U.S. patent application number 16/152599 was filed with the patent office on 2019-01-31 for silylated polyurethanes, their preparation and use.
The applicant listed for this patent is Henkel AG & Co. KGaA. Invention is credited to Ralf Baetzgen, David Briers, Jan-Erik Damke, Johann Klein.
Application Number | 20190031812 16/152599 |
Document ID | / |
Family ID | 52736839 |
Filed Date | 2019-01-31 |
United States Patent
Application |
20190031812 |
Kind Code |
A1 |
Baetzgen; Ralf ; et
al. |
January 31, 2019 |
Silylated Polyurethanes, Their Preparation and Use
Abstract
A silylated polyurethane obtainable by a process comprising the
following steps: (a) reacting at least one polyol with at least one
triisocyanate to form a hydroxyl-terminated polyurethane
prepolymer, and (b) reacting said polyurethane prepolymer with at
least one isocyanatosilane of the formula (1):
OCN--R--Si--(X).sub.m(R.sup.1).sub.3-m, wherein m is 0, 1 or 2,
each R.sup.1 is independently from each other a hydroxyl group, an
alkoxy group having 1 to 10 carbon atoms, an acyloxy group having 1
to 10 carbon atoms, or --OCH(R.sup.2)COOR.sup.3, wherein R.sup.2 is
hydrogen or an alkyl group having 1 to 4 carbon atoms and R.sup.3
is a straight-chain or branched alkyl group having 1 to 8 carbon
atoms, each X is independently from each other and optionally
substituted hydrocarbon group having 1 to 10 carbon atoms, which
can be interrupted by at least one heteroatom, and R is a
difunctional organic group, to endcap the hydroxyl groups on said
prepolymer with said isocyanatosilane. The silylated polyurethanes
are suitable for use in a preparation as an adhesive, sealant, or
coating agent.
Inventors: |
Baetzgen; Ralf;
(Duesseldorf, DE) ; Damke; Jan-Erik; (Duesseldorf,
DE) ; Briers; David; (Hasselt, BE) ; Klein;
Johann; (Duesseldorf, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Henkel AG & Co. KGaA |
Duesseldorf |
|
DE |
|
|
Family ID: |
52736839 |
Appl. No.: |
16/152599 |
Filed: |
October 5, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15697499 |
Sep 7, 2017 |
10118984 |
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16152599 |
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PCT/EP2016/055005 |
Mar 9, 2016 |
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15697499 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08G 18/227 20130101;
C08G 18/718 20130101; C08G 18/10 20130101; C08G 18/4825 20130101;
C08G 18/792 20130101; C08G 18/10 20130101; C08G 18/718
20130101 |
International
Class: |
C08G 18/10 20060101
C08G018/10; C08G 18/79 20060101 C08G018/79; C08G 18/48 20060101
C08G018/48; C08G 18/22 20060101 C08G018/22; C08G 18/71 20060101
C08G018/71 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 11, 2015 |
EP |
15158615.3 |
Claims
1. A silylated polyurethane obtained by a process comprising the
following steps: (a) reacting at least one polyol with at least one
triisocyanate to form a hydroxyl-terminated polyurethane
prepolymer; and (b) reacting the hydroxyl-terminated polyurethane
prepolymer with at least one isocyanatosilane of formula (1) to
endcap the hydroxyl groups on the hydroxyl-terminated polyurethane
prepolymer with the isocyanatosilane,
OCN--R--Si--(X).sub.m(R.sup.1).sub.3-m (1) wherein m is 0, 1 or 2,
each R.sup.1 is independently from each other a hydroxyl group, an
alkoxy group having 1 to 10 carbon atoms, an acyloxy group having 1
to 10 carbon atoms, or --OCH(R.sup.2)COOR.sup.3, wherein R.sup.2 is
hydrogen or an alkyl group having 1 to 4 carbon atoms and R.sup.3
is a straight-chain or branched alkyl group having 1 to 8 carbon
atoms, each X is independently from each other an optionally
substituted hydrocarbon group having 1 to 10 carbon atoms, which
can be interrupted by at least one heteroatom, and R is a
difunctional organic group.
2. The silylated polyurethane according to claim 1, wherein a molar
ratio of the NCO groups of the triisocyanate to hydroxyl groups of
the polyol is from 0.05 to 0.45.
3. The silylated polyurethane according to claim 1, wherein said
polyol is a polyether polyol.
4. The silylated polyurethane according to claim 1, wherein said
polyol has a number average molecular weight of from 500 to 20,000
g/mol.
5. The silylated polyurethane according to claim 1, wherein said
triisocyanate is derived from HDI, TDI, MDI, PDI, IPDI, or mixtures
thereof.
6. The silylated polyurethane according to claim 1, wherein said
isocyanatosilane is selected from the group consisting of
3-isocyanatopropyltrimethoxysilane,
2-isocyanatoisopropyltrimethoxysilane,
4-isocyanato-n-butyltrimethoxysilane,
2-isocyanato-1,1-dimethylethyltrimethoxysilane,
1-isocyanatomethyltrimethoxysilane,
3-isocyanatopropyltriethoxysilane,
2-isocyanato-2-methylethyltriethoxysilane,
4-isocyanatobutyltriethoxysilane,
2-isocyanato-1,1-dimethylethyltriethoxysilane,
1-isocyanatomethyltriethoxysilane,
3-isocyanatopropylmethyldimethoxysilane,
3-isocyanatopropyldimethylmethoxysilane,
3-isocyanatopropylphenylmethylmethoxysilane,
1-isocyanatomethylmethyldimethoxysilane,
3-isocyanatopropylethyldiethoxysilane,
3-isocyanatopropylmethyldiethoxysilane,
1-isocyanatomethylmethyldiethoxysilane, and mixtures thereof.
7. The silylated polyurethane according to claim 1, wherein said
process comprises further step of adding a catalyst.
8. A process for preparing a silylated polyurethane comprising the
following steps: (a) reacting at least one polyol with at least one
triisocyanate to form a hydroxyl-terminated polyurethane
prepolymer; and (b) reacting the hydroxyl-terminated polyurethane
prepolymer with at least one isocyanatosilane of formula (1) to
endcap the hydroxyl groups on the hydroxyl-terminated polyurethane
prepolymer with the isocyanatosilane,
OCN--R--Si--(X).sub.m(R.sup.1).sub.3-m (1) wherein m is 0, 1 or 2,
each R.sup.1 is independently from each other a hydroxyl group, an
alkoxy group having 1 to 10 carbon atoms, an acyloxy group having 1
to 10 carbon atoms, or --OCH(R.sup.2)COOR.sup.3, wherein R.sup.2 is
hydrogen or an alkyl group having 1 to 4 carbon atoms and R.sup.3
is a straight-chain or branched alkyl group having 1 to 8 carbon
atoms, each X is independently from each other an optionally
substituted hydrocarbon group having 1 to 10 carbon atoms, which
can be interrupted by at least one heteroatom, and R is a
difunctional organic group.
