PUR-/PIR RIGID FOAMS CONTAINING POLYESTER POLYOLS WITH REDUCED FUNCTIONALITY

Abstract

The invention relates to a method for preparing polyester polyols containing monools, and to their use, in particular for preparing polyurethane/polyisocyanurate rigid foams (also referred to hereafter as PUR/PIR rigid foams) with improved fire performance.

Claims

1. A multistage process for producing a polyester polyol PES-B comprising: a) completely reacting at least one carboxyl compound selected from the group consisting of i) polyfunctional carboxylic acids and ii) polyfunctional hydroxy-reactive carboxylic acid derivatives selected from the group consisting of carbonyl chlorides, alkyl carboxylates, hydroxy-functional carboxylic acids, lactones and carboxylic anhydrides with at least one polyol containing 2-8 hydroxy groups to afford a polyester polyol PES-A, wherein in step a) the ratio of the molar amount of employed hydroxyl groups [n(OH).sub.a] to the molar amount of carboxyl-equivalent groups [n(carboxy).sub.a] is:
n(OH).sub.a/n(carboxy).sub.a>1, and b) subsequently reacting the polyester polyol PES-A obtained in step a) with a monofunctional alcohol to afford the PES-B, wherein the ratio of the molar sum of the hydroxy groups n(OH).sub.reactant of all reactant molecules employed in steps a) and b) to the molar sum of the employed carboxyl-equivalent groups n(carboxy).sub.reactant is:
n(OH).sub.reactant/n(Carboxy).sub.reactant>1.

2. The process as claimed in claim 1, wherein the polyester polyol PES-B has a number-average OH functionality of >1.00 to <2.00.

3. The process as claimed in claim 1, wherein the carboxyl compound in step a) comprises glutaric acid, succinic acid, adipic acid, terephthalic acid, phthalic acid, isophthalic acid, a derivative of any thereof, or a combinations of any thereof.

4. The process as claimed in claim 1, wherein the at least one polyol in step a) comprises a polyol containing 2-3 hydroxy groups.

5. The process as claimed in claim 4, wherein the at least one polyol in step a) comprises a polyol containing 2 hydroxy groups.

6. The process as claimed in claim 1, wherein the monofunctional alcohol comprises 1-octanol, 2-octanol, 3-octanol, 4-octanol, 2-ethyl-1-hexanol, cis-2-hexen-1-ol, citronellol, 1-decanol, 1-dodecanol, 1-tetradecanol, 1-hexadecanol, 1-octadecanol, 1-tetracosanol, benzyl alcohol, or a combination thereof.

7. The process as claimed in claim 1, wherein the monofunctional alcohol comprises a reaction product of a monofunctional alcohol with an alkylene oxide.

8. A polyester polyol obtained by the method as claimed in claim 1.

9. The polyester polyol as claimed in claim 8 having a hydroxyl number of 150 to 300 mg KOH/g, and a number-average functionality of 1.00 to <2.00.

10. A rigid PUR/PIR foam containing the polyester polyol as claimed in claim 8.

11. A reaction system for producing a rigid PUR and PIR foam comprising: A) an organic polyisocyanate component; B) a polyol component C) optionally auxiliary and additive substances, blowing agents and co-blowing agents, wherein the organic polyisocyanate component A) is employed in such a quantity ratio to the components B) and optionally C) that an index of 100 to 500 results, and the reaction system is characterized in that the polyol component B) comprises at least one polyester polyol as claimed in claim 9.

12. A process for producing a rigid PUR and PIR foam, comprising mixing and reacting the reaction system as claim in claim 11.

13. A rigid PUR/PIR foam obtained by mixing and reacting the components A) and B) and optionally C) of the reaction system as claimed in claim 11.

14. The rigid foam as claimed in claim 13, wherein the rigid foam has a density of 25 to 65 kg/m.sup.3 and is in the form of an insulation sheet or in the form of a composite element having flexible or inflexible outer layers or wherein the rigid foam is in the form of a block foam having a density of 25 to 300 kg/m.sup.3.

