U.S. patent application number 10/269800 was filed with the patent office on 2004-04-15 for two-part epoxy adhesives with improved flexibility and process for making and using same.
Invention is credited to Hachikian, Zakar Raffi.
Application Number | 20040072927 10/269800 |
Document ID | / |
Family ID | 32068879 |
Filed Date | 2004-04-15 |
United States Patent
Application |
20040072927 |
Kind Code |
A1 |
Hachikian, Zakar Raffi |
April 15, 2004 |
Two-part epoxy adhesives with improved flexibility and process for
making and using same
Abstract
A two-part epoxy adhesive having a resin component containing a
mixture of an epoxy resin and an internally flexibilized epoxy
resin and a hardener component containing a mixture of a
flexibilizer and an unmodified or modified aliphatic amine or
combinations thereof. The resin component and hardener component
are mixed and applied to substrates, or applied to substrates and
mixed, an then allowed to cure yielding a cured epoxy resin having
a tensile elongation at room temperature of greater than 30%. The
initial curing time is less than 3 hours.
Inventors: |
Hachikian, Zakar Raffi;
(Belmont, MA) |
Correspondence
Address: |
Killworth, Gottman, Hagan & Schaeff, L.L.P.
Suite 500
One Dayton Centre
Dayton
OH
45402-2023
US
|
Family ID: |
32068879 |
Appl. No.: |
10/269800 |
Filed: |
October 14, 2002 |
Current U.S.
Class: |
523/457 |
Current CPC
Class: |
C08L 63/00 20130101;
Y10T 428/31511 20150401; C09J 2463/00 20130101; C09J 5/06 20130101;
C08L 2666/02 20130101; C09J 163/00 20130101; C08G 59/18 20130101;
C09J 163/00 20130101; C08L 2666/02 20130101 |
Class at
Publication: |
523/457 |
International
Class: |
C08L 063/00 |
Claims
What is claimed is:
1. A two-part epoxy adhesive comprising: a) a resin component
comprising a mixture of epoxy resin and an internally flexibilized
epoxy resin, and b) a hardener component comprising a mixture of a
flexibilizer and an unmodified or modified aliphatic amine or
combinations thereof, wherein after said resin component and said
hardener component are mixed and reacted the cured epoxy adhesive
has a tensile elongation at room temperature of greater than
30%.
2. The two-part epoxy adhesive of claim 1 wherein the epoxy
adhesive has an initial curing time of less than 3 hours.
3. The two-part epoxy adhesive of claim 1 wherein said
resin-component further includes a plasticizer/accelerator, a
coupling agent, fillers, and a thixotropic agent.
4. The two-part epoxy adhesive of claim 1 wherein said hardener
component further includes an accelerator and a thixotropic
agent.
5. The two-part epoxy adhesive of claim 1 wherein said resin
component comprises by weight: 30-75% epoxy resin, 5-40% internally
flexibilized epoxy resin, 5-40% plasticizer/accelerator, 0.1-1%
coupling agent, 11-45% filler, and 1-8% thixotrophic agent.
6. The two-part epoxy adhesive of claim 5 wherein said epoxy resin
is a Bisphenol A epoxy resin, said internally flexibilized epoxy
resin is an internally flexibilized Bisphenol A type epoxy resin,
said plasticizer/accelerator is a phenol based
plasticizer/accelerator, said coupling agent is an epoxide
functional silane base coupling agent and said filler is a mixture
of limestone filler and white pigment.
7. The two-part epoxy adhesive of claim 6 wherein said hardener
component comprises by weight: 20-80% flexibilizer 5-30% unmodified
aliphatic amine, 1-10% accelerator 10-50% modified aliphatic amine,
and 1-8% thixotropic agent.
8. The two-part epoxy adhesive of claim 7 wherein said flexibilizer
is an amine terminated butadiene acrylonitrile adduct, said
unmodified aliphatic amine is an unmodified glycol ether base
aliphatic amine, said accelerator is a tertiary amine accelerator,
and said modified aliphatic amine is an AEP base modified
amine.
