Fast-setting alkoxysilane spray foams

Abstract

The present invention relates to an isocyanate-free multi-component system, in particular for medical uses such as foamable wound coverings, with at least two separate components, wherein the first component comprises at least one alkoxysilane-terminated prepolymer and the second component comprises an aqueous component, wherein the aqueous component is a polyurethane dispersion.

Claims

1. An isocyanate-free multicomponent system comprising at least two separate components, the first component comprising at least one alkoxysilane-terminated prepolymer and the second component comprising an aqueous component, with the aqueous component comprising a polyurethane dispersion comprising 5 to 65 wt % of polyurethane based on the total weight of the polyurethane dispersion, wherein the alkoxysilane-terminated prepolymer comprises an alkoxysilane-terminated polyurethane prepolymer and an isocyanate-terminated prepolymer, wherein the alkoxysilane-terminated polyurethane prepolymer is prepared from an [(cyclohexylamino)methyl]triethoxysilane and an isocyanate-terminated prepolymer, and wherein the isocyanate-terminated prepolymer is prepared from a polyol and an aliphatic polyisocyanate, wherein the first and the second component of the multicomponent system are present in a volume ratio of 2:1 to 3:1 to one another.

2. The multicomponent system as claimed in claim 1, wherein the alkoxysilane-terminated polyurethane prepolymer comprises a polyesterpolyol and/or polyetherpolyol, the fraction of ethylene oxide units in the polyetherpolyol being not more than 50 wt %.

3. The multicomponent system as claimed in claim 1, wherein the weight average of the alkoxysilane-terminated prepolymer is 500 to 20 000 g/mol.

4. The multicomponent system as claimed in claim 1, wherein the polyurethane dispersion comprises 20 to 60 wt % of polyurethane.

5. The multicomponent system as claimed in claim 1, wherein the weight-average of the polyurethane in the polyurethane dispersion is 10 000 to 1 000 000 g/mol.

6. The multicomponent system as claimed in claim 1, wherein the polyurethane dispersion has a pH of between 5.0 and 9.0 at 20 C.

7. The multicomponent system as claimed in claim 1, wherein the first and/or the second component comprises an active medical ingredient selected from the group consisting of substances that release nitrogen monoxide under in vivo conditions, vitamins, provitamins, carotenoids, analgesics, antiseptics, hemostyptics, antihistamines, antimicrobial metals or salts thereof, plant-based wound healing promoter substances, plant extracts, enzymes, growth factors, enzyme inhibitors, and combinations thereof.

8. The multicomponent system as claimed in claim 1, wherein the first and the second component of the multicomponent system are present in a volume ratio of about 2.5:1 to one another.

9. The multicomponent system as claimed in claim 1, wherein the first and/or the second component comprises in each case a propellant gas.

Description

EXAMPLES

(1) General:

(2) Any amounts, proportions and percentages hereinbelow are based, unless otherwise stated, on the weight and the overall amount, or the overall weight, of the compositions.

(3) Unless noted otherwise, all analytical measurements relate to measurements at temperatures of 23 C.

(4) Methods:

(5) The solids contents are determined by heating a weighed sample to constant weight at 125 C. At constant weight, the sample is weighed again to ascertain the solids content.

(6) Unless expressly mentioned otherwise, NCO contents were determined volumetrically in accordance with DIN-EN ISO 11909.

(7) Monitoring for free NCO groups was carried out by means of IR spectroscopy (band at 2260 cm.sup.1).

(8) The reported viscosities were determined using rotary viscometry in accordance with DIN 53019 at 23 C. with a rotary viscometer at a rotary frequency of 18 s.sup.1 from Anton Paar Germany GmbH, Ostfildern, DE.

(9) The mean particle sizes (the number average being indicated) of the polyurethane dispersions were determined after dilution with deionized water by means of laser correlation spectroscopy (apparatus: Malvern Zetasizer 1000, Malvern Inst. Limited).

(10) The storage stability of the dispersions was tested over a period of 6 months after preparation, by storage at room temperature.

(11) The elongation at break was determined in accordance with DIN 53504.

(12) The maximum soluble propellant gas quantity was determined at 20 C. in test glasses for optical checks on aerosols from Pamasol Willi Mder AG, CH. The maximum soluble propellant gas quantity relates to the weight ratio of propellant gas to the substance/mixture under investigation, and was reached as soon as the propellant gas just failed to form a second phase on a permanent basis (>1 h).

