U.S. patent application number 11/627449 was filed with the patent office on 2007-05-24 for expandable material.
This patent application is currently assigned to L&L Products, Inc.. Invention is credited to Jeffrey Apfel, Matthew Harthcock, Abraham Kassa.
Application Number | 20070117874 11/627449 |
Document ID | / |
Family ID | 33544601 |
Filed Date | 2007-05-24 |
United States Patent
Application |
20070117874 |
Kind Code |
A1 |
Kassa; Abraham ; et
al. |
May 24, 2007 |
EXPANDABLE MATERIAL
Abstract
An expandable material and articles incorporating the same are
disclosed. The material includes a polymeric admixture; a blowing
agent; a curing agent; a tackifier; and optionally, a filler or
fiber.
Inventors: |
Kassa; Abraham; (Shelby
Township, MI) ; Harthcock; Matthew; (Oakland
Township, MI) ; Apfel; Jeffrey; (Shelby Township,
MI) |
Correspondence
Address: |
DOBRUSIN & THENNISCH PC
29 W LAWRENCE ST
SUITE 210
PONTIAC
MI
48342
US
|
Assignee: |
L&L Products, Inc.
Romeo
MI
48065
|
Family ID: |
33544601 |
Appl. No.: |
11/627449 |
Filed: |
January 26, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10867835 |
Jun 15, 2004 |
7199165 |
|
|
11627449 |
Jan 26, 2007 |
|
|
|
60482897 |
Jun 26, 2003 |
|
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Current U.S.
Class: |
521/92 |
Current CPC
Class: |
C08J 2423/08 20130101;
C08J 2201/026 20130101; C08J 2333/06 20130101; C08J 2331/00
20130101; C08J 2207/02 20130101; C08J 2431/00 20130101; C08J 9/103
20130101; C08J 9/0061 20130101 |
Class at
Publication: |
521/092 |
International
Class: |
C08J 9/00 20060101
C08J009/00 |
Claims
1-24. (canceled)
25. A method of providing baffling or sealing to an article of
manufacture, comprising: intermixing ingredients to form an
expandable material, the ingredients including a curing, a blowing
agent and an acetate, an acrylate or both; applying the expandable
material to a structure of the article of manufacture; and
activating the expandable material to expand and form a foam, the
foam having a volume that is at least 1500% greater than the volume
of the expandable material in an unexpanded state; wherein the foam
provides sealing, baffling or both to the structure of the article
of manufacture.
26. A method as in claim 25 wherein the expandable material is
activated upon exposure to an elevated temperature and the
expandable material expands to a volume that is at least 2000%
greater than the volume of the expandable material in an unexpanded
state.
27. A method as in claim 25 wherein the curing agent includes a
peroxide curing agent having an activation temperature between
about 60.degree. C. and about 110.degree. C.
28. A method as in claim 25 wherein the expandable material include
one or more fillers and the one or more fillers include a fibrous
filler material.
29. A method as in claim 25 wherein the acrylate, the acetate or
both are part of a polymeric admixture that is at least about 40%
by weight of the expandable material and wherein the acrylate
comprises about 20% to about 95% of the polymeric admixture and the
acetate comprises about 5% to about 50% of the polymeric
admixture.
30. A method as in claim 25 wherein the expandable material
includes EVA and oxide and the blowing agent includes
4,4.sub.i-oxy-bis-(benzenesulphonylhydrazide), azodicarbonamide or
both.
31. A method as in claim 30 wherein the oxide includes a metal
oxide.
32. A method as in claim 25 wherein the expandable material
includes up to about 20% by weight epoxy resin.
33. A method as in claim 25 wherein the blowing agent, blowing
agent accelerator or both are at least 5.5% by weight of the
expandable material.
34. A method as in claim 25 wherein the blowing agent, blowing
agent accelerator or both are at least 8.0% by weight of the
expandable material.
35. A method of providing baffling to an automotive vehicle,
comprising: intermixing ingredients to form an expandable material,
the ingredients including curing agent, blowing agent and an
acetate, an acrylate or both; applying the expandable material to a
structure of the article of manufacture such that the material is
within a cavity defined by the automotive vehicle; and activating
the expandable material to expand and form a foam, the foam having
a volume that is at least 2000% greater than the volume of the
expandable material in an unexpanded state; wherein: i. the foam
provides baffling or both to the structure of the automotive
vehicle; ii. the expandable material is activated upon exposure to
temperatures encountered in a coating operation of automotive
assembly.
