JPH09222185A - Composite pipe and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite pipe having excellent heat insulating and temperature holding functions without the occurrence of any thermal deformation in a coated layer or the absorption of water from a surface even when it is used in a high temperature and manufacture thereof. SOLUTION: A composite pipe 1 is constructed in such a manner that a coated layer 12 composed of a polyvinyl chloride resin foaming body is provided in the outer peripheral surface of a pipe main body 11 made of a polyvinyl chloride resin, the coated layer 12 is composed of a foamed inner layer part 121 and a substantially non-foamed surface layer part 122 formed in its outer periphery and the inner layer part 121 and the surface layer part 122 are integrally formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has excellent quality characteristics such as heat insulation, heat retention, and heat distortion resistance in which a coating layer made of foam is formed on the outer peripheral surface of a pipe body used for fluid transfer. And a manufacturing method thereof.

[0002]

2. Description of the Related Art Plastic pipes are widely used for transporting liquids, solids and gases. Particularly, vinyl chloride resin pipes are used for various transport pipes including water and sewer pipes.
Alternatively, it is widely used as a material for a heat insulating / heat insulating vip when transferring a high temperature fluid such as a water supply / drain pipe in a public bath or a hot spring area. In this case, in order to suppress the temperature drop during the transfer and protect the burn and the like due to the contact, it is usual to coat the outer peripheral surface of the pipe with a heat insulating / heat insulating material made of a synthetic resin foam.

For example, in Japanese Unexamined Patent Publication No. 3-122323, indoors in which an outer peripheral surface of a water supply hot water supply pipe made of synthetic resin is covered with a synthetic resin foam and an outer sheath made of synthetic resin is arranged on the outer peripheral surface of the pipe. It describes the piping materials. However, in the case where the heat insulating pipe is wound around the heat insulating material for construction, the heat insulating pipe and the heat insulating material are usually constructed separately, so that there is a problem that the construction takes time and labor.

Further, in Japanese Unexamined Patent Publication No. 5-96599, an adhesive is applied to a thermoplastic elastomer tube that has been once molded, and then a soft thermoplastic resin layer is extruded on the outer peripheral surface of the tube using a crosshead die. A method of manufacturing a composite tube by molding to form a coating layer is disclosed. In this case, even if a foam having a high expansion ratio is used for the coating layer, since it is free foaming, there is a problem in that it absorbs water from the outer surface of the foamed resin layer or becomes soft and deforms when used in a high temperature environment. Can be mentioned.

Further, Japanese Patent Application Laid-Open No. 56-155727 discloses a manufacturing method for obtaining a composite pipe by integrally laminating a coating layer made of a foam on the outer peripheral surface of a pipe body by a coating extrusion molding method. Has been done.

As one of the disclosed techniques, there is shown a method of coating a molten resin for molding a coating layer and a molten resin for molding a pipe body in a molten state in one mold. In this case, Since it is difficult to control the outer diameter of the pipe body and the pipe body and the coating layer are heat-sealed, the interface between them is firmly adhered, and the coating layer is used when connecting such composite pipes with a joint. It took a long time to peel off, and it was difficult to connect the composite pipes with each other by a joint.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, has no thermal deformation of the coating layer even when used at high temperature and absorbs water from the surface, is excellent in heat insulation and heat retention function, An object of the present invention is to provide a composite pipe having excellent dimensional accuracy of the main body and excellent workability, and a method for manufacturing the same. Or, in addition to the above object, to provide a composite pipe having an interfacial adhesiveness between the pipe body and the coating layer that allows manual peeling, and particularly excellent in workability, or in addition to the above object, a coating layer It is an object of the present invention to provide a composite pipe having excellent heat resistance, particularly, the heat deformation resistance of the coating layer.

[0008]

The invention according to claim 1 of the present application (hereinafter referred to as the present invention 1) is a coating of a vinyl chloride resin foam on the outer peripheral surface of a pipe body made of a vinyl chloride resin. A composite pipe provided with a layer, wherein the coating layer comprises a foamed inner layer portion and a substantially non-foamed surface layer portion formed on the outer periphery thereof, and the inner layer portion and the surface layer portion are integrated. It is a composite pipe formed by.

