MXPA97003173A - A method for preparing flexi polyurethane foams - Google Patents

Abstract

This invention relates to a method for preparing a polyurethane plate supply foam, flexible by the reaction of a polyol, an organic diisocyanate and water in the presence of at least one urethane catalyst, a siloxane-oxyalkylene copolymer surfactant and optionally, another blowing agent, where the surfactant has the average formula MDxD'yM where M is (CH3) 3SiO1 / 2 or R (CH3) 2SiO1 / 2, D is (CH3) 2SiO2 / 2, D'is (CH3 ) RSiO2 / 2, and the value of X + y is from 48 to 220, the ratio x / y is from 5 to 15 inclusive, R is a polyether-containing substituent selected from the group consisting of (1) a CnH2nO group ( C2H4O) a (C3H6O) bR'that have an average molecular weight in the range of 2300-3400 and in which n is 3-4, the ratio a / b is 0.5 to 1.3 inclusive, R'represents hydrogen, an alkyl group of 1-4 carbon atoms or -C (O) CH 3 and (2) a group -C n, H 2n, O (C 2 H 4 O) a, (C 3 H 6 O) b, R 'which have average molecular weight in the range of 750-1400 and where n'es 3-4, a'is a number such that the residues of ethylene oxide constitute 30-100% by weight of the alkylene oxide residues of the polyether, d is such a number that the residues of propylene oxide they constitute 0.7% by weight of the alkylene oxide residues of the polyether, R 'represents hydrogen, an alkyl group of 1-4 carbon atoms or -C (O) CH3 and the average mixture of the molecular weight of the R substituents containing total polyether in the surfactant, it is in the range of 1500-2200 and the molar ratio of EO / PO is in the range of 0.65-1