(13) The mixtures were foamed up using a 2K spraying apparatus which was filled in the manner described in the PCT applications with the application numbers PCT/EP2011/063910 and PCT/EP2011/063909.

(14) Employed Substances and Abbreviations:

(15) Diaminosulfonate: NH.sub.2CH.sub.2CH.sub.2NHCH.sub.2CH.sub.2SO.sub.3Na (45% strength in water)

(16) HDI: hexamethylene 1,6-diisocyanate

(17) PolyTHF 2000: polytetramethylene glycol polyol, OH number 56 mg KOH/g, number-average molecular weight 2000 g/mol (BASF AG, Ludwigshafen, DE)

(18) PolyTHF 1000: polytetramethylene glycol polyol, OH number 112 mg KOH/g, number-average molecular weight 1000 g/mol (BASF AG, Ludwigshafen, DE)

(19) Desmophen C 2200: linear, aliphatic polycarbonatediol having terminal hydroxyl groups and a molecular weight of about 2000 g/mol, Bayer MaterialScience AG, Leverkusen, DE.

(20) Polyether LB 25: monofunctional polyether based on ethylene oxide/propylene oxide with number-average molecular weight of 2250 g/mol, OH number 25 mg KOH/g (Bayer MaterialScience AG, Leverkusen, DE)

(21) Desmodur N 3300: HDI trimer, NCO content 21.80.3 wt % (Bayer MaterialScience AG, Leverkusen, DE)

(22) Desmodur XP 2599: aliphatic prepolymer containing ether groups and based on HDI, NCO equivalent weight about 700 g (Bayer MaterialScience AG, Leverkusen, DE)

(23) Desmodur XP 2617: largely linear NCO prepolymer based on HDI, NCO content 12.51.0 wt % (Bayer MaterialScience AG, Leverkusen, DE)

(24) Geniosil XL 926: [(cyclohexylamino)methyl]triethoxysilane (Wacker Chemie AG, Munich, DE)

(25) P/B 3.5: mixture of propane and isobutane such as to give a gas pressure of 3.5 bar at 20 C.

(26) P/B 4.5: mixture of propane and isobutane such as to give a gas pressure of 4.5 bar at 20 C.

(27) DME: dimethyl ether

Example 1

Preparation of Aqueous Polyurethane Dispersion PUD1

(28) 450 g of PolyTHF 1000 and 2100 g of PolyTHF 2000 were heated to 70 C. Then a mixture of 225.8 g of hexamethylene diisocyanate and 298.4 g of isophorone diisocyanate was added and the mixture was stirred at 100-115 C. until the NCO value was slightly below the theoretical value. The completed prepolymer was dissolved with 5460 g of acetone at 50 C. and then a solution of 29.5 g of ethylenediamine, 143.2 g of diaminosulfonate and 610 g of water was metered in. Subsequent stirring time was 15 minutes. This was followed by dispersion by addition of 1880 g of water. The solvent was then removed by vacuum distillation to give a storage-stable dispersion having a solids content of 56%, a particle size of 276 nm and a viscosity of 1000 mPas. Not more than 3.1% of P/B 3.5 could be dissolved in the dispersion (solids content 48%) adjusted to a pH of 5.5 using aqueous citric acid.

Example 2

Preparation of Aqueous Polyurethane Dispersion PUD2

(29) 1645 g of PolyTHF 2000, 352.5 g of PolyTHF 1000 and 158.6 g of Polyether LB 25 were heated to 70 C. Then, at 70 C. over the course of 5 minutes, a mixture of 177 g of hexamethylene diisocyanate and 234 g of isophorone diisocyanate was added and the mixture was stirred until the NCO value was slightly below the theoretical value. The completed prepolymer was dissolved with 4560 g of acetone at 50 C. and then a solution of 23.1 g of ethylenediamine, 45.2 g of isophoronediamine and 294 g of water was metered in over the course of 10 minutes. Subsequent stirring time was 10 minutes. This was followed by dispersion by addition of 1650 g of water over the course of 10 minutes. The solvent was then removed by vacuum distillation to give a storage-stable dispersion having a solids content of 49%, a particle size of 255 nm and a viscosity of 420 mPas. A maximum of 20.5% of P/B 4.5 could be dissolved in the dispersion adjusted to a solids content of 30% using water.

