Rigid polyurethane foams with high acoustic absorption

Abstract

The present invention relates to predominantly (>50 vol %) open-cell (to DIN ISO 4590-5 86), cold-deformable, rigid polyurethane foams which possess high acoustic absorption and a uniform cell structure and which are suitable for producing automotive interior trim, more particularly roof linings and pillar trim.

Claims

1. An open-cell, cold-formable, consolidated, rigid polyurethane foam comprising >50 vol % open-cell content according to DIN ISO 4590-86 and having high, uniform acoustic absorption, obtained by reacting component A) comprising A1) 0 to 10 wt %, based on component A), of 2,2′-diphenyl-methane diisocyanate, A2) 0 to 30 wt %, based on component A), of 2,4′-diphenylmethane diisocyanate and A3) 25 to 75 wt %, based on component A), of 4,4′-diphenyl-methane diisocyanate, and component B) consisting of B1) 10 to 70 wt %, based on component B), of polyoxyalkylene polyols having a hydroxyl number of 25 to 110 mg KOH/g and a number-average functionality of 2 to 4, B2) 0 to 20 wt %, based on component B), of polyoxyalkylene polyols having a hydroxyl number of 150 to 550 mg KOH/g and a functionality of 2, B3) 10 to 66 wt %, based on component B), of polyoxyalkylene polyols having a hydroxyl number of 300 to 900 mg KOH/g and a number-average functionality of 2.5 to 4, B4) 2.5 to 25 wt %, based on component B), of polyoxyalkylene polyols having a hydroxyl number of 25 to 195 mg KOH/g and a functionality of 6, B5) 0 to 15 wt %, based on component B), of oligomeric polyester polyols having a hydroxyl number of 195 to 500 mg KOH/g and a number-average functionality of 2 to 5, B6) 0 to 8 wt %, based on component B), of glycerol, B7) 2.5 to 8 wt %, based on component B), of water, B8) 0.5 to 4 wt %, based on component B), of a catalyst, and B9) optionally auxiliaries and/or adjuvants, wherein the ratio of the number of NCO groups in component A) to the number of OH groups in component B) multiplied by 100 (NCO index) is in the range of 85 to 135.

2. The polyurethane foam according to claim 1, having a density according to DIN 53420 of 15 to 65 kg/m.sup.3.

3. The polyurethane foam according to claim 1, comprising a catalyst based on renewable raw materials in component B8).

4. A method comprising utilizing the polyurethane foam according to claim 1 in composite materials as sound absorbers.

5. A method for producing automotive interior trim, comprising utilizing the polyurethane foam according to claim 1.

6. An automotive interior trim, roof lining or pillar trim comprising the polyurethane foam according to claim 1.

7. The polyurethane foam according to claim 1, wherein the catalyst of component B8) is selected from the group consisting of fatty acid amides of diamines.

Description

INVENTIVE AND COMPARATIVE EXAMPLES

(1) Products Used:

(2) Niax® Silicone SR 234 and Niax® Silicone SR 272 from Momentive Performance Materials, Si foam stabilizer.

Production of the Rigid PU Foams

Inventive Example 1

(3) A mixture (component B) of

(4) 22.7 parts by weight of polyether alcohol (B1) based on glycerol/propylene oxide/ethylene oxide, OH number 35 mg KOH/g, functionality 3,

(5) 10.0 parts by weight of polyether alcohol (B2) based on 1,2-propylene glycol, OH number 260 mg KOH/g, functionality 2,

(6) 41.4 parts by weight of polyether alcohol (B3) based on glycerol, OH number 450 mg KOH/g, functionality 3,

(7) 8.8 parts by weight of polyether alcohol (B4) based on sorbitol/propylene oxide/ethylene oxide, OH number 28.5 mg KOH/g, functionality 6,

(8) 6.0 parts by weight of glycerol (B6)

(9) 3.0 parts by weight of reaction product of tall oil acid and N,N-dimethylaminopropylamine (B8)

(10) 1.5 parts by weight of silicone foam stabilizer (B9) (Niax® Silicone SR 272 from Momentive Performance Materials),

(11) 6.50 parts by weight of water (B7) and

(12) 0.10 part by weight of Isopur N black paste (B9) from ISL-Chemie of Kürten, DE

(13) was mixed with

(14) 165 parts by weight of a mixture (A component) of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates having a diphenylmethane diisocyanate isomer content of 60 wt % and an NCO content of 31.8 wt %. A1): 13.9 wt %, based on the organic polyisocyanate component A), of 2,4′-diphenylmethane diisocyanate and A2): 44.7 wt %, based on organic polyisocyanate component A), of 4,4′-diphenylmethane diisocyanate.