Description

A METHOD FOR PREPARING FLEXIBLE POLYURETHANE FOAMS DESCRIPTION PATENT APPLICATION OF THE UNITED STATES of which the following is a specification. This is a continuation in part of copending application Serial No. 08 / 577,588, filed December 22, 1995. This invention relates to flexible polyurethane foams, and more specifically to a method for preparing flexible polyurethane foams containing surfactants of silicone polyether having a siloxane backbone and oxyalkylene branch groups. In the manufacture of the polyurethane foam, the surfactants are required to stabilize the foam until the chemical reactions forming the polymer are sufficiently complete, such that the foam is self-supporting and does not experience objectionable compression. Silicone polyether surfactants for the manufacture of polyurethane foam are typically materials having siloxane backbones and polyether groups as branches. There are two types, non-hydrolysable and hydrolysable. Non-hydrolysable surfactants, in which the polyether groups as branches are attached to the siloxane backbone via Si-C bonds, are generally believed to provide high efficiencies, but poor processing latitudes. Hydrolysable surfactants, in which the branched polyether groups are attached to the siloxane backbone via linkages, Si-OC, are generally believed to have low efficiencies but wide latitudes of processing. The present invention provides non-hydrolyzable silicone surfactants, which provide excellent emulsification, efficiency and wide latitude of processing in the formation of foams supplied as flexible polyurethane plates, especially in foam formulations supplied in plates containing high water levels and low isocyanate rates. In addition, the foams supplied in flexible polyurethane plates produced with a silicone surfactant of the present invention, showed better foam heights, while maintaining the finer cell structures, than the foams produced with other surfactants. Surfactants are compositions of matter having the average formula MD? D '^ I in which M represents (CH3) 3Si01 / 2 or R (CH3 ^ SiO ^, D represents (CH3) 2si02 / 2 'D' represents (CH3) RSi02 / 2, the value of x + y is from 48 to 220 and the ratio x / y is from 5 to 15 inclusive. In the above formula for M and D ', R is a polyether containing a substituent selected from the group consisting of: (1) -CNH2nO (C2H40) to (C3H60) bR' portions having an average weight of molecular weights in the range of 2300-3400 and where n is 3-4, the ratio a / b is 0.5 to 1.3 inclusive, R 'represents hydrogen, an alkyl group of 1-4 carbon atoms or -C (0) CH3 and (2) the portions -Cn, H2ntO (C2H40) a, (C3H60) jj.R 'having average weight of molecular weights in the range of 750-1400 and in which n' is 3-4, a 'is a number such that the residues of ethylene oxide constitute 30-100% by weight of the alkylene oxide residues of the polyether, d 'is a number such that the residues of propylene oxide constitute 0-70% by weight of the alkylene oxide residues of the polyether, R 'represents hydrogen, an alkyl group of 1-4 carbon atoms or -C (0) CH3. In addition, the MD-.D '.- M surfactant compositions of the invention contain polyether-containing R substituents having an average molecular weight in the range of 2300-3400 and polyether-containing R substituents having an average weight of molecular weights in the range of 750-1400 and the average molecular weight mixtures of R-substituents containing total polyether in the MD? D'and M surfactants is in the range of 1500-2200 and the total ratio of ethylene oxide residues (EO) in both of the polyethers to residues of propylene oxide (PO) in both polyethers, that is, the total EO / PO molar ratio is in the range of 0.65-1.2. The invention of this form relates to a method for preparing a foam for the supply of flexible polyurethane plates by reacting a polyol, an organic diisocyanate and water in the presence of at least one catalyst for the production of polyurethane foam, optionally another blowing agent and the siloxane-oxyalkylene copolymer surfactant as defined above. This invention also relates to a polyurethane foam produced using the method described in the foregoing. The surfactants used in this invention are compositions of matter having the average formula where M represents (CH3) 3SiO -, / 2 ° R (CH3) 2sio? / 2 'D represents (CH3) 2si02 / 2' D 'represents (CH3) RSi02 / 2, and the value of x + y is from 48 to 220, and the ratio x / y is from 5 to 15 inclusive. In the above formulas for M and D '(R is a polyether-containing substituent selected from the group consisting of: (1) -CNH2n0 (C2H40) to (C3H60) bR- portions having an average molecular weight in the range of 2300-3400 and where n is 3-4, the ratio a / b is 0.5 to 1.3 inclusive, R 'represents hydrogen, an alkyl group of 1-4 carbon atoms or -C (0) CH3 and ( 2) the portions -Cn, H2n, 0 (C2H40) a, (C3H60) jj.R 'having average weight of molecular weights in the range of 750-1400 and in which n1 is 3-4, a' is a number such that the residues of ethylene oxide constitute 30-100% by weight of the alkylene oxide residues of the polyether, d 'is a number such that the residues of propylene oxide constitute 0-70% by weight of the alkylene oxides residues of the polyether, R 'represents hydrogen, an alkyl group of 1-4 carbon atoms or -C (0) CH3 In addition, the MD- D'. and M surfactant compositions of the invention, contain substituents R containing polyether having an average molecular weight in the range of 2300-3400 and R substituents containing polyether having an average molecular weight in the range of 750-1400 and the average molecular weight mixtures of the substituents R containing total polyether in the surfactants MD? D'.J ^ is in the range of 1500-2200 and the total ratio of ethylene oxide to residues of propylene oxide ie the general EO / PO molar ratio is in the range of 0.65-1.2. Within the wide range of surfactant compositions of the invention as defined, there are many preferred materials. The preferred material has the general average formula MD44-63D '5.5-12.5M- A more preferred material within this class has the general average formula MD60-62D' 7-8M- The polyether-containing R substituents having the average molecular weight of the molecular weights in the range of 2300-3400 are preferably the C3HgO (C2_H40) to (C3-Hg0) bR 'portions with an a / b ratio of 1.0 and having an average molecular weight of about 3100. R1 is preferably -C (0) CH3. The polyether-containing R substituents having an average molecular weight in the range of 750-1400 are preferably the C3HgO (C2H40) to (C3HgO) bR 'portions containing about 43% by weight of the ethylene oxide residues. and having an average molecular weight of about 1250. R 'is preferably -C (0) CH3. The mixture of the average weight of the molecular weight of the polyether-containing R substituents in the MD? D 'surfactant compositions. 1 is preferably in the range of 1650-1900. The total average EO / PO molar ratio is preferably about 1.0. Methods for synthesizing non-hydrolysable surfactants having polyalkylene oxide branching groups are well known. Representative descriptions are provided in U.S. Patent Nos. 4,147,847 and 4,855,379, which are incorporated herein by reference.

