The present invention relates to a system for producing an in situ foam and a method for producing the same, the system comprising one or more poly (amino acids) (a), one or more components (B) capable of reacting with the 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.
Reactive non-thermoplastic (thermoset) polymer foams are used in many applications, such as thermal insulation, sound absorption, cushioning, cleaning, packaging, and many others. In most cases, these reactive non-thermoplastic foams are produced by using a suitable blowing agent (e.g., hexane, pentane, butane or isomers thereof or fluorocarbon hydrates or others). For the polymer reaction to be exothermic enough, the foam must be exposed to heat to enable the blowing agent to evaporate. This is achieved by hot molds, hot air or using microwave technology. In most cases, a large amount of heat must be applied due to the insulating effect during expansion of the foam. In addition, high safety inputs must be ensured for the safe transport, storage, processing and disposal of the combustible foaming agents. An example is EP 0 031 513 A2, which describes the preparation of an elastic open-cell foam based on urea-formaldehyde with the blowing agent pentane.
Another possibility is to use a gas (e.g. CO2) to enable foaming of the reactive non-thermoplastic polymer foam. In this case, a high pressure drop is necessary to be able to form a foam. This can only be achieved by means of cost-intensive pressure-resistant equipment in the production of foam.
The flexible polyurethane foam may be foamed by using water. Water reacts with isocyanate groups of the corresponding isocyanate (e.g., TDI or MDI) to form disubstituted urea and CO2.CO2 act as inherent blowing agents in foam formation. The final foam shows high flexibility and good sound absorption. However, the use of isocyanates leads to high safety inputs in terms of safe transport, storage, processing and handling.
To overcome the mentioned disadvantages, open-cell, water-based, air-blown foams may be used.
An example of an air blown foam is described in WO 2017/067792. A mixture of >50% inorganic filler, cationic or amphoteric polymer, cross-linking agent, surfactant and other additives is mixed with air and cured to produce an air blown foam having a density of 10 to 50kg/m3. The resulting foam showed good heat insulation values (about 35 mW/mK) and a low heating value of less than 3.0 mJ/kg. The most important application of these foams is the insulation of cavities in buildings. On the other hand, these rigid foams are highly brittle and exhibit some degree of shrinkage (> 5%) (free-standing foam-no mold).
Another example is a foam based on urea-formaldehyde condensate as described in US 2789095. The urea-formaldehyde condensate is mixed with a mixture of suitable curing agents, surfactants and other additives and cured with air to produce an air blown foam having a density of 12 to 15kg/m3. The resulting foam shows good heat insulation values (about 35mW/m x K) and good flame retardant properties [ construction grade B2 (DIN 4102) ]. On the other hand, these rigid foams are brittle and may show significant formaldehyde emissions.
WO 2016/009062 and WO 2011/138458 disclose a binder comprising the reaction product of a carbohydrate reactant and a polyamine, useful for consolidating loosely assembled matter such as fibers. Foams using this binder are not disclosed.
WO 2022/136613 discloses a binder composition comprising polylysine having a total weight average molecular weight Mw of at least 800g/mol as component a and 1, 3-dihydroxyacetone, glycolaldehyde, glyceraldehyde or a mixture thereof as component B and the use for manufacturing lignocellulosic composite articles. Foams using this binder are not disclosed.
WO 2022/136614 relates to a binder composition for composite articles comprising a polyamine and hydroxyacetone. Foams using the adhesive composition are not disclosed.
US2011/0257284 A1 describes a process for producing flame retardant polyurethane foams using hyperbranched nitrogen-containing polymers (in particular hyperbranched polylysines, hyperbranched polyisocyanurates and hyperbranched polyesteramides) for providing flame retardancy to polyurethane foams.
Disclosure of Invention
The present invention has been made in view of the above prior art and it is an object of the present invention to provide an open-celled, formaldehyde and isocyanate free flexible foam with good sound absorption which can be obtained from bio-based and water-based materials and processed in situ as an air blown foam.
Problems to be solved
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.
Preferably, the foam is not a polyurethane foam. Preferably, the foaming mixture is free of isocyanate and/or polyol. Preferably, the foaming mixture comprises more than 50wt. -%, more preferably more than 70wt. -% of poly (amino acid) (a) based on the solids of the sum of reactive components (a) and (B).
