JPH0548169B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a synthetic resin composite pipe. Thermoplastic resin pipes such as polyvinyl chloride and polyethylene are widely used for construction and civil engineering works such as water and sewage pipes, electrical piping, and drainage pipes, as well as for agricultural purposes. However, these thermoplastic resin tubes are sensitive to heat and deform when exposed to high temperatures, and are also melted and burnt by flames. On the other hand, metal tubes commonly used for these applications have excellent heat and flame resistance, but have poor insulation properties, and in the event of a flame, they may damage the contents inside the tube, the tube support, or the surrounding area. It has the disadvantage of transmitting high heat and causing the spread of flame, being heavy, having poor machinability, and being corrosive. Therefore, it is conceivable to provide thermosetting resin pipes that are highly heat resistant, flame resistant, corrosion resistant, and heat insulating, and are also relatively lightweight, but conventional molding methods would be expensive and the physical properties would be poor. However, it has not been put to practical use in these applications due to some problems. In other words, long tubes of thermosetting resin are generally formed by plunger extrusion, but when using this method, the extrusion pressure in the mold section is high, and since it is intermittent extrusion, it is not uniform. It is difficult to obtain molded products, and productivity is low. For these reasons, a molding method using a die and screw-type extruder has been developed, but with this method, the resin tends to stagnate in the extrusion device, causing the curing reaction to proceed locally, or when the resin is exposed to slight pressure or pressure. There were problems such as the curing reaction progressing rapidly due to temperature changes, making it difficult to perform continuous and stable molding. In addition, when using any of the extrusion methods described above, only a tube with low strength in the circumferential direction is obtained, and as a result, it is weak against internal and external pressure and easily cracks in the axial direction of the tube when subjected to impact. There were practical problems such as: The reason for this is that in conventional extrusion methods, molten resin is guided into the mold and shaped and hardened while moving along the flow path within the mold, during which time the resin moves in the extrusion direction. In other words, it is thought that this is because only the tube axis direction exists, and the resin, filler, etc. are oriented in that direction. The present inventors have solved such problems and have achieved heat resistance,
As a result of various studies in order to obtain an inexpensive synthetic resin pipe that is lightweight and impact resistant with excellent flame resistance, corrosion resistance, etc., we have developed an extruded thermosetting resin pipe in which the resin and/or filler is oriented in irregular directions. However, it was discovered that the compressive strength in the axial direction and the direction perpendicular to the axis of the tube is well balanced, and as a result, it is strong against internal and external pressure and exhibits excellent properties against impact. The composite tube obtained by coating
The present invention was achieved by discovering that the material has significantly excellent heat resistance, flame resistance, and impact resistance. Using an extruder equipped with a screw having a feeding section, a compression section, a measuring section, and a smooth section, and a cylinder having a constant inner diameter, the resin is shaped in the gap between the screw smooth section and the inner wall of the cylinder. and/or the filling is oriented in an irregular direction, the ratio of the compressive strength in the direction perpendicular to the tube axis to the compressive strength in the direction of the tube axis is 0.4 to 1.5, and the breaking stress is 300 to 700 kg/
^This is a synthetic resin composite tube made by coating the surface of a thermosetting resin tube with a thermoplastic resin. The synthetic resin composite tube of the present invention is manufactured by extrusion molding, in particular, by using an extrusion molding machine with a built-in screw, and applying heat to a thermosetting resin tube that is shaped and hardened to the extent that it can maintain its own shape after extrusion at its tip. Manufactured by coating with plastic resin. For example, this method uses a screw with a smooth part at the tip, shapes the thermosetting resin in the smooth part to the extent that it can maintain its own shape, and then coats the surface with the thermoplastic resin. The specific method is to use a screw with a smooth part at the tip to shape the thermosetting resin to the extent that it can maintain its own shape in the smooth part, and then the thermosetting resin is shaped. The first method is to press-fit and extrude thermoplastic resin into the zone where the resin is to be applied, or similarly, use a screw with a smooth portion at the tip and apply thermosetting resin to the extent that it can maintain its own shape in the smooth portion. A second method can be adopted in which the molded material is shaped and extruded, and subsequently introduced into a mold of another extruder to be coated with a thermoplastic resin. The thermosetting resin tube that forms the inner layer of the composite tube of the present invention is formed by extrusion molding, particularly by using an extrusion molding machine with a built-in screw, and shaping and hardening it at its tip to the extent that it can maintain its own shape after extrusion. More preferably, it is produced by the method described in Japanese Patent Application No. 58-51526,