9. An adhesive, sealant, or coating composition comprising the
silylated polyurethane according to claim 1.
10. A silylated polyurethane that is the reaction product of a
mixture comprising: (a) the hydroxyl terminated polyurethane
prepolymer reaction product of a mixture comprising at least one
polyol and at least one triisocyanate; and (b) at least one
isocyanatosilane of formula (1)
OCN--R--Si--(X).sub.m(R.sup.1).sub.3-m (1) wherein m is 0, 1 or 2,
each R.sup.1 is independently from each other a hydroxyl group, an
alkoxy group having 1 to 10 carbon atoms, an acyloxy group having 1
to 10 carbon atoms, or --OCH(R.sup.2)COOR.sup.3, wherein R.sup.2 is
hydrogen or an alkyl group having 1 to 4 carbon atoms and R.sup.3
is a straight-chain or branched alkyl group having 1 to 8 carbon
atoms, each X is independently from each other an optionally
substituted hydrocarbon group having 1 to 10 carbon atoms, which
can be interrupted by at least one heteroatom, and R is a
difunctional organic group.
Description
[0001] The present invention relates to silylated polyurethanes,
their preparation and their use in adhesives, sealants, and in
coating compositions.
[0002] Polymer systems that possess reactive alkoxysilyl groups are
known. In the presence of atmospheric moisture these
alkoxysilane-terminated polymers are capable, already at room
temperature, of condensing with one another with release of the
alkoxy groups. What forms in this context, depending on the
concentration of alkoxysilyl groups and their configuration, are
principally long-chain polymers (thermoplastics), relatively
wide-mesh three-dimensional networks (elastomers), or highly
crosslinked systems (thermosetting plastics).
[0003] The polymers generally comprise an organic backbone that
carries alkoxysilyl groups at the ends. The organic backbone can
involve, for example, polyurethanes, polyesters, polyethers,
etc.
[0004] One-component, moisture-curing adhesives and sealants have
played for years a significant role in numerous technical
applications. In addition to the polyurethane adhesives and
sealants having free isocyanate groups, and the traditional
silicone adhesives and sealants based on dimethylpolysiloxanes, the
so-called modified silane adhesives and sealants have also been
increasingly used recently. In this latter group, the main
constituent of the polymer backbone is a polyether, and the
reactive and crosslinkable terminal groups are alkoxysilyl groups.
The modified silane adhesives and sealants have the advantage, as
compared with the polyurethane adhesives and sealants, of being
free of isocyanate groups, in particular of monomeric
diisocyanates; they are also notable for a broad adhesion spectrum
to a plurality of substrates without surface pretreatment using
primers.
[0005] U.S. Pat. No. 4,222,925 A and U.S. Pat. No. 3,979,344 A
describe siloxane-terminated organic sealant compositions, curable
already at room temperature, based on reaction products of
isocyanate-terminated polyurethane prepolymers with
3-aminopropyltrimethoxysilane or 2-aminoethyl- or
3-aminopropylmethoxysilane to yield isocyanate-free
siloxane-terminated prepolymers. Adhesives and sealants based on
these prepolymers have unsatisfactory mechanical properties,
however, especially in terms of their elongation and breaking
strength.
[0006] The methods set forth below for the manufacture of
silane-terminated prepolymers based on polyethers have already been
described: [0007] Copolymerization of unsaturated monomers with
ones that comprise alkoxysilyl groups, for example
vinyltrimethoxysilane. [0008] Grafting unsaturated monomers, such
as vinyltrimethoxysilane, onto thermoplastics such as polyethylene.
[0009] Hydroxyfunctional polyethers are converted in an ether
synthesis, using unsaturated chlorine compounds, e.g. allyl
chloride, into polyethers having terminal olefinic double bounds,
which in turn are reacted with hydrosilane compounds that have
hydrolyzable groups, for example HSi(OCH.sub.3).sub.3, in a
hydrosilylation reaction under the catalytic influence of, for
example, transition metal compounds of the eighth group, to yield
silane-terminated polyethers. [0010] In another method, the
polyethers containing olefinically unsaturated groups are reacted
with a mercaptosilane such as, for example,
3-mercaptopropyltrialkoxysilane. [0011] In a further method,
firstly hydroxyl-group-containing polyethers are reacted with di-
or polyisocyanates, which are then in turn reacted with
aminofunctional silanes or mercaptofunctional silanes to yield
silane-terminated prepolymers. [0012] A further possibility
provides for the reaction of hydroxyfunctional polyethers with
isocyanatofunctional silanes such as, for example,
3-isocyanatopropyltrimethoxysilane.
[0013] These manufacturing methods, and the use of the
aforementioned silane-terminated prepolymers in adhesive/sealant
applications, are recited e.g. in the following patent documents:
U.S. Pat. No. 3,971,751 A, EP-A-70475, DE-A-19849817, U.S. Pat. No.
6,124,387 A, U.S. Pat. No. 5,990,257 A, U.S. Pat. No. 4,960,844 A,
U.S. Pat. No. 3,979,344 A, U.S. Pat. No. 3,632,557 A, DE-A-4029504,
EP-A-601021, or EP-A-370464.
[0014] EP 0931800 A1 describes the manufacture of silylated
polyurethanes by reacting a polyol component having a terminal
unsaturation of less than 0.02 meq/g with a diisocyanate to yield a
hydroxyl-terminated prepolymer, and then reacting that with an
isocyanatosilane of the formula
OCN--R--Si--(X).sub.m(--OR.sup.1).sub.3-m, where m is 0, 1, or 2
and each R.sup.1 residue is an alkyl group having 1 to 4 carbon
atoms and R is a difunctional organic group. According to the
teaching of this document, such silylated polyurethanes exhibit a
superior combination of mechanical properties, and cure in
reasonable amounts of time to yield a low-tack sealant without
exhibiting excessive viscosity.
[0015] WO 2009/071542 A1 describes a method for preparing a
silylated polyurethane, comprising reacting at least one polyol
compound having a molecular weight of 4,000 to 30,000 g/mol and at
least one monofunctional compound with regard to isocyanates with
at least one diisocyanate, in a stoichiometric excess of the sum of
the polyol compound(s) and monofunctional compound(s) relative to
the diisocyanate compound(s), whereby a hydroxyl-terminated
polyurethane prepolymer is formed which is subsequently reacted
with isocyanatosilane.
