JPH11262601A - Method for preparing and defoaming coating liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable coating application at a high speed while suppressing the foaming during the coating application of a coating liquid of a high viscosity and large flow rate by dissolving plural coating constitution liquids, then mixing these liquids to prepare a coating liquid and deaerating the liquid and subsequently subjecting the liquid to primary defoaming and secondary defoaming. SOLUTION: The plural constitution liquids constituting the coating liquid, for example, emulsion liquid, gelatin liquid, coupler, etc., are respectively stirred and dissolved in a prescribed amt. each by a stirring machine 11 in respective dissolving kettles 10 and thereafter, the mixture is fed into a mixing kettle 20 and while the mixture is dearated by the effect of a pressure reducing device 22, the mixture is stirred and mixed. Next, the liquid mixture is fed into, for example, a centrifugal separator 30 as the primary defoaming process by a pump 32, by which large-diameter foam is removed. After the liquid is once stored into a primary storage buffer 34, the liquid mixture is fed under pressurization to an ultrasonic defoaming device 40 as the secondary defoaming by a pump 43. The pressurized liquid is irradiated with ultrasonic waves, by which the small-diameter bubbles are dissolved. The annihilation of the foam is checked by a foam detector 50 through a pressure gauge 43, a pressurizing valve 44 and a flow meter 45 and thereafter, the liquid is sent to a coating applicator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preparing and defoaming a coating solution used for producing a photographic light-sensitive material, a heat-sensitive paper, a magnetic material and the like by coating the film on a support.

[0002]

2. Description of the Related Art As a conventional defoaming method for removing bubbles in a coating solution, there has been a method of first irradiating an ultrasonic wave, particularly a method of irradiating a pressurized coating solution with an ultrasonic wave. It has two defoaming effects, a bubble trapping effect and a bubble dissolving effect. Of these, the bubble dissolving effect has been used for photographic light-sensitive materials because it exhibits the effect of completely defoaming even small bubbles. On the other hand, this method has a limitation in processing capacity, and Japanese Patent Application Laid-Open No.
cp at a flow rate of 9 liters / minute, viscosity of 90 cp at a flow rate of 3 liters / minute, and JP-A-8-318102 discloses a flow rate of 5 liters / minute.
Examples of liters / minute, JP-A-3-157103, and a viscosity of 80 cp are described. A typical capacity limit point is a viscosity of 100 cp and a flow rate of about 3 liter / minute. Further, this method has a feature that the ultrasonic wave itself is weakened particularly when a large amount of bubbles are brought in.

[0003] Second, there is a method in which centrifugal force is applied to a coating solution to expel bubbles, or a method in which foam is expelled upward while casting a coating solution in a thin film form. Such a method is actually fair 3
-8322 No. 10-50p, Japanese Patent Publication No. 60-3847
No. 10000p, 98.5% removal at 10 liters / minute, JP-A-58-101708 discloses 15,000p, 10
Examples such as 85% removal at liter / minute are described.
It is used for high viscosity liquid of 0-15000p and the processing speed is 10
Generally, complete degassing is not performed at about 1 liter / minute. This system group has a constant capacity regardless of the foam size. In other words, the capacity is limited by the size of bubbles that can be separated, and there is a disadvantage that separation of small bubbles is disadvantageous in principle, and theoretically infinitely small bubbles cannot be separated.

[0004] In addition, there is a foaming phenomenon in which dissolved air in a coating solution is formed as bubbles during coating. As a method for suppressing this, deaeration by decompression or dissolved air desaturation by a drop in liquid temperature before coating is performed. It is known to do.

[0005]

In the application to a support, especially in the production of a photosensitive material, even a minute bubble in the application liquid may cause a failure and the coating liquid must be completely defoamed. No.

On the other hand, coating solutions tend to be concentrated and have high viscosity from the viewpoint of productivity, so that high-speed coating at a large flow rate tends to be performed, which is an increasingly severe condition for defoaming.

In the conventional method, there is a reduction in processing time and a reduction in processing effect due to an increase in the viscosity and flow rate of the coating liquid. That is, the load becomes too large to be able to remove bubbles, or a huge apparatus is prepared. Not preferred.

