JPS6147404B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a heat-developable photosensitive material, and more particularly to an improved heat-developable photosensitive material containing an organic silver salt suitable for an electrostatic printing master. A large number of printing methods have been known so far, but electrostatic printing constitutes a unique field of printing. Ordinary printing technology is based on selectively adhering ink to the printing master surface according to the uneven surface formed on the printing master surface or the difference in solvent affinity, and pressing paper onto this. I'm there. On the other hand, in the electrostatic printing method, unlike mechanically (or physically) applying ink to a printing master, ink (toner) is applied electrostatically and this is transferred to paper. It is based on This electrostatic printing method is described in, for example, Japanese Patent Laid-Open No. 51-24308. The electrostatic printing master used in the electrostatic printing method described above has a layer mainly consisting of a silver image supported on an insulating medium that has sufficient electrical resistance to hold electrostatic charges, so the image is uneven. Since the surface is smooth and not formed by silver, the image is hardly damaged by mechanical friction during printing, and has excellent durability. It has many excellent features such as its high resolution, excellent resolution due to continuous gradation, and the ability to change optical density according to any continuous gradation, and is useful only in the printing field. There are great expectations in the field of high-speed, multi-sheet copying, and its practical application is desired as soon as possible. Usually, the electrostatic printing master having a layer mainly composed of the above-mentioned silver image is obtained by imagewise exposure and development of a silver salt photosensitive material.
Among them, the so-called silver liquid can be formed by dry processing, so the adoption of photosensitive materials containing organic silver salts, catalytic amounts of silver halide, an insulating medium, and reducing agents as necessary for the organic silver salts is important. This is effective in terms of the simplicity of image creation. Such photosensitive materials are called heat-developable photosensitive materials, and conventional ones include, for example, Japanese Patent Publication No. 43-4924, Japanese Patent Publication No. 7782-1978, and Japanese Patent Publication No. 47-11113. It is described in publications and has been commercially available. However, all of these conventional heat-developable photosensitive materials are those in which the final visible image is directly formed on the heat-developable photosensitive material, and are so-called heat-developable photosensitive materials for copying. Proposed Japanese Patent Application Publication No. 1973
- From the practical point of view, it cannot be used as it is for forming an electrostatic printing master as described in No. 24308. Therefore, the present applicant has improved the heat-developable photosensitive material for electrostatic printing master in the previous Japanese Patent Application Laid-open No. 51-24308 so that it has the characteristics as an electrostatic printing master and is highly practical and commercially viable. This is an improvement. The present invention is based on the results of thorough examination from various aspects of such a heat-developable photosensitive material as a photosensitive material for forming an electrostatic printing master, and after discovering that there are points that need further improvement. Through intensive research, we have succeeded in developing a heat-developable photosensitive material that can be used as an electrostatic printing master that fully satisfies the requirements for an electrostatic printing master both technically and commercially. In other words, as an electrostatic printing master, it has to have a high acceptance potential in non-silver image areas, good electrostatic charge retention, high electrostatic contrast, and low residual potential in silver image areas. For example, toner performance conditions such as excellent toner image quality (sharpness), printing durability, electrical fatigue resistance, and sufficient mechanical strength are required, and in addition to these conditions, static The electroprinting master can be formed simply and easily in a short time, the production of the heat-developable photosensitive material itself can be done easily, the cost is low, no special treatment is required for transportation, and distribution is easy. The present invention provides a heat-developable photosensitive material for electrostatic printing masters that satisfies the above-mentioned conditions and has excellent properties that have extremely high commercial value. The main purpose is to provide Another object of the present invention is to provide a novel heat-developable photosensitive material. The heat-developable photosensitive material of the present invention, particularly the heat-developable photosensitive material suitable for electrostatic printing, is characterized by containing at least one compound represented by the following general formula [] as (c) a reducing agent. As a result, the electrostatic properties are significantly improved, and the performance as a master for electrostatic printing is dramatically improved. General formula [] In the formula, R ₁ and R ₂ represent a tertiary alkyl