In this method, a screw having a smooth portion at the tip is used, and after extrusion, the material is shaped to the extent that it can maintain its own shape. In other words, the thermosetting resin material fed into the extruder is heated and melted while passing from the screw supply section to the compression section, passes through the measuring section, moves from the tip of the flight of the measuring section to a smooth part in a helical shape, and there it is transferred to the cylinder. Due to the frictional resistance with the inner wall, the gap created by the screw flight is narrowed and finally pressure fused. The resin is then hardened and shaped while traveling through the smooth section, and is extruded from the tip of the cylinder into a continuous tube. During this time, the resin moves while being subjected to shear in the direction generally along the screw groove from the supply section to the metering section, so the resin itself and the filler must be oriented in a particular direction with respect to the extrusion direction of the tube. After the resin is oriented in an irregular direction and transitions to a smooth part, the resin itself and the filling material are oriented in a well-balanced manner in the axial and circumferential directions of the tube, especially in the surface layer, as the curing progresses. It is considered that the compressive strength in the axial direction of the tube and in the direction perpendicular to the tube axis is better balanced. The orientation of the resin and filler in the tubes of the invention can be observed, for example, by electron microscopy. Figure 1 is an electron micrograph of a cross section in the tube axis direction of a phenolic resin tube extruded by a conventional extrusion method (plunger type), and Figure 2 is a cross section in the direction perpendicular to the tube axis. can be,
FIGS. 3 and 4 are electron micrographs of respective cross sections of a phenolic resin pipe, which is one of the thermosetting resin pipes of the present invention. In Figures 1 and 2, it is clear that the glass fibers are oriented in the direction of the tube axis, whereas in Figures 3 and 4, the fibers are specifically oriented in a certain direction. It can be seen that the particles are oriented irregularly without any distortion. Table 1 below shows the compressive strength in the direction perpendicular to the tube axis (A), the compressive strength in the tube axis direction (B), and A/
The measurement results of the ratio of B and the results of the water pressure test are listed. As can be seen from this table, the pipes made by the conventional method have a small A/B ratio of 0.37 and are prone to vertical cracking, whereas the pipes of the present invention have an A/B ratio of 0.4 to 1.5, for example.
More preferably, it is as large as 0.5 to 1.5, and it can be seen that it is strong against internal pressure without causing vertical cracks. The compressive strength in the tube axis direction mentioned above is JIS-K-
Compressive strength in the direction perpendicular to the pipe axis refers to the strength when the pipe breaks (including cracks) when tested according to Section 5.19.5 of 6911 (compressive strength test).
This indicates the strength of the pipe when it breaks when tested in accordance with Section 5.6 of JISK6741 (flattening test). The extruder used to mold the thermosetting resin tube of the present invention is not limited to a single-screw extruder, but also a twin-screw or multi-screw extruder, in which the tip ends in a single-screw extruder. Any extruder that is integrated into the shaft can be used. As for the internal structure of these extruders used in the present invention, there is no problem in providing a deaeration hole or a special kneading mechanism between the extruder supply section and the measuring section at the tip. A typical screw used for molding the thermosetting resin pipe of the present invention is a screw having a smooth portion 4 at the tip (hereinafter referred to as special screw) as shown in FIG. teeth,
For example, it includes a supply section 1, a compression section 2, and a measuring section 3.
The smooth section 4 may be of a type such that it starts from the end of the supply section as shown in Fig. 5, from the end of the compression section as shown in Fig. 6, or from the middle of the measuring section as shown in Fig. 7. . Further, the screw diameter of the smooth portion 4 can be adjusted by expanding or contracting it in accordance with the desired inner diameter of the molded product, separately from the diameter of the screw bottom of the portion having flights. L/D of special screw used in the present invention
is usually 7 to 40, preferably 10 to 35, more preferably 15 to 25, and the compression ratio is 1.0 to 5.0, preferably 1.2 to
4.0, more preferably 1.5 to 3.0, the length of the smooth part of the screw tip is 1 to 16D, preferably 2 to 3.0D.
