PRODUCTION OF PU FOAMS USING RECYCLED POLYOLS
20240368331 · 2024-11-07
Assignee
Inventors
Cpc classification
C08G18/4804
CHEMISTRY; METALLURGY
C08J9/00
CHEMISTRY; METALLURGY
C08G18/4829
CHEMISTRY; METALLURGY
C08J9/02
CHEMISTRY; METALLURGY
C08G18/7621
CHEMISTRY; METALLURGY
C08G18/18
CHEMISTRY; METALLURGY
C08G2110/0083
CHEMISTRY; METALLURGY
International classification
C08G18/18
CHEMISTRY; METALLURGY
C08J9/02
CHEMISTRY; METALLURGY
Abstract
A process for producing PU foams can be performed by reacting at least one polyol component, which contains a recycled polyol, and at least one isocyanate component in the presence of one or more catalysts that catalyze the isocyanate-polyol and/or isocyanate-water and/or isocyanate trimerization reactions. The process also has at least one foam stabilizer and optionally one or more chemical or physical blowing agents. The employed recycled polyol has a total concentration of antioxidants of formula 3a and/or formula 1d of 0.001% to 10% by weight, preferably 0.002% to 8% by weight, further preferably 0.005% to 7.5% by weight, and particularly preferably 0.01% to 5% by weight, based on the total recycled polyol.
Claims
1. A process for producing a PU foam, the process comprising: reacting (a) at least one polyol component, comprising a recycled polyol, (b) at least one isocyanate component, in the presence of (c) at least one or more catalysts that catalyse an isocyanate-polyol and/or isocyanate-water and/or isocyanate trimerization reactions, (d) at least one foam stabilizer, and also (e) optionally at least one or more chemical or physical blowing agents, wherein said recycled polyol comprises at least one antioxidant of formula 1d and/or 3a with formula 3a ##STR00008## wherein R.sup.X, R.sup.Y are independently identical or different, linear or branched alkyl substituents having 1 to 16 carbon atoms or hydrogen, and formula (1d) ##STR00009## wherein R.sup.1, R.sup.2 are independently linear or branched C.sub.1-C.sub.8 alkyl, q is 1, 2 or 3, n is an integer from 1 to 4, R.sup.3 is a linear or branched C.sub.1-C.sub.30 alkyl or C.sub.2-C.sub.30 alkyl, which are in each case optionally interrupted by one or more oxygen atoms, k is an integer between 0 and 10, m is an integer between 0 and 10, (k+m) is an integer between 0 and 20, wherein a total concentration of the at least one antioxidant of formula 3a and/or formula 1d in the recycled polyol is 0.001% to 10% by weight based on a total recycled polyol.
2. The process according to claim 1, wherein the at least one antioxidant of formula 3a and/or formula 1d is selected from the group consisting of 4,4-dioctyldiphenylamine, 4,4-dibutyldiphenylamine, 4-butyl-4-octyldiphenylamine, heptyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate, octyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate, nonyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate, tridecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate, tetradecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate, pentadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate, and/or pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate).
3. The process according to claim 1, wherein the recycled polyol optionally comprises at least one further antioxidant selected from the following group consisting of: (i) 2-(2-hydroxyphenyl)benzotriazoles, (ii) 2-hydroxybenzophenones, (iii) non-phenolic benzoic acids and/or benzoates, (iv) tannins and/or phenols, with the proviso that these do not correspond to the above formula 1d, (v) benzofuranones, triazines, 2,2,6,6-tetramethylpiperidines, hydroxylamines, alkyl and aryl phosphites, sulfides, zinc carboxylates, and diketones.
4. The process according to claim 1, wherein the PU foam is a rigid PU foam, a flexible PU foam, a hot-cure flexible PU foam, a viscoelastic PU foam, an HR PU foam, a hypersoft PU foam, a semirigid PU foam, a thermoformable PU foam, or an integral PU foam.
5. The process according to claim 1, wherein the reaction is carried out using f) water, g) one or more organic solvents, h) one or more flame retardants, and/or i) one or more further additives.
