Composition of a crosslinking agent for polyurethane foam and its use in polyurethane compositions and foams

Abstract

The invention relates to a crosslinking agent composition comprising a sugar alcohol, urea and further glycol and glycerin. The invention also relates to the use of the crosslinking agent composition for the production of polyurethane compositions, preferably for the production of flexible polyurethane foams. The invention also relates to a polyurethane composition comprising polyurethane and a crosslinking agent composition, preferably in an amount of not more than 3% by weight. The invention also relates to a polyurethane foam obtained by reacting and foaming the polyurethane composition.

Description

[0001] Composition of a crosslinking agent for polyurethane foam and its use in polyurethane compositions and foams

[0002] The invention relates to a composition of a crosslinking agent for a flexible polyurethane foam comprising a sugar alcohol, water and a nitrogen-containing compound, wherein the polyurethane foam is preferably high-resilient or viscoelastic. The invention also relates to the use of such a composition in a polyurethane composition for producing such foams.

[0003] Polyurethane foams are used in a wide variety of applications, from cushioning (such as mattresses, pillows, and seat cushions) to packaging, thermal insulation, and medical applications. Polyurethanes can be tailored to specific applications by selecting the raw materials from which the polymer is made.

[0004] One type of specialized flexible foam is HR foam (high resilience). They are characterised by a much higher resilience than standard foams. Another group of flexible foams are VE foams (viscoelastic), characterised by shape memory and low resilience. A common feature of HR and VE foams are production problems that may occur in the case of continuous production. They manifest themselves in the shape deformation of the block after the foam has been cured. This type of defect is affected by the non-uniformity of the foam properties in the cross-section, in particular the differences in hardness and density.

[0005] In HR foams, the problem could be solved by using DBTDL (dibutyltin dilaurate), but the above substance is highly harmful, which is why in most countries its use is being abandoned or banned altogether.

[0006] Considering the above problems and limitations, it was crucial to develop an additive that would allow avoiding the above production problems while not being harmful to people and the environment. Sugar polyol additives are the most compromise solution. The vast majority of such raw materials are safe for people and the environment. In terms of chemistry, they contain many reactive OH groups, which allow for proper cross-linking of the foam and, indirectly, stabilization of the block.

[0007] Maltitol is disclosed as a component for the production of polyurethane systems. It can be obtained by hydrolysis of starch. It is used as a starter for the production of polyols, and has so far been mainly used for the production of rigid foams. However, in the last decade there have been publications disclosing sugar alcohols as cross-linking agents in foams, including flexible foams.

[0008] Document EP2762509 B1 relates to a polyurethane system, preferably free of a tin catalyst, obtained by using a composition which comprises compounds comprising a 5- or 6-membered ring, e.g. maltitol, sorbitan, sorbitol and others, and a glycol, wherein the mass ratio of the ring-containing compound to glycols is in the range of 1 :3 to 3:1 , and the polyurethane system comprises from 0.01 to 5 wt.% of structural units based on ring compounds. The above system does not disclose the combination of maltitol and urea, which is crucial in the solution according to the present invention.

[0009] Document US2022017680A1 relates to a method for producing foams using a nitrogen- free crosslinking agent with a hydroxyl number above 1000 mgKOH / g and a tin catalyst. Additionally, the description lacks examples using glycerol, it is only mentioned as possible to use. The application presents diglycerol and triglycerol, the difference in the composition of the composition according to the invention is significant. Based on this description, it is not possible to conclude on the properties of foams obtained using the disclosed crosslinking agent and glycerol.

[0010] Document WO2021215309A1 concerns the use of sugar alcohols (including maltitol) as crosslinking agents in molded polyurethane foams. However, the presented formulations use MDI isocyanates for molded foams, which do not have the problem of poor block shape. In addition, for storage reasons, monosaccharides such as sorbitol are preferred.

