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) at least comprising an isocyanate composition (A*) comprising a polymeric polyfunctional isocyanate as component (ai), a monomeric polyfunctional isocyanate as component (aii), at least one catalyst as component (ac), wherein composition (A) is substantially free of aromatic amines, and a solvent (B), reacting the components in the composition (A) obtaining an organic 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.

Claims

1: A process for preparing a porous material, comprising: providing a mixture (I), the mixture (I) comprising (i) a composition (A) comprising an isocyanate composition (A*) comprising a polymeric polyfunctional isocyanate as component (ai), and a monomeric polyfunctional isocyanate as component (aii), and at least one catalyst as component (ac), and (ii) a solvent (B); b) reacting the components in the composition (A) to obtain an organic gel; and c) drying the obtained gel, wherein the composition (A) is substantially free of aromatic amines, and the components (ai), (aii) and (ac) of the composition (A) are provided separately from one another, each in a suitable partial amount of the solvent (B).

2: The process according to claim 1, wherein the isocyanate composition (A*) comprises the component (ai) in an amount of from 84 to 27% by weight and the component (aii) in an amount of from 16 to 73% by weight based on a total weight of the isocyanate composition (A*).

3: The process according to claim 1, wherein the component (ai) is selected from polymeric polyfunctional isocyanates based on diphenylmethane diisocyanate (MDI), and the component (aii) is selected from monomeric diphenylmethane diisocyanate (MDI).

4: The process according to claim 1, wherein the component (aii) comprises a mixture of 2,2-diphenylmethane diisocyanate, 2,4-diphenylmethane diisocyanate and 4,4-diphenylmethane diisocyanate.

5: The process according to claim 1, wherein the composition (A) comprises less than 1% by weight of water.

6: The process according to claim 1, wherein the composition (A) comprises from 80 to 99.9% by weight of the isocyanate composition (A*), and from 0.1 to 20% by weight of the component (ac), based on the total weight of the composition (A), where the % by weight of the components of the composition (A) add up to 100% by weight.

7: The process according to claim 1, wherein the at least one catalyst component (ac) comprises a catalyst 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 salts; onium hydroxides and alkali metal and alkaline earth metal hydroxides; alkoxides; and carboxylates.

8: The process according to claim 7, wherein the catalyst catalyzes trimerization to form isocyanurate groups.

9: The process according to claim 8, wherein the at least one catalyst component (ac) comprises the catalyst catalyzing the trimerization to form isocyanurate groups and an amine catalyst.

10: The process according to claim 1, wherein the at least one catalyst component (ac) comprises at least one metal salt of a carboxylic acid.

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

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

13: A porous material, wherein the porous material is obtained by the process according to claim 1.

14: The porous materials according to claim 13, wherein the porous material is comprised in thermal insulation material or vacuum insulation panels.

15: An interior or exterior thermal insulation system, comprising the porous material according to claim 14.

Description

EXAMPLES

1. Methods

1.1 Determination of Thermal Conductivity

[0208] The thermal conductivity was measured according to DIN EN 12667 with a heat flow meter from Hesto (Lambda Control A50).

1.2 Solvent Extraction with Supercritical Carbon Dioxide

[0209] 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.

2. Materials

[0210] M200: 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)

[0211] Lupranat MI: monomeric MDI (Lupranat MI) having an NCO content of 33.5 g per 100 g accordance with ASTM D-5155-96 A, a functionality in the region of two and a viscosity of 12 mPa.Math.s at 25 C. in accordance with DIN 53018 (hereafter MI)

[0212] Lupranat ME: monomeric MDI (Lupranat ME) having an NCO content of 33.5 g per 100 g accordance with ASTM D-5155-96 A, a functionality in the region of two and a viscosity of 5 mPa.Math.s at 42 C. in accordance with DIN 53018 (hereafter ME)

[0213] Catalysts: Dabco K15 (potassium ethylhexanoate dissolved in diethylene glycol (85%)) [0214] Dabco TMR3 (Air Products; 42% trimethylhydroxylpropylammonium formiate+40% dipropylene glycole +10% formic acid) [0215] Niax A1 (Momentive) (also available as Lupragen N206 (BASF), 70% bis-(dimethylaminoethyl)ether in dipropylene glycol)

[0216] Solvent: Acetone [0217] Methyl ethyl ketone (MEK) [0218] Diethyl ketone (DEK) [0219] Toluene

3. EXAMPLES

3.1 Example 1

[0220] In a polypropylene container, 56 g M200 were dissolved under stirring in 220 g MEK at 20 C. leading to a clear solution. Similarly, 2 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 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.