The invention according to claim 2 of the present application (hereinafter referred to as the present invention 2) is a composite in which a coating layer made of a vinyl chloride resin foam is provided on the outer peripheral surface of a pipe body made of a vinyl chloride resin. A pipe, wherein the coating layer comprises a foamed inner layer portion and a substantially non-foamed surface layer portion formed on the outer periphery thereof, and the inner layer portion and the surface layer portion are integrally formed, The tensile shear strength between the pipe body and the coating layer is 0.
It is a composite pipe of 001 to 0.3 kg / cm ² .

The invention according to claim 3 of the present application (hereinafter referred to as the present invention 3) is the composite pipe according to the present invention 1 or 2, wherein the pipe body is made of a chlorinated vinyl chloride resin.

The invention according to claim 4 of the present application (hereinafter referred to as the present invention 4) is obtained by extruding a vinyl chloride resin in a molten state by a first extruder and then curing the resin to continuously form a pipe body. The pipe body is sequentially introduced into the pipe body passage of the crosshead die, and the meltable foamable vinyl chloride resin is supplied to the crosshead die by the second extruder in the coating resin flow passage of the crosshead die. In the subsequent sizing die for the selka process, the expandable vinyl chloride resin was extruded from the coating resin flow path, foamed so as to bulge in the inner diameter direction, and the outer peripheral surface of the pipe body that passed through the pipe body passage In addition, it is a method for manufacturing a composite pipe in which a coating layer is sequentially formed.

In the present invention 1, the invention 2, and the invention 4, as the vinyl chloride resin forming the pipe body,
Other than chlorinated vinyl chloride resins, for example, homopolymers of vinyl chloride monomers, copolymers of vinyl chloride monomers and polymerizable monomers other than vinyl chloride monomers, other than vinyl chloride resins For example, a graft copolymer obtained by grafting a vinyl chloride monomer onto the above polymer is used.

In the above and the present invention 3, as the chlorinated vinyl chloride resin, a chlorinated vinyl chloride resin or a mixture with other vinyl chloride resin is used. The chlorinated vinyl chloride resin is a vinyl chloride resin obtained by post-chlorinating a vinyl chloride resin by a dry method, a wet method or the like, and one of its features is that it is superior in heat resistance to the vinyl chloride resin. For the subsequent chlorination, the degree of polymerization is usually 800 to 120.
About 0 vinyl chloride resin is used.

In the present inventions 1 to 4, the vinyl chloride-based resin forming the coating layer may be any as long as it has been conventionally used as a raw material for foamed molded articles. For example, vinyl chloride monomer. Homopolymers, copolymers of vinyl chloride monomers and polymerizable monomers other than vinyl chloride monomers, graft polymers obtained by grafting vinyl chloride monomers onto polymers other than vinyl chloride resins , Chlorinated vinyl chloride resins, mixtures of these resins and the like are used.

By the way, in order to form a coating layer having an inner layer portion foamed from a vinyl chloride resin, a foaming agent such as a pyrolytic foaming agent or a solvent type foaming agent is added to the vinyl chloride resin. Stuff used.

Examples of the heat-decomposable foaming agents include heat-decomposable inorganic foaming agents such as sodium bicarbonate, ammonium bicarbonate and ammonium carbonate, nitroso compounds such as N, N'-dinitrosoterephthalamide, azodicarbonamide, and the like.
Examples thereof include thermal decomposition type organic foaming agents such as azo compounds such as azobisisobutyronicryl, sulfonyl hydrazide compounds such as benzenesulfonyl hydrazide and toluene sulfonyl hydrazide, and the like.

Examples of the solvent-type foaming agent include alcohols such as methanol and ethanol. These thermal decomposition type or solvent type foaming agents may be used alone or in combination of two or more kinds.

The chlorinated vinyl chloride resin or vinyl chloride resin forming the pipe body and the vinyl chloride resin forming the coating layer to which a foaming agent has been added may be further heated as necessary. Stabilizers, processing aids, lubricants, impact modifiers,
Fillers, antioxidants, ultraviolet absorbers, light stabilizers, pigments and the like may be added as appropriate.

There are several methods for molding such a coating layer, and for example, there is a Celka process which is a kind of low foaming extrusion molding method of synthetic resin.

The cerca process referred to in the present invention is a kind of synthetic resin low foaming extrusion molding method developed by Eugene Coulman of France, in which a special cerca process sizing die (commonly known as "selca process" It is characterized by using a device that is directly connected to the forming tube.

