U.S. patent application number 13/713164 was filed with the patent office on 2013-04-25 for chemical vapor resistant epoxy composition.
This patent application is currently assigned to Henkel Corporation. The applicant listed for this patent is Henkel Corporation. Invention is credited to Boris Krivopal, Robert Pauze, Timothy P. Walsh.
Application Number | 20130098676 13/713164 |
Document ID | / |
Family ID | 45874303 |
Filed Date | 2013-04-25 |
United States Patent
Application |
20130098676 |
Kind Code |
A1 |
Pauze; Robert ; et
al. |
April 25, 2013 |
CHEMICAL VAPOR RESISTANT EPOXY COMPOSITION
Abstract
A two part, curable, epoxy composition useful for potting or
sealing electrical devices for use in hazardous locations. Cured
reaction products of the epoxy composition meet most or all UL 674
requirements and are useful to seal apertures in electrical
equipment. Equipment sealed with the disclosed compositions can
meet the UL 674 requirement.
Inventors: |
Pauze; Robert; (Middleboro,
MA) ; Krivopal; Boris; (Brighton, MA) ; Walsh;
Timothy P.; (Weymouth, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Henkel Corporation; |
Rocky Hill |
CT |
US |
|
|
Assignee: |
Henkel Corporation
Rocky Hill
CT
|
Family ID: |
45874303 |
Appl. No.: |
13/713164 |
Filed: |
December 13, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/US2011/052121 |
Sep 19, 2011 |
|
|
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13713164 |
|
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61385692 |
Sep 23, 2010 |
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Current U.S.
Class: |
174/520 ; 427/58;
523/400; 523/427 |
Current CPC
Class: |
H05K 5/069 20130101;
H05K 5/02 20130101; C09D 163/04 20130101; C08G 59/184 20130101;
C09D 5/00 20130101; C08K 5/17 20130101; C09J 163/00 20130101; C08K
5/17 20130101; C08L 63/00 20130101 |
Class at
Publication: |
174/520 ;
523/427; 523/400; 427/58 |
International
Class: |
C09D 163/04 20060101
C09D163/04; H05K 5/02 20060101 H05K005/02 |
Claims
1. A two part, epoxy composition suitable for sealing equipment for
use in Division 1 hazardous locations, comprising two reactive
components: an epoxy resin component comprising a novolac epoxy
resin, a bisphenol F epoxy resin or a mixture thereof; and a curing
agent component separated from the epoxy resin component,
comprising an adduct of an amine and an epoxy resin.
2. The two part epoxy composition of claim 1 wherein the epoxy
resin component consists essentially of a novolac epoxy resin, a
bisphenol F epoxy resin or a mixture thereof.
3. The two part epoxy composition of claim 1 wherein a mixture of 2
parts by volume epoxy resin component to 1 part by volume curing
agent component has an initial viscosity of about 8,000 to about
30,000 cps.
4. The two part epoxy composition of claim 1 wherein a mixture of 2
parts by volume epoxy resin component to 1 part by volume curing
agent component has an initial viscosity of about 15,000 cps.
5. The two part epoxy composition of claim 1 which does not include
a bisphenol A epoxy resin.
6. The two part epoxy composition of claim 1 wherein the curing
agent component does not include an adduct of an amine and a
bisphenol A epoxy resin.
7. The two part epoxy composition of claim 1 wherein the curing
agent component does not include an adduct of an amine and a
bisphenol A epoxy resin.
8. The two part epoxy composition of claim 1 wherein a cured
reaction product of a mixture of 2 parts by volume epoxy resin
component to 1 part by volume curing agent component meets the
requirements of UL 674, section 45.
9. The two part, epoxy composition of claim 1, further comprising
at least one of 2-furanmethanol and benzyl alcohol.
10. The two part epoxy composition of claim 1 having a maximum
exotherm temperature of 150.degree. C. when tested by Differential
Scanning calorimetry.
11. The two part epoxy composition of claim 1 wherein a mixture of
2 parts by volume epoxy resin component to 1 part by volume curing
agent component will self level.
12. Cured reaction products of the two part, epoxy composition of
claim 1.
13. An electrical device, comprising: a housing defining an
aperture providing a route between a housing exterior and a housing
interior volume; and cured reaction products of the two part, epoxy
composition of claim 1 sealing the aperture, wherein the electrical
device is suitable for use in Division 1 hazardous locations.
14. The electrical device of claim 13, comprising a wire disposed
through the aperture and the cured reaction products.
15. The electrical device of claim 13, wherein the electrical
device is compliant with UL 674.
16. A method of using an epoxy composition to seal an electrical
device, comprising providing an electrical device having a housing
enclosing an interior space and having an exterior surface, the
exterior surface defining an aperture providing communication into
and out of the interior space; disposing the epoxy composition of
claim 1 into the housing aperture; exposing the epoxy composition
to conditions appropriate to cure the epoxy composition to form
cured reaction products in the housing aperture; wherein the cured
reaction products seal the housing interior space and the
electrical device is suitable for use in Division 1 hazardous
locations.
17. The method of claim 16, comprising a wire disposed through the
aperture and the cured reaction products.
18. The method of claim 16, wherein the electrical device is
compliant with UL 674.
Description
FIELD
[0001] The present disclosure relates generally to a two part,
curable, epoxy composition useful for potting or sealing electrical
devices for use in hazardous locations.
BACKGROUND
[0002] Some applications require the use of electrical equipment in
hazardous locations where exposure to chemical, flammable and/or
combustible conditions is likely. Electrical equipment used in such
hazardous locations requires construction to, and compliance with,
exacting standards to lessen the chance of electrical equipment
malfunction and failure.
[0003] Underwriters Laboratories Inc. (UL) is an independent
product safety certification organization that has been testing
products and writing safety standards for over a century.
Underwriters Laboratories, Inc has written safety standard UL 674
"Standard for Electric Motors and Generators for Use in Division 1
Hazardous (Classified) Locations". Electrical equipment such as
motors, generators, panels, raceways and junctions used under
hazardous conditions can be constructed in accordance to the UL 674
standard. Equipment used in such conditions typically must be
approved under this standard. Approval under a UL standard can
require testing of the system and/or system components to ensure
compliance with that UL standard.
[0004] One part of the UL 674 standard requires that openings in
electrical equipment be potted or sealed with an approved material
that can meet specific performance criteria for resistance to
chemicals. These criteria are specified in UL standard 674, section
45. UL standard 1203, "Tests On Sealing Materials", is similar to
UL 674, section 45. This standard specifies resistance to damage
and degradation of a sealant material after exposure to vapors from
a number of specified chemicals. Approved sealant materials must
retain at least 85% of their compressive strength after 168 hours
exposure to saturated vapors in air of each of the specified
chemicals and must not shrink, swell, crack or lose or gain more
than 1 percent of their weight.
[0005] Most epoxy compositions will degrade substantially when
exposed to one or more of the test chemical vapors and therefore
can not meet the chemical resistance requirements of UL 674.
Retention of at least 85% compression strength after exposure to
glacial acetic acid is especially difficult for most epoxy
compositions.
[0006] There are very few materials alleged to be approved for use
under the UL 674 standard. One material is CHICO available from
Crouse Hinds Cooper. CHICO is an inorganic cementitious material
that is mixed with water and poured into a fitting or aperture to
form a seal. More recently, CHICO SPEEDSEAL available from Crouse
Hinds Cooper has been approved. CHICO SPEEDSEAL is believed to be
polyurethane that expands during curing to form a seal in a fitting
or aperture. Other useful sealants are KNEADASEAL and KNEADASEAL SL
available from Polymeric Systems, Inc. of Pennsylvania, USA.
KNEADASEAL is a solid epoxy putty stick that is kneaded between a
user's fingers to mix and subsequently forced into a fitting or
aperture to form a seal that subsequently cures. Forcing the dense,
solid putty into a small aperture to form a seal is difficult,
especially if wires penetrate the aperture. KNEADASEAL SL is a
pourable epoxy compound. Technical literature notes that KNEADASEAL
SL contains bisphenol A epoxy resins.
SUMMARY
[0007] Briefly, one aspect of the disclosure provides a two part
epoxy composition comprising an epoxy resin component and a curing
agent component. The epoxy resin component advantageously comprises
a novolac resin, a diglycidyl ether of bisphenol F resin or a
combination thereof. The curing agent component advantageously
comprises an amine, an amine functional adduct of an amine and an
epoxy resin, or a combination thereof. In an advantageous variation
the curing agent component comprises an aliphatic or cycloaliphatic
amine, an amine functional adduct of ethylene diamine and an epoxy
resin, or a combination thereof. The epoxy composition can
optionally include one or more composition additives in the epoxy
resin component or the curing agent component.
[0008] In one embodiment the epoxy resin component consists
essentially of a novolac resin, a diglycidyl ether of bisphenol F
resin or a combination thereof. As used herein an epoxy component
that consists essentially of a novolac resin, a diglycidyl ether of
bisphenol F resin or a combination thereof does not include epoxy
resins other than a novolac resin or a diglycidyl ether of
bisphenol F resin but may include other non-epoxy resin
components.
