DE1694646A1 - Polyurethane foams and processes for their manufacture - Google Patents

Description

Polyurethane foams and processes for their manufacture. Manufacture of polyurethane foams using surfactants as Stabilizers is well known.

These stabilizers were mainly designed to protect hydroxyl groups Satisfactory polyethers with polyisocyanates according to the one-step process Way to foam to corresponding polyurethane foams. As stabilizers Above all, silicone stabilizers have proven themselves, especially those that are long-chain Have polyether groups in the molecule.

In this way it is possible to obtain stable polyether urethane foams the one-step process that have improved properties and the corresponding in maccher terms Polyester foams are superior.

It has been found that the manufacture of polyether polyurethane foams advantageous foam stabilizers based on polysiloxane-polyoxyalkylene as a result their incompatibility in the production of corresponding polyester polyurethane foams are not suitable. Organic silicon compounds such as silanes and siloxanes, the do not contain any? olyether segments, are completely incompatible with polyester-polyurethane formulations and migrate to the surface of the products obtained, e.g. Foams, from. Polyether segments Silicones containing them can be dispersed into polyester polyurethane foam formulations but they too often migrate to the surface after a very short time of the reaction mixture are therefore not uniform for the reduction of the Surface tension during the foaming process and thus for relief cell formation available during foaming.

Surprisingly, it has now been found. da # organic silicone compounds, the plural. of ester bonds are excellent as stabilizers Suitable for the production of polyurethane foams based on polyesters They are shown to be very compatible with both the reaction components ale also with the foamable reaction mixture and unfold dementspre @@@@ e at ashr high surface-active effect. On this @ @@ @ it is n @ n possible @. even the advantages obtained with the polyether polyurethane foams also apply to polyester polyurethane foams su transferred, i.e. polyurethane foams with an improved pore size and to produce with improved pore distribution. The process products thus obtained are characterized by a very uniform pore size and associated with it excellent physical properties.

The present invention thus provides a process for the production of polyurethane foams based on polyisocyanates, polyhydroxyl compounds, water and / or organic blowing agents and silicone foam stabilizers, characterized in that the silicone shawa stabilizers are polyester silicones of the formulas YO- (polyester) - (Si-RR "'-O) - (polyester) -Y m R" (4-x) -Si - [(O-Si-RR "') m- (polyester) OY] x R (4-x) -Si - [(polyester) -OY] x GO- (Si-RR "'-O) - (polyester) - (O-si-RR"') OG 'mm R "" (4 -z) -C- [R "'- (polyester) - (O-Si-RR"') m-OG7z R "" (4-z) -C- [R "'- (O-Si-RR"') m- (polyester) -OG7z used, in which R, R' and R "represent an optionally substituted aliphatic or aromatic radical or fluorine, provided that only one of the radicals R, R 'and R" represents fluorine, R "'denotes an optionally substituted aliphatic or aromatic radical, R""is an optionally substituted aliphatic or aromatic radical or halogen, Y denotes an optionally substituted saturated or unsaturated aliphatic or aromatic hydroxyaliphatic, hydroxyaromatic, mercaptoaliphatic, mercaptoaromatic, carboryaliphatic, aminoboxyaromatic or aminoaromatic radical or hydrogen, G and G1 correspond to Y and Si (R) 3 and Si (R) 2F, Q i st an ether or ester, Q 'is an ester, m is an integer from 3 - 50, n and R are an integer from 1 - 100, z is an integer from 1 - 4 and x is an integer from 0-4.

The invention also relates to polyurethane foams according to can be obtained using this method.

