Classifications

• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62C—FIRE-FIGHTING
  • A62C2/00—Fire prevention or containment
  • A62C2/06—Physical fire-barriers
  • A62C2/065—Physical fire-barriers having as the main closure device materials, whose characteristics undergo an irreversible change under high temperatures, e.g. intumescent
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K21/00—Fireproofing materials
  • C09K21/02—Inorganic materials
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere
  • C09K3/10—Materials in mouldable or extrudable form for sealing or packing joints or covers
• • E—FIXED CONSTRUCTIONS
  • E04—BUILDING
  • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
  • E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
  • E04B1/62—Insulation or other protection; Elements or use of specified material therefor
  • E04B1/92—Protection against other undesired influences or dangers
  • E04B1/94—Protection against other undesired influences or dangers against fire
  • E04B1/948—Fire-proof sealings or joints
• • E—FIXED CONSTRUCTIONS
  • E06—DOORS, WINDOWS, SHUTTERS, OR ROLLER BLINDS IN GENERAL; LADDERS
  • E06B—FIXED OR MOVABLE CLOSURES FOR OPENINGS IN BUILDINGS, VEHICLES, FENCES OR LIKE ENCLOSURES IN GENERAL, e.g. DOORS, WINDOWS, BLINDS, GATES
  • E06B5/00—Doors, windows, or like closures for special purposes; Border constructions therefor
  • E06B5/10—Doors, windows, or like closures for special purposes; Border constructions therefor for protection against air-raid or other war-like action; for other protective purposes
  • E06B5/16—Fireproof doors or similar closures; Adaptations of fixed constructions therefor
  • E06B5/164—Sealing arrangements between the door or window and its frame, e.g. intumescent seals specially adapted therefor

