JPS6292890A - Thermal transfer copying method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a thermal transfer type copying method using a heat sublimable or heat vaporizable azo dye as a transfer dye.

[Prior art]

Traditionally, there has been a strong demand for color copying, and much research has been devoted to the development of this color copying system. However, in the case of the conventional color copying system, (1) it takes a long time to copy and is not suitable for making large numbers of copies; (2) The image is rough and the gradation is poor; (3) The device is complicated and costly; at the same time, the cost per copy is also high. It is requested.

The present inventors have developed a new color copying method that overcomes the drawbacks of the conventional methods using a principle different from that of conventional color copying methods. A photosensitive material containing silver is subjected to a series of treatments consisting of image exposure, development, and dye bleaching to create a color master sheet for thermal transfer having a positive image made of an azo dye. A thermal transfer copying method was proposed (Japanese Patent Application No. 59-234474) characterized in that a receiving sheet is placed on top of a positive image and a transferred image made of an azo dye is formed on the receiving sheet by thermal transfer.

Simply put, the principle of this color copying method is a combination of the principle of producing color photographs using the silver dye bleaching method and the principle of thermal transfer copying using an azo dye as a transfer dye. It has a structure in which a cyan red photosensitive layer, a magenta green photosensitive layer, and a yellow blue photosensitive layer containing a heat sublimable or heat vaporizable azo dye together with silver halide are laminated on the body in that order. is used.

By the way, in such light-sensitive materials, the azo dye used in combination with silver halide absorbs the light that should expose the silver halide, resulting in a problem in that the photosensitivity of the light-sensitive materials is significantly reduced. Conventional.

Various optical sensitizing dyes have been proposed to increase the spectral sensitivity of silver halide, but none have been satisfactory as optical sensitizing dyes that make silver halide sensitive to red light. Moreover, when increasing the amount of each photosensitive layer deposited in the photosensitive material described above, the light intensity of the light incident on the red photosensitive layer forming the bottom layer becomes weaker due to scattering, etc., resulting in insufficient sensitivity of the red photosensitive layer. The problem becomes more serious.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermal transfer copying method that compensates for the lack of sensitivity of the red light-sensitive layer found in the light-sensitive materials and provides a clear color image.

〔composition〕

According to the present invention, a cyan red photosensitive layer, a magenta green photosensitive layer, and a yellow blue photosensitive layer containing a heat sublimable or heat vaporizable azo dye together with silver halide are formed on a transparent support. A photosensitive material having a structure in which layers are sequentially laminated is subjected to normal image exposure from the front side and image exposure from the back side to light in the red region through the transparent support, and then subjected to development and dye bleaching treatment. A color master sheet for thermal transfer having a positive image made of an azo dye is prepared by using the above method, and a receiving sheet is overlaid on the positive image of the color master sheet for thermal transfer and thermal transfer is performed, thereby transferring the color from the azo dye onto the receiving sheet. A thermal transfer copying method is provided, which is characterized by forming a transferred image.

Next, the thermal transfer type color copying method of the present invention will be described in detail.

(a) Color master sheet (Figure 1) In the color copying method of the present invention, a photosensitive material containing a heat-sublimable or heat-vaporizable azo dye to which spectrally sensitized silver halide has been added is used as a color master sheet. use FIG. 1 shows an example of the layer structure of this color master sheet. In Figure 1,
(2) indicates a yellow dye layer and a blue sensitive layer, Mu indicates a magenta dye layer and a green sensitive layer, and C indicates a cyan dye layer and a red sensitive layer. are laminated to form a photosensitive layer X.

(b) Exposure step (Figure 2) This step is a step in which the color master sheet is exposed to direct imaging light or reflected imaging light from the original to form a latent image in the photosensitive layer X. .