The polyester silicones to be used according to the invention melt in usually below 1500 and are preferably liquids at room temperature. she can both no reactive end groups and reactive end groups such as reactive Have hydrogen atoms. As a precaution, they have reactive groups such as hydroxyl, Amino, carboxyl or mercapto groups. In this way foams are obtained with particularly good compression set. The radicals R, R ', R ", R" 1 and R "" in The formulas can be any optionally substituted aliphatic or aromatic Represent residues, e.g. B. residues such as methyl, ethyl, n- and isopropyl, butyl, tert-broth, Pentyl, Hexyl, Heptyl, Octyl, Dodecyl, Heptadecyl, Eisocyl, Cyclopropyl, Cyclobutyl, Cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclopentadecyl, phenyl, α- and ß-naphthyl, ß-phenyl ether, O-, m- and p-tolyl, 2,3-, 2,4-, 2,5- and 2,6-xylyl, 1-ethylß-naphthyl. pirn can also represent a halogen atom such as fluorine, chlorine, bromine or iodine. EUr Y Any saturated or unsaturated aliphatic is used in the formulas mentioned or aromatic radical in question, e.g. Alkylene radicals such as ethenyl, propenyl, butenyl, Hexenyl, octenyl, dodecenyl, pentadecenyl, octadecenyl, Eisocenylreste, Cycloalkenylreste such as Cyclohesyläthenyl- or Cycloheptylpropenylreste. Y can also be any hydroxyaliphatic, hydroxyaromatic, mercaptoaliphatic, mercaptoaromatic, carboxyaliphatic, carboxyaromatic, aminoaliphatic and aminoaromatic Represent remainder, e.g. B. a hydroxymethyl, hydroxyethyl, hydroxycyclohexyl, Hydroxyphenyl, 3-ethyl-5-hydroxyphenyl, mercaptophenyl, mercaptodecyl, aminomethyl, Aminoethyl, 4-aminocyclohexyl, 7-aminonaphthyl and 4-ethyl-8-aminonaphthyl radical. The polyester content of the polyester silicone to be used according to the invention is through embodies any polyester of aliphatic or aromatic nature. The radical Q is preferably a polyester.

For the production of the silicone compound to be used according to the invention Any Ilydroryl polyester, including lactone polyester, can therefore be used, e.g. the reaction products of polycarboxylic acids with polyhydric alcohols.

As a polycarboxylic acid, e.g. oxalic acid, malonic acid, succinic acid, Glutaric acid, adipic acid, pimelic acid, azealic acid, sebacic acid, malelic acid, Fumaric acid, isophthalic acid, terephthalic acid, mellitic acid, trimellitic acid, pyromellitic acid and hexahydrophthalic acid can be used, while the polyhydric alcohols e.g. Ethylene glycol, propylene glycol (1,3) and - (1,2), hexanediol (1,6), glycerine, trimethylolpropane, Hydroquinone come into question. Instead of hydroxyl polyesters can be used for the production there are polyester silicones to be used according to the invention also polyester amides, e.g. based on polycarboxylic acids and amino alcohols, come into question.

Both the already mentioned radicals R, R ', R ", R"', R "", Y, G, G 'and Q and the polyester or polyester amide segments of the polyester silicones according to the invention can have substituents. As substituents there are halogen atoms, for example fluorine, chlorine, bromine and iodine, nitro groups, alkoxy groups, for example methoxy, ethoxy, propoxy, butoxy groups, carboxyalkyl groups such as methory, carbethyric groups, dialkylamino groups such as dimethylamino, dipropyiamino carbon groups and mercaptocylans -, thiocarbonyl and phosphorus-containing radicals as well as silyl and siloxy groups in question. The following compounds are listed as examples of polyester silicones to be used according to the invention: The polyester silicones to be used according to the invention are added to the foamable reaction mixture in any desired manner and using any desired apparatus, for example those described in American Reissue Patent No. 24,514. It is possible, for example, to first mix the polyester silicone with the polyester to be used which contains hydroxyl groups and then to allow the reaction between the polyol and the polyisocyanate to take place. But one can also proceed in other suitable ways.

The polyester silicones to be used according to the invention are in the Usually in an amount of 0.01-5% by weight, based on the weight of the other components the polyurethane formulation, but preferably in an amount of 0.2-2.0% by weight, used. The production of the stable polyurethane foams according to the invention takes place according to the usual working methods.

Regarding the details of the polyurethane foam manufacturing technology reference is made to the very extensive patent and technical literature, e.g. to American Patent No. 2,910,445, and also to "Polyurethanes", Bernhard A. Dombrow, Reinhol Publishing Corporation, New York (1957), further on "Polyurethanes, A Versatile Synthetic for a Dynamic Area ", Polyurethane Associatefs (1956), on to Urethane Applications Laboratory Memorandum No. 60, April 28, 1961, Wyandotte ChemLcals Corporation, Reaearch Division; "Polynrethane Foam Catalysts", Technical Bulletin, No. B6-R4, June 160, Armor Industrial Chemicat Company of "Dabco", Data Bulletin No. 4, July 20, 1959, Houdry Proceas Corporation.

