U.S. patent application number 11/502311 was filed with the patent office on 2006-12-07 for composite extrusion for trim seal strip and method for forming same.
This patent application is currently assigned to GenCorp Inc.. Invention is credited to Krishnamachari Gopalan.
Application Number | 20060272217 11/502311 |
Document ID | / |
Family ID | 34521560 |
Filed Date | 2006-12-07 |
United States Patent
Application |
20060272217 |
Kind Code |
A1 |
Gopalan; Krishnamachari |
December 7, 2006 |
Composite extrusion for trim seal strip and method for forming
same
Abstract
A composite extrusion for an automotive seal strip is formed of
an extruded body, and a veneer extruded onto the body. The extruded
body is composed of ethylene-propylene diene rubber compound. The
veneer is composed of a polymer blend that includes the reaction
product of an acrylate polymer and a glycidyl acrylate polymer. The
reaction of the acrylate polymer and the glycidyl acrylate polymer
improves adhesion and also provides a barrier to inhibit migration
of vulcanizing agents from the ethylene-propylene diene rubber body
into the veneer that would otherwise cause discoloration during
use.
Inventors: |
Gopalan; Krishnamachari;
(Troy, MI) |
Correspondence
Address: |
BRINKS HOFER GILSON & LIONE
P.O. BOX 10395
CHICAGO
IL
60610
US
|
Assignee: |
GenCorp Inc.
|
Family ID: |
34521560 |
Appl. No.: |
11/502311 |
Filed: |
August 10, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10690141 |
Oct 21, 2003 |
|
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11502311 |
Aug 10, 2006 |
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Current U.S.
Class: |
49/490.1 |
Current CPC
Class: |
B29C 48/304 20190201;
B60J 10/24 20160201; B32B 27/18 20130101; B29C 48/12 20190201; B29C
48/022 20190201; B32B 25/08 20130101; B32B 2323/16 20130101; B29K
2023/16 20130101; B60R 13/0206 20130101; Y10T 428/31935 20150401;
B29K 2301/10 20130101; B32B 37/153 20130101; B32B 2038/0076
20130101; B32B 2581/00 20130101; Y10T 428/31938 20150401; B60J
10/32 20160201; B60J 10/265 20160201; Y10T 428/31931 20150401; B29C
48/07 20190201; Y10T 428/24198 20150115 |
Class at
Publication: |
049/490.1 |
International
Class: |
E06B 7/16 20060101
E06B007/16 |
Claims
1. A method for forming a composite extrusion for a trim seal strip
comprising: extruding a body composed of ethylene-propylene diene
rubber compound and having a surface; extruding a layer onto said
surface and composed of a polymer blend comprising an acrylate
polymer and a glycidyl acrylate polymer; and curing said layer to
form a veneer bonded to the body, wherein said curing includes
reacting said acrylate polymer and said glycidal acrylate
polymer.
2. The method of claim 1 wherein said surface comprises diene
groups and wherein said curing includes reacting a portion of said
glycidyl acrylate polymer and said diene groups.
3. The method of claim 1 wherein the coating contains a coloring
agent.
4. The method of claim 1 wherein the acrylate polymer and the
glycidyl acrylate polymer form a reaction product having an
affinity for ethylene-propylene diene rubber compound and forming
an interfaced barrier effective to inhibit migration of polar
agents from said body into said veneer.
5. The method of claim 1 wherein the glycidyl acrylate polymer is
an ethylene glycidyl acrylate polymer.
6. The method of claim 1 wherein the glycidyl acrylate polymer is
ethylene methyl acrylate glycidyl methacrylate terpolymer.
7. A method for forming a composite extrusion comprising: extruding
a body composed of a ethylene-propylene diene precursor that
includes diene groups and a vulcanizing agent; extruding onto said
body a veneer composed predominantly of a polyolefin compound and
comprising a acrylate-based polymer and an ethylene glycidyl
acrylate polymer; and curing said body and said veneer to vulcanize
the ethylene-propylene diene precursor to form ethylene-propylene
diene rubber compound, and concurrently to react said
acrylate-based polymer and said ethylene glycidyl acrylate compound
in said veneer.
