U.S. patent application number 16/520381 was filed with the patent office on 2020-02-27 for thermally-conductive material with good sound absorption properties.
The applicant listed for this patent is Carl Freudenberg KG. Invention is credited to Jochen Bechtum, Guenter Frey, Matthias Herzog, Sarah Illing, Werner Kattge, Dominic Kramer, Maria Teresa Rodriguez Charles, Hartwig von der Muehlen, Rudolf Wagner.
Application Number | 20200063335 16/520381 |
Document ID | / |
Family ID | 66998134 |
Filed Date | 2020-02-27 |
United States Patent
Application |
20200063335 |
Kind Code |
A1 |
Kramer; Dominic ; et
al. |
February 27, 2020 |
THERMALLY-CONDUCTIVE MATERIAL WITH GOOD SOUND ABSORPTION
PROPERTIES
Abstract
A thermally-conductive material includes: a textile fabric; and
a graphite-containing, thermally-conductive coating, in which
graphite is present in a proportion of 5 wt % to 50 wt % relative
to a total weight of the thermally-conductive material. The
thermally-conductive material has a flow resistance of 60 Pa*s/m to
400 Pa*s/m. In an embodiment, a proportion of graphite in relation
to the thermally-conductive coating is more than 50 wt %.
Inventors: |
Kramer; Dominic; (Frankfurt
am Main, DE) ; Bechtum; Jochen; (Weinheim, DE)
; Wagner; Rudolf; (Muellheim, DE) ; Illing;
Sarah; (Birkenau, DE) ; Frey; Guenter;
(Schliengen, DE) ; Kattge; Werner; (Rimbach,
DE) ; von der Muehlen; Hartwig; (Heidelberg, DE)
; Herzog; Matthias; (Ballrechten-Dottingen, DE) ;
Rodriguez Charles; Maria Teresa; (Terrassa, ES) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Carl Freudenberg KG |
Weinheim |
|
DE |
|
|
Family ID: |
66998134 |
Appl. No.: |
16/520381 |
Filed: |
July 24, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F24D 3/165 20130101;
E04B 1/8409 20130101; D04H 1/4218 20130101; D04H 1/58 20130101;
D06M 11/74 20130101; D04H 1/425 20130101 |
International
Class: |
D06M 11/74 20060101
D06M011/74; D04H 1/425 20060101 D04H001/425; D04H 1/4218 20060101
D04H001/4218; D04H 1/58 20060101 D04H001/58 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 24, 2018 |
DE |
102018120713.1 |
Claims
1. A thermally-conductive material, comprising: a textile fabric;
and a graphite-containing, thermally-conductive coating, in which
graphite is present in a proportion of 5 wt % to 50 wt % relative
to a total weight of the thermally-conductive material, wherein the
thermally-conductive material has a flow resistance of 60 Pa*s/m to
400 Pa*s/m.
2. The thermally-conductive material according to claim 1, wherein
a proportion of graphite in relation to the thermally-conductive
coating is more than 50 wt %.
3. The thermally-conductive material according to claim 1, wherein
a proportion of polymer binder in the thermally-conductive coating
and/or between the thermally-conductive coating and the textile
fabric is less than 40 wt %.
4. The thermally-conductive material according to claim 1, wherein
the textile fabric comprises fibers comprising a hydrophilic fiber
material.
5. The thermally-conductive material according to claim 1, wherein
the thermally-conductive coating comprises a pattern on the textile
fabric.
6. The thermally-conductive material according to claim 5, wherein
the pattern at least partially has continuous lines.
7. The thermally-conductive material according to claim 1, wherein
a coating weight of the thermally-conductive coating is 1 to 50
g/m.sup.2.
8. The thermally-conductive material according to claim 1, wherein
the graphite comprises graphite in particle form, with an average
particle size of 0.5 to 10 .mu.m.
9. The thermally-conductive material according to claim 1, wherein
the thermally-conductive material has a degree of sound absorption,
measured in an impedance tube at 1,600 Hz, of more than 0.55.
10. The thermally-conductive material according to claim 1, wherein
the textile fabric has a proportion of at least 30 wt % of
cellulose fibers, relative to a total amount of fibrous material in
the textile fabric.
11. The thermally-conductive material according to claim 1, wherein
the textile fabric comprises glass fibers in a proportion of 5 to
80 wt % relative to a total amount of fibrous material in the
textile fabric.
12. The thermally-conductive material according to claim 1, wherein
the textile fabric comprises a wet-laid nonwoven or a carded
nonwoven.
13. The thermally-conductive material according to claim 1, wherein
the thermally-conductive material has a basis weight of 20 to 100
g/m.sup.2, and/or a thickness of 0.1 to 0.5 mm, and/or an air
permeability of 100 to 3,000 L/m.sup.2/s.
14. The thermally-conductive material according to claim 1, further
comprising a hot-melt adhesive comprising an adhesive material
coating.
15. A method of using the thermally-conductive material according
to claim 1, comprising: providing the thermally-conductive material
for thermal conduction and simultaneous sound absorption in ceiling
and/or wall elements.
