JP2014079690A - Device of collecting powder and method of collecting powder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device of collecting powder and a method of collecting powder which collect highly-adhesive powder by a bag type filter without clogging, especially which use the long-life bag type filter which does not clog even when continuously collecting the powder.SOLUTION: A device of collecting powder includes a plurality (n pieces) of bag type filter elements in a casing, and one common inlet port communicating to the bag type filter elements. An internal outlet side of the bag type filter elements is divided into n rooms, one for each filter element. An outlet of each room communicates to common exhaust means, clean air intake port, and backwash pulse air tank through an opening/closing valve. A method of collecting powder uses the device.

Description

  The present invention relates to a powder recovery apparatus and a powder recovery method.

  Bag filters have been used in the past to collect powder. Various devices have been developed to periodically remove dust without clogging the dust collected by the bag filter. Patent Documents 1 to 3 are known as such conventional techniques.

  Patent Document 1 discloses a filtration type dust removal method for high-temperature and high-pressure exhaust gas. In this dust removal method, the inner outlet side of a bag-type dust collection container containing a plurality of furnace bodies is divided into a plurality of rooms, and the outlets of each room are respectively connected to clean gas headers and backwashing gas headers via valves. The clean gas header is communicated with the backwashing gas header via the booster blower, and dust collection and backwashing (cleaning) are selectively performed for each room by operating the valve at the room outlet. .

  Patent Document 2 discloses a self-supporting bug filter. The bag filter is divided into a chamber A and a chamber B by a partition plate 1 and is composed of two sets of bag filters. The exhaust gas is introduced into the A chamber and the B chamber from the gas inlet pipe, and dust is removed by the filter element. The A chamber and the B chamber are connected to each other via an open / close valve and a switching three-way valve, respectively, to the ejector nozzle and the decompression chamber. For example, when the B chamber is backwashed, the cleaned gas is flowed to the ejector nozzle while the A chamber is in an operating state, and the B chamber is stopped and communicated with the decompression chamber of the ejector to reduce the pressure. Thereafter, the on-off valve is opened, and the cleaning gas from the A chamber is caused to flow into the B chamber and backwashed with the gas.

  Patent Document 3 discloses a semiconductor gas abatement apparatus. Reattachment is reduced by adding a function to stop the exhaust means during backwashing of the bag filter, or a function to reduce the pressure difference between the primary and secondary sides of the bag filter by providing an air intake means in front of the exhaust means. You are doing. Further, it is assumed that a removal nozzle for removing dust and the like on the primary side of the bag filter is added to the primary side of the bag filter, and these additional functions are combined.

JP-A-61-153121 JP-A-8-131741 Japanese Patent Laid-Open No. 10-24207

  The problem to be solved by the present invention is to provide a powder recovery apparatus and a powder recovery method for recovering a powder having strong adhesion without clogging with a bag type filter. Another problem is to provide a powder recovery apparatus and a powder recovery method using a long-life bag filter that does not clog even when powder is continuously recovered.

The above problems have been solved by the following means <1> and <4>. The preferred embodiments are listed below together with <2>, <3>, <5> and <6>.
<1> A plurality (n) of bag-type filter elements are accommodated in the casing, and have a common inlet communicating with the bag-type filter element, and the inner outlet side of the bag-type filter element is the filter element. Powder divided into n rooms, each having an outlet connected to a common exhaust means, a clean air inlet, and a backwash pulse air tank via an on-off valve Body recovery device,
<2> The powder recovery apparatus according to <1>, wherein the bag-type filter element includes a vibration applying unit.
<3> The powder recovery apparatus according to <1> or <2>, wherein the powder recovery apparatus is for recovery of toner for developing an electrostatic image.
<4> In the powder recovery apparatus according to <1> or <2>, the outlet of each room of the plurality (n) of bag-type filter elements housed in the casing and the common exhaust means are communicated with each other. Open all the exhaust on / off valves, powder recovery process for collecting powder for a predetermined time by all n bug type filter elements, then select a specific bug type filter element from n bug type filter elements, The powder recovery by the specific bag type filter element is suspended by closing the exhaust opening / closing valve that connects the outlet of the specific room located on the internal outlet side of the specific bag type filter element and the common exhaust means. And opening the clean air on-off valve that communicates the outlet of the specific room and the clean air intake port to the specific bag-type filter element. The specific bag type filter element is opened by instantaneously opening a backflow process for backflowing clean air from the interior of the nozzle, and a pulse on-off valve communicating the outlet of the specific room and the air tank for the backwash pulse. The specific bag-type filter element cleaning step for performing the pulse back-washing step for performing pulse back-washing, and the above-mentioned cleaning step are sequentially repeated for the remaining (n-1) bag-type filter elements. Powder recovery method,
<5> The powder recovery method according to <4>, wherein vibration is applied to the bag type filter element to be cleaned in the cleaning step,
<6> The powder recovery method according to <4> or <5>, wherein the toner for developing an electrostatic image is recovered.

According to the invention described in <1> above, a powder recovery apparatus having a long replacement life of the bag-type filter element can be provided without interrupting the powder recovery operation using the bag-type filter.
According to the invention described in the above <2>, a clogging is prevented more efficiently than when no vibration applying means is provided, and a powder recovery apparatus with a longer element replacement life is provided.
According to the invention described in the above <3>, a powder recovery apparatus having a long filter life even when recovering a toner for developing an electrostatic image having strong adhesion is provided.
According to the invention described in <4>, there is provided a powder recovery method capable of cleaning each bag type filter without interrupting the powder recovery operation by the bag type filter.
According to the invention described in <5> above, a powder recovery method is provided in which powder recovery is more effective than when no vibration applying means is provided.
According to the invention described in <6> above, a powder recovery method is provided in which the electrostatic charge developing toner is recovered with a longer filter life.