Typically, the surfactants of the invention are prepared by causing a polyhydrosiloxane of the generalized average formula M * D? D "M * to react with an appropriately chosen mixture of allyloxyalkylene polyethers in the presence of a hydrosilation catalyst such as chloroplatinic acid. the polyhydrosiloxane, M * is (CH3) 3Si01 / 2 or (H) (CH3) 2Si01 2, D is as defined above and D "is (CH3) (H) SiO2 / • Allyloxyalkylenepolyethers are polyethers having a terminal vinyl group and containing multiple units derived from ethylene oxide, propylene oxide or both. The reagents are mixed, usually in a solvent such as toluene or isopropanol (2-propanol), heated to approximately 70o- 85 ° C, then the catalyst is added, at a temperature where an increase of approximately 10-15 ° C is observed and the mixture is finally sampled and analyzed for the SiH groups by adding alcohol and base and measuring the evolution of hydrogen. If a volatile solvent is used, it is removed under vacuum. Polyhydrosiloxanes having the average formula M * D? D "^ 1 * are prepared in the manner known in the art For the case where M * is (CH3) 3SiO-, / 2, an alkyldisiloxane such as hexamethyldisiloxane, a polyhydrosiloxane polymer and an alkylcyclosiloxane such as octamethylcyclotetrasiloxane are reacted in the presence of a strong acid such as sulfuric acid, for the case where M * is (H) (CH3) -SiO ^ a hydridoalkyldisiloxane such as dihydrotetra ethyldisiloxane, a polyhydrosiloxane polymer, and an alkylcyclosiloxane such as octamethylcyclotetrasiloxane are reacted in the presence of a strong acid such as sulfuric acid The allyloxyalkylene polyethers are also mentioned as polyethers, they are also prepared in a manner known in the art. which optionally carries a substituent in the 1 or 2 position, is combined with ethylene oxide, propylene oxide, or both, in the presence of a catalyst b physical, to produce the desired hydroxyl group with a terminal polyether. This is typically crowned by further reaction with an alkylating or asylating agent such as methyl halide or acetic anhydride, respectively, to obtain an alkoxy or acetyl end group. Other end crowns can, of course, be used including hydrogen, alkoxy groups or alkyl or aryl groups. The surfactants of the invention are used in the manufacture of flexible polyurethane foams in the manner known in the art. In the production of the polyurethane foams using the surfactants of this invention, one or more polyols, preferably polyalkylene ether polyols, are employed by the reaction with a polyisocyanate to provide the urethane linkage. Such polyols have an average of typically 2.1 to 3.5 hydroxyl groups per molecule. Illustrative of suitable polyols as a component of the polyurethane composition are polyalkylene ether and polyester polyols. Preferred polyalkylene ether polyols include poly (alkylene oxide) polymers such as poly (ethylene oxide) polymers and (propylene oxide) polymers and copolymers with terminal hydroxyl groups derived from polyhydric compounds, including diols and triols; for example, among others, ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, pentaerythritol, glycerol, diglycerol, trimethylolpropane and similar low molecular weight polyols. In the practice of this invention, a single high molecular weight polyether polyol can be used. Also, mixtures of high molecular weight polyether polyols such as mixture of di and trifunctional materials and / or materials of different molecular weight or materials of different chemical composition can be used. Useful polyester polyols include those produced by reacting a dicarboxylic acid with an excess of a diol, for example, adipic acid with ethylene glycol or butanediol, or reacting a lactone with an excess of a diol such as caprolactone with propylene glycol. In addition to polyether and polyester polyols, master batches or premix compositions often contain a polyol polymer. The polymer polyols are used in the polyurethane foam to increase the resistance of the foam to deformation, that is to increase the properties that carry the charge of the foam. Currently, two different types of polymer polyols are used to achieve an improvement in bearing the load. The first type, described as a graft polyol, consists of a triol in which the vinyl monomers are copolymerized by grafting. Styrene and acrylonitrile are the usual monomers of choice. The second type, a polyurea modified with polyurea, is a polyol containing a polyurea dispersion formed by the reactions of a diamine and TDI. Since TDI is used in excess, some TDI can react with both polyol and polyurea. This second type of polyol polymer has a variant called polyol PIPA, which is formed by the in situ polymerization of TDI and alkanolamine in polyol. Depending on the requirements for carrying the charge, the polymer polyols may consist of 20-80% of the polyol portion of the master batch.

