JP2012025153A - Multi-stage thermoplastic resin extrusion apparatus, and method of extruding thermoplastic resin using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-stage thermoplastic resin extrusion apparatus, which is capable of producing recycled resin having higher quality, by substantially perfectly removing volatile components included in the recycled resin.SOLUTION: In the multi-stage thermoplastic resin extrusion apparatus A including a first thermoplastic resin extrusion machine 10 and a second thermoplastic resin extrusion machine 60 into which molten resin extruded from an extrusion port of the first thermoplastic resin extrusion machine flows, a resin extrusion port 50 of the first thermoplastic resin extrusion machine 10 and a resin intake port 71 of the second thermoplastic resin extrusion machine 10 are connected by a connection 100 allowing the molten resin to pass therethrough without being brought into contact with ambient air, and a depressurization chamber 120 is formed in at least part of the connection 100.

Description

  The present invention relates to a multistage thermoplastic resin extrusion apparatus and a thermoplastic resin extrusion method using the same, and more specifically, when a pulverized thermoplastic resin is pelletized or formed into a sheet for reuse. The present invention relates to a suitably used multistage thermoplastic resin extrusion apparatus and a thermoplastic resin extrusion method using the same.

  In recent years, from the viewpoint of effective use of resources and protection of the natural environment, it is a thermoplastic resin foam such as polyethylene foam or polystyrene once used as a packaging material or container, or an end material after punching a container, etc. A virgin thermoplastic resin foam is again pelletized or sheeted and reused as a raw material for resin molded products.

  For pelletization or sheet formation, an extruder having a cylinder equipped with an extrusion screw is generally used. The used or virgin thermoplastic resin foam is pulverized to an appropriate size, and then the pulverized product is supplied as a raw material into the hopper of the extruder. The supplied pulverized raw material melts while being heated and compressed in the course of feeding by rotation of the screw in the cylinder. In the process, the gas component (outside air) remaining in the foam, which is a pulverized raw material, is extracted from the vent port formed in the cylinder, and the molten resin consisting only of the resin component is extruded from the extrusion port of the cylinder. The extruded molten resin is formed into a sheet after cooling, or cut into pellets.

  In order to obtain a high-quality recycled resin pellet or recycled resin sheet, it is necessary to extrude gas components remaining in the pulverized raw material at a high rate and to extrude more quantitatively. Describes an arrangement in which two extruders are arranged in series. In addition, the extrusion apparatus of the form described in Patent Document 1 or Patent Document 2 is used not only for re-pelletization or sheet formation of a foamed resin pulverized product, but also for re-pelletization or sheeting of a non-foamed resin pulverized product. It is done.

JP-A-6-91727 JP-A-6-170920

  As described above, in order to reuse resources, a resin product (market recovered product) that has been used once is made into a molten resin using an extruder, and a pelletized or sheeted recycled resin is obtained therefrom, that is, a resin. Today's recycling system is an important system, and the social demand for it is expected to become higher in the future. Moreover, since it is predicted that the use of the recycled resin in the form of pellets or sheets will be further expanded, the quality of the recycled resin is expected to be higher than the current level.

  In order to obtain a higher quality recycled resin, it is necessary to remove volatile components as much as possible. In other words, the resin deteriorates when subjected to a thermal history or shearing force that rebounds, and the ratio of volatile components (for example, residual monomers) formed by the decomposition of the resin increases. Further, in the process of using a resin product as a product, some volatile components may adhere to the resin product.

  The presence of such volatile components is not a particular problem in current recycling systems where the number of recycling is relatively small. Moreover, there is no special problem from the use of the recycled resin currently performed. However, when more frequent recycling of resin is required in the future, or when higher quality recycled resin is required in relation to the application, volatilization of recycled resin Reducing the ingredients as much as possible is considered a consideration.

  An object of the present invention is to solve the above-mentioned problems that are expected to occur in the future. Specifically, by removing the volatile components contained in the recycled resin almost completely, a higher quality can be obtained. It is an object of the present invention to provide a multistage thermoplastic resin extrusion apparatus capable of producing a recycled resin and a thermoplastic resin extrusion method using the apparatus.

  In order to solve the above problems, a multi-stage thermoplastic resin extrusion apparatus according to the present invention includes a cylinder having a hopper into which raw materials are charged, a screw that transports the raw material supplied into the cylinder while compressing and melting, and a melting A first thermoplastic resin extruder having an extrusion port through which extruded resin is extruded, a cylinder having a molten resin inlet for taking in the molten resin extruded from the extrusion port of the first thermoplastic resin extruder, and the inside of the cylinder A multi-stage thermoplastic resin extrusion device comprising at least a second thermoplastic resin extruder provided with a screw for molten resin transfer for transferring the molten resin supplied to and an extrusion port through which the molten resin is extruded, The molten resin does not come into contact with outside air between the extrusion port of the first thermoplastic resin extruder and the molten resin intake port of the second thermoplastic resin extruder. Are connected by a connecting portion which can pass through a state, a part of the connecting portion, characterized in that the decompression chamber is formed.

