JPS5950967B2 - Method of manufacturing photographic materials - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method and apparatus for producing photographic materials.

In particular, it relates to a manufacturing method and apparatus in which a silver halide emulsion in the form of a gel is melted, mixed in a mixer with photochemical additives, and then cast onto a transport web of paper or film. The solidified photographic silver halide emulsion is usually melted in a heated container. To this end, the solidified base emulsion is transferred from the cooling chamber into a relatively small container and introduced in the form of lumps each weighing approximately 1 kg into the melting container. The heat required for melting must be applied to the emulsion externally through the walls of the container. In order to avoid unduly long heating times and therefore batch times, it is necessary that the temperature difference between the wall and the emulsion be fairly large. This can only be achieved if the temperature of the container walls is significantly higher than the required final temperature of the emulsion. During the melting process, the emulsion is kept in constant motion by a stirrer to increase heat transfer. Nevertheless, batch times of about 3 to 4 hours are common for containers in the 500 to 1000 liter capacity range. After melting, the base emulsion is mixed with a variety of photochemical additives; the additives may be used to improve, for example, the sensitivity required for a particular region of the spectrum, stability during casting, stability during storage, and Adding desirable fogging behavior, etc.
Modify the properties of the photographic material in some desirable respects.

These additives generally need to be added in a certain order and at certain intervals to obtain the desired effect. The samples are then tested for quality control of the photographic material. After passing the quality test, the melt is finally released for application. By this time, approximately 5 hours are required from the start of the process. The capacity of the above container is approximately 500~
Assuming 1000 liters, approximately 3 to 6 hours are required for coating at an emulsion flow rate of approximately 2.5 liters per minute. Therefore, for some portions of the emulsion, about 10 hours elapse from the time of melting to the time of casting. In contrast, the portion of the emulsion that is melted at the end of the process and cast first has a residence time of only about 2 hours. The most important disadvantages of batch operations can be summarized as follows.

The required high temperature of the vessel walls causes some portions of the emulsion to become overheated. This deteriorates the photographic properties of the emulsion. Furthermore, the photographic properties of individual batches cannot be easily reproduced. The portion of the emulsion outside the bulk emulsion will melt faster than the portion of the emulsion inside the bulk, depending on, for example, the batch time of the container. As a result, different parts of the emulsion are exposed to different morphological changes over time. This is highly detrimental, especially in the case of extremely sensitive color emulsions. An emulsion that is ready for casting retains its photographic properties for a limited period of time.

If the coater is not operated for a long time, the remaining emulsion becomes unusable resulting in significant losses. It has been found that, especially in the case of high-speed color emulsions, the so-called ripening time must be kept as short as possible, and also that the ripening time should be uniform for all parts of the emulsion in order to obtain a constant quality. .

Aging time is the time that elapses from the time the emulsion melts at a temperature of about 40°C to the time the emulsion is cast onto the layer substrate. It is an object of the present invention to provide a method and apparatus for continuously producing photographic emulsions ready for cast molding.

In the present invention, both the ripening time and the residence time of the emulsion in the individual steps are important factors. It has surprisingly been found that the quality of the photographic material is improved and especially the reproducibility of the quality is improved if the ripening time is kept as short as possible and over the entire part of the emulsion. Another important factor is that the entire facility should be able to be switched over in the event of a failure in the manufacturing process. For the same reason, the volume of equipment between the melting zone and the application device should be as small as possible.

The present invention uses a silver halide emulsion to produce a photographic material by adding and mixing a photochemical additive (photographic additive) to a silver halide emulsion and continuously applying the mixture to a transition web. is introduced into multiple mixing devices in a continuously operated mixing process, provided that it is sequentially mixed with the introduced additive in each mixing device and mixed with the introduced additive before introducing the next additive in the next mixing device. In a method for producing a photographic material by controlling the flow rate (volume) of silver halide emulsion and additives through the process based on the in-coater consumption of silver halide emulsion ready for coating, comprising: ) feeding said silver halide emulsion in the form of a gel to a melting step before mixing with said additives; (b) passing saturated steam through the pipes of a grid placed in said melting step; By heating the silver halide emulsion in gel form by the grid heated by the grid, only a part of the silver halide emulsion is melted in the melting step, and (c) continuous coating step. In order to maintain the flow rate of the melted emulsion from the melting process,
In order to maintain the amount in relation to the throughput (Throughput) of the mixing process, the amount of water vapor in the pipe is increased so that the silver halide emulsion in gel form is melted in an amount necessary to maintain the outflow amount. The present invention relates to a method for producing a photographic material characterized by automatically controlling the flow rate.

