Bi-material sandwich panel and manufacturing process.

Abstract

The invention relates to a sandwich panel (100) comprising an insulating core (110) sandwiched between two metal plates which also serve as facings, wherein: - each metal plate comprises an inner face, intended to be in contact with the core (110) of the panel, and an outer face, opposite the inner face, - the insulating core (110) comprises a layer of bio-based insulating material (111) in the form of a plate. It is essentially characterized in that: - the insulating core (110) further comprises a layer of polymer foam (112). Figure for the abstract: Fig. 3

Description

Title of the invention: Bi-material sandwich panel and manufacturing process.

[0001] A sandwich panel is a modular building element composed of an insulating core and rigid facings on each of its two faces.

[0002] Each facing of a sandwich panel is a metal plate, ensuring the rigidity of the panel.

[0003] The commonly used core material, polyurethane foams, is derived from petrochemicals, contradicting an ecological approach.

[0004] It is therefore useful to develop a bio-based material capable of replacing current insulation materials.

[0005] Thus, in recent years we have seen the development of sandwich panels whose core material is a so-called "natural" material, typically rock wool, which is known for its insulating acoustic properties.

[0006] In this case, the rock wool is glued to each metal plate of the facing, in this case a sheet of steel or aluminum.

[0007] However, over time, particularly when a sandwich panel is placed on a ceiling, i.e. in a horizontal plane, it sometimes happens that the rock wool detaches from a plate, which destructures the panel by delamination.

[0008] The present invention aims to improve the state of the art by proposing a particularly ingenious solution.

[0009] To this end, according to a first of its objects, the invention relates to a sandwich panel (100) comprising an insulating core (110) sandwiched between two metal plates also serving as facing, in which:

[0010] - each metal plate includes an inner face, intended to be in contact with the core (110) of the panel, and an outer face, opposite the inner face,

[0011] - the insulating core (110) comprises a layer of bio-based insulating material (111) under plate shape.

[0012] It is essentially characterized in that:

[0013] - the insulating core (110) further comprises a layer of polymer foam (112).

[0014] It can be foreseen that the bio-based insulating material (111) is of natural origin, derived from plant or animal biomass, or mineral wool, and comprises at least one of: hemp wool, cotton wool, wadding or cellulose fibers, wood fibers, cork, flax, rock wool, glass wool, cereal straw.

[0015] It can be anticipated that the polymer foam layer (112) is in direct contact with the bio-based insulating material layer (111).

[0016] It can be predicted that the thermal conductivity of said panel is less than or equal to 0.042 W / mK

[0017] It can be foreseen that at least one of the metal plates comprises a set of through holes (121).

[0018] It can be predicted that:

[0019] - the thickness of the layer of bio-based insulating material (111) is greater than or equal to at 20mm, and

[0020] - the thickness of the polymer foam layer (112) is greater than or equal to 20mm.

[0021] According to another of its objects, the invention relates to a method for manufacturing a sandwich panel (100), comprising steps consisting of:

[0022] - Arrange a first sheet metal plate, called the lower plate (120), from a side pre-cut or from the unwinding of a first reel,

[0023] - Arrange a second sheet metal, called the top plate (130), from a side pre-cut or from the unwinding of a second reel, the upper plate (130) being positioned above the lower plate (120) and of the same width;

[0024] - To provide an insulating core (110) comprising a layer of insulating material bio-based (111) on the lower plate (120).

[0025] It is essentially characterized in that it further comprises steps consisting of:

[0026] - Depositing a set of at least one reagent onto the layer of insulating material bio-based (111), to obtain a layer of polymer foam (112) on said layer of bio-based insulating material (111);

[0027] - Place the upper plate (130) in contact with the polymer foam layer (112);

[0028] - Arrange the assembly including the lower plate (120), the layer of material bio-based insulation (111), the polymer foam layer (112) and the top plate (130) in a former and maintain said assembly at predetermined pressure and temperature for a predetermined time; and

[0029] - Optionally cut the assembly including the lower plate (120), the layer of bio-based insulating material (111), polymer foam layer (112) and top plate (130) according to a predetermined length, corresponding to the length, or height, of the sandwich panel (100).

