U.S. patent application number 16/363574 was filed with the patent office on 2019-07-18 for bonding dissimilar materials with adhesive paste.
The applicant listed for this patent is Zephyros, Inc.. Invention is credited to Jeanne Bednarski, Renee Bradley, David Sheasley.
Application Number | 20190218435 16/363574 |
Document ID | / |
Family ID | 50792600 |
Filed Date | 2019-07-18 |
United States Patent
Application |
20190218435 |
Kind Code |
A1 |
Bradley; Renee ; et
al. |
July 18, 2019 |
Bonding Dissimilar Materials with Adhesive Paste
Abstract
A rivetable adhesive for use in a joint between dissimilar
materials, comprising a Nquid epoxy resin, an expoxidized
polysulfide, a flexibilizer, a solid epoxy CTBN adduct based upon
bisphenol A, a prienoxy resin, an impact modifier including
methacrylate-butadiene-styrene, a curing agent; and a blowing
agent. The adhesive finds particular suitability for use in
riveting aluminum panels to steel structures, such as for forming
automotive vehicle roof structures.
Inventors: |
Bradley; Renee; (St. Clair,
MI) ; Sheasley; David; (Rochester, MI) ;
Bednarski; Jeanne; (Ray Township, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Zephyros, Inc. |
Romeo |
MI |
US |
|
|
Family ID: |
50792600 |
Appl. No.: |
16/363574 |
Filed: |
March 25, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14787080 |
Oct 26, 2015 |
10240075 |
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PCT/US2014/035473 |
Apr 25, 2014 |
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16363574 |
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61816394 |
Apr 26, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08L 9/02 20130101; C08G
59/186 20130101; C09J 9/00 20130101; C08L 81/04 20130101; C09J
2451/00 20130101; C09J 2463/00 20130101; C09J 11/08 20130101; C08L
51/04 20130101; C08L 71/123 20130101; C09J 2471/00 20130101; C09J
5/08 20130101; C09J 163/00 20130101; C09J 2475/00 20130101; C09J
163/00 20130101; C09J 171/00 20130101; C08L 81/04 20130101; C08L
51/04 20130101; C08L 71/123 20130101; C08L 9/02 20130101 |
International
Class: |
C09J 171/00 20060101
C09J171/00; C08L 81/04 20060101 C08L081/04; C08L 71/12 20060101
C08L071/12; C08L 51/04 20060101 C08L051/04; C08L 9/02 20060101
C08L009/02; C09J 11/08 20060101 C09J011/08; C09J 163/00 20060101
C09J163/00; C09J 5/08 20060101 C09J005/08; C09J 9/00 20060101
C09J009/00 |
Claims
1. An automotive vehicle assembly comprising: a support structure;
an aluminum panel adjacent the support structure; at least one
rivet joining the support structure to the aluminum panel; a
rivetable adhesive located in between the support structure and the
aluminum panel, the adhesive comprising: a. a liquid epoxy resin;
b. an epoxidized polysulfide; c. a flexibilizer; d. a solid epoxy
CTBN adduct based upon bisphenol A; e. a phenoxy resin; f. an
impact modifier including methacrylate-butadiene-styrene; g. a
curing agent; and h. a blowing agent; wherein the adhesive exhibits
a capillary viscosity of below 1000 PaS for a shear rate of 100
sec-1 or higher at a temperature of 70 or 90.degree. C. such that
the viscosity facilitates robotic application such that the
adhesive is heated to be applied above room temperature, but below
a temperature at which it would be activated for curing, expanding
or both curing and expanding.
2. The assembly of claim 1, wherein the liquid epoxy resin has an
epoxide equivalent weight (g/eq) per ASTM D-1652-11e1 of about
182-192.
3. The assembly of claim 1, wherein the impact modifier is a core
shell impact modifier.
4. The assembly of claim 1, including an aromatic substituted urea
curing accelerator.
5. The assembly of claim 2, wherein the blowing agent has a
decomposition temperature of about 190 to 220.degree. C.
6. The assembly of claim 3, wherein the liquid epoxy resin is a
resin reaction product of epichlorohydrin and bisphenol A having an
epoxide equivalent weight per ASTM D-1652-11e1 of about 182 to
about 192.
7. The assembly of claim 1, wherein the liquid epoxy resin is
present in an amount of about 15 to about 25 parts by weight of the
adhesive.
