Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
.. - ~~9~~5~
METHOD OF MAHING LOW UNSATURATION POLYETHER POLYOLS
FIELD OF THE INVENTION
The present invention pertains to polyoxyalkylene polyether polyols, polyol
compositions made
with such polyols; to sealants, adhesives, and elastomers made with these
polyoxyalkylene polyols and
to the methods for preparing each product. More particularly, the sealants,
adhesives, and elastomers
are made with a polyoxyalkylene polyether polyol having an internal block of
polyoxypropylene
1 o attached to the nucleus of an initiator molecule, followed by at least a
C4 or higher alkylene oxide in an
amount sufficient to reduce the degree of unsaturation of the polyol to 0.06
meq/g of polyol or less.
BACKGROUND OF THE INVENTION
Methods of preparing elastomers are well known in the art. In general, an
elastomer is
prepared by reacting a polyoxyalkylene polyether pvlyol with an organic
isocyanate in the presence of a
chain extender. The chain extender may be a diol or a mixture of triols and
diols such that the overall
functionality of the mixture is generally less than 2.3. The polyoxyalkylene
polyether polyols used in
the preparation of elastomers generally have molecular weights ranging from
2,000 to 5,000. For the
preparation of sealants, the chain extender may be a triol or a mixture of
diols, triols, and/or tetrols,
such that the overall functionality of the mixture ranges from greater than
2.3 to 3Ø
2 o Polyoxyalkylene polyether polyols used in the preparation of polyurethane
elastomers are
generally prepared by reacting an initiator compound with an alkylene oxide in
the presence of a basic
catalyst such as sodium hydroxide, potassium hydroxide, tertiary amine, or an
alkoxide. Such catalysts
are useful in the preparation of polyoxypropylene polyols until the equivalent
weight of the polyol
i-edches about 1,000 to 1,200, at which point an excess of allylic terminal
unsaturation starts to
1
~~.9~~5~
develop. Formation of unsaturation is believed to be a consequence of
propylene oxide isomerizing to
ally) alcohol, which subsequently reacts with propylene oxide to form allyl (2-
propenyl)ethers of
polyoxypropylene. The point at which unsaturation begins to develop and the
rate of unsaturation can
be influenced by variables such as, temperature, pressure, catalyst
concentration, and the type of
catalyst employed. Beyond certain equivalent weights, it becomes difficult, if
not impossible, to make a
polyoxypropylene polyether polyol having adequate functionality using
conventional catalysts. Thus,
as is discussed further below, many attempts have been made to solve the
problem of unsaturation by
varying the kinds of catalysts used in the preparation of the polyol.
The drawback of polyether polyols having high levels of unsaturation is that
the allylic tenrunal
1 o unsaturation reduces the functionality of the polyol and terminates chain
growth in the final
polyurethane, thereby reducing the polyol's equivalent weight and broadening
its molecular weight
distribution. Employing a polyether polyol with a less than anticipated
functionality and a high level of
unsaturation in the manufacture of polyurethane sealants and elastomers
results in the degradation of
mechanical properties, such as hardness and tensile strength. While one may
keep the level of
unsaturation low by making a very low equivalent weight polyol, elastomers and
sealants should be
made with high equivalent weight polyols to enhance their elasticity.
Therefore, it is highly desirable to
manufacture a high equivalent weight polyether polyol, suitable in the
manufacture of sealants,
adhesives, and elastomers, which approximates the functionality of the
initiator as close as possible.
Several attempts have been made to reduce the unsaturation of polyoxyalkylene
polyether
2 o polyols by experimenting with the kinds of catalysts used in their
preparation. For example, U.S.
Patents 5,136,010; 5,185,420; 5,266,681; 5,116,93 I; 5,096,993; 4,985,491 each
dfsclose the
preparation of polyether polyols using a double metal cyanide (DMC) catalyst
to reduce the level of
f
unsaturation down to about 0.04 meq/g of polyol or less. The disadvantages of
using DMC catalysts
2
219352.
to prepare polyols are that such catalysts are quite expensive; and, as
reported in U.S. Patent
4,355,188, the polyols containing the DMC catalyst residues are less stable
during storage, may give an
odor to the polyol, and causes undesirable side reactions during the
manufacture of polyurethane
products. In the manufacture of a block polyether polyol having an oxyethylene
cap, it is usually
necessary to remove the DMC catalyst used to prepare the block of oxypropylene
goups prior to
polymerizing the cap of ethylene oxide, because the DMC residual catalyst
would prevent the uniform
addition of ethylene oxide across all functional sites on the growing polymer.
Thus, DMC must be
removed and a standard catalyst, such as KOH, must be added as additional
processing steps when
polymerizing blocks of oxyethylene groups.
to U.S. Patents 4,902,834 and 4,764,567 describe the use of an alternative
catalyst, cesium
hydroxide, for reducing the unsaturation of polyoxyethylene polyether polyols.
These patents,
however, lack general teachings on how and what catalysts would be effective
to reduce the
unsaturation of polyoxypropylene polyether polyols. Furthermore, it would be
desirable to
manufacture a polyether polyol with its level of unsaturation not so dependent
upon a specific catalyst.
In addition to double metal cyanide and cesium based catalysts for lowering
the unsaturation of
polyether polyols, U. S. Patents 5,010,187 and 5,070,125 also describe the use
of barium or strontium
based catalysts for reducing unsaturation. As with the cesium and DMC
catalysts described above, it
would be desirable to manufacture a low unsaturation polyether polyol which is
not catalyst-dependent.
U.S. Patent 4,687,851 discloses a polyether polyol having an unsaturation
level of 0.06 meq/g
or less made with conventional tertiary amines or sodium and potassium
hydroxides. To obtain the low
unsaturation, the polyether polyol must be amine-initiated. There continues to
exist a need for the
' manufacture of polyether polyols having a low degee of unsaturation which
are not limited to a
3
' ~ 2~.9~25~
specific initiator and which can be manufactured in the presence of
conventional or other low cost
catalysts.
In this regard, we began to investigate lowering the degree of unsaturation
through methods
other than improving processing techniques or divising new catalysts. We went
down a path not
thought of as a means for lowering unsaturation. By altering the structure of
the polyol molecule, we
discovered that the degree of unsaturation can be lowered significantly no
matter what kind of catalyst
is employed.
The structure of polyether polyols can vary widely depending upon the desired
application.
For example, conjugated or block polymers of ethylene oxide and propylene
oxide reacted onto an
to initiator molecule are known to impart unique properties in a particular
application depending upon the
order of oxide addition. U. S. Patents 3,036,118 and 3,036,130 each disclose
conjugated block
polymers of polyether polyols having an internal oxyethylene block followed by
a block of
oxypropylene groups for use as nonionic surface active agents. U.S. Patent No.
4,738,993 also
discloses a polyether polyol having an internal block of oxyethylene groups
useful in the manufacture of
RIM polyurethane elastomers. Polyether polyols having an internal block of
oxyethylene groups have
also found use in improving the air flow and load bearing properties of
polyurethane foams, as
disclosed in U.S. Patent No. 4,487,854.
Reversing the order of ethylene oxide and propylene oxide addition is also
known. For
example, surface active, detergent, and anti-foam polyether polyols having an
internal block of
2 0 oxypropylene groups followed by a chain of oxyethylene groups are known
according to the teachings
of U.S. Patents 2,674,619 and 2,948,757. Such polyols have also found use in
the manufacture of
flexible polyurethane foams according to U.S. Patent No. 3,865,762.
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4
219322
Polyether polyols having a heteric structure, wherein a mixture of alkylene
oxides are added
onto the initiator molecule such that the oxyalkylene groups are distributed
in a random fashion on
each molecule, are also known according to the teachings of various patents.
According to these
patents, suitable alkylene oxides usually include ethylene oxide, propylene
oxide, and butylene oxide.
For example, U.S. Patent No. 4,812,350 teaches the manufacture of a heteric
polyether polyol having
certain weight proportions of ethylene oxide and either butylene oxide and/or
propylene oxide for use
as an adhesion enhancer in covered polyurethane foam panels. U.S. Patent No.
2;733,272
recommends using a heteric polyoxyethylene-polyoxypropylene polyether of
glycerol as a lubricant,
especially in brake fluids. Heteric polyether diols are also disclosed in U.S.
Patent No. 2,425,845, and
l0 U.S. Patent No. 4,301,110 teaches the manufacture of a polyether polyol
having a heteric structure of
oxyethylene and oxybutylene groups, optionally capped with a block of
oxyethylene groups, useful in
the manufacture of reaction injection molded parts.
There also exist polyether polyols having both a heteric and a blocked
structure. For example,
U.S. Patent No. 4,487,854 discloses a polyether polyol having an internal
block of oxyethylene groups
followed by a heteric mixture of ethylene oxide, butylene oxide, and/or
propylene oxide, optionally
followed b a block of o ro tene or o bu lene ou s as a terminal ca . The of
ether of of is
Y ~ pY xY h' ~' p p P ,Y p Y
said to impart good alr flow properties and load bearing properties to a
polyurethane foam.
None of these patents, however, teach the concept of reducing allylic
unsaturation by altering
the structure of the polyether polymer, or how such alteration should be made
to effect the lowing of
2 0 the degree of unsaturation. Further, most of these polyether polyols are
too hydrophilic to be useful in
elastomer sealant and adhesive applications.
SUMMARY OF THE INVENTION
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5
CA 02193252 2003-12-10
It would be desirable to have a high equivalent
weight polyether polyol containing a block of oxypropylene
groups with reduced unsaturation. It would also be highly
desirable that such polyether polyol can be prepared using
an economical catalyst and whose method of preparation is
not dependent upon employing a particular catalyst in order
to achieve a reduction in unsaturation. We also sought to
make a reduced unsaturation polyether polyol whose degree
of unsaturation is not dependent upon the kind of initiator
used, and specifically, making a reduced unsaturation
polyether polyol which can be initiated with hydroxyl
functional initiators. Further, these polyether polyols
should be suitable for the manufacture of polyurethane
elastomers, sealants, and adhesives, meaning that a
significant portion of the polyether polyols should be
hydrophobic.
There is now provided an isocyanate reactive
polyoxyalkylene polyether polymer having a structure as
follows:
The nucleus of an initiator compound, an internal
block of oxypropylene groups, and a second block of
oxyalkylene groups: the internal block of oxypropylene
groups being disposed between the nucleus of the initiator
and the second block, the second block containing at least
some oxyalkylene groups derived from at least a Cq or
higher alkylene oxide.
More specifically, the present invention is
related to a method of making an isocyanate reactive
polyoxyalkylene polyether polymer having a degree of
unsaturation of 0.06 meq KOH/g of polyol or less comprising
reacting, in the presence of a catalyst, an initiator
6
CA 02193252 2003-12-10
having at least two sites reactive with alkylene oxides
directly or indirectly with, in sequential order, propylene
oxide to form an internal block of oxypropylene groups,
followed by reacting directly or indirectly onto said
internal block of oxypropylene groups one or more kinds of
second oxides) comprising a C4 or higher alkylene oxide to
form a second block of oxyalkylene groups.
This structure allows one to make a polyether
polymer having a low degree of unsaturation, adjust the
degree of hydrophobicity to a wide range of values, and may
be simply manufactured without depending upon the use of
exotic catalysts.
