U.S. patent application number 09/068361 was filed with the patent office on 2001-06-28 for method of producing organic diurethanes and/or polyurethanes and their use in the production of di-and/or polyisocyanates.
Invention is credited to LAQUA, GERHARD, OTTERBACH, ANDREAS, SCHONER, ULRICH, SCHWARZ, HANS VOLKMAR.
Application Number | 20010005761 09/068361 |
Document ID | / |
Family ID | 7776781 |
Filed Date | 2001-06-28 |
United States Patent
Application |
20010005761 |
Kind Code |
A1 |
LAQUA, GERHARD ; et
al. |
June 28, 2001 |
METHOD OF PRODUCING ORGANIC DIURETHANES AND/OR POLYURETHANES AND
THEIR USE IN THE PRODUCTION OF DI-AND/OR POLYISOCYANATES
Abstract
Organic diurethanes and/or polyurethanes are prepared by
reacting organic diamines and/or polyamines (a) with urea and/or
alkyl cabamates (b) and alcohols (c) in the presence of soluble
zirconium compounds, preferably zirconium alkoxides, zirconium
acetate or zirconium acetylacetonate, as catalyst (d). They can be
used for preparing diisocyanates and/or polyisocyanates by thermal
dissociation.
Inventors: |
LAQUA, GERHARD;
(LIMBURGERHOF, DE) ; SCHONER, ULRICH;
(SCHWARZHEIDE, DE) ; OTTERBACH, ANDREAS;
(FRANKENTHAL, DE) ; SCHWARZ, HANS VOLKMAR;
(WATERLOO, BE) |
Correspondence
Address: |
BASF CORPORATION
PATENT DEPARTMENT
1419 BIDDLE AVENUE
WYANDOTTE
MI
481923736
|
Family ID: |
7776781 |
Appl. No.: |
09/068361 |
Filed: |
May 7, 1998 |
PCT Filed: |
October 30, 1996 |
PCT NO: |
PCT/EP96/04710 |
Current U.S.
Class: |
560/115 ;
560/118; 560/157; 560/315 |
Current CPC
Class: |
C07C 269/04
20130101 |
Class at
Publication: |
560/115 ;
560/315; 560/157; 560/118 |
International
Class: |
C07C 269/00; C07C
069/74; C07C 261/00; C07C 271/00; C07C 259/00; C07C 239/00; C07C
381/00; C07C 331/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 7, 1995 |
DE |
19541384.9 |
Claims
We claim:
1. A process for preparing aliphatic and/or cycloaliphatic organic
diurethanes and/or polyurethanes by reacting a) aliphatic and/or
cycloaliphatic organic di- and/or polyamines with b) urea, alkyl
carbamates or mixtures of urea, alkyl carbamates and/or dialkyl
carbonates c) alcohol in the presence of a d) catalyst, wherein the
catalyst used comprises zirconium compounds soluble in the reaction
mixture.
2. A process as claimed in claim 1, wherein the soluble zirconium
compounds used are zirconium-n-butoxide, zirconium acetate or
zirconium acetylacetonate.
3. A process as claimed in claim 1 or 2, wherein the soluble
zirconium compounds are used in an amount of 0.00001 to 1 mol %,
based on the diamines and/or polyamines.
4. A process as claimed in any of claims 1 to 3, wherein the
organic diamines used are 1,6-hexanediamine or
3-aminomethyl-3,5,5-trimethylcyclo- hexylamine.
5. A process as claimed in any of claims 1 to 4, wherein the
diamines and/or polyamines (a), urea (b) and alcohols (c) are
reacted in such amounts that the ratio of NH.sub.2 groups of the
diamines and/or polyamines (a) to urea (b) to hydroxyl groups of
the alcohols (c) is 1:0.7-5:1-50.
6. A process as claimed in any of claims 1 to 5, wherein the
reaction is carried out at from 160.degree. C. to 300.degree. C.
and a pressure of from 0.1 to 60 bar.
7. A process as claimed in any of claims 1 to 6, wherein the
reaction is carried out in the presence of polyurets, substituted
ureas, substituted and unsubstituted polyureas,
oligourea-polyurethanes, high-boiling oligomers and other
by-products formed in the thermal dissociation of the diurethanes
and/or polyurethanes to give diisocyanates and/or polyisocyanates.
Description
[0001] The present invention relates to a process for preparing
organic diurethanes and/or polyurethanes, preferably aliphatic or
cycloaliphatic diurethanes, by reacting the corresponding organic
diamines and/or polyamines (a) with urea and/or alkyl carbamates
(b) und alcohols (c) in the presence of soluble zirconium compounds
such as zirconium alkoxides, zirconium acetate or zirconium
acetylacetonate, as catalyst (d).
[0002] The present invention also relates to the use of diurethanes
and/or polyurethanes prepared by the process of the present
invention for preparing organic diisocyanates and/or
polyisocyanates by thermal dissociation.
