This invention relates to a plastic covering comprising polymeric alloy and intended for floor surfaces and wall sur¬ faces but preferably for floor surfaces, the polymeric alloy comprising a basic material in the form of PVC-plastic.

The use of plastic floors has lately become larger and larger. They are used in houses as well as in offices, schools and hospitals. Known plastic floors comprise a bottom layer which is made of softened PVC-material (PVC = polyvinyl- chloride) and a wearing layer comprising softened PVC-material PVC-plastic belongs to the group of thermoplasts, that i they become soft in heat and get stiff in cold. Thus, it is common to add a softening agent during the production of plastic coverings in order to make these ones sufficient flexible during use in normal room temperatur.

The softing agent being used today comprises phtalates, which have low molecular weight and are volatile. These phta¬ lates especially in combination with moisture emit substances which can be very annoying for allergic persons and others. This can be the case when laying a plastic covering on a newly made concrete floor which has not yet stiffened completely. In such cases the soft maker of the covering can react with the moisture such that injurious substances are emitted from the covering. Another drawback with known plastic coverings is tha the wear resistance of these ones is not sufficient in order t resist the wear that may occur for instance in schools and hospitals. Moreover, on known plastic coverings frictional hea can arise during the contact between the covering and an ob¬ ject, that is a local heating of the covering which can give ugly damages on the surface layer of the covering.

By Research Disclosure no. 258 (Oktober 1985) is pre¬ viously known a polymeric alloy comprising mixture of PVC- material and a thermo-setting polyurethane material, which is very expensive material. According to the document is the weight proportion of polyurethane considerably larger than the weight proportion of inexpensive PVC-material and can be up to 97%. Since this known polymeric alloy comprises a thermo- setting polyurethane material, the waste during the production cannot be used again, which contributes to the high production

cost for this type of plastic material.

In the material mentioned in Research Disclosure there is required an addition of organic solvents, which is injurious for the environment, in order that the material shall be kept floating during the production. This is a requirement in order that the material shall be able to be used as a coating agent on carrier materials like textile fabric and similar.

This invention intends to remove the problems with known technique. This has been made possible by a plastic covering of the kind mentioned by way of introduction which is character¬ ized in that at least that part of the covering which is in¬ tended to be directed outwards in a space, contains the poly¬ meric alloy, comprising of a mixture of the basic material and an alloying material, which is intended to make the basic ma- terial flexible, and which comprises thermo-plastic polyure¬ thane, and that the weight proportion of basic material exceeds the weight proportion of alloying material in the polymeric alloy. Due to that fact the need of phtalates as a soft maker is eliminated, wherefore the problems with emission of in- jurious substances are eliminated.

Furthermore, this new material comprises thermo-plastic polyurethane in contrast to the known material which comprises thermo-setting polyurethane. The new material becomes very durable and resistant to wear and less sensitive for frictional heat, wherefore the material becomes very suitable to be used as plastic coverings for instance for floors. Moreover, the main part of the material comprises the inexpensive PVC-plas¬ tic, and therefore the material becomes very inexpensive to produce. Another advantage with the new material depending on the fact that thermo-plastic polyurethane is used is that the waste material can be used again during the production of the material. In contrast to the material mentioned in Research Disclosure the new material herewith described is produced by- extrusion and calendering. As has been mentioned previously known plastic coverings for floors comprise a bottom layer intended to rest against a concrete floor, and a wearing layer intended to be treaded. In that connection both layers comprise a basic material of PVC containing a softening agent comprising phtalates.

The plastic covering according to the invention can be a least three different products.

Firstly, the plastic covering can be homogenous which means that the whole covering is made of the polymeric alloy and can be regarded as a single wearing layer. Thus, the basic material of the covering comprises PVC-plastic which has been mixed with an alloying material in the form of thermo-plastic polyurethane in order accordingly to form the new polymeric alloy. _ The second product may comprise two layers, one bottom layer and one wearing layer, each of which comprising the polymeric alloy. This means that compared with conventional coverings the softening agent containing phfalates has been replaced in both layers with an alloying material comprising thermo-plastic polyurethane.

The third product may also comprise two layers of which the bottom layer comprises a polymeric plastic which is made soft in a conventional way, while the wearing layer comprises the polymeric alloy according to the invention. Not either in this case there is any emission of phfalates into the space from the plastic covering, since the bottom layer comprising the conventional softening agent is covered by the wearing layer comprising the new innocuous plastic material.

The new polymeric alloy comprises PVC-plastic with a proportion of 60-80 weight% and thermo-plastic polyurethane with a proportion of 20-40 weight%. Especially good qualities are received if the polymeric alloy comprises 65-75 weight% PVC-plastic and 25-35 weight% thermo-plastic polyurethane- plastic. The invention is, of course, not limited to what has bee mentioned here. Thus, it is possible within the scope of the invention to produce a plastic covering comprising more layers than two. The important thing, however, is that the uppermost layer of the covering, that is the layer which is intended to be directed outwards in a space, shall contain the new poly¬ meric alloy.