WO2009104671A1 - Granulation die, granulator, and method for producing foamable thermoplastic resin particle - Google Patents

Abstract

A granulation die (1) used in a granulator (T) for performing granulation with use of underwater hot-cutting system comprises a resin discharge surface (13) provided in contact with a cooling medium, a plurality of resin channels (14, 14, ...) communicating with an extruder (2), nozzles (15, 15, ...) communicating with the resin channels (14) and opening to the resin discharge surface (13), and a plurality of cartridge heaters (17) and short heaters (18) provided near the resin discharge surface (13). The resin channels (14) are arranged along the circumference of a virtual circle on the resin discharge surface (13), and the cartridge heaters (17) and short heaters (18) are arranged on the opposite sides in the circumferential direction of circumference of the resin channel (14) so as to traverse the circumference while directing the longitudinal direction thereof toward the radial direction of the circumference. In this granulation die with use of hot-cutting method, clogging of nozzle can be prevented, and particles having uniform diameter can be efficiently produced.

Description

Granulation die, granulation apparatus, and method for producing expandable thermoplastic resin particles

The present invention relates to a granulation die for forming thermoplastic resin particles by a hot cut method, a granulating apparatus, and a method for producing foamable thermoplastic resin particles.
This application claims priority based on Japanese Patent Application No. 2008-39116 for which it applied to Japan on February 20, 2008, and uses the content here.

2. Description of the Related Art Conventionally, as an apparatus for molding thermoplastic resin pellets (referred to as a pelletizer), an extruder, a die attached to the tip of the extruder, and a cutter are configured. 2. Description of the Related Art Generally, an apparatus is known that extrudes a melt-kneaded resin material from a die and cuts it with a cutter to produce pellets of a desired size.

As a method for cutting a resin material extruded from a die nozzle, there is a hot cut method.
This hot-cut method is a method in which a high-temperature resin immediately after being pushed into the water stream is cut with a cutter by bringing it into contact with the water stream circulating through the tip end face of the die where a plurality of nozzles are open. Granulation by the hot cut method is advantageous in that the resin is cut in a state where the resin is not sufficiently cured, so that the resin is not powdered and spherical particles are obtained.

However, in the hot cut method, since the resin discharge surface of the die is in contact with the water flow, heat is taken away from the water flow side, and the inside of the die may be partially lowered to a temperature below the melting point of the resin. As a result, the nozzle is clogged and productivity is lowered. In addition, the clogging may cause unevenness in the particle size of the particles, which may deteriorate the quality. Furthermore, when clogging increases, the extrusion pressure of the resin from the die becomes abnormally high, and the pressure limit of the die may be exceeded, making extrusion impossible.

Conventionally, for example, techniques disclosed in Patent Documents 1 and 2 have been proposed as techniques for preventing clogging of nozzles in a granulation die used for granulation by a hot cut method.
Patent Document 1 discloses a granulating die in which a bar heater is disposed at the center position of a circularly arranged nozzle in the same direction as the resin flow path of the nozzle. By disposing the rod heater, the heater and each nozzle are equidistant, and each nozzle is heated uniformly. Therefore, clogging of the nozzle is less likely to occur, low pressure loss and start of extrusion in water are possible, and high quality pellets can be obtained.
Patent Document 2 discloses a structure in which a heat insulating material is provided on the surface of a die in a method for producing thermoplastic resin particles obtained by cutting molten resin extruded from a die with a rotary cutter into resin particles.
In addition, both patent documents 1 and 2 are granulated without containing a foaming agent.
JP-A-7-178726 JP-A-5-301218

However, the conventional techniques disclosed in Patent Documents 1 and 2 have the following problems.
That is, when mixing foaming agents in an extruder to obtain expandable resin particles, it is necessary to suppress foaming of the foaming agent-containing resin composition discharged from the die. Therefore, the water temperature of the circulating water (cooling water) into the cutting chamber (chamber) must be lower (30 to 40 ° C.) than that of non-foamed resin particles (80 to 90 ° C.). Further, since the melt viscosity of the resin is lowered by the foaming agent, it is difficult to perform granulation without contacting (pressing) the cutter blade to the die surface.
In the prior art disclosed in Patent Document 1, the rod heater is arranged so that the tip of the rod heater is close to the resin discharge surface of the die. However, the rod heater has a nichrome wire installed to the tip due to its structure. Because it is not possible, the heater tip does not generate heat. For this reason, when foaming resin particles are granulated, it is difficult to sufficiently heat the resin discharge surface at the tip end of the die that requires the most heating in this die structure, and clogging cannot be prevented.

In addition, the prior art disclosed in Patent Document 2 describes the production of simple resin pellets in which no foaming agent is mixed. On the other hand, as described above, when foaming thermoplastic resin particles are granulated, unlike the case of simple resin pellets, the temperature of the circulating water may be 40 ° C. or lower because it is necessary to suppress foaming of the particles. desirable. For this reason, the difference between the resin temperature and the circulating water temperature becomes large, and the heat removal from the die tip portion due to the water flow cannot be suppressed with the heat insulating material alone, and nozzle clogging is likely to occur. Further, as described above, in the production of expandable thermoplastic resin particles, since the resin is softened by the foaming agent, it is necessary to cut the discharged resin by contacting (pressing) the cutter surface with the die surface. In the die structure whose surface is covered with a heat insulating material as disclosed in Patent Document 2, the heat insulating material is worn by the cutter blade in a short time, and there is a problem in the durability of the die.

The present invention has been made in view of the above-described problems, and prevents granulation of nozzles in a granulation die by a hot cut method, and enables efficient production of particles having a uniform particle diameter. An object of the present invention is to provide a granulating apparatus and a method for producing expandable thermoplastic resin particles.

In order to achieve the above object, the granulation die according to the present invention employs the following configuration. That is, the granulation die includes a resin discharge surface provided in contact with the cooling medium, a plurality of resin flow paths communicating with the resin supply device, and a nozzle communicating with the resin flow path and opening on the resin discharge surface. And a plurality of cartridge heaters provided in the vicinity of the resin discharge surface. Further, the resin flow path is arranged along the circumference of the virtual circle on the resin discharge surface, and the cartridge heater is arranged on both sides of the circumference of the circumference of the resin flow path, and the longitudinal direction is the radial direction of the circumference. It is arranged across the circumference toward

Also, in the granulation die according to the present invention, it is preferable that eight or more cartridge heaters are provided, and the respective central angles are 45 ° or less.

In the granulation die according to the present invention, the cartridge heater is preferably provided at a position 10 to 50 mm from the resin discharge surface.

Further, in the granulation die according to the present invention, it is preferable that the cross-sectional shape of the resin flow path has a straight portion on its outer periphery, and the straight portion is arranged substantially parallel to the longitudinal direction of the cartridge heater.

In the granulation die according to the present invention, it is preferable that a plurality of nozzles are provided in the resin flow path along the cross-sectional shape.