6. The process according to claim 1, wherein the at least one foam stabilizer is selected from the group consisting of silicon compounds that include carbon atoms, compounds described by the formula (1c), and mixtures of two or more of said compounds:
[R.sup.1.sub.2R.sup.2SiO.sub.1/2].sub.a[R.sup.1.sub.3SiO.sub.1/2].sub.b[R.sup.1.sub.2SiO.sub.2/2].sub.c[R.sup.1R.sup.2SiO.sub.2/2].sub.d[R.sup.3SiO.sub.3/2].sub.e[SiO.sub.4/2].sub.fG.sub.g Formula (1c) wherein a=0 to 12, b=0 to 8, c=0 to 250, d=0 to 40, e=0 to 10, f=0 to 5, g=0 to 3, where:
(O.sub.1/2).sub.nSiR.sup.1.sub.mCH.sub.2CHR.sup.5R.sup.4CHR.sup.5CH.sub.2SiR.sup.1.sub.m(O.sub.1/2).sub.n,
(O.sub.1/2).sub.nSiR.sup.1.sub.mCH.sub.2CHR.sup.5R.sup.4CR.sup.5CH.sub.2,
(O.sub.1/2).sub.nSiR.sup.1.sub.mCH.sub.2CHR.sup.5R.sup.4CR.sup.5CR.sup.5CH.sub.3, R.sup.4=independently identical or different divalent organic radicals, optionally interrupted by ether, ester or amide groups and optionally functionalized with OH groups, or (SiR.sup.1.sub.2O).sub.xSiR.sup.1.sub.2, x=1 to 50, R.sup.5=independently identical or different alkyl radicals consisting of 1 to 16 carbon atoms, aryl radicals having 6 to 16 carbon atoms, or hydrogen, wherein: n=1 or 2, m=1 or 2, n+m=3, R.sup.1=identical or different radicals selected from the group of saturated or unsaturated alkyl radicals having 1 to 16 carbon atoms, aryl radicals having 6 to 16 carbon atoms, hydrogen, OR.sup.6, R.sup.2=independently identical or different polyethers obtainable by the polymerization of ethylene oxide, propylene oxide, and/or other alkylene oxides having the general formula (2) or an organic radical corresponding to formula (3)
(R.sup.7).sub.hO[C.sub.2H.sub.4O].sub.i[C.sub.3H.sub.6O].sub.j[CR.sup.8.sub.2CR.sup.8.sub.2O].sub.kR.sup.9, (2)
O.sub.hR.sup.10, (3) wherein h=0or 1, R.sup.7=divalent organic radical, optionally substituted with OR.sup.6, i=0 to 150, j=0 to 150, k=0 to 80, p=1-18, wherein
7. The process according to claim 1, wherein the at least one or more catalyst for production of the PU foam is selected from triethylenediamine, 1,4-diazabicyclo[2.2.2]octane-2-methanol, diethanolamine, N-[2-[2-(dimethylamino)ethoxy]ethyl]-N-methyl-1,3-propanediamine, 2-[[2-(2-(dimethylamino)ethoxy)ethyl]methylamino]ethanol, 1,1-[(3-{bis[3-(dimethylamino)propyl]amino}propyl)imino]dipropan-2-ol, [3-(dimethylamino)propyl]urea, 1,3-bis[3-(dimethylamino)propyl]urea, amine catalysts of general structure (1a) or of structure (1b): ##STR00010## wherein X comprises oxygen, nitrogen, hydroxyl, amino groups of the structure NR.sup.III or NR.sup.IIIR.sup.IV or urea groups (N(R.sup.V)C(O)N(R.sup.VI) or N(R.sup.VII)C(O)NR.sup.VIR.sup.VII), Y comprises amino groups NR.sup.VIIIR.sup.IX or alkoxy groups OR.sup.IX, R.sup.I,II comprise identical or different, linear or cyclic, aliphatic or aromatic hydrocarbon groups having 1-8 carbon atoms that are optionally functionalized with an OH group and/or comprise hydrogen, R.sup.III-IX comprise identical or different, linear or cyclic, aliphatic or aromatic hydrocarbon groups having 1-8 carbon atoms that are optionally functionalized with an OH group, an NH or NH.sub.2 group, and/or comprise hydrogen, m=0 to 4, n=2 to 6, i=0 to 3, ##STR00011## wherein R.sup.X comprises identical or different radicals consisting of hydrogen and/or linear, branched, or cyclic, aliphatic or aromatic hydrocarbon groups having 1-18 carbon atoms, which may be substituted with 0-1 hydroxyl groups and 0-1 NH.sub.2 groups, Z comprises oxygen, NR.sup.X or CH.sub.2, and/or metal compounds including organometallic metal salts. organic metal salts, inorganic metal salts, organometallic compounds of the metals Sn, Bi, Zn, Al or K or mixtures thereof.
