Foam separator for polyurethane foams

Abstract

A process can be used for preparing thermally insulating articles containing a thermally insulating polyurethane foam producible in place, a casing surrounding the thermally insulating polyurethane foam, and a foam separator located within the thermally insulating polyurethane foam. The thermally insulating articles producible according to this process are useful. Corresponding cooling systems like fridges, heat storage systems, insulation panels for construction, insulated pipes, mobile transport systems, water boilers, burners, chimneys, instrument panels, roofs of industry hails, engines, or caravans contain the thermally insulating article.

Claims

1-18. (canceled)

19. A process for preparing a thermally insulating article, the process comprising: injecting a polyurethane foam reaction mixture into at least one first inlet of a casing, and foaming the polyurethane foam reaction mixture; wherein the thermally insulating article comprises: a thermally insulating polyurethane foam producible in place by foaming a foam reaction mixture, and the casing surrounding the thermally insulating polyurethane foam, said casing comprising the at least one first inlet for the injection of the polyurethane foam reaction mixture, at least one air outlet for air displaced during the foaming of the polyurethane foam reaction mixture, and at least one foam separator; wherein during the injection and/or foaming, at least two streams of the polyurethane foam reaction mixture converge within the casing, wherein the at least one foam separator is provided along an area of convergence of the at least two streams, and wherein the area of convergence means an area where the at least two streams of the polyurethane foam reaction mixture would meet and converge in case there would be no foam separator.

20. The process according to claim 19, wherein the at least two streams of the polyurethane foam reaction mixture are generated from a first stream of the polyurethane foam reaction mixture by an obstacle located within the casing, within a flow direction of the first stream of the polyurethane foam reaction mixture, dividing the first stream into the at least two streams.

21. The process according to claim 19, wherein the casing comprises at least one second inlet for the polyurethane foam reaction mixture and wherein at least one of the at least two streams of the polyurethane foam reaction mixture stems from the polyurethane foam reaction mixture injected into the at least one first inlet and at least one of the at least two streams of the polyurethane foam reaction mixture stems from the polyurethane foam reaction mixture injected into the at least one second inlet.

22. The process according to claim 19, wherein the casing includes a continuous opening.

23. The process according to claim 19, wherein the at least one foam separator is laminar.

24. The process according to claim 19. wherein the at least one air outlet is provided in the casing at an upper end of the at least one foam separator.

25. The process according to claim 19, wherein the at least one air outlet is located at a rear end of the at least one foam separator seen in a flow direction of the at least two streams of the polyurethane foam reaction mixture.

26. The process according to claim 25, wherein the at least one air outlet is a slit like opening arranged along the rear end of the at least one foam separator.

27. The process according to claim 19, wherein the at least one air outlet is closed with a material pervious to air.

28. The process according to claim 19, wherein the at least one foam separator is made of at least one material selected from the group consisting of metal; wood; foam; plastic; and reinforced plastic.

29. The process according to claim 19, wherein the at least one foam separator is coated by an adhesion promoting agent.

30. The process according to claim 19, wherein the thermally insulating polyurethane foam is a rigid polyurethane foam.

31. The process according to claim 19, wherein the thermally insulating polyurethane foam is a closed-cell foam.

32. The process according to claim 19, wherein the thermally insulating polyurethane foam has a density of 20 to 300 kg/m.sup.3.

33. The process according to claim 19, wherein the thermally insulating article is an article selected from the group consisting of a housing of a cooling application; a housing of a heal storage system; a pipe; a construction board; a side wall of a caravan, a panel for roofs from industry halls; a housing of a water boiler, a burner, or a chimney; a cover of an instrument panel; and an engine casing.

34. The thermally insulating article produced by the process according to claim 19.

35. A thermally insulating article, comprising: an in-place-foamed thermally insulating polyurethane foam, and a casing surrounding the in-place-foamed thermally insulating polyurethane foam, said casing comprising at least one inlet for injection of a polyurethane foam reaction mixture for in-place-foaming the thermally insulating polyurethane foam, at least one air outlet for air displaced during the in-place-foaming of the thermally insulating polyurethane foam, and at least one foam separator; wherein the at least one foam separator is located within the in-place-foamed thermally insulating polyurethane foam along an area of convergence of at least two streams of the polyurethane foam reaction mixture during the in-place-foaming of the thermally insulating polyurethane foam, and wherein the area of convergence means an area where the at least two streams of the polyurethane foam reaction mixture would meet and converge in case there would be no foam separator.

36. A cooling system, comprising the thermally insulating article according to claim 34, wherein the cooling system is an article selected from the group consisting of a fridge, a heat storage system, an insulation panel for construction, an insulated pipe, a mobile transport system, a water boiler, a burner, a chimney, an instrument panel, a roof of an industry hall, an engine, and a caravan.

37. The process according to claim 28, wherein the metal is selected from the group consisting of aluminum and steel; and wherein the plastic is selected from the group consisting of a polyamide, a polyester, a polystyrene, and a styrene-acrylonitrile copolymer.

38. A cooling system, comprising the thermally insulating article according to claim 35, wherein the cooling system is an article selected from the group consisting of a fridge, a heat storage system, an insulation panel for construction, an insulated pipe, a mobile transport system, a water boiler, a burner, a chimney, an instrument panel, a roof of an industry hall, an engine, and a caravan.

Description

EXAMPLES

[0082] Simulations of the filling process were performed for two different casings by 3D CFD-simulation (Computational-Fluid-Dynamics) over time. OpenFoam (www.openfoam.com) Volume of Fluid (VOF) solver was extended to foaming systems. Separate functions for both density and viscosity over time were required. At the beginning the reacting fluid system was injected with a specified mass flow. During the foaming reaction the air pesent in the casing is displaced and the foaming system extends in the direction of the outlet.

[0083] The effect of the presence of a foam separator in a casing which is filled with a foam reaction mixture is shown by means of simulation data. The volume to be foamed was determined based on the geometry of the cavity to be filled. The targeted density at the end of the simulation was predefined. This predefined value determined the required amount of fluid to be injected and together with a typical time of injection of 3 to 8 sec the mass flow rate at the inlet was calculated.

[0084] The results of the simulation of the filling of a casing are shown in FIGS. 2 and 3 in three-dimensional schemes. In FIGS. 2a) and 3a) casings are shown with one lateral inlet for injection (3) and an obstacle (6) dividing the stream of foam reaction mixture injected by the lateral inlet (3) into two streams. Both casings are displayed with the foam separator (5). The casings of FIGS. 2a) and 3a) are different in respect of the placement of the air outlet(s). In FIG. 2a) a slit like air outlet (4) is provided at the rear end of the foam separator (5) extending along the whole wall vertical to the foam separator in the upper end of the casing. In FIG. 3a) two small air outlets (4, 4′) are provided at the upper end of the casing and the foam separator (5), one at the right end close to the obstacle and one on the left end at the crossing point of separator and upper wall. In FIGS. 2b) and c) the results for filling the casing of FIG. 2a) without and with a foam separator and in FIGS. 3b) and c) the results for filling the casing of FIG. 3a) without and with a foam separator are displayed. The dark gray areas within the foam denote areas with inhomogeneous density distribution as indication of inhomogeneous flow and bad mixing of the two streams generated by the obstacle. In FIG. 2b) the inclined weld line is visible, whereas in FIG. 2c) the foam separator leads to a straight line in the area of convergence and homogeneous filling of the casing. In FIG. 3b) and c) magnifications of the right corners of the casings are displayed demonstrating that the foam separator leads to a better filling of the edges at the rear end of the casing and inhibits the inclined weld line.