8. The method of claim 7 wherein a portion of said ethylene
glycidyl acrylate polymer reacts with diene groups at a surface of
said body to enhance adhesion of the veneer to the body.
9. The method of claim 7 wherein the reaction between said
acrylate-based polymer and said ethylene glycidyl acrylate polymer
forms a reaction product that provides a compatabilized polar
interfacial barrier adjacent said ethylene-propylene diene rubber
compound effective to inhibit migration of residual vulcanizing
agents into the veneer.
10. The method of claim 7 wherein the glycidyl acrylate polymer is
ethylene methyl acrylate glycidyl methacrylate terpolymer.
11. The method of claim 7 wherein the veneer comprises a coloring
agent.
12. The method of claim 7 wherein the veneer is composed
predominantly of a thermoplastic polyolefin.
13. The method of claim 12 wherein the thermoplastic polyolefin is
a polyolefin elastomer.
14. A composite extrusion for a trim seal comprising: a body
composed of ethylene-propylene diene rubber compound; and a veneer
extruded onto the body and composed of a polymer blend that
includes a reaction product of an acrylate polymer and a glycidyl
acrylate polymer.
15. The composite extrusion of claim 14 wherein the veneer is
composed predominantly of a polyolefin compound, and wherein the
reaction product is a compatibilizer to enhance adhesion of the
veneer to the base.
16. The composite extrusion of claim 14 wherein the veneer contains
a coloring agent.
17. The composite extrusion of claim 14 wherein the glycidyl
acrylate polymer is an ethylene glycidyl acrylate polymer.
18. The composite extrusion of claim 14 wherein the glycidyl
acrylate polymer is ethylene methyl acrylate glycidyl methacrylate
terpolymer.
19. A composite extrusion adapted for an automotive trim seal, said
composite extrusion comprising: a body composed of
ethylene-propylene diene rubber compound; and a co-extruded veneer
applied to the body and composed of a blend comprising
predominantly polyolefinic compound and containing a reaction
product of an acrylate polymer and an ethylene glycidyl acrylate
polymer.
20. The composite extrusion of claim 19 wherein the composite
extrusion comprises an interface between the body and the veneer,
and wherein the interface comprises a reaction product of a diene
group of said ethylene-propylene diene rubber compound and said
glycidyl acrylate polymer.
21. The composite extrusion of claim 19 wherein the veneer contains
a coloring agent.
22. The composite extrusion of claim 19 wherein the
ethylene-propylene diene rubber compound contains a residual
vulcanizing agent, and wherein said reaction product provides a
barrier effective to inhibit migration of the residual vulcanizing
agent into the veneer.
23. The composite extrusion of claim 19 wherein the ethylene
glycidyl acrylate polymer is ethylene methyl acrylate glycidyl
methacrylate terpolymer.
24. The composite extrusion of claim 19 wherein the polyoelfin
compound is a polyolefin elastomer.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] This invention relates to a trim seal strip formed of a
composite extrusion. More particularly, this invention relates to
such trim strip that comprises an extruded base composed of
ethylene-propylene diene rubber compound and a co-extruded veneer
composed of a polymer blend that includes a reaction product of an
acrylate polymer and a glycidyl acrylate polymer.
BACKGROUND OF THE INVENTION
[0002] It is common practice in automotive vehicles and elsewhere
to use a trim seal strip about a door or window. For example, in
automotive vehicles, a primary door trim seal strip is attached to
a body panel about an opening for a door and seals against the door
when closed. The trim seal strip is formed of an extruded polymeric
material. A preferred material is composed of ethylene-propylene
diene rubber compound, commonly referred to as a EPDM. The trim
strip is formed by extruding an unvulcanized blend that contains an
EPDM compound with fillers, plasticizers and a vulcanizing agent,
and curing the extrusion to crosslink the polymer and form the
product rubber compound. The material includes carbon black filler
that provides a dark black appearance and reinforcement. On visible
surfaces of the trim strip, it is desired to apply a coating having
a non-black color that coordinates with surrounding colors to
provide an aesthetically pleasing appearance. For example, for an
automotive primary door trim strip, an interior surface may be
coated to coordinate with a color of a headliner in the vehicle. A
suitable coating has been formed of colored EPDM rubber, or colored
thermoplastic material. Such coatings are relatively soft and
susceptible to scratching and marring. EPDM veneers are difficult
to color match. On the other hand, thermoplastic layers tend to
have poor adhesion to the EPDM base. Still further, during use,
residual zinc sulfur agents from the vulcanizing process tend to
leach from the EPDM base into the thermoplastic layer and cause
discoloration.
