JP4442100B2 - Coating tank with ultrasonic oscillator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coating liquid tank for storing a coating liquid of a printing machine or a coating machine, and in particular, an ultrasonic stirring using ultrasonic waves to uniformly disperse pigments and solid additives contained in the coating liquid. The present invention relates to a coating liquid tank with a sound wave oscillator.
[0002]
[Prior art]
In order to maintain good color tone and physical properties of the coating film continuously during printing or coating on paper or synthetic resin film, the concentration and composition of the coating solution change over time or cause unevenness. It is important to always stir the coating liquid uniformly so that it does not occur. On the other hand, in order to print a pattern with a special design or to form a coating film having special physical properties or functionality, the particle size of the coating liquid is, for example, several tens of μm or more. Examples of blending pigments and solid additives are increasing. However, these large particle size pigments and solid additives cause sedimentation and aggregation in the coating liquid over time, and color tone, physical properties, functionality, etc. change due to changes in the concentration of the coating liquid. As a problem, it may cause coating defects.
[0003]
In order to prevent sedimentation and aggregation of the above-mentioned pigments and solid additives, the coating liquid tank of a printing machine or coating machine has, for example, an electric motor or compressed air with a shaft attached with a screw-like stirring blade at the tip. It is common to install a rotating blade type stirring device (commonly known as Disper) that is rotated by the force of the above, and continuously stir the coating liquid during printing or coating operations. However, since this rotating blade type stirring device has only one action point of stirring, non-uniform stirring is likely to occur. For example, a pigment or a solid additive in a corner of a coating liquid tank where stirring force is difficult to be applied. It is extremely difficult to completely prevent sedimentation and aggregation.
[0004]
In order to further increase the stirring effect, it is conceivable to increase the rotating blades or increase the number of rotations according to the size of the coating liquid tank. However, in such a method, when printing or coating progresses and the remaining amount of the coating liquid decreases, a part of the rotary blade is exposed on the surface of the coating liquid, or the coating liquid is stirred excessively vigorously. In other words, the coating liquid may scatter and contaminate the surroundings, or only a part of the coating liquid may be vigorously stirred, resulting in uneven stirring. At this time, it is not preferable in terms of cost to prepare an extra coating liquid in order to maintain the liquid amount. On the other hand, it is conceivable to install a plurality of small, low-power rotary blade type agitators so as to be able to cope with the remaining amount of the coating liquid. However, since there are a plurality of stirring devices, there is a problem in that, in addition to the cost and maintenance being complicated, there is a problem that insufficient stirring occurs due to interference between the stirring devices.
[0005]
In addition to the above, the rotary blade type agitator is used, particularly when a two-component curing type coating solution is used. There are problems such as scattering of the liquid, agglomerates causing foreign film defects as a foreign matter, and difficulty in cleaning the stirrer after printing or coating.
[0006]
As a method of preventing sedimentation and aggregation of pigments and solid additives in the coating liquid without using a rotating blade type stirring device, an ultrasonic vibrator is installed in the coating liquid tank or the coating liquid flow path, etc. There is also a proposal of a method for emitting ultrasonic waves (Patent Documents 1, 2, etc.). However, simply radiating ultrasonic waves into the coating liquid may be effective for redispersion of pigments in the coating liquid where the ultrasonic waves were radiated, but pigments in areas where ultrasonic waves are difficult to reach. Therefore, it is not sufficient as a means for preventing a change in the concentration of the entire coating liquid and the generation of foreign matter.
