STEEL WIRE NETTING WITH DOUBLE COATING

Abstract

A steel wire netting (100, 200) is adapted to be used in erosion control, in geotechnical solutions, in rockfall protection or in aquaculture. The steel wire netting (100, 200) comprises steel wires (300). These steel wires (300) have a steel core (302). The steel core (302) is of a low-carbon or high-carbon nature. The steel wires (300) further have an intermediate metallic coating (306) of zinc or an zinc aluminium alloy or a zinc aluminium magnesium alloy on the steel core (302). The steel wires (300) further have a top coating of a polymer (310). This polymer (310) is a high density polyethylene.

Claims

1. A steel wire netting adapted to be used in erosion control, in geotechnical solutions, in rockfall protection or in aquaculture, said steel wire netting comprising steel wires, said steel wires having a steel core, said steel core being of a low-carbon or high-carbon nature, said steel wires further having an intermediate metallic coating of zinc or a zinc aluminium alloy or a zinc aluminium magnesium alloy on the steel core, said steel wires further having a top coating of a polymer, said polymer being a high density polyethylene.

2. The steel wire netting according to claim 1, wherein said top coating of a polymer is a single coating.

3. The steel wire netting according to claim 1, wherein an adhesion layer of modified polyolefin is present between the intermediate metallic coating and the polymer top coating.

4. The steel wire netting according to claim 1, wherein said intermediate metallic coating is a coating of zinc and unavoidable impurities.

5. The steel wire netting according to claim 4, wherein a zinc iron alloy layer is present between the steel core and the zinc coating.

6. The steel wire netting according to claim 1, wherein said intermediate metallic coating is a coating of a zinc aluminium alloy with 4 wt % to 12 wt % aluminium, the rest being zinc and unavoidable impurities.

7. The steel wire netting according to claim 1, wherein said intermediate metallic coating is a coating of a zinc aluminium alloy with 4 wt % to 12 wt % aluminium and with between 0.05% and 3% of magnesium, the rest being zinc and unavoidable impurities.

8. The wire netting according to claim 1, wherein said polymer is a high-density polyethylene of the bimodal based type with at least one co-reactant selected out of the group of butane, hexane and octane.

9. The wire netting according to claim 8, wherein copolymer of ethylene and methacrylic acid has been added to the polymer.

10. The wire netting according to claim 8, wherein said polymer is a high-density polyethylene wherein a linear low density polyethylene has been mixed.

11. The wire netting according to claim 1, wherein said wire netting is a double twist hexagonal netting.

12. The wire netting according to claim 1, wherein said wire netting is a chain link fence.

13. A gabion made out of a wire netting according to claim 1.

14. The steel wire netting according to claim 2, wherein an adhesion layer of modified polyolefin is present between the intermediate metallic coating and the polymer top coating.

15. The wire netting according to claim 9, wherein said polymer is a high-density polyethylene wherein a linear low density polyethylene has been mixed.

Description

BRIEF DESCRIPTION OF FIGURES IN THE DRAWINGS

[0030] FIG. 1 is a schematic representation of part of a double-twist hexagonal wire netting.

[0031] FIG. 2 is a schematic representation of part of a chainlink mesh.

[0032] FIG. 3 is a cross-section of a double coated steel wire according to the invention.

[0033] FIG. 4 shows preparation of a wire for an adhesion test.

MODE(S) FOR CARRYING OUT THE INVENTION

[0034] FIG. 1 is a schematic representation of part of a double-twist hexagonal wire netting 100. The part that is shown on FIG. 1 has four double-coated steel wires 102, 104, 106 and 108. Each of these steel wires 102, 104, 106 and 108 makes alternatingly a connection with a neighboring steel wire at the left side and a neighboring steel wire at the right side. Each connection is formed by intertwisting the two neighboring steel wires. The intertwisting 110 shows the twisting of steel wire 102 with steel wire 104. As this intertwisting is done in a same process over the whole width of the entire wire netting, hexagonal meshes 112 are formed.

