FIRE PROOFED MEMBRANE AND METHOD FOR FABRICATION OF THE SAME

Abstract

 This publication relates to a method and a fire protective lining or membrane for improving fire resistance of a lining or membrane (10) of a plastic material to be used in association with supporting structures (22), such as for example buildings tunnel walls, wherein a surface of the supporting structure (22) is provided with a thin lining or membrane (10) fixed to the surface by means of bolts, and where the membrane or lining (10) is exposed to the possibilities of open flames or fire on the surface facing the tunnel cavity. A fire protection (15) is added to at least one end edge surface (12) of the lining or membrane (10), the added fire protection (15) being configured in such way that the edge (12) of the lining or membrane (10) is prevented from catching fire when exposed to open flames or a burning object.

Description

Technical Field of the Invention

[0001] The present invention relates to a fire protected lining or membrane of a plastic material to be used in association with supporting structures, such as for example tunnel walls, wherein a surface of the supporting structure is provided with a thin lining or membrane fixed to the surface of the supporting structure by means of bolts, and where the membrane or lining may be exposed to the possibilities of open flames or fire. The invention relates also to a method for improving fire resistance of a lining or membrane of a plastic material to be used in association with supporting structures, such as for example tunnel walls, wherein a surface of the supporting structure is provided with a thin lining or membrane fixed to the surface by means of bolts, and where the membrane or lining is exposed to the possibilities of open flames or fire on the surface facing the tunnel cavity.

Background for the Invention

[0002] When building tunnels, it is of importance to make the tunnel safe. Water and loose rock must be prevented from dropping down into the tunnel, casing hazards for the road-users. Moreover it is also of importance to build tunnels that are heat insulated or at least have a lining or membrane preventing ice, water or rock to drop into the tunnel cavity. Such lining or membrane, possibly also the insulating material used, is made of a plastic material and care must be taken to design a solution that is not prone to fire. Hence, governmental rules and regulations specifies requirements that the lining or membrane used as lining in tunnels must i) withstand flames directed perpendicular on the plane lining surface over a certain period of time, and ii) also withstand flames directed more or less perpendicular on the edge cross sectional surface.

[0003] It should be appreciated that such lining or membrane, subsequent to installation in cross-wise arranged sections in the tunnel is provided with reinforcement on the side facing the tunnel and then coated or covered with concrete. It is therefor a requirement that the lining or membrane to be used in tunnels must meet both these requirements. It should be appreciated that most prior art membranes used meet the requirement i), i.e. they are able to withstand flames directed perpendicular on the plane surface. Few if any of the prior art linings or membrane do, however meet the second requirement, requirement ii), i.e. being able to resist fire when exposed to flames acting perpendicular on the end surface of any of the four edges/overlapping ends.

Summary of the Invention

[0004] In this specification a term "tape" is used. It should be appreciated that the term "tape" shall not be construed in a limiting manner to a tape with or without a adhesive on a surface, but should encompass a profile, for example made of aluminum clipped on to the membrane edges and possibly fixed either by a roller system or a clamping device; a band; a layer of a flame resistant material painted on the ends or extruded onto the ends during extrusion of the lining or membrane, such material for example being a flame resistant or retardant PVC, also including a flame resistant string welded or extruded to/onto the edge of the membrane; or a folded end, all preventing the end surface of the membrane or lining to be exposed directly to fire during periods where such ends may be exposed to open flames or fire. Fire protective and resistant materials including fire protective plastic materials, e.g. fire protective polypropylene or polyethylene compounds/compositions, are well known to the skilled person in the field and are therefore not disclosed in more detail.

[0005] An object of the present invention is to provide a membrane or lining that enhances safety for road-users when travelling through a tunnel.

[0006] Another object of the invention is to reduce the risks of fire propagation in tunnels in case of a burning vehicle or its goods.

[0007] An object of the present invention is to provide a membrane or lining intended to be supported by a building structure that meet all fire protecting requirements listed in governmental rules and regulations.

[0008] Another object of the present invention is to provide a method for establishing enhanced fire protective membranes or linings to be used in fire exposer areas, in particular of thin membranes and linings.

[0009] Another object of the present invention is to provide an expedient and effective method for establishing enhanced fire protection when using membranes or lining made of plastic materials, in particular made of thin plastic materials.

