WO2003014211A1

WO2003014211A1 - Fire-retardant synthetic material and isolation material as well as a method for making synthetic material fire-retardant

Info

Publication number: WO2003014211A1
Application number: PCT/NL2002/000453
Authority: WO
Inventors: Albert Fleury
Original assignee: Applinovation B.V.
Priority date: 2001-08-07
Filing date: 2002-07-10
Publication date: 2003-02-20

Abstract

Into a synthetic material with fire-retardant properties is processed a silicate compound which forms foam at increased temperature. An insulating material is formed herefrom in a foamed, form-retaining state. This insulating material particularly comprises mutually cohesive cores (11) which are at least largely enclosed with a layer (12) which contains a silicate compound and which forms foam at increased temperature. In order to make a synthetic material fire-retardant an additive is added thereto comprising a silicate compound which forms foam at increased temperature.

Description

Fire-retardant synthetic material and isolation material as well as a method for making synthetic material fire-retardant

The present invention relates to a synthetic material with fire-retardant properties as well as to a fire-retardant insulating material in which such a synthetic material is applied. The present invention also relates to a method for making a synthetic material fire-retardant.

Synthetic materials are applied on a large scale in the construction of houses and other buildings. This relates not only to the building of new houses but also to renovation of existing buildings. In addition to numerous other applications, synthetic materials find wide application here as waterproof foils for the purpose of a desired moisture barrier, in foamed form as insulating material for thermal and acoustic insulating purposes, and as filler for holes and gaps.

The preference for synthetic materials in the above stated and other situations results from the high durability thereof in combination with a usually light weight, excellent heat insulation, easy workability and relatively low cost price. Synthetic materials also have an important drawback, however, in that they normally catch fire easily. This property is difficult to equate with diverse fire regulations usually imposed by government authorities on buildings, and in particular houses, from the viewpoint of fire prevention.

In order to obviate this latter drawback, a polyethylene foam is provided in European patent specification 375,738 with fire-retardant properties by glueing a metal plate thereon. The thus obtained laminate is intended as fire-retardant, insulating wall covering for tunnel tubes, wherein the fire-retardant properties are derived from the inert metal plate.

Although the covering of the known synthetic material with a metal plate provides per se a certain measure of fire-retardance, on the other hand it largely negates the above stated advantages of synthetic material. The metal covering will thus generally result in a greater weight, a higher cost price and a more difficult workability. International patent application WO 0136527 describes the addition of an organophosphate to a polyphenylene ether. According to the American patent USP 6,143,816 an aluminium oxide hydrate is added, while according to European patent application no. 1,024,167 a salt of a phosphinic acid is added together with a synthetic inorganic material. The above stated additives are however relatively expensive and/or fire-retardant to a relatively limited degree. Furthermore, such additions not infrequently result in toxic waste gases if exposed to high temperatures as in the case of fire.

The present invention has for its object, among others, to provide a synthetic material and insulating material of the type stated in the preamble, to which fire-retardant properties are given, while retaining at least in large measure the above described intrinsic advantages of synthetic materials and without essentially influencing the cost price thereof.

In order to achieve the intended object, a synthetic material according to the invention has the feature that a silicate compound is processed thereinto which forms foam at increased temperature. The invention is herein based on the insight that a synthetic material thus acquires intrinsic fire-resistant, at least fire-retardant properties without or at least hardly without relinquishing the normal properties of the synthetic material. The synthetic material thus retains its normal specific weight and insulating properties, although the addition thereto according to the invention of the silicate compound ensures that, in the case of fire, an inert foam will form therein which keeps the synthetic material from catching fire and thus prevents the fire from spreading.

The silicate compound can be added later by covering the synthetic material with one or more layers thereof or mixing it therewith, while in a preferred embodiment the synthetic material according to the invention is characterized in that the synthetic material comprises a polymer and that the silicate compound is added as additive at the latest during a polymerization thereof. By thus already adding the silicate compound before or during the polymerization, an optimal mixing and an optimal homogenous distribution of the compound in the material is obtained.

Particularly good results have been demonstrated in practice with a particular embodiment of the synthetic material according to the invention, characterized in that the silicate compound comprises an alkali metal silicate, in particular a sodium silicate, and more particularly in that the silicate compound comprises a sodium silicate from a group of Na₂SiO₃.5H₂O and Na₂SiO₃.9H₂O. Sodium silicate, in particular sodium metasilicate, is an inexpensive raw material which is used for instance as glue, in cleaning agents and in the metal industry. This raw material has the feature, when heated from a temperature of 110 to 130°C, of forming foam which remains stable up to a temperature of 1089°C, at which it melts. This foam, which first occurs on the outermost layers, forms an insulating protection for the underlying layers, whereby an object manufactured from the synthetic material retains its load- bearing capacity for longer in a fire. Very suitable sodium metasilicates are found to be Na₂SiO₃.5H₂O and Na₂SiO₃.9H₂O.

With a view to the fire resistance of the whole, a further particular embodiment of the synthetic material according to the invention has the feature that it is a thermoset. Thus starting from a thermoset achieves that the material remains form-retaining and will not collapse, even at increased temperature. The addition of the silicate compound according to the invention contributes toward the material not catching fire and retaining its shape.

