Two-component rubber composition, fire-blocking silicone rubber for nuclear power and use

Abstract

The present application belongs to the field of fireproof plugging materials, and provides a fireproof plugging silicone rubber for nuclear power through the design of a functional filler of layered double hydroxide loaded platinum catalyst (Pt@LDH) and scientific component distribution. The fireproof plugging silicone rubber for nuclear power solves the inherent contradiction that nuclear-grade materials are difficult to simultaneously achieve catalytic deactivation, storage stability and accident performance, and has the following advantages: long-term storage stability (>12 months); functional reliability under extreme accidents (high-efficiency ceramization, complete sealing, electrical insulation); nuclear-grade safety throughout the life cycle (resistant to high-dose irradiation, no harmful element activation).

Description

Technical Field

[0001] This invention belongs to the field of fireproof sealing materials, specifically relating to a two-component rubber composition, fireproof sealing silicone rubber for nuclear power plants, and its applications. Background Technology

[0002] In the containment vessel and cable penetration areas of nuclear power plants, fire-resistant sealing materials serve as the last physical barrier to ensure nuclear safety. These materials must maintain an elastic seal under normal operating conditions for up to 60 years, and rapidly transform into a dense, high-strength, electrically insulating ceramic barrier under extreme accident conditions (such as loss of coolant accident (LOCA), fire, or high-dose radiation) to absolutely prevent the leakage of radioactive materials and the spread of flames.

[0003] Currently, although nuclear-grade fire-stopping materials mostly employ a two-component addition-type silicone rubber system, the following long-standing technical challenges remain: Platinum catalysts are extremely sensitive to trace impurities (S, N, Sn, etc.) and are easily deactivated by filler impurities or radiation decomposition products. Adding excessive inhibitors to improve storage stability can lead to delayed or incomplete curing after application, creating safety hazards. Achieving flame retardancy requires the addition of large amounts of aluminum hydroxide / magnesium hydroxide, resulting in extremely high paste viscosity, poor extrusion, uneven mixing, and low-strength, easily cracked residual char formed at high temperatures. The thermal-mechanical-wet stresses generated by loss-of-coolant (LOCA) conditions (rapid cooling after high-temperature saturated steam impact) can easily cause material-substrate interface delamination, bulk blistering, or cracking, resulting in loss of sealing function. Various fillers introduced to achieve radiation resistance and neutron absorption functions, if coexisting with the platinum catalyst in the same component, may trigger slow side reactions, shortening the pot life; if separated, it is difficult to guarantee the uniformity and synergy of the functions after mixing. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention proposes a two-component rubber composition comprising component A and component B, with a mass ratio of component A to component B of 1:1. Based on a total mass of 50 parts by weight of component A, component A comprises 20-35 parts by weight of methyl vinyl silicone rubber, 0.5-3 parts by weight of methyl vinyl phenyl silicone rubber, 1-8 parts by weight of Pt@LDH, 0.5-2 parts by weight of a radiation-resistant additive, 4-25 parts by weight of a thermally conductive reinforcing additive, 1-6 parts by weight of a flame retardant, 1-4 parts by weight of a thixotropic agent, and 0.002-0.05 parts by weight of an inhibitor. In the methyl vinyl phenyl silicone rubber, the molar proportion of phenyl groups in the side groups of the silicone rubber molecule is 5-2%. 5 mol% LDH is an inorganic anionic layered double hydroxide compound, and the Pt@LDH includes an inorganic anionic layered double hydroxide compound and platinum nanoparticles supported on the inorganic anionic layered double hydroxide compound; based on a total mass of 50 parts by mass of component B, component B includes 20-35 parts by mass of methyl vinyl silicone rubber, 0.5-3 parts by mass of methyl vinyl phenyl silicone rubber, 0.5-3 parts by mass of hydrogen-terminated silicone oil, 2-6 parts by mass of neutron absorber, 10-25 parts by mass of structural filler and 1-4 parts by mass of thixotropic agent; in components A and B, the molar ratio of vinyl groups in methyl vinyl silicone rubber and methyl vinyl phenyl silicone rubber to active hydrogen in hydrogen-terminated silicone oil is 1:(1.1-1.5).

[0005] In one or more embodiments, the methyl vinyl silicone rubber has a vinyl content of 0.1-0.3 mol% of all organic side groups.

[0006] In one or more embodiments, in component A, the radiation-resistant additive is selected from one or more of nano-cerium oxide, nano-yttrium oxide, and 2,6-di-tert-butyl-4-methylphenol.

