Radiation shielding compositions for protection against x-rays

Abstract

Compositions are described that can protect against X-rays generated from X-ray tubes with voltages of 50kV to 150 kV. The compositions can include, for example, transition metal particles dispersed in a polymer matrix. The transition metal particles can be present at 70% by weight or more based on the weight of the composition. Methods of using the compositions to form sheets that can provide a selected lead equivalence value are also described.

Description

BURLMED-7003WO RADIATION SHIELDING COMPOSITIONS FOR PROTECTION AGAINST X-RAYS

[0001] PRIORITY APPLICATION

[0002] This application is related to, and claims priority to and the benefit of, U.S. Provisional Application No. 63 / 673,488 filed on uly 19, 2024, the entire disclosure of which is hereby incorporated herein by reference.

[0003] TECHNOLOGICAL FIELD

[0004] Certain configurations are described for lead-containing and lead-free elastomeric radiation-protective compositions that can be used in protective articles and other articles to protect against radiation such as, for example, primary X-rays and scattered X-rays.

[0005] BACKGROUND

[0006] X-rays are often used in various medical imaging and interventional procedures. Gamma rays are also used in medicine (e.g. radiotherapy), but also for sterilization and disinfection, as well as in the nuclear industry. Exposure to ionizing radiation (X rays and gamma rays) imposes health risks for the patients, the medical staff (doctors, nurses, operators) and the industry operators working around the gamma rays, resulting in an increased likelihood of numerous disorders and diseases. Ionized radiation exposure has been associated with eye cataracts, cancer induction (brain, breast and skin cancers), leukemia / lymphoma, melanoma, gastrointestinal and bone cancers, and thyroid and parathyroid adenomas, among others.

[0007] SUMMARY

[0008] Certain aspects, embodiments, features and components are described below in connection with compositions that can be used to absorb X-rays generated over a wide voltage range of 50 kV-150 kV. The composition can provide a desired lead equivalence value over this range as desired.

[0009] In an aspect, a composition for protection against X-rays generated from X-ray tubes with voltages of 50kV to 150 kV comprises transition metal particles dispersed in a polymer matrix. The transition metal particles can be present at 70% by weight or more based on the weight of the composition. For example, the transition metal particles can be present at 75% by weight or more, or 80% by weight or more, or 85% by weight or more. The balance of the composition (so the weight percentage adds to 100 weight percent) typically comprises a polymer and other additives or materials that may be helpful in forming the composition into desired articles.BURLMED-7003WO

[0010] In certain embodiments, the polymer matrix is an elastomer comprising one or more of a polyolefin polymer, a polyolefin copolymer, polyvinyl, a polyurethane, natural rubber or synthetic rubber. In other embodiments, the composition provides a 0.25 mmPb lead equivalence value over a range of the X-rays generated from X-ray tubes with voltages of 50kV to 150 kV.

[0011] In some embodiments, the transition metal particles have sizes from about 0.01 micrometers to about 100 micrometers.

[0012] In other embodiments, the polymer matrix comprises an elastomeric polymer. In certain configurations, the polymer matrix can be flexible, rigid or semi-rigid. In general, flexible and semi-rigid materials can be desirable to permit articles including the compositions to bend or flex at least to some degree without breaking.

[0013] In certain embodiments, the transition metal particles comprise first transition metal particles and second transition metal particles that comprise a different transition metal than the first transition metal particles. Where two or more different transition metals are present in the form of particles, the different transition metal particles together can be present at 70% by weight or more based on the weight of the composition. For example, the different transition metal particles can be present together at 75% by weight or more, or together at 80% by weight or more, or together at 85% by weight or more.

[0014] In some configurations, the composition comprises another metal different than the transition metal particles. In other embodiments, the composition comprises a non-metal. For example, the non-metal may be carbon, boron, a boron compound or other materials. In certain embodiments, the non-metal material comprises graphene or carbon nanotubes.

[0015] In certain embodiments, the transition metal particles comprises first transition metal particles, second transition metal particles that comprise a different transition metal than the first transition metal particles, and third transition metal particles that comprise a different transition metal than the first transition metal particles and a different transition metal than the second transition metal particles. Where three or more different transition metals are present in the form of particles, the different transition metal particles together can be present at 70% by weight or more based on the weight of the composition. For example, the different transition metal particles can be present together at 75% by weight or more, or together at 80% by weight or more, or together at 85% by weight or more.

[0016] In some embodiments, the composition is lead free.

[0017] In other embodiments, the transition metal particles comprise lead.