9. A two-part epoxy adhesive comprising: a) a resin component
comprising a mixture of epoxy resin and an internally flexibilized
epoxy resin, and b) a hardener component comprising a mixture of
flexibilizer and an unmodified or modified aliphatic amine or
combinations thereof, wherein the reactive mixture of said resin
component and said hardener component has an initial curing time of
about 1.5-2 hours and after curing the epoxy adhesive has a tensile
elongation at room temperature of greater than 120%.
10. The two-part epoxy adhesive of claim 9 comprising: a) a resin
component comprising a mixture of: 40-45% Bisphenol A epoxy resin,
8-15% internally flexibilized Bisphenol A type epoxy resin, 10-20%
phenol base plasticizer/accelerator, 0.3-0.6% epoxide functional
silane base coupling agent, 15-25% limestone filler, 0.5-2% white
pigment and 4-6% thixotrophic agent, and b) a hardener component
comprising a mixture of: 40-45% amine terminated butadiene
acrylonitrile adduct, 7-15% unmodified glycol ether base aliphatic
amine 5-8% tertiary amine accelerator, 25-40% AEP base modified
amine, and 1-8% thixotrophic agent.
11. The process of adhering at least two substrate surfaces to each
other comprising the acts of: intercalating between said surfaces
an adhesive comprising a reactive mixture of: a. a resin component
comprising a mixture of epoxy resin and internally flexible epoxy
resin, and b. a hardener component comprising a mixture of a
flexibilizer and an unmodified or modified aliphatic amine or
combinations thereof, and allowing said adhesive to cure, whereby
said cured adhesive has a tensile elongation at room temperature of
greater than 30%.
12. The process of claim 11 wherein in said act of curing it takes
less than 3 hours for initial curing.
13. The process of claim 12 wherein said act of intercalating
includes dispensing the resin component and hardener component in
equal parts by volume and mixing until the mixture is relatively
homogeneous and is applied relatively evenly to the substrates.
14. The process of claim 11 wherein said resin-component further
includes a plasticizer/accelerator, a coupling agent, fillers, and
a thixotropic agent.
15. The process of claim 11 wherein said hardener component further
includes an accelerator and a thixotropic agent.
16. The process of claim 11 wherein said resin component comprises
by weight: 30-75% epoxy resin, 5-40% internally flexibilized epoxy
resin, 5-40% plasticizer/accelerator, 0.1-1% coupling agent, 11-45%
filler, and 1-8% thixotrophic agent.
17. The process of claim 16 wherein said epoxy resin is a Bisphenol
A epoxy resin, said internally flexibilized epoxy resin is an
internally flexibilized Bisphenol A type epoxy resin, said
plasticizer/accelerator is a phenol based plasticizer/accelerator,
said coupling agent is an epoxide functional silane base coupling
agent and said filler is a mixture of limestone filler and white
pigment.
18. The process of claim 17 wherein said hardener component
comprises by weight: 20-80% flexibilizer 5-30% unmodified aliphatic
amine, 1-10% accelerator 10-50% modified aliphatic amine, and 1-8%
thixotropic agent.
19. The process of claim 18 wherein said flexibilizer is an amine
terminated butadiene acrylonitrile adduct, said unmodified
aliphatic amine is an unmodified glycol ether base aliphatic amine,
said accelerator is a tertiary amine accelerator, and said modified
aliphatic amine is an AEP base modified amine.
20. The process of claim 11 wherein: a) said resin component
comprises a mixture of: 40-45% Bisphenol A epoxy resin, 8-15%
internally flexibilized Bisphenol A type epoxy resin, 10-20% phenol
base plasticizer/accelerator, 0.3-0.6% epoxide functional silane
base coupling agent, 15-25% limestone filler, 0.5-2% white pigment
and 4-6% thixotrophic agent, and b) said hardener component
comprises a mixture of: 40-45% amine terminated butadiene
acrylonitrile adduct, 7-15% unmodified glycol ether base aliphatic
amine, 5-8% tertiary amine accelerator, 25-40% AEP base modified
amine, and 1-8% thixotrophic agent.
