U.S. patent application number 16/088551 was filed with the patent office on 2021-05-13 for silane containing high modulus urethane adhesives.
The applicant listed for this patent is Dow Global Technologies LLC. Invention is credited to Matthew B. Feldpausch, Andrew R. Kneisel, Susan P. Sevidal, Daniel P. Sophiea, Huide D. Zhu.
Application Number | 20210139756 16/088551 |
Document ID | / |
Family ID | 1000005358467 |
Filed Date | 2021-05-13 |
United States Patent
Application |
20210139756 |
Kind Code |
A1 |
Zhu; Huide D. ; et
al. |
May 13, 2021 |
SILANE CONTAINING HIGH MODULUS URETHANE ADHESIVES
Abstract
Moisture-curable, one component adhesives contain an
isocyanate-terminated prepolymer, a low molecular weight
polyisocyanate compound, a hydrolysable mercaptosilane, a urethane
catalyst and a carbon black filler. The adhesives exhibit an
excellent combination of high modulus, excellent hydrolytic and
heat stability, and high sag resistance.
Inventors: |
Zhu; Huide D.; (Rochester,
MI) ; Sophiea; Daniel P.; (Lake Orion, MI) ;
Kneisel; Andrew R.; (Clarkston, MI) ; Feldpausch;
Matthew B.; (Waterford, MI) ; Sevidal; Susan P.;
(Sterling Heights, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Dow Global Technologies LLC |
Midland |
MI |
US |
|
|
Family ID: |
1000005358467 |
Appl. No.: |
16/088551 |
Filed: |
January 4, 2017 |
PCT Filed: |
January 4, 2017 |
PCT NO: |
PCT/US17/12165 |
371 Date: |
September 26, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62328048 |
Apr 27, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C09J 11/04 20130101;
C09J 2301/312 20200801; C09J 11/06 20130101; C09J 175/04 20130101;
C08K 3/04 20130101; C08K 5/5415 20130101 |
International
Class: |
C09J 175/04 20060101
C09J175/04; C09J 11/06 20060101 C09J011/06; C09J 11/04 20060101
C09J011/04 |
Claims
1. An adhesive composition comprising urethane prepolymer resin, a
reactive silane, a polyisocyanate with functionality more than 2,
one or more catalysts for isocyanate reaction with hydroxyl groups;
and carbon black filler.
2. The adhesive composition according to claim 1 wherein the
reactive silane is mercaptosilane.
3. A method of making an adhesive composition wherein a reactive
silane is separately added to the composition during the mixing of
various components of the composition.
4. The method of claim 3 where in the reactive silane is
mercaptosilane.
5. An adhesive composition made from claim 3.
6. A moisture-curable adhesive composition comprising: a) an
isocyanate-terminated prepolymer having free isocyanate groups and
an isocyanate equivalent weight of 840 to 5,000; b) 0.1 to 6 parts
by weight, per 100 parts by weight of the adhesive composition, of
at least one polyisocyanate compound having an isocyanate
equivalent weight of up to 300, the at least one polyisocyanate
compound having a number average isocyanate functionality of at
least 2.5; c) 0.1 to 4 parts by weight per 100 parts of the
adhesive composition of at least one hydrolysable organosilane, the
at least one hydrolysable organosilane including a mercaptosilane
having one mercapto group and at least one hydrolysable silane
group; d) at least one urethane catalyst and e) a carbon black
filler.
7. The adhesive composition of claim 6 wherein the mercaptosilane
includes at least one mercaptoalkyl(trialkoxy)silane or
mercaptoalkylmethyl(dialkoxy)silane.
8. The adhesive composition of claim 6 wherein the carbon black has
an oil absorption number of at least 80 cubic centimeters of
dibutyl phthalate per 100 g of the carbon black, as measured
according to ASTM D-2414-09.
9. The adhesive composition of claim 6, wherein the isocyanate
terminated prepolymer includes at least one reaction product of a
polyether diol and a diisocyanate.
10. The adhesive composition of claim 6, wherein the
isocyanate-terminated prepolymer includes at least one reaction
product of a polyester diol having a melting temperature of 40 to
85.degree. C. and a diisocyanate.
11. The adhesive composition of claim 6, which further includes a
plasticizer.
12. The adhesive composition of claim 6, which exhibits a press
flow viscosity of 5 to 200 seconds at 23.degree. C.
13. A method of making an adhesive composition according to claim
6, comprising the steps of: A) forming the isocyanate-terminated
prepolymer; B) mixing the isocyanate-terminated prepolymer with the
at least one hydrolysable silane, and then C) combining the at
least one polyisocyanate compound having an isocyanate equivalent
weight of up to 210, urethane catalyst and carbon black with the
mixture of the isocyanate-terminated prepolymer with the at least
one hydrolysable silane.
14. A method of making an adhesive composition according to claim
6, comprising the steps of: A) forming the isocyanate-terminated
prepolymer; B) mixing the isocyanate-terminated prepolymer with the
at least one polyisocyanate compound having an isocyanate
equivalent weight of up to 210; and then C) combining the at least
one hydrolysable silane, urethane catalyst and carbon black with
the mixture of the isocyanate-terminated prepolymer with the at
least one hydrolysable silane.
Description
[0001] This invention relates to a new silane containing high
modulus urethane adhesive composition. This invention also relates
to a novel method of making such high modulus urethane adhesive
composition.
[0002] Urethane adhesive compositions find applications in many
industries. For the transportation industry, urethane adhesive
compositions are used to bond glass objects such as a windshield or
a backlight window into the car body structure. In order to provide
adequate rigidity and thus better NVH performance to the car, it is
desirable to use a urethane adhesive composition with a high
modulus property after the composition is cured in place. In
addition to the high modulus characteristics, it is also desirable
that such urethane adhesive composition is usable and pumpable at
room temperature without any or much additional heating.
Furthermore, it is also desirable that the urethane adhesive can
bond to the glass frit with great hydrolytic and heat
stability.
[0003] Currently, high modulus urethane adhesive compositions can
be achieved through the use of rigid polymer resins i.e., acrylic
resins and/or crystalline polyester resins. These current existing
compositions typically have high viscosities and most likely need
heating during manufacturing and application.
[0004] The present invention provides a novel adhesive composition
that exhibits similar or higher modulus and elongation when silanes
are introduced in the mixer rather than introduced during the
prepolymer resin synthesis. It is surprising to find that the
adhesive composition containing mercaptosilane has superior
performance in sag resistance. Further, it is surprising to find
that a high modulus urethane adhesive composition is achieved with
great hydrolytic and heat stability of glass adhesion when the
adhesive composition is made in the presence of a
mercaptosilane.
[0005] The adhesive composition of the present invention in one
aspect comprises urethane prepolymer resin, a reactive silane, a
polyisocyanate with functionality more than 2, one or more
catalysts for the reaction of an isocyanate with a hydroxyl group;
and a carbon black filler.
[0006] The adhesive composition of any of the foregoing aspects of
the invention is dispensable at room temperature without any or
much heating, exhibiting high modulus properties and sag resistance
and having durable adhesion of great hydrolytic and heat
stability.