Example 3

Preparation of Aqueous Polyurethane Dispersion PUD3

(30) 174.3 g of Desmophen C 2000, 37.3 g of PolyTHF 1000, 3.9 g of neopentyl glycol, 34.6 g of polypropylene glycol monobutyl ether having a number-average molar mass of 2500 g/mol, and 18.9 g of Polyether LB 25 were heated to 70 C. Then, at 70 C. over the course of 5 minutes, a mixture of 23.2 g of hexamethylene diisocyanate and 30.7 g of isophorone diisocyanate was added and the mixture was stirred until the NCO value was slightly below the theoretical value. After that, at 70 C., 4.4 g of N-methyldiethanolamine are added. The completed prepolymer was dissolved with 330 g of acetone at 50 C. and then a solution of 4.7 g of isophoronediamine in 8.4 g of acetone and, after 5 minutes, 0.1 g of ethylenediamine in 0.6 g of water was metered in. Subsequent stirring time was 10 minutes. Thereafter 35.3 g of 1-normal hydrochloric acid were added and after a further 5 minutes, over the course of 10 minutes, dispersion was carried out by addition of 740 g of water. The solvent was then removed by vacuum distillation to give a storage-stable dispersion having a solids content of 32%, a particle size of 273 nm and a viscosity of <50 mPas. A maximum of 21.1% of P/B 3.5 could be dissolved in the dispersion.

Example 4

Preparation of Aqueous Polyurethane Dispersion PUD4

(31) 159.4 g of PolyTHF 2000, 3.9 g of neopentyl glycol, 34.6 g of polypropylene glycol monobutyl ether having a number-average molar mass of 2500 g/mol, and 118.9 g of Polyether LB 25 were heated to 70 C. Then, at 70 C. over the course of 5 minutes, a mixture of 28.2 g of hexamethylene diisocyanate and 37.3 g of isophorone diisocyanate was added and the mixture was stirred until the NCO value was slightly below the theoretical value. After that, at 70 C., 4.4 g of N-methyldiethanolamine are added. The completed prepolymer was dissolved with 390 g of acetone at 50 C. and then a solution of 4.9 g of isophoronediamine in 8.7 g of acetone and, after 5 minutes, 0.1 g of ethylenediamine in 0.6 g of water was metered in. Subsequent stirring time was 10 minutes. Thereafter 35.3 g of 1-normal hydrochloric acid were added and after a further 5 minutes, over the course of 10 minutes, dispersion was carried out by addition of 880 g of water. The solvent was then removed by vacuum distillation to give a storage-stable dispersion having a solids content of 30%, a particle size of 149 nm and a viscosity of <50 mPas. A maximum of 27.1% of PB 3.5 could be dissolved in the dispersion.

Example 5

Preparation of Aqueous Polyurethane Dispersion PUD5

(32) 70.0 g of PolyTHF 1000, 326.7 g of PolyTHF 2000, 22.9 g of neopentyl glycol, and 42.7 g of Polyether LB 25 were heated to 70 C. Then, at 70 C. over the course of 5 minutes, a mixture of 53.8 g of hexamethylene diisocyanate and 71.1 g of isophorone diisocyanate were added and the mixture was stirred until the NCO value was below the theoretical value. Thereafter, at 70 C., 9.2 g of N-methyldiethanolamine were added. The completed prepolymer was dissolved with 600 g of acetone at 50 C., and then a solution of 13.7 g of isophoronediamine in 24.3 g of acetone was metered in. The subsequent stirring time was 10 minutes. Thereafter 73.2 g of 1-normal hydrochloric acid were added and after a further 5 minutes, over the course of 10 minutes, dispersion was carried out by addition of 1350 g of water. This was followed by the removal of the solvent by vacuum distillation to give a storage-stable dispersion having a solids content of 30%, a particle size of 301 nm, and a viscosity of <50 mPas.

(33) The examples which follow demonstrate the preparation of silane-terminated prepolymers.

Example 6

Preparing Silane-Terminated Prepolymer STP1

(34) A mixture of 1000 g HDI and 1 g of benzoyl chloride was admixed dropwise at 80 C. over the course of 3 hours with 1000 g of a polyalkylene oxide having a molar mass of 4680 g/mol, prepared starting from glycerol, with an ethylene oxide weight fraction of 71% and a propylene oxide weight fraction of 26%, dried beforehand under a pressure of 0.1 mbar and at 100 C. for 6 hours, this dropwise addition being followed by stirring for 12 hours. The excess HDI was removed by thin-film distillation at 130 C. and 0.1 mbar. This gave a prepolymer having an NCO content of 2.42% and a viscosity of 3500 mPas.

