PRODUCTION OF POROUS POLYURETHANE LAYERS

Abstract

The use of particular silicon-containing compounds in the production of porous polyurethane layers for improving the flow properties of the reaction mixture which is reacting to form the polyurethane layer and/or for optimizing the cells of the resulting polyurethane layer, preferably for homogenizing the cell structure over the entire resulting polyurethane layer, especially in the context of artificial leather or foam film production, is described. The silicon-containing compounds have the following formula:

##STR00001##

Claims

1. A porous polyurethane layer comprising at least one silicon-containing compound, wherein the silicon-containing compound has the formula (1) ##STR00011## where a is independently from 0 to 500, b is independently from 0 to 60, c is independently from 0 to 10, d is independently from 0 to 10, with the proviso that, for each molecule of the formula (1), the average number d of T units and the average number c of Q units per molecule is not greater than 50 in either case, the average number a of D units per molecule is not greater than 2000 and the average number b of the siloxy units bearing R.sup.1 per molecule is not greater than 100, R is independently at least one radical from the group of linear, cyclic or branched, aliphatic or aromatic, saturated or unsaturated hydrocarbon radicals having from 1 up to 20 carbon atoms, R.sup.2 is independently R.sup.1 or R, R.sup.1 is different from R and R.sup.1 is a radical selected from the group consisting of ##STR00012## CH.sub.2CH.sub.2CH.sub.2O(CH.sub.2CH.sub.2O).sub.x(CH.sub.2CH(R)O).sub.yR CH.sub.2CH.sub.2O(CH.sub.2CH.sub.2O).sub.x(CH.sub.2CH(R)O).sub.yR O(C.sub.2H.sub.4O).sub.x(C.sub.3H.sub.5O).sub.yR CH.sub.2R.sup.IV CH.sub.2CH.sub.2(O).sub.xR.sup.IV CH.sub.2CH.sub.2CH.sub.2OCH.sub.2CH(OH)CH.sub.2OH ##STR00013## CH.sub.2CH.sub.2CH.sub.2OCH.sub.2C(CH.sub.2OH).sub.2CH.sub.2CH.sub.3, where x is from 0 to 100, x is 0 or 1, y is from 0 to 100, R is independently an optionally substituted alkyl or aryl group having from 1 to 12 carbon atoms, substituted, for example, by alkyl radicals, aryl radicals or haloalkyl or haloaryl radicals, where different R is independently an substituted alkyl or aryl group having from 1 to 12 carbon atoms, substituted, for example, by alkyl radicals, aryl radicals or haloalkyl or haloaryl radicals, where different R substituents may be present within any R.sup.1 radical and/or any molecule of the formula (1), and R is independently a hydrogen radical or an alkyl group having from 1 to 4 carbon atoms, a C(O)R group with R=alkyl radical, a CH.sub.2OR group, an alkylaryl group, for example a benzyl group, or a C(O)NHR group, R.sup.IV is a linear, cyclic or branched, optionally substituted, e.g. substituted by halogens, hydrocarbon radical having from 1 to 50, carbon atoms, R.sup.V DG.sub.z where D is a linear, cyclic or branched, optionally substituted, e.g. substituted by heteroatoms such as O, N or halogens, saturated or unsaturated hydrocarbon radical having from 2 to 50, carbon atoms, G corresponds to one of the following formulae ##STR00014## z can be 0 or 1, where R.sup.1 can also be bridging in the sense that two or three siloxane structures of the formula (1) can be joined via R.sup.1, in which case R or R.sup.IV are correspondingly bifunctional groups, i.e. R.sup.V, R.sup.4 may independently be R, R.sup.1 and/or a functionalized, organic, saturated or unsaturated radical having substitution by heteroatoms, selected from the group of the alkyl, aryl, chloroalkyl, chloroaryl, fluoroalkyl, cyanoalkyl, acryloyloxyaryl, acryloyloxyalkyl, methacryloyloxyalkyl, methacryloyloxypropyl and vinyl radical, with the proviso that at least one substituent from R.sup.1, R.sup.2 and R.sup.4 is not R.

2. The porous polyurethane layer according to claim 1, wherein the thickness of the polyurethane layer is in the range from 0.05 to 5 mm.

3. The porous polyurethane layer according to claim 1, wherein the total amount of the silicon-containing compound(s) of the formula (1) used is, based on the finished polyurethane, from 0.01 to 10% by weight.