[0016] A need still exists for compositions based on silylated
polyurethanes for use in adhesives and sealants that exhibit better
performance, in particular, curing speed and mechanical strength
after curing, and at the same time show acceptable viscosity,
allowing the compositions to be easily applied. The object of the
present invention is therefore to provide silylated polyurethanes
and respective compositions having improved curing speed while
having acceptable mechanical strength and viscosity.
[0017] The manner in which the object is achieved by the invention
may be gathered from the Claims. It contains essentially of a
silylated polyurethane obtainable by a process comprising the
following steps: [0018] (a) reacting at least one polyol with at
least one triisocyanate to form a hydroxyl-terminated polyurethane
prepolymer; and [0019] (b) reacting said polyurethane prepolymer
with at least one isocyanatosilane of the formula (1)
[0019] OCN--R--Si--(X).sub.m(R.sup.1).sub.3-m (1) [0020] wherein
[0021] m is 0, 1 or 2, [0022] each R.sup.1 is independently from
each other a hydroxyl group, an alkoxy group having 1 to 10 carbon
atoms, an acyloxy group having 1 to 10 carbon atoms, or
--OCH(R.sup.2)COOR.sup.3, wherein R.sup.2 is hydrogen or an alkyl
group having 1 to 4 carbon atoms and R.sup.3 is a straight-chain or
branched alkyl group having 1 to 8 carbon atoms, [0023] each X is
independently from each other and optionally substituted
hydrocarbon group having 1 to 10 carbon atoms, which can be
interrupted by at least one heteroatom, and [0024] R is a
difunctional organic group, [0025] to endcap the hydroxyl groups on
said prepolymer with said isocyanatosilane.
[0026] According to the present invention, a hydroxyl-terminated
polyurethane prepolymer is obtained by reacting at least one polyol
with at least one triisocyanate.
[0027] A "polyol" is understood for purpose of the present
invention as a polymer having at least two hydroxyl groups. In
principle, a large number of polymers carrying at least two
hydroxyl groups, such as polyester polyols, polycaprolactones,
polybutadienes or polyisoprenes as well as hydrogenation products
thereof, or also polyacrylates or polymethacrylates, can be used as
polyol compounds. Mixtures of different polyol compounds can also
be used.
[0028] According to the present invention, a polyether polyol is
preferably used as the polyol. A "polyether" is understood for
purpose of the present invention as a polymer whose repeating unit
contains ether functionalities C--O--C in the main chain. Polymers
having lateral ether groups, such as cellulose ethers, starch
ethers, and vinyl ether polymers, as well as polyacetals, are
therefore not covered by this definition.
[0029] Polymers which contain polyethers as backbone have a
flexible and elastic structure with which compositions that have
outstanding elastic properties can be manufactured. Polyethers are
not only flexible in their backbone, but also strong at the same
time. Thus, for example, polyethers (in contrast to e.g.,
polyesters) are not attacked or decomposed by water and
bacteria.
[0030] In a preferred embodiment of the present invention, the
polyol is a polyalkylene oxide, and more preferably polyethylene
oxide and/or polypropylene oxide.
[0031] Particularly advantageous viscoelastic properties can be
achieved if polyethers having a narrow molecular weight
distribution, and thus a low polydispersity are used as polymer
backbones. These can be prepared, for example, by so-called double
metal cyanide (DMC) catalysis. Polyethers prepared in this way are
notable for a particularly narrow molecular weight distribution, a
high average molecular weight, and a very small number of double
bonds at the ends of the polymer chains.
[0032] In a specific embodiment of the present invention, the
polyol is a polyether polyol having a polydispersity PD of less
than 3, preferably less than 1.7, more preferably less than 1.5,
and most preferably less than 1.3.
[0033] According to the present invention, the number average
molecular weight M.sub.n of the polymer backbone of the polyol
compounds is from 500 to 20,000 g/mol (daltons), preferably from
2,000 to 18,000 g/mol, and most preferably 2,000 to 12,000 g/mol,
the terminal unsaturation being less than 0.05 meq/g, preferably
less than 0.04 meq/g, and more preferably less than 0.02 meq/g.
[0034] These molecular weights are particularly advantageous
because these polyols are readily available commercially and the
resulting polyurethanes or the compositions based thereon have a
good balance of viscosity (ease of processing) prior to curing and
strength and elasticity after curing.
[0035] The number average molecular weight M.sub.n, as well as the
weight average molecular weight M.sub.w, is determined by gel
permeation chromatography (GPC, also known as SEC). This method is
known to one skilled in the art. The polydispersity is derived from
the average molecular weights M.sub.w and M.sub.n. It is calculated
as PD=M.sub.w/M.sub.n.
[0036] The ratio M.sub.w/M.sub.n, also referred to as
"polydispersity," indicates the width of the molecular weight
distribution and thus the differing degrees of polymerization of
the individual chains in polydisperse polymers. For many polymers
and polycondensates, the applicable polydispersity value is
approximately 2. Strict monodispersity would exist for a value of
1. A low polydispersity (for example, less than 1.5) indicates a
comparatively narrow molecular weight distribution and thus the
specific expression of properties associated with molecular weight,
for example viscosity.
[0037] The triisocyanates suitable to convert the polyol compound
into a hydroxyl-terminated polyurethane prepolymer can be derived
from diisocyanates. Preferably, the triisocyanates are derived from
HDI, TDI, MDI, PDI or IPDI, or mixtures thereof. In particular,
following triisocyanates are most preferred.
##STR00001##
[0038] According to the present invention, a stoichiometric excess
of the hydroxyl groups of the polyol compound(s) with respect to
the NCO groups of the triisocyanate(s) or mixture of triisocyanates
is used. The preferred molar ratio of the NCO groups to hydroxyl
groups is from 0.05 to 0.45, preferably from 0.1 to 0.45, and more
preferably from 0.2 to 0.45. This ensures that a polyurethane
prepolymer having terminal hydroxyl groups is formed in step (a)
according to the present invention.
[0039] The polyurethane prepolymer having terminal hydroxyl groups
that is thereby formed is then reacted with at least one
isocyanatosilane of formula (1):
OCN--R--Si--(X).sub.m(R.sup.1).sub.3-m,
to endcap the hydroxyl groups on said prepolymer with said
isocyanatosilane. In formula (1) m is 0, 1 or 2, preferably 0 or
1.
