JP5050439B2 - Water repellent powder production equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce in size the equipment for manufacturing, after subjecting a mixture of water-repellent powders and water to treatment, the water-repellent powders as an end product. <P>SOLUTION: In the main unit (15) of the manufacturing equipment (10), many conveying trays (70) are arranged up and down. Into each conveying tray (70) is placed the half-finished product obtained as a mixture of PTFE powders and water. In the ascent side space (26), the conveying trays (70) move upwards and in the descent side space (27), they move downward. Each conveying tray (70) passes the first drying zone (41), the second drying zone (42) and the heat treatment zone (43) in turn. In the first drying zone (41), is conducted the drying treatment utilizing microwave and in the second one (42), is performed the drying treatment utilizing hot air. In the heat treatment zone (43), the temperature of the dried PTFE powders is kept at about 160&deg;C. The half-finished product on the conveying trays (70) passes these three zones in turn to end up in the PTFE powders as the finished product. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to an apparatus for obtaining a water-repellent powder as a final product by processing a semi-finished product obtained in the process of producing a water-repellent powder.

  Conventionally, as a water-repellent powder, a powder made of a fluorine-containing resin such as polytetrafluoroethylene (hereinafter referred to as “PTFE”) is known. The powder made of this type of fluorine-containing resin may be used, for example, as a material for covering electric wires or various molded products.

  In the production process of such a water-repellent powder, a polymerization reaction in water may be performed. In such a case, the water-repellent powder is obtained as a slurry-like semi-product containing a large amount of water. become. For this reason, in order to obtain the water-repellent powder as the final product, it is necessary to dry the semi-finished product obtained as a mixture of the water-repellent powder and water.

For example, Patent Document 1 discloses that a semi-finished product is dried by irradiating the semi-finished product with microwaves. On the other hand, Patent Document 2 discloses a heating device that heats an object using microwaves. This heating device continuously heats the heating object by irradiating microwaves while moving the heating object in the horizontal direction with a roller conveyor.
JP-A-11-235720 JP 2003-100441 A

  Even when the semi-finished product obtained in the process of producing the water-repellent powder is dried, it is conceivable that the semi-finished product as disclosed in Patent Document 2 is continuously dried. However, the water repellent powder may be required to have a very low moisture content. In such a case, it takes a long time (several hours to several tens of hours) to dry the semi-finished product. For this reason, when trying to dry a certain amount of semi-finished product continuously, the path for moving the semi-finished product becomes very long, and there is a risk that the apparatus for processing the semi-finished product becomes large.

  This invention is made | formed in view of this point, The objective is to reduce in size the apparatus which processes a mixture of water-repellent powder and water, and manufactures the water-repellent powder as a final product.

  The first invention is directed to an apparatus for producing a water-repellent powder as a final product by treating a semi-finished product (80) obtained as a mixture of water-repellent powder and water in the process of producing the water-repellent powder. And a transfer tray (70) for placing the semi-finished product (80) and a passage space (25) in which the plurality of arranged transfer trays (70) move in the arrangement direction. A main body (15) that performs at least a drying process for drying the semi-finished product (80) on the transport tray (70) moving in the space (25). In the main body (15), The passage space (25) is formed so as to extend in the vertical direction, and the plurality of transfer trays (70) are arranged vertically along the extending direction of the passage space (25).

  In the first invention, the semi-finished product (80) obtained as a mixture of the water-repellent powder and water in the process of producing the water-repellent powder is placed on the transport tray (70). In the main body (15), the semi-finished product (80) on the transfer tray (70) is dried. Specifically, a passage space (25) extending in the vertical direction is formed in the main body (15). In the passage space (25), the plurality of transfer trays (70) move upward or downward while being arranged in the vertical direction. In the main body (15), a process for drying the semi-finished product (80) on the transfer tray (70) moving in the passage space (25) is performed.

  Examples of the water-repellent powder include general-purpose resin powder and so-called engineering plastic powder. Specifically, polyethylene, polyvinyl chloride, polypropylene, polystyrene, polyvinyl acetate, ABS resin (acrylonitrile-butadiene-styrene resin), AS resin (acrylonitrile-styrene resin), methacrylic resin, polyacetal, polyamide, polyimide, polyamideimide Examples of the water-repellent powder include powders such as polycarbonate, polyphenylene ether, polybutylene terephthalate, polyanilate, polysulfone, polyethersulfone, polyetherimide, polyphenylene sulfide, polyetheretherketone, and fluorine-containing resin.

  In addition, as a powder of fluororesin which is a kind of water repellent powder, polytetrafluoroethylene (PTFE), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), ethylene / tetrafluoroethylene copolymer (ETFE), ethylene / chlorotrifluoroethylene copolymer (ECTFE), etc. Illustrated.

In addition to the above configuration , the first invention irradiates the passage space (25) of the main body (15) with the microwave on the semi-finished product (80) on the transfer tray (70). The first area (41) for evaporating water contained in the semi-finished product (80) and the semi-finished product (80) on the transfer tray (70) that has passed through the first area (41) are heated with hot air. A second region (42) for evaporating water remaining in the semi-finished product (80) by heating and a semi-finished product (80) on the transfer tray (70) that has passed through the second region (42) are predetermined. A third region (43) for obtaining a water-repellent powder as a final product is formed by maintaining the temperature at a predetermined temperature over time.

In the first invention, the first region (41), the second region (42), and the third region (43) are formed in the passage space (25) of the main body (15).

In the 1st field (41) of the 1st invention, a microwave is irradiated to semi-finished product (80) on tray (70) for conveyance stored there. The water contained in the semi-finished product (80) generates heat by absorbing microwaves and evaporates. As a result, the amount of water contained in the semi-finished product (80) gradually decreases.

The transport tray (70) that has passed through the first region (41) is fed into the second region (42) of the first invention, and the semi-finished product (80) on the transport tray (70) is warm air. Heated by. From the semi-finished product (80) heated by the warm air, water remaining there evaporates. Since the semi-finished product (80) that has passed through the first region (41) has a low water content to some extent, the remaining water may be dispersed as fine droplets. On the other hand, in the second region (42), since water is evaporated by heating with warm air instead of microwaves, the water in the form of fine droplets is also heated and evaporated.

In the third area (43) of the first invention, the transfer tray (70) that has passed through the second area (42) is fed, and the semi-finished product (80) on the transfer tray (70) is returned at a predetermined time. It is kept at a predetermined temperature throughout. In this third region (43), the remaining amount of water becomes sufficiently low, and at the same time, the semi-finished product (80) that has been exposed to warm air and has risen in temperature is maintained at a predetermined temperature for a predetermined time. For example, when PTFE powder, which is a kind of water repellent powder, is exposed to a high temperature of a certain temperature for a certain period of time, the pressure (extrusion pressure) required for extrusion molding becomes almost constant at a certain value. . The step in the third region (43) is performed for the purpose of stabilizing the extrusion pressure of the water repellent powder, for example.

  According to a second invention, in the first invention, the passage space (25) includes a rising portion (26) in which the transfer tray (70) moves upward, and the transfer tray (70). And a lowering part (27) that moves downward, and the main body part (15) moves the transport tray (70) from the rising part (26) to the lowering part (27). It is comprised so that it may move in order.

  In the second invention, an ascending portion (26) and a descending portion (27) are formed in the passage space (25). In the main body (15), the transfer tray (70) moves upward in the rising portion (26) of the passage space (25), and then moves from the rising portion (26) to the falling portion (27). Move the descending part (27) downward.

