Note: Descriptions are shown in the official language in which they were submitted.
Mo-1631-G
LeA 16,670-G
~797 L~ 4
A PROCESS FOR THE PRODUCTION OF BISULPHITE ADDITION
PRODUCTS OF POLYISOCYANATE PREPO~YMERS IN WATER
sack~round of the Invention
The production of addition products from isocyanates
and acid salts of sulphurous acid in the aqueous phase is
- already known (German Patent No. 859,156~. This process is
based on the reaction of relatively low molecular weight mono-
and poly-isocyanates.
It is also generally known (see e. g. German Offen-
legungsschrift 2,307,563) that bisulphite adducts of relatively
high molecular weight polyisocyanate prepolymers cannot be
produced under these conditions. The conversion oE relatively
high molecular weight polyisocyanate prepolymers into the
bisulphite addition products only takes place when relatively
large quantities of organic water-miscible solvents are added
to the aqueous phase. Unfortunately, this complicates the -
process in terms of practical working because the use of
organic solvents involves a number of disadvantages, including,
or example, the costs of the solvent, the outlay involved in
its recovery, the in1ammability o~ the solvent and the toxicity
of the solvent vapors. The volume-time yield of this process
and, hence, itseconomy is extremely unsatisfactory.
DESCRIPTION OF THE INVENTION
It has now surprisingly been found that these dis-
advantages can be eliminated by using non-ionically hydro-
philised prepolymers for the productio;n of the bisulphite
adducts of polyisocyanate prepolymers. The reaction between
the prepolymers thu5 modified and the salt-like bis1ulphites
takes place in water at room temperature in the abslence of
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~797~
organic solvents, giving aqueous homogeneous solutions of the
bisulphite addition products of polyisocyana-te prepolymers.
~ccordingly, this new process enables bisu:Lphite addition
products of polyisocyanate prepolymers to be obtained in an
extremely simple manner.
Accordingly, the present invention is directed to a
process for the production of bisulphite addition products o~
polyioscyanate prepolymers by reacting the polyisocyanate
prepolymers with water-soluble bisulphites, wherein
a) the polyisocyanate prepolymers used are isocyanate
group containing reaction products of
(i) low molecular weight, organic pol~isocy~nates
with
(ii) less than stoichiometric amounts of organic
polyhydroxyl compounds which have been
modified by the incorporation of non-ionic
hydrophilic groups in such a way that the
polyisocyanate prepolymers can be emulsified
in water, and
b) reaction with the bisulphites is carried out in
the aqueous phase in the absence of organic
solvents.
The polyisocyanate prepolymers used in the process
according to the invention are reaction products containing
terminal isocyanate groups o~ excess quantities of diisocyanates
corresponding to the formula;
R(NCO)2 :
with polyether polyols corresponding to the formula
A(OH)n
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~L~i7974~
These reaction products, in general, correspond to the ~;
formula: :
A-(0-C-NH-R-NCO)n
O " ' :'
In the above formu~a:
A represents a radical of the type obtained by removing ~ ~:
the hydroxyl groups from an _-functional polyalkylene
oxide polyol which has a molecular weight of from 500
to 8000, preferably from 1000 to 6000, and
8 to 70%, preferably 8 to 30 %
of whose alkylene oxide segments consist of ethylene
oxide segments and whose remaining alkylene oxide
segments are propylene oxide, butylene oxide or
styrene oxide segments, and preferably propylene ~.
oxide segments; .
R represents a radical of the type obtained by removing
the isocyanate groups from an organic diisocyanate
which has a molecular weight in the range from 112
to 1000, preferably an aliphatic hydrocarbon radical
having 4 to 12 carbon atoms, a cycloaliphatic hydro-
carbon radical having 6 to 15 carbon atoms, an
aromatic hydrocarbon radical having 6 to 15 carbon
atoms or an araliphatic hydrocarbon radical having
7 to 15 carbon atoms, and with particular preference - :~
a hydrocarbon radical of the type obtained by removing ~ ;
the isocyanate groups from hexamethylene diisocyanate
or 2,4- and 2,6-diisocyanatotoluene;
- n is an integer from 2 to 4, preferably 2 or 3, mo~t prefer-
ably 3.
