PANEL WITH FIRE BARRIER

Abstract

A panel with fire barrier comprises: a metal facing; an insulating foam layer; and at least one fire barrier layer between the metal facing and the foam layer, the fire barrier layer(s) comprising at least one of porous silica; hollow glass microspheres; glass fibres; an inorganic ceramifying composition; a dispersion in a polyurethane polymer matrix or polyurethane/polyisocyanurate polymer matrix or polyurethane/polyurea polymer matrix of expandable graphite.

A panel arrangement with fire barrier material in the joint regions between panels, methods of forming the panel and panel arrangement, fire barrier compositions, and reactants for forming the fire barrier compositions are also described.

Claims

1-13. (canceled)

14. A panel comprising: a metal facing; an insulating foam layer; and at least one fire barrier layer between the metal facing and the insulating foam layer, the fire barrier layer(s) comprising a dispersion of expandable graphite in a polyurethane/polyisocyanurate polymer matrix having isocyanate index 1.8 or more.

15. A panel as claimed in claim 14, wherein the fire barrier layer is continuous and is continuously bonded to the metal facing and to the insulating foam layer.

16. A panel as claimed in claim 14, wherein the fire barrier layer is 2 to 20 mm in thickness.

17. A method of forming a panel as claimed in claim 14, comprising the steps of: providing the metal facing with the at least one fire barrier layer; applying the insulating foam layer in the form of a liquid reaction mixture to the fire barrier layer(s); and applying a second metal facing to the insulating foam layer.

18. A method as claimed in claim 17, wherein the at least one fire barrier layer (a) is applied in the form of another liquid reaction mixture, or (b) is applied in solid form.

19. A method as claimed in claim 18, wherein the other liquid reaction mixture is used to form the fire barrier layer and comprises a dispersion in an isocyanate-based reaction mixture of expandable graphite.

Description

FIGURES

[0120] FIG. 1 shows a perspective view of a panel according to a first preferred embodiment of the invention. The layers, which may not all be present, are in order: metal facing A; fire barrier layer (1) B; fire barrier layer (2) C; insulating foam D; metal facing A.

[0121] FIG. 2 shows the method of manufacture of the panel of FIG. 1. FIG. 2(a) shows a cross-section through a mould. FIG. 2(b) shows a plan view of the mould of FIG. 2(a). FIG. 2(c) shows a panel formed using the mould of FIGS. 2(a) and 2(b).

[0122] FIG. 3 shows a method of testing fire resistance properties of the panel of FIG. 1. FIG. 3(a) shows a perspective view of the apparatus and panel. FIG. 3(b) shows the clips used in the apparatus of FIG. 3(a). FIG. 3(c) shows a side view of the apparatus and panel of FIG. 3(a) during testing.

[0123] FIG. 4 shows a side view of a panel including a joint region according to a second preferred embodiment of the invention. The components, which may not all be present, are: metal facing A; standard gasket E; fire barrier layer B; insulating foam D.

[0124] FIG. 5 shows a side view of an arrangement of the panel of FIG. 4 mounted to an adjacent panel.

EXAMPLES

[0125] The invention will be further described with reference to the following non-limiting examples.

[0126] Materials

[0127] Polyurethane/Polyisocyanurate Foam Core

[0128] A bi-component system comprising (A) a polyol including a blowing agent and a catalyst and (B) a polymeric isocyanate PMDI is used for the foam core. Voratherm CN 604 polyol (A) is reacted with a high functional PMDI (B) at index 2.85. Voratherm CN 604 is a commercial product of The Dow Chemical Company.

[0129] Polyurethane/Polyisocyanurate Adhesive Layer

[0130] A bi-component system comprising (A) a polyol added with a catalyst and (B) a polymeric isocyanate PMDI is used for fire barrier layer(s). Voramer MB 3171 polyol (A) is reacted with a 2.7 functionality PMDI (B) at index 2.00. Voramer MB 3171 is a commercial product of The Dow Chemical Company.

[0131] Polyurethane Adhesive Layer

[0132] A bi-component system comprising (A) a polyol (B) a polymeric isocyanate PMDI is used for fire barrier layer(s). Voranol CP 450 polyol (A) is reacted with a 2.7 functionality PMDI (B) at index 1.00. Voranol CP 450 is a commercial product of The Dow Chemical Company.