36. A method as in claim 35 wherein the expandable material expands
to a volume that is at least 3000% greater than the volume of the
expandable material in an unexpanded state.
37. A method as in claim 35 wherein the curing agent includes at
least one curing agent having an activation temperature between
about 60.degree. C. and about 110.degree. C.
38. A method as in claim 35 wherein the expandable material
includes one or more fillers and the one or more fillers include a
fibrous filler material.
39. A method as in claim 35 wherein the acrylate, the acetate or
both are part of a polymeric admixture that is at least about 40%
by weight of the expandable material and wherein the acrylate
comprises about 20% to about 95% of the polymeric admixture and the
acetate comprises about 5% to about 50% of the polymeric
admixture.
40. A method as in claim 35 wherein the expandable material
includes up to about 20% by weight epoxy resin.
41. A method as in claim 35 wherein the blowing agent, blowing
agent accelerator or both are at least 5.5% by weight of the
expandable material.
42. A method as in claim 35 wherein the blowing agent, blowing
agent accelerator or both are at least 8.0% by weight of the
expandable material.
43. A method of providing baffling to an automotive vehicle,
comprising: intermixing ingredients to form an expandable material,
the ingredients including curing agent, blowing agent, fiber and
EMA, EVA or both wherein the curing agent includes a peroxide
wherein the blowing agent, blowing agent accelerator or both are at
least 5.5% by weight of the expandable material; applying the
expandable material to a structure of the article of manufacture
such that the material is within a cavity defined by the automotive
vehicle; and activating the expandable material to expand and form
a foam, the foam having a volume that is at least 2000% greater
than the volume of the expandable material in an unexpanded state;
wherein: i. the foam provides baffling or both to the structure of
the automotive vehicle; ii. the expandable material is activated at
temperatures encountered in a coating operation during automotive
assembly; and iii. the expandable material includes up to about 20%
by weight epoxy resin.
44. A method as in claim 43 wherein the expandable material
includes a fibrous filler material.
Description
[0001] The present application claims the benefit of the filing
date of U.S. Provisional Application Ser. No. 60/482,897, filed
Jun. 26, 2003, hereby incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention relates generally to an expandable
material. More preferably, the present invention relates to an
expandable material that exhibits a property such as substantially
homogeneous expansion, a high level of expansion, improved
cohesiveness, a combination thereof or the like.
BACKGROUND OF THE INVENTION
[0003] For many years, industry has been concerned with designing
materials such as adhesives, baffle materials, structural materials
or the like, which exhibit desired characteristics. As examples,
the transportation industry and, particularly, the automotive
industry has been concerned with designing expandable materials
that exhibit characteristics such as low weight, good adhesion,
sound absorption, sound damping, relatively high levels of
expansion, homogeneous expansion, consistent or predictable
expansion or other desired characteristics. Design of such
materials with two or more of these characteristics can present
difficulties however. For example, it can be difficult to provide
an expandable material that exhibits a relatively high level of
expansion without sacrificing characteristics such as adhesion,
homogeneity of expansion or the like. Thus, the present invention
seeks to provide an expandable material that exhibits at least one
desired characteristic without significantly sacrificing the
presence of at least one other desired characteristic.
SUMMARY OF THE INVENTION
[0004] Accordingly, the present invention provides an expandable
material, which may be employed for sealing, baffling, reinforcing,
structural bonding or the like of a variety of structures. The
material is typically an expandable adhesive material and also
typically includes one or more of the following components: a
polymeric admixture; an epoxy resin; a filler; a blowing agent; a
curing agent; an accelerator for the blowing agent or the curing
agent; a tackifier; a coagent; an anti-oxidant; combinations
thereof or the like. Preferably, the polymeric admixture includes
an acrylate, an acetate or both, although not required. One
preferred reinforcement material is a pulped form of aramid fiber,
which can assist in flow control, sag resistance and/or
self-support ability of the material.
