Polymer and elastomer compositions having carbon nanostructure additives and articles formed therefrom for use in EMI and rfi shielding and in pressure sensing seals having quantum tunneling composite effects

Abstract

This invention discloses a composition of at least one matrix polymer for forming articles and a method for manufacturing such articles. The matrix polymer may be a thermoplastic polymer and / or a curable polymer having at least one functional group for crosslinking. The composition and method include three-dimensional, branched, and crosslinked carbon nanostructure additives. The resulting articles may, in one specific example, provide a volume resistivity level of about 0.5 ohm-cm or less, and are suitable for applications requiring sufficient conductivity to provide electromagnetic interference shielding and / or radio frequency interference shielding. Other articles formed using the compositions disclosed herein may exhibit dissipative and / or quantum tunneling effects and are therefore suitable for use as self-sensing pressure-sensitive articles, such as self-sensing seals.

Description

Technical Field

[0001] Cross-reference to related applications

[0002] This U.S. non-provisional patent application claims the benefits of U.S. Provisional Patent Application No. 63 / 122,911, filed December 8, 2020, entitled “Polymer and elastomer compositions having carbon nanostructure additives and articles formed therefrom for EMI and RFI shielding and pressure-sensing seals having quantum tunneling effects,” under 35 USC §119(e), the entire disclosure of which is incorporated herein by reference.

[0003] This invention relates to the field of beneficial polymer and elastomer compositions, including those formed from curable fluorinated and perfluorinated compositions, and finished products derived therefrom, which incorporate carbon nanostructures of varying levels to enable the creation of articles, such as seals and gaskets, to provide unique electromagnetic shielding properties, especially under high loads, without significant micronization, and further allows for the formation of "smart" articles using these materials to instantly assess the performance of the articles when used in various end applications, particularly in semiconductor applications, by monitoring the conductivity of the material based on its volume resistivity over time. Prior Technology

[0004] Conductive polymers and elastomers are known, whether including intrinsically conductive polymers such as polyaniline, or prepared using conductive metals or carbon powder and / or particulate fillers and / or fiber fillers, and can include metals, polymers, carbon, graphite, and similar materials. Such polymers and elastomers are known for their use in shielding seals, gaskets, and other components against radio frequency interference (RFI) and / or electromagnetic interference (EMI) under high filler loads, preventing damage attributable to interference signals. They are also known in varying amounts for dissipative applications, such as in vehicle exterior components, where it is important to avoid ignition and fire risks by allowing electrostatic charges to flow from certain polymers to the ground. While polymer and elastomer compositions with conductive or dissipative properties are used in a variety of applications, there is still a need in this field to refine these materials for various end applications and for new and important end applications, such as the use of such materials in cleanroom environments. Furthermore, new areas and uses for such compositions remain to be developed.

[0005] Various components and assemblies used in manufacturing, particularly those for semiconductor manufacturing, including slit valves and gate valves, as well as other seals and gaskets, are well known. Regarding slit valves and gate valves, these gates close by abutting a seal or gasket against a surface within a semiconductor manufacturing apparatus to ensure that contaminants remain outside the reaction chamber and that reactants from within the chamber do not escape. However, such reaction chambers need to be opened and closed during manufacturing to allow wafers and similar target substrates used to manufacture wafers to move into and out of the reaction chamber. In a preferred design, the seals for such slit and gate valves are incorporated into a bonded assembly called a bonded slit valve (“BSV”). The goal in these cases is to minimize the level of microparticle formation, as microparticle formation can cause contamination during the process. In some cases, particles can be released as the seal deteriorates, and the final seal properties often tend to corrode over time. Therefore, measuring the reliability of the seals and minimizing microparticle formation are highly desirable characteristics in most semiconductor manufacturing applications.

[0006] Measuring the reliability and degradation rate of seals and gaskets is also a desirable end goal in a wide range of end applications, in order to maximize the effective production life of seals or gaskets while minimizing the final effects of leakage or impaired sealing properties caused by degradation.

[0007] BSV and other seals can be affected by different reactants and different reactant conditions. Such slit valves, which combine a door and a seal, operate on a valve actuated to open and close a door above the "slit" leading to a chamber. The seal is configured to seal around an opening or slit in the chamber and to seal the chamber opening when the valve is in the closed position. When the valve is open, a substrate used for semiconductor manufacturing moves into and out of the processing chamber through the slit.

[0008] Calibratory precursors, plasma, high temperatures, and other conditions can cause different types of seals to wear at variable rates. Most of these reaction chambers operate under vacuum conditions and use seals throughout the system to maintain the vacuum environment.

[0009] These seals are typically made from high-cost, chemically resistant elastomers, so it's understandable that we might not want to replace them until replacement is indicated. However, due to the variability in the effects of reactants and conditions on the various elastomers used to manufacture the seals, it is not always easy to predict when a seal will be damaged and / or when it will experience impending failure. The elastic sealing properties and other physical characteristics of the material can be tested to estimate failure in different environments and to provide information for predicting the seal's lifespan. However, for safety, given varying environments, conditions, and usage expectations, it is anticipated that seals will be replaced before damage, inconsistent product results, or specific product failures occur.

[0010] Because products manufactured in such environments are inherently very expensive, unnecessary maintenance downtime and / or failure costs can be even higher for manufacturers compared to replacing seals. Therefore, effective seal life is a key factor affecting chamber uptime, chamber usage, maintenance scheduling, and product nonconformity due to seal material degradation. Chemical, temperature, and other process conditions affect seal and door materials, as well as mechanical stresses resulting from valve actuation, all of which can cause seal degradation and failure.

[0011] Such issues also arise in other industries where maintenance costs, sealing costs, or downtime are high, and / or sealing functionality is critical to operational safety, making seal life monitoring and timely replacement at low cost important. In areas where particulate matter is a problem, such as in the semiconductor or pharmaceutical industries and other manufacturing cleanroom environments, minimizing such contamination is also crucial.

[0012] One way to address the anticipated lifespan of seals in the prior art is through testing, which can incur additional costs and / or labor. Monitors are sometimes also located within reaction chambers, which are monitored to modify conditions within the chambers that can affect manufacturing. Reactants are also monitored. Deterioration is typically detected by detecting vacuum leaks or the presence of particles generated from deteriorated seal material.

[0013] However, if there is a successful way to know when seals are damaged and / or affect the process and require maintenance, these problems can be improved, resulting in cost savings and minimizing failures. Furthermore, if there is a way to maximize seal life while avoiding the disadvantages of seal degradation mentioned above, operations can be improved.

[0014] In downhole applications in oilfield areas, feedback-providing seals are described in prior art, such as in U.S. Patent Publication No. 2017 / 0130562 A1, which teaches seals in demonstration wells and other components of wellhead assemblies that embed sensors within the seals to obtain data that can be used to determine and monitor the condition of the seals by monitoring physical operating conditions and stress or strain on the seals. This data is used to determine, on a scheduling basis, when the seals will need to be replaced, regardless of their condition. Data analyzers and predictive algorithms are used to compare the collected data with baseline data to evaluate the expected performance characteristics of the seals. Antennas and RFID tags or wear sensors may also be included. Sensors may also be embedded in the package.

[0015] Other prior art attempts have focused on monitoring the state of seal life or employing sensors and other detectors in semiconductor processing steps, including, for example, placing sensors on slit valves and sealing plates to monitor process status. However, such attempts are more typically focused on monitoring gate function, gate pressure, or preventing damage to process substrates moving in and out of the gate to ensure proper delivery and positioning within the chamber. This type of patent embeds or incorporates sensors in or on the seal, or separates them between chambers and / or between the inside and outside of chambers or gates to monitor pressure differentials.

[0016] U.S. Patent No. 7,841,582 B2 describes a method and apparatus for using an actuator to control the pressure on a slit valve to apply a different pressure to the actuator and the valve during cleaning compared to the reaction period, wherein the internal pressure during the reaction period will be higher than that during the cleaning period, so that the seal is not unnecessarily under high vacuum conditions during the cleaning period.

[0017] U.S. Patent No. 8,815,616 describes a slit valve unit having a housing surrounding the slit valve and a series of filling units (O-ring seals) to make the area airtight. The airtight area between the small conduit and the seals is in communication with a sensor unit that can monitor pressure changes to avoid explosions or leaks of the processed gas, and a control unit that can shut off to prevent events.

[0018] U.S. Patent No. 9,347,495 includes a bearing assembly formed using RFID, which has an inlet IC chip, an antenna connected to the chip, and a magnetic sheet function embedded in the bearing seal or raceway ring.

[0019] U.S. Patent No. 8,282,013 describes an embedded RFID transponder centered within a seal and subsequently vulcanized. The seal is therefore described as being capable of communicating via an RFID converter, which can be programmed to include information about the seal (part number, serial number, batch and / or lot number, code, size, manufacturing or sale date, installation and / or expiration date).

[0020] U.S. Patent No. 7,398,692 relates to a circuit chip attached in a coupled manner to an O-ring seal having an information transmission member for transmitting information to the outside of the sealing ring. The chip is sandwiched in a cutout within the seal body, and the cutout is then secured. Wiring attached to a sensor is pulled out from the body portion and connected to a pressure measuring device. Pressure monitoring is evaluated to measure internal seal stress, and the device automatically pulls away from the seal when the internal stress is reduced to 80%.

[0021] U.S. Patent Publication No. 2018 / 0052104 A1 describes the use of a wear indicator material for components that can be placed in various locations within a cavity. The wear indicator has different layers and a phosphorescent material that indicates wear.

[0022] U.S. Patent No. 9,975,758 includes microsensors that can be mounted on wafer processing equipment to monitor various conditions in real time. Microsensors can also be placed throughout the processing chamber and on tools.

[0023] U.S. Patent No. 7,658,200 B2 discloses the use of a pressure regulation system for two chambers separated by a slit valve. The purpose is to monitor the pressure difference within the chambers to prevent accidental opening. The patent teaches the use of pressure sensors in each chamber connected to a controller to prevent accidental opening. These sensors are not used to monitor conditions affecting the effectiveness of the seal.

[0024] U.S. Patent No. 6,575,186 describes the use of a series of sensors on a slit valve to control the rate of air pressure on the door, allowing for a softer landing during the closing process and preventing damage to the seals. Three sensors are used for positioning and interaction with the pneumatic closing system.

[0025] U.S. Patent No. 6,291,814 places a sensor at either end of a slit valve, which includes a transmitter and a receiver that monitor movement near the door to prevent damage to a moving wafer on a sealing plate.

[0026] U.S. Patent 5,363,872 describes a slit valve controlled based on a pressure differential on a barrier (described as a wall) between an inlet chamber and a reaction chamber. Each chamber has a sensor, and the pressure differential is analyzed to control the operation of the valve and the pressure applied by the slit valve.

[0027] The applicant in this paper has contributed to the development of products for monitoring the characteristics in reaction chambers. Previously, a camera known as a "wafer camera" that allows for camera sensing of the interior of the processing chamber has been developed. However, this camera was not developed for monitoring the performance of seals in BSV or other semiconductor valve assemblies.

[0028] Attempts have been made to form objects that utilize quantum tunneling for quantum tunneling purposes, using needle-like particles and / or pressure-sensitive particles for conductivity, such as nickel-graphite coated with silicone in a thin sheet, composite structures of needle-like particles and dielectric particles in a liquid silicone matrix that can be used as a converter, and pressure-sensitive conductive fabrics, as described in U.S. Patent Nos. 6,646,540, 6,495,069, 7,301,435, 8,449,974, 8,765,027, and 9,546,859. The same inventor also describes polymeric or elastomeric adhesives, such as polyurethane, natural rubber, polyvinyl acetate, polyvinyl chloride, acrylic polymers, and silicone, including structures with voids, such as the combination of spiked nickel and spherical magnetic conductive materials used in the aforementioned patents. The final material description includes a force sensor capable of providing switching (field-assisted tunneling) and sensing (conductive tunneling), formed in a device in thin films, sheets, filaments, filament coatings, 3D printing raw materials, and textiles.

[0029] The applicants had previously co-developed the intelligent seal described in U.S. Patent Publication 2020-0378867-A1, which is based on the use of sensors located at various positions on the BSV. These sensors read data related to micro-stress / micro-strain, stress relaxation, micro-strain measured against vacuum pressure acting on the door, temperature assessed for the seal's cross-sectional geometry, and the effect of temperature on micro-strain. This data is compared with adjusted baseline data to determine the seal's lifespan in real time.

[0030] Such attempts at measurement characteristics are highly applicable; however, it would be advantageous in this technology to provide simpler or different effects as an alternative for indicating seal life without the need for extensive use of sensors to provide the required data, especially since such sensors have no significant impact on the seal’s ability to function above the seal and maintain consistent characteristics without the use of embedded microsensors or other sensor devices attached to the seal.

[0031] This technology still requires improved methods to ensure maximum applicable seal life and importance analysis, which will help select the best seals for semiconductor processing and the relevant maximum seal life, so as to minimize downtime and uptime, improve maintenance cycles and avoid seal deterioration failures. This is easy to monitor and better does not affect the operation of the seal or the consistency of its characteristics, including maintaining good seal elasticity, mechanical and chemical resistance properties.

[0032] This technology further necessitates seals suitable for semiconductor manufacturing processes and / or cleanroom environments, providing diverse and / or reactive electrical properties while remaining cleanroom-friendly, eliminating the need for coarse metal fillers even in the event of seal degradation over time. Furthermore, to provide controlled but varying levels of electrical properties for specific end applications (such as electronic shielding or dissipation applications), such clean seals with consistent conductivity levels throughout the seal and within a low to high conductivity range are further required. Such materials will be particularly suitable for semiconductor end applications requiring low levels of micronization and contamination.

[0033] In this technology, gaskets and seals can be used for EMI shielding and / or RFI shielding in various end applications. For example, a shield can be inserted between an electromagnetic radiation source and the area to be protected. Shielding devices may include shielding gaskets or seals and can appear in various configurations to close the gap between the EMI shielding device and the area to be protected. EMI shielding devices may include multiple layers and / or coatings that can be applied to various materials by sputtering conductive materials onto the surface of those materials using metals such as nickel or tin. Various matrix materials have been used for such components and assemblies, including metals and polymeric or elastomeric materials such as silicone, fluorosilicone, ethylene-propylene copolymers, epoxy polymers, and polyurethanes. Typically, the fillers used in such materials are inherently conductive, generally including metals or carbon, and are in the form of particulate or fibrous fillers. For example, Russian Patent Publication No. RU2724650 C1 discloses the use of spherical particles of aluminum, graphite, or copper in silicone, fluorosilicone, or ethylene-propylene copolymers.