[0003] Organic polyisocyanates, such as aromatic, aliphatic or
cycloaliphatic polyisocyanates, are valuable starting materials for
producing polyisocyanate polyaddition products, for example
polyurethane (PU) foams, surface coatings, dispersions, adhesives,
polyisocyanurate (PIR) foams, thermoplastistic PU elastomers (TPU)
und compact or cellular PU- or PU-polyurea elastomers.
[0004] The industrial processes for preparing organic
polyisocyanates are based on reaction of the corresponding organic
polyamines with phosgene to give polycarbamic chlorides and thermal
dissociation of the latter to give the polyisocyanates and hydrogen
chloride and the thermal dissociation of monomeric diurethanes
and/or polyurethanes into diisocyanates and/or polyisocyanates and
alcohol.
[0005] Problems in the process using phosgene are, in particular,
the high conversion of chlorine via phosgene and carbamic chloride
into hydrogen chloride, the toxicity of the phosgene and the
corrosiveness of the reaction mixture, the lability of the solvents
generally used and the formation of halogen-containing
residues.
[0006] There have therefore been many attempts to prepare organic
isocyanates, preferably aromatic and (cyclo)aliphatic diisocyanates
and/or higher-functional polyisocyanates, by a phosgene-free
process.
[0007] According to EP-A-28 338 (U.S. Pat. No. 4,290,970) aromatic
diisocyanates and/or polyisocyanates are prepared by a two-stage
process in which, in the first reaction stage, primary aromatic
diamines and/or polyamines are reacted with alkyl carbamates in the
absence or presence of catalysts and the absence or presence of
urea and alcohol to give aryl diurethanes and/or polyurethanes and
the ammonia thus formed is, if desired, separated off, and the aryl
diurethanes and/or polyurethanes obtained are converted in the
second reaction stage into aromatic diisocyanates and/or
polyisocyanates by thermal dissociation
[0008] Continuous, multistage processes for the phosgene-free
preparation of organic polyisocyanates are likewise known.
[0009] EP-A-0 355 443 (U.S. Pat. No. 5,087,739) relates to a
circulation process for preparing (cyclo)aliphatic diisocyanates by
conversion of the corresponding diamines into diurethanes and
thermal dissociation of the latter, which reduces decreases in
yield by the reaction mixture from the urethane dissociation stage
being recirculated to the urethane formation stage after reaction
with alcohol. By-products which cannot be recirculated are removed
by distillative fractionation of the reaction mixture from the
urethane formation stage; in this fractionation the unusable
residue is obtained as bottom product and all lower-boiling
components, including the diurethane, are taken off at the top.
[0010] EP-A-0 568 782 (U.S. Pat. No. 5,360,931) describes a
multistage process for the continuous phosgene-free preparation of
(cyclo)aliphatic diisocyanates, comprising the conversion of
(cyclo)aliphatic diamines in a distillation reactor into the
corresponding (cyclo)alkylenebisureas, their reaction with alcohol
in a pressure distillation reactor to give the (cyclo)alkylene
biscarbamates and the thermal dissociation of the latter in a
combined dissociaton and rectification column to give the
(cyclo)alkylene diisocyanates and alcohol in a liquid phase without
use of solvents.
[0011] According to EP-A-0 566 925 (U.S. Pat. No. 5,386,053), a
multistage process for preparing organic polyisocyanates comprises
converting the organic polyamines into monomeric polyurethanes
using carbonic acid derivatives and alcohols and thermally
dissociating the monomeric polyurethanes. In certain reaction
stages of this process, the polyisocyanates prepared and unusable
residues are separated off and the reusable by-products are
recirculated to earlier stages.
[0012] The economics of the continuous phosgene-free processes for
preparing organic polyisocyanates is decisively influenced by the
purity of the organic monomeric diurethanes and/or higher
polyurethanes used for the thermal dissociation and the undesired
secondary reactions, partly resulting from impurities and
by-products, and the tendency of the reaction mixture to form
deposits, of resinous material and blockages in reactors and
work-up apparatus.
[0013] Organic monomeric diurethanes and/or higher polyurethanes
can be prepared by reacting organic polyamines with carbonic acid
derivatives, preferably urea and/or alkyl carbamates, and alcohols
in the absence or presence of catalysts.
[0014] According to EP-B-0 018 586 (U.S. Pat. No. 4,713,476 and
U.S. Pat. No. 4,851,565) aliphatic and/or cycloaliphatic
diurethanes and/or polyurethanes can be prepared by reacting the
corresponding polyamines with urea and alcohols in the presence of
catalysts. In a similar manner, according to EP-B-0 019 109 (U.S.
Pat. No. 4,611,079), aromatic diurethanes and/or polyurethanes can
be obtained using aromatic polyamines. Suitable catalysts mentioned
are inorganic or organic compounds containing one or more cations
of metals of groups IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA, VB,
VIB, VIIB and VIIIB of the Periodic Table, eg. halides, sulfates,
phosphates, nitrates, borates, alkoxides, phenoxides, sulfonates,
oxides, hydrated oxides, hydroxides, carboxylates, chelates,
carbonates and thio- or dithiocarbamates. Aryl mono-, di- and/or
polyurethanes can, according to EP-B-0 018 538 (U.S. Pat. No.
