JP4024566B2 - Airflow pulverizer / classifier - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for efficiently producing toner powder having a sharp particle size distribution by suppressing the mixing of fine powder and coarse particles.
[0002]
[Prior art]
Conventionally, as a method for pulverizing and classifying toner, a combination of two sets of one classifier and one pulverizer, or a combination of two classifiers and one pulverizer is known. As an example, a jet mill, which is a so-called jet type pulverizing means, in which a high-pressure air stream is ejected from a jet nozzle, raw material particles are entrained in the jet air stream, and pulverization is performed by mutual collision of particles or collision with a wall or other collision object. The pulverizing means 1 to 2 and the coarse powder classification means 2 are combined, and after being subjected to pulverization, the classification means 2 are combined to finely classify.
[0003]
1 and 2 are examples of conventional flows. Of these, FIG. 1 will be described. The pulverized raw material 1 is supplied through a raw material supply pipe, and the raw material together with the pulverized material is introduced into the first classifier 2 and divided into coarse powder and fine powder. The coarse powder is pulverized by a first pulverizer 3 equipped with a pulverizing means, once collected by a cyclone 4, and again introduced into the second classifier 5 to be divided into pulverized powder and fine powder. The coarse powder is pulverized by a second pulverizer 6 equipped with pulverizing means and collected by a cyclone 7. Then, the coarse powder is again divided into fine powder and fine powder by the third classifier 8, and the coarse powder is collected as a product by 9, and the fine powder is once collected by the collecting cyclone 10, and further converted into coarse powder and fine powder by the fourth classifier 11. The coarse powder is again collected by the classifier 8 and the fine powder is recovered by the cyclone 12 as the fine powder 13. The ultrafine powder recovered from the dust collector from the classifier or from the upper part of the cyclone 14 and 13 are compacted and granulated and re-kneaded in FIG. 3 offline.
[0004]
However, in this system, the powder supplied to the classification means is not only the raw material powder, but also toners of various particle sizes in the pulverization process are circulated and supplied between the pulverization means and the classification means. In order to obtain the target particle size, the particle size is very broad, and it is operated under a very heavy load. Therefore, the classified product has a large number of coarse particles that adversely affect the quality.
On the other hand, on the coarse powder side that is returned to pulverization again, many fine powders that do not need to be further pulverized are mixed and these fine powders are further pulverized, so the proportion of fine powder in the pulverized product increases. In some cases, agglomerates of fine powder may be generated, and the yield is low even if a desired particle size is obtained by removing the fine powder in the subsequent classification step. In addition, as described above, the ratio of coarse powder, fine powder, etc. increases, and the particle size distribution becomes broad. Therefore, the image obtained using the developer thus produced has a low density and a high charge amount. Not stable.
In other words, the excessively pulverized toner that affects the charge amount of the toner causes a scumming phenomenon, and the insufficiently pulverized toner causes poor transfer and deteriorates the image quality. Further, in production, since an excessive load is applied to the classifier, there is a problem that classification efficiency is low and energy efficiency of pulverization is low.
[0005]
[Problems to be solved by the invention]
In recent dry toners, digitization has progressed with the aim of high image quality, and a sharp particle size with less excess fine particles and coarse particles mixed is required for the control of the particle size, that is, the toner required particle size. In the conventional pulverization process, the energy consumption in the pulverization step is large and it cannot be said that the method is economically advantageous. In addition, in the pulverization by the jet type pulverizer, the generation of fine powder unnecessary as a product is considerably large at 15 to 50% in number ratio, which is likely to cause the fine powder to be mixed into the product toner and to remove the fine powder. The production efficiency is low, and additional energy is required to reuse the removed fine powder. Furthermore, the conventional fine pulverizers have not only insufficient pulverization performance in terms of pulverization processing capacity and power consumption, but also have a problem of adversely affecting the charge amount distribution due to unsatisfactory particle size and distribution in terms of image quality. there were.
[0006]
The present invention is intended to solve the above-mentioned problems, and the object of the present invention is to easily suppress the mixing of excess fine powder and coarse powder with respect to the target particle size, and to make it possible to efficiently reuse the generated excess fine powder. It is an object of the present invention to provide a method suitable for producing a dry toner that can improve the power consumption.
