Urethane-based pressure sensitive adhesives

Abstract

Non-silicone, urethane-based adhesives are disclosed which are prepared by the polymerization of reactive oligomers with the general formula X-A-B-A-X, where X is an ethylenically unsaturated group B is a unit free of silicone, and A is a urethane linkage. The adhesives are optically clear, self wetting and removable. Adhesive articles, including optical adhesive articles, may be prepared using the disclosed non-silicone urethane-based adhesives.

What is claimed is: 
     
         1 . An adhesive comprising a cured mixture comprising:
 at least one X-A-B-A-X reactive oligomer, wherein
 X comprises an ethylenically unsaturated group, 
 B comprises a non-silicone segmented unit with a number average molecular weight of 5,000 grams/mole or greater, and 
 A comprises a urethane linking group, wherein the X-A-B-A-X reactive oligomer is the reaction product of a HO—B—OH hydroxyl-capped prepolymer and an X—Z compound wherein Z is an isocyanate group and X is an ethylenically unsaturated group linked to the Z group; and 
   an initiator, wherein the adhesive is a pressure sensitive adhesive.   
     
     
         2 . The adhesive of  claim 1 , wherein the adhesive is a self-wetting and removable adhesive. 
     
     
         3 . The adhesive of  claim 1 , wherein cured mixture further comprises an ethylenically unsaturated material. 
     
     
         4 . The adhesive of  claim 1 , further comprising at least one additive, wherein the additive comprises a pressure sensitive adhesive, a plasticizing agent, a tackifying agent or a mixture thereof. 
     
     
         5 . The adhesive of  claim 4 , comprising 5-60 weight % of added pressure sensitive adhesive and 5-55 weight % plasticizer. 
     
     
         6 . The adhesive of  claim 5 , wherein the plasticizer comprises isopropyl myristate or polypropylene glygol. 
     
     
         7 . The adhesive of  claim 6 , wherein the added pressure sensitive adhesive comprises a (meth)acrylate pressure sensitive adhesive. 
     
     
         8 . The adhesive of  claim 7 , wherein the added pressure sensitive adhesive comprises an acid-containing (meth)acrylate pressure sensitive adhesive. 
     
     
         9 . A method of preparing an adhesive comprising:
 providing a curable composition comprising:
 at least one X-A-B-A-X reactive oligomer, wherein X comprises an ethylenically unsaturated group, B comprises a non-silicone unit with a number average molecular weight of 5,000 grams/mole or greater, and A comprises a urethane linkage; and 
 an initiator; and 
   curing the curable composition to form a pressure sensitive adhesive.   
     
     
         10 . The method of  claim 9 , wherein the X-A-B-A-X reactive oligomer is the reaction product of a HO—B—OH hydroxyl-capped prepolymer and an X—Z compound wherein Z is an isocyanate group and X is an ethylenically unsaturated group linked to the Z group. 
     
     
         11 . The method of  claim 9 , wherein the adhesive comprises a self-wetting and removable adhesive. 
     
     
         12 . The method of  claim 9 , wherein the adhesive comprises an optically clear adhesive. 
     
     
         13 . An adhesive article comprising:
 a pressure sensitive adhesive comprising:
 the cured reaction product of at least one X-A-B-A-X reactive oligomer, wherein X comprises an ethylenically unsaturated group, B comprises a non-silicone unit with a number average molecular weight of 5,000 grams/mole or greater, and A comprises a urethane linking group, wherein the adhesive is self wetting and removable; and 
   a substrate.   
     
     
         14 . The adhesive article of  claim 13 , wherein the substrate is a tape backing, a film, a sheet, or a release liner. 
     
     
         15 . The adhesive article of  claim 14 , wherein adhesive is optically clear. 
     
     
         16 . The adhesive article of  claim 15 , wherein the substrate comprises a film wherein the film comprises an optically active film comprising a visible mirror film, a color mirror film, a solar reflective film, a diffusive film, an infrared reflective film, an ultraviolet reflective film, a brightness enhancement film, a dual brightness enhancement film, an absorptive polarizer film, an optically clear film, a tinted film, a privacy film, a light-collimating film, or an antireflective film. 
     
     
         17 . The adhesive article of  claim 13 , wherein B comprises an oxyalkylene group. 
     
     
         18 . The adhesive article of  claim 13 , further comprising a second substrate, wherein the second substrate comprises a rigid surface, a flexible surface, a tape backing, a film, a sheet, or a release liner. 
     
     
         19 . The adhesive article of  claim 13 , wherein the pressure sensitive adhesive further comprises at least one additive, wherein the additive comprises a pressure sensitive adhesive, a plasticizing agent, a tackifying agent or a mixture thereof. 
     
     
         20 . The adhesive article of  claim 19 , comprising 5-60 weight % of added pressure sensitive adhesive and 5-55 weight % plasticizer. 
     
     
         21 . The adhesive article of  claim 19 , wherein the plasticizer comprises isopropyl myristate or polypropylene glygol. 
     
     
         22 . The adhesive article of  claim 19 , wherein the added pressure sensitive adhesive comprises a (meth)acrylate pressure sensitive adhesive. 
     
     
         23 . The adhesive article of  claim 19 , wherein the added pressure sensitive adhesive comprises an acid-containing (meth)acrylate pressure sensitive adhesive.