[0133] Polyurethane/Polyurea Adhesive Layer

[0134] A polyurethane/polyurea adhesive coating is obtained by reacting (A) a sodium silicate solution in water (common name: water glass) and (B) an isocyanate-capped polyurethane (prepolymer). As the (A) part a 37 wt. % sodium silicate solution in water from Sigma-Aldrich Inc. is used; as the (B) part Hypol JM 5002 prepolymer is used. Hypol JM 5002 is a commercial product by The Dow Chemical Company.

[0135] Filler: Ceramifying Composition

[0136] A blend of inorganic minerals known to undergo sintering at high temperature (commercial name: Ceram Polymerik FM3H) is purchased from Ceram Polymerik Ltd. The material, a white, fine powder, is used as received and without any further purification. It is believed to contain ATH/talc/APP.

[0137] Filler: Kaolin Powder

[0138] Kaolin (anhydrous aluminum silicate, Al2Si2O5(OH)4) powder (average particle size 3.8 m) is purchased from READE Advanced Materials. The material is used without any further purification.

[0139] Filler: Portland Cement

[0140] Portland Cement (commercial name: Laterlite Leca CS 1600) is purchased from Laterlite S.p.A. (Milan) and used without any further purification.

[0141] Filler: Silica Aerogel Powder

[0142] A powdered silica aerogel (commercial name: Cabot Nanogel TLD102) is purchased from Cabot Corporation and used without any further purification. The used grade shows relatively broad-size granules (up to 1.2 mm in diameter) having an average density of 80-90 kg/m3.

[0143] Filler: Glass Bubbles

[0144] Hollow glass microspheres are purchased from 3M company. The spheres are commercially available under the trade name of 3M Glass Bubbles S35; their density is 350 kg/m3.

[0145] Filler: Expandable Graphite

[0146] Expandable graphite is obtained from Nordmann Rassmann. The product is commercially available under the trade name of Nord-Min KP 251. It has a mean particle size of 250 m.

[0147] Filler: Glass Fibres

[0148] Chopped glass fibres (25 mm long and 12 m in diameter) are obtained from Hainan Fuwang Industrial Co. Ltd of China.

[0149] Blanket: Silica Aerogel Blanket

[0150] A commercial silica aerogel blanket (commercial name: Cabot Thermal Wrap; thickness: 6 mm) is purchased from Cabot Corporation and used without any treatment. The blanket consists of Nanogel granules within non-woven fibres of polyethylene and polyester.

[0151] Blanket: Mineral Wool Blanket

[0152] A commercial mineral wool blanket (commercial name: Rockwool 234; thickness: 20 mm) is purchased from Rockwool Italia S.p.A. and used without any treatment.

[0153] Procedures

[0154] Mould Setup

[0155] The mould arrangement is shown in FIGS. 2(a) and 2(b).

[0156] In an aluminium mould 10 (303010 cm) having walls thermostatically maintained at 50 C., a 2020 cm steel plate 12 (thickness 0.4 mm; lower steel facing) is centered at 5 cm from the mould walls. Four 201010 cm aluminium spacers 14 are placed on the top of the steel plate 12 and all along the mould borders; a central 101010 cm hole 16 remains in the mould 10.

[0157] Four strips of commercially available adhesive tape 18 are attached parallel to the steel plate 12 at 45 to the edges of the aluminium mould 10 at the upper corners of the central hole 16. Another 1010 cm steel plate 20 (thickness 0.4 mm; upper steel facing) is placed on the taped corners to close the mould 10.

[0158] After 1 hour the temperature of the spacers 14 is checked with a thermocouple; the mould 10 is then closed again until the temperature reaches 50 C. When this temperature is reached, the mould 10 is opened and the upper steel facing 20 is temporarily removed for foam pouring.

[0159] Production of Small-Scale Panels

[0160] FIG. 1 shows a small-scale panel in accordance with the Examples. FIG. 2 summarises the production process.

[0161] The fire barrier layer(s) and the foam core are prepared in the mould. To form the first fire barrier layer B (structural integrity barrier layer or combined structural integrity barrier and thermal barrier layer), the polyol or water glass composition is obtained by hand mixing the components; after the addition of the isocyanate, 40 g of the reaction mixture is quickly poured into the central hole 16 in the mould 10 on top of the lower steel facing 12/A.