In the granulation die according to the present invention, temperature sensors are provided at least on the upstream side and the downstream side in the water flow direction of the cooling medium, and the cartridge heaters are individually controlled to be turned on and off based on the temperature measured by the temperature sensor. It is preferable to be configured.

Moreover, the granulation apparatus according to the present invention contains the granulation die described above, a resin supply device with the granulation die attached to the tip, and a cutter for cutting the resin discharged from the nozzle of the granulation die. And a chamber in which a cooling medium is brought into contact with the resin discharge surface of the granulation die.

In addition, the method for producing expandable thermoplastic resin particles according to the present invention includes a step of supplying a thermoplastic resin to a resin supply apparatus equipped with the above-described granulation die and melt-kneading the thermoplastic resin, and a thermoplastic resin for granulation. A process of injecting a foaming agent into the thermoplastic resin while moving it toward the die to form a foaming agent-containing resin, and a foaming agent-containing resin discharged from the nozzle of the granulating die are cut in a cooling medium by a cutter. And obtaining a foamable thermoplastic resin particle.

Further, in the method for producing expandable thermoplastic resin particles according to the present invention, at least the upstream and downstream die temperatures in the water flow direction of the cooling medium are measured, and each cartridge heater is adjusted so that the respective measured values are equal. It is preferable to perform on / off control individually.

Further, the method for producing the expanded thermoplastic resin particles according to the present invention includes a step of supplying a thermoplastic resin to a resin supply apparatus having the above-mentioned granulation die attached thereto, and melt-kneading the thermoplastic resin, and a thermoplastic resin into the granulation die. The process of forming a foaming agent-containing resin by injecting a foaming agent into the thermoplastic resin while moving toward the surface of the thermoplastic resin, and cutting the foaming agent-containing resin discharged from the nozzle of the granulation die in a cooling medium with a cutter A step of obtaining expandable thermoplastic resin particles, and a step of prefoaming the expandable thermoplastic resin particles to obtain the expanded thermoplastic resin particles.

Further, the method for producing a thermoplastic resin foam molded article according to the present invention comprises a step of supplying a thermoplastic resin to a resin supply apparatus equipped with the above-mentioned granulation die and melt-kneading the thermoplastic resin, and a thermoplastic resin for granulation. The process of forming a foaming agent-containing resin by injecting a foaming agent into a thermoplastic resin while moving toward the die, and the foaming agent-containing resin discharged from the nozzle of the granulation die in a cooling medium To obtain foamable thermoplastic resin particles, to heat foamable thermoplastic resin particles to pre-foam and obtain thermoplastic resin foam particles, and to mold thermoplastic resin foam particles in-mold and thermoplastic And obtaining a resin foam molded body.

The expandable thermoplastic resin particles according to the present invention are expandable thermoplastic resin particles obtained by the above-described method for producing expandable thermoplastic resin particles.

The thermoplastic resin expanded particles according to the present invention are thermoplastic resin expanded particles obtained by pre-expanding the above-described expandable thermoplastic resin particles.

Further, the thermoplastic resin foam molded article according to the present invention is a thermoplastic resin foam molded article obtained by in-mold foam molding of the thermoplastic resin foam particles described above.

According to the granulating die, the granulating apparatus, and the foaming thermoplastic resin particle manufacturing method of the present invention, the resin flow path and the nozzle are heated while being sandwiched from both sides by the cartridge heater. Therefore, only one side of the resin flow path is not heated, and it can be heated evenly from both sides at equal distances. As a result, nozzle clogging can be suppressed, reduction in production efficiency due to clogging can be improved, and high-quality particles having a uniform particle diameter can be produced.

It is a block diagram of the granulation apparatus by embodiment of this invention. It is a sectional side view which shows schematic structure of the dice | dies for granulation by embodiment of this invention. It is a side view which shows the resin discharge surface of the die main body of FIG. It is a figure which shows an example of the arrangement | positioning state of a nozzle. It is a figure which shows an example of the arrangement state of the nozzle by the modification of this Embodiment, Comprising: It is a figure corresponding to FIG. 6 is a cross-sectional view of a die used in Comparative Example 1. FIG. It is a side view which shows the resin discharge surface of the die | dye used in the comparative example 1. FIG. 6 is a cross-sectional view of a die used in Comparative Example 2. FIG. It is a side view which shows the resin discharge surface of the die | dye used in the comparative example 2. FIG. 6 is a cross-sectional view of a die used in Comparative Example 3. FIG. It is a side view which shows the resin discharge surface of the die | dye used in the comparative example 3.

Explanation of symbols

1 Die for granulation 2 Extruder (resin feeding device) 3 Cutter 4 Chamber 6 Foaming agent-containing resin 10 Die body 11 Die holder 13 Resin discharge surface 14, 14A Resin flow path 14a, 14b Slope (straight portion) 15 Nozzle 16 Insulation 17 Cartridge heater 18 Short heater 19 Temperature detector L Heater depth (position of cartridge heater from resin discharge surface) T granulator

Hereinafter, a granulating die, a granulating apparatus, and a method for producing foamable thermoplastic resin particles according to an embodiment of the present invention will be described with reference to FIGS.
1 is a configuration diagram of a granulating apparatus according to an embodiment of the present invention, FIG. 2 is a side sectional view showing a schematic configuration of a granulating die according to an embodiment of the present invention, and FIG. 3 is a resin of the die body of FIG. FIG. 4 is a side view showing the discharge surface, and FIG.

As shown in FIGS. 1 and 2, the granulating apparatus T according to the present embodiment is a granulating apparatus that performs granulation by an underwater hot cut method, and employs the granulating die 1 according to the embodiment of the present invention. Is.
The granulating apparatus T includes an extruder 2 (resin feeding apparatus) having a granulating die 1 attached to the tip thereof, and a resin (in this embodiment, containing a foaming agent) discharged from the nozzle 15 of the granulating die 1. The cutter 3 for cutting the resin 20) is accommodated, and the chamber 4 for bringing the water flow into contact with the resin discharge surface 13 of the granulation die 1 is provided. A pipe 5 for flowing circulating water is connected to the chamber 4, and one end (upstream side of the chamber 4) of the pipe 5 is connected to a water tank 7 via a water pump 6. The other end (downstream side of the chamber 4) of the pipe 5 is provided with a dehydration processing unit 8 that separates foamed thermoplastic resin particles from the circulating water and dehydrates and dries them. The expandable thermoplastic resin particles separated by the dehydration processing unit 8 and dehydrated and dried are sent to the container 9. Reference numeral 21 is a hopper, 22 is a blowing agent supply port, and 23 is a high-pressure pump.
In the granulation apparatus T and the granulation die 1, the side from which the resin is discharged is referred to as “front” and “front end”, and the opposite side is defined as “rear” and “rear end” in the following description. Use.

