Silicone rubber based nonlinear conductive insulation composite

Abstract

This invention relates to a silicone rubber-based nonlinear conductive insulating composite material composition comprising at least one organopolysiloxane compound A, each molecule of which contains at least two alkenyl groups bonded to silicon atoms; at least one organohydrogen-based polysiloxane compound B; at least one catalyst C; optionally, at least one organosilicon resin D; at least one reinforcing filler E1; at least one conductive filler E2 and / or at least one semiconductor nanoparticle material E3; at least one organic conductive additive F; and optionally, at least one crosslinking inhibitor G. The invention also relates to a silicone rubber-based nonlinear conductive insulating composite material obtained by crosslinking and curing the composition; articles obtained from the composition or the composite material; and the use of the composition or the composite material in the preparation of cable accessories, particularly for high-voltage direct current transmission.

Description

Technical Field

[0001] This invention relates to the field of silicone rubber-based composite materials. More particularly, this invention relates to silicone rubber-based nonlinear conductive insulating composite materials that can be used especially as materials for high-voltage direct current transmission. Background Technology

[0002] With the diversification of energy forms, traditional power equipment, grid structures, and operating technologies are increasingly inadequate to accommodate large-scale, low-quality renewable energy sources. Therefore, new technologies, equipment, and grid structures are necessary to meet the profound changes in the future energy landscape. Overhead transmission corridors required for power capacity expansion are difficult to obtain in urban power grid systems, while the transmission distance of AC underground cable transmission is limited by capacitive current. Currently, DC grids have become a research hotspot among many solutions to these problems, and using underground DC cable transmission can avoid capacitive current issues and achieve long-distance power transmission.

[0003] High-voltage direct current (HVDC) transmission offers advantages such as larger transmission capacity, longer transmission distance, lower transmission losses, and smaller transmission corridor requirements per unit capacity. However, compared to the more mature high-voltage alternating current (HVAC) transmission, the application of HVDC is limited by the development level of cable accessory technology. Within high-voltage cable accessories, the difference in conductivity between the cable and the accessory's insulation materials leads to space charge accumulation, making them highly susceptible to electric field distortion. This can cause the cable accessories to break down due to excessive electric field strength, resulting in failure. In high-voltage transmission systems, most faults occur in cable accessories.

[0004] In DC cable accessories, the conductivity varies significantly with temperature and electric field, leading to a marked change in the electric field distribution. Uneven electric field distribution is a widespread problem in high-voltage power insulation equipment and components, posing significant technical challenges and costs to the design and manufacture of high-voltage equipment, and jeopardizing the long-term safety and reliability of the equipment.

[0005] To address this, one existing solution is to homogenize the electric field by optimizing the structure of the insulation equipment and accessories. However, this approach introduces significant inconvenience for maintenance and replacement during later use. Another solution involves introducing electric field modulation materials with nonlinear conductivity characteristics. These are typically prepared by combining polymers with good insulation properties, such as epoxy resin, EPDM rubber, silicone rubber, and polyolefins, as the matrix material with various inorganic fillers possessing conductive or semi-conductive properties. Numerous studies have reported the use of various types of semiconductor fillers with nonlinear resistivity characteristics. However, in the actual preparation of composite rubber materials, the required addition amount of such fillers when used alone is often very high (e.g., >40% by weight). This not only leads to high raw material viscosity and difficulty in processing but also significantly reduces the mechanical properties and breakdown strength of the finished product.

[0006] US7320762B2 discloses a polymer compound with nonlinear current-voltage characteristics, comprising a polymer matrix and a filler, wherein the filler comprises at least two filler components with different nonlinear current-voltage characteristics. The filler components, for example, are all prepared using zinc oxide as the main raw material, either by doping with other metals in varying amounts or by employing different sintering methods. By adjusting the ratio of the at least two filler components, the nonlinear characteristics of the composite material can be controlled. CN111875965A describes a method for preparing an electric field adaptive composite material based on surface functionalization treatment, including calcining to prepare zinc oxide varistor microspheres, and then using the surface-modified zinc oxide varistor microspheres as a filler in the preparation of the composite material. The filler obtained in this way can increase the interaction with the matrix polymer, thereby improving the electrical, mechanical, and thermal properties of the composite material. The solutions disclosed in the above patent documents all involve secondary processing of commercially available fillers to change their component content, morphology, or size. However, the nonlinear characteristics of the re-sintered filler are unpredictable or cannot be accurately customized, thus requiring extensive trial and error to obtain fillers with the desired performance.

[0007] In existing technologies, attempts have been made to add small amounts of highly conductive fillers, such as conductive carbon black, carbon nanotubes, carbon fibers, graphene, and metal powders, to composite materials, thereby effectively reducing the amount of semiconductor fillers used. For example, CN105255022A and CN105295382B use nano-silicon carbide and nano-graphite as fillers, which can control the conductivity of the composite material within a reasonable range. CN109867964A uses both carbon black and carbon nanotubes as conductive fillers and performs surface treatment to improve the dispersion effect, thereby solving the problem of unstable resistivity of the composite material. CN103214851A and CN105331110A disclose the use of various nonlinear semiconductor fillers and various conductive fillers in combination to solve technical problems such as low breakdown voltage and low mechanical strength of composite materials. US10755833B2 discloses the use of at least one dielectric active compound in an organosilicon composition for preparing insulators for high-voltage DC applications, which can be selected from conductive fillers, semi-conductive fillers, ionic liquids, and ionic polymers. The volume resistivity of the prepared composite material can be controlled within a certain range and exhibits low temperature dependence, making it suitable for use as insulation material for cable joints in high-voltage direct current transmission. The solutions disclosed in the aforementioned patent documents all utilize conductive fillers, but their dosage needs to be close to the percolation threshold of the conductive filler to effectively regulate the nonlinear resistivity of the composite material. This implies that the allowable error range for the material formulation is extremely small, placing extremely stringent requirements on the processing technology, and increasing the likelihood of product performance deviating from requirements. Currently, there is no effective solution.

[0008] The present invention aims to solve the problems of the prior art. Summary of the Invention

[0009] The purpose of this invention is to provide a silicone rubber-based nonlinear conductive insulating composite material, which is particularly suitable for use as a high-voltage direct current (HVDC) transmission material. This silicone rubber-based nonlinear conductive insulating composite material is suitable for HVDC transmission cable accessories, such as cable joint accessories and cable termination accessories, especially stress cones. The silicone rubber-based nonlinear conductive insulating composite material according to the invention possesses various properties particularly suitable for HVDC transmission cable accessories, especially in terms of electrical and mechanical properties. In particular, the conductivity of this silicone rubber-based nonlinear conductive insulating composite material can achieve optimal matching with the operating environment, and through its own conductivity characteristics changing with temperature and electric field, it achieves the effect of automatically homogenizing the electric field differences between different structural components.

[0010] Therefore, the present invention relates to a silicone rubber-based nonlinear conductive insulating composite material composition, comprising:

[0011] - At least one organopolysiloxane compound A, each molecule of which contains at least two alkenyl groups bonded to silicon atoms, preferably C2-C6 alkenyl groups.

[0012] - At least one organohydrogen-based polysiloxane compound B, which preferably contains at least two hydrogen atoms per molecule bonded to the same or different silicon atoms.

[0013] - At least one catalyst C, comprising at least one platinum group metal or compound.

[0014] -Optionally, at least one silicone resin D,

[0015] - At least one reinforcing filler E1, preferably at least one silica.

[0016] - At least one conductive filler E2 and / or at least one semiconductor nanoparticle material E3, preferably at least one conductive filler E2 and at least one semiconductor nanoparticle material E3.

[0017] -At least one organic conductive additive F,

[0018] -Optionally, at least one crosslinking inhibitor G.

[0019] The inventors have unexpectedly discovered that, through the combination of various components used in the silicone rubber-based nonlinear conductive insulating composite material composition of the present invention, particularly the use of the organic conductive additives according to the present invention in the composition of the present invention and / or the combination of the organic conductive additives according to the present invention with conductive fillers and / or semiconductor nanoparticle materials, the obtained silicone rubber-based nonlinear conductive insulating composite material has a variety of advantages, especially in terms of various properties suitable for cable accessories such as stress cones for high voltage direct current transmission, particularly in terms of electrical and mechanical properties.

[0020] In particular, the organic conductive additives used in the silicone rubber-based nonlinear conductive insulating composite material of the present invention not only possess the various properties of organic polymer materials, such as flexibility, deformability, low density, and high compatibility with the matrix, but also, under the action of an electric field, their charge carriers transition in the conductive channels formed within or between the chains of the contained conjugated structures or ionic groups. The semiconductor / conductor electrical properties generated by this transport characteristic can also play a synergistic role in the material preparation process, enhancing the interaction between the silicone rubber matrix and the filler. Moreover, the use of organic conductive additives can not only effectively reduce the amount of conductive fillers and / or semiconductor nanoparticle materials used, thereby significantly increasing the breakdown voltage of the insulating material and thus improving the long-term performance stability of the material; more importantly, it can solve the pain point problem of extremely small allowable error range of formulation and large performance fluctuation faced by such nonlinear conductive insulating materials in industrial applications, resulting in a significant improvement in product production stability and good performance reproducibility. Within the scope of this invention, the formulation (such as specific components and content) of the nonlinear conductive insulating material can be flexibly adjusted within a wide range while still possessing the various properties required for the target application (e.g., cable accessories for high-voltage direct current transmission), particularly electrical and mechanical properties. This significantly reduces the requirements for processing technology and is more conducive to industrial production.

[0021] Furthermore, taking cross-linked polyethylene (XLPE), the mainstream extruded cable insulation material currently used in high-voltage direct current (HVDC) transmission, as an example, its DC conductivity is comprehensively affected by cross-linking byproducts, semi-crystalline microstructure, and polymer processing. The insulation performance of XLPE fluctuates between different batches, with not only orders of magnitude changes in conductivity but also varying trends in conductivity with electric field strength or temperature. If the conductivity of silicone rubber used as cable accessory insulation material is incompatible with that of XLPE, it will lead to the accumulation of interfacial space charge, preventing the electric field from homogenizing. Therefore, for different batches of XLPE, it has been reported that nonlinear silicone rubber materials require readjustment of the semiconductor / conductive filler content, and even adjustments to filler particle size, dielectric properties, and other parameters, undoubtedly resulting in a very large and tedious workload.

[0022] In particular, the conductivity of silicone rubber typically exhibits a weak temperature dependence, meaning its volume resistivity changes little with temperature. XLPE, on the other hand, shows the opposite; its volume resistivity can decrease by up to three orders of magnitude with increasing temperature. Therefore, in different temperature ranges, an electric field reversal can occur between silicone rubber and XLPE, altering the polarity of the interfacial charge. This not only makes the electric field distribution more complex and severely distorted but also increases the likelihood of cable accessory failure.

[0023] The silicone rubber-based nonlinear conductive insulating composite material according to the present invention solves the aforementioned bottleneck problems. Through the combination of various components used in the silicone rubber-based nonlinear conductive insulating composite material composition of the present invention, particularly the use of the organic conductive additive according to the present invention and / or the combination of the organic conductive additive according to the present invention with conductive fillers and / or semiconductor nanoparticle materials, the conductivity of the nonlinear conductive insulating composite material can be effectively adjusted over a wide range to adapt to different batches and properties of XLPE. Furthermore, by changing the type of organic conductive additive according to the present invention, the nonlinear conductive insulating composite material can have different resistivity temperature coefficients, exhibiting either greater or lesser temperature dependence to match practical application requirements.

