Process for producing porous materials

Abstract

The present invention relates to a process for preparing a porous material, at least providing a mixture (I) comprising a composition (A) comprising components suitable to form an organic gel and a solvent(B), reacting the components in the composition (A) in the presence of the solvent (B) to form a gel, and drying of the gel obtained in step b), wherein the composition (A) comprises a catalyst (C) selected from the group consisting of alkali metal and earth alkali metal salts of a saturated or unsaturated monocarboxylic acid with 4 to 8 carbon atoms. The invention further relates to the porous materials which can be obtained in this way and the use of the porous materials as thermal insulation material and in vacuum insulation panels, in particular in interior or exterior thermal insulation systems.

Claims

1. A process for preparing a porous material, the process comprising: a) providing a mixture (I) comprising (i) composition (A) comprising a catalyst (C) and components suitable to form an organic gel, and (ii) a solvent (B), b) reacting the components in the composition (A) in the presence of the solvent (B) to form a gel, and c) drying the gel obtained in b), wherein the catalyst (C) is selected from the group consisting of an alkali metal linear saturated monocarboxylic acid with 4 to 7 carbon atoms, an earth alkali metal salt of linear saturated monocarboxylic acid with 4 to 7 carbon atoms, an alkali metal linear unsaturated monocarboxylic acid with 4 to 7 carbon atoms, an alkali metal salt of a linear unsaturated monocarboxylic acid with 4 to 7 carbon atoms, and a combination thereof.

2. The process according to claim 1, wherein the catalyst (C) is selected from the group consisting of an alkali metal salt of a linear unsaturated monocarboxylic acid with 4 to 7 carbon atoms and an earth alkali metal salt of a linear unsaturated monocarboxylic acid with 4 to 7 carbon atoms.

3. The process according to claim 1, wherein the catalyst (C) is selected from the group consisting of an alkali metal sorbate and an earth alkali metal sorbate.

4. The process according to claim 1, wherein the catalyst (C) is present in the composition (A) in an amount of from 0.1 to 30% by weight, based on a total weight of the composition (A).

5. The process according to claim 1, wherein the composition (A) comprises a glycol.

6. The process according to claim 5, wherein the composition (A) comprises a glycol selected from the group consisting of monoethylene glycol (MEG), diethylene glycol (DEG), triethylene glycol (TrEG), tetraethylene glycol (TeEG), pentaethylene glycol (PeEG), hexaethylene glycol (HeEG), octaethylene glycol (OcEG), monopropylene glycol (MPG), dipropylene glycol (DPG), tripropylene glycol (TrPG), tetrapropylene glycol (TePG), pentapropylene (PePG), hexapropylene glycol (HePG), and octapropylene glycol (OcPG).

7. The process according claim 5, wherein the catalyst (C) is mixed with the glycol to give a composition (C*).

8. The process according to claim 1, wherein the composition (A) comprises at least one monool (am).

9. The process according to claim 1, wherein the composition (A) comprises at least one polyfunctional isocyanate as component (a1).

10. The process according to claim 1, wherein the composition (A) comprises at least one polyfunctional isocyanate as component (a1), at least one aromatic amine as component (a2), optionally water as component (a3), and optionally at least one further catalyst as component (a4).

11. The process according to claim 10, wherein the at least one aromatic amine is a polyfunctional aromatic amine.

12. The process according to claim 10, wherein the at least one aromatic amine (a2) is represented by formula I: ##STR00010## where R.sup.1 and R.sup.2 are each independently selected from the group consisting of hydrogen and a linear or branched alkyl group comprising from 1 to 6 carbon atoms and Q.sup.1 to Q.sup.5 and Q.sup.1 to Q.sup.5 are each independently selected from the group consisting of hydrogen, a primary amino group, and a linear or branched alkyl group comprising from 1 to 12 carbon atoms, where the alkyl group optionally comprises a functional group, with the proviso that the at least one aromatic amine represented by the formula I comprises at least two primary amino groups, where at least one of Q.sup.1, Q.sup.3 and Q.sup.5 is a primary amino group and at least one of Q.sup.1, Q.sup.3 and Q.sup.5 is a primary amino group.

