U.S. patent application number 10/082956 was filed with the patent office on 2002-09-12 for mixable room temperature castable polyurethane system.
This patent application is currently assigned to UNITED TECHNOLOGIES CORPORATION. Invention is credited to Bernat, Laurence E., Putnam, John W., Vontell, John H., Wesson, John P..
Application Number | 20020128422 10/082956 |
Document ID | / |
Family ID | 22830777 |
Filed Date | 2002-09-12 |
United States Patent
Application |
20020128422 |
Kind Code |
A1 |
Putnam, John W. ; et
al. |
September 12, 2002 |
Mixable room temperature castable polyurethane system
Abstract
The present invention relates to a polyurethane compound which
has particular utility as a potting compound for fan exit guide
vane assemblies of commercial gas turbine engines. The polyurethane
compound comprises a formulation of polyurethane prepolymers mixed
with an aromatic amine curing agent (hardener) in a volumetric mix
ratio in the range of from about 0.9:1 to about 1:1. The
polyurethane prepolymer consists of a blend of different polyethers
based on diphenylmethane diisocyanate (MDI). The amine curing agent
is a blend of oligomeric diamines with an aromatic diamine with a
catalytic component. Both of the blends, in an uncured state, are
liquid at room temperature.
Inventors: |
Putnam, John W.;
(Glastonbury, CT) ; Bernat, Laurence E.;
(Woodstock, CT) ; Wesson, John P.; (Vernon,
CT) ; Vontell, John H.; (Manchester, CT) |
Correspondence
Address: |
Barry L. Kelmachter
Bachman & LaPointe, P.C.
Suite 1201
900 Chapel Street
New Haven
CT
06510-2802
US
|
Assignee: |
UNITED TECHNOLOGIES
CORPORATION
|
Family ID: |
22830777 |
Appl. No.: |
10/082956 |
Filed: |
February 26, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10082956 |
Feb 26, 2002 |
|
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09668206 |
Sep 22, 2000 |
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09668206 |
Sep 22, 2000 |
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09222090 |
Dec 29, 1998 |
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Current U.S.
Class: |
528/61 |
Current CPC
Class: |
C08G 18/10 20130101;
C08G 18/7664 20130101; C08G 18/10 20130101; C08G 18/3237
20130101 |
Class at
Publication: |
528/61 |
International
Class: |
C08G 018/10 |
Claims
What is claimed is:
1. A polyurethane compound comprising a first component and a
second component, said first component consisting of a blend of
different polyether based MDI prepolymers, each of said polyether
prepolymers having a different diphenylmethane diisocyanate content
and said second component comprising an amine curing agent
consisting of a blend of diamines.
2. The polyurethane compound according to claim 1, wherein said
first and second components are present in a volumetric mix ratio
of the first component to the second component in the range of from
about 0.9:1 to about 1:1.
3. The polyurethane compound according to claim 1, wherein said
first and second components are present in a volumetric mix ratio
of the first component to the second component in the range of from
about 0.95:1 to about 1:1.
4. The polyurethane compound according to claim 1, wherein each of
said first and second components when in an uncured state is liquid
at room temperature.
5. The polyurethane compound according to claim 1, wherein said
first component has a NCO content in the range of from about 11.5%
to about 14.5%.
6. The polyurethane compound according to claim 5, wherein said NCO
content is in the range of from about 12% to about 14%.
7. The polyurethane compound according to claim 5, wherein said NCO
content is about 13%.
8. The polyurethane compound according to claim 1, wherein said
first component comprises a blend of a first diphenylmethane
diisocyanate component having a density of about 1.2 g/cm , an
equivalent weight of about 286 g/mol and a NCO content in the range
of from about 13.5% to about 16.5% and a second diphenylmethane
diisocyanate component having a density of about 1.06 g/cm , an
equivalent weight of about 375 g/mol, and a NCO component in the
range of from about 9.7% to about 12.7%.
9. The polyurethane compound according to claim 1, wherein said
first component has a first diphenylmethane diisocyanate component
with a NCO content in the range of from about 14% to about 16% and
a second diphenylmethane diisocyanate component with a NCO content
in the range of from about 10.2% to about 12.2%.
10. The polyurethane compound according to claim 1, wherein said
first component has a first diphenylmethane diisocyanate component
with a NCO content of about 15% and a second diphenylmethane
diisocyanate component with a NCO content of about 11.2%.
11. The polyurethane compound according to claim 1, wherein said
second component comprises a blend of two oligomer diamines having
different equivalent weights and an amine having chlorine groups
attached thereto.