According to a third invention, in the first or second invention, the transfer tray (70) is made of a metal bottom plate member (71) and a resin-made plate extending upward from the periphery of the bottom plate member (71). The main body (15) is configured to irradiate microwaves from the side of the transfer tray (70) moving in the first region (41). It is.

In the third invention, the metal bottom plate member (71) and the resin side plate member (73) are provided on the transfer tray (70). In the first region (41) of the main body (15), microwaves are irradiated from the side to the plurality of transfer trays (70) arranged vertically. Here, since the resin has a property of transmitting microwaves, the microwave irradiated from the side of the transfer tray (70) is not obstructed by the side plate member (73) and is not disturbed on the transfer tray (70). To reach semi-finished products (80). On the other hand, since metal has a property of reflecting microwaves, microwaves incident between one adjacent transport tray (70) are reflected on two bottom plate members (71) arranged vertically. Proceed and spread throughout the transfer tray (70).

In a fourth aspect based on the third aspect , in the main body (15), at least the first region forming portion (21) for forming the first region (41) is formed of a metal member. Each of the end portions located on both sides of the moving direction of the transfer tray (70) in the first region forming portion (21) is a bottom plate of the transfer tray (70) closest to the end portion. The distance from the member (71) is always less than ¼ of the wavelength of the microwave irradiated in the first region (41).

In 4th invention, the 1st area | region formation part (21) which forms the 1st area | region (41) among this exterior is comprised with a metal member. For this reason, the microwave irradiated in the 1st field (41) is reflected by the 1st field formation part (21). Further, at each end portion on both sides of the first region forming portion (21), the distance from the bottom plate member (71) of the nearest transfer tray (70) is irradiated in the first region (41). The wavelength is set to less than ¼ of the wavelength of the microwave. Generally, the microwave cannot pass through the gap when the gap between the metal members is less than ¼ of the wavelength. Therefore, the microwave irradiated in the first region (41) does not leak out from the first region (41).

According to a fifth invention, in any one of the first to fourth inventions, the main body (15) is configured to ventilate the first region (41).

In 5th invention, a main-body part (15) ventilates a 1st area | region (41). Water (water vapor) evaporated from the semi-finished product (80) in the first region (41) is discharged from the first region (41) together with the air in the first region (41). In the present invention, when the first region (41) is ventilated, all of the air flowing out from the first region (41) is exhausted, and the flow rate of the air flowing out from the first region (41) The flow rate of the outside air supplied to the region (41) may be the same, or only a part of the air flowing out from the first region (41) is exhausted, and the rest is mixed with the outside air to the first region (41). You may make it send back.

In a sixth aspect based on any one of the first to fifth aspects, the main body (15) is heated in the second region (42) while ventilating the second region (42). While the air is circulated, the temperature in the third region (43) is kept at a predetermined value without ventilating the third region (43).

In the sixth invention, the main body (15) ventilates the second region (42). The water (water vapor) evaporated from the semi-finished product (80) in the second region (42) is discharged from the second region (42) together with the air in the second region (42). In the present invention, when the second region (42) is ventilated, all of the air flowing out from the second region (42) is exhausted, and the flow rate of the air flowing out from the second region (42) and the second The flow rate of the outside air supplied to the region (42) may be the same, or only a part of the air flowing out from the second region (42) is exhausted, and the rest is mixed with the outside air to the second region (42). You may make it send back.

Moreover, in this 6th invention, a main-body part (15) maintains the air temperature in a 3rd area | region (43) at a predetermined value, without ventilating a 3rd area | region (43). In this third region (43), the semi-finished product (80) that has passed through the first region (41) and the second region (42) and the remaining amount of water has already become sufficiently low is treated. Water hardly evaporates from the semi-finished product (80) in the three regions (43). Therefore, in the main body (15) of the present invention, the third region (43) is not ventilated.

According to a seventh invention, in any one of the first to sixth inventions, the water-repellent powder is polytetrafluoroethylene powder.

In the seventh invention, dry PTFE powder as a final product is produced from a semi-finished product (80) obtained as a mixture of PTFE powder and water.

In an eighth aspect based on the first aspect , the main body (15) has the semi-finished product (80) in order to evaporate impurities contained in the semi-finished product (80) in the third region (43). ) Is maintained at a temperature higher than the boiling point of the impurity.

In the eighth aspect , in the third region (43) of the main body (15), the temperature of the semi-finished product (80) that has passed through the second region (42) is maintained for a predetermined time. It is kept higher than the boiling point of impurities inside. Here, in the manufacturing process of the water-repellent powder, an additive may be added for the purpose of, for example, promoting the particle formation reaction. In such cases, the additive often remains as an impurity in the powder. Therefore, in the main body (15) of the present invention, the semi-finished product (80) in the third region (43) is kept at a temperature higher than the boiling point of the impurities contained therein, and the impurities in the semi-finished product (80) are evaporated. Thus, it is removed from the water repellent powder.

  In the present invention, the transfer tray (70) on which the semi-finished product (80) is placed is arranged vertically in the main body (15), and a plurality of transfer trays (70) arranged vertically are moved in the vertical direction. The semi-finished product (80) on the transfer tray (70) is dried. Here, when arranging a plurality of transfer trays (70) in the horizontal direction, the floor area occupied by the arranged transfer trays (70) is equal to the bottom area of the transfer tray (70). The value is multiplied by the number. On the other hand, when arranging a plurality of transfer trays (70) in, for example, a line in the vertical direction, the floor area occupied by the arranged transfer trays (70) is only the bottom area of one transfer tray (70). is there. For this reason, if a plurality of transfer trays (70) are arranged one above the other as in the present invention, the floor area occupied by the main body (15) of the manufacturing apparatus (10) can be greatly reduced. Miniaturization can be achieved.

In the present invention , when drying the semi-finished product (80) obtained as a mixture of water-repellent powder and water, a step of drying using microwaves and a step of drying using hot air are sequentially performed. Yes.

  Here, in the mixture of powder and water, when the amount of water contained in the mixture is below a certain level, the water may not be collected in one place but may be widely dispersed in the powder. In particular, since PTFE is a highly water-repellent substance, when the water-repellent powder contains a relatively small amount of water, most of the water tends to be scattered in the water-repellent powder in the form of fine droplets. When water is dispersed as droplets that are significantly shorter than the wavelength of the microwave, the proportion of microwaves absorbed by the water becomes even lower, and the temperature of the water droplets hardly rises no matter how much microwaves are irradiated. It will fall into a state.

On the other hand, in the present invention , when the water content of the semi-finished product (80) is relatively high (that is, when water is collected in the water repellent powder to some extent), it is heated by microwaves. While the water is rapidly evaporated, the water content of the semi-finished product (80) becomes low (that is, the water is dispersed as droplets in the water-repellent powder), and the microwave heats the water efficiently. When it is no longer possible, the water is reliably evaporated by heating with warm air. Therefore, according to the present invention , the water-repellent powder can be surely dried, and at the same time, by selecting an optimal heating method according to the amount of water contained in the semi-finished product (80), the semi-finished product (80 ) Drying can be shortened.

  In the second invention, the transfer tray (70) on which the semi-finished product (80) is placed moves upward in the rising portion (26) of the passage space (25) and then turns back to return to the falling portion (27 ) Move down. Therefore, according to the present invention, the height of the main body (15) can be kept lower than when the transfer tray (70) is moved only upward or downward in the main body (15).

