Field of the Invention

[0001] The invention pertains to methods of manufacturing multi-layer membranes, and in particular, multi-layer membranes with fire-resistant properties for use in various applications, including for example as roofing and flooring underlayments.

Background of the Invention

[0002] It is known in the art to manufacture multi-layer membranes. The facer and the fire resistant component in existing multi-layer membranes frequently show signs of delamination between the layers. Such delamination of layers has been observed at all stages after the multi-layer membranes are formed, for example during storage, transportation, after installation on a structural support member (e.g., a roof), and during production of the membranes. It is desirable to have methods to achieve multi-layer membranes with fire resistant properties having strong adhesion between the layers, in particular between the facer and the fire resistant component. This is preferable for membranes that are intended for use under extreme climates and/or long outdoor exposures. The present invention is directed to improved methods for making multi-layer membranes with fire-resistant properties for use as underlayments.

Summary

[0003] One aspect of the invention provides a method of manufacturing a multi-layer membrane having a strong adhesion between a facer and a fire resistant component. The facer comprises a water resistant polymeric layer, and optionally a sacrificial anti-slip layer and a support fabric. The fire resistant component comprises one or both of a first fire resistant coating and a second resistant coating, and a carrier layer bonded to the first fire resistant coating or the second fire resistant coating, or between the first and second fire resistant coatings if both coatings are present. The first fire resistant coating comprises a first filler mixed with a first carrier, and the second fire resistant coating comprises a second filler with a second carrier. The method comprises applying the facer to the first fire resistant coating or to the carrier layer if the first fire resistant coating is absent and the fire resistant component comprises only the carrier layer and the second fire resistant coating, applying a middle bonding layer between the facer and the fire resistant component, and heating the membrane at a temperature of between about 90°C and about 130°C for a duration in the range of from about 2 minutes to about 60 minutes. In some embodiments, the membrane may be subjected to a pressure between about 0.5 psi and about 130 psi during the heating step to facilitate the lamination of the layers.

[0004] The facer and the fire resistant component may be formed on separate manufacturing lines. The facer may be formed by an extrusion lamination process. The fire resistant component may be formed by a coating method such as a knife coating method or a dip coating method. In some embodiments, a formed facer is combined with the fire resistant component on the manufacturing line for the fire resistant component. In such embodiments, a formed facer is applied on the first fire resistant coating when the first fire resistant coating is still in molten form, after the first fire resistant coating has been applied on the carrier layer. The first fire resistant coating may be applied on the carrier layer by a knife coating method. The facer and the fire resistant component are then bonded together to form the multi-layer membrane by heating the layers in an oven, and subsequent to the heating step, cooling the membrane, for example by pressing the membrane between a pair of chilled pressure rollers. In such embodiments, the middle bonding layer may be omitted.

[0005] Further aspects of the invention and features of specific embodiments of the invention are described below.

Brief Description of the Drawings

[0006] Exemplary embodiments are illustrated in referenced figures of the drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than restrictive.

[0007] Figure 1A is a schematic diagram of a multi-layer membrane according to an example embodiment. Figure 1B is a schematic diagram of a multi-layer membrane according to another example embodiment. Figure 1C is a schematic diagram of a multi layer membrane according to a further example embodiment.

[0008] Figure 2 is a flow chart illustrating the steps of making the multi-layer membrane according to an example embodiment.

[0009] Figure 3 is a schematic diagram illustrating an example lamination apparatus for making a facer of the multi-layer membrane.

[0010] Figure 4 is a flow chart illustrating the steps of combining the facer and the fire resistant component of the multi-layer membrane on the manufacturing line of the fire resistant component according to an example embodiment.

[0011] Figure 5 is a schematic diagram illustrating an example manufacturing line for combining the facer and the fire resistant component of the multi-layer membrane.

Detailed Description

[0012] The invention provides methods of manufacturing a multi-layer membrane with fire resistant properties. Figures 1A, 1B and 1C are schematic diagrams of example multi layer membranes manufactured using the methods of this invention. The multi-layer membrane 10 has a facer 11 and a fire resistant component 13 bonded to the facer 11. The facer 11 comprises at least a water resistant polymeric layer 12. The fire resistant component 13 comprises one or both of a first fire resistant coating 16 and a second fire resistant coating 28, and a carrier layer 14 bonded to the first fire resistant coating 16 and/or the second fire resistant coating 28. The facer 11 may be bonded to the carrier layer 14 (in embodiments in which the first fire resistant coating 16 is not present as shown in Figure 1C) or to the first resistant coating 16 (in embodiments in which the first fire resistant coating 16 is present as shown in Figures 1A and 1B).