The amount of the internal block of oxypropylene
groups is advantageously from 25 weight percent to 80
weight percent based on the weight of all oxyalkylene
groups and initiator. The amount of the second block
containing a C4 or higher alkylene oxide should be
effective to reduce the unsaturation of the polyether
polyol to 0.06 meq KOH/g of polyol or less.
6a
~1~3~52
The preferable C4 or higher alkylene oxide is 1,2-butylene oxide.
In another embodiment, there is provided a method of making the
polyoxyalkylene polyether
polyol by reacting in the presence of a catalyst an initiator compound having
at least two sites reactive
with an alkylene oxide, directly or indirectly in sequential order, propylene
oxide to form an internal
block of oxypropylene groups, followed by reacting directly or indirectly onto
said block of
oxypropylene goups one or more second oxide compounds, at least one of which
is a C4 or higher
alkylene oxide, to form a second block of oxyalkylene goups.
Likewise, the amount of propylene oxide added is advantageously from 25 weight
percent to
80 weight percent, based on the weight of all oxyalkylene compounds added to
the initiator and the
initiator, and the amount of the one or more second oxide compounds, at least
one of which is a C4 or
higher alkylene oxide, should be effective to reduce the unsaturation of the
polyether polyol to 0.06
meq KOH/g of polyol or less.
In a further embodiment of the invention, there is provided a polyether polyol
and a method of
making such polyether polyol where the propylene oxide is added directly onto
the initiator compound
to form a reaction product having at least an equivalent weight of 800, after
which the one or more
types of second oxides, at least one of which is a Ca or higher alkylene
oxide, are ,added onto the
resulting internal block of oxypropylene groups. This second block of
oxyalkylene groups may
comprise a random mixture of the oxyalkylene groups (i.e., heteric block) or
may comprise one or
more distinct blocks of each oxyalkylene group.
2 o In another embodiment of the invention, the one or more second oxide
compounds added onto
the internal block of oxypropylene groups are a mixture of ethylene oxide and
1,2-butylene oxide.
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7
2r932~2
In another advantageous embodiment of the invention, the above-described
polyether polyol is
terminated with a block of oxyalkylene groups which would yield primary
hydroxyl functionalities,
such as ethylene oxide.
Other embodiments and more preferential ranges are discussed further below in
detail. The
polyether polyols of the invention have at least one of the following
advantages and, in preferred
embodiments, simultaneously possess all of the following advantages: they have
a degree of
unsaturation of 0.06 meq/g of polyol or less, they are not dependent upon the
kind of catalyst or kind
of initiator employed to achieve the stated reduction in the degree of
unsaturation, the polyethers used
in sealant applications have a CI of 25°C or less, the polyethers have
equivalent weights of at least
1500, and they are suitable for the preparation of elastomers, sealants, and
adhesives having high
elongation tensile strength, and modulus at 100 and 300 percent elongation.
DETAILED DESCRIPTION OF THE INVENTION
The polyoxyalkylene polyethers of the invention contain a nucleus of an
initiator compound, an
internal block of oxypropylene goups, and a second block of oxyalkylene groups
containing an
oxyalkylene group derived from a Ca or higher alkylene oxide, in the stated
sequential order. The
polyoxyalkylene polyethers of the invention have a degree of unsaturation of
0.06 'meq KOIi/g of
polyol or less. Surprisingly, this low degree of unsaturation can be attained
in the manufacture of high
equivalent weight polyethers, (such as an equivalent weight of at least 1500),
in the presence of
conventional catalysts such as sodium and potassium hydroxides. Prior to
discussing the structure and
2 o method of preparation of the inventive polyethers, a brief overview of
some terms as used throughout
the specification and means for making calculations are now explained in
further detail.
The polyoxyalkylene polyether polymers of this invention are mixtures of
compounds which
can be defined by equivalent weight and weight percent of oxyalkylene groups.
If the amount of
8
~~.93~~~
alkylene oxide reacted onto an initiator is relatively large, one does not
obtain uniform molecular
compounds having the same defined number of oxyalkylene groups; but rather,
one obtains a mixture
of closely related homologues wherein the statistical average number of
oxyalkylene groups equals the
number of moles of alkylene oxide added in the manufacturing process. Thus,
one means of
calculating the weight percent of oxyalkylene groups in the polyoxyalkylene
polyether is by adding the
number of moles, or the weight of, the particular alkylene oxide added to
create the desired block. The
equivalent weight of a chain within the polyether polymer can also be
calculated by adding the total
weight of the particular alkylene oxide charged divided by the functionality
of the initiator molecule.
The polyoxyalkylene polyethers of this invention are "block" polymers of
alkylene oxides. The
1 o polyethers of this invention contain a block of oxyalkylene groups in a
chain connected to a block of
different oxyalkylene groups in the chain to provide a conjugated unit
stricture necessary for imparting
both hydrophobic and hydrophilic properties to the polymer. A block of
oxyalkylene groups is
typically thought of as containing the same type of oxyalkylene moieties, for
example, a block of pure
oxypropylene groups or a block of pure oxyethylene groups. In this invention,
however, there may
also be provided a "block" of a mixture of different oxyalkylene groups
distributed in random order.
The different oxyalkylene groups are randomly distributed, however, within the
parameters of a
discreet block rather than throughout the whole polymer chain.
The degree of unsaturation can be determined by reacting the polyether polymer
with mercuric
acetate and methanol in a methanolic solution to release the
acetoxymercuricmethoxy compounds and
2 o acetic acids. Any left over mercuric acetate is treated with sodium
bromide to convert the mercuric
acetate to the bromide. Acetic acid in the solution can then be titrated with
potassium hydroxide, and
the degree of unsaturation can be calculated for a number of moles of acetic
acid titrated. More
r
specifically, 30 grams of the polyether polymer sample may be weighed into a
sample flask, and 50 ml
9
2192.52.
of reagent grade mercuric acetate in methanol is added to a sample flask and
to a blank flask. The
sample is stirred until the contents are dissolved. The sample and blank
flasks are left standing for
thirty (30) minutes with occasional swirling. Subsequently, 8 to 10 gams of
sodium bromide are
added to each and stirred for two (2) minutes, after which one (1) ml of
phenolphthalein indicator is
added to each flask and titrated with standard .01 N methanolic KOH to a pink
endpoint.
The degree of unsaturation is calculated and expressed as milliequivalents per
gram:
(ml KOH sample - ml KOH blank ) x N KOH
- - Acidity (A) as meq/g.
weight of sample
0
The acidity correction is made only if the acid number of the sample is
greater than 0.04, in which case
it is divided by 56.1 to give meq/g.
The hydroxyl number of the polyether polyol can be experimentally measured by
standard
titration methods. Once the hydroxyl number has been measured by titration,
the number average
molecular weight of the resulting polyether polymer can be calculated by the
expression:
OH = (f) 56,100/M.W.
where f is the nominal functionality of the polymer based on the functionality
of the initiator molecule.
The compatibility index is measured by heating the polyether polymer in a
50:50 wt. ratio of
2 0 water to reagent grade isopropanol solution. 25 grams of the polyether
polymer is added to a test tube.
Then, 25 ml of the water~sopropanol solution is added and the test tube is
immersed in a water bath.
The mixture in the test tube is stirred at 300 rpm. If the mixture in the test
tube is turbid at room
temperature, the water bath is replaced with an isopropanol dry ice bath until
the mixture in the test
tube clears up. For CI's at below 15°C, the test tube is allowed to
warm in air. If the expected CI is
2 5 above 15°C, a water bath is used which is heated at a rate such
that the bath temperature is about 3°C
' r
higher than the temperature of the mixture in the test tube. In either case,
as the CI value is
- z~s3z~s~
approached, the mixture in the test tube will turn cloudy. Shortly after
cloudiness, the mixture will turn
hazy, or form discreet particles of a separate phase. This is the CI
temperature.
Within the structure of the polyoxyalkylene polyether, there is first provided
a nucleus of an
initiator compound. The initiator compound contains at least two hydrogen
atoms reactive to alkylene
oxides. Specifically, the reactive hydrogen atoms on the initiator compound
should be sufficiently
labile to open up the epoxide ring of ethylene oxide. The initiator compound
has a relatively low
molecular weight, generally under 400, more preferably under 150. The
initiator compound usually has
from 2 to 6 carbon atoms.
Examples of initiator compounds useful in the practice of this invention
include, but are not
limited to, ethylene glycol, propylene glycol, diethylene glycol, dipropylene
glycol, 2,3-butylene glycol,
1,3-butylene glycol, 1,5-pentanediol, 1,6-hexanediol, glycerol, trimethylol
propane, sorbitol, sucrose,
and the like. Another class of reactive hydrogen compounds that can be used
are the alkyl amines and
alkylene polyamines having at least two reactive hydrogen atoms, such as
methylamine, ethylamine,
propylamine, butylamine, hexylamine, ethylenediamine, diethylenediamine, 1,6-
hexanediamine,
diethylenetriamine, glycerin (glycerol), pentaerythritol, and the like, and
mixtures of any of these. Also,
such cyclicamines such as piperazine, 2-methylpiperazine, 2,5-
dimethylpiperazine and TDA can also be
used. Amides constitute a further class of such reactive hydrogen compounds,
such as acetamide,
succinamide, and benzene sulfonamide. A still further class of such reactive
hydrogen compounds are
the di- and polycarboxylic acids, such as adipic acid, succinic acid, glutaric
acid, aconitic acid,
2 0 diglycolic acid, and the like. The initiator can also be one containing
different functional groups having
reactive hydrogen atoms, also, such as citric acid, glycolic acid,
ethanolamine, and the like.
One of the advantages of the invention lies in the preparation of low
unsaturation polyols using
hydroxyl functional initiator compounds. In the preparation of sealants,
adhesives, and elastomers, it is
11
2193~~~.
preferred that the initiator compound has two or three active hydrogen atoms;
and it is more preferred
that these active hydrogen atoms are hydroxyl functionalities.
A mixture of initiator compounds may be used to adjust the functionality of
the initiator to a
number between whole numbers. In the preparation of elastomers, it is
desirable to employ an initiator
having a functionality as close to 2 as possible; while in the preparation of
sealants, it is desirable to
employ an initiator having a functionality within the range of 2.3 to 3Ø
Therefore, if one desires to
manufacture an elastomer having only a slight degree of crosslinking, a high
proportion of an initiator
having a functionality of 2, to which is added relatively small amounts of tri-
or higher functional
initiator compounds, may be mixed together to arnve at an initiator having an
average functionality
close to 2, such as from 2.0 to less than 2.3. On the other hand, a larger
proportion of tri- or higher
functional initiator compounds can be mixed with a di-functional initiator
compound when a higher
degree of crosslinking is desired, such as in the preparation of sealants and
adhesives. As noted above,
it is most preferred that all such functionalities be hydroxyl
functionalities.
The polyether of the invention may be prepared by the addition reaction
between a suitable
initiator compound directly or indirectly with a defined amount of propylene
oxide to form an internal
block of oxypropylene groups, followed by further direct or indirect addition
of one ~or more second
oxides including a C4 or higher alkylene oxide.