4,278,805 and U.S. Pat. No. 4,375,000), be prepared by reacting
corresponding primary aromatic monoamines or polyamines with alkyl
carbamates in the presence of the abovementioned catalysts.
[0015] N,O-disubstituted urethanes can, according to EP-A-0 028 331
(U.S. Pat. No. 4,480,110), be prepared by reacting mixtures of
substituted ureas and N-unsubstituted urethanes and/or urea and/or
polyurets with alcohols in the presence of esterification catalysts
for carboxylic acids. According to EP-B-0 027 940 (CA-A-1 144 562),
urethanes can be prepared by reacting urea or polyurets with
primary amines and alcohols in the presence of compounds which
exercise a catalytic influence on the esterification reaction of
carboxylic acids with alcohols and which also have an accelerating
action on the urethane reaction. Suitable catalysts mentioned are:
inorganic and organic bases which are inert under the reaction
conditions, Lewis acids and salts or complexes, in particular
chelates of transition metals. Among numerous catalysts which can
be used, mention is also made, by way of example, of coordination
compounds of iron, nickel, cobalt, zinc, manganese, molybdenum,
titanium, zirconium, thorium, hafnium and vanadium with
.beta.-diketones, eg. acetylacetone and .beta.-ketoesters. The best
catalytic activity was shown by zinc octoate with a conversion of
97 mol %, while iron acetylacetonate with 90 mol % gave a
comparatively low catalytic effect, particularly for
industrial-scale processes.
[0016] To ensure sufficient quality of the organic diurethanes
and/or higher polyurethanes for a thermal dissociation to give
organic polyisocyanates, it is desirable to have preparative
processes for polyurethanes which ensure both a high space-time
yield and a high selectivity, eg. of .gtoreq.98 mol % of
polyurethane, based on the organic polyamine used.
[0017] Partially reacted intermediates containing urea groups cause
considerable interference in the urethane dissociation to give the
polyisocyanate and can be separated from the polyurethane formed
only with difficulty.
[0018] It is an object of the present invention to prepare
diurethanes and/or higher polyurethanes in very high space-time
yields with high selectivities in order to inexpensively convert
these into polyisocyanates by thermal dissociation under optimum
reaction conditions.
[0019] We have found that this object is achieved by a special
urethane catalysis.
[0020] The present invention accordingly provides a process for
preparing organic diurethanes and/or higher polyurethanes,
preferably aliphatic or cycloaliphatic diurethanes and/or higher
polyurethanes, in particular aliphatic or cycloaliphatic
diurethanes, by reacting
[0021] a) organic diamines and/or polyamines, preferably aliphatic
or cycloaliphatic diamines, with
[0022] b) urea and/or alkyl carbamates and
[0023] c) alcohols in the presence of a
[0024] d) catalyst,
[0025] wherein the catalyst (d) used comprises zirconium compounds
soluble in the reaction mixture.
[0026] Since the reactor volumes required for the preparation of a
certain amount of diurethanes and/or polyurethanes is directly
dependent on the space-time yield of the reaction, the catalysis
can be optimized by use of the soluble zirconium compounds of the
present invention. This results in the following ecomonomic
advantages: the costs of the production plant can be minimized, the
polyurethane yield can be increased in existing production plants
and/or defined amounts of polyurethane can be produced with maximum
selectivity in existing production plants. Under identical reaction
conditions, the process of the present invention makes possible an
increase in the space-time yield by a factor of 3 in comparison
with the uncatalyzed reaction and by a factor of 2 when using the
zirconium acetate of the present invention in comparison with
aluminum acetylacetonate as described in EP-B-0 027 940. The
process of the present invention enables monomeric diurethanes
and/or polyurethanes, in particular aliphatic and cycloaliphatic
diurethanes, to be prepared advantageously in high space-time
yields and with maximum selectivity, thereby minimizing the
production costs.
