PROCESS AND DEVICE FOR SPLITTING A TAPE

Abstract

A process and a splitter for splitting a tape of a uniaxially oriented material. The tape is passed in a process direction over a splitting profile having a row of parallel teeth with a cutting edge extending in the process direction. The tape is split to form a tape comprising a plurality of parallel strips interconnected by fibrils. The split tape can for example be used for the production of high tensile ropes.

Claims

1. A process of splitting a tape of a uniaxially oriented material into a plurality of strips interconnected by fibrils, wherein the tape is passed in a process direction over a splitting profile having a row of parallel teeth with a cutting edge extending in the process direction.

2. The process of claim 1, wherein the teeth are triangular in cross section perpendicular to the process direction.

3. The process of claim 1, wherein the splitting profile is static.

4. The process of claim 3, wherein the cutting edges of each of the teeth define a circle or circular segment, the teeth being coaxially arranged.

5. The process of claim 1, wherein the distance between the cutting teeth is 0.5-5 mm.

6. The process of claim 1, wherein the tape passes the splitting profile with a processing speed of at least 1 m/min.

7. The process of claim 1, wherein the tape is fed to the splitting profile with an entrance angle of 0-90 degrees to the horizontal.

8. The process of claim 1 wherein the tape is fed to the splitting profile with an exit angle of 0-90 degrees to the horizontal

9. The process of claim 1, wherein the uniaxially oriented material is polyethylene.

10. The process of claim 1, wherein the strips are subsequently twisted to form a rope.

11. A process for the production of a rope comprising the process of splitting a tape according to claim 1, wherein a tape of a uniaxially oriented material is split into a plurality of strips interconnected by fibrils, and wherein the strips are subsequently twisted to form the rope.

12. A tape of a uniaxially oriented material comprising a plurality of parallel strips interconnected by fibrils.

13. A laminate comprising a foil layer and a layer at at least one side of the foil layer, wherein the layer is formed by laminating at least one tape according to claim 12.

14. A rope comprising one or more twisted tapes according to claim 12.

15. A splitter for splitting tapes of a uniaxially oriented material, the splitter comprising a splitter profile, a tape feeder for feeding tape to the splitter profile in a process direction, the splitter profile having a row of parallel teeth which are triangular when viewed in the process direction.

16. The splitter of claim 15, comprising a counterprofile, wherein the splitter profile and the counterprofile form a nip for passage of the tapes, the counterprofile having cutting teeth intermeshing with the teeth of the splitter profile.

Description

[0033] The invention is further explained with reference to the accompanying drawings.

[0034] FIG. 1: shows in front view an exemplary embodiment of a splitting unit;

[0035] FIG. 2: shows the splitting unit of FIG. 1 in top view during a splitting process;

[0036] FIG. 3: shows in top view a laminate comprising processed tape material;

[0037] FIG. 4: shows the laminate in side view.

[0038] FIG. 1 shows a splitter 1 for splitting UHMWPE tapes, or tapes of a similar high tensile material, to form strips for twisting a high tensile rope. The splitter 1 comprises a profile 3 and a counterprofile 5. The profile 3 and the counterprofile 5 are parallel and have teeth 6 with cutting edges 7. The teeth 6 are triangular when viewed in a direction perpendicular to a longitudinal axis X of the profile 3. The cutting edges 7 of the counterprofile 5 intermesh with those of the profile 3 to form a zig-zag nip 10 for passage of the tapes. The tapes pass the nip 10 in a process direction A perpendicular to the plane of the drawing in FIG. 1 (see FIG. 2).

[0039] In the shown embodiment the profile 3 and the counter profile 5 are two parallel mainly cylindrical bodies. However, the profile and counterprofile may have any other suitable shapes, provided that they define a zig-zag nip between intermeshing triangular cutting edges.

[0040] FIG. 2 shows in top view how a tape 12 is guided via the splitter 1. The cutting teeth 6 of the profile 3 and the counterprofile 5 split the tape 12 into a plurality of strips 13. These strips 13 are not completely separated but are still interconnected by individual fibrils 14, as is shown in FIG. 3.

