Foam as adhesive for composites for thermal insulation

Abstract

The present invention relates to a process for the preparation of a composite for thermal insulation comprising at least layers (L1), (L2) and (LB), the process comprising the steps of providing layer (L1) containing from 25 to 95% by weight of aerogel and from 5 to 75% by weight of fibers and from 0 to 70% by weight of fillers and layer (L2) containing from 25 to 95% by weight of aerogel and from 5 to 75% by weight of fibers and from 0 to 70% by weight of fillers; applying a composition (C1) comprising an inorganic binder on one surface of the layer (L1) or layer (L2) or layer (L1) and (L2), and combining layer (L1) and layer (L2) in a manner that composition (C1) is located between layer (L1) and (L2), wherein composition (C1) is applied in the form of a, as well as a composite for thermal insulation comprising at least layers (L1), (L2) and layer (LB) which is located between layers (L1) and (L2) and the use of said composite for thermal insulation.

Claims

1. A process for the preparation of a composite comprising at least layers (L1), (L2) and a binder layer (LB) located between layers (L1) and (L2), the process comprising: (i) applying a foamed composition (C1) comprising an inorganic binder on one surface of the layer (L1) or layer (L2) or layer (L1) and (L2) to form the binder layer (LB), (ia) layer (L1) comprising from 25 to 95% by weight of aerogel and from 5 to 75% by weight of fibers and from 0 to 70% by weight of fillers, and (ib) layer (L2) comprising from 25 to 95% by weight of aerogel and from 5 to 75% by weight of fibers and from 0 to 70% by weight of fillers; and (ii) combining the layer (L1) and the layer (L2) in a manner that the binder layer (LB) comprising the foamed composition (C1) is located between the layer (L1) and the layer (L2); (iii) pressing to compress the binder layer (LB) between the layer (L1) and the layer (L2); and (iv) curing and/or drying the foamed composition (C1) in the binder layer (LB) between the layer (L1) and the layer (L2) to form the composite; and wherein the composite has a tensile strength that is greater than a tensile strength of a comparable laminate that is the same as the composite except made with an unfoamed composition.

2. The process according to claim 1, wherein the composite comprises further layers.

3. The process according to claim 1, further comprising: forming the foamed composition (C1) mechanically or physically.

4. The process according to claim 3, comprising: forming the foamed composition (C1) mechanically by stirring, ultrasonic foaming, by introducing mechanical energy or by blowing a gas through the composition.

5. The process according to claim 1, comprising: chemically forming the foamed composition (C1).

6. The process according to claim 5, wherein chemically forming is carried out with an agent which releases a suitable gas or by using a foaming agent.

7. The process according to claim 1, wherein the aerogel is at least one aerogel comprising silicon, aluminium and/or titanium.

8. The process according to claim 1, wherein the filler is an inorganic filler.

9. The process according to claim 1, wherein the filler is an inorganic filler selected from the group consisting of magnesium dioxide, titanium dioxide, titanium carbide, silicon carbide, iron(III) oxide, iron(II) oxide, zirconium silicate, zirconium oxide, tin oxide, manganese oxide, calcium silicate, calcium carbonate and a mixture thereof.

10. The process according to claim 1, wherein the fibers are selected from the group consisting of inorganic fibers and organic fibers.

11. The process according to claim 1, wherein the fibers are inorganic fibers selected from the group consisting of glass fibers, rock fibers, metal fibers, boron fibers, ceramic fibers, basalt fibers, and mixtures thereof.

12. The process according to claim 1, wherein the fibers are organic fibers selected from the group consisting of fibers based on polyethylene, polypropylene, polyacrylonitrile, polyamide, aramid and polyester.

13. The process according to claim 1, wherein the foamed composition (C1) comprises at least one further component selected from the group consisting of surfactants, organic and/or inorganic fibers, dispersions, infrared reflectors and/or absorbers, accelerators, retarders, thickeners, water retention agents, dispersants, rheology modifiers, antifoams, aerogel, pyrogenic silica, hollow spheres and fillers.

14. The process according to claim 1, wherein the foamed composition (C1) comprises at least one surfactant and/or Pickering stabilizers.

15. The process according to claim 1, wherein the surface on which the foamed composition (C1) is applied is treated before applying composition (C1).

16. The process according to claim 15, wherein the treatment is selected from the group consisting of plasma treatment of the surface, surface coating, removal of dust from the surface, and partially pulling out of embedded fibers from the surface.

17. The process according to claim 1, wherein the inorganic binder is at least one selected from the group consisting of alkali silicate, cement and alkali-activated aluminosilicates.

18. The process according to claim 1, wherein the binder layer (LB) has a thickness of from 0.05 to 0.4 cm before the pressing (iii).

19. The process according to claim 1, wherein the pressing (iii) compresses the binder layer (LB) to a thickness that is about 50%-95% of a thickness of the binder layer (LB) before the pressing (iii).

