EP0015879A2 - Receiving elements containing a water-permeable binder as dyestuff mordant, and photographic materials containing the same - Google Patents

Abstract

1. A receiving element for transferred dyes which comprises a support having coated thereon a mordant layer containing a water-permeable binder in which are dispersed particles of an anionically charged, water-insoluble copolymer, the copolymer used consisting of a) a monomer which when homopolymerised yields a water-insoluble polymer, and b) a monomer which contains a sulfonate group and which when homopolymerised yields a water-soluble polymer.

Description

The present invention relates to receiving elements for transferred dyes, especially cationic dyes.

Receiving elements for transferred dyes are used in photography in dye transfer processes by diffusion, where dyes are formed in a layer of the photographic material and diffuse into a layer of a dye receiving element where they are pickled. In such a process, the dye is formed imagewise in a layer of the photographic material and diffuses imagewise into the receiving element. There it is pickled to form a dye image. In such a process, the receiving element can first be connected to the rest of the photographic material and, after the dye image has formed therein, be separable therefrom. However, if the receiving element is not bonded to the rest of the photographic material, it is kept in surface contact with it during use, so that the diffusing dye from the photographic material can diffuse into the receiving element. The receiving element is then separated from the photographic material.

Receiving elements are also used in certain dye soaking processes in which a dye is transferred imagewise, for example via an image template or from a gelatin image matrix, to a receiving element. Such a suction process can be used in the production of color positive film copies.

Receiving elements for transmission processes by diffusion and also suction processes usually contain a carrier on which a dye mordant in a binder has been eaten. Most of the mordants used to date are polymeric substances which are soluble in water or organic solvents and are usually cast with the binder as a solution. The formation of a stable dye / mordant complex in such polymers relies on electrostatic and hydrophobic bonding. These are usually ionically charged polymers of complicated structure, which are produced as solution polymers. Since the polymer must not diffuse in the dye-receiving layer of the receiving element, solution polymers of sufficiently high molecular weight must be produced. However, difficulties have arisen. If the polymerization is carried out at temperatures above 80 ° C. in order to obtain material of higher molecular weight, the polymer crosslinks in many cases and therefore cannot form a real solution suitable for pouring onto the support of the receiving element. Suitable solution polymers for pickling cationic dyes would be those which contain a sulfonate or sulfate group. However, such solution polymers are used to increase viscosity in casting compounds, e.g. Sodium cellulose sulfate as well as polymers as in U.S. Patent 3,022,172. Aqueous solutions of such solution polymers therefore have such a high viscosity that they cannot be used for the production of pickling layers.

It has now been found a receiving element which can be used for pickling dyes transferred thereon and which does not make use of solution polymers as pickling agents.

The present invention accordingly relates to a receiving element for transferred dyes which consists of a carrier a pickling layer containing a water-soluble binder cast thereon, in which particles of an anionically charged, water-insoluble copolymer are dispersed, which consist of at least one monomer providing a water-insoluble polymer in the homopolymerization and at least one monomer containing a sulfonate group and providing a water-soluble polymer in the homopolymerization will be produced.

It goes without saying that further components can be present in the polymer, for example units which are derived from a monomer which gives a water-soluble polymer during homopolymerization but does not contain a sulfonate group. Afterwards, however, such units do not offer any advantages. It is also possible to use two or more monomers which give a water-insoluble polymer in the homopolymerization. Two or more sulfonate group-containing monomers can also be used to prepare the polymer.

Acrylic and vinyl monomers are preferred as the monomers providing a water-insoluble polymer in homopolymerization.

sowie Vinylmonomere der allgemeinen Formel

worin R Wasserstoff, Methyl oder Halogen, R₂ Alkyl oder Aryl und R₃ Aryl, Acyloxy oder Cyan ist.Particularly suitable monomers are acrylic monomers of the general formula

and vinyl monomers of the general formula

wherein R is hydrogen, methyl or halogen, R _{2 is} alkyl or aryl and R _{3 is} aryl, acyloxy or cyan.

Monomers in which R _{2 is} alkyl with 1 to 5 carbon atoms or phenyl and R _{3 is} phenyl, acyloxy with 1 to 4 carbon atoms or cyan and R _{1 has} the meaning given above are particularly preferred.

Examples of particularly suitable monomers of the formulas (1) and (2) are styrene, acrylonitrile, vinyl acetate, methyl methacrylate and ethyl acrylate.