[0005] The material may be formed according to a variety of
protocols. In one preferred method, the various components of the
material are intermixed in one or more continuous or batch-type
mixing processes or a combination thereof. The material may be
applied (e.g., adhered) to a variety of structures, which may be
formed of a variety of materials such as aluminum, magnesium,
steel, sheet molding compound, bulk molding compound,
thermoplastics, combinations thereof or the like. Moreover the
material may be employed in a variety of applications such as
baffling, sealing, reinforcement of the like.
DETAILED DESCRIPTION OF THE INVENTION
[0006] The present invention is predicated upon providing an
improved expandable material, and articles incorporating the same.
The expandable material preferably expands upon activation by heat
or other condition. Preferably, although not required, the
expandable material can exhibit relatively high levels of expansion
while maintaining homogeneity of expansion and/or without
experiencing cohesive failure. Additionally, it has been found that
the expandable material is particularly useful in applications such
as providing sound absorption, baffling or sealing to articles of
manufacture such as automotive vehicles.
[0007] In a typical application, the expandable material can assist
in providing, baffling, adhesion, sealing, acoustical damping
properties, reinforcement or a combination thereof within a cavity
of or upon a surface of a structure, or to one or more members
(e.g., a body panel or structural member) of an article of
manufacture (e.g., an automotive vehicle).
[0008] The expandable material preferably includes a combination of
three or more of the following components: [0009] (a) up to about
85 parts by weight of a polymeric material admixture such as an
admixture of acrylates, acetates or the like; [0010] (b) up to
about 20 parts by weight epoxy resin; [0011] (c) up to about 20
parts by weight of a tackifier such as a hydrocarbon resin; [0012]
(d) up to about 25 parts by weight blowing agent; [0013] (e) up to
about 10 parts by weight curing agent; and [0014] (f) up to about
40 parts by weight filler.
[0015] The expandable material of the present invention may be
applied to various articles of manufacture for providing acoustical
damping to the articles, for sealing the articles or for providing
reinforcement to the articles. Examples of such articles of
manufacture include, without limitation, household or industrial
appliances, furniture, storage containers, buildings, structures or
the like. In preferred embodiments, the expandable material is
applied to portions of an automotive vehicle such as body or frame
members (e.g., a vehicle frame rail) of the automotive vehicle. One
method of the present invention contemplates applying the
expandable material to a surface of one of the above structures in
an unexpanded or partially expanded state and activating the
material for expanding it to a volume greater than its volume in
the unexpanded state (e.g., 1000% greater, 2000% greater, 2500%
greater, 3000% greater, 3500% greater or higher).
[0016] Percentages herein refer to weight percent, unless otherwise
indicated.
[0017] Polymeric Material Admixture The expandable material
typically include polymeric material admixture, which may include a
variety of different polymers, such as thermoplastics, elastomers,
plastomers combinations thereof or the like. For example, and
without limitation, polymers that might be appropriately
incorporated into the polymeric admixture include halogenated
polymers, polycarbonates, polyketones, urethanes, polyesters,
silanes, sulfones, allyls, olefins, styrenes, acrylates,
methacrylates, epoxies, silicones, phenolics, rubbers,
polyphenylene oxides, terphthalates, acetates (e.g., EVA),
acrylates, methacrylates (e.g., ethylene methyl acrylate polymer)
or mixtures thereof. Other potential polymeric materials may be or
may include, without limitation, polyolefin (e.g., polyethylene,
polypropylene) polystyrene, polyacrylate, poly(ethylene oxide),
poly(ethyleneimine), polyester, polyurethane, polysiloxane,
polyether, polyphosphazine, polyamide, polyimide, polyisobutylene,
polyacrylonitrile, poly(vinyl chloride), poly(methyl methacrylate),
poly(vinyl acetate), poly(vinylidene chloride),
polytetrafluoroethylene, polyisoprene, polyacrylamide, polyacrylic
acid, polymethacrylate.
[0018] The polymeric admixture typically comprises a substantial
portion of the expandable material (e.g., up to 85% by weight or
greater). Preferably, the polymeric admixture comprises about 25%
to about 85%, more preferably about 40% to about 75% and even more
preferably about 50% to about 70% by weight of the expandable
material.