[0018] In another aspect, a process comprises forming the compositions described herein into a sheet with an effective thickness to provide a lead equivalence value of at least 0.125 mmPb over a range of X-rays generated from X-ray tubes with voltages of 50kV to 150 kV.BURLMED-7003WO

[0019] In other embodiments, the effective thickness provides a lead equivalence value of at least 0.175mmPb over the range of X-rays generated from X-ray tubes with voltages of 50kV to 150 kV. In further embodiments, the effective thickness provides a lead equivalence value of at least 0.25 mmPb over the range of X-rays generated from X-ray tubes with voltages of 50kV to 150 kV. In some embodiments, the sheet is formed by extrusion or co-extrusion of the composition.

[0020] Additional features, aspects, embodiments and configurations are described below.

[0021] BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0022] Certain illustrative compositions are described below with reference to the accompanying figures in which:

[0023] FIG. 1 lists K-absorption edge values for several elements;

[0024] FIG. 2 is a graphical representation showing X-ray absorption over a certain X-ray energy range;

[0025] FIG. 3 is an illustration showing an attenuation protection material (ATM) including micrometer size metal particles;

[0026] FIG. 4 is an illustration showing an ATM including mixed nano- and micrometer size metal particles;

[0027] FIG. 5 is an illustration showing ATM including nanometer size metal particles;

[0028] FIG. 6 is a graph showing the tensile strength - elongation curves for 0.125 mmPb and 0.250 mmPb ATM-1 sheets;

[0029] FIG. 7 is a graph showing tensile strength - elongation curves for 0.250 mmPb ATM-3 sheet;

[0030] FIG. 8 is a graph showing tensile strength - elongation curves for 0.250 mmPb virgin and aged ATM-4 sheet;

[0031] FIG. 9 is a graph showing tensile strength - elongation curves for different ATM-6 sheet thicknesses;

[0032] FIG. 10 is a graph where the tensile curves for 0.125 mmPb ATM-6 sheets, where the specimens are cut along the extrusion direction (machine direction, MD) and perpendicular to the extrusion direction (transverse direction, TD) are shown;

[0033] FIG. 11 is a graph showing tensile strength - elongation curves for 0.250 mmPb virgin and aged ATM-6 sheet;

[0034] FIG. 12 is a graph comparing measured LEV levels of ATM-5 and several competing materials;BURLMED-7003WO

[0035] FIG. 13 is a graph comparing measured LEV levels of ATM-3 and several competing materials;

[0036] FIG. 14 is a graph showing tensile strength - elongation curves for ATM-5 and several competing materials;

[0037] FIG. 15 is an illustration of an apron that can include the compositions described herein;

[0038] FIG. 16 is an illustration of a vest that can include the compositions described herein;

[0039] FIG. 17 is an illustration of a skirt that can include the compositions described herein;

[0040] FIG. 18 is an illustration of a protective wrap that can include the compositions described herein;

[0041] FIG. 19 is an illustration of a protective body wrap that can include the compositions described herein;

[0042] FIG. 20 is an illustration of a cap that can include the compositions described herein;

[0043] FIG. 21 is an illustration of a protective sleeve that can include the compositions described herein; and

[0044] FIG. 22 is an illustration of a thyroid shield that can include the compositions described herein.

[0045] DETAILED DESCRIPTION

[0046] Various shielding articles to protect the patients, medical staff and industry operators who are exposed to or work around ionized radiation, such as X rays are described herein. While a variety of articles, viz. aprons, vests, skirts, sleeves, suits, gloves, caps, pads, drapes, shields, curtains, and so on, are present on the market, the actual radiation-shielding materials (material compositions) that they are made of may not completely protect the wearer from the ionized rays. Not only the actual X rays, but the scattered rays are also of a great danger to everyone involved and currently present the main source of occupational health hazard for medical personnel. Therefore, various aspects described herein relate to material compositions that effectively protect against a wide range of X ray energies, e.g. those X-rays generated using X-ray tube voltages from about 40 kV to about 150 kV. The present material compositions involve at least one transition metal in combination with other elements (metals and non-metals). Certain aspects, embodiments and examples described herein are related to lead-free compositions with improved X ray and gamma ray shielding properties over a broad range of X ray and gamma ray energies, from below 40 kV to about 150 kV and above, and methods of making such compositions. In some instances, the compositions can provide attenuation of at least 90% against X-rays generated from X-ray tubes operating under voltages from 50 kV to 150 kV.BURLMED-7003WO

[0047] In certain configurations, the materials including the disclosed compositions can be flexible, crack-resistant, tear-resistant, and abrasion-resistant materials and can be used to make protective garments and other protective elements with improved attenuating properties against primary and scatter X rays. Moreover, certain arrangements of protective articles have tunable surface properties, such as low friction, antimicrobial, superhydrophobic, repellent, self-cleaning and other properties.