[0007] In one or more embodiments, in component A, the thermal conductivity enhancing agent is selected from one or more of α-alumina, magnesium oxide, aluminum nitride, and silicon carbide.

[0008] In one or more embodiments, in component A, the flame retardant is selected from one or more of zinc borate, aluminum hydroxide, and magnesium hydroxide.

[0009] In one or more embodiments, in component A, the thixotropic agent is selected from one or more of hydrophobic fumed silica, organobentonite, and polyamide wax.

[0010] In one or more embodiments, in component A, the inhibitor is selected from one or both of 1-ethynyl-1-cyclohexanol and 2-methyl-3-butyn-2-ol.

[0011] In one or more embodiments, the hydrogen content of the hydrogen-terminated silicone oil in component B is 0.1%-0.5%.

[0012] In one or more embodiments, in component B, the neutron absorber is selected from one or more of hexagonal boron nitride, surface-modified B4C, gadolinium oxide, and boric acid.

[0013] In one or more embodiments, in component B, the structural filler is selected from one or more of α-alumina, fumed silica, and silica powder; preferably, the α-alumina has a D... 50 It is 0.1-1μm.

[0014] In one or more embodiments, in component B, the thixotropic agent is selected from one or more of hydrophobic fumed silica, organobentonite, and polyamide wax.

[0015] In one or more embodiments, in Pt@LDH, the LDH comprises divalent metal ions and trivalent metal ions, wherein the divalent metal ions are Mg. 2+ or Zn 2+ The trivalent metal ion is Al 3+ The molar ratio of the divalent metal ions to the trivalent metal ions is (2.5-3.5):1.

[0016] In one or more embodiments, the average particle size of Pt in Pt@LDH is 2-8 nm.

[0017] In one or more embodiments, the mass fraction of Pt in Pt@LDH is 0.01%-1%.

[0018] In one or more embodiments, in Pt@LDH, the LDH is NO3. - type.

[0019] In one or more embodiments, the method for preparing the Pt@LDH includes: synthesizing NO3 with a Mg / Al molar ratio of 2.5-3.5 by co-precipitation. - Type LDH; P is loaded onto the LDH surface by thermal reduction or in-situ reduction.

[0020] Another aspect of the present invention provides a fireproof sealing silicone rubber for nuclear power plants, wherein the raw material for the fireproof sealing silicone rubber for nuclear power plants is the two-component rubber composition described in any embodiment of the present invention.

[0021] In one or more embodiments, the surface drying time of the two-component rubber composition is 10-60 min.

[0022] In one or more embodiments, the Shore A hardness of the fireproof sealing silicone rubber for nuclear power plants is 40-70.

[0023] In one or more embodiments, the tensile strength of the fireproof sealing silicone rubber for nuclear power plants is ≥4 MPa.

[0024] In one or more embodiments, the limiting oxygen index of the fire-resistant sealing silicone rubber for nuclear power plants is ≥26%.

[0025] In one or more embodiments, the fire-resistant silicone rubber for nuclear power plants is subjected to 5×10... 6 The tensile strength retention rate of Gy after γ-irradiation is ≥70%.

[0026] Another aspect of the present invention provides a method for preparing the fireproof sealing silicone rubber for nuclear power plants as described in any embodiment of the present invention, wherein the fireproof sealing silicone rubber for nuclear power plants is obtained by surface drying and curing of the two-component rubber composition described in any embodiment of the present invention.

[0027] In one or more embodiments, the curing temperature is 25±5℃ and the curing time is 24h.

[0028] In one or more embodiments, the curing temperature is 80-150°C and the curing time is 10-60 min.

[0029] Another aspect of the present invention provides the use of the two-component rubber composition described in any embodiment of the present invention and the fire-resistant sealing silicone rubber for nuclear power plants described in any embodiment of the present invention in ensuring nuclear safety.

[0030] Compared with the prior art, the fireproof sealing silicone rubber for nuclear power plants of the present invention has the following beneficial technical effects: 1. High catalytic efficiency: The Pt@LDH of this invention is supported by platinum, which is resistant to poisoning and has precise positioning. The nano-confinence and barrier protection effect of Pt@LDH are conducive to further improving its catalytic efficiency.

[0031] 2. Excellent ceramicization performance: The fireproof sealing silicone rubber for nuclear power plants of the present invention has a dense ceramic structure and a strength of ≥18MPa after ceramicization due to the in-situ synergy between the LDH skeleton and Pt catalytic carbonization.