In the present invention, this exposure step consists of two steps, the first step is normal image exposure from the front side of the support, and the second exposure is from the back side of the support. ,
That is, this is image exposure using light in the red region through the light-transmitting support 1. When performing the second exposure, the imaging light is a mirror image of that for the first exposure. This second exposure improves the problem of insufficient sensitivity of red-sensitive MC. A diagram explaining the exposure principle in this case is shown in FIG. In FIG. 2, W indicates white light, BL indicates blue light, G indicates green light, R indicates red light, and BR indicates black light. The position of the latent image formed in the photosensitive layer is determined by the tone of the exposed color;
In the case of white light (υ), blue photosensitive layer (Y), green photosensitive layer (M)
In the case of blue (BL), it is formed in the blue photosensitive layer (Y), in the case of green (G), it is formed in the green photosensitive layer (M), and in the case of blue (BL), it is formed in the green photosensitive layer (M); In the case of No. 10, the latent image is formed on the red photosensitive layer (C), while on the other hand, in the case of black, no latent image is formed on the photosensitive layer.

(C) Black-and-white development step (Figure 3) This step is a step in which the exposed color master sheet obtained in the exposure step is subjected to black-and-white development, and the latent image formed in the photosensitive layer Developed as an image. FIG. 3 shows an explanatory diagram of the principle of black and white development. In FIG. 3, the X mark indicates the developed blackened silver image. The reaction formula for this black and white development is as follows.

Ag" X, -+D P -) Ag+X-+OX I
DP: Developer OX■: Oxidized product of developer (d) Dye bleaching process (Figure 4) This process uses the blackened silver obtained in the black and white development process as a catalyst, and blackens with a strongly acidic solution. proportional to the amount of silver.

This is a process in which the azo dye in the area where blackened silver is present is decomposed and reductively bleached. FIG. 4 shows a diagram explaining the principle of dye bleaching. In FIG. 4, the white area including the X mark without diagonal lines indicates the dye bleached area.

The reaction formula for this dye bleaching is as follows.

4Ag+RN=NR'+48"→4Ag"+RNH2+R'NH2RN=NR'
: Azo dye (0) fixing step (Figure 5) In this step, the decomposed dye obtained in the dye bleaching step is treated with a fixing solution, unnecessary silver halide is removed, and a positive image of the azo dye is created. This is the process of obtaining

FIG. 5 shows an explanatory diagram of the principle of the fixing process. In FIG. 5, the completely white area without diagonal lines indicates the bleached area of the dye that has been fixed. The color master sheet obtained in this way is a color positive image (
However, as shown in FIG. 5, depending on the exposure to the light of the color tone shown in FIG. 2, the image becomes white (W), blue (81, green(
G), giving an image with red (R) and black (BR) tones.

(f) Thermal transfer step (FIG. 6) This step is a step in which the azo dye image formed on the color master sheet of the positive image obtained in the fixing step is transferred onto the receiving sheet. FIG. 6 shows a diagram explaining the principle of this thermal transfer process. In FIG. 6, A indicates a color master sheet, and 2 indicates a receiving sheet. In this process, the receptor sheet (2) is placed on the color master sheet (A) and heated by applying thermal energy (H) to sublimate or vaporize the azo dye present on the color master sheet. Transfer onto sheet (2). The thermal transfer copy obtained in this manner has a color image corresponding to a color original, and FIG. 7 shows a cross-sectional view of the color copy. In this FIG. 7, BR, R, G, BL and J indicate the transferred images formed on the receiving sheet corresponding to the color master sheet (A), and are respectively black, red, green, blue and A white transfer image is shown. That is, the color of the image formed on the receiving sheet consists of a mixture of azo dyes transferred from the color master sheet.

In the present invention, the structure of the color master sheet as shown in FIG. silver dy
It is possible to apply color photography techniques based on the basic principle of ``e bleach process''. For example, the color master sheet can be used for yellow, magenta,
It can be created by coating and drying a spectrally sensitized silver bromide emulsion containing azo dyes showing each color of cyan to form each dye layer. A subbing layer can be provided between the two. Further, if necessary, an intermediate layer may be provided between each dye layer to separate each dye layer, and these intermediate layers may also contain a filter dye and an oxidizing agent.

Further, as a binder for the emulsion used in the present invention, various parent colloids including gelatin are used, and in this case, the gelatin is not limited to gelatin.

Derivative gelatin is also included, and as derivative gelatin,
Included are reaction products of gelatin and acid anhydrides, gelatin and isocyanates, or reaction products of gelatin and compounds having active halogen atoms.

