The present invention is concerned with layer structures and in particular, layer structures suitable for safety floor covering. There is a continuing need for improved safety covering surfaces for children's playgrounds, sporting areas and the like which provide impact resistance in a layer which is not of great thickness.

According to the present invention, there is provided a layer structure suitable for such uses, which comprises, in the order specified, an outer covering layer, a non- foamed substantially rigid load spreading sheet layer and at least one impact absorbing foam layer bonded to the undersurface of said load spreading layer, the surface of the layer structure remote from said load spreading layer being provided with a bottom layer of bonding adhesive suitable for bonding to a ground surface or the like.

The foam layer is typically bonded to the sheet layer by means of a hot melt adhesive. This is generally a thermoplastic synthetic hydrocarbon polymer based formulation, such as atactic polypropylene or other amorphous polyolefin, such as polybutene. The adhesive is preferably one which retains some tack at room temperature and is substantially incurable by means of elevated temperature alone. The adhesive should be hydrophobic and substantially free of hygroscopic ingredients, such that the layer structure is suitable for external use.

The hot melt adhesive may be applied by spraying, for example, largely as described in specification WO91 /00804; however, in a preferred embodiment, the polymer adhesive is spread on one or other of the surfaces to be adhered using a hot blade.

Typically, such a hot blade is at a temperature of about 190°C (for example, 180 to 200°C) such that the polymer contacting the face to which it is applied is at a rt temperature of about 90°C.

The load spreading layer is typically an integral body, which preferably ^~ " comprises an extruded plastics material such as PVC, polypropylene or the like, which in one embodiment is a unitary sheet member. In a further embodiment, the load spreading layer comprises:

(i) a first sheet member bonded to the undersurface of said outer layer; (ii) a second sheet member, spaced from, and substantially parallel to said first sheet member; and (iii) web means arranged to extend between facing surfaces of said sheet members, so as to partition the space between said sheet members into a plurality of chambers.

It is preferred that the web means comprise a plurality of discrete partition walls provided in a substantially vertical alignment relative to facing surfaces of the sheet members. It is further preferred that the partition walls are arranged as a plurality of substantially parallel rows, each row extending between opposed edge regions of the layer structure. The load spreading layer therefore typically comprises a plurality of substantially parallel passages which longitudinally extend between opposed edge regions of the layer structure, so as to provide continuous paths extending longitudinally through the load spreading layer of the structure.

The impact-absorbing foam layer is typically of closed cell foam of, for example, polyethylene. There is preferably at least two (such as three or more) of such impact-absorbing foam layers.

It is further preferred that a flexible foam layer is provided between the outer covering layer and the load spreading layer.

The bonding layer of adhesive (for bonding to a ground surface or the like) preferably provides a "peel and stick" layer where a peelable film layer is arranged to cover the adhesive; the bonding adhesive is preferably a pressure-sensitive material which is applied in a similar manner to the adhesive preferably used for bonding the layers together, as described above. The film part of the "peel and stick" layers is typically of polyethylene or PVC film.

The use of such peel and stick layers enables the layer structure according to the invention to be secured to a ground surface or the like.

A top layer or further layer of bonding adhesive is preferably provided for bonding the outer covering layer to the load spreading sheet layer; the top or further layer of adhesive typically comprises a pressure-sensitive adhesive as described above.

The outer covering of the layer structure typically comprises a known type of rubber crumb surfacing conventionally used in safety flooring. A layer structure comprising an outer rubber crumb surfacing is eminently suitable for outdoor use, such as patio

covering, swimming pool surrounds, impact absorbent surfacing for areas such as children's playgrounds, covering for golf driving areas (such as "winter tees"), and playing surfaces for games such as bowls, tennis, cricket, football and the like.

Alternatively, the outer covering layer may comprise a preformed fabric. Tre preformed fabric may be any suitable preformed (self-supporting) textile fabric, such as a tufted or woven fabric, which may be conventional Wilton or Axminster carpeting material. It is a particular advantage of the present invention that when the outer layer is patterned, the layer structures can be laid with good pattern matching between abutting units. The outer layer may have a pile, typically of depth 4 to 13mm.