4. The porous polyurethane layer according to claim 1, wherein a solvent-free or low-solvent process is used for producing the porous polyurethane layer.

5. The porous polyurethane layer according to claim 1, wherein chemically blocked, NCO prepolymers and crosslinkers, comprising aliphatic and/or cycloaliphatic and/or aromatic amines having at least two primary and/or secondary amino groups are used for producing the porous polyurethane layer.

6. The porous polyurethane layer according to claim 1, wherein a polyol component, a catalyst and a polyisocyanate and/or a polyisocyanate prepolymer are used for producing the porous polyurethane layer.

7. The porous polyurethane layer according to claim 1 wherein the silicon-containing compound has the formula (1) wherein a is from 2 to 150, b is from 1 to 30, c is from 0 to 5, d is from 0 to 5, and R is a methyl radical.

8. A process for producing a composite structure comprising at least one porous polyurethane layer and a support layer, where the at least one porous polyurethane layer is applied directly or indirectly to a support layer and the at least one polyurethane layer is formed by applying a reactive composition capable of forming a polyurethane to the support layer and curing the reactive composition, wherein the formation of the porous polyurethane layer is carried out in the presence of a silicon-containing compound of the formula (1) ##STR00015## where a is independently from 0 to 500, b is independently from 0 to 60, c is independently from 0 to 10, d is independently from 0 to 10, with the proviso that, for each molecule of the formula (1), the average number d of T units and the average number c of Q units per molecule is not greater than 50 in either case, the average number a of D units per molecule is not greater than 2000 and the average number b of the siloxy units bearing R.sup.1 per molecule is not greater than 100, R is independently at least one radical from the group of linear, cyclic or branched, aliphatic or aromatic, saturated or unsaturated hydrocarbon radicals having from 1 up to 20 carbon atoms. R.sup.2 is independently R.sup.1 or R, R.sup.1 is different from R and is independently an organic radial and/or a polyether radical, R.sup.1 is a radical selected from the group consisting of ##STR00016## CH.sub.2CH.sub.2CH.sub.2O(CH.sub.2CH.sub.2O).sub.x(CH.sub.2CH(R)O).sub.yR CH.sub.2CH.sub.2O(CH.sub.2CH.sub.2O).sub.x(CH.sub.2CH(R)O).sub.yR O(C.sub.2H.sub.4O).sub.x(C.sub.3H.sub.5O).sub.yR CH.sub.2R.sup.IV CH.sub.2CH.sub.2(O).sub.xR.sup.IV CH.sub.2CH.sub.2CH.sub.2OCH.sub.2CH(OH)CH.sub.2OH ##STR00017## CH.sub.2CH.sub.2CH.sub.2OCH.sub.2C(CH.sub.2OH).sub.2CH.sub.2CH.sub.3, where x is from 0 to 100, x is 0 or 1, y is from 0 to 100, R is independently an optionally substituted alkyl or aryl group having from 1 to 12 carbon atoms, substituted, for example, by alkyl radicals, aryl radicals or haloalkyl or haloaryl radicals, where different R is independently an optionally substituted alkyl or aryl group having from 1 to 12 carbon atoms, substituted, for example, by alkyl radicals, aryl radicals or haloalkyl or haloaryl radicals, where different R substituents may be present within any R.sup.1 radical and/or any molecule of the formula (1), and R is independently a hydrogen radical or an alkyl group having from 1 to 4 carbon atoms, a C(O)R group with R=alkyl radical, a CH.sub.2OR group, an alkylaryl group, for example a benzyl group, or a C(O)NHR group, R.sup.IV is a linear, cyclic or branched, optionally substituted, e.g. substituted by halogens, hydrocarbon radical having from 1 to 50 carbon atoms, R.sup.V DG.sub.z where D is a linear, cyclic or branched, optionally substituted, e.g. substituted by heteroatoms such as O, N or halogens, saturated or unsaturated hydrocarbon radical having from 2 to 50 carbon atoms, G corresponds to one of the following formulae ##STR00018## z can be 0 or 1, where R.sup.1 can also be bridging in the sense that two or three siloxane structures of the formula (1) can be joined via R.sup.1, in which case R or R.sup.IV are correspondingly bifunctional groups, i.e. R.sup.V, R.sup.4 may independently be R, R.sup.1 and/or a functionalized, organic, saturated or unsaturated radical having substitution by heteroatoms, selected from the group of the alkyl, aryl, chloroalkyl, chloroaryl, fluoroalkyl, cyanoalkyl, acryloyloxyaryl, acryloyloxyalkyl, methacryloyloxyalkyl, methacryloyloxypropyl and vinyl radical, with the proviso that at least one substituent from R.sup.1, R.sup.2 and R.sup.4 is not R.