It can be appropriately selected from the range of 12D, more preferably 2 to 9D. A normal full-flight screw without a smooth portion at the tip cannot produce a pipe-shaped molded product, but only a spiral-shaped molded product. Furthermore, if the length of the smooth portion is less than 1D, the molded product obtained after extrusion will be deformed, making it difficult to continuously obtain a good molded product. Furthermore, if the length of the smooth portion is 16D or more, the molding pressure will be high and it is not practical in terms of the mechanical strength of the extruder. The compression ratio of the screw and the length of the smooth portion are subject to various restrictions depending on the gap between the screw and the barrel in the smooth portion, in other words, the thickness of the molded product, the extrusion speed, and the characteristics of the material used. As for the compression ratio of the screw and the length of the smooth portion, the larger or smaller the screw, the larger or smaller the back pressure applying function. If the back pressure is too large, excessive kneading will occur in the portions having flights, resulting in excessive heat generation and hardening of the material, which is undesirable. On the other hand, if the back pressure is too low, compression filling and kneading of the material will become insufficient, which is also not preferred. Adequate back pressure is necessary for compaction filling and proper kneading of the material. That is, in order to achieve stable extrusion and a good product, an appropriate compression ratio of the screw and a suitable length of the smooth portion are required. The larger or smaller the gap between the screw and the barrel in the smooth part, the lower or higher the extrusion speed, the lower or higher the viscosity of the material used, the lower or higher the curing speed of the material used, the lower or higher the extrusion speed. , the compression ratio of the screw and the length of the smooth part need to be large or small. In manufacturing the synthetic resin composite pipe of the present invention, the temperature settings of each part of the extruder for molding the thermosetting resin are determined by the characteristics of the material used, the compression ratio of the screw, the gap between the screw smooth part and the barrel, Although it naturally varies depending on the combination of the length of the smooth part and the extrusion speed, etc., the temperature setting of the compression part, metering part, and cylinder part corresponding to the smooth part of the screw is usually in the range of 50 to 200 degrees Celsius, preferably 60 to 150 degrees Celsius. . Therefore, if the set temperature is below 50℃, the curing reaction of the resin will not proceed sufficiently, making it difficult to obtain a good molded product.On the other hand, thermosetting resins commonly used at temperatures up to 200℃ tend to be difficult to obtain. There is no need to heat it any further as it will harden with heat. The thermosetting resin tube formed by the above method is coated with a thermoplastic resin by, for example, the first method or the second method described above to obtain a composite tube. In the first method, the structure of the part for coating the thermoplastic resin around the thermoplastic resin pipe and the extruder for thermoplastic resin may be those commonly used for coating thermoplastic resin. However, the position of the thermoplastic resin supply section is from the point where the smooth part of the screw of the extruder that molds the thermoplastic resin starts.
It is necessary that the distance is 1D or more, and the distance is preferably selected from a range of 2D to 12D, more preferably 2D to 9D. In this method, the thermosetting resin is spiral-shaped and moves from the measuring section to the smooth section, and then fuses to each other.
form a tube. Therefore, if the thermoplastic resin is supplied within 1D from the starting point of the smooth portion, it is not preferable because gaps tend to remain in the inner thermosetting resin layer, resulting in non-uniformity. In addition, the length of the smooth portion after the thermosetting resin layer and the thermoplastic resin merge has a length necessary for shaping the thermosetting resin to the extent that it can maintain its own shape after extrusion, It is sufficient that the length is sufficient to cover the thermoplastic resin, and is 0 to 15D, preferably 0.