In the third aspect , the material of the side plate member (73) of the transfer tray (70) is a resin having a property of transmitting microwaves. For this reason, in the case of irradiating the microwave from the side of the transfer tray (70), the microwave can reach the semi-finished product (80) with almost no loss, and the irradiated microwave can be used without waste. ) Can be used for drying. Furthermore, in the present invention, the material of the bottom plate member (71) of each of the transport trays (70) arranged vertically is a metal having a property of reflecting microwaves. For this reason, when the microwave is irradiated from the side of the transfer tray (70), the microwave can be spread over the entire semi-finished product (80) on the transfer tray (70). 70) The entire upper semi-finished product (80) can be heated uniformly.

In the fourth aspect of the invention, the first region forming portion (21) is made of metal, and further, the metal bottom plate member (71) of the transfer tray (70) and both ends of the first region forming portion (21). The distance is set to be less than ¼ of the wavelength of the microwave irradiated in the first region (41). Therefore, according to the present invention, it is possible to prevent the microwave irradiated in the first region (41) from leaking to the outside, and to ensure the safety of the manufacturing apparatus (10).

In the fifth aspect of the invention, the semi-finished product (80) in the first region (41) is irradiated with microwaves while the first region (41) in which the semi-finished product (80) is accommodated is ventilated. Therefore, according to the present invention, water (water vapor) evaporated from the semi-finished product (80) in the first region (41) can be quickly discharged out of the first region (41). The time required for drying 80) can be further shortened.

In the sixth aspect of the invention, the third region (43) in which the step of maintaining the semi-finished product (80) that has been dried with warm air at a predetermined temperature is not ventilated. Therefore, according to the present invention, the energy required to keep the temperature in the third region (43) at the predetermined temperature can be reduced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment 1 of the Invention
A first embodiment of the present invention will be described.

-Manufacturing equipment-
The production apparatus (10) of the present embodiment produces a dried PTFE powder as a final product by processing the semi-finished product (80) obtained as a mixture of PTFE powder and water in the production process of PTFE powder. belongs to. Note that “right”, “left”, “front”, and “back” used in the following description all mean that the manufacturing apparatus (10) is viewed from the front side.

  As shown in FIG. 1, the main body (15) of the manufacturing apparatus (10) includes a metal main body casing (20) formed in a vertically long rectangular parallelepiped shape. The main casing (20) has a lateral width in the left-right direction that is longer than the depth. The internal space of the main casing (20) forms a passage space (25). A flat partition wall (22) is erected in the passage space (25). The passage space (25) is partitioned by the partition wall (22) into a left ascending space (26) and a right descending space (27). The ascending side space (26) constitutes a rising part of the passage space (25), and the descending side space (27) constitutes a descending part of the passage space (25). The height of the partition wall (22) is lower than the height of the passage space (25). For this reason, the upper end of the ascending space (26) and the upper end of the descending space (27) communicate with each other.

  The input side roller conveyor (51) is inserted into the lower end of the main body (15) from the left side, and the discharge side roller conveyor (52) is inserted from the right side thereof. The end of the input side roller conveyor (51) is located in the ascending space (26), and the transport tray (70) on which the semi-finished product (80) is placed is carried into the ascending space (26). . The discharge-side roller conveyor (52) has a starting end located in the descending space (27), and carries the transport tray (70) on which PTFE powder as a final product is placed from the descending space (27). To do. The structure of the transfer tray (70) will be described later.

  The main body (15) is provided with a tray drive (50) as a transport mechanism. Although not shown, the tray driving section (50) includes an arm member that extends in the horizontal direction in order to place the transfer tray (70). In the tray drive section (50), a large number of arm members are arranged at equal intervals. The tray driving section (50) transports the transport tray (70) in the passage space (25) by moving the arm member on which the transport tray (70) is placed. Specifically, the tray driving unit (50) moves the transfer tray (70) sent to the rising side space (26) upward, and reaches the upper end of the rising side space (26). ) Is moved to the lowering space (27), and the transfer tray (70) sent to the lowering space (27) is moved downward.

  As shown in FIG. 2, the ascending space (26) has a lower end portion serving as a charging zone (44) and a portion extending from the upper end of the charging zone (44) to a predetermined height as a first drying zone (41). The remaining portions located above the first drying zone (41) constitute the second drying zone (42), respectively. The lower side space (27) has a lower end portion in the discharge zone (45), a portion extending from the upper end of the discharge zone (45) to a predetermined height in the heat treatment zone (43), and the upper portion in the heat treatment zone (43). The remaining part located in each constitutes the second drying zone (42). That is, the second drying zone (42) is formed from the ascending space (26) to the descending space (27).

  The first drying zone (41) is a space for irradiating the semi-finished product (80) on the transfer tray (70) with microwaves to evaporate water in the semi-finished product (80). One area is configured. A part of the main casing (20) forming the first drying zone (41) constitutes a first zone forming part (21). A microwave generator (60) is attached to the first zone forming part (21). The microwave generator (60) generates a microwave (that is, an electromagnetic wave having a frequency of 300 MHz to 30 GHz) and radiates the generated macro wave into the first drying zone (41).

  In the main casing (20), the first air outlet (31) is opened at a portion facing the first drying zone (41) in the rear surface (that is, the rear side surface), and the front surface (that is, the front side surface). ) In the portion facing the first drying zone (41). The main body (15) is configured to ventilate the first drying zone (41). Specifically, the main body (15) heats the taken-in outside air to about 80 ° C., supplies the air from the first air outlet (31) to the first drying zone (41), and takes in the air taken into the first air inlet. All of these are discharged outdoors. The part which forms the 1st drying zone (41) among main parts (15) constitutes the 1st treating part (16).

  The second drying zone (42) is a space for performing a process of evaporating moisture in the semi-finished product (80) by applying hot air to the semi-finished product (80) on the transport tray (70). Is configured. On the back surface of the main casing (20), the second air outlet (32) is located at the portion facing the second drying zone (42) on the ascending side space (26) side, and the second drying zone (on the descending side space (27) side) The third outlets (33) are open at the part facing 42). In addition, on the front surface of the main casing (20), a second suction port is provided at a portion facing the second drying zone (42) in the ascending space (26), and the second drying zone (42 in the descending space (27). The third suction port is opened at the part facing ().

  The main body (15) is configured to ventilate the second drying zone (42). Specifically, the main body (15) discharges a part of the air taken into the second suction port and the third suction port to the outside, and mixes the remainder with the outside air to mix the second air outlet (32) and It supplies to a 2nd drying zone (42) from a 3rd blower outlet (33). At that time, the main body (15) is arranged so that the temperature of the air supplied from the second air outlet (32) and the third air outlet (33) to the second drying zone (42) is about 160 ° C. Heating. A portion of the main body (15) that forms the second drying zone (42) constitutes a second processing unit (17).

  The heat treatment zone (43) is a space for performing a process of maintaining the semi-finished product (80) on the transfer tray (70) at a predetermined temperature for a predetermined time, and constitutes a third region. In the main casing (20), the fourth outlet (34) opens in the part facing the heat treatment zone (43) on the back surface, and the fourth suction port opens in the part facing the heat treatment zone (43) on the front surface. doing.

