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Publication numberUS2912343 A
Publication typeGrant
Publication dateNov 10, 1959
Filing dateNov 10, 1958
Priority dateNov 18, 1957
Publication numberUS 2912343 A, US 2912343A, US-A-2912343, US2912343 A, US2912343A
InventorsBernard Collins Ronald, William Welford Stanley Freder
Original AssigneeIlford Ltd
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Production of photographic material
US 2912343 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

Nov. 10, 1959 R. B. COLLlNS ETAL PRODUCTION OF PHOTOGRAPHIC MATERIAL Filed Nov. 10, 1958 United-States I Patent ice PRODUCTION or PHOTOGRAPHIC MATERIAL Ronald Bernard Collins and Stanley Frederick William Welford, Ilford, England, assignors to Ilford Limited, Ilford, England, a British company Application November-10, 1958, Serial No. 772,956

Claims priority, application Great Britain November 18, 1957 2 Claims. (Cl. 117- 34 This invention relates to the production of colour photographic materials. I

In one main method of colour photography there is provided a photographic element which comprises a support carrying three silver halide photographic emulsion layers which are differentially sensitive to three regions of the visible spectrum, normally blue, green and red, and which contain compounds, so-called colour couplers, which will combine with the oxidation products of aromatic primary amino developing agents used to develop silver images in the layers to form dye images which are complementary to the utilised sensitivity of the respective layers.

Thus, for example, the photographic element may comprise the following layers in super position:

(a) Colourless film support.

(b) Silver halide emulsion layer sensitised to red light by means of an appropriate sensitising dye and containing a colour coupler yielding a cyan image.

(c) Silver halide emulsion layer sensitised to green light by means of an appropriate sensitising dye and containing a colour coupler yielding a magenta image.

(d) A yellow filter layer the colour of which may be readily destroyed.

(e) Silver halide emulsion layer having its natural sensitivity to blue light and containing a colour coupler yielding a yellow image.

The assembly may contain other layers, e.g. outer layers, masking layers, substratum and supercoat layers, according to the specific requirements in the product. The specified yellow filter layer (d) acts as a barrier to blue light reaching layers (b) and (c). I,

When such a layer is processed by exposure, development in an ordinary black and white developer, reexposed, re-developed in a developer which is an aromatic primary amine such as N.N- diethyl-p-phenylene diamine, or its closely analogous compounds, and the silver removed from the product, there is obtained a film product which has positive images in cyan, magenta and yellow in layers (b), (c) and'(e)' respectively, and which thus presents by transmitted light a more or'less true colour record of the subject to which the film was exposed.

Such colour photographic material is of relatively slow speed, and though several factors contribute to this, one

important factor is that there is a tendency for the colour 7 couplers which are added to the emulsion layers to reduce very considerably the photographic speed of the layers. This is particularly so in the case of the redsensitised layer where the colour couplers yielding cyan dyes which are commonly used are phenolic compounds or naphtholic compounds. It appears probable that the colour coupler tends to displace the red-sensitising dye from the silver halide grains and thus, by reducing the effect of the dye, reduces the speed of the emulsion to red light very considerably. Attempts have been made to overcome this difficulty by a careful selection of red-sensitising dye (compare, for example, British Patent No.

' 2 625,992), but there are limits to this possibility and in fact no red-sesitising dye of adequate sensitising effect has yet been found which will be wholly unaffected by the addition to the emulsion of a phenolic type colour coupler.

It has now been found, however, that the reduction in speed of the emulsion consequent on the addition of the colour coupler takes place primarily While the emulsion is in liquid bulk form and will occur very much more slowly, if at all, after the emulsion has been coated and set-as, a layer onthe support. Thus the emulsion, containing the colour coupler, deteriorates in speed with time so that, as it is coated, the speed of the coating obtained decreases with consequent change in colour balance.

According to the present invention, therefore, in the method of producing colour photographic materials whichcom'prises applying to a support layer a silver halide photographic emulsion which contains a coloursensitising dye and .a colour coupler, or other compound the presence of which tends to reduce the sensitivity of the emulsion, the emulsion containing the colour-sensitising dye and a solution of the colour coupler or said other compound are intimatelyadmixed in the required proportion at or near the siteof the coating device and the mixture is coated with the minimum possible time delay between the time of mixing and the time when the emulsion is coated, and the coated emulsion is set and dried with the minimum of delay.

Various mechanical mixing devices known per se may be employed to produce the final emulsion for coating. Thus theemulsion and additive solution may be pumped as separate streams to a mixing cylinder and pass, via baflies, directly to the coating head of the coating machine.

Any of the well known methods of coating photographic emulsions may be employed, but generally one difference in working must be employed. In some methods part of the emulsion passing the coating head runs back to the coating head, i.e. the excess over the requirement (set by the thickness of the layer to be coated) is returned to the main bulk of emulsion. These methods cannot generally be employed in accordance with the presrent invention since it means that part of the emulsion leaving the coating head, and which is still deteriorating in speed owing to the effect of the additive, becomes mixed in with the fresh emulsion thus reducing its overall speed. Accordingly, such methods must generally be adopted with the variation that any run-back of'emulsion is diverted and discarded. However, if the percentage run-back is not too excessive and the coating speed is fairly high, it is possible to set up equilibrium conditions in which, although there is some run-back, the photographic speed of the emulsion actually coated onthe support is not unduly reduced.

