Floor covering and underlayment

An underlayment for use in a floor covering, wherein the underlayment shows one or a combination of two or more of the following properties:

• the property that said underlayment comprises an underlayment basic layer, wherein said underlayment basic layer comprises fillers, wherein said underlayment basic layer is essentially free from fillers having a Moh's hardness of 7 or more and/or wherein said underlayment basic layer is essentially free from sand and/or wherein the majority of said fillers have a Moh's hardness of 5 or less, or of 3 or less, and/or wherein the majority of said fillers is formed by CaCO3 and/or talcum;
• the property that said underlayment comprises an underlayment basic layer, wherein said underlayment basic layer comprises filler particles, wherein said underlayment basic layer is essentially free from filler particles having a particle size larger than 500 micrometer, or, the 95th percentile of the distribution of particle sizes of particles available in said underlayment basic layer (8) is 500 micrometer or less. Alternatively, the average particle size or average particle diameter of the filler particles available in said underlayment basic layer, as defined by the d50 value of the particle size distribution, is between 50 and 500 micrometer, wherein said average particle size and said average particle diameters, and as said particle distribution and the d50 value and 95th percentile thereof is determined by the laser light scattering granulometry technique;
• the property that said underlayment basic layer is formed at least from a thermoplastic material being a crystalline or semi-crystalline material, such as polyethylene or polypropylene or a copolymer of polyethylene and/or polypropylene, having a melting temperature below 200° C., C;
• the property that the bottom of said underlayment is free from fibrous material;
• the property that the bottom of said underlayment is free from crystalline or semi-crystalline thermoplastic material having a melting temperature above 200° C.;
• the property that the bottom of said underlayment is formed by polyethylene;
• the property that the bottom of said underlayment is formed by a foil of polypropylene, including oriented polypropylene (OPP) or by a foil of polyethylene;
• the property that a foil is available above said underlayment basic layer, wherein said foil is manufactured from a thermoplastic material having a melting temperature of 235° C. or lower or of 200° C. or lower, and/or said foil is a foil of glycol modified PET (PETG) or a foil of polypropylene.