U.S. patent application number 11/790572 was filed with the patent office on 2007-11-01 for polyurethane adhesive for windshield applications.
This patent application is currently assigned to Sika Corporation. Invention is credited to Norman Blank, Thomas Bove, Steven A. Rosenberg, Hans Peter Tschan, Adrian Van Maurik, Hong Yao.
Application Number | 20070251629 11/790572 |
Document ID | / |
Family ID | 23117071 |
Filed Date | 2007-11-01 |
United States Patent
Application |
20070251629 |
Kind Code |
A1 |
Rosenberg; Steven A. ; et
al. |
November 1, 2007 |
Polyurethane adhesive for windshield applications
Abstract
A polyurethane adhesive which is useful in bonding porous and
non-porous surfaces is provided. The adhesive is especially useful
in bonding windshield glass into automotive frames under a variety
of environmental conditions, particularly in after market
windshield replacement applications. The polyurethane includes at
least one urethane prepolymer which is based on at least one
thermoplastic polyol. In one embodiment, the urethane prepolymer
may be formed from one or more polyisocyanates, one or more
polyetherpolyols and one or more thermoplastic polyesterpolyols,
wherein the prepolymer has a free isocyanate content of from about
0.6 to about 3.5% by weight, based on the weight of the
polyurethane. In another embodiment, a one-part adhesive
composition is provided which includes an isocyanate-functional and
thermoplastic polyurethane prepolymer having a free isocyanate
content of from about 0.6 to about 3.5% by weight, based on the
weight of the polyurethane, and a combination of several catalysts
which are capable of catalyzing the reaction of isocyanate moieties
with isocyanate-reactive moieties while providing less temperature
dependent catalyzing of the reaction between isocyanate moieties
and water. Also provided is a process for bonding two or more
substrates together utilizing the polyurethane adhesive. In
automotive windshield replacement applications, the polyurethane
adhesive allows for a sufficient working time and development of
green strength to provide a safe drive-away time within 1 hour at a
temperature from about 0 to about 100.degree. C.
Inventors: |
Rosenberg; Steven A.;
(Succasunna, NJ) ; Yao; Hong; (Parsippany, NJ)
; Bove; Thomas; (Rahway, NJ) ; Van Maurik;
Adrian; (Zurich, CH) ; Tschan; Hans Peter;
(Moriken, CH) ; Blank; Norman; (Uster,
CH) |
Correspondence
Address: |
BINGHAM MCCUTCHEN LLP
2020 K Street, N.W.
Intellectual Property Department
WASHINGTON
DC
20006
US
|
Assignee: |
Sika Corporation
|
Family ID: |
23117071 |
Appl. No.: |
11/790572 |
Filed: |
April 26, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10144803 |
May 15, 2002 |
7226523 |
|
|
11790572 |
Apr 26, 2007 |
|
|
|
60290673 |
May 15, 2001 |
|
|
|
Current U.S.
Class: |
156/108 |
Current CPC
Class: |
C08G 18/12 20130101;
C09J 175/04 20130101; C08G 18/12 20130101; C08G 18/10 20130101;
C08G 18/307 20130101; C08G 18/289 20130101; C08G 18/307 20130101;
C08G 18/12 20130101; C08G 18/10 20130101 |
Class at
Publication: |
156/108 |
International
Class: |
E06B 3/56 20060101
E06B003/56 |
Claims
1-86. (canceled)
87. An automotive windshield replacement method which comprises: a)
applying an adhesive to an automotive windshield and/or an
automobile body substrate, said adhesive comprising at least one
urethane prepolymer formed from reaction materials comprising: i)
isophorone diisocyanate and/or 4,4'-diphenylmethanediisocyanate:
ii) an ethylene oxide-end-capped triol having a weight average
molecular weight of about 4500 to about 5000; and iii) hexanediol
adipate b) contacting the substrates together, within the working
time of the adhesive, along at least a portion of the substrate(s)
to which the adhesive has been applied; and c) allowing the
adhesive to bond the substrates together.
88. An automotive windshield replacement method according to claim
87, wherein said reaction materials further comprise at least one
of a polypropylene glycol and a propylene oxide-end-capped
triol.
89. An automotive windshield replacement method according to claim
88, wherein said reaction materials comprise a polypropylene glycol
having a weight average molecular weight of about 3500 to about
4500.
90. An automotive windshield replacement method according to claim
87, wherein the adhesive (1) has a tensile strength of 1.0 MPa or
greater when measured at a strain rate of 1 meter/second, (2) has a
compression force of less than about 0.18 MPa when measured at
5.degree. C., (3) provides a safe drive-away time according to U.S.
Federal Motor Vehicle Safety Standards of one hour or less from
application of the adhesive to the windshield and/or automobile
body, and (4) provides a working time of about 6 to about 15
minutes.
91. An automotive windshield replacement method which comprises: a)
applying an adhesive to an automotive windshield and/or an
automobile body substrate, said adhesive comprising at least two
urethane prepolymers, the first said prepolymer formed from
reaction materials comprising: i) isophorone diisocyanate and/or
4,4'-diphenylmethanediisocyanate, and ii) an ethylene
oxide-end-capped triol having a weight average molecular weight of
about 4500 to about 5000; and the second said prepolymer formed
from reaction materials comprising: i) isophorone diisocyanate
and/or 4,4'-diphenylmethanediisocyanate, and ii) a thermoplastic
polyesterpolyol; b) contacting the substrates together, within the
working time of the adhesive, along at least a portion of the
substrate(s) to which the adhesive has been applied; and c)
allowing the adhesive to bond the substrates together.
92. An automotive windshield replacement method according to claim
90 wherein the reaction materials of said second prepolymer
comprise hexanediol adipate.
93. An automotive windshield replacement method according to claim
92 wherein the reaction materials of said first prepolymer further
comprise at least one of a polypropylene glycol and a propylene
oxide-end-capped triol.
94. An automotive windshield replacement method according to claim
93, wherein said reaction materials of said first prepolymer
comprise a polypropylene glycol having a weight average molecular
weight of about 3500 to about 4500 comprise hexanediol adipate.
95. An automotive windshield replacement method according to claim
93, wherein said reaction materials of said first prepolymer
comprise a propylene oxide-end-capped triol.
96. An automotive windshield replacement method according to claim
91 wherein the reaction materials of said first prepolymer further
comprise at least one of a polypropylene glycol and a propylene
oxide-end-capped triol.