[0034] U.S. Patent Application Publication No. 2012 / 0177906 A1 teaches an EMI shielding composite material having a volume resistivity of not more than 0.5 ohm-cm, the material having a metallic filler dispersed in a thermoplastic matrix. The thermoplastics used include polyethylene, polyketone, and thermoplastic fluoropolymers (such as Teflon FEP or polytetrafluoroethylene). The metallic filler may be nickel particles or powder, silver-coated tin, or fiber fillers such as stainless steel, bronze fibers, aluminum fibers, or nickel fibers. The patent describes a filler load of up to 70% by weight.

[0035] Conductive elastomers can also be used for EMI shielding. For example, U.S. Patent No. 9,814,164 discloses EMI shielding in a sealing system incorporating conductive elastomers such as conductive silicone rubber. It further describes the use of silicone rubber or fluorosilicone rubber with embedded silver-plated aluminum particles, silver-plated glass beads, silver-plated copper particles, nickel-graphite particles, or conductive carbon.

[0036] U.S. Patent No. 8,633,402 describes EMI gaskets that can be formed from elastomeric polymers such as resilient polyethylene, polypropylene, polypropylene-EPDM blends, butadiene, styrene-butadiene, nitrile rubber, chlorosulfonate, chloroprene rubber, silicone, ethyl carbamate, and fluorosilicone. The polymer may be filled with conductive particulate fillers such as carbon, graphite, copper, nickel, silver, and aluminum.

[0037] U.S. Patent No. 7,589,284 describes an EMI shielding material that may include an elastomeric matrix, such as silicone, ethyl carbamate, or a flexible epoxy resin; a non-conductive thermoplastic material, such as polystyrene, polycarbonate / acrylonitrile-butadiene-styrene blend, polybutylene terephthalate, nylon, polycarbonate, polyacrylonitrile-butadiene-styrene; or a conductive polymer, such as polyaniline. The matrix material includes conductive fillers, such as nickel-plated carbon powder, carbon powder, silver powder, copper powder, silver / copper powder, silver / aluminum powder, silver-plated glass beads, or nickel powder.

[0038] U.S. Patent No. 9,635,790 describes a mesh sealing element, which is a conductive sheet embedded in a matrix polymer gel that may include an expanded metal.

[0039] U.S. Patent Application Publication No. 2003 / 0213939 describes thermoplastic or thermosetting elastomers, such as polyurethane, styrene-butadiene rubber, EPDM, and ethylene-propylene rubber, and other thermoplastic or thermosetting elastomers filled with carbon nanotubes and having a volume resistivity of 0.01 ohm-cm to 10⁸ ohm-cm. The carbon nanotubes include vapor-grown nanotubes, which can be multi-walled or single-walled. Carbon nanofibers may also be used. Metal fillers, such as carbon black and metal-coated fibers, may also be used.

[0040] Shielding materials commonly used in semiconductor or cleanroom applications typically employ nickel-coated graphite particles within silicone polymers. While a variety of EMI and RFI composites are available, not all are satisfactory when used in cleanroom seals or environments such as semiconductor manufacturing processes. These environments may require higher purity sealing materials (e.g., melt-processable fluoropolymers or perfluoropolymers, fluoroelastomers or perfluoroelastomers) or other polymers that do not introduce contaminants into the manufacturing process. To achieve the desired electrical properties, in most cases, the conductive filler load must be quite high to even achieve the nominal EMI and / or RFI shielding effect, and extremely high to achieve high efficiency levels. Such high filler loads are not possible for certain “clean” or highly chemically resistant matrices when maintaining adequate sealing and physical properties is also desired. Furthermore, in cleanroom environments, many current state-of-the-art EMI and / or RFI filler materials (such as nickel-coated graphite or metal fillers) can become problematic particles as the seal deteriorates over time. For some known EMI and / or RFI shielding materials in this technology, it may be difficult to maintain consistent properties throughout the entire matrix material of the composition. Therefore, conductivity may also be inconsistent within the matrix, resulting in excessive differences in performance and characteristics.

[0041] Developing EMI and / or RFI shielding components for use in the manufacture of seals would be beneficial, as these seals provide good sealing and physical properties, effective EMI and / or RFI shielding, and preferably also minimize any impact on conductive materials in clean environments when the underlying matrix deteriorates.

[0042] Therefore, this technology further requires the development of components that can provide controlled levels of electrical properties when required for specific end applications, whether for forming self-sensing materials with conductive and dissipative properties as described above, for providing EMI and / or RFI shielding materials, or for other conductive end uses. This technology further requires materials with generally consistent conductivity levels throughout the seal, gasket, or other shielding assembly, and within a low to high conductivity range. Such materials are particularly suitable for semiconductor end applications requiring low levels of micronization and contamination. Summary of the Invention

[0043] This invention includes novel compositions and articles formed therefrom, which can be used in a variety of end applications, including for use in higher conductivity end applications for EMI shielding and / or RFI shielding, or for lower conductivity or dissipative end applications in which the articles can exhibit conductivity as thermoplastic or elastic quantum tunneling composites (QTCs), such that the articles exhibit conductivity when subjected to compressive stress (e.g., under load) is higher than the article exhibits conductivity when the compressive stress is released. In one specific example, it can be insulating and then exhibit conductivity when stress is applied. The measured change in conductivity of the article (whether initially insulating or conductive) without compressive stress and its increased conductivity when subjected to compressive stress can be used to measure the lifetime of articles such as seals or gaskets over time. The composition can also be inherently dissipative.

[0044] This paper reveals various specific examples in which the components can be used to form articles suitable for end applications of electromagnetic interference or radio frequency interference.

[0045] In one such specific example, a composition for forming an article is disclosed, comprising at least one matrix polymer selected from the group consisting of: at least one thermoplastic polymer and / or at least one curable polymer having at least one functional group for crosslinking; and a three-dimensional, branched and / or crosslinked carbon nanostructure additive provided in an amount such that, after forming an article with the composition, the article is conductive and has a volume resistivity level of about 0.5 ohm-cm or less.

[0046] When formed into an article, in the specific examples described herein, the article is an electromagnetic interference shielding article and / or a radio frequency interference shielding article.

[0047] In this specific example, the at least one matrix polymer may be at least one curable polymer selected from the group consisting of: a curable polymer containing at least one silicon-containing monomer, a curable polymer containing at least one silicon- and fluorine-containing monomer, a curable copolymer containing at least one acrylonitrile monomer and at least one butadiene monomer, a curable polymer containing at least one olefin monomer, a curable polymer containing at least one fluorinated monomer, a curable polymer containing at least one perfluorinated monomer, and blends and copolymers thereof. After curing, the cured polymer composition comprises one or more elastomers selected from the group consisting of: silicone, fluorosilicone, fluoroelastomer, perfluoropolyether, perfluoroelastomer, and cured elastomers formed from blends and copolymers thereof. In one specific example, the at least one curable polymer may be selected from the group consisting of: curable fluorinated polymers and curable perfluorinated polymers. The at least one curable polymer may further be at least one curable perfluorinated polymer or a blend or copolymer of at least one curable fluoropolymer and at least one curable perfluorinated polymer.

[0048] In one specific example, the matrix polymer is at least one curable polymer having at least one functional group for crosslinking, and the composition may further include at least one crosslinking additive for reacting with the at least one crosslinking functional group. After curing the curable polymer composition, the resulting cured material can be used for electromagnetic interference shielding applications or radio frequency interference shielding applications.

[0049] In one specific example in this article, the carbon nanostructure additive has a carbon content greater than or equal to (≥) about 97% and a bulk density of about 0.135 g / cm³.

[0050] The composition may further include at least one filler that is different from the at least one carbon nanostructure additive.

[0051] In this specific example, the composition may further include about 0.1 parts by weight to about 300 parts by weight of the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer, more preferably about 0.25 parts by weight to about 250 parts by weight of the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer, and most preferably about 0.5 parts by weight to about 250 parts by weight of the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer. In another specific example, the composition may include about 0.5 parts by weight to about 80 parts by weight of the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer.

[0052] In this specific example, when the at least one matrix polymer is selected from the group consisting of at least one curable fluoropolymer, at least one curable perfluoropolyether, and at least one curable perfluoropolymer, the composition may include about 10 to about 80 parts by weight of the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer, more preferably about 10 to about 50 parts by weight of the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer, and most preferably about 20 to about 40 parts by weight of the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer.

[0053] In another specific example of this composition, the matrix polymer may be a thermoplastic polymer selected from the group consisting of: polyaryl polymers, thermoplastic melt-processable fluoropolymers, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, chlorinated fluoropolymers, silicone polymers and non-curable fluoropolymers and perfluoropolymers, polyolefins, polyethylene terephthalate, polysiloxanes, polyurethanes, aromatic polyamines, polyamines, polyimides, polyetherimides, polyphenylene sulfide, polyphenylene oxide, polyether oxide, polyamideimide, polybenzimidazole, polycarbonate, polyacrylonitrile-butadiene-styrene, polybutadiene-styrene, polyepoxides and similar materials, as well as blends, copolymers, admixtures and other combinations thereof.

[0054] The composition may further include one or more conductive fillers different from the carbon nanostructure additive, such conductive fillers being selected from the group consisting of powder, flake, and fiber fillers, comprising one or more of the following: carbon, metallized glass, metallized particles comprising metal or polymer, nickel-coated graphite, graphene, graphite, carbon black, graphene derivatives, single-walled carbon nanotubes, multi-walled carbon nanotubes, gold, silver, nickel, copper, and combinations or mixtures thereof. In such specific examples, the composition may contain about 0.25 parts by weight to about 100 parts by weight of the conductive filler different from the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer.

[0055] When the aforementioned composition is formed from the matrix polymer, the present invention further includes articles formed from the composition. These articles may be selected from gaskets, seals, covers, and component portions, and are intended for use in electromagnetic interference shielding devices or radio frequency interference devices.

[0056] The present invention further includes an electromagnetic interference shielding and / or radio frequency interference shielding composition comprising: at least one matrix polymer selected from thermoplastic polymers and / or curable polymers having at least one functional group for crosslinking, the curable polymer being selected from at least one curable fluoropolymer, at least one curable perfluoropolyether, at least one perfluoropolymer, at least one curable polymer comprising silicon and fluorine, and copolymers and blends thereof; and a carbon nanostructure additive comprising about 5 parts by weight to about 300 parts by weight per 100 parts by weight of the at least one matrix polymer, wherein when the composition is cured and formed into an article, it has a volume resistivity level of about 0.5 ohm-cm or less, and wherein the carbon nanostructure additive is three-dimensional, branched and crosslinked.

[0057] In this specific example of an electromagnetic interference shielding and / or radio frequency interference shielding composition, the at least one matrix polymer may be at least one curable perfluoropolymer, and the composition may include about 10 to about 80 parts by weight of the carbon nanostructure additive per 100 parts by weight of the at least one curable polymer. Furthermore, in this specific example, the at least one carbon nanostructure additive may have a carbon content of ≥97% and a bulk density of about 0.135 g / cm³.

[0058] The present invention further includes a composition comprising: at least one matrix polymer selected from thermoplastic polymers and / or curable polymers having at least one functional group for crosslinking; and a three-dimensional, branched, and / or crosslinked carbon nanostructure additive provided in an amount such that, after an article is formed from the composition, the article exhibits one or more of a dissipative effect and a quantum tunneling recombination effect. In this specific example, the composition may include about 1 to about 30 parts by weight, and more preferably about 15 parts by weight, of the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer.

[0059] In this specific example, when the article is formed from the composition, the article exhibits a quantum tunneling effect, and the composition preferably comprises at least about 2 parts by weight of the carbon nanostructure to about 30 parts by weight per 100 parts by weight of the at least one matrix polymer, and more preferably about 15 parts by weight of the additive, more preferably at least about 3 parts by weight of the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer, and most preferably at least about 4 parts by weight of the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer. In one specific example, the composition comprises about 4 parts by weight to about 20 parts by weight of the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer, and more preferably about 4 to about 15 parts by weight of the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer.

[0060] In this specific example, the matrix polymer may be a thermoplastic polymer selected from the group consisting of: polyaryl polymers, thermoplastic melt-processable fluoropolymers, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, chlorinated fluoropolymers, silicone polymers and non-curable fluoropolymers and perfluoropolymers, polyolefins, polyethylene terephthalate, polysiloxanes, polyurethanes, aromatic polyamines, polyamines, polyimides, polyetherimides, polyphenylene sulfide, polyphenylene oxide, polyether oxide, polyamideimide, polybenzimidazole, polycarbonate, polyacrylonitrile-butadiene-styrene, polybutadiene-styrene, polyepoxides and similar materials, as well as blends, copolymers, admixtures and other combinations thereof.

[0061] The composition may further comprise one or more conductive fillers different from the carbon nanostructure additive, such conductive fillers being selected from the group consisting of powder, flake, and fiber fillers, comprising one or more of the following: carbon, metallized glass, metallized particles comprising metal or polymer, nickel-coated graphite, graphene, graphite, carbon black, graphene derivatives, single-walled carbon nanotubes, multi-walled carbon nanotubes, gold, silver, nickel, copper, and combinations or mixtures thereof. In such specific examples, the composition comprises about 0.25 parts by weight to about 100 parts by weight of the conductive filler different from the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer.

[0062] The invention may further include articles formed from the composition according to this specific example. The articles may be thermoplastic and / or elastic quantum tunneling composites, and may optionally comprise a group of other components in a free seal, gasket, or sealing assembly.

[0063] In one specific instance, the article is an insulator when not under compressive stress, and is conductive when under compressive stress. In another specific instance, the article's conductivity level when not under compressive stress differs from its conductivity level when under compressive stress.

[0064] In another specific example, the article may be an elastic quantum tunneling composite and a self-sensing article, wherein when the article is electrically connected to a circuit and a voltage is applied, the change in conductivity of the article when the article is in use and subjected to compressive stress is measured, and the change in conductivity is used to determine and evaluate the performance of the article in real time.

[0065] The present invention further includes a method of manufacturing an article comprising providing a composition comprising at least one matrix polymer selected from thermoplastic polymers and / or curable polymers having at least one functional group for crosslinking, and the composition comprising at least one three-dimensional, branched and / or crosslinked carbon nanostructure additive, wherein the at least one carbon nanostructure additive is present in an amount of about 0.1 parts by weight to about 300 parts by weight per 100 parts by weight of the at least matrix polymer; and forming an article from the composition by thermoforming or by curing and thermoforming the composition, wherein the article can be used in at least one of electromagnetic shielding devices and radio frequency shielding devices.

[0066] In this method, the volume resistivity of the article is preferably about 0.5 ohm-cm or less. The at least one matrix polymer may be a curable polymer, and the composition may further include at least one crosslinking additive for reacting with the at least one crosslinking functional group. In this method, the article may be selected from seals, gaskets, covers, or component portions of electromagnetic interference shielding devices and / or radio frequency interference shielding devices.