  The main body (15) is configured to circulate air in the heat treatment zone (43) in order to average the air temperature in the heat treatment zone (43). Specifically, the main body (15) takes in the air in the heat treatment zone (43) from the fourth suction port, and sends all of the taken-in air back to the heat treatment zone (43) from the fourth outlet (34). At that time, the main body (15) appropriately heats the air supplied from the fourth outlet (34) to the heat treatment zone (43) so that the temperature in the heat treatment zone (43) is maintained at about 160 ° C. To do. The part of the main body (15) that forms the heat treatment zone (43) constitutes the third processing part (18).

  The transfer tray (70) is formed in a substantially square shape. As shown in FIGS. 3 and 4, the transfer tray (70) includes a metal bottom plate member (71) and a resin side plate member (73). The bottom plate member (71) is formed in a substantially square flat plate shape. The side plate member (73) is formed in an elongated rectangular plate shape, and is erected along the four sides of the bottom plate member (71). Examples of the material of the bottom plate member (71) include stainless steel. Moreover, as a material of the side plate member (73), for example, polytetrafluoroethylene (PTFE) is exemplified. The material of the side plate member (73) may be any material as long as it has a small loss coefficient (that is, easily transmits microwaves or hardly absorbs microwaves). Etc.

  In the transfer tray (70), the side plate member (73) is detachable from the bottom plate member (71). As shown in FIG. 5, in the bottom plate member (71), a protruding portion (72) extending along the periphery thereof is formed so as to protrude outward from the periphery. The protrusion (72) has a T-shaped cross section. A fitting groove (74) extending along the longitudinal direction is formed in the lower part of the side plate member (73). The fitting groove (74) has a T-shaped cross section corresponding to the cross sectional shape of the protrusion (72). The side plate member (73) is connected to the bottom plate member (71) by fitting the fitting groove (74) into the protrusion (72) of the bottom plate member (71).

  As shown in FIG. 3, a metal frame member (23) is provided in the first zone forming part (21) of the main casing (20). One frame-like member (23) is arranged at the entrance and exit of the first drying zone in such a posture as to surround the periphery of the transfer tray (70) moving in the first drying zone.

  The inner side surfaces of the end portions (that is, the lower and upper end portions) of the first zone forming portion (21) are formed by the inner surface of the frame-shaped member (23). . The inner side surface of each frame member (23) is a flat surface having a height of H. The height H of the inner side surface is equal to the interval H between two bottom plate members (71) adjacent to each other in the transfer tray (70) moving vertically in the first drying zone. . This interval H is set to 1/4 or more of the wavelength λ of the microwave radiated from the microwave generator (60) (that is, λ / 4). For example, when the frequency of the microwave generated by the microwave generator (60) is 2.5 GHz, since the wavelength λ of the microwave is 120 mm, the distance H is set to 30 mm or more.

  In a state where the transfer tray (70) is positioned on the side of the frame-shaped member (23), the distance L between the bottom plate member (71) of the transfer tray (70) and the inner surface of the frame-shaped member (23) is The wavelength is set to less than ¼ (that is, λ / 4) of the wavelength λ of the microwave radiated from the microwave generator (60). That is, in the above example (when λ = 120 mm), the distance L is set to be less than 30 mm. As described above, the height of the inner surface of the frame-like member (23) is equal to the interval between the bottom plate members (71) of the adjacent transfer trays (70). Therefore, the distance between the inner surface of the frame-like member (23) and the bottom plate member (71) of the transfer tray (70) closest to the frame-like member (23) is the same as the position of the transfer tray (70). Will always be the distance L regardless of.

-Driving action-
The operation of the manufacturing apparatus (10) will be described with reference to FIGS. In this manufacturing apparatus (10), the process for obtaining the PTFE powder as a final product from the semi-finished product (80) obtained as a mixture of PTFE powder and water is performed.

  The semi-finished product (80) obtained as a mixture of PTFE powder and water in the previous step of the processing by the manufacturing apparatus (10) is placed on the transfer tray (70). In the transfer tray (70), the thickness of the layer of the semi-finished product (80) placed thereon is substantially uniform. The semi-finished product (80) in this state has a moisture content of almost 100%. That is, in this semi-finished product (80), 100 parts by mass of water is mixed with 100 parts by mass of PTFE powder.

  The transfer tray (70) on which the semi-finished product (80) having a moisture content of 100% is carried is carried by the loading side roller conveyor (51) and carried into the charging zone (44) of the main body (15). In the semi-finished product (80) placed on the transfer tray (70) in the charging zone (44), the gap between the PTFE particles (81) is completely filled with water as shown in FIG. 6 (a). It has become. The transfer tray (70) carried into the input zone (44) is carried by the tray drive unit (50), moves upward in the ascending space (26) of the passage space (25), and moves to the first drying zone ( 41). The tray drive unit (50) moves the transfer tray (70) at a slow speed of, for example, about 2 cm per minute.

  In the first drying zone (41), the first drying process for the semi-finished product (80) on the transfer tray (70) is performed as a drying process. Specifically, in the first drying zone (41), the carried transport tray (70) slowly moves upward, and enters the semi-finished product (80) on the moving transport tray (70). Microwave is irradiated. The water contained in the semi-finished product (80) rises in temperature by absorbing microwaves and evaporates. Water (ie, water vapor) evaporated from the semi-finished product (80) is discharged to the outdoors together with the air in the first drying zone (41).

  As a result, in the semi-finished product (80) on the transfer tray (70) moving in the first drying zone (41), the amount of water contained therein gradually decreases as shown in FIGS. go.

  Specifically, in the initial stage of the first drying step, the gap between the PTFE particles (81) is almost completely filled with water (see FIG. 6B), or the gap between the PTFE particles (81). The water is present in a large lump (see FIG. 6C). In this state, almost all of the microwave energy absorbed by the semi-finished product (80) on the transfer tray (70) is consumed to evaporate water. That is, the initial stage of the first drying step is a so-called constant rate drying period (or constant rate drying period).

  On the other hand, from the middle to the end of the first drying process, in the semi-finished product (80), a relatively large lump of water and relatively small droplets of water are mixed (FIG. 6 (d)). See). In this state, a part of the microwave energy absorbed by the semi-finished product (80) on the transfer tray (70) is expended to raise the temperature of the PTFE particles (81), and the rest is water. Is spent to evaporate. That is, the middle and final stages of the first drying process are periods in which both so-called constant rate drying and reduced rate drying are performed.

  In the first drying zone (41), the semi-finished product (80) on the transfer tray (70) is irradiated with microwaves, and at the same time, hot air of about 80 ° C. circulates inside. In the semi-finished product (80) on the transport tray (70), the PTFE particles (81) located near the surface thereof are heated by hot air, and the temperature of the PTFE particles (81) rises relatively quickly. For this reason, the water evaporated from the semi-finished product (80) is discharged into the air without condensing even if it comes into contact with the PTFE particles (81), and is discharged together with the air from the first drying zone (41).

  In the semi-finished product (80) on the transfer tray (70) that has reached the outlet of the first drying zone (41), the moisture content is reduced to about 20%. Moreover, in this semi-finished product (80), the temperature (powder temperature) of PTFE powder has risen to about 80 ° C. The transfer tray (70) on which the semi-finished product (80) having a moisture content of about 20% is carried is transported from the first drying zone (41) to the second drying zone (42).

