Pressure-sensitive adhesive tape containing hydrophobic silica
AssigneeMinnesota Mining and Manufacturing Company
InventorsJurgen Klingen, Patrick G. Zimmerman
Life of this patent
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Abstract
By incorporating hydrophobic silica into acrylic pressure-sensitive adhesive tape, the shear strength at elevated temperatures is significantly improved, and adhesion and physical properties are maintained or improved. The hydrophobic silica preferably has a surface area from 50 to 400 m.sup.2 /g. A preferred acrylic pressure-sensitive adhesive layer comprises a copolymer of (a) at least one alkyl acrylate having an average of 4-12 carbon atoms in its alkyl group and (b) from 3 to 20% by weight of copolymerizable monomer having a polar group such as acrylic acid.
Claims8
Pressure-sensitive adhesive tape, the adhesive layer which comprises a copolymer of by weight (a) a major proportion of acrylic acid ester of notertiary alkyl alcohol, the molecules of which have from 1 to 14 carbon atoms, at least a major proportion of said molecules having a carbon-to-carbon chain of 4-12 carbon atoms terminating at the hydroxyl oxygen atom, said chain containing at least about one-half the total number of carbon atoms in the molecule, and (b) a minor proportion of at least one copolymerizable monomer having a polar group, wherein the improvement comprises:
- the pressure-sensitive adhesive layer includes hydrophobic silica having a surface area of at least 10 m.sup.2 /g and in an amount comprising by weight from 2 to 15 phr.
Pressure-sensitive adhesive tape, the adhesive layer which comprises a copolymer of by weight (a) a major proportion of acrylic acid ester of nontertiary alkyl alcohol, the molecules of which have from 1 to 14 carbon atoms, at least a major proportion of said molecules having a carbon-to-carbon chain of 4 to 14 carbon atoms terminating at the hydroxyl oxygen atom, said chain containing at least about one-half of the total number of carbon atoms in the molecule, and (b) a minor proportion of at least one copolymerizable monomer having a polar group, wherein the improvement comprises:
- the pressure-sensitive adhesive layer includes hydrophobic silica in an amount providing good adhesion and physical properties and a Static Shear Value at 70.degree. C. (as herein defined) of at least 2000 minutes.
Dependencies are inferred from the claim text.