[0009] In one embodiment the curing agent component consists
essentially of an aliphatic or cycloaliphatic amine, an amine
functional adduct of bisphenol F, or a combination thereof. As used
herein a curing agent component consists essentially of an
aliphatic or cycloaliphatic amine, an amine functional adduct of
bisphenol F or a combination thereof does not include curatives
other than curing agent component consists essentially of an
aliphatic or cycloaliphatic amine, an amine functional adduct of
ethylene diamine and an epoxy resin, or a combination thereof but
may include other non-epoxy curative components.
[0010] The two components are stored separately and mixed in
predefined proportions to form a mixed epoxy composition shortly
before use. Curing of the mixed composition starts when the
components are mixed and proceeds at room temperature.
[0011] The mixed epoxy composition can be disposed within an
electrical housing aperture and will flow around projections in the
aperture. Cured reaction products of the epoxy composition meet
most or all UL 674 requirements and are useful to seal apertures in
electrical equipment. Equipment sealed with the disclosed
compositions can meet the UL 674 requirement.
[0012] The disclosed compounds include any and all isomers and
stereoisomers. In general, unless otherwise explicitly stated the
disclosed materials and processes may be alternately formulated to
comprise, consist of, or consist essentially of, any appropriate
components, moieties or steps herein disclosed. The disclosed
materials and processes may additionally, or alternatively, be
formulated so as to be devoid, or substantially free, of any
components, materials, ingredients, adjuvants, moieties, species
and steps used in the prior art compositions or that are otherwise
not necessary to the achievement of the function and/or objective
of the present disclosure.
[0013] When the word "about" is used herein it is meant that the
amount or condition it modifies can vary some beyond the stated
amount so long as the function and/or objective of the disclosure
are realized. The skilled artisan understands that there is seldom
time to fully explore the extent of any area and expects that the
disclosed result might extend, at least somewhat, beyond one or
more of the disclosed limits. Later, having the benefit of this
disclosure and understanding the concept and embodiments disclosed
herein, a person of ordinary skill can, without inventive effort,
explore beyond the disclosed limits and, when embodiments are found
to be without any unexpected characteristics, those embodiments are
within the meaning of the term about as used herein.
DETAILED DESCRIPTION
[0014] The disclosed epoxy composition is a two part composition
comprising an epoxy resin component and a separate curing agent
component. As used herein a two part composition has two components
that are kept separate until use. Shortly before use the two
components are homogeneously mixed. The mixture can gel, increasing
in viscosity and stiffness, at about room temperature and in a
short time, for example about 20 minutes to about 240 minutes.
During this time the mixture will increase in viscosity and
stiffness to a point at which it is not convenient or even possible
to use. This time is also referred to as working life. The mixture
can subsequently cure, for example, in about 24 hours to about 240
hours to provide substantial physical properties. Because the two
part epoxy composition begins to gel and cure at room temperature
upon mixing of the resin component and the curing agent component,
the mixture will have substantially no storage life beyond the cure
time. Room temperature typically falls within the range of about
20.degree. C. (68.degree. F.) to about 25.degree. C. (77.degree.
F.). The two part epoxy composition does not include a latent
hardener as the main curing component. The two part epoxy
composition does not require heat to initiate a cure reaction,
although heat can be optionally used to accelerate an existing cure
reaction or to "push" an existing cure reaction toward completion.
The two part epoxy composition is distinguished from, and does not
encompass, a single part epoxy composition comprising a storable
mixture of epoxy resin and latent hardener. The single part epoxy
composition is stable, e.g. does not gel or cure, at about room
temperature for long periods of time and requires elevated
temperatures to activate the latent curing agent and thereby
initiate a reaction between the resin part and the hardener. The
latent hardener of a single part composition can not initiate a
reaction useful to cure the single part composition at about room
temperature in a short time to provide substantial physical
properties. One or both of the epoxy resin component and the curing
agent component comprise one or more additives.
[0015] Cured reaction products of the disclosed epoxy composition
can meet most or all of the chemical resistance and other
requirements for sealing compounds set out in UL 674 section 45 and
are useful as sealants and potting compounds for electrical
equipment used under this standard. UL standard 674 and UL standard
1203 are each incorporated by reference herein in their
entirety.
[0016] Typically, the epoxy composition, e.g. the mixture of epoxy
resin component and curing agent component, comprises about 80
weight percent to about 100 weight percent of epoxy resin
component.
Epoxy Resin Component
[0017] Epoxy resins are characterized by one or more of their
precursors, structure, oxirane oxygen content and epoxy equivalent
weight. The epoxy equivalent weight is the weight of resin required
to obtain one equivalent of epoxy functional group. The epoxy
resins can be semisolid epoxy resins, solid epoxy resins, liquid
epoxy resins and mixtures of the above resins.
[0018] In general, a large number of polyepoxides having at least
about two epoxy groups per molecule are available. The polyepoxides
may be saturated, unsaturated, cyclic or acyclic, aliphatic,
alicyclic, aromatic or heterocyclic polyepoxide compounds. Examples
of polyepoxides include the polyglycidyl ethers, which are prepared
by reaction of epichlorohydrin or epibromohydrin with a polyphenol
in the presence of alkali. Other exemplary polyphenols are, for
example, resorcinol, pyrocatechol, hydroquinone, bisphenol A
(bis(4-hydroxyphenyl)-2,2-propane), bisphenol F
(bis(4-hydroxyphenyl)methane), bis(4-hydroxyphenyl)-1,1-isobutane,
4,4'-dihydroxybenzophenone, bis(4-hydroxyphenyl)-1,1-ethane, and
1,5-hydroxynaphthalene. Other polyphenols used as the basis for the
polyglycidyl ethers are the known condensation products of phenol
and formaldehyde or acetaldehyde of the novolac resin-type.
[0019] Other polyepoxides include the polyglycidyl ethers of
polyalcohols or diamines. Such polyglycidyl ethers are derived from
polyalcohols, such as ethylene glycol, diethylene glycol,
triethylene glycol, 1,2-propylene glycol, 1,4-butylene glycol,
triethylene glycol, 1,5-pentanediol, 1,6-hexanediol or
trimethylolpropane.
[0020] Other polyepoxides include polyglycidyl esters of
polycarboxylic acids, for example, reaction products of glycidol or
epichlorohydrin with aliphatic or aromatic polycarboxylic acids,
such as oxalic acid, succinic acid, glutaric acid, terephthalic
acid or a dimeric fatty acid. Other epoxides are derived from the
epoxidation products of olefinically-unsaturated cycloaliphatic
compounds or from natural oils and fats.
[0021] Polyglycidyl ether of bisphenol F resins and novolac resins
are presently believed advantageous for use in this application as
cured reaction products of these resins appear more chemically
resistant than other epoxy resin types such as polyglycidyl ethers
of bisphenol A.
[0022] In one embodiment the epoxy component comprises one or more
novolac epoxy resins, one or more difunctional bisphenol F epoxy
resins or a mixture of one or more novolac epoxy resins and one or
more difunctional bisphenol F epoxy resins. D.E.N. 431 available
from Dow Chemical Company and EPON 154 available from Hexion
Specialty Chemicals are examples of novolac epoxy resins. EPON 863
available from Hexion Specialty Chemicals is an example of a
difunctional bisphenol F epoxy resin.
[0023] In one embodiment the epoxy component comprises a
combination of about 40% to about 99% by weight of epoxy component
of one or more novolac epoxy resins and about 1% to about 60% by
weight of epoxy component of one or more polyglycidyl bisphenol F
epoxy resins.
[0024] In one embodiment the epoxy resin component consists
essentially of a novolac resin, a diglycidyl ether of bisphenol F
resin or a combination thereof. As used herein an epoxy component
that consists essentially of a novolac resin, a difunctional
bisphenol F resin or a combination thereof does not include epoxy
resins other than a novolac resin or a difunctional bisphenol F
resin but may include other non-epoxy resin components such as
composition additives.
[0025] In one embodiment the epoxy component consists essentially
of a combination of about 40% to about 99% by weight of epoxy
component of one or more novolac epoxy resins and about 1% to about
60% by weight of epoxy component of one or more difunctional
bisphenol F epoxy resins.
Curing Agent Component
[0026] The curing agent can comprise hardener compounds that
initiate a cure reaction with the epoxy resin component at about
room temperature. The hardener compound may function in a catalytic
manner or, in advantageous embodiments, participate directly in the
curing process by reaction with the epoxy resin component. Hardener
compounds useful to cure the epoxy resin component at about room
temperature include one or more of aliphatic amines (including
linear aliphatic, branched aliphatic and cycloaliphatic amines),
polyetheramines, polyamides, amidoamines, aromatic amines, and/or
mixtures thereof. Polyamides are condensation products of
polymerized fatty acids with polyalkyl polyamines prepared
according to procedures well know in the art. Specific curing
agents utilized will depend on the specific epoxy resin utilized in
the epoxy resin component, cured product properties desired and to
a lesser extent on the rate and degree of curing desired for the
epoxy composition.
[0027] The curing agent component can include an
aminopolyalkyeneamine component. Some useful aminopolyalkyeneamine
components include, for example, ethylenediamine,
diethylenetriamine, triethylenetetramine, tetraethylenepentamine,
and polymers, oligomers, analogs, such as polyamides like the
Versamid series (Cognis Co), and amidoamines like the Ancamide
series (Air Products), and derivatives thereof, sold by many
manufacturers, and well-known to those skilled in the art.
