EP0720143A1 - Absorbing material for acoustic waves - Google Patents

Absorbing material for acoustic waves Download PDF

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Publication number
EP0720143A1
EP0720143A1 EP95402932A EP95402932A EP0720143A1 EP 0720143 A1 EP0720143 A1 EP 0720143A1 EP 95402932 A EP95402932 A EP 95402932A EP 95402932 A EP95402932 A EP 95402932A EP 0720143 A1 EP0720143 A1 EP 0720143A1
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EP
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Prior art keywords
acid
composition
acids
derived
counterions
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EP95402932A
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German (de)
French (fr)
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EP0720143B1 (en
Inventor
Stanislas Galaj
Frédéric Héliodore
Vincent Dionnet
Pavel Lemarinier
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Alcatel Lucent SAS
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Alcatel SA
Alcatel Alsthom Compagnie Generale dElectricite
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    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/162—Selection of materials

Definitions

  • the present invention relates to the absorption of acoustic waves in the audible range, between 20 Hz and 20 kHz.
  • An object of the present invention is to define a material absorbing sound waves in the audible spectrum, which is as light and as compact as possible, and which is effective even in the low frequency region of the sound spectrum.
  • said structure material is a deformable porous material impregnated with said thixotric material.
  • At least some of said counterions carry hydroxyl groups allowing interactions by hydrogen bonds.
  • said macromolecule is an acid polymer, such as polyacrylic acids, polystyrenesulfonic acids and carboxycelluloses, the counterions being from organic bases such as ammonia, amino alcohols (mono, di, or triethanolamine) and quaternary ammonium bases.
  • said macromolecule is a basic polymer such as polyethyleneimine, the counterions being derived from acids chosen from the group formed in particular by carboxylic acids such as citric acid, propionic acid and sebacic acid, and sulfonic and phosphonic acids.
  • the material according to the invention is used either in the form of coatings or by impregnation in a porous body.
  • the materials which, according to the invention, constitute sound absorbers having properties which are extremely advantageous from the point of view of lightness and bulk, can be divided into three groups.
  • a first group consists of acid polymers, such as polyacrylic acid, combined with a base such as triethanolamine.
  • the matrix consists of a set of carboxy sites (of negative charges) distributed uniformly along the chains.
  • the counterions originating from triethanolamine have polar substituents which can give hydrogen bonds.
  • an external force such as a sound wave
  • the network of polyacrylic acid deforms and the counterions move to immobilize near the nearest negative charge as soon as the stress ceases (effect thixotropy, mechanical-electrical conversion).
  • the material of the invention makes it possible to combine two behaviors, one of the elastic type relating more particularly to the network of electric charges for low activation energy, the other of the thixotropic type, for the higher energy d 'activation (viscosity and electro-mechanical effect).
  • the single figure is a diagram showing as a function of the frequency F of the sound wave, expressed in Hz, the reflection coefficient R expressed in dB.
  • the dashed line curve corresponds to the absorption of sound by a porous material; the solid line curve corresponds to the absorption of sound by the same porous material impregnated with a material consisting of polyacrylic acid and of which only 10% of the acid sites are salified with triethanolamine.
  • the material of the invention can, as in the example illustrated, be used by impregnation in a porous material.
  • the counterions come from small organic molecules (mono or polyfunctional) comprising at least one basic site (amine) and optionally the substituents capable of forming the hydrogen bonds.
  • a second group of materials is constituted by a basic polymer such as polyethyleneimine, the counterions (mono or polyvalent) coming from small organic molecules (mono or polyfunctional) comprising at least one acid site [carboxy (COOH), sulfo ( SO 3 H), phosphono (PO 3 H)] and optionally substituents capable of forming hydrogen bonds (-OH, -SH, -NH 2 , -COOH, etc.).
  • a basic polymer such as polyethyleneimine
  • the counterions mono or polyvalent coming from small organic molecules (mono or polyfunctional) comprising at least one acid site [carboxy (COOH), sulfo ( SO 3 H), phosphono (PO 3 H)] and optionally substituents capable of forming hydrogen bonds (-OH, -SH, -NH 2 , -COOH, etc.).
  • the counterions can thus be derived from citric acid, propionic acid and glycolic acid, this list not being limiting.
  • the invention is not limited to the materials described but applies to all materials meeting the general definition given.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

