CN85103383A

CN85103383A - Signal-transmitting cable

Info

Publication number: CN85103383A
Application number: CN198585103383A
Authority: CN
Inventors: 格鲁坦
Original assignee: NKF GELEN CO
Current assignee: NKF GELEN CO
Priority date: 1985-05-13
Filing date: 1985-05-13
Publication date: 1986-12-10

Abstract

This is a kind of airtight, waterproof, signal-transmitting cable that mechanical performance is high.It is made up of the cable core metal tape cable skin outer with being wrapped in cable core.Cable skin minimum thickness is 100 μ m; There is layer of polyethylene to adhere on the metal tape, one deck polyamide-11 or-12 are arranged on this polyethylene layer.

Description

Signal transmission cable

The invention relates to a cable provided with a core of an optical or electrical conductor surrounded by a gas-impermeable and water-impermeable cable sheath consisting of a metal foil wrapped in a lap joint. The metal foil is coated with a synthetic resin at least on its outer layer isolated from the cable core.

Metal foils coated with synthetic resin, particularly aluminum foils, are commonly used in signal transmission cables. The metal foil functions as an electrical shield. The metal layer is thin and may be, for example, 10 μm. One or both sides of the metal foil are provided with a synthetic resin layer adhered to the metal and having a thickness similar to that of the metal layer.

The use of such aluminium foil in communication cables is taught, for example, in british patent specifications 1,413,924.

According to the british patent specification, an aluminum foil with synthetic resin layers on both sides can be used as a ground shield (electrostatic shield) for four insulated electrical conductors. Micropores are left in the outer layer of the synthetic resin. According to the british patent, the multiple strands are combined to form a telephone cable, the ground shield of all the strands having a satisfactory electrical contact, this property being the presence of the remaining micro-holes. According to the british patent specification, the single-strand cable is not ideal in terms of mechanical rigidity and strength when used alone as a signal transmission cable. A layer of armour is therefore also used but this is not explicitly described in the above-mentioned british patent.

The object of the present invention is to provide a signal transmission cable with high mechanical strength which is resistant to water, such as moisture, to various chemicals, in particular to oils and organic solutions, and which is moreover robust and resistant to wear. According to the invention, such a cable can be used in a single strand, for example, it can be buried in the earth without damage and can be placed underground for many years without losing its quality. The cable also has a degree of flexibility to allow for the winding operations necessary for storage and transport. Such cables are not subject to attack by insects such as termites.

In the signal transmission cable, a lead sheath structure has been used conventionally. A known lead sheath construction cable is shown in figure 1. The use of lead-sheathed cables is, unless very expensive, also very heavy. The lead sheath is extruded at high temperature. In order to protect the cable core, a polyvinyl chloride heat insulation layer with corresponding thickness is arranged between the cable core and the lead sheath. Lead is low in strength and therefore thick. In order to strengthen, a metal protective layer is added outside the lead sheath. All this means that the diameter of the lead-sheathed cable is large. The cable provided by the invention provides a good substitute for a lead sheath cable, and has the greatest advantages of light weight, small diameter, simple production process and low price.

The object described in the article of the preceding paragraph is achieved in the manufacture of a cable of the kind mentioned in the opening paragraph. It is characterized by that it uses an aluminium or steel metal band whose band edges are overlapped, and the minimum thickness of said band is 100 micrometers, and the external layer of said metal band is covered with a synthetic resin layer containing polyethylene adhesive layer, and the polyethylene layer also contains a polyamide-11 or-12 layer.

The metal strip is preferably aluminum and has a thickness of 100-300 μm. The overlapping edges of the metal strips may be bonded by adhesive, and the edges are preferably heat welded. In this case, the adhesive layer is composed of a synthetic resin layer attached to the metal tape. Synthetic resins glued to metal strips are well known. The polyethylene is preferably a copolymer, at least a strongly polar synthetic resin, for example an acrylate having good adhesion to metal surfaces. The metal tape may be provided with a synthetic resin layer on one or both sides.

The polyethylene layer is most important to adhere to the synthetic resin skin of the metal tape. Polyethylene has good adhesion and fusion strength to the polyethylene-polyacrylate sheath.

For example, the polyethylene may be high density polyethylene which does not swell in oil, and may further contain a flame retardant. Such high density polyethylene is also a well known product. The flame retardant species is bromide Sb₂O₃And so on. The polyethylene isformed by adopting an extrusion process. Layer thicknessIt is not limited to a narrow range, such as from 0.5 to 2 mm. The polyamide-11 or-12 layer is also extruded. It is also noted here that the thickness of the layers is not essential, for example suitable layer thicknesses may be from 0.3 to 1mm, for example 0.5 mm.

The advantage of using polyamide-12 is that it has a very good meltability range, about 170 ℃ and 180 ℃, and a very low absorption. For example, at a humidity of 65%, the water absorption is 1%. As is well known, polyamides consist of the following structure:

the signal transmission cable has higher quality requirement, and reinforcing wires or belts coated with common synthetic resin can be additionally arranged around the polyamide-11 or-12 according to the invention. Such wires or ribbons may be steel. The sheath may be made of PVC, but is preferably high density polyethylene.

Generally, the use of reinforcing filaments or tapes is not necessary. In special applications, such as where a large force is applied in the transverse direction of the cable, the cable requires reinforcing filaments or tapes.