group (e.g., t-butyl group, t-amyl group, t-octyl group, etc.), and R ₃ and R ₄ represent a substituted or unsubstituted alkyl group. (For example, methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, t-butyl group, benzyl group, P-chlorobenzyl group, etc.). n is an integer from 1 to 4. Specific examples of the compound represented by the general formula [] are as follows. Compound example The heat-developable photosensitive material of the present invention can be reacted with at least (a) an organic silver salt, (b) a photosensitive silver halide, or the above (a) organic silver salt to form a silver halide on a support. It has a structure in which a coating layer consisting of a halogen compound, the above-mentioned (c) reducing agent, and (d) binder is provided in a single layer or a laminated structure. This heat-developable photosensitive material is produced by, for example, mixing and dispersing an organic silver salt and a halogen compound in a binder, which is an insulating medium, and coating the mixture on a suitable support to form an organic silver salt layer. A reducing agent layer is prepared by mixing a reducing agent with a binder made of a resin such as cellulose acetate using an appropriate solvent and applying the mixture to the surface of the organic silver salt layer previously formed to form a reducing agent layer. be done. Further, the above-mentioned reducing agent may be used together with an organic silver salt, and in this case,
There is no problem even if a reducing agent layer is provided separately. Alternatively, the above-mentioned reducing agent may be incorporated by coating the organic silver salt layer before or after image exposure. The organic silver salt (a) preferably used in the present invention is disclosed in Japanese Patent Publication No. 4924/1983,
Examples include silver salts and organic silver complex salts such as organic acids, mercapto compounds, and imino compounds described in Publication No. 90306, etc.; For example, silver salts of long-chain fatty acids such as silver behenate, silver stearate, silver palmitate, silver myristate, silver laurate, silver oleate, and silver hydroxystearate are suitable. Specific examples of the halogen compound (b) preferably used in the present invention include the following inorganic halogen compounds and halogen-containing organic compounds. (1) Inorganic halogen compound The preferred inorganic halogen compound is one represented by the general formula MXm. In the formula, X represents halogen (Cl, Br, I), and when m is 2 or more, X may be the same type of halogen or different halogens. M is hydrogen, calcium, strontium,
Cadmium, chromium, rubidium, copper, nickel, magnesium, zinc, lead, platinum, palladium, bismuth, thallium, ruthenium, gallium, indium, rhodium, beryllium, cobalt, mercury, barium, silver, cesium, lanthanum,
Indicates iridium, aluminum, etc., where m is 1 when hydrogen is present, and when M is a metal, it indicates its valence. Furthermore, silver chlorobromide, silver chlorobromoiodide, silver bromoiodide,
Silver chloroiodide is also suitably employed. (2) Halogen-containing organic compounds Carbon tetrachloride, chloroform, trichloroethylene, triphenylmethyl chloride, triphenylmethyl bromide, iodoform, bromoform, cetylethyldimethylammonium bromide, etc.
The above-mentioned halides (1) or (2) may be used alone or in combination of two or more,
The amount added is usually 1 mol or less, preferably 10 ^-1 mol to 10 ^-5 mol, per 1 mol of organic silver salt. In the present invention, more preferable results can be obtained by using other reducing agents as shown below in combination with the compound represented by the above-mentioned general formula [] as the reducing agent (c). These reducing agents include aminophenols, phenylenediamines, polyhydroxybenzenes, ascorbic acids, 3-pyrazolidones, oxytetronic acids,
Contains hydroxytetronimides or reductone reducing agents. Representative examples of these include hydroquinone; methylhydroquinone; chlorohydroquinone; bromohydroquinone; catechol; pyrogallol; methylhydroxynaphthalene; aminophenol; 2,2'-methylenebis(6-t-butyl-
4-methylphenol); 4,4'-butylidenebis(6-t-butyl-3-methylphenol);
4,4'-bis(6-t-butyl-3-methylphenol);4,4'-thiobis(6-t-2-methylphenol); 2,6-di-t-butyl-p-
Cresol; 2 _× 2′-methylenebis(4-ethyl-
6-tert-butylphenol); phenidone; metol; 2,2'-hydroxy-1,1'-binaphthyl;6,6'-dibromo2,2'-dihydroxy-
1,1'-binaphthyl; bis(2-hydroxy-1
-naphthyl)methane, 2,2'-methylenebis-
(6-t-butyl-p-cresol) and mixtures thereof. The content of the reducing agent represented by the above general formula [] used in the heat-developable photosensitive material of the present invention is determined appropriately depending on the desired properties, but is generally based on 1 mole of organic silver salt. The amount is 5 mol or less, preferably 1 mol or less, most preferably 1 mol to 10 ^-4 mol. Furthermore, when it is contained in combination with other reducing agents, it can be contained in the same amount as above as the total amount of reducing agents. At this time, it is preferable that the proportion of the reducing agent represented by the above general formula [] is 10% by weight or more based on the total amount of the reducing agent. Furthermore, in the heat-developable photosensitive material for electrostatic printing master of the present invention, a toning agent is used to control the color tone of the resulting image, and a toning agent is used to impart stability to the image, which is particularly important during long-term storage. A light stabilizer for preventing so-called fogging due to light during storage of heat-developable photosensitive materials before image formation and for preventing temporal changes in images due to fogging after image formation; Components such as sensitizing dyes and development accelerators may be added in necessary amounts depending on the desired properties of the heat-developable photosensitive material. Preferred binders used in the present invention, particularly those exhibiting insulating properties, include gelatin, polyvinyl butyral, polyvinyl acetate, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, polyvinyl alcohol, ethyl cellulose, methyl cellulose, benzyl Cellulose, polyvinyl acetal, cellulose propionate, cellulose acetate propionate,