As monomers containing a sulfonate group, acrylic monomers are preferred because of their easy copolymerizability.

worin R₄ Wasserstoff oder Methyl, Q ein zweiwertiger organischer Rest und M ein Alkali- oder Ammoniumkation ist.Particularly suitable monomers are acrylates or methacrylates of the general formula

wherein R _{4 is} hydrogen or methyl, Q is a divalent organic radical and M is an alkali or ammonium cation.

The divalent organic radical Q is preferably an alkylene group having 2 to 6 carbon atoms, which is optionally interrupted by further divalent groups such as -0-, -S- or -NH-.

worin R₄, Q und M die oben angegebenen Bedeutungen haben.Other suitable monomers are acrylamides and methacrylamides of the general formula

wherein R ₄ , Q and M have the meanings given above.

Preferred divalent organic radicals are alkylene groups and interrupted alkylene groups, for example:

Copolymers suitable for use in the pickling layer of the receiving element according to the invention are, for example, copolymers of styrene and the sodium 2-acrylamido-2-methylpropanesulfonate, styrene and sodium vinyl sulfonate, acrylonitrile and sodium allyl sulfonate as well as styrene and 2-sodium sulfoethyl methacrylate.

In general, no more than 5 to 20% by weight of the copolymer should be derived from the monomer containing the sulfonate group; the resulting copolymer would otherwise no longer be water-insoluble. Insoluble in water here means that the polymer is soluble to less than 0.1 g / liter of water at 20 ° C.

Gelatin is preferred as the binder for the anionically charged copolymer.

Other suitable water permeable binders include casein, albumin, polyvinyl alcohol, polyacrylamide and polyvinyl pyrrolidone.

The copolymers can be prepared using conventional initiators, e.g. 2, 2'-azobis (2-methylpropionitrile), 4,4'-azobis (4-cyanovaleric acid), potassium persulfate and ammonium persulfate.

The receiving element according to the invention can be used in a photographic color transfer process by diffusion. The receiving element can represent a part of the photographic material that includes at least one light-sensitive layer. The photographic material is usually exposed, if necessary through the base of the receiving element, if it is transparent. After that the Developer solution introduced into the photographic material; this develops the photosensitive material and at the same time effects an image-wise transfer of at least one diffusible dye released in the photographic material. This migrates to the receiving element, where it is pickled by the charged polymer in the receiving layer. In some processes where such photographic material is used, the receiver layer remains attached to the rest of the photographic material. In other processes, the receiving element is stripped from the rest of the photographic element after the dye has been stripped. In other methods, the receiver layer is not bonded to the rest of the photographic material, but may be attached to it along an edge, for example. After imagewise exposure of the photographic material, the receiving element is brought into extensive contact with the rest of the photographic material. Developer solution is allowed to penetrate and at least one dye is transferred from the photosensitive part of the photographic material into the receiving element. After the dye has been transferred, the receiving element can be removed from the rest of the photographic material.

The invention thus furthermore relates to light-sensitive photographic materials which contain a receiving element as defined above.

The receiving element according to the invention can also be used in a single-eye transmission method, for example where a gelatin relief image is formed on a matrix. This relief image is stained with a cationic dye and the matrix is then pressed onto the receiving element so that the colored gelatin is in extensive contact with the receiving layer. The dye is transferred to the receiving layer and pickled there.

Various other suction methods in which the receiving element according to the invention can be used are known, including a method in which the dye is transferred to the receiving layer through a stencil or a screen-printed image.

The receiving elements according to the invention can be used in any transmission method for cationic dyes, even complete coloring of the receiving layer is possible.

In order to make the layer containing the anionically charged polymer translucent, the particle size of the polymer is preferably an average diameter of 1 micron or smaller. The technique for producing particles of this size is well known in the paint and pigment industry.

The solid dispersion of anionically charged polymers used in the pickling layer of the receiving element according to the invention has a number of advantages over the use of similarly used solution polymers. For example, considerably more polymer can be incorporated into the pickling layer than in the production of pickling layers using solution polymers, because solution polymers, when mixed with the water-permeable binder, give casting compositions of very high viscosity which are difficult to cast. If water-insoluble mordants are used, the low molecular weight water-soluble material present in the polymer material can also be washed out quite easily if necessary. This ensures the highest substantivity of the polymer in the water-permeable binder, and this substantivity of the polymer in the pickling layer helps to promote maximum dye absorption and maximum dye density.

Suitable receiving elements contain, cast on a support, a polymer layer cast in gelatin which contains 2 to 50% by weight of polymer, preferably 10-40% polymer. 20-100 mg / dm ² is a suitable gelatin casting weight.