In addition to the gelatin and derivative gelatin described above, polyvinyl alcohol, colloidal albumin, agar, gum arabic, dextran, alginic acid, cellulose derivatives such as cellulose acetate hydrolyzed to an acetyl content of 19 to 26%, polyacrylamide, Imidized polyacrylamide, casein, e.g.
Vinyl alcohol polymers containing urethane carboxylic acid groups or cyanoacetyl groups such as vinyl alcohol-vinyl cyanoacetate copolymers, polyvinyl alcohol/polyvinylpyrrolidone, hydrolyzed polyvinyl acetate, silkworm white matter or saturated acylated silkworm white matter and monomers having vinyl groups. Polymers obtained by polymerization of , polyvinylpyridine, polyvinylamine, polyaminoethyl methacrylate, polyethyleneimine, etc. can be used.

Further, it is preferable to add additives to each layer as necessary, and thiazoline, benzotriazole, acrylonitrile, and benzophenone compounds can be used as ultraviolet absorbers, and azaindenes, 1-riazoles, and tetrazoles can be used as stabilizers. etc., imidazolium salts, tetrazolium salts, polyhydroxy compounds, etc. are used.

Further, as a hardening agent, an aldehyde type, an aziline type, an inoxazole type, a vinyl sulfone type, an acryloyl type, an albodiimide type, a maleimide type, a methanesulfonic acid ester type, a triazine type, etc. are used.

Further, development accelerators such as benzyl alcohol and polyoxyethylene compounds, image stabilizers such as chroman, coumaran, bisphenol and phosphite esters, and gelatin plasticizers such as glycerin and glimal compounds are used. In addition, styrene-sodium maleate copolymer and alkyl vinyl ether-maleic acid copolymer are used as thickeners.

In addition, sensitizers include noble metal sensitizers such as water-soluble gold salts, water-soluble platinum salts, water-soluble palladium salts, water-soluble rhodium salts, and water-soluble iridium salts, sulfur sensitizers, selenium sensitizers, boramine, and dichloromethane. In addition, as a spectral sensitizer for silver halide, cyanine dyes such as zeromethine dyes, monomethine dyes, dimethine dyes, trimethine dyes, or merocyanine dyes can be used as azo dyes. Can also be used in combination with a suitable pyrazine, quinoxaline or phenazine (e.g. 2,3
-dimethylquinoxaline, 2,3-diaminophenazine, 2-hydroxy-3-aminophenazine, etc.), anthraquinone sulfonic acid, pyrazine-2,3-dicarboxylic acid, pyrazine, 2,5-dimethylpyrazine, 2,6-dimethylpyrazine , diphenylpyrazine, acylaminopyrazine, etc. are also preferably used. Regarding photosensitive materials in such a silver dye bleaching method and the formation of positive images using the same, there are conventionally known documents, such as Makoto Kikuchi's "Photo Chemistry" (published by Kyoritsu Shuppan KK, Kyoritsu Zensho 21, 1968). Edition) Paragraphs 292-293, "Chemistry of Photography" by Akira Sasai (Shashin Kogyo Robansha 1978 edition) Paragraphs 293-297; A.
Meyer.

J. Phot, Sci., 20, 81 (1972)
; L, F, A, Mason.

Pho7ographic Processing
chemistry, FocalPress,
London, 1966, P, 275, etc., as well as Japanese Patent Publication No. 43-24743 and Japanese Unexamined Patent Publication No. 1973
It is described in Japanese Patent Application Laid-Open No. 46-68808, Japanese Patent Publication No. 43-16185, and many other patent documents.

The present invention is characterized in that a receptor sheet is placed over a color master sheet having a positive image that is a mirror image of a color original, and heated, thereby transferring the azo dye image on the color master sheet onto the receptor sheet. However, in this case, in order to make this thermal transfer process practical, the selection of the azo dye is important, and in the case of the present invention, the heating temperature is 80 -
It is advantageous to use azo dyes which exhibit thermal sublimation or thermal vaporizability at 250 DEG C., preferably from 120 DEG to 180 DEG C.

In the case of the present invention, it is preferable to use an azo dye having a structure represented by the following general formula.

In the general formula, x, ■ and 2 represent the following substituents.

h3 (In the above formula, A and B are HlOH, CQ, 'Br, N
o 2, CN.