  In the multistage thermoplastic resin extrusion apparatus according to the present invention, when the molten resin extruded from the first thermoplastic resin extruder contains a volatile component, the molten resin passes through the decompression chamber provided in the connecting portion. In the process, volatile components are removed from the molten resin. The molten resin from which the volatile components have been removed is homogenized in the process of passing through the second thermoplastic resin extruder, and is quantitatively discharged from the extrusion port. Thereafter, a cooling process and a shredding process similar to the conventional ones are performed, and a recycled resin formed into a sheet or pellet is formed. Since the produced pellets or sheets are almost completely free of volatile components, they become extremely high quality recycled resin pellets or recycled resin sheets.

  In the multistage thermoplastic resin extrusion apparatus according to the present invention, the first thermoplastic resin extruder has a main purpose of giving a high compressive force and heat to the pulverized resin as a raw material to obtain a molten resin. Therefore, it is desirable to attach the key jacket having the specially shaped protrusion described in Patent Document 1 to the upstream portion of the cylinder, that is, the portion close to the hopper. Thereby, the compression efficiency in a screw can be made higher and the conversion of a pulverized resin to a molten resin is further promoted. Further, the first thermoplastic resin extruder may have a single screw form, a twin form, or the like. Further, a vent port for deaeration is usually provided in the cylinder.

  The second thermoplastic resin extruder is mainly intended to extrude a molten resin having a reduced volatile content from its extrusion port while controlling the temperature and quantitatively.

  In a preferred aspect of the multistage thermoplastic resin extrusion apparatus according to the present invention, a diversion unit capable of diverting the molten resin passing therethrough into a plurality of pieces in the flow direction is interposed in the decompression chamber. In this aspect, the molten resin is divided into a plurality of pieces by passing through the diverting means, whereby the surface area of the molten resin increases as the number of divided pieces increases. Therefore, it is possible to stabilize the volatilization of volatile components from the molten resin, and to increase the volatilization amount. Although there is no restriction | limiting in the specific shape of the said diversion means, As an example, the several slit formed in the plate-shaped object, the several through-hole, etc. are mentioned.

  In a preferred aspect of the multistage thermoplastic resin extrusion device according to the present invention, the pressure in the decompression chamber is between the extrusion port of the first thermoplastic resin extruder and the inlet portion of the decompression chamber in the connecting portion. A pressure adjusting means is provided for adjusting the influence on the first thermoplastic resin extruder. By providing this pressure adjusting means, it is possible to maintain the head pressure of the first thermoplastic resin extruder at a predetermined pressure or higher despite the presence of the decompression chamber. Thereby, it is possible to avoid destabilizing the delivery of the molten resin from the first thermoplastic resin extruder under the influence of the reduced pressure in the reduced pressure chamber. Thereby, it becomes possible to make the feeding of the molten resin to the second thermoplastic resin extruder uniform and stable.

  The pressure adjusting means may be formed as long as it is a means capable of controlling the pipe diameter between the extrusion port of the first thermoplastic resin extruder and the inlet part of the decompression chamber in the connecting portion. A baffle plate such as a melt throughr or a choke valve may be arranged, or may be formed by arranging a baffle plate such as a screen mesh at the extrusion port of the first thermoplastic resin extruder. .

In the multistage thermoplastic resin extrusion apparatus according to the present invention, the pressure in the decompression chamber is experimentally set in consideration of how much volatile components are removed from the molten resin passing therethrough in the actual apparatus. However, as an example, when the atmospheric pressure is 760 mmHg, the decompression chamber is maintained at 10 ^{−3 to} 80 mmHg. The decompression of the decompression chamber can be established by evacuating the decompression chamber using, for example, a vacuum pump, but if the high degree of vacuum is maintained over a long period of time, the operation cost of the apparatus increases. It is preferable to maintain in the range of 0.1 to 50 mmHg.

  In the second embodiment of the multi-stage thermoplastic resin extrusion apparatus according to the present invention, the multi-stage thermoplastic resin extrusion apparatus is configured such that the cylinder of the second thermoplastic resin extruder is connected to the molten resin intake port. A seal resin inlet is provided at a position separated by a predetermined distance in the direction opposite to the extrusion port side, and the molten resin transfer screw receives the seal resin supplied from the seal resin inlet to the screw for transferring the molten resin. A seal resin transfer screw portion that transfers toward the inlet is integrally provided, and a pitch of the seal resin transfer screw portion is smaller than a pitch of the molten resin transfer screw.

  In the multistage thermoplastic resin extrusion apparatus according to the present invention, evacuation is performed by, for example, a vacuum pump in order to maintain the decompression chamber at a pressure lower than atmospheric pressure during operation. The decompression chamber communicates with the cylinder of the second thermoplastic resin extruder, and the decompression chamber is evacuated when the recycled molten resin is extruded from the second thermoplastic resin extruder for a long time. By the operation, it is possible that outside air is drawn into the decompression chamber through the cylinder from the upstream side of the screw for transferring the molten resin. When such outside air is drawn in, it becomes difficult to maintain the decompression chamber in a constant high vacuum state, and removal of volatile components may become unstable, and the extruded state of the molten resin may also become unstable. .

  In order to avoid this, in the second stage multi-stage thermoplastic resin extrusion apparatus, a seal resin inlet is provided in the cylinder of the second thermoplastic resin extruder, and the screw for transferring the molten resin is provided in the cylinder. A seal resin transfer screw portion for transferring the seal resin supplied from the seal resin intake port toward the molten resin intake side is provided integrally, and the pitch of the seal resin transfer screw portion is the pitch of the screw for transferring the molten resin. It is characterized by being made smaller.