In one embodiment of the invention, propylene oxide is added to and reacted
directly with a di-
or higher functional initiator compound through the reactive hydrogen atom
sites to form an internal
2 o block of polyoxypropylene groups. The structure of such an intermediate
compound can be
represented according to the following formula:
R ~ ~C31~0)w ]-Z
' r
12
21925'2
wherein R is the nucleus of the initiator; w is an integer representing the
number of oxypropylene
groups in the block such that the weight of the oxypropylene groups is from 25
to 80 weight percent,
based on the weight of all alkylene oxides added and initiator; and z is an
integer of 2 or more
representing the number of reactive sites on the initiator molecule onto which
are bonded the chains of
oxypropylene groups.
The internal block of oxypropylene groups imparts hydrophobic characteristics
to the polymer,
which is essential to repelling water and avoiding the swelling and
degradation of elastomers, sealants,
and adhesives made with the polyether polymer. The hydrophobic characteristic
of a polymer can be
1 o measured by the compatibility index.
The block of oxypropylene groups is internal to the polyoxyalkylene polyether
polymer. By an
internal block is meant that the block of oxypropylene groups should be
structurally located between
the nucleus of the initiator compound and another block of one or more
different kinds of oxyalkylene
groups. It is within the scope of the invention to interpose a block of
different oxyalkylene groups
between the initiator nucleus and the block of oxypropylene groups, especially
if the different
oxyalkylene groups are also hydrophobic. In a preferable embodiment, however,
the internal block of
oxypropylene goups is directly attached to the nucleus of the initiator
compound through its reactive
hydrogen sites. This preferred embodiment may be carried out by directly
reacting the initiator
compound with propylene oxide.
2 0 The internal block of oxypropylene groups consists essentially of
oxypropylene groups,
meaning that substantially all of the alkylene oxides added to form the.
internal block are propylene
oxide compounds. It is within the spirit and scope of the invention that the
internal block of
oi~ypropylene groups may contain a minor number of different oxyalkylene
groups, such as
13
21~~~5~
oxyethylene or oxybutylene groups. The internal block of oxypropylene groups
is designed to impart
hydrophobic characteristics to the polyoxyalkylene polyether polymer in order
to repel water, and
reduce the swelling and degradation of elastomers, sealants, and adhesives
made with such polyethers.
While alkylene oxides which would impart hydrophilic properties to the
polyether polymer can be
tolerated in small amounts, they should be avoided to the extent that the
hydrophobicity of the polymer
is so impaired that the resulting elastomers, adhesives, or sealants made
therewith show signs of water
swelling and degradation. Further, while oxybutylene groups are hydrophobic, a
commercial
advantage is achieved by using as much propylene oxide as possible without
significantly lowering the
functionality of the polyether polymer. In general, 5 weight percent or less
of all the propylene oxide
1 o added as an internal block can be in the form of different alkylene
oxides, such as ethylene oxide,
butylene oxide, tetrahydrofuran, etc. In a more preferable embodiment, less
than 2 weight percent
based on the internal block is made up of oxyalkylene groups which are
different from oxypropylene
groups. In the most preferred embodiment, the internal block consists solely
of oxypropylene groups.
The polyoxyalkylene polyether polymer may comprise more than one internal
block of
oxypropylene goups. Whatever the number of internal blocks of oxypropylene
groups located in the
polyether polymer structure, the total weight of oxypropylene groups is
advantageously from 25
weight percent to 80 weight percent based on the weight of all oxyalkylene
compounds added to the
initiator and the initiator itself.
In the method of the invention, an initiator compound is reacted in sequential
order with
2 o propylene oxide, followed by a reaction with one or more second oxides. By
"sequential order" is
meant only that there should appear at least one block of oxypropylene groups
internal to the polyether
polymer, followed by directly adding onto the internal block one or more
second oxides as defined
r
herein, or indirectly adding onto the internal block of oxypropylene groups
one or more second oxides
14
21~~2~~
as defined herein, through other alkylene oxides. In a preferred embodiment of
the invention, the
oxypropylene goups are attached to the initiator compound through its alkylene
oxide reactive sides,
and the one or more second oxides comprising a C4 or higher alkylene oxide are
directly added onto
the internal block of oxypropylene goups to form a second block of oxyalkylene
goups directly
attached and bonded to the internal block of oxypropylene goups.
The block of oxypropylene goups is from 25 weight percent to 80 weight percent
based upon
the weight of all oxyalkylene compounds added to the initiator compound and
the initiator. This
weight percentage can be determined experimentally by gas chromatography or on
a calculated basis
from the actual weight of propylene oxide groups added in the manufacture of
the polyether polymer,
to assuming the reaction time, temperature, and pressures are set for reacting
out all the propylene oxide
added in a reaction vessel for the manufacture of the polyether. The amount of
propylene oxide is at
least 25 weight percent. Adding propylene oxide in the amounts of less than 25
weight percent, or a
polyether polymer containing less than 25 weight percent of oxyethylene goups,
renders the polyether
polymer insufficiently hydrophobic for many applications and causes the
mechanical properties of
elastomers and sealants made with the polyether to degade. The upper limit of
propylene oxide
addition for most embodiments, or the upper limit of oxypropylene goups in the
pqlyether polymer
structure, is 80 weight percent. At amounts Beater than 80 weight percent, a
significant amount of
tenwinal allylic unsaturation develops in the manufacture of higher equivalent
weight polyether
polymers. In a more preferable range, the relative amount of oxypropylene
groups ranges from 60 to
2 0 75 weight percent.
In building the block of oxypropylene groups, terminal allylic unsaturation
develops as the
equivalent weight of the block of oxypropylene goups grows; and the degree of
unsaturation becomes
r
more pronounced as the equivalent weight increases. While the reaction
conditions and types of
~19~252.
inv~nhon, the ohypropyhne~ s~~7nps are attached to the initiator c~ompaund
through. its alti-y~lene oxide
rea";zir~e sides, xnd the one or n~or~ secont9 c~xicic.s rx~rr,prisi.a~ a ~':~
or hiker alkylF~t,.e oxide we
dir~~tly added onto the internal block c~f. t~xy~prop_ylene gi"oups tc~ form.
a second black of oxyatl~yl~ne
groups directly aitaciW and banded u; the arjtertial lalctck of ox.ypropylene
~-coups.
'fhe block of oxypropylene ,coups is fzum Z5 weight portent to 8U weir;ht
percent based upon
th.e weight of all uxyalkylene cotnpcmnds added to floe initiator compound and
th.e initiator- This
weight percentage can be deteinnined experimentally by ~ra~, chromatography or
on a calculated basis
&°otn the a~2ual weight t~f prt~pylel,e oxide groups a~dclecl in the
manufachtre of the polyether polymer,
asstutiing the reataion time, temperature, ax,d pressures are set for reacting
out all tb.e propylene ~o:!rido
added in a reaction vessel for the mannfarture ~~f the polyether The amount of
propylFne oxide is ai
feast 2~ weight percent. Adding prupyl~r~e t~xida irt tlae amounts of less
than 25 weipt percent, or a
polyether pol.ytnes~ containin~~ less Than 25 w~i~,ht percent of oxyethylene
~rc~ups, renders the
polyetb.er polymer insufficiently hydrophobic for many applicatit,ns at,d
i:auses the miechanical
properties of elastomers and sealarats made witr~ floe polyether fo de~;rade_
~i"be upper limit ofi
~.5 propylene: oxide addition t-or mast emt~otiiments, tar the upper limit of
o~vpropylene ~rattp5 tn the
polyether polymer structure, is SO weight percent. At amounts water than 80
weiglat percent, a
signilican arnourri of terminal ellylic unsat~-ration develops in the
tz,.anufacture of higher eqtaivalent
'weight pUlyether pcyly-n~ers- In a. more preferable range, the relative
amount of ax~~z-apylene ~-aups
ranges from 6t) to 75 weight perCent-
In building the black of oxypropylEne groups, terminal allylic unsaturation
develops as the
equivalent weight of tl~~ block. ok ol,.ypropylene Groups bows; and the degree
of unsatura,tian
becomes more pronounced as the eqsnivalent weight increases. While the
reaction s~riditions and
16
z19325~
t~p~ c~f ca~Iy;ts ernplc;y~ influeiiex 'dm tie~ri~; c~f urt~turation
developc~i for, any given polyefher
prlyrtier, one begltLS t0 notrcl'. ur1$3~~,r1'dtjoll devefopin,~ llsil7~.g
ConveiltiOna.l KdI~ Cat$lySt<5 when the
equivalent weight of the block of oxypropylene groups is about 8U0 or zr~ore
with rrrore prpnounced
effeub when the equivalent weight of oxypropylene groups is about i,00U trr
more. When the
ecluivaient weight o~ the block of oxyprcrpyler~e soups is about 1,700 or
more, such a. lame amount
of trrmitial allylic un~aturation develops that the meehaalic.~al properties
of ehstonners, sealants, and
adhesive made with these polyether polymers are noticeable deteriorated.
Tl~er~fore, in one
embodiment of thc: invention, suffiicierrt propylene oxide is added to form a
block of oxy~rrc~pylene
groups such that the equivalent wei~~ t of the block. is at least about 800
anal no mare than about
i Q l, 700, more preferably born al.~out l,t?O() to abort .1, i00,
The object of adding only a limited number o~ propylene oxide compounds is to
avoid a
significant buildl3p of terminal unsatirration. lrr some embodiments, e.g.,
where cesiatn hydroxide
catalysts are used, however, it is not necessary tar discontinue propylene
oxide addition until a de~~e~
of terminal uasaturatian dt~velops beyond a cor~~ain point. '1'here:Fore,
ratb.er tr~an tlis~"ontinuin g
addition of propylene oxide within a rrlinimum equirralent weight of about 800
or more to a.
maximum of about 1700, addition of propylene oxide may crease when tlxe degee
of unsah.rratic~n of
the growing bloclc of o~:y~ropylene oxic~l~ groups t.S nleastlreci at 0Ø10
me~ig of polyol or .more
'Thus, the addititrn of the one of more second oxides in this embodirrtent may
ec.~mnz~:nee cvlaen 0.01
meqJg of polyol uasat~~ration or mare devolc~ps, er inn the alternative,
rNhen. the equiv4~Jer!t we.i~t of
20 the-block of oxypropylene groups is about 1,700, must preferably, 1,300.
After the internal block of or,ypropylene goups is n5~.r7ufaCtured, one or
more second oxides,
at least one of which is a t:,r or higher alkylene oxide, are added directly
or indirectly to th.e internal
I'7
In the case where a mixture of alkylene oxides are employed, such as ethylene
oxide and 1,2-
butylene oxide, the second block will be made up of a mixture of oxyethylene
and oxybutylene groups
in random distribution. Such a structure can be represented by the following
block formula:
R C (~3H6o~ ~~o~ (~2H4o~)a lz H
where R, w, x, and z are as. stated above, y is an integer representing the
number of oxyethylene
groups; s is an integer, preferably 1, representing the number of blocks of
oxybutylene-oxyethylene
mixtures, and each s block is a random mixture of oxybutylene and oxyethylene
groups the s block
being attached through a bond to the block of oxypropylene groups.
