Porous materials based on aromatic amines

Abstract

The invention relates to a porous material comprising at least one polyfunctional isocyanate (a1) and at least one polyfunctional substituted aromatic amine (a2-s) of the general formula (I): ##STR00001##
where R.sup.1 and R.sup.2 are selected 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 selected from among hydrogen, a primary amino group and a linear or branched alkyl group having from 1 to 12 carbon atoms, where at least one of Q.sup.1, Q.sup.3 and Q.sup.5 and at least one of Q.sup.1′, Q.sup.3′ and Q.sup.5′ is a primary amino group and the compound has at least one linear or branched alkyl group having from 1 to 12 carbon atoms in the α position relative to at least one primary amino group bound to the aromatic ring in formula (I).

Claims

1. A porous material comprising, in reacted form: (a1) a polyfunctional isocyanate; and (a2) a polyfunctional substituted aromatic amine (a2-s) of formula (I): ##STR00004## wherein: R.sup.1 and R.sup.2 are each hydrogen; and Q.sup.1 and Q.sup.1′ are each a primary amino group; Q.sup.3, Q.sup.3′, Q.sup.5, Q.sup.5′ are each hydrogen; and Q.sup.2, Q.sup.2′, Q.sup.4 and Q.sup.4′ are each independently a linear or branched alkyl group comprising from 1 to 12 carbon atoms, and wherein the component (a2) optionally comprises a further polyfunctional amine which is different from the amine (a2-s) of formula (I) and is selected from the group consisting of a polyfunctional aliphatic amine (a2-a) and polyfunctional aromatic amine (a2-u), wherein the polyfunctional aromatic amine (a2-u) is selected from the group consisting of isomers and derivatives of diaminodiphenylmethane and isomers and derivatives of toluenediamine, wherein the polyfunctional aliphatic amine (a2-a) is a polyalkylenepolyamine, wherein the porous material is in the form of a xerogel and has a volume-weighted average pore diameter of at least 1.4 μm and at most 4 μm, wherein the porous material comprises, in reacted form, from 35 to 65% by weight of the isocyanate component (a1) and from 35 to 65% by weight of the amine component (a2), where a sum of the % by weight of the components (a1) and (a2) is 100% by weight, wherein the porous material has a porosity of at least 85% by volume and a pore volume of 5.5 to 6.3 mL/g, wherein the porous material has a density of 100 to 200 g/L, and wherein the component (a1) is at least one polyfunctional isocyanate selected from the group consisting of diphenylmethane 4,4′-diisocyanate, diphenylmethane 2,4′-diisocyanate, diphenylmethane 2,2′-diisocyanate, and oligomeric diphenylmethane diisocyanate.

2. The porous material of claim 1, wherein the alkyl groups of the polyfunctional aromatic amine (a2-s) of formula (I) are selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, and tert-butyl.

3. The porous material of claim 1, wherein the polyfunctional aromatic amine (a2-u) is selected from the group consisting of a 4,4′-diaminodiphenylmethane, a 2,4′-diaminodiphenylmethane, a 2,2′-diaminodiphenylmethane, and an oligomeric diaminodiphenylmethane.

4. The porous material of claim 1, wherein the polyfunctional aromatic amine (a2-u) has a functionality of at least 2.1, and is an oligomeric diaminodiphenylmethane.

5. The porous material of claim 1, wherein the polyfunctional aromatic amine (a2-s) of formula (I) is a 3,3′,5,5′-tetraethyl-4,4′-diaminodiphenylmethane.

6. A process for producing the porous material of claim 1, the process comprising: (a) reacting the components (a1) and (a2) in the presence of a solvent (C), to form a gel; and then (b) drying the gel, to obtain the porous material.

7. The process of claim 6, wherein the drying (b) is carried out by converting a liquid comprised in the gel into a gas at a temperature and a pressure below a critical temperature and a critical pressure of the liquid.

8. The process of claim 6, wherein the drying (b) is carried out under supercritical conditions.

9. A porous material, obtained by the process of claim 6.

10. A process for thermally insulating a material, the process comprising incorporating the porous material of claim 1 into an insulation material.

11. A process for thermally insulating a vacuum insulation panel, the process comprising: incorporating the porous material of claim 1 into a vacuum insulation panel.

Description

EXAMPLES

(1) The determination of the pore volume in ml per g of sample and the average pore size of the materials was carried out by means of mercury porosimetry in accordance with DIN 66133 (1993) at room temperature. The average pore size is, for the purposes of the present invention, the average pore diameter. The determination of the volume-weighted average pore diameter is carried out mathematically from the pore size distribution determined in accordance with the abovementioned standard.

(2) The porosity in the unit % by volume was calculated according to the formula P=(V.sub.i/(V.sub.i+V.sub.s))*100% by volume, where P is the porosity, V.sub.i is the Hg intrusion volume in accordance with DIN 66133 in ml/g and V.sub.s is the specific volume in ml/g of the test specimen.

(3) The density ρ of the porous material in the unit g/ml was calculated according to the formula ρ=1/(V.sub.i+V.sub.s). As specific volume, the value 1/V.sub.s=1.38 g/ml was used. This value can be determined by He pycnometry.