As shown in FIGS. 2 and 3, the granulation die 1 includes a die body 10 and a die holder 11 fixed to the tip side (right side in the drawing) of the extruder 2, and the die body 10 is the die holder 11. It is being fixed to the front end side with a plurality of bolts 12, 12,.
The die holder 11 is provided in communication with the cylinder of the extruder 2, and a rear end side flow path 11 a and a front end side flow path 11 b are formed in that order from the rear end side toward the front end side. The die main body 10 is formed with a conical convex portion 10a that protrudes rearward at the central portion of the rear end surface, and the die main body 10 and the die holder 11 are connected to each other in the front end side flow passage 11b of the die holder 11. The conical convex part 10a is inserted with a predetermined gap. That is, the foaming agent-containing resin 20 that has passed through the rear end side flow passage 11a of the die holder 11 flows along the circumferential surface of the conical convex portion 10a in the front end side flow passage 11a, and a plurality of openings that are opened on the rear end face of the die body 10 are opened. It flows into the resin flow paths 14, 14,.

The die main body 10 has a resin discharge surface 13 that comes into contact with the water flow at its front end surface, and a plurality of resin flow paths 14 for transferring the foaming agent-containing resin 20 extruded from the extruder 2 toward the resin discharge surface 13; , And a plurality of nozzles 15, 15,... That are provided at the tips of the plurality of resin flow paths 14, 14,. Schematic configuration including a material 16, a cartridge heater 17 for heating the resin discharge surface 13 and the resin flow path 14 at a position closer to the extruder 2 than the resin discharge surface 13, and a short heater 18 for heating the die body 10. Has been.
The cartridge heater 17 and the short heater 18 can be appropriately selected and used from conventionally known cartridge heaters according to the size and shape of the die body 10. That is, as the cartridge heater 17 and the short heater 18, for example, a heating wire (nichrome wire) wound around a rod-shaped ceramic is inserted into a pipe (heat-resistant stainless steel), and a gap between the heating wire and the pipe is made high in heat conductivity and high. A bar heater having a high power density and encapsulated with a material having excellent insulating properties (MgO) can be used.
The cartridge heater 17 and the short heater 18 may be a cartridge heater with two lead wires on one side or a cartridge heater (seeds heater) with one lead wire on each side, but two lead wires on one side. A cartridge heater is preferred because it has a higher power density.

A heat insulating material 16 having a circular cross section is disposed at the center of the resin discharge surface 13 of the die body 10, and discharge ports of a plurality of nozzles 15, 15,... Are provided along concentric circles outside the heat insulating material 16 in the radial direction. ing. And the center part of the resin discharge surface 13 in which the heat insulating material 16 and the nozzles 15, 15,... Are arranged is in contact with water inside the chamber 4.

The resin flow paths 14, 14,... Have a circular cross section, extend in a direction orthogonal to the resin discharge surface 13, and have a circumference centered on the central axis of the die body 10 (on the resin discharge surface 13 Along the circumference of the virtual circle in FIG. In this embodiment, eight resin flow paths 14, 14,... Are provided, and the central angle between the resin flow paths 14, 14 adjacent in the circumferential direction of the circumference is 45 °. As described above, each resin flow path 14 communicates with the front end side flow path 11 b of the die holder 11.

The nozzles 15, 15,... Are arranged at predetermined intervals along the circumference of a virtual circle on the resin discharge surface 13. As shown in FIG. 4, specifically, one nozzle 15 is a nozzle unit in which a plurality of single nozzles 15a, 15b, 15c,... Then, this is called “nozzle”). As the arrangement method of each single nozzle 15a, 15b, 15c,..., For example, a method in which a large number of small nozzles are arranged on a plurality of small circles can be adopted. However, the arrangement is not limited to such an arrangement form.

The heat insulating material 16 is provided on the resin discharge surface 13 on the inner side of the circumference where the plurality of nozzles 15, 15,... Are arranged, so that the heat of the die main body 10 does not escape to the water in the chamber 4. 10 temperature drop is suppressed. As the heat insulating material 16, it is preferable to use a heat insulating material having water resistance and a structure having a high surface hardness. For example, a heat insulating material excellent in heat resistance and heat insulating performance that does not cause deformation or the like even when in contact with the high-temperature die body 10 is disposed, and this is covered with a waterproof resin such as a fluororesin excellent in heat insulating performance, On the resin discharge surface 13 side, a laminated heat insulating material 16 in which materials having high surface hardness such as stainless steel and ceramics are sequentially laminated can be used.

Each of the cartridge heater 17 and the short heater 18 is a rod heater, and the cartridge heater 17 is positioned closer to the resin discharge surface 13 than the short heater 18 in the direction of the rear end of the granulation die 1.
The cartridge heaters 17, 17,... Are disposed on both sides of the circumferential direction of the resin flow path 14, and are disposed in a state of crossing the circumference with the longitudinal direction thereof directed in the radial direction of the circumference. In the vicinity of the discharge surface 13, the resin discharge surface 13, the nozzle 15, and the resin flow path 14 are heated. In this embodiment, eight cartridge heaters 17, 17,... Are provided in the circumferential direction with a predetermined center angle (here, an angle of 45 °).
That is, the individual nozzles 15 are arranged so as to be sandwiched by the two cartridge heaters 17 and 17 from the circumferential direction of the circumference.

The cartridge heater 17 is provided in the vicinity of the resin discharge surface 13, that is, within a predetermined heater depth range from the resin discharge surface 13 toward the extruder 2 side. Here, the heater depth is the distance from the resin discharge surface 13 to the center of the surface heating cartridge heater 17 (L in FIG. 2), and indicates the position of the cartridge heater 17 from the resin discharge surface 13. ing. The heater depth is within a range that does not hinder the processing surface and durability of the die, and a smaller distance is preferable because the effect of suppressing nozzle clogging is increased. That is, the heater depth is preferably in the range of 10 to 50 mm. If it is less than 10 mm, there is a possibility that the processed surface of the die and the durability may be hindered, and if it exceeds 50 mm, the nozzle clogging suppression effect may be reduced. A more preferable range is 15 to 30 mm.

Furthermore, it is preferable that the diameter of the cartridge heater 17 is small as long as the heat generation capacity can be secured because the cross-sectional area of the resin flow path can be increased and the number of nozzles can be increased. That is, the diameter of the cartridge heater 17 is preferably 15 mm or less, but if it is less than 10 mm, the required heat generation capacity cannot be secured and the heater becomes expensive, and the diameter is preferably 10 mm to 15 mm, more preferably 10 mm to 12 mm.
The length of the cartridge heater 17 extends from the position extending in the radial direction of the die body 10 to the center side from the arranged nozzle 15 (that is, the position where at least the tip of the cartridge heater 17 is at the center side from the nozzle 15). It is a position up to substantially the outer periphery of the die body 10.

The short heaters 18, 18,... Are arranged on the rear side with a predetermined interval with respect to each cartridge heater 17, the same number (eight) as the number of cartridge heaters 17 is arranged, and the rear end side of the resin flow path 14 is heated. It has a function to do. The short heater 18 is shorter than the cartridge heater 17.