15. The process as claimed in claim 7, wherein the alkylene oxide comprises ethylene oxide and the monofunctional alcohol comprises 1-hexanol, 1-butanol, 1-propanol, 1-octanol, 2-octanol, 3-octanol, 4-octanol, 2-ethyl-1-hexanol, cis-2-hexen-1-ol, citronellol, 1-decanol, 1-dodecanol, 1-tetradecanol, 1-hexadecanol, 1-octadecanol, 1-tetracosanol, benzyl alcohol, or a combination of any thereof.

Description

EXAMPLES

[0068] The experiments marked with an * denote comparative examples.

[0069] Raw Materials and Methods: [0070] TCPP trischloroisopropyl phosphate (Levagard PP®, Lanxess AG), flame retardant [0071] TEP Levagard® TEP, Lanxess AG, flame retardant, triethyl phosphate [0072] Cat-1 Desmorapid® DB, Covestro Deutschland AG, is an activator for the production of rigid polyurethane (PUR) foams based on a tertiary amine [0073] B 8443 TEGOSTAB® B 8443 from Evonik is a non-hydrolyzable polyether-polydimethylsiloxane copolymer [0074] Cat-2 Desmorapid® 1792, Covestro Deutschland AG. [0075] Preparation containing diethylene glycol and potassium acetate. [0076] Trimerization catalyst. [0077] B-1 polyether polyol based on ortho-toluenediamine, ethylene oxide and propylene oxide having an OH number of 415 mg KOH/g from Covestro Deutschland AG, viscosity at 25° C. about 8000 mPas. [0078] B-2 polyester polyol composed of phthalic anhydride and diethylene glycol, OH number 795 mg KOH/g, from Covestro Deutschland AG, viscosity 160 mPas at 25° C., acidity 97 mg KOH/g. [0079] PES-B1* bifunctional polyester polyol composed of technical grade glutaric acid and ethylene glycol from Covestro Deutschland AG for production of rigid PUR/PIR foams having a hydroxyl number of about 240 mg KOH/g, an acid number of about 1.75 mg KOH/g and a viscosity at 20° C. of 15590 mPa.Math.s. [0080] A-1 Desmodur®44V70L, polymeric MDI from Covestro Deutschland AG having an NCO content of 30.5% to 32% by weight [0081] Glutaric acid, techn. Lanxess AG [0082] Benzoic acid Acros [0083] 1-Decanol abcr GmbH [0084] Ethylene glycol INEOS AG [0085] n-Pentane Kraemer & Martin GmbH

[0086] The analyses were conducted as follows:

[0087] Dynamic viscosity: MCR 51 Rheometer from Anton Paar in accordance with DIN 53019 with a CP 50-1 cone, diameter 50 mm, angle 1° at shear rates of 25, 100, 200 and 500 The inventive and non-inventive polyester polyols exhibit viscosity values that are independent of the shear rate. Hydroxyl number: in accordance with the standard DIN 53240 (December 1971)

[0088] Acid number: in accordance with the standard DIN EN ISO 2114 (June 2002)

[0089] Mechanical properties were determined by means of a tensile test according to EN1607 (DIN EN 14509), May 2013 version, wherein the force was applied perpendicularly to the outer layer, i.e. in the foaming direction. These measurements give the parameter elastic modulus (also known as Young's modulus).

[0090] Also performed was a compression test in the foaming direction according to DIN EN 826 (May 2013 version) which likewise gave the parameter elastic modulus (also known as Young's modulus).

[0091] Also performed was a compression test perpendicular to the foaming direction according to DIN EN 826 (May 2013 version) which likewise gave the parameter elastic modulus (also known as Young's modulus).

