JPH0976328A - Method and apparatus for extrusion molding long fiber-reinforced thermoplastic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the bending or breakage of long fiber to the minimum limit and to enhance the strength by heating and melting pelletlike long-fiber reinforced thermoplastic resin, then pressurizing it to open it, and further there after extruding it by a plunger type extruder. SOLUTION: Pellet made of thermoplastic resin mixed with long fiber is introduced to a hopper 16, and the outer periphery of a cylinder 4 is heated by a heater 21. Then, the pellet is fed to the outlet 20 side of the cylinder 4 while mixing the pellet by screws 5, 6. Since the screws 5, 6 have deep channels and low compression ratio, large kneading is not conducted, and the long fiber does not become fine. Then, it is drawn between rolls 23. At this time, the long fiber is further opened. Then, it is introduced from the outlet 29 of a roll box 24 into an accumulator chamber 32, a plunger 31 is pressed to supply it to the cylinder chamber 42 of a plunger type extruder 3. Thereafter, the outlet 35 of the switching valve 36 is closed, and it is extruded from an extrusion die 43 by a hydraulic cylinder 39.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a plunger type extruder to form a profile made of a pellet-shaped thermoplastic resin material reinforced by fibers such as glass having a relatively long length (about 3 mm to 25.4 mm). The present invention relates to an extrusion molding method and apparatus for extrusion.

[0002]

2. Description of the Related Art Conventionally, a rod-shaped material or a deformed cross-section material has been molded by an extrusion molding method using a fiber reinforced resin obtained by mixing fibers such as glass into a thermoplastic resin and reinforcing the resin. As the extrusion molding device in this case, a conventional uniaxial or biaxial kneading extrusion molding device is generally used. The resin is plasticized by a screw and kneaded with the fiber, and the resin kneaded with the fiber is further discharged. By extruding through a extrusion die set to, a long product having a rod-shaped material or a modified cross-section material is molded. Further, by changing the shape of the extrusion die set at the outlet, long products having various cross-sectional shapes can be molded.

[0003]

In the above-mentioned conventional extrusion molding apparatus, the glass fiber to be supplied is subjected to a large shearing force because it is mixed with the resin plasticized by one or two screws, and therefore, However, even if long fibers are used, they are broken during the kneading process, and most of the fiber length in the resin is less than 1 mm by the time it is extruded from the extrusion die. It is difficult to apply.

The present invention has been made based on the above-mentioned circumstances, and an object thereof is to plasticize a long-fiber-reinforced thermoplastic resin in pellet form with minimum damage to the fiber, and to make the fiber in the pellet (EN) An extrusion molding method and apparatus capable of extruding a high-strength long-fiber-reinforced thermoplastic resin by melting a resin while defibrating a bundle while maintaining the fiber length.

[0005]

In order to achieve the above object, a method for extrusion molding a long fiber reinforced thermoplastic resin according to the present invention, a pellet-shaped long fiber reinforced thermoplastic resin is heated and melted, and then melted. The long-fiber-reinforced thermoplastic resin in the state is pressed and defibrated, and then extruded by a plunger type extruder.

In the method of extrusion-molding the long fiber reinforced thermoplastic resin, the long fiber reinforced thermoplastic resin in a molten state after being heated and melted is placed between two rolls arranged in parallel with each other and rotating in different directions. You may defibrate through the gap of.

In order to achieve the above object, the extrusion molding apparatus for long fiber reinforced thermoplastic resin according to the present invention has two screws having deep grooves and a low compression ratio, which are parallel to each other in a cylinder equipped with a heater. A twin-screw plasticizing device for melting and kneading pellet-shaped long-fiber reinforced thermoplastic resin by arranging it in the same direction and rotating in different directions, and a screw-type plasticizing device connected to the outlet of this screw-type plasticizing device. Pressure applying means for applying pressure to the molten long fiber reinforced thermoplastic resin to defibrate it, and introducing and pushing the molten long fiber reinforced thermoplastic resin from the outlet connected to the outlet of this pressure applying means. It consists of a plunger-type extruder that ejects.

Further, in the above-mentioned long-fiber-reinforced thermoplastic resin extrusion molding apparatus, an accumulator consisting of a cylinder and a plunger may be provided between the outlet of the pressure applying means and the extruder.

In the above-mentioned method of the present invention, the thermoplastic resin pellets reinforced by the long fibers of about 3 mm to 25.4 mm are heated and melted, and the long fiber reinforced thermoplastic resin in the molten state is pressed and spread to be melted. Since it is fine, unlike the conventional method of melting only, or unlike kneading with a screw after melting or at the same time after melting, a long-fiber reinforced thermoplastic resin in a molten state with less breakage of fibers and less clumping of fibers is used. Obtainable. In addition, since this is extruded by the plunger type extruder, the breakage of the fiber is small even in this extruded molding, and therefore relatively long fibers are relatively uniformly dispersed in the extruded molded product. Therefore, an extruded product having excellent surface properties and strength can be obtained.

