U.S. patent application number 11/732575 was filed with the patent office on 2007-11-22 for polyurethane foams for wound management.
Invention is credited to Melita Dietze, Burkhard Fugmann, Rolf Gertzmann, Michael Heckes, Michael Mager, Thorsten Rische, Daniel Rudhardt.
Application Number | 20070270730 11/732575 |
Document ID | / |
Family ID | 38457916 |
Filed Date | 2007-11-22 |
United States Patent
Application |
20070270730 |
Kind Code |
A1 |
Rische; Thorsten ; et
al. |
November 22, 2007 |
Polyurethane foams for wound management
Abstract
The invention relates to a process for producing polyurethane
foams for wound management. These polyurethane wound dressing foams
are prepared by a process comprising frothing and drying of a foam
foaming composition, which comprises a polyurethane dispersion and
specific coagulants.
Inventors: |
Rische; Thorsten; (Unna,
DE) ; Mager; Michael; (Leverkusen, DE) ;
Heckes; Michael; (Krefeld, DE) ; Rudhardt;
Daniel; (Koln, DE) ; Gertzmann; Rolf;
(Leverkusen, DE) ; Dietze; Melita; (Erkrath,
DE) ; Fugmann; Burkhard; (Ratingen, DE) |
Correspondence
Address: |
BAYER MATERIAL SCIENCE LLC
100 BAYER ROAD
PITTSBURGH
PA
15205
US
|
Family ID: |
38457916 |
Appl. No.: |
11/732575 |
Filed: |
April 4, 2007 |
Current U.S.
Class: |
602/46 ;
521/170 |
Current CPC
Class: |
A61L 15/26 20130101;
A61L 15/425 20130101; A61P 17/02 20180101; Y10S 514/945 20130101;
A61L 15/26 20130101; C08L 75/04 20130101 |
Class at
Publication: |
602/046 ;
521/170 |
International
Class: |
A61F 15/00 20060101
A61F015/00; C08G 18/00 20060101 C08G018/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 8, 2006 |
DE |
102006016636.1 |
Claims
1. A process for producing polyurethane wound dressing foams
comprising frothing and drying of a polyurethane foam forming
composition, wherein said polyurethane foam forming composition
comprises (I) at least one aqueous, anionically hydrophilicized
polyurethane dispersion, and (II) at least one cationic
coagulant.
2. The process of claim 1, wherein (I) said aqueous, anionically
hydrophilicized polyurethane dispersion comprises the reaction
product of: A) one or more isocyanate-functional prepolymers which
comprises the reaction product of: A1) at least one organic
polyisocyanate, with A2) at least one polymeric polyols having a
number-average molecular weight in the range from 400 to 8000 g/mol
and an OH functionality in the range from 1.5 to 6, and A3)
optionally, one or more hydroxyl-functional compounds having
molecular weights in the range from 62 to 399 g/mol, and A4)
optionally, one or more isocyanate-reactive, anionic or potentially
anionic and optionally nonionic hydrophilicizing agents; with B)
one or more compounds selected from the group consisting of: B1)
optionally, one or more amino-functional compounds having molecular
weights in the range from 32 to 400 g/mol, and B2) one or more
amino-functional, anionic or potentially anionic hydrophilicizing
agents; in which the free NCO groups of A) are reacted in whole or
in part with chain extension, and in which the prepolymers are
dispersed in water either before, during or after the reaction with
component B), and with any potentially ionic groups present being
converted into the ionic form by partial or complete reaction with
a neutralizing agent.
3. The process according to claim 2, wherein component A1) said
organic polyisocyanate is selected from the group consisting of
1,6-hexamethylene diisocyanate, isophorone diisocyanate, the
isomeric bis(4,4'-isocyanatocyclohexyl)methanes and mixtures
thereof, and component A2) said polymeric polyol comprises at least
70% by weight, based on 100% by weight of A2), of a mixture
comprising one or more polycarbonate polyols and one or more
polytetramethylene glycol polyols.
4. The process according to any one of claim 1, in which component
(II) said cationic coagulant comprises an acrylamide copolymer
which comprises structural units of the general formulae (1) and
(2): ##STR2## wherein in Formula (2): R: represents C.dbd.O,
--COO(CH.sub.2).sub.2-- or --COO(CH.sub.2).sub.3--; and X.sup.-:
represents a halide ion.
5. The process of claim 1, additionally comprising (III) one or
more auxiliary agents and/or additive materials.
6. The process of claim 5, in which (III) said auxiliary agents
and/or additive materials comprise foam formers and stabilizers
which are selected from the group consisting of fatty acid amides,
sulfosuccinamides, hydrocarbyl sulfonates, hydrocarbyl sulfates,
fatty acid salts and/or alkylpolyglycosides.
7. The process of claim 6, in which the foam formers comprise
mixtures of sulfosuccinamides and ammonium stearates, with the
mixtures containing from 50 to 70% by weight of
sulfosuccinamides.
8. Polyurethane wound dressing foams produced by the process of
claim 1.
9. The polyurethane wound dressing foams of claim 8, in which the
polyurethane foam is characterized by a microporous, open-cell
structure and a density of less than 0.4 g/cm.sup.3 in the dried
state.
10. The polyurethane wound dressing foams of claim 8, wherein the
polyurethane foams have a physiological saline absorbency of 100 to
1500% (mass of liquid taken up, based on the mass of dry foam) and
a water vapor transmission rate in the range from 2000 to 8000 g/24
h*m.sup.2.
11. Polyurethane foam forming compositions comprising (I) at least
one aqueous, anionically hydrophilicized polyurethane dispersion,
and (II) at least one cationic coagulant.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATION
[0001] The present patent application claims the right of priority
under 35 U.S.C. .sctn.119 (a)-(d) of German Patent Application No.
10 2006 016 636.1, filed on Apr. 8, 2006.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a process for producing
polyurethane wound dressing foams comprising polyurethane wound
dressing foams foams which are frothed and dried, in which the
polyurethane foams comprise one or more polyurethane dispersions
and one or more coagulants.
[0003] Polyurethane wound dressing foams are known to be suitable
for treating exsudating wounds. Due to their high absorbency and
their good mechanical properties, polyurethane foams produced by
reaction of mixtures of diisocyanates and polyols or NCO-functional
polyurethane prepolymers with water in the presence of certain
catalysts and also (foam) additives are generally used. Aromatic
diisocyanates are generally employed. Numerous forms of these
processes for producing polyurethane foams are known as described
in, for example, U.S. Pat. No. 3,978,266, U.S. Pat. No. 3,975,567
and EP 0 059 048. The aforementioned processes, however, have the
disadvantage that they require the use of reactive mixtures which
contain diisocyanates or corresponding NCO-functional prepolymers,
the handling of which is technically inconvenient and costly due to
the necessary appropriate protective measures associated with such
diisocyanates or NCO-functional prepolymers of these
diisocyanates.
[0004] One alternative to the above-described process which
utilizes diisocyanates or NCO-functional prepolymers, is a process
based on polyurethane dispersions (which are essentially free of
isocyanate groups) into which air is incorporated by vigorous
stirring in the presence of suitable (foam) additives. The
so-called mechanical polyurethane foams are obtained after drying
and curing. In connection with polyurethane wound dressing foams,
such are described in EP 0 235 949 and EP 0 246 723, with the foam
either having a self-adherent polymer added to it, or the foam
being applied to a film of a self-adherent polymer. In addition,
the examples in EP 0 235 949 and EP 0 246 723 require that
polyaziridines are used as crosslinkers. Polyaziridines are no
longer acceptable, however, because of their toxicity. Moreover,
crosslinking requires the use of high baking temperatures, with
these temperatures reported to be in the range from 100.degree. C.
to 170.degree. C. U.S. Pat. No. 4,655,210 describes the use of the
aforementioned mechanical foams for wound dressings which have a
specific construction made up of a backing, a foam and a skin
contact layer. The foams produced according to the processes
described in EP 0 235 949 and EP 0 246 723, moreover, have the
immense disadvantage that the foams obtained therein are only
minimally open-cell, which reduces the absorbance of physiological
saline and also the water or moisture vapor transmission rate.
[0005] The management of wounds having a complex topology or the
coverage of particularly deep wounds is difficult with
ready-to-use, industrially manufactured sheetlike polyurethane
wound dressing foams, since optimal covering of the wound surface
is generally not accomplished, thus retarding the healing process.
To achieve better covering of deep wounds, it has been proposed to
use granules of microporous polyurethanes instead of compact wound
dressings (see EP-A-0 171 268). However, this also does not achieve
optimal covering of the wound.
[0006] The application of a (flowable) polyurethane foam forming
composition which optimally conforms to the wound shape would
eliminate the disadvantages of sheetlike wound dressings. The two
processes described above, which utilize either
diisocyanates/NCO-functional polyurethane prepolymers or
polyurethane dispersions in combination with polyaziridines to
produce polyurethane foams, cannot be used for this. Reactive
polyurethane foam forming compositions which contain free
isocyanate groups cannot be applied directly to the skin, even
though this has been variously proposed (see, for example, WO
02/26848). Also, polyurethane dispersions which contain
polyaziridines as crosslinkers are not acceptable because this
crosslinker has properties which are not generally recognized as
safe by toxicologists.
[0007] An object of the present invention is to provide
polyurethane foams for wound management in which the foam
polyurethane foam forming composition is free of isocyanate groups.