97. An automotive windshield replacement method according to claim
96, wherein said reaction materials of said first prepolymer
comprise a polypropylene glycol having a weight average molecular
weight of about 3500 to about 4500.comprise hexanediol adipate.
98. An automotive windshield replacement method according to claim
96, wherein said reaction materials of said first prepolymer
comprise a propylene oxide-end-capped triol.
99. An automotive windshield replacement method according to claim
91, wherein the adhesive (1) has a tensile strength of 1.0 MPa or
greater when measured at a strain rate of 1 meter/second, (2) has a
compression force of less than about 0.18 MPa when measured at
5.degree. C., (3) provides a safe drive-away time according to U.S.
Federal Motor Vehicle Safety Standards of one hour or less from
application of the adhesive to the windshield and/or automobile
body, and (4) provides a working time of about 6 to about 15
minutes.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/144,803, filed May 15, 2002 which claims
the benefit of priority under 35 U.S.C. .sctn. 119(e) of U.S.
provisional application No. 60/290,673, filed May 15, 2001, and
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to polyurethane adhesives
which are useful in bonding porous and nonporous surfaces and to a
method of bonding two or more substrates together with a
polyurethane adhesive. More particularly, the present invention
relates to polyurethane adhesives which are especially useful in
bonding windshield glass into an automotive frame under varied
environmental conditions and to a method of bonding windshield
glass to an automotive frame using a polyurethane adhesive.
[0004] 2. Brief Description of Art
[0005] A variety of adhesives, including polyurethanes, are useful
for bonding to porous and non-porous substrates (see, e.g., U.S.
Pat. Nos. 4,374,237, 4,687,533, 5,603,798, 5,672,652 and 5,852,103,
each of which is incorporated herein by reference). Polyurethane
adhesive compositions typically comprise at least one polyurethane
prepolymer. Both one and two-part polyurethanes are known and may
be used to bond a variety of substrates, including glass to
metal.
[0006] In general, two-component urethane adhesive systems can
provide curing which is less dependent upon weather condition than
one-component urethane adhesive systems. For this reason, a
two-component system is generally thought to have more flexibility
under a variety of application conditions, especially during the
winter as compared with a one-part urethane adhesive.
[0007] Two-part urethane adhesives, however, typically require
special application equipment. For example, a special application
gun with an electrically powered mixing mechanism which mixes the
two parts in a specific ratio prior to application may be required.
Such applicators are more difficult and costly to use than
applicators for one-part urethane adhesives. Further, the improper
mixing of two-component urethane system can result in poor final
physical properties of the adhesives and even in poor adhesion. The
use of a two-part system at high temperature may also be
disadvantageous since a too rapid initial cure may provide such a
urethane adhesive with a short working time.
[0008] In comparison, a one-part urethane adhesive provides
improved ease of use since moisture cures the adhesive without any
added mechanical mixing. Conventional one-part polyurethane
adhesives are strongly dependent on the environmental conditions
because of the need for such moisture curing. Hardening and in turn
the amount of time needed before an adhesive product may be used
are therefore affected by weather conditions. This is particularly
true in the winter time where low temperature and low humidity
conditions reduce the curing rate of one-component polyurethane
adhesives no matter what kind of catalyst and how much of it is
used in the formulation. In addition, using too much strong
catalyst usually adversely impacts storage stability and can also
dramatically shorten the working time at high temperature and high
humidity conditions.
[0009] The use of thermoplastic materials in polyurethanes for
one-part adhesives further allows easy application at elevated
temperatures and improved green strength once the material cools
down. One example of the use of thermoplastic materials in
polyurethane-based adhesives is Hot-Melt Thermoplastic Urethane
Elastomers (Hot Melt TPU). See, e.g., U.S. Pat. No. 5,936,018.
Thermoplastic urethanes (TPU) are reacted and neutral materials,
which need high temperatures (usually >100.degree. C.) to become
soft/viscous and have very fast setting times (usually a few
seconds to several minutes). Another example of a reactive hot-melt
material is an isocyanate group end-capped urethane prepolymer
comprising thermoplastic polyester-polyol (e.g., see EP 0-909-771
A1).
[0010] In the automotive after-market replacement industry, glass
may be bound into automobiles through the use of either one-part or
two-component curable polyurethane adhesives. Two-part polyurethane
adhesives may be used since they offer rapid initial cure allowing
for rapid drive-away times. Two-part polyurethane adhesives are
well known for this application; see, e.g., U.S. Pat. No.
4,835,012, 5,672,652 and 5,852,137, incorporated herein by
reference.
[0011] Despite the relatively rapid drive-away times afforded by
two-part polyurethane adhesives, faster curing polyurethane
adhesives which allow even faster drive-away times are in demand.
For instance, safe drive-away times of about 60 minutes or less
from application, and more preferably about 30 minutes or less from
application, are preferred. However, a trade-off exists between
cure time, adhesive strength and working time, generally defined as
the period from application of an adhesive until the adhesive
becomes too intractable to work with. For example, if an adhesive
cures too rapidly, a window installer may lose the necessary time
to install and properly place the glass into the frame before the
adhesive becomes too intractable to work with. For these reasons,
the minimum working time for such windshield replacements is about
6 to 12 minutes.
[0012] A one-part moisture curable polyurethane is preferably used
when glass is installed in automobiles since the equipment needed
for the application of such an adhesive in an either automobile
assembly plant or as an after market replacement is less expensive
than the equipment needed to apply a two-component adhesive. One
part polyurethane adhesives are disclosed in U.S. Pat. Nos.
4,374,237, 4,687,533, 5,922,809, 6,133,395 and 6,133,398, the
disclosures of which are herein incorporated by reference.
[0013] Generally, thermoplastic urethanes, either TPU's or
prepolymers, will boost both green strength, which is desired, and
the compression force required to install such a windshield, which
is not desired. As mentioned above, higher green strength may
shorten safe drive-away times, but higher compression forces
required to install the windshield may shorten the working
time.
[0014] Federal Transportation Agency regulations require
windshields to remain in place at crashes of up to 30 mph (48
kni/h). Federal Motor Vehicle Safety Standards (FMVSS) 208, 212 and
216 describe certain requirements which are pertinent to automotive
windshield replacements. In particular, these standards set forth
the minimum performance characteristics required of a windshield
retention system. To meet such standards, it has been shown through
crash studies of the forces on a windshield, both due to
deceleration and airbag impact on the windshield, that a tensile
strength of the adhesive should be preferably at least about 145
psi (1.0 MPa) at the designated drive away time measured at a
strain rate of 1 meter/second.