It is an arrangement drawing showing an example of arrangement of equipment in a powder recovery device of this embodiment. Moreover, it is an example which shows a cleaning process typically, and is an example of the powder recovery process which showed the process which is performing the cleaning process with the left filter element, and is performing the powder recovery with the remaining two filter elements. It is. An outline of the configuration of an example of a loop type airflow drying apparatus that may be used in combination with the powder recovery apparatus of the present embodiment is shown.

The powder recovery device (also simply referred to as “recovery device”) of the present embodiment houses a plurality (n) of bug type filter elements in a casing, and is a common one communicating with the bag type filter element. The bag-type filter element has an inlet, and the inner outlet side of the bag-type filter element is divided into n rooms for each filter element, and the outlet of each room is used for a common exhaust means, a clean air inlet, and a backwash pulse. The air tank is communicated with each other through an on-off valve.
The above embodiment will be described below with reference to the drawings.

FIG. 1 is a layout diagram showing an example of the layout of equipment in the powder recovery apparatus 30 of the present invention.
With reference to FIG. 1, the layout of an example of a powder recovery apparatus will be described.
The powder recovery apparatus 30 of this embodiment stores a plurality (n; n represents a natural number of 2 or more) of bug type filter elements 2 in the casing 1, and the plurality of bag type filter elements. The bag-type filter element 2 is divided into n chambers 6 for each filter element, and the outlets of the chambers are connected to a common exhaust means 10 and clean. The air intake port 14 and the backwash pulse air tank 18 communicate with each other through an on-off valve.
Hereinafter, the “bug type filter element” is also simply referred to as “filter element”.
More specifically, the outlet of each room 6 communicates with the clean air intake port 14 via the backflow on-off valve 12 in addition to communicating with the common exhaust means 10 via the exhaust on-off valve 8. In addition, the air valve 18 communicates with the backwashing pulse air tank 18 through the pulse opening / closing valve 16.

Below, the powder recovery apparatus of this embodiment is demonstrated in detail.
This powder recovery apparatus is used to recover various powders, and the powder to be recovered preferably has an average particle diameter of 0.1 to 1,000 μm, preferably 1 to 100 μm. Preferably, it has a particle size of 1 to 10 μm.
Examples of the collected powder include toner for developing an electrostatic image.

The casing 1 is a container that constitutes the can of the present recovery apparatus, and preferably has pressure resistance, and examples thereof include metal containers such as iron and stainless steel.
It is preferable that the shape of the casing 1 includes a body, a cone-shaped hopper provided at a lower portion thereof, and a lid portion provided with various opening / closing valves at an upper portion thereof. The trunk is preferably cylindrical or prismatic, and the lower part is preferably a cone connected to these. Hereinafter, a conical body will be described as an example. A conical hopper that opens upward (in the vertical direction) is connected to the lower part of the cylindrical casing body, and a powder take-out port 26 for taking out the collected powder is provided at the tip.

The filter body 2 of the casing is provided with n filter elements 2 such that the axial direction thereof is vertical or horizontal. The inner outlet side of these filter elements 2 is divided into n chambers 6 for each filter element. Each room 6 is provided with various open / close valves (8, 12, 16), and through these open / close valves, a common exhaust means 10, a clean air inlet 14, and a backwash pulse air tank 18 are respectively provided. Communicating with
From the common entrance 4, air containing powder is introduced into the casing 1.
The entrance 4 is preferably provided on the side surface of the lower part of the casing body. The inlet 4 is preferably provided around the connecting portion between the lower cone portion of the casing and the cylindrical body, and is preferably provided below the front end of the filter element (down in the vertical direction). The air accompanying the powder flowing in from the inlet 4 passes only through the filter element 2, and the powder adheres to the outer surface of the filter element 2. The air from which the powder has been filtered is discharged to the outside of the powder collection device 30 by the common exhaust means 10 through the chamber 6 connected to each filter element 2 and the exhaust release valve 8.

  In the powder recovery apparatus 30 of this embodiment, a plurality (n) of filter elements 2 are accommodated in the casing 1, and the number n (a positive integer) can be arbitrarily selected.

FIG. 1 schematically illustrates three filter elements. n is preferably 2 or more and 50 or less, and more preferably 4 or more and 40 or less. When n is in the latter range, a recovery device that can smoothly perform the cleaning process in order can be provided.
Further, by setting n to 4 or more and 40 or less, cleaning can be smoothly performed in order for each selected specific filter element while continuously collecting powder. Here, “cleaning” includes cleaning by backflow and backwashing pulses. “Backflow” means flowing in the direction opposite to that in the case of collecting powder through the filter element, that is, sending air from the inside of the filter element to the outside. A “backwash pulse” is a pulsating air flow in the backflow direction. By this backflow and backwash pulse, the adhered powder layer is removed from the filter element and cleaned.

The filter element 2 refers to a bag-shaped filter provided inside the powder recovery device 30. The filter element preferably has a cylindrical “bag shape” with a closed tip. The filter element supports a cylindrical filter medium, and mechanically attaches the powder floating in the air to the surface of the filter medium as the air passes.
Examples of the filter medium include a woven fabric, a nonwoven fabric, and a sintered body of particles. The filter element is preferably used for industrial powder recovery in which the filter medium has a cylindrical shape with a closed end.

