Method for producing flexible polyurethane foams

Abstract

The present invention relates to a method for producing flexible polyurethane foams, wherein an isocyanate component (component B) which comprises fatty acid derivatives comprising hydroxyl groups is used as starting substance. The flexible polyurethane foams according to the invention have a bulk density according to DIN EN ISO 3386-1-98 in the range of 10 kg/m.sup.3 to 150 kg/m.sup.3, preferably 20 kg/m.sup.3 to 70 kg/m.sup.3, and in general their compressive strength according to DIN EN ISO 3386-1-98 is in the range of 0.5 kPa to 20 kPa (at 40% deformation and 4th cycle). The invention also provides an NCO-terminated prepolymer comprising urethane groups obtainable by reaction of one or more polyisocyanates (B1) with one or more fatty acid derivatives comprising hydroxyl groups (B2).

Claims

1. A method for producing a flexible polyurethane foam with a bulk density according to DIN EN ISO 3386-1-98 in the range of 10 kg/m.sup.3150 kg/m.sup.3 and a compressive strength according to DIN EN ISO 3386-1-98 in the range of 0.5 kPa to 20 kPa, at 40% deformation and 4th cycle, comprising reacting component A which is free from fatty acid derivatives comprising hydroxyl groups and which comprises A1 100 parts by weight of conventional polyether polyol, A2 2 to 5 parts by weight, based on 100 parts by weight of component A1, of water and/or physical blowing agents, A3 0.2 to 4 parts by weight, based on 100 parts by weight of component A1, of auxiliary substances and additives, A4 0.05 to 5 parts by weight, based on 100 parts by weight of component A1, of compounds having hydrogen atoms capable of reacting with isocyanates having a molecular weight of from 62 to 399, wherein the conventional polyether polyol of component A1 is an alkylene oxide addition product of a starter compound with Zerewitinoff active hydrogen atoms, with component B, which is obtained by reacting one or more polyisocyanate (B1) and one or more fatty acid derivatives comprising hydroxyl groups (B2), wherein the one or more fatty acid derivatives comprising hydroxyl groups (B2) is one or more polyricinoleic acid ester, wherein the one or more polyricinoleic acid ester is obtained by polycondensation of a monomeric ricinoleic acid and a mono- or polyhydric alcohol in the presence of at least one catalyst selected from the group consisting of sulfuric acid, p-toluenesulfonic acid, tin(II) salts, and titanium(IV) compounds, wherein the molar ratio of monomeric ricinoleic acid and the mono- or polyhydric alcohol is in a range of 3:1 to 10:1, and wherein reacting component A with component B takes place at an isocyanate index of 70 to 130.

2. The method of claim 1, wherein the conventional polyether polyol of component A1 is an alkylene oxide addition product obtained by reacting at least one starter compound selected from the group consisting of propylene glycol, ethylene glycol, diethylene glycol, dipropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, hexanediol, pentanediol, 3-methyl-1,5-pentanediol, 1,12-dodecanediol, glycerol, trimethylolpropane, triethanolamine, pentaerythritol, sorbitol, sucrose, hydroquinone, pyrocatechol, resorcinol, bisphenol F, bisphenol A, 1,3,5-trihydroxybenzene and condensates of formaldehyde and phenol comprising methylol groups, condensates of formaldehyde and melamine comprising methylol groups, and condensates of formaldehyde and urea comprising methylol groups, with at least one alkylene oxide selected from the group consisting of ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, and styrene oxide.

3. The method of claim 1, wherein the mono- or polyhydric alcohol is selected from the group consisting of n-hexanol, n-dodecanol, n-octadecanol, cyclohexanol, 1,4-dihydroxycyclohexane, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, neopentyl glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, dibutylene glycol, glycerol, and trimethylolpropane.

4. The method of claim 1, wherein the one or more polyricinoleic acid esters have an acid value of less than 4 mg KOH/g.

5. The method of claim 1, wherein the one or more polyricinoleic acid esters have a hydroxyl value of 30 mg KOH/g to 80 mg KOH/g.

6. The method of claim 1, wherein the one or more polyisocyanate (B 1) is at least one compound selected from the group consisting of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4-diphenylmethane diisocyanate, 2,4-diphenylmethane diisocyanate, 2,2-diphenylmethane diisocyanate, and polyphenyl polymethylene polyisocyanate.

7. A flexible polyurethane foam with a bulk density according to DIN EN ISO 3386-1-98 in the range of 10 kg/m3 to 150 kg/m3 and a compressive strength according to DIN EN ISO 3386-1-98 in the range of 0.5 kPa to 20 kPa, at 40% deformation and 4th cycle, obtained by the method of claim 1.

