U.S. patent number RE37,683 [Application Number 09/770,036] was granted by the patent office on 2002-04-30 for adhesive composition and method for providing water-tight joints in single-ply roofing membranes.
This patent grant is currently assigned to Adco Products, Inc.. Invention is credited to Brian J. Briddell, Michael J. Hubbard.
United States Patent |
RE37,683 |
Briddell , et al. |
April 30, 2002 |
Adhesive composition and method for providing water-tight joints in
single-ply roofing membranes
Abstract
A cured adhesive tape composition for adhering together roofing
materials such as synthetic EPDM rubber and which provides long
term water tightness is provided. The adhesive composition includes
substantially equal amounts by weight of a) a rubbery polymer
comprising a blend of an ethylene-propylenediene terpolymer, a
halogenated butyl rubber or a halogenated copolymer of
p-methylstyrene and isobutylene, and polyisobutylene b) a
compatible tackifier, and c) an accelerator/cure package for the
rubbery polymer. The cured composition exhibits a peel strength of
at least 715 grams/cm at room temperature, at least 300 grams/cm at
70.degree. C., and supports a static load of at least 300 grams at
70.degree. C.
Inventors: |
Briddell; Brian J. (Jackson,
MI), Hubbard; Michael J. (Holland, OH) |
Assignee: |
Adco Products, Inc. (Raleigh,
NC)
|
Family
ID: |
46277284 |
Appl.
No.: |
09/770,036 |
Filed: |
January 26, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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637628 |
Jan 4, 1991 |
|
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Reissue of: |
792458 |
Nov 15, 1991 |
05242727 |
Sep 7, 1993 |
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Current U.S.
Class: |
428/42.2;
525/145; 525/154; 525/235; 525/236; 525/237; 525/240; 525/87;
428/355R |
Current CPC
Class: |
C09J
123/16 (20130101); C09J 123/20 (20130101); C09J
123/16 (20130101); C09J 123/20 (20130101); Y10T
428/149 (20150115); Y10T 428/2852 (20150115); C08L
2666/04 (20130101); C08L 2666/04 (20130101); C08L
2666/04 (20130101) |
Current International
Class: |
C09J
123/00 (20060101); C09J 123/16 (20060101); C09J
123/20 (20060101); C08L 023/16 (); C08L 023/22 ();
C08L 023/28 (); C08L 061/06 () |
Field of
Search: |
;428/42,355
;525/145,154,87,235,236,237,240 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Order Granting in Part Carlisle's Motion for Summary Judgment, ADCO
Products, Inc. v. Carlisle Syntec Incorporated, C.A. Case No.
99-359-RRM (U.S. District Court for the District of Delaware),
dated Aug. 11, 2000. .
Carlisle's Motion for Summary Judgment of Invalidity, ADCO
Products, Inc. v. Carlisle Syntec Incorporated, C.A. Case No.
99-359-RRM (U.S. District Court for the District of Delaware),
dated Apr. 14, 2000. .
Memorandum in Support of Carlisle's Motion for Summary Judgment of
Invalidity, ADCO Products, Inc. v. Carlisle Syntec Incorporated,
C.A. Case No. 99-359-RRM (U.S. District Court for the District of
Delaware), dated Apr. 14, 2000. .
Letter from ADCO Products, Inc. to Judge McKelvie, ADCO Products,
Inc. v. Carlisle Syntec Incorporated, C.A. Case No. 99-359-RRM
(U.S. District Court for the District of Delaware), dated Jul. 28,
2000..
|
Primary Examiner: Nutter; Nathan M.
Attorney, Agent or Firm: Banner & Witcoff, Ltd.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of U.S. application Ser.
No. 637,628, filed Jan. 4, 1991, now abandoned, the disclosure of
which is hereby incorporated by reference.
