JP6976690B2 - Equipment for producing foamable thermoplastic resin particles and method for producing foamable thermoplastic resin particles - Google Patents

Description

The present invention relates to an apparatus for producing effervescent thermoplastic resin particles and a method for producing effervescent thermoplastic resin particles.

The thermoplastic resin foam molded product obtained by using the foamable thermoplastic resin particles is a well-balanced foam having light weight, heat insulating property, cushioning property, etc., and has been conventionally used as a food container box, a cold storage box, and a cushioning material. It is widely used as a material and as a heat insulating material for houses and the like.

In Patent Document 1, a foaming agent is added to and kneaded with a polystyrene resin in a resin supply device, and the foaming agent-containing molten resin is extruded into a cooling liquid from a die attached to the tip of the resin supply device, and at the same time, an extruded product. Disclosed is a method for obtaining foamable polystyrene-based resin particles by cutting and cooling and solidifying in a liquid.

Further, Patent Documents 2 and 3 disclose a technique for transporting a molten resin discharged from an extruder. Specifically, in Patent Documents 2 and 3, a molten resin whose physical properties or properties are not stable in a steady state at the initial stage of screw extruder operation is discharged to the outside by a divertor valve, and the discharged high-temperature resin is cut. A technique for cooling, solidifying, and transporting is disclosed.

Japanese Unexamined Patent Publication No. 2012-077114 Japanese Unexamined Patent Publication No. 2007-181949 Japanese Unexamined Patent Publication No. 2008-296467

In the granulation technology using a screw extruder connected to an underwater cutting device, molten resin whose properties are not stable, such as molten resin before start-up processing, is discharged by a diverter valve, but the discharged molten resin is discharged at high temperature. Therefore, the problem is that its handling is dangerous. In order to solve this problem, in the techniques disclosed in Patent Documents 2 and 3, the high-temperature molten resin discharged to the outside from the discharge port of the divertor valve is cut and then solidified by cooling water in a state of being exposed to the outside. By transporting things to the outside, high-temperature molten resin is handled safely.

By the way, when the polystyrene-based molten resin containing a foaming agent as described in Patent Document 1 is discharged to the outside from the discharge port of the diverter valve, the foaming agent dissolved in the molten resin is released and is flammable. There is a danger that gas will fill the area around the device. Therefore, when the polystyrene resin containing the foaming agent is discharged from the divertor valve, the techniques described in Patent Documents 2 and 3 cannot prevent the generation of flammable gas. Further, when the molten resin is discharged to the outside from the divertor valve, it becomes a bulky foam, so that there is a concern that the load of the transport work will increase if the discharge amount becomes enormous.

One aspect of the present invention realizes an apparatus for producing foamable thermoplastic resin particles provided with a transport means capable of safely isolating the foaming agent-containing molten resin discharged from the diverter valve, and a method for producing foamable thermoplastic resin particles. The purpose is to do.

In order to solve the above problems, the apparatus for producing foamable thermoplastic resin particles according to one aspect of the present invention includes a die having a plurality of holes, and the molten resin containing the thermoplastic resin and the foaming agent is passed through the die. A device for producing foamable thermoplastic resin particles for extruding and granulating the resin, which is connected to the upstream side of the die and includes a switching valve for switching between transfer of the molten resin to the die and discharge to the outside. It is characterized by being provided with a pipe for isolating the molten resin discharged to the outside by the switching valve to a space different from the space in which the apparatus is operated in the molten state.

Further, in order to solve the above problems, the method for producing foamable thermoplastic resin particles according to one aspect of the present invention includes an extrusion step of extruding a molten resin containing a foaming agent and a thermoplastic resin through a die. This is a method for producing thermoplastic resin particles, in which the resin particles are produced in a molten state by a discharge step of discharging the molten resin to the outside by a switching valve and a molten resin discharged to the outside before the extrusion step. It is characterized by including an isolation process for isolating the space into a space different from the space to be plasticized.

According to one aspect of the present invention, foamable thermoplastic resin particles can be safely produced.

It is a figure which shows the schematic structure of the manufacturing apparatus 100 of the foamable thermoplastic resin particle which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the state of the divertor valve 22 in the discharge process and the extrusion process, (a) shows the state of the divertor valve 22 in the discharge process, (b) shows the state of the divertor valve 22 in the extrusion process. show. It is a figure which schematically showed the schematic structure of the temperature control mechanism 24 which controls the temperature of the molten resin P flowing in a pipe 23. It is a figure which shows the schematic structure of the manufacturing apparatus 100A of the foamable thermoplastic resin particle which concerns on Embodiment 2 of this invention.