Any organic products can be used for the production of the process products Polyisocyanates Ln question, .B. nor that in Canadian Patent 698,638 are listed, in addition, e.g. tetramethylene dilsocyanate, hexamethylene dilsocyanate - (@, @), 1,5- and 1,4-phenylene diisocyanate, cyclohexane-1,4-diisocyanate, 2,4 and 2,6-tolylene diisocyanate as well as lively mixtures of these isomers, chlorine-substituted toluene diisocyanates, 1,4-xylylene secyanate, 4,4'-diphenylmethanedilsocyanate 1,5-naphthylene diisocyanate, 4,4 ', 4 "-triphenylmethane triisocyanate, polyaryl-polyalkylene-polyisocyanates such as them produced by aniline-formaldehyde condensation and subsequent phosgenation are, carbodiimide-containing isocyanates, trimerized polyisocyanates. It is also possible, these isocyanates mixed with one another and in masked form, z. B. with phenols or oximes to use.

The process products are made by reacting the polyisocyanates with Polyhydroxyl compounds produced. The hydroxyl polyesters come from the production of the polyester silicones to be used according to the invention has already been mentioned Kind in question, i.e. those based on polycarboxylic acids and polyhydric alcohols or those based on polylactones. As polyhydroxyl compounds to be used according to the invention Hydroxyl polyethers can also be used, as they are produced by the polymerization of alkylene oxides, z.3. Ethylene or propylene oxide or tetrahydrofuran or by addition of alkylenozides to starter molecules, e.g. to glycerine, trimethylolpropane, cane sugar or ethylenediamine can be made in question. Basically everyone comes for the trial According to the invention, hydroxyl polyethers known so far for the production of polyurethane foams into consideration, d .. z. B. also those obtained by the addition of several alkylene oxides can be produced at the same time or together with starter molecules. According to the invention However, hydroxyl polyesters are preferably used as polyhydroxyl compounds.

The products of the process are produced with the help of any blowing agent obtain. If water is used as a propellant, it must also be used for the reaction additional amounts corresponding to the water and the evolution of carbon dioxide are used on isocyanates. Instead of water, however, low-boiling points can also be used Hydrocarbons such as pentane, hexane or pentene or halogenated hydrocarbons such as dichlorodifluoromethane, dichlorodifluoroethane or trichlorofluoromethane or methylene chloride can be used. Azo compounds such as Azohexahydrobensodinitril can be used as Find propellants use.

For the production of the polyurethane foams according to the invention can if necessary, suitable catalysts can also be used, e.g. those described in American patents 3,201,372 and 3,194,773, respectively. It it is also possible to use other additives in foam production, such as dyes or fillers to be used.

The foams produced according to the invention are hard, semi-hard or softer nature. They can be used in the upholstery industry as an insulating material in the Construction industry or z. B. can be used as shock protection in the automotive industry.

Production of the polyester silicones to be used according to the invention 0 .A) 265 parts of G2H5O # CH2CH2-Si (CH3) - (OC2H5) 2 are hydrolyzed with water in the presence of 10 parts (cH3) 3-SiCl. 950 parts of the siloxane obtained in this way are then mixed with 1000 parts of a polyester having a hydroxyl number of 112 obtained by reacting adipic acid with diethylene glycol and, in the presence of catalytic amounts of trifluoroacetic acid, to form the polyester silicone implemented.

Polyester silicones of this type can generally be prepared by hydrolysis of compounds of the formulas 0 0 RO # (CH2) nSi (CH3) (OR ') 2 and #CO (CH2) nSi (CH3) (OR') 2 in which R and R 'are aliphatic or represent aromatic residues. So z. B. such polyester silicones are obtained by hydrolysis of the compound C2H5OCCH2CH2Si (CH3) (OC2H5) 2 with water in the presence of compound (CH3) 3Sicl, initially a silorane of the formula arises, in which n is an integer from @ - 100, which then softens with a monofunctional or difunctional polyester and / or polyether in the presence of a catalyst to form a compound of the general formula is implemented.