[0032] 3. Good nuclear operating condition tolerance: Through the whole-system nuclear safety design concept of the present invention, the fireproof sealing silicone rubber for nuclear power plants can achieve a good seal after LOCA and is free of harmful elements.

[0033] In summary, the fireproof sealing silicone rubber for nuclear power plants of the present invention can simultaneously meet the following requirements: long-term storage stability (>12 months); functional reliability under extreme accidents (high-efficiency ceramization, complete sealing, electrical insulation); and nuclear-grade safety throughout the entire life cycle (resistance to high-dose irradiation, no activation by harmful elements). Attached Figure Description

[0034] Figure 1 The diagram shows the preparation process and structure of Pt@LDH, illustrating the catalyst immobilization method.

[0035] Figure 2 This document describes the formulation design and cross-linking network diagram of a two-component system.

[0036] Figure 3 This is a comparison of the advantages and disadvantages of the present invention with those of the prior art.

[0037] Figure 4 The image shows a radar chart of the product performance in Example 1. Detailed Implementation

[0038] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used herein are explained and defined in general terms below. Unless otherwise specified, all technical and scientific terms used herein have the common meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0039] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0040] In this document, the terms “contains,” “includes,” “containing,” and similar terms encompass the meanings of “basically composed of” and “composed of.” For example, when this document discloses “A contains B and C,” “A is basically composed of B and C” and “A is composed of B and C” should be considered as having been disclosed in this document.

[0041] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0042] Unless otherwise specified, percentages refer to mass percentages and proportions refer to mass ratios in this article.

[0043] In this article, the sum of the percentages of all components in the composition is 100%.

[0044] In this document, when describing embodiments or examples, it should be understood that it is not intended to limit the invention to those embodiments or examples. Rather, all alternatives, modifications, and equivalents of the methods and materials described herein are covered within the scope of this invention.

[0045] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0046] In this article, particle size (D) 50 The particle size distribution was obtained by laser particle size analyzer, in accordance with the GB / T 19077-2016 standard.

[0047] In this paper, the crystal structure of the layered double hydroxide was obtained by X-ray diffraction (XRD).

[0048] Two-component rubber composition

[0049] The two-component rubber composition of the present invention comprises component A and component B, wherein the mass ratio of component A to component B is 1:1; based on a total mass of 50 parts by mass of component A, component A comprises 20-35 parts by mass of methyl vinyl silicone rubber, 0.5-3 parts by mass of methyl vinyl phenyl silicone rubber, 1-8 parts by mass of Pt@LDH, 0.5-2 parts by mass of radiation-resistant additive, 4-25 parts by mass of thermal conductivity-enhancing additive, 1-6 parts by mass of flame retardant, 1-4 parts by mass of thixotropic agent, and 0.002-0.05 parts by mass of inhibitor; wherein, in the methyl vinyl phenyl silicone rubber, phenyl groups are present in the silicone rubber composition. The molar proportion of the side group is 5-25 mol%, and LDH is an inorganic anionic layered double hydroxide compound. The Pt@LDH includes an inorganic anionic layered double hydroxide compound and platinum nanoparticles supported on the inorganic anionic layered double hydroxide compound. Based on a total mass of 50 parts by mass of component B, component B includes 20-35 parts by mass of methyl vinyl silicone rubber, 0.5-3 parts by mass of methyl vinyl phenyl silicone rubber, 0.5-3 parts by mass of hydrogen-terminated silicone oil, 2-6 parts by mass of neutron absorber, 10-25 parts by mass of structural filler, and 1-4 parts by mass of thixotropic agent.

[0050] Methyl vinyl silicone rubber (hereinafter referred to as vinyl silicone rubber) is an organosilicon material with polysiloxane as the main chain, and its chemical name is polymethyl vinyl siloxane. It exhibits outstanding high and low temperature resistance (-55℃ to 300℃) and resistance to compression set. Product forms include white powder, colorless transparent liquid, and colloids with varying vinyl content. In some preferred embodiments, the methyl vinyl silicone rubber suitable for this invention has a vinyl content (i.e., vinyl percentage of all organic side groups) of 0.1-0.3 mol%, for example, 0.1 mol%, 0.15 mol%, 0.2 mol%, 0.25 mol%, 0.3 mol%, or any range between two such values.