  The seal resin supplied from the seal resin inlet is heated, compressed and sheared into a molten resin in the process of being transferred toward the molten resin inlet by the seal resin transfer screw part. As a result, an airtight portion is formed by the molten seal resin between the seal resin transfer screw portion and the inner wall of the cylinder. Therefore, when evacuating the decompression chamber, it is possible to reliably prevent outside air from flowing into the decompression chamber through the cylinder from the upstream side of the screw for transferring the molten resin. Thereby, in the multistage thermoplastic resin extrusion apparatus according to the present invention, it becomes easy to maintain the pressure in the decompression chamber at a required high vacuum state, and a high removal efficiency of volatile components can be achieved. The extruded state can be made more stable.

  In a preferred aspect of the second stage multistage thermoplastic resin extrusion apparatus, the groove depth of the transfer groove of the seal resin transfer screw portion is deep on the transfer start side and shallow on the end side. . In this type of multistage thermoplastic resin extrusion device, the pitch of the seal resin transfer screw portion is smaller than the pitch of the screw for transferring the molten resin, and is deep at the transfer start side and shallow at the end side. Further, compression and melting of the seal resin transferred by the seal resin transfer screw part can be advanced with higher efficiency, and a higher sealing effect can be obtained.

  In a preferred embodiment of the second-stage multi-stage thermoplastic resin extrusion device, the transfer groove of the seal resin transfer screw part is composed of a feed part having the deepest groove depth and a compression part in which the groove depth becomes gradually shallower. It is good also as a structure. In this aspect, by providing the seal resin inlet facing the feed portion, a larger amount of seal resin can be stably taken into the seal resin transfer screw portion, and the groove depth becomes gradually shallower. By providing the compression portion on the downstream side in the feed direction, compression and melting of the taken-in sealing resin can be advanced with higher efficiency. A metalling part having the shallowest groove depth may be provided at a predetermined length on the downstream side in the feed direction of the compression part. In this case, the amount of molten sealing resin supplied to the screw for molten resin transfer Can be reliably quantified.

  In one aspect of the second-stage multistage thermoplastic resin extrusion apparatus, a mechanical seal structure is formed between the rear end portion of the seal resin transfer screw portion and the cylinder. In this aspect, it is possible to reliably prevent the seal resin supplied from the seal resin intake from leaking out from the rear end side of the seal resin transfer screw portion. Of course, it is possible to provide a suitable sealing structure such as a lip seal structure instead of the mechanical seal structure, but since the region to be sealed is placed in a high temperature environment, it is particularly preferable to provide the mechanical seal structure. .

  In the second-stage multi-stage thermoplastic resin extrusion device, the seal resin is pulverized to an appropriate size, as in the case of the raw material resin, and then charged from the seal resin inlet. The seal resin that has been charged and melted at the seal resin transfer screw portion merges with the molten resin taken in from the molten resin intake port of the second thermoplastic resin extruder, and is then kneaded by the molten resin transfer screw. And extruded from the extrusion port of the second thermoplastic resin extruder. Therefore, in order to produce a high-quality recycled resin, a raw material hopper of the first thermoplastic resin extruder can be used, although any resin material can be used for the sealing resin in order to simply obtain a sealing effect. It is very preferable to use as the sealing resin a resin material of the same type as the raw material resin charged in At that time, the sealing resin may be supplied to the sealing resin transfer screw part in a pellet state or in a molten state.

  In the thermoplastic resin extrusion method using the multistage thermoplastic resin extrusion apparatus according to the second aspect of the present invention, the pulverized resin supplied to the hopper of the first thermoplastic resin extruder, and the second resin The same kind of thermoplastic resin material is used for the seal resin introduced into the seal resin inlet of the thermoplastic resin extruder. By adopting this extrusion method, a higher quality recycled resin can be obtained effectively.

  In the above-described extrusion mode, at the beginning of the extrusion operation, the same kind of seal resin prepared separately is used as the seal resin to be introduced into the seal resin intake port, in a stable state from the second thermoplastic resin extruder. When the recycled resin comes to be obtained, the resin extruded from the second thermoplastic resin extruder is pelletized, or a part of the pulverized product after being formed into a sheet, or in a molten state Thus, it is a more preferable aspect that the resin is introduced into the seal resin inlet of the second thermoplastic resin extruder and used as the seal resin. By adopting this method, recycled resin from which volatile components have been removed is used as a sealing resin, so that it is possible to improve the recycling efficiency and more easily and stably produce a high-quality recycled resin. It becomes possible.

  By using the multistage thermoplastic resin extrusion apparatus according to the present invention, a high-quality recycled resin from which volatile components are almost completely removed can be stably obtained, and the regeneration efficiency can be improved.

The figure explaining an example of the multistage type thermoplastic resin extrusion apparatus of the 1st form by this invention. The figure which shows some examples of the diversion means arrange | positioned at a decompression chamber. The figure which shows an example of the key jacket with which the upstream part of a cylinder is mounted | worn. The figure explaining an example of the multistage type thermoplastic resin extrusion apparatus of the 2nd form by this invention. The enlarged view for demonstrating the sealing resin extrusion part in the multistage type thermoplastic resin extrusion apparatus shown in FIG. The figure explaining the multistage type thermoplastic resin extrusion apparatus used for the comparative experiment.