9. The process for producing a composite structure according to claim 8, wherein the reactive composition capable of forming a polyurethane comprises chemically blocked, NCO prepolymers and crosslinkers, comprising aliphatic and/or cycloaliphatic and/or aromatic amines having at least two primary and/or secondary amino groups.

10. The process for producing a composite structure according to claim 8, wherein the reactive composition capable of forming a polyurethane comprises i) a polyol having primary and/or secondary terminal hydroxy functions, ii) a polyisocyanate and/or a polyisocyanate prepolymer, and iii) a catalyst.

11. The composite structure comprising at least one porous polyurethane layer according to claim 7 and a support layer, wherein the two layers are joined indirectly or directly to one another.

12. The composite structure obtainable by the process according to claim 8.

13. An artificial leather comprising the composite structure according to claim 11.

14. A foam film comprising the composite structure according to claim 11.

15. The porous polyurethane layer according to claim 1, wherein the thickness of the polyurethane layer is in the range from 0.15 to 1 mm.

16. The porous polyurethane layer according to claim 1, wherein the total amount of the silicon-containing compound(s) of the formula (1) used is, based on the finished polyurethane, from 0.1 to 3% by weight.

17. The porous polyurethane layer according to claim 1, wherein chemically blocked, NCO prepolymers and crosslinkers, comprise aliphatic and/or cycloaliphatic and/or aromatic amines having at least two primary and/or secondary amino groups are used for producing the porous polyurethane layer.

18. The process for producing a composite structure according to claim 8, wherein the reactive composition capable of forming a polyurethane comprises oxime-blocked, NCO prepolymers and crosslinkers, comprising aliphatic and/or cycloaliphatic and/or aromatic amines having at least two primary and/or secondary amino groups.

19. The porous polyurethane layer according to claim 1 wherein the silicon-containing compound has the formula (1) wherein R.sup.1 is different from R and is independently an organic radial and/or a polyether radical, R.sup.1 is a radical selected from the group consisting of ##STR00019## CH.sub.2CH.sub.2CH.sub.2O(CH.sub.2CH.sub.2O).sub.x(CH.sub.2CH(R)O).sub.yR CH.sub.2CH.sub.2O(CH.sub.2CH.sub.2O).sub.x(CH.sub.2CH(R)O).sub.yR O(C.sub.2H.sub.4O).sub.x(C.sub.3H.sub.5O).sub.yR CH.sub.2R.sup.IV CH.sub.2CH.sub.2(O).sub.xR.sup.IV CH.sub.2CH.sub.2CH.sub.2OCH.sub.2CH(OH)CH.sub.2OH ##STR00020## where x is from 1 to 50, x is 0 or 1, y is from 1 to 50, R is independently an optionally substituted alkyl or aryl group having from 1 to 12 carbon atoms, substituted, for example, by alkyl radicals, aryl radicals or haloalkyl or haloaryl radicals, where different R is independently an optionally substituted alkyl or aryl group having from 1 to 12 carbon atoms, substituted, for example, by alkyl radicals, aryl radicals or haloalkyl or haloaryl radicals, where different R substituents may be present within any R.sup.1 radical and/or any molecule of the formula (1), and R is independently a hydrogen radical or an alkyl group having from 1 to 4 carbon atoms, a C(O)R group with R=alkyl radical, a CH.sub.2OR group, an alkylaryl group, for example a benzyl group, or a C(O)NHR group, R.sup.IV is a linear, cyclic or branched, optionally substituted, e.g. substituted by halogens, hydrocarbon radical having from 13 to 37 carbon atoms, R.sup.V DG.sub.z where D is a linear, cyclic or branched, optionally substituted, e.g. substituted by heteroatoms such as O, N or halogens, saturated or unsaturated hydrocarbon radical having from 4 to 37, carbon atoms, G corresponds to one of the following formulae ##STR00021## z can be 0 or 1, where R.sup.1 can also be bridging in the sense that two or three siloxane structures of the formula (1) can be joined via R.sup.1, in which case R or R.sup.IV are correspondingly bifunctional groups, i.e. R.sup.V, R.sup.4 may independently be R, R.sup.1 and/or a functionalized, organic, saturated or unsaturated radical having substitution by heteroatoms, selected from the group of the alkyl, aryl, chloroalkyl, chloroaryl, fluoroalkyl, cyanoalkyl, acryloyloxyaryl, acryloyloxyalkyl, methacryloyloxyalkyl, methacryloyloxypropyl and vinyl radical, with the proviso that at least one substituent from R.sup.1, R.sup.2 and R.sup.4 is not R.