12. The polyurethane compound according to claim 11, wherein said
second component has an amine to NCO stiochiometric ratio between
about 0.85:1 and about 1.05:1.
13. The polyurethane compound according to claim 12, wherein said
amine to NCO stiochiometric ratio is between about 0.9:1 and about
1:1.
14. The polyurethane compound according to claim 12, wherein said
amine to NCO stiochiometric ratio is about 0.95:1.
15. The polyurethane compound according to claim 11, wherein said
second component comprises a blend of a first oligomeric diamine
having an equivalent weight of about 235 g/mol and a density of
about 1.04 g/cm.sup.3, a second oligomeric diamine having an
equivalent weight of about 415 g/mol and a density of about 1.04
g/cm.sup.3, and a diamine having an equivalent weight of about 190
g/mol and a density of 0.95 g/cm.sup.3.
16. A polyurethane compound for potting vanes for use in a turbine
engine, said polyurethane compound comprising: a first component
comprising a blend of different polyethers based on diphenylmethane
diisocyanate; and a second component comprising a blend of
oligomeric aromatic diamines and an aromatic diamine with a
catalytic component.
17. The polyurethane compound according to claim 16, further
comprising each of said first and second components being liquid at
room temperature when in an uncured state.
18. The polyurethane compound according to claim 16, further
comprising a volumetric mix ratio of the first component to said
second component in the range of from about 0.9:1 to about 1:1.
19. The polyurethane compound according to claim 16, wherein said
first component comprises a blend of a first polyether based
diphenylmethane diisocyanate prepolymer having a first NCO content
and a second polyether based diphenylmethane diisocyanate
prepolymer having a second NCO content, which second NCO content is
different from aid first NCO content.
20. The polyurethane compound according to claim 19, wherein said
blend has a NCO content of about 13%.
21. The polyurethane compound according to claim 16, wherein said
second component comprises a blend of two oligomer diamines having
different equivalent weights and a diamine having chlorine groups
attached to it.
22. A method for making a polyurethane compound comprising:
providing a formulation of polyurethane prepolymers in liquid form
at room temperature; providing an aromatic amine curing agent in
liquid form at room temperature; and mixing said polyurethane
prepolymer formulation with said aromatic amine curing agent in a
volumetric ratio of 0.9:1 to about 1:1.
23. The method according to claim 22, wherein said step of
providing a formulation of polyurethane prepolymers comprises
providing a blend of different polyether based MDI prepolymers.
24. The method according to claim 23, wherein said step of
providing a blend of different polyether based MDI prepolymers
comprises blending a first polyether based MDI prepolymer having a
NCO content in the range of from about 13.5% to about 16.5% with a
second polyether based MDI prepolymer having a NCO content in the
range of from about 9.7% to about 12.7%.
25. The method according to claim 22, wherein said step of
providing an aromatic amine curing agent comprises providing a
blend of oligomeric diamines and an aromatic diamine with a
catalytic component.
26. The method according to claim 25, wherein said blend providing
step comprises blending two oligomeric diamines having different
equivalent weights with said aromatic diamine.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation-in-part application of U.S. patent
application Ser. No. 09/222,090, entitled A MIXABLE ROOM
TEMPERATURE CASTABLE POLYURETHANE SYSTEM, filed Dec. 29, 1998.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to an improved polyurethane
compound which has utility as a potting compound in fan exit guide
vane assemblies of commercial gas turbine engines.
[0003] Polyurethane compounds have been used as potting compounds
in fan exit guide vane assemblies of commercial gas turbine
engines. Currently available polyurethane potting materials suffer
from a number of deficiencies. For example, some are difficult to
process, resulting in high rework and/or poor yield. Others contain
hazardous materials which require special handling procedures and
which can not be used at all at many manufacturing facilities.
[0004] One polyurethane compound which has been used is one from a
company named Jonal. The compound is difficult to work with, as it
requires heating of the resin above 180 degrees Fahrenheit and
melting of the hardener above 300 degrees Fahrenheit, before
mixing. The combining of the two heated components is done by
weight and a hand measured mark on the delivery system cartridge,
which introduces mix variations. Once combined, the system has a
working life of eight minutes. The hand mixing introduces another
variable into the system along with entrapped air that cannot be
removed in the short work-life time. The entrapped air bubbles are
cause for vane assembly rejection/rework.
[0005] Thus, there remains a need for a polyurethane compound which
has improved quality, manufacturing properties and adhesive
strength.
[0006] It is the aim of the present invention to provide a
polyurethane compound which fulfills this need.
