JPH07100826A - Fine pellet for plastic molding and manufacture of fine pellet and manufacturing device thereof - Google Patents

Abstract

PURPOSE:To obtain fine pellet which can be used as it is for coating or fine film formation by extruding a molten resin passing through a screen in an extruder from a die in the form of a fine yarn, then solidifying it by a cooling air and cutting the solidified resin into micropellets. CONSTITUTION:A die for molding 3 has molding holes 5 which taper off and penetrate through in an extrusion direction, formed radially. The finest part of the molding hole 5 has a diameter of about 0.2 to 0.5mm. In addition, a rotary cutter 6 which rotates horizontally is arranged in contact with the lower surface of the die 3. Further, cooling air supply nozzles 11 are arranged in the circumferential direction of the cutter 6. After passing through the screen, the resin extruded in the form of a fine yarn is quickly cooled and then is cut into micropellets by the rotating cutter 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-made fine pellet used for molding various products using plastic as a material or for coating the surface of a metal product with the plastic, and the production of the fine pellet. It relates to a method and a manufacturing apparatus.

[0002]

2. Description of the Related Art Powdered resin is used in various plastic moldings such as powdering slush molding for manufacturing automobile interior parts and coating molding for protecting the surface of metal products with a resin film. The powder resin in this case is a molten resin extruded by a single-screw or twin-screw extruder, and has a diameter of 1.5 mm to 5 mm and a length of 2 mm to 6 mm by a method such as strand cutting or underwater cutting.
Elongate pellets of size are formed, and these pellets are pulverized by a pulverizer into powder, and 30 mesh to 80
It was formed by sieving with a mesh.

[0003]

As described above, the powdered resin used for molding various conventional plastics includes the step of forming the resin as a raw material into pellets (primary processing),
The process of crushing pellets into powder and the sieving process (secondary process) must be performed. This is because pellets molded by an extruder have a larger shape than powder and cannot be used for plastic coating or thin film molding as it is, so it is necessary to go through various steps to make powder.
Since the processing cost is high, the obtained powder resin itself is expensive. Further, the powdered resin has poor fluidity, and if it is stored as it is in a storage tank such as a tank, it spontaneously solidifies. Therefore, the storage tank needs sufficient management.

In view of the problems of the powdered resin used in the conventional plastic molding described above, the present invention forms pellets in the form of fine granules so that the pellets can be directly used in plastic coating and thin film molding. The purpose is to provide pellets. Also,
An object of the present invention is to provide a manufacturing method and a manufacturing apparatus for fine pellets.

[0005]

In order to achieve the above-mentioned object, the present invention uses a plastic molding material which is uniaxial or biaxial.
At the time of processing by the extruder 1 of the shaft, the molten resin in the pressurized state that has passed through the screen 2 in the extruder 1 is extruded into a fine thread shape by a die 4 having a large number of tapered molding holes 5 formed, and the lower surface of the die 4 is extruded. It is characterized in that the filamentous resin is solidified by the supplied cooling air and is formed into fine granules by the cutter 6.

Further, according to the present invention, a step of extruding the molten resin in a pressurized state filtered in the extruder 1 into a fine thread shape by a die 4 having a large number of tapered molding holes 5, and a lower surface of the die 3 by cooling air. It is characterized in that it comprises a step of solidifying the thread-shaped resin extruded in the above, and a step of forming the solidified thread-shaped resin into a fine granular shape by the rotary cutter 6.

Further, according to the present invention, below the screen 2 installed in the head portion of the extruder 1, a die 4 having a large number of finely tapered forming holes 5 radially formed is installed,
On the lower surface of the die 4, a rotary cutter 6 having a plurality of cutter blades 9 having a shearing blade 10 on the tip side in the rotation direction is installed so as to be in contact with the lower surface of the die 4, and the die 4 is arranged in the circumferential direction of the cutter 6. It is characterized in that a plurality of nozzles 11 capable of supplying cooling air are provided below.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows the whole apparatus used in the method of the present invention, and the reference numeral 1 is the same single axis or 2 as in the conventional case.
It is a shaft extruder, a screen 2 is provided at the head portion of the extruder 1, and a molding die 3 is provided below the screen 2.
Is installed so as to be integrated with the extruder 1.

The screen 2 has a filter function for removing fiber dust such as paper and cloth mixed in the resin and other impurities such as dust, and is supplied from above the extruder 1 under pressure. The melted resin is all screen 2
Filtered through. The screen 2 is conventionally known.

As shown in FIGS. 1 and 2, the molding die 3 is formed by forming a large number of molding holes 5 in a metal disk body 4 in the radial direction, and each molding hole penetrating in the extrusion direction. 5 has a tapered shape, and the thinnest part of the molding hole 5 has a diameter of 0.2 mm to 0.5 mm.