[0007] In a particular aspect, the invention is a moisture-curable
adhesive composition comprising:
[0008] a) an isocyanate-terminated, prepolymer having free
isocyanate groups and an isocyanate equivalent weight of 840 to
5,000;
[0009] b) 0.1 to 6 parts by weight, per 100 parts by weight of the
adhesive composition, of at least one polyisocyanate compound
having an isocyanate equivalent weight of up to 300, the at least
one polyisocyanate compound having a number average isocyanate
functionality of at least 2.5;
[0010] c) 0.1 to 4 parts by weight per 100 parts of the adhesive
composition of at least one hydrolysable organosilane, the at least
one hydrolysable organosilane including a mercaptosilane having one
mercapto group and at least one hydrolysable silane group;
[0011] d) at least one urethane catalyst and
[0012] e) a carbon black filler.
[0013] The invention is also a method of making the adhesive
composition of the invention, comprising the steps of:
[0014] A) forming the isocyanate-terminated prepolymer;
[0015] B) mixing the isocyanate-terminated prepolymer with the at
least one hydrolysable silane, and then
[0016] C) combining the at least one polyisocyanate compound having
an isocyanate equivalent weight of up to 300, urethane catalyst and
carbon black with the mixture of the isocyanate-terminated
prepolymer with the at least one hydrolysable silane.
[0017] The invention is also a method of making the adhesive
composition of the invention, comprising the steps of:
[0018] A) forming the isocyanate-terminated prepolymer;
[0019] B) mixing the isocyanate-terminated prepolymer with the at
least one polyisocyanate compound having an isocyanate equivalent
weight of up to 300; and then
[0020] C) combining the at least one hydrolysable silane, urethane
catalyst and carbon black with the mixture of the
isocyanate-terminated prepolymer with the at least one hydrolysable
silane.
[0021] In another aspect, the invention is a method for bonding two
or more substrates together which comprises contacting a
moisture-curable adhesive composition according to the invention
with one or more of the substrates and contacting the two or more
substrates with the adhesive composition disposed at a bond line
between the substrates and thereafter allowing the composition to
cure to form an adhesive layer bonded to the substrates at the bond
line.
[0022] The prepolymer has an isocyanate equivalent weight of at
least 840, which corresponds to an NCO content of 5% by weight. The
isocyanate equivalent weight of the prepolymer may be at least 1050
(NCO content 4%), at least 1400 (NCO content 3%) or at least 1680
(NCO content 2.5%), and may be up to, for example, 10,000 (NCO
content 0.42%), up to 8400 (NCO content 0.5%), up to 7000 (NCO
content 0.6%) or up to 5000 (NCO content 0.84%). Prepolymer
equivalent and molecular weights are determined according to the
procedure disclosed in U.S. Pat. No. 5,922,809 at column 12, lines
50 to 64, incorporated herein by reference.
[0023] The prepolymer is a reaction product of at least one polyol
with at least one polyisocyanate having an isocyanate equivalent
weight of up to 250. The polyol or mixture of polyols (when used)
preferably has a hydroxyl equivalent weight of at least 200
(equivalent to a hydroxyl number of 280). The hydroxyl equivalent
weight may be at least 500 (OH number=112), at least 800 (OH
number=70) or at least 1000 (OH number 56), and may be up to 4750
(OH number 11.8), up to 3000 (OH number 18.7), up to 2500 (OH
number 22.4). Polyol equivalent weights are determined by titration
methods. Equivalent weights for polyol mixtures are determined by
titrating the mixture, or by titrating the individual components
and determining a number average. If a mixture of polyols is used,
it is preferred that at least one component of the mixture has a
hydroxyl equivalent weight from 500 to 3000, especially from 800 to
2000.
[0024] The polyol or mixture of polyols (when used) has a number
average nominal hydroxyl functionality of at least 1.5 or at least
1.8. The hydroxyl functionality may be at least 2.0 or at least
2.2, and may be up to 4, up to 3.5, up to 3.0 or up to 2.7.
"Nominal" functionality of a polyol is the calculated number of
hydroxyl groups per molecule based on the starting materials used
in producing the polyol. In the case of polyether polyols, the
nominal functionality is the average number of hydroxyl groups per
molecule of the initiator compound or compounds used in making the
polyether polyol. As is well known, the actual functionality of
polyether polyols tends to be somewhat lower than the nominal
functionality due to side-reactions that occur during the
polymerization of alkylene oxides.
[0025] In a preferred embodiment, the polyol is a polymer mixture
that includes at least one nominally difunctional polyol and at
least one nominally trifunctional polyol. Such a mixture may have
an average hydroxyl functionality of 2.2 to 2.7.
[0026] Polyols useful to prepare the prepolymer include those
disclosed in Wu, U.S. Pat. No. 6,512,033 at column 4, line 10 to
line 64, incorporated herein by reference. Among these are, for
example, polyether polyols, polyester polyols, poly(alkylene
carbonate) polyols, hydroxyl containing polythioethers, polymer
polyols (dispersions of polymer particles in any of the foregoing
polyols) and mixtures of any two or more thereof.
[0027] Polyether polyols are a preferred type. The polyether polyol
may be, for example, a polymer or copolymer of tetrahydrofuran,
and/or one or more alkylene oxides such as ethylene oxide,
1,2-propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, and
mixtures of any two or more thereof. An especially preferred
polyether polyol is a homopolymer of 1,2-propylene oxide, a random
copolymer of at least 50% by weight 1,2-propylene oxide and
ethylene oxide, or a block copolymer of 1,2-propylene oxide and
ethylene oxide. These polyether polyols may have be capped with
ethylene oxide to produce more reactive primary hydroxyl
groups.
[0028] The polyisocyanate used to make the prepolymer is one or
more compounds having 2 or more isocyanate groups and an isocyanate
equivalent weight of up to 300, preferably 75 to 250. This
polyisocyanate preferably has an average isocyanate functionality
of 2 to 4, more preferably 2 to 3.5, still more preferably 2 to 2.5
and even more preferably 2 to 2.2. The polyisocyanate may be an
aliphatic, cycloaliphatic, araliphatic, heterocyclic or aromatic
polyisocyanate, or a mixture of any two or more thereof. Aromatic
polyisocyanates are especially preferred for making the prepolymer.
A mixture of at least one aromatic polyisocyanate and a minor
amount (such as up to 20 weight percent based on the total weight
of the polyisocyanates used to make the prepolymer) can be
used.
[0029] Examples of aromatic polyisocyanates include diphenylmethane
diisocyanate (MDI) and polymethylene polyphenylisocyanates,
polymeric MDI (PMDI, a mixture of diphenylmethane diisocyanate and
polymethylene polyphenylisocyanates), tetramethylxylene
diisocyanate and toluene diisocyanate, any of which may be modified
to include biuret, allophonate, urea, carbamate, isocyanurate or
carbodiimide groups.
[0030] Examples of aliphatic polyisocyanates include isophorone
diisocyanate, 1,6-hexamethylene diisocyanate,
bis(4-isocyanatocylohexyl))methane (H.sub.12MDI) and trimethyl
hexamethylene diisocyanate, any of which may be modified to include
biuret, allophonate, urea, carbamate, isocyanurate or carbodiimide
groups.
[0031] The prepolymer is prepared by reacting the polyol(s) with
the polyisocyanate, at proportions that provide more than 1
equivalent, preferably 1.5 to 2.5 or 1.5 to 2.1 equivalents, of
isocyanate groups per equivalent of hydroxyl group, and reacting
the mixture until the hydroxyl groups have become consumed. The
prepolymer may be prepared by any suitable method, such as bulk
polymerization and solution polymerization. The reaction preferably
carried out under anhydrous conditions, preferably under an inert
atmosphere such as a nitrogen blanket. The reaction is preferably
carried out at a temperature between about 0.degree. C. and about
150.degree. C., more preferably between about 25.degree. C. and
about 90.degree. C. The reaction is generally performed until the
residual isocyanate content reaches a constant value, indicating
that all hydroxyl groups have been consumed. The reactions may be
carried out in the presence of a urethane catalyst such as is
described below.