  In the second drying zone (42), the second drying process for the semi-finished product (80) on the transfer tray (70) is performed as a drying process. Specifically, in the second drying zone (42) in the ascending space (26), the carried transport tray (70) slowly moves upward. On the other hand, in the second drying zone (42) in the descending space (27), the carried transport tray (70) slowly moves downward. In the second drying zone (42), hot air of about 160 ° C. is blown onto the semi-finished product (80) on the moving transfer tray (70). The water contained in the semi-finished product (80) is heated by hot air to evaporate. Water (that is, water vapor) evaporated from the semi-finished product (80) is discharged outdoors together with the air in the second drying zone (42). Here, the temperature of the hot air flowing through the second drying zone (42) is about 160 ° C., but the temperature of the hot air should be higher than the evaporation temperature of water under atmospheric pressure (ie, 100 ° C.). That's fine.

  As a result, in the semi-finished product (80) on the transport tray (70) moving in the second drying zone (42), the amount of water contained therein gradually decreases as shown in FIGS. go.

  Specifically, at the start of the second drying step, the water remaining in the semi-finished product (80) becomes fine droplets and is dispersed in the PTFE powder (see FIG. 6 (e)). Yes. Since PTFE is a water-repellent substance, even if the moisture content of the semi-finished product (80) is not so low (for example, the moisture content is about 20%), the water remaining in the semi-finished product (80) is liquid. Drop and disperse. In this state, a part of the heat applied from the hot air to the semi-finished product (80) is consumed for evaporating the water, and the rest is consumed for increasing the temperature of the PTFE particles (81). That is, the second drying process is a so-called reduced rate drying period.

  In the semi-finished product (80) on the transfer tray (70) that has reached the outlet of the second drying zone (42), the water content is reduced to 0.01% or less. Further, in this semi-finished product (80), the temperature of the PTFE powder is increased to about 155 ° C. The transfer tray (70) on which the semi-finished product (80) having a moisture content of approximately 0% is loaded is transported from the second drying zone (42) to the heat treatment zone (43).

  In the heat treatment zone (43), a heat treatment process for the semi-finished product (80) on the transfer tray (70) is performed. Specifically, the temperature of the heat treatment zone (43) is maintained at about 160 ° C. In the heat treatment zone (43), the carried transport tray (70) slowly moves downward, and the semi-finished product (80) on the transport tray (70) (that is, the moisture content becomes almost 0%). PTFE powder) is exposed to an atmosphere of about 160 ° C. The transfer tray (70) that has moved to the heat treatment zone (43) reaches the outlet of the heat treatment zone (43) in about 30 minutes. That is, in the heat treatment zone (43), as shown in FIG. 7, the temperature of the PTFE powder on the transfer tray (70) is maintained at about 155 ° C. for about 30 minutes.

  When the temperature of the PTFE powder having a water content of almost 0% is kept at a certain high temperature, the extrusion pressure (pressure required for extruding the PTFE powder) gradually increases at first, and for a certain period of time. When elapses, the extrusion pressure does not increase any more and remains substantially constant. Therefore, in the heat treatment step performed in the heat treatment zone (43), the temperature of the PTFE powder is maintained at about 155 ° C. over a time required for the PTFE powder to have a constant extrusion pressure. By performing this heat treatment step, the extrusion pressure of the PTFE powder as the final product becomes a value within a range of ± about 7% with respect to the reference value.

  PTFE powder as a final product is placed on the transfer tray (70) reaching the lower end of the heat treatment zone (43). The transport tray (70) on which the PTFE powder as the final product is placed is lowered to the start end of the discharge roller conveyor (52) and carried out of the main body (15).

-Effect of Embodiment 1-
In the manufacturing apparatus (10) of this embodiment, when drying the semi-finished product (80) obtained as a mixture of PTFE powder and water, a first drying process using microwaves and a second drying process using hot air are performed. It goes in order.

  Here, in the mixture of powder and water, when the water content of the mixture is below a certain level, the water is not concentrated in one place but is widely dispersed in the powder. In particular, since PTFE is a highly water-repellent substance, when the PTFE powder contains a relatively small amount of water, most of the water is scattered in the PTFE powder in the form of fine droplets. For this reason, in the semi-finished product (80) in which the water content is reduced to about 20%, as shown in FIG. 6 (e), the water is in a state of being dispersed in the PTFE powder as fine droplets. It is estimated to be.

  On the other hand, when using microwaves to dry an object, it is known that the proportion of the microwave absorbed by water decreases as the moisture content of the object decreases. In particular, in a mixture of PTFE powder having water repellency and water, water easily contacts the PTFE particles (81) to form droplets. For this reason, even if the moisture content is not so low, the water contained in the semi-finished product (80) is dispersed as fine droplets. When water is dispersed as droplets that are significantly shorter than the wavelength of the microwave, the proportion of microwaves absorbed by the water becomes even lower, and the temperature of the water droplets hardly rises no matter how much microwaves are irradiated. It will fall into a state.

  Therefore, in the production apparatus (10) of the present embodiment, when the moisture content of the semi-finished product (80) is relatively high (that is, when water is collected to some extent in the PTFE powder), the microwave is used. While the water is rapidly evaporated by heating, the water content of the semi-finished product (80) is lowered (that is, the water is dispersed as droplets in the PTFE powder). When heating is no longer possible, water is reliably evaporated by heating with hot air. Therefore, according to this embodiment, the moisture content of the PTFE powder as the final product can be reduced to almost 0%, and at the same time, an optimum heating method is selected according to the moisture content of the semi-finished product (80). As a result, the drying of the semi-finished product (80), which conventionally required ten or more hours, can be completed in about two to three hours.

  For reference, when drying the semi-finished product (80), the duration of the drying process (when using microwaves and hot air, using only hot air, and using only microwaves) The relationship between the drying time) and the water content of the semi-finished product (80) is shown in FIG. When the semi-finished product (80) is heated only with hot air, the moisture content of the semi-finished product (80) decreases only slowly as shown by the square marks in the figure, and the drying time must be extremely long. The water content of the semi-finished product (80) cannot be reduced to almost 0%. In addition, when the semi-finished product (80) is heated only by microwave irradiation, the moisture content of the semi-finished product (80) rapidly increases immediately after the microwave irradiation is started, as plotted by the circles in the figure. However, when a certain amount of time elapses, the rate at which the moisture content decreases decreases and the moisture content does not decrease below 20%. On the other hand, when the semi-finished product (80) is heated by using both microwave irradiation and hot air supply as in this embodiment, the water content of the semi-finished product (80) is drastically reduced. At about 70 minutes after the start of drying, the water content of the semi-finished product (80) reaches approximately 0%.

  By the way, since PTFE powder hardly absorbs microwaves, the temperature rise of PTFE powder due to microwave irradiation can hardly be expected. This is as described above. Therefore, when microwaves are applied to a semi-finished product (80) having the same temperature as the ambient temperature of the manufacturing apparatus (10) (for example, around 20 ° C.), the temperature of the water in the semi-finished product (80) rises quickly, The temperature of the PTFE powder in the product (80) increases only gradually. In this state, the remaining amount of water in the mixture often does not decrease easily. This is presumed to be because most of the heated and evaporated water comes into contact with the low-temperature water-repellent powder and condenses.

  In contrast, the manufacturing apparatus (10) of the present embodiment irradiates the semi-finished product (80) on the transfer tray (70) with microwaves in the first drying zone (41) and at the same time close to the boiling point of water. Hot air at a temperature (for example, about 80 ° C. to 100 ° C.) is circulated. As a result, in the semi-finished product (80) on the transport tray (70), the PTFE particles (81) located near the surface are heated by the hot air, and the temperature of the PTFE particles (81) rises relatively quickly. . For this reason, the water evaporated from the semi-finished product (80) is discharged into the air without condensing even if it comes into contact with the PTFE particles (81), and is discharged from the first drying zone (41) together with the air. Become. Therefore, according to the present embodiment, it is possible to greatly reduce the amount of the evaporated water that comes into contact with the PTFE particles (81) and condense, and to rapidly reduce the remaining amount of water in the mixture.

