U.S. patent application number 10/914832 was filed with the patent office on 2005-02-17 for automobile assembly.
Invention is credited to Cate, Peter J., Koelman, Hein J., Naughton, Padraig.
Application Number | 20050035609 10/914832 |
Document ID | / |
Family ID | 9916712 |
Filed Date | 2005-02-17 |
United States Patent
Application |
20050035609 |
Kind Code |
A1 |
Cate, Peter J. ; et
al. |
February 17, 2005 |
Automobile assembly
Abstract
A method is provided for making an automobile assembly having a
moulded plastics structural member and a reinforcing member in
which a polymerisable adhesive is employed to bond the two members
together and an automobile assembly having a bonded structural
member and a reinforcing member. The assembly is suitably used as a
"front end carrier" or a bumper system in an automobile.
Inventors: |
Cate, Peter J.; (Blockley,
GB) ; Naughton, Padraig; (Ringstrasse, DE) ;
Koelman, Hein J.; (Zum Kohlwaldfeld, DE) |
Correspondence
Address: |
THE DOW CHEMICAL COMPANY
INTELLECTUAL PROPERTY SECTION
P. O. BOX 1967
MIDLAND
MI
48641-1967
US
|
Family ID: |
9916712 |
Appl. No.: |
10/914832 |
Filed: |
August 10, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10914832 |
Aug 10, 2004 |
|
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10171936 |
Jun 14, 2002 |
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Current U.S.
Class: |
293/120 |
Current CPC
Class: |
B62D 25/084 20130101;
B62D 21/152 20130101; B62D 29/005 20130101; B62D 29/001
20130101 |
Class at
Publication: |
293/120 |
International
Class: |
B60R 019/03 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 15, 2001 |
GB |
0114684.4 |
Claims
1. A method for producing an automobile assembly comprising a
structural member made of a moulded plastics material having a low
energy surface and a reinforcing member attached to the structural
member, the members having complementary surfaces, which comprises
applying an adhesive to the complementary surface of the structural
member and/or reinforcing member, bringing the complementary
surfaces of the reinforcing member and structural member into
contact and allowing the adhesive to set so as to bond the
structural member and reinforcing member together wherein the
adhesive is capable of bonding to a low energy surface plastic.
2. A method according to claim 1 in which the low energy surface
plastics material has a surface energy of less than 45
mJ/m.sup.2.
3. A method according to claim 1 in which the plastics material
comprises a homopolymer selected from a polyolefin, a polystyrene
and a polyamide or a copolymer.
4. A method according to claim 1 in which the plastics material
comprises fibre.
5. A method according to claim 4 in which the fibre is selected
from short glass fibre, long glass fibre, short natural fibre or
long natural fibre.
6. A method according to claim 1 in which the plastics material is
selected from short glass fibre filled polypropylene, long glass
fibre filled polypropylene, glass filled polyamide and glass filled
polyamide alloys.
7. A method according to claim 1 in which the reinforcement is made
of steel and/or aluminium.
8. A method according to claim 1 which comprises applying the
adhesive directly to the surface of the structural member without
treatment or priming of the said surface.
9. A method according to claim 1 in which the structural member and
reinforcing member are bonded together by a continuum of adhesive
along the complementary surfaces on the two members.
10. A method according to claim 1 in which the reinforcing member
comprises contours or channels which are complementary with the
surface of the structural member so as to provide resistance to
stress by means of adhesion and/or abutment between the structural
and reinforcing member.
11. A method according to claim 1 in which the adhesive comprises a
polymerisable composition.
12. A method for producing an automobile assembly comprising a
structural member made of a moulded plastics material having a low
energy surface and a reinforcing member attached to the structural
member, the members having complementary surfaces, which comprises
providing an adhesive comprising a polymerisable composition,
contacting together the components of the composition under
conditions to initiate polymerisation, applying the adhesive to the
complementary surface of the structural and/or reinforcing member,
bringing the complementary surfaces of the reinforcing member and
structural member into contact and curing the adhesive whereby the
said members bond together.
13. A method according to claim 11 or claim 12 in which the
polymerisable composition comprises an organoborane/amine complex
and one or more of monomers, oligomers or polymers having olefinic
unsaturation which is capable of polymerisation by free radical
polymerisation.
14. A method according to claim 13 in which the polymerisable
composition further comprises a compound which causes the said
complex to disassociate so as to release the organoborane to
initiate polymerisation of one or more of monomers, oligomers or
polymers having olefinic unsaturation.
15. A method according to claim 13 in which the amine part of the
organoborane/amine complex is selected from the group of amines
having an amidine structural component; aliphatic heterocycles
having at least one nitrogen in the heterocyclic ring; primary
amines which in addition have one or more hydrogen bond accepting
groups wherein there are at least two carbon atoms between the
primary amine and the hydrogen bond accepting group; and conjugated
imines.
16. A method according to claim 15 in which the amine is selected
from dimethylaminopropyl amine, methoxypropyl amine,
dimethylaminoethylamine, dimethylaminobutylamine, methoxybutyl
amine, methoxyethyl amine, ethoxypropylamine, propoxypropylamine,
amine terminated polyalkylene ethers (such as trimethylolpropane
tris(poly(propyleneglycol), amine terminated)ether),
aminopropylmorpholine, isophoronediamine, and
aminopropylpropanediamine.