A layer structure having a preformed fabric outer layer is particularly suitable for use as indoor floor covering and may be in the form of room-filling modules (that is, one such layer structure may cover substantially the entire floor area in a room). The layer structure may be used for other purposes such as, for example, vehicle floor covering or wall covering. Typical indoor floor coverings include coverings for children's play areas, indoor sport areas, or the like.

Typically, a layer structure according to the present invention may be in the form of tiles or other space filling shapes. It is preferred that a layer structure be provided with interlocking means capable of complementarily engaging with interlocking means provided on an adjacent layer structure. Preferred interlocking means comprise male and female engaging means, typically comprising complementarily shaped edge regions of the layer structures.

There is further provided by the present invention, a kit for use in providing a surface covering for an underlying surface, such as a floor area, which kit comprises:

(a) at least one layer structure substantially as hereinbefore described provided with first interlocking means; and

(b) at least one layer structure substantially as hereinbefore described provided with

<--* second interlocking means; wherein the first interlocking means is capable of complementarily engaging with the second interlocking means.

Preferred interlocking means comprise male and female engaging means comprising complementarily shaped edge regions of the layer structures.

There is further provided by the present invention a surface covering comprising a plurality of layer structures substantially as hereinbefore described.

There is still further provided by the present invention, an underlying surface (such as a floor area, wall or work surface) provided with layer structure, or surface covering, substantially as hereinbefore described.

The present invention will now be described in more detail with reference to the accompanying drawing (not to scale) in which Figures 1 to 4 are all exemplary layer structures according to the invention.

Referring to Figure 1 , the layer structure comprises a top film 1. an adhesive layer 2, a closed cell foam layer 3. a sheet layer 4 adhered to foam layer 3 by means of a further adhesive layer 5, and two further foam layers 6 and 7. in which layer 6 is bonded to the sheet layer by adhesive layer 8. and foam layers 6 and 7 are bonded to one another by adhesive 9.

The bottom surface of layer 7 is covered by layer of adhesive 10. which is itself covered by a layer of peelable film 1 1. In use. peelable film 11 is removed and the layer structure is adhered to the base of a previously excavated depression or a substantially flat surface: when the layer structure has been secured in place and it is desired to secure a top surfacing layer, the top film is then removed to allow the surfacing to be secured thereto.

Referring to Figure 2. there is shown a layer structure generally designated 21. comprising an outer rubber crumb layer 22, a load spreading layer 23, a foam layer 24 an adhesive layer 25 and film 25a.

Load spreading layer 23, comprises upper and lower sheets 26 and 27 respectively, and walls 28. Walls 28 connect sheets 26 and 27 and, although not shown in Figure 2. extend between opposed edge regions of the sheets 26 and 27. Sheets 26 and 27, and walls 28, typically comprise extruded polypropylene.

A suitable load spreading layer is tlie extruded plastics sheet material commercially available under the trade mark "Correx".

Layer 29 comprises an atactic polypropylene adhesive arranged as a continuous bonding layer between load spreading layer 23 and foam layer 24. Foam layer 24 comprises a closed cell , polyethylene foam.

Adhesive layers 25 respectively provide a bonding layers for outer layer 22 and film 25a.

Referring to Figure 3, there is shown a layer structure 30 which is a modification of layer structure 21 shown in Figure 2. Load spreading layer 23 of structure 30 comprises a single sheet of PVC material. PVC layer 23 is bonded to outer crumb surfacing 22 by pressure-sensitive adhesive 25, and to foam layer 24 by hot melt adhesive 29.

Figure 4 shows a layer structure 31 which is a modification of the layer structure 30 shown in Figure 3. Structure 31 comprises a plurality of foam layers 24 bonded to the undersurface of PVC layer 23. Foam layers 24 are bonded together by hot melt adhesive layers 29.

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