HEAT INSULATION MATERIAL BASED ON AEROGEL

Abstract

A heat insulation material is provided that is produced by drying a fibrous matrix impregnated with a solution of pseudo-peptides of formula (I), wherein: R is a side-chain of a natural or synthetic amino acid , R1 is either a linear or branched (C.sub.1-C.sub.3)alkyl group, or a linear or branched (C.sub.1-C.sub.3)alcoxy group, or an aryl group, or an aryl(C.sub.1-C.sub.3)alkyl group, or an aryloxy group, or a saturated or unsaturated heterocycle, n=1 or 2, and A is an aromatic or heteroaromatic group with at least one cycle.

Claims

1. A thermal insulating material obtained by drying a fibrous matrix impregnated with a solution of pseudopeptides of formula (I), ##STR00007## in which R represents a side chain of a natural or synthetic amino acid: R.sub.1 represents either a linear or branched (C.sub.1-C.sub.8)alkyl group, or a linear or branched (C.sub.1-C.sub.8)alkoxy group, or an aryl group, or an aryl(C.sub.1-C.sub.4)alkyl group, or an aryloxy group, or a saturated or unsaturated heterocycle, n=1 or 2: and A represents an aromatic or heteroaromatic group with one or more rings, said fibrous matrix having low thermal conductivity of less than 0.05 W/m/K and a density of less than 50 kg/m.sup.3.

2. The thermal insulating material according to claim 1, characterized in that the pseudopeptide of formula (I) is selected from those in which the group ##STR00008## represents either a group ##STR00009## or a group ##STR00010##

3. The thermal insulating material according to claim 1, characterized in that the pseudopeptide of formula (I) is selected from those in which R represents either —CH.sub.2Ph, or —CH(CH.sub.3).sub.3 or —CH(CH.sub.3).sub.2 and R.sub.1 represents either PhCH.sub.2OCO— or CH.sub.2=CH—CH.sub.2OCO—.

4. The thermal insulating material according to claim 1, characterized in that said fibrous matrix is a matrix of plant, animal, mineral origin, of natural or synthetic polymers, or a matrix obtained by mixtures thereof.

5. The thermal insulating material according to claim 4, characterized in that said matrix is in particular selected from the group comprising a fibreboard, a blanket of wood fibres, a cotton, wool, mineral wool, polystyrene, polyurethane, polyisocyanate or polyisocyanurate matrix.

6. The thermal insulating material according to claim 1, characterized in that said material is obtained by drying a fibreboard impregnated with a solution of pseudopeptides of formula (Ia) or a blanket of wood fibres impregnated with a solution of pseudopeptides of formula (Ia). ##STR00011##

7. A method for preparing a thermal insulating material according to claim 1, wherein said method comprises the following stages: (i) preparing a liquid solution of pseudopeptides of formula (I), in particular of formula (Ia), in a solvent; (ii) bringing a matrix as described according to claim 1 into contact with a solution obtained in stage (i) until said matrix is completely impregnated with said solution and reaches its maximum capacity for absorbing said solution; (iii) forming an organogel/matrix complex by cooling; and (iv) extracting the solvent contained in said organogel/matrix complex in order to obtain the aforesaid thermal insulating material.

8. A thermal insulating material capable of being obtained by a method according to claim 7.

9. Use of a solution of pseudopeptides of formula (I) as described according to claim 1, in order to improve the hydrophobicity of a fibrous matrix.

Description

EXAMPLE 1

Preparation of a Material According to the Invention

[0041] This example illustrates the preparation of a material of the invention obtained by drying a fibreboard impregnated with a solution of pseudopeptides of formula (Ia).

1. Materials and Methods

1.1. Characteristic of the Fibreboard

[0042] The fibreboard used in the example has a density of 43 kg/m.sup.3 and is in the form of square samples of 5×5 cm on each side.