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4~
The polyether polyols AtOH)n are preferably produced
by the alkoxylation known per se of a starter molecule of
n-functionality, in the context of the alkylene oxide addition
reaction, in the presence of ethylene oxide and, optionally,
propylene oxide, isomeric butylene oxides, styrene oxide, and
preferably propylene oxide, the aEorementioned alkylene oxides
being used in any order or even in admixture with one another.
It is preferred to use ethylene oxide and propylene oxide in
any order or in admixture in such quantities that the alkylene
oxide segments of the polyether polyol correspond to the com-
position gi~en above. Particularly preferred polyether polyolsare those which contain terminal polyethylene oxide segments
in a quantity which corresponds to between 8 and 30 ~ of the
total number o~ alkylene oxide units. In addition to the
aforementioned alkylene oxides, it is also possible to use
tetrahydrofuran for the production of the polyethers.
Preferred starter molecules are those corresponding
to the formula:
B(OH)m,
in which
B represents hydrogen or an aliphatic hydrocarbon
radical having 2 to 18 carbon atoms and preferably ~ :
having 2 to 6 carbon atoms, and
m is identical with _ where B is a hydrocarbon radical,
or is the number 1 where B is hydrogen.
In addition to these preferred starter molecules,
it is also poss~ble to ~se any other c~mpounds o~ n~$unctional-
ity, in the context of the alkylene oxide addition re~ct:ion
which are suitable for the addition of alkylene oxides. In
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1~797~L
this case, however, the molecular weight of the starter
molecule is pre~erably selected in such a way that the
proportion of polyalkylene oxide segments in the polyether
polyol A(OH)n amounts to at least 80~ by weight, based on
the total weight of the polyether polyol.
Starter molecules suitable for producing the poly-
ether polyols include, for example, water, ethylene glycol,
1,2-propane diol, trimethylene glycol, 1,2-butane diol, 2,3-
butane diol, tetramethylene glycol, blycerol, 1,2,6-hexane
triol, trimethylol propane, trimethylol ethane, pentaerythritol
or even nitrogen-containing starter molecules such ~s tri-
ethanolamine, ethylene diamine, aniline or aminoethanol. ..
Generally, it is also possible to use aromatir starter mole-
cules such as resorcinol or bispheno.l A.
Suitable isocyanates R(NCO)2 include, for example,
ethylene diisocyanate, tetramethylene diisocyanate, hexa-
methylene diisocyanate, 1,12-dodecane diiRocyanate, cyclo-
butane-1,3-diisocyanate, cyclohexane-1,3-diisocyanate and
-1,4-diisocyanate, also mixtures of these isomers, l-isocyanato-
3,35-trimethyl-5-isocyanatomethyl cyclohexane, 2,4- and
2,6-hexahydrotolylene diisocyante and mixtures of these isomers,
hexahydro-1,3- and/or -1,4-phenylene diisocyanate, perhydro-
2,4'- and/or -4,4'-diphenyl methane di.isocyanate, 1,3- and
1,4-phenylene diisocyanate, 2,4- and 2,6-tolylene diisocyanate
and mixtures of these isomers, diphenyl methane 2,4' and/or
-4,4'- diisocyanate and naphthylene-1,5-diisocyanate.
Generally, it is also possible in the process according
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to the invention to us~e polyisocyanate prepoly~ers which
have been produced from polyisocyanates of hi~her functionality,
for example from triphenyl methane-4,4', 4"-tri-isocyanate or
from polyphenyl polymethylene polyisocyanates o~ the type
obtained by condensing aniline with formaldehyde, followed by
phosgenation, and described for example in British Patents
874,430 or 848,671.