17. A method according to claim 13 in which the organoborane part
of the organoborane/amine complex is selected from a trialkyl
borane and an alkyl cycloalkyl borane.
18. A method according to claim 17 in which the organoborane is
selected from tri-ethyl borane, tri-isopropyl borane and
tri-n-butylborane.
19. A method according to claim 13 in which the molar ratio of
amine compound to organoborane compound is from 1.0:1.0 to
3.0:1.0
20. An automobile assembly comprising a structural member made of a
moulded plastics material having a low energy surface and a
reinforcing member attached to the structural member, the
structural member and reinforcing member having complementary
surfaces and being attached by means of an adhesive, which is
capable of bonding to a low energy surface substrate, on at least
part of at least one of the complementary surfaces.
21. An automobile assembly comprising a structural member made of a
moulded glass filled polypropylene and/or glass filled polyamide
having a surface energy of less than 45 mJ/m.sup.2, and a
reinforcing member made from a metal selected from steel, zinc and
aluminium attached to the structural member, the structural member
and reinforcing member having complementary surfaces and being
attached by means of an adhesive which is capable of bonding to a
substrate having a surface energy of less than 45 mJ/m.sup.2
disposed between at least part of the complementary surfaces so as
to bond them together, the adhesive being derived from a
polymerisable composition comprising i) a complex between an
organoborane and an amine; ii) one or more of monomers, oligomers
or polymers having olefinic unsaturation which is capable of
polymerisation by free radical polymerisation; and, optionally iii)
a compound which causes the complex to disassociate so as to
release the organoborane to initiate polymerisation of said one or
more of monomers, oligomers or polymers having olefinic
unsaturation.
22. An automobile assembly according to any one of claims 20 and 21
for an automobile which has two sides wherein the assembly
comprises a front end carrier and the carrier joins the two sides
of the automobile together at the front of the automobile and in
which the assembly is aligned transversely so as to define a
compartment.
23. An automobile assembly according to any one of claims 20 and 21
wherein the assembly comprises a bumper system in which: i) the
reinforcing member is an energy absorbing unit made of metal or
plastics material and the structural member is a bumper fascia made
of plastics material; or ii) the reinforcing member is a bumper
beam made of metal and the structural member is an energy absorbing
unit made of plastics material.
24. An assembly according to claim 23 in which the energy absorbing
unit defined in part i) or part ii) of claim 23 has a generally "C"
shaped cross section.
Description
BACKGROUND TO THE INVENTION
[0001] This invention relates to an automobile assembly, in
particular to structural assemblies employed at the front end known
as a "front end carrier" or rear end of an automobile and also to
assemblies for use as bumper systems. The invention is especially
concerned with automobile structural assemblies having a
reinforcing member and a structural member which are connected
together by means of an adhesive.
[0002] An automobile bumper system typically comprises a "bumper
beam" and a "bumper fascia". Typically the bumper beam is bolted to
the chassis of the automobile and the fascia is connected to the
body panels. An energy absorption unit is typically disposed
between the fascia and beam. A bumper beam is typically made of a
rigid material, for example steel and aluminium, to provide
structural integrity and an impact reaction surface and may act as
a reinforcing member in the bumper system. The "bumper fascia" is
shaped so as to abut or to be connectable to the energy absorption
unit and also to have aesthetic appeal, it being part of the
external part of the bumper system. A "bumper fascia" may typically
be made of or comprise a moulded plastics material.
[0003] Energy absorption units (EAU) may be made of metal, for
example steel and aluminium, or may be made of plastics material.
The EAU compresses or distorts on impact so absorbing the energy of
the impact. Conventional plastic bumper EAUs may be assembled for
example by heating staking points so as to weld the plastics
material of the EAU and the fascia together. This process may
however leave undesirable visible marks on the fascia.
[0004] The fascia may also be attached to the EAU using mechanical
fixing means.
[0005] The EAU may be connected to the bumper beam or may be
located close to but spaced from the beam. Typically, the EAU may
be connected to the beam using mechanical fixing means.
[0006] Referring to FIG. 12, a "front end carrier" (21) (hereafter
FEC) for an automobile (22) is that part of the body of the
automobile which joins the two sides (23 and 24) of the front of
the automobile (22) together and is aligned transversely so as to
enclose a front, typically engine, compartment (25). The FEC is
shaped for aesthetic and functional purposes, and typically houses
or is otherwise used to carry one or more of the lighting
assemblies, the cooling system and the latch by which the bonnet is
secured when closed.
[0007] Traditional adhesives do not bond effectively to plastics
materials of the type used in FECs and which may be used in bumper
systems due to the low surface energy of the plastic materials. As
such it is believed adhesives have not hitherto been employed for
fabricating FECs, bumper systems and the like.
[0008] Adhesives for use in bonding to low surface energy materials
are however known. For example U.S. Pat. No. 5,795,657 discloses
adhesive compositions which are said to have excellent adhesion to
a variety of substrates especially low surface energy polymers. The
adhesive disclosed in this document relates to organoborane
polyamine complexes and especially complexes wherein the polyamine
is reaction product of dye primary amine terminated material and
material having at least two groups reactive with primary amine
with an excess of primary amine groups over groups reactive with
primary amine. The complexes may be used in systems that initiate
the polymerisation of acrylic monomer to yield acrylic adhesive
compositions. Such compositions are said to be useful for bonding
low surface energy plastic or polymer substrates U.S. Pat. No.