Absorbing compsn. for sound waves comprising: (a) a structural material (I) imparting limited rigidity to the compsn.; and (b) an absorbing material (II) having a lesser rigidity than the compsn. in order to dissipate the sound wave energy; is characterised in that (I) is a thixotropic material constituted by macromolecules (III) carrying electric charges of a same sign and having no mutual covalent bonds, the electric charges being neutralised by small and mobile counter ions. Pref. (I) is a plastic porous material impregnated with the thixotropic material. At least part of the counter ions carry hydroxyl groups allowing hydrogen bonding. (III) is (i) an acid polymer, such as polyacrylic acid, polystyrenesulphonic acid and carboxycellulose, the counter ions being derived from organic bases, such as ammonia, aminoalcohols (mono-, di- or tri-ethanol amine) and quat. ammoniums; or (ii) a basic polymer, such as polyethylene-imine, the counter ions being derived from carboxylic acids, such as citric acid, propionic acid, glycolic acid and sebacic acid, sulphonic acids or phosphonic acids.

Description

La présente invention est relative à l'absorption des ondes acoustiques dans la gamme audible, comprise entre 20 Hz et 20kHz.The present invention relates to the absorption of acoustic waves in the audible range, between 20 Hz and 20 kHz.

D'une manière générale, les matériaux absorbant les ondes acoustiques peuvent se classer, en première approximation, en deux catégories, suivant les modes d'absorption considérés:

  • la résonance, mettant en oeuvre le couple masse-élasticité d'un oscillateur harmonique,
  • la dissipation par effets thermique et de viscosité, qu'on rencontre par exemple dans les matériaux poreux.
In general, the materials absorbing acoustic waves can be classified, as a first approximation, into two categories, depending on the absorption modes considered:
  • resonance, using the mass-elasticity couple of a harmonic oscillator,
  • dissipation by thermal and viscosity effects, which is encountered, for example, in porous materials.

C'est de cette seconde classe de matériau qu'il est question.This second class of material is in question.

Un but de la présente invention est de définir un matériau absorbant les ondes sonores dans le spectre audible, qui soit aussi léger et aussi peu encombrant que possible, et qui soit efficace même dans la zone des basses fréquences du spectre sonore.An object of the present invention is to define a material absorbing sound waves in the audible spectrum, which is as light and as compact as possible, and which is effective even in the low frequency region of the sound spectrum.

L'invention a pour objet une composition absorbante pour ondes sonores, cette composition comportant :

  • un matériau de structure conférant une rigidité limitée à ladite composition, et
  • un matériau absorbant présentant par lui-même une rigidité plus faible que ladite composition pour dissiper l'énergie d'ondes sonores se propageant dans cette composition, ladite composition étant caractérisée par le fait que ledit matériau absorbant est un matériau thixotropique constitué de macromolécules porteuses de charges électriques d'un même signe et dépourvues de liaisons covalentes mutuelles, ces charges électriques étant neutralisées par des contre-ions mobiles et de petite taille.
The subject of the invention is an absorbent composition for sound waves, this composition comprising:
  • a structural material giving a limited rigidity to said composition, and
  • an absorbent material having by itself a lower rigidity than said composition for dissipating the energy of sound waves propagating in this composition, said composition being characterized in that said absorbent material is a thixotropic material consisting of macromolecules carrying electric charges of the same sign and devoid of mutual covalent bonds, these electric charges being neutralized by small and mobile counterions.

De préférence ledit matériau de struture est un matériau poreux déformable imprégné par ledit matériau thixotrique.Preferably said structure material is a deformable porous material impregnated with said thixotric material.

De préférence encore certains au moins desdits contre-ions sont porteurs de groupements hydroxyles permettant des interactions par liaisons hydrogène.More preferably still, at least some of said counterions carry hydroxyl groups allowing interactions by hydrogen bonds.

Dans un premier groupe de matériaux selon l'invention, ladite macromolécule est un polymère acide, tel que les acides polyacryliques, les acides polystyrènesulfoniques et les carboxycelluloses, les contre-ions étant issus de bases organiques telles que l'ammoniac, les amino-alcools (mono, di, ou triéthanolamine) et les bases ammonium quaternaires.In a first group of materials according to the invention, said macromolecule is an acid polymer, such as polyacrylic acids, polystyrenesulfonic acids and carboxycelluloses, the counterions being from organic bases such as ammonia, amino alcohols (mono, di, or triethanolamine) and quaternary ammonium bases.