16. The thermally-conductive material according to claim 1, wherein
the thermally-conductive material has a flow resistance of 100
Pa*s/m to 300 Pa*s/m.
17. The thermally-conductive material according to claim 16,
wherein the thermally-conductive material has a flow resistance of
120 Pa*s/m to 250 Pa*s/m.
18. The thermally-conductive material according to claim 14,
wherein the adhesive material coating is discontinuous.
19. The method according to claim 15, wherein the ceiling and/or
wall elements comprise a frame that is fastenable to a ceiling
and/or a wall, the frame having a base in which a heating and/or
cooling element is arranged.
Description
CROSS-REFERENCE TO PRIOR APPLICATION
[0001] Priority is claimed to German Patent Application No. DE 10
2018 120 713.1, filed on Aug. 24, 2018, the entire disclosure of
which is hereby incorporated by reference herein.
FIELD
[0002] The invention relates to a thermally-conductive material
which simultaneously has effective sound absorption properties, and
to its use.
BACKGROUND
[0003] Particularly in modern buildings, it is often desirable to
air condition the rooms of the building by removing heat from or
supplying heat to the building, even in moderate climate zones.
Heat dissipation is important in particular for rooms that are much
frequented by people and/or equipped with numerous electronic
appliances, since these have a significant heat output within the
triple-digit watt range. The same applies, for example, to
production halls, where machines and installations emit
considerable amounts of heat which must be removed from the
building.
[0004] In principle, there are different possibilities for heat
removal, wherein extensive air-conditioning elements based upon the
heat radiation principle have proven to be particularly suitable.
For air conditioning rooms--in particular, for room
cooling--thermal conduction devices or air-conditioning elements
known from the prior art are used. Such air-conditioning elements
are also suitable, in principle, for room heating by reversing the
direction of thermal conduction.
[0005] The prior art already discloses ceiling or wall elements
that have a frame, which can be fastened to the ceiling or the
wall, with a base plate and a heating or cooling register arranged
in the frame. DE 20 2007 010 215 U1, for example, discloses a wall
or ceiling covering with a heating or cooling register in the form
of pipelines which are fastened to thermally-conductive profiles.
The thermally-conductive profiles rest on the rear side of a
covering surface formed by covering panels. The covering panels are
fastened to support rails having a U-shaped cross-section. The
support rails and the covering panels attached thereto thus form a
frame which can be fastened to a ceiling or wall and has a base
formed by the covering panels. The thermally-conductive profiles
are arranged in the interior of this frame and adjoin the covering
panels. The thermally-conductive profiles and the pipelines
attached thereto form the heating or cooling register. In order to
produce an effective thermal conduction contact between the
pipelines and the covering surface, retainers are arranged
transversely to the elongated, thermally-conductive profiles and
hold at least two adjacent, thermally-conductive profiles against
the covering panel under spring tension.
[0006] On their rear side, the thermally-conductive profiles have
an approximately semicircular extension in which the pipelines are
arranged. Depending upon the intended use as heating or cooling
lines, a heating or cooling medium flows through the pipelines,
such as, for example, fresh or cold water. The thermally-conductive
profiles are generally made of metal--for example, aluminum. The
covering panels can, for example, be gypsum board panels or
perforated metal tiles made of steel or aluminum.
[0007] In order to enable a more efficient thermal conduction
between the heating or cooling register and the space to be heated
or cooled, DE 10 2009 055 440 A1 proposes a ceiling or wall element
for fastening to a ceiling or a wall, wherein the ceiling or wall
element has a frame, which can be fastened to the ceiling (or the
wall), with a base in which a heating or cooling register is
arranged, and wherein a fleece and a graphite film is arranged
between the base of the frame and the heating or cooling register.
The perforated graphite film is intended to ensure good thermal
contact between the heating or cooling register and the bottom
panel of the ceiling or wall element, and the fleece is intended to
improve the sound absorption of the covering or wall element. In
the case of the fleece, a carbon fiber fleece is shown as being
preferred, since this has a high thermal conductivity. Preferably,
the fleece and the perforated graphite film disposed thereon are a
composite which can be produced by calendering.
[0008] A disadvantage of the thermally-conductive material
described is that the thermal conduction in a vertical direction
must be done via the carbon fiber fleece, since the graphite film
only allows a planar heat conduction. Carbon fiber fleeces are,
however, undesirable for health reasons in building applications
and are unattractive in terms of price. Moreover, the use of a film
has the disadvantage that it must be perforated in order to be
sound-permeable and acoustically effective. As a result, films
quickly tear and are brittle.
[0009] EP 2 468 974 A2 is also based upon the aim of achieving an
improvement in the thermal conduction of heating or cooling
elements. For this purpose, this publication proposes a
construction for a heating or cooling element--in particular, for
an air-conditioning ceiling--comprising a perforated,
thermally-conductive carrier panel, on the rear side of which lines
of a heating or cooling register run, which are in
thermally-conductive contact with the carrier panel, wherein the
rear side of the carrier panel and the heating or cooling lines are
covered by a cover sheet which has a textile or lattice-like
structure and consists of a thermally-conductive material or is
coated with a thermally-conductive material.