The polyisocyan~te prepolymers suitable for the
process according to the invention are obtained by the conven-
tional polyisocyanate polyaddition process by reacting anexcess of polyisocyanates with the hydrophilic polyether poly-
ol~. Depending upon the purpose Eor which the bisulphite
addition product is lnt~nded, it may be of advantage to
separate the excess polyisocyanate from the polyisocyanate
prepolymer after the reaction, (for example, by high vacuum
thin-layer evaporation), in order to obtain a polyisocyanate
substantially free from monomers. However, this additional
operation is not absolutely essential to the process according
to the invention.
As already mentioned, the most pre~erred poly-
isocyanate prepolymers are those whose polyether component
contains from 8 to 30 % of ethylene oxide segments ~CH2-CH2-O-,
based on the total content of alkylene oxide segments~ These
highly preferred polyisocyanate prepolymers are insolu~le in
water because of their low proportion of hydrophilic chain .
segments, but are largely hydrophobic. Accordingly, it is
particularly surprising that, in particular, this minimal
hydrophilic modification is sufficient in order to be able to
work without solvents in accordance with the inYention~
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1~>79~4 ` ~
The polyisocyanate prepolyme~s ùstëd in the process
according to the invention may be reacted wit~ aqueous
bisulphite solutions bot~ in the presence and in the absence
of emulsifying aids. In this respect, the nature of the
cation of the bisulphite used is largely unimportant. The
only important factor is that water-soluble bisulphites should
be used. It is preferred to use sodium, potassium or ammonium
bisulphites in the form of their aqueous solutions. When the
reactants are mixed, an emulsion is initially formed. Reaction
of the isocyanate groups with the bisulphite anions takes
place more quickly the more hydrophilic the starting polyether,
the emulsion graclually changing into a clear homogeneous
solution. Depending upon the polyether polyol and poIyisocyan-
ate used, it is also possible to obtain turbid solutions.
Homogeneous bisulphite adduct solutions, which can be further `
diluted with water as required, are thus obtained.
Emulsifiers suitable for use in the process according
to the invention include any standard, commercial-grade
surface-active substances of the type known and used for the
preparation of oil-in-water emulsions. For example, it is
possible to use non-ionic compounds containing hydrophobic
hydrocarbon units and hydrophilic polyethylene ether glycol
units such as, for example, 3-benzyl-4-hydroxy ~iphenyl poly-
glycol ethers, or even ionic emulsifiers such as, for example,
the sodium salt of a standard commercial-grade paraffin
sulphate or mixtures of these emulsifying aids~ The emul- ;
sifiers can be used in quantities of from 0 to 20 % by weight
and prefer~bly in quantitles of from 0 to lO ~ by weight~
based on the quantity of the p~ep~l~mer~
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1~7979~4
For the purpos~s of the invention r the total con-
centration of ~isulphite anions should be sufficient to react
with all the isocyanate groups present. Preferably a slight
excess should be present. A ratio of moles of bisulphite
anions to NCO~equivalents of 1,01 to 1,5:1 is particularly
preferred. However, it is,of course, also possible to react
only part, for example 60 to 90 %, of the NC0-groups with
bisulphite, especially in cases where the presence of excess
salt is to be avoided.
The solids content, expressed as bisulphite addition
products, of the solutions obtained by the proce3s according
to the invention generally amounts to between 1 and 80%,
and preerably to between 20 and 60~ In this concentration
range, the corresponding polyisocyanate prepolymers may be
reacted with aqueous bisulphite anion solutions to form their
bisulphite adducts in the absence of organic solvents.
Depending upon requirements and intended application,
additives soluble or emulsifiable in water may be stirred into
these bisulphite adduct solutions in order to improve their
storage properties or to adjust pH, vi~c09ity, clarity,
pourability and the like, For example, it is generally
advisable to adjust the pH-value of the bisulphite adduct
solutions in the acid range, i,e. to pH~ 3, in order to obtain
adequate storage stability. This result can be obtained for
example, by adding from 0,5 to 5~ by weight, based on the
total weight, o~ strong inorganic or organic acids such as,
for example, sulphuric acid or paratoluene sulphonic acid.
