Pressure sensitive adhesive assembly comprising filler material

1. A multilayer pressure sensitive adhesive assembly comprising:

a first pressure sensitive adhesive layer comprising a hollow non-porous particulate filler material, wherein the surface of the hollow non-porous particulate filler material is provided with a hydrophobic surface modification by chemically reacting said non-porous particulate filler material with an alkoxy silane subjected to a partial or total hydrolysis treatment, the alkoxy silane having the following formula:

(R 1 O) m—Si—(R 2 ) 4-m

wherein R 1 is an alkyl group comprising 1 to 6 carbon atoms, m=1 to 3, and R 2 is a hydrophobic moiety selected from the group consisting of saturated, unsaturated, substituted or un-substituted alkyls, ethers, thioethers, esters, amides, amines, carbamates, urethanes, polyolefins, and any combinations thereof;

wherein the hollow non-porous particulate filler material consists of hollow glass microspheres, and wherein the first pressure sensitive adhesive layer is a polymeric foam layer and having a thickness in a range of 100 to 6000 micrometers, the first pressure sensitive adhesive layer comprising a polymer base material comprised of a polar acrylate comonomer; and

a second pressure sensitive adhesive layer adjacent to and separate from the first pressure sensitive adhesive layer, wherein the second pressure sensitive adhesive layer is an unfoamed skin layer that does not contain any hollow non-porous particulate filler material and has a thickness in a range of 20 to 250 micrometers,

wherein the hollow non-porous particulate filler material provided with a hydrophobic surface modification leads to increased debonding between the polymer base material and the surface of the hollow non-porous particulate filler material.

2. A multilayer pressure sensitive adhesive assembly according to claim 1 , wherein the hydrophobic surface modification of the hollow non-porous particulate filler material is performed with alkyl groups through covalent bonds, preferably through covalent siloxane bonds, between the alkyl groups and the surface of the hollow non-porous particulate filler material.

3. A multilayer pressure sensitive adhesive assembly according to claim 1 , wherein the alkoxy silane has the following formula:

(R 1 O) m—Si—(R 2 ) 4-m

wherein:

R 1 is selected from the group consisting of methyl and ethyl;

m=2 or 3 R 2 is independently selected from the group consisting of methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, and fluorinated derivatives thereof, tridecafluroro-1,2,2,2-tetrahydrooctyl.

4. A multilayer pressure sensitive adhesive assembly according to claim 3 , wherein the surface of the hollow non-porous particulate filler material is pre-treated with hydrogen peroxide prior to being provided with a hydrophobic surface modification.

5. A multilayer pressure sensitive adhesive assembly according claim 1 , wherein the hydrophobic surface modification of the hollow non-porous particulate filler material is performed by applying a hydrophobic coating.

6. A multilayer pressure sensitive adhesive assembly according to claim 5 , wherein the hydrophobic coating is applied by contacting the hollow non-porous particulate filler material with a liquid medium selected from the group of emulsions, suspensions or solutions, and comprising a component preferably selected from the group consisting of alkoxy silanes, hydrocarbon waxes, polyethylene waxes, fluorinated hydrocarbon waxes, silicone, and any combinations or mixtures thereof.

7. A multilayer pressure sensitive adhesive assembly according to claim 1 , which is in the form of a skin/core multilayer pressure sensitive adhesive assembly, wherein the first pressure sensitive adhesive layer is the core layer of the multilayer pressure sensitive adhesive assembly and the second pressure sensitive adhesive layer is the skin layer of the multilayer pressure sensitive adhesive assembly.

8. A multilayer pressure sensitive adhesive assembly according claim 1 , wherein the first pressure sensitive adhesive layer and/or the second pressure sensitive adhesive layer comprises a polymer base material selected from the group consisting of polyacrylates, polyurethanes, polyolefins, polyamines, polyamides, polyesters, polyethers, polyisobutylene, polystyrenes, polyvinyls, polyvinylpyrrolidone, natural rubbers, synthetic rubbers, and any combinations, copolymers or mixtures thereof.

9. A multilayer pressure sensitive adhesive assembly according to claim 8 , wherein the first pressure sensitive adhesive layer and/or the second pressure sensitive adhesive layer a polymer base material selected from the group consisting of polyacrylates whose main monomer component preferably comprises a linear or branched alkyl (meth)acrylate ester, preferably a non-polar linear or branched alkyl (meth)acrylate ester having a linear or branched alkyl group comprising preferably from 1 to 32, from 1 to 20, or even from 1 to 15 carbon atoms.

10. The multilayer pressure sensitive adhesive assembly of claim 1 , wherein the polar acrylate comonomer comprises acrylic acid, methacrylic acid, itaconic acid, hydroxyalkyl acrylate, acrylamide, substituted acrylamide, acrylamine, substituted acrylamine, acrylonitrile, methacrylonitrile, hydroxyalkyl acrylate, cyanoethyl acrylate, maleic anhydride, N-vinyl-2-pyrrolidone, N-vinyl-caprolactam, or a combination or mixture thereof.