[0162] Where a second fire barrier layer C (thermal barrier layer) is to be formed from a liquid reaction mixture, it is prepared in the same way. 40 g of the reaction mixture is poured on top of the first fire barrier layer B in the central hole 16 in the mould 10 no more than 20 s after the pouring of the first fire barrier layer. Alternatively, where a blanket (silica aerogel blanket or mineral wool blanket) is used as the second fire barrier layer, it is gently placed on the top of the first fire barrier layer no more than 20 s after pouring.

[0163] The PU/PIR foam layer D is prepared by hand mixing the components, and pouring the reaction mixture on the top of the fire barrier layer(s). Where the upper fire barrier layer is poured, this should be done within 20 s of pouring.

[0164] After pouring of the foam composition, the upper steel facing 20/A is quickly positioned, and the mould 10 is closed before the PU/PIR foam reaches the upper steel facing 20/A.

[0165] After 10 minutes of reaction, the mould 10 is open and the small-scale panel 22 is removed from the mould (FIG. 2(c)).

[0166] Production of small-scale panel arrangements Small-scale panel arrangements with joint regions (Example 4, FIGS. 4 and 5) are formed from commercially available sandwich panels (PW 1000 from Painel 2000, Portugal). Strips of 10 cm (perpendicular to edge)20 cm (along edge) are taken from the edge portions of each of two sandwich panels. One sandwich panel has a male edge portion 42 and the other sandwich panel has a female edge portion 44. The female edge portion 44 is provided with a PU/PIR foam gasket E.

[0167] The fire barrier material B is formed by hand mixing the components in a cup and pouring the liquid reaction mixture onto the female edge portion 44 of one panel strip. The second panel strip is then immediately placed in position to take advantage of the adhesive properties of the fire barrier material B.

[0168] Thus, a panel arrangement 46 of area 2020 cm is produced (FIG. 5). Two self-threading screws 48 are used at the ends of the joint region 50 to hold the panel arrangement 46 in place. The screws 48 extend through the panel and emerge from the opposite face.

[0169] Characterisation of Fire Resistance Properties of the Small-Scale Panels and Small-Scale Panel Arrangements

[0170] This process is summarised in FIG. 3.

[0171] A small-scale panel 22 is supported on a steel frame 24 (FIG. 3(a)). The frame 24 is in the form of a square platform 26 of size 20 cm20 cm, with a central 10 cm10 cm hole 28, supported on a leg 30 of height 20 cm at each corner. The panel 22 is clipped using at least four metal clips 34 (FIG. 3(b)) to the steel frame (at points X) so that the panel 22 is aligned with the hole 28 in the platform 26. A Bunsen burner 36 is placed under the centre of the lower steel facing 12 (FIG. 3(c)). A first needle thermocouple 38 is positioned in the centre of the panel 22 (i.e. at 5 cm from each face). A second needle thermocouple 40 is contacted with the centre of the lower steel facing 12 and used to verify that the same temperature is reached in all experiments. The temperature over time is monitored from the beginning of the flaming.

[0172] Damage is measured at the end of the trial as damaged height. The small-scale test is used to provide indicative results.

[0173] A similar small-scale fire test is used to test fire barrier materials in the joint regions between panels (Example 4).

[0174] Creation of Panels for Medium-Scale Fire Resistance Test

[0175] 60608 cm sized metal faced sandwich elements are produced. The fire barrier layer(s) are distributed on metal facings using a low pressure foaming machine combined with an air spray mixing head device. The metal facings are then placed in a mould. The PIR reaction mixture is injected into the heated mould using a high pressure foaming machine.

[0176] Characterization of Fire Resistance Properties in the Medium-Scale Test

[0177] The 6060 cm sandwich panels are tested using a furnace capable of following the temperature/time curve of the EN 1363-1 standard. The temperature on the cold side of the sandwich is recorded vs. time in the central position of the surface. The results from the medium-scale test are more reliable than those from the small-scale test.