Also, the die body 10 is provided with temperature measuring elements 19 (19A, 19B, 19C, 19D) (temperature sensors) such as thermocouples at four positions on the top, bottom, left and right at a position close to the resin discharge surface 13. That is, the cartridge heaters 17 are individually controlled to be turned on / off based on the measured temperatures of the temperature measuring elements 19 so that the temperature of the die body 10 can be adjusted. Further, the installation position of the temperature measuring element 19 is preferably behind the resin discharge surface 13 and ahead of the cartridge heater 17. The installation location is not limited to four locations on the top, bottom, left, and right, and may be two locations on the top and bottom. Further, it is desirable to provide another temperature measuring element 19 ′ (see FIG. 2) near the short heater 18 for temperature control of the short heater 18.

Next, a method for producing expandable thermoplastic resin particles, thermoplastic resin expanded particles, and a thermoplastic resin foam molded article using the granulating apparatus T to which the above-described granulation die 1 is attached will be described.
The extruder 2 (resin supply device) used in the granulating apparatus T shown in FIG. 1 can be appropriately selected and used according to the type of resin to be granulated from various conventionally known extruders, for example, using a screw. Either an extruder or an extruder that does not use a screw can be used. Examples of the extruder using a screw include a single-screw extruder, a multi-screw extruder, a vent-type extruder, and a tandem extruder. Examples of the extruder that does not use a screw include a plunger type extruder and a gear pump type extruder. Moreover, any extruder can use a static mixer. Among these extruders, an extruder using a screw is preferable from the viewpoint of productivity. Moreover, the chamber 4 which accommodated the cutter 3 can also use the conventionally well-known thing used in the hot cut method.

In the present invention, the type of thermoplastic resin is not limited. For example, a polystyrene resin, a polyethylene resin, a polypropylene resin, a polyester resin, a vinyl chloride resin, an ABS resin, an AS resin, or the like can be used alone or in combination. Can be used. Furthermore, it is possible to use a recovered resin of a thermoplastic resin obtained after being used once as a resin product. In particular, polystyrene resins such as polystyrene (GPPS) and high impact polystyrene (HIPS) are preferably used.
Examples of polystyrene resins include homopolymers of styrene monomers such as styrene, α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, bromostyrene, and copolymers thereof. A polystyrene-based resin containing 50% by mass or more of styrene is preferable, and polystyrene is more preferable.
Further, the polystyrene resin may be a copolymer of the styrene monomer and a vinyl monomer copolymerizable with the styrene monomer, the main component of which is the styrene monomer. As, for example, alkyl (meth) acrylate such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cetyl (meth) acrylate, (meth) acrylonitrile, dimethyl maleate, dimethyl fumarate, diethyl In addition to fumarate and ethyl fumarate, bifunctional monomers such as divinylbenzene and alkylene glycol dimethacrylate are exemplified.
If a polystyrene resin is the main component, other resins may be added. Examples of the resin to be added include polybutadiene, styrene-butadiene copolymer to improve the impact resistance of the foamed molded article. A rubber-modified polystyrene resin to which a diene rubber-like polymer such as a polymer, ethylene-propylene-nonconjugated diene three-dimensional copolymer is added, so-called high-impact polystyrene is exemplified. Alternatively, a polyethylene resin, a polypropylene resin, an acrylic resin, an acrylonitrile-styrene copolymer, an acrylonitrile-butadiene-styrene copolymer, and the like can be given.
In the expandable thermoplastic resin particles of the present invention, the expandable polystyrene resin particles using a polystyrene resin as the thermoplastic resin are commercially available ordinary polystyrene resins, suspensions In addition to the use of polystyrene resins that are not recycled materials (hereinafter referred to as virgin polystyrene), such as polystyrene resins newly produced by polymerization methods, etc., the used polystyrene resin foam moldings can be reprocessed. The recycled material obtained can be used. As this recycled material, used polystyrene-based resin foam moldings, for example, fish boxes, household appliance cushioning materials, food packaging trays, etc., are collected and recycled using the limonene dissolution method or heating volume reduction method. Can do. Recyclable raw materials that can be used include home appliances (eg, TVs, refrigerators, washing machines, air conditioners) and office work, in addition to those obtained by reprocessing used polystyrene-based resin foam moldings. A non-foamed polystyrene resin molded product that has been separated and collected from an industrial machine (for example, a copying machine, a facsimile machine, a printer, etc.), pulverized, melt-kneaded, and repelletized can be used.

As shown in FIG. 1 and FIG. 2, when producing expandable thermoplastic resin particles using the granulator T described above, the thermoplastic resin is placed in an extruder 2 having a granulation die 1 attached to the tip. Is supplied from the hopper 21 and melted and kneaded. Next, while moving the thermoplastic resin toward the granulation die 1, the foaming agent is pressed into the thermoplastic resin from the foaming agent supply port 22 by the high-pressure pump 23, and the foaming agent and the thermoplastic resin are mixed. Thus, the foaming agent-containing resin 20 is formed.
The foaming agent-containing resin 20 is sent from the tip of the extruder 2 through the die holder 11 to the resin flow path 14 of the die body 10 of the granulating die 1. The foaming agent-containing resin 20 sent through the resin flow path 14 is discharged from each nozzle 15 of the die body 10 and immediately cut by the rotary blade of the cutter 3 in the water flow (in the cooling medium) of the chamber 4.

Thus, the foaming agent-containing resin 20 cut into particles in the chamber 4 becomes substantially spherical foaming thermoplastic resin particles. The foamable thermoplastic resin particles are transported in the pipeline 5 according to the water flow and reach the dehydration processing unit 8 where the foamable thermoplastic resin particles are separated from the circulating water, dehydrated and dried, and separated water. Is sent to the water tank 7. The foamable thermoplastic resin particles separated by the dehydration processing unit 8, dehydrated and dried are sent to the container 9 and accommodated in the container.

In addition, although the said foaming agent is not limited, For example, normal pentane, isopentane, cyclopentane, cyclopentadiene etc. can be used individually or in mixture of 2 or more types. Moreover, normal butane, isobutane, propane, etc. can also be mixed and used for the said pentane as a main component. In particular, pentanes are preferably used because they tend to suppress foaming of particles when discharged from a nozzle into a water stream.

The foamable thermoplastic resin particles mean resin particles formed into a granular shape, preferably a small spherical shape, by adding a foaming agent to a thermoplastic resin. The foamable thermoplastic resin particles are heated in a free space to be pre-foamed. The pre-foamed particles are placed in a cavity of a mold having a cavity having a desired shape, and the pre-foamed particles are melted by steam heating. After being attached, it can be used for producing a foamed resin molded article having a desired shape by releasing the mold.

