Process for producing a polymer tape from a powder
The invention relates to a process for the production of a non-fibrous drawn polymer tape, said process comprising the steps: a) compacting a polymer powder in a press to form a compacted polymer bed; b) calendering said compacted polymer bed to form an oriented polymer tape; and c) drawing said oriented polymer tape to form a highly oriented polymer tape; characterized in that step a) comprises compacting the polymer powder at a temperature and pressure such that from 0.1 to 20 wt. % of the polymer powder as measured by DSC is melted. The invention also relates to a tape obtainable by the above process, and a monolayer, multilayered material sheet and ballistic resistant article comprising such a tape.
1. A process for the production of a non-fibrous drawn polymer tape, said process comprising the steps:
a) forming a compacted polymer bed by compacting a polymer powder which comprises ultra-high molecular weight polyethylene (UHMWPE) at a temperature and pressure such that from 1 to 20 wt. % of the polymer powder as measured by Differential Scanning Calorimetry (DSC) is melted;
b) calendering said compacted polymer bed to form an oriented polymer tape; and
c) drawing said oriented polymer tape to form a highly oriented polymer tape.
2. The process according to claim 1 , wherein step a) is practiced such that from 1 to 5 wt. % of the polymer powder is melted.
3. The process according to claim 1 , wherein the polymer powder is compacted in a double belt press.
4. The process according to claim 1 , wherein the polymer powder comprises particles having an average particle size of up to 1000 μm.
5. The process according to claim 4 , wherein the UHMWPE powder comprises polyethylene having an intrinsic viscosity greater than 5 dl/g.
6. A non-fibrous drawn polymer tape obtained by the process according to claim 1 .
7. A monolayer comprising a plurality of uniaxially aligned non-fibrous polymer tapes, wherein each tape is the non-fibrous drawn polymer tape according to claim 6 .
8. A monolayer comprising a plurality of woven non-fibrous polymer tapes, wherein each tape is the non-fibrous drawn polymer tape according to claim 6 .
9. A multilayered material sheet comprising a consolidated stack of monolayers, wherein each monolayer is the monolayer according to claim 7 .
10. A ballistic resistant article comprising a multilayered material sheet according to claim 9 and a further material sheet, wherein the material of the further material sheet is a metal or metal alloy selected from the group consisting of steel, aluminum, magnesium, titanium, nickel, chromium, and iron, and/or a non-metal selected from the group consisting of ceramic, glass, graphite, and combinations thereof.
11. A process for producing a monolayer comprising:
(i) forming a parallel arrangement of tapes by arranging a plurality of the non-fibrous drawn polymer tapes according to claim 6 in parallel such that adjacent tapes partially overlap; and
(ii) consolidating the parallel arrangement under pressure and at a temperature such that at least a portion of the polymer forming the tapes melts as determined by DSC.
12. A process for producing a monolayer comprising:
(i) forming a woven arrangement of tapes by weaving a plurality of the non-fibrous drawn polymer tapes according to claim 6 ; and
(ii) consolidating the woven arrangement of tapes under pressure and at a temperature such that at least a portion of the polymer forming the tapes melts as determined by DSC.
13. A process for producing a multilayered material sheet comprising:
(i) stacking a plurality of the monolayers according to claim 7 , and
(ii) consolidating the stack of monolayers under pressure and at a temperature such that at least a portion of the polymer of the monolayers melts as determined by DSC.
14. A process for producing a ballistic resistant article comprising:
(i) stacking a plurality of the monolayers according to claim 7 together with a further material sheet, wherein the material of the further material sheet is a metal or metal alloy selected from the group consisting of steel, aluminum, magnesium, titanium, nickel, chromium, and iron, and/or a non-metal selected from the group consisting of ceramic, glass, graphite, and combinations thereof, and
(ii) consolidating the stack of the monolayers and further material sheet under pressure and at a temperature such that at least a portion of the polymer forming the monolayers melts as determined by DSC.