Aliphatic and cycloaliphatic amines like the Ancamine series (Air
Products) can advantageously be used in the curing agent
component.
[0028] In principle, catalytically active tertiary acryl- or
alkyl-amines, such as benzyldimethylamine,
tris(dimethylamino)phenol, piperidine or piperidine derivatives,
may also be useful. Various imidazole derivatives may also be
useful as catalytically-active accelerators. Examples which may be
mentioned are 2-ethyl-2-methylimidazole, N-butylimidazole,
benzimidazole and N--C.sub.1 to C.sub.12-alkylimidazoles or
N-arylimidazoles.
[0029] In one advantageous variation the curing agent component
comprises an aliphatic or cycloaliphatic amine, an amine functional
adduct of ethylene diamine and an epoxy resin, or a combination
thereof.
[0030] In one advantageous embodiment the curing agent component
comprises a combination of about 15% to about 85% by weight of
curing agent component of an aliphatic amine and about 10% to about
60% by weight of curing agent component of amine functional adduct
of ethylene diamine and an epoxy resin. ANCAMINE 2422 available
from Air Products is an example of a cycloaliphatic amine and
ANCAMINE 2410 is an example of an amine functional adduct of
ethylene diamine and a bisphenol A epoxy resin. It is believed that
a curing agent component comprising an amine functional adduct of a
bisphenol F epoxy resin, when mixed with the epoxy resin component,
would provide cured reaction products of that mixture with improved
chemical resistance and better maintain compressive strength,
dimensional stability and weight stability.
[0031] In one embodiment the curing agent component consists
essentially of a combination of aliphatic amine and an amine
functional adduct of an amine and an epoxy resin. As used herein a
curing agent component consisting essentially of a combination of
aliphatic amine and an amine functional adduct of an amine and an
epoxy resin excludes curing agent components having curing agents
that are not aliphatic amine and an amine functional adduct of an
amine and an epoxy resin.
[0032] The amount of curing agent component utilized in the curable
composition will depend upon a number of factors, including whether
the hardener compound acts as a catalyst or participates directly
in crosslinking of the composition, the concentration of epoxy
groups and other reactive groups in the composition, the desired
curing rate, temperature and so forth. Typically, the epoxy
composition comprises about 1 to 40 weight percent of curing agent
component.
[0033] It may be convenient to use a specific volumetric ratio of
epoxy resin component to curing agent component, for example 1:1,
2:1, 3:1 or 4:1 ratios of epoxy resin component to curing agent
component. Some applications are sensitive to heat and require
sealants having a lower maximum cure temperature, for example about
150.degree. C. and advantageously about 125.degree. C. and
desirably about 100.degree. C. The use of relatively equal ratios,
for example 1 or 2 parts epoxy resin component to 1 part curing
agent component, is desirable for lessening heat evolved by the
mixed composition during the cure reaction and thereby lessening
the maximum cure temperature.
Composition Additives
[0034] The curable composition can optionally include one or more
composition additives. As used herein a composition additive is a
material that is formulated into either or both of the epoxy resin
component or the curing agent component and remains present during
use of the volumetric ratio of epoxy resin to curing agent.
Composition additives include, for example, one or more of types of
cure accelerators, particulate impact modifiers, auxiliary impact
modifiers, auxiliary toughening agents, diluents, adhesion
promoters, fillers, thixotropes, other adjuvants; or combinations
thereof to provide the epoxy resin component, the curing agent
component and/or the mixed epoxy composition with desirable
physical and chemical properties and to provide cured reaction
products of the epoxy composition with desirable physical and
chemical properties. Naturally, the composition additives should
not adversely impact chemical resistance or other properties of the
cured reaction products allowing their use in this application.
Cure Accelerator
[0035] Cure accelerators are materials that materially shorten the
gel time and/or increase completion of cure. Various compounds,
such as tertiary amines, imides, polyamines, cyclicamines and
arylamines also can be included in the epoxy composition as cure
accelerators. Also included as potential accelerators, but not
limited to these, are the following classes: strong acids, organic
and inorganic acids, fluoro acids, fluoro-sulphonic acids, fluoro
acetic acids, water, alcohols, phenols, fluoro-phenols, salicylic
acid, amine, calcium, and metal salts of any or all the acids
above, polyols, active hydrogen materials and their salts and/or
complexes and the like. In one embodiment the epoxy composition
comprises one or more cure accelerators, for example furfuryl
alcohol or benzyl alcohol.
[0036] The useful amounts of accelerator typically range from about
0% by weight to about 30% by weight of the total composition.
Desirably, an accelerator is present in an amount from about 1% by
weight to about 10% by weight of the total composition.
Core-Shell Particulate Impact Modifier
[0037] Toughness of reaction products of the cured epoxy
composition can be improved or modified by the incorporation of one
or more types of particles having a core-shell structure, e.g. a
particle having a core comprised of a first material surrounded by
a shell comprised of a second material, wherein the first and
second materials are typically different. The core-shell particle
can have a core comprised of a polymeric material having
elastomeric or rubbery properties (i.e., a glass transition
temperature less than about 0.degree. C., e.g., advantageously less
than about -30.degree. C.) surrounded by a shell comprised of a
non-elastomeric polymeric material (i.e., a thermoplastic or
thermoset/crosslinked polymer having a glass transition temperature
greater than ambient temperatures, e.g., greater than about
50.degree. C.).
[0038] The core can be formed predominantly from feed stocks of
polybutadiene, polyacrylate, polystyrene, polybutadiene/styrene
mixture, polybutadiene/acrylonitrile mixture, polyols and/or
polysiloxanes or any other monomers that give a lower glass
transition temperature. For example, the core can be comprised of a
diene homopolymer or copolymer (for example, a homopolymer of
butadiene or isoprene; a copolymer of butadiene or isoprene with
one or more ethylenically unsaturated monomers such as vinyl
aromatic monomers, (meth)acrylonitrile, (meth)acrylates, or the
like) or an acrylate or methacrylate polymer. Other rubbery
polymers may also be suitably be used for the core, including
polybutylacrylate elastomer or polysiloxane elastomer (e.g.,
polydimethylsiloxane, particularly crosslinked
polydimethylsiloxane).
[0039] The shell can be formed predominantly from feed stocks of
polymethylmethacrylate, polystyrene or polyvinyl chloride or any
other monomers that give a higher glass transition temperature. For
example, the shell can be comprised of a polymer or copolymer of
one or more monomers such as an acrylate, (meth)acrylate (e.g.,
methyl methacrylate), vinyl aromatic monomer (e.g., styrene), vinyl
cyanide (e.g., acrylonitrile), unsaturated acids and anhydrides
(e.g., acrylic acid), (meth)acrylamide, and the like having a
suitably high glass transition temperature.
[0040] The core-shell particle may be comprised of more than two
layers (e.g., a central core of one material may be surrounded by a
second core of a different material or the core may be surrounded
by two shells of different composition or the particle may have a
soft core, hard shell, soft shell, hard shell structure. The
particles can comprise a core and at least two concentric shells
having different chemical compositions and/or properties. Either
the core or the shell or both the core and the shell may be
crosslinked (e.g., ionically or covalently). The shell may be
grafted onto the core. The polymer comprising the shell may bear
one or more different types of functional groups (e.g., epoxy
groups) that are capable of interacting with other components of
the compositions of the present invention.
[0041] Some of the core-shell particles structures available from
Rohm and Haas are believed to have a core made from cross linked
poly(butadiene/styrene) and a polymethylmethacrylate shell. Some of
the core-shell particles structures available from Nippon Zeon are
believed to have a core comprising an acrylate or methacrylate
polymer having a glass transition of about -30.degree. C. or lower
and a shell comprising an acrylate polymer or a methacrylate
polymer having a glass transition temperature of about 70.degree.
C. or higher.
[0042] The outer surface of the core-shell particle may be modified
by reaction with a coupling agent, oxidizing agent or the like so
as to enhance the ability to disperse the particle in the component
(e.g., reduce agglomeration of the particles, reduce the tendency
of the particles to settle out of the epoxy resin). Modification of
the particle surface may also enhance the adhesion of the epoxy
resin matrix to the particle when the adhesive is cured. The
particle may alternatively be irradiated so as to change the extent
of crosslinking of the polymer(s) constituting the particle in
different regions of the particle. For example, the particle may be
treated with gamma radiation such that the particle material is
more highly crosslinked near the surface of the particle than in
the center of the particle.
[0043] Particles treated with a reactive gas or other reagent to
modify the outer surfaces of the particles by, for instance,
creating polar groups (e.g., hydroxyl groups, carboxylic acid
groups) on the particle surface, are also suitable for use in the
present invention. Illustrative reactive gases include, for
example, ozone, Cl.sub.2, F.sub.2, O.sub.2, SO.sub.3, and oxidative
gases. Methods of surface modifying rubber particles using such
reagents are known in the art and are described, for example, in
U.S. Pat. Nos. 5,382,635; 5,506,283; 5,693,714; and 5,969,053, each
of which is incorporated herein by reference in its entirety.
Suitable surface modified rubber particles are also available from
commercial sources, such as the rubbers sold under the tradename
VISTAMER by Exousia Corporation.