Appropriately selected from the range of ~7D. In the second method described above, the thermosetting resin is extruded by an extruder for extruding the thermosetting resin, and then
The base needs to be shaped to the extent that it can maintain its own shape, and the length of the smooth part at the tip of the screw for this purpose can be appropriately selected from the range of 1 to 16D, preferably 2 to 12D, and more preferably 2 to 9D. can. The extruded thermosetting resin tube is then introduced into the mold section of a thermoplastic resin extruder having a cross-headed die, either as it is or with an appropriate gap, and is coated with a thermoplastic resin. . As a thermoplastic resin extruder for coating this thermoplastic resin, a conventional thermoplastic resin extrusion molding extruder having a crosshead die capable of coating a thermoplastic resin of a predetermined thickness can be used. In either of the first method and the second method described above, the extrusion conditions for the thermoplastic resin can be those normally applied to the thermoplastic resin used. The apparatus suitable for the first manufacturing method of the synthetic resin composite pipe described above includes a screw consisting of a supply section, a compression section, a metering section, and a smooth section, and a heat control mechanism corresponding to the supply section, compression section, and metering section. and a cylinder part having a heat supply function corresponding to the smooth part having a diameter equal to or different from the final starieux diameter D of the measuring part, and by the smooth part and the corresponding cylinder part. A screw-type extrusion molding device for thermosetting resin that accelerates the curing reaction in the gap formed and shapes the resin to the extent that it can maintain its own shape after extrusion, and a position that transitions to the smooth portion of the extrusion molding device. An example of this is an apparatus for producing a synthetic resin composite tube, which is comprised of a screw-type extrusion molding apparatus for thermoplastic resin, which has a thermoplastic resin supply section on the inner circumferential portion of the cylinder corresponding to a position on the screw tip side of 1D or more. The apparatus suitable for the second manufacturing method is as follows:
A screw consisting of a feeding section, a compression section, a metering section and a smooth section, a cylinder section having a thermal control mechanism corresponding to the feeding section, the compression section and the metering section, and a diameter equal to or different from the final screw diameter of the metering section. The cylinder part has a heat supply function corresponding to the smooth part, and the curing reaction is promoted in the gap formed by the smooth part and the corresponding cylinder part to the extent that it can maintain its own shape after extrusion. A device for manufacturing synthetic resin composite tubes is comprised of a screw-type extrusion molding device for thermosetting resin, which is designed to shape the thermosetting resin up to Can be mentioned. The apparatus for manufacturing a thermosetting resin composite pipe described above can be effectively used for manufacturing a composite pipe by employing the first method and the second method described above. Examples of thermosetting resins used in the present invention include phenolic resins, melamine resins, urea resins, unsaturated polyester resins, epoxy resins, silicone resins, allyl resins, xylene resins, and aniline resins. Among them, phenolic resin, melamine resin and urea resin are preferably used. The thermosetting resin used in the present invention may contain fillers, mold release agents, thickeners, colorants, dispersants, blowing agents, or polymerization initiators commonly used in the molding of thermosetting resins, as necessary. A curing agent, a curing accelerator, a polymerization inhibitor, etc. can be added. Furthermore, other types of polymers or organic or inorganic fibrous materials such as glass can also be added. Examples of the thermoplastic resin used in the present invention include polyethylene, polypropylene, polyvinyl chloride, polystyrene, polycarbonate, acrylonitrile-butadiene-styrene copolymer, polymethyl acrylate, and polyethylene terephthalate. Additives commonly used in the molding of thermoplastic resins, such as stabilizers, fillers, processing aids, antioxidants, reinforcing agents, colorants, and lubricants, are added to these thermoplastic resins as necessary. can do. FIG. 8 is a plan view showing an example of a preferred apparatus for carrying out the first method of coating a thermosetting resin pipe with a thermoplastic resin in the present invention, including a perspective view of the screw portion. . FIG. 9 is a plan view showing an example of a preferred apparatus for carrying out the second method of coating thermoplastic resin. In FIG. 8, the thermosetting resin material supplied from the hopper 5 is heated and melted by the heater 7 in the cylinder 6, moves from the tip of the flight of the screw 8 to the smooth part 4 in a helical shape, and moves to the smooth part 4 in the cylinder. Due to the frictional resistance, the gap created by the screw flight is narrowed and finally pressure fused. The fusion resin is then shaped while moving through the screw smooth portion