Ballistic-resistant moulded article and a process for the manufacture of the moulded article

• US 6,893,704 B1
• Filed: 09/21/2000
• Issued: 05/17/2005
• Est. Priority Date: 06/20/1995
• Status: Expired due to Fees

• Current Assignee: DSM IP Assets BV (DSM-Firmenich AG)
• Original Assignee: DSM IP Assets BV (DSM-Firmenich AG)
• Inventors: van der Loo, Leonardus L. H.
• Primary Examiner(s): SINGH-PANDEY, ARTI R
• Application Number:
  US09/666,189
• Time in Patent Office: 1,699 Days
• Field of Search: 2/25, 428/911, 428/105, 428/107, 428/219, 428/112, 428/294.7, 442/134, 442/135, 442/239, 442/255, 442/261, 442/286, 264/241, 264/250, 264/263
• US Class Current: 428/107
• CPC Class Codes: B29C 70/202 arranged in parallel planes or structures of fibres crossing at substantial angles, e.g. cross-moulding compound [XMC] B29C70/207 takes precedence
• CPC Class Codes: B29C 70/30 Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core
• CPC Class Codes: F41H 5/0485 all the layers being only fibre- or fabric-reinforced layers
• CPC Class Codes: Y10T 428/24058 including grain, strips, or filamentary elements in respective layers or components in angular relation
• CPC Class Codes: Y10T 428/24074 Strand or strand-portions
• CPC Class Codes: Y10T 428/24116 Oblique to direction of web
• CPC Class Codes: Y10T 428/249932 Fiber embedded in a layer derived from a water-settable material [e.g., cement, gypsum, etc.]
• CPC Class Codes: Y10T 442/2615 Coating or impregnation is resistant to penetration by solid implements
• CPC Class Codes: Y10T 442/2623 Ballistic resistant
• CPC Class Codes: Y10T 442/3472 Woven fabric including an additional woven fabric layer
• CPC Class Codes: Y10T 442/3602 Three or more distinct layers
• CPC Class Codes: Y10T 442/365 At least one layer is a preformed synthetic polymeric film or sheet
• CPC Class Codes: Y10T 442/3854 Woven fabric with a preformed polymeric film or sheet

Abstract

The invention relates to a ballistic-resistant moulded article containing a compressed stack of monolayers, with each monolayer containing unidirectionally oriented reinforcing fibers and at most 30 wt. % of a plastic matrix material and with the fiber direction in each monolayer being rotated with respect to the fiber direction in an adjacent monolayer, characterized in that the density (ρ_p) of the compressed stack is at least 98.0% of the theoretical maximum density. The invention also relates to a process for manufacturing the moulded article.

The ballistic-resistant article may be used in, for instance, helmets, as inserts in bullet-proof vests, as armoring on military vehicles and in ballistic-resistant panels.

Claims

1. Ballistic-resistant molded article comprising a compressed stack of monolayers, with each monolayer containing unidirectionally oriented reinforcing fibers being high-drawn fibers of high-molecular-weight linear polyethylene and at most 20 wt. % of a plastic matrix material and with the fiber direction in each monolayer being rotated with respect to the fiber direction in an adjacent monolayer, the monolayers having a fiber weight between 25 and 150 g/m², and wherein the density (ρ

_p) of the compressed stack is at least 98.0% of the theoretical maximum density.

2. Ballistic-resistant molded article according to claim 1, wherein the density ρ

_p is at least 99.0% of the theoretical maximum density.

3. Ballistic-resistant molded article according to claim 1, wherein the reinforcing fibers in the monolayer have a tensile strength of at least 1.2 GPa and a tensile modulus of at least 40 GPa.

4. Ballistic-resistant molded article according to claim 1, wherein the plastic matrix material is an elastomer with a tensile modulus (at 25°

C.) of at most 41 MPa.

5. Ballistic-resistant molded article according to claim 1, wherein the rotation amounts to 90 degrees.

6. Ballistic-resistant molded article according to claim 1, wherein the molded article has a specific energy absorption (SEA) of at least 75 Jm²/kg on impact of a 7.62×

39 Mild Steel Core P.S. Ball M1943 bullet.

7. Ballistic-resistant molded article according to claim 1, wherein the molded article has a specific energy absorption (SEA) of at least 110 Jm²/kg on impact of a 7.62×

39 Mild Steel Core P.S. Ball M1943 bullet.

9. Ballistic-resistant molded article according to claim 5, wherein the density (ρ

_p) of the compressed stack is at least 98.0% of the theoretical maximum density.

