U.S. patent number RE38,415 [Application Number 10/267,119] was granted by the patent office on 2004-02-03 for use of n-(aminoalkyl) pyrrolidines as catalysts for the polyisocyanate polyaddition process.
This patent grant is currently assigned to Bayer Aktiengesellschaft. Invention is credited to Uwe Scholz, Richard Weider.
United States Patent |
RE38,415 |
Weider , et al. |
February 3, 2004 |
Use of N-(aminoalkyl) pyrrolidines as catalysts for the
polyisocyanate polyaddition process
Abstract
The present invention relates to a process for preparing
polyisocyanate polyaddition products by reacting (a)
polyisocyanates with (b) relatively high molecular weight compounds
containing at least two isocyanate-reactive hydrogen atoms and (c)
chain-extending agents, in the presence of (d)
N-(aminoalkyl)pyrrolidine catalysts corresponding to formula (I)
##STR1## in which R is a C.sub.2-12 alkylene group (optionally
containing O or N atoms but not isocyanate-reactive groups) and R'
is hydrogen or a C.sub.1-4 alkyl group, (e) optionally, other known
catalysts, and (f) other known additives.
Inventors: |
Weider; Richard (Leverkusen,
DE), Scholz; Uwe (Cologne, DE) |
Assignee: |
Bayer Aktiengesellschaft
(Leverkusen, DE)
|
Family
ID: |
30448779 |
Appl.
No.: |
10/267,119 |
Filed: |
October 7, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
817240 |
Jan 6, 1992 |
05134217 |
Jul 28, 1992 |
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Foreign Application Priority Data
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Jan 12, 1991 [DE] |
|
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4100811 |
|
Current U.S.
Class: |
528/53; 521/129;
528/129 |
Current CPC
Class: |
C08G
18/2018 (20130101); C08G 2110/0083 (20210101); C08G
2110/0008 (20210101); C08G 2290/00 (20130101) |
Current International
Class: |
C08G
18/00 (20060101); C08G 18/20 (20060101); C08G
018/08 (); C08G 018/18 (); C08J 009/00 () |
Field of
Search: |
;528/53,129 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Foelak; Morton
Attorney, Agent or Firm: Gil; Joseph C. Whalen; Lyndanne M.
Brown; N. Denise
Claims
What is claimed is:
1. A process for preparing a polyisocyanate polyaddition product
comprising reacting (a) a polyisocyanate with (b) a relatively high
molecular weight compound containing at least two
isocyanate-reactive hydrogen atoms and (c) a chain-extending agent,
in the presence of (d) an N-(aminoalkyl)pyrrolidine catalyst
corresponding to the formula ##STR5## in which R is a C.sub.2-12
alkylene group (optionally containing O or N atoms but not
isocyanate-reactive groups) and R' is .[.hydrogen or.]. a C.sub.1-4
alkyl group, (e) optionally, other known catalysts, and (f) other
known additives.
2. A process according to claim 1 wherein R is a 1,3-propylene
group and R' is .[.hydrogen or.]. C.sub.1-4 alkyl group.
3. A process according to claim 1 wherein the
N-(aminoalkyl)pyrrolidine catalyst is N-(3-aminopropyl)pyrrolidine
and N-(3-(methylamino)propyl)pyrrolidine.
4. A process according to claim 1 wherein the polyisocyanate
polyaddition product is a cellular plastic.
Description
BACKGROUND OF THE INVENTION
This invention relates to the use of N-(aminoalkyl)pyrrolidines as
catalysts for the preparation of products by the polyisocyanate
addition process. These catalysts may be used as a replacement for
or in combination with known urethane catalysts, such as
1,4-diazabicyclo[2.2.2]octane (DABCO), for the preparation of rigid
or flexible polyurethane foams and other polyurethane products. In
the context of the present invention, the term "polyurethane
products" is intended to encompass all reaction products of
polyisocyanates with compounds containing at least two
isocyanate-reactive hydrogen atoms. That is, the term
"polyurethane" is understood to encompass, for example, pure
polyurethanes, polyurethane polyureas, or pure polyureas.
The rate of the reaction between isocyanate groups and compounds
containing NCO-reactive hydrogen atoms is determined not only by
the temperature of the starting products and their structure but
particularly by the use of suitable catalysts. In practice, bases
(for example, tertiary amines such as triethylamine) are used
mainly as nucleophilic catalysts, whereas organometallic compounds
(for example, tin carboxylates such as tin(II) octoate) are used
mainly as electrophilic catalysts. The prior art processes are
based on the joint use of Lewis acids and Lewis bases, which is
normally characterized by synergistic effects. However, it is also
known that amines are exclusively used as catalysts in a number of
applications. However, only a few of the large number of known
amine catalysts (cf. Ullmann, 4th Edition, and Kunststoffhandbuch,
Vol. VII, Polyurethane, Hanser-Verlag, Munich (1983)) have hitherto
been adopted for use on a wide scale, with
1,4-diazabicyclo[2.2.2]octane (DABCO), bis(2-dimethylaminoethyl)
ether, triethylamine, dimethyl cyclohexylamine,
dimethylethanolamine, dimethylbenzylamine, methylmorpholine, and
ethylmorpholine being the most important. More particularly, of
course, catalysts distinguished by high activity, economic
production, and a broad range of applications are used. Another
increasingly important consideration is the toxicological
evaluation of the catalysts with regard to processing safety and
odor emission. Many of the amine catalysts in use today, such as
DABCO or triethylamine, may be regarded as unsatisfactory in this
respect because of their high volatility and the relatively
intensive amine odor that is carried over into the end product
produced with such catalysts.