0 B) 23O parts by weight of the compound CH3 # O (CH2) 3-Si (CH3) (OC2H5) 2 are mixed with water in the presence of 10 parts by weight (CH3) 3SiCl to form a silorane of the formula hydrolyzed. 1260 parts by weight of the siloxane thus obtained are reacted with 500 parts by weight of a polyester obtained by reacting adipic acid and diethylene glycol with a hydroxyl number of 112 and an acid number of less than 1.5 in the presence of catalytic amounts of trifluoroacetic acid. A polyester silicone of the formula is obtained Polyester silicones of this type can generally be prepared by reacting a polyester with a siloxane which is obtained by hydrolysis of a siloxane, similar to those listed under A), in the presence of a catalytic amount of a suitable catalyst.

C) 2 moles of one obtained by reacting phthalic acid, adipic acid and diethylene glycol The obtained polyesters having a hydroxyl number of 90 are dissolved in 2 liters of xylene. To this Solution is 1 mole of a polysilorane of the formula RO [Si (CH3) 2O] nR, which is controlled by Hydrolysis of a corresponding diorganodiohlorosilane or diorganodialkoxysilane made in alcohol is added. A Dean Stark trap is created with the Reaction flask connected while nan the reaction mixture in the presence of 5 ml concentrated sulfuric acid for 10 hours or up to 2 moles of alcohol in the trap are refluxed. The reaction mixture is then made with sodium bicarbonate neutralized, filtered and subjected to a vacuum of 1u mm Hg at 1100 until most of the iylene is removed. The temperature is then increased to 1600, until all volatile components are eliminated.

A polyester silicone is obtained.

Polyester silicones of this type are e.g. Polysiloxane with a suitable polyester at 1500 or higher in the presence of a Catalyst such as tritluoroacetic acid under nitrogen and with removal of the split off Alkanols, neutralization and subsequent filtration. D) 1 mole of phenol is added to 10 moles of (CH3) 2Si (OC2H5) 2 in the presence of t g of zinc acetate. The reaction mixture is refluxed for 6 hours, towards the end of this Time 1 mole of ethanol was distilled off from the reaction mixture.

A phenol-endblocked silane of the formula is obtained which is mixed with (Ch3) 2Si (OC2H5) 2. This mixture is treated with 4 mol of water at 900 for 2 hours and then heated to 120 ° until all of the ethanol has distilled off. 98% of the theoretical amount of ethanol is obtained. The ethoxy content of the disilozane obtained in this way is 5 5, corresponding to a molecular weight of about 850.

400 parts by weight of a polyester with a molecular weight of 800, the produced by the reaction of ethylene glycol and sebacic acid mixed with 425 parts by weight of the ethoxylated polysiloxane, and 1 part by weight Trifluoric acid and 2 liters of toluene are added. The reaction mixture is heated under reflux until 0.5 mol of ethanol from the reaction mixture are deposited (approx. 8 hours The trifluoroacetic acid is mixed with sodium bicarbonate, neutralized, the solution is filtered and toluene is added under reduced pressure removed. The temperature of the reaction mixture is then increased to 140oCX 1 mm Hg to remove all volatiles. Ao eSn polyester silicone is obtained as a viscous, slightly yellowish oil, which has a molecular weight of about 1600.

Polyester silicones of this type are preferably prepared by reacting a suitable polyester with a suitable silorane at reflux temperature in the presence of a catalytic amount of a catalyst. E) To 470 parts by weight and 1330 parts by weight of a mixed cyclic dimethylsiloxane, which contains approx. 22% tetrameric, approx. 20 ffi pentameric and approx. 56% higher cyclic polymers, 5 parts by weight potassium hydroxide are added in a reaction vessel with stirring. The reaction temperature is maintained at 160 ° for 3 hours, operating under nitrogen. The reaction vessel is then brought to a vacuum of 1 mm Hg in order to separate off 12-15 ffi of volatile siloxanes. The residue obtained is a stone-free oil with a molecular weight of 1600.