The support for the receiving element can be a film base with a receiving layer cast thereon containing the charged polymer or a paper base with a receiving layer cast thereon. However, any other base usually used as a photographic support can be used, for example glass. If the receiving element is to be used in a suction process to achieve an artistic effect, any type of rigid support such as a metal plate or even wood can be used. It goes without saying that one or more layers can be present between the receiving layer and the base on which it is cast. These can be, for example, substrate layers, neutralizing layers or time control layers.

und weitere wohlbekannte kationische Farbstoffe der Formeln

The cationic dyes, which can serve to illustrate the pickling capacity of the receiving elements according to the invention, include phenosafranin of the formula

and other well known cationic dyes of the formulas

The production of the polymers used according to the invention is described below.

Manufacturing instructions 1 Preparation of a copolymer of sodium 2-acrylamido-2-methylpropanesulfonate and styrene (hereinafter referred to as copolymer I)

2-Acrylamido-2-methylpropanesulfonic acid (5.0 g) and styrene (45 g) are dissolved in N, N-dimethylformamide (150 ml) and 0.3 g of 2,2'-azobis (2-methyl propionitrile) is added. The mixture is heated at 60 ° C. under nitrogen for 24 hours to allow the polymerization to proceed. The solution is then filtered to remove a small amount of insoluble material and evaporated to dryness in vacuo. The dry solid is suspended in 500 ml of n-NaOH by stirring to convert the copolymerized sulfonic acid into its sodium salt. The fine suspension is filtered off and then redispersed in 500 ml of distilled water and stirred for 1 hour. This process is repeated 5 times to remove unpolymerized monomers and homopolymerized sulfonate. The polymer is then dried in vacuo over a drying agent. The final yield shows that 99% of the monomers have reacted to copolymers. From the micro elemental analysis, it follows that the monomer ratio in the finished copolymer is the same as in the original monomer mixture.

Manufacturing instructions 2 Preparation of a copolymer of sodium 2-sulfoethyl methacrylate and styrene (hereinafter referred to as Copolymer II)

2-Sulfoethyl methacrylate (10.0 g) and styrene (40 g) are dissolved in dimethoxyethane (185 ml) and 0.5 g of 2,2'-azobis (2-methylpropionitrile) is added. The mixture is heated to 60 ° C. under N _{2 for} 24 hours. According to preparation instruction 1, the copolymerized sulfonic acid is converted into its sodium salt and the copolymer is purified. A 90% conversion of the monomers into polymer is achieved. The copolymer contains 83% of the calculated amount of polymeric 2-sodium sulfoethyl methacrylate.

Manufacturing instructions 3 Preparation of a copolymer of 2-acrylamido-2-methylpropanesulfonate and acrylonitrile (hereinafter referred to as copolymer III).

2-Acrylamido-2-methylpropanesulfonic acid (10 g) and acrylonitrile (40 g) are dissolved in 600 ml of distilled water and 0.6 g of potassium persulfate and 0.3 g of sodium metabisulfite are added. The mixture is heated at 40 ° C. for 3 hours under nitrogen in order to allow the polymerization to proceed. The copolymer suspension is filtered off and treated in accordance with preparation instruction 1. The conversion of monomer to polymer is 85%. The polymer contains 50% of the theoretical polymeric sodium salt of 2-acrylamido-2-methylpropanesulfonic acid.

The copolymers I, II and III are all largely water-insoluble; their solubility is considerably less than 0.05 - g / liter at 20 ° C.

example

In this example, copolymers I, II and III are tested.

• Ein Topf mit kreisförmigen Boden wird teilweise mit Glaskugeln (von entsprechender Grösse, um die erforderliche Teilchengrösse zu ergeben), dem zu mahlenden festen Polymer (1,5g), Netzmittel (0,02g) und Wasser (25 ml) so gefüllt, dass die Glaskugeln von der Flüssigkeit bedeckt sind. Man rührt das Gemisch mehrere Stunden lang mit einem mechanischen Rührer. Die Grösse der Dispersionsteilchen wird unter dem Mikroskop kontrolliert, bis sie als zufriedenstellend erachtet wird (z.B. kleiner als 1 Mikron mittlerer Durchmesser).

The solid dispersions of the copolymers are produced in the following way:

• A pot with a circular base is partially filled with glass balls (of the appropriate size to give the required particle size), the solid polymer to be ground (1.5 g), wetting agent (0.02 g) and water (25 ml) so that the Glass balls are covered by the liquid. The mixture is stirred with a mechanical stirrer for several hours. The size of the dispersion particles is checked under the microscope until it is considered satisfactory (eg smaller than 1 micron average diameter).

