U.S. patent application number 17/045674 was filed with the patent office on 2021-04-08 for anti-icing stack.
The applicant listed for this patent is 3M INNOVATIVE PROPERTIES COMPANY. Invention is credited to Frans A. Audenaert, Andrea Habbe, Michael Juergens, Bernd Kuhneweg, Christoph T. R. Schuell.
Application Number | 20210101361 17/045674 |
Document ID | / |
Family ID | 1000005324906 |
Filed Date | 2021-04-08 |
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United States Patent
Application |
20210101361 |
Kind Code |
A1 |
Kuhneweg; Bernd ; et
al. |
April 8, 2021 |
ANTI-ICING STACK
Abstract
Anti-icing stacks for protecting an aerodynamic surface are
described. In some embodiments, an anti-icing stack includes an
anti-icing layer, an elastomeric erosion protection layer, and an
additional layer. The erosion protection layer is disposed between
the anti-icing layer and the additional layer. The additional layer
has a thickness greater than the thickness of the erosion
protection layer and a tensile modulus of no more than the tensile
modulus of the erosion protection layer. The additional layer may
be a foam adhesive layer.
Inventors: |
Kuhneweg; Bernd;
(Duesseldorf, DE) ; Audenaert; Frans A.;
(Kaprijke, BE) ; Juergens; Michael; (Kastl,
DE) ; Schuell; Christoph T. R.; (Neuss, DE) ;
Habbe; Andrea; (Moers, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
3M INNOVATIVE PROPERTIES COMPANY |
St. Paul |
MN |
US |
|
|
Family ID: |
1000005324906 |
Appl. No.: |
17/045674 |
Filed: |
April 17, 2019 |
PCT Filed: |
April 17, 2019 |
PCT NO: |
PCT/IB2019/053201 |
371 Date: |
October 6, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B32B 2307/732 20130101;
B32B 2307/712 20130101; F05B 2280/6011 20130101; B32B 2307/54
20130101; F03D 1/0675 20130101; B32B 27/18 20130101; B32B 27/065
20130101; B64C 11/205 20130101; B32B 7/12 20130101; B64C 27/473
20130101; B32B 2305/022 20130101; B32B 27/283 20130101; B32B 27/40
20130101; B32B 2603/00 20130101; B32B 5/18 20130101; B32B 2375/00
20130101; B64C 2027/4736 20130101; F03D 80/40 20160501; B64D 15/00
20130101; B32B 27/08 20130101; B32B 2383/00 20130101; B32B 2266/14
20161101 |
International
Class: |
B32B 5/18 20060101
B32B005/18; B64C 11/20 20060101 B64C011/20; B64C 27/473 20060101
B64C027/473; B64D 15/00 20060101 B64D015/00; F03D 1/06 20060101
F03D001/06; F03D 80/40 20060101 F03D080/40; B32B 7/12 20060101
B32B007/12; B32B 27/06 20060101 B32B027/06; B32B 27/08 20060101
B32B027/08; B32B 27/40 20060101 B32B027/40; B32B 27/28 20060101
B32B027/28; B32B 27/18 20060101 B32B027/18 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 26, 2018 |
EP |
18169506.5 |
Claims
1. An aerodynamic surface comprising an edge portion and an
anti-icing stack disposed on the edge portion, wherein the
anti-icing stack comprises: a first layer being an erosion
protection layer having an elongation at break as determined
according to ASTM test standard D882-12 of greater than 100%; a
foam adhesive layer having a tensile modulus as determined
according to ASTM test standard D882-12 of less than 5 MPa, the
foam adhesive layer bonding the first layer to the edge portion of
the aerodynamic surface, the foam adhesive layer having a thickness
of at least 600 micrometers, wherein the thickness of the foam
adhesive layer is at least 50% of a total thickness of the
anti-icing stack, and a second layer disposed on the first layer
opposite the foam adhesive layer, the second layer being an
anti-icing layer.
2. The aerodynamic surface of claim 1, wherein the first layer is a
polyurethane-based elastomer, and the second layer comprises either
a polysiloxane acrylate copolymer or a polyurethane, an organic
thickener, and an ice-release additive.
3. An anti-icing stack comprising: an anti-icing layer; an
elastomeric erosion protection layer; and an additional layer,
wherein the additional layer is a foam layer; wherein the erosion
protection layer is disposed between the anti-icing layer and the
additional layer, wherein the additional layer has a thickness
greater than a thickness of the erosion protection layer and a
tensile modulus as determined according to ASTM test standard
D882-12 of no more than a tensile modulus as determined according
to ASTM test standard D882-12 of the erosion protection layer.
4. The anti-icing stack of claim 3, wherein the tensile modulus of
the additional layer is no more than 0.5 times the tensile modulus
of the erosion protection layer.
5. The anti-icing stack of claim 4, wherein the thickness of the
additional layer is greater than 2 times the thickness of the
erosion protection layer.
6. A method of reducing an ice adhesion of an erosion protection
layer for an aerodynamic surface, the method comprising: disposing
a first intermediate layer between the erosion protection layer and
the aerodynamic surface, the first intermediate layer comprises a
foam adhesive having a thickness greater than a thickness of the
erosion protection layer, and a tensile modulus as determined
according to ASTM test standard D882-12 of no more than a tensile
modulus as determined according to ASTM test standard D882-12 of
the erosion protection layer, and disposing an anti-icing layer on
the erosion protection layer opposite the first intermediate
layer.
7. The method of claim 6, wherein the step of disposing an
anti-icing layer on the erosion protection layer comprises coating
and then drying an anti-icing coating composition on the erosion
protection layer, the anti-icing coating composition comprising
either a polysiloxane acrylate copolymer or a polyurethane
dispersion, an organic thickener, a film-forming additive, and an
ice-release additive.
8. The method of claim 6, wherein the first intermediate layer has
a thickness greater than 2 times a thickness of the erosion
protection layer.
9. The method of claim 6, wherein disposing the first intermediate
layer between the erosion protection layer and the aerodynamic
surface comprises disposing the first intermediate layer on an edge
portion of the aerodynamic surface.
10. The method of claim 7, wherein the first intermediate layer has
a thickness greater than 2 times a thickness of the erosion
protection layer.
11. The method of claim 7, wherein disposing the first intermediate
layer between the erosion protection layer and the aerodynamic
surface comprises disposing the first intermediate layer on an edge
portion of the aerodynamic surface.
12. The method of claim 8, wherein disposing the first intermediate
layer between the erosion protection layer and the aerodynamic
surface comprises disposing the first intermediate layer on an edge
portion of the aerodynamic surface.