8. The process according to claim 1, wherein, based on a total of the at least one polyol component, more than 30% by weight of recycled polyol is used, and the total concentration of the at least one antioxidant of formula 3a and/or formula 1d in the recycled polyol is 0.001% to 10% by weight based on the total recycled polyol.
9. The process according to claim 1, wherein the recycled polyol was obtained from a polyurethane hydrolysis comprising the reaction of the polyurethane with water in the presence of a base-catalyst combination (I) or (II), where (I) comprises a base having a pK.sub.b at 25 C. of 1 to 10 and at least one catalyst selected from the group consisting of quaternary ammonium salts containing an ammonium cation comprising 6 to 30 carbon atoms and organic sulfonates containing at least 7 carbon atoms, or where (II) comprises a base having a pK.sub.b at 25 C. of <1 and at least one catalyst selected from the group consisting of quaternary ammonium salts containing an ammonium cation having 6 to 14 carbon atoms in the case of an ammonium cation that does not contain a benzyl substituent, and quaternary ammonium salts containing an ammonium cation having 6 to 12 carbon atoms in the case of an ammonium cation that contains a benzyl substituent.
10. A composition suitable for production of a polyurethane foam, comprising at least one polyol component that comprises a recycled polyol, at least one isocyanate component, a catalyst, a foam stabilizer, a blowing agent, and optionally auxiliaries, wherein the recycled polyol comprises at least one antioxidant of formula 1d and/or 3a with formula 3a ##STR00012## wherein R.sup.X, R.sup.Y are independently identical or different, linear or branched alkyl substituents having 1 to 16 carbon atoms or hydrogen, and formula (1d) ##STR00013## wherein R.sup.1, R.sup.2 are independently straight-chain or branched C.sub.1-C.sub.8 alkyls, q is 1, 2 or 3, n is an integer from 1 to 4, R.sup.3 is a linear or branched C.sub.1-C.sub.30 alkyl or C.sub.2-C.sub.30 alkyl, which are in each case optionally interrupted by one or more oxygen atoms, k is an integer between 0 and 10, m is an integer between 0 and 10, (k+m) is an integer between 0 and 20, wherein a total concentration of the at least one antioxidant of formula 3a and/or formula 1d in the recycled polyol is 0.001% to 10% by weight based on the total recycled polyol.
11. A polyurethane foam, which is obtained by a process according to claim 1.
12. A method for manufacturing products containing a PU foam, the method comprising: constructing the products with a PU foam according to claim 11, and wherein the products comprise refrigerator insulation, insulation panels, sandwich elements, pipe insulation, imitation wood, mattresses, furniture cushioning, automotive seat cushioning, headrests, instrument panels, automotive interior trim, automotive headlining, sound absorption material, steering wheels, shoe soles, carpet backing foam, and filter foams.
13. The process according to claim 1, wherein the total concentration of the at least one antioxidant of formula 3a and/or formula 1d in the recycled polyol is 0.01% to 5% by weight, based on the total recycled polyol.
14. The process according to claim 3, wherein the 2-(2-hydroxyphenyl)benzotriazole is 2-(2-hydroxy-5-methylphenyl)benzotriazole and/or 2-(2-hydroxy-3,5-di-tert-butylphenyl)benzotriazole.