[0024] The various components that can be used in the compositions of the present invention are further described below.

[0025] Organopolysiloxane compound A

[0026] Each molecule of organopolysiloxane compound A contains at least two alkenyl groups bonded to silicon, preferably C2-C6 alkenyl groups.

[0027] In particular, organopolysiloxane compound A can be formed from the following units:

[0028] -At least two silyloxy units of the following formula: W a Z 1 b SiO (4-a-b) / 2

[0029] in:

[0030] W is an alkenyl group, preferably a C2-C6 alkenyl group, and more preferably a vinyl group.

[0031] Z 1 It is a monovalent hydrocarbon group having 1-12 carbon atoms, preferably selected from alkyl groups having 1-8 carbon atoms such as methyl, ethyl, and propyl, cycloalkyl groups having 3-8 carbon atoms, and aryl groups having 6-12 carbon atoms.

[0032] a = 1 or 2, b = 0, 1 or 2, and a + b = 1, 2 or 3; and

[0033] -Optionally, the unit of the following formula: Z 1 c SiO (4-c) / 2

[0034] Z 1 It has the same meaning as above and c = 0, 1, 2 or 3.

[0035] It should be understood that in the above formula, if multiple groups Z exist... 1 If they are the same as or different from each other, then they can be the same as or different from each other.

[0036] Organopolysiloxane compound A can have a linear, branched, or cyclic structure. Their degree of polymerization can be, for example, 2-5000, such as 100-3000, such as 200-2000.

[0037] According to one embodiment, the organopolysiloxane compound A used in this invention has a dynamic viscosity of 10-50,000,000 mPa·s at 25°C, for example 200-20,000,000 mPa·s, for example 1,000-10,000,000 mPa·s, for example 2,000-150,000 mPa·s.

[0038] Unless otherwise indicated, the viscosity considered in this specification corresponds to the “Newtonian” dynamic viscosity at 25°C, i.e., the dynamic viscosity measured in a manner known per se using a Brookfield viscometer at a sufficiently low shear rate gradient that makes the measured viscosity independent of the velocity gradient.

[0039] According to a preferred embodiment, organopolysiloxane compound A is a linear organopolysiloxane, such as poly(dimethylsiloxane) having a dimethylvinylsilyl end; poly(dimethylsiloxane-co-methylphenylsiloxane) having a dimethylvinylsilyl end; poly(dimethylsiloxane-co-methylvinylsiloxane) having a dimethylvinylsilyl end; poly(dimethylsiloxane-co-methylvinylsiloxane) having a trimethylsilyl end, etc.

[0040] Preferably, organopolysiloxane compound A comprises a terminal dimethylvinylsilyl unit, and more preferably, organopolysiloxane A is a poly(dimethylsiloxane) having a dimethylvinylsilyl terminal.

[0041] According to a preferred embodiment, organopolysiloxane compound A is a compound of general formula (1):

[0042]

[0043] Wherein, n represents an integer from 0 to 100, preferably an integer from 10 to 50; m represents an integer from 70 to 4000, preferably an integer from 150 to 2000; R is a saturated hydrocarbon group, such as selected from methyl, ethyl, propyl, butyl, etc.; R 1 It is an unsaturated hydrocarbon group, such as selected from vinyl, allyl, allyl, etc.; R 2 It is a saturated or unsaturated hydrocarbon group, such as selected from methyl, ethyl, vinyl, propyl, allyl, butyl, and allyl.

[0044] According to a preferred embodiment, the compound of general formula (1) is wherein R 1 Vinyl and R 2 Terminal vinyl silicone oils with saturated hydrocarbon groups, and / or wherein R 1 It is a saturated hydrocarbon group and R 2 Vinyl side-chain vinyl silicone oil, and / or R therein 1 and R 2 Both are vinyl-terminated vinyl silicone oils.

[0045] Preferably, the mass content of vinyl groups in the compound of general formula (1) is 0.02-5% of the total mass of the compound of general formula (1), for example, 0.05-3%. The appropriate mass content of vinyl groups selected according to the invention can particularly improve the overall performance of the final product.

[0046] Organohydrogen-based polysiloxane compound B

[0047] The organohydrogen-based polysiloxane compound B preferably contains at least two hydrogen atoms per molecule that are bonded to the same or different silicon atoms.

[0048] Advantageously, organohydrogen-based polysiloxane compound B can be an organopolysiloxane containing at least two, preferably at least three, silanoxy units of the following formula: H d Z 2 e SiO (4-d-e) / 2

[0049] in:

[0050] -Group Z 2 The same or different indicates a monovalent hydrocarbon group comprising 1-30, preferably 1-12 carbon atoms, which is optionally substituted, for example, by at least one halogen such as fluorine or chlorine; preferably selected from alkyl groups comprising 1-8 carbon atoms, cycloalkyl groups comprising 3-8 carbon atoms, and aryl groups comprising 6-12 carbon atoms, and even more preferably selected from methyl, ethyl, propyl, 3,3,3-trifluoropropyl, xylyl, tolyl, and phenyl.

[0051] -d = 1 or 2, e = 0, 1 or 2 and d + e = 1, 2 or 3;

[0052] And optionally, other units of the following formula: Z 2 f SiO (4-f) / 2

[0053] Z 2 It has the same meaning as above, and f = 0, 1, 2 or 3.

[0054] It should be understood that in the above formula, if multiple groups Z exist... 2 If they are the same as or different from each other, then they can be the same as or different from each other.

[0055] In the above formula, the symbol d is preferably equal to 1.

[0056] According to a preferred embodiment, organohydrogen-based polysiloxane compound B is an organosiloxane containing at least two hydrogen atoms per molecule bonded to the same or different silicon atoms, and preferably at least three hydrogen atoms per molecule directly bonded to the same or different silicon atoms.

[0057] Organohydrogen-based polysiloxane compounds B can have linear, branched, or cyclic structures. Their degree of polymerization can be, for example, 2-5000, such as 100-3000, such as 200-2000.

[0058] According to one embodiment, the organohydrogen-based polysiloxane compound B according to the present invention has a dynamic viscosity of 1-100,000 mPa·s, for example 10-50,000 mPa·s, or for example 100-5,000 mPa·s at 25°C.

[0059] According to a preferred embodiment, organohydrogen-based polysiloxane compound B is a linear organohydrogen-based polysiloxane compound. The linear organohydrogen-based polysiloxane compound B can be an organohydrogen-based polysiloxane containing Si-H units in the chain and / or at the chain ends. Examples of linear organohydrogen-based polysiloxane compound B include: dimethyl polysiloxanes with dimethylsilyl end groups, dimethylhydromethyl polysiloxanes with trimethylsilyl end groups, dimethylhydromethyl polysiloxanes with dimethylsilyl end groups, and hydromethyl polysiloxanes with trimethylsilyl end groups.

[0060] Cyclic organohydrogen-based polysiloxane compound B can be, for example, a cyclic hydrogen-based methyl polysiloxane.

[0061] According to a preferred embodiment, organohydrogen-based polysiloxane compound B is a compound of general formula (2):

[0062]

[0063] Where x is an integer from 0 to 200, preferably an integer from 10 to 100; y is an integer from 0 to 60, preferably an integer from 5 to 20; R 3 Choose from methyl, hydrogen, or silane groups; R 4 It can be selected from methyl, ethyl, propyl or phenyl.

[0064] According to a preferred embodiment, the compound of general formula (2) is wherein R 3 Hydrogen-containing silicone oils with hydrogen groups and y greater than 1, containing Si-H at both ends and in the side chains, and / or compounds of general formula (2) wherein R 3 Hydrogen-terminated silicone oils with a hydrogen group and y = 0, and / or compounds of general formula (2) wherein R 3 Hydrogen-containing silicone oil with a saturated hydrocarbon group and a y value greater than 1 as its side chain.

[0065] Catalyst C

[0066] The catalyst according to the invention comprises at least one platinum group metal or compound. Platinum group metals are those metals known by the name platinum group metals, a term that includes ruthenium, rhodium, palladium, osmium and iridium in addition to platinum, preferably platinum or rhodium.

[0067] According to a preferred embodiment, the catalyst is a platinum-based catalyst, which may be selected from chloroplatinic acid, an alcoholic solution of chloroplatinic acid, a platinum complex catalyst, a coated platinum catalyst, or a mixture thereof.

[0068] According to one embodiment, the catalyst is a platinum complex catalyst, wherein the ligand is selected from organophosphorus ligands, hindered amine ligands, borane ligands, carbene ligands, organosiloxane ligands such as modified vinylsiloxane ligands, olefin ligands, ethyl acetoacetate ligands, acetylacetone ligands, or combinations thereof.

[0069] According to a preferred embodiment, the catalyst may be selected from platinum and olefin complexes, bis(ethyl acetoacetate)platinum, bis(acetylacetone)platinum, platinum and organopolysiloxane complexes such as platinum and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane complexes (referred to as casterplatin catalysts), more preferably casterplatin catalysts.

[0070] According to a preferred embodiment, the encapsulated platinum catalyst may be selected from microencapsulated platinum catalysts, such as matrix or core-shell type platinum catalysts.

[0071] Preferably, the catalyst according to the present invention can be selected from coated platinum catalysts, platinum complex catalysts, or mixtures thereof; the use of these types of catalysts can have the effect of resisting catalyst poisoning, for example, avoiding the problem of catalyst poisoning caused by impurity elements (such as N, P, etc.) in the materials used (such as organic conductive additives) and thus affecting the subsequent crosslinking and curing.

[0072] The catalyst is used in a catalytically effective amount. Those skilled in the art can select an appropriate amount of catalyst to use.

[0073] Organosilicon resin D

[0074] Organosilicon resins are well-known and commercially available. Organosilicon resins have at least two distinct units in their structure, said units being selected from units having the following formula: R 0 3SiO 1 / 2 (M unit), R 0 2SiO 2 / 2 (D unit), R 0 SiO 3 / 2 (T unit) and SiO 4 / 2 (Q unit), at least one of these units is a T or Q unit, wherein the group R 0 They may be the same or different and can be selected from linear or branched C1-C6 alkyl, C2-C6 alkenyl, hydroxyl, hydrogen, phenyl, 3,3,3-trifluoropropyl. The alkyl group may be, for example, methyl, ethyl, isopropyl, tert-butyl, and n-hexyl; the alkenyl group may be vinyl, allyl, or allyl.

[0075] Examples of silicone resins include MQ resin, MDQ resin, TD resin, MTQ resin, MDTQ resin and MDT resin, wherein optionally, substituent functional groups (e.g. vinyl, hydrogen) may be carried by M, D and / or T units.

[0076] According to a preferred embodiment, the organosilicon resin according to the present invention is a compound of general formula (3):

[0077]

[0078] Where a is an integer from 1 to 300, for example, an integer from 10 to 200; R 5 It can be selected from methyl, ethyl, vinyl, or hydrogen groups.