13. The method of claim 10, wherein disposing the first
intermediate layer between the erosion protection layer and the
aerodynamic surface comprises disposing the first intermediate
layer on an edge portion of the aerodynamic surface.
Description
BACKGROUND
[0001] The formation and accretion of ice on rotor blades, e. g.
rotor blades of wind turbines or helicopters, can hinder their
performance. Furthermore, rotor blades are subject to erosion
caused by the impact of airborne material, such as rain, sand, and
dust.
SUMMARY
[0002] In some aspects of the present description, an aerodynamic
surface including an edge portion and an anti-icing stack disposed
on the edge portion is provided. The anti-icing stack includes a
first layer and a foam adhesive layer bonding the first layer to
the edge portion of the aerodynamic surface. The first layer is at
least one of an erosion protection layer having an elongation at
break of greater than 100% or an anti-icing layer. The foam
adhesive layer has a tensile modulus of less than 5 MPa and a
thickness of at least 300 micrometers.
[0003] In some aspects of the present description, an anti-icing
stack including an anti-icing layer, an elastomeric erosion
protection layer, and an additional layer is provided. The erosion
protection layer is disposed between the anti-icing layer and the
additional layer. The additional layer has a thickness greater than
a thickness of the erosion protection layer and a tensile modulus
of no more than a tensile modulus the erosion protection layer.
[0004] In some aspects of the present description, a method of
reducing an ice adhesion of an erosion protection layer for an
aerodynamic surface is provided. The method includes disposing a
first intermediate layer between the erosion protection layer and
the aerodynamic surface, where the first intermediate layer has a
thickness greater than a thickness of the erosion protection layer
and a tensile modulus of no more than a tensile modulus of the
erosion protection layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1A is a schematic top view of a wind turbine blade;
[0006] FIG. 1B is a schematic cross-sectional view of the wind
turbine blade of FIG. 1A; and
[0007] FIGS. 2-4 are a schematic side views of anti-icing
stacks.
DETAILED DESCRIPTION
[0008] In the following description, reference is made to the
accompanying drawings that form a part hereof and in which various
embodiments are shown by way of illustration. The drawings are not
necessarily to scale. It is to be understood that other embodiments
are contemplated and may be made without departing from the scope
or spirit of the present description. The following detailed
description, therefore, is not to be taken in a limiting sense.
[0009] FIGS. 1A-1B are schematic top and cross-sectional views of a
wind turbine blade 110 having an aerodynamic surface 112 including
an edge portion 114. An anti-icing stack 100 is disposed on the
edge portion 114. The anti-icing stack 100 may be disposed on all
or only a portion of the length of the edge portion 114. The
cross-section of FIG. 1B is along a portion of the length of the
wind turbine blade where the anti-icing stack 100 is included. The
anti-icing stack 100 is preferably configured to protect the
aerodynamic surface 112 from ice buildup and may also protect the
aerodynamic surface 112 from erosion (e. g., caused by the impact
of rain). The anti-icing stack 100 includes at least two layers
(not shown in FIGS. 1A-1B) as described further elsewhere herein.
It has been found that using a sufficiently thick and sufficiently
soft layer between an erosion protection layer and an aerodynamic
surface reduces ice adhesion to the erosion protection layer.
Accordingly, an anti-icing stack which includes an erosion
protection layer and a soft layer adapted to be placed between the
erosion protection layer and the aerodynamic surface has an
anti-icing property even when the anti-icing stack does not include
a separate anti-icing layer according to some embodiments of the
present description. In some embodiments, an anti-icing stack
includes an anti-icing layer disposed on the erosion protection
layer to further improve the ice release properties of the
anti-icing stack. In other embodiments, a separate erosion
protection layer is omitted and an anti-icing layer is disposed on
the soft layer. In this case, the soft layer can improve the ice
release properties of the anti-icing layer compared to the
anti-icing layer without the soft layer.
[0010] In some embodiments, a method of reducing the ice adhesion
of an erosion protection layer (e. g., a thermoplastic
polyurethane) for an aerodynamic surface includes disposing a
sufficiently thick (e. g., thicker than the erosion protection
layer) and sufficiently soft (e. g., having a tensile modulus of no
more than a tensile modulus of the erosion protection layer)
intermediate layer between the erosion protection layer and the the
aerodynamic surface. In some embodiments, the intermediate layer
and the erosion protection layer are disposed on an edge portion of
the aerodynamic surface. In some embodiments, the intermediate
layer sufficiently reduces the ice adhesion to the erosion
protection layer that no additional anti-icing layer is needed. In
other embodiments, the method further includes disposing an
anti-icing layer on the erosion protection layer to further reduce
the ice adhesion.
[0011] In wind-turbine applications, it is typically preferred that
the anti-icing stacks be applied to the leading edge of the rotor
blade since this edge is prone to ice build-up and erosion.
However, the anti-icing stacks of the present description can also
be applied to other portions of the rotor blade, or to other types
of rotor blades, or to other aerodynamic surfaces, or to other
types of surfaces. In some embodiments, the anti-icing stacks are
applied to a rotor blade (e. g., a leading edge of the rotor blade
of a wind turbine) used in a helicopter, for example, or the
leading edge of an aircraft wing, for example. Other surfaces where
the anti-icing stacks can be applied include those in air
conditioners, antennas, high-voltage power lines, overhead
transmission lines, and satellite dishes.
[0012] FIG. 2 is a schematic side view of an anti-icing stack 200
which includes a first layer 220 and an additional layer 230. The
first layer 220 may be at least one of an erosion protection layer
having an elongation at break of greater than 100% (or greater than
200%, or greater than 300%, or greater than 500%, or greater than
600%, or in a range of 200% to 3000%) or an anti-icing layer (e.
g., the first layer 220 may be an erosion protection layer, or the
first layer 220 may be an anti-icing layer, or the first layer 220
may be both an erosion protection layer and an anti-icing layer).