The foam obtained when this selka process is adopted is composed of a foamed inner layer portion and a substantially non-foamed hard surface layer portion (= skin, commonly known as "selka layer") formed on the outer periphery thereof. Is formed by. Therefore, the specific gravity of the surface layer portion is large and that of the inner layer portion is small, and the inner layer portion and the surface layer portion are firmly integrated.

The term "substantially non-foamed" as used herein means a so-called low foaming ratio in which the hardness is high and water absorption hardly occurs from a completely non-foamed state. Further, a clear boundary may or may not be formed between the inner layer portion and the surface layer portion, and has a continuous structure in which the foaming ratio changes sequentially from the inner layer portion to the surface layer portion. It may be.

The thickness of the coating layer in the present invention is not particularly limited and may be appropriately set depending on the type of fluid to be transferred, temperature, flow rate, etc. However, if the thickness of the surface layer is too thin, Since the heat distortion resistance decreases, it is preferable that the thickness is at least 0.2 mm or more.

In order to provide the coating layer on the outer peripheral surface of the pipe body, there is a method of forming the coating layer separately and then inserting the pipe body into the coating layer material. In this case, it is preferable that the pipe body is a molded body having a heat-expanding property, an adhesive is applied to the surface of the pipe body in advance, and the heating fluid is flowed into the pipe body after being inserted into the coating layer material. There is a method of heating and expanding the diameter to bring it into close contact with the coating layer material.

As another method, there is a method in which the extrusion molding of the pipe body and the formation of the coating layer by the Celka process method are connected as in the present invention 4.

In the second aspect of the present invention, the tensile shear strength between the pipe body and the coating layer needs to be 0.001 to 0.3 kg / cm ² , and when the tensile shear strength is in this range, the coating layer is easily formed on the pipe body. The pipe bodies can be easily peeled off or the pipe body and the peeling layer can be easily displaced from each other, so that the pipe bodies can be easily connected to each other during construction.

In the present invention 2, the term “tensile shear strength” means that 5 pieces of each test piece as shown in FIG. 5 are prepared from a composite pipe and left in a thermostatic chamber at 23 ° C. for 48 hours and then at 23 ° C.
Was pulled at a speed of 500 mm / min, the tensile shear strength at the time of breaking of the interface was measured by an autograph, and it was calculated as the average value of the five measured values obtained.

(Function) In the composite pipe of the present invention 1, since the coating layer made of foam is provided on the outer peripheral surface of the pipe body made of vinyl chloride resin, the high temperature transferred due to the presence of the coating layer. The fluid is kept warm and the outside is insulated.

The coating layer is composed of an inner layer portion made of foam and a substantially non-foamed surface layer portion formed on the outer periphery of the inner layer portion. Since both are integrally formed, the inner layer portion is formed by the surface layer portion. Is reinforced to prevent the inner layer portion from being thermally deformed or peeled off over time, and imparts scratch resistance to the surface of the composite pipe.

Further, since the surface layer portion and the inner layer of the coating layer can be formed by extrusion molding, it is possible to adopt the selka process method or the extrusion coating molding method, and the surface layer portion and the inner layer portion of the coating layer are integrated. The formed product can be continuously molded, and the productivity of producing the coating layer is improved.

In the composite pipe of the second aspect of the present invention, since the coating layer made of foam is provided on the outer peripheral surface of the pipe body made of vinyl chloride resin, the presence of the coating layer keeps the transferred high temperature fluid warm. In addition, it is provided with a heat insulating property to the outside. Further, the covering layer is composed of an inner layer portion made of foam and a substantially non-foamed surface layer portion formed on the outer peripheral surface thereof, and since both are integrally formed, the inner layer portion is reinforced by the surface layer portion. Thus, the inner layer portion is prevented from being thermally deformed or peeled off with the passage of time, and the composite pipe surface is provided with scratch resistance.

Further, since the surface layer portion and the inner layer of the coating layer can be formed by extrusion molding, it is possible to adopt a selka process method or an extrusion coating molding method, and the surface layer portion and the inner layer portion of the coating layer are integrated. The formed product can be continuously molded, and the productivity of producing the coating layer is improved.

Further, since the tensile shear strength between the pipe body and the coating layer is 0.001 to 0.3 kg / cm ² , the interfacial adhesive strength between the pipe body and the coating layer is adjusted to the extent that manual peeling is possible. It was done.