8. The assembly of claim 7, wherein the adhesive includes a liquid
epoxy resin reaction product of an epichlorohydrin and a
polypropylene glycol.
9. The assembly of claim 8, wherein liquid epoxy resin reaction
product of an epichlorohydrin and a polypropylene glycol is present
in amount of about 3 to about 20 parts by weight of the
adhesive.
10. The assembly of claim 1, wherein the flexibilizer is present in
an amount of about 1 to about 5 parts by weight of the
adhesive.
11. The assembly of claim 1, wherein the impact modifier is present
in an amount of about 15 to about 25 parts by weight of the
adhesive.
12. The assembly of claim 11, wherein the solid epoxy CTBN adduct
based upon bisphenol A is present in an amount of about 3 to about
15 parts by weight of the adhesive.
13. The assembly of claim 1, wherein the phenoxy resin is present
in an amount of about 15 to about 30 parts by weight of the
adhesive.
14. (canceled)
15. The assembly of claim 1, wherein the adhesive includes about
0.5 to about 5 parts by weight of calcined kaolin.
16-20. (canceled)
21. The assembly of claim 1, wherein the adhesive is applied to one
or more of the support structure and aluminum panel via a robotic
arm and applicator.
22. The assembly of claim 1, wherein the support structure
comprises a steel material.
23. The assembly of claim 22, wherein the adhesive is heated to a
first temperature during application and heated to a second
temperature during an automotive assembly process to cure.
24. The assembly of claim 23, wherein the first temperature is
lower than the second temperature.
25. The assembly of claim 23, wherein the adhesive foams upon
exposure to the second temperature.
26. The assembly of claim 1, wherein the adhesive substantially
prevents galvanic corrosion where the support and aluminum panel
are connected.
Description
TECHNICAL FIELD
[0001] The present invention pertains generally to adhesives and
more particularly to paste adhesives for bonding dissimilar
materials (e.g., steel and aluminum) in automotive vehicle
structures.
BACKGROUND
[0002] In the automotive vehicle field there is an ongoing need for
reducing weight of vehicle components. Traditionally, many vehicle
body components have been made from steel. Joining such parts
typically has been done by welding. In recent years, vehicle
manufacturers have sought to substitute other materials for steel.
For example, due to its relatively high strength to weight ratio,
aluminum has been examined as a substitute material. When steel and
aluminum are employed in combination, unfortunately, welding is an
impractical solution. There is thus a need for forming a relatively
high integrity joint between steel and aluminum for such
applications.
[0003] One particular application that involves forming joints
between steel and aluminum is the formation of vehicle roof
structures. For these structures, efforts have been made to join an
aluminum roof panel structure to a steel frame structure using
rivets. When aluminum is attached to steel using rivets as
mechanical fasteners, and the assembly is subjected to thermal
cycling (such as under paint bake conditions), there results a
potential for distortion of the assembly due to differing
coefficients of thermal expansion. For instance, the aluminum
experiences a bowing effect that increases any gap that may exist
between aluminum and steel components.
[0004] Efforts have been made to employ pumpable adhesives between
steel and aluminum. By their nature, pumpable adhesives tend to
have a relatively low viscosity. As a result, when employed between
steel and aluminum, there is a propensity for the steel and
aluminum to come into contact with each other during riveting. This
creates the potential for galvanic cohesion at the points of
contact. Such adhesives also have made it necessary in some
instances to employ secondary applications of sealant for assuring
moisture protection at the joints.
[0005] What is needed is an adhesive and system for applying it
that has characteristics sufficient for allowing riveting while
still maintaining a separation between the steel and aluminum
components during riveting.
SUMMARY OF THE INVENTION
[0006] The teachings herein meet the above need by providing an
improved adhesive and a method for robotically applying the
adhesive. Though the teachings find application in riveting
aluminum roof panels to steel frames, other applications are
possible as well. As can be appreciated, the teachings herein
provide a way to avoid galvanic corrosion between aluminum and
steel when those materials are riveted in an assembly. The
teachings herein also provide for assuring that a bond is
maintained between aluminum and steel structures during thermal
cycling (e.g., as part of a paint bake operation), which would
otherwise cause the aluminum and steel to separate from each other.
As a result, it is possible to achieve good water sealing
performance in the resulting assemblies during paint bake
operations, and the need for subsequent sealing operations can be
avoided.
[0007] The advantages herein are made possible by the use of a
paste adhesive that is thermally activatable to expand and fill any
gaps between aluminum and steel components during a paint bake
operation.
