JPH0412408A - Water cut-off tape - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a water-shielding tape used for electrical cables and the like buried underground.

[Conventional technology]

In recent years, in order to preserve the aesthetic appearance of cities by eliminating utility poles on the streets, electric power cables are being buried underground at a rapid pace. However, water permeates through the sheath of power cables buried underground, causing what is called a water tree (tree-like progression of water), which causes the inside of the power cable to deteriorate. The problem is that it gets destroyed.

Therefore, conventionally, a water-blocking layer is provided inside the power cable in order to prevent water from advancing. An example of the cross section of this power cable is shown in FIG. In FIG. 5, a power cable A includes an inner semiconducting layer 2, an insulating layer 3, an outer semiconducting layer 4, a semiconducting cloth tape layer 5, and a metal shield J such as copper tape or copper wire on a conductor l. ! 6. A semiconductive cloth tape layer 7, a water-blocking layer 8, and an anticorrosion layer 9 made of polyvinyl chloride are each provided in sequence substantially coaxially. The insulator layer 3 consists of the conductor 1 and the semiconducting layers (outer semiconducting layer 4,
This layer electrically insulates the semiconductive cloth tape layer 5, the metal shielding layer 6 made of copper tape or copper wire, and the semiconductive cloth tape layer 7). The semiconducting layer is a layer that electrically protects the conductor 1, and serves, for example, to ground electricity. As the water-blocking layer 8, a water-blocking tape is used.

Water-shielding tape consists of metal foil as a water-shielding material and a plastic film (for example,
It is basically constructed by laminating polyester films).

Examples of conventional waterproof tape are shown in Figures 2, 3, and 4.
Each is shown in the figure.

In FIG. 2, the water-blocking tape 1O is made up of a plastic film 13 laminated on the surface of a metal foil 15 via an adhesive layer 14, and a sheath adhesive film layer 11 laminated on this surface via an adhesive layer 12. It is constituted by The sheath adhesive film layer 11 is provided in consideration of adhesion to the anti-corrosion layer 9 (sheath).

3 is the same as in FIG. 2 except that a conductive thermoplastic film 16 is heat-sealed to the back surface of the metal foil 15.

4 is the same as in FIG. 2 except that a conductive polyvinyl chloride film 18 is laminated on the back surface of the metal foil 15 via a conductive adhesive layer 17. In addition, the third
The reason why the thermoplastic film is made conductive in the figure and the adhesive layer and the polyvinyl chloride film are made conductive in FIG. 4 is to make the metal foil 15 electrically conductive to the semiconductive layer.

However, as shown in FIG. 2, the water-shielding tape 10 without the four-electroconductive layer on the back side of the metal foil 15 has the disadvantage that it has poor bending resistance and is susceptible to cranking in the metal foil 15 due to bending of the electrical cable. be.

In addition, as shown in FIG. 3, the water-shielding tape 10 in which a conductive thermoplastic film 16 is heat-sealed to the back surface of a metal foil 15 has excellent bending resistance, but it takes time to laminate due to heat-sealing. Therefore, productivity is poor, and since the conductive thermoplastic film 16 increases the weight, there is a problem that the load on the winding device for the water-blocking tape 10 increases. Furthermore, as shown in FIG.
Although the water shielding element 10 made by laminating the same has excellent bending resistance and productivity is higher than that of heat fusion,
Since the adhesive layer must be made thicker to provide a certain degree of adhesive strength, it is heavier than in the case of heat-sealing, and has disadvantages such as higher material costs.

[Problem to be solved by the invention]

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a water-blocking tape that is excellent in bending resistance, productivity, and lightness.

[Means to solve the problem]

The water-blocking tape of the present invention is characterized in that a plastic film is laminated on the surface of a metal foil, and a conductive coating material layer is laminated on the back surface of the metal foil.

As described above, in the present invention, since the conductive coating material layer is laminated on the back surface of the metal foil, it is excellent in terms of bending resistance, productivity, and light weight.

Hereinafter, the above means will be explained in detail with reference to the drawings. Note that the same parts as in FIGS. 2 to 4 are represented by the same numbers.

FIG. 1 is an explanatory cross-sectional view of an example of the water-blocking tape of the present invention. In FIG. 1, a plastic film 13 is laminated on the surface of a metal foil 15.

This lamination is usually done via an adhesive layer 14. Furthermore, an adhesive 1i is applied to the surface of the plastic film 13.
A sheath adhesive film layer 11 is laminated with a sheath adhesive film layer 12 interposed therebetween.