In the composite pipe of the third aspect of the present invention, since the covering layer made of foam is provided on the outer peripheral surface of the pipe body made of chlorinated vinyl chloride resin, the pipe body in direct contact with the high temperature fluid is heat resistant. By adopting excellent chlorinated vinyl chloride resin, the heat distortion resistance is improved compared to that made of vinyl chloride resin, and the presence of the coating layer keeps the high temperature fluid to be transferred warm and provides heat insulation to the outside. Is provided.

The method for producing a composite pipe according to the fourth aspect of the present invention is the first
A molten vinyl chloride resin is extruded by an extruder and then cured to continuously form a pipe body, and the resulting pipe body is sequentially introduced into the pipe body passage of the crosshead die, and the crosshead die coating resin. The foamable vinyl chloride resin in a molten state is supplied into the flow channel by the second extruder, and the foamable vinyl chloride resin is extruded from the coating resin flow channel in the sizing die for selka process provided subsequently to the Kushead die. By foaming so as to swell in the inner diameter direction and sequentially forming a coating layer on the outer peripheral surface of the pipe body that has passed through the pipe body passage, it is possible to obtain a pipe body with good dimensional accuracy, and The interfacial adhesive strength between the main body and the coating layer is adjusted so that it can be peeled off manually, and further, by the coating layer,
The transferred high-temperature fluid is kept warm and has heat insulation to the outside.

Further, by adopting the sizing die for celcaprocell, the coating layer is composed of an inner layer part made of foam and a substantially non-foamed surface layer part formed on the outer peripheral surface thereof, and both are integrally formed. Therefore, the inner layer portion is reinforced by the surface layer portion, so that the inner layer portion is prevented from being thermally deformed or peeled off due to the passage of time during the transfer of the high temperature fluid, and there is no water absorption from the surface.

Further, since a vinyl chloride resin is used as a molding material for the pipe body and the coating layer, it has all the quality characteristics possessed by this kind of resin. When a chlorinated vinyl chloride resin is used for both molding materials, a resin having even higher heat resistance can be obtained.

[0038]

Embodiments of the present invention will be described below. FIG. 1 is a sectional view showing an example of the composite pipe of the present invention. As shown in the figure, in the composite pipe 1 (P), a coating layer 12 made of vinyl chloride resin is provided on the outer peripheral surface of a pipe body 11 made of vinyl chloride resin,
The coating layer 12 includes a foamed inner layer portion 121 and a substantially non-foamed surface layer portion 122 integrally formed on the outer periphery thereof.

The pipe body 11 may be formed mainly of chlorinated vinyl chloride resin. Composite pipe 1
As the outer surface shape of (P), for example, FIG.
As shown in (g), the cross-sectional outer shape includes a triangle, a quadrangle, a pentagon, a hexagon, an octagon, a quarter circle, a semicircle, etc. (Because the configuration is similar to that shown in FIG. ,
However, the present invention is not limited to these.

FIG. 3 is a schematic plan view for explaining the steps of an example of the method for manufacturing the composite pipe of the present invention. In the figure,
First, the device used will be described. Reference numeral 31 is a first extruder, and a pipe body molding die 32 is attached to the tip thereof. Reference numeral 33 denotes a first cooling device including a water tank, and a sizing die (not shown) is attached to the inlet of the first cooling device. The tubular body 11 extruded from the pipe body forming die 32 is regulated by the sizing die in outer dimensions. It is cooled with water. In addition to this, the cooling device may be one that showers cooling water on the surface of the tubular body 11.

Reference numeral 34 is a drying device having an annular duct and capable of ejecting warm air. In addition to this, the drying device may be one in which a plurality of infrared lamps are arranged along the traveling direction of the tubular body 11 to form a drying / heating zone.

Reference numeral 35 is a second extruder installed so as to be substantially perpendicular to the traveling direction of the tubular body 11, and a crosshead die 36 is attached to the tip thereof. 37 is a sizing die for selka process in the form of a short cylinder, which is provided so as to be directly connected to the tip of the crosshead die 36, and the outlet side half part thereof is a second cooling device 38 which is composed of a water tank that is continuously arranged. It is inserted and installed at the entrance of.