  Hereinafter, a preferred embodiment of a multistage thermoplastic resin extrusion apparatus according to the present invention will be described with reference to the drawings, taking as an example the case of using two extruders connected together.

  As shown in FIG. 1, the first embodiment of the thermoplastic resin extrusion apparatus A1 includes a first thermoplastic resin extruder 10 and a second thermoplastic resin extruder 60. The two thermoplastic resin extruders 10 and 60 themselves may be conventionally known extruders described in Patent Document 1 or 2 described above. In this example, the first thermoplastic resin extruder 10 includes a hopper 20 into which a raw material which is a pulverized resin is charged, a cylinder 30 to which the raw material outlet side of the popper 20 is connected, and a raw material supplied into the cylinder 30. A screw 40 that is compressed and transported while melting and an extrusion port 50 through which the molten resin is extruded are provided. Although not shown, appropriate heating means such as a band heater for heating and melting the raw material is disposed on the outer periphery of the cylinder 30.

  The hopper 20 may be in any form as long as it can supply the raw material, which is a pulverized resin, into the cylinder 30. In the illustrated example, a supply screw 21 is provided in the hopper 20 so that a raw material, for example, a foamed resin pulverized product, can be press-fitted into the cylinder 30 by a certain amount. As an example of this type of hopper, one described in Japanese Patent No. 2526417 can be used.

  The cylinder 30 is a cylindrical body, and a screw 40 that is rotationally driven by an appropriate drive source 31 is interposed therein. On the upstream side of the cylinder 30, the raw material outlet side of the popper 20 is opened, and a raw material which is pulverized resin is quantitatively supplied by the supply screw 21. And the raw material supplied in the cylinder 30 is transferred toward the left direction in the figure by the screw 40.

  In this example, the cylinder 30 is a first cylinder as shown in FIG. 3 (key jacket: a cylinder in an extruder having a groove, and several to several tens of cylinders in the direction of resin flow from the raw material inlet. ) And a second cylinder 33 connected thereto. As shown in FIG. 3 (a) and a side view in FIG. 3 (b), the first cylinder 32 has a raw material supply port 34 on the upstream side, and the raw material outlet of the popper 20 there. The side is connected. In this example, the inner peripheral portion of the upstream portion as viewed in the raw material transfer direction of the first cylinder 32 has a bottom surface having a diameter larger than the inner diameter of the first cylinder 32 and sags along the transfer direction. A plurality of rows of protrusions 35 having a conical surface as a base surface and projecting inward of the cylinder, extending along the transfer direction, and having a shape whose width is narrower toward the distal end and lower toward the downstream, Projections are provided at predetermined angular intervals. In addition, the 1st cylinder 32 formed by providing the protrusion of such a form is described in above-mentioned patent document 1, The shape is not restricted to what is shown in FIG.

  The rear end portion of the first cylinder 32 in the raw material transfer direction and the front end portion of the second cylinder 33 in the raw material transfer direction are integrally connected by both flanges 36 and 41, and the rear end of the second cylinder 33 in the raw material transfer direction. The end is an extrusion port 50.

  The screw 40 is arranged so as to extend over almost the entire length in the first cylinder 32 and the second cylinder 33, and includes a support shaft portion 42 and a spiral blade 43 attached to the outer peripheral surface of the support shaft portion 42. In this example, the support shaft portion 42 includes a first support shaft portion 42a on the upstream side in the raw material transfer direction and a second support shaft portion 42b on the downstream side connected thereto. The first support shaft portion 42a has a small diameter on the upstream side, and gradually increases in diameter toward the downstream side. The second support shaft portion 42b has a small diameter on the upstream side, and gradually increases in diameter toward the downstream side. A vent port 37 that functions as an air vent is provided in the vicinity of the connecting portion of the second cylinder 33 between the first support shaft portion 42a and the second support shaft portion 42b.

  The extrusion port 50 is a portion where molten resin is extruded from the cylinder 30 and has a sufficiently smaller diameter than the inner diameter of the cylinder 30. If necessary, an appropriate screen is interposed in the extrusion port 50 to eliminate the fixed matter in the molten resin. Moreover, the pressure gauge 51 is provided in the vicinity of the extrusion port 50, and the extrusion pressure of molten resin is measured.

  The second thermoplastic resin extruder 60 also includes a cylinder 70, a screw 80 arranged in the cylinder 70 for transferring the molten resin, and an extrusion port 90 for the molten resin. The screw 80 is rotationally driven by an appropriate drive source 61. Although not shown, appropriate heating means such as a band heater for controlling the temperature of the molten resin is disposed on the outer periphery of the cylinder 70. The cylinder 70 has a molten resin intake 71 on the upstream side, and the molten resin extruded from the extrusion port 50 of the first thermoplastic resin extruder 10 is melted through a connecting portion 100 described later. Enter the resin inlet 71. The molten resin that has entered is quantitatively sent to the extrusion port 90 by the rotation of the screw 80 for transferring the molten resin, and is quantitatively discharged from the extrusion port 90 through a mold (not shown).

  In the illustrated example, an appropriate exchangeable screen changer 91 is also inserted in the extrusion port 90 to eliminate the fixed matter in the molten resin. Further, a gear pump 92 is attached downstream of the screen changer 91 to further quantify the extrusion amount of the molten resin. Here again, the screen changer 91 and the gear pump 92 can be omitted. The molten resin extruded through the mold from the extrusion port 90 is cooled by a cooling device (not shown) to form a sheet, or further cut into pellets by a cutter (not shown).

