Acrylic polyvinyl acetal films & composition

Abstract

A film is described comprises a (meth)acrylic polymer and a polyvinyl acetal (e.g. butyral) resin. In some embodiments, the film has a glass transition temperature (i.e. Tg) ranging from 30° C. to 60° C. In some embodiments, the film has a gel content of at least 20% or greater. In some embodiments, the film has an elongation at break of at least 175%. The film typically comprises photoinitiator as a result of the method by which the film was made. The film may be a monolithic film or a layer of a multilayer film.

What is claimed is: 
     
         1 . A film comprising:
 (meth)acrylic polymer and polyvinyl acetal resin comprising polymerized units having the following formula   
       
         
           
           
               
               
           
         
         wherein R 1  is hydrogen or a C1-C7 alkyl group; 
         wherein the film has a Tg ranging from 30° C. to 60° C. 
       
     
     
         2 . The film of  claim 1  wherein the film comprises at least 10, 15, 20 or 25 wt-% of polymerized units of monofunctional alkyl (meth)acrylate monomer having a Tg of less than 0° C. 
     
     
         3 . The film of  claim 2  wherein the film comprises no greater than 60 wt-% of polymerized units of monofunctional alkyl (meth)acrylate monomer having a Tg of less than 0° C. 
     
     
         4 . The film of  claim 2  wherein the monofunctional alkyl (meth)acrylate monomer has a Tg of less than −10° C., −20° C., −30° C., or −40° C. 
     
     
         5 . The film of  claim 1  wherein the film comprises a bio-based content of at least 10, 15, 20 or 25% of the total carbon content. 
     
     
         6 . The film of  claim 1  wherein the film comprises polymerized units of an alkyl (meth)acrylate monomer having an alkyl group with 8 carbon atoms. 
     
     
         7 . The film of  claim 1  wherein the film further comprises up to 35 wt-% of polymerized units of a monofunctional alkyl (meth)acrylate monomer having a Tg greater than 40° C., 50° C., 60° C., 70° C., or 80° C. 
     
     
         8 . The film of  claim 1  wherein the film further comprises at least 10, 15 or 20 wt-% and no greater than 65 wt-% of polymerized units of polar monomers. 
     
     
         9 . The film of  claim 8  wherein polar monomers are selected from acid-functional, hydroxyl functional monomers, nitrogen-containing monomers, and combinations thereof. 
     
     
         10 . The film of  claim 1  wherein the film comprises polyvinyl butyral. 
     
     
         11 . The film of  claim 1  wherein the film comprises 5 to 30 wt-% of polyvinyl acetal resin. 
     
     
         12 . The film of  claim 1  wherein the polyvinyl acetal resin has a polyvinyl alcohol content ranging from 10 to 30. 
     
     
         13 . The film of  claim 1  wherein the polyvinyl acetal resin has a glass transition temperature ranging from 60° C. to 75° C. 
     
     
         14 . The film of  claim 1  wherein the polyacetal resin has an average molecular weight (Mw) ranging from 20,000 g/mole to 75,000 g/mole. 
     
     
         15 . The film of  claim 1  wherein the film further comprises polymerized units of a multifunctional crosslinker wherein the crosslinker comprises functional groups selected from (meth)acrylate, alkenyl, and hydroxyl-reactive groups. 
     
     
         16 . The film of  claim 1  wherein the film further comprises additives in an amount no greater than 25 wt-%. 
     
     
         17 . The film composition of  claim 1  wherein the film composition comprises photoinitiator. 
     
     
         18 . The film composition of  claim 1  wherein the film comprises no greater than 10 wt-% of polymerized units of methacrylate monomers. 
     
     
         19 . The film composition of  claim 1  wherein the (meth)acrylic polymer is a random copolymer. 
     
     
         20 . The film of  claim 1  wherein the film is a monolithic or multilayer film.