[0027] According to the present invention, catalysts used are
zirconium compounds which are soluble in the reaction mixture,
particularly under the reaction conditions employed. Examples of
suitable soluble zirconium compounds are zirconium alkoxides of
linear or branched alcohols having from 1 to 10 carbon atoms,
preferably from 1 to 4 carbon atoms, for example zirconium
methanolate, ethanolate, n- and iso-propanolate, n-butanolate,
sec-butanolate, tert-butanolate, isomeric zirconium pentanolates,
such as tetrapentanolate, 2-methyl-2-butanolate, hexanolate,
2-ethylhexanolate, tetra-2-ethylhexanolate, octanolate, decanolate
and preferably zirconiumn n-butanolate, amine-substituted zirconium
compounds, such as tetradiethylaminozirconium, acetylacetonates,
such as zirconium acetylacetonate, zirconium
tetra-2-ethylhexanoate, zirconium(IV) trifluoroacetylacetonate,
tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionato)zirconium,
zirconium hexafluoroacetylacetonate, carboxylates of zirconium,
such as zirconium acetate, zirconium oxalate, zirconyl propionate,
zirconium butyrate and isomers thereof, zirconium tetraacrylate,
zirconium methacrylate, zirconium dimethacrylate dipropanolate,
zirconium(IV) dimethacrylate, zirconium
methacryloxyethylacetoacetate tri-n-propanolate and higher
carboxylates, such as zirconium citrates, zirconium lactate,
zirconium neodecanoate, cyclopentadienyl complexes of zirconium,
such as zirconocene diethoxide, zirconocene dichloride, zirconocene
chloride hydride, cyclopentadienylzirconium trichloride,
bis(pentamethylcyclopenta- dienyl)zirconium dichloride,
pentamethylcyclopentadienylzirconium trichloride, zirconcene
bis(trifluoromethanesulfonate), zirconium salts of inorganic acids
such as zirconium carbonate, zirconium hydroxide, zirconium
nitrate, zirconium sulfate, zirconium sulfide, zirconium phosphate,
zirconium pyrophosphate, zirconyl ammonium carbonate, zirconium
halides such as zirconium(IV) fluoride, zirconium(IV) chloride,
zirconium tetrabromide, zirconium tetraiodide, zirconyl chloride,
zirconyl perchlorate, sodium hexafluorozirconate, zirconates, such
as aluminum zirconate, ammonium hexafluorozirconate, bismuth
zirconate, lead zirconate, cadmium zirconate, cesium zirconate,
calcium zirconate, cerium zirconate, cobalt zirconate, potassium
hexafluorozirconate, potassium pentafluorozirconate, lithium
zirconate, magnesium zirconate, manganese zirconate, sodium
zirconate, rubidium zirconate, strontium zirconate, zinc zirconate
and other inorganic zirconium compounds such as zirconium
aluminide, zirconium boride, zirconium hydride, zirconium carbide,
zirconium molybdate, zirconium nitride, zirconium selenide,
zirconium telluride and zirconium tungstate.
[0028] Compounds which have been found to be very useful and are
therefore preferably used are: zirconium acetate, zirconium
acetylacetonate and, in particular, zirconium-n-butanolate.
[0029] The catalysts can be used in any amounts. For economic
reasons, very small amounts of catalyst are advantageously used.
Depending on their catalytic activity, which can easily be measured
experimentally, the zirconium compounds are advantageously used in
an amount of from 0.00001 to 1 mol percent, preferably from 0.0001
to 0.1 mol percent and in particular from 0.001 to 0.05 mol
percent.
[0030] The organic monomeric diurethanes and/or polyurethanes can
be prepared in the presence of the catalysts of the present
invention according to known methods by reacting polyamines with
carbonic acid derivatives, in particular urea, and alcohols with
removal of the ammonia formed.
[0031] Viewed purely formally, the process of the present invention
can be represented by the following equation: 1
[0032] a) Examples of suitable amines of the formula
R--(NH.sub.2).sub.n, where R is a polyvalent, unsubstituted or
substituted organic, preferably aromatic and in particular
aliphatic or cycloaliphatic, radical and n is an integer which
corresponds to the valence of R and is at least 2, preferably from
2 to 5 and in particular 2, are: aromatic polyamines which may be
unsubstituted or substituted on the arylene radical by, for
example, C.sub.1-C.sub.4-alkyl, C.sub.1-C.sub.4-alkoxy or halogen,
for example 2,4- and 2,6-tolylenediamines or their industrial
mixtures, 2,2'-, 2,4'- and preferably 4,4'-diaminodiphenylmethane
or mixtures of at least 2 of the specified isomers,
3,3'-dimethyl-4,4'-diaminobiphenyl, 1,2-bis(4-aminophenyl)ethane,
1,3- and 1,4-phenylenediamine, 1,4- and 1,5-diaminonaphthalene,
3,3',5,5'-tetraethyl-, 3,3',5,5'-tetraisopropyl-4-
,4'-diaminodiphenylmethane, 1,3,5-triaminobenzene,
2,4,6-triaminotoluene and polyphenylpolymethylenepolyamines and
also mixtures of Diaminodiphenylmethanes and
polyphenylpolymethylenepolyamines, which can be obtained according
to known methods by condensation of aniline and formaldehyde in the
presence of, preferably, mineral acids as catalyst or in the
absence of catalysts, aliphatic polyamines having from 2 to 19
carbon atoms, preferably from 3 to 13 carbon atoms and in
particular from 4 to 6 carbon atoms; these can have a
straight-chain or branched structure and contain as bridges
heteroatoms, eg. oxygen or sulfur, or divalent heterocyclic
radicals or arylene, preferably phenylene, radicals in bonded form,
for example ethylenediamine, 1,3- and 1,2-Propylenediamine,
2,2-dimethylpropylene-1,3-diamine, 1,4-butylenediamine,
2-ethylbutylene-1,4-diamine, 2-ethyl-2-butylbutylene- -1,4-diamine,
1,5-pentamethylenediamine, 2-methylpentamethylene-1,5-diamin- e,
2-ethyl-2-butylpentamethylene-1,5-diamine,
1,6-hexamethylenediamine, 2,2,4-trimethylhexamethylene-1,6-diamine,
1,8-octamethylenediamine, 1,10-decylenediamine,
1,12-dodecylenediamine, hexahydroxylylene-1,4-diami- ne and
1,4-xylylenediamine, and cycloaliphatic polyamines having from 5 to
12 carbon atoms, preferably from 6 to 12 carbon atoms, for example
1,2-, 1,3- and 1,4-cyclohexanediamine, hexahydrotolylene-2,4- and
-2,6-diamine and also the corresponding isomer mixtures, 4,4'-,
2,4'- and 2,2'-diaminodicyclohexylmethane and also the
corresponding isomer mixtures and
3-aminomethyl-3,5,5-trimethylcyclohexylamine. As polyamines,
preferably diamines, preference is given to using 2,4- and
2,6-tolylenediamine, 4,4'-, 2,4'- and 2,2'-diaminodiphenylmethane
and their isomer mixtures and also, in particular,
1,6-hexamethylenediamine and
3-aminomethyl-3,5,5-trimethylcyclohexylamine.