[Embodiment 1]
<Manufacturing equipment for effervescent thermoplastic resin particles>
Hereinafter, one embodiment of the present invention will be described in detail. FIG. 1 is a diagram showing a schematic configuration of an apparatus 100 for producing foamable thermoplastic resin particles according to the present embodiment. The manufacturing apparatus 100 is an apparatus for granulating foamable thermoplastic resin particles by extruding a molten resin containing a thermoplastic resin and a foaming agent (hereinafter, may be simply referred to as a molten resin) and cutting it in water. Is.

As shown in FIG. 1, the manufacturing apparatus 100 includes an extruder 10 for extruding molten resin, a die 20, a die holder 21, a cutter 3, a cutting chamber 4, a pipeline 5, and a water pump 6. A water tank 7, a dehydration processing unit 8, and a container 9 are provided.

A die holder 21 and a die 20 are provided on the downstream side of the extruder 10 in the extrusion direction of the molten resin. Of the die holder 21 and the die 20, the die 20 is provided on the most downstream side. The die 20 has a resin discharge surface 20a on which the molten resin extruded from the extruder 10 is discharged. The die holder 21 is a member that holds the die 20, and includes a divertor valve 22 (switching valve). That is, the divertor valve 22 is provided on the upstream side of the die 20. Further, a cutting chamber 4 is provided on the opposite side of the die 20 from the extruder 10. In the manufacturing apparatus 100, the molten resin flows toward the die 20 by extrusion by the extruder 10. From such a flow of molten resin, in the extruder 10 and the die 20, the side on which the molten resin is discharged is the downstream side, and the opposite side is the upstream side. Further, the side direction is perpendicular to the flow direction of the molten resin (extrusion direction of the molten resin) from the upstream side to the downstream side.

The extruder 10 is provided with a hopper 11 for supplying a thermoplastic resin and a foaming agent supply pipe 12 for supplying a foaming agent. The foaming agent supply pipe 12 is connected to a foaming agent storage unit (not shown). Then, the foaming agent stored in the foaming agent storage unit is supplied to the extruder 10 by the high-pressure pump 13 via the foaming agent supply pipe 12. In addition, in FIG. 1, one hopper 11 is provided for supplying the thermoplastic resin, but the number of hoppers 11 depends on the characteristics, type, number, etc. of the raw material of the foamable thermoplastic resin particles. It can be set as appropriate. Further, although the foaming agent supply pipe 12 is connected to the extruder 10, it may be connected to a member other than the extruder 10.

A pipeline 5 is connected to the cutting chamber 4. One end of the pipeline 5 is connected to the water tank 7 via the water supply pump 6. On the other hand, a dehydration processing unit 8 is provided at the other end of the pipeline 5. In the manufacturing apparatus 100, the water in the water tank 7 is supplied to the cutting chamber 4 by driving the water pump 6, and flows from the cutting chamber 4 to the dehydration processing unit 8.

The cutting chamber 4 is a chamber for bringing the water flow from the water tank 7 into contact with the resin discharge surface 20a of the die 20. A cutter 3 is housed in the cutting chamber 4. The cutter 3 is a member for cutting the molten resin discharged from the die hole (see FIG. 2) provided in the resin discharge surface 20a of the die 20 into particles.

In the manufacturing apparatus 100, the raw materials such as the thermoplastic resin supplied via the hopper 11 are melt-kneaded in the extruder 10. Then, while the melt-kneaded product is transferred to the die 20, the foaming agent is mixed from the foaming agent supply pipe 12 by the high-pressure pump 13. Then, the molten resin containing the thermoplastic resin and the foaming agent moves while being further kneaded and is extruded from the die holes of the die 20. Then, when the molten resin is discharged from the die hole of the resin discharge surface 20a of the die 20, it is cut into granules by the cutter 3 and granulated, and at the same time, it comes into contact with water circulating in the cutting chamber 4 and is rapidly cooled. To.

The effervescent thermoplastic resin particles thus granulated are carried from the cutting chamber 4 to the dehydration processing unit 8 through the pipeline 5 along with the flow of circulating water. Then, in the dehydration processing unit 8, it is separated from the circulating water and dehydrated and dried. The dried foamable thermoplastic resin particles are stored in the container 9.

The extruder 10 can be appropriately selected from conventionally known extruders according to the type of resin to be granulated and the like, and examples thereof include an extruder using a screw. As an extruder using a screw, for example, a single-screw extruder or a twin-screw extruder can be adopted, and when a twin-screw extruder is adopted, the screw rotation direction is different even if they are in the same direction. It doesn't matter if it is in the direction. Further, two or more extruders 10 may be provided. For example, when two extruders 10 are provided, it is possible to adopt a tandem type configuration in which two extruders 10 are connected in series.

