US 3834928 A
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United States Patent-" 3,834,928 PROCESS FOR PRODUCING PHOTOGRAPHIC e 1 MATERIAL Sumitaka Tatsuta and Wataru Ueno, Kanagawa, Japan, ilSSlgllOl'S to Fuji Photo Film (10., Ltd., Kanagawa,
apan 7 No Drawing. Filed Dec. 28, 1971, Ser. No. 213,182 Claims priority, application Japan, Dec. 28, 1970,
46/ 120,542 Int. Cl. B41m /14; G03c 1/78 US. Cl. 117-34 8 Claims ABSTRACT OF THE DISCLOSURE w A process for production of a photographic material which comprises the steps of first undercoating an aqueous gelatin solution or a dispersion of gelatin in an organic solvent onto a stretched high molecular weight film having roughened surface, then heat-treating the resultant film at a temperature in the range of from T 40 C. to T +40 C., thereafter applying to the film an emulsion or suspension containing gelatin as a binder. (T being a glass transition temperature of the film-composing resin used.)
i BACKGROUND OF THE INVENTION Field of the invention This invention relates to a process for the production of a photographic material.
Description of the Prior Art velopment a prolonged drying period isneeded for evaporation of devolping liquid, and these elements show poor resistance to water. In order to overcome these defects, paper coated with polyethylene resin, so-called water-proof paper, has recently been employed for photographic purposes. However, water-proof paper is not suited for practical use be- 1 cause defects such as liquid blotting from the paper edge, poor sharpness upon cutting and the need for an added step of coating the paper with the polyethylene resin.
SUMMARY OF THE INVENTION The main object of the invention is to provide a process for producing a new substrate for a photographic material having an excellent bonding strength between the substrate and a photographic gelatino emulsion or suspension layer provided thereon.
7 Another object of the invention is to provide a water- Iesistant photographic material.
These and other objects of the invention will be more fully understood from the following description.
The present invention is characterized by the steps of applying an aqueous gelatin solution or dispersion in an organic solvent as an undercoat to a high molecular weight film having roughened surface, drying the undercoat by heating to a temperature in the range from T -40 C. to T +40 C., then further coating thereon an emulsion or suspension containing gelatin as a binder.
DETAILED DESCRIPTION OF THE INVENTION By the term roughened surface in this invention is meant the surface where a great number of open pores or concaves are present, that is, about 10 -10 pores per 1 cm The pores are formed by the erosion of a solvent or a swelling agent, having 0.1 to in diameter and above 0.1 a in depth. The upper limit of the depth is to such a degree that the form of a support can be maintained, and varies with a number of pores, a diameter of the pores and a thickness of the support. By the presence of pores, the surface is complicatedly porous.
The term T used herein is defined as the glass transition temperature of the high molecular weight film.
The term emulsion or suspension containing gelatin as a binder used herein includes an aqueous emulsion or an aqueous suspension or gelatin which is prepared with or without the addition of a silver halide such as silver chloride, silver bromide, silver chlorobromide or silver iodobromide, a light-sensitive diazo compound, a substance capable of providing centers of development of the image-receiving material used in a silver halide diffusion transfer process, and other substances constituting necessary components, such as a sensitizer, an antifoggant and a wetting agent, etc.
Stretched high molecular weight films having a roughened surface used in the process of this invention may be obtained by stretching a. film previously formed from a high molecular weight polymer either uniaxially or biaxially according to known plastic stretching techniques, and subjecting the resulted stretched film to any of a variety of surface-roughening treatments. In the case of biaxial stretching, the stretchings may be carried out either simultaneously or sequentially.
The method of stretching films and magnification of stretching are conventional and are described in detail in Plastic film edited by Plastic Film Research Association published by GIHO D0 in Japan.
The roughening of the film surface may be effected by contacting the film with an organic solvent capable of dissolving or swelling the resin of the film to thereby swell the film, then further contacting the swollen film with water or another organic solvent incapable of dissolving the film-composing resin but miscible or compatible with the organic solvent used in the swelling step to thereby elTect the roughening of the film surface, as disclosed in the specification of US. Pat. 3,515,567. In this case, the film may be contacted with the solvent by a variety of methods including immersion of the film in the organic solvent, application of the organic solvent with a roll coater, a brush or sprayer.
