Adhesive compositions, adhesive articles and methods for making the same

Abstract

Adhesive compositions comprising a high molecular weight acrylic copolymer and a low molecular weight copolymer are disclosed. Adhesive articles and methods of making adhesive compositions and articles are also described.

1 - 28 . (canceled) 
   
   
       29 . An adhesive composition comprising a blend of:
 (i) a first acrylic copolymer resulting from polymerization of one or more monomers A and one or more monomers B, wherein the first acrylic copolymer has a number average molecular weight, M n , ranging from about 150,000 to about 600,000; and   (ii) a second acrylic copolymer resulting from polymerization of one or more monomers C and one or more monomers D, wherein the second acrylic copolymer has a number average molecular weight, M n , ranging from about 10,000 to about 70,000;   wherein monomers B and monomers D have at least one reactive group that is capable of hydrogen bonding; the second acrylic copolymer comprises greater than about 10 total parts by weight of the monomers D based a total weight of the second acrylic copolymer; and the total parts by weight of the monomers D in the second acrylic copolymer is greater than the total parts by weight of the monomers B in the first acrylic copolymer.   
   
   
       30 . The adhesive composition of  claim 29 , wherein the amount of the first acrylic copolymer present in the composition is greater than the amount of the second acrylic copolymer present in the composition. 
   
   
       31 . The adhesive composition of  claim 30 , wherein the first acrylic copolymer is present in an amount ranging from about 75 to about 98 parts by weight, and the second acrylic copolymer is present in an amount ranging from about 25 to about 2 parts by weight, based on a total weight of the first acrylic copolymer and the second acrylic copolymer. 
   
   
       32 . The adhesive composition of  claim 29 , wherein the total parts by weight of monomers D in the second acrylic copolymer is at least about 3 parts by weight greater than the total parts by weight of monomers B in the first acrylic copolymer. 
   
   
       33 . The adhesive composition of  claim 29 , wherein the first acrylic copolymer comprises from about 2 to about 10 total parts by weight of monomers B based on a total weight of the first acrylic copolymer, and the second acrylic copolymer comprises from bout 10 to about 25 total parts by weight of monomers D based on a total weight of the second acrylic copolymer. 
   
   
       34 . The adhesive composition of  claim 29 , wherein the monomers A and C are each independently selected from the group consisting of methyl acrylate, ethyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, isooctyl acrylate, octadecyl acrylate, nonyl acrylate, decyl acrylate, dodecyl acrylate, benzyl acrylate, cyclobenzyl acrylate, phenyl acrylate, any corresponding methacrylate thereof, and combinations thereof. 
   
   
       35 . The adhesive composition of  claim 29 , wherein the monomers B and D are each independently selected from the group consisting of acrylic acid, methacrylic acid, beta-carboxy ethyl acrylate, itaconic acid, neodecanoic acid, neononanoic acid, neopentanoic acid, 2-ethylhexanoic acid, propionic acid and combinations thereof. 
   
   
       36 . An adhesive article comprising a layer of the adhesive composition of claim  1 , wherein the adhesive composition has been cured. 
   
   
       37 . The adhesive article of  claim 36 , wherein the adhesive composition has a stress relaxation ratio G(300)/G(0.1) as measured by a Stress Relaxation Test at 70° C. of from about 0.10 to about 0.30 after exposure to electron beam radiation. 
   
   
       38 . The adhesive article of  claim 36 , wherein the adhesive article passes a static shear test by maintaining a hanging load of 500 g for at least 10,000 minutes at 70° C. 
   
   
       39 . The adhesive article of  claim 36 , wherein the layer of the adhesive composition is a foam layer. 
   
   
       40 . The adhesive article of  claim 39 , wherein the adhesive article has a density of from about 0.30 g/cc to about 0.80 g/cc. 
   
   
       41 . The adhesive article of  claim 39 , wherein the foam layer comprises microspheres. 
   
   
       42 . The adhesive article of  claim 36 , further comprising a first adhesive layer on a first outer surface of the layer of the adhesive composition and a second adhesive layer on a second outer surface of the layer of the adhesive composition opposite the first adhesive layer. 
   
   
       43 . The adhesive article of  claim 36 , further comprising a controlled degree of crosslinking between the first acrylic copolymer and the second acrylic copolymer. 
   
   
       44 . A method of making an adhesive article, said method comprising:
 providing an electron beam generating apparatus having a first control for an accelerating voltage and a second control for a dose;   providing a material to be cured having a composition, a thickness, and a density;   determining one or more desired properties capable of resulting from a controlled amount of crosslinking using the electron beam generating apparatus; and   using a Minimum Calculated Core Cure value of the material based on dose-depth profile calibration curves for the electron beam generating apparatus and for the material to be cured, crosslinking the material at a voltage and dose that results in the one or more desired properties.   
   
   
       45 . The method of  claim 44 , further comprising:
 preparing the dose-depth profile calibration curves for the electron beam generating apparatus and for the material to be cured based on the composition, thickness, and density of the material; and   determining the Minimum Calculated Core Cure value based on the dose-depth profile calibration curves.   
   
   
       46 . The method of  claim 44 , wherein the one or more desired properties comprise stress relaxation, shear strength, or a combination thereof. 
   
   
       47 . The method of  claim 44 , wherein the material after curing exhibits a cure gradient through a cross section of the thickness of the material. 
   
   
       48 . The method of  claim 44 , wherein the material comprises a blend of:
 (i) a first acrylic copolymer resulting from polymerization of one or more monomers A and one or more monomers B, wherein the first acrylic copolymer has a number average molecular weight, M n , ranging from about 150,000 to about 600,000; and   (ii) a second acrylic copolymer resulting from polymerization of one or more monomers C and one or more monomers D, wherein the second acrylic copolymer has a number average molecular weight, M n , ranging from about 10,000 to about 70,000;   wherein monomers B and monomers D have at least one reactive group that is capable of hydrogen bonding; the second acrylic copolymer comprises greater than about 10 total parts by weight of the monomers D based a total weight of the second acrylic copolymer; and the total parts by weight of the monomers D in the second acrylic copolymer is greater than the total parts by weight of the monomers B in the first acrylic copolymer.