STRONG AND STRETCHABLE SEAM TAPE

Abstract

The present invention relates to a seam tape comprising at least one layer of unidirectionally aligned fibers whereby the fibers are oriented substantially perpendicular to the length of the tape and the strength of the tape in the perpendicular direction is at least 200 N/ 2.54 cm [inch]. The fibers are selected from the group of UHMWPE, polyamide, polyester, glass or carbon fibers. Preferably the fibers are UHMWPE fibers. The seam tape may further comprise a hot melt adhesive. The hot melt adhesive preferably has a melting point which is at least 25° C. to 70° C. lower than the melting point of the fibers. The hot melt adhesive is chosen from the group consisting of thermoplastic polymers such as polyamides, co-polyamides, polyamino-amides, polyesters, polyacrylates, polymethacrylates, polyolefins, ethylene/vinyl acetate copolymers or mixtures thereof. The present invention further relates to the use of the seam tape in backpacks, packs, bags, medical gear, outdoor products, sail cloths, tents, tarps, shelters, clothing, ponchos, foul weather gear, mats, outerwear, jackets, sleeping bags, lift bags, parachutes, large kites, inflatable structures, beams, balloons, packraft, inflatable gear, liferaft, inflatable sculptures, airship (HAA: High Altitude Airships), space applications, flexible circuits and footwear, inflatables, radomes, tensioned structures, or umbrellas.

Claims

1. Seam tape comprising at least one layer of unidirectionally aligned fibers whereby the fibers are oriented substantial perpendicular to the length of the tape and the strength of the tape in the perpendicular direction is at least 200 N/ 2.54 cm [inch].

2. Seam tape according to claim 1 whereby the layer(s) comprise fibers selected from the group of UHMWPE, polyamide, polyester, glass or carbon fibers.

3. Seam tape according to claim 1 wherein the fibers are UHMWPE fibers.

4. Seam tape according to claim 1 wherein the thickness of the tape is between 125-500 μm.

5. Seam tape according to claim 1 further comprising a hot melt adhesive.

6. Seam tape according to claim 5 further comprising a hot melt adhesive with a melting point which is no more than 50° C. higher than the melting point of the fibers.

7. Seam tape according to claim 5 whereby the hot melt adhesive is chosen from the group consisting of thermoplastic polymers such as polyamides, copolyamides, polyaminoamides, polyurethanes, polyesters, polyacrylates, polymethacrylates, polyolefins, ethylene/vinyl acetate copolymers or mixtures thereof.

8. Seam tape according to claim 5 whereby the thickness of the hot melt adhesive layer may vary from 10 μm and 1 mm.

9. Seam tape according to claim 1 comprising a barrier film with an elastic modulus below 1 GPa.

10. Seam tape according to claim 9 in which the barrier film comprises a higher melting temperature than melting temperature of the fibers.

11. Seam tape according to claim 9 whereby the thickness of the barrier layer may vary from 10 μm and 1 mm.

12. Seam tape according to claim 9 in which the barrier film is a thermoplastic polyurethane.

13. Seam tape according to claim 1 whereby the unidirectionally aligned fibers are embedded in a matrix material.

14. Seam tape according to claim 13 whereby the matrix material is identical to the hot melt adhesive.

15. Seam tape according to claim 1 whereby the overall stiffness of the tape is less than 10,000 N/m.

16. Use of the seam tape according to claim 1 in backpacks, packs, bags, medical gear, outdoor products, sail cloths, tents, tarps, shelters, clothing, ponchos, foul weather gear, mats, outerwear, jackets, sleeping bags, lift bags, parachutes, large kites, inflatable structures, beams, balloons, packraft, inflatable gear, liferaft, inflatable sculptures, airship (HAA: High Altitude Airships), space applications, flexible circuits and footwear, inflatables, radomes, tensioned structures, or umbrellas.

Description

FIGURES

[0038] FIG. 1: a 1 cm wide seam tape with reinforcement perpendicular to tape length able to form seal over a circle with inner diameter 6.5 cm, outer diameter 8.5 cm without the formation of creases or folds in the tape

[0039] FIG. 2: a 1.5 cm wide seam tape with reinforcement perpendicular to tape length able to form seal over a circle with inner diameter of 6 cm, outer diameter 9 cm without the formation of creases or folds in the tape.

[0040] FIG. 3: a 2 cm wide seam tape with reinforcement perpendicular to tape length able to form seal over a circle with inner diameter of 5.5 cm, outer diameter 9.5 cm without the formation of creases or folds in the tape

METHODS OF MEASURING

[0041] 1.Side chains in a polyethylene or UHMWPE sample is determined by FTIR on a 2 mm thick compression molded film by quantifying the absorption at 1375 cm.sup.−1 using a calibration curve based on NMR measurements (as disclosed in e.g. EP 0 269 151)

[0042] 2.Tensile properties, i.e. strength and modulus, of fibers were determined on multifilaments as specified in ASTM D885M, using a nominal gauge length of the fibre of 500 mm, a crosshead speed of 50%/min and Instron 2714 clamps, of type Fibre Grip D5618C. For calculation of the strength, the tensile forces measured are divided by the titre, as determined by weighing 10 meter of fibre; values in GPa for are calculated assuming the natural density of the polymer, e.g. for UHMWPE is 0.97 g/cm.sup.3.

[0043] 3.The tensile properties of tapes: tensile strength, tensile modulus, and elongation at break are defined and determined at 20° C. on tapes (if applicable obtained by slitting) of a width of 2 mm as specified in ASTM D882, using a nominal gauge length of the tape of 131 mm, a crosshead speed of 50 mm/min.

EXAMPLES

Example 1

[0044] Seam tapes were constructed with UHMWPE fibers that were oriented perpendicular to the tape length.

[0045] The seam tape comprises an outer barrier layer which is an elastomeric thermoplastic polyurethane, an adhesive layer which is a hot melt thermoplastic polyurethane, a fiber layer that consists of UHMWPE fibers embedded in a polymer matrix and a final adhesive layer which is a hot melt thermoplastic polyurethane. The seam tape was slit to different widths and the smallest radius of curvature circle it was able to seal without the formation of creases or folds. Samples were adhered using a hot press at temperatures below 140° C. to a composite fabric with a thermoplastic polyurethane face film. Results are given in Table 1

COMPARATIVE EXPERIMENT A

[0046] Seam tapes were constructed as in example 1 except that the UHMWPE fibers were either orientated parallel and perpendicular to the tape length. Results are given in Table 1.

RESULTS

[0047]

TABLE-US-00001 TABLE 1 Water column Tape Inner Folds or height when Exam- Width diameter Creases leakage is ple Tape [cm] [cm] observed? observed 1.1 Example 1 1 6.5 No >500 cm H20  A.1 Compara- 1 6.5 YES 40 cm H20 tive Ex A A.2 Compara- 1 16 Yes Not measured tive Ex A 1.2 Example 1 2.5 9 No Not measured A.3 Compara- 2.5 9 YES Not measured tive Ex A 1.3 Example 1 1.5 6 No Not measured 1.4 Example 1 2 5.5 No Not measured

[0048] From the results in Table 1 it is clear that Example 1, with fibers are oriented perpendicular to the tape length can form a crease free seal at much smaller radius of curvature than the tape of comparative experiment A with the same total amount of fiber reinforcement but with fibers orientated both parallel and perpendicular to the tape length.