Surfacing film for composite structures

Abstract

A layered construction is provided having a storage modulus G′ t25 at 25° C., comprising: a) a cured polymeric composite having a storage modulus G′ s25 at 25° C.; and b) a cured surfacing film bound thereto; wherein G′ t25 is not greatly elevated over G′ s25 , typically not more than 118% of G′ s25 . In some embodiments the cured surfacing film comprises an electrically conductive layer, typically a metal layer. In some embodiments the cured surfacing film comprises a cured epoxy resin which may optionally be a chain-extended epoxy resin and may excludes phosphorus. The resulting layered construction may display high erosion resistance, high corrosion resistance, and high resistance to microcracking. In another aspect, methods of making the subject layered constructions are provided.

1 . A layered construction having a storage modulus G′ t25  at 25° C., comprising:
 a) a cured polymeric composite having a storage modulus G′ s25  at 25° C.; and   b) a cured surfacing film bound thereto;   
     wherein G′ t25  is no more than 118% of G′ s25 . 
   
   
       2 . The layered construction according to  claim 1  wherein G′ t25  is no more than 110% of G′ s25 . 
   
   
       3 . The layered construction according to  claim 1  wherein G′ t25  is no more than 104% of G′ s25 . 
   
   
       4 . The layered construction according to  claim 1  wherein G′ t25  is between 101% and 118% of G′ s25 . 
   
   
       5 . The layered construction according to  claim 1  having a storage modulus G′ t-54  at −54° C., wherein the cured polymeric composite has a storage modulus G′ s-54  at −54° C.; and wherein G′ t-54  is no more than 122% of G′ s-54 . 
   
   
       6 . The layered construction according to  claim 5  wherein G′ t-54  is between 101% and 122% of G′ s-54 . 
   
   
       7 . The layered construction according to  claim 1  wherein the cured surfacing film comprises an electrically conductive layer. 
   
   
       8 . The layered construction according to  claim 1  wherein the cured surfacing film comprises an electrically conductive metal layer. 
   
   
       9 . The layered construction according to  claim 1  wherein the cured surfacing film comprises a cured chain-extended epoxy resin. 
   
   
       10 . The layered construction according to  claim 1  wherein the cured surfacing film comprises no phosphorus. 
   
   
       11 . The layered construction according to  claim 1  wherein the cured polymeric composite comprises a matrix polymer which is a different composition from the cured surfacing film. 
   
   
       12 . A method of making a layered construction comprising the steps of:
 a) providing a curable polymeric composite which cures to form a cured polymeric composite having a storage modulus G′ s25  at 25° C.;   b) selecting a curable surfacing film;   c) providing said curable surfacing film;   d) providing a tool having a shape which is the inverse of the desired shape of the layered construction;   e) laying up the curable surfacing film and the curable polymeric composite, in that order, in the tool; and   f) curing the curable polymeric composite and curable surfacing film to make a layered construction, the layered construction having a storage modulus G′ t25  at 25° C.;   wherein step b) of selecting a curable surfacing film comprises selecting a film such that G′ t25  is not more than 118% of G′ s25 .   
   
   
       13 . The method according to  claim 12  wherein step b) of selecting a curable surfacing film comprises selecting a film such that G′ t25  is no more than 110% of G′ s25 . 
   
   
       14 . The method according to  claim 12  wherein step b) of selecting a curable surfacing film comprises selecting a film such that G′ t25  is no more than 104% of G′ s25 . 
   
   
       15 . The method according to  claim 12  wherein step b) of selecting a curable surfacing film comprises selecting a film such that G′ t25  is between 101% and 118% of G′ s25 . 
   
   
       16 . The method according to  claim 12  wherein the curable surfacing film comprises an electrically conductive layer. 
   
   
       17 . The method according to  claim 12  wherein the curable surfacing film comprises an electrically conductive metal layer. 
   
   
       18 . The method according to  claim 12  wherein the curable surfacing film comprises a cured chain-extended epoxy resin. 
   
   
       19 . The method according to  claim 12  wherein the curable surfacing film comprises no phosphorus. 
   
   
       20 . The method according to  claim 12  wherein the curable polymeric composite comprises a matrix polymer which is a different composition from the curable surfacing film.