EP0353540B2 - Fireproof doors insert with silica sol - Google Patents

Abstract

A fire-resisting wall element (1) reducing heat transition and with at least two insulating layers (2, 2a) made from bound mineral wool contains a layer (3) arranged between the insulating layers (2, 2a) which is produced from a mixture of a dehydrating hydroxide and an inorganic binder such as water glass or silica sol. The layer (3) increases the fire resistance of the wall element (1) which is therefore particularly suited as an insert for a fire-check door. <IMAGE>

Description

The invention relates to a fire-resistant, heat transfer reducing wall element, in particular as an insert for a fire-retardant door, according to the preamble of claim 1 and a method for its production.

In order to achieve a high fire resistance class for wall-like components, efforts are being made to combine thermal insulation layers with fire protection zones, the heat absorption capacity of which is significantly increased by the fact that endothermic chemical reactions or phase transformations take place when the temperature rises in the event of a fire. As is known, the fire resistance is determined by the duration at which a certain temperature rise on one side of the wall element, the other side of the wall element below a certain limit temperature, for. B. 180 ° C remains. The service life of the wall element until this limit temperature is reached on the cold side in minutes gives the fire resistance class, whereby according to DIN 4102, Part 5 z. B. the classification in fire resistance class F 30 means a 30-minute service life, F 90 a 90-minute service life etc. It is obvious that thermal insulation measures alone can only achieve a limited delay in the rise in temperature on the cold side, and this requires relatively large wall thicknesses. In addition, thermal insulation materials with a correspondingly high thermal resistance on the one hand and sufficient temperature resistance on the other hand are not available, with the exception of asbestos, which should not be used due to its health-threatening effects. Mineral wool, such as rock wool, sinters together from the hot side under the high fire temperatures and thus loses its effectiveness as a thermal insulation material relatively quickly on the hot side, so that relatively large wall thicknesses are required; Furthermore, mineral wool has a relatively low heat capacity and can therefore only delay the temperature rise on the cold side by its own heat absorption with small wall thicknesses.

Gypsum in particular is in practical use as a material for a layer that can delay the rise in temperature on the cold side due to the storage of latent heat as a result of phase change. The relatively high enthalpy is used when the crystal water is split off, which occurs from approx. 50 ° C. However, gypsum can only be handled as a layer with the dimensions required in practice in the form of so-called gypsum plasterboard, with a layer of gypsum being laminated on both sides with cardboard. The cardboard lining naturally increases the fire load and promotes the formation of flammable smoldering and decomposition gases.

There has therefore been no lack of attempts to produce such latent heat-absorbing fire protection zones from other substances which do not require laminations from organic substances or the like.

For this purpose, DE-OS 30 23 632 sodium metasilicate has become known, a substance that melts at around 48 ° C. while absorbing heat in its own crystal water and is stable in the molten state. Here, however, there is the problem that the melt with a relatively low viscosity is formed even at the lowest temperatures and, of course, tends to accumulate in the lower region of the available space. As a result, the hot upper area is completely exposed from the material of the layered fire protection zone, so that the temperature on the cold side rises practically abruptly there. According to the teaching of DE-OS 30 23 632, the sodium metasilicate is to be embedded in an open-pore support structure made of a wettable material, for example granulated mineral wool, to avoid draining away too quickly. According to a similar teaching of DE-OS 30 22 945, a substance is also to be introduced which binds the melt and forms a doughy or solid mass with it. It has been shown that such measures can delay the outflow of the melt. Another question is the low melting point of sodium metasilicate of approx. 50 ° C, which can also be achieved without fire under unfavorable influences, so that in an unfavorable case, melt can form and accumulate in the floor area without fire, which is, however, in the In the event of fire, the fire resistance of the wall element is generally not greatly reduced.

From DE-OS 35 10 935 a generic fire resistant, heat transfer reducing wall element according to the preamble of claim 1 is known. In the known wall element, the two insulation layers made of bound mineral wool are combined with at least one fire protection zone made of a granulate made of alkali or alkaline earth carbonate, the granulate being coated with an inorganic binder, e.g. B. magnesia binder. This known wall element offers sufficient resistance to a fire; however, since the material of the fire protection zone consists of alkali or alkaline earth carbonate in the form of granules, the fire protection zone is relatively wide, which leads to a relatively large structural thickness of the wall element. In addition, the known wall element is very heavy and prone to breakage.