When one extruder 10 is provided, there is an advantage that the residence time of the molten resin can be easily suppressed in a short time and the deterioration of the resin can be easily suppressed. On the other hand, when two or more extruders 10 are provided, there is an advantage that the resin and other additives can be more uniformly mixed. In consideration of such a thing, the configuration of the extruder 10 can be determined.

Here, the divertor valve 22 is a switching valve that switches between the transfer of the molten resin melt-kneaded by the extruder 10 to the die 20 and the discharge to the outside. If the physical properties or properties of the molten resin melt-kneaded by the extruder 10 are not stable in the steady state, the temperature of each part of the manufacturing equipment 100 is not stable in the steady state, and the die is manufactured due to poor cutting or blockage of the die holes. When the grains are temporarily stopped, the molten resin is discharged to the outside by the diverter valve 22 without being supplied to the die 20. Then, when the physical properties or properties of the molten resin and the temperature of each part of the manufacturing apparatus 100 are stabilized in a steady state, or when the cutting failure and the blockage of the die holes are eliminated and the granulation is restarted, the molten resin is a divertor valve. It is supplied to the die 20 by 22. The cutting defect can be eliminated by cleaning the cutting chamber 4 and the cutter 3. Hereinafter, the step in which the molten resin is discharged to the outside by the divertor valve 22 is referred to as a discharge step, and the step in which the molten resin is supplied to the die 20 by the diverter valve 22 is referred to as an extrusion step.

If necessary, equipment such as a gear pump, a screen changer, a static mixer, and a static cooler may be provided between the extruder 10 and the divertor valve 22.

FIG. 2 is a cross-sectional view showing the state of the divertor valve 22 in the discharge process and the extrusion process, FIG. 2 (a) shows the state of the divertor valve 22 in the discharge process, and FIG. 2 (b) shows the state of the divertor valve 22. The state of the divertor valve 22 in the extrusion process is shown. The die holder 21 is fixed to the downstream side of the extruder 10. Further, the die 20 is fixed to the portion of the die holder 21 opposite to the extruder 10. The divertor valve 22 provided in the die holder 21 is configured to be movable laterally.

As shown in FIGS. 2A and 2B, the die holder 21 is provided so as to communicate with the cylinder portion of the extruder 10, and the upstream side flow path 21a extending from the upstream side to the downstream side. And the downstream side flow path 21b is formed. Further, the divertor valve 22 has a first flow path 22a penetrating from the upstream side to the downstream side, and a second flow path 22b extending from the upstream side to the side and exiting to the side surface of the die holder 21. Then, in the die holder 21, the upstream side flow path 21a and the second flow path 22b are connected to each other according to the lateral movement of the divertor valve 22 ((a) in FIG. 2), and the upstream side flow path 21a. The downstream side flow path 21b is switched to a configuration ((b) in FIG. 2) relayed by the first flow path 22a.

In the discharge step shown in FIG. 2A, the upstream side flow path 21a and the second flow path 22b are connected to block the flow of the molten resin P to the downstream side flow path 21b, and the molten resin is blocked. P is discharged to the outside via the second flow path 22b. On the other hand, in the extrusion step shown in FIG. 2B, the upstream side flow path 21a and the downstream side flow path 21b are relayed by the first flow path 22a, so that the molten resin P is transferred to the downstream side flow path. It is transferred to the die 20 via 21b.

The die 20 is provided with a flow path 20b communicating with the downstream flow path 21b in a portion on the upstream side thereof. Further, in the flow path 20b, a conical convex portion 20c protruding to the upstream side is formed at a distance from the side wall of the flow path 20b. Further, a plurality of resin flow paths 20d are provided on the downstream side of the die 20. The resin flow path 20d is a flow path that communicates with the flow path 20b and extends to the die hole 20e of the resin discharge surface 20a, and extends in a direction orthogonal to the resin discharge surface 20a. Further, the resin flow paths 20d are arranged at regular intervals along the circumference centered on the central axis of the die 20. The die 20 is not particularly limited, and examples thereof include those having a die hole 20e having a diameter of 0.3 mm to 2.0 mm, preferably 0.4 mm to 1.0 mm.

In the extrusion step, as shown in FIG. 2B, the molten resin P that has passed through the downstream flow path 21b flows along the peripheral surface of the conical convex portion 20c in the flow path 20b. Then, it passes through the plurality of resin flow paths 20d and is discharged from the die holes 20e formed in the resin discharge surface 20a.