15. The process according to claim 3, wherein the benzofuranone is described by formula (1e) ##STR00014## wherein n is an integer between 0 and 7, R.sup.6, R.sup.7 are independently hydrogen or a C.sub.1-C.sub.8 alkyl, and R.sup.8 is hydrogen or an aromatic radical.
16. The process according to claim 4, wherein the PU foam is a hot-cure flexible PU foam.
17. The process according to claim 5, wherein the one or more further additives are selected from the group consisting of surfactants, biocides, dyes, pigments, fillers, antistatic additives, crosslinkers, chain extenders, cell openers, and fragrances.
18. The process according to claim 6, wherein a=0 to 8, b=0 to 2, c=1.5 to 150, d=0 to 20, e=0 to 6, f=0, and g=0 to 2.
19. The process according to claim 6, wherein i=0 to 150, j=0 to 150, k=0 to 80, and p=1-18.
20. The process according to claim 7, wherein m=2 or 3, n=2 or 3, and i=0-2.
Description
EXAMPLES
Production of Recycled Polyols
Recycled Polyol 1 (Inventive)
[0219] The recycled polyol 1 of the invention was obtained by hydrolysis of polyurethane in the presence of a saturated K.sub.2CO.sub.3 solution and tetrabutylammonium chloride as catalyst:
[0220] A reactor from Parr (Parr Instrumental Company) equipped with a PTFE inner container and a mechanical stirrer was filled with 25 g of compressed foam pieces (approx. 1 cm1 cm). The polyurethane foam used was produced according to formulation 1, in which the conventional polyol Arcol 1104 had been used. To this was then added 75 g of saturated K.sub.2CO.sub.3 solution (pK.sub.b 3.67 at 25 C.). The tetrabutylammonium chloride catalyst was then added to a content of 5% by weight based on the mass of the reaction mixture. The reactor was closed and the reaction mixture was heated to an internal temperature of 150 C. for 14 hours. At the end of the 14 hours, heating was stopped and the reaction mixture was cooled to room temperature. After opening the reactor, the reaction mixture was transferred to a round-bottomed flask. The water was removed by rotary evaporation and the residual reaction mixture was extracted with cyclohexane. The cyclohexane solution was washed with 1 N aqueous HCl solution and then dried over magnesium sulfate. Removal of the cyclohexane by rotary evaporation afforded the recycled polyol 1 in the form of a liquid. The hydrolysis process was repeated so as to provide a sufficiently large amount of recycled polyol for the foaming experiments.
[0221] The total antioxidant concentration of the recycled polyol 1 was 0.18% by weight, determined from the sum total of the individual components 4,4-dioctyldiphenylamine, 4,4-dibutyldiphenylamine and 4-butyl-4-octyldiphenylamine.
Recycled Polyol 2 (Inventive)
[0222] The recycled polyol 2 of the invention was obtained by hydrolysis of polyurethane in the presence of a 30% sodium silicate solution and tributylmethylammonium chloride as catalyst:
[0223] A reactor from Parr (Parr Instrumental Company) equipped with a PTFE inner container and a mechanical stirrer was filled with 25 g of compressed foam pieces (approx. 1 cm1 cm). The polyurethane foam used was produced according to formulation 1, in which the conventional polyol Arcol 1104 had been used. To this was then added 75 g of sodium silicate solution (30% by weight solution in water).
[0224] The tributylmethylammonium chloride catalyst was then added to a content of 2.5% by weight based on the mass of the reaction mixture. The reactor was closed and the reaction mixture was heated to an internal temperature of 150 C. for 10 hours. At the end of the 10 hours, heating was stopped and the reaction mixture was cooled to room temperature. After opening the reactor, the reaction mixture was transferred to a round-bottomed flask. The water was removed by rotary evaporation and the residual reaction mixture was extracted with cyclohexane. The cyclohexane phase was washed with 1 N aqueous HCl solution and then dried over magnesium sulfate. Removal of the cyclohexane by rotary evaporation afforded the recycled polyol 2 in the form of a liquid. The hydrolysis process was repeated so as to provide a sufficiently large amount of recycled polyol for the foaming experiments.