The production of the polyurethane foam shall in principle also be
able to be carried out under ambient conditions, in which case the
resultant polyurethane foams, as well as having good mechanical
properties, shall have a high absorbence of physiological saline
and a high water and moisture vapor transmission rate. This
requires that the polyurethane foam have a certain open-cell
content. Moreover, the polyurethane foam forming composition shall
be suitable for direct application to the skin, for example, by
spraying or casting, in order that the wound may be optimally
covered with the polyurethane foam, which makes rapid drying
essential for this polyurethane foam forming composition.
SUMMARY OF THE INVENTION
[0008] It has now been found that polyurethane foam forming
compositions containing polyurethane dispersions and specific
cationic coagulants, both free of isocyanate groups, can be used to
produce at ambient conditions polyurethane foams having good
mechanical properties, a high absorbence of physiological saline
and a high water and moisture vapour transmission rate. The
polyurethane foams exhibit, at least to some extent, an open-cell
pore structure. The flowable polyurethane foam forming
compositions, moreover, can be applied directly to the skin by
spraying or casting.
[0009] The present invention accordingly provides a process for
producing polyurethane wound dressing foams made of a frothed and
dried polyurethane foam which comprises (I) at least one aqueous,
anionically hydrophilicized polyurethane dispersion and (II) at
least one cationic coagulant.
[0010] For purposes of the present invention, polyurethane wound
dressing foams are porous materials, preferably having at least
some open-cell content, which are made of polyurethanes. These
materials protect wounds against germs and environmental influences
like a sterile covering, and they have a fast and high absorbence
of physiological saline (i.e. more precisely wound fluid), a
suitable permeability for moisture to ensure a suitable wound
climate, and sufficient mechanical strength.
[0011] Suitable aqueous, anionically hydrophilicized polyurethane
dispersions to be used as component (I) in the polyurethane foam
forming compositions essential to the present invention comprise
the reaction product of: [0012] A) one or more
isocyanate-functional prepolymers which comprise the reaction
product of: [0013] A1) at least one organic polyisocyanate, [0014]
with [0015] A2) at least one polymeric polyol having a number
average molecular weight in the range from 400 to 8000 g/mol,
preferably in the range from 400 to 6000 g/mol and more preferably
in the range from 600 to 3000 g/mol, and an OH functionality in the
range from 1.5 to 6, preferably in the range from 1.8 to 3, more
preferably in the range from 1.9 to 2.1, [0016] and [0017] A3)
optionally, one or more hydroxyl-functional compounds having
molecular weights in the range from 62 to 399 g/mol, [0018] and
[0019] A4) optionally, one or more isocyanate-reactive, anionic or
potentially anionic and/or optionally nonionic hydrophilicizing
agents; [0020] with [0021] B) one or more compounds selected from
the group consisting of: [0022] B1) optionally, one or more
amino-functional compounds having molecular weights in the range
from 32 to 400 g/mol, [0023] and [0024] B2) one or more
isocyanate-reactive, preferably amino-functional, anionic or
potentially anionic hydrophilicizing agents,
[0025] in which the free NCO groups of A) said prepolymers are
wholly or partially reacted with isocyanate-reactive groups of B)
by chain extension, and in which the prepolymers are dispersed in
water before, during or after the reaction with component B), and
with any potential ionic groups present being converted into the
ionic form by partial or complete reaction with a neutralizing
agent.
[0026] To achieve anionic hydrophilicization, components A4) and/or
B2) contain hydrophilicizing agents that have at least one
NCO-reactive group such as amino, hydroxyl and/or thiol groups, and
additionally have --COO.sup.- or --SO.sub.3.sup.- or
--PO.sub.3.sup.2- as anionic groups or their wholly or partly
protonated acid forms as potential anionic groups.
DETAILED DESCRIPTION OF THE INVENTION
[0027] The preferred aqueous, anionic polyurethane dispersions used
as component (I) have a low degree of hydrophilic anionic groups.
More specifically, these preferably have from 0.1 to 15
milliequivalents of hydrophilic anionic groups per 100 g of solid
resin (i.e. solid polyurethane).
[0028] To achieve good sedimentation stability, the number average
particle size of the specific polyurethane dispersions is
preferably less than 750 nm and more preferably less than 500 nm.
As used herein, the number average particle size is determined by
laser correlation spectroscopy.
[0029] In the production of A) the isocyanate-functional prepolymer
from components A1) to A4), the molar ratio of components which
contain isocyanate groups to components which contain
isocyanate-reactive groups is in the range from 1.05 to 3.5,
preferably from 1.2 to 3.0 and more preferably in the range from
1.3 to 2.5, for the preparation of the NCO-functional prepolymers
used as component A).
[0030] The amino-functional compounds used as components B1) and
B2) are present in such an amount that the equivalent ratio of
isocyanate-reactive amino groups of these compounds in component B)
to the free isocyanate groups of the prepolymer A) is in the range
from 40 to 150%, preferably between 50 and 125% and more preferably
between 60 and 120%.
[0031] Suitable polyisocyanates to be used as component A1) include
the well-known aromatic, araliphatic, aliphatic and/or
cycloaliphatic polyisocyanates which have an NCO functionality of
.gtoreq.2.
[0032] Some examples of such suitable polyisocyanates are
1,4-butylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI),
isophorone diisocyanate (IPDI), 2,2,4- and/or
2,4,4-trimethylhexamethylene diisocyanate, the isomeric
bis(4,4'-isocyanatocyclohexyl)methanes or their mixtures of any
desired isomer content, 1,4-cyclohexylene diisocyanate,
1,4-phenylene diisocyanate, 2,4- and/or 2,6-toluene diisocyanate,
1,5-naphthalene diisocyanate, 2,2'- and/or 2,4'- and/or
4,4'-diphenylmethane diisocyanate, 1,3- and/or
1,4-bis-(2-isocyanatoprop-2-yl)benzene (TMXDI),
1,3-bis(isocyanatomethyl)benzene (XDI), and also alkyl
2,6-diisocyanatohexanoates (i.e. lysine diisocyanates) having
C.sub.1-C.sub.8-alkyl groups.
[0033] In addition to the aforementioned polyisocyanates, it is
also possible to use, proportionally, modified diisocyanates of
uretdione, isocyanurate, urethane, allophanate, biuret,
iminooxadiazinedione and/or oxadiazinetrione structure and also
non-modified polyisocyanate having more than 2 NCO groups per
molecule such as, for example, 4-isocyanatomethyl-1,8-octane
diisocyanate (i.e. nonane triisocyanate) or triphenylmethane
4,4',4''-triisocyanate.
[0034] Preferably, the polyisocyanates or polyisocyanate mixtures
of the aforementioned kind have exclusively aliphatically and/or
cycloaliphatically attached isocyanate groups and an average NCO
functionality in the range from 2 to 4, more preferably in the
range from 2 to 2.6 and most preferably in the range from 2 to 2.4
for the mixture.
[0035] It is particularly preferred for component A1) to comprise
1,6-hexamethylene diisocyanate, isophorone diisocyanate, the
isomeric bis(4,4'-isocyanatocyclo-hexyl)methanes or also mixtures
thereof.
[0036] Component A2) comprises at least one polymeric polyol having
a number average molecular weight M.sub.n in the range from 400 to
8000 g/mol, preferably from 400 to 6000 g/mol and more preferably
from 600 to 3000 g/mol. These polymeric polyols preferably have an
OH functionality in the range from 1.5 to 6, more preferably from
1.8 to 3 and most preferably from 1.9 to 2.1.
[0037] Such polymeric polyols are the well-known polyester polyols,
polyacrylate polyols, polyurethane polyols, polycarbonate polyols,
polyether polyols, polyester polyacrylate polyols, polyurethane
polyacrylate polyols, polyurethane polyester polyols, polyurethane
polyether polyols, polyurethane polycarbonate polyols and polyester
polycarbonate polyols which are commonly used in polyurethane
coating technology. These can be used either individually or in any
desired mixtures with one another as component A2).
[0038] These polyester polyols are the well-known polycondensates
formed from di- and also optionally tri- and tetraols with di- and
also optionally tri- and tetracarboxylic acids or hydroxy
carboxylic acids or lactones. Instead of the free polycarboxylic
acids, it is also possible to use the corresponding polycarboxylic
anhydrides or corresponding polycarboxylic esters of lower alcohols
for preparing the polyesters.
[0039] Examples of suitable diols are ethylene glycol, butylene
glycol, diethylene glycol, triethylene glycol, polyalkylene glycols
such as polyethylene glycol, as well as 1,2-propanediol,
1,3-propanediol, butanediol(1,3), butanediol(1,4), hexanediol(1,6)
and isomers thereof, neopentyl glycol or neopentyl glycol
hydroxypivalate. Preferred diols include hexanediol(1,6) and
isomers thereof, neopentyl glycol and neopentyl glycol
hydroxypivalate. In addition to these, it is also possible to use
polyols such as trimethylolpropane, glycerol, erythritol,
pentaerythritol, trimethylolbenzene or trishydroxyethyl
isocyanurate.
[0040] Suitable dicarboxylic acids include, for example, phthalic
acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid,
hexahydrophthalic acid, cyclohexanedicarboxylic acid, adipic acid,
azelaic acid, sebacic acid, glutaric acid, tetrachlorophthalic
acid, maleic acid, fumaric acid, itaconic acid, malonic acid,
suberic acid, 2-methylsuccinic acid, 3,3-diethyl glutaric acid
and/or 2,2-dimethylsuccinic acid. The corresponding anhydrides can
also be used as a source of an acid.
