JPH1031446A - Underground embedded object sign sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an underground embedded object sign sheet which forms display part having sufficient durability is inexpensively predicable with decreased production stages, prevents the damage at excavation, and is capable of surely displaying the presence of an underground embedded object by extending the folding part properly. SOLUTION: This sign sheet consists of laminated sheets 2 of two layers; a base fabric layer 5 which is formed by using composite flat yarn 8 obtd. by using a first polyolefin resin as a core layer and forming outside layers by a second polyolefin resin having a m.p. or softening point lower than the m.p. or softening point of the first polyolefin resin as at least either of warp and weft, and weaving this flat yarn on both surfaces of the core layer, then fusing the intersected parts of the warp and weft by a heat treatment and a protective layer 7 which coats a printing surface 6 formed by normal character printing the desired display characters directly on the surface of this base fabric layer 5. The folded parts formed by folding the sheets at intervals in a longitudinal direction are formed at the laminated sheets 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of burying a gas pipe, a water pipe, a power cable, a communication cable, and the like buried in the ground near a buried object, and excavating the ground for work later. At this time, the present invention relates to an underground object marking sheet for notifying the existence of an object.

[0002]

2. Description of the Related Art As this kind of sign sheet, there is Japanese Utility Model Publication No. 50
As described in No. -30801 publication, in the past, display characters were printed on the surface of a soft synthetic resin sheet such as polyolefin or polyvinyl chloride, and the printed surface was covered with a protective layer, but the strength was particularly small. In a buried state that is firmly tightened in the ground, it breaks due to contact during excavation of a machine such as a power shovel, and is often not detected by workers, and the original purpose of calling attention may not be achieved. Was. Therefore, a woven fabric consisting of stretch-oriented high-strength synthetic fibers is used as the base material of the sign sheet as a material that has strength that will not be easily damaged during excavation. Therefore, those having a function of extending when hooked on a machine or the like are generally used.

[0003] The marker sheet using the synthetic fiber woven fabric as a base material has a structure in which a film on which display characters are printed in advance is laminated. In other words, the surface of the woven fabric has large irregularities due to the intersection of the yarns of the course, and the printing of display characters requires considerable pressurization, making continuous printing difficult with normal roll printing, and the printing ink printing. This is because a large amount of coating is required, and the finished state of printing naturally has a problem that characters are unclear. Also, if the printed surface on the film is on the outermost surface of the sign sheet, the display characters may be eroded during the burying period of the sign sheet and the display may not be identifiable. For example, when laminating a transparent film on the surface of a sheet woven with a synthetic resin tape, display characters are printed in reverse characters on the back surface of the film, and a structure that allows normal display characters to be read through the film layer (Japanese Patent Publication No. 55-40877) or a sheet made of a specific woven fabric, an adhesive layer, and a display film, and the display film has a display portion printed in reverse on the adhesive layer side (Japanese Patent Publication No. -Five
No. 4596), and a protective sheet to be laminated on a base sheet, a normal character printed on the surface of the film, and a multi-layered sign sheet further coated with a protective layer (Japanese Utility Model Publication No. 3-31909) is disclosed. .

[0004] Forming display characters by printing on a film in the opposite direction requires the production of a special plate in accordance with the characters, which is a factor of low productivity and high cost. In addition, if the display characters are formed by printing the characters on the film to form the display characters, at least a surface coating step is required in addition to the bonding step with the woven fabric, and the production process is increased. It cannot be denied.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and has as its main object the formation of a highly durable display section. An object of the present invention is to provide an underground buried object marking sheet that is capable of reliably displaying the presence of a buried object by being able to prevent breakage at the time of excavation and extending the fold portion appropriately.

[0006]

According to the present invention, a first polyolefin-based resin is used as a core layer, and an outer layer is formed on both surfaces thereof with a second polyolefin-based resin having a lower melting point or softening point than that of the first polyolefin-based resin. The formed composite flat yarn was woven using at least one of the weft strips, and then the base cloth layer where the weft intersection was fused by heat treatment, and the desired display characters were printed with the normal characters directly on the surface of the base cloth layer. The underground object marking sheet is composed of a two-layer laminate sheet with a protective layer covering the printing surface, and the laminate sheet is formed by forming a folded portion that is folded at intervals in the longitudinal direction.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a partially enlarged cross-sectional view showing a laminate sheet used for a sign sheet.
(a) shows a base fabric layer, (b) shows a printed surface on the base fabric layer, and (c) shows a laminate sheet having a protective layer and two layers. FIG. 2 is an enlarged sectional view showing a composite flat yarn used for a sign sheet.