13. The process according to claim 11, wherein the composition (A) comprises (a0) from 0.1 to 30% by weight of the catalyst (C), (a1) from 25 to 94.9% by weight of the at least one polyfunctional isocyanate, and (a2) from 0.1 to 30% by weight of the at least one polyfunctional aromatic amine, which is represented by formula I; ##STR00011## where R.sup.1 and R.sup.2 are each independently selected from the group consisting of hydrogen and a linear or branched alkyl group comprising from 1 to 6 carbon atoms and Q.sup.1 to Q.sup.5 and Q.sup.1 to Q.sup.5 are each independently selected from the group consisting of hydrogen, a primary amino group, and a linear or branched alkyl group comprising from 1 to 12 carbon atoms, where the alkyl group optionally comprises a functional group, with the proviso that the at least one polyfunctional aromatic amine represented by the formula I comprises at least two primary amino groups, where at least one of Q.sup.1, Q.sup.3 and Q.sup.5 is a primary amino group and at least one of Q.sup.1, Q.sup.3 and Q.sup.5 is a primary amino group, (a3) from 0 to 15% by weight of water, and (a4) from 0 to 29.9% by weight of the at least one further catalyst, based on a total weight of the components (a0) to (a4), where the % by weight of the components (a0) to (a4) adds up to 100% by weight, and wherein a sum of the components (a0) and (a4) is in the range of from 0.1 to 30% by weight based on the total weight of the components (a0) to (a4).

14. The process according to claim 10, wherein the at least one aromatic amine component (a2) comprises at least one compound selected from the group consisting of 3,3,,5,5-tetraalkyl-4,4-diaminodiphenylmethane, 3,3,5,5-tetraalkyl-2,2-diaminodiphenylmethane and 3,3,5,5-tetraalkyl-2,4-diaminodiphenylmethane, where the alkyl groups in the 3,3,5 and 5 positions are independently a linear or branched alkyl group comprising from 1 to 12 carbon atoms and optionally a functional group.

15. The process according to claim 10, wherein the composition (A) comprises the at least one further catalyst, (a4), which catalyzes trimerization to form at least one isocyanurate group.

16. The process according to claim 10, wherein the composition (A) comprises the at least one further catalyst (a4), which comprises at least one tertiary amino group.

17. The process according to claim 1, wherein no water is used.

18. The process according to claim 1, wherein the drying c) is carried out by converting liquid comprised in the gel into a gaseous state at a temperature and a pressure below a critical temperature and a critical pressure of the liquid comprised in the gel.

19. The process according to claim 1, wherein the drying c) is carried out under supercritical conditions.

20. A porous material, obtained or obtainable by the process according to claim 1.

21. A method of making a thermal insulation material or a vacuum insulation panel, the method comprising preparing the thermal insulation material or the vacuum insulation panel with the porous materials according to claim 20.

22. The method according to claim 21, wherein the porous material is used in interior or exterior thermal insulation systems.

Description

EXAMPLES

(1) 1. Methods

(2) 1.1 Determination of Thermal Conductivity

(3) The thermal conductivity was measured according to DIN EN 12667 with a heat flow meter from Hesto (Lambda Control A50).

(4) 1.2 Solvent Extraction with Supercritical Carbon Dioxide

(5) One or several gel monoliths were placed onto sample trays in an autoclave of 25 l volume. Subsequent to filling with supercritical carbon dioxide (scCO.sub.2), the gelation solvent was removed (drying) by flowing scCO.sub.2 through the autoclave for 24 h (20 kg/h). Process pressure was kept between 120 and 130 bar and process temperature at 45 C. in order to maintain carbon dioxide in a supercritical state. At the end of the process, the pressure was reduced to normal atmospheric pressure in a controlled manner while maintaining the system at a temperature of 45 C. The autoclave was opened, and the obtained porous monoliths were removed.