[0067] The present invention also includes a method of manufacturing an article comprising providing a composition comprising at least one matrix polymer selected from thermoplastic polymers and / or curable polymers having at least one functional group for crosslinking, and the composition comprising at least one three-dimensional, branched, and crosslinked carbon nanostructure additive, wherein the at least one carbon nanostructure additive is present in an amount of at least about 1 part by weight to about 30 parts by weight per 100 parts by weight of the at least one matrix polymer; and forming an article from the composition by thermoforming or by curing and thermoforming the composition, wherein the article exhibits at least one of dissipative effect or quantum tunneling effect.

[0068] In this method, the article can be a seal, gasket, or other component in a sealing assembly. The matrix polymer can be a curable polymer, and the composition can contain at least one crosslinking additive for reacting with the at least one crosslinking functional group. The curable polymer can be selected from the group consisting of curable fluoropolymers, curable perfluoropolyethers, and curable perfluoropolymers, as well as blends and copolymers thereof. In one specific example, the article is an elastic quantum tunneling composite. In one specific example, the article is an insulator when not under compressive stress and is conductive when under compressive stress. In another specific example, the article is conductive when not under compressive stress and has a conductivity level different from that when the article is under compressive stress, and in one specific example, the conductivity level of the article under compressive stress is higher than that when the article is not under compressive stress.

[0069] In another specific example, the article is an elastic quantum tunneling composite and a self-sensing article, and when the article is electrically connected to a circuit and a voltage is applied, the change in conductivity of the article when the article is in use and subjected to compressive stress is measured, and the change in conductivity is used to determine and evaluate the performance of the article in real time. Simple Explanation of the Diagram

[0070] The foregoing description of the invention and the following preferred embodiments will be better understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the invention, preferred embodiments are shown in the drawings. However, it should be understood that the invention is not limited to the precise configurations and means shown. In these drawings:

[0071] [Figure 1] is a three-dimensional plot showing the particle size level of the sample tested in Example 1 of this paper over time;

[0072] [Figure 2] is a series of graphical representations of volume resistivity relative to the compression percentage of samples 12-16 in the O-ring form used in Example 2 of this paper;

[0073] [Figure 3] is a series of graphical representations of volume resistivity relative to the compression percentage applied to samples 17-20 of Example 2;

[0074] [Figure 4] is a series of graphical representations of the volume resistivity of samples 12-20 in the form of buttons in Example 2;

[0075] [Figure 5] is a circuit diagram used to measure the resistance in Example 3;

[0076] [Figure 6] is a graphical representation of the relationship between conductivity in Siemens units / cm and the percentage of compression applied to samples 29-31 of Example 3;

[0077] [Figure 7] is a graphical representation of the relationship between the conductivity and compression percentage of samples 37-40 in Example 3;

[0078] [Figure 8] is a graphical representation of the combined data from Figures 6 and 7 for samples 29-31 and 37-40 of Example 3; and

[0079] [Figure 9] shows an embodiment of a circuit used with a four-point probe configuration for monitoring changes in conductivity in a seal made according to the present invention. Implementation

[0080] As used herein, word combinations such as “inner” and “outer”, “up” and “down”, “near” and “far”, “top” and “bottom”, and word combinations with similar meanings are used in this document to assist the reader in better understanding the invention in light of the diagrams herein, and are intended to help the reader not to limit the invention in any way.

[0081] The applicant has developed compositions and methods using varying amounts of specific types of carbon nanostructure additives to provide articles with varying electrical conductivity, enabling them, for example, to be used as additives in EMI shielding and / or RFI shielding applications, or in amounts that allow the articles to function as quantum tunneling complexes (QTCs) or dissipative conductive polymers or elastomers for various end applications. When functioning as a QTC, in a specific instance, a seal or gasket can, for example, respond to a compression level that can be converted from changes in conductivity under compressive stress in use by the polymer or elastomer, thus allowing for immediate assessment of the seal or gasket's lifespan.

[0082] Therefore, for sealing applications, seals can be manufactured to act as self-sensing seals for use in a variety of end applications, where monitoring seal life is critical for efficient and low-cost sealing performance and maintenance. In semiconductor applications, such seals can be used in valve assemblies with seals, such as slit valves with seals (e.g., BSVs, pendulum valves, and other chamber or flow isolation valves), and can also be used as seals or other molded articles in gaseous and / or liquid applications in medical cleanroom applications, downhole and other oilfield applications, and fluid handling chemical applications. As used herein, "seal" is intended to include the general category of seals and sealing assemblies, including O-rings, gaskets, V-rings, inserts, sealing or shielding layers, and other similar products, and is not intended to be limiting unless a specific type of seal is explicitly indicated. "Article of manufacture" is intended to cover parts, components, devices, and seals used alone or in combination with other existing components as part of a product formed using the components disclosed herein.

[0083] Regarding articles such as seals, a seal is provided that can sensitively respond to applied compressive stress (such as when subjected to a load) by means of its conductivity level. This seal can act as a pressure sensor, and its degradation can be assessed by the relationship between compressive stress and conductivity at a baseline under the presence and absence of an applied load (when new). This allows the seal to be replaced before its lifespan and performance are affected by repeated use and / or harsh conditions. While the self-sensing seals, methods, and systems described herein for monitoring the lifespan of the seals described herein are particularly applicable to seals such as vacuum seals or KF-type seals and for use in semiconductor manufacturing valve assemblies, including BSVs, and other semiconductor seals, they can also be used in similar valves used in fluid handling and other environments, especially where seal life is critical to operation and where the seal is subjected to pressure, strain, and environmental or environmental operating conditions, in which the seal undergoes degradation. This is a particularly difficult problem in semiconductor manufacturing and specifically focuses on semiconductor sealing assemblies such as BSVs, pendulum valves, and isolation valves. It should be understood that, based on this disclosure, the specific examples described herein can be applied to other similar valve sealing assemblies and end applications.

[0084] Examples of gate valves and slit valves including seals are known in this art, and any of these designs can be used to implement articles made from the components and methods described herein. Examples of commercially acceptable gates of this nature are available from Greene, Tweed, Inc., Kulpsville, Pennsylvania, USA, and are also described, for example, in U.S. Patent Application Publication No. 2012 / 0100379A1, which is incorporated herein by reference in its relevant portion. Other BSVs and gate valves having known or undeveloped seals in connection with engagements or other assemblies can be used in the systems and methods described herein.

[0085] These gates and slit valves are generally made of metallic door materials (metal or metal blends), with aluminum or stainless steel being preferred materials. The seals in these gates are preferably made of resilient materials or materials that exhibit resilient properties under operating conditions. Typical materials used are fluoroelastomers, perfluoroelastomers, and silicone elastomers, including fluorosilicones. Additionally, support rings or seals may be included, such as standalone fluoropolymers (e.g., polytetrafluoroethylene) or as supporting and protective seals for the main seals formed from elastomers or materials with resilient properties.

[0086] These seals can be mechanically attached, joined, or molded into place on doors, and various materials and door assemblies are commercially available.

[0087] The carbon nanostructure additives used herein are preferably cross-linked carbon nanotubes formed to have a three-dimensional branched chain structure and, more preferably, to be interconnected to form a three-dimensional branched carbon structure network, included within such structures. These materials differ from standard single-walled and multi-walled carbon nanotubes and carbon allotropes, such as plate-like carbon and fluorinated graphite. In a preferred embodiment herein, such three-dimensional, branched carbon nanostructure additives with a carbon content ≥ about 97% and a bulk density of about 0.135 g / cm³ are used, but these properties may vary depending on the bonding and branching that occurs during the manufacturing process. One suitable carbon nanostructure used herein is available from Cabot as an aggregated granule for Athlos™ carbon nanostructures. Other suitable materials are also available from Cabot, and / or can be made or manufactured and are commercially available. Descriptions of branched and bonded carbon nanostructures and their preparation methods can be found in U.S. Patents 9,107,272, 9,111,658, 9,447,259 and 9,650,501, the relevant portions of the disclosures of each of these patents regarding methods for manufacturing and preparing branched and bonded carbon nanostructures are incorporated herein by reference.

[0088] Due to the dielectric properties of certain curable polymer compositions and the properties of the elastomers obtained upon curing, especially the properties of fluoroelastomers and / or perfluoroelastomers, the self-conductive conductivity level can only be sensed by branched chains and three-dimensional carbon nanostructure additives when the polymer is under high load. However, in other applications, such as for the preparation of pressure sensing applications, the lower load of such carbon nanostructure additives is indicated.

[0089] In addition to the self-sensing end applications and other uses of QTC components mentioned above and elsewhere in this article, when articles are formed using a higher load of the conductive nanostructure additives described herein, such articles can be formed in seals or sealing assemblies, including gaskets, covers, and various other component portions having polymer or elastomeric materials to provide a volume resistivity of about 0.5 ohm-cm or less, thereby providing useful EMI and / or RFI shielding effects.

[0090] For EMI and / or RFI shielding applications, the load may vary depending on the curable polymer selected. Among various polymers, the composition may incorporate about 0.1 to about 300 parts by weight of carbon nanostructure per 100 parts by weight of at least one polymer or curable polymer, preferably about 0.25 to about 250 parts by weight, more preferably about 0.5 to about 250 parts by weight, or about 0.5 to about 80 parts by weight of carbon nanostructure additive per 100 parts by weight of at least one polymer or curable polymer.

[0091] Preferably, in polymers such as curable perfluoropolymers and curable fluoropolymers, about 10 to about 50 parts by weight of the polymer or curable polymer per 100 parts by weight can be used to provide a better degree of shielding by absorbing or reflecting EMI and / or RFI. For curable perfluoropolymers and other curable fluoropolymers that may be generally more difficult to load at high levels, about 20 to about 40 parts by weight of the curable polymer per 100 parts by weight can be used.

[0092] In a preferred embodiment, the amount of carbon nanostructure additives used can be varied to attempt to achieve the best shielding effect, and, where possible, maintain the effective elastic and / or mechanical properties of the formed article to be used for the final shielding application, depending on the type of shielding component or assembly being manufactured. With this material, the required maximum volume resistivity level for effective shielding is approximately 0.5 ohm-cm, although this can be varied for different end applications. In perfluoropolymers, for example, using between approximately 20 and approximately 40 parts per 100 parts of perfluoropolymer in the composition will maintain the desired balance of mechanical and elastic properties while allowing a volume resistivity of approximately 0.5 ohm-cm.

[0093] After curing with such carbon nanostructure additives in curable polymers, elastic articles of various shapes and configurations according to the present invention can be formed, such as seals, gaskets, EMI or RFI shielding devices or components thereof, such as EMI or RFI filter seals or filter covers. Furthermore, shielding components formed from other polymer matrix materials using the carbon nanostructures described herein are also within the scope of this invention.

[0094] When at least one of the carbon nanostructure additives described herein is incorporated into a curable polymer or other polymer matrix or dissipative conductive polymer or elastomer used to generate the QTC effect, a lower loading of the carbon nanostructure additive is indicated in the invention herein. For example, about 1 to about 30 parts by weight of the carbon nanostructure additive per 100 parts by weight of the curable polymer or polymer matrix polymer can be used to provide a lower level of conductivity than required in shielding applications. Preferably, about 1 to about 15 parts by weight of the carbon nanostructure additive are used per 100 parts by weight of the curable polymer or polymer matrix polymer.

[0095] For some applications with lower conductivity, such as antistatic dissipative materials that can be used in automotive, aerospace, oilfield, medical and pharmaceutical or other end-use applications, where it is required that the conductive material can dissipate charge to avoid generating sparks or other problems but can withstand the environment in which the specific elastomeric matrix is ​​located, such a low loading of up to about 15 parts by weight of additive per 100 parts by weight of any base polymer is acceptable.

[0096] When using compositions for the QTC effect, such as those that allow charged particles to jump as in a QTC-formed article when compressed, the composition is indicated to contain at least about 2 parts, more preferably at least about 3 parts, and most preferably at least about 4 parts to about 30 parts or about 15 parts by weight of the polymer or curable polymer per 100 parts by weight. In some specific examples, compositions may contain about 4 parts by weight to about 20 parts by weight, and more preferably about 4 to about 15 parts by weight of the curable polymer per 100 parts by weight.

[0097] To generate the QTC effect, three-dimensional, branched, and cross-linked carbon nanostructures with longer tube interconnections create a denser array of QTC electron carrying options throughout the article. Since the elastomer used can be selected to act as a dielectric during use and in the absence of compressive stress such as applied loads, the QTC effect in such elastomers can be achieved by applied compressive stress without the need for dielectric additives and / or needle-like carbon as described in prior art QTC composites. The polymer matrix or elastomer matrix in the cured article provides a dielectric environment that is activated by applying compressive stress to a compressible dielectric elastomer material to achieve a proportional conductivity level within the matrix. This level can be measured in real-time during use, based on the degree of applied compressive stress, and the relationship between compressive stress and the content of carbon nanostructure additives in the elastomer can be quantified and analyzed to determine seal life.

[0098] For example, in use, a finished molded product such as an elastic seal can be placed in electrical connection with a circuit having an applied voltage and a known resistance. This allows for the measurement of the seal's volume resistivity or conductivity before compressive stress is applied, either by applying an external load or during use by compressing moving parts around the seal within its gland. It also allows for the measurement of the same properties over time for a given amount of carbon nanostructure additive in the elastomer. The resulting relationships can be used to analyze when the additive and elastomer matrix begin to deteriorate and when resistivity and conductivity change. These measurements can then be used to monitor the seal's performance and lifespan during use to determine when replacement is necessary.

[0099] By providing articles of this kind formed from the components described herein, seals, gaskets, or other sealing assemblies or component parts (such as polymer or elastomer components) can be manufactured that are "self-sensing," meaning that their own characteristics are measured and evaluated in real time during use to determine seal life and performance without the need for external sensors, embedded sensors affecting characteristics (such as sealing properties), or complex sensor arrangements and relationships around or near the seal, either on doors (such as BSV doors or gates) or in reaction chambers or the surrounding environment. Furthermore, the carbon nanostructures described herein contribute to achieving more consistent conductivity properties throughout the polymer or elastomer matrix of the formed article.

[0100] Further use of the compositions herein to form articles with QTC effect from polymers or elastomers can be used to form self-sensing articles, such as seals, using different polymers and elastomers, and for other known QTC material applications formed from prior art QTC composites, such as for medical devices, such as blood pressure cuffs, pressure sensing controls for clothing, audio or telephone devices for playing digital audio or video files, converters for downhole tools in oilfield applications (such as U.S. Patent No. 8,893,547), sports training dummies with sensors for boxing or fencing, sports training shoes for evaluation, touch sensors and prostheses based on robotics, and smart seals, and for various medical and pharmaceutical applications.

