JPH10315299A - Manufacture of resin pipe and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a resin pipe excellent in mechano-physical properties without lowering its productivity by a method wherein a melt, which is prepared by kneading a thermoplastic resin composition with an extruder, is extruded from a die equipped with a specified mandrel so as to be formed into the shape of the pipe. SOLUTION: A resin composition as stock is fed through a hopper 1 into an extruder 2 so as to be melted and kneaded in the extruder. The extruder 2 is a twin contrarotating screw extruder, which has a plurality of screw flights 13 and two screws 19 rotating in opposite directions. The resultant resin melt is fed through an adapter 3 to the runner 4 of a die 15 so as to apply vibration to the resin melt with a mandrel 8, which has a tapered part 16 with a gradient of 10-90 deg. and vibrate in the extrusion direction of the resin melt in the frequency of 10-50 kHz. As a result, the vibration, which has a component in the direction of the thickness of the pipe, is given to the resin flowing in the die 15, resulting in accelerating the kneading of the resin composition. Next, the predetermined amount of the resin melt is extruded from a resin discharging port 6 so ass to obtain the desired sized resin pipe 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin pipe manufacturing apparatus and a manufacturing method using the same. For more information,
The present invention relates to a resin pipe manufacturing apparatus having excellent physical properties such as mechanical strength, and a manufacturing method using the same.

[0002]

2. Description of the Related Art Resin pipes having an outer diameter of about 10 mm to 200 mm are generally used as pipes for transporting fluids such as tap water, sewage, hot water, and the like. In particular, tubes made of vinyl chloride resin
Since it is inexpensive and has excellent mechanical properties, flame retardancy, and weather resistance, it is preferably used.

In general, in order to manufacture a resin tube, a thermoplastic resin composition is melt-kneaded using an extruder, extruded from a die having a cylindrical mandrel called a mandrel, and formed into a tube. It is obtained by cooling. At this time, the performance (such as mechanical strength) of the resin tube often depends on the degree of kneading of the resin composition in the extruder. In particular, for a vinyl chloride resin, the correlation between the kneading degree of the resin composition and the mechanical strength of the molded article is remarkable.

[0004] A vinyl chloride resin is usually produced by a water suspension polymerization method, and resin particles produced by this method contain polyvinyl alcohol, which is used as a dispersant during polymerization,
It is composed of particles called grains having a particle size of 50 μm to 150 μm whose surface is covered with a skin layer mainly composed of cellulose or the like. Furthermore, this grain has a particle size of 0.5 μm or more.
It is composed of an aggregate of particles called 2.0 μm primary particles.

In order to produce a tube having excellent mechanical strength by extruding a vinyl chloride resin, the resin composition is sufficiently kneaded in an extruder to disintegrate the grain particles and to fuse the primary particles (hereinafter referred to as fusion). , "Gelling" and the degree of gelation as a whole
Call. ) Needs to be advanced.

[0006] Usually, gelation of a vinyl chloride resin is achieved mainly by shearing at a screw engagement portion using a twin screw extruder. However, since the vinyl chloride resin has the property of dechlorinating and decomposing due to excessive heat, when local heat generation such as shearing at the screw meshing portion accompanies, it partially partially gels before highly gelling. The problem that decomposition of the resin occurs may occur.

Japanese Patent Publication No. 3-48842 discloses a method for improving the kneading effect by providing a cutout in a screw flight of a compression section in which a screw groove depth changes in a plasticizing kneading zone of an extruder.

[0008]

[Problems to be solved by the invention]
In the method disclosed in Japanese Patent No. 8842, there is a problem that the load on the extruder increases with the improvement of the kneading effect, and as a result, the production speed must be reduced.

Accordingly, an object of the present invention is to solve the above-mentioned problems and achieve a kneading state in which the properties of the resin are maximized, thereby producing a resin tube having excellent mechanical properties without reducing productivity. And a device.

[0010]

Means for Solving the Problems The present inventors have studied to solve the above-mentioned problems, and as a result, when manufacturing a resin tube by extrusion molding, the resin solvent body in the shape of a tube flowing through a die is used. By applying micro-vibration having a component from the inner surface side to the thickness direction side, the present inventors have found an effect of promoting gelation (melting) or orientation of the resin composition, and have accomplished the present invention.

