A SHEET FOR USE AS A FLOOR SUBSTRUCTURE

Abstract: A sheet adapted for installation as substructure to a non-anchored floor comprises a laminate (1) of a moistureproof, shock absorbing and porous layer (2), a substantially gasproof layer (3) and a shock absorbing fibrous layer (4). The laminate is manufactured of a porous polymer material, a web of a gasproof foil and a web of fibre material. The webs are seamed together along the edges, where respective zones of the foil are in face to face contact. In this way, it is possible to obtain a barrier layer which is gasproof, impermeable to rising moisture and which has good properties regarding sound attenuation, shock absorption, heat insulation, and ease of installation.

Description: A sheet for use as a floor substructure This application is based on patent application No. 0287/97 filed in Denmark on 14 March 1997, the contents of which are incorporated herein by reference. Background of the invention 1. Field of the invention The present invention relates to a sheet for use as a floor substructure, and in particular to a barrier material adapted for use as a substructure for a non- anchored floor. The invention also relates to a laminate web for use in the manufacturing of a sheet of the above mentioned kind, to a method of manufacturing a sheet of this kind, and to a method of manufacturing a barrier layer for use as part of a floor substructure. In the present context, the term a non-anchored floor is used to designate a floor where the proper floor covering for being tread on is installed on top of a generally planar sub floor without any points of attachment or anchorings as opposed to floor coverings installed on top of and nailed to floor joists etc. The covering of a non- anchored floor may for instance comprise a wooden covering such as a parquet flooring whilst the sub floor may consist of a slab of concrete. The installation of a wooden floor covering directly on top of a concrete slab is associated with certain difficulties which must be dealt with in order to obtain a satisfactory result. The lack of resilience inherent to the concrete slab has the consequence that the floor may become uncomfortably hard to walk on unless some shock absorbing layer is interposed between the floor covering and the slab. The lack of resilience may also cause the degree of noise transmission to be higher than acceptable. In addition, the concrete slab may give off moisture from the surface due to the curing proces or due to moisture coming from underlying strata which may lead to a miscolouring or a change of dimensions of the floor covering. The moisture may also produce an unpleasant cooling effect. A growing concern about potentially dangerous gasses such as radon emerging from deep underground strata has furthermore prompted a growing demand for solutions, whereby a substantially gas-impervious barrier layer could be incorporated as part of a housing substructure, in particular in case of houses without a ventilated space below the floor. 2. Description of the Prior Art PCT/DK93/00248 contains a teaching of a sheet for use as a floor substructure which sheet generally consists of a fibrous layer in the form of cardboard treated on the lower side with a layer of bitumen which is treated on the respective lower side with a sound insulating layer comprising plastic spheres. The bitumen layer intercepts the rising moisture, thereby protecting the cardboard which degrades if exposed to moisture. Although this prior art material in many respects fulfils the requirements, it is, however, also associated with various drawbacks. The bitumen does not tolerate any significant heating, e.g. as may occur if the floor includes integrated heating elements. Spheres may separate from the sheet, creating difficulties to other procedures such as the assembly of tight-fit keys and grooves of parquet flooring elements. Finally, an increased awareness about potential risks due to gasses given off by substances such as bitumen has precipitated a desire to find replacement materials containing no such substances. From the marketplace an intermediate layer material is known which comprises a felt layer laminated with a polyethylene plastic foil. This material presents certain drawbacks. The foil is unprotected to one side and therefore susceptible to being damaged during handling or installation. If the material is installed turned with the foil facing downwards, irregularities, frequently present in a concrete floor, may perforate the plastic foil. The felt, if facing upwards, cannot be used for adhering anything on top, it cannot be used for the drawing of marking lines on top, and it is easily distorted and deformed by traffic on top. On the other hand, if the material is installed turned with the foil facing upwards, the foil risks being perforated due to working procedures, by traffic or by engagements with irregularities protruding from the lower side of the floor covering. The perforations may arise during the construction phase or during use due to the movements of the floor when treading on it. The foil if facing upwards presents an unpleasant surface and provides an uncomfortable working surface for the craftsmen who must finish the floor, it is unsuitable for adhesion of the floor covering and unsuitable for the drawing of marking lines etc. Summary of the invention The invention, in a first aspect, provides a sheet with the features according to claim 1. This sheet comprises a gas-impervious membrane useful for building a continuous, generally gasproof layer