[0010] The objects and advantages are achieved by a method and a membrane or lining as further defined in the independent claims. Variants, options and embodiments of the method and the membrane or lining are defined by the dependent claims.

[0011] According to a first aspect of the present invention it is provided a method for improving fire resistance of a lining or membrane of a plastic material to be used in association with supporting structures, such as for example tunnel walls, wherein a surface of the supporting structure is provided with a thin lining or membrane fixed to the surface by means of bolts, and where the membrane or lining is exposed to the possibilities of open flams or fire on the surface facing the tunnel cavity. In said method a fire protection is added to at least one end edge surface of the lining or membrane, the added fire protection being configured in such way that the edge of the lining or membrane is prevented from catching fire when exposed to open flames or a burning object.

[0012] The advantage of this method is an improved fire protection of the membrane when exposed to flames directed more or less perpendicular on the edge cross sectional surface.

[0013] Both the edge cross sectional surface and a part on both side of the edge cross sectional surface may be provided with the fire protection. Moreover, said part may on both side of the edge cross sectional surface be provided with an uneven surface, for example a number of small height fins, grooves or undulations, either in parallel with the edge or perpendicularly arranged with respect to said edge.

[0014] According to an embodiment, the fire protection may be obtained by attaching a tape along the edge on one or both side. In case the protection is in the form of a single tape, said tape may be folded around the edge cross sectional surface, covering said edge surface. Alternatively, the edge surface is covered by a coating, for example added during the extrusion process.

[0015] According to a second aspect of the present invention it is also provided a fire protected lining or membrane of a plastic material to be used in association with supporting structures, such as for example tunnel walls, wherein a surface of the structure is provided with a lining or membrane fixed to the surface of the supporting structure by means of bolts, and where the membrane or lining may be exposed to the possibilities of open flams or fire, wherein a fire protection with a fire protective surface is arranged at least along one of the edges of the lining or membrane, the fire protective surface covering at least the end surface of the membrane or lining.

[0016] According to one embodiment, both the edge cross sectional surface and a part on both side of the edge cross sectional surface are covered by a fire protection. Said fire protection may be in the form of a tape arranged along the edge on one or both sides.

[0017] According to another embodiment, the protection may be in the form of a single tape which is folded around the edge cross sectional surface, covering said edge surface.

[0018] According to an alternative embodiment, the edge surface may be covered by a coating, preferably an extruded string (18), for example added during the extrusion process.

[0019] In a preferred embodiment, the plastic membrane or lining has a thickness of no more than 5 mm, preferably 3 mm or less, and more preferably between 0.5 mm and 3 mm.

[0020] Said part on both side of the edge cross sectional surface may have an uneven surface, for example a number of small height fins, grooves or undulations, either in parallel with the edge or perpendicularly arranged with respect to said edge, in order to obtain enhanced fixture for the fire protection.

[0021] According to the present invention the fire protection may either be obtained by applying a curing fire protective paint or paste to the at least end surfaces of the membrane or linings; applying a folded tape over the end surface and at least one edge surface portion of the membrane or lining, either by using a tape with glue on one side; obtaining fixing by means of hot air supplied to the tape upstream of a pair of pressure rollers or by means of thermal rollers.

[0022] Alternatively, the tape may be folded around the end surface and affixed to the membrane by means of sewing or stitching. In such case the sewing machine may be connected to the production line for extruding and forming the membrane, the sewing occurring simultaneously with the extrusion and forming of the membrane or lining.

[0023] In the context of the present invention, a "thin" plastic membrane or lining is to be understood as a membrane or lining with a thickness being typically about 5 mm or less, preferably about 3 mm or less, and more preferably in the range of about 0.5 to about 3 mm.

