Ultrahigh-insulation high-performance fluororubber for underground tool of petroleum equipment and preparation method of ultrahigh-insulation high-performance fluororubber

Abstract

The invention relates to the field of sealing accessories, in particular to ultrahigh-insulation high-performance fluororubber for underground tools of petroleum equipment and a preparation method of the ultrahigh-insulation high-performance fluororubber for the underground tools of the petroleum equipment, and the ultrahigh-insulation high-performance fluororubber comprises 100 parts of fluororubber matrix which is vinylidene fluoride-tetrafluoroethylene-perfluoromethyl vinyl ether copolymer; an insulating filler system: 10-15 parts of boron nitride nanosheets; 5-8 parts of surface modified fumed silica; a vulcanization system: 1.5-2 parts of bisphenol AF; 0.5 to 1 part of benzyl triphenyl phosphorus chloride; 0.3 to 0.6 part of benzoyl peroxide; a processing aid: 1-2 parts of hydroxyl silicone oil; 0.5 to 1 part of calcium stearate; an acid-resistant additive: 3-5 parts of nano zirconium oxide, the particle size of which is 20-50nm, and which is in a monoclinic crystal form; the interlayer spacing is larger than or equal to 1.2 nm, and 0.5-1 wt% of silver ions are loaded through an ion exchange method. By constructing a continuous insulation network, the resistivity is greatly improved compared with that of traditional fluororubber, the filler is directionally arranged through the dynamic shearing technology, and the ultrahigh-voltage insulation requirement is met. Meanwhile, an Ag2S passivation layer is generated, H2S permeation is blocked, and the service life is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sealing fittings, in particular to a super-high insulation high-performance fluororubber for downhole tools of oil equipment and a preparation method thereof. BACKGROUND

[0002] The downhole tools of oil are long-term exposed to harsh working conditions of high temperature (> 150℃), super-high pressure (> 100MPa) and high sulfur (H2S concentration > 10%), which puts extreme requirements on the performance of sealing and insulation materials. Although fluororubber has basic corrosion resistance, the traditional material has three fatal defects under extreme conditions: the insulation performance drops sharply, leading to the risk of short circuit of the electric control system; hydrogen sulfide permeation causes rubber swelling and cracking, resulting in sealing failure; thermal aging causes material hardening and embrittlement, and the compression and rebound performance drops sharply. These problems seriously restrict the service life and safety of downhole tools, and the industry urgently needs a new generation of high-performance fluororubber solution.

[0003] Current technologies attempt to improve the performance of fluororubber through filler enhancement and vulcanization system optimization, but all have significant defects:

[0004] 1. High-insulation boron nitride is prone to agglomeration due to dispersion difficulty, and ordinary silicon dioxide has poor compatibility, making it difficult to cooperatively build a stable insulation network; 2. Peroxide vulcanization is fast but poor in heat resistance, and bisphenol vulcanization is good in heat resistance but time-consuming, which cannot balance production efficiency and product reliability; 3. Traditional metal oxides (such as CaO) react with acidic medium to expand in volume, which further aggravates the risk of material cracking; 4. The traditional internal mixing vulcanization process cannot precisely control the orientation of fillers and the crosslinking density, resulting in large fluctuations in product performance and low yield. SUMMARY

[0005] To solve the above problems, the present application provides a super-high insulation high-performance fluororubber for downhole tools of oil equipment and a preparation method thereof. Through the synergistic effect of boron nitride nanosheet pre-dispersion and modified fumed silica, a continuous insulation network is built, the resistivity is greatly improved compared with traditional fluororubber, and the dynamic shear process realizes the directional arrangement of fillers, and the breakdown voltage is improved compared with conventional process, meeting the demand for super-high pressure insulation. At the same time, Ag2S passivation layer is generated to block H2S permeation, prolonging the service life. The bisphenol AF / BPP / BPO synergistic vulcanization system builds a double crosslinking network, and the heat resistance is improved compared with single vulcanization system.

[0006] To achieve the above purpose, the technical scheme adopted by the present application is as follows: a super-high insulation high-performance fluororubber for downhole tools of oil equipment, comprising the following components by weight:

[0007] Fluororubber matrix: 100 parts, which is a vinylidene fluoride-tetrafluoroethylene-perfluoromethyl vinyl ether copolymer;

[0008] Insulating filler system: boron nitride nanosheet: 10-15 parts; surface modified fumed silica: 5-8 parts;

[0009] Vulcanizing system: bisphenol AF: 1.5-2 parts; benzyl triphenyl phosphonium chloride: 0.5-1 part; benzoyl peroxide: 0.3-0.6 part;

[0010] Processing aid: hydroxyl silicone oil: 1-2 parts; calcium stearate: 0.5-1 part;

[0011] Acid-resistant additive: nano-zirconium oxide: 3-5 parts, particle size 20-50 nm, and monoclinic crystal; zirconium phosphate: 2-4 parts, interlayer spacing ≥1.2 nm, and loaded with 0.5 to 1 wt% of silver ions by ion exchange method.

[0012] Further, the fluorine content of the fluororubber matrix is 70% to 72%, and the Mooney viscosity ML1+10 at 121℃ is 45 to 55.

[0013] Further, the particle size of the boron nitride nanosheet is 50 nm to 100 nm, the specific surface area is greater than or equal to 200 square meters per gram, and it is pre-dispersed by hydroxyl silicone oil, wherein the weight ratio of hydroxyl silicone oil to boron nitride nanosheet is 1 to 5 to 1 to 8, the pre-dispersing temperature is 75℃ to 85℃, the shearing rotation speed is 2500 rpm to 3500 rpm, and the pre-dispersing time is 25 minutes to 35 minutes.

