JP2000033668A - Composite pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently utilize waste and to prevent the generation of uneveness by providing a tubular intermediate layer comprising waste based on a resin the same as the resin forming an inner layer comprising a thermoplastic resin pipe between an outer layer comprising a steel pipe and the inner layer comprising a thermoplastic resin. SOLUTION: A vinyl chloride resin is supplied to a first extruder and waste based on a vinyl chloride resin type resin is supplied to a second extruder. An inner layer 3 is extruded from the inner layer molding die of the first extruder to be cooled. Subsequently, the extrudate is introduced into an electric heater and the outer surface of the inner layer 3 is brought to a molten state to introduce the vinyl chloride resin and the waste into a crosshead die. The resin containing the waste is introduced into the crosshead die from the second extruder and the outer peripheral of the inner layer 3 is coated with the intermediate layer 2 to be cooled. Further, a primer and an adhesive are applied to the outer peripheral surface of the intermediate layer 3 and the intermediate layer and the inner layer 3 are inserted into a steel pipe 1 and thermally expanded to be bonded. By this constitution, the waste is efficiently utilized and the generation of unevenness can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite pipe, and more particularly, to a composite pipe obtained by recycling a resin which has been conventionally used as a waste.

[0002]

2. Description of the Related Art Conventionally, steel pipes lined with hard vinyl chloride resin have been used for drainage of buildings. In order to manufacture a steel pipe lined with such a hard vinyl chloride resin, a hard vinyl chloride resin pipe having a predetermined size (hereinafter, referred to as a “hard pipe”) is required.
Is manufactured simply by inserting it into a steel pipe.

[0003] These resin tubes are obtained by introducing a resin extruded in a state where a hard vinyl chloride resin is melted from an extruder into a mold, forming and cooling. At this time, it is required that the inner and outer surfaces of the resin tube have no irregularities, cracks, flatness, etc .; no foreign matter such as carbide; and excellent mechanical strength such as tensile strength and impact resistance.

With respect to these required qualities, if the molding conditions of the resin tube are stable, a product which satisfies the required qualities can be obtained. Defective products such as unevenness and curvature generated when there is an abnormality due to some disturbance are treated as waste. Also, pipes (including composite pipes) already piped as building materials are discarded when they are replaced with new ones due to aging.

[0005] These wastes not only lower production efficiency, but also require a huge amount of land and incineration equipment for disposal, which is a social problem. Therefore, it has been considered to reuse these wastes. However, molded products obtained by recycling waste often do not satisfy the required quality (see Japanese Patent Application Laid-Open No. 8-156612).
No. 7, Japanese Patent Publication No. 7).

Therefore, it is also practiced to pulverize the waste and mix it with a new raw material to obtain a molded product. However, when the resin tube is manufactured from such materials having different heat histories, the outer surface of the tube can be uniformly formed by forming, but the inner surface has fine irregularities (observed as "unevenness" visually). For example, in the case of a hard vinyl chloride resin, the ratio of waste to the entire raw material was limited to 40% by weight.

An object of the present invention is to solve the above-mentioned problems and to provide a composite pipe which can efficiently utilize waste and does not cause unevenness.

According to the present invention, there is provided a composite pipe comprising, between an outer layer made of a steel pipe and an inner layer made of a thermoplastic resin pipe, a waste mainly composed of the same resin as the resin forming the inner layer. And a tubular intermediate layer made of

[0007] The steel pipe used in the present invention is not particularly limited, and those usually used as steel pipes are used.

The thermoplastic resin used for the inner layer in the present invention is not particularly limited, and examples thereof include olefin resins such as polyethylene and polypropylene; vinyl chloride resins; fluororesins; and polyphenylene sulfide resins. Particularly, it is most effective when a vinyl chloride resin is used, which is difficult to dispose despite its high versatility. As the vinyl chloride resin, other than a homopolymer of a vinyl chloride monomer, for example, chlorinated vinyl chloride resin,
A copolymer of a vinyl chloride monomer and a polymerizable monomer other than the vinyl chloride monomer, a graft copolymer obtained by grafting a vinyl chloride monomer onto a polymer other than a vinyl chloride resin, and the like are used. You.

The thermoplastic resin used for the inner layer includes:
Waste may be added in an amount not exceeding 50% by weight of all components. If the amount of waste exceeds 50% by weight, irregularities are likely to be generated on the inner surface of the inner layer.

In the present invention, the waste used for the intermediate layer is a resin of the same type as the thermoplastic resin used for the inner layer, and is generated at the time of molding start-up, color change, end, and the like. A parison, or a defective product such as a flat product that occurs when something is wrong due to some disturbance. A tube that has already been installed as a building material and then replaced with a new one. Layer as a main component).

The intermediate layer may be formed entirely of waste, or a new thermoplastic resin may be added, if necessary, to the resin component used in the inner layer in a range not more than the resin component used for the inner layer. Is also good.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram illustrating steps of an example of a method for manufacturing a composite pipe according to the present invention. Reference numeral 10 denotes a first extruder, to which an inner layer forming die 11 is attached at the tip. Reference numeral 12 denotes a first cooling device including a water tank, and a sizing die (not shown) is attached to an inlet of the first cooling device. The inner layer 3 extruded from the inner layer forming die 11 is
It is water-cooled under the external size regulation by the sizing die.
The cooling device may be a device that showers cooling water on the surface of the inner layer 3.