[0079] According to a preferred embodiment, the compound of general formula (3) is a subset of R. 5 It is a vinyl-based silicone resin.

[0080] According to a preferred embodiment, the compound of general formula (3) is a subset of R. 5 It is a hydrogen-based, hydrogen-containing organosilicon resin.

[0081] According to one embodiment variation, when the silicone resin D is a hydrogen-containing silicone resin, it can partially or completely replace the organohydrogen-based polysiloxane compound B. In this embodiment variation, as an alternative, the silicone rubber-based nonlinear conductive insulating composite material composition according to the invention may contain the hydrogen-containing silicone resin D, which can partially or completely function as an organohydrogen-based polysiloxane. In this case, the amount of organohydrogen-based polysiloxane compound B can be reduced, or even omitted entirely. Therefore, according to a particular embodiment, the composition of the invention contains only the hydrogen-containing silicone resin D as the organohydrogen-based polysiloxane.

[0082] At least one reinforcing filler E1

[0083] The compositions according to the invention may contain at least one reinforcing filler, for example, to obtain good mechanical strength.

[0084] According to a preferred embodiment, the reinforcing filler is silica, preferably selected from precipitated silica and fumed silica and mixtures thereof.

[0085] The BET specific surface area of ​​the silica can be at least 150 m². 2 / g, and preferably 200-400m 2 / g, for example, 250-300m 2 / g.

[0086] In a preferred embodiment, the silica-reinforcing filler has a BET specific surface area of ​​at least 150 m². 2 / g and preferably 250-400m 2 / g of fumed silica.

[0087] Unless otherwise stated, the specific surface area referred to in this application means the BET specific surface area measured using nitrogen and the BET method in accordance with standard ISO 9277:2010.

[0088] The silica (preferably fumed silica) can be used as is in its untreated form, but it is preferred to undergo a hydrophobic surface treatment.

[0089] If hydrophobic surface-treated silica (preferably fumed silica) is used, pre-treated silica can be used, or a surface-treatment agent can be added when silica is mixed with other components (e.g., during mixing with organopolysiloxane compound A, or during the preparation of the base adhesive) to treat silica in situ.

[0090] The surface treatment agent can be selected from any commonly used reagents, such as alkylalkoxysilanes, alkylchlorosilanes, silazanes, silane coupling agents, titanate-based treatment agents, and fatty acid esters. A single treatment agent can be used, or a combination of two or more treatment agents can be used, wherein the two or more treatment agents can be used simultaneously or at different times.

[0091] According to a preferred embodiment, the surface treatment agent is selected from hexamethyldisilazane, tetramethyldivinylsilazane, heptamethyldisilazane, octamethylcyclotetrasilazane, vinyl monoterminated silazane, or mixtures thereof, more preferably hexamethyldisilazane and / or tetramethyldivinylsilazane.

[0092] Conductive filler E2

[0093] The conductive filler used in this invention can be any material known in the art that is suitable for conducting electricity.

[0094] According to a preferred embodiment, the conductive filler is selected from carbon nanotubes, graphene, superconducting carbon black, nanographite sheets, carbon fibers, Mxenes, or mixtures thereof, with carbon nanotubes being preferred.

[0095] Carbon nanotubes are tubular carbon nanomaterials, generally classified into single-walled carbon nanotubes and multi-walled carbon nanotubes. Their diameter is on the nanometer scale and they have a high aspect ratio.

[0096] Carbon nanotubes themselves have excellent electrical conductivity, and they can be combined with polymer materials to impart good electrical properties to the polymer materials.

[0097] According to one embodiment, the carbon nanotubes according to the present invention can have a thickness of 10-1000 μm. 2 / g, for example 50-600m 2 / g, for example 100-500m 2 / g BET specific surface area.

[0098] The carbon nanotubes used in this invention may be selected from single-walled carbon nanotubes, multi-walled carbon nanotubes, or mixtures thereof.

[0099] According to a preferred embodiment, the average diameter of the single-walled carbon nanotube is 0.2-5 nm, for example 0.4-2 nm, for example 1-1.8 nm, for example 1.2-1.5 nm, and / or the length of the single-walled carbon nanotube is 5 nm-200 μm, for example 10 nm-100 μm, for example 50 nm-50 μm, for example 100 nm-20 μm.

[0100] According to a preferred embodiment, the average diameter of the multi-walled carbon nanotube is 2-100 nm, for example 10-60 nm, for example 20-40 nm, and / or the length of the multi-walled carbon nanotube is 5 nm-200 μm, for example 10 nm-100 μm, for example 50 nm-50 μm, for example 100 nm-10 μm, for example 0.5 μm-5 μm.

[0101] For example, according to the present invention, a diameter <10nm, a length of 1-50μm, and a BET specific surface area of ​​100-500m² can be selected. 2 / g of single-walled or multi-walled carbon nanotubes.

[0102] Semiconductor nanoparticle material E3

[0103] Semiconductor nanoparticle materials refer to semiconductor materials in the form of nanoparticles, which have the meaning known in the art. For example, the particle refers to a particle whose size is at least nanometer-scale (e.g., less than 1000 nm, e.g., less than 800 nm).

[0104] Preferably, the semiconductor nanoparticle material may have an average particle size of 1-800 nm, for example 5-600 nm, for example 10-500 nm, for example 50-300 nm, for example 100-200 nm.

[0105] The average particle size can be determined according to methods known in the art. For example, the average particle size can be the equivalent volume diameter measured by a common laser method. For example, the average particle size can be measured according to standard GB / T 19077-2016.

[0106] Preferably, the semiconductor nanoparticle material can have a size of 1-200 μm. 2 / g, for example 5-150m 2 / g, for example 10-120m 2 / g, for example 20-100m 2 / g, for example 50-80m 2 / g BET specific surface area.

[0107] The semiconductor nanoparticle material can be selected from aluminum oxide, antimony tin oxide, cerium oxide, copper oxide, indium oxide, indium tin oxide, iron oxide, tin oxide, titanium dioxide, zinc oxide, chromium oxide, magnesium oxide, manganese oxide, molybdenum oxide, silicon carbide, copper calcium titanate, lead titanate, strontium titanate, barium titanate, barium strontium titanate, aluminum nitride, lead zirconate titanate, or mixtures thereof.

[0108] According to one embodiment, the semiconductor nanoparticle material is selected from titanium dioxide, silicon carbide, barium titanate, zinc oxide, or mixtures thereof.

[0109] According to a preferred embodiment, the titanium dioxide may have a surface area of ​​30-150 μm. 2 / g, for example 50-120m 2 The BET specific surface area is 2-800 nm, for example 5-100 nm, for example 10-50 nm. According to a preferred embodiment, the silicon carbide may have a BET specific surface area of ​​10-100 nm. 2 / g, for example 20-80m 2 The BET specific surface area per g, and / or the average particle size of the silicon carbide is 10-100 nm, for example 20-50 nm.

[0110] According to a preferred embodiment, the barium titanate may have a content of 1-100 μm. 2 / g, for example 5-20m 2 The BET specific surface area per g, and / or the average particle size of the barium titanate is 20-800 nm, for example 50-500 nm, for example 100-300 nm.

[0111] According to a preferred embodiment, the zinc oxide may have a concentration of 1-100 μm. 2 / g, for example 4-50m 2 The BET specific surface area per g, and / or the average particle size of the zinc oxide is 1-200 nm, for example 20-150 nm, for example 40-100 nm.

[0112] Organic conductive additive F

[0113] According to one embodiment, the organic conductive agent F can be selected from silicon-containing π-conjugated polymers, doped or undoped π-conjugated conductive polymers, organosilicon polymers with σ-π conjugation in the main chain, organic ionic liquids, and mixtures thereof.

[0114] The organic conductive additives used according to the present invention will be further described below.

[0115] (1) Silicon-containing π-conjugated polymers

[0116] The silicon-containing π-conjugated polymer can be selected from silane compounds containing π-conjugated structural groups, linear polysiloxanes or branched polysiloxanes, stacked phthalocyanine polysiloxanes, polysiloxane-modified liquid phthalocyanines, and mixtures thereof.

[0117] According to one embodiment, the silane compound, linear polysiloxane, or branched polysiloxane containing π-conjugated structural groups may contain, for example, π-conjugated structural groups selected from the following:

[0118]

[0119] The conjugated structural group can be directly attached to a Si atom, or attached to the α and / or γ carbon atoms of Si.

[0120] According to a preferred embodiment, the silicon-containing π-conjugated polymer is a linear polysiloxane containing side-chain π-conjugated structural groups, which may be selected, for example, from linear polysiloxanes containing conjugated structural side-chain groups of the following formula or mixtures thereof:

[0121]

[0122] Where n = 1-200, for example 5-100, for example 10-50; m = 0-500, for example 1-400, for example 10-300, for example 50-200.

[0123] According to one embodiment, the polysiloxane chain of the linear polysiloxane containing side-chain π-conjugated structural groups may contain alkenyl groups and / or Si-H, and / or the end-capping groups may be methyl groups and / or Si-H, etc.

[0124] According to a preferred embodiment, the silicon-containing π-conjugated polymer is a branched polysiloxane containing π-conjugated structural groups, which can be selected from a silicone resin having one or more of the above-mentioned conjugated groups, for example having the following structure:

[0125]

[0126] R1 can represent a saturated hydrocarbon group, such as methyl, ethyl, propyl, butyl, etc.

[0127] This stacked phthalocyanine polysiloxane is formed by passing a polysiloxane backbone (such as poly(methylphenylsiloxane) or poly(methylpropylsiloxane)) through the phthalocyanine ring to stack phthalocyanines together, and charge carriers can be injected from the phthalocyanines into the organosilicon polymer.

[0128] The phthalocyanine structure is shown below:

[0129]

[0130] This polysiloxane-modified liquid phthalocyanine is formed by introducing siloxane oligomers (such as dimethylsiloxane oligomers) into phthalocyanine molecules through chemical bonds.

[0131] According to one embodiment, the oligomer has, for example, the following structure:

[0132] Where n = 1-100, for example 5-20;

[0133] It can undergo a cyclotetramerization reaction under the action of a catalyst to generate liquid phthalocyanine.

[0134] As an advantage, liquid phthalocyanine is easy to incorporate into the composite material compositions of the present invention.

[0135] According to a particularly preferred embodiment, the silicon-containing π-conjugated polymer may be selected from silane compounds containing π-conjugated structural groups, linear polysiloxanes, or branched polysiloxanes, with linear polysiloxanes containing side-chain π-conjugated structural groups being particularly preferred.

[0136] (2) Doped or undoped π-conjugated conductive polymers

[0137] This doped or undoped π-conjugated conductive polymer differs from the silicon-containing π-conjugated polymer described above. For example, this doped or undoped π-conjugated conductive polymer is a silicon-free π-conjugated conductive polymer.

[0138] The doped or undoped π-conjugated conductive polymer can be selected from, for example, doped or undoped polyaniline (PANI), polypyrrole (PPy), polythiophene (PT) and related derivatives with high thermal stability, such as poly(3,4-vinyldioxythiophene) (PEDOT), polyhexylthiophene (PHT), etc.

[0139] According to a preferred embodiment, the π-conjugated conductive polymer may be selected from polymers having the following structure: Where n = 10-200, for example 20-100, for example 30-50.