Next, a method for adjusting the temperature of the granulation die 1 described above will be described.
As shown in FIG. 3, in the temperature adjusting method of the granulation die 1, two die bodies 10 corresponding to the temperature measuring bodies 19 </ b> A, 19 </ b> B, 19 </ b> C, 19 </ b> D provided on the top, bottom, left and right in the vicinity of the resin discharge surface 13 are used. The die body 10 is controlled at a predetermined temperature by dividing into four areas and performing temperature adjustment for individually turning on and off the cartridge heaters 17 in the areas so that the measured values measured by the temperature measuring elements 19 are equal. Can be held constant. Here, the cartridge heaters in the area are the two cartridge heaters 17 and 17 that are close to the temperature measuring body 19 in the case of four areas.
When the die body 10 is divided into two areas, for example, when the measured temperature of the temperature measuring body 19B located on the upstream side of the cooling water is lower than a predetermined temperature set in advance, the cartridge located on the upstream side Four heaters 17 are turned on to raise the temperature by heating. Alternatively, if the measured temperature of the temperature measuring element 19A located on the downstream side is higher than a predetermined temperature set in advance, four of the cartridge heaters 17 located on the downstream side are turned off to cancel the heating state and Control to lower.
By performing such temperature adjustment, it is possible to reduce a temperature difference caused by contact of circulating water by rotation of the cutter 3 in the chamber 4, and the temperature becomes uniform in the die body 10 (resin discharge surface 13). , Particles with a more uniform particle size can be formed.

In the granulating die, the granulating device, and the foaming thermoplastic resin particle manufacturing method according to the present embodiment described above, the resin flow path 14 and the nozzle 15 are heated while being sandwiched from both sides by the cartridge heater 17. . Therefore, only one side of the resin flow path is not heated, it can be heated evenly from both sides, and clogging of the nozzle 15 can be suppressed. As a result, it is possible to improve the reduction in production efficiency due to clogging and to produce high quality particles having a uniform particle size.

Next, modifications of the embodiment of the present invention will be described with reference to the drawings. However, the same or similar members and parts as those of the above-described embodiment are denoted by the same reference numerals, and the description is omitted. A configuration different from the form will be described.
FIG. 5 is a diagram illustrating a nozzle arrangement state according to a modification of the present embodiment, and corresponds to FIG.
The resin flow path 14A according to the modification shown in FIG. 5 has a trapezoidal cross section, and a nozzle 15 in which a plurality of single nozzles 15a, 15b, 15c,... Are arbitrarily arranged within the trapezoidal range is provided. It has been. The slopes 14 a and 14 b (straight line portions) that form the outline of the resin flow path 14 </ b> A are arranged substantially parallel to the longitudinal direction of the cartridge heater 17. In this modification, the slopes 14a and 14b of the resin flow path 14A having a trapezoidal cross section are equidistant from the cartridge heater 17, so that the area heated evenly by the cartridge heater 17 increases, and the circular cross section Compared with the resin flow path, the nozzle is heated more uniformly, and the clogging of the nozzle can be further reduced.

Examples In order to support the effects of the granulation die, the granulator, and the method for producing foamable thermoplastic resin particles according to the present embodiment, examples will be described below.

[Example 1]
In Example 1, expandable polystyrene resin particles were produced by attaching the granulation die 1 shown in FIGS. 2 and 3 to the granulator T shown in FIG. However, the temperature of the dice 1 was adjusted by controlling on / off all the cartridge heaters 17 using only the temperature measuring element 19A.
A single-screw extruder having a diameter of 90 mm (L / D = 35) and a granulation die having the structure shown in FIG. 2, that is, an eye plate (nozzle having 15 nozzles having a diameter of 0.6 mm and a land length of 3.0 mm) 8 cartridge heaters (diameter 12 mm) are arranged on the circumference of the resin discharge surface, and the resin flow channels leading to the nozzle unit are sandwiched from both sides on the resin discharge surface side. A distance from the discharge surface (corresponding to the symbol L in FIG. 2) is 15 mm, arranged radially across the circumference, and attached with a die with a heat insulating material in the center of the surface, polystyrene resin (manufactured by Toyo Styrene Co., Ltd., (Product name “HRM10N”) 100 parts by mass and 0.3 parts by mass of finely powdered talc previously mixed uniformly by a tumbler mixer were fed into the extruder at a rate of 130 kg per hour. After the maximum temperature in the extruder is set to 220 ° C. and the resin is melted, 6 parts by weight of pentane (isopentane / normal pentane = 20/80 mixture) is added from the middle of the extruder as a foaming agent to 100 parts by weight of the resin. Press-fitted.
Then, while kneading the resin and the foaming agent in the extruder, while cooling so that the resin temperature at the tip of the extruder is 170 ° C., through the die held at 280 ° C. attached to the tip of the extruder, 30 A high-speed rotary cutter having 10 blades in the circumferential direction is closely attached to the die, cut at 3300 revolutions per minute, dehydrated and dried to form a spherical foam. Polystyrene resin particles were obtained. At this time, the discharge amount of the expandable styrene resin particles was 138 kg / h.
In Example 1, the pressure of the resin introduction part to the die at the first hour of extrusion was 17.0 MPa, the mass of 100 resin particles after drying was 0.0724 g, and the die opening rate was 80.2. % And good.
The pressure of the resin introduction part to the die 48 hours after the start of extrusion is 17.3 MPa, the mass of 100 grains is 0.0741 g, the die opening rate is 78.4%, and it can be stably extruded for 48 hours or more. I was able to confirm.
About expandable styrene resin particles collected at 48 hours of extrusion, pre-expanded particles having a bulk expansion ratio of 50 times (bulk density: 0.02 g / cm ³ ) were prepared by the method described later, and foamed using the pre-expanded particles. A foam molded article having a multiple of 50 times (density 0.02 g / cm ³ ) was produced. The obtained foamed molded product was visually observed to evaluate the filling property of the pre-expanded particles into the molding die.

<Die opening rate>
Opening ratio (opening ratio during extrusion of the discharge nozzle on the die surface) = number of openings / total number of nozzles of the die × 100 (%).
Discharge rate (kg / h) = total mass of all expandable particles cut out by a cutter per 1 h = number of apertures × number of cuts × 1 particle mass = number of apertures × number of cutter blades × number of cutter rotations × 1 particle mass.
Since the number of holes = discharge amount (kg / h) / [number of cutter blades × cutter rotation speed (rph) × 1 grain mass (kg / piece)], the hole area ratio can be calculated by the following equation.
Opening ratio (E) = number of openings / total number of discharge nozzles x 100 (%)
= [Q / (N × R × 60 × (M / 100) / 1000)] / H × 100 (%)
(In the formula, Q is the discharge amount (kg / h), N is the number of cutter blades, R is the number of revolutions of the cutter (rpm), M is 100 particles mass (g) (select any 100 particles from the expandable particles, (The value weighed with an electronic balance with a minimum scale of 0.0001 g was taken as 100 masses), and H represents the total number of nozzles in the die.)