[0015] For at least the above reasons, it is desirable to provide a
one-part polyurethane adhesive which facilitates faster safe
drive-away times, which meets the strength requirements to allow
for the safe replacement of automotive windshields and which still
provides for a reasonable working time to facilitate proper
placement of glass in window frames.
OBJECTS AND SUMMARY OF THE INVENTION
[0016] It is a general object of the invention to provide a
polyurethane adhesive which is useful in bonding porous and
non-porous surfaces. The adhesive is especially useful in bonding
windshield glass into automotive frames under a variety of
environmental conditions, particularly in after-market windshield
replacement applications. The polyurethane includes at least one
urethane prepolymer which is based on at least one thermoplastic
polyol.
[0017] In one embodiment, the urethane prepolymer may be formed
from the reaction product of: [0018] A) one or more
polyisocyanates, preferably one diisocyanate; [0019] B) or more
liquid polyetherpolyols; preferably an ethylene oxide end capped
triol of relatively large molecular weight and/or one propylene
oxide (PO) end capped triol having a relatively small molecular
weight, or a polypropylene glycol; and [0020] C) one or more
thermoplastic polyesterpolyols; wherein the prepolymer has a free
isocyanate content of from about 0.6 to about 3.5 % by weight,
preferably from about 0.9 to about 2.5 % by weight, based on the
weight of the polyurethane.
[0021] In another embodiment, the urethane prepolymer may be formed
from the reaction product of: [0022] A) one or more
polyisocyanates, preferably one diisocyanate; [0023] B) two or more
liquid polyetherpolyols; preferably an ethylene oxide end capped
triol of relatively large molecular weight and one propylene oxide
(PO) end capped triol having a relatively small molecular weight,
or a polypropylene glycol; and [0024] C) and two or more
thermoplastic polyesterpolyols; wherein the prepolymer has a free
isocyanate content of from about 0.6 to about 3.5 % by weight,
preferably from about 0.9 to about 2.5% by weight, based on the
weight of the polyurethane.
[0025] In another embodiment, a one-part adhesive composition is
provided which includes: [0026] A) an isocyanate-functional and
thermoplastic polyurethane prepolymer having a free isocyanate
content of from about 0.6 to about 3.5% by weight, preferably from
about 0.9 to about 2.5% by weight, based on the weight of the
polyurethane; and [0027] B) one or more catalysts which are capable
of catalyzing the reaction of isocyanate moieties with
isocyanate-reactive moieties while providing less temperature
dependent catalyzing of the reaction between isocyanate moieties
and water.
[0028] In yet another embodiment, a one-part adhesive composition
is provided which includes: [0029] A) an isocyanate-functional and
thermoplastic polyurethane prepolymer having a free isocyanate
content of from about 0.6 to about 3.5% by weight, preferably from
about 0.9 to about 2.5% by weight, based on the weight of the
polyurethane; and [0030] B) a combination of several catalysts
which are capable of catalyzing the reaction of isocyanate moieties
with isocyanate-reactive moieties while providing less temperature
dependent catalyzing of the reaction between isocyanate moieties
and water.
[0031] A process for bonding two or more substrates together
utilizing the polyurethane adhesive is also provided by the
invention. This process comprises contacting an adhesive
composition of the invention (preferably at elevated temperature)
with at least one of the substrates and contacting the substrates
together, before the applied adhesive cures, along the portion of
the substrate(s) to which the adhesive has been applied, and
allowing the adhesive to cure and bond the substrates together.
[0032] In another embodiment the thermoplastic prepolymer of this
invention has a working time which will allow for the replacement
of an automotive windshield. Preferably the working time is about
6-15 minutes, more preferably about 8-12 minutes. In automotive
windshield replacement applications, the polyurethane adhesive
allows for a sufficient working time and development of green
strength to provide a safe drive-away time within about 1 hour or
less from application, preferably about 30 minutes or less from
application, at a temperature from about 0 to about 100.degree. F.
It is preferred that the tensile strength of the polyurethane
adhesive be at least about 115 psi (0.8 MPa) or greater, more
preferably about 145 psi (1.0 MPa) or greater, measured at a strain
rate of 1 meter/second under a variety of temperature and humidity
conditions.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE
INVENTION
[0033] In general, the diisocyanate compound used as a co-reactant
in the preparation of the urethane prepolymer may be selected from
those commonly accepted for the manufacture of urethane resins.
Specific examples include 2,4-toluene diisocyanate, 2,6-toluene
diisocyanate, phenylene diisocyanate, xylene diisocyanate,
diphenylmethane-4,4'-diisocyanate, naphthalene-1,5-diisocyanate and
hydrogenates thereof, methylene diisocyanate, ethylene
diisocyanate, propylene diisocyanate, tetramethylene diisocyanate,
hexarnethylene diisocyanate, isophorone diisocyanate,
1-methyl-2,4-diisocyanate cyclohexane, 1-methyl-2,6-diisocyanate
cyclohexane, dicyclohedxthylmethane diisocyanate, triphenylmethane
triisocyanate and the like. These compounds may be used alone or in
combination.
[0034] Polyols useful in the preparation of the prepolymers
include, for example, polyether polyols, polyester polyols,
poly(alkylene carbonate)polyols, hydroxyl-containing
polythioethers, polymer polyols, and mixtures thereof. Polyether
polyols are well-known in the art and include, for example,
polyoxyethylene, polyoxypropylene, polyoxybutylene, and
polytetramethylene ether diols and triols which are prepared by
reacting an unsubstituted or halogen- or aromatic-substituted
alkylene oxide with an initiator compound containing two or more
active hydrogen groups such as water, ammonia, a polyalcohol, or an
amine. Such methods are described, for example, in U.S. Pat. Nos.
4,269,9945; 4,218,543; and 4,374,210; which are herein incorporated
by reference in their entirety. In general, polyether polyols may
be prepared by polymerizing alkylene oxides in the presence of an
active hydrogen-containing initiator compound.
[0035] Suitable alkylene oxides may include, e.g., ethylene oxide,
propylene oxide, butylene oxides, styrene oxide, epichlorohydrin,
epibromohydrin, and mixtures thereof. Suitable initiator compounds
may include, e.g., water, ethylene glycol, propylene glycol,
butanediol, hexanediol, glycerin, trimethylol propane,
pentaerythritol, hexanetriol, sorbitol, sucrose, hydroquinone,
resorcinol, catechol, bisphenols, novolac resins, phosphoric acid,
amines, and mixtures thereof.