20. The porous polyurethane layer according to claim 2 wherein the silicon-containing compound has the formula (1).

Description

EXAMPLES

[0180] Materials Used:

[0181] Polyether Siloxanes According to the Invention

[0182] Impranil HS 62 from Bayer Materialscience

[0183] Imprafix HS-C from Bayer Materialscience

[0184] Voranol CP 3322 from DOW (polyether triol having an OH number of 47 mg KOH/g)

[0185] Arcol 1374 from Bayer Materialscience (polyether polyol having an OH number of 28 mg KOH/g)

[0186] Polyether PPG 2470 from Evonik Industries AG

[0187] Kosmos 54 from Evonik Industries AG (catalyst based on zinc ricinoleate)

[0188] Monoethylene glycol from Dow

[0189] Desmophen 2200 from Bayer Materialscience (aliphatic polycarbonate diol)

[0190] Desmodur VP PU 0129 from Bayer Materialscience (mixture of 60% of diphenylmethane 2,4-diisocyanate and 40% of diphenylmethane 4,4-diisocyanate)

[0191] Desmodur 44V20L from Bayer Materialscience (mixture of diphenylmethane 4,4-diisocyanate (MDI) with isomeric and higher-functionality homologues)

[0192] Siliconized release paper from Sappi

[0193] Desmodur T 80 (TDI) from Bayer Materialscience (toluylene 2,4- and 2,6-diisocyanate (TDI) in a ratio of 80 : 20)

Example 1

Preparation of the Siloxanes

[0194] Siloxanes of the formula (1) according to the invention are prepared according to the processes known in the prior art by reacting corresponding hydrogen siloxanes by hydrosilylation. Allyl polyethers, vinyl polyethers, olefins and also compounds having a plurality of unsaturated groups were reacted to form compounds of the formula 1. The preparation was carried out by a method analogous to Example 7 in DE 1020070554852 and thus corresponding to the prior art for preparing SiC-bonded polyether siloxanes, as described, for example, in EP 1520870 and EP 0867465.

[0195] The polyethers used are summarized in Table 1.

TABLE-US-00001 TABLE 1 Polyethers used for preparing the compounds in Table 2 Polyether Starter R x= y= PE 1 Allyl alcohol H 12 0 PE 2 Allyl alcohol H 10 2 PE 3 Allyl alcohol H 12.5 3.5 PE 4 Allyl alcohol H 14.5 7 PE 5 Hydroxyethyl CH.sub.3 16 8 vinyl ether PE 6 Allyl alcohol Me 12.7 13.5 PE 7 Allyl alcohol H 20 4.5 PE 8 Allyl alcohol CH.sub.3 10 0 PE 9 Allyl alcohol H 35.5 37.5 PE 10 Allyl alcohol H 3.7 20.4 PE 11 Allyl alcohol Me 9.8 15.7 PE 12 Allyl alcohol Me 14.2 3.8 PE 13 Allyl alcohol H 35.5 37.5 PE 14 Allyl alcohol H 10.7 8.2 (x = ethylene oxide units, y = propylene oxide units, R = end group)

[0196] The structure of the siloxane compounds (SC) obtained can be seen from Table 2. The parameters shown in Table 2 relate to the abovementioned formula (1).