[0225] The total antioxidant concentration of the recycled polyol 2 was 0.20% by weight, determined from the sum total of the individual components 4,4-dioctyldiphenylamine, 4,4-dibutyldiphenylamine and 4-butyl-4-octyldiphenylamine.
Production of the Glycerol Polyether polyol 1 by Classical Alkoxylation
[0226] A 3 L autoclave was charged with 500.0 g of glycerol and 102.0 g of aqueous potassium hydroxide solution (45%) was added. The mixture was heated to 95 C. and stirred at this temperature for 45 minutes. The mixture was then heated to 120 C. and the pressure was reduced to 30 mbar. Volatiles were removed by distillation over a period of 80 minutes. The reaction mixture was then cooled to room temperature.
[0227] A 1 L autoclave was charged with 360.0 g of the product obtained in the previous step. The reactor contents were inertized by evacuating and releasing the vacuum with nitrogen several times. The reactor was then heated to 115 C. with stirring and evacuated to an internal pressure of 30 mbar. A total of 624 g of propylene oxide was metered in over a period of 70 minutes at a pressure of max. 1.2 bar. At the end of the propylene oxide addition, stirring was continued for a further hour at 115 C. to allow further reaction, after which volatiles were distilled off at 95 C. under reduced pressure for 15 minutes. The mixture was cooled to room temperature.
[0228] A 3 L autoclave was charged with 155.9 g of the product obtained in the previous step. The reactor contents were inertized by evacuating and releasing the vacuum with nitrogen several times. The reactor was then heated to 115 C. and evacuated to an internal pressure of 30 mbar. Over a period of 13 hours, a total of 1771 g of propylene oxide was metered in within a pressure range of max. 2.5 bar reactor internal pressure. At the end of the propylene oxide addition, stirring was continued for a further 6 hours at 115 C. At the end of the further reaction period, volatiles were removed by distillation at 95 C. over a period of 30 minutes. The reaction mixture was neutralized with 100 g of 25% phosphoric acid. Water was removed by distillation under reduced pressure and precipitated salts were filtered off.
[0229] A total of 1900 g of the glycerol polyether polyol 1 was obtained. The polyether obtained has an OH value of 59 mg KOH/g and does not contain any antioxidants.
Determination of the Antioxidant Content in Polyols
[0230] The proportion by mass of the antioxidant of the invention according to the criteria of claim 1, for example the proportion by mass of (C.sub.7-C.sub.9 alkyl) 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate and/or (C.sub.13-C.sub.15 alkyl) 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate and/or octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate and/or pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate) and/or 4,4-dioctyldiphenylamine, 4,4-dibutyldiphenylamine and/or 4-butyl-4-octyldiphenylamine, is determined in the context of the present invention by HPLC. Unless otherwise indicated, all stated percentages (%) are percentages by weight.
[0231] For this, 500 mg of the polyol of the invention is dissolved in 10 ml of ethanol. An aliquot of the solution is analysed by HPLC. The analysis is carried out using an HPLC system equipped as follows: [0232] Instrument: LC Agilent 1260 [0233] Column: Agilent Zorbax Eclipse XDB-C8 150 mm*4.6 mm; 5 [0234] Column temperature: 40 C. [0235] Eluent: A: H.sub.2O [0236] B: Ethanol [0237] Injected volume: 3 l [0238] Detector: DAD 280 nm [0239] Flow: 1 ml/min [0240] Gradient:
TABLE-US-00002 Time [min] B [%] 0 75 10 95 15 95 16 75 20 75 [0241] Analysis time: 22 min
[0242] The one or more respective antioxidants are separated from the matrix and from one another on the basis of differences in polarity.