[0048] Many medium and high-atomic number (Z) elements, such as lead (Pb), tin (Sn), copper (Cu), antimony (Sb), barium (Ba), tungsten (W), bismuth (Bi), cesium (Cs), and others, as well as their oxides, salts, alloys, complexes, and others, can be used as radiation-protective metals. The element atomic number (Z-number), the K-absorption edge (K-edge) and the density are among certain relevant parameters considered when choosing the radiation shielding elements, which are usually added in a rigid, semi-flexible, or flexible plastic composition. The K-absorption edge (K-edge) refers to an abrupt increase in the photoelectric absorption of photons, and it usually corresponds to the energy level just beyond the binding energy of the K-shell electrons of the absorbing atom. K-shell binding energies are specific to each element and usually increase with the atomic number Z of the element, so does its corresponding K-shell binding energy, and therefore, the greater the photon energy at which the K-edge occurs. K-absorption edges for several elements are listed in FIG. 1.

[0049] In certain embodiments, compositions comprising at least one transition metal are disclosed. The transition metal(s) is used alone, or in combination with other elements, e.g., dispersed in a polymer composition, to provide efficient and extended range of X rays and gamma rays protection. All transition metals provide protection to a certain extent, but the most preferrable metals in this compositions described herein are the following elements: Lanthanides (La, Ce, Nd, Sm, Eu, etc.), Zirconium (Zr), Niobium (Nb), Molybdenum (Mo), Hafnium (Hf), Tungsten (W), Tantalum (Ta), Yttrium (Y), Vanadium (V), Chromium (Cr), Copper (Cu), other metals, such as indium (In), Tin (Sn), Aluminum (Al), Zinc (Zn), Nickel (Ni), Cobalt (Co), Manganese (Mn), etc. Moreover, compounds and / or alloys containing two or more protective metals, viz. Tungsten carbide, Bismuth Tungstate, Barium Tungstate, Bismuth Tin alloy, Antimony Tin alloy, Indium Tin oxide and others, are disclosed. In other instances, compounds including at least three of the protective metals or four of the protective metals can also be used. In some embodiments, the transition metals are used as pure metals and in other embodiments are used as compounds, such as but not limited to oxides, borides, nitrides, sulfides, sulfates, carbonates, etc. Pure metals and / or compounds which can provide for an extended range of X rays and gamma rays protection are particularly desirable. As noted in more detail below, extended range of X rays refers to X-rays generated using voltages ranging from 50 kV to 150 kV. The compositionsBURLMED-7003WO described herein can absorb X-rays generated over this voltage range and can also simultaneously absorb scattered X-rays having energies lower than 50 kV. For example and as shown pictorially in FIG. 2, the compositions described herein generally provide a desired LEV lead equivalence value (LEV) over an X-ray energy generation range of 50 kV to 150 kV. Scattered X-rays with energies below 50 kV can also be absorbed. In some embodiments, the lead equivalence value (LEV) of the compositions described herein, expressed in mm Pb, can be above 0.225 over a range of 50 kV-150 kV generated X-ray energies. As noted above, the energy ranges referenced herein refer to the energies used to generate the X-rays. For example, X-ray tube voltages of 50 kV-150 kV can be applied to generate the X-rays. In other examples, the LEV can be above 0.23 or above 0.235 or above 0.240 over a range of 50 kV-150 kV X-ray energies. In practice, different articles often specify certain levels of LEV. For example, for certain applications to provide appropriate X ray protection, the material needs to provide a LEV level which meets or exceeds certain specifications. In an apron, for example, a front panel typically needs to be 0.35 mmPb to 0.50mmPb, the back panel can be 0.250 mmPb, etc. In many instances, however, these values may only be tested over a narrow range (90-150 kV) to be able to meet the desired level specifications. The tested materials may not provide acceptable LEV levels below 90 kV or absorb scattered radiation, which often has energies below 50 kV.