21. A process for making a two-part epoxy adhesive comprising:
preparing a resin component by mixing an epoxy resin, an internally
flexibilized epoxy resin, a plasticizer/accelerator, a coupling
agent, fillers, and a thixotropic agent, and preparing a hardener
component comprising a mixture of a flexibilizer, an unmodified or
modified aliphatic amine or combinations thereof, an accelerator a
thixotropic agent.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to two-part epoxy adhesives which
have improved flexibility and a process for making and using them.
More particularly, this invention relates to an improved epoxy
adhesive which has good adhesions to various substrates, especially
where a high level of elongation is needed due to thermal expansion
and contraction of the substrates or where the substrates are
exposed to thermal shock. It can also be used at low operating
temperatures.
[0002] Polymeric compositions based on the commercially available
Bisphenol A based epoxy resins cured by one or more of the active
hydrogen compounds such as polyamines, polyacids, polyphenols, and
the like exhibit good adhesion properties towards various
substrates including metal and plastics, but most of these
adhesives are rigid, stiff and brittle polymers. There is also a
problem of shrinkage occurring in the epoxide adhesive during the
curing, thus building undesired stress in the substrates as well as
the adhesive at the glue line. Accordingly, it has been suggested
that flexibilizers such as butadiene rubbers, urethane elastomers,
and the like be added to the epoxy resins.
[0003] Past attempts to modify epoxies involved reacting them with
copolymers of butadiene, acrylonitrile or other "rubber"-based
compositions. See Journal of Applied Polymer Science, Vol. 26, pp.
907-919 (1981). By reacting an epoxy with those compounds and then
processing the modified composition to induce in situ phase
separation, "rubber rich" domains within the epoxy composition are
created. Those domains improve the toughness of the cured epoxy
matrix once it is formed. However, while such modified epoxy
compositions are tougher and less brittle at room temperature,
improvements at lower temperatures prove to be, at best, marginal.
Further, using the above-mentioned rubber-based material incurs
processing problems due to an increase in viscosity of the adhesive
mixture.
[0004] Accordingly, various epoxy adhesive formulations have been
proposed to address these problems. See, for example U.S. Pat. No.
4,728,384; 5,098,505; 5,218,063; 5,367,006 and 5,679,730. More
recently, there has been introduced Mr. Sticky's Underwater Glue.
According to the website at underwaterglue.com, this is an improved
two-part epoxy glue having a flexibility (elongation) of 30%, very
good shock dampening, and flexible bonds. It has a mixture working
life of 30-60 minutes and an initial curing time of 3-4 hours. The
complete curing time is 24 hours.
[0005] Still, there is a need for an even more improved two-part
epoxy adhesive.
SUMMARY OF THE INVENTION
[0006] That need is met by the present invention which provides a
two-part epoxy adhesive with improved flexibility and provides a
process for adhering at least two substrate surfaces to each other
with that adhesive.
[0007] The two-part epoxy adhesive has a resin component made up of
a mixture of an epoxy resin such as a standard, undiluted, liquid
Bishpenol-A resin, and an internally flexibilized epoxy resin which
is also preferably a Bisphenol A type resin. The resin component
may also contain a plasticizer/accelerator, such as a phenol base
plasticizer/accelerator, a coupling agent such as an epoxide
functional silane base coupling agent, fillers, such as limestone
filler and titanium dioxide white pigment, and a thixotropic
agent.
[0008] The percentages by weight in the preferred embodiment of the
resin component are:
[0009] 30-75% epoxy resin,
[0010] 5-40% plasticizer/accelerator,
[0011] 0.1-1% coupling agent,
[0012] 11-45% filler, and
[0013] 1-8% thixotropic agent.
[0014] The two-part epoxy adhesive has a hardener component made up
of a mixture of a flexibilizer, such as an amine terminated
butadiene acrylonitrile adduct, and an unmodified aliphatic amine,
such as an unmodified glycol ether base aliphatic amine or a
modified aliphatic amine such as an Aminoethyl-piperozine (AEP)
base modified amine, or combinations thereof. The hardener
component may also contain an accelerator, which is preferably a
tertiary amine accelerator, as well as a thixotropic agent.
[0015] The percentages by weight in the preferred embodiment of the
hardener component are:
[0016] 20-80% flexibilizer,
[0017] 5-30% unmodified aliphatic amine,
[0018] 1-10% accelerator,
[0019] 10-50% modified aliphatic amine, and
[0020] 1-8% thixotropic agent.
