Exterior window film

Abstract

A transparent exterior window film composite comprising a base sheet material having an outer PET (polyethylene terephthalate) film layer which has been surface treated to elevate adhesion thereto and which is impregnated with an ultra violet light absorber (UVA), the treated surface being coated with a UV stabilized acrylic polymer or co-polymer undercoat having a UV stabilized hard coat layer thereon formed from at least one aliphatic urethane acrylate oligomer and at least one multifunctional acrylate monomer, the primer layer having a thickness which is at least as thick as the hard coat.

1 . A transparent exterior window film composite comprising a base sheet material having an outer PET (polyethylene terephthalate) film layer which has been surface treated to elevate adhesion thereto and which is impregnated with an ultra violet light absorber (UVA), the treated surface being coated with an acrylic polymer or co-polymer undercoat having a urethane-acrylate hard coat layer thereon formed from at least one urethane acrylate oligomer and at least one multifunctional acrylate monomer, the primer layer having a thickness which is at least as thick as the hard coat. 
   
   
       2 . A film composite as claimed in  claim 1  wherein the outer PET film layer of the base sheet material is between ½-7 mil (0.0125-0.18 mm) thick and contains UVA to absorb at least 99% of ultra violet light. 
   
   
       3 . A film composite as claimed in  claim 1  wherein the undercoat comprises a coating of at least one cured acrylic based resin or a urethane-acrylic based resin containing UV stabilizer. 
   
   
       4 . A film composite as claimed in  claim 3 , wherein the undercoat contains up to 5% by weight of UV absorber. 
   
   
       5 . A film composite as claimed in  claim 3 , wherein the undercoat contains up to 3% by weight of organic UV absorber or up to 5% by weight of inorganic UV absorber. 
   
   
       6 . A film composite as claimed in  claim 3 , wherein the undercoat has a thickness of between 6 and 20 microns. 
   
   
       7 . A film composite as claimed in  claim 6 , where the undercoat has a thickness of between 6 and 12 microns. 
   
   
       8 . A film composite as claimed in  claim 1 , wherein the urethane acrylate oligomer comprises an aliphatic acrylate urethane oligomer having a glass transition temperature, or Tg, higher than 80° C. with an elongation less than 10%, preferably less than 5%. 
   
   
       9 . A film composition as claimed in  claim 1  wherein the multifunctional acrylate monomer comprises dipentaerythritol pentaacrylate. 
   
   
       10 . A film composite as claimed in  claim 1 , in which the hardcoat comprises at least two multifunctional acrylate monomers comprising dipentaerythritol pentaacrylate and tricyclodecane dimethanol diacrylate. 
   
   
       11 . A film composite as claimed in  claim 1  wherein the undercoat has a thickness of between 6 and 20 microns and the hard coat has a thickness of between 6-8 microns. 
   
   
       12 . A film composite as claimed in  claim 3 , wherein the urethane acrylate oligomer comprises an aliphatic urethane acrylate oligomer having a glass transition temperature, or Tg, higher than 80° C. with an elongation less than 10%, preferably less than 5% and at least two multifunctional acrylate monomers comprising dipentaerythritol pentaacrylate and tricyclodecane dimethanol diacrylate, the undercoat having a thickness of between 6 and 20 microns and the hard coat has a thickness of between 6-8 microns. 
   
   
       13 . A film composite as claimed in  claim 8 , wherein the hard coat is made hydrophobic by the addition of up to 4% by weight of a hydrophobic material additive. 
   
   
       14 . A film composite as claimed in  claim 1 , wherein the hard coat may contain a nanoparticle dispersion therein. 
   
   
       15 . A film composite as claimed in  claim 1 , wherein the base sheet material on its other surface of the polymeric film may be coated with a pressure sensitive adhesive which adheres to the PET film layer and in use may adhere the composite to glazing. 
   
   
       16 . A film composite as claimed in  claim 15 , wherein the adhesive is covered with a release liner. 
   
   
       17 . A film composite as claimed in  claim 1 , wherein the film composite has a visible light transmission in the range of 5-85% VLT. 
   
   
       18 . A film composite as claimed in  claim 1  and which when tested for adhesion after exposure to weather testing in accordance with ASTM G 155 exceeds 1200 hours before adhesion failure between the hard coat and the base material. 
   
   
       19 . A film composite as claimed in  claim 12 , when tested for adhesion after exposure to weather testing in accordance with ASTM G 155 has a life between 1500-2400 hours before failure between the hard coat and the base material. 
   
   
       20 . A film composite as claimed in  claim 12 , cured in inert conditions and which when tested for adhesion after weather testing in accordance with ASTM G 155 exceeds 3000 hours before failure between the hard coat and the base material. 
   
   
       21 . A film composite as claimed in  claim 5 , wherein the urethane oligomer comprises an aliphatic urethane acrylate oligomer having a glass transition temperature, or Tg, higher than 80° C. with an elongation less than 10%, preferably less than 5% and at least two multifunctional acrylate monomers comprising dipentaerythritol pentaacrylate and tricyclodecane dimethanol diacrylate, the undercoat having a thickness of between 6 and 20 microns and the hard coat has a thickness of between 6-8 microns.