U.S. patent application number 10/593155 was filed with the patent office on 2007-07-12 for heat-protected thermoplastic component, particularly a vehicle underside component with integrated heat-protection.
Invention is credited to Hermann De Ciutiis, Alexander Wildhaber.
Application Number | 20070160864 10/593155 |
Document ID | / |
Family ID | 32695388 |
Filed Date | 2007-07-12 |
United States Patent
Application |
20070160864 |
Kind Code |
A1 |
De Ciutiis; Hermann ; et
al. |
July 12, 2007 |
Heat-protected thermoplastic component, particularly a vehicle
underside component with integrated heat-protection
Abstract
A component for use in thermally stressed areas of vehicles,
e.g. in the area of the engine compartment underside, comprises a
thermoplastic part i.e. a supporting layer (2) that is thermally
protected by a metallic foil (3). In order to improve the adherence
of the metallic foil (3), the metallic foil (3) is provided with a
multitude of folding pockets (4) anchored in the thermoplastic
material of the supporting layer (2). This creates a positive
connection between the metallic foil (3) and the supporting layer
(2).
Inventors: |
De Ciutiis; Hermann;
(Winterthur, CH) ; Wildhaber; Alexander;
(Walenstadt, CH) |
Correspondence
Address: |
NATH & ASSOCIATES
112 South West Street
Alexandria
VA
22314
US
|
Family ID: |
32695388 |
Appl. No.: |
10/593155 |
Filed: |
March 18, 2005 |
PCT Filed: |
March 18, 2005 |
PCT NO: |
PCT/CH05/00164 |
371 Date: |
October 31, 2006 |
Current U.S.
Class: |
428/606 ;
428/920 |
Current CPC
Class: |
Y10T 428/12431 20150115;
B62D 29/001 20130101; B60R 13/0861 20130101; B62D 25/20 20130101;
B62D 25/2072 20130101; B62D 29/005 20130101 |
Class at
Publication: |
428/606 ;
428/920 |
International
Class: |
B21C 37/00 20060101
B21C037/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 19, 2004 |
DE |
20 2004 004 366.1 |
Claims
1. Heat-protected thermoplastic component (1) having a carrier
layer (2) made of a thermoplastic synthetic and an at least
partially connected metallic foil (3), wherein said foil (3)
comprises a plurality of folding pockets (4), which are embedded in
the carrier layer (2) and form a positive connection with the
carrier layer (2).
2. Component according to claim 1, wherein the thermoplastic
synthetic is an endless fiber reinforced thermoplast (LFT).
3. Component according to claim 1, wherein the thermoplastic
synthetic is a glass fiber reinforced synthetic (GMT).
4. Component according to claim 1, wherein the metallic foil (3) is
an aluminium foil.
5. Component according to claim 4, wherein the aluminium foil has a
thickness of 0.01 to 0.1 mm.
6. Component according to claim 1, wherein in a sector of 10 to 30
mm there are arrayed at least 1 to 5 folding pockets.
7. Component according to claim 1, wherein, between the metallic
foil (3) and the thermoplastic carrier layer (2) there is provided
a hotmelt adhesive.
8. Component according to claim 1, wherein the peeling resistance
W.sub.s, after a constant exposure over more than 1000 hours to
temperatures of about 140.degree. C., has a value of at least 0.15
N/mm.sup.2.
9. Component according to claim 1, wherein the peeling resistance
W.sub.s, after a constant exposure over more than 1000 hours to
temperatures of about 140.degree. C., is reduced by no more than
20%.
10. Component according to claim 1, wherein said component is a
vehicle underside component.
Description
[0001] The present invention concerns a heat-protected
thermoplastic component according to the preamble of claim 1, and
in particular a vehicle underside component with integrated
heat-protection.
[0002] Thermoplastic materials such as polypropylene are sensitive
to temperature and have a high surface emission potential, or they
have an increased heat radiation absorption capacity. This
increased absorption of heat radiation results that the matrix of
these plastics is intensely heat under the influence of locally
variable heat radiation in local areas, thus inducing undesirable
weak spots in these areas. Therefore, when using such materials in
areas which are exposed to an increased heat radiation, metallic
foils are applied which reflect the infrared radiation. Thus the
matrix temperature of these plastics in such protection areas can
be effectively lowered, i.e. the undesired material mutations such
as embrittlement, brittleness etc. can be avoided. This measure
allows the use of thermoplastic materials also in environments
which are exposed to high temperatures. Without such metallic
protective foils, components made of thermoplastic material undergo
a rapid aging process and are not usable in environments with
increased infrared radiation.
