METHOD FOR PRODUCING A RIGID POLYURETHANE FOAM

Abstract

The present invention relates to a process for the production of a rigid polyurethane foam or rigid polyisocyanurate foam, comprising the reaction of at least one polyisocyanate and of a polyol composition (PZ), where the polyol composition (PZ) comprises at least one compound having at least two hydrogen atoms reactive toward isocyanate groups and at least one compound (I) selected from the group consisting of dicarboxylic diesters of dicarboxylic acids having from 2 to 18 C atoms and tricarboxylic triesters of tricarboxylic acids having from 3 to 18 C atoms, where at least one blowing agent is used during the reaction. The present invention further relates to rigid polyurethane foams or rigid polyisocyanurate foams obtainable or obtained by such a process, and also to a polyol composition (PZ) at least comprising one compound having at least two hydrogen atoms reactive toward isocyanate groups and at least one compound (I) selected from the group consisting of dicarboxylic diesters of dicarboxylic acids having from 2 to 18 C atoms and tricarboxylic triesters of tricarboxylic acids having from 3 to 18 C atoms. The present invention also relates to the use of such a polyol composition (PZ) for the production of rigid polyurethane foams or rigid polyisocyanurate foams, and also to the use of a rigid polyurethane foam or rigid polyisocyanurate foam of the invention as, or for the production of, insulation materials, preferably insulation sheets, sandwich elements, hot-water tanks, boilers, coolers, insulation foams, refrigerators or freezers.

Claims

1. A process for the production of a rigid polyurethane foam or rigid polyisocyanurate foam, comprising the reaction of a) at least one polyisocyanate and b) a polyol composition (PZ), where the polyol composition (PZ) comprises at least one compound having at least two hydrogen atoms reactive toward isocyanate groups and at least one compound (I) selected from the group consisting of dicarboxylic diesters of formula: ##STR00004## where R1 and R2 are mutually each independently H or an alkyl moiety having from 1 to 6 C atoms; R.sub.3 and R.sub.4 are mutually each independently an alkyl moiety having from 1 to 18 C atoms; where at least one blowing agent is used during the reaction; where the blowing agent comprises water or water in a mixture with another physical or chemical blowing agent; and where the other blowing agent, if present, is selected from the group consisting of propane, n-butane, iso- and cyclobutane, n-, iso- and cyclopentane, cyclohexane, dimethyl ether, methyl ethyl ether, methyl butyl ether, methyl formate, acetone, 1,3,3,3-tetrafluoropropene, 1,1,1,2,3-pentafluoropropene, 1,1,1,4,4,4-hexafluorobutene and 1-chloro-3,3,3-trifluoropropene.

2. The process according to claim 1, where the polyol composition (PZ) comprises the at least one blowing agent.

3-5. (canceled)

6. The process according to claim 1, where the compound (I) is selected from the group consisting of malonic diesters.

7. The process according to claim 1, where the compound (I) is selected from the group consisting of dimethyl malonate, diethyl malonate, dipropyl malonate, dibutyl malonate, dipentyl malonate, dihexyl malonate, methyl ethyl malonate, methyl propyl malonate, methyl butyl malonate, methyl pentyl malonate, methyl hexyl malonate, ethyl propyl malonate, ethyl butyl malonate, ethyl pentyl malonate, ethyl hexyl malonate, propyl butyl malonate, propyl pentyl malonate, propyl hexyl malonate, butyl pentyl malonate, butyl hexyl malonate and pentyl hexyl malonate.

8. The process according to claim 1, where a quantity of the compound (I) used is in a range from 0.5 to 10% by weight, based on a weight of the polyol composition (PZ).

9. The process according to claim 1, where the polyol composition (PZ) comprises at least one fatty acid or one fatty acid ester or a mixture thereof.

10. The process according to claim 1, where the polyol composition (PZ) comprises castor oil.

11. The process according to claim 1, where blowing agent comprises a quantity of water in [[the]] a range from 0.1 to 10% by weight, based on a weight of the polyol composition (PZ).