[0032] The prepolymer may be prepared in the presence of a
plasticizer as described below. In some embodiments, the amount of
plasticizer present during the preparation of the prepolymer is
selected so that the resulting mixture of prepolymer and
plasticizer has a desirable viscosity. Preferably, the resulting
mixture of prepolymer and plasticizer has a Brookfield viscosity of
at least 6,000 centipoises or at least about 8,000 centipoises, and
as much as 30,000 centipoises or as much as 20,000 centipoises.
Brookfield viscosity is measured on a Model DV-E Brookfield
Viscometer or equivalent, with a RV spindle #5 at a speed of 5
revolutions per second and at a temperature of 25.degree. C.
[0033] The prepolymer constitutes at least 30%, at least 35%, at
least 40%, at least 50% or at least 55% percent of the total weight
of the adhesive composition. It may constitute up to 95%, up to
90%, up to 75% or up to 70% of the total weight of the adhesive
composition.
[0034] In some embodiments, at least a portion of the
isocyanate-terminated prepolymer is a polyester-containing
prepolymer prepared in a reaction of an excess of polyisocyanate
with one or more polyester polyols which are solid at room
temperature. Preferably, the polyester polyols have melting points
of about 40.degree. C. or greater, about 45.degree. C. or greater
and most preferably about 50.degree. C. or greater, up to about
85.degree. C. and more preferably up to about 70.degree. C.
Preferably, the polyester-containing prepolymer constitutes at
least about 0.5% by weight or at least about 1% of the weight of
the adhesive composition, and may constitute, for example, up to
about 5% or up to about 3% by weight of the weight of the adhesive
composition. Preferred polyester polyols are prepared from linear
diacids and linear diols. A more preferred diacid is adipic acid.
More preferred diols are the C2 to C6 diols, such as butane diols,
pentane diols and hexane diols. Preferred polyester polyols are
available from Evonik under the trade name Dynacoll.TM. and the
designations 7360, 7330, and 7381. The polyester polyol based
isocyanate prepolymer can be prepared using the processes and
isocyanates described hereinbefore.
[0035] The adhesive composition of the invention further comprises
0.1 to 6 parts by weight of at least one polyisocyanate compound
having an isocyanate equivalent weight of up to 300, per 100 parts
by weight of the adhesive composition. This additional
polyisocyanate has an isocyanate functionality of at least 2.5,
preferably at least 2.7, more preferably at least 2.9. The
isocyanate functionality may be, for example, up to 4 or up to 3.5.
Average isocyanate functionality is determined according to U.S.
Pat. No. 5,922,809 at column 12, line 65 to column 13, line 26,
incorporated herein by reference.
[0036] Preferred additional polyisocyanates include polymeric MDI,
polymethylene polyphenylisocyanates, trimerized aromatic and/or
aliphatic polyisocyanates such as partially or fully trimerized
MDI, partially or fully trimerized toluene diisocyanate and
partially or fully trimerized 1, 6-hexamethylene diisocyanate. At
least a portion of the additional polyisocyanate preferably is an
aliphatic polyisocyanate. The additional polyisocyanate may be, for
example, a partially or fully trimerized 1, 6-hexamethylene
diisocyanate or a mixture thereof with an aromatic polyisocyanate
such as a polymethylene polyphenylisocyanate or PMDI.
[0037] The adhesive composition of the invention further comprises
at least one hydrolysable mercaptosilane. The mercaptosilane is
characterized as having one, preferably exactly one, mercapto group
and at least one, preferably 1 to 3 and more preferably 1 to 2,
hydrolysable silane groups.
[0038] A hydrolysable silane group is a group containing a silicon
atom and at least one hydrolysable substituent bonded to the
silicon atom. The hydrolysable silane group may contain 1, 2 or 3
hydrolysable substituents. The silicon atom is bonded to the
remainder of the compound (and in particular to the mercapto group)
through a non-hydrolysable linkage.
[0039] A hydrolysable substituent is one that reacts with water to
eliminate the substituent and produce a silanol moiety, --Si--OH,
which can further react to form a siloxane linkage (--Si--O--Si--).
Hydrolysable substituents include halogen, particularly chlorine;
alkoxy groups, particularly C.sub.1-6 alkoxy and especially methoxy
and ethoxy; phenoxy or ring-substituted phenoxy groups, acyloxy
groups such as acetoxy; trialkyl siloxy groups, which may be
substituted on one or more of the alkyl groups, such as trimethyl
siloxy and triethyl siloxy; triphenyl siloxy, which may be
substituted on one or more of the phenyl rings; alkenyloxy groups
such as isopropenyloxy; and ketoximato groups such as
dimethylketoximato, diethylketoximato, dicyclohexylketoximato, and
methylethylketoximato.
[0040] Examples of hydrolysable silane groups include
trichlorosilyl, methyldichlorosilyl, dimethylchlorosilyl,
phenyldichlorosilyl, (trimethylsiloxy)dimethylsilyl,
trimethoxysilyl, triethoxysilyl, methyldiethoxysilyl,
methyldimethoxysilyl, dimethylmethoxysilyl, diethylmethoxysilyl,
phenyldimethoxysilyl, trimethylsiloxymethylmethoxylsilyl,
trimethylsiloxydiethoxysilyl, methyldiacetoxysilyl,
phenydiaectoxysilyl, triacetoxysilyl,
trimethylsiloxymethylacetoxysilyl, trimethylsiloxydiacetoxysilyl,
bis(dimethylketoximato)methylsilyl,
bis(cyclohexylketoximato)methylsilyl,
bis(diethylketoximato)trimethylsiloxysilyl,
bis(methylethylketoximato)methylsilyl, tris(acetoximato)silyl, and
methylisopropyenyloxysilyl. A preferred hydrolysable silane group
is a trialkoxysilyl group such as trimethoxysilyl and
triethoxysilyl.
[0041] An especially preferred mercaptosilane is a
mercaptoalkyl(trialkoxy)silane or
mercaptoalkylmethyl(dialkoxy)silane such as gamma-mercaptopropyl
tri(methoxy)silane or
gamma-mercaptopropylmethyl(dimethoxy)silane.
[0042] The adhesive contains 0.1 to 4 parts by weight of the
mercaptosilane per 100 parts weight of the adhesive composition.
The mercaptosilane may constitute, for example, preferably at least
0.2 percent, at least 0.3 percent or at least 0.5 percent by weight
of the adhesive composition. The mercaptosilane may constitute up
to 3.0 percent, up to 2.0 percent or up to 1.5 percent of the
weight of the adhesive composition.
[0043] The adhesive composition of the invention may further
comprise one or more additional hydrolysable organosilanes that do
not contain mercapto groups, such as one or more epoxysilanes,
acrylic silanes, isocyanatosilanes and other hydrolysable silanes
containing at least one hydrolysable silane group. The hydrolysable
organosilanes as those disclosed in Mahdi, U.S. Patent Publication
2002/0100550 paragraphs 0043 to 0047 and 0055 to 0065, incorporated
herein by reference. More specific examples include
bis-(gamma-trimethoxysilylpropyl)amine,
gamma-aminopropyltrimethoxysilane,
N-beta-(aminoethyl)-gamma-aminopropyltrimethoxysilane,
gamma-glycidoxypropyl trimethoxysilane,
gamma-methacryloxypropyltrimethoxysilane, and
gamma-isocyanatopropyltrimethoxysilane.