There may be also used other roughening treatments for example, mechanical abrasion, the addition of a foaming agent capable of generating gas upon heating to thereby cause roughening all over the film or selective dissolution of a third substance which has been admixed in the film structure before forming to thereby generate acoarse,
- 3 roughened surface. Any one of the above-mentioned roughening treatments may be employed in the present invention.
The resin of the film may contain a white pigment such as, for example, titanium dioxide, barium sulfate, calcium sulfate, barium carbonate, lithopone, alumina white, calcium carbonate, silica white and the like, and if desired a colored pigment in an amount of less than 60% by weight based on the weight of the film.
Resins such as polystyrene, polyesters, polycarbonates and 'polyefins generally have excellent water resistance, dimensional stability, stiffness and the like. Accordingly, a film treated as above exhibits superior whiteness and opacity, and therefore is quite desirable for use as a support for photographic materials. On the other hand, since these resins are inherently hydrophobic and chemically inactive, they have the serious problem that when they are coated with a hydrophilic emulsion containing gelatin, the adhesion between the coated tfilm and the support is very poor.
In order to solve the above problems, we, the inventors have already proposed an improved process for enhancing adhesion between a coated layer of a photographic emulsion and a support, which process involves surface activating treatments such as by corona discharge, ozone oxidation and irradiation with ultra violet rays. These treatments, however, had the disadvantage of needing specially designed and complicated apparatus.
According to the process of this invention, satisfactory adhesion can be established between the emulsion coating layer and the support in simple manner using only con ventional emulsion application or coating equipment without the need for any special apparatus.
It has now been found that extremely strong adhesion between the photographic emulsion and the roughened support can be attained by first coating the roughened support obtained according to the manner as described hereinabove with an undercoating liquid comprising a 5-15 by weight aqueous solution of gelatin or a 0.5-5 by weight dispersion of gelatin in an organic solvent, drying the undercoat by heating to a temperature of T 40 C. to T +40 C., and thereafter applying thereonto a photographic emulsion containing gelatin. The reason for limiting the drying temperature to the range of T 40 C., to T +40 C. is that insufficient adhesion is obtained at a temperature below T 40 C. and that poor flatness is obtained with excessive contraction of the support at temperatures above T +40 C.
It is of course possible to ensure good adhesion and satisfactory flatness even at a temperature above T +40 C. so long as the heat treatment is effected while fixing .the support and thereby preventing excessive contraction.
tin undercoat and the drop of surface tension upon heating,'and (2) generation of a so-called anchoring effect due to shrinkage imparted at the nearness of the glass transition point of the biaxially stretched film.
vAs a matter of fact, there is observed a complete ab sence of adhesion between a photographic emulsion and a support when the same undercoat liquid is applied to a non-roughened, transparent high molecular weight resin film followed by drying at an elevated temperature within a range as defined above. In the case the drying treat ment is carriedout at a temperature below T -40 C.,
the adhesion is too small to be available for practical use as a photographic material.
As the dispersion of gelatin in an organic solvent to be used as the undercoat liquid, it is desirable 'tdnse'metfianol as the solvent because of its stability as a dispersant and against the support. The solvent may also contain, if necessary, a solvent capable of dissolving the film resin, for example, in case of using polystyrene as the film resin, tetrahydrofuran, methyl acetate, ethyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl chloride, ethylene chloride, cyclohexane, benzene, dimethyl formamide etc.
The photographic material obtained in accordance with the process of this invention has excellent adhesion between the support and the photographic emulsion coating layer, excellent water-resistance and excellent wet dimensional stability, so that it enables a shortening or speeding up of development, fixation, water rinsing and- -like procedures, most especially the drying period.