12. A rigid polyurethane foam or rigid polyisocyanurate foam, obtained by the process according to claim 1.

13. A polyol composition (PZ) comprising at least one compound having at least two hydrogen atoms reactive toward isocyanate groups and at least one compound (I) selected from the group consisting of dicarboxylic diesters of formula: ##STR00005## where R1 and R2 are mutually each independently H or an alkyl moiety having from 1 to 6 C atoms; R.sub.3 and R.sub.4 are mutually each independently an alkyl moiety having from 1 to 18 C atoms; where the polyol composition (PZ) comprises at least one blowing agent comprising water or water in a mixture with another physical or chemical blowing agent; and where the other blowing agent, if present, is selected from the group consisting of propane, n-butane, iso- and cyclobutane, n-, iso- and cyclopentane, cyclohexane, dimethyl ether, methyl ethyl ether, methyl butyl ether, methyl formate, acetone, 1,3,3,3-tetrafluoropropene, 1,1,1,2,3-pentafluoropropene, 1,1,1,4,4,4-hexafluorobutene and 1-chloro-3,3,3-trifluoropropene.

14-15. (canceled)

16. An insulation sheet, sandwich element, hot-water tank, boiler, cooler, insulation foam, refrigerator or freezer which comprises, as an insulation material, the rigid polyurethane foam or rigid polyisocyanurate foam according to claim 12.

Description

EXAMPLES

1. Measurement Methods

1.1 Adhesion Measurements:

[0107] Unless otherwise stated, adhesion of the polyurethane foam to metal surfaces was measured by using a box mold measuring 20020080 mm.sup.3 lined with aluminum-coated paper at a mold temperature of 35 C. The foam is applied to the aluminum-coated surface. After introduction of the reaction mixture, the mold is closed and, unless otherwise stated, the test sample is demolded after 7 min. A blade is then used to make incisions separated by 6 cm in the aluminum-coated side of the test sample facing toward the basal side of the mold. Unless otherwise stated, adhesion was determined 3 min after demolding, i.e. after a total of 10 min, with the aid of a tensile tester, the coated paper being peeled by way of a deflector roller at a tensile testing velocity of 100 mm/min perpendicularly to the plane of the molding, and the average force required for this purpose being measured.

1.2 Determination of the Phase-Stability of the Polyol Component:

[0108] The individual constituents of the polyol component were mixed thoroughly with the blowing agent, and then freed from incorporated air bubbles in an ultrasound bath, and stored in sealed test tubes at room temperature. The phase stability is the period for which the mixture can be stored at room temperature without any visually discernible clouding of, or phase-separation of, the component.

1.3 Determination of the Brittleness of the Rigid Foams:

[0109] Brittleness is determined qualitatively by use of the thumb to make an impression in the periphery of the foam. In brittle foams, even slight deformation is irreversible.

1.4 Determination of Compressive Strength:

[0110] Compressive strength is determined in accordance with DIN 53421/DIN EN ISO 604.

1.5 Determination of Dimensional Stability Autoclave):

[0111] 1 day after production of a foam block, 18 samples uniformly distributed over the entire length of said block are taken. The approximate dimensions of the test samples are 554 cm.sup.3. Precise volume is determined via immersion in a water bath. The samples are then dabbed dry and placed for 10 minutes in an autoclave at a gage pressure of 0.7 bar. The volume of each test sample is again determined, and the average value is calculated from all of the relative volume decreases.

1.6 Shelf Life Tests:

[0112] The polyol components are stored for 6 months at room temperature and/or 45 C. Foam samples were produced directly after blending of polyol component, and adhesion was determined at 35 C. or 30 C. mold temperature. After six months, foam samples were again produced and tested.

2. Starting Materials

[0113] Polyol 1: Polyether alcohol based on sorbitol and propylene oxide with OH number 490 mg KOH/g, viscosity 23 000 mPas at 25 C. and functionality 5.

[0114] Polyol 2: Polyether alcohol based on trimethylolpropane and propylene oxide with OH number 160 mg KOH/g, viscosity 300 mPas at 25 C. and functionality 3.

[0115] Polyol 3: Polyether alcohol based on glycerol, ethylene oxide and propylene oxide with OH number 160 mg KOH/g, viscosity 250 mPas at 25 C. and functionality 3.