The total amount of the one.or more second alkylene oxides added in the
manufacture of the
to polyether polyol and the amount of the resulting second block of
oxyalkylene groups is effective to
reduce the degree of unsaturation of the polyether polyol to 0.06 meq/g of
polyol or less. By the term
"reduce" is meant a reduction in unsaturation compared to a polyether polymer
made with the same
initiator, under the same reaction conditions and catalysts, and made to the
same equivalent weight of
the final polyether polymer, but using solely propylene oxide as the alkylene
oxide added to the initiator
molecule. A particularly advantageous feature of the invention lies in the
flexibility of adjusting the
degree of unsaturation merely by adding a Beater amount of the one or more
second bxides as defined
herein rather than changing catalyst types or reaction conditions, which are
quite expensive or time
consuming. Where the ultimate use of the polyether polymer lies in
applications benefiting from
degees of unsaturation much lower than 0.06, the one or more second alkylene
oxides may be added
2 o early when little, if any, unsaturation has developed during the
manufacture of the internal block of
oxypropylene groups. Also, more or less of the one or more second alkylene
oxide compounds may be
added to adjust the degree of unsaturation.
' r
18
z~93z~~
One of the embodiments of the invention lies in the manufacture of a polyether
polymer having
a degree of unsaturation of 0.03 or less finding beneficial use in elastomers,
without having to resort to
unusual reaction conditions or exotic and expensive catalysts, such as double
metal cyanide catalysts.
In a particularly preferred embodiment of the invention, 1,2-butylene oxide is
reacted onto the internal
block of oxypropylene groups, in amounts sufficient to reduce the degree of
unsaturation of the
resulting polyether polymer to 0.06 meq/g of polyol or less where the end use
of the polyether
polymers is in the manufacture of sealants and adhesives, and to 0.03 or less
where the end use of the
polyether polymer is in the manufacture of elastomers. The amount of 1,2-
butylene oxide to achieve
this objective is generally from at least 5 weight percent, and more
preferably at least 10 weight
l0 percent, based upon the weight of all oxyalkylene compounds added to the
initiator compound and the
initiator. Usually, no more than 20 weight percent is needed to accomplish a
reduction in unsaturation.
It is possible to reduce the degree of unsaturation of the polyether polymer
to 0.06 or less by
adding solely ethylene oxide onto the internal block of oxypropylene groups.
However, so much
ethylene oxide would have to be added to acheive a comparable molecular weight
polymer that the
polyether polymer would becpme too hydrophilic. Thus, it is critical to the
invention that the
hydrophobic C4 or higher alkylene oxides are added in significant amounts in
the 'second block of
alkylene oxides to maintain the desired hydrophobic characteristics.
Where a mixture of ethylene oxide and 1,2-butylene oxide is employed, the
relative amounts of
each alkylene oxide will depend upon the desired degree of hydrophobicity as
measured by the
2 o compatibility index.
While the particular weight ratio of 1,2-butylene oxide to ethylene oxide is
not lirriited, suitable
relative amounts of each can range from 0.5:1 to 4:1. Preferred amounts of 1,2-
butylene oxide to
' r
ethylene oxide range from about I : I to 2: I, particularly when improved
hydrophobicity of the resultant
19
CA 02193252 2003-12-10
elastomer, sealant or adhesive is desirable. The more
ethylene oxide that is added, the more hydrophilic is the
nature of the second block of one or more alkylene oxide
groups. The more C4 or h-1 des that are added in the second
block, the more hydrophobic will be the nature of the
second block of second oxyalkylene groups.
The total weight of the second block of one or
more second oxyalkylene groups will generally range from 5
weight percent to 75 weight percent, more preferably from
greater than 5 weight percent to 50 weight percent, and
most preferably from 10 weight percent to 30 weight
percent, based upon the weight of all oxyalkylene compounds
added to the initiator compound and the initiator.
The polyether polymers of the invention are
terminated with two or more isocyanate reactive hydrogens.
The reactive hydrogens may be in the form of primary or
secondary hydroxyl groups, or primary or secondary amine
groups. In the manufacture of elastomers, sealants, and
adhesives, it is often desirable to introduce isocyanate
reactive groups which are more reactive than secondary
hydroxyl groups. Primary hydroxyl groups can be introduced
onto the polyether by reacting the growing polyether
polymer with ethylene oxide. Therefore, in one embodiment
of the invention, the polyether polymer may be terminated
with a terminal block of oxyethylene groups. Alternatively,
in another embodiment, the polyether polymer of the
invention may be terminated with of a mixture of primary
and secondary terminal hydroxyl groups when a mixture of
ethylene oxide and 1,2-butylene oxide is employed in the
manufacture of the second block of one or more second
alkylene oxides. Primary and secondary amine groups can be
CA 02193252 2003-12-10
introduced onto the polyether polymer by a reductive
amination process as described in U.S. Patent No.
3,654,370.
The polyether polymer of the invention is
preferably a polyether polyol.
The polyether polyol may optionally be terminated
with a terminal block consisting essentially of oxyethylene
groups containing a primary hydroxyl group on the terminal
carbon of the terminal
20a
~1932~2
block. The weight of the Terminal block of oxyethylene groups when employed,
is at least 4 weight
percent, preferably from 10 weight percent to 25 weight percent, based upon
the weight of all
oxyalkylene compounds added to the initiator and the initiator.
In the manufacture of sealants and adhesives, the polyether polymers used will
usually have
either a low equivalent weight terminal block of oxyethylene groups or no
terminal block of
oxyethylene groups at all. Sufficient reactivity may be provided by way of
primary hydroxyl
functionality through a mixture of ethylene oxide and the Ca or higher
alkylene oxides, used in the
manufacture of the second block.. The CI of the polyether polymer for use in
these applications is
advantageously 25°C or less.
1o In the manufacture of elastomers, however, it is often desired to enhance
the reactivity of
polyether polyols. This is accomplished by terminating the polyether polymer
with a terminal block of
oxyethylene groups. While it is possible to aminate the terminal block of
oxyethylene groups, it is more
desirable to have a primary hydroxyl group attached to the terminal carbon of
the terminal block of
oxyethylene groups. The weight percent of the terminal block of oxyethylene
groups on polyether
polymers used in the manufacture of elastomers should be at least 4 weight
percent, more preferably
from 10 weight percent to 25 weight percent, based on the weight of all
oxyalkylehe groups on the
polyether polymer and the initiator.
The method of polymerizing the polyether polymers of the invention is not
limited and can
occur in one of three different ways: anionic, cationic, and coordinate
mechanisms.
2 0 Methods of anionic polymerization are generally known in the art.
Typically, an initiator
molecule is reacted with an alkylene oxide in the presence of a basic
catalyst, such as an alkoxide or an
alkali metal hydroxide. The reaction can be carried out under super
atmospheric pressure and an
T
aprotic solvent such as DMSO or THF, or in bulk.
21
CA 02193252 2003-12-10
One feature of the invention lies in the ability
to manufacture a polyether polymer having a low degree of
unsaturation and a high equivalent weight without regard to
the type of catalyst employed. For example, low degrees of
unsaturation can be obtained in high equivalent weight
polyether polymers using such conventional catalysts as
potassium and sodium hydroxide. The type of catalyst
employed is not limited by the invention. Catalysts, such
as alkali metal alkoxides, cesium based catalysts, and
double metal cyanide catalysts as described in U.S. Patent
No. 3,829,505, and the hydroxides and alkoxides of lithium
and rubidium, may be employed.
Cesium-containing catalysts include cesium oxide,
cesium acetate, cesium carbonate, cesium alkoxides of the
Cl-Cg lower alkanols, and cesium hydroxide. Other useful
catalysts include the oxides, hydroxides, hydrated
hydroxides, and the monohydroxide salts of barium or
strontium.
Suitable alkali metal compounds include compounds
that contain sodium, potassium, lithium, rubidium, and
cesium. These compounds may be in the form of alkali metal,
oxides, hydroxides, carbonates, salts of organic acids,
bicarbonates, natural minerals, silicates, etc. and
mixtures thereof. Suitable alkali earth metal compounds and
mixtures thereof include compounds which contain calcium,
strontium, magnesium, beryllium, copper, zinc, titanium,
zirconium, lead, arsenic, antimony, bismuth, molybdenum,
tungsten, manganese, iron, nickel, cobalt, and barium.
Suitable ammonium compounds include, but are not limited
to, compounds which contain ammonium radical, such as
ammonia, amino compounds, e.g., urea, alkyl ureas,
22
CA 02193252 2003-12-10
dicyanodiamide, melamine, guanidine, aminoguanidine;
amines, e.g., aliphatic amines, aromatic amines; organic
ammonium salts, e.g., ammonium carbonate, quaternary
ammonium hydroxide, ammonium silicate, and mixtures
thereof. The ammonium compounds may be mixed with the
aforementioned basic salt-forming compounds. Other typical
anions may include the halide ions of fluorine, chlorine,
bromine, iodine, or nitrates, benzoates, acetates,
sulfonates, and the like.
22a
~1~~25~
The reaction conditions can be set to those typically employed in the
manufacture of
polyoxyalkylene polyether polyols. Generally, from 0.005 percent to about 5
percent, preferably from
0.005 to 2.0 percent, and most preferably from 0.005 to 0.5 percent by weight
of the catalyst relative
to the polyether polymer is utilized.
Any catalyst left in the polyether polymers produced according to the
invention can be
removed by any of the well-known processes described in the art, such as by
acid neutralization,
adsorption, water washing, or ion exchange. Examples of acids used in the
neutralization technique
include solid and liquid organic acids, such as acetic acid and 2-
ethylhexanoic acid. For ion exchange,
phosphoric acid or sulfuric acid may be used. Extraction or adsorption
techniques employ activated
1 o clay or synthetic magnesium silicates. It is desirable to remove metal
cationic contents down to less
than 500 ppm, preferably less than 100 ppm, most preferably from 0.1 to 5 ppm.
As for other processing conditions, the temperature at which polymerization of
the polyether
polymers occurs can range from 80°C to 160°C, preferably from
100°C to 140°C. At temperatures
above 160°C, the product might discolor; and the product tends to
develop a higher degree of
unsaturation. The reaction can be carried out in a columnar reactor, a tube
reactor, or batchwise in an
autoclave. In the batch process, the reaction is earned out in a closed vessel
under pressure which can
be regulated by a pad of inert gas and the feed of alkylene oxides into the
reaction chamber. Generally,
the operating pressures produced by the addition of alkylene oxide range from
10 to 80 psig.
Generating a pressure over 100 psig increases the risk of a runaway reaction.
The alkylene oxides can
2 o be fed into the reaction vessel as either a gas or a liquid. The contents
of the reaction vessel are
vigorously agitated to maintain a good dispersion of the catalyst and uniform
reaction rates throughout
f the mass. The course of polymerization can be controlled by consecutively
metering in each alkylene
oxide until a desired amount has been added. Where a block of a random or a
statistical distribution of
23
' ~~9~2~2
1,2-butylene oxide and other alkylene oxides are desired in the polyether
polymer, the alkylene oxides
may be metered into the reaction vessel as mixtures. Agitation of the contents
in the reactor at the
reaction temperature is continued until the pressure falls to a low value. The
final reaction product may
then be cooled, neutralized as desired, and removed.