Referring to the apparatus for the continuous production of photographic materials which can be used for carrying out the method of the invention, it comprises melting means for melting the solid photographic emulsion, mixing means for mixing it with photochemical additives, and coating the transfer web. a coating machine for melting the solid emulsion, the melting means comprising a cylindrical container, a heated grid (G
(rid), controlling the heating power of the grid and thus controlling the rate of emulsion leaving an outlet at the bottom of the melting vessel such that the rate of emulsion leaving is equal to the throughput in the mixing means connected to the melting means; the mixing means consist of a tubular body with a population arranged continuously in the direction of flow, the inlet of which communicates with the supply container of the individual photochemical additive through a metering pump, and has a moving part; Each non-recirculating mixing zone is located between successive inlets; and the outlet of the mixing means is connected to a non-recirculating applicator.

In one embodiment of the invention, the bottom of the melting vessel and the heating grid for melting the emulsion are separated by another heating grid that serves as a tempering grid for tempering the emulsion. .

Both heating grids are filled with vacuum saturated steam as heating medium. The base of the melting vessel is preferably funnel-shaped and equipped with a level sensor to control the saturated steam flowing through the melting grid and thus the rate of heat transfer as a function of the liquid level at the bottom of the funnel. .

Cascade and vacuum applicators have proven particularly suitable as non-recirculating applicators. These applicators are described in more detail in the description of exemplary embodiments below. Preferably, the mixing means are connected to the coater through heated pipes to prevent the emulsion from cooling down.

The present invention provides many advantages over conventional methods.

They are: (l) Aging time can be considerably shortened.

Instead of a time range of 5 to 10 hours in a batch operation,
Aging time can be shorter than 1 hour. In this way, it is possible, especially in the case of light-sensitive color emulsions with high silver contents, to obtain significant improvements in quality due to the influence of smaller silver halide grain diameters. The long ripening times of batch operations promote the formation of relatively coarse grains because the silver halide grains agglomerate over time. Surprisingly, it is also possible to improve the quality reproducibility. This can be attributed to the fact that all emulsions have essentially the same residence time in the equipment from the moment they melt to the moment the molten emulsion is applied to the transport web. This is only possible by combining the individual device parts according to the invention. For example, when using a mixing means with a stirrer or a coater with recirculation equipment (for example a DOctOr type coater, in which excess emulsion is scraped off), the residence times of the individual parts of the emulsion are proportional. It will be different. (2) The temperature of the heating medium in the heating grid is only 2-3° C. higher than the required emulsion temperature.

This avoids damage to the emulsion due to overheating. The low temperature of the heating medium is made possible by the fact that each grain of the emulsion, once melted, is immediately flushed away from the heating surface. (3) It is possible to minimize the loss of photographic emulsion in the middle stage of the structure of the melting vessel and mixing means.

Emulsion losses during production interruptions are limited to losses in the mixing means, the pipe system to the coating machine, and the coating machine itself. However, this is an order of magnitude smaller than the losses associated with batch operations. Another advantage of the invention is that it takes only a short time to adjust the vacuum saturated steam heating, for example if it is necessary to change the temperature or to switch off the heating altogether.

In case of production interruption, the melting process can be stopped very quickly and
And the device can be operated again immediately after the fault is removed.
Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which: FIG. 1 2 schematically illustrates an overall apparatus for producing an emulsion ready for casting.

Figure 2 shows the melting means of the device. Figure 3 shows the mixing means by which photochemical additives are introduced.