[0243] For the evaluation, an external calibration with standard solutions is carried out with the respective antioxidants, for example (C.sub.7-C.sub.9 alkyl) 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate and/or (C.sub.13-C.sub.15 alkyl) 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate and/or octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate and/or pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate) and/or 4,4-dioctyldiphenylamine, 4,4-dibutyldiphenylamine and/or 4-butyl-4-octyldiphenylamine, and a calibration curve is generated. Through evaluation of the peak areas, it is established which antioxidants are present in the respective sample and then the concentration of the analytes in the sample is determined.
Thermogravimetric Analyses of Recycled Polyols
[0244] The thermogravimetric analyses were carried out on a Discovery TGA from TA Instruments. The weight of sample is within a range from 15 to 25 mg in a platinum crucible. The measurements were unless otherwise described carried out for 4 h at 180 C. (temperature program T1) under an air flow of 30 ml/min. [0245] T1: 1. Equilibrate at 30.00 C.; 2. Heat at 50.00 C./min to 180.00 C.; 3. Hold the temperature for 240.00 min.
TABLE-US-00003 TABLE 1 Thermogravimetric analysis of recycled polyols at temperature program T1, 4 h 180 C.; antioxidant 1: mixture of 4,4- dioctyldiphenylamine, 4,4-dibutyldiphenylamine and 4-butyl-4- octyldiphenylamine (e.g. Irganox 5057*.sup.)), antioxidant 2: octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate (e.g. Irganox 1076**.sup.)) Content of Content of Time of Time of Time of Time of antioxidant antioxidant onset (T1 5% loss 10% loss 20% loss 1 in polyol 2 added 180 C., of mass of mass of mass Polyol [wt %] [wt %] air) [min] [min] [min] [min] Arcol 1104 0.18 66.1 69.6 77.2 89.9 Arcol 1104 0.18 (under nitrogen) Polyol 1 8.3 13.3 22.5 without antioxidants Recycled 0.18 57.7 55.6 64.9 76.4 polyol 1 Recycled 0.18 0.05 74.7 65.0 77.5 92.9 polyol 1 Recycled 0.20 91.4 88.2 99.0 113.1 polyol 2 *.sup.)Irganox 5057, antioxidant consisting of a mixture of 4,4-dioctyldiphenylamine, 4,4-dibutyldiphenylamine and 4-butyl-4-octyldiphenylamine, obtainable from BASF **.sup.)Irganox 1076, antioxidant consisting of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate, obtainable from BASF
[0246] The conventional polyol Arcol 1104 is stable in air at a temperature of 180 C. for one hour. At approximately the time at which a 5% loss of mass is exceeded after 69.6 min, a pronounced loss of mass over a period of a few minutes commences. In the analogously performed measurement under a nitrogen atmosphere, the loss of mass in Arcol 1104 over the entire measurement time of 4 hours is only 0.7%, the explanation for which being that the mass loss occurs only through a degradation reaction that takes place with oxygen. In polyol 1 produced in conventional manner by alkoxylation but not stabilized by antioxidants, the degradation process commences immediately at the start of the measurement time, with the result that a 5% loss of mass occurs after just 8.3 minutes and a 20% loss of mass after just 22.5 minutes. The recycled polyol 1 of the invention already has a content of 0.178% by weight of antioxidant 1 on being obtained from the recycling process. The loss of mass (5% after 55.6 min) commences a little earlier than with Arcol 1104, which indicates a slightly reduced thermal durability compared to its original polyol Arcol 1104. Addition of 0.05% by weight of antioxidant 2 brings a clear improvement in the thermal durability of recycled polyol 1, with the result that the loss of mass now commences later than in the case of Arcol 1104. Surprisingly, the thermal durability is particularly high in the case of recycled polyol 2, which under the measurement conditions (180 C., air) does not show a 5% loss of mass until after 88.2 minutes Recycled polyol 2 thus exceeds the thermal durability of the corresponding original polyol Arcol 1104 considerably.