The polyurethane products are prepared using any of the suitable organic polyisocyanates well known in the art, including for example hexamethylene diisocyanate, diphenylene diisocyanate, toluene diisocyanate ("TDI") and 4,4'-diphenylmethane diisocyanate ("MDI "). Especially suitable are 2,4- and 2,6-TDI individually or together as their commercially available mixtures. Other suitable isocyanates are mixtures of diisocyanates commercially known as "unpurified MDI", also known as PAPI, which contains about 60% of 4,4'-diphenylmethane diisocyanate together with isomeric higher polyisocyanates and the like. Also suitable are the "prepolymers" of these polyisocyanates comprising a pre-reacted mixture of a polyisocyanate and a polyether or polyester polyol. Suitable urethane catalysts useful in the present invention are all those well known to the worker skilled in the art, including tertiary amines such as triethylene diamine, N-methylmorpholine, N-ethylmorpholine, triethylamine, tributylamine, triethanolamine, dimethylethanolamine and bisdimethylaminodiethylether and organ tin such as stannous octoate, stannous acetate, stannous oleate, stannous laurate, dibutyl tin dilaurate and other such tin salts.

Other typical agents which can be found in the polyurethane foam formulations, include chain diluents such as ethylene glycol and butanediol; crosslinkers such as diethanolamine, diisopropanolamine, triethanolamine and tripropanolamine; and especially blowing agents such as water, liquid carbon dioxide, acetone, pentane, trichloroethane, methylene chloride, trichlorofluoromethane and the like. Other additives can of course be used to impart specific properties to the foam. Examples are materials such as flame retardants, colorants, fillers and hardness modifiers. The polyurethane foams of this invention can be formed in accordance with any of the processing techniques known in the art, such as, in particular, the "one-shot" technique. According to this method, the foamed products are provided by carrying out the reaction of the polyisocyanate and the polyol simultaneously with the foaming operation. Sometimes it is convenient to add the surfactant to the reaction mixture as a premix with one or more of the blowing agent, polyol, water and catalyst components. It is understood that the relative amounts of the various components of the foam formulation are not narrowly critical. The polyol and the polyisocyanates are present in the formulation that produces foam in the main amount. The relative amounts of these two components in the mixture are well known in the art. The blowing agent, "the catalysts and the surfactant are each present in a sufficient secondary amount to foam the reaction mixture. The catalysts are present in a catalytic amount, ie that amount necessary to catalyze the reactions to produce the urethane and the urea at a reasonable speed and the surfactant is present in the amount sufficient to impart the desired properties and to stabilize the reaction foam. as for example from 0.4 to 2 pphpp. In a typical preparation, the polyol, water, surfactant, amine catalyst and optional blowing agent are mixed together, then the tin catalyst is added with stirring and finally toluene diisocyanate is mixed and the composition is allowed to foam and polymerize. The flexible polyurethane foams produced in accordance with the present invention can be used in the same area as conventional polyurethane foams. For example, the foams of the present invention can be used with advantage in the manufacture of textile interfoams, cushions, mattresses, padding, under carpets, packaging, gaskets, sealants, thermal insulators and the like.