5,795,657 refers to organoborane amine complexes used in acrylic
adhesives and which may be employed in structural and
semi-structural applications including glass/metal bonding and
bonding other types of materials together. Reference is made to,
bonding plastic to a range of types of materials of which one is
metal.
PRIOR ART
[0009] U.S. Pat. No. 5,691,065 relates to organoborane amine
complexes and to acrylic adhesives that incorporate initiator
systems based on such complexes. The adhesives are especially
useful in bonding low surface energy substrates such as
polyethylene, polypropylene and polytetrafluoroethylene. In the
Examples in this document Examples 14 to 118 provide data
concerning adhesion to a polyethylene substrate or a
polytetrafluoro-ethylene substrate. Examples 121 to 125
additionally include reference to adhesion of a polypropylene
substrate which is bonded to a substrate of the same material.
[0010] These prior art documents do not contemplate the use of
adhesives to bond reinforcing components to plastic mouldings in
automobile applications in which a combination of practical and
technical criteria must be met. In particular, there is no
indication in these documents that adhesives may be employed in
FECs or bumper systems which, by the nature of their use, are
exposed to impact and high stresses and strains.
[0011] In view of the widespread consumer use of automobiles,
matters of safety, such as improved crash resistance, durability
and stiffness of the FEC and robustness, resistance to heat,
chemical inertness and recoverability in low speed impacts of
bumper systems, together with cost and manufacturing flexibility
are critical in the design and manufacture of automobiles.
[0012] The known technique of mechanical fixing of the reinforcing
member to the plastic structural member has drawbacks as regards
structural limitations, and stress concentrations and forming a
component, for example an FEC and a bumper system by moulding the
plastic in situ, for example through holes in the reinforcement, is
costly and inflexible which may limit design options and also
increase costs of production. Producing the components for use in
FECs and bumpers by in situ moulding around the reinforcement also
requires the moulding tool to have a complementary design to the
reinforcing component so any changes in the design of the
reinforcing component require modifications to the moulding tool
hence introducing further process complication and cost. A need
remains therefore to improve the optimum combination of safety,
cost and manufacturing flexibility.
SUMMARY OF THE INVENTION
[0013] We have now found a method by which the reinforcing member
may be attached to the plastic structural member in automobile
assemblies such as FECs and bumper systems which ameliorates or
removes the drawbacks associated with existing methods of producing
them. By employing certain types of adhesive which are capable of
bonding to low energy surfaces such as plastics materials used in
FECs and bumper systems, the need for attachment through mechanical
fixing or in situ formation of a plastic moulding around a
reinforcing component may be reduced or avoided.
[0014] Accordingly, a first aspect of the invention provides a
method for producing an automobile assembly comprising a structural
member made of a moulded plastics material having a low energy
surface and a reinforcing member attached to the structural member,
the members having complementary surfaces, which comprises applying
an adhesive to the complementary surface of the structural member
and/or reinforcing member, bringing the complementary surfaces of
the reinforcing member and structural member into contact and
allowing the adhesive to set so as to bond the structural member
and reinforcing member together wherein the adhesive is capable of
bonding to a low energy surface plastic.
[0015] By low energy surface plastic is meant materials that have a
surface energy of less than 45 mJ/m.sup.2, suitably less than 40
mJ/m.sup.2 and desirably less than 35 mJ/m.sup.2 including, by way
of example polypropylene and polyamide. If desired, the surface of
the structural member and/or reinforcing member may be treated or
primed to improve adhesion prior to application of the adhesive.
Suitably the structural member is not subjected to treatment or
priming and the adhesive is applied directly to the surface of the
structural member.
[0016] In a second aspect, the invention provides for the use of an
adhesive capable of bonding to a low energy surface substrate in
the fabrication of an automobile assembly which comprises a
structural member comprising a plastic moulding having a low energy
surface and a reinforcing member to bond together the said moulding
and reinforcing member.
[0017] In a third aspect, the invention provides an automobile
assembly comprising a structural member made of a moulded plastics
material having a low energy surface and a reinforcing member
attached to the structural member, the structural member and
reinforcing member having complementary surfaces and being attached
by means of an adhesive, which is capable of bonding to a low
energy surface substrate, on at least part of one or both of the
complementary surfaces.
[0018] The present invention may be applied to any automobile
assemblies in which a material is to be bonded to a low energy
surface material for example "front end" systems and "rear end"
systems and a bumper system.
[0019] Advantageously, the invention permits the structural member
and the reinforcing member to be attached after the structural
member has been produced so avoiding the drawbacks of the known
process in which the structural member is formed in situ. Thus the
risk of having to alter the tools for producing the structural
member if the reinforcing member design alters is reduced. Further,
the design and hence structural effectiveness of the reinforcing
member is not compromised by limitations on the geometry, shape or
dimensions of the reinforcing member imposed by the tooling
apparatus. The invention accordingly provides advantages as regards
enhanced process flexibility, design of the assembly and cost. In
addition reinforcements of a complex design may be employed to
provide a higher level of reinforcement per unit weight of
reinforcement. This arrangement may provide additional benefits as
regards design flexibility, reduced weight with the advantages that
flow from that.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The invention is described with reference to the
accompanying Figures in which:
[0021] FIG. 1 shows a perspective view of a structural member and a
reinforcing member prior to assembly.