In the manufacturing apparatus 100, in the discharge process, as shown in FIG. 2A, the divertor valve 22 is moved to connect the upstream side flow path 21a and the second flow path 22b. Then, the molten resin P is discharged to the outside via the second flow path 22b.

Here, the molten resin P discharged to the outside is a thermoplastic molten resin mainly containing a foaming agent. Therefore, when the molten resin P is discharged to the outside from the discharge port of the divertor valve, the molten resin P becomes a foam and combustible gas is generated. Therefore, in the manufacturing apparatus 100 according to the present embodiment, a pipe 23 that is detachably connected to the outlet of the second flow path 22b of the divertor valve 22 is provided. As shown in FIG. 1, the pipe 23 extends to a space B different from the space A in which the manufacturing apparatus 100 is installed, and is a pipe for separating the molten resin from the space A to the space B in a molten state. be. Further, in the configuration shown in FIG. 2B, in the extrusion process, the pipe 23 is connected to the outlet of the second flow path 22b of the divertor valve 22 as in the discharge process. However, the configuration of the pipe 23 and the second flow path 22b in the extrusion step is not limited to the configuration shown in FIG. 2 (b). The pipe 23 may not be connected to the second flow path 22b in the extrusion process.

In the discharge step, the pipe 23 is connected to the second flow path 22b of the divertor valve 22 ((a) in FIG. 2). Therefore, the molten resin P discharged from the second flow path 22b passes through the pipe 23 without being exposed to the outside, and is isolated in a molten state in a space B different from the space A in which the manufacturing apparatus 100 is operated. To. Therefore, according to the present embodiment, the molten resin P discharged to the outside of the manufacturing apparatus 100 by the divertor valve 22 can be isolated in a space B different from the space A in the molten state. Since the molten resin P, which is in a molten state in which flammable gas is likely to be generated, can be isolated without being exposed to the outside, a large number of electric devices that can be ignition sources of the flammable gas for operating the manufacturing apparatus 100 are installed. It is possible to avoid the filling of the flammable gas in the space A. Therefore, since the manufacturing apparatus 100 is not operated in the space B, it is easy to take measures against ignition sources and ventilation measures, so that the foamable thermoplastic resin particles can be safely manufactured.

As shown in FIG. 3, the pipe 23 includes a temperature control mechanism 24 that controls the temperature of the pipe 23. In FIG. 3, the temperature control mechanism 24 is provided in the entire pipe 23, but the temperature control mechanism 24 is partially provided as long as the molten resin flowing through the pipe 23 does not solidify and cause pipe clogging. You may. The temperature control mechanism 24 includes a temperature measuring unit 25 that measures the temperature of the pipe 23, and a temperature control heating unit 26 that heats the pipe 23 to maintain it in a constant temperature range.

In the temperature control using the temperature control mechanism 24, the temperature of the pipe 23 heated by the temperature control heating unit 26 is measured by the temperature measurement unit 25. Then, when the temperature of the pipe 23 becomes less than the lower limit of a certain temperature range, the operation of the temperature control heating unit 26 is controlled so that the temperature of the pipe 23 becomes high. Further, when the temperature of the pipe 23 exceeds the upper limit of a certain temperature range, the operation of the temperature control heating unit 26 is controlled so that the temperature of the pipe 23 becomes low.

In addition, in order to stabilize the temperature of the pipe 23, a heat insulating sheet or a heat insulating sheet may be wrapped around the pipe 23.

Further, the temperature control heating unit 26 can apply a known configuration used for temperature control of piping. For example, a configuration in which the pipe 23 is heated by a heater such as an electric heater, or a configuration in which a heat medium such as steam or hot oil is circulated around the pipe 23 can be mentioned.

Specifically, it is preferable that the pipe 23 has a jacket attached to the entire outer periphery thereof. A circulation line of the heat medium is connected to the jacket, and is connected to the temperature control mechanism of the heat medium oil or steam via this circulation line. The temperature control mechanism can control the temperature of the heat medium oil or steam based on the temperature of the pipe 23 measured by the temperature measuring unit 25 provided in the pipe 23. The temperature-controlled heat medium oil or steam circulates in the jacket, so that the pipe 23 can be controlled to a constant temperature. The temperature of the heat medium oil or steam that heats the pipe 23 is preferably controlled by PI control or PID control.

