A high voltage insulator and radiation shield made of barium sulfate composite having a polymer matrix and barium sulfate therein. The device may be made by casting. By means of use of various combinations of barium sulfate, other radiologically resistant materials, polymers, and third components, the physical, radiological and electrical properties of the finished products may be tailored to achieve desired properties. In addition, the invention teaches that radiation shielding, insulators, and combined radiation shield/insulators may be fashioned from the composite. A wide range of production methods may be employed, including but not limited to liquid resin casting.
|
9. An electrical insulator for an ion source, the insulator comprising:
a generally annular body having a diameter of at least 6 inches;
the body having at least one vacuum sealing surface dimensioned and configured to provide a tight seal;
at least one alignment pin projecting from the vacuum sealing surface of the insulator;
at least one metal insert secured to the body;
the body made of a material comprising:
a. a polymer matrix and
b. barium sulfate within the polymer matrix in an approximate amount of at least 35% by volume.
0. 15. A high voltage insulating radiation enclosure comprising:
a first truncated cone section and a second truncated cone section;
the two truncated cone sections secured together at their respective bases by an overlap joint;
an interior space defined by the two truncated cone sections;
the first and second truncated cone sections having walls, the walls made of a material comprising:
a) a polymer matrix; and
b) barium sulfate within the polymer matrix in an approximate amount of at least 10% by volume;
a first emission port passing through at least one wall; and
a second electrical port passing through at least one wall.
0. 1. A high voltage insulating radiation enclosure comprising:
a first truncated cone section and a second truncated cone section;
the two truncated cone sections secured together at their respective bases by an overlap joint;
an interior space defined by the two truncated cones sections;
the first and second truncated cone sections having walls, the walls made of a material comprising:
a) a polymer matrix and
b) barium sulfate within the polymer matrix in an approximate amount of at least 10% by volume;
a first emission port passing through at least one wall;
a second electrical port passing through at least one walls.
0. 2. The high voltage insulating radiation enclosure of
0. 3. The high voltage insulating radiation enclosure of
0. 4. The high voltage insulating radiation enclosure of
0. 5. The high voltage insulating radiation enclosure of
0. 6. The high voltage insulating radiation enclosure of
c) a third material.
0. 7. The high voltage insulating radiation enclosure of
0. 8. The high voltage insulating radiation enclosure of
0. 10. The electrical insulator of claim 9, further comprising at least one element selected from alignment pins projecting from the vacuum sealing surface of the insulator, metal inserts secured to the body, and combinations thereof.
0. 11. The electrical insulator of claim 9, further comprising a third material selected from the group consisting of electrically insulating materials, binders, high density materials, and combinations thereof.
0. 12. The electrical insulator of claim 11, wherein the third material comprises at least one member selected from the group of tungsten, lead, platinum, gold, silver, tantalum, calcium carbonate, hydrated alumina, tabular alumina, silica, glass beads, glass fibers, magnesium oxide/sulfate, wollastonite, stainless steel fibers, copper, carbonyl iron, iron, molybdenum, nickel and combinations thereof.
0. 13. The electrical insulator of claim 9, wherein the polymer matrix comprises at least one member selected from the following group: epoxy, polyester, polyurethane, silicone rubber, bismaleimides, polyimides, vinylesters, urethane hybrids, polyurea elastomer, phenolics, cyanates, cellulose, flouro-polymer, ethylene inter-polymer alloy elastomer, ethylene vinyl acetate, nylon, polyetherimide, polyester elastomer, polyester sulfone, polyphenyl amide, polypropylene, polyvinylidene flouride, acrylic, homopolymers, acetates, copolymers, acrylonitrile-butadiene-styrene, flouropolymers, ionimers, polyamides, polyamide-imides, polyacrylates, polyether ketones, polyaryl-sulfones, polybenzimidazoles, polycarbonates, polybutylene, terephthalates, polyether sulfones, thermoplastic polyimides, thermoplastic polyurethanes, polyphenylene sulfides, polyethylene, polypropylene, polysulfones, polyvinylchlorides, stryrene acrylonitriles, polystyrenes, polyphenylene, ether blends, styrene maleic anhydrides, allyls, aminos, polyphenylene oxide, and combinations thereof.
