PROCESS FOR THE PRODUCTION OF A MONOLAYER COMPOSITE ARTICLE, THE MONOLAYER COMPOSITE ARTICLE AND A BALLISTIC-RESISTANT ARTICLE

Abstract

Process for the production of a monolayer composite article comprising an unidirectional array of high performance polyolefin fibers, the process comprising the steps of positioning of the fibers in a coplanar, parallel fashion consolidation of the fibers to obtain the monolayer composite article,
the process comprises after the step of position of the fibers and before or after the step of consolidation of the fibers, a step in which the fibers are stretched.

Claims

1. Process for the production of a monolayer composite article comprising an unidirectional array of high performance polyolefin fibers, the process comprising the steps of (a) positioning of the fibers in a coplanar, parallel fashion (b) consolidation of the fibers to obtain the monolayer composite article, wherein the process comprises after the step (a) of positioning of the fibers and before or after the step (b) of consolidation of the fibers, a step in which the fibers are stretched.

2. Process for the production of a monolayer composite article according to claim 1, wherein a plastic matrix material is used for the consolidation.

3. Process for the production of a monolayer composite article according to claim 2, wherein the fibers are consolidated by embedding the fibers partially or wholly in a plastic matrix material.

4. Process for the production of a monolayer composite article according to claim 1, wherein the stretching of the fibers takes place by increasing the transport velocity of the fibers at a position in the process line for the production of the monolayer composite article.

5. Process for the production of a monolayer composite article according to claim 4, wherein the increase in the transport velocity is accomplished by transporting the fibers over at least a first and at least a subsequent second transportation roll, the second transportation roll having a tangential velocity at its surface that is higher than the tangential velocity at its surface of the first roll.

6. Process for the production of a monolayer composite article according to claim 4, wherein the increase in transport velocity is at most a factor of 3.

7. Process for the production of a monolayer composite article according to claim 4, wherein the increase in transport velocity is at least a factor of 1.05.

8. Process for the production of a monolayer composite article according to claim 1, wherein the step of stretching the fibers is after the consolidation of the fibers.

9. Process for the production of a cross-layered composite article whereby at least one pair of monolayer composite articles according claim 1 is stacked whereby the fiber direction in each monolayer composite article is rotated with respect to the fiber direction in an adjacent monolayer.

10. Process according to claim 1, wherein the high performance polyolefin fibers have a strength of at least 1.2 GPa and a modulus of at least 40 GPa.

11. Process according to claim 1, wherein the high performance polyolefin fibers are obtained by the gel spinning process.

12. Process or article according to claim 11, wherein the high performance polyolefin fibers are fibers of high molecular weight linear polyethylene having a weight average molecular weight of at least 400,000 g/mol.

Description

EXAMPLE 1

[0050] Comparative experiment A was repeated, however during the production of the monolayer composite article, before the application of the matrix material, the fibers in the monolayer composite article were stretched with a stretch ratio of 1.33. The areal density of the ply was 113 g/m2, and the ballistic-resistant article comprised 18 plies. Results are presented in table 1.

EXAMPLE 2

[0051] Comparative experiment A was repeated, however during the production of the monolayer composite article, before the application of the matrix material, the fibers in the monolayer composite article were stretched with a stretch ratio of 1.44. The areal density of the monolayer composite article was 105 g/m2, and the ballistic-resistant article comprised 19 plies. Results are presented in table 1.

EXAMPLE 3

[0052] Comparative experiment B was repeated, however during the production of the monolayer composite article, before the application of the matrix material, the fibers in the monolayer composite article were stretched with a stretch ratio of 1.33. The areal density of the ply was 195 g/m2, and the ballistic-resistant article comprised 10 plies. Results are presented in table 1.

EXAMPLE 4

[0053] Comparative experiment B was repeated, however during the production of the monolayer composite article, before the application of the matrix material, the fibers in the monolayer composite article were stretched with a stretch ratio of 1.44. The areal density of the ply was 180 g/m2, and the ballistic-resistant article comprised 11 plies. Results are presented in table 1.

TABLE-US-00001 Comparative Stretch ratio Stretch ratio at V.sub.50 SEA exp./Example () break. (m/s) (J/(kg/m2)) A 1 1.58 375 280 B 1 1.63 355 251 1 1.33 1.28 425 365 2 1.44 1.19 449 403 3 1.33 1.29 461 422 4 1.44 1.20 477 455

[0054] It is clear from the results in table 1 that considerable improved values for the v.sub.50 and the SEA are obtained, which values are higher than those ever obtained before.