INSULATING MAT COMPRISING A MINERAL FIBRE LAYER

Abstract: A rectangular insulating mat comprising a mineral fibre layer made from a single unit of mineral fibre material, wherein the mineral fibres are bonded together by a binder and in which mineral fibre layer the fibres are predominantly located in planes substantially perpendicular to the plane of the mat, said mat being more easily compressible in the longitudinal or transverse direction than in the transverse or longitudinal direction, respectively, which mat further comprises an air permeable covering which covers at least the predominant part of the two main surfaces of the mat and which is attached to the mat.

Description: Insulating mat comprising a mineral fibre layer The present invention relates to a rectangular insulating mat comprising a mineral fibre layer made from a single unit of mineral * 5 fibre material, wherein the mineral fibres are bonded together by a jl binder and in which mineral fibre layer the fibres are predominantly located in planes substantially perpendicular to the plane of the mat, said mat being more easily compressible in the longitudinal or transverse direction than in the transverse or longitudinal 10 direction, respectively. Mats of the above mentioned type are i.a. used for the insulation of ceilings, walls and roofs and are advantageous in that they are shapable and consequently easy to adapt to the mounting sites. Thus, IS the mats can be mounted completely or partially without cutting, which is undesirable as it is labour-intensive and as loose fibres are thereby released to the environment. However, the prior art mats suffer from the drawback that when 20 compressed a relatively large amount of loose fibres are released to the surroundings together with the discharged air. As the mats are often mounted in relatively small, confined rooms the fibre concentration in the breathing air of the construction workers will therefore reach an undesirably high level. 25 Attempts have been made to enclose the mat with a loose, bag-shaped envelope. However, this solution has proved insufficient and inexpedient, vide below. 30 The object of the present invention is to provide an insulating mat of the type stated in the introductory part of claim 1 by which it is possible to reduce or eliminate the release of loose fibres to the surroundings caused by the compression of the mat. ■ ^ The above mentioned object is obtained with the insulating mat according to the invention, which is characterized in comprising an air-permeable covering which covers at least the predominant part of the two main surfaces of the mat and which is attached to the mat. Despite the fact that the mat according to the invention is compressible as described above a cutting of some of the mats in connection with their mounting can usually not be avoided. The mat according to the invention presents the advantage that due to the attachment of the covering to the mat only loose fibres from the cut surface formed will be released during the cutting of the mat. In contrast loose fibres from the entire surface of the mat are released during the cutting of a mat enclosed with a loose envelope, and this further involves the risk that the envelope will come off or be pulled off the mat completely. The fact that the covering is attached to the mat instead of having the form of a loose envelope furthermore presents the advantage that it becomes easier to handle the mat as it is easier to get a grip of the mat, and the risk of tearing up the covering and the mineral fibre material during handling is considerably reduced. Besides, it has surprisingly been found that the covering attached to the mat imparts an increased bending stiffness to the mat when the mat is located in a manner so as not to be fully supported and so that the covering is substantially stretched, e.g. located so as to be fixed between rafters in a slightly compressed state or located in such a manner that the ends of the mat rest on separate ceiling joists, in which case the mat will be deflected as a result of its own weight. In such cases the covering will serve to reduce the deflection degree of the mat to the extent that the covering is stretched or will be stretched during the incipient deflection of the mat. For comparison a loosely enclosing envelope will have no impact on the stiffness of the mat and, besides, such a covering will sag from a mat without a support, which is undesirable. Finally, the mat according to the invention is advantageous in that it has a far better feel than a uncovered mat. A commercially available mineral fibre product for the insulation of pipes, ducts and tanks comprises a rock fibre layer consisting of rod-shaped lamellae and an attached covering which on one main surface of the mat consists of heavy paper having a high air permeability and which on the other main surface of the mat consists of an