Further, since the device of the present invention is constructed as described above, 3 mm to 25.4 in the cylinder of the screw type plasticizing device.
When the thermoplastic resin pellets reinforced by long fibers of about mm are supplied, the pellets are heated and melted by the heater provided in the cylinder, and the pellets of two parallel screws with deep grooves and low compression ratio are different. By rotating in the direction, the molten resin and the long fibers are kneaded. In this kneading, since the groove shape of the screw is a low compression ratio shape of, for example, about 1 to 1.5, and since it is two screws (so-called biaxial screw), compared with the case of using one screw. Since the molten resin is mainly transported and mixed, shearing force is hardly generated, so that breakage of long fibers is reduced. In this way, while the pellets are melt-kneaded (kneading mainly for mixing) in the cylinder, the two parallel screws are rotated in different directions so that the long fibers are conveyed with less breakage and are screw-type plasticized. It is sent from the outlet of the device to the pressure applying means. In the pressure applying means, pressure is applied to the long-fiber-reinforced thermoplastic resin in a molten state to apply pressure, so that the aggregate of the long fibers can be effectively disentangled with less breakage of the fibers. As a specific method of obtaining such a defibrated state, it can be carried out by passing through the gap of a pair of rolls which are arranged in parallel with each other and which are arranged so as to have a gap between the rolls and which rotate in different directions. The melted long-fiber-reinforced thermoplastic resin thus defibrated is then sent to a plunger-type extruder and extruded by this plunger-type extruder to be molded into an extruded product. It can be extruded into a long-fiber-reinforced thermoplastic resin product having a high strength and a minimum strength. In order to obtain such an action, the compression ratio of the groove shape is preferably about 1 to 1.5, more preferably about 1 to 1.2. The reason is to reliably transport the molten resin by the screw, reduce the shearing to the molten resin due to the screw rotation, and prevent the fiber from being damaged.

Further, an accumulator consisting of a cylinder and a plunger is provided between the outlet of the pressure applying means and the plunger type extruder to reduce the breakage of the fiber by the screw type plasticizing device and the pressure applying means. The long-fiber-reinforced thermoplastic resin in a molten state that has been relatively uniformly disintegrated by the accumulator can be accumulated in the accumulator and can be supplied into the plunger type extruder by opening the on-off valve provided at the outlet. By adjusting the operation timing, it becomes possible to efficiently supply the long fiber reinforced thermoplastic resin into the plunger type extruder through the accumulator while continuously operating the screw type plasticizing device and the pressure applying means.

[0012]

1 is a front sectional view of a long fiber reinforced thermoplastic resin extrusion molding apparatus according to the present invention, and FIG.
4 is a sectional view taken along line AA of FIG. 3, FIG. 3 is a sectional view taken along line BB of FIG.
FIG. 3 is a sectional view taken along line CC of FIG. 1. In this figure, 1 is a twin-screw plasticizing device, 2 is an accumulator device,
3 shows a plunger type extruder.

First, the biaxial screw plasticizing device 1 will be described. In the cylinder 4, screws 5 and 6 that rotate in different directions are arranged in parallel. Each screw 5, 6 is 1
A screw is used, and the teeth 7, 8 of each screw have a cross-sectional shape as shown in FIG. 3 and are constant in the axial direction, and the grooves formed by the teeth 7, 8 are deep grooves and are mutually It has a low compression ratio (compression ratio 1 to 1.5) that meshes with.

Each of the screws 5 and 6 has one end penetrating the cylinder 4 and is supported in an external gear box 9 with a gear 11 attached to its shaft portion 10 interposed therebetween. The attached motors 12 rotate in different directions. On the other hand, the other end is inside the cylinder 4 and the head 13 is formed in a conical shape. In addition, holes 14 and 15 for providing heating means may be formed in the center of the shaft portion 10.In this case, the holes 14 and 15 are holes from the rear to the front of the head 13,
A heat medium may be allowed to flow inside, or a cartridge heater may be inserted.