Further, the temperature control of the pipe 23 can also be performed by a temperature control type aluminum cast heater in which a sheathed heater is cast in the aluminum ingot and a temperature control mechanism for controlling the temperature of the heater is integrated. .. Similar to the heat medium oil heater, even if it is heated by an aluminum cast heater, the pipe 23 can be controlled to a constant temperature due to the good heat conduction of aluminum.

Further, in the temperature control mechanism 24, the temperature of the pipe 23 is within the range of the glass transition temperature of the molten resin P + 50 ° C. to the glass transition temperature of the molten resin P + 160 ° C., preferably the glass transition temperature + 70 ° C. to the glass transition temperature + 140 ° C. The temperature is controlled so as to be within the range of, more preferably within the range of the glass transition temperature + 90 ° C. to the glass transition temperature + 120 ° C. By controlling the temperature of the pipe 23 in such a temperature range, the molten resin P passing through the pipe 23 is surely in a molten state, and the molten resin P can be smoothly isolated from the space A to the space B. ..

<Raw material for effervescent thermoplastic resin particles>
In the present embodiment, various additives can be added as needed in addition to the thermoplastic resin and the foaming agent as raw materials for producing the foamable thermoplastic resin particles. For example, flame retardants, heat stabilizers, radical generators, processing aids, weathering stabilizers, nucleating agents, foaming aids, antistatic agents, radiant heat transfer inhibitors, colorants and the like can be mentioned. .. These additives may be used alone or in combination of two or more.

Further, the thermoplastic resin used in the present embodiment can contain a known thermoplastic resin, for example, polystyrene (PS), styrene-acrylonitrile copolymer (AS), styrene- (meth) acrylic acid. Polymer (heat resistant PS), styrene- (meth) acrylic acid ester copolymer, styrene-butadiene copolymer (HIPS), N-phenylmaleimide-styrene-maleic anhydride three-dimensional copolymer, and AS Polystyrene resin such as alloy (IP); vinyl resin such as polymethylmethacrylate, polyacrylonitrile resin, polyvinyl chloride resin; polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-propylene-butene ternary Polyolefin-based resins such as polymers and cycloolefin-based (co) polymers, and polyolefin-based resins that are rheologically controlled by introducing branched and crosslinked structures into these; nylon 6, nylon 66, nylon 11, nylon 12, MXD nylon. Polyamide-based resins such as: Polyethylene terephthalate, polybutylene terephthalate, polyarylate, polyester resins such as polycarbonate, aliphatic polyester resins such as polylactic acid; polyphenylene ether-based resin (PPE), modified polyphenylene ether-based resin (modified PPE) , Polyoxymethylene resin, polyphenylene sulfide resin, polyphenylene sulfide resin, aromatic polyether resin, polyether ether ketone resin and other engineering plastics. These may be used alone or in combination of two or more. Among these, a styrene-based resin is preferable because it is inexpensive and easy to foam-mold.

As the foaming agent used in the present embodiment, a known foaming agent can be used, but a hydrocarbon-based foaming agent is preferable. Hydrocarbons having 4 to 5 carbon atoms are more preferable from the viewpoint of easy high foaming, and examples thereof include normal butane, isobutane, normal pentane, isopentane, and cyclopentane. These may be used alone, or may be used in combination of two or more.

<Manufacturing method of effervescent thermoplastic resin particles>
The method for producing foamable thermoplastic resin particles according to the present embodiment includes an extrusion step of extruding a molten resin containing a thermoplastic resin through a die, and before the extrusion step, the molten resin is discharged to the outside by a diverter valve. The method is not particularly limited as long as it includes a discharge step and an isolation step of separating the molten resin discharged to the outside into a space different from the space for producing the resin particles in the molten state. For example, a manufacturing method using the manufacturing apparatus 100 described above can be mentioned. Hereinafter, a method for producing foamable thermoplastic resin particles using the production apparatus 100 will be described with reference to FIGS. 1 and 2.

First, in the manufacturing method according to the present embodiment, the thermoplastic resin is charged into the extruder 10 from the hopper 11 and melted at a resin temperature of, for example, 100 ° C. or higher and 300 ° C. or lower. From the viewpoint of suppressing decomposition of the thermoplastic resin, it is preferable to melt the thermoplastic resin at a resin temperature of 110 ° C. or higher and 250 ° C. or lower. Depending on the type and characteristics of the foamable thermoplastic resin particles to be produced, additives other than the above-mentioned thermoplastic resin may be added to the extruder 10. In this case, by charging the extruder 10 in which another additive is blended with the thermoplastic resin in advance, the additive can be added at the same time as the thermoplastic resin. Alternatively, the extruder 10 may be provided with an addition port different from the hopper 11 for charging the thermoplastic resin, and another additive may be charged into the extruder 10 from this addition port.