A rotary cutter 6, which is in contact with the lower surface of the molding die 3 and is rotatable in the horizontal direction, is installed on a driving device 7 so as to be concentric with the die 3. As shown in FIG. 3, this cutter 6 has a plurality of cutter blades 9 projecting in a radial direction around a rotary shaft 8, and the tip end side of each cutter blade 9 in the rotation direction is a thin blade-shaped shear blade 10. It was done.

In FIG. 1, reference numeral 11 denotes cooling air supply nozzles installed in the circumferential direction of the cutter 6, and each nozzle 11 is directly connected to an air supply device (not shown) installed outside the device. Cooled dry air is always supplied to the lower surface of the die 3 from each nozzle 11, and the temperature of this air is adjusted to 5 ° C to 15 ° C.

The apparatus of the present invention has the above-mentioned structure. Next, the pellet manufacturing process will be described. The molten resin is pressed into the inside of the extruder 1 from above, and is filtered through the screen 2. The filtered resin is supplied while applying pressure to the upper surface of the die 3, and is continuously extruded in a very thin thread shape from the large number of molding holes 5 formed in the die 3. Since cooling air is supplied from the plurality of nozzles 11 to the lower surface of the die 3, the resin extruded in the form of thin threads is quickly cooled, and the shear blade 10 of the cutter 6 rotated by the drive motor in the drive device 7 is cooled. Sheared into fine granules by
A large number of pellets are continuously formed.

Since the thinnest hole diameter of each molding hole 5 is 0.2 mm to 0.5 mm as described above, the diameter of the filamentous resin extruded from the molding hole 5 is regulated within that range. Further, the length of the filamentous resin is determined by the number of rotations of the cutter 6, but a length size within the range of 0.2 mm to 0.5 mm is usually selected.

[0015]

As described above, according to the present invention described above, the molten resin that has passed through the screen 2 is pressed into a die 4 having a large number of molding holes 5 and supplied, and when it is extruded from the molding holes 5, it melts. The resin is in the form of fine long threads corresponding to the small diameter of the molding hole 5. Since the resin is in the form of fine threads, when it is rapidly cooled by the cooling air supplied to the lower surface of the die 3 and solidified, it is sheared by the rotary cutter 6, and the pellets thus formed become extremely fine granules.

The fine granular pellets can be formed by primary processing, and since the pellets can be used as they are for plastic molding, the processing cost can be greatly reduced, so that inexpensive plastic molding materials can be supplied. .
Moreover, since the pellets thus obtained are in the form of granules, they do not spontaneously solidify, have a fluidity,
It will be easy to store.

[Brief description of drawings]

FIG. 1 is a sectional view of an apparatus for producing a plastic molding pellet of the present invention.

FIG. 2 is a plan view of a molding die.

FIG. 3 is a perspective view of a rotary cutter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Extruder 2 Screen 3 Molding die 4 Disc body 5 Forming hole 6 Rotary cutter 7 Drive device 8 Rotating shaft 9 Cutter blade 10 Shearing blade 11 Cooling air nozzle

Claims (3)

[Claims] 1. A plastic molding material is uniaxial or biaxial.
At the time of processing by the extruder 1 of the shaft, the molten resin in the pressurized state that has passed through the screen 2 in the extruder 1 is extruded into a fine thread shape by a die 4 having a large number of tapered molding holes 5 formed, and the lower surface of the die 4 is extruded. A fine pellet for plastic molding, characterized in that the filamentous resin is solidified by the supplied cooling air and formed into fine granules by the cutter 6. 2. A plastic molding material is uniaxial or biaxial.
When processing with the extruder 1 of the shaft, the molten resin in a pressurized state filtered in the extruder 1 is extruded into a fine thread by a die 4 having a large number of tapered molding holes 5, and a die 3 is provided with cooling air. The step of solidifying the thread-shaped resin extruded on the lower surface and the rotary cutter 6
The method for producing fine pellets for plastics molding, comprising the step of forming into fine granules. 3. A plastic molding material is uniaxial or biaxial.
When processing with the axial extruder 1, a die 4 having a large number of finely tapered forming holes 5 formed in the radial direction is installed below the screen 2 installed in the head portion of the extruder 1, and the die 4 On the lower surface, the shear blade 10 is provided on the tip side in the rotation direction.
The rotary cutter 6 having a plurality of cutter blades 9 is installed as if in contact with the lower surface of the die 4, and a plurality of nozzles 11 capable of supplying cooling air are provided below the die 4 in the circumferential direction of the cutter 6. An apparatus for producing fine pellets for plastic molding, which is characterized in that