Referring to FIG. 1, solid photographic silver halide emulsions are stored in a cooling chamber (not shown) and conveyed by a transport container 1 to a melting means 2 in which each of the emulsions is It is introduced in the form of a mass 3 weighing approximately 1 kg.

At the lower end of the melting means 2 there is a heating grid 5, which serves as a melting grid on which the emulsion mass 3 rests. The heating grid 5 is filled with vacuum saturated steam, which acts as a heating medium. When the heating switch is turned on, the emulsion mass melts and the liquid emulsion 6 collects in the outlet funnel 7 from which it flows into the mixing means 8 and the individual photochemical additives 91-95 are added. and mixed. Mixing takes place in a mixing zone 10 into which the additive 9 is introduced only after the previous additive has been thoroughly mixed with the emulsion. The figure also shows volumetric containers 11 for the individual components 91-95 and the base emulsion 6. The drawing also shows the metering pump 13
Also shown is a common drive for. The photographic emulsion ready for casting is transported from the outlet end of the mixing zone 10 through a heated pipe 14 to a container 15 located near a coater 16.

The emulsion from the container 15 is immediately transferred to the pipe 18 by the pump 17.
It is sucked up to the coating machine 16 through the. The level of emulsion in the container 15 is sensed by a sensor 19 and the sensing result is used in a line to control the drive 12, 12'' for the metering pump and thus the amount of emulsion flowing into the container 15. 19″. Applicator 16 is non-recirculating, ie, the rate of emulsion applied to web 20 is comparable to the rate of emulsion delivered by pump 17. In this case, the coater 16 is a single layer coater. However, it would be readily possible to use a multilayer coater.
In this case, the emulsion ready for casting would be produced with separate melting and mixing means for each layer. It would also be possible for the emulsion to be composed of several types of emulsions, and separate melting means would be required for each type of emulsion. In this case, an emulsion ready for casting would be produced with all melting means and common mixing means. Aspects of the construction and operation of the melting means will now be described in further detail with reference to FIG.

The melting means is an emulsion supply cylinder 21. It consists of a cylindrical diversion sleeve 22, a melting grid 5 (see also FIG. 1), a tempering grid 23 and an outlet funnel 7 at the bottom of the melting means. The outlet funnel 7 has a dip pipe 24 mounted therein for measuring and controlling the liquid level. Both the melting grid 5 and the refining grid 23 are heated with vacuum saturated steam. The two heating grids are in the form of coils or grids. For melting grids, the gap between two adjacent heating tubes is approximately 5 m.
m, whereas in the case of the refining grid 23 the corresponding gap is approximately 1 mm. The outlet funnel 7 and the diversion sleeve 22 are double walled, which double wall means a heating jacket which may be heated. The sleeve 22 and the heating jacket of the funnel 7 and the grids 5j and 23 are evacuated by water pumps 25 and 26. Emulsion outlet 27
A temperature sensor 28 attached to the vacuum saturated steam supply pipe controls a valve 29 in the vacuum saturated steam supply pipe.

The melting process is performed as follows.

The emulsion is under normal dog pressure during the entire melting process.

After the cylinder 21 has been filled with a mass of gel-type emulsion, the apparatus can be started with the degassing pumps 25 and 26 in operation. Conversion sleeve item 22
The pressure in the heating jacket of the outlet funnel 7 and in the melting grid 5 and tempering grid 23 is then reduced until reaching a level of, for example, 70 mmHg, corresponding to a saturated steam temperature of 44°C. At this pressure level steam valves 29 and 30 open automatically. The steam valve 30 is connected to the conversion sleeve 22
and a melting zone consisting of a melting grid 5;
On the other hand, the steam valve 29 serves the refining zone consisting of the refining grid 23 and the outlet funnel 7. Under these conditions, the melting zone initially runs at maximum power. The solid emulsion melts at the interface and flows through tempering grid 23 to outlet funnel 7. The steam valves 29 and 30 open and close until a predetermined level is reached in the outlet funnel 7 as measured by the dip pipe 24 and the pressure transmitter 24a connected thereto.
A pneumatic control circuit connected to the pressure transmitter controls the steam valve 30 and thus the output of the melting zone according to the liquid level in the outlet funnel 7. The reduced pressure, measured by another pressure transmitter (not shown), changes its value depending on the heating power prescribed by the level control circuit.
Once the reduced pressure exceeds a maximum level defined at, for example, 70 mm Hg, the steam valves 30 and 29 will operate until the reduced pressure falls below 70 mm Hg again, regardless of the particular valve position defined in the control circuit. close. This prevents the emulsion from being exposed to temperatures higher than 44°C. The temperature prevailing in the tempering zone is measured by an electrical resistance thermometer 28 in the outlet 27 and is kept constant at 40° C. through a steam valve 29 by means of a temperature control circuit.