As a sizing die for the selka process, a temperature-controlled cooling fluid is circulated in an annular cavity formed between the inner and outer cylindrical walls of another short cylinder having a double cylinder structure. It may have a structure, and in this case, it is arranged at a distance from the second cooling device 38.

Next, an example of the method for manufacturing the composite pipe of the present invention using the above apparatus will be described. First, a vip body molding material and a coating layer molding material are prepared according to a predetermined composition. Next, the cylinder temperature of the first extruder 31 and the second extruder 35 is set to a predetermined temperature, and the first extruder 31
Is used to melt and knead the pipe body molding material, the tubular body 11 is extruded from the pipe body molding die 32, cooled by the first cooling device 33, and passed through the drying device 34 to extrude the pipe body S. Mold.

Subsequently, as shown in FIG. 4, the continuously molded pipe body S is introduced into the pipe body passage 36a of the crosshead die 36, and the coating material for the coating layer is melted by using the second extruder 35. -Knead and supply into the coating resin flow path 36b of the crosshead die 36.

In the sizing die 37 for the selka process, which is provided subsequent to the cus head die 36, the expandable vinyl chloride resin is extruded and foamed so as to swell in the inner diameter direction while being extruded from the coating resin channel 36b. A coating layer R is formed on the outer peripheral surface of the pipe body S that has passed through the pipe body passage 36a, and this is cooled by the second cooling device 38,
A composite pipe P is obtained by drying with a drying device (not shown), taking it with a take-up machine (not shown), and cutting it to an appropriate length.

The embodiment of the present invention will be specifically described with reference to examples. (Example 1) As a method of manufacturing a composite pipe, a method in which the extrusion coating molding method described with reference to FIGS. A 50 mmφ extrusion molding machine (Model BT-50, manufactured by Plastic Optical Laboratory Co., Ltd.) was used as the first extruder 31, and 3 was used as the second extruder 35.
Extruder with 0mmφ (Plastic Optical Laboratory Co.,
Model BT-30) was used.

Next, with respect to 100 parts by weight of a chlorinated vinyl chloride resin having a chlorine content of 66% by weight, 2 parts by weight of a tin-based stabilizer, 1 part by weight of an ester-based internal lubricant, and 2 parts by weight of a polyethylene edible wax-based external lubricant. , Acrylonitrile-butadiene-styrene copolymer (= ABS) impact modifier and 10 parts by weight of a pigment, and 1 part by weight of a pigment were mixed to prepare a pipe body molding material made of a chlorinated vinyl chloride resin composition. The cylinder temperature of the first extruder 31 was set to 150 to 190 ° C.

Next, using this pipe body molding material, the tubular body 11 is extruded from the first extruder 31, passed through the first cooling device 33 and continuously cooled, and then passed through the inside of the drying device 34. To dry and thus 25
mm, the pipe body S having an outer diameter of 32 mm was extruded.

On the other hand, vinyl chloride resin (average degree of polymerization = 6
00) 2 parts by weight of a tin-based stabilizer, 2 parts by weight of a thermal decomposition type inorganic foaming agent, 2 parts by weight of an ester-based internal lubricant, 2 parts by weight of a polyethylene wax-based external lubricant, and 1 part by weight of a pigment based on 100 parts by weight. A coating layer molding material made of the expandable vinyl chloride resin composition was prepared, and the cylinder temperature of the second extruder 35 was set to 140 to 180 ° C.

Then, the pipe body S which is continuously molded
Was passed through the pipe body passage 36a of the crosshead die 36. Further, the melt-kneaded material of the coating layer molding material is fed from the second extruder 35 to the coating resin flow path 16b of the crosshead die 36.
Supplied within.

In a selka process sizing die 37 provided subsequent to the crosshead die 36, a foamable vinyl chloride resin is extruded and foamed so as to swell in the inner diameter direction while being extruded from the coating resin flow path 36b. A coating layer R is formed on the outer peripheral surface of the pipe main body S that has passed through the main body pipe passage 36a, is cooled by a second cooling device 38, is dried by a drying device (not shown), and is taken by a take-up machine (not shown). Cut into appropriate lengths.

Thus, as shown in FIG. 1, on the outer peripheral surface of the pipe body 11, the inner layer 121 has a thickness of 7.4 mm and the surface layer 122 has a thickness of 0.6 mm.
Composite pipe 1 having an outer diameter of 48 mm and having a coating layer 12 formed thereon
(P) was obtained.