[0003] In particular, thermoplastic components are increasingly
utilized in modern automotive technology, as they are much lighter
in comparison to metallic components, can be user-defined and
inexpensively formed, and are easy to recycle. This leads to an
ever increasing significance of heat-protection for components used
in automotive technology. However, heat protection measures for
components in automotive technology have proven to be extremely
difficult to implement because of the extreme mechanical strains
placed on them such as vibration, wind forces, local temperature
fluctuations etc. Currently, such components are provided in a
known manner with a metallic foil at their thermally exposed areas
in order to protect them at these points from increased infrared
radiation. Unfortunately, this well-known measure leads to products
which only have a short-term life.
[0004] Thus, for example, U.S. Pat. No. 5,464,952 describes an
acoustically effective underfloor component for vehicles, having a
core layer made of a heat resistant and heat insulating fibrous
material. This core layer preferably comprises a non-woven material
made of glass fibers, ceramic fibers, basalt wool or mixtures
thereof and is provided on both sides with heat reflecting foils
made of aluminium or sheet metal in order to reflect any possible
infrared radiation which may impinge. The non-woven of this
underfloor component is provided at least at its peripheral regions
with a duroplastic bonding agent in order to attach the metallic
foils to the fibrous non-woven. At the same time this attachment
stiffens the peripheral region, which provides the entire
underfloor component with a certain form stability. The heat
reflecting foils preferably comprise a triple laminate foil having
a glass fiber layer, an aluminium layer and a thermoplastic
polyolefine layer, so that they may be loosely joined over their
entire surface in a form press to the non-woven which, as a rule,
is provided with a duroplastic bonding agent. This component also
has a relatively stiff peripheral region and a soft, i.e. pliable
central region.
[0005] In DE 197 05 511 A1 there is described a component utilized
as a heat shield comprising a carrier layer made of a thermoplastic
synthetic material and a heat protective layer made of aluminium.
Between the aluminium layer and the carrier layer there is provided
a thermoplastic connection layer (a hotmelt adhesive) made of
polypropylene (PP), polyester (PET), polyamide (PA) or
thermoplastic polyurethane (TPU), which melts during the forming
process and to which the aluminium layer is fixedly bonded at the
carrier layer. This aluminium layer is dimensioned to be much
larger than the area of maximum heat exposure (hot-spot region) and
is intended to dissipate the heat which impinges locally, i.e.
essentially convection heat. In order to improve the heat
conduction capacity, the aluminium layer utilized preferably has a
thickness of 0.08 to 0.2 mm and the surface of the heat shield can
be provided with particular deformations. In a preferred
embodiment, this heat shield comprises groove-like depressions
which run orthogonally to each other, and which are designed to
improve the stability and the cooling properties of the heat
shield. In order to effect this heat conducting function, this
metallic heat protection layer can be in the form of an expanded
metal.
[0006] Unfortunately it has been shown that these known foils which
are covered by a metallic foil and which are subjected to high
thermic stress are prone to rapid aging processes, i.e. they remain
intact for a short period only. In particular, delamination occurs
after a short while in such underfloor components, which makes the
use of such components in the automobile industry unsuitable. In
particular, the hotmelt adhesive between the metallic protective
foil and the carrier material loses its adhesive properties due to
the accelerated aging process caused by the high and constantly
changing temperature stress. Furthermore, the particularly
pronounced vibrations in this area of use provoke such components
to rapidly show signs of fatigue, breakage or local decomposition
and can lead to undesirable generation of noise.
[0007] From WO 99/44851 it is known to provide a fuel tank with an
integrated heat protection, and thereby to perforate the reflective
metallic foils in such a manner, that the perforation protrusions
thus produced are backflowed by thermoplastic synthetic material
during the manufacturing process, which leads to a positive
mechanically locking (clawing or bracketing) engagement and thus to
more durable products. Unfortunately, also with these components,
the plastics used in the perforation regions are only inadequately
protected against infrared radiation and thus can age more rapidly
in these areas.
[0008] It is therefore the aim of the present invention to provide
a heat-protected thermoplastic component which does not have the
mentioned disadvantages and which retains its adhesive properties
over its entire surface, even after prolonged use under thermic
radiation exposure. In particular, it is the aim of the present
invention to provide a heat-protected and vibration-resistant
vehicle underside component with a long life span.