[0036] The thermoplastic materials according to the invention are
so-called "warm-melt" materials with flowing and re-solidification
points which are usually below 100.degree. C., preferably below
80.degree. C., more preferably below 70.degree. C., and most
preferably below 60.degree. C.
[0037] Both crystal and amorphous polyesters may be used as
thermoplastic materials in the polyurethanes of the invention.
[0038] The "working time" (sometimes also referred to as "open
time" or "setting time") of a windshield repair adhesive is defined
as the period from application of adhesive onto the surfaces to be
bonded until the adhesive becomes too intractable to work with. An
adhesive is generally too intractable to work when that the
material becomes too hard to press or to re-adjust the windshield
position, or the surface of the adhesive has cured sufficiently
producing a surface skin so that windshield can no longer be bound
into the automobile body. The working times of windshield repair
adhesives according to the invention are preferably about 6-15
minutes, and more preferably about 8-12 minutes.
[0039] The working time may also be described quantitatively based
upon the tack free time of the surface of the adhesive and the
compression force of the adhesive. The tack free time is the amount
of time for a skin to develop on the surface of the adhesive. A
standard drying measurement technique, typically at 73.degree. F.
and 50% relative humidity, is generally utilized to record the tack
free time as the time period until a needle dragged across the
surface of an adhesive applied onto a glass strip produces a ripple
in the adhesive. The tack free time has a bearing on the working
time since the bonding of an adhesive bead is generally reduced or
prevented following the development of a skin layer. The
compression force of the adhesive refers to the amount of force
required to press two substrates together following application of
an adhesive bead to at least one of the surfaces such that the
adhesive is capable of being compressed and the substrates properly
bonded. The compression force has a bearing on the working time,
particularly for windshield installation applications, since an
adhesive that requires too high a compression force may not allow
an installer to achieve a proper bond meeting Federal Motor Vehicle
Safety Standards. In general, the compression force of a
polyurethane adhesive bead for windshield installation (measured at
5.degree. C. and after 10 minutes from application of a bead of the
adhesive to a substrate) should be less than about 0.25 MPa,
preferably less than about 0.18 MPa and more preferably less than
about 0.1 MPa. The working time is the lesser of the tack free time
and the adhesive curing time which results in an adhesive bead
compression force of less than about 0.25 MPa, preferably less than
about 0.18 MPa and more preferably less than about 0.1 MPa.
[0040] The term "Safe Drive-Away Time" (SDAT), as defined herein,
is the time period from which a windshield is bound onto an
automobile body until the adhesive becomes so strong that the
windshield would remain in place in case the automobile crashes at
a speed of up to 30 mph (48 km/h) according to U.S. Federal Motor
Vehicle Safety Standards (FMVSS 208, 212 and 216). To meet such a
standard, the tensile strength of the adhesive at the designated
drive-away time should preferably be about 115 psi (0.8 MPa) or
greater, more preferably about 145 psi (1.0 MPa) or greater when
measured at a test speed (strain rate) of 1 meter/second. The
polyurethane adhesive compositions according to the invention
provide Safe Drive-Away Times at temperatures from about 0 to about
100.degree. F. (-32 to 37.8.degree. C.) over a variety of humidity
conditions.
[0041] It is preferred that the polyurethane adhesive compositions
according to the invention have a tensile strength at the
designated drive-away time of about 115 psi (0.8 MPa) or greater,
more preferably about 145 psi (1.0 MPa) or greater when measured at
a test speed (strain rate) of 1 meter/second and a compression
force (measured at 5.degree. C. and after 10 minutes from
application of a bead of the adhesive to a substrate) of less than
about 0.25 MPa, preferably less than about 0.18 MPa and more
preferably less than about 0.1 MPa.
[0042] In the practice of the invention, there may be used various
additives commonly known in the art which include plasticizers,
fillers, thixotropic agents, tackifiers, catalysts, ultraviolet
absorbers, dyes, pigments, flame retardants and the like. Typical
plasticizers are chosen from derivatives of benzoic acid, phthalic
acid (e.g. phthalates, such as dibutyl-, dioctyl-, dicyclohexyl-,
diisooctyl-, diisodecyl-, dibenzyl- or butylbenzylphthalate),
trimellitic acid, pyromellitic acid, adipic acid, sebacic acid,
fumaric acid, maleic acid, itaconic acid and citric acid and of
polyester, polyether and epoxy and the like. Suitable fillers
include silicic acid derivatives, talc, metallic powder, calcium
carbonate, clay, carbon black among others. Thixotropic agents
typically include bentonite, anhydrous silicic acid, urea
derivatives and the like. Suitable catalysts include dibutyltin
dilaurate, dioctyltin dilaurate, zinc octylate, organic bismuth
compounds, triethylenediamine, amine compounds such as morpholine
amine and the like. Examples of such catalysts are disclosed in
U.S. Pat. Nos. 5,922,809, 6,133,395 and 6,133,398, herein
incorporated by reference. Combinations of catalysts may also be
used, preferably a combination of one or more dialkyltin compounds
such as a dialkyltin dicarboxylates, more preferably dibutyltin
dilaurate and one or more amine compounds, such as a
dimorpholinodialclkylethers and/or dimorpholino substituted
polyalkylene glycols.
[0043] Preferably these additional components are present in the
following ranges:
[0044] the at least one plasticizer, preferably in an amount from
about 10 to about 25 percent by weight, more preferably from about
15 to about 20 percent by weight and/or
[0045] the at least one filler, preferably in an amount from about
5 to about 50 percent by weight, especially in an amount from about
8 to about 15 percent by weight, and/or
[0046] the at least one additive, preferably in an amount from
about 0.001 to about 5 percent by weight,
[0047] whereby said percentages are with reference to the total
polyurethane adhesive mixture.
[0048] Further auxiliary agents or additives may be included,
selected from:
[0049] adhesion promoters, especially silane-containing compounds,
which may additionally contain at least one reactive group, such as
epoxy-, isocyanate-, amine groups or double bonds,
[0050] dyes or pigments,
[0051] polyurethane catalysts, such as lead and/or tin and/or other
metal compounds, occasionally combined with the use of further
polyurethane catalysts, especially of tertiary amine-containing
catalysts,
[0052] UV-absorbing agents or stabilizers, such as phenolic
antioxidants and screening agents.