Preferably those methods of coating will be employed in which there is no run-back of emulsion to the coating head, i.e. methods in which the quantity of emulsion passed by the coating head is strictly metered to that required to give the desired coating thickness. Moreover, it is important that at all times the quantity of prepared emulsion waiting to be coated shouldbe the min imum possible. For this reason so-called slab-coating is preferred. The method normally provides a small surplus of emulsion which is recirculated and it may therefore be provided that any increase in the overflow rate is electronically detected and the information fed back to control the coating speed. In this way it is arranged that any increase in overflow automatically increases coating speed and therefore the rate of pick-up of the emulsion, so that the overflow is immediately compensated.

Alternatively, various methods whereby the prepared Patented Nov. 10, 1959 emulsion is extruded on to the support may be employed.

It has been found that, by employing the method of this invention for the coating of the red-sensitive layer in the production of a colour film which, as normally prepared, has a Weston speed of about 10, it is possible to obtain film of identical colour characteristics but a Weston speed of 60 to 80.

The following example will serve to illustrate the invention:

Example A silver halide emulsion containing 188 gms. of silver and 350 gms. of gelatin is spectrally sensitised to the red end of the spectrum during its manufacture by the addition of 600 mls. of a 1:2000 solution of 3:3'-dimethyl 6:6 dimethoxy 9[1:5 dimethyl 2 phenyl- 3-oxo pyrazolinyl (4)] thiacarbocyanine bromide: 260 gms. of gelatin and 100 mls. of wetting agent are added and after adjustment of the pH to 7.4 the total bulk is made up to 11,000 gms. The colour former solution, which is the additive described in this example, contains 310 gms. of gelatin and 170 gms. of colour former (to form a cyan image) added as a 5% solution of the sodium salt of l-hydroxy-2-naphthoyl-stearylaminel--sulphonic acid. After adjustment of its pH to 7.4 the solution is diluted to a total bulk of 11,000 gms. The two solutions thus compounded have approximately equal viscosities measured as cps. at the temperature of coating, 355 C.: this equality of viscosity assists mixing: owing to the interaction of the colour former with the gelatin of the emulsion the viscosity of the mixed solutions rises to 18 cps.

The emulsion and colour former solutions are held in vessels thermostatically controlled at the coating temperature and each is fed into similar metering pumps driven at the same speed from a motor driven variable speed gear box so that although the ratio of the mixing of the two fluids is invariable yet the total flow can be adjusted to meet the requirements of coating. The metering pumps are of conventional design. The two metered flows are then fed into the mixing cylinder.

A suitable mixing chamber is illustrated in the accompanying drawing. It consists of a small squat form cylinder 1 mounted vertically: a thick rotating spindle 2 runs centrally down the cylinder having its lower bearing on the base and its upper bearing on a bafiie 11 across the cylinder. Attached to the spindle at its lower end is a small plastic covered magnet 3 which serves a dual purpose; primarily it is the drive, this being achieved magnetically from outside by means of the rotating magnet 4 driven from the gear box 5 and the motor 6. Secondarily it serves as the first stage of mixing as the two liquids are fed into this section of the cylinder from opposite entry ports 7 and 8. This method of driving obviates the need for glands thus reducing the chances of contamination or the introduction of air bubbles. The upper portion of the cylinder 1 is divided by baflies 9 into segments, the liquid flow between the segments being at the periphery of the battles Mounted on the spindle and running closely between the baffles 9 are discs 10, the mixing being brought about by the rotation of the discs 10, the upward flow of liquid taking place at the outer edges of the bafiles 9 where it is sheared by the rotating discs 10. These may operate at 100 rpm. The mixed liquid then flows through holes in the baffie supporting the upper bearing, through the exit port 12 at the top of the cylinder 1, and then direct to the coating head where it is continuously coated on film base at a coating speed of 10 feet per minute. The coated film passes, a few seconds after being coated, through a chill-box which sets the emulsion, and then through a drying chamber.

On examining a 500 foot length of the coating by sensitometric exposures through a filter passing only the longer wavelengths of the spectrum, no changes in speed were found, the whole coating being quite uniform.

In other experiments not employing the method described above but working with the same final emulsion, a gradual loss of red-sensitivity was found amounting to log E 0.30 over the period of time that would be taken in coating a 500 foot length (50 minutes).

Whilst the invention has been described with particular reference to the case where the additive is a colour coupler, it will be understood that it is applicable to any case where the additive is one which tends to reduce the sensitivity of the liquid emulsion over a period of time. Thus it also includes the case where the additive is a dyestuff, e.g. an azo dyestuif, which has such an effect.