(Example 2) The cylinder temperature of the second extruder 35 was set to 160 to 190 ° C., and the chlorine content in the coating material of the coating layer was 66% by weight instead of the vinyl chloride resin. % Chlorinated vinyl chloride resin 100 parts by weight was used, and the thickness of the inner layer portion 121 was the same as in Example 1 except that 7 parts by weight of the ABS impact modifier used for the pipe molding material was also added. About 7.
An outer diameter of 48 m formed with a coating layer 12 having a total thickness of about 8 mm, which is 5 mm and the surface layer 122 has a thickness of about 0.5 mm.
A composite pipe 1 (P) as shown in FIG.

(Comparative Example 1) As a molding apparatus, JP-A-56
The apparatus described in JP-A-155727 (see FIG. 6) was used. That is, the same extruder as the first extruder 31 of the first embodiment is used as the extruder a, whereby the pipe body molding material is used, and the extruder b is used as the second extruder 3 of the first embodiment.
Using the same extrusion molding machine as in No. 5, melt and knead the coating layer molding material and extrude into the die c. Then, both molten resins are welded in the die c and extruded from the die lip to foam the coating layer molding material. Except for the above, in the same manner as in Example 1, a composite pipe having a pipe body thickness of 3.1 mm, the entire coating layer thickness of 8.4 mm, an inner diameter of 25 mm, and an outer diameter of 48 mm was obtained.

(Comparative Example 2) The same procedure as in Example 2 was repeated except that the same molding apparatus as Comparative Example 1 was used.
The thickness of the pipe body is 3.8 mm, and the thickness of the entire coating layer is 7.7.
mm, an inner diameter of 25 mm, and an outer diameter of 48 mm were obtained. Table 1 shows the compounding composition of each of Examples 1 and 2 and Comparative Examples 1 and 2.

[0057]

[Table 1]

With respect to the composite pipes obtained in Examples 1 and 2 and Comparative Examples 1 and 2, a heat distortion resistance test and a heat insulation evaluation 1 were carried out by the measuring method and the evaluating method described later. Table 2 shows the results. The same evaluation was performed on a commercially available heat-resistant pipe having the same inner diameter (“Eslon HT Pipe” manufactured by Sekisui Chemical Co., Ltd.). The results are also shown in Table 2.

[0059]

[Table 2]

(Example 3) As a method for producing a composite pipe, a method in which the extrusion coating method described with reference to FIGS. 3 and 4 and the Celka process method were connected was adopted. The cylinder temperature of the first extruder 31 is set to 150 to 190 ° C., and as a material for molding the pipe body, 2 parts by weight of a tin-based stabilizer and an ester are added to 100 parts by weight of a vinyl chloride resin (average degree of polymerization = 1000). In the same manner as in Example 1 except that a vinyl chloride resin composition prepared by mixing 1 part by weight of the internal lubricant, 2 parts by weight of the polyethylene wax external lubricant, and 1 part by weight of the pigment was used, Inner layer 1 on the outer peripheral surface
21 has a thickness of about 7.4 mm, and the surface layer 122 has a thickness of about 0.6.
A composite pipe 1 having an outer diameter of 48 mm and having a coating layer 12 having a total thickness of about 8 mm and having an outer diameter of 48 mm as shown in FIG.
(P) was obtained.

Example 4 The cylinder temperature of the first extruder 31 was set to 160 to 200 ° C., and in the pipe body molding material, 100 parts by weight of a chlorinated vinyl chloride resin having a chlorine content of 66 parts by weight was used instead of the vinyl chloride resin. Same as Example 3 except that 10 parts by weight of methylmethacrylate-butadiene-styrene copolymer system (MBS) impact modifier was added, in the same manner as the composite pipe obtained in Example 3. A composite pipe 1 (P) having the dimensions of as shown in FIG. 1 was obtained.

