JP2002327860A - Marker sheet for buried polyethylene gas pipe and method of making the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a marker sheet for a buried polyethylene gas pipe which can effectively utilizes waste materials of the polyethylene gas pipe. SOLUTION: A flat yarn made of polyethylene gas pipe waste materials is split into narrow breadth to obtain tapes as warps and wefts that are to be plainly woven into a long sheet. A laminated sheet formed by a polyethylene film integrally bonding to at least one surface of the long sheet, is fold back n times (n is 2 or 4) in its longitudinal direction in the same length so as to obtain a sheet wherein (n+1) piled portions and non-piled portions are alternately continuous with each other. The sheets of piled portions are releasably attached.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sign sheet formed by using waste polyethylene gas pipes indicating the location of a buried polyethylene gas pipe and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, steel pipes or cast iron gas pipes have been used as pipes for city gas buried underground. Buried conventional gas pipes with poor flexibility may be damaged by shock or vibration of heavy vehicles due to corrosion, earthquakes, etc. In recent years, they are rich in flexibility, corrosion resistance and strength. Excellent, light and work-friendly polyethylene gas pipes have been used. When burying polyethylene gas pipes, workers can easily check the burial position of gas pipes when digging a road, etc. due to road work, construction work, renewal of gas pipes or other circumstances after burying, A sign sheet indicating the location of the buried gas pipe is laid along the gas pipe between the buried gas pipe and the ground surface so as not to damage the pipe.

[0003]

As the above-mentioned marker sheet, a tape made of virgin (new material) polyethylene (PE) or propylene (PP) as a raw material, and a flat yarn colored green or the like is narrowly split. Laminated plain woven sheet (woven fabric) (Japanese Patent Laid-Open No. Hei 6-337090), tape using waste gas pipe made of PE and virgin H
A two-layer laminated tape in which a DPE tape is laminated or a plain woven sheet in which a three-layer laminated tape in which a virgin HDPE tape is laminated on both outer layers are vertically and horizontally folded (Japanese Patent Laid-Open No. 7-309959) is used. ing. All of these are economically disadvantageous because virgin PE and PP are used.

[0004] By the way, the end of the polyethylene gas pipe is cut off in order to adjust the length of the gas pipe formed in a prescribed size at the construction site in order to perform the piping work. The end of the polyethylene gas pipe is incinerated or crushed without being recycled as waste material, and is disposed of by landfill. Therefore, disposal of this waste material is a waste of resources, and it is necessary to effectively utilize this waste material in some way. SUMMARY OF THE INVENTION The present invention provides a sign sheet for a buried polyethylene gas pipe using waste polyethylene gas pipes and a method for manufacturing the same, with the object of effectively utilizing waste polyethylene gas pipes and reducing the volume of waste. That is.

[0005]

The above object is achieved by the present invention described below. That is, the present invention integrally joins a polyethylene film to at least one surface of a long sheet formed by flat weaving a flat yarn containing a waste gas pipe made of polyethylene into a narrow width as a warp and a weft, respectively. (N + 1) laminated portions and one non-overlapping portion are alternately and continuously formed at the same length in the length direction of the laminated sheet. A buried polyethylene gas pipe marking sheet, characterized in that the overlapped portion of the finished sheet is releasably fixed, and a method of manufacturing the same.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The buried polyethylene (P)
E) The gas tube marker sheet (hereinafter sometimes simply referred to as a marker sheet) will be described with reference to the drawings. FIG. 2 shows an example of the sign sheet of the present invention in the case where n is 2. A wide sheet having a width of, for example, about 15 cm is shown in FIG.
It is folded twice at a length x in the length direction and a three-layered portion 1
Is formed, and then the one-piece part 2 having a length x and not being folded is left, and the three-ply part 1 and the one-piece part 2 are formed alternately and continuously. It is a long sheet having a length of about 50 m, which is continuously and linearly peelably fused along the length direction.

[0007] The above-mentioned releasably fixed overlapping portion 1 is provided above a PE gas pipe when a road is excavated by a power shovel or the like for road construction or gas pipe construction. When the sign sheet is hooked by a power shovel or the like, if there is no overlapping part, the sign sheet will be cut and it will be difficult to check the buried PE gas pipe, but if there is the above overlapping part, the overlapping part will peel off. This is because the location of the gas pipe can be confirmed by being pulled by a power shovel or the like without being cut. If the overlapping portion is firmly fixed, it is cut off at one overlapping portion without peeling. The peelable fixation of the overlapped portion is not limited to fusion, but does not peel off during laying work such as sewing sewing with fiber thread whose strength decreases due to corrosion etc. after laying, and peels off due to the above action when digging up the road surface Any means may be used as long as the means performs the processing.