The laminate sheet 2 constituting the sign sheet according to the present invention comprises a base cloth layer 5 and a protective layer 7 on a printing surface 6 as shown in FIGS. Actually, it is composed of a two-layer laminated structure in which the printing surface of a flat yarn woven fabric on which a normal character is printed is coated with a resin.

The woven fabric to be the base fabric layer 5 in the present invention is woven using a composite flat yarn 8 which is a drawn yarn made of a polyolefin resin. Here, the composite flat yarn 8 is, as schematically shown in FIG.
A first polyolefin-based resin core layer 81 composed of a high-melting-point component laminated by a multi-layer T-die flat method or an inflation method or laminated by a sequential extrusion laminating method, and a second layer composed of a low-melting-point component A three-layer film composed of an outer layer 82 of a polyolefin resin is slit into a predetermined width to form a tape, stretched uniaxially by a hot plate or a hot roll, oriented, and then subjected to an annealing treatment. Flat yarn.

[0010] The polyolefin resin used for the composite flat yarn 8 is selected from the viewpoint of stable quality of continuous production and economical mass production at low cost among thermoplastic resins. Preferred examples of the first polyolefin-based resin to be the layer 81 include high-density polyethylene,
Examples of the second polyolefin-based resin that forms the outer layer 82 include ultra-low-density polyethylene, low-density polyethylene, linear low-density polyethylene, and ethylene-acetic acid. Vinyl copolymer, ethylene-acrylic acid copolymer, ethylene-
A propylene copolymer and the like can be mentioned. In these combinations, the temperature difference between the melting point and the softening point of the first polyolefin-based resin and the second polyolefin-based resin is 10 ° C or more, preferably 15 to 25 ° C. By this appropriate temperature difference, the weft cloth, which will be described later, can be firmly bonded without causing thermal deterioration at the weft intersection.

The composite flat yarn 8 is woven using a known loom such as a circular loom, a Sulzer loom, or a water jet loom to form a woven fabric. The flat yarn woven fabric is preferably woven by densely driving the weft with flat yarn. Here, dense weaving means that the gap between adjacent warps or wefts is as small as possible, and the overlapping portions are small and high-density driving is performed. Flat yarn is a tape-like thin material having a thickness of about 20 to 50 μm in synthetic fibers.By weaving this flat flat yarn by reducing the gap between adjacent yarns, a woven fabric is formed. Surface irregularities can be reduced and a relatively smooth state can be achieved. In order to further improve the smoothness, it is preferable to use flat yarns that are not folded in the width direction.Flat yarns having a width of 1.8 to 5.0 mm are usually used in a plain weave structure with a driving density of about 5 to 14 yarns / inch. It is desirable to weave.

FIG. 1 (a) shows an embodiment in which a composite flat yarn 8 is used for both the warp and the weft, but this is the most preferable form for firmly heat-sealing the warp-weft intersection by a subsequent heat treatment. However, it is also possible to use a composite flat yarn for only one of the warp and the weft. That is, the low-melting-point component of one of the yarns forming the weft intersection is softened and melted, and thus adheres to the other yarn to serve as a seal. Therefore, as the yarn other than the composite flat yarn, a single-layer flat yarn made of the polyolefin resin exemplified as the high melting point component described above is employed.

As the heat treatment for filling the flat yarn woven fabric, known devices or methods such as a hot plate contact type, a hot roll type, an infrared irradiation type, a high frequency welder type, and a hot air oven type are employed. However, the heat treatment temperature is set in the temperature range below the melting point of the high melting point component constituting the composite flat yarn and above the softening point of the low melting point component. It is important to wear them. In this way, if the weft intersection is fixed by heat-sealing and used, there will be no yarn floating, curving, or fraying of the edge of the woven fabric, and the base fabric layer 5 will be easily handled in post-processing.