[0033] b) As carbonic acid derivative, preference is given to using
urea (b). Since urea forms an alkyl carbamate with alcohol under
the reaction conditions employed in the urethane formation, it is
also possible to use an alkyl carbamate as formative component (b)
in place of urea or together with urea. An alkyl carbamate can be
prepared in a preliminary stage, for example from urea and alcohol
which is advantageously used in excess, and this ester, for example
in the form of an alcoholic solution, can be reacted with the
polyamines in the presence of the soluble zirconium compounds as
catalyst. In a similar manner dialkyl carbonates formed as
by-products in the urethane formation or prepared separately can
also be used, so that mixtures of urea, alkyl carbamates and/or
dialkyl carbonate can be employed in place of urea.
[0034] Suitable alkyl carbamates have the formula H.sub.2N--COOR,
where R is an unsubstituted or substituted aliphatic,
cycloaliphatic or aromatic-aliphatic radical. Examples of suitable
compounds are alkyl carbamates based on primary aliphatic
monoalcohols having from 1 to 20 carbon atoms, preferably from 1 to
10 carbon atoms, for example methyl carbamate, ethyl carbamate,
propyl carbamate, n-butyl carbamate, isobutyl carbamate, 2- and
3-methylbutyl carbamate, neopentyl carbamate, pentyl carbamate,
2-methylpentyl carbamate, n-hexyl carbamate, 2-ethylhexyl
carbamate, heptyl carbamate, n-octyl carbamate, n-nonyl carbamate,
n-decyl carbamate and n-dodecylcarbamate, 2-phenylpropyl carbamate
and benzyl carbamate and based on secondary aliphatic and
cycloaliphatic monoalcohols having from 3 to 15 carbon atoms,
preferably from 3 to 6 carbon atoms, for example isopropyl
carbamate, sec-butyl carbamate, sec-iso-amyl carbamate, cyclopentyl
carbamate, cyclohexyl carbamate, tert-butylcyclohexyl carbamate and
bicyclo[2.2.1]heptyl carbamate. Preference is given to using methyl
carbamate, ethyl carbamate, propyl carbamate, butyl carbamate,
isobutyl carbamate, 2- and 3-methylbutyl carbamate, pentyl
carbamate, hexyl carbamate, 2-ethylhexyl carbamate, heptyl
carbamate, octyl carbamate and cyclohexyl carbamate.
[0035] If the urethane formation is carried out using urea in the
presence of dialkyl carbonates or preferably alkyl carbamates, the
dialkyl carbonates can be used, for example, in an amount of from
0.1 to 30 mol %, preferably from 1 to 10 mol %, or the alkyl
carbamates can be used, for example, in an amount of from 1 to 20
mol %, preferably from 5 to 15 mol %, based on the polyamine,
preferably diamine. However, particular preference is given to
using mixtures of dialkyl carbonates and alkyl carbamates in the
specified ratios. The dialkyl carbonates and/or carbamic esters
used are preferably ones whose alkyl radicals correspond to the
alkyl radical of the alcohol used.
[0036] The preparation of the monomeric organic polyurethanes,
preferably diurethanes, can also be carried out in the presence of
other carbonic acid derivatives, eg. polyurets, substituted ureas,
unsubstituted and substituted polyureas, oligourea-polyurethanes,
high-boiling oligomers and other by-products formed in the thermal
dissociation of the diurethanes and/or polyurethanes to give
diisocyanates and/or polyisocyanates. These carbonic acid
derivatives can, for example, be formed in the thermal dissociation
of the polyurethanes, isolated, if desired subjected to
intermediate storage or can be prepared in separate processes and,
if desired together with the urea (b) and/or alcohol (c), be
introduced into the polyurethane preparation. In continuous
processes for preparing organic polyisocyanates by thermal
dissociation of polyurethanes, such carbonic acid derivates from
the dissociation reactor can be recirculated to the urethane
formation.