[0007]
[Patent Document 1]
JP 62-136264 A [Patent Document 2]
JP-A-9-131555
[Problems to be solved by the invention]
The present invention solves the above-mentioned problems in the prior art, prevents sedimentation and aggregation of pigments and solid additives in the coating liquid, density changes over time, density unevenness, printing / coating defects due to aggregated foreign matter The purpose of the present invention is to provide a coating liquid tank that can effectively prevent the occurrence of the above.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is configured as follows, and the invention according to claim 1 of the present invention is a coating liquid for continuously supplying a coating liquid to a printing machine or a coating machine. In the tank, it is constituted by a tank bottom surface having two slopes inclined toward the deepest portion located substantially at the center portion, the vicinity of the deepest portion on the two slopes of the bottom surface, and the two slopes A part of the position from the middle part to the shallowest part between the deepest part and the shallowest part, facing each other across the deepest part is composed of diaphragms each connected with one or more ultrasonic oscillators, By the cooperative action of these ultrasonic oscillators, a straight flow that rises from the deepest part of the bottom surface toward the liquid surface is generated, and the coating liquid carried to the liquid surface by the straight flow flows along the liquid surface. Move to the shallowest part at both ends in the width direction In the shallowest part, it descends to the bottom as a downward flow, and further from the bottom of the shallowest part to the deepest part along the slope, so that the right side of the deepest part is clockwise and the left side is counterclockwise. A coating liquid tank with an ultrasonic oscillator, characterized in that the entire coating liquid in the coating liquid tank is agitated by generating a convection of a shape , and the invention according to claim 2 of the present invention is In the coating liquid tank with an ultrasonic oscillator according to the first aspect of the invention, a cooling device is installed on the outer surface of the tank.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
As shown in FIGS. 1 and 2, the coating liquid tank with an ultrasonic oscillator of the present invention has a V-shaped shape in which the bottom surface of the coating liquid tank 1 has a deepest portion at a substantially central portion in the width direction. It is comprised by the two slopes 2 inclined toward this deepest part. The slope of the slope 2 is selected within a range of about 3 to 20 degrees, and is preferably about 10 degrees. Then, one or more ultrasonic oscillators are installed on each inclined surface 2 at positions near the deepest portion of these two inclined surfaces 2 across the deepest portion. The ultrasonic oscillator may be installed in any manner as long as the ultrasonic wave is emitted into the coating liquid 4. Incidentally, as shown in FIGS. 1-2, a portion of the inclined surface 2 at the installation position of the ultrasonic oscillator of the bottom surface is constituted by the vibrating plate 3 connected to the ultrasonic oscillator. In addition, the ultrasonic oscillator (the diaphragm 3 to which the ultrasonic oscillator is connected) is not only from the vicinity of the deepest part on the two slopes 2 but also from an intermediate part between the deepest part and the shallowest part as shown in FIGS. It is also installed at the shallowest part.
[0011]
The required power, frequency, diameter, etc. of the ultrasonic oscillator used in the present invention must be selected according to the capacity of the coating liquid tank 1 and the composition of the coating liquid 4. Although it depends on the conditions, generally, the output of the ultrasonic oscillator is about 0.7 to 4 W / cm ² , the required power is about 50 to 1200 W, the frequency is about 20 to 45 kHz, and the tip diameter of the ultrasonic oscillator is It is about 20-45 mmφ. The ultrasonic oscillator may be used independently, or a diaphragm in which a plurality of ultrasonic oscillators are connected may be used as is well known.
[0012]
In a liquid, when ultrasonic oscillation with an appropriate frequency is performed, a straight flow due to cavitation occurs near the center axis of the vibration surface of the ultrasonic oscillator. In the present invention, in order to use this straight flow for stirring, at least one pair of ultrasonic oscillators is installed on the bottom surface. Then, the one or more pairs of the ultrasonic oscillators are disposed in the vicinity of the deepest part on the two slopes at positions facing each other with the deepest part interposed therebetween. A straight flow rising from the deepest part toward the liquid level is generated. The coating liquid 4 transported to the liquid surface by this straight flow moves to the shallowest part at both end portions in the width direction along the liquid surface, becomes a downward flow at the shallowest part, moves toward the bottom surface, and further shallowest. It goes from the bottom of the part to the deepest part along the slope 2. In this way, symmetric convection is generated clockwise on the right side and counterclockwise on the left side across the deepest portion, and the entire coating solution 4 in the coating solution tank 1 is effectively stirred.
