Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1339~07
CORROSION PROTECTION ELEMENT FOR PARTS, PARTICULARLY
AUTOMOTIVE PARTS, TO BE CONNECTED BY SCREWS, BOLTS, ETC.
The invention relates to a corrosion protection
element for parts, particularly automotive parts, to be
connected by screws, bolts and the like and consisting at
least in part of metal, said corrosion protective element
being adapted to be provided between said parts at the
juncture thereof and including zinc in layer form.
It is necessary frequently to provide for
protection against corrosion between constructional
components that are to be connected to each other -- such
as, in the automotive industry, components that are to be
attached to the chassis or to the body of a vehicle.
For obtaining optimum protection from corrosion,
it has been known to provide a coat of zinc on the entire
body of a vehicle. On all of the vehicle body surface,
this coat of zinc will act as a cathode whenever corrosive
processes take place. The provision of a coat of zinc on
the entire surface of a vehicle body is most costly,
however. In addition, problems arise when internally
threaded bores must be provided on the body for attaching
components; such internally threaded bores will disrupt
the zinc coating. Even if such bores are provided on the
body before the zinc coating is applied, movements of the
attached components relative to the body at the threaded
bores will again disrupt the zinc coating, giving rise to
corrosive damage within a short period of time.
It has been known furthermore to use a self-
0 adhesive zinc foil as an element affording protection from
corrosion, such foil being provided at the juncture of
rubber components and steel components or between other
metal attachments, for exa~ple; see Japanese Patent
61,179,886. A zinc foil of this kind does not provide for
a seal at the juncture of the parts to be connected and is
damaged rather easily by mechanical movements of the parts
between which it is located. As has been known, a
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satisfactory protection of connected parts from corrosion
will be obtained by the application of several layers of -
paint; this again does not result in a seal between the
parts to be connected. Besides, the coats of paint will
be damaged by mechanical movements of the parts connected.
Optimum protection from corrosion is obtainable
where the parts to-be connected are high-grade steel, such
as chrome-nickel steel. A suitable seal at the juncture
between the parts to be connected may be obtained by any
sealing compound or sealing tape which will accommodate
slight mechnical movements. This kind of protection from
corrosion is very expensive, however.
Finally, there has been known a great number of
sealing compounds which are not impaired by relative
movements of the parts to be connected. Compounds of this
kind do not afford any protection from corrosion, however.
It is the object underlying the invention to
provide in a cost-effective manner a corrosion protection
element of the type specified above which provides an
excellent seal at the juncture of the parts to be joined,
as well as optimum protection from corrosion, regardless
of relative movements of the parts connected to each
other.
In accordance with the invention, this object is
achieved by a laminate comprising two high-purity zinc
foils providing cathodic anticorrosive action, said foils
being disposed in a mutually overlying relationship and
having therebetween a layer of an elastic sealing
material, said laminate conforming in an optimum manner to
and sealing the gap between the parts to be connected as
these parts are being connected with each other.
Preferred embodiments of the invention are
defined by dependent claims 2 to 12.
It is preferred that the zinc foils be adhered to
the layer of sealing material by means of adhesive layers.
The laminate may have any desired geometric shape
in plan view. It is preferred that the laminate be
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manufactured in a continuous or strand form. The
elastomer may be a paste composition on the basis of
polyisobutylene, (butyl) or polyurethane, for instance, or
may be present in the form of a closed-cell foam adhesive
tape. The closed-cell form adhesive tape may be acrylic
foam or a neoprene or polyether tape, for example. In the
joining of the aforesaid parts such as the fixing of an
attachment by means of screws, it is important that the
elastic adhesive sealing material exhibit excellent
conformability and strong adhesion for the desired sealing
effect; in addition, it should be a closed-cell material.
For use of the inventive corrosion protective
element in the automotive industry, it is of major
importance that the laminate accept automotive body
paints.
