EP1755853A1

EP1755853A1 - Process for manufacturing insulating panels with polimeric foam and mineral wool

Info

Publication number: EP1755853A1
Application number: EP04730917A
Authority: EP
Inventors: Maurizio Morandi
Original assignee: Metecno SpA
Current assignee: Metecno SpA
Priority date: 2004-05-03
Filing date: 2004-05-03
Publication date: 2007-02-28
Also published as: CN1953859A; WO2005105406A1; JP2007536138A; AU2004319030A1

Abstract

The invention relates to a process for manufacturing insulating panels using a layer of polymer foam (10) and a layer of mineral wool (12). In order to obtain uniform expansion of the resin forming the insulating foam, an interface (15) is applied onto the fibrous layer of mineral wool so as to reduce the frictional resistance to the resin as it expands. Advantageously this interface may be obtained by spraying a film of the same resin as the foam.

Description

Process for manufacturing insulating panels with polimeric foam and mineral wool The invention relates to the process for manufacturing insulating panels having a composite or so-called "sandwich" structure, wherein an insulating core consisting of at least one layer of mineral wool and one layer of polymer foam is arranged between two external surfaces made of sheet metal, plastic or other material. These panels are used in particular for fire-prevention applications since mineral wool has good fire-resistance properties, unlike polymer foam which usually is expanded polyurethane or another expanded resin and which instead has a greater heat-insulating capacity, further to a greater structural rigidity compared to mineral wool. A difficulty which is encountered in the manufacture of this kind of panel consists in the fact that the fibres of mineral wool prevent expansion of the resin in a direction tangential to the interface with the wool, with the result that the foam does not reach properly all the zones inside the panel or in any case its expansion is slowed down. In order to overcome this situation it is known to spread or in any case to distribute the liquid resin in the most uniform manner possible, over the whole surface of the panels; however, this is not always possible owing to the form and the dimensions of the panels, in particular in the case of discontinuous production thereof. Indeed, during such production, the resin is usually poured in one or in any case in few spots, so that it expands mainly in a direction parallel to the surface of the wool for reaching all the spaces inside the panel; however, the fibrous surface of the wool is a source of friction which prevents expansion of the foam along the interface. The present invention aims at solving this problem: namely it has the object of providing a process for manufachiring insulating panels with a core consisting of mineral wool and polymer foam, which is able to overcome the negative effects of the friction generated by the fibrous surface of the wool. The idea for solving this jproblem consists in applying onto the surface of the mineral wool an interface made of a material that adheres properly both to the foam and to the wool, so as to avoid separation phenomena or defects in the panel structure. This material, in accordance with a preferred embodiment of the invention, consists of the same polymer resin as the foam and is applied by means of spraying onto the surface of the mineral wool. In this way it is possible to obtain on the one hand the compatibility of the sprayed interface with the foam, thereby ensuring their perfect adhesion with each other, and on the other hand the attachment of said interface to the wool as normally occurs in the case of foam. The characterising features of the process for manufacturing panels according to the invention are stated in the claims appended to this description; these features will become clear from the embodiment of the invention provided hereinbelow with reference to the accompanying drawings, wherein: - Fig. 1 shows a panel in accordance with the invention; - Fig. 2 shows a detail of the cross-section of the panel according to Fig. 1; - Fig. 3 shows a cross-sectional view of a variant of the above panel; - Figs. 4 and 5 shows the steps for carrying out the process of the invention, according to the respective variants thereof. In the first figure an insulating panel in accordance with the invention is denoted overall by 1 ; it comprises an upper face 2 and a bottom face 3 made of sheet metal profiled with a series of ribs 5, 6 and 7, having a form known in the art. An insulating core formed by a layer 10 of polymer foam, preferably expanded polyurethane, and a layer 12 of mineral wool, is provided between the two faces of the panel. An interface 15 consisting of expanded resin of the same type as that of the polymer foam, is provided between the layers 10 and 12; the thickness of the interface 15 is chosen so as to ensure the necessary flexibility for adaptation to the subsequent expansion of the foam 10. Consequently, there will be some cases where the interface is a thin film and other cases where it is a few millimetres thick; this will depend on the type of resin used, on its density and on the form and size of the insulating core, etc. The operating steps for manufacturing the panels according to two possible variants of the process of the invention are illustrated schematically in Figures 4 and 5. As can be seen in step (a), after the mineral wool 12 has been glued onto the second face 3 of the panels, the polymer resin is sprayed using a head 17 over the whole upper surface of the wool 12, forming the interfacing film 15 thereon. The liquid (or in any case fluid) resin is poured onto the face 2 of the panel, i.e. the face which has the higher ribs 5, using a second head 18 (c.f. step (b)); the liquid resin is applied at only one point on the face 2 of the panel. After this operation, using a mould of the known type, the other face 3 of the panel is placed with the interface 15 directed downwards at a distance equal to the thickness of the panel; the semi-finished product thus prepared is placed inside a press (not shown yet known per se), where expansion of the resin takes place. Owing to the interface formed by the resin sprayed onto the wool 12, the foam expands regularly filling uniformly the spaces inside the panel; this is due to the aforementioned interface which forms a regular surface over which the foam can creep without encountering friction which instead characterizes the fibrous surface of mineral wool. Fig. 5 shows a variant of the process described above, where in step (b) the liquid resin is poured onto the interface 15 of sprayed resin on the wool 12, instead of onto the other face 2 of the panel; the latter is then placed inside a mould at a distance equal to the thickness of the panel (c.f. step (c)) and after this the whole assembly is introduced in the press for expansion of the resin and consequent formation of the foam 10. As can be seen, the process according to the invention has the advantage that it is flexible and may be implemented in the manner most appropriate for the circumstances; owing to its simplicity said process is therefore suitable for use both in discontinuous production of the panels and in continuous production, namely where the two faces 2 and 3 are obtained by profiling strips of sheet metal unwound from respective coils. Obviously the process according to the invention may also be used for manufacturing panels with a form different from that shown in Fig. 1, for example curved panels such as those produced by the same Applicant, or flat panels such as that in Fig. 3 where for the sake of simplicity equivalent parts have been indicated by adding 20 to the reference numbers in Fig. 1; therefore the panel 21 (i.e. 1+20) comprises an upper face 22 (2+20) and a bottom face 23. In this case the insulating core comprises two layers of mineral wool 32 separated from the polymer foam 30 by respective films 35 obtained as already explained above. Obviously the same comments made above regarding uniform expansion of the foam in the panel, assisted by the films 35, are applicable to this variant too. Also with regard to the materials it is possible to envisage various modifications with respect to what has been described hitherto; for example, it is obvious that the faces of the panels might also not be made of metal. Therefore, as mentioned in the beginning it would be possible to use plastic materials (polycarbonate, polyethylene, etc.) or wood, glass, etc. Moreover, instead of the rock wool, it is possible to use other fibrous materials such as textile materials both with synthetic and natural fibres. Finally it must be added that in principle the wool/foam separation interface could be obtained in a manner other than by using sprayed resin; generally speaking, in fact, any material which is both flexible, not smooth and preferably not porous could be used. On the basis of these requirements persons skilled in the art may find various alternatives. Lastly, repeating what has been already stated above, it should be pointed out that the process according to the invention, although it is particularly suitable for the discontinuous production of panels wherein the faces 2 and 3 are cut separately and the wool and resin then applied as explained, it is also applicable to continuous manufacturing process using production lines where the resin and the mineral wool are applied onto profiled metal strips. These variants nevertheless fall within the scope of the claims which follow.