Specifically, by providing a tapered portion on the mandrel of the die and oscillating the tapered portion in the extrusion direction, a vibration having a component from the inner surface side of the tubular resin melt to the thickness direction side at the tapered portion. Could be applied.

Accordingly, the present invention relates to a method for producing a resin melt obtained by kneading a thermoplastic resin composition in an extruder according to claim 1, wherein the resin melt has a taper portion having a gradient of 10 degrees or more and less than 90 degrees and is extruded in the extrusion direction. A method for manufacturing a resin tube, wherein the resin tube is extruded from a die having a mandrel vibrating at a frequency of 10 kHz to 500 kHz and molded into a tube shape.

Further, according to the present invention, in claim 2, an extruder for kneading a thermoplastic resin composition and extruding a resin melt, and forming the resin melt extruded from the extruder into a tubular shape and extruding the same. In the apparatus for manufacturing a resin tube provided with a die, the die has a taper portion having a gradient of 10 degrees or more and less than 90 degrees, and a frequency of 10 kHz to 50 in the extrusion direction at the time of extrusion.
Provided is an apparatus for manufacturing a resin pipe, which is provided so as to vibrate at 0 kHz.

Hereinafter, the present invention will be described in more detail.

The tube forming die used in the present invention has a cylindrical mandrel called a mandrel for forming a tube shape mounted inside. The mandrel has a tapered portion, that is, a conically tapered shape. The shape does not necessarily have to be linearly tapered, but may be a curved shape. In addition, the gradient of the tapered portion is limited to 10 degrees or more and less than 90 degrees because the propagation component of vibration in the thickness direction of the melt decreases when the gradient becomes small. ~
It is preferable to set the range to 60 degrees.

The mandrel has a frequency of 10 kHz in the extrusion direction.
It is provided so as to vibrate at z to 500 kHz. When the vibration direction of the mandrel is perpendicular to the extrusion direction, the smoothness of the inner surface of the pipe may decrease and the structure becomes complicated. Therefore, the vibration direction is set to the extrusion direction (resin discharge direction). There is a need. Also, when the frequency of the vibration of the mandrel is low, there is a possibility that a problem of noise may occur. When the frequency of the vibration increases, the vibration may not be transmitted to the inside of the resin melt, and a desired effect may not be obtained.
limited to z to 500 kHz, preferably 15 kHz to
300 kHz, more preferably 17 kHz to 80 kHz
z.

In order to vibrate the mandrel at the desired frequency, it is necessary to design the material, shape and length of the mandrel so as to resonate at that frequency. The material of the mandrel is preferably a material having a small transmission loss of vibration at the molding temperature, and examples thereof include a titanium alloy, duralumin, and aluminum.

As a method of vibrating the mandrel in the pushing direction, a screw or the like is attached to the rear of the mandrel in such a direction as to vibrate the vibrator, which is a device (electroacoustic transducer) for converting high frequency power into mechanical vibration power, in the pushing direction. And supplying a high-frequency current to the vibrator. As a vibrator, a bolted Langevin type vibrator is generally used in which a piezoelectric material (barium titanate or lead zirconate titanate), which generates displacement and force when a voltage is applied, and a metal are tightened with a bolt and integrated. Is preferably used. As the high-frequency power supply for driving the vibrator, an oscillator including an oscillation circuit, a voltage amplifier, a power amplifier, an impedance matching circuit, and the like is generally used.

The thermoplastic resin composition used as a raw material in the present invention is not particularly limited, and vinyl chloride resins such as vinyl chloride resin and chlorinated vinyl chloride resin, polyethylene, polypropylene, polyamide, polyacetal, polyethylene terephthalate, ionomer resin And mixtures of these resins with fillers.

Further, within a range not to impair the object of the present invention,
If necessary, one or more of various additives such as stabilizers, lubricants, processing aids, impact modifiers, and pigments may be contained.

When the thermoplastic resin used is a vinyl chloride resin, the gelling effect is lost when the average amplitude in the extrusion direction at the tapered portion is small, and the resin may be decomposed when the average amplitude is large. 5μ
m to 50 μm, more preferably 10 μm to 30 μm.
μm.

When it is necessary to increase the amplitude of the vibration generated by the vibrator and transmit it to the mandrel, a cone (intermediate horn) that resonates at a desired frequency may be inserted between the vibrator and the mandrel. In addition, by attaching a flange to the node portion (portion where the displacement of vibration is 0) of the cone, the vibrator can be supported while eliminating the influence of the vibration on the mounting portion.