Short Description of the Drawings

[0024] The above and further features of the invention are set forth with particularity in the appended claims and together with advantages thereof will become clearer from consideration of the following detailed description of an exemplary embodiment of the invention given with reference to the accompanying drawings, where:

Figure 1 shows schematically a first step in adding a fire protection to the end surface of a thin membrane or lining;

Figure 2 shows schematically a next step where a fire protection tape is added to the lower part and end surface of a membrane or lining;

Figure 3 shows schematically a second embodiment of the present invention where hot air is applied to the tape in order to obtaining softness and binding with the membrane or lining;

Figure 4 shows schematically an alternative embodiment of the present invention where heat for fixing the tape to the membrane or lining is obtained by means of heated rollers;

Figure 5 shows schematically a vertical section through an end portion of a membrane or lining with fire protection tape;

Figure 6 shows schematically a third embodiment of the present invention where hot air is used to weld a fire protective strip and the edge of the membrane or lining together;

Figure 7 shows schematically a fourth embodiment of the present invention where an extrusion machine is used to extrude a fire protective extrusion strip onto the edge of the membrane or lining;

Figure 8 shows schematically a fifth embodiment of the present invention where a fire protective string is extruded onto the edge of the membrane during its extrusion while the membrane material is still in a melt. The string is extruded by means of a side extruder on the side of the extrusion machine for the membrane.

Figure 9 shows schematically a cross sectional view of a tunnel, showing two membrane sheets assembled and overlapping at the top og the tunnel;

Figure 10 shows schematically a joint between two adjoining membrane or lining ends;

Figure 11 a shows schematically a end view of a lining or membrane, where only the upper half of the membrane edge end is rolled to half the thickness of the remaining part of the membrane; and

Figure 11 b shows an end view of the end view shown in Figure 10a, where the end is folded back and providing an end where the end surface will not be exposed, the end surface being in the form of a bend.

Detailed Description of Embodiments Disclosed in Drawings

[0025] Various aspects of the disclosure are described more fully hereinafter with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed herein, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

[0026] The following description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. Although reference is made to a membrane or lining for tunnels it should be appreciated that the same principle may be applied to membranes or plates suitable for use in building structures where fire protection of the membrane of lining is required.

[0027] Reference throughout the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases "in one embodiment" or "in an embodiment" in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0028] Figure 1 shows schematically a first step in adding a fire protection 11 to the end surface 12 of a thin membrane or lining 10, for example with a thickness in the range of 0.5 mm to 3 mm. According to one embodiment, the thickness of the membrane or lining 10 is reduced along the end or edge surface 12 of the membrane or lining 10. The height h of the edge portion with reduced thickness may for example be in the range of 10 mm to 30 mm, while the part with reduced thickness may have a thickness in the range of 0.5 mm to 1.5 mm. It should be appreciated that a preferred reduction in the thickness may be by twice the thickness of possible fire protective tape 11 to be applied on one side or folded around the end surface 12, covering both the end 12 surface, the reason being to avoid possible build up when rolling the fabricated membrane or lining 10 on rolls (not shown). As indicated in Figure 1, the portion with reduced thickness extends continuously along the entire edge length of the membrane or lining 10. Moreover, such portion with reduced thickness may be continuously provided along both edge surfaces.

[0029] It should be appreciated that the embodiment shown in Figure 1 is suitable for use where the fire protection (not shown) may be in the form of a paste or paint applied to both the end surface 12 and at least one of, but preferably to both of the edge surfaces 13 with reduced thickness.

[0030] The reduction in thickness is obtained by a pair of rollers 14, rotating around parallel axes 14'. The width of the rollers 14 are configured so as to provide a required height h of the portion with reduced thickness.

[0031] Figure 2 shows schematically a second embodiment of the present invention, where rotating rollers 14 are used for folding a fire protective tape 15 around the end surface 12 and also covering the edge surface 13, at least on one side, preferably on both sides of the membrane or lining 10. The reduced thickness portion of the edge surface may be produced in a step by pair of rollers (not shown) upstream of the rollers 14 for folding the tape 15 around the end surface. Alternatively, the portion with reduced thickness may be provided with the same pair of rollers 14 that folds the tape 15 around the end surface 12 to form the fire protection 11 of the end surface 12. The tape 15 may be of a type provided with glue on the surface side intended to face and be in contact with the membrane or lining 10.

[0032] Figure 3 shows schematically a second embodiment of the present invention where hot air is applied to the tape 15 by means of a nozzle 16, receiving hot air from a hot air source (not shown), in order to obtain softness and binding with the membrane or lining 10. The hot air is supplied just upstream of the pair of rollers 14. Apart from this detail the features and properties may be as described in conjunction with Figure 1 or 2.

