Polylysine-based in situ foams.

Abstract

The present invention relates to a system for producing an in situ foam, comprising one or more poly(amino acids) (A), one or more components (B) capable of reacting with said poly(amino acids) (A), and one or more amphoteric polymers (C), wherein component (B) is selected from a reducing sugar, 1,3-dihydroxyacetone, glycolaldehyde, glyceraldehyde, or any mixture thereof, and a method for producing the in situ foam.

Description

[Technical Field]

[0001] The present invention relates to a system for producing an in situ foam, comprising one or more poly(amino acids) (A), one or more components (B) capable of reacting with said poly(amino acids) (A), and one or more amphoteric polymers (C), wherein component (B) is selected from a reducing sugar, 1,3-dihydroxyacetone, glycolaldehyde, glyceraldehyde, or any mixture thereof, and a method for producing the in situ foam. [Background technology]

[0002] Reactive non-thermoplastic (thermosetting) polymer foams are used in many applications, such as thermal insulation, sound absorption, cushioning, cleaning materials, and packaging. In most cases, these reactive non-thermoplastic foams are produced by using a suitable blowing agent, such as hexane, pentane, butane, or its isomers, or fluorocarbon hydrates. If the polymer reaction is not sufficiently exothermic, the foam must be exposed to heat to allow the blowing agent to evaporate. This is achieved by using a hot mold, hot air, or microwave technology. In most cases, a large amount of heat must be applied to provide insulation during foam expansion. Furthermore, high safety efforts must be ensured for the safe transportation, storage, handling, and disposal of flammable blowing agents. One example is European Patent Application Publication No. 0031513, which describes the preparation of elastic open-cell foams based on urea-formaldehyde using the blowing agent pentane.

[0003] Another possibility is to use gases such as CO2 to enable the foaming of reactive non-thermoplastic polymer foams. In this case, a high pressure drop is required to allow the foam to form. This can only be achieved with cost-intensive pressure-resistant equipment in foam production.

[0004] Flexible polyurethane foams can be blown using water. Water reacts with the isocyanate groups of the respective isocyanates (e.g., TDI or MDI) to produce disubstituted urea and CO₂, which acts as the intrinsic blowing agent in foam formation. The final foam exhibits high flexibility and excellent sound absorption. However, the use of isocyanates requires high safety efforts for safe transportation, storage, handling, and disposal.

[0005] To overcome the above drawbacks, open-cell water-based air-blown foams can be used.

[0006] An example of an air-blown foam is described in WO 2017 / 067792. A mixture of more than 50% inorganic filler, cationic or amphoteric polymer, crosslinker, surfactant, and other additives is mixed with air and cured to produce a foam with a density of 10-50 kg / m. 3 air-blown foams are produced. The resulting foams exhibit good thermal insulation values ​​(approximately 35 mW / m*K) and low heat values ​​of less than 3.0 MJ / kg. The most important application of these foams is the insulation of building cavities. On the other hand, these rigid foams are very brittle and exhibit some degree of shrinkage (>5%) (freestanding foams - no mold).

[0007] Another example is a foam based on urea-formaldehyde condensates, as described in U.S. Patent No. 2,789,095. A mixture of urea-formaldehyde condensates with suitable curing agents, surfactants, and other additives is mixed with air and cured to produce a foam with a viscosity of 12-15 kg / m. 3 This produces air-blown foams with a density of approximately 35 mW / m*K. The resulting foams exhibit good thermal insulation values ​​(approximately 35 mW / m*K) and good flame retardancy (structural class B2 (DIN 4102)). On the other hand, these rigid foams can be brittle and emit large amounts of formaldehyde.

[0008] WO 2016 / 009062 and WO 2011 / 138458 disclose binders useful for consolidating loosely assembled materials such as fibers, comprising the reaction product of a carbohydrate reactant and a polyamine. Foams using the binders are not disclosed.

[0009] WO 2022 / 136613 discloses a binder composition comprising, as component A, polylysine having a total weight-average molecular weight Mw of at least 800 g / mol and, as component B, 1,3-dihydroxyacetone, glycolaldehyde, glyceraldehyde, or a mixture thereof, and its use for producing a lignocellulosic composite product. Foams using the binder are not disclosed.

[0010] WO 2022 / 136614 relates to a binder composition containing a polyamine and hydroxyacetone for composite articles. Foams using the binder composition are not disclosed.

