JPH06155455A - Granulator of thermoplastic resin - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a hot-cut type granulating apparatus which is small in size and has a simple structure, in which resin particles do not adhere to each other. A jet nozzle for jetting cooling water in an inverted umbrella shape is attached upward below a rotary cutter, and a casing is attached to a die so as to include the rotary cutter and the jet nozzle inside. The inverted umbrella-shaped cooling water jetted from the jet nozzle passes near the edge of the rotary cutter, is then guided along the wall surface of the casing, and is discharged from the casing together with the cut resin particles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot-cut type thermoplastic resin granulating apparatus in which a thermoplastic resin is extruded from a die in a heat-melted state and cut and granulated by a cutter.

[0002]

2. Description of the Related Art As a thermoplastic resin granulating device, a molten resin is extruded from a large number of pores of a die attached to the tip of an extruder, and the extruded strand resin is cooled by passing it through a water tank. It has been conventionally known to solidify and cut with a pelletizer. However, this method has a drawback in that even if one of the strands is cut, the whole strand must be drawn again.

Further, Japanese Patent Publication No. 2-12165 and Japanese Patent Publication No. 2-18963 disclose a hot-cut type granulating apparatus for immediately cutting molten resin extruded from a mold without passing through a cooling water tank. There is a device.
In this device, a rotating multi-blade cutting tool consisting of a cutter holder and a cutter is surrounded by a granule receiving casing, and the granules that are cut by the cutting tool and are accelerated by centrifugal force are covered with a high-speed rotating cooling water film of uniform thickness. It is bounced off by the wall of the broken granule receiving casing, introduced into the cooling water flowing to the outlet while being rotated at the bottom of the granule receiving casing, conveyed and discharged.

[0004]

However, the hot-cut type granulating apparatus described in the above publication is provided with an annular passage around which a cooling water circulates around the granule receiving casing.
It is necessary to inject and supply cooling water under pressure to centrifugally accelerate in the circumferential direction, and further to connect the annular acceleration chamber to the annular passage and push out the synthetic resin in the circumferential direction slightly above the mold. Since it is necessary to eject the water curtain from the slit-shaped gap, the device becomes structurally complicated. Further, in order to uniformly eject the water curtain from the slit-shaped gap of the annular acceleration chamber, the annular passage around the granule receiving casing must be enlarged to some extent, and the device becomes large.

Further, according to the granulating apparatus described in the above publication, there is a certain amount of space between the position where the molten resin extruded from the die is cut by the cutting tool and the cooling water film covering the wall of the granule receiving casing. There will be intervals.
However, if the cut molten resin particles are retained in the air at a high temperature for a long time, there arises a problem that the resin particles come into contact with other resin particles and coalesce during the long time.

The present invention relates to a hot-cut type granulating apparatus in which a molten thermoplastic resin is granulated by being cut by a rotary cutter immediately after being extruded from a nozzle hole. It is an object of the present invention to provide a hot-cut type granulating apparatus which is small in size and has a simple structure while improving the cooling portion of the particles to prevent the resin particles from adhering.

[0007]

DISCLOSURE OF THE INVENTION According to the present invention, a die in which a plurality of nozzle holes for extruding a thermoplastic resin in a heating and melting state are opened on an extrusion surface, and a blade portion is slidably contacted with the extrusion surface of the die. In a thermoplastic resin granulating device including a rotary cutter that cuts and granulates the extruded molten resin,
A spray nozzle installed upward below the rotary cutter so as to spray cooling water in an inverted umbrella shape, and a casing mounted on the die so as to include the rotary cutter and the spray nozzle therein. After the inverted umbrella-shaped cooling water jetted from the jet nozzle passes near the edge of the rotary cutter,
By being configured to be discharged from the casing along with the resin particles that are guided and cut along the wall surface of the casing, the hot-cut resin particles stay in the air for a long time at high temperature and the resin particles are combined with each other. The ring passage for circulating the cooling water and the annular acceleration chamber connected to it, which are indispensable for the conventional hot-cut type granulator, are eliminated and the above object is achieved.

[0008]

[Operation] According to the present invention, since the molten resin extruded from the nozzle hole of the die is hot-cut by the rotary cutter, there is a reverse umbrella-shaped cooling water curtain close to the cutting position. The molten resin particles blown outward by the force immediately collide with the cooling water curtain and are cooled. Therefore, the resin particles having a high temperature in the air do not come into contact with each other to be fused.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a main part of a thermoplastic resin granulating apparatus according to the present invention. In the figure, the granulating device 1 comprises, as its main parts, an extruder 2 for extruding a thermoplastic resin while heating and melting it, and a central die part 5A and an outer peripheral die part 5B arranged on the tip side of the extruder 2. And a disk-shaped rotary driven by a motor 10 supported downward by a supporting member 39 arranged so as to cover the die 5 through a rotary shaft 11 supported by a bearing 16. And a cutter 20.

The extruder 2 is installed in the central die 5A of the die 5.
A large number of nozzle holes 8 for vertically extruding the molten resin sent through the extruding passage 3 and the distributing passage 6 formed in the central die portion 5A are formed at predetermined angular intervals on the same circumference. The blade portion 22 of the rotary cutter 20 is brought into sliding contact with the extrusion surface 5a of the die 5 in which the nozzle holes 8 are opened while rotating.