[0008] In particular, the lack of defoaming ability is caused by a coating method capable of high-viscosity, large-flow, high-speed coating such as a curtain coating method.
The original application ability is limited from the application liquid supply ability, and the industrial effect to improve is large. Furthermore, in the curtain coating method, since a curtain film is formed, which is a downstream film of the coating solution that has been thinly stretched, the inflow or mixing of bubbles into the curtain film causes a major trouble that the curtain film is destroyed. May cause, high demand for defoaming.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, is capable of coping with high-viscosity, large-flow, high-speed coating, is capable of defoaming, and dissolves, adjusts and mixes a coating solution while suppressing foaming during coating. It is an object of the present invention to establish a coating solution adjusting and defoaming method which enables the above.

[0010]

The object of the present invention is to achieve the object of "(1)
A dissolving process for dissolving a plurality of coating liquid constituent liquids, followed by a mixing process for mixing and adjusting them into a coating liquid, a degassing process for the liquid, and a primary defoaming for separating and removing large-diameter bubbles of the mixed liquid. A coating liquid adjustment defoaming method having a process and a secondary defoaming process of irradiating ultrasonic waves to a pressurized liquid obtained by pressurizing the liquid after the primary defoaming to dissolve small-diameter bubbles, wherein the secondary defoaming is performed. A process is downstream from the mixing process onward, wherein the primary degassing process and the degassing process are either between the dissolving process and the mixing process or during the mixing process or between the mixing process and the secondary defoaming process. Wherein the primary defoaming process and the degassing process each include one or more processes. "
Is achieved by However, the primary deaeration process and the deaeration process may be performed simultaneously.

Further, "(2) a dissolving process for dissolving a plurality of coating liquid constituent solutions, a mixing process for mixing them to prepare a coating liquid, a degassing process for the liquid, A primary defoaming process that separates and removes diameter bubbles,
A coating liquid adjustment defoaming method having a secondary defoaming process of irradiating ultrasonic waves to a pressurized liquid obtained by pressurizing the liquid after the primary defoaming and dissolving the small-diameter bubbles, wherein after dissolving the constituent liquid, a thin film The coating solution, wherein the coating solution is passed through the casting depressurization device individually or simultaneously to perform the degassing process and the primary defoaming process, and then perform the secondary defoaming process through the mixing process. Adjust defoaming method.

Alternatively, (3) a dissolving process of dissolving a plurality of coating liquid constituent liquids, a mixing process of mixing them to prepare a coating liquid, a degassing process of the liquid, and a large diameter of the mixed liquid A coating liquid preparation and defoaming method that has a primary defoaming process to separate and remove bubbles and a secondary defoaming process to irradiate ultrasonic waves to the pressurized liquid pressurizing the liquid after the primary defoaming to dissolve small-diameter bubbles A, through the dissolution process of the constituent liquid,
After having been subjected to the deaeration process and the mixing process by being added to a mixing vessel under reduced pressure, the secondary deaeration is performed through the primary deaeration process including a centrifugal separator or a thin film casting and decompression treatment device. A coating solution adjustment defoaming method characterized by performing a process.

[0013] Alternatively, (4) a dissolving process for dissolving a plurality of coating liquid constituent liquids, a mixing process for mixing them to prepare a coating liquid, a degassing process for the liquid, and a large diameter of the mixed liquid. A coating liquid preparation and defoaming method that has a primary defoaming process to separate and remove bubbles and a secondary defoaming process to irradiate ultrasonic waves to the pressurized liquid pressurizing the liquid after the primary defoaming to dissolve small-diameter bubbles Then, the deaeration process and the primary defoaming process are continuously performed in the thin film casting decompression treatment device through the dissolving process and the mixing process, and then the secondary defoaming process is performed. Characteristic coating solution defoaming method. Is a particularly effective method.
"(5) The liquid temperature is lowered between the secondary defoaming process and the coater (1).
(4) The method for preparing and defoaming a coating solution according to any one of (4) to (4). ", A more stable defoaming effect is obtained.