[0022] FIG. 2 shows a perspective view of a part of a bonded
automobile assembly.
[0023] FIG. 3 shows a cross-section of the assembly of FIG. 2 as
shown at line B-B of FIG. 2.
[0024] FIG. 4 shows a cross-section of an alternative design of
assembly to that shown in FIG. 3.
[0025] FIGS. 5 to 8 show cross-section views of different examples
of bumper systems according to the invention.
[0026] FIGS. 9 to 11 show cross-section views of bumper systems in
which the bumper fascia and the bumper beam are connected through a
linking component.
[0027] FIG. 12 illustrates the placement of a FEC in an
automobile.
DETAILED DESCRIPTION OF THE INVENTION
[0028] In a preferred embodiment, the structural member and
reinforcing member have complementary shapes, at least in part and
they are bonded together by application of adhesive on either or
both of the complementary parts of the members so as to bond the
two parts together over an area which is significantly greater than
the area associated with joining the parts by mechanical fixing.
Advantageously, bonding the structural member and reinforcing
member in this manner reduces the concentration of stress at the
joints between the two members. Preferably, the structural member
and reinforcing member are bonded together by a continuum of
adhesive along the complementary surfaces on the two members in
order to reduce the concentration of stress at a particular point
when load is applied to the assembly.
[0029] The automobile assembly, for example a FEC and a bumper
system, is suitably manufactured employing known techniques for
producing the structural member for example compression or
injection moulding.
[0030] Suitably the structural member comprises a plastic moulding.
The plastics material preferably comprises a homopolymer, for
example a polyolefin, a polyamide, a polyphenylene oxide and
polystyrene, or a copolymer, for example a polyalkylene
terephthalate, having a low surface energy.
[0031] Preferred plastics materials include polypropylene,
polyamide, polyamide alloys, polyphenylene oxide polymers,
polyphenylene oxide alloys, polystyrene polymers, polystyrene
alloys, polybutylene terephthalate polymers and polybutylene
terephthalate alloys. The plastics material may contain fibre, for
example short glass fibre, long glass fibre, short natural fibre or
long natural fibre.
[0032] Especially preferred plastics materials include short glass
fibre filled polypropylene, long glass fibre filled polypropylene,
glass filled polyamide and glass filled polyamide alloys. Plastics
materials which are especially preferred for use in bumper systems
as the EAU include unfilled polypropylene, talc filled
polypropylene, mineral filled polypropylene
[0033] The reinforcing member is suitably made of a metal, for
example steel, zinc and aluminium, but may be made from other
materials capable of providing reinforcement. The reinforcing
member may be coated with materials typically employed in the
manufacture of automobiles, for example anti-corrosion materials
and primers for additional coatings such as paint.
[0034] In an especially preferred embodiment of the invention in
which the assembly is a FEC, the structural member is made from
glass filled polypropylene and/or glass filled polyamide and the
reinforcing member is made from steel or aluminium. In a further
preferred embodiment, the assembly is a bumper system and the
structural member is made from polypropylene and the reinforcing
member is made from steel, aluminium or polypropylene.
[0035] In a bumper system, the EAU is suitably disposed between the
bumper fascia and the bumper beam. The EAU preferably has a
generally "C" shaped cross-section. The open ends of the "C" shaped
EAU may be connected to the beam and the opposite side of the "C"
connected to the fascia or vice-versa by means of the adhesive.
Where the EAU is connected to the beam by means of the adhesive,
the EAU is the structural member and the beam the reinforcing
member. Where the EAU is connected to the fascia by means of the
adhesive, the fascia and EAU are for present purposes the
structural member and reinforcing member.
[0036] The reinforcing member and/or structural member may be
provided with contours or channels which are complementary with the
surface of the other member so as to provide improved contact and
alignment between the structural and reinforcing members. Shaping
the members suitably provides enhanced resistance to stresses as
the adhesion between the members may be supplemented by physical
abutment depending on the direction in which the stress is
applied.
[0037] The adhesive employed in the present invention must be able
to bond a low energy surface substrate and also act to bond a
second substrate to the low energy surface substrate and,
preferably is a polymerisable composition.
[0038] In a preferred method the structural member and reinforcing
member are bonded together by providing an adhesive comprising a
polymerisable composition, contacting together the components of
the adhesive under conditions for initiating polymerisation of the
adhesive, applying the adhesive to the complementary surface of the
structural and/or reinforcing member, bringing the complementary
surfaces of the reinforcing member and structural member into
contact and curing the adhesive so as to bond the said members
together. Initiating polymerisation of the adhesive may be carried
out prior to or after application of the adhesive to one or both
members or during application or as a result of application of the
adhesive to one or both members.