[0053] Preferred polyurethane prepolymers of the present invention
are those formed of the following components:
[0054] a) aromatic diisocyanates, such as, e.g.,
4,4'-diphenylmethanediisocyanate, 2,4-toluene-diisocyanate,
naphthylene-1,5-diisocyanate, 1,3- and 1,4-phenylenediisocyanate,
and/or
[0055] b) aliphatic or cycloaliphatic diisocyanates, such as
hexamethylene-diisocyanate, 1,12-dodecanediisocyanate,
cyclobutane-1,3 -diisocyanate, cyclohexane 1,3- and
-1,4-diisocyanate,
1-isocyahato-3,3,5-trimethyl-5-isocyanatemethylcyclohexane, 2,4-
and 2,6-hexahydrotoluene-diisocyanate, hexahydro-1,3- and
-1,4-phenyldiisocyanate, perhydro-2,4' and
-4,4'diphenylmethane-diisocyanate, and
[0056] c) polyols having a molecular weight range from about 400 to
about 10,000, preferably from about 1000 to about 5000, such as
e.g. linear or branched
[0057] polybutadienes,
[0058] polycarbonates,
[0059] polycaprolactones,
[0060] polycaprolactams,
[0061] polyethers, e.g., polyethylene oxides, polypropylene oxides,
polybutylene oxides, polystyrene oxides, polyepichlorohydrines,
polytetrahydrofuranes,
[0062] polyesters, e.g., any condensation products of multivalent
alcohols (e.g. ethylene-glycol, propyleneglycol-1,2 and -1,3,
butylene-glycol-1,4 and -2,3, hexanediol-1,6, octanediol-1,8,
trimethylolpropane, neopentylglycol, glycerol, pentaerythritol,
quinitol, mannitol, sorbitol, methylglycoside, diethylene glycol,
polyethylene glycols, dipropylene glycol, polypropylene glycols
with multivalent carboxylic acids and/or carboxylic acid anhydrides
and/or carboxylic esters), e.g., succinic acid, adipic acid,
octanedioic acid, azelaic acid, sebacic acid, phthalic acid,
isophthalic acid, trimellitic acid, phthalic acid anhydride,
tetrahydrophthalic acid anhydride, tetrachlorophthalic acid
anhydride, glutaric acid anhydride, maleic acid anhydride, fumaric
acid, terephthalic acid-dimethylester and terephthalic
acid-bis-glycol-ester, each having terminal, primary and/or
secondary OH-groups, whereby the OH-functionality is preferably in
the range of around 2, and/or
[0063] d) short chain diols with terminal, primary and/or secondary
OH-groups, such as, e.g., ethylene-glycol,
bis-hexanediol-1,6,-propylene glycol, bis-hexapropylene glycol,
diethyleneglycol, bis-hexaethylene-glycol.
[0064] It is particularly preferred that one or more liquid
polyetherpolyol be utilized. Preferably the polyetherpolyol
includes an ethylene oxide end-capped triol and a propylene oxide
end-capped triol or a polypropylene glycol. It is also preferred
that the ethylene oxide end-capped triol preferably have a weight
average molecular weight of from about 4500 to about 5000 and that
the propylene oxide end-capped triol have a weight average
molecular weight of from about 150 to about 250. The polypropylene
glycol preferably has a weight average molecular weight of from
about 3500 to about 4500.
[0065] The polyurethane adhesive may be used to bond or seal the
following: any glass, especially glass plates for use in automotive
vehicles, composite glass plates, front walls of glass,
[0066] any metal, which may be varnished, metallized or otherwise
coated and/or pretreated, e.g., bodies of automotive vehicles,
[0067] any metal alloy, which may be varnished, metallized or
otherwise coated and/or pretreated, e.g., bodies of automotive
vehicles,
[0068] any plastic,
[0069] any construction material, especially stones, concrete,
mortar, road pavings, and any wood material.
[0070] In addition to the direct application of the polyurethane
adhesive, the adhesive composition may also be shaped, for
instance, with the aid of an applicator or extruder, to a profile
of any shape, such as, e.g., a cord, a ribbon, etc. For dimensional
stability there may be incorporated into the cord or the ribbon a
thread or a screen of any material. Such cords may be spirally
wound and may be stored in a water vapor barrier bag for later use.
These preformed cords may then be applied manually without the use
of machines to bond the above materials.
[0071] The following example shall illustrate the invention. The
parts mentioned herein are referred to by weight.
EXAMPLES
[0072] The following examples illustrate the preparation of the
polyurethane prepolymers according to the invention, adhesive
formulations prepared from the prepolymers and property
characteristics of the adhesives.
[0073] A. Formulation, Preparation Procedure and Characterization
of Polyurethane Prepolymers and Thixotropic Agent: TABLE-US-00001
1) Prepolymer I 68.585 parts Ethylene oxide (EO) end capped
glycerol poly(oxypropylene)triol w/ OH# .about.34-36 (EO-triol,
Arcol .RTM. E-448 from Bayer) 19.995 parts plasticizer diisodecyl
phthalate (Jayflex .RTM. DIDP from Exxon) 11.387 parts Methylene
bisphenyl diisocyanate (MDI, Mondur M from Bayer) 0.016 parts 33%
Triethylenediamine in Dipropyleneglycol (DABCO .RTM. 33 LV catalyst
from Air Products) 0.017 parts p-Toluensulfonyl isocyanate (PTSI
from VanChem Inc.)
[0074] The EO-triol, plasticizer and catalyst were combined in a
reactor and the mixture heated up to 60.degree. C. under vacuum.
MDI was then added and mixed at 60.degree. C. under vacuum until
the MDI melted. The mixture was then heated to 80.degree. C. and
the reaction continued at 80.degree. C. until the free NCO content
reached .about.2.5% by weight. PTSI was then added to stop further
reaction.