[0007]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have provided a means for promoting the separation of the cyclone that separates the fine powder in the airflow type pulverizer / classifier, thereby performing the separation more reliably and being accompanied by the coarse powder. The amount of fine powder pulverized more than necessary by the pulverizer after the process is reduced as much as possible, thereby improving the classification accuracy and suppressing the fine powder content and fine powder generation rate, and also in terms of production efficiency As a result, the present invention was found.
[0008]
That is, the present invention
A cyclone for collecting (1) finely ground and coarse ground and classified up, the ultra fine powder separating enhancing means in the range amount of from 11 to 14% content of 4μm or less fine powder generated during crushing, the ultrafine powder a air flow type pulverizing and classifying machine cyclone provided with upper tube for recovering, said ultra fine powder piping for flowing the forced air into the cyclone is provided as a separation promotion means, the outlet opening cyclone upper tube of the tubing Airflow crushing and classifying machine characterized by being suitable for.
(2) The airflow pulverizing / classifying machine according to (1), wherein forced air is introduced into the cyclone to control a flow rate.
(3) In the airflow type pulverizer / classifier according to (1) or (2), a dust collector blower communicating with a cyclone for collecting fine pulverization / classification is provided, and the static pressure is -1500 mm to -4000 mm / An airflow type pulverizer / classifier characterized by being Aq.
(4) The airflow pulverization / classification apparatus according to any one of (1) to (3), wherein the coarse powder classified by the classifier is returned to the main raw material side. Machine.
(5) The airflow pulverization / classification apparatus according to any one of (1) to (3), wherein the coarse powder classified by the classifier is returned to the pulverizer side. Machine.
(6) the (1) to (5) in a gas stream pulverizing and classifying machine according to any one of, returning the ultrafine powder was collected in a cyclone or precipitator After granulation, this to the main feed side Airflow type pulverizer / classifier.
(7), characterized in (1) to (5) a gas stream pulverizing and classifying machine according to any one of, after granulating the ultra fine powder was collected in a cyclone or dust collector, to return to the crusher side The present invention relates to an airflow type pulverizing / classifying machine.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
The airflow type pulverizer / classifier of the present invention is basically a pulverizer, a classifier for classifying the pulverized particles, and the finely pulverized / coarse powder classification, ie, pulverized / classified pulverized product. It consists of a cyclone that collects. It is important that the cyclone is provided with means for promoting the separation of ultrafine powder.
In the present invention, as the separation promoting means, it is preferable to provide a rotor, an air inflow portion, an air forced inflow piping and the like in the cyclone. It is also useful to control the blower static pressure of the dust collector communicating with the cyclone and to make the inner cylinder diameter of the cyclone freely changeable.
By providing such separation promoting means in the cyclone, the swirl flow inside the cyclone can be controlled. As a result, the present invention can improve the classification accuracy and reduce the content of coarse powder and fine powder, and a high-quality toner can be obtained using this apparatus.
In the present invention, a step of reusing the separated and recovered ultrafine powder by compaction can be added to the pulverizer / classifier. In this case, the following advantages can be obtained as compared with the case where the conventional granulation step shown in FIG.
A. B. The molecular weight distribution of the resin component in the ultrafine powder does not change. C. Low energy cost compared to reconsideration D. Since the amount of ultrafine powder generated is constant, the flow rate of fine powder flow is constant and the quality is stable. Since the amount of ultrafine powder generated is less than 20% of the amount of toner product, the granulating machine can be small (small production machine).
Embodiments of the present invention will be described with reference to the drawings.
FIG. 5 shows a first embodiment of the present invention. In this embodiment, in the pulverizing / classifying machine shown in FIGS. 1 and 2, the ultrafine powder generated in the pulverization and classified in the classified coarse powder is separated on the upper part of the cyclones 4, 7, and 10. Rotors 4a, 7a and 10a to be promoted are provided. As shown in FIG. 4, this rotor is configured to control and drive the rotational speed of the rotor by motors 4b, 7b and 10b. The number of rotors can be selected according to the required toner specifications, and the peripheral speed of the rotor can be freely controlled to, for example, 10 to 50 m / s.