0. 14. The electrical insulator of claim 9, wherein the polymer matrix comprises epoxy resin in an approximate amount between about 50% and about 70% by volume.
0. 16. The high voltage insulating radiation enclosure of claim 15, further comprising an X-ray tube disposed within the hollow body.
0. 17. The high voltage insulating radiation enclosure of claim 15, further comprising at least one oil port passing through at least one wall.
0. 18. The high voltage insulating radiation enclosure of claim 15, wherein the polymer matrix comprises at least one member selected from the following group: epoxy, polyester, polyurethane, silicone rubber, bismaleimides, polyimides, vinylesters, urethane hybrids, polyurea elastomer, phenolics, cyanates, cellulose, flouro-polymer, ethylene inter-polymer alloy elastomer, ethylene vinyl acetate, nylon, polyetherimide, polyester elastomer, polyester sulfone, polyphenyl amide, polypropylene, polyvinylidene flouride, acrylic, homopolymers, acetates, copolymers, acrlonitrile-butadiene-styrene, flouropolymers, ionimers, polyamides, polyamide-imides, polyacrylates, polyether ketones, polyaryl-sulfones, polybenzimidazoles, polycarbonates, polybutylene, terephthalates, polyether sulfones, thermoplastic polyimides, thermoplastic polyurethanes, polyphenylene sulfides, polyethylene, polypropylene, polysulfones, polyvinylchlorides, stryrene acrylonitriles, polystyrenes, polyphenylene, ether blends, styrene maleic anhydrides, allyls, aminos, polyphenylene oxide, and combinations thereof.
0. 19. The high voltage insulating radiation enclosure of claim 15, wherein the polymer matrix comprises epoxy resin is an approximate amount of 50% to 70% by volume.
0. 20. The high voltage insulating radiation enclosure of claim 15, further comprising:
c) a third material.
0. 21. The high voltage insulating radiation enclosure of claim 20, wherein the third material comprises at least one member selected from the following group: electrically insulating materials, binders, high density materials and combinations thereof.
0. 22. The high voltage insulating radiation enclosure of claim 20, wherein the third material comprises at least one member selected from the following group: tungsten, lead, platinum, gold, silver, tantalum, calcium carbonate, hydrated alumina, tabular alumina, silica, glass beads, glass fibers, magnesium oxide/sulfate, wollastonite, stainless steel fibers, copper, carbonyl iron, molybdenum, nickel and combinations thereof.
|
|||||||||||||||||||||||||||
The application is a continuation-in-part of U.S. utility patent application No. 10/850,931 filed May 22, 2004 now abandoned in the name of the same inventor, Stuart McCord, and entitled LEAD FREE BARIUM SULFATE COMPOSITE, and claims the priority and benefit of that earlier application and all related applications, the entire disclosures of which are incorporated herein by this reference.
This invention relates to generally to X-ray and Ion beam electrical insulators and particularly to polymer-metal-precursor composite insulators in which the metal-precursor component is barium sulfate.
X-ray and gamma ray sources are presently being used in a wide array of medical and industrial machinery, and the breadth of such use expands from year to year. device devices. The presently preferred embodiment and best mode presently contemplated of the invention teaches a high voltage electrical insulator for ion implanter machines and a high voltage insulator for X-ray tube enclosures, both made of a cast polymer-barium sulfate composite comprising a high density plastic matrix having barium sulfate materials within it as filler. It is not presently known to use such barium family compounds in amounts greater than 10% by volume, since the structures in which they are emplaced in prior art are flexible and radio-opaque, not cast insulators with radiation shielding properties.
Barium sulfate is a white, soluble and somewhat heavy compound normally used in paper manufacture. It is also administered prior to X-ray of patients, either as a liquid or for marking of items inserted into the patient: in either case, it's its radio-opaque properties are used for internal navigation and diagnosis of patient's patients after the relatively low radiation exposure of such patients.