[0140] The π-conjugated conductive polymer can take on different forms, such as nanowires, nanoparticles, fibers, powders, etc., depending on its properties.

[0141] For example, polyaniline can typically be prepared in the form of nanoparticles or nanofibers, which can be directly added as fillers to the compositions of the present invention for dispersion, mixing, and processing. Other π-conjugated conductive polymers, such as PHT, can be dissolved in chloroform first, and then mixed evenly with a certain proportion of silicone oil. After the mixture is slowly heated to remove the chloroform, a PHT mixture dispersed in silicone oil can be obtained. This mixture can be added as a mother liquor to the compositions of the present invention.

[0142] The π-conjugated conductive polymer can be doped or undoped. Doping significantly improves the conductivity of the π-conjugated conductive polymer, but when exposed to air, the counterions in the dopant gradually decrease due to oxidation, leading to a gradual decline in conductivity. Therefore, this invention preferably uses a macromolecular polyelectrolyte to dope the π-conjugated conductive polymer to improve its conductivity and simultaneously improve its relatively weak processability. The dopant is preferably a polysiloxane or polyphosphazene with a flexible backbone and ionic side groups.

[0143] Preferably, the doped electrolyte is an organic electrolyte, such as poly(sodium styrene sulfonate) (PSS) or sulfonated polysiloxane (PSiPS) of the following formula:

[0144]

[0145] Where n = 1-100, for example n = 5-50, for example n = 10-30.

[0146] According to a particularly preferred embodiment, the doped or undoped π-conjugated conductive polymer is selected from doped or undoped poly(3,4-vinyldioxythiophene) (PEDOT) and polyhexylthiophene (PHT), and is particularly preferably doped with sulfonated polysiloxane or other ionic polysiloxanes such as PEDOT or PHT.

[0147] (3) Organosilicon polymers with σ-π conjugation in the main chain

[0148] The main chain containing σ-π conjugated organosilicon polymers can be selected from polymers with alternating oligomeric silyl groups and π-electron groups, silicon-containing π-conjugated heterocyclic polymers, polymers based on thiorrole (silylcyclopentadiene), etc.

[0149] According to one embodiment, the organosilicon polymer containing σ-π conjugation in its main chain may have the following formula:

[0150]

[0151] Where Ar can be

[0152] R 1 Indicates alkyl groups such as methyl and ethyl, and aryl groups such as phenyl;

[0153] R 2 Indicates alkyl groups such as methyl, aryl groups such as phenyl, etc.;

[0154] a can be 1-5, for example, 2-4;

[0155] b is 1-5, for example 2-4;

[0156] m is 1-100, for example, 10-50;

[0157] Where n is 1-50, for example 5-30, and X represents H, Br, or Cl atoms; or

[0158] Thiol polymers: Where x is And so on, n = 1-50, for example 5-30.

[0159] According to a particularly preferred embodiment, the organosilicon polymer containing σ-π conjugation in the main chain is a thiophene polymer.

[0160] (4) Organic ionic liquids

[0161] This organic ionic liquid comprises a combination of organic cations and inorganic or organic anions, wherein the organic cations can be of various types. Common organic cations can be selected from imidazole cations, pyridine cations, quaternary ammonium salt cations, and so on. Salt cations, pyrrole cations, piperidine cations, etc. Common organic anions can be selected from tetrafluoroborate ions, hexafluorophosphate ions, etc.

[0162] The organic ionic liquid can also be a linear or hyperbranched organosilicon ionic liquid, etc.

[0163] According to a particularly preferred embodiment, the organic ionic liquid is an ionic liquid-based polysiloxane, i.e., an ionic liquid containing polysiloxane segments.

[0164] Particularly preferably, in order to improve the compatibility of the organic conductive additive with the organosilicon composition according to the present invention, the organic conductive additive contains organosilicon groups or siloxane chemical bonds in its structure or any component.

[0165] Crosslinking inhibitor G

[0166] The crosslinking inhibitor used according to the present invention can be an inhibitor conventionally used in the organosilicon composition system of the present invention. According to a preferred embodiment, the crosslinking inhibitor can be selected from alkynyl alcohols, preferably selected from 3-methyl-1-butyn-3-ol, 2-methyl-3-butyn-2-ol, 3-butyn-1-ol, 3-butyn-2-ol, propyne alcohol, 2-phenyl-2-propyn-1-ol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-dodecyn-3-ol, 1-ethynylcyclopentanol, 1-phenyl-2-propynol, 3-methyl-1-penten-4-yn-3-ol, 1-ethynyl-1-cyclohexanol (ECH) or mixtures thereof, and particularly preferably selected from 1-ethynyl-1-cyclohexanol, 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-dodecyn-3-ol or mixtures thereof.

[0167] Regarding the dosage of each component in the silicone rubber-based nonlinear conductive insulating composite material composition of the present invention, within the scope of the present invention, those skilled in the art can select or adjust the appropriate dosage of each component according to the actual situation.

[0168] According to a preferred embodiment, the silicone rubber-based nonlinear conductive insulating composite material composition comprises:

[0169] -10-90% by weight, preferably 20-80% by weight, more preferably 30-70% by weight of at least one organopolysiloxane compound A, and / or

[0170] -0.1-10.0 wt%, preferably 0.2-5.0 wt%, more preferably 0.5-3.0 wt%, of at least one organohydrogen-based polysiloxane compound B, and / or

[0171] -0.001-1.000 wt%, preferably 0.002-0.500 wt%, more preferably 0.005-0.050 wt%, of at least one catalyst C, and / or

[0172] -0.1-15.0 wt%, preferably 0.5-10.0 wt%, more preferably 1.0-5.0 wt% of at least one organosilicon resin D, and / or

[0173] -5-50% by weight, preferably 10-40% by weight, more preferably 15-30% by weight of at least one reinforcing filler E1, and / or

[0174] -0.001-1.000 wt%, preferably 0.01-0.50 wt%, more preferably 0.03-0.30 wt%, of at least one conductive filler E2, and / or

[0175] -1-50% by weight, preferably 2-40% by weight, more preferably 5-30% by weight, of at least one semiconductor nanoparticle material E3, and / or

[0176] -0.1-20.0% by weight, preferably 0.5-15.0% by weight, more preferably 1.0-10.0% by weight of at least one organic conductive agent F, and / or

[0177] -0.002-1.000 wt%, preferably 0.005-0.500 wt%, more preferably 0.01-0.20 wt%, of at least one crosslinking inhibitor G.

[0178] Based on the total weight of the composition, and the sum of the contents of each component in the composition is 100% by weight.

[0179] Preparation of the silicone rubber-based nonlinear conductive insulating composite material composition according to the present invention

[0180] The silicone rubber-based nonlinear conductive insulating composite material composition according to the present invention can be prepared by mixing various components.

[0181] According to one embodiment, the silicone rubber-based nonlinear conductive insulating composite material composition according to the invention can be prepared from a two-component (or multi-component) system, wherein the system is provided in the form of two (or more) separate parts, wherein the respective parts are intended to be mixed to form the composition.

[0182] For example, the organosilicon composition can be prepared from a two-component system, one part of which may contain organopolysiloxane compound A, reinforcing filler E1 and catalyst C and exclude organohydrogen-based polysiloxane compound B, while the other part may contain organopolysiloxane compound A, organohydrogen-based polysiloxane compound B, organosilicon resin D, reinforcing filler E1, conductive filler E2, semiconductor nanoparticle material E3, organic conductive agent F and crosslinking inhibitor G and exclude catalyst C.

[0183] Those skilled in the art can choose an appropriate method to prepare the silicone rubber-based nonlinear conductive insulating composite material composition according to actual needs.

[0184] Preferably, the silicone rubber-based nonlinear conductive insulating composite material composition according to the present invention is in liquid form.

[0185] According to a specific embodiment, the silicone rubber-based nonlinear conductive insulating composite material composition comprises components A and B, as well as semiconductor nanoparticle material E3, conductive filler E2, and organic conductive additive F, wherein:

[0186] Component A comprises: base adhesive, at least one compound of general formula (1), and catalyst;

[0187] Component B comprises: base adhesive, at least one compound of general formula (1), at least one compound selected from compounds of general formula (2) and general formula (3), and crosslinking inhibitor;

[0188] The base adhesive may contain at least one compound of general formula (1), such as vinyl silicone oil, reinforcing fillers such as in-situ or pre-treated silica with silazane, and deionized water.

[0189] The present invention also relates to a method for preparing the silicone rubber-based nonlinear conductive insulating composite material composition, comprising the following steps:

[0190] (1) Mix at least one organopolysiloxane compound A, such as vinyl silicone oil, at least one reinforcing filler E1, such as silica surface-treated with silazane, and water to prepare a base adhesive;

[0191] (2) Mix the base adhesive, at least one organopolysiloxane compound A such as a compound of general formula (1), and catalyst C to prepare component A;

[0192] (3) Mix the base adhesive, at least one organopolysiloxane compound A such as a compound of general formula (1), at least one compound selected from organohydrogen-based polysiloxane compound B such as a compound of general formula (2), and organosilicon resin D such as a compound of general formula (3), and optionally an inhibitor to prepare component B.

[0193] (4) Disperse conductive filler E2, semiconductor nanoparticle material E3 and organic conductive additive F into component B to obtain component B1 containing dispersed conductive filler E2, semiconductor nanoparticle material E3 and organic conductive additive F.

[0194] (5) Mix component A and component B1 to obtain a silicone rubber-based nonlinear conductive insulating composite material composition.

[0195] The following provides a more detailed explanation of each step.

[0196] Step (1): Preparation of base adhesive

[0197] According to one embodiment, the base adhesive is obtained by uniformly mixing vinyl silicone oil, silica, a surface treatment agent such as silazane, and deionized water.

[0198] According to one embodiment, the base adhesive comprises a thoroughly mixed vinyl silicone oil, silica, a surface treatment agent such as silazane, and deionized water. Preferably, the base adhesive comprises 30-70 parts by weight of vinyl silicone oil, 15-40 parts by weight of silica, 5-15 parts by weight of silazane, and 1-10 parts by weight of deionized water; more preferably, the base adhesive comprises 50-65 parts by weight of vinyl silicone oil, 25-30 parts by weight of silica, 7-9 parts by weight of silazane, and 3-6 parts by weight of deionized water.

[0199] The vinyl silicone oil used in the base adhesive is preferably an end-vinyl silicone oil, a polyvinyl silicone oil, or a mixture thereof.

[0200] Preferably, the viscosity of the end-group vinyl silicone oil does not exceed 150,000 mPa·s, and more preferably 50,000-60,000 mPa·s. According to one embodiment, the end-group vinyl silicone oil is preferably an alkyl vinyl silicone oil, and more preferably a methyl vinyl silicone oil. Advantageously, by optimizing the selection of the specific type, combination, and viscosity of the vinyl silicone oil, the mechanical properties of the nonlinear conductive insulating composite material can be further improved.

[0201] The silica used in the base adhesive is preferably fumed silica treated with a pretreatment agent, and its BET specific surface area is generally not less than 150 m². 2 / g, preferably 250-400m 2 / g.

[0202] The treatment agent may be selected from hexamethyldisilazane, tetramethyldivinylsilazane, heptamethyldisilazane, octamethylcyclotetrasilazane, vinyl monoterminated silazane, or mixtures thereof, more preferably hexamethyldisilazane and / or tetramethyldivinylsilazane.