Claims

CLAIMS 1. Process for manufacturing insulating panels, wherein at least one fibrous layer (12; 32) and one layer (10; 30) of expanded polymer resin are arranged between outer faces (2, 3; 22, 23) facing each other, comprising the following steps: - fixing onto one face (3, 23) of the panel (1, 21) the fibrous layer (12, 32) using glue or other fixing means; - applying onto the free surface of the fibrous layer (12; 32) a flexible interface (15; 35) with a low frictional resistance to the creep of the resin during expansion; - opposing the other face (3; 23) of the panel so that it lays at a predefined distance, after application of the fluid polymer resin; - causing expansion of the fluid polymer resin while keeping the panel inside a press. 2. Process according to Claim 1, wherein the interface (15; 35) is obtained by spraying a polymer resin onto the fibrous layer (12; 32). 3. Process according to Claim 2, wherein the sprayed resin is of the same type as that of the insulating layer (10, 30). 4. Process according to Claims 1 to 3, wherein the fibrous layer (12; 32) consists of mineral wool. 5. Process according to the preceding claims, wherein the outer faces (2, 3; 22, 23) are made of sheet metal. 6. Process according to Claim 5, carried out continuously and wherein the outer faces (2, 3; 22, 23) are formed using respective metal strips. 7. Process according to the preceding claims, wherein the fluid polymer resin is poured onto the interface (15) or onto one face (2, 22) of the panel opposite thereto, being concentrated in at least one point. 8. Panel manufactured with the process according to the preceding claims, characterized in that it comprises an interface (15) between a fibrous layer (12; 32) and a layer of expanded polymer resin (10; 30) arranged between the outer faces (2, 3; 22, 23). 9. Panel according to Claim 8, wherein said interface is formed by a layer of resin sprayed onto the fibrous layer (12; 32). 10. Panel according to Claim 9, wherein the sprayed resin is of the same type of the expanded resin (10; 30). 11. Panel according to Claims 8 to 10, wherein the fibrous layer (12; 32) consists of mineral wool and the outer faces (2, 3; 22, 23) are made of sheet metal.