[0040] Each R.sup.1 is independently from each other a hydroxyl
group, an alkoxy group having 1 to 10 carbon atoms, an acyloxy
group having 1 to 10 carbon atoms, or --OCH(R.sup.2)COOR.sup.3,
wherein R.sup.2 is hydrogen or an alkyl group having 1 to 4 carbon
atoms and R.sup.3 is a straight-chain or branched alkyl group
having 1 to 8 carbon atoms.
[0041] In a preferred embodiment of the present invention, each
R.sup.1 is independently of each other an alkoxy or acyloxy group
having 1 to 4 carbon atoms. More preferably, each R.sup.1 is
independently of each other a methoxy or ethoxy group, particularly
a methoxy group. Methoxy and ethoxy groups, as comparatively small
hydrolyzable groups with low steric bulk, are very reactive and
thus enable a rapid cure even with low use of catalyst. They are
therefore of particular interest for systems in which a rapid cure
is desired, such as e.g. in adhesives requiring high initial
adhesion. Particularly preferably, methoxy group is used. The
methoxy group displays the greatest reactivity among the alkoxy
groups. Silyl groups of this type can therefore be used when a
particularly rapid cure is desired. Higher aliphatic residues, such
as ethoxy, already bring about lower reactivity of the terminal
alkoxysilyl group compared with methoxy groups and can
advantageously be used to develop gradual crosslinking rates.
[0042] In another preferred embodiment of the present invention,
R.sup.1 is --OCH(R.sup.2)COOR.sup.3, wherein preferably R.sup.2 is
methyl group and R.sup.3 is a straight-chain or branched alkyl
group having 1 to 4 carbon atoms.
[0043] Each X is independently from each other an optionally
substituted hydrocarbon group having 1 to 10 carbon atoms, more
preferably having 1 to 4 carbon atoms, which can be interrupted by
at least one heteroatom. "Interrupted by at least one heteroatom"
means that the main chain of a residue comprises, as a chain
member, at least one atom that differs from carbon atom.
Preferably, each X is independently from each other an alkyl group
having 1 to 10 carbon atoms, preferably an alkyl group having 1 to
4 carbon atoms, particularly preferred methyl or ethyl.
[0044] In a preferred embodiment of the present invention, m in
formula (1) has the value 0 or 1, so two or three hydroxyl- or
hydrolysable groups, preferably alkoxy groups, are present.
Generally, polymers that contain di- or trialkoxysilyl groups have
highly reactive linking sites, which make rapid curing, high
degrees of crosslinking and thus good final strengths possible. The
particular advantage of dialkoxysilyl groups is that the
corresponding compositions are, after curing, softer and more
elastic than systems containing trialkoxysilyl groups. They are
therefore particularly suitable for utilization as sealants. In
addition, they release less alcohol upon curing, and thus offer an
application advantage from a physiological standpoint as well. With
trialkoxysilyl groups, on the other hand, a higher degree of
crosslinking can be achieved, which is particularly advantageous if
a hard, solid substance is desired after curing. Trialkoxysilyl
groups are moreover more reactive, i.e. crosslink more quickly, and
thus decrease the quantity of catalyst required, and they have
advantages in terms of "cold flow."
R is a difunctional organic group, which can be a hydrocarbon group
having 1 to 12 carbon atoms, preferably an alkylene group having 1
to 6 carbon atoms, and particularly preferably an alkylene group
having 1 to 3 carbon atoms. More preferably, R is a methylene,
ethylene or n-propylene residue. Methylene and n-propylene residues
are particularly preferably used. In particular, compounds where R
is methylene exhibit high reactivity in the terminating silyl
groups, which contributes to shorter curing and hardening times. If
a propylene group is selected for R, these compounds then exhibit
particularly high flexibility. The curing rate of formulations
based on these polymers can also be influenced by means of the
length of the hydrocarbon residues which form the link between the
polymer backbone and silyl residue.
[0045] The isocyanatosilanes listed below are particularly
suitable: 3-isocyanatopropyltrimethoxysilane,
2-isocyanatoisopropyltrimethoxysilane,
4-isocyanato-n-butyltrimethoxysilane,
2-isocyanato-1,1-dimethylethyltrimethoxysilane,
1-isocyanatomethyltrimethoxysilane,
3-isocyanatopropyltriethoxysilane,
2-isocyanato-2-methylethyltriethoxysilane,
4-isocyanatobutyltriethoxysilane,
2-isocyanato-1,1-dimethylethyltriethoxysilane,
1-isocyanatomethyltriethoxysilane,
3-isocyanatopropylmethyldimethoxysilane,
3-isocyanatopropyldimethylmethoxysilane,
3-isocyanatopropylphenylmethylmethoxysilane,
1-isocyanatomethylmethyldimethoxysilane,
3-isocyanatopropylethyldiethoxysilane,
3-isocyanatopropylmethyldiethoxysilane,
1-isocyanatomethylmethyldiethoxysilane, and mixtures thereof.
[0046] 3-isocyanatopropyltrimethoxysilane,
3-isocyanatopropyltriethoxysilane,
1-isocyanatomethyltriethoxysilane,
3-isocyanatopropylmethyldimethoxysilane,
1-isocyanatomethylmethyldimethoxysilane,
1-isocyanatomethylmethyldiethoxysilane, or mixtures thereof are
more particularly preferred.