(4) The following compounds were used:

(5) a1-1: oligomeric MDI (Lupranat® M200) having an NCO content of 30.9 g per 100 g in 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.

(6) a1-2: oligomeric MDI (Lupranat® M50) having an NCO content of 31.5 g per 100 g in accordance with ASTM D-5155-96 A, a functionality in the range from 2.8 to 2.9 and a viscosity of 550 mPa.Math.s at 25° C. in accordance with DIN 53018.

(7) a2-1: Tetraethyl-4,4′-diaminodiphenylmethane

(8) a2-2: Tetraisopropyl-4,4′-diaminodiphenylmethane

(9) a2-3: 3,3′-Diisopropyl-5,5′-dimethyl-4,4′-diaminodiphenylmethane

(10) a2-4: 4,4′-Diaminodiphenylmethane

Example 1

(11) 1.6 g of the compound a1-1 were dissolved with stirring in 10.5 g of acetone at 20° C. in a glass beaker. 1.6 g of tetraethyl-4,4′-diaminodiphenylmethane (a2-1) were dissolved in 11 g of acetone in a second glass beaker. The two solutions from step (a) were mixed. This gave a clear, low-viscosity mixture. The mixture was allowed to stand at room temperature for 24 hours to effect curing. The gel was subsequently taken from the glass beaker and the liquid (acetone) was removed by drying at 20° C. for 7 days.

(12) The material obtained had an average pore diameter of 4 μm. The porosity was 89% by volume with a corresponding density of 135 g/l.

Example 2

(13) 1.6 g of the compound a1-2 were dissolved with stirring in 10.5 g of acetone at 20° C. in a glass beaker. 1.6 g of 3,3′-diisopropyl-5,5′-dimethyl-4,4′-diaminodiphenylmethane (a2-3) were dissolved in 11 g of acetone in a second glass beaker. The two solutions from step (a) were mixed. This gave a clear, low-viscosity mixture. The mixture was allowed to stand at room temperature for 24 hours to effect curing. The gel was subsequently taken from the glass beaker and the liquid (acetone) was removed by drying at 20° C. for 7 days.

(14) The material obtained had a pore volume of 5.6 ml/g and an average pore diameter of 3 μm. The porosity was 89% by volume with a corresponding density of 155 g/l.

Example 3

(15) 1.4 g of the compound a1-1 were dissolved with stirring in 10.5 g of acetone at 20° C. in a glass beaker. 1.7 g of tetraisopropyl-4,4′-diaminodiphenylmethane (a2-2) were dissolved in 11 g of acetone in a second glass beaker. The two solutions from step (a) were mixed. This gave a clear, low-viscosity mixture. The mixture was allowed to stand at room temperature for 24 hours to effect curing. The gel was subsequently taken from the glass beaker and the liquid (acetone) was removed by drying at 20° C. for 7 days.

(16) The material obtained had a pore volume of 6.3 ml/g and an average pore diameter of 2 μm. The porosity was 85% by volume with a corresponding density of 143 g/l.

Example 4

(17) 1.4 g of the compound a1-2 were dissolved with stirring in 10.5 g of acetone at 20° C. in a glass beaker. 1.7 g of tetraisopropyl-4,4′-diaminodiphenylmethane (a2-2) were dissolved in 11 g of acetone in a second glass beaker. The two solutions from step (a) were mixed. This gave a clear, low-viscosity mixture. The mixture was allowed to stand at room temperature for 24 hours to effect curing. The gel was subsequently taken from the glass beaker and the liquid (acetone) was removed by drying at 20° C. for 7 days.

(18) The material obtained had a pore volume of 5.5 ml/g and an average pore diameter of 1.5 μm. The porosity was 85% by volume with a corresponding density of 160 g/l.

Example 5C

(19) 1.9 g of the compound a1-1 were dissolved with stirring in 10.5 g of acetone at 20° C. in a glass beaker. 1.3 g of 4,4′-diaminodiphenylmethane (a2-4) were dissolved in 11 g of acetone in a second glass beaker. The two solutions from step (a) were mixed. This gave a clear, low-viscosity mixture. The mixture was allowed to stand at room temperature for 24 hours to effect curing. The gel was subsequently taken from the glass beaker and the liquid (acetone) was removed by drying at 20° C. for 7 days.

(20) The material obtained had a pore volume of 5.1 ml/g and an average pore diameter of 2.9 μm. The porosity was 87% by volume with a corresponding density of 170 g/l.

Example 6C

(21) 2 g of the compound a1-2 were dissolved with stirring in 10.5 g of acetone at 20° C. in a glass beaker. 1.3 g of 4,4′-diaminodiphenylmethane (a2-4) were dissolved in 11 g of acetone in a second glass beaker. The two solutions from step (a) were mixed. This gave a clear, low-viscosity mixture. The mixture was allowed to stand at room temperature for 24 hours to effect curing. The gel was subsequently taken from the glass beaker and the liquid (acetone) was removed by drying at 20° C. for 7 days.

(22) The material obtained had a pore volume of 3.1 ml/g and an average pore diameter of 1.5 μm. The porosity was 81% by volume with a corresponding density of 260 g/l.

(23) The use of the substituted polyfunctional aromatic amines according to the invention leads to porous materials which, in particular, have a reduced density at a comparable porosity.