Amine catalysts containing an additional, isocyanate reactive group
corresponding to the general formula ##STR2##
are described in German Offenlegungsschrift 2,116,535, which also
mentions, inter alia, compounds in which the two substituents R are
attached to each other to form 3- to 6-membered rings. The use of
one representative member of this special class of compounds,
namely N-(2-aminoethyl)aziridine, is illustrated by Examples 10 and
16-18 of the German patent. In the Examples mentioned, this
compound proved to be distinctly poorer than the corresponding
acyclic compounds with regard to the density, strength, and
elasticity of the foams prepared (Example 10) and particularly with
regard to activity (Examples 16 to 18).
It has now surprisingly been found that certain pyrrolidine
derivatives may be used advantageously as catalysts for the
preparation of polyurethanes. Compared with the above-mentioned
N-(2-aminoethyl)aziridine and cyclic compounds other than those
having 5-membered rings, the compounds used in accordance with the
invention have considerably greater activity that even surpasses
that of the acyclic members disclosed in the above-cited German
patent specification. Another advantage is the faint odor and low
volatility of compounds in which the isocyanate-reactive groups are
bound in the polymer, which leads to distinctly reduced odor
emission in the preparation of polyurethane products. In addition,
other advantages have been observed, including, for example, ease
of handling (because the pyrrolidines preferably used are liquid),
good curing behavior, and, not least, the very simple preparation
of the compounds.
SUMMARY OF THE INVENTION
According to the present invention relates to a process for
preparing polyisocyanate polyaddition products comprising reacting
(a) polyisocyanates with (b) relatively high molecular weight
compounds containing at least two isocyanate-reactive hydrogen
atoms and (c) chain-extending agents, in the presence of (d)
N-(aminoalkyl)pyrrolidine catalysts corresponding to formula (1)
##STR3## in which R is a C.sub.2-12 alkylene group (optionally
containing O or N atoms but not isocyanate-reactive groups) and R'
is hydrogen or a C.sub.1-4 alkyl group, (e) optionally, other known
catalysts, and (f) other known additives.
DETAILED DESCRIPTION OF THE INVENTION
The polyisocyanate reaction products prepared according to the
present invention are preferably cellular plastics.
The catalysts used according to the invention are known compounds.
The preferred catalysts are prepared, for example, by addition of
pyrrolidine onto acrylonitrile, followed by reduction and,
optionally, subsequent alkylation by known methods. The catalysts
according to the invention are colorless to pale yellowish
compounds, the preferred types being liquid, and are soluble in
organic solvents and soluble or dispersible in water. The quantity
of the catalysts is generally from about 0.01 to about 5% by
weight, based on the isocyanate-reactive compound. Although more
than the above-mentioned quantity may be used, no advantage is
gained.
Preferred compounds are catalysts corresponding to general formula
(I) in which R is a 1,3-propylene group and R' is hydrogen or
C.sub.1-4 alkyl. Suitable catalysts according to the invention
include, for example, N-(2-aminoethyl)pyrrolidine,
N-(2-(methylamino)ethyl)pyrrolidine, N-(3-aminopropyl)-pyrrolidine,
N-(3-methylamino)propyl)pyrrolidine,
N-(3-(ethylamino)propyl)pyrrolidine,
N-(3-(propylamino)propyl)pyrrolidine, N-(4-aminobutyl)pyrrolidine,
N-(3-amino-2-methylpropyl)-pyrrolidine, and
N-(3-methylamino-2-methylpropyl)pyrrolidine. Preferred catalysts
include N-(3-aminopropyl)pyrrolidine,
N-(3-methylamino)propyl)prrolidine,
N-(3-(ethylamino)propyl)-pyrrolidine, and
N-(3-(propylamino)propyl)pyrrolidine, with
N-(3-aminopropyl)pyrrolidine and
N-(3-(methylamino)propyl)-pyrrolidine being particularly
preferred.
The isocyanate-reactive compounds which are used as component (b)
in the process accordin9 to the invention are those used in
previously known processes for the preparation of polyurethanes and
are described, for example, in Kunststoffhandbuch, Vol. VII,
Polyurethane, Hansen-Verlag, Munich (1963) or in Houben-Weyl,
Makromolekulare Stoffe Vol. E 20. The isocyanate reactive compounds
have a molecular weight M.sub.n of 3000-10000, preferably
3000-6000, e.g. polyether-polyols such as Bayfit.RTM.3973 or
Bayfit.RTM.3963 (commercial product Bayer AG).