Definitions

• the present invention relates to a seal having intumescent properties.
• the seal in question is intended to be mounted on fixed frames of fire-breaker dividing elements or fixtures so as to restrict the spread of fire.
• novel system according to the present invention is particularly suitable for use for the manufacture of internal dividing walls and movable fixtures, such as doors, windows, French windows, skylights, portholes or the like.
• the current trend in the fire prevention sector is that of containing outbreaks of fire within closed spaces with the twofold object of preventing the fire from spreading into areas not yet attacked by the fire and of suffocating the fire at its outbreak by restricting the entry of the comburent air needed to fuel it.
• all the communicating fixtures in the environments to be isolated are made of heat and fire-resistant material.
• the resistance of fixtures to fire is measured according to regulations.
• said regulations envisage heating one side of the fixture according to a predefined cycle and measuring at the same time the increases in temperature detected on the opposite side.
• dividing elements comprising a supporting structure formed by elongated elements, which are joined together integrally, and flat buffer panels fixed thereto.
• Said dividing elements may be of the fixed type, for example internal dividing walls, or may comprise a fixed part or frame and an openable, movable part, which is operatively connected thereto by means of hinges, such as, for example, doors, windows, portholes, skylights or the like.
• the elongated elements are generally made of metal - typically aluminium - obtained by means of extrusion, or are in the form of sections or box-shaped elements - typically made of steel - obtained by bending and welding metal sheets.
• the elongated elements may also be made of extruded plastic material which is rigid at normal working temperatures, such as PVC.
• all the elongated elements are shaped so as to obtain cross-sections which have a high moment of inertia and contain cavities which extend in the direction of their length. Some of said cavities communicate with the outside, others are completely enclosed inside the section and are not visible from the outside.
• the flat buffer panels may also be opaque or transparent, these latter being formed by stratified elements comprising several superimposed sheets of transparent material, for example glass, with, arranged in between, a material - also transparent and with intumescent characteristics - intended to join together the individual sheets.
• intumescence is understood as referring to the property of a material to form a large-volume insulating foam when it is subjected to high temperatures. By retaining gas inside it, said foam, which is solidified and partially ceramicized, increases resistance to the transmission of heat both by means of conduction and irradiation and, moreover, retains any cracked parts.
• a drawback of said known embodiments is posed by the high thermal conductivity of the metal structure: the temperatures on the side not exposed to the fire quickly reach values in excess of those required by the regulations.
• the metal structure deforms under the effect of the heat coming from just one side, causing the opening of cracks into which air may pass, which further fuels combustion, or through which the fire may spread to adjacent areas.
• the frame may be totally destroyed by the fire.
• elongated elements made of refractory material, which retains significant residual mechanical properties even when exposed to flame temperatures, are associated with the elongated elements which form the frames of the fixtures.
• WO9707315 describes frames comprising suitably shaped rigid bars which are made of calcium silicate and are inserted into the internal longitudinal cavities of the sections which form the frames.
• calcium silicate a refractory material, retains a rigidity which is able to prevent deformation of the metal and ensure that the fixture remains intact for longer.
• the speeds of the increase in the temperatures measured on the side not exposed to the fire are lower.
• a drawback of said known embodiment consists in the rigidity of the refractory element which must be preconstructed with a cross-section suitably shaped so as to be associated with the metal section and which must be inserted into and associated with it before the construction of said fixture; consequently, during construction of the fixture, it is also required to cut, together with the section, the refractory element included therein and associated therewith, a difficult operation which creates a large quantity of irritating dust and premature wear of the cutting element.
• a fixture according to said prior art may be preconstructed in the workshop but the product obtained is extremely heavy and, in the case where suitable mechanical lifting means cannot be used, transportation, positioning and installation are not easy.
• Seals which are based on the intumescent property of suitably treated graphites, present in mixtures also comprising thermoplastic polymers, flame retardants, inorganic fillers, and ceramicizing agents, are known for sealing cracks in fire- breaker structures.
• Italian Patent application VI2000A000272 describes a seal of the abovementioned type containing inside it a reinforcing mesh made of metal or a composite material.
• the mechanical support for the seals of the abovementioned type may also be obtained by means of a tubular-shaped external sheath having the intumescent mixture inserted inside it.