[0019] Although not required, it is preferable for the polymeric
admixture to include one or more acrylates. The acrylates may
include, for example, simple acrylate, methyl acrylate, ethyl
acrylate, butyl acrylate, vinyl acrylate, copolymers or
combinations thereof or the like. Moreover, any of these acrylates
may include other chemical groups such as epoxy, ethylene,
butylene, pentene or the like for forming compounds such as
ethylene acrylate, ethylene methyl acrylate and so on, and
additionally for forming copolymers or combinations thereof or the
like. When included, the one or more acrylates typically comprise
about 20% or less to about 95% or greater, more preferably about
40% to about 85% and even more preferably about 55% to about 75% by
weight of the polymeric admixture.
[0020] A preferred acrylate is a copolymer of butyl acrylate and
methyl acrylate and more particularly a copolymer of an ethylene
butyl acrylate and ethylene methyl acrylate. An example of such a
copolymer is sold under the tradename LOTRYL 35BA40 and is
commercially available from ATOFINA Chemical, Inc., 2000 Market
Street, Philadelphia, PA 19103. Another preferred acrylate is an
epoxy modified (e.g., epoxidized) acrylate copolymer. An example of
such a copolymer is sold under the tradename ELVALOY 4170 and is
commercially available from E. I. Dupont De Nemours and Company,
1007 Market Street, Wilmington, Del. 19898.
[0021] It is also preferable, although again, not required, that
the polymeric admixture include one or more acetates. The acetates
may include, for example, acetate, methyl acetate, ethyl acetate,
butyl acetate, vinyl acetate, copolymers or combinations thereof or
the like. Moreover, any of these acetates may include other
chemical groups such as epoxy, ethylene, butylene, pentene or the
like for forming compounds such as ethylene acrylate, ethylene
methyl acrylate and so on and additionally for forming copolymers
or combinations thereof or the like. When included, the one or more
acetates typically comprise about 5% or less to about 50% or
greater, more preferably about 7% to about 35% and even more
preferably about 15% to about 25% by weight of the polymeric
admixture.
[0022] A preferred acetate is ethylene vinyl acetate (EVA). One
example of such an acetate is a relatively high ethylene content
EVA sold under the tradename ESCORENE UL-7760, commercially
available from ExxonMobil Chemical, 13501 Katy Freeway, Houston,
Tex. 77079-1398. Another example of such an acetate is a relatively
low molecular weight/low melt index EVA sold under the tradename
ESCORENE UL-MV02514, commercially available from Exxon Mobile
Chemical, 13501 Katy Freeway, Houston, Tex. 77079-1398.
[0023] Epoxy Resin
[0024] Epoxy resin is used herein to mean any of the conventional
dimeric, oligomeric or polymeric epoxy materials containing at
least one epoxy functional group. The polymer-based materials may
be epoxy containing materials having one or more oxirane rings
polymerizable by a ring opening reaction. In preferred embodiments,
the expandable material includes up to about 20% of an epoxy resin.
More preferably, the expandable includes between about 0.1% and 10%
by weight epoxy resin.
[0025] The epoxy may be aliphatic, cycloaliphatic, aromatic or the
like. The epoxy may be supplied as a solid (e.g., as pellets,
chunks, pieces or the like) or a liquid (e.g., an epoxy resin). The
epoxy may include an ethylene copolymer or terpolymer that may
possess an alpha-olefin. As a copolymer or terpolymer, the polymer
is composed of two or three different monomers, i.e., small
molecules with high chemical reactivity that are capable of linking
up with similar molecules.
[0026] Preferably, an epoxy resin is added to the expandable
material to increase properties such as adhesion, cohesion or the
like of the material. Additionally, the epoxy resin may strengthen
cell structure when the expandable material is a foamable material.
One exemplary epoxy resin may be a phenolic resin, which may be a
novalac type or other type resin. Other preferred epoxy containing
materials may include a bisphenol-A epichlorohydrin ether polymer,
or a bisphenol-A epoxy resin which may be modified with butadiene
or another polymeric additive.