[0092] Fire properties were determined according to DIN 4102-1 (May 1998 version), wherein the maximum flame height and the destroyed specimen length are in each case determined as measured values for five individual specimens. [0093] Apparent density: determined according to DIN EN ISO 845 (October 2009 version). [0094] Open-cell content according to DIN EN ISO 4590 (June 2014 version) [0095] Cream time: The period elapsing from the start of mixing of the main components to visible commencement of foaming of the mixture. [0096] Fiber time: The fiber time (“gel point t.sub.G”) is determined by dipping a wooden rod into the reacting mixture and withdrawing it again. It characterizes the time from which the mixture begins to harden. Reported as t.sub.G is the time at which it first becomes possible to draw fibers between the wooden stick and the reacting mixture. The time measurement starts with the mixing of the foam components. [0097] Tack-free time: Shortly after the fiber time has been reached, a wooden stick is used at short time intervals to test the foam surface. The tack-free time, measured from the start of the mixing procedure, is reached when the wooden stick is released from the foam surface without difficulty and without any adhering product.

[0098] Functionality is calculated by reference to the functionality of the employed reactants.

[0099] 1. Production of the Polyester Polyols

Polyester Polyol PES-B2*

[0100] A 4 liter four-neck flask fitted with a mechanical stirrer, 50 cm random-packed column, thermometer, nitrogen inlet and also a column head, distillation bridge and vacuum membrane pump was initially charged with 1797 g (13.41 mol, 56.15% by weight) of technical grade glutaric acid, 188 g (1.54 mol, 5.88% by weight) of benzoic acid and 1215 g (19.57 mol, 37.97% by weight) of ethylene glycol and this initial charge was heated to 200° C. under a nitrogen blanket over the course of 60 min to distill off water of reaction; this distillate was monophasic and had a pH of 7. After 5 hours the pressure was slowly reduced to 200 mbar over the course of 3 hours. The mixture was reacted under these conditions for 40 hours and the OHN and the acid number were found to be 176 mg KOH/g and 1.1 mg KOH/g respectively. Discharged ethylene glycol (57.6 g) was replenished and stirred in at 160° C. at atmospheric pressure for a further 6 hours.

[0101] Analysis of the Polyester PES-B2*: [0102] Hydroxyl number: 209.8 mg KOH/g [0103] Acid number: 0.9 mg KOH/g [0104] Viscosity: 1000 mPas (25° C.) [0105] Functionality: 1.75

Polyester Polyol PES-B3*

[0106] a) A 4 liter four-neck flask fitted with a mechanical stirrer, 50 cm random-packed column, thermometer, nitrogen inlet and also a column head, distillation bridge and vacuum membrane pump was initially charged with 1661 g (12.40 mol, 51.91% by weight) of technical grade glutaric acid, 381 g (3.13 mol, 11.93% by weight) of benzoic acid and 1157 g (18.65 mol, 36.20% by weight) of ethylene glycol and this initial charge was heated to 200° C. under a nitrogen blanket over the course of 60 min to distil off water of reaction. After 5 hours the pressure was slowly reduced to 200 mbar over the course of 3 hours. The mixture was reacted under these conditions for 40 hours; the distillates were monophasic and had a pH of 7. The OHN and the acid number were found to be 154.4 mg KOH/g and 1.4 mg KOH/g respectively. Discharged ethylene glycol (42.4 g, 0.68 mol) was replenished and stirred in at 200° C. at atmospheric pressure for a further 6 hours.

[0107] Analysis of the Polyester B-3*: [0108] Hydroxyl number: 179.2 mg KOH/g [0109] Acid number: 1.23 mg KOH/g [0110] Viscosity: 1010 mPas (25° C.) [0111] Functionality: 1.50

Polyester Polyol PES-B4

[0112] a) A 4 liter four-neck flask fitted with a mechanical stirrer, 50 cm random-packed column, thermometer, nitrogen inlet and also a column head, distillation bridge and vacuum membrane pump was initially charged with 1680 g (12.54 mol) of technical grade glutaric acid and 1045 g (16.83 mol) of ethylene glycol and this initial charge was heated to 200° C. under a nitrogen blanket over the course of 60 min to distill off water of reaction. After 3 hours the pressure was slowly reduced to 30 mbar over the course of 3 hours. The mixture was reacted under these conditions for 24 hours. The OHN and the acid number were found to be 159.8 mg KOH/g and 0.5 mg KOH/g respectively. Discharged ethylene glycol (74 g, 1.19 mol) was replenished and stirred in at 200° C. at atmospheric pressure for a further 6 hours. The OHN and the acid number were found to be 210.2 mg KOH/g and 0.47 mg KOH/g respectively. [0113] b) 227 g (1.43 mol) of 1-decanol was subsequently added and the mixture was stirred at 200° C. at atmospheric pressure for 6 hours.

