FLEXIBLE SEAL

Abstract: A flexible expandable seal comprises a preformed flexible cellular fire-retardant foam or sponge coated firstly with a primer solution including a sealant and secondly with a flowable coating of a fire-retardant material. The primer solution operates to close the open pores of the coated surface and provides a bond to which the fire-retardant coating can adhere.

Description: FLEXIBLE SEAL This invention relates to preformed flexible expandable seals of foam or sponge. Flexible expandable seals are used, for example, as movement joints between external and internal walls of buildings, between partitions and in roofing sections and concrete ceilings to provide inter alia fire-retardant properties. Flexible expandable seals are known which comprise a preformed flexible cellular foam or sponge which has been impregnated with fire-retardant material. When subjected to temperatures of the order of 300-400 °C such seals lose integrity thereby allowing flames to pass between the walls or other members between which the seal is positioned. Expandable seals are also known which comprise layers of sponge and intumescent sheets. The sponge content of these seals deteriorates at temperatures around 200°C while the sheets expand. Seal flexibility is therefore substantially lost. The present invention sets out to provide a flexible expandable fire-retardant seal which does not suffer from, or at least alleviates, many of the disadvantages to be found with existing seals. According to the present invention in one aspect, there is provided a flexible expandable seal which comprises a preformed flexible cellular fire-retardant foam or sponge at least one of whose surfaces is coated firstly with a primer solution including a sealant and secondly with a flowable coating of a fire-retardant material, the primer solution operating to close the open pores of the said at least one surface and to provide a bond to which the fire- retardant coating can adhere. All surfaces of the foam or sponge may be coated. The primer solution may comprise an aqueous solution of an acrylic copolymer which includes ammonium polyphosphate. The fire-retardant coating may comprise a chlorinated vinyl copolymer system which includes a quantity of ammonium polyphosphate , zinc borate and/or magnesium and/or calcium carbonates. The foam or sponge may comprise polyurethane or alternatively a silicone coated with a silane primer. The primer solution may be allowed to dry before the fire-retardant material is applied. One or both coatings may be applied by brushing, rolling or spraying. In another aspect, the invention provides a flexible expandable seal which comprises a pre-formed flexible cellular fire-retardant foam or sponge whose surfaces are coated sequentially with coatings of a primer solution including a sealant and a fire-retardant material. In one example, a block of polyurethane foam material impregnated with an aqueous solution of a fire-retardant material is coated on all of its surfaces with a solution of an acrylic copolymer system which includes ammonium polyphosphate. At temperatures in excess of 250 °C to 300 °C the ammonium polyphosphate forms phosphoric acid which reacts with the fire-retardant coating for the polyurethane block. This primer coating has a viscosity similar to that of water and acts to seal the open cells of the polyurethane foam. The primer coating therefore seals the exposed surfaces of the polyurethane block whilst retaining the flexibility characteristics of the block. The primer coating also provides a bond to which the subsequently applied fire retardant coating can adhere. The surfaces of the polyurethane block are then coated with one or more coatings of a chlorinated vinyl copolymer system which includes a quantity of ammonium polyphosphate, zinc borate and/or magnesium and/or calcium carbonates. The viscosity of this fire-retardant coating is more akin to an emulsion or paste. The coatings may be applied by means of a brush, roller or spray. The primer coating not only seals the open pores of the polyurethane block but also, as mentioned previously, provides a primed surface to which the fire-retardant coating can adhere. The coated block retains its flexibility and the bond between the respective coatings is sufficient to prevent cracking or other damage to the surface during handling of the block. In some instances it may be preferable to allow the primer coating to dry before the fire-retardant coating is applied It will be appreciated that the foregoing is merely exemplary of fire-retardant seals in accordance with the invention and that various modifications can readily be made thereto without departing from the true scope of the invention

Claims: CLAIMS 1. A flexible expandable seal which comprises a preformed flexible cellular fire-retardant foam or sponge at least one of whose surfaces is coated firstly with a primer solution including a sealant and secondly with a flowable coating of a fire-retardant material, the primer solution operating to close the open pores of the said at least one surface and to provide a bond to which the fire-retardant coating can adhere. 2. A seal as claimed in claim 1 wherein all surfaces of the foam or sponge are coated. 3. A seal as claimed in claim 1 or claim 2 wherein the primer solution comprises an aqueous solution of an acrylic copolymer which includes ammonium polyphosphate. 4. A seal as claimed in any one of the preceding claims wherein the fire-retardant coating comprises a chlorinated vinyl copolymer system which includes a quantity of ammonium polyphosphate, zinc borate and/or magnesium and/or calcium carbonates. 5. A seal as claimed in any one of the preceding claims wherein the foam or sponge comprises polyurethane. 6. A seal as claimed in any one of claims 1 to 4 wherein the foam or sponge comprises a silicone coated with a silane primer. 7. A flexible expandable seal which comprises a pre-formed flexible cellular fire- retardant foam or sponge whose surfaces are coated sequentially with coatings of a primer solution including a sealant and a fire-retardant material. 8. A flexible expandable seal substantially as herein described.

Inventors: WARD DEREK ALFRED, WARD, DEREK, ALFRED
Applicants: ENVIRONMENTAL SEALS LTD, WARD DEREK ALFRED, ENVIRONMENTAL SEALS LIMITED, WARD, DEREK, ALFRED
Application year: 2001
Main classification: E04B1
IPC codes: C09D5, E04B1