The present invention will be explained more fully' and concretely by referring to the following examples; The test of adhesion between the support and the coated layer set forth in the examples was carried out as follows:
(l) Adhesion test for the dry state A cellulose triacetate film 0.14 mm. thick was bonded using an epoxy type resein adhesive onto the coated surface of a sample film prepared by coating a high molecular film with an emulsion containing gelatin as a binder. The bonded film was allowed to stand for 24 hours at. 23 C. and at a relative humidity of 65%, and then cut into rectangular strips of 1 cm. in width and 15 cm. in length. The cellulose triacetate film was then stripped off at .a pulling speed of 7.38 cm. per minute while measuring the force required for stripping by means of a strain gauge.
In the following examples, the term good adhesion refers to the case where the sample has a stripping resistance of greater than 8 g./mm., which is usually sufficient for practical use as a photographic material.
(2) Adhesion test for the wet state EXAMPLE 1 A biaxially stretched polystyrene support0.l mmHin thickness was dipped for 3 seconds in a solvent consisting of 7 parts ethyl acetate and 1 part-ethanol, then dipped for 30 minutes in methanol. The film became white and opaque.
The resultant film having, the thus roughened surface was coated with an aqueous gelatin solution of the following composition: I .7
Gelatin g 1 Formalin (20% aqueous solution) (hardener) c c 4 Water c' 190 The film coated with the above solution was immediately dried at C. for 10 minutes,'then further coated with a silver halide photographic emulsion of the following composition the amount of which is given for'each square meter of the film.
Silver chlorobromide 3.5 Gelatin 13.0 Formalin (hardener) Q 7 r 10.1 Saponin (wetting agent for coating) .03
Water in an amount to make the entire solution to cc.
. .The, .stripping test of the emulsion-coated film showed excellent adhesion at the dry; state of 17 g./mm. and at the wet state of 6 g./mrn. M
On the other hand,only pooradhesion, i.e., an adhesion strength of 1 g./mm. at theldr'y state and nearly zero at wet state was obtained whe'n'anundercoated film similarly prepared was dried in an air stream at room temperature and then'coated?with the above-mentioned photographic emulsion. Moreover, the emuFsion layer did not bond at all to the support and naturally peeled off when the comparative sample was prepared by coating the undercoat liquid onto. a transparent polystyrene film which had not been treated for surface roughening, even upon drying at 80 C. for minutes and further coating with the above-mentioned photographic emulsion.
EXAMPLE 2 In a manner as described in Example 1 an undercoat liquid having following composition was applied to the roughened support.
Gelatin g 4 Water g 10 Methanol cc 500 Formalin (20% aqueous solution) cc 1.5 Salicylic acid (dispersant) g 1.4
The thus undercoated film was immediately dried at 60 C. for 10 minutes, thereafter coated with a liquid capable of forming an image-receiving layer of an imagereceiving material to be used in a silver salt diffusion transfer photography process having the following composition:
G. Gelatin 3 Silver sulfide colloid (developing nucleus) 0.001 "Phenyl mercaptotetrazol (color tone modifier) 0.01 Saponin (wetting agent) 0.02
The stripping test for this image-receiving material showed a stripping strength at the dry state of 18 g./mm. and at the wet state of 5 g./mm. On the other hand, adhesion strength of 3 g./mm. at the dry state and 1 g./mm. at the wet state was obtained for another sample prepared by coating the undercoat liquid followed by drying in air at room temperature.
EXAMPLE 3 A polystyrene sheet containing 22% by weight of titanium dioxide particles was biaxially stretched at 120 C. in both lateral and longitudinal directions at an elongation of 1.5 times, respectively, to produce a white polystyrene support of a thickness of 0.1 mm. This polystyrene support was dipped in methyl ethyl ketone for 3 seconds and dried in an air stream for 10 seconds, then dipped in methanol for 30 seconds to give a white and roughened polystyrene support containing titanium dioxide. This support was coated with the undercoat liquid described in Example 1, allowed to stand at 5 C. for 10 minutes for setting, then dried in air at 80 C. for 20 minutes. This film was coated with a silver halide color photographic emulsion having the following composition per square meter of the film.
