DOOR ARRANGEMENT WITH FIRE PROTECTION FUNCTION

Abstract: In a method for the manufacturing of a door arrangement, particularly a door leaf, a door frame or a dressing of a door, with fire protecting properties, a first and a second door sheet, each door sheet having a first and a second surface (1), is used. A fire-protecting, substantially homogeneous silicate suspension (2), particularly comprising alkali metal silicate and filler, with hardener are applied to at least the first surface of the first door sheet. A filling material (3) is applied to said silicate suspension, whereafter the first and second door sheets are assembled to form a door leaf, so that the first surface of the respective door sheet is faced toward each other. Finally, the fire-protecting, substantially homogeneous silicate suspension is allowed to harden and give off part of its loosely bound water. The door leaf may also comprise absorber means (4). A door frame or a dressing of a door is manufactured in a corresponding way.

Description: DOOR ARRANGEMENT WITH FIRE PROTECTION FUNCTION TECHNICAL FIELD The present invention relates to a method in the manufacturing of a door arrangement, particularly a door leaf, a door frame or a dressing of a door, with fire protection function, and to the door arrangement itself. Furthermore it refers to the use of a silicate suspension as fire pro- tectection means in a door arrangement of said kind. PRIOR ART A general method in the manufacturing of a fire proof door comprises the cutting of panels made of gypsum or silicate into appropriate dimensions, whereby also openings are made for possible locks or the like. The panels are laid in place and may be fixed against the respective door sheet by an adhesive. An insulation material, e.g. mineral wool, may be applied to the gypsum panels for instance by adhesively securing, whereafter the door leaf is assembled. Each gypsum panel that covers a door sheet is about 6-12 mm thick and contains about 18-20 percent by weight tightly bound water. The German patent publication DE 36 03 705 (WOLFGANG ARHEILIGER) relates to a fire protection door with panels and spacers of asbestos-free silicate fibre (also called fibre calcium silicate) with a water content of not more than 10%. The spacers are arranged in pairs in such a way that spaces are formed between these and the panels. The spaces contain air or are filled with some other heat resistant and insulating material. The German patent publication DE 38 07 833 (PAUL SCH ITZ GMBH) relates to a sound-insulated steel door containing damping panels on the inside of the door sheets. The panels are of fibre silicate material and have also a fire 2 protecting effect. Mineral wool is applied in the door as a filling material. There also exist, as depicted in the European patent application EP 0 741 003 (GRUNZWEIG+HARTMANN AG) , fire protecting viscous silicate masses sandwiched between two glass-fibre textures, which masses are dried at a temperature of 130° Celsius. These fire protecting elements are prefabricated and are then appropriately cut to dimensions adapted for an application and mounted. The problems of these known fire protection doors and elements are that it is relatively time-consuming to cut the fire protecting panels and adhesively secure them and thereafter to secure the insulation. Besides, they are not flexible to the extent that if an extra strong fire protection is desired locally, this is difficult to achieve. The door leaves also become rela- tively heavy. Furthermore, the silicate masses need a relatively long hardening or drying time. The panels are intermediate stored in this respect at least a few days. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method in the manufacturing of a door arrangement, particularly a door leaf, a door frame or a dressing of a door, with fire protection function that is effective and flexible. Another object of the invention is to provide a fire protecting door arrangement of relatively low weight and to a low cost. These and other objects are accomplished according to one aspect of the invention by a method according to which a 3 first and a second door sheet, each door sheet having a first and a second surface, are provided. A fire protecting mainly homogeneous silicate suspension with hardener is applied to at least the first surface of the first door sheet. The silicate suspension ought to comprise a silicate of an alkali metal and a filler, preferably manufactured according to a method where the filler is treated with an acid in a slurry, whereafter this is mixed with an aqueous solution containing a alkali metal silicate. The method is further described in the European patent application EP 0 507 368 (THORS KEMISKE FABRIKKER A/S) . A filling complement material, such as for instance the insulation material mineral wool, is applied to said silicate suspension, whereafter the door leaf is assembled, i.e. the first and second door sheets are mounted with the first surface of the respective door sheet facing each other. Finally, the fire protecting mainly homogeneous silicate suspension is allowed to harden and give off part of its loosely bound water. The fire protecting mainly homogeneous silicate suspension is preferably applied in a relatively large amount, particularly at least 1-2 kg per square meter door sheet. In this respect it is possible to apply the silicate