[0041] When the average functionality of the polyol to be
esterified is greater than 2, monocarboxylic acids, such as benzoic
acid and hexanecarboxylic acid, can be used as well.
[0042] Preferred carboxylic acids are aliphatic or aromatic acids
of the aforementioned kind. Adipic acid, isophthalic acid and
optionally trimellitic acid are particularly preferred.
[0043] Hydroxy carboxylic acids which are useful reactants in the
preparation of a polyester polyol having terminal hydroxyl groups
include, for example, hydroxycaproic acid, hydroxybutyric acid,
hydroxydecanoic acid, hydroxystearic acid and the like. Suitable
lactones include, for example, caprolactone, butyrolactone and
homologues. Caprolactone is preferred.
[0044] Likewise, component A2) may comprise at least one
hydroxyl-containing polycarbonate, preferably at least one
polycarbonate diol, which have a number average molecular weight
M.sub.n in the range from 400 to 8000 g/mol and preferably in the
range from 600 to 3000 g/mol. These are obtainable by the reaction
of carbonic acid derivatives, such as diphenyl carbonate, dimethyl
carbonate or phosgene, with polyols, preferably diols.
[0045] Examples of such diols are ethylene glycol, 1,2-propanediol,
1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol,
1,8-octanediol, neopentyl glycol, 1,4-bishydroxymethylcyclohexane,
2-methyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol,
dipropylene glycol, polypropylene glycols, dibutylene glycol,
polybutylene glycols, bisphenol A and lactone-modified diols of the
aforementioned kind.
[0046] The polycarbonate diol preferably contains 40% to 100% by
weight of hexanediol, with preference being given to 1,6-hexanediol
and/or hexanediol derivatives. Such hexanediol derivatives are
based on hexanediol and have ester or ether groups as well as
terminal OH groups. Such derivatives are obtainable by the reaction
of hexanediol with excess caprolactone, or by etherification of
hexanediol with itself to form di- or trihexylene glycol.
[0047] In lieu of or in addition to pure polycarbonate diols,
polyether-polycarbonate diols are also suitable for use as A2) a
polymeric polyol.
[0048] Hydroxyl-containing polycarbonates preferably have a linear
construction.
[0049] Component A2) may likewise comprise at least one polyether
polyols.
[0050] Suitable polyether polyols include, for example, the
well-known polytetramethylene glycol polyethers which are
obtainable by polymerization of tetrahydrofuran by means of
cationic ring opening. Such polyether polyols are known and
described in various texts dealing with polyurethane chemistry.
[0051] Suitable polyether polyols likewise include the well-known
addition products of styrene oxide, ethylene oxide, propylene
oxide, butylene oxides and/or epichlorohydrin onto di- or
polyfunctional starter molecules. The polyether polyols based on
the at least proportional addition of ethylene oxide onto di- or
polyfunctional starter molecules can also be used as component A4)
(i.e. nonionic hydrophilicizing agents).
[0052] Suitable starter molecules for the preparation of polyether
polyols include all known hydroxyl-group and/or amine-group
containing compounds such as, for example, water, butyl diglycol,
glycerol, diethylene glycol, trimethylolpropane, propylene glycol,
sorbitol, ethylenediamine, triethanolamine, 1,4-butanediol. These
starter molecules contain at least one (and preferably more than
one) isocyanate-reactive group. Preferred starter molecules are
water, ethylene glycol, propylene glycol, 1,4-butanediol,
diethylene glycol and butyl diglycol.
[0053] In a particularly preferred embodiment of (I) the
polyurethane dispersions, component A2) comprises a mixture of at
least one polycarbonate polyol and at least one polytetramethylene
glycol polyol, with the proportion of polycarbonate polyols in this
mixture being in the range from 20% to 80% by weight and the
proportion of polytetramethylene glycol polyols in this mixture
being in the range from 80% to 20% by weight, with the sum of the
%'s by weight for the polycarbonate polyols and polytetramethylene
glycol polyols totals 100%. Preference is given to a proportion of
30% to 75% by weight for polytetramethylene glycol polyols and to a
proportion of 25% to 70% by weight for polycarbonate polyols.
Particular preference is given to a proportion of 35% to 70% by
weight for polytetramethylene glycol polyols and to a proportion of
30% to 65% by weight for polycarbonate polyols. In addition, the
proportion of component A2) which is accounted for by the sum total
of the polycarbonate and polytetramethylene glycol polyether
polyols is at least 50% by weight, preferably 60% by weight, and
more preferably at least 70% by weight, based on 100% by weight of
A2).
[0054] Suitable compounds to be used as component A3) have
molecular weights of 62 to 400 g/mol.
[0055] Component A3) may utilize polyols of the specified molecular
weight range which contain up to 20 carbon atoms, such as ethylene
glycol, diethylene glycol, triethylene glycol, 1,2-propanediol,
1,3-propanediol, 1,4-butanediol, 1,3-butylene glycol,
cyclohexanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol,
neopentyl glycol, hydroquinone dihydroxyethyl ether, bisphenol A
(2,2-bis(4-hydroxyphenyl)-propane), hydrogenated bisphenol A,
(2,2-bis(4-hydroxycyclohexyl)propane), trimethylolpropane,
glycerol, pentaerythritol and also any desired mixtures thereof
with one another.
[0056] Also suitable are ester diols of the specified molecular
weight range such as, for example,
.alpha.-hydroxybutyl-.epsilon.-hydroxycaproic acid ester,
.omega.-hydroxyhexyl-.gamma.-hydroxybutyric acid ester,
.beta.-hydroxyethyl adipate or bis(.beta.-hydroxyethyl)
terephthalate.
[0057] Component A3) may additionally comprise monofunctional
isocyanate-reactive hydroxyl-containing compounds. Examples of such
monofunctional compounds are ethanol, n-butanol, ethylene glycol
monobutyl ether, diethylene glycol monomethyl ether, ethylene
glycol monobutyl ether, diethylene glycol monobutyl ether,
propylene glycol monomethyl ether, dipropylene glycol monomethyl
ether, tripropylene glycol monomethyl ether, dipropylene glycol
monopropyl ether, propylene glycol monobutyl ether, dipropylene
glycol monobutyl ether, tripropylene glycol monobutyl ether,
2-ethylhexanol, 1-octanol, 1-dodecanol, 1-hexadecanol, etc.
[0058] Preferred compounds to be used as component A3) are
1,6-hexanediol, 1,4-butanediol, neopentyl glycol and
trimethylolpropane.
[0059] Component A4) herein which is also optional, comprises one
or more isocyanate-reactive, anionic or potentially anionic and
optionally nonionic hydrophilicizing agents. Thus, the suitable
isocyanate-reactive hydrophilicizing agents herein additionally
contain one or more of anionic groups, potentially anionic groups
and/or nonionic groups.
[0060] Suitable anionically or potentially anionically
hydrophilicizing compounds to be used as component A4) are any
compounds which have at least one isocyanate-reactive group such as
a hydroxyl group and also at least one other type of functionality,
i.e. a functionality that is not an isocyanate-reactive group. Such
functionalities include for example --COO.sup.-M.sup.+,
--SO.sub.3.sup.-M.sup.+, and/or --PO(O.sup.-M.sup.+).sub.2 in which
M.sup.+ represents, for example, a metal cation, H.sup.+,
NH.sub.4.sup.+, NHR.sub.3.sup.+, in which each R independently
represents a C.sub.1-C.sub.12-alkyl group, a
C.sub.5-C.sub.6-cycloalkyl group or a C.sub.2-C.sub.4-hydroxyalkyl
group. This functionality enters a pH-dependent dissociative
equilbrium on interaction with aqueous media, and can thereby have
a negative or neutral charge. Some useful anionically or
potentially anionically hydrophilicizing compounds include, for
example, mono- and dihydroxy carboxylic acids, mono- and dihydroxy
sulfonic acids and also mono- and dihydroxy phosphonic acids and
their salts. Specific examples of such anionic or potentially
anionic hydrophilicizing agents are dimethylolpropionic acid,
dimethylolbutyric acid, hydroxypivalic acid, malic acid, citric
acid, glycolic acid, lactic acid and the propoxylated adduct formed
from 2-butenediol and NaHSO.sub.3 and which is described in, for
example, U.S. Pat. No. 4,108,814 (which is believed to correspond
to DE-A 2 446 440, see page 5-9, formula I-III therein), the
disclosure of which is hereby incorporated by reference. Preferred
anionic or potentially anionic hydrophilicizing agents for
component A4) are those of the aforementioned kind that have
carboxylate or carboxyl groups and/or sulfonate groups.
[0061] Particularly preferred anionic or potentially anionic
hydrophilicizing agents are those that contain carboxylate or
carboxyl groups as ionic or potentially ionic groups, such as
dimethylolpropionic acid, dimethylolbutyric acid and hydroxypivalic
acid and salts thereof.
[0062] Useful nonionically hydrophilicizing compounds which are
suitable for use as component A4) include, for example,
polyoxyalkylene ethers which contain at least one hydroxyl or amino
group, and preferably at least one hydroxyl group.