[0047] In a specific embodiment, according to the present
invention, aforementioned process for preparing a silylated
polyurethane comprises further step of adding a catalyst. Suitable
catalysts are well known. In principle, any compound that can
catalyze reaction of a hydroxyl group and an isocyanato group to
form a urethane bond can be used. Examples thereof include tin
compounds, like tin carboxylates such as dibutyltin dilaurate
(DBTL), dibutyltin diacetate, dibutyltin diethylhexanoate,
dibutyltin dioctoate, dibutyltin dimethylmaleate, dibutyltin
diethylmaleate, dibutyltin dibutylmaleate, dibutyltin
diiosooctylmaleate, dibutyltin ditridecylmaleate, dibutyltin
dibenzylmaleate, dibutyltin maleate, dibutyltin diacetate, tin
octaoate, dioctyltin distearate, dioctyltin dilaurate (DOTL),
dioctyltin diethylmaleate, dioctyltin diisooctylmaleate, dioctyltin
diacetate, and tin naphthenoate; tin alkoxides such as dibutyltin
dimethoxide, dibutyltin diphenoxide, and dibutyltin diisoproxide;
tin oxides such as dibutyltin oxide and dioctyltin oxide; reaction
products between dibutyltin oxides and phthalic acid esters,
dibutyltin bisacetylacetonate; as well as non-tin compounds. The
latter include titanates such as tetrabutyl titanate and
tetrapropyl titanate; organoaluminum compounds such as aluminum
trisacetylacetonate, aluminum trisethylacetoacetate, and
diisopropoxyaluminum ethylacetoacetate; chelate compounds such as
zirconium tetraacetylacetonate and titanium tetraacetylacetonate;
lead octanoate; amine compounds or salts thereof with carboxylic
acids, such as butylamine, octylamine, laurylamine, dibutylamines,
monoethanolamines, diethanolamines, triethanolamine,
diethylenetriamine, triethylenetetramine, oleylamines,
cyclohexylamine, benzylamine, diethylaminopropylamine,
xylylenediamine, triethylenediamine, guanidine, diphenylguanidine,
2,4,6-tris(dimethylaminomethyl)phenol, morpholine,
N-methylmorpholine, 2-ethyl-4-methylimidazole, and
1,8-diazabicyclo-(5,4,0)-undecene-7 (DBU), a low-molecular-weight
polyamide resin obtained from an excess of a polyamine and a
polybasic acid, adducts of a polyamine in excess with an epoxy,
silane adhesion promoters having amino groups, such as
3-aminopropyltrimethoxysilane and
aminoethyl)aminopropylmethyldimethoxysilane, as well as compounds
of potassium, iron, indium, zinc, bismuth, and copper, preferably
carboxylates (salts of aliphatic carboxylic acids) or
acetylacetonates of potassium, iron, indium, zinc, bismuth, or
copper. Preferably, the catalyst is selected from the group
consisting of compounds of potassium, iron, indium, zinc, bismuth,
and copper, preferably carboxylates (salts of aliphatic carboxylic
acids) or acetylacetonates of potassium, iron, indium, zinc,
bismuth, or copper. C.sub.4 to C.sub.36 saturated, mono- or
polyunsaturated monocarboxylic acids cab be used, in particular as
aliphatic carboxylic acids. Examples thereof are: arachidic acid
(n-eicosanoic acid), arachidonic acid
(all-cis-5,8,11,14-eicosatetraenoic acid), behenic acid (docosanoic
acid), butyric acid (butanoic acid), caproleic acid (9-decenoic
acid), capric acid (n-decanoic acid), caproic acid (n-hexanoic
acid), caprylic acid (n-octanoic acid), cerotic acid (hexacosanoic
acid), cetoleic acid (cis-11-docosenoic acid), clupanodonic acid
(all-cis-7,10,13,16,19-docosapentaenoic acid), eleostearic acid
(trans-9-trans-11-cis-13-octadeca-9,11,13-trienoic acid), enanthic
acid (1-hexanecarboxylic acid), erucic acid (cis-13-docosenoic
acid), gadoleic acid (9-eicosenoic acid), gondoic acid
(cis-11-eicosenoic acid), hiragonic acid (6,10,14-hexadecatrienoic
acid), lauric acid (dodecanoic acid), lignoceric acid
(tetracosanoic acid), linderic acid (cis-4-dodecenoic acid),
linoleic acid ((cis,cis)-octadeca-9,12-dienoic acid), linolenic
acid ((all-cis)-octadeca-9,12,15-trienoic acid), melissic acid
(triacontanoic acid), montanic acid (octacosanoic acid),
stearidonic acid (cis-6-cis-9-cis-12-cis-15-octadecatetraenoic
acid), myristic acid (tetradecanoic acid), myristoleic acid
(cis-9-tetradecenoic acid), naphthenic acid, neodecanoic acid,
obtusilic acid (cis-4-decenoic acid), caprylic acid (n-octanoic
acid), neooctanoic acid, oleic acid (cis-9-octadecenoic acid),
palmitic acid (n-hexadecanoic acid), palmitoleic acid
(cis-9-hexadecenoic acid), parinaric acid
(9,11,13,15-octadecatetraenoic acid), petroselinic acid
(cis-6-octadecenoic acid), physeteric acid (5-tetradecenoic acid),
punicic acid (cis-9-trans-11-cis-13-octadeca-9,11,13-trienoic
acid), scoliodonic acid (cis-5-cis-11-cis-14-eicosatrienoic acid),
selacholeic acid (15-tetracosenoic acid), stearic acid
(n-octadecanoic acid), tricosanoic acid, tsuzuic acid
(cis-4-tetradecenoic acid), trans-vaccenic acid
(trans-11-octadecenoic acid), palmitoleic acid (9-hexadecenoic
acid). In addition to the acetylacetonates, chelates of other
.beta.-dicarbonyl compounds of potassium, iron, indium, zinc,
bismuth, or copper can also be used. Acetoacetic acid alkyl esters,
dialkyl malonates, benzoylacetic esters, dibenzoylmethane,
benzoylacetone, and dehydroacetoacetic acid may be recited
concretely.
[0048] The present invention also provides a process for preparing
a silylated polyurethane comprising the following steps: [0049] (a)
reacting at least one polyol with at least one triisocyanate to
form a hydroxyl-terminated polyurethane prepolymer; and [0050] (b)
reacting said polyurethane prepolymer with at least one
isocyanatosilane of the formula (1)
[0050] OCN--R--Si--(X).sub.m(R.sup.1).sub.3-m (1) [0051] wherein
[0052] m is 0, 1 or 2, [0053] each R.sup.1 is independently from
each other a hydroxyl group, an alkoxy group having 1 to 10 carbon
atoms, an acyloxy group having 1 to 10 carbon atoms, or
--OCH(R.sup.2)COOR.sup.3, wherein R.sup.2 is hydrogen or an alkyl
group having 1 to 4 carbon atoms and R.sup.3 is a straight-chain or
branched alkyl group having 1 to 8 carbon atoms, [0054] each X is
independently from each other an optionally substituted hydrocarbon
group having 1 to 10 carbon atoms, which can be interrupted by at
least one heteroatom, and [0055] R is a difunctional organic group,
[0056] to endcap the hydroxyl groups on said prepolymer with said
isocyanatosilane.
[0057] The general, preferred, and particularly preferred
embodiments described for the silylated polyurethane according to
the present invention thus also apply to the process for preparing
the silylated polyurethane according to the present invention.
[0058] The present invention also provides a curable composition,
in particular an adhesive, sealant, or coating composition
comprising at least one silylated polyurethane according to the
invention or obtainable by the aforementioned process according to
the present invention.
[0059] The adhesive, sealant, coating composition according to the
present invention can also contain, in addition to the
aforementioned silylated polyurethane according to the present
invention, further adjuvants and additives that impart to these
adhesive, sealant, coating composition improved elastic properties,
improved elastic recovery, a sufficiently long processing time, a
fast curing time, and low residual tack. Included among these
adjuvants and additives are, for example, catalysts, plasticizers,
stabilizers, antioxidants, fillers, reactive diluents, drying
agents, adhesion promoters and UV stabilizers, fungicides, flame
retardants, rheological adjuvants, color pigments or color pastes,
and/or optionally also, to a small extent, solvents.