The pulverizer is a pulverizer using compressed air. For example, the I-type mill pulverizer manufactured by Nippon Pneumatic Co., Ltd., and the classifier is a swirling air flow type, and the pulverization classification is performed using, for example, DS class manufactured by Nippon Pneumatic Co. Can do.
[0011]
An example using this apparatus is shown below.
Example 1 (Reference Example)
A mixture of 75% by weight of a polyester resin, 10% by weight of a styrene acrylic copolymer resin and 15% by weight of carbon black was melt-kneaded with a roll mill, cooled and solidified, and then coarsely pulverized with a hammer mill. In the flow shown in FIG. 5, the cyclone shown in FIGS. 4 and 7 is used as a cyclone in which the rotor 4a shown in FIG. 4 is controlled to a peripheral speed of 25 m / s and the rotor 7a is controlled to be 30 m / s. When pulverization and classification were performed with a raw material supply of 80 kg / hr in the flow, the weight average particle size was 7.5 μm and the fine powder content was 12 POP. %, A particle size of 16 μm or less, and 85% toner particle diameter with a weight average of 1.0 Vol% was obtained.
A multisizer manufactured by Coulter Counter was used for the particle size measurement.
[0012]
Comparative Example 1
The same kneaded product as in Example 1 was used as a toner raw material, but the pulverization and classification were carried out in the same manner as in the process flow shown in FIG. 1 in which no rotor was provided in the cyclone. 7.5 μm diameter and 4 μm or less fine powder content is 17 POP. %, A particle diameter of 16 μm or less, and 80% toner particle diameter with a weight average of 2.5 Vol% was obtained. Thus, in the aspect of Example 1, the classification accuracy is improved compared to the conventional method, the content of fine powder mixed in the product is reduced, and at the same time, the generation rate of fine powder can be suppressed, and the production efficiency is also improved. Are better.
[0013]
Example 2 (Reference Example)
In this embodiment, as shown in FIG. 8, in a conventional airflow crusher / classifier, a cyclone is installed in FIG. 6 and in the cyclones 4, 7, 10 as shown in FIG. A cyclone provided with portions 4c, 7c and 10c through which the next air can flow is installed.
[0014]
In this airflow type pulverizer / classifier, by installing the portions 4c, 7c, and 10c into which the secondary air can flow into the cyclones 4, 7, and 10, the outside air is introduced and the cyclone inside the cyclone is centrifuged. By controlling the force and centripetal force, it is possible to more effectively separate the ultrafine powder generated during pulverization. That is, the ultrafine powder passes through the cyclone upper tube and can be recovered at 14-1, 14-2, and 14-3. As shown in the cross-sectional view of FIG. 7, the secondary air inlet installed in the cyclone is configured to be able to flow uniformly from the outer periphery of the cyclone, and the amount of air is 1 to 50% of the total air volume sucked by the conventional cyclone. Adjustment is possible. Depending on the toner specifications, 1 to 3 cyclones can be installed in the airflow pulverizer / classifier. The pulverizer used in this example is a pulverizer using compressed air, for example, an I-type mill pulverizer manufactured by Nippon Nutic Co., Ltd., and a classifier is a swirling air flow type, for example, DS classification manufactured by Nihon Pneumatic Co., Ltd. Can be used.
[0015]
Examples (reference examples) using this airflow type pulverizer / classifier are shown below.
7 is controlled by the secondary air inflow type cyclone 4a shown in FIG. 6 so that secondary air can flow through the cyclone (suction) 10% of the total air volume in the flow of FIG. When pulverization and classification were performed with a raw material supply of 80 kg / hr in the flow, the weight average particle size was 7.5 μm and the fine powder content was 13 POP. %, A particle diameter of 16 μm or less, and a toner particle size of 1.2% by volume on a weight average basis was 84%.
[0016]
Example 3
In this mode, as shown in FIG. 10, pipes 4d, 7d, and 10d in which forced air can flow into cyclones 4, 7, and 10 are installed as cyclones in a conventional airflow crushing and classifying machine. Is. In this embodiment, in order to improve the efficiency of separating the ultra fine powder generated during pulverization, compressed air is introduced by the piping shown in FIG. 9 to control the centrifugal force and centripetal force inside the cyclone, and the ultra fine powder passes through the upper cyclone tube by the air inflow. 14-1, 14-2, and 14-3.