Claims
What is claimed is:
1. A cured adhesive composition for adhering together EPDM roofing
materials comprising substantially equal amounts by weight of a) a
rubbery polymer comprising a blend of an ethylene-propylene-diene
terpolymer, a halogenated butyl rubber.[.or a halogenated copolymer
of p-methylstyrene and isobutylene.]. , and polyisobutylene and b)
a compatible tackifier, said composition further comprising an
accelerator/cure package for said rubbery polymer, said composition
being fully vulcanized prior to use by heating to achieve
essentially full crosslinking of the components, said composition
having a peel strength of at least 715 grams/cm at room
temperature, at least 300 grams/cm at 70.degree. C., and supports a
static load of at least 300 grams at 70.degree. C.
2. The composition of claim 1 further including a minor portion of
carbon black.
3. The composition of claim 1 in which said tackifier is selected
from the group consisting of polybutene, a phenolic resin, and
mixtures thereof.
4. A cured adhesive composition for adhering together roofing
materials consisting essentially of: a) from about 35-45% of a
rubbery polymer, b) from about 35-45% of a compatible tackifier, c)
from about 5-9% of a plasticizer, and d) from about 1-6% of an
accelerator/cure package, the resulting composition being fully
vulcanized prior to use by heating to achieve essentially full
crosslinking of the components, said composition being cured
sufficiently to support a static load of at least 300 grams at
70.degree. C., have a peel strength of at least 715 grams/cm at
room temperature and at least 300 grams/cm at 70.degree. C.
5. The composition of claim 4 in which said rubbery polymer
comprises a blend of an ethylene-propylenediene terpolymer, a
halogenated butyl rubber, and polyisobutylene.
6. The composition of claim 4 in which said rubbery polymer
comprises a blend of an ethylene-propylenediene terpolymer, a
halogenated copolymer of p-methylstyrene and isobutylene, and
polyisobutylene.
7. The composition of claim 4 in which said tackifier is selected
from the group consisting of polybutene, a phenolic resin, and
mixtures thereof.
8. The composition of claim 4 in which said plasticizer is liquid
polyisobutylene.
9. A roofing membrane adhesive tape comprising a layer of a cured
adhesive composition in the form of a strip on a release liner,
said adhesive composition comprising substantially equal amounts by
weight of a) a rubbery polymer comprising a blend of an ethylene
propylene-diene terpolymer, a halogenated butyl rubber.[.or a
halogenated copolymer of p-methylstyrene and isobutylene.]. , and
polyisobutylene and b) a compatible tackifier, said composition
further comprising an accelerator/cure package for said rubbery
polymer, said composition having been postcured after formulation
but before use by heating to achieve essentially full crosslinking
of the components and having a peel strength of at least 715
grams/cm at room temperature, at least 300 grams/cm at 70.degree.
C., and supports a static load of at least 300 grams at 70.degree.
C.
10. The composition of claim 9 further including a minor portion of
carbon black.
11. The composition of claim 10 in which said tackifier is selected
from the group consisting of polybutene, a phenolic resin, and
mixtures thereof.
12. A roofing membrane adhesive tape comprising a layer of a cured
adhesive composition in the form of a strip on a release liner,
said adhesive composition comprising substantially equal amounts by
weight of a) a rubbery polymer comprising a blend of an
ethylenepropylene-diene terpolymer, a halogenated copolymer of
p-methylstyrene and isobutylene, and polyisobutylene and b) a
compatible tackifier, said composition further comprising an
accelerator/cure package for said rubbery polymer, said composition
having been postcured after formulation but before use and having a
peel strength of at least 715 grams/cm at room temperature, at
least 300 grams/cm at 70.degree. C., and supports a static load of
at least 300 grams at 70.degree. C..Iadd.
13. A cured adhesive composition for adhering together EPDM roofing
materials comprising substantially equal amounts by weight of a) a
rubbery polymer comprising a blend of an ethylene-propylene-diene
terpolymer, a halogenated copolymer of p-methylstyrene and
isobutylene, and polyisobutylene and b) a compatible tackifier,
said composition further comprising an accelerator/cure package for
said rubbery polymer, said composition being fully vulcanized prior
to use by heating to achieve essentially full crosslinking of the
components, said composition having a peel strength of at least 715
grams/cm at room temperature, at least 300 grams/cm at 70.degree.
C., and supports a static load of at least 300 grams at 70.degree.
C..Iaddend..Iadd.
14. The composition of claim 13, further including a minor portion
of carbon black..Iaddend..Iadd.