[0060] A "plasticizer" is understood as a substance that decreases
the viscosity of the compositions and thus facilitates
processability. The plasticizer is preferably selected from a fatty
acid ester, a dicarboxylic acid ester, an ester of
OH-group-carrying or epoxidized fatty acids, a fat, a glycolic acid
ester, a benzoic acid ester, a phosphoric acid ester, a sulfonic
acid ester, a trimellitic acid ester, an epoxidized plasticizer, a
polyether plasticizer, a polystyrene, a hydrocarbon plasticizer,
and a chlorinated paraffin, as well as mixtures of two or more
thereof. Targeted selection of one of these plasticizers, or of a
specific combination, can result not only in a decrease in
viscosity and thus better processability, but also in further
advantageous properties of the composition according to the present
invention, e.g. the gelling capability of the polymers,
low-temperature elasticity and/or low-temperature strength, or even
antistatic properties.
[0061] In principle, phthalic acid esters can be used as a
plasticizer. However, these are not preferred due to their
toxicological potential.
[0062] Of the polyether plasticizers, it is preferred to use
end-capped polyethylene glycols, for example polyethylene or
polypropylene glycol di-C.sub.1-4 alkyl ethers, in particular
dimethyl or diethyl ethers of diethylene glycol or dipropylene
glycol, as well as mixtures of two or more thereof. Also suitable
as plasticizers are, for example, esters of abietic acid, butyric
acid esters, acetic acid esters, propionic acid esters, thiobutyric
acid esters, citric acid esters, and esters based on nitrocellulose
and polyvinyl acetate, as well as mixtures of two or more thereof.
Also suitable are, for example, the asymmetrical esters of adipic
acid monooctyl ester with 2-ethylhexanol (Edenol DOA, Cognis
Deutschland GmbH, Dusseldorf). The pure or mixed ethers of
monofunctional, linear or branched C.sub.4-16 alcohols, or mixtures
of two or more different ethers of such alcohols, for example
dioctyl ethers (obtainable as Cetiol OE, Cognis Deutschland GmbH,
Dusseldorf), are also suitable as plasticizers. Likewise, suitable
in the context of the present invention as plasticizers are
diurethanes, which can be manufactured e.g. by reacting diols
having OH terminal groups with monofunctional isocyanates, by
selecting the stoichiometry so that substantially all the free OH
groups react completely. A further method for manufacturing
diurethanes involves reacting monofunctional alcohols with
diisocyanates, such that all the NCO groups react as completely as
possible.
[0063] Plasticizers can be additionally used in the composition at
between 0 and 40, by preference between 0 and 20 wt %, based on the
total weight of the composition.
[0064] "Stabilizers" for purposes of this invention are to be
understood as antioxidants, UV stabilizers, or hydrolysis
stabilizers. Examples thereof are the commercially usual sterically
hindered phenols and/or thioethers and/or substituted
benzotriazoles and/or amines of the hindered amine light stabilizer
(HALS) type. It is preferred in the context of the present
invention if a UV stabilizer that carries a silyl group, and that
is incorporated into the end product upon crosslinking or curing,
is used. The products Lowilite 75, Lowilite 77 (Great Lakes, USA)
are particularly suitable for this purpose. Benzotriazoles,
benzophenones, benzoates, cyanoacrylates, acrylates, sterically
hindered phenols, phosphorus, and/or sulfur can also be added.
[0065] The composition according to the present invention can
contain up to approximately 2 wt %, by preference approximately 1
wt % stabilizers. In addition, the composition according to the
present invention can further contain up to approximately 7 wt %,
in particular up to approximately 5 wt % antioxidants.
[0066] The catalysts that can be used are all known compounds that
can catalyze hydrolytic cleavage of the hydrolyzable groups of the
silane groupings, as well as subsequent condensation of the Si--OH
group to yield siloxane groupings (crosslinking reaction and
adhesion promotion function). Examples thereof are titanates such
as tetrabutyl titanate and tetrapropyl titanate, tin carboxylates
such as dibutyltin dilaurate (DBTL), dibutyltin diacetate,
dibutyltin diethylhexanoate, dibutyltin dioctoate, dibutyltin
dimethylmaleate, dibutyltin diethylmaleate, dibutyltin
dibutylmaleate, dibutyltin diiosooctylmaleate, dibutyltin
ditridecylmaleate, dibutyltin dibenzylmaleate, dibutyltin maleate,
dibutyltin diacetate, tin octaoate, dioctyltin distearate,
dioctyltin dilaurate (DOTL), dioctyltin diethylmaleate, dioctyltin
diisooctylmaleate, dioctyltin diacetate, and tin naphthenoate; tin
alkoxides such as dibutyltin dimethoxide, dibutyltin diphenoxide,
and dibutyltin diisoproxide; tin oxides such as dibutyltin oxide
and dioctyltin oxide; reaction products between dibutyltin oxides
and phthalic acid esters, dibutyltin bisacetylacetonate;
organoaluminum compounds such as aluminum trisacetylacetonate,
aluminum trisethylacetoacetate, and diisopropoxyaluminum
ethylacetoacetate; chelate compounds such as zirconium
tetraacetylacetonate and titanium tetraacetylacetonate; lead
octanoate; amine compounds or salts thereof with carboxylic acids,
such as butylamine, octylamine, laurylamine, dibutylamines,
monoethanolamines, diethanolamines, triethanolamine,
diethylenetriamine, triethylenetetramine, oleylamines,
cyclohexylamine, benzylamine, diethylaminopropylamine,
xylylenediamine, triethylenediamine, guanidine, diphenylguanidine,
2,4,6-tris(dimethylaminomethyl)phenol, morpholine,
N-methylmorpholine, 2-ethyl-4-methylimidazole, und
1,8-diazabicyclo-(5,4,0)-undecene-7 (DBU), a low-molecular-weight
polyamide resin obtained from an excess of a polyamine and a
polybasic acid, adducts of a polyamine in excess with an epoxy,
silane adhesion promoters having amino groups, such as
3-aminopropyltrimethoxysilane and
N-(.beta.-aminoethyl)aminopropylmethyldimethoxysilane.
[0067] The catalyst, preferably mixtures of several catalysts, can
be used in a quantity from 0.01 to approximately 5 wt % based on
the entire weight of the composition.
[0068] The composition according to the present invention can
additionally contain fillers. Suitable here are, for example,
chalk, lime powder, precipitated and/or pyrogenic silicic acid,
zeolites, bentonites, magnesium carbonate, diatomite, alumina,
clay, talc, titanium oxide, iron oxide, zinc oxide, sand, quartz,
flint, mica, glass powder, and other ground mineral substances.