[0116] Polyol 4: Polyether alcohol based on glycerol and propylene oxide with OH number 400 mg KOH/g, viscosity 400 mPas at 25 C. and functionality 3.

[0117] Polyol 5: Castor oil with OH number about 160 mg KOH/g, viscosity 1000 mPas at 20 C. and functionality 2.5.

[0118] Polyol 6: Polyester alcohol based on phthalic anhydride, oleic acid, diethylene glycol and monoethylene glycol with OH number 210 mg KOH/g, viscosity 2750 mPas at 25 C. and functionality 1.75.

[0119] Polyol 7: Polyester alcohol based on phthalic anhydride, oleic acid, diethylene glycol and on a polyether alcohol based on trimethylolpropane and ethylene oxide with OH number 610 mg KOH/g, viscosity 640 mPas at 25 C. and functionality 3.0. The OH number of the polyester alcohol is 250 mg KOH/g, its viscosity 1250 mPas at 25 C., and its functionality 2.22.

[0120] Polyol 8: Polyethylene glycol with an OH number of 188 mg KOH/g, viscosity 46 mPas at 50 C. and functionality 2.

[0121] Polyol 9: Polyester alcohol based on phthalic acid, diethylene glycol and monoethylene glycol with OH number 240 mg KOH/g, viscosity 7500 mPas at 25 C. and functionality 2.

[0122] Flame retardant: Tris(2-chloroisopropyl) phosphate with 9.5% phosphorus content and viscosity 71 mPas at 25 C.

[0123] Stabilizer 1: Tegostab B 8467 (Evonik)

[0124] Stabilizer 2: Niax Silicone L 6900 (Momentive Performance Materials)

[0125] Amine catalyst 1: Dimethylcyclohexylamine

[0126] Amine catalyst 2: Lupragen N 600 (BASF SE)

[0127] Blowing agent: formic acid, 85%

[0128] Catalyst 1: potassium formate, 40%/monoethylene glycol

[0129] Catalyst 2: bis(2-dimethylaminoethyl) ether, 20%/dipropylene glycol

[0130] Catalyst 3: N-methylbis-2-dimethylaminoethylamine, 26%/polyethylene glycol with OH number 250 mg KOH/g

[0131] Isocyanate 1: Lupranat M20 from BASF SE, polymeric MDI with 31.8% NCO content and viscosity 210 mPas at 25 C.

[0132] Isocyanate 2: Lupranat M50 der BASF SE, polymeric MDI with 31.5% NCO content and viscosity 550 mPas at 25 C.

3. General Descriptions of Experiments

3.1 General Production Protocol (Manually Foamed Specimens)

[0133] The polyol components are thoroughly mixed with the stated quantity of isocyanate component by a laboratory stirrer (Vollrath stirrer) at a stirring rate of 1400 revolutions per minute and with a stirring time of 10 seconds, in a beaker, in which the mixture was also foamed. The variable determined in this beaker test are cream time, fiber time and full rise time, envelope density, and also when necessary brittleness.

3.2 General Description of Experiments (Machine Experiments)

[0134] A polyol component is produced from the stated raw materials. The polyol component is mixed with the respectively stated quantity of the stated isocyanate by means of a PU 30/80 IQ high-pressure Puromat (Elastogran GmbH) with an output rate of 250 g/s. The reaction mixture is introduced into temperature-controlled molds measuring

200020055 mm.sup.3 (lance)

[0135] and allowed to foam therein. The mold is lined in advance with paper coated on one side with aluminum. The foam is applied to the aluminum-coated surface, and the mold is then closed.

[0136] Unless otherwise stated, the mold is controlled to a temperature of 45 C. and the foam is demolded after a defined time. Unless otherwise stated, overpacking is 14.5%. The coated paper is removed prior to all of the following measurements with the exception of measurement of adhesion.

(a) Determination of Cream Time and Fiber Time, and Also Free Core Envelope Density:

[0137] About 1000 g of the reaction mixture are injected in a PE bag (diameter about 30 cm). Cream time is defined as the period between start of injection and start of volume expansion of the reaction mixture. Fiber time is the period between start of injection and the juncture at which it becomes possible to draw fibers from the reaction mixture by using a foam strip. After hardening of the foam (24 h later), five samples measuring about 606060 mm.sup.3 are cut from the center of the same sample in order to determine the free-foamed envelope density of the core. They are weighed, and their volume is determined via emersion in a water bath. The free envelope density of the core is calculated from these variables, and the average value is reported.