Note that the air amount of the compressed air pipe attached to the cyclone can be adjusted by 1 to 50% of the total air amount sucked by the conventional cyclone, and one to three cyclones can be installed according to the toner specifications. Further, the pulverizer is a pulverizer using compressed air, for example, an I-type mill pulverizer manufactured by Nippon Nutic Co., Ltd., and the classifier can be a swirling air flow type, such as a DS classifier manufactured by Nihon Pneumatic Co., Ltd.
[0017]
Examples using this airflow type pulverizer / classifier are shown below.
A toner raw material similar to that in Example 1 was a secondary air inflow type cyclone shown in FIG. 9 as a cyclone in the flow of FIG. Control was performed so that secondary air of 10% of the total air volume of the cyclone passing (suction) could flow in, and pulverization classification was performed with the raw material supply of 80 kg / hr in the flow of FIG. A fine powder content of 4 μm or less is 14 POP. %, A particle size of 16 μm or less, and 85% toner particle diameter with a weight average of 1.2 Vol% can be obtained.
In the embodiments shown in Examples 2 and 3 above, the fine powder content mixed into the product is reduced due to the improved classification accuracy compared to the conventional method, and at the same time, the generation rate of fine powder can be suppressed, and the production efficiency is also improved. Are better. Further, the cost required for remodeling the cyclone is lower than that of the first embodiment, which is advantageous.
[0018]
Example 4
In this mode, the controller 4e that can control the flow rate of air flowing into the pipes 4d, 7d, and 10d that can be forced into the air flow type pulverizer / classifier used in the third embodiment as shown in FIG. , 7e, 10e and adjusting valves 4f, 7f, 10f are installed, compressed air is introduced into the fine powder generated during pulverization by the layout configuration shown in FIG. 10, and the centrifugal force and centripetal force inside the cyclone can be precisely controlled. The separated ultrafine powder is configured to pass through the cyclone upper tube by air inflow and be recovered by 14-1, 14-2, 14-3. Note that the air amount of the compressed air pipe attached to the cyclone can be controlled within a range of ± 1 to 10% of the set value by adjusting 1 to 50% of the total air volume sucked by the conventional cyclone. One to three cyclones can be installed according to the toner specifications. In this embodiment, the pulverizer is a pulverizer using compressed air, for example, I-type mill pulverizer manufactured by Nippon Pneumatic Co., Ltd. It can be performed.
In this aspect, since the classification accuracy is improved as compared with the conventional method, the content of fine powder mixed in the product is reduced, and at the same time, the generation rate of fine powder can be suppressed, and the production efficiency is also excellent. Further, the fine powder content can be easily controlled, and a stable toner particle diameter can be obtained over a long period of time.
[0019]
Examples using such an airflow type pulverizer / classifier will be described below.
Using the same toner raw material as in Example 1, the secondary air inflow of 10% of the total flow rate of the cyclone passing (suction) is introduced as a cyclone in the flow of FIG. 10 using the secondary air inflow type cyclone shown in FIG. When the pulverization and classification were performed with the raw material supply of 80 kg / hr in the flow of FIG. 10, the weight average particle size was 7.5 μm and the fine powder content was 13 POP. %, A particle size of 16 μm or less, and a toner particle diameter of 1.1% by volume on a weight average basis was 85%.
[0020]
Example 5
In this aspect, the centrifugal force and centripetal force control of the cyclone used in the above-described embodiment is performed by operating the static pressure of the blower of each dust collector communicating with the cyclone in the range of −1500 to −4000 mm / Aq. . In addition, a clearer effect can be obtained by setting the static pressure of the blower to −1800 to −3500 mm / Aq.
[0021]
Examples using this airflow type pulverizer / classifier are shown below.
Using the same toner raw material and apparatus as in Example 1, the blower static pressure of the dust collector communicating with the cyclone is set to -2500 mm / Aq as the passing static pressure in the cyclone, and pulverization classification is performed by supplying raw materials of 80 kg / hr. As a result, a weight average particle size of 7.5 μm and a fine powder content of 4 μm or less was 11 POP. %, 16 μm or less, and 86% toner particle diameter with a coarse powder content of 1.0 Vol% in weight average could be obtained.