[0039] In a preferred embodiment, the adhesive comprises a
polymerisable composition comprising an organoborane/amine complex
and one or more of monomers, oligomers or polymers having olefinic
unsaturation which is capable of polymerisation by free radical
polymerisation. Optionally, the adhesive may additionally comprise
a compound which causes the said complex to disassociate so as to
release the borane to initiate polymerisation of one or more of
monomers, oligomers or polymers having olefinic unsaturation. Where
a compound which causes the complex to disassociate is employed, it
is kept separate from the complex until initiation of
polymerisation is desired. The polymerisable composition which
contains the disassociating agent may be cured at any desired
temperature, such as at, or near, ambient temperature and below
ambient temperature.
[0040] An especially preferred embodiment of the invention provides
an automobile assembly comprising a structural member made of a
moulded glass filled polypropylene and/or glass filled polyamide
having a surface energy of less than 45 mJ/m.sup.2, and a
reinforcing member made from steel, zinc and/or aluminium attached
to the structural member, the structural member and reinforcing
member having complementary surfaces and being attached by means of
an adhesive which is capable of bonding to a substrate having a
surface energy of less than 45 mJ/m.sup.2 disposed between at least
part of the complementary surfaces so as to bond them together, the
adhesive being derived from a polymerisable composition
comprising
[0041] i) an organoborane/amine complex;
[0042] ii) one or more of monomers, oligomers or polymers having
olefinic unsaturation which is capable of polymerisation by free
radical polymerisation; and, optionally
[0043] iii) a compound which causes the said complex to
disassociate so as to release the borane to initiate polymerisation
of one or more of monomers, oligomers or polymers having olefinic
unsaturation.
[0044] Additional especially preferred aspects of the invention are
a method of making the automobile assembly referred to in the
preceding paragraph and use of an adhesive described in that
paragraph in fabricating the assembly described in it.
[0045] Adhesives and polymerisable compositions disclosed in
International Patent Application No. PCT/US00/33806 are especially
preferred for use in the present invention to bond the structural
member and reinforcing member together.
[0046] The amines used to complex the organoborane compound can be
any amines which complex the organoborane and which can be
decomplexed when exposed to a decomplexing agent. Preferred amines
include the primary or secondary amines or polyamines containing
primary or secondary amine groups, or ammonia as disclosed in
Zharov U.S. Pat. No. 5,539,070 at column 5 lines 41 to 53,
incorporated herein by reference, Skoultchi U.S. Pat. No. 5,106,928
at column 2 line 29 to 58 incorporated herein by reference, and
Pocius U.S. Pat. No. 5,686,544 column 7, line 29 to Column 10 line
36 incorporated herein by reference; monthanolamine, secondary
dialkyl diamines or polyoxyalkylenepolyamines; and amine terminated
reaction products of diamines and compounds having two or more
groups reactive with amines as disclosed in Deviny U.S. Pat. No.
5,883,208 at column 7 line 30 to column 8 line 56, incorporated
herein by reference. With respect to the reaction products
described in Deviny the preferred diprimary amines include alkyl
diprimary amines, aryl diprimary amines, alkyaryl diprimary amines
and polyoxyalkylene diamines; and compounds reactive with amines
include compounds which contain two or more groups of carboxylic
acids, carboxylic acid esters, carboxylic acid halides, aldehydes,
epoxides, alcohols and acrylate groups. Preferred amines include
n-octylamine, 1,6-diaminohexane (1,6-hexane diamine), diethylamine,
dibutyl amine, diethylene triamine, dipropylene diamine,
1,3-propylene diamine (1,3-propane diamine), 1,2-propylene diamine,
1,2-ethane diamine, 1,5-pentane diamine, 1,12-dodecanediamine,
2-methyl-1,5-pentane diamine, 3-methyl-1,5-pentane diamine,
triethylene tetraamine, di ethylene triamine. Preferred
polyoxyalkylene polyamines include polyethyleneoxide diamine,
polypropyleneoxide diamine, triethylene glycol propylene diamine,
polytetramethyleneoxide diamine and
polyethyleneoxidecopolypropyleneoxide diamine.
[0047] In particular, the amine in the organoborane/amine complex
is suitably selected from the group of amines having an amidine
structural component; aliphatic heterocycles having at least one
nitrogen in the heterocyclic ring wherein the heterocyclic compound
may also contain one or more nitrogen atoms, oxygen atoms, sulphur
atoms, or double bonds in the heterocycle; primary amines which in
addition have one or more hydrogen bond accepting groups wherein
there are at least two carbon atoms, preferably at least three
carbon atoms, between the primary amine and the hydrogen bond
accepting group, such that due to inter- or intramolecular
interactions within the complex the strength of the B--N bond is
increased; and conjugated imines.
[0048] Preferred hydrogen bond accepting groups include the
following: primary amines, secondary amines, tertiary amines,
ethers, halogens, polyethers or polyamines. Heterocycle as used
herein refers to a compound having one or more aliphatic cyclic
rings of which one of the rings contains nitrogen. The amidines or
conjugated imines may be straight or branched chain or cyclic.
[0049] Desirably, the organoborane used in the complex is a
trialkyl borane or an alkyl cycloalkyl borane. Preferably this
borane corresponds to Formula 1:
B--(R.sup.1).sub.3 Formula 1
[0050] wherein B represents boron; and R.sup.1 is separately in
each occurrence a C.sub.1-10alkyl, C.sub.3-10cycloalkyl, or two or
more of R.sup.1 may combine to form a cycloaliphatic ring.