SUMMARY OF THE INVENTION
[0007] Accordingly, it is an object of the present invention to
provide a polyurethane compound which has improved quality,
manufacturing properties and adhesive strength.
[0008] It is a further object of the present invention to provide a
polyurethane compound as above which has utility as a potting
compound in fan exit guide vane assemblies of commercial gas
turbine engines.
[0009] It is a further object of the present invention to provide a
polyurethane compound as above which can be mixed in manufacturing
friendly automated equipment.
[0010] It is yet a further object of the present invention to
provide a polyurethane compound as above which can be packaged
without the introduction of air.
[0011] The polyurethane compound of the present invention meets the
foregoing objects.
[0012] In accordance with the present invention, a polyurethane
compound or system is provided which contains a formulation of
polyurethane prepolymers mixed with an aromatic amine curing agent
in a volumetric mix ratio of from about 0.9:1 to about 1:1. The
formulation of polyurethane prepolymers consists of a blend of
different polyethers based on diphenylmethane diisocyanate. The
aromatic amine curing agent preferably comprises a blend of
oligomeric diamines and an aromatic diamine with a catalytic
component. Both of the blends, when in an uncured state, are liquid
at room temperature. Polyether type prepolymers are important for
moisture and solvent resistance. Polyurethane based MDI prepolymers
are important for health and safety reasons, for being liquid at
room temperature, and for offering better adhesion properties.
Aromatic amine curing is important for best thermal stability and
moisture resistance.
[0013] Other details of the polyurethane compound of the present
invention, as well as other objects and advantages attendant
thereto, are set forth in the following detailed description.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0014] In accordance with the present invention, a preferred
polyurethane compound is formed by mixing a formulation of
polyurethane prepolymers with an aromatic amine curing agent in a
volumetric mix ratio of about 0.9:1 to an about 1:1, preferably
from about 0.95:1 to about 1:1.
[0015] The polyurethane prepolymer formulation in accordance with
the present invention consists of a blend of different polyethers
based on diphenylmethane diisocyanate (MDI), which blend has an NCO
content in the range of about 11.5% to about 14.5%, preferably from
about 12% to 14%, and most preferably about 13%. As used herein,
the term NCO content means the grams of NCO per gram of
prepolymer.
[0016] A polyether based MDI prepolymer to be used in the present
invention should have a structure as follows: 1
[0017] where x.gtoreq.1 and n has a repeat value of 0 to 4,
preferably 1 to 2.
[0018] There are any number of commercially available materials
that meet the foregoing structure. Suitable polyether based MDI
prepolymers include Versathane SME-75A, Versathane SME-80A,
Versathane SME-90A, Versathane SME-95A, and QG 162 (all
manufactured by Air Products Corporation), Rubinate 9009 and
Rubinate 1027 (both produced by ICI), Vibrathane B-625, Vibrathane
B-635, Vibrathane B-670 and Vibrathane B-836 (all produced by
Uniroyal), and Andur M-10.
[0019] The different polyethers which are used to form the blend
preferably comprise two types of diphenylmethane diisocyanates. The
first type of polyether has a NCO content in the range of from
about 13.5% to about 16.5%, preferably in the range of from about
14% to about 16%, and most preferably about 15%, a density of about
1.2 g/cm.sup.3, and an equivalent weight of about 286 g/mol.
Equivalent weight is the molecular weight divided by the number of
reactive sites or equivalents on the prepolymer. One such material
which may be used for the first type of polyether is Andur M-10.
The second type of polyether has a NCO content in the range of from
about 9.7% to about 12.7%, preferably from about 10.2% to about
12.2%, and most preferably about 11.2%, a density of about 1.06
g/cm.sup.3, and an equivalent weight of about 375 g/mol. One such
suitable material which may be used for the second type of
polyether is Vibrathane B-670.
[0020] The polyurethane prepolymer formulation is prepared by
combining the two polyether types at room temperature, stirring
them to obtain a homogeneous solution, de-aerating at room
temperature, and handling using standard dry conditions for
moisture sensitive urethanes. The two polyethers are mixed in
volumetric amounts sufficient to provide the resulting blend with a
NCO content in the range of about 11.5% to about 14.5%, preferably
about 12% to 14% and most preferably about 13%. When using the
aforementioned representative materials, 61.6 g of Andur M-10 may
be mixed with 68.4 g of Vibrathane B-670 to form a useful polyether
blend.