[0044] The adhesive composition also contains one or more urethane
catalysts, i.e., materials that catalyze the reaction of isocyanate
moieties with water and/or a hydroxyl, mercapto or amino group.
Suitable catalysts include, for example, metallic catalysts such as
metal chelates, carboxylates and organometallic compounds, as well
as tertiary amines and mixtures of any two or more thereof.
Preferred metallic catalysts include tin carboxylates, organotin
compounds and tin alkanoates. A mixture of a tertiary amine and an
organometallic compound is preferred. Suitable organometallic
compounds include organotin compounds such as alkyltin oxides,
stannous alkanoates, dialkyltin dicarboxylates, dialkyltin
dimercaptanoates, and dialkyltin mercaptides. Stannous Metal
alkanoates include stannous octoate, bismuth octoate or bismuth
neodecanoate. Preferred examples of dialkyltin dicarboxylate
catalysts include 1,1-dimethyltin dilaurate, 1,1-dibutyltin
diacetate, 1,1-dimethyltin dimaleate and dimethyltin
dineodecanoate. Preferred metal alkanoates include bismuth octoate
or bismuth neodecanoate. Preferably, metallic catalyst(s) are
present in an amount of about 60 parts per million or greater based
on the weight of the adhesive composition, more preferably 120
parts per million or greater. Preferably, the metallic catalysts
constitute up to 1.0 percent, more preferably no more than 0.5
weight percent or up to 0.1 weight percent of the adhesive
composition.
[0045] Preferred tertiary amine catalysts include
dimorpholinodialkyl ether, a di((dialkylmorpholino)alkyl)ether,
bis-(2-dimethylaminoethyl)ether, triethylene diamine,
pentamethyldiethylene triamine, N,N-dimethylcyclohexylamine,
N,N-dimethyl piperazine 4-methoxyethyl morpholine,
N-methlmorpholine, N-ethyl morpholine and mixtures thereof. A
preferred dimorpholinodialkyl ether is dimorpholinodiethyl ether. A
preferred di((dialkylmorpholino)alkyl)ether is
(di-(2-(3,5-dimethylmorpholino)ethyl)-ether). Tertiary amines may
constitute, for example, at least 0.01 weight percent, at least
0.05 weight percent, at least 0.1 weight percent or at least 0.2
weight percent of the adhesive composition, and may constitute, for
example, up to 2.0 weight percent, up to 1.75 weight percent, up to
1.0 weight percent or up to 0.5 weight percent of the adhesive
composition.
[0046] In some embodiments, the amount of catalyst(s) is selected
such that the adhesive composition has a working time of at least 6
minutes, preferably at least 10 minute. Working time is the time
period after exposure to 23.degree. C./50% relative humidity
condition before the composition becomes unable to bond to a
substrate. Preferably, the composition of the invention is
formulated to provide a working time of about 6 minutes or greater
and more preferably about 10 minutes or greater. Preferably, the
working time is about 40 minutes or less and more preferably about
30 minutes or less.
[0047] The composition of the invention also comprises carbon
black. The carbon black used in this invention may be a conductive
carbon black, which is not specially treated (surface treated or
oxidized) to render it nonconductive. One or more nonconductive
carbon blacks may be used in conjunction with the conductive carbon
black.
[0048] Examples of useful, commercially available carbon black
products include those sold as RAVEN.TM. 790, RAVEN.TM. 450,
RAVEN.TM. 500, RAVEN.TM. 430, RAVEN.TM. 420, RAVEN.TM. 410,
RAVEN.TM. 1040 and RAVEN.TM. 1060 carbon blacks, all available from
Colombian, CSX.TM., Monarch.TM. and Elftex.TM. carbon blacks
available from Cabot Corporation and Printex.TM. carbon black
available from Degussa.
[0049] A preferred carbon black exhibits an oil absorption number
of at least 80, preferably at least 90 and more preferably at least
95, cubic centimeters of dibutyl phthalate per 100 g of carbon
black, as measured according to ASTM D-2414-09. In addition, the
carbon black desirably has an iodine number at least 80. The iodine
number is determined by ASTM D1510-11.
[0050] The adhesive composition may contain, for example, at least
10, at least 12 or at least 15 weight percent carbon black, based
on the total weight of the adhesive composition. The adhesive
composition may contain up to 35 weight percent, up to 30 weight
percent or up to 25 weight percent carbon black, based on the total
weight of the composition.
[0051] In addition to the foregoing materials, the adhesive
composition of the invention may contain various optional
ingredients.
[0052] The composition of the invention preferably comprises one or
more plasticizers to modify the rheological and viscosity
properties of the adhesive composition to a desired consistency.
Suitable plasticizers should be free of water, be inert to
isocyanate groups and be compatible with the prepolymer (i.e., does
not phase separate therefrom upon standing at room temperature).
Suitable plasticizers include straight and branched
alkylphthalates, such as diisononyl phthalate, dioctyl phthalate
and dibutyl phthalate, apartially hydrogenated terpene commercially
available as "HB-40", trioctyl phosphate, epoxy plasticizers,
toluene-sulfamide, chloroparaffins, adipic acid esters, castor oil
xylene, 1-methyl-2-pyrrolidinone and toluene, alkylbenzoate,
soybean oil methyl esters, dialkylbenzoate under K-Flex.TM., castor
or rapeseed oil methyl esters, alkyl sulfonic esters such as
Mesmoll.TM. from LANXESS Deutschland GmbH.
[0053] The amount of plasticizer in the adhesive composition of the
invention may be, for example, at least 1 weight percent, at least
5 parts by weight or greater or at least 10 parts weight percent,
based on the total weight of the adhesive composition. The
plasticizer is preferably present in an amount of no more than 40
weight percent or at most 30 parts by weight, on the same basis.
Most or all of the plasticizer is preferably introduced during the
preparation of the prepolymer.
[0054] The adhesive composition of the invention may further
comprise one or more additional particulate fillers such as, for
example, clay, calcium oxide, calcium carbonate, ground class,
ceramics such as boron nitride, metals, cross-linked organic
polymers, lignocelluosic powders, and fumed silica. A preferred
filler includes calcium carbonate. The calcium carbonate particles
may be untreated or surface modified by treatment with chemicals,
such as organic acids or esters of organic acids. In some
embodiments, calcium carbonate constitutes at least 1 weight
percent, at least weight percent, at least 3 weight percent or at
least 5 weight percent of the total weight of the adhesive
composition. Calcium carbonate may constitute, for example, up to
30 weight percent, up to 20 weight percent, up to 15 weight percent
or up to 10 weight percent, on the same basis.
[0055] The adhesive composition of the invention may further
comprise one or more moisture stabilizers, which function to
inhibit advancement and preventing premature crosslinking. Included
among such moisture stabilizers are diethylmalonate, alkylphenol
alkylates, paratoluene sulfonic isocyanates, benzoyl chloride and
orthoalkyl formates. Such stabilizers are preferably used in an
amount of at least 0.1 weight percent, at least 0.5 weight percent
or at least 0.8 weight percent, based on the total weight of the
adhesive composition, up to 5.0 weight percent, up to 2.0 weight
percent or up to 1.4 weight percent.
