JPH0326309B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a buried object marker that is buried near an underground object to indicate the presence of the object when the ground is excavated.

[Prior art]

Gas pipes, water and sewage pipes, power lines buried underground,
When repairing buried objects such as communication lines, or burying other buried objects such as piping nearby, it is necessary to dig up the ground, but at this time it is necessary to prevent the buried objects from being damaged by power shovels, etc. For,
A sign that prints information such as the type of buried object, its specifications, burial period, warnings, etc. is buried above the buried object. As a conventional buried object marker of this type, there is one in which a synthetic resin film is folded in at intervals in the longitudinal direction and spot welded at the overlapping parts.

However, conventional buried object markers are made of low-density polyethylene film or polyvinyl chloride film, so they have low strength. The disadvantage was that it often broke and went undetected by workers on the ground.

[Purpose of the invention]

This invention is intended to improve the above-mentioned conventional drawbacks, and is made of a woven fabric made of a stretched tape of a high-density polyethylene film having specific physical properties, and a woven fabric made of a stretched tape of a low-density polyethylene film having specific physical properties. By using a laminate sheet that is bonded to a display film through an intermediate adhesive layer made of low-density polyethylene that has specific physical properties, it has high strength, excellent folding and welding properties, and is easy to use when digging. It is an object of the present invention to provide a buried object sign whose folded part can be appropriately extended to reliably indicate the location of the buried object without being damaged.

[Structure of the invention]

This invention consists of a woven fabric made of a stretched tape made by stretching a high-density polyethylene film with a density of 0.940 g/cm ³ or more and a melt flow index of 0.1 to 3 g/10 min at a magnification of 5 to 10 times, and a woven fabric with a density of 0.930 g/cm ³ In the following, a display film made of low density polyethylene with a melt flow index of 0.5 to 8 g/min is interfused with an intermediate fusion film made of low density polyethylene with a density of 0.924 g/cm ³ or less and a melt flow index of 3 to 12 g/10 min. A buried object consisting of a laminate sheet pasted together through layers, the laminate sheet having overlapping parts folded in at intervals in the longitudinal direction, and having partial welded parts in the overlapping parts. It is a sign.

The present invention will be explained below with reference to the drawings. The drawings show examples, and FIG. 1 is a cross-sectional view of a laminate sheet.
FIG. 2 is a perspective view of the sign.

Laminate sheet 1 used in the present invention
In this case, the woven fabric 2 and the display film 3 are connected to the intermediate adhesive layer 4.
It has a structure in which it is laminated with a . Woven fabric 2
has a density of 0.940g/cm3 ^or more, preferably 0.951~
0.954g/cm ³ , melt flow index (below)
MFI) 0.1~3g/10min, preferably 0.65~
This cloth is made by slitting a 0.9 g/10 min high-density polyethylene film, heating and stretching the stretched tape 5 to a magnification of 5 to 10 times, and weaving it using a normal loom such as an ordinary loom or an innovative loom.

The above-mentioned stretched tape 5 has a strength of approximately 5 g/denier, approximately 4000 kg/cm ² per unit area, and approximately
The strength has increased to more than ten times that of 300Kg/ ^cm2 , and the strength of the woven fabric 2 made from this is greater than that of the raw resin film, and it has good chemical resistance, so it has good durability underground. It is large and has excellent fusion properties with the intermediate fusion layer 4. Density of raw resin and
The reason why MFI is limited is that if the density is less than 0.940g/ ^cm3 , the strength will decrease, if the MFI is less than 0.1g/10min, the extrusion rate will decrease, and if the MFI exceeds 3g/10min, the inflation method will be used. This is because bubbles are unstable during fabric forming and easily break during weaving.

The stretched tape 5 is formed by slitting a film made of the above-mentioned high-density polyethylene into a predetermined width using a razor blade, a rotary blade, etc., and heating and stretching it at a temperature range below the melting point of the raw resin and above the secondary dislocation point. Ru. Stretching is carried out by changing the circumferential speed of the nip rolls on the inlet and outlet sides of the heating device, and the stretching ratio is generally 5 to 10 times, preferably 6 to 8 times. If the draw ratio is too low, strength cannot be obtained, and if the draw ratio is too high, the threads tend to separate, resulting in poor weavability. The method of weaving the stretched tape 5 is not particularly limited.