By teaching the use of barium sulfate, the range of materials which may be used instead of the single metal lead is increased and thus the breadth of the properties which may be achieved is increased, another benefit of the invention. In particular, when compared to lead-composites:
The present invention may be manufactured by casting with thermosetting materials and/or thermoplastic materials. In general, higher filler loadings may be advantageously employed.
The polymers, plastics and resins which may be advantageously employed in the present invention are too numerous for a complete list, however, a partial and exemplary list includes epoxy, polyester, polyurethane, silicone rubber, bismaleimides, polyimides, vinylesters, urethane hybrids, polyurea elastomer, phenolics, cyanates, cellulose, flouro-polymer, ethylene inter-polymer alloy elastomer, ethylene vinyl acetate, nylon, polyetherimide, polyester elastomer, polyester sulfone, polyphenyl amide, polypropylene, polyvinylidene flouride, acrylic, homopolymers, acetates, copolymers, acrlonitrile-butadiene-stryene styrene, flouropolymers, ionimers, polyamides, polyamide-imides, polyacrylates, polyether ketones, polyaryl-sulfones, polybenzimidazoles, polycarbonates, polybutylene, terephthalates, polyether sulfones, thermoplastic polyimides, thermoplastic polyurethanes, polyphenylene sulfides, polyethylene, polypropylene, polysulfones, polyvinylchlorides, stryrene styrene acrylonitriles, polystyrenes, polyphenylene, ether blends, styrene maleic anhydrides, allyls, aminos, and polyphenylene oxide. Numerous variations and equivalents are possible.
The invention is not limited to a single matrix component and a single barium sulfate composite, on the contrary multiple components may be included, for example, copolymers may be used or other mixtures of matrix elements. As another example, in tailoring of the physical properties of the composition, a blend of more than one shielding compound (such as a blend of barium sulfate and tungsten, tungsten-precursor, lead compounds, etc.) may be used.
In addition, the invention supports addition to the mixture of secondary fillers, binders, fibers and other components. As examples, additional electrically insulating materials, strengthening materials, materials to provide a uniform composition or bind other components, and/or density increasing materials may be used. A more specific list of examples includes such materials as tungsten metal, calcium carbonate, hydrated alumina, tabular alumina, silica, glass beads, glass fibers, magnesium oxide, wollastonite, stainless steel fibers, copper, carbonyl iron, steel, iron, molybdenum, and/or nickel.
In addition, the composite material of the present invention is susceptible to a wide range of processing methods both for creation of the material and creation of items incorporating the material. In addition to casting, other techniques including molding, aggregation, machining, liquid resin casting, transfer molding, injection molding, compression molding, extrusion, pultrusion, centrifugal molding, calerending, filament winding, and other methods of handling are possible. Additionally, the composite of the invention may advantageously be worked with known equipment such as molds and machine tools, thus avoiding costs associated with re-equipping production facilities. Furthermore, since the material contains no lead, significant cost and time savings may be realized and burdensome regulations regarding lead may be properly avoided during these processes.
In theory, the material may be substituted for lead oxide shielding on a basis of approximately 3.5 to 1. Thus, for typical lead oxide shielding of 0.070 inches thickness, a replacement may be manufactured at a ratio of 3.5 to 1 in thickness. In the case of liquid resin casting, this increased thickness further allows easier molding.
A first formulation and embodiment of the invention was derived from barium sulfate, epoxy resin and hydrated alumina. The formulation comprised 57% by volume of an epoxy resin (438 Novolac/HHPA curative, a trademark and product of the Dow Corporation), 35% barium sulfate (catalog no. RS-22BS-35) and 8% hydrated alumina. 12 inch square plates of 0.25 inch thickness were vacuum cast and examined. Test panels were machined from the plates.
The test item was compared to an equivalent lead-epoxy plate with a 14% vol/vol percentage.
Despite being a barium compound, the material is non-toxic, thus despite expectations, it may be used in lead replacement roles without excessive environmental regulation.