of intermediate layer material, capable of intercepting any rising gasses such as water moisture, radon etc. In the present context, the terms gas-impervious and gasproof are used to signify that the membranes or septums referred to, when subject to the conditions generally prevailing in a floor substructure, are capable of baffling permeation of gas to an extent where the migration of gasses such as water vapour is reduced by a noticeable extent, and preferably to a level where a wooden floor covering, installed on top will not be adversely affected by moisture permeating from below. The foil is protected on both sides making it feasible to select for the foil a sheet of minimal thickness without compromising the security that the foil stays intact throughout all handling and installation procedures as well as through its service life. The porous layer may comprise a felt of polymer material, e.g. a felt of polyamide, acryl, polypropylene or polyester with no substantial content of moisture sensitive ingredients. Suitable materials are available at reasonable cost as scrap from the textile industry. The porous layer has a shock absorbing and sound insulating capability and allows some ventilation and pressure equalizing along the surface of the sub floor. The fibrous layer may comprise a mix of fibres including cellulose fibres, e.g. from shredded cardboard which offers a durable and very comfortable surface and which possesses favourable qualities as regards shock absorption, sound insulation and thermal insulation etc. Suitable materials are available at reasonable cost as scrap from the cardboard industry. The mix of fibres may also include a proportion of plastic fibres, which tend to soften the product in order that it is easier rolled and unrolled. According to preferred embodiments, the fibrous layer or the porous layer is adhered onto the membrane by means of an adhesive bonding which covers partial surfaces interrupted by spaces without an adhesive bonding, so that the adhered area represents less than 20% and in particular less than 10% of the total area. The non adhered areas serve to make the product more flexible in order that is easily unrolled and laid down flat. This solves the problem of distortions etc. which may be a risk when combining thin layers of materials as different as cardboard and polymer. In particular, the adhesive bonding may be carried out with a hot fusible adhesive applied in stripes. A bonding of this kind may be carried out by simple working routines and at minimal cost of material. Similar lengths of web of intermediate layer material may be seamed together along the edges where the border zones of respective membranes are in overlying and surface bonded relationship, one on top of the other one. Thus, the seam presents double membranes but just a single top fibrous layer and a single bottom porous layer. Since the thickness of the membranes represents but a very small part of the total thickness of the sheets, the seam does not noticeably add to the thickness of the other portions of the sheet. The bonding of the membranes is conveniently implemented by means of a double faced adhesive tape applied on one foil border during an earlier stage or applied on the spot. The invention in another aspect provides a laminate web for use in the manufacturing of a sheet of the kind explained above, which laminate web comprises the features according to claim 7. This provides an advantageous barrier layer, which may be used for creating a gasproof septum suitable for use as part of a floor substructure. In a further aspect, the invention provides a method of manufacturing a sheet as indicated in claim 14. This method, allowing the layers to be joined by means of hot fusible adhesives, may be carried out in a simple manner and at a minimal cost of materials. The intermediate step where the porous layer pressed together with the adhesive foil are cooled before being joined with the fibrous layer serves the purpose of minimizing the risk of overheating the membrane and of causing distortions in the finished product due to temperature related dimensional changes. The method according to the invention, makes it feasible to use a thin foil of e.g. polyethylene which is by virtue of the narrow gauge sensitive to overheating as might otherwise occur during a procedure involving fusion by a hotmelt adhesive. Once sandwiched and protected between the porous layer and the fibrous layer, the polyethylene foil will safely sustain temperatures as high as 180°C, far in excess of any temperature expected, once the sheet is installed as part of a floor structure. In a still further aspect, the invention provides a method as recited in claim 17. By this method, it is possible to provide a gas-impervious barrier- layer for use as part of a floor substructure capable of barring penetration of gasses into the dwelling along this route. Brief description of the drawings The invention will be more fully understood from the appended description of preferred embodiments, explained with reference to the drawings where Fig. 1 shows a section in a laminate web according to the invention Fig. 2 shows a section of a floor with a barrier layer according to the invention, in an area, which includes a border seam between the two lengths of web, and Fig. 3 is a schematic depiction of a production line for the manufacturing of a web, implementing a method according to the invention. All drawings are schematic and simplified, only showing elements necessary for the sake of understanding the