[0050] Different combinations of elements and / or their compounds with distinct K-absorption edges are used. Specific examples include but not limited to Mo+W, Mo+Ba+Bi, Cd+Bi, Mo+La+Bi, Cd+W, In+Bi, In+Sm+Bi, Cs+Bi, Mo+Ce+Bi, Sb+Pb, Sm+Bi, Zr+Sm+ Bi, Ce+Sm+W, etc. These combinations can be used along with a binder, polymeric materials or other materials to form a composite material that can provide the extended range of X rays and gamma rays protection. In particular embodiments, graphene, boron and / or boron compounds, carbon nanotubes (single-wall- and multi-wall-carbon nanotubes) are added to enhance the shielding properties of the radiation protective compositions. Due to their unique 2D and / or 3D structures, graphene, carbon nanotubes and borides facilitate uniform and sometimes ordered metal dispersion throughout the shielding material, and thus, efficient shielding. In certain examples, hexagonal Boron nitride, Boron carbide, Molybdenum boride, Lanthanum hexaboride, Zirconium boride, Hafnium boride, Tungsten boride, and others, are used due to their unique spatial organization and / or crystalline structure. In other examples, an expanded graphite or a nanoclay, both being materials with high specific surface area and porosity are used. The porous material is doped, impregnated, or filled with radiation protective metal particles by any method or process known in the art. Such doped, impregnated, or filled porous material is then laminated, coextruded, or added to an elastomer to make the final radiation protective sheet with well dispersed metal particles.BURLMED-7003WO

[0051] In some embodiments, the radiation shielding composition is made of metals with various particle size distributions including, but not limited to, those in the range 0.1-100 micrometers, and preferably from 0.1-10 micrometers. In another embodiment, the particles of one metal are in the range 0.01-1 micrometers, and those of the second metal are in the range 1-100 micrometers. In yet another embodiment, the composition contains more than two shielding metals, each with different particle size distributions, such as but not limited to 0.01-10 micrometers, 1-20 micrometers. In another embodiment, nanoparticles with sizes (on average) below 100 nm are used. The large surface-area-to-volume ratio enables the nanoparticles to absorb X ray photons better. In yet another embodiment, a mixture of micrometer- and nanometer-size particles dispersed in a polymeric matrix is used to design effective radiation shields. FIGS. 3, 4 and 5 pictorially represent different arrangements. The arrows with the largest body width represent incident X-rays. The medium-size body width arrows and small body width arrows represent scatter X-rays.

[0052] The exact metal loading in the compositions described herein can vary and typically high metal loading rates are desirable. For example, total metal loading by weight can exceed 70% by weight based on the total weight of the composition. In other embodiments, total metal loading by weight can exceed 75% by weight based on the total weight of the composition. In some embodiments, total metal loading by weight can exceed 80% by weight based on the total weight of the composition. In certain embodiments, total metal loading by weight can exceed 85% by weight based on the total weight of the composition. The balance of the materials can be a combination of polymer, additives, etc. as noted herein. Metal loading is typically referenced based on the amount of material present in a metal compound such as an oxide or other form. For example, the use of 85% samarium oxide in a composition can represent 85% metal loading.

[0053] In certain embodiments, the compositions described herein can include at least 70% by weight or at least 80% by weight metal(s) where one of the metals is samarium or a samarium compound such as samarium oxide. In other embodiments, the compositions described herein can include at least70% by weight or at least 80% by weight metal(s) where one of the metals is zirconium or a zirconium compound such as zirconium oxide. In some embodiments, the compositions described herein can include at least70% by weight or at least 80% by weight metal(s) where one of the metals is lead or a lead compound such as lead oxide. In certain embodiments, the compositions described herein can include at least 70% by weight or at least 80% by weight metal(s) where one of the metals is antimony or an antimony compound such as antimony oxide. In some embodiments, the compositions described herein can include at least 70% by weight or at least 80% by weight metal(s) where one of the metals is antimony or an antimony compound such as antimony oxide and another metal is lead or a lead compound suchBURLMED-7003WO as lead oxide. In other embodiments, the compositions described herein can include at least 70% by weight or at least 80% by weight metal(s) where one of the metals is samarium or a samarium compound such as samarium oxide and another metal is bismuth or a bismuth compound. In some embodiments, the compositions described herein can include at least 70% by weight or at least 80% by weight metal(s) where one of the metals is zirconium or a zirconium compound such as zirconium oxide and another metal is bismuth or a bismuth compound and another metal is samarium or a samarium compound such as samarium oxide. In certain embodiments, the compositions described herein can include at least 70% by weight or at least 80% by weight metal(s) where one of the metals is cerium or a cerium compound such as cerium oxide and another metal is tungsten or a tungsten compound and another metal is samarium or a samarium compound such as samarium oxide.