[0051] Methyl vinyl phenyl silicone rubber, also known as phenyl silicone rubber, has phenyl groups in its molecular side chains, and its main chain is formed by copolymerization of dimethyldichlorosilane, methylphenyldichlorosilane, and methylvinyldichlorosilane. This material has a temperature resistance range of -100°C to 250°C. In some preferred embodiments, the molar percentage of phenyl groups in the side chains of the silicone rubber molecule (i.e., phenyl content) of the methyl vinyl phenyl silicone rubber suitable for use in this invention is 5-25 mol%, for example, 5 mol%, 5.5 mol%, 10 mol%, 10.5 mol%, 20 mol%, 24.5 mol%, 25 mol%, or any range between two values. Controlling the phenyl content within the above range helps to ensure radiation resistance while avoiding a decrease in its low-temperature elasticity.

[0052] The chemical formula of hydrogen-containing silicone oil is H-Si(CH3)2-O-[Si(CH3)2-O]. n -Si(CH3)2-H, CAS No. 70900-21-9, is a polysiloxane organosilicon intermediate with active Si-H bonds at the chain ends. In some preferred embodiments, the hydrogen content of the hydrogen-terminated silicone oil suitable for this invention is 0.1%-0.5%, for example, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, or any range between two values; wherein, the hydrogen content refers to the mass of active hydrogen (i.e., hydrogen in Si-H bonds) contained in a unit mass (usually 100 grams) of silicone oil.

[0053] In components A and B of the present invention, the molar ratio of vinyl groups in methyl vinyl silicone rubber to active hydrogen in hydrogen-terminated silicone oil is 1:(1.1-1.5) (e.g., 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5 or any range between two values). Controlling the molar ratio of vinyl groups in vinyl silicone rubber to active hydrogen in hydrogen-terminated silicone oil within the above range is beneficial to ensuring sufficient crosslinking during construction.

[0054] Radiation-resistant additives suitable for this invention include, but are not limited to, free radical scavengers such as nano-cerium oxide (CeO2), nano-yttrium oxide (Y2O3), and 2,6-di-tert-butyl-4-methylphenol (BHT). In some embodiments, when the radiation-resistant additive is nano-CeO2, the nano-CeO2 is preferably treated with a silane coupling agent. Controlling the mass fraction of the radiation-resistant additive to 0.5-2 parts is beneficial to avoid its agglomeration affecting mechanical properties while possessing significant radiation-resistant effects. In some embodiments, an appropriate amount of free radical scavenger can be introduced to synergize with nano-CeO2.

[0055] Thermal conductivity enhancing agents suitable for this invention include, but are not limited to, α-alumina, magnesium oxide, aluminum nitride, and silicon carbide, wherein the D of α-alumina is... 50 The preferred size is 0.1-1 μm. Adding thermal conductivity enhancers (such as α-alumina) can achieve both thermal conductivity and structural reinforcement.

[0056] Flame retardants suitable for use in this invention include, but are not limited to, zinc borate, aluminum hydroxide, and magnesium hydroxide. In some embodiments, the flame retardant is zinc borate, which can promote the formation of a glassy ceramic layer. When a thermal conductivity enhancing agent (e.g., α-alumina) is used in conjunction with zinc borate, it can synergistically promote the formation of the glassy ceramic layer. Controlling the mass fraction of the flame retardant to 1-6 parts helps avoid an imbalance in the ratio of thermal conductivity enhancing agent to flame retardant, which could lead to insufficient char strength or density.

[0057] The thixotropic agents suitable for use in this invention include, but are not limited to, hydrophobic fumed silica, organobentonite, and polyamide wax. Controlling the mass fraction of the thixotropic agent to 1-4 parts helps ensure the thixotropic properties of the paste and avoids sagging or extrusion difficulties.

[0058] Inhibitors applicable to this invention include, but are not limited to, 1-ethynyl-1-cyclohexanol and 2-methyl-3-butyn-2-ol. Controlling the mass fraction of the inhibitor to 0.002-0.05 parts helps ensure the application period and avoids excessively slow curing.

[0059] Neutron absorbers suitable for use in this invention include, but are not limited to, hexagonal boron nitride (h-BN), surface-modified B4C, gadolinium oxide (Gd2O3), and boric acid, wherein surface-modified B4C refers to B4C micropowder that has undergone surface silanization treatment.

[0060] The structural fillers suitable for this invention include, but are not limited to, α-alumina, fumed silica, and silica powder; wherein the D of α-alumina is... 50 The preferred size is 0.1-1 μm.