This residue is then mixed with 3 liters of toluene and 1300 parts by weight of a linear polyester that is produced by the reaction of glutaric acid and 1,4-butanediol has been prepared and has a hydroxyl number of 120, and 1 g of trifluoroacetic acid are added. The reaction mixture is refluxed until whole Water from the reaction mixture has separated out in a water separator. When the water separation has ended, the reaction mixture is under for so long Heated to reflux until the theoretical amount of methanol has split off (approx. 10 hours). Add 0.1 mol of sodium bicarbonate to the reaction mixture to neutralize Trifluoroacetic acid has been added, the Mix still Heated for 1 hour and filtered. The reaction mixture is then released from the solvent freed and the temperature is increased to 1600 under a vacuum of 1 mm Hg to remove all volatile components. The viscous oil obtained is clear and amber in color and shows a 3 Rookfield viscosity of 10,000 cps at 25 ° C.

Polyester silicones of this type are preferably produced by reacting alkosysiloxanes with mixed cyclic siloxanes with basic catalysis. The siloxanes thus obtained are then reacted under reflux conditions with a desired polyester in the presence of a catalytic amount of a suitable catalyst. However, it is also possible and often preferred, polyester silicones by equilibrating a silicone mixture, for example of or linear or cyclic dimethylsiloxanes with the desired polyester in the presence of a suitable catalyst such as potassium hydride at temperatures above 120 ° C.

F) 2 moles of a polydimethylsiloxane of molecular weight 830 and the formula are added to 1 mole of a polyester having a molecular weight of 1300, which has been prepared by reacting adipic acid and ethylene glycol, in the presence of 1 g of trifluoroacetic acid. The reaction mixture is refluxed for 3 hours in 3 liters of toluene and with the application of a Dean-Stark trap, in order to remove the methanol which forms. The acidic catalyst is then neutralized with sodium bicarbonate.

The mixture is filtered and toluene is blended out of the reaction distilled off. You get a berns. tein-color oil, adjusted to 1500/1 mm / Hg for 2 hours is heated to remove volatile components. The reaction product is a clear, viscous resin with a viscosity of 1600 cps at 230C.

Polyester silicones of this type can generally by reacting 2 moles of an end-blocked siloxane with one mole of a suitable polyester below Reflux conditions in the presence of a catalytic amount of a suitable catalyst are produced G) 1 mol of a trifunctional polyester, which by reaction of glycerol and 1, 4-butanediol with adipic acid and one Having a hydroxyl number of 47 is below Reflux conditions 10 Hours with 1250 parts by weight (3 moles) of a linear dimethylsiloxane terminated Methoxy groups (methoxy content 15%) in 4 liters of toluene in the presence of 1 part by weight Trifluoroacetic acid reacted.

The trifluoroacetic acid is then treated with 1 part by weight of sodium bicarbonate neutralized and the reaction mixture is refluxed for a further hour and then filtered. Toluene is drawn off and the remaining volatile Portions are removed at 1500/1 mm fig. A pale amber color is obtained Oil with a Brookfield viscosity of about 1400 at 23 ° C.

Polyester silicones of this type are generally preferred by Implementation of a suitable branched polyester with a linear alkoxy end-blocked Siloxane produced.

H) To 1500 parts by weight of a linear polyester with a hydroxyl number of 90, which has been prepared by reacting diethylene glycol and adipic acid, in 4 liters of toluene become 4- / 0 g 0; -); - - 0 - OH OH - 3 OH 0 CH3 ) t and 1 part by weight of trioluoroacetic acid added. The reaction mixture is heated using a Dean-Stark trap and under nitrogen until 3 mol of methanol have separated out (approx. 4 hours). The solution is then neutralized with 1 g of sodium bicarbonate and the mixture is refluxed at 150 ° for 1 hour and filtered hot. The resulting viscous amber oil is then heated at 1500/1 mm Hg for 1 hour to remove residual methanol. The viscosity of the oil obtained is 7000 cps at 23 ° C.

Polyester silicones of this type are generally preferred by reaction a suitable polyester with a siloxane under reflux conditions in the presence a catalytic amount of a suitable catalyst.