[0063] Examples of these are the monohydroxyl-functional
polyalkylene oxide polyether alcohols which contain on average 5 to
70 and preferably 7 to 55 ethylene oxide units per molecule, and
are obtainable in a conventional manner by alkoxylation of suitable
starter molecules. Such a process is described in, for example,
Ullmanns Encyclopadie der technischen Chemie, 4th edition, volume
19, Verlag Chemie, Weinheim pages 31-38.
[0064] Obviously such compounds can not be simultaneously be used
as component A2) and A4). Thus, if component A2) comprises a
polyether polyol prepared by addition of ethylene oxide onto
suitable starter molecules, then component A4) is another type of
hydrophilicizing agent. Similarly, if component A4) comprises a
polyethylene oxide ether then component A2) is another type of
polymeric polyol. In this manner, components A2) and a4) are
mutually exclusive.
[0065] These compounds are either pure polyethylene oxide ethers or
mixed polyalkylene oxide ethers, containing at least 30 mol % and
preferably at least 40 mol % of ethylene oxide units, based on all
alkylene oxide units present.
[0066] Preferred polyethylene oxide ethers of the aforementioned
kind are monofunctional mixed polyalkylene oxide polyethers having
40 to 100 mol % of ethylene oxide units and 0 to 60 mol % of
propylene oxide units.
[0067] Preferred nonionically hydrophilicizing compounds for
component A4) include those of the aforementioned kind that are
block (co)polymers prepared by blockwise addition of alkylene
oxides onto suitable starters.
[0068] Suitable starter molecules for such nonionic
hydrophilicizing agents include saturated monoalcohols such as
methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol,
sec-butanol, the isomeric pentanols, hexanols, octanols and
nonanols, n-decanol, n-dodecanol, n-tetradecanol, n-hexadecanol,
n-octadecanol, cyclohexanol, the isomeric methylcyclohexanols or
hydroxymethylcyclohexane, 3-ethyl-3-hydroxymethyloxetane or
tetrahydrofurfuryl alcohol, diethylene glycol monoalkyl ethers such
as, for example diethylene glycol monobutyl ether, unsaturated
alcohols such as allyl alcohol, 1,1-dimethylallyl alcohol or oleic
alcohol, aromatic alcohols such as phenol, the isomeric cresols or
methoxy-phenols, araliphatic alcohols such as benzyl alcohol, anis
alcohol or cinnamyl alcohol, secondary monoamines such as
dimethylamine, diethylamine, dipropylamine, diisopropylamine,
dibutylamine, bis(2-ethylhexyl)amine, N-methylcyclohexylamine,
N-ethylcyclohexylamine or dicyclohexylamine and also heterocyclic
secondary amines such as morpholine, pyrrolidine, piperidine or 1H
pyrazole. Preferred starter molecules are saturated monoalcohols of
the aforementioned kind. Particular preference is given to using
diethylene glycol monobutyl ether or n-butanol as starter
molecules.
[0069] The useful alkylene oxides for the alkoxylation reaction
are, in particular, ethylene oxide and propylene oxide, which can
be used in any desired order or else in admixture in the
alkoxylation reaction.
[0070] Suitable compounds to be used as component B1) in accordance
with the present invention include di- or polyamines such as
1,2-ethylenediamine, 1,2-diamino-propane, 1,3-diaminopropane,
1,4-diaminobutane, 1,6-diaminohexane, isophoronediamine, isomeric
mixtures of 2,2,4- and 2,4,4-trimethyl-hexamethylenediamine,
2-methylpentamethylenediamine, diethylenetriamine, triaminononane,
1,3-xylylenediamine, 1,4-xylylenediamine,
.alpha.,.alpha.,.alpha.',.alpha.'-tetramethyl-1,3- and
-1,4-xylylenediamine and 4,4-diaminodicyclohexylmethane and/or
dimethylethylenediamine. It is also possible but less preferable to
use hydrazine or also hydrazides such as adipohydrazide.
[0071] Component B1) can also include compounds which, in addition
to a primary amino group, also have one or more secondary amino
groups or which also have one or more OH groups in additional to an
amino group (either primary or secondary). Examples thereof are
primary/secondary amines, such as diethanol-amine,
3-amino-1-methylaminopropane, 3-amino-1-ethylaminopropane,
3-amino-1-cyclohexylaminopropane, 3-amino-1-methylaminobutane,
alkanolamines such as N-aminoethylethanolamine, ethanolamine,
3-aminopropanol, neopentanol-amine, etc.
[0072] In addition, component B1) can comprise monofunctional
isocyanate-reactive amine compounds, for example, methylamine,
ethylamine, propylamine, butylamine, octylamine, laurylamine,
stearylamine, isononyloxypropylamine, dimethylamine, diethylamine,
dipropylamine, dibutylamine, N-methylaminopropylamine,
diethyl(methyl)aminopropylamine, morpholine, piperidine, or
suitable substituted derivatives thereof, amide-amines formed from
diprimary amines and monocarboxylic acids, monoketimes of diprimary
amines, primary/tertiary amines, such as
N,N-dimethylaminopropylamine.
[0073] Preferred compounds for component B1) are
1,2-ethylenediamine, 1,4-diaminobutane and isophoronediamine.
[0074] Suitable anionically or potentially anionically
hydrophilicizing compound to be used as component B2) include any
compound which has at least one isocyanate-reactive group,
preferably an amino group, and also at least one type of
functionality (i.e. a functionality that is not an
isocyanate-reactive group) such as, for example,
--COO.sup.-M.sup.+, --SO.sub.3.sup.-M.sup.+,
--PO(O.sup.-M.sup.+).sub.2 in which M.sup.+ represents, for
example, a metal cation, H.sup.+, NH.sub.4.sup.+, or
NHR.sub.3.sup.+, in which each R independently represents a
C.sub.1-C.sub.12-alkyl group, a C.sub.5-C.sub.6-cycloalkyl group or
a C.sub.2-C.sub.4-hydroxyalkyl group. This functionality enters a
pH dependent dissociative equilibrium upon interaction with aqueous
media, and can thereby can have a negative or neutral charge.
[0075] Some suitable anionically or potentially anionically
hydrophilicizing compounds for the present invention are mono- and
diamino carboxylic acids, mono- and diamino sulfonic acids and also
mono- and diamino phosphonic acids and their salts. Examples of
such anionic or potentially anionic hydrophilicizing agents are
N-(2-aminoethyl)-.beta.-alanine,
2-(2-aminoethylamino)ethanesulfonic acid,
ethylenediaminepropylsulfonic acid, ethylenediaminebutylsulfonic
acid, 1,2- or 1,3-propylenediamine-.beta.-ethylsulfonic acid,
glycine, alanine, taurine, lysine, 3,5-diaminobenzoic acid and the
addition product of IPDA and acrylic acid. Such addition products
of IPDA and acrylic acid are described in, for example, EP-A 0 916
647 (Example 1) which is believed to correspond to CA 2,253,119,
the disclosures of which are hereby incorporated by reference. It
is also possible to use cyclohexylaminopropanesulfonic acid (CAPS)
as described in WO-A 01/88006 which is believed to correspond to
U.S. Pat. No. 6,767,958, the disclosure of which is hereby
incorporated by reference, as anionic or potentially anionic
hydrophilicizing agent.
[0076] Preferred anionic or potentially anionic hydrophilicizing
agents for component B2) are those of the aforementioned kind that
have carboxylate or carboxyl groups and/or sulfonate groups, such
as the salts of N-(2-aminoethyl)-.beta.-alanine, of
2-(2-aminoethylamino)ethanesulfonic acid or of the addition product
of IPDA and acrylic acid (see Example 1 of EP-A 0 916 647).
[0077] Mixtures of anionic or potentially anionic hydrophilicizing
agents and nonionic hydrophilicizing agents can also be used.
[0078] A preferred embodiment for producing the specific
polyurethane dispersions comprises components A1) to A4) and B1) to
B2) in the following amounts, with the sum of the individual
amounts always adding up to 100% by weight:
[0079] 5% to 40% by weight of component A1),
[0080] 55% to 90% by weight of component A2),
[0081] 0.5% to 20% by weight of the sum total of components A3) and
B1), and
[0082] 0.1 % to 25% by weight of the sum total of the components
A4) and B2), wherein from 0.1% to 5% by weight of anionic or
potentially anionic hydrophilicizing agents from components A4)
and/or B2) are present, based on 100% by weight of components A1)
to A4) and B1) to B2).
[0083] A particularly preferred embodiment for producing the
specific polyurethane dispersions comprises components A1) to A4)
and B1) to B2) in the following amounts, with the sum of the
individual amounts always adding up to 100% by weight:
[0084] 5% to 35% by weight of component A1),
[0085] 60% to 90% by weight of A2),
[0086] 0.5% to 15% by weight of the sum total of components A3) and
B1), and
[0087] 0.1% to 15% by weight of the sum total of the components A4)
and B2), wherein from 0.2% to 4% by weight of anionic or
potentially anionic hydrophilicizing agents from components A4)
and/or B2) are present, based on 100% by weight of components A1)
to A4) and B1) to B2).