Further, "(6) The method for adjusting and defoaming a coating solution according to any one of the above (1) to (5), wherein the coating solution is a coating solution for a photographic light-sensitive material. And (3) the coating liquid is applied by a curtain coating coater (1).
The method for adjusting and defoaming a coating liquid according to any one of items (1) to (6). Is very effective.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors first studied the mechanism of disappearance of bubbles and obtained the following findings. That is, defoaming in the present specification, in a narrow sense, refers to separating and removing or dissolving bubbles in a liquid, and in a broad sense, gas such as air once dissolved in a liquid in addition to the narrow one, It also includes an operation of preventing a phenomenon that appears as bubbles again in the use stage. Degassing in a narrow sense is achieved by removing one of the aforementioned bubbles or dissolving and eliminating the bubbles. In any of the processes, an increase in the liquid viscosity or an increase in the liquid flow velocity increases the force for flowing out bubbles, the supplementary power is insufficient, and the processing time is reduced, so that the load simply increases.

As described above, there are two types of processes for defoaming. However, even if either one is selected, two processes are performed at the same time, or the separation and removal process is performed after the dissolution and disappearance process, it is only a combination. A large defoaming effect cannot be obtained. It has been found that the process is extremely effective only when only large bubbles are separated and removed, and then only small bubbles that cannot be removed are dissolved and eliminated.

The above-mentioned effects cannot be obtained by the conventional method in which two processes are simultaneously performed in parallel. This is because it is important that there is no large bubble that cannot be eliminated in the foam dissolving and disappearing process. In particular, in the dissolving and disappearing process of the foam, a method of applying liquid pressure in addition to ultrasonic irradiation is adopted. In this case, it was newly discovered that the bubbles were burst and crushed with only the small bubbles, and that the defoaming with high efficiency was performed. Secondly, it was found that the amount of bubbles brought in was large, and particularly when the bubbles remained large, the strength of the ultrasonic wave itself was greatly attenuated. In other words, when the ultrasonic liquid pressurization method is used in the process of dissolving and disappearing bubbles, there is a very remarkable difference between the small bubbles and the large bubbles, and the former has a remarkable large capacity. I found it to work. In addition, when the liquid pressure is applied in addition to the ultrasonic irradiation, as shown in the graph of FIG. 1, the range of the size of the small bubble effective for the bubble disappearance is expanded, and the bubble disappearance effect becomes more effective.

On the other hand, in order to stably maintain the defoamed state until the time when the liquid to be defoamed is used, it is preferable to add a deaeration process in addition to the above. In order to efficiently and strongly deaerate and obtain even higher stability,
Large bubbles were separated and removed, and only the small bubbles left behind were dissolved and annihilated by an ultrasonic pressure method, and it was concluded that a series of degassing processes with an additional degassing process was essential. . The above is the invention of the first group of the present invention.

In the case where the above is satisfied and the coating is performed while adjusting the solution continuously for a long time like a photographic light-sensitive material,
Two processes, a dissolving process and a mixing process, are separately required in preparation, irrespective of defoaming.

At this point, it is necessary to process a total of five processes in addition to the three processes relating to the defoaming described above. It becomes a production method that is difficult to operate at cost. Here, in addition to the above-described first group invention, a result of studying an effective combination in consideration of a minimum rule for obtaining an intended effect and an apparatus characteristic of each process is added as a second group invention, Effective configurations and rules for implementing at least the above five processes are provided as seven means as described in the preceding section.

More specifically, the configuration is as shown in FIGS. First, the configuration shown in FIG. 2 will be described. For example, a plurality of constituent liquids constituting the coating liquid to be coated, for example, an emulsion liquid, a gelatin liquid, a coupler, and the like, are stirred and dissolved by a predetermined amount in each dissolving vessel 10 by a stirrer 11 to complete the dissolving process. The mixture is stirred by the stirrer 23 while being degassed in the tank 21 connected to the decompression device 22, and the mixing process is completed. The mixture is sent to the centrifugal separator 30 as a primary defoaming process by the pump 32 to remove large-diameter bubbles. And stored in a temporary storage buffer 34 and pressure-fed by a pump 42 to enter an ultrasonic defoaming device 40 as a secondary defoaming process, irradiated with ultrasonic waves, and detected through a pressure gauge 43, a pressure valve 44 and a flow meter 45 to detect bubbles. After the disappearance of the foam is confirmed by the vessel 50, the foam is sent to the coater of the coating apparatus.

Here, the secondary defoaming process is after the mixing process. The primary deaeration process and the deaeration process are between the mixing process and the secondary deaeration process, but this may be performed during the mixing process, and the dissolving vessel 10 is provided as shown in the schematic configuration diagram of FIG. It may be located between the melting process and the mixing process having the mixing tank 20. As described above, the primary defoaming process and the deaeration process eliminate a large-diameter foam containing one or more bubbles and a foaming element in a subsequent step (coating step).