Preferably, the method comprises foaming a mixture comprising
1 To 40wt. -% of one or more poly (amino acids) (a)
1 To 15wt. -% of one or more components (B) capable of reacting with the poly (amino acid) (a)
1 To 10wt. -% of one or more amphoteric polymers (C),
1 To 15wt. -% of one or more surfactants (D),
1 To 90wt. -% of water (E),
0 To 90wt. -% of one or more additional additives (F),
Wherein the sum of the percentages by weight of components (A) to (F) is 100wt. -%.
More preferably, the method comprises foaming a mixture comprising
10 To 20wt. -% of one or more poly (amino acids) (a)
2 To 8wt. -% of one or more components (B) capable of reacting with the poly (amino acid) (a)
1 To 3wt. -% of one or more amphoteric polymers (C),
3 To 12wt. -% of one or more surfactants (D),
50 To 80wt. -% of water (E),
0 To 34wt. -% of one or more additional additives (F),
Wherein the sum of the percentages by weight of components A) to F) is 100wt. -%.
More preferably, the method comprises foaming a mixture consisting essentially of the above amounts of components (a) to (E).
Most preferably, the method comprises foaming a mixture consisting of
10 To 20wt. -% of one or more poly (amino acids) (a)
2 To 8wt. -% of one or more components (B) capable of reacting with the poly (amino acid) (a)
1 To 3wt. -% of one or more amphoteric polymers (C),
3 To 12wt. -% of one or more surfactants (D),
57 To 80wt. -% of water (E),
Wherein the sum of the percentages by weight of components A) to E) is 100wt. -%.
Component (A)
As component (a) poly (amino acids) (e.g., 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 by biosynthesis in living organisms. In particular, proteins can be obtained by biosynthesis in living organisms. The polypeptide may be obtained by hydrolysis of a protein.
According to the present invention, the term poly (amino acid) may also include poly (amino acid) derivatives that may be obtained by modifying poly (amino acid) after polymer synthesis.
Preferred amino acids for polymerization are diamino acids comprising two amine groups (-NH2) and at least one carboxyl (-COOH) functional group. Such diamino acids may 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 named diamino acids, asparagine and glutamine are not included in the group of diamino acids according to the present invention because the second functional group is an amide (CO-NH2) rather than an amine (-NH2).
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 as described, for example, in WO 2016062578 or from lysine salts as described in WO 2007060119. A preferred process for producing polylysine is described in WO 2022/136613.
Preferably component (A) comprises or consists of at least one polylysine, which is the polymerization product of monomeric lysine, preferably L-lysine and optionally further monomers selected from the group consisting of
A) Amino acids, preferably comprising at least two amino groups,
B) Amines containing at least two amino groups, wherein the amines are not amino acids, and
C) Di-and/or tri-carboxylic acids, which are preferably not amino acids,
Wherein at least 50wt. -%, preferably at least 75wt. -%, most preferably 100wt. -% of lysine, based on the total amount of monomers, are used as monomers for the polymerization reaction.
Preferably the poly (amino acid) (a) has a weight average molecular weight Mw in the range of 800 to 20,000g/mol, more preferably in the range of 1,500 to 8,000 g/mol. The weight average molecular weight of the hydroxylated polymethacrylate was determined by Size Exclusion Chromatography (SEC) using 0.1% (w/w) trifluoroacetate as solvent and 0.1M NaCl in distilled water as eluent, calibrated with poly (2-vinylpyridine) standards. Most preferably, polylysine having a molecular weight of 800 to 8,000g/mol in the aqueous formulation is used as component (A).
Component (B)
One or more components (B) capable of reacting with the poly (amino acid) (a) selected from the group consisting of reducing sugars, 1, 3-dihydroxyacetone, glycolaldehyde, glyceraldehyde, or any mixture thereof are used in the foaming mixture. Preferably, hydroxyacetone or 1, 3-dihydroxyacetone is used as component (B).
Preferably, the weight ratio of poly (amino acid) (a) to component (B) is in the range of 2:1 to 5:1.
Poly (amino acids) and reducing sugars from natural sources can be used as raw materials to produce substantially bio-based foams.
It is assumed that components a and B undergo maillard reactions. The first step is to add the free amine group of the (poly) amino acid (component (a)) to the carbonyl group of the reducing sugar (ketose/aldose) (component (B)). The glycosylamines formed are unstable and undergo a haynes/Amadori (Heyns/Amadori) rearrangement to form a haynes/Amadori compound (aldamine/ketoamine) and loss of one water molecule.