suspen- sion in a varying amount over the surface to locally vary the fire protecting capability of the door leaf. The silicate suspension may also be applied to the first surface of the second door sheet. Conventional glue may be applied to further increase the adhesion in the door leaf. A problem of such an inventive door leaf, particularly in environments with large temperature gradients, may be that the silicate suspension gives off so large amounts of water that the door leaf leaks out water. It is therefore preferable to locate an absorbent means in the door leaf for absorption of the water that is given off from the fire protecting mainly homogeneous silicate suspension. The absorbent means is drying during a very long period of 4 time. Alternatively, or as a complement, the door leaf may be held at a higher temperature during assembly. A preferable temperature is hereby about 50-70° Celsius. The temperature should be high enough to yield a fast evaporation but at the same time low enough to prevent the tightly bound water (that constitutes the real fire protection) to vanish. It is also possible to blow, particularly with compressed air, through the door leaf and hereby remove further water. According a second aspect of the invention the above described method is utilized in a corresponding way in the manufacturing of a door frame and a dressing of a door with fire protecting properties. The advantages of the present invention comprise a simpler and cheaper manufacturing process and flexibility in placement of the fire protecting material. Yet another advantage of the invention is that the mainly homogeneous silicate suspension is non-polluting and allows for a non-polluting manufacturing process. It serves also as a sound-absorbing material. Still another advantage is that the door leaf is lighter (about 10-20 kg lighter for a door with a 60 minutes classed fire protection) , which implies another, more advantageous, dimensioning of hinges and cheaper transports. The weight of the door leaf is certainly affected by the choice of thickness of the sheet metal and amount of applied silicate suspension. Further advantages of the invention will be apparent from the specification below. SHORT DESCRIPTION OF THE DRAWINGS The invention is described closer below with reference to Figures 1-3, which are shown only to illustrate the inven- 5 tion and shall therefore in no way limit the same. Figure 1 shows a fire protecting door leaf in two views according to the present invention. Figure 2 shows a cross-section of said inventive door leaf along the line A-A in Figure 1. Figure 3 shows part of said cross-section in larger scale. PREFERRED EMBODIMENTS In the following description, with purposes of explanation and not limitation, specific details are set forth such as particular applications, techniques etc to give clear understanding of the invention. It shall though be clear to the man skilled in the art that the invention may be performed in other ways. In Figure 1 an inventive door leaf is shown comprising door sheets 1 made of steel sheet. They may be bent along the sides so that they more easily may be assembled to the finished door leaf. A silicate mass or a silicate suspension 2 is mixed with a hardener (accelerator) and is applied to the door sheets 1 through an orifice in relatively large amount, particularly about 10 times more than with conventional gluing, which implies about 1-6 kg for a door leaf in a standard size (about 1-3 kg/m 2 ) . Applied amount is related to the fire protection desired and the other parameters of the door. The silicate suspension, which is also referred to as a silicate-based binder, and comprises alkali metal silicate and filler, is object to a separate patent application, see EP 0 507 368, which publication is hereby included as a reference. The binder is further described below in this description. The hardener or accelerator, that may contain about 30-60% esters, is applied preferably in small amounts, particularly about 2-5% of the amount 6 of silicate suspension. To achieve a satisfactory fire protection a two-component mass is probably necessary. Examples of products comprising such a silicate suspension and hardener are Thorsil 7104™ and Thorsil K67-P™ manu- factured by EKA CHEMICALS. The applying is performed in flowing form so that parts of or the complete surface is covered by a couple of millimeters thick layer of silicate suspension. This applying is very flexible and if a better fire protection is desired locally, a thicker layer of suspension is applied there. A filling material 3 is then applied, which preferably is constituted by an insulation material such as mineral wool, a spacer or the like, whereafter the door sheets 1 are mounted together to form a door leaf. In this respect the door sheets are screwed or welded together. They may alternatively be mounted on a frame of, for instance, bent or rolled steel sheet. The door sheets may also be integral with each other from the beginning, i.e. constitute part of solely one sheet. In this respect cutting out, mounting and gluing of the panels that are described in known art may be despensed with. Fire protection and adhesion may now be obtained at the same time by the same material. A fire proof door made of wood may be manufactured accord- ing to the invention in a corresponding way. The door sheets are manufactured in wood