<Evaluation criteria for hole area ratio>
The hole area ratio (E) was evaluated according to the following criteria (see Table 1 described later).
A: 50% ≦ E,
○: 40% ≦ E <50%,
Δ: 30% ≦ E <40%
X: E <30%.
<Manufacture of foam molding>
The expandable styrene resin particles obtained at 48 hours after extrusion as described above were left at 20 ° C. for 1 day. Thereafter, with respect to 100 parts by mass of expandable styrene resin particles, 0.1 parts by mass of zinc stearate, 0.05 parts by mass of hydroxystearic acid triglyceride, and 0.05 parts by mass of monoglyceride stearate were added and mixed to obtain resin particle surfaces. After coating, the mixture is put into a small batch type pre-foaming machine (internal volume 40L) and heated with water vapor with a blowing pressure of 0.05 MPa (gauge pressure) while stirring to give a bulk foaming factor of 50 times (bulk density). 0.02 g / cm ³ ) pre-expanded particles were prepared.
Subsequently, the pre-expanded particles obtained were aged at 23 ° C. for 1 day, and then a mold having an outer dimension of 300 × 400 × 100 mm (thickness 30 mm) and an inner partition portion of thickness 5 mm, 10 mm, and 25 mm. Was molded under the following molding conditions using an automatic molding machine (Sekisui Koki Seisakusho, ACE-3SP type) to which a foam was attached to obtain a foamed molded product having a foaming ratio of 50 times (density 0.02 g / cm ³ ).
Molding conditions (ACE-3SP QS molding mode)
Molding vapor pressure 0.08MPa (gauge pressure)
Mold heating 3 seconds One-side heating (pressure setting) 0.03 MPa (gauge pressure)
Reverse one heating 2 seconds Double-sided heating 12 seconds Water cooling 10 seconds Set extraction surface pressure 0.02 MPa
<Evaluation criteria for mold filling properties of pre-expanded particles>
The foamed molded product was visually observed, and the mold filling property was evaluated as follows.
(Double-circle): It fills up to the partition part 5mm thick.
○: Filling of the partition part with a thickness of 5 mm is sweet and excessive foam particles are observed, but the partition part is formed.
(Triangle | delta): The particle | grain defect | deletion by poor filling is seen in the partition part with thickness 5mm, and the partition part is not formed completely.
X: The partition part with a thickness of 5 mm is poorly filled, and no partition part is formed at all.
<Total mass of 100 particles>
In the expandable polystyrene resin particles, the total mass of 100 arbitrarily selected particles is preferably in the range of 0.02 to 0.09 g. If it exceeds 0.09 g, it is difficult to fill the details of the mold, and the moldable mold may be limited to a simple shape. If it is less than 0.02 g, the productivity of the particles may be inferior. A more preferable range is 0.04 to 0.06 g. For resins other than polystyrene-based resins, a value obtained by multiplying the above range by the specific gravity of the resin is a range of the total mass of 100 preferable particles.
<Method for measuring bulk expansion ratio of pre-expanded particles>
After sufficiently drying the pre-expanded particles in a graduated cylinder (eg 500 ml capacity) using a funnel, tap the bottom of the graduated cylinder until the volume of the pre-expanded particles is constant. Filled. The volume and mass of the pre-expanded particles at that time were measured and calculated by the following formula. The volume was read in units of 1 ml, and the mass was measured with an electronic balance having a minimum scale of 0.01 g. The resin specific gravity of the styrene resin was calculated as 1.0, and the bulk expansion factor was rounded off to the first decimal place.
Bulk expansion ratio (times) = volume of pre-expanded particles (ml) / mass of pre-expanded particles (g) × resin specific gravity <Measurement method of expansion ratio of foam molded article>
A test specimen for measurement (example 300 × 400 × 30 mm) was cut out from the foamed product that had been sufficiently dried, the dimensions and mass of the test specimen were measured, and the volume of the test specimen was calculated based on the measured dimensions. It was calculated by the following formula. The specific gravity of the styrene resin was 1.0.
Foaming factor (times) = test piece volume (cm ³ ) / test piece mass (g) × resin specific gravity

[Example 2]
In Example 2, the resin flow path communicating with the nozzle unit of the die used in Example 1 is expanded (increase in cross-sectional area), and the dice with the number of nozzles per nozzle unit increased from 15 to 25 are attached. Except that, spherical foamable styrene resin particles were obtained in the same manner as in Example 1 at a discharge rate of 138 kg / h.
In Example 2, the pressure of the resin introduction part to the die at the first hour after extrusion was 14.0 MPa, the mass of 100 resin particles after drying was 0.0465 g, and the die opening rate was 75.0. % And good.
The pressure of the resin introduction part to the die 48 hours after the start of extrusion is 14.0 MPa, the mass of 100 grains is 0.0465 g, the die opening rate is 75.0%, and can be stably extruded for 48 hours or more. I was able to confirm.
For the expandable styrene resin particles collected at 48 hours of extrusion, pre-expanded particles having a bulk expansion ratio of 50 times (bulk density 0.02 g / cm ³ ) were prepared in the same manner as in Example 1, and the pre-expanded particles were used. Thus, a foamed molded article having a foaming ratio of 50 times (density 0.02 g / cm ³ ) was produced. The obtained foamed molded product was visually observed to evaluate the filling property of the pre-expanded particles into the molding die.

[Example 3]
In Example 3, two dice temperature measuring sensors (19B (inflow side) and 19A (outflow side) arranged at the upper and lower positions of the temperature measuring element 19 shown in FIG. 3) are used as the dice used in Example 2. ) To divide the area into 4 heaters on the circulating water inflow side (lower side, reference numeral 4a side in FIG. 2) and 4 heaters on the circulating water outflow side (upper side, reference numeral 4b side in FIG. 2). Thus, spherical expandable styrene resin particles were obtained at a discharge rate of 138 kg / h in the same manner as in Example 2 except that the die was kept at 280 ° C.
In Example 3, the pressure of the resin introduction part to the die at the first hour after extrusion was 13.3 MPa, the mass of 100 resin particles after drying was 0.0425 g, and the die opening rate was 82. It was as good as 0%.
The pressure of the resin introduction part to the die 48 hours after the start of extrusion is 13.3 MPa, the mass of 100 grains is 0.0425 g, the die opening rate is 82.0%, and stable extrusion is possible for 48 hours or more. I was able to confirm.
For the expandable styrene resin particles collected at 48 hours of extrusion, pre-expanded particles having a bulk expansion ratio of 50 times (bulk density 0.02 g / cm ³ ) were prepared in the same manner as in Example 1, and the pre-expanded particles were used. Thus, a foamed molded article having a foaming ratio of 50 times (density 0.02 g / cm ³ ) was produced. The obtained foamed molded product was visually observed to evaluate the filling property of the pre-expanded particles into the molding die.