[0009] This aim is solved according to the invention by a component
having the features of claim 1, and in particular by a component
having a carrier layer made of a thermoplastic synthetic, in
particular an LFT (endless fiber reinforced thermoplast) or a GMT
(glass fiber reinforced thermoplast), and a metallic foil connected
at least in part thereto, which comprises a multitude of small
folding pockets. These folding pockets are embedded in the
synthetic mass, i.e. they are mechanically anchored in the
synthetic mass and generate a long-term (i.e. more than 1000 hours
operating time at a temperature of about 140.degree. C.) constant
peeling resistance W.sub.s of, for example, at least 0.15
N/mm.sup.2 (W.sub.s>0.15 N/mm.sup.2). This anchorage or
bracketing of the metallic foil can be easily produced during the
forming process of said thermoplastic components, in that a knobbed
or similarly formed foil is inserted into a form nest or mold
together with the synthetic material to be formed. When the form
press is closed, the individual knobs, folds or similar pocket-like
elevations are partially compressed, turned-over or folded and form
more or less closed folding pockets. When the component is formed,
the thermoplastic synthetic can flow around the individual folding
pockets, and in this way produces a form-fitting or positive
connection with the metallic foil. The technology to form such
components by means of a forming process does not require any
specific technical knowledge by the expert and is not the subject
of the present invention. According to their specific use and
function requirements, the individual folding pockets can be
variously dimensioned, can be regularly or irregularly arranged,
can be coated with other materials, and can be totally or partially
circumflowed by plastic. In a preferred embodiment, at least 1 to 5
such folding pockets are arrayed in a sector of 10 to 30 mm. The
foil used is preferably made of aluminium and has a thickness of
0.01 to 0.1 mm, but can have a thickness of up to 0.5 mm.
[0010] In a further development of the present invention, a heat
resistant adhesive is provided between the foil and the synthetic
carrier, which does not lose its adhesive properties even under
increased thermic stress. It is self-evident that the expert may
provide further functional layers between the aluminium foil and
the thermoplast.
[0011] The component according to the invention is particularly
suitable for use in regions of motor vehicles which are subjected
to thermal stress, for example in the regions of the underside of
the engine compartment, the spare wheel compartment, the vehicle
tunnel, the dashboard cowl, the exhaust pipe or catalytic
converter, etc.
[0012] The advantages of the present invention are immediately
obvious to the expert and particularly are to be seen in that, with
these components, a closed foil completely protects the synthetic
from infrared radiation, thus preventing any delamination. The
peeling resistance, a gage for the adhesive properties and
vibration resistance, remains unchanged even after prolonged use,
i.e. at higher temperatures, and thus can also be used at regions
in vehicles which are subjected to particular exposure to heat.
Furthermore, the present invention makes a low-cost production of
the inventive components possible, in particular because the
shaping process of the thermoplastic material and the fixing or
attaching process of the metallic foil to this material can be
accomplished in one single method step. Furthermore, it is not
necessary to make any perforations, thus enabling a shorter
manufacturing time. Therefore, the components according to the
invention do not show any long-term signs of flaking or detachment,
even under increased vibration or heat stress and thus, when used
in vehicles, do not lead to an undesirable generation of noise.
[0013] In the following, the invention shall be more closely
described with the aid of an exemplary embodiment and with the aid
of the Figures. These show:
[0014] FIG. 1 a spacial view of a schematically illustrated
component according to the invention;
[0015] FIG. 2 an enlarged section through a schematically
illustrated component according to FIG. 1;
[0016] FIG. 3 a graphic illustration showing the long-term
performance of the peeling resisitance.
[0017] The component 1 shown in FIG. 1 comprises a trough-shaped
carrier layer 2 which is suitably formed according to its use. In
the view shown, a metallic foil 3 is inserted into this carrier
layer 2. According to the invention, this foil 3 comprises a
plurality of pocket folds 4 which mechanically couple the metallic
foil 3 to the carrier layer 2. The carrier layer is preferably made
of a glass fiber reinforced thermoplast (GMB) or a thermoplast
filled with endless fibers (LFT). Suitable materials are well known
to the expert. Products having endless fibers usually comprise
endless fibers in loops or slings, but can also simply be filled
with long fibers. The metallic foil is preferably made of aluminium
and has a thickness of 0.01 to 0.1 mm. However, it is understood
that this foil can be made of a different metallic material, and in
particular of a thin steel sheetmetal and have a thickness of up to
0.5 mm. Alternatively, a heat resistant adhesive layer (hotmelt
adhesive) can be provided between this metallic foil 3 and the
carrier layer 2, or additional heat insulating or acoustically
effective materials can be inserted. In a preferred embodiment, the
metallic foil 3 has 1 to 5 inventive folding pockets 4 spaced every
10 to 30 mm. These folding pockets 4 can be differently dimensioned
or arranged, according to their use requirements.