Examples

Example 1

Structural Integrity Barrier Layer

Example 1-1

[0178] a multilayer sandwich panel as in FIG. 1, where layer B is a polyurethane/polyisocyanurate adhesive layer obtained by reacting Voramer MB 3171 filled with the ceramifying composition Ceram Polymerik FM3H (50 wt. % of the overall composition i.e. layer B as a whole) with a 2.7 functionality PMDI. No C layer is present. Layer D is Voratherm CN 604-based foam.

Comparative Example 1-2

[0179] a sandwich panel as in FIG. 1. Layer D is Voratherm CN 604 polyurethane/polyisocyanurate foam, no fire barriers B or C.

Comparative Example 1-3

[0180] a multilayer sandwich panel as in FIG. 1, where layer B is a polyurethane/polyisocyanurate adhesive layer obtained by reacting Voramer MB 3171 polyol with PMDI isocyanate. No C layer is present. Layer D is Voratherm CN 604-based foam.

Comparative Example 1-4

[0181] a multilayer sandwich panel as in FIG. 1, where layer B is a polyurethane/polyisocyanurate adhesive layer obtained by reacting Voramer MB 3171 filled with kaolin (31 wt. % of the overall composition i.e. layer B as a whole) with a 2.7 functionality PMDI. No C layer is present. Layer D is Voratherm CN 604-based foam.

Comparative Example 1-5

[0182] a multilayer sandwich panel as in FIG. 1, where layer B is a polyurethane/polyisocyanurate adhesive layer obtained by reacting Voramer MB 3171 filled with Portland Cement (31 wt. % of the overall composition i.e. layer B as a whole) with a 2.7 functionality PMDI. No C layer is present. Layer D is Voratherm CN 604-based foam.

Comparative Example 1-6

[0183] a multilayer sandwich panel as in FIG. 1, where layer B is a polyurethane/polyurea adhesive layer obtained by reacting an isocyanate prepolymer (Hypol JM 5002) with waterglass (sodium silicate solution 37.1 wt. % in water). No C layer is present. Layer D is Voratherm CN 604-based foam.

Example 1-7

[0184] a multilayer sandwich panel as in FIG. 1, where layer B is a polyurethane/polyisocyanurate adhesive layer obtained by reacting Voramer MB 3171 filled with chopped glass fibres (25 mm long) (10 wt. % of the overall composition i.e. layer B as a whole) with a 2.7 functionality PMDI. No C layer is present. Layer D is Voratherm CN 604-based foam.

Example 2

Thermal Barrier Layer

Example 2-1

[0185] a multilayer sandwich panel as in FIG. 1, where layer B is a polyurethane/polyisocyanurate adhesive layer obtained by reacting Voramer MB 3171 filled with hollow silica microspheres 3M S35 (18 wt. % of the overall composition i.e. layer B as a whole), with a 2.7 functionality PMDI. No layer C is present. Layer D is Voratherm CN 604-based foam.

Example 2-2

[0186] a multilayer sandwich panel as in FIG. 1, where layer B is a polyurethane/polyisocyanurate adhesive layer obtained by reacting a polyol carrying silica aerogel and isocyanate. As the polyol, Voramer MB 3171 filled with micrometric particles of Cabot Nanogel is used. The silica aerogel content with respect to the dispersed composition (layer B as a whole) is 4.3 wt. %. As an isocyanate, a 2.7 functionality PMDI is used. No layer C is present. Layer D is Voratherm CN 604-based foam.

Example 2-3

[0187] a multilayer sandwich panel as in FIG. 1, where layer B is a polyurethane adhesive layer obtained by reacting a polyol carrying silica aerogel and isocyanate. As a polyol, Voranol CP 450 filled with micrometric particles of Cabot Nanogel is used. The silica aerogel content with respect to the dispersed composition (layer B as a whole) is 3.8 wt. %. As an isocyanate, a 2.7 functionality PMDI is used. No layer C is present. Layer D is Voratherm CN 604-based foam.

Example 2-4

[0188] a multilayer sandwich panel as in FIG. 1, where layer B is a polyurethane/polyisocyanurate adhesive layer obtained by reacting of Voramer MB 3171 polyol with PMDI isocyanate. Layer C is a 1001006 mm Thermal Wrap silica aerogel blanket. Layer D is Voratherm CN 604-based foam.