(6) 1.3 Determination of Compressive Strength and E Modulus

(7) The compressive strength and the elastic modulus was measured according to DIN 53421 with 10% strain.

(8) 2. Materials

(9) Component a1: oligomeric MDI (Lupranat M200) having an NCO content of 30.9 g per 100 g accordance with ASTM D-5155-96 A, a functionality in the region of three and a viscosity of 2100 mPa.Math.s at 25 C. in accordance with DIN 53018 (hereafter M200) Component a2: 3,3,5,5-Tetraethyl-4,4diaminodiphenylmethane (hereinafter MDEA) Catalysts: Dabco K15 (potassium ethylhexanoate dissolved in diethylene glycol (85%)) Potassium sorbate dissolved in monoethylene glycol (20%) Urea dissolved in monoethylene glycol (20%) Potassium benzoate dissolved in monoethylene glycol (20%)
3. Examples

(10) Thermal conductivity values for all examples are shown in Table 1. Furthermore, data regarding the compressive strength and density are included for several examples.

(11) 3.1 Example 1 (Comparative):

(12) In a polypropylene container, 1 g graphite, 1 g melamine and 48 g M200 were stirred in 220 g MEK at 20 C. leading to a black solution with dispersed graphite and melamine. Similarly, 12 g MDEA, 4 g Dabco K15, 8 g butanol and 4 g water were dissolved in 220 g MEK to obtain a second solution. The solutions were combined in a rectangular container (2020 cm5 cm height) by pouring one solution into the other, which led to a clear, homogeneous mixture of low viscosity. The container was closed with a lid and the mixture was gelled at room temperature for 24 h. The resulting monolithic gel slab was dried through solvent extraction with scCO.sub.2 in a 25 l autoclave leading to a porous material.

(13) The compressive strength was determined according to DIN 53421 with 10% strain.

(14) The elastic modulus was 5.07 N/mm.sup.2.

(15) 3.2 Example 2 (Comparative):

(16) In a polypropylene container, 1 g graphite and 48 g M200 were stirred in 220 g MEK at 20 C. leading to a black solution with dispersed graphite. Similarly, 12 g MDEA, 4 g Dabco K15, 12 g butanol and 4 g water were dissolved in 220 g MEK to obtain a second solution. The solutions were combined in a rectangular container (2020 cm5 cm height) by pouring one solution into the other, which led to a clear, homogeneous mixture of low viscosity. The container was closed with a lid and the mixture was gelled at room temperature for 24 h. The resulting monolithic gel slab was dried through solvent extraction with scCO.sub.2 in a 25 l autoclave leading to a porous material.

(17) The compressive strength was determined according to DIN 53421 with 10% strain.

(18) The elastic modulus was 5.5 N/mm.sup.2.

(19) 3.3 Example 3 (Comparative):

(20) In a polypropylene container, 48 g M200 were stirred in 220 g MEK at 20 C. leading to a clear solution. Similarly, 8 g MDEA, 4 g Dabco K15, 8 g butanol were dissolved in 220 g MEK to obtain a second solution. The solutions were combined in a rectangular container (2020 cm5 cm height) by pouring one solution into the other, which led to a clear, homogeneous mixture of low viscosity. The container was closed with a lid and the mixture was gelled at room temperature for 24 h. The resulting monolithic gel slab was fragile and broke.

(21) Fragments of the gel slab were dried through solvent extraction with scCO.sub.2 in a 25 l autoclave leading to a porous material. Non uniform shrinkage of the fragments was observed.