The additional layer 230 is preferably soft (e. g., having a low
tensile modulus) and thick (e. g., thicker than the first layer
220). In some embodiments, the additional layer 230 has a tensile
modulus of no more than a tensile modulus of the first layer 220,
or no more than 0.8 times the tensile modulus of the first layer
220, or no more than 0.6 times the tensile modulus of the first
layer 220, or no more than 0.5 times the tensile modulus of the
first layer 220. In some embodiments, the additional layer 230 has
a tensile modulus of less than 5 MPa, or less than 3 MPa, or less
than 1 MPa. In some embodiments, the additional layer 230 has a
tensile modulus in a range of 100 kPa to 3 MPa, for example. In
some embodiments, first layer 220 is both an erosion protection
layer and an anti-icing layer. In some embodiments, first layer 220
is an anti-icing layer. In some embodiments, first layer 220 is an
erosion protection layer having an ice release property due, at
least in part, to properties of the additional layer 230 (e. g.,
tensile modulus and thickness). The first layer 220 has a thickness
of t1 and the additional layer 230 has a thickness of t2. In some
embodiments, t2 is greater than t1, or greater than 1.5 times t1,
or greater than 2 times t1, or greater than 3 times t1. or greater
than 4 times t1. In some embodiments, t2 is at least 50% of a total
thickness T of the anti-icing stack 200. In some embodiments, t2 is
at least 300 micrometers, or at least 500 micrometers, or at least
600 micrometers, or at least 800 micrometers, or at least 1000
micrometers, or at least 1100 micrometers. In some embodiments, t2
is in a range of 300 micrometers to 2 mm, for example.
[0013] The anti-icing stack 200 is preferably configured such that
when it is disposed on an aerodynamic surface (e. g., as
illustrated in FIGS. 1A-1B), the additional layer 230 faces the
aerodynamic surface and the first layer 220 faces away from the
aerodynamic surface. Since the additional layer 230 is disposed
between the first layer 220 and the aerodynamic surface, it may
also be referred to as an intermediate layer. In some embodiments,
the additional layer 230 is an adhesive layer which may be a foam
adhesive layer. Polymeric foam layers, for example, have been found
to provide the softness and thickness needed to improve the
anti-icing properties of the first layer 220. In some embodiments,
the additional layer 230 is a foam layer which is not an adhesive.
In this case, an adhesive layer (e. g., a pressure-sensitive
adhesive (PSA) layer) may be disposed between the additional layer
230 and the aerodynamic surface. In some embodiments, the
additional layer 230 is not a foam. For example, the additional
layer 230 may be a soft elastomer (e. g., having a tensile modulus
of less than 5 MPa or less than 3 MPa or less than 1 MPa).
[0014] Tensile modulus refers to Young's modulus unless indicated
differently. The tensile modulus and the elongation at break can be
determined as described in the ASTM test standard D882-12 "Standard
Test Method of Tensile Properties of Thin Plastic Sheeting". The
ASTM D882-12 standard utilizes an extensometer to grip a film
sample of the material to be tested at opposite ends of the sample,
apply a load to the sample, and determine the load verses extension
(distance between grips). The tensile modulus and elongation at
break are determined from the resulting load-extension curve. The
anti-icing stacks of the present description may also be
characterized in terms of a flexural modulus. The flexural modulus
may be determined as described in ASTM test standard D790-17
"Standard Test Methods for Flexural Properties of Unreinforced and
Reinforced Plastics and Electrical Insulating Materials". The ASTM
D790-17 standard utilizes a three-point loading system and
determines the applied load versus the deflection at a midway point
between supports. The flexural modulus is determined from the
resulting load-deflection curve.
[0015] In some embodiments, the anti-icing stack 200 includes a
second layer disposed on the first layer 220 opposite the
additional layer 230. In some embodiments, the first layer 220 is
an erosion protection layer and the second layer is an anti-icing
layer.
[0016] FIG. 3 is a schematic side view of an anti-icing stack 300
which includes an elastomeric erosion protection layer 320, an
anti-icing layer 325, and an additional layer 330. The erosion
protection layer 320 is disposed between the anti-icing layer 325
and the additional layer 330. The additional layer 330 is
preferably sufficiently soft and thick that it results in improved
anti-icing properties of the anti-icing stack 300. The additional
layer 330 may be as described for additional layer 230. For
example, the additional layer 330 may be a foam adhesive layer. The
erosion protection layer 320 may be as described for embodiments of
first layer 220 where there first layer 220 is an erosion
protection layer. For example, the erosion protection layer 320 may
have an elongation at break of greater than 100%. The thickness t1
of the erosion protection layer 320, the thickness t2 of the
additional layer 330 and the total thickness T of the anti-icing
stack 300 may be as described for the anti-icing stack 200. For
example, t2 may be greater than t1, or greater than 2 times t1, or
at least 300 micrometers, or at least 600 micrometers, or at least
50% of T.
[0017] FIG. 4 is a schematic side view of an anti-icing stack 400
which includes an elastomeric erosion protection layer 420, an
anti-icing layer 425, a first intermediate layer 430 and a second
intermediate layer 435. The erosion protection layer 420 is
disposed between the anti-icing layer 425 and the first
intermediate layer 430. The first intermediate layer 430, which is
preferably sufficiently soft and thick that it results in improved
anti-icing properties of the anti-icing stack 400, may be as
described for additional layer 230 or additional layer 330. The
anti-icing layer 425 may be as described for anti-icing layer 325
or as described for embodiments of first layer 220 where the first
layer 220 is an anti-icing layer. The erosion protection layer 420
may be as described for erosion protection layer 320 or as
described for embodiments of first layer 220 where the first layer
220 is an erosion protection layer. The second intermediate layer
435 may be an adhesive layer for attaching the anti-icing stack to
an aerodynamic surface. An additional adhesive layer (not
illustrated) may be disposed between the erosion protection layer
420 and the first intermediate layer 430. For example, a tape
including the erosion protection layer 420 and an adhesive layer
may be adhered to the first intermediate layer 430, which may be a
non-adhesive foam, for example. An additional adhesive layer may
similarly be included between first layer 220 and additional layer
230 or between elastomeric erosion protection layer 320 and
additional layer 330. In preferred embodiments, the first
intermediate layer 430 is a foam layer and the second intermediate
layer 435 is an adhesive layer. The thickness t1 of the erosion
protection layer 420, the thickness t2 of the first intermediate
layer 430 and the total thickness T of the anti-icing stack 400 may
be as described for the anti-icing stack 200 or for anti-icing
stack 400.
[0018] In some embodiments, additional layer(s) not shown in FIGS.