air-permable layer of a non-woven material. The rock fibres are located in planes perpendicular to the plane of the mat. The mat according to the invention differs from the above mentioned prior art mat in that it is made from a single unit of mineral fibre material as opposed to a number of rod-shaped units, and that the entire covering is air-permeable and compressible in a direction parallel with the plane of the mat, whereas the prior art mat is compressible in the longitudinal direction of one of the main surfaces and rigid in the longitudinal direction of the other main surface, which properties make it suitable for covering curved surfaces. As used herein the term "mat" means a plate formed element. As used herein the term "air permeable covering" means a covering having an air resistance of less than 100 mm water column. The covering used preferably has an air resistance of less than 50 mm water column and more preferably less than 25 mm water column. As used herein the air resistance of a material is defined as the pressure drop across the material measured in mm water column when an air stream having a velocity of 0.186 m/s is conveyed towards the material in a direction perpendicular to the plane of the material. The covering material used should have such an air permeability that the velocity at which the compression of the mat is effected in connection with its use is not reduced noticeably as compared to an uncovered mat and that it allows the mat to be machine-packaged under compression. The mineral fibre material used for the mat according to the invention may be produced by converting a mineral melt into fibres, adding a binder to said fibres and causing them to form a fibre web which optionally is subjected to a vertical compression in order to arrange the fibres in planes parallel with the surface of the fibre web and subsequently subjecting the fibre web to a longitudinal compression to obtain a fibre web in which the fibres are predominantly located in planes substantially perpendicular to the plane of the mat. Such a fibre web is more easily compressible in the longitudinal direction than both in the vertical and transverse direction. Depending on whether it is desired to produce a mat with a maximum compressibility in the transverse direction or in the longitudinal direction, the fibre web is cut in such a manner that the longitudinal direction of the mat corresponds to the transverse and longitudinal direction, respectively, of the fibre web. In the above mentioned production method a heat curable binder is preferably used, in which case the vertical and longitudinal compression is effected before the fibre web is subjected to a heat treatment for curing the binder. The above mentioned production method is described in i.a. CH-620,861 incorporated herein by this reference. An alternative method of producing a mineral fibre material suitable for the mat according to the invention consists in folding a web of mineral fibre material, in which the fibres are located in planes parallel with the plane of the web, so as to form foldings extending parallel with the transverse direction of the web. The foldings may e.g. be formed by conveying the web through a cooperating pair of conveyor belts which are operated in such a manner that the conveyor belts having a fixed mutual spacing are caused to perform a vertical pendular movement of a constant amplitude at the outlet end. In this proces a waved web is formed which is conveyed through two pairs of consecutively located, cooperating conveyor belts, the latter pair being driven at a lower speed than the former pair, and by means of which a longitudinal compression of the waved web is effected so as to form a folded web. The above mentioned production method is described in i.a. DE-A-35 22 237 incorporated herein by this reference. As used herein mineral fibres mean rock wool fibres, glass fibres, slag fibres and similar synthetic fibres made from mineral starting materials. The mineral fibre material preferably consists of rock wool fibres and preferably has a density corresponding to a weight of between 15 kg/m 3 and 60 kg/m 3 . For a glas fibre material the density is preferably between 10 and 60 kg/m 3 . Any binder which is conventionally used in the production of mineral fibre products may be used as a binder. However, a modified or unmodified phenol resin, such as resol or novolak is preferably used. The covering may be applied directly to the mineral fibre material, e.g. by spraying, as described in i.a. international application No. PCT/DK93/00064. Alternatively the covering may be produced separately and subsequently be attached to the mineral fibre material by means of a layer of adhesive, by melting/welding or by sewing. The covering is preferably made of a non-woven organic or inorganic material. Examples of useful materials are materials of organic synthetic fibres, such as