[0203] According to a specific implementation scheme, vinyl silicone oil, silica, silazane and deionized water are thoroughly mixed at a temperature of 60-90°C under an inert atmosphere. Then, the temperature is raised to 130-180°C and vacuuming is started. During vacuuming, the temperature is maintained at 130-180°C. After vacuuming is completed, the temperature is lowered to 120-140°C, and then diluted vinyl silicone oil is added and stirred evenly to obtain the base adhesive.

[0204] According to a more specific embodiment, 35-45 parts by weight of vinyl-terminated silicone oil with a viscosity of 50,000-60,000 mPa·s and 22-28 parts by weight of BET specific surface area of ​​250-400 m² are added in a kneader or planetary mixer. 2 / g of fumed silica, 5-6 parts by weight of hexamethyldisilazane, 0.04-0.06 parts by weight of tetramethyldivinylsilazane, and 2-3 parts by weight of deionized water are thoroughly mixed at 80°C under an inert atmosphere for 1.5 hours. Then, the mixture is heated to 140°C and vacuumed for 3 hours, maintaining the temperature at 160°C during vacuuming. The mixture is then cooled to 125°C, and 18-22 parts of methyl vinyl silicone oil with a viscosity of 60000 mPa·s are added. The mixture is stirred until homogeneous to obtain liquid silicone rubber base.

[0205] Step (2): Preparation of component A

[0206] According to one embodiment, component A is obtained by uniformly mixing a base adhesive, at least one compound of general formula (1) and a catalyst and then degassing under vacuum.

[0207] According to a specific embodiment, 100 parts by weight of the base adhesive, 18 parts by weight of terminal vinyl silicone oil with a viscosity of 20000 mPa·s, 18 parts by weight of terminal vinyl silicone oil with a viscosity of 60000 mPa·s, 5 parts by weight of side-chain vinyl silicone oil with a viscosity of 1000 mPa·s, and 0.02 parts by weight of caster catalyst are weighed and dispersed in a planetary mixer for 35 minutes. After mixing evenly, the mixture is degassed under vacuum to obtain component A.

[0208] Step (3): Preparation of component B

[0209] According to one embodiment, component B is obtained by uniformly mixing a base adhesive, at least one compound of general formula (1), at least one compound selected from general formula (2) and general formula (3) and an inhibitor, and then degassing under vacuum.

[0210] According to a specific implementation scheme, 100 parts by weight of the base adhesive, 10-20 parts by weight of terminal vinyl silicone oil with a viscosity of 20000 mPa·s, 3 parts by weight of side-chain vinyl silicone oil with a viscosity of 1000 mPa·s, 1.2-2.0 parts by weight of hydrogen-containing silicone oil with a hydrogen content of 0.7% by mass and containing Si-H at both ends and on the side chains, 1.5 parts by weight of terminal hydrogen-containing silicone oil with a hydrogen content of 0.2% by mass, 5-10 parts by weight of MQ silicone resin with a vinyl content of 1.5-4.0% by mass and a Mw of 4000-20000 (for ease of addition, it can be pre-dissolved in high-viscosity vinyl silicone oil at a concentration of 50%, i.e., the total amount is 10-20 parts by weight), and 0.05-0.15 parts by weight of 1-ethynyl-1-cyclohexanol are stirred and dispersed in a planetary mixer for 35 minutes. After mixing evenly, the mixture is degassed under vacuum to obtain component B.

[0211] According to a preferred embodiment, the compound of general formula (1) is wherein R 1 Vinyl and R 2 Terminal vinyl silicone oils with saturated hydrocarbon groups, and / or wherein R 1 It is a saturated hydrocarbon group and R 2 Vinyl side-chain vinyl silicone oil, and / or R therein 1 and R 2 Both are vinyl-terminated vinyl silicone oils.

[0212] Preferably, the mass content of vinyl groups in the compound of general formula (1) is 0.02-5% of the total mass of the compound of general formula (1). The appropriate mass content of vinyl groups selected according to the invention can particularly improve the overall performance of the final product.

[0213] As one embodiment variation, component B may contain compounds of general formula (2) but not compounds of general formula (3), or component B may contain compounds of general formula (3) but not compounds of general formula (2). In this embodiment variation, when component B contains only compounds of general formula (2), y = 0 and R 3 The two conditions of methylation do not exist simultaneously; when component B contains only compounds of general formula (3), R 5 It is hydrogen-based. When component B contains one or more of the compounds of general formula (2) and general formula (3), at least one of the compounds of general formula (2) and general formula (3) has a Si-H bond.

[0214] According to a preferred embodiment, the compound of general formula (2) is wherein R 3 Hydrogen-containing silicone oils with hydrogen groups and y greater than 1, containing Si-H at both ends and in the side chains, and / or compounds of general formula (2) wherein R 3Hydrogen-terminated silicone oils with a hydrogen group and y = 0, and / or compounds of general formula (2) wherein R 3 Hydrogen-containing silicone oils with side chains that are saturated hydrocarbon groups and y greater than 1, and / or compounds of general formula (3) wherein R 5 It is a hydrogen-based, hydrogen-containing silicone resin.

[0215] Preferably, in order to improve the overall performance of the final product, the mass content of Si-H groups in the at least one compound selected from general formula (2) and general formula (3) is 3%-50% of the total mass of the at least one compound selected from general formula (2) and general formula (3). Preferably, at least one of the at least one compound selected from general formula (2) and general formula (3) contains three Si-H functional groups, thereby forming a three-dimensional network structure with a certain crosslinking density.

[0216] According to a specific embodiment, the raw materials for components A and B of the silicone rubber-based nonlinear conductive insulating composite material composition include: 10-100 parts by weight, preferably 20-65 parts by weight, more preferably 25-35 parts by weight, of at least one compound of general formula (1) relative to 100 parts by weight of the base rubber; 0.4-10 parts by weight, preferably 1-5 parts by weight, of at least one compound selected from general formula (2) and general formula (3); 0.002-0.02 parts by weight, preferably 0.003-0.01 parts by weight, of catalyst; and 0.02-1 parts by weight, preferably 0.05-0.5 parts by weight, of inhibitor.

[0217] Step (4): Preparation of component B1

[0218] According to one embodiment, conductive filler E2, semiconductor nanoparticle material E3, and organic conductive additive F are dispersed into component B to obtain component B1 containing dispersed conductive filler E2, semiconductor nanoparticle material E3, and organic conductive additive F.

[0219] For example, 0.1-5 parts by weight of conductive material E2, 5-50 parts by weight of semiconductor nanoparticle material E3, and 0.5-10 parts by weight of organic conductive additive F are added to 30-100 parts by weight of component B.

[0220] The dispersion can be performed using a three-roll mill, for example, the dispersion operation can be performed 3-5 times, and the distance between the three rollers can be adjusted to 1-10 μm.

[0221] Step (5): Obtaining the silicone rubber-based nonlinear conductive insulating composite material composition

[0222] According to one embodiment, component A and component B1 are mixed evenly and then degassed under vacuum to obtain the silicone rubber-based nonlinear conductive insulating composite material composition according to the present invention.

[0223] The present invention also relates to a silicone rubber-based nonlinear conductive insulating composite material obtained by cross-linking and curing the silicone rubber-based nonlinear conductive insulating composite material composition. The cross-linking and curing is achieved by methods conventional in the art.

[0224] The present invention also relates to articles obtained from silicone rubber-based nonlinear conductive insulating composite material compositions according to the present invention or silicone rubber-based nonlinear conductive insulating composite materials according to the present invention.

[0225] According to one embodiment, the article is obtained by vulcanizing the silicone rubber-based nonlinear conductive insulating composite material composition. According to another embodiment, the article is obtained by temperature-curing vulcanization.

[0226] Depending on the end use, the silicone rubber-based nonlinear conductive insulating composite material composition can be made into the desired form, such as sheets, tubes, cable termination accessories such as stress cones, etc.

[0227] Preferably, the product may be selected from cable accessories specifically designed for high voltage direct current transmission, such as cable joint accessories or cable termination accessories, especially stress cones.

[0228] This vulcanization molding process is known in the art. Those skilled in the art can select a suitable molding method based on the application and form of the final product. For example, this molding can be performed by compression molding, hot pressing, etc.

[0229] According to one embodiment, the molded silicone rubber-based nonlinear conductive insulating composite material is vulcanized, for example, by performing a first-stage vulcanization and a second-stage vulcanization.

[0230] The present invention also relates to the use of the silicone rubber-based nonlinear conductive insulating composite material composition according to the invention or the silicone rubber-based nonlinear conductive insulating composite material according to the invention in the preparation of cable accessories, particularly for high voltage direct current transmission, such as cable joint accessories or cable termination accessories, especially stress cones.

[0231] The present invention also relates to the use of silicon-containing π-conjugated polymers, doped or undoped π-conjugated conductive polymers, organosilicon polymers with σ-π conjugation in the main chain, organic ionic liquids or mixtures thereof as additives, such as organic conductive additive F, in silicone rubber-based nonlinear conductive insulating composite material compositions.

[0232] According to one embodiment, the use can be achieved by adding the silicon-containing π-conjugated polymer, doped or undoped π-conjugated conductive polymer, organosilicon polymer with σ-π conjugation in the main chain, organic ionic liquid or mixtures thereof as described above to a silicone rubber-based nonlinear conductive insulating composite material composition, wherein the silicone rubber-based nonlinear conductive insulating composite material composition preferably contains at least one organopolysiloxane compound A, each molecule of which contains at least two alkenyl groups bonded to silicon atoms, preferably C2-C6 alkenyl groups; at least one organohydrogen-based polysiloxane compound B, each molecule of which preferably contains at least two hydrogen atoms bonded to the same or different silicon atoms; at least one catalyst C, containing at least one platinum group metal or compound; optionally, at least one organosilicon resin D; at least one reinforcing filler E1, preferably at least one silica; at least one conductive filler E2 and / or at least one semiconductor nanoparticle material E3, preferably at least one conductive filler E2 and at least one semiconductor nanoparticle material E3; optionally, at least one crosslinking inhibitor G.

[0233] Preferably, the silicon-containing π-conjugated polymer, doped or undoped π-conjugated conductive polymer, organosilicon polymer with σ-π conjugation in the main chain, organic ionic liquid, or mixtures thereof are as defined above. More preferably, the silicone rubber-based nonlinear conductive insulating composite material composition is as defined above. The relevant descriptions above regarding the silicone rubber-based nonlinear conductive insulating composite material composition and other related topics also apply to this use. Attached Figure Description

[0234] Figure 1 A line graph showing the volume resistivity of the nonlinear conductive insulating composite material according to Example 1 as a function of electric field strength at different temperatures is shown.

[0235] Figure 2 A line graph showing the volume resistivity of the nonlinear conductive insulating composite material according to Example 2 as a function of electric field strength at different temperatures is shown.

[0236] Figure 3 A line graph showing the volume resistivity of the nonlinear conductive insulating composite material according to Example 3 as a function of electric field strength at different temperatures is shown.

[0237] Figure 4 A line graph showing the volume resistivity of the nonlinear conductive insulating composite material according to Example 8 as a function of electric field strength at different temperatures is shown.