A method for producing the wall element is also known from this document.

Another fire resistant wall element having the features of the preamble of claim 1 is known from GB-A-1 558 073. A layer of kaolin is provided as the inorganic material.

In contrast, the invention has for its object to provide a wall element of the type specified in the preamble of claim 1 and a method for its production, which in combination with mineral fiber insulation layers a high fire resistance class such as F 90 according to DIN 4102, part 5 in comparison with the stand the technology of reduced thickness and weight can easily achieve.

This object is achieved in terms of device technology by the characterizing features of claim 1 and in terms of process technology by the features of claim 14.

Substances are used as hydroxides or binders to ensure that no flammable and / or toxic gases are generated in the event of a fire. As water-releasing hydroxides, aluminum hydroxide Al (OH) ₃ or z. B. Magnesium hydroxide Mg (OH) ₂ , calcium hydroxide Ca (OH) ₂ , iron hydroxide Fe (OH) ₃ or FeO (OH) can be used, which with elimination of water in the corresponding oxides Al ₂ O ₃ , MgO, CaO, Fe ₂ O ₃ etc. are transferred. The conversion of the hydroxides into the corresponding oxides is an endothermic reaction, whereby heat is absorbed. Furthermore, water is released in a heat-consuming endothermic reaction, which escapes in the form of water vapor.

The binder has the function of binding the water-releasing hydroxide on at least one insulation layer in the form of a layer.

Außerdem steht Aluminiumhydroxid in einer Vielzahl von unterschiedlichen Präparationen, z. B. als Martinal (eingetragenes Warenzeichen des Martinswerkes, Bergheim) auf dem Markt zu Verfügung.Aluminum hydroxide Al (OH) ₃ (hydrargillite) changes to AIO (OH) (boehmite) when heated to approx. 150 ° C, which changes to gamma-aluminum oxide at approx. 400 ° C with elimination of water: $${\text{2 Al (OH)}}_{\text{3rd}}{\text{---- → 2 AlO (OH) ---- → Al}}_{\text{2nd}}{\text{O}}_{\text{3rd}}$$

In addition, aluminum hydroxide is available in a variety of different preparations, e.g. B. available as a martinal (registered trademark of the Martinswerk, Bergheim) on the market.

The measure of using the water-releasing hydroxide in different fractions with at least two particle size ranges leads to a higher packing density of the hydroxide. On the one hand, increasing the packing density has the advantage that more mass with endothermic and water-releasing properties can be introduced into the layer and, on the other hand, that the proportion of the more expensive binder can be reduced if necessary.

Of course, several fractions which are coordinated with respect to their grain size can also be used under certain circumstances, in particular to further save on binders, and under certain circumstances also different water-releasing hydroxides.

Furthermore, the increase in the packing density leads to a lower shrinkage of the layer during drying, as a result of which cracking can be largely suppressed.

The fact that the average grain size of the finest fraction is less than 2 microns ensures that this fraction fits well into the packing gaps formed by the spherical packing of the coarsest fraction with an average grain size of less than 100 microns and in particular lower 30 microns and thereby a tightly packed Compound of the dehydrating hydroxide, e.g. B. the aluminum hydroxide is formed.

Silica sol is a colloidal solution of amorphous silicon dioxide in water, to which small quantities of alkali are added to stabilize it in technical qualities. Commercial silica sols which occur as anionic or as cationic silica sols contain, for example, 15 to 45% by weight of solids, calculated as SiO ₂ . An anionic silica sol with a solids content of 30 to 45% by weight, in particular 40% by weight, is preferably added to the layer between the insulating layers of bound mineral wool of the wall element according to the invention as silica sol. In the mixture used according to the invention, silica sol serves as a binder and also splits off water upon transition into the crosslinked gel state and upon aging and during heating, with the formation of silicon dioxide according to the following equation: $${\text{Si (OH)}}_{\text{4th}}{\text{---- → SiO (OH)}}_{\text{2nd}}{\text{---- → SiO}}_{\text{2nd}}\text{.}$$

Aluminum hydroxide in the form of the commercial article Martinal is inert in the pH range between 3.5 and 10.5 and is insoluble in acids and alkalis. Therefore the mixture of Al (OH) ₃ (pH about 9.1) and silica sol (pH about 9 to 10) is stable.