• Patent application EP 1132563 describes a sealing strip obtained by means of the extrusion of a mixture, which comprises thermoplastic polymers, treated graphite, flame retardants and an inorganic additive capable of forming a ceramic material at working temperatures, inserted into a triple sheath made of a thermoplastic polymer, again obtained by means of extrusion, with added flame retardants.
• a drawback of said known seals consists in their high thermal conductivity, due mainly owing to the presence of graphite, which leads to temperatures in excess of the values required by the regulations being reached quickly.
• GB 2092214 describes a seal, to be associated with the elongated metal elements which form the structure of the fixture, formed by an external part made of rigid PVC and an internal part which has intumescent characteristics and is made of solid hydrated sodium silicate, said seal comprising all the characteristic features according to the preamble of Claim 1.
• a drawback of said known seal consists in the rigidity of the constructional form, which must necessarily be shaped with a cross-section such that it can be associated with the section.
• Another drawback consists in the purely thermoplastic nature of the external part which forms a sheath and which has the sole function of protecting the sodium silicate from the action of the air.
• a further drawback resides in that the solid hydrated sodium silicate is a friable solid which is not suitable for being deformed and undergoing elasto-plastic deformations, which are typical in use as a seal.
• the main object of the present invention is therefore that of overcoming all the drawbacks of the abovementioned prior art by providing an intumescent seal which is provided with a suitable resistance to mechanical stresses, in particular as a result of fire phenomena, and is obtained by means of an alternative solution to those described above.
• Another object of the present invention is that of providing an intumescent seal which may be associated with a fixture after the construction thereof.
• Another object of the present invention is that of providing an intumescent seal with notable thermal insulation properties.
• Another object of the present invention is that of providing a seal which may be easily associated with preconstructed fixtures by adapting its shape to the profiles of the cavities of the elongated metal elements.
• Yet another object of the present invention is that of providing a seal having predefined expansion and heat resistance characteristics according to the design.
• a further object of the present invention is that of providing an intumescent seal which is constructionally simple and totally reliable from an operational point of view.
• an intumescent seal which may be inserted in seats in frameworks or frames of fixtures, in particular of the fire- breaker type, comprising:
• an intumescent mixture M which is capable of expanding under the effect of heat and may be inserted inside said containing chamber C of said sheath G; characterized in that said intumescent mixture M comprises an aqueous solution of alkali metal polysilicate and colloidal silica dispersed in water.
• the alkali metal polysilicate is selected from within the family which comprises sodium polysilicate, potassium polysilicate, lithium polysilicate or mixtures thereof, the intumescent mixture M, which may be inserted inside said sheath G, has a molar ratio, SiO 2 /Me 2 O, of between 3 and 6 and is preferably close to 4.5 and the water content of said intumescent mixture M is between 40% and 65% and is preferably close to 60% by weight.
• a further aspect of the invention envisages a method for the manufacture of an intumescent seal according to Claims 1 to 15, which comprises the following operative steps: a) provision of a substantially tubular sheath G which defines a containing chamber C; b) preparation of an intumescent mixture M which is capable of expanding under the effect of heat; c) degassing of said intumescent mixture M with the extraction of at least one part of water in the vapour phase; d) filling of said containing chamber C with said intumescent liquid mixture
• intumescent mixture M characterized in that the preparation of said intumescent mixture M is performed by means of a step e) involving mixing in a container an aqueous solution of alkali metal polysilicate with colloidal silica dispersed in water.
• a further aspect of the invention envisages a plant for implementing the method according to one or more of Claims 16 to 18, comprising:
• - retaining means 11 intended to support a sheath G which is substantially tubular and has a containing chamber C, so as to keep a top end thereof open;
• - mixing means comprising at least one container 12 for mixing an aqueous solution of alkali metal polysilicate and colloidal silica dispersed in water so as to form an intumescent liquid mixture M;
• said mixing means comprise means for introducing an aqueous solution of alkali metal polysilicate with colloidal silica dispersed in water into said container 12.
• FIGS. 1 to 5 show cross-sections of a few examples of embodiment of an intumescent seal according to the invention
• FIGS. 6 and 7 show a schematic perspective view of another embodiment
• FIG. 8 shows a functional diagram of a mode of implementation of the method for manufacturing the intumescent seal which forms the subject of the present invention.