Comparative Example 1

(15) A mixture (component B) of

(16) 31.0 parts by weight of polyether alcohol (B1) based on glycerol/propylene oxide/ethylene oxide, OH number 28 mg KOH/g, functionality 3,

(17) 35.05 parts by weight of polyether alcohol (B3) based on trimethylolpropane/propylene oxide, OH number 550 mg KOH/g, functionality 3,

(18) 12.0 parts by weight of polyether alcohol (B2) based on propylene glycol/propylene oxide, OH number 512 mg KOH/g, functionality 2,

(19) 15.0 parts by weight of reaction product of phthalic anhydride, diethylene glycol and ethylene oxide, OH number 300 mg KOH/g, functionality 2 (B5),

(20) 0.50 part by weight of 1,1′-((3-(dimethylamino)propyl)imino)bis-2-propanol and 0.05 part by weight of bis(2-dimethylaminoethyl) ether (B8),

(21) 0.20 part by weight of silicone foam stabilizer (Niax® Silicone SR 234 from Momentive Performance Materials) (B9),

(22) 5.80 parts by weight of water (B7) and

(23) 0.50 part by weight of Isopur N black paste (B9) from ISL-Chemie of Kürten, DE

(24) was mixed with

(25) 175 parts by weight of a mixture (A component) of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates having a diphenylmethane diisocyanate isomer content of 60 wt % and an NCO content of 31.8 wt %. A1): 13.9 wt %, based on the organic polyisocyanate component A), of 2,4′-diphenylmethane diisocyanate and A2): 44.7 wt %, based on organic polyisocyanate component A), of 4,4′-diphenylmethane diisocyanate.

(26) Blocks with a block size of 30×30×30 cm were produced for the purpose of measuring the acoustic properties of the foam. Additionally, blocks in dimensions of 1.0×1.0×0.8 to 1.0 m and in dimensions of 1.4×2.2×1.0 m were produced for the purpose of assessing the homogeneity of the acoustic properties. Foam panels in 10 mm and 14 mm panel thickness were tested and evaluated.

(27) For this purpose, the bottom 15 cm of the foam blocks (1.4×2.2×1.0 m) were cut away. This region may have defects resulting from cell opening at the end of the reaction, and is therefore less suitable. Moreover, the cap of the foam block was cut away (approximately 10 cm). The foam block was split into panels, and then panels were taken from the bottom, middle and top regions, and the acoustic properties were measured in the Kundt tube.

(28) The table below contains the acoustic absorptions from Inventive Example 1 (foam block: 1.0×1.0×0.8 to 1.0 m). The table indicates the position from which the specimens measured were taken. In this context, CT denotes “corner top”, CM “corner middle”, CB “corner bottom”, MT “middle top”, MM “middle middle”, and MB “middle bottom”.

(29) TABLE-US-00001 Ave- Standard Frequency CT CM CB MT MM MB rage deviation Average 50% 49% 44% 51% 49% 50% 49% 8% 800-6350 Hz

(30) The physical properties of the foams as well become more homogeneous. The table below contains the physical properties from Inventive Example 1 (foam block: 1.0×1.0×0.8 to 1.0 m).

(31) TABLE-US-00002 Standard Standard MT MM MB CT CM CB Average deviation Gross density DIN 23.1 22.3 24.9 23.3 23.0 24.0 23.4 0.9 [kg/m.sup.3] 53420 Compression test DIN EN 0.09 0.10 0.12 0.08 0.11 0.11 0.10 0.015 [MPa] 826 Open-cell content DIN ISO 92 92 89 92 87 85.9 89.5 2.6 [Vol %] 4590-86 Tensile strength DIN 0.18 0.14 0.16 0.19 0.15 0.18 0.17 0.02 [MPa] 53430 Elongation at break DIN 14.2 14.8 15.8 14.1 15.7 15.7 15.05 0.8 [%] 53430

(32) The table below contains the acoustic absorptions from Comparative Example 1 (foam block: 1.0×1.0×0.8 to 1.0 m)

(33) TABLE-US-00003 Ave- Standard Frequency CT CM CB MT MM MB rage deviation Average 34% 41% 32% 39% 51% 39% 40% 9% 800-6350 Hz

(34) The table below contains the physical properties of the foams from Comparative Example 1 (foam block: 1.0×1.0×0.8 to 1.0 m)

(35) TABLE-US-00004 Standard Standard MT MM MB CT CM CB Average deviation Gross density DIN 24.24 21.91 24.54 24.68 22.34 23.62 23.56 1.17 [kg/m.sup.3] 53420 Compression test DIN EN 0.1 0.1 0.1 0.1 0.1 0.1 0.10 0.01 [MPa] 826 Open-cell content DIN SO 81 86 77 79 78 66 77.6 6.5 [vol %] 4590-86 Tensile strength DIN 0.227 0.163 0.177 0.223 0.169 0.192 0.192 0.027 [MPa] 53430 Elongation at DIN 15.2 16.7 20.8 14.3 22.5 17.4 17.80 3.19 break [%] 53430

(36) It was found that the use of hexafunctional polyethers resulted in higher average acoustic absorption in conjunction with improved homogeneity as represented by the standard deviation. The standard deviations in the gross density, open-cell content, tensile strength and elongation at break showed that in terms of these properties as well, the use of hexafunctional polyethers resulted in improved homogeneity.