[0011] Document JP2020100694A concerns the production of polyurethane for coating applications using polyols based on highly functional raw materials. In the examples, DBTDL was used as a catalyst. The above document does not directly concern the use of raw materials such as maltitol and, due to its nature, does not describe and does not solve the problem of poor block shape in continuous foam production.

[0012] Document WO2020129806A1 concerns the use of sugar alcohols as cross-linking agents in molded polyurethane foams. The foams presented use, similarly to the previous document, MDI as an isocyanate for molded foams, in which there is no problem of the bad shape of the block. The document also lacks information about the use of maltitol.

[0013] Document JPWO2013021871A1 concerns the production of flexible polyurethane foam using a tin catalyst. The document describes substances such as sorbitol, glycerin, trimethylol propane or sucrose as crosslinking agents. There is no information on the use of urea or maltitol. In the document, tests were carried out for molded foam (in a closed mold) and "slabstock" (in an open mold), but there is no information whether the invention has been confirmed in the production of continuous foam on an industrial scale.

[0014] In addition, the document US2022204681A1 points out the problem of foam deformation, proposing a combination of organic derivatives of urea and amines as a solution to this problem. However, the maximum value of the deformation effect ("cold flow"), calculated as the final (final foam height / initial foam height) * 100%, was 87.5% or less. The document also compared the effect of other standard crosslinking agents and showed that it reaches up to 27%, which means that from the initial height value of 15 cm the foam deformed to the final 4 cm.

[0015] The aim of the invention was to develop a crosslinking agent for flexible HR and VE type polyurethane foams, which is stable and contains ingredients that are safe for humans, such as sugar alcohols. The present invention is used in block foam and enables foaming without the need to use harmful DBTDL. This type of additive is intended to stabilize the foam and, above all, prevent "cold flow", i.e. trapezoidal foaming. On one hand, the new substance should be safe, easy to produce, have a long shelf life and present at least the same or preferably better properties than market equivalents. The composition components disclosed below in the description and examples act on the principle of synergy and provide all these properties in the best possible way. Preferably, foams based on the crosslinking agent composition are produced in block form in continuous production, and these are preferably flexible foams, and even more preferably high-resilient or viscoelastic foams.

[0016] It has surprisingly turned out that the crosslinking agent compositions according to the invention containing sugar alcohol and urea can be used to produce foams in a smaller amount than the crosslinking agents used so far. According to the state of the art, crosslinking agents of this type available on the market should usually be dosed in an amount of at least 1.5 pph. The described invention, thanks to the selection of raw materials and their proportions, shows an analogous effect by dosing a smaller amount, e.g. not more than 1.2 pph. In the solution according to the invention, the presence of such a crosslinking agent as sugar alcohol does not adversely affect the reactivity of the foam, i.e. it does not cause a significantly longer or shorter reaction time. For a typical use of 1 .2 wt. % of the crosslinking agent in the polyurethane composition, the foam rise time will not be longer / shorter than 30 seconds.

[0017] In order to eliminate the phenomenon of "cold flow" deformation, without using the described invention, it is necessary to reduce the height of the foam block and thus less efficient production. Using the composition according to the invention, it is possible to produce higher foam blocks, wherein the difference in the dimensions of the block after seasoning measured at the top, middle and bottom (width and height) is a maximum of + / - 2%. To the best of the applicant's knowledge, there is no single composition and product made from it that would exhibit all the above-mentioned features simultaneously.

[0018] The use of the composition described below does not negatively affect the remaining parameters of the foam, which happens with other cross-linking agents and which is crucial for foam manufacturers. In addition, the cross-linking agent according to the invention is a substance safe for human health and the environment and is stable during storage.

[0019] In order to better understand the operation of the invention, the shapes of the foams without and with the composition according to the invention are presented graphically.

[0020] Figure 1 shows the cross-sectional shape of a foam block produced without using the composition according to the invention with a visible "cold flow" effect (trapezoidal shape).

