied, and obtaining a semi-dry copy.

To carry out development using the above-mentioned developer, apply a very small amount of the developer to the surface of the exposed photosensitive layer, for example, a rubber roll transfer method used in general offset printing. Preferably, this is carried out by a semi-dry development method in which a layer of liquid is deposited, or a wet development method in which a small amount of developer (approximately 10 g or less) is deposited by a sponge roll coating method.

Examples will be described below. In the Examples, all values are % by weight.

Example 1 A decolorizing agent layer containing a lower G+JL reducing agent was applied to white base paper for diazo copying using a wire bar and dried (adhered, and then an intermediate layer containing an alkali-soluble resin having the following formulation was applied using a wire bar). and dried.

(Amount of adhesion: 1.5 Vr?) Furthermore, a photosensitive layer liquid having the following formulation was applied thereon using a glass doctor and dried. (Deposition amount: 08 g/r?) The diazo copying material of the present invention thus obtained is designated as Sandal (a).

Sample 3) was prepared in exactly the same manner as above except that 3 g of calcium chloride was removed from the photosensitive layer solution. Two-component diazo copying material sample prepared in this way (a)
, (b) with the original, and a commercially available semi-dry developing copying machine, Recopy 5, containing an alkaline organic solvent developer having the following composition.
After exposure using D-205, semi-dry development (developer adhesion amount 1.59/rr?) resulted in 0, (b)
A bright blue image is obtained in an almost dry state,
The image density after 10 minutes of image formation was measured using a Macbeth densitometer manufactured by Macbeth Co., Ltd. (hereinafter, all image density measurements were performed using this densitometer).
The sample (,) is 1.15, and the sample 佽) is 1.13.
Met.

Developer (13) (water
sgFurthermore, in order to find out whether this image disappeared over time, we measured the image density while leaving this copy under normal conditions.We obtained the results shown in Table 1, and found that all samples did not disappear over time. It was confirmed that it disappears with

Table 1 In order to investigate the raw storage properties of these samples (a) and (b), a forced storage test* was conducted for 24 hours in a desiccator adjusted to 50°C and 50% RH, and the samples were tested using the same method as described above. When an image was formed and the image density was measured 10 minutes after the image density reached almost saturation, the sample (,) was 1,
09, sample (b) was 0.75. When this density was compared with the image density when an image was formed without performing the above-mentioned forced storage test (14), the results shown in Table 2 were obtained, and the sample (,) of the present invention was compared with the sample (b). It was found that the difference in image density before and after the test was extremely small, and the product had excellent shelf life.

* Equivalent to 6 months of storage under normal environment 2 Example 2 The two-component diazo copying material sample (, ) of Example 1 was
Using a commercially available wet development copying machine, Ricopy Hi-Start 205, containing a developer with the following composition, overlay it on a suitable original image,
Wet development after exposure (developer adhesion amount 8, !9/rr?
') A bright blue image was obtained. The image density at 10 minutes after image formation was 1, the image density at 20 minutes was 0.35, and the same image disappearing effect as in Example 1 was confirmed.

This copying material was subjected to a forced storage test in the same manner as in Example 1, and the image density was measured for 10 minutes after image formation.1.
The difference in concentration from 1.2° when 19 is not stored under the strong 1st system is -
It was confirmed that the raw storage stability was excellent at 0.01.

Developer Example 3 A decolorizing agent layer containing an oxidizing agent having the following formulation was applied to white base paper for diazo copying using a wire spar and dried.
rr? ) Furthermore, an intermediate layer containing an alkali-soluble resin having the following formulation was applied thereon using a wire coater and dried.

(Amount of adhesion 2p back) -・ Shimizu

100 CC. Further, a photosensitive solution having the following formulation was applied thereon using a glass doctor and dried. (Amount of adhesion: 0.71/rr?) The two-component diazo copying material (17) thus prepared was exposed and developed in the same manner as in Example 1, and a bright black image was obtained. Image density is determined by water removal for 10 minutes.
22, but it decreased to 0.38 after 240 minutes, indicating a color erasing effect.

Furthermore, when this copying material was exposed and developed in the same manner as in Example 2, the same effects were confirmed.

This copying material also had excellent shelf life.

Example 4 A decolorizing agent layer containing a reducing agent having the following formulation was applied to a transparent resin-treated base paper using a wire spar and dried (coating amount: 1, 2 g/W?
) Furthermore, an intermediate layer containing an alkali-soluble resin having the following formulation was applied thereon using a wire coater and dried.

(Deposition amount: 21 W) (18) Further, a photosensitive layer liquid having the following formulation was applied thereon using a glass doctor and dried. (Amount of adhesion: 1.o Vrr?) When the two-component diazo copying material thus prepared was exposed and developed in the same manner as in Example 1, a bright brown image was obtained. This image also had excellent UV blocking properties and could be used as a second original image.

The image density was 15 after 10 minutes of water removal, but it became 0 after 240 minutes.
．． 26, indicating a decoloring effect.

Furthermore, this copying material had excellent shelf life.

Patent application human body system company Ricoh (19) Agent Patent Attorney Hidetaku Komatsu

Claims (1)

[Claims] A decolorizing agent layer containing either an organic or inorganic reducing agent and an oxidizing agent on a support, an alkali-soluble resin intermediate layer having at least one carboxyl group, a diazo compound, a coupling component, and a calcium salt. A two-component diazo copying material characterized by sequentially providing a photosensitive layer containing and as main components.