However, adjustment of the pH-value in the strongly acid
range may also be obtained by the addition of hydrogen
peroxide, in which case the bisulphite anions present in
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97~
excess are oxidized into the corresponding s~rongly acid
bisulphate anions, The bisulphite adduct solutions thus
stabilized may be stored almost indefinitely at room
temperature.
The aqueous solutions of the bisulphite addition
proaucts of polyisocyanate prepolymers obtaIned by the process
according to the invention may be used for applications where
water~soluble masked polyisocyanate prepolymers are employed.
By virtue of the fact that these bisulphite adducts are
readily and economically available, these applications are
particularly attractive. ~hus, the bisulphite adduct solutions
may be used or example as binders ~or chipboard, as adhesives,
impregnating agents Eor plastics, crosslinking agents ~or emul-
sions, dispersions or aqueous solutions of isocyanate~reactive
precondensates, hardening taking place under heat or steam.
The bisulphite adduct solutions obtained by the pro-
cess according to the invention are particularly suitable for
use as finishing preparations or sheet-form textiles of nat-
ural fibers or synthetics and mixtures thereof. They produce
an improvement in the wearing properties, feel, surEace
stability, crease resistance~ elasticity and, hence, recovery.
They also improve the scuffing resistance of the articles pro--
duced from the sheet-form textiles, and reduce their tendency
towards pilling and snagging. The treated textiles obtained
show a high level of resistance to washing and dry cleaningt
As already known (DOS 2,307~563), the bisulphite
adduct solutions can be used ~or improving the dimensional
st~bility and also ~or the non-matt finishing of w~Ven ~nd
knitted ~abrics of wool or wool mixtures. The bisulphite
adducts ohtained by the new process described herein are
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~)79744
distinguished ~y non-matting effects in the finishing of wool
comparable with those of, for example, conventional hydro-
phobic bisulphite adducts~
To obtain special effects, the bisulphite adducts
may be combined with other inishes such as, for example,
plastics dispersions (acrylate-based or polyurethane-based,
etc.), with plasticizers, crease-proofing agents, nonslip
agents, antielectrostatic agents, hydrophilizing agents,
hydrophobizing agents, and the like. The resistance to
washing and dry cleaning o the textiles obtainable with
aerylate and polyurethane dispersions are diskinetly inereased
by the addition of the bisulphite adduet solution.
By virtue of their low proportion of hydrophilie
eomponents, the preferred produets o~ the proeess aeeording ~: ~
to the invention obtained from the preferred starting materials ~ ;.
referred to above are suffieiently hydrophobie to guarantee
favorable finishing effeets, even after repeated washing.
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EXAMPLE 1
A hydrophilized polyisocyanate prepolymer is prepared
by reacting 2500 g of a trimethylol-propane!-started trifunc-
tional polyether polyol having an OH-number of 56.8, 17% of
whose alkylene oxide segments consist of terminally arranged
ethylene oxide segments and 83% consist of propylene oxide
segments, with 1270 g of hexamethylene diisocyanate over a
period of 2 hours at a temperature of 120C, The excess
hexamethylene diisocyanate is substantially separated off by
thin layer distillation n vacuo, leaving a polyisocyanate
propolymer having an NCO-content of 3.64 ~, 275 g of this
NCO-prepolymer are mixed for 10 minutes at 2800 rpm with 28 g
o~ a s~and~rd commercial-grade emul~ifier ~olution (50
s~lium
aqueous solution of a mixture of equal parts o ~(parain
sulfona~e and oxyeth~la~ed ~ony~-pheno~ 28 g of
sodium bisulphite and 640 g o water. A stable emulsion is
initially formed, gradually changing into a homogeneous solu-
tion over a period o 4 hours. A 30 %, slightly turbid com-
pletely water-dilutable bisulphite adduct solution is obtained.