As a material of the filter element, a resin sintered body in which a large number of substantially spherical resins are sintered to have a large number of pores can be used. The resin sintered filter element includes a commercial product from Mitsubishi Plastics. Examples of the resin to be sintered include polypropylene (PP) and polyester (polyethylene terephthalate). It is preferable to surface-treat another resin on which the powder to be collected is difficult to adhere to the surface of the resin sintered body. Examples of such surface-treated resins include fluorine-containing resins such as polytetrafluoroethylene (PTFE).
In addition, porous ceramics can be used as the material for the filter element.

  The opening of the filter element is appropriately selected based on the particle size distribution of the recovered powder. When the powder particle size to be collected is in a numerical range of 2 to 5 μm, for example, a filter element having an opening that does not pass through this particle size range is used.

The inner outlet side of the filter element 2 is divided into rooms 6 for each filter element. With this configuration, communication to or disconnection from the exhaust means 10, the backflow clean air inlet 14, and the backwash pulse air tank 18 through the on-off valve communicating with each room is, in other words, for each room. Each filter element is operated independently.
Specifically, in the powder recovery apparatus 30 of the present embodiment, the outlet of each room 6 communicates with the common exhaust means 10 via the exhaust opening / closing valve 8, and the outlet of each room 6 via the backflow opening / closing valve 12. It communicates with the clean air inlet 14 and the outlet of each room 6 communicates with the backwash pulse air tank 18 via the pulse opening / closing valve 16. By operating these on-off valves, either the powder recovery or cleaning process is selected for each filter element.

As the on-off valves of the exhaust on-off valve 8, the back-flow on-off valve 12, and the pulse on-off valve 16, members that can be quickly opened and closed such as electromagnetic valves are preferably used. You may have a means to adjust flow volume suitably.
The exhaust means 10 is preferably provided with an adjusting means that makes the exhaust amount constant per time even if the ventilation resistance of the filter element group changes in the powder recovery process.
Further, in the cleaning process in the powder recovery method described later, the backflow process for the specific filter element and the powder recovery process for the other filter elements proceed in parallel, and therefore flow into the casing by the backflow process. In addition to the amount of air entering the casing from the inlet 4, it is preferable to provide an exhaust amount adjusting means for discharging by the exhaust means.
The clean air inlet 14 is an air inlet through which dust is removed from the air outside the powder recovery apparatus by a filter or the like. The clean air inlet 14 preferably includes a filter for filtering and removing dust in the atmosphere. Clean air is introduced into the casing 1 from the clean air inlet 14 due to the negative pressure inside the casing 1 generated by the exhaust means 10.
The backwash pulse air tank 18 is preferably a pressure tank that stores compressed air. Similarly, the vibration-applying air tank 24 is preferably a tank for storing compressed air, and a known tank is used for its shape and material.
The backwash pulse air tank 18 is a high-pressure air source, and is preferably a pressurized air tank, and its internal pressure is preferably 0.3 to 1.0 MPa.

Opening / closing operation of these exhaust opening / closing valve 8, backflow opening / closing valve 12, pulse opening / closing valve 16, etc., adjustment of the exhaust amount per unit time of the exhaust means 10, pressurized air in the backwash pulse air tank 18 It is preferable to control the pressure, the opening / closing operation of the vibration on-off valve 22 described later, and the like by a control means (not shown). That is, with the passage of time, the opening / closing operation of the on-off valves (8, 12, 16) and the opening time of the pulse on-off valve are programmed in advance, and the exhaust amount per unit time of the exhaust means 10 is also predetermined per unit time. It is preferable to finely adjust the capacity of the exhaust means so that the exhaust amount becomes the same.
In addition, the cleaning air inhalation time and the inhalation amount, the pressure of the backwash pulse air tank, the pulse supply time, the pulse interval and the number of times, the supply amount and timing of the vibration applying air, It is preferable to have a control means for preprogramming and controlling the synchronization pattern and the like.

  In the powder recovery apparatus of this embodiment, it is preferable that the filter element 2 includes the vibration applying means 20. The vibration applying means is appropriately selected and preferably has an action of applying vibrations to the entire filter element to wipe off the powder adhering to the outside of the filter element. The vibration applying means may be any means that applies any one or more of magnetic vibration, mechanical vibration, and electrical vibration. Means for imparting mechanical vibration is preferably used, and a flexible rubber hose is disposed in the vicinity of the filter element, and the hose is vibrated through the vibration on-off valve 22 from outside the casing to vibrate the hose. A mode in which the whole of 2 is shaken and the powder adhering to the outside is shaken off can be exemplified.

  In FIG. 1, the vibration on-off valve 22 communicating with the vibration applying air tank 24 is opened, and the hose itself is vibrated by passing pressurized air through the vibration applying means 20 such as a flexible hose. It is preferable to more reliably wipe off the powder adhering to the outside of the filter element by striking and shaking the adjacent filter element 2. It is preferable that the vibration applying unit 20 applies the vibration in synchronization with the cleaning process. In FIG. 1, the vibration applying means is shown only on the leftmost filter element, but it is preferably provided for all filter elements.

The powder recovery apparatus of this embodiment can be preferably used for recovering electrostatic image developing toner (also simply referred to as “toner”). The powder recovery apparatus of this embodiment can be used for recovery of toner by a so-called kneading and pulverization method, but is preferably used for recovery of toner for electrostatic charge development produced by a so-called agglomeration coalescence method. Since the toner has a strong mutual adhesion property, it is difficult to recover the toner from the accompanying air, but the toner can be recovered without shortening the operation life of the filter element by the recovery device of this embodiment.
When the toner produced by a wet method is collected, the agglomerated toner produced by a wet method may be first dried by an air flow drying device, and then the toner may be collected by the powder collection device of this embodiment.
In the above case, it is preferable to dry the wet toner using a loop type airflow drying device, and subsequently collect the toner with the powder collecting device of the present embodiment. A loop type airflow dryer is disclosed in, for example, Japanese Patent Application Laid-Open No. 2006-39123.