[0008] In one aspect the teachings envision a rivetable adhesive
for use in a joint between dissimilar materials, comprising a
liquid epoxy resin, an expoxidized polysulfide, a flexibilizer, a
solid epoxy CTBN adduct based upon bisphenol A, a phenoxy resin, an
impact modifier including methacrylate-butadiene-styrene, a curing
agent; and a blowing agent.
[0009] In a more specific example, the teachings herein contemplate
a rivetable adhesive for use in a joint between dissimilar
materials, comprising an admixture of about 15 to about 25 parts by
weight of a liquid epoxy resin reaction product of epichlorohydrin
and bisphenol A having an epoxide equivalent weight per ASTM
D-1652-11e1 of about 182 to about 192; about 10 to about 20 parts
by weight of an epoxidized pofysulfide; about 3 to about 20 parts
by weight of a liquid epoxy resin reaction product of an
epichlorohydrin and a polypropylene glycol; about 1 to about 5
parts by weight of a flexibilizer; about 3 to about 15 parts by
weight of a solid epoxy carboxyl terminated butadiene-acrylonitrile
(CTBN) adduct based upon bisphenol A; about 15 to about 25 parts by
weight of an impact modifier of methacrylate-butadiene-styrene;
about 15 to about 30 parts by weight of phenoxy resin; about 1 to
about 5 parts by weight of a dicyandiamide curing agent; an
aromatic substituted urea curing agent accelerator in an amount of
about 0.3 to about 1 parts by weight; and a blowing agent having a
decomposition temperature of about 190 to about 220.degree. C.
[0010] The adhesives herein may be robotically applied to a
substrate. For example, the adhesives may be applied to a steel
structure, an aluminum structure or both (or between some other
combination of dissimilar materials), and the structures may be
bonded together with the adhesive (e.g., after subjecting the
adhesive to heat from a paint bake operation as described herein).
A rivet may join the dissimilar materials.
DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 illustrates performance data in accordance with the
present teachings.
DETAILED DESCRIPTION
[0012] This application claims the benefit of the filing date of
U.S. Provisional Application Ser. No. 61/816,304 filed Apr. 26,
2013, the contents of such application being hereby incorporated by
reference for all purposes.
[0013] The explanations and illustrations presented herein are
intended to acquaint others skilled in the art with the teachings,
its principles, and its practical application. Those skilled in the
art may adapt and apply the teachings to its numerous forms, as may
be best suited to the requirements of a particular use.
Accordingly, the specific embodiments of the present teachings as
set forth are not intended as being exhaustive or limiting of the
teachings. The scope of the teachings should, therefore, be
determined not with reference to the above description but should
instead be determined with reference to the appended claims, along
with the full scope of equivalents to which such claims are
entitled. The disclosures of all articles and references, including
patent applications and publications, are incorporated by reference
for all purposes. Other combinations are also possible as will be
gleaned from the following claims, which are also hereby
incorporated by reference into this written description.
[0014] The teachings herein make advantageous use of an improved
composition for bonding dissimilar materials, and particularly for
bonding steel and aluminum. The teachings herein also make
advantageous use of an improved method for bonding dissimilar
materials, where the method employs robotic application of a paste
adhesive between components (e.g., components made of dissimilar
materials, such as steel and aluminum) to be joined. Use of a rivet
for joining is also contemplated.
[0015] The adhesive material may be a polymeric material that is
activated to flow, seal, expand or any combination thereof. It may
be a material that forms a foam (e.g., an acoustic foam or a
structural foam). It may expand from its original volume to at
least 50%, or even at least about 100% in the range of about 80 to
about 100%) or larger of its original volume.
[0016] The adhesive material may be applied through a die
associated with a robot arm, it may be applied at about room
temperature. The adhesive may be heated to be applied above room
temperature, but below a temperature at which it would be activated
for curing, expanding or both.
[0017] The adhesive material may be activated when subjected to
heat during paint shop baking operations. In applications where the
adhesive material is a heat activated, thermally expanding
material, an important consideration involved with the selection
and formulation of the material comprising the adhesive material is
the temperature at which a material reaction or expansion, and
possibly curing, will take place. For instance, in most
applications, it is undesirable for the material to be reactive at
room temperature or otherwise at the ambient temperature in a
production line environment. More typically, the adhesive material
becomes reactive at higher processing temperatures, such as those
encountered in an automobile assembly plant, when the material is
processed along with the automobile components at elevated
temperatures or at higher applied energy levels, e.g., during paint
or e-coat curing or baking steps. While temperatures encountered in
an automobile assembly operation may be in the range of about
148.89.degree. C. to 204.44.degree. C. (about 300.degree. F. to
400.degree. F.), body and paint shop applications are commonly
about 93.33.degree. C. (about 200.degree. F.) or slightly higher.