or in some laminate material and the filling material may be constituted preferably of fibreboard. A traditional water glass consists of about 35% of a mixture of Na 2 0 and Si0 2 , commonly in the relationship 1:3,4, and the rest is water. This implies that such a water glass may give off all its water at room tempera- 7 ture. In practice there remains a lesser part tightly bound water, about 5%, that vanishes first at higher temperatures. In the mainly homogeneous silicate suspension utilized in the present invention the portion tightly bound water is approximately 20-25% and the portion free water is of the same size. The rest is dry substance. Tightly bound water means water that vanishes at a higher temperature, parti- cularly at about 100-110°C, and loosely bound (or free) water means water that vanishes during the time at room temperature. The fact that the tightly bound water, which constitutes the main part of the fire protection, vanishes at a temperature of about 70-150 °C or around, is essential for its fire protecting capability. The silicate suspension may be manufactured according to the following. A filler is treated with an acid in a slurry, whereafter the slurry is mixed with an aqueous solution of an alkali metal silicate to a mainly homogeneous suspension. The acid is preferably an aqueous soluble organic acid. The filler, that ought to be relatively stable in an acid environment and mainly stable in an alkali metal silicate solution, may be constituted of particles of kaolin, feldspar, pearlite, titanium dioxide, aluminium trihydrate, muscovite, talc or the like with a preferable diameter less than about 100 μm. Preferably, the filler is applied in an amount corresponding to 4-80 percent by weight of the alkali metal silicate. The alkali metal silicate is a mixture of M 2 0, where M is sodium, potassium or a mixture thereof, and Si0 2 in a relationship of 1 to about 2-4. The suspension manufactured in this manner is constituted by a substantially stable mass that does not stratify. It is highly viscous (about 20000 centipois) and has a relatively good adhesion capability on certain kinds of sheet material, for instance zincified sheet material. 8 The silicate suspension described is not as sensitive to moisture as a traditional water glass and it does not give off as much water. The silicate suspension is not commonly applied to the upbent edges of the sheets, but it may so be done. Conventional adhesive may also be applied to further increase the adhesion capability. The fire protection agent may furthermore be applied in a door frame and a dressing of a door, see below. The loosely bound or free water vanishes commonly during a period of about two years in a mounted door leaf (much faster if the silicate suspension is lying exposed) . A further fire protection the two first years may hereby be achieved. However, this implies also problems because of the fact that such large amounts as 1.5-2 kg water vanish. Two solutions to this are proposed. The first solution comprises that an absorber means 4 is applied in a door leaf and this absorbs the amount of water given off from the silicate suspension, so that the door leaf does not leak. The absorber means, which preferably is applied in thin light layers, may absorb up to 100-200 times its own weight and dries over very long time. The other solution comprises removing of the water (as far as possible) during manufacturing of the door leaf. This is performed by holding the door leaf during mounting at a temperature of 50-70° Celsius, whereby partly the mass hardens faster, partly the free water evaporates. By blowing through the insulation by compressed air, large amounts of water may be removed. During experiments half of the water, i.e. 6 dl, has been blown away in about 15 in. The door leaf should, however, not be heated so the 9 first tightly bound water starts to vanish - the fire protection capability of the door leaf is thus reduced. Tests in both model scale and full scale have shown that a door leaf according to the present invention pass the so- called El-fire protection requirements with large margin as regards both temperature rise and integrity. It has also been shown that not more than 25% of the weight of the silicate suspension can vanish at normal room tempera- ture and humidity. Laboratory-aged test elements exhibit very good fire protection properties. In the present invention the term door leaf is considered to include also gates and shutters. The door leaf may be a square-edge door or a rabbeted door leaf. Furthermore, the invention is applicable on other parts comprised in a door arrangement. For instance the silicate mass may be applied to a door frame, to its door frame side and/or to its door frame head. The frame may be a single or a double chamfer frame or a special door frame. Furthermore, the silicate suspension may be applied to a dressing of a door. The present invention, as hereby described, solves the problems associated with known art by utilizing the prin- ciple of using a liquid material, particularly a silicate suspension, for direct application to door sheets, to door frames and to door dressings, for fire protection function or fire protection function and adhesion function. It is obviously not limited to the embodiments described above and shown on the drawings, but may be modified within a scope of the appended claims.