A hopper 16 is provided in the vicinity of one end of the cylinder 4, and a lower opening of the hopper 16 communicates with an opening 18 at one end of a cylinder chamber 17 inside the cylinder 4 so that long fibers fed from the hopper 16 are mixed. It is possible to accept the pellets of the thermoplastic resin. The other end of the cylinder 4 is formed into a tapered funnel-shaped inclined portion 19 along the cone or hemisphere of the head 13 of the screws 5 and 6, and the tip thereof is formed into a slit-shaped outlet 20. An electric heater 21 is provided on the outer periphery of the cylinder 4, and the inside of the cylinder chamber 17 is 200 to 400
When the pellets, which are heated to about 0 ° C. and fed from the hopper 16, are conveyed from one end to the other end in the cylinder chamber 17 by the rotation of the screws 5 and 6 in different directions, the pellets are heated and melted. In this embodiment, the pressure applying roll device 22 as a pressure applying means is connected to the tip of the inclined portion 19, and the accumulator device 2 is further connected to the tip thereof.

The pressure applying roll device 22 is a roll box having a pair of rolls 23 arranged in parallel with each other inside.
24, a gear box 26 having a gear connected to the shaft of the roll 23 via a coupling 25, and a motor 28 connected to any one gear shaft in the gear box 26 via a coupling 27. The pair of rolls 23 are rotated in a direction of drawing out the molten resin conveyed to the tip outlet 20 of the cylinder 4 through the gears in the gear box 26 by the drive of the motor 28, and the molten resin is pressurized and mixed. The long fibers in the roll box 24 are defibrated (the fibers are loosened to improve the impregnation of the fibers with the resin), and the filaments are sent out from the outlet 29 of the roll box 24 to the accumulator device 2. Instead of the pressure applying roll device 22, an elongated opening may be formed by a gate to apply pressure.

The accumulator device 2 comprises a cylinder 30 and a plunger 31, and an accumulator chamber 32 is formed on the tip end side of the plunger 31. Accumulator room
The periphery of 32 is heated by a heater (not shown). A pushing hydraulic cylinder 34 is connected to the rear end of the plunger 31 via a rod 33. The tip end outlet 35 of the accumulator chamber 32 is connected to the plunger type extruder 3 with an opening / closing valve 36 interposed. As shown in FIG. 4, the opening / closing valve 36 is configured such that the stopper plate 37 can freely move in and out of the outlet 35 by the drive cylinder 38. The open / close valve 36 has a configuration other than that described above.
It may be a rotary valve type or another type of opening / closing valve.

The plunger type extruder 3 has a hydraulic cylinder 39.
By pushing out the plunger 41 in the cylinder 40 by the operation of, the resin supplied into the cylinder chamber 42 can be extruded from the extrusion die 43. Further, a heater (not shown) is provided on the outer periphery of the cylinder 40, and the cylinder chamber 42
The inside can be maintained at a predetermined temperature. Reference numeral 44 denotes a cooling water tank for cooling and solidifying the extruded long fiber reinforced thermoplastic resin. Further, instead of the cooling water tank 44, the extruding die 43 may be formed with a long tip portion and cooled while passing through the tip portion.

In the operation of the above-mentioned apparatus, first, the hopper 16 is charged with pellets made of a thermoplastic resin in which glass fibers of 3 to 25.4 mm, that is, long fibers are mixed in advance.
By heating the outer circumference of the cylinder 4 with the heater 21, the inside of the cylinder chamber 17 is heated to about 200 to 400 ° C. Motor 12
To rotate the two screws 5 and 6 in different directions at the same speed via the gear 11 of the gear box 9,
The pellets supplied into the cylinder chamber 17 through the lower openings 18 of the 16 are conveyed from one end of the cylinder chamber 17 to the other end. At that time, since the screws 5 and 6 are deep grooves and have a low compression ratio, the pellets are mainly transported and mixed without large kneading. Therefore, the internal long fibers are finely broken by the shearing force at the time of kneading. Is prevented.

In this way, the pellets in the cylinder 4 are melted by the insufficient heating due to shearing due to the operation of the screws 5 and 6 being compensated by the heating means, and the outlet 20 of the cylinder 4 is melted.
Sent to the side. The gas generated at this time is discharged to the outside from a vent port or hopper 16 (not shown). The molten resin sent to the outlet 20 side of the cylinder 4 is drawn out between the rolls 23 of the pressure applying roll device 22 which rotate in mutually different directions. At this time, the molten resin is pressed between the rolls 23 to further disentangle the long fibers mixed in the molten resin (to loosen the fiber bundle and improve the impregnation of the resin into the fibers). The molten resin drawn between the rolls 23 is
It is further sent to the accumulator device 2 from the outlet 29 of the. The stopper plate 37 of the opening / closing valve 36 is advanced and closed at the tip outlet 35 of the accumulator device 2, and the molten resin sent from the pressure applying roll device 22 fills the accumulator chamber 32. Thereafter, the stopper plate 37 of the opening / closing valve 36 is retracted to open the outlet 35, and the pushing hydraulic cylinder 34 is operated to push the plunger 31 to push the molten resin in the accumulator chamber 32 into the cylinder of the plunger type extruder 3. Supply into the chamber 42.