[0114] Analysis of the Polyester PES-B4: [0115] Hydroxyl number: 219.9 mg KOH/g [0116] Acid number: 0.5 mg KOH/g [0117] Viscosity: 580 mPas (25° C.) [0118] Functionality: 1.75

Polyester Polyol PES-B5*, Comparative Example

[0119] A 4 liter four-neck flask fitted with a mechanical stirrer, 50 cm random-packed column, thermometer, nitrogen inlet and also a column head, distillation bridge and vacuum membrane pump was initially charged with 1367 g (10.21 mol) of technical grade glutaric acid, 826 g (13.30 mol) of ethylene glycol and 490 g (3.1 mol) of 1-decanol and this initial charge was heated to 200° C. under a nitrogen blanket over the course of 60 min to distill off water of reaction which was cloudy and subsequently separated into two phases. After 3 hours the pressure was slowly reduced to 250 mbar over the course of 2 hours. The mixture was reacted under these conditions for 15 hours and further water of reaction forming two phases was separated. The OHN and the acid number were found to be 145.9 mg KOH/g and 1.3 mg KOH/g respectively.

[0120] The biphasic nature of the water of reaction indicates that it contains proportions of 1-decanol; it is known from the examples A-4, PES-B3 and PES-B2 that ethylene glycol is also discharged under these conditions. 1-Decanol is known to be only slightly soluble in water (about 40 mg/1). However, since the water phase also contains ethylene glycol certain proportions of 1-decanol are presumably dissolved in the ethylene glycol-containing water phase just as certain proportions of ethylene glycol are present in the 1-decanol phase. Since adjustment of the functionality of the polyester polyol absolutely requires precise knowledge of the distillatively removed amounts and correspondingly replenishable amounts of ethylene glycol and 1-decanol but these are only experimentally determinable at great complexity, the batch had to be disposed of A monool cannot reproducibly be reacted with diol in a single-step esterification in this way.

Polyester Polyol PES-B6*, Comparative Example

[0121] A 4 liter four-neck flask fitted with a mechanical stirrer, 50 cm random-packed column, thermometer, nitrogen inlet and also a column head, distillation bridge and vacuum membrane pump was initially charged with 1124.5 g (8.39 mol) of technical grade glutaric acid, 279.8 g (0.99 mol) of oleic acid and 1445.2 g (13.6 mol) of diethylene glycol and this initial charge was heated to 200° C. under a nitrogen blanket over the course of 60 min to distill off water of reaction. After 4 hours the pressure was slowly reduced to 100 mbar over the course of 3 hours. The mixture was reacted under these conditions for 24 hours. The OHN and the acid number were found to be 180 mg KOH/g and 0.7 mg KOH/g respectively. Discharged diethylene glycol (58 g, 0.55 mol) was replenished and stirred in at 200° C. at atmospheric pressure for a further 5 hours.

[0122] Analysis of the polyester PES-B6*: [0123] Hydroxyl number: 199.4 mg KOH/g [0124] Acid number: 0.9 mg KOH/g [0125] Viscosity: 540 mPas (25° C.)