The polyether polymers of the invention can be prepared in a batchwise process
according to
the following description. It should be understood that this is merely one
method for preparing the
polyether polymers of the invention, and other methods would include preparing
the polyether
polymers in a continuous reactor or a tubular reactor.
In a batch reaction, the charge of initiator and catalyst solution are weighed
out and added to
1 o an autoclave, which is subsequently sealed and purged with nitrogen.
Instead of weighing out and
adding an initiator compound, an intermediate low molecular weight pre-made
polyether polymer of
propylene oxide added onto the initiator compound can be added to the
autoclave. The scope of the
invention, however, includes the addition of propylene oxide onto an
initiator, whether such addition
occurs solely in the main reactor or in two stages by the formation of an
intermediate with subsequent
addition or more alkylene oxide, in the main reactor.
Residual water contained in the initiator or the intermediate low molecular
iweight polyether
polymer, and water formed by the reaction of the hydroxide anion on the
catalyst and the hydrogen
atom on the initiator or intermediate compound, should be stripped from the
reaction mixture.
Stripping should occur at approximately the boiling point of water and at a
reduced pressure.
2 0 Subsequently, the autoclave may be re-pressurized with nitrogen and slowly
heated to a reaction
temperature appropriate for the addition of propylene oxide. Typically, this
reaction terriperature will
range from about 100°C to 120°C. Propylene oxide is then added
slowly over a period of time without
r
letting the pressure build up beyond about 80 psig, and preferably not more
than 90 psig. The feed rate
24
~1~3~5~.
of propylene oxide should be sufficiently slow to avoid terminal allylic
unsaturation to the extent
possible, yet added sufficiently quickly to optimize production time. The time
can vary from one hour
to ten hours depending on the size of the reaction vessel and the overall
amount of propylene oxide
added. Propylene oxide can be added continuously or step wise, and in a linear
or at an exponentially
decreasing or increasing rate.
The contents of the autoclave continue to be heated for a time sufficient to
react out
substantially all of the propylene oxide. Subsequently, the autoclave should
be evacuated to purge any
unreacted propylene oxide, after which nitrogen is re-introduced to pressurize
the reactor once again.
The reactor then may be heated at the same or higher temperature than used for
the addition of
propylene oxide when adding 1,2-butylene oxide and/or mixtures of 1,2-butylene
oxide and other
alkylene oxides which do not tend to form terminal allylic unsaturation. Since
the alkylene oxides
added at this step do not form allylic unsaturation, the reaction temperature
and rate of addition may be
higher than the reaction temperature and feed rate, set during propylene oxide
addition. Once again, at
this stage, the added alkylene oxides are reacted out over a period of time,
the autoclave is evacuated
to purge any unreacted alkylene oxides, and re-pressurized with nitrogen and
heated during the
addition of pure ethylene oxide if one desires to produce a polyether polymer
having an oxyethylene
cap. Once all the alkylene oxides have been added and reacted, the autoclave
is cooled and evacuated,
and the contents are subsequently discharged to a container flushed with an
inert gas.
The residual catalysts and the polyols can be neutralized by an organic acid
such as phosphoric
2 0 acid, sulfuric acid, acetic acid, solid organic acids; removed by the
carbon dioxide finishing procedure
described in Japanese Patent SS-092773-A; or treated with an adsorber such as
magnesium silicate or
-an activated clay. Any residual water remaining after removal of the catalyst
should be stripped from
r
the polyether polymer under an inert gas. Subsequently, the polyether polymer
can be cooled and
219 3 2 5'~
stabilized with well-known conventional polyether polyol stabilizers. Once
stabilized, the polyether
polymer may be exposed to atmospheric oxygen.
The invention further relates to new elastomers, sealants and adhesives. The
polyether
polymers of the invention can be used in a wide variety of applications, and
the equivalent weight of the
polyether polymer will vary depending upon the application. Since terminal
allylic unsaturation is not
very noticeable at equivalent weights of less than 800, the polyether polymers
usually will have
equivalent weights of 1000 or more. Depending upon the particular application,
the equivalent weight
of the polyether polymer can include weights of 1300 or more, or 2000 or more.
Nominal hydroxyl numbers of the polyether polymers are not limited. For most
applications,
1o however, the nominal hydroxyl numbers will range from 15 to 57, preferably
from 15 to 38.
In one embodiment of the invention, there is provided an elastomer made with a
polyoxyalkylene polyether polymer having within its polymer structure a
nucleus of an initiator
compound, an internal block of oxypropylene goups; and a second block of
oxyalkylene groups,
wherein the internal block of oxypropylene groups is between the nucleus of
the initiator and the
second block of oxyalkylene groups, and further where the second block of
oxyalkylene groups
4
contains at least one derivative of a C4 or higher alkylene oxide, and the
amount of the internal block of
oxypropylene groups is at least 800 equivalent weight based on the weight of
all oxyalkylene groups in
the polyether. The polyether polymer is preferably a polyether polyol. The
initiator compounds used
in the manufacture of this polyether polymer for use in elastomers are
difunctional compounds or a
2 0 mixture of difunctional and higher functional compounds such that the
mixture would have an average
functionality of less than 2.3. It is more preferred that the average
functionality of the inutiator
compounds is 2.1 or less, and most preferably 2Ø
f
26
- 2~93~5~
The functionalities can be set by polymerizing alkylene oxides onto a mixture
of initiators, or
polymerizing alkylene oxides onto a single initiator and mix the resulting
polyether polymer with other
polyether polymers made using different initiators.
The elastomers may be thermoset or thermoplastic. Elastomers of the invention
can be made in
the form of films or sheets extruded to any desired thickness. Such films and
sheets find applications
in conveyor belts, the transport of sand and stone slurry, applications where
low permeability is
required, abrasion resistant coatings, textile lamination, protective
coatings, and liners for hoses such as
fire hoses. Other applications include using elastomers for the outer material
of ski boots, shoe soles,
ice hockey boots, automotive applications such as exterior automotive body
parts, bushings, tires,
1 o wiper blades, gaskets for wheel components, tubes, membranes, and seals.
Still further applications
include wheels, vibration dampers, screens for sorting materials, cable
sheaving, medical and food
industries, hammers, gears, pump chambers, rollers, impellers, door seals, and
the like.
Various applications for the sealants described herein are for windshields,
hem, thermal brakes,
airport runways, highways, joints and building construction, and waterproofing
membranes for decks
and bridges.
The polyurethane elastomers, sealants, and adhesives of the invention can
be,prepared by the
prepolymer technique or in a one-shot process. The elastomers of the invention
can be prepared by a
reaction injection molding technique, or in a cast process wherein the
polyurethane forming ingedients
are mixed together and poured into a heated mold into pressure. Other
techniques include
2 o conventional hand-mixed techniques and low pressure or high pressure
impingement machine mixing
techniques followed by pouring polyurethane forming ingredients into molds.
In a one-shot process, the polyether polymer of the invention, catalysts, and
other isocyanate
reactive components ("B-side" components) are simultaneously reacted with an
organic isocyanate
27
2~932~~
("A-side" components). Once the B-side components are mixed together, the
urethane reaction
commences; and the ingredients are poured or injected into molds. In a
prepolymer technique, all
or a portion of the polyether polymer and/or other isocyanate reactive polyols
are reacted with a
stoichiometric excess of the organic isocyanate to form an isocyanate-
terminated prepolymer. The
prepolymer is then reacted as an Aside component with any remaining B-side
components to form a
polyurethane elastomer, sealant, or adhesive. In some cases, all of the
isocyanate reactive B-side
components are reacted with a stoichiometric excess of organic isocyanate to
form a one-component
sealant or adhesive. Such isocyanate terminated prepolymers typically have a
low free NCO content of
1 weight percent to 15 weight percent. The one-component prepolymers may be
cured by water in the
1 o form of moisture in the atmosphere or by further addition of water. In
other cases, only a portion of
the polyether polymer or other polyols are reacted with the stoichiometric
excess of organic isocyanate
to form an isocyanate terminated prepolymer, which is subsequently reacted
with the remainder of the
B-side components, including polyols, as a two-component elastomer, sealant,
or adhesive.
The free NCO content of the prepolymers used to make the elastoiners,
sealants, and adhesives
of the invention can range from 0.5 weight percent to 30 weight percent,
preferably from 1 weight
percent to 15 weight percent, more preferably from 1 weight percent to 10
weight percent.
Other ingredients in the B-side polyol composition, besides the polyether
polymer of the
invention, may include other polyols, chain extenders or curing agents,
catalysts, fillers, pigments, u-v
stabilizers, and the like.
2 0 In addition to using the polyoxyalkylene polyether polymer having a low
degree of unsaturation
in the polyol composition for the manufacture of elastomer, sealant, or
adhesive, other polyols may be
mixed into the polyol composition. For example, the addition of polyester
polyols may be added to
r
improve the mechanical properties of an adhesive. Polyester polyols tend to
improve the tensile
28
- 2193~~2
strength and modulus of the urethane polymer, which are important
considerations in the field of
adhesives. For sealants, however, it is preferred to use polyether polyols
which are hydrolytically stable
and process well due to their lower viscosities. Other polyols that can be
employed in addition to the
polyoxyalkylene polyether polymers of the invention are hydroxyl terminated
hydrocarbons, such as
polybutadiene polyols, where a high degree of hydrophobicity is desired.
Castor oils and other natural
oils may also be employed. In addition, polycaprolactones can be used to
increase the tensile strengths
of sealants. Other polyether polyols may be added, and it is preferred that
these polyether polyols have
a low degee of unsaturation to optimize the mechanical properties of the
product. For example, those
polyether polyols made with either amorphous or crystalline DMC catalysts are
suitable, as well as
l0 polyether polyols catalyzed by cesium hydroxide.
One-component sealants or adhesives are typically cured by moisture from the
air. Two-
component sealants, adhesives, and elastomers are typically cured by chain
extenders with compounds
containing isocyanate reactive hydrogen. Chain extenders may be, and are
typically, employed in the
preparation of polyurethane elastomers, sealants, and adhesives. The term
"chain extender" is used to
mean a relatively low equivalent weight compound, usually less than about 250
equivalent weight,
having a plurality of isocyanate reactive hydrogen atoms.
Chain-extending agents include water, hydrazine, primary and secondary
aliphatic or aromatic
diamines, amino alcohols, amino acids, hydroxy acids, glycols, or mixtures
thereof. A preferred group
of alcohol chain-extending agents includes water, ethylene glycol, 1,3-
propanediol, 1,4-butanediol,
2 0 1,10-decanediol, o,-m,-p-dihydroxycyclohexane, diethylene glycol, 1,6-
hexanediol, glycerine;
trimethylol propane, 1,2,4-, 1,3,5-trihydroxycyclohexane, and bis(2-
hydroxyethyl) hydroquinone.