[0075] The prepolymer had a theoretical final free NCO content of
2.4% and a viscosity of 10,000-40,000 centipoise at 23.degree. C.
as measured with a Brookfield Viscometer HBTD by using a spindle
number 5 at 100 rpm. TABLE-US-00002 2) Prepolymer II 60.000 parts
Hexanediol adipate with OH number .about.34 (Polyester-diol,
Dynacoll .RTM. 7360 from Degussa) 10.000 parts plasticizer
diisodecyl phthalate (Jayflex .RTM. DIDP from Exxon) 18.000 parts
Polypropylene glycol with OH number .about.28 (PO-diol, Acclaim
.RTM. 4200 from Bayer) 12.000 parts Methylene bisphenyl
diisocyanate (MDI, Mondur M from Bayer)
[0076] The shredded polyester-diol, plasticizer and PO-diol were
combined in a reactor and the mixture heated up to 80.degree. C.
under vacuum until the polyester-diol melted. MDI was then added
and mixed at 80.degree. C. The mixture was held at 80.degree. C.
while stirring under vacuum until the free NCO content reached
.about.2.3% by weight. The prepolymer had a theoretical final free
NCO content of 2.1% and a viscosity of 20,000-40,000 centipoise at
60.degree. C. as measured with a Brookfield Viscometer HBTD by
using a spindle number 5 at 100 rpm. TABLE-US-00003 3) Prepolymer
III 64.282 parts Ethylene oxide (EO) end capped glycerol
poly(oxypropylene)triol w/ OH# .about.34-36 (EO-triol, Arcol .RTM.
E-448 from Bayer) 23.772 parts Polypropylene glycol with OH number
.about.28 (PO-diol, Acclaim .RTM. 4200 from Bayer) 0.016 parts
Dibutyltin dilaurate (DABCO .RTM. T-12 catalyst from Air Products)
11.930 parts Isophorone diisocyanate (IPDI, Desmodur I from
Bayer)
[0077] The EO-triol, PO-diol and catalyst were combined in a
reactor and the mixture heated up to 60.degree. C. under vacuum.
IPDI was then added and mixed at 60.degree. C. The mixture was then
heated to 80.degree. C. and the reaction continued at 80.degree. C.
until the free NCO content reached .about.2.2% by weight.
[0078] The prepolymer had a theoretical final free NCO content of
2.1% and a viscosity of 5,000-20,000 centipoise at 23.degree. C. as
measured with a Brookfield Viscometer HBTD by using a spindle
number 5 at 100 rpm. TABLE-US-00004 4) Prepolymer IV 27.480 parts
Ethylene oxide (EO) end capped glycerol poly(oxypropylene)triol W/
OH# .about.34-36 (EO-triol, Arcol .RTM. E-448 from Bayer) 0.480
parts Hexanediol adipate with OH number .about.34 (Polyester-diol
Dynacoll .RTM. 7360 from Degussa) 40.760 parts A blended
hexanediol-neopentyl glycol adipate with OH number .about.34
(Blended polyester-diol Millester .RTM. 9-35 from Polyurethane
Specialties Company, Inc.) 20.000 parts plasticizer diisodecyl
phthalate (Jayflex .RTM. DIDP from Exxon) 11.280 parts Methylene
bisphenyl diisocyanate (MDI, Mondur M from Bayer)
[0079] The EO-triol, the shredded polyester-diol and blended
polyester-diol and plasticizer were combined in a reactor and the
mixture heated up to 80.degree. C. under vacuum until the
polyester-diol melted. MDI was then added and mixed at 80.degree.
C. The mixture was held at 80.degree. C. while stirring under
vacuum until the free NCO content reached .about.2.1% by weight.
The prepolymer had a theoretical final free NCO content of 2.0% and
a viscosity of 100,000-300,000 centipoise at 23.degree. C. as
measured with a Brookfield Viscometer HBTD by using a spindle
number 5 at 100 rpm. TABLE-US-00005 5) Prepolymer V 30.000 parts
Ethylene oxide (EO) end capped glycerol poly(oxypropylene)triol w/
OH# .about.34-36 (EO-triol, Arcol .RTM. E-448 from Bayer) 0.200
parts Glycerol poly(oxypropylene)triol w/ OH# .about.1052
(PO-triol, Multranol .RTM. 9133 from Bayer) 0.500 parts Hexanediol
adipate with OH number .about.34 (Polyester-diol, Dynacoll .RTM.
7360 from Degussa) 37.350 parts A blended hexanediol-neopentyl
glycol adipate with OH number .about.34 (Blended polyester-diol,
Millester .RTM. 9-35 from Polyurethane Specialties Company, Inc.)
20.000 parts plasticizer diisodecyl phthalate (Jayflex .RTM. DIDP
from Exxon) 11.950 parts Methylene bisphenyl diisocyanate (MDI,
Mondur M from Bayer)
[0080] The EO-triol, PO-triol, the shredded polyester-diol and
blended polyester-diol and plasticizer were combined in a reactor
and the mixture heated up to 80.degree. C. under vacuum until the
polyester-diol melted. MDI was then added and mixed at 80.degree.
C. The mixture was held at 80.degree. C. while stirring under
vacuum until the free NCO content reached .about.2.1% by weight.
The prepolymer had a theoretical final free NCO of 2.0% and a
viscosity of 100,000-300,000 centipoise at 23.degree. C. as
measured with a Brookfield Viscometer HBTD by using a spindle
number 5 at 100 rpm. TABLE-US-00006 6) Prepolymer VI 51.826 parts
Ethylene oxide (EO) end capped glycerol poly(oxypropylene)triol w/
OH# .about.34-36 (EO-triol, Arcol .RTM. E-448 from Bayer) 25.913
parts Polypropylene glycol with OH number .about.28 (PO-diol,
Acclaim .RTM. 4200 from Bayer) 10.000 parts plasticizer diisodecyl
phthalate (Jayflex .RTM. DIDP from Exxon) 12.205 parts Methylene
bisphenyl diisocyanate (MDI, Mondur M from Bayer) 0.003 parts 33%
Triethylenediamine in Dipropyleneglycol (DABCO .RTM. 33 LV catalyst
from Air Products) 0.010 parts p-Toluensulfonyl isocyanate (PTSI
from VanChem Inc.)
[0081] The EO-triol, PO-diol, plasticizer and catalyst were
combined in a reactor and the mixture heated up to 60.degree. C.
under vacuum. MDI was then added and mixed at 60.degree. C. under
vacuum until the MDI melted. The mixture was then heated to
80.degree. C. and the reaction continued at 80.degree. C. until the
free NCO content reached .about.2.4% by weight. PTSI was then added
to stop further reaction.