General Procedure for Production of Hot-Cure Flexible PU Foams
[0247] The polyurethane foams were produced in the laboratory in the form of what are called handmade foams. The production of the foams was carried out at 22 C. and air pressure of 762 mmHg according to the details below. The polyurethane foams according to formulation 1 were in each case produced using 300 g of polyol. The other formulation constituents were adjusted accordingly. This meant, for example, that 1.0 part (1.0 pphp) of a component refers to 1 g of said substance per 100 g of polyol.
TABLE-US-00004 TABLE 1 Formulation for production of hot-cure flexible PU foams Formulation 1 Parts by mass (pphp) Polyol.sup.1) 100 pphp Water 4.00 pphp Kosmos T9.sup.2) 0.20 pphp Dabco DMEA.sup.3) 0.15 pphp Tegostab BF2370.sup.4) 1.0 pphp Desmodur T 80.sup.5) Variable, constant index of 105 .sup.1)Polyol: Standard polyether polyol Arcol 1104 obtainable from Covestro. This is a glycerol-based polyether polyol having an OH value of 56 mg KOH/g and a number-average molar mass of 3000 g/mol and a content of 0.18% of antioxidant (mixture of 4,4-dioctyldiphenylamine, 4,4-dibutyldiphenylamine and 4-butyl-4-octyldiphenylamine) or recycled polyols of the invention or non-inventive recycled polyol. The recycled polyols are produced from hot-cure flexible PU foams via a chemical recycling process. The recycling processes respectively used for production of the recycled polyol of the invention and of the non-inventive recycled polyol have already previously been described. .sup.2)Kosmos T9, obtainable from Evonik Industries: tin(II) salt of 2-ethylhexanoic acid. .sup.3)Dabco DMEA: dimethylethanolamine, available from Evonik Industries. Amine catalyst for production of polyurethane foams .sup.4)Polyether-modified polysiloxane, available from Evonik Industries. .sup.5)Toluene diisocyanate T 80 (80% 2,4-isomer, 20% 2,6-isomer) from Covestro, 3 mPa .Math. s, 48% NCO, functionality 2.
[0248] For the foams according to formulation 1, a paper cup was initially charged with the tin catalyst tin(II) 2-ethylhexanoate, polyol, the water, the amine catalysts and the respective foam stabilizer, and the contents were mixed with a disc stirrer at 1000 rpm for 60 s. After the first stirring, the isocyanate was added and incorporated with the same stirrer at 2500 rpm for 7 s and the reaction then immediately transferred to a paper-lined box (30 cm30 cm base area and 30 cm height). After the foam had been poured in, it rose up in the foaming box. In the ideal case, the foam blew off on reaching the maximum rise height and then receded slightly. This opens the cell membranes of the foam bubbles to afford an open-pore cell structure in the foam.
[0249] To assess the properties, the following characteristic parameters were in the following section determined.
Performance Tests
[0250] The foams produced were assessed on the basis of the following physical properties [0251] a) Settling of the foam at the end of the rise phase (=fall-back): [0252] The settling, or the further rise, is calculated as the difference in the foam height immediately after blow-off and after 3 minutes after foam blow-off. The foam height is measured at the maximum in the centre of the foam crest by means of a needle secured to a centimetre scale. A positive value here describes the settling of the foam after blow-off; a negative value correspondingly describes the further rise of the foam. [0253] b) Foam height is the height of the freely risen foam formed after 3 minutes. The foam height is reported in centimetres (cm). [0254] c) Rise time [0255] The period of time between the end of mixing of the reaction components and the blow-off of the polyurethane foam The rise time is reported in seconds (s). [0256] d) Porosity [0257] The air permeability of the foam was determined based on DIN EN ISO 4638:1993-07 by a dynamic pressure measurement on the foam. The measured dynamic pressure was reported in mm water column, lower dynamic pressure values being characteristic of a more open foam. The values were measured within a range from 0 to 300 mm water column. The dynamic pressure was measured by means of an apparatus comprising a nitrogen source, reducing valve