20. The process according to claim 1, wherein the combining forms combined layers having an initial thickness and the pressing and curing forms a composite having a thickness that is 90% or less of the initial thickness.

21. A composite, comprising at least layers (L1) and (L2) and layer (LB), wherein the composite is obtained by a process according to claim 1.

22. A process, comprising applying a composite according to claim 21 for thermal insulation.

Description

EXAMPLES

(1) I. General Description

(2) 10 mm thick aerogel blankets measuring 15 cm×15 cm were bonded using foamed glue. After applying the foamed glue on one blanket, the another blanket is put on the top. The glued blankets were then pressed to 90% of their original thickness and dried in microwave oven (power 1000 W) for 15 min.

(3) II. Preparation Examples

1. Example 1

(4) 0.5 gm of surfactant (Glucopon DK 225) and 4 gm Metakaolin (Argical® 1200 S) were added to 40 gm of potassium waterglass solution (VP 19621, IGP Dülmen GmbH). The foaming is done by stirring the above mix for 15 sec using a hand mixer. Spaceloaft A2 aerogel blanket from Aspen Aerogels were bonded using 6 gm of foamed glue using the described process.

(5) The tensile strength increased from 3.6 kPa (without foam) to 7.8 kPa (with foam).

2. Example 2

(6) The example was carried out as described in example 1 with the difference that before the application of adhesive, the dust was removed from the blanket surfaces using dust suction device.

(7) The tensile strength increased from 3.6 kPa (without foam) to 8.3 kPa (with foam).

3. Example 3

(8) The example was carried out as described in example 1 with the difference that a FMA450 aerogel blanket from Nano Tech was glued instead of Spaceloaft A2.

(9) The tensile strength increased from 3.3 kPa (without foam) to 9.1 kPa (with foam).

4. Example 4

(10) The example was carried out as described in example 3 with the difference that 3, 4 gm of foamed glue was used.

(11) The tensile strength increased from 3.1 kPa (without foam) to 6.5 kPa (with foam).

5. Example 5

(12) The example was carried out as described in example 2 with the difference that the glue was foamed without using Metakaolin in the composition.

(13) The tensile strength increased from 3.6 kPa (without foam) to 4.3 kPa (with foam).

6. Example 6

(14) The example was carried out as described in example 1 with the difference that the glue was foamed without using Metakaolin in the composition.

(15) The tensile strength increased from 3.6 kPa (without foam) to 14.7 kPa (with foam).

7. Example 7

(16) The example was carried out as described in example 6 with the difference that instead of VP 19621, K45M (from Woellner GmbH) waterglass was used.

(17) The tensile strength increased from 3.6 kPa (without foam) to 5.7 kPa (with foam). Note that the adhesion strength (adhesion of blankets) was higher than 5.7 kPa as there was cohesive failure in blanket, while without foam it was an adhesive failure.

8. Example 8

(18) The example was carried out as described in example 7 with the difference that instead of using hand mixture, the foaming is done by using the rotor stator mixer. The amount of different components were increased for big scale trial but the ratio of different componets were same as in example 7.

(19) The tensile strength increased from 3.6 kPa (without foam) to 5.5 kPa (with foam). Note that the adhesion strength (adhesion of blankets) was higher than 5.5 kPa as there was cohesive failure in blanket, while without foam it was an adhesive failure (failure within glue).

9. Example 9

(20) The example was carried out as described in example 2 with the difference that instead of VP 19621, K45M (from Woellner GmbH) waterglass was used.

(21) The tensile strength increased to 6.8 kPa (with foam). Note that the adhesion strength (adhesion of blankets) was higher than 6.8 kPa as there was cohesive failure in blanket.

10. Example 10

(22) The example was carried out as described in example 2 with the difference that the instead of potassium waterglass, sodium waterglass (Betol 57 from Woellner GmbH) was used.

(23) The tensile strength increased to 6.1 kPa (with foam). Note that the adhesion strength (adhesion of blankets) was higher than 6.1 kPa as there was cohesive failure in blanket.

11. Example 11

(24) The example was carried out as described in example 6 with the difference that instead of VP 19621, K42 (from Woellner GmbH) waterglass was used.

(25) The tensile strength increased from 3.6 kPa (without foam) to 16.15 kPa (with foam).

12. Example 12

(26) The example was carried out as described in example 6 with the difference that the instead of 0.5 g, 0.6 g surfactant was used.

(27) The tensile strength increased from 3.6 kPa (without foam) to 16.3 kPa (with foam).

13. Example 13

(28) The example was carried out as described in example 6 with the difference that the fibers from the blanket were partially pulled out surface using a brush.

(29) The tensile strength increased from 3.6 kPa (without foam) to 13.35 kPa (with foam).

14. Example 14

(30) The example was carried out as described in example 6 with the difference that that 12 g water was added in the mixture.

(31) The tensile strength increased from 3.6 kPa (without foam) to 9.4 kPa (with foam).