[0101] In addition to the carbon nanostructure additives described herein, such curable polymer compositions include at least one curable polymer incorporated into the composition prior to curing. In some preferred embodiments herein, other such compositions may also include crosslinking agents or curing agents that enable the curable polymer to crosslink to form an elastomer. Crosslinking may also be induced or performed using techniques known or under development in the related art, including curing various commercial products using curing systems that interact with their functional crosslinking groups, including those products indicated by manufacturers of commercial curable polymers as further described below.

[0102] For the polymer-based compositions or the elastomeric compositions formed using curable polymer compositions (once cured) mentioned herein, such polymer and elastomeric compositions can provide polymer or elastomeric articles that can be used in a variety of end applications (including those mentioned above), including seals such as O-rings, gaskets, component parts, coatings, layers and the like.

[0103] Other additives used may vary depending on the non-curable or curable polymer system chosen. For example, when cured as an elastomer, different curable polymers have different mechanical and elastic properties and can tolerate different additives, processing aids, fillers, pigments, and the like, or are best used with different additives, processing aids, fillers, pigments, and the like. The addition of such polymers and elastomer compositions is generally known.

[0104] Since the carbon nanostructures described herein can be used to impart unique electrical and resistive properties to polymers or curable polymers and / or curable elastomer matrices, whether as shielding additives, dissipative additives or QTC additives, the additives used are preferably additives that may complement or enhance their effects or substantially do not affect the desired electrical and resistive properties and will not negatively or excessively affect the mechanical or elastic properties of the resulting article for its intended end use.

[0105] The components described herein may incorporate elastic or inelastic matrix materials. Preferably, in EMI and / or RFI shielding assemblies, the matrix is ​​an elastomer, and in other preferred embodiments, the matrix is ​​a fluoroelastomer, including elastic perfluoropolyethers, fluorosilicones, perfluoroelastomers, and blends of these materials and blends of more than one type of these materials. The QTC component may be elastic or inelastic, but in the case of forming a dedicated self-sensing seal formed from the QTC component, it is preferred that the matrix is ​​also elastic.

[0106] Regarding suitable curable polymers, such materials include those that can be crosslinked or cured by functional groups to form an elastomeric matrix material. For example, suitable elastomers include silicones, fluorosilicones, nitrile rubbers, olefin rubbers (such as ethylene-propylene-diene rubber or ethylene-propylene rubber), fluoroelastomers including perfluoropolyether elastomers, perfluoroelastomers, polyurethanes, and their copolymers and blends.

[0107] Such elastomers are formed from curable polymers, copolymers thereof, and blends, including those formed from monomers containing silicon and / or fluorine, curable polymers having at least one acrylonitrile monomer and at least one butadiene monomer, curable polymers having at least one olefin monomer, and curable polymers having at least one fluorinated monomer and / or perfluorinated monomer. Such materials can be copolymerized, blended, and / or functionalized to form curable polymers. Preferably, at least one of the monomers used to form at least one curable polymer has one or more functional groups for crosslinking. Crosslinking can be carried out chemically using radiation or heating and / or by adding one or more crosslinking compounds that, upon chemical reaction with crosslinking sites on the functional groups of the monomers, can crosslink various monomers to form a crosslinked polymer.

[0108] As used herein, "curing" is intended to encompass any method by which a curable polymer is given an elastomeric structure through vulcanization, chemical crosslinking, thermal crosslinking, catalytic crosslinking, radiation crosslinking, and the like. Upon curing, the curable polymer forms an elastomer. As used herein, "elastomeric" (sometimes also referred to as rubber) is intended to mean a polymer material that exhibits viscoelastic properties and deforms under stress but recovers a portion of its initial form after the stress is removed.

[0109] As used herein, "compression deformation" refers to the tendency of an elastomeric material to retain its deformation and not return to its original shape after the deformation compressive load has been removed. The compression deformation value represents the percentage of the material's original deflection that it fails to recover. For example, a 0% compression deformation value indicates that the material fully recovers to its original shape after the deformation compressive load is removed. Conversely, a 100% compression deformation value indicates that the material does not recover at all from the applied deformation compressive load. A 30% compression deformation value indicates that 70% of the original deflection has been recovered. Higher compression deformation values ​​generally indicate the likelihood of seal leakage.

[0110] Other elastomer properties typically measured include elongation at break, tensile modulus, and other physical properties. The thermal behavior of the elastomer and the effect of its curing system on these properties are also applicable to evaluating elastomers for different end-use applications.

[0111] The terms “uncured” or “curable” refer to curable polymers used in the compositions herein that have not yet undergone any substantial degree of crosslinking to cure the material sufficiently for the intended end application.

[0112] Further information is provided below regarding polymers that can be used in the applicable categories described herein, including information on the matrix materials mentioned above applicable to QTC components or EMI and / or RFI shielding components.

[0113] The silicones used herein can be formed from any of a variety of silicone homopolymers and copolymers that can be cured to form silicone elastomers (also known as silicone rubbers). Silicone is generally a polymer incorporating at least silicon, oxygen, and hydrogen into its chemical structure. Curable silicone polymers (silicones) that can be used to form silicone elastomers include polymers having a backbone that are classified as VMQ (silicone), PVMQ (phenyl silicone), and FVMQ (fluorosilicone) in ASTM D1418-17 according to the Standard Rubber Nomenclature Definitions provided by ASTM International. However, silicones that are not easily classified by ASTM D1418-17 may also be used, provided they exhibit suitable manufacturing characteristics. Any such silicone, fluorosilicone, or phenyl silicone may be used in this invention.

[0114] The silicone used to form silicone rubber can be cured using a variety of curing systems, including catalyst curing systems, typically using platinum-based catalysts, condensation curing systems, peroxide curing systems, and oxime curing systems.

[0115] In platinum catalyst curing, crosslinking is performed using functional silicone polymers, such as vinyl-functional silicones and hydride-functional silicones formed via addition reactions. These reactions leave no byproducts and are therefore a preferred curing method in this technology.

[0116] Condensation systems typically involve cross-linked materials activated in some manner. In common single-component systems, functional silicones are used, which undergo hydrolysis upon contact with water at room temperature, and the hydrolyzable groups (hydroxyl or silanol groups) initiate a curing reaction. Once initiated, the hydrolysis continues until curing is complete and can occur at room temperature. Cross-linked materials, including condensation systems, comprise functional silanes with active oxygen-containing groups (such as alkoxy, acetoxy, ester, alkenoxy, or oxime silanes), such as methyltrimethoxysilane, methyltriacetoxysilane, and similar materials. If desired, organometallic catalysts, such as tetraalkoxy titanates, chelated titanates, and tin catalysts (e.g., dibutyltin dilaurate and acetyl oxytin), can also be used to catalyze these substituted and / or functionalized groups.

[0117] In the two-component condensation process, the crosslinking material and any catalyst are retained in one container, while the curable silicone polymer composition (which does not contain the other material) is retained in a separate container. Curing is initiated when the materials are mixed in both containers.

[0118] Other silicone curing systems used to form silicone elastomers include peroxide curing systems that crosslink via reactive silicone sites to form Si-R-Si bonds between silicone chains. Commercial silicones applicable herein include NuSil® from Nusil Silicone Technology, which can be used in QTC or EMI and / or RF shielding applications, and PDMS-Sylgard® from Dow-Corning, which can be used in QTC end applications.

[0119] The silicone polymers used herein include one or more of the following: polysiloxanes, polyalkylsiloxanes, polydialkylsiloxanes, polyarylsiloxanes, polyarylalkylsiloxanes, and blends, mixtures, or copolymers of these materials with each other or with other curable polymers as described herein. Furthermore, such silicone-containing polymers may have one or more hydrogen atoms or one or more silicon-bonded bonding groups on silicon atoms in a backbone substituted with one or more groups, each of which may be further functionalized or further substituted or used for crosslinking. These substituted groups or functional groups may be branched and / or straight-chain groups, including but not limited to hydroxyl, alkyl, alkenyl, alkoxy, alkenyloxy, alkynyloxy, aryloxy, arylalkyl, arylalkoxy, arylalenooxy, vinyl, carboxyl, carbonyl, halogen, heterocyclic, and fluorinated or perfluorinated groups.

[0120] The components of silicone-containing polymers included herein may include curing agents, curing initiators, crosslinking agents (such as hydrolytic crosslinking agents), curing catalysts (such as organic peroxides), and other curing system components as indicated above and known or to be developed in this art.

[0121] In addition to at least one carbon nanostructure additive in the compositions described herein, other various additives and / or modifiers that can be used in curable silicone or fluorosilicone compositions include, for example, but not limited to, siloxane additives, ultra-high molecular weight siloxane additives, clarifying agents, processing aids, stabilizers, colorants such as pigments and dyes, other fillers such as non-conductive and / or dielectric carbon black, quartz, pyrolytic silica, standard carbon nanotubes, glass fibers and coupling agents as applicable, aromatic polyamide fibers, olefin fibers, carbon fibers, UV absorbers, UV stabilizers, and lubricants. Examples of suitable silicone-containing polymer additives and / or modifiers include waxes, fatty acids and other rheology modifiers, flame retardants, polyols, amides, fluoropolymers, fluorinated or perfluorinated polymer additives, nano-silica (i.e., nano-silica) particles, polysiloxanes, anti-blocking agents such as silica and talc, brighteners, dispersants, wetting agents, compatibilizers, and any other suitable known or developed silicone-containing polymer additives and / or modifiers for providing desired compositional properties, provided that the selection or amount of such additives does not hinder, prevent, or materially affect or impede the desired level of conductivity intended for the final application. Other conductive additives may also be used to improve conductivity properties and are further described below in this invention.

[0122] For example, for QTC applications, the level of potentially conductive or semiconductive materials used that would affect the QTC effect in the self-sensing article will not be specified. Furthermore, if silicone is used in the shielding end application, a higher loading level of carbon nanostructure additives will be required, but not so much that the filler would excessively increase the bulk resistivity. Finally, in these and other end applications, the amount of filler is generally controlled to achieve the compressive stress and resistivity changes expected for the intended end application.

[0123] Preferred additives used in the silicone polymer compositions or compositions herein are curing agents, such as peroxide curing agents, typically incorporated in amounts of about 0.5 to about 5.5 parts per 100 parts of silicone polymer, or in other systems, platinum catalysts in amounts of about 0.0005 to about 0.0015 parts per 100 parts of silicone polymer. Other preferred additives include colorants and pigments, such as white (titanium oxide), yellow (iron oxide or azo iron), blue (phthalocyanine GS or ultramarine) and / or green (phthalocyanine BS), in amounts that may vary, but typically at most about 1.0 part per 100 parts of silicone polymer individually, or at most about 1.5 parts per 100 parts of silicone polymer in total.

[0124] Such additives, other than those used in any particular curing system, are generally selected as appropriate when used in compositions containing carbon nanostructure additives, and may be incorporated in an amount of up to about 50% by weight of additives other than curing agents and carbon nanostructure additives, subject to the limitation that they do not overload the polymer or impede or materially affect the intended function of the final application.

[0125] Depending on the curing system used, the degree of curing agent application may be adjusted for the system. Since such curing systems are known in this art, the same systems as those described above may be used herein. Preferred examples of silicones used in this invention include commercially available silicones, such as those manufactured by Stockwell Elastomerics of Pennsylvania and Primasil Silicones Ltd. of the United Kingdom, which may be used and combined as recommended by their manufacturers.

[0126] Acrylonitrile rubbers, such as acrylonitrile-butadiene and its copolymers and variants, and olefin rubbers (such as EPDM or EPR), as well as other olefin rubbers known or to be developed in this art (such as Nipol® grades manufactured by Zeon, Keltan® grades manufactured by ArlanXeo Performance Elastomers, and Vistalon® manufactured by ExxonMobil), are known and commercially available for use in this invention. Such compositions and their additives are known for use in component parts. Such elastomers are particularly suitable for the QTC compositions and components described herein.

[0127] For QTC or EMI and / or RFI shielding end applications, the curable fluoropolymer can be any suitable curable fluoropolymer with varying fluorine content, including curable perfluoropolymers and curable perfluoropolyethers (PFPE) or PFPE copolymers having at least one monomer unit (CnF2nO), wherein such fluoropolymers preferably include functional groups or reactive monomers along the curable polymer backbone or depending on the curable polymer backbone.

[0128] In general, these fluoropolymers provide materials suitable for relatively harsh environments, such as those encountered in oilfield industrial applications, petrochemical processing, semiconductor manufacturing, gas and food processing, life sciences, and other clean environments. Among the various end-uses described herein, the use of carbon nanostructures in cleaning materials offers excellent electrical conductivity while providing low levels of particulate contamination in the environment, and maintains good processability even with higher carbon nanostructure additives described herein.

[0129] The curable fluoropolymers that can be used are those classified in ASTM D1418-17 as defined by the standard rubber nomenclature provided by ASTM International. Standard FKM polymers named according to this type of elastomer typically have at least two monomers, one of which is fluorinated, and preferably both are fluorinated to some extent, with at least one curing site monomer used for vulcanization. The at least two monomers preferably include vinylidene fluoride and hexafluoropropylene or similar fluorinated olefins, but may also include a variety of other monomers known or under development in this art. The fluoroelastomer composition may also include at least one curing agent capable of undergoing a crosslinking reaction with the functional groups in the curing site monomer of the fluoroelastomer. As noted above, PFPE monomers and comonomers may also be used.

[0130] Regarding the FKM described herein, such curing site monomers may include a type of curing site monomer that can be cured by a peroxide or other curing system. With regard to peroxide curing systems, such curing site monomers may have functional groups containing halogenated substances such as Br or I in the curing site functional groups. Although at least two of the monomers in the FKM may be hexafluoropropylene (HFP) and vinylidene fluoride (VF2), other typical monomers may be used to form a variety of fluoropolymers known in this art, and the curing site monomers and curing systems may vary. Such systems are known in this art.

[0131] The curable fluoropolymer may be radiocrosslinkable, but is preferably crosslinkable (curable) via a curing system, wherein a curing agent is added that can react with the functional groups in the monomer at the curing site to form an elastic material. Depending on the application, at least one of a second curing agent, a co-curing agent, and / or a curing accelerator may also be used. Depending on the desired final properties, the compositions herein may comprise a single curable fluoropolymer or a combination of at least two curable fluoropolymers and / or curable perfluoropolymers as further described below, in the form of, for example, polymer blends, graft compositions or blends, copolymers, and the like.