with pressure gauge, flow-regulating screw, wash bottle, flowmeter, T-piece, applicator nozzle and a graduated glass tube filled with water. The applicator nozzle has an edge length of 100100 mm, a weight of 800 g, an internal diameter at the outlet opening of 5 mm, an internal diameter at the lower applicator ring of 20 mm and an external diameter at the lower applicator ring of 30 mm. [0258] The measurement is carried out by setting the nitrogen inlet pressure to 1 bar by adjusting the reducing valve and setting the flow rate to 480 l/h. The amount of water in the graduated glass tube is set so that no pressure difference builds up and none can be read off. For the measurement on the test specimen having dimensions of 25025050 mm, the applicator nozzle is applied to the corners of the test specimen, flush with the edges, and also once to the (estimated) centre of the test specimen (in each case on the side having the greatest surface area). The result is read off when a constant dynamic pressure has been established. The evaluation is based on the calculated average of the five measurements obtained. [0259] e) Number of cells per cm (cell count): This is determined visually on a cut surface (measured to DIN EN 15702:2009-04). [0260] f) Hardness CLD 40% to DIN EN ISO 3386-1:1997+A1:2010 Measured values are reported in kilopascals (kPa). [0261] g) Compression set [0262] Five test specimens having dimensions of 5 cm5 cm2.5 cm were in each case cut out of the finished foams. The starting thickness was measured. Compression set was measured no earlier than 72 h after production in accordance with DIN EN ISO 1856:2018-11. The test specimens were placed between the plates of the deforming device and were compressed by 90% of their thickness (i.e. to 2.5 mm). Within 15 minutes, the test specimens were placed in an oven at 70 C. and left therein for 22 h. At the end of this time, the apparatus was removed from the oven, the test specimens were removed from the apparatus within 1 min, and they were placed on a wood surface. After relaxing for 30 min, the thickness was measured again and the compression set was calculated. The results are reported in per cent according to the following formula: DVR=(d0dr)/d0100% [0263] h) Tensile strength and elongation at break to DIN EN ISO 1798:2008-2008-04. Measured values for tensile strength are reported in kilopascals (kPa) and measured values for elongation at break in per cent (%). [0264] i) Rebound resilience to DIN EN ISO 8307:2008-03. Measured values are reported in per cent (%).
TABLE-US-00005 TABLE 3 Foaming results for the hot-cure flexible PU foams produ.ced according to formulation 1, Table 1, using recycled polyols 1 and 2 and the conventional polyol Arcol 1104; antioxidant 1: mixture of 4,4-dioctyldiphenylamine, 4,4-dibutyldiphenylamine and 4-butyl-4-octyldiphenylamine. Foam specimen #1 #2 #3 Arcol 1104, OH value 56, 100 30 reference, 0.18% by weight of antioxidant 1, (pphp) Recycled polyol 1, OH value 100 54 (inventive), contains 0.18% by weight of antioxidant 1, (pphp) Recycled polyol 2, OH value 70 60 (inventive), contains 0.20% by weight of antioxidant 1, (pphp) Index 105 105 105 Rise time (s) 117 122 122 Foam height (cm) 24.0 24.1 24.0 Settling (cm) 0.2 0.2 0.0 Cell count (cm.sup.1) 14 14 14 Porosity (mm water column) 15 10 8 Hardness CLD 40% (kPa) 3.4 3.5 3.7 Elongation at break (%) 159 148 157 Tensile strength (kPa) 113 116 128 Rebound resilience (%) 43.2 43.2 42.5 Compression set 90%, 22 h 5.2 7.5 6.9 at 70 C. (%)
[0265] The results in Table 3 compare the foamings of recycled polyols 1 and 2 of the invention with those of the conventional polyol Arcol 1104, which represents the original polyol of recycled polyols 1 and 2, since this had been used for the production of the foams from which recycled polyols 1 and 2 had been obtained. The comparison of the properties of foams #1 and #2 shows that recycled polyol 1 of the invention affords a foam comparable to that of reference foam #1 obtained from Arcol 1104. The use of 70 pphp of recycled polyol 2 together with 30 pphp of reference polyol Arcol 1104 permits the production of foam #3, the properties of which correspond essentially to those of foams #1 and #2.