Reference numeral 13 denotes an electric heating device (cast heater), which has a passage hole through which the inner layer 3 passes. The electric heating device 13 has a contact portion with the inner layer 3,
It also has a centering contact before being introduced into the inner layer passage of the crosshead die 15 of the extruder.

Reference numeral 14 denotes a second extruder installed so as to be substantially perpendicular to the traveling direction of the inner layer 3, and a crosshead die 15 is attached to the tip of the second extruder. The tubular layer 2 mainly composed of the waste extruded from the second extruder 14
Then, the inner layer 3 is fused and the surface of the inner layer 3 is covered with the intermediate layer 2. Subsequently, it is inserted / attached to the inlet of the second cooling device 17 composed of a water tank and is cooled.

In the method for producing a composite pipe according to the present invention, a primer and an adhesive are applied to the outer peripheral surface of an inner layer 3 (hereinafter referred to as a "laminated pipe") coated with an intermediate layer 2 obtained as described above. , Into the steel pipe 1. Next, the steel pipe having the laminated pipe inserted therein is heated by heating in a heating furnace or the like. Since the coefficient of thermal expansion of the laminated pipe is larger than the coefficient of thermal expansion of the steel pipe, the laminated pipe adheres tightly to the steel pipe 1 and is bonded via the adhesive.

[0016]

The present invention will be described in further detail with reference to examples. (Examples 1 and 2) As the first extruder 10, an extruder having a diameter of 50 mm (manufactured by Nagaoka Seisakusho Co., Ltd., model "SLM # 50"),
Using a 50 mmφ extruder (Model “UF50”, manufactured by Plastics Engineering Laboratory Co., Ltd.) as the second extruder 14, Table 1
A predetermined amount of vinyl chloride resin (average degree of polymerization 100
No. 0) was supplied to the first extruder 10, and a waste mainly containing a vinyl chloride resin (containing 85% by weight of the vinyl chloride resin) was supplied to the second extruder 14 from each hopper.

The first extruder 10 (barrel set temperature 185)
℃), the inner layer forming die 11 (set temperature 190 ℃)
Thus, the inner layer 3 having an inner diameter of 100 mmφ and an outer diameter of 104 mmφ was extruded, passed through the first cooling device 12 and continuously cooled.

Then, the inner layer 3 was introduced into an electric heating device 13 set at a heating temperature of 150 ° C., and the outer surface of the inner layer 3 was brought into a molten state and introduced into the crosshead die 15.

On the other hand, a resin containing waste is introduced from the second extruder 14 (barrel setting temperature 185 ° C.) to the crosshead die 15, and has an outer diameter of 106 mmφ and a thickness of 1.0 m.
m of the intermediate layer 2 covered the outer periphery of the inner layer 3.

Then, as shown in FIG. 1, an insertion / insertion is made at the entrance of the second cooling device 17 consisting of a water tank which is subsequently arranged.
After being attached and cooled, a laminated tube in which the intermediate layer 2 covered the outer periphery of the inner layer 3 was obtained. A part of the obtained laminated tube was cut, and unevenness (unevenness) on the inner surface and outer surface was visually observed. As a result, unevenness (unevenness) was not generated.

Further, a primer and an adhesive were applied to the outer peripheral surface of the obtained laminated pipe, and the steel pipe 1 (outer diameter: 114 mmφ,
(2.8 mm thick, manufactured by Nippon Steel Corporation), and heated and expanded for bonding to obtain a composite tube shown in FIG. When the inner surface of the obtained composite tube was visually observed, unevenness (unevenness) was observed.
Had not occurred.

Comparative Example 1 Using the first extruder 10,
Inner layer 3 (outer diameter 106 mmφ, thickness 3 m
m) was partially cut in the same manner as in Example 1 except that a tubular body consisting only of m) was obtained, and unevenness (concavities and convexities) on the inner surface and the outer surface were visually observed. Using this tubular body, a composite pipe was obtained by inserting and bonding the steel pipe 1 in the same manner as in Example 1. When the inner surface of the obtained composite pipe was visually observed, unevenness (unevenness) was found on the inner surface. Had occurred.

The above results are summarized in Table 1.

[0024]

[Table 1]

[0025]

The composite pipe of the present invention has a tubular shape made of a waste mainly composed of the same resin as the resin forming the inner layer between an outer layer made of a steel pipe and an inner layer made of a thermoplastic resin pipe. Since the intermediate layer is provided, waste can be efficiently used, and no irregularities are generated.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating steps of an example of a method for manufacturing a composite pipe according to the present invention. It is explanatory drawing which shows an example of the manufacturing method manhole joint of such a laminated pipe.

FIG. 2 is a cross-sectional view showing an example of the composite pipe of the present invention.

[Explanation of symbols]

 1 outer layer 2 middle layer 3 inner layer

Claims (1)

[Claims] 1. A tubular intermediate layer made of a waste mainly composed of the same resin as the resin forming the inner layer is provided between an outer layer made of a steel pipe and an inner layer made of a thermoplastic resin pipe. A composite pipe characterized by the above-mentioned.