[0044] Typically, the core will comprise from about 50 to about 95
percent by weight of the particle while the shell will comprise
from about 5 to about 50 percent by weight of the particle.
[0045] The particles are relatively small in size. For example, the
average particle size may be from about 30 nm to about 10,000 nm,
advantageously from about 50 nm to about 5,000 nm. In certain
embodiments the rubber particles have an average diameter of less
than about 500 nm. For example, the core-shell particles may have
an average diameter within the range of from about 25 nm to about
400 nm.
[0046] The core shell particles may be dispersed in a matrix, for
example a liquid epoxy matrix. Examples of epoxy matrices include
the diglycidyl ethers of bisphenol A, F or S, or biphenol, novolac
epoxies, cycloaliphatic epoxies and phenolic resins such as
bisphenol-A based phenoxies. Use of polyglycidyl ether of bisphenol
F resins and novolac resins in the epoxy composition are presently
believed advantageous.
[0047] The core shell particles dispersed in a matrix may be
prepared as a masterbatch. For example, the particles are prepared
as aqueous dispersions or emulsions. Such dispersions or emulsions
may be combined with the desired liquid epoxy resin or mixture of
liquid epoxy resins and the water and other volatile substances
removed by distillation or the like to provide the masterbatch.
Dispersions of particles having a core-shell structure in an epoxy
resin matrix are available from Kaneka Corporation under the trade
name KANE ACE MX.
[0048] Where the particles are initially provided in dry form, it
may be advantageous to ensure that such particles are well
dispersed in either or both of the epoxy resin component or the
curing agent component. That is, agglomerates of core-shell
particles are preferably broken up so as to provide discrete
individual particles, which may be accomplished by intimate and
thorough mixing of the dry particles with some or all of the other
components. For example, dry particles may be blended with liquid
epoxy resin for a length of time effective to essentially
completely disperse the core-shell particles therein and break up
any particle agglomerations.
[0049] The core shell particles may be present in the epoxy
composition in an amount in the range of about 1% to about 50% by
weight of the epoxy composition, advantageously about 2% to about
40% by weight of the epoxy composition and desirably about 10% to
about 30% by weight of the epoxy composition. The lower limit will
be based on the increase in toughness desired. At the higher ranges
of core shell particle content, viscosity increases may be observed
in the particle comprising component in relatively short periods of
time. Use of higher amounts of core-shell particles will increase
cost of the epoxy composition and may lower strength of the epoxy
composition cured reaction products without providing a
corresponding increase in toughness. The core shell particles can
be formulated into either or both of the epoxy resin component or
the curing agent component as desirable.
Auxiliary Impact Modifiers/Toughening Agents
[0050] The impact properties of epoxy composition cured reaction
products can be improved or modified by the incorporation of one or
more auxiliary impact modifiers and/or toughening agents. Suitable
auxiliary impact modifier/toughening agents are generally polymeric
or oligomeric in character, have glass transition (Tg) temperatures
below 20.degree. C. (advantageously below 0.degree. C., more
advantageously below -30.degree. C. or below -50.degree. C.), and
may have one or more functional groups capable of participating in
the cure reaction of the epoxy resin component. Suitable reactive
functional groups include epoxy groups, hydroxyl groups, carboxylic
acid groups and the like.
[0051] One type of auxiliary impact modifiers and/or toughening
agent comprises the epoxy-based prepolymers (sometimes described as
"adducts") obtained by reacting one or more epoxy resins with one
or more amine-terminated polymers.
[0052] The epoxy resins useful for preparing epoxy based
prepolymers may be selected from among the epoxy resins described
hereinabove, with particular preference being given to the
diglycidyl ethers of polyphenols such as bisphenol F. Liquid epoxy
resins are preferred although mixtures of solid and liquid epoxy
resins may be employed.
[0053] Amine terminated polymers useful for preparing epoxy-based
prepolymers include, for example, one or more of:
[0054] Amine terminated polyethers such as linear amine-terminated
polyoxyethylene ethers having the formula:
H.sub.2N--(CH.sub.2).sub.2--[O--(CH.sub.2).sub.2--O--(CH.sub.2).sub.2].s-
ub.n--NH.sub.2
in which n preferably is 17 to 27.
[0055] Amine terminated polyethers such as linear amine-terminated
polyoxypropylene ethers having the formula:
##STR00001##
in which n preferably is 5 to 100. They are obtainable from
Huntsman Chemical under the trade name JEFFAMINE.RTM. (D-series).
The number average molecular weight of such amine-terminated
polyoxypropylene ethers may vary, for example, from about 200 to
about 2000.
[0056] Amine terminated polyethers such as trifunctional compounds
having the formula:
##STR00002##
in which A is:
##STR00003##
and x, y and z independently of each other are 1 to 40 and x+y+z is
preferably >6. Representative examples of these trifunctional
compounds are available commercially from Huntsman Chemical under
the tradename JEFFAMINE.RTM. (T-series). Such substances typically
have number average molecular weights of from about 400 to about
5000.
[0057] Amino silane capped polymers, such as those that may be
embraced by the general formula:
##STR00004##
where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 may be the same or
different and are selected from hydrogen, hydroxyl, alkyl, alkoxy,
alkenyl, alkenyloxy, aryl, and aryloxy; R.sup.5 and R.sup.6 may be
the same or different and are selected from hydrogen, alkyl and
aryl; and X is selected from alkylene, alkenylene, arylene, with or
without interruption by a heteroatom; polyurethanes; polyethers;
polyesters; polyacrylates; polyamides; polydienes; polysiloxanes;
and polyimides.
[0058] Amine-terminated siloxanes, such as diamino siloxanes
embraced by the formula:
##STR00005##
where R.sup.11 and R.sup.12 may be the same or different and are
selected from alkylene, arylene, alkylene oxide, arylene oxide,
alkylene esters, arylene esters, alkylene amides or arylene amides;
R.sup.9 and R.sup.10 may be the same or different and are selected
from alkyl or aryl; R.sup.7 and R.sup.8 are as defined above and n
is 1-1,200.
[0059] Certain amino-modified silicone fluids that are commercially
available from Shin-Etsu under the trade designations KF857, KF858,
KF859, KF861, KF864 and KF880 may be useful. In addition, Wacker
Silicones offers commercially a line of amino-functional silicone
fluids designated as L650, L651, L653, L654, L655 and L656, and an
amino-functional polydimethylsiloxane under the tradename WACKER
FINISH WR 1600 that may be useful.
[0060] Other amino-functionalized silanes or siloxanes useful in
forming the adduct include materials available from Degussa's
Sivento division, such as a proprietary aminofunctional silane
composition (DYNASYLAN.RTM. 1126), an oligomeric diaminosilane
system (DYNASYLAN.RTM. 1146),
N-vinylbenzyl-N'-aminoethyl-e-aminopropylpolysiloxane
(DYNASYLAN.RTM. 1175), N-(n-butyl)-3-aminopropyltrimethoxysilane
(DYNASYLAN.RTM. 1189), a proprietary aminofunctional silane
composition (DYNASYLAN.RTM. 1204),
N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane (DYNASYLAN.RTM.
1411), 3-aminopropylmethyldiethoxysilane (DYNASYLAN.RTM. 1505),
3-aminopropylmethyldiethoxysilane (DYNASYLAN.RTM. 1506),
3-aminopropyltriethoxysilane (DYNASYLAN.RTM. AMEO), a proprietary
aminosilane composition (DYNASYLAN.RTM. AMEO-T),
3-aminopropyltrimethoxysilane (DYNASYLAN.RTM. AMMO),
N-2-aminoethyl-3-aminopropyltrimethoxysilane (DYNASYLAN.RTM. DAMO),
N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (DYNASYLAN.RTM.
DAMO-T) and a triamino-functional propyltrimethoxysilane
(DYNASYLAN.RTM. TRIAMO).
[0061] Mixtures of amine-terminated polyethers may be used.
Amine-terminated polyethers containing both oxyethylene and
oxypropylene repeating units may also be utilized as the
amino-terminated polyether. Preferably, the amino-terminated
polyether contains at least two amine groups per molecule.
Preferably, the amine groups are primary amine groups. The
amino-terminated polyether is preferably aliphatic.
[0062] Generally speaking, the ratio of epoxide groups to amine
groups in the adduct will be chosen based on use in the curable
composition. An adduct having an excess of epoxy groups over amino
groups (i.e., the epoxy-based prepolymer contains essentially no
free amine groups) is useful for addition to an epoxy resin
component. Typically, there is a 1.5 to 10-fold excess, for example
a 3.5-fold excess of epoxy groups over the active hydrogen
equivalents (AHEW) of the amine-terminated polyether. An excess of
amino groups over epoxide groups (i.e., the epoxy-based prepolymer
contains no free epoxide groups) is useful for addition to a curing
agent component. Typically, the epoxy-based prepolymer is initially
prepared in a first stage by reacting the epoxy resins with the
amine-terminated polymer in the desired ratio and at an elevated
temperature for a suitable time. The preparation of epoxy-based
prepolymers from amine-terminated polyethers is known in the art
and is described, for example, in U.S. Pat. Nos. 5,084,532 and
6,015,865, each of which is incorporated herein by reference in its
entirety.