[0013] The water resistant polymeric layer 12 may comprise one or more thermoplastic components to form a water resistant coating, and the coating optionally further includes organic and/or inorganic fillers, colorants, ultraviolet light absorbers, dyes, pigments and other suitable additives. Examples of suitable thermoplastic components include polyolefin such as polypropylene and polyethylene, polyolefin elastomers such as thermoplastic elastomers (TPE), ethylene vinyl acetate (EVA) polymers, and/or acrylic polymers such as resins that include methyl-acrylate or ethylene acrylate based terpolymers (e.g., Lotader®).

[0014] The carrier layer 14 may be made of any thermally resistant materials. Examples of materials suitable for use as the carrier layer 14 include woven (e.g., plain weave, twill weave, or satin weave) or non-woven fiberglass, polyvinyl chloride (PVC), silicone rubber, felt (e.g., carbonized felt), polymeric fleece (e.g., polyethylene terephthalate (PET) fleece), other non-woven polymeric material including fabrics made by a needle-punch process, and fire retardant mats (e.g., an expandable graphite mat).

[0015] The first fire resistant coating 16 includes a first filler 24 mixed with a first carrier 26. The second fire resistant coating 28 has a second filler 30 mixed with a second carrier 32. The second filler 30 and the second carrier 32 may comprise the same composition as, or different compositions from the first filler 24 and the first carrier 26 respectively. The second fire resistant coating 28 may be applied on a surface of the carrier layer 14 opposite to the first fire resistant coating 16.

[0016] The first and second fillers 24, 30 are made of substances with fire resistant properties. The first and second fillers 24, 30 may comprise any inorganic and/or organic fillers, such as an intumescent substance, such as expandable graphite, ammonium polyphosphate (APP), melamine (MEL), boric acid, bisphenol A (BPA), polyamide amine, titania, clay, silica, fumed silica, alumina (AI2O3), aluminum trihydrate-ATH (Al (OH)3), and combinations thereof. The first and second carriers 26, 32 may be any materials suitable for binding the first and second fillers 24, 30. The first and second carriers 26, 32 may be an organic or inorganic material, such as polyvinyl chloride (PVC), silicone, acrylic, polyurethane, ethylene propylene diene monomer rubber (EPDM rubber), ethylene-vinyl acetate (EVA) or epoxy carriers or resins. A filler content in the first and second fire resistant coatings 16, 28 may be in the range of from about 20% to about 80% by weight, and a carrier content may be in the range of from about 20% to about 80%. In an example embodiment, the first and second fire resistant coatings 16, 28 comprise 60% by weight of expandable graphite as the fillers 24, 30, and 40% by weight of an acrylic binder as the carriers 26, 32. The onset temperature of the first and/or second filler 24, 30 is at least 160°C, in the range of from about 180°C to about 200°C.

[0017] The multi-layer membrane 10 may include a middle bonding layer 36 arranged between the facer 11 and the fire resistant component 13. The middle bonding layer 36 binds the facer 11 to the fire resistant component 13. The middle bonding layer 36 may comprise a polymeric material such as a thermoset or a thermoplastic to form a pressure sensitive adhesive (i.e., an adhesive that forms a bond when pressure is applied to bond the adhesive with a surface) or a temperature sensitive adhesive (i.e. , an adhesive which is activated by heat). In some embodiments, the middle bonding layer 36 is made from butyl rubber or rubber modified asphalt (bitumen). Alternatively, the middle bonding layer 36 is made from a polymeric bonding layer such as ethylene-vinyl acetate (EVA), Lotader™, thermoplastic elastomers (TPE), and/or thermoplastic polyolefin (TPO).

[0018] In some embodiments, the facer 11 also comprises a support fabric 34, arranged between the water resistant polymeric layer 12 and the middle bonding layer 36.