[0003] Therefore, a need exists for a trim strip for automotive
applications and the like that is formed of an extruded EPDM base
and includes a veneer having an aesthetically pleasing color and
formed of a material having enhanced mar resistance and improved
adhesion, and further providing a barrier to inhibit migration of
residual agents from the base that would otherwise result in
staining of the veneer.
SUMMARY OF THE INVENTION
[0004] In accordance with this invention, a composite extrusion
comprises a body composed of ethylene-propylene diene rubber
compound. A veneer is extruded onto the body and is composed of a
polymer blend that includes an acrylate polymer and a glycidyl
acrylate polymer, preferably an ethylene glycidyl acrylate polymer.
Upon curing, the glycidyl acrylate polymer reacts with the acrylate
polymer and serves as a compatibilizer to enhance adhesion of the
veneer to the base. Also, it is believed that the reaction product
forms an interfacial barrier to inhibit migration of stain-inducing
residual agents from the base into the veneer. As a result, the
veneer may be readily formulated with a coloring agent to provide a
durable trim that is aesthetically pleasing and well suited for use
in automotive and like applications.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] This invention will be further described with reference to
the accompanying drawings wherein:
[0006] FIG. 1 is a cross-section of an extruded trim in accordance
with a preferred embodiment of this invention.
DETAILED DESCRIPTION OF THE INVENTION
[0007] In accordance with a preferred embodiment, referring to the
Fig., a primary door trim seal strip 10 is adapted to fit about a
door opening of an automotive vehicle to form a seal against a
door. It will be appreciated that strip 10 depicted in FIG. 1 is a
conventional scorpio-type design and is by way of example only. The
particular design of the trim seal strip depends upon the nature of
the application, the design of the vehicle, and other factors. It
is an advantage that this invention may be readily adapted for
forming seals of other designs and for other applications,
including glass seals.
[0008] Strip 10 comprises an extruded main body 12 that is adapted
for installation in a body panel about the door opening, and a
flexible sealing ring 14 co-extruded with body 12 and adapted to
engage the vehicle door for forming a seal thereagainst. Body 12
may include a metallic or polymeric carrier (not shown). During
manufacture, main body 12 is extruded about the carrier and cured,
whereupon the carrier becomes embedded therein. Body 12 also
includes a flange 16 that overlies a border of a headliner when
installed in a vehicle to cover a seam between the headliner and
the body panel. In accordance with this invention, visible surfaces
of main body 12 are covered by a co-extruded veneer 18. Veneer 18
preferably contains coloring agents to coordinate with the adjacent
headliner and provide an aesthetic appearance.
[0009] Main body 12 is formed by extrusion and is composed of a
dense ethylene-propylene diene rubber compound, referred to as
EPDM. EPDM is a thermoset material that is characterized by a
polymeric backbone derived from ethylene and propylene monomers and
includes a side chain formed of a diene termonomer. A preferred
diene termonomer is ethylidene norbornene. Alternately,
dicyclopentadiene is a suitable termonomer. The diene precursor is
formulated with a sulfur-containing vulcanizing agent, which is
commonly an organic zinc sulfur complex. The formulation also
preferably includes antioxidants and ultraviolet light absorbers,
as well as a carbon black filler that reinforces the product and
imparts a black coloration. Thereafter, during curing, the
sulfur-containing agent reacts with the diene groups to cross-link
the polymer and form the product thermoset material. Sealing ring
14 is composed of a sponge EPDM compound similar to the dense
material of boy 12 but including a foaming agent that enhances
flexibility of the product compound.
