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AssigneeDsm IP Assets B.V.
InventorsJoseph Arnold Paul Maria SIMMELINK, Jacobus Johannes MENCKE, Martinus Johannes Nicolaas JACOBS, Roeloef MARISSEN
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Processes for making high-performance polyethylene multi-filament yarn are disclosed which include the steps of a) making a solution of ultra-high molar mass polyethylene in a solvent; b) spinning of the solution through a spinplate containing at least 5 spinholes into an air-gap to form fluid filaments, while applying a draw ratio DRfluid; c) cooling the fluid filaments to form solvent-containing gel filaments; d) removing at least partly the solvent from the filaments; and e) drawing the filaments in at least one step before, during and/or after said solvent removing, while applying a draw ratio DRsolid of at least 4, wherein in step b) each spinhole comprises a contraction zone of specific dimension and a downstream zone of diameter Dn and length Dn with Ln/Dn of from 0 to at most 25, to result in a draw ratio DRfluid=DRsp*DRag of at least 150, wherein DRsp is the draw ratio in the spinholes and DRag is the draw ratio in the air-gap, with DRsp being greater than 1 and DRag at least 1. High-performance polyethylene multifilament yarn, and semi-finished or end-use products containing said yarn, especially to ropes and ballistic-resistant composites, are also disclosed.
A ballistic resistant assembly comprising a plurality of preformed sheets, each preformed sheet comprising 2 layers of filaments from multifilament polyethylene yarn, the polyethylene having an IV of between 8 and 40 dL/g as measured on decalin solutions at 135° C., the plurality of preformed sheets having an areal density of at least 1.5 kg/m2 and at most 4.3 kg/m2, wherein the plurality of preformed sheets has a specific energy absorption of between 243 and 479 J·kg/m2 as measured against a 9*19 mm FMJ Parabellum FMJ bullet based on Stanag 2920.
A ballistic resistant assembly comprising a plurality of preformed sheets, each preformed sheet comprising 2 layers of filaments from multifilament polyethylene yarn, the polyethylene having an IV of between 8 and 40 dl/g as measured on decalin solutions at 135° C., the plurality of preformed sheets having an areal density of at least 1.5 kg/m2 and at most 4.3 kg/m2, wherein the ballistic resistant assembly has a specific energy absorption of between 243 and 479 J·kg/m2 as measured against a 9*19 mm FMJ Parabellum FMJ bullet based on Stanag 2920.
A preformed sheet comprising 2 layers of the ballistic resistant assembly of any preceding claim, each mono-layer comprising filaments from multifilament polyethylene yarn, wherein the filaments of the multifilament yarn in the 2 layers are spread unidirectionally, and wherein the filaments in each layer are rotated in a direction with respect to the direction of the filaments in an adjacent layer.
A preformed sheet comprising
Dependencies are inferred from the claim text.