[0021] Figure 2 shows the shape of the most advantageous cross-section of a foam block using the composition according to the invention (without the trapezoidal effect).

[0022] The subject of the invention in a first aspect is a crosslinking agent composition characterized in that it comprises a sugar alcohol and urea, wherein the sugar alcohol is selected from the group of alcohols containing from 3 to 15 carbon atoms, preferably maltitol and / or sorbitol and / or a mixture thereof.

[0023] Preferably, the amount of sugar alcohol in the cross-linking agent composition is 10-55 wt.%, preferably 30-55 wt.% maltitol and not more than 20 wt.% sorbitol.

[0024] Preferably, the amount of urea in the crosslinking agent composition is 8-15 wt%.

[0025] Preferably the crosslinking agent composition further comprises glycol and / or glycerin, wherein preferably the amount of glycol in the composition is not more than 25 wt.% and the amount of glycerin in the composition is not more than 20 wt.%.

[0026] Preferably, the crosslinking agent composition further comprises water, wherein preferably the amount of water in the composition is 20-50 wt%.

[0027] In a second aspect, the invention relates to the use of a crosslinking agent composition for the production of polyurethane compositions, preferably for the production of flexible polyurethane foams.

[0028] In a third aspect, the invention relates to a polyurethane composition comprising a polyurethane and comprising a crosslinking agent composition as defined above, preferably in an amount of not more than 3 wt%, more preferably not more than 2 wt%, even more preferably less than 1 .3 wt%, based on the weight of the polyurethane composition.

[0029] Preferably, the polyurethane composition comprises a crosslinking agent in an amount of not more than 1.5 wt.%, preferably not more than 1.2 wt.%, based on the weight of the polyurethane composition.

[0030] Preferably, the polyurethane composition further comprises: a polyol, an isocyanate, water, a catalyst, a surfactant, a stabilizer, wherein the polyol is a polymeric polyol of the PIPA type (a reactive polymeric polyol with a solids content of 18-22% w / w, the solids being polyurethane suspended in a polyol matrix), and / or a polymeric polyol of the SAN type (a suspension of a styrene-acrylonitrile copolymer in a polyol) and / or a polymeric polyol of the PHD type (Polyhamstoff Dispersion, a polyurea dispersion in a polyol) and / or a reactive non-polymeric polyol with a molecular weight (MW) of 400-12,000 g / mol; the isocyanate is 4,4'-diphenylmethane diisocyanate (MDI) and / or toluene diisocyanate (TDI); the catalyst is selected from amine catalysts, preferably trimethylamine, triethylamine and / or N-methylmorpholine and / or N-ethylmorpholine and / or N,N-dimethylbenzylamine and / or N,N-dimethylethanolamine and / or N,N,N',N'-tetramethyl-1 ,4-butanediamine and / or N,N-dimethylpiperazine and / or 1 ,4-diazobicyclo-2,2,2-octane and / or bis(dimethylaminoethyl)ether and / or triethylenediamine and / or dimethylalkylamines in which the alkyl group contains from 4 to 18 carbon atoms, or organometallic catalysts, preferably tin(ll) neodecanoate, tin octanoate, tin oleate, dimethyltin dilaurate and dibutyltin dilaurate; the surfactant is a silicone surfactant, preferably based on a polysiloxane-polyether copolymer; the stabilizer is diethanolamine and / or triethanolamine.

[0031] In a fourth aspect, the invention relates to a polyurethane foam obtained by reacting and foaming a polyurethane composition as defined above.

[0032] The polyurethane foam is preferably characterized in that the change in the dimensions of the width and height of the foam block after seasoning is a maximum of + / - 10%, preferably less than 5%.

[0033] The polyurethane foam is preferably produced in a continuous production process, and is preferably a flexible foam, and is even more preferably a high-resilient or viscoelastic foam.