[0027] Tackifier
[0028] A variety of tackifiers or tackifying agents may be included
in the expandable material. Exemplary tackifiers include, without
limitation, resins, phenolic resins (e.g., thermoplastic phenolic
resins), aromatic resins, synthetic rubbers, alcohols or the like.
According to one preferred embodiment, a hydrocarbon resin 9 (e.g.,
a C5 resin, a C9 resin, a combination thereof or the like) is
employed as a tackifier. The hydrocarbon resin may be saturated,
unsaturated or partially unsaturated (i.e., have 1, 2, 3 or more
degrees of unsaturation). One example of a preferred hydrocarbon
resin is a coumarone-indene resin. Another example of a preferred
hydrocarbon resin is sold under the tradename NORSELENE.RTM. S-105
and is commercially available from Sartomer Company, Inc., 502
Thomas Jones Way, Exton, Pa. 19341.
[0029] When used, the tackifer preferably comprises about 0.1% or
less to about 30% or greater, more preferably about 2% to about 25%
and even more preferably about 6% to about 20% by weight of the
expandable material. Advantageously, the tackifier may be able to
assist in controlling cure rates for producing a more consistent or
predictable expansion for the expandable material.
[0030] Blowing Agent
[0031] One or more blowing agents may be added to the expandable
material for producing inert gasses that form, as desired, an open
and/or closed cellular structure within the expandable material. In
this manner, it may be possible to lower the density of articles
fabricated from the material. In addition, the material expansion
helps to improve sealing capability, substrate wetting ability,
adhesion to a substrate, acoustic damping, combinations thereof or
the like.
[0032] The blowing agent may include one or more nitrogen
containing groups such as amides, amines and the like. Examples of
suitable blowing agents include azodicarbonamide,
dinitrosopentamethylenetetramine,
4,4.sub.i-oxy-bis-(benzenesulphonylhydrazide), trihydrazinotriazine
and N, N.sub.i-dimethyl-N,N.sub.i-dinitrosoterephthalamide.
[0033] An accelerator for the blowing agents may also be provided
in the expandable material. Various accelerators may be used to
increase the rate at which the blowing agents form inert gasses.
One preferred blowing agent accelerator is a metal salt, or is an
oxide, e.g. a metal oxide, such as zinc oxide. Other preferred
accelerators include modified and unmodified thiazoles or
imidazoles, ureas or the like.
[0034] Amounts of blowing agents and blowing agent accelerators can
vary widely within the expandable material depending upon the type
of cellular structure desired, the desired amount of expansion of
the expandable material, the desired rate of expansion and the
like. Exemplary ranges for the amounts of blowing agents, blowing
agent accelerators or both together in the expandable material
range from about 0.1% by weight to about 25%, more preferably about
2% to about 20% and even more preferably about 7% to about 15% by
weight of the expandable material.
[0035] In one embodiment, the present invention contemplates the
omission of a blowing agent. Thus it is possible that the material
will not be an expandable material. Preferably, the formulation of
the present invention is thermally activated. However, other agents
may be employed for realizing activation by other means, such as
moisture, radiation, or otherwise.
[0036] Curing Agent
[0037] One or more curing agents and/or curing agent accelerators
may be added to the expandable material. Amounts of curing agents
and curing agent accelerators can, like the blowing agents, vary
widely within the expandable material depending upon the type of
cellular structure desired, the desired amount of expansion of the
expandable material, the desired rate of expansion, the desired
structural properties of the expandable material and the like.
Exemplary ranges for effective amounts of the curing agents, curing
agent accelerators of both together present in the expandable
material range from about 0% by weight to about 7% by weight.
[0038] Preferably, the curing agents assist the expandable material
in curing by crosslinking of the polymers, epoxy resins (e.g., by
reacting in stoichiometrically excess amounts of curing agent with
the epoxide groups on the resins) or both. It is also preferable
for the curing agents to assist in thermosetting the expandable
material. Useful classes of curing agents are materials selected
from aliphatic or aromatic amines or their respective adducts,
amidoamines, polyamides, cycloaliphatic amines, (e.g., anhydrides,
polycarboxylic polyesters, isocyanates, phenol-based resins (such
as phenol or cresol novolak resins, copolymers such as those of
phenol terpene, polyvinyl phenol, or bisphenol-A formaldehyde
copolymers, bishydroxyphenyl alkanes or the like), peroxides or
mixtures thereof. Particular preferred curing agents include
modified and unmodified polyamines or polyamides such as
triethylenetetramine, diethylenetriamine tetraethyltenepentamine,
cyanoguanidine, dicyandiamides and the like. An accelerator for the
curing agents (e.g., a modified or unmodified urea such as
methylene diphenyl bis urea, an imidazole or a combination thereof)
may also be provided for preparing the expandable material.