Instead of silica sol, however, a water glass, for example potassium or sodium water glass in aqueous solution, can be used as the constituent of the mixture. Such solutions are strongly basic so that they slowly attack aluminum hydroxide. If this reaction with water glass has a disruptive effect, Mg (OH) ₂ , Ca (OH) ₂ , Fe (OH) ₃ or FeO (OH) or another hydroxide instead of aluminum hydroxide or a mixture of such hydroxides together with water glass can be used as the water-releasing hydroxide will.

However, any water-releasing hydroxide, for example Mg (OH) ₂ , Ca (OH) ₂ , Fe (OH) ₃ , FeO (OH) or a mixture of such hydroxides can be used together with silica sol.

To produce the wall element, a mass is made from a suitable water-releasing agent Hydroxide, e.g. B. aluminum hydroxide, and a silica sol processed into a plastic mass which is applied to one side of an insulation layer in a uniform layer.

The silica sol solidifies in the layer over a period of 2 to 8 hours. It can e.g. B. can be significantly shortened by heating or microwave drying. The water from the damp mixture of hydroxide and a water glass or silica sol is distributed to a small extent in the underlying insulation layer and can evaporate over time. However, the strength of the layer is not dependent on complete removal of the water, since it is primarily due to the transition of the water glass or silica sol to the crosslinked gel state.

However, a second layer of insulation can also be placed on top of the still wet layer and evenly bonded to the layer of plastic mass by applying slight pressure. By transitioning the silica sol into the cross-linked gel state, the two insulation layers are irreversibly connected or glued to one another in this procedure.

The binder is an organic substance, such as a polysaccharide, a polysaccharide derivative, in particular a polysaccharide ether, preferably a cellulose ether, such as. B. Tylose (registered trademark) or adding a synthetic resin has the advantage that drastic savings in binder can be achieved by this measure if necessary. This is due to the fact that the organic additive, for example tylose, even if it is used in fire-irrelevant concentrations of far below 1% by weight, based on the mixture of hydroxide and binder, still has such a bondability or adhesive strength of the hydroxide / binder Mixture has the effect that the usual binder concentration can be reduced by a factor of approx. 2 to 5. This results in an economical saving of binders, especially the relatively expensive silica brine.

70 to 95% by weight of aluminum hydroxide and 30 to 5% by weight of silica sol, calculated as SiO ₂ , in particular 80 to 90% by weight of aluminum hydroxide and 20 to 10% by weight of silica sol, for example 85% by weight, are preferably used. Aluminum hydroxide and 15 wt .-% silica sol. It is also possible to use clay or alumina or a clay mineral in the form of a powder or an aqueous slurry instead of a part of the aluminum hydroxide or in addition to aluminum hydroxide.

The wall element produced in this way has sufficient fire resistance for normal applications. If there is an increased requirement for fire resistance, one or more insulation layers can be stacked in the same way with the wall element produced in this way.

To increase the fire resistance values, the thickest possible insulation layers made from bound mineral wool can be used. However, the thickness of the insulation layers is limited by the prescribed maximum thickness of fire protection doors and by the high weight of fire protection doors with very thick insulation layers. In practice, panels with a thickness of 20 to 40 mm, in particular 30 mm and a bulk density of 140 to 280 kg / m ² , in particular 200 kg / m ^2, have proven to be good insulation layers. The layer of inorganic material is applied in a thickness of 2 to 5 mm, in particular 3 mm, so that the layer 3 has a basis weight of 5 to 10 kg / m ² , in particular 7 to 8 kg / m ² . With such a wall element 1, which can be constructed symmetrically if required, excellent fire resistance values can be achieved. The reason for this is probably that in this case the outer insulation layer made of mineral wool facing the respective fire initially insulates the layer of inorganic material, which also serves as a fire protection zone, and protects it from direct flame access, so that the latter is only later exposed to the full flame effect . In this case, the second insulation layer made of mineral wool remains, which is arranged on the cold side in order to effect the required insulation on the cold side. This insulation layer is protected by the layer acting as a fire protection zone and can therefore fully develop its insulation effect over a long period of time.