• Fig. 1 shows, by way of example, a possible embodiment of the seal according to the present invention denoted in its entirety by the number 1.
• the seal comprises an external sheath G, which is made of thermoplastic material and defines a containing chamber C, and an intumescent mixture M which is inserted inside the chamber C.
• the intumescent mixture M comprises alkali metal polysilicate and colloidal silica.
• Alkali metal polysilicate has a fairly complex structure which is normally represented in the form xSiO 2 -yMe 2 O zH 2 O, in which xSiO 2 denotes the silicic acid component, yMe 2 O denotes the basic component of the alkali metal oxide, generally lithium, sodium or potassium, and zH 2 O denotes the hydration water.
• the type of polysilicate is defined by means of the molar or weight ratio, SiO 2 /Me 2 O, between the silica content and oxide content of the alkali metal.
• alkali metal polysilicate will be used to denote a compound of the type indicated above having a molar ratio, SiO 2 /Me 2 O, of between 1.5 and 25.
• the hydrated alkali metal polysilicate has the form of a friable solid.
• the liquid mixture M is obtained by mixing a solution of hydrated alkali metal polysilicate and colloidal silica dispersed in water and has a molar ratio, SiO 2 /Me 2 O, of between 3 and 6, a water content of between 40% and 65% by weight and a final density preferably greater than 1 ,300 kg/m 3 .
• liquid mixture M in order to increase the wettability and the gelifying property of the liquid mixture M, up to 10% by weight of glycols and/or up to 10% by weight of silanes and/or up to 10% by weight of saccharides are introduced.
• the mixture M is obtained by mixing colloidal silica dispersed in water with an aqueous solution of liquid alkali metal polysilicate.
• the aqueous solution of liquid alkali silicate and the solution of colloidal silica used for preparing the mixture M are easily found on the market.
• solutions of sodium and/or potassium silicate in water having concentrations of between 25% and 50% by weight and SiO 2 /Me 2 O ratios of between 1.5 and 4, are available on the market.
• the colloidal silica consists of sub-microscopic particles - having a diameter in the region of 10 nm - of amorphous silica dispersed in water. Dispersions with a variable silica content of between 15% and 50% by weight, typically used to form ceramic bonds in fibres or refractory materials, are commercially available.
• Table 1 shows some illustrative, non-limiting examples of compositions of alkali metal polysilicate solutions (of sodium, potassium, lithium or a mixture thereof) and colloidal silica.
• Table 2 shows some illustrative, non-exhaustive examples of preferred formulations for the formation of the mixture M.
• the mixture M is introduced in liquid form into the cavity C, which it easily fills even in the case of very complex or elaborate cross-sections. Moreover, it perfectly encapsulates any reinforcing elements 2 arranged inside the cavity.
• said reinforcing elements 2 are arranged in the cavity C before introduction of the liquid mixture M.
• the mixture M passes from the solution form to the gel form within a few dozen hours and without losing water, encapsulating in the gel all the water present.
• the passage from the liquid form to the gel form is favoured by high molar ratios, SiO 2 /Me 2 O, of over 3.5.
• a friable solid end product is obtained by means of the simple drying of the liquid mixture to a final water content of below 30% by weight.
• the solid gel form retains a significant plasticity over time allowing a seal having a plastic sheath G to adapt itself to the profiles to which it is joined. Moreover, being a solid, the intumescent mixture M does not leak even in the event of accidental local breakage of the sheath.
• the intumescent properties desired for the specific application are obtained by varying the quantity of residual water in the mixture M.
• the sheath G may be easily deformed.
• the intumescent seal 1 obtained is plastic and is able to adapt its shape to the profile of the cross-section with which it must be associated.
• the sheath G is made of thermoplastic polymer material, elastomer polymer material, thin metal - for example aluminium - sheets, or a combination thereof.
• the sheath G made of polymeric material, is rigid and has a cross- section of predetermined form.
• the polymer material may be of the thermoplastic or elastomer type or a combination thereof.
• the sheath G made either of easily deformable material or rigid material, contains a reinforcing element 3, which is at least partially embedded inside it.
• the reinforcing elements 2 and 3 are formed by a mesh or lattice of composite material having a high mechanical strength.
• Such composite material may be formed, for example, by glass fibres or carbon fibres.
• said mesh may also be obtained with a lattice of metallic material, and in particular iron, in which the filaments which form the meshes are less than a millimetre thick.
• the meshes of the lattice may have a width L of between 1 and 5 mm.
• the sheath G is folded in such a way as to form a structure having an almost toroidal cross-section with an opening 4.
• said form may be used for protecting long elements, such as cables, pipes or the like, from fire.
• the sheath G is obtained by means of drawing.
• a traditional auger or endless screw forces a mixture comprising polymeric material, expanding graphite and one or more flame-retardant substances, of an organic and/or inorganic nature, to pass through an extruding head which is generally heated to between 130° and 170°.
