Process for producing porous materials

Abstract

The present invention relates to a process for preparing a porous material, at least comprising the steps of providing a mixture (I) comprising a composition (A) comprising at least one monool (am) and 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). 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, comprising: a) providing a mixture (I) comprising (i) a composition (A) comprising a monool (am) and a composition (A*) comprising: a polyfunctional isocyanate as component (a1), at least one aromatic amine as component (a2), optionally, water as component (a3), and optionally at least one catalyst as component (a4); and (ii) a solvent (B), b) reacting the components of the composition (A) in the solvent (B) to form a mixture of an organic gel in the solvent (B), and c) drying of the mixture to remove the solvent (B) and obtain the organic gel as the porous material obtained in b), wherein the at least one aromatic amine (a2) is a polyfunctional aromatic amine, the monool is present in the composition (A) in an amount of from 0.5 to 25% by weight based on the composition (A).

2. The process according to claim 1, wherein the monool is selected from the group consisting of aliphatic monools with 1 to 20 carbon atoms and aromatic monools with 1 to 20 carbon atoms.

3. The process according to claim 1, 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 the group consisting of 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 the group consisting of 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.

4. The process according to claim wherein composition (A*) comprises (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 the group consisting of 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 the group consisting of 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, (a4) from 0.1 to 30% by weight of at least one catalyst, and in each case based on the total weight of the components (a1), (a2), (a3), and (a4), where the % by weight of the components (a1), (a2), (a3), and (a4) add up to 100% by weight.

5. The process according to claim 1, 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 the group consisting of linear or branched alkyl groups which have from 1 to 12 carbon atoms and can bear further functional groups.

6. The process according to claim 1, wherein component (a4) is present and is selected from the group consisting of primary, secondary and tertiary amines, triazine derivatives, metal-organic compounds, metal chelates, oxides of phospholenes, quaternary ammonium salts, ammonium hydroxides and alkali metal and alkaline earth metal hydroxides, alkoxides and carboxylates.

7. The process according to claim 1, wherein at least one catalyst as component (a4) is present and the catalyst (a4) catalyzes trimerization of the at least one polyfunctional isocyanate to form isocyanurate groups.

8. The process according to claim 1, wherein at least 0.1% by weight of water as component (a3) is added.

9. The process according to claim 1, wherein the drying according to 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.

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

11. The porous material according to claim 10, wherein the drying according to c) is carried out under supercritical conditions.

12. A thermal insulation material or a vacuum insulation panel comprising the porous material according to claim 10.

13. An interior or exterior thermal insulation system comprising the thermal insulation material or the vacuum insulation panel according to claim 12.

Description

EXAMPLES

1. Methods

(1) 1.1 Determination of Thermal Conductivity

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

(3) 1.2 Solvent Extraction with Supercritical Carbon Dioxide

(4) 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.

(5) 1.3 Water Uptake Test

(6) The mass of a sample was determined before and after soaking it completely under water for one hour. The water uptake was calculated accordingly in relation to the weight of the sample. After drying the sample for two hours at 100 C. the shrinkage and the surface appearance was investigated.

2. Materials

(7) 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)

(8) Component a2: 3,3,5,5-Tetraethyl-4,4diaminodiphenylmethane (hereinafter MDEA)

(9) Catalyst: Dabco K15 (potassium ethylhexanoate dissolved in diethylene glycol (85%))

3. Examples

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

3.1 Example 1 (Comparative)

(11) In a polypropylene container, 48 g M200 were dissolved under stirring in 220 g MEK at 20 C. leading to a clear solution. Similarly, 12 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.

3.2 Example 2

(12) In a polypropylene container, 48 g M200 were dissolved under stirring in 220 g MEK at 20 C. leading to a clear solution. Similarly, 12 g MDEA, 4 g Dabco K15, 16 g hexadecanol 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.

3.3 Example 3

(13) In a polypropylene container, 48 g M200 were dissolved under stirring in 220 g MEK at 20 C. leading to a clear solution. Similarly, 12 g MDEA, 4 g Dabco K15, 16 g decanol 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.

3.4 Example 4

(14) In a polypropylene container, 48 g M200 were dissolved under stirring in 220 g MEK at 20 C. leading to a clear solution. Similarly, 12 g MDEA, 4 g Dabco K15, 8 g decanol 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.

3.5 Example 5

(15) In a polypropylene container, 48 g M200 were dissolved under stirring in 220 g MEK at 20 C. leading to a clear solution. Similarly, 12 g MDEA, 4 g Dabco K15, 16 g nonanol 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.

