POLYURETHANE-BASED INSULATION BODY AND METHOD FOR PRODUCING SAME

Abstract

The present invention relates to an insulation body based a hard, fine-cell and open-cell polyurethane/polyisocyanurate foam with a barrier film, and a method for producing same.

Claims

1. A process for producing an insulation body based on a fine- and open-celled polyurethane/polyisocyanurate foam in a cavity of a mold, comprising: a. optionally inserting an optionally pre-molded insert into the cavity of the mold, b. inserting a barrier film into the cavity or, if present, onto or into the insert, c. applying a pressure of 8-30 bar in the cavity, d. injecting a polyurethane reactive mixture containing supercritical CO.sub.2 into the pressurized cavity, e. decompressing to ambient pressure after a time of 1 to 40 seconds measured after the injection, f. curing the polyurethane reactive mixture, g. applying a vacuum of 0.001 mbar to 0.5 mbar in the cavity, h. sealing any holes in the barrier film, and i. demolding the resulting insulation body.

2. The process for producing an insulation body according to claim 1, wherein a gas scavenger material is introduced between step b) and c) and/or between step f) and g).

3. The process for producing an insulation body as claimed in claim 1, wherein the polyurethane reactive mixture comprises: A) isocyanate-reactive component comprising: A1) at least one polyol component having a functionality f of >2.5 selected from the group consisting of polyether polyols, polyester polyols, polycarbonate polyols, polyether polycarbonate polyols and polyether ester polyols, wherein the proportion of all primary OH functions present in the component A1) based on the total number of terminal OH functions in the component A1) is at least 30%, A2) at least one catalyst component having Zerewitinoff-active hydrogens, A3) at least one cell-opening compound, A4) supercritical CO.sub.2, A5) optionally blowing agents with the exception of supercritical CO.sub.2, and A6) optionally auxiliary and/or additive substances and B) at least one polyisocyanate component, wherein, relative to component A), component B) is present in an amount such that a ratio of the number of moles of NCO groups from component B) to the number of moles of OH groups from component A1) is 80 to 400.

Description

EXAMPLES

[0098] Employed Standards/Analytical Instruments:

[0099] Determination of apparent density: Foams composed of rubber and plastics—determination of apparent density (ISO 845:2006); German version EN ISO 845:2009

[0100] Determination of open-cell content: Determination of volume fraction of open and closed cells (ISO 4590:2002); German version EN ISO 4590:2003

[0101] Determination of compressive strength: Rigid foams—determination of pressure properties (ISO 844:2014); German version EN ISO 844:2014

[0102] Determination of OH number: Determination of hydroxyl number—part 2: Method with catalyst according to DIN 53240-2, November 2007 version

[0103] Determination of cell size: Optical microscopy evaluation using a VHX 5000 optical microscope; the test specimen to be analyzed is examined at 3 different points in each case over a circular region having a diameter of 5 mm. The resolution here is chosen such that the selected region captures more than 100 cells. All cells are subsequently evaluated with the freely available software ImageJ and the obtained ECD values (Equivalent Circle Diameter) used to calculate the D90 value (90% of the cells are smaller than this value) and the average cell diameter.

[0104] The indicated functionality fin table 1 relates to the number-average functionality of the mixture of the polyols present in the formulation.

[0105] The indicated duration of foam production in table 1 describes the duration between the juncture of mixing of CO.sub.2 and the polyol formulation and the juncture of demolding/evacuation of the cured PU foam.

[0106] Determination of Thermal Conductivity:

[0107] 1) Thermal Conductivity Value Measurement According to the Dynamic Hot Wire Method:

[0108] A platinum wire (diameter 100 μm) is embedded in the sample and serves simultaneously as a heating element and a temperature sensor. The measurement apparatus is incorporated into a vacuum chamber whose internal pressure is determined by means of a pressure sensor (Baratron®, MKS Instruments Deutschland GmbH, Munich). The required gas pressure is established by controlled charging with gaseous nitrogen via a needle valve.

[0109] During the measurement the wire is heated with a constant electrical power. The profile of the average temperature of the heating wire over time may be captured via the temperature-dependent wire resistance which is in turn measured by simultaneous measurement of the voltage drop over a shunt resistor connected in series with the heating line and of the voltage drop over the potential taps on the heating wire. Two multimeters (type HP3457A, Hewlett-Packard, Palo Alto, USA) were used as voltmeters. This temperature profile depends on the thermal conductivity of the sample. The thermal conductivity of the sample is determined by adapting an analytical solution (siehe Ebert H.-P. et al., High Temp.—High Press., 1993, 25, 391-402) to this time-dependent temperature curve, taking into account the thermal contact resistance between the sample and the wire as well as heat losses in the axial direction. Foam body measuring 50×50×100 mm at 23° C.