TABLE-US-00002 TABLE 2 Compositions of the silicon-containing compounds (SC) of the formula (1). SV R a R.sup.1 R.sup.4 b c d R.sup.2 Comp. 2 CH.sub.3 4 PE 8 CH.sub.3 4 0 0 R PE 12).sup.3 Comp. 3 CH.sub.3 20 PE 12 CH.sub.3 5 0 0 R 1 CH.sub.3 38 PE 1 CH.sub.3 10 0 0 R 2 CH.sub.3 20 PE 1 CH.sub.3 2 0 <<0.1 R 3 CH.sub.3 18 PE 3 CH.sub.3 0 0 <<0.1 R.sup.1 4 CH.sub.3 18 PE 1 CH.sub.3 5 0 <<0.1 R.sup.1 5 CH.sub.3 71 PE 9 CH.sub.3 4 0 <<0.1 R PE 11 PE 13).sup.1 6 CH.sub.3 38 PE 2 CH.sub.3 10 0 0 R PE 7 PE 14).sup.2 7 CH.sub.3 42 PE 6 CH.sub.3 6 0 0 R V1).sup.4 8 CH.sub.3 8 PE 8 CH.sub.3 10 0 0 R PE 12).sup.5 9 CH.sub.3 50 PE 4).sup.6 CH.sub.3 8 0 <<1 R.sup.1 10 CH.sub.3 50 PE 5 CH.sub.3 8 0 <<1 R 11 CH.sub.3 75 PE 6 CH.sub.3 3 0 <<1 R.sup.1 PE 9 PE 10).sup.7 12 CH.sub.3 65 PE 6 CH.sub.3 5 0 <<1 R.sup.1 PE 9).sup.8 13 CH.sub.3 40 PE 8 CH.sub.3 5 0 <<1 R 14 CH.sub.3 40 PE 4 CH.sub.3 3 0.5 2 R.sup.1 15 CH.sub.3 40 PE 3 CH.sub.3 3 0 1 R PE 4).sup.9 16 CH.sub.3 40 PE 6 C.sub.8H.sub.17 3 0.5 2 R.sup.1 17 CH.sub.3 55 PE 5 CH.sub.3 6 0.5 2 R.sup.1 18 CH.sub.3 42 PE 6 CH.sub.3 6 0 0 R V1).sup.17 19 CH.sub.3 71 PE 11 CH.sub.3 4 0 <<0.1 R PE 13 V 2).sup.10 20 CH.sub.3 42 PE 4 CH.sub.3 6 0 0 R V1).sup.11 21 CH.sub.3 42 PE 3 CH.sub.3 6 0 0 R V1).sup.12 22 CH.sub.3 20 PE 1 CH.sub.3 1 0 <<0.1 R.sup.1 23 CH.sub.3 42 PE 4 CH.sub.3 6 0 0 R PE 6).sup.13 24 CH.sub.3 42 PE 6 CH.sub.3 6 0 0 R 25 CH.sub.3 42 PE 10 CH.sub.3 6 0 0 R 26 CH.sub.3 62 PE 1 CH.sub.3 6 0 0 R PE 7).sup.14 27 CH.sub.3 20 PE 1 CH.sub.3 2 0 <<0.1 R.sup.1 V1).sup.15 28 CH.sub.3 20 PE 6 CH.sub.3 2 0 <<0.1 R.sup.1 V1).sup.15 ).sup.1 mixture consisting of 10 eq .% of PE 9 + 60 eq. % of PE 11 + 30 eq. % of PE 13 ).sup.2 mixture consisting of 30 eq. % of PE 2 + 25 eq. % of PE 7 + 45 eq. % of PE 14 ).sup.3 mixture consisting of 50 eq. % of PE 8 + 50 eq. % of PE 12 ).sup.4 mixture consisting of 90 eq. % of PE 6 + 10 eq. % of V1 (crosslinker 1: Trimethylolpropane diallyl ether) ).sup.5 mixture consisting of 70 eq. % of PE 8 + 30 eq. % of PE 12 ).sup.6 mixture consisting of 80 eq.% of PE 4 + 20 eq. % of C16-olefin ).sup.7 mixture consisting of 60 eq. % of PE 6 + 20 eq. % of PE 9 + 20 eq. % of PE 10 ).sup.8 mixture consisting of 60 eq. % of PE 6 + 40 q. % of PE 9 ).sup.9 mixture consisting of 50 eq. % of PE 3 + 50 eq. % of PE 4 ).sup.10 mixture consisting of 10 eq. % of V 2 + 60 eq. % of PE 11 + 30 eq. % of PE 13; (crosslinker 2: Polyethylene glycol diallyl ether, MW = 400) ).sup.11 mixture consisting of 90 eq. % of PE 4 + 10 eq. % of V1 (crosslinker 1: Trimethylolpropane diallyl ether) ).sup.12 mixture consisting of 90 eq. % of PE 3 + 10 eq. % of V 1 (crosslinker 1: Trimethylolpropane diallyl ether) ).sup.13 mixture consisting of 50 eq. % of PE 6 + 50 eq. % of PE 4 ).sup.14 mixture consisting of 50 eq. % of PE 1 + 50 eq. % of PE 7 ).sup.15 mixture consisting of 90 eq. % of PE 1 + 10 eq. % of V 1 (crosslinker 1: Trimethylolpropane diallyl ether) ).sup.16 mixture consisting of 90 eq. % of PE 6 + 10 eq. % of V 1 (crosslinker 1: Trimethylolpropane diallyl ether) ).sup.17 mixture consisting of 80 eq. % of PE 6 + 20 eq. % of V 1 (crosslinker 1: Trimethylolpropane diallyl ether)