[0034] Preferably, the polyurethane foam has the following parameters: density, determined in accordance with the PN-EN ISO 845 standard / October 2000, in the range of 20-70 kg / m3; hardness, determined in accordance with the PN-EN ISO 3386-1 standard / August 2000, in the range of 0.8-6.0 kPa; resilience, determined in accordance with the PN-EN ISO 8307 standard / October 2000, in the range of not less than 35% for high-resilience foams and not more than 20% for viscoelastic foams; tensile strength above 50 kPa, determined in accordance with the PN-EN ISO 1798 standard of March 2010; and elongation above 80%, determined in accordance with the PN-EN ISO 1798 standard of March 2010.

[0035] The ingredients are not limited to the above. It is known to a person skilled in the art what compounds can be used to obtain the above compositions and polyurethane foams, and the invention should not be limited to the following embodiments.

[0036] The crosslinking agent composition comprises at least one sugar alcohol. Sugar alcohols may include any polyhydric alcohols, including monosaccharides, disaccharides, polyols and oligosaccharides and polysaccharides. The compositions of the invention comprise at least one compound selected from the group consisting of maltitol, sorbitol, isomalt, lactitol, xylitol, threitol, erythritol and / or arabitol. Preferably, the sugar alcohol is maltitol and / or sorbitol and / or a mixture thereof in an appropriate proportion.

[0037] The nitrogen-containing compounds are selected from the group of amide compounds. Preferably, such a compound is urea.

[0038] Preferably, the crosslinking agent composition comprises at least one sugar alcohol and a nitrogen-containing compound.

[0039] As a polyol, at least one selected from the group consisting of polyether polyols and polyester polyols can be used due to the possibility of easily adjusting the nominal number of functional groups, the number average molecular weight, etc. One type of polyol alone or multiple types in combination can be used. Preferably, a PIPA type polymeric polyol and / or a SAN type polymeric polyol and / or a PHD type polymeric polyol and / or a reactive non-polymeric polyol having an average molecular weight (MW) of 400-12,000 g / mol.

[0040] Suitable isocyanates within the meaning of the invention are all polyfunctional organic isocyanates such as, for example, 4,4'-diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), hexamethylene diisocyanate and isophorone diisocyanate. The various isomers of TDI in pure form or as an isomer mixture are particularly preferred.

[0041] Examples of amine catalysts that can be used include tertiary amines such as trimethylamine, triethylamine, N-methylmorpholine, N-ethylmorpholine, N,N- dimethylbenzylamine, N,N-dimethylethanolamine, N,N,N',N'-tetramethyl-1 ,4- butanediamine, N,N-dimethylpiperazine, 1 ,4-diazobicyclo-2,2,2-octane, bis(dimethylaminoethyl)ether, triethylenediamine and dimethylalkylamines in which the alkyl group contains from 4 to 18 carbon atoms. Mixtures of these tertiary amines are frequently used. Examples of organometallic catalysts include catalysts based on bismuth, cobalt, zinc and tin. Organometallic catalysts based on tin are particularly preferred. Examples of such catalysts include tin octoate, tin oleate, dimethyltin dilaurate and dibutyltin dilaurate. As surfactants, silicone surfactants can be mentioned, which are used in foam formulations as foam stabilizers. Typical examples of silicone surfactants are polysiloxanepolyether copolymers commercially available under the trade name TEGOSTAB® (Evonik AG), NIAX™ (Momentive Performance Materials) and Dabco™ (Evonik AG).