[0063] Other tougheners or impact modifiers known in the epoxy
adhesive art may be useful in addition to, or as a substitute for,
the aforementioned epoxy-based prepolymers. Generally speaking,
such tougheners and impact modifiers are characterized by having
glass transition temperatures below about 0.degree. C.,
advantageously below about -30.degree. C. and preferably below
about -50.degree. C. Examples of such tougheners and impact
modifiers include, but are not limited to:
[0064] Reaction products of epoxy-reactive copolymers of conjugated
dienes such as butadiene (especially epoxy-reactive copolymers of
butadiene with relatively polar co-monomers such as
(meth)acrylonitrile, (meth)acrylic acid, or alkyl acrylates, e.g.,
carboxyl-terminated butadiene-nitrile rubbers, such as the products
available commercially from Noveon under the trade name HYCAR) with
epoxy resins (as described, for example, in U.S. Patent Application
Publication No. US 2005/0070634 and U.S. Pat. Nos. 6,776,869 and
6,998,011, each of which is incorporated herein by reference in its
entirety);
[0065] Adducts of anhydrides (e.g., unsaturated anhydrides such as
maleic anhydride) and diene polymers (e.g., liquid 1,4-cis
polybutadienes), typically having number average molecular weights
between about 1000 and about 5000, including for example, the
adducts sold under the tradename POLYVEST by Degussa Corporation,
as well as further reaction products of such adducts with epoxy
resins;
[0066] Polyesters, including, for example, amorphous, crystalline
and/or semi-crystalline polyesters, including saturated polyesters,
prepared by condensation of aliphatic and/or aromatic dicarboxylic
acids (or the corresponding alkyl esters or anhydrides with dials
having a chain length of C.sub.2 to C.sub.20, the polyesters being
of medium molecular weight (e.g., about 1000 to about 20,000 number
average molecular weight), such as the polyesters sold under the
tradename DYNACOLL by Degussa Corporation, and including polyesters
functionalized with carboxylic acid and/or hydroxyl endgroups, as
well as adducts of such functionalized polyesters with epoxy
resins;
[0067] Adducts of dimeric fatty acids with epoxy resins (including,
for example, the adducts sold under the tradename EPON 872 by
Resolution Performance Products, the adducts sold under the
tradename HYPDX DA323 (formerly ERISYS EMDA 3-23) by CVC Specialty
Chemicals, as well as those adducts described in U.S. Pat. No.
5,218,063, incorporated herein by reference in its entirety);
[0068] Adducts of hydroxyl-containing triglycerides (e.g., castor
oil) with epoxy resins (including, for example, the adducts sold
under the tradename HELOXY 505 by Resolution Performance
Products);
[0069] Adducts of polysulfides with epoxy resins (including, for
example, the adducts sold under the tradename THIOPLAST EPS 350 by
Akzo Nobel;
[0070] Adducts of amine-terminated polydienes and diene copolymers
with epoxy resins;
[0071] Polyether prepolymers capped with hydroxyarylcarboxylic or
hydroxyaralkylcarboxylic acids, or a capped polyester,
polythiaester or polyamide containing polyether segments, as
described, for example, in U.S. Pat. No. 5,202,390, incorporated
herein by reference in its entirety, in particular the tougheners
of formula I described in detail at column 1, line 59, to column 2,
line 16, of said patent;
[0072] Block copolymers, wherein at least one polymeric block of
the copolymer has a glass transition temperature below 20.degree.
C. (preferably below 0.degree. C. or below -30.degree. C. or below
-50.degree. C.) and at least one polymeric block of the copolymer
has a glass transition temperature above 20.degree. C. (preferably
above 50.degree. C. or above 70.degree. C.), in particular block
copolymers containing a polystyrene block, a 1,4-polybutadiene
block (preferably having a glass transition temperature below about
-60 degrees C.) and a polymethylmethacrylate block (preferably,
having a highly, i.e., >80%, syndiotactic structure), such as
the SBM copolymers made by living polymerization methods using
nitroxide initiator (such as the methods described in U.S. Pat.
Nos. 5,677,387, 5,686,534, and 5,886,112, each of which is
incorporated herein by reference in its entirety, and sold under
the tradename NANOSTRENGTH by Arkema and the block copolymers
described in U.S. Pat. No. 6,894,113, incorporated herein by
reference in its entirety;
[0073] Carboxyl-functionalized adducts of amino- or
hydroxyl-terminated polymers and carboxylic anhydrides, as well as
further reaction products of such adducts with epoxy resins (such
as those described in U.S. Pat. No. 6,884,854 and U.S. Patent
Application Publication No. 2005/0215730, each of which is
incorporated herein by reference in its entirety);
[0074] Epoxy-terminated polyethers, such as polymers of alkylene
oxides like ethylene oxide, propylene oxide or mixtures thereof
that have been functionalized with epoxy groups, including by
reacting the hydroxy groups of a polyalkylene glycol with
epichlorohydrin;
[0075] Phenol-terminated and aminophenyl-terminated products
produced by reacting a stoichiometric excess of a carboxylic
anhydride or dianhydride with a diamine or polyamine and then
further reacting the excess carboxylic anhydride or carboxylic acid
groups with at least one polyphenol or aminophenol, as described,
for example, in U.S. Patent Application Publication No.
2004/0181013, incorporated herein by reference in its entirety.
[0076] Mixtures of different auxiliary impact modifiers/toughening
agents may be used. The auxiliary impact modifier/toughening agent
may be present in the epoxy composition in an amount in the range
of about 1% to about 50% by weight of the epoxy composition,
advantageously about 5% to about 40% by weight of the epoxy
composition and desirably about 10% to about 30% by weight of the
epoxy composition. Cost and viscosity of the resulting composition
part may dictate the upper limit. The auxiliary impact
modifiers/toughening agents can be formulated into either or both
of the epoxy resin component or the curing agent component as
desirable.
Diluent
[0077] The curable composition can comprise one or more diluents.
The diluent may be reactive or non-reactive. In the reactive sense,
the diluent should possess functionality appropriate to react with
components in the epoxy composition. In the non-reactive sense the
diluent does not react with components and may affect the
flexibility of the cured reaction products and/or be used to
improve the mixability of the epoxy composition components.
Examples of non-reactive diluents include EPODIL LV5 available from
Air Products.
[0078] Reactive diluents can be monofunctional or advantageously
can be polyfunctional. One reactive diluent is monofunctional epoxy
resin. The monofunctional epoxy resin should have an epoxy group
with an alkyl group, examples of which include C.sub.6-C.sub.28
alkyl glycidyl ethers, C.sub.6-C.sub.28 alkyl diglycidyl ethers,
C.sub.6-C.sub.28 fatty acid glycidyl esters and C.sub.6-C.sub.28
alkylphenol glycidyl ethers. Another reactive diluent comprises a
mono-epoxide (e.g., monoglycidyl ethers of alkyl- and
alkenyl-substituted phenols).
[0079] Additional reactive diluents include those having
(meth)acrylate and/or vinyl ether functionality. In some
embodiments that include a reactive diluent, the reactive diluent
is a "hybrid" diluent because it includes at least one vinyl ether
or 1-alkenyl ether group and at least one (meth)acrylate group. For
instance, the reactive diluent may be represented by the following
formula (A):
##STR00006##
where R.sup.1 is selected from hydrogen; aliphatic C.sub.1-6 alkyl;
and C.sub.1-6 cycloalkyl; R.sup.2 is selected from C.sub.2-20
alkylene; C.sub.2-20 hydrocarbon diradical; and polyalkylene oxide;
and R.sup.3 is selected from hydrogen and methyl.
[0080] The reactive diluent may have a molecular weight of less
than about 1500. Advantageously, the molecular weight is less than
about 750, more desirably less than about 500. The viscosity of the
reactive diluent may be less than about 5000 cps at 25.degree. C.,
more desirably less than about 2000 cps and even more desirably
about 50-500 cps.
[0081] The epoxy composition disclosed herein may contain, for
example, up to about 15 weight percent total of diluent. The
diluent can be formulated into either or both of the epoxy resin
component or the curing agent component as desirable.
Adhesion Promoter
[0082] The curable composition can comprise one or more products to
help improve adhesion of reaction products of the cured epoxy
composition to a substrate surface. Useful adhesion promoter
materials include reaction products of epoxy resins and compounds
containing chelating functional groups (herein called
"chelate-modified epoxy resins") and functional silanes.
[0083] Such reaction products include those substances commonly
referred to as "chelate epoxies" or "chelating epoxy resins". The
chelating functional groups include those functional groups capable
of forming chelate bonds with divalent or polyvalent metal atoms,
either by themselves or in cooperation with other functional groups
positioned on the same molecule. Suitable chelating functional
groups include, for example, phosphorus-containing acid groups
(e.g., --PO(OH).sub.2), carboxylic acid groups (--CO.sub.2H),
sulfur-containing acid groups (e.g., --SO.sub.3H), amino groups,
and hydroxyl groups (particularly hydroxyl groups adjacent to each
other on aromatic rings). The preparation of such reaction products
may be carried out by methods known in the art such as, for
example, those methods described in U.S. Pat. Nos. 4,702,962 and
4,340,716, European Patent No. EP 342 035 and Japanese Patent
Document Nos. JP 58-063758 and JP 58-069265, each of which is
incorporated herein by reference in its entirety. Reaction products
of epoxy resins and compounds containing chelating functional
groups are also available from commercial sources such as, for
example, the ADEKA Resins EP-49-10N, EP-49-55C, EP-49-10, EP-49-20,
EP-49-23, and EP-49-25 sold by Asahi Denka.