So 2Ct(3, CnH2n+ 1 (n = 1
-5), etc., and D indicates H2CO2, etc.) (In the formula, R,, R2 are H, CnH2n+1 (n is 1 to
(an integer of 5), (CH2)nOH (n represents an integer of 1 to 5, etc.) Z; HlOH, CQ, Br, NO2, CN,
5O2CH3゜Coz CH3, CnH2n+ t
(n is an integer of 1 to 5) Examples of the above-mentioned dyes include the following compounds.

The dye can be used by adding a surfactant or a dispersant in an amount of 0.01 to 1.0 weight relative to the dye and thoroughly mixing and dispersing the dye in water. In this case, the particle size of the dispersed dye is about 0.1 to 6.0 μm, preferably 0.1 to 1 μm.
．． 0 μm is good.

Plain paper can be used as the receiving sheet used in the present invention, and in this case, the plain paper has one smooth surface, for example, a smoothness of 20 to 150, preferably,
The use of between 50 and 150 is advantageous. Further, as the receptor sheet, it is also preferable to use a surface-treated sheet, for example, a sheet having a receptor layer that is dyeable to an azo dye. In this case, the resin used to form the receptor layer may be any heat-softening and melting resin that can be easily dyed with sublimation or vaporizable dyes, and is well known in the field of sublimation printing. A variety of polymers are used. Examples of such materials include amino alkyd resins, polyamides, polyurethanes, polyvinyl chloride, polyvinyl acetate, polyesters,
Acrylic resin.

Examples include acetal resin, polyvinyl alcohol, polyvinylidene chloride, polyvinyl acetal, polystyrene, polycarbonate, and epoxy resin. In the case of the present invention, it is preferable to use a resin having a softening point of 60 to 120°C. As the organic filler, various fine polymer particles are employed, but the particle diameter is preferably 10 μl or less. Examples of polymers constituting the organic filler include methylcellulose, ethylcellulose, polystyrene, polyurethane, urea/polymarine resin, melamine resin, phenol resin, iso(or diiso)butylene/maleic anhydride copolymer, styrene/maleic anhydride. Acid copolymer, polyvinyl acetate, polyvinyl chloride, vinyl chloride/vinyl acetate copolymer, polyester, polyacrylic acetate ester,
Examples include polymethacrylic acid ester, styrene/butadiene/acrylic copolymer, and the like. Further, as the base sheet, paper, synthetic paper, plastic film, metal foil, etc. can be used. When thermal transfer is performed using such a receiving sheet, the surface of the resin forming the receiving layer of the receiving sheet is softened and melted, and the vaporized dye enters the molten resin and is dyed. Therefore, after the transfer is completed, one dye molecule is incorporated into the resin, so the fading resistance and storage stability of the obtained dye image are significantly improved.Also, a large amount of dye is adsorbed, and the density and sharpness of the image are also extremely high. Excellent. The dyeable resin is usually applied onto the base sheet in the form of an aqueous emulsion containing an organic filler, but of course it can also be applied by a hot melt method or the like depending on the case. The ratio of resin and organic filler used is 179 by weight.
It is best to set the ratio to ~9/1. In this receiving sheet, the organic filler mixed with the resin of the receiving layer exhibits the effect of facilitating peeling of the receiving sheet from the transfer sheet after completion of transfer. The lower the softening point of the resin in the receptor layer, the better the colored image it will give, but on the other hand, the lower the softening point of the resin, the stronger the bond between the transfer layer and the receptor layer, making it extremely difficult to peel the receptor sheet from the transfer sheet. do. The use of organic fillers solves these peeling problems. In addition, the organic filler prevents the heat transferred from the transfer layer to the receptor layer from escaping toward the substrate.
It also shows the effect of increasing the effective utilization rate of heat that is effectively utilized for softening and melting the resin. The dye image formed on such a receiving sheet has excellent fading resistance and storage stability, and is extremely excellent in density and sharpness. In addition, other surface-treated sheets used as receiving sheets in the present invention include:
Examples include those in which a resin layer containing fillers such as calcium carbonate, silica, and kaolin is provided on a base sheet. As the resin in this case, various resins as mentioned above can be used.