[0021] The most preferred two-part epoxy adhesive has:
[0022] a) a resin component comprising a mixture of:
[0023] 40-45% Bisphenol A epoxy resin,
[0024] 8-15% internally flexibilized Bisphenol A type epoxy
resin,
[0025] 10-20% phenol base plasticizer/accelerator,
[0026] 0.3-0.6% epoxide functional silane base coupling agent,
[0027] 15-25% limestone filler,
[0028] 0.5-2% white pigrnent and
[0029] 4-6% thixotropic agent, and
[0030] b) a hardener component comprising a mixture of:
[0031] 40-45% amine terminated butadiene acrylonitrile adduct,
[0032] 7-15% unmodified glycol ether base aliphatic amine,
[0033] 5-8% tertiary amine accelerator,
[0034] 25-40% AEP base modified amine, and
[0035] 1-8% thixotropic agent.
[0036] After the resin component and hardener component are mixed
and reacted the cured epoxy adhesive has a tensile elongation at
room temperature of greater than 30%, and the most preferred
embodiment thereof has a tensile elongation at room temperature of
greater than 120%.
[0037] In addition, the reactive mixture of resin component and
hardener component has an initial cure time of less than 3 hours,
and the most preferred embodiment thereof has an internal cure time
of about 1.5-2 hours. The complete cure takes place in
approximately 24 hours.
[0038] The epoxy adhesive of the present invention has good
adhesion to various substrates including concrete, metals,
plastics, and wood and is especially useful in applications where a
high level of elongation (for example, when bonding to flexible
PVC) is needed due to thermal expansion and contraction of the
substrates (for example when bonding metal to plastic) or where the
substrates are exposed to thermal shock. It is also useful in
applications having low operating temperatures. While the preferred
application temperature range is 40-100.degree. F., it may be used
at temperatures of up to about 180-200.degree. F. and down to below
zero to adhere at least two substrate surfaces to each other by
intercalating between those surfaces an adhesive, formed from the
reactive mixture of the resin component and the hardener component
disclosed above, by applying these components in equal amounts
(parts by volume) from a double-barreled cartridge, mixing well
until the mixture is relatively homogeneous and applied relatively
evenly to the substrates, and then allowing the adhesive to
cure.
DETAILED DESCRIPTION OF THE INVENTION
[0039] The present invention provides an improved two-part epoxy
adhesive having a resin component and a hardener component which
can be dispensed from a double-barreled cartridge in equal parts by
volume concurrently and then mixed until relatively homogeneous. As
is known, dispensing and mixing may be prior to application of the
relatively homogeneous mixture to one or more of the substrates, or
it may take place on one or more of the substrates. Likewise, a
double-barreled cartridge need not be used; the resin component and
hardener component can be dispensed from separate containers and,
then mixed. In any event, the reactive mixture of components is
applied relatively evenly between substrates which are joined, and
the adhesive is allowed to cure.
[0040] The initial cure takes place in less than 3 hours, and, with
the two-part epoxy adhesive of the preferred embodiment, it has
been found that generally the initial curing time is about 1.5 to
2.0 hours. Complete cure then takes place in about 24 hours.
[0041] After cure, the epoxy adhesive of the present invention has
a tensile elongation at room temperature of greater than 30%, and
with the two-part epoxy adhesive of the preferred embodiment it can
exceed 120%. Elongation is important when bonding flexible
materials like flexible polyvinyl chloride (PVC) or
acrylonitrile-butadiene-styrene (ABS) and in those applications
where there is a large amount of displacement between substrates or
where the degree of thermal expansion and contraction is of
concern.
[0042] The improved flexibility of the two-part epoxy resin of the
present invention is achieved by using a resin component and a
hardener component having a unique combination of ingredients. The
resin component is a mixture of epoxy resin, which may be a
standard, undiluted, liquid Bisphenol A resin such as EPON 828 from
Shell Oil Company, Houston, Tex., and an internally flexibilized
Bisphenol A type epoxy resin such as Araldite PY 322 available from
Ciba Specialty Chemicals, Tarrytown, N.Y. The internally
flexibilized epoxy resins have flexible segments in their backbone.