[0008] The sign sheet of the present invention is formed by using, as a main component, waste material such as the end of a PE gas pipe cut for length adjustment or the like in gas pipe piping work. . For the PE gas pipe, for example, a medium density polyethylene (for example, having a density of 0.935 g / cm ³ or the like) or a PE mixture obtained by mixing an appropriate amount of high density to low density polyethylene is used. However, the type of PE as the gas tube forming material is not particularly limited. Further, the PE gas pipe is usually colored light green or yellow.

In producing the marker sheet of the present invention, P
The waste material of the gas pipe made of E is washed, if necessary, pulverized by an appropriate means, and then pelletized at a temperature of, for example, 170 to 200 ° C. by an extruder or a pelletizer and used. Waste gas pipe made of PE is unavoidable to be mixed with impurities, and it is difficult to obtain a buried PE gas pipe marker sheet having a sufficient strength by using it alone. Used by mixing with PE. The mixing ratio of the waste material and the virgin PE differs depending on the degree of mixing of impurities in the waste material, and cannot be specified unconditionally, and needs to be appropriately determined according to the waste material used. The mixing ratio of the waste material is, for example, less than 50% by weight to 35% by weight.
It is about. As virgin PE, high density or low density P
Any type of PE, such as E, can be used. Low-density PEs include those commonly referred to as LDPE and LLDPE
(Linear low-density PE), any of which can be used.

The mixed PE is obtained by mixing the waste material and the new material PE while melting them using, for example, a twin-screw extruder, and is usually used in the form of pellets. At the time of mixing, conventionally known additives such as an antioxidant, a lubricant, a flame retardant, and a green or yellow pigment can be appropriately added.

The step of forming a wide and long sheet made by plain weaving a tape obtained by splitting a narrow yarn of polyethylene flat yarn containing waste gas pipe made of polyethylene into narrow widths as warp and weft, respectively (1). Step (2) of laminating a polyethylene film on at least one surface and joining the sheet integrally with the sheet, the laminated sheet obtained in the step (2) is made to have the same length in the length direction, and n (n is 2 or 4) Steps (3) and (3) of alternately and successively forming the (n + 1) overlapping portions and the one non-overlapping portion which are repeatedly bent.
The step (4) of fixing the overlapped portion of the sheet obtained in step (1) in a releasable linear manner can be carried out continuously or by performing each step individually.

In order to produce the sign sheet of the present invention,
First, the thickness of the above PE mixture by flat die molding or inflation molding, for example, 0.02 to 0.3
It is formed into a film of about mm. A flat yarn is produced by a method of forming a film, slitting, stretching and heat-treating and winding the film, or a method of stretching and heat-treating the film as it is and slitting and winding it.

Next, the flat yarn is split (split) on a narrow tape of about 3 to 5 mm by a known method such as a splitter, and the split tape is used as a warp and a weft as shown in FIG. 1 by known means. Plain woven sheet (woven fabric). Further, a new polyethylene film (having a thickness of about 0.01 to 0.2 mm) is laminated on one side of the plain woven sheet for reinforcement and to prevent looseness of warp and weft yarns.
Next, this laminate sheet is cut into a width of about 15 cm to form a plain woven sheet base material.

This plain woven sheet is folded twice or four times in the length direction, and the length is, for example, 3 or 5 overlapped portions 1 of about 9 cm. 2 and 3 are alternately and continuously processed, and three or five overlapping portions are fixed in a releasable manner by an appropriate means, for example, a linear portion at the center of the width is continuously or discontinuously. In addition, when plain weaving, the thickness of the warp and the weft can be changed. For example, the above-described narrow tape having the same thickness in the warp and the weft is used, and the warp in the sheet length direction is obtained by stacking at least two pieces of the above-described split tape. In addition, at least one weft yarn can be used to perform plain weaving by increasing the number of warp split tapes to be greater than that of the weft yarn, and a sign sheet having excellent strength in the length direction can be obtained by using such a plain woven sheet. It is preferred.

As the polyethylene film to be laminated on the plain woven sheet, low-density PE, ionomer (for example, Na salt of ethylene-acrylic acid copolymer, K
For example, a film of a polyethylene copolymer containing a carboxyl group, for example, an ionomer, is preferred from the viewpoint of adhesion to the plain fabric. For laminating a plain woven sheet and a polyethylene film, for example, a conventionally known method such as extruding a polyethylene film from a T-die of an extruder onto a plain woven sheet, passing the plain woven sheet and the polyethylene film between heating rolls, or the like. A lamination method can be used, and the lamination method is not particularly limited.