[Example 4]
In Example 4, a spherical foamable styrene resin with a discharge amount of 138 kg / h was used in the same manner as in Example 2 except that the die used in Example 2 was changed from 15 mm to 30 mm in heater depth. Particles were obtained.
In Example 4, the pressure of the resin introduction portion to the die at the first hour after extrusion was 16.1 MPa, the mass of 100 resin particles after drying was 0.0524 g, and the die opening rate was 66.5. % And good.
The pressure of the resin introduction part to the die 48 hours after the start of extrusion is 16.8 MPa, the mass of 100 grains is 0.0581 g, and the opening rate of the die is 60.0%, which can be stably extruded for 48 hours or more. I was able to confirm.
For the expandable styrene resin particles collected at 48 hours of extrusion, pre-expanded particles having a bulk expansion ratio of 50 times (bulk density 0.02 g / cm ³ ) were prepared in the same manner as in Example 1, and the pre-expanded particles were used. Thus, a foamed molded article having a foaming ratio of 50 times (density 0.02 g / cm ³ ) was produced. The obtained foamed molded product was visually observed to evaluate the filling property of the pre-expanded particles into the molding die.

[Example 5]
In Example 5, a spherical foamable styrene resin with a discharge amount of 138 kg / h was used in the same manner as in Example 2 except that the die used in Example 2 was changed from 15 mm to 45 mm in heater depth. Particles were obtained.
In this Example 5, the pressure of the resin introduction part to the die 1 hour after the extrusion was 16.9 MPa, the mass of 100 resin particles after drying was 0.0670 g, and the die opening rate was 52.0. % And good.
The pressure of the resin introduction part to the die 48 hours after the start of extrusion is 18.1 MPa, the mass of 100 grains is 0.0871 g, and the opening rate of the die is 40.0%, which can be stably extruded for 48 hours or more. I was able to confirm.
For the expandable styrene resin particles collected at 48 hours of extrusion, pre-expanded particles having a bulk expansion ratio of 50 times (bulk density 0.02 g / cm ³ ) were prepared in the same manner as in Example 1, and the pre-expanded particles were used. Thus, a foamed molded article having a foaming ratio of 50 times (density 0.02 g / cm ³ ) was produced. The obtained foamed molded product was visually observed to evaluate the filling property of the pre-expanded particles into the molding die.
[Example 6]
In Example 6, spherical expandable styrene resin particles were obtained at a discharge rate of 138 kg / h in the same manner as in Example 2 except that only isopentane was used as the foaming agent.
In Example 6, the pressure of the resin introduction part to the die at the first hour after extrusion was 15.1 MPa, the mass of 100 resin particles after drying was 0.0458 g, and the die opening rate was 76. It was as good as 1%.
The pressure of the resin introduction part to the die 48 hours after the start of extrusion is 15.0 MPa, the mass of 100 grains is 0.0461 g, and the opening rate of the die is 75.6%, which can be stably extruded for 48 hours or more. I was able to confirm.
For the expandable styrene resin particles collected at 48 hours of extrusion, pre-expanded particles having a bulk expansion ratio of 50 times (bulk density 0.02 g / cm ³ ) were prepared in the same manner as in Example 1, and the pre-expanded particles were used. Thus, a foamed molded article having a foaming ratio of 50 times (density 0.02 g / cm ³ ) was produced. The obtained foamed molded product was visually observed to evaluate the filling property of the pre-expanded particles into the molding die.

[Comparative Example 1]
6A is a cross-sectional view of a die used in Comparative Example 1, and FIG. 6B is a side view showing a resin discharge surface of the die.
In Comparative Example 1, a die 20 having a known structure shown in FIGS. 6A and 6B, that is, 16 nozzle units (symbol 15) having 15 nozzles having a diameter of 0.6 mm and a land length of 3.0 mm are arranged on the circumference. Spherical foaming with a discharge amount of 138 kg / h is performed in the same manner as in Example 1 except that the die is disposed on the resin discharge surface 13 side and is changed to a die having no cartridge heater (that is, only the short heater 18 is disposed). Styrene resin particles were obtained.
In Comparative Example 1, the pressure of the resin introduction portion into the die at the first hour after extrusion was as high as 21.7 MPa, the mass of 100 grains was 0.1322 g, and the opening rate of the die was 22.0%.
With the passage of time, a pressure increase in the resin introduction portion was observed, and the pressure limit value (25 MPa) of the die was reached 6 hours after the start of extrusion, so the extrusion was terminated in 6 hours.

[Comparative Example 2]
7A is a sectional view of a die used in Comparative Example 2, and FIG. 7B is a side view showing a resin discharge surface of the die.
In Comparative Example 2, a die 30 having the structure shown in FIGS. 7A and 7B, that is, four cartridge heaters 17, 17,... (Diameter 12 mm) on the resin discharge surface 13 side, and a nozzle unit at a heater depth of 15 mm. Spherical expandable styrene resin particles were discharged at a discharge rate of 138 kg / h in the same manner as in Example 1 except that they were arranged in a cross across the circumference of the line and changed to a die having a heat insulating material 16 attached to the center of the surface. Obtained.
In Comparative Example 2, the pressure of the resin introduction portion into the die at the first hour after extrusion was slightly high, 20.0 MPa, the mass of 100 grains was 0.1030 g, and the die opening rate was 28.2%. .
With the passage of time, an increase in pressure in the resin introduction portion was observed, and the pressure limit value (25 MPa) of the die was reached 10 hours after the start of extrusion, so the extrusion was terminated in 10 hours.

[Comparative Example 3]
8A is a cross-sectional view of a die used in Comparative Example 3, and FIG. 8B is a side view showing a resin discharge surface of the die.
In Comparative Example 3, a die 40 having a known structure shown in FIGS. 8A and 6B, that is, there is no heat insulating material, an oil flow path 41 is provided in the die, and high-temperature oil flows from the upper and lower dies 41a and 41a. Example 1 except that the dies are maintained at 280 ° C. by indirect heating using oil as a heat medium instead of dice having a structure that flows out to the left and right 41b, 41b through the central annular channel and returns to the oil heater. Similarly, spherical expandable styrene resin particles were obtained at a discharge rate of 138 kg / h.
In Comparative Example 3, the pressure of the resin introduction part to the die 1 hour after the start of extrusion was 18.0 MPa, the mass of 100 grains was 0.0907 g, and the opening rate of the die was 32.0%.
The pressure of the resin introduction part to the die 48 hours after the start of extrusion was 21.8 MPa, the mass of 100 grains was 0.0994 g, and the die opening rate was 29.2%.
For the expandable styrene resin particles collected at 48 hours of extrusion, pre-expanded particles having a bulk expansion ratio of 50 times (bulk density 0.02 g / cm ³ ) were prepared in the same manner as in Example 1, and the pre-expanded particles were used. Thus, a foamed molded article having a foaming ratio of 50 times (density 0.02 g / cm ³ ) was produced. The obtained foamed molded product was visually observed to evaluate the filling property of the pre-expanded particles into the molding die.