(22) 3.4 Example 4 (Comparative):

(23) In a polypropylene container, 48 g M200 were stirred in 220 g MEK at 20 C. leading to a clear solution. Similarly, 8 g MDEA and 4 g Dabco K15 were dissolved in 220 g MEK to obtain a second solution. The solutions were combined in a rectangular container (2020 cm5 cm height) by pouring one solution into the other, which led to a homogeneous mixture of low viscosity. The container was closed with a lid and the mixture was gelled at room temperature for 24 h. The resulting monolithic gel slab was fragile and broke.

(24) Fragments of the gel slab were dried through solvent extraction with scCO.sub.2 in a 25 l autoclave leading to a porous material. Non uniform shrinkage of the fragments was observed.

(25) 3.5 Example 5 (Comparative):

(26) In a polypropylene container, 48 g M200 were stirred in 220 g MEK at 20 C. leading to a clear solution. Similarly, 8 g MDEA, 4 g Dabco K15 and 4 g water were dissolved in 220 g MEK to obtain a second solution. The solutions were combined in a rectangular container (2020 cm5 cm height) by pouring one solution into the other, which led to a clear, homogeneous mixture of low viscosity. The container was closed with a lid and the mixture was gelled at room temperature for 24 h. The resulting monolithic gel slab was dried through solvent extraction with scCO.sub.2 in a 25 l autoclave leading to a porous material.

(27) The compressive strength was determined according to DIN 53421 with 10% strain.

(28) The elastic modulus was 4.63 N/mm.sup.2.

(29) 3.6 Example 6:

(30) In a polypropylene container, 1 g graphite, 1 g melamine and 48 g M200 were stirred in 220 g MEK at 20 C. leading to a black solution with dispersed graphite and melamine. Similarly, 12 g MDEA, 4 g Ksorbate solution, 8 g butanol and 4 g water were dissolved in 220 g MEK to obtain a second solution. The solutions were combined in a rectangular container (2020 cm5 cm height) by pouring one solution into the other, which led to a homogeneous mixture of low viscosity. The container was closed with a lid and the mixture was gelled at room temperature for 24 h. The resulting monolithic gel slab was dried through solvent extraction with scCO.sub.2 in a 25 l autoclave leading to a porous material.

(31) The compressive strength was determined according to DIN 53421 with 10% strain.

(32) The elastic modulus was 7.67 N/mm.sup.2.

(33) 3.7 Example 7:

(34) In a polypropylene container, 1 g graphite and 48 g M200 were stirred in 220 g MEK at 20 C. leading to a black solution with dispersed graphite. Similarly, 12 g MDEA, 4 g Ksorbate solution, 12 g butanol and 4 g water were dissolved in 220 g MEK to obtain a second solution. The solutions were combined in a rectangular container (2020 cm5 cm height) by pouring one solution into the other, which led to a homogeneous mixture of low viscosity. The container was closed with a lid and the mixture was gelled at room temperature for 24 h. The resulting monolithic gel slab was dried through solvent extraction with scCO.sub.2 in a 25 l autoclave leading to a porous material.

(35) The compressive strength was determined according to DIN 53421 with 10% strain.

(36) The elastic modulus was 15.33 N/mm.sup.2.

(37) 3.8 Example 8:

(38) In a polypropylene container, 1 g graphite and 48 g M200 were stirred in 220 g MEK at 20 C. leading to a black solution with dispersed graphite. Similarly, 8 g MDEA, 4 g Ksorbate solution, 4 g urea solution, 8 g butanol and 4 g water were dissolved in 220 g MEK to obtain a second solution. The solutions were combined in a rectangular container (2020 cm5 cm height) by pouring one solution into the other, which led to a clear, homogeneous mixture of low viscosity. The container was closed with a lid and the mixture was gelled at room temperature for 24 h. The resulting monolithic gel slab was dried through solvent extraction with scCO.sub.2 in a 25 l autoclave leading to a porous material.

(39) The compressive strength was determined according to DIN 53421 with 10% strain.