The fact that the layer has a nonwoven, in particular a nonwoven made of glass fibers, the cracking in the layer of water-releasing hydroxide and binder during the drying process and in particular during rapid drying, for. B. reduced or prevented under 4 min at 600 ° C. The fleece is integrated into the solidifying mass so that a heterogeneous layer is formed which contains water-releasing hydroxide, e.g. B. aluminum hydroxide, inorganic binder, e.g. B. contains silica sol and the fleece.

Another advantage of this measure is that the layer has a reinforcement due to the fleece lying on it, which improves handling during production.

Using rock wool as mineral wool has the advantage that it is very temperature-resistant on the one hand and, on the other hand, inexpensive in the required packaging, e.g. B. is to be produced as a plate.

Further details, features and advantages of the present invention result from the following description of an embodiment based on the drawing.

The figure shows a view of the wall element according to the invention.

The wall element 1 consists of two insulation layers 2, 2a made of mineral wool, between which a layer 3, made of a mixture of a water-releasing hydroxide and a silica sol, is arranged. Layer 3 serves as a fire protection layer since, in the event of a fire, it converts to aluminum oxide or silicon dioxide when heated and not only releases water vapor but also a large one during this endothermic conversion

Amount of energy consumed. Furthermore, the layer 3 forms a tight protective shield for the insulation layer 2 or 2a, which faces away from the fire. While the insulation layer facing the fire sinters together relatively quickly under the action of heat, layer 3 delays the sintering together of the insulation layer 2a or 2 facing away from the fire, as a result of which a rapid rise in temperature on the cold side can be avoided.

The wall element according to the invention serves in particular as an insert for a fire-retardant door. To produce such a door, the wall element 1 can be prefabricated on the one hand in the form of a double-layer plate sandwich and inserted between the sheet steel shells of a fire protection door. On the other hand, it is possible to insert an insulation layer in a sheet steel shell of the fire protection door, to apply the layer of the mixture of a water-releasing hydroxide and a silica sol to the insulation layer and then to fit the second insulation layer onto the layer in the steel sheet shell for the fire protection door, after which the two insulation layers be dried and cured.

Furthermore, it is also possible to prefabricate a composite panel connected via the layer 3, which then serves as an integral wall element 1 after the layer 3 has hardened.

According to a particularly preferred process, aluminum hydroxide is used as the water-releasing hydroxide in two fractions with different particle size ranges and silica sol as the inorganic binder. A mixture of 15.3% by weight aluminum hydroxide with a particle size range of 0.9 to 1.3 µm, 61 is preferred , 2 wt .-% aluminum hydroxide with a grain size range of 15 to 25 microns in solid form or in the form of a plastic aqueous slurry and 23.5 wt .-% silica sol. Instead of the silica sol, for example, dissolved water glass can also be used as the inorganic binder.

The use of a water-releasing hydroxide with two different particle size fractions results in the packing of the coarser fraction being filled by the particles of the smaller fraction in a denser packing of the endothermic converting hydroxide material. It also saves relatively expensive binders.

Due to the specified concentration ratio between hydroxide and binding agent, moisture penetration of the underlying or possibly applied insulation layer is largely avoided, since the water-releasing hydroxide is no longer sedimented and is therefore not washed into the fibers of the insulation layer.

The ingredients are mixed e.g. B. in a screw conveyor and brings the homogeneous mixture obtained onto one of the two insulation layers in a uniform layer. Then layer 3 is dried or, if necessary, the second insulation layer is applied to the still moist layer, pressed on and dried.

However, it is also advantageously possible to replace it with a small addition of an organic substance, such as tylose or starch, silica sol or water glass, which is irrelevant in terms of fire, for cost reasons, since such polysaccharides or polysaccharide derivatives are relatively high even in small amounts Have adhesive power and can thus partially replace the inorganic binder. This also applies to a large number of water-soluble synthetic resins.

If tylose is used as an organic additive, a mixture of 96.5% by weight aluminum hydroxide, 3.45% by weight silica sol and 0.05% by weight tylose, based on the dry mixture, is preferably used to produce the layer 3 used. This corresponds to a saving of far more than half of the usual amount of silica sol.