Further, when adopting a tandem type configuration using two extruders 10, it is preferable to adopt a configuration of a single-screw extruder-single-screw extruder and a twin-screw extruder-single-screw extruder, and it is preferable to adopt the upstream side. A twin-screw extruder-single-screw extruder configuration that employs a twin-screw extruder is more preferable. In this case, the supply of the raw material to the extruder 10 is stable, the foaming agent, the flame retardant, the flame retardant aid, and other additives are easily dispersed evenly, and the flame retardancy of the obtained thermoplastic resin in-mold foam molded product is easily dispersed. Is stable and highly expressed, and the flame retardancy level of each test piece cut out from one thermoplastic resin in-mold foam molded product tends to be stable.

Next, the foaming agent is added to the extruder 10 from the foaming agent supply pipe 12 by the high pressure pump 13.

After the molten resin P containing the thermoplastic resin and the foaming agent is melt-kneaded in the extruder 10 in this way, the molten resin P is extruded through the die 20 (extrusion step). In the manufacturing method according to the present embodiment, for example, the molten resin P is discharged to the outside by the divertor valve 22 (discharge step) before the extrusion step is actually carried out. In the discharge step, an extrusion operation by the extruder 10 is performed to perform melt kneading. Then, the divertor valve 22 is operated so that the second flow path 22b communicates with the upstream side flow path 21a, and the obtained molten resin P is discharged to the outside of the apparatus without being supplied to the downstream side flow path 21b side.

In the manufacturing method according to the present embodiment, an isolation step is carried out in which the molten resin P is isolated into a space B different from the space A in which the foamable thermoplastic resin particles are produced in the molten state. The pipe 23 is connected to the second flow path 22b of the divertor valve 22. Therefore, in the isolation step, the molten resin P discharged to the outside of the apparatus is isolated to a space B different from the space A in which the manufacturing apparatus 100 is operated via the pipe 23. In the isolation step, the molten resin P is isolated to another space B while the temperature of the pipe 23 is maintained within the range of the glass transition temperature of the molten resin P + 50 ° C. to the glass transition temperature of the molten resin P + 160 ° C. Is preferable.

Since the molten resin P, which is in a molten state in which flammable gas is likely to be generated, can be isolated to another space B without being exposed to the outside, it is possible to avoid the filling of the combustible gas in the space A in which the manufacturing apparatus 100 is operated. can do.

The discharge step and the isolation step are carried out, for example, until the physical properties or properties of the molten resin P and the temperature of each part of the manufacturing apparatus 100 are stabilized in a steady state. Further, the discharge step and the isolation step are carried out until the cutting defect and the dice hole blockage are resolved. Then, when the physical properties or properties of the molten resin P are stabilized in a steady state, or when the cutting defect or the blockage of the die hole is resolved, the molten resin P is extruded through the die 20 to be extruded.

More specifically, the temperature of each part of the manufacturing apparatus 100, the temperature or the pressure of the molten resin P, and the like are measured, and when the measured values are stabilized without fluctuation with time, the process shifts from the discharge process and the isolation process to the extrusion process. Further, after a predetermined time has elapsed after switching the formulation of the raw material, the process shifts from the discharge process and the isolation process to the extrusion process. Further, when it is determined that granulation is possible by cleaning the inside of the cutting chamber 4 or opening the die hole, the process shifts from the discharge process and the isolation process to the extrusion process.

In the extrusion step, first, the divertor valve 22 is operated to arrange the first flow path 22a between the upstream side flow path 21a and the downstream side flow path 21b, and supply the molten resin P to the resin flow path 20d side. .. Along with this, water is introduced into the cutting chamber 4 and the cutter 3 is rotated.

The temperature of the molten resin P immediately before being extruded from the die 20 is [glass transition temperature + 40 ° C.] or higher, [glass transition temperature + 100 ° C.] or lower, more preferably [glass] of the thermoplastic resin in a state containing no foaming agent. It is desirable that the transition temperature is + 50 ° C.] or higher and [glass transition temperature + 70 ° C.] or lower. At such a temperature, the die holes 20e are less likely to be clogged, and foamable thermoplastic resin particles having a desired particle shape can be easily obtained. Further, the foamable thermoplastic resin particles do not unintentionally foam, the viscosity of the molten resin P extruded from the die 20 becomes appropriate, and the molten resin P does not wind around the cutter 3. It is possible to produce stable effervescent thermoplastic resin particles.