Next, as shown in FIG. 1 (b), desired display characters such as the type and standard of the buried object, burying time, warning, and contact information are directly provided on the surface of the base cloth layer 5. Printing is performed with regular characters, and the printing surface 6 is formed. Although this printing method is not particularly limited, it is normal character printing, and therefore does not require a special plate such as reverse character printing.

Further, as shown in FIG. 1C, a transparent protective layer 7 is formed on the surface of the printing surface 6 by a melt extrusion lamination method. The laminating resin used as the protective layer 7 has a low melting point because it suppresses thermal deterioration of the base material, has good adhesiveness so as to be firmly joined, and has transparency enough to allow display characters to be confirmed through the coating. As low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, maleic anhydride polyolefin, ethylene-
A propylene copolymer or the like is used. The thickness of the protective layer 7 is preferably in the range of 30 to 60 μm from the viewpoint of protecting the printing surface 6 and improving the mechanical strength of the substrate. That is, if the thickness is less than 30 μm, the protective effect of the printing surface 6 is insufficient, while if the thickness is more than 60 μm, the flexibility as a laminate is hindered, which impairs the workability of folding and folding. Can be considered.

Since the laminate sheet 2 composed of the base layer 5, the printing surface 6 and the protective layer 7 is used for a sign sheet, it is designed to prevent breakage easily, especially by contact with machinery after embedding. In order not to break, the tensile strength in the longitudinal direction needs to be 80 kgf / 5 cm or more. On the other hand, the strength in the width direction is not so required as in the longitudinal direction, and the object can be sufficiently achieved even in about 4/5 to 1/2 of the longitudinal direction.

FIG. 3 is a perspective view showing an example of the form of the sign sheet 1. As shown in FIG. The laminated sheet 2 is formed with the folded portions 3 formed at intervals in the longitudinal direction, and is provided with a fixing means to maintain the folded portions 3 in the overlapped state, thereby forming the sign sheet 1. Here, the fold fixing part 4 for maintaining the state of the fold part 3 is necessary for handling of the sign sheet 1 or for transporting and storing the sign sheet 1. It must be constructed so that it can be easily broken and extended so as not to cause resistance. Accordingly, it is possible to employ a fold-fixing means such as partial spot welding or linear partial welding that can be easily peeled off, or sewing with synthetic fibers or corrosive fibers.

In the case where the fold-fixing portion 4 is formed by utilizing the heat-fusing property of the laminate sheet 2, if the base material is laminated on one surface of the base material, the fold portion 3 has a contact between the base material surfaces. They will be in contact or the laminated surfaces will be in contact. Of these, the portions where the substrate surfaces of the relatively high melting point components abut each other need to be thermally bonded at a high temperature, and this heating may cause a decrease in strength due to thermal deterioration, but is used in the present invention. Although the laminated sheet 2 is a single-sided laminated product, the outer layer 82 of the composite flat yarn 8 always has a low melting point component exposed on the substrate surface, so that heat fusion at a relatively low temperature becomes possible. Thermal degradation can be suppressed.

The sign sheet 1 thus obtained is buried in the ground above the buried object and serves as a sign indicating the location of the buried object. In other words, when excavating the ground surface, if it is hooked on a power shovel or the like, the fold fixing portion 4 is broken, the fold portion 3 is extended, and the base material is pulled out to the ground surface without being cut off, and the operator is displayed on the sheet with characters displayed on the sheet. It will surely tell you what buried objects are nearby.

[0020]

【Example】

Example 1 Polypropylene having a melting point of 138 ° C. was used as a resin for the core layer, and an ethylene-acrylic acid copolymer having a melting point of 108 ° C. (AA content)
10%) as the resin for the outer layer, and put into each of the two series of extruders to form a three-layer film (layer ratio 1: 8: 1) by co-extrusion inflation molding, then slit and tape. And stretched 5 times in the machine direction to obtain a yarn width of 2.5m
m and a composite flat yarn 8 having a fineness of 1,000 dr were obtained.

The composite flat yarn 8 is used as a warp yarn and woven by a sulzer type loom with a plain weave structure having a driving density of 10 × 10 yarns / inch. The base cloth layer 5 was formed.