8. A method for producing a flexible polyurethane foam with a bulk density according to DIN EN ISO 3386-1-98 in the range of 10 kg/m3 to 70 kg/m3 and a compressive strength according to DIN EN ISO 3386-1-98 in the range of 0.5 kPa to 20 kPa at 40% deformation and 4th cycle, comprising reacting component A which is free from fatty acid derivatives comprising hydroxyl groups and which consists of A1 100 parts by weight of conventional polyether polyol, A2 2 to 5 parts by weight, based on 100 parts by weight of component A1, of water and/or physical blowing agents, A3 0.2 to 4 parts by weight, based on 100 parts by weight of component A1, of auxiliary substances and additives, A4 0.05 to 5 parts by weight, based on 100 parts by weight of component A1, of compounds having hydrogen atoms capable of reacting with isocyanates having a molecular weight of from 62 to 399, wherein the conventional polyether polyol of component A1 is an alkylene oxide addition product of a starter compound with Zerewitinoff active hydrogen atoms, with component B, which is obtained by reacting one or more polyisocyanates (B1) and one or more fatty acid derivatives comprising hydroxyl groups (B2), wherein reacting component A with component B takes place at an isocyanate index of 70-130.

9. The method of claim 8, wherein the one or more fatty acid derivative comprising hydroxyl groups (B2) is one or more polyricinoleic acid ester obtained by polycondensation of a monomeric ricinoleic acid and a mono- or polyhydric alcohol in the presence of at least one catalyst selected from the group consisting of sulfuric acid, p-toluenesulfonic acid, tin(II) salts, and titanium(IV) compounds.

10. The method of claim 9, wherein the molar ratio of monomeric ricinoleic acid and the mono- or polyhydric alcohol is in a range of 3:1 to 10:1.

11. The method of claim 1, wherein the conventional polyether polyol of component A1 is an alkylene oxide addition product obtained by reacting at least one starter compound selected from the group consisting of propylene glycol, ethylene glycol, diethylene glycol, dipropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, hexanediol, pentanediol, 3-methyl-1,5-pentanediol, 1,12-dodecanediol, glycerol, trimethylolpropane, triethanolamine, pentaerythritol, sorbitol, sucrose, hydroquinone, pyrocatechol, resorcinol, bisphenol F, bisphenol A, 1,3,5-trihydroxybenzene, condensates of formaldehyde and phenol comprising methylol groups, condensates of formaldehyde and melamine comprising methylol groups and condensates of formaldehyde and urea comprising methylol groups, with at least one alkylene oxide selected from the group consisting of ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, and styrene oxide, wherein the auxiliary substances and additives of component A3 are selected from the group consisting of (3-dimethylaminopropylamine) urea, 2-(2-dimethylaminoethoxy)ethanol, N,N-bis(3-dimethylaminopropyl)-N-isopropanolamine, N,N,N-trimethyl-N-hydroxyethyl bisaminoethyl ether, and 3-dimethylaminopropylamine, wherein the compounds having hydrogen atoms capable of reacting with isocyanates having a molecular weight of from 62 to 399 of component A4 are selected from the group consisting of ethanolamine, diethanolamine, triethanolamine, sorbitol and glycerol, and wherein the one or more polyisocyanate (B1) is at least one compound selected from the group consisting of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4-diphenylmethane diisocyanate, 2,4-diphenylmethane diisocyanate, 2,2-diphenylmethane diisocyanate, and polyphenyl polymethylene polyisocyanate.

12. The method of claim 1, wherein reacting component A with component B takes place at an isocyanate index of 75-115.

Description

EXAMPLES

(1) The materials and abbreviations used have the following meaning: Ricinoleic acid: Oleo Chemie. Tin(II) chloride: Aldrich DABCO (triethylenediamine; 2,2,2-diazabicyclooctane): Aldrich A1-1: Polyether polyol with an OH value of approx. 28 mg KOH/g, produced by addition of propylene oxide and ethylene oxide in a ratio of 85 to 15 using glycerol as starter with approx. 85 mole % primary OH groups. A1-2: Polyether polyol with an OH value of approx. 37 mg KOH/g, produced by addition of propylene oxide and ethylene oxide in a ratio of 27 to 73 using glycerol as starter with approx. 83 mole % primary OH groups. A3-1 Tegostab B 8681, preparation of organo-modified polysiloxanes, Evonik Goldschmidt A3-2 Addocat 105, amine catalyst from Rheinchemie A3-3 Addocat 108, amine catalyst from Rheinchemie A3-4 Urea solution (50 wt. % in water) A3-5 Tegostab B 8715LF, preparation of organo-modified polysiloxanes, Evonik Goldschmidt A3-6 Jeffcat ZR50, amine catalyst from Huntsman Corp. Europe. A3-7 Dabco NE300, amine catalyst from Air Products. A4-1 Glycerol A4-2 Diethanolamine B1-1 Mixture comprising 57 wt. % 4,4-diphenylmethane diisocyanate, 25 wt. % 2,4-diphenylmethane diisocyanate and 18 wt. % polyphenyl polymethylene polyisocyanate (polynuclear MDI) with an NCO content of 32.5 wt. %.