The compounds containing NCO groups used as component (a) in the
process of the invention are the same compounds used in previously
known processes and are described, for example, in
Kunststoffhandbuch, Vol. VII, Polyurethane, Hansen-Verlag, Munich
(1983) or in Houben-Weyl, Makromolekulare Stoffe, Vol. E20.
When carrying out the process according to the invention, the
substituted pyrrolidines are used in the same way as the previously
known catalysts. For example, the catalyst may be used in its
liquid form or may be dissolved in a polyol or a suitable solvent.
The catalyst may be used at any temperature - or under other
conditions - either alone or in combination with other known
catalysts that are suitable for the preparation of polyurethanes.
Suitable other catalysts include organic or inorganic tin compounds
or other organometallic compounds; tertiary amines, alkanolamines,
cyclic amines, polyamines, and the like; alkali metal compounds;
and other co-catalysts.
The catalysts according to the invention are preferably used in a
quantity of at least 50% by weight, based on the total quantity of
catalyst used.
The process according to the invention is suitable for conventional
production methods, including, for example, one-shot or prepolymer
processes for the preparation of polyurethane foams, polyurethane
elastomers, polyurethane coatings, and the like, and for the
crosslinking reaction which is often desirable after the direct
polyaddition.
All other conditions are the same as those used in conventional
urethane polyaddition processes. In each case, other known
additives may be used, including chain-extending agents, blowing
agents, foam stabilizers, emulsifiers, dyes, pigments, and
fillers.
The above-mentioned catalysts of the invention accelerate the
polyaddition reaction to a considerable extent so that the quantity
of catalyst required is very small. Because the catalyst compounds
according to the invention have only a faint odor and because they
represent substantially nonvolatile liquids and incorporable
compounds, the polyurethane products obtained are free from
unwanted odors.
The following examples further illustrate details for the process
of this invention. The invention, which is set forth in the
foregoing disclosure, is not to be limited either in spirit or
scope by these examples. Those skilled in the art will readily
understand that known variations of the conditions of the following
procedures can be used. Unless otherwise noted, all temperatures
are degrees Celsius and all parts and percentages are parts by
weight and percentages by weight, respectively.
EXAMPLES
Examples 1 to 6
These Examples demonstrate the high catalytic activity of
N-(3-aminopropyl)pyrrolidine and
N-(3-methylamino)propyl)pyrrolidine in comparison with analogous
catalysts which do not contain a pyrrolidine ring in a polyurethane
cold-cure flexible foam system.
The following catalysts were used: Catalyst 1:
N-(3-aminopropyl)piperidine Catalyst 2:
N-(3-aminopropyl)-N'-methylpiperazine Catalyst 3:
3-dimethylaminopropylamine Catalyst 4: N-(3-aminopropyl)pyrrolidine
Catalyst 5: N-(3-(methylamino)propyl)pyrrolidine
The catalysts have the following formulas: ##STR4##
Catalysts 4 and 5 correspond to the invention, with the other
catalysts being comparison catalysts.
Component A: 37.10 parts mixture of 80% 2,4-toluene diisocyanate
and 2,6-toluene diisocyanate (in a ratio of 80:20) and 20%
4,4'-diisocyanatodiphenylmethane with polymeric components (NCO
content 44.5 .+-. 0.5% by weight) (Desmodur .RTM. VT 06, a
commercial product of Bayer AG) Component B: 100.00 parts polyether
polyol (OH value 28 .+-. 2 mg KOH/g) prepared by reaction of
trimethylolpropane (TMP) with propylene oxide (PO) and sub- sequent
reaction with ethylene oxide (EO) in a PO:EO ratio of 82:18 3.00
parts water 0.05 part 70% solution of bis(2-dimethylaminoethyl)
ether in dipropylene glycol (DPG) 0.25 part 33% solution of
diazabicyclo[2.2.2]octane (DABCO) in DPG 0.20 part foam stabilizer
B4617 (Goldschmidt AG) 0.80 part polyether polysiloxane as
stabilizer (Stabilisator IS 50, a product of Bayer AG) 0.6 part
catalyst 1 to 5
Component A is combined with component B and the mixture is
thoroughly mixed for 6 seconds using a high-speed stirrer. The
reaction mixture is then foamed in an open mold at room
temperature.
The results obtained with the various catalysts are set out in
Table 1.
TABLE I Cream time Gel time Rise time Example Catalyst (sec) (sec)
(sec) 1 None 9 108 213 2 1 9 105 210 3 2 8 75 150 4 3 7 52 115 5* 4
6-7 48 100 6* 5 4-5 46 93 *Examples according to the invention
Foams having a satisfactory foam structure were obtained.
* * * * *