Although the invention can be applied with many types and forms of synthetic material, particularly good results have been achieved in practice with a further particular embodiment according to the invention, characterized in that it comprises a polyester.

An important field of application for a synthetic material with fire-retardant properties according to the invention is as insulating material, particularly in the construction industry, irrespective of whether this is in the building of new houses or renovation and existing buildings. Insulating materials usual heretofore normally comprise blankets of mineral wool, such as rock wool and glass wool, or foamed polyurethane and polystyrene plates. The first mentioned insulating materials are fire-retardant to a certain degree but not very form-retaining and therefore less simple to process, and moreover have a relatively great density. Known foamed plates do not have these drawbacks but do catch fire exceptionally easily and without additional measures cannot therefore be highly recommended from a fire prevention viewpoint. The invention also provides a solution in this respect in that it also relates to a fire- retardant insulating material which comprises according to the invention a fire- retardant synthetic material as specified above in a foamed, form-retaining state.

In a particular embodiment a fire-retardant insulating material according to the invention has the feature that the synthetic material is at least substantially constructed as mutually cohesive cores which are at least largely enclosed with a layer which contains a silicate compound and which forms foam at increased temperature. The foam-forming layer with which the cores are thus enclosed will foam up in the case of fire and thus thermally insulate and passivate the core enclosed thereby. The foamed covering thus provides a barrier which prevents a further spread of the source of fire. The physical and mechanical properties of the insulating material are however not affected before this, or hardly so, by the presence of the fire-retardant layer or layers therein.

A fire-retardant insulating material according to the invention has the more particular feature that the form-retaining state comprises a plate of stacked layers of the synthetic material which are glued together with interposing of the silicate compound- containing layer. An insulating material can thus be provided with fire-retardant properties from the start, or be modified only afterward in this sense. In the latter case use is made for instance of a conventional insulating plate material which is divided laterally or transversely into strips and subsequently joined together again with interposing of the foam-forming layer. In a further particular embodiment the insulating material according to the invention has the feature that the silicate-containing compound is mixed at least almost homogeneously with the synthetic material. Such a homogenous distribution of the silicate compound in the material ensures uniform, isotropic fire-resistant properties thereof, whereby even the smallest core will not catch fire. In a further particular embodiment the insulating material is furthermore characterized in that the silicate compound is applied from a dry form by mixing grains or powder thereof with a basic synthetic material.

The invention also relates to a method for making a synthetic material fire-retardant, which is characterized according to the invention in that an additive containing a silicate compound which forms foam at increased temperature is added to the synthetic material. In the thus obtained synthetic material the additive is present in very finely upgraded form so that exceptional homogenous fire-retardant properties are obtained. The synthetic material is hereby eminently suitable for fire-retardant applications, for instance in the above described insulating material. Particularly good results have been achieved in this respect with a particular embodiment of the method according to the invention, characterized in that the additive comprises a sodium silicate, and characterized more particularly in that sodium metasilicate, and in particular a silicate from a group of Na₂SiO₃.5H₂O and

is added as additive.

In a further embodiment the method according to the invention has the feature that the additive is added to the synthetic material in solid form, in particular as powder or grains. The additive can herein be mixed with the synthetic material at the start, or be arranged only afterward by for instance glueing it, optionally under pressure, to grains of the synthetic material. A preferred embodiment of the method according to the invention has the feature however that the additive is added to a liquid component of the synthetic material, preferably before polymerizing the synthetic material. By thus making use of a liquid form of the synthetic material the additive can be mixed therewith very homogeneously, particularly if this takes place before the polymerization of the synthetic material takes place.

Particularly good results are achieved in this respect with a further embodiment of the method according to the invention which is characterized in that a polyester is applied as synthetic material, and more particularly in that the additive is mixed with a liquid phase of a two-component polyester. A very suitable application of the invention is found in this respect in polyester, wherein sodium metasilicate is mixed with a liquid phase of a two-component polyester.

In order to better demonstrate the insight and the features of the invention, several preferred embodiments will be given hereinbelow, by way of example and without any limitative character, of a method for making fire-retardant a synthetic material and an insulating material according to the invention, with an accompanying drawing. In the drawing: figure 1 shows a cross-section of a fire-retardant insulating material according to a first embodiment of the invention; and figure 2 shows a cross-section of a fire-retardant insulating material according to a second embodiment of the invention. The figures are otherwise purely schematic and not drawn to scale. For the sake of clarity some dimensions in particular are exaggerated to a greater or lesser extent.

Embodiment I: A per se flammable insulating material, such as foamed insulating plates formed from polyurethane or polystyrene, can be provided according to the invention with fire- retardant properties by including a foam-forming silicate compound therein as additive. For this purpose such a plate material is for instance assembled transversely or laterally from a number of sub-layers 10, see figure 1, which are glued together by means of a glue 1 1 containing the silicate compound and are preferably also covered on the outermost side. A silicate compound is herein applied which has the property of foaming up at increased temperature and therein forming a passivating and insulating protective layer. Particularly good results have been realized in this respect using a glue on the basis of sodium metasilicate, in particular Na₂SiO₃.5H₂O and Na₂SiO₃.9H₂O which, after being heated, display an exceptionally good adhesion to polyurethane and polystyrene foam. A fire-retardant insulating material is thus created with cores 11 of the original foamed synthetic material which are enclosed by a fire- retardant skin of the silicate compound.