[0033] Figure 4 shows schematically an alternative embodiment of the present invention where heat for fixing the tape 15 to the membrane or lining 11 is delivered by thermal rollers 17. Otherwise the features, functions, etc., correspond to those of described in connection with Figure 1 or 2.

[0034] Figure 5 shows schematically a vertical section through a part of an end portion of a membrane or lining 10, where the end surface 12 along the entire edge is provided with a portion 13 with reduce thickness and with a tape 15 folded around the end surface 12 by means of rollers 14. In the space or void between the end surface 12 and the fold of the tape 13 a bead or string 18 of a fire resistant material is arranged. The bead or string 18 may be fixed on the tape or band 15 as a continuous, elongate string, configured in such way as to add fire protecting properties to the end surface of the membrane or lining 10.

[0035] In the process of establishing the portion along each longitudinal side of the membrane, such area on one or both sides may be provided with grooves or low height ribs or undulations or the like as part of the rolling process, the purpose and effect of these grooves or ribs being to enhance the adhesion effect of the tape. These ribs, grooves, undulations or the like may either extend in longitudinal direction of the membrane or lining, or be arranged normal to the end surface in question. Such unevenness provides increased exposure area and enhanced fixture for paint or material applied to the contact surface between the membrane ends and applied material. During possible thermal adhesion such uneven surfaces secures also a better fixture of the tape or band to be attached along the membrane edges.

[0036] Figure 6 shows schematically another embodiment of the present invention wherein a fire protective string 18 is heat welded by means of a nozzle 16, receiving hot air from a source 30, to an end surface 12 of the membrane or lining 10, such that the string 18 functions as a fire protective end surface of the membrane or lining. Preferably, the string 18 is thereafter rolled flat (not shown), thereby achieving more or less the same thickness of the membrane or lining. The advantage of this additional step is an improved storage when the fabricated membrane or lining 10 is rolled up. The protected membrane or lining then has the same thickness everywhere and possible build up is avoided when rolling up the said fabricated membrane. The string 18 is preferably made of a fire protective plastic material suitable for thermal welding and compatible to the membrane or lining 10. Preferably, fire protective polyethylene or polypropylene compound/composition is used for the string material. Typical temperatures applied during welding are 500 °C or less depending on the exposure time to the hot air and the type of material used.

[0037] Figure 7 shows schematically another embodiment of the present invention wherein the fire protective string 18 from Figure 6 is extruded onto the end surface 12 of an already produced lining or membrane 10 by means of an extrusion machine 32. The string is thereby typically made from a fire protected plastic material suitable for extrusion, such as compositions based on polyethylene or polypropylene. Typical temperatures used during extrusion are around 200 °C. As described for the embodiment in Figure 6, the attached string can thereafter be flat rolled to obtain the same thickness as the membrane 10.

[0038] Figure 8 shows schematically an alternative embodiment of the present invention wherein the fire protective strip 18 of Figure 7 is applied to the end surface 12 of a membrane 10 during the extrusion process of said membrane 10, when the membrane 10 is still in a melted stage. In the shown example, the string material is supply via a pipe 46, e.g. as pellets or as a string, to a side extruder 42 arranged in or in connection to the die of a membrane extrusion machine 44 used in the extrusion process of the membrane 10. The extruded material is transported further through a channel 48 with a nozzle (not shown) to the end surface 12. The same plastic material as described in Figure 7 may be used for the string 18. Alternatively to extruding the string 8 onto the end surface 12 of the membrane 10 simultaneously with the extrusion of the membrane10, the string may by extruded on the membrane right after the extrusion of the membrane when the membrane is still in a melted stage (not shown). After the extrusion step, the membrane 10 with the extruded string 18 on the end surface 12 is in both alternatives typically further processed by rollers and calendaring (not shown).

[0039] The extrusion machine 44 (die) for the membrane and the side extruder 42 used for extruding of the string 18 may be separated units or form an integrated unit.