In the case of polylysine reacted with (di) hydroxyacetone, a crosslinked thermosetting brown solid material is formed.
Component (C)
Amphoteric polymers suitable as component (C) are described, for example, in WO 2004/087818 and WO 2005/012637. Preferred are copolymers comprising units derived from vinylamine and vinylformamide or units derived from vinylamine and unsaturated carboxylic acid/carboxylate, and terpolymers comprising 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. By way of example, mention may be made ofF 3000。
Component (D)
Component (D) of the system comprises one or more surfactants for forming and stabilizing the foam. Anionic, cationic, nonionic or amphoteric surfactants are useful.
Suitable anionic surfactants are diphenyl ether sulfonates, alkane sulfonates and alkylbenzene sulfonates, alkyl naphthalene sulfonates, alkene sulfonates, alkyl ether sulfonates, alkyl sulfates, alkyl ether sulfates, alpha-sulfofatty acid esters, amidoalkane sulfonates, acyl isethionates, alkyl ether carboxylates, N-acyl sarcosinates, alkyl phosphates and alkyl ether phosphates.
Useful nonionic surfactants include alkylphenol polyglycol ethers, fatty alcohol polyglycol ethers, fatty acid alkanolamides, EO-PO block copolymers, amine oxides, glycerol fatty acid esters, sorbitan esters and alkyl polyglucosides. Useful cationic surfactants include alkyl tri-ammonium salts, alkyl benzyl dimethyl ammonium salts, and alkyl pyridinium salts.
It is particularly preferred to use a mixture of anionic and nonionic surfactants.
Preferably, a mixture of an anionic surfactant and a nonionic surfactant is used as the surfactant (D). More preferably, as surfactant (D) a mixture of sodium salts of (C12-C14) fatty alcohol ether sulfates, (C12-C14) alkyl polyglycosides or mixtures thereof is used.
Preferably, the weight ratio of anionic surfactant to nonionic surfactant is in the range of 50:50 to 90:10.
Component (E)
Water was used as component (E). Preferably, components (A), (B), (C) and (D) are used in the form of aqueous solutions or dispersions. Additional water may be added to achieve the above-described composition of the mixture and to adjust the viscosity.
Component (F)
Flame retardants, fillers and salts (e.g. sodium formate, sodium acetate, sodium citrate, sodium chloride) can be used as further component (F). Preferably, a flame retardant is used as additive (F).
The subject of the invention is also a process for producing an in situ foam by preparing an aqueous solution or dispersion of the components (A) to (F) of the above-described system and foaming the aqueous solution or dispersion with a gas or gas mixture.
In situ foam may be obtained by mixing an aqueous composition comprising components (a) to (F) with a gas or gas mixture at (super) atmospheric pressure and foaming it and applying mechanical forces, such as stirring or shearing by a static mixer. The aqueous composition may also be foamed by dispersing an inert gas in the form of small bubbles of gas. The introduction of air bubbles into the aqueous composition will be achieved by beating, shaking, stirring, whipping the stator or rotor device. It is preferred to use a mixer with stator and/or rotor elements.
The gas or gas mixture used preferably comprises an inert gas, such as nitrogen, argon, carbon dioxide or oxygen. Air is particularly preferably used.
A preferred method comprises the steps of
(A) Preparing an aqueous solution or dispersion comprising components (A) to (F),
(B) The aqueous solution or dispersion is frothed by introducing a gas or gas mixture into the aqueous solution or dispersion via one or more mixing elements,
(C) Transferring the foam obtained in step (b) into a mould, and
(D) The foam is cured and dried at 50 ℃ to 160 ℃.
The subject of the invention is also a foam obtainable by the above-described process. The dried foam preferably comprises more than 50wt. -%, more preferably more than 65wt. -% of the incorporated components (a) and (B) as a reticulated matrix of the foam.
Preferably, the foam has a density in the range of 10 to 60kg/m3 as determined according to DIN 53420. The density can be adjusted by the amounts of the amphoteric polymer (component (C)) and the surfactant (component (D)). The density can be increased by using more reactive components (a) and (B) in the system used to produce the in situ foam.
Preferably, the foam has a shore hardness of 000 in the range of 20 to 80 as determined according to ASTM D2240.
The resulting air blown foam exhibits high flexibility (shore hardness) and good sound absorption properties.