Dans un second groupe de matériaux selon l'invention, ladite macromolécule est un polymère basique tel que le polyéthylène-imine, les contre-ions étant issus d'acides choisis dans le groupe formé notamment par les acides carboxyliques tels que l'acide citrique, l'acide propionique et l'acide sébacique, et les acides sulfoniques et phosphoniques.In a second group of materials according to the invention, said macromolecule is a basic polymer such as polyethyleneimine, the counterions being derived from acids chosen from the group formed in particular by carboxylic acids such as citric acid, propionic acid and sebacic acid, and sulfonic and phosphonic acids.

Le matériau selon l'invention est mis en oeuvre soit sous forme de revêtements, soit par imprégnation dans un corps poreux.The material according to the invention is used either in the form of coatings or by impregnation in a porous body.

L'invention est explicitée par divers exemples de réalisation du matériau absorbant selon l'invention, et on se référera au dessin annexé dans lequel la figure unique est un diagramme montrant l'absorption sonore d'un corps poreux seul et celle du même corps poreux imprégné d'un matériau selon l'invention.The invention is explained by various embodiments of the absorbent material according to the invention, and reference is made to the appended drawing in which the single figure is a diagram showing the sound absorption of a single porous body and that of the same porous body. impregnated with a material according to the invention.

Les matériaux qui, selon l'invention, constituent des absorbants sonores ayant des propriétés extrêmement intéressantes du point de vue de la légèreté et de l'encombrement, peuvent être divisées en trois groupes.The materials which, according to the invention, constitute sound absorbers having properties which are extremely advantageous from the point of view of lightness and bulk, can be divided into three groups.

Un premier groupe est constitué de polymères acides, tels que l'acide polyacrylique, combiné à une base telle que la triéthanolamine. Dans cet exemple, la matrice est constituée d'un ensemble de sites carboxy (de charges négatives) répartis uniformément le long des chaînes. Les contre-ions issus de la triéthanolamine (à charge unique positive) possèdent des substituants polaires pouvant donner des liaisons hydrogènes. Sous l'effet d'une force extérieure telle qu'une onde sonore, le réseau d'acide polyacrylique se déforme et les contre-ions se déplacent pour s'immobiliser près de la charge négative la plus proche dès que la contrainte cesse (effet de thixotropie, conversion mécanique-électrique). Le mouvement des contre-ions porteurs de groupements OH (par exemple groupements alcools non ionisés de type -(CH2)x-OH) va entraîner une réorganisation du réseau de liaisons hydrogène (élongation, rupture, formation), conduisant à une dissipation de type visqueux.A first group consists of acid polymers, such as polyacrylic acid, combined with a base such as triethanolamine. In this example, the matrix consists of a set of carboxy sites (of negative charges) distributed uniformly along the chains. The counterions originating from triethanolamine (with a single positive charge) have polar substituents which can give hydrogen bonds. Under the effect of an external force such as a sound wave, the network of polyacrylic acid deforms and the counterions move to immobilize near the nearest negative charge as soon as the stress ceases (effect thixotropy, mechanical-electrical conversion). The movement of counterions carrying OH groups (for example non-ionized alcohol groups of the - (CH 2 ) x -OH type) will cause a reorganization of the hydrogen bonding network (elongation, rupture, formation), leading to a dissipation of viscous type.

On voit que le matériau de l'invention permet de combiner deux comportements, l'un de type élastique concernant plus particulièrement le réseau de charges électriques pour de faibles énergie d'activation, l'autre de type thixotropique, pour les plus fortes énergies d'activation (viscosité et effet électro-mécanique).It can be seen that the material of the invention makes it possible to combine two behaviors, one of the elastic type relating more particularly to the network of electric charges for low activation energy, the other of the thixotropic type, for the higher energy d 'activation (viscosity and electro-mechanical effect).