15. The composition of claim 13 in which said tackifier is selected
from the group consisting of polybutene, a phenolic resin, and
mixtures thereof..Iaddend..Iadd.
16. The roofing membrane adhesive tape of claim 12 wherein said
composition is postcured after formulation but before use by
heating to achieve essentially full crosslinking of the
components..Iaddend..Iadd.
17. The roofing membrane adhesive tape of claim 16 further
including a minor portion of carbon black..Iaddend..Iadd.
18. The roofing membrane adhesive tape of claim 17 in which said
tackifier is selected from the group consisting of polybutene, a
phenolic resin, and mixtures thereof..Iaddend.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a cured adhesive composition and
method for providing a water-tight seal to joints of roofing
membranes, and more particularly to an EPDM-based adhesive and
method for joining sheets of EPDM rubber roofing material
together.
Roofing materials for covering large roof areas are customarily
prepared in wide sheets for installation. Elastomeric
ethylene-propylene-nonconjugated diene terpolymer (EPDM) and
isobutylene-conjugated diene copolymer (butyl rubber) compositions
are well known in the art as roofing materials due to their barrier
properties against moisture. These sheets must be overlapped and
spliced together to form a continuous, water tight sheet which
covers a roof.
EPDM roof membranes are manufactured to industry standards which
permit only a 2% shrinkage in any dimension. Much of the shrinkage
is caused by tension when the sheet is calendared and wound on a
core and cured. As the EPDM sheet is unwound it recovers, causing
the shrinkage. The recovery or shrinkage is dependent on the amount
of stress built in during processing (calendaring and winding). If
the sheet recovers 2% in a 100 foot roll it will shrink two feet.
Seams in EPDM membranes are typically 5 inches for adhesive glues
and as narrow as 2.5 inches for tapes. After seaming is
accomplished on the roof site, ensuing shrinkage could pull the
seams apart if the tape lacks sufficient static load strength.
The first generation of tapes introduced to the industry were
uncured compositions that contained curatives. Vulcanization was
achieved only after extended exposure to high roof top
temperatures. It has been witnessed in roof curing (in situ curing)
tapes that sliding of the seam in the shear direction can occur
before there is enough time for the adhesive to cure and gain
sufficient strength to hold the rubber sheets, and thus the seam,
intact.
Besides the normal shrinkage of the EPDM membrane, large variations
in temperature can occur shortly after the roof is installed. If
the EPDM membrane is seamed during the day while the EPDM membrane
is hot, the contraction of the EPDM membrane when the temperature
falls at night could result in early seam failure before the
adhesive cures. In the spring or fall, the EPDM membrane
temperature could change as much as 38.degree. C. from night to
day. During the manufacturing of EPDM sheeting stresses are built
into the sheet as described above. When the sheet is subsequently
rolled out on a roof surface, recovery occurs resulting in
reduction in size. The amount of "shrinkage" that results
determines the stress forces applied to the bonded seams.
Close, U.S. Pat. No. 4,472,119, is an example of an uncured roofing
adhesive composition. The composition is taught to be applied as a
liquid dissolved in a solvent. Example I shows a composition which
is cured in situ for seven days after application to a roofing
membrane. However, the prior art has recognized the shortcomings of
such in situ cure adhesives. Chiu, U.S. Pat. No. 4,588,637, in the
paragraph bridging columns 1 and 2, describes the problems with
uncured adhesive tapes including low initial strengths. Metcalf,
U.S. Pat. No. 4,601,935, also describes the shortcomings of in situ
curable adhesives, including low initial strengths.
Another method used previously in the art for sealing together the
overlapping sheets of roofing material has been to position an
unvulcanized rubber tape between the overlapped portions of the
roofing membranes and then spot vulcanizing the tape by the
application of heat and pressure. However, this method required the
presence of a vulcanizing press on the job site. Further, good
adhesion required long vulcanizing times which slowed down the
installation of the roofing materials.