[0042] The crosslinking agent compositions of the invention can be used, for example, with suitable solvents and diluents and / or other additives. Suitable optional solvents include all substances suitable according to the prior art. Particularly suitable are water, carboxylic esters (for example fatty acid esters) and polyesters, alcohols, glycols and polyethers. Particularly preferred are compounds with an OH group, such as water, (poly)alkylene glycols, preferably monoethylene glycol (MEG or EG), diethylene glycol (DEG), triethylene glycol (TEG), 1 ,2-propylene glycol (PG), dipropylene glycol (DPG), trimethylene glycol (propane-1 , 3-diol, PDO), tetramethylene glycol (butanediol, BDO), butyl diglycol (BDG), neopentyl glycol, 2-methylpropane-1 , 3-diol and higher homologues thereof, for example polyethylene glycol (PEG) with average molecular weights between 200 g / mol and 3000 g / mol. Particularly preferred compounds with an OH function further include polyethers having an average molecular weight of from 200 g / mol to 4500 g / mol, in particular 400 g / mol to 2000 g / mol, in particular those based on propylene oxide (PO) and / or ethylene oxide (EG).

[0043] Examples 1-29 of the crosslinking agent according to the invention

[0044] Examples of crosslinking agent implementation were carried out as follows. Water was added to a glass heating flask, then powders and liquids in the given proportion. The mixture was heated to 90°C with constant stirring for approx. 1 h.

[0045] After cooling the liquid to room temperature, each sample was left in a glass vial at room temperature for 1 month to assess whether precipitation / crystallization occurred.

[0046] The composition of the crosslinking agents is given in Table 1. The amount is given per 100 wt.% of the total weight of polyols.

[0047] Table 1

[0048] In Table 1 above, exemplary compositions containing preferred concentrations of ingredients are presented. Observations of the compositions have shown that the compositions are stable over a wide range of sugar alcohol and urea concentrations. Too high urea content causes urea to precipitate from the composition.

[0049] Examples of foam execution l-IV

[0050] The polyols and all additives except isocyanate were mixed together in a 1 -liter vessel for 30 s at a mixer speed of 3500 rpm. The isocyanate was then added and mixed for another 7 s. The whole was poured into a paper mold. The foams were conditioned for 1 h at 100°C and then for 47 h at ambient temperature (20-24°C).

[0051] Table 2 below lists foam compositions using the crosslinking agent composition according to the invention (II and IV) and, for comparison, the crosslinking agent from the prior art (I and III).

[0052] Table 2

[0053] Symbols used in Table 2: Polyol A - a PIPA type polyol with a hydroxyl number (LOH) of 43 mgKOH / g; a reactive polymeric polyol with a solids content of 18-22% wt. / wt., where the solids are polyurethane suspended in a polyol matrix.

[0054] Isocyanate - toluene diisocyanate; a mixture of isomers of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate in a ratio of 80:20.

[0055] Isocyanate index - percentage stoichiometric share of TDI in the formulation relative to other reactants, i.e. if the value is 100 then the amount of TDI and reactants is stoichiometrically equal; if the value is below 100 then there is stoichiometric undersupply of TDI; if the value is above 100 then there is excess.

[0056] Total water - water that takes part in the reaction;

[0057] B8783 - Tegostab B8783, a surfactant dedicated to HR foams;

[0058] BLV - a mixture of amines (70% solution of bis(N,N-dimethylaminoethyl)ether in dipropylene glycol and 33% solution of triethylenediamine in propylene glycol in a ratio of 1 :3);

[0059] DEOA 90% - diethanolamine, 90% solution in water;

[0060] Ortegol 204 - Evonik's crosslinking agent available on the market;

[0061] Crosslinking agent - crosslinking agent developed according to Example 28;

[0062] SO - tin octanoate, Kosmos T9.

[0063] Table 2 shows that the crosslinking agent compositions of the invention are perfectly suited to obtaining foams with the parameters desired by customers on the market, and these foams were obtained using a much lower concentration of the crosslinking agent than those known in the prior art: 1.2% instead of 1.5%, respectively, which represents a reduction in the content of this component by as much as 20% by weight.

[0064] Compositions according to tests II and IV were foamed on a technical scale on a Laader Berg low-pressure continuous foaming machine. Blocks 30 meters long and about 115 cm high were obtained. For the above tests, no trapezoidal effect (cold flow) was observed. After production, the blocks were seasoned for at least 48 h at ambient temperature.