La figure unique est un diagramme montrant en fonction de la fréquence F de l'onde sonore, exprimée en Hz, le coefficient de réflexion R exprimé en dB. La courbe en trait tireté correspond à l'absorption du son par un matériau poreux; la courbe en trait plein correspond à l'absorption du son par le même matériau poreux imprégné d'un matériau constitué d'acide polyacrylique et dont seulement 10% des sites acides sont salifiés par de la triéthanolamine. On observe un remarquable pic d'absorption centré sur 1150Hz et une très bonne atténuation entre 0 et 2000 Hz.The single figure is a diagram showing as a function of the frequency F of the sound wave, expressed in Hz, the reflection coefficient R expressed in dB. The dashed line curve corresponds to the absorption of sound by a porous material; the solid line curve corresponds to the absorption of sound by the same porous material impregnated with a material consisting of polyacrylic acid and of which only 10% of the acid sites are salified with triethanolamine. There is a remarkable absorption peak centered on 1150Hz and a very good attenuation between 0 and 2000 Hz.

Le matériau de l'invention peut, comme dans l'exemple illustré, être mis en oeuvre par imprégnation dans un matériau poreux.The material of the invention can, as in the example illustrated, be used by impregnation in a porous material.

Dans le premier groupe des matériaux de l'invention, on trouve, comme polymères acides, outre l'acide polyacrylique, les acides polystyrènesulfoniques et les carboxycelluloses; cette liste n'est pas limitative.In the first group of materials of the invention, there are, as acid polymers, in addition to polyacrylic acid, polystyrenesulfonic acids and carboxycelluloses; this list is not exhaustive.

Les contre-ions (mono ou polyvalents) sont issus de petites molécules organiques (mono ou polyfonctionnelles) comprenant au moins un site basique (amine) et éventuellement les substituants capables de former les liaisons hydrogène.The counterions (mono or polyvalent) come from small organic molecules (mono or polyfunctional) comprising at least one basic site (amine) and optionally the substituents capable of forming the hydrogen bonds.

On rencontre ainsi comme fournisseurs de contre-ions, non seulement la triéthanolamine, mais aussi les autres éthanolamines (mono et di), l'ammoniac et les bases ammonium quaternaires, cette liste n'étant, là encore, non limitative.We thus meet as suppliers of counterions, not only triethanolamine, but also the other ethanolamines (mono and di), ammonia and quaternary ammonium bases, this list being, here again, not limiting.

A titre d'exemple on peut citer:

  • NH 4 + : ion ammonium issu de l'ammoniac
  • NH 3 + - (CH 2 ) 12 -NH 3 + : ion dodécaméthylènebis (ammonium) issu du 1,12-diaminododécane
  • NH 3 + -CH 2 -CH 2 -OH: ion 2-hydroxyéthylammonium issu de la monoéthanolamine
  • NH + (CH 2 -CH 2 -OH) 3 : ion tris(2-hydroxyéthyl)ammonium issu de la triéthanolamine
  • N + (CH 2 -CH 2 -CH 2 -CH 3 ) 4 : ion tétrabutylammonium issu du tétrabutylammonium hydroxyde
  • NH 3 + -CH 2 -COOH: ion carboxyméthylammonium issu de la glycine.
By way of example, we can cite:
  • NH 4 + : ammonium ion derived from ammonia
  • NH 3 + - (CH 2 ) 12 -NH 3 + : dodecamethylenebis (ammonium) ion derived from 1,12-diaminododecane
  • NH 3 + -CH 2 -CH 2 -OH : 2-hydroxyethylammonium ion derived from monoethanolamine
  • NH + (CH 2 -CH 2 -OH) 3 : tris (2-hydroxyethyl) ammonium ion from triethanolamine
  • N + (CH 2 -CH 2 -CH 2 -CH 3 ) 4 : tetrabutylammonium ion derived from tetrabutylammonium hydroxide
  • NH 3 + -CH 2 -COOH : carboxymethylammonium ion derived from glycine.