[0021] The aromatic amine curing agent (hardener) is formed from
two oligomeric aromatic diamines (that is, polyether polymers
terminated with aromatic amines) and a third aromatic diamine. The
oligomeric aromatic diamines used in the present invention have a
structure such as: 2
[0022] Suitable aromatic amines which may be used in the present
invention include Versalink P-250, Versalink P-650, Versalink
P-1000, Polacure 740M and Lonzacure MCDEA (all manufactured by Air
Products) and Unilink 4100 and Unilink 4200 (both manufactured by
UOP). The desired amine to NCO Stiochiometric ratio is between
about 0.85:1 and about 1.05:1, preferably from about 0.9:1 to about
1:1, and ideally about 0.95:1.
[0023] The first of the oligomeric diamines to be used to form the
curing agent preferably has a density of about 1.04 g/cm.sup.3 and
an equivalent weight of about 235 g/mol. A suitable oligomeric
diamine which can be used for the first oligomeric diamine is
Versalink P250. The second of the oligomeric diamines to be used to
form the curing agent preferably has a density of about 1.04
g/cm.sup.3 and an equivalent weight of about 415 g/mol. Versalink
P250 has an average repeat value of n=3.5. A suitable oligomeric
diamine which can be used for the second oligomeric diamine is
Versalink P650. Versalink P650 has an average repeat value of
n=9.5. The third aromatic diamine to be used to form the curing
agent is preferably characterized by chlorine groups attached to it
and has a density of about 0.95 g/cm.sup.3 and an equivalent weight
of about 190 g/mol. The chemical structure for this aromatic
diamine is: 3
[0024] A suitable material for use as the third amine is Lonzacure
MCDEA. When the aforesaid materials are used to form the curing
agent blend, they may be present in the ratio of 75.2g of Versalink
P650 to 31.0 g of Versalink P250 to 13.1 g of Lonzacure MCDEA.
[0025] The aromatic amine curing agent preferably is formed by
heating the second oligomeric diamine (Versalink P250) to a
temperature of 180.degree. F. to melt the semisolid. This
temperature may be lowered to accommodate different types of ovens;
however, lower temperatures require longer times. The third amine
(Lonzacure) is added and the mixture is heated at 180.degree. F.
until the third amine is completely dissolved. This temperature may
be lowered to accommodate certain ovens if needed. The first
oligomeric diamine material is then added and heated at 180.degree.
F. until completely dissolved. This temperature may be lowered to
accommodate drum heater limitations. The mixture is then cooled to
room temperature and used for packaging. At room temperature, the
mixture is a flowing liquid.
[0026] As previously mentioned, the polyurethane prepolymer blend
and the aromatic amine curing agent, when in an uncured state, are
both liquid at room temperature. This allows them to be packaged in
cartridges without the introduction of air into the cartridges.
This greatly reduces the number of voids in the final part and
leads to the production of higher quality parts. The fact that both
components are liquid also allows them to be mixed in a
manufacturing friendly automated equipment. To form the final
polyurethane compound, the blended polyurethane prepolymer and the
blended amine curing agent can be passed through a mixing nozzle,
such as a motionless mixing nozzle, in a volumetric mix ratio of
blended polyurethane prepolymer to amine curing agent in the range
of from about 0.9:1 to about 1:1, preferably from about 0.95:1 to
about 1:1.
[0027] It has been found that the polyurethane compound formed by
the blended components possess many admirable qualities. For
example, the polyurethane compound of the present invention has
extremely high adhesive strength to aluminum, titanium,
polyetherimide, epoxy/graphite composites and other aerospace
materials. The polyurethane compound also has good damping
characteristics for gas turbine engine applications such as vane
potting. Still further, the polyurethane compound of the present
invention has good heat resistance up to 250.degree. F. and is
resistant to most gas turbine engine fluids. The polyurethane
compound of the present invention is also castable into any desired
shape.
[0028] To pot a vane assembly, such as a fan exit guide vane
assembly, the vane assembly is placed in a trench in a support
structure. The polyurethane compound is then introduced into the
trench at room temperature by causing the two blended components of
the compound in liquid form to pass through a mixing nozzle and
exit the nozzle into the trench. Heat is then applied to cure the
polyurethane compound. As can be seen from the foregoing
description, a potting process using the polyurethane compound of
the present invention is relatively simple to carry out.
EXAMPLE I
[0029] To illustrate the improvements created by the polyurethane
compound of the present invention, the following example was
performed. A formulation of polyurethane prepolymers and a
formulation of aromatic amine curing agent in accordance with the
present invention were prepared. The polyurethane prepolymer
formulation and the aromatic amine curing agent formulation were
mixed in a 1:1 ratio and injected through a mixing nozzle at room
temperature into a trench in a support structure holding a trial
vane. Eleven trial vanes were potted with this polyurethane
compound system. Examination of these vanes showed that there was a
very low level to no indication of entrapped air. Further, these
parts successfully met dimensional and pull test requirements and
the polyurethane compounds met or exceeded all requirements as
shown in Table 1.