[0030] It can be foreseen that the step of depositing a set of at least one reagent onto the layer of bio-based insulating material (111) includes spraying a set of at least one reagent to obtain a polymer foam layer (112) on the layer of bio-based insulating material (111), the spraying being carried out by a spray rake (200) comprising a plurality of spray heads arranged over the width of the sandwich panel (100).

[0031] The polymer can be expected to be polyurethane, the step of which consists of depositing a set of at least one reagent on the layer of bio-based insulating material (111) including spraying a mixture of liquid polyol and isocyanate (220).

[0032] A further step can be envisaged consisting of:

[0033] - Place the sandwich panel (100) in a former whose temperature constant and predetermined, for a predetermined duration.

[0034] Thanks to its double-layer insulating core which includes a layer of bio-based insulating material and a polymer layer, the sandwich panel according to the invention is anisotropic.

[0035] Other features and advantages of the present invention will become more apparent from the following description given by way of illustrative and non-limiting example and made with reference to the accompanying figures.

[0036] *Figures*

[0037] [Fig. 1] illustrates a cross-section of an embodiment of a sandwich panel according to the invention;

[0038] [Fig.2] illustrates a cross-section of another embodiment of a sandwich panel according to the invention;

[0039] [Fig.3] is a photograph of an embodiment of a sandwich panel according to the invention;

[0040] [Fig.4] illustrates in top view the spraying of reagent to form a layer of polymer foam on a layer of bio-based insulating material, in a continuous online manufacturing process.

[0041] An embodiment of a sandwich panel 100 according to the invention is illustrated in [Fig.3].

[0042] In this case, the sandwich panel 100 is bi-material, that is to say, it comprises two layers of different insulators, which correspond to the insulating core 110 of the sandwich panel 100.

[0043] The insulating core 110 is sandwiched between two metal plates: a first sheet, called the lower plate 120 and a second sheet, called the upper plate 130.

[0044] By upper and lower, reference is made to a sandwich panel 100 placed in a horizontal position, the lower sheet being the lowest, or closest to the ground, and the upper sheet being the highest, i.e. the furthest from the ground or closest to a ceiling.

[0045] Note that this definition is purely conventional: in use, a sandwich panel 100 can be placed in a horizontal position indiscriminately with the lower plate 120 closest to the ground or closest to the ceiling.

[0046] The lower sheet metal comprises an inner face, intended to be in contact with the core 110 of the panel, and an outer face, intended to be in contact with the open air.

[0047] The first sheet can come from a pre-cut side, or from the unwinding of a first coil in a continuous line.

[0048] The second sheet can also be from a pre-cut side, or from the unwinding of a second coil in a continuous line, the upper plate 130 being of the same width as the lower plate 120.

[0049] In a manner known per se, as illustrated in the figures, the ends of the lower plate 120 and the upper plate 130 are preferably machined so as to present, in cross-section, a corresponding male and female profile. Thus, the sandwich panels can be joined in pairs to form a rigid and stable wall.

[0050] The lower plate 120 and the upper plate 130 also serve as facing. It can be provided that at least one of them includes a set of through holes 121 (see [Fig.3]), which makes it possible to increase the sound insulation performance.

[0051] Each metal plate comprises an inner face and an outer face, opposite to the inner face.

[0052] By convention, the inner face is intended to be in contact with the core 110 of the sandwich panel 100. Generally, the outer face is in the open air, and can be juxtaposed to a pre-existing wall, a wall or other.

[0053] The insulating core 110 comprises two layers of insulating materials.

[0054] By "insulating material" is meant a material which has thermal insulation properties such that the thermal conductivity of said panel is less than or equal to a predetermined threshold value, in this case 0.042 W / mK

[0055] Advantageously, the insulating material also exhibits sound insulation properties, such that its acoustic impedance is greater than or equal to a predetermined threshold value.