On the surface of the base fabric layer 5, desired display characters are directly printed with normal characters to form a printing surface 6, and a linear low-density polyethylene having a thickness of 50 μm is formed on the surface by melt extrusion lamination. By coating, a protective layer 7 was formed to form a laminate sheet 2. The tensile strength of the laminate sheet 2 was 87 kgf / 5 cm in the warp direction and 80 kgf / 5 cm in the weft direction.

After the laminate sheet 2 is slit to a width of 150 mm, a folded portion 3 is formed so as to have an elongation ratio of about 2 times, and the center position in the sheet width direction is continuously formed in the longitudinal direction by a high-frequency fusion method. The heat-sealing was performed to form the fold-fixing portion 4 to obtain the sign sheet of Example 1. The peel strength of the fold 3 was 3.8 kgf.

Example 2 High-density polyethylene having a melting point of 130 ° C. was used as the resin for the core layer, and ethylene-vinyl acetate copolymer (VA
(Content 10%) as the resin of the outer layer, and put into each of two series of extruders to form a three-layer film (layer ratio 1: 8: 1) by co-extrusion inflation molding method, and then slit. It is made into a tape shape, stretched 5 times in the longitudinal direction, and the yarn width
A composite flat yarn 8 having a diameter of 2.1 mm and a fineness of 800 dr was obtained.

The composite flat yarn 8 is used as a weft,
Using a single-layer flat yarn made of high-density polyethylene with a yarn width of 2.5 mm and a fineness of 1,000 dr as the warp, weaving it with a sulzer-type loom in a plain weave structure with a driving density of 10 x 12 yarns / inch, and then heat-treating by infrared irradiation. At a temperature of 115 ° C., the process intersection was thermally fused to form a base fabric layer 5.

A printing surface 6 and a protective layer 7 are formed on the base fabric layer 5 to form a two-layer laminate sheet 2 in the same manner as in Example 1, and a folded portion is formed and heat-sealed. The sign sheet of Example 2 was obtained. The tensile strength of the laminate sheet 2 was 95 kgf / 5 cm in the warp direction and 74 kgf / 5 cm in the weft direction, and the peel strength of the folded portion 3 was 3.5 kgf.

Evaluation The marker sheet 1 of the embodiment was actually buried in the ground.
When excavated with a power shovel, the folded part is easily extended and pulled out to the ground surface without cutting, and the display characters on the printed surface are in a state that can be fully recognized without corrosion, and as a sign It was confirmed that it worked well.

[0028]

According to the marker sheet of the present invention, the use of composite flat yarns in the construction of the base fabric layer makes it easy to seal by heat treatment, and this base fabric layer has a relatively smooth surface. Since there is no bend, thread float, or thread fraying,
Display characters can be printed directly on the surface of the base fabric, and the display characters are beautiful because the printing ink does not enter between the yarns. Workability is improved. In addition, since the printed base cloth layer and the substantially two-layer structure in which the surface is covered with a protective layer, the manufacturing process can be simplified, the yield of raw materials can be improved, and the production can be performed at low cost. Becomes effective.

[Brief description of the drawings]

FIG. 1 is a partially enlarged cross-sectional view showing a laminate sheet used for a sign sheet of the present invention, in which (a) shows a base fabric layer, (b) shows a printing surface on a base fabric layer, and (c) shows a protective layer. Shows a laminated sheet having two layers.

FIG. 2 is an enlarged sectional view showing a composite flat yarn used for the sign sheet of the present invention.

FIG. 3 is a perspective view showing an example of the form of the sign sheet of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Marking sheet 2 Laminate sheet 3 Folding part 4 Folding fixing part 5 Base fabric layer 6 Printing surface 7 Protective layer 8 Composite flat yarn

Claims (1)

[Claims] 1. A composite flat yarn comprising a first polyolefin-based resin as a core layer and an outer layer formed on both surfaces thereof with a second polyolefin-based resin having a lower melting point or softening point than that of the first polyolefin-based resin, A base fabric layer in which the weft intersection is fused by heat treatment after weaving using one of the weft strips, and a protective layer that covers the printing surface on which the desired display characters have been printed with regular characters directly on the surface of the base fabric layer. Characterized in that the laminated sheet is formed with a folded portion which is folded at intervals in the longitudinal direction.