[0010] A fleece consisting of graphite or coated with graphite can
be used, for example, as the covering web. This fleece has no
particular acoustic properties. Therefore, in order to improve
acoustics, it is proposed to additionally laminate an acoustic
nonwoven onto the rear side of the cover sheet.
[0011] EP 2 191 058 B1 describes a layer, for use in a metal
ceiling, with a basis weight of at most 45 g/m.sup.2, comprising a
fiber mixture, which is present in a proportion of at most 30
g/m.sup.2, and a flame retardant which is present in a proportion
of at most 10 g/m.sup.2. The layer exhibits good acoustic
properties, since it has a high and defined porosity. Owing to its
high porosity, the layer is, however, only suitable to a limited
extent for applications in which the thermal conduction is in the
foreground.
SUMMARY
[0012] In an embodiment, the present invention provides a
thermally-conductive material, comprising: a textile fabric; and a
graphite-containing, thermally-conductive coating, in which
graphite is present in a proportion of 5 wt % to 50 wt % relative
to a total weight of the thermally-conductive material, wherein the
thermally-conductive material has a flow resistance of 60 Pa*s/m to
400 Pa*s/m.
DETAILED DESCRIPTION
[0013] In an embodiment, an aim of the invention is to provide a
material which, with a simple design, combines very good thermal
conduction properties with very good acoustic properties and can
therefore be used for thermal conduction and sound absorption--for
example, in the above-mentioned thermal conduction devices.
[0014] This aim is achieved by a thermally-conductive material with
a flow resistance of 60 Pa*s/m to 400 Pa*s/m--more preferably, of
100 Pa*s/m to 300 Pa*s/m, and, even more preferably, of 120 Pa*s/m
to 250 Pa*s/m--which has a textile fabric and a
graphite-containing, thermally-conductive coating, wherein the
graphite is present in a proportion of 5 wt % to 50 wt %, relative
to the total weight of the thermally-conductive material.
[0015] Surprisingly, it has been found that, with the
thermally-conductive material according to the invention, very good
thermal conduction properties can be combined with very good
acoustic properties. The thermally-conductive material can have a
very simple and thin construction.
[0016] In a preferred embodiment, the proportion of graphite with
respect to the thermally-conductive coating is more than 50 wt %,
e.g., 50 to 100 wt %--preferably, 60 to 100 wt %, more preferably,
70 to 100 wt %, and, even more preferably, 80 to 100 wt %. This is
advantageous, since the thermal conduction properties of the
textile fabric can be significantly improved in this way.
Accordingly, good thermal conductivity can thus also be realized
with small application amounts. Small application amounts are in
turn advantageous, since this influences the porosity and the air
permeability of the textile fabric less.
[0017] In contrast, thermally-conductive coatings of textile
fabrics known from the prior art usually have a smaller amount of
graphite, since the graphite layer generally contains more than 50
wt % binder.
[0018] The advantage of using a thermally-conductive coating in
comparison to films is that they can at least partially penetrate
into the textile material. The advantage of penetrating the
material is that the thermal conduction in the direction of the
surface normals is improved. Accordingly, in a preferred
embodiment, the thermally-conductive coating at least partially
penetrates into the textile fabric.
[0019] An advantage of the thermally-conductive coating over
perforated metal sheets is that improved adhesiveness can be
achieved due to the faster and more uniform distribution of heat in
the textile fabric that it makes possible.
[0020] In a preferred embodiment of the invention, adjusting the
high proportion of graphite in the thermally-conductive coating is
achieved by the textile fabric having fibers of a hydrophilic
fibrous material. Without specifying a mechanism, it is assumed
that the hydrophilic fiber material has a high affinity and,
associated therewith, a particularly good adhesion to the graphite.
This makes it possible to keep the proportion of binder very low in
the thermally-conductive coating and/or between the
thermally-conductive coating and the textile fabric.
[0021] Nevertheless, the thermally-conductive coating may contain
binders. Exemplary binders are polymer binders from the group of
acrylates, vinyl acrylates, vinyl acetates, ethylene vinyl acetates
(EVA), acrylonitrile butadiene (NBR), styrene butadienes (SBR),
acrylonitrile butadiene styrenes (ABS), vinyl chlorides, ethylene
vinyl chlorides, polyvinyl alcohols, polyurethanes, starch
derivatives, cellulose derivatives, and mixtures and/or copolymers
thereof. In a preferred embodiment of the invention, the proportion
of polymer binder, and in particular of the aforementioned polymer
binders, in the thermally-conductive coating and/or between the
thermally-conductive coating and the textile fabric is less than 50
wt %, e.g., 1 to 50 wt %--preferably, less than 40 wt %, e.g., 1 to
40 wt %, more preferably, less than 30 wt %, e.g., 1 to 30 wt %,
and, in particular, less than 20 wt %, e.g., 1 to 20 wt %. The
advantage of using only a slight proportion of polymer binder or
entirely dispensing with it is an improved burning behavior of the
material in case of a fire, and improved acoustic properties.