Example 2-5

[0189] a multilayer sandwich panel as in FIG. 1, where layer B is a polyurethane/polyisocyanurate adhesive layer obtained by reacting Voramer MB 3171 filled with the ceramifying composition Ceram Polymerik FM3H (50 wt. % of the overall composition i.e. layer B as a whole) with a 2.7 functionality PMDI. Layer C is a 1001006 mm Thermal Wrap silica aerogel blanket. Layer D is Voratherm CN 604-based foam.

Example 2-6

[0190] a multilayer sandwich panel as in FIG. 1, where layer B is a polyurethane/polyisocyanurate adhesive layer obtained by reacting Voramer MB 3171 filled with expandable graphite (10 wt. % of the overall composition i.e. layer B as a whole) with a 2.7 functionality PMDI. No C layer is present. Layer D is Voratherm CN 604-based foam.

Comparative Example 2-7

[0191] a multilayer sandwich panel as in FIG. 1, where layer B is a polyurethane/polyisocyanurate adhesive layer obtained by reacting Voramer MB 3171 polyol with PMDI isocyanate. Layer C is a 10010020 mm Rockwool 234-grade mineral wool blanket. Layer D is Voratherm CN 604-based foam.

Example 3

Combined Structural Integrity Barrier Layer and Thermal Barrier Layer

Example 3-1

[0192] a multilayer sandwich panel as in FIG. 1, where layer B is a PU/PIR adhesive layer obtained by reacting Voramer MB 3171 filled with both the ceramifying composition Ceram Polymerik FM3H (40 wt. % of the overall composition i.e. layer B as a whole) and the hollow silica microspheres (11 wt. % of the overall composition i.e. layer B as a whole) with a low functional PMDI. No C layer is present. Layer D is Voratherm CN 604-based foam.

Example 3-2

[0193] a multilayer sandwich panel as in FIG. 1, where layer B is a PU/polyurea polymer layer obtained by reacting an isocyanate prepolymer (Hypol JM 5002) with a waterglass (sodium silicate solution 37.1 wt. % in water) dispersion of micrometric particles of Cabot Nanogel silica aerogel and a surfactant commercially available under the name of Pluronic P105. The silica aerogel content with respect to the dispersed composition (layer B as a whole) is 4 wt. %, while the surfactant is 1.6 wt. %. No C layer is present. Layer D is Voratherm CN 604-based foam.

Example 3-3

[0194] a multilayer sandwich panel as in FIG. 1, where layer B is a PU/PIR adhesive layer obtained by reacting Voramer MB 3171 filled with hollow glass microspheres 3M S35 (18 wt. % of the overall composition i.e. layer B as a whole), with a 2.7 functionality PMDI. Layer C is a 1001006 mm Thermal Wrap silica aerogel blanket. Layer D is Voratherm CN 604-based foam.

[0195] The composition of the panels tested is reported in Table 1 (Example 1) and Table 2 (Examples 2 and 3).

TABLE-US-00001 TABLE 1 Example Comp. Comp. Comp. Comp. Comp. 1-1 Ex. 1-2 Ex. 1-3 Ex. 1-4 Ex. 1-5 Ex. 1-6 Ex. 1-7 PIR foam composition (parts by weight) Voratherm 100 100 100 100 100 100 100 CN 604 polyol Voracor CM 611 4 4 4 4 4 4 4 Catalyst Voranate M 600 171 171 171 171 171 171 171 PMDI Isocyanate n-pentane 12 12 12 12 12 12 12 Fire Barrier composition (parts by weight) Voramer 100 100 100 100 100 MB 3171 polyol Ceram 223 Polymerik FM3H Kaolin 100 Portland Cement 100 Chopped glass 25 fibres Waterglass 100 Hypol JM 5002 47 Isocyanate Voranate M 220 123 123 123 123 123 PMDI Isocyanate Amount of 69 50 50 additive in reactant (wt %) Amount of 50 31 31 additive in fire barrier composition (wt %)