[0088] A very particularly preferred embodiment for producing the
specific polyurethane dispersions comprises components A1) to A4)
and B1) to B2) in the following amounts, with the sum of the
individual amounts always adding up to 100% by weight:
[0089] 10% to 30% by weight of component A1),
[0090] 65% to 85% by weight of A2),
[0091] 0.5% to 14% by weight of the sum total of components A3) and
B1), and
[0092] 0.1% to 13.5% by weight of the sum total of the components
A4) and B2), wherein from 0.5% to 3.0% by weight of anionic or
potentially anionic hydrophilicizing agents from components A4)
and/or B2) are present, based on 100% by weight of components A1)
to A4) and B1) to B2).
[0093] The production of (I) the anionically hydrophilicized
polyurethane dispersions (I) can be carried out in one or more
stages in homogeneous phase or, in the case of a multistage
reaction, partly in disperse phase. After completely or partially
conducted polyaddition of components A1) to A4), a dispersing,
emulsifying or dissolving step is carried out. This is followed, if
appropriate, by a further polyaddition or modification in the
disperse phase.
[0094] Any of the known prior art processes can be used. Specific
examples of such processes being the prepolymer mixing process, the
acetone process or the melt dispersing process. The acetone process
is preferred.
[0095] Production by the acetone process typically involves the
constituents A2) to A4) and the polyisocyanate component A1) being
wholly or partly introduced as an initial charge to produce an
isocyanate-functional polyurethane prepolymer, and optionally
diluted with a water-miscible but isocyanate-inert solvent and
heated to temperatures in the range from 50 to 120.degree. C. The
rate of the isocyanate addition reaction can be increased using the
catalysts known in polyurethane chemistry.
[0096] Useful solvents include the customary aliphatic,
keto-functional solvents such as acetone, 2-butanone, etc., which
can be added not just at the start of the production process but
also later, and optionally in portions. Acetone and 2-butanone are
preferred.
[0097] Other solvents such as xylene, toluene, cyclohexane, butyl
acetate, methoxypropyl acetate, N-methylpyrrolidone,
N-ethylpyrrolidone, solvents having ether or ester units can
additionally be used or wholly or partly distilled off, or in the
case of N-methylpyrrolidone and/or N-ethylpyrrolidone, remain
completely in the dispersion. Preference is however given to not
using any other solvents apart from the customary aliphatic,
keto-functional solvents.
[0098] Subsequently, any constituents of A1) to A4) not added at
the start of the reaction are added.
[0099] In the production of the A) the isocyanate-functional
prepolymer from components A1) to A4), the molar ratio of
components which contain isocyanate groups to components which
contain isocyanate-reactive groups is in the range from 1.05 to
3.5, preferably in the range from 1.2 to 3.0 and more preferably in
the range from 1.3 to 2.5.
[0100] The reaction of components A1) to A4) to form A) the
prepolymer is effected partially or completely, but preferably
completely. Isocyanate-functional prepolymers which contain free
isocyanate groups are obtained in this way, without a solvent or in
solution.
[0101] The neutralizing step to effect either partial or complete
conversion of potentially anionic groups into anionic groups
utilizes bases such as tertiary amines such as, for example,
trialkylamines having 1 to 12 and preferably 1 to 6 carbon atoms
and more preferably 2 to 3 carbon atoms in every alkyl radical or
alkali metal bases such as the corresponding hydroxides.
[0102] Examples thereof are trimethylamine, triethylamine,
methyldiethylamine, tripropylamine, N-methylmorpholine,
methyldiisopropylamine, ethyldiisopropylamine and
diisopropylethylamine. The alkyl radicals may also contain, for
example, hydroxyl groups, such as in the case of the
dialkylmonoalkanol-, alkyldialkanol- and trialkanolamines. Useful
neutralizing agents further include if appropriate inorganic bases,
such as aqueous ammonia solution, sodium hydroxide or potassium
hydroxide.
[0103] Preference is given to bases such as ammonia, triethylamine,
triethanolamine, dimethylethanolamine or diisopropylethylamine, and
also sodium hydroxide and potassium hydroxide. It is particularly
preferred that the base be selected from the group consisting of
sodium hydroxide and potassium hydroxide.
[0104] The bases are employed in an amount which is between 50 and
125 mol %, and preferably between 70 and 100 mol %, based on the
quantity of substance containing the acid groups to be neutralized.
Neutralization can also be effected at the same time as the
dispersing step, by including the neutralizing agent in the water
of dispersion.
[0105] Subsequently, in a further process step, if this has not
already been done or has only partially been done, the resultant
prepolymer is dissolved with the aid of aliphatic ketones such as
acetone or 2-butanone.
[0106] In the chain extension of the isocyanate-functional
prepolymers A) with component B), the NH.sub.2-- and/or
NH-functional components are reacted by chain extension, either
partially or completely, with the remaining isocyanate groups of
the prepolymer. Preferably, the chain extension/termination is
carried out before dispersion of the prepolymers in water.
[0107] Chain termination is typically carried out using component
B1) one or more amines having an isocyanate-reactive group such as
methylamine, ethylamine, propylamine, butylamine, octylamine,
laurylamine, stearylamine, isononyloxypropylamine, dimethylamine,
diethylamine, dipropylamine, dibutylamine,
N-methylaminopropylamine, diethyl(methyl)aminopropylamine,
morpholine, piperidine or suitable substituted derivatives thereof,
amide-amines formed from diprimary amines and monocarboxylic acids,
monoketimes of diprimary amines, primary/tertiary amines, such as
N,N-dimethylaminopropylamine.
[0108] When partial or complete chain extension is carried out
using component B2) one or more anionic or potentially anionic
hydrophilicizing agents as described hereinabove with NH.sub.2 or
NH groups, it is preferred that chain extension of A) the
isocyanate-functional prepolymers is carried out before dispersion
of the prepolymers in water.
[0109] The aminic components B1) and B2) can optionally be used in
water- or solvent-diluted form in the process of the present
invention. These components may be used either individually or in
mixtures, with any order of addition being possible in
principle.
[0110] When water or organic solvent is used as a diluent, the
diluent content of component B) is preferably in the range from 70%
to 95% by weight, based on 100% by weight of component B).
[0111] Dispersion of the prepolymer is preferably carried out
following chain extension. For dispersion, the dissolved and
chain-extended polyurethane polymer is either introduced into the
dispersing water, if appropriate by substantial shearing, such as
vigorous stirring for example, or conversely the dispersing water
is stirred into the chain-extended polyurethane polymer solutions.
It is preferable to add the water to the dissolved chain-extended
polyurethane polymer.
[0112] Any solvent that is still present in the dispersions after
the dispersing step is then typically removed by distillation.
Removal during the dispersing step is likewise possible.
[0113] The residual level of organic solvents in (I) the
polyurethane dispersions is typically less than 1.0% by weight and
preferably less than 0.5% by weight, based on 100% by weight of the
dispersion.
[0114] The pH of (I) the polyurethane dispersions which are
essential to the present invention is typically less than 9.0,
preferably less than 8.5, more preferably less than 8.0 and most
preferably is in the range from 6.0 to 7.5.
[0115] The solids content of (I) the polyurethane dispersions is
preferably in the range from 40% to 70%, more preferably in the
range from 50% to 65%, most preferably in the range from 55% to 65%
and especially preferably from 60% to 65% by weight (based on 100%
by weight of the dispersions).
[0116] Component (II) of the polyurethane foam forming compositions
herein comprise at least one coagulant. Suitable coagulants can be
any organic compound which contains at least 2 cationic groups,
preferably any known cationic flocculating and/or precipitating
agent of the prior art. Such coagulants include, for example, a
cationic homo- or copolymer of a salt of
poly[2-(N,N,N-trimethylamino)ethyl acrylate], of polyethyleneimine,
of poly[N-(dimethylaminomethyl)acrylamide], of a substituted
acrylamide, of a substituted methacrylamide, of N-vinylformamide,
of N-vinylacetamide, of N-vinylimidazole, of 2-vinylpyridine or of
4-vinylpyridine.
[0117] Preferred cationic coagulants to be used as component (II)
are acrylamide copolymers which comprise structural units which
correspond to the general formula (2), and more preferably which
comprise structural units which correspond to both of the general
formulae (1) and (2): ##STR1##
[0118] wherein: [0119] R: represents C.dbd.O,
--COO(CH.sub.2).sub.2-- or --COO(CH.sub.2).sub.3--, and [0120]
X.sup.-: represents a halide ion, preferably chloride.
[0121] These coagulants for component (II) preferably have number
average molecular weights in the range from 500,000 to 50,000,000
g/mol.
[0122] Coagulants based on acrylamide copolymers to be used as
component (II) are commercially available, for example, under the
trade name of Praestol.RTM. (from Degussa Stockhausen, Krefeld,
Germany) as flocculants for activated sludges. Preferred coagulants
of the Praestol.RTM. type are Praestol.RTM. K111L, K122L, K133L, BC
270L, K 144L, K 166L, BC 55L, 185K, 187K, 190K, K222L, K232L,
K233L, K234L, K255L, K332L, K 333L, K 334L, E 125, E 150 and also
mixtures thereof. Praestol.RTM. 185K, 187K and 190K and also
mixtures thereof are more preferred coagulating agents.
[0123] The residual levels of monomers, in particular of acrylate
and/or of acrylamide monomers, in the coagulants are preferably
less than 1% by weight, more preferably less than 0.5% by weight
and most preferably less than 0.025% by weight (based on 100% by
weight of the coagulant).
[0124] The coagulants can be used in solid form or as aqueous
solutions or dispersions. It is preferred to use coagulants as
aqueous dispersions or solutions.