EXAMPLE 2
A 50 ~ bisulphite adduct solution is prepared by
mixing 458 g o the polyisocyanate prepolymer prepared in
accordance with Example 1 with 46 g of the emulsifier
solution mentioned in Example 1, 46 g of sodium bisulphite
and 420 g o water. Ater standing overnight, a clear
aqueous bisulphite adduct solution is obtained. It can be
diluted with water in any ratio. This solution can be stored
indefinitely after 30 g o$ paratoluene sulphonic acid h~ve
been stirred in .
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EXAMPLE 3
A 50 % bisulphite adduct solution o~ the same poly-
isocy~nate prepolymer as in Example 1 is prepared by reacting
230 g of this prepolymer with 23 g o~ sodium bisulphite in
232 g of w~ter in the absence of an emulsi~:ier. After standing
overnight, a turbid, but homogeneous bisulphite adduct solution
is obtained.
EXAMPLE 4 ~-
Polyisocyanate prepolymers based on the following
polyol polyethers and freed from excess hexamethylene diiso-
cyanate are produced in accordance with Example 1.
Polyol polyether
Prepolymer Functionality OH- Number of ethylene
number oxide segments in
% based on the to-
tal number of alky-
lene oxide segments
_ ,
A 3 56.3 20
B 4 56.9 20
C 2 109 20
D 3 58 25
E 4 59.~ 25
F 3 56.5 30
G 3 57,6 55
H 3 34 73
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~079744
Prepolymers A, D, F and G were based on alkoxylated trimethylol-
propane; prepolymers B and E were based on a:lkoxylated penta-
erythritol; prepolymer C was based on alkoxylated 1,2-propane
diol. In all polyetherpolyols the ethylen~oxide segments were
terminal. Besides ethylenoxide segment~ all polyetherpolyol~
contained propylene oxide segments exclusively.
The prepolymers A to G may be reacted with sodium bisulphite
in accordance with Example 2 and ~ to ~orm corresponding ~0 %
bisulphite adduct solutions.
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~797~
E~AMPLE 5
In order to make cleax the adequately hydrvphilic
character of the polyisocyanate prepolymers used, as required
in accordance with the invention, the following NCO-prepolymers
were prepared on the basis of propoxylated trimethylolprop~m~
with 5 % of terminal ethylene oxide unit~ in the case K and
hexamethylene diisocyanate:
Polyol polyether
__ _
PrepolymerFunctionality OH- Number of ethylene
number oxide segments in %
based on the total
number of alkylene
oxide segments
J 3 56 0
K 3 55.5 5
These two NCO-prepolymers cannot be con~erted into
their bisulphite adducts by the process according to the
invention. The reaction mixture undergoes phase separation,
the organic phase representing a swollen mass which is totally
insoluble in water after only a few hours.
EXAMPLE 6
290 g ~0.1 mol) of a trifunctional trimethylol-
propane-started polyether polyol having an OH-numbe~ of 58,
25 % of whose alkylene oxide segments consist of ethylene
oxide segments and 75 % consist of propylene oxide segments,
are reacted for 3 hours at 110C with 100 g (0.6 mol) of
hexamethylene diisocyanate. The reaction mixture obtained
then has an NCO-value of 9.25 %. 195 g of this untreated
polyisocyanate prepolymer axe emulsi~ied with 19.5 g of the
emulsi~ier solution mentioned in Example 1~ 57 g of sodium
bisulphite in 233 g of water. ~ somewhat turbid~ hon~ogeneou~
3Q aqueous solution of the bisulphite adduct mixture of the
- NCO-prepolymer and the excess hexamethylene diisocyanate is
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; , . ,, ~ .
~:9'7974~
formed after st~,nding ove~ni~ht ,,
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