Hydroxyethyl cellulose, ethyl hydroxy cellulose, carboxymethyl cellulose, polyvinyl formal, polyvinyl methyl ether,
Examples include styrene-butadiene copolymer and polymethyl methacrylate, and two or more of these compounds may be used as a mixture if necessary. The amount of these binders is determined as desired, but is usually 0.02 to 20 parts by weight, preferably 0.1 to 5 parts by weight, per 1 part by weight of the organic silver salt.
Parts by weight are preferred. Additionally, aluminum, copper, and
Metal plates such as zinc and silver or metal laminated paper,
Art paper, paper treated to prevent solvent from penetrating inside, paper treated with conductive polymer, synthetic resin film mixed with surfactant, metal, metal oxide or metal halide adhered to the surface by vapor deposition method Films such as glass or paper, synthetic resin, cellulose acetate film, polyethylene terephthalate film, polycarbonate film, and polystyrene film can be used. Insulating materials such as glass, paper, and synthetic resin may also be used. In particular, when used by wrapping it around a drum, it is preferable to use a suitable flexible metal sheet, paper, or other conductive material so that it can be wrapped around the drum. Art paper is particularly suitable as such material because of its properties as a support and its low cost. When providing a conductive layer on the surface of a synthetic resin film, paper, or other non-conductive support, either the organic silver salt layer side of the support or the side opposite to the layer may be selected depending on the purpose of use. When the conductive layer is in direct contact with the organic silver salt layer, it is preferable to select a material for forming the conductive layer that does not react with the organic silver salt. When employing a conductive support, it is generally one whose surface resistivity is smaller than the non-silver image area when forming an electrostatic printing master, that is, 10 ⁹ Ω·cm or less, preferably 10 ⁵ Ω·cm. Any material may be used as long as it is less than cm and does not react with the organic silver salt. In order to form an electrostatic printing master using the heat-developable photosensitive material of the present invention, in a structure in which a reducing agent layer is provided on an organic silver salt, a latent image is usually formed by imagewise exposure. It is then thermally developed to form a silver image and used as a master. Furthermore, in the case of heat-developable photosensitive materials that do not contain a reducing agent in advance, an electrostatic printing master can be formed by adding a reducing agent before or after image exposure, forming a latent image, and performing heat development. Ru. The reducing agent may be added by immersing the heat-developable photosensitive material before image exposure in a liquid containing the reducing agent at the time of use, or by applying the reducing agent before image exposure. A reducing agent may be applied by a similar treatment before post-thermal development. Alternatively, instead of the above-mentioned dipping method, a reducing agent solution dispersed in cellulose acetate etc. using an appropriate solvent may be applied onto the organic silver salt layer by methods such as brush coating, coating, doctor blade, spraying, etc. good. It is advantageous if the reducing agent layer is peeled off from the surface of the organic silver salt layer after heat development, since so-called fogging due to the action of the remaining reducing agent can be prevented. Since the heat-developable photosensitive material of the present invention has particularly excellent electrostatic properties, the use thereof has been described in detail by citing only an example of an electrostatic printing master. The uses of the material are:
It is not limited to being used in the heat-developable photosensitive material for forming the electrostatic printing master mentioned above,
It can be used as a heat-developable photosensitive material for forming a visible image by sequentially carrying out conventional image exposure and heat development, or as other optical recording materials. Hereinafter, the present invention will be explained according to examples. Example 1 25 g of 90 mol% silver behenate ^* , 120 g of methyl ethyl ketone and 120 g of toluene were mixed and dispersed for over 72 hours by ball milling. Thereafter, 56.5 g of polyvinyl butyral (20 wt % ethyl alcohol solution) was added and thoroughly mixed to prepare a polymer dispersion of an organic silver salt. To the thus prepared polymer dispersion were added a 200 mg/25 ml solution of calcium bromide in methyl alcohol, 2.5 g of phthalazinone, 120 mg/25 ml of mercury acetate, and a methyl alcohol solution, followed by thorough mixing.
