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 system (CS) comprising a catalyst component (C1) selected from the group consisting of alkali metal and earth alkali metal, ammonium, ionic liquid salts of a saturated or unsaturated monocarboxylic acid and a carboxylic acid as catalyst component (C2). 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 as well as in water tank or ice maker insulation systems.

Claims

1: A process for preparing a porous material, the process comprising: a) providing a mixture (I) comprising (i) a composition (A) comprising 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 of the gel obtained in step b), wherein the composition (A) comprises a catalyst system (CS) comprising a catalyst component (C1) selected from the group consisting of alkali metal and earth alkali metal, ammonium, ionic liquid salts of a saturated or unsaturated monocarboxylic acid and a carboxylic acid as catalyst component (C2).

2: The process according to claim 1, wherein the catalyst component (C1) is selected from the group consisting of alkali metal and earth alkali metal, ammonium, ionic liquid salts of a saturated or unsaturated monocarboxylic acid with 2 to 8 carbon atoms.

3: The process according to claim 1, wherein the catalyst component (C2) is selected from the group of saturated or unsaturated monocarboxylic acids with 2 to 12 carbon atoms.

4: The process according to claim 1, wherein the catalyst component (C1) is selected from the group consisting of alkali metal and earth alkali metal salts of a saturated or unsaturated monocarboxylic acid with 2 to 8 carbon atoms and wherein the catalyst component (C2) is selected from the group of saturated or unsaturated monocarboxylic acids with 2 to 12 carbon atoms.

5: The process according to claim 1, wherein the catalyst system (CS) is present in the composition (A) in an amount in the range of from 0.1 to 30% by weight, based on the total weight of the composition (A).

6: The process according to claim 4, wherein the catalyst system (CS) comprises catalyst components (C1) and (C2) in a ratio in the range of from 1:10 to 10:1.

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

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

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

10: The process according to claim 9, wherein the at least one aromatic amine is a polyfunctional aromatic amine.

11: The process according to claim 9, wherein the at least one aromatic amine (a2) has the general formula I ##STR00006## where R.sup.1 and R.sup.2 can be identical or different and are each selected independently from among hydrogen and linear or branched alkyl groups having from 1 to 6 carbon atoms and all substituents Q.sup.1 to Q.sup.5 and Q.sup.1 to Q.sup.5 are identical or different and are each selected independently from among hydrogen, a primary amino group and a linear or branched alkyl group having from 1 to 12 carbon atoms, where the alkyl group can bear further functional groups, with the proviso that the compound having the general 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.

12: The process according to claim 1, wherein composition (A) comprises (a0) from 0.1 to 30% by weight of catalyst system (CS), (a1) from 25 to 94.9% by weight of at least one polyfunctional isocyanate, and (a2) from 0.1 to 30% by weight of at least one polyfunctional aromatic amine having the general formula I ##STR00007## where R.sup.1 and R.sup.2 can be identical or different and are each selected independently from among hydrogen and linear or branched alkyl groups having from 1 to 6 carbon atoms and all substituents Q.sup.1 to Q.sup.5 and Q.sup.1 to Q.sup.5 are identical or different and are each selected independently from among hydrogen, a primary amino group and a linear or branched alkyl group having from 1 to 12 carbon atoms, where the alkyl group can bear further functional groups, with the proviso that the compound having the general 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 at least one further catalyst, in each case based on the 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 the 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).

13: The process according to claim 9, wherein the 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 can be identical or different and are selected independently from among linear or branched alkyl groups which have from 1 to 12 carbon atoms and can bear further functional groups.

14: The process according to claim 8, wherein component (a4) catalyzes the trimerization to form isocyanurate groups.

15: The process according to claim 9, wherein component (a4) comprises at least one tertiary amino group.

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

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

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

19: A porous material, which is obtained by the process according to claim 1.

20: A thermal insulation material, comprising the porous material of claim 19.

21: The thermal insulation material according to claim 20, wherein the porous material is adapted to function as a thermal insulation material for interior or exterior thermal insulation systems.

22: The thermal insulation material according to claim 20, wherein the porous material is adapted to function as a thermal insulation material for water tank or ice maker thermal insulation systems.

Description

EXAMPLES

1. Methods

[0256] 1.1 Determination of Thermal Conductivity

[0257] The thermal conductivity was measured according to DIN EN 12667 with a heat flow meter from Hesto (Lambda Control A50).

[0258] 1.2 Solvent Extraction with Supercritical Carbon Dioxide

[0259] 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.

[0260] 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.

[0261] 1.3 Determination of Compressive Strength and E Modulus

[0262] The compressive strength and the elastic modulus were measured according to DIN 53421 with 10% strain.

2. Materials

[0263] 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) [0264] Component a2: 3,3,5,5-Tetraethyl-4,4diaminodiphenylmethane (hereinafter MDEA) [0265] Catalysts: Dabco K15 (potassium ethylhexanoate dissolved in diethylene glycol (85%)) [0266] Potassium sorbate dissolved in monoethylene glycol (20%) [0267] Potassium acetate dissolved in tetraethylene glycol (20%) [0268] Potassium benzoate dissolved in monoethylene glycol (20%) [0269] Butyldiethanolamin [0270] Carboxylic acids: Propionic acid [0271] Acetic acid

3. Examples

[0272] Thermal conductivity values for all examples are shown in Table 1. Furthermore, data regarding the compressive strength and density are included for several examples.