[0125] In addition to (I) the polyurethane dispersions, and (II)
the coagulants, it is also possible that these polyurethane foam
forming compositions comprise (III) one or more auxiliary agents
and/or additive materials.
[0126] Examples of suitable auxiliary agents and additive materials
to be used as component (III) herein are foam auxiliaries such as
foam formers and stabilizers, thickeners or thixotroping agents,
antioxidants, light stabilizers, emulsifiers, plasticizers,
pigments, fillers and/or flow control agents.
[0127] It is preferred that foam auxiliaries such as foam formers
and stabilizers are included as (III) auxiliary agents and/or
additive materials. Useful foam auxiliaries include, for example,
commercially available compounds such as fatty acid amides,
sulfosuccinamides, hydrocarbyl sulfates or sulfonates or fatty acid
salts, in which case the lipophilic radical preferably contains
from 12 to 24 carbon atoms, as well as alkylpolyglycosides, which
are in principle known in prior art and which can be produced by
reaction of long chain monoalcohols with 4 to 22 C atoms in the
alkyl chain, with mono-, di- and polysaccharides, respectively (see
for example Kirk-Othmer, Encyclopedia of Chemical Technology, John
Wiley & Sons, Vol. 24, S. 29)
[0128] Preferred foam auxiliaries are sulfosuccinamides,
alkanesulfonates or alkyl sulfates having from 12 to 22 carbon
atoms in the hydrocarbyl radical, alkylbenzenesulfonates or
alkylbenzene sulfates having from 14 to 24 carbon atoms in the
hydrocarbyl radical, and/or fatty acid amides or fatty acid salts
having from 12 to 24 carbon atoms in the hydrocarbyl radical, as
well as alkylpolyglycosides.
[0129] Such fatty acid amides are preferably based on mono- or
di-(C.sub.2-C.sub.3-alkanol)-amines. The fatty acid salts may be,
for example, alkali metal salts, amine salts or unsubstituted
ammonium salts.
[0130] Such fatty acid derivatives are typically based on fatty
acids such as lauric acid, myristic acid, palmitic acid, oleic
acid, stearic acid, ricinoleic acid, behenic acid or arachidic
acid, coco fatty acid, tallow fatty acid, soya fatty acid and their
hydrogenation products.
[0131] Particularly preferred foam auxiliaries are mixtures of
sulfosuccinamides and ammonium stearates. These mixtures preferably
comprise from 20% to 60% by weight and more preferably from 30% to
50% by weight of ammonium stearates, and preferably 80% to 40% by
weight, and more preferably 70% to 50% by weight of
sulfosuccinamides, in which the sum of the %'s by weight of the
ammonium stearates and sulfosuccinamides totals 100% by weight of
the mixture.
[0132] Commercially available thickeners can be used. Suitable
thickeners include derivatives of dextrin, of starch or of
cellulose such as, for example, cellulose ethers or
hydroxyethylcellulose, organic wholly synthetic thickeners based on
polyacrylic acids, polyvinylpyrrolidones, polymethacrylic compounds
or polyurethanes (associative thickeners) and also inorganic
thickeners, such as bentonites or silicas.
[0133] In principle, although not preferred, the polyurethane foam
forming compositions which are essential to the present invention
can also contain crosslinkers such as unblocked polyisocyanates,
amide- and amine-formaldehyde resins, phenolic resins, aldehydic
and ketonic resins, examples being phenol-formaldehyde resins,
resols, furan resins, urea resins, carbamic ester resins, triazine
resins, melamine resins, benzoguanamine resins, cyanamide resins or
aniline resins.
[0134] The polyurethane foam forming compositions which are
essential to the present invention typically contain, based on dry
substance, (I) from 80 to 99.5 parts by weight of one or more
aqueous anionically hydrophilicized dispersions, (II) from 0.5 to 5
parts by weight of one or more cationic coagulants, and optionally,
(III) one or more auxiliary agents and/or additives which comprise
from 0 to 10 parts by weight of one or more foam auxiliaries, from
0 to 10 parts by weight of one or more crosslinkers and from 0 to
10 parts by weight of one or more thickeners.
[0135] It is preferred that the polyurethane foam forming
compositions which are essential to the present invention contain,
based on dry substance, (I) from 85 to 97 parts by weight of one or
more dispersions, (II) from 0.75 to 4 parts by weight of one or
more cationic coagulants, and (III) one or more auxiliary agents
and/or additives which comprise from 0.5 to 6 parts by weight of a
foam auxiliary, from 0 to 5 parts by weight of a crosslinker, and
from 0 to 5 parts by weight of thickener.
[0136] More preferably, the polyurethane foam forming compositions
which are essential to the present invention contain, based on dry
substance, (I) from 89 to 97 parts by weight of one or more
dispersions, (II) from 0.75 to 3 parts by weight of one or more
cationic coagulants, and (III) one or more auxiliary agents and/or
additives which comprise from 0.5 to 5 parts by weight of a foam
auxiliary, from 0 to 4 parts by weight of a crosslinker and from 0
to 4 parts by weight of thickener.
[0137] In addition to components (I) and (II), and optionally
(III), other aqueous binders can also be present in the
polyurethane foam forming compositions of the present invention.
Such aqueous binders can be constructed, for example, of polyester,
polyacrylate, polyepoxy or other polyurethane polymers. Similarly,
the combination with radiation-curable binders such as described
in, for example, U.S. Pat. No. 5,684,081, the disclosure of which
is hereby incorporated by reference (and which is believed to
correspond to EP-A-0 753 531), is also possible. It is also
possible to employ other anionic or nonionic dispersions such as,
for example, polyvinyl acetate, polyethylene, polystyrene,
polybutadiene, polyvinyl chloride, polyacrylate and copolymer
dispersions.
[0138] Frothing in the process of the present invention is
accomplished by mechanical stirring of the polyurethane foam
forming composition at high speeds of rotation by shaking or by
decompressing a blowing gas.
[0139] Mechanical frothing can be effected using any desired
mechanical stirring, mixing and/or dispersing techniques. Air is
generally introduced, but nitrogen and other gases can also be used
for this purpose.
[0140] The polyurethane foam thus obtained is, in the course of
frothing or immediately thereafter, applied to a substrate or
introduced into a mold and dried.
[0141] Application of the polyurethane foam to a substrate can be,
for example, by casting or blade coating, but other conventional
techniques are also possible. Multilayered application with
intervening drying steps is also possible in principle.
[0142] A satisfactory drying rate for the polyurethane foams is
observed at a temperature as low as 20.degree. C., so that drying
on injured human or animal tissue presents no problem. However,
temperatures above 30.degree. C. are preferably used for more rapid
drying and fixing of the foams. Drying temperatures should not,
however, exceed 200.degree. C., preferably 150.degree. C. and more
preferably 130.degree. C., since undesirable yellowing of the foams
can otherwise occur, inter alia. Drying of the polyurethane foams
in two or more stages is also possible.
[0143] Drying is generally effected using conventional heating and
drying apparatus, such as (circulating air) drying cabinets, hot
air or IR radiators. Drying by leading (or passing) the coated
substrate over heated surfaces, for example rolls, is also
possible.
[0144] Application and drying of the polyurethane foams can each be
carried out batchwise or continuously, but the entirely continuous
process is preferred.
[0145] Useful substrates on which the polyurethane foams can be
applied include, for example, papers or films which facilitate
simple detachment of the wound contact material before it is used
to cover an injured site. Human or animal tissue such as skin can
similarly serve as a substrate, so that direct closure of an
injured site is possible by a wound contact material produced in
situ.
[0146] The present invention further provides the polyurethane
wound dressing foams which comprise the polyurethane foams
obtainable by the process of the present invention.
[0147] Before drying, the foam densities of the polyurethane foams
are typically in the range from 50 to 800 g/liter, preferably in
the range from 100 to 500 g/liter and more preferably in the range
from 100 to 250 g/liter (mass of all input materials [in g] based
on the foam volume of one liter).
[0148] After drying, the polyurethane foams have a microporous, at
least partial open-cell structure comprising intercommunicating
cells. The density of the dried foams is typically below 0.4
g/cm.sup.3, preferably below 0.35 g/cm.sup.3, more preferably 0.01
to 0.3 g/cm.sup.3 and most preferably in the range from 0.1 to 0.3
g/cm.sup.3.
[0149] In accordance with the present invention, these dried
polyurethane foams typically have a physiological saline
absorbency, as measured by DIN EN 13726-1 Part 3.2, in the range of
100 to 1500%, preferably 300 to 1500% and more preferably in the
range from 300 to 800% (mass of liquid taken up, based on the mass
of dry foam). In addition, these dried polyurethane foams typically
have a water vapor transmission rate, as measured by DIN EN 13726-2
Part 3.2, in the range from 2000 to 8000 g/24 h*m.sup.2, preferably
in the range from 3000 to 8000 g/24 h*m.sup.2 and most preferably
in the range from 3000 to 5000 g/24 h*m.sup.2.
[0150] The polyurethane foams exhibit good mechanical strength and
high elasticity. Typically, maximum stress of the foams is greater
than 0.2 N/mm.sup.2 and maximum extension of the foams is greater
than 250%. Preferably, maximum stress of the foams is greater than
0.4 N/mm.sup.2 and the extension is greater than 350% (determined
according to DIN 53504).