fibres of polyethylene, polypropylene, nylon and polyester. The covering may have the form of a gauze of such fibres, e.g. a gauze with a weight of between 5 and 100 g/m 2 . Also non-woven coverings made from natural fibres, such as fibres of cellulose, flax, coconut, hemp and the like, are useful. This also applies to coverings made from modified cellulose products, such as viscose and ryon fibres. As examples of useful non-woven inorganic materials, glas fibre gauze with a weight of between 10 and 100 g/m 2 made from glas fibres having a thickness of about 5-13 μm can be mentioned. Finally, the covering may be made from mixtures or combinations of one or more of the above mentioned materials. Perforated foils, such as a polyethylene or polypropylene foil having a weight of from 10 to 150 g/m 2 or a metal foil, such as an aluminium foil, may be used as covering material instead of non-woven materials. The perforated foil may have the form of a laminate, including a laminate consisting of a plastic foil and a paper layer or a plastic foil and a metal foil. The covering material optionally contains a fire retardent agent which may be any known fire retardent agent, such as fire retarders containing halogen compounds, phosphor compounds or substances containing water or releasing water when exposed to heat. Where a separately produced covering material is attached to the mineral fibre material by means of a layer of adhesive, said layer of adhesive may have the form of an air permeable, fully adhered layer, i.e. a layer covering substantially all the contact points between the covering material and the mineral fibre material, or it may have the form of separate zones of any form as well as bands, threads, stripes, dots or rows of dots. It is preferred to use an adhesive layer in the form of bands, stripes or rows of dots extending perpendicularly to the direction in which the mat is most easily compressible. Thus, with such an arrangement it is possible to prevent the provision of a covering from causing a reduction in the compressibility of the mat as the covering material will form regular, longitudinal foldings in the band-formed zones located between the bands, stripes and rows of dots, respectively, of adhesive during the compression of the mineral fibre material. Where a heat curable binder is used in the mineral fibre material, a preferred method of attaching the covering to the mineral fibre material consists in contacting pieces of the covering material with the surface of the mineral fibre material prior to the heat curing of the binder, and subsequently heat curing the binder. In this method the binder particles located close to the surface of the mineral fibre layer form bonds between the covering and the mineral fibre layer and thereby bind the former to the latter. The method presents the advantage that use of an adhesive can be avoided, and as a result thereof the calorific value of the finished mat is reduced and the fire properties of the mat is thus improved. Where a fully adhered covering is used, said covering is preferably made from a material having a high flexibility so that the covering does not reduce the compressibility of the mat to an unexpedient degree.

Claims: C L A I M S 1. A rectangular insulating mat comprising a mineral fibre layer made from a single unit of mineral fibre material, wherein the mineral fibres are bonded together by a binder and in which mineral fibre layer the fibres are predominantly located in planes substantially perpendicular to the plane of the mat, said mat being more easily compressible in the longitudinal or transverse direction than in the transverse or longitudinal direction, respectively, c h a r a c t e r i z e d in that it comprises an air permeable covering which coverings at least the predominant part of the two main surfaces of the mat and which is attached to the mat. 2. An insulating mat according to claim 1, c h a r a c t e r - i z e d in that the covering is made separately and subsequently attached to the mineral fibre layer by an adhesive layer. 3. An insulating mat according to claim 2, c h a r a c t e r ¬ i z e d in that the adhesive layer has the form of bands, stripes or rows of dots extending perpendicularly to the direction in which the mat is most easily compressible. 4. An insulating mat according to claim 2, c h a r a c t e r ¬ i z e d in that the adhesive layer has the form of an air permeable, fully adhered layer. 5. An insulating mat acording to any of the preceding claims, c h a r a c t e r i z e d in that the binder is a heat curable binder.

Inventors: CLAUSEN ANDERS ULF, NOERGAARD LUIS JOERGEN, CLAUSEN, ANDERS, ULF, NOERGAARD, LUIS, JOERGEN
Applicants: CLAUSEN ANDERS ULF, NOERGAARD LUIS JOERGEN, ROCKWOOL INT, CLAUSEN, ANDERS, ULF, NOERGAARD, LUIS, JOERGEN, ROCKWOOL INTERNATIONAL A/S
Application year: 1995
Main classification: E04B1
IPC codes: D04H13, E04B1, E04C2