(2) The analyses were carried out as follows: Dynamic viscosity: MCR 51 rheometer from Anton Paar corresponding to DIN 53019. Hydroxyl value: based on the standard DIN 53240 Acid value: based on the standard DIN 53402 NCO content: based on the standard DIN 53185

(3) The bulk density was determined according to DIN EN ISO 3386-1-98.

(4) The compressive strength was determined according to DIN EN ISO 3386-1-98 (at 40% deformation and 4th cycle).

(5) The tensile strength and elongation at break were determined according to DIN EN ISO 1798.

(6) The compression sets DVR 50% (Ct) and DVR 75% (Ct) were determined according to DIN EN ISO 1856-2001-03 at 50% and 75% deformation respectively.

(7) Production of the polyricinoleic acid ester (polyricinolate) B2-1:

(8) In a 16000-liter stirrer vessel with distillation columns and an attached partial condenser, 13000 kg ricinoleic acid and 650 kg hexanediol were taken in and heated to 200 C. with stirring. During the heating phase, water of reaction was distilled off under standard pressure. When the reaction temperature was reached, a vacuum was applied. The pressure was reduced to 20 mbar within one hour. Meanwhile, the head temperature was maintained at the level of the water boiling line by means of controlling the partial condenser temperature. At a pressure of 200 mbar after 3.5 hours, 320 g of a 28% solution of tin dichloride (anhydrous) in ethylene glycol were added. At the same time, the partial condenser temperature was fixed at 60 C. In the course of the further reaction, the acid value was monitored: the acid value after a total reaction period of 24 hours was 10 mg KOH/g, after 48 hours 5 mg KOH/g, after 72 hours 3.5 mg KOH/g and after 84 hours 3.0 mg KOH/g. After a reaction period of 84 hours, the reactor contents were cooled to 130 C.

(9) Analysis of resulting polyricinoleic acid ester B2-1: Hydroxyl value: 37.5 mg KOH/g Acid value: 3.0 mg KOH/g Viscosity 850 mPas (25 C.) Catalyst concentration: 4 ppm Sn in the end product

(10) Production of the NCO terminated prepolymer comprising urethane groups B-1:

(11) 1350.0 g of component B1-1 were mixed with 133.0 g of component B2-1 for 2 min with a stirrer and then left to stand for 24 h at 25 C. Then, the resulting product was mixed for 3 min and the NCO content determined. NCO content: 29.35 wt. %

(12) Production of the NCO terminated prepolymer comprising urethane groups B-2:

(13) 1350.0 g of component B1-1 were mixed with 266.1 g of component B2-1 for 2 min with a stirrer and then left to stand for 24 h at 25 C. Then, the resulting product was mixed for 3 min and the NCO content determined. NCO content: 26.72 wt. %

(14) Production of the NCO terminated prepolymer comprising urethane groups B-3:

(15) 1350.0 g of component B1-1 were mixed with 399.2 g of component B2-1 for 2 min with a stirrer and then left to stand for 24 h at 25 C. Then, the resulting product was mixed for 3 min and the NCO content determined NCO content: 24.50 wt. %
A) Production of Flexible Polyurethane Moulded Foams

(16) In a processing method conventional for the production of flexible polyurethane moulded foams, the feed materials listed in the examples in the following table 1 are reacted with one another by the one-step method. The reaction mixture is introduced into a metal mould having a volume of 9.7 l heated to 60 C. and is demoulded after 5 min. The feed quantity of the raw materials was selected so that a calculated moulding density of about 53 kg/m.sup.3 results. Shown in table 1 is the moulding density actually obtained, which was determined in accordance with DIN EN ISO 3386-1-98.