In a one-year long-term test of a test vehicle
under corrosion promoting conditions corresponding to a
vehicle life of about ten years in a normal environment,
the inventive corrosion protection element was found not
to be damaged or wear, and no corrosion was found in the
areas where attachments were connected. As a result, the
inventive corrosion protection element provides excellent
protection from corrosion as well as an excellent seal
particularly between screwed-on attachments and the
substrate, such as fenders and the automobile body to
which they are attached. The permanently elastic adhesive
layer of the laminate provides for easy application of the
inventive corrosion protection element in the vicinity of
the bores provided in the attachments. As the screws are
tightened, the laminate will in an optimum manner conform
to and seal the gap between the parts to be joined,
permanently sealing that gap. The zinc provides for
cathodic anticorrosive action in the gap and on the bore
walls. As the entire laminate is permanently elastic, it
exhibits long life and stability against aging despite
relative movements between the joined parts. Because of
its advantages in the assembly process and the permanent
13394~7
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anticorrosive effect, the inventive corrosion protection
element is most cost-effective. The adhesive-protecting .
liner protects the permanently elastic self-adhesive layer
from soiling before the laminate is put to use. The
inventive corrosion protection element has major
advantages particularly in the automotive, naval, and
aircraft industries- and for stationary installations which
require permanent stability in a humid environment.
The inventive corrosion protection element will
now be explained in greater detail under reference to the
drawings.
Fig. 1 shows a schematic perspective view of the
corrosion protection element;
Fig. 2 schematically shows the use of a corrosion
protection element for fastening a fender to a
wheel case by means of threaded bolts;
Fig 3 shows another embodiment of the invention, used
to protect the fastening bolts of a bicycle
stand.
As shown in Fig. 1, the corrosion protection
element comprises a laminate 1 which may be manufactured
in a continuous form and has two spaced high-purity zinc
foils 2 having therebetween a layer 3 of an elastic
adhesive sealing material engaging the facing sides of
foils 2. A layer 4 of a permanently elastic adhesive is
provided on the opposite side of lower zinc foil 2 (Fig.
1). In the storage condition of the corrosion protection
element, that layer 4 is covered by an adhesive-protecting
liner 5 which may be stripped away readily before use.
Fig. 2 shows the use of the corrosion protection
element for fastening a fender 6 to the wheel case of a
vehicle body 7. After bores 9 have been provided in the
vehicle body and in fender 6 to be attached, adhesive-
protecting line 5 is stripped from laminate 1, and the
latter is applied with the self-adhesive surface of layer
4 of permanently elastic adhesive down on vehicle body 7
above bores 9 (in Fig. 2). Thereafter, fender 6 is fitted
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to the wheel case in vehicle body 7 and to the corrosion
protection element placed thereon, and threaded bolts 10 .
are introduced in bores 9 and tightened to secure the
fender to the wheelcase. As bolts 10 are tightened,
laminate 1 of the corrosion protection element conforms in
an optimum manner to and permanently seals the juncture 11
between fender 6 and wheel case 7. High-purity zinc foils
2 of lamnate 1 provide cathodic anticorrosive action in
area 11 and in bores 9. secause of the permanent
elasticity of the corrosion protection element, that
element itself and the connection between the joined
vehicle parts show a long life and a high stability
against aging despite relative movements of fender 6 and
the wheel case of vehicle body 7 during vehicle operation.
In particular, the self-adhesive coating of laminate 1 and
the deformability of layer 3 of an elastic adhesive
sealing material provide for easy assembly of the
corrosion protection element and for easy installation of
fender 6 on wheel case 7 of the vehicle body.
Fig 3 shows another example of the use of the
inventive element on a roofed bicycle stand, which
comprises supporting structure of steel beams 13 which is
maintained in the assembled condition by means of threaded
bolt-and-nut fastener combinations 14 provided adjacent
sheet-metal roof sections 15. For protection from
corrosion, the inventive laminate 1 is provided above and
below fastener combinations 14 to seal joint 16. In
conventional assemblies of this kind, corrosion will be
caused by the slight but unavoidable relative movements of
the connected parts that are caused by wind and other
mechanical forces acting on the stand.
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Example
A multi-layer construction consisting of the following
materials including dimensional data:
s
Material Description Dimensions
Zinc Foil Matt Silver .075 mm thickness
99.5 purity
10 Sealant Grey paste of 1.645 mm thickness
Polybuten type
Zinc Foil Matt Silver .075 mm thickness
99.5 purity
Adhesive Modified acrylate .12S mm thickness
15 Liner Siliconized .080 mm thickness
protection paper
Total thickness 2.000 mm
Width 8.000 mm
Total length 1.0 m
Initial adhesion
(AFER A-steel,
180~ peel
300 mm/min) > 20 N/25 mm
Weight/area 2
(without liner) 0.50 +/- 0.05 grs/cm