[0197] In the comparative examples, use is made of:

[0198] Comp. 1: Dow Corning DC 193=polyether-modified methylpolysiloxane

[0199] Comp. 4: Baysilon OL 17=polyether-modified methylpolysiloxane

[0200] Comp. 5: without Si-containing compound

[0201] Methods Used

[0202] Weighing Out

[0203] All weighings were carried out using a Sartorius CPA 3202S.

[0204] Mechanical Foaming

[0205] The batches were foamed by means of a stirrer in such a way that particularly good incorporation of air bubbles was ensured.

[0206] Viscosity Determination

[0207] The viscosities were determined using a Brookfield Digital Viscometer. A spindle LV 4 was used at 6 rpm. In the case of viscosities above 100 000 mPas, 3 rpm were used.

[0208] Production of the Porous Polyurethane Layers

[0209] The films were drawn using a film drawing apparatus AB 3320 from TQC.

[0210] Drying

[0211] Drying ovens from the companies Heraeus and Binder were used for drying.

[0212] Film Thickness Determination

[0213] The film thickness was measured using a digital sliding caliper, Holex 41 2811 150. The measurement is carried out at five places uniformly distributed over the film. The arithmetic mean was calculated from the results of the five repetitions and reported as measurement result.

[0214] Determination of the Weight Per Unit Area

[0215] The length and width of the films was measured using a ruler and the mass was determined using a Sartorius CPA 3202S. The weight per unit area was calculated according to the following equation (length l, width b, mass m).

[00001]$m_A=\frac{m}{l.Math.b}$

[0216] Foam Density Determination

[0217] The thickness d of the films produced was measured. The density of the films .sub.Film was calculated therefrom:

[00002]${}_{\mathrm{Film}}=\frac{m_A}{d}$

[0218] Proportion of Cells

[0219] If the density of the unfoamed polyurethane .sub.Bulk is known, the percentage of cells Z can be calculated:

[00003]$Z=\left(1-\frac{{}_{\mathrm{Film}}}{{}_{\mathrm{Bulk}}}\right)*100.Math.\%$

[0220] The density of the raw materials was where necessary determined by a method based on DIN 51757.

[0221] Mechanical Data of the Films Produced

[0222] To determine the mechanical parameters, test specimens as shown in FIG. 1 were stamped from the films.

[0223] The measurement was carried out using a Zwick Roell Z010 tensile tester and a Zwick Roell KAF-TC load cell (nominal load 5 kN). The specimen was extended at a rate of advance of 500 mm/min. The elongation was recorded by means of strain gauges, at an initial length of 30 mm. The breaking stress .sub.br, the elongation at break .sub.br and the stress at 100% elongation .sub.100% were determined.

[0224] A five-fold determination was carried out in each case. The arithmetic mean of the measurement results was calculated.

[0225] Scanning Electron Microscopy (SEM)

[0226] The images for microscopic evaluation were recorded using a Hitachi TM 3000 scanning electron microscope at a magnification of 250.

[0227] Macroscopic and Microscopic Assessment

[0228] For the macroscopic evaluation, the surface of the films were looked at without an aid. The flow properties, the cell homogeneity and the homogeneity over an area were assigned the grades from 1 (poor) to 5 (very good).

[0229] For the microscopic evaluation, images of the cross section of the films were recorded using a scanning electron microscope (SEM). The cell homogeneity, the cell size and the proportion of open cells were evaluated.

[0230] In order to summarize the individual aspects in a value for evaluation, the sum of the squares of the individual aspects was calculated.

[0231] Formulation 1: General Formulation Based on Capped Isocyanates

[0232] 1000 parts of Impranil HS62, 69 parts of Imprafix HS-C and 20 parts of the respective silicon-containing compound according to the invention are stirred for 3 minutes at 1000 rpm by means of the abovementioned stirrer. The mixture is allowed to stand for 30 minutes.

