JPH0699877B2 - Cable for hanging structure - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cable for suspension structure composed of parallel wire strands used for constructing a cable-stayed bridge or a suspension structure.

(Prior art and problems to be solved) Parallel wire strands made by twisting a large number of galvanized steel strands have high strength and high elastic modulus, so they are used as cables for suspension structures of long suspension bridges. Has been adopted.

Here, the parallel wire strand refers to a steel wire bundled in parallel, or a plurality of steel wire bundles that are bundled in parallel and then twisted to such an extent that strength is not reduced. Recently, as cables for cable-stayed bridges, cables having a high-density polyethylene anti-corrosion layer, which have better corrosion resistance and are easy to handle or erection locally, have come to be used.

FIG. 3 is a cross-sectional view of an example of a conventional cable for suspension structure having an anticorrosion layer. In the drawings, (1) is a parallel wire strand formed by twisting a large number of galvanized steel strands (11), (2) is a pine tape such as filament tape, and (3) is high-density polyethylene. Is an anticorrosion layer provided by extrusion coating.

As described above, as the anticorrosion layer (3) of the parallel wire strand (1), high density polyethylene having low water permeability and high mechanical strength has been mainly used. However. In order to obtain weather resistance of 30 to 50 years, it is necessary to use black polyethylene in which 1 to 2% of carbon black is mixed in polyethylene, and it cannot be used except for black because of poor weather resistance. Therefore, in consideration of the surrounding landscape and environment, there is a problem that even if a request for coloring other than black, such as white, red, and blue, cannot be handled.

(Means for Solving the Problems) The present invention provides a cable for a suspended structure that solves the above-mentioned problems, and is characterized in that a thermoplastic fluorine-based resin is further provided on the anticorrosion layer provided on the parallel wire strands. There is provided a colored layer formed by extrusion-coating a colored polymer.

FIG. 1 is a cross-sectional view of a specific example of the cable for a hanging structure of the present invention. In the drawings, the same symbols as those in FIG. 3 represent the same parts.

In the cable for a hanging structure of the present invention, the high-density polyethylene anticorrosion layer (3) of the conventional anticorrosion cable shown in FIG.
The colored layer (4) is provided on the outer periphery of the. The colored layer (4) is formed by extrusion-coating a thermoplastic fluoropolymer such as polyvinylidene fluoride (PVDF) of a thermoplastic copolymer type to a thickness of 0.5 mm or more.

FIG. 2 is a cross-sectional view of another example of the cable for suspension structure according to the present invention. In the drawings, the same symbols as those in FIG. 1 represent the same parts.

In this example, as shown in FIG. 1, the anticorrosion layer (4) was not directly provided on the anticorrosion layer (3) made of black high-density polyethylene, and the coloring layer (4) made of a thermoplastic fluoropolymer coloring polymer was not provided. An adhesive layer (5) is applied on (3), and a colored layer (4) is provided via the adhesive layer (5).
By extruding and coating the colored layer (4) on the anticorrosion layer (3) via the adhesive layer (5), the lower anticorrosion layer (3) and the fluorine-based colored polymer of the colored layer (4) adhere to each other. However, the frictional force between the two layers can be significantly improved.
For example, when a heat-sealing layer of an ionomer range tape or sheet is applied on the anticorrosion layer (3) and the colored layer (4) is extrusion-coated, the heat at the time of extrusion coating causes the excellent heat-sealing property of the ionomer range. An adhesive (5) can be formed.

(Function) As a coloring coating material, it is considered that a coloring agent is mixed with a polyvinyl chloride composition or a polyethylene composition which is usually used and a coloring agent is extrusion-coated. It cannot be used for building a suspended structure that requires a very long service life of 30 to 50 years or more like a bridge.

That is, in the polyethylene composition, unless carbon black is added as described above, the characteristics of the polyethylene composition deteriorate in a short period of time and the composition cannot be used. Further, the polyvinyl chloride composition has been used as a coating material for electric wires and cables used outdoors, but it also has a useful life of about 10 to 20 years as a colored coating. Moreover, polyvinyl chloride has poor cold resistance and is not suitable for use in cold regions, and cannot be used as a colored coating for cables for suspension structures.