[0238] Figure 5 The current decay diagrams of the nonlinear conductive insulating composite material according to Example 4 are shown at room temperature and under an electric field of 2 kV / mm.

[0239] Figure 6The current decay diagrams of the nonlinear conductive insulating composite material according to Example 5 are shown at room temperature and under an electric field of 2 kV / mm. Detailed Implementation

[0240] The invention will now be illustrated by the following non-limiting embodiments.

[0241] Example

[0242] 1. Materials and equipment used in the embodiments:

[0243] Unless otherwise stated, the chemical reagents used in the following examples are all commercially available reagents (such as chemically pure or analytically pure reagents), the technical means used are all well-known to those skilled in the art, the equipment used are all commercially available equipment, and the operations performed using them are routine operations well-known to those skilled in the art.

[0244] -Preparation of the organic conductive additives used in the examples:

[0245] • Organic conductive additive 1: [9,9'-bis(triphenylsilyl)-9hydro,9'hydro-3,3'-biscarbazole] compound

[0246] According to the synthetic method disclosed in Materials Science and Engineering B, Volume 261, 114662, 2020, 2.2 Synthesis: 9,9'-Bis(triphenylsilyl)-9H,9'H-3,3′-bicarbazole (BiCzSiPh 3), a compound containing a carbazole group, [9,9'-bis(triphenylsilyl)-9H,9'H-3,3'-biscarbazole], was prepared as an organic conductive agent.

[0247] At room temperature, a mixture of carbazole and ferric chloride (molar ratio 1:4) was placed in chloroform solvent and stirred for more than 1 hour. After the reaction was completed, the solvent was removed by rotary evaporation. After vacuum drying at 40 °C, the crude product was crystallized in a mixture of isopropanol / dimethylformamide to obtain 3,3'-dicarbazole. The 3,3'-dicarbazole prepared above was dissolved in tetrahydrofuran and treated at -40 °C with tetramethylethylenediamine and 1.7M n-butyllithium (molar ratio of the three substances being 1:3:2.2, respectively) to obtain a lithium-salted intermediate. After stirring for 30 minutes, the mixture was quenched at -70 °C with triphenylchlorosilane (molar ratio of 2.2:1 to 3,3'-dicarbazole). The reaction mixture was stirred overnight. The obtained target compound was a white amorphous powder after washing with methanol. The molecular formula of the product is C 60 H 44N₂Si₂ was produced in approximately 22% yield. Elemental analysis showed the following composition: C: 84.82%, H: 5.21%, N: 3.31%, Si: 6.65%. The product is soluble in CDCl₃. 1 The 1H NMR spectrum showed singlets at δ = 6.71, δ = 7.02, δ = 7.21, δ = 7.34, δ = 7.49, δ = 7.70, δ = 8.12, and δ = 8.38, consistent with literature reports. The structural formula is shown below:

[0248]

[0249] [9,9'-bis(triphenylsilyl)-9-hydro,9'-hydro-3,3'-biscarbazole] compound

[0250] • Organic conductive additive 2: α,ω-divinyl poly(dimethyl-co-[4-(1-phenylbenzimidazol-2-yl)biphenyl]methyl)siloxane

[0251] Using p-bromophenylmethyldichlorosilane (CAS: 18141-19-0) and dimethyldichlorosilane (CAS: 75-78-5) as raw materials, and dimethylvinylchlorosilane (CAS: 1719-58-0) as a capping agent, the solutions were dissolved in sufficient tetrahydrofuran solution and stirred until homogeneous. An appropriate amount of hydrochloric acid aqueous solution (HCl content between 1.0-2.0 mol.%) was added, and the reaction was maintained at room temperature for more than 3 days under vigorous stirring. After standing and separation, the organic layer was washed with a dilute alkaline solution until neutral, then heated to 50°C and dried under vacuum by rotary evaporation to obtain a polysiloxane (α,ω-divinyl poly(dimethyl-co-p-bromopropylmethyl)siloxane) containing p-bromophenyl side groups.

[0252] According to the method for introducing conjugated side chain groups reported in section 2.2.3 of Synthesis Procedures in Organic Electronics, Volume 55, 117-125, 2018, using the above polymer as raw material, (4-(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl)boronic acid (CAS: 952514-79-3, with a molar ratio of 1.2:1 to the p-bromophenyl contained in the above polymer) and trans-dichlorobis(triphenylphosphine)palladium(II) as catalyst (CAS: 13965-03-2, Pd content 15.1%) were added sequentially, with toluene as solvent. The mixture was stirred under nitrogen atmosphere for 30 minutes until the solution became clear. Then, a 2M aqueous solution of Na₂CO₃ was added to the reaction mixture and the temperature was raised to 105°C. The reaction mixture was reacted for at least 10 hours with vigorous stirring. After cooling to room temperature, the reaction solution was extracted twice with dichloromethane. The combined organic layers were washed with water and dried with anhydrous Na₂SO₄. After filtration, the organic layers were rotary evaporated to remove the solvent. Then, the crude product (petroleum ether:dichloromethane = 1:1, v / v) was purified by column chromatography on a silica gel column. A white gel-like product was given, the structural formula of which is shown below. The yield was approximately 79.3%, and the molecular weight was M. w =23600 g / mol, molecular weight distribution PDI=2.03, elemental analysis results show that the contents of each element are C: 59.41, H: 6.49, N: 4.38, Si: 19.03, O: 10.68; the product is soluble in CDCl3. 1 The 1H NMR spectrum showed multiplets at δ = 0.13, δ = 4.92–6.18, δ = 7.27–7.32, δ = 7.37, δ = 7.42–7.54, δ = 7.70–7.79, and δ = 7.89–8.07, proving that π-conjugated structural groups were effectively grafted onto the polysiloxane side chains.

[0253]

[0254] In this example, the obtained polymer has n=37 and m=121.

[0255] The values ​​of n and m can be adjusted within the following ranges: n = 1-200, m = 0-500.

[0256] • Organic conductive additive 3: Poly(hexylthiophene) silicone oil dispersion (PHTSi)

[0257] Thin sheets of undoped polyhexylthiophene (PHT)(M w=36000 g / mol, CAS:104934-50-1) dissolved in chloroform. After heating and stirring for about 1 hour, a homogeneous solution was obtained, which was then slowly poured into a vinyl-terminated linear polydimethylsiloxane (CAS:68083-19-2, viscosity 20000 mPa·s, vinyl unit mass content: 0.10%) under stirring, wherein the ratio of PHT to polysiloxane could be adjusted to 20% by weight. The above mixture was placed in a ventilated device to allow the chloroform to evaporate slowly, resulting in a polysiloxane containing undoped PHT. This commercially available PHT... 1 The absorption peaks at δ = 1.72 and 2.80 in the 1H NMR spectrum are methylene peaks of alkyl groups connected to the aromatic ring. The single peak at δ = 6.98 instead of multiple chemical shifts proves that the thiophene units are orderedly connected.

[0258] • Organic conductive additive 4: Camphor sulfonic acid-doped polyaniline (PANI)

[0259] Aniline was dissolved in toluene, and camphor sulfonic acid and ammonium persulfate were dissolved in deionized water. The two solutions were then carefully poured into a beaker to form a stable phase-separated solution. Aniline began to polymerize at the interface between the two phases and gradually diffused into the aqueous phase. The reaction was completed after approximately 24 hours, yielding a dark green doped polyaniline. After repeated washing and drying with deionized water, a powdered conductive polymer was obtained. Infrared spectroscopy revealed peaks at 1581 and 1500 cm⁻¹. -1 Characteristic absorption peaks (-C=N, benzene ring C=C), 1300 cm⁻¹ -1 The characteristic absorption peak of CN, 1156 cm⁻¹ -1 The presence of polyaniline was confirmed by the characteristic absorption peaks of the benzene ring CH, at 1745, 1058, 710, and 604 cm⁻¹. -1 These are the characteristic absorption peaks of camphor sulfonic acid.

[0260] This yields a dark green camphor sulfonic acid-doped polyaniline (PANI) powder, which serves as a conductive additive.

[0261] • Organic conductive additive 5: PsiPS-doped polypyrrole (PPy)

[0262] Preparation method of anionic polysiloxane electrolyte-doped polypyrrole (PPy): According to the method reported in Chinese Journal of Polymer Science, Volume 14, 368, 1996, (3-chloropropyl)diethoxymethylsilane (molar ratio to sodium sulfite 1:1.2) was added to an aqueous solution of sodium sulfite and ethanol. The mixture was stirred at 80°C for 22 hours, cooled to room temperature, and the extract was filtered. After evaporating the solvent and drying under vacuum, ethoxylated-terminated oligomeric (sodium propyl sulfonate methylsiloxane) (M...) was obtained as a white solid.w =8000 g / mol). The product dissolves in D2O. 1 The ¹H NMR spectrum showed a singlet at δ = 0.19 and three multiplets at δ = 0.75, 1.82, and 2.93, confirming the presence of propylsulfonic acid groups. This product was treated with a cation exchange resin and the resin was removed by filtration. The solution was then concentrated at 90°C for 24 hours to obtain a crude product. Further purification by dialysis removed small-molecule inorganic salts, yielding a brown, viscous liquid form of ethoxylated terminal oligomeric (propylsulfonic acid methylsiloxane) PsiPS.

[0263] Electrolytic polymerization of pyrrole monomers in an aqueous solution of PsiPS was carried out for 15 min at a constant current using a two-electrode system. After polymerization, PsiPS-doped polypyrrole (PPy) was deposited on a stainless steel working electrode. The thin film product was peeled off from the electrode surface and washed with water and ethanol. It was then dried under vacuum at 50 °C for 12 h to obtain a powdered conductive additive. Its conductivity was measured to be 8.7 S cm⁻¹. -1 .

[0264] Organic conductive additive 6: Polydimethylsiloxane phthalocyanine

[0265] An isotropic liquid phthalocyanine compound with peripheral polydimethylsiloxane oligomer substitution effect (structure shown below) was prepared according to the synthetic method reported in Chemical Communications, 7, 615-616, 2001. Allylphenoxyphthalonitrile was prepared via a nitroaromatic substitution reaction using 4-nitrophthalonitrile (CAS: 31643-49-9) and 2-allylphenol (CAS: 1745-81-9) as starting materials. Then, butyl-terminated hydrosilyl polydimethylsiloxane oligomers (degree of polymerization n = 9) were synthesized by anionic ring-opening polymerization using hexamethylcyclotrisiloxane as a starting material and butyllithium as an initiator. This hydrogen-containing oligomer is coupled with allylphenoxyphthalonitrile via a hydrosilylation reaction to yield an allylphenoxyphthalonitrile-PDMS adduct. Further, in the presence of lead oxide, a cyclotetramerization reaction occurs to generate polydimethylsiloxane phthalocyanine, as shown below, which is then used as an organic conductive additive. The infrared spectra are at 2961, 1612, 1501, 1251 (SiCH3), 1090, 1012 (SiOSi), and 797 (SiC) cm⁻¹. -1 Characteristic absorption peaks were observed, consistent with data reported in the literature.