Yet another method of sealing the overlapping sheets together has
been the use of adhesives such as solvent-based neoprene-based
adhesives. Problems have been encountered not only with the
strength of the adhesive bonds formed at the splices, but also with
the long term durability of those bonds. For example, environmental
conditions may act to impair the quality of the bond achieved. If
conditions are windy, dust and other contaminants may become lodged
in the adhesive and impair its ability to adhere the sheets of
roofing material together. If there are high temperatures, the
adhesive may dry out too quickly. High humidity may cause moisture
condensation which interferes with good adhesion. Variations in
environmental conditions may require that the workers installing
the roof modify their procedures, complicating the
installation.
The use of brushes that leave streaks or coatings of uneven
thickness are known to reduce bond strength. Neoprene adhesives
contain solvents, usually aromatic, such as toluene, xylene, and
others. Solvents are environmentally undesirable and subject to
increasing regulation. They have toxicity and pose a health hazard.
Finally, due to their flammability, a fire hazard exists, and there
have been many instances in the industry where fires and injuries
have occurred as a result of the use of solvent-based products.
Attempts have been made in the art to develop better adhesives
which may be applied more readily and which provide a long term
capability to withstand moisture penetration. For example, Streets,
U.S. Pat. No. 4,640,730, teaches the use of a styrene-butadiene
block copolymer mixed with a hydrocarbon resin as an adhesive for
EPDM and butyl rubber-based roofing materials. Chiu, U.S. Pat. Nos.
4,588,637 and 4,855,172, teach a roofing adhesive of a cured butyl
rubber-based composition made by compounding a butyl rubber
copolymer, a curing agent for the butyl rubber, carbon black, and a
compatible tackifier.
Kakehi, U.S. Pat. No. 4,404,056, teaches a cold vulcanizable
adhesive tape having a Mooney viscosity of from 5 to 25 which
includes a rubbery polymer, a vulcanizing agent, a vulcanizing
accelerator, an adhesive agent, and a softening agent. The tape is
positioned between overlapping sheets of roofing material, and the
sheets are pressed together with a roller or the like.
However, the need still remains in the art for effective adhesive
compositions and methods of application for use in adhering
together sheets of EPDM-based roofing materials which provides not
only ease of application and good strength, but also a long term
watertight seal.
SUMMARY OF THE INVENTION
The present invention meets that need by providing a procured
adhesive composition for adhering together roofing materials such
as synthetic EPDM rubbers and which provides long term water
tightness. The adhesive is soft and initially tacky, yet possesses
high initial strength at 70.degree. F., at least in part due to the
cured nature of the composition. According to one aspect of the
present invention, the adhesive composition includes substantially
equal amounts by weight of a) a cured rubbery polymer comprising a
blend of an ethylenepropylene diene terpolymer, a halogenated butyl
rubber or a halogenated copolymer of p-methylstyrene and
isobutylene, and polyisobutylene and b) a compatible tackifier.
Preferably, the tackifier is selected from the group consisting of
polybutene, a phenolic resin, and mixtures thereof.
The composition further includes an accelerator/cure package for
the rubbery polymer. The composition exhibits a peel strength of at
least 715 grams/cm at room temperature, at least 300 grams/cm at
70.degree. C., and supports a static load of at least 300 grams at
70.degree. C., preferably for a minimum of 96 hours. The
composition may further include a minor portion of carbon black and
other conventional fillers and/or desiccants.
In a preferred form, the adhesive composition of the present
invention includes: a) from about 35-45% of a rubbery polymer
blend, b) from about 35-45% of a compatible tackifier, and c) from
about 1-6% of an accelerator/cure package. The composition is
post-cured after extrusion and before use prior to provide a fully
cured adhesive having high initial adhesivity and strength. For
convenience, the adhesive composition of the present invention may
be fabricated in the form of an extruded tape wound in a roll on a
release liner. The adhesive tapes are typically about 5.0-15.0 cm
wide and about 0.5-1.0 mm thick.
