JP2002181279A - Thermally shrinkable tube and covering method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermally shrinkable tube facilitating the release of a release layer even with a small clearance with a matter to be covered and a covering method using it. SOLUTION: This thermally shrinkable tube comprises a cylindrical outer layer 1 consisting of a thermally shrinkable material, an adhesive inner layer 2 formed on at least a part of the inner surface thereof, and the release layer 3 adhered to the substantially whole inner surface of the inner layer 2. At least a part of one end of the release layer 3 is extended, and turned up so that its tip 3a is located on the outside of the other end of the outer layer 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-shrinkable tube having a tubular outer layer made of a heat-shrinkable material, an inner layer having adhesiveness, and a release layer attached to the inner surface thereof, and a coating method using the same. For example, it is useful for anticorrosion coating of welded portions of coated steel pipes used for pipelines for transporting city gas, tap water, oil, steam for district heating, and the like.

[0002]

2. Description of the Related Art Generally, steel pipes are used as pipelines for transporting city gas, tap water, petroleum, steam, and the like. However, steel pipes are easily corroded in the presence of water or oxygen.
Therefore, it is common practice to form a coating layer that covers the surface of the steel pipe with asphalt, coal tar enamel or polyethylene (PE), epoxy, urethane, or the like. Since such a coating layer is formed in a factory, it is also called a factory coating layer.

[0003] When pipe ends are to be welded to each other by butt-welding the pipe ends of a coated steel pipe having a coating layer formed on a surface thereof, the coating layer near the pipe ends is removed in advance, and then the pipe ends are connected to each other on site. After welding, anticorrosion coating of the welded portion is performed with a heat-shrinkable tube inserted in advance. The heat-shrinkable tube generally has an outer layer made of a heat-shrinkable material on the outer periphery, an inner layer having an adhesive property on the inner surface, and a release paper or the like on the innermost periphery. The heat-shrinkable tube is inserted into the coated steel pipe in advance, moved to the welded portion after welding, then the release paper is removed, and then heated to shrink the heat-shrinkable tube and adhered to the welded portion to provide anticorrosion coating. You.

[0004]

However, the diameter of the heat-shrinkable tube is reduced in order to reduce the working time and the material cost, and the clearance between the coated steel pipe to be constructed and the heat-shrinkable tube is reduced. On the other hand. Conventionally, the release paper was divided into several parts and attached to the inner layer material, and the release paper was removed at the time of repair. However, due to the decrease in clearance, it took time to remove the release paper at the time of construction. Further, when the release paper is torn, there arises a problem that it is difficult to remove the release paper.

Conventionally, in order to heat the heat-shrinkable tube, heat shrinkage of the heat-shrinkable tube has been performed after the preheating step of the coated steel pipe. , And a reduction in the time required for the peeling process. The requirement for the reduction in the diameter of the heat-shrinkable tube and the ease of peeling of the peeling layer is not limited to the coating of the welded portion as described above, but is a common problem in a coating method for a tubular article or a columnar article.

Accordingly, an object of the present invention is to provide a heat-shrinkable tube capable of easily peeling off a peeling layer even when a clearance with an object to be coated is small, and a coating method using the same.

[0007]

The above object can be achieved by the present invention as described below.

That is, the heat-shrinkable tube of the present invention has a cylindrical outer layer made of a heat-shrinkable material, an adhesive inner layer formed on at least a part of its inner surface, and a substantially entire inner surface of the inner layer. In a heat-shrinkable tube having a release layer, at least a part of one end of the release layer is extended,
The tip is folded back so that it is located outside the other end of the outer layer.

In the above, it is preferable that the release layer is formed by dividing a cylindrical release paper or release film at one or more locations in the circumferential direction.

On the other hand, the coating method of the present invention comprises the steps of extrapolating any one of the above heat-shrinkable tubes to an object to be coated having an outer diameter 5 to 40 mm smaller than the inner diameter of the outer layer; A step of peeling off the release layer by using a folded end of the release layer located outside of the above, and a step of thermally shrinking the heat-shrinkable tube after peeling.

According to the heat-shrinkable tube of the present invention, one end of the release layer is extended and its tip is folded back to the other end, so that the tip is moved to the other end. The release layer can be easily peeled off to the other end. At that time, the tip is located outside the other end of the outer layer,
Because peeling can be performed outside the gap with the object to be coated,
Even when the clearance with the object to be coated is small, the release layer can be easily separated.

When the release layer is formed by dividing a cylindrical release paper or a release film at one or more locations in the circumferential direction, the release layer can be removed without cutting the release layer after the release. Since there is no need to peel off along the outer periphery of the object, the workability of the peeling is further improved.

On the other hand, according to the coating method of the present invention, since any one of the above-mentioned heat-shrinkable tubes is used, the inner diameter of the outer layer is 5 mm.
Even for coating objects having an outer diameter of ~ 40 mm smaller,
The release layer can be easily removed. Further, since the clearance with the object to be coated is small, the construction time when the heat-shrinkable tube is thermally shrunk can be shortened.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an axial sectional view showing an example of the heat-shrinkable tube of the present invention, and FIG. 2 is a perspective view of a main part showing only a release layer thereof.

