RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 61/887,314, titled COATINGS FOR ATTENUATING IONIZING RADIATION, COATED SUBSTRATES AND ASSOCIATED METHODS, filed on October 4, 2013, which is hereby incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] This disclosure relates generally to coatings that attenuate ionizing radiation and, more specifically, to coatings that include a curable binder throughout which a radio-opaque material is dispersed. In more specific embodiments, the coatings may comprise paints that are formulated to attenuating ionizing radiation. This disclosure also relates to methods for coating substrates to attenuate ionizing radiation emanating therefrom, as well as to substrates to which one or more ionizing radiation-attenuating coatings have been applied.

DISCLOSURE

[0003] A coating that attenuates ionizing radiation may include a binder and a component that attenuates ionizing radiation, which is also referred to herein as an "ionizing radiation attenuating component."

[0004] The ionizing radiation attenuating component of a coating may comprise a radio-opaque material. The radio-opaque material may be non-toxic (e.g., does not pose a health risk to humans or animals, etc.) and/or non-hazardous {e.g., does not pose a threat to surfaces to which it is applied or nearby structures, etc.).

[0005] In some embodiments, the radio-opaque material may be based on an elemental species having an atomic number of at least 50. In other embodiments, the radio-opaque material may be based on an elemental species having an atomic number of 56 or greater. Examples of elements meeting these criteria include, but are not limited to, barium, bismuth and lanthanum. The radio-opaque material may comprise the elemental form {e.g., a metal, etc.) of such an element. Alternatively, or in addition, the binder may comprise a chemical compound {e.g., a molecular compound, a salt, an intermetallic compound or a complex). Some non-limiting examples of these types of chemical compounds include barium sulfate, bismuth oxide and lanthanum oxide. As another alternative, the radio-opaque material of the ionizing radiation attenuating component of a coating according to this disclosure may include one or more elemental forms of a material that acts as a suitable attenuator of ionizing radiation, as well as one or more chemical compounds that are based on one or more elemental species that have acceptable ionizing radiation-attenuating characteristics.

[0006] The binder of a coating according to this disclosure may comprise a material such as a resin or a polymer. In some embodiments, the resin or polymer may be in a curable form (e.g., in a flowable form, in liquid form (e.g., capable of being sprayed, powder coated, brushed, rolled, printed, etc., onto a substrate), etc.), or it may have already cured. As used herein, the terms "cure," "cured" and "curing" refer to a variety of processes by which a binder, such as that commonly used in paint or another coating, binds together and to a surface to which the coating is applied. Without limitation, curing processes may include coalescence (e.g., by drying, solvent evaporation, etc.), polymerization or the like. In embodiments where the binder cures by polymerization, the binder may comprise a one-part chemical system. In such an embodiment, a non-chemical external factor, such as heat, radiation or the like may initiate the process of polymerization. In other embodiments, the binder may comprise a two-part binder, which may polymerize as two chemical compounds are mixed with each other (e.g., as a chemical catalyst is mixed with the polymerizable material, etc.).

[0007] Some non-limiting examples of materials that may be employed as a binder of a coating according to this disclosure are aqueous emulsions (e.g., so-called "latex" paints, etc.), lacquers, acrylics, vinyl-acrylics, polyurethanes, epoxies, oils, polyesters, alkyds, vinyl acetate/ethylenes, melamine resins, and the like.

[0008] A variety of coating formulations are within the scope of this disclosure. A coating may be formulated to enable its application to a substrate in a desired manner (e.g., by spraying, powder coating, rolling, brushing, dip coating, etc.) while providing a desired level of ionizing radiation attenuation. Without limitation, a radio-opaque material may comprise about 20% or more of the total weight of an uncured coating according to this disclosure. Alternatively, the radio-opaque material may comprise about 50% or more of the total weight of an uncured coating. Of course, as the coating cures, the proportion of the weight of the radio-opaque material to the weight of the cured coating may increase. A radio-opaque material may account for about 40% or more of the weight of a cured coating. In some embodiments, the radio-opaque material may account for about 85% or more of the weight of the cured coating.