Example 1: 100 parts by weight of one obtained by reacting 1 mole of adipic acid and 1 mole of diethylene glycol and 1/30 mole of trimethylolpropane made polyester of molecular weight 2000, viscosity of 1000-1200 cps at 730 and one Hydroxyl number of about 60, 25 parts by weight of toluene-2,4-diisocyanate, 3 parts by weight of an activator mixture consisting of 4 parts by weight of diethanolamine adipate, 2 parts by weight of the polyester silicone according to A) and 1.2 parts by weight of water are commercially available Foaming machine, as described e.g. in the American patent specification 24 514 is described, mixed, given in egg form and foamed. You get one soft flexible foam with a density of 65-75 kg / m3. The cell structure is flawless and the pore size is uniform.

Example 2: 100 parts by weight of a molecular weight polyester 2900 and a hydroxyl number of 50, which is obtained by the condensation of adipic acid1 dietloylene glycol and trimethylolpropane has been produced, 2 parts by weight of N-ethylmorpholine, 1.5 parts by weight of the polyester silicone produced according to B), Jsb parts by weight Water and 45 parts by weight of an isomer mixture consisting of 80% 2,4- and 20% 2,6-toluene diisocyanate are in a foaming apparatus according to the example 1 mixed and foamed. The foam thus retained has a uniform cell structure, shows no closed cells and has a high compression set. example 3: 100 parts by weight of a polyester having a molecular weight of 2,600 and a hydroxyl number of 57, which is produced by the condensation of adipic acid, diethylene glycol and trimethylolpropane has been prepared, 2 parts by weight of N-ethylmorpholine, 1.5 parts by weight of the Polyester silicones according to C), 3.6 parts by weight of water and 46 parts by weight of one Isomer mixture consisting of 65 parts by weight of 2,4-tolylene and 35 parts by weight Toluylene-2,6-diisocyanate are in a foaming apparatus according to Example 1 mixed and foamed. A polyurethane foam with a single density is obtained of 1.6, which has uniform cell structure and good physical properties.

Example 4: 25 parts by weight of N, N, N ', N'-tetrakis (2-hydroxypropyl) ethylenediamine, 1 part by weight of tetramethylbutanediamine, 35 parts by weight of trichlorofluoromethane, 78 Parts by weight of crude 4,4'-diphenylmethane diisocyanate and 2 parts by weight of a silicone according to D) are mixed together and poured into a mold.

A hard polyurethane foam with a uniform cell structure is obtained and excellent physical properties.

Example 5: 75 parts by weight of a polyvalent hydroxyl group Polyalylene ether made from sorbitol and propylene oxide and a Molecular weight of 650 and has a hydroxyl number of 562, are with 70 weight points of an isomer mixture consisting of 80% 2,4- and 20% 2,6-tolylene diisocyanate with 0.2 parts by weight of tin octoate, with 0.9 parts by weight N, N, N ', N'-Tetramethyl-1,3-butanediamine, with a part by weight of that prepared according to # E) Silicones and with 20 parts by weight of frichlorofluoromethane in an illsch machine, as it is offeaoart in the American Reissue Patent Publication 24 514, mixed. The resulting mixture is placed in a cardboard box, and with evolution of gas a polyurethane foam is created. This foam has a uniform cell structure and good physical properties.

Example 6: 100 parts by weight of a reaction of 1 mole of adipic acid, 1 mol of diethylene glycol and 1.30 mol of irimethylolpropane produced polyester from Molecular weight 2000 and the O @ -Sahl 50, 25 parts by weight of 4-isopropyltoluylene-2,6-diisocyanate and 3 parts by weight of an activator mixture consisting of 4 parts by weight of diethanolamine adipate catalyst, 2 parts by weight of the polyester silicone according to # F) and 1.2 parts by weight of water in a commercially available foaming machine, such as that used in the American Reissue patent specification 24 514 is described, foamed. You get a flexible one Foam with a uniform cell structure that does not show any tendency to shrink.