Organic fillers can also be used, in particular carbon black,
graphite, wood fibers, wood flour, sawdust, cellulose, cotton,
pulp, cotton, wood chips, chopped straw, chaff, ground walnut
shells, and other chopped fibers. Short fibers such as glass
fibers, glass filament, polyacrylonitrile, carbon fibers, Kevlar
fibers, or polyethylene fibers can also be added. Aluminum powder
is likewise suitable as a filler.
[0069] The pyrogenic and/or precipitated silicic acids
advantageously have a BET surface area from 10 to 90 m.sup.2/g.
When they are used, they do not cause any additional increase in
the viscosity of the composition according to the present
invention, but do contribute to strengthening the cured
composition.
[0070] It is likewise conceivable to use pyrogenic and/or
precipitated silicic acids having a higher BET surface area,
advantageously 100 to 250 m.sup.2/g, in particular 110 to 170
m.sup.2/g, as a filler. Because of the greater BET surface area,
the same effect, e.g. strengthening the cured composition, is
achieved with a smaller weight proportion of silicic acid. Further
substances can thus be used to improve the composition according to
the present invention in terms of different requirements.
[0071] Also suitable as fillers are hollow spheres having a mineral
shell or a plastic shell. These can be, for example, hollow glass
spheres that are obtainable commercially under the trade names
Glass Bubbles.RTM.. Plastic-based hollow spheres, e.g.
Expancel.RTM. or Dualite.RTM., are described e.g. in EP 0 520 426
B1. They are made up of inorganic or organic substances and each
have a diameter of 1 mm or less, preferably 500 .mu.m or less.
[0072] Fillers that impart thixotropy to the composition are
preferred for many applications. Such fillers are also described as
rheological adjuvants, e.g. hydrogenated castor oil, fatty acid
amides, or swellable plastics such as PVC. In order to be readily
squeezable out of a suitable dispensing apparatus (e.g. a tube),
such compositions possess a viscosity from 3000 to 150,000,
preferably 40,000 to 80,000 mPas, or even 50,000 to 60,000
mPas.
[0073] The fillers can be used by preference in a quantity from 1
to 80 wt %, by preference from 5 to 60 wt %, based on the total
weight of the composition.
[0074] Examples of suitable pigments are titanium dioxide, iron
oxides, or carbon black.
[0075] In order to enhance shelf life even further, it is often
advisable to further stabilize the composition according to the
present invention with respect to moisture penetration using drying
agents. A need occasionally also exists to lower the viscosity of
the adhesive or sealant according to the present invention for
specific applications, by using a reactive diluent. All compounds
that are miscible with the adhesive or sealant with a reduction in
viscosity, and that possess at least one group that is reactive
with the binder, can be used as reactive diluents.
[0076] The following substances can be used, for example, as
reactive diluents: polyalkylene glycols reacted with
isocyanatosilanes (e.g. Synalox 100-50B, Dow),
carbamatopropyltrimethoxysilane, alkyltrimethoxysilane,
alkyltriethoxysilane, methyltrimethoxysilane,
methyltriethoxysilane, and vinyltrimethoxysilane (VTMO Geniosil XL
10, Wacker), vinyltriethoxysilane, phenyltrimethoxysilane,
phenyltriethoxysilane, octyltrimethoxysilane, tetraethoxysilane,
vinyldimethoxymethylsilane (XL12, Wacker), vinyltriethoxysilane
(GF56, Wacker), vinyltriacetoxysilane (GF62, Wacker),
isooctyltrimethoxysilane (10 Trimethoxy), isooctyltriethoxysilane
(10 Triethoxy, Wacker), N-trimethoxysilylmethyl-O-methyl carbamate
(XL63, Wacker), N-dimethoxy(methyl)silylmethyl-O-methyl carbamate
(XL65, Wacker), hexadecyltrimethoxysilane,
3-octanoylthio-1-propyltriethoxysilane, and partial hydrolysates of
the aforementioned compounds.
[0077] Also, usable as reactive diluents are the following polymers
of Kaneka Corp.: MS S203H, MS S303H, MS SAT 010, and MS SAX
350.
[0078] Silane-modified polymers that are derived, for example, from
the reaction of isocyanatosilane with Synalox grades can likewise
be used.
[0079] In the same manner, the silylated polyurethanes according to
the present invention can be used in a mixture with usual polymers
or prepolymers known per se, optionally with concurrent use of the
aforementioned reactive diluents, fillers, and further adjuvants
and additives. "Usual polymers or prepolymers" can be selected in
this context from polyesters, polyoxyalkylenes, polyacrylates,
polymethacrylates, or mixtures thereof; these can be free of groups
reactive with siloxane groups, but optionally can also comprise
alkoxysilyl groups or hydroxyl groups.
[0080] A plurality of the aforementioned silane-functional reactive
diluents have at the same time a drying and/or adhesion-promoting
effect in the composition. These reactive diluents may be used in
quantities between 0.1 and 15 wt %, by preference between 1 and 5
wt %, based on the total weight of the composition.
[0081] Also suitable as adhesion promoters, however, are so-called
tackifying agents, such as hydrocarbon resins, phenol resins,
terpene-phenolic resins, resorcinol resins or derivatives thereof,
modified or unmodified resin acids or resin esters (abietic acid
derivatives), polyamines, polyaminoamides, anhydrides, and
anhydride-containing copolymers. The addition of polyepoxide resins
in small quantities can also improve adhesion on many substrates.
The solid epoxy resins having a molecular weight of over 700, in
finely ground form, are then preferably used for this. If
tackifying agents are used as adhesion promoters, their nature and
quantity depend on the adhesive/sealant composition and on the
substrate onto which it is applied. Typical tackifying resins
(tackifiers) such as, for example, terpene-phenolic resins or resin
acid derivatives, may be used in concentrations between 5 and 20 wt
%; typical adhesion promoters such as polyamines, polyaminoamides,
or phenolic resins or resorcinol derivatives may be used in the
range between 0.1 and 10 wt %, based on the total weight of the
composition.
[0082] The present invention also provides the use of the silylated
polyurethane according to the present invention as an adhesive,
sealant, coating composition, or for the production thereof.
[0083] In principle in the present invention, all features listed
within the context of the present text, particularly the
embodiments, proportional ranges, components and other features of
the composition according to the invention, of the method according
to the invention and of the use according to the invention
identified as preferred and/or special, can be implemented in all
possible and not mutually exclusive combinations, with combinations
of features identified as preferred and/or special also being
regarded as preferred and/or special.