(40) The elastic modulus was 21.05 N/mm.sup.2.

(41) 3.9 Example 9:

(42) In a polypropylene container, 48 g M200 were dissolved under stirring in 220 g MEK at 20 C. leading to a clear solution. Similarly, 8 g MDEA, 4 g Ksorbate solution and 8 g butanol were dissolved in 220 g MEK to obtain a second solution. The solutions were combined in a rectangular container (2020 cm5 cm height) by pouring one solution into the other, which led to a clear, homogeneous mixture of low viscosity. The container was closed with a lid and the mixture was gelled at room temperature for 24 h. The resulting monolithic gel slab was dried through solvent extraction with scCO.sub.2 in a 25 l autoclave leading to a porous material.

(43) The compressive strength was determined according to DIN 53421 with 10% strain.

(44) The elastic modulus was 16.65 N/mm.sup.2.

(45) 3.10 Example 10:

(46) In a polypropylene container, 48 g M200 were dissolved under stirring in 220 g MEK at 20 C. leading to a clear solution. Similarly, 8 g MDEA and 4 g Ksorbate solution were dissolved in 220 g MEK to obtain a second solution. The solutions were combined in a rectangular container (2020 cm5 cm height) by pouring one solution into the other, which led to a clear, homogeneous mixture of low viscosity. The container was closed with a lid and the mixture was gelled at room temperature for 24 h. The resulting monolithic gel slab was dried through solvent extraction with scCO.sub.2 in a 25 l autoclave leading to a porous material.

(47) The compressive strength was determined according to DIN 53421 with 10% strain.

(48) The elastic modulus was 7.90 N/mm.sup.2.

(49) 3.11 Example 11:

(50) In a polypropylene container, 36 g M200 were dissolved under stirring in 220 g MEK at 20 C. leading to a clear solution. Similarly, 8 g MDEA and 4 g Ksorbate solution were dissolved in 220 g MEK to obtain a second solution. The solutions were combined in a rectangular container (2020 cm5 cm height) by pouring one solution into the other, which led to a homogeneous mixture of low viscosity. The container was closed with a lid and the mixture was gelled at room temperature for 24 h. The resulting monolithic gel slab was dried through solvent extraction with scCO.sub.2 in a 25 l autoclave leading to a porous material.

(51) The compressive strength was determined according to DIN 53421 with 10% strain.

(52) The elastic modulus was 4.85 N/mm.sup.2.

(53) 3.12 Example 12:

(54) In a polypropylene container, 48 g M200 were dissolved under stirring in 220 g MEK/DEK 72:28 (v:v) at 20 C. leading to a clear solution. Similarly, 8 g MDEA and 4 g Ksorbate solution were dissolved in 220 g MEK to obtain a second solution. The solutions were combined in a rectangular container (2020 cm5 cm height) by pouring one solution into the other, which led to a homogeneous mixture of low viscosity. The container was closed with a lid and the mixture was gelled at room temperature for 24 h. The resulting monolithic gel slab was dried through solvent extraction with scCO.sub.2 in a 25 l autoclave leading to a porous material.

(55) The compressive strength was determined according to DIN 53421 with 10% strain.

(56) The elastic modulus was 16.27 N/mm.sup.2.

(57) 3.13 Example 13:

(58) In a polypropylene container, 48 g M200 were dissolved under stirring in 220 g DEK at 20 C. leading to a clear solution. Similarly, 8 g MDEA and 4 g Ksorbate solution were dissolved in 220 g MEK to obtain a second solution. The solutions were combined in a rectangular container (2020 cm5 cm height) by pouring one solution into the other, which led to a homogeneous mixture of low viscosity. The container was closed with a lid and the mixture was gelled at room temperature for 24 h. The resulting monolithic gel slab was dried through solvent extraction with scCO.sub.2 in a 25 l autoclave leading to a porous material.

(59) The compressive strength was determined according to DIN 53421 with 10% strain.