[0082] The prepolymer had a theoretical final free NCO content of
2.3% and a viscosity of 18,000-40,000 centipoise at 23.degree. C.
as measured with a Brookfield Viscometer HBTD by using a spindle
number 5 at 100 rpm. TABLE-US-00007 7) Prepolymer VII 20.000 parts
Hexanediol adipate with OH number .about.34 (Polyester-diol,
Dynacoll .RTM. 7360 from Degussa) 80.000 parts Copolyester-diol
with OH number .about.22 (Oxyflex S 1151-22 from Oxydental
Chemicals) 13.572 parts Methylene bisphenyl diisocyanate (MDI,
Mondur M from Bayer)
[0083] TABLE-US-00008 8) Prepolymer VIII 22.000 parts
Copolyester-diol with OH number .about.21 (Copolyester-diol,
Dynacoll .RTM. 7250 from Degussa) 14.000 parts Copolyester-diol
with OH number .about.31 (Copolyester-diol, Dynacoll .RTM. 7230
from Degussa) 39.000 parts Copolyester-diol with OH number
.about.42 (Copolyester-diol, Dynacoll .RTM. 7150 from Degussa)
25.000 parts Copolyester-diol with OH number .about.62 (Oxyflex S
1015-62 from Oxydental Chemicals) 17.858 parts Methylene bisphenyl
diisocyanate (MDI, Mondur M from Bayer)
[0084] TABLE-US-00009 9) Thixotropic agent 981 parts Methylene
bisphenyl diisocyanate (MDI, Mondur M from Bayer) 6418 parts
plasticizer diisodecyl phthalate (Jayflex .RTM. DIDP from Exxon)
518 parts N-butylamine 12.5 parts N-methyl-2-pyrrolidone
[0085] B. Formulation of Polyurethane Catalyst Solutions:
TABLE-US-00010 1) Catalyst Solution I 78.500 parts plasticizer
diisodecyl phthalate (Jayflex .RTM. DIDP from Exxon) 8.250 parts
Dimorpholinodiethylether (Jeffcat DMDEE from Huntsman) 12.250 parts
Dimorpholino substituted polyethylene glycol (Polymeg DMDEE or
DMPEG from Huntsman) 1.000 parts Dibutyltin dilaurate (DABCO .RTM.
T-12 catalyst from Air Products)
[0086] TABLE-US-00011 2) Catalyst Solution II 55.800 parts
plasticizer diisodecyl phthalate (Jayflex .RTM. DIDP from Exxon)
6.000 parts Tetramethyl dimorpholinodiethylether (TM-DMDEE, U-Cat
651M from SAN-APRO) 37.000 parts Dimorpholino substituted
polyethylene glycol (Polymeg DMDEE or DMPEG from Huntsman) 1.200
parts Dibutyltin dilaurate (DABCO .RTM. T-12 catalyst from Air
Products)
[0087] TABLE-US-00012 3) Catalyst Solution III 45.800 parts
plasticizer diisodecyl phthalate (Jayflex .RTM. DIDP from Exxon)
9.900 parts Tetramethyl dimorpholinodiethylether (TM-DMDEE, U-Cat
651M from SAN-APRO) 42.000 parts Dimorpholino substituted
polyethylene glycol (Polymeg DMDEE or DMPEG from Huntsman) 2.300
parts Dibutyltin dilaurate (DABCO .RTM. T-12 catalyst from Air
Products)
[0088] TABLE-US-00013 4) Catalyst Solution IV 51.500 parts
plasticizer diisodecyl phthalate (Jayflex@ DIDP from Exxon) 4.000
parts. Tetramethyl dimorpholinodiethylether (TM-DMDEE, U-Cat 651M
from SAN-APRO) 42.000 parts Dimorpholino substituted polyethylene
glycol (Polymeg DMDEE or DMPEG from Huntsman) 2.500 parts
Dibutyltin dilaurate (DABCO .RTM. T-12 catalyst from Air
Products)
[0089] C. Formulation and Preparation Procedure of Polyurethane
Adhesives: TABLE-US-00014 1) Adhesive I 32.951 parts Prepolymer I
described above 11.200 parts Prepolymer III described above 14.621
parts Polyvinyl chloride powder (PVC, EH-250 from Kaneka) 8.344
parts Thixotropic agent described above 0.257 parts
p-Toluensulfonyl isocyanate (PSTI from VanChem Inc.) 16.321 parts
Carbon Black powder (Printex 60 from Degussa) 5.791 parts
Prepolymer II described above 8.305 parts Plasticizer diisodecyl
phthalate (Jayflex .RTM. DIDP from Exxon) 0.298 parts Epoxysilane
adhesion promoter (Silane A-187 from Osi) 1.912 parts Catalyst
solution H described above
[0090] The DIDP, Prepolymer I, Prepolymer DI, PVC powders and
Thixotropic agent were placed into a vacuum mixer and mixed under
vacuum for 5 minutes. PSTI was then added and mixed under vacuum
for 5 minutes. Carbon Black powder was next added and mixed under
vacuum until the temperature reached 60.degree. C. Previously
melted Prepolymer II was then added and mixed under vacuum for 10
minutes. Silane was subsequently added and mixed under vacuum for 5
minutes, followed by the addition of Catalyst solution II and
further mixing under vacuum for 5 minutes. TABLE-US-00015 2)
Adhesive II 59.550 parts Prepolymer IV described above 14.470 parts
Polyvinyl chloride powder (PVC, EH-250 from Kaneka) 8.240 parts
Thixotropic agent described above 0.500 parts p-Toluensulfonyl
isocyanate (PSTI from VanChem Inc.) 15.070 parts Carbon Black
powder (Printex 60 from Degussa) 0.300 parts Epoxysilane adhesion
promoter (Silane A-187 from Osi) 1.870 parts Catalyst solution III
described above
[0091] The Prepolymer IV, PVC powder and Thixotropic agent were
placed into a vacuum mixer and mixed under vacuum for 5 minutes.
PSTI was then added and mixed under vacuum for 5 minutes. Carbon
Black powder was next added and mixed under vacuum for 10 minutes.