[0051] Preferably R.sup.1 is C.sub.1-4alkyl, even more preferably
C.sub.2-4alkyl and most preferably C.sub.3-4alkyl. Among preferred
organoboranes are tri-ethyl borane, tri-isopropyl borane and
tri-n-butylborane.
[0052] In a preferred embodiment, the amine part of the complex
comprises a compound having a primary amine and one or more
hydrogen bond accepting groups, wherein there are at least two
carbon atoms, preferably at least about three, between the primary
amine and hydrogen bond accepting groups.
[0053] Preferably, the amine corresponds to Formula 2:
NH.sub.2(CH.sub.2).sub.b(C(R.sup.2).sub.2).sub.oX (2)
[0054] wherein R.sup.2 is separately in each occurrence hydrogen or
a C.sub.1-10alkyl or C.sub.3-10cycloalkyl; X is hydrogen bond
accepting moiety; a is an integer of 1 to 10; and b is separately
in each occurrence an integer of 0 to 1, and the sum of a and b is
from 2 to 10.
[0055] Preferably R.sup.2 is hydrogen or methyl.
[0056] Preferably X is separately in each occurrence a hydrogen
accepting moiety and, when the hydrogen accepting moiety is an
amine, it is preferably a tertiary or a secondary anine. More
preferably X is separately in each occurrence --N(R.sup.8).sub.e,
--OR.sup.10, or a halogen wherein R.sup.8 is separately in each
occurrence, C.sub.1-10 alkyl, C.sub.3-10 cycloalkyl or
--(C(R.sup.2).sub.2).sub.d-W; R.sup.10 is separately in each
occurrence, C.sub.1-10 alkyl, C.sub.3-10 cycloalkyl, or
--(C(R.sup.2).sub.2).sub.d-W; and e is 0, 1, or 2. More preferably
X is --N(R.sup.8).sub.2 or --OR.sup.10.
[0057] Preferably, R.sup.8 and R.sup.10 are C.sub.1-4 alkyl or
--(C(R.sup.l).sub.2).sub.d-W, more preferably C.sub.1-4alkyl and
most preferably methyl. W is separately in each occurrence hydrogen
or C.sub.1-10 alkyl or X and more preferably hydrogen or C.sub.1-4
alkyl.
[0058] Preferably, a is about 1 or greater and more preferably 2 or
greater. Preferably a is about 6 or less, and most preferably about
4 or less. Preferably, b is about 1. Preferably, the sum of a and b
is an integer about 2 or greater and most preferably about 3 or
greater. Preferably the sum of a and b are about 6 or less and more
preferably about 4 or less. Preferably d is separately in each
occurrence an integer of 1 to 4, more preferably 2 to 4, and most
preferably 2 to 3.
[0059] Among preferred amines corresponding to Formula 2 are
dimethylaminopropyl amine, methoxypropyl amine,
dimethylaminoethylamine, dimethylaminobutylamine, methoxybutyl
amine, methoxyethyl anine, ethoxypropylamine, propoxypropylamine,
amine terminated polyalkylene ethers (such as trimethylolpropane
tris(poly(propyleneglycol), amine terminated)ether),
aminopropylmorpholine, isophoronediamine, and
aminopropylpropanediamine.
[0060] In another embodiment, the amine may be an aliphatic
heterocycle having at least one nitrogen in the heterocycle. The
heterocyclic compound may also contain one or more of nitrogen,
oxygen, sulfur or double bonds. In addition, the heterocycle may
comprise multiple rings wherein at least one of the rings has a
nitrogen in the ring. Preferred compounds of this type include
morpholine, piperidine, pyrolidine, piperazine, 1,3,3 trimethyl
6-azabicyclo[3,2,1] octane, thiazolidine, homopiperazine,
aziridine, 1,4-diazabicylo[2.2.2]octane (DABCO),
1-amino-4-methylpiperazine, and 3-pyrroline.
[0061] In yet another embodiment, the amine which is suitably
complexed with the organoborane is an amidine. Any compound with
amidine structure wherein the amidine has sufficient binding energy
as described hereinbefore with the organoborane, may be used. Among
preferred amidines are 1,8 diazabicyclo[5,4]undec-7-ene;
tetrahydropyrimidine; 2-methyl-2-imidazoline; and
1,1,3,3-tetramethylguanidine.
[0062] In a further embodiment, the amine which is complexed with
the organoborane is suitably a conjugated imine. Any compound with
a conjugated imine structure, wherein the imine has sufficient
binding energy with the organoborane as described in International
Patent Application No. PCT/US00/33806 may be used. The conjugated
imine can be a straight or branched chain imine or a cylic imine.
Among preferred conjugated imines are 4-dimethylaminopyridine;
2,3-bis(dimethylamino)cycl- opropeneimine;
3-(dimethylamine)acroleinimine; 3-(dimethylamino)methacrole-
inimine.
[0063] Preferably the molar ratio of amine compound to organoborane
compound is from 1.0:1.0 to 3.0:1.0. Below the ratio of about
1.0:1.0 there may be problems with polymerisation, stability of the
complex and adhesion. Greater than about a 3.0:1.0 ratio may be
used although there may not be additional benefit from using a
ratio greater than about 3.0:1.0. If too much amine is present,
this may negatively impact the stability of the adhesive or polymer
compositions. Preferably the molar ratio of amine compound to
organoborane compound is from 2.0:1.0 to 1.0:1.0.