[0151] After drying, the thickness of the polyurethane foams is
typically in the range from 0.1 mm to 50 mm, preferably in the
range from 0.5 mm to 20 mm, more preferably in the range from 1 to
10 mm and most preferably in the range from 1 to 5 mm.
[0152] The polyurethane foams can moreover be adhered, laminated or
coated to or with additional materials such as, for example,
materials based on hydrogels, (semi-) permeable films, coatings,
hydrocolloids or other foams.
[0153] If appropriate, a sterilizing step can be included in the
process of the present invention. It is similarly possible, at
least in principle, for polyurethane wound dressing foams produced
by the process of the present invention to be sterilized after they
have been formed. Conventional sterilizing processes are used where
sterilization is effected by thermal treatment chemicals such as
ethylenoxide or irradiation with gamma rays for example.
[0154] It is likewise possible to add, incorporate or coat these
polyurethane wound dressing foams with antimicrobially or
biologically active components. Such antimicrobially or
biologically active components include, for example, those which
have a positive effect with regard to wound healing and the
avoidance of germ loads.
[0155] Due to the wide utility of the process of the present
invention and of the polyurethane wound dressing foams obtainable
thereby, it is possible in principle to use this process in the
industrial production of polyurethane wound dressing foams. It is
similarly also possible to use this process for producing sprayed
plasters, for example, in which case the polyurethane wound
dressing foams are formed by direct application of the polyurethane
foam forming polyurethane foam forming composition to a wound, with
simultaneous frothing, and subsequent drying.
[0156] For the industrial production of polyurethane wound dressing
foams, component (I) the polyurethane dispersion is optionally
mixed with component (III) any of the optional foam auxiliaries of
the aforementioned kind, and thereafter mechanically frothed by
introduction of a gas such as air, and finally coagulated by
addition of component (II) the coagulant, to obtain a further
processible, coagulated foam. This foam is applied to a substrate
and dried. Owing to higher productivity, drying is typically
carried out at elevated temperatures in the range from 30 to
200.degree. C., preferably in the range from 50 to 150.degree. C.
and more preferably in the range from 60 to 130.degree. C.
Preference is further given to an at least two-stage drying
process, beginning at temperatures of 40 to 80.degree. C., and with
subsequent further drying at elevated temperatures of 80 to
140.degree. C. Drying is generally carried out using conventional
heating and drying apparatus such as, for example, (circulating
air) drying cabinets. Application and drying can each be carried
out batchwise or continuously, but preference is given to the
wholly continuous process.
[0157] When the polyurethane foam forming compositions of the
present inventionare used to produce a sprayed plaster, component
(I) the polyurethane dispersion and component (II) the coagulant,
which may each contain any optional components (III) including foam
auxiliaries if necessary and/or desired, are separately provided
and are then mixed with each other immediately before or during
application to the tissue which is to be covered. Frothing here is
accomplished by simultaneous decompression of a blowing gas which
was present in at least one of the components (I) and/or (II). To
consolidate the foam formed, it is subsequently dried. For drying
in this embodiment, temperatures of 20 to 40.degree. C. are
sufficient. When additional heat sources such as a hair dryer or an
IR red light lamp are used, forced thermal drying up to a maximum
temperature of 80.degree. C. is also possible. [0158] (1) The
blowing agents suitable for this embodiment are well known from
polyurethane chemistry. Suitable propellants are for example
n-butane, i-butane and propane and any mixtures of these
hydrocarbons. Equally suitable as propellant is also dimethylether.
Preferably, a mixture selected from n-butane, i-butane and propane
is used as propellant and the desired, fine-porous foams can be
obtained. The propellant or the mixture of propellants is typically
used in an amount from 1 to 50 wt.-%, preferably 5 to 40 wt.-%, and
particularly preferred 5 to 20 wt.-%, whereas the percentage of the
polyurethane dispersion (I), coagulant (II), propellant(s) and
auxiliary agents/additive materials (III) is equal to 100
wt.-%.
[0159] Spray plasters are preferably provided in spray cans, in
which (I) the polyurethane dispersion and (II) the cationic
coagulant are included separately from each other, and are not
mixed with each other until immediately before application. The
blowing agent can be included in either or both of the components
(I) and/or (II). Either or both of the components (I) and (II) may
additionally, if appropriate, also contain (III) one or more
auxiliary agents and/or additive materials, preferably foam
auxiliaries. Casting of the polyurethane foam forming polyurethane
foam forming composition is also possible, as well as spraying.
[0160] 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 percentages are percentages by
weight.
EXAMPLES
[0161] The solid contents were determined as specified in DIN-EN
ISO 3251.
[0162] NCO contents were determined, unless explicitly stated
otherwise, volumetrically as specified in DIN-EN ISO 11909.
[0163] The following substances were used in the examples:
TABLE-US-00001 Diaminosulfonate:
NH.sub.2--CH.sub.2CH.sub.2--NH--CH.sub.2CH.sub.2--SO.sub.3Na (45%
in water) Polyol 1: Polycarbonate polyol having an OH number of 56
mg KOH/g, and a number average molecular weight of 2000 g/mol
(commercially available as Desmophen .RTM. C2200 from Bayer
MaterialScience AG, Leverkusen, Germany) Polyol 2:
Polytetramethylene glycol polyol having an OH number of 56 mg
KOH/g, and a number average molecular weight of 2000 g/mol
(commercially available as PolyTHF .RTM. 2000 from BASF AG,
Ludwigshafen, Germany) Polyol 3: Polytetramethylene glycol polyol
having an OH number 112 mg KOH/g, and a number average molecular
weight of 1000 g/mol (commercially available as PolyTHF .RTM. 1000
from BASF AG, Ludwigshafen, Germany) Polyol 4: Monofunctional
polyether based on ethylene oxide/propylene oxide, having a number
average molecular weight of 2250 g/mol, and an OH number of 25 mg
KOH/g (commercially available as LB 25 polyether from Bayer
MaterialScience AG, Leverkusen, Germany) Stokal .RTM. STA: Foam
auxiliary aid based on ammonium stearate, active ingredient
content: 30% (commercially available from Bozzetto GmbH, Krefeld,
Germany) Stokal .RTM. SR: Foam auxiliary aid based on succinamate,
active ingredient content: about 34% (commercially available from
Bozzetto GmbH, Krefeld, Germany) Simulsol .TM. SL 26:
alkylpolyglycoside based on dodecylalcohol, about 52% queous
solution, Seppic GmbH, Cologne, DE Coagulant 1: Cationic
flocculation auxiliary aid containing the structures of formulae
(1) and (2), and having a solids content 25% by weight
(commercially available as Praestol .RTM. 185 K from Degussa AG,
Germany)
[0164] The mean of the average particle sizes (the number average
of which is reported) of the polyurethane dispersions (I) were
determined using laser correlation spectroscopy. (Specifically, the
instrument used was a Malvern Zetasizer 1000, Malver Inst.
Limited.)
Example 1
Polyurethane Dispersion 1
[0165] 987.0 g of Polyol 2, 375.4 g of Polyol 3, 761.3 g of Polyol
1 and 44.3 g of Polyol 4 were heated to 70.degree. C. in a standard
stirring apparatus. Then, a mixture of 237.0 g of hexamethylene
diisocyanate and 313.2 g of isophorone diisocyanate was added at
70.degree. C. over the course of 5 minutes, and the mixture was
stirred at 120.degree. C. until the theoretical NCO value was
reached or the actual NCO value was slightly below the theoretical
NCO value. The ready-produced prepolymer was dissolved with 4830 g
of acetone and, during the process, cooled down to 50.degree. C.,
and subsequently admixed with a solution of 25.1 g of
ethylenediamine, 116.5 g of isophoronediamine, 61.7 g of
diaminosulfonate and 1030 g of water metered in over 10 minutes.
The mixture was subsequently stirred for 10 minutes. Then, a
dispersion was formed by addition of 1250 g of water. This was
followed by removal of the solvent by distillation under reduced
pressure.
[0166] The white dispersion obtained had the following properties:
TABLE-US-00002 Solids content: 61% Particle size (LKS): 312 nm
Viscosity (viscometer, 23.degree. C.): 241 mPas pH (23.degree. C.):
6.02
Example 2
Polyurethane Dispersion 2
[0167] 34.18 g of Polyol 2, 85.1 g of Polyol 3, 172.6 g of Polyol 1
and 10.0 g of Polyol 4 were heated to 70.degree. C. in a standard
stirring apparatus. Then, a mixture of 53.7 g of hexamethylene
diisocyanate and 71.0 g of isophorone diisocyanate was added at
70.degree. C. over the course of 5 minutes, and the mixture was
stirred at 120.degree. C. until the theoretical NCO value was
reached or the actual NCO value was slightly below the theoretical
NCO value. The ready-produced prepolymer was dissolved with 1005 g
of acetone and, in the process, cooled down to 50.degree. C. and
subsequently admixed with a solution of 5.70 g of ethylenediamine,
26.4 g of isophoronediamine, 9.18 g of diaminosulfonate and 249.2 g
of water metered in over 10 minutes. The mixture was subsequently
stirred for 10 minutes. Then, a dispersion was formed by addition
of 216 g of water. This was followed by removal of the solvent by
distillation under reduced pressure.