Examples of secondary aromatic diamines are N,N-dialkyl-substituted aromatic
diamines,
' ;
which are unsubstituted or substituted on the aromatic radical by alkyl
radicals, having 1 to 20,
29
J
219322
preferably 1 to 4, carbon atoms in the N-alkyl radical, e.g., N,N-diethyl-,
N,N-di-sec-pentyl-, N,N-di-
sec-hexyl-, N,N-di-sec-decyl-, and N,N-dicyclohexyl-p- and m-phenylenediamine,
N,N-dimethyl-,
N,N-diethyl-, N,N-diisopropyl-, N,N,'-disec-butyl- and N,N-dicxclohexyl-4,4'-
diaminodiphenylmethane and N,N-di-sec-butylbenzidine.
The amount of chain extender used varies somewhat on the desired physical
properties of the
elastomer or sealant. A higher proportion of chain extender and isocyanate
provides the elastomer or
sealant with greater stiffness and heat distortion temperature. Lower amounts
of chain extender and
isocyanate provide a more flexible elastomer or sealant. Typically, about 2 to
70, preferably about 10
to 40, parts of the chain extender are used per 100 parts of polyether polymer
and any other higher
1 o molecular weight isocyanate reactive components.
Catalysts may be employed which greatly accelerate the reaction of the
compounds containing
hydroxyl groups and with the modified or unmodified polyisocyanates. Examples
of suitable
compounds are cure catalysts which also function to shorten tack time, promote
green strength, and
prevent foam shrinkage. Suitable cure catalysts are organometallic catalysts,
preferably organotin
catalysts, although it is possible to employ metals such as lead, titanium,
copper, mercury, cobalt,
nickel, iron, vanadium, antimony, and manganese. Suitable organometallic
catalysts, exemplified here
by tin as the metal, are represented by the formula: R"Sn[X-R'-Y)2, wherein R
is a C,-Cs alkyl or aryl
group, R' is a Co-C,g methylene group optionally substituted or branched with
a C1-C4 alkyl group, Y
is hydrogen or an hydroxyl group, preferably hydrogen, X is methylene, an -S-,
an -SRZCOO-, -SOOC-
2 0 , an -03S-, or an -OOC- group wherein RZ is a C,-C4 alkyl, n is 0 or 2,
provided that R' is Ca only when
X is a methylene group. Specific examples are tin (II) acetate, tin (II)
octanoate, tin (II) ethylhexanoate
and tin (II) laurate; and dialkyl (1-8C) tin (I~ salts of organic carboxylic
acids having 1-32 carbon
' r
atoms, preferably 1-20 carbon atoms, e.g., diethyltin diacetate, dibutyltin
diacetate, dibutyltin diacetate,
X193252
. dibutyltin dilaurate, dibutyltin maleate, dihexyltin diacetate, and
dioctyltin diacetate. Other suitable
organotin catalysts are organotin alkoxides and mono or polyalkyl (1-8C) tin
(I~ salts of inorganic
compounds such as butyltin trichloride, dimethyl- and diethyl- and dibutyl-
and dioctyl- and diphenyl-
tin oxide, dibutyltin dibutoxide, di(2-ethylhexyl) tin oxide, dibutyltin
dichloride, and dioctyltin dioxide.
Preferred, however, are tin catalysts with tin-sulfur bonds which are
resistant to hydrolysis, such as
dialkyl (I-20C) tin dimercaptides, including dimethyl-, dibutyl-, and dioctyl-
tin dimercaptides.
Tertiary amines also promote urethane linkage formation, and include
triethylamine, 3-
methoxypropyldimethylamine, triethylenediamine, tributylamine,
dimethylbenzylamine, N-methyl-, N-
ethyl- and N-cyclohexylmorpholine, N,N,N,N'-tetramethylethylenediamine,
N,N,N,N-
tetramethylbutanediamine or -hexanediamine, N,N,N-trimethyl isopropyl
propylenediamine,
pentamethyldiethylenetriamine, tetramethyldiaminoethyl ether,
bis(dimethylaminopropyl)urea,
dimethylpiperazine, 1-methyl-4-dimethylaminoethylpiperazine, 1,2-
dimethylimidazole, 1-
azabicylo[3.3.0]octane and preferably 1,4-diazabicylo[2.2.2]octane, and
alkanolamine compounds,
such as triethanolamine, triisopropanolamine, N-methyl- and N-
ethyldiethanolamine and
dimethylethanolamine.
To prevent the entrainment of air bubbles in the sealants or elastomers, a
batch,mixture may be
subjected to degassing at a reduced pressure once the ingredients are mixed
together. In a degassing
method, the mixed polyurethane formed ingredients can be heated under vacuum
to an elevated
temperature to react out or volatize residual water. By heating to an elevated
temperature, residual
2 0 water reacts with the isocyanate to liberate carbon dioxide, which is
drawn from the mixture by the
reduced pressure.
Alternatively, or in addition to the degassing procedure, the polyurethane
forming ingredients
may be diluted with solvents to reduce the viscosity of the polyurethane
forming mixture. Such
31
2193.52
solvents should be nonreactive and include tetrahydrofuran, acetone,
dimethylformamide,
dimethylacetamide, normal methylpyrrolidone, methyl ethyl ketone, etc. The
reduction in viscosity of
polyurethane forming ingredients aid their extrudability. For sealant
applications, however, the amount
of solvent should be kept as low as possible to avoid deteriorating their
adhesion to substrates. Other
solvents include xylene, ethyl acetate, toluene, and cellosolve acetate.
Plasticizers may also be included in the A- or B-side components to soften the
elastomer or
sealant and decrease its brittleness temperature. Examples of plasticizers
include the dialkyl phthalates,
dibutyl benzyl phthalate, tricresyl phosphate, dialkyl adipates, and
trioctylphosphate.
In addition to solvents or plasticizers, other ingredients such as adhesion
promoters, fillers, and
1 o pigments, such as clay, silica, fume silica, carbon black, talc,
phthalocyanine blue or green, titanium
oxide, magnesium carbonate, calcium carbonate, and UV-absorbers may be added
in amounts ranging
from 0 to 75 weight percent, based upon the weight of the polyurethane. Other
fillers include dissolved
gels, plasticells, graded and coated calcium carbonate, urea solids, the
reaction product of
hydrogenated castor oils with amines, and fibers.
The organic polyisocyanates are used to prepare the prepolymer, used in a one-
shot process, or
used for the further processing of hydroxyl terminated prepolymers. The
organic ~ polyisocyanates
include all essentially known aliphatic, cycloaliphatic, araliphatic and
preferably aromatic multivalent
isocyanates. Representative of these types are the diisocyanates such as m-
phenylene diisocyanate, 2,4-
toluene diisocyanate, 2,6-toluene diisocyanate, mixtures of 2,4- and 2,6-
toluene diisocyanate,
2 o hexamethylene diisocyanate, tetramethylene diisocyanate, cyclohexane-1,4-
diisocyanate,
hexahydrotoluene diisocyanate (and isomers), naphthalene-1,5-diisocyanate, 1-
methoxyphenyl-2,4-
diisocyanate, 4,4'-diphenylmethane diisocyanate, mixtures of 4,4'- and 2,4'-
diphenylmethane
' f
diisocyanate, 4,4'-biphenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenyl
diisocyanate, 3,3'-dimethyl-
32
a
_ ~ 2I9325~
4,4'-biphenyl diisocyanate and 3.3'-dimethyldiphenylmethane-4,4'-diisocyanate;
the triisocyanates such
as 4,4',4"-triphenylmethane triisocyanate, and toluene 2,4,6-triisocyanate;
and the tetraisocyanates such
as 4,4'-dimethyldiphenylmethane-2,2'-5,5'-tetraisocyanate and polymeric
polyisocyanates such as
polymethylene polyphenylene polyisocyanate, and mixtures thereof. Especially
useful due to their
availability and properties are 4,4'-diphenylmethane diisocyanate,
polymethylene polyphenylene
polyisocyanate, or mixtures thereof for rigid foams, or a mixture of the
foregoing with toluene
diisocyanates for semi-rigid foams.
Cn,ide polyisocyanates may also be used in the compositions of the present
invention, such as
crude toluene diisocyanate obtained by the phosgenation of a mixture of
toluenediamines or crude
1o diphenylmethane isocyanate obtained by the phosgenation of crude
diphenylmethane diamine. The
preferred or crude isocyanates are disclosed in U.S. Pat. No. 3,215,652.
In one embodiment of the invention, there is provided an isocyanate-terminated
prepolymer
suitable for the preparation of sealants and adhesives. This isocyanate-
terminated prepolymer may be
prepared by reacting the stoichiometric excess of organic isocyanate with a
mixture of a
polyoxyalkylene polyether triol and a polyoxyalkylene polyether diol. Either
one or both of the triol
and diol are the polyoxyalkylene polyether polymers described herein, that is,
containing an internal
block of vxypropylene groups and a second block of oxyalkylene groups derived
from a Ca or higher
alkylene oxide, preferably butylene oxides or a mixture of butylene oxide and
ethylene oxide. In a
preferred embodiment, it is the polyoxyalkylene polyether triol which is the
polyether polymer
2 0 described according to the invention. The equivalent ratio of NCO/OH
groups should be set at from
1.01/1 to about 10/1, more preferably from about 1.2/1 to about 2.5/1, to make
the ~isocyanate-
terminated prepolymers of this embodiment. Also, in this embodiment, the
equivalent weight of the
r
polyoxyalkylene polyether diol should range from about 250 to about 7000, and
that of the
33
,,
21932.~~.
polyoxyalkylene polyether triol ranging from 1300 or more, or preferably 1600
or more. Of course,
other isocyanate reactive compounds having functionalities greater than 3 can
be used in mixture with
the diols and triols in the manufacture of the isocyanate-terminated
prepolymer.
Once the isocyanate-terminated prepolymer is made, the sealant or the adhesive
may be
prepared by moisture curing the prepolymer if the free NCO content is low
enough, or by reacting the
prepolymer with firrther higher molecular weight polyoxyalkylene polyether
polyols or amine-
terminated polyoxyalkylene polyethers, .chain extenders, catalysts, fillers,
etc. For most specific
applications employing sealants, the isocyanate-terminated prepolymer is
moisture cured.
In another embodiment of the invention, there is provided a hydroxyl
terminated prepolymer
1 o suitable for the manufacture of sealants and adhesives. This embodiment, a
stoichiometric deficiency of
organic isocyanate is reacted with a polyoxyalkylene polyether polymer of the
invention, and optionally
other polyols or other isocyanate reactive compounds, at NCO-OH equivalent
ratios of 0.99:1 or less,
and even at 0.90:1 or less, or 0.85:1 or less. The hydroxyl terminated
prepolymer may then be mixed
with other B-side ingredients such as other polyols, chain extenders,
catalysts, surfactants, or fillers, for
reaction with further organic isocyanate to make a sealant or adhesive. The
purpose for making a
hydroxyl terminated prepolymer may be to adjust the viscosity of the B-side
components if a thicker
composition is desired for a given application. As in the above-described
embodiment, the B-side
components may comprise a mixture of triols and diols reacted with the sub-
stoichiometric amount of
organic isocyanate. Either one of or both of the diol or triol may be
manufactured according to the
2 o method described herein.