The present invention also includes a method for adhering together
sheets of synthetic rubber roofing materials which includes the
steps of applying to at least one overlapping edge of the sheets a
preformed cured pressure sensitive tape comprising substantially
equal amounts by weight of a) a rubbery polymer comprising a blend
of an ethylene-propylene-diene terpolymer, a halogenated butyl
rubber or a halogenated copolymer of p-methylstyrene and
isobutylene, and polyisobutylene and b) a compatible tackifier. The
composition further includes an accelerator/cure package for the
rubbery polymer. The adhesive composition has a peel strength of at
least 715 grams/cm at room temperature, at least 300 grams/cm at
70.degree. C., and supports a static load of at least 300 grams at
70.degree. C. For convenience, the tape is carried on a release
liner.
After application of the pressure sensitive seaming tape and
removal of the release liner, the overlapping edges of the sheets
are pressed together using firm pressure to insure good contact of
tape to the sheet material. In a preferred embodiment, the
overlapping surface of the sheets are first cleaned with a solvent
to remove any traces of grease, oil, or other contaminants which
could interfere with the formation of a water-tight seal. No primer
need be applied to the sheet surface. However, certain properly
formulated primer compositions are known to enhance bond formation
and result in higher peel strengths.
The present invention provides an adhesive tape composition which
is easy to transport and store, has a long storage life, and can be
easily applied at a job site. In use, the adhesive tape provides an
initial high adhesion and forms a strong bond and water-tight seal
between overlapping sheets of synthetic rubber roofing membrane
material. The cured adhesive tape composition is comprised of a
sufficiently high crosslink density to provide strong adhesive
bonding to the sheets of rubber roofing materials through all
widely known roof temperature extremes. The adhesive tape can be
applied in a variety of weather conditions and is stable at
elevated temperatures which may be encountered on roofs. The
composition does not embrittle at low temperatures and remains
sufficiently strong and flexible to withstand the expansion and
contraction of the roof and underlying roofing materials without
seal rupture.
Accordingly, it is an object of the present invention to provide a
cured adhesive composition for use in adhering together sheets of
EPDM-based roofing materials which provides not only case of
application and good strength, but also a long term water tight
seal. This, and other objects and advantages of the invention will
become apparent from the following detailed description and the
appended claims.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
By providing a cured adhesive composition which includes
substantially equal amounts, by weight, of a rubbery polymer blend
and a compatible tackifier, the composition of the present
invention is soft and possesses an initial high adhesivity. This
permits the formation of a strong initial bond between overlapping
layers of roofing material. Additionally, the composition possesses
high initial strength and static load resistance so that the joint
which is formed remains water tight. Static load resistance is a
measure of the adhesive composition's ability to resist expansion
and contraction of the roofing membrane while maintaining a water
tight seal. The composition may be provided as a preformed adhesive
tape which provides ease of application at a job site.
The adhesive tape composition of the present invention preferably
comprises, as the rubbery polymer component, a blend of an
ethylene-propylene-diene terpolymer, a halogenated butyl rubber or
a halogenated copolymer of p-methylstyrene and isobutylene, and
poly-isobutylene. For example, the ethylene-propylene-diene
terpolymer may be Vistalon 2200, 2504, 5600, or 6505, commercial
products available from Exxon Chemical; or Royalene 501, 502, 505,
512, or 521, commercial products available from Uniroyal; or EpSyn
2506, 40A, or 4506, commercial products available from Copolymer;
or Trilene 65 or 67, low molecular weight terpolymers commercially
available from Uniroyal. The halogenated butyl rubber may be a
compound such as Bromobutyl 2030 or X-2, or Chlorobutyl 1240 or
1255, commercial products available from Polysar; or Bromobutyl
2222 or 2244, or Chlorobutyl HT-1065, HT-1066, or HT-1068,
commercial products available from Exxon Chemical. The halogenated
copolymer of p-methylstyrene and isobutylene may be a compound such
as Bromo XP-50 commercially available from Exxon Chemical. The
halogenated p-methylstyrene/isobutylene copolymer combines the low
permeability properties of a butyl rubber with the environmental
and aging properties of in EPDM rubber.
The polyisobutylene component of the composition may be, for
example, Vistanex L-80, L-100, L-120, or L-140, commercial products
available from Exxon Chemical; or Oppanol B-50 or B-100, commercial
products available from BASF Corporation; or a low molecular weight
polyisobutylene such as LMMS or LMMH, commercial products available
from Exxon Chemical; or Oppanol B-10 or B-15, commercial products
available from BASF Corporation.