[0084] Other compounds having metal chelating properties may also
be used to help enhance the adhesion of the cured adhesive to a
substrate surface, including, for example, the adhesion promoters
described in U.S. Patent Application Publication No. U.S.
2005/0129955, incorporated herein by reference in its entirety.
Also suitable for use as adhesion promoters are the
acetoacetate-functionalized modifying resins sold by King
Industries under the brand name K-FLEX XM-B301.
[0085] Some functional silanes include a reactive component that
can bond or interact with the composition, a silane component that
can react with substrates and/or other silane modified materials
and a hydrolysable component. Some functional silanes having an
epoxy reactive component are sold by Momentive Performance
Materials Inc. of Connecticut.
[0086] The epoxy composition disclosed herein may contain, for
example, up to about 6 weight percent of adhesion promoter. The
adhesion promoter can be formulated into either or both of the
epoxy resin component or the curing agent component as
desirable.
Fillers
[0087] The curable composition can optionally comprise one or more
types of fillers, such as the various platy (flake like) fillers;
various ground or precipitated chalks; quartz powder; silica
powder; alumina; non-platy clays; dolomite; various fibers such as
carbon fibers, glass fibers, microballons, polymeric fibers; fused
silica; carbon black; metal oxides such as calcium oxide; metal
dioxides such as titanium dioxide; metal carbonates such as calcium
magnesium carbonate; barite; and silicate-like fillers of the
aluminum magnesium calcium silicate type, for example wollastonite
and chlorite. The filler can optionally be surface treated, for
example, by reaction with a coupling agent such as a silane. Filler
can be formulated into either or both of the epoxy resin component
or the curing agent component as desirable.
[0088] Adding micron sized silica particles does not increase
chemical resistance of the curable composition. Surprisingly,
adding nanometer sized (typically about 1 to about 100 nanometers,
for example about 20 nanometers) silica particles does appear to
improve chemical resistance of the curable composition. One
exemplary nanosilica material is NANOPDX F520 available from
Nanoresins AG in Geesthacht, Germany. Nanopox F520 is described as
a masterbatch of bisphenol F based epoxy resin system and 40%
silica particles having diameter of about 20 nanometers.
[0089] Useful amounts of filler typically range from about 0% by
weight to about 60% by weight of the total composition.
Advantageously, fillers are present in an amount from about 0% by
weight to about 45% by weight of the total composition.
Thixotrope
[0090] Any suitable thixotrope can be included in the present
inventive compositions. Suitable thixotropic agents include, for
example, Disparlon 6100, Disparlon 6200 (King Industries, Science
Rd., Norwalk, Conn.), organo clay, fumed silica, inert and/or
functional fillers, plastic fillers, and polyamide powder. Useful
amounts of thixotropes typically range from about 0% by weight to
about 30% by weight of the total composition. Desirably, a
thixotrope is present in an amount from about 1% by weight to about
10% by weight of the total composition.
Adjuvants
[0091] The curable composition can optionally comprise other common
adjuvants, such as flow auxiliaries, coupling agents (e.g.,
silanes), tackifiers, flame retardants, rheology control agents,
inhibitors, corrosion inhibitors, antioxidants, stabilizers,
thickeners, plasticizers, elastomers, thermoplastics, coloring
agents, shelf-life extenders (for example, zinc chloride),
industrial microbiostats, surfactants or wetting agents (for
example, Zonyl.RTM. FSO, which is sold by DuPont), polymerization
inhibitors, and other well-known additives, and combinations
thereof to further modify physical and chemical properties of the
epoxy composition and/or cured reaction products obtained from the
epoxy composition.
[0092] Depending on desired properties the relative proportions of
the individual components may vary within comparatively wide
limits. The adjuvants can be formulated into either or both of the
epoxy resin component or the curing agent component as
desirable.
[0093] The composition comprising each component can be prepared
separately by mixing together the constituents. In preparing the
epoxy resin component dry materials can be combined with liquid or
liquefied materials using conventional processes and equipment to
form a viscous, fluid epoxy resin component. The fluid epoxy resin
component can be packaged as convenient for storage and later use.
In preparing the curing agent component, dry materials can be
combined with the liquid or liquefied materials using conventional
processes and equipment to form a viscous, fluid curing agent
component. The curing agent component can be packaged as convenient
for storage and later use.
Methods of Use
[0094] The disclosed composition is suitable for use in potting and
sealing openings in electrical equipment for use in hazardous
locations.
[0095] The epoxy resin component and curing agent component are
stored separately. The two parts can be homogeneously mixed to form
the curable composition shortly before use. The mixed, curable
composition can typically be applied at about room temperature to
the aperture or area to be sealed. The mixed composition can have a
viscosity of about 8,000 cps to about 30,000 cps.
[0096] Once the epoxy resin component and curing agent component
are mixed the curing process starts. It is not necessary to heat
the mixed composition or substrates to begin the curing process.
Temperature control can optionally be used to modify the time
required for the mixed composition to cure. The mixed epoxy
composition can have a work life of about 20 to about 60 minutes
before the mixed composition reacts to a non-flowable but not fully
cured state.
[0097] In one embodiment the disclosed epoxy resin component and
curing agent component can each be components of a two part
adhesive package. Each component can be chemically separated and
packaged as convenient for use. The epoxy resin component and
curing agent component can typically be homogeneously mixed and
dispensed onto a substrate. For example, each component can be
contained in one chamber of a cartridge. The cartridges are placed
in a dual cartridge applicator so that actuation of the applicator
dispenses predefined volumes of the epoxy resin component and
curing agent component. The dispensed components are forced through
a mixing nozzle and the mixed composition is dispensed into an
aperture or other area to be sealed. Automated application
equipment for mixing and dispensing a two part curable composition
is known. The use of a liquid or flowable resin component and a
liquid or flowable curing agent component is advantageous for
mixing and dispensing and also allows the dispensed composition to
flow into the aperture or area to be sealed and around any wires or
other projections in the area to be sealed.
[0098] The following examples are included for purposes of
illustration so that the disclosure may be more readily understood
and are in no way intended to limit the scope of the disclosure
unless otherwise specifically indicated.
[0099] The following test methods are referred to in the
EXAMPLES.
Chemical Resistance (UL 674)
[0100] Note that UL 674 refers to requirements for sealed
equipment, including requirements for components such as sealants
used in the equipment. UL 1203 is an equivalent standard for
sealants only.
[0101] The epoxy resin component and curing agent component are
mixed and cured to form cylindrical specimens of cured sealant
material 0.5 inches in diameter and 0.75 inches long having ends
perpendicular to the sides of the cylinder. Each specimen is
measured and weighted. Three specimens are tested for compression
strength. The remaining specimens are segregated into six specimen
sets and each set is exposed for 7 days (168 hours) to saturated
vapors of one of the following chemicals.
[0102] a. acetic acid, glacial
[0103] b. acetone
[0104] c. ammonium hydroxide, 20% by weight
[0105] d. ASTM reference fuel C
[0106] e. diethyl ether
[0107] f. ethyl acetate
[0108] g. ethylene dichloride
[0109] h. furfural
[0110] i. n-hexane
[0111] j. methyl ethyl ketone
[0112] k. methanol
[0113] l. 2-nitropropane
[0114] m. toluene
[0115] After 168 hours of exposure three specimens from each set
are measured, weighed and observed for discoloration, swelling,
shrinking, cracking, crazing, leaching or dissolving. The other
three specimens in the set are individually placed between plates
in a compression testing machine and subjected to increasing
compressive loading at a crosshead speed of 0.1 inch per minute.
The load is applied perpendicular to the axis of the specimen
cylinder and the compressive force required to crack or break each
specimen is recorded.
[0116] Suitable materials for hazardous location use must retain at
least 85% of their compressive strength after 168 hours of exposure
to any chemical vapor in the panel and must not lose or gain more
than 1% of their initial weight after 168 hours of exposure to any
chemical vapor in the panel and must not discolor, swell, shrink,
crack, craze, leach or dissolve after 168 hours of exposure to any
chemical vapor in the panel.
Viscosity
[0117] Viscosity of composition components and freshly mixed epoxy
composition is tested using a Brookfield Viscometer with a #14
rotor turning at 10 revolutions per minute. Compositions and
components are tested at room temperature.
Example 1
[0118] A two part epoxy composition was made.
TABLE-US-00001 composition 1 amount material epoxy resin component
40-100% epoxy novolac resin produced by reacting phenol-
formaldehyde novolac and epichlorohydrin.sup.1 0-60% difunctional
epoxy resin produced by reacting bisphenol F and
epichlorohydrin.sup.2 0-20% epoxy novolac resin produced by
reacting phenolic novolac resin and epichlorohydrin.sup.3 curing
agent component 15-85% aliphatic amine.sup.4 10-60% amine
functional adduct of ethylene diamine (EDA) and liquid epoxy resin
with low residual EDA..sup.5 .sup.1D.E.N. 431 available from Dow
Chemical Company. .sup.2EPON Resin 863 available from Hexion
Specialty Chemicals. .sup.3EPON Resin 154 available from Hexion
Specialty Chemicals. .sup.4ANCAMINE 2422 available from Air
Products. .sup.5ANCAMINE 2410 available from Air Products.