Therefore when they react and become a part of the adhesive
network, they provide flexibility into the rigid polymer via their
soft/flexible segments. While Bisphenol A type resins are
preferred, Bispehnol-F type resins or mixtures of the two can be
used as either the core epoxy resin, or the internally flexibilized
epoxy resin, or both.
[0043] The resin component may also contain a
plasticizer/accelerator which may be a phenol base
plasticizer/accelerator such as Nonylphenol from GE Specialty
Chemicals, Morgantown, W. Va. Other plasticizers/accelerators may
be used but Nonylphenol is preferred since it has minimal effect on
physical properties and is a mild accelerator.
[0044] A small amount of coupling agent is also preferably added to
the resin component. Preferred is an epoxide functional silane base
coupling agent such as Silane Z-6040 from Dow Corning Corporation,
Midland, Mich. That type of coupling agent, has dual reactivity,
meaning that silanes, as is known, possess both organic and
inorganic functionality that allow them to react with organic
polymers and inorganic surfaces. An amino silane or other types of
coupling agents could be used to get the same effect.
[0045] Any number of types of fillers can be added to the resin
component. Preferred are limestone filler such as Marble White 325
from Filler Products Inc. and Titanium Dioxide R-900 white pigment
from DuPont de Nemours, Wilmington, Del. Other white fillers and
white pigments may be used for a white or off white colored resin
component. If another color is desired, then fillers and pigments
of the desired color would be used.
[0046] Finally, the resin component can contain a thixotropic agent
such as Cab-o-Sil 720 from Cabot Corporation, Boston, Mass. There
are numerous other thixotropic agents that could be used along with
the fillers to obtain a resin component having the desired
viscosity, i.e. one which permits dispensing as discussed
above.
[0047] In preparation of the resin component, the core epoxy resin
(EPON 828), the reactive flexibilizer (Araldite PY 322), the
plasticizer/accelerator (Nonylphenol), and the coupling agent
(Silane Z-6040) are mixed until the mixture is relatively
homogenous, and then the fillers (Marble White 325 and Titanium
Dioxide R-900) are added and mixed. As the last step, the
thixotropic agent (Cab-o-Sil 720) is added and mixed until it is
dispersed therein.
[0048] The preferred weight percentage range of the ingredients in
the resin component and the most preferred range are as
follows:
1 RESIN COMPONENT Preferred Most Preferred Epoxy Resin 30-75 40-45
Internally Flexibilized Resin 5-40 8-15 Plasticizer/Accelerator
5-40 10-20 Coupling Agent 0.1-1 0.3-0.6 Limestone Filler 10-40
15-25 White Pigment 1-5 0.5-2 Thixotropic Agent 1-8 4-6
[0049] The hardener component contains a mixture of a flexibilizer,
which may be an amine terminated butadiene acrylonitrile adduct,
such as Hycor ATBN 1300.times.16 from B.F. Goodrich, Akron, Ohio,
and an unmodified aliphatic amine, such as an unmodified glycol
ether base aliphatic amine (i.e. Ancamine 1922A from Air Products,
Pittsburgh, Pa.), or a modified base aliphatic amine such as an
Aminoethyl-piperozine (AEP) base modified (Ancamine 1767, also from
Air Products), or preferably a combination of the two. The
flexibilizer does not have to be an amine terminated butadient
acrylonitrile (ATBN) but it should be similar in mixture. For
example, a carboxyl terminated butadiene acrylonitride (CTBN) can
be used. Likewise, unmodified aliphatic amines other than glycol
ether based ones can be used as long as they contribute to the
toughness, resiliency and shock resistance of the cured adhesive
and modified aliphatic amines other than AEP based ones can be used
as long as they contribute to the toughness and speed up the cure,
as do the AEP based ones.
[0050] The hardener component may also contain an accelerator,
which may be a tertiary amine accelerator, such as Ancamine K-54
also from Air Products and a thixotropic agent, which can be the
same as the one used in the resin component such as Cab-o-Sil 720
from Cabot. As was the case with the resin component, any
thixotropic agent in an amount sufficient to give the desired
viscosity may be used.