[0056] The adhesive compositions can also contain heat stabilizers
such as alkyl substituted phenols, phosphites, sebacates and
cinnamates. If present, a preferred heat stabilizer is an
organophosphite as disclosed in U.S. Pat. No. 6,512,033,
incorporated herein by reference. The heat stabilizer may
constitute at least 0.01 or at least 0.3 weight percent based on
the entire weight of the adhesive composition, up to at most 5
weight percent, up to 2 weight percent or up to 1.0 weight percent.
The adhesive composition may be devoid of such a heat
stabilizer.
[0057] The composition of the invention may further comprise an
ultraviolet light absorber (UV light stabilizer). Useful UV light
absorbers include benzophenones and benzotriazoles. Specific UV
light absorbers include those from BASF such as TINUVIN.TM. P,
2-(2'-hydroxy-5'-methylphenyl)-benzotriazole; TINUVIN.TM. 326,
2-(5-chloro-2H-benzotriazol-2-yl)-6-(1,1-dimethylethyl)-4-methylphenol;
TINUVIN.TM. 213 poly(oxy-1,2-ethanediyl),
(.alpha.,(3-(3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxyphen-
yl)-1-oxopropyl-.omega.-hydroxy; poly(oxy-1,2-ethanediyl),
(.alpha.,(3-(3-(AH-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxyphen-
yl)-1-oxopropyl)-.omega.-(.alpha.,(3-(3-(2H-benzotriazol-2-yl)-5-(1,1-dime-
thylethyl)-4-hydroxyphenyl)-1-oxopropyl); TINUVIN.TM. 327,
2-(3,5-di-tert-butyl-2-hydroxyphenol)-5-chlorobenzotriazole;
TINUVIN.TM. 571, 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol,
branched and linear; TINUVIN.TM. 328,
2-(2H-benzotriazol-2-yl)-4,6-bis(1,1-dimethylpropyl)phenol and from
Cytec such as CYASORB.TM. UV-9,2-hydroxy-4-methoxybenzophenone;
CYASORB.TM. UV-24, 2,2'-dihydroxy-4-methoxybenzophenone;
CYASORB.TM. UV-1164,
-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-(octyloxy)
phenol; CYASORB.TM. UV-2337,
2-(2'-hydroxy-3'-5'-di-t-amylphenyl)benzotriazole; CYASORB.TM.
UV-2908, 3,5-di-t-butyl-4-hydroxybenzoic acid, hexadecyl ester;
CYASORB.TM. UV-5337,
2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzotriazole;
CYASORB.TM. UV-531, 2-hydroxy-4-n-octoxybenzophenone; and
CYASORB.TM. UV-3638,
2,2-(1,4-phenylene)bis[4H-3,1-benzoxazin-4-one]. Among these,
2-hydroxy-4-n-octoxybenzophenone and
2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol, branched and
linear, are preferred. One or more UV light absorbers may
constitute at least 0.1 weight percent, at least 0.2 weight percent
or at least 0.3 parts by weight of the weight of the adhesive
composition, and may constitute up to 3 weight percent, up to 2
weight percent or up to 1 weight percent thereof.
[0058] The adhesive composition of the invention may further
include one or more light stabilizers. Preferred light stabilizers
included hindered amine light stabilizers such as TINUVIN.TM. 144,
n-butyl-(3,5-di-ter-butyl-4-hydroxybenzyl)bis-(1,2,2,6-pentamethyl-4-pipe-
ridinyl) malonate; TINUVIN.TM. 622, dimethyl succinate polymer with
4-hydroxy-2,2,6,-tetramethyl-1-piperidine ethanol; TINUVIN.TM. 77,
bis(2,2,6,6,-tetramethyl-4-piperidinyl) sebacate; TINUVIN.TM. 123,
bis-(1-octyloxy-2,2,6,6,tetramethyl-4-piperidinyl) sebacate;
TINUVIN.TM. 765, bis(1,2,2,6,6,-pentamethyl-4-piperidinyl)
sebacate; CHIMASSORB.TM. 944
poly[[6-[1,1,3,3-tetramethyl-butyl)amino]-1,3,5-triazine-2,4-diyl][(2-
,2,6,6-tetramethyl-4-piperidinyl)imino]-1,6-hexanediyl[(2,2,6-tetramethyl--
4-piperidinyl)imino]]) available from Cytec; CYASORB.TM. UV-500,
1,5-dioxaspiro(5,5)undecane 3,3-dicarboxylic acid,
bis(2,2,6,6,-tetramethyl-4-piperidinyl)ester; CYASORB.TM. UV-3581,
3-dodecyl-1-(2,2,6,6,-tetramethyl-4-piperidyl-pyrrolidin-2,5-dione)
and CYASORB.TM. UV-3346,
poly[(6-morpholino-s-triazine-2,4-diyl)[2,2,6,6-tetramethyl-4-piperidyl)i-
mino]-hexamethylene[(2,2,6,6-tetramethyl-4-piperidyl)imino]], all
available from Ciba-Geigy. Among these,
bis-(1-octyloxy-2,2,6,6,tetramethyl-4-piperidinyl) sebacate and
bis(1,2,2,6,6,-pentamethyl-4-piperidinyl) sebacate are preferred
types. The light stabilizer(s) may constitute at least 0.1 weight
percent, at least 0.2 weight percent or at least 0.3 weight percent
of the adhesive composition, and may constitute up to 3 weight
percent, up to 2 weight percent or up to 1.5 weight percent
thereof.
[0059] The adhesive composition of the invention may further
comprise a hydrophilic material that functions to draw atmospheric
moisture into the composition. This material enhances the cure
speed of the formulation by drawing atmospheric moisture to the
composition. Preferably, the hydrophilic material is a liquid.
Among the useful hydrophilic materials are pyrrolidines such as 1
methyl-2-pyrrolidone (or N-methyl pyrrolidone). Other hydrophilic
materials include ethylene oxide containing polyether polyols and
catalytically active polyols containing amine groups, which can be
present as separate ingredients or used as a polyol ingredient in
making the prepolymer described above. When added as a separate
ingredient, the hydrophilic material may constitute at least 0.1
weight percent or at least 0.3 weight percent of the total weight
of the adhesive composition, and may constitute up to 1.0 weight
percent or up to 0.6 weight percent thereof.
[0060] Optionally, the composition may further comprise a
thixotrope (rheological additive). Such thixotropes are well known
to those skilled in the art and include fumed silica, treated
silica and the like. The thixotrope may constitute at least 0.1
weight percent or at least 1 weight percent of the adhesive
composition, up to 10 weight percent or up to 2 percent by weight
thereof.
[0061] The various components of the adhesive composition
preferably are combined under an inert atmosphere in the absence of
oxygen and atmospheric moisture, so as to prevent premature
reaction. Preferably, the materials are blended under vacuum or an
inert gas, such as nitrogen or argon. Any amount of plasticizer not
added during prepolymer formation can be added when the prepolymer
is blended with the other components of the adhesive. The
ingredients are blended for a sufficient time to prepare a
well-blended mixture, preferably from about 10 to about 60 minutes.
Preferably the ingredients are blended at a temperature of about
25.degree. C. to about 90.degree. C. Once the adhesive composition
is formulated, it is packaged in a suitable container such that it
is protected from atmospheric moisture and oxygen.