The dielectric strength was equal to the 14% lead item (300 volts/mil in both cases), and the arc resistance was approximately double that of the lead test item. This is an important factor in calculating MTBF for items made with the materials, as one source of failures is failure under arc, leading to carbon paths on the surface. Since the carbon paths are conductive, the item is rendered quickly unusable and the equipment in which it is used (micro-chip production, for example) must be shut down, interrupting manufacturing, therapy, etc.
A second test item was produced, using a second formulation and embodiment of the invention derived from barium sulfate and epoxy resin. The formulation comprised 60% by volume of an epoxy resin (438 Novolac/HHPA curative, a trademark and product of the Dow Corporation) and 40% barium sulfate. 12 inch square plates of 0.25 inch thickness were vacuum cast and examined. Test panels were machined from the plates.
In summary of the test results, it can be seen that for applications requiring high resistivity and high arc resistance, barium sulfate composites may be advantageously used to achieve the desired properties. While the two tests both utilized epoxy resin, the present invention is not so limited, neither to the specific epoxy resin used nor to epoxy resin in general. Applicant reiterates that the examples presented are only examples: further development will produce numerous other materials with a wide range of characteristics, components, and methods of production.
Two examples of an application of the composite are presented below, that of a an ion implantation device source insulator, and a an high voltage insulating X-ray box, though the invention is not so limited.
It can also be seen that for applications requiring high shielding ability (such as X-ray source shielding in the medical field) the invention may be formulated to provide a shielding ability sufficient for lead replacement.
Without undue experimentation higher density formulations may be produced on demand by mixing additional secondary fillers into the composition. While use of lead would under some circumstances be self-defeating, lead, tungsten, platinum, gold, iridium, silver, tantalum, and similar materials may be used. Alternatively, the barium sulfate volumetric percentage may be increased by use of injection molding, compression molding or transfer molding as permitted by materials handling techniques. As demonstrated by the example using hydrated alumina, other properties such as electrical resistivity/conductivity, workability, ductility, density, and so on may also be adjusted by use of secondary fillers, binders, and other agents in the composition.
Thus it is apparent that a wide variety of products may be produced, as the characteristics of the barium sulfate composite of the present invention may be tailored depending upon the desired end characteristics. In addition, the environmental contamination engendered by the product is of a different order of magnitude than that produced by products containing lead.
An exemplary list of embodiments which may advantageously be produced using the material of the present invention includes X-ray tube insulators, apertures and enclosures, X-ray tube high-voltage insulators and enclosures, X-ray tube high voltage apertures, X-ray tube high voltage encapsulation devices, high voltage insulating radioactive shielding containers and other medical X-ray and gamma ray housings. Industrially, an exemplary list of embodiments in which the composition of the invention may advantageously be incorporated include ion source insulators for ion implantation machinery and other devices for insulating, isolating, directing or shielding any radiation producing device. As stated, these lists are exemplary only and embodiments of the invention may be utilized within the art field of radiation shielding in a broad range of equivalent ways.
In use, the device may be placed directly against the ion source and/or may be placed around the ion stream at later points, for example, after magnetic devices which may focus, re-direct or otherwise alter the ion beam, or in any other location in which radiation or electrical charges may need to be blocked. Vacuum sealing surfaces 10 may facilitate provision of a tight seal. Alignment pin 20, one of several possible, may be used to assure proper alignment, the number and arrangement of pins obviously allows proper alignment to be assured in as many degrees of freedom as must be restricted. Metallic inserts 30 allow attachment of the device to the overall structure of the ion implanter device, medical device, or other device to which it belongs. The inserts have internal threads (not shown) allowing easy bolting to the larger machine of which the invention will be a part or a retrofit. Such features may be produced by molding, inserts, machining, or other means suitable for use with polymer materials as are known in the art. One additional desirable quality is that these features may be created “on demand” as requested by end users of the item.
Surface convolutions 40 may be used to provide additional properties such as to increase surface distance/area in order to prevent electrical arcing, to locally increase shielding or insulation, fit with other components of the overall system and so on.