Next, this polymer dispersion was applied onto art paper using a coating rod in a dark place so that the film thickness after drying was 8 μm to form an organic silver salt layer. [ ^* 90mol% silver behenate is a silver salt of organic acid.
The number of moles is divided by the number of moles of the organic acid plus the number of moles of the silver salt of the organic acid, and this value is multiplied by 100. This means the case of acid silver. The mol% of the organic acid silver salt in the following examples shall have the above meaning. ] Next, 1.5 g of the exemplified compound (1), phthalazinone
0.3 g of cellulose acetate (10 wt% acetone solution), 30 g of acetone, and 9 mg of the following compound as a sensitizing dye were mixed to prepare an overcoat layer solution. This overcoat layer solution was coated on the organic silver salt layer in a dark place so that the film thickness after drying was 4 μm to obtain a heat-developable photosensitive material for forming an electrostatic printing master (Sample 1). Next, this photosensitive material was exposed to light for 20 seconds using a tungsten light source (2500 lux) through a positive image, and then exposed to light for 130 seconds using a roller heating device.
A negative printed visible image was obtained by heat development at 50° C. for 5 seconds and was used as a master for electrostatic printing. Next, after applying a +6 KV corona discharge uniformly to the electrostatic printing master, the negatively charged toner was developed by a magnetic brush development method, and a positive toner image was obtained. When a transfer paper was placed over this toner image and the aforementioned corona discharge was applied from the transfer paper side, a clear transferred visible image was obtained. By repeating this charging and development transfer, the number of transfers increases.
Even after 1000 times or more, no deterioration was observed on the master surface, and no deterioration in the quality of the transferred image was observed. Furthermore, no deterioration of the resulting transferred image was observed even after long-term use. As a result, it was recognized that this was an excellent master for repeated printing. Furthermore, since the silver image exhibits faithful reproducibility with respect to the original image, an electrostatic charge image corresponding to the original image was formed, and it was observed that the toner image also became a faithful photographic image. When we measured the electrostatic properties of this master for electrostatic printing, we found that the charging potential difference (electrostatic contrast) between the image area (silver image area) and the non-image area (non-silver image area) was 700V, and the remaining It turns out that the potential is very small. Next, we measured the maximum blackening reflection density (Dmax) of the image area of the master.
It showed 1.65. Furthermore, when the blackening reflection density (fog density) of the non-image area on the transfer paper with the transferred image was measured, it was 0.20, which was a very small value. From the above measurements, it was found that the heat-developable photosensitive material for forming an electrostatic printing master in this example had excellent image properties and formed an excellent master for electrostatic printing that had good printing durability and was durable for practical use. Examples 2 to 5 The above-mentioned exemplified compound (1) was replaced with the above-mentioned exemplified compound (1) as a reducing agent component in the overcoat layer solution used when creating the heat-developable photosensitive material for electrostatic printing master used in the above-mentioned Example 1. Compound (1) - denoted as "A" - and 2,2
A heat-developable photosensitive material for electrostatic printing masters was prepared in the same manner except that methylenebis(6-t-butyl-P-cresol) -denoted as "B"- was used in combination at the mixing ratio shown in Table 1. It was created. This heat-developable photosensitive material was subjected to image exposure and heat development in the same manner as in Example 1 to prepare an electrostatic printing master. Next, electrostatic properties were measured using the same method. These results are shown in Table 1.