Example 5 The cylinder temperature of the second extruder 35 was set to 160 to 190 ° C., and in the coating layer molding material, instead of the vinyl chloride resin, a chlorinated vinyl chloride resin having a chlorine content of 66% by weight was used. 100 parts by weight, AB
A composite pipe 1 (P) as shown in FIG. 1 having the same dimensions as the composite pipe obtained in Example 3 was obtained in the same manner as in Example 4 except that 7 parts by weight of the S impact modifier was added. It was

(Comparative Example 3) As a molding apparatus, JP-A-56
The apparatus described in JP-A-155727 (see FIG. 6) was used. That is, as the extruder a, the same extruder as the first extruder 31 is arranged, whereby the pipe body molding material used in Example 3 is used, and the extruder b is also the same extruder as the second extruder 35. Example except that the coating layer molding material was placed, and the coating molding material was melted and kneaded thereby and extruded into the die c, and extruded from the die lip where both molten resins were welded in the die c to foam the coating layer molding material. In the same manner as in 3, a composite pipe having a pipe body thickness of 3.1 mm, the entire coating layer thickness of 8.4 mm, an inner diameter of 25 mm, and an outer diameter of 48 mm was obtained.

(Comparative Example 4) The procedure of Example 5 was repeated, except that the same apparatus as in Comparative Example 3 was used as the molding apparatus.
The thickness of the pipe body is 3.8 mm, and the thickness of the entire coating layer is 7.7.
mm, an inner diameter of 25 mm, and an outer diameter of 48 mm were obtained. Table 3 shows the compounding compositions of Examples 3 to 5 and Comparative Examples 3 and 4.

[0065]

[Table 3]

The composite pipes obtained in Examples 3 to 5 and Comparative Examples 3 and 4 were measured and evaluated for interfacial adhesion strength, heat distortion resistance and dimensional accuracy by the measuring method and evaluation method described later. The results are shown in Table 4.

[0067]

[Table 4]

(Example 6) The cylinder temperature of the first extruder 31 was set to 160 to 190 ° C, and 10 parts by weight of the MBS impact modifier was added to the molding material for the pipe body. Cylinder temperature 160-190
1 with the same dimensions as the composite pipe obtained in Example 3 except that 10 parts by weight of MBS impact modifier was added to the coating layer molding material.
A composite pipe 1 (P) as shown in was obtained.

(Comparative Example 5) The same procedure as in Example 6 was repeated except that the same apparatus as in Comparative Example 3 was used as the molding apparatus.
The thickness of the pipe body is 3.8 mm, and the thickness of the entire coating layer is 7.7.
mm, an inner diameter of 25 mm, and an outer diameter of 48 mm were obtained. Table 5 shows the compounding compositions of Example 6 and Comparative Example 5.

[0070]

[Table 5]

The composite pipes obtained in Example 6 and Comparative Example 5 were subjected to a heat deformability test and a heat insulating property evaluation 2 by the measuring method and the evaluating method described later. Table 6 shows the results. The same evaluation was performed on a commercially available heat-resistant pipe having the same inner diameter (“Eslon HT Pipe” manufactured by Sekisui Chemical Co., Ltd.). The results are also shown in Table 6.

[0072]

[Table 6]

The above measurement and evaluation methods are as follows. (1) Thermal deformability test Peeling off the coating layer from the pipe body and cutting out a standard length test piece, those with the surface layer portion have the surface layer portion, and those without the surface layer have the outer peripheral surface of the coating layer as the upper surface, The Vicat softening temperature was measured according to JIS K7206.

(2) Adiabatic Evaluation 1 Hot water at 80 ° C. was transferred to a sample pipe having a length of 20 m at a rate of 5 liters per minute, and the outlet temperature of hot water was measured.

(3) Thermal insulation evaluation 2 Thermal insulation evaluation Under the condition of the outside air temperature of 0 ° C., hot water of 40 ° C. was transferred at a rate of 10 liters per minute to a sample pipe having a length of 50 m, and the outlet temperature of the hot water temperature was measured. Was measured. Cooling property evaluation Under the condition of outside air temperature of 30 ° C., hot water of 4 ° C. was transferred to a pipe of 50 m at a rate of 10 liters / min, and the outlet temperature of the hot water temperature was measured.

(4) Interfacial adhesion strength Five pieces of each composite pipe as shown in FIG. 5 were prepared and left in a thermostatic chamber at 23 ° C. for 48 hours, and then, 23
The sample was pulled at a rate of 500 mm / min at 0 ° C., the tensile shear strength at the time of breaking of the interface was measured by an autograph, and the average value of the obtained five measured values was calculated.