[0009] When a layer of the coating is spread onto a surface of a substrate, it may attenuate at least some ionizing radiation emanating (e.g., passing through, fluorescing from, reflected from, etc.) that surface. The extent to which a coating may attenuate ionizing radiation may be a function of the type and/or amount of the radio-opaque material present in the coating, as well as a function of the thickness of the coating once it has cured.

[0010] In use, a coating may be applied to a substrate. A coating may be applied as a single layer (e.g., one coat) or as a plurality of superimposed layers (e.g., a primer and one or more coats, a plurality of coats, etc.). When different layers of a coating, or different coatings, are applied to a surface of a substrate, they may include the same types of binders as each other (e.g., primers, epoxies, paints, etc.) or they may include different types of binders from one another.

[0011] Similarly, different coatings may include the same radio-opaque material, or they may include different radio-opaque materials. Without limitation, a first coating may comprise a first radio-opaque material based on a first elemental species having a first atomic number, while a second coating may comprise a second radio-opaque material based on a second elemental species having a second atomic number.

[0012] The first and second atomic numbers may be the same, in which the case the first and second radio-opaque materials may be the same or the first and second radio- opaque materials may be different (e.g., one may comprise an elemental form while another may comprise a chemical compound, they may comprise different chemical compounds, etc.).

[0013] Alternatively, the first and second atomic numbers may differ from one another. In a specific embodiment, the first coating may be located closer to, or face, a direction from which ionizing radiation is or will be transmitted, while the second coating may be positioned farther away from, or face away from, the direction from which the ionizing radiation is or will be transmitted. Even more specifically, in such an embodiment, the first atomic number may be less than the second atomic number. In such an embodiment, the first radio-opaque material may be a relatively low-z material, while the second radio-opaque material may be a relatively high-z material. With such an arrangement, the first coating may be configured to attenuate relatively high energy ionizing radiation, while the second coating may be configured to attenuate lower energy ionizing radiation, which lower energy ionizing radiation, or fluorescent ionizing radiation, may result from attenuation of the relatively high energy ionizing radiation.

[0014] Any suitable means may be used to apply a coating to a substrate. Various techniques by which a coating may be applied to a surface of a substrate include, but are not limited to, spraying, powder coating, rolling, brushing, printing and dip coating. Of course, those means may vary with one or more of the type of coating being applied {e.g., liquid (and its viscosity), powder, etc.), the environment and/or context in which the coating is applied and the location on the substrate to which the coating is applied.

[0015] Depending upon the substrate and the manner in which ionizing radiation may emanate from one or more of its surfaces, a coating may be applied to exterior surfaces, to interior surfaces or to a combination of exterior and interior surfaces.

[0016] A coating may be selectively applied to a surface. Selective coating may be enabled by use of a mask, a screen, or the like. Alternatively, selective coating may be effected by selective processes, such as by directing a focused spray onto desired portions of the surface of a substrate. Alternatively, a coating may be non-selectively applied to a substrate and, thus, comprise a conformal coating or a blanket coating.

[0017] Examples of various substrates to which a coating may be applied include, without limitation, objects that are present in a particular setting, such as structures (e.g., pipes, valves, etc.) that convey sources of ionizing radiation (e.g., radioactive waste, etc.), equipment from which ionizing radiation may originate, objects that are likely to reflect or fluoresce ionizing radiation, housings or enclosures for any of the foregoing, and other objects with surfaces from which ionizing radiation is likely to or may emanate. Other examples of substrates include architectural features, such as floors, walls, ceilings, doors, windows, panels and the like.

[0018] A substrate may include one or more surfaces that carry one or more coatings. The coating(s) may include a binder in a cured (e.g., coalesced (or dried), polymerized, etc.) form, as well as a radio-opaque material dispersed throughout the binder. In some embodiments, the coating may comprise a single layer. In other embodiments, the coating may include two or more layers, which may include the same radio-opaque material or different radio-opaque materials.

[0019] Other aspects, as well as various features and advantages, of the disclosed subject matter should be apparent to those of ordinary skill in the art from the foregoing disclosure and the appended claims.