A titre d'exemple, les substituants capable de former des liaisons hydrogène peuvent être:

  • OH   (hydroxy)
  • SH   (sulfhydryl)
  • NH 2    (amino)
  • COOH   (carboxy)
By way of example, the substituents capable of forming hydrogen bonds can be:
  • OH (hydroxy)
  • SH (sulfhydryl)
  • NH 2 (amino)
  • COOH (carboxy)

Un second groupe de matériaux est constitué par un polymère basique tel que le polyéthylèneimine, les contre-ions (mono ou polyvalents) étant issus de petites molécules organiques (mono ou polyfonctionnelles) comprenant au moins un site acide [carboxy (COOH), sulfo (SO3H), phosphono (PO3H)] et éventuellement des substituants capables de former des liaisons hydrogène (-OH, -SH, -NH2, -COOH, etc...).A second group of materials is constituted by a basic polymer such as polyethyleneimine, the counterions (mono or polyvalent) coming from small organic molecules (mono or polyfunctional) comprising at least one acid site [carboxy (COOH), sulfo ( SO 3 H), phosphono (PO 3 H)] and optionally substituents capable of forming hydrogen bonds (-OH, -SH, -NH 2 , -COOH, etc.).

Les contre-ions peuvent ainsi être issus de l'acide citrique, de l'acide propionique et de l'acide glycolique cette liste n'étant pas limitative.The counterions can thus be derived from citric acid, propionic acid and glycolic acid, this list not being limiting.

A titre d'exemple, on peut citer les contre-ions suivants:

  • CH 3 -CH 2 -COO - : ion propionate issu de l'acide propionique
  • - O-CO(CH 2 ) 8 -COO - : ion octaméthylènebis (carboxylate) issu de l'acide sébacique
  • HO-CH 2 -COO - : ion hydroxyacétate provenant de l'acide glycolique
  • HO-CO-C(OH)(CH 2 -COO - ) 2 : ion citrate provenant de l'acide citrique
  • HO-(CH 2 ) 4 -SO 3 - : ion 4-hydroxy-1-butanesulfonium provenant de l'acide 4-hydroxy-1-butanesulfonique
  • CH 3 -(CH 2 ) 3 -PO 3 - : ion n-butanephosphonium provenant de l'acide n-butanephosphonique
By way of example, the following counterions can be cited:
  • CH 3 -CH 2 -COO - : propionate ion derived from propionic acid
  • - O-CO (CH 2 ) 8 -COO - : octamethylene bis (carboxylate) ion derived from sebacic acid
  • HO-CH 2 -COO - : hydroxyacetate ion from glycolic acid
  • HO-CO-C (OH) (CH 2 -COO - ) 2 : citrate ion from citric acid
  • HO- (CH 2 ) 4 -SO 3 - : 4-hydroxy-1-butanesulfonium ion from 4-hydroxy-1-butanesulfonic acid
  • CH 3 - (CH 2 ) 3 -PO 3 - : n-butanephosphonium ion from n-butanephosphonic acid

On retrouve dans ces matériaux la double fonction d'atténuation des ondes sonores par thixotropie et par dissipation visqueuse.These materials have the dual function of attenuating sound waves by thixotropy and by viscous dissipation.

L'invention n'est pas limitée aux matériaux décrits mais s'applique à tous les matériaux répondant à la définition générale donnée.The invention is not limited to the materials described but applies to all materials meeting the general definition given.

Claims (5)