[0041] The tapes 12 can for example be used in a laminate 15, as is shown in FIGS. 3 and 4. The laminate 15 comprises a foil layer 16 and layer 17 formed by the tape 12. The tape 12 is spread to increase the distance between the individual strips 13 of the tape 12. The foil carrier may for instance be an LDPE or HDPE layer. The tape can be laminated at a temperature just above the melting temperature of the foil carrier but below the melting temperature of the tape material. The laminate can have more layers formed by one or more tapes, e.g. between the enforced layer and the foil and/or on top of the foil and/or on top of the tape-reinforced layer. Such laminates have a high impact resistance.

EXAMPLE 1

[0042] Five cords were made of tapes of a UHMWPE (Endumax TA23, available from Teijin, the Netherlands). The tape width was 133 mm and the linear density was 62000 dtex. The tapes had been split in accordance with the invention with a pitch of 2 mm. The breaking force was measured using a test method in accordance with ASTM D7269 using a gauge length of 500 mm and a test speed of 150 mm/min. The used clamp type was Musschel 100 kN. The average breaking force was BF=10.44 kN.

[0043] The test was repeated under the same conditions using cords with identical tapes which had not been split. These cords had a breaking strength of 8.98 kN, which is more than 16% less than the strength of the cords according to the invention.

EXAMPLE 2

[0044] Cords were made of 20 mm tapes of UHMWPE (Endumax TA23) with twist factor 30. In a first group the 20 mm tapes had been split in accordance with the invention, using a 2 mm pitch. In a second group the 20 mm tapes had been split in accordance with the invention, using a 2.5 mm pitch. In a third group the cords were made of 10 unsplit 2 mm tapes. These tapes of the third group were not according to the invention and were not interconnected by fibrils.

[0045] The breaking strength and the breaking tenacity were tested in accordance with ASTM D7269.

[0046] Table 1 shows the breaking strength and the breaking tenacity of the tested cords.

TABLE-US-00001 TABLE 1 Cords of Cords of Cords of split tapes split tapes unsplit tapes (2 mm) (2.5 mm) (Greige) Linear density 9760 dtex 9730 dtex 9018 dtex Breaking 1680 N 1720 N 1470 N strength Breaking 1720 mN/tex 1770 mN/tex 1630 mN/tex tenacity

EXAMPLE 3

[0047] Cords were made of 20 mm tapes of UHMWPE (Endumax TA23) with twist factor 45. In a first group the 20 mm tapes had been split in accordance with the invention, using a 2 mm pitch. In a second group the 20 mm tapes had been split in accordance with the invention, using a 2.5 mm pitch. In a third group the cords were made of 10 unsplit 2 mm tapes. These tapes were not according to the invention and were not interconnected by fibrils.

[0048] The breaking strength and the breaking tenacity were tested in accordance with ASTM D7269.

[0049] Table 2 shows the breaking strength and the breaking tenacity of the tested cords.

TABLE-US-00002 TABLE 2 Cords of Cords of Cords of split tapes split tapes unsplit tapes (2 mm) (2.5 mm) (Greige) Linear density 9850 dtex 9820 dtex 9056 dtex Breaking 1610 N 1640 N 1350 N strength Breaking 1640 mN/tex 1680 mN/tex 1500 mN/tex tenacity

EXAMPLE 4

[0050] Cords were made of 20 mm tapes of UHMWPE (Endumax TA23) with twist factor 60. In a first group the 20 mm tapes had been split in accordance with the invention, using a 2 mm pitch. In a second group the 20 mm tapes had been split in accordance with the invention, using a 2.5 mm pitch. In a third group the cords were made of 10 unsplit 2 mm tapes. These narrow tapes were not according to the invention and were not interconnected by fibrils.

[0051] The breaking strength and the breaking tenacity were tested in accordance with ASTM D7269.

[0052] Table 3 shows the breaking strength and the breaking tenacity of the tested cords.

TABLE-US-00003 TABLE 3 Cords of Cords of Cords of split tapes split tapes unsplit tapes (2 mm) (2.5 mm) (Greige) Linear density 9940 dtex 9920 dtex 9154 dtex Breaking 1410 N 1330 N 1070 N strength Breaking 1420 mN/tex 1340 mN/tex 1170 mN/tex tenacity