The emulsion flows from the melting zone through a tempering grid 23 where it is heated or cooled to 40°C. Like the melting zone, the tempering zone is equipped with a limit monitoring device which closes the steam valve 29 if the temperature rises above 42° C. until the temperature falls again. The liquid emulsion can be moved through outlet 27 at any desired speed up to 61/min.

Emulsion transfer can be interrupted at any time without having to change out the entire device. When the flow of emulsion is interrupted, the level of emulsion in the outlet funnel 7 initially rises. As a result, the steam valve 30 is closed by the level control circuit. Degassing of the melting zone reduces the temperature prevailing in that zone to about 16° C. and the melting process is automatically stopped until emulsion transfer begins again. From outlet 27 the molten emulsion flows to mixing means 8 (see FIG. 1).

The flow path of the emulsion through the mixing means is shown in FIG. The base emulsion is fed to the device from a port 31, flows through a metering and control vessel 11a, and is then pumped by a mainstream metering pump 32 into a continuously arranged hairpin-shaped mixing zone 35. The additives 9, to 9, are subsequently introduced into the main stream via the inlet 34 by means of the metering piston pump 13. The main flow pump 32 and all metering pumps 13 are connected to a common drive 1
2,12'. Preferably, the phases of the pumps are adjusted so that the pumps transmit in sequence. The throughput in the mixing zone is varied by the rotational speed and is matched to the emulsion consumption by a control circuit (see FIG. 1) connected to the level sensor 19. Since the mixing ratio remains constant regardless of throughput, the composition of the emulsion also remains constant. The mixing ratio is additionally controlled at regular time intervals by measuring control vessels 11, 11a in the supply lines to metering pumps 13 and 32. With this method any erroneous doses can be detected immediately. Each mixing zone 35
consists of two tubes arranged one after the other in the shape of a hairpin.

Within each tube is a helix 3 having a diameter substantially equal to the inside diameter of the tube.
There are 6. The dimensions of the helix are its advance (Iead)
) and the inner diameter is approximately 2:1. In addition to the hairpin mixing zone 35, other static mixing has also proven suitable. The inlets 34 of the individual components 9, to 9, are tangential tubes.
s) or, in a preferred embodiment, is in the form of a water fountain.

The emulsion ready for casting is at outlet 3 of the mixing means.
7 and sent through a heated tube 14 (see FIG. 1) to a coating machine. The average residence time of the emulsion in any given portion within mixing zone 35 is governed by throughput.

During operation of the device, the residence time generally does not exceed 50 seconds. Additives 9, to 9, can include, for example, dyes for photosensitization, organic/chemical substances for stabilization, wetting agents, hardening agents, coloring components, optical softeners and width-control agents. . A very thorough mixing is obtained in the mixing zone 35 so that a thorough mixing with the main stream always takes place before a new additive is introduced.

The emulsion ready for casting supplied by the mixing means is quantitatively applied to a transport web of paper or film.
(Figure 1). The coating equipment used is a cascade coating machine.

Coating machines of this type consist of a coating plate extending over the entire width of the web with an inclined flow plane interrupted by a feed interval of photographic emulsion. The coating roller, through which the web 20 to be coated is guided, is arranged at a narrow distance from the coating plate. The coating liquid flows downward on the flow plane in the form of a thin layer,
In the case of a multilayer coater, the liquid then comes into contact with other similarly formed layers one after the other. The various layers form a multilayer band of liquid flowing at the lower end of the flow plane (where a so-called application meniscus is formed that wets the web over its entire width) and overlies the other layers without mixing. Pile up. This type of applicator is known, for example, from German Patent Specification No. 1151.
No. 173 and US Pat. Nos. 2,761,417 and 2,761,419. It is also possible to use so-called suction applicators instead of cascade applicators.