3.1 Example 1 (Comparative)

[0273] 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, 1 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.

[0274] The compressive strength was determined according to DIN 53421 with 10% strain.

[0275] The elastic modulus was 6.68 N/mm.sup.2.

3.2 Example 2

[0276] 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, 1 g Ksorbate solution and 0.8 g acetic acid 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.

[0277] The compressive strength was determined according to DIN 53421 with 10% strain.

[0278] The elastic modulus was 9.56 N/mm.sup.2.

3.3 Example 3 (Comparative)

[0279] 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, 1 g Ksorbate solution and 6 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 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.

[0280] The compressive strength was determined according to DIN 53421 with 10% strain.

[0281] The elastic modulus was 8.32 N/mm.sup.2.

3.4 Example 4

[0282] 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, 1 g Ksorbate solution, 6 g butanol and 1 g propionic acid 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.

[0283] The compressive strength was determined according to DIN 53421 with 10% strain.

[0284] The elastic modulus was 8.55 N/mm.sup.2.

3.5 Example 5

[0285] 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, 1 g Ksorbate solution, 4 g BDeoA, 6 g butanol and 1 g propionic acid 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.

[0286] The compressive strength was determined according to DIN 53421 with 10% strain.

[0287] The elastic modulus was 14.52 N/mm.sup.2.

3.6 Example 6 (Comparative)

[0288] 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 Kacetate 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 sedimentation of undissolved particles.

3.7 Example 7

[0289] 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 Kacetate solution and 4 g water and 1 g acetic acid 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.

[0290] The compressive strength was determined according to DIN 53421 with 10% strain.

[0291] The elastic modulus was 13.59 N/mm.sup.2.

3.8 Example 8

[0292] 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, 1 g Kacetate solution and 1 g acetic acid 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.

[0293] The compressive strength was determined according to DIN 53421 with 10% strain.

[0294] The elastic modulus was 13.80 N/mm.sup.2.

3.9 Example 9 (comparative)

[0295] 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, 1 g 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 broken upon handling and subsequently not supercritically dried.

3.10 Example 10

[0296] 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, 1 g K15 and 1 g propionic acid 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.

[0297] The compressive strength was determined according to DIN EN ISO 844 with 6.6% strain.

[0298] The elastic modulus was 16.52 N/mm.sup.2.

3.11 Example 11 (Comparative)

[0299] 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 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.

[0300] The compressive strength was determined according to DIN EN ISO 844 with 5.7% strain.

[0301] The elastic modulus was 16.63 N/mm.sup.2.

3.12 Example 12

[0302] 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 Kbenzoate solution and 1 g acetic acid 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.

[0303] The compressive strength was determined according to DIN EN ISO 844 with 6.3% strain.

[0304] The elastic modulus was 12.52 N/mm.sup.2.

3.13 Example 13

[0305] 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 Kbenzoate solution and 1 g propionic acid 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.

[0306] The compressive strength was determined according to DIN EN ISO 844 with 6.0% strain.

[0307] The elastic modulus was 12.75 N/mm.sup.2.

4. Results

[0308]

TABLE-US-00001 TABLE 1 Results. Thermal conductivity Compressive Density [mW/m * K] strength [kg/m.sup.3] (p = 1 bar, T = 10 C.) [kPa] Example 1 (comparative) 105 18.9 338 (8 g MDEA, 1 g Ksorbate solution) Example 2 107 18.5 353 (8 g MDEA, 1 g Ksorbate solution) + acetic acid Example 3 (comparative) 121 18.5 561 8 g MDEA, 1 g Ksorbate solution, 6 g butanol) Example 4 121 17.8 598 8 g MDEA, 1 g Ksorbate solution, 6 g butanol + propionic acid) Example 5 130 17.9 635 8 g MDEA, 1 g Ksorbate solution, 6 g BDeoA + propionic acid) Example 6 (comparative) Sedimentation of (8 g MDEA, 4 g Kacetate solution, water) undissolved particles Example 7 111 18.8 484 (8 g MDEA, 1 g Kacetate solution, water) + acetic acid Example 8 117 18.2 571 (8 g MDEA, 1 g Kacetate solution) + acetic acid Example 9 (comparative) Wet gel broken (8 g MDEA, 1 g K15,) Example 10 117 18.1 443 (8 g MDEA, 1 g K15) + propionic acid Example 11 123 18.5 538 (8 g MDEA, 4 g Kbenzoate solution) Example 12 121 18.0 477 (8 g MDEA, 4 g Kbenzoate solution) + acetic acid Example 13 121 18.0 509 (8 g MDEA, 4 g Kbenzoate solution) + propionic acid

5. Abbreviations

[0309] H.sub.2O Water

[0310] K15 Dabco K15 (PUR catalyst)

[0311] Ksorbate solution potassium sorbate dissolved in monoethylene glycol

[0312] Kacetate solution potassium acetate dissolved in tetraethylene glycol

[0313] Kbenzoate solution potassium benzoate dissolved in monoethylene glycol

[0314] M200 Lupranate M200 (polyisocyanate)

[0315] MEK Methyl ethyl ketone

[0316] MDEA 4,4-Methylene-bis(2,6-diethylaniline)