[0011] U.S. Patent Application Publication No. 2011 / 0257284 describes a method for making flame-retardant polyurethane foams using hyperbranched nitrogen-containing polymers, particularly hyperbranched polylysine, hyperbranched polyisocyanurate, and hyperbranched polyesteramide, to impart flame retardancy to the polyurethane foam. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] European Patent Application Publication No. 0031513 [Patent Document 2] International Publication No. 2017 / 067792 [Patent Document 3] U.S. Patent No. 2,789,095 [Patent Document 4] International Publication No. 2022 / 136613 [Patent Document 5] International Publication No. 2022 / 136614 [Patent Document 6] US Patent Application Publication No. 2011 / 0257284 Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention has been made in view of the above-mentioned prior art, and an object of the present invention is to provide an open-cell, formaldehyde- and isocyanate-free flexible foam having good sound absorption properties, which can be obtained from bio-based and aqueous raw materials and can be processed on-site as an air-blown foam. [Means for solving the problem]

[0014] This object is solved by a foam and a system for producing an in situ foam, comprising one or more poly(amino acids) (A), one or more components (B) capable of reacting with said poly(amino acids) (A), and one or more amphoteric polymers (C), wherein component (B) is selected from reducing sugars, 1,3-dihydroxyacetone, glycolaldehyde, glyceraldehyde, or any mixture thereof.

[0015] Preferably, the foam is not a polyurethane foam. Preferably, the foaming mixture does not contain isocyanates and / or polyols. Preferably, the foaming mixture comprises more than 50 wt. %, more preferably more than 70 wt. %, of poly(amino acid) (A), based on the total solids content of reactive components (A) and (B).

[0016] Preferably, the method comprises: 1 to 40% by weight of one or more poly(amino acids) (A) 1 to 15% by weight of one or more components (B) capable of reacting with the poly(amino acid) (A). 1 to 10% by weight of one or more amphoteric polymers (C), 1 to 15 wt. % of one or more surfactants (D); 1 to 90% by weight of water (E), 0 to 90 wt. % of one or more additional additives (F) Including, The method includes a step of foaming the mixture, wherein the total weight percentage of the components (A) to (F) is 100% by weight.

[0017] More preferably, the method comprises: 10 to 20% by weight of one or more poly(amino acids) (A) 2 to 8% by weight of one or more components (B) capable of reacting with the poly(amino acid) (A). 1 to 3 wt. % of one or more amphoteric polymers (C), 3 to 12 wt. % of one or more surfactants (D); 50 to 80% by weight of water (E), 0 to 34 wt. % of one or more additional additives (F) Including, The method includes a step of foaming the mixture, wherein the total weight percentages of components A) to F) is 100% by weight.

[0018] More preferably, the method comprises foaming a mixture consisting essentially of components (A)-(E) in the amounts described above.

[0019] Most preferably, the method comprises: 10 to 20% by weight of one or more poly(amino acids) (A) 2 to 8% by weight of one or more components (B) capable of reacting with the poly(amino acid) (A). 1 to 3 wt. % of one or more amphoteric polymers (C), 3 to 12 wt. % of one or more surfactants (D); 57-80% by weight of water (E) Including, and foaming the mixture, the total weight percentages of components A) to E) being 100% by weight. DETAILED DESCRIPTION OF THE INVENTION

[0020] Component (A) As component (A), poly(amino acids), such as synthetic poly(amino acids), natural poly(amino acids), polypeptides, proteins, or mixtures thereof, are used. Poly(amino acids) are produced by polymerization of amino acids. Poly(amino acids) can be obtained by chemical synthesis or biosynthesis in living organisms. In particular, proteins can be obtained by biosynthesis in living organisms. Polypeptides can be obtained by protein hydrolysis.

[0021] According to the present invention, the term poly(amino acid) may also include poly(amino acid) derivatives which may be obtained by modification of the poly(amino acid) after polymer synthesis.

[0022] Preferred amino acids used in the polymerization reaction are diamino acids containing two amine (-NH) groups and at least one carboxyl (-COOH) functional group. Such diamino acids can be ornithine, diaminopimelic acid, 2,3-diaminopropionic acid, 2,4-diaminobutyric acid, and / or lysine, preferably lysine, more preferably L-lysine. Although they are sometimes called diamino acids, according to the present invention, asparagine and glutamine are not included in the group of diamino acids because the second functional group is an amide (CO-NH) and not an amine (-NH).

