JP2009160842A - Plastic extruding method and extruder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a homogeneous plastic product, in case a low bulk density material, such as crushed plastic scraps, crushed organic fibers and waste papers and wood dusts, is used together with an ordinary plastic material (pellets) and these are kneaded, molten and extruded with an extruder to produce a plastic product, even if the low bulk density material is directly supplied into the extruder without pelletization. <P>SOLUTION: The plastic pellets and the low bulk density material are supplied into the extrusion cylinder from different material feed throats. The low bulk density material is supplied using the screw feeder 23, the tip of the casing 32 is arranged to the material feed throat of the extrusion cylinder 4, and the material is compressed while being delivered forward with the screw 34 and forced into the grooves of the extrusion screw 34. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an extrusion method and an extruder in which two or more kinds of plastic materials having different bulk densities are kneaded, melted and extruded.

  For recycling, resource saving or other purposes, pulverized plastic scrap (blow molded product burr, film, tape, foam sheet ear, Thomson cutting scrap, etc.) as a part of plastic material, other plastic It is known that a plastic product is manufactured by supplying kneading, melting, and extrusion molding together with a material, or by pulverizing organic fibers, waste paper, wood powder and the like together with a plastic material as a base material.

  For example, in Patent Document 1, a plastic material (pellet) and wood powder are mixed in an hopper of an extruder, supplied into an extrusion cylinder, kneaded and melted, and extruded from the tip of the extrusion cylinder to produce a plastic product. It is described to do. However, when mixing in the hopper of the extruder in this way, wood powder generally has a lower bulk density than the plastic material used as the base material (the same is true for pulverized plastic scraps, pulverized organic fibers and waste paper). There is a problem in that it is separated from the plastic material and is not supplied uniformly into the extrusion cylinder, so that a homogeneous plastic product cannot be obtained.

  In the case of plastic scrap, the pulverized product is kneaded and melted separately with an extruder, extruded and molded into pellets (see Patent Document 2), and then mixed with non-recycled pellets as necessary. Kneaded and melted again with an extruder for products, extruded to produce a product, or in the case of wood flour, etc., kneaded, melted and extruded with a plastic material as a base material with a special extruder It is also known that, after being pelletized, it is kneaded and melted again by a product extruder and extruded to produce a product. However, once pelletizing in this way, there are problems that the number of processes increases, the cost increases, the heating history increases, material deterioration occurs, and product quality decreases.

Japanese Patent Laid-Open No. 2004-58271 JP 2006-297855 A

  The present invention uses ordinary plastic materials (pellets) and materials with low bulk density such as pulverized plastic scraps, pulverized organic fibers and waste paper, wood flour, etc., and these are kneaded and melted by an extruder. In the case of producing a plastic product by molding, an object is to make it possible to produce a homogeneous plastic product even if the material having a small bulk specific gravity is directly supplied to an extruder without being pelletized.

The method of extruding a plastic according to the present invention is a method of extruding plastic by an extruder in which two or more kinds of plastic materials having different bulk densities are supplied into an extrusion cylinder, kneaded with an extrusion screw, melted and extruded from the tip of the extrusion cylinder. In the method, the plastic material is classified into two or more according to the size of the bulk density, and the plastic material is supplied into the extrusion cylinder from different material supply ports. Is compressed using a screw feeder disposed at the material supply port of the extrusion cylinder and pushed into the groove of the extrusion screw. In addition, in this invention, the material which becomes the origin of a plastic product including the normal plastic material (pellet) used as a base material is called plastic material.
In the above extrusion method, all the classified plastic materials can be supplied by using a screw feeder in which the tip of the casing is arranged at the material supply port of the extrusion cylinder. The plastic material classified as the lowest bulk density is, for example, a plastic scrap pulverized product, or one or more of organic fiber, pulverized waste paper or wood powder.

  The plastic extruder according to the present invention kneads and melts two or more kinds of plastic materials having different bulk densities and extrudes them from the tip portion, and forms at least two material supply ports in the extrusion cylinder, and at least The screw feeder is installed for one material supply port, the tip of the casing of the screw feeder is arranged in the material supply port, and the plastic material is compressed and pushed into the groove of the extrusion screw. To do. In this extruder, screw feeders may be installed for all material supply holes, and the tips of the casings of the screw feeders may be arranged at the material supply ports.