[0037] c) Alcohols (c) which can be used for the process of the
present invention are any unsubstituted or substituted primary or
secondary aliphatic alcohols or aromatic-aliphatic alcohols and
also mixtures thereof. However, since the diurethanes and/or
polyurethanes are used in particular for preparing polyisocyanates,
it is preferably to select those whose boiling points are
sufficiently far from the boiling point of the polyisocyanate,
preferably diisocyanate, obtained by the thermal dissociation, so
that a virtually quantitative separation of the dissociation
products polyisocyanate, preferably diisocyanate, and alcohol is
possible.
[0038] For these reasons, preference is given to using primary
aliphatic monoalcohols having from 1 to 20 carbon atoms, preferably
from 1 to 10 carbon atoms, for example methanol, ethanol, propanol,
n-butanol, iso-butanol, 2- and 3-methylbutanol, neopentyl alcohol,
pentanol, 2-methylpentanol, n-hexanol, 2-ethylhexanol, n-heptanol,
n-octanol, n-nonanol, n-decanol, n-dodecanol, 2-phenylpropanol and
benzyl alcohol, secondary aliphatic and cycloaliphatic monoalcohols
having from 3 to 15 carbon atoms, preferably from 3 to 6 carbon
atoms, for example isopropanol, sec-butanol, sec-isoamyl alcohol,
cyclopentanol, cyclohexanol, 2,3- or 4-methylcyclohexanol and
4-tert-butylcyclohexanol, or mixtures of the alcohols specified,
but in particular n-butanol and/or iso-butanol.
[0039] To prepare the diurethanes and/or polyurethanes by the
process of the present invention, the primary organic diamines
and/or polyamines (a), preferably aliphatic or cycloaliphatic
diamines, can be reacted with urea (b) and alcohol (c) in such
amounts that the ratio of NH.sub.2 groups of the amines to urea (b)
and any alkyl carbamate and/or dialkyl carbonate to hydroxyl groups
of the alcohols (c) is 1:0.7-5:1-50, preferably 1:0.9-2:1-10 and in
particular 1:1.0 to 1.3:1.5-5. If the reaction is carried out in
the presence of dialkyl carbonates and/or preferably alkyl
carbamates, 1 mol of alkyl carbamate or dialkyl carbonate can be
used in place of 1 mol of urea. The reaction in the presence of the
soluble zirconium compounds as catalyst is usually carried out in
the range from 160.degree. to 300.degree. C., preferably from
180.degree. to 250.degree. C. and in particular from 185.degree. to
240.degree. C. and under a pressure which is, depending on the
alcohol used, from 0.1 to 60 bar, preferably from 1 to 40 bar.
These reaction conditions give reaction times of, for example, from
0.5 to 48 hours, preferably from 1 to 3 hours.
[0040] The reaction is advantageously carried out in the presence
of excess alcohol as solvent and reaction medium. It has here found
to be advantageous to immediately remove the ammonia formed from
the reaction mixture, for example by distillation. An apparatus
used for this purpose, eg. a distillation column, can be operated
at from 60 to 150.degree. C., preferably from 65 to 120.degree. C.,
so that deposition of ammonium carbamate, which is formed in small
amounts from ammonia and carbon dioxide from decomposition of urea,
can be avoided.
[0041] The diurethane and/or polyurethane preparation can be
carried out batchwise or continuously. In the case of the
continuous procedure, it has been found to be advantageous to
separate the alcohol, the dialkyl carbonates, in so far as these
have been formed or are present in the reaction mixture, or alkyl
carbamates or mixtures of at least two of these components from the
reaction mixture after the urethane formation is complete and
preferably recirculate them to the beginning of the reaction. To
separate off the components, the reaction mixture is advantageously
depressurized from the pressure level at the beginning of the
reaction to a pressure in the range from 1 to 500 mbar, preferably
from 10 to 100 mbar. This gives gaseous vapors containing most of
the alcohol and from 0 to 30% by weight, preferably from 1 to 10%
by weight, of dialkyl carbonate and/or from 1 to 50% by weight,
preferably from 1 to 20% by weight, of alkyl carbamate, and a
liquid product consisting essentially of the monomeric
polyurethane, preferably diurethane, and possibly
oligourea-polyurethanes and high-boiling oligomers.
[0042] The vapors obtained can be fractionated in subsequent
purification steps, advantageously by distillation, preferably by
rectification, and the useful products thus isolated, viz. alcohol
and alkyl carbamate, individually or as a mixture, can preferably
be recirculated to the beginning of the reaction to form the
monomeric polyurethanes.