invention, while other elements have been excluded for the sake of clarity. The drawings are not necessarily to scale. The same references are used in all figures for designating identical or similar items. Description of the preferred embodiments Reference is first made to Fig. 1 showing a section in a laminate web 22. The laminate web 22 comprises a laminate 1, generally composed of a felt layer 2, a foil 3 and a fibrous layer 4, mentioned in the order taken from the bottom. The felt layer is adhered to the foil by the felt bonding 5 and the fibrous layer is adhered to the foil by the fibrous bonding 6. In the web, appropriate elements of this composition are so arranged that in the left side of Fig. 1, the porous layer is terminated short of the leftmost edge by a distance while in the right side of Fig. 1, the fibrous layer is terminated short of the rightmost edge by a distance. The left-hand border zone is designated by the reference 20, the right-hand border zone is designated by the reference 23. A double faced adhesive tape 7 with a peelable slip foil is applied to a face of the foil 3, situated along the right-hand border zone 23. According to a preferred embodiment, the web 22 is manufactured to a width of 110 cm with border zones to a width of 10 cm each. The foil may comprise a polyethylene foil, e.g. of a thickness of 40 μm. The felt layer may comprise a polypropylene felt e.g. in a quantity from 80 - 200 g/m 2 . The fibrous layer may comprise a mix of cellulose fibres and synthetic wool fibres, e.g. in a quantity from 100 - 400 g/m 2 . The total thickness of the web lies between 1 and 4 mm. Fig. 2 shows a section of a floor where lengths of the laminate web, according to the invention, has been used to build a barrier layer 18. This floor comprises a sub floor 17 made of a slab of concrete on top of which lengths of web 22 have been placed. The lengths of web are placed in juxtaposition and generally parallel and have been seamed along the edges where the border zones of the foils are in surface contact and adhered together by means of a double faced adhesive tape. On top of the barrier layer 18, the proper floor covering 19 has been applied, comprising e.g. a parquet flooring. The intimate joining of the lengths of web creates a coherent gasproof layer 18 which protects the dwelling interior against gasses likely to emanate from the concrete slab or from any underlying strata, e.g. radon gasses or water moisture. Figures 1 and 2 show, for the sake of clarity, thickness dimensions of the length intermediate layer material strongly exaggerated. In reality, the thickness dimensions of the materials are minute compared to the lateral dimensions. In particular, the foil is very thin. Therefore, it is possible to compile the seam joint in such a manner that the gasproof layer 18 obtains a substantially uniform thickness everywhere. In a very schematised way, fig. 3 shows a production line for the manufacturing of a web by a method according to the invention. A web of felt is dispensed from the felt roll 8 and is conveyed past a powder dispenser 11 which dispenses hot fusible adhesive, e.g. on a polyethylene basis and in a quantity of e.g. 8 - 10 g/m 2 . The web of felt is conveyed past the heat unit 12 which may comprise a radiation heat unit which serves the purpose of heating the powder adhesive to make it tacky on contact. The web of felt is brought together with a web of foil from the foil roll 9 in a unit comprising two closed loop teflon belts 14 travelling about guide rollers 13 and between platens 15, in order that the belts may be forced to compress the two webs in surface to surface contact to form a two-layer laminate. The platens 15 are equipped with cooling elements in order that they may cool the teflon bands and consequently also the two layered laminate substantially to room temperature before leaving the unit with the teflon bands. From the fibre roll 10, a fibre web is conveyed past a hotmelt dispenser 16 which applies narrow stripes of warm, tacky hotmelt on the fibre web. According to a preferred embodiment, adhesive is applied in stripes of each 5 mm, the distance between the stripes being approx. 10 cm. The applied quantity amounts to approx. 1 g/m of stripe or 10 g/m 2 within the stripe. The fibre web with the warm tacky stripes of adhesive is brought together with the two layered laminate in face to face contact with the adhesive stripes facing the exposed face of the foil web between two cooperating guide rollers 13, whereby the layers are adhered. The double faced adhesive tape covered on one face with a peelable slip foil is applied to the foil border zone by means not shown in the figure and the final product is collected onto the product roll 21. The modest amount of hotmelt dispensed on the fibre web does not cause any significant heating of the fibrous layer, thereby avoiding thermally related distortions in the final product. The only deformation to be corrected during the application is any residual bending remaining following unmangling of the product from the product roll 21. As this is a simple mangling, it is relatively easy to correct the form, e.g. by adhering a transverse stripe at each end of the unrolled web to the surface of the sub floor. Although preferred embodiments of the invention have been explained in some detail above, this explanation is offered solely for the purpose of facilitating the understanding of the invention, and with no intention of limiting the scope of protection thereof which is defined exclusively by the appended claims.