  FIG. 2 shows an outline of the configuration of an example of a loop type airflow drying apparatus. In this airflow drying device, the hot air supplied from the hot air supply device 118 passes through the nozzle 112 and becomes an airflow (hot air) that circulates inside the dryer loop unit 100 at a high speed. The wet particles supplied from the wet particle supply device 117 through the wet particle supply port 113 are dispersed by the air flow and swirl with the air flow inside the dryer loop unit 110, whereby the water in the wet particles is removed and a predetermined water content is obtained. It becomes below the rate, and is conveyed from the classification unit 114 to the powder recovery device 115 of the present embodiment. It is preferable to recover the powder by conveying the powder dried by the loop type airflow drying apparatus to the powder recovery apparatus of the present embodiment.

<Powder recovery method>
In the powder recovery method of the present embodiment, the powder recovery apparatus of the present embodiment described above is used.
The powder recovery method of the present embodiment communicates the outlet of each room of a plurality (n) of bag-type filter elements accommodated in the casing and the common exhaust means in the powder recovery apparatus of the present embodiment. Open the exhaust on-off valve to perform powder recovery process for a specified time with all n bug-type filter elements and then select a specific bug-type filter element from n bug-type filter elements. The powder recovery by the specific bag type filter element is performed by closing an exhaust opening / closing valve that communicates the outlet of the specific room located on the internal outlet side of the specific bag type filter element and the common exhaust means. The specific bug type flow is stopped and the clean air on-off valve communicating with the outlet of the specific room and the clean air inlet is opened. A backflow process for backflowing clean air from the interior of the air filter element, and a pulse opening / closing valve that connects the outlet of the specific room and the air tank for backwashing pulse is opened momentarily, and the specific bag type filter element The specific bag-type filter element cleaning step for performing the pulse back-washing step for performing pulse back-washing, and the above cleaning step for the remaining (n-1) bag-type filter elements are sequentially repeated. To do.

  As described above, the powder recovery method of the present embodiment includes a step of preparing the powder recovery device of the present embodiment, a powder recovery step of recovering powder by all n filter elements, and then a specific filter. A cleaning process in which cleaning is performed in the element, and similar cleaning is sequentially repeated in another specific filter element.

A powder recovery process for recovering powder by all n filter elements will be described. In this powder recovery process, only the powder recovery is performed for a predetermined time by all n filter elements, and no process related to cleaning is performed.
For this reason, as the operation of the valves, all the exhaust on-off valves 8 that connect the outlets of the chambers of a plurality (n) of the bag type filter elements and the common exhaust means are opened. During this time, all of the backflow on-off valve 12, the pulse on-off valve 16, and the vibration on-off valve 22 related to cleaning are closed.

After collecting the powder for a predetermined time, cleaning is performed for each filter element. Cleaning is usually performed sequentially for each one filter element, but this does not exclude performing it for every two filter elements.
During the cleaning process, the powder recovery process is stopped, and the backflow process and the pulse backwashing process are performed in synchronization. It is preferable to apply vibration to the filter element during this cleaning step. The cleaning process for each filter element is sequentially repeated for the remaining (n-1) filter elements.

  More specifically, in the powder recovery method of the present embodiment, a plurality (n; n represents a natural number of 2 or more) of filter elements 2 are accommodated in the casing 1, and the filter element 2 (2- 1,..., 2-i,..., 2-n) have one common inlet 4, and the inner outlet side of the filter element 2 has n chambers 6 (6-1,. , 6-i,..., 6-n), and the outlet of each room 6 is connected to a common exhaust means via exhaust on-off valves 8 (8-1,..., 8-i,..., 8-n). 10, the outlet of each room 6 is communicated with the clean air inlet 14 via the backflow on-off valves 12 (12-1,..., 12-i,..., 12-n), Backwash pulse air tank 18 through pulse open / close valves (16-1, ..., 16-i, ... 16-n) Using the powder recovery device 30 in communication. In the first powder recovery step, a plurality of (n) filter elements (2-1,..., 2-i,..., 2-n) housed in the casing have exhaust means common to the outlets of the respective rooms. All the exhaust on-off valves communicating with 10 are opened, and the powder recovery process is performed for a predetermined time by all n bag-type filter elements. During this time, all the back-flow on-off valves 12, the pulse on-off valves 16, and the vibration on-off valves 22 are shut off.

After performing the powder recovery process in all the filter elements 2 for a predetermined time, the powder recovery process is stopped only for the specific filter element 2-i, and the cleaning process is performed. During this time, the powder recovery process is continued for the other filter elements.
Specifically, the cleaning step is a step of closing the exhaust on-off valve 8-i at the outlet of the chamber 6-i connected to a specific filter element 2-i to stop the powder recovery, the chamber 6-i. The step of opening the back-flow on-off valve 16-i communicating with the air and the step of washing the filter element 2-i with back-flow air, and the time of opening the pulse on-off valve 16-i communicating with the room 6-i, A pulse backwashing process is performed in which the filter element 2-i is backwashed with a pulse.
After performing the cleaning process of the filter element 2-i for a predetermined time, the above cleaning process is sequentially repeated for the remaining (n-1) bug type filter elements.

In the powder recovery process, powder recovery is performed for a predetermined time by all n bug-type filter elements (2-1,..., 2-i,..., 2-n). When the air containing the powder passes through the filter medium constituting the bag type filter element, the powder in the air adheres to the surface of the filter medium and is deposited to separate the powder. As the powder layer adhering to the surface of the filter medium becomes thicker, the airflow resistance increases. This ventilation resistance is detected by a load for exhausting a predetermined amount of air per unit time.
In the powder recovery process, the air containing the powder introduced from the inlet 4 is separated by all the filter elements 2, and only the air excluding the powder passes through each room 6 and is exhausted by the exhaust means 10. It is discharged outside the collection device.