In embodiments in which the fire resistant component 13 includes only the carrier layer 14 and the second fire resistant coating 28 (i.e., without the first fire resistant coating 16), the facer 11 preferably includes the support fabric 34 to facilitate the binding of the facer 11 to the carrier layer 14. The support fabric 34 stabilizes the adhesion of the water resistant polymeric layer 12 to the middle bonding layer 36. The support fabric 34 can be any suitable materials that can provide reinforcement to the membrane 10, such as a woven (e.g., plain weave, twill weave, or satin weave) or non-woven scrim or mat such as a lay-up fabric. Examples of suitable materials that can be used to form the support fabric 34 include fiberglass, polyolefin such as polypropylene (PP) or polyethylene (PE), and polyester such as polyethylene terephthalate (PET).

[0019] In some embodiments, the facer 11 also comprises a sacrificial anti-slip layer 20 bonded to an outer surface 18 of the water resistant polymeric layer 12 such that the anti slip layer 20 becomes the top layer that is arranged to be exposed to the environment. As used herein, a “sacrificial layer” means that the layer can be removed or omitted without affecting the functionality of the membrane. The anti-slip layer 20 may include a non-woven polymeric layer, combined with colorants, ultraviolet light absorbers, dyes, pigments and other suitable additives such as other anti-slip additives (e.g., thermoplastic polyolefin (TPO), thermoplastic elastomers (TPE), ethylene-vinyl acetate (EVA), Reptyle FX™, foaming agents, calcium carbonate (CaCOs), sand, and lace coating) and fire resistant additives. The non-woven polymeric layer of the anti-slip layer 20 can be any suitable polymer, including for example polyolefin such as polypropylene and polyethylene, polyolefin elastomers such as thermoplastic elastomers (TPE), and polyesters such as polyethylene terephthalate (PET).

[0020] The outer surface 21 of the facer 11 may be the outer surface 18 of the water- resistant polymeric layer 22 (in embodiments in which the anti-slip layer 20 is not present), or an outer surface 22 of the anti-slip layer 20. The outer surface 21 may be smooth, or may be chemically and/or mechanically modified to provide slip resistance properties.

[0021] The multi-layer membrane 10 may have self-adhesive properties such that the membrane may be installed on a surface of a structural support member (e.g., a roof) without mechanical attachment means. In such embodiments, the multi-layer membrane 10 includes a back bonding layer 38 applied to a surface of the bottommost layer 40 of the fire resistant component 13 opposite to the water resistant polymeric layer 12 or the anti-slip layer 20. The bottommost layer 40 of the fire resistant component 13 may be the carrier layer 14 or the second resistant coating 28. The back bonding layer 38 may have the same composition as, or different compositions from the middle bonding layer 36.

[0022] A release liner 42 is releasably attached to the back bonding layer 38 for protecting the back bonding layer 38 until use. The release liner may be made of paper, polyolefins such as polypropylene (PP) or polyethylene (PE), or polyester such as polyethylene terephthalate (PET). One or both sides of the release liner may be coated with a release coating composition containing for example silicone.

[0023] The methods of the invention involve manufacturing a multi-layer membrane (such as the multi-layer membranes 10 shown in Figures 1A, 1B and 1C) which has strong adhesion between the multiple layers such that the membrane can withstand a wide range of temperatures (e.g., at temperatures between about -20°C and about 150°C) in particular during storage and transport, and/or long periods of outdoor exposure without showing signs of delamination between the layers. Some aspects of the invention involve methods for obtaining strong adhesion between the facer 11 and the fire resistant component 13 of the multi-layer membrane 10.

[0024] Referring to Figure 2, the method 100 of manufacturing the multi-layer membrane 10 comprises providing a fire resistant component 13 (block 102) and a facer 11 (block 104), and applying the facer 11 onto the fire resistant component 13, either on the first resistant coating 16 or the carrier layer 14. The facer 11 and the fire resistant component 13 may be made in separate manufacturing lines, such that they are combined to form the multi-layer membrane 10 after the facer 11 and the fire resistant component 13 are in their respective rigid states to allow for sufficient physical bonding to hold the structures in place. Alternatively, the facer 11 may be combined with the fire resistant component 13 on the manufacturing line for the fire resistant component 13 during the process of making the fire resistant component 13.