[0119] Each component is separately prepared by mixing the
ingredients of that component to a homogeneous state. The epoxy
resin component had a viscosity of about 20,000 cps. The curing
agent component had a viscosity of about 10,000 cps.
[0120] The two components were homogeneously mixed at a ratio of 2
parts epoxy resin component to 1 part curing agent component by
volume. The mixed two part epoxy composition had an initial
viscosity of about 15,000 cps. The mixed two part epoxy composition
had a work life of less than 30 minutes; and was solid in less than
120 minutes at room temperature.
Example 1
[0121] A two part epoxy composition having a shortened cure time
can be made.
TABLE-US-00002 composition 1 amount material epoxy resin component
40-100% epoxy novolac resin produced by reacting phenol-
formaldehyde novolac and epichlorohydrin.sup.1 0-60% difunctional
epoxy resin produced by reacting bisphenol F and
epichlorohydrin.sup.2 0-20% epoxy novolac resin produced by
reacting phenolic novolac resin and epichlorohydrin.sup.3 curing
agent component 15-85% aliphatic amine.sup.4 10-60% amine
functional adduct of ethylene diamine (EDA) and liquid epoxy resin
with low residual EDA..sup.5 0-60% cure accelerator.sup.6 0-60%
cure accelerator.sup.7 .sup.1D.E.N. 431 available from Dow Chemical
Company. .sup.2EPON Resin 863 available from Hexion Specialty
Chemicals. .sup.3EPON Resin 154 available from Hexion Specialty
Chemicals. .sup.4ANCAMINE 2422 available from Air Products.
.sup.5ANCAMINE 2410 available from Air Products.
.sup.62-furanmethanol, cas number 98-00-0 .sup.7benzyl alcohol, cas
number 100-51-6
[0122] Each component can be separately prepared by mixing the
ingredients of that component to a homogeneous state. The epoxy
resin component had a viscosity of about 20,000 cps. The curing
agent component had a viscosity of about 10,000 cps.
[0123] The two components were homogeneously mixed at a ratio of 2
parts epoxy resin component to 1 part curing agent component by
volume. The mixed two part epoxy composition of EXAMPLE 1 (without
cure accelerator) had a work life of more than 60 minutes. The
mixed two part epoxy composition of EXAMPLE 1 (with cure
accelerator) had a work life of less than 30 minutes.
[0124] In a screening test the cured composition retained at least
85% of its compression strength after exposure to glacial acetic
acid, acetone and ethylene dichloride under the UL 674 test.
Example 2
[0125] A two part epoxy composition was made by combining the
following:
TABLE-US-00003 composition 2 amount material epoxy resin component
50-70% epoxy novolac resin produced by reacting phenol-
formaldehyde novolac and epichlorohydrin.sup.1 30-50% difunctional
epoxy resin produced by reacting bisphenol F and
epichlorohydrin.sup.2 0.1-1% Titanium dioxide powder.sup.3
0.005-0.02 air release agent.sup.4 curing agent component 30-50%
aliphatic amine.sup.5 30-50% amine functional adduct of ethylene
diamine (EDA) and liquid epoxy resin with low residual EDA.sup.6
10-30% 2-furanmethanol.sup.7 0.1-2.0% carbon black.sup.8 0.005-0.02
air release agent.sup.4 .sup.1D.E.N. 431 available from Dow
Chemical .sup.2EPON Resin 863 available from Hexion Specialty
Chemicals .sup.3R-900 available from E.I. DuPont de Nemours and
Company. .sup.4PC-1244 available from Monsanto Co. .sup.5ANCAMINE
2422 available from Air Products. .sup.6ANCAMINE 2410 available
from Air Products. .sup.7cas number 98-00-0 .sup.8MONARCH 700
available from Cabot Corp.
[0126] The ingredients of each component were separately combined
and mixed to a homogeneous state. The curing agent component was
degassed and nitrogen purged to lessen air entrapment. The epoxy
resin component had a white appearance; a specific gravity of about
1.20; and a viscosity of about 20,000 cps. The curing agent
component had a black appearance; a specific gravity of about 1.20;
and a viscosity of about 10,000 cps.
[0127] When mixed at 2 parts epoxy resin component to 1 part curing
agent component by volume the resulting mixture had a black
appearance and an initial viscosity of about 15,000 cps. The mixed
two part epoxy composition has a gel time of less than 30 minutes;
will be solid in less than 120 minutes and will cure to full
strength in 1 to 7 days at room temperature.
[0128] The cured composition passed the exposure test except for
glacial acetic acid (weight gain of 3.5%) and methanol (weight gain
of 1.9%). The cured composition retained at least 85% of its
compression strength after exposure to all of the UL 674 test panel
chemicals. The mixed and uncured epoxy composition had a maximum
150.degree. C. exotherm temperature when tested using Differential
Scanning calorimeter.
Example 3
[0129] A two part epoxy composition was made by combining the
following:
TABLE-US-00004 composition 3 amount material epoxy resin component
50-70% epoxy novolac resin produced by reacting phenol-
formaldehyde novolac and epichlorohydrin.sup.1 30-50% difunctional
epoxy resin produced by reacting bisphenol F and epichlorohydrin
and adding nano size silica.sup.2 0.1-1% Titanium dioxide
powder.sup.3 0.005-0.02 air release agent.sup.4 curing agent
component 30-50% aliphatic amine.sup.5 30-50% amine functional
adduct of ethylene diamine (EDA) and liquid epoxy resin with low
residual EDA.sup.6 10-30% 2-furanmethanol.sup.7 0.1-2.0% carbon
black.sup.8 0.005-0.02 air release agent.sup.4 .sup.1D.E.N. 431
available from Dow Chemical .sup.2NANOPOX F520 available from
NanoResins AG, Geesthacht, Germany. .sup.3R-900 available from E.I.
DuPont de Nemours and Company. .sup.4PC-1244 available from
Monsanto Co. .sup.5ANCAMINE 2422 available from Air Products.
.sup.6ANCAMINE 2410 available from Air Products. .sup.7cas number
98-00-0 .sup.8MONARCH 700 available from Cabot Corp.
[0130] The ingredients of each component were separately combined
and mixed to a homogeneous state. The curing agent component was
degassed and nitrogen purged to lessen air entrapment. The epoxy
resin component had a white appearance; a specific gravity of about
1.20; and a viscosity of about 20,000 cps. The curing agent
component had a black appearance; a specific gravity of about 1.20;
and a viscosity of about 10,000 cps.
[0131] When mixed at 2 parts epoxy resin component to 1 part curing
agent component by volume the resulting mixture had a black
appearance and an initial viscosity of about 15,000 cps. The mixed
two part epoxy composition has a gel time of less than 30 minutes;
will be solid in less than 120 minutes and will cure to full
strength in 1 to 7 days at room temperature.
[0132] The cured composition passed the exposure test except for
glacial acetic acid (weight gain of 1.4%; length change of 1.4% and
diameter change of 1.6%) and methanol (weight gain of 1.9%). The
cured composition retained at least 85% of its compression strength
after exposure to all of the UL 674 test panel chemicals. The mixed
and uncured epoxy composition had a maximum 150.degree. C. exotherm
temperature when tested using Differential Scanning
calorimeter.
[0133] It is believed that cured reaction products of composition 3
can pass all of the UL 674 chemical resistance tests if the amine
functional adduct of ethylene diamine (EDA) and liquid epoxy resin
is replaced with an amine functional adduct of an amine and a
bisphenol F resin.
[0134] As an alternative, UL 674 section 45.8 allows tests to
determine resistance of the sealing compound to chemicals to be
conducted on a complete sample or subassembly representative of the
construction to be approved and incorporating the sealing compound
as intended in the final assembly but without cables or conductors.
It is believed that an electrical assembly incorporating sealing
composition 3 can pass UL 674 under this alternative.
Example 4
[0135] Two part epoxy compositions A-V were made by combining
materials shown in the following tables. The materials of each
component were separately combined and mixed to a homogeneous
state. The curing agent component was degassed and nitrogen purged
to lessen air entrapment. The two components were homogeneously
mixed at a ratio of 2 parts epoxy resin component to 1 part curing
agent component by volume.
