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 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 at least one compound (af) comprising phosphorous and at least one functional group which is reactive towards isocyanates. 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: reacting a composition (A) comprising a compound (af) comprising phosphorous and a functional group which is reactive towards isocyanates and a catalyst system (CS) as component (a0), in the presence of a solvent (B), to form a gel; and drying the gel to form a porous material; wherein compound (af) is present in an amount which results in a phosphorous content in the porous material in a range of from 1 to 5% by weight, wherein the compound (af) comprises at least one functional group comprising the phosphorous selected from the group consisting of a phosphonate, a phosphinate, a phosphite, a phosphonite, a phosphinite, and a phosphine oxide, the composition (A) further comprises a polyfunctional isocyanate as a component (a1), and an aromatic amine as a component (a2), optionally water as a component (a3), and optionally a further catalyst as a component (a4), the component (af) is used in an amount in the range of 1 to 5% by weight based on the sum of the weight of the components (a0) to (a4), and the catalyst system (CS) comprising a catalyst component (C1) is selected from the group consisting of an alkali metal salt of a saturated monocarboxylic acid, an alkali metal salt of an unsaturated monocarboxylic acid, an earth alkali metal salt of a saturated monocarboxylic acid, an earth alkali metal salt of an unsaturated monocarboxylic acid, an ammonium salt of a saturated monocarboxylic acid, an ammonium salt of an unsaturated monocarboxylic acid, an ionic liquid salt of a saturated monocarboxylic acid with 1 to 20 carbon atoms, and an ionic liquid salt, wherein said porous material has a water uptake of no more than 7 wt. %.

2. The process of claim 1, wherein the catalyst system (CS) further comprises a carboxylic acid as a catalyst component (C2).

3. The process of claim 2, wherein the catalyst component (C2) is at least one selected from the group consisting of a saturated monocarboxylic acid having 1 to 12 carbon atoms and an unsaturated monocarboxylic acid having 1 to 12 carbon atoms.

4. The process of claim 1, wherein the composition (A) further comprises a monool (am).

5. The process of claim 1, wherein the drying converts a liquid in the gel into the gaseous state at a temperature and a pressure below a critical temperature and a critical pressure of the liquid in the gel.

6. The process of claim 1, wherein the drying is carried out under supercritical conditions.

7. A porous material obtained by the process of claim 1.

8. A thermal insulation material or vacuum insulation panel, comprising: the porous material of claim 7.

9. An interior or exterior thermal insulation system, comprising: the porous material of claim 7.

10. An insulation of a thermal bridge, comprising: the porous material of claim 7.

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).
1.2 Solvent Extraction with Supercritical Carbon Dioxide One or several gel monoliths were placed onto sample trays in an autoclave of 25 I 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 55° 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 55° C. The autoclave was opened, and the obtained porous monoliths were removed.
1.3 Determination of Compressive Strength and E Modulus The compressive strength and the elastic modulus was measured according to DIN 53421 with 10% strain.

2. Materials

(3) 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-4,4′diaminodiphenylmethane (hereinafter “MDEA”) Catalyst: Potassium sorbate dissolved in monoethylene glycol (5, 20%) Flame redardant: Exolit OP560

3. Examples

(4) 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)

(5) 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, 2 g Ksorbate solution (5% in MEG) and 4 g Butanol—were dissolved in 220 g MEK to obtain a second solution. The solutions were combined in a rectangular container (20×20 cm×5 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. The compressive strength was determined according to DIN 53421 with 10% strain.

3.2 Example 2

(6) 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, 2 g Ksorbate solution (5% in MEG), 2 g Exolit OP560 and 4 g Butanol were dissolved in 220 g MEK to obtain a second solution. The solutions were combined in a rectangular container (20×20 cm×5 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. The compressive strength was determined according to DIN 53421 with 10% strain.

3. Example 3 (Comparative)

(7) 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, 0.28 g Ksorbate solution (20% in MEG) and 2 g Butanol were dissolved in 220 g MEK to obtain a second solution. The solutions were combined in a rectangular container (20×20 cm×5 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. The compressive strength was determined according to DIN 53421 with 10% strain.

3.2 EXAMPLE 4

(8) In a polypropylene container, 48 g M200 were stirred in 220 g MEK at 20° C. leading to a clear solvation. Similarly, 8 g MDEA, 0.28 g Ksorbate solution (20% in MEG), 1,72 g Exolit OP560 and 2 g Butanol were dissolved in 220 g MEK to obtain a second solution. The solutions were combined in a rectangular container (20×20 cm×5 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. The compressive strength was determined according to DIN 53421 with 10% strain.

4. Results

(9) TABLE-US-00001 TABLE 1 Results. Thermal conductivity [mW/m * K] Compressive Water Density (p = 1 bar, strength uptake [kg/m.sup.3] T = 10° C.) [kPa] [Wt %] Example 1 (comparative) 134 18.6 439 53 (8 g MDEA, 2 g Ksor- bate(5%), 4 g butanol) Example 2 (8 g MDEA, 116 18.0 567 7 2 g Ksorbate(5%), 4 g butanol + 2 g OP560) Example 3 (comparative) 102 19.3 273 40 (8 g MDEA, 0.28 g Ksorbate (20%), 2 g butanol) Example 4 (8 g MDEA, 139 18.9 428 0 0.28 g Ksorbate (20%), 2 g butanol + 1.72 g OP560)

5. Abbreviations

(10) H.sub.2O Water K15 Dabco K15 (PUR catalyst) M200 Lupranate M200 (polyisocyanate) MEK Methyl ethyl ketone MDEA 4,4′-Methylene-bis(2,6-diethylaniline)