A general formulation of polyurethane flexible plate supply foam containing the silicone surfactants according to the invention, would consist of the following components in parts by weight: Plate Provision Foam Formulation. Flexible Polyol 100 Silicone surfactant 0.4-2 Water 2-7 Auxiliary Blowing Agent 0-20 Amina-urethane catalyst 0.05-0.3 Tin-urethane catalyst 0.1-0.35 Isocyanate index 85-120 (preferably TDI) In a formulation of plate supply foam, flexible, preferred, the water level is 6-7 pphpp and the isocyanate is TDI at an index in the range of about 80 to less than 100. In the following examples, the foams were made in accordance with the following formulation and procedure: Voranol 3137 polyol 100.00 pphpp Water 6.50 pphpp amine DABCOR CS90 0.10 pphpp Tin DABCO T-10 0.32 pphpp Silicone surfactant 0.60 pphpp TDI (index 95) 67.66 pphpp pphpp = parts per hundred parts of polyol 1) For Each foam, a corrugated box is prepared that has dimensions of 35.6 x 35.6 x 35.6 centimeters (14 x 14 x 14 inches) alternatively, a polyethylene liner is prepared and inserted into a 13.3 liter (3.5 gallon) bucket. 2) A premix is prepared for each series of foams. The premix contains Voranol 3137 polyol (from Dow Chemical Company), water and DABCO CS90 amine catalyst (from Air Products and Chemicals, Inc.). 3) The premix is weighed in a 48 oz. (48 oz) paper cup and the silicone surfactant is added. 4) TDI (toluene diisocyanate) is weighed into a separate 250 ml plastic beaker. 5) DABCO T-10 catalyst is added (from Air Products and Chemical, Inc.) to the premix vessel and mixed for 10 seconds with an electronic mixer at 2000 rpm. The DABCO T-10 catalyst is a 50% dilution of stannous octoate. 6) The contents of the TDI beaker are emptied into the premix vessel and mixed immediately for 7 seconds with an electronic mixer at 2000 rpm. 7) A timer is turned on when the electronic mixer begins to mix the contents of the container containing the premix and TDI. 8) The mixture is emptied into the container that holds the container lid as close to the bottom of the container as possible to avoid splashing. 9) the remaining material in the container is weighed. 10) for each foam the following data are obtained: total increase time, total elevation height and total cure height after 16 hours. 11) The foams are cut after 16 hours. Samples of dimensions of 5.08 x 5.08 x 2.54 centimeters (2 x 2 x 1 inches) are taken from the top and bottom of the foam for determinations of airflow and density. From the lower section, 3.81 centimeters (1.5 inches) of the bottom of the foam is taken. From the upper section, 19.05 centimeters (7.5 inches) are taken from the bottom of the foam. EXAMPLE 1 The polyurethane foams are made according to the procedures described in the above, using the following surfactants. 3 foams are prepared using the boxes.

Surfactants a and b are commercial silicone surfactants, proprietary available from OSi Specialties, Inc. They were used for comparison purposes. The surfactants C and D are commercial silicone surfactants available from Th Goldschmidt AG. They were used for comparison purposes. Surfactant E is a commercially available silicone surfactant available from Air Products and Chemical, Inc. It was used for comparison purposes. The surfactant F is a silicone surfactant of the present invention, which has a siloxane backbone with x + y = 68 and a target x / y ratio of 8. Two polyether-containing substituents with end groups -C (0) CH3 are ramifications The first, present in 35% by weight of the total, has an approximate molecular weight of 3100 and an a / b ratio of 1.0. The second, present in 65% by weight of the total has an approximate molecular weight of 1250 and a relation to '/ b' of 1.0. The effectiveness of the foams prepared using each of the absurfactants is described in Table 1. In Table 1, the terms have the following meanings: "Total rise height" is the maximum height in millimeters obtained during the increase in foam.