2-4 are included. For example, additional adhesive layers can be
included as described above. In some embodiments, additional
non-adhesive layer(s) are included. For example, is some
embodiments, the first layer 220, the elastomeric erosion
protection layer 320, or the elastomeric erosion protection layer
420 is applied to a substrate (e. g., coated onto the substrate)
which is then adhered to the additional layer 230, the additional
layer 330, or the first intermediate layer 430, respectively. If
such a substrate is included, it is preferred that the substrate be
sufficiently thin and flexible (e. g., a polymeric substrate having
a thickness of no more than about 125 micrometers) that the
protective or anti-icing stack remains flexible so that the
additional layer 230, the additional layer 330, or the first
intermediate layer 430 is effective in improving the ice release
properties of the respective anti-icing stack. In some embodiments,
the anti-icing stack 200, or the anti-icing stack 300, or the
anti-icing stack 400 has a flexural modulus of less than 10 MPa. In
some embodiments, the flexural modulus is less than 5 MPa, or less
than 3 MPA, or less than 1 MPa. In some embodiments, the flexural
modulus is in a range of 100 kPa to 3 MPA.
[0019] Suitable adhesives (e. g., foam adhesives) that can be used
as additional layer 230 or additional layer 330, for example,
include pressure-sensitive adhesives (e. g. acrylic, rubber (e. g.,
isoprene based rubbers or styrene-butadiene based rubbers), and
silicone based adhesives) and structural adhesives (e. g. epoxy,
urethane, and acrylic based adhesives). The adhesive can be
provided in a tape. Suitable foam tapes include 3M VHB 4433, 3M VHB
4611, 3M VHB 5952, 3M VHB GPH-060GF, 3M VHB GPH-110GF, and 3M VHB
GPH-160GF acrylic foam tapes available from 3M Company (St. Paul,
Minn., USA). These types of adhesives can also be used for first
intermediate layer 430 and/or second intermediate layer 435. In
some embodiments, first intermediate layer 430 is not an adhesive.
For example, non-adhesive foams may be used for first intermediate
layer 430 when the second intermediate layer 435 is an adhesive
layer.
[0020] It is preferred that the foam layer, or other type of
additional or intermediate layer, have a thickness greater than a
thickness of the erosion protection layer. In some embodiments, a
foam adhesive layer, or other type of additional or intermediate
layer, has a thickness of at least 300 micrometers, or of at least
500 micrometers, or at least 600 micrometers, or of at least 800
micrometers, or of at least 1000 micrometers, or at least 1100
micrometers. In some embodiments, a foam adhesive layer, or other
type of additional or intermediate layer, has a thickness of at
least 300 micrometers, or of at least 500 micrometers, or at least
600 micrometers, or of at least 800 micrometers, or of at least
1000 micrometers, or at least 1100 micrometers and no more than 3
mm, or no more than 2 mm, or no more than 1.8 mm. In some
embodiments, a foam adhesive layer, or other type of additional or
intermediate layer, has a thickness greater than a thickness of the
erosion protection layer, or greater than 1.5 times a thickness of
the erosion protection layer, or greater than twice a thickness of
the erosion protection layer, or greater than 3 times a thickness
of the erosion protection layer, or greater than 4 times a
thickness of the erosion protection layer. It is preferred that the
foam layer, or other type of additional or intermediate layer, have
a tensile modulus less than 5 MPa, or less than 3 MPa, or less than
1 MPa. It is preferred that the foam layer, or other type of
additional or intermediate layer, have a tensile modulus of no more
than the tensile modulus of the erosion protection layer, or no
more than 0.8 times the tensile modulus of the erosion protection
layer, or no more than 0.6 times the tensile modulus of the erosion
protection layer, or no more than 0.5 times the tensile modulus of
the erosion protection layer.
[0021] The additional layer 230 or additional layer 330 or first
intermediate layer 430 may or may not be uniform layers having no
distinct sublayers. In some embodiments, the additional layer 230
or additional layer 330 or first intermediate layer 430 includes
sublayers. For example, a tape including adhesive foams on opposing
sides of a carrier substrate may be used for any of these layers.
In this case, the tape may be considered to be a layer having three
sublayers--the carrier substrate and the two opposing adhesive foam
layers.
[0022] Suitable materials for the erosion protection layer (e. g.,
first layer 220 in embodiments where this layer is an erosion
protection layer, erosion protection layer 320, or erosion
protection layer 420) include elastomers such as polyurethane-based
elastomers and silicone-based elastomers. Example materials include
3M Wind Blade Protection Coating W4600 available from 3M Company,
St. Paul, Minn., USA. It is preferred that the erosion protection
layer be an elastomer having a large elongation at break. In some
embodiments, the erosion protection layer has an elongation at
break of greater than 100%, or greater than 200%, or greater than
300%, or greater than 500%, or greater than 600%. In some
embodiments, the erosion protection layer, has an elongation at
break in a range of 200% to 3000%. In some embodiments, the foam
layer, or other type of additional or intermediate layer, also has
an elongation at break in any of these ranges (e. g., greater than
100% or in a range of 200% to 3000%). 3M Wind Blade Protection
Coating W4600 has an elongation at break above 600%. Other useful
erosion protection materials include 3M Wind Blade Protection
Coating W4601, 3M Wind Blade Protection Tape W8607, and 3M Wind
Blade Protection Tape W8750 all available from 3M Company, St.
Paul, Minn., USA, and all having an elongation at break above 600%.
In embodiments where a tape is used, the adhesive layer of the tape
is preferably disposed between the erosion protection layer and the
foam layer, or other type of additional or intermediate layer.
[0023] Suitable materials for the anti-icing layer (e. g., first
layer 220 in embodiments where this layer is an anti-icing layer,
anti-icing layer 325, or anti-icing layer 425) includes polymers
comprising polydimethyl siloxane segments. Suitable anti-icing
layers including siloxane materials are described, for example, in
PCT Publ. No. WO 2017/189475 (Meuler et al.). In some embodiments,
an anti-icing layer includes fluorochemical materials. Suitable
anti-icing layers including fluorochemical materials are described,
for example, in PCT Publ. No. WO 2017/189215 (Elsbernd et al.).
[0024] In some embodiments, an anti-icing layer is formed from a
polysiloxane acrylate copolymer. Suitable polysiloxane acrylate
copolymers can be obtained as a reaction product (free radical
polymerization) of a polysiloxane macromonomer and an acrylate
comonomer in an organic solvent with an initiator. Suitable
polysiloxane macromonomers include those available from Shin-Etsu
Chemical Co., Ltd. (Tokyo, Japan) such as X-22-2426 and KF-2012.