The adhesive tape composition also contains a compatible tackifier
in an amount substantially equal to the rubbery polymer. The
tackifier gives the composition its softness and high initial
adhesivity. Suitable tackifying agents include polybutene, for
example Indopol H-100, H-300, H-1500, or H-1900, commercial
products available from Amoco Chemical; or Parapol 700, 950, 1300,
2200, or 2500, commercial products available from Exxon Chemical,
phenolic resins such as Akron P-90 or P-133, commercial products
available from Akrochem; or SP-1068 or SP-1077, commercial products
available from Schnectady Chemical; or Durez 31671, a commercial
product available from Occidental Chemical; or Dyphene 8318 or
8320, commercial products available from Sherwin-Williams Company,
and mixtures thereof.
The adhesive composition also includes an accelerator/cure package
for the rubbery polymer component. The rubbery composition may be
cured using any of several well-known curing systems including
sulfur and sulfur containing systems as well as zinc oxide.
Typically, about 0.2 to about 2.0% by weight of curing agent in the
composition is sufficient. The addition of a small amount of zinc
oxide, 1-2% by weight, improves the high temperature stability of
the composition as well.
Suitable curing accelerators for use in the present invention
include sulfur, thiazoles, thiurams, and dithiocarbamates. For
example, dipentamethylene thiuram hexasulfide, tetraethyl thiuram
disulfide, tetramethyl/ethyl thiuram monosulfide, tetramethyl
thiuram disulfide, tetramethyl thiuram monosulfide,
4,4'dithiodimorpholine, 2-(morpholino-dithio)-benzothiazole, zinc
dibutyl phosphorodithiate, 2-mercaptobenzo-thiazole, benzothiazyl
disulfide, zinc mercaptobenzothiazole, zinc dibutyl
dithiocarbamate, zinc diethyl dithiocarbamate, zinc dimethyl
dithiocarbamate, copper dibenzyl dithiocarbamate or tellurium
diethyl dithiocarbamate, and mixtures thereof, commercial products
available from Akrochem, R. T. Vanderbilt, Akzo, E. I. du Pont de
Nemours and Company, Mobay, Monsanto Chemical Company, Pennwalt, or
Uniroyal Chemical. Again, only small amounts of an accelerator are
required. Typically from about 0.5 to about 2.0% by weight of
accelerator in the composition is sufficient. The composition may
further include a minor portion of carbon black and/or other
conventional fillers or desiccants such as calcium oxide
(lime).
The composition, after extruding onto a release liner, is beat
cured to cure the rubbery polymer. Typically, the composition is
heated to a temperature of about 100.degree. C. to about
125.degree. C. for a period of between about 2-6 hours to achieve
essentially full crosslinking. Temperature limits have been
established to protect the paper release liners used during cure.
However, temperatures of 149.degree. C. and above could be used if
a heat resistant liner such as a polyester (Mylar) was used,
thereby reducing the time required to obtain a proper degree of
cure.
All of the compositions of the present invention exhibit peel
strengths of at least 715 grams/cm at room temperature, at least
300 grams/cm at 70.degree. C., and support a static load of at
least 300 grams at 70.degree. C. All compositions of the present
invention provide both high initial adhesion and high initial
strength at 70.degree. C. Without the high initial strength and
adhesion, the joined, overlapped roofing materials could slip or be
deformed such that the water tightness of the joint is destroyed.
Further, because of the long term strength and flexibility,
resistance to low temperature embrittlement, and high temperature
stability of the adhesive, the joints which are formed remain water
tight.
The compositions described above are fully vulcanized to achieve
sufficient strength, adhesivity, and static load resistance. Full
vulcanization is achieved when further exposure to elevated
temperature does not change the adhesivity, strength, or static
load resistance. Complete vulcanization enhances these performance
properties. The compositions described above are blends of polymers
that contribute to the proper balance of properties through its
cure potential. Polyisobutylene rubber has no cure potential and
thus acts as a polymer diluent. Halobutyl rubber has low to
moderate cure capability due to its inherent low unsaturation level
of under 2.5%. Ethylene propylene terpolymers have unsaturation
levels as high as 10%. The cured blend must have sufficient
strength to support a static load of at least 300 grams at
70.degree. C., preferably for a minimum of 96 hours. A maximum of
6.0 mm of slippage with a 300 gram static load at 70.degree. C. is
considered acceptable performance. Excessive cure capacity in the
composition reduces adhesivity and may result in seam failure. If
the composition is not fully cured prior to application, further
curing on the roof caused by elevated roof top temperatures may
cause the tape to become too strong with accompanying loss of
adhesivity.