The display film 3 has a density of 0.930 g/cm ³ or less, preferably 0.921 to 0.922 g/cm ^{3 , and an MFI of 0.5 to 8 g/cm 3} .
10 min, preferably 2.7 to 3.3 g/10 min, is made of a low density polyethylene film, and on the back side (intermediate adhesive layer 4 side) is a display section with letters, pictures, etc. printed with the type of buried object, standards, burial time, and warnings. 6 is formed. The reason why the density and MFI of the raw resin are limited is that when the density exceeds 0.930 g/cm ³ , the foldability of the laminate sheet 1 deteriorates, and when the MFI is 0.5 g/cm 3
If it is less than 10 min, the extrusion rate will decrease and the MFI will decrease.
This is because if it exceeds 8 g/10 min, the printed display part 6 is likely to be disturbed due to the tension during lamination.

These woven fabric 2 and display film 3 are pasted together via an intermediate adhesive layer 4 to form a laminate sheet 1. The intermediate adhesive layer 4 has a density of 0.924 g/cm ³ or less, preferably 0.922 to 0.923 g/cm ³ , and MFI3 to
It is made of low density polyethylene of 12g/10min, preferably 3.3-3.8g/10min. The reason why the density and MFI of the raw resin are limited is that the density
If it exceeds 0.924g/ ^cm3 , the foldability will deteriorate and the MFI will decrease.
This is because if the MFI is less than 3 g/10 min, the melting temperature must be increased, and the orientation of the woven fabric 2 is relaxed compared to the laminate, resulting in a decrease in strength, and if the MFI exceeds 12 g/10 min, uneven thickness tends to occur.

It is preferable that the woven fabric 2 and the display film 3 be laminated together using an extruded laminate sheet, but dry lamination or other methods may also be used. In this case, since the intermediate fusion layer 4 is formed through the display section 6, it is desirable that the display section 6 be formed of a material with good fusion properties. When the display section 6 is formed on the surface (outside) of the display film 3, the material thereof is selected in consideration of its fusion properties with the display film 3 and its durability underground.

In the sign 7 of the present invention, as shown in FIG. A welded part 10 is formed by spot welding or the like in the overlapping part 9 formed as a result. The folding magnification, that is, the magnification at which the laminate sheet 1 stretches when the welded part 10 is destroyed, is:
It is usually 2 to 4 times higher, but it can be arbitrarily determined depending on the location, soil quality, etc. In FIG. 2, the folding method is such that the tip of the folding part 8 overlaps with the adjacent folding part 8, but depending on the folding magnification, a folding method that does not overlap is also possible. Moreover, the polymerization part 9 is usually 3
Although it is assumed to be a stack of sheets or a stack of five sheets, it is not limited to these.

The welded portion 10 is not limited to a spot shape, but may be formed by partially welding the overlapping portion 9, such as a broken line shape. In FIG. 2, the ends of the folded part 8 on both sides overlap, so a welded part 10 is formed at that end. A welded portion 10 can be formed in the portion. It is desirable that the overlapping portion 10 be formed to withstand the tension during burying and to be easily destroyed during excavation.

The sign 7 configured as described above becomes a sign embedded near an underground object such as a gas pipe (usually above the object) to indicate the location of the object. When the buried object is caught by a power shovel or the like during excavation, the welded portion 10 is destroyed and the laminate sheet 1 is expanded to indicate the location of the buried object.

At this time, since the strength of the laminate sheet 1 is high, even if the buried soil hardens, the laminate sheet 1
is pulled out without being cut in the middle, and the folding part 8
The mark 7 is extended by partially or completely being released, and the location of the buried object can be reliably indicated. In addition, the woven fabric 2, the display film 3, and the intermediate adhesive layer 4, which are the materials of the laminate sheet 1, all have great durability underground, and because they are buried in a composite state, there is little loss of strength. Can be used for a long time. Further, when the surface portion 6 is provided on the back side of the display film 3, durability under the ground is increased, and accurate display can be performed over a long period of time.

In the above explanation, laminate sheet 1
There is no problem in providing another film or the like in the middle or on the outer surface of the woven fabric 2, display film 3, and intermediate adhesive layer 4, or forming the display section 6 at a position other than the back surface. Furthermore, the folding method, polymerization method, etc. of the label 7 are not limited to those shown in the drawings.