[0039] Though longer curing times are also possible, curing times
of less than 5 minutes, and even less than 30 seconds are possible
for the formulation of the present invention. Moreover, such curing
times can depend upon whether additional energy (e.g., heat, light,
radiation) is applied to the material or whether the material is
cured at room temperature.
[0040] Filler
[0041] The expandable material may also include one or more
fillers, including but not limited to particulated materials (e.g.,
powder), beads, microspheres, nanoparticles or the like. Preferably
the filler includes a relatively low-density material that is
generally non-reactive with the other components present in the
expandable material.
[0042] Examples of fillers include silica, diatomaceous earth,
glass, clay, talc, pigments, colorants, glass beads or bubbles,
glass, carbon ceramic fibers, antioxidants, and the like. Such
fillers, particularly clays, can assist the expandable material in
leveling itself during flow of the material. The clays that may be
used as fillers may include nanoparticles of clay and/or clays from
the kaolinite, illite, chloritem, smecitite or sepiolite groups,
which may be calcined. Examples of suitable fillers include,
without limitation, talc, vermiculite, pyrophyllite, sauconite,
saponite, nontronite, montmorillonite or mixtures thereof. The
clays may also include minor amounts of other ingredients such as
carbonates, feldspars, micas and quartz. The fillers may also
include ammonium chlorides such as dimethyl ammonium chloride and
dimethyl benzyl ammonium chloride. Titanium dioxide might also be
employed.
[0043] In one preferred embodiment, one or more mineral or stone
type fillers such as calcium carbonate, sodium carbonate or the
like may be used as fillers. In another preferred embodiment,
silicate minerals such as mica may be used as fillers. It has been
found that, in addition to performing the normal functions of a
filler, silicate minerals and mica in particular improved the
impact resistance of the cured expandable material.
[0044] When employed, the fillers in the expandable material can
range from 1% to 90% by weight of the expandable material.
According to some embodiments, the expandable material may include
from about 3% to about 30% by weight, and more preferably about 10%
to about 20% by weight clays or similar fillers.
[0045] It is contemplated that one of the fillers or other
components of the material may be thixotropic for assisting in
controlling flow of the material as well as properties such as
tensile, compressive or shear strength.
[0046] Other Additives
[0047] Other additives, agents or performance modifiers may also be
included in the expandable material as desired, including but not
limited to a UV resistant agent, a flame retardant, an impact
modifier, a heat stabilizer, a UV photoinitiator, a colorant, a
processing aid, an anti-oxidant, a lubricant, a coagent, a
reinforcement (e.g., chopped or continuous glass, glass fiber,
ceramics and ceramic fibers, aramid fibers, aramid pulp, carbon
fiber, acrylate fiber, polyamide fiber, polypropylene fibers,
combinations thereof or the like). In one preferred embodiment, for
example, an acrylate coagent may be employed for enhancing cure
density. It is also contemplated that the expandable material may
include about 0.10 to about 5.00 weight percent of an anti-oxidant
such as a propionate (e.g., pentaerythritol tetrakis
(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate)) for assisting
in controlling oxidation, cure rate or both. An example of such an
anti-oxidant is sold under the tradename IRGANOX.RTM. 1010 and is
commercially available from Ciba Specialty Chemicals Company, 141
Klybeckstrasse, Posffach, 4002 Basel, Switzerland.