Variation in the Mixing Ratio (Inventive Example 2)

(37) Foams below were produced by subjecting, in a cardboard beaker with a size of approximately 11, a mixture of component B), comprising

(38) 22.5 parts by weight of polyether alcohol (B1) based on glycerol/propylene oxide/ethylene oxide, OH number 35 mg KOH/g, functionality 3,

(39) 10.0 parts by weight of polyether alcohol (B2) based on 1,2-propylene glycol, OH number 260 mg KOH/g, functionality 2,

(40) 41.1 parts by weight of polyether alcohol (B3) based on glycerol, OH number 450 mg KOH/g, functionality 3,

(41) 8.7 parts by weight of polyether alcohol (B4) based on sorbitol/propylene oxide/ethylene oxide, OH number 28.5 mg KOH/g, functionality 6,

(42) 5.95 parts by weight of glycerol (B6),

(43) 3.1 parts by weight of reaction product of tall oil acid and N,N-dimethylaminopropylamine (B8),

(44) 1.5 parts by weight of silicone foam stability (B9) (Niax® Silicone SR 272 from Momentive Performance Materials) and 0.2 part by weight of silicone foam stabilizer (B9) (Niax® Silicone SR 234 from Momentive Performance Materials),

(45) 6.45 parts by weight of water (B7), and

(46) 0.50 part by weight of Isopur N black paste (B9),

(47) to mixing with I) 160 parts by weight of a mixture (A component) of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates having a diphenylmethane diisocyanate isomer content of 60 wt % and an NCO content of 31.8 wt % [A1): 13.9 wt %, based on the organic polyisocyanate component A), of 2,4′-diphenylmethane diisocyanate and A2): 44.7 wt %, based on organic polyisocyanate component A), of 4,4′-diphenyl-methane diisocyanate] or II) 180 parts by weight of a mixture (A component) of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates having a diphenylmethane diisocyanate isomer content of 60 wt % and an NCO content of 31.8 wt % [A1): 13.9 wt %, based on the organic polyisocyanate component A), of 2,4′-diphenylmethane diisocyanate and A2): 44.7 wt %, based on organic polyisocyanate component A), of 4,4′-diphenyl-methane diisocyanate] or III) 200 parts by weight of a mixture (A component) of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates having a diphenylmethane diisocyanate isomer content of 60 wt % and an NCO content of 31.8 wt % [A1): 13.9 wt %, based on the organic polyisocyanate component A), of 2,4′-diphenylmethane diisocyanate and A2): 44.7 wt %, based on organic polyisocyanate component A), of 4,4′-diphenyl-methane diisocyanate]
at 4200 rpm for 21 s, using a Pendraulic stirrer with a stirrer plate having a diameter of 6.5 cm. The table below contains the acoustic absorptions from Comparative Example 1 (foam block: about 0.3×0.3×0.3 m). The height varies somewhat and decreases from 31.8 cm to 29.0 cm as the mixing ratio goes up. The test specimens were taken from the middle of the foam.

(48) TABLE-US-00005 2a 2b 2c Isocyanate per 100 g polyol 160 g 180 g 200 g Average 800-6350 Hz 42% 46% 44%

(49) As can be seen from the table, the high acoustic absorption is obtained for all the mixing ratios.

Inventive Example 3

(50) A mixture (component B) of

(51) TABLE-US-00006 Component Formula 3a Formula 3b Formula 3c Polyether alcohol (B4) based on 15.00 20.00 31.20 sorbitol/propylene oxide/ethylene oxide, OH number 28.5 mg KOH/g, functionality 6 Polyether alcohol (B1) based on 16.20 11.20 glycerol/propylene oxide/ethylene oxide, OH number 35 mg KOH/g, functionality 3 Polyether alcohol (B2) based on 1,2-propylene 10.00 10.00 10.00 glycol, OH number 260 mg KOH/g, functionality 2 Polyether alcohol (B3) based on glycerol, 41.10 41.10 41.10 OH number 450 mg KOH/g, functionality 3 Glycerol (B6) 5.95 5.95 5.95 Water (B7) 6.45 6.45 6.45 Niax ® Silicone SR 272 (B9) 1.50 1.50 1.50 Niax ® Silicone SR 234 (B9) 0.20 0.20 0.20 Isopur N black paste 0.50 0.50 0.50 Reaction product of tall oil acid and 3.10 3.10 3.10 dimethylaminopropylamine (B8)
was mixed with

(52) 160 parts by weight of a mixture (A component) of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates having a diphenylmethane diisocyanate isomer content of 60 wt % and an NCO content of 31.8 wt % [A1): 13.9 wt %, based on the organic polyisocyanate component A), of 2,4′-diphenylmethane diisocyanate and A2): 44.7 wt %, based on organic polyisocyanate component A), of 4,4′-diphenylmethane diisocyanate].

(53) The table below contains the acoustic absorptions (foam block: about 0.3×0.3×0.3 m).

(54) TABLE-US-00007 3a 3b 3c Average 800-6350 Hz 51% 51% 46%