3.6 Example 6

(16) In a polypropylene container, 48 g M200 were dissolved under stirring in 220 g MEK at 20 C. leading to a clear solution. 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.

3.7 Example 7

(17) In a polypropylene container, 48 g M200 were dissolved under stirring in 220 g MEK at 20 C. leading to a clear solution. Similarly, 12 g MDEA, 4 g Dabco K15, 8 g ethanol 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.

3.8 Example 8

(18) In a polypropylene container, 48 g M200 were dissolved under stirring in 220 g MEK at 20 C. leading to a clear solution. Similarly, 12 g MDEA, 4 g Dabco K15, 4 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.

3.9 Example 9

(19) In a polypropylene container, 48 g M200 were dissolved under stirring in 220 g MEK at 20 C. leading to a clear solution. Similarly, 12 g MDEA, 4 g Dabco K15, 2 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.

3.10 Example 10

(20) In a polypropylene container, 48 g M200 were dissolved under stirring in 220 g MEK at 20 C. leading to a clear solution. Similarly, 12 g MDEA, 4 g Dabco K15, 1 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.

3.11 Example 11

(21) In a polypropylene container, 48 g M200 were dissolved under stirring in 220 g MEK at 20 C. leading to a clear solution. Similarly, 12 g MDEA, 4 g Dabco K15, 4 g decanol 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.

3.12 Example 12

(22) In a polypropylene container, 48 g M200 were dissolved under stirring in 220 g MEK at 20 C. leading to a clear solution. Similarly, 12 g MDEA, 4 g Dabco K15, 2 g decanol 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.

3.13. Example 13

(23) 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. 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 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.

3.14. Example 14

(24) 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. 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 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.

3.15. Example 15

(25) In a polypropylene container, 1 g graphite, 1 g Exolit AP422 and 48 g M200 were stirred in 220 g MEK at 20 C. leading to a black solution with dispersed graphite and Exolit AP422. 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 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.

3.16. Example 16

(26) 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. 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 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.

3.17. Example 17

(27) 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. 12 g MDEA, 4 g Dabco K15, 12 g decanol 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.

4. Results

(28) TABLE-US-00001 TABLE 1 Results. Thermal conductivity [mW/m*K] Water Density (p = 1 bar, uptake [kg/m.sup.3] T = 10 C.) [%] Example 1 (comparative) 145 17.9 480 (MDEA, K15, H.sub.2O) Example 2 147 16.7 14 (MDEA, K15, H.sub.2O, 16 g hexadecanol) Example 3 143 16.6 15 (MDEA, K15, H.sub.2O, 16 g decanol) Example 4 17.0 (MDEA, K15, H2O, 8 g decanol) Example 5 137 16.5 (MDEA, K15, H.sub.2O, 16 g nonanol) Example 6 16.9 16 (MDEA, K15, H.sub.2O, 8 g butanol) Example 7 17.0 MDEA, K15, H.sub.2O, 8 g ethanol) Example 8 132 17.1 17 (MDEA, K15, H.sub.2O, 4 g butanol) Example 9 17.1 (MDEA, K15, H.sub.2O, 2 g butanol) Example 10 17.1 (MDEA, K15, H.sub.2O, 1 g butanol) Example 11 17.0 12 (MDEA, K15, H.sub.2O, 4 g decanol) Example 12 132 17.0 29 (MDEA, K15, H.sub.2O, 2 g decanol) Example 13 15.7 (MDEA, K15, H2O, 12 g butanol) + 1 g graphite Example 14 134 15.8 (MDEA, K15, H2O, 12 g butanol) + 1 g graphite + 1 g melamine Example 15 15.8 (MDEA, K15, H2O, 12 g butanol) + 1 g graphite + 1 g Exolit AP422 Example 16 134 16.0 (MDEA, K15, H2O, 8 g butanol) + 1 g graphite + 1 g melamine Example 17 138 15.9 (MDEA, K15, H2O, 8 g decanol) + 1 g graphite + 1 g melamine

(29) As is exemplified by the examples, a porous material according to the state of the art (example 1, comparative) has a water uptake of several hundred percent whereas the porous materials according to the present invention only have a reduced water uptake of less than 100%.

(30) Furthermore, the porous materials according to the present invention have good insulating properties as shown by the thermal conductivity.

5. Abbreviations

(31) H.sub.2O Water

(32) K15 Dabco K15 (PUR catalyst)

(33) M200 Lupranate M200 (polyisocyanate)

(34) MEK Methyl ethyl ketone

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