[0065] The width and height of the produced foam blocks were measured before fresh foaming and after seasoning, i.e. after 48 h - the results are given in Table 3.

[0066] It is known that if the height of the foam changes, its width changes accordingly. The effect of the "cold flow" deformation of the height and width was calculated using the formula from document US2022204681A1 for the height: (final height / initial height)*100% and the transformed formula for the width: (final width / initial width)*100%, where in the table below the output width means the initial width and the output height means the initial height. For compositions II and IV, the effect of the deformation of the height and width was obtained, respectively:

[0067] Table 3

[0068] From the above table it is clear that the foam produced using the crosslinking agent composition according to the invention significantly reduces the effect of "cold flow" deformation. The effect obtained in the range of 98-99% is much higher than that presented in the publication US2022204681A1 , where in the best example it was 87.5%. Therefore, the use of the crosslinking agent composition according to the present invention allows for the improvement of this parameter by as much as 13%.

[0069] The parameters characterizing the foam were determined in accordance with the following standards / methods:

[0070] Hardness :

[0071] Flexible porous plastics. Determination of stress-strain characteristics in compression.

[0072] PN-EN ISO 3386-1 / August 2000

[0073] Description: A sample measuring 10 cm x 10 cm and 5 cm high is compressed by 40%, at this value the force required for compression is measured.

[0074] Resilience :

[0075] Flexible porous plastics. Determination of elasticity.

[0076] PN-EN ISO 8307 / October 2000 Description: A steel ball with a diameter of 16 mm is dropped from a height of 50 cm onto a sample measuring 10 cm x 10 cm and 5 cm high. Resilience is the percentage value of the height to which the ball returns.

[0077] SAG (Support Factor)

[0078] PN-EN ISO 3386-1 / August 2000

[0079] Description: A sample measuring 10 cm x 10 cm and 5 cm high is compressed by 65% and then by 25%. SAG is the quotient of hardness at 65% compression and hardness at 25% compression.

[0080] Density :

[0081] Porous rubbers and plastics. Determination of apparent (bulk) density.

[0082] PN-EN ISO 845 / October 2000

[0083] Description: A sample measuring 10 cm x 10 cm and 5 cm high is measured with a caliper and weighed.

[0084] Tensile strength :

[0085] ETP Determination of tensile strength and elongation

[0086] PN-EN ISO 1798 March 2010

[0087] Description: A 15 cm long sample with a cross section of 1.3 cm x 1.25 cm (+ / - 0.25 cm) is stretched between clamps spaced 10 cm apart until it breaks. The result is the force required to break the sample.

[0088] Elongation :

[0089] ETP Determination of tensile strength and elongation.

[0090] PN-EN ISO 1798 March 2010

[0091] Description: A 15 cm long sample with a cross section of 1.3 cm x 1.25 cm (+ / - 0.25 cm) is stretched between clamps spaced 10 cm apart until it breaks. The result is the percentage of the clamp spacing between the initial position and the moment of sample breakage.

[0092] Recovery time :

[0093] A 10x10x10 cm foam is compressed by a testing machine plate by 75% along the direction of growth, after 1 minute the force is released and the time required for it to recover to its original shape is measured (using a stopwatch).

[0094] Molecular weight and OH value : Number-average molecular weights are determined by gel permeation chromatography (GPC), especially using polypropylene glycol as reference substance and tetrahydrofuran (THF) as eluent. In particular, OH values can be determined according to DIN DIN 53240- 2:2007-11.

Claims

AMENDED CLAIMS received by the International Bureau on May 20, 2025 (20.05.2025)Claims1. A crosslinking agent composition characterized in that it comprises:- a sugar alcohol selected from maltitol and / or sorbitol and / or a mixture thereof, wherein the amount of sugar alcohol in the composition is 30-55 wt.%,- urea in the amount of 8-15 wt.%. of the composition,- glycol in the amount of 3-25 wt.%. or glycerin in the amount of 10-20 wt.%. of the composition- water in the amount of 25-50 wt.%. of the composition.

