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  Process for reducing radon inside buildingsUSPTO Application #: 20070218832Title: Process for reducing radon inside buildings Abstract: A process for reducing radon inside a building whose inner atmosphere is susceptible to radon accumulation is disclosed herein. The process involves, application of a composition including a crosslinkable epoxy resin of bisphenol A type and a crosslinking agent to a structural component of the building. The composition is applied in an amount corresponding to a surface density of the resin between 300 and 1300 g/m2. (end of abstract) Agent: Hunton & Williams LLP Intellectual Property Department - Washington, DC, US Inventor: Georges Robert Lacoste USPTO Applicaton #: 20070218832 - Class: 454341000 (USPTO) Related Patent Categories: Ventilation, Having Outlet Airway, With Air Pump The Patent Description & Claims data below is from USPTO Patent Application 20070218832. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] The present invention relates to a process for reducing radon inside buildings. [0002] Radon is a radioactive gas of natural origin arising from the disintegration of the uranium and radium contained in the Earth's crust, and which is naturally present in variable amounts depending on the region and the type of soil. [0003] It is present throughout the entire surface of the Earth and particularly in regions with granitic and volcanic subsoil, and can migrate from the soil into the atmosphere, where it tends to accumulate in enclosed spaces, and especially in buildings. [0004] The presence of radon in the air inside buildings thus results from the level of formation of this gas in the soil, but also from the characteristics of the surface of the building in contact with the soil, and especially of the presence of cracks, holes and/or porosity. [0005] The presence of radon is of particular concern for buildings in which people reside over long periods (dwellings, schools or public establishments). This radioactive gas can in fact reach concentrations in the air that are liable to represent a risk factor for lung cancer to the occupants of the buildings, more particularly in the case of simultaneous exposure to tobacco. [0006] This is why public authorities are concerned about limiting the average annual concentration of radon in buildings. Thus, the European Union recommends that new buildings should be designed such that this average annual concentration does not exceed 200 Becquerel per m.sup.3 (Bq/m.sup.3). France has adopted a value of 1000 Bq/m.sup.3 as the alarm threshold, and 400 Bq/m.sup.3 as a warning level. [0007] Processes for reducing the concentration of radon in the air inside buildings already exist. [0008] The renewal of air can thus be increased by means of natural or mechanical ventilation, which has little effect on changing the penetration of radon into the building, but promotes the dilution and evacuation of the gas. [0009] Other treatments consist in acting at the interface between the soil and the building to prevent the entry of radon originating from the soil. Attempts have thus been made to use plastic groundsheets to cover the soil. However, these groundsheets do not allow hermetic sealing capable of completely preventing radon from escaping from the soil into the building. [0010] Chemical treatments of the interface between the soil and the building have also been envisaged. U.S. Pat. No. 5,399,603 thus describes the use of an emulsion containing a sulfopolyester, an acrylic copolymer and a plasticizer. [0011] It is moreover known practice in the construction field to use crosslinkable epoxy resins of bisphenol A type (i.e., a bisphenol A crosslinkable epoxy resin), for the preparation of cement- or concrete-based supports that are subject to capillary rising of moisture from the soil, optionally prior to the application of leveling coats (also known as resurfacing coats) for the laying of floor coverings such as parquets, carpets, linoleum or floor tiles. BRIEF SUMMARY OF THE INVENTION [0012] One aim of the present invention is to propose another method for the chemical treatment of the interface between the soil and the building, which makes it possible to substantially reduce the concentration of radon inside buildings, and especially to improve the impermeability to this gas of the parts of buildings that are in contact with or in the region of the soil. [0013] Another aim of the present invention is to propose treatment for simultaneously obtaining a reduction in radon inside a building and for improving the impermeability to moisture of the parts of the building that are in contact with or in the region of the soil. [0014] It has now been found that these aims are totally or partly achieved by applying a limited surface density, which is within a specific range, of crosslinkable epoxy resin of bisphenol A type. [0015] According to an embodiment of the invention, a process is disclosed for reducing radon inside a building susceptible to radon accumulation. The process includes a step of applying to at least an inner surface of a structural component of the building a composition comprising a crosslinkable epoxy resin of bisphenol A type (i.e., a bisphenol A crosslinkable epoxy resin) and a crosslinking agent. The composition is applied in an amount corresponding to a surface density of the resin of between 300 and 1300 g/m2, and preferably between 400 and 950 g/m.sup.2, and most preferably between 450 and 950 g/m.sup.2. In one application the structural component is a concrete base slab covered with a screed. [0016] The process is particularly suitable for buildings that have an inner atmosphere which is capable of reaching a radon concentration greater than 100 Bq/m.sup.3, greater than 200 Bq/m.sup.3, greater than 400 Bq/m.sup.3, or greater than 1000 Bq/m.sup.3. In addition, the process is preferably performed on buildings in which people reside over long periods or public establishments. [0017] The crosslinkable epoxy resin of bisphenol A type is preferably obtainable by reacting halo epoxides with bisphenol A, bisphenol AD or bisphenol F. Moreover, the crosslinkable epoxy resin of bisphenol A type is preferably a mixture of bisphenol A diglycidyl ether and of bisphenol F diglycidyl ether. In an embodiment of the invention, the crosslinking agent is a mixture of a modified polyamide and of an aliphatic polyamine. Preferably, the ratio of the weight of crosslinkable epoxy resin of bisphenol A type to the weight of crosslinking agent is between 0.1 and 10, and more preferably between 1 and 2. BRIEF DESCRIPTION OF THE DRAWINGS [0018] FIG. 1 illustrates an apparatus for measurement of the efficacy of reduction of radon emission. DETAILED DESCRIPTION OF THE INVENTION [0019] One subject of the present invention involves a process for reducing radon inside a building whose inner atmosphere is capable of reaching a radon concentration of greater than 100 Becquerel per m.sup.3, the process comprising the application to the inner surface of a component of the structure of the building, placed in contact with or in the region of the soil, of a composition comprising a crosslinkable epoxy resin of bisphenol A type and a crosslinking agent, the composition being applied in an amount corresponding to a surface density of the resin of between 300 and 1300 g/m.sup.2 and preferably between 400 and 950 g/m.sup.2. [0020] The present process thus concerns buildings whose inner atmosphere is capable of reaching a radon concentration of greater than 100 Becquerel per m.sup.3 (Bq/m.sup.3). Such a concentration--corresponding to an annual average--generally results from an accumulation, in the case of a confined atmosphere, of the radon that diffuses into the air from the soil or from water, for buildings constructed in a region whose subsoil is of granitic and/or volcanic nature. In the case of France, for example, the regions that are most concerned are Brittany, Corsica, the Massif Central and the Vosges. The determination of the concentration of radon in the air is performed by means of known measurements of radioactive disintegrations of radon atoms, using a dosimeter. Continue reading... Full patent description for Process for reducing radon inside buildings Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Process for reducing radon inside buildings patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. 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