[0043] The liquid product can be separated by distillation, eg.
using a conventional distillation unit, preferably a thin-film
evaporator, at, for example, from 170.degree. to 240.degree. C.,
preferably from 180.degree. to 230.degree. C. and under a pressure
of from 0.01 to 5 mbar, preferably from 0.1 to 2 mbar, into a
useful product containing the polyurethanes, preferably
diurethanes, and the lower-boiling by-products, and an unusable
residue which is discarded.
[0044] The useful product can be converted directly into
diisocyanates and/or polyisocyanates by thermal dissociation or the
lower-boiling by-products can be separated off, eg. by
distillation, and the diurethanes and/or polyurethanes obtained can
be additionally purified by distillation or recrystallization,
advantageously from other solvents.
[0045] The organic polyurethanes, preferably diurethanes, prepared
by the process of the present invention are preferably used for
preparing organic polyisocyanates which in turn are used for
preparing polyisocyanate polyaddition products.
EXAMPLES
Comparative Example I
[0046] In a 1.5 l stirring autoclave fitted with a pressure
maintenance device and a reflux condenser operated using water
heated to 90.degree. C.,
[0047] 104.4 g (0.9 mol) of hexamethylenediamine (HDA),
[0048] 135 g (2.25 mol) of urea and
[0049] 532.8 g (7.2 mol) of n-butanol
[0050] were reacted at 210.degree. C. under reflux and under a
pressure of 9 bar.
[0051] The ammonia formed was continuously removed from the
reaction mixture.
[0052] The course of the reaction was monitored by taking samples
from the reaction mixture every hour and analyzing them by liquid
chromatography.
[0053] After a reaction time of 6 hours, the reaction system was
still not in a steady state with regard to all by-products formed.
The hexamethylenediurethane (HDU) content of the reaction product
(660 g) was 40% by weight. This gave a space-time yield of less
than 53 [g/l.multidot.h].
Comparative Example II
[0054] The procedure of Comparative Example I was repeated, but the
reaction was carried out in the presence of 14.6 mg of aluminum
acetylacetonate (0.005 mol %, based on HDA).
[0055] The reaction system had reached a steady state after 4
hours, with the HDU content of the reaction product (661 g) being
40% by weight. This gave space-time yield of 80
[g/l.multidot.h].
Comparative Example III
[0056] The procedure of Comparative Example I was repeated, but the
reaction was carried out in the presence of 16 mg of iron
acetylacetonate (0.005 mol %, based on HDA).
[0057] The reaction system had reached a steady state after 4
hours, with the HDU content of the reaction product (660 g) being
41% by weight. This gave a space-time yield of 82
[g/l.multidot.h].
Example 1
[0058] The procedure of Comparative Example I was repeated, but the
reaction was carried out in the presence of 22 mg of zirconium
acetylacetonate (0.005 mol %, based on HDA).
[0059] The reaction system had reached a steady state after 2
hours, with the HDU content of the reaction product (663 g) being
41% by weight. This gave a space-time yield of 164
[g/l.multidot.h].
Example 2
[0060] The procedure of Comparative Example I was repeated, but the
reaction was carried out in the presence of 10 mg of zirconium
acetate (Zr(C.sub.2H.sub.3O.sub.2).sub.1.4(OH).sub.2.6) (0.005 mol
%, based on HDA).
[0061] The reaction system had reached a steady state after 2
hours, with the HDU content of the reaction product (662 g) being
42% by weight. This gave a space-time yield of 168
[g/l.multidot.h].
Example 3
[0062] The procedure of Comparative Example I was repeated, but the
reaction was carried out in the presence of 21.6 mg of an 80%
strength by weight zirconium butanolate solution in n-butanol
(0.005 mol %, based on HDA).
[0063] The reaction system had reached a steady state after 2
hours, with the HDU content of the reaction product (662 g) being
43% by weight. This gave a space-time yield of 172
[g/l.multidot.h].
Comparative Example IV
[0064] In a 1.5 l stirring autoclave fitted with a pressure
maintenance device and a reflux condenser operated using water
heated to 90.degree. C.,
[0065] 170 g (1 mol) of isophoronediamine (IPDA),
[0066] 150 g (2.50 mol) of urea and
[0067] 592 g (8.0 mol) of n-butanol
[0068] were reacted at 210.degree. C. under reflux and under a
pressure of 8 bar. The ammonia formed was continuously removed from
the reaction mixture.
[0069] The course of the reaction was monitored by taking samples
from the reaction mixture every hour and analyzing them by liquid
chromatography.
[0070] After a reaction time of 6 hours, the reaction system was
still not in a steady state with regard to all by-products formed.
The space-time yield was less than 60 [g/l.multidot.h].
Example 4
[0071] The procedure of Comparative Example IV was repeated, but
the reaction was carried out in the presence of 24.4 mg of
zirconium acetylacetonate (0.005 mol %, based on IPDA).
[0072] The reaction system had reached a steady state after 2
hours, giving a space-time yield of 170 [g/l.multidot.h] of
isophoronediurethane (IPDU).