[0040] Figure 9 shows schematically a cross sectional view of a tunnel 22, showing two membrane sheets 10 assembled and overlapping by means of a joint 19 at the top og the tunnel 22. The joint is shown in more detail in Figure 10, comprising two adjoining membrane or lining ends, each provided with the protective fire protections 11 according to the present invention. The joint includes a lug 23 on each side of the lining 10 and the ends are welded together along two parallel weld seams 20.

[0041] Figure 11 a shows schematically an end view of a lining or membrane 10, where only the upper half of the membrane edge end 13 is rolled to half the thickness of the remaining part of the membrane 10; while Figure 10b shows an end view of the end view shown in Figure 11 a, where the end is folded back and providing an end configuration where the end surface 12 will not be exposed, the exposed end surface being in the form of a bend 21, enhancing the fire resistance of the membrane.

[0042] It should be appreciated that the membrane 10 at appropriate places may be provided with closable openings for access to the backside of the membrane, or apertures for air ducts or the like. In case such apertures or openings are established in the fabrication yard, the edges of the aperture or opening may be fire protected as indicated above under appropriate working conditions, establishing an adequate end protection. In such case the circumferential end surface of the openings or apertures may also be protected with a fire protection as outlined above. In case the apertures or openings are made in situ in the tunnel, end protections as indicated above must be applied in situ.

Claims

1. Method for improving fire resistance of a lining or membrane (10) of a plastic material to be used in association with supporting structures (22), such as for example tunnel walls, wherein a surface of the supporting structure (22) is provided with a thin lining or membrane (10) fixed to the surface by means of bolts, and where the membrane or lining (10) is exposed to the possibilities of open flames or fire on the surface facing the tunnel cavity,
characterized in that a fire protection (15) is added to at least one end edge surface (12) of the lining or membrane (10), the added fire protection (15) being configured in such way that the edge (12) of the lining or membrane (10) is prevented from catching fire when exposed to open flames or a burning object.

2. Method according to claim 1, wherein both the edge cross sectional surface (12) and a part on both side (13) of the edge cross sectional surface (12) are provided with the fire protection (15).

3. Method according to claim 1 or 2, wherein said part on both side of the edge cross sectional surface (13) is provided with an uneven surface, for example a number of small height fins, grooves or undulations, either in parallel with the edge or perpendicularly arranged with respect to said edge.

4. Method according to one of the claims 1 to 3, wherein the fire protection (15) is obtained by attaching a tape along the edge (12) on one or both side.

5. Method according to claim 4, wherein the protection is in the form of a single tape which is folded around the edge cross sectional surface (12), covering said edge surface (12).

6. Method according to claim 1, wherein the edge surface (12) is covered by a coating, for example added during the extrusion process.

7. Fire protected lining or membrane of a plastic material to be used in association with supporting structures (22), such as for example tunnel walls, wherein a surface of the supporting structure (22) is provided with a thin lining or membrane (10) fixed to the surface of the supporting structure (22) by means of bolts, and where the membrane or lining (12) may be exposed to the possibilities of open flames or fire, characterized i n that a fire protection with a fire protective surface (15) is arranged at least along one of the edges (12) of the lining or membrane (10), the fire protective surface (15) covering at least the end surface of the membrane or lining.

8. Fire protected membrane or lining according to claim 7, wherein both the edge cross sectional surface (12) and a part (13) on both side of the edge cross sectional surface (12) are covered by the fire protection (15).

9. Fire protected membrane or lining according to claim 7 or 8, wherein said part (13) on both side of the edge cross sectional surface (12) have an uneven surface, for example a number of small height fins, grooves or undulations, either in parallel with the edge or perpendicularly arranged with respect to said edge.

10. Fire protected membrane or lining according to one of the claims 7 to 9, wherein the fire protection (15) is in the form of a tape (15) arranged along the edge (12) on one or both sides (13).

11. Fire protected membrane or lining according to claim 10, wherein the protection (15) is in the form of a single tape which is folded around the edge cross sectional surface (12) covering said edge surface (12).

12. Fire protected membrane or lining according to claim 7, wherein the edge surface (12) is covered by a coating, preferably by an extruded string (18), for example added during the extrusion process.

13. Fire protected membrane or lining according to one of the claims 7-12, wherein the plastic membrane or lining has a thickness of no more than 5 mm, preferably 3 mm or less and more preferably between 0.5 mm and 3 mm.

Drawing