What we claim is:

1. In a method of producing colour photographic materials which comprises: preparing a color sensitized silver halide emulsion by adding a color sensitizing dye to a silver halide emulsion; thereafter adding to the sensitized emulsion a color coupler the presence of which tends to reduce the sensitivity of the emulsion, and thereafter applying the resulting composition to a support layer as a coating thereon; the improvement which comprises: deferring the addition of the color coupler solution to the color sensitized emulsion until the color sensitized emulsion has been brought to the site at which it is to be applied to the support layer and thereupon admixing the color coupler with the color sensitized emulsion; and promptly thereafter applying the freshly formed admixture to the support layer whereby the support is coated with the minimum possible time delay between the time of admixing and the time of coating, and the coating is set and dried with the minimum delay.

2. In a method of producing colour photographic materials which comprises: preparing a color sensitized silver halide emulsion by adding a color sensitizing dye to a silver halide emulsion; thereafter continuously adding to the sensitized emulsion a color coupler the presence of which tends to reduce the sensitivity of the emulsion, and thereafter continuously applying the resulting composition to a support layer as a coating thereon; the improvement which comprises: deferring the continuous addition of the color coupler solution to the color sensitized emulsion until the color sensitized emulsion has been brought to the site at which it is to be applied to the support layer and thereupon continuously admixing the color coupler with the color sensitized emulsion; and promptly thereafter continuously applying the freshly formed admixture to the support layer whereby the support is coated with the minimum possible time delay between the time of admixing and the time of coating, and the coating is set and dried with the minimum delay.

References Cited in the file of this patent UNITED STATES PATENTS 2,280,300 Potter et a1. Apr. 21, 1942 2,295,276 Wilmanns et al. Sept. 8, 1942 2,415,644 Leonhard et al. Feb. 11, 1947

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2280300 *Jan 14, 1941Apr 21, 1942Defender Photo Supply Co IncLight sensitive photographic coating and method of manufacturing the same
US2295276 *Jun 21, 1939Sep 8, 1942Gen Aniline & Film CorpPhotographic emulsion
US2415644 *Nov 16, 1942Feb 11, 1947Eastman Kodak CoMethod and apparatus for continuously applying a coating to a web and controlling the thickness of the same
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3116913 *May 29, 1961Jan 7, 1964Kingdon LaneLiquid agitating apparatus
US3212887 *Apr 7, 1961Oct 19, 1965Minnesota Mining & MfgLaterally disposed coterminously adjacent multicolor area containing graphic reproduction receptor and electrophotographic process of using same
US3632373 *Apr 1, 1968Jan 4, 1972Eastman Kodak CoMethod for preparing silver halide layers having substantially uniform image contrast
US3996140 *Feb 7, 1975Dec 7, 1976Ab TellusondApparatus for continuous liquid-liquid extraction of water with a solvent
US4132511 *Oct 11, 1977Jan 2, 1979Varian Associates, Inc.Damper for high pressure pumping system
US4134769 *Aug 5, 1977Jan 16, 1979Mitsubishi Paper Mills, Ltd.Betaine and anionic type cyanine dyes
US4416548 *Feb 17, 1981Nov 22, 1983Sunds Defibrator AktiebolagApparatus for gas or liquid admixture
US4496245 *Mar 7, 1983Jan 29, 1985International Business Machines CorporationLiquid chromatography proportioning valve and mixer
US4832991 *May 2, 1988May 23, 1989Eastman Kodak CompanyCoating process
US5061079 *Mar 12, 1990Oct 29, 1991Satake Chemical Equipment Mfg., Ltd.Stirrer
US5141327 *Jul 26, 1991Aug 25, 1992Satake Chemical Equipment Mfg., Ltd.Stirrer
US5202218 *Mar 19, 1991Apr 13, 1993Mitsubishi Paper Mills LimitedScanning exposing type lithographic printing plate with 1.5 wt. % of water or less
US5445913 *Feb 25, 1994Aug 29, 1995Eastman Kodak CompanyMixing spectrally dye-sensitized silver halide emulsion melt and dry diffusion transfer facilitating thermal solvent; coating substrate
US5985535 *Dec 23, 1997Nov 16, 1999Fuji Photo Film Co., Ltd.Mixing silver salt with halide, stirring, discharging and forming silver halide
US6022681 *Apr 16, 1998Feb 8, 2000Fuji Photo Film Co., Ltd.Forming fine grain nuclei in a dispersion medium solution, ripening to preferentially eliminate nuclei other than tabular type, then growing into grains; for grains with large aspect ratio
US6109780 *Jan 22, 1998Aug 29, 2000S. P. Industries Inc.Dynamic vortex impeller
US8282267 *Apr 24, 2007Oct 9, 2012Artelis S.A.Mixing system including a flexible bag, specific flexible bag and locating system for the mixing system
US20090219780 *Apr 24, 2007Sep 3, 2009Jose CastilloMixing System Including a Flexible Bag, Specific Flexible Bag and Locating System for the Mixing System
EP0124795A2Apr 11, 1984Nov 14, 1984Fuji Photo Film Co., Ltd.Silver halide photographic emulsion
Classifications
U.S. Classification430/550, 366/303, 430/570, 366/273
International ClassificationG03C7/388, G03C1/10, G03C1/74
Cooperative ClassificationG03C7/388, G03C1/102, G03C1/74
European ClassificationG03C1/10B, G03C7/388, G03C1/74