[0054] In certain embodiments, the compositions described herein can generally be mixed along with suitable other materials and then shaped or formed into desired articles. Molding, extrusion, film forming techniques or other production methods can be used as desired. In one example, as combination of pelletizing and extrusion can be performed. For example, a batch mixer can be pre-heated to about 90-140 °C. Polymeric materials (e.g., elastomer) and any additives (e.g., slip agent, antioxidant, colorant, extrusion agent, and some plasticizer) can be added to the pre-heated batch mixer. The mixture can be mixed under pressure until a melting temperature is reached, which may vary depending on the materials used. Typical melting temperatures range from 140-155 °C though lower and higher melting temperatures may exist depending on the materials selected. To the melted mixture, the metals and any remaining plasticizer can added in several loading steps, e.g., 2-5 or 2-4 or 2-3 loading steps. The metal filled elastomer can be mixed to homogeneity, under pressure, at batch temperatures of 120-155 °C after each loading step. After the addition of all metals and plasticizer, the heated batch can be pelletized at temperatures of 130-160 °C. The resulting pellets can be air-cooled to room temperature and used in subsequent forming operations.

[0055] In certain configurations, the pellets can be extruded using an extruder. Extrusion of the pellets can be performed using a single screw extruder comprising two or more barrel heating zones. For example, three, four or five barrel heating zones can be used. The extruder can also include a screen changer, an adaptor and a flat horizontal die and optionally other components as desired. The material can be extruded directly onto a sheeting line containing a chill roll, a pressure roll, a paper roll and a roll stand to wind the sheeted attenuating material. The produced product can then be used in combination with other layers, fabrics, etc. to produce a radiation shielding article with desired features.BURLMED-7003WO

[0056] Certain specific examples are described to illustrate some of the novel and inventive features of the compositions described herein.

[0057] Example 1 : Attenuation protection material ATM-1 / DTAA-1

[0058] ATM-1 pellets comprising Sm-particles as protective metal were made following the general procedure listed above for mixing and pelletizing. The following equipment was used: the mixer was a Kneader Machinery Type: KD35-100D; and the pelletizer was from Kneader Machinery Type: KD-PR-12The pellets’ composition is given in Table 1.Table 1. ATM-1 Pellet CompositionMaterial Wt %Samarium(III) Oxide 84.68%Engage (Elastomer) 8.62%Kemamide U (Slip Agent) 0.17%BNX (Antioxidant) 0.18%PDMS (Extrusion Agent) 0.14%Sunpar (Hydrocarbon oil) 6.21%

[0059] Afterwards, the pellets were extruded as sheet attenuating material with a density of 3.43 g / cm3. The extruder used was from Davis Standard Type: DS66514. X-ray attenuation was measured at the Bavarian State Office of Weights and Measures in Munich, Germany under both, modified broad beam geometry (BBG*), according to IEC 61331-1 :2014, and under narrow beam geometry (NBG) over a kV range of 50- 150 kV for sheets of different thicknesses and area weights (different lead-equivalencies, mmPb). The test results expressed in terms of mmPb are given in Tables 2 and 3.BURLMED-7003WO Table 2 BBG* test results for ATM-1 attenuation sheetsTable 3. NBG test results for ATM-1 attenuation sheets

[0060] Dog-bone shaped specimens were cut from the extruded sheets and tested for their tensile properties according to the ASTM standard. The tensile strength - elongation curves for 0.125 mmPb and 0.250 mmPb ATM-1 sheets (FIG. 6) represent a material with a great balance of strength, ductility and toughness, independent on the sheet thickness.BURLMED-7003WO

[0061] Example 2, Attenuation protection material ATM-2

[0062] ATM-2 pellets comprising Zr-particles as protective metal were made following the general procedure for mixing and pelletizing and using the equipment described in Example 1. The pellets’ composition is given in Table 4. Afterwards, the pellets were extruded as sheet attenuating material with a density of 3.02 g / cm3. X-ray attenuation was measured at Health Physics Northwest in Milwaukie Oregon under narrow beam geometry (NBG) according to ASTM test method F2547-18 over a kV range of 50-100 kV for several samples of different thicknesses and area weights. The results are shown in Table 5 in terms of mmPb.Table 4. ATM-2 Pellet CompositionMaterial Wt %Zirconium(IV) Oxide 84.67%Engage (Elastomer) 8.85%Kemamide U (Slip Agent) 0.13%BNX (Antioxidant) 0.18%PDMS (Extrusion Agent) 0.13%Sunpar (Hydrocarbon oil) 6.04%Table 5. NBG test results for ATM-2 attenuation sheet