[0056] Typically a first layer of insulating material of the insulating core 110 is a bio-based insulating material, which in this case is in the form of a plate.

[0057] As illustrated in [Fig.1], it can be foreseen that a sandwich panel 100 comprises a set of plates of bio-based insulating material, the plates being adjacent in pairs.

[0058] The bio-based insulating material is of natural origin, derived from plant or animal biomass. It can also be a mineral wool such as rock wool, glass wool, etc.

[0059] For example, one can foresee, taken alone or in combination: hemp wool, cotton wool, wadding or cellulose fibers, wood fibers, cork, flax, rock wool, glass wool, cereal straw, in particular rice straw.

[0060] In the case of wood fibers, delignification of the wood is preferred, as it increases the porosity of the wood and consequently reduces its density and thermal conductivity. The cell wall of wood comprises cellulose, hemicellulose, and lignin. Among these components, lignin is the natural glue between wood cells and between constituents of the cell wall. The cellulose in the so-called "S2" layer of the secondary cell wall, the thickest layer, is almost vertically aligned. By delignifying the wood, the spaces previously occupied by lignin and hemicellulose allow the creation of nanopores, in addition to the lumens already present in the fibers. The preservation of the natural hierarchical structure of the cellulose nanofibers thus contributes to their high thermal and mechanical properties.

[0061] It can be foreseen that the bio-based insulating material is glued to the inner face of the metal plate.

[0062] Bio-based materials, such as mineral wool, have a mechanical defect: they are not self-supporting. This is why sandwich panels include two metal plates that stiffen them and also serve as facing.

[0063] According to the invention, a second layer of insulating material of the insulating core 110 is a layer of polymer foam 112, which is advantageously self-supporting.

[0064] For example, the polymer is polyester or polyurethane.

[0065] Advantageously, the polymer foam layer 112 is in direct contact with the bio-based insulating material layer. That is to say, it is not necessary to deposit a layer of adhesive between the polymer foam layer 112 and the bio-based insulating material layer.

[0066] In the figures, the thickness of the bio-based insulating material layer is assumed to be equal to the thickness of the polymer foam layer 112. Of course, depending on the desired insulation properties, the thickness of the bio-based insulating material layer may differ from the thickness of the polymer foam layer 112.

[0067] Preferably, the thickness of the layer of bio-based insulating material is provided to be between 20 mm and 220 mm.

[0068] Similarly, it is preferably provided that the thickness of the polymer foam layer 112 is between 20 mm and 220 mm. Manufacturing

[0069] For the manufacture of a sandwich panel 100, a first sheet, or lower plate 120, is to be placed on a support.

[0070] The lower plate 120 can be either from a pre-cut side, or from the unwinding of a first reel in a continuous line.

[0071] A second sheet, or upper plate 130, is planned to be placed above the lower plate 120 and to have the same width as the latter. The upper plate 130 can also be either from a pre-cut blank or from the unwinding of a second continuous roll, unwound simultaneously with the first roll of sheet, in strips between which the insulating core 110 of the sandwich panel 100 is formed.

[0072] A layer of bio-based insulating material can then be placed on the lower plate 120. In this case, a layer of bio-based insulating material is placed on the lower plate 120, which has been previously coated with a layer of adhesive. The layer of bio-based insulating material can be in the form of a single plate with the dimensions of the lower plate 120, or a set of plates placed two by two, as illustrated in [Fig. 1]. For example, the material is a rock wool panel in slab form, with predetermined dimensions, for example 2400 mm x 200 mm, and a predetermined thickness and density.

[0073] We can then deposit a set of at least one reagent on the layer of bio-based insulating material, the reagent allowing to obtain a layer of polymer foam 112 on said layer of bio-based insulating material.