(35) 200 g of the resulting prepolymer were subsequently admixed at 30-40 C. over the course of 10 minutes with 31.7 g of Geniosil XL 926. After a further 60 minutes of stirring at 30 C., complete conversion of the NCO prepolymer to the STP was detectable by IR spectroscopy. This gave a viscous, colorless liquid.

Example 7

Preparing Silane-Terminated Prepolymer STP2

(36) 390 g of Desmodur N 3300 were admixed dropwise at 80 C. with 1125 g of a polyalkylene oxide having a molar mass of 2250 g/mol, prepared starting from butyl diglycol and with an ethylene oxide weight fraction of 79% and a propylene oxide weight fraction of 14%, dried beforehand at 100 C. for 2 hours under a pressure of 0.1 mbar, and the dropwise addition was followed by stirring at 80 C. until the NCO content of 3.67% was reached.

(37) 5.0 g of the resulting prepolymer were subsequently admixed at room temperature over the course of 10 minutes with 1.2 g of Geniosil XL 926. After a further 30 minutes of stirring, complete conversion of the NCO prepolymer to the STP was detectable by IR spectroscopy. This gave a viscous, colorless liquid.

Example 8

Preparing Silane-Terminated Prepolymer STP3

(38) 490 g of Desmodur XP 2599 were admixed dropwise at 80 C. with 394 g of a polyalkylene oxide having a molar mass of 2250 g/mol, prepared starting from butyl diglycol and with an ethylene oxide weight fraction of 79% and a propylene oxide weight fraction of 14%, dried beforehand at 100 C. for 2 hours under a pressure of 0.1 mbar, and the dropwise addition was followed by stirring at 80 C. until the NCO content of 2.22% was reached.

(39) A solution of 51.8 g of the resulting prepolymer in 70 g of dry diethyl ether was subsequently admixed at room temperature over the course of 10 minutes with 7.5 g of Geniosil XL 926. After a further 30 minutes of stirring, complete conversion of the NCO prepolymer to the STP was detectable by IR spectroscopy. This gave a viscous, colorless liquid.

Example 9

Preparing Silane-Terminated Prepolymer STP4

(40) A solution of 50 g of Desmodur XP 2617 in 55 g of dry acetone was admixed at 30 C. over the course of 30 minutes with 42 g of Geniosil XL 926. After a further 30 minutes of stirring at 40 C., complete conversion of the NCO prepolymer to the STP was detected by IR spectroscopy. This gave a viscous, colorless liquid.

Example 10

Preparing Silane-Terminated Prepolymer STP5

(41) A mixture of 800 g of a polyalkylene oxide having a molar mass of 2000 g/mol, prepared starting from 1,2-propylene glycol, and with an ethylene oxide weight fraction of 47% and a propylene oxide weight fraction of 49%, dried beforehand under a pressure of 0.1 mbar at 80 C. for 1 hour, and 2.8 g of benzoyl chloride was admixed dropwise at 80 C. over the course of 45 minutes with 1000 g of HDI, followed by stirring for 2 hours. The excess HDI was removed by thin-film distillation at 130 C. and 0.4 mbar. This gave a prepolymer having an NCO content of 3.43% and a viscosity of 1250 mPas.

(42) 498 g of the resulting prepolymer were subsequently admixed at 30-40 C. over the course of 15 minutes with 104.5 g of Geniosil XL 926. After a further 60 minutes of stirring at 30 C., complete conversion of the NCO prepolymer to the STP was detectable by IR spectroscopy. The resulting STP had a higher viscosity compared to the NCO prepolymer used.

Example 11

Preparing Silane-Terminated Prepolymer STP6

(43) A mixture of 1032 g of a polyalkylene oxide having a molar mass of 4000 g/mol, prepared starting from 1,2-propylene glycol, and with an ethylene oxide weight fraction of 13% and a propylene oxide weight fraction of 86%, dried beforehand under a pressure of 0.1 mbar at 80 C. for 1 hour, and 1.8 g of benzoyl chloride was admixed dropwise at 80 C. over the course of 30 minutes with 650 g of HDI, followed by stirring for 4 hours. The excess HDI was removed by thin-film distillation at 130 C. and 0.03 mbar. This gave a prepolymer having an NCO content of 1.82% and a viscosity of 2100 mPas.