to the extent that it can maintain its own shape after extrusion. During this time, the thermosetting resin tube 11 is coated with the thermoplastic resin press-fitted from the extruder 9 for thermoplastic resin through the supply section 10, and the thermosetting resin tube 11 is turned into a composite tube 13 coated with the thermoplastic resin 12. Continuously extruded. In FIG. 9, the thermosetting resin material supplied from the hopper 5 is heated and melted by the heater 7 in the cylinder 6, moves from the tip of the flight of the screw 8 to the smooth part 4 in a helical shape, and then moves to the smooth part 4 in the cylinder. Due to the frictional resistance, the gap created by the screw flight is narrowed and finally pressure fused. Next, the fusion resin is shaped to the extent that it can maintain its own shape after extrusion while moving through the screw's smooth section, and is extruded from the tip of the cylinder as a continuous thermosetting resin tube 11. The extruded thermosetting resin tube is then introduced into the die of a thermoplastic resin extruder 9 equipped with a crosshead die 14, coated with thermoplastic resin, and extruded into a composite tube. Usually, in the extrusion molding method of thermosetting resin,
The resin heated and melted in the cylinder is introduced into the mold via an adapter and shaped into the final shape. During this process, the flow of resin is constricted by the adapter and flows around the mandrel fixed by the spider. Because the flow path of the resin changes in a complicated way, such as when the resin is re-expanded, it is easy for the resin to stagnate, causing the curing reaction to proceed locally, or to cause the curing reaction to occur rapidly with a slight change in pressure or temperature. causing problems such as In addition, in order to overcome the resistance caused by the complicated flow paths and extrude the resin while preventing stagnation, a large extrusion pressure is required and a special extrusion device is required. However, when using such a molding method, the extrusion speed is about 30 cm/min in height, and it is difficult to obtain a product with good roundness and thickness distribution. On the other hand, according to the method and apparatus described above, the smooth part of the screw and the cylinder part in that part play the role of a mold, and the resin flow path is only the gap between the cylinder and the screw, so that the resin does not accumulate. It does not cause any localized curing reactions or rapid curing reactions due to changes in pressure and temperature. The screw of the present invention has an open tip,
Since it has a pressure increasing function part and a back pressure applying function part over its entire length, the forces of the two cancel each other out, and the force applied to the thrust bearing of the screw is essentially smaller than that in a general molding method using a screw and a mold. In addition, since the smooth part of the screw of the present invention, which corresponds to the mandrel in the mold in general molding methods, is rotating, the frictional resistance between the hardened resin and the metal part is relatively small, and the extrusion pressure is lower than that of normal screw extrusion. The pressure obtained by the machine is sufficient. When such a method of the present invention is used, an extrusion speed of, for example, 80 cm/min can be easily obtained. According to the above-mentioned method and apparatus, the thermosetting resin can be molded continuously and stably and with high productivity using the extrusion pressure obtained by a conventional screw extruder, and the thermoplastic resin can be easily coated. Therefore, it is possible to easily manufacture a composite pipe in which the surface of a thermosetting resin is coated with a thermoplastic resin. The composite tube obtained by the above-mentioned method is cured and shaped by controlling the molding conditions to a point where the thermosetting resin is sufficiently controlled to maintain its own shape at the time the thermosetting resin is extruded. Since curing is sufficiently completed by coating the thermoplastic resin at a temperature higher than the above temperature, phenomena such as deformation, warping, bending, and swelling do not occur. In addition, the resulting composite tube has excellent heat resistance, flame retardancy, and impact resistance, as the inner layer is made of a thermosetting resin with excellent heat resistance and flame retardancy, and the outer layer is made of a thermoplastic resin with excellent impact resistance. It becomes something. As explained above, according to the above-mentioned method and apparatus, a synthetic resin composite pipe having excellent heat resistance, flame retardance, and impact resistance can be easily manufactured with high productivity. The synthetic resin composite pipe of the present invention described above has excellent heat resistance, flame retardance, and impact resistance, and is therefore useful as, for example, electrical equipment or construction and civil engineering materials. The present invention will be further explained below using reference examples and production examples. Reference example 1 An extruder with a diameter of 30 mm and L/D = 22 has a diameter of 26 mm at the tip that follows the measuring section where the screw bottom diameter is 26 mm.