[0233] Further Formulations Based on Uncapped Isocyanates

[0234] The constituents are stirred for 2 minutes at 2000 rpm by means of the abovementioned stirrer and subsequently processed further immediately.

TABLE-US-00003 TABLE 3 Formulations based on uncapped isocyanates Formu- Formu- Formu- Formu- Constituents lation 2 lation 3 lation 4 lation 5 Voranol CP 3322 50 90 Arcol 1374 50 50 Kosmos 54 0.2 0.2 0.2 0.2 Monoethylene 10 10 glycol Desmophen 2200 40 Polyether PPG 2470 40 40 Desmodur VP PU 54 0129 Dipropylene glycol 10 10 Desmodur 28 28 44V20L TDI 37 Siloxane 2 2 2 2

[0235] Production of the Porous Polyurethane Layers

[0236] The box doctor blades (300 and 600 m gap height) were filled with the mixtures corresponding to the formulations based on capped or uncapped isocyanates and porous polyurethane layers were drawn on release paper by means of the film drawing apparatus at a rate of advance of 30 mm/s. The layers were dried at 180 C. for 5 minutes. After cooling, the layers were mechanically removed from the release paper.

[0237] Analysis of the Porous Polyurethane Layers

TABLE-US-00004 TABLE 4 Macroscopic evaluation of the polyurethane layers based on capped isocyanates Cell Squares of Formu- Flow homo- Homogeneity the macr. SC lation properties geneity over the area evaluation 1 1 5 4 4 57 2 1 5 4 4 57 3 1 5 4 4 57 4 1 5 4 4 57 5 1 5 3 4 50 6 1 5 3 4 50 7 1 5 3 3 43 8 1 2 4 4 36 Comp. 1 4 2 3 29 1 Comp. 1 1 2 2 9 2 Comp. 1 1 2 2 9 3 Comp. 1 4 2 3 29 4 Comp. 1 1 3 2 14 5 9 1 5 3 4 50 10 1 5 4 3 50 11 1 5 4 3 50 12 1 4 3 4 41 13 1 4 3 5 50 14 1 4 3 4 41 15 1 4 5 2 45 16 1 4 4 4 48 17 1 5 4 2 45 18 1 4 3 4 41 19 1 5 4 3 50 20 1 4 3 4 41 21 1 5 3 5 59 22 1 4 4 3 41 23 1 5 5 3 59 24 1 5 4 2 45 25 1 5 4 4 57 26 1 4 3 4 41 27 1 4 4 3 41 28 1 5 4 4 57

TABLE-US-00005 TABLE 5 Macroscopic evaluation of the polyurethane layers based on uncapped isocyanates Cell Squares of Formu- Flow homo- Homogeneity the macr. SC lation properties geneity over the area evaluation 1 2 5 4 3 50 1 3 5 4 5 66 1 4 5 5 4 66 1 5 4 5 4 57 7 2 5 3 3 43 7 3 5 3 4 50 7 4 5 4 2 45 7 5 5 2 3 38 2 2 4 4 5 57 2 3 5 3 3 43 2 4 5 3 5 59 2 5 5 4 3 50 Comp. 1 2 3 3 2 22 Comp. 1 3 4 2 2 24 Comp. 1 4 3 2 3 22 Comp. 1 5 2 3 4 29 Comp. 5 2 2 3 4 29 Comp. 5 3 1 3 3 19 Comp. 5 4 1 2 3 14 Comp. 5 5 1 2 4 21 23 2 5 3 3 43 23 3 5 3 4 50 23 4 5 4 2 45 23 5 5 2 3 38 26 2 4 4 3 41 26 3 4 4 4 48 26 4 5 4 3 50 26 5 5 3 3 43

TABLE-US-00006 TABLE 6 Microscopic evaluation of the polyurethane layers based on capped isocyanates Squares of Form- Cell Proportion the micr. SC ulation Cell size homogeneity of open cells evaluation 1 1 2 3 3 22 2 1 4 3 1 26 3 1 4 2 2 24 4 1 4 3 3 34 5 1 4 4 3 41 6 1 2 2 3 17 7 1 2 2 3 17 8 1 2 3 3 22 Comp. 1 1 2 1 2 9 Comp. 2 1 2 2 1 9 Comp. 3 1 2 2 2 12 Comp. 4 1 2 1 1 6 Comp. 5 1 1 2 1 6 9 1 3 3 3 27 10 1 3 2 4 29 11 1 4 4 3 41 12 1 2 4 2 24 13 1 4 4 2 36 14 1 3 3 4 34 15 1 3 2 4 29 16 1 4 3 3 34 17 1 4 3 2 29 18 1 4 4 3 41 19 1 5 2 2 33 20 1 3 3 4 34 21 1 3 4 1 26 22 1 4 4 3 41 23 1 4 2 2 24 24 1 2 3 4 29 25 1 4 3 4 41 26 1 3 2 4 29 27 1 3 2 5 38 28 1 4 3 3 34