Claims: CLAIMS 1. A sheet adapted for installation beneath a floor covering, c h a r a c t e r i z e d by comprising a moisture tolerant, shock absorbing and porous layer, a substantially gas-impervious membrane and a shock absorbing fibrous layer, said membrane and said layers being bonded together in overlying relationship so as to form a laminate web wherein said membrane is sandwiched between said layers, said layers and said membrane being so arranged that said laminate web comprises a first border zone adjacent a first lateral edge, which is free of said porous layer and a second border zone adjacent a second lateral edge opposite said first lateral edge, which is free of said fibrous layer, in order that two similar lengths of said laminate web may be seamed together along respective edges, wherein the border zones of the respective membranes are arranged in overlying and surface bonded relationship, in order to provide a coherent and substantially gas-impervious barrier layer, wherein said membrane lies generally protected on both sides . 2. The sheet according to claim 1, c h a r a c t e r i z e d by said fibrous layer comprising cellulose fibres. 3. The sheet according to claim 1, c h a r a c t e r i z e d by said fibrous layer or said porous layer being bonded to said membrane by a surface bonding, which effectively covers only partial areas separated by spaces without effective bonding, the bonded partial areas constituting less than 20% and preferably less than 10% of the total area. 4. The sheet according claim 3, c h a r a c t e r i z e d by the bonding being effected by means of hotmelt adhesive applied in stripes. 5. The sheet according to claim 1, c h a r a c t e r i z e d by said porous layer comprising a felt of polymer material and by said layer being bonded to said membrane by means of a hotmelt adhesive, which has been applied onto said membrane in powder form. 6. The sheet according to claim 5, c h a r a c t e r i z e d by said laminate web being provided with a double-faced adhesive tape, applied onto the surface of said membrane along at least one of said border zones . 7. A laminate web for use in the manufacturing of a sheet according to any of the claims 1 through 6, c h a r a c t e r i z e d by comprising a moisture tolerant, shock absorbing and porous layer, a substantially gas-impervious plastic membrane and a shock absorbing fibrous layer, said membrane and said layers being bonded together in overlying relationship so as to form a laminate web wherein said membrane is sandwiched between said layers, said layers and said membrane being arranged so as provide said laminate web with a first border zone adjacent a first lateral edge, which is free of said porous layer and a second border zone adjacent a second lateral edge opposite said first lateral edge, which is free of said fibrous layer, in order that a length of said laminate web may be seamed together with a similar length of laminate web along respective edges, wherein the border zones of the respective membranes are arranged in overlying and surface bonded relationship, wherein generally all parts of said membrane lies protected on both sides. 8. The laminate web according to claim 7, c h a r a c t e r i z e d by said fibrous layer comprising cellulose fibres. 9. The laminate web according to claim 7, c h a r a c t e r i z e d by said fibrous layer being bonded to said membrane by a surface bonding, which effectively covers only partial areas separated by spaces without effective bonding, the bonded partial areas constituting less than 20% and preferably less than 10% of the total area. 10. The laminate web according to claim 7, c h a r a c t e r i z e d by the bonding being effected by means of hotmelt adhesive applied in stripes. 11. The laminate web according to claim 7, c h a r a c t e r i z e d by said porous layer comprising a felt of polymer material and by said layer being bonded to said membrane by means of a hotmelt adhesive, which has been applied onto said membrane in powder form. 12. The laminate web according to claim 7, c h a r a c t e r i z e d by said laminate web being provided with a double-faced adhesive tape, applied onto the surface of said membrane along at least one of said border zones. 13. The laminate web according to claim 1, c h a r a c t e r i z e d by being adapted for being stored prior to installation in mangled state. 14. A method of manufacturing a sheet adapted for installation beneath a floor covering, said sheet comprising a substantially gas-impervious membrane sandwiched between a moisture tolerant, shock absorbing and porous layer and a shock absorbing fibrous layer, c h a r a c t e r i z e d by comprising the steps of selecting a web of a porous, polymer material, a substantially gas-impervious foil web and a web of a fibrous material, - spreading onto one side of said web of porous material a hotmelt adhesive in powder state, - activating said hotmelt adhesive by heating it, - pressing together in a first compression stage said web of porous material with said foil web, - cooling off said webs while keeping them pressed together, in order to cure said adhesive and form a two- layered laminate web, treating said web of fibrous material with an activated, tacky, hotmelt adhesive, said adhesive being applied in a pattern that covers partial areas and leaves intermediate, untreated partial areas, and - bringing together said web of fibrous material with said two-layered laminate web with said web of fibrous material in face contact with said foil web and pressing them together in order to adhere them and to produce a laminate web of said sheet. 15. The method according to claim 14, c h a r a c t e r i z e d by said step of cooling off being furthered by using for the compression in said first compression stage platens provided with cooling means . 16. The method according to claim 14, c h a r a c t e r i z e d by comprising the further step of mangling said laminate web to form a product roll. 17. A method of manufacturing a shock absorbing, substantially gas-impervious barrier layer for use as part of a floor substructure, c h a r a c t e r i z e d by comprising the steps of - selecting lengths of a web manufactured according to the method of claim 14, - installing said lengths of web on top of the floor substructure in juxtaposition, in generally parallel arrangement with overlapping respective border zones, and - adhering together border zones of respective lengths of web in order to provide a substantially coherent, gas- impervious membrane.

Inventors: HARDER SVEN, HARDER, SVEN
Applicants: HARDER SVEN, ICOPAL AS, HARDER, SVEN, ICOPAL A/S
Application year: 1998
Main classification: E04F15
IPC codes: B32B5, E04F15