A screw with a compression ratio of 2.0 and a smooth part with a length of 105 mm (3.5D) was used, and the pipe was made using phenol resin (manufactured by Nippon Oil Seal Co., Ltd., trade name Logiyas RX-6684) as the molding material. Continuously extruded. The temperature of each part of the cylinder is set to C ₁ (0-2D)...Water-cooled C ₂ (3D-10D)...80℃ _C3 (11D-18D)...100℃ _C4 (19D-22D)...120℃ Then, extrusion molding was performed at a screw rotation speed of 35 rpm to obtain a pipe with an outer diameter of 30 mm and a wall thickness of 2.0 mm. Reference Example 2 A pipe was extrusion-molded using the same extrusion apparatus as in Reference Example 1, using a phenol resin (manufactured by Nippon Gosei Kako Co., Ltd., trade name: Nikalite 950-J) as a molding material. The temperature of each part of the cylinder is C ₁ = water cooling, C ₂ = 80
℃, C ₃ = 110℃, C ₄ = 120℃, molding was performed under the conditions of screw rotation speed 35 rpm, outer diameter 30 mm,
A pipe with a wall thickness of 2.0 mm was obtained. Reference Example 3 Using the same extrusion apparatus as in Reference Example 1, a pipe was extrusion-molded using phenol resin (manufactured by Sumitomo Bakelite Co., Ltd., trade name PM-795J) as a molding material. The temperature of each part of the cylinder is C ₁ = water cooling, C ₂ = 80℃,
Molding was carried out under the conditions of setting C ₃ = 105°C and C ₄ = 120°C and a screw rotation speed of 35 rpm to obtain a pipe with an outer diameter of 30 mm and a wall thickness of 2.0 mm. Reference example 4 Using an extruder with a diameter of 40 mm and L/D = 24, the diameter of the bottom of the screw is 35 mm, and the diameter is
Using a screw with a 35mm long 3D smooth part,
A pipe was extrusion molded using a phenol resin (manufactured by Sumitomo Bakelite Co., Ltd., trade name PM-795J) as a molding material. The temperature of each part of the cylinder is C ₁ = (0~
2D) = water cooling, _C2 (3~10D) = 60℃, _C3 (11~16D)
= 80℃, C ₄ (17~20D) = 110℃, C ₅ (21~24D) =
Set at 120℃, screw rotation speed 25rpm, outer diameter 40
A pipe with a wall thickness of 2.5 mm was obtained. Reference Example 5 Using the same extrusion equipment as Reference Example 1, melamine resin (manufactured by Otalite Co., Ltd., product name ON) was used as the molding material.
-600) was used to continuously extrude the pipe. The temperature of each part of the cylinder is C ₁ = water cooling, C ₂ = 85℃,
Molding was carried out under the conditions of setting C ₃ = 115°C and C ₄ = 130°C and a screw rotation speed of 35 rpm to obtain a pipe with an outer diameter of 30 mm and a wall thickness of 2.0 mm. Evaluation Results: The results of the compressive strength (direction perpendicular to the pipe axis, direction of the pipe axis, and ratio thereof) and water pressure test of the pipe obtained in the above manufacturing example were as shown in Table 1. Manufacturing example 1 A water cooling jacket is provided at a length of 2D from the bottom of the hopper, followed by thermal control devices at each section of 3 to 9D, 10 to 15D, and 16 to 19D, followed by a thermoplastic jacket at a position 2D from the tip. A coating device (length:
Extruder (A) having a cylinder with a diameter of 40 mm and L/D = 24 (including the coating device part), with a diameter of 35 mm at the feed section 3D, a compression section 12D and the screw bottom.
A screw with a compression ratio of 1.8 (B) that has a smooth part with a diameter of 35 mm and a length of 5 D following a measuring part with a length of mm length 4D, and a screw with a compression ratio of 2.5 inside, a diameter of 30 mm L / D =
A composite tube was formed using a 22 extruder (C). The extruder (C) is connected to the coating device part of the extruder (A) equipped with a screw (B), and the extruder (A) is used as a molding material using phenol resin (manufactured by Sumitomo Bakelite Co., Ltd., trade name:
PM-795J), polyvinyl chloride compound (manufactured by Mitsui Toatsu Chemical Co., Ltd., trade name Viniclon) is used in the extruder (C).
EREK-1015), and _the extruder (A)
2D) = water cooling, _C2 (3~9D) = 80℃, _C3 (10~15D) =
95℃, _C4 (16~19D) = 110℃, coating equipment part (20~
24D) = 180℃, screw rotation speed 25rpm, extruder
(C) is _C1 (0~2D) = water cooling, _C2 (3~9D) = 150℃,
Extrusion was performed under the conditions of C ₃ (10 to 16D) = 170℃, C ₄ (17 to 22D) = 175℃, adapter = 180℃, screw rotation speed 45 rpm, and the inner layer was a phenolic resin with a diameter of 40 mm and a wall thickness of 2.5 mm. A composite tube with an outer diameter of 41.5 mm and a wall thickness of 4 mm was obtained, the outer layer of which was made of polyvinyl chloride resin with a diameter of 41.5 mm and a wall thickness of 1.5 mm. Manufacturing example 2 A water cooling jacket is provided at a length of 2D from the bottom of the hopper, followed by 3~10D, 11~16D, 17~20D and
Caliber 40mm with thermal control device in each part of 21~24D
With an extruder having L/D=24 cylinders,
Supply section 3D, compression section 15D and screw bottom diameter 35mm, following measuring section with length 3D, diameter 35mm, length
Using a screw with a 3D smooth part, melamine-phenol resin (Matsushita Electric Works Co., Ltd.) was used as the molding material.