[0061] In this invention, Pt@LDH refers to the process of immobilizing platinum catalysts in nanoparticle form on a specific composition of inorganic anionic layered double hydroxide (LDH), creating a multifunctional filler with catalytic, flame-retardant, and ceramic-enhancing functions. LDH itself is an excellent high-temperature flame retardant and ceramic framework forming agent. Anchoring Pt nanoparticles to LDH layers not only utilizes the "barrier effect" of LDH to protect Pt from poisoning, but also achieves in-situ synergy between "LDH framework formation" and "Pt catalytic char formation" under fire conditions, generating a composite ceramic body with strength far exceeding that of conventional ones. This is the key to achieving "low filler, high performance".

[0062] In Pt@LDH, LDH comprises divalent and trivalent metal ions, wherein the divalent metal ion is preferably Mg. 2+ or Zn 2+ More preferably Mg 2+ The trivalent metal ion is Al 3+ The molar ratio of divalent metal ions to trivalent metal ions is (2.5-3.5):1, for example, 2.5:1, 3:1, 3.5:1 or any range between two values.

[0063] In Pt@LDH, the average particle size of Pt nanoparticles is 2-8 nm, such as 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm, 5 nm, 5.5 nm, 6 nm, 6.5 nm, 7 nm, 7.5 nm, 8 nm, or any range between two values.

[0064] In Pt@LDH, the mass fraction of Pt is 0.01%-1.0%, for example, 0.01%, 0.1%, 0.5%, 1%, or any range between two values.

[0065] In some preferred embodiments, LDH is NO3. - type.

[0066] In some implementations, Pt@LDH is prepared as follows: NO3 with a Mg / Al molar ratio of 2.5-3.5 was synthesized by co-precipitation method. - LDH was prepared by dispersing LDH in deionized water, adding chloroplatinic acid solution, and stirring at 60°C for 6 hours for ion exchange and adsorption. NaBH4 solution was then added for in-situ reduction, resulting in uniform anchorage of Pt nanoparticles (average particle size 2-8 nm) on the LDH surface. Surface modification was performed using a mixed silane of vinyltrimethoxysilane and 3-glycidoxypropyltrimethoxysilane to improve its dispersibility and interfacial bonding in the silicone rubber matrix, ultimately yielding the Pt@LDH of this invention with a Pt loading of 0.01-1 wt%.

[0067] In some implementations, Pt can be loaded onto the LDH surface via thermal reduction.

[0068] In this invention, the platinum catalyst must exist in a supported form within the hydrogen-free component (component A). Controlling the mass fraction of Pt@LDH to 1-8 parts helps to ensure catalytic efficiency, curing speed, and economy while avoiding a surge in system viscosity and a deterioration in workability.

[0069] In some embodiments, the surface drying time of the two-component rubber composition of the present invention is 10-60 min (tested according to GB / T 13477.5-2002), for example 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min or any range between two values, preferably 15-60 min.

[0070] It should be understood that, in order to meet the requirements of long-term stable storage, convenient on-site construction, and efficient accident response for flame-retardant two-component silicone rubber used in nuclear power, and to meet the stringent requirements of nuclear power safety for the entire life cycle of materials, the complete formulation of the two-component rubber composition of this invention must not contain any organic intercalating agents that are unstable under irradiation, or neutron-activating or toxic elements such as Co, Ni, Cd, and Pb.

[0071] This invention immobilizes a platinum catalyst in nanoparticle form on an inorganic anionic LDH, exhibiting resistance to poisoning and precise targeting. This results in Pt@LDH possessing catalytic flame retardancy and ceramic reinforcement functions, achieving atomic-level integration and synergy of functional units. Its two-component formulation utilizes NO3... - Type LDH, h-BN, and free of elements such as Co / Ni can systematically solve the unique safety problems of nuclear-grade materials, such as radiolysis gas generation, neutron shielding, and radioactive activation of organic intercalators.

[0072] Fireproof sealing silicone rubber for nuclear power plants

[0073] The raw material for the fireproof sealing silicone rubber for nuclear power plants of the present invention is the two-component rubber composition described in any embodiment of the present invention.

[0074] In some preferred embodiments, the fire-resistant sealing silicone rubber for nuclear power plants of the present invention has one or more of the following characteristics: Shore A hardness is 40-70 (tested according to GB / T 531.1-2008), such as 40, 42, 45, 49, 50, 55, 60, 65, 70 or any range between two values; Tensile strength ≥ 4 MPa (tested according to GB / T 528-2009), for example 4 MPa, 4.5 MPa, 5 MPa, 5.2 MPa, 5.3 MPa, 5.5 MPa, 6 MPa, 6.1 MPa, 6.5 MPa, 7 MPa; Limiting oxygen index (LOI) ≥ 26% (refer to GB / T 2406.2-2009 test), for example 26%, 28%, 30%; The UL-94 standard assigns a flame retardant rating of V-0. A continuous, dense ceramic shell can be formed within 10 minutes in an 800℃ muffle furnace; After 5×10 6 The tensile strength retention rate of Gy after γ-irradiation is ≥70% (tested according to GB / T 528-2009). After 5×10 6 After γ-ray irradiation and LOCA testing (refer to ASTM D3911-2008), there was no fragmentation or peeling.