[0062] The viscosity of the adhesive composition can be expressed
as a press flow viscosity, which is the amount of time (in seconds)
for 20 g of the adhesive composition to pass through a 4.0 mm
orifice under 552 kPa applied pressure at 23.degree. C. The press
flow viscosity may be, for example, at least 5 seconds, at least 10
seconds, at least 20 seconds or at least 25 seconds and may be, for
example, up to 200 seconds, up to 100 seconds or up to 60 seconds.
The amount of plasticizer in some embodiments is selected such that
the press flow viscosity of the adhesive composition is within
these ranges.
[0063] The composition of the invention is useful for bonding
substrates, which can be porous or nonporous. The composition is
applied to a first substrate and the composition on the first
substrate is thereafter contacted with a second substrate.
Thereafter, the composition is exposed to curing conditions, which
generally include the presence of moisture. The moisture can be
atmospheric moisture and/or liquid water. Curing can be performed
under ambient conditions, such as ambient humidity and temperatures
up to for example 40.degree. C. An elevated temperature may be
applied to accelerate the cure.
[0064] In a preferred embodiment, one substrate is glass or clear
plastic coated with an abrasion resistant coating and the other
substrate is a plastic, metal, fiberglass or composite substrate
which may optionally be painted or coated. The plastic coated with
an abrasion resistant coating can be any plastic which is clear,
such as polycarbonate, acrylic, hydrogenated polystyrene or
hydrogenated styrene conjugated diene block copolymers having
greater than 50 percent styrene content. The coating can comprise
any coating which is abrasion resistant such as a polysiloxane
coating. Preferably, the coating has an ultraviolet pigmented light
blocking additive. Preferably, the glass or coated plastic window
has an opaque coating disposed in the region to be contacted with
the adhesive to block UV light from reaching the adhesive. This is
commonly referred to as a frit. Preferably, the opaque coating is
an inorganic enamel or an organic coating.
[0065] In a preferred embodiment, the composition of the invention
is applied to the surface of the glass or coated plastic, along the
portion of the glass or coated plastic which is to be bonded to the
structure. The composition is thereafter contacted with the second
substrate such that a layer of the adhesive composition is disposed
at a bondline between the glass or coated plastic and the second
substrate. The composition is allowed to cure to form a durable
bond between the glass or coated plastic and the substrate.
[0066] In another embodiment, the composition may be applied to the
surface of the other substrate and then contacted with the glass or
coated plastic as described. The adhesive is applied in a bead to
the periphery of the window located such that it will contact the
window flange when placed in the vehicle. The window with the
adhesive located thereon is then placed into the flange with the
adhesive located between the window and the flange. The adhesive
bead preferably is a continuous bead that functions to seal the
junction between the window and the window flange. A continuous
bead of adhesive is a bead that is located such that the bead
connects at each end to form a continuous seal between the window
and the flange when contacted. Thereafter the adhesive is allowed
to cure.
[0067] In one embodiment the composition of the invention is used
to replace windows in structures or vehicles and most preferably in
vehicles. The first step is removal of the previous window. This
can be achieved by cutting the bead of the adhesive holding the old
window in place and then removing the old window. Thereafter the
new window is cleaned and primed. The old adhesive that is located
on the window flange can be cut to remove the old window. Although
the old adhesive can be removed before applying the adhesive of the
invention and assembling the new window onto the vehicle or
structure, it is common to apply the adhesive of the invention
overtop of a thin layer of the old adhesive that remains affixed to
the structure or vehicle. The window flange is preferably primed
with a paint primer. Thereafter the window with adhesive disposed
thereon is contacted with the window flange as described
hereinbefore. In another embodiment the adhesive can be applied to
the window flange instead of the window.
[0068] In another embodiment the compositions of the invention can
be used to bond modular components together. Examples of modular
components include vehicle modules, such as door, window or
body.
[0069] The adhesive composition of the invention preferably
exhibits a lap shear strength of at least 2.76 MPa (400 psi) after
being cured at conditions of 23.degree. C. and 50 percent relative
humidity for 7 days. The adhesive composition of the invention
preferably exhibits a Young's modulus of at least 3 MPa, as
measured according to ASTM D412 (Die C) after being cured under the
same conditions.
[0070] The adhesive composition of the invention preferably
exhibits a growth in press flow viscosity of no more than 100%,
more preferably no more than 50%, after being aged under nitrogen
for 3 days at 65.degree. C. before being cured.
[0071] The adhesive composition of the invention exhibits excellent
heat and hydrolytic stability. Hydrolytic and heat stability can be
assessed by evaluating the failure characteristics of the cured
adhesive after immersing substrates bonded together by the cured
adhesive in 90.degree. C. water for various times, as set forth in
the examples. The cured adhesive preferably exhibits 100% cohesive
failure mode when evaluated using the adhesion test describe in the
following examples, after being immersed in 90.degree. C. water for
10 days or more.
[0072] The following examples are provided to illustrate the
invention but are not intended to limit the scope thereof. All
parts and percentages are by weight unless otherwise indicated.
[0073] In the following examples:
[0074] VORANOL 220-056N POLYOL is a nominally difunctional,
poly(propylene oxide) having a hydroxyl number of 56 (equivalent
weight 1000), available from The Dow Chemical Company.
[0075] VORANOL 232-036N POLYOL is a nominally trifunctional
poly(propylene oxide) having a hydroxyl number of 36 (equivalent
weight 1558), available from The Dow Chemical Company.
[0076] The Polyester Polyol is commercially available from Evonik
as Dynacoll.TM. 7381.
[0077] Diisononyl Phthalate: plasticizer available from UPC
Technology.
[0078] MDI is methylene diphenyl diisocyanate (isocyanate
equivalent weight 125, isocyanate functionality 2.0) available as
Isonate 125 M from The Dow Chemical Company.
[0079] The Polymeric MDI is sold commercially by The Dow Chemical
Company as PAPI.TM. 20. It has an isocyanate functionality of 3.2
and an isocyanate equivalent weight of about 138.
[0080] Metacure.TM. T-9 is a stannous octoate urethane catalyst
available from Air Products.
[0081] Diethyl Malonate is a commercially available product from
Parchem Fine & Specialty Chemicals, New Rochelle, N.Y.,
USA.
[0082] The trimerized hexamethylene diisocyanate is Desmodur.TM.
N3300 from Covestro. It has an isocyanate functionality of greater
than 2.5 and an isocyanate content of 21.8% (isocyanate equivalent
weight about 193).
[0083] The dimorpholinodiethyl ether catalyst is Jeffcat.RTM.
DMDEE.TM. catalyst from Huntsman
[0084] The dimethyltin dineodecanoate catalyst is Fomrez.RTM. UL-28
catalyst from Momentive Performance Materials.
[0085] The mercaptosilane is gamma-mercaptopropyletrimethoxysilane,
commercially available from Momentive Performance Materials as
Silquest A-189.
[0086] The amino silane is bis-(gamma-trimethoxysilylpropyl)amine,
commercially available from Momentive Performance Materials as
Silquest.TM. 9627.
[0087] The epoxysilane is gamma-glycidoxypropyltrimethoxysilane,
commercially available from Momentive Performance Materials as
Silquest.TM. A-187.
[0088] The trinonylphenyl phosphite is available commercially as
Doverphos.RTM. 4 from Dover Chemical.
[0089] UVA Absorber A is Tinuvin.RTM. 571 from BASF.