Table 1 summarizes the results of Examples 1 to 6 and Comparative Examples 1 to 3 described above.

From the results of Table 1, in Examples 1 to 6 according to the present invention, the die pressure at 1 hour from the start of granulation is 13.3 to 17.0 MPa, and the die pressure at 48 hours is 13.3 to 18 The pressure was lower than that of Comparative Examples 1 to 3, and continuous operation was possible. Also, the nozzle opening rate was 52% or more after 1 hour and 40% or more after 48 hours, and in Examples 1 to 3, and 6, 75% or more after 1 hour and 75% after 48 hours. As described above, it was confirmed that the open area ratio (E) hardly changed with time.
In Example 5 where the heater depth is 45 mm, the hole area ratio is lower than in Example 4 where the heater depth is 30 mm. Therefore, the heater depth is preferably 10 to 50 mm, and 15 to 30 mm. Is more preferable.

On the other hand, in Comparative Examples 1 and 2, the increase in the die pressure due to nozzle clogging was noticeable, and reached the upper limit of the die withstand pressure after about 6 to 10 hours of operation. The aperture ratio of the nozzle was already as low as 22.0 to 32.0% after 1 hour.
Compared with Examples 1 to 6, the comparative example 3 has a complicated structure of the die because the annular oil flow path is provided in the die, and requires an oil heater and a circulation pump. Installation costs are high due to the need for heat insulation. In addition, when the flow path is clogged or deteriorated due to deteriorated oil or foreign matter, the heating balance is lost and the temperature of the die cannot be maintained uniformly.

As described above, the embodiment of the granulation die, the granulation apparatus, and the method for producing the foamable thermoplastic resin particles according to the present invention has been described, but the present invention is not limited to the above embodiment, Changes can be made as appropriate without departing from the spirit of the invention.
For example, in the present embodiment, there are eight resin flow paths 14 and eight cartridge heaters 17 and eight short heaters 18 respectively, but the number is not limited to this number, and the size of the granulation die 1, The optimum quantity can be set according to conditions such as the molding amount of the thermoplastic resin particles. In short, it is only necessary that the cartridge heaters are arranged on both sides of the circumference of the resin flow path 14 in the circumferential direction.
And although the four temperature measuring elements 19 are set as this, it is not limited to this, For example, the two temperature measuring elements 19 may exist in the up-and-down position.
Further, the shape, size, and other configurations of the extruder 2, the cutter 3, the chamber 4, the die holder 11, the die body 10, and the like are not particularly limited and can be arbitrarily set. For example, although an extruder is employed as the resin supply device in the present embodiment, a static mixer, a gear pump, or the like can also be used.

According to the present invention, the granulation die, the granulation apparatus, and the foaming thermoplasticity capable of preventing the nozzle clogging in the granulation die by the hot cut method and efficiently producing particles having a uniform particle diameter. A method for producing resin particles can be provided.

Claims (14)

1. A resin discharge surface provided in contact with the cooling medium;
   A plurality of resin flow paths communicating with the resin supply device;
   A nozzle communicating with the resin flow path and opening in the resin discharge surface;
   A plurality of cartridge heaters provided in the vicinity of the resin discharge surface;
   With
   The resin flow path is disposed along the circumference of a virtual circle on the resin discharge surface,
   The cartridge heater is arranged on both sides of the circumference of the circumference of the resin flow path, and is arranged in a state where the longitudinal direction is directed to the radial direction of the circumference and across the circumference. dice.
2. Eight or more cartridge heaters are provided,
   The granulation die according to claim 1, wherein each central angle is 45 ° or less.
3. The granulation die according to claim 1, wherein the cartridge heater is provided at a position of 10 to 50 mm from the resin discharge surface.
4. The cross-sectional shape of the resin flow path has a linear portion on its outer shell,
   The granulation die according to claim 1, wherein the linear portion is disposed substantially parallel to a longitudinal direction of the cartridge heater.
5. The granulation die according to claim 1, wherein the resin flow path is provided with a plurality of nozzles along the cross-sectional shape thereof.
6. Temperature sensors are provided at least upstream and downstream in the water flow direction of the cooling medium,
   The granulation die according to claim 1, wherein the cartridge heater is individually controlled to be turned on / off based on a temperature measured by the temperature sensor.
7. A granulation die according to any one of claims 1 to 6,
   A resin supply device with the granulation die attached to the tip;
   A granulating apparatus comprising: a chamber that houses a cutter that cuts the resin discharged from the nozzle of the granulation die, and a chamber that contacts a cooling medium with the resin discharge surface of the granulation die.
8. Supplying a thermoplastic resin to a resin supply apparatus equipped with the granulation die according to any one of claims 1 to 6 and melt-kneading;
   A step of injecting a foaming agent into the thermoplastic resin while moving the thermoplastic resin toward the granulation die to form a foaming agent-containing resin;
   Cutting the foaming agent-containing resin discharged from the nozzle of the granulation die in a cooling medium with a cutter to obtain expandable thermoplastic resin particles;
   A process for producing expandable thermoplastic resin particles.
9. The foamable thermoplastic resin particles according to claim 8, wherein at least upstream and downstream die temperatures in the water flow direction of the cooling medium are measured, and each cartridge heater is individually controlled to be turned on and off so that the respective measured values are equal. Manufacturing method.
10. Supplying a thermoplastic resin to a resin supply apparatus equipped with the granulation die according to any one of claims 1 to 6 and melt-kneading;
    A step of injecting a foaming agent into the thermoplastic resin to form a foaming agent-containing resin while moving the thermoplastic resin toward the granulation die;
    Cutting the foaming agent-containing resin discharged from the nozzle of the granulation die in a cooling medium with a cutter to obtain expandable thermoplastic resin particles;
    Pre-foaming the foamable thermoplastic resin particles to obtain thermoplastic resin foam particles;
    A method for producing foamed thermoplastic resin particles.
11. Supplying a thermoplastic resin to a resin supply apparatus equipped with the granulation die according to any one of claims 1 to 6 and melt-kneading;
    A step of injecting a foaming agent into the thermoplastic resin to form a foaming agent-containing resin while moving the thermoplastic resin toward the granulation die;
    Cutting the foaming agent-containing resin discharged from the nozzle of the granulation die in a cooling medium with a cutter to obtain expandable thermoplastic resin particles;
    Heating the foamable thermoplastic resin particles and pre-foaming to obtain thermoplastic resin foam particles;
    A step of foam-molding the thermoplastic resin foam particles to obtain a thermoplastic resin foam-molded article;
    The manufacturing method of the thermoplastic resin foaming molding which has this.
12. Expandable thermoplastic resin particles obtained by the method for producing expandable thermoplastic resin particles according to claim 8.
13. Thermoplastic resin expanded particles obtained by pre-expanding the expandable thermoplastic resin particles according to claim 12.
14. A thermoplastic resin foam molded article obtained by in-mold foam molding of the thermoplastic resin foam particles according to claim 13.

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