In the present invention, when the resin inlet of the die is located on the side surface of the die, a cylinder having a manifold on the outer periphery (hereinafter referred to as an auxiliary mandrel) may be attached so as to cover the mandrel near the resin inlet. preferable. By the auxiliary mandrel, the residence time distribution of the molten resin in the die can be made uniform, and a resin pipe having a uniform thickness can be formed.

The extruder used in the present invention is a screw extruder generally used in plastic molding, and is not particularly limited, but is a single screw extruder, a twin screw extruder, or the like. Examples include a multi-screw extruder having three or more screws, all of which are suitably used. In particular, when a vinyl chloride resin is used as the thermoplastic resin, a biaxially-rotating screw extruder having an excellent kneading effect is preferably used.

In the present invention, a shaping device, such as a forming die and a cooling water tank, may be provided as needed for cooling and shaping the pipe.

[0026]

According to the present invention, when extruding a thermoplastic resin composition into a tubular shape, a tapered portion is provided on a mandrel of a die, and the tapered portion is formed in the extrusion direction at a frequency of 10 kHz to 500 kHz.
By vibrating the resin, vibration having a component in the thickness direction is applied to the resin flowing in the die, and the kneading (gelling) of the resin composition can be promoted.

[0027]

FIG. 1 is a schematic configuration diagram showing an example of an embodiment of the present invention. The resin composition as a raw material is supplied to an extruder 2 via a hopper 1, where it is melt-kneaded. The extruder 2 is a biaxially different direction screw extruder in which two screws 19 having a plurality of screw flights 13 rotate in different directions. The resin melt obtained here is sent from the adapter 3 to the resin flow path 4 of the die 15, and the tapered portion 16 having a gradient of 45 ° as shown in FIG.
Vibration is applied from a mandrel 8 having a predetermined frequency and amplitude and vibrating in the extrusion direction. The resin melt is
Next, the resin is extruded at a predetermined discharge amount from the resin discharge port 6, and a resin tube 7 having a desired size is obtained.

The mandrel 8 is vibrated by the vibrator 11 through the cone 10 in the pushing direction. That is, the oscillator 1
2 (frequency 20 kHz, maximum output 3.6 kW), the vibration generated in the vibrator 11 by the high-frequency current
The beam is widened by the cone 10 and transmitted to the mandrel 8. A flange 18 is provided at a node portion of the cone 10 and supports the vibrator 11 by being connected to the cavity 5 of the die 15. An auxiliary mandrel 9 having a manifold 17 on the outer surface is attached to the outer periphery of the mandrel 8, so that the residence time distribution of the molten resin in the die 15 is made uniform. FIG. 2 also shows the fluctuation waveform of the vibration of the mandrel 8. The average amplitude in the extrusion direction at the tapered portion is, for example, 25 μm.

[0029]

The present invention will be described in more detail with reference to the following examples.

[Example 1] (Blend of raw materials) Vinyl chloride resin (degree of polymerization: 1000) 100 parts Organotin stabilizer 1.5 parts Calcium stearate 1 part Stearic acid 1 part Polyethylene wax 0.5 part

Using the apparatus shown in FIG. 1, the above raw material mixture was supplied from the hopper 1 and the barrel temperature was set to 175 from the front.
Extruder (φ = 50 ° C., 190 ° C., 190 ° C.)
mm, L / D = 30) 2, and the resin composition was melt-kneaded.
The melt is sent from the adapter 3 to the resin flow path 4 of the die,
Vibration was applied to the melt from a mandrel 8 vibrating in the extrusion direction at a frequency of 20 kHz and a maximum amplitude of 30 μm. Next, the resin was extruded from the resin discharge port 6 at a discharge rate of 100 kg / h, and a vinyl chloride resin pipe 7 having an outer diameter of 32 mm and an inner diameter of 25 mm was used.
I got The gradient of the tapered portion 16 of the mandrel 8 used in this embodiment is 45 degrees, and the average amplitude of the tapered portion 16 in the extrusion direction is 25 μm.

The obtained resin pipe was measured for Charpy impact strength using a Charpy impact tester in accordance with JIS K 7111. Table 1 shows the results.