FIG. 3 schematically shows the structure as described above, but furthermore, degassing and primary defoaming located between the dissolving process having the dissolving pot 10 and the mixing process having the mixing pot 20. The process 35 uses a thin film casting depressurization method, and both degassing and degassing are efficiently performed. However, the present invention is not limited thereto, and a centrifugal degassing type may be used.

The components shown in the schematic constitutional diagram of FIG. 4 are prepared by dissolving each constituent liquid in a dissolving vessel 10 and then degassing while adding the mixture to a mixing vessel 20 under reduced pressure to perform a mixing process. Thereafter, the liquid is sent to the thin film casting and depressurizing device 30B, the primary defoaming process is performed, and the liquid is sent to the ultrasonic defoaming device 40 by the pump 42 via the storage buffer 34, and the secondary defoaming process is performed.

As the defoaming device for the primary treatment, a centrifugal separator can be used in place of the thin film casting and depressurizing device 30B, and the same effect can be confirmed. The deaeration by the decompression device in the mixing vessel 20 is useful for reducing the generation of bubbles as a pre-stage of the primary defoaming treatment and contributes to eliminating foaming in the coating process.

In the apparatus shown in the schematic constitutional view of FIG. 5, each constituent liquid is dissolved in a dissolving vessel 10 and then sent to a mixing vessel 20 to perform a mixing process under reduced pressure. After that, the thin film casting decompression device 30B
, Where the degassing process and the primary defoaming process are performed, and further, the liquid is sent to the ultrasonic defoaming device 40 by the pump 42 via the storage buffer 34 to perform the secondary defoaming process. .

Further, the effect of suppressing foaming during coating is as follows. In addition to the above-described degassing process, the liquid temperature is reduced while the secondary defoaming process is completed and the liquid is sent to the coater of the coating machine. The process can be further enhanced by providing a process.

This coating solution adjusting and defoaming method has a great effect in the production of a photographic light-sensitive material, especially in the production of a photographic light-sensitive material in which a high-viscosity, high-concentration, large-flow-rate coating liquid is applied at a high speed using a curtain coater coating apparatus. I understood that.

The defoaming ability was found to be 10 times higher in viscosity and 17 times higher in flow rate than in the past.

Test results as an example of the embodiment will be described below as a first embodiment.

Example 1 Defoaming solution: Photosensitive emulsion coating solution (addition and mixing of 3 solutions and thickener) Here, 3 solutions are an IIR-completed emulsion, a coupler dispersion and an aqueous gelatin solution. Used thickening polysaccharides. The surface tension of the liquid after mixing was 30 dyne / cm ² , the viscosity was measured with a B-type viscometer, and the gelatin concentration was 1
0%.

Foam detection: Performed with a foam detector.

Defoaming apparatus: 1) Conventional method Four liquids are dissolved and mixed, and deaeration under reduced pressure is performed by a batch method for 30 minutes. Further, an ultrasonic defoaming apparatus (25 kHz, 2 kW, capacity 5)
Degassing is performed with a pressure of 3 kg / cm ² liter.

2) Method 14 of the present invention Dissolve and mix the four liquids, perform degassing under reduced pressure in a batch system for 30 minutes, and further centrifuge (800 rpm, capacity 7 liters).
Primary defoaming with an ultrasonic defoaming device (25 kHz, 2 k
W, volume 1.5 liter, liquid pressurization 3 kg / cm ² ) to perform secondary defoaming.

3) Method 24 of the present invention After dissolving the four liquids, the primary defoaming and deaeration of the three liquids are performed by a reduced pressure thin film defoaming machine (capacity: 20 liters), the additives are mixed in the liquid, and the ultrasonic wave is further added. Secondary defoaming is performed by a defoaming device (25 kHz, 2 kW, capacity 1.5 liter, liquid pressure 3 kg / cm ² ).

Table 1 shows the results of testing the defoaming effect by changing the viscosity and flow rate of the liquid to be defoamed by each of the above defoaming devices. Here, the mark ○ indicates that good and complete defoaming is achieved, and the mark x indicates that complete defoaming is not possible.