Example 7: 100 parts by weight of a condensation of adipic acid, lhihalic anhydride, trimethylolpropane and oleic acid produced polyesters of The hydroxyl number is 350 and the acid number is about 2 with 85 parts by weight of a mixture of isomers from 80 toluene-2,4- and 20 toluene-2,6-diisocyanate and 7 parts by weight Water, 7.5 parts by weight of an activator mixture consisting of 3 styles by weight N-diethyl-ethylamine phenyl ether, 0.5 part by weight of permethylated diethylenetriamine and 4 parts by weight of a silicone according to # G) mixed and foamed. The received Polyurethane foam in turn has a uniform cell structure, shows no shrinkage, not even when heated in water, and is thermal up to temperatures of 140 ° stahil.

Example 8: 100 parts by weight of a reaction of N-lhenyldiethanolamine, Trimethylolpropau and adipic acid mountainous polyester with a functionality of 2.2 is with 26 parts by weight 4,4'-Diphenylmethandiisccyanat in the presence of 1 part by weight of the silica prepared in accordance with) s @ such as 1.7 parts by weight of water and 1 part by weight of N-methylmcrpholine mixed. The foamable reaction mixture is poured into an open form and foamed, after a rise time of 3 minutes a foam with a density of 0.08 g / cm3, which is a uniform Cell structure, stent.

Example 9: 100 parts by weight of a mixture consisting of 90% below a polyester obtained by reacting diethylene glycol, trimethylolpropane and Adipic acid has been produced and has an OH number of 60 and 10% from a polyester, which is produced by the reaction of trimethylolpropane, a polyethylene glycol with a molecular weight of 400 and adipic acid and one Has an OH number of 50, 45 parts by weight of toluene diisocyanate become one Pre-adduct implemented.

This pre-adduct is converted into a polyurethane foam, in which 3 parts by weight of the polyester silicone according to # E), 1.5 parts by weight of N-ethylmorpholine and 3.3 parts by weight of water are added and the foamable reaction mixture up to be stirred at the beginning of the foaming process. The reaction mixture is then in given a shape in which it foams.

This process gives a foam with flawless Cell structure and uniform cell size.

Example 10: 50 parts by weight of a diethylene glycol / pentaerythritol adipate copolymer 16 parts by weight of hexamettiylene diisocyanate and 1.5 parts by weight of di- (ß-diethylamine ethyl) adipate, one part by weight of the polyester silicone produced according to E) and 1 part by weight Stirring water. The liquid material obtained is introduced into a mold and left to stand at room temperature. A highly elastic, foam-like one is obtained Material with uniform cell structure and uniform pore size Even with repetition this experiment using the silicone according to D) is a highly elastic, obtained foam-like product with uniform cell structure.

Claims (1)

Patent claims: 1. Process for the production of polyurethane foams based on polyisocyanates, polyhydroxyl compounds, water and / or organic blowing agents and silicone foam stabilizers, characterized in that the foam stabilizers used are polyester silicones of the formulas YO- (polyester) - (Si-RR "'- O) m- (polyester) -YR" (4-x) -Si - [(O-Si-RR "') m- (polyester) -OY] x R (4-x) -Si - [(polyester) -OY] x GO- (Si-RR "'- O) m- (polyester) - (O-Si-RR"') m-OG 'R "" (4-z) -CR "'- (polyester) - (O-Si-RR"') m-OG] z R "" (4-z) -C- [R "'- (O-Si-RR "') m- (polyester) -OG] z is used in which R, R' and R" denote an optionally substituted aliphatic or aromatic radical or fluorine, with the proviso that only one of the radicals, R, R 'and R "Represents fluorine, R"'means an optionally substituted aliphatic or aromatic radical, R "" is an optionally substituted aliphatic or aromatic radical or halogen, Y means an optionally substituted saturated or unsaturated aliphatic or aromatic hydroxyaliphatic, hydroxyaromatic, mercaptoaliphatic, mercaptoaromatic, carboxyaliphatic , carboryaromatic, aminoaliphatic or aminoaromatic radical or hydrogen, G and Gx correspond to Y and Si (R) 3 and si (R) 2F, Q is an ether or ester, 2 'is an ester, m is an integer from 3 to 50, n and R are an integer from 1 to 100, z is an integer from 1 to ir and r is an integer from 0 to 4. Polyurethane foams obtainable by the process according to claim 1.