[0022] In a preferred embodiment of the invention, the proportion
of graphite relative to the total weight of the
thermally-conductive material is 10 wt % to 50 wt %--preferably, 10
wt % to 35 wt %, and, even more preferably, 10 wt % to 20 wt %.
[0023] In a further preferred embodiment of the invention, the
thermally-conductive coating is present in the form of a pattern on
the textile fabric. This means that regions of the surface of the
textile fabric are covered with the thermally-conductive coating,
and other areas are not. The thermally-conductive coating may also
at least partially penetrate into the textile fabric. The advantage
of forming a pattern is that the covered regions provide the
thermally-conductive material with a high thermal conductivity,
while the uncovered regions are particularly active acoustically,
since their porosity is not reduced by being furnished with the
thermally-conductive coating. The pattern may be a geometric or an
irregular pattern. The degree of surface coverage of the
thermally-conductive coating with respect to the surface of the
thermally-conductive material is, advantageously, 1 to 95%,
preferably 10 to 60%, and, particularly preferably, 30 to 50%. In a
preferred embodiment, the pattern at least partially has continuous
lines--preferably, with a line width >0.5 mm, preferably 2.0 to
10.0 mm, and, particularly preferably, 4.0 to 7.0 mm. A good
thermal conductivity in the surface of the thermally-conductive
material can be achieved by the penetrability.
[0024] In a further preferred embodiment, the pattern at least
partially has discrete points, rods, and/or non-continuous
areas--preferably, with a size of <100 mm.sup.2, more
preferably, 1.0 to 50 mm.sup.2, and, in particular, 2.0 to 10
mm.sup.2. Practical tests have shown that this leads to rapid
thermal conduction through the thickness of the material, i.e.,
perpendicular to the plane of the textile fabric.
[0025] The thermally-conductive material according to the invention
is further distinguished by excellent acoustic properties. Thus,
the thermally-conductive material has a flow resistance of 60
Pa*s/m to 400 Pa*s/m--more preferably, 100 Pa*s/m to 300 Pa*s/m,
and, even more preferably, 120 Pa*s/m to 250 Pa*s/m. The flow
resistance is measured in accordance with DIN EN 29053-A: 1993-05.
The negative influence of the thermally-conductive coating on the
acoustic properties of the material is reduced by reducing the
proportion of the polymer binder or by entirely dispensing with it.
Completely sealing the surface can thus be prevented, so that
sufficient porosity is maintained for acoustic effectiveness. The
flow resistance can be adjusted in a manner known to the person
skilled in the art, e.g., by suitably selecting the fiber materials
in coordination with the selected parameters in the production and
coating of the textile fabric. It has been found that particularly
good sound absorption is achievable with the selected flow
resistances according to the invention. The degree of sound
absorption .alpha.(0) of the thermally-conductive material
according to the invention, measured in the impedance tube at 1,600
Hz, is preferably more than 0.55, e.g., 0.55 to 1.0, more
preferably greater than 0.60, e.g., 0.6 to 1.0, and, in particular,
more than 0.65, e.g., 0.65 to 1.0. The degree of sound absorption
is determined in accordance with DIN EN ISO 10534-1: 2001-10 with
the parameters given in Example 2.
[0026] According to the invention, the textile fabric preferably
contains fibers selected from the group consisting of glass fibers,
polyolefins, polyesters--in particular, polyethylene terephthalate,
polybutylene terephthalate; polyamide--in particular, polyamide 6.6
(Nylon.RTM.), polyamide 6.0 (Perlon.RTM.), aramide, wool, cotton,
silk, hemp, bamboo, kenaf, sisal, cellulose, soy, flax, glass,
basalt, carbon, viscose and mixtures thereof. According to the
invention, the fiber material particularly preferably contains
glass fibers, cellulose and/or mixtures thereof--in particular,
glass fibers and cellulose.
[0027] The textile fabric may also contain conductive fibers, such
as metal fibers, ceramic fibers, carbon fibers, etc., to further
improve thermal conductivity.
[0028] Cellulose fibers are particularly preferred according to the
invention. Cellulose fibers are to be understood as fibers having
cellulose, viscose, and/or fine-fiber or fibrillated cellulose
components--so-called fiber pulp or cellulose. The fibers,
particularly preferably, substantially consist of the
aforementioned components, i.e., their proportion is more than 80
wt %.
[0029] In a preferred embodiment of the invention, the textile
fabric contains a proportion of at least 30 wt %, e.g., 30 to 100
wt % and/or 30 to 95 wt %--preferably, 50 to 100 wt % and/or 50 to
90 wt %, more preferably, 60 to 95 wt %, and, in particular, 65 to
85 wt %--of cellulose fibers, relative in each case to the total
amount of fibrous material in the textile fabric.
[0030] In a further preferred embodiment of the invention, the
textile fabric contains glass fibers--preferably, in an amount of 5
to 80 wt %, more preferably, 5 to 70 wt %, more preferably, 10 to
60 wt %, in particular, 20 to 40 wt %--respectively relative to the
total amount of fibrous material in the textile fabric. By adding
glass fibers, the textile fabric can be provided with particularly
high structural stability and low thermal shrinkage.