TABLE-US-00005 comparative compositions A-E A B C D E material
amount (wt %) epoxy resin component epoxy novolac resin produced by
65 65 58.5 58.5 51.6 reacting phenol-formaldehyde novolac and
epichlorohydrin.sup.1 difunctional epoxy resin produced by 20 20 18
18 15.9 reacting bisphenol F and epichlorohydrin.sup.2 epoxy
novolac resin produced by 14 14 12.6 12.6 11.1 reacting phenolic
novolac resin and epichlorohydrin.sup.3 low viscosity aliphatic
triglycidyl 1 1 0.9 0.9 0.8 ether.sup.4 difunctional epoxy resin
produced by 0 0 10 10 20.6 reacting bisphenol A and
epichlorohydrin.sup.5 curing agent component aliphatic amine.sup.6
9.3 9.5 7.9 8.0 6.3 amine functional adduct of ethylene 0 0 0 0 0
diamine (EDA) and liquid epoxy resin with low residual EDA.sup.7
modified amine.sup.8 43.7 58.6 44.9 59.9 45.2 modified aliphatic
amine.sup.9 43.7 28.6 44.4 28.8 45.2 modified aliphatic
amine.sup.10 3.3 3.3 3.3 3.3 3.3 .sup.1D.E.N. 431 available from
Dow Chemical Company. .sup.2EPON Resin 863 available from Hexion
Specialty Chemicals. .sup.3EPON Resin 154 available from Hexion
Specialty Chemicals. .sup.4HELOXY 48 available from Hexion
Specialty Chemicals. .sup.5EPON Resin 828 available from Hexion
Specialty Chemicals. .sup.6ANCAMINE 2422 available from Air
Products. .sup.7ANCAMINE 2410 available from Air Products.
.sup.8ANCAMINE 2334 available from Air Products. .sup.9ANCAMINE
2432 available from Air Products. .sup.10ANCAMINE 1608 available
from Air Products.
TABLE-US-00006 comparative compositions F-J F G H I J material
amount (wt %) epoxy resin component epoxy novolac resin produced by
51.6 65 65 58.5 58.5 reacting phenol-formaldehyde novolac and
epichlorohydrin.sup.1 difunctional epoxy resin produced by 15.9 20
20 18 18 reacting bisphenol F and epichlorohydrin.sup.2 epoxy
novolac resin produced by 11.1 14 14 12.6 12.6 reacting phenolic
novolac resin and epichlorohydrin.sup.3 low viscosity aliphatic
triglycidyl 0.8 1 1 0.9 0.9 ether.sup.4 difunctional epoxy resin
produced by 20.6 0 0 10 10 reacting bisphenol A and
epichlorohydrin.sup.5 curing agent component aliphatic amine.sup.6
6.5 7.4 7.6 5.9 6.2 amine functional adduct of ethylene 0 15 15 15
15 diamine (EDA) and liquid epoxy resin with low residual EDA.sup.7
modified amine.sup.8 60.7 37.2 50 37.9 51 modified aliphatic
amine.sup.9 29.5 37.2 24.1 37.9 24.5 modified aliphatic
amine.sup.10 3.3 3.3 3.3 3.3 3.3 .sup.1D.E.N. 431 available from
Dow Chemical Company. .sup.2EPON Resin 863 available from Hexion
Specialty Chemicals. .sup.3EPON Resin 154 available from Hexion
Specialty Chemicals. .sup.4HELOXY 48 available from Hexion
Specialty Chemicals. .sup.5EPON Resin 828 available from Hexion
Specialty Chemicals. .sup.6ANCAMINE 2422 available from Air
Products. .sup.7ANCAMINE 2410 available from Air Products.
.sup.8ANCAMINE 2334 available from Air Products. .sup.9ANCAMINE
2432 available from Air Products. .sup.10ANCAMINE 1608 available
from Air Products.
TABLE-US-00007 comparative compositions H-O K L M N O material
amount (wt %) epoxy resin component difunctional epoxy resin
produced by 100 100 100 100 100 reacting bisphenol A and
epichlorohydrin.sup.1 curing agent component aliphatic amine.sup.2
53.5 50.7 48 100 94.7 modified amine.sup.3 0 0 0 100 94.7
TEPA.sup.4 0 1.7 3.5 0 0 2-furanmethanol.sup.5 46.5 47.6 48.5 0 2.6
.sup.1EPON Resin 828 available from Hexion Specialty Chemicals.
.sup.2ANCAMINE 2422 available from Air Products. .sup.3ANCAMINE
2334 .sup.4tetraethylenepentamine - mixture of four TEPA
ethyleneamines including: TEPA CAS #000112-57-2,
N-(2-aminoethyl)-N'-{2-(2-aminoethyl)amino}ethyl}-1,2-ethanediamine;
AETETA CAS #031295-46-2,
4-(2-aminoethyl)-N-(2-aminoethyl)-N'-{2-{(2-aminoethyl)amino}ethyl}-1,2-e-
thanediamine; APEEDA CAS #031295-54-2,
1-(2-aminoethyl)-4-[(2-aminoethyl)-amino]ethyl]-piperazine; PEDETA
CAS #031295-49-5,
1-[2-[[2-[(2-aminoethyl)amino]ethyl]-amino]ethyl]-piperazine
.sup.5cas number 98-00-0
TABLE-US-00008 comparative compositions P-T P Q R S T material
amount (wt %) epoxy resin component difunctional epoxy resin
produced by 100 100 100 100 100 reacting bisphenol A and
epichlorohydrin.sup.1 curing agent component aliphatic amine.sup.2
5.3 10.8 21.6 43 48 modified amine.sup.3 89.8 79.6 59.3 19.2 9.9
TEPA.sup.4 0 0 0 0 0 2-furanmethanol.sup.5 4.9 9.6 19.1 37.8 42.1
.sup.1EPON Resin 828 available from Hexion Specialty Chemicals.
.sup.2ANCAMINE 2422 available from Air Products. .sup.3ANCAMINE
2334 .sup.4tetraethylenepentamine - mixture of four TEPA
ethyleneamines including: TEPA CAS #000112-57-2,
N-(2-aminoethyl)-N'-{2-(2-aminoethyl)amino}ethyl}-1,2-ethanediamine;
AETETA CAS #031295-46-2,
4-(2-aminoethyl)-N-(2-aminoethyl)-N'-{2-{(2-aminoethyl)amino}ethyl}-1,2-e-
thanediamine; APEEDA CAS #031295-54-2,
1-(2-aminoethyl)-4-[(2-aminoethyl)-amino]ethyl]-piperazine; PEDETA
CAS #031295-49-5,
1-[2-[[2-[(2-aminoethyl)amino]ethyl]-amino]ethyl]-piperazine
.sup.5cas number 98-00-0
TABLE-US-00009 comparative compositions U-V U V material amount (wt
%) epoxy resin component difunctional epoxy resin produced by 100
100 reacting bisphenol A and epichlorohydrin.sup.1 curing agent
component aliphatic amine.sup.2 21.6 42 modified amine.sup.3 54.5
16.3 TEPA.sup.4 1.7 1.7 2-furanmethanol.sup.5 22.2 40 .sup.1EPON
Resin 828 available from Hexion Specialty Chemicals. .sup.2ANCAMINE
2422 available from Air Products. .sup.3ANCAMINE 2334
.sup.4tetraethylenepentamine - mixture of four TEPA ethyleneamines
including: TEPA CAS #000112-57-2,
N-(2-aminoethyl)-N'-{2-(2-aminoethyl)amino}ethyl}-1,2-ethanediamine;
AETETA CAS #031295-46-2,
4-(2-aminoethyl)-N-(2-aminoethyl)-N'-{2-{(2-aminoethyl)amino}ethyl}-1,2-e-
thanediamine; APEEDA CAS #031295-54-2,
1-(2-aminoethyl)-4-[(2-aminoethyl)-amino]ethyl]-piperazine; PEDETA
CAS #031295-49-5,
1-[2-[[2-[(2-aminoethyl)amino]ethyl]-amino]ethyl]-piperazine
.sup.5cas number 98-00-0
[0136] UL 674 specifies weight changes of less than 1%.
Compositions A through J had weight gains of 10.6% to 12.6% after
exposure to glacial acetic acid vapors per UL 674. Compositions A
through J had weight gains of 4.1% to 6.7% after exposure to
acetone vapors per UL 674. UL 674 specifies a retained compression
strength (crush force) of .gtoreq.85%. Compositions K through V had
an unacceptable loss of compression strength after exposure to
either acetone or glacial acetic acid vapors per UL 674 as shown
below.
TABLE-US-00010 K M Q T U V % retention after exposure 70.4 74.6
55.8 68.6 66 67.2 to glacial acetic acid vapor % retention after
exposure 78.6 82.3 61.3 76.8 72.5 77.4 to acetone vapor
[0137] As seen from comparative compositions A-V almost all epoxy
compositions will not satisfy the requirements of UL 674 and will
not be suited for use in hazardous locations as they will not
retain at least 85% of their compressive strength after 168 hours
of exposure to a chemical vapor in the panel or they will lose or
gain more than 1% of their initial weight after 168 hours of
exposure to a chemical vapor in the panel or they will discolor,
swell, shrink, crack, craze, leach or dissolve after 168 hours of
exposure to a chemical vapor in the panel. Compositions 1-3 provide
epoxy compositions that are believed to satisfy at least the
alternative requirements of UL 674. Replacing the amine adduct in
compositions 1-3 with an amine adduct of bisphenol F epoxy is
believed to increase chemical resistance and allow cured reaction
product samples to pass the UL 674 requirements. These epoxy
compositions are unusual and surprising in their ability to satisfy
most or all of these UL requirements.
[0138] While preferred embodiments have been set forth for purposes
of illustration, the foregoing description should not be deemed a
limitation of the disclosure herein. Accordingly, various
modifications, adaptations and alternatives may occur to one
skilled in the art without departing from the spirit and scope of
the present disclosure.
* * * * *