Following activation of the adhesive material, the material will
typically cure. Thus, it may be possible that the adhesive material
may be heated, it may then expand, and may thereafter cure to form
a resulting foamed material.
EXAMPLES
[0018] Among the following examples are examples that illustrate
materials that may are rivetable and exhibit attractive
characteristics for the present application. The amounts shown are
in preferred parts by weight. The teachings herein contemplate such
amounts as well as amounts that are +/-10%, 20%, 30%, 40% or even
50% of those shown. Examples 2 and 3 exhibit particularly
attractive viscosity characteristics and exhibit good riveting
characteristics. Example 1 is included by way of comparison. The
compositions need not necessarily employ the specific commercial
examples as set forth in the following Table 1. The compositions
may employ the general components as described in the following
Table 1. The composition may employ ingredients that exhibit the
characteristics set forth in the following Table 1. Even if not
explicitly specified, relative proportions of ingredients are
within the scope of the teachings herein.
TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Commercial (in
parts by (in parts by (in parts by Component Characteristic Example
weight) weight) weight) Liquid epoxy resin Epoxide DER 331 -- 16.48
20.60 reaction product equivalent from The of epichlorohydrin
weight (g/eq) Dow and bisphenol A per ASTM D- Chemical 1652 of
about Company 182-192 Expoxidized Epoxide Thioplast 8.00 17.01
15.36 Polysulfide equivalent EPS-350 including epoxy weight (g/eq)
from Akzo terminated per ASTM D- Nobel polymer with 1652-11e1 of
diglycidyl ether of about 320 bisphenol A and chains with
polysulfide Liquid epoxy resin Epoxide DER 732 6.70 6.70 12.92
reaction product equivalent from The of epichlorohydrin weight
(g/eq) Dow and per ASTM D- Chemical polypropylene 1652-11e1 of
Company glycol about 310-330 Flexibilizer Polyurethane DY 965 from
2.60 2.50 2.25 polyol Huntsman Solid epoxy resin Epoxide DER 662
11.00 -- -- reaction product equivalent from The of epichlorohydrin
weight (g/eq) Dow and bisphenol A per ASTM D- Chemical 1652-11e1 of
Company about 590-630 Solid epoxy Epoxide Araldite 16.00 5.00 4.52
carboxyl equivalent 1522 ES terminated weight (g/eq) butadiene- per
ASTM D- acrylontirile 1652-11e1 of (CTBN) adduct about 1560-1820
based upon bisphehol A Impact modifier of Paraloid 20.98 20.98
18.73 methacrylate- 2691A from butadiene-styrene the Dow
(core-shell) Chemical company Phenoxy Resin TMEP-70 24.77 24.77
19.35 from Springfield Indus. Dicyandiamide Dycanex 2.85 3.40 3.40
curing agent 1400B from Air Products Aromatic Melting point Omicure
U- 0.76 0.76 0.69 substituted urea of 220-230.degree. C. 52M from
curing accelerator Emerald (e.g., [4,4'- Methylene bis (Phenyl
Dimethyl Urea]) Calcined kaolin pH of about 6 Satintone W 5.49 1.47
1.25 and average from BASF particle size of about 1.3 .mu.m Blowing
agent of Decomposition Celogen 0.90 -- -- Activated temperature of
754A from azodicarbonamide about 165 to Lion 180.degree. C.
Copolymer Blowing agent of Decomposition Celogen AZ- -- 0.90 0.90
Activated temperature of 120 from azodicarbonamide about 190 to
Lion 220.degree. C. Copolymer Colorant Pigment 0.05 0.03 0.03
[0019] FIG. 1 illustrates capillary viscosity data obtainable using
the compositions of the teachings herein. As seen, the Example 1
formulation has a much higher viscosity than the viscosity of the
Example 2 and 3 formulations. Two different test temperatures are
used to cover the range of viscosities among the three materials.
The reference test method for capillary viscosity employed is ASTM
D 3835-08, pursuant to which the test parameters for the
capillaries are as follows: diameter=1 mm, length=16 mm.