[0022]
Example 6
In this aspect, the cyclone configuration of the airflow crusher / classifier can be changed to 1: 0.1 to 0.5 for the cyclone outer shape and the inner cylinder diameter through which the fine powder passes, and the centrifugal force and centripetal force control in the cyclone can be controlled. It is comprised so that it may carry out. Note that a clearer effect can be obtained by setting the inner diameter of the cyclone to 1: 0.2 to 0.4 with respect to the outer shape of the cyclone.
An example using this apparatus is shown below.
Using the same toner raw material / process flow as in Example 1, the cylinder inner diameter was set to 1: 0.2 with respect to the cyclone outer shape, and pulverization classification was performed by supplying raw materials at 80 kg / hr. .5 μm and 4 μm or less Fine powder content is 12 POP. %, A particle size of 16 μm or less was 85.5% with a toner particle diameter of 1.0 vol% on a weight average.
In the above-described Examples 5 and 6, the classification accuracy is improved as compared with the conventional method, and the content of fine powder mixed in the product is reduced. At the same time, the generation rate of fine powder can be suppressed, and the production efficiency is excellent. Furthermore, it is easy to control the fine powder content, and a toner having a stable particle size over a long time can be obtained.
[0023]
Example 7
In this embodiment, as shown in FIG. 13, the flow diagrams 5, 8, 10, and 12 utilize the third classifier as a coarse powder classifier and are configured to return to the main raw material side to be an airflow type pulverizer / classifier. .
An example using this apparatus is shown below.
Using the process flow shown in FIG. 12 with the same toner raw material as in Example 1, pulverization classification was performed by supplying raw materials at 80 kg / hr. As a result, the weight average particle size was 7.5 μm and the particle content was 12 μP. %, A particle diameter of 16 μm or less, and a toner particle diameter of 85.5% with a weight average of 0.7 Vol% was obtained.
[0024]
Example 8
In this aspect, as shown in FIG. 14 in the process flow diagrams 5, 8, 10, and 12, the third classifier is utilized as a coarse powder classifier, and the airflow type pulverizer / classifier is configured to return to the second pulverizer. It is.
An example using this apparatus is shown below.
When the pulverization classification was performed by supplying the raw materials at 80 kg / hr using the same process flow shown in FIG. 14 with the same toner raw material as in Example 1, the weight average particle size was 7.5 μm and the content of fine powder was 12 POP. %, A particle diameter of 16 μm or less, and a toner particle size of 0.5 vol% on a weight average was 85.5%.
In the embodiments shown in Examples 7 and 8, the classification accuracy is improved as compared with the conventional method, and the content of fine powder and coarse powder mixed in the product is reduced. At the same time, the generation rate of fine powder can be suppressed and the production efficiency is excellent.
[0025]
Example 9
In this embodiment, as shown in FIGS. 15 and 16 in the process flow diagrams 5, 8, 10, 12, 13, and 14, the ultrafine powder collected by the dust collector and the cyclone is granulated (compacted) by 10 to 300 μm on the line. It is an airflow type pulverizer and classifier configured to return to the main raw material side.
This example is shown below.
Using the process flow shown in FIG. 15 with the same toner raw material as in Example 1, the fine powder generated by pulverizing and classifying with the raw material supply of 80 kg / hr was granulated to 200 μm using a granulator roller compactor and moved to the main raw material side. When returned, the weight average particle size was 7.5 μm and the content of fine powder of 4 μm or less was 12 POP. %, And a coarse powder content of 16 μm or less was recovered with a toner particle diameter of 0.5 Vol% on a weight average, and 98.5% could be obtained.
[0026]
Example 10
In this embodiment, as shown in FIGS. 17 and 18, process flow diagrams 5, 8, 10, 12, 13, and 14 are granulated (compact) 10 to 300 μm on the line with ultrafine powder collected by a dust collector and a cyclone. This is an airflow type pulverizer / classifier configured to return to the pulverizer side.
This example is shown below.
Using the process flow shown in FIG. 17 with the same toner raw material as in Example 1, pulverization classification was performed by supplying raw materials at 80 kg / hr, and the generated fine powder was granulated to 200 μm using a granulator roller compactor. When returned, the weight average particle size was 7.5 μm and the content of fine powder of 4 μm or less was 12 POP. %, 16 μm or less, and the coarse powder content was 99.0% recovered with a toner particle diameter of 0.5 Vol% on a weight average.