[0025] The fire resistant component 13 may be formed by coating one or both surfaces of the carrier layer 14 with the fire resistant coatings 16, 28 which are provided in their molten states. Fire resistant coatings 16, 28 may be applied on the carrier layer 14 by a knife coating method or a dip coating method. For example, the knife coating method involves coating one or both surfaces of the carrier layer 14 with an amount of the fire resistant coatings 16, 28, removing, using a knife, an excess amount of the fire resistant coating 16, 28 while the fire resistant coating 16, 28 is still in a molten state so as to obtain a desired thickness of the fire resistant coating 16, 28, and drying the fire resistant component 13, for example, in an oven. An excess amount of coating means an amount of coating greater than the amount required to obtain a desired thickness on the carrier layer 14. The thickness of the coating is determined by the gap size between the knife and the coating. The dip coating method may involve dipping the carrier layer 14 into the molten fire resistant coatings 16, 28, and drying the fire resistant component 13, for example, in an oven.

[0026] The facer 11 may be formed by an extrusion lamination process. Figure 3 illustrates a schematic diagram of an example laminating apparatus 150 used to form the facer 11. The laminating apparatus 150 includes one or more master rolls 151 , 153 each containing a rolled sheet of material and an extruder 156 for forming the extruded material.

A pair of pressure rollers 158, 160 may be arranged downstream of the extruder 156 for pressing the layers together for lamination to form the facer 11.

[0027] Figure 3 illustrates an example lamination apparatus for making a three layer facer 11 comprising the anti-slip layer 20, the water resistant polymeric layer 12 and the support fabric 34. The water resistant polymeric layer 12 is extruded in a molten state from the extruder 156 by feeding a resin into the extruder 156. The water resistant polymeric layer 12 is extruded between the anti-slip layer 20 and the support fabric 34. The three layer facer 11 is pressed together between a pair of pressure rollers 158, 160, which one or both may be chilled, causing the lamination of the anti-slip layer 20 and the support fabric 34 to the water resistant polymeric layer 12. The molten water resistant polymeric layer 12 may be impregnated into the support fabric 34 as the anti-slip layer 20 is being laminated to the support fabric 34. The impregnation of the molten water resistant polymeric layer 12 into the support fabric 34 increases cohesion between the layers of the facer 11, by securing the placement of the support fabric 34 therein, preventing the likelihood of shrinkage and/or expansion of the facer 11 , thereby reduces the likelihood of delamination between the layers.

[0028] To form a two layer facer comprising the water resistant polymeric layer 12 and the support fabric 34, the water resistant polymeric layer 12 is extruded from the extruder 156 and is applied on the support fabric 34. The two layer facer 11 is then pressed together between the pressure rollers 158, 160, one or both of which may be chilled, for lamination.

[0029] Referring to block 106 of Figure 2, in one embodiment, the middle bonding layer 36 is applied on a surface of the formed facer 11. In another embodiment, the middle bonding layer 36 is applied on a surface of the fire resistant component 13, either on the first fire resistant coating 16 (to produce the multi-layer membrane shown in Figure 1A or 1B) or the carrier layer 14 (to produce the multi-layer membrane shown in Figure 1C). The middle bonding layer 36 is arranged to adhere the facer 11 to the fire resistant component 13.

[0030] In some embodiments, the facer 11 comprises only the water resistant polymeric layer 12 (i.e. , the multi-layer membrane 10 has a one layer facer). In such embodiments, the water resistant polymeric layer 12 may be applied directly on the middle bonding layer 36 using an extrusion lamination process. In one example, the process involves simultaneously extruding the molten water resistant polymeric layer 12 and the molten middle bonding layer 36 from a first extruder and a second extruder respectively. In another example, the process involves using a single extruder comprising two hoppers, each extruding one of the molten water resistant polymeric layer 12 and the molten middle bonding layer 36. In a further example, the molten water resistant polymeric 12 and the molten middle bonding layer 36, which have the same composition, are extruded from the same hopper of an extruder. The water resistant polymeric layer 12 and the middle bonding layer 36 are then pressed together between the pressure rollers 158, 160, one or both of which may be chilled, for lamination. The water resistant polymeric layer 12 and molten middle bonding layer 36 may comprise the same composition, or different compositions.

[0031] In some embodiments, the one layer facer 11 comprising only the water resistant polymeric layer 12 may be applied directly on the fire resistant component 13 without the middle bonding layer 36 applied therebetween by extrusion coating the molten water resistant polymeric layer 12 onto the fire resistant component 13 which is in a rigid state.

[0032] In embodiments in which the first fire resistant coating 16 is not present in the fire resistant component 13 (as shown in Figure 1C), the method involves adhering the facer 11 on the carrier layer 14 after applying the middle bonding layer 36 on the facer 11 or the carrier layer 14.