[0020] As seen from FIG. 1, Examples 2 and 3 exhibit a capillary
viscosity well below 1000 PaS at temperatures of 70 or 90.degree.
C. and a shear rate (sec-1) of 200 or higher. For use herein, it is
desirable for materials to exhibit a capillary viscosity in the
range of about 100 to about 700 PaS for a shear rate (sec-1) of
about 100 to about 1000 at a temperature of 70 or 90.degree. C. For
example, it is desirable for materials to exhibit a capillary
viscosity in the range of about 100 to about 700 PaS for a shear
rate (sec-1) of about 100 to about 1000 at a temperature of 70 or
90.degree. C. Materials may exhibit a capillary viscosity in the
range of about 100 to about 400 PaS for a shear rate (sec-1) of
about 400 to about 1000 at a temperature of 70 or 90.degree. C. For
certain applications it is desirable that the materials (at 70 or
90.degree. C.) will have a capillary viscosity at shear rate
(sec-1) in the range of about 200 to about 400 that is less then
700 PaS, or even less than 500 PaS. The materials (at 70 or
90.degree. C.) will typically exhibit a capillary viscosity of at
least about 100 PaS at a shear rate (Sec-1) of about 200 to about
1000.
[0021] As used herein, unless, otherwise stated, the teachings
envision that any member of a genus (list) may be excluded from the
genus; and/or any member of a Markush grouping may be excluded from
the grouping.
[0022] Unless otherwise stated, any numerical values recited herein
include all values from the lower value to the upper value in
increments of one unit provided that there is a separation of at
least 2 units between any lower value and any higher value. As an
example, if it is stated that the amount of a component, a
property, or a value of a process variable such as, for example,
temperature, pressure, time and the like is, for example, from 1 to
90, preferably from 20 to 80, more preferably from 30 to 70, it is
intended that intermediate range values such as (for example, 15 to
85, 22 to 68, 43 to 51, 30 to 32 etc.) are within the teachings of
this specification. Likewise, individual intermediate values are
also within the present teachings. For values which are less than
one, one unit is considered to be 0.0001, 0.001, 0.01 or 0.1 as
appropriate. These are only examples of what is specifically
intended and all possible combinations of numerical values between
the lowest value and the highest value enumerated are to be
considered to be expressly stated in this application in a similar
manner. As can be seen, the teaching of amounts expressed as "parts
by weight" herein also contemplates the same ranges expressed in
terms of percent by weight. Thus, an expression in the of a range
in terms of "x parts by weight of the resulting polymeric blend
composition" also contemplates a teaching of ranges of same recited
amount of "x" in percent by weight of the resulting polymeric blend
composition."
[0023] Unless otherwise stated, all ranges include both endpoints
and all numbers between the endpoints. The use of "about" or
"approximately" in connection with a range applies to both ends of
the range. Thus, "about 20 to 30" is intended to cover "about 20 to
about 30", inclusive of at least the specified endpoints.
[0024] The disclosures of all articles and references, including
patent applications and publications, are incorporated by reference
for all purposes. The term "consisting essentially of to describe a
combination shall include the elements, ingredients, components or
steps identified, and such other elements ingredients, components
or steps that do not materially affect the basic and novel
characteristics of the combination. The use of the terms
"comprising" or "including" to describe combinations of elements,
ingredients, components or steps herein also contemplates
embodiments that consist of, or consist essentially of the
elements, ingredients, components or steps.
[0025] Plural elements, ingredients, components or steps can be
provided by a single integrated element, ingredient, component or
step. Alternatively, a single integrated element, ingredient,
component or step might be divided into separate plural elements,
ingredients, components or steps. The disclosure of "a" or "one" to
describe an element, ingredient, component or step is not intended
to foreclose additional elements, ingredients, components or
steps.
[0026] It is understood that the above description is intended to
be illustrative and not restrictive. Many embodiments as well as
many applications besides the examples provided will be apparent to
those of skill in the art upon reading the above description. The
scope of the invention should, therefore, be determined not with
reference to the above description, but should instead be
determined with reference to the appended claims, along with the
full scope of equivalents to which such claims are entitled. The
disclosures of all articles and references, including patent
applications and publications, are incorporated by reference for
all purposes. The omission in the following claims of any aspect of
subject matter that is disclosed herein is not a disclaimer of such
subject matter, nor should it be regarded that the inventors did
not consider such subject matter to be part of the disclosed
inventive subject matter.
* * * * *