  In this embodiment, the heat treatment step is performed in order to set the extrusion pressure of the final product PTFE powder within a predetermined target range. In the second drying step performed immediately before the heat treatment step, the semi-finished product ( 80) is heated with hot air. When the semi-finished product (80) is heated with hot air, not only the temperature of the water remaining in the semi-finished product (80) but also the temperature of the PTFE powder increases. In this embodiment, since the hot air supplied to the second drying zone (42) is set to the same temperature as the hot air supplied to the heat treatment zone (43), the temperature of the PTFE powder at the start of the heat treatment step is The temperature required for the heat treatment has already been reached. Therefore, according to this embodiment, the time required for the heat treatment step can be shortened, and the time required for obtaining the PTFE powder as the final product from the semi-finished product (80) can be shortened.

  Further, in the manufacturing apparatus (10) of the present embodiment, the transfer tray (70) on which the semi-finished product (80) is placed is arranged vertically in the main body (15), and a plurality of transfer trays (70) arranged vertically. ) Is moved vertically, so that the semi-finished product (80) on each transport tray (70) is dried. Here, when arranging a plurality of transfer trays (70) in the horizontal direction, the floor area occupied by the arranged transfer trays (70) is equal to the bottom area of the transfer tray (70). The value is multiplied by the number. On the other hand, when a plurality of transfer trays (70) are arranged in two rows in the vertical direction as in this embodiment, the floor area occupied by the arranged transfer trays (70) is the same as that of the transfer tray (70). Only twice the bottom area. For this reason, if a plurality of transfer trays (70) are arranged vertically as in this embodiment, the floor area occupied by the main body (15) of the manufacturing apparatus (10) can be greatly reduced, and the manufacturing apparatus (10) Can be miniaturized.

  Further, in the manufacturing apparatus (10) of the present embodiment, the passage space (25) in the main body (15) is divided into an ascending space (26) and a descending space (27), and the ascending space (26). Then, the transfer tray (70) is moved upward, and the transfer tray (70) is moved downward in the descending space (27). That is, the transfer tray (70) moves upward in the ascending space (26) of the passage space (25), then turns back and moves downward in the descending space (27). Therefore, according to the present embodiment, the height of the main body (15) can be kept lower than when the transfer tray (70) is moved only upward or downward in the main body (15). .

  In the present embodiment, the temperature of the first drying zone (41) is kept at about 80 ° C., and at the same time, the first drying zone (41) is ventilated. Therefore, according to the present embodiment, the relative humidity in the first drying zone (41) can be kept low to promote the evaporation of water from the semi-finished product (80). Since it can discharge | emit rapidly from a 1st drying zone (41), the time which a 1st drying process requires can be shortened.

  Moreover, in the manufacturing apparatus (10) of this embodiment, the moisture content of the PTFE powder as the semi-finished product (80) can be reduced to almost 0% by performing the first drying step and the second drying step. There is no need to ventilate the heat treatment zone (43) where the heat treatment step is performed. For this reason, the amount of heat required to keep the temperature of the heat treatment zone (43) at a predetermined value can be reduced, and the energy required for producing PTFE powder can be reduced.

  Further, in the manufacturing apparatus (10) of the present embodiment, the bottom plate member (71) of the transfer tray (70) arranged vertically in the passage space (25) of the main body (15) is made of metal and arranged vertically. The microwave is radiated from the microwave generator (60) provided on the side of the transport tray (70) to the transport tray (70). In general, metal has a property of reflecting microwaves. Therefore, the microwaves irradiated from the side of the transfer tray (70) are reflected by the upper surface of the lower bottom plate member (71) and the lower surface of the upper bottom plate member (71) as shown in FIG. While reaching the part far from the microwave generator (60). Therefore, according to the present embodiment, the semi-finished product (80) on the transfer tray (70) in the first drying zone (41) can be heated by microwaves on the whole.

In the manufacturing apparatus (10) of the present embodiment, the material of the side plate member (73) of the transfer tray (70) is a resin having a property of transmitting microwaves. For this reason, the microwave irradiated from the microwave generator (60) provided on the side of the transport trays (70) arranged vertically passes through the side plate member (73) and is almost completely lost. 80) will be reached. Therefore, according to the present embodiment, the microwave irradiated from the microwave generator (60) can be used for drying the semi-finished product (80) without waste.
Can be heated.

  In the manufacturing apparatus (10) of the present embodiment, a metal frame member (23) is provided at each of the lower end and the upper end of the first drying zone (41), and the inner surface of the frame member (23) is conveyed. The distance L between the tray (70) and the bottom plate member (71) is less than ¼ (that is, λ / 4) of the wavelength λ of the microwave irradiated from the microwave generator (60). Here, when the gap between the metal members is less than ¼ of the wavelength of the electromagnetic wave, the electromagnetic wave including the microwave cannot pass through the gap. Furthermore, in the manufacturing apparatus (10) of this embodiment, the main body casing (20) is made of metal. For this reason, according to this embodiment, the leakage of the microwave from a 1st drying zone (41) can be prevented, and the safety | security of a manufacturing apparatus (10) can be ensured.

  In addition, in the manufacturing apparatus (10) of the present embodiment, the second product (80) on the semi-finished product (80) on each transport tray (70) is moved while moving a large number of transport trays (70) arranged vertically. The first drying process, the second drying process, and the heat treatment process are sequentially performed. Therefore, even if the semi-finished product (80) obtained in the production process of PTFE powder is divided into a plurality of transfer trays (70) and processed, the semi-finished products on all the transfer trays (70) The processing conditions for (80) (for example, the temperature and flow rate of hot air hitting the semi-finished product (80)) can be made the same. For this reason, the characteristics (specifically, moisture content and extrusion pressure) of the PTFE powder on the transfer tray (70) carried out from the main body (15) can be made uniform, and stable quality PTFE powder can be obtained. it can.

<< Embodiment 2 of the Invention >>
A second embodiment of the present invention will be described. In this embodiment, a preheating zone (46) is formed in the main body (15) of the manufacturing apparatus (10) of the first embodiment, and a preheating step of heating the semi-finished product (80) in the preheating zone (46) is performed. It is what I did. Here, the configuration and operation of the manufacturing apparatus (10) of the present embodiment will be described with respect to differences from the first embodiment.

-Manufacturing equipment-
As shown in FIG. 9, in the manufacturing apparatus (10) of this embodiment, a part of the ascending space (26) of the main body (15) constitutes a preheating zone (46). Specifically, the ascending side space (26) has a lower end portion in the charging zone (44), a portion extending from the upper end of the charging zone (44) to a predetermined height in the preheating zone (46), and the preheating zone (46). ) From the upper end to a predetermined height constitutes the first drying zone (41), and the remaining part located above the first drying zone (41) constitutes the second drying zone (42).

  The preheating zone (46) is a space for heating the semi-finished product (80) on the transfer tray (70) to raise its temperature, and constitutes a preheating space or a housing space. In the main casing (20), a preheating outlet (35) is opened at a portion facing the preheating zone (46) in the rear surface (that is, the side surface on the back side), and the front surface (that is, the side surface on the front side) is opened. Of these, the preheating inlet is open at the part facing the preheating zone (46).