As shown in FIG. 1, the heat-shrinkable tube of the present invention has a tubular outer layer 1 made of a heat-shrinkable material, an inner layer 2 having an adhesive property formed on at least a part of its inner surface, and an inner layer 2 having an adhesive property. And a release layer 3 attached to substantially the entire inner surface of the substrate 2. In the present embodiment, an example is shown in which the inner layer 2 is formed on the entire inner surface of the outer layer 1 and the release layer 3 adheres to the entire inner surface.

The release layer 3 has one end 3b extended,
The tip 3a is folded back so as to be located outside the other end 1a of the outer layer 1. That is, it has a double structure of the attachment portion 3c attached to the inner surface of the inner layer 2 and the folded portion 3d. When the one end 3b of the release layer 3 is extended, the folded portion 3d is formed separately from the attachment portion 3c, and the two are adhered to each other.
It may be extended by joining by fusion or the like.

The tip 3a of the folded portion 3d may be subjected to anti-slip processing, embossing, punching, or the like so as to easily apply a pulling force.

The release layer 3 in the present invention is preferably formed by dividing a cylindrical release paper or release film at one or more locations in the circumferential direction. The number of divisions is preferably from 1 to 4. In the present embodiment, as shown in FIG. 2, it is divided by one dividing part 4, and cutting lines 4a and 4b along the longitudinal direction are formed. The direction and shape of the cutting lines 4a and 4b may be any.

As the heat-shrinkable material constituting the outer layer 1, any material can be used as long as it can be coated by heat-shrinkage. For example, heat-shrinkable polyethylene, heat-shrinkable polypropylene, heat-shrinkable polyvinyl chloride, heat-shrinkable polyamide and the like can be mentioned, and crosslinked polyethylene having an electron beam crosslinked gel fraction of 30 to 60% can be preferably used.

The inner layer 2 may also have an adhesive property by various methods, such as a pressure-sensitive adhesive, a hot melt adhesive,
Any of a thermosetting adhesive and a mastic type adhesive can be used. The inner layer 2 does not need to be provided on the entire inner surface of the outer layer 1, and may be provided in a ring shape on the inner surface near only both ends of the outer layer 1.

For the release layer 3, a so-called separator whose surface is surface-treated with a release agent such as silicone can be used.
As the base material, films, papers or laminates thereof made of polymers such as polyester, polyethylene, polypropylene and polyvinyl chloride are used. The thickness of the release layer 3 is preferably from 50 to 500 μm, more preferably from 70 to 250 μm, in order to secure a certain degree of flexibility while maintaining strength at the time of release.

Further, the present invention is not limited to the above-described embodiment, and may be one in which a release layer 3 shown in FIGS. 3 (a) and 3 (b) is formed, for example. FIGS. 3A and 3B are perspective views of a main part showing only a release layer in the present invention.

FIG. 3A shows a folded portion 3d.
Is substantially triangular, and a portion corresponding to the apex is a tip 3a, whereby the tip 3a of the release layer 3 is pulled so that the release layer 3 can be more easily peeled off. When this release layer 3 is developed, it becomes substantially pentagonal as a whole.

FIG. 3 (b) shows a structure in which the separation layer 4 is provided at two places, and the peeling layer 3 can be more easily peeled off by pulling the tips 3a of the two separated peeling layers 3. It was made. Increasing the number of divisions has the advantage that the peeling force for each decreases.

In manufacturing the heat-shrinkable tube of the present invention,
The method of adhering the release layer 3 to the inner surface of the inner layer 2 in the above-described form is, for example, attaching a double-folded release paper or release film to the inner surface, or applying a release paper or release film in an unfolded state before being folded. After being attached to the inner surface, it may be folded back.

Next, a method of using the above-described heat-shrinkable tube will be described with reference to FIG. FIG.
This is an example of a case where the pipe ends of the coated steel pipes are butt-welded to each other, and then the anticorrosion coating of the welded parts is performed with a heat-shrinkable tube inserted in advance.

First, a heat-shrinkable tube is extrapolated to a steel pipe 10 to be coated.
Done from The steel pipe 10 is made of, for example, city gas, tap water,
It is used as a pipeline for transporting oil, steam, etc. In this case, a coating layer 1 is formed on the surface to prevent corrosion.
1 is often formed. Examples of the coating layer 11 include asphalt, coal tar enamel or polyethylene (PE), epoxy, urethane, and the like.

The heat-shrinkable tube of the present invention can be used for any object other than the object having an outer diameter extremely smaller than the inner diameter of the outer layer 1 of the heat-shrinkable tube. The object to be coated having an outer diameter of 5 to 40 mm smaller than the inner diameter of 1, and even the object to be coated having an outer diameter of 5 to 30 mm smaller can be used. Since the clearance with the object to be coated can be reduced in this way,
Coating by heat shrinkage can be performed in a shorter time.