[0132] The curable fluoropolymers used in the compositions herein may, as appropriate, include additional such polymers in blended or graft / copolymer compositions as indicated above. Furthermore, the polymer backbone may include monomers with multiple curing sites along the chain to provide one or more different functional groups for crosslinking; however, one of such groups used in the invention herein is preferably curable by a peroxide curing system. The composition may also include curing agents, co-curing agents, and / or accelerators to facilitate the crosslinking reaction. Additional curing sites and curing systems may be provided to monomers with the same or different curing sites, such as curing sites that react with a bisphenyl-based curing system for generating crosslinks, for example, those curing sites having nitrogen-containing reactive groups, preferably also having peroxide-curable functional groups. Therefore, while the invention herein discusses various preferred curing agents (also referred to herein as crosslinking agents or curing agents), when using additional curing sites known in this art, other curing agents capable of curing such alternative curing sites may be used in addition to the preferred organic peroxide-based curing agents and co-curing agents described herein. Further description of this type of curing system is provided below.

[0133] One or more curable fluoropolymers may be present in such compositions. These polymers are formed by polymerizing or copolymerizing one or more fluorinated monomers. Various techniques known in this art (direct polymerization, emulsion polymerization and / or free radical-initiated polymerization, latex polymerization, etc.) can be used to form such polymers.

[0134] Curable fluoropolymers can be formed by polymerizing two or more monomers, preferably one of which is at least partially fluorinated, but fully fluorinated monomers may also be used. For example, HFP and VF2 are preferably combined with tetrafluoroethylene (TFE) or one or more perfluoroalkyl vinyl ethers (PAVE) or similar monomers and at least one monomer that serves as a curing site monomer to allow curing (i.e., at least one fluoropolymer curing site monomer). Fluoroelastomer compositions as described herein may include any suitable standard curable fluoroelastomer (FKM) that can be cured preferably using a curing system and one or more other curing agents as described herein to form a fluoroelastomer. Examples of suitable curable FKM fluoropolymers include those sold under the trade names Tecnoflon® PL958, Tecnoflon® PFR-LT, Tecnoflon® FOR 801HS (each purchased from Solvay Solexis S.A., Italy), Dyneon® FE5610, or FC2211 (purchased from 3M), and other similar fluoropolymers that can be cured by a peroxide curing system or a bisphenyl system when used in the compositions described herein. Other suppliers of such materials include Daikin Industries, Japan; 3M, Minnesota; Chemours, Delaware; and EI DuPont de Nemours, Delaware, etc. These FKM polymers are not fully fluorinated along the polymer backbone.

[0135] In certain specific instances, such as in end applications including clean environments, at least one first curable fluoropolymer may be a curable perfluoropolymer suitable for forming a perfluoroelastomer. The compositions herein, whether curable fluoropolymer compositions or perfluoropolymer compositions, may comprise only one fluoropolymer or perfluoropolymer, or may comprise two or more such fluoropolymers or perfluoropolymers in compositional form, which, upon use and / or curing, will form a single fluoroelastomer or perfluoroelastomer, or, when used with two or more, will form a perfluoroelastomer blend composition or copolymer for curing. Other curable fluoropolymers may be blended with curable perfluoropolymers to obtain partially fluorinated blended fluoroelastomers.

[0136] As used in this application, unless otherwise indicated, "perfluoroelastomer" or "cured perfluoroelastomer" includes any cured elastomer material or composition formed by curing a curable perfluoropolymer (such as a preferred curable perfluoropolymer among the curable compositions described herein).

[0137] The "curable perfluoropolymer" (sometimes referred to in this art as a "perfluoroelastomer" or more appropriately as a "perfluoroelastomer adhesive") suitable for forming cured perfluoroelastomers is a polymer that is substantially fully fluorinated, and preferably fully perfluorinated along its polymer backbone. Based on this invention, it should be understood that, due to the use of hydrogen as part of the functional crosslinking groups, some residual hydrogen may be present in some perfluoroelastomers within the crosslinking of such materials. Cured materials, such as perfluoroelastomers, have a crosslinked polymer structure.

[0138] The preferred perfluoroelastomer compositions used herein are formed by polymerizing one or more perfluorinated monomers from a curable perfluoropolymer that forms a cured perfluoroelastomer upon curing. One of these perfluorinated monomers is preferably a perfluorinated curing site monomer having a curing site, as noted above, i.e., a curable functional group. The functional group may be or may include reactive groups that do not require perfluorination. Two or more curable fluoropolymers or perfluoropolymers, and preferably at least one curing agent (curing reagent) present herein, may preferably be combined in the composition, which is subsequently cured to form the resulting cross-linked cured fluoroelastomer composition, preferably, as described herein.

[0139] As used herein, a curable fluoroelastomer composition may be a curable perfluoropolymer composition, which is a blend and combination of two or more curable polymers, each of which (if perfluorinated) is formed by polymerizing two or more perfluorinated monomers, including at least one perfluorinated curing site monomer having at least one functional group (curing site) to allow curing. According to the definition of rubber standardized by American Standardized Testing Methods (ASTM) and as described above in ASTM Standard D1418-17, such curable perfluoropolymer materials are also commonly referred to as FFKM, and these documents are incorporated herein by reference in relevant sections.

[0140] As described herein, the present invention includes curable fluorinated elastomer compositions, preferably curable perfluoroelastomer compositions and cured perfluoroelastomer compositions, and molded articles formed from such curable fluorinated elastomer compositions.

[0141] Such perfluoroelastomer compositions preferably include at least one, and more preferably two or more, curable perfluoropolymers, preferably perfluoropolymers, wherein at least one of the perfluoropolymers has a high content of tetrafluoroethylene (TFE). Other suitable comonomers may include other olefinic unsaturated fluorinated monomers. The degree of TFE used in the perfluoropolymer may vary for different final properties. Each polymer may also preferably have one or more perfluoroalkylvinyl ethers (PAVEs), which include alkyl or alkoxy groups that may be linear, straight, or branched and may also include ether bonds. Preferred PAVEs used herein include, for example, perfluoromethylvinyl ether (PMVE), perfluoroethylvinyl ether (PEVE), perfluoropropylvinyl ether (PPVE), perfluoromethoxyvinyl ether, and other similar compounds. Particularly preferred PAVEs are PMVE, PEVE, and PPVE, and PMVE is most preferably the PAVE that provides excellent mechanical strength to articles formed from cured curable compositions herein. PAVEs may be used alone or in combination with the above-described PAVE types within a curable perfluoropolymer and in the final curable composition, provided that the use is consistent with the invention as described herein.

[0142] Preferred perfluoropolymers are copolymers of TFE, at least one PAVE, and at least one perfluorinated curing site monomer having curing sites or functional groups to allow crosslinking of the curable polymer. The curing site monomer can be of various types having the preferred curing sites indicated herein. Preferred curing sites are preferably curing sites having nitrogen-containing groups; however, other curing site groups, such as carboxyl, alkyl carbonyl, or halogenated groups having, for example, iodine or bromine, and other curing sites known in this art, can also be used, particularly because additional curable fluoropolymers or perfluoropolymers besides the first and / or second curable perfluoropolymers can be provided to the composition.

[0143] The present invention also provides for radiation curing or the use of various curing agents (also referred to herein as crosslinking agents or curing reagents). If other curing sites known in this art are used, other curing agents capable of curing these alternative curing sites may also be used. For example, peroxide curing systems, such as organic peroxide-based curing systems, and related peroxide co-curing agents can be used with halogenated functional curing site groups. In other specific examples, at least one of the perfluoropolymers includes a nitrogen-containing curing site.

[0144] Exemplary curing site monomers are listed below and can be used in the curable fluoropolymers or curable perfluoropolymers described herein for use in curable compositions, most of which are structurally based on PAVE and have reactive sites. Although the polymer can vary, a preferred structure is one having the following structure (A): CF 2=CFO(CF 2CF(CF 3)O) m(CF 2) nX 1(A) Where m is 0 or an integer from 1 to 5, n is an integer from 1 to 5, and X 1 is a nitrogen-containing group, such as a nitrile or cyano group. However, carboxyl, alkoxycarbonyl, or halogenated end groups can also be used as X 1.

[0145] Preferably, the curing site monosystem in any curable fluoropolymer or curable perfluoropolymer, or in a blend of any two of the first and second such curable perfluoropolymers, is according to (A) mentioned above, where m is 0 and n is 5. The curing site or functional group X1 (e.g., a nitrogen-containing group) indicated herein includes a reaction site for crosslinking when reacting with a curing agent. Compounds according to formula (A) can be used alone or in various combinations as appropriate. From a crosslinking point of view, preferably, the crosslinking functional group is a nitrogen-containing group, more preferably a nitrile group.

[0146] Other examples of monomers with curing sites according to formula (A) include the following formulas (1) to (17): CY 2=CY(CF 2) nX 2(1) Where Y is H or F, and n is an integer from 1 to 8. CF 2=CFCF 2R f 2-X 2(2) Where Rf2 is (-CF2)n-, -(OCF2)n-, and n is an integer from 0 or 1 to about 5. CF 2=CFCF 2(OCF(CF 3)CF 2) m(OCH 2CF 2CF 2) nOCH 2CF 2-X 2(3) Where m is an integer from 0 or 1 to 5 and n is an integer from 0 or 1 to 5. CF 2=CFCF 2(OCH 2CF 2CF 2) m(OCF(CF 3)CF 2) nOCF(CF 2) -X 2(4) Where m is an integer from 0 or 1 to 5, and n is an integer from 0 or 1 to 5. CF 2=CF(OCF 2CF(CF 3)) mO(CF 2) nX 2(5) Where m is an integer from 0 or 1 to 5, and n is an integer from 1 to 8. CF 2=CF(OCF 2CF(CF 3)) m- X 2(6) Where m is an integer from 1 to 5. CF 2=CFOCF 2(CF(CF 3)OCF 2) nCF(-X 2)CF 3(7) where n is an integer from 1 to 4. CF 2=CFO(CF 2) nOCF(CF 3)-X 2(8) Where n is an integer from 2 to 5. CF 2=CFO(CF 2) n-(C 6H 4)-X 2(9) Where n is an integer from 1 to 6. CF 2=CF(OCF 2CF(CF 3)) nOCF 2CF(CF 3)-X 2(10) Where n is an integer from 1 to 2. CH 2=CFCF 2O(CF(CF 3)CF 2O) nCF(CF 3)-X 2(11) Where n is an integer from 0 or 1 to approximately 5. CF 2=CFO(CF 2CF(CF 3)O) m(CF 2) n=X 2(12) Where m is an integer from 0 or 1 to 4 and n is an integer from 1 to 5. CH 2=CFCF 2OCF(CF 3)OCF(CF 3)-X 2(13) CH 2=CFCF 2OCH 2CF 2-X 2(14) CF 2=CFO(CF 2CF(CF 3)O) mCF 2CF(CF 3)-X 2(15) Where m is an integer greater than 0. CF 2=CFOCF(CF 3)CF 2O(CF 2) nX 2(16) where n is an integer that is at least 1. CF 2=CFOCF 2OCF 2CF(CF 3))OCF 2-X 2(17) X2 can be a monomeric reactive subunit such as a nitrile (-CN), carboxyl (-COOH), alkoxycarbonyl (-COOR 5, where R 5 is an alkyl group of 1 to 10 carbon atoms, which may be fluorinated or perfluorinated), halogen, or alkylated halogen (I or Br, CH 2I, and the like). When used as a curing site monomer, the portion of the perfluorinated compound in the curing site monomer backbone located in the polymer backbone typically does not have hydrogen atoms. Such curing site monomers are used if the perfluorinated elastomer requires excellent heat resistance resulting from curing the perfluorinated polymer and prevention of molecular weight reduction due to chain transfer during the synthesis of the perfluorinated elastomer via polymerization. Furthermore, from the perspective of providing excellent polymerization reactivity with TFE, compounds with the CF 2=CFO- structure are preferred.

[0147] For better crosslinking reactivity, suitable monomers for curing sites may include those having nitrogen-containing curing sites (such as nitrile or cyano curing sites). However, monomers with curing sites (having multiple and different backbones in addition to those mentioned above) and having carboxyl, alkoxycarbonyl, COOH, and other similar curing sites known in this art and yet to be developed may also be used. Monomers for curing sites may be used alone or in different combinations.

[0148] Depending on the desired properties, perfluoropolymers that may be used herein include TFE, with a molar percentage of TFE in the perfluoropolymer compound of about 50, about 95 molars, or about 40 to about 80%. Such perfluoropolymers may also incorporate another, preferably perfluorinated, comonomer, such as PAVE, many of which are known in the art and are available herein. Various PAVEs can be used in curable polymers for use in the compositions herein. In one specific example, the curing site monomer may also be a perfluorinated curing site monomer having one or more curing site monomers, such monomers being cyano. In one specific example, two such curing site groups may be present, such as a curing site having a primary cyano curing site group and a curing site having a secondary cyano curing site group.

[0149] Suitable perfluoropolymers are available from Daikin Industries, Ltd. and are described in U.S. Patent Nos. 6,518,366 and 6,878,778 and U.S. Patent Application Publication No. 2008-0287627, the relevant portions of which are incorporated herein by reference. The preferred specific examples used herein include additional commercially available perfluoropolymers comprising at least two curing site monomers, which are available from the Federal State Unitary Enterprise SV Lebedev Institute of Synthetic Rubber of Petersburg, Russia, and Lodestar of the United States, as described in the scope of International Publication No. WO 00 / 29479 A1, for the relevant part of such perfluoroelastomers incorporated herein, and are available as commercially available perfluoroelastomers from the Federal State Unitary Enterprise SV Lebedev Institute of Synthetic Rubber as PFK-65, PFK-100, PFK-200, PFK-300 and other similar polymers. Suitable perfluoropolymers may also be available from Dyneon as PFE 300Z, PFE 133TB or PFE8IT, depending on the desired end properties.

[0150] In some specific examples herein, a curable perfluoropolymer may be used with a TFE content ranging from about 40 to about 80 mol%, a PAVE content ranging from about 20 to about 60%, and wherein each of the curing site monomers may be present in an amount totaling from about 0.1 mol% to about 10 mol%, or each in an amount from about 0.1 to about 6 mol%. In another specific example, a first curing site monomer may be present in an amount from about 0.2 to about 2.0 mol%, and a second curing site monomer may be present in an amount from about 0.5 to about 5.0 mol%.

[0151] In some specific instances, two or more curable fluoropolymers may be used in blend form, wherein a polymer such as the polymers mentioned above may be used with a second curable fluoropolymer or curable perfluoropolymer used herein, which may be the same as or different from the polymers mentioned above, and the second curable polymer may have, but does not necessarily have, the same TFE or PAVE content. Preferably, a second perfluoropolymer or fluoropolymer may be used, and the second perfluoropolymer or fluoropolymer may be a perfluoropolymer or fluoropolymer incorporating a fluoroplastic material (such as a fluoroplastic). Fluoroplastic particles can be provided in various forms and using various technologies. Fluoroplastics, such as PTFE and its copolymers (FEP and PFA type polymers), core-shell or other modified fluoropolymers, and fluoroplastics of various sizes (micron particles, nanoparticles, and the like), each of which may be incorporated into the material alone or in combination by mechanical means or chemical treatment and / or polymerization. Known or developing technologies may be employed, such as those described in U.S. Patent Nos. 4,713,418 and 7,476,711 (each of which is incorporated herein by reference with respect to such technologies) and other technologies as described in U.S. Patent No. 7,019,083, which is also incorporated herein by reference with respect to the use of fluoroplastic particles. Suitable commercially available polymers are available from 3M Corporation, St. Paul, Minnesota.