(17) TABLE-US-00001 TABLE 1 Production and evaluation of flexible polyurethane moulded foams 1 2 (Cp.) (Cp.) 3 4 A1-1 [pts. by wt.] 82.78 86.89 91.43 90.96 A1-2 [pts. by wt.] 2.37 2.48 2.61 2.76 H.sub.2O [pts. by wt.] 3.03 3.18 3.34 3.53 B2-1 [pts. by wt.] 9.46 4.97 A4-2 [pts. by wt.] 0.95 0.99 1.04 1.10 A3-5 [pts. by wt.] 0.95 0.99 1.04 1.10 A3-6 [pts. by wt.] 0.38 0.40 0.42 0.44 A3-7 [pts. by wt.] 0.09 0.10 0.10 0.11 Index 90 90 90 90 B1-1 [MV] 48.0 B-1 [MV] 55.4 B-2 [MV] 63.6 B-3 [MV] 72.7 GSTR Poor Medium Good Good Bulk density [kg/m.sup.3] 54.6 53.7 53.5 52.7 Compressive [kPa] 5.60 5.18 5.23 4.87 strength Tensile strength [kPa] 114 112 108 105 Elongation at break [%] 102 107 104 103 Compression set Ct[%] 6.9 6.4 6.2 5.5 50% Compression set Ct[%] 8.9 9.0 8.7 7.0 75% Abbreviations: Cp. = comparative example; pts. by wt. = parts by weight; MV = weight ratio of component A to component B at given index and based on 100 parts by weight of component A; in the case of comparative examples 1 and 2, the component B2-1 (polyricinoleic acid ester) used in the polyol formulation is added to component A and thus also to the sum of the parts by weight of component A; GSTR = measure of the tear propagation resistance of the moulding immediately upon demoulding (green strength): good = no tearing of the moulding on removal of the moulding from the metal mould; medium = defects visible on the surface of the moulding; poor = tearing of the moulding on removal of the moulding from the metal mould.

(18) With the respective polyol formulation of comparative examples 1 and 2 (including component B1-1 in the polyol formulation), a phase separation was observed. In the case of comparative example 1, a second phase formed within 2 h and in the case of comparative example 2, a second phase formed within 3 h. In the respective polyol formulation of examples 3 and 4, no phase separation was observed within an observation period of 24 h.

(19) From the flexible polyurethane moulded foams according to the invention (examples 3 and 4), in which the polyricinoleic acid ester was processed in the form of a prepolymer, flexible moulded foams with good tear propagation resistance of the mouldings could be produced immediately upon demoulding. On the other hand, the flexible polyurethane moulded foams of comparative examples 1 and 2 were sensitive upon demoulding and tore and displayed considerable defects at the surface.

(20) B) Production of Flexible Polyurethane Slabstock Foams

(21) In a processing method conventional for the production of polyurethane foams, the feed materials listed in the examples in the following table 2 are reacted with one another by the one-step method.

(22) TABLE-US-00002 TABLE 2 Production and evaluation of flexible polyurethane slabstock foams 7 8 5 6 (Cp.) (Cp.) A1-1 [pts. by wt.] 93.6 94.1 85.3 80.5 B2-1 [pts. by wt.] 9.5 14.2 H.sub.2O (added) [pts. by wt.] 3.7 3.4 3.0 3.0 A3-1 [pts. by wt.] 0.1 0.1 0.0 0.0 A3-2 [pts. by wt.] 0.3 0.3 0.3 0.3 A3-3 [pts. by wt.] 0.1 0.1 0.0 0.0 A3-4 [pts. by wt.] 1.2 1.1 0.9 0.9 A4-1 [pts. by wt.] 0.6 0.5 0.5 0.5 A4-2 [pts. by wt.] 0.5 0.5 0.4 0.4 B1-1 MV 59.4 59.5 B-1 MV 94.9 B-2 MV 81.7 Index 100 100 100 100 Cream time [s] 18 17 17 18 Rise time [s] 120 115 115 115 Bulk density [kg/m.sup.3] 45.9 41.9 Compressive strength [kPa] 6.76 6.03 Tensile strength [kPa] 102 98 Elongation at break [%] 107 111 Abbreviations: Cp. = comparative example; pts. by wt. = parts by weight; MV = weight ratio of component A to component B at given index and based on 100 parts by weight of component A; in the case of comparative examples 1 and 2, the component B2-1 (polyricinoleic acid ester) used in the polyol formulation is added to component A and thus also to the sum of the parts by weight of component A; H.sub.2O (added) = added quantity of water; since component A3-4 (50% solution of urea in water) also comprises water, the total quantity of water in the polyol formulation is correspondingly higher.

(23) The flexible polyurethane slabstock foams according to the invention (examples 5 and 6), in which polyricinoleic acid ester comprised in component B (prepolymer) was used, could be produced without any problems with good mechanical properties.

(24) In a mixture produced from the constituents of component A of comparative examples 7 and 8 (including component B1-1) (polyol formulation), a phase separation was observed. In the case of comparative examples 7 and 8, a phase separation occurred after 2 h. In a mixture produced from the constituents of component A of examples 5 and 6 (polyol formulation), no phase separation was observed within an observation period of 24 h.