[0090] The Light Stabilizer is Tinuvin.RTM. 765 from BASF.
[0091] The calcium carbonate is HUBERCARB.TM. Q325, available from
J. M. Huber.
[0092] BETASEAL.TM. 43518 is a silane-containing clear glass primer
from Dow Chemical Co.
[0093] BETASEAL.TM. 43520A is an isocyanate-containing black glass
primer from Dow Chemical Co.
[0094] BETASEAL.TM. 43526 is a silane-containing black glass primer
from Dow Chemical Co.
[0095] BETAPRIME.TM. 5500 is an isocyanate-containing black glass
primer from Dow Chemical Co.
EXAMPLE 1 AND COMPARATIVE SAMPLES A-C
A. Preparation of Prepolymer Solution 1
[0096] 363.68 g of Voranol 220-056 polyol, 527.04 g of Voranol
232-036 polyol and 32 g of diisononyl phthalate are charged into a
4-liter kettle, mixed and heated to 54.degree. C. under nitrogen.
All subsequent steps are performed under nitrogen. 160.64 g of
molten MDI is added and mixed in. 0.08 g of the stannous octoate
catalyst is added drop-wise. The temperature in the kettle rises
due to the exothermic heat of reaction; the reaction mixture is
maintained between 80.degree. C. and 90.degree. C. for 30 minutes.
The reaction mixture is then cooled to 60.degree. C. and 501.20 g
of diisononyl phthalate and 15.36 g of diethyl malonate are added
and mixed in for 30 minutes, followed by cooling to room
temperature. The resulting Prepolymer Solution 1 has an isocyanate
content of 1.25% by weight and a viscosity of 16,000 cps at
23.degree. C. as measured according to the procedure disclosed in
U.S. Pat. No. 5,922,809 at column 12, lines 38 to 49.
B. Preparation of Example 1 and Comparative Samples A, B and C
[0097] 210 g of calcium carbonate, 61.25 g of clay and 372.75 g of
Efltex.TM. S7100 carbon black are mixed and dried at 200.degree. C.
for about 20 hours, and then cooled in a closed container to form a
filler mixture. The Elftex carbon black has an oil absorption of
117 cc of dibutyl phthalate/100 g.
[0098] Separately, 1045.28 g of Prepolymer Solution 1, 35 grams of
a trimerized hexamethylene diisocyanate, 3.8 g of the dimorpholino
diethyl ether catalyst and 2.63 g of a 10% solution of the
dimethyltin dineodecanoate catalyst in diisononyl phthalate are
charged into a 2 gallon mixer. The mixture is degassed and mixed
under vacuum for 5 minutes. The vacuum is broken with nitrogen and
then, 8.75 g of the mercaptosilane is added, followed by additional
degassing and mixing under vacuum for 10 minutes. The vacuum is
broken again with nitrogen and then, the filler mixture is added
into the mixer. Then, the vacuum is applied slowly. When half of
the vacuum is achieved, mixing is started to wet out the fillers
for 2 minutes. The vacuum valve is then fully opened and further
mixing is continued under full vacuum for 15 minutes. Thereafter,
the mixture is scraped down and 10.5 g of trinonylphenyl phosphite
is added, followed by mixing under vacuum for 10 minutes. The
resulting adhesive composition (Example 1) is packaged into
airtight tubes which are stored in nitrogen-filled sealed aluminum
bags.
[0099] The press flow viscosity on adhesive samples is measured by
determining the amount of time (in seconds) for 20 g of the
adhesive composition to pass through a 4.0 mm orifice under
conditions of 552 kPa applied pressure at 23.degree. C., unless
otherwise specified. The press flow viscosity of Example 1 is 30
seconds. After aging Example 1 adhesive composition for 3 days at
54.degree. C. under nitrogen, the press flow viscosity increases
only slightly, to 35 seconds.
[0100] Sag performance is evaluated by the following method. A
metal panel of 10 cm height and 30 cm length is placed vertically
on its longest side. A right angle triangular bead of the adhesive
composition having a height of 1.8 cm and a base of 0.6 cm is
dispensed along the top edge of the panel with the bead height
perpendicular to the panel. After 30 minutes, the amount of drop or
sag of the tip of the adhesive bead is measured in millimeters.
Example 1 exhibits no measurable sag. After aging Example 1
adhesive for 3 days at 54.degree. C. under nitrogen, it still
exhibits no sag on this test.
[0101] Comparative Sample A is made in the same way, except the
mercaptosilane is replaced with an equal weight of the
aminosilane.
[0102] Comparative Sample B is made in the same way as Example 1,
except the mercaptosilane is replaced by an equal weight of the
epoxysilane.
[0103] Comparative Sample C is made in the same way as Example 1,
except the dimethyltin dineodecanoate catalyst solution is replaced
with an equal amount of Prepolymer Solution 1.
[0104] Round patties of Example 1 and Comparative Samples A and B
are cured for 7 days at conditions of 23.degree. C. and 50%
relative humidity. Test coupons are cut from these cured sample
patties and tested for tensile strength, elongation and Young's
modulus (from 1 to 10% extension), all according to ASTM D412 (Die
C). Results are as indicated in Table 1. Hardness is measured
according to ASTM D2240.
TABLE-US-00001 TABLE 1 Comparative Comparative Test Sample A*
Example 1 Sample B* Tensile strength, psi (kPa) 1271 1199 1327
Elongation, % 406 360 441 Young's Modulus, MPa 4.77 4.77 4.42 Shore
A hardness 69.1 69.6 66.7 *Not an example of the invention.
[0105] Peel adhesion sample of Example 1 and Comparative Samples A
and B is prepared as follows: dispense a triangular bead having a
6.3 mm base, a 12 mm height and 100 mm in length onto a bismuth
enamel glass coupon (width 25 mm.times.length 150 mm) primed with
BETAPRIME.TM. 5500. The bead is pressed with a release paper to
reach a 3 mm in thickness, which is then cured for 5 days at
23.degree. and 50% relative humidity. Thereafter, peel adhesion
sample is soaked for 5, 7, 10 and 12 days, respectively, in a
90.degree. C. hot water bath before testing. All peel adhesion
samples are prepared and tested in duplicate per adhesive sample
and per each test condition.
[0106] When tested, a slit (20-40 mm) is cut between the adhesive
bead end and the substrate. The cured bead is then cut with a razor
blade through to the tested substrate at a 60 degree angle while
pulling back the end of the bead at >90 degree angle. Notches
are cut about every 3-5 mm on the substrate. The degree of adhesion
is evaluated as adhesive failure (AF), thin film failure (TF)
and/or cohesive failure (CF). In case of AF, the cured bead can be
separated from the tested substrate surface, while in CF,
separation occurs within the sealant adhesive as a result of
cutting and pulling and TF is a special case of CF in which there
is a thin film of cured adhesive left on the substrate after
cutting and testing. Results are as indicated in Table 2.
TABLE-US-00002 TABLE 2 Hot Water Aged Peel Adhesion Results on
bismuth enamel glass panels coated with BETAPRIME .TM. 5500 glass
primer. Failure Mode Soaking Time, Comparative Comparative
90.degree. C. Water Sample A* Example 1 Sample B 5 days 100% CF
100% CF 100% CF 7 days 100% CF 100% CF 0% CF 10 days 30-40% CF.sup.
100% CF 0% CF 12 days N.D. 100% CF N.D.