[0074] In one embodiment, the polymer is polyurethane. In this case, a mixture of polyol liquid and isocyanate 220 is planned to be sprayed by extrusion onto the layer of bio-based insulating material, in this case by a spray rake 200 comprising a plurality of spray heads 210 arranged over the width of the sandwich panel 100, as illustrated in [Fig.4].

[0075] In this case, the manufacturing process is said to be continuous line and the arrow on [Fig.4] indicates the direction of travel of a sheet metal coil, in this case the lower plate 120.

[0076] The spraying of the polyol liquid and isocyanate 220 mixture is carried out by continuous injection, also called spreading.

[0077] In this case, the injection of the liquid mixture of polyol and isocyanate is carried out with an injection rake comprising a plurality of 210 injection heads, or nozzles, so that the spreading covers the width of the panel.

[0078] In this case, the liquid mixture of polyol and isocyanate is injected through an injection nozzle, which in this case is immobile and arranged between the lower and upper sheets.

[0079] Preferably, the spray heads 210 are configured so that the width of the bio-based insulating material layer, i.e., the width of the sandwich panel 100, is covered by the spray. The number of spray heads, their position on the rake, and the distance between the rake and the bio-based insulating material layer are therefore adjusted according to the width of the sandwich panel 100 and the spray angle of the spray heads.

[0080] When the polymer is polyurethane, the mixture of polyol liquid and isocyanate 220 foams naturally. Advantageously, polyurethane has naturally sticky properties, so it is not necessary to deposit a layer of adhesive between the layer of bio-based insulating material and the polymer foam layer 112.

[0081] The polyurethane foam is contained between the bio-based material layer and the top sheet metal. On the lateral sides of the 100 mm sandwich panel being manufactured, the polyurethane foam is contained by longitudinal molds arranged in the direction of the sheet metal rolls. The molds are protected by a protective film and are in contact with the edges of the top and bottom sheets.

[0082] Once the polymer foam layer 112 is placed on the bio-based insulating material layer, the top plate 130 can be placed in contact with the polymer foam layer 112.

[0083] In a manner known per se, and as illustrated in [Fig. 2], the lower plate 120 and the upper plate 130 can be bent at one end to form a female profile, and folded back on themselves at the opposite end to form a male profile, complementary to the female profile, so that the panels can be fitted together in pairs. In this case, the sheets are profiled by a profiling machine.

[0084] The assembly comprising the lower plate 120, the layer of bio-based insulating material, the polymer foam layer 112, and the upper plate 130 can then be placed in a former, which maintains said assembly at a predetermined pressure and temperature for a predetermined time, in particular so that the polymer foam 112 solidifies and thus exhibits mechanical rigidity properties in addition to its insulating properties. In this case, in a continuous line configuration, the former is at 40°C + / - 10%, which allows the polyurethane foam to adhere to the sheet metal, in this case the upper plate.

[0085] Advantageously, the polymer foam 112 is in contact with the upper plate 130, either directly, for example when the polymer is polyurethane, or possibly via a layer of glue.

[0086] When manufacturing takes place in a continuous line, the assembly comprising the lower plate 120, the layer of bio-based insulating material, the polymer foam layer 112 and the upper plate 130 is then planned to be cut to a predetermined length, corresponding to the length, or height, of the sandwich panel 100.

[0087] In continuous line, the polymer foam layer 112 and the bio-based insulating material layer are not glued to each other by a layer of glue but are advantageously produced simultaneously.

[0088] Preferably, the inner face of the upper sheet is pre-treated, for example with a degreaser, to facilitate the adhesion of the polymer, in particular polyurethane.

[0089] Polyurethane is inherently sticky. Thanks to this characteristic, spraying polyurethane onto the layer of bio-based insulating material allows it to penetrate the layer, thus adhering to it, and then foaming.

[0090] Preferably, the speed of the bio-based insulating material layer, the speed of the sheet metal rolls and the polyurethane spray rate are to be adjusted in particular according to the thickness of the bio-based insulating material layer.