[0110] 2) Thermal Conductivity Measurement with a Heat Flow Measuring Plate Instrument According to DIN 52616 (November 1977); Foam Body Measuring 200×200×30 mm at 10° C. and/or 23° C.

[0111] CO.sub.2— and n-pentane-blown polyurethane foams were produced according to the formulations recited in the following table 1. Unless otherwise stated the specified amounts are to be understood as weight fractions. The following substances and materials were used: [0112] Polyol 1: Polyether polyol based on trimethylolpropane and propylene oxide having a hydroxyl number of 800 mg KOH/g, a functionality of 3 and a viscosity of 6100 mPa.Math.s at 25° C. [0113] Polyol 2: Polyether polyol based on trimethylolpropane and ethylene oxide having a hydroxyl number of 550 mg KOH/g, a functionality of 3 and a viscosity of 505 mPa.Math.s at 25° C. [0114] Polyol 3: Polyether polyol based on trimethylolpropane and propylene oxide having a hydroxyl number of 550 mg KOH/g, a functionality of 3 and a viscosity of 1800 mPa.Math.s at 25° C. [0115] Polyol 4: Polyether polyol based on 1,2-propanediol and propylene oxide having a hydroxyl number of 56 mg KOH/g, a functionality of 2 and a viscosity of 310 mPa.Math.s at 25° C. [0116] Polyol 5: Polyether polyol based on 1,2-propanediol and propylene oxide having a hydroxyl number of 112 mg KOH/g, a functionality of 2 and a viscosity of 140 mPa.Math.s at 25° C. [0117] Polyol 6: Polyether polyol based on glycerol and propylene oxide having a hydroxyl number of 231 mg KOH/g, a functionality of 3 and a viscosity of 350 mPa.Math.s at 20° C. [0118] Tegostab B 8443: Foam stabilizer (Evonik) [0119] Ortegol 500: Cell opener (Evonik) [0120] Ortegol 501: Cell opener (Evonik) [0121] Desmorapid PU 1792: Catalyst, 25% potassium acetate in diethylene glycol (Covestro) [0122] Dabco NE1070: Catalyst, 3-(dimethylamino)propylurea (Air Products) [0123] n-Pentane: Blowing agent [0124] Isocyanate: Mixture of monomeric and polymeric MDI having a viscosity of about 290 mPa.Math.s at 20° C. (Desmodur 44V20L, Covestro) [0125] Barrier film: Multilayer film consisting of polyethylene terephthalate, polyethylene and aluminum.

Production of PU-Based Insulation Bodies, Example 1 (Inventive) and 3, 4 and 5 (Comparative)

[0126] A polyol formulation was produced from the polyols, stabilizers and catalysts recited in table 1 hereinbelow in a high-pressure plant. This formulation was mixed with the blowing agent CO.sub.2 with a static mixer at a pressure of 160 bar and a temperature of 50° C. (supercritical conditions). This mixture was mixed with the isocyanate conveyed at a pressure of 160 bar and a temperature of 35° C. in a high-pressure mixing head. The thus obtained reaction mixture was injected into a pressurized cavity of a closed mold at a mold temperature of 50° C. The mold may be provided with a barrier film. After termination of the injection (so-called shot time) the pressure was maintained for a time (so-called cream time) and then decompressed to ambient pressure over <2 s (so-called relaxation time). The precise formulations and plant parameters are summarized in table 1, the results of the physical tests on the insulation bodies, in particular the foams, in table 2.

Production of Molded Polyurethane Foam Bodies, Example 6 (Comparative)

[0127] To produce polyurethane-based molded foam bodies, a polyol formulation was produced from the polyols, stabilizers and catalysts recited in table 1 below and also the blowing agent. To produce the reaction mixture the isocyanate was mixed using a Pendraulik stirrer for 7 seconds at 23° C. and introduced in a mold. The mold was closed immediately. After 5 minutes the mold was opened and the molded body was demolded. The precise formulation is summarized in table 1, the results of the physical tests on the molded foam in table 2.

Example 2 (Comparative)

[0128] All data are taken from patent publication WO2018/018571 A1, example 2, and for comparison inserted into tables 1 and 2.