[Embodiment 2]
The other embodiments of the present invention will be described below with reference to FIG. For convenience of explanation, the same reference numerals are given to the members having the same functions as the members described in the above-described embodiment, and the description thereof will be omitted. FIG. 4 is a diagram showing a schematic configuration of the foamable thermoplastic resin particle manufacturing apparatus 100A according to the present embodiment. In FIG. 4, in order to clarify the feature points of the manufacturing apparatus according to the present embodiment, the pipeline 5, the water supply pump 6, the water tank 7, the dehydration processing unit 8, and the container 9 are omitted.

The manufacturing apparatus 100A according to the present embodiment is mainly different from the first embodiment in that the mixing cooling unit 30 is arranged between the extruder 10A and the die 20. Further, the extruder 10A is provided with a hopper 11 for supplying raw materials, and is not provided with a foaming agent supply pipe 12. It is not excluded that the extruder 10A is provided with a foaming agent supply unit.

In the manufacturing apparatus 100A, the gear pump 14 is arranged on the downstream side of the extruder 10A, and the gear pump 16 is arranged on the upstream side of the mixing cooling unit 30. A continuous pipe 15 that relays the gear pump 14 and the gear pump 16 is arranged. The foaming agent supply pipe 12 and the high pressure pump 13 are provided in the continuous pipe 15. Therefore, in the manufacturing apparatus 100A, the molten resin is melt-kneaded by the extruder 10A, and then the foaming agent is supplied from the foaming agent supply pipe 12 when it is transferred to the continuous pipe 15 by the gear pump 14. ..

When the foaming agent is added in the continuous pipe 15 connected to the downstream side of the extruder 10A as in the present embodiment, the added foaming agent does not backflow (gas out) from the hopper 11 of the extruder 10A. It is stably contained in the thermoplastic resin. As a result, the variation in the foaming agent content contained in each of the obtained foamable thermoplastic resin particles is reduced.

Then, the molten resin to which the foaming agent is supplied is transferred to the mixing / cooling unit 30 by the gear pump 16. The mixed cooling unit 30 has a piping configuration in which a static mixer 31, a gear pump 32, a static cooler 33, and a gear pump 34 are arranged in this order from the upstream side to the downstream side. The static mixer 31 is useful for uniformly mixing the molten resin. Further, the static cooler 33 is useful for cooling the molten resin to a predetermined temperature. In the mixed cooling unit 30, the molten resin is mixed and cooled by the mixing function of the static mixer 31 and the cooling function of the static cooler 33.

Further, the gear pump is a useful member for maintaining the pressure of the flow of the molten resin or appropriately boosting the pressure. Since the manufacturing apparatus 100A according to the present embodiment has the configuration in which the gear pumps 14, 16, 32, and 34 are provided in the flow path from the extruder 10A to the die 20, the pressure of the molten resin in the flow path is maintained. It is easy and a stable discharge amount can be realized.

In the manufacturing apparatus 100A according to the present embodiment, since the mixing cooling unit 30 is arranged between the extruder 10A and the die 20, the molten resin melt-mixed in the flow path from the extruder 10A to the die 20. Will be cooled.

Therefore, the resin temperature of the molten resin in the flow path between the extruder 10A and the die 20 is equal to or higher than the [glass transition temperature + 40 ° C.] of the thermoplastic resin in a state where the foaming agent is not contained, and [glass transition]. Temperature + 100 ° C.] or lower, more preferably [Glass transition temperature + 50 ° C.] or higher, [Glass transition temperature + 70 ° C.] or lower.

Further, in the mixed cooling unit 30, the static mixer 31 and the static cooler 33 may be provided separately or may be integrated. For example, a static mixer 31, a static cooler 33, or an integrated static mixer 31 and a static cooler 33 can be obtained from SULZER, FLUITEC, STAMIXCO, and the like. Gear pumps 14, 16, 32, and 34 are available from PSI-POLYMER SYSTEM, EXTRUSION AUXILIALY SERVICES, and the like. The continuous pipe 15 can be easily manufactured by providing or not providing an addition port for various additives, and also considering the operating temperature, pressure, etc., and if you contact the above-mentioned companies or the extruder manufacturer, , Available.

Further, in the configuration shown in FIG. 4, the mixed cooling unit 30 is configured to include a static mixer 31 and a static cooler 33. However, the configuration of the mixed cooling unit 30 is not particularly limited as long as it is possible to cool the molten resin while mixing it. For example, the mixing cooling unit 30 may be configured to include a single-screw extruder.

Further, in the configuration shown in FIG. 4, the upstream portion of the die holder 21 is connected to the downstream end portion of the gear pump 34, and the same operation as in the first embodiment is performed.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention.