• the abovementioned mixture therefore takes on the form of a shaped body having a thickness, form and size suitably designed for the specific use.
• Said plant comprises retaining means 11 intended to support the external sheath G in a preferably vertical position so as to facilitate the filling of the containing chamber C, a container 12 which is intended to receive an aqueous solution of alkali metal polysilicate and colloidal silica dispersed in water and with which heating means 13 are operatively associated so as to increase the temperature of the solution contained therein, and stirring means 14 for mixing the abovementioned components inside it, resulting in the formation of an intumescent liquid mixture M.
• the plant also comprises circulating means 15 for transferring the intumescent liquid mixture M from the container 12 to the chamber C.
• the plant 10 is provided with degassing means 16 for performing the extraction, in the vapour phase, of at least a part of the water and the gases dissolved inside the intumescent liquid mixture M.
• degassing means 16 are advantageously formed by a duct 17, which connects the top part of the container 12 to the degassing means 16, a valve 18, which regulates the reduced pressure in the container 12 and is located on the duct 17, and suction means 19, which are associated with the duct 17 so as to subject the container 12 to the desired negative pressure (degree of vacuum).
• the quantity of water removed in this way is governed by the desired intumescent properties.
• the plant 10 described hitherto from a mainly structural point of view operates in the manner described hereinbelow.
• the sheath G is arranged between the retaining means 11 which have the function of keeping it vertical.
• the container 12 is then filled to the desired level with the alkali metal polysilicate solution and the aqueous dispersion of colloidal silica, which are then mixed together by means of the stirring means 14.
• the mixture M may be brought to the required temperature at the same time by means of the heating means 13.
• the degassing means 16 perform extraction, by means of the suction means 19, of the gases contained in the liquid and part of the water, in the vapour phase, through the second duct 17.
• the opening of at least one valve 20 arranged on the duct 15 is actuated.
• the mixture M is conveyed by means of the circulating means 15 into the containing chambers C.
• the present invention also comprises a method for the manufacture of heat- resistant seals, which may advantageously be achieved by means of the plant described above, to which reference will be made in the following description by way of example.
• the method according to the invention comprises the following operative steps: a step involving the provision of an internally hollow sheath so as to define the corresponding containing chamber C; a step involving mixing, in the chamber 12, the aqueous solution of alkali metal polysilicate with the colloidal silica dispersed in water, preferably with a molar ratio, SiO 2 /Me 2 O, of between 3 and 6, resulting in the formation of the intumescent liquid mixture M preferably having a density greater than 1 ,300 kg/m 3 ; a step involving degassing of the mixture M; a step involving filling of the containing chambers C with the mixture M; a step involving hardening of the mixture M inside the chambers C.
• a step involving heating of the intumescent liquid mixture M by means of the heating means 13 may also be envisaged, so as to assist the degassing and increase the speed of polymerization.
• the gases present in the mixture M which were introduced or dissolved in the preceding treatments or were present in the starting solutions as bought from the supplier, and a quantity of water are extracted by means of the degassing step so as to obtain a mixture M with the intumescent properties desired for the specific application for which it is intended.
• the degassing takes place by subjecting the intumescent liquid mixture M to a reduced pressure, preferably in the range of 20 to 500 millibars.
• the seal 1 may be advantageously mounted between a movable leaf and a fixed frame of a fixture or arranged around the edge of a fixed frame so as to receive the leaf of a door.
• seal 1 may also be used on fixtures of any other type and may also be used between several fixed panels for dividing spaces inside rooms.
• adhesion means which are formed for example by means of a layer of adhesive material and allow the seal to be installed easily, may be provided on a flat side of the seal 1.
• seal shown in Figs. 6 and 7 may be wrapped around cables and/or pipes in ducts formed in walls and/or panels.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Architecture (AREA)
• Organic Chemistry (AREA)
• Civil Engineering (AREA)
• Structural Engineering (AREA)
• Emergency Management (AREA)
• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Health & Medical Sciences (AREA)
• Inorganic Chemistry (AREA)
• Business, Economics & Management (AREA)
• Public Health (AREA)
• Fireproofing Substances (AREA)
• Sealing Material Composition (AREA)

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Publications (1)

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Cited By (10)

Citations (15)

• 2002
  • 2002-01-31 IT ITTN20020003 patent/ITTN20020003A1/it unknown
• 2003
  • 2003-01-31 WO PCT/IB2003/000323 patent/WO2003064801A1/en not_active Ceased
  • 2003-01-31 EP EP03734805A patent/EP1483473A1/en not_active Withdrawn

Patent Citations (15)

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