Polysiloxane macromonomers having a molecular weight of at least
4000 g/mole are preferred as such macromonomers have been found to
result in improved anti-icing properties compared to using lower
molecular weight macromonomers. Suitable acrylate comonomers
include lauryl methacrylate (LMA), butyl acrylate (BA), 2 ethyl
hexyl methacrylate (2-EHMA), butyl methacrylate (BMA), isobutyl
methacrylate (iBMA), and methyl methacrylate (MMA). BMA is
preferred as this has been found to result in improved anti-icing
properties compared to using other acrylate comonomers. Suitable
organic solvents include tert-butanol (t-BuOH). Suitable initiators
include 2,2'-azobis(2-methylbutyronitrile) initiator which is
available from Wako Pure Chemical Industries, Ltd. (Japan) under
the tradename V-59. The polymerization results in a polysiloxane
acrylate copolymer having an acrylate copolymer backbone with
polysiloxane side chains. The solution containing the polysiloxane
acrylate copolymer, which may be referred to as an anti-icing
coating composition, can be coated and then dried to remove the
organic solvent resulting in an anti-icing layer formed from the
polysiloxane acrylate copolymer.
[0025] In some embodiments, an anti-icing layer is formed by
coating and drying a coating composition. In some embodiments, the
coating composition includes a polyurethane dispersion, an organic
thickener, a film-forming additive, and an ice-release additive
which is an additive for improving the ice-release properties of
the resulting anti-icing layer. Suitable polyurethane dispersions
include aliphatic polyurethane dispersions such as NEOREZ R-2005
available from DSM Resins, Inc. (Augusta, Ga., USA). Suitable
organic thickeners include Xanthan and nonionic urethane rheology
modifiers such as ACRYSOL RM-8W available from Dow Chemical Company
(Midland, Mich., USA). Suitable film-forming additives include
coalescing solvents such as ether-alcohols. Useful ether alcohols
include propylene glycol n-butyl ether (e. g., PnB available from
Dow Chemical Company), dipropylene glycol monomethyl ether (e. g.,
DPM available from Dow Chemical Company), dipropylene glycol
n-butyl ether (e. g., DPnB available from Dow Chemical Company),
tripropylene glycol monomethyl ether (e. g., TMP from Lyondell
Basell Industries, Houston, Tex., USA). Suitable ice-release
additives include additives comprising at least one of a silicon
containing additive or a fluorine containing additive. Suitable
silicon containing additives include additives comprising a
polydimethyl siloxane moiety. Suitable fluorine containing
additives include additives comprising at least one of a
fluorinated alkyl moiety or a perfluoroether moiety. The
ice-release additive may be a surfactant and/or may be an
amphiphilic additive. An amphiphilic additive includes low surface
energy segments (e. g., a polydimethyl siloxane moiety or a
fluorinated alkyl moiety or a perfluoroether moiety) and high
surface energy segments (e. g., a polyoxyethylene moiety, or an
acid or acid-salt moiety). Amphiphilic additives are preferred so
that the additive dissolves or disperses in the aqueous
polyurethane dispersion and provides a low surface energy to
improve the ice release of the resulting anti-icing layer. Suitable
amphiphilic additives include polyether-modified
polydimethylsiloxane (e. g., BYK-333 available from BYK-Chemie
GmbH, Germany) and polyether-modified fluorinated acrylate polymers
(e. g., FC-4430 and FC-4432 available from 3M Company, St. Paul,
Minn., USA).
[0026] The following is a list of illustrative embodiments of the
present description.
[0027] Embodiment 1 is an aerodynamic surface comprising an edge
portion and an anti-icing stack disposed on the edge portion,
wherein the anti-icing stack comprises:
a first layer being at least one of an erosion protection layer
having an elongation at break of greater than 100% or an anti-icing
layer; and a foam adhesive layer having a tensile modulus of less
than 5 MPa, the foam adhesive layer bonding the first layer to the
edge portion of the aerodynamic surface, the foam adhesive layer
having a thickness of at least 300 micrometers.
[0028] Embodiment 2 is the aerodynamic surface of Embodiment 1,
wherein the elongation at break and the tensile modulus are as
determined according to ASTM test standard D882-12.
[0029] Embodiment 3 is the aerodynamic surface of Embodiment 1 or
2, wherein the elongation at break of the erosion protection layer
is greater than 200%.
[0030] Embodiment 4 is the aerodynamic surface of any one of
Embodiments 1 to 3, wherein the elongation at break of the erosion
protection layer is greater than 300%.
[0031] Embodiment 5 is the aerodynamic surface any one of
Embodiments 1 to 4, wherein the elongation at break of the erosion
protection layer is greater than 500%.
[0032] Embodiment 6 is the aerodynamic surface of any one of
Embodiments 1 to 5, wherein the elongation at break of the erosion
protection layer is in a range from 200% to 3000%.
[0033] Embodiment 7 is the aerodynamic surface of any one of
Embodiments 1 to 6, wherein the thickness of the foam adhesive
layer is at least 50% of a total thickness of the anti-icing
stack.
[0034] Embodiment 8 is the aerodynamic surface of any one of
Embodiments 1 to 7, wherein the first layer is the erosion
protection layer.
[0035] Embodiment 9 is the aerodynamic surface of Embodiment 8,
wherein the anti-icing stack further comprises a second layer
disposed on the first layer opposite the foam adhesive layer, the
second layer being an anti-icing layer.
[0036] Embodiment 10 is the aerodynamic surface of Embodiment 9,
wherein the first layer is a polyurethane-based elastomer, and the
second layer comprises: polyurethane, an organic thickener, and an
ice-release additive.
[0037] Embodiment 11 is the aerodynamic surface of Embodiment 10,
wherein the ice-release additive comprises at least one of a
silicon containing additive or a fluorine containing additive.
[0038] Embodiment 12 is the aerodynamic surface of Embodiment 11,
wherein the ice-release additive comprises the silicon containing
additive, the silicon containing additive comprising a polydimethyl
siloxane moiety.
[0039] Embodiment 13 is the aerodynamic surface of Embodiment 11,
wherein the ice-release additive comprises the fluorine containing
additive, the fluorine containing additive comprising at least one
of a fluorinated alkyl moiety or a perfluoroether moiety.
[0040] Embodiment 14 is the aerodynamic surface of any one of
Embodiments 10 to 13, wherein the ice-release additive comprises a
surfactant.
[0041] Embodiment 15 is the aerodynamic surface of any one of
Embodiments 10 to 14, wherein the ice-release additive comprises an
amphiphilic additive.
[0042] Embodiment 16 is the aerodynamic surface of Embodiment 9,
wherein the anti-icing layer comprises a polysiloxane acrylate
copolymer.