A conductive coating material layer 19 is laminated on the back surface of the metal foil 15.

As the metal foil 15, lead foil, aluminum foil, copper foil, stainless steel foil, or alloy foil containing these metals as main components can be used. If the thickness of the metal foil 15 is too thin, pinholes will easily occur, and if it is too thick, the weight of the water-blocking tape will increase and the cost will also increase.
The thickness is preferably about 100 μm. Note that since metal foil with a thickness of 5 μm or more is commercially available, this metal foil can also be used.

The plastic film 13 is, for example, a polyester film such as a polyethylene terephthalate film (PE'r film), a polyvinyl chloride film, a polyimide film, or a polycarbonate film.

The thickness is preferably about 15 to 200 μm.

The sheath adhesive film layer 11 is a layer in contact with the anticorrosion layer 9 . The anti-corrosion layer 9 is usually made of soft polyvinyl chloride. Further, the water-blocking tape 10 is flat-wound so that one side edge and the other side edge are overlapped along the longitudinal direction so that the conductive coating material layer 19 is in contact with the semi-conductive layer. When wrapped around the conductive layer, the sheath adhesive film layer 11 comes into contact with the conductive coating material layer 19 at the overlapping portion. Therefore, it is preferable that the sheath adhesive film layer 11 is capable of adhering well to both the anticorrosive layer 9 and the conductive coating material layer 19.

For this purpose, as the adhesive film layer 11 for the sheath,
It is preferable to use a thermoplastic hot melt film. This hot melt film is directly laminated to the plastic film 13 by heat fusion, or as shown in FIG. 1, it is laminated via the adhesive layer 12.

Lamination of the current conductive coating material layer 19 on the back surface of the metal foil 15 is performed by coating the back surface of the metal foil 115 with a conductive resin paint.

The conductive resin paint can be obtained by mixing and stirring a conductive material, a resin, and, if necessary, a curing agent with an organic solvent. This conductive resin coating preferably has a volume resistivity of 10'Ω·cm or less after drying or curing. As the conductive material, for example, carbon black, graphite, metal powder, a balloon or filler whose surface is coated with metal, ceramics having conductivity, etc. can be used. Further, the resin is, for example, a general reactive resin such as an epoxy resin, a urethane resin, an acrylic resin, a vinyl chloride resin, or a polyester resin, or another polymer that can be dissolved in an organic solvent.

This conductive resin paint has a viscosity (for example, 50 cps to 1000 cps) when passed through a coating device during use.
), the viscosity is adjusted with an organic solvent, and the metal foil 1 is coated with gravure coating, reverse coating, or other coating methods.
A thin coating is applied to the back side of 5.

The thickness of the conductive coating material layer 19 formed by coating the conductive resin paint after drying is 0.1 to 3
A range of 0 μm is preferable. This is because if it is too thin, the coating operation will be difficult and the bending resistance will be poor, and if it is too thick, the coating speed will be low in terms of drying and productivity will be reduced. Preferably, the thickness is 1 to 20 μm.

By reducing the thickness of the conductive coating material layer 19 in this manner, the drying speed of the organic solvent becomes faster, so that the coating speed and hence the productivity can be increased. In addition, since the weight per unit area of the resulting water-shielding tape 10 is reduced, the load on the winding device for the water-shielding tape 10 is reduced, and as a result, as shown in FIGS. 3 and 4, the conductivity is reduced. It becomes possible to obtain a long object compared to the case where a film is used.

Examples are shown below.

Examples Waterproof tapes below (invention tape, conventional tapes 1 to 3)
The productivity, light weight, and bending resistance were evaluated. The results are shown in Table 1.

Here, productivity was evaluated by line speed, and lightness was evaluated by weight per unit area. In addition, the bending resistance is JIS-
Compliant with P-8115. That is, using a paper and plastic material folding strength tester (formerly T-S type, manufactured by Toyo Seiki), a load of 500 g was applied to a test piece cut into a predetermined shape, and the test piece was tested with a tip radius of 0.8 mm. The metal foil was bent by 135 degrees left and right using a bending device, and the number of times the metal foil was broken and no longer conductive was measured.

■ Inventive tape (Figure 1).

A polyester film (thickness: 50 μm) was used as the plastic film. A polyester adhesive was applied to one side of the film so that the thickness after drying was 30 μm. After drying the organic solvent using a dryer, using a laminating roll. Then, a lead foil (thickness: 50 μm) was bonded to this coated surface as a metal foil.