[0152] Examples of other perfluoropolymers and elastomers formed therefrom using monomers at curing sites (such as those mentioned above) can also be found in U.S. Patent Nos. 6,518,366, 6,878,778 and U.S. Patent Publication No. 2008-0287627 and U.S. Patent No. 7,019,083, each of which is incorporated herein by reference to the perfluoropolymers described herein, the elastomers derived therefrom, and the methods of forming them.

[0153] Perfluoropolymers for use in the compositions claimed herein can be synthesized using any known or developing polymerization techniques to form fluorinated elastomers, including, for example, emulsion polymerization, latex polymerization, chain-initiated polymerization, batch polymerization, and others. Preferably, polymerization is carried out such that the reactive curing sites are located at one or both ends of the polymer backbone, and / or depending on the main polymer backbone.

[0154] Commercially available uncured (curable) perfluoropolymers include those sold under the name Dyneon™ by 3M Inc. in St. Paul, Minnesota, Daiel-Perfluor® from Daikin Industries, Ltd. in Osaka, Japan, and other similar polymers. Other preferred materials are also available from Solvay Solexis in Italy, SVLebedev Synthetic Rubber Research Institute, a federal unitary state-owned enterprise in St. Petersburg, Russia, Asahi Glass, and WL Gore in Japan. Other examples of suitable perfluoropolymers and blends thereof can be found, for example, in U.S. Patent Nos. 9,018,309 and 9,365,712, which are incorporated herein by reference.

[0155] When the uncured perfluoropolymer can be cured by any method (including radiation curing), it preferably includes at least one curing agent (also referred to herein as a crosslinking agent, curing agent and / or curing system) used with various curable fluoroelastomers and optionally used with the various curing sites described herein, and should be able to cure (i.e., be able to react and crosslink) or otherwise undergo curing reactions at the curing sites of the monomers or functional groups of the various uncured perfluoropolymers in the composition to form crosslinks, producing an elastomer material in the form of a molded article.

[0156] Preferred crosslinking or curing agents are used to form a crosslinking or curing agent with Crosslinking of compounds such as azoles, thiazoles, imidazoles, or triazine rings. In this invention, such compounds, as well as other curing agents including acetamipridime, tetramines, and aminehydrazones, can be used for crosslinking.

[0157] For nitrogen-containing curing sites, preferred curing agents are diphenyl-based curing agents and their derivatives, including diaminophenols and their salts and combinations thereof; diaminothiophenols, parabenzoquinone dioxime (PBQD), and salts of various such compounds can be used. Examples of suitable curing agents can be found, for example, in U.S. Patents 7,521,510 B2, 7,247,749 B2, and 7,514,506 B2, each of which is incorporated herein by reference in the relevant portion of a list of curing agents for cyano-containing perfluoropolymers. Alternatively, perfluoropolymers can be cured using radiation curing techniques.

[0158] A preferred curing agent for the curing site, having a cyano curing site, is a curing agent having an aromatic amine and at least two crosslinkable groups of formula (I) and (II) or a combination thereof, which, upon curing, form a benzimidazole crosslinked structure. Such curing agents are known in the art and are discussed in relevant portions and specific examples of U.S. Patent Nos. 6,878,778 and 6,855,774, the entire contents of which are incorporated herein by reference. R1 may be the same as or different from the groups according to formula (II) and may be NH2, NHR2, OH, SH, or a monovalent organic group or other organic group, such as alkyl, alkoxy, aryl, aryloxy, aralkyl, and arylalkoxy groups having about 1 to about 10 carbon atoms, wherein such non-aryl groups may be branched or straight-chain and substituted or unsubstituted, and R2 may be -NH2, -OH, -SH, or a monovalent or other organic group, such as aliphatic hydrocarbon, phenyl, and benzyl, or alkyl, alkoxy, aryl, aryloxy, aralkyl, and arylalkoxy groups having about 1 to about 10 carbon atoms, wherein the non-aryl groups may be branched or straight-chain and substituted or unsubstituted. Preferred monovalent or other organic groups, such as alkyl and alkoxy groups (or their perfluorinated forms), have 1 to 6 carbon atoms, and preferred aryl groups are phenyl and benzyl. Examples include -CF3, -C2F5, -CH2F, -CH2CF3 or -CH2C2F5, phenyl, benzyl; or phenyl or benzyl groups in which one to five hydrogen atoms are substituted with fluorine atoms, such as -C6F5, -CH2C6F5, wherein the group may be further substituted with -CF3 or other low-carbon perfluoroalkyl groups; or phenyl or benzyl groups in which one to five hydrogen atoms are substituted with CF3, such as, for example, C6H5-n(CF3)n, -CH2C6H5-n(CF3)n (where n is 1 to to 5). Hydrogen atoms may be further substituted with phenyl or benzyl groups. However, phenyl and CH3 groups preferably provide excellent heat resistance, good crosslinking reactivity and relatively easy synthesis.

[0159] The structure of formula (I) or formula (II) incorporated into an organic amine shall include at least two such groups of formula (I) or formula (II) to provide at least two crosslinking reactive groups.

[0160] This article may also use curing agents with the following formulas (III), (IV) and (V). R3 is preferably an SO, O, or CO or an organic or alkyl group, such as an alkyl, alkoxy, aryl, aralkyl, or aralkyloxy group with one to six carbon atoms, or a perfluorinated form of such a group having about one to about ten carbon atoms, and is branched or straight-chain, saturated or unsaturated, and branched or straight-chain (for non-aryl groups) or a single bond. R4 is preferably a reactive side group, such as those listed below: ; Wherein Rf1 is a perfluoroalkyl or perfluoroalkoxy group of about 1 to about 10 carbon atoms, which may be a straight-chain or branched-chain group and / or saturated or unsaturated and / or substituted or unsubstituted; and Where n is an integer from approximately 1 to approximately 10.

[0161] The choice of a single curing agent or a combination thereof depends on the curing sites to be crosslinked and is selected from all curing agents described herein that fall within the scope of this invention. Regarding heat resistance, the crosslinking agent... Zyrazole-, imidazole-, thiazole-, and triazine-rings are preferred, and may include compounds listed below and further discussed in relation to formulas (I), (II), (III), (IV), and (V), specifically, formula (II), where R1 is the same or different and is -NH2, -NHR2, -OH, or -SH, where R2 is a monovalent organic group, preferably not hydrogen; formula (III), where R3 is -SO2-, -O-, -CO-, and an alkylene group of 1 to 6 carbon atoms, a perfluoroalkylene group of 1 to 10 carbon atoms, or a single bond, and R4 is indicated below; formula (IV), where Rf1 is a perfluoroalkylene group of 1 to 10 carbon atoms; and formula (V), where n is an integer from 1 to 10. Among such compounds, the heat resistance of the compound of formula (II) as indicated herein is preferred, which is improved after crosslinking due to the stabilization of the aromatic ring. Regarding R1 in formula (II), it is also preferable to use -NHR2 as R1, because the NR2 bond (where R2 is a monovalent organic group and not hydrogen) has higher antioxidant properties than the NH bond.

[0162] A compound having at least two groups as in formula (II) is preferred and having two to three crosslinkable reactive groups, more preferably having two crosslinkable groups.

[0163] The exemplary curing agents based on the preferred formulations described above include at least two functional groups, such as those with the following structural formulas (VI), (VII), or (VIII): R5 represents a saturated or unsaturated, branched or straight-chain, substituted or unsubstituted group, such as alkyl, alkoxy, aryl, SO, O, CO, or a similar group that is perfluorinated relative to a carbon atom and preferably has about 1 to about 10 carbon atoms; R1 is as defined elsewhere in this document and R6 may be O, SO2, CO or a perfluorinated organic group, such as alkyl, alkoxy, aryl, aryloxy, aralkyl and arylalkoxy having about 1 to about 10 carbon atoms, wherein such non-aryl groups may be branched or straight and substituted or unsubstituted, or be single or extended alkyl bonds.

[0164] From the viewpoint of ease of synthesis, in another preferred specific example of this paper, the best crosslinking agent is a compound having two crosslinkable reactive groups as represented by formula (II), which are shown below in formula (VIII). Where R1 is as described above and R6 is -SO2, -O-, -CO-, an alkyl group of 1 to 6 carbon atoms, a perfluoroalkyl group of 1 to 10 carbon atoms, a single bond, or a group as shown in formula (IX): This formula provides an easier synthesis. Preferred examples of alkyl groups with 1 to 6 carbon atoms are methylene, ethyl, propyl, butyl, pentyl, hexyl, and similar groups. Examples of perfluoroalkyl groups with 1 to 10 carbon atoms are... and similar groups. Examples of such compounds are known to be diaminophenyl compounds. Preferred compounds based on this structure include compounds of formula (X): R7 may be the same or different in each case, and each R7 is hydrogen, an alkyl group having 1 to 10 carbon atoms; a partially fluorinated or perfluorinated alkyl group having 1 to 10 carbon atoms; a phenyl group; a benzyl group; or a phenyl or benzyl group in which 1 to 5 hydrogen atoms have been replaced by fluorine or a low-carbon alkyl or perfluorinated alkyl group (such as CF3).

[0165] Unrestricted examples of curing agents include 2,2-bis(2,4-diaminophenyl)hexafluoropropane, 2,2-bis[3-amino-4-(N-methylamino)phenyl]hexafluoropropane, 2,2-bis[3-amino-4-(N-ethylamino)phenyl]hexafluoropropane, 2,2-bis[3-amino-4-(N-propylamino)phenyl]hexafluoropropane, 2,2-bis[3-amino-4-(N-phenylamino)phenyl]hexafluoropropane, 2,2-bis[3-amino-4-(N-perfluorophenylamino)phenyl]hexafluoropropane, 2,2-bis[3-amino-4-(N-perfluorophenylamino)phenyl]hexafluoropropane, and similar compounds. Among these, 2,2-bis[3-amino-4-(N-methylamino)phenyl]hexafluoropropane, 2,2-bis[3-amino-4-(N-ethylamino)phenyl]hexafluoropropane, 2,2-bis[3-amino-4-(N-propylamino)phenyl]hexafluoropropane, and 2,2-bis[3-amino-4-(N-anilino)phenyl]hexafluoropropane are preferred for their superior heat resistance properties. Tetraamines, such as 4,4'-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis[N1-phenyl-1,2-phenylenediamine] or more preferably 2,2-bis[3-amino-4-(N-anilinophenyl)]hexafluoropropane, are also preferred for their superior heat resistance properties.

[0166] Other suitable curing agents include those known or yet to be developed in this technology. Curing agents, amine oximes, and amine hydrazones forming azole-, imidazole-, thiazole-, and triazine-rings, and especially diamine phenol, diamine phenol AF, and combinations thereof; diamine thiophenol; diamidinium; diamine oxime; diamine hydrazone; monoamidinium; monoamine oxime and monoamine hydrazone, examples of which are listed, for example, in U.S. Patent Nos. 7,247,749 and 7,521,510, the relevant portions of which are incorporated herein by reference, including curing agents, co-curing agents, and accelerators. Diamine oximes, diamine hydrazones, diamine phenol, diamine thiophenol, or diamine phenol curing agents are preferred herein for reacting with nitrile or cyano groups, carboxyl groups, and / or alkoxycarbonyl groups in a perfluoropolymer to form the preferred perfluoroelastomers in some specific examples herein, which elastomers have a cross-linked form in the cured articles formed from the compositions herein. Azole ring, thiazole ring, imidazole ring, or triazine ring.

[0167] In one specific example herein, compounds comprising at least two chemical groups having crosslinking reactive groups as in formula (I) or (II) may be used to improve heat resistance and stabilize aromatic ring systems. For groups having two to three such groups in (I) or (II), it is preferable to have at least two in each group (I) or (II), as fewer groups may not provide sufficient crosslinking. Such combinations are known to us and described in the applicant's U.S. Patent Nos. 9,018,309 B2 and 9,365,712 B2, which are incorporated herein by reference in their respective parts.

[0168] Such compositions are preferably blends of a first curable perfluoropolymer and a second curable perfluoropolymer having a ratio range of about 95:5 to about 5:95, more preferably about 80:20 to about 20:80, and even more preferably about 40:60 to about 60:40 or about 50:50. Each of at least one curing site monomer in each curable perfluoropolymer is preferably present in an amount of about 0.1 to about 10 moles and is individually present in each of the curable perfluoropolymers used in any blended composition.

[0169] When at least one curing agent is used, it can be adapted to cure different amounts of the curable perfluoropolymer curing site monomers present in the composition, for example, in a total amount of about 0.2 parts by weight to about 10 parts by weight of at least one curable perfluoropolymer per 100 parts by weight in the composition, and each may be present in the composition in an amount of about 0.1 to about 6 parts by weight of per 100 parts by weight of the perfluoropolymer, or preferably in an amount of about 0.1 to about 2 parts by weight of per 100 parts by weight of the perfluoropolymer. In one specific example, at least two curing agents are used in the first perfluoropolymer in an amount of about 0.5 to about 4 parts by weight of the first curing agent and about 0.3 to about 2 parts by weight of the at least one second curing agent.

[0170] In the blend, at least one curing site of any or both of the curable perfluoropolymers may be a nitrogen-containing curing site. At least one curing site of the monomer in the first curable perfluoropolymer may be selected from a group consisting of cyano, carboxyl, carbonyl, alkoxycarbonyl, and combinations thereof, with cyano being the most preferred.

[0171] At least one curing agent is preferably one of the following suitable curing agents: fluorinated imine acetamidine; diamine phenol; diamine; diamine oxime; diamine hydrazone; monoamidine; monoamine oxime; monoamine hydrazone; diamine thiophenol; diamine phenol; tetraamine and aromatic amine, having at least two crosslinkable groups represented by formula (II): Where R1 may be the same or different and each is -NH2, -NHR2, -OH or -SH; R2 is a monovalent organic group; Compounds represented by formula (III): Where R3 is -SO2-, -O-, -CO-, an alkyl group having 1 to 6 carbon atoms, a perfluoroalkyl group having 1 to 10 carbon atoms, or a single bond, and R4 is ; Compounds represented by formula (IV): Where Rf1 is a perfluoroalkyl group having 1 to 10 carbon atoms; compounds represented by formula (V): Where n is an integer from 1 to 10; and combinations thereof, wherein at least one curing agent is capable of reacting with at least one curing site in at least one first perfluoropolymer and at least one curing site in at least one second perfluoropolymer to crosslink at least one perfluoropolymer and at least one second perfluoropolymer in the composition.