TABLE-US-00007 TABLE 7 Microscopic evaluation of the polyurethane layers based on uncapped isocyanates Proportion Squares of Cell Cell of open the macr. SC Formulation size homogeneity cells evaluation 1 2 5 5 4 66 1 3 5 4 4 57 1 4 5 4 3 50 1 5 4 5 4 57 7 2 4 4 5 57 7 3 4 5 3 50 7 4 5 4 5 66 7 5 5 4 3 50 2 2 3 4 4 41 2 3 4 3 3 34 2 4 4 4 5 57 2 5 5 4 3 50 Comp. 1 2 3 2 2 17 Comp. 1 3 2 2 4 24 Comp. 1 4 2 1 3 14 Comp. 1 5 3 2 3 22 Comp. 5 2 2 2 1 9 Comp. 5 3 2 3 1 14 Comp. 5 4 1 2 2 9 Comp. 5 5 1 2 3 14 23 2 5 5 4 66 23 3 5 4 4 57 23 4 5 4 3 50 23 5 4 5 4 57 26 2 4 4 5 57 26 3 4 5 3 50 26 4 5 4 5 66 26 5 5 4 3 50

TABLE-US-00008 TABLE 8 Basic macroscopic data for the polyurethane layers based on capped isocyanates Proportion Weight per unit Density of cells SCC Formulation area in g/m.sup.2 in kg/m.sup.3 in % 1 1 319 581 47 2 1 339 731 34 3 1 463 681 38 4 1 353 579 47 5 1 313 668 39 6 1 394 673 39 7 1 360 563 49 8 1 344 586 47 9 1 498 830 25 10 1 364 579 47 11 1 464 622 43 12 1 332 738 33 13 1 244 678 38 14 1 219 730 34 15 1 286 656 40 16 1 394 673 39 17 1 323 662 40 18 1 339 581 45 19 1 410 594 46 20 1 456 662 40 21 1 490 754 31 22 1 363 558 49 23 1 273 635 42 24 1 278 621 44 25 1 463 747 32 26 1 368 679 38 27 1 323 584 47 28 1 308 657 40 Comp. 1 1 503 967 12 Comp. 2 1 251 900 18 Comp. 3 1 179 861 22 Comp. 4 1 324 774 30 Comp. 5 1 504 919 16

TABLE-US-00009 TABLE 9 Basic macroscopic data for the polyurethane layers based on uncapped isocyanates Proportion of Weight per unit Density cells SC Formulation area in g/m.sup.2 in kg/m.sup.3 in % 1 2 260 650 41 1 3 285 671 39 1 4 310 561 49 1 5 305 649 41 7 2 320 734 33 7 3 275 663 40 7 4 336 737 33 7 5 410 661 40 2 2 342 697 37 2 3 298 683 38 2 4 313 683 38 2 5 346 676 39 Comp. 1 2 251 804 27 Comp. 1 3 263 824 25 Comp. 1 4 247 855 22 Comp. 1 5 256 921 16 None 2 186 899 18 None 3 203 923 16 None 4 186 877 20 None 5 181 862 22 23 2 321 682 38 23 3 316 652 41 23 4 331 643 42 23 5 309 636 42 26 2 362 662 40 26 3 379 661 40 26 4 354 636 42 26 5 321 682 38

TABLE-US-00010 TABLE 10 Mechanical properties of the polyurethane layers based on capped isocyanates Elongation at Stress at 100% Breaking stress break SC Formulation elongation in MPa in MPa in % 1 1 1.34 1.69 142 6 1 0.88 1.38 180 Comp. 5 1 0.99 1.03 97

[0238] The results of the comparative examples are, both in the case of the macroscopic and microscopic evaluations and also in the case of the mechanical properties, very significantly below the values obtained with the additives according to the invention. This also applies to the proportions of cells.