Further, as the receiving sheet in the present invention, it is preferable to use a dyeable film having a heat-sensitive adhesive surface on one side in combination with a support sheet.

In this case, the dyeable film may be any film as long as it has dyeability to sublimated or vaporized dyes, and in general, plastic films are suitable.6 In the case of the present invention, in particular, Those having a softening point in the temperature range of °C are preferable, such as polyester film, polysulfone, polyvinyl chloride film, polyamide film, etc., and the thickness thereof is usually 20 to 150 μm,
Preferably it is 30 to 80 μm. In the present invention,
A heat-sensitive adhesive layer is formed on one side of this dyeable film, and the film is processed into a heat-sensitive adhesive surface. The heat-sensitive adhesive layer in this case can be formed by a conventionally known method, for example, by applying a coating agent commonly used as a hot-melt adhesive. Examples of such coating agents include those based on ethylene/vinyl acetate copolymer, polyvinyl acetate, polyvinyl butyral, polyethylene, and polyamide, and those based on ionomer resins are also used. be done. The heat-sensitive adhesion temperature of these coating agents is generally 60 to 120°C, but any coating agent may be used as long as it produces adhesive properties when heated below the melting point of the dyeable film. Further, the heat-sensitive adhesive layer can be formed not only by using the above-mentioned coating agent but also by dry laminating a film of the above-mentioned coating resin, such as a polyethylene film. This heat-sensitive adhesive layer can be formed on a part or the entire surface of the dyeable film. The type of support sheet used in combination with the dyeable film is not limited, and any type can be used. For example, various types such as paper, synthetic paper, plastic film, metal foil, etc. can be used.

When performing thermal transfer using a receptor sheet in which a dyeable film and a support sheet are combined as described above, the dyeable film and support sheet are placed in that order on the positive image side of a color master sheet having a positive image. , and heat transfer is performed by overlapping the dyeable film so that the heat-sensitive adhesive surface provided on the dyeable film is in contact with the support sheet. Through such thermal transfer, the azo dye that has been thermally sublimated or thermally vaporized from the surface of the color master sheet is dyed onto the dyeable film and at the same time gives an image.
The dyeable film is thermally bonded to the support sheet, and as a copy, the support sheet and the dyeable film are integrated to obtain a sheet having an azo dye image on one surface (the surface of the dyeable film).

In the present invention, when thermal transfer is performed by overlapping a color master sheet having a positive image made of an azo dye and a receiving sheet, a transfer mechanism consisting of a pair of heating rolls and a color master sheet support drum is used. The sheet is wound and fixed on the surface of the support drum, and the receiving sheet is continuously fed from one direction between the support drum and the heated roll. When the receiving sheet is supplied in this manner, the receiving sheet is overlapped with the color master sheet wound around the supporting drum between the supporting drum and the heating roll, and is simultaneously thermo-pressed and bonded to the positive image on the color master sheet. The image is transferred onto a receiving sheet and successive color copies thereof are obtained. That is, similar to a normal copying machine, by using one color master sheet, a large number of color copies can be obtained in succession. In this case, the number of color copies obtained is proportional to the amount of azo dye formed as a positive image on the color master sheet used. That is, in the color master sheet shown in FIG.

By increasing the layer thickness of the azo dye layers indicated by K and C, a larger number of color copies can be obtained. The thickness of each azo dye layer Y2M and C is generally 0.
．． 5 to 3.0 μm, preferably about 0.5 to 2.0 μm6 [Effect] The color copying principle of the present invention is as described above, and the copying machine has a simpler structure than conventional color copying. This makes it possible to obtain color copies with high resolution, high gradation, high sensitivity, and at high speed. According to one aspect of the invention, therefore, the color copies obtained have the advantage of being low cost.

Furthermore, in the present invention, the exposure process is divided into two, and in addition to the normal exposure, auxiliary exposure with light in the red region is performed through the support, thereby solving the problem of insufficient sensitivity of the red-sensitive layer.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.

Example A: Preparation of color master sheet (1) Preparation of photosensitive material A photosensitive material having three color azo dye layers was prepared by using a boloimide film as a support and sequentially forming each layer shown below on it. It was created.