[0031] Most preferably, the textile fabric contains cellulose
fibers--preferably, in a proportion of 30 to 95 wt %, more
preferably 50 to 90 wt %, in particular, 65 to 85 wt %--and glass
fibers--preferably, in a proportion of 5 to 70 wt %, more
preferably, 10 to 50 wt %, in particular, 15 to 35 wt
%--respectively relative to the total amount of fibrous material in
the textile fabric.
[0032] The textile fabric could be in the form of fleece, nonwoven,
or paper. A nonwoven, such as DIN EN ISO 9092, is preferably used
according to the invention.
[0033] To produce the nonwoven, a nonwoven can be laid dry in a
carding process, a wet-laid, nonwoven process, or in a spun-bonded,
nonwoven process, in a manner known to the person skilled in the
art. Preferably, the nonwoven is laid in a wet-laid, nonwoven
process or carding process. A particularly high degree of
uniformity can thereby be achieved, which is decisive for the
acoustic properties. Accordingly, the nonwoven is preferably a
wet-laid nonwoven or a carded nonwoven. The nonwoven is
particularly preferably laid in a wet-laid, nonwoven process--in
particular, with an oblique screen--since it is thereby possible to
obtain nonwovens with particularly high uniformity.
[0034] The fiber mixture in the wet-laid, nonwoven process could
also have fine fibrous or fibrillated cellulose
components--so-called fiber pulp or cellulose. These components
allow very effective harmonization of the acoustic effectiveness of
the textile fabric. In a preferred embodiment, the nonwoven is thus
a wet-laid nonwoven which contains fiber pulp--in particular,
cellulose pulp--and/or cellulose--preferably, in a proportion of at
least 30 wt %, e.g., 30 to 100 wt % and/or 30 to 95 wt %,
preferably, 50 to 100 wt % and/or 50 to 90 wt %, more preferably,
60 to 95 wt %, and, in particular, 65 to 85 wt %--respectively
relative to the total amount of fibrous material in the wet-laid
nonwoven.
[0035] Against this background, it is conceivable that the wet-laid
nonwoven contains two or more different types of fiber pulp and/or
cellulose which differ in terms of their fineness. As a result, a
particularly precise setting of the porosity is attainable and,
associated therewith, a textile fabric with a particularly
effective acoustic flow resistance. It is also conceivable for the
wet-laid nonwoven to contain finely-ground, synthetic pulps--for
example, of viscose, polyolefin, and/or aramide fibers.
[0036] The fleece can, in a known manner, be solidified
mechanically, chemically, and/or thermally to form the nonwoven.
Chemical bonding with the aid of a polymer binder is particularly
preferred. Preferred fiber binders are polyacrylates, polyvinyl
acrylates, polystyrene acrylates, polyvinyl acetates, polyethylene
vinyl acetates (EVA), acrylonitrile butadiene rubber (NBR), styrene
butadiene rubber (SBR), acrylonitrile butadiene styrene rubber
(ABS), polyvinyl chlorides, polyvinyl ethylene vinyl chlorides,
polyvinyl alcohols, polyurethanes, starch derivatives, cellulose
derivatives, and copolymers and/or mixtures thereof. Accordingly,
the nonwoven is preferably a chemically-bonded nonwoven. The fiber
binder can be used to obtain the textile fabric with a high
strength and good aging resistance. The application of the fiber
binder can be carried out by impregnation, spraying, or by means of
otherwise customary application methods.
[0037] The fiber binder can additionally contain customary
additives such as a flame retardant, e.g., metal hydroxides such as
aluminum hydroxide, diammonium hydrogen phosphate or other nitrogen
and/or phosphorus-based flame retardants, such as ammonium
polyphosphates or nitrogen-containing phosphoric acid salts. This
can also be introduced into the impregnation mixture for fiber
bonding via the fiber binder.
[0038] The proportion of fiber binder including the additives in
the thermally-conductive material is preferably 10 to 70 wt %, more
preferably, 20 to 50 wt %, and, in particular, 30 to 40 wt %,
relative to the total weight of the thermally-conductive
material.
[0039] The textile fabric can additionally contain anti-corrosive
agents; this is because condensation moisture when using the
cooling lid can in fact lead to damage of the metal elements, e.g.,
aluminum profiles, etc. The addition of an anti-corrosive agent can
counteract this.
[0040] In addition, the textile fabric can be provided with an
antimicrobial finish with the aid of a biocidal additive. In fact,
condensation moisture during use can lead to bacteria and fungi
growth in the textile fabric, which can be prevented by such
finishing.
[0041] The basis weight of the thermally-conductive material is
preferably 20 to 100 g/m.sup.2, more preferably, 40 to 70
g/m.sup.2, and, in particular, 45 to 60 g/m.sup.2, in each case
measured according to ISO 9073-1. A material with low basis
weights, i.e., a low use of material, is recommended for good fire
behavior and good acoustic properties.