[0037]

[Table 1]

As described above, the conventional defoaming method has a low viscosity,
When the flow rate is low, good defoaming is shown, but when both the viscosity and the flow rate increase, complete defoaming becomes impossible.On the other hand, when defoaming is performed by the method of the present invention, a considerably high viscosity, It was confirmed that complete defoaming was possible even for a high-flow rate defoaming liquid.

[0039]

According to the coating solution adjusting and defoaming method of the present invention, the deaeration of dissolved air in the coating solution is completely achieved together with defoaming.
A coating liquid supply method for applying a coating liquid with a high viscosity, a high concentration and a large flow rate at a high speed has been established.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a burst bubble diameter and a liquid pressure by ultrasonic irradiation.

FIG. 2 is a schematic configuration diagram of an example of a specific embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of an example of a specific embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of an example of a specific embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of an example of a specific embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Dissolution pot 20 Mixing pot 22 Decompression device 23 Stirrer 30 Centrifuge 30B Thin film casting decompression device 32, 42 Pump 34 Storage buffer 40 Ultrasonic defoaming device 43 Pressure gauge 44 Pressure valve 45 Flow meter 50 Foam detector

Claims (7)

[Claims] 1. A dissolving process for dissolving a plurality of coating liquid constituent solutions, a mixing process for mixing them to prepare a coating liquid, a degassing process for the liquid, and separating a large-diameter bubble of the mixed liquid. A coating liquid adjustment defoaming method having a primary defoaming process for removing and a secondary defoaming process for irradiating ultrasonic waves to a pressurized liquid obtained by pressurizing the liquid after the primary defoaming to dissolve small-diameter bubbles,
The secondary defoaming process is downstream from the mixing process and the primary defoaming process and the degassing process are performed between the dissolving process and the mixing process or during the mixing process or the mixing process and the secondary defoaming. The method of any of claims 1 to 3, wherein the primary degassing process and the degassing process each include one or more processes. 2. A dissolving process for dissolving a plurality of coating liquid constituent solutions, a mixing process for mixing them to prepare a coating liquid, a degassing process for the liquid, and separating a large-diameter bubble of the mixed liquid. A coating liquid adjustment defoaming method having a primary defoaming process for removing and a secondary defoaming process for irradiating ultrasonic waves to a pressurized liquid obtained by pressurizing the liquid after the primary defoaming to dissolve small-diameter bubbles,
After dissolving the constituent liquid, the liquid is passed through the thin film casting and depressurizing device respectively or simultaneously, and after performing the degassing process and the primary defoaming process, the secondary defoaming process is performed through the mixing process. A method of adjusting and defoaming a coating solution. 3. A dissolving process for dissolving a plurality of coating liquid constituent solutions, a mixing process for mixing them to prepare a coating liquid, a degassing process for the liquid, and separating a large-diameter bubble of the mixed liquid. A coating liquid adjustment defoaming method having a primary defoaming process for removing and a secondary defoaming process for irradiating ultrasonic waves to a pressurized liquid obtained by pressurizing the liquid after the primary defoaming to dissolve small-diameter bubbles,
After passing the dissolving process through the dissolving process and adding it down to a mixing vessel under reduced pressure to perform the degassing process and the mixing process, the primary degassing device configured by a centrifugal separator or a thin film casting and depressurizing device. A method of preparing and applying a coating solution, wherein the secondary defoaming process is performed through a foaming process. 4. A dissolving process for dissolving a plurality of coating liquid constituent liquids, a mixing process for mixing and adjusting them into a coating liquid, a liquid degassing process, and separating a large-diameter bubble of the mixed liquid. A coating liquid adjustment defoaming method having a primary defoaming process for removing and a secondary defoaming process for irradiating ultrasonic waves to a pressurized liquid obtained by pressurizing the liquid after the primary defoaming to dissolve small-diameter bubbles,
The deaeration process and the primary defoaming process are continuously performed in a thin film casting decompression treatment device through the dissolving process and the mixing process, and then the secondary defoaming process is performed. Coating liquid adjustment defoaming method. 5. The method for adjusting and defoaming a coating solution according to claim 1, wherein the temperature of the liquid is lowered between the secondary defoaming process and the coater. 6. The method according to claim 1, wherein the coating liquid is a coating liquid for a photographic light-sensitive material. 7. The method according to claim 1, wherein the coating liquid is applied by a curtain coating coater.