[0033] One of both of the pressure rollers 158, 160 may comprise a matte or glossy coating applied thereon, so that the coating may be applied on the surface of the facer 11 as the facer 11 is pressed between them. One or both of the pressure rollers 158, 160 may also have a surface with a texture formed of a plurality of features that are raised (e.g., protrusions) and/or sunken (e.g., depressions), so as to provide the desired embossed inverse texture on the facer 11 to provide slip resistance.

[0034] The multi-layer membrane 10 may be subjected to a thermal bonding step after the middle bonding layer 36 is applied and pressed between the facer 11 and the fire resistant component 13 (block 108), The middle bonding layer 36 may be cooled to dry before the thermal bonding step. Referring to Figure 2, the thermal bonding step may involve heating the membrane 10 at a temperature in a range of from approximately 90°C to approximately 130°C, fora drying period of from approximately two minutes to approximately 60 minutes. The multi-layer membrane 10 may for example be heated in an oven. The temperature may be maintained constant or varied during the heating step. For example, the temperature may be increased stepwise during the heating step so that the membrane 10 is exposed to increasing temperatures. Alternatively, the membrane 10 may be conveyed through an oven with a plurality of heating zones which are set at different, and increasing, temperatures. The membrane 10 may be subjected to a pressure in the range of from 0.5 psi to 130 psi during the heating step so as to facilitate the lamination.

The membrane 10 is then cooled to room temperature, between about 20°C and about 30°C. The membrane 10 may optionally be subjected to a pressure in the range of from 0.5 psi to 130 psi during the cooling step. The cooling may for example be facilitated by pressing the membrane 10 through a pair of chilled rollers under pressure. The membrane 10 may be cooled for at least 20 minutes.

[0035] The heating of the membrane 10 transitions the middle bonding layer 36 from a solid state to a molten state, strengthening the lamination between the facer 11 and the fire resistant component 13, thereby reducing the likelihood of delamination of the layers. In some embodiments, the middle bonding layer 36 is partially impregnated into the adjacent layer of the facer 11 , such as the support fabric 34 in embodiments in which the support fabric 34 comprises an open-weave fabric such as felt and a non-woven scrim, e.g. fiberglass scrim.

[0036] In some embodiments, the facer 11, in its rigid state, is combined with the fire resistant component 13 in the manufacturing line of the fire resistant component 13. Figure 4 is a flow chart illustrating the steps 200 of combining the facer 11 and the fire resistant component 13 on the manufacturing line of the fire resistant component 13. Figure 5 illustrates an example manufacturing line 162 of the fire resistant component 13. Referring to Figures 4 and 5, the first fire resistant coating 16, which is in molten form, is applied on the carrier layer 14 of the fire resistant component 13. Excess molten fire resistant coating 16 is removed using a knife 166 to obtain a desired thickness of the coating on the carrier layer 14 (block 202). The facer 11 is applied on the first fire resistant coating 16 when the coating is still in molten form (block 204). The facer 11 and the fire resistant component 13 are then pressed between two pressure rollers 164, 166, one or both of which may be chilled, before being subjected to a thermal bonding step, such as by heating the layers in an oven 168, to form the multi-layer membrane 10 (blocks 206, 208). The multi-layer membrane 10 may be heated at a temperature in the range of from approximately 20°C to approximately 190°C for a period in the range of from approximately 2 minutes to approximately 30 minutes. The temperature may be maintained constant throughout the heating step. Alternatively, the temperature may vary during the heating step. A plurality of heating zones, set at increasing temperatures from an input end 170 to an output end 172 of the oven 168, may be provided within the oven 168 along a longitudinal axis of the oven 168. During the heating step, the multi-layer membrane 10 is heated at increasing temperatures as it is being conveyed within the oven 168. In an example embodiment, the oven 168 comprises seven heating zones, set at increasing temperatures in a range of from approximately 20°C to approximately 190°C between the input 170 and output 172 ends. After exiting at the output end 172, the multi-layer membrane 10 is conveyed through the oven 168 at a speed in a range of approximately 2 meters per minute to 10 meters per minute. The multi-layer membrane 10 is cooled after heating (block 210), for example, by pressing the membrane 10 between a pair of chilled rollers 174, 176. Additional pairs of chilled rollers may be arranged downstream of the chilled rollers 174, 176 to further cool the membrane 10.