While the exemplary ion source insulator is quite simple, such devices may be complex, having a much greater depth, having a much greater thickness, having multiple grooves and ridges and so on. Items created using the composite of the present invention need not be annular nor even circular but may be any shape as required. The range of sizes in such insulators is quite broad: from 1 inch to 20 or more inches tall, diameters from 6 to 40 inches, wall thicknesses which might be from ½ inch thick up to 3 inches thick and weights anywhere from under 1 pound to over 500 pounds.
The material of the device may be a barium sulfate composite as discussed previously.
As another example,
The enclosure 102 shown in cross-sectional perspective in
Enclosure/box 102 has a number of features required to allow X-ray tube 104 to function properly. Enclosure 102 has thick walls 110 of the desired composite material: on a 3.5 to 1 replacement basis, the walls may be approximately 3.5 times as thick as a corresponding lead oxide product, but at reduced cost. Oil cooling port 120 and electrical port 130 allow oil and electrical connections to the interior of the box. Overlap joint 140 is designed to prevent radiation leakage from the joint during the case manufacture.
While the exemplary ion source insulator is quite simple, such devices may be complex, having a much greater depth, having a much greater thickness, having multiple grooves and ridges and so on. Items created using the composite of the present invention need not be annular nor even circular but may be any shape as required. The range of sizes in such insulators is quite large: from 1 inch to 20 or more inches tall, diameters from 6 to 40 inches, wall thicknesses which might be from ½ inch thick up to 3 inches thick and weights anywhere from under 1 pound to over 500 pounds.
High voltage insulating X-ray shielding enclosures are typically of an even wider range of shapes and sizes, cylinders, three dimensional conic sections, prisms, regular and irregular solids and composite shapes. A typical “box” might be irregular, 16 inches on a side and have a weight from 1 to 30 pounds. The thickness of the walls may be even greater than that of industrial ion source insulators.
In short, regardless of shape or size of the item to be made the present invention may be adapted to any radioactive/ion/gamma ray/x-ray shielding application without undue experimentation and without departing from the scope of the invention. Formulations other than those specifically provided may be employed without departing from the scope of the invention.
The method of the invention, a process for producing a high voltage insulator having radiation shielding properties, may have the following steps:
TABLE I
A)
mixing uncured liquid epoxy polymers with desired percentages of
powdered barium sulfate and powdered hydrated alumina.
B)
blending the mixture in high shear single blade vacuum mixers for
a first predetermined time.
C)
Pouring, injecting or vacuum casting the material in a mold having
a generally annular body cavity having a diameter of at least 6 inches,
the body cavity having at least one vacuum sealing surface.
D)
Placing the material into an autoclave.
E)
Curing the mold and material therein at a temperature in a range from
at least 70 degrees F. to 400 degrees F. for a period depending upon
the size, configuration and exact choice of materials, the time ranging
from at least two hours to 24 hours, at a pressure ranging from at
least 50 to 250 psi.
This is in contrast to methods of creating thin and flexible radiation barriers, which do not involve casting.
This disclosure is provided to allow practice of the invention by those skilled in the art without undue experimentation, including the best mode presently contemplated and the presently preferred embodiment. Nothing in this disclosure is to be taken to limit the scope of the invention, which is susceptible to numerous alterations, equivalents and substitutions without departing from the scope and spirit of the invention. The scope of the invention is to be understood from the appended claims.