TABLE-US-00002 TABLE 2 Comp. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. 2-1 2-2 2-3 2-4 2-5 2-6 2-7 3-1 3-2 3-3 PIR foam composition (parts by weight) Voratherm 100 100 100 100 100 100 100 100 100 100 CN 604 polyol Voracor CM 611 4 4 4 4 4 4 4 4 4 4 Catalyst Voranate M 600 171 171 171 171 171 171 171 171 171 171 PMDI Isocyanate n-pentane 12 12 12 12 12 12 12 12 12 12 Fire Barrier composition (parts by weight) Voramer 100 100 100 100 100 100 100 100 MB 3171 polyol Voranol CP 450 100 polyol Ceram Polymerik 223 180 FM3H 3M Silica Hollow 50 50 50 Microspheres Cabot Nanogel 10 10 6.25 Expandable 25 graphite Pluronic P105 2.5 Waterglass 100 Hypol JM 5002 47 Isocyanate Voranate M 220 123 123 150 123 123 123 123 123 123 PMDI Isocyanate Thermal Wrap Yes Yes Yes Silica aerogel Blanket Mineral Wool Yes Blanket Amount of 33 9 9 69 20 54.5 (ceram) 5.7 33 additive in 15.1 (hollow reagent (wt %) silica microspheres) Amount of 18 4.3 3.8 50 10 40 (ceram) 4 18 additive in fire 11 (hollow barrier silica composition microspheres) (wt %)

Results of Examples 1 to 3 and Discussion

[0196] The internal temperatures of the samples after 15 and 30 minutes of flaming in the small-scale fire test, along with the height of the internal damage after cutting the foam, are reported in Table 3 (Example 1) and Table 4 (Examples 2 and 3).

[0197] The internal temperatures provide an indication of thermal barrier properties. The damage height provides an indication of structural integrity barrier properties. In the case of each of these variables, low values are desirable.

[0198] The small-scale fire test involves severe conditions because the testing thermocouple is only 5 cm from the flame source. Therefore, the fire barrier effect does not apply for as long as 30 minutes.

TABLE-US-00003 TABLE 3 Temperature Temperature Damage after 15 min after 30 min height Sample ( C.) ( C.) (mm) Ex. 1-1 73 214 62 Comparative 129 200 62 Ex. 1-2 Comparative 108 210 63 Ex. 1-3 Comparative 97 219 66 Ex. 1-4 Comparative 92 236 65 Ex. 1-5 Comparative 77 191 64 Ex. 1-6 Example 1-7 69 206 Not measured

TABLE-US-00004 TABLE 4 Temperature Temperature Damage after 15 min after 30 min height Sample ( C.) ( C.) (mm) Example 68 204 61 2-1 Example 95 209 64 2-2 Example 117 216 68 2-3 Example 69 233 64 2-4 Example 49 156 60 2-5 Comp. 107 245 70 Example 2-7 Example 46 186 61 3-1 Example 49 140 55 3-2 Example 55 160 56 3-3

[0199] The temperature on the cold side of the sandwich exposed to the medium-scale fire resistance test after 15, 30 and 40 minutes is reported in Table 5 (Example 1-1, Comparative Example 1-2, Examples 2-1 and 2-2).

TABLE-US-00005 TABLE 5 Temperature Temperature Temperature after 15 min after 30 min after 40 min Sample ( C.) ( C.) ( C.) Example 1-1 30 78 144 Comparative 42 108 198 Ex. 1-2 Example 2-1 41 60 103 Example 2-2 36 62 99 Example 2-6 45 66 103

[0200] From Tables 3 and 4 it can be seen that where both structural integrity barrier and thermal barrier materials (hybrid or separate) are present (Examples 2-1, 2-5 and 3), very good results are achieved in the small-scale fire test. Temperatures after 15 minutes are in the range of 46 to 69 C. Damage height (where measured) is in the range of 55 to 61 mm. This is compared with a temperature after 15 minutes of 108 C. and a damage height of 63 mm for the control with an unmodified APL (Comparative Example 1-3).

[0201] From Table 3 it can also be seen that a fire barrier including a dispersion of ceramifying composition in PU/PIR as the structural integrity barrier material gave the lowest damage height (62 mm) and gave a lower temperature after 15 minutes (73 C.) than fire barriers using kaolin or Portland cement (Example 1-1 and Comparative Examples 1-4 and 1-5). A low temperature after 15 minutes (69 C.) was also achieved using a fire barrier including a dispersion of chopped glass fibres in PU/PIR as the structural integrity barrier material. Kaolin and Portland cement are used as fillers in WO2006010697.

