US 4,447,493 AGranted

Vibration-damping constrained-layer constructions

AssigneeMinnesota Mining and Manufacturing Company

InventorsWilliam A. Driscoll, Steven M. Heilmann, Jerald K. Rasmussen

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Abstract

A constrained-layer construction comprising a stiff layer or substrate and a layer of a viscoelastic polymer which is the reaction product of (a) 25 to 75 weight percent of an acryloyl or methacryloyl derivative of at least one oligomer, said oligomer having a glass transition temperature of less than 25.degree. C. and a molecular weight per oligomer of 600 to 20,000, and (b) 75 to 25 weight percent of a copolymerizable monomer whose homopolymer has a glass transition temperature of at least 50.degree. C., the copolymer being suitable for damping vibrations at relatively high temperatures, e.g., 50.degree.-150.degree. C., is disclosed. Also included is a process for damping vibrations in component parts of devices used in automotive, aerospace, and computer industries.

Claims8

Dependent claims

A constrained-layer construction for damping vibrations in solid articles at a temperature of at least 50.degree. C., said construction comprising a substrate having a stiffness relative to stainles steel of at least 0.40 and bearing a continuous layer of a copolymer having a thickness of 0.01 mm to 100 mm, said copolymer having a storage modulus of at least 1.times.10.sup.7 dynes/cm.sup.2 and a loss tangent above 0.5 at 100.degree. C. and 1000 Hz, said copolymer being the reaction product of a mixture comprising:

(a) 25 to 75 weight percent of an acryloyl or methacryloyl derivative of at least one oligomer, said oligomer having a glass transition temperature of less than 25.degree. C. and a molecular weight per oligomer of 600 to 20,000, said oligomer having the formula ##STR9##
wherein:
R is the organic residue of a nucleophilic group-substituted oligomer having a molecular weight of 600 to 20,000, glass transition temperature of less than 25.degree. C., and n hydroxyl, amino or thiol groups, said nucleophilic group-substituted oligomer being selected from the group consisting of polyoxyalkylene, poly(perfluorooxyalkylene), polyester, polyolefin, polyacrylate, polyamide, and polysiloxane oligomers;
n is the valence of R having a value of at least one;
Y is selected from --O--, --S-- and ##STR10## in which R.sup.2 is (a) hydrogen, or (b) a hydrocarbyl group selected from (1) an alkyl or cycloalkyl group having 1 to 12 carbon atoms optionally substituted by cyano, hydrogen or alkoxy group having 1 to 4 carbon atoms, or (2) an aryl or aralkyl group having 6 to 12 carbon atoms;
X is a divalent connecting group;
and
R.sup.1 is hydrogen or methyl;
and
(b) 75 to 25 weight percent of a copolymerizable monomer whose homopolymer has a glass transition temperature of at least 50.degree. C.

7 more elements

A process for damping the vibration of a vibrating solid article at temperatures above 50.degree. C., said process comprising the steps:

(a) providing a constrained-layer construction, said construction comprising at least one substrate having a stiffness relative to stainles steel of at least 0.40 coated with at least one continuous layer of a viscoelastic copolymer having a thickness of 0.01 mm to 100 mm, said copolymer having a storage modulus of at least 1.times.10.sup.7 dynes/cm.sup.2 and a loss tangent above 0.5 to 100.degree. C. and 1000 Hz, said copolymer being the reaction product of a mixture comprising:
(1) 25 to 75 percent of an acryloylated or methacryloylated oligomer having a glass transition temperature of less than 25.degree. C. and a molecular weight of 600 to 20,000, said oligomer having the formula ##STR11## wherein:
R is the organic residue of a nucelophilic group-substituted oligomer having a molecular weight of 600 to 20,000, glass transition temperature of less than 25.degree. C., and n hydroxyl, amino or thiol groups, said nucleophilic group-substituted oligomer being selected from the group consisting of polyoxyalkylene, poly(perfluorooxyalkylene), polyester, polyolefin, polyacrylate, polyamide, and polysiloxane oligomers;
n is the valence of R having a value of at least one;
Y is selected from --O--, --S-- and ##STR12## in which R.sup.2 is (a) hydrogen, or (b) a hydrocarbyl group selected from (1) an alkyl or cycloalkyl group having 1 to 12 carbon atoms optionally substituted by cyano, hydrogen or alkoxy group having 1 to 4 carbon atoms, or (2) an aryl or aralkyl group having 6 to 12 carbon atoms;
X is a divalent connecting group;
and
R.sup.1 is hydrogen or methyl;
and
(2) 75 to 25 percent by weight of a copolymerizable monomer whose homopolymer has a glass transition temperature of at least 50.degree. C., and
(3) an effective amount of a free-radical generator, and
(b) affixing said constrained-layer construction onto said solid article.

9 more elements

Dependencies are inferred from the claim text.