Sports floor

Abstract: A general-purpose sports floor is installed on a supporting substructure composed of stone-like materials or other compositions of materials such as a wooden floor or stabilized sand. In order that the sports floor meets the highest requirements with respect to sports serviceability, lowest risk of injury to the sportsman or sportswoman, mechanical strength and durability it is composed at least of a combination of the following layers or composite layers: 1. at least one relatively thin polyurethane top layer (3) with a covering (2) producing friction for the sportsman or sportswoman; 2. at least one hard elastic layer (4) formed from granules or rubber particles and air cavities present between said particles; 3. at least one relatively thin force-distributing hard layer (5) made, for example, of plywood or hard plastic; 4. at least one relatively thick layer (8) made of plastic foam.

Description: The invention relates to a sports floor installed on a cohesive substructure or sand layer comprising: at least one hard elastic layer including rubber granules, and at least one upper layer of plastic material. Such a sports floor is disclosed in DE-A-1952114. This known sports floor is suitable for running sport only. If sports like basketball and volleyball are played on such a floor, the players carry a risk of damaged knees and ankles. General-purpose sports floors are suitable, for example, for playing, for example, volleyball, basketball, handball, korfball, indoor football, indoor hockey or badminton or practising gymnastics thereon. According to standards of the Dutch Sport Federation (DSF), general-purpose indoor sports floors are divided into three different categories. The category 1 sports floor has to meet the highest requirements, inter alia with respect to shock absorption, running comfort, friction generated by the surface, static and dynamic mechanical strength, durability under continuous load, resistance to wear, resistance to climatological factors and ball behaviour. In particular, the floor must not feel either too hard or too soft, it must offer adequate friction for sports shoes both in the dry and wet state, lateral takeoff must not be impeded and the damping, i.e. the reduction in the impact force, must become higher, the higher the speed at which the sportsman or sportswoman strikes the floor. Moreover, the floor must not, or virtually not, continue to vibrate after an impact and the sportsman or sportswoman must not feel the floor give under his or her feet during normal running. The German DIN Standard 18 032 also specifies requirements imposed on indoor sports floors. The object of the invention is to provide a sports floor which meets the standards of a general-purpose indoor sports floor of category 1 of the Dutch Sports Federation (code NSF-US1-1). Said sports floor must meet the highest requirements with respect to sports serviceability, lowest risk of injury to the sportsman or sportswoman, mechanical strength and durability. According to the invention the sports floor as indicated in the preamble is characterized in that said hard elastic layer is positioned on a force distributing hard layer made for example of plywood or hard plastic and having a thickness between 6 and 20 mm and a density between 350 and 800 kg/m³, that said force distributing hard layer is positioned on at least one layer of plastic foam having a density between 30 and 200 kg/m³ and a thickness of at least 12 mm, that the upper layer is made of polyurethane and has an antifriction covering, and that between the rubber granules of the hard elastic layer air cavities are present. Very good results with respect to shock absorption are achieved if the top layer is composed of two polyurethane layers each having a thickness of 1 mm and a density of 1340 kg/m³, if the layer of rubber granules has a thickness of approximately 9 mm, a modulus of elasticity of 21 MPa and a density of 870 kg/m³, if the force-distributing layer is composed of two layers of waterproof plywood mutually bonded by flexible polyurethane glue and each having a thickness of approximately 6 mm and if the foam layer is composed of one or more layers of identical or different density and has a thickness of approximately 30 mm. Further limits and preferred values of parameters of the different layers follow from the description and subordinate claims. In order to be able to match the degree of shock absorption of the sports floor to the sport to be practised, the plastic foam may be packaged in airtight plastic bags which are connected to one another and/or to a pressure vessel and/or to a pump via one or more hoses, valves which can be operated being installed in the bags and/or the connecting hoses in order to be able to bring about and/or to be able to eliminate the pressure differences in a particular manner, for example, inter alia, depending on the sport to be practised on the sports floor. The invention will now be explained in more detail with reference to the figures. Figure 1 shows a section of a preferred embodiment of a sports floor according to the invention. Figure 2 shows a graph in which the percentage of damping is plotted against a force exerted on the sports floor. The sports floor shown in Figure 1 is installed on a concrete floor 1 and is composed, viewed from top to bottom, of the following layers: a layer 2 approximately 1 mm thick and composed of polyurethane having a density of 1350 kg/m³ and having a polyurethane finishing layer which brings about the generated friction needed for the sportsman or sports-woman under moist conditions, for example due to shed droplets of sweat, and dry conditions; a layer 3 approximately 1 mm thick composed of polyurethane and having a density of approximately 1350 kg/m³; a hard elastic layer 4 composed of granules of rubber particles bonded to one another by polyurethane glue, which layer has a thickness of approximately 9 mm; there are air cavities between the particles; the density is approximately 870 kg/m3 and the modulus of elasticity approximately 21 MPa; the top of said layer is generally provided with a surface-filling layer; a force-distributing hard layer 5 composed of waterproof plywood having a thickness of approximately 6 mm and a modulus of elasticity of 4300 MPa; a very thin layer of flexible polyurethane glue (7); a force-distributing hard layer 6 composed of waterproof plywood having a thickness of approximately 6 mm and a modulus of elasticity of 4300 MPa, the layers 5 and 6 being composed of panels which are offset with respect to one another so that the force distribution is also optimum in the case of connecting seams; a layer 8 composed of polyurethane-bonded polyether foam having a thickness of 15 mm and a density of 120 kg/m³; a layer 9 composed of polyurethane-bonded polyether foam having a thickness of 15 mm and a density of 80 kg/m³. Said sports floor meets the standards of the Dutch Sports Federation for a general-purpose sports floor of category 1. The following tables give an impression of the properties of the sports floor described above. FIRE RESISTANCE Low flammability The running comfort, the shock absorption, the static and dynamic strength and the durability under continuous loading of the sports floor according to the invention were assessed as very good. Figure 2 shows graphically the shock absorption, specified as damping capacity in DSF reports, in % plotted against the force exerted. The region between the broken lines is the region within which the percentage of shock absorption of category 1 floors must fall. In order to achieve adequate results, the following limits are specified: layer of rubber granules 4: thickness 4 to 14 mm and density 500 to 1000 kg/m³. Force-distributing layer 5, 6, 7: thickness 6 to 20 mm and density 350 to 800 kg/m³, preferably 490 to 535 kg/m3. Foam layer 8, 9: thickness 12 to 50 mm and density 30 to 200 kg/m³. The foam layers 8, 9 may be packed in airtight plastic bags which are connected via one or more hoses to a pressure vessel or pump. The bags may be mutually connected. By bringing the bags to a particular pressure, the shock absorption provided by the floor can be matched to the type of sport. Pressure differences can be achieved or eliminated in a particular manner, which is dependent, inter alia, on the sport to be practised, by means of valves in the bags and/or the hoses. The sports floor according to the invention has, inter alia, the following advantages: the floor does not feel too hard but the sportsman or sportswoman does not have the feeling of sinking into the top layer. the floor can provide the sportsman or sportswoman with adequate friction, both in the dry and in the moist state. lateral take-off is not impeded. during descent after a jump, the floor feels such that the impact is absorbed as well as possible; the higher the speed at which the sportsman or sports-woman strikes the floor, the greater is the reduction of the impact force, the term reduction of the impact force being synonymous with damping in sports circles. the shock absorption or, alternatively, the reduction of the impact force must be such that the movement of the sportsman or sportswoman, for example during jumping, is not deadened, but such that speed always continues to exist in the sport and that the forces exerted on the sportsman or sportswoman can be kept as low as possible. if a sportsman or sportswoman jumps on a floor, the after-vibration will hardly be capable of being felt by another sportsman or sportswoman.