Claims: 10 CLAIMS 1. Method in the manufacturing of a door leaf with fire protection function, c h a r a c t e r i z e d b y the steps of: - providing a first and a second door sheet (1) , each door sheet having a first and a second surface; - applying adhesive, fire-protecting, substantially homogeneous silicate suspension (2) with hardener to at least the first surface of the first door sheet; - applying a filling material (3) to said silicate suspension; - assembling then the first and second door sheets (1) to a door leaf so that the first surface of the respective door sheet is faced toward each other, and - allowing the fire-protecting, substantially homogeneous silicate suspension (2) finally to harden and give off part of its loosely bound water. 2. Method as claimed in Claim 1, c h a r a c t e r i z e d y manufacturing the substantially homogeneous suspension (2) by treating a filler with an acid in a slurry, whereafter the slurry is mixed with an aqueous solution of an alkali metal silicate. 3. Method as claimed in Claim l or 2, c h a r a c t e r i z e d b y applying the fire-protecting, substan- tially homogeneous silicate suspension (2) also the first surface of the second door sheet. 4. Method as claimed in any of Claims 1-3, c h a r a c t e r i z e d b y applying the fire-protect- ing, substantially homogeneous silicate suspension (2) in such a way that parts of or the complete surface is covered by a layer of a thickness of a few millimeters. 11 5. Method as claimed in any of Claims 1-4 , c h a r a c t e r i z e d b y applying the fire-protecting, substantially homogeneous silicate suspension (2) locally in a varied amount, particularly in a thicker layer, to locally vary the fire-protecting capability of the door leaf, particularly increase the fire protection. 6. Method according to any of Claims 1-5, c h a r a c t e r i z e d b y also applying conventional adhesive to further increase the adhesion in the door leaf. 7. Method according to any of Claims 1-6 , c h a r a c t e r i z e d b y applying absorber means (4) in the door leaf for absorbing loosely bound water that is given off from the fire-protecting substantially homogeneous silicate suspension (2) . 8. Method according to any of Claims 1-7 , c h a r a c t e r i z e d b y holding the door leaf during assembly at a temperature of 50-70° Celsius for evaporating loosely bound water. 9. Method according to any of Claims 1-8 , c h a r a c t e r i z e d b y blowing, particularly by compressed air, through the door leaf. 10. Door leaf with fire protection function comprising a first and a second door sheet (1) , a silicate layer (2) and a filling material (3), c h a r a c t e r i z e d i n being manufactured according to the method as claimed in any of Claims 1-9. 11. Use of a substantially homogeneous silicate suspension (2) , manufactured according to a method in which a filler is treated with an acid in a slurry, whereafter said slurry is mixed with an aqueous solution of an alkali metal silicate, together with a hardener as fire- 12 protecting means in a door arrangement and as adhesive means for a filling material in the door arrangement. 12. Method in the manufacturing of a door frame or a dressing of a door with fire protection function, c h a r a c t e r i z e d b y applying an adhesive, fire-protecting, substantially homogeneous silicate suspension with hardener (2) to the door frame or the dressing of a door, applying a filling material (3) to said silicate suspension and allowing the adhesive, substantially homogeneous silicate suspension to harden and give off part of its loosely bound water. 13. Method according to Claim 12, c h a r a c t e - r i z e d b y manufacturing the substantially homogeneous suspension (2) by treating a filler with an acid in a slurry, whereafter the slurry is mixed with an aqueous solution of an alkali metal silicate. 14. Door frame or dressing of a door with fire protection function comprising a silicate layer (2) , c h a r a c t e r i z e d i n that the silicate layer is manufactured by the method according to Claim 12 or 13.

Inventors: JOHANSSON HENRIK, OLOFSSON INGEMAR, JOHANSSON, HENRIK, OLOFSSON, INGEMAR
Applicants: DALOC AB, JOHANSSON HENRIK, OLOFSSON INGEMAR, JOHANSSON, HENRIK, OLOFSSON, INGEMAR
Application year: 1999
Main classification: E06B5
IPC codes: E06B5