1.2. Preparation of the Solution of Pseudopeptides of Formula (Ia)

[0043] A solution of pseudopeptides of formula (Ia) at 14.9% in 3-pentanol is prepared as follows:

[0044] 2.14 g of the compound of formula (Ia) were dissolved hot in 15 mL of 3-pentanol in order to obtain a solution of the compound of formula (Ia) at 14.9% by weight. Solubilization is carried out for 2 minutes under stirring in a flask placed in a microwave oven offering the possibility of open reactor working. The working temperature of the microwave oven is set to 100° C. under a maximum power of 150 Watts. The flask is equipped with a water condensing system in order to condense the solvent vapours and to maintain the concentration of the solution.

[0045] The solution is maintained at a temperature greater than the sol-gel transition temperature, i.e. approximately 100° C. for a solution at 14.9%

1.3. Preparation of the “Fibreboard/Organogel” Composite

[0046] The fibreboard is placed in a stainless steel mould of the same dimension, which has been heated beforehand in order to avoid any thermal shock. The solution of the compound of formula (Ia) in 3-pentanol maintained at 100° C. is then poured onto the fibreboard. The mixture is cooled to ambient temperature until gelation of the gel. The “fibreboard/organogel” composite obtained is then extracted from the mould.

1.4. Drying the “Fibreboard/Organogel” Composite System

[0047] The composite obtained is dried according to the supercritical CO.sub.2 drying process described in application WO2010/133798.

[0048] Said process is implemented in an autoclave (8 cm high, 100 ml volume) composed of a hollow, double-walled cylinder and two detachable ends composed of sintered metal allowing the passage of fluids.

[0049] The “fibreboard/organogel” composite is placed in an autoclave having a bed of beads covered with 0.5 g of 3-pentanol and maintained at 15° C. After closing the autoclave, the CO.sub.2 previously cooled to 4° C. is introduced into the reactor under a pressure of 50 bar (5×10.sup.6Pa). The pressure is then raised to 90 bar (9×10.sup.6Pa) by injecting CO.sub.2 using a diaphragm pump. The pressure of the first separator is set to 50 bar (5×10.sup.6Pa) and that of the second separator to 20 bar (2×10.sup.6Pa). The CO.sub.2 flow rate is set to 400 g/h. The temperature of the separation elements is maintained at 20° C. during the entire drying process.

[0050] The temperature of the autoclave is then raised to 45° C. so as to cause the CO.sub.2/3-pentanol system to pass to supercritical phase. After 20 minutes, the outlet valves of the autoclave and of the last separator are opened.

[0051] The continuous extraction of the 3-pentanol for 4h with a CO.sub.2 flow rate of 400 g/h makes it possible to obtain the expected “fibreboard/aerogel” composite.

2. Characteristics of the “Fibreboard/Aerogel” Product

[0052] The final “fibreboard/aerogel” product obtained has a density of 183 Kg/m.sup.3.

[0053] The thermal conductivity of the final product is measured by the three layers method (Y. Jannot, G. Payet, A. Degiovanni, IJHMT 2009, 52, 1105-1111), finished by a centered hot plate measurement (Y. Jannot, V. Felix, A. Degiovanni, Measurement Science and Technology 2010, 21, No. 35106).

[0054] The thermal conductivity of said final product measured at ambient temperature of approximately 25° C. is 0.026 W/m/K.

[0055] Said final product has a better mechanical strength compared to the organic aerogel alone described in application WO2010/133798 and to the fibreboard.

[0056] The density of the final product, which is approximately 183 kg/m.sup.3, is clearly greater than that of the organic aerogel alone described in application WO2010/133798 (2.83 kg/m.sup.3) and that of the fibreboard (43 kg/m.sup.3).

[0057] Moreover, said product has a better hydrophobicity than the fibreboard and close to that of the aerogel described in application WO2010/133798.

EXAMPLE 2

Preparation of a Material According to the Invention

[0058] This example illustrates the preparation of a material according to the invention obtained by drying a fibreboard impregnated with a solution of pseudopeptides of formula (Ia).

