GB2357111A

GB2357111A - Polyurethane twin-walled fireproof structure

Info

Publication number: GB2357111A
Application number: GB9929215A
Authority: GB
Inventors: Derek Alfred Ward
Original assignee: Environmental Seals Ltd
Current assignee: Environmental Seals Ltd
Priority date: 1999-12-10
Filing date: 1999-12-10
Publication date: 2001-06-13
Anticipated expiration: 2019-12-10
Also published as: GB2357111B; GB9929215D0

Abstract

A method of producing a twin-walled structure, e.g. a fire door or partition wall, which comprises the steps of constructing an open-topped frame 1 comprising a base 2 bordered by upstanding sides 3 which respectively define one wall and side edges in the final structure, filling the frame 1 with a solution of polyurethane foam comprising a mix of isocyanate, particulate exfoliating graphite and/or sodium silicate and resin to a level at or just below the upper surfaces of the upstanding sides 3, applying to the surface of the fluid mix a releasing agent or member, e.g. paper, closing the open top of the frame 1, by means of a closure member and securing the closure member in place, allowing the mix to cure to produce a rigid polyurethane foam, removing the closure member and securing to the side edges and/or the solid foam a cover/sheet which defines in the final product the other wall of the structure. Blocks of wood or other suitable material 4 may be placed within the frame to coincide with fittings such as locking mechanisms, handles, etc.

Description

2357111 1 FIREPROOFED STRUCTURES This invention relates to fireproofed

structures and to methods of producing such structures.

Twin-walled fireproofed doors or panels are known in which the door or panel interior is filled with fire retardant material such as rockwool. The presence of such material is beneficial in the event of fire occurring but does lead to significant and sometimes unacceptable increases in weight of the respective door or panel. Additionally, the degree of fireproofing achieved is not as good as it could be because the material employed and of the presence of voids between the material and the panel or door walls.

The present invention sets out to provide an improved method of producing a fireproofed structure such as a door or panel which does not suffer from, or at least alleviates, many of the disadvantages present in existing fireproofed structures. The invention also provides a method of producing such structures.

In accordance with the present invention in one aspect there is provided a method of producing a twin-walled fireproofed structure which comprises the steps of constructing an open-topped frame comprising a base bordered by upstanding sides which respectively define one wall and side edges in the final structure, filling the space frame with a solution of polyurethane foam comprising a mix of isocyanate, particulate exfoliating graphite andlor sodium silicate and resin to a level at or just below the upper surfaces of the upstanding sides, applying to the surface of the fluid mix a releasing agent or member, closing the open top of the frame by means of a closure member and securing the closure member in place, allowing the mix to cure to produce a rigid polyurethane foam, removing the closure member and securing to the side edges andlor the solid foam a cover/sheet which defines in the final product the other wall of the structure.

The content of exfoliating graphite andlor sodium silicate may be between 10 and 75 % 0 by weight of the solution. Preferably, the content is between 10 and 25 % by weight. The ratio of isocyanate to polyol resin is typically 60:40, preferably 52:48.

2 The releasing member may comprise a sheet of paper or like material.

The invention will now be described by way of example, with reference to the accompanying diagrammatic drawing in which the sole Figure is a perspective view of a fireproofed twin-walled panelled door in accordance with the invention during construction.

A frame 1 for the door under construction is illustrated in the drawing. The frame comprises a base 2 bordered by upstanding sides 3. When constructed the base 2 defines one wall of the door and the sides 3 define the edge strips of the door. The base 2 may be produced from plywood, wood, card, metal or any other suitable material. The sides J3) may be produced from the same or similar materials.

Blocks of wood or other suitable material 4 are positioned on the base 2 to coincide with positions of required door fittings such as lock mechanisms, letter- boxes and the like.

The height of each block 4 is equal to the height of the sides 3.

As will be seen from the drawings, the base 2 and sides 3 effectively define an open- topped mould.

A polyurethane foam solution comprising a mix of isocyanate, polyol resin and powdered or particulate exfoliating graphite and/or sodium silicate is produced. The exfoliating graphite and/or sodium silicate is firstly mixed with the polyol resin solution, the mix then being added to the isocyanate solution. The quantity of exfoliating graphite and/or sodium silicate can be anything from 10 to 75 % by volume, and the ratio of isocyanate to polyol resin is typically 60:40, preferably 53:47 or 52:48. Following thorough mixing, the mixed solution poured into the frame 1 and around the sides of the blocks 4 until its level reaches the height of the sides J. Because foaming occurs a short time after mixing, pouring has to be completed as speedily as possible. A releasing agent such as a sheet of paper or like material is then applied to the exposed surface of the liquid mix and a closure member placed over the frame 1 and clamped firmly thereto. The closure member acts to contain the foam as it expands.

The filled structure is then put to one side for a sufficient period of time to allow it to dry and cure completely. Drying typically takes from two to four hours. Heating may be employed to accelerate drying. For complete curing a period of fourteen days may be necessary. Once cured the closure member is removed and the blocks replaced with the appropriate fittings. A suitable sheet of plywood, wood, card, metal or like material is then secured to the exposed surface of the frame by, for example, glueing.

Thus, expanded polyurethane foam completely fills the door interior and the exfoliating graphite andlor sodium silicate provides effective fire-proofing for the door.

Doors in accordance with the invention have been subjected to fire testing and have been found to provide adequate resistance for a period in excess of 90 minutes.

Whereas the invention has been described with reference to a fire door, it has application to a wide variety of twin-walled products. Such products include partitions, wall panels for items such as deep freezes, walls for temporary buildings, caravans, boats and the like.

It will be appreciated that the foregoing is merely exemplary of fireproofed structures in accordance with the invention and that various modifications can readily be made thereto without departing from the true scope of the invention set out above.

4

Claims

1. A method of producing a twin-walled fireproofed structure which comprises the steps of constructing an open-topped frame comprising a base bordered by upstanding sides which respectively define one wall and side edges in the final structure, filling the space frame with a solution of polyurethane foam comprising a mix of isocyanate, particulate exfoliating graphite and/or sodium silicate and resin to a level at or just below the upper surfaces of the upstanding sides, applying to the surface of the fluid mix a releasing agent or member, closing the open top of the frame by means of a closure member and securing the closure member in place, allowing the mix to cure to produce a rigid polyurethane foam, removing the closure member and securing to the side edges and/or the solid foam a cover/sheet which defines in the final product the other wall of the structure.

2. A method as claim in claim 1 wherein the content of exfoliating graphite andlor sodium silicate is between 10 and 75 % by weight of the solution.

3. A method as claimed in claim 2 wherein the content is between 10 and 25 % by weight.

4. A method as claimed in any one of the preceding claims wherein the ratio of isocyanate to polyol resin is 60:40.

5. A method as claimed in claim 4 wherein the ratio is 52:48.

6. A method as claimed in any one of the preceding claims wherein the releasing member is a sheet of paper or like material.

7. A twin-walled fireproof structure produced by a method as claimed in any one of claims 1 to 6.

8. A twin-walled fireproof structures substantially as herein described and as illustrated in the accompanying drawings.