  Next, the connecting part 100 will be described. The connecting part 100 is constituted by a pipe line part 110 connected to the above-described extrusion port 50 in the first thermoplastic resin extruder 10 and a decompression chamber 120 where a downstream end 111 of the pipe line part 110 is opened. . The downstream end of the decompression chamber 120 is connected to the resin inlet 71 of the cylinder 70 described above. The entire connecting portion 100 has a sealed structure so that the molten resin passing through the inside can pass without contacting with the outside air.

  The diameter of the pipe section 110 is the same as or substantially the same as the diameter of the extrusion port 50 and is not essential, but in this example, the pressure acting on the molten resin passing through the pipe section 110 is adjusted in the middle. A pressure adjusting means 112 capable of performing the above is provided. The pressure adjusting means 112 is preferably a choke valve capable of variably controlling the diameter of the pipe line part 110 from the viewpoint of ease of configuration and ease of operation. A baffle plate such as a melt throughr may be disposed on the surface. The pressure adjusting means is not provided in the pipe section 110 as in the illustrated example, but in the breaker plate in the extrusion port 50 of the first thermoplastic resin extruder 10 or in the form of a screen mesh in the screen changer 91 described above. The intended purpose can also be achieved by arranging the plates.

  The decompression chamber 120 described above is connected to a vacuum pump (not shown), and the interior of the chamber is maintained at a required reduced pressure by a control device (not shown). Further, although not essential, in the example shown in the figure, the flow dividing means 130 is attached to the downstream end 111 of the pipe line part 110 opened in the decompression chamber 120. The diversion unit 130 diverts the molten resin flowing out from the pipe line part 110 as a single flow into a plurality of flows, and is exposed to a reduced pressure in the decompression chamber 120 by the diversion. The surface area of the molten resin is increased.

  FIG. 2 shows some specific examples of the flow dividing means 130. FIG. 2A is a side view of the flow dividing means 130 attached to the lower end portion of the pipeline portion 110. In this example, the flow dividing means 130 has a cylindrical portion 131, and a bottom plate 132 that closes the cylindrical portion 131 has a plurality of circular or elliptical shapes as shown in FIG. A small opening 133 is formed. The molten resin from the pipe line part 110 is divided into a number corresponding to the number of openings. In FIG. 2C, a large number of slits 134 are formed in the bottom plate 132. In this example, the molten resin is divided according to the number of slits 134.

  FIGS. 2D and 2E are examples in the case where the overall shape of the flow dividing means 130 is a box shape, and a large number of slits 134 are formed in a rectangular bottom plate 132. Even in this case, the molten resin is divided into a number corresponding to the number of slits 134.

  Next, the operation of the first-stage multistage thermoplastic resin extrusion apparatus A1 will be described. First, the resin material to be recycled is pulverized to an appropriate size. The resin material may be a foamed resin or a non-foamed resin. When a pulverized product of foamed resin is used as a raw material, it is desirable to use a push-type hopper 20 provided with a supply screw 21 as shown in FIG. 1, but a popper not provided with a supply screw 21 may also be used. it can.

  The raw material, which is a pulverized resin, is supplied from the hopper 20 into the cylinder 30. The supplied raw material is sent by the screw 40 toward the extrusion port 50 through the cylinder 30 while being heated by a heating device (not shown). A compressive force corresponding to the shape of the screw 40 acts on the raw material, and the pulverized resin raw material is gradually reduced in volume and melted by the compression and shearing force. When the pulverized product of the foamed resin is a raw material, deaeration from the raw material gradually proceeds. The pressure acting temporarily at the connecting portion between the first cylinder 32 and the second cylinder 33 is reduced, and most of the air, moisture, volatile components, etc. in the raw material are degassed from the vent port 37.

  The degassed molten resin flows into the pipe part 110 of the connecting part 100 from the extrusion port 50 of the cylinder 30 by the pushing force of the cylinder 30, and further passes through the pipe part 110 to the downstream end thereof. 111 is pushed into the decompression chamber 120. A diversion means 130 is provided at the extrusion port in the decompression chamber 120, and the molten resin extruded (outflowed) as one flow from the pipe line portion 110 is diverted into a plurality. Thereby, the surface area of the molten resin is increased according to the number of diverted pipes.

  On the other hand, the inside of the decompression chamber 120 is decompressed to a degree of vacuum required for the action of the vacuum pump, and the molten resin having a large surface area is exposed to a decompressed state. Thereby, the volatile components present on the surface and inside of the molten resin are effectively removed from the resin. Then, the molten resin from which the volatile components have been removed flows into the cylinder 70 from the resin intake port 71 of the second thermoplastic resin extruder 60, and the molten resin that has entered enters the screw 80 for transferring the molten resin. Is quantitatively sent to the extrusion port 90 by the rotation of the nozzle, and is quantitatively discharged from a mold (not shown) provided when necessary through the extrusion port 90. The molten resin discharged quantitatively from the extrusion port 90 is one from which volatile components have been removed, and a high-quality recycled resin can be obtained.

  In the example shown in the figure, the advantage that the compression effect with respect to the distance of the screw 40 can be enhanced by providing the projection 35 having a special shape as shown in FIG. 3 on a part of the first cylinder (key jacket) 32. There is. However, depending on the type of raw material, its use can be omitted.