1st layer (bottom layer): Silver bromide emulsion layer 2 in red sensitized polyvinyl alcohol containing a cyan azo dye of Sumikaron Blue 5E-RF (manufactured by Sumikaron Chemical Co., Ltd.)
Layers: Polyvinyl alcohol layer 3rd layer: Silver bromide emulsion layer in green-sensitized polyvinyl alcohol containing a magenta azo dye of Sumikaron Red E-3BR (manufactured by Sumikaron Chemical Co., Ltd.) 4th layer: Polyvinyl Alcohol layer 5th layer: A yellow filter layer containing a dye represented by O 6th layer: A silver bromide emulsion layer in polyvinyl alcohol containing a yellow azo dye of TS-Yellow 115 (manufactured by Sumitomo Chemical Co., Ltd.) The individual dye layers each contain an amount of silver bromide corresponding to 0.5 g of dye and 5.0 to 5.2 g of silver.

(2) First Exposure The photosensitive material was exposed to white light through a transparent original having each color of red, green, and blue.

(3) Second Exposure A transparent original is placed on the back side of the photosensitive material after the first exposure, and a Y, M filter (Kodak Safelight Filter No. LA) is placed between the original and the photosensitive material. (4) Development, bleaching and fixing The exposed photosensitive material was developed with the following developer at 20° C. for 4 minutes.

<Developer> P-methylaminophenol hydrochloride 1g hydroquinone 3II anhydrous sodium sulfite 13 Potassium bromide
l H anhydrous sodium carbonate
26〃P-methylsulfonamide-ethyl-phenylhydrazine 2〃Water was added to the above-mentioned platform to make the total amount into one layer.

After washing with water, it was treated with the following dye bleaching solution at 24°C for 5 minutes.

<Dye bleaching solution> Water 50
0m Q Sulfamic acid 135
g Succinic acid 2 oll Thiourea 3 Ethylene thiourea 227/Potassium bromide
151! 2-amino-3-hydroxyphenazine 3II 1g Add water to the above mixture and prepare I
I named it Q.

After washing with water, the sample was treated with the following bleach-fix solution used in a conventional color development method at 24° C. for 4 minutes.

<Bleach-fix solution> Ethylenediaminetetraacetic acid sodium salt 2g Ethylenediaminetetraacetic acid iron acetate salt 60//Sodium carbonate (
monohydrate) 4 u sodium sulfite (
Anhydrous) 2 o ammonium thiosulfate 60 no! Disodium phosphate salt 12 Potassium iodide 5 Water was added to the above table to make the total amount IQ.

In this way, a color master sheet having red, green, and blue positive images on its surface was obtained.

B: Preparation of receptor sheet Polyester resin emulsion 40 parts by weight (resin concentration 50%) Styrene resin fine particles 20 Water
40 The above composition was stirred and mixed for 1 hour, coated on high-quality paper with a basis weight of 50 g/rrr, and dried to a dry weight of 4 g/rrr to prepare a receptor sheet.

C: Thermal transfer The above-obtained color master sheet was overlaid with the receiving sheet, and this was passed between heated rolls to perform thermal transfer. As a result, a clear cyan color image was formed on the receiving sheet.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an example of the layer structure of a color master sheet, Fig. 2 is an explanatory diagram of the exposure principle, Fig. 3 is an explanatory diagram of black and white development,
FIG. 4 is an explanatory diagram of the dye bleaching principle, FIG. 5 is an explanatory diagram of the fixing principle, FIG. 6 is an explanatory diagram of the thermal transfer principle, and FIG. 7 is a cross-sectional diagram of a color copy.

Claims (1)

[Claims] (1) A cyan red photosensitive layer containing a heat sublimable or heat vaporizable azo dye together with silver halide, a magenta green photosensitive layer, and a yellow blue photosensitive layer are laminated in this order on a transparent support. A photosensitive material having a structure is subjected to normal image exposure from the front side and image exposure from the back side to light in the red region through the transparent support, and then subjected to development and dye bleaching treatment to form an azo dye. By creating a color master sheet for thermal transfer having a positive image consisting of a positive image, and performing thermal transfer by overlaying a receiving sheet on the positive image of the color master sheet for thermal transfer, a transferred image consisting of an azo dye is formed on the receiving sheet. A thermal transfer copying method characterized by forming.