[0043] Embodiment 17 is the aerodynamic surface of Embodiment 9,
wherein the first layer is a polyurethane-based elastomer, and the
second layer comprises either a polysiloxane acrylate copolymer or
a polyurethane, an organic thickener, and an ice-release
additive.
[0044] Embodiment 18 is the aerodynamic surface of Embodiment 9,
wherein the first layer is a polyurethane-based elastomer, and the
second layer comprises a polymer comprising polydimethyl siloxane
segments.
[0045] Embodiment 19 is the aerodynamic surface of any one of
Embodiments 9 to 18, wherein the anti-icing stack has a flexural
modulus of less than 10 MPa.
[0046] Embodiment 20 is the aerodynamic surface of Embodiment 19,
wherein the flexural modulus is as determined according to ASTM
test standard D790-17.
[0047] Embodiment 21 is the aerodynamic surface of any one of
Embodiments 1 to 20, wherein the thickness of the foam adhesive
layer is at least 600 micrometers.
[0048] Embodiment 22 is an anti-icing stack comprising:
an anti-icing layer; an elastomeric erosion protection layer; and
an additional layer, wherein the erosion protection layer is
disposed between the anti-icing layer and the additional layer,
wherein the additional layer has a thickness greater than a
thickness of the erosion protection layer and a tensile modulus of
no more than a tensile modulus of the erosion protection layer.
[0049] Embodiment 23 is the aerodynamic surface of Embodiment 22,
wherein the tensile modulus of the erosion protection layer and the
tensile modulus of the additional layer are as determined according
to ASTM test standard D882-12.
[0050] Embodiment 24 is the anti-icing stack of Embodiment 22 or
23, wherein the additional layer is an adhesive layer.
[0051] Embodiment 25 is the anti-icing stack of any one of
Embodiments 22 to 24, wherein the additional layer is a foam
adhesive layer.
[0052] Embodiment 26 is the anti-icing stack of any one of
Embodiments 22 to 23, wherein the additional layer is a foam
layer.
[0053] Embodiment 27 is the anti-icing stack of Embodiment 26,
further comprising an adhesive layer, the foam layer disposed
between the adhesive layer and the elastomeric erosion protection
layer.
[0054] Embodiment 28 is the anti-icing stack of any one of
Embodiments 22 to 27, wherein the tensile modulus of the additional
layer is no more than 0.5 times the tensile modulus of the erosion
protection layer.
[0055] Embodiment 29 is the anti-icing stack of any one of
Embodiments 22 to 28, wherein the thickness of the additional layer
is greater than 2 times the thickness of the erosion protection
layer.
[0056] Embodiment 30 is the anti-icing stack of any one of
Embodiments 22 to 29 having a flexural modulus of less than 10
MPa.
[0057] Embodiment 31 is the anti-icing stack of Embodiment 30,
wherein the flexural modulus is as determined according to ASTM
test standard D790-17.
[0058] Embodiment 32 is the aerodynamic surface of any one of
Embodiments 22 to 31, wherein the thickness of the additional layer
is at least 600 micrometers.
[0059] Embodiment 33 is a method of reducing an ice adhesion of an
erosion protection layer for an aerodynamic surface, the method
comprising:
disposing a first intermediate layer between the erosion protection
layer and the aerodynamic surface, the first intermediate layer
having a thickness greater than a thickness of the erosion
protection layer, and a tensile modulus of no more than a tensile
modulus of the erosion protection layer.
[0060] Embodiment 34 is the aerodynamic surface of Embodiment 33,
wherein the tensile modulus of the erosion protection layer and the
tensile modulus of the first intermediate layer are as determined
according to ASTM test standard D882-12.
[0061] Embodiment 35 is the method of Embodiment 33 or 34, wherein
the first intermediate layer has an elongation at break of greater
than 100%.
[0062] Embodiment 36 is the method of any one of Embodiments 33 to
35, wherein the first intermediate layer comprises a foam
adhesive.
[0063] Embodiment 37 is the method of any one of Embodiments 33 to
36, further comprising disposing a second intermediate layer
between the first intermediate layer and the aerodynamic
surface.
[0064] Embodiment 38 is the method of Embodiment 37, wherein the
first intermediate layer comprises a foam and the second
intermediate layer comprises an adhesive.
[0065] Embodiment 39 is the method of any one of Embodiments 33 to
38, further comprising disposing an anti-icing layer on the erosion
protection layer opposite the first intermediate layer.
[0066] Embodiment 40 is the method of Embodiment 39, wherein the
step of disposing an anti-icing layer on the erosion protection
layer comprises coating and then drying an anti-icing coating
composition on the erosion protection layer.
[0067] Embodiment 41 is the method of Embodiment 39 wherein the
step of disposing an anti-icing layer on the erosion protection
layer comprises coating and then drying an anti-icing coating
composition on the erosion protection layer, the anti-icing coating
composition comprising either a polysiloxane acrylate copolymer or
a polyurethane dispersion, an organic thickener, a film-forming
additive, and an ice-release additive.
[0068] Embodiment 42 is the method of Embodiment 40 or 41, wherein
the anti-icing coating composition comprises a polyurethane
dispersion, an organic thickener, a film-forming additive, and an
ice-release additive.
[0069] Embodiment 43 is the method of Embodiment 41 or 42, wherein
the ice-release additive comprises a polydimethyl siloxane
moiety.
[0070] Embodiment 44 is the method of Embodiment 41 or 42, wherein
the ice-release additive comprises at least one of a fluorinated
alkyl moiety or a perfluoroether moiety.
[0071] Embodiment 45 is the method of Embodiment 41 or 42, wherein
the ice-release additive comprises an amphiphilic additive.
[0072] Embodiment 46 is the method of Embodiment 40 or 41, wherein
the anti-icing coating composition comprises a polysiloxane
acrylate copolymer.
[0073] Embodiment 47 is the method of any one of Embodiments 33 to
46, wherein the tensile modulus of the first intermediate layer is
less than 5 MPa.
[0074] Embodiment 48 is the method of any one of Embodiments 33 to
47, wherein the tensile modulus of the first intermediate layer is
less than 3 MPa.
[0075] Embodiment 49 is the method of any one of Embodiments 33 to
48, wherein the first intermediate layer has a thickness of at
least 600 micrometers.
[0076] Embodiment 50 is the method of any one of Embodiments 33 to
49, wherein the first intermediate layer has a thickness greater
than 2 times a thickness of the erosion protection layer.
[0077] Embodiment 51 is the method of any one of Embodiments 33 to
50 being a method for reducing an ice adhesion of an erosion
protection layer disposed on an edge portion of the aerodynamic
surface.