In the cleaning process after the powder recovery process, the recovered powder layer is removed from the outer peripheral surface of the filter element 2 into the casing 1 to recover the powder.
When the air flow resistance of the filter element becomes larger than a certain value due to the powder recovery process, or after a predetermined time has elapsed, the cleaning process is performed and the powder adhered to the outside of the filter element 2 The body is wiped down into the casing 1 in order.
Hereinafter, for convenience of explanation, a specific filter element selected from the n filter elements is referred to as “filter element 2-i”, and a room connected thereto is referred to as “room 6-i”. All the filter elements other than the filter element 2-i are described as “filter element 2-j”, and all the rooms other than the room 6-i are also described as “room 6-j”. 1 ≦ i ≦ n and 1 ≦ j ≦ n, and i ≠ j.

In the above powder recovery method, after a predetermined operating time has elapsed, in order to eliminate clogging of the filter element and recover the powder attached to the outside of the filter element, the powder attached to the outside of the filter element is removed. Remove from the filter element.
For this purpose, the exhaust on-off valve 8-i communicating with the outlet of the room 6-i is closed, and the powder recovery by the filter element 2-i is interrupted. After the powder recovery is interrupted, a cleaning process is performed on the filter element 2-i.
During the cleaning of the i-th filter element, the powder recovery is continued for the i-th filter element 2-j. However, cleaning of two or more filter elements is not excluded.

Specifically, in the cleaning process, preferably, only the filter element 2-i performs the backflow process and the pulse backwashing process at the same time. In the backflow process, the backflow on-off valve communicating with the room 6-i is opened, and clean air is vented from the inside of the filter element 2-i connected to the room 6-i to the casing side.
The amount of ventilation in the powder recovery step can be selected as appropriate, but the average ventilation rate in the casing is preferably a linear velocity of 0.1 to 5 m / min in the axial direction of the body portion of the casing, and 0.3 to 2 m. / Min is preferred.

The aeration amount per hour in the backflow process preferably exceeds the aeration amount per unit time for one filter element in the powder recovery step, and is preferably 1.1 to 1.5 times.
A pulse backwashing process is repeated between the backwashing process (backflow process). The pulse time is preferably 0.005 to 1 second, and more preferably 0.01 to 0.5 second. The backflow air pressure is preferably about 0.2 to 1.0 MPa. The pulse backwashing may be performed only once or multiple times.
Note that it is preferable to synchronize the application of vibration to the filter element described later with the cleaning process.

The cleaning process is preferably performed sequentially for each filter element. For filter elements that are insufficiently cleaned, the cleaning process may be repeated.
In the cleaning process, the amount of clean air introduced into the casing in the backflow process per filter element is preferably equal to or greater than the amount of exhaust by the exhaust means 10 in the powder recovery process.
The powder recovery method of this embodiment is preferably used at 20 to 80 ° C, more preferably at 25 to 60 ° C, and particularly preferably at 25 to 50 ° C. The upper limit temperature is affected by the heat resistance of the powder to be collected and the heat resistance temperature of the material of the filter element.

In the present embodiment, it is preferable to apply vibration to the filter element 2-i in the backflow process in the cleaning process. The vibration is preferably applied to the entire filter element 2-i. Therefore, it is preferable to provide a flexible air tube (air tube) extending in the entire length direction outside the filter element 2-i so as to contact the filter element.
By ventilating the air pipe, the vibration of the air pipe itself causes the vibration of the filter element in contact therewith.

The powder recovery apparatus of this embodiment is preferably used for recovering toner for developing electrostatic images. Although there is no particular limitation on the type of toner, it is preferably used as a recovery device in a drying process of toner manufactured in an aqueous system by a so-called aggregation method.
Hereinafter, the toner produced by the aggregation method will be mainly described.

(toner)
The electrostatic image developing toner collected in this embodiment contains toner base particles containing a binder resin as an essential component and a colorant and a release agent as optional components. The toner base particles may further contain a known additive such as a charge control agent. An external additive is appropriately blended with the toner base particles.

<Binder resin>
Binder resins include polyolefin resins such as polyethylene and polypropylene, styrene resins mainly composed of polystyrene, poly (α-methylstyrene), polymethyl (meth) acrylate, polyacrylonitrile and the like (meta). ) Acrylic resins, styrene- (meth) acrylic copolymer resins, polyamide resins, polycarbonate resins, polyether resins, polyester resins, and copolymer resins thereof, but charging when used as a toner for developing electrostatic images From the viewpoint of stability and development durability, styrene resins, (meth) acrylic resins, styrene- (meth) acrylic copolymer resins and polyester resins are preferred.

As the binder resin, it is preferable to contain a polyester resin from the viewpoint of low-temperature fixability. Generally, a toner having low-temperature fixability is difficult to control the powder behavior and tends to be reduced in recovery. Is suitable for toner recovery. The polyester resin is obtained, for example, mainly by condensation polymerization of polyvalent carboxylic acids and polyhydric alcohols.
Examples of the polyvalent carboxylic acids include aromatic carboxylic acids such as terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid, naphthalenedicarboxylic acid; maleic anhydride, fumaric acid, succinic acid, alkenyl Examples thereof include aliphatic carboxylic acids such as succinic anhydride and adipic acid; alicyclic carboxylic acids such as cyclohexanedicarboxylic acid, and lower alkyl esters and acid anhydrides thereof.