[0048] When determining appropriate components for the expandable
material, it may be important to form the material such that it
will only activate (e.g., flow, foam or otherwise change states) at
appropriate times or temperatures. 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 environment. More typically, the expandable material
becomes activated to flow at higher processing temperatures. As an
example, temperatures such as those encountered in an automobile
assembly plant may be appropriate, especially when the expandable
material is processed along with the other components at elevated
temperatures or at higher applied energy levels, e.g., during
painting preparation steps. Temperatures encountered in many
coating operations (e.g., in a paint curing oven), for instance,
range up to about 180.degree. C. or higher, 200.degree. C. or
higher, 250.degree. C. or higher.
[0049] For mixing the additives, fillers or both, it may be
preferable for the additives or fillers to be mixed with a
dispersant prior to mixing them with the other ingredients of the
expandable material. Such a dispersant will typically have a
relatively low molecular weight of less than about 100,000 amu,
more preferably less than about 50,000 amu and still more
preferably less than about 10,000 amu, although not required.
Examples of such dispersants include, without limitation, liquid
waxes, liquid elastomers or the like such as ethylene-propylene
rubber (EPDM), paraffins (e.g., paraffin wax).
[0050] When the material is expandable, it is possible to make a
family of materials according to the present invention wherein the
members of the family have different expansion levels. Such a
family is, at least in part, may be formed by varying the amount of
blowing agent, blowing agent accelerator or both. For exemplary
purposes, table A is provided below for showing amounts of blowing
agents and/or blowing agent accelerators for one particular family
that may be formed according to the present invention along with
exemplary levels of expansion for materials in the family.
TABLE-US-00001 TABLE A Weight Percent of Percent Volume of Blowing
Agent, Blowing Expanded Material as Compared Agent Accelerator or
Both to Non-Expanded Material Up to 1.5% or 2.0% or greater Up to
About 300% to about 400% or greater Up to 3.0% or 3.5% or greater
Up to About 700% to about 800% or greater Up to 5.0% or 5.5% or
greater Up to About 1150% to about 1250% or greater Up to 7.0% or
8% or greater Up to About 1550% to about 1750% or greater Up to
9.0% or 10% or greater Up to About 2100% to about 2250% or greater
Up to 13% or 14% or greater Up to About 2900% to about 3000% or
greater
[0051] For balancing out the formulation, it may be desirable for a
filler (e.g., a mineral filler) to replace the weight percent of
blowing agent or blowing agent accelerator that is removed for
materials having lower expansion. As an example, if 5 weight
percent of the material is removed by removing blowing agent or
accelerator, it may be desirable to replace the 5 weight percent
with filler.
[0052] Highly Preferred Embodiments and Examples
[0053] It is contemplated within the present invention that
polymers or other materials other than those discussed above may
also be incorporated into the expandable material, e.g., by
copolymerization, by blending, or otherwise. Below, exemplary
formulations of the expandable material are provided. Since they
are merely exemplary, it is contemplated that the weight percents
of the various ingredients may vary by .+-.75% or more or by
.+-.50% or .+-.30%. Moreover, ingredients may be added or removed
from the formulations.
EXAMPLE
[0054] Table B shows a formulation for one exemplary expandable
material. TABLE-US-00002 TABLE B Ingredient name: % by weight
Copolymer of Ethylene Butyl Acrylate and 34.20 Ethylene Methyl
Acrylate High Ethylene content Ethylene Vinyl Acetate 15.00 Epoxy
Modified Acrylate Copolymer 6.00 Low Molecular Weight Ethylene
Vinyl Acetate 6.00 Epoxy resin 1.00 A tackifier resin or agent
(e.g., a hydrocarbon 11.70 resin, a rosin ester, a terpentine)
Acrylate coagent for cure density control (e.g., 0.60
dipentaerythritol pentaacrylate) Curing agent (e.g., peroxide based
curing 1.50 agent) Curing agent - 60.degree. C.-100.degree. C.
activation 0.20 Americure curing agent 0.10 Blowing agent
accelerator (e.g., Zinc Oxide) 1.50 Blowing agent (e.g.,
azodicarbonamide) 9.00 Around 30% Aramid pulp + around 70% EPDM 1.0
Pigment 0.2 Calcium carbonate 11.5 Anti-oxidant 0.5
[0055] Formation and Application of the Expandable Material
[0056] Formation of the expandable material can be accomplished
according to a variety of new or known techniques. Preferably, the
expandable material is formed as a material of substantially
homogeneous composition. However, it is contemplated that various
combining techniques may be used to increase or decrease the
concentration of certain components in certain locations of the
expandable material.
