JP2001324085A - Coated polyethylene pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coated polyethylene pipe that can be easily and accurately adjusted in dimension and cut at a random size in the field, and has a heat insulation structure for preventing flaws on the surface of the polyethylene pipe. SOLUTION: The outer surface of the coated polyethylene pipe is coated with a two-layer foaming body layer and has a metal layer on the outermost layer. The two-layer foaming body layer comprises a soft foaming body contacting with the polyethylene pipe and a hard foaming body applied to its outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated polyethylene pipe used for a heat-retaining water pipe or the like in which a foam is used as a heat insulating material, and more particularly to a coated polyethylene pipe having a characteristic heat insulating material structure.

[0002]

2. Description of the Related Art As a method for coating a polyethylene pipe with a heat insulating material, a method of coating a polyethylene pipe without a heat insulating material with a single-layer heat insulating material after pipe construction, or a method of coating a heat insulating polyethylene pipe previously coated with a single-layer heat insulating material. There is a method of using and piping. Further, if necessary, the outermost layer is a metal tube; a spiral tube in which a metal strip is spirally wound; and a synthetic resin sheet or tape is used to improve weather resistance and strength. . The latter method is preferably used because there is an advantage that the heat retention of the pipe is assured and the pipe construction work only needs to be performed once.

[0003] In general, a heat-insulating polyethylene pipe is manufactured by extrusion-injection-foaming a foam, so that the polyethylene pipe and the heat-insulating layer are difficult to slide easily. When connecting polyethylene pipes at the required site, for example, when connecting joints, etc., when constructing polyethylene pipes at the required site, make a fractional length heat-insulated polyethylene pipe in advance according to the site, or make it to the required length at the construction site It is used after being cut to random size.

[0004] When cutting to an irregular size at the site, an operation of peeling off the heat insulating material from the polyethylene pipe is performed. First, a metal layer of a predetermined length is peeled off with a sander or the like, and then the heat insulating material is removed with a knife or the like. Using, a cut is made in the circumferential direction of the pipe at a position corresponding to a predetermined stripping length from the pipe end,
Further, a cut is made parallel to the pipe axis, and the heat insulating material is peeled off from the pipe end.

[0005] At this time, if the cutting end of a knife or the like for making a cut hits the inner surface of the polyethylene pipe and causes unnecessary damage to the polyethylene pipe, or if a shallow cut is made in order to avoid the damage, the heat insulating material will cut off the chitin. It has been pointed out that it is difficult to adjust the exact dimensions due to breakage of the heat insulating material at the time of peeling because it is not performed. In other words, the advantages of the polyethylene tube, such as easy cutting and easy on-site dimensional adjustment, were hindered. Therefore, there has been a problem that skilled techniques are often required for such reliable piping construction of the heat-retained polyethylene pipe.

[0006] For this reason, a factory is required to prepare in advance a coated polyethylene pipe of a precise irregular size required for each site in the factory. It has been pointed out that the problem is likely to occur.

[0007]

DISCLOSURE OF THE INVENTION The present invention relates to a heat insulating material structure which can easily and accurately adjust dimensions and cuts at random dimensions on site, and does not easily damage the surface of a polyethylene pipe during dimensional processing. The purpose of the present invention is to provide a coated polyethylene tube having the following.

[0008]

According to the present invention, there is provided a coated polyethylene pipe having an expansion ratio of 10 to 35 times and a 25% compressive strength of 2 to 60 N / cm on the outer surface of the polyethylene pipe. ² of the foam is coated laminated, it said face 5% compression strength of the foam is 10 N / cm ² or more foam is coated laminated, coated polyethylene, wherein a metal layer is formed by coating the outermost surface Tube.

The material of the foam (hereinafter referred to as the first layer heat insulating material) in contact with the polyethylene pipe has a heat insulating effect and is easily non-adhered or peeled off from the polyethylene pipe in contact with the inner surface thereof and is torn by hand. As a so-called flexible foam, the material is not particularly limited. For example, a continuous foam or a closed foam such as a synthetic resin such as urethane resin, polyvinyl chloride, polyethylene, polypropylene, and polystyrene, or a synthetic resin obtained by modifying them. Body.