Examples of the polyhydric alcohol include aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentylglycol, and glycerin; cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol And alicyclic diols such as A; aromatic diols such as ethylene oxide adduct of bisphenol A and propylene oxide adduct of bisphenol A. These polyhydric alcohols may be used alone or in combination of two or more.
For the purpose of ensuring better fixing properties, a trihydric or higher polyhydric alcohol (for example, glycerin, trimethylolpropane, pentaerythritol, etc.) is used in combination with a diol to form a crosslinked structure or a branched structure. Also good.

  The glass transition temperature (hereinafter sometimes abbreviated as “Tg”) of the amorphous polyester resin is preferably 50 ° C. or higher and 80 ° C. or lower, and more preferably 50 ° C. or higher and 70 ° C. or lower. A Tg of 80 ° C. or lower is preferable because it has excellent low-temperature fixability. Further, it is preferable that Tg is 50 ° C. or more because it is excellent in heat-resistant storage stability and fixed image storage stability.

  The acid value of the amorphous polyester resin is preferably 5 mgKOH / g or more and 25 mgKOH / g or less, more preferably 6 mgKOH / g or more and 23 mgKOH / g or less. If the acid value is 5 mgKOH / g or more, the toner has good affinity for paper and good chargeability. In addition, when the toner is produced by the emulsion aggregation method described later, it is easy to produce emulsion particles, and it is suppressed that the aggregation rate in the aggregation process of the emulsion aggregation method and the shape change rate in the fusion process are remarkably increased. And shape control is easy. In addition, if the acid value of the amorphous polyester resin is 25 mgKOH / g or less, the environmental dependency of charging is not adversely affected. In addition, it is possible to prevent the aggregation speed in the aggregation process in the toner production by the emulsion aggregation method and the shape change speed in the coalescence process from being remarkably slow, thereby preventing a decrease in productivity.

In the toner collected in this embodiment, the toner base particles may contain a crystalline polyester resin.
Since the crystalline polyester resin lowers the toner viscosity of the polyester resin when melted, a toner having better low-temperature fixability can be obtained. Of the crystalline polyester resins, aromatic crystalline polyester resins generally have a high melting temperature range, which will be described later. Therefore, when the crystalline polyester resin is included, it is more preferably an aliphatic crystalline polyester resin. .

  The toner collected in this embodiment is preferably a toner in which the content of the crystalline polyester resin in the toner base particles is 2 wt% or more and 30 wt% or less, and more preferably 4 wt% or more and 25 wt% or less. When the content is 2% by weight or more and 30% by weight or less, the deterioration of the fluidity of the toner due to the presence of the crystalline polyester resin is prevented, and the recovery is less likely to occur.

  The melting temperature of the crystalline polyester resin is preferably in the range of 50 ° C. or higher and 90 ° C. or lower, and more preferably in the range of 55 ° C. or higher and 90 ° C. or lower. When the melting temperature is 50 ° C. or higher, the toner storage stability and the toner image storage stability after fixing are excellent. Moreover, if it is 90 degrees C or less, low temperature fixability will improve.

The glass transition temperature of the resin may be measured by a known method, for example, the method (DSC method) defined in ASTM D3418-82.
For the measurement of the melting point of the crystalline resin, a differential scanning calorimeter (DSC) is used, and the input compensated differential scanning shown in JIS K-7121 when measuring from room temperature to 150 ° C. at a heating rate of 10 ° C. per minute. It can be determined as the melting peak temperature of calorimetry.
“Crystallinity” as shown in the crystalline resin means that in differential scanning calorimetry (DSC), it has a clear endothermic peak, not a step-like endothermic change. It means that the half-value width of the endothermic peak when measured at a rate of 10 ° C./min is within 15 ° C.
On the other hand, a resin having a half-value width of an endothermic peak exceeding 15 ° C. or a resin in which no clear endothermic peak is observed means non-crystalline (amorphous). The glass transition temperature by DSC of the amorphous resin is measured according to ASTM D3418 using a differential scanning calorimeter (DSC-50) manufactured by Shimadzu Corporation equipped with an automatic tangential processing system. The measurement conditions are described below.
The amount of the sample is 3 to 15 mg, preferably 5 to 10 mg. As a measuring method, a sample is put in an aluminum pan, and an empty aluminum pan is used as a reference. The measurement of the temperature curve is based on the temperature rising condition I (20 ° C. to 180 ° C., temperature rising rate 10 ° C./min).
The glass transition temperature is measured from the endothermic curve measured at the time of temperature rise in the above temperature curve.
The glass transition temperature is a temperature at which the differential value of the endothermic curve is maximized.
The crystalline polyester resin is a polymer obtained by copolymerizing other components with respect to the main chain. When the other components are less than 50% by weight, the copolymer is also called crystalline polyester.

Examples of the acid component used for the synthesis of the crystalline polyester resin include various polycarboxylic acids. Dicarboxylic acids are preferable, and linear aliphatic dicarboxylic acids are more preferable.
For example, adipic acid, pimelic acid, suberic acid, azelinic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1 , 13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc., or lower alkyl esters and acid anhydrides thereof. is not. Of these, adipic acid, sebacic acid, and 1,10-decanedicarboxylic acid are preferable in view of availability.