In addition, by providing the pressure adjusting means 112 in the middle of the pipe line part 110, it is possible to block the first thermoplastic resin extruder 10 from being affected by the pressure in the decompression chamber 120. The required pressure in the thermoplastic resin extruder 10 can be maintained. The pressure gauge 51 measures the extrusion pressure of the molten resin. If the measured value is lowered, the influence of the pressure in the decompression chamber 120 is influenced in the first thermoplastic resin extruder 10. Therefore, the pressure adjusting means 112 is appropriately adjusted to block the influence. As an example, the pressure adjusting means 112 is appropriately adjusted so that the head pressure of the first thermoplastic resin extruder 10 is maintained at, for example, 5 kg / cm ² or more.

  It is desirable that the decompression chamber 120 has a space that can sufficiently evacuate volatile components, and has a size such that a plurality of resin flows that do not come into contact with each other. The residence time until the diverted molten resin comes out of the diverting means 130 and contacts the screw 80 of the second thermoplastic resin extruder 60 is generally 1 second or longer, preferably 1.5 seconds or longer. . This residence time can be adjusted by controlling the shape and size of the decompression chamber 120 and the amount of extrusion. When the residence time in the decompression chamber 120 is insufficient, a baffle device such as a wire mesh can be set, and if necessary, this can be set in multiple stages to adjust the residence time.

  Next, with reference to FIG. 4 and FIG. 5, a second-stage multistage thermoplastic resin extrusion apparatus A <b> 2 according to the present invention will be described. The second-stage multistage thermoplastic resin extrusion apparatus A2 is characterized in that a seal mechanism B is further provided on the upstream side of the molten resin transfer screw 80 in the feed direction. Other configurations are the same as those of the multistage thermoplastic resin extrusion apparatus A1 of the first embodiment, and detailed description thereof is omitted by attaching the same reference numerals.

  The seal mechanism B includes a seal resin transfer screw portion 82 formed integrally with the same rotation axis on the upstream side in the feed direction of the molten resin transfer screw 80, and a portion of the seal resin transfer screw portion 82 And a cylinder portion 72 for sealing resin corresponding to the above. The pitch of the sealing resin transfer screw portion 82 is made smaller than the pitch of the screw 80 for transferring the molten resin. The cylinder 70 includes a seal resin cylinder portion 72 corresponding to the seal resin transfer screw portion 82 and a molten resin cylinder portion 73 corresponding to the molten resin transfer screw 80 portion. . As shown in FIG. 5, the front end of the sealing resin cylinder portion 72 and the rear end of the molten resin cylinder portion 73 are integrally connected by both flanges 74 and 75. The entire cylinder 70 may be formed as one member.

  The above-mentioned molten resin inlet 71 is formed in the vicinity of the upstream end of the molten resin cylinder portion 73, and is a position away from the molten resin inlet 71 by a predetermined distance in the direction opposite to the extrusion port 90 side. In other words, a seal resin inlet 76 is formed between the molten resin inlet 71 and the screw bearing portion 77 in the vicinity of the upstream end of the seal resin cylinder portion 72. Further, an appropriate sealing means 78 such as a mechanical seal or a lip seal for sealing the gap between the seal resin transfer screw portion 82 and the cylinder portion 72 for the seal resin is provided. Is provided.

  As shown in FIG. 5, in this example, the feed groove formed continuously in the seal resin transfer screw portion 82 is divided into three regions 82a, 82b, and 82c. The region 82a is a region corresponding to the vicinity of the seal resin intake 76 and has the deepest groove depth. This area is called a feed section. The region 82b is a region continuing to the downstream side in the feed direction of the region 82a, and the groove depth becomes gradually shallower toward the downstream side. This area is called a compression section. The region 82c is a region that continues downstream in the feed direction of the region 82b, and has a shallowest groove depth and an integral depth over the entire region. This area is called a meta ring part. The region 82c can be omitted.

  Further, a hopper 62 is attached to the seal resin intake 76, and an appropriate seal resin filled in the hopper 62 passes through the seal resin intake 76 and the region 82 a of the seal resin transfer screw portion 82. Is supplied to the part (feed part). The supplied sealing resin is gradually reduced in volume and melted by receiving compression and shearing force when passing through the region 82b (compression portion). Then, the molten resin is quantified by passing through the region 82c (meta ring part), and the fixed amount of molten resin flows into the most upstream area of the screw 80 for transferring the molten resin. The melted sealing resin forms a hermetically sealed state between the outer periphery and groove of the sealing resin transfer screw portion 82 and the inner peripheral surface of the sealing resin cylinder portion 72.

  After the molten sealing resin that has flowed into the uppermost stream region of the molten resin transfer screw 80 merges with the molten resin flowing into the molten resin cylinder portion 73 from the molten resin inlet 71 through the connecting portion 100, While being kneaded by the screw 80 for molten resin transfer, it is extruded from the extrusion port 90 of the second thermoplastic resin extruder 60.