When the pipe ends 10a of such coated steel pipes are butt-welded to each other to perform piping work, the coating layer 11 near the pipe ends 10b is removed in advance, and then the pipe ends 10a
Weld each other on site. The extrapolated heat shrink tube is moved to a position away from the welding position during welding,
Move to the weld after welding.

In this state, the folded end 3a of the release layer 3 located outside the extrapolated heat-shrinkable tube is used,
The release layer 3 is peeled off. The peeling may be performed by relatively moving the heat-shrinkable tube and the tip 3a. For example, the position of the heat-shrinkable tube may be fixed, and the tip 3a may be pulled in the direction of the arrow. At that time, a jig, a tool, or the like may be used.

Next, if necessary, the heat-shrinkable tube is moved to a predetermined position and then heat-shrinked. Due to this heat shrinkage, the heat shrinkable tube adheres to the region including the welded portion to form an anticorrosion coating.

As the method of heat shrinking, any method can be used as long as it can cover the heat shrinkable material by heat shrinking, and examples thereof include methods using various burners such as gas burners, electric heaters, heating gases and the like. .

The coating method of the present invention comprises the steps of extrapolating the heat-shrinkable tube of the present invention to an object to be coated having an outer diameter 5 to 40 mm smaller than the inner diameter of the outer layer; The method includes a step of peeling off the release layer by using the folded end of the release layer located, and a step of thermally shrinking the heat-shrinkable tube after peeling. Each of these steps is as described above.

The object to be coated is not limited to a coated steel pipe for the purpose of corrosion protection, but may be any of various metal pipes, resin pipes, metal pillars, and the like. Any method such as improvement of water resistance may be used.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments and the like specifically showing the configuration and effects of the present invention will be described below.

Example 1 As shown in FIG. 1, the outer layer 1 (t
= 1.5 mm) and a release paper 3 having one end folded on the inner surface thereof was attached to a heat-shrinkable tube (inner diameter 240 mm) composed of the inner layer 2 (t = 0.6 mm). As coated steel pipe, outer diameter 220 mm with polyethylene coating layer 11 formed on the outer peripheral surface
The PLP tube was used to perform corrosion protection using the heat-shrinkable tube. The release paper 3 was easily removed. The contraction of the heat-shrinkable tube was performed with a gas burner, and the construction time was 4 minutes.

To examine the anticorrosion performance, a peeling test was performed in the longitudinal direction on the polyethylene coating layer 11 of the PLP tube, and the adhesive strength of the heat-shrinkable tube was measured. It was 5 kg / cm or more as measured by 180 ° peel.

Comparative Example 1 As shown in FIG. 4, the outer layer 1 (t
= 1.5 mm) and a release paper 3 was attached to a heat-shrinkable tube (270 mm inner diameter) composed of the inner layer 2 (t = 0.6 mm). As a coated steel pipe, a polyethylene coating layer 1
Using the PLP tube 20 having a diameter of 220 mm on which the No. 1 was formed, anticorrosion work was performed using the heat-shrinkable tube. Shrinkage of the heat-shrinkable tube was performed with a gas burner, and the construction time was 6 minutes.

In order to examine the anticorrosion performance, a peel test was performed in the longitudinal direction on the polyethylene coating layer 11 of the PLP tube, and the adhesive strength of the heat-shrinkable tube was measured. It was 5 kg / cm or more as measured by 180 ° peel.

As shown by the results, the PLP
It can be said that using a heat-shrinkable tube with a small clearance for a steel pipe is an effective means for shortening the construction time.

[Brief description of the drawings]

FIG. 1 is an axial sectional view showing a use state of an example of a heat-shrinkable tube of the present invention.

FIG. 2 is a perspective view of a main part showing only a release layer in FIG. 1;

FIG. 3 is a perspective view of a main part of another release layer according to the present invention.

FIG. 4 is an axial sectional view showing an example of use of a conventional heat-shrinkable tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer layer 2 Inner layer 3 Release layer (release paper) 3a Tip 3d Folded part 4 Split part 10 Steel pipe 11 Coating layer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3H024 EA04 EE02 EF15 EF19 4F100 AK04 AR00A AR00B AR00C BA03 BA07 BA10A BA10C DB07C DG10C GB90 JA03A JL11B JL14 JL14C

Claims (3)

[Claims] 1. A heat shrink comprising a cylindrical outer layer made of a heat shrinkable material, an inner layer having adhesiveness formed on at least a part of an inner surface thereof, and a release layer adhered to substantially the entire inner surface of the inner layer. A heat-shrinkable tube, characterized in that at least a part of one end of the release layer is extended and the tip is folded so as to be located outside the other end of the outer layer. 2. The heat-shrinkable tube according to claim 1, wherein the release layer is formed by dividing a cylindrical release paper or release film at one or more locations in a circumferential direction. 3. A step of extrapolating the heat-shrinkable tube according to claim 1 or 2 to an object to be coated having an outer diameter 5 to 40 mm smaller than the inner diameter of the outer layer, and applying the heat-shrinkable tube outside the extrapolated heat-shrinkable tube. A coating method comprising: a step of peeling off the release layer using a folded end of the release layer located; and a step of thermally shrinking the heat-shrinkable tube after peeling.