Comparative Example V
[0073] In a 1.5 l stirring autoclave fitted with a pressure
maintenance device and a reflux condenser operated using water
heated to 90.degree. C.,
[0074] 104.4 g (0.9 mol) of HDA,
[0075] 263 g (2.25 mol) of n-butyl carbamate and
[0076] 366 g (4.95 mol) of n-butanol
[0077] in the presence of 14.6 mg of aluminum acetyl acetonate
(0.005 mol %, based on HDA) were reacted at 210.degree. C. under
reflux and under a pressure of 9 bar. The ammonia formed was
continuously removed from the reaction mixture.
[0078] The course of the reaction was monitored by taking samples
from the reaction mixture every hour and analyzing them by liquid
chromatography.
[0079] After a reaction time of 6 hours, the reaction system was
still not in a steady state with regard to all by-products formed.
The HDU content of the reaction product (665 g) was 40.4% by
weight. This gave a space-time yield of less than 54
[g/l.multidot.h].
Example 5
[0080] The procedure of Comparative Example V was repeated, but the
reaction was carried out in the presence of 21.9 mg of zirconium
acetylacetonate (0.005 mol %, based on HDA).
[0081] The reaction system had reached a steady state after 4
hours, with the HDU content of the reaction product (663 g) being
42.6% by weight. This gave a space-time yield of 83
[g/l.multidot.h].
Comparative Example VI
[0082] In a cascade of 4 stirred reactors,
[0083] 600 g/h of HDA,
[0084] 700 g/h of urea and
[0085] 2200 g/h of n-butanol
[0086] were reacted continuously under the following
conditions:
1 1st stirred reactor: volume: 25 1 pressure: 11 bar temperature:
218.degree. C. feed: 600 g/h of HDA 700 g/h of urea 2200 g/h of
n-butanol condensate: 14 1/h n-butanol 2nd stirred reactor: volume:
12.5 1 pressure: 11 bar temperature: 222.degree. C. 3rd stirred
reactor: volume: 12.5 1 pressure: 11 bar temperature: 227.degree.
C. 4th stirred reactor: volume: 12.5 1 pressure: 11 bar
temperature: 230.degree. C.
[0087] The HDU content of the reaction product from the cascade
(3100 g/h) was 51.6% by weight, giving a space-time yield of 26
[g/l.multidot.h]. The HDU yield, based on HDA used, was 97.9%.
Comparative Example VII
[0088] In a cascade of 4 stirred reactors,
[0089] 1000 g/h of HDA,
[0090] 1200 g/h of urea and
[0091] 3700 g/h of n-butanol
[0092] were reacted continuously under the following
conditions:
2 1st stirred reactor: volume: 25 1 pressure: 11 bar temperature:
218.degree. C. feed: 1000 g/h of HDA 1200 g/h of urea 3700 g/h of
n-butanol condensate: 20 1/h of n-butanol catalyst: 418 mg of
aluminum acetylacetonate (0.015 mol %, based on HDA) 2nd stirred
reactor: volume: 12.5 1 pressure: 11 bar temperature: 222.degree.
C. 3rd stirred reactor: volume: 12.5 1 pressure: 11 bar
temperature: 227.degree. C. 4th stirred reactor: volume: 12.5 1
pressure: 11 bar temperature: 230.degree. C.
[0093] The HDU content of the reaction product from the cascade
(5200 g/h) was 49.4% by weight, giving a space-time yield of 41
[g/l.multidot.h]. The HDU yield, based on HDA used, was 94.3%.
Example 6
[0094] In a cascade of 4 stirred reactors,
[0095] 1300 g/h of HDA,
[0096] 1550 g/h of urea and
[0097] 4800 g/h of n-butanol
[0098] were reacted continuously under the following
conditions:
3 1st stirred reactor: volume: 25 1 pressure: 11 bar temperature:
218.degree. C. feed: 1300 g/h of HDA 1550 g/h of urea 4800 g/h of
n-butanol condensate: 26 1/h of n-butanol catalyst: 127 mg of
zirconium acetate (0.005 mol %, based on HDA) 2nd stirred reactor:
volume: 12.5 1 pressure: 11 bar temperature: 222.degree. C. 3rd
stirred reactor: volume: 12.5 1 pressure: 11 bar temperature:
227.degree. C. 4th stirred reactor: volume: 12.5 1 pressure: 11 bar
temperature: 230.degree. C.
[0099] The HDU content of the reaction product from the cascade
(6800 g/h) was 51.0% by weight, giving a space-time yield of 56
[g/l.multidot.h]. The HDU yield, based on HDA used, was 98.0%.
[0100] The Comparative Examples VI and VII and Example 6 show that
in a given, continuously operated cascade of stirred reactors the
high HDU yields required for the subsequent dissociations are
achieved in the highest space-time yield using the soluble
zirconium compounds of the present invention as catalyst. In
comparison with the uncatalyzed reaction (Comparative Example VI),
the zirconium acetate used as catalyst according to the present
invention (Example 6) enables the same cascade of stirred reactors
to be operated at more than double the loading while maintaining
the prescribed HDU quality.
* * * * *