  Even when the molten resin is continuously discharged quantitatively from the extrusion port 90, the inside of the decompression chamber 120 is continuously decompressed to a required degree of vacuum by the action of a vacuum pump. Depending on the degree of decompression of the decompression chamber 120, outside air may be drawn into the decompression chamber 120 from the region between the resin inlet 71 of the second thermoplastic resin extruder 60 and the drive source 61. In order to avoid this, in the second-stage multistage thermoplastic resin extrusion apparatus A2, the sealing resin is supplied from the hopper 62 through the sealing resin inlet 76 into the sealing resin cylinder portion 72. The As described above, the supplied sealing resin is heated, compressed, and sheared in the process of moving in the sealing resin cylinder portion 72 by the sealing resin transfer screw portion 82, and becomes a high-pressure molten resin. The seal resin provides a hermetically sealed state between the outer periphery and groove of the seal resin transfer screw portion 82 and the inner peripheral surface of the seal resin cylinder portion 72. Thereby, it is possible to reliably prevent outside air from flowing into the decompression chamber 120.

  In the extrusion of the thermoplastic resin by the multistage thermoplastic resin extrusion apparatus A2 of the second embodiment, the kind of the sealing resin supplied from the sealing resin inlet 76 of the second thermoplastic resin extruder 60 is from the hopper 20 to the cylinder. It is the same kind of resin as the pulverized resin supplied into the interior 30. Since the resin type is the same, a high-quality recycled resin can be obtained. When the recycled resin is continuously discharged from the extrusion port 90, a part of the recycled resin discharged from the extrusion port 90 or pelletized sheet is used. The method of supplying from the seal resin inlet 76 of the second thermoplastic resin extruder 60 is more preferable because the regeneration efficiency can be improved, and a higher quality recycled resin can be obtained.

  The amount of the sealing resin supplied from the sealing resin inlet 76 of the second thermoplastic resin extruder 60 is determined by the molten resin during operation, the outer periphery and grooves of the sealing resin transfer screw portion 82 and the sealing resin cylinder portion 72. It is necessary that the amount be such that a sealed state is formed in such a manner that outside air is not drawn into the decompression chamber 120 between the peripheral surfaces. It is preferable to use about 4 to 20 parts by weight of the sealing resin with respect to 100 parts by weight of the resin supplied from the hopper 20 into the cylinder 30.

  Next, advantages of the present invention will be described with reference to examples and comparative examples.

[Material adjustment]
Toluene and ethanol as a volatile component are blended into 50 kg of flakes obtained by pulverizing an unused PSP (foamed polystyrene) molded product and its end materials, and mixed with extrusion flakes to give about 50 ppm of toluene and 50 ppm of ethanol. Then, the mixed flakes having a total volatile content of 100 ppm were used as an extrusion raw material.

[test]
A first thermoplastic resin extrusion apparatus A1 having the configuration described based on FIG. 1 is used, and the raw material is pressure-melted under the conditions shown in Tables 1 and 2 to provide a second thermoplastic resin extruder. Volatile components contained in the resin extruded from 60 were measured (Examples 1 to 13). However, a die having a nozzle shape and a slit-like die were selectively attached to the extrusion port 90 of the second thermoplastic resin extruder 60 without attaching the screen changer 91 and the gear pump 92.

  Further, as shown in FIG. 6, the decompression chamber 120 is removed from the thermoplastic resin extrusion apparatus A1 of the first embodiment having the configuration described based on FIG. 1, and the choke valve which is the pressure adjusting means 112 is fully opened. Using the apparatus in the state described above, pressure-melting was performed under the conditions shown in Table 3, and the volatile components contained in the resin extruded from the second thermoplastic resin extruder 60 were measured (Comparative Example). In FIG. 6, members having the same functions as those shown in FIG.

[Test results]
The test results are shown in Table 4.
In Table 1, Table 2, and Table 3, A to K mean the following contents, respectively.
A: Extrusion amount (Kg / h), which is the extrusion amount of the molten resin from the mold attached to the extrusion port 90 of the second thermoplastic resin extruder 60.
B: The form of the 1st thermoplastic resin extruder 10 and the outer diameter mm of the screw 40 are shown.
C: The dimension mm of the projection 35 in the first cylinder (key jacket) 32 when used, and is represented by width × thickness × length.
D: Pressure (kg / cm ² ) acting on the choke valve that is the pressure adjusting means 112, which is a measurement value of the pressure gauge 51.
E: Total area (cm ² ) of the openings formed in the bottom plate 132 in the flow dividing means 130, and “row” indicates a slit.
F: Internal dimension mm of the decompression chamber 120 having a cylindrical shape, which is represented by a diameter × length.
G: Degree of vacuum in the decompression chamber 120 (mmHg).
H: The form of the 2nd thermoplastic resin extruder 60 and the outer diameter mm of the screw 80 are shown.
I: Indicates the resin temperature (° C.) in the second thermoplastic resin extruder 60.
J: The inner diameter φ (mm) of the pipe section 110 of the connecting section 100 that connects the first thermoplastic resin extruder 10 and the second thermoplastic resin extruder 60.
K: The shape and dimensions of the mold attached to the extrusion port 90 of the second thermoplastic resin extruder 60. In the case of the nozzle, the inner diameter φ (mm) is shown, and in the case of the slit, the height mm × width mm is shown. Show.

[Discussion]
1. The amount of the volatile component in the comparative example is 85 ppm, and it can be seen that the volatile component is hardly removed from the obtained recycled resin in the multistage thermoplastic resin extrusion apparatus not provided with the “decompression chamber” in the present invention. On the other hand, when using a multistage thermoplastic resin extrusion apparatus equipped with a decompression chamber according to the present invention, the maximum amount of volatile components is 8.3 ppm (Example 10), and a high removal rate is obtained. Yes.