[0023] Preferably, polylysine is used as poly(amino acid).Polylysine can be produced by polymerization of lysine.Lysine itself is produced by fermenting corn starch in the presence of suitable bacteria.The production of polylysine is generally known, and can be carried out, for example, as described in WO2016 / 062578 or from lysine salts described in WO2007 / 060119.A preferred method for producing polylysine is described in WO2022 / 136613.

[0024] Preferably, component (A) comprises at least one polylysine or consists of one or more polylysines, which polylysines are monomeric lysines, preferably L-lysine, and optionally: a) an amino acid (preferably containing at least two amino groups); b) an amine containing at least two amino groups (wherein the amine is not an amino acid); and c) dicarboxylic and / or tricarboxylic acids (preferably not amino acids); and the polymerization product of another monomer selected from the group consisting of: Here, at least 50% by weight, preferably at least 75% by weight, most preferably 100% by weight of lysine, based on the total amount of monomers, is used as a monomer for the polymerization reaction.

[0025] Preferably, the poly(amino acid) (A) has a weight-average molecular weight Mw in the range of 800 to 20,000 g / mol, more preferably in the range of 1,500 to 8,000 g / mol. The weight-average molecular weight is determined by size-exclusion chromatography (SEC) of the hydroxylated polymethacrylate using 0.1% (w / w) trifluoroacetate as the solvent and 0.1 M NaCl in distilled water as the eluent, calibrated with poly(2-vinylpyridine) standards. Most preferably, polylysine in an aqueous formulation having a molecular weight of 800 to 8,000 g / mol is used as component (A).

[0026] Ingredient (B) The foaming mixture contains one or more components (B) capable of reacting with the poly(amino acid) (A), selected from reducing sugars, 1,3-dihydroxyacetone, glycolaldehyde, glyceraldehyde, or any mixture thereof. Preferably, hydroxyacetone or 1,3-dihydroxyacetone is used as component (B).

[0027] Preferably, the weight ratio of poly(amino acid) (A) to component (B) is in the range of 2:1 to 5:1.

[0028] Poly(amino acids) and reducing sugars derived from natural sources can be used as raw materials to produce essentially bio-based foams.

[0029] Assume that components A and B undergo a Maillard reaction. The first step is the addition of a free amine group of a (poly)amino acid (component (A)) to a carbonyl group of a reducing sugar (ketose / aldose) (component (B)). The glycosylamine formed is unstable and loses one water molecule, undergoing a Heyns / Amadori rearrangement to form a Heyns / Amadori compound (aldosamine / ketosamine).

[0030] In the case of the reaction of polylysine with (di)hydroxyacetone, a crosslinked, thermosetting, brown solid material is formed.

[0031] Ingredients (C) Suitable amphoteric polymers for component (C) are described, for example, in WO 2004 / 087818 and WO 2005 / 012637. Preferred are copolymers containing units derived from vinylamine and vinylformamide or vinylamine and unsaturated carboxylic acid / carboxylate, and terpolymers containing units derived from vinylamine, vinylformamide, and unsaturated carboxylic acid / carboxylate. Particularly preferred are copolymers formed from vinylamine and sodium acrylate, and terpolymers formed from vinylamine, vinylformamide, and sodium acrylate. XELOREX® F 3000 is an example.

[0032] Ingredients (D) Component (D) of the system comprises one or more surfactants used in foam formation and stabilization. Anionic, cationic, nonionic or amphoteric surfactants can be used.

[0033] Suitable anionic surfactants are diphenylene oxide sulfonates, alkane- and alkylbenzenesulfonates, alkylnaphthalenesulfonates, olefinsulfonates, alkyl ether sulfonates, alkyl sulfates, alkyl ether sulfates, α-sulfofatty acid esters, acylaminoalkanesulfonates, acyl isethionates, alkyl ether carboxylates, N-acylsarcosinates, alkyl and alkyl ether phosphates.

[0034] Useful nonionic surfactants include alkylphenol polyglycol ethers, fatty alcohol polyglycol ethers, fatty acid polyglycol ethers, fatty acid alkanolamides, EO-PO block copolymers, amine oxides, glyceryl fatty acid esters, sorbitan esters, and alkyl polyglucosides. Useful cationic surfactants include alkyltriammonium salts, alkylbenzyldimethylammonium salts, and alkylpyridinium salts.

[0035] Mixtures of anionic and nonionic surfactants are particularly preferably used.