[0266]

[0267] Polydimethylsiloxane phthalocyanine

[0268] • Organic conductive additive 7: The cationic form is 1-{dimethyl[(trimethylsilyl)oxy]silyl}methyl-3-methylimidazolium [SiOSiIm] + Furthermore, the anion is hexafluorophosphate [PF6]. - ionic liquids

[0269] A silicon-containing low-viscosity ionic liquid was prepared according to the synthetic method reported in Chemical Physics, 472, 128-134, 2016. 1-Methylimidazole (CAS: 616-47-7) underwent a quaternization reaction with a siloxane terminally containing a chlorine atom. Using chloromethylpentamethyldisiloxane (CAS: 17201-83-1) as the starting material and acetonitrile as the solvent, the reaction was carried out at 80°C under argon protection for 48 h to obtain the corresponding chloride salt. After washing with ethyl acetate and recrystallization, an intermediate was obtained. This intermediate was then subjected to ion exchange to obtain the target ionic liquid, namely, 1-{dimethyl[(trimethylsilyl)oxy]silyl}methyl-3-methylimidazole [SiOSiIm] with a cation of 1-{dimethyl[(trimethylsilyl)oxy]silyl}methyl-3-methylimidazole [SiOSiIm]. + Furthermore, the anion is hexafluorophosphate [PF6]. - Ionic liquids.

[0270] -Preparation of the base material used in the examples:

[0271] Preparation of the base adhesive: In a planetary mixer, 40 parts by weight of vinyl-terminated silicone oil (CAS: 68083-19-2, vinyl unit content 0.085% by mass) with a viscosity of 55000 mPa·s and 26 parts by weight of BET specific surface area of ​​300 m² were mixed. 2 / g of fumed silica (CAS: 112945-52-5, untreated surface, particle size <10nm, SiO2 content >99.8% by weight), 6 parts of hexamethyldisilazane (CAS: 999-97-3), 0.05 parts of tetramethyldivinylsilazane (CAS: 7691-02-3), and 2 parts of deionized water were mixed thoroughly at 80°C under an inert atmosphere for 1.5 hours. Then, the temperature was raised to 140°C and vacuumed for 3 hours, maintaining the temperature at 160°C during vacuuming. The mixture was then cooled to 125°C, and 20 parts of methyl vinyl silicone oil with a viscosity of 60000mPa·s (CAS: 68083-19-2, vinyl unit content 0.080% by weight) were added and stirred until homogeneous to obtain liquid silicone rubber base.

[0272] Preparation of components A and B: 100 parts of the base adhesive, 18 parts of terminal vinyl silicone oil with a viscosity of 20000 mPa·s (CAS: 68083-19-2, vinyl unit content of 0.10 wt%), 18 parts of terminal vinyl silicone oil with a viscosity of 60000 mPa·s (CAS: 68083-19-2, vinyl unit content of 0.080 wt%), 5 parts of side-chain vinyl silicone oil with a viscosity of 1000 mPa·s (CAS: 68083-18-1, vinyl unit content of 2.30 wt%), and 0.02 parts of caster-type catalyst (CAS: 68478-92-2, platinum content: 10 wt%) were stirred and dispersed in a planetary mixer for 35 min. After mixing evenly, the mixture was degassed under vacuum to obtain component A.

[0273] The above-mentioned 100 parts of base rubber, 15 parts of terminal vinyl silicone oil with a viscosity of 20000 mPa·s (CAS: 68083-19-2, vinyl unit content of 0.10 wt%), 3 parts of side-chain vinyl silicone oil with a viscosity of 1000 mPa·s (CAS: 68083-18-1, vinyl unit content of 2.30 wt%), 1.5 parts of hydrogen-containing silicone oil with a hydrogen content of 0.7 wt% and containing Si-H at both ends and side chains (CAS: 69013-23-6, viscosity: 25 mPa·s), 1.5 parts of terminal hydrogen-containing silicone oil with a hydrogen content of 0.2 wt% (CAS: 70900-21-9, viscosity: 8.5 mPa·s), and 7.5 parts of vinyl content of 3.0 wt% and M W The following is a mixture of 10,000 g / mol MQ silicone resin (CAS: 68584-83-8) (pre-dissolved in 50% vinyl-terminated silicone oil (CAS: 68083-19-2) with a viscosity of 20,000 mPa·s, totaling 15 parts with the silicone oil), and 0.1 parts 1-ethynyl-1-cyclohexanol. The mixture is stirred and dispersed in a planetary mixer for 35 min, and after being mixed evenly, it is degassed under vacuum to obtain component B.

[0274] Component AB serves as the base material for the silicone rubber-based nonlinear conductive insulating composite material of the present invention.

[0275] - Semiconductor nanoparticle materials used in the embodiments:

[0276] Barium titanate: purchased from Shandong Guoci Functional Materials Co., Ltd., HBT-010, with an average particle size of 100 nm and a BET specific surface area of ​​10.30 m². 2 / g.

[0277] Nano ZnO: Purchased from Zhejiang Yamei Nanotechnology Co., Ltd., AM-ZnO-001-3, with an average particle size of 100nm and a BET specific surface area of ​​77m². 2 / g.

[0278] SiC whiskers: Purchased from Beijing Deco Island Gold Technology Co., Ltd., nano-silicon carbide (oleophilic), average particle size between 50-100nm, BET specific surface area of ​​30m². 2 / g.

[0279] Nano-titanium dioxide: Purchased from Shanghai Huijingya Nanomaterials Co., Ltd., anatase nano-titanium dioxide, with an average particle size of 20nm and a BET specific surface area of ​​120m². 2 / g.

[0280] 2. Example

[0281] Example 1:

[0282] In a three-roll mill, 9.00 parts by weight of barium titanate as a semiconductor nanoparticle material, 0.07 parts by weight of carbon nanotubes (single-walled carbon nanotubes, specifications: diameter 1-2 nm, length 4-5 μm, untreated surface) and 2.01 parts by weight of organic conductive additive 1 were added to 44.46 parts by weight of component B. The mixture was passed through the three-roll mill four times, with the roller spacing adjusted to below 10 μm. Component B1, containing dispersed semiconductor nanoparticle material, conductive filler, and organic conductive additive, was obtained.

[0283] Component B1 was added to 44.46 parts by weight of component A, dispersed evenly, and degassed to obtain a silicone rubber-based nonlinear conductive insulating composite material composition.

[0284] Example 2-10

[0285] The silicone rubber-based nonlinear conductive insulating composite material compositions of Examples 2-10 were prepared in the same manner as in Example 1, according to the various components and phase application amounts shown in Table 1.

[0286] Table 1: The amounts of various components and phases used in the compositions of the examples, wherein the amounts are expressed in parts by weight.

[0287] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Component B 44.46 37.45 43.96 39.46 40.95 37.45 44.55 36.45 39.95 36.20 Component A 44.46 37.45 43.96 39.46 40.95 37.45 44.55 36.45 39.95 36.20 carbon nanotubes 0.07 0.10 0.08 0.08 0.10 0.10 0.10 0.10 0.10 0.10 Organic conductive additive 1 2.01 3.00 Organic conductive additive 2 5.00 8.00 Organic conductive additive 3 6.00 5.00 Organic conductive additive 4 2.80 Organic conductive additive 5 7.00 Organic conductive additive 6 8.00 Organic conductive additive 7 2.50 Barium titanate 9.00 10.00 12.00 Nano ZnO 20.00 20.00 25.00 SiC whiskers 6.00 8.00 Nano titanium dioxide 18.00 20.00

[0288] 3. Performance Testing:

[0289] • Preparation of sample pieces

[0290] Sample pieces of 2 mm and 0.5 mm were prepared in a molding press. The molding press temperature was 120℃, the pressure was 5 MPa, and the vulcanization time was 10 min, during which air bubbles were removed. The prepared sample pieces were then suspended in an oven for two-stage vulcanization at 200℃ for 4 h. Throughout the sample preparation process, the surface of the sample pieces was kept clean, bubble-free, smooth, and flat.

[0291] Before testing, the sample pieces were conditioned for 16 hours in a constant temperature and humidity environment of 23±2℃ and 50±10%RH. In this invention, a 0.5mm sample piece was used for electrical performance testing and a 2mm sample piece was used for mechanical performance testing.

[0292] Volume resistivity

[0293] The volume resistivity was tested according to GB / T 40719-2021. A 0.5mm silicone rubber sample sheet was cut to a size that could cover the annular electrode. The thickness of the sample sheet was measured at no less than three points, and the average value was taken. The thickness fluctuation of a group of sample sheets should not exceed 10% of the average value. The number of sample sheets should be 2-3.

[0294] Connect the volume resistivity meter to the volume resistivity measuring electrodes. When placing the protected electrode (main electrode) and the unprotected electrode (ring electrode), ensure that the entire electrode area is in close contact with the sample. Apply a voltage of 1 kV, and after 1 minute, begin measuring the current between the protected and unprotected electrodes. Calculate the corresponding volume resistivity based on the corresponding volume resistivity value.

[0295] • The relative permittivity and dielectric loss tangent are tested according to standard GB / T 31838.6-2021, with a voltage of 1kV, a test temperature of 30-90℃, and a humidity of 10-50%RH.

[0296] • Breakdown field strength was tested according to standard GB / T 1408.1-2016.

[0297] Mechanical properties were tested according to the following standards: elongation at break, tensile strength, tear strength (ASTM D412-1998(2002)), hardness (GB / T6031-2017), and density (GB / T533-2008).

[0298] Table 2 below shows the mechanical and electrical properties of the silicone rubber-based nonlinear conductive insulating composite material obtained from the compositions of the embodiments of the present invention.

[0299] Table 2: Mechanical and electrical properties of materials obtained according to embodiments of the present invention

[0300]

[0301] As can be seen from the test results in Table 2, in general, the conductivity of the silicone rubber-based nonlinear conductive insulating composite material according to the present invention can be effectively adjusted within a large range, the breakdown voltage meets the application requirements, and the mechanical properties are good. It can be seen that the tensile strength of all sample examples is not less than 5.0 MPa and the elongation at break is not less than 400%, which meets the requirements for the use of nonlinear conductive insulating composite materials.

[0302] Figures 1 to 4 It is a line graph showing the relationship between volume resistivity and electric field distribution of nonlinear conductive insulating composite materials at different temperatures.

[0303] like Figure 1 As shown, for the material in Example 1, compared with 80°C at 30°C, its volume resistivity changes by 21.6 times under a 10kV / mm electric field and by 14.9 times under a 20kV / mm electric field.

[0304] like Figure 2 As shown, for the material in Example 2, compared with 80°C at 30°C, its volume resistivity changes by 19.2 times under a 10kV / mm electric field and by 9.6 times under a 20kV / mm electric field.

[0305] like Figure 3 As shown, for the material in Example 3, compared with 80°C at 30°C, its volume resistivity changes by 14.6 times under a 10kV / mm electric field and by 11.8 times under a 20kV / mm electric field.

[0306] like Figure 4 As shown, for the material in Example 8, compared with 80°C at 30°C, its volume resistivity changes by 2.9 times under a 10kV / mm electric field and by 1.7 times under a 20kV / mm electric field.

[0307] By comparing and analyzing the experimental results of the above four materials, it can be seen that the volume resistivity of the silicone rubber-based nonlinear conductive insulating composite material of the present invention at 80℃ and the volume resistivity at 30℃ can be adjusted within a large range, which well meets the different trends of resistivity variation with temperature or electric field of different cable insulation materials.