[0042] The thickness of the thermally-conductive material is
preferably 0.1 to 0.5 mm, more preferably, 0.15 to 0.4 mm, and, in
particular, 0.2 to 0.3 mm, measured in each case according to ISO
9073-2. An advantage of a thin material which at the same time has
good acoustic properties is that the processing, i.e., lamination
of the material in perforated metal covers, is facilitated.
[0043] The air permeability of the thermally-conductive material is
preferably 100 to 3,000 L/m.sup.2/s, more preferably, 200 to 1,000
L/m.sup.2/s, and, in particular, 300 to 700 L/m.sup.2/s, measured
in each case in accordance with DIN EN ISO 9237 at 100 Pa air
pressure. These air permeabilities result in particularly good
acoustic properties.
[0044] The tensile strength in at least one direction--preferably
in the machine direction--of the thermally-conductive material is
preferably 20 to 300 N/5 cm, more preferably 30 to 150 N/5 cm, and,
in particular, 50 to 100 N/5 cm, measured in each case according to
ISO 9073 to 3.
[0045] In a preferred embodiment of the invention, the textile
fabric is metallized. The metallization can be effected, for
example, by a vacuum deposition process or electrochemical
deposition (electroplating). Aluminum, copper, copper alloys,
stainless steel, gold, and/or silver have proven to be particularly
suitable metals. Special preference is given to finishing with
stainless steel, since this gives the textile fabric a particularly
high aging resistance. In addition, finishing with a
corrosion-inhibiting agent can take place.
[0046] According to the invention, the thermally-conductive
material has a graphite-containing, thermally-conductive coating.
In addition to graphite in the narrower sense, "graphite" is also
to be understood according to the invention as graphite-analogous
compounds such as, in particular, expanded graphite, graphene, and
hexagonal boron nitride. In a preferred embodiment, the graphite is
selected from graphite in the form of a material having several
crystal planes and graphene, i.e., a material having only a single
crystal plane. The graphite is preferably in particulate form. The
average size of the graphite particles can preferably be 0.5 to 10
micrometers--particularly preferably, 1 to 3 micrometers. Practical
tests have shown that this results in a good compromise between
processability and thermal conductivity. Large graphite particles
are advantageous for good thermal conduction, but are, however,
more difficult to process, and preferably remain on the surface of
the textile fabric. This leads to a low penetration depth of the
graphite into the thermally-conductive material, which leads to a
reduced conductivity perpendicular to the surface plane.
[0047] In one embodiment of the invention, the coating weight of
the thermally-conductive coating is 1 to 50 g/m.sup.2--preferably,
2 to 30 g/m.sup.2, and, more preferably, 5 to 15 g/m.sup.2.
Practical tests have shown that, even with a low graphite coating
weight, a significant improvement in the thermal conductivity can
be observed. At the same time, good acoustic properties can be
achieved, since the porosity of the material is maintained.
[0048] The thermally-conductive coating is preferably applied by
finishing the textile fabric with an aqueous graphite dispersion
and then drying it.
[0049] A binder, e.g., a polymer binder, may be added to the
graphite dispersion in order to improve the bonding of the textile
fabric, e.g., polyacrylates, polyvinyl acrylates, polyvinyl
acetates, polyethylene vinyl acetates (EVA), acrylonitrile
butadiene (NBR), styrene butadienes (SBR), vinyl chlorides,
ethylene vinyl chlorides, polyvinyl alcohols, polyurethanes, starch
derivatives, cellulose derivatives, and mixtures and/or copolymers
thereof.
[0050] Further additives may be added to the graphite dispersion,
e.g., defoamers, wetting agents, surfactants which facilitate
processing, bases and/or acids for adjusting the pH, flame
retardants, corrosion inhibitors, and/or biocides. A wetting agent
is preferably selected from the group consisting of: glycerin,
propylene glycol, sorbitol, trihydroxystearine, phospholipids,
ethylene oxide/fat alcohol ethers, ethoxylates of propylene oxide
with propylene glycol, esters of sorbitol and/or of glycerol,
alkylsulfonates, alkylsulfosuccinates and docusates and mixtures
thereof.
[0051] Practical tests have shown that when a proportion of the
wetting agent relative to the total amount of the graphite
dispersion is in the range of 0.1 to 5 wt %--preferably 1 to 4 wt
%, and, in particular, 1.5 to 3.5 wt %--a particularly uniform and
homogeneous wetting and particularly good penetration into the
material take place.