1. Materials and Methods

1.1. Characteristic of the Fibreboard

[0059] The fibreboard used in the example has a density of 43 kg/m.sup.3 and is in the form of square samples of 5×5 cm on each side.

1.2. Preparation of the Solution of Pseudopeptides of Formula (Ia)

[0060] A solution of pseudopeptides of formula (Ia) at 14.9% in 3-pentanol is prepared as follows:

[0061] 2.14 g of the compound of formula (Ia) were dissolved hot in 15 mL of 3-pentanol in order to obtain a solution of the compound of formula (Ia) at 14.9% by weight. Solubilization is carried out for 2 minutes under stirring in a flask placed in a microwave oven offering the possibility of working in an open reactor. The working temperature of the microwave oven is set to 100° C. under a maximum power of 150 Watts. The flask is equipped with a water condensing system in order to condense the solvent vapours and to maintain the concentration of the solution.

[0062] The solution is maintained at a temperature greater than the sol-gel transition temperature, i.e. approximately 100° C. for a solution at 14.9%.

1.3. Preparation of the “Fibreboard/Organogel” Composite

[0063] The fibreboard is placed in a stainless steel mould of the same dimension, which has been heated beforehand in order to avoid any thermal shock. The solution of the compound of formula (Ia) in 3-pentanol maintained at 100° C. is then poured onto the fibreboard. The mixture is cooled to ambient temperature until gelation of the gel. The “fibreboard/organogel” composite obtained is then extracted from the mould.

1.4. Drying the “Fibreboard/Organogel” Composite System

[0064] The composite obtained is dried according to the supercritical CO.sub.2 drying process described in application WO2010/133798.

[0065] Said process is implemented in an autoclave (8 cm high, 100 ml volume) composed of a hollow, double-walled cylinder and two detachable ends composed of sintered metal allowing the passage of fluids.

[0066] The “fibreboard/organogel” composite is placed in an autoclave having a bed of beads covered with 3.5 g of 3-pentanol and maintained at 15° C. After closing the autoclave, the CO.sub.2 previously cooled to 4° C. is introduced into the reactor under a pressure of 50 bar (5×10.sup.6Pa). The pressure is then raised to 90 bar (9×10.sup.6Pa) by injecting CO.sub.2 using a diaphragm pump. The pressure of the first separator is set to 50 bar (5×10.sup.6Pa) and that of the second separator to 20 bar (2×10.sup.6Pa). The CO.sub.2 flow rate is set to 400 g/h. The temperature of the separation elements is maintained at 20° C. during the entire drying process.

[0067] The temperature of the autoclave is then raised to 45° C. so as to cause the CO.sub.2/3-pentanol system to pass to supercritical phase. After 20 minutes, the outlet valves of the autoclave and of the last separator are opened.

[0068] The continuous extraction of the 3-pentanol for 4h with a CO.sub.2 flow rate of 400 g/h makes it possible to obtain the expected “fibreboard/aerogel” composite.

2. Characteristics of the “Fibreboard/Aerogel” Product

[0069] The final “fibreboard/aerogel” product obtained has a density of 183 Kg/m.sup.3.

[0070] The thermal conductivity of the final product is measured by the three layers method (Y. Jannot, G. Payet, A. Degiovanni, IJHMT 2009, 52, 1105-1111), finished by a centred hot plate measurement (Y. Jannot, V. Felix, A. Degiovanni, Measurement Science and Technology 2010, 21, No. 35106).

[0071] The thermal conductivity of said final product measured at ambient temperature of approximately 25° C. is 0.026 W/m/K.

[0072] Said final product has a better mechanical strength compared to the organic aerogel alone described in application WO2010/133798 and to the fibreboard.

[0073] The density of the final product, which is approximately 183 kg/m.sup.3, is clearly greater than that of the organic aerogel alone described in application WO2010/133798 (2.83 kg/m.sup.3) and that of the fibreboard (43 kg/m.sup.3). Moreover, said product has a better hydrophobicity than the fibreboard and close to that of the aerogel described in application WO2010/133798.