[0013]
In addition, when the coating liquid 4 passes through the vicinity of the ultrasonic oscillator near the deepest portion, it undergoes an intense dispersion action due to the ultrasonic waves, so that aggregation of pigments and solid additives dispersed in the coating liquid 4 is extremely generated. Even if the pigment and solid additive may aggregate and settle in the shallowest part or the intermediate part between the shallowest part and the deepest part, the aggregated particles that have settled are affected by the action of gravity and convection. Then, it is carried to the deepest part below the slope, where it is re-dispersed by a strong dispersing action by ultrasonic waves, and the sedimentation of the aggregated particles is eliminated. In this way, the formation of coarse particles due to aggregation of pigments and solid additives in the coating liquid 4 is prevented, and the phenomenon of generating coating defects as foreign matters is prevented, and the concentration change of the coating liquid 4 due to sedimentation of the aggregated particles is also prevented. Therefore, a coating film having a stable color tone and physical properties can be obtained even if printing and coating operations are performed continuously for a long time.
[0014]
As shown in FIGS. 3-4, (vibrating plate 3 connected to) ultrasonic oscillator includes a near portion of the deepest portion of the two slopes 2, the shallowest portion from an intermediate portion between the deepest and shallowest portion However, there are the following two methods of using the ultrasonic oscillator installed at this location.
[0015]
First, it is used to prevent the aggregated particles that have settled on the slope 2 at a location far from the deepest part from adhering to the slope 2 and to quickly move to the deepest part on the convection of the coating liquid 4. Is the law. This utilization method is useful under the condition that the convection of the coating liquid 4 is generated at a sufficient flow velocity in the entire interior of the coating liquid tank 1, and the output density of the ultrasonic oscillator at that location is near the deepest part. Although it may be smaller than that, it is preferable to transmit the ultrasonic wave to the widest possible area in the slope 2 and it is preferable to install it in the vicinity of the middle part between the deepest part and the shallowest part.
[0016]
Second, when the convection of the coating liquid 4 due to the ultrasonic wave of the ultrasonic oscillator installed in the vicinity of the deepest part does not sufficiently reach the shallowest part at both ends in the width direction of the coating liquid tank 1. It is an effective method of use, and the ultrasonic oscillator installed at the location from the middle part to the shallowest part also causes the coating liquid 4 to generate a straight flow that rises toward the liquid surface. Another convection is generated. In this case, it is preferable that the ultrasonic oscillator is installed near the shallowest part and the ultrasonic wave is emitted with an output substantially equal to that installed near the deepest part. In this way, the two convections, the convection rising at the deepest part and descending at the intermediate part, and the convection rising at the shallowest part and descending at the intermediate part are symmetrical with respect to the deepest part, that is, a total of 4 Two convections occur, of which the two convections on the deepest side are near the deepest part, and the two convections on the shallowest part are near the shallowest part. The pigment and solid additives in the coating liquid 4 are dispersed by ultrasonic waves. Receive.
[0017]
The coating liquid tank with an ultrasonic oscillator of the present invention is preferably provided with a cooling device on the outer surface. That is, by providing a cooling device, it is possible to suppress the temperature rise of the coating liquid 4 due to the heat generated by the ultrasonic oscillation, and prevent the coating liquid from drying, alteration, viscosity change, etc., and printing / coating of the coating liquid. Good suitability can be maintained. As a cooling method, it is preferable to use a method of circulating a cooling liquid such as a cold water of about 5 to 10 ° C. or an ethylene glycol / water mixture reaching a minimum of −30 ° C. in some cases. The cooling temperature is preferably controlled so that the temperature of the coating liquid 4 in the coating liquid tank 1 is about 25 ° C. or less.
[0018]
【Example】
EXAMPLES Examples and comparative examples of the present invention will be described below with reference to the drawings, but the contents of the present invention are not limited to these.
[0019]
<Example 1>
As shown in FIGS. 1 and 2, the outer shape has a depth of 40 cm, a width of 60 cm, and a depth of 40 cm at the deepest part, and the bottom surface has a slope of 10 from the shallowest part at both ends in the width direction toward the deepest part at the center in the width direction. A total of four diaphragms 3 with three ultrasonic oscillators connected to the coating liquid tank 1 having the slope 2 of the degree so that two pairs face each other across the slope 2 near the deepest part. A coating liquid tank with an ultrasonic oscillator was prepared.