  The main body (15) is configured to circulate air in the preheating zone (46) in order to heat the semi-finished product (80) accommodated in the preheating zone (46). Specifically, the main body (15) takes in the air in the heat treatment zone (43) from the preheating inlet, and sends all of the taken-in air back from the preheating outlet (35) to the preheating zone (46). At that time, the main body (15) heats the air taken in from the preheating inlet to, for example, about 80 ° C., and supplies the heated air from the preheating outlet (35) to the preheating zone (46). The part which forms the preheating zone (46) in the main body (15) constitutes the preheating part (19).

-Driving action-
The operation of the manufacturing apparatus (10) of this embodiment will be described.

  In the manufacturing apparatus (10), the transfer tray (70) carried into the charging zone (44) is transferred to the preheating zone (46) by the tray driving unit (50). At this time, the temperature of the semi-finished product (80) on the transfer tray (70) is substantially the same as the ambient temperature (for example, around 20 ° C.) of the manufacturing apparatus (10).

  In the preheating zone (46), a preheating process for the semi-finished product (80) (that is, wet powder) on the transfer tray (70) is performed. Specifically, in the preheating zone (46), the carried tray (70) is slowly moved upward, and the semi-finished product (80) on the moving conveyance tray (70) is moved to the preheating zone. (46) Exposed to hot air circulating inside. The semi-finished product (80) is heated by hot air, and the temperature of the PTFE particles (81) and water contained therein increases. When the transfer tray (70) reaches the outlet of the preheating zone (46), the temperature of the PTFE particles (81) and water contained in the semi-finished product (80) is the same as that of the transfer tray (70). ) Is significantly higher than the point in time when it is carried into (for example, about 60 ° C. to 70 ° C.). The conveyance tray (70) on which the semi-finished product (80) heated in the preheating zone (46) is placed is carried from the preheating zone (46) to the first drying zone (41).

  In the first drying zone (41), microwaves are applied to the semi-finished product (80) on the transport tray (70) that has been carried in. The first drying step performed in the first drying zone (41) is the same as that in the manufacturing apparatus (10) shown in FIG. In other words, the water contained in the semi-finished product (80) absorbs microwaves, rises in temperature, evaporates and is released into the air.

-Effect of Embodiment 2-
As described above, when the semi-finished product (80) in which the temperature of the PTFE particles (81) is not high is irradiated with the microwave, the water contained in the semi-finished product (80) absorbs the microwave and temporarily It is presumed that a phenomenon occurs in which it evaporates but condenses by contact with the low temperature PTFE particles (81) and returns to the liquid again.

  On the other hand, the semi-finished product (80) on the transfer tray (70) that has been transferred to the first drying zone (41) in this embodiment is heated in the preheating zone (46) and is in a relatively high temperature state. ing. For this reason, in the 1st drying zone (41) of this embodiment, since microwave is irradiated to the semi-finished product (80) whose temperature is already comparatively high, the water in a semi-finished product (80) radiates | emits a microwave. It absorbs and evaporates all at once, and even if it contacts with PTFE particles (81), it is released into the air without condensing. Therefore, according to the present embodiment, the amount of the evaporated water that contacts with the PTFE particles (81) and condenses can be greatly reduced, and the time required for the first drying process in the first drying zone (41) can be reduced. Can be shortened.

<< Other Embodiments >>
For the manufacturing apparatus (10) of each of the above embodiments, the following modifications can be considered.

-First modification-
In the manufacturing apparatus (10), the main body (15) may be provided with a plurality of microwave generators (60).

  For example, as shown in FIG. 10, a plurality of microwave generators (60) may be arranged in a vertical line along the side wall of the first zone forming section (21). Moreover, as shown in FIG. 11, you may arrange | position a several microwave generator (60) in the upper corner part of a 1st drying zone (41).

-Second modification-
In the manufacturing apparatus (10), a member for diffusing the generated microwaves may be provided on the front surface of the microwave generator (60).

  For example, as shown in FIG. 12, a punching metal (61) is provided on the front surface of the microwave generator (60), and the microwave irradiated from the microwave generator (60) is diffused by the punching metal (61). It may be.

  Moreover, as shown in FIG. 13, a plurality of metal flaps (62) are arranged on the front surface of the microwave generator (60), and the angle of each flap (62) is adjusted to thereby adjust the microwave generator (60). You may make it diffuse the microwave irradiated from.

  Further, as shown in FIG. 14, a stirrer (63) made of a metal propeller is installed on the front surface of the microwave generator (60), and the stirrer that rotates the microwave irradiated from the microwave generator (60). You may make it diffuse by (63).

-Third modification-
In the manufacturing apparatus (10), the entire main casing (20) is made of metal, but only the first zone forming part (21) of the main casing (20) may be made of metal, and the remaining part may be made of a material other than metal. .

-Fourth modification-
In the manufacturing apparatus (10), the transfer tray (70) is continuously moved at a slow speed (for example, about 2 cm per minute), but the transfer tray (70) is intermittently moved at predetermined time intervals. You may make it move to. In this case, the transfer tray (70) is moved by 10 cm every 5 minutes, for example. In other words, in this example, the transfer tray (70) is moved by 10 cm and then held in that position, and when five minutes have passed since the transfer tray (70) started immediately before the transfer tray (70), 70) will be advanced 10 cm further.

-5th modification-
In the manufacturing apparatus (10) of each of the above embodiments, PTFE, which is a kind of fluorine-containing resin, is symmetric, but these objects are not limited to PTFE. For example, tetrafluoroethylene / hexafluoropropylene copolymer (FEP), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), ethylene / In order to produce powders such as tetrafluoroethylene copolymer (ETFE) and ethylene / chlorotrifluoroethylene copolymer (ECTFE), the production apparatus (10) and production method of this embodiment may be used.

  Further, the powder produced by the production apparatus (10) and production method of the present embodiment may be a powder made of a substance having water repellency (that is, a water-repellent powder), and is limited to a powder made of a fluorine-containing resin. Not. Here, it is generally known that a water repellency index is a contact angle of a water droplet on a solid surface. When the contact angle of water droplets on the surface of a solid made of a certain substance is 90 ° or more, it is generally said that the substance has water repellency.

  Examples of such water-repellent powders include general-purpose resin powders and so-called engineering plastic powders. Specifically, polyethylene, polyvinyl chloride, polypropylene, polystyrene, polyvinyl acetate, ABS resin (acrylonitrile-butadiene-styrene resin), AS resin (acrylonitrile-styrene resin), methacrylic resin, polyacetal, polyamide, polyimide, polyamideimide Examples of the water-repellent powder include powders such as polycarbonate, polyphenylene ether, polybutylene terephthalate, polyanilate, polysulfone, polyethersulfone, polyetherimide, polyphenylene sulfide, polyetheretherketone, and fluorine-containing resin.

-Sixth Modification-
In the 3rd process part (18) of the manufacturing apparatus (10) of this embodiment, you may perform the process (impurity removal process) of evaporating and removing the impurity which remains in a semi-finished product (80). That is, in the manufacturing method of this embodiment, this impurity removal step may be performed as the third step.