In the extrusion method according to the present invention, a plastic material having a small bulk density, such as a pulverized plastic scrap, a pulverized organic fiber or waste paper, and wood powder, is compressed by being pumped by a screw feeder and directly pressed into a groove of an extrusion screw. The bulk density can be increased and the bulk density can be made almost constant, and it can be supplied in a state close to a constant rate supply. Since the supplied material is taken into the extrusion cylinder by the extrusion screw, the plastic material can be fed into the entire plastic material without being pelletized. Therefore, the ratio of these materials is prevented from greatly fluctuating, and a homogeneous plastic product can be manufactured.
In addition, since there is no pelletizing step, the manufacturing cost is reduced, the heating history is not increased, material deterioration does not occur, and the quality of the plastic product is not easily lowered.
In the extrusion method according to the present invention, the plastic material is degassed by compressing with a screw feeder to increase the bulk density. As a result, the amount of air taken into the extrusion cylinder is reduced. There is also an advantage that there is no need to use a vent extruder.

Hereinafter, the extrusion method and the extruder according to the present invention will be described with reference to FIGS.
The extruder shown in FIG. 1 manufactures a parison for blow molding, and the main body has basically the same structure as that described in JP-A-8-57941. The main body portion includes upper and lower fixed plates 2 and 3 connected by a tie bar 1, a cylindrical extrusion cylinder 4 whose upper end is fixed to the lower fixed plate 3, and a screw on the outer periphery, and is rotatable in the extrusion cylinder 4 A cylindrical screw plunger 5 that is axially movable back and forth; a rod 6 that extends through the screw plunger 5 in the axial direction; and a nozzle die 7 disposed on the extrusion side of the extrusion cylinder 4; A core die 8 fixed to the tip of the rod 6 and disposed inside the nozzle die 7, a rotating mechanism for rotating the screw plunger 5, an advancing / retreating mechanism for moving back and forth in the axial direction, and a lifting / lowering mechanism for the rod 6 are provided.
The nozzle die 7 includes a taper ring 9 and a ring die 11 positioned in front of the taper ring 9, and constitutes a die hole 12 together with the core die 8. The screw plunger 5 is rotatable around the rod 6 and is slidable in the axial direction.

The rotation mechanism that rotates the screw plunger 5 is installed between the upper and lower fixed plates 2 and 3 and includes a drive motor 13, a speed reducer 14, and a transmission mechanism housed in a gear box 15, and this transmission mechanism is a screw. It is connected to the upper part of the plunger 5. When the drive motor 13 rotates, the screw plunger 5 rotates in the extrusion cylinder 4 via the speed reducer 14 and the transmission mechanism.
The forward / backward mechanism for moving the screw plunger 5 back and forth in the axial direction includes a cylinder 16 installed on the upper fixed plate 2 and a pusher plate 18 fixed to the tip of the piston rod 17. Box 15 is fixed. The operation of the cylinder 16 advances and retracts the rotation mechanism, and advances and retracts the screw plunger 5 in the axial direction.

The lifting mechanism of the rod 6 includes a cylinder 19 installed on the upper fixing plate 2 and an internal piston (not shown), and the upper end of the rod 6 is fixed to the piston. The piston is supported in the cylinder 19 so that the vertical position can be adjusted, and the vertical position of the core die 8 can be adjusted to adjust the distance between the nozzle die 7 and the core die 8 (this gap is the die hole 12), thereby adjusting the thickness of the parison. It is like that.
Reference numeral 21 denotes a heater.

A material supply port (not shown) is formed at an angle of approximately 90 degrees on the side wall of the extrusion cylinder 4, and a screw feeder 22 and a screw feeder 23 for recycling the burrs of the blow molded product are provided for each material supply port. is set up. The screw feeders 22 and 23 are known per se. The hoppers 24 and 25, the motors 26 and 27, the transmission mechanism in the boxes 28 and 29, the cylindrical casings 31 and 32 protruding forward from the lower part of the hopper, The arranged screws 33 and 34 are provided, and the tips of the casings 31 and 32 are arranged at the material supply ports, respectively.
The screw feeder 22 supplies normal plastic pellets (non-recycled products) to the grooves of the screw plungers 5 through the material supply holes at a constant rate, and the screw feeder 23 crushes scrap (blows of blow molded products) in the hopper 25. The object is compressed while being fed forward, and is forcedly pushed into the groove of the screw plunger 5 through the material supply hole, and supplied in a form close to a constant rate supply.