As a result of repeated studies on the colored coating material, the inventors of the present application have found that a coating of a thermoplastic fluorine-based polymer having excellent weather resistance and excellent general physical properties such as cold resistance and strength is suitable. I found it.

In particular, when polyethylene is used as the anticorrosion layer, when PVDF copolymer is used as the thermoplastic fluoropolymer, the temperature at the time of PVDF extrusion is relatively low at about 200 tens of degrees Celsius, so there is almost no heat effect on polyethylene and it is even better.

As the covering means, extrusion covering, tape-shaped processing and winding, or tube-shaped material having heat-shrinkability inserted from the end and heat-shrinking can be considered.

When winding a long parallel wire strand around a reel, the end of the tape floats up, causing a misalignment, or winding it in a straight line to completely return it to its original state. There are problems such as wrinkles that do not return and tend to occur. Further, the method of inserting the heat-shrinkable tube from the end and shrinking it is not practical because the length of the tube is limited or there is a problem in working to insert more than several tens of meters.

For these reasons, extrusion coating of the thermoplastic fluoropolymer is inevitable, the actual work is easy, the obtained cable has good weather resistance, and the aesthetic problem is solved. By the way,
In the polyvinyl chloride coloring material, deterioration was observed at 2000H in the test by the sunshine weatherometer, but PVDF, ETF
The colorants of the fluoropolymers of E and FEP showed almost no change even after 5000 hours, and were sufficiently durable to use.

Next, the cable for suspension structure shown in FIG. 1 has a structure in which the coloring layer of the fluorine-based coloring polymer is directly extrusion-coated on the anticorrosion layer of the high-density polyethylene, so that the friction between the lower polyethylene layer and the fluorine-containing coloring polymer is reduced. If the cable has a large resistance and its resistance is small and the middle part is gripped during construction to lift the cable for a suspended structure, the colored layer, which is relatively thin compared to the anticorrosion layer, may slip and damage the surface of the anticorrosion layer. Therefore, it is necessary to cover it with a thickness more than necessary (in this case, it is also disadvantageous in terms of cost), or to improve the construction method, for example, to make the cable grip longer than before. A case arises.

On the other hand, in the specific example shown in FIG. 2, since the coloring layer is provided on the high-density polyethylene anticorrosion layer via the adhesive layer, the lower anticorrosion layer and the coloring layer adhere to each other, The frictional force between the layers is remarkably improved, and the problem of concern in the cable for suspension structure of FIG. 1 can be solved.

(Example) (1) A black high density in which a filament tape as a binder is wound to a thickness of about 1 mm on a parallel wire strand formed by twisting 7 mmφ × 85 pieces of galvanized steel wire, and carbon black is mixed on it. A cable for suspension structure having an anticorrosion layer formed by extrusion-coating polyethylene and further having the colored layer shown in Table 1 formed thereon was manufactured and evaluated. The results are shown in Table 1.

(2) Color tone evaluation: To examine the thickness required for the colored layer,
PVDF sheets with thicknesses of 0.2 mm, 0.5 mm and 1 mm are white,
Three colors, red and blue, were prepared and wound on a black high-density polyethylene anticorrosion layer for checking. It was found that the following thicknesses or more were required for each color, as a thickness that was hardly affected by the color of the base.

White 0.5 mm Red 0.2 mm Blue 0.5 mm (3) Regarding the surface hardness of the colored layer, the hardness of the high-density polyethylene, which is usually the lower layer, is about Shore (D) 60,
If the hardness is smaller than this and it is soft, it is likely to be scratched, and it is necessary to be harder than this. However, if it is too hard, there is a problem that the surface colored layer floats up when bent and becomes wrinkled, or when an external force is applied, the inner anticorrosion layer is deformed. ) 60-80 is desirable.