[0036] Preferably, a mixture of an anionic surfactant and a nonionic surfactant is used as surfactant (D), and more preferably, a sodium salt of a (C12-C14) fatty alcohol ether sulfate, a (C12-C14)-alkyl polyglycoside, or a mixture thereof is used as surfactant (D).

[0037] Preferably, the weight ratio of the anionic surfactant to the nonionic surfactant is in the range of 50:50 to 90:10.

[0038] Ingredient (E) Water is used as component (E). Preferably, components (A), (B), (C), and (D) are used as an aqueous solution or dispersion. Additional water may be added to achieve the above composition of the mixture and adjust the viscosity.

[0039] Ingredient (F) Flame retardants, fillers and salts, such as sodium formate, sodium acetate, sodium citrate, sodium chloride, can be used as further components (F). Preferably, flame retardants are used as additives (F).

[0040] The subject of the invention is also a process for producing in situ foams by preparing aqueous solutions or dispersions of components (A) to (F) of the system described above and foaming the aqueous solutions or dispersions with a gas or gas mixture.

[0041] In situ foams can be obtained by mixing an aqueous composition containing components (A) to (F) with a gas or gas mixture under (super)atmospheric pressure to foam the composition and applying mechanical forces, such as stirring or shearing with a static mixer. It is also possible to foam the aqueous composition by dispersing an inert gas in the form of fine bubbles. The introduction of bubbles into the aqueous composition can be achieved by beating, shaking, stirring, whipping, or using a rotor device. Mixers with stator and / or rotor elements are preferably used.

[0042] The gas or gas mixture used preferably comprises an inert gas, such as nitrogen, argon, carbon dioxide or oxygen, etc. Air is particularly preferably used.

[0043] The preferred method is (a) preparing an aqueous solution or suspension containing components (A) to (F); (b) foaming the aqueous solution or suspension by introducing a gas or gas mixture into said aqueous solution or suspension through one or more mixing elements; (c) transferring the foam obtained in step (b) into a mold; and (d) curing and drying the foam at 50-160°C Includes:

[0044] The subject of the present invention is also a foam obtainable by the above process, the dried foam preferably comprising more than 50% by weight, more preferably more than 65% by weight, of components (A) and (B) incorporated as a reticulated matrix of the foam.

[0045] Preferably, the foam has a compressibility of 10 to 60 kg / m, determined according to DIN 53420. 3 The density can be adjusted by the amount of amphoteric polymer (component (C)) and surfactant (component (D)). The density can be increased by using more reactive components (A) and (B) in the system to produce the in-situ foam.

[0046] Preferably, the foam has a Shore hardness 000, determined according to ASTM D 2240, in the range of 20-80.

[0047] The resulting air-blown foam exhibits high flexibility (Shore hardness) and good sound absorption properties.

[0048] The foam according to the present invention comprises -Can be obtained by air blow foaming process. - Formaldehyde and isocyanate free. -Open-cell type, with an open-cell content of over 95% as measured by optical microscope. -It is water-based. - It is not brittle and exhibits high flexibility as evidenced by low Shore hardness values. -Good sound absorption over a wide frequency range and low airflow resistance.

[0049] Example The present invention will be described in more detail and specifically below with reference to examples, but the present invention is not limited to these examples.

[0050] Raw materials used: Surfactant 1: anionic surfactant Disponil® FES 32 (31% by weight in water, fatty alcohol (C12-C14) ether (approximately 4 EO) sulfate sodium salt, BASF SE); Surfactant 2: nonionic surfactant Glucopon® GD 70 (68% by weight in water, C10-C12-alkyl polyglucoside); Water: deionized water; Polylysine-1: weight average molecular weight Mw about 2,000 g / mol (50% by weight in water). Polylysine-5: weight average molecular weight Mw about 5,500 g / mol (50% by weight in water); Polylysine-1 and polylysine-5 were prepared by heat treating L-lysine according to Example 1 of WO 2022 / 136613.

[0051] Amphoteric polyvinylamine Xelorex® F3000 (11 wt% NVF / VA / AA copolymer (35 / 35 / 30 mol%) in water), Solenis-BASF; Crosslinker: 1,3-dihydroxyacetone (70 wt % in water, Sigma-Aldrich).