Silane was subsequently added and mixed under vacuum for 5 minutes,
followed by the addition of Catalyst solution III and further
mixing under vacuum for 5 minutes. TABLE-US-00016 3) Adhesive III
53.000 parts Prepolymer IV described above 4.330 parts Plasticizer
diisodecylphthalate (Jayflex .RTM. DIDP from Exxon) 17.000 parts
Clay powder (Satintone Whitetex from Engelhard) 0.500 parts
p-Toluensulfonyl isocyanate (PSTI from VanChem Inc.) 23.000 parts
Carbon Black powder (Printex 60 from Degussa) 0.300 parts
Epoxysilane adhesion promoter (Silane A-187 from Osi) 1.870 parts
Catalyst solution III described above
[0092] The Prepolymer IV, DIDP and Whitetex clay powder were placed
into a vacuum mixer and mixed under vacuum for 5 minutes. PSTI was
then added and mixed under vacuum for.5 minutes. Carbon Black
powder was next added and mixed under vacuum for 10 minutes. Silane
was subsequently added and mixed under vacuum for 5 minutes,
followed by the addition of Catalyst solution III and further
mixing under vacuum for 5 minutes. TABLE-US-00017 2) Adhesive IV
59.550 parts Prepolymer V described above 14.470 parts Polyvinyl
chloride powder (PVC, EH-250 from Kaneka) 8.240 parts Thixotropic
agent described above 0.500 parts p-Toluensulfonyl isocyanate (PSTI
from VanChem Inc.) 15.070 parts Carbon Black powder (Printex 60
from Degussa) 0.300 parts Epoxysilane adhesion promoter (Silane
A-187 from Osi) 1.870 parts Catalyst solution IV described
above
[0093] The Prepolymer V, PVC powder and Thixotropic agent were
placed into a vacuum mixer and mixed under vacuum for 5 minutes.
PTSI was then added and mixed under vacuum for 5 minutes. Carbon
Black powder was next added and mixed under vacuum for 10 minutes.
Silane was subsequently added and mixed under vacuum for 5 minutes,
followed by the addition of Catalyst solution IV and further mixing
under vacuum for 5 minutes. TABLE-US-00018 3) Adhesive V 8.657
parts Prepolymer III described above 13.607 parts Plasticizer
diisodecyl phthalate (Jayflex .RTM. DIDP from Exxon) 31.570 parts
Prepolymer VI described above 0.209 parts Homopolymer of
Hexamethylene Diisocyanate (Polymeric HDI, Desmodur N 100 from
Bayer) 1.771 parts Fumed silicate powder (Aerosil .RTM. R972 from
Degussa) 13.225 parts Clay powder (Satintone Whitetex from
Engelhard) 5.302 parts Low conductive carbon black powder (Monarch
120 from Cabot) 13.66 parts Carbon black powder (Elftex 125 from
Cabot) 0.500 parts Prepolymer VII described above 9.500 parts
Prepolymer VII described above 2.000 parts Catalyst solution I
[0094] The Prepolymer HI, DIDP, Prepolymer VI and Desmodur N 100
were placed into a vacuum mixer, and mixed under vacuum to
55.degree. C. Aerosil and Whitetex clay powders were then added and
mixed under vacuum to a homogenous mass. Carbon Black powder was
next added and mixed under vacuum for 10 minutes. The fineness was
then checked and, when satisfactory, previously melted Prepolymer
VII and Prepolymer VIII were added and the mixture heated up to
100.degree. C. and mixed under vacuum 10 minutes. Catalyst Solution
1 was then added and mixed under vacuum for 5 minutes.
4) Adhesive VI
[0095] SikaTack.RTM. Ultrafast II (a fast curing, one component,
polyurethane wind-shield adhesive available from Sika Industry,
USA).
D. Green Strength or Early Tensile Strength of Polyurethane
Adhesives:
[0096] Green strength or early tensile strength properties of
polyurethane adhesive compositions were measured according to the
following procedure:
[0097] Adhesive materials in cartridges were placed in an oven at
80.degree. C. for a period of one hour prior to use. Glass pieces
were cleaned with Burco Glass Cleaner. After 10 minutes of flash
time, Sika-Aktivator.RTM. (a moisture sensitive liquid for the
pre-treatment of surfaces to improve adhesion available from Sika
Industry, USA) was applied using a wipe on wipe off procedure. The
Sika-Aktivator.RTM. was allowed to flash for 10 minutes. Next, the
adhesive was applied hot at 80.degree. C. to the glass and top
pieces of the same size were placed on top of the adhesive bead and
compressed to a thickness of 4 mm. The test specimens were then
placed in respective environmental chambers at designated climate
condition (temperature and humidity). Samples were taken after 1
hour to test force on gauge (FOG) at a test speed (strain rate) of
1 meter/second. After testing, the bond-line of each sample was
measured, the area of fracture was calculated, and the green
strength calculated (FOG/unit area). The adhesive in the same
cartridge was measured five times to get an average number for the
green strength. The results of these tests are shown in the Table
I. TABLE-US-00019 TABLE I Green strengths for Polyurethane
Adhesives at Various Cure Conditions (measured at 1 meter/second
strain rate, ASTM D412) Tensile Strength at break (Peak Stress,
MPa) Cure Conditions (Temperature, .degree. C.; % relative
humidity) Adhesive 1 hr @ 5.degree. C.; 1 hr @ 23.degree. C.; 1 hr
@ 35.degree. C.; Formulation 50% rh 50% r.h. 20% r.h. I 1.3 0.8 0.5
II 2.9 0.9 0.8 III 3.0 1.1 0.8 IV 2.9 1.1 1.0 V 1.6 1.0 0.7 VI 0.9
0.7 0.5
E. Compression Properties of Polyurethane Adhesives:
[0098] Compression force measurements were recorded on adhesive
beads having a triangular cross-sectional shape. The beads were
applied along the length of one flat test plate (typically glass,
although other materials may be used) having dimensions of 100 mm
length, 40 mm width and 4 mm thickness using a triangular bead
applicator. The adhesive bead had an original height of 10 mm, a
base width of 8 mm and a length of 100 mm. A second test plate was
placed on top of the adhesive bead such that the faces of the two
test plates were parallel and the plates were aligned in
orientation. The plates were then compressed at a constant rate of
190 mm/min and the compression force recorded, typically at
5.degree. C. and after 10 minutes from the application of the
adhesive to the first test plate. The compression force per unit
area was calculated by measuring the cross-sectional area of the
compressed adhesive layer after the bead height had been compressed
to 5 mm and dividing the force by the bead area. The following
compression force tests were performed for adhesive samples cured
for 10 minutes at 5.degree. C. by compressing the samples from 10
mm to 5 mm at a rate of 5 190 min/min.: TABLE-US-00020 TABLE II
Compression Force of Polyurethane Adhesives at 5.degree. C. after
10 minutes Adhesive Sample Formulation Compression Force (MPa) I
0.10 II 0.09 III 0.12 IV 0.17 V 0.11 VI 0.09
[0099] While the invention has been described in terms of preferred
embodiments, the skilled artisan will appreciate that various
modifications, substitutions, omissions and changes may be made
without departing from the spirit thereof. Accordingly, it is
intended that the scope of the present invention be limited solely
by the scope of the following claims, including equivalents
thereof.
* * * * *