[0075] Preparation method of fireproof sealing silicone rubber for nuclear power plants

[0076] The fireproof sealing silicone rubber for nuclear power plants of the present invention can be obtained by surface drying and curing the two-component rubber composition described in any embodiment of the present invention.

[0077] In some implementations, the curing temperature is room temperature (25±5℃) and the curing time is 24h; or the temperature is heated to 80-150℃ and the curing time is 10-60min.

[0078] use

[0079] The present invention provides the use of the two-component rubber composition described in any embodiment of the present invention and the fireproof sealing silicone rubber for nuclear power plants described in any embodiment of the present invention in ensuring nuclear safety.

[0080] The present invention will be described below by way of specific embodiments. It should be understood that these embodiments are merely illustrative and are not intended to limit the scope of the invention. The methods, reagents, and materials used in the embodiments and comparative examples are conventional methods, reagents, and materials in the art, unless otherwise stated. The starting material compounds in the embodiments and comparative examples are all commercially available.

[0081] Application examples

[0082] The two-component fire-resistant sealing silicone rubbers of Examples 1-5 and Comparative Examples 1-4 were prepared according to the formulations shown in Table 1, specifically including the following steps: According to the formula shown in Table 1, components A and B are mixed evenly in a vacuum kneader and degassed to obtain component A rubber and component B rubber; then components A and B are injected into parallel double-cylinder packaging at a mass ratio of 1:1 for later use.

[0083] When using, mix components A and B in a 1:1 mass ratio until homogeneous, allow to surface dry at room temperature, and then cure at 25°C for 24 hours (the surface drying time for Examples 1-5 and Comparative Examples 1-3 is 10-50 min; the surface drying time for Comparative Example 4 is ≤5 min), finally obtaining the two-component fireproof sealing silicone rubber of Examples 1-5 and Comparative Examples 1-4.

[0084] The sources of each component in Table 1 are as follows: Methyl vinyl silicone rubber: Hoshine Silicon Industry Co., Ltd., grade 110-2, vinyl content 0.13-0.18 mol%; Methyl vinyl phenyl silicone rubber: Anhui Aiyota Silicone Oil Co., Ltd., brand name IOTA 34, phenyl content 5-8 mol%, vinyl content 0.1-0.35 mol%; Nano CeO2: Shenzhen Jingcai Chemical Co., Ltd., grade JC-Ce01; α-Alumina: Wuhu Jikang New Materials Co., Ltd., grade XD-LA30N; Zinc borate: Jinan Shengfeng Industry & Trade Co., Ltd., industrial grade; Fumed silica: Shanghai Cansen Chemical Co., Ltd., brand name AEROSIL R974; Inhibitor: 1-ethynyl-1-cyclohexanol from Nanjing Qisheng Chemical Co., Ltd.; Hydrogen-containing silicone oil: Ningbo Runhe Advanced Materials Technology Co., Ltd., grade RH-H518, with a hydrogen content of 0.17-0.19%; Hexagonal boron nitride (h-BN): Suzhou Sailon Nano New Materials Industry Co., Ltd., grade BN-1; Pt@LDH: NO3 with a Mg / Al molar ratio of 3:1 was synthesized by co-precipitation method. - LDH was prepared by dispersing it in deionized water, adding chloroplatinic acid solution, and stirring at 60°C for 6 hours for ion exchange and adsorption. NaBH4 solution was then added for in-situ reduction, reducing Pt ions to Pt nanoparticles (5 nm in diameter) which were uniformly anchored on the LDH surface. Surface modification was performed using a mixed silane of vinyltrimethoxysilane and 3-glycidoxypropyltrimethoxysilane (mass ratio of vinyltrimethoxysilane to 3-glycidoxypropyltrimethoxysilane was 1:1) to obtain Pt@LDH, with a final Pt loading of 0.05 wt%.

[0085] Table 1: Formulations of Examples 1-5 and Comparative Examples 1-4 (Unit: parts by mass)

[0086] Test case

[0087] 1. Normal performance

[0088] Shore A hardness: Tested in accordance with GB / T 531.1-2008 "Test method for indentation hardness of vulcanized rubber or thermoplastic rubber - Part 1: Shore hardness tester method (Shore hardness)".