[0052] Weight average molecular weight M of polylysine w Decision M w under the following conditions: Solvent and eluent: 0.1% (w / w) trifluoroacetate, 0.1 M NaCl in distilled water ·Flow rate: 0.8 ml / min ·Injection volume: 100μl Filter the sample through a Sartorius Minisart RC25 (0.2 μm) filter. Column material: Hydroxylated polymethacrylate (TSKgel G3000PWXL) Column size: 7.8 mm inner diameter, 30 cm length Column temperature: 35℃ Detector: DRI Agilent 1100 UV GAT-LCD503 [232 nm] Calibration using poly(2-vinylpyridine) standards (PSS, Mainz, Germany) in the molar mass range of 620–2,890,000 g / mol and pyridine (79 g / mol) The maximum cumulative volume was set to 29.01 mL. M w The calculation of lysine includes lysine oligomers and polymers as well as monomeric lysine. was determined by size exclusion chromatography.

[0053] Foam characterization The foam density was determined according to DIN 53420.

[0054] Shore hardness was measured according to ASTM D 2240. A scale of 000 was used for measurements on low density foams (sphere diameter 2.4 mm, spring force 1.111 N).

[0055] The acoustic absorption was determined by impedance tube measurements according to ISO 10534-2, the sample thickness was 30 mm and the diameter was 100 mm.

[0056] The compressive stress values ​​(compressive load deflection) CV 40 were determined in accordance with DIN EN ISO 3386-1.

[0057] Examples 1-12: Preparation of air-blown polylysine-based foams To the mixture of surfactant 1 and surfactant 2 in water, an aqueous dispersion of polylysine and finally an aqueous dispersion of amphoteric polyvinylamine were added and mixed by gentle hand shaking for a few seconds. Next, the cross-linker in water was added, and the entire mixture was processed at high speed using a high-shear mixer (Krups Handmixer 3Mix7000) for 1 minute. This produced a fine-celled, air-blown foam with an open cell content of >95% as measured by optical microscopy, which was then poured into a suitable mold (e.g., a 10 x 10 x 5 cm box). The liquid foam was allowed to cure and dried at 100°C for 24 hours. After cooling, the now solid foam was demolded.

[0058] The composition (parts by weight) and Shore hardness 000 (at 23°C and 50% relative humidity) of the obtained foams are shown in Table 1. The foam densities of the samples of Examples 1 to 9 after conditioning at 50% relative humidity for 24 hours were 24 to 28 kg / m 3 It was determined that the range was

[0059] The resulting foam has an open-cell structure (more than 95% open cells as measured by optical microscopy) and, like common open-cell PUR flexible foams, exhibits good sound absorption in the frequency range of 100 to 5,000 Hz, with a maximum sound absorption around 2,000 Hz. The sound absorption coefficient of the foam obtained in Example 1 is shown in Table 2.

[0060] The mechanical properties after temperature and humidity conditioning at 23°C and 50% relative humidity are shown in Table 3. The higher the tempering temperature, the higher the Shore hardness and compressive load of the foam. The higher the relative humidity conditioning, the softer the foam.

[0061] In the absence of a crosslinker (Example 11), the presence of low molecular weight polylysine (Example 12), or the absence of a stabilizing prepolymer polyvinylamine (Example 10), less homogeneous foams may be achieved after curing.

[0062] [Table 1]

[0063] [Table 2]

[0064] [Table 3]

[0065] Comparative Example C1: To a mixture of surfactant 1, Disponil® FES 32 (2.4 g, 31%), and surfactant 2, Glucopon® GD 70 (0.5 g, 68%) in water (22.1 g), the crosslinker glyoxal in water (1 g, 2%) was added and mixed by gentle shaking for a few seconds. The mixture was processed at high speed using a high-shear mixer for 1 minute. This produced a fine-celled, air-blown foam. An aqueous dispersion of amphoteric polyvinylamine Xelorex® F3000 (25 g, 11%) was carefully added to the foam and quickly homogenized. The mixture was poured into a 10 x 10 x 5 cm box mold. The liquid foam was cured and dried at 50°C for 24 hours. 32 kg / m 3 After cooling, the now solid foam was removed from the mold.

[0066] The free-standing flexible foam of Example C1 demolded collapsed at 23°C / 50% relative humidity, with volumetric shrinkage of 0% after 30 minutes, 10% after 120 minutes, 18% after 210 minutes, 24% after 330 minutes, and 47% after 3 days. The free-standing flexible foam of Example 1 demolded was stable under these conditions and showed no dimensional change.