Further, from the above embodiment, in the present invention, the above-described diverting means is interposed in the decompression chamber, and the decompression is performed between the extrusion port of the first thermoplastic resin extruder and the inlet portion of the decompression chamber in the connecting portion. Providing pressure adjusting means for blocking the pressure of the chamber from affecting the first thermoplastic resin extruder, the cylinder of the first thermoplastic resin extruder is provided with a first cylinder (key jacket) 32. That is, maintaining the pressure in the decompression chamber at 10 ^{−3 to} 80 mmHg is a more preferable aspect.

A1 ... Multistage thermoplastic resin extrusion device of the first form,
A2 ... Second-stage multi-stage thermoplastic resin extrusion device,
B ... Sealing mechanism,
10 ... 1st thermoplastic resin extruder,
20 ... A hopper into which raw materials that are pulverized resin are charged
30 ... Cylinder of the first thermoplastic resin extruder,
32 ... 1st cylinder (key jacket),
35 ... projections formed on the first cylinder (key jacket),
37 ... Vent mouth,
40 ... A screw that compresses and melts the raw material supplied in the cylinder,
50. Molten resin extrusion port,
51 ... Pressure gauge,
60 ... Second thermoplastic resin extruder,
62 ... Hopper into which sealing resin is charged,
70 ... cylinder of the second thermoplastic resin extruder,
71: Resin intake,
72 ... cylinder part for sealing resin,
73 ... Cylinder part for molten resin,
76 ... Seal resin inlet,
77 ... Screw bearing,
78 ... Sealing means,
80 ... screw for molten resin transfer,
82 ... Seal resin transfer screw part,
82a, 82b, 82c ... three regions of the seal resin transfer screw part,
90 ... Molten resin extrusion port,
100 ... connection part,
110 ... the pipe part of the connecting part,
112 ... Pressure adjusting means (choke valve),
120... A decompression chamber in which the downstream end of the pipe section is opened,
130 ... Diversion means,
131 ... the cylindrical part of the diversion means,
132 ... bottom plate for closing the cylindrical part,
133: an opening formed in the bottom plate,
134: A slit formed in the bottom plate.

Claims (8)

A first thermoplastic resin extruder having a cylinder having a hopper into which the raw material is charged, a screw that compresses and feeds the raw material supplied into the cylinder, and an extrusion port through which the molten resin is extruded; A cylinder having a molten resin inlet for taking in the molten resin extruded from the extrusion port of the thermoplastic resin extruder 1, a screw for transferring a molten resin for transferring the molten resin supplied into the cylinder, and the molten resin are extruded. A multi-stage thermoplastic resin extrusion device comprising at least a second thermoplastic resin extruder having an extrusion port,
The extrusion port of the first thermoplastic resin extruder and the molten resin intake port of the second thermoplastic resin extruder are connected by a connecting portion through which the molten resin can pass in a state where the molten resin does not contact with the outside air, A multistage thermoplastic resin extrusion apparatus, wherein a decompression chamber is formed in a part of the connecting portion.   2. The multistage thermoplastic resin extrusion according to claim 1, wherein the decompression chamber is provided with diversion means capable of diverting a plurality of molten resins passing therethrough in a flow direction. apparatus.   Between the extrusion port of the first thermoplastic resin extruder and the inlet part of the decompression chamber at the connecting portion, the pressure of the decompression chamber affects the inside of the first thermoplastic resin extruder. 3. The multistage thermoplastic resin extrusion apparatus according to claim 1, further comprising pressure adjusting means for adjusting. The multistage thermoplastic resin extrusion apparatus according to any one of claims 1 to 3, wherein the pressure in the decompression chamber is maintained at 10 ^{-3 to} 80 mmHg when 1 atmosphere is 760 mmHg. .   The cylinder of the second thermoplastic resin extruder has a seal resin inlet at a position away from the molten resin inlet by a predetermined distance in a direction opposite to the outlet side, and is used for transferring the molten resin. The screw is integrally provided with a seal resin transfer screw portion for transferring the seal resin supplied from the seal resin intake port toward the molten resin intake port, and the pitch of the seal resin transfer screw portion is the melting point. The multistage thermoplastic resin extrusion apparatus according to any one of claims 1 to 4, wherein the multistage thermoplastic resin extrusion apparatus is smaller than a pitch of a screw for resin transfer.   6. The multistage thermoplastic resin extrusion apparatus according to claim 5, wherein the depth of the transfer groove of the seal resin transfer screw portion is deep on the transfer start side and shallow on the end side.   A method for extruding a thermoplastic resin by a multistage thermoplastic resin extrusion apparatus according to claim 5 or 6, wherein the pulverized resin supplied to a hopper of the first thermoplastic resin extruder, and the second resin A method for extruding a thermoplastic resin, wherein the same kind of thermoplastic resin material is used for the seal resin introduced into the seal resin inlet of the thermoplastic resin extruder.   A method for extruding a thermoplastic resin by a multistage thermoplastic resin extrusion apparatus according to claim 7, wherein a part of the resin extruded from the second thermoplastic resin extruder is extruded into the second thermoplastic resin. A method for extruding a thermoplastic resin, characterized in that the thermoplastic resin is used as a sealing resin introduced into the sealing resin inlet of the machine.

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