Silver chlorobromide 3.0 Gelatin 3.5
An aqueous gelatin dispersion containing benzoylaceto-2-chloro-5-dodecyloxycarbonyl anilide (yellow coupler) prepared as disclosed below 14.0
Polyvinyl pyrrolidone (molecular weight: 200,000) 0.7
The result of the stripping off test on the above film coated with the color emulsion showed a good adhesion strength in both the dry and wet state, i.e., of a level required for color photographic material, that are 17 g./ mm. and 5 g./mm. in respective states.
The abovernentioned dispersion was prepared by mixing 1 part of 5% by weight aqueous solution of alkylben- Zene sulfonic acid, 10 parts of 10% by weight gelatin aqueous solution, 1 part of dibutylphthalate, 1 part of the above mentioned coupler, 2 parts of ethyl acetate and 0.5 part of methanol solution of 20% by weight anionic active agent, while vigorously stirring.
On the other hand, the undercoat layer Was peeled off naturally when the undercoated film was dried at room temperature by an air stream after setting for 10 seconds at 5 C.
EXAMPLE 4 A polycarbonate film 0.2 mm. thick which had been uniaxially stretched at 190 C. to an elognation of 1.8 times was dipped for 3 seconds in dimethyl formamide and then for another 30 seconds: in methanol to give a whitened film having a roughened surface. This film was coated with the aqueous gelatin solution of Example 1 then heat-treated at 150 C., to dry it for 2 minutesjOnto the resultant film there was coated the silver halide photographic emulsion used in Exampe 1.
The result of the stripping-off test in dry state showed extremely firm adhesion between the emulsion layer and the support with the complete absence of peeling-01f. On the other hand, a stripping strength of at most 10 g./ mm. was obtained when the silver halide photographic emulsion was coated onto a roughened polystyrene film after it had been coated with the above aqueous gelatin solution and dried at room temperature in an air stream.
What is claimed is:
1. A process for the production of a photographic material which comprises the steps of (a) roughening the surface of a stretched high molecular weight film; (b) applying to said roughened film an undercoat consisting essentially of an aqueous gelatin solution containing 5 to 15% by weight of gelatin and a gelatin hardener; (c) drying said undercoat by heat treatment at a temperature within the range Tg40 C. to T +40 C. wherein T is the glass transition temperature of said film; and (d) applying to said undercoated film a photographic emulsion or suspension containing gelatin as a binder.
2. The process of claim 1 wherein said film is roughened by first contacting said film with an organic solvent capable of swelling said film and then further contacting said film with a second solvent which is miscible with said organic solvent but will not dissolve said film.
3. The process of claim 1 wherein said film is comprised of a resin selected from the group consisting of polystyrene, polyester and polycarbonate.
4. The process of claim 3 wherein said film is comprised of polystyrene and said drying is efiected at a temperature of from 60 to C.
5. The process of claim 3 wherein said film is comprised of polycarbonate and said drying is effected at a temperature of C.
6. A process for the production of a photographic material which comprises the steps of (a) roughening the surface of a stretched high molecular weight film; (b) applying to said roughened film an undercoat consisting essentially of a dispersion of gelatin in an organic solvent containing from 0.5 to 5% gelatin by weight and a gelatin hardener; '(c) drying said undercoat by heat treatment at a temperature within the range T -40 C. to T +40 C. wherein Tg is the glass transition temperature of said film and (d) applying to said undercoated film a photographic emulsion or suspension containing gelatin as a binder.
7. The process of claim 6 wherein said film is roughened by first contacting said film with an organic solvent capable of swelling said film and then further contacting said film with a second solvent which is miscible with said organic solvent but will not dissolve said film.
8. The process of claim 6 wherein said film is comprised of a resin selected from the group consisting of polystyrene, polyester and polycarbonate.
References Cited UNITED STATES PATENTS Brandt 11734 Takenaka 117'34 Tani et a1. 11711 Houck et a1. 117-34 Nadeau et a1. 11734 Starck 117--34 117 7, 47 A, 138.8 R, 138.8 E, 138.8 UA, 96 7 1;