| Patent | Priority | Assignee | Title |
| 11217354, | Oct 06 2020 | King Abdulaziz University | Polyester nanocomposites for protection from hazardous radiation used for medical applications |
| D703622, | Mar 23 2012 | Mitsubishi Electric Corporation | Shield for vacuum circuit breaker |
| Patent | Priority | Assignee | Title |
| 2118413, | |||
| 3328338, | |||
| 3473028, | |||
| 4157476, | Feb 03 1978 | GENDEX CORPORATION A DE CORP | Dental X-ray tube head |
| 4485838, | Feb 24 1983 | Toray Industries, Inc. | Methods for manufacturing lead fiber and radiation shielding material using the same |
| 4619963, | Feb 24 1983 | Toray Industries, Inc. | Radiation shielding composite sheet material |
| 4938233, | Aug 03 1987 | WORLDWIDE INNOVATIONS AND TECHNOLOGIES, INC | Radiation shield |
| 4957943, | Oct 14 1988 | Minnesota Mining and Manufacturing Company | Particle-filled microporous materials |
| 5190990, | Apr 27 1990 | ADA Foundation | Device and method for shielding healthy tissue during radiation therapy |
| 5360666, | Apr 27 1990 | ADA Foundation | Device and method for shielding healthy tissue during radiation therapy |
| 5443775, | May 08 1992 | Plasticolors, Inc. | Process for preparing pigmented thermoplastic polymer compositions and low shrinking thermosetting resin molding composition |
| 5548125, | Jul 16 1991 | Smith & Nephew PLC | Radiation protective glove |
| 5665808, | Jan 10 1995 | Low toxicity composite bullet and material therefor | |
| 5719352, | Apr 22 1993 | GAMEBORE CARTRIDGE COMPANY LIMITED | Low toxicity shot pellets |
| 5730664, | Oct 11 1996 | SRI Sports Limited | Solid golf ball |
| 6048379, | Jun 28 1996 | IDEAS TO MARKET, L P ; TEXAS RESEARCH INTERNATIONAL, INC | High density composite material |
| 6166390, | Jan 23 1995 | Battelle Energy Alliance, LLC | Radiation shielding composition |
| 6310355, | Feb 18 1999 | Worldwide Innovations and Technologies, Inc. | Lightweight radiation shield system |
| 6487273, | Nov 26 1999 | VAREX IMAGING CORPORATION | X-ray tube having an integral housing assembly |
| 6548570, | Nov 16 1999 | ARNTZ BETEILIGUNGS GMBH & CO KG | Method for manufacturing a radiation shielding material |
| 6644853, | Apr 05 2002 | Midmark Corporation | X-ray tube head with improved x-ray shielding and electrical insulation |
| 6674838, | Nov 08 2001 | Varian Medical Systems, Inc | X-ray tube having a unitary vacuum enclosure and housing |
| 6722665, | Feb 04 2002 | Novellus Systems, Inc. | MESC seal, O-ring carrier |
| 6740260, | Mar 09 2002 | Resin Systems Corporation | Tungsten-precursor composite |
| 7079624, | Jan 26 2000 | VAREX IMAGING CORPORATION | X-Ray tube and method of manufacture |
| 7638783, | May 22 2004 | Resin Systems Corporation | Lead free barium sulfate electrical insulator and method of manufacture |
| 8022116, | Jul 18 2003 | Advanced Shielding Components, LLC | Lightweight rigid structural compositions with integral radiation shielding including lead-free structural compositions |
| 8263952, | Jun 22 2010 | Lead free barium sulfate electrical insulator and method of manufacture | |
| 8308986, | May 22 2004 | Bismuth compounds composite | |
| 20030168637, |
| Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
| Date | Maintenance Fee Events |
| Mar 15 2013 | M2551: Payment of Maintenance Fee, 4th Yr, Small Entity. |
| May 05 2017 | M2552: Payment of Maintenance Fee, 8th Yr, Small Entity. |
| Apr 16 2021 | M2553: Payment of Maintenance Fee, 12th Yr, Small Entity. |
| Date | Maintenance Schedule |
| Mar 05 2016 | 4 years fee payment window open |
| Sep 05 2016 | 6 months grace period start (w surcharge) |
| Mar 05 2017 | patent expiry (for year 4) |
| Mar 05 2019 | 2 years to revive unintentionally abandoned end. (for year 4) |
| Mar 05 2020 | 8 years fee payment window open |
| Sep 05 2020 | 6 months grace period start (w surcharge) |
| Mar 05 2021 | patent expiry (for year 8) |
| Mar 05 2023 | 2 years to revive unintentionally abandoned end. (for year 8) |
| Mar 05 2024 | 12 years fee payment window open |
| Sep 05 2024 | 6 months grace period start (w surcharge) |
| Mar 05 2025 | patent expiry (for year 12) |
| Mar 05 2027 | 2 years to revive unintentionally abandoned end. (for year 12) |