Embodiment II: A thoroughly fire-retardant insulating material is obtained by making use of grains 21 of a foamed synthetic material, such as for instance polyurethane or polystyrene, and glueing these grains together at increased pressure to form a plate or other form- retaining state, making use of a glue 22 comprising a silicate compound as specified above. The thus obtained result is shown in figure 2. Here the glue containing a silicate compound, such as particularly sodium metasilicate, is thoroughly processed so that a fire-retardant effect emanates through the whole material thereof.

Embodiment III:

In order to make a polyester fire-retardant, powder or grains of a sodium metasilicate are mixed with monomeric, at least not fully polymerized ester. Suitable sodium metasilicates are Na₂SiO₃.5H₂O and Na₂SiO₃.9H₂O. The quantity of sodium metasilicate can lie between 30% by weight and 200% by weight, calculated according to the quantity of ester. In the ester component substances other than the fire-retardant sodium metasilicate can be added, such as glass fibres or other strengthening fibres. After adding hardener to the mixture, the ester polymerizes fully and a thermo-setting polyester synthetic material is formed.

In the case of fire, the polyester in the top layer which is exposed to the heat will in the first instance combust, and the sodium metasilicate lying close to this top layer will melt, but from a temperature of 110 to 130°C it will foam up and form a hard foam which is strongly insulating and therefore fire-retardant, and which protects the underlying polyester. The foam remains stable up to a temperature of 1089°C at which it eventually melts. An object formed from such fire-retardant polyester will retain its strength and load-bearing capacity in a fire for a long time. The above stated additive can also be used in synthetic materials other than polyester, particularly in other thermo-setting synthetic materials which will not melt and are highly form-retaining when exposed to heat.

Although the invention is further elucidated above with reference to only three embodiments, it will be apparent that the invention is in no way limited thereto. On the contrary, the invention paves the way for a person of ordinary skill in the art toward numerous variations and other embodiments, without this requiring an inventive contribution. Synthetic materials other than polyesters can thus also be provided with fire-retardant properties by adding a fire-retardant silicate thereto in the monomeric, at least not fully polymerized phase. An inherently fire-retardant insulating material can thus be obtained for instance by co-polymerization of polyol and poly-isocyanate with the addition of a suitable silicate compound. Instead of sodium silicate and sodium metasilicate other alkali metal silicates, such as potassium silicate and caesium silicate in particular, will provide at least comparable fire-retardant properties.

Claims

1. Synthetic material with fire-retardant properties, characterized in that a silicate compound is processed thereinto which forms foam at increased temperature.

2. Synthetic material as claimed in claim 1, characterized in that the synthetic material comprises a polymer and that the silicate compound is added as additive at the latest during a polymerization thereof.

3. Synthetic material as claimed in claim 2, characterized in that the silicate compound comprises an alkali metal silicate, in particular a sodium silicate.

4. Synthetic material as claimed in claim 3, characterized in that the silicate compound comprises a sodium silicate from a group of Na₂SiO₃.5H₂O and Na₂SiO₃.9H₂O.

5. Synthetic material as claimed in any of the foregoing claims, characterized in that it is a thermoset.

6. Synthetic material as claimed in any of the foregoing claims, characterized in that it comprises polyester.

7. Fire-retardant insulating material comprising a synthetic material as claimed in any of the foregoing claims in a foamed, form-retaining state.

8. Fire-retardant insulating material as claimed in claim 7, characterized in that the synthetic material is at least substantially constructed as mutually cohesive cores which are at least largely enclosed with a layer which contains a silicate compound and which forms foam at increased temperature.

9. Fire-retardant insulating material as claimed in claim 8, characterized in that the form-retaining state comprises a plate of stacked layers of the synthetic material which are glued together with interposing of the silicate compound-containing layer.

10. Fire-retardant insulating material as claimed in claim 7, characterized in that the silicate-containing compound is mixed at least almost homogeneously with the synthetic material.

11. Fire-retardant insulating material as claimed in claim 10, characterized in that the silicate compound is applied from a dry form by mixing grains or powder thereof with a basic synthetic material.

12. Method for making a synthetic material fire-retardant, characterized in that an additive containing a silicate compound which forms foam at increased temperature is added to the synthetic material.

13. Method as claimed in claim 12, characterized in that the additive contains a sodium silicate.

14. Method as claimed in claim 13, characterized in that sodium metasilicate, and in particular a silicate from a group of Na^iO^H^O and Na₂SiO₃.9H₂O, is added as additive.

15. Method as claimed in claim 12, 13 or 14, characterized in that the additive is added to the synthetic material in solid form, in particular as powder or grains.

16. Method as claimed in any of the claims 12-15, characterized in that 30-200% by weight of additive is added, calculated according to the quantity of the synthetic material.