2. Use of a crosslinking agent composition as defined in claim 1 for the production of polyurethane compositions, preferably for the production of flexible polyurethane foams.

3. A polyurethane composition comprising a polyurethane characterized in that it comprises a crosslinking agent composition according to claim 1 , preferably in an amount of not more than 3 wt.%, more preferably not more than 2 wt.%, even more preferably less than 1.3 wt.%, based on the weight of the polyurethane composition.

4. The polyurethane composition according to claim 3, characterized in that it comprises a crosslinking agent composition according to claim 1 in an amount of not more than 1.5 wt.%, preferably not more than 1.2 wt.%, based on the weight of the polyurethane composition.

5. The polyurethane composition according to claim 3 or 4, characterized in that it further comprises: 100 parts by weight of a polyol, and 35-40 parts by weight of an isocyanate, 2-3 parts by weight of water, 0.1-1 parts by weight of a catalyst, 0.1-1 parts by weight of a surfactant, 0.5-1 parts by weight of a stabilizer, wherein the polyol is a polymeric polyol of the PIPA type (a reactive polymeric polyol with a solids content of 18-22% w / w, the solids being polyurethane suspended in a polyol matrix), and / or a polymeric polyol of the SAN type (a suspension of a styreneacrylonitrile copolymer in a polyol) and / or a polymeric polyol of the PHD type (Polyhamstoff Dispersion, polyurea dispersion in polyol) and / or a reactive non- polymeric polyol with a molecular weight (MW) of 400-12,000 g / mol; the isocyanate is 4,4'-diphenylmethane diisocyanate (MDI) and / or toluene diisocyanate (TDI); the catalyst is selected from amine catalysts, preferably trimethylamine, triethylamine and / or N-methylmorpholine and / or N-ethylmorpholine and / or N,N-dimethylbenzylamine and / or N,N-dimethylethanolamine and / or N,N,N',N'-tetramethyl-1 ,4-butanediamine and / or N,N-dimethylpiperazine and / or 1 ,4-diazobicyclo-2,2,2-octane and / or bis(dimethylaminoethyl)ether and / or triethylenediamine and / or dimethylalkylamines inwhich the alkyl group contains from 4 to 18 carbon atoms, or organometallic catalysts, preferably tin(ll) neodecanoate, tin octanoate, tin oleate, dimethyltin dilaurate and dibutyltin dilaurate; the surfactant is a silicone surfactant, preferably based on a polysiloxane-polyether copolymer; the stabilizer is diethanolamine and / or triethanolamine.

6. A polyurethane foam, characterized in that it is obtained by reacting and foaming the polyurethane composition as defined in any one of claims 3-5.

7. The polyurethane foam according to claim 6, characterized in that the change in the dimensions of the width and height of the foam block after seasoning is a maximum of + / - 10%, preferably less than 5%.

8. The polyurethane foam according to claim 6 or 7, characterized in that it is produced in continuous production, and is preferably a flexible foam, and more preferably a high- resilient or viscoelastic foam.

9. The polyurethane foam according to any one of claims 6-8, characterized in that it has the following parameters: density, determined in accordance with the PN-EN ISO 845 standard / October 2000, in the range of 20-70 kg / m3; hardness, determined in accordance with the PN-EN ISO 3386-1 standard / August 2000, in the range of 0.8-6.0 kPa; resilience, determined in accordance with the PN-EN ISO 8307 standard / October 2000, in the range of not less than 35% for high-resilience foams and not more than 20% for viscoelastic foams; tensile strength above 50 kPa, determined in accordance with the PN-EN ISO 1798 standard March 2010; and elongation above 80%, determined in accordance with the standard PN-EN ISO 1798 March 2010.

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