[0172] At least one curing agent is preferably an aromatic amine having at least two crosslinkable groups represented by formula (II), wherein R1 is -NHR2; fluorinated imine acetamidine; diamine phenol; and combinations thereof.

[0173] In one specific example, the curable fluoroelastomer composition includes at least one curing agent in the form of a compound, preferably a tetraamine compound within the range of compounds indicated above. Such compounds can be used alone or in combination. The preferred compound used herein as a curing agent is the compound according to formula (II), wherein R1 is -NHR2 and R2 is aryl. Such compounds are also referred to as 4,4'-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bis[N1-phenyl-1,2-phenylenediamine] ("Nph-AF") (also referred to as "V6"). (XI)

[0174] In another specific example herein, the curing agent that may be used includes perfluoroimino acetamidine, such as those found in U.S. Patent No. 8,362,167, which is incorporated herein by reference in the relevant portion relating to the following compounds and similar compounds. A preferred compound, also described as DPIA-65, is shown below. (XII), Other preferred compounds are diamine phenol and its salts, as well as combinations of the material with other curing agents.

[0175] In one specific example, the composition may be a perfluoroelastomer composition and at least one curing agent may include Nph-AF (or V6): (XI). This compound can be used alone or in combination with another curing agent (such as in combination with or as an alternative to bisamine phenol or bisamine phenol AF), wherein at least one curing agent may further comprise DPIA-65: (XII).

[0176] In other preferred embodiments described herein, the compound of formula (XII) is used alone or in combination with the following Each R1 is independently -NH2, -NHR2, -OH, or -SH; R2 is a monovalent organic group; and R6 is -SO2, -O-, -CO-, an alkyl group having 1 to about 6 carbon atoms, a perfluoroalkyl group having 1 to about 10 carbon atoms, a single bond, or a group shown in formula (IX): . The second curing agent in this type of combination is preferably a compound according to formula (X): R7 is independently selected from hydrogen, an alkyl group having 1 to about 10 carbon atoms; a partially fluorinated or perfluorinated alkyl group having 1 to 10 carbon atoms; a phenyl group; a benzyl group; or a fluorinated or partially fluorinated phenyl group; a fluorinated or partially fluorinated benzyl group; or a phenyl or alkyl group having one or more functional groups of a low carbon number alkyl or perfluoroalkyl group. The second curing agent in the combination is preferably a diamine phenol and its salt or a combination thereof.

[0177] In another specific example, the preferred ratio of the curing agent type represented by Formula XII to the bisamine phenol type curing agent or related compound is preferably about 0.5:1 to about 35:1, preferably about 1:1 to about 32:1 and most preferably about 2:1 to 15:1.

[0178] A curable perfluoroelastomer composition for use with the carbon nanostructures mentioned above herein comprises a curable perfluoropolymer containing tetrafluoroethylene, a first perfluoroalkyl vinyl ether, and at least one first curing site monomer having at least one curing site, or, in another specific example, a monomer having at least two curing sites, wherein the tetrafluoroethylene and the second perfluoroalkyl vinyl ether are present in varying amounts in the curable perfluoropolymer. At least one second curing site monomer having at least one curing site may also be used. Another additional curable perfluoropolymer may also be used.

[0179] The carbon nanostructure additives used herein may be incorporated into the polymer blend before or after blending and before or after incorporating any other fillers or additives. However, it is preferred that, when using blended polymers, the polymer is blended before the introduction of the additives or fillers and / or the carbon nanostructure additives herein. It is also preferred that any curing agent is introduced after other fillers and additives (including carbon nanostructure additives) and before curing to avoid premature initiation of curing.

[0180] In addition to the curing agents described herein used with fluorinated curable perfluoropolymers having nitrile groups and similar groups, the use of curing agents known in the art to cure nitrile groups for at least one curable perfluoropolymer and / or for other perfluoropolymers added to the compositions herein is within the scope of this invention. Preferred examples of other curing agents known in the art include those capable of forming triazine rings. If a halogenated curing site is employed, peroxide curing agents and co-curing agents well known in the art may also be used. Other suitable curing agents may include those listed above.

[0181] Additives that can be incorporated into curable fluoropolymers and perfluoropolymer compositions, blends, and copolymers, in addition to curing agents and carbon nanostructure additives mentioned herein, although not necessary, include one or more curing accelerators, co-curing agents, auxiliaries, processing aids, plasticizers, fillers such as silicon dioxide (unless it affects conductivity), fluoropolymers as mentioned above (such as TFE), fluorinated copolymers, core-shell modified fluoropolymers and similar substances in the form of powders, aggregates, fibers, and nanoparticles, fluorinated graphite (the amount of which does not affect the desired final effect or conductivity), barium sulfate, non-conductive, low-conductive, or dielectric carbon black or fluorinated carbon, clay, talc, and metallic fillers (such as titanium oxide, alumina, yttrium oxide, and silicon oxide). Zirconia (especially for EMI / RFI applications in environments where the metal material is not problematic), metal carbides (silicon carbide, aluminum carbide), metal nitrides (silicon nitride, aluminum nitride), other inorganic fillers (aluminum fluoride, carbon fluoride), colorants, organic dyes and / or pigments, such as azo, isoindolineone, quinacridone, diketopyrrolopyrrole, anthraquinone and the like, aceimine fillers (such as polyaceimide, poly(acetamide aceimide) and polyether aceimide), ketone plastics (such as polyaryl ketones, such as PEEK, PEK and PEKK), polyarylates, polyurethane, polyether urethane, polyphenylene sulfide, polyoxybenzoic acid and the like, which may be used in amounts known in this art and / or varied for different properties. All fillers mentioned herein may be used alone or in combination of two or more such fillers and additives.

[0182] Preferably, any additive in at least one curing agent (including any curing accelerator, co-curing agent, adjuvant and the like) capable of curing one or more curing site monomers is added after other fillers, additives and / or carbon nanostructure additives (e.g. aggregates) are incorporated into the fluoro or perfluoropolymer and after their network is formed in the curable polymer during mixing or blending.

[0183] The components and articles formed for the final application, especially those for EMI and RFI shielding, may be highly filled with carbon nanostructure additives as needed. The fillers selected as appropriate, such as those mentioned above, may be used in a total of up to about 100 parts or even up to 300 parts per 100 parts of at least one curable polymer in the composition, and may be more or less, as further described below.

[0184] After combining the curable polymer with carbon nanostructure additives and / or any other additives (including any curing agents and related additives, if present) as appropriate, the curable polymer in the fluoroelastomer or perfluoroelastomer composition is cured to form a cured fluoroelastomer or perfluoroelastomer article as described herein.

[0185] The curable composition is preferably cured at the temperature and time conventionally used to form the desired crosslinking, depending on the curing method or system, curing site, and / or the selected curing agent. The temperature should be sufficient to allow the curing reaction to proceed until the curable fluoropolymer or perfluoropolymer in the composition is substantially cured, preferably at least 90% cured or higher. Preferred curing temperatures and times for the preferred curable fluoropolymer and / or perfluoropolymer compositions will depend on the polymer, but may be, for example, from about 150°C to about 250°C for about 5 to about 40 minutes. After curing, a post-curing step may be used, if applicable. Examples of suitable post-curing temperatures and times for the preferred perfluoropolymers mentioned herein are, for example, from about 200°C to about 360°C for about 5 to about 48 hours.

[0186] During curing, the curable components described herein can be formed into a molded article while being cured using heat and pressure applied to a mold. Preferably, the combined curable fluoropolymer and perfluoropolymer are formed into a preform, such as an extruded rope or other available shape, for inclusion in a mold having a recess shaped to receive the preform and for forming a molded article during curing. Post-curing may also be preferably carried out in air or an inert gas (e.g., nitrogen), where applicable.

[0187] Other curing agents and curing accelerators that act together with or accelerate the curing of fluoropolymers or perfluoropolymers, or accelerate the curing of any other curable polymers selected as appropriate, may also be included herein. Non-curable fluoropolymers or perfluoropolymers include those lacking reactive curing sites and formed from one or more olefinic unsaturated monomers (such as TFE, HFP, and PAVE). Other curable perfluoropolymers may be any of the curable perfluoropolymers indicated herein, as well as those having curing sites known in the art suitable for crosslinking with organic peroxide curing systems, diamine phenyl-based curables, and the like. Such polymers may be added to develop alternative blends and to modulate the properties of the compositions indicated herein.

[0188] In addition to using carbon nanostructures in the elastomeric matrices mentioned above, various polymer matrices suitable for forming components and assemblies (including hard seals, such as certain gaskets) can be used in any of the QTC or EFI and / or RFI shielding end applications. However, it is preferable to incorporate the carbon nanostructure additives described herein into the elastomeric matrices indicated above. Polymers suitable as a primary matrix component (such as in QTC end applications, for example, for forming self-sensing compressible gaskets or medical components or assemblies) can be various homopolymers, copolymers, or blends, or blends of such polymers. Preferred polymers are those known to be suitable for use with conductive fillers or additives, and may include thermoplastics.

[0189] Examples of suitable matrix polymers include polyarylene polymers (polyetherketone, polyetheretherketone, polyetherketoneketone and the like), thermoplastic melt-processable fluoropolymers (such as hexafluoropropylene-perfluoroalkyl vinyl ether copolymers and fluorinated ethylene-propylene polymers), polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, chlorinated fluoropolymers, silicone polymers and non-curable fluoropolymers and perfluoropolymers, polyolefins such as polyethylene, polypropylene (including high-density and low-density forms of such polyolefins), polyethylene terephthalate, polysiloxane, polyurethane, aromatic polyamine, polyamine, polyimide, polyetherimide, polyphenylene sulfide, polyphenylene oxide, polyether oxide, polyamide imide, polybenzimidazole, polycarbonate, polyacrylonitrile-butadiene-styrene, polybutadiene-styrene, polyepoxides and the like, as well as blends, copolymers, admixtures and other combinations thereof.

[0190] In the compositions and various final components and applications described herein, carbon nanostructure additives are incorporated into the polymers or curable polymers described above to form articles. The carbon nanostructures may be combined with other known QTC or EMI and / or RFI shielding additives or other suitable additives for the desired final application, or with the selected matrix polymers mentioned above. In certain specific examples herein, such three-dimensional, branched, and / or cross-linked carbon nanostructure additives may be combined with other standard conductive fillers, such as carbon powder, flake, or fiber fillers; gold-plated glass, gold-plated particles of other metals (such as nickel, aluminum, or copper) or polymer fillers, nickel-coated graphite, graphene, graphite, carbon black, graphene derivatives, standard single-walled or multi-walled carbon nanotubes, gold, silver, nickel, copper, and combinations or mixtures thereof. Such additional conductive additives may be present in amounts of about 0.25 parts by weight to about 100 parts by weight per 100 parts by weight of the matrix polymer, provided that no conductive filler is present in an amount that would unnecessarily hinder or otherwise materially affect the beneficial properties of the carbon nanostructure in the polymer and curable polymer for their intended end application.

[0191] The invention will now be described with reference to the following non-limiting examples. Example 1

[0192] In this embodiment, the formulation is prepared for use in EMF or RFI shielding end applications. The composition prepared according to the invention is compared with industry standards for these specific end applications, incorporating a fluorosilicone matrix and nickel-coated graphite filler. Such materials are inexpensive as base polymers and can withstand high loading, making them standard products for these end applications. This material is available as Stockwell 80, a commercial product from Stockwell Elastomerics. This material and different samples formed as O-rings are tested in a 214 sample size. Some are bonded to aluminum discs. Samples are mounted in small valves modified for heating. The valves are circulated at a rate of 1 cycle / 2 seconds. Test samples are loaded into the valves and heated. Clean, filtered air is drawn through the valves and fed into the particle counter during circulation. Particle counts are collected throughout the test.

[0193] In this embodiment, comparative samples with Stockwell 80 fluorosilicone (FMVQ) and nickel-graphite filler were used, as well as samples 1-7 prepared using fluoroelastomer (FKM) and perfluoroelastomer (FFKM) compositions. In the perfluoroelastomer compositions, the Lodestar PFK-300 polymer was included in a composition containing 40 parts of Cabot® CNS aggregates per 100 parts of curable polymer. These aggregates were three-dimensional branched carbon nanostructures with interconnecting tubes. The composition also included 1.6 parts of bis(aminophenol) curing agent and 3 parts of Fomblin® oil per 100 parts of curable polymer for treatment. The fluoroelastomer compositions used included 100 parts of Tecnoflon™ FOR 801HS as the curable polymer, 50 parts of the same Cabot carbon nanostructure additive, and 9 parts by weight of Electromag™ 170, each based on 100 parts by weight of the curable polymer. The test composition was determined according to Table 1, and the micronization results are shown in Figure 1. Table 1 Sample number elastomer type temperature Comparison Samples FVMQ sealing gasket 200℃ 1 FFKM Joint seal 250℃ 2 FFKM Joint seal 250℃ 3 FFKM Joint seal 250℃ 4 FKM Joint seal 250℃ 5 FFKM Seals 250℃ 6 FFKM Seals 200℃ 7 FFKM Seals 200℃

[0194] The filtered comparison samples obtained good resistivity as expected for their commercial end use, with a continuous release of a count of particles as shown over time. In each of the test samples, initial surface or filtration release occurred, followed by a rapid decrease in particle size over time to a significantly low level. The particle size levels of the present invention's samples were significantly lower in use compared to commercially available standards.

[0195] Other compounds were formed using the fluoroelastomer FKM as described above, varying amounts of Cabot carbon nanostructure additives, and varying amounts of Fomblin® oil, as shown below, using the initial compositions in Table 2. Sample 4 served as a control in this test, exhibiting volume resistivity in ohms-cm at a 20 lbs. load. As can be seen, compared to commercially acceptable current state-of-the-art samples, the sample according to the invention not only produces substantially lower microparticle size but also provides excellent conductivity and exhibits a volume resistivity level below 0.5 ohms-cm. This data is shown in Table 2 below. Table 2 Components / Sample Number 8 9 10 11 12 4 FOR 801 HS 100 100 100 100 100 100 CNS aggregates 70 70 40 40 55 50 Fomblin M60 0 6 0 6 3 0 Elastomag 170 9 9 9 9 9 9 Volume resistivity (ohm-cm) 0.33 0.46 1.72 1.79 0.82 0.88 Example 2

[0196] In this embodiment, a composition according to the invention exhibiting properties conforming to those used in QTC elastomer composites was prepared. The composition was formed using Tecnoflon® VPL X75545 fluoroelastomer, i.e., peroxide-curable FKM. The same Cabot carbon nanostructure in aggregated form used in Example 1 was incorporated at different weight levels based on 100 parts by weight of the Tecnoflon® base polymer. A peroxide curing system was also included, comprising Varox® DBPH-50 peroxide curing agent and triallylisocyanurate (TAIC) DLC co-curing agent as curing agent additives. Additional fillers included Austin Black 325 (suitable for processable, non-conductive carbon fillers due to its plate-like structure) and low-level thermally conductive carbon black N-990 from Cancarb, available as Thermax®. Due to the size of the fillers, the Thermax® additives do not impede the networking and interconnection of the carbon nanostructure.