[0168] The white dispersion obtained had the following properties:
TABLE-US-00003 Solids content: 63% Particle size (LKS): 495 nm
Viscosity (viscometer, 23.degree. C.): 133 mPas pH (23.degree. C.):
6.92
Example 3
Polyurethane Dispersion 3
[0169] 987.0 g of Polyol 2, 375.4 g of Polyol 3, 761.3 g of Polyol
1 and 44.3 g of Polyol 4 were heated to 70.degree. C. in a standard
stirring apparatus. Then, a mixture of 237.0 g of hexamethylene
diisocyanate and 313.2 g of isophorone diisocyanate was added at
70.degree. C. over the course of 5 minutes and the mixture was
stirred at 120.degree. C. until the theoretical NCO value was
reached or the actual NCO value was slightly below the theoretical
NCO value. The ready-produced prepolymer was dissolved with 4830 g
of acetone and, in the process, cooled down to 50.degree. C., and
subsequently admixed with a solution of 36.9 g of
1,4-diaminobutane, 116.5 g of isophoronediamine, 61.7 g of
diaminosulfonate and 1076 g of water metered in over 10 minutes.
The mixture was subsequently stirred for 10 minutes. Then, a
dispersion was formed by addition of 1210 g of water. This was
followed by removal of the solvent by distillation under reduced
pressure.
[0170] The white dispersion obtained had the following properties:
TABLE-US-00004 Solids content: 59% Particle size (LKS): 350 nm
Viscosity (viscometer, 23.degree. C.): 126 mPas pH (23.degree. C.):
7.07
Example 4
Polyurethane Dispersion 4
[0171] 201.3 g of Polyol 2, 76.6 g of Polyol 3, 155.3 g of Polyol
1, 2.50 g of 1,4-butanediol and 10.0 g of Polyol 4 were heated to
70.degree. C. in a standard stirring apparatus. Then, a mixture of
53.7 g of hexamethylene diisocyanate and 71.0 g of isophorone
diisocyanate was added at 70.degree. C. over the course of 5
minutes and the mixture was stirred at 120.degree. C. until the
theoretical NCO value was reached or the actual NCO value was
slightly below the theoretical NCO value. The ready-produced
prepolymer was dissolved with 1010 g of acetone and, in the
process, cooled down to 50.degree. C. and subsequently admixed with
a solution of 5.70 g of ethylenediamine, 26.4 g of
isophoronediamine, 14.0 g of diaminosulfonate and 250 g of water
metered in over 10 minutes. The mixture was subsequently stirred
for 10 minutes. Then, a dispersion was formed by addition of 243 g
of water. This was followed by removal of the solvent by
distillation under reduced pressure.
[0172] The white dispersion obtained had the following properties:
TABLE-US-00005 Solids content: 62% Particle size (LKS): 566 nm
Viscosity (viscometer, 23.degree. C.): 57 mPas pH (23.degree. C.):
6.64
Example 5
Polyurethane Dispersion 5
[0173] 201.3 g of Polyol 2, 76.6 g of Polyol 3, 155.3 g of Polyol
1, 2.50 g of trimethylolpropane and 10.0 g of Polyol 4 were heated
to 70.degree. C. in a standard stirring apparatus. Then, a mixture
of 53.7 g of hexamethylene diisocyanate and 71.0 g of isophorone
diisocyanate was added at 70.degree. C. over the course of 5
minutes, and the mixture was stirred at 120.degree. C. until the
theoretical NCO value was reached or the actual NCO value was
slightly below the theoretical NCO value. The ready-produced
prepolymer was dissolved with 1010 g of acetone and, in the
process, cooled down to 50.degree. C. and subsequently admixed with
a solution of 5.70 g of ethylenediamine, 26.4 g of
isophoronediamine, 14.0 g of diaminosulfonate and 250 g of water
metered in over 10 minutes. The mixture was subsequently stirred
for 10 minutes. Then, a dispersion was formed by addition of 293 g
of water. This was followed by removal of the solvent by
distillation under reduced pressure.
[0174] The white dispersion obtained had the following properties:
TABLE-US-00006 Solids content: 56% Particle size (LKS): 440 nm
Viscosity (viscometer, 23.degree. C.): 84 mPas pH (23.degree. C.):
6.91
Example 6
Polyurethane Dispersion 6
[0175] 1072 g of Polyol 2, 407.6 g of Polyol 3, 827 g of Polyol 1
and 48.1 g of Polyol 4 were heated to 70.degree. C. in a standard
stirring apparatus. Then, a mixture of 257.4 g of hexamethylene
diisocyanate and 340 g of isophorone diisocyanate was added at
70.degree. C. over the course of 5 minutes, and the mixture was
stirred at 120.degree. C. until the theoretical NCO value was
reached or the actual NCO value was slightly below the theoretical
NCO value. The ready-produced prepolymer was dissolved with 4820 g
of acetone and, in the process, cooled down to 50.degree. C. and
subsequently admixed with a solution of 27.3 g of ethylenediamine,
126.5 g of isophoronediamine, 67.0 g of diaminosulfonate and 1090 g
of water metered in over 10 minutes. The mixture was subsequently
stirred for 10 minutes. Then, a dispersion was formed by addition
of 1180 g of water. This was followed by removal of the solvent by
distillation under reduced pressure.
[0176] The white dispersion obtained had the following properties:
TABLE-US-00007 Solids content: 60% Particle size (LKS): 312 nm
Viscosity (viscometer, 23.degree. C.): 286 mPas pH (23.degree. C.):
7.15
Examples 7-12
Foams Produced From the Polyurethane Dispersions of Examples
1-6
[0177] The polyurethane dispersions produced as described in
Examples 1-6 were mixed with the foam auxiliaries as set forth in
the amounts indicated in Table 1 and frothed by means of a
commercially available hand stirrer (stirrer made of bent wire) to
a I liter foam volume. While stirring was continued, the foams
obtained were finally coagulated by addition of Coagulant 1 in the
amount set forth in Table 1; coagulation left foam volume unchanged
(slight increase in viscosity). Thereafter, the foams were drawn
down on silicone-coated paper by means of a blade coater set to the
gap height reported in Table 1. Table 1 similarly recites the
drying conditions for the foams produced as indicated. Clean white
foams having good mechanical properties and a fine porous structure
were obtained without exception. TABLE-US-00008 TABLE 1 Amount (g)
PU Sto- Sto- Coag- Foam Dispersion kal .RTM. kal .RTM. ulant SH
.sup.1) No. (Example) STA SR 1 (mm) Curing 7a 235.0 (1) 4.2 5.6 5.0
2 2 h/37.degree. C. 7b 235.0 (1) 4.2 5.6 5.0 4 18 h/37.degree. C.
7c 235.0 (2) 4.2 5.6 5.0 6 18 h/37.degree. C. 7d 235.0 (2) 4.2 5.6
5.0 4 18 h/37.degree. C., 30 min/ 120.degree. C. 7e 235.0 (2) 4.2
5.6 5.0 6 18 h/37.degree. C., 30 min/ 120.degree. C. 8 235.0 (2)
4.2 5.6 5.0 4 2 h/37.degree. C., 30 min/ 120.degree. C. 9 235.0 (3)
4.2 5.6 5.0 4 18 h/37.degree. C. 10 235.0 (4) 4.2 5.6 5.0 4 2
h/37.degree. C., 30 min/ 120.degree. C. 11 235.0 (5) 4.2 5.6 5.0 4
2 h/37.degree. C., 30 min/ 120.degree. C. 12 235.0 (6a) 4.2 5.6 5.0
4 2 h/37.degree. C., 30 min/ 120.degree. C. .sup.1) blade coater
gap height
[0178] As is evident from Table 2, all the foams exhibited a very
rapid imbibition of water, a high absorbence of physiological
saline ("free swell absorbency"), a very high moisture vapor
transmission rate (MVTR) and also good mechanical strength, in
particular after moist storage. TABLE-US-00009 TABLE 2 Imbibition
rate .sup.1) Free absorbency .sup.2) MVTR .sup.3) Foam No. (secs)
(g/100 cm.sup.2) (g/m.sup.2*24 h) 7a Not determined 13.4 6500 7b
Not determined 23.6 6300 7c Not determined 33.0 5100 7d 9 20.1 4400
7e 9 29.6 4200 8 7 21.4 4100 9 7 23.4 3700 10 18 20.2 4100 11 11
25.8 4300 12 17 22.1 4400 .sup.1) time for complete penetration of
a drop of distilled water into the foam (test on side facing the
paper); .sup.2) absorption of physiological saline determined
according to DIN EN 13726-1 Part 3.2 (5 test samples instead of 10
test samples); .sup.3) moisture vapor transition rate determined
according to DIN EN 13726-2 Part 3.2
[0179] Although the invention has been described in detail in the
foregoing for the purpose of illustration, it is to be understood
that such detail is solely for that purpose and that variations can
be made therein by those skilled in the art without departing from
the spirit and scope of the invention except as it may be limited
by the claims.
Example 13
[0180] 54 g of a polyurethane dispersion prepared according to
example 2 were mixed with 1,37 g of Simulsol.TM. SL 26. This
mixture was filled into one compartment of a suitable two component
spray can, and 1,37 g of Praestol.RTM. 185K were filled into the
other compartment of the spray can. Finally, 6 g of a mixture of
propellants consisting of i-butane/n-butane/propane were added.
After spraying (wet film thickness about 1 cm) and drying at
ambient conditions a plain white, fine-porous foam was
obtained.
* * * * *