[0035] FIG. 2 is a schematic representation of part of a chainlink mesh 200. The part shown in FIG. 2 has five undulated or zigzag steel wires 202, 204, 206, 208 and 210 which are alternatingly woven with a left neighboring steel wire and a right neighboring steel wire.

[0036] FIG. 3 shows the cross-section of a double coated steel wire 300 used in the wire netting according to the invention. A steel core 302 has an intermediate metallic coating of zinc 306. A brittle zinc iron alloy forms the transition 304 between the steel and the zinc. In order to enhance the adhesion with the top coating of polymer, an adhesion layer (primer) 308 is present between the zinc layer and the top coating 310. The top coating 310 is a high-density polyethylene.

[0037] The steel wires used in the present invention can be of a low-carbon nature or of a high-carbon nature.

[0038] A low-carbon steel composition has a carbon content ranging between 0.04 wt % and 0.20 wt %. An example of a complete composition of such a low-carbon steel is as follows: a carbon content of 0.06 wt %, a silicon content of 0.166 wt %, a chromium content of 0.042 wt %, a copper content of 0.173 wt %, a manganese content of 0.382 wt %, a molybdenum content of 0.013 wt %, a nitrogen content of 0.006 wt %, a nickel content of 0.077 wt %, a phosphorus content of 0.007 wt %, a sulphur content of 0.013 wt %.

[0039] A high-carbon steel composition carbon is a steel composition having more than 0.60 wt % carbon, more particularly it is a steel composition along following lines (all percentages being percentages by weight): [0040] a carbon content (% C) ranging from 0.60 wt % to 1.20 wt %, e.g. 0.80 wt % to 1.1 wt %; [0041] a manganese content (% Mn) ranging from 0.10 wt % to 1.0 wt %, e.g. from 0.20 wt % to 0.80 wt %; [0042] a silicon content (% Si) ranging from 0.10 wt % to 1.50 wt %, e.g. from 0.15 wt % to 0.70 wt %; [0043] a sulphur content (% S) below 0.03 wt %, e.g. below 0.01 wt %; [0044] a phosporus content (% P) below 0.03 wt %, e.g. below 0.01 wt %.

[0045] As a matter of example of making a wire netting according to the invention, starting from a wire rod with the suitable composition, the wire rod is drawn until its desired final steel wire diameter.

[0046] The thus drawn steel wire is then subjected to a hot dip galvanizing process to provide a zinc coating with a zinc-iron alloy transition layer to the core steel wire.

[0047] The zinc coated steel wire is then guided through a bath filled with a suitable primer to enhance the adhesion between the metallic intermediate coating and a top polymer coating. Alternatively the primer can be sprayed on the zinc coated steel wire.

[0048] Finally the top polymer coating may be applied to the zinc coated steel wire by means of an extrusion process.

[0049] Test

[0050] The adhesion of a prior art polymer coating and various invention polymer coatings on a steel wire was tested via the so-called Furukawa adhesion test. Referring to FIG. 4, a steel wire 400 is covered with a polymer coating 402. The polymer coating 402 is removed from the steel wire except for a length of 10 mm. The steel wire 400 with the remaining coating 402 is then pulled through a calibrated opening to strip the remaining coating 402. The force needed for this stripping is recorded.

[0051] Following types of polymer coating have been tested: [0052] 1) PVC: prior art polyvinylchloride; [0053] 2) HDPE: high-density polyethylene; [0054] 3) HDPE A: high-density polyethylene of the bimodal based type with at least one co-reactant selected out of the group of butane, hexane and octane; [0055] 4) HDPE B: high-density polyethylene wherein a linear low density polyethylene has been mixed.

[0056] Test Results

TABLE-US-00001 Thickness Adhesion layer Stripping Polymer coating (μm) (Yes/No) Force (N) PVC - prior art 500 No 17 HDPE - invention 500 No 40 HDPE - invention 500 Yes 261 HDPE A - invention 500 Yes 148 HDPE B - invention 500 Yes 212

[0057] The values of the stripping force are average values of five stripping tests.