(b) Determination of Minimal Fill Density:

[0138] Minimal fill density is defined as the envelope density that is just sufficient to fill the lance mold. This is measured by producing, in the lance mold, a foam which fills from 90% to 95% of the mold and extrapolating to 100% fill. The quotient calculated from minimal fill density and free envelope density of the core is termed flow factor.

4. Examples

4.1 The polyol components listed in tables 1a and 1b were reacted with isocyanate 1 in accordance with the general production protocol under 3.1 (isocyanate index 118).

[0139] Table 2a collates the properties of the resultant rigid foams. The demolding time for determination of adhesion was 7 minutes. Adhesion was measured after a further 3 minutes, i.e. after a total of 10 minutes.

TABLE-US-00001 TABLE 1a Composition of polyol component Example Compound 1 (C) 2 3 4 5 6 Polyol 1 36.900 36.900 36.900 36.900 36.900 36.900 Polyol 2 36.050 36.050 36.050 36.050 36.050 36.050 Polyol 4 3.000 3.000 3.000 3.000 3.000 3.000 N,N-Dimethyl- 2.500 2.500 2.500 2.500 2.500 2.500 benzylamine Propylene 2.000 2.000 carbonate Stabilizer 2 2.000 2.000 2.000 2.000 2.000 2.000 Polyol 5 12.000 12.000 12.000 12.000 12.000 12.000 Amine cat 2 0.400 0.400 0.400 0.400 0.400 0.400 Amine cat 1 0.800 0.800 0.800 0.800 0.800 0.800 Water 4.350 4.350 4.350 4.350 4.350 4.350 Ethyl 2.000 acetoacetate Diethyl 2.000 malonate Isopropyl 2.000 myristate Methyl 2.000 acetoacetate Ethyl 2.000 cinnamate

TABLE-US-00002 TABLE 1b Composition of polyol component Example Compound 7 8 9 10 11 Polyol 1 36.900 36.900 36.900 36.900 36.900 Polyol 2 36.050 36.050 36.050 36.050 36.050 Polyol 4 3.000 3.000 3.000 3.000 3.000 N,N- 2.500 2.500 2.500 2.500 2.500 Dimethylbenzylamine Propylene carbonate Stabilizer 2 2.000 2.000 2.000 2.000 2.000 Polyol 5 12.000 12.000 12.000 12.000 12.000 Amine cat 2 0.400 0.400 0.400 0.400 0.400 Amine cat 1 0.800 0.800 0.800 0.800 0.800 Water 4.350 4.350 4.350 4.350 4.350 Diethylene glycol 2.000 Monoethylene glycol 2.000 Oleic acid 2.000 Decanol 2.000 Octanol 2.000

TABLE-US-00003 TABLE 2a Adhesion, Homogeneity after Example 35 C. [N] 90 days 1 9.58 satisfactory 2 10.22 satisfactory 3 7.73 satisfactory 4 6.86 satisfactory 5 6.43 satisfactory 6 7.94 satisfactory 7 10.10 satisfactory 8 4.48 satisfactory 9 6.55 satisfactory 10 3.39 satisfactory 11 5.13 satisfactory

[0140] Shelf life was tested for examples 1, 2, 3, 6 and 7. Table 2b collates the results. Demolding time for determination of adhesion was 7 minutes in every case. Adhesion was measured after a further 3 minutes, i.e. after a total of 10 minutes.

TABLE-US-00004 TABLE 2b Example 1 (C) 2 3 6 7 Adhesion, 35 C., [N] 9.6 10.2 7.7 7.9 10.1 Adhesion, 30 C., [N] 6.6 0.5 0.5 Adhesion, 25 C., [N] 0.9 Adhesion, 35 C., after storage 9.8 10.9 11.3 11.8 1.7 for 6 months at RT [N] Adhesion, 35 C., after storage 5.4 1.7 11.3 10.3 2.1 for 6 months at 45 C. [N] Adhesion, 30 C., after storage 2.2 1.1 3.7 for 6 months at RT [N] Adhesion, 30 C., after storage 1.3 1.9 2.6 0.9 for 6 months at 45 C. [N] Adhesion, 25 C., after storage 1.0 for 6 months at RT [N] Adhesion, 25 C., after storage 1.5 for 6 months at 45 C. [N]
4.2 In the machine experiment, the polyol components listed in table 3 were reacted with isocyanate 1 in accordance with the general experimental description (isocyanate index 118, overpacking 14.5%).