Foam according to the invention
Obtainable by an air-blown foaming process
-Free of formaldehyde and isocyanate
Open-cell, wherein the open-cell content is greater than 95% as determined by optical microscopy
Is water-based
Is not brittle and exhibits a high flexibility as evidenced by a low Shore hardness value
Have good sound absorption properties and low air flow over a wide frequency range
Resistance.
Examples
Hereinafter, the present invention is described in more detail and in detail with reference to examples, which, however, are not intended to limit the present invention.
The raw materials used are as follows:
surfactant 1: anionic surfactantsFES 32 (31 wt. -% in water, fatty alcohol (C12-C14) ether (about 4 EO) sodium sulfate, BASF SE);
surfactant 2: a non-ionic surfactant which is capable of forming a free radical,GD 70 (68 wt. -%, C10-C12 alkyl polyglucoside in water);
Deionized water;
Polylysine-1 having a weight average molecular weight Mw of about 2,000g/mol (50 wt. -% in water).
Polylysine-5 having a weight average molecular weight Mw (50 wt. -% in water) of about 5,500 g/mol;
Preparation of polylysine-1 and polylysine-5 by heat treatment of L-lysine according to example 1 of WO 2022/136613
Amphoteric polyvinylamine
F3000 (11 wt. -%, NVF/VA/AA copolymer (35/35/30 mol%) in water), sonar-Basoff company (Solenis-BASF);
Crosslinking agent 1, 3-dihydroxyacetone (70 wt. -% in water, sigma Aldrich).
Determination of the weight average molecular weight M of polylysinew
Mw was determined by size exclusion chromatography under the following conditions:
● Solvent and eluent 0.1% (w/w) trifluoroacetate, 0.1M NaCl in distilled water
● Flow rate 0.8ml/min
● Sample volume 100. Mu.l
● The sample was filtered through MINISART RC (0.2 μm) filter from Sidorius, inc. (Sartorius)
● Column material hydroxylated polymethacrylate (TSKgel G3000 PWXL)
● Column size, inner diameter 7.8mm, length 30cm
● Column temperature of 35 DEG C
● Detector DRI AGILENT 1100UVGAT-LCD 503[232nm ]
● Calibration was performed with poly (2-vinylpyridine) standard (polymer Standard service Co (PSS) from Meijz (Mainz, germany)) and pyridine (79 g/mol) having a molar mass in the range of 620 to 2890000 g/mol
● The upper limit of integration is set to 29.01mL
● The calculation of Mw included lysine oligomers and polymers and monomeric lysine.
Characterization of foam
Foam density was determined in accordance with DIN 53420.
Shore hardness is measured according to ASTM D2240. For the measurement of low density foam, a scale of 000 (sphere diameter of 2.4mm, spring force of 1.111N) was used.
The sound absorption was determined by impedance tube measurement according to ISO 10534-2, with a sample thickness of 30mm and a diameter of 100mm.
The compression stress value (compression load deflection) CV 40 is measured in accordance with DIN EN ISO 3386-1.
EXAMPLE 1-EXAMPLE 12 preparation of air blown polylysine-based foam
To a mixture of surfactant 1 and surfactant 2 in water, an aqueous dispersion of polylysine and an aqueous dispersion of final amphoteric polyvinylamine were added and mixed by gentle manual shaking for a few seconds. Then, a crosslinking agent in water was added, and the whole mixture was treated with a high shear mixer (Krups Handmixer Mix 7000) at high speed for 1min. Thus, a fine-celled air-blown foam having an open cell content of greater than 95% as determined by optical microscopy is produced and poured into a suitable mold (e.g., a 10 x 5cm box). The liquid foam was cured at 100 ℃ and dried for 24h. After cooling, the now solid foam was demolded.
The composition (in parts by weight) and shore hardness 000 (23 ℃,50% relative humidity) of the foam obtained are shown in table 1. After conditioning for 24 hours at 50% relative humidity, the foam densities of the samples of examples 1-9 were determined to be in the range of 24-28kg/m3.
The foam obtained has an open cell structure (as determined by optical microscopy > 95%) and it exhibits good sound absorption in the frequency range of 100-5.000Hz, with a maximum sound absorption of about 2.000Hz, similar to the usual open cell PUR soft foams. The sound absorption of the foam obtained from example 1 is shown in table 2.
The mechanical properties after conditioning temperature and moisture at 23 ℃ at 50% relative humidity are shown in table 3. At higher tempering temperatures, the foam exhibits higher shore hardness and compressive load. Conditioning at higher relative humidity produces softer foam.