  The extruder shown in FIG. 2 is a known extruder with a main body portion, and two screw feeders 41 and 42 are attached to the extruder. This main body portion includes a cylindrical extrusion cylinder 43, an extrusion screw 44 having a screw on the outer periphery and being rotatable within the extrusion cylinder 4, a nozzle die 45 disposed on the extrusion side of the extrusion cylinder 43, an extrusion A drive mechanism 46 for rotating the screw 44 is provided. Reference numeral 47 denotes a heater.

Two material supply ports (not shown) are formed in the upper part and the side part of the side wall of the extrusion cylinder 43, and the well-known screw feeders 41 and 42 are installed in each material supply port. The screw feeder 41 includes a hopper 51, a motor 52, a transmission mechanism in the box 53, a cylindrical casing 54 protruding forward from the lower portion of the hopper 51, and a screw 55 disposed in the casing 54. The screw feeder 42 includes a hopper 56, a motor 57, a cylindrical casing 58 following the hopper lower part, a screw 59 arranged in the casing 58, and two charging hoppers 61 and 62 serving as charging ports for charging a plastic material into the hopper 56, The tips of the casings 54 and 58 are respectively disposed in the material supply ports. A stirring blade 63 is attached to the shaft of the screw 59 so that two types of plastic materials fed into the hopper 56 via the feeding hoppers 61 and 62 can be stirred and mixed.
The screw feeder 41 supplies normal plastic pellets (non-recycled products) at a constant rate to the grooves of the extrusion screw 44 through the material supply holes, and the screw feeder 42 crushes two types of plastic materials having a low bulk density, such as waste paper. The material and the wood flour are agitated and mixed in the hopper 56, compressed while being sent downward, and forcedly pushed into the groove of the extrusion screw 44 through the material supply hole, and supplied in a form close to a constant rate supply.

It is a partial cross section perspective view of the extruder which concerns on this invention. It is a partial cross section perspective view of the extruder which concerns on this invention.

Explanation of symbols

22, 23, 41, 42 Screw feeder 31, 32, 54, 58 Casing 33, 34, 55, 59 screw

Claims (6)

In a method of extruding a plastic by an extruder, two or more kinds of plastic materials having different bulk densities are supplied into an extrusion cylinder, kneaded and melted by an extrusion screw, and extruded from the tip of the extrusion cylinder. It is classified into two or more according to size, and this is supplied into the extrusion cylinder from different material supply ports. Among the plastic materials classified at least as the lowest bulk density, the tip of the casing is arranged at the material supply port of the extrusion cylinder. A method for extruding a plastic, characterized by using a screw feeder and compressing it into a groove of an extrusion screw. 2. The method of extruding plastic according to claim 1, wherein all plastic materials are supplied using a screw feeder in which a front end of the casing is disposed at a material supply port of an extrusion cylinder. 3. The method for extruding plastic according to claim 1, wherein the plastic material classified as the lowest bulk density is a pulverized product of plastic scrap. 3. The plastic extrusion according to claim 1 or 2, wherein the plastic material classified as the lowest bulk density is one or more of organic fibers, pulverized waste paper, or wood flour. Method. In a plastic extruder in which two or more kinds of plastic materials having different bulk densities are kneaded, melted and extruded from the tip, two or more material supply ports are formed in the extrusion cylinder, and at least one material supply port A plastic extruder, wherein a screw feeder is installed, a tip of a casing of the screw feeder is disposed at the material supply port, and a plastic material is compressed and pushed into a groove of an extrusion screw. 6. The plastic extruder according to claim 5, wherein screw feeders are installed in all the material supply holes, and a tip of a casing of the screw feeder is disposed in the material supply port.

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