According to the embodiments of Examples 9 and 10, the classification accuracy is improved as compared with the conventional method, and the content of fine powder and coarse powder mixed in the product is reduced. At the same time, the generation rate of fine powder can be suppressed, and the generated fine powder can be regenerated with less energy than the conventional method, resulting in excellent production efficiency.
[0027]
【The invention's effect】
As described above, according to the present invention, the ultrafine powder can be efficiently separated and recovered from the cyclone, so that the classification accuracy is improved and the content of fine powder mixed into the product can be reduced. At the same time, the generation rate of fine powder can be suppressed and the production efficiency is excellent.
In addition, the toner obtained using the pulverizer / classifier of the present invention has a sharp particle size distribution, so the toner charge amount is also stable. An image with a high image quality can be formed.
[0028]
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a conventional airflow type pulverizer / classifier.
FIG. 2 is an explanatory view showing another conventional pulverizer / classifier.
FIG. 3 is an explanatory diagram of a process of reusing fine powder in FIGS.
FIG. 4 is an explanatory diagram of a cyclone provided with a rotor used in the present invention.
FIG. 5 is an explanatory view showing an embodiment of a pulverizer / classifier according to the present invention.
FIG. 6 is an explanatory diagram of a cyclone provided with a portion into which secondary air used in the present invention can be introduced.
7 is a cross-sectional explanatory view taken along line AB in FIG. 6;
FIG. 8 is an explanatory view showing another embodiment of the pulverizer / classifier of the present invention.
FIG. 9 is an explanatory diagram of a cyclone provided with a pipe through which forced air used in the present invention can flow.
FIG. 10 is an explanatory view showing still another embodiment of the pulverizer / classifier of the present invention.
FIG. 11 is an explanatory diagram of a cyclone provided with a controller and an adjustment valve for controlling the inflow air flow rate used in the present invention.
FIG. 12 is an explanatory view showing still another embodiment of the pulverizer / classifier of the present invention.
FIG. 13 is an explanatory view showing still another embodiment of the pulverizer / classifier of the present invention.
FIG. 14 is an explanatory view showing still another embodiment of the pulverizer / classifier according to the present invention.
15 is an explanatory view showing still another embodiment of the pulverizing / classifying machine of the present invention. FIG. 16 is an explanatory view of recycling of fine powder in the pulverizing / classifying machine of FIG.
FIG. 17 is an explanatory view showing still another embodiment of the pulverizer / classifier according to the present invention.
18 is an explanatory diagram of recycling of fine powder in the crushing / classifying machine of FIG.

Claims (7)

A cyclone for collecting the pulverized-coarse pulverization and classification increases, and super-fine powder separating enhancing means in the range content of 11 to 14% of 4μm or less fine powder generated during crushing, to recover the ultrafine powder a provided cyclonic upper tube airflow pulverizing and classifying machine, a pipe for flowing the forced air into the cyclone is provided as the ultra fine powder separation promotion means, the outlet opening of the pipe is oriented in the cyclone top tube An air-flow pulverizer / classifier.   The airflow type pulverizing / classifying machine according to claim 1, wherein forced air is introduced into the cyclone to control a flow rate.   3. An airflow type pulverizer / classifier according to claim 1 or 2, wherein a dust collector blower communicating with a cyclone for collecting fine pulverization / classification is provided, and the static pressure is -1500 mm to -4000 mm / Aq. Airflow type pulverizer / classifier.   The airflow type pulverizing / classifying machine according to any one of claims 1 to 3, wherein the coarse powder classified by the classifier is returned to the main raw material side.   The airflow type pulverizer / classifier according to any one of claims 1 to 3, wherein the coarse powder classified by the classifier is returned to the pulverizer side. In airflow pulverizing and classifying machine according to any one of claims 1 to 5, after granulating the ultra fine powder was collected in a cyclone or dust collector, a gas stream, characterized in that return it to the main feed side Crushing / classifying machine. In airflow pulverizing and classifying machine according to any one of claims 1 to 5, a gas stream and returning the ultrafine powder was collected in a cyclone or precipitator After granulation, the crusher side grinding / Classifier.

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