[0037] Referring to Figure 2, the method 100 of manufacturing the multi-layer membrane 10 optionally includes applying the back bonding layer 38 on the bottommost layer 40 of the fire resistant component 13 (block 110), and applying the release liner 42 to the back bonding layer 38 (block 112) to form a self-adhesive multi-layer membrane 10.

[0038] The method of this invention includes applying and laminating additional layers together to further strengthen the membrane 10. For example, the facer may include more than three layers. The lamination process in Figure 3 may include more than two master rolls containing sheets of materials to combine with the extruded material.

EXAMPLES

Example 1: Multi-layer Membranes with the Middle Bonding Layer

[0039] Self-adhesive multi-layer membranes 10 with nine layers of the type depicted in Figure 1A were made using different compositions as the middle bonding layer 36. The different compositions are: 1) an adhesive composition comprising a synthetic rubber based hot melt pressure sensitive adhesive with a weight of 200 gsm, 2) butyl rubber adhesive with a weight of 400 gsm, 3) a polymer bonding layer sold under the name Lotader™ 4513T with a weight of 150 gsm, and 4) a polymer bonding layer sold under the name Ateva™

1941 with a weight of 140 gsm. The lamination strength between the facer 11 and the fire resistant component 13 (Ibs/ft) was measured after the membranes have been subjected to different thermal bonding conditions, and the control membranes without being subjected to a thermal bonding step. The lamination strength was tested by a method comprising the steps of delaminating a section of the facer 11 and the fire resistant component 13, and clamping the delaminated section of the layers of the facer 11 and the fire resistant component 13 to run a peel adhesion strength test at a test speed of about 50 mm/min in accordance with ASTM D1970. Three measurements were taken for each condition, and the values presented in Table 1 is the average number of the three measurements.

Table 1. Comparison of the strength of adhesion of the facer to the fire resistant component under different thermal bonding conditions

Example 2: Multi-layer Membranes with the Facer applied on the Fire Resistant Component on the Manufacturing Line of the Fire Resistant Component [0040] A self-adhesive multi-layer membrane 10 was produced using the steps illustrated in the flowchart in Figure 4 and the fire resistant component manufacturing line illustrated in the schematic diagram of Figure 5. The multi-layer membrane 10 is made of a facer 11 comprising a non-woven fabric with a weight of 65 gsm, bonded to a fire resistant component 13 made of a carrier layer 14 comprising a fiberglass scrim with a weight of 630 gsm and a molten first fire resistant coating 16 comprising 60% by weight of expandable graphite and 40% by weight of an acrylic binder. The non-woven fabric of the facer 11 was laminated directly onto the first fire resistant coating 16. The facer 11, first fire resistant coating 16 and carrier layer 14 were heated in an oven at a temperature of about 80°C for about five minutes and then cooled for about 20 minutes. The lamination strength between the facer 11 and the fire resistant component 13 was then measured. The average lamination strength calculated from three measurements was 29.2 Ibs/ft.

Example 3: Multi-layer Membranes with the Facer Combined with the Fire Resistant Component on the Manufacturing Line of the Fire Resistant Component

[0041] A self-adhesive multi-layer membrane 10 was produced using the steps illustrated in the flowchart in Figure 4 and the fire resistant component manufacturing line illustrated in the schematic diagram of Figure 5. The multi-layer membrane 10 is made of a facer 11 comprising a non-woven fabric with a weight of 65 gsm and a polymeric coating layer with a weight of 25 gsm, the facer 11 being bonded to a fire resistant component 13 made of a carrier layer 14 comprising a fiberglass scrim with a weight of 630 gsm and a molten first fire resistant coating 16 comprising 60% by weight of expandable graphite and 40% by weight of an acrylic binder. The polymeric coating layer of the facer 11 was laminated directly onto the first fire resistant coating 16. The facer 11, first fire resistant coating 16 and carrier layer 14 were heated in an oven at a temperature of about 80°C for about five minutes and then cooled for about 20 minutes. The lamination strength between the facer 11 and the fire resistant component 13 was then measured. The average lamination strength calculated from three measurements was 24.8 Ibs/ft.

[0042] Throughout the foregoing description and the drawings, in which corresponding and like parts are identified by the same reference characters, specific details have been set forth in order to provide a more thorough understanding to persons skilled in the art. However, well known elements may not have been shown or described in detail or at all to avoid unnecessarily obscuring the disclosure. [0043] As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the scope thereof. Accordingly, the description and drawings are to be regarded in an illustrative, rather than a restrictive, sense.