  Here, in the production process of PTFE powder, for example, a fluorine-containing emulsifier such as ammonium perfluorooctanoate may be added for the purpose of accelerating the formation reaction of the PTFE particles (81). When such an additive is added, the additive may remain as an impurity in the semi-finished product (80). Therefore, in the impurity removal step of this modification, the semi-finished product (80) is kept at a temperature higher than the boiling point and sublimation point of the impurities contained therein. For example, when the additive is ammonium perfluorooctanoate, the sublimation point is about 120 ° C., so that the temperature of the semi-finished product (80) is kept higher than 120 ° C. Thus, when the temperature of the semi-finished product (80) is kept higher than the boiling point of the impurities, the impurities in the semi-finished product (80) are evaporated and removed from the PTFE powder.

  In the impurity removal step of this modification, it is desirable to discharge the evaporated impurities from the third processing unit (18). Therefore, in the third processing unit (18) of the present modification, it is desirable to circulate hot air having a temperature higher than the boiling point of impurities in the space while ventilating the space in which the semi-finished product (80) is accommodated.

  As plotted with white triangles in FIG. 15, the moisture content of the semi-finished product (80) decreases sharply until the transport tray (70) reaches the third processing section (18). As a result, when the transfer tray (70) is carried into the third processing section (18), it is almost 0%. On the other hand, the residual amount of additive in the semi-finished product (80) was when the transport tray (70) passed the middle of the second processing section (17), as plotted with black triangles in the figure. From this point, it begins to decrease, and finally reaches a few ppm when the transfer tray (70) reaches the outlet of the third processing section (18). That is, since the temperature of the PTFE particles (81) is significantly lower than the boiling point of the additive until the transfer tray (70) reaches the middle of the second processing section (17), the additive is PTFE particles (81). Hardly evaporates. Then, when the transfer tray (70) reaches the third processing section (18), the temperature of the PTFE particles (81) becomes higher than the boiling point of the additive, and the additive actively flows from the PTFE particles (81). It will evaporate.

  When the semi-finished product (80) is kept at about 160 ° C. for a certain period of time in the third processing section (18) of this modification, impurities are evaporated from the PTFE powder and at the same time, the extrusion of the PTFE powder. The pressure stabilizes. In other words, in the third processing section (18) in this case, the impurity removal step for evaporating the impurities from the PTFE powder and the heat treatment step for stabilizing the extrusion pressure of the PTFE powder are performed simultaneously in parallel. Become.

  In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or its use.

  As described above, the present invention is useful in a process for obtaining a water-repellent powder as a final product by drying a mixture of water-repellent powder such as PTFE powder and water.

It is the schematic which shows the whole structure of the manufacturing apparatus in Embodiment 1, Comprising: (A) is the top view which looked at the manufacturing apparatus from upper direction, (B) is the front view which looked at the manufacturing apparatus from the front. It is a front view which shows schematic structure of the manufacturing apparatus in Embodiment 1. FIG. It is a front view which shows schematic structure of the principal part of the manufacturing apparatus in Embodiment 1. FIG. 3 is a cross-sectional view illustrating a schematic configuration of a transfer tray according to Embodiment 1. FIG. FIG. 3 is an enlarged cross-sectional view illustrating a main part of the transfer tray according to the first embodiment. It is a schematic diagram of the state change of the semi-finished product in a manufacturing apparatus. It is a graph which shows the time-dependent change of the state of the semi-finished product in a manufacturing apparatus. The drying time and moisture content of the semi-finished product when heating the semi-finished product using both microwave and hot air, when heating the semi-finished product with only hot air, and when heating the semi-finished product with only the microwave It is a graph which shows a relationship. It is a front view which shows schematic structure of the manufacturing apparatus in Embodiment 2. It is a front view which shows the principal part of the manufacturing apparatus in the 1st modification of other embodiment. It is a front view which shows the principal part of the manufacturing apparatus in the 1st modification of other embodiment. It is a front view which shows the principal part of the manufacturing apparatus in the 2nd modification of other embodiment. It is a front view which shows the principal part of the manufacturing apparatus in the 2nd modification of other embodiment. It is a front view which shows the principal part of the manufacturing apparatus in the 2nd modification of other embodiment. It is a graph which shows the relationship between the moisture content of a semi-finished product, the residual amount of an additive, and drying time.

10 Production equipment
15 Main unit
21 First region forming part
25 Aisle space
26 Ascending space (ascending part)
27 Lowering space (lowering part)
41 First drying zone (first zone)
42 Second drying zone (second zone)
43 Heat treatment zone (3rd area)
70 Transport tray
71 Bottom plate member
73 Side plate member
80 Semi-finished products

Claims (8)

An apparatus for producing a water-repellent powder as a final product by treating a semi-finished product (80) obtained as a mixture of the water-repellent powder and water in the process of producing the water-repellent powder,
A transfer tray (70) for placing the semi-finished product (80);
A semi-finished product on the transport tray (70) that forms a passage space (25) in which the plurality of transport trays (70) arranged in the array move in the direction of the passage, and moves in the passage space (25). A main body (15) for performing at least a drying process for drying (80),
In the main body (15), the passage space (25) is formed so as to extend in the vertical direction, and the plurality of transfer trays (70) are vertically moved along the extending direction of the passage space (25). Arranged ,
In the passage space (25) of the main body (15),
A first region (41) for evaporating water contained in the semi-finished product (80) by irradiating the semi-finished product (80) on the transfer tray (70) with microwaves;
A second region (42) for evaporating water remaining in the semi-finished product (80) by heating the semi-finished product (80) on the transfer tray (70) that has passed through the first region (41) with warm air. When,
A third region (43) for obtaining a water-repellent powder as a final product by keeping the semi-finished product (80) on the transfer tray (70) that has passed through the second region (42) at a predetermined temperature for a predetermined time. An apparatus for producing a water-repellent powder, wherein In claim 1,
The passage space (25) includes a rising portion (26) in which the transfer tray (70) moves upward, and a falling portion (27) in which the transfer tray (70) moves downward. Is formed,
The main body (15) is configured to move the transport trays (70) in order from the rising portion (26) to the falling portion (27). apparatus. In claim 1 or 2 ,
The transfer tray (70) includes a metal bottom plate member (71) and a resin side plate member (73) extending upward from the periphery of the bottom plate member (71),
The main body (15) is configured to irradiate microwaves from the side of the transfer tray (70) moving in the first region (41). apparatus. In claim 3 ,
In the main body (15), the first region forming part (21) that forms at least the first region (41) is constituted by a metal member,
Of the first region forming portion (21), each of the end portions located on both sides in the moving direction of the transfer tray (70) is a bottom plate member of the transfer tray (70) closest to the end portion. (71) The water-repellent powder manufacturing apparatus, characterized in that the distance to (71) is always less than ¼ of the wavelength of the microwave irradiated in the first region (41). In any one of Claims 1 thru | or 4 ,
The apparatus for producing water-repellent powder, wherein the main body (15) is configured to ventilate the first region (41). In any one of Claims 1 thru | or 5 ,
The main body (15) circulates warm air in the second region (42) while ventilating the second region (42), and the third region (43) without venting the third region (43). An apparatus for producing a water-repellent powder, characterized in that the temperature in the region (43) is maintained at a predetermined value. In any one of Claims 1 thru | or 6 ,
An apparatus for producing a water-repellent powder, wherein the water-repellent powder is a polytetrafluoroethylene powder. In claim 1 ,
The main body (15) keeps the temperature of the semi-finished product (80) higher than the boiling point of the impurities to evaporate impurities contained in the semi-finished product (80) in the third region (43). An apparatus for producing a water-repellent powder, characterized in that it is configured as described above.

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