Surface veil of oxidized PAN fiber

Abstract

A nonwoven veil comprising an oxidized PAN fiber having an aromaticity index between 40 and 60 percent, wherein the veil is thermally stable in temperature ranges used for typical composite fabrication processes. Thermally stable nonwoven veil and composites containing the veil are disclosed. The nonwoven veil could be used as a surface finish having improved properties as measured by surface waviness and lack of defects.

1 . A nonwoven veil comprising an oxidized PAN fiber having an aromaticity index between 40 and 60 percent, wherein the oxidized PAN fiber exhibits thermal stability from room temperature to 260° C. such that the oxidized PAN fiber has substantially negligible shrinkage up to 260° C.  
   
   
       2 . The veil of  claim 1 , wherein the veil has a substantially uniform and quasi-isotropic fiber structure.  
   
   
       3 . The veil of  claim 1 , wherein a content of the oxidized PAN fiber is between 85 and 100 percent by weight of the veil.  
   
   
       4 . The veil of  claim 1 , wherein a content of a secondary fiber is between 0 and 15 percent by weight of the veil.  
   
   
       5 . The veil of  claim 4 , wherein the secondary fiber is a thermofusible fiber.  
   
   
       6 . The veil of  claim 4 , wherein the secondary fiber is a bi-component thermofusible binder.  
   
   
       7 . The veil of  claim 6 , wherein a content of thermofusible binder is between 0 and 15 percent by weight.  
   
   
       8 . The veil of  claim 1 , wherein an area weight of the veil is between 35 and 120 grams per square meter.  
   
   
       9 . The veil of  claim 1 , wherein the oxidized PAN fiber has a linear density between 1.2 and 6.0 dtex.  
   
   
       10 . The veil of  claim 1 , wherein the oxidized PAN fiber has a linear density between 1.5 and 2.4 dtex.  
   
   
       11 . The veil of  claim 1 , wherein the oxidized PAN fiber is a crimped staple fiber.  
   
   
       12 . The veil of  claim 1 , wherein the veil is made by a textile process selected from the group consisting of hydro-entanglement and needle-punching.  
   
   
       13 . The veil of  claim 1 , wherein the oxidized PAN fiber is substantially non-thermoplastic.  
   
   
       14 . The veil of  claim 1 , wherein the oxidized PAN fiber has shrinkage in the range of about 0-13 percent at an elevated temperature between 260° C. and 730° C.  
   
   
       15 . The veil of  claim 1 , wherein the oxidized PAN fiber has shrinkage of about zero percent at a temperature between room temperature to about 260° C.  
   
   
       16 . A fiber reinforced plastic composite material comprising the veil of  claim 1 .  
   
   
       17 . The fiber reinforced plastic composite material of  claim 16  comprising a thermosetting resin.  
   
   
       18 . The fiber reinforced plastic composite material of  claim 16  comprising a thermoplastic resin.  
   
   
       19 . The fiber reinforced plastic composite material of  claim 16 , wherein the veil of is preformed using an elevated temperature that activates a thermofusible component.  
   
   
       20 . The fiber reinforced plastic composite material of  claim 16 , wherein the veil is thermally bonded to a reinforcement material.  
   
   
       21 . The fiber reinforced plastic composite material of  claim 16 , wherein the veil is stitch bonded to a reinforcement material.  
   
   
       22 . The fiber reinforced plastic composite material of  claim 16 , wherein the veil is combined with a reinforcement material and a resin.  
   
   
       23 . The fiber reinforced plastic composite material of  claim 16 , wherein the composite material is made by a molding process comprising a step at an elevated temperature above the room temperature.  
   
   
       24 . The fiber reinforced plastic composite material of  claim 16 , wherein the composite has substantially no global distortion.  
   
   
       25 . The fiber reinforced plastic composite material of  claim 16 , wherein the veil does not substantially print-through the composite material.