[0064] The organoborane amine complex may be readily prepared using
known techniques, for example as described or referred to in
International Patent Application No. PCT/US00/33806.
[0065] Preferably, the polymerisable material comprises acrylate
and/or methacrylate based compounds. Especially preferred acrylate
and methacrylate compounds include methylmethacrylate,
butylmethacrylate, ethylhexylmethacrylate, isobornylmethacrylate,
tetrahydrofurfuryl methacrylate, and
cyclohexylmethylmethacrylate.
[0066] The polymerisable composition may further comprise an
effective amount of a compound that is reactive with an amine so as
to liberate the organoborane so as to initiate polymerisation (a
disassociating agent). Desirable amine reactive compounds are those
materials that can readily form reaction products with amines at or
below and more preferably at room temperature so as to provide a
composition that can be generally easily used and cured under
ambient conditions. General classes of these compounds include
acids, aldehydes, isocyanates,acid chlorides, sulphonyl chlorides,
mixtures thereof and the like. Preferred amine reactive compounds
are acids, especially Bronsted and Lewis acids and those described
in U.S. Pat. No. 5,718,977 and, more desirably acrylic acid and
methacrylic acid.
[0067] In the polymerisable composition, suitably at least 20% by
weight, preferably at least 30% by weight and especially at least
40% by weight of the composition comprises the polymerisable
component. Independently, the polymerisable component is suitably
present at a level not exceeding 95%, preferably not exceeding 90%
and especially not exceeding 85% by weight of the composition.
[0068] Suitably, the organoborane/amine complex is present at a
level of at least 0.2%, preferably at least 1% and more preferably
at least 2% by weight of the composition. Independently, the
complex is suitably present at a level not exceeding 8%, preferably
not exceeding 6% and especially not exceeding 4% by weight of the
composition.
[0069] If present, the disassociating compound is present at a
level of at least 1%, preferably at least 1.5% and more preferably
at least 2% by weight of the composition. Independently, the
disassociating compound is suitably present at a level not
exceeding 8%, preferably not exceeding 6% and especially not
exceeding 4% by weight of the composition.
[0070] bond between a 30% glass filled polypropylene structural
member and the reinforcing member without the structural member
having been subjected to any surface treatment when tested in
accordance with the procedure set out in ASTM D1002. Preferably,
the adhesive provides a bond when tested under this regime
including in addition being subjected to thermal cycling and high
humidity. Thermal cycling in this context suitably includes cycling
over a range from -40.degree. C. to greater than 120.degree. C.
Humidity levels can vary from dry to fully saturated.
[0071] The adhesive may be used in the manner set out in
International Patent Application No. PCT/US00/33806. Optionally,
further components may be included as additives in the composition.
Suitable additives include those set out in International Patent
Application No. PCT/US00/33806.
[0072] The assembly suitably is able to withstand exposure to heat
at a temperature of 100.degree. C. and suitably at up to
120.degree. C. or more. Further, the assembly desirably should also
be able to withstand loads applied during production and also
imposed in use, for example by slamming the bonnet, application of
load to the bonnet latch and vibration and fatigue during use due
to displacement from the road surface. The amount and location of
adhesive is suitably selected having regard to the design and
structure of the automobile to which the application applies.
[0073] In fabricating the assembly, the adhesive composition is
suitably applied to one or both of the members in those areas which
are to be joined. The adhesive is suitably cured at ambient
temperature and curing preferably is initiated prior to the members
being brought together. The members are then suitably contacted
while the adhesive remains able to bond the two members, for
example, as the adhesive becomes tacky. If desired, the members may
be held in place by mechanical means for example, snap-fits,
mechanical fasteners or temporary clips. The surfaces are suitably
clean and substantially free of foreign materials, for example
fats, oils and water. The complementary surfaces may become adhered
together relatively quickly so allowing the bonded assembly to be
handled, for example on an automobile production line. The adhesive
suitably continues to cure to provide maximum bond strength and
this may take a period of hours.
[0074] The process conditions employed in bonding the structural
member and reinforcing member together may vary according to the
specific adhesive employed.
[0075] By way of illustration only, an adhesive comprising methyl
methacrylate as the polymerisable component and an
organoborane/amine complex as herein described may be applied to a
structural member comprising polypropylene which has not been
pre-treated, mixed with a curing component and left for a period of
1 to 10 minutes, prior to bringing a steel reinforcing member
brought into contact with the structural member. The adhesive
suitably bonds the two members sufficiently within 10 to 30 minutes
after curing is initiated to allow the assembly to be handled.
Subsequently, the adhesive continues to cure to provide a bond of
maximum strength after 10 to 30 hours. The process is suitably
carried out at ambient temperature.
[0076] As desired, mechanical fixing may be employed in addition to
adhesive bonding to hold the structural member and the reinforcing
member together.
[0077] In FIG. 1, a structural member (1) and a reinforcing member
(2) are shown prior to bonding together in accordance with the
method of the invention. FIG. 2 shows the members (1) and (2)
bonded together after assembly.