EXAMPLE 3

Preparation of a Material According to the Invention

[0074] This example illustrates the preparation of a material of the invention obtained by drying a blanket of untreated wood fibres impregnated with a solution of pseudopeptides of formula (Ia).

1. Materials and Methods

1.1. Characteristic of the Untreated Wood Fibres

[0075] The wood fibres used in the example are fine and untreated from the industrial defibration of wood.

1.2. Preparation of the Solution of Pseudopeptides of Formula (Ia)

[0076] A solution of pseudopeptides of formula (Ia) at 13% in 3-pentanol is prepared as follows:

[0077] 1.23 g of the compound of formula (Ia) were dissolved hot in 10 mL of 3-pentanol in order to obtain a solution of the compound of formula (Ia) at 13% by weight. Solubilization is carried out for 2 minutes under stirring in a flask placed in a microwave oven offering the possibility of working in an open reactor. The working temperature of the microwave oven is set to 100° C. under a maximum power of 150 Watts. The flask is equipped with a water condensing system in order to condense the solvent vapours and to maintain the concentration of the solution.

[0078] The solution is maintained at a temperature greater than the sol-gel transition temperature, i.e. approximately 100° C. for a solution at 13%.

1.3. Preparation of the “Blanket of Wood Fibres/Organogel” Composite

[0079] The untreated wood fibres are placed and packed into an aluminium mould of dimensions 45 mm×45 mm×5 mm, which has been heated beforehand in order to avoid any thermal shock. The solution of the compound of formula (Ia) in 3-pentanol maintained at 100° C. is then injected into the mould, thus impregnating the blanket of wood fibres. The mixture is cooled to ambient temperature until gelation of the system. The “blanket of wood fibres/organogel” composite obtained is then extracted from the mould.

1.4. Drying the “Blanket of Wood Fibres/Organogel” Composite System

[0080] The composite obtained is dried according to the supercritical CO.sub.2 drying process described in application WO2010/133798.

[0081] Said process is implemented in an autoclave (8 cm high, 100 ml volume) composed of a hollow, double-walled cylinder and two detachable ends composed of sintered metal allowing the passage of fluids.

[0082] The “blanket of wood fibres/organogel” composite is placed in an autoclave having a bed of beads covered with 3.5 g of 3-pentanol and maintained at 15° C. After closing the autoclave, the CO.sub.2 previously cooled to 4° C. is introduced into the reactor under a pressure of 50 bar (5×10.sup.6Pa). The pressure is then raised to 90 bar (9×10.sup.6Pa) by injecting CO.sub.2 using a diaphragm pump. The pressure of the first separator is set to 50 bar (5×10.sup.6Pa) and that of the second separator to 20 bar (2×10.sup.6Pa). The CO.sub.2 flow rate is set to 400 g/h. The temperature of the separation elements is maintained at 20° C. during the entire drying process.

[0083] The temperature of the autoclave is then raised to 45° C. so as to cause the CO.sub.2/3-pentanol system to pass to supercritical phase. After 20 minutes, the outlet valves of the autoclave and of the last separator are opened.

[0084] The continuous extraction of the 3-pentanol for 4h with a CO.sub.2 flow rate of 400 g/h makes it possible to obtain the expected “blanket of wood fibres/aerogel” composite.

2. Characteristics of the “Blanket of Wood Fibres/Aerogel” Product

[0085] The final “blanket of wood fibres/aerogel” product obtained has a density of 143 Kg/m.sup.3.

[0086] The thermal conductivity of the final product is measured by the centred hot plate method (Y. Jannot, V. Felix, A. Degiovanni, Measurement Science and Technology 2010, 21, No. 35106).

[0087] The thermal conductivity of said final product measured at ambient temperature of approximately 25° C. is 0.025 W/m/K.