[0308] Depend on Figures 1 to 4 It can also be seen that the volume resistivity of the silicone rubber-based nonlinear conductive insulating composite material prepared according to the present invention shows a significant decreasing trend with increasing electric field strength at two different temperatures: 30℃ and 80℃. Comparing the resistivity changes at electric field strengths of 10kV / mm and 20kV / mm, it can be found that the decrease is greater at 30℃, while the decrease is smaller at the higher temperature of 80℃.

[0309] Under the same electric field strength, the volume resistivity decreases with increasing temperature; however, the decrease is more pronounced at lower electric field strengths. These results indicate that under low-temperature and low-electric-field conditions, the silicone rubber-based nonlinear conductive insulating composite material of this invention exhibits a higher rate of change with both conditions; under high-temperature and high-electric-field conditions, the dependence of the silicone rubber-based nonlinear conductive insulating composite material of this invention on both conditions decreases, which is consistent with the trend of cross-linked polyethylene (XLPE).

[0310] Compared to XLPE, the resistivity of conventional silicone rubber materials is less affected by temperature and electric field, which makes its volume resistivity lower than that of XLPE even at room temperature. However, as temperature or electric field strength increases, the volume resistivity of XLPE can decrease by up to three orders of magnitude, which is much lower than that of silicone rubber materials. The above differences lead to charge accumulation at the interface of the two types of dielectric materials, which is the main cause of cable accessory failure.

[0311] The silicone rubber-based nonlinear conductive insulating composite material prepared according to the present invention overcomes the problems of the prior art. Furthermore, Figures 1 to 4 The materials in the four embodiments shown exhibit significantly different dependence coefficients on electric field strength and temperature due to variations in their specific formulations. Within the scope of this invention, by appropriately compounding compositional components such as conductive additives, semiconductor nanoparticles, and conductive fillers, the obtained nonlinear conductive insulating composite material can exhibit different volume resistivity variation trends under the coupling effects of temperature and electric fields. This allows it to be adapted to XLPE or other high-voltage DC cable insulation materials with different properties, thereby reducing interfacial charge accumulation and homogenizing the electric field distribution of cable accessories.

[0312] Depend on Figure 5 and Figure 6 It can be seen that the nonlinear conductive insulating composite materials prepared according to Examples 4 and 5 exhibit a faster current decay rate and a larger decay amplitude, which is very similar to the polarization current decay curve of XLPE. Previously reported conventional silicone rubber materials, due to their low charge injection threshold field, can inject a large amount of space charge, resulting in longer charge migration and dissipation times; moreover, composite materials formed by polymers and inorganic fillers exhibit interfacial polarization and other slow polarization effects, requiring an extremely long time (30 min) for the current to reach a steady-state convergence under low external electric fields. However, in this invention, through the combination of the components of the composition, especially the introduction of the organic conductive additive according to the invention, interfacial polarization can be eliminated, enabling the prepared silicone rubber-based nonlinear conductive insulating composite material to exhibit a faster current decay rate and reach convergence in a shorter time under low electric fields.

[0313] Without departing from the spirit of this invention, those skilled in the art can obtain different nonlinear conductive insulating composite materials by selecting and combining key raw materials, adjusting their dosage ratios, or substituting equivalents for their elements. These composite materials exhibit different volume resistivity variations with electric field strength and temperature, thus meeting diverse application requirements. Therefore, this invention is not limited to the specific embodiments disclosed as the best mode for illustrating the invention.

Claims

1. A silicone rubber-based nonlinear conductive insulating composite material composition, comprising: - At least one organopolysiloxane compound A, each molecule of which contains at least two alkenyl groups bonded to silicon atoms, preferably C2-C6 alkenyl groups. - At least one organohydrogen-based polysiloxane compound B, which preferably contains at least two hydrogen atoms per molecule bonded to the same or different silicon atoms. - At least one catalyst C, comprising at least one platinum group metal or compound. -Optionally, at least one silicone resin D, - At least one reinforcing filler E1, preferably at least one silica. - At least one conductive filler E2 and / or at least one semiconductor nanoparticle material E3, preferably at least one conductive filler E2 and at least one semiconductor nanoparticle material E3. -At least one organic conductive additive F, -Optionally, at least one crosslinking inhibitor G.

2. The silicone rubber-based nonlinear conductive insulating composite material composition according to claim 1, characterized in that, Catalyst C is a platinum-based catalyst, preferably selected from chloroplatinic acid, an alcoholic solution of chloroplatinic acid, a platinum complex catalyst, a coated platinum catalyst, or a mixture thereof.

3. The silicone rubber-based nonlinear conductive insulating composite material composition according to any one of the preceding claims, characterized in that, The conductive filler E2 is selected from carbon nanotubes, graphene, superconducting carbon black, nanographite sheets, carbon fibers, Mxenes or mixtures thereof, with carbon nanotubes being preferred.

4. The silicone rubber-based nonlinear conductive insulating composite material composition according to any one of the preceding claims, characterized in that, The semiconductor nanoparticle material E3 is selected from alumina, antimony tin oxide, cerium oxide, copper oxide, indium oxide, indium tin oxide, iron oxide, tin oxide, titanium dioxide, zinc oxide, chromium oxide, magnesium oxide, manganese oxide, molybdenum oxide, silicon carbide, copper calcium titanate, lead titanate, strontium titanate, barium titanate, barium strontium titanate, aluminum nitride, lead zirconate titanate, or mixtures thereof, and is preferably selected from titanium dioxide, silicon carbide, barium titanate, zinc oxide, or mixtures thereof.

5. The silicone rubber-based nonlinear conductive insulating composite material composition according to any one of the preceding claims, characterized in that, The organic conductive additive F is selected from silicon-containing π-conjugated polymers, doped or undoped π-conjugated conductive polymers, organosilicon polymers with σ-π conjugation in the main chain, organic ionic liquids and mixtures thereof.

6. The silicone rubber-based nonlinear conductive insulating composite material composition according to claim 5, characterized in that, The silicon-containing π-conjugated polymer is selected from silane compounds containing π-conjugated structural groups, linear polysiloxanes or branched polysiloxanes, stacked phthalocyanine polysiloxanes, polysiloxane-modified liquid phthalocyanines and mixtures thereof; preferably, the silicon-containing π-conjugated polymer is selected from silane compounds containing π-conjugated structural groups, linear polysiloxanes or branched polysiloxanes, and particularly preferably linear polysiloxanes containing side-chain π-conjugated structural groups.

7. The silicone rubber-based nonlinear conductive insulating composite material composition according to claim 5, characterized in that, The doped or undoped π-conjugated conductive polymer is selected from doped or undoped polyaniline (PANI), polypyrrole (PPy), polythiophene (PT) and related derivatives, such as poly(3,4-vinyldioxythiophene) (PEDOT) and polyhexylthiophene (PHT); preferably, the doped or undoped π-conjugated conductive polymer is selected from doped or undoped poly(3,4-vinyldioxythiophene) (PEDOT) and polyhexylthiophene (PHT), and particularly preferably PEDOT or PHT doped with sulfonated polysiloxane or other ionic polysiloxane.

8. The silicone rubber-based nonlinear conductive insulating composite material composition according to claim 5, characterized in that, The main chain of the σ-π conjugated organosilicon polymer is selected from polymers with alternating oligomeric silyl groups and π-electron groups, silicon-containing π-conjugated heterocyclic polymers, and polymers based on thiorrole (siloxane pentadiene); preferably, the main chain of the σ-π conjugated organosilicon polymer is a thiorrole polymer.

9. The silicone rubber-based nonlinear conductive insulating composite material composition according to claim 5, characterized in that, This organic ionic liquid comprises a combination of organic cations and inorganic or organic anions, wherein the organic cations are selected, for example, from imidazole cations, pyridine cations, quaternary ammonium cations, etc. The organic ionic liquid is selected from, for example, a tetrafluoroborate ion or a hexafluorophosphate ion, and / or a salt cation, a pyrrole cation, a piperidine cation, and / or an organic anion. Preferably, the organic ionic liquid is an ionic liquid-based polysiloxane, i.e., an ionic liquid containing polysiloxane segments.

10. The silicone rubber-based nonlinear conductive insulating composite material composition according to any one of the preceding claims, characterized in that, The composition comprises: -10-90% by weight, preferably 20-80% by weight, more preferably 30-70% by weight of at least one organopolysiloxane compound A, and / or -0.1-10.0 wt%, preferably 0.2-5.0 wt%, more preferably 0.5-3.0 wt%, of at least one organohydrogen-based polysiloxane compound B, and / or -0.001-1.000 wt%, preferably 0.002-0.500 wt%, more preferably 0.005-0.050 wt%, of at least one catalyst C, and / or -0.1-15.0 wt%, preferably 0.5-10.0 wt%, more preferably 1.0-5.0 wt% of at least one organosilicon resin D, and / or -5-50% by weight, preferably 10-40% by weight, more preferably 15-30% by weight of at least one reinforcing filler E1, and / or -0.001-1.000 wt%, preferably 0.01-0.50 wt%, more preferably 0.03-0.30 wt%, of at least one conductive filler E2, and / or -1-50% by weight, preferably 2-40% by weight, more preferably 5-30% by weight, of at least one semiconductor nanoparticle material E3, and / or -0.1-20.0% by weight, preferably 0.5-15.0% by weight, more preferably 1.0-10.0% by weight of at least one organic conductive agent F, and / or -0.002-1.000 wt%, preferably 0.005-0.500 wt%, more preferably 0.01-0.20 wt%, of at least one crosslinking inhibitor G. Based on the total weight of the composition, and the sum of the contents of each component in the composition is 100% by weight.

11. A silicone rubber-based nonlinear conductive insulating composite material obtained by crosslinking and curing the silicone rubber-based nonlinear conductive insulating composite material composition according to any one of the preceding claims.

12. An article obtained from the silicone rubber-based nonlinear conductive insulating composite material composition according to any one of claims 1-10 or the silicone rubber-based nonlinear conductive insulating composite material according to claim 11, wherein the article is preferably selected from cable accessories particularly used for high voltage direct current transmission, such as cable joint accessories or cable termination accessories, especially stress cones.

13. The use of the silicone rubber-based nonlinear conductive insulating composite material composition according to any one of claims 1-10 or the silicone rubber-based nonlinear conductive insulating composite material according to claim 11 for the preparation of cable accessories, particularly for high voltage direct current transmission, wherein the cable accessories are preferably cable joint accessories or cable termination accessories, especially stress cones.

14. Use of silicon-containing π-conjugated polymers, doped or undoped π-conjugated conductive polymers, organosilicon polymers with σ-π conjugation in their main chains, organic ionic liquids, or mixtures thereof as additives, such as organic conductive additive F, in silicone rubber-based nonlinear conductive insulating composite material compositions, wherein preferably, the silicon-containing π-conjugated polymers, doped or undoped π-conjugated conductive polymers, organosilicon polymers with σ-π conjugation in their main chains, and organic ionic liquids are as defined in any one of claims 6-9, and preferably, the silicone rubber-based nonlinear conductive insulating composite material compositions are as defined in any one of claims 1-4 and 10.

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