Next, a polyester adhesive was applied to the bonded one-sided polyester film to a thickness of 30 μm after drying.
After drying, a true melt film (thickness: 50 μm) was attached as a sheath adhesive film layer to the coated surface using a laminating roll in the same manner, and stored at 40° C. for 3 days.

A conductive resin paint consisting of carbon black (acetylene black), graphite, flexible epoxy resin, curing agent, and organic solvent was applied to the back side of the lead foil of the tape obtained in this way to a thickness of 5 μm after drying. After coating with gravure coating and drying, it was cured at 40°C for 3 days to obtain a water-blocking tape.

At this time, the coating speed and lamination speed of the adhesive were 10 m/min, and the coating speed of the conductive resin paint was 100 m/min.

■ Conventional tape 1 (Figure 2).

A polyester film (thickness: 50 μm) was used as the plastic film. A polyester adhesive was applied to one side of the film so that the thickness after drying was 30 μm. After drying the organic solvent using a dryer, using a laminating roll. Then, lead foil (thickness: 50 μl) was bonded to this coated surface as a metal foil.

Next, a polyester adhesive was applied to the bonded polyester film on one side to a dry thickness of 30 μm.
After drying, Honmelt film (thickness 50μl11) was laminated on the coated surface as an adhesive film layer for the sheath using a laminating roll in the same way, and the film was cured at 40°C for 3 days and shielded. Got water tape.

■ Conventional tape 2 (Figure 3).

The procedure is the same as the conventional Qi 11 until the hot melt film is attached and cured at 40° C. for 3 days. Next, a conductive polyethylene thermoplastic film (thickness: 50 .mu.n+) was bonded to the back surface of the lead foil by heat fusion using a heated laminating roll to obtain a water-blocking tape.

At this time, the heat fusion bonding speed was 3 m at 150°C.
/min, and if the speed is faster than this, sufficient adhesion cannot be obtained. Furthermore, when the temperature is raised above 150'C, there is a problem in that wrinkles occur due to thermal expansion.

■ Conventional tape 3 (Figure 4).

The procedure is the same as that of conventional tape 1 until the Honmelt film is attached and cured at 40° C. for 3 days. Next, a conductive urethane adhesive was applied to the back side of the lead foil so that the thickness after drying was 30 μm, and a conductive polyvinyl chloride film (thickness: 50 μl/l) was bonded to this coated surface. Ta. It was cured at 40°C for 3 days to obtain a water-blocking tape.

At this time, the coating speed and lamination speed of the urethane adhesive were 10 m/min, and if the speed was faster than this, a problem occurred in that the organic solvent remained.

Furthermore, when the thickness of the adhesive is reduced in order to increase the drying speed, a problem arises in that the adhesive force is reduced, and it has been found that the thickness after drying is preferably at least 25 μm or more.

From Table 1, it can be seen that the tape of the present invention has a lower
It can be seen that productivity, light weight, and bending resistance are all well-balanced and excellent.

〔Effect of the invention〕

As explained above, the water-blocking tape of the present invention is excellent in all of 4° productivity, light weight, and bending resistance. Therefore, according to the present invention, it is possible to provide a water-blocking tape that is highly productive and therefore inexpensive. In addition, since it is lightweight, it is easy to handle, and the load placed on the water-blocking tape winding device is reduced.
Accordingly, it becomes possible to obtain a long piece of water-blocking tape.

Furthermore, since it has good bending resistance, it is easy to handle and has excellent water shielding reliability.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional explanatory diagram of an example of the water-blocking tape of the present invention, and FIG.
4 are cross-sectional explanatory views of an example of a conventional water-shielding tape, and FIG. 5 is a cross-sectional explanatory view of an example of an electric cable. DESCRIPTION OF SYMBOLS 1... Conductor, 2... Inner semiconducting layer, 3... Insulator layer, 4... Outer semiconducting layer, 5... Semiconducting cloth tape layer, 6... Metal shielding layer , 7... Semi-conductive cloth tape layer, 8... Water-blocking layer, 9... Anti-corrosion layer, 10... Water-blocking tape, 11... Adhesive film layer for sheath, 12...
・Adhesive layer, 13...Plastic film, 14.
... Adhesive layer, 15... Metal foil, 16... Conductive thermoplastic film, 17... Conductive adhesive layer, 18...
- Conductive polyvinyl chloride film, 19... conductive coating material layer.

Claims (1)

[Claims] A water-blocking tape made by laminating a plastic film on the surface of metal foil and laminating a conductive coating material layer on the back side of the metal foil.