[0018] FIG. 2 shows a schematic view of a section through a
component 1 designed according to the invention. This has at least
on one side a metallic foil 3, which, in the finished component 1,
should act as a heat reflecting foil. Aluminium is preferably used
for this foil 3. This foil 3 is attached to a carrier layer 2 and
comprises folding pockets 4 which are embedded in the carrier layer
2. These folding pockets 4 result from the forming process and are
completely surrounded by the material of the carrier layer 2. The
shaping of these folding pockets 4 leads to a tight coupling, i.e.
a form-fitting or positive connection, between the metallic foil 3
and the carrier layer 2. These folding pockets are easily made by
using knobbed or otherwise shaped foils for the forming process.
According to the intended use, these folding pockets 4 can be
differently dimensioned and/or arrayed by the expert. For the
present invention it has proven to be particularly beneficial that,
for this type of anchorage, the foil 3 does not have to be provided
with perforations in order to be able to achieve a positive
connection. In particular, the anchorage regions 6, i.e. the
regions having the folding pockets 4, are protected against the
infrared radiation which damages the thermoplastic material of the
carrier layer 2. For other purposes, e.g. acoustic purposes, the
expert can, of course, provide the foil 3 with perforations and to
use a different material for the carrier layer 2, or to provide a
further intermediate layer between the metallic foil 3 and the
carrier layer 2. It is thus at the discretion of the expert to
include an intermediate layer, for example a hotmelt adhesive, a
ceramic layer and/or an acoustically effective layer.
[0019] During the shaping process, a metallic foil 3, which has
previously been knobbed or has otherwise been provided with
geometric deformations, is arranged in a heated form press and is
covered with an LFT, GMT or other suitable synthetic material.
Thereby the side having the deformations, especially the knobs,
faces the synthetic material and these deformations are compressed,
crushed or randomly folded when the synthetic material is applied.
This leads to the formation of the pocket folds according to the
invention, which permit the flowable plastics material to flow
behind the individual pocket folds 4 so as to completely engulf
them. It is thus possible to achieve a positive connection in a
simple manner. The fibrous plastics material is hardened during the
shaping process so as to form the desired carrier layer 2. At the
same time, the curing of the plastics layer 2 results in a secure
and long-term stable mechanical connection with the metallic foil
3.
[0020] FIG. 3 is a graphical illustration of the measurement
results to the peeling resistance W.sub.s with different
arrangements A, B, C. Here, W.sub.s is understood to mean the
ability of the metallic foil to bond to the thermoplastic carrier
part, i.e. a gage for the required energy per surface unit to
separate the metallic foil 3 from the carrier layer 2. The values
in area (I) pertain to arrangements which have not been subjected
to an aging process, whilst the values in area (II) pertain to
arrangements which have been subjected to temperatures of
140.degree. C. during a period of 1000 hours. The values A(I) and
A(II) relate to an arrangement A, for which a conventional metallic
hotmelt adhesive (MSK25) was used between an LFT-component and an
aluminium foil. The measurement results show that no measurable
adhesion was obtained.
[0021] The values B(I) and B(II) relate to an arrangement B, for
which an adhesive being optimized for the bonding of aluminium and
polypropylene (HSK15) was used between an LFT-component and an
aluminium foil. The measurement values B(I) obtained thereby make
it clear that with this arrangement in a non-aged condition, an
extremely high peeling resistance W.sub.s=1.2 N/mm.sup.2 can be
achieved. However, the measurement values B(II) show that the
peeling resistance after the aging process W.sub.s=0.15 N/mm.sup.2
is reduced (about 85% reduction of the adhesive value).
[0022] The values C(I) and C(II) relate to an arrangement C
according to the invention, in which an aluminium foil provided
with form pockets is applied to an LFT-component, and between this
LFT-component and the aluminium foil no adhesive was used. The
peeling resistance resulting from the inventive arrangement C and
without the use of an additional adhesive, in a non-aged condition,
results in a value of W.sub.s=0.2 N/mm.sup.2, whilst the peeling
resistance for this arrangement C, and after 1000 hours heat
treatment, has only decreased to W.sub.s=0.16 N/mm.sup.2 (about 20%
reduction of the adhesive capacity). These measurement results make
evident the efficiency of the present invention. In particular, and
without a further inventive step, the expert may suitably adjust
and optimize the dimensions and shape of the folding pockets.
* * * * *