[0010] In accordance with this invention, veneer 18 is formed of a
polymeric blend that contains an acrylate polymer and an ethylene
glycidyl polymer. Preferably, the blend is composed predominantly
of polyolefin elastomer (m-POE), high density polyethylene (HDPE)
thermoplastic polyolefin rubber (TPO) or other suitable
polyolefinic compound. By way of a preferred example, a suitable
blend was obtained containing about 70 weight percent m-POE, 20
weight percent of acrylate polymer and 10 weight percent ethylene
glycidyl polymer. The m-POE is commercially available from DuPont
Dow Elastomers under the trade designation Engage 8100. The
acrylate polymer is an acrylate-based terpolymer commercially
available from Goodyear Chemicals Europe under the trade
designation Sunigum P7395. The preferred ethylene glycidyl acrylate
is ethylene methyl acrylate glycidyl methacrylate, commercially
available from Elf-Atochem under the trade designation Lotader
AX8900 and is referred to as EMA-GMA. The blend was obtained as
pellets, melted and extruded as a layer onto the surface of a cured
EPDM body at a temperature of about 300.degree. F. The main body
was formed by extruding and curing EPDM precursor having diene
groups derived from ethylidene norbornene termonomer. The composite
was heated at a temperature between about 400.degree. F. and
500.degree. F. to react the an acrylate components to form the
product veneer. In comparison to veneers applied to EPDM bodies and
formed of polyolefin compounds without the acrylate additive, the
veneer in accordance with this invention exhibited improved
adhesion and enhanced mar resistance. In addition, the veneer
exhibited improved weatherability, and, in particular, reduced
discoloration in the presence of the EPDM material.
[0011] In the aforementioned example, the veneer compound was
applied to an EPDM-base body that was vulcanized. In commercial
production, the veneer compound may be co-extruded onto the EPDM
base prior to curing, and the two materials concurrently cured by
heating to a temperature between about 450.degree. F. and
650.degree. F., preferably about 500.degree. F. Also, additives are
preferably added to the blend to enhance the properties of the
product veneer. In particular, it is desired to add coloring agent,
typically in an amount between about 0.05 and 3 weight percent, to
produce a desired color for the veneer. Also, materials adapted for
commercial use preferably include, antioxidants and ultraviolet
light absorbers, and optionally may contain plasticizers in an
amount up to about 20 weight percent.
[0012] While not limited to any particular theory, it is believed
that the reaction of the acrylate-based polymer and the ethylene
glycidyl acrylate polymer in the veneer produces a product that
exhibits an affinity for the EPDM base to form an interfacial
compatabilized polar barrier film. Formation of the polar barrier
film may be enhanced as a result of reaction between unreacted
surface diene groups of the EPDM base and ethylene glycidyl
acrylate polymer in the veneer compound, particularly when the
veneer blend is applied to pre-vulcanized EPDM material, and the
materials are concurrently cured. It is pointed out that the EPDM
is commonly formulated to contain organic zinc sulfur complexes in
excess of stociometric quantities required for curing. For
polyolefin veneers applied to EPDM base without the acrylate
additives in accordance with this invention, the zinc sulfur
complexes tend to migrate from the EPDM base into the polyolefin
layer and, for layers containing a coloring agent, tend to produce
localized discoloration. In contrast, the affinity of the polar
zinc sulfur complex for the polar reaction product between the
acrylate-based polymer and the ethylene glycidyl acrylate compound
in accordance with this invention inhibits further migration of the
complex to the surface and thus inhibits discoloration at the
surface that would otherwise be readily visible during weathering
tests. Thus, the addition of the ethylene glycidyl acrylate polymer
serves both as a compatilizer to promote adhesion of the
acrylate-containing polyolefin blend to the EPDM surface and also
promotes weathering resistance. Moreover, the addition of the
acrylate polymer promotes hardness within the polyolefin layer and
results with improved mar resistance.
[0013] While this invention has been described in terms of certain
embodiments thereof, it is not intended to be so limited, but
rather only to the extent set forth in the claims that follow.
* * * * *