Claims: Sports floor installed on a cohesive substructure or sand layer comprising: at least one hard elastic layer (4) including rubber granules, and at least one upper layer (3) of plastic material, characterized in that said hard elastic layer (4) is positioned on a force distributing hard layer (5, 6) made for example of plywood or hard plastic and having a thickness between 6 and 20 mm and a density between 350 and 800 kg/m³, that said force distributing hard layer (5, 6) is positioned on at least one layer of plastic foam (8, 9) having a density between 30 and 200 kg/m³ and a thickness of at least 12 mm, that the upper layer (3) is made of polyurethane and has an anti-friction covering (2), and that between the rubber granules of the hard elastic layer (4) air cavities are present. Sports floor according to Claim 1, characterized in that the polyurethane in the upper layer (3) has a density of between 1000 and 2500 kg/m³. Sports floor according to Claim 1 or 2, characterized in that the upper layer (3) is installed in the liquid state on the hard elastic layer. Sports floor according to any of the preceding claims, characterized in that the polyurethane upper layer (3) is composed of two layers approximately 1 mm thick. Sports floor according to any of the preceding claims, characterized in that the layer (4) of rubber granules has a thickness of between 4 and 14 mm and a density of between 500 and 1000 kg/m³. Sports floor according to Claim 5, characterized in that the modulus of elasticity of the layer (4) of rubber granules is approximately 21 MPa and the density approximately 870 kg/m3. Sports floor according to either Claim 5 or 6, characterized in that the layer (4) of rubber granules has a thickness of approximately 9 mm. Sports floor according to any of Claims 5-7, characterized in that the rubber particles of the layer (4) of rubber granules are bonded to one another by means of polyurethane glue. Sports floor according to any of Claims 5-8, characterized in that the top of the layer (4) of rubber granules is provided with a surface-filling layer. Sports floor according to any of the preceding claims, characterized in that the force-distributing hard layer is composed of two layers (5, 6) of waterproof plywood, the parts of which are glued to one another in a manner such that they are offset with respect to one another. Sports floor according to any of the preceding claims, characterized in that the force-distributing hard layer is composed of two layers (5, 6) of plastic, the parts of which are glued to one another in a manner such that they are offset with respect to one another. Sports floor according to any of the preceding claims, characterized in that the force-distributing hard layer (5, 6) is composed of a plastic layer. Sports floor according to any of Claims 10-12, characterized in that the modulus of elasticity of the force-distributing layer (5, 6) is approximately 4300 MPa. Sports floor according to Claim 13, characterized in that the density of the force-distributing layer (5, 6) is between 490 and 535 kg/m³. Sports floor according to one of the preceding claims, characterized in that the foam layer is composed of two layers (8, 9) of polyurethane foam, of which one (8) has a thickness of approximately 15 mm and a density of approximately 120 kg/m³ and the other (9) has a thickness of approximately 15 mm and a density of approximately 80 kg/m³. Sports floor according to any of the preceding claims, characterized in that there is installed beneath the said four layers an assembly of layers which, viewed from top to bottom, is composed of a force-distributing hard layer having a thickness of 3 to 20 mm and a foam layer having a thickness of 12 to 50 mm. Sports floor according to any of the preceding claims, characterized in that the plastic foam is packaged in airtight plastic bags which are mutually connected to one another and/or to a pressure vessel and/or to a pump via one or more hoses. Sports floor according to Claim 17, characterized in that valves which can be operated are installed in the bags and/or connecting hoses.

Inventors: BLOM JAN, BLOM, JAN
Applicants: HOLLANDSCHE BETONGROEP NV, HOLLANDSCHE BETON GROEP N.V.
Application year: 1991
Main classification: E04F15
IPC codes: B32B7, E04F15