This flexible foam has an expansion ratio of 10 to 3 times.
A material having a 5 times and 25% compressive strength of 2 to 60 N / cm ² is used. When the expansion ratio and the 25% compressive strength are within these ranges, sliding between the polyethylene tube and the foam is relatively easy, and furthermore, the deformed foam hardly remains in the deformed foam, which is more preferable. Means that the expansion ratio is 1
Those having 5 to 30 times and a 25% compressive strength of ² to 40 N / cm ² are used.

The thickness is not particularly limited as long as it can be appropriately selected and determined according to the material of the flexible foam, the expansion ratio, and the diameter of the pipe to be applied. The first layer of heat insulating material should be thick enough so that the cutting edge of a knife or the like does not hit the polyethylene pipe in contact with the inner surface.Thus, the thicker is better. It is not preferable because it may be deformed. For example, as an example, usually, when a soft urethane foam having an expansion ratio of 15 times is used, the nominal diameter is 100 mm and the SDR11
In many cases, the thickness of the first layer heat insulating material is about 3 mm with respect to the polyethylene pipe.

If the first layer heat insulating material is not adhered to the polyethylene pipe, the polyethylene pipe can be slid within the first layer heat insulating material. When the polyethylene pipe is slid, the first layer heat insulating material is deformed by friction or the like.However, since the polyethylene foam is a soft foam and has a thickness capable of accepting the amount of deformation, the polyethylene pipe has its original shape. The shape is completely restored when returned to position. Therefore, even when the polyethylene pipe is repeatedly slid, no creep deformation remains, and repeated sliding is possible.

The foam in contact with the metal layer (hereinafter referred to as the second layer heat insulating material) may be the same as that used for ordinary heat insulating material-coated polyethylene pipes, that is, a so-called rigid foam. That is, as an example, urethane resin, polyvinyl chloride, polyethylene, polypropylene, a synthetic resin such as polystyrene or a foam thereof such as a modified synthetic resin, preferably a closed-cell foam as a foam form. .

The thickness of the second layer heat insulating material may be appropriately selected and determined according to the type and expansion ratio of the foam to be used, the diameter of the polyethylene pipe, and the like. For example, when a rigid urethane resin foam is used, Is the ratio d / e of the pipe outer diameter d to the pipe wall thickness e (hereinafter referred to as SDR (Standard Di
mension Ratio). In many cases, a polyethylene pipe having a thickness of 15 mm or more and a foaming ratio of 1.3 or more is applied to a polyethylene pipe having a diameter of 11 or more.

The outermost metal layer is provided for the purpose of preventing the heat insulating material from being damaged by hitting an object, and preventing the heat insulating material from being deteriorated by being exposed to the outside air. Accordingly, the material is not particularly limited as long as the above object can be achieved. For example, as an example, stainless steel, iron, iron subjected to a touch-resistant treatment, and the like;
Synthetic resins, fiber-reinforced composite resins, stretched reinforced resins, and the like can be used. From the viewpoint of securing long-term weather resistance and reducing damage caused by flying objects, it is most preferable to use metals. In addition, the shape may be a pipe or a spirally wound strip.

As an example of a method for obtaining a coated polyethylene pipe having a foamed structure according to the present invention, for example, in the case of a batch method, a core pipe divided into three in the axial direction is restored to fit the pipe shape, and After laminating a flexible foam sheet on the outer circumference and inserting it into a steel pipe, and making the pipe axis of the core pipe substantially coincide with the pipe axis of the steel pipe, the soft foam sheet and the steel pipe laminated on the outer circumference of the core pipe are There is a method of injecting a hard foamable resin into a gap between the inner surface and foaming, and after completion of foaming, removing the core tube divided into three and inserting a polyethylene tube to obtain a coated polyethylene tube. Needless to say, the core tube may be a coated polyethylene tube without being extracted after foaming as the polyethylene tube itself without dividing into three.

(Function) As described above, in the present invention, since the foam layer has a two-layer structure, and the foam (the second layer heat insulating material) in contact with the metal layer is a rigid foam, the usual coated polyethylene is used. It can perform the same function as a pipe. In addition, since the foam (first layer heat insulating material) in contact with the polyethylene pipe is a soft foam, it can be easily peeled off when peeled from the polyethylene pipe in contact with the inner surface, and can be torn by hand. Therefore, even if the cutting depth is small, cutting can be easily and accurately performed without making a deep cut to the surface of the polyethylene pipe with a knife or the like, and the surface of the polyethylene pipe is hardly damaged.