[0057] According to one embodiment, the expandable material is
formed by supplying the components of the material in solid form
such as pellets, chunks and the like, in liquid form or a
combination thereof. The components are typically combined in one
or more containers such as large bins or other containers.
Preferably, the containers can be used to intermix the components
by rotating or otherwise moving the container. Thereafter, heat,
pressure or a combination thereof may be applied to soften or
liquidize the components such that the components can be intermixed
by stirring or otherwise into a single homogenous composition.
[0058] According to another embodiment, the expandable material may
be formed by heating one or more of the components that is
generally easier to soften or liquidize such as the polymer based
materials to induce those components into a mixable state.
Thereafter, the remaining components may then be intermixed with
the softened components. It should be understood that the various
ingredients of the expandable material may be combined in any
desired order. Moreover, the component of the polymeric admixture
may be mixed together and then added to the other ingredients or
may be combined with the other ingredients in any other order.
[0059] Depending upon the components used, it may be important to
assure that the temperature of the components remains below certain
activation temperatures that might cause the expandable material to
activate (e.g., form gasses, flow or otherwise activate), cure
(e.g., harden, stiffen or otherwise change states) or both.
Notably, when the expandable material contains a blowing agent, it
is typically desirable to maintain the temperature of the
expandable material below a temperature that will activate the
blowing agent during formation of the expandable material or before
the expandable material is applied to a surface.
[0060] In situations where it is desirable to maintain the
expandable material at lower temperatures it may be desirable to
maintain the components in a semi-solid or viscoelastic state using
pressure or a combination of pressure and heat to intermix the
components of the expandable material. Various machines have been
designed to applying heat, pressure or both to materials. One
preferred machine is an extruder. According to one embodiment of
the present invention, various components may be premixed into one,
two or more pre-mixtures and introduced at one or various locations
in a single or twin-screw extruder. Thereafter, the heat and
pressure provided by the extruder mixes the expandable material in
a single generally homogeneous composition, and preferably does so
without activating the material.
[0061] Activation of the material may include at least some degree
of foaming or bubbling in situations where the expandable material
includes a blowing agent. Such foaming or bubbling can assist the
expandable material in wetting a substrate and forming an intimate
bond with the substrate. Alternatively, however, it shall be
recognized that the expandable material may be activated to flow
without foaming or bubbling and may still substantially wet the
substrate to form an intimate bond. Formation of the intimate bond
will typically but not necessarily occur upon curing of the
expandable material. In one embodiment, a robotic extrusion
applicator is employed, e.g., of the type disclosed in U.S. Pat.
No. 5,358,397, hereby incorporated by reference.
[0062] Other applications for which the present technology may be
adapted or employed as an expandable material include those of the
type identified in U.S. Pat. Nos. 6,358,584; 6,311,452; 6,296,298,
all of which are hereby incorporated by reference. The material of
the present invention may thus be applied to a carrier, such as a
molded, extruded or stamped member (e.g., metal or plastic, foamed
or unfoamed; exemplary materials of which include aluminum,
magnesium, titanium, steel, polyamide (e.g., nylon 6 or nylon 6,6),
polysulfone, thermoplastic imide, polyether imide, polyether
sulfone or mixtures thereof. Other examples of preferred
applications are disclosed and discussed in commonly owned patent
application titled "Fastenable Member for Sealing, Baffling, or
Reinforcing and Method of Forming Same", Attorney Docket No.
1001-142P1 filed on the same date herewith.
[0063] Advantageously, certain embodiments of the present invention
have exhibited relatively high levels of expansion coupled with
homogeneity and/or cohesiveness during such expansion. Thus, upon
expansion, the expandable material can fill relatively large open
spaces (e.g., cavities) while exhibiting improved properties for
sealing, baffling, sound absorption or the like.
[0064] The preferred embodiment of the present invention has been
disclosed. A person of ordinary skill in the art would realize
however, that certain modifications would come within the teachings
of this invention. Therefore, the following claims should be
studied to determine the true scope and content of the
invention.
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