[0078] Embodiment 52 is the method of any one of Embodiments 33 to
51, wherein disposing the first intermediate layer between the
erosion protection layer and the aerodynamic surface comprises
disposing the first intermediate layer on an edge portion of the
aerodynamic surface.
[0079] Embodiment 53 is the method of any one of Embodiments 33 to
52, wherein the aerodynamic surface is a rotor blade surface.
EXAMPLES
Materials
[0080] 3M 9415 is a repositionable tape having a 50 .mu.m PET
carrier and available from 3M Company (St. Paul, Minn., USA). 3M PU
8591 is a polyurthane protective film available from 3M Company
(St. Paul, Minn., USA) and having a thickness of about 300 .mu.m.
3M PU 8592 is a polyurthane protective film available from 3M
Company (St. Paul, Minn., USA) and having a thickness of about 150
.mu.m. 3M Wind Blade Protection Tape W8607 is available from 3M
Company (St. Paul, Minn., USA). 3M Wind Blade Protection Coating
W4600 is available from 3M Company (St. Paul, Minn., USA). BYK-333
and BYK-378 are additives available from BYK/Altana (Germany). DPM
(dipropylene glycol monomethyl ether) is available from
Sigma-Aldrich (St. Louis, Mo., USA). FC-4430 and FC-4432 are
fluorosurfactants available from 3M Company (St. Paul, Minn., USA).
MIRAPOL Surf-S 210 is a polymer additive available from Solvay S.A.
(Belgium). Neorez R-2005 is an aqueous polyurethane dispersion (35
wt % solids) available from DSM Resins, Inc. (Augusta, Ga., USA).
TEGO Phobe and TEGO Glide additives are available from Evonik
Industries (Germany). VHB GPH-060GF is an acrylic foam tape
available from 3M Company (St. Paul, Minn., USA) and having a
thickness of about 600 .mu.m. VHB GPH-110GF is an acrylic foam tape
available from 3M Company (St. Paul, Minn., USA) and having a
thickness of about 1100 .mu.m. VHB GPH-160GF is an acrylic foam
tape available from 3M Company (St. Paul, Minn., USA) and having a
thickness of about 1600 .mu.m. Xanthan is available from
Sigma-Aldrich (St. Louis, Mo., USA). Ice Release Coating IRC1 is a
polysiloxane acrylate copolymer ice release coating solution
prepared as follows: A 250 ml reaction bottle was charged
respectively with 5.25 g (35 w %) X-22-2426 (silicone methacrylate
macromonomer available from Shin-Etsu), 9.75 g (65 w %) BMA (butyl
methacrylate available from Sigma-Aldrich), 45.0 g t.BuOH
(t.butanol available from Sigma-Aldrich) and 0.045 g V-59
(2,2'-azobis(2-methylbutyronitrile) initiator available from Wako).
The bottle was degassed with waterjet vacuum, followed by breaking
the vacuum with nitrogen atmosphere. This procedure was repeated 3
times. The reaction bottle was sealed and run for 4 hours in a
preheated Launder-O-meter at 70.degree. C. After cooling 0.045 g
V-59 was added, the bottle was again degassed and covered with
nitrogen atmosphere. The reaction bottle was then run for another
16 hours at 70.degree. C., yielding a clear, colorless semi-viscous
solution containing 25% polymer solids.
Examples 1-9
[0081] Coating compositions were prepared as indicated in Table 1
in a solvent of deionized water (DIW) and DPM in an 85:15 ratio by
weight. The coating compositions were prepared on a 50 g scale. The
corresponding amounts of materials were mixed in a glass jar,
equipped with a magnetic stirrer in the following order: 1.
DIW/DPM, 2. Neorez R-2005, 3. Xanthan, 4. Amphiphilic additive.
After addition of Xanthan, the mixture was allowed to stir for
about 1 hour to ensure a homogeneous mixture. An W8607 tape was
laminated onto a glass test plate (5.times.15 cm, obtained from
Rocholl GmbH, Germany) and coated with a #10 Meyer Bar (wet coating
thickness: 23 .mu.m) and allowed to dry for 48 hours at room
temperature before testing. The coatings were evaluated for wetting
and coating appearance.
TABLE-US-00001 TABLE 1 Coat. Total R-2005 Xanthan Additive Coating
No. wt % (wt %) (wt %) (Type, wt %) Wetting Appearance 1 10 10 --
-- Poor Poor 2 10 9.42 0.08 -- Medium Good 3 10 9.42 0.08 TEGO
Glide Good Slight 482, 0.5 defects 4 10 9.42 0.08 TEGO Glide Good
Good 100, 0.5 5 10 9.42 0.08 TEGO Glide Good Good 410, 0.5 6 10
9.42 0.08 TEGO Glide Good Slight 440, 0.5 defects 7 10 9.42 0.08 3M
FC-4430, Good Good 0.5 8 10 9.42 0.08 3M FC-4432, Good Good 0.5 9
10 9.42 0.08 BYK-333, 0.5 Good Good 10 10 9.42 0.08 BYK-378, 0.5
Good Defects 11 10 9.42 0.08 MIRAPOL Good Slight Surf-S defects
210, 0.5
[0082] For selected formulations, which showed good wetting and
coating appearance after coating on W8607, additional tests were
performed. The results of theses tests are provided in Table 2.
[0083] The coatings were visually inspected for coating homogeneity
using the following scale: 5: homogeneous, 4: few local defects, 3:
even distribution of slight defects, 2: even distribution of high
number of defects, 1: even distribution of significant number of
defects.
[0084] The coatings were visually inspected for transparency using
the following scale: good (fully transparent, no change in
transparency compared to untreated film), medium (slightly hazy),
poor (strongly hazy, significant change in transparency compared to
untreated film).
[0085] A droplet test was carried out by placing an 0.5 mL droplet
of water on the coated surface. The droplet was covered with a cup
to avoid evaporation and stored at room temperature. After 2 hours,
the cup was removed and the drop was removed by soaking with a
tissue. The surface was then visually inspected and rated from 5
(no change in coating appearance, such as swelling, appearance,
mechanics) to 1 (significant changes).
[0086] Ice-column tests were carried out as follows. A plastic
cuvette was modified by drilling a hole of about 4 mm square close
to the bottom. The modified cuvette was placed upside down on a
coated test plate and fixed with two rubber rings. After that, the
construction was cooled to -40.degree. C. for 30 min in a freezer.