[0063] Example 3, Attenuation protection material ATM-3

[0064] ATM-3 pellets comprising Pb-particles as protective metal were made following the general procedure for mixing and pelletizing and using the equipment described in Example 1. The pellets’ composition is given in Table 6. Afterwards, the pellets were extruded as sheetBURLMED-7003WO attenuating material with a density of 3.61 g / cm3. X-ray attenuation was measured at the Bavarian State Office of Weights and Measures in Munich, Germany under both, modified broad beam geometry (BBG*), according to IEC 61331-1 :2014, and under narrow beam geometry (NBG) over a kV range of 50-150 kV for sheets of different thicknesses and area weights (different lead-equivalencies, mmPb). The test results expressed in terms of mmPb are given in Tables 7 and 8.Table 6. ATM-3 Pellet CompositionMaterial Wt %Lead (Pb) Oxide 84.50%Engage (Elastomer) 9.42%Kemamide U (Slip Agent) 0.08%BNX (Anti oxidant) 0.13%PDMS (Extrusion Agent) 0.08%Sunpar (Hydrocarbon oil) 5.79%Table 7. BBG* test results for ATM-3 attenuation sheetBURLMED-7003WO Table 8. NBG test results for ATM-3 attenuation sheet

[0065] Dog-bone shaped specimens were cut from the extruded sheets and tested for their tensile properties according to the ASTM standard. The tensile strength - elongation curves for 0.250 mmPb ATM-3 sheet (FIG. 7) represent a material with a satisfactory balance of strength, ductility and toughness, appropriate for example to be used as X ray shielding curtain.

[0066] Example 4, Attenuation protection material ATM-4

[0067] ATM-4 pellets comprising Pb- and Sb-particles as protective metals were made following the general procedure for mixing and pelletizing and using the equipment described in Example 1. The pellets’ composition is given in Table 9. Afterwards, the pellets were extruded as sheet attenuating material with a density of 3.62 g / cm3. X-ray attenuation was measured at the Bavarian State Office of Weights and Measures in Munich, Germany under both, modified broad beam geometry (BBG*), according to IEC 61331-1 :2014, and under narrow beam geometry (NBG) over a kV range of 50-150 kV for sheets of different thicknesses and area weights (different lead-equivalencies, mmPb). The test results expressed in terms of mmPb are given in Tables 10 and 11.BURLMED-7003WO Table 9. ATM-4 Pellet CompositionMaterial Wt % Antimony 30.43% Lead Oxide 55.33% Engage (Elastomer) 7.38% Evatane 40-55 (Co-Polymer) 0.92% Kemamide U (Slip Agent) 0.23% BNX (Anti oxi dant) 0.14% Akroplast Blue 35% PE (Colorant) 0.32% PDMS (Extrusion Agent) 0.14% Sunpar (Hydrocarbon oil) 4.66% Uninap (Hydrocarbon oil) 0.46%Table 10. BBG* test results for ATM-4 attenuation sheetBURLMED-7003WO Table 11. NBG test results for ATM-4 attenuation sheetATM-4 - NBG - IEC 61331-1:2014Area 50 60 90 110 150Nominal Weight Kv Kv 70 Kv Kv Kv Kvg / 100 mm mm mm mm mm mmmm Pb cm2Pb Pb Pb Pb Pb Pb0.125 16.37 0.122 0.126 0.127 0.130 0.127 0.1210.167 21.84 0.165 0.171 0.174 0.175 0.169 0.1600.175 22.29 0.174 0.180 0.183 0.184 0.177 0.1670.250 31.54 0.250 0.256 0.261 0.260 0.248 0.2310.350 44.45 0.360 0.364 0.367 0.365 0.349 0.3210.500 63.06 0.518 0.516 0.512 0.513 0.490

[0068] The ATM-4 material was subjected to accelerated aging process for 5 days at 50 oC in air in convection oven. Dog-bone shaped specimens were cut from the extruded sheets (virgin and aged sheets) and tested for their tensile properties according to the ASTM standard. The tensile strength - elongation curves for 0.250 mmPb virgin and aged ATM-4 sheet (FIG. 8) represent a material with a satisfactory balance of strength, ductility and toughness, and excellent durability.

[0069] Example 5, Attenuation protection material ATM-5

[0070] ATM-5 pellets comprising Zr-, Sm- and Bi-particles as protective metals were made following the general procedure for mixing and pelletizing and using the equipment of Example 1. The pellets’ composition is given in Table 12. Afterwards, the pellets were extruded as sheet attenuating material with a density of 4.07 g / cm3. X-ray attenuation was measured at the Bavarian State Office of Weights and Measures in Munich, Germany under both, modified broad beam geometry (BBG*), according to IEC 61331-1:2014, and under narrow beam geometry (NBG) over a kV range of 50-150 kV for sheets of different thicknesses and area weights (different lead-equivalencies, mmPb). The test results expressed in terms of mmPb are given in Tables 13 and 14.BURLMED-7003WOTable 12. ATM-5 Pellet Composition Material Wt % Zirconium(IV) Oxide 8.75% Samarium(III) Oxide 14.01% Bismuth 64.78% Engage (Elastomer) 6.76% Kemamide U (Slip Agent) 0.07% BNX (Antioxidant) 0.11% Carbon Black 50% EVA(Colorant) 0.53% PDMS (Extrusion Agent) 0.14% Sunpar (Hydrocarbon oil) 4.87%Table 13. BBG* test results for ATM-5 attenuation sheetsBURLMED-7003WOTable 14. NBG test results for ATM-5 attenuation sheets