In yet a further embodiment of the invention, there is provided isocyanate'
terminated
prepolymers suitable for the manufacture of elastomers, and elastomers made
with the polyoxyalkylene
r
polyether polymers of the invention. Elastomers of the invention can be made
by the one-shot or the
34
- zss~z~z
prepolymer technique. In the prepolymer technique, there may be provided a
prepolymer having a free
NCO content of from 1 weight percent to 30 weight percent, usually from 1
weight percent to 10
weight percent. The prepolymer may be manufactured by reacting a
stoichiometric excess of organic
isocyanate with a polyoxyalkylene polyether diol, or a mixture of a polyether
diol and a polyether triol
having an average functionality of less than 2.3. One or both of the polyether
diol and triol are
manufactured according to the invention described herein. Preferably, a
polyoxyalkylene polyether diol
having an internal block of the oxypropylene groups and a second block of C4
or higher alkylene oxides
such as oxybutylene or a mixture of oxybutylene and oxyethylene groups is
reacted with a
stoichiometric excess of organic isocyanate at an NCO-OH equivalent ratio of
1.01:1 to 10:1. The
l0 polyoxyalkylene polyether diol is preferably terminated with oxyethylene
groups to increase its
reactivity with the organic isocyanate. The isocyanate terminated prepolymer
may then be reacted with
further B-side components such as polyether polyols, chain extenders,
catalysts, and other nonreactive
ingredients. Alternatively, the isocyanate terminated prepolymer may be
moisture cured in the
presence of a catalyst to accelerate the cure rate. The polyether diols used
in the manufacture of
elastomers have equivalent weights ranging from 250 to about 7000. When the
equivalent weight of
the polyether diol is about 1000 or more, the diol should be manufactured
according tb the process as
described herein to reduce terminal allylic unsaturation.
Shore A hardness of the sealants, adhesives, and elastomers made according to
the invention
can vary widely depending upon the ultimate application. Shore A hardness can
range from 0 to about
2 0 95. For most applications, however, Shore A hardness of sealants and
adhesives will range from 0 to
40, most typically from 0 to 20. In most elastomer applications, the Shore A
hardness will range from
to 95, with values of 50 to 90 being quite common. In some elastomeric
applications, the elastomer
r
will have a Shore D hardness of 55 to 75.
219322
The following examples illustrate some of the embodiments of the invention.
Preparation of Intermediate A
162.5 pounds of trimethylolpropane and 1.62 pounds of 90%KOH was charged, to a
clean dry
autoclave filled with nitrogen. After the charge, the agitator was started
slowly and advanced to 150
rpm, and the autoclave was heated to 65-70°C. The reactor was sealed,
purged three times with
nitrogen, and vented to about 0.25 bar. Subsequently, the contents were heated
to 125°C, vented to
0.15 bar, the 735.88 pounds of propylene oxide were added over about an 8 hour
period at less than
6.2 bar. The contents were further reacted for 3 hours, after which a vacuum
was applied and the
pressure reduced to lamb at 125°C. The vacuum was then relieved to
about 1 bar with nitrogen,
1 o cooled to about 90°C, and the contents transferred to a filter-
stripper tank.
Once the crude product has been transferred to the filter-stripper tank, 25
pounds of
MAGNESOL~ is added to the crude polyol, after which the filter-stripper tank
was sealed and purged
three (3) times at 3.5 bar with nitrogen. The final purge was vented to one
bar. The crude product
was treated in the filter-stripper tank at 90° to 95°C for one
(1) hour. Subsequently, the treated
product was recycled through the filter press until we attained haze-free
clarity and less than 20 ppm of
Na/K. The product was then transferred from the filter-stripper tank through
the filter press into a
flash-stripper tank. The polyol product was stripped of water at 105°C
and less than 13 mb for 60
minutes until the water content was less than 0.05 percent after vacuum
stripping. Subsequently, the
vacuum was relieved with nitrogen gas; and stabilizer was added to the
filtered, stripped product. The
2 0 intermediate product was subsequently cooled. This intermediate product is
designated as intermediate
A.
f
EXAMPLE 1- Polvol A
36
- ,2.93252
This Example describes the preparation of a low unsaturation block PO-[BO-EO
het]-EO
polyether triol using a conventional KOH catalyst.
552.9 grams (0.75 moles) of intermediate A and 30.6 grams (0.25 moles) of a
45,percent KOH
solution, were charged into a clean dry autoclave. The autoclave was sealed,
and the agitator started.
The autoclave was purged three (3) times with nitrogen and subsequently heated
to 105°C while
slowly evacuating to a pressure of less than l Omm Hg. The contents were batch
stripped for two (2)
hours. Subsequently, the vacuum was relieved to 0 psig with nitrogen; and the
autoclave was then
heated to 110°C. Propylene oxide was then added at 110°C at less
than 90 psig over a seven-hour
period. The contents were reacted for an additional four (4) hours at
110°C. Subsequently, the
reactor was evacuated to l Omm Hg and again heated to 125°C and
pressurized to 10 psig. A bomb of
mixed butylene oxide/ethylene oxide was charged to the autoclave at
125°C and less than 75 psig over
a two (2) hour period. The amount of butylene oxide and ethylene oxide added
was 706.5 grams (9.8
moles) and 464.3 grams (10.55 moles), respectively. The contents were reacted
for one more hour at
125°C, and subsequently the autoclave was evacuated at lOmm Hg. Once
evacuated, the autoclave
was again re-pressurized to 34 psig with nitrogen, and 242.2 grams of ethylene
oxide was charged into
the autoclave at less than 90 psig at 125°C over a one-hour period. The
contents v~rere reacted for
approximately one more hour at a constant pressure. Finally, the autoclave was
evacuated at lOmm
Hg for thirty minutes, the contents were cooled to 60°C, and then
discharged to a nitrogen-flushed
container.
2 o The polyether polyol was treated with 3 percent MAGNESOL~ and 1.5 percent
water at
95°C for one-and-a-half hours. The product was recycled through a
filter press until haze-free, and
. then stripped of water at 110°C and less than lOmm Hg for one (1)
hour. The treated product was
' r
then cooled to 60°C and stabilized with a common stabilizer package.
37
~1~~~~2
Chemical analysis of the polyether product revealed that the polyol had a
hydroxyl number of
27.5, and a degee of unsaturation of 0.055. The compatibility index was
6°C.
The structure of the final polyether polyol corresponded to a nucleus of a
trimethylolpropane
initiator molecule covalently bonded to a block of oxypropylene goups across
the hydroxyl
functionalities of the initiator molecule, and a block of mixed oxybutylene
and oxyethylene goups
attached to the block of oxypropylene goups, and terminated with a block of
oxyethylene groups.
Based on the weight of all alkylene oxide and initiator charges, the polyether
polymer had about 75
weight percent of oxypropylene groups, 20 weight percent of a block of
randomly mixed oxybutylene
goups and oxyethylene groups, and about 5 weight percent of a terminal block
of oxyethylene goups.
EXAMPLE 2
This example illustrates the manufacture of a low unsaturation PO-[BO-EO hetJ-
EO polyether
triol manufactured using cesium hydroxide as a catalyst.
The same procedure as employed in the manufacture of Polyol A in Example 1
above was used
to manufacture the polyol of this example, Polyol B, with the following noted
exceptions. The charges
of each ingedient were as follows:
588.9 gams of Intermediate Polyol A, 79.1 grams of a 50 percent cesium
hydroxide solution,
and 3610.7 gams of propylene oxide.
In the step of making the block of randomly mixed oxybutylene and oxyethylene
goups, the charges
were 699.9 gams of butylene oxide and 431.2 grams of ethylene oxide. In the
step for capping the
2 0 polyether polymer with oxyethylene goups, 268.8 gams of ethylene oxide
were added.
In the process for the manufacture of the polyether polymer polyol B, the
following
manufacturing steps differed as follows from Example 1:
r
38
_ 2~.~3~~2
Propylene oxide in this case was reacted for 4.5 hours at 110°C instead
of 4 hours. The mixed
oxides of butylene oxide and ethylene oxide were reacted for two (2) hours
instead of one ( 1 ) hour.
The resulting polyether polymer polyol B had a hydroxyl number of 27, a degree
of
unsaturation of 0.03, and a compatibility index of about 5°C. Based
upon the weight of the alkylene
oxide and initiator charges added, the polyether polymer contained about 75
weight percent of a block
of oxypropylene groups, 20 weight percent of a block of randomly mixed
oxyethylene groups and
oxybutylene groups, and about 5 weight percent of a terminal block of
oxyethylene groups.
EXAMPLE 3
This example illustrates the manufacture of sealants employing low
unsaturation PO-[BO-EO
1 o het]-EO polyether polymers made with a variety of catalysts.
Table I sets forth the results obtained from an evaluation of 14 different
polyether triols
employed in the preparation of sealants. Examples 1 and 12 through 14 are
comparison examples.
Each of the polyols 2 through 11 were prepared according to the procedures of
Examples 1 or 2.
Those polyether polymer triols using potassium hydroxide as a catalyst were
prepared in accordance
with Example 1, while those triols prepared with cesium hydroxide as a
catalyst were prepared in
accordance with Example 2. The charges of propylene oxide, butylene oxide, and
ethylene oxide were
adjusted to correspond with the stated weight percentage of oxypropylene
groups set forth in the table
below. Each of the triols 2 through 14 were terminated with a cap of 5 weight
percent of oxyethylene
groups. The amount of butylene oxide and ethylene oxide charged to form the
block of randomly
2 o distributed oxyethylene groups and oxybutylene groups was measured either
on a I :1 weight basis or a
1: I mole basis, as stated in the table.
The water test was conducted by immersing the sealant for thirty (30) days at
70°C in a bath of
water. The sealant was then removed from the water and its tensile properties
measured according to
39
2193252.
ASTM D412. A "Y" indicates the retention of greater than 50 percent of the
original tensile strength
of the sealanf prior to immersion in the water bath, while "N" indicates no
significant retention of
original tensile strength properties.
The polyols of comparative examples 12-14 were prepared using the listed
catalysts, and each
had average molecular weights of about 6200, with a terminal cap of
oxyethylene groups in an amount
of about 5 weight percent.
The following procedure was used to prepare the sealants. A prepolymer was
prepared by
reacting an organic isocyanate with a mixture of polyols. The mixture of
polyols was made up of 0.249
equivalents of Polyol C and 0.249 equivalents of each of Polyols 1-14 in
separate batches. Polyol C is
a propylene oxide adduct of propylene glycol having a hydroxyl number of about
56. Each of the
polyol blends were de-gassed, then dried under reduced pressure at 95°C
for two (2) hours and then
cooled to 40°C. Toluene diisocyanate, commercially available from BASF
Corporation as
LUPRANATE T80-1, was heated to 40°C in a reaction flask under a
constant nitrogen sparge. One of
the polyol blends was added to one (1) equivalent of the heated toluene
diisocyanate as quickly as
possible, keeping the resulting exothermic reaction at or below 60°C.
Once the polyol blend was fully
added, the mixture was heated to 80°C and kept at that temperature for
1.5 hours. , The free NCO
percent was then measured by titration. This procedure was repeated for each
polyol batch.