If the heat insulating material of the first layer is not adhered to the polyethylene pipe, the polyethylene pipe can be easily slid and evacuated from the cut portion, and even if it is returned to the original position, the heat insulating layer of the polyethylene pipe can be easily removed. Since the deformation does not remain, the polyethylene pipe is slid and moved appropriately at the time of cutting to cut, so that the surface of the polyethylene pipe is not damaged and cutting can be easily performed with accurate dimensions.

[0019]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a partially cutaway sectional view of a coated polyethylene pipe 1 of the present invention. First, a flexible foamed polyethylene sheet (thickness 3 mm, expansion ratio 15 times, 25% compressive strength 5.9) was formed on the outer peripheral surface of a polyethylene pipe having a nominal diameter of 100 mm.
N / cm ² ) without any gap, and the above-mentioned polyethylene tube wound with a soft foamed polyethylene sheet is wound with an inner diameter of 1
The tube axis of the polyethylene tube is made to coincide with the tube axis through a 25 mm steel tube, the gap between both ends of the polyethylene tube and the steel tube around which the soft foamed polyethylene sheet is wound is closed with a closing plate, and one of the tube ends is closed. A urethane resin injection nozzle was provided on the plate. Then, a urethane resin (manufactured by Toyo Tire & Rubber Co., Ltd.) and a foaming agent (manufactured by Toyo Tire & Rubber Co., Ltd.) were added from the above-mentioned nozzle to 1:
The mixture was poured into the gap between the polyethylene tube and the steel tube while mixing the mixture into 1, and then allowed to stand at room temperature for 25 minutes to be cured to form a hard foam layer having 5% compressive strength of 13 N / cm ² , thereby obtaining a coated polyethylene tube.

When the inner layer polyethylene tube of the obtained coated polyethylene tube is pulled out by hand while supporting the outer layer foam, the first layer foam can be pulled out smoothly even after returning to the original position. Was not deformed.

The polyethylene tube is moved so as to protrude from the heat insulating material and cut into a predetermined length, and then the polyethylene tube is inserted into the heat insulating material, and its tip is pushed further inward from the cutting position of the heat insulating material. The first and second heat insulating layers were cut to a predetermined length and then returned to their original positions. After the completion of the cutting operation, the surface of the polyethylene tube was free of scratches and had good dimensional accuracy.

[0023] The coated polyethylene pipe was cut in a predetermined position, and only the second layer heat insulating material was cut in a circular shape with a knife at a position corresponding to the length connected to the joint from the cut end face. From the cut, a cut was made with a knife only in the first-layer heat insulating material parallel to the pipe axis toward the pipe end. Where the heat insulation is peeled off by hand, the second layer insulation can be peeled off smoothly,
The first layer of insulation was easily torn by hand. After the operation, there was no scratch on the polyethylene pipe surface and the dimensional accuracy was good.

[0024]

As described above, since the heat insulating material has a two-layer structure and the heat insulating material on the side in contact with the polyethylene pipe is a coated polyethylene pipe, the polyethylene pipe can be easily slid during the cutting operation. In addition, the heat insulating material is not deformed due to sliding, and the surface of the polyethylene pipe is not damaged, and cutting can be easily performed with accurate dimensions.

Further, since the soft foam can be easily torn off by hand, it is possible to make the cut of the knife shallow even when making a cut with a knife and peeling off the heat insulating layer. Cutting can be easily performed with accurate dimensions without being attached.

[Brief description of the drawings]

FIG. 1 is a partially broken sectional view of a coated polyethylene pipe of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Coated polyethylene pipe 2 Polyethylene pipe 3 First layer heat insulating material (soft foam) 4 Second layer heat insulating material (hard foam) 5 Outer layer material

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F16L 9/14 F16L 9/14 F-term (Reference) 3H036 AA01 AB25 AC06 AD09 3H111 AA01 BA01 BA15 BA34 CB05 CB30 DA15 DB03 4F100 AB01D AK04 AK04A AK07 AK12 AK15 AK51 BA04 BA10A BA10D CA01 DA11 DJ01B DJ01C GB90 JA13B JJ02 JK05B JK05C YY00B

Claims (1)

[Claims] 1. An expansion ratio of 1 on the outer surface of a polyethylene pipe.
0 to 35 times, and 25% compressive strength is 2 to 60 N / cm
² foam is coated and laminated, and a foam having a 5% compressive strength of 10 N / cm ² or more is coated and laminated on the outer surface of the foam,
A coated polyethylene pipe having an outermost surface coated with a metal layer.