[Table] As can be seen from Table 1, an excellent electrostatic printing master could be prepared using the heat-developable photosensitive material of the present invention. Example 6 An organic silver salt layer-forming composition A and an overcoat layer-forming composition B shown below were prepared according to the procedure of Example 1,
It was further coated on art paper to obtain a heat-developable photosensitive material for forming an electrostatic printing master. Composition A: 80mol% silver caprate 10g methyl ethyl ketone 30g, toluene 30g polyvinylbutyral (10wt% ethyl alcohol solution) 60g CaBr ₂ 60mg N-bromoacetamide 50mg 2,3-dihydroxy-5-hydroxy-
1,4-phthalazinedione 1g Composition B: Exemplary compound (2) 0.8g Cellulose acetate (10wt% acetone solution)
10g Acetone 30g 3,3'-diethyl-2,2'-thiacarbocyanine iodide 8mg Next, the various properties of this photosensitive material as a master for electrostatic printing were investigated in the same manner as in Example 1. Like No. 1, this was a heat-developable photosensitive material for forming an electrostatic printing master that provided an excellent electrostatic printing master. Example 7 The heat-developable photosensitive material for electrostatic printing masters of Example 1 was prepared using the same method except that the exemplified compound (4) was used in place of the exemplified compound used to create the photothermographic material for electrostatic printing masters. After creating a developable photosensitive material, an electrostatic printing master was prepared. The electrostatic properties were measured using the same method as in Example 1.
Almost similar results were obtained. As is clear from Examples 1 to 7, improved electrostatic properties can be obtained by using the compound represented by the general formula [] as a reducing agent. The present invention has the features described in the claims, and its embodiments are as follows. (2) The above (c) reducing agent is A heat-developable photosensitive material according to claim 1. (3) The above (c) reducing agent is A heat-developable photosensitive material according to claim 1. (4) The above (c) reducing agent is A heat-developable photosensitive material according to claim 1. (5) The above (c) reducing agent is A heat-developable photosensitive material according to claim 1. (6) A heat-developable photosensitive material containing at least one compound represented by the general formula [] and at least one other reducing agent as the reducing agent (c). (7) The heat-developable photosensitive material according to item 6, which contains at least one compound represented by the general formula [] as the reducing agent (c) in an amount of 10% by weight or more based on the total amount of the reducing agent. (8) The other reducing agent is aminophenols,
The compound according to item 6, which is at least one compound selected from the group consisting of phenylene diamines, polyhydroxybenzenes, ascorbic acids, 3-pyrazolidones, oxytetronic acids, hydroxytetronimides, and reductone-based reducing agents. Heat-developable photosensitive material. (9) The heat-developable photosensitive material according to claim 1, wherein the organic silver salt (a) is a long-chain fatty acid silver salt. (10) The heat-developable photosensitive material according to claim 1, wherein the organic silver salt (a) is silver behenate. (11) The heat-developable photosensitive material according to claim 1, wherein the binder (d) is an insulating binder. (12) The heat-developable photosensitive material according to claim 1, wherein the heat-developable photosensitive material is a heat-developable photosensitive material for electrostatic printing masters.

Claims (1)

[Scope of Claims] 1. On a support, at least (a) an organic silver salt, (b) a photosensitive silver halide, or a halogen compound capable of reacting with the (a) organic silver salt to form a silver halide;
In a heat-developable photosensitive material in which a coating layer consisting of (c) a reducing agent and (d) a binder is provided in a single layer or a laminated structure, at least one of the compounds represented by the following general formula [] as the (c) reducing agent is used. A heat-developable photosensitive material characterized by containing one of the following. General formula [] (In the formula, R ₁ and R ₂ represent a tertiary alkyl group. _{R 3} and R ₄ represent a substituted or unsubstituted alkyl group. n is an integer of 1 to 4.)