JP3209830B2 - Manufacturing method of composite pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a composite pipe in which the inner surface of a metal pipe is lined with a resin layer, and more particularly, to a method for providing a foamed resin layer in an intermediate layer, for example, for use in building drainage. The present invention relates to a method for manufacturing a suitable composite pipe.

[0002]

2. Description of the Related Art Among composite tubes in which the inner surface of a metal tube is lined with a resin layer, an inner solid resin layer (non-foamed resin layer)
Composite tube in which a foamable resin layer such as urethane is interposed as an intermediate layer between the metal tube and the outer metal tube (Japanese Utility Model Publication No. 55-35147).
For example, Japanese Patent Application Laid-Open No. H11-157686 has an advantage that when used as a drain pipe, the drainage sound is reduced by the sound absorbing effect of the foamed resin layer.

[0003] As a method for manufacturing a composite pipe having such a foamed resin layer as an intermediate layer, conventionally, a preformed solid resin pipe is inserted into a metal pipe, and a foamed resin such as urethane is placed between the two pipes. A method of bonding a resin solution to the inner surface of a metal tube while foaming and curing the solution by heating from the outside of the metal tube by interposing a resin solution, or a solid resin layer on the inner surface side using a two-layer extrusion mold,
By simultaneously extruding two layers of resin so that the foamable resin layer is located on the outer surface side, the foamable resin layer on the outer surface side is foamed, and the two-layer resin tube is inserted into the metal tube via an adhesive or the like. In this case, a method of expanding the diameter of the resin tube side or reducing the diameter of the metal tube to bond the two tubes together is mainly employed.

[0004]

By the way, in the above-mentioned conventional production methods, any of the foaming resin layers is caused by the flow of the undiluted solution of the foaming resin, or the occurrence of unevenness during extrusion to foaming at a high temperature. There is a problem that unevenness or uneven thickness occurs, or voids and the like occur between the foamed resin layer and each of the layers inside and outside thereof.

[0005] When the foamed resin layer is deviated or uneven in thickness, for example, when two composite pipes are connected by a joint, a step occurs in the pipe, and when the pipe is used as a drain pipe, This leads to the problem that solids and the like in the drainage adhere to this step. Also, if there is a gap between the foamable resin layer and any of the inner and outer tubes, water or the like enters the foamable resin layer through the tube end and corrodes the metal tube, It also causes the metal tube and the resin layer to peel off.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to obtain a stable and high-quality composite pipe in which the foaming resin layer is less likely to be deviated, uneven in thickness, or a gap between layers. It aims to provide a manufacturing method that can be used.

[0007]

In order to achieve the above object, a method for manufacturing a composite pipe according to the present invention uses a two-layer resin extrusion mold and a hard vinyl chloride resin on the inner surface side. <br/> lid resin layer, hard sodium bicarbonate or azo
With extruding the two layers of resin so that the foamed resin layer using a nil resin compound is located at the same time, molding the resin two-layer tube with reduced foaming by cooling the foamable resin of the outer surface side immediately after extruded that When the two-layer resin tube is inserted into the metal tube and integrated therewith, the foamable resin layer is foamed by heating and is brought into close contact with the inner surface of the metal tube.

[0008]

By rapidly cooling the foamable resin extruded from the two-layer resin extrusion mold, a two-layer resin tube having a foamable resin layer cured in a non-foamed state on the outer peripheral side is obtained. This 2
When the layer resin tube is inserted into the metal tube and then heated by post-heating to form a foam and adhere to the inner surface of the metal tube, there is no deviation or gap between the metal tube and the solid resin layer, and stable A composite pipe having a foamed resin layer having a uniform thickness in the intermediate layer can be obtained.

[0009]

FIG. 1 is a sectional view showing an apparatus used for manufacturing a two-layer resin tube 1 in the steps of an embodiment of the present invention.

The two-layer resin extrusion mold 10 has two resin inlets 11 and 12, each of which is connected to a main extruder and a sub-extruder (neither is shown). The resin inlets 11 and 12 are connected to the resin flow paths 13 and 1 respectively.
The resin flow paths 13 and 14 are joined before the cylindrical resin discharge port 15, and the resin from one resin inlet 11 is on the inner surface side and the resin is from the other resin inlet 12. Can be discharged from the cylindrical resin two-layer pipe 1 in which the resin is located on the outer surface side. Note that, in this figure, the two-layer resin extrusion die 10 only shows a portion related to resin circulation for the sake of explanation, and other detailed structures are omitted.

[0011] A refrigerant ejection portion 16 for ejecting air or other appropriate refrigerant C is disposed adjacent to the resin ejection port 15 of the two-layer resin extrusion die 10. The outer peripheral surface of the resin two-layer tube 1 extruded from the tube 15 can be uniformly cooled.

In such a manufacturing apparatus, the solid resin is fed from the main extruder through the resin inlet 11 to the two-layer resin extrusion die 10 and the resin inlet 12 from the sub-extruder.
The foamable resin is extruded in a molten state through the respective steps. Thereby, the foamable resin layer 1 is formed on the outer surface side from the resin discharge port 15.
a, The resin two-layer tube 1 having the solid resin layer 1b on the inner surface side is extruded, and the foamed resin layer 1a on the outer surface side of the resin two-layer tube 1 is supplied with air from the refrigerant ejection part 16 or other suitable refrigerant. It is quenched by C. As a result, foaming of the foamable resin layer 1a is prevented, and the resin two-layer tube 1 having the unfoamed foamed resin layer 1a outside the solid resin layer 1b is obtained.