(5) Dimensional accuracy The coating layer was peeled and removed from each composite pipe, and the outside diameter and inside diameter of the pipe body were measured.

[0078]

EFFECTS OF THE INVENTION Since the composite pipe of the present invention 1 is constructed as described above, the production of the coating layer is inexpensive, and the presence of the surface layer portion promotes the thermal deformation preventing property of the coating layer. The heat insulation and heat retention functions are maintained over time, and scratch resistance is also imparted. The vinyl chloride resin pipe has all the quality characteristics originally possessed.

Since the composite pipe of the second aspect of the present invention is constructed as described above, the interfacial adhesion strength between the pipe body and the coating layer can be peeled off manually without sacrificing the heat insulation / heat retaining function of the coating layer. It is possible to improve the connection work of the joint. Since the composite pipe of the third aspect of the present invention is configured as described above, the pipe body is excellent in thermal deformation resistance, and in turn, thermal deformation of the coating layer can be prevented.

Since the composite pipe manufacturing method of the fourth aspect of the present invention is configured as described above, the interfacial adhesive strength between the pipe body and the coating layer does not sacrifice the heat insulating / heat retaining function of the coating layer. Since it can be peeled off manually, it is possible to manufacture a composite pipe having excellent joint connection work. Further, by adopting the sizing die for the selka process, the coating layer has a structure having an inner layer made of foam and a substantially non-foamed surface layer portion formed on the outer periphery thereof, and both are integrated. , Excellent in heat deformation prevention and non-absorption, and excellent in heat insulation and heat retention function can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a composite pipe of the present invention.

FIG. 2 is a cross-sectional view for explaining the cross-sectional outer shape of the composite pipe of the present invention, where (a) is a triangle, (b) is a quadrangle, (c) is a pentagon, (d) is a hexagon, and (e) is an octagon. Square, (f) is 1
/ 4 circle, (g) is a cross-sectional view showing a semicircle, respectively.

FIG. 3 is a partial cross-sectional view illustrating steps of an example of a method for manufacturing a composite pipe of the present invention.

FIG. 4 is a cross-sectional view showing an enlarged main part of FIG.

FIG. 5 is an explanatory view of a test piece for measuring the tensile shear strength of the present invention, (a) is a front view thereof, and (b) is a plan view thereof.

FIG. 6 is a cross-sectional view illustrating an example of a conventional method for manufacturing a composite pipe.

[Explanation of symbols]

 1, P Composite pipe S Pipe body 11 Pipe body 12, R Coating layer 31 First extruder 32 Pipe body forming die 33 First cooling device 34 Drying device 35 Second extruder 36 Crosshead die 37 Celca process sizing die 38 2nd cooling device 121 Inner layer part 122 Surface layer part

Claims (4)

[Claims] 1. A composite pipe in which a coating layer made of a vinyl chloride resin foam is provided on an outer peripheral surface of a pipe body made of a vinyl chloride resin, wherein the coating layer has a foamed inner layer portion and its inner layer portion. A composite pipe comprising a substantially non-foamed surface layer portion formed on the outer circumference, and an inner layer portion and a surface layer portion being integrally formed. 2. A composite pipe in which a coating layer made of a vinyl chloride resin foam is provided on an outer peripheral surface of a pipe body made of a vinyl chloride resin, the coating layer comprising a foamed inner layer portion and a foamed inner layer portion thereof. It is composed of a substantially non-foamed surface layer portion formed on the outer periphery, and an inner layer portion and a surface layer portion are integrally formed, and the tensile shear strength between the pipe body and the coating layer is 0.0.
A composite pipe characterized in that it is from 01 to 0.3 kg / cm ² . 3. The composite pipe according to claim 1, wherein the pipe body is made of chlorinated vinyl chloride resin. 4. A molten vinyl chloride resin is extruded by a first extruder and then cured to continuously form a pipe body, and the obtained pipe body is sequentially introduced into a pipe body passage of a crosshead die, The expandable vinyl chloride resin in a molten state is supplied by the second extruder into the coating resin flow path of the crosshead die, and in the sizing die for selka process which is provided subsequently to the crosshead die,
Extruding expandable vinyl chloride resin from the coating resin channel,
A method for producing a composite pipe, which comprises foaming so as to bulge in an inner diameter direction and sequentially forming a coating layer on the outer peripheral surface of the pipe body that has passed through the pipe body passage.