METHOD FOR PRODUCING A THERMALLY INSULATING LAYER

Abstract

Process for the simple and practical application of a relatively thick heat-insulating layer to a surface to be insulated by: (a) applying a porous substrate consisting of a spacer fabric to the surface of an article, which surface is to be insulated; (b) filling the porous substrate with a heat-insulating formulation; (c) curing the formulation filled into the porous substrate.

Claims

1-12. (canceled)

13. A process for applying a heat-insulating layer to a surface of an article, which surface is to be insulated, comprising the following steps: a) applying a porous substrate consisting of a spacer fabric to the surface to be insulated; b) filling the porous substrate applied in step a) with a heat-insulating formulation; c) curing the formulation filled in step b).

14. The process of claim 13, wherein the article having the surface to be insulated is selected from the group consisting of wall, ceiling, floor, plate, pipeline and pipe.

15. The process of claim 13, wherein the porous substrate is flexible.

16. The process of claim 15, wherein the porous substrate is selected from the group consisting of synthetic polymers, cellulose-based fibres, cotton, wool, silk, mineral wool, glass wool, metals, carbon fibres and the combinations thereof.

17. The process of claim 13, wherein the spacer fabric has a mesh size of from 2 to 100 mm.

18. The process of claim 13, wherein the porous substrate in step a) is attached mechanically and/or by means of an aid to the surface to be insulated.

19. The process of claim 13, wherein the heat-insulating formulation comprises a binder containing polymerizable substances and/or water.

20. The process of claim 13, wherein the heat-insulating formulation contains silica.

21. The process of claim 13, wherein the heat-insulating formulation contains at least one IR opacifier.

22. The process of claim 13, wherein the heat-insulating formulation contains from 5 to 90% by weight of a binder, from 20 to 95% by weight of a silica, and from 5 to 50% by weight of an IR opacifier.

23. The process of claim 13, wherein the curing taking place in step c) is achieved by at least partial polymerization and/or vaporization of the water.

24. The process of claim 13, wherein the heat-insulating layer after curing has a thickness of more than 1 mm.

25. The process of claim 14, wherein the porous substrate is flexible.

26. The process of claim 25, wherein the porous substrate is selected from the group consisting of synthetic polymers, cellulose-based fibres, cotton, wool, silk, mineral wool, glass wool, metals, carbon fibres and the combinations thereof.

27. The process of claim 26, wherein the spacer fabric has a mesh size of from 2 to 100 mm.

28. The process of claim 27, wherein the porous substrate in step a) is attached mechanically and/or by means of an aid to the surface to be insulated.

29. The process of claim 26, wherein the heat-insulating formulation comprises a binder containing polymerizable substances and/or water.

30. The process of claim 26, wherein the heat-insulating formulation contains silica.

31. The process of claim 26, wherein the heat-insulating formulation contains at least one IR opacifier.

32. The process of claim 26, wherein the heat-insulating formulation contains from 5 to 90% by weight of a binder, from 20 to 95% by weight of a silica, and from 5 to 50% by weight of an IR opacifier.

Description

EXAMPLE 1

[0050] Preparing Heat-Insulating Formulation 1:

[0051] Acronal Eco 6716 (500 g, manufacturer: BASF) and deionized water (50 g) were mixed in a beaker with a 50 mm propeller stirrer at a stirring speed of 750 rpm for 5 minutes. Enova Aerogel IC 3110 (100 g, manufacturer: Cabot) was added to the water/Acronal mixture at an addition rate of 10 g of aerogel per minute. The resultant mixture was stirred at a stirring speed of 750 rpm for a further 10 minutes. The heat-insulating formulation thus obtained had a density of 464 g/l and a solid fraction of 54%.

[0052] Fabric Filling:

[0053] In this example, the spacer fabric from Muller Textiles called T5993-1000-1450-0001 and made of 100% polyester was used. This structure has one ply, a thickness of 10 mm, a basis weight of about 520 g/m.sup.2 and has a mesh size of about 10 mm. The surfaces are kept apart by pile threads which, as a result, give the fabric a certain compressive strength with simultaneous high flexibility and resilience. The piece of fabric with a size of 200 mm200 mm was cut out and placed into a mould with dimensions of 200 mm200 mm10 mm and with a one-ply transparent PE film inlay for visual assessment and simple demoulding. The previously prepared heat-insulating Formulation 1 was rubbed into the fabric by means of a board inclined at 45 with respect to the fabric surface. Said board was brushed over the fabric 2 times in each direction (left-right and top-bottom) at a speed of 200 mm per 10 seconds. While doing so, continuous care was taken that sufficient heat-insulating formulation was available for the filling of the fabric, which formulation was immediately replenished if necessary. After the filling was completed, the excess formulation was removed from the fabric by gently clearing it away using a spatula. During the filling process, the spacer fabric could be filled with the formulation without any difficulties and to a complete extent (degree of filling of virtually 100%) without deformation. The sample thus obtained was removed with PE film and then dried/cured for 7 days at 25 C. and 50% air humidity. The cured product exhibited no cavities or cracks, and the original geometry and volume of the fabric were maintained. The thermal conductivity of the cured product measured using a plate apparatus (EP500, manufacturer: lambda Messtechnik Dresden) at 10 C. mean temperature and 15 K temperature difference and a contact pressure of 2500 Pa was 41.4 mW/(m*K). The most important parameters in carrying out Example 1 are summarized in Table 1 below.