The alcohol component used for the synthesis of the crystalline polyester resin is preferably an aliphatic diol, such as 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol. 1,10-decanediol, 1,11-dodecanediol, 1,12-undecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, 1,20-eicosanji Examples include all, but not limited to this. Among these, in view of availability and cost, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferable.
There is no restriction | limiting in particular as a manufacturing method of a polyester resin, You may manufacture by the general polyester polymerization method which makes an acid component and an alcohol component react. For example, direct polycondensation, transesterification, and the like are used depending on the type of monomer. The molar ratio (acid component / alcohol component) for reacting the acid component with the alcohol component cannot be generally described because it varies depending on reaction conditions and the like, but is usually about 1/1 for increasing the molecular weight. Is preferred.
Catalysts that can be used in the production of the polyester resin include alkali metal compounds such as sodium and lithium; alkaline earth metal compounds such as magnesium and calcium; metal compounds such as zinc, manganese, antimony, titanium, tin, zirconium, and germanium; Examples thereof include phosphorous acid compounds; phosphoric acid compounds; and amine compounds.

<Colorant>
The toner base particles preferably contain a colorant.
Examples of the colorant used in the toner of the exemplary embodiment include magnetic powders such as magnetite and ferrite, carbon black, lamp black, chrome yellow, hansa yellow, benzidine yellow, sren yellow, quinoline yellow, permanent orange GTR, and pyrazolone orange. , Vulcan Orange, Watch Young Red, Permanent Red, Brilliantamine 3B, Brilliantamine 6B, Dupont Oil Red, Pyrazolone Red, Rizor Red, Rhodamine B Lake, Lake Red C, Rose Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue , Ultramarine blue, methylene blue chloride, phthalocyanine blue, phthalocyanine green, malachite green oxalate, etc. Or acridine, xanthene, azo, benzoquinone, azine, anthraquinone, thioindico, dioxazine, thiazine, azomethine, indico, thioindico, phthalocyanine, aniline black, polymethine, Various dyes such as triphenylmethane, diphenylmethane, thiazine, thiazole, and xanthene can be used singly or in combination of two or more.
In addition, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. And CI Pigment Blue 15: 3.

  The content of the colorant in the toner base particles is preferably in the range of 1 to 30 parts by weight with respect to 100 parts by weight of the binder resin in the toner base particles. It is also effective to use a surface-treated colorant or a pigment dispersant as necessary. By appropriately selecting the type of the colorant, it is possible to obtain a toner that can be used as three primary colors for various color reduction methods, such as yellow toner, magenta toner, cyan toner, and black toner.

<Release agent>
The toner base particles preferably contain a release agent.
There is no restriction | limiting in particular in the mold release agent used for this embodiment, A well-known thing is used and the following waxes are preferable.
Examples thereof include paraffin wax and derivatives thereof, montan wax and derivatives thereof, microcrystalline wax and derivatives thereof, Fischer-Tropsch wax and derivatives thereof, and polyolefin wax and derivatives thereof. Derivatives include oxides, polymers with vinyl monomers, and graft modified products. In addition, alcohols, fatty acids, plant waxes, animal waxes, mineral waxes, ester waxes, acid amides and the like are also used.

<Other additives>
In addition to the above-described components, various components such as an internal additive and a charge control agent may be added to the colored particles as necessary.
Examples of the internal additive include metals such as ferrite, magnetite, reduced iron, cobalt, nickel and manganese, alloys, and magnetic materials such as compounds containing these metals.
Examples of the charge control agent include quaternary ammonium salt compounds, nigrosine compounds, dyes composed of complexes of aluminum, iron, chromium, and triphenylmethane pigments.

The toner base particles of the toner to be collected in the present embodiment are not particularly limited by the manufacturing method, and a known method can be used. Specific examples include the following methods.
The production of the toner base particles is obtained, for example, by a kneading and pulverizing method in which a binder resin, a colorant, a release agent, and a charge control agent, if necessary, are kneaded, pulverized, and classified; To change the shape of the particles by mechanical impact force or thermal energy; dispersion of emulsified binder resin, dispersion of colorant, release agent, and charge control agent as required An emulsion aggregation method (aggregation coalescence method) to obtain toner particles by mixing and agglomerating and heat-fusing the solution; emulsion polymerization of a binder resin polymerizable monomer, and a formed dispersion and colorant , A release agent and, if necessary, a dispersion of a charge control agent, etc., and agglomeration, heat-fusing to obtain toner particles; an emulsion polymerization aggregation method; a polymerizable monomer for obtaining a binder resin Suspend the body and a colorant, a release agent and, if necessary, a solution such as a charge control agent in an aqueous solvent for polymerization. Pollution polymerization; binder resin and a colorant, releasing agent, and dissolution suspension method and granulated with a solution such as a charge control agent is suspended in an aqueous solvent optionally; or the like can be used. In addition, a manufacturing method may be performed in which the toner base particles obtained by the above method are used as a core, and aggregated particles are further adhered and heat-fused to have a core-shell structure.
Among these, the toner of the exemplary embodiment is preferably a wet toner (emulsion aggregation toner) obtained by an emulsion aggregation method or an emulsion polymerization aggregation method.

  The toner base particles produced as described above preferably have a volume average particle diameter in the range of 2 to 8 μm, and more preferably in the range of 3 to 7 μm. When the volume average particle size is 2 μm or more, the toner has good fluidity, and sufficient chargeability is imparted from the carrier, so that fogging in the background portion and density reproducibility are unlikely to occur. . Further, when the volume average particle size is 8 μm or less, the effect of improving the reproducibility, gradation and graininess of fine dots is good, and a high-quality image can be obtained. In addition, the said volume average particle diameter is measured with measuring machines, such as Coulter multisizer II (made by Beckman-Coulter company), for example.

  The toner base particles are preferably pseudo-spherical from the viewpoint of improving developability and transfer efficiency and improving image quality. The sphericity of the toner base particles can be expressed by using the shape factor SF1 of the following formula, but the average value (average shape factor) of the shape factor SF1 of the toner base particles used in this embodiment is 145. Is preferably in the range of 115 or more and less than 140, and more preferably in the range of 120 or more and less than 140. When the average value of the shape factor SF1 is less than 145, good transfer efficiency is obtained and the image quality is excellent.

