Material sheet and process for its preparation

Abstract

The invention relates to a material sheet comprising a woven fabric of polymer tapes, wherein the width of a tape varies less than 2% on average in the longitudinal direction of the tape. The invention also relates to a process for the preparation of the material sheet, and to a ballistic resistant article comprising the material sheet. A ballistic resistant article comprising the material sheet exhibits excellent antiballistic properties.

1 . Material sheet comprising a woven fabric of unidirectional tapes of drawn polymer, wherein the width of a tape varies less than 2% on average in the longitudinal direction of the tape. 
     
     
         2 . Material sheet according to  claim 1 , wherein the woven fabric comprises a plurality of unidirectional tapes of the drawn polymer in the warp and weft direction, and wherein the gap between adjacent tapes in the weft and/or warp direction is smaller than 10% of the width of the adjacent unidirectional tapes. 
     
     
         3 . Material sheet according to  claim 1 , wherein the longitudinal edges of adjacent tapes in the weft and/or warp direction at least partially fixedly abut each other. 
     
     
         4 . Material sheet according to  claim 1 , wherein the unidirectional tapes in the weft and/or warp direction are mutually bonded, at least over an area adjacent to the longitudinal edges of the woven fabric. 
     
     
         5 . Material sheet according to  claim 4 , wherein the bonded area comprises a binder. 
     
     
         6 . Material sheet according to  claim 1 , wherein the woven fabric has a plain weave structure. 
     
     
         7 . Material sheet according to  claim 1 , wherein the strength of at least one unidirectional tape is at least 0.9 GPa. 
     
     
         8 . Material sheet according to  claim 1 , wherein the polymer is selected from the group consisting of polyolefins, polyesters, polyvinyl alcohols, polyacrylonitriles, polyamides, especially poly(p-phenylene teraphthalamide), liquid crystalline polymers and ladder-like polymers, such as polybenzimidazole or polybenzoxazole, especially poly(1,4-phenylene-2,6-benzobisoxazole), or poly(2,6-diimidazo[4,5-b-4′,5′-e]pyridinylene-1,4-(2,5-dihydroxy)phenylene). 
     
     
         9 . Process for the preparation of a material sheet according to  claim 1 , comprising:
 (a) providing a plurality of drawn polymer tapes having a width that varies less than 2% on average in the longitudinal direction of the tape;   (b) weaving said plurality of drawn polymer tapes to form a woven fabric;   (c) compressing the thus formed woven fabric at least over an area adjacent to the longitudinal edges of the woven fabric to consolidate the area.   
     
     
         10 . Process for the manufacture of a ballistic resistant article comprising:
 (a) stacking at least one material sheet according to  claim 1  and a sheet of material selected from the group consisting of ceramic, steel, aluminum, titanium, glass and graphite, or combinations thereof; and   (b) consolidating the stacked sheets under temperature and pressure.   
     
     
         11 . A ballistic resistant article comprising a material sheet according to  claim 1 . 
     
     
         12 . Ballistic resistant article according to  claim 11 , whereby a bonding layer is present between the further sheet of inorganic material and the material sheet, the bonding layer comprising a woven or non woven layer of inorganic fiber. 
     
     
         13 . Use of the material sheet according to  claim 1  in hard ballistic applications. 
     
     
         14 . A polymeric tape having a width that varies less than 2% on average in the longitudinal direction of the tape. 
     
     
         15 . A process for the preparation of the tape according to  claim 14 , the process comprising forming a polymeric powder bed, compression-moulding the polymeric powder bed at a temperature below the melting point of the polymeric powder, and preferably drawing the compression-moulded polymer, and wherein the powder bed is moulded by compression together with at least one compressible bordering means positioned onto the powder bed.