A suction type applicator is known, for example, from German Patent Specification No. 130376.
No. 3 and US Pat. No. 3,645,773. In a suction coater, the web is moistened in a closed coating chamber that is connected to an emulsion supply container, which is in communication with the suction coater. During operation of the coater, a hydrostatic vacuum is created along the emulsion feed line. The level of hydrostatic vacuum can be varied by vertical adjustment of the supply vessel or by creating a vacuum within the supply vessel. In this way, the thickness of the coated emulsion layer can be adjusted very accurately and reproducibly. Both cascade and vacuum applicators are non-recirculating, i.e. they do not require any compensator (
DOctOr) or equivalent components and do not return the removed photographic emulsion to the coater.

EXAMPLES The preparation and casting of color emulsions is described by the following examples.

The paper web to be coated (see Figure 1) is 137 cm.
The color emulsion is applied at a casting speed of 43 meters/min. The emulsion was coated at a rate of 57 g/d and had a density of 1.03 kg/day.

To produce this, the throughput in the melting means 2 and the mixing means 8 is 3.25 liters/min or 195 liters/hour. By means of the metering pumps 13, 32, the base emulsion coming from the melting means is made ready for casting in the mixing zone 35 according to the following recipe.

Additives 1-VI are color components, sensitizers, stabilizers, emollients, ratio modifiers, hardeners, and wetting agents.

The speeds quoted in the table relate solely to the mixing ratio and the consumption of emulsion per unit time to the casting data given in the examples. The consumption per unit time can deviate slightly from this average value both due to the influence of the fluctuations in the level in the container 15 and the influence of the resulting changes in the rotational speed of the drive 12, 12'' of the metering pump. The volumes of each part of the apparatus are as follows: Based on these data, the total residence time from melting of a portion of the emulsion to casting is approximately 30 minutes.

This contrasts well with batch operations, where residence or aging times are on the order of 5 to 10 hours. In the process according to the invention, therefore, the ripening time can be reduced by essentially an order of magnitude compared to the known process.

[Brief explanation of the drawing]

FIG. 1 illustrates the entire apparatus for producing an emulsion ready for casting. Figure 2 shows the melting means of the device. Figure 3 shows the mixing means for introducing the photochemical additives: 2...melting means, 3...massive emulsion, 5...heating grid, 6... ...Liquid emulsion, 8...Mixing means, 9...Photochemical additive, 10...
・Mixing zone, 13... Metering pump, 16...
... Coating machine, 20 ... Web, 23 ...
・Adjustment daritsudo.

Claims (1)

[Claims] 1. A silver halide emulsion is mixed with photochemical additives and mixed in a continuous operating mixing process to produce a photographic material by sequentially applying the silver halide emulsion to a transitional web. However, before introducing the next additive in the next mixing device, the silver halide emulsion and additives are sequentially mixed with the introduced additive in each mixing device and passed through the mixing process. A method for producing a photographic material by controlling the flow rate (volume) of a silver halide emulsion on the basis of the in-coater consumption of a silver halide emulsion ready for coating, comprising: (a) mixing with an additive as described above; supplying said silver halide emulsion in the form of a gel to a melting step, (b) with said grid heated by passing saturated steam through the pipes of the grid placed in the melting step; By heating the silver halide emulsion in gel form, only a portion of the silver halide emulsion is melted in the melting step; (c) for the purpose of maintaining a continuous coating step, the melted emulsion from the melting step; In order to maintain the outflow amount at an amount corresponding to the throughput of the mixing step, the gel-form silver halide emulsion is melted in the pipe in an amount necessary to maintain the outflow amount. A method for producing a photographic material, characterized in that the flow rate of water vapor within the material is automatically controlled.