[0202] From Table 4 it can also be seen that the use of a silica aerogel blanket gave a lower damage height (64 mm) and gave a lower temperature after 15 minutes (69 C.) compared with the use of a mineral wool blanket (Example 2-4 and Comparative Example 2-7).

[0203] From Table 5 it can be seen that hollow silica microspheres (Example 2-1), aerogel (Example 2-2) and a dispersion of expandable graphite in PU/PIR (Example 2-6) provided good performance in the medium-scale fire test. Results at 15 minutes in the medium-scale fire test are less significant than those at 30 and 40 minutes. The Example 2-1 fire barrier was found to delay the insulation failure by about 20 minutes, leading to 1=55 performance (EN test referred to above). Observations of the burnt panels showed a dense, coherent char on the exposed side, with cracks of reduced depth in the PIR foam beneath.

Example 4

Joint Protection

Comparative Example 4-1

[0204] panels with joint region as in FIG. 5, with standard open cell gasket E and no fire barrier layer B.

Example 4-2

[0205] panels with joint region as in FIG. 5, where fire barrier layer B is a polyurethane/polyisocyanurate adhesive layer obtained by reacting Voramer MB 3171 filled with hollow silica microspheres 3M S35 (20 wt. % of the overall composition i.e. layer B as a whole), with a 2.7 functionality PMDI. The fire barrier layer B is applied on the standard gasket E.

Example 4-3

[0206] panels with joint region as in FIG. 5, where fire barrier layer B is a polyurethane/polyisocyanurate adhesive layer obtained by reacting Voramer MB 3171 filled with the ceramifying composition Ceram Polymerik FM3H (50 wt. % of the overall composition i.e. layer B as a whole) with a 2.7 functionality PMDI. The fire barrier layer B is applied directly on the insulating foam of the panel. No gasket E is present.

[0207] The panels are submitted to the modified version of the small scale fire test described above.

[0208] The results of Example 4 are shown in Table 6.

TABLE-US-00006 TABLE 6 Temperature Temperature Temperature at 15 min at 30 min at 40 min Example ( C.) ( C.) ( C.) Comparative 369 437 447 Example 4-1 Example 4-2 255 382 407 Example 4-3 186 403 420

[0209] From Table 6 it can be seen that where a fire barrier layer is included in the joint region (Examples 4-2 and 4-3), good results are achieved in the fire test compared with the results where a fire barrier is not included in the joint region (Comparative Example 4-1).

[0210] Proposed further examples:

Example 4-2

[0211] panels with joint region as in FIG. 5, where fire barrier layer B is a PU/polyurea polymer layer obtained by reacting an isocyanate prepolymer (Hypol JM 5002) with a waterglass (sodium silicate solution 37.1 wt. % in water) dispersion of micrometric particles of Cabot Nanogel silica aerogel and a surfactant commercially available under the name of Pluronic P105. The silica aerogel content with respect to the dispersed composition (layer B as a whole) is 4 wt. %, while the surfactant is 1.6 wt. %. Fire barrier layer B is applied on the standard gasket E.

Example 4-3

[0212] panels with joint region as in FIG. 5, where fire barrier layer B is of the composition used in Example 4-2 but is applied directly on the insulating foam of the panel. No gasket E is present.

Example 4-5

[0213] panels with joint region as in FIG. 5, where fire barrier layer B is of the composition used in Example 4-4 but is applied directly on the insulating foam of the panel. No gasket E is present.

[0214] The panels of the preferred embodiments of the invention make use of a multilayer-multifunction concept to combine structural integrity barrier and thermal barrier properties. Very good fire resistance properties are achieved. The findings can also be applied to joint protection.

[0215] Moreover, the panels of the preferred embodiments of the invention are easy to manufacture. This is an improvement compared with WO2006010697, where the waterglass chemistry is difficult to use in a continuous production process because of lack of adhesion between the waterglass-based and metal layers. The use of PU/PIR in the fire barriers of preferred embodiments of the invention allows good adhesion to the metal facing and to the PIR foam core.

[0216] Whilst the invention has been described with reference to the illustrated preferred embodiments and the Examples, the skilled person will appreciate that various modifications are possible within the scope of the claims.