The manufacturing apparatus according to the first aspect of the present invention is an apparatus for producing foamable thermoplastic resin particles, which comprises a die having a plurality of holes and extrudes and granulates a molten resin containing a thermoplastic resin and a foaming agent through the die. A switching valve that is connected to the upstream side of the die and switches the transfer of the molten resin to the die and the discharge to the outside is provided, and the molten resin discharged to the outside by the switching valve is in a molten state. It is a configuration in which a pipe is provided to isolate the space from the space in which the plastic is operated.

According to the above configuration, the molten resin discharged to the outside of the device by the switching valve can be isolated to another space in the molten state through the above pipe without being exposed to the outside. As described above, since the molten resin in a molten state in which flammable gas is likely to be generated can be isolated without being exposed to the outside, it is possible to avoid the filling of the flammable gas in the space in which the manufacturing apparatus is operated. Therefore, according to the above configuration, the foamable thermoplastic resin particles can be safely produced.

In the first aspect of the manufacturing apparatus according to the second aspect of the present invention, the piping may be configured to include a temperature control mechanism for controlling the temperature of the piping. As a result, the molten resin can be efficiently isolated in another space in the molten state.

In the manufacturing apparatus according to the third aspect of the present invention, in the first or second aspect, the temperature of the pipe may be in the range of the glass transition temperature of the molten resin + 50 ° C. to the glass transition temperature of the molten resin + 160 ° C. As a result, the molten resin can be reliably isolated in another space in the molten state.

The production method according to aspect 4 of the present invention is a method for producing foamable thermoplastic resin particles, which comprises an extrusion step of extruding a molten resin containing a foaming agent and a thermoplastic resin through a die, and is a method for producing foamable thermoplastic resin particles before the extrusion step. The configuration includes a discharge step of discharging the molten resin to the outside by a switching valve and an isolation step of separating the molten resin discharged to the outside into a space different from the space where the resin particles are manufactured in the molten state. be. Thereby, the foamable thermoplastic resin particles can be safely produced from the molten resin containing the thermoplastic resin and the foaming agent.

In the manufacturing method according to the fifth aspect of the present invention, in the isolation step, the molten resin may be isolated into the other space via a pipe in the isolation step.

In the manufacturing method according to the sixth aspect of the present invention, in the isolation step, the temperature of the pipe is maintained in the range of the glass transition temperature of the molten resin + 50 ° C. to the glass transition temperature of the molten resin + 160 ° C. in the isolation step. In this state, the molten resin may be isolated in the other space.

10, 10A Extruder 20 Die 22 Divertor valve (switching valve)
23 Piping 24 Temperature control mechanism 100, 100A Manufacturing equipment A Space (space for operating the equipment)
B Another space

Claims (6)

An apparatus for producing foamable thermoplastic resin particles, which comprises a die having a plurality of holes and extrudes and granulates a molten resin containing a thermoplastic resin and a foaming agent through the die.
It is connected to the upstream side of the die and is provided with a switching valve for switching the transfer of the molten resin to the die and the discharge to the outside.
The molten resin is discharged to the outside in a molten state by the switching valve, the expandable thermoplastic resin particles, characterized in that the space for operating the device are pipes is provided to isolate the other spaces manufacturing device. The apparatus for producing foamable thermoplastic resin particles according to claim 1, wherein the pipe includes a temperature control mechanism for controlling the temperature of the pipe. The apparatus for producing foamable thermoplastic resin particles according to claim 1 or 2, wherein the temperature of the pipe is in the range of the glass transition temperature of the molten resin + 50 ° C. to the glass transition temperature of the molten resin + 160 ° C. A method for producing foamable thermoplastic resin particles, which comprises an extrusion step of extruding a molten resin containing a foaming agent and a thermoplastic resin through a die.
Before the extrusion process, a discharge step of discharging the molten resin to the outside by a switching valve and a discharge step of discharging the molten resin to the outside.
The discharged molten resin to the outside in a molten state, method for producing expandable thermoplastic resin particles comprising a the isolation step to isolate to another space and space to produce the resin particles. The method for producing foamable thermoplastic resin particles according to claim 4, wherein in the isolation step, the molten resin is isolated into the other space via a pipe. In the isolation step, the molten resin is isolated into the other space while the temperature of the pipe is maintained within the range of the glass transition temperature of the molten resin + 50 ° C. to the glass transition temperature of the molten resin + 160 ° C. The method for producing foamable thermoplastic resin particles according to claim 5, wherein the foamable thermoplastic resin particles are produced.

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