(44) 207.5 g of the resulting prepolymer were subsequently admixed at 30-40 C. over the course of 15 minutes with 24.8 g of Geniosil XL 926. After a further 30 minutes of stirring at 30 C., complete conversion of the NCO prepolymer to the STP was detectable by IR spectroscopy. The resulting STP had a higher viscosity compared to the NCO prepolymer used.

Example 12

Preparing Silane-Terminated Prepolymer STP7

(45) A mixture of 398 g of a polyalkylene oxide having a molar mass of 4800 g/mol, prepared starting from glycerol, and with an ethylene oxide weight fraction of 13% and a propylene oxide weight fraction of 85%, dried beforehand under a pressure of 0.1 mbar at 80 C. for 1 hour, and 0.7 g of benzoyl chloride was admixed dropwise at 80 C. over the course of 30 minutes with 315 g of HDI, followed by stirring for 2 hours. The excess HDI was removed by thin-film distillation at 140 C. and 0.07 mbar. This gave a prepolymer having an NCO content of 2.10%.

(46) 200 g of the resulting prepolymer were subsequently admixed at 30-40 C. over the course of 10 minutes with 27.6 g of Geniosil XL 926. After a further 60 minutes of stirring at 30 C., complete conversion of the NCO prepolymer to the STP was detectable by IR spectroscopy. This gave a viscous, colorless liquid.

Example 13

Preparing Silane-Terminated Prepolymer STP8

(47) A mixture of 201 g of a polyalkylene oxide having a molar mass of 1000 g/mol, prepared starting from 1,2-propylene glycol, and with a propylene oxide weight fraction of 92%, dried beforehand under a pressure of 0.1 mbar at 80 C. for 1 hour, and 0.8 g of benzoyl chloride was admixed dropwise at 80 C. over the course of 30 minutes with 588 g of HDI, followed by stirring for 2 hours. The excess HDI was removed by thin-film distillation at 140 C. and 0.05 mbar. This gave a prepolymer having an NCO content of 6.09%.

(48) 200 g of the resulting prepolymer were subsequently admixed at 30-40 C. over the course of 10 minutes with 80 g of Geniosil XL 926. After a further 60 minutes of stirring at 30 C., complete conversion of the NCO prepolymer to the STP was detectable by IR spectroscopy. This gave a viscous, colorless liquid.

Example 14

Preparing Silane-Terminated Prepolymer STP9

(49) A mixture of 189 g of a polyesterpolyol based on diethylene glycol and adipic acid having a molar mass of 1000 g/mol, dried beforehand under a pressure of 5 mbar at 80 C. for 30 minutes, and 0.9 g of benzoyl chloride was admixed dropwise at 70-80 C. over the course of 40 minutes with 477 g of HDI, followed by stirring for 2 hours. The excess HDI was removed by thin-film distillation at 140 C. and 0.05 mbar. This gave a prepolymer having an NCO content of 5.81% and a viscosity of 6100 mPas.

(50) 160 g of the resulting prepolymer were subsequently admixed at 30-40 C. over the course of 15 minutes with 61 g of Geniosil XL 926. After a further 30 minutes of stirring at 30 C., complete conversion of the NCO prepolymer to the STP was detectable by IR spectroscopy. This gave a viscous, colorless liquid.

Example 15

Preparing Silane-Terminated Prepolymer STP10

(51) A mixture of 423 g of a polyalkylene oxide having a molar mass of 3825 g/mol, prepared starting from trimethylolpropane, and with an ethylene oxide weight fraction of 13% and a propylene oxide weight fraction of 83%, dried beforehand under a pressure of 0.1 mbar at 80 C. for 1 hour, and 0.8 g of benzoyl chloride was admixed dropwise at 80 C. over the course of 30 minutes with 420 g of HDI, followed by stirring for 2 hours. The excess HDI was removed by thin-film distillation at 130 C. and 0.03 mbar. This gave a prepolymer having an NCO content of 2.84%.

(52) 200 g of the resulting prepolymer were subsequently admixed at 30-40 C. over the course of 10 minutes with 37 g of Geniosil XL 926. After a further 60 minutes of stirring at 30 C., complete conversion of the NCO prepolymer to the STP was detectable by IR spectroscopy. This gave a viscous, colorless liquid.