[0221] The gel-monolith was removed from the container and transferred to an autoclave. The autoclave was filled with >99 vol % of acetone, to fully cover the gel and then the lid closed. This prevents the gel from shrinking due to evaporating solvent, before the monolith gets in contact with sc. CO.sub.2. The gel was dried in a supercritical CO.sub.2 stream for 24 h. The pressure in the vessel was between 115-120 bar; the temperature was between 40-60 C. At the end of the drying step, the pressure of the system was reduced to 1 bar over 45 min at a temperature of 40 C. The autoclave was opened ant the destroyed monolith was removed. The internal tension resulted in a complete destruction of the material.

3.2 Example 2

[0222] In a polypropylene container, 39.2 g M200 and 16.8 g MI were dissolved under stirring in 220 g MEK at 20 C. leading to a clear solution. Similarly, 2 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 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.

[0223] The gel-monolith was removed from the container and transferred to an autoclave. The autoclave was filled with >99 vol % of acetone, to fully cover the gel and then the lid closed. This prevents the gel from shrinking due to evaporating solvent, before the monolith gets in contact with sc. CO.sub.2. The gel was dried in a supercritical CO.sub.2 stream for 24 h. The pressure in the vessel was between 115-120 bar; the temperature was between 40-60 C. At the end of the drying step, the pressure of the system was reduced to 1 bar over 45 min at a temperature of 40 C. The autoclave was opened ant the monolith was removed. The thermal conductivity was measured according to DIN EN 12667 with a plate apparatuses from Hesto (Lambda Control A50). The thermal conductivity was 18.4 mW/m*K at 10 C. The density was 202 kg/m.sup.3.

3.3 Example 3

[0224] In a polypropylene container, 28 g M200 and 28 g MI were dissolved under stirring in 220 g MEK at 20 C. leading to a clear solution. Similarly, 2 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 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.

[0225] The gel-monolith was removed from the container and transferred to an autoclave. The autoclave was filled with >99 vol % of acetone, to fully cover the gel and then the lid closed. This prevents the gel from shrinking due to evaporating solvent, before the monolith gets in contact with sc. CO.sub.2. The gel was dried in a supercritical CO.sub.2 stream for 24 h. The pressure in the vessel was between 115-120 bar; the temperature was between 40-60 C. At the end of the drying step, the pressure of the system was reduced to 1 bar over 45 min at a temperature of 40 C. The autoclave was opened ant the monolith was removed. The thermal conductivity was measured according to DIN EN 12667 with a plate apparatuses from Hesto (Lambda Control A50). The thermal conductivity was 18.9 mW/m*K at 10 C. The density was 189 kg/m.sup.3.

3.4 Example 4

[0226] In a polypropylene container, 39.2 g M200 and 8.4 g MI and 8.4 g ME were dissolved under stirring in 220 g Acetone at 20 C. leading to a clear solution. Similarly, 2 g Dabco K15 were dissolved in 220 g Acetone 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.

[0227] The gel-monolith was removed from the container and transferred to an autoclave. The autoclave was filled with >99 vol % of acetone, to fully cover the gel and then the lid closed. This prevents the gel from shrinking due to evaporating solvent, before the monolith gets in contact with sc. CO.sub.2. The gel was dried in a supercritical CO.sub.2 stream for 24 h. The pressure in the vessel was between 115-120 bar; the temperature was between 40-60 C. At the end of the drying step, the pressure of the system was reduced to 1 bar over 45 min at a temperature of 40 C. The autoclave was opened ant the monolith was removed. The thermal conductivity was measured according to DIN EN 12667 with a plate apparatuses from Hesto (Lambda Control A50). The thermal conductivity was 21.2 mW/m*K at 10 C. The density was 286 kg/m.sup.3.