[0071] Example 6, Attenuation protection material ATM-6

[0072] ATM-6 pellets comprising Ce-, Sm- and W-particles as protective metal were made following the general procedure for mixing and pelletizing and using the equipment of Example 1. The pellets’ composition is given in Table 15. Afterwards, the pellets were extruded as sheet attenuating material with a density of 4.07 g / cm3. X-ray attenuation was measured at Health Physics Northwest in Milwaukie Oregon under narrow beam geometry (NBG) according to ASTM test method F2547-18 over a kV range of 50-100 kV for several samples of different thicknesses and area weights. The results are shown in Table 16 in terms of mmPb.Table 15. ATM-6 Pellet CompositionMaterial Kg Wt % Cerium(IV) Oxide 38.05 29.12% Samarium(III) Oxide 38.05 29.12% Tungsten 38.10 29.17% Engage (Elastomer) 9.24 7.07% Kemamide U (Slip Agent) 0.18 0.14% BNX (Antioxidant) 0.23 0.17% PDMS (Extrusion Agent) 0.18 0.14% Sunpar (Hydrocarbon oil) 6.61 5.06%BURLMED-7003WOTable 16. NBG test results for ATM-6 attenuation sheets

[0073] The ATM-6 material was subjected to accelerated aging process for 5 days at 50 °C in air in convection oven. Dog-bone shaped specimens were cut from the extruded sheets (virgin and aged sheets) and tested for their tensile properties according to the ASTM standard. The tensile strength - elongation curves for different ATM sheet thicknesses are given in FIG. 9, while the tensile curves for 0.125 mmPb ATM-6 sheets, where the specimens are cut along the extrusion direction (machine direction, MD) and perpendicular to the extrusion direction (transverse direction, TD) are given in FIG. 10. Regardless of the sheet thickness or the direction that the mechanical strength and flexibility are tested across the sheet, the AM-6 material showed uniform mechanical properties. The curves for 0.250 mmPb virgin and aged ATM-6 sheet (FIG. 11) represent a material with a satisfactory durability. The toughness of the material, calculated as the area under the tensile strength-elongation curve is approximately 1, 100 MJ / m3, indicating a tough material, which can be applied for personal protective garments.

[0074] Comparative Example 1

[0075] The ATM-5 composition was used to compare LEV values across a range of X-ray energies. The Competitor 1-5 materials all claimed to provide a LEV value of 0.25 mmPb. The materials were all measured under modified broad beam geometry (BBG*), according to IEC 61331-1 :2014, over a kV range of 50-150 kV. The results are shown in FIG. 12. As noted above,BURLMED-7003WO the ATM-5 material included Zirconium-Samarium-Bismuth. Competitor 1, 2 and 5 included bismuth-antimony. Competitor 3 included cerium. Competitor 4 includes cerium and antimony.

[0076] A comparison of the LEV’S over the 50 kV-150kV range shows the ATM-5 material was the only material which actually measured close to the 0.25 mmPb LEV level over the entire 50-150 keV range. The IEC standard allows for + / - 7% variance of the nominal claimed LEV, but the competitor LEV’s below 90 kV is below the allowed variance in most instances. It is notable that the ATM-5 is a lead-free material. These results were consistent with ATM-5 being able to absorb X-rays and scattered X-rays from 50 kV-150 kV.

[0077] Comparative Example 2

[0078] The ATM-3 composition (PbO containing) was used to compare LEV values across a range of X-ray energies. The Competitor 1 and 2 materials claimed to provide a LEV value of 0.25 mmPb. The materials were all measured under modified broad beam geometry (BBG*), according to IEC 61331-1:2014, over a kV range of 50-150 kV. The results are shown in FIG. 13. Competitors 1 and 2 included lead.

[0079] A comparison of the LEV’s over the 50 kV-150kV range shows the ATM-3 material was the only material which actually measured close to the 0.25 mmPb LEV level at less than 90 kV energies and was comparable to competitors 1 and 2 at energies above 90 kV. The IEC standard allows for + / - 7% variance of the nominal claimed LEV. These results were consistent with ATM-3 being able to absorb X-rays and scattered X-rays from 50 kV-150 kV.