8. Ballistic-resistant molded article having an areal density of between 10 and 40 kg/m², comprising a compressed stack of monolayers, with each monolayer containing unidirectionally oriented reinforcing fibers being high-drawn fibers of high-molecular-weight linear polyethylene and at most 20 wt. % of a plastic matrix material and with the fiber direction in each monolayer being rotated with respect to the fiber direction in an adjacent monolayer, wherein the molded article has a specific energy absorption (SEA) of at least 75 μ

m²/kg on impact of a 7.62×

39 Mild Steel Core P.S. Ball M1943 bullet.

10. Ballistic-resistant molded article according to claim 8, wherein the molded article has a specific energy absorption (SEA) of at least 110 Jm²/kg on impact of a 7.62×

39 Mild Steel Core P.S. Ball M1943 bullet.

11. Ballistic-resistant molded article according to claim 10, wherein the density (ρ

_p) of the compressed stack is at least 99.0% of the theoretical maximum density.

12. Process for manufacturing a ballistic resistant molded article from a stack comprising crosswise-arranged monolayers, with each monolayer containing unidirectionally oriented reinforcing fibers being high-drawn fibers of high-molecular weight linear polyethylene and at most 20 wt % of a plastic matrix material and with the fiber direction in each monolayer being rotated with respect to the fiber direction in an adjacent monolayer, the monolayers having a fiber weight between 25 and 150 μ

m², which comprises compressing the stack at an elevated temperature and at a pressure of at least 13 MPa, and cooling the compressed stack while under pressure.

13. Process according to claim 12, wherein the stack is compressed at a pressure of at least 15 MPa.

14. Process according to claim 12, wherein the reinforcing fibers in the monolayers have a cross-section aspect ratio of at most 3.

15. Process according to claim 12, wherein the monolayer has been obtained by impregnating the reinforcing fibers with an aqueous dispersion containing the plastic matrix material.

16. Process according to claim 12, wherein the monolayer has a fiber weight of between 50 and 150 g/m².

17. Process for manufacturing a ballistic-resistant molded article comprising forming a stack of semi-manufactured packages of cross-layered monolayers, said packages having an areal density of from 0.25 to 5 kg/m², with each monolayer containing unidirectionally oriented reinforcing fibers and at most 20 wt % of a plastic matrix material, said packages having been compressed at an elevated temperature and at a first pressure of at least 13 MPa and compressing said stack at an elevated temperature and at a second pressure, and cooling the compressed stack while still under pressure.

18. Process according to claim 17, wherein the second pressure is at most 5 MPa.

19. Process according to claim 17, wherein the monolayer packages each contain from 2 to 8 monolayers placed cross-wise with respect to each other.

20. Process according to claim 17, wherein the packages are compressed at a first pressure of at least 15 MPa.

21. Process according to claim 17, wherein the second pressure is at most 3 MPa.

22. Process according to claim 17, which further comprises forming said semi-manufactured packages by compressing at least two cross-layered monolayers at an elevated temperature and at a pressure of at least 13 MPa.

23. Process according to claim 17, wherein the stack is compressed under conditions to provide a density (ρ

_p) of at least 98.0% of the theoretical maximum density.

24. Process according to claim 17, wherein the stack is compressed under conditions to provide a density (ρ

_p) of at least 99.0% of the theoretical maximum density.

25. Process according to claim 17, wherein the stack is compressed under conditions to provide a specific energy absorption (SEA) of at least 75 Jm²/kg on impact of a 7.62×

39 Mild Steel Core P.S. Ball M1943 bullet.

26. Process according to claim 17, wherein the stack is compressed under conditions to provide a specific energy absorption (SEA) of at least 110 Jm²/kg on impact of a 7.62×

39 Mild Steel Core P.S. Ball M1943 bullet.

27. A semi-manufactured article useful for the manufacture of a ballistic-resistant molded article, comprising a compressed stack of cross-layered monolayers containing unidirectionally oriented reinforcing fibers and at most 20 wt % of a plastic matrix material, said article having an areal density of from 0.5 to 5 kg/m².

28. A semi-manufactured article according to claim 27, which comprises from 2 to 8 of said monolayers.

29. A semi-manufactured article according to claim 27, wherein each of said monolayers has a fiber weight of between 50 and 150 g/m².

30. A semi-manufactured article according to claim 27, wherein the areal density if from 0.5 to 2.5 kg/m².

31. A semi-manufactured article according to claim 27, wherein a monolayer has been obtained by impregnating the reinforcing fibers with an aqueous dispersion containing the plastic matrix material.