[0107] Peel adhesion testing is performed in the same manner on
bismuth enamel glass panels primed with BETASEAL.TM. 43526. Results
are as indicated in Table 3.
TABLE-US-00003 TABLE 3 Hot Water Aged Peel Adhesion Results on
bismuth enamel glass panels coated with BETASEAL .TM. 43526 glass
primer Failure Mode Soaking Time, Comparative Comparative
90.degree. C. Water Sample A* Example 1 Sample B 5 days 100% CF
100% CF 100% CF 7 days 100% CF 100% CF 0% CF 10 days 40-100% CF
.sup. 100% CF 0% CF 12 days 0% CF 100% CF N.D.
[0108] Peel adhesion testing for Example 1 is also performed on a
metal panel freshly coated with Gen.TM. V paint without paint
primer. Example 1 exhibits 100% CF on the Gen.TM. V paint. When
Comparative Sample C is evaluated in the same manner, the failure
mode is only 10% CF. These results demonstrate the advantage of
using a mixture of the dimorpholino diethylether catalyst with a
metal-containing catalyst.
[0109] The lap shear adhesion of Example 1 is evaluated according
to SAE J1529 test procedure. Duplicate test specimens are made by
applying a triangular bead having a base of approximately 6.3 mm
and a height of 8 mm height is applied along the width of a 25 mm
by 100 mm of a bismuth-zinc fritted glass primed with both
Betaseal.TM. 43518 and Betaseal.TM. 43520A. An e-coated metal
coupon is immediately pressed onto the adhesive bead to form an
overlap of 6.3 mm and a 6.3 mm thick adhesive bead between the
substrates. The samples are cured for 3 days at 23.degree. C. and
50 percent relative humidity. One sample is then evaluated
immediately for lap shear strength at a pull rate of 50 mm/min.
Another sample is further aged for 14 days at 40.degree. C. and
100% relative humidity before testing. Results are as indicated in
Table 4.
TABLE-US-00004 TABLE 4 Lap Shear Adhesion Results for Example 1 Lap
Shear Strength, Failure Aging Conditions kPa (psi) Mode None 3213
(495) 100% CF 14 Days/100 F./100% RH 2964 (430) 100% CF
EXAMPLES 2 AND 3
[0110] Example 2 is prepared in the same general manner as Example
1, from the following ingredients:
TABLE-US-00005 Ingredient Weight % Prepolymer Solution 1 56.33%
Diisononyl Phthalate 3.0% Polymeric MDI 2.0% Trimerized
hexamethylene diisocyanate 2.0% Dimorpholino ether 0.217%
Dimethyltin dineodecanoate (10% in diisononyl phthalate) 0.15%
Mercaptosilane 0.5% Elftex .TM. S7100 Carbon black 22.7% Clay 3.5%
CaCO.sub.3 9.0% Trisnonylphenyl phosphite 0.6%
[0111] Example 3 is made in the same manner, except a carbon having
an oil absorption of only 72 cc dibutyl phthalate/100 g
(Monarch.TM. 120, from Cabot Corporation) is used instead of the
Elftex.TM. carbon.
[0112] Example 2 exhibits an initial press flow viscosity of 48
seconds. Its press viscosity does not when it is heat aged for 3
days at 54.degree. C. Example 2 exhibits no sag when evaluated
before and after heat aging for 3 days at 54.degree. C. Its Young's
modulus (1-10% extension) is 8.76 MPa. Tensile strength is about
9000 kPa (1300 psi) and elongation is 248%. Shore A hardness is
81.
[0113] Example 3 exhibits an initial sag of 20 mm on the sag test.
The results of Example 2 and Example 3 demonstrate the advantage of
using a carbon black having high oil absorption in conjunction with
the mercaptosilane.
EXAMPLE 4 AND COMPARATIVE SAMPLE D
[0114] Example 4 is prepared in the same general manner as Example
1, from the following ingredients:
TABLE-US-00006 Ingredient Weight % Prepolymer Solution 1 56.93%
Diisononyl Phthalate 2.6% Polymeric MDI 1.0% Trimerized
hexamethylene diisocyanate 2.0% Dimorpholino diethylether 0.17%
Dimethyltin dineodecanoate (10% in diisononyl phthalate) 1.0%
Mercaptosilane 1.6% Elftex .TM. S7100 Carbon black 21.2% Clay 13.0%
UVA Absorber A 0.5%
[0115] Comparative Sample D is made in the same manner, except the
mercaptosilane is replaced with an equal weight of an
aminosilane.
[0116] Example 4 exhibits no sag on the sag test after 3 day aging
at 65.degree. C. After same heat aging conditions, comparative
Sample D exhibits 9 mm of sag on the test, and in addition the
entire applied bead slides downward by about 1 mm, which is a very
poor result.
[0117] Example 4 has an initial press viscosity of 43 seconds,
which increases to about 51 seconds after the adhesive is aged for
3 days at 65.degree. C. Example 4 has a viscosity heat growth of
18.6%. Example 4 has a much superior rheological stability than the
Sample D.
EXAMPLE 5
A. Prepolymer Solution 2
[0118] 280 grams of diisononyl phthalate are placed in a reaction
vessel under nitrogen and heated to 50.degree. C. 172.8 grams of
molten MDI are added and mixed in, followed by the gradual addition
of 1147.2 grams of the molten Polyester Polyol. The resulting
reaction mixture is reacted under nitrogen for 40 minutes at 80 to
90.degree. C., and the resulting Prepolymer Solution 2 is then
stored in an airtight dry container. Prepolymer Solution 2 is solid
at room temperature and has an isocyanate content of 2.0% by
weight.
B. Preparation of Example 5
[0119] 128 grams calcium carbonate, 56 grams clay and 348 grams
Efitex.RTM. S7100 carbon black are mixed and dried at 200.degree.
C. for about 20 hours, and then cooled in a closed container to
form a filler mixture.
[0120] Separately, the mixer vessel is first heated up to
65.degree. C. with a heating jacket. Afterwards, 963.04 g of
Prepolymer Solution 1, 12.8 g of the MDI, 40 grams of the
trimerized hexamethylene diisocyanate, 0.96 g of the dimorpholino
diethylether catalyst and 19.2 g of the 10% dimethyltin
dineodecanoate catalyst in diisononyl phthalate are charged and
mixed together under vacuum for five minutes. Then, 12.8 g of the
mercaptosilane is added into mixer and mixed in under vacuum for 10
minutes. The vacuum is broken with nitrogen and the filler mixture
is added. Then, the vacuum is applied slowly. When half of the
vacuum is achieved, mixing is started to wet out the fillers for 2
minutes. The vacuum valve is then fully opened and further mixing
is continued under full vacuum for 15 minutes. Thereafter, the
mixture is scraped down and 1.39 g each of UVA Absorber A and the
Light Stabilizer, 1.22 grams of trinonylphenyl phosphite and 14.4 g
of molten Prepolymer Solution 2 are then added and mixed in under
vacuum for another 10 minutes. The resulting adhesive composition
(Example 5) is packaged into tubes.
[0121] Example 5 has an initial press flow viscosity of 47 seconds,
which increases only to 51 seconds after Example 5 is aged for 3
days at 54.degree. C. Example 5 exhibits no sag, either before or
after heat aging. After curing for 7 days at 23.degree. C. and 50%
relative humidity, Example 5 exhibits a tensile strength of 7880
kPa (1143 psi), and elongation of 286%, a Young's modulus of 6.21
MPa and a Shore A hardness of 76.
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