[0080] Comparative Example 3

[0081] Various mechanical properties of the material of Comparative Example 1 were measured. The results are shown in FIG. 14 for tensile strength-elongation percent. Elongation at break was measured to be 4-5X higher than competitor products when measured in tensile mode with a stretching rate of 500 mm / minute. The ATM-5 material was also much tougher with tensile strength values being 2-3X higher. Toughness is generally the area under the tensile strengthelongation curve. ATM-5 also has a good balance of strength and ductility.

[0082] Example Articles

[0083] The compositions described herein can be used to produce articles with desired LEV levels. The articles can include an apron 1500 (FIG. 15), a vest 1600 (FIG. 16), a skirt 1700 (FIG.17), a protective wrap 1800 (FIG. 18), a body wrap 1900 (FIG. 19), a protective cap 2000 (FIG.20), a protective sleeve 2100 (FIG. 21) and a thyroid shield 2200 (FIG. 22).BURLMED-7003WO

[0084] When introducing elements of the aspects, embodiments and examples disclosed herein, the articles “a,” “an,” “the” and “said” are intended to mean that there are one or more of the elements. The terms "comprising,” “including” and “having” are intended to be open-ended and mean that there may be additional elements other than the listed elements. It will be recognized by the person of ordinary skill in the art, given the benefit of this disclosure, that various components of the examples can be interchanged or substituted with various components in other examples.

[0085] Although certain aspects, examples and embodiments have been described above, it will be recognized by the person of ordinary skill in the art, given the benefit of this disclosure, that additions, substitutions, modifications, and alterations of the disclosed illustrative aspects, examples and embodiments are possible.

Claims

BURLMED-7003WO CLAIMS1. A composition for protection against X-rays generated from X-ray tubes with voltages of 50kV to 150 kV, the composition comprising transition metal particles dispersed in a polymer matrix, wherein the transition metal particles are present at 70% by weight or more based on the weight of the composition.

2. The composition of claim 1, wherein the polymer matrix is an elastomer comprising one or more of a polyolefin polymer, a polyolefin copolymer, polyvinyl, a polyurethane, natural rubber or synthetic rubber.

3. The composition of claim 1, wherein the composition provides a 0.25 mmPb lead equivalence value over a range of the X-rays generated from X-ray tubes with voltages of 50kV to 150 kV.

4. The composition of claim 1, wherein the transition metal particles have sizes from about 0.01 micrometers to about 100 micrometers.

5. The composition of claim 1, wherein the polymer matrix comprises an elastomeric polymer.

6. The composition of claim 1, wherein the polymer matrix is rigid.

7. The composition of claim 1, wherein the polymer matrix comprises a semi-rigid polymer system.

8. The composition of claim 1 , wherein the transition metal particles comprise first transition metal particles and second transition metal particles that comprise a different transition metal than the first transition metal particles.

9. The composition of claim 1, wherein the composition comprises another metal different than the transition metal particles.

10. The composition of claim 1, wherein the composition comprises a non-metal.

11. The composition of claim 10, wherein the non-metal comprises boron or a boron compound.BURLMED-7003WO 12. The composition of claim 10, wherein the non-metal material comprises graphene.

13. The composition of claim 10, wherein the non-metal material comprises carbon nanotubes.

14. The composition of claim 1, wherein the transition metal particles comprise first transition metal particles, second transition metal particles that comprise a different transition metal than the first transition metal particles, and third transition metal particles that comprise a different transition metal than the first transition metal particles and a different transition metal than the second transition metal particles, and wherein the transition metal particles are present at 80% by weight or more based on the weight of the composition.

15. The composition of claim 1, wherein the composition is lead free.

16. The composition of claim 1, wherein the transition metal particles comprise lead.

17. A process comprising forming the composition of claim 1 into a sheet with an effective thickness to provide a lead equivalence value of at least 0.125 mmPb over a range of X-rays generated from X-ray tubes with voltages of 50kV to 150 kV.

18. The process of claim 17, wherein the sheet is formed with a thickness to provide a lead equivalence value of at least 0.175mmPb over the range of X-rays generated from X-ray tubes with voltages of 50kV to 150 kV.

19. The process of claim 17, wherein the sheet is formed with a thickness to provide a lead equivalence value of at least 0.25 mmPb over the range of X-rays generated from X-ray tubes with voltages of 50kV to 150 kV.

20. The process of claim 17, wherein the sheet is formed by extrusion or co-extrusion of the composition.

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