Each prepolymer was mixed with Polyol D at a ratio of 1:1 equivalents based on
the percent
NCO of the prepolymer, 25 weight percent of talc filler, 3 drops of silicone
surfactant DC-200, and 0.5
2 0 weight percent of dibutyltin dilaurate catalyst. Polyol D was a propylene
oxide adduct of propylene
glycol having an OH number of about 107. These ingredients were mixed, de-
gassed under reduced
pressure, and then poured into a 1/4" mold and cured at 70°C for four
hours. The resulting plaques
n f
2193252
were post-cured for two weeks at ambient temperature, 50 percent relative
humidity before testing.
The results of the evaluations are described in the table below.
The CI is a temperature at which the triol fell out of solution with water,
and 100 percent and
300 percent are the modulus measurements at 100 percent elongation and 300
percent elongation,
respectively, according to ASTM D412.
r
41
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The data generated from the evaluation of inventive examples 2-I 1
demonstrates a reduction in
the degree of unsaturation of each triol when compared with conventional
triols prepared with either
potassium hydroxide or cesium hydroxide as in examples 12 and 13. Thus, while
each triol had a
molecular weight of about 6200, those triols prepared with an internal block
of 25 to 80 percent
oxypropylene groups followed by a block of randomly distributed oxybutylene
and oxyethylene groups
and capped with ethylene oxide, had a degree of unsaturation much lower than
similar molecular
weight polyether polyols prepared with the same catalyst using only propylene
oxide and a cap of
ethylene oxide. When used in the manufacture of a sealant, the triol of
Example 12 prepared with
potassium hydroxide and all propylene oxide with an ethylene oxide cap was not
able to cure. In
to contrast, the triols prepared with potassium hydroxide catalyst and a
second block comprising at least
oxybutylene groups, capped with ethylene oxide, cured well and exhibited
improved tensile properties.
Not only did the inventive triols prepared with KOH have much lower degrees of
unsaturation than
the propylene oxide polyether polyol 12 prepared with KOH, but they also had
lower degees of
unsaturation than all propylene oxide polyether polyols made with cesium
hydroxide catalysts shown in
Example 13, and were on par with the tensile properties of the triols prepared
with double metal
cyanide catalysts. For the most part, the sealants prepared using the
inventive ~riols retained their
physical properties under the water immersion test. The inventive triols were
also sufficiently
hydrophobic as demonstrated by the low temperatures at which the triols fell
out of solution with
water. In contrast, the polyether polyol prepared with only butylene oxide and
ethylene oxide
2 0 according to comparative example I was too hydrophilic as shown by its
high CI value.
In sum, we dramatically reduced the degree of unsaturation of polyether
polyols suitable for the
r preparation of sealants and elastomers without employing an exotic and
expensive catalyst such as
DMC, while simultaneously improving the hydrophobicity and tensile strength
characteristics of the
43
2193252
polyether polyol and the resultant sealant. The polyether polyols of the
invention also advantageously
afford tremendously wide processing and formulating windows while retaining
improved degrees of
unsaturation and mechanical properties. For example, the ratio of butylene
oxide and ethylene oxide in
the block, as well as the overall amount of butylene oxide, can be widely
varied to obtain the desired
degree of hydrophobicity. The process is also not dependant upon removing
catalysts prior to addition
of an ethylene oxide cap as in the case of DMC catalysts. It could not be
foreseen that a high equivalent
weight polyether polyol using potassium hydroxide as a catalyst could be
manufactured with low
degrees of unsaturation or could be used to prepare a polyurethane sealant or
elastomer having
improved physical properties.
EXAMPLE 4
This example illustrates how the polyether diol having a low degree of
unsaturation was made.
Diols are frequently used in the manufacture of elastomers. To enhance their
reactivity, diols
frequently have a high weight percent of an oxyethylene cap. Accordingly, this
example illustrates how
a polyether diol having a low degree of unsaturation and high equivalent
weight was made.
An intermediate B was manufactured by charging 1397.7 grams of diproliylene
glycol and
732.5 grams of a 50% solution of cesium hydroxide catalyst to a clean dry
autoclave. The autoclave
was sealed, agitation initiated, and purged three times with nitrogen. The
autoclave was heated to
about 105°C and evacuated at less than 10 mm Hg to strip water for
about one hour. The vacuum was
2 0 relieved to 0 psig with nitrogen, after which 3102.3 grams of propylene
oxide was added at 105°C, less
than 90 psig, and over a four and one-half hour period. After addition of
propylerie oxide was
completed, the reaction proceeded for another hour at the same temperature.
The autoclave was then
r
44
r
__ 21932~~.
evacuated, the volatiles stripped, and the reaction mixture cooled to
60°C. The contents were
discharged to a nitrogen flush container.
781.6 gams of intermediate B were added to a separate, dry, clean autoclave. ,
The autoclave
was sealed, agitation initiated, and the autoclave was purged three times with
nitrogen. The autoclave
was then heated to about 105°C, and slowly evacuated to strip
volatiles. Once stripped, the vacuum
was relieved with nitrogen after which 2510.7 grams of propylene oxide were
added over a five hour
period, keeping the pressure to less than 90 psig. Once the addition was
complete, the reaction
continued for another three hour period. Subsequently, the autoclave was
evacuated to collect any
unreacted propylene oxide volatiles, after which it was re-pressurized to 0
psig with nitrogen. The
reactor was then heated to about 125°C. A mixture of 670.7 grams of
butylene oxide and 409.3 grams
of ethylene oxide were simultaneously added to the autoclave at 125°C
over a two and one-half hour
period at less than 75 psig. The reaction continued for about four and one-
half hours, after which it
was evacuated to collect any remaining volatiles. Once the autoclave was re-
pressurized, about 1080.0
grams of ethylene oxide were be added at 125°C over a two hour period
and at less than 90 psig. The
ethylene oxide was reacted to a constant pressure over a one hour period,
after which the autoclave
was evacuated for about a half an hour to collect any volatiles. The contents
in the reaction in the
autoclave were cooled to 60°C and discharged to a nitrogen flushed
container.
The resulting polyether polyol was treated with a 3% Magnasol~ absorber and a
1.5% water
at about 95°C for one and one-half hours, recycled through a filter
press, stt;pped, and stabilized with
2 0 conventional stabilizers.
The resulting polyether polyol was subjected to analysis which showed that the
polyether
r polymer was made of an internal block of 60 weight percent oxypropylene
groups, a 20 weight percent
block of randomly distributed oxybutylene and oxyethylene groups in a 1 to 1
molar ratio, and a 20
21932~z
vi~eight percent terminal block of oxyethylene goups. The resulting polyether
polymer had an
equivalent weight of about 1500, an OH number of about 37.3, and a
compatibility index of greater
than 70°C. Remarkably, the level of unsaturation was only 0.014.
EXAMPLE 5
This example will demonstrate the level of unsaturation for about a 2000
equivalent weight
polyether diol suitable for the manufacture of elastomers, employing cesium
hydroxide as a catalyst.
The same procedure as used in example 4 above was employed here. The only
difference in
charges were 590.8 gams of intermediate B, and 2688.9 gams of propylene oxide.
The resulting
polyether polymer diol had an internal block of 60 weight percent oxybutylene
groups, a 20 weight
percent block of randomly distributed oxybutylene and oxyethylene groups in a
1 to 1 molar ratio, and
a 20 weight percent terminal block of oxyethylene goups. Analysis showed that
the polyether diol had
an OH number of about 28.6, which corresponds to a calculated equivalent
weight of about 1960, and
a compatibility index of Beater than 70°C. Remarkably, the level of
unsaturation for this high
equivalent weights polyether diol was only 0.019.
EXAMPLE 6
In examples 6-7, several 1500 equivalent weight polyether polyols were
manufactured using
different catalysts and having different stn~ctures.
An intermediate C was manufactured by charging 847.8 gams of dipropylene
glycol and 102.5
gams of a 50% solution of cesium hydroxide catalyst to a clean dry autoclave.
The autoclave was
2 o sealed, agitation initiated, and purged three times with nitrogen. The
autoclave was heated to about
105°C and evacuated at less than 10 mm Hg to strip water for about one
hour. The vacuum was
relieved to 0 psig with nitrogen, after which 1902.7 gams of propylene oxide
were added at 105°C at
less than 90 psig and over a four hour period. After the addition of propylene
oxide was completed,
46
2~.932~~
the reaction was continued for another hour at the same temperature. The
autoclave was then
evacuated, the volatiles stripped for 30 minutes, and the vacuum relieved with
nitrogen. The contents
were discharged to a nitrogen flush container. The OH number was about 251.6,
the gardner color
was about 1, and the wt.% of cesium hydroxide was about 1.8.
In a separate dry clean autoclave, 747.7 grams of intermediate C and 71.0 gams
of a 50%
cesium hydroxide solution. were added. The same procedure as in Example 4 was
employed, except
that the amount of propylene oxide added was 2517.2 g, the amount of ethylene
oxide added as the
heteric block was 540g, the amount of butylene oxide added was 540g, and the
amount of ethylene
oxide added as the terminal cap was 1080.0g.
1o The resulting polyether polyol 6 was subjected to analysis which showed
that the polyether
polymer was made of an internal block of 60 weight percent oxypropy(ene
groups, a 20 weight percent
block of randomly distributed oxybutylene and oxyethylene groups in a 1 to 1
weight ratio, and a 20
weight percent terminal block of oxyethylene groups. The resulting polyether
polymer had an
equivalent weight of about 1500, an OH number of about 37, and a compatibility
index of greater than
70°C. Remarkably, the level of unsaturation was only 0.014.
EXAMPLE 7
This polyether polyol was prepared with a standard KOH catalyst as a low
unsaturation 1500
equivalent weight polyol.
Intermediate D was prepared by adding about 35 moles of propylene glycol to a
dry, nitrogen
2 0 filled reactor, and heated to 120F. A 45% solution of KOH was added, mixed
at less than 140F and 50
psig. Upon addition of about 294 moles of propylene oxide to the reactor, the
heat was increased to
257F and held during the reaction. Upon completion of the reaction, the
contents were cooled to 1 SOF
r
and discharged to storage.
47
'~
700.3 grams of Intermediate D was charged along with 18 grams of KOH into a
clean dry
autoclave, sealed, and agitated. After purging, the autoclave was heated to
lOSC and depressurized to
less than lOmmHg for stripping off water. The same procedure was used for the
remainder of the
reaction as empolyed in Example 4 with the following further modifications:
2686.2 g of propylene
oxide were added over a 6 hour period and reacted for 3 more hours, after
which the autoclave was
evacuated for 30 minutes instead of 10 minutes; the mixed oxides of ethylene
and butylene were added
at a 1:1 weight ration of 560:560 grams over a 1.5 hour period and reacted for
3 more hours after
which the autoclave was depressurized for 10 minutes; and 1120 g of ehtylene
oxide were added as a
cap over a 1.5 hour period and reacted for 1 more hour. The polyol was
stabilized by the same
procedure.
The resulting polyether polyol had an OH number of 37, an acid number of
0.004, a level of
unsaturation of 0.02, and a CI of greater than 70C in a 50/50 isopropyl/water
ratio. The polyether
polymer was 1500 equivalent weight difunctional polyol with a 60 wt.%
polyoxypropylene internal
block, a 20 wt.% block of randomly mixed polyoxyethylene and polyoxybutylene
groups, and a 20
wt.% cap of polyoxyethylene grpups.
r
48