[0089] Tensile strength: The test was conducted in accordance with GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber", using dumbbell-shaped specimens.

[0090] Limiting oxygen index: Tested in accordance with GB / T 2406.2-2009 "Determination of flammability by oxygen index method for plastics - Part 2: Room temperature test".

[0091] The flame retardancy rating of the material is determined according to the UL-94 standard.

[0092] 2. Constructability

[0093] Surface drying time (min, 25°C) was tested according to GB / T 13477.5-2002 "Test methods for building sealing materials - Part 5: Determination of surface drying time". The time from mixing until it no longer adheres to the finger when tested by the finger touch method was recorded.

[0094] 3. After 5×10 6 Following Gyγ irradiation, LOCA simulation tests were conducted according to ASTM D3911-2008, "Standard Test Method for Loss-of-Water Accident (LOCA) Simulation Environment of Coatings for Light Water-Coated Nuclear Power Plants," and the following tests were performed: Tensile strength retention rate: The tensile strength of the irradiated sample was tested according to GB / T 528-2009, and the percentage of its tensile strength before irradiation was calculated. Determine if there is cracking / bubbling.

[0095] 4. High-temperature ceramicization properties

[0096] The sample was calcined in a muffle furnace at 800°C for 10 min. After removal, it was visually observed to see if a continuous and dense ceramic shell was formed. The compressive strength of the ceramic body at 800°C was tested according to GB / T 4740-1999 "Test Method for Compressive Strength of Ceramic Materials" after calcination. The morphology of the ceramic layer was also observed.

[0097] Performance tests were conducted on Examples 1-5 and Comparative Examples 1-4 according to the above test methods or standards, and the test results are shown in Table 2.

[0098] Table 2: Comparison of performance test results between Examples 1-5 and Comparative Examples 1-4

[0099] As shown in Table 2, the product with a total mass fraction of 4 parts of methyl vinyl phenyl silicone rubber (Example 1) exhibited the best overall performance, demonstrating excellent tensile strength, radiation resistance, and ceramic strength. In contrast, Comparative Example 3 (which did not contain methyl vinyl phenyl silicone rubber in component A) showed severe performance degradation after irradiation, and blistering and porous ceramic structure occurred after LOCA. This demonstrates that the introduction of 0.5-3 parts by mass of methyl vinyl phenyl silicone rubber into component A is essential for nuclear-grade applications.

[0100] The experimental data from Examples 1-3 and Comparative Examples 1-2 show that Examples 1 and 3, containing more than 1 part by mass of CeO2, exhibit excellent radiation resistance. Comparative Example 1 (containing 0.1 parts by mass of CeO2) showed a strength retention rate of only 67% after irradiation, demonstrating that the two-component fire-resistant silicone rubber with excessively low CeO2 content does not meet radiation resistance standards. Comparative Example 2 (containing 3 parts by mass of CeO2) showed a decrease in normal tensile strength due to excessive agglomeration of nanofillers, proving that while excessive CeO2 filling is beneficial for irradiation, it impairs basic mechanical properties; therefore, its upper limit should be controlled within 2 parts by mass.

[0101] Example 2, containing 1 part by mass of Pt@LDH, had a surface drying time extended to 50 minutes due to its lower catalyst content, but this was still within an acceptable range. Comparative Example 4, containing 10 parts by mass of Pt@LDH, had too many catalytic sites and reacted too quickly, causing the material to solidify rapidly on the mixing nozzle or application surface, making normal application impossible. This demonstrates that there is a clear upper limit to the amount of Pt@LDH used (Example 5 could still be applied, but the surface drying time was shorter), and more is not necessarily better.

Claims

1. A two-component rubber composition, characterized in that, The two-component rubber composition includes component A and component B, wherein the mass ratio of component A to component B is 1:

1. Based on a total mass of 50 parts by mass of component A, component A comprises 20-35 parts by mass of methyl vinyl silicone rubber, 0.5-3 parts by mass of methyl vinyl phenyl silicone rubber, 1-8 parts by mass of Pt@LDH, 0.5-2 parts by mass of radiation-resistant additive, 4-25 parts by mass of thermal conductivity-enhancing additive, 1-6 parts by mass of flame retardant, 1-4 parts by mass of thixotropic agent, and 0.002-0.05 parts by mass of inhibitor; wherein, in the methyl vinyl phenyl silicone rubber, the molar proportion of phenyl in the side groups of the silicone rubber molecule is 5-25 mol%, and LDH is an inorganic anionic layered double hydroxide compound, wherein the Pt@LDH comprises an inorganic anionic layered double hydroxide compound and platinum nanoparticles supported on the inorganic anionic layered double hydroxide compound; Based on a total mass of 50 parts by mass of component B, component B includes 20-35 parts by mass of methyl vinyl silicone rubber, 0.5-3 parts by mass of methyl vinyl phenyl silicone rubber, 0.5-3 parts by mass of hydrogen-terminated silicone oil, 2-6 parts by mass of neutron absorber, 10-25 parts by mass of structural filler, and 1-4 parts by mass of thixotropic agent. In components A and B, the molar ratio of vinyl groups to active hydrogen in the hydrogen-terminated silicone oil in methyl vinyl silicone rubber and methyl vinyl phenyl silicone rubber is 1:(1.1-1.5).

2. The two-component rubber composition according to claim 1, characterized in that, In the methyl vinyl silicone rubber, the vinyl group accounts for 0.1-0.3 mol of the total organic side groups.

3. The two-component rubber composition according to claim 1, characterized in that, Component A has one or more of the following characteristics: The radiation-resistant additive is selected from one or more of nano-cerium oxide, nano-yttrium oxide, and 2,6-di-tert-butyl-4-methylphenol; The thermal conductivity enhancement agent is selected from one or more of α-alumina, magnesium oxide, aluminum nitride, and silicon carbide; The flame retardant is selected from one or more of zinc borate, aluminum hydroxide, and magnesium hydroxide; The thixotropic agent is selected from one or more of hydrophobic fumed silica, organobentonite, and polyamide wax; The inhibitor is selected from one or both of 1-ethynyl-1-cyclohexanol and 2-methyl-3-butyn-2-ol.

4. The two-component rubber composition according to claim 1, characterized in that, Component B has one or more of the following characteristics: The hydrogen content of the hydrogen-containing silicone oil is 0.1%-0.5%; The neutron absorber is selected from one or more of hexagonal boron nitride, surface-modified B4C, gadolinium oxide, and boric acid; The structural filler is selected from one or more of α-alumina, fumed silica and silica powder; The thixotropic agent is selected from one or more of hydrophobic fumed silica, organobentonite, and polyamide wax.

5. The two-component rubber composition according to claim 4, characterized in that, The D of the α-alumina 50 It is 0.1-1μm.

6. The two-component rubber composition according to claim 1, characterized in that, The Pt@LDH has one or more of the following characteristics: The LDH comprises divalent and trivalent metal ions, wherein the divalent metal ion is Mg. 2+ or Zn 2+ The trivalent metal ion is Al 3+ The molar ratio of the divalent metal ions to the trivalent metal ions is (2.5-3.5):1; The average particle size of the Pt is 2-8 nm; In the Pt@LDH, the mass fraction of Pt is 0.01%-1%; The LDH is NO3. - type; The method for preparing the Pt@LDH includes: synthesizing NO3 with a Mg / Al molar ratio of 2.5-3.5 by co-precipitation. - Type LDH; Pt is loaded onto the LDH surface by thermal reduction or in-situ reduction.

7. A fire-resistant sealing silicone rubber for nuclear power plants, characterized in that, The raw material for the fireproof sealing silicone rubber for nuclear power is the two-component rubber composition as described in any one of claims 1-6.

8. The fireproof sealing silicone rubber for nuclear power plants as described in claim 7, characterized in that, The surface drying time of the two-component rubber composition is 10-60 min.

9. The fireproof sealing silicone rubber for nuclear power plants as described in claim 7, characterized in that, The fire-resistant sealing silicone rubber for nuclear power plants has one or more of the following characteristics: Shore A hardness is 40-70; Tensile strength ≥ 4 MPa; Limiting oxygen index ≥26%; After 5×10 6 The tensile strength retention rate of Gy after γ-irradiation is ≥70%.

10. A method for preparing fire-resistant sealing silicone rubber for nuclear power plants according to any one of claims 7-9, characterized in that, The fireproof sealing silicone rubber for nuclear power plants is obtained by surface drying and curing the two-component rubber composition.

11. The method as described in claim 10, characterized in that, The curing temperature is 25±5℃ and the curing time is 24h; or the curing temperature is 80-150℃ and the curing time is 10-60min.

12. Use of the two-component rubber composition according to any one of claims 1-6 and the fire-resistant sealing silicone rubber for nuclear power plants according to any one of claims 7-9 in ensuring nuclear safety.

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