[0016]

Next, the present invention will be described more specifically with reference to examples.

Example 1 Pellets of a PE mixture of 45% by weight of waste gas pipe made of PE and 55% by weight of virgin LDPE were kneaded and extruded in a molten state using a twin-screw extruder to produce a pellet. Using the pellets, a film having a thickness of about 0.05 mm was formed by inflation molding (die temperature 200 ° C.), slit, stretched about 7 times at 85 to 100 ° C., heat-treated at the same temperature, and wound up. . The flat yarn obtained above was slit to a width of about 3 mm with a splitter to produce a plain weave tape (warp and weft). Using a plain weaving machine, two sheets of the above-mentioned tape were piled up for warp, and a plain weave sheet having a width of 2 m and a length of 10 m was formed with one weft. Next, a film having a thickness of about 0.03 mm of an ionomer (manufactured by DuPont) is laminated on a plain woven sheet with a laminator to integrate the two, and this laminated sheet is cut into a width of about 15 cm to obtain a label sheet of the present invention. A substrate was prepared and wound.

While pulling out the base material sheet from the above-mentioned wound material, the base material sheet is folded at an appropriate length from the end in the pulling-out direction, and the base material sheet is wound again with a length of about 9 cm (x in FIG. 2). It is folded back to the object side to form a portion (1 in FIG. 2) where three base tapes are overlapped, and a length of about 9 cm from this portion is set to the above-mentioned one tape portion (2 in FIG. 2). The operation was sequentially repeated, and three overlapping portions and one portion were alternately formed continuously up to the terminal portion of the base sheet. The center of the width of the overlapping portion of the tape was linearly fused in a spot manner to obtain a sign sheet of the present invention. After laying this sign sheet in parallel with the ground surface and pressing the soil sufficiently,
When pulled up with a power shovel, the sign sheet was not cut, but the overlapped portion was peeled off and pulled one after another, confirming that the sign sheet worked sufficiently. A plain woven sheet having no overlapped portion was laid in the same manner and pulled up with a power shovel in the same manner as described above, but it could not be cut and dragged.

[0019]

According to the present invention described above, when excavating a road surface, even if it is lifted up by a power shovel or the like, it can be easily pulled in without cutting, and the presence of a buried PE gas pipe can be confirmed. A gas tube marking sheet is provided.

[Brief description of the drawings]

FIG. 1 is a schematic plan view illustrating a plain fabric.

FIG. 2 is a perspective view illustrating the sign tape of the present invention.

[Explanation of symbols]

 1: 3 sheet overlap part 2: 1 sheet part x: Length of each part

Claims (4)

[Claims] 1. A long sheet formed by flat weaving a tape obtained by splitting a flat yarn containing waste gas pipe made of polyethylene into a narrow width as warp and weft, respectively, and integrally joining a polyethylene film to at least one surface of the long sheet. The laminated sheet is folded n times (n is 2 or 4) to the same length in the length direction (n + 2).
1) A buried polyethylene gas pipe marker sheet, characterized in that the above-mentioned superposed portion of a sheet in which a superposed portion and a single non-overlapping portion are alternately and continuously formed is releasably fixed. 2. The plain woven sheet according to claim 1, wherein the number of warp split tapes is greater than the number of warp yarns, the warp yarns being formed by warp yarns obtained by stacking at least two split tapes and at least one weft yarn. Item 1
2. A gas pipe marker sheet made of buried polyethylene according to item 1. 3. The buried polyethylene gas pipe marker according to claim 1, wherein the flat yarn is formed of a mixture of less than 50% by weight of waste polyethylene gas pipe and more than 50% by weight of virgin (new material) polyethylene. Sheet. 4. A wide width obtained by flat weaving tapes obtained by splitting flat yarns containing waste polyethylene gas pipes into narrow widths as warp yarns and weft yarns, respectively, in producing a marking tape indicating the presence of embedded polyethylene gas pipes. Step (1) of forming a long sheet, step (2) of laminating a polyethylene film on at least one surface of the sheet and joining integrally with the sheet, and step (2) of obtaining the laminated sheet obtained in step (2) (3), a step of alternately and continuously forming a (n + 1) -layered portion and a non-overlapping one-layer portion, which are n-folded (n is 2 or 4) in the same direction in the same direction. The step (4) of releasably fixing the overlapping portion of the sheet obtained in (3) is performed continuously or independently. Of producing a buried polyethylene gas pipe sign sheet.