Comparative Example 1 The procedure of Example 1 was repeated except that a mandrel 8 having a tapered portion 16 having a gradient of 5 ° as shown in FIG. 3 was used. The outer diameter was 32 mm and the inner diameter was 25 mm.
Was obtained. For the obtained resin tube, the Charpy impact strength was measured in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 2 A gradient of 45 ° as shown in FIG.
Using a mandrel 8 having a tapered portion 16 as described in Example 1, except that the average amplitude in the extrusion direction at the tapered portion 16 is 4 μm, a vinyl chloride resin tube 7 having an outer diameter of 32 mm and an inner diameter of 25 mm is obtained. Was. For the obtained resin tube, the Charpy impact strength was measured in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 3 The same procedure as in Example 1 was carried out except that the average amplitude in the extrusion direction of the tapered portion 16 of the mandrel 8 was changed to 60 μm by changing the shape of the cone 10, and the outer diameter was 32 mm and the inner diameter was 25 mm Was obtained. About the obtained resin tube, Example 1
The Charpy impact strength was measured in the same manner as described above, and the results are shown in Table 1. In addition, black carbide, which is considered to be a decomposition product of the resin, was attached to the inner surface of the obtained resin tube.

Comparative Example 4 The oscillation frequency of the mandrel 8 was changed to 600 by changing the oscillator 12 and the vibrator 11.
The same procedure as in Example 1 was carried out except that the frequency was set to kHz and the average amplitude in the extrusion direction of the tapered portion 16 became 5 μm, thereby obtaining a vinyl chloride resin tube 7 having an outer diameter of 32 mm and an inner diameter of 25 mm. About the obtained resin tube,
The Charpy impact strength was measured in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 5 The same procedure as in Example 1 was carried out except that the mandrel 8 was not vibrated, and the outer diameter was 32 m.
m, a vinyl chloride resin tube 7 having an inner diameter of 25 mm was obtained. For the obtained resin tube, the Charpy impact strength was measured in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 6 As shown in FIGS. 5 and 6,
An attempt was made in the same manner as in Example 1 except that the notch 14 was provided in the screw flight 13 of the plasticizing kneading zone of the screw 19 of the extruder 2 and that the mandrel 8 was not vibrated. Since the limit value was exceeded, the discharge rate was reduced to 70 kg / h, and a vinyl chloride resin tube 7 having an outer diameter of 32 mm and an inner diameter of 25 mm was obtained. For the obtained resin tube, the Charpy impact strength was measured in the same manner as in Example 1, and the results are shown in Table 1.

[0039]

[Table 1]

[0040]

As described above, according to the present invention, a resin tube having excellent mechanical properties without lowering the productivity can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of an apparatus for manufacturing a resin tube of the present invention.

FIG. 2 is a schematic diagram showing an example of a mandrel used in the present invention and a displacement waveform diagram in a vibration extruding direction.

FIG. 3 is a schematic diagram showing an example of a mandrel other than the present invention and a displacement waveform diagram in a vibration extruding direction.

FIG. 4 is a schematic diagram showing an example of a mandrel other than the present invention and a displacement waveform diagram in a vibration extrusion direction.

FIG. 5 is a schematic view showing an example of a plasticizing kneading zone of a screw of a conventional extruder.

FIG. 6 is a sectional view of the screw shown in FIG. 5;

[Description of sign]

 1: Hopper 2: Extruder 3: Adapter 4: Die resin flow path 5: Die cavity 6: Resin discharge port 7: Resin tube 8: Mandrel 9: Auxiliary mandrel 10: Cone 11: Vibrator 12: Oscillator 13: Screw Flight 14: Notch 15: Die 16: Taper 17: Manifold 18: Flange 19: Screw

Claims (2)

[Claims] 1. A resin melt obtained by kneading a thermoplastic resin composition with an extruder is provided with a taper having a gradient of 10 ° or more and less than 90 ° and a frequency of 10 kHz to 50 ° in the extrusion direction.
A method for manufacturing a resin tube, comprising: extruding from a die having a mandrel vibrating at 0 kHz to form a tube. 2. A resin pipe comprising: an extruder for kneading a thermoplastic resin composition to extrude a resin melt; and a die for extruding the resin melt extruded from the extruder into a tubular shape and extruding the same. In the manufacturing apparatus, the die has a gradient of 10 degrees or more and 9 degrees or more.
An apparatus for manufacturing a resin pipe, comprising: a tapered portion of less than 0 degrees, and provided so as to vibrate at a frequency of 10 kHz to 500 kHz in an extrusion direction during extrusion.