[Embodiments of the invention]

Example A film with a thickness of 47 μm was formed using high-density polyethylene with a density of 0.953 g/cm ³ and an MFI of 0.80 g/10 min, which was slit and stretched 7 times at a stretching temperature of 110° C. to 1500 denier. A stretched tape with a strength of 5.0 g/denier was produced and woven into a length of 14 pieces/inch by a loom of 12 pieces/inch to obtain the woven fabric 2 shown in FIG. The strength of this woven fabric 2 was 165 kg/5 cm in length and 155 kg/5 cm in width.

On the other hand, a display part 6 was formed by printing on the back side of a display film 3 made of a 40μ thick film made of low-density polyethylene with a density of 0.921g/cm ³ and an MFI of 3.0g/10min. , density 0.923g/cm ³ ,
Extrusion lamination sheet is pasted through low density polyethylene with MFI3.5g/10min, thickness
Laminate sheet 1 with 30μ intermediate adhesive layer 4
was formed.

The obtained laminate sheet 1 is slit to a width of 150 mm, folded 3.5 times as much as shown in Fig. 2, and welded parts 10 are formed by spot welding two places each at the overlapping part 9.
was formed to obtain label 7. The peel strength in the longitudinal direction of the sheet of the welded part 10 of the obtained sign 7 was 5.5 kg.
(Tensile speed: 20 cm/min, the same applies hereafter), and the strength in the longitudinal direction of the laminate sheet 1 was 168 kg/5 cm width (Tensile speed: 20 cm/min, the same applies below).

When this sign 7 was buried 50 cm underground and excavated with a power shovel at a later date, it was confirmed that the welded part 10 of the sign 7 peeled off and the overlapping part 9 did not stretch and be cut, making it possible to use it as a buried object sign. Ta.

Comparative Example 1 Only display film 3 in Example (however,
The peel strength in the longitudinal direction of the welded part of the sheet of the sign folded in the same manner as in Example was 2.9 kg, and the strength of the display film 3 was 14 kg/5 cm width.

This sign was buried 50cm underground, and when it was dug up with a power shovel later, the sign was cut off.

Comparative Example 2 The same procedure was carried out except that polyethylene with a density of 0.934 g/cm ³ and MFI of 0.80 g/10 min was used instead of the polyethylene for the woven fabric in Example, and the results were as follows: Peel strength is 2.5Kg,
The strength of the laminate sheet was 90 kg/5 cm width.

When this sign was buried 50cm underground and later excavated using a power shovel, it was found that more than half of the sign had been cut in the width direction.

〔Effect of the invention〕

According to the present invention, a woven fabric made of a stretched tape of a film made of high-density polyethylene having specific physical properties, and an indicator film made of a film made of low-density polyethylene having specific physical properties, The laminate sheets pasted together through an intermediate adhesive layer are folded together, and the overlapping parts are welded together, resulting in high strength, excellent folding and welding properties, and no damage when excavated. The folded portion extends to reliably display the location of buried objects, and has high durability underground, allowing accurate display over a long period of time.

[Brief explanation of the drawing]

1 and 2 show examples, with FIG. 1 being a sectional view of a laminate sheet, and FIG. 2 being a perspective view of a sign. 1... Laminate sheet, 2... Woven fabric, 3...
Display film, 4... Intermediate adhesive layer, 5... Stretched tape, 6... Display section, 7... Label, 8... Folding section, 9... Polymerization section, 10... Welding section.

Claims (1)

[Claims] 1. A woven fabric made of a stretched tape made by stretching a high-density polyethylene film with a density of 0.940 g/cm ³ or more and a melt flow index of 0.1 to 3 g/10 min at a magnification of 5 to 10 times, and a density of 0.930 g. / cm ³ or less and a melt flow index of 0.5 to 8 g/10 min.
Melt flow index 3~ below 0.924g/ ^cm3
Consists of laminate sheets laminated together via an intermediate adhesive layer made of 12g/10min low-density polyethylene, and this laminate sheet has overlapping parts folded in at intervals in the longitudinal direction, and partially A buried object marker characterized by having a welded part. 2. The buried object marker according to claim 1, wherein the stretched tape is obtained by slitting a film and then stretching it. 3. The buried object marker according to claim 1 or 2, wherein the display film has a display portion printed on the intermediate adhesive layer side. 4. The buried object marker according to any one of claims 1 to 3, wherein the intermediate adhesive layer is formed of an extruded laminate sheet. 5. The buried object marker according to any one of claims 1 to 4, wherein the welded portion is formed by spot welding.