[0020]
Pearl ink (solvent: ethyl acetate / 2-butanone = 1/1, viscosity: Zahn cup # 3, 25 with pearl ink in which a titanium oxide-coated mica particle having a particle size of 15 μm is dispersed as a pigment in a resin varnish in the coating liquid tank. 60 liters), and stirring for 30 minutes while driving the ultrasonic oscillator at a frequency of 28 kHz and an output of 600 W, precipitation and retention of the pigment that would cause a coating problem were not observed.
[0021]
<Example 2>
As shown in FIGS. 3 to 4, the diaphragm 3 having three ultrasonic oscillators connected to the coating liquid tank 1 having the same outer shape as that used in the first embodiment is arranged near the deepest part and the shallowest part. In addition, a coating liquid tank with an ultrasonic oscillator was prepared, in which a total of eight pairs were installed with each pair sandwiching the deepest part.
[0022]
The same amount of the same pearl ink as that used in Example 1 was put into the coating liquid tank 1 and stirred for 30 minutes while driving the ultrasonic oscillator at a frequency of 28 kHz and an output of 1200 W. No stagnation was observed. However, since heat generation due to ultrasonic waves was remarkable, the coating liquid tank 1 was sealed and the cooling pipe provided on the outer surface of the coating liquid tank 1 was cooled by circulating cooling water at a temperature of 5 ° C. .
[0023]
<Comparative Example 1>
The same amount of the same pearl ink as that used in Examples 1 and 2 above is applied to the coating liquid tank having the same external shape as that used in Examples 1 and 2 and having no ultrasonic oscillator. The mixture was stirred for 30 minutes while driving a conventional rotary vane stirrer (disper) with compressed air at a rotation speed of 150 rpm, and the retention of pigment settled in the corner of the coating liquid tank was observed. Aggregated particles of pigment were observed inside, and it was no longer suitable for coating.
[0024]
【The invention's effect】
As described above, according to the coating liquid tank with an ultrasonic oscillator of the present invention, it is possible to prevent uneven stirring of the coating liquid in the coating liquid tank, and to aggregate or settle the pigment and solid additive in the coating liquid. The coating solution can be dispersed evenly and constantly to prevent concentration changes, and the generation of coarse particles due to agglomeration can also be prevented to maintain the coating liquid in excellent quality during printing and coating. It is possible to stably produce high-quality printed and coated products having uniform density and physical properties and no defects.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an example of a coating liquid tank with an ultrasonic oscillator according to the present invention.
FIG. 2 is a plan view of the coating liquid tank with an ultrasonic oscillator shown in FIG.
FIG. 3 is a cross-sectional view of another example of a coating liquid tank with an ultrasonic oscillator according to the present invention.
4 is a plan view of the coating liquid tank with an ultrasonic oscillator shown in FIG. 3. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Coating liquid tank 2 Slope 3 Diaphragm which connected ultrasonic oscillator 4 Coating liquid

Claims (2)

In a coating liquid tank for continuously supplying a coating liquid to a printing machine or a coating machine, it is constituted by a tank bottom surface having two inclined surfaces inclined toward the deepest portion located substantially at the center portion. A portion of the two slopes in the vicinity of the deepest part and a part of the two slopes from the middle part to the shallowest part of the two slopes facing each other across the deepest part. Each of which is constituted by a diaphragm connected with one or more ultrasonic oscillators, and by the cooperative action of these ultrasonic oscillators, a straight flow rising from the deepest part of the bottom surface toward the liquid surface is generated, The coating liquid carried to the liquid surface by the straight flow is moved along the liquid surface to the shallowest part at both ends in the width direction, and is directed to the bottom surface as a downward flow at the shallowest part. To the deepest part along the slope, The clockwise to the right across the deepest part I, on the left by generating the convection symmetrical counterclockwise, characterized in that the entire coating liquid of the coating liquid in the tank has to be agitated Liquid tank with ultrasonic oscillator.   The coating liquid tank with an ultrasonic oscillator according to claim 1, wherein a cooling device is installed on the outer surface.

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