[0091] In practice, the polyurethane is sprayed in liquid and foam form abruptly, in the form of an expanding wave. Preferably, the spray rate is proportional to the thickness of the sandwich panel.

[0092] In a continuous line, the two coils of sheet metal are arranged at a starting point at two different heights, for example at 1.50 m above the ground for the lower coil of sheet metal, and at 3.50 m above the ground for the upper coil of sheet metal. The upper and lower sheets of sheet metal therefore have an initial gap, in this case of 2 m.

[0093] A guiding system guides the upper sheet as it moves along, reducing the gap between the two sheets and bringing the initial gap back to a final gap, at a forming point where the gap between the two sheets is, in this case, equal to the desired thickness of the panel. This gap is then maintained, including within the former.

[0094] The injection rake is positioned on the production line between the starting point and the forming point. In this case, the injection rake is positioned at the forming point.

[0095] Upon exiting the former, the panel is cut to the desired dimensions. Preferably, the cut panel is held in a stable position for a predetermined period, in this case 24 hours, thus maintaining the internal temperature of the foam has returned to room temperature, so as to ensure that the chemical foaming reactions are complete.

[0096] By comparing two sandwich panels of the same dimensions (length or indistinctly height, width) and of the same thickness, one of which comprises only rock wool and the other is according to the present invention, the sandwich panel 100 according to the present invention is lighter since the density of polyurethane is less than the density of rock wool.

[0097] In addition, it is recognized that polyurethane foam is about 2 times more efficient than rock wool in terms of thermal insulation.

[0098] Consequently, for two sandwich panels of the same dimensions, one composed solely of rock wool and the other according to the present invention, the sandwich panel 100 according to the present invention can be approximately half as thick to achieve the same thermal insulation performance. Alternatively, for the same thickness, the sandwich panel 100 according to the present invention is approximately twice as effective.

[0099] The 100 sandwich panel according to the present invention also has the advantage of the sound insulation properties of rock wool.

[0100] Furthermore, the 100 sandwich panel according to the present invention has superior mechanical resistance properties to those of a 100 sandwich panel of the same dimensions which comprises only rock wool, since the mechanical resistance of polyurethane foam is superior to that of rock wool.

[0101] It should also be noted that for a 100 mm sandwich panel composed solely of rock wool, there is a gravitational phenomenon whereby, when the 100 mm sandwich panel is positioned vertically, the rock wool tends to settle, which reduces the performance of the panel in its upper part and thus creates inhomogeneity. In contrast, according to the invention, polyurethane foam retains its rigidity and does not experience this settling phenomenon.

[0102] With regard to sound insulation, it should be noted that the properties of a 100 sandwich panel according to the invention differ from those of a 100 sandwich panel which comprises only rock wool since the sound absorption or transmission properties of rock wool are different from those of polyurethane foam.

[0103] Preferably, a 100 sandwich panel according to the invention is provided to comprise a layer of rock wool of at least 20mm thickness and a layer of polyurethane foam of at least 20mm thickness.

[0104] It can be foreseen that a 100 sandwich panel according to the invention comprises in thickness a distribution of 50% rock wool and 50% polyurethane foam.

[0105] In this case, it can be foreseen that a 100 sandwich panel according to the invention has a total thickness of 200mm.

[0106] A 100 sandwich panel according to the invention can advantageously be arranged horizontally, for example as a ceiling, or vertically, as a wall.

[0107] A 100 mm sandwich panel according to the invention can advantageously be used indoors or outdoors as cladding. Preferably outdoors, a joint comprising a vapor barrier film is provided between two adjacent sandwich panels.