The cuvette was then filled with a suitable amount of cold (about
8.degree. C.) deionized water, followed by cooling the construction
overnight in a freezer (-40.degree. C.). On the next day, the
rubber rings were removed and the test specimen was placed in a
Zwick tensile tester with a cooling chamber (-10.degree. C.) and
the force to remove the ice column was measured. An average of 5
independent measurements are reported in Table 2.
TABLE-US-00002 TABLE 2 Coat. No. Additive Transparency Homogeneity
Droplet Test ICT (kPa) 2 none good 4 -- 342 .+-. 32 7 FC-4430 good
5 5 211 .+-. 23 8 FC-4432 good 4 5 179 .+-. 31 9 BYK-333 good 4 3
269 .+-. 33 Uncoated -- -- -- -- 684 .+-. 119 W8607
[0087] Anti-icing stacks can be made by applying coatings 3-11 onto
an erosion protection layer disposed on a foam layer, for example.
Examples 1-9 are anti-icing stacks prepared by coating W8607 tapes
with coating numbers 3-11, respectively, and laminating each of the
coated tapes to a foam layer such as a foam adhesive layer.
Suitable foam adhesive layers are provided, for example, by 3M VHB
4433, 3M VHB 4611, 3M VHB 5952, 3M VHB GPH-060GF, 3M VHB GPH-110GF,
and 3M VHB GPH-160GF acrylic foam tapes available from 3M Company
(St. Paul, Minn., USA).
Example 10
[0088] An erosion protection coating (3M Wind Blade Protection
Coating W4600) was applied to a substrate which was then adhered to
a leading edge of an aerodynamic surface using a foam adhesive. The
substrate was included for ease of coating. To illustrate the
improvement that can be achieved from using a soft layer between
the erosion protection layer and the aerodynamic surface, the
substrate was selected to be either a rigid (0.5 mm thick) aluminum
substrate (Test Specimen 1) or a flexible (0.03 mm thick) aluminum
substrate (Test Specimen 2).
[0089] A 300 .mu.m W4600 layer was applied by knife coating on each
aluminum substrate at 23.degree. C. and 50% relative humidity
(r.h.). After an 8 h curing interval at 23.degree. C. and 50% r.h.
the sheets were further applied to an approximately 1 mm
double-sided acrylic foam tape and allowed to fully cure for
another 3 days.
[0090] The ice-release properties of the multilayer constructions
were tested using an Adverse Environment Rotor Test Stand (AERTS)
which included two rotor blades attached to a motor in a test
chamber. Test specimens were applied to an aerodynamic profile
located at the rotor blade tip and the environment was conditioned
to a specified temperature (-8.degree. C. or -12.degree. C.). At a
tip speed of 70 m/s, water droplets with an MVD (median droplet
diameter) of 20 .mu.m were sprayed into the test chamber forcing
ice build-up on the test profile leading edge. When the centrifugal
force of the ice build-up exceeds the ice-release force an
anti-icing event occurs. This allowed an ice adhesion strength to
be determined. Three measurements were taken for each of the two
rotor blade arms and an average and standard deviation of the ice
adhesion strength were determined.
[0091] For Test Specimen 1, the release forces at -12.degree. C.
were too high to measure. At -8.degree. C., the average ice
adhesion strength for Test Specimen 1 was 18.3 psi and the standard
deviation was 3.7 psi.
[0092] At -12.degree. C. the average ice adhesion strength for Test
Specimen 2 was 12.9 psi and the standard deviation was 3.7 psi. At
-8.degree. C., the average ice adhesion strength for Test Specimen
2 was 3.8 psi and the standard deviation was 1.9 psi.
Examples 11-21 and Comparative Examples C1-C2
[0093] An erosion protection layer was applied to a substrate, as
indicated in Table 3. In some cases (as indicated Table 3), the
IRC1 ice release coating was applied to the erosion protection
layer using a #10 Meyer Bar (wet coating thickness: 23 .mu.m) and
allowed to dry at room temperature for 48 hours. The 3M PU 8591
layers were applied without including a PSA layer and the W4600
coating was applied at a 300 .mu.m thickness. Coatings were allowed
to fully cure before further testing.
[0094] Ice-column tests were carried out as described for Examples
1-9. Four measurements were taken for each sample and an average of
the ice release force was determined and is reported in Table
3.
TABLE-US-00003 TABLE 3 Ice Release Erosion Protection Ice Release
Force Example Substrate Layer Coating (N/cm.sup.2) 11 VHB GPH-060GF
(600 .mu.m) 3M PU 8591 (300 .mu.m) -- 40 12 VHB GPH-110GF (1100
.mu.m) 3M PU 8591 (300 .mu.m) -- 28 13 VHB GPH-160GF (1600 .mu.m)
3M PU 8591 (300 .mu.m) -- 28 14 VHB GPH-060GF (600 .mu.m) 3M PU
8592 (150 .mu.m) -- 41 15 VHB GPH-110GF (1100 .mu.m) 3M PU 8592
(150 .mu.m) -- 18 16 VHB GPH-160GF (1600 .mu.m) 3M PU 8592 (150
.mu.m) -- 22 17 VHB GPH-060GF (600 .mu.m) 3M PU 8591 (300 .mu.m)
IRC1 12 18 VHB GPH-110GF (1100 .mu.m) 3M PU 8591 (300 .mu.m) IRC1
11 19 VHB GPH-160GF (1600 .mu.m) 3M PU 8591 (300 .mu.m) IRC1 9 20
VHB GPH-110GF (1100 .mu.m) W4600 (300 .mu.m) -- 31 C1 3M 9415 (50
.mu.m) W4600 (300 .mu.m) -- 78 21 VHB GPH-110GF (1100 .mu.m) W4600
(300 .mu.m) IRC1 8 C2 3M 9415 (50 .mu.m) W4600 (300 .mu.m) IRC1
11
[0095] All references, patents, and patent applications referenced
in the foregoing are hereby incorporated herein by reference in
their entirety in a consistent manner. In the event of
inconsistencies or contradictions between portions of the
incorporated references and this application, the information in
the preceding description shall control.
[0096] Descriptions for elements in figures should be understood to
apply equally to corresponding elements in other figures, unless
indicated otherwise. Although specific embodiments have been
illustrated and described herein, it will be appreciated by those
of ordinary skill in the art that a variety of alternate and/or
equivalent implementations can be substituted for the specific
embodiments shown and described without departing from the scope of
the present disclosure. This application is intended to cover any
adaptations or variations of the specific embodiments discussed
herein. Therefore, it is intended that this disclosure be limited
only by the claims and the equivalents thereof.
* * * * *