Ballistic resistant article comprising a styrene butadiene resin and process to manufacture said article
A ballistic resistant article is presented comprising a plurality of fibrous layers, each of said layers comprising a network of fibers, wherein the fibers have a strength of at least 800 mN/tex (1100 MPa) according to ASTM D 7269-07 and a matrix material, wherein the matrix material comprises a mixture comprising: at least one styrene butadiene random copolymer resin, and at least one tackifier. Compared with an article of the same construction but with a matrix material without a tackifier the article according to the invention comprises a higher adhesion between the fibrous layers both in the unaged and aged state and a lower water pick up after water soak. The article additionally comprising a plate of metal or ceramic exhibits minimal or even no delamination of the fibrous layers after ballistic attack. In contrast an article of the same construction but with a matrix material without the styrene butadiene random copolymer resin exhibits (very strong) interior delamination of the fibrous layers and the article of the same construction with the styrene butadiene random copolymer resin, but without the tackifier as the matrix material exhibits light delamination.
1. A ballistic resistant article comprising a plurality of fibrous layers, each of said layers comprising a network of fibers, wherein the fibers have a strength of at least 800 mN/tex (1100 MPa) according to ASTM D 7269-07 and a matrix material, wherein the matrix material comprises a mixture
comprising
at least one styrene butadiene random copolymer resin, and
at least one tackifier.
2. The ballistic resistant article according to claim 1 , wherein the styrene butadiene random copolymer resin is a carboxylated styrene butadiene random copolymer resin.
3. The ballistic resistant article according to claim 1 , wherein the styrene butadiene random copolymer resin is a non-carboxylated styrene butadiene random copolymer resin.
4. The ballistic resistant article according to claim 1 , wherein the tackifier is selected from the group consisting of rosin resins or terpene resins or hydrocarbon resins.
5. The ballistic resistant article according to claim 1 , wherein the tackifier is present in the matrix material in a weight percentage with respect to the weight of the matrix material ranging from 1 wt. % to 20 wt. %.
6. The ballistic resistant article according to claim 5 , wherein the at least one tackifier is present in the matrix material in the weight percentage with respect to the weight of the matrix material ranging from 1 wt. % to 20 wt. % to reduce water pickup in comparison to a ballistic resistant article of the same construction but without the tackifier.
7. The ballistic resistant article according to claim 5 , wherein the at least one tackifier is present in the matrix material in the weight percentage with respect to the weight of the matrix material ranging from 1 wt. % to 20 wt. % to reduce delamination of the plurality of fibrous layers upon ballistic attack in comparison to a ballistic resistant article of the same construction but without the tackifier.
8. The ballistic resistant article according to claim 1 , wherein the network of fibers is a unidirectional alignment of the fibers.
9. The ballistic resistant article according to claim 1 , wherein the fibers are aramid fibers.
10. The ballistic resistant article according to claim 1 , wherein the fibers have a weight wf, the matrix material has a weight wm and a weight percentage of the matrix material with respect to (wf+wm) is from 5 wt. % to 50 wt. %.
11. The ballistic resistant article according article to claim 1 , wherein the areal density of the fibers in a single fibrous layer ranges from 10 g/m 2 to 250 g/m 2 .
12. The ballistic resistant article according to claim 1 , wherein the total areal density of a single fibrous layer ranges from 11 g/m 2 to 350 g/m 2 .
13. The ballistic resistant article according to claim 1 , wherein the plurality of fibrous layers is formed into a panel and the panel is joined to a plate of metal or ceramic.
14. Ballistic resistant article according to claim 1 , wherein a scrim comprising a thermoplastic material is situated between the fibrous layers.
15. A process to manufacture a ballistic resistant article comprising the steps:
(1) Manufacture of a single unidirectional fibrous layer, each of said layers comprising a network of fibers, wherein the fibers have a strength of at least 800 mN/tex (1100 MPa) according to ASTM D 7269-07, and comprising a matrix material, which comprises a mixture comprising
at least one styrene butadiene random copolymer resin,
and at least one tackifier,
(2) manufacture of an adherent cross-ply from at least two unidirectional single fibrous layers resulting from step (1),
(3) manufacture of a consolidated panel from a number of adherent cross-plies resulting from step (2), and optionally
(4) joining of the consolidated panel resulting from step (3) to a plate of metal or ceramic to yield a hard-ballistic resistant article.
16. The process according to claim 15 , wherein in step (1) the styrene butadiene random copolymer resin is a non-carboxylated styrene butadiene random copolymer resin.
17. The process according to claim 15 , wherein in step (1) the styrene butadiene random copolymer resin is a carboxylated styrene butadiene random copolymer resin.
18. The process according to claim 15 , wherein a cross-linking reaction of the at least one styrene butadiene random copolymer resin is comprised in at least one of the steps (1), (2) and (3).