The castings are examined in the following way:

• 2,5 ml 6%-ige entionisierte Gelatine
• 0,4 ml 1,5%-ige Lösung der Verbindung (5) in Wasser
• 0,5 ml 1%-iges Saponin
• 1,0 ml 1%-ige Wässrige Härterlösung
• 4,6 ml Wasser.

A donor layer is poured onto a clear support, dried and incubated overnight. The layer contains:

• 2.5 ml 6% deionized gelatin
• 0.4 ml of 1.5% solution of compound (5) in water
• 0.5 ml of 1% saponin
• 1.0 ml 1% aqueous hardener solution
• 4.6 ml of water.

• 2,25 ml 2%-ige, dispergiertes Polymer wie soeben hergestellt enthaltende Gelatinelösung
• 5,0 ml 6%-ige entionisierte Gelatine
• 0,5 ml 1%-iges Saponin
• 1,0 ml 1%-ige Wässrige Härterlösung
• 1,25 ml Wasser.

A pickling layer is poured onto a clear support, dried and incubated overnight. This layer contains:

• 2.25 ml of 2% dispersed polymer as gelatin solution just prepared
• 5.0 ml 6% deionized gelatin
• 0.5 ml of 1% saponin
• 1.0 ml 1% aqueous hardener solution
• 1.25 ml water.

The visible spectrum of the donor layer is recorded. The receiving element test strip is drawn through a 0.1N sulfuric acid bath (impregnation time approximately 28 seconds). It is then brought into contact with the dry strip of the donor layer and both are passed through a pair of rollers. The touch time (approximately 2 minutes) is measured. The two layers are separated and dried. The visible spectrum of the dye in the receiving layer is measured.

The receiver layer is soaked in 0.1N sulfuric acid for 5 or 6 minutes. Then they are treated with absorbent paper ("blotting paper") to remove excess acid and then dried. The visible spectrum is measured again.

An investigation was carried out in which a receiving layer without mordant was brought into contact with the donor layer and processed as described above. The dye absorption of this layer was 50% and the substantivity of compound (5) was 30%.

Claims (12)

1. receiving element for transferred dyes, consisting of a support with a poured thereon, a water-permeable binder-containing pickling layer in which particles of an anionically charged, water-insoluble copolymer are dispersed, characterized in that a copolymer of at least one in the homopolymerization a water-insoluble polymer delivering monomers and at least one containing a sulfonate group, in the homopolymerization providing a water-soluble polymer. 2. Receiving element according to claim 1, characterized in that gelatin is present as the water-permeable binder. 3. Receiving element according to claim 1, characterized in that the monomer providing a water-insoluble polymer in the homopolymerization is an acrylic monomer of the general formula

or a vinyl monomer of the general formula

is where R _{1 is} hydrogen, methyl or halogen, R _{2 is} alkyl or aryl and R _{3 is} aryl, acyloxy or cyan. 4. receiving element according to claim 3, characterized in that R _{2 is} alkyl having 1 to 5 carbon atoms or phenyl. And R _{3 is} acyloxy having 1 to 4 carbon atoms, phenyl or cyan and R _{1 has} the meaning given in claim 3. 5. Receiving element according to claim 4, characterized in that the monomer providing a water-insoluble polymer in the homopolymerization is styrene, acrylonitrile, vinyl acetate, methyl methacrylate or ethyl acrylate. 6. Receiving element according to one of claims 1 to 5, characterized in that the monomer containing a sulfonate group and delivering a water-soluble polymer in the homopolymerization eun acrylate or methacrylate monomer of the general formula

in which R _{4 is} hydrogen or methyl, Q is a divalent organic radical and M ^{+ is} an alkali or ammonium cation, or an acrylamide or methacrylamide monomer of the formula

wherein R ₄ , Q and M have the meanings given. 7. receiving element according to claim 6 ,. characterized in that Q is an alkylene group. 2 to 6 carbon atoms, which is optionally interrupted by further divalent groups such as -0- or -NH. 8. receiving element according to one of claims 1 to 7, characterized in that the carrier is a film or paper carrier. 9. receiving element for transferred dyes according to one of claims 1 to 8, characterized in that the amount of solid dispersion of the copolymer in the water-permeable binder is 2 to 50 wt .-% copolymer, based on the binder. 10. receiving element for transferred dyes according to claim 9, characterized in that the amount of solid dispersion of the copolymer in the water-permeable binder 10 to 40 wt .-% copolymer, based on the binder. 11. Receiving element according to one of claims 1 to 10, characterized in that it contains a transferred to the polymer-stained, transferred dye. 12. Photographic material, characterized in that it contains at least one light-sensitive layer and, integrated into the photographic material, a receiving element according to one of claims 1 to 11.