"Complete cure height" is the maximum height in millimeters of the foam, after curing at room temperature for 16-24 hours. "% subsequent observation" = 100 x (total increase height Total cure height) Total increase height "Upper air flow" = the air flow at a back pressure of 12.7 millimeters (0.5 inches) of water in 0. 03 m3 / minute through a foam sample having the dimensions of 5.08 x 5.08 x 2.54 cm (2 x 2 x 1 inches) taken from the upper section of the foam. "Lower air flow" = the air flow at a back pressure of 12.7 millimeters (0.5 inches) of water at 0.02 m3 / minute (ft3 / minute) through a foam sample that has the dimensions of 5.08 x 5.08 x 2.54 centimeters (2 x 2 x 1 inches) taken from the bottom section of the foam. "Cell Count" = average number of cells per 2.54 linear centimeters (2 x 2 x 1 linear inches) of the foam sample.

Table 1 Table 1 shows that surfactants A, D and E give foams with low air flows and large cells. Surfactants B and C provide good air flow and cell structure, but give low height foams. Only the surfactant F of the present invention provides foam with fine cell structure, high air flow and high heights, all the required attributes of a good flexible foam. EXAMPLE 2 Polyurethane foams are prepared according to the methods described in the above, using the surfactants described in Table 2 (these foams are prepared in the cubes). Surfactants are compounds that have the general formula MD? D 'and M in which M means (CH3) 3Si01 / 2 'D means (CH3) Si02 / 2, D1 means (CH3) RSi02 / 2 > is a polyether-containing substituent selected from the group consisting of: (1) -C3H60 (C2H40) to (C3H60) bC (0) CH3 having an average molecular weight of about 3100 and (2) -C3Hg0 (C2H40) a, (C3H60) b, C (0) CH3 having an average molecular weight weight of about 1250. The values of x, y, a, b, a ', b1, the mixture average molecular weight of the R-substituents containing polyether in the surfactants and the molar ratio of total EO / PO for each of the surfactants is shown in Table 2 below.

Table 2 The use of the F-W surfactants in the foam formulation resulted in all of these surfactants producing good foams. Surfactant X, which had a total EO / PO molar ratio of 1.4, produced a foam having coarse cells and little air flow. EXAMPLE 3 The polyurethane foams are prepared according to the procedures described in the foregoing, using the surfactants described in Table 3. The surfactants have the same general formula as those employed in example 2. The values of x, y, a , b, a ', b', the average molecular weight mixture of the R-substituents containing polyether in the surfactants and the molar ratio of total EO / PO for each of the surfactants is described in Table 3 below.

Table 3 The foams are then measured for total height increase, total cure height, post observation%, upper air flow and lower air flow according to the procedures described in the following. The results of the measurements are reported in Table 4 below.

Table 4 The use of the surfactants of this invention in the foam formulation resulted in good foams, in contrast to the surfactants A'-F ', which either compressed or had poor foam characteristics.

Claims (12)