[0141] Table 4 collates the properties of the resultant rigid foams. Demolding time for determination of adhesion was 7 minutes in every case. Adhesion was measured after a further 3 minutes, i.e. after a total of 10 minutes.

TABLE-US-00005 TABLE 3 Composition of polyol component Example Compound 12 (C) 13 14 Polyol 1 36.900 36.900 36.900 Polyol 2 36.050 36.050 36.050 Polyol 4 3.000 3.000 3.000 N,N-Dimethylbenzylamine 2.500 2.500 2.500 Propylene carbonate 2.000 Stabilizer 2 2.000 2.000 2.000 Polyol 5 12.000 12.000 12.000 Amine cat 2 0.400 0.400 0.400 Amine cat 1 0.800 0.800 0.800 Water 4.350 4.350 4.350 Diethyl malonate 2.000 Ethyl cinnamate 2.000

TABLE-US-00006 TABLE 4 Machine experiment Example 12 (C) 13 14 Cream time [s] 8 8 8 Gel time [s] 45 49 44 Free-foamed envelope density [g/l] 24.9 24.4 24.0 Overall envelope density [g/l] 33.9 32.5 32.3 Flow factor 1.36 1.33 1.35 Adhesion [N] 30 C. 1.85 1.12 1.18 35 C. 7.87 6.27 6.07 40 C. 10.74 8.45 7.69 45 C. 12.18 10.63 8.30 Compressive strength [N/mm.sup.2] 0.183 0.177 0.153 Dimensional stability [vol %] 1.01 0.58 1.50
4.3 In the machine experiment, the polyol components listed in table 5 were reacted with isocyanate 1 (isocyanate index 114, overpacking 14.5%).

[0142] Table 6 collates the properties of the resultant rigid foams.

TABLE-US-00007 TABLE 5 Composition of polyol component Compound Example 15 Polyol 1 36.200 Polyol 3 35.850 Polyol 4 3.000 N,N-Dimethylbenzylamine 1.500 Stabilizer 2 3.000 Polyol 5 12.000 Amine cat 2 0.250 Amine cat 1 0.400 Water 4.800 Diethyl malonate 3.000

TABLE-US-00008 TABLE 6 Machine experiment Example 15 Cream time [s] 16 Gel time [s] 80 Free-foamed envelope density [g/l] 25.4 Overall envelope density [g/l] 39.04 Compressive strength [N/mm.sup.2] 0.168 Dimensional stability [vol %] 0.73
4.4 In accordance with the general production protocol under 3.1, the polyol components listed in table 7 were reacted with isocyanate 2.

[0143] Table 8 collates the properties of the resultant rigid foams. Demolding time for determination of adhesion was 21 minutes in every case. Adhesion was measured after a further 3 minutes, i.e. after a total of 24 minutes.

TABLE-US-00009 TABLE 7 Composition of polyol component Example Compound 16 (C) 17 18 (C) 19 Polyol 6 48.400 48.400 Flame retardant 25.000 25.000 12.000 12.000 Polyol 7 15.000 15.000 Polyol 8 8.000 8.000 8.000 8.000 Stabilizer 1 2.000 2.000 2.000 2.000 Formic acid, 85% 1.600 1.600 1.200 1.200 Diethyl malonate 1.000 3.000 Polyol 9 76.400 76.400 Catalyst 1 1.400 1.400 1.200 1.200 Catalyst 2 2.400 2.400 Catalyst 3 3.300 3.300 80/20 mixture of n-pentane 8.000 8.000 13.500 13.500 and isopentane Index 289 292 333 341

TABLE-US-00010 TABLE 8 Example 16 (C) 17 18 (C) 19 Cream time [s] 14 14 12 13 Fiber time [s] 51 59 48 58 Full rise time [s] 76 78 78 80 Adhesion, 35 C., 21/24 min 2.22 2.73 6.21 13.32

[0144] 4.5 In accordance with the general production protocol under 3.1, the polyol components listed in table 9 were reacted with isocyanate 1.