3.5 Example 5

[0228] In a polypropylene container, 39.2 g M200 and 8.4 g MI and 8.4 g ME were dissolved under stirring in 220 g MEK at 20 C. leading to a clear solution. Similarly, 2 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 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.

[0229] The gel-monolith was removed from the container and transferred to an autoclave. The autoclave was filled with >99 vol % of acetone, to fully cover the gel and then the lid closed. This prevents the gel from shrinking due to evaporating solvent, before the monolith gets in contact with sc. CO.sub.2. The gel was dried in a supercritical CO.sub.2 stream for 24 h. The pressure in the vessel was between 115-120 bar; the temperature was between 40-60 C. At the end of the drying step, the pressure of the system was reduced to 1 bar over 45 min at a temperature of 40 C. The autoclave was opened ant the monolith was removed. The thermal conductivity was measured according to DIN EN 12667 with a plate apparatuses from Hesto (Lambda Control A50). The thermal conductivity was 19.8 mW/m*K at 10 C. The density was 229 kg/m.sup.3.

3.6 Example 6

[0230] In a polypropylene container, 39.2 g M200 and 8.4 g MI and 8.4 g ME were dissolved under stirring in 220 g DEK at 20 C. leading to a clear solution. Similarly, 2 g Dabco K15 were dissolved in 220 g DEK 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.

[0231] The gel-monolith was removed from the container and transferred to an autoclave. The autoclave was filled with >99 vol % of acetone, to fully cover the gel and then the lid closed. This prevents the gel from shrinking due to evaporating solvent, before the monolith gets in contact with sc. CO.sub.2. The gel was dried in a supercritical CO.sub.2 stream for 24 h. The pressure in the vessel was between 115-120 bar; the temperature was between 40-60 C. At the end of the drying step, the pressure of the system was reduced to 1 bar over 45 min at a temperature of 40 C. The autoclave was opened ant the monolith was removed. The thermal conductivity was measured according to DIN EN 12667 with a plate apparatuses from Hesto (Lambda Control A50). The thermal conductivity was 17.0 mW/m*K at 10 C. The density was 212 kg/m.sup.3.

3.7 Example 7

[0232] In a polypropylene container, 39.2 g M200 and 18.8 g ME were dissolved under stirring in 220 g DEK at 20 C. leading to a clear solution. Similarly, 2 g Dabco K15 were dissolved in 220 g DEK 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.

[0233] The gel-monolith was removed from the container and transferred to an autoclave. The autoclave was filled with >99 vol % of acetone, to fully cover the gel and then the lid closed. This prevents the gel from shrinking due to evaporating solvent, before the monolith gets in contact with sc. CO.sub.2. The gel was dried in a supercritical CO.sub.2 stream for 24 h. The pressure in the vessel was between 115-120 bar; the temperature was between 40-60 C. At the end of the drying step, the pressure of the system was reduced to 1 bar over 45 min at a temperature of 40 C. The autoclave was opened ant the monolith was removed. The thermal conductivity was measured according to DIN EN 12667 with a plate apparatuses from Hesto (Lambda Control A50). The thermal conductivity was 16.6 mW/m*K at 10 C. The density was 242 kg/m.sup.3.

3.8 Example 8

[0234] In a polypropylene container, 39.2 g M200 and 18.8 g MI were dissolved under stirring in 220 g DEK at 20 C. leading to a clear solution. Similarly, 2 g Dabco K15 were dissolved in 220 g DEK 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.

[0235] The gel-monolith was removed from the container and transferred to an autoclave. The autoclave was filled with >99 vol % of acetone, to fully cover the gel and then the lid closed. This prevents the gel from shrinking due to evaporating solvent, before the monolith gets in contact with sc. CO.sub.2. The gel was dried in a supercritical CO.sub.2 stream for 24 h. The pressure in the vessel was between 115-120 bar; the temperature was between 40-60 C. At the end of the drying step, the pressure of the system was reduced to 1 bar over 45 min at a temperature of 40 C. The autoclave was opened ant the monolith was removed. The thermal conductivity was measured according to DIN EN 12667 with a plate apparatuses from Hesto (Lambda Control A50). The thermal conductivity was 16.7 mW/m*K at 10 C. The density was 214 kg/m.sup.3.