1. CLAIMS 1. In a method for preparing a polyurethane plate supply foam, flexible by the reaction of a polyol, an organic diisocyanate, and water in the presence of at least one urethane catalyst, a siloxane-oxyalkylene copolymer surfactant and optionally another blowing agent, characterized in that the siloxane-oxyalkylene copolymer surfactant has the average formula MD? D 'and "wherein M represents (CH3) 3 Si01 / 2 or
2. R (CH3) 2Si01 2, D represents (CH3) 2Si02 / 2, D 'represents
3. (CH3) RSi02 2, the value of x + y is 48 to 220 and the ratio x / y is 5 to 15 inclusive in which the previous formula for
4. M and D1, R is a polyether containing a substituent selected from the group consisting of: (1) -CNH2nO (C2H40) to (C3H60) bR 'portions having an average molecular weight in the range of 2300-3400 and wherein n is 3-4, the ratio a / b is 0.5 to 1.3 inclusive, R1 represents hydrogen, an alkyl group of 1-4 carbon atoms or -C (0) CH3; and (2) the portions - Cn, H2n, 0 (C2H40) a, (C3H60) b, R 'which have average molecular weight in the range of 750-1400 and in which n' is 3-4, a 'is a number such that the ethylene oxide residues constitute 30-100% by weight of the alkylene oxide residues of the polyether, b1 is a number such that the residues of propylene oxide constitute 0-70% by weight of the alkylene oxide residues of the polyether, R 'represents hydrogen, an alkyl group of 1-4 carbon atoms or -C (0) CH3 and average mixture of the molecular weight of the total polyether-containing R substituents in the surfactants is in the range of 1500-2200 and the total EO / PO molar ratio is in the range of 0.65-1.2. 2. The method according to claim 1, characterized in that the value of x + y is about 68, the ratio x / y is about 8, and R comprises a first substituent containing polyether at 35% by weight, about 3100 average molecular weight weight and an a / b ratio of 1.0 and a second substituent containing polyether at 65% by weight, of about 1250 average molecular weight and an a '/ b' ratio of 1.0. 3. The method according to claim 1, characterized in that x has a value of 44 to 63 e and has a value of 5.5 to 12.
5. 5. 4. The method according to claim 1, characterized in that x has a value of 60 to 62 e and has a value of 7 to 8. The method according to claim 1, characterized in that R 'is -C (0) ) CH3.
6. 6. The method according to claim 2, characterized in that R 'is -C (0) CH3.
7. 7. The method in accordance with the claim 3, characterized in that R 'is -C (0) CH3 >
8. 8. The method of compliance with the claim 4, characterized in that R "is -C (0) CH3>
9. 9. The method according to the claim 1, characterized in that (2) is a portion -C3Hg (C2H40) to (C3HgO) J-JR 'containing about 43% by weight of the ethylene oxide residue and having an average weight of the molecular weights of about 1250.
10. 10. The method of compliance with the claim 9, characterized in that R * is -C (0) CH3. The method according to claim 1, characterized in that the average weight of the molecular weight of the mixture of the substituents R containing polyether in the surfactant is 1650-1900. 12. The method according to claim 1, characterized in that the total EO / PO molar ratio is 1.0. SUMMARY This invention relates to a method for preparing a polyurethane plate supply foam, flexible by the reaction of a polyol, an organic diisocyanate and water in the presence of at least one urethane catalyst, a siloxane copolymer surfactant, and oxyalkylene and optionally, another blowing agent, where the surfactant has the average formula MD? D '^ I where M is (CH3) 3Si01 / 2 or R (CH3) 2Si01 / 2, D is (CH3) 2Si02 / 2, D 'is (CH3) RSi02 2, and the value of x + y is from 48 to 220, the ratio x / y is from 5 to 15 inclusive, R is a polyether-containing substituent selected from the group consisting of (1) a -CNH2nO (C2H40) group ( C3HgO) J-JR 'which have an average molecular weight in the range of 2300-3400 and in which n is 3-4, the ratio a / b is 0.5 to 1.3 inclusive, R' represents hydrogen, a group alkyl of 1-4 carbon atoms or -C (0) CH3 and (2) a group -Cn, H2n, O (C2H40) a, (C-jHgO) b, R 'having average weight of molecular weights in the range of 750-1400 and where n 'is 3-4, a' is such a number that the ethylene oxide residues constitute 30-100% by weight of the alkylene oxide residues of the polyether, d 'is a number such that the residues of propylene oxide constitute 0-70% by weight of the alkylene oxide residues of the polyether, R1 represents hydrogen, an alkyl group of 1-4 carbon atoms or -C (0) CH3 and the mixture Average molecular weight of the substituents R which contain total polyether in the surfactant, is in the range of 1500-2200 and the molar ratio of EO / PO is in the range of 0.65-1.2.