TABLE-US-00001 TABLE 1 Formulations and properties of inventive and noninventive polyester polyols PES-B Example: PES-B2* PES B3* PES-B4 PES-B6* Formulation: Glutaric acid [% by wt.] 56.15 51.91 56.91 39.5 Benzoic acid [% by wt.] 5.88 11.93 Ethylene glycol [% by wt.] 37.97 36.17 35.4 Diethylene glycol [% by wt.] 50.7 1-Decanol [% by wt.] 7.69 Oleic acid [% by wt.] 9.8 Properties: OH number [mg KOH/g] 209.8 179.2 219.9 199.4 Acid number [mg KOH/g] 0.88 1.23 0.5 0.9 Functionality, 1.75 1.5 1.75 1.8 calculated Viscosity 25° C. [mPa*s] 1000 1010 580 540

[0126] 2. Production of the Rigid PUR/PIR Foams:

[0127] Rigid PUR/PIR foams were produced on the basis of the above-described polyester polyols PES-B. To this end the respective polyester polyol PES-B according to table 2 was initially charged with the further polyols B-1 and B-2 and admixed with the flame retardant, a foam stabilizer based on polyether siloxane, catalysts and n-pentane as blowing agent, the mixture thus obtained was mixed with polyisocyanate A-1 and the mixture was poured into a wooden box mould open at the top (30×30×10 cm.sup.3) and allowed to fully react therein. The formulations and results of the physical measurements on the specimens obtained are shown in table 2.

TABLE-US-00002 TABLE 2 Production and properties of inventive and noninventive (comparative, *) rigid PUR/PIR foams Example B-1* B-2* B-3* B-4 B-6* Polvol component: PES-B1* [pts. by wt.] 66.50 PES-B2* [pts. by wt.] 66.50 PES-B3* [pts. by wt.] 66.50 PES-B4 [pts. by wt.] 66.50 PES-B6* [pts. by wt.] 66.50 TCPP [pts. by wt.] 20.80 20.80 20.80 20.80 20.80 TEP [pts. by wt.] 5.20 5.20 5.20 5.20 5.20 B-1 [pts. by wt.] 5.20 5.20 5.20 5.20 5.20 B-2 [pts. by wt.] 2.30 2.30 2.30 2.30 2.30 B8443 [pts. by wt.] 3.50 3.50 3.50 3.50 3.50 Cat-1 [pts. by wt.] 1.50 1.50 1.50 1.50 1.50 Cat-2 [pts. by wt.] 3.70 3.70 3.70 3.70 3.40 n-Pentane [pts. by wt.] 16.50 15.50 14.60 15.50 16.70 Isocvanate-side formulation: A-1 [pts. by wt.] 169.90 155.40 140.90 160.30 148.80 Index 300 300 300 300 300 Processing: Cream time [s] 13 13 12 13 11 Fiber time [s] 44 39 39 35 35 Tack-free time [s] 60 56 60 50 55 Properties: Apparent density [kg/m.sup.3] 34.00 33.70 35.10 34.10 35.46 Elastic modulus, [N/mm.sup.2] 13.23 11.16 12.24 12.67 11.79 tensile test perpendicular to outer layer Elastic modulus, [MPa] 9.76 8.31 8.10 7.79 7.40 compression test in foaming direction Elastic modulus, [MPa] 2.82 2.12 1.79 2.03 1.71 compression test perpendicular to foaming direction Fire safety class not met met met met met B2 Open-cell content [%] 7.70 11.10 9.00 11.10 not determined

[0128] Table 2 shows that in terms of fire safety the rigid PUR-PIR foams based on the inventive polyols PES-B4 are markedly superior to the rigid PUR-PIR foam based on the noninventive polyol PES-B 1 and equivalent to the polyols PES-B2 and PES-B3. The substantial difference between the polyol PES-B4 and the noninventive polyol PES-B1 is merely the functionality of the employed polyester polyol. All other formulation constituents are identical in their usage amounts apart from the isocyanate amount, different isocyanate amounts being necessary to likewise keep the indices of all formulations identical at 300. The apparent densities of all foams are likewise within a very narrow window. In terms of processing characteristics, just as few large differences as for the mechanical properties are determinable. Closed-celled, fine-celled, dimensionally stable foams were obtained in all cases. PES-B4 is a good alternative to the known polyester polyols PES-B2 and PES-B3. The process according to the invention allows reproducible production of the polyester polyol PES-B4 and makes it possible to use monools for production of polyester polyols.