Less uniform foam may be obtained after curing without a crosslinker (example 11), with low molecular weight polylysine (example 12) or without a stable prepolymer polyvinylamine (example 10).
TABLE 1 composition and Shore hardness of the foam obtained
Table 2 sound absorption of the foam of example 1:
| Frequency [ Hz ] | Absorption rate |
| 160 | 0.067 |
| 200 | 0.089 |
| 250 | 0.116 |
| 315 | 0.133 |
| 400 | 0.177 |
| 500 | 0.221 |
| 630 | 0.256 |
| 800 | 0.376 |
| 1000 | 0.536 |
| 1250 | 0.655 |
| 1600 | 0.779 |
| 2000 | 0.968 |
| 2500 | 0.960 |
| 3150 | 0.857 |
TABLE 3 mechanical Properties after temperature and moisture Conditioning of EXAMPLE 1
| Tempering (24 h) | Conditioning (72 h) | Compression load deflection (CV 40)/kPa | Shore hardness (000) |
| 100°C | 23 ℃,50% Relative humidity | 15.3 | 40 |
| 120°C | 23 ℃,50% Relative humidity | 15.8 | 41 |
| 140°C | 23 ℃,50% Relative humidity | 24.1 | 55 |
| 160°C | 23 ℃,50% Relative humidity | 34.4 | 72 |
| 100°C | 23 ℃,80% Relative humidity | 1.9 | <5 |
| 120°C | 23 ℃,80% Relative humidity | 2.7 | <5 |
| 140°C | 23 ℃,80% Relative humidity | 2.9 | <10 |
| 160°C | 23 ℃,80% Relative humidity | 3.2 | <10 |
Comparative example C1:
To surfactant 1FES 32 (2.4 g, 31%) and surfactant 2GD 70 (0.5 g, 68%) was added to a mixture of water (22.1 g) with glyoxal (1 g, 2%) as a cross-linking agent in water and mixed by gentle shaking for a few seconds. The mixture was treated with a high shear mixer at high speed for 1min. Thereby, a fine-pore air blown foam is produced. Amphoteric polyvinylamineAqueous dispersion of F3000 (25 g, 11%) was carefully added to the foam and homogenized rapidly. The mixture was poured into a 10X 5cm box mold. The liquid foam was cured at 50 ℃ and dried for 24h. A foam density of 32kg/m3 was obtained. After cooling, the now solid foam was demolded.
The demolded free-standing flexible foam of example C1 collapsed at 23 ℃ per 50% relative humidity with a volume shrinkage of 0% after 30min, a volume shrinkage of 10% after 120min, a volume shrinkage of 18% after 210min, a volume shrinkage of 24% after 330min, and a volume shrinkage of 47% after 3 days. The demolded free-standing flexible foam of example 1 was stable under these conditions with no dimensional change.
Comparative example C2:
air blown foam made from urea-formaldehyde resin
Component A consists of 25g of a water-soluble urea-formaldehyde precondensate which is mixed with 41g of water by stirring293 Powder). When dissolved, 3g of urea was added and stirred for at least 1h. After standing for 12 hours, 15g of water was mixed. The component B consists of 4.7mL of foaming agent514 Liquid) (an aqueous solution containing 25% H3PO4 (85%), 4% resorcinol, 20% sodium bis-dimethylnaphthalene sulfonate) and 100mL of water having a pH of 1-2 was produced by stirring for 30 min. 25g of component B are treated with a high shear mixer at high speed for 1min. Thereby, a fine-pore air blown foam is produced. 47g of component A were carefully added to the foam and homogenized rapidly. The mixture was poured into a 10X 5cm box mold. The liquid foam was cured at 50 ℃ and dried for 24h. A foam density of 18.5kg/m3 was obtained. After cooling, the now solid foam was demolded.
Note that the final density of the air blown foam cannot be adjusted over a wider range than the solvent blown foam. The foam density is given by the specific blowing agent and the setting of the foaming technique. Since the same foaming technique using a high shear mixer was applied within the examples shown and comparative examples, the resulting foam density made from polylysine/dihydroxyacetone, polyvinylamine/glyoxal and urea/formaldehyde may vary depending on the chemical composition, solids content, viscosity, optimized blowing agent.
TABLE 4 mechanical Properties of example 1 and comparative example 2
This indicates that polylysine/dihydroxyacetone is a flexible, non-brittle foam. Another air blown foam based on urea-formaldehyde resins is not flexible.