After that, the stopper plate of the opening / closing valve 36
37 and the outlet 35 are closed, and the hydraulic cylinder 39
Is operated to move the plunger 41 forward, the resin supplied into the cylinder chamber 42 is extruded from the extrusion die 43.
After the extrusion is completed, the stopper plate 37 of the open / close valve 36 is again used.
Is opened to open the outlet 35, the molten resin in the accumulator chamber 32 is supplied into the cylinder chamber 42 of the plunger type extruder 3, and the extrusion operation by the plunger type extruder 3 is repeated. Since the relatively long fibers are relatively evenly dispersed in the extruded product 45 thus extruded, an extruded product having excellent surface properties and strength can be obtained.

In the above-mentioned apparatus, the resin melting /
Various shapes of the screws 5 and 6 to be kneaded are used, but the ratio H / D of the groove depth to the shaft diameter is preferably about 0.2 to 0.3, and the compression ratio is preferably about 1 to 1.5. Within this range, kneading mainly involving transportation and mixing of long fibers with little breakage can be performed. Also, the ratio of screw length to diameter L
It is suitable that / D is about 5 to 15.

In the above embodiment, the case where one plunger type extruder 3 is provided has been described as an example, but the extrusion die 43 is used.
By disposing two (2 or more) plunger type extruders 3 so as to be commonly used and alternately extruding with these plunger type extruders 3, continuous extrusion can be performed,
As a result, a long product having an arbitrary constant cross section that is not limited to the length can be formed. Further, a cutting machine may be provided after the cooling water tank to cut into a fixed length.

[0024]

EFFECTS OF THE INVENTION Since the present invention is constituted and operates as described above, even when the pellet-shaped long fiber reinforced thermoplastic resin is melt-kneaded and extruded, the bending and breakage of the internal long fibers are reduced to a minimum. It is possible to obtain an extruded product of long-fiber-reinforced thermoplastic resin having high strength.

[Brief description of drawings]

FIG. 1 is a front sectional view of an apparatus for extrusion molding a long fiber reinforced thermoplastic resin according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is a sectional view taken along line CC of FIG.

[Explanation of symbols]

1: Twin screw plasticizing device 2: Accumulator device 3: Plunger type extruder 4: Cylinder
5,6: Screw 7,8: Screw teeth 9: Gear box 1
0: Shaft 11: Gear 12: Motor 1
3: Head 14, 15: Hole 16: Hopper 1
7: Cylinder chamber 18: Opening 19: Inclined part 2
0: slit-shaped outlet 21: electric heater 22: pressure applying roll device 2
3: Roll 24: Roll box 25: Coupling 2
6: Gear box 27: Coupling 28: Motor 2
9: Outlet 30: Cylinder 31: Plunger 3
2: Accumulator chamber 33: Rod 34: Hydraulic cylinder for pushing 35: Tip outlet 36: Open / close valve 3
7: Stopper plate 38: Drive cylinder 39: Hydraulic cylinder 4
0: Cylinder 41: Plunger 42: Cylinder chamber 4
3: Extrusion die 44: Cooling water tank 45: Extrusion molded product

Claims (4)

[Claims] 1. A method of heating and melting a pellet-shaped long-fiber-reinforced thermoplastic resin, pressurizing the melted long-fiber-reinforced thermoplastic resin to defibrate it, and then extruding it by a plunger type extruder. A method for extrusion-molding a long-fiber-reinforced thermoplastic resin characterized. 2. The extrusion of a long-fiber-reinforced thermoplastic resin according to claim 1, wherein the molten long-fiber-reinforced thermoplastic resin is defibrated through a gap between two rolls arranged in parallel with each other and rotating in different directions. Molding method. 3. A pellet-shaped long-fiber-reinforced thermoplastic resin is melted by disposing two deep groove and low compression ratio shaped screws in a cylinder equipped with a heater in parallel with each other and rotating them in different directions. A twin-screw type plasticizing device for kneading, a pressure applying means connected to the outlet of the screw type plasticizing device for applying pressure to the molten long fiber reinforced thermoplastic resin from the outlet to defibrate, and An extrusion molding apparatus for long-fiber reinforced thermoplastic resin, comprising a plunger type extruder connected to the outlet of the pressure applying means and introducing and extruding the molten long-fiber reinforced thermoplastic resin from the outlet. 4. An apparatus for extrusion molding a long fiber reinforced thermoplastic resin according to claim 3, wherein an accumulator comprising a cylinder and a plunger is interposed between the outlet of the pressure applying means and the extruder.