According to the invention, the signal transmission cable core may be an optical or electrical conductor. The optical conductor is a glass fibre wrapped with a layer of synthetic resin called the original coating. For this example, each glass fiber may also have a hose made of a thin synthetic resin, referred to as a secondary coating. The electrical conductors, for example steel wires, may be insulated by synthetic resin. The cable core made of optical conductor may have an inner layer of synthetic resin, which is tightly wrapped around the conductor.

In view of the quality of the cable,according to the invention one or more layers of synthetic resin foil wrapped around the cable core should also be placed between the cable core and the metal tape. Suitable foils are for example polyester foils.

The invention is described in detail below by way of illustration.

Fig. 1 is a cross-section of a conventional lead sheath cable.

Fig. 2 is a cross-section of the cable according to the invention.

Fig. 3 is a cross-section of a cable equipped with reinforcing filaments according to the invention.

Parameter 1 in fig. 1 shows a cable core consisting of 24 pairs of copper insulated wires twisted together, this point being not indicated, the cable core diameter being 16.5mm, the polyester foil ② having a thickness of 0.023mm, the aluminium foil ③ being coated on one side with a synthetic resin and having a thickness of 0.024mm, wrapped around the cable core, a further layer of polyester foil ④ having a thickness of 0.023mm, wrapped around the cable core, the polyester foil ④ having a layer of extruded polyvinyl chloride ⑤, the layer ⑤ being wrapped with an extruded aluminium skin ⑥ having a thickness of 1.35mm, itself having a polyvinyl chloride shield layer ⑦ having a thickness of 1.6mm, an armor ⑧ consisting of zinc sheet steel wires around the shield layer ⑦, the steel wires having a diameter of 1.6mm, the outer layer of the cable being protected by a layer of polyvinyl chloride ③ 0, the thickness being 2.1mm, the cable diameter shown in fig. 1 being 34.1mm, having a weight of every 2700 kg, the cable shown in fig. 1 having very good physical properties, in particular a good tensile strength, and a considerable moisture resistance, and being expensive to produce.

Fig. 2 shows a cable according to the invention, in which the cable core indicated by reference numeral 10 is the same as in fig. 1, so that the cable core diameter is also 16.5 mm. The cable core is surrounded by 2 polyester layers (11) and (12) with the same thickness of 0.023 mm. Instead of the polyester foil directly surrounding the cable core, an aluminum foil coated with a synthetic resin as an outer layer was used to surround the cable core, and the foil was used as a ground shield, and the total thickness was 0.024 mm. If desired, a ground wire, for example a steel wire, may be provided between the foil and the core. This makes it possible to achieve that the electrical shielding effect is maintained in the event of damage, for example cracks in the foil. The ground wire may also be used for ground connection. An aluminum tape (13) is wrapped around and overlapped with the polyester foil (12). The strip has a width of 60mm, a thickness of 0.23mm, an overlap of 5mm and is coated on both sides with ethylene, polyacrylate, which is not shown. The polyacrylates are each approximately 0.05mm thick. And the overlapped edges are welded together by heat. A layer of high density polyethylene (14) with flame retardant is pressed outside the aluminum strip (13). The polyethylene layer is fused with the outer protective layer of the aluminum strip, so that the layer (14) is bonded with the aluminum strip (13). The thickness of the layer (14) is 1.2 mm. Finally, a polyamide-12 layer (15) was laminated on the layer (14), the layer 15 having a thickness of 0.5 mm. The overall diameter of the cable shown in figure 2 is 20.6 mm.

The cable shown in figure 3 differs from that shown in figure 2 in that it is covered with a layer of zinc sheet wire having a diameter of 1.0mm and additionally covered with an outer layer (17) of polyethylene or polyvinyl chloride. The thickness of the outer layeris 1.9 mm. The other components of the cable shown in fig. 3 are the same as the parameters used in fig. 2.

The cables shown in fig. 2 and 3 have very good mechanical properties, for example the tensile strength of the cable shown in fig. 3 can reach 7000N, the minimum bending of which is 20 times the outer diameter of the cable and the weight of which is 1.075 kg per kilometer.

Both cables (fig. 2, fig. 3) are hermetically sealed, moisture-proof, oil-resistant, corrosive agents such as: toluene, benzene, xylene, and chemicals such as various acids and bases.

Error meter

Claims

1. A signal transmission cable having an optical or electrical conductor core surrounded by a gas-impermeable, water-impermeable cable jacket. The cable sheath is composed of metal foils which are overlapped with each other. At least one layer of synthetic resin is adhered to the metal on the outer layer of the cable sheath isolated from the cable core. Characterized in that metal strips which are overlapped with each other are made of aluminum or steel; the metal strip has a minimum thickness of 100 μm. And the synthetic resin layer attached to the metal strip has a polyethylene adhesive layer covered with a polyamide-11 or-12.

2. The signal transmission cable of claim 1 wherein the polyethylene is high density polyethylene doped with a flame retardant.

3. The signal transmission cable according to claim 1, wherein the polyamide-11 or-12 layer is coated with reinforcingfilaments or tapes of a conventional synthetic resin sheath.

4. A signal transmission cable according to any preceding claim further characterised in that one or more layers of synthetic resin are provided around the core between the core and the surrounding metal tape.