[0051] In preparation of the hardener component, all of the
liquids, i.e., everything except the thixotropic agent, are blended
and then the thixotropic agent is added and mixed until well
dispersed therein.
[0052] The preferred weight percentage range of the ingredients in
the hardener component and the most preferred range are as
follows:
2 Hardener: Component Preferred % Most Preferred % Flexibilizer
20-80 40-45 Unmodified Aliphatic Amine 5-30 7-15 Modified Aliphatic
Amine 10-50 25-40 Accelerator 1-10 5-8 Thixotropic Agent 1-8
5-8
[0053] While two-part epoxy adhesives of the present invention are
preferably used at 40-100.degree. F. they may be at temperatures up
to about 180-200.degree. F., and are particularly useful at low
temperatures down below about 0.degree. F. They may be used for
indoor or outdoor repair situations or in manufacturing OEM
products where strong, flexible, but relatively permanent bonds are
desired. They have good adhesion to various substrates including
concrete, metals, such as steel, aluminum, brass, etc, plastics,
such as ABS, PVC, flexible PVC, fiberglass, acrylics,
polyurethanes, etc., and wood.
EXAMPLE
[0054] The resin component and hardener component were prepared by
mixing the following ingredients as described above to prepare the
two-part epoxy adhesive of the present invention:
3 Parts by Tradename Ingredient Weight RESIN Epon 828 Bisphenol A
Epoxy Resin 49.5 Araldite PY322 Internally Flexibilized 10.0
Bisphenol A Epoxy Resin Nonylphenol Plasticizer/Accelerator 16.5
Silene Z-6040 Coupling Agent 0.5 Marble White 325 Limestone Filler
17.0 Titanium Dioxide R-900 White Pigment 1.0 Cab-o-Sil 720
Thixotrophic Agent 5.5 HARDENER Hycar ATBN 1300x-16 Flexibilizer
41.7 Ancamine 1922A Unmodified Aliphatic Amine 10.6 Ancamine 1767
Modified Aliphatic Amine 35.0 Ancamine K-54 Accelerator 6.7
Cab-o-Sil 720 Thixotrophic Agent 6.0
[0055] The properties of the two-part epoxy adhesive were then
compared to Mr. Sticky's Underwater Glue with the following
results:
4 Mr Sticky's Underwater Underwater Present Mr Sticky's Glue (data
Glue (tested Invention Properties reported) data) (tested data)
Color Off-White Off-White Off-White Viscosity @ 20.degree. C. Resin
35,000 Hardener 200,000 36,000 Mixed Viscosity 35,000 Density
(gr./cc) Resin 1.25 1.25 Hardener 0.94 0.97 Mixing Ratio by weight
4:3 1.2:1 by volume 1 to 1 1 to 1 Working Life 30-60 minutes 25-30
minutes Gell Time (25 gram) 3-4 hours 1.5-2 hours Full Cure 24
hours 24 hours Application Temperature 40.degree.-100.degree. F.
40.degree.-100.degree. F. TYPICAL PROPERTIES OF CURED PRODUCT
Tensile elongation 30% 125% Tensile Modulus 76,000 psi Tensile
Strength 2,000 psi 1,540 psi Flexural Modulus 82,000 psi LAP SHEAR
TESTING CRS/CRS @ .010" 1,800 psi 1,600 psi 1,600 psi RIGID PVC/PVC
1,300 psi 500 psi 1,100 psi ABRAIDED RIGID PVC/PVC 1,800 psi 850
psi 1,140 psi ABS/AB 400 psi 400 psi 800 psi ABRAIDED ABS/ABS 600
psi 710 psi 875 psi 180.degree. T-PEEL TESTING RIGID PVC/FLEXIBLE
PVC 12.6 pli 10.4 pli 10.5 pli ABRAIDED RIGID PVC/ FLEXIBLE PVC
25.4 pli 6 pli 10.1 pli ABS/FLEXIBLE/PVC 13.0 pli 3 pli 10 pli
ABRAIDED ABS/FLEXIBLE/ N/A 11.1 pli 13.4 pli PVC
* * * * *