(60) The elastic modulus was 16.36 N/mm.sup.2.

(61) 3.14 Example 14:

(62) In a polypropylene container, 48 g M200 were dissolved under stirring in 220 g MEK at 20 C. leading to a clear solution. Similarly, 8 g MDEA, 4 g Kbenzoate solution and 4 g water were dissolved in 220 g MEK to obtain a second solution. The solutions were combined in a rectangular container (2020 cm5 cm height) by pouring one solution into the other, which led to a homogeneous mixture of low viscosity. The container was closed with a lid and the mixture was gelled at room temperature for 24 h. The resulting monolithic gel slab was dried through solvent extraction with scCO.sub.2 in a 25 l autoclave leading to a porous material.

(63) 3.15 Example 15:

(64) In a polypropylene container, 48 g M200 were dissolved under stirring in 220 g MEK at 20 C. leading to a clear solution. Similarly, 8 g MDEA and 4 g Kbenzoate solution were dissolved in 220 g MEK to obtain a second solution. The solutions were combined in a rectangular container (2020 cm5 cm height) by pouring one solution into the other, which led to a homogeneous mixture of low viscosity. The container was closed with a lid and the mixture was gelled at room temperature for 24 h. The resulting monolithic gel slab was dried through solvent extraction with scCO.sub.2 in a 25 l autoclave leading to a porous material.

(65) 4. Results

(66) TABLE-US-00001 TABLE 1 Results. Thermal conductivity Compression Density [mW/m*K] strength [kg/m.sup.3] (p = 1 bar, T = 10 C.) [kPa] Example 1 (comparative) 135 16.1 297 (12 g MDEA, K15, H.sub.2O, 8 g butanol) + 1 g graphite + 1 g melamine Example 2 (comparative) 130 15.8 306 (12 g MDEA, K15, H.sub.2O, 12 g butanol) + 1 g graphite Example 3 (comparative) n.d. n.d. n.d. (8 g MDEA, K15, 8 g butanol) Example 4 (comparative) n.d. n.d. n.d. (8 g MDEA, K15) Example 5 (comparative) 125 18.0 245 (8 g MDEA, K14, H.sub.2O) Example 6 115 17.1 561 (12 g MDEA, Ksorbate solution, H.sub.2O, 8 g butanol) + 1 g graphite + 1 g melamine Example 7 116 17.2 595 (12 g MDEA, Ksorbate solution, H.sub.2O, 12 g butanol) + 1 g graphite Example 8 130 17.7 798 (12 g MDEA, Ksorbate solution, H.sub.2O, 8 g butanol + urea solution) + 1 g graphite Example 9 119 18.6 546 (8 g MDEA, Ksorbate solution, 8 g butanol) Example 10 121 18.6 487 (8 g MDEA, Ksorbate solution) Example 11 99 18.3 294 (36 g M200, 8 g MDEA, Ksorbate solution) Example 12 134 19.0 701 (8 g MDEA, Ksorbate solution, 8 g butanol) in MEK/DEK 72:28 Example 13 137 19.3 795 (8 g MDEA, Ksorbate solution, 8 g butanol) in DEK Example 14 107 19.2 440 (8 g MDEA, Kbenzoate solution, H.sub.2O) Example 15 123 18.5 538 (8 g MDEA, Kbenzoate solution)
5. Abbreviations

(67) H.sub.2O Water

(68) K15 Dabco K15 (PUR catalyst)

(69) Ksorbate solution potassium sorbate dissolved in monoethylene glycol

(70) Urea solution urea dissolved in monoethylene glycol

(71) Kbenzoate solution potassium benzoate dissolved in monoethylene glycol

(72) M200 Lupranate M200 (polyisocyanate)

(73) MEK Methyl ethyl ketone

(74) DEK Diethyl ketone

(75) MDEA 4,4-Methylene-bis(2,6-diethylaniline)