EXAMPLES
Example 1 (Ex 1)
[0084] Manufacture of a Silylated Polyurethane (Use of
Triisocyanate):
[0085] 384.02 g (33.88 mmol) of polypropylene ether polyol (Acclaim
12200, hydroxyl value=9.90) were dried in a 500 ml three-necked
flask at 80-90.degree. C. under vacuum. Under a nitrogen
atmosphere, 0.28 g of bismuth neodecanoate (Borchi Kat 315) were
added with stirring. Then, 2.52 g (4.52 mmol) of triisocyanate
(Tolonate HDT-LV) were added (NCO/OH ratio=0.2) with stirring. The
mixture was left for one hour at 80-95.degree. C. The conversion
was accomplished with NCO monitoring, and as soon as the
theoretical NCO value of the prepolymer had been reached
titrimetrically (% NCO=0), 13.18 g (62.69 mmol) of
3-isocyanatopropyltrimethoxysilane (Geniosil GF 40) were added with
stirring and the mixture was left for a further hour at
80-95.degree. C. (% NCO=0.00 to 0.09). A star-shaped polymer was
obtained. The resulting polymer was stored in a moisture-proof
glass vessel under a nitrogen atmosphere before being processed
further into a curable composition. The viscosity was 41,200
mPas.
Comparative Example 1 (Comp 1)
[0086] Manufacture of a Silylated Polyurethane (Use of
Diisocyanate):
[0087] A similar procedure to Example 1 was carried out except that
HDI was used instead of triisocyanate. The viscosity was 28,200
mPas. Details are summarized in Table 1.
Example 2 (Ex 2)
[0088] Manufacture of a Silylated Polyurethane (Use of
Triisocyanate):
[0089] A similar procedure to Example 1 was carried out except that
NCO/OH ratio=0.4 and Acclaim 4200 (hydroxyl value=29.50) was used
instead of Acclaim 12200.
[0090] The viscosity was 78,600 mPas. Details are summarized in
Table 1.
Comparative Example 2 (Comp 2)
[0091] Manufacture of a Silylated Polyurethane (Use of
Diisocyanate):
[0092] A similar procedure to Example 2 was carried out except that
HDI was used instead of triisocyanate. The viscosity was 10,600
mPas. Details are summarized in Table 1.
TABLE-US-00001 TABLE 1 Ex 1 Comp 1 Ex 2 Comp 2 Acclaim 384.02 g
385.33 g 12200 (33.88 mmol) (34.00 mmol) Acclaim 4200 357.13 g
364.02 g (93.90 mmol) (95.71 mmol) Borchi Kat 0.28 g 0.28 g 0.28 g
0.28 g 315 Tolonate 2.52 g 13.95 g HDT-LV (4.52 mmol) (25.04 mmol)
HDI 1.16 g 6.52 g (6.80 mmol) (38.28 mmol) NCO/OH ratio 0.2 0.2 0.4
0.4 Geniosil GF 13.18 g 13.23 g 28.64 g 29.18 g 40 (62.69 mmol)
(62.90 mmol) (136.15 mmol) (138.78 mmol) % NCO 0.00-0.09 0.00-0.09
0.00-0.25 0.00-0.25 after adding Geniosil GF 40 Viscosity 41,200
mPas 28,200 mPas 78,600 mPas 10,600 mPas
Determination of the Viscosity of the Polymer:
[0093] The viscosity values were determined using Brookfield
viscometer (DV-II+Pro), spindle 7, 20 rpm, at 23.degree. C.
Examples A-F
[0094] Manufacture of Compositions Comprising a Silylated
Polyurethane:
[0095] Each prepared silylated polyurethane according to above
examples was heated for 24 hours at 23.degree. C. and then 0.35 g
of N-(2-Aminoethyl)-3-aminopropyltrimethoxysilane (Geniosil GF 91)
and 0.14 g of DOTL or DBU were added to 34.51 g of each of the
prepared polymer. This mixture was homogenized twice for 60 seconds
at 2700 rpm in a SpeedMixer (DAC 150 FC).
[0096] The time to form a skin (skin over time/SOT) and mechanical
strength (tensil strength and elongation) were determined for the
abovementioned mixtures. The results are summarized in Table 2
below. DOTL was used in preparing Examples A to D and DBU was used
as a tin-free catalyst in preparing Examples E to F.
TABLE-US-00002 TABLE 2 A B C D E F Silylated Ex 1 Comp 1 Ex 2 Comp
2 Ex 1 Comp 1 Polyurethane SOT 14 min 16 min 22 min 1 h 21 min 33
min 44 min Tensil 0.88 0.85 1.10 0.89 0.80 0.76 Strength
(N/mm.sup.2) Elongation 57.98 61.75 43.28 39.38 55.53 53.88 (%)
Determination of the Skin-Over Time (SOT) and Mechanical Strength
(Tensil Strength and Elongation):
[0097] The aforementioned mixtures were homogenized and applied in
a frame (50.times.130.times.2 mm). Each mixture was evenly
distributed so that the frame can be completely filled. A thin
polymer film was thereby obtained. The time to form a skin
(skin-over time/SOT) was determined for these compositions using a
tool which has a rounded spatula at the tip (150.times.5 mm). The
tip of the spatula was gently contacted with the surface of the
polymer film every 1 to 5 minutes and removed carefully. The SOT
was measured once no more residue of the formulation remains on the
spatula when removing it from the surface of the polymer film.
Then, the resulting string must be removed from the spatula without
residue. The polymer film returned to its original shape. In
examining the SOT a different part of the surface of the polymer
film must be used every time. The test was performed at 23.degree.
C. and 50% relative humidity.
[0098] After being stored for 7 days (23.degree. C., 50% relative
humidity), four specimens were prepared from the polymer film and
punched using a Mader press (APK T3-5-40) and a punching tool unit
according to DIN 53504-S3A. The mechanical data were determined by
reference to DIN 53504:2009-10. Each specimen was set to the
initial test position using a pre-load of 0.05 MPa and a speed rate
of 40 mm/min. Actual measurement was done using a speed rate of 50
mm/min.
[0099] The examples show that the mixtures A, C, and E containing a
silylated polyurethane according the present invention (Examples 1
to 2), show reasonable viscosity, exhibit significantly shorter SOT
than mixtures comprising a silylated polyurethane according to the
Comparative Examples 1 to 2, while having good mechanical strength
(tensil strength and elongation). In addition, comparison of
Examples E and F shows that even in case of using non-tin catalyst
the mixture containing a silylated polyurethane according the
present invention also exhibits short SOT and good mechanical
properties.
* * * * *