[0145] Table 10 collates the properties of the resultant rigid foams. Demolding time for determination of adhesion was 7 minutes. Adhesion was measured after a further 3 minutes, i.e. after a total of 10 minutes.

TABLE-US-00011 TABLE 9 Composition of polyol component Example Compound 20 21 22 23 24 25 26 27 Polyol 1 35.800 35.800 35.800 35.800 35.800 35.800 35.800 35.800 Polyol 3 35.500 38.500 37.500 33.500 30.500 35.500 35.500 35.500 Polyol 4 3.000 3.000 3.000 3.000 3.000 3.000 3.000 3.000 N,N-Dimethyl- 1.500 1.500 1.500 1.500 1.500 1.500 1.500 1.500 benzylamine Stabilizer 2 3.000 3.000 3.000 3.000 3.000 3.000 3.000 3.000 Polyol 5 12.000 12.000 12.000 12.000 12.000 12.000 12.000 12.000 Amine cat 2 0.500 0.500 0.500 0.500 0.500 0.500 0.500 0.500 Amine cat 1 0.900 0.900 0.900 0.900 0.900 0.900 0.900 0.900 Water 4.800 4.800 4.800 4.800 4.800 4.800 4.800 4.800 Diethyl malonate 3.000 1.000 5.000 8.000 Malonic acid 3.000 Acetylacetone 3.000 Fe(III) 3.000 acetylacetonate Index 115 114 114 115 116 115 115 114

TABLE-US-00012 TABLE 10 Example 20 21 22 23 24 25 26 27 Cream time [s] 15 15 15 15 14 21 16 14 Fiber time [s] 63 62 61 63 64 120 73 43 Full rise time [s] 98 95 96 98 103 170 108 64 Envelope 28.4 28.3 28.4 27.9 28.0 27.1 28.2 28.5 density [g/l] Adhesion [N], 9.26 5.76 5.52 9.42 9.62 0.51 1.39 35 C., 7/10 min Phase-stability homo- homo- homo- homo- homo- precipitate homo- precipitate of polyol geneous geneous geneous geneous geneous geneous component (homogeneity)

5. Shrinkage Behavior (Dimensional Stability at Room Temperature (20 C.) Over a Defined Time)

[0146] The shrinkage test for a foam consists in a purely visual assessment. The foamed samples are compared with a comparative system (sample S-1, corresponding to the original). All of the samples, including the comparative sample S-1, are produced on the same day in order to ensure comparability. The samples are examined visually every 2-3 days over a period of 4 weeks. Shrinkage of the sample is recorded as more than, less than, or the same as that of the original, or no shrinkage at all.

TABLE-US-00013 TABLE 11 Tests relating to shrinkage behavior Example S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 Polyol 1 36.20 Polyol 3 35.85 Polyol 4 3.000 N,N-Dimethyl- 1.500 benzylamine Stabilizer 2 3.000 Polyol 5 12.00 Amine cat 2 0.250 Amine cat 1 0.400 Water 4.800 Diethyl malonate % 3.0 Dimethyl adipate % 3.0 1.0 0.6 0.7 0.6 Dimethyl glutarate % 3.0 1.0 1.8 2.3 2.0 2.0 Dimethyl succinate % 3.0 1.0 0.6 1.0 0.4 Cream time s 27 28 29 28 28 27 26 28 30 Fiber time s 148 141 143 140 140 137 137 142 145 Envelope density g/l 31.2 31.2 31.3 30.7 30.5 30.4 30.3 30.9 30.9 Adhesion, N 0.60 1.49 0.47 0.80 0.48 0.45 0.48 0.47 0.50 30 C., 7/10 min Shrinkage in = > = > > > = comparison with original Phase-stability of homo homo- homo- homo- homo- homo- homo- homo- homo- polyol component geneous geneous geneous geneous geneous geneous geneous geneous geneous