[0067] Comparative Example C2: Air-blown foam made from urea-formaldehyde resin Component A was prepared by mixing 25 g of water-soluble urea-formaldehyde precondensate (Basopor® 293 powder) with 41 g of water by stirring. Once dissolved, 3 g of urea was added and stirred for at least 1 hour. After allowing to stand for 12 hours, 15 g of water was added. Component B was prepared by mixing 4.7 mL of a blowing agent (Basomol® 514 liquid) (aqueous solution containing 25% H3PO4 (85%), 4% resorcinol, and 20% sodium dibenzoate; pH 1-2) with 100 mL of water and stirring for 30 minutes. Using a high-shear mixer, 25 g of Component B was mixed at high speed for 1 minute. This produced a fine-cell, air-blown foam. 47 g of Component A was carefully added to the foam and quickly homogenized. The mixture was poured into a 10 x 10 x 5 cm box mold. The liquid foam was allowed to cure and then dried at 50°C for 24 hours. 18.5 kg / m 3 After cooling, the now solid foam was removed from the mold.

[0068] Note: The final density of air-blown foams cannot be adjusted over a wide range like solvent-blown foams. Foam density is determined by the specific blowing agent and foaming technique settings. In the examples and comparative examples shown, the same foaming technique using a high-shear mixer is applied, so the densities of the resulting foams made from polylysine / dihydroxyacetone, polyvinylamine / glyoxal, and urea / formaldehyde may vary due to different chemistries, solids contents, viscosities, and optimized blowing agents.

[0069] [Table 4]

[0070] This indicates that polylysine / dihydroxyacetone is a flexible, non-brittle foam, whereas other air-blown foams based on urea-formaldehyde resins are not flexible.

Claims

1. A system for producing in situ foams, comprising one or more poly(amino acids) (A), one or more components (B) capable of reacting with said poly(amino acids) (A), and one or more amphoteric polymers (C), wherein component (B) is selected from a reducing sugar, 1,3-dihydroxyacetone, glycolaldehyde, glyceraldehyde, or any mixture thereof.

2. 1 to 40% by weight of one or more poly(amino acids) (A); 1 to 15% by weight of one or more components (B) capable of reacting with the poly(amino acid) (A). 1 to 10% by weight of one or more amphoteric polymers (C), 1 to 15 wt. % of one or more surfactants (D), 1 to 90% by weight of water (E), 0-90% by weight of one or more additional additives (F) Including, 2. The system of claim 1, wherein the sum of the weight percentages of components (A) through (F) is 100% by weight.

3. 3. The system according to claim 1 or 2, wherein the poly(amino acid) (A) is polylysine having a weight average molecular weight Mw in the range of 800 to 20,000 g / mol as measured by size exclusion chromatography (SEC).

4. 4. A system according to claim 1, wherein 1,3-dihydroxyacetone is used as component (B).

5. 5. The system according to claim 1, wherein a terpolymer comprising vinylamine, vinylformamide and sodium acrylate units is used as amphoteric polymer (C).

6. 6. The system according to claim 1, wherein a sodium salt of a (C12-14)-fatty alcohol ether sulfate, a (C12-14)-alkyl polyglycoside or a mixture thereof is used as surfactant (D).

7. 7. The system according to claim 1, wherein a flame retardant is used as additive (F).

8. 8. The system according to claim 1, wherein the weight ratio of poly(amino acid) (A) to component (B) is in the range of 2.5:1 to 5:

1.

9. 9. A system according to any one of claims 1 to 8, wherein a mixture of anionic and nonionic surfactants is used in a weight ratio of anionic surfactant to nonionic surfactant ranging from 50:50 to 90:

10.

10. 10. A method for producing an in situ foam by preparing an aqueous solution or dispersion of components (A) to (F) of the system according to any one of claims 1 to 9 and foaming said aqueous solution or dispersion with a gas or gas mixture.

11. (a) preparing an aqueous solution or suspension containing components (A) to (F); (b) foaming the aqueous solution or suspension by introducing a gas or gas mixture into said aqueous solution or suspension through one or more mixing elements; (c) transferring the foam obtained in step (b) into a mold; and (d) curing and drying the foam at 50-160°C 11. The method of claim 10, comprising:

12. 12. An in situ foam obtainable by the method of claim 10 or 11.

13. 10 to 60 kg / m, determined according to DIN 53420 3 13. The in situ foam of claim 12 having a density in the range of

14. 14. The foam in place of claim 12 or 13, having a Shore hardness, determined according to ASTM D 2240, in the range of 20 to 80.

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