[0108] Particularly outdoors, depending on the difference in outside temperature between the two faces of the sandwich panel 100, a bending phenomenon, i.e., thermal deformation, can occur, causing the sandwich panel 100 to curve. Thanks to the elastic properties of polyurethane foam, a sandwich panel 100 according to the invention exhibits better mechanical resistance to this thermal bending phenomenon. Nomenclature

[0109] 100 Sandwich panel

[0110] 110 insulating core

[0111] 111 bio-based insulating material

[0112] 112 polymer foam

[0113] 120 lower plate

[0114] 121 through holes

[0115] 130 top plate

[0116] 200 spray rake

[0117] 210 spray head

[0118] 220 mixture of polyol liquid and isocyanate

Claims

Demands

1. Sandwich panel (100) comprising an insulating core (110) sandwiched between two metal plates also serving as facing, in which: - each metal plate comprises an inner face, intended to be in contact with the core (110) of the panel, and an outer face, opposite to the inner face, - the insulating core (110) comprises a layer of bio-based insulating material (111) in the form of a plate, - the insulating core (110) further comprises a layer of polymer foam (112) characterized in that: at least one of the metal plates comprises a set of through holes (121).

2. Sandwich panel (100) according to claim 1, wherein the bio-based insulating material (111) is of natural origin, derived from plant or animal biomass, or mineral wool, and comprises at least one of: hemp wool, cotton wool, wadding or cellulose fibers, wood fibers, cork, flax, rock wool, glass wool, cereal straw.

3. Sandwich panel (100) according to any one of the preceding claims, wherein the polymer foam layer (112) is in direct contact with the bio-based insulating material layer (111).

4. Sandwich panel (100) according to any one of the preceding claims, wherein the thermal conductivity of said panel is less than or equal to 0.042 W / mK

5. Sandwich panel (100) according to any one of the preceding claims, wherein the two metal plates comprise a lower plate (120) and an upper plate (130); and wherein the ends of the lower plate (120) and the upper plate (130) have, in cross-section, a male profile and a corresponding female profile, so that the sandwich panels can be joined two by two to form a rigid and stable wall.

6. Sandwich panel (100) according to any one of the preceding claims, wherein: - the thickness of the bio-based insulating material layer (111) is greater than or equal to 20 mm, and - the thickness of the polymer foam layer (112) is greater than or equal to 20mm.

7. A method for manufacturing a sandwich panel (100), comprising the steps of: - Place a first sheet, called the bottom plate (120), from a pre-cut side or from the unwinding of a first reel, - Place a second sheet, called the upper plate (130), from a pre-cut side or from the unwinding of a second reel, the upper plate (130) being placed above the lower plate (120) and of the same width; - Place an insulating core (110) comprising a layer of bio-based insulating material (111) on the lower plate (120); Characterized in that it further comprises steps consisting of: - Deposit a set of at least one reagent onto the bio-based insulating material layer (111), to obtain a polymer foam layer (112) on said bio-based insulating material layer (111); - Place the top plate (130) in contact with the polymer foam layer (112); - Place the assembly comprising the bottom plate (120), the bio-based insulating material layer (111), the polymer foam layer (112) and the top plate (130) in a former and maintain said assembly at predetermined pressure and temperature for a predetermined time; and - Optionally cut the assembly comprising the bottom plate (120), the bio-based insulating material layer (111), the polymer foam layer (112) and the top plate (130) to a predetermined length, corresponding to the length, or height, of the sandwich panel (100);- the polymer foam layer (112) and the bio-based insulating material layer (111) being produced simultaneously.;

8. A method according to claim 7, wherein the step of depositing a set of at least one reagent onto the bio-based insulating material layer (111) comprises spraying a set of at least one reagent to obtain a polymer foam layer (112) on the bio-based insulating material layer (111), the spraying being carried out by a spray rake (200) comprising a plurality of spray heads arranged over the width of the sandwich panel (100).

9. A method according to claim 8, wherein the polymer is polyurethane, the step of consisting of depositing a set of at least one reagent onto the layer of bio-based insulating material (111) comprising spraying a mixture of liquid polyol and isocyanate (220).

10. A method according to any one of claims 7 to 9, further comprising a step consisting of: Place the sandwich panel (100) in a former whose temperature is constant and predetermined, for a predetermined duration.

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