[0078] The structural member (1) is made of a moulded plastics
material having a low energy surface and suitably is made of
polypropylene or polyamide and typically is produced by compression
moulding or injection moulding. The reinforcing member (2) is
typically made of steel or aluminium.
[0079] The structural member (1) and the reinforcing member (2) are
shaped as desired according to the design of the automobile and are
provided with complementary surfaces (3) and (4) such that the
members (1) and (2) fit snugly together and the invention enables
the members (1) and (2) to be assembled after being produced.
[0080] Adhesive is applied to part or all of the complementary
surface (3) and/or (4) and the reinforcing member (2) and the
structural member (1) are brought into contact by relative movement
towards each other in the direction A so that the complementary
surfaces (3) and (4) abut one another. The adhesive is then cured
or allowed to cure to provide a bonded assembly according to the
invention, a part of which is as shown in FIG. 2.
[0081] FIG. 2 indicates a plane B-B through which a cross-section
illustration is shown in FIG. 3. In FIG. 3, the reinforcing member
(2) has a shallow channel (5) the inside of which defines the
complementary surface (4) into which the complementary surface (3)
of the structural member (1) is located in manufacturing the
assembly. Adhesive is placed on at least part of the complementary
surface (3) and/or (4) prior to assembly and forms the bond by
which the members (1) and (2) are adhered.
[0082] The structural member (1) is also provided with side
channels (6) and (7) and the reinforcing member (2) is provided
with lips (8) and (9) which engage with the side channels (6) and
(7) in a complementary manner. The surfaces of the channels (6) and
(7) and lips (8) and (9) may be bonded by the provision of adhesive
between the respective surfaces. Alternatively, these surfaces may
not be bonded but in any event provide physical abutment between
the respective parts of the structural member (1) and the
reinforcing member (2) to enhance resistance to impact in the
direction C, that is from the front of the automobile and to
provide improved alignment between the members (1) and (2) during
assembly.
[0083] FIG. 4 shows a cross section of an assembly according to the
invention of a different design to that shown in FIG. 3. The
structural member (1) and the reinforcing member (2) are aligned
and adhered along complementary surfaces (3) and (4). Physical
abutment of the members (1) and (2) along lips (10) and (11) and
(12) and (13) respectively provide enhanced resistance to
impact.
[0084] FIGS. 5 to 8 show a structural member (14) of different
design in each case bonded to a reinforcing member (15) by means of
adhesive (16) capable of bonding to a low surface energy plastics
material. The structural member (14) is made of a plastics
materials having a low energy surface and suitably is made of
polypropylene or polyamide. In FIG. 5, the structural member (14)
is a generally "C" shaped EAU and in FIG. 7 the structural member
(14) is a blow moulding and in FIG. 8 it is an injection
moulding.
[0085] The reinforcing member (15) is typically made of steel or
steel and aluminium or may be made of plastics material. In FIG. 6
the reinforcing member (15) is a so-called "close-out" member which
means that the member (15) is disposed across the open ends of the
"C" shaped member (14) so as to form a box cross section.
[0086] The structural member (14) may have lips (17) as shown in
FIGS. 5 and 8 and the adhesive (16) maybe applied to the lips (17)
on or to the reinforcing member (15) at the required location. The
adhesive (16) is preferably applied to either or both the
structural member (14) and reinforcing member (15) at all points at
which they are in contact. Alternatively, the reinforcing member
(15) may have lips (18) to which adhesive (16) is applied and which
are then contacted with the structural member (14) as illustrated
in FIG. 6 or, as shown in FIG. 7, neither the reinforcing member
(15) nor the structural member (14) need have lips.
[0087] FIGS. 9 to 11 show a structural member (14) connected to a
reinforcing member (15) by means of an adhesive (16) which
preferably is employed along the length of the members (14) and
(15). In FIG. 9, the structural member(14) is an EAU and is made of
a polypropylene moulding. The bumper fascia (19) is spaced apart
from member (14) and connected through conventional means to
another part of the vehicle (not shown).
[0088] In FIGS. 10 and 11, the bumper fascia is the structural
member (14). The "C" shaped EAU is the reinforcing member (15) and
is made of steel. The member (15) is spaced apart from the bumper
beam (20). The member (15) is bonded to the bumper fascia (14).
[0089] Suitably, the generally "C" shaped component as illustrated
in FIG. 9 (structural member (14)) and FIGS. 10 and 11 (reinforcing
member (15)) provides excellent impact resistance properties. Once
assembled, the open end of the "C" section is closed by being
bonded to the reinforcing member (15) in FIG. 9, the bumper fascia
(19) in FIG. 10 and is located next to, but not bonded to, the
bumper beam (20) in FIG. 11 so creating a closed box section. The
thickness of the box section and the thickness of the walls
defining the box section determine the stiffness of the assembly
and the performance of the assembly under impact. The horizontal
walls, that is the top and bottom part of the "C" shaped component
may be designed to buckle under a certain load. This enables the
impact resistance of the assembly to be tailored according to the
intended use. The height of the box section, that is the length of
the back part of the "C" shaped component may be tailored to
provide desired properties according to the intended use.
[0090] Use of an EAU having a "C" shaped cross section is
especially advantageous in that the box shaped cross section formed
on assembling the bumper system possesses excellent strength
characteristics when subjected to impact.
* * * * *