COMPARATIVE EXAMPLE 1

[0054] In this example, Thinsulate G80 (manufacturer: 3M) with mesh size estimated 0.1 mm was used as porous substrate. The filling of said substrate (200 mm200 mm11 mm cut-out) with the heat-insulating Formulation 1 was carried out identically to the procedure described in Example 1. In this case, the fabric could nowhere near be completely filled (degree of filling of 15.6%, based on the original thickness) and it deformed and compressed heavily upon filling. After the curing of the partly filled material for 7 days at 25 C. and 50% air humidity, visual assessment was carried out. In said assessment, it was found that the depth of penetration of the heat-insulating formulation into the fabric was not more than 2 mm, whereas the bottom side of the fabric remained unfilled. This material is unusable for an efficient heat insulation. The most important parameters in carrying out Comparative Example 1 are summarized in Table 1 below.

COMPARATIVE EXAMPLE 2

[0055] In this example, BawiTec-Badewien fibreglass fabric (fly screen, black, PVC-coated, rolled product, width: 120 cm, length: 30 m) with mesh size 1.4 mm1.4 mm was used as porous substrate. Multiple pieces of fabric of size 200 mm200 mm were cut out and combined to achieve a total stack thickness of about 10 mm. Said stack composed of multiple fabric layers was placed into a mould with dimensions of 200 mm200 mm10 mm. The filling of this substrate with the heat-insulating Formulation 1 was carried out identically to the procedure described in Example 1. In this case, the fabric could nowhere near be completely filled (degree of filling 22%), but it did not deform or compress upon filling. After the curing of the partly filled material for 7 days at 25 C. and 50% air humidity, visual assessment was carried out. In said assessment, it was found that the depth of penetration of the heat-insulating formulation into the fabric was not more than 8 of altogether 38 plies used, whereas the remaining plies situated toward the bottom side (direction of PE film) of the stack remained unfilled. This material is unusable for an efficient heat insulation. The most important parameters in carrying out Comparative Example 2 are summarized in Table 1 below.

TABLE-US-00001 TABLE 1 Example 1 Comparative Comparative Spacer fabric, Mller Example 1 Example 2 textiles Thinsulate, 3M Fibreglass fabric, Porous substrate T5993-1000 G80 BawiTec Mesh size, mm 10 0.1 1.4 Number of plies 1 1 38 Basis weight, g/m.sup.2 520 80 109 Thickness of 10 11 0.263 individual ply, mm Thickness of stack, 10 11 10 mm Density, kg/m.sup.3 52 7.3 415 Compression stress 8.5 <0.1 >100 (DIN EN ISO 3386-1), kPa Porosity, % 96.2 99.5 79.3 Empty volume for 20 385 398 317 cm 20 cm 1 cm mould, cm.sup.3 Weight of empty 21 3.2 156 fabric, g Volume of filled fabric, 388 62 71 cm.sup.3 Weight of maximally 202 33 190 filled fabric, g Degree of filling with 100 15.6 22 regard to original porosity, % Thermal conductivity, 41.4 Not measured Not measured mW/(m*K) (incomplete filling) (incomplete filling)

[0056] Use of the spacer fabric as a porous substrate (Example 1) showed major advantages compared to the other types of fabric (Comparative Examples 1 and 2), since the spacer fabric is completely fillable in a very simple manner. Such complete filling ensures a low thermal conductivity, which is required for use in heat insulations. In addition, the use of the spacer fabric does not result in any cavities or cracks, which would increase the risk of corrosion at the insulating materials. Both the relatively wide mesh size of the spacer fabric used (10 mm) and the great mechanical strength of this material exhibit an additional advantageous effect in comparison with the other types of fabric tested.

EXAMPLE 2

[0057] In this example, the spacer fabric from Mller Textiles, 51674 Wiehl, Germany, called T5960-2000-2000-0001 and made of 100% polyester, was used. This structure has a thickness of 20 mm, a basis weight of about 1080 g/m.sup.2 and has cover layers with openings (mesh size) in the range of 5 mm diameter. The surfaces are kept apart by pile threads which, as a result, give the fabric a certain compressive strength with simultaneous high flexibility and resilience. Correctly dimensioned and as a single layer, said spacer fabric was placed around a metal pipe having an inner diameter of 120 mm, a wall thickness of 1 mm and a length of 250 mm and fixed at the butt seam/edge using a sewing thread, and so the spacer fabric fits tightly around the pipe.

[0058] Next, heat-insulating Formulation 2 was manually mixed using a spatula until there was a homogeneous mixture consisting of:

[0059] 1 part expanded glass granulate as bulk material having a particle density of 350 g/l and a thermal conductivity of 70-80 mW/(m*K) from Liaver, for details see: R. Schreiner, E.-G. Hencke, Characterization Work and Comparative Testing of Expanded Glass Granulate as a Round Robin Material for Thermal Conductivity at Higher Temperatures, International Journal of Thermal Sciences, DOI 10.5703/1288284315540. 5 parts RTV silicone (brand b1better savings, transparent silicone, contains biocidal/fungicidal coat preservative (2-octyl-2H-isothiazol-3-one)).

[0060] Said heat-insulating Formulation 2 was then brushed and pressed into the spacer fabric by means of a spatula. Oscillating movements were found to be the best. Thereafter, this pipe specimen was cured at room temperature for 5 days. Then, the pipe was sealed watertight at one opening using a faceplate and filled with water while standing perpendicularly. The water temperature in the pipe was adjusted to 80 C. In the steady state, i.e. after the heating and adjustment of the target water temperature, the temperature of the insulated outer surface of the pipe was determined as 40 C. on the middle of the pipe length using a pyrometer. This experiment took place in a laboratory without forced convection and at air temperatures of 22 C.

[0061] Example 2 shows that the process according to the invention makes it possible to apply a heat-insulating layer of 20 mm thickness to a pipe in a very simple and practical manner.