(4) The total thickness of the colored layer must be 0.5 mm or more in terms of color tone and scratch resistance. On the other hand, in actuality, it is not necessary to coat the layer thicker than necessary from the viewpoint of cost, and when the lower diameter for coating the colored layer is dmm (d ≧ 20) and the thickness of the colored layer is tmm, t / d ≦ 0.05 The following is desirable.

(5) Wrap a filament tape as a binder to a thickness of about 1 mm on a parallel wire strand made by twisting 7 mmφ × 139 pieces of galvanized steel wire, and wrap black high density polyethylene mixed with carbon black on it. 9.0 mm
An anticorrosion layer extruded and coated with a thickness was provided to obtain an anticorrosion cable having an outer diameter of about 113 mm.

Approximately 50 μm-thick high-milan tape (trade name, manufactured by Mitsui Polychemical Co., Ltd.) is applied as a heat-sealing layer on the anticorrosion layer.
It was wound in a 1/4 wrap, and polyvinylidene fluoride (PVDF) was extrusion-coated thereon as a colored layer to obtain a cable for suspension structure as shown in FIG.

Table 2 shows the evaluation results of the obtained cable and the cable having no heat-sealing layer as shown in FIG.

In this embodiment, when the colored layer is extrusion-coated, heating the cable wound with the high-milan tape with a heater or hot air before the extruder further improves the adhesion. The high-milan tape is not limited to the tape winding, but may be open-winding or may be vertically attached in the length direction and the side edges are overlapped to obtain the same effect. To be Further, the heat-sealing layer may be a base material such as polyethylene, polypropylene, or polyester with high-milan tape stuck on both sides, or if the diameter is relatively small, it may be applied by extrusion coating. May be.

(Effects of the Invention) As described above, according to the colored cable for a hanging structure of the present invention, since it can be colored in various colors, it is excellent in aesthetics and can be harmonized with the surrounding environment. When used as a cable for suspension structures such as cable-stayed bridges and domes,
It is extremely effective.

Further, by interposing an adhesive layer between the anticorrosive layer and the colored layer, the adhesion between the two layers is remarkably improved, and the colored layer is prevented from being damaged during construction. As a result, it is possible to reduce the thickness of the colored layer made of a fluoropolymer, which is an expensive material, and it can be expected to realize a cable for a suspended structure at low cost.

[Brief description of drawings]

1 and 2 are transverse cross-sectional views of specific examples of the cable for a hanging structure according to the present invention. FIG. 3 is a cross-sectional view showing an example of a conventional cable for suspension structure. 1 ... PWS, 2 ... binder tape, 3 ... anticorrosion layer, 4 ... coloring layer, 5 ... adhesive layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadashi Fujiwara 1-3-3 Shimaya, Konohana-ku, Osaka City, Osaka Prefecture Sumitomo Electric Industries, Ltd. Osaka Works (72) Inventor Tetsuo Hojo 5 Nishihashimoto, Sagamihara City, Kanagawa Prefecture 9-1 No. 1 Nippon Steel & Steel Co., Ltd. Steel Construction & Marine Division (72) Inventor Isamu Tsuchida 5-9-1, Nishihashimoto, Sagamihara-shi, Kanagawa Nippon Steel & Co., Ltd. Steel Construction & Ocean Division (56) References JP 60-13102 (JP, A) Actually open 1-11-1293 (JP, U) Actually open 60-136396 (JP, U)

Claims (3)

[Claims] 1. A cable for a suspended structure, characterized in that a colored layer formed by extrusion-coating a thermoplastic fluoropolymer is further provided on the anticorrosion layer provided on the parallel wire strands. 2. The cable for a suspended structure according to claim 1, wherein a colored layer is provided on the anticorrosion layer provided on the parallel wire strand via an adhesive layer. 3. The surface hardness of the colored layer is Shore hardness (D) 60.
The cable for a suspended structure according to claim 1 or 2, wherein the cable has a thickness of -80 and a thickness of 0.5 mm or more.