3.9 Example 9

[0236] In a polypropylene container, 39.2 g M200 and 8.4 g MI and 8.4 g ME were dissolved under stirring in 180 g DEK and 40 g toulene at 20 C. leading to a clear solution. Similarly, 2 g Dabco K15 were dissolved in 180 g DEK and 40 g toluene 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.

[0237] The gel-monolith was removed from the container and transferred to an autoclave. The autoclave was filled with >99 vol % of acetone, to fully cover the gel and then the lid closed. This prevents the gel from shrinking due to evaporating solvent, before the monolith gets in contact with sc. CO.sub.2. The gel was dried in a supercritical CO.sub.2 stream for 24 h. The pressure in the vessel was between 115-120 bar; the temperature was between 40-60 C. At the end of the drying step, the pressure of the system was reduced to 1 bar over 45 min at a temperature of 40 C. The autoclave was opened ant the monolith was removed. The thermal conductivity was measured according to DIN EN 12667 with a plate apparatuses from Hesto (Lambda Control A50). The thermal conductivity was 16.8 mW/m*K at 10 C. The density was 208 kg/m.sup.3.

3.10 Example 10

[0238] In a polypropylene container, 48 g M200 and 8 g ME were dissolved under stirring in 220 g DEK at 20 C. leading to a clear solution. Similarly, 2 g Dabco K15 were dissolved in 220 g DEK 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.

[0239] The gel-monolith was removed from the container and transferred to an autoclave. The autoclave was filled with >99 vol % of acetone, to fully cover the gel and then the lid closed. This prevents the gel from shrinking due to evaporating solvent, before the monolith gets in contact with sc. CO.sub.2. The gel was dried in a supercritical CO.sub.2 stream for 24 h. The pressure in the vessel was between 115-120 bar; the temperature was between 40-60 C. At the end of the drying step, the pressure of the system was reduced to 1 bar over 45 min at a temperature of 40 C. The autoclave was opened ant the monolith was removed. The thermal conductivity was measured according to DIN EN 12667 with a plate apparatuses from Hesto (Lambda Control A50). The thermal conductivity was 17.2 mW/m*K at 10 C. The density was 216 kg/m.sup.3.

3.11 Example 11

[0240] In a polypropylene container, 48 g M200 and 8 g MI were dissolved under stirring in 220 g DEK at 20 C. leading to a clear solution. Similarly, 2 g Dabco K15 were dissolved in 220 g DEK 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.

[0241] The gel-monolith was removed from the container and transferred to an autoclave. The autoclave was filled with >99 vol % of acetone, to fully cover the gel and then the lid closed. This prevents the gel from shrinking due to evaporating solvent, before the monolith gets in contact with sc. CO.sub.2. The gel was dried in a supercritical CO.sub.2 stream for 24 h. The pressure in the vessel was between 115-120 bar; the temperature was between 40-60 C. At the end of the drying step, the pressure of the system was reduced to 1 bar over 45 min at a temperature of 40 C. The autoclave was opened ant the monolith was removed. The thermal conductivity was measured according to DIN EN 12667 with a plate apparatuses from Hesto (Lambda Control A50). The thermal conductivity was 17.4 mW/m*K at 10 C. The density was 243 kg/m.sup.3.

4. Abbreviations

[0242] H.sub.2O Water

[0243] K15 Dabco K15 (PUR catalyst)

[0244] M200 Lupranate M200 (polyisocyanate)

[0245] MI Lupranat MI (monomeric isocyanate)

[0246] ME Lupranat ME (monomeric isocyanate)

[0247] DEK Diethyl ketone

[0248] MEK Methyl ethyl ketone

[0249] MDEA 4,4-Methylene-bis(2,6-diethylaniline)