In order that the invention may be more readily understood,
reference is made to the following examples of compositions within
the scope of the present invention, which examples are intended to
be illustrative of the invention, but are not intended to be
limiting in scope.
EXAMPLE 1
The compositions and amounts listed below were charged to a
conventional double-arm sigma blade mixer and blended for a period
of three hours. The resulting compositions were then extruded into
an adhesive tape and cured at a temperature of 100.degree. C. to
125.degree. C. for 3 hours. The resulting compositions had a high
initial adhesivity and were measured to have the peel strengths at
room temperature and 70.degree. C. and static load resistance at
70.degree. C. reported below.
Parts by Weight (Based on 100 parts EPDM) 1 2 3 4 5 6 7 Compound
Description EPDM rubber 100 100 100 100 100 100 100 Halogenated
butyl 60 91 62 98 60 91 25 rubber Polyisobutylene 50 76 52 82 50 76
50 Antioxidant 1 1 1 1 1 1 1 Phenolic resin 44 40 28 72 44 40 27
Zinc oxide 6 9 6 9 6 9 6 Pulverized lime 6 9 6 10 6 9 6
Accelerator/ 9 9 9 15 6 14 9 Cure package Carbon Black 9 14 9 14 9
14 9 Polybutene tackifier 176 189 129 202 123 270 123 Physical
Properties Static Load 3.0 1.0 4.0 1.0 0.0 5.0 2.5 Resistance,
70.degree. C., slippage (mm) 300 gram load Peel strength, g/cm, 715
750 825 790 715 985 750 7 days at room temperature Peel strength,
g/cm, 375 350 350 375 330 300 310 7 days at 70.degree. C., pulled
at 70.degree. C.
EXAMPLE 2
A test assembly was constructed to demonstrate how dramatic changes
in rooftop temperatures can place very high stress on bonded EPDM
seams. This test assembly comprised a 30 cm.times.30 cm board
comprised of 12.7 cm plywood, two 15 cm.times.30 cm pieces of 1.1
mm thick EPDM sheeting, and clamps at each side of the board for
securing the EPDM sheet in place.
A 30 cm.times.7.5 cm overlap seam was prepared using the EPDM based
composition labeled 4 in Example 1. The joined sheet was then
conditioned for one hour at 70.degree. C. The joined sheet was then
stretched an additional 6 cm and clamped to the plywood board. This
was accomplished with the seam positioned in the middle of the
board and running parallel to the clamps.
The assembly was then conditioned at -18.degree. C. After 24 hours
the seam was examined for slippage or any sign of failure. The
assembly was then cycled 10 times as follows: 2 hours at room
temperature, followed by 2 hours at 70.degree. C., followed by 24
hours at -18.degree. C.
No evidence of failure was detected. It was concluded that the
cured tape of the present invention possessed sufficient strength
through the temperature extremes to prevent slippage and resulting
seam failure.
EXAMPLE 3
A static load test was conducted in which 5.08 cm by 2.54 cm
samples of EPDM membrane were cleaned and a 6.45 square cm area of
tape was bonded using the composition labeled 4 in Example 1,
leaving 2.54 cm tabs for clamping on each end. The assembly was
suspended in a vertical position at 70.degree. C. and a weight of
300 grams was attached. The assembly was evaluated over a period of
7 days to determine the amount of slippage. It was found that up to
300 grams in load produced no slippage.
While certain representative embodiments and details have been
shown for purposes of illustrating the invention, it will be
apparent to those skilled in the art that various changes in the
methods and apparatus disclosed herein may be made without
departing from the scope of the invention, which is defined in the
appended claims.
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