[0052] Furnishing can be carried out by all customary finishing
methods for fabrics, e.g., by impregnation, e.g., by means of
Foulard; by printing, e.g., flat or screen printing, rotary stencil
printing; kiss coating, doctor blade, etc.; and spraying; the
finishing can take place on one side or on both sides. Coating,
e.g., printing--in particular, in screen printing or rotary stencil
printing--is particularly preferred. The thermally-conductive
coating can thus be applied, for example, as a pattern print to the
textile fabric. The thermally-conductive material then has a high
thermal conductivity locally in the printed region, while the
unprinted regions are acoustically particularly active, since their
porosity is not impaired by a finish with the thermally-conductive
coating. The degree of surface coating of the thermally-conductive
material by the thermally-conductive coating in the form of a
pattern is preferably 1 to 100%, preferably 10 to 60%, and,
particularly preferably, 30 to 50%. In a preferred embodiment, the
printing is carried out at least partially in the form of
continuous lines--preferably with a line width of >0.5 mm,
preferably of 2.0 to 10.0 mm, and, particularly preferably, of 4.0
to 7.0 mm. This causes a rapid distribution of the heat in the
plane of the textile fabric.
[0053] In a further preferred embodiment, the printing can take
place at least partially in the form of discrete dots, rods, and/or
non-continuous surfaces--preferably with a size of <100
mm.sup.2, particularly preferably of 1.0 to 50 mm.sup.2, and, in
particular, of 2.0 to 10 mm.sup.2. Practical tests have shown that
this leads to rapid thermal conduction through the thickness of the
material, i.e., perpendicular to the plane of the textile
fabric.
[0054] Drying can be carried out by all customary drying methods,
e.g., contact drying with a roller drier; circulating air or
through-air drying with a belt dryer; IR or microwave drying, etc.
Through-air drying is preferred in order to maintain the porosity
of the material and thus the good acoustic properties. The material
can additionally be post-treated by compression rolling in order to
further improve the contact of the graphite particles with one
another and thus the thermal conductivity of the material.
[0055] In a preferred embodiment of the invention, the
thermally-conductive material has an additional, preferably
discontinuous, adhesive material coating. The adhesive material
coating preferably consists of a hot-melt adhesive. The
discontinuous nature of the adhesive material coating is
advantageous in that it does not substantially impair the acoustic
effectiveness of the thermally-conductive material. The adhesive
coating can be applied, for example, by scattering a hot-melt
adhesive powder onto the thermally-conductive material and then
thermally fixing the powder to the thermally-conductive material.
The hot-melt adhesive advantageously has a melting point of <125
C.degree..
[0056] The basis weight of the adhesive material coating is
preferably 5 to 50 g/m.sup.2, more preferably 10 to 40 g/m.sup.2,
and, especially preferably, 12 to 25 g/m.sup.2.
[0057] The adhesive material coating preferably substantially
consists of a thermoplastic polymer, e.g., a largely amorphous
polyester or copolyester, a polyamide or copolyamide, a
polyurethane, a polyolefin, polyethylene vinyl acetate and/or
mixtures, copolymers or terpolymers thereof. In this case,
"substantially" is a proportion of at least 70 wt %--preferably
more than 80 wt %--relative to the total mass of the adhesive
material coating.
[0058] The adhesive material coating can additionally be furnished
with thermally-conductive additives, e.g., by compounding the
thermoplastic polymer with thermally-conductive fillers (for
example, carbon black, graphite, metal powders, metal oxides, boron
nitride, ceramic compounds, etc.) in order to further increase the
thermal conductivity of the thermally-conductive material according
to the invention.
[0059] If the adhesive material coating is applied to the textile
fabric in the form of a powder, the powder can be processed as a
mixture with other thermally-conductive powders (for example, metal
powders, fine metal spheres, metal oxide powders, ceramic powders,
etc.) in order to further increase the thermal conductivity of the
thermally-conductive material. The adhesive material coating can
also contain a ceramic reactive adhesive which has, for example,
reactive silane groups.
[0060] The thermally-conductive material according to the invention
is outstandingly suitable for thermal conduction and simultaneous
sound absorption in ceiling and/or wall elements--in particular,
comprising a frame which can be fastened to the ceiling and/or the
wall and has a base in which a heating and/or cooling element is
arranged. The thermally-conductive material according to the
invention is preferably arranged between the base of the frame and
the heating or cooling element.
[0061] The ceiling and/or wall elements may be used in suspended,
perforated, and/or slotted metal ceiling and/or wall systems (inter
alia, also in wood or gypsum board ceilings). It is also
conceivable to use the thermally-conductive material according to
the invention in the construction of raised floors.
[0062] The invention is explained in more detail below with
reference to several examples.
Example 1: Production of a Thermally-Conductive Material According
to the Invention
[0063] For the production of a thermally-conductive material
according to the invention, first, a textile fabric is produced in
the form of a wet-laid nonwoven. The overall basis weight of the
wet-laid nonwoven is 48 g/m.sup.2. In this case, the textile fabric
has a fiber mixture of 70 wt % cellulose and 30 wt % glass fibers.
The fiber mixture contributes a total of 25 g/m.sup.2 to the basis
weight of the textile fabric. The textile fabric further has a
fiber binder consisting of polyacrylate binder and flame retardant
that contributes 23 g/m.sup.2 to the basis weight.
[0064] A commercially available graphite dispersion having an
average particle diameter of 2.5 micrometers and a solids content
of 18 wt % is used to produce the thermally-conductive coating.