In the above formula, ML represents the maximum length of each toner base particle, and A represents the projected area of each toner base particle.
The average value of the shape factor SF1 (average shape factor) is obtained by taking 1,000 toner images magnified 250 times from an optical microscope to an image analyzer (LUZEX III, manufactured by Nireco Corporation), and the maximum From the length and the projected area, the value of the SF1 is obtained for each particle and averaged.

Examples of the powder recovery apparatus in the process of drying wet colored particles having a moisture content of 30 to 40% are shown below.
In the drying process, the colored particles dried by the airflow drying device are collected by the powder recovery device, and “Flash dryer” manufactured by Seishin Co., Ltd. was used as the airflow drying device.
Example 1
As a powder recovery device arranged at the subsequent stage of the air flow drying device, in a similar manner to the embodiment shown in FIG. 1, four filter elements are accommodated, and the inner outlet side of each filter element is provided for each filter element. A powder recovery apparatus 1 was prepared that was divided into four rooms and did not have a flexible rubber hose that contacts the filter element.
Here, as the filter element, a surface of polyester (polyethylene terephthalate) coated with a fluororesin was used.

In the powder recovery method of this embodiment, the conditions used were as follows.
(First powder recovery conditions)
Initial powder recovery time: 10 minutes Powder content in air: 1 kg / m ³
Air flow rate: 10 m ³ / min Effective filter area (per one): 9.5 m ² / line (cleaning conditions)
Cleaning time: 60 seconds / line Clean air supply: 2.5 m ³
Backwash pulse air interval: 20 seconds Backwash pulse frequency: 3 times / pulse air pressure: 0.3 MPa
Backwash pulse air discharge time: 0.01 seconds Vibration application time: 10 seconds Backflow air amount per element / recovered air amount: 100%

(Example 2)
In Example 1, a powder recovery apparatus 2 having the same configuration as that of Example 1 was prepared except that a flexible rubber hose was provided so as to contact each of the four filter elements. The flexible rubber hose was made of natural rubber and had an inner diameter of Φ8 mm.

(Comparative Example 1)
In Example 1, four filter elements are accommodated, but the internal outlet side of each filter element is not divided for each filter element, and the powder recovery does not have a flexible rubber hose that contacts the filter element. Apparatus 3 was prepared.

When the toner produced by the agglomeration and coalescence method was recovered by the present powder recovery apparatus and the powder recovery method, the following results were obtained for the filter life.
Here, the recovered toner is obtained by using a poly (styrene-acryl) copolymer described in paragraphs 0049 to 0062 of JP-A-2006-39123 as a binder resin, a black pigment (carbon black), and a release agent ( The toner base particles were agglomerated in an aqueous medium having a volume average particle diameter of about 5.9 μm containing a paraffin wax).

(Filter life evaluation method)
Here, the filter life was expressed in terms of operation time (unit: days) until the pressure difference of the four filters became 1.5 kPa as compared with the time of starting use.
The following results were obtained. Example 1 which is this embodiment showed a filter life 1.5 times longer than that of the comparative example. In Example 2 in which vibration imparting means using a flexible hose was used in combination, the filter life was further doubled.

1: Casing 2: Bag type filter element 4: Entrance 6: Room 8: Exhaust on / off valve 10: Exhaust means 12: Backflow on / off valve 14: Clean air inlet 16: Pulse on / off valve 18: Backwash pulse air tank 20: Vibration applying means 22: Vibration on / off valve 24: Vibration applying air tank 26: Powder outlet 30: Powder recovery device 110: Dryer loop unit 112: Nozzle unit 113: Wet particle supply unit 114: Classification unit 115: Powder Recovery device 116: Powder recovery port 117: Wet particle supply machine 118: Hot air supply machine

Claims (6)

In the casing,
Contains multiple (n) bug-type filter elements,
Having one common inlet communicating with the bug filter element;
The internal outlet side of the bag type filter element is divided into n rooms for each filter element,
A powder recovery apparatus, characterized in that an outlet of each room communicates with a common exhaust means, a clean air inlet, and an air tank for backwash pulse via an on-off valve.   2. The powder recovery apparatus according to claim 1, further comprising vibration imparting means for the bag type filter element.   The powder recovery apparatus according to claim 1, wherein the powder recovery apparatus is for recovering toner for developing an electrostatic image. 3. The powder recovery apparatus according to claim 1, wherein all of the exhaust opening / closing valves that connect the outlet of each room of the plurality (n) of bag type filter elements housed in the casing and the common exhaust means are provided. A powder recovery process in which the powder recovery is performed for a predetermined time by opening all n bug-type filter elements;
An exhaust opening / closing valve that selects a specific bug-type filter element from n bug-type filter elements and communicates the outlet of a specific room located on the inner outlet side of the specific bug-type filter element with the common exhaust means By closing the powder recovery by the specific bag-type filter element and opening the clean air on-off valve that communicates the outlet of the specific room and the clean air inlet, the specific bug A backflow process for backflowing clean air from the inside of the filter element, and a pulse open / close valve that communicates the outlet of the specific room and the air tank for the backwash pulse instantaneously to open the specific bug filter A cleaning step of the specific bag-type filter element for performing a pulse backwashing step of pulse backwashing the element, and
The powder recovery method, wherein the cleaning step is sequentially repeated for the remaining (n-1) bug type filter elements.   5. The powder recovery method according to claim 4, wherein in the cleaning step, vibration is applied to the specific bug type filter element to be cleaned.   6. The powder recovery method according to claim 4, wherein the toner for developing an electrostatic charge image is recovered.

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