Example 16

Preparing Silane-Terminated Prepolymer STP11

(53) A mixture of 270 g of the NCO prepolymer prepared according to Example 10 and 1349 g of the NCO prepolymer prepared according to Example 11 was admixed dropwise at 30-40 C. over the course of 30 minutes with 217 g of Geniosil XL 926, and the product was stirred at 30 C. for a further 30 minutes. Complete conversion of the NCO prepolymer to the STP was detected by IR spectroscopy. The product was a viscous, colorless liquid.

(54) In the subsequent experiments, the results of the curing tests on the foams are depicted.

Example 17

Curing of STP and PUD as a Foam

(55) 38.6 g of DME and 4.3 g of P/B 3.5 were dissolved in 100 g of prepolymer STP1.

(56) 1.2 g of P/B 3.5 were dissolved in 40 g of PUD5.

(57) The two components were each individually introduced into one chamber, respectively, of a 2K spraying apparatus operated by compressed air. Synchronous delivery of both components in the volume ratio 2.5 (STP):1 (PUD) took place via a static mixer in which commixing took place. With foaming and complete curing within about 60 seconds, a colorless, elastic, fine-cell foam was obtained.

Example 18

Curing of STP and PUD as a Foam

(58) 26.6 g of n-butane were dissolved in 100 g of prepolymer STP11. 1.2 g of P/B 3.5 were dissolved in 40 g of PUD5.

(59) The two components were each individually introduced into one chamber, respectively, of a 2K spraying apparatus operated by compressed air. Synchronous delivery of both components in the volume ratio 2.5 (STP):1 (PUD) took place via a static mixer in which commixing took place. With foaming and complete curing within about 10 seconds, a colorless, elastic, fine-cell foam was obtained.

Example 19

Curing of STP and PUD as a Foam

(60) 44.9 g of DME were dissolved in 100 g of prepolymer STP9. 1.2 g of P/B 3.5 were dissolved in 40 g of PUD5.

(61) The two components were each individually introduced into one chamber, respectively, of a 2K spraying apparatus operated by compressed air. Synchronous delivery of both components in the volume ratio 2.5 (STP):1 (PUD) took place via a static mixer in which commixing took place. With foaming and complete curing within about 30 seconds, a colorless, elastic foam was obtained.

Example 20

Curing of STP and PUD as a Foam

(62) 40.8 g of P/B 3.5 were dissolved in 100 g of prepolymer STP11. 40 g of PUD5 were used without gassing.

(63) The two components were each individually introduced into one chamber, respectively, of a 2K spraying apparatus operated by compressed air. Synchronous delivery of both components in the volume ratio 2.5 (STP):1 (PUD) took place via a static mixer in which commixing took place. With foaming and complete curing within about 5 seconds, a colorless, elastic, fine-cell foam was obtained.

Example 21

Curing of STP and PUD as a Foam

(64) 31.6 g of DME were dissolved in 100 g of prepolymer STP5. 3.1 g of P/B 3.5 were dissolved in 40 g of PUD 1, which had been adjusted beforehand using citric acid to a pH of 5.5.

(65) The two components were each individually introduced into one chamber, respectively, of a 2K spraying apparatus operated by compressed air. Synchronous delivery of both components in the volume ratio 2.5 (STP):1 (PUD) took place via a static mixer in which commixing took place. With foaming and complete curing within about 60 seconds, an elastic compact foam with a filmed surface was obtained.

(66) These examples demonstrate that starting from a variety of original substances, i.e. polyurethane dispersions and silane prepolymers, it is possible to produce a multiplicity of different foams. And yet the compositions can be used not only for producing foams, but also, as shown by the following examples, as a starting basis for the production of casting compositions.

Example 22

Curing of STP and PUD as Casting Composition

(67) 100 g of prepolymer STP11 and 33 g of PUD1 were rapidly stirred with one another and applied to release paper in a layer thickness of approximately 6 mm. The material, which has a high viscosity after just 10 seconds, was cured fully within 30 seconds. This gave a compact cast material having an elongation at break of 35%.

Comparative Example According to EP 1 829 908, Example 1

(68) The aim with this comparative experiment is to compare the inventive function of the polyurethane dispersion with the 2K systems known from the prior artin the present case, with Example 1 of EP 1 829 908. No P/B 3.5 propellant gas could be dissolved in component 2 (8 parts water, 13 parts citric acid) in this case. On account of this fact, this composition cannot be satisfactorily delivered from the 2K spraying apparatus, since it was not possible to set exactly the mixing proportions between the prepolymer component and the aqueous component, and since it was not possible to achieve sufficient foaming of the mixture, either.