The pipe was extruded using a product manufactured by ME-A (trade name: ME-A). The temperature of each part of the cylinder is C ₁ (0 to 2D) = water cooling,
C ₂ (3~10D) = 60℃, C ₃ (11~16D) = 85℃, C ₄
(17~20D) = 120℃, C ₅ (21~24D) = 130℃, screw rotation speed 25rpm, outer diameter 40mm wall thickness 2.5mm
extruded the pipe. Continuing this pipe as it is, it has a diameter of 30 with a screw with a compression ratio of 3.0.
It was introduced into a crosshead die glued to an extruder with mmL/D=22, and the temperature settings were C ₁ = 180°C, C ₂ =
Polypropylene resin (manufactured by Mitsui Toatsu Chemical Co., Ltd., trade name: Mitsui Noprene BEB-US) under the conditions of 210℃, C ₃ = 220℃, die = 220℃, and screw rotation speed 62 rpm.
is coated with a wall thickness of 1.5mm, and the inner layer has an outer diameter of 40mm and an inner thickness of 2.5mm.
melamine-phenolic resin, outer layer has an outer diameter of 41.5
A composite tube made of polypropylene resin with an outer diameter of 41.5 mm and a wall thickness of 4 mm was obtained. Comparative Example 1 Using the 40 mm extruder and screw used in Example 2, extrusion molding was performed using phenol resin (manufactured by Sumitomo Bakelite Co., Ltd., trade name PM795J) as a molding material. The temperature of each part of the cylinder is C ₁
= water cooling, C ₂ = 60°C, C ₃ = 80°C, C ₄ = 110°C, C ₅ =
Molding was carried out at a temperature of 120°C and a screw rotation speed of 25 rpm to obtain a phenol pipe with an outer diameter of 40 mm and a wall thickness of 2.5 mm. Table 2 shows the performance measurement results of the tubes obtained in each Example and Comparative Example. These results show that the synthetic resin composite pipe of the present invention has excellent heat resistance, flame resistance, and impact resistance.

【table】

【table】

【table】 [Brief explanation of drawings]

Figures 1 and 2 are electron micrographs showing the shape of the filled fibers in the cross section of a phenolic resin tube extruded by a conventional extrusion method, in the tube axis direction and in the direction perpendicular to the tube axis, respectively. , 3 and 4 are electron micrographs showing the shape of each fiber of the phenolic resin tube forming the inner layer of the synthetic resin composite tube of the present invention. Moreover, FIGS. 5, 6, and 7 are side views showing one example of the screw used in the present invention. FIG. 8 is a plan view showing one example of an apparatus preferable for coating a thermoplastic resin pipe on a thermosetting resin pipe in the present invention, and FIG. 9 is a plan view showing another example. . 1... Supply section, 2... Compression section, 3... Measuring section,
4...Smooth part, 5...Hopper, 6...Cylinder, 7...Heater, 8...Screw, 9...
Extruder for thermoplastic resin, 10...Thermoplastic resin supply section, 11...Thermosetting resin tube, 12...Thermoplastic resin layer, 13...Composite tube, 14...Crosshead die.

Claims (1)

[Claims] 1 Using an extruder equipped with a screw having a feeding section, a compression section, a measuring section, and a smooth section, and a cylinder having a constant inner diameter, shaping is carried out in the gap between the screw smooth section and the inner wall of the cylinder, and The resin and/or filler is oriented in irregular directions, the ratio of the compressive strength in the direction perpendicular to the tube axis to the compressive strength in the tube axis direction is 0.4 to 1.5, and the breaking stress is 300 to 700 kg/
A ^synthetic resin composite tube made by coating the surface of a thermosetting resin tube with a thermoplastic resin.