1TABLE 1 PWA 597 Specification Test PWA 597 Requirement P&W
Formulation As received material Tensile Strength (psi) 4000 Min.
4230 Elongation (%) 400 Min. 440 Ten. Strength @ 100% El. 700 1760
Hardness shore A 85-95 92-93 Tear Resistance Lb./In. 200 629 Dry
heat resistance 257.degree. F./70 hours Tensile Strength reduction
25% Max. 2% Elongation reduction 10% Max. 19% increase Hardness
increase 0-10 1 Bend Flat no cracks pass Fuel resistance ASTM ref.
Fuel B (77.degree. F./22 hours) Hardness reduction -10 -4 Volume
change % 0-35 16.6 Bend Flat no cracks pass Oil Resistance SAE
Ester test fluid #2 (257.degree. F./22 hours) Hardness reduction
-10 -4 Volume change % 0-30 22.7 Bend Flat no cracks pass Hot Water
(212.degree. F./5 hours) Hardness increase 5 Max. -10 Volume change
% 0-15 4.2 Bend Flat no cracks pass Low Temperature (-60.degree.
F./5 hours) Bend Flat no cracks pass Compression Set (25%
compression 203.degree. F./22 hours) <75% of compression 36
[0030] In addition, thermal and humidity durability exposure tests
of the thus formed polyurethane compound as compared to the prior
Jonal potting compound were carried out. The 250.degree. F./500
hour exposure indicated the polyurethane compound in accordance
with the present invention had superior tensile properties at both
the room and 250.degree. F. test temperatures. The 140.degree.
F./95%RH/15 & 21 day exposure indicated that the polyurethane
compound of the present invention had a debit in tensile strength
compared to the Jonal material at both room and 250.degree. F. test
temperatures. With both exposures and test temperatures, the
polyurethane compound of the present invention maintained good
elongation properties. The Jonal material from both exposures at
the 250.degree. F. test temperature showed a significant drop in
elongation.
[0031] Durability average test results of tensile strength (psi)
and elongation (%) respectively are shown below in Table 2.
2TABLE 2 Durability Comparison Baseline tensile: P&W
Formulation = 4230 psi Material Test Temp. 25.degree. F./500
Exposed RH Exposed 15 days P&W Formulation RT 1733 4700 Jonal
RT 2192 2100 RH Exposed 21 days P&W Formulation 250.degree. F.
443 992 Jonal 250.degree. F. 796 599 Baseline elongation: P&W
Formulation = 440% Material Test Temp. 25.degree. F./500 Exposed RH
Exposed 15 days P&W Formulation RT 445 534 Jonal RT 444 573 RH
Exposed 21 days P&W Formulation 250.degree. F. 500 531 Jonal
250.degree. F. 196 159
[0032] The fan exit guide vane part prints require that vane
assembly meet a minimum 1500 pound force pull on the end caps. Six
vane assemblies were tested with the polyurethane compound in
accordance with the present invention with the results ranging from
2550 to 3200 pounds force and averaging 2800 pounds force. The
monthly vane pull test with the Jonal supplied polyurethane potting
material had a range of 1500 to 2400 pounds.
EXAMPLE 2
[0033] In addition to the above example, a test was conducted using
a polyurethane compound prepared in accordance with the present
invention. The formulation was tested on 4 vane assemblies with 1
vane humidity exposed and 1 vane thermally exposed at 140.degree.
F./95%RH/14.5 days and 250.degree. F./14.5 days respectively. These
vanes tested at 1900 pounds and 3500 pounds. The 2 baseline vanes
tested at 2600 and 2700 pounds.
[0034] The FEGVs (Fan Exit Guide Vanes) used for the above tests
all passed visual and dimensional requirements of the potting
operation.
[0035] It is apparent that there has been provided in accordance
with the present invention a mixable room temperature castable
polyurethane system which fully satisfies the means, objects, and
advantages set forth hereinbefore. While the present invention has
been described in combination with specific embodiments thereof, it
is evident that many alternatives, modifications and variations
will be apparent to those skilled in the art in light of the
foregoing description. Accordingly, it is intended to embrace all
such alternatives, modifications, and variations as fall within the
spirit and broad scope of the appended claims.
* * * * *