On the lower surface of the outer peripheral die portion 5B, there is an opening surrounding the rotary cutter 20, and a cover 7 made of a thin plate bent downward outside the lower end portion of the die 5.
A is attached by an appropriate method via a heat insulating material (not shown). The cover 7A is combined with a box-shaped cover 7B having an end portion that matches the end portion and a bottom portion 24 that connects to the outlet passage, and forms a casing 7 that defines a water cooling chamber A therein. The bottom portion 24 of the casing 7 has a downward slope toward the outlet so that the granulated resin particles can be smoothly discharged to the outside together with the cooling water.

At the bottom 24 of the casing 7, the rotary shaft 1 with the rotary cutter 20 attached is attached.
An opening is provided on the extension line of 1, and an injection nozzle 30 capable of stretching a water curtain W of the cooling water in an inverted umbrella shape is attached to the opening by a water conduit 32 and a bracket 34. The injection nozzle 30 is positioned so that the water curtain W of the cooling water injected from the injection nozzle 30 passes near the outer edge of the rotary cutter 20. The bracket 34 is provided with a flange having the same angle as the bottom portion 24 of the casing 7 so that the water conduit 32 becomes coaxial with the rotary shaft 11 of the rotary cutter 20.

The molten resin extruded from the extruder 2 is extruded from a large number of nozzle holes 8 provided on the die 5 on the same circumference, and the blade of a rotary cutter 20 that rotates at a high speed while slidingly contacting the extruded surface 5a. It is cut and granulated by the section 22. The cut molten resin particles P are blown outward by the centrifugal force of the rotating rotary cutter 20 and are sprayed in a reverse umbrella shape from the jet nozzle 30 attached to the tip of the water guide pipe 32. It collides with W and is cooled. After that, the resin particles P are guided along the inner wall of the casing 7 along with the flow of the cooling water, reach the casing bottom portion 24, and flow out to a dehydrating device (not shown) through the collecting and distributing passage.

Here, using a die 5 having 46 nozzle holes 8 having a diameter of 0.6 mm on a circumference having a diameter of 100 cm, the rotary speed of a rotary cutter 20 having two blade portions is set to 4500 rpm, and the die is Nozzle hole 8
To the inner surface of the inverted umbrella-shaped water curtain W is 30 mm, and the cooling water is flowed at a flow rate of 20 liters per minute by the pump 35 from the injection nozzle 30 having an inner diameter of 5 mm located directly below the rotary cutter. When polystyrene was hot-cut with the resin, resin particles having a diameter of 1.3 mm were obtained with almost no coalescence.

Thus, according to this embodiment, the die 5 is
Since the distance between the cutting position of the molten resin extruded from and the water curtain W of the cooling water can be made small, the hot-cut molten resin is immediately cooled by the cooling water curtain W,
Homogeneous resin particles can be obtained without the particles sticking together. A part of the inverted umbrella-shaped water curtain W ejected from the ejection nozzle 30 may hit the rotary cutter 20. In that case, the rotary cutter 20 is cooled, and the resin particles cut by it are also cooled to some extent on the spot and hardened, so that coalescence of the resin particles can be further suppressed, and the cutter and the die It is also possible to prevent resin particles from adhering to the surface.

[0016]

As is apparent from the above description, according to the thermoplastic resin granulating apparatus of the present invention, the conventional hot-cut granulation can be performed simply by installing the cooling water injection nozzle below the rotary cutter. Since the cooling water annular passage and the annular acceleration chamber connected to the cooling water, which are indispensable for the apparatus, are no longer required, the hot-cut type granulating apparatus can be made compact and simple. Since the cooling water from the jet nozzle is jetted and supplied as a water curtain in the shape of an inverted umbrella passing near the edge of the rotary cutter,
It becomes possible to arrange the cooling water curtain close to the cutting position of the resin, and the resin particles rush into the cooling water curtain immediately after cutting and are cooled, so that the particles can be prevented from coalescing, It is possible to stably produce homogeneous resin particles.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a main part of an embodiment of a thermoplastic resin granulating apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Granulator 2 Extruder 5 Die 5a Extrusion surface 7 Casing 8 Nozzle hole 10 Motor 11 Rotating shaft 20 Rotary cutter 22 Blade part 30 Cooling water injection nozzle 32 Water guide pipe 34 Bracket 35 Pump A Water cooling chamber P Resin grain W Inverted umbrella shape Water curtain

Claims (3)

[Claims] 1. A die in which a plurality of nozzle holes for extruding a thermoplastic resin in a heated and molten state are opened in an extrusion surface, and a blade portion is brought into sliding contact with the extrusion surface of the die to cut the extruded molten resin. In a thermoplastic resin granulating device including a rotary cutter for granulating, a spray nozzle mounted upward below the rotary cutter so as to spray cooling water in an inverted umbrella shape, the rotary cutter and the spray nozzle And a casing attached to the die so as to include the inside thereof, wherein the inverted umbrella-shaped cooling water sprayed from the spray nozzle passes near the edge of the rotary cutter and then along the wall surface of the casing. An apparatus for granulating a thermoplastic resin, characterized in that the granules are discharged together with the cut and guided resin particles from the casing. 2. The granulating apparatus according to claim 1, wherein the bottom of the casing is provided with a downward slope toward the outlet of the casing. 3. The granulating apparatus according to claim 1, wherein a part of the cooling water hits the rotary cutter.