The resin two-layer tube 1 obtained as described above
Is then inserted into the metal tube 2 as shown in the radial section in FIG. At this time, it is desirable to apply an adhesive to at least one of the outer peripheral surface of the resin two-layer tube 1 and the inner peripheral surface of the metal tube 2.

In this state, heating is performed from the outside of the metal tube 2 to foam the foamable resin layer 1a, and at the same time, the adhesive is melted to activate the adhesive. After the inner peripheral surfaces of the tubes 2 are adhered to each other, the tubes are cooled and solidified. As a result, as shown in the radial sectional view of FIG. 3, a composite pipe having the solid resin layer 1b as the inner layer, the foamable resin layer 1a in the foamed state as the intermediate layer, and the metal pipe 2 as the outer layer is obtained. Note that an adhesive layer is actually interposed between the foamable resin layer 1a and the metal tube 2, but illustration of the adhesive layer is omitted in FIG.

According to such a manufacturing method, the foamable resin layer 1a is interposed between the solid resin layer 1b and the metal tube 2 in a state of being cured without being foamed, and is foamed by post-heating in that state. , Solid resin layer 1b and metal tube 2
In the space regulated between the two, no unevenness or uneven foaming occurs, and uneven thickness of the foamable resin layer 1a and generation of voids between layers hardly occur.

Here, the resin double-layer pipe 1 is inserted into the metal pipe 2 in a state where the adhesive is applied to any of them, and the foamable resin layer 1 is formed.
Before foaming a by heating from the outside, a step of reducing the diameter of the metal tube 2 may be inserted.

Next, an example in which a composite pipe is actually manufactured by using the manufacturing method of the present invention as described above will be described. <First Example> A baking soda (or diazo) hard vinyl chloride resin compound was used as the foamable resin for the intermediate layer, and the resin inflow port 12 of the two-layer resin extrusion mold 10 shown in FIG.
Led to.

Hard vinyl chloride as the inner layer solid resin
The resin was guided from the main extruder to the resin inlet 11 of the two-layer resin extrusion die 10. Then, these resins are melted and merged in the two-layer resin extrusion mold 10 and immediately cooled by air immediately after coming out of the resin discharge port 15 to form the resin two-layer tube 1 in which the foamable resin is cured in an unfoamed state. Obtained.

A steel pipe is used as the metal pipe 2. A thermoplastic hot-melt adhesive is applied to the outer surface of the resin two-layer pipe 1 obtained above, then inserted into the metal pipe 2 and heated from outside to form a foam. The resin layer 1a was foamed, and the adhesive was melted to perform adhesive activity. Thereafter, the entire tube was cooled.

<Second Example> The process is the same as that of the first example until the production of the resin two-layer tube 1 having the foamable resin layer 1a cured in an unfoamed state on the outer surface and the application of the adhesive to the outer surface. ,
With this inserted into the metal tube 2, the diameter of the metal tube 2 is reduced,
Thereafter, the foamable resin layer 1a was foamed by external heating, and finally the entire pipe was cooled in the same manner.

In any of the first and second examples described above, no uneven thickness of the foamable resin layer 1a and no void between the layers were found.

[0022]

As described above, according to the present invention,
When manufacturing a composite tube having a foamable resin layer as an intermediate layer between a solid resin layer and a metal tube, first, a hard vinyl chloride resin is used on the inner surface side with a two-layer resin extrusion mold.
With a solid resin layer and a baking soda or azo-based hard
Two layers of resin are simultaneously extruded using a vinyl chloride resin compound so that the foamable resin layer is positioned, and immediately after the extrusion, the foamable resin on the outer surface side is cooled to suppress the foaming of the resin two-layer pipe. In molding and then inserting the two-layer resin tube into the metal tube and integrating the same, the foamable resin layer is foamed by heating and adheres tightly to the inner surface of the metal tube. No voids, etc.
It has become possible to manufacture composite pipes with low drainage sound and low propagation sound stably and with high quality.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an apparatus used for manufacturing a resin two-layer tube 1 in a process of an embodiment of the present invention

FIG. 2 is a sectional view showing a part of the process of the embodiment of the present invention.

FIG. 3 is a cross-sectional view of a composite pipe obtained by the steps of the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 resin two-layer tube 1a foamable resin layer 1b solid resin layer 2 metal tube 10 two-layer resin extrusion die 15 resin discharge port 16 refrigerant ejection part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI B29L 9:00 B29L 9:00 23:00 23:00

Claims (1)

(57) [Claims] 1. A solid resin layer using a hard vinyl chloride resin on the inner surface side and a sodium bicarbonate or azo-based hard vinyl chloride resin compound on the outer surface side using a two-layer resin extrusion mold.
With extruding the two layers of resin so that the foamed resin layer is positioned simultaneously using de, by molding a resin two-layer tube with reduced foaming by cooling the foamable resin of the outer surface side immediately after extruded thereof, A method of manufacturing a composite pipe in which the foamable resin layer is foamed by heating and closely adhered to the inner surface of the metal pipe when the resin two-layer pipe is inserted into the metal pipe and integrated.