A further advantageous embodiment uses a glass fiber fleece to reinforce layer 3, which for example has a weight of 50 g / m ² . The fleece is on the layer 3 of aluminum hydroxide and binder z. B. applied by rolling, the fleece is connected to the layer 3 after drying and curing.

Furthermore, the use of a fleece applied to the hydroxide mixture reduces the formation of cracks, especially when the layer 3 is subjected to rapid drying, e.g. B. 3 minutes at 600 ° C.

The embodiment of the process according to the invention is particularly economical since the process can be carried out continuously or semi-continuously and the mixture can be produced in accordance with its consumption for the production of the layer.

Claims (19)

1. Fire resistant wall element reducing the passing through of heat in particular as insertion for a fire retarding door with at least two insulating layers (2, 2a) made of bound mineral wool between which a layer (3) made of a mixture of at least mainly inorganic material is disposed, characterised in that the layer (3) is made of a water separating hydroxide other than kaolin and a binding material, and
   whereby the water separating hydroxide is inserted in different fractions with at least two grain size fractions.
2. Wall element according to claim 1, characterised in that the water separating hydroxide is aluminum hydroxide.
3. Wall element according to claim 1 or 2, characterised in that the average grain size of the finest fraction is under 2µm.
4. Wall element according to claim 1 or 2, characterised in that the average grain size of the coarsest fraction is under 100 µm and preferably under 30µm.
5. Wall element according to one of the claims 1 to 4, characterised in that the binding material is silicic sol and/or water glass.
6. Wall element according to one of the claims 1 to 5, characterised in that the binding material contains an organic addition selected from the group consisting of: polysaccharides, polysaccharide derivatives in particular polysaccharide ethers preferably cellulose ethers and synthetic resins in fine technically irrelevant concentration.
7. Wall element according to one of the claims 1 to 6, characterised in that the layer is made of a mixture of 70 to 95 weight % aluminum hydroxide calculated at Al(OH)₃ and 30 to 5 weight % silicic sol calculated as SiO₂.
8. Wall element according to claim 7, characterised in that the mixture consists of about 85 parts by weight of aluminum hydroxide and about 15 parts by weight of silicic sol.
9. Wall element according to one of the claims 1 to 8, characterised in that the mixture contains, instead of a part of the water separating hydroxide or additionally to the water separating hydroxide, a clay or a clay mineral.
10. Wall element according to one of the claims 1 to 9, characterised in that the layer has a smaller thickness than each insulating layer.
11. Wall element according to claim 10, characterised in that the layer is 1 to 5mm in particular 3mm thick.
12. Wall element according to claim 10 or 11, characterised in that the layer has a fleece in particular a fleece of glass fibres.
13. Wall element according to claims 1 to 12, characterised in that the mineral wall is rock wool.
14. Process for the manufacture of a fire resistant wall element reducing the passing through of heat, according to claim 1, characterised in that in a continuous process a binding material is added to a water separating hydroxide other than kaolin in solid form or in aqueous slime

    whereby the hydroxide is inserted in different fractions with at least two grain size fractions for achieving a larger packing density;

    both constituents are mixed;

    the mixture obtained brought to one of the two insulating layers (2, 2a) in uniform layer (3) and the binding material can be consolidated by drying and the second insulating layer (2a) brought onto the consolidated layer (3) or the second insulating layer (2a) is brought on to the still moist layer (3) and the binding material can then be consolidated.
15. A process according to Claim 14, characterised in that the binder used is silica sol or dissolved water glass.
16. A process according to Claim 14 or 15, characterised in that an organic substance consisting of: polysaccharides, polysaccharide derivatives, especially polysaccharide ethers, preferably cellulose ethers and plastic resins, is added to the binder in a concentration which is irrelevant with regard to burning properties.
17. A process according to Claim 14, characterised in that a finest fraction with an average particle size of less than 2 µm is used.
18. A process according to Claim 14, characterised in that a coarsest fraction with an average particle size of less than 100 µm and preferably less than 30 µm is used.
19. A process according to Claims 14 to 18, characterised in that the layer is reinforced with a matting, in particular a matting of glass fibres.

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