TABLE-US-00001 TABLE 1 Comparative example 2 WO 2018/018571 Comparative Comparative Comparative Comparative Example 1 A1, Example 2 example 3 example 4 example 5 example 6 Polyol 1 [parts by wt] 13.00 — 13.00 13.00 13.00 13.00 Polyol 2 [parts by wt] 32.50 — 32.50 — — — Polyol 3 [parts by wt] — — — 32.50 32.50 32.50 Polyol 4 [parts by wt] 13.50 — 13.50 13.50 13.50 13.50 Polyol 5 [parts by wt] 9.50 — 9.50 9.50 9.50 9.50 Polyol 6 [parts by wt] 27.00 — 27.00 27.00 27.00 27.00 VORATEC ™ SD301 [parts by wt] — 47.55  — — — — VORANOL ™ CP 260 [parts by wt] — 38.00  — — — — TERCAROL 5903 [parts by wt] — 9.50 — — — — Tegostab B 8443 [parts by wt] 1.50 — 1.50 1.50 1.50 1.50 Ortegol 500 [parts by wt] 0.40 — 0.40 — — — Ortegol 501 [parts by wt] 0.10 — 0.10 — — — L6164 [parts by wt] — 2.00 — — — — Desmorapid PU 1792 [parts by wt] 2.50 — 2.50 2.50 2.50 2.50 DABCO NE1070 [parts by wt] 1.65 — 1.65 1.65 1.65 1.65 POLYCAT ®-5 [parts by wt] — 0.48 — — — — POLYCAT ®-8 [parts by wt] — 1.90 — — — — POLYCAT ®-41 [parts by wt] — 0.57 — — — — Functionality f of polyols 2.9 3.1  2.9 2.9 2.9 2.9 Isocyanate [parts by wt] 97.20 — 97.20 97.20 97.20 97.20 Papi ™-135C — 101.00  — — — — n-Pentane [parts by wt] — — — — — 14.40 Supercritical CO.sub.2 [parts by wt] 3.56 Yes; amount n.s. 3.50 3.57 5.90 — Index NCO/OH 100.00 115.00  100.00 100.00 100.00 100.00 Gas counterpressure in [bar] 7.7 n.a. 8.3 8.2 13.0 — the cavity Shot time [s] 2.0 n.a. 1.7 2.0 1.2 — Cream time [s] 4.0 560.sup.‡    4.3 8.0 9.8 — Relaxation time [s] <2 n.a. <2 <2 <2 — Duration of foam [min] 11 39 + x.sup.† 11 11 11 — production Barrier film yes yes no no no no .sup.‡The cream time in comparative example 2 is the time between the addition of the polyol formulation to the reactor and the injection of the PU mixture into the mold provided with barrier material. The duration of injection is not specified. .sup.†The duration between injecting and evacuating the cured PU foam is not specified. n.s. - not specified

TABLE-US-00002 TABLE 2 Comparative Comparative Comparative Comparative Comparative Example 1 example 2 example 3 example 4 example 5 example 6 Mechanics Apparent density [kg/m.sup.3] 72 115.sup.1)  70 71 45 39 Parallel compressive [MPa] n.d..sup.2) n.s..sup.3) 0.32 n.d..sup.2) n.d..sup.2) 0.16 strength at 10% compression Transverse compressive [MPa] n.d..sup.2) n.s..sup.3) 0.22 n.d..sup.2) n.d..sup.2) 0.11 strength at 10% compression Cell internal pressure [mbar] 0.3 2 1013 1013 1013 1013 Thermal conductivity [mW .Math. m.sup.−1 .Math. K.sup.−1] 9.6 @ 10° C. 13.0 @ 23° C. 34.9@ 23° C..sup.4) 23.8 @ 23° C. 21.9 @ 23° C. 25.3 @ 23° C. 22.7 @ 10° C. 20.5 @ 10° C. 29.1 @ 10° C. Open-cell content [%] 96 95  95 4.2 6.4 8.0 Average cell size [μm] 77 9 61 72 75 212 D90 [μm] 101 n.s..sup.3) 86 92 107 316 .sup.1)calculated from specified porosity of 90 with typical PU density of 1150 kg/m.sup.3 .sup.2)not determined .sup.3)not specified .sup.4)determined according to hot wire method, see determination of thermal conductivity 1)

[0129] Example 1 shows that the insulation body produced with the process described in the present invention has a low lambda value. One less process step is required than in comparative example 3. There, the produced foam would still have to be laminated and evacuated.

[0130] Example 2 described in patent publication WO 2018/018571 A1 (here comparative example 2) shows that the process duration is markedly longer than in inventive example 1 and at 13 mW.Math.m.sup.−1K.sup.−1 thermal conductivity is markedly higher than in inventive example 1.

[0131] Comparative example 3 shows that the foam produced under comparable conditions without evacuation and a barrier film has a markedly higher lambda value.

[0132] The foam produced in comparative example 4 also exhibits a markedly higher lambda value than that in example 1 despite its closed-cell structure. Even with a decrease in apparent density from 71 to 45 kg/m.sup.3 and a closed-cell structure as shown in comparative example 5 the lambda value is still markedly higher than that in example 1.

[0133] The foam produced in comparative example 6 exhibits a markedly higher lambda value than that in inventive example 1 despite its closed-cell structure and foaming with pentane as blowing agent.