Composition absorbante pour ondes sonores, cette composition comportant : - un matériau de structure conférant une rigidité limitée à ladite composition, et - un matériau absorbant présentant par lui-même une rigidité plus faible que ladite composition pour dissiper l'énergie d'ondes sonores se propageant dans cette composition, ladite composition étant caractérisée par le fait que ledit matériau absorbant est un matériau thixotropique constitué de macromolécules porteuses de charges électriques d'un même signe et dépourvues de liaisons covalentes mutuelles, ces charges électriques étant neutralisées par des contre-ions mobiles et de petite taille. Absorbent composition for sound waves, this composition comprising: a structural material which confers a rigidity limited to said composition, and an absorbent material having by itself a lower rigidity than said composition for dissipating the energy of sound waves propagating in this composition, said composition being characterized in that said absorbent material is a thixotropic material consisting of carrier macromolecules electric charges of the same sign and devoid of mutual covalent bonds, these electric charges being neutralized by mobile counter-ions and of small size. Composition selon la revendication 1, caractérisée par le fait que ledit matériau de struture est un matériau poreux déformable imprégné par ledit matériau thixotrique.Composition according to Claim 1, characterized in that the said structure material is a deformable porous material impregnated with the said thixotric material. Composition selon la revendication 1, caractérisée par le fait que certains au moins desdits contre-ions sont porteurs de groupements hydroxyles permettant des interactions par liaisons hydrogène.Composition according to Claim 1, characterized in that at least some of the said counterions carry hydroxyl groups allowing interactions by hydrogen bonds. Composition selon la revendication 1, caractérisée par le fait que ladite macromolécule est un polymère acide, tel que les acides polyacryliques, les acides polystyrènesulfoniques et les carboxycelluloses, les contre-ions étant issus de bases organiques telles que l'ammoniac, les amino-alcools (mono, di, ou triéthanolamine) et les bases ammonium quaternaires.Composition according to Claim 1, characterized in that the said macromolecule is an acid polymer, such as polyacrylic acids, polystyrenesulfonic acids and carboxycelluloses, the counterions being derived from organic bases such as ammonia, amino alcohols (mono, di, or triethanolamine) and quaternary ammonium bases. Composition selon la revendication 1, caractérisée par le fait que ladite macromolécule est un polymère basique tel que le polyéthylène-imine, les contre-ions étant issus d'acides choisis notamment dans le groupe formé par les acides carboxyliques tels que l'acide citrique, l'acide propionique, l'acide glycolique et l'acide sébacique, et les acides sulfoniques et phosphoniques.Composition according to Claim 1, characterized in that the said macromolecule is a basic polymer such as polyethyleneimine, the counterions being derived from acids chosen in particular from the group formed by carboxylic acids such as citric acid, propionic acid, glycolic acid and sebacic acid, and sulfonic and phosphonic acids.
EP19950402932 1994-12-26 1995-12-22 Absorbing material for acoustic waves Expired - Lifetime EP0720143B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9415646A FR2728715B1 (en) 1994-12-26 1994-12-26 ACOUSTIC WAVE ABSORBING MATERIAL
FR9415646 1994-12-26

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EP0720143A1 true EP0720143A1 (en) 1996-07-03
EP0720143B1 EP0720143B1 (en) 2000-09-06

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3843576A (en) * 1972-09-20 1974-10-22 United States Steel Corp Aqueous coating compositions of ethylene/acrylic acid copolymer and phenolic resin
US4374172A (en) * 1977-12-19 1983-02-15 Teroson Gmbh Sound insulating material
JPS61268439A (en) * 1985-05-22 1986-11-27 三菱油化株式会社 Composite steel plate for damping vibration
DE3708961A1 (en) * 1987-03-22 1988-10-13 Pelzer Helmut Multifunctional insulation system for oscillating surfaces
EP0360037A2 (en) * 1988-09-19 1990-03-28 Siemens Aktiengesellschaft Damping mass for SW elements
JPH06210800A (en) * 1993-01-20 1994-08-02 Nippon Carbide Ind Co Inc Damping thin material
EP0653464A2 (en) * 1993-11-17 1995-05-17 Bridgestone Corporation A polymer composition having a low modulus and a process for producing the same

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3843576A (en) * 1972-09-20 1974-10-22 United States Steel Corp Aqueous coating compositions of ethylene/acrylic acid copolymer and phenolic resin
US4374172A (en) * 1977-12-19 1983-02-15 Teroson Gmbh Sound insulating material
JPS61268439A (en) * 1985-05-22 1986-11-27 三菱油化株式会社 Composite steel plate for damping vibration
DE3708961A1 (en) * 1987-03-22 1988-10-13 Pelzer Helmut Multifunctional insulation system for oscillating surfaces
EP0360037A2 (en) * 1988-09-19 1990-03-28 Siemens Aktiengesellschaft Damping mass for SW elements
JPH06210800A (en) * 1993-01-20 1994-08-02 Nippon Carbide Ind Co Inc Damping thin material
EP0653464A2 (en) * 1993-11-17 1995-05-17 Bridgestone Corporation A polymer composition having a low modulus and a process for producing the same

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Section Ch Week 8702, Derwent World Patents Index; Class A88, AN 87-010871 *
PATENT ABSTRACTS OF JAPAN vol. 018, no. 572 (M - 1696) 2 November 1994 (1994-11-02) *

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Publication number Publication date
EP0720143B1 (en) 2000-09-06
DE69518730D1 (en) 2000-10-12
FR2728715B1 (en) 1997-01-31
FR2728715A1 (en) 1996-06-28

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