[0197] The characteristics, physical properties, and formulations of test samples 13-21 are shown in Table 3 below. Table 3 Components (phr) 13 14 15 16 17 18 19 20 twenty one Tecnoflon VPL X 75545(FKM) 100 100 100 100 100 100 100 100 100 N-990 Black 5 5 5 5 5 5 5 5 5 Austin Black 325 3 3 3 3 3 3 3 3 3 Cabot carbon nanostructure 4.8 6 7.2 8.4 9.6 4.8 4 4.25 4.5 TAIC DLC 5 5 5 5 5 5 5 5 5 Varox DBPH-50 2 2 2 2 2 2 2 2 2 physical properties Sample number 12 13 14 15 16 17 18 19 20 Tensile strength, psi 2149 2602 2859 2925 2962 1900 1847 1863 1935 Elongation, % 136 110 80 77 63 148 158 143 154 Modulus at 100%, psi 1847 2538 NA NA NA 1556 1460 1522 1535 Modulus at 50%, psi 1104 1662 2168 2378 2608 889 843 882 844 proportion 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 Type A hardness, pts 75.8 79.4 83.2 85.2 85.4 76.3 76.0 74.6 75.9 M-type hardness, pts 79.1 84.0 86.6 88.1 90.5 81.2 78.8 81.8 81.5 Compression deformation % 12 13 14 15 16 17 18 19 20 25% deflection over 70 hours at 392℉ / 200℃ (average) 36.76 41.18 45.59 48.53 51.43 40.00 38.57 38.57 44.29

[0198] Initial screening tests on samples containing 0–4.8 parts by weight of carbon nanostructure additive per 100 parts by weight of curable polymer showed that a level of at least approximately 4.8 parts by weight of carbon nanostructure additive in the formulation provided sufficient quantity for measuring volume resistivity. Further testing was conducted using samples 12–20 in the form of O-rings and buttons, where the carbon nanostructure additive was present at an amount of 4.8 to 9.6 parts by weight per 100 parts by weight of curable polymer. Volume resistivity was measured using a Ketihley 2410 probe with a through-surface and 4-point probe method.

[0199] As shown in Figure 2, for samples 13-17 without load, the volume resistivity decreased with increasing carbon nanostructure additive content. Once a load was applied, the QTC effect became significant. When a 5% deflection was applied, as also shown in Figure 2, the volume resistivity of sample 13 with 4.8 parts by weight of the additive decreased by 4.5 times. Similar trends were observed for the four samples 14 to 17.

[0200] Referring to samples 18 to 21 and Figure 3, the optimal QTC effect is achieved by this formulation at a content of 4.25 to 4.5 parts by weight of carbon nanostructure additive per 100 parts by weight of curable polymer. This effect is applicable in semiconductor valves as a measure of resistance and compressive deformation that varies with resistance in evaluating seal erosion. These characteristics are shown in Figure 3 for samples 18 to 21. Sample 18 is the same formulation as sample 13, but was prepared and tested separately from samples 19-21.

[0201] When testing the buttons, and referring to Figure 4, test button samples 22-26, which are made from the components of samples 13-17, show that when the carbon nanostructure additive is increased by a factor of two from 4.8 parts to 9.6 parts, the volume resistivity decreases. At a constant level of carbon nanostructure additive, the volume resistivity initially decreases as the deflection increases from 5% to 10%. When the deflection increases beyond 10%, the volume resistivity increases. Example 3

[0202] In this embodiment, sample KF seals were prepared using a compound formulation with carbon nanostructure additives according to the present invention. The seals were manufactured to ISO 40 size according to ISO standard 2861-1 (referred to herein as "KF-40" seals). These seals underwent conductivity testing.

[0203] The QTC formulations listed in Table 4 were prepared and tested to identify the preferred composite formulations for preparing KF-40 composite seals. As in Example 1, PFK-300 from Lodestar was used to form the composition; this is a curable perfluoroelastomer polymer cured in this example using a bis(aminophenol) (BOAP) curing agent. The aggregated Cabot carbon nanostructures used in Examples 1 and 2 above were incorporated at different levels in this example, ranging from parts by weight of 100 parts by weight of the PFK-300 base polymer. The additional fillers used in the five samples prepared prior to this (samples 27, 28, 29, 30 and 31) included 3 parts per hundred parts Austin Black 325 used in Example 2 (a non-conductive carbon filler suitable for processability due to its plate-like structure) and 5 parts per hundred parts thermally conductive carbon black N-990 from Cancarb available as Thermax®, which, due to its particle size, can be used without hindering the networking and interconnection of carbon nanostructures within the cured polymer matrix.

[0204] The remaining samples (samples 32-40) were formed in the same manner as samples 27-31, but without Austin Black 325 or Thermax® N-990 additives. In fact, the only filler was a mixture of 4 to 12 parts of Cabot carbon nanostructured aggregates per 100 parts of the base polymer PFK-300. Table 4 Components (phr) 27 28 29 30 31 32 33 34 35 36 37 38 39 40 PFK-300 100 100 100 100 100 100 100 100 100 100 100 100 100 100 N-990 Black 5 5 5 5 5 -- -- -- -- -- -- -- -- -- Austin Black 325 3 3 3 3 3 -- -- -- -- -- -- -- -- -- Cabot carbon nanostructure 4 6 8 10 12 1 3 5 7 9 8 10 12 14 BOAP 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2

[0205] Samples 32-40 were prepared by initially weighing the required components separately in a container. The mill and mixer were preheated to 80℉. The PFK-300 base polymer was passed through the mill to produce flakes. BOAP (2,2-bis[3-amino-4-hydroxyphenyl]hexafluoropropane, also known as diamino-bisphenol AF) was added to the container containing the Cabot carbon nanostructure and stirred until the two components were fully mixed. The mixture of BOAP and carbon nanostructure was slowly added to the top of the polymer film flakes while the mixer was rotated at 15 RPM. All components were then mixed for 2 minutes or until the mixture temperature reached 160℉. The batch was then dripped from the mixer and flaked under clamping on the mill. The mixture was cut and re-blended on the mill for 1 minute, and this cutting and blending was repeated 5 times. After the 5th cycle, the material was flaked again. After aging for 12 hours, the flakes were passed through the mill twice more and then removed. Approximately five sample KF-40 seals were fabricated from the thin sheets and tested using a click-and-die process, in which the material was cut using an ID / OD die. The die-cut material was then cut to a certain length and encased in a compression mold.

[0206] Conductivity / resistivity was measured using a four-point probe array as illustrated in Figure 5. Compression was applied to samples 29-31 and 37-40 from 0% to 30%, as shown in Figures 6, 7, and 8. Figure 6 shows the conductivity behavior of samples 29-31 with 8, 10, and 12 parts per hundred of all three fillers at different levels of carbon nanostructure. Conductivity deflects at approximately 10% compression and then tends to level off. Figure 7 shows the samples with only 8, 10, 12, and 14 parts per hundred of carbon nanostructure additives; larger conductivity jumps are observed in the more heavily loaded samples, but conductivity increases between 5% and 15% compression for all samples before stabilizing. However, the smaller the value, the smaller the effect of conductivity variation. Figure 8 shows a comparative behavior between samples with carbon black filler and carbon nanostructure from samples 29-31 and samples with only carbon nanostructure from samples 37-40.

[0207] In all samples, a similar pattern was observed in which conductivity increased with deflection and then tended to equilibrium, indicating that the samples experienced the QTC recombination effect under suppression.

[0208] Alternatively, the KF-40 seal used for testing can also be made by extruding material using a 210 O-ring cross-section.

[0209] To utilize the components in QTC smart seals, seals configured using the components described herein (such as those in Example 3 above) can be connected to circuitry, for example, a resistance measurement circuit, to capture changes in the seal's conductivity under compression. This data can be transmitted using any suitable method (hardwired or via wireless communication). An example of a resistance system is shown in Figure 9 for use with a four-point probe configuration, where four leads are connected and the resistance is transmitted to a resistance measurement system via this system. This system can be further connected using a small printed circuit board (PCB) that communicates with the resistance measured on the seal, and LEDs can be used to indicate when proper compression is achieved during installation.

[0210] Those skilled in the art will understand that modifications can be made to the specific examples described above without departing from the broader inventive concept of this invention. Therefore, it should be understood that this invention is not limited to the specific examples disclosed, but is intended to cover modifications within the spirit and scope of the invention as defined in the appended claims.

[0211] none

Claims

1. A composition for forming an article comprising: at least one matrix polymer having at least one curable polymer having at least one functional group for crosslinking, and a three-dimensional, branched and / or crosslinked carbon nanostructure additive provided in an amount of 1 to 30 parts by weight of the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer, wherein after crosslinking the matrix polymer and after forming an elastic article from the composition, the article (1) is an insulator when not subjected to compressive stress and is conductive when subjected to compressive stress, and / or (2) the conductivity level of the article under compressive stress differs from the conductivity level of the article when not subjected to compressive stress, such that the article exhibits one or more of a dissipative effect and a quantum tunneling recombination effect, and the article exhibits a change in conductivity level under compressive stress when used for immediate determination and evaluation of the performance of the article.

2. The composition of claim 1, comprising 1 to 15 parts by weight of the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer.

3. The composition of claim 1, wherein when the article is formed from the composition, the article has a quantum tunneling effect, and wherein the composition comprises at least 2 parts by weight of the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer.

4. The composition of claim 3, wherein the composition comprises at least 3 parts by weight of the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer.

5. The composition of claim 4, wherein the composition comprises at least 4 parts by weight of the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer.

6. The composition of claim 5, wherein the composition comprises 4 to 20 parts by weight of the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer.

7. The composition of claim 6, wherein the composition comprises 4 to 15 parts by weight of the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer.

8. The composition of claim 1 further comprises at least one conductive filler different from the carbon nanostructure additive, the conductive filler being selected from the group consisting of powder, flake and fiber fillers, comprising one or more of the following: carbon, metallized glass, metallized particles, wherein the particles comprise metal or polymer, nickel-coated graphite, graphene, graphite, carbon black, graphene derivatives, single-walled carbon nanotubes, multi-walled carbon nanotubes, gold, silver, nickel, copper and combinations or mixtures thereof.

9. The composition of claim 8, wherein the composition comprises 0.25 to 100 parts by weight of the at least one conductive filler different from the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer.

10. The composition of claim 1, wherein the composition comprises at least one crosslinking additive for reacting with the at least one functional group when crosslinking is performed to form the article.

11. An article formed from the components as claimed in claim 1.

12. The article of claim 11, wherein the article is an elastic quantum tunneling compound and is selected from the group consisting of other components in a seal, gasket or sealing assembly.

13. The article of claim 11, wherein the article is an elastic quantum tunneling composite and a self-sensing article, and wherein when the article is electrically connected to a circuit and a voltage is applied, the change in conductivity of the article when the article is in use and subjected to compressive stress is measured, and the change in conductivity is used to determine and evaluate the performance of the article in real time.

14. A method of manufacturing an article comprising providing a composition comprising at least one matrix polymer having at least one curable polymer having at least one functional group for crosslinking, and the composition comprising at least one three-dimensional, branched and crosslinked carbon nanostructure additive, wherein the at least one carbon nanostructure additive is present in an amount of at least 1 part by weight to 30 parts by weight per 100 parts by weight of the at least one matrix polymer; and forming an elastic article from the composition by curing and thermoforming, wherein (1) the article is an insulator when not subjected to compressive stress and is conductive when subjected to compressive stress, and / or (2) the conductivity level of the article under compressive stress is different from the conductivity level of the article when not subjected to compressive stress, such that the article exhibits at least one of dissipative effect or quantum tunneling effect, and the article has a change in conductivity level under compressive stress when used for real-time measurement and evaluation of the performance of the article.

15. The method of claim 14, wherein the article is a seal, gasket, or other component of a sealing assembly.

16. The method of claim 14, wherein the composition comprises at least one crosslinking additive for reacting with the at least one functional group for crosslinking.

17. The method of claim 14, wherein the article is an elastic quantum tunneling composite.

18. The method of claim 14, wherein the conductivity level of the article under compressive stress is higher than the conductivity level of the article when not under compressive stress.

19. The method of claim 14, wherein the article is an elastic quantum tunneling composite and a self-sensing article, and wherein when the article is electrically connected to a circuit and a voltage is applied, the change in conductivity of the article when the article is in use and subjected to compressive stress is measured, and the change in conductivity is used to determine and evaluate the performance of the article in real time.

20. A method of manufacturing an article comprising providing a composition comprising at least one matrix polymer, the matrix polymer comprising at least one curable polymer having at least one functional group for crosslinking, and the composition comprising at least one three-dimensional, branched, and crosslinked carbon nanostructure additive, wherein the curable polymer is selected from the group consisting of curable fluoropolymers, curable perfluoropolyethers, and curable perfluoropolymers and blends and copolymers thereof, and wherein the at least one carbon nanostructure additive is present in an amount of at least one part by weight per 100 parts by weight of the at least one The composition comprises at least 1 to 30 parts by weight of a matrix polymer; and an elastic article is formed from the composition by curing and thermoforming, wherein (1) the article is an insulator when not subjected to compressive stress and is conductive when subjected to compressive stress, and / or (2) the conductivity level of the article under compressive stress differs from the conductivity level of the article when not subjected to compressive stress, such that the article exhibits at least one of dissipation effect or quantum tunneling effect, and the article has a change in conductivity level under compressive stress when used for immediate measurement and evaluation of the performance of the article.

21. A composition for forming an article comprising: at least one matrix polymer comprising at least one curable polymer having at least one functional group for crosslinking, wherein the curable polymer is selected from the group consisting of curable fluoropolymers, curable perfluoropolyethers and curable perfluoropolymers and blends and copolymers thereof, and a three-dimensional, branched and / or crosslinked carbon nanostructure additive provided in an amount of 1 to 30 parts by weight of the carbon nanostructure additive per 100 parts by weight of the at least one matrix polymer, wherein after crosslinking the matrix polymer and after forming an elastic article from the composition, the article (1) is an insulator when not subjected to compressive stress and is conductive when subjected to compressive stress, and / or (2) the conductivity level of the article under compressive stress differs from the conductivity level of the article when not subjected to compressive stress, such that the article exhibits one or more of a dissipative effect and a quantum tunneling recombination effect, and the article has a change in conductivity level under compressive stress when used for immediate determination and evaluation of the performance of the article.

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