Application takes place by means of rotary stencil printing and
drying in a flow-through oven. A rectangular diamond pattern is
selected as a template pattern. The average width of the printed
lines on the wet-laid nonwoven is 5.0 mm, and the surface coverage
by the thermally-conductive coating is 52%. The proportion of
graphite in the thermally-conductive coating, measured according to
Example 4, is 80 wt %, which corresponds to a proportion of 14 wt
%, relative to the total weight of the thermally-conductive
material.
[0065] The resulting thermally-conductive material has a total
weight of 57 g/m.sup.2, a thickness of 0.23 mm, a tensile strength
in the machine direction of 65 N/5 cm, an air permeability at 100
Pa of 550 L/m.sup.2/s, and a flow resistance of 190 Pa*s/m.
Example 2: Determining the Degree of Sound Absorption of the
Thermally-Conductive Material
[0066] The thermally-conductive material was furnished with an
adhesive material coating for tests in the impedance tube. The
adhesive material consists of epsilon polycaprolactone, which is
powdered onto the thermally-conductive material as ground powder
having an average grain size of 150 micrometers and sintered in the
furnace. The applied amount is 15 g/m.sup.2 in this case.
[0067] The thermally-conductive material furnished with the
adhesive material coating is then ironed onto a perforated, painted
steel sheet with a thickness of 0.5 mm, a proportion of perforated
surface of 15%, and a perforation diameter of 2.3 mm. The degree of
sound absorption on the composite material is determined, and
.alpha.(0) specified at a frequency of 1,600 Hz.
[0068] At 1,600 Hz, a degree of sound absorption of .alpha.(0)=0.7
is determined.
Example 3: Determination of the Thermal Conductivity of the
Thermally-Conductive Material
[0069] The thermal conductivity of the thermally-conductive
material was investigated in comparison with the textile fabric
without a thermally-conductive coating. The measurements were
carried out by the plate method in accordance with DIN 52612 on 6
stacked test specimens, and according to the hot disk method with a
single layer pursuant to ISO 22007-2.2:2008, Part 2.
TABLE-US-00001 Thermal-conductivity Textile Thermally-conductive
method Unit fabric material Plate method W/(K * m) 0.06 0.08 Hot
disk W/(K * m) 0.06 0.09
Example 4: Qualitative and Quantitative Determination of the
Graphite
[0070] A qualitative identification of the graphite was performed
by means of x-ray diffraction (XRD) pursuant to DIN EN 13925-2
2003-07. For this purpose, X-ray diffractograms of the
thermally-conductive material were recorded with CoK.alpha.
radiation at 40 kV and 35 mA within an angular range of 5.degree.
to 60.degree. (2 theta). A unique identification can be made by the
sharp reflections at 30.78.degree. (3.37 .ANG.); 49.69.degree.
(2.13 .ANG.); 52.19.degree. (2.04 .ANG.); 64.37.degree. (1.68
.ANG.); 93.21.degree. (1.23 .ANG.). A quantitative determination of
the proportion of graphite in the thermally-conductive material or
the thermally-conductive coating can be carried out by means of
thermogravimetric analysis (TGA) according to DIN EN ISO 11358
2014-10. The sample is first heated in an inert nitrogen atmosphere
to 1,000.degree. C. and cooled back down to 300.degree. C. This is
followed by heating the sample again to 1,000.degree. C. under
oxygen. In this last combustion stage, the graphite and (if
available) the carbon black are burned. In this case, carbon black
burns within a temperature range of 380.degree. C. to 700.degree.
C., and graphite burns at temperatures greater than 700.degree. C.
If the combustion of the carbon black is not completely separated
from that of the graphite, the derivation of the thermogravimetry
curve, which then shows a reversal point at 700.degree. C., is used
to determine the temperature ranges to be evaluated.
[0071] While the invention has been illustrated and described in
detail in the drawings and foregoing description, such illustration
and description are to be considered illustrative or exemplary and
not restrictive. It will be understood that changes and
modifications may be made by those of ordinary skill within the
scope of the following claims. In particular, the present invention
covers further embodiments with any combination of features from
different embodiments described above and below. Additionally,
statements made herein characterizing the invention refer to an
embodiment of the invention and not necessarily all
embodiments.
[0072] The terms used in the claims should be construed to have the
broadest reasonable interpretation consistent with the foregoing
description. For example, the use of the article "a" or "the" in
introducing an element should not be interpreted as being exclusive
of a plurality of elements. Likewise, the recitation of "or" should
be interpreted as being inclusive, such that the recitation of "A
or B" is not exclusive of "A and B," unless it is clear from the
context or the foregoing description that only one of A and B is
intended. Further, the recitation of "at least one of A, B and C"
should be interpreted as one or more of a group of elements
consisting of A, B and C, and should not be interpreted as
requiring at least one of each of the listed elements A, B and C,
regardless of whether A, B and C are related as categories or
otherwise. Moreover, the recitation of "A, B and/or C" or "at least
one of A, B or C" should be interpreted as including any singular
entity from the listed elements, e.g., A, any subset from the
listed elements, e.g., A and B, or the entire list of elements A, B
and C.
* * * * *