Impact resistant composite material

Abstract

The invention relates to a preformed sheet with an improved ballistic resistance, comprising a network of fibers having a tensile strength of at least 1.5 GPa, impregnated with at least 10% of a plastic material comprising a multiphase (meth)acrylic based polymer dispersion. Such polymer dispersion has a first phase which has a minimum glass transition temperature of at least 40° C. and a weight average molecular weight of less than 80,000 g/mol and a second phase having a maximum glass transition temperature of 30° C. or less and a weight average molecular weight of more than 100,000 g/mol.

1 . Preformed sheet, comprising a network of fibers having a tensile strength of at least 1.5 GPa, impregnated with at least 10% of a plastic material, characterized in that the plastic material comprises a multiphase (meth)acrylic based polymer dispersion with a first phase having a minimum glass transition temperature of at least 40° C. and a weight average molecular weight of less than 80,000 g/mol and a second phase having a maximum glass transition temperature of 30° C. or less and a weight average molecular weight of more than 100,000 g/mol. 
     
     
         2 . Preformed sheet according to  claim 1 , wherein the oligomer has a glass transition temperature of at least 30° C. below the glass transition temperature of the polymer. 
     
     
         3 . Preformed sheet according to  claim 1 , wherein multiphase polymer dispersion forms a core-shell structure. 
     
     
         4 . Preformed sheet according to  claim 1 , wherein the network of fibers comprises a fabric. 
     
     
         5 . Preformed sheet according to  claim 1 , wherein the network of fibers comprises unidirectionally aligned fibers. 
     
     
         6 . Preformed sheet according to  claim 1 , wherein the fibers are UHMWPE fibers. 
     
     
         7 . Preformed sheet according to  claim 1 , wherein the preformed sheet comprises a separating film on at least one of its outer surfaces. 
     
     
         8 . Preformed sheet according to  claim 7 , wherein the separating film is a biaxially stretched polyolefin film. 
     
     
         9 . Assembly of at least two preformed sheets according to  claim 1 , which sheets are substantially not linked to one another. 
     
     
         10 . Ballistic resistant article comprising at least one assembly according to  claim 9 . 
     
     
         11 . Ballistic resistant article comprising a plurality of preformed sheets according to  claim 2  having an Eabs of more than 115 J/kg/m 2  for 9 mm*19 Natoball DM11 A1B2 bullets. 
     
     
         12 . Ballistic resistant article according to  claim 11 , further comprising at least two networks of unidirectionally aligned fibers with optionally a matrix. 
     
     
         13 . Ballistic resistant article according to  claim 12 , wherein the matrix for the unidirectional aligned fibers comprises a modified polyolefin, a SIS, or a SEBS. 
     
     
         14 . Ballistic resistant article according to  claim 12 , wherein the matrix for the unidirectional aligned fibers is an acrylic based thermoplastic polymer forming a first phase, further comprising an oligomer in a second phase, wherein the polymer has a glass transition temperature of at least 25° C. 
     
     
         15 . Use of a plastic material comprising a multiphase (meth)acrylic based polymer dispersion with a first phase having a minimum glass transition temperature of at least 40° C. and a weight average molecular weight of less than 80,000 g/mol and a second phase having a maximum glass transition temperature of 30° C. or less and a weight average molecular weight of more than 100,000 g/mol, in the manufacture of ballistic resistant composites.