Acoustic damping element with improved stackability
A vibration and noise damping element including a damping layer having first and second surfaces and an adhesive layer covering at least part of the first surface. The damping layer is composed of a damping layer material with a viscosity at 60° C. of 30′000-500′000 Pa*s containing at least one rubber component and the adhesive layer is composed of an adhesive layer material with a viscosity at 60° C. of 50′000-300′000 Pa*s containing at least one rubber component. The ratio of the thickness of the damping layer d 1 to the adhesive layer d 2 (d 1 /d 2 ) is 0.6-4.0 and the sum (d 1 +d 2 ) is 0.5-2.5 mm. The element shows good performance in the ball drop test at low temperatures, has good adhesion to the substrate it is applied to, provides good vibration and noise damping properties and guarantees easy separation after storage at temperatures between 30-50° C.
1 . A vibration and noise damping element comprising:
a damping layer having a first surface and a second surface; and
an adhesive layer covering at least a portion of the first surface of the damping layer, wherein:
the damping layer is composed of a damping layer material with a viscosity at 60° C. of 30′000-500′000 Pa*s containing at least one rubber component Ru;
the adhesive layer is composed of an adhesive layer material with a viscosity at 60° C. of 50′000-300′000 Pa*s containing the at least one rubber component Ru;
a ratio of a thickness of the damping layer d 1 to a thickness of the adhesive layer d 2 (d 1 /d 2 ) is 0.6-4.0;
a sum of the thickness of the damping layer d 1 and the thickness of the adhesive layer d 2 (d 1 +d 2 ) is 0.5-2.5 mm;
the viscosity is determined according to DIN 54458 oscillographically by means of a rheometer with a heatable plate measured at gap 500 μm, measuring plate diameter: 25 mm (plate/plate), deformation 1%, angular frequency 10 rad/s;
the adhesive layer comprises, based on a total weight of the adhesive laver:
1-15 wt.-% of at least one polybutadiene PB;
12.5-35 wt.-% of an at 25° C. liquid rubber LR;
4.5-15 wt-% of at least one natural polyisoprene or synthetic polyisoprene PI;
4.5-15 wt.-% of at least one butyl rubber BR;
5-12 wt.-% of at least one hydrocarbon resin HR; and
5-75 wt.-% of at least one solid particulate filler FM; and
the damping layer comprises, based on a total weight of the damping layer:
10-18 wt.-% of at least one at 25° C. liquid rubber LR;
2-5 wt.-% of at least one butyl rubber BR;
0.5-3 wt-% of at least one natural polyisoprene or synthetic polyisoprene PI;
5-10 wt.-% of at least one hydrocarbon resin HR; and
50-80 wt-% of at least one solid particulate filler FM.
2 . The vibration and noise damping element according to claim 1 , wherein the damping layer material has a viscosity at 60° C. of 40′000-250′000 Pa*s.
3 . The vibration and noise damping element according to claim 1 , wherein the adhesive layer material has a viscosity at 60° C. of 60′000-200′000 Pa*s.
4 . The vibration and noise damping element according to claim 1 , wherein the damping layer material is not identical to the adhesive layer material.
5 . The vibration and noise damping element according to claim 1 , wherein the ratio of the thickness of the damping layer d 1 to the thickness of the adhesive layer d 2 (d 1 /d 2 ) is 0.8-3.0.
6 . The vibration and noise damping element according to claim 1 , wherein the sum of the thickness of the damping layer d 1 and the thickness of the adhesive layer d 2 (d 1 +d 2 ) is 0.75-2.1 mm.
7 . The vibration and noise damping element according to claim 1 , wherein the damping layer material has a viscosity at 100° C. of 20′000-150′000 Pa*s.
8 . The vibration and noise damping element according to claim 1 , wherein the adhesive layer material has a viscosity at 100° C. of 60′000-200′000 Pa*s.
9 . The vibration and noise damping element according to claim 1 , wherein the thickness of the damping layer d 1 is 0.4-1.5 mm.
10 . The vibration and noise damping element according to claim 1 , wherein the thickness of the adhesive layer d 2 is 0.25-0.85 mm.
11 . The vibration and noise damping element according to claim 1 , wherein the adhesive layer material has an adhesion of ≤grade 3, determined by a ball drop test at −30° C. according to a Volkswagen group standard, quality requirements, self-adhesive stiffening pads and sound deadening pads, QP M052 page 12, point 3.7.5 Ball drop test/determination of cold adhesion (“Kugelfall/Bestimmung der Kältehaftung”), PV 3971, edition 2020-03, using test samples with a length/width/thickness of the adhesive layer material of 7 cm×7 cm×1.7 mm with an aluminum layer with a thickness of 0.3 mm on top of the adhesive layer material.
12 . The vibration and noise damping element according to claim 1 further comprising a constrained layer covering at least a portion of the second surface of the damping layer.
13 . The vibration and noise damping element according to claim 12 , wherein the damping layer and the constrained layer are directly connected to each other over their opposing surfaces.
14 . The vibration and noise damping element according to claim 12 , wherein the constrained layer is a metal sheet; and the thickness of the constrained layer d 3 is 0.05-0.6 mm.
15 . The vibration and noise damping element according to claim 1 , wherein the vibration and noise damping element has the following properties:
temperature at which a maximum loss factor is measured, T @LF max is between 5° C. or 25° C., and
value of the maximum loss factor, LF max , is ≥0.3, whereby a loss factor is determined by using a measurement method as defined in ISO 6721 standard.