[0014] Further, the hydroxyl content of the surface modified fumed silica is less than or equal to 0.5%, and it is modified by silane coupling agent KH550, and the silane coupling agent is used in an amount of 2% to 3% of the weight of the fumed silica.

[0015] Further, the mass ratio of the boron nitride nanosheet to the surface modified fumed silica is 1.8 to 1 to 2.5 to 1, and the total amount of both is 18% to 22% of the weight of the fluororubber matrix.

[0016] The beneficial effects of the present application are:

[0017] 1. By the synergistic effect of boron nitride nanosheet pre-dispersion and modified fumed silica, a continuous insulating network is constructed, the resistivity is greatly improved compared with traditional fluororubber, and the risk of short circuit of downhole electric control system is completely solved. Moreover, the dynamic shearing process realizes the directional arrangement of fillers, the breakdown voltage is improved compared with conventional process, and the ultra-high pressure insulation demand is met.

[0018] 2. The silver-loaded zirconium phosphate generates an Ag2S passivation layer, blocks the penetration of H2S, reduces the corrosion rate compared with traditional materials, and prolongs the service life. The nano-zirconium oxide efficiently adsorbs H + , and the acid corrosion inhibition ability is improved compared with ordinary additives, which is suitable for high-acid oil and gas field environment.

[0019] 3. The bisphenol AF / BPP / BPO synergistic vulcanization system constructs a double cross-linked network, and the heat resistance is improved compared with the single vulcanization system.

[0020] 4. Dynamic vulcanization precise temperature control and nitrogen protection process inhibit thermal oxidation degradation, and the deformation rate is lower than that of traditional processes, ensuring long-term resilience of seals. DETAILED DESCRIPTION

[0021] Example 1:

[0022] An ultra-high insulation and high-performance fluororubber for downhole tools of petroleum equipment, comprising by weight

[0023] Rubber matrix: 100 parts by weight (vinylidene fluoride-tetrafluoroethylene-perfluoromethyl vinyl ether copolymer, fluorine content 71 wt%, Mooney viscosity ML (1+10) @ 121°C 50±2);

[0024] Insulation filler system: Boron nitride nanosheets: 12 parts by weight (particle size 80±5nm, specific surface area 220±10m 2 / g, pre-dispersed with hydroxyl silicone oil); surface-modified fumed silica: 6 parts by weight (hydroxyl content 0.4±0.1wt%, modified with silane coupling agent KH550, silane loading 2.5±0.2wt%);

[0025] Curing system: Bisphenol AF: 1.8 parts by weight; Benzyltriphenylphosphonium chloride: 0.6 parts by weight; Benzoyl peroxide: 0.5 parts by weight;

[0026] Processing aids: hydroxy silicone oil: 1.5 parts by weight (viscosity 600±50 cP, 25°C); calcium stearate: 0.8 parts by weight;

[0027] Acid-resistant additive: Nano zirconium oxide: 4 parts by weight (particle size 30±5nm, monoclinic crystal, unit cell parameters ); Zirconium phosphate: 3 parts by weight (interlayer spacing 1.3 ± 0.05 nm, Ag + Loading amount 0.8±0.05wt%).

[0028] Preparation method

[0029] Step 1: Pre-dispersion of Boron Nitride Nanosheets

[0030] Equipment: High-speed shear disperser (model FLUKO FA25, rotor diameter 50 mm, stator-rotor gap 0.5 mm);

[0031] Process parameters: boron nitride nanosheets and hydroxyl silicone oil were fed at a weight ratio of 1:6; dispersion temperature: 80±2℃ (controlled by circulating water bath); shear rotation speed: 3000±100rpm; dispersion time: 30±1min; end point control: slurry viscosity 650±50cP (Brookfield DV2T viscometer, rotor LV3, 25℃);

[0032] The effect of this process step is that the hydroxyl silicone oil breaks the interlayer hydrogen bonds of boron nitride, and the size of the boron nitride agglomerates in the pre-dispersed slurry is ≤100nm (detected by SEM).

[0033] Step 2: Banbury mixing

[0034] Equipment: Banbury mixer (model X(S)M-500, volume 5L, rotor rotation speed 0-100rpm adjustable);

[0035] Feeding sequence: fluorine rubber matrix (100 parts by weight) was fed into the Banbury chamber, and the initial temperature was set to 50±2℃; the pre-dispersed slurry of step 1 and surface modified fumed silica were added in turn;

[0036] Mixing parameters: rotor rotation speed: 40rpm; mixing time: 5±0.5min; end point temperature: 120±2℃ (real-time monitored by thermocouple);

[0037] The effect of this process step is that the fumed silica and the pre-dispersed boron nitride form an interpenetrating network, and the D90 of the filler dispersion uniformity after mixing is ≤5μm.

[0038] Step 3: Dynamic vulcanization

[0039] Equipment: co-rotating twin-screw extruder (model SHJ-36, length-diameter ratio 48:1, screw diameter 36mm);

[0040] Process parameters: the mixing rubber of step 2 was cooled to 80±2℃ (controlled by cooling water circulation system); acid-resistant additives (nano-zirconium oxide, zirconium phosphate), vulcanization system (bisphenol AF, BPP, BPO) and calcium stearate were added in turn, and mixed for 3±0.5min;

[0041] Dynamic vulcanization extrusion parameters: temperature zoning: zone one 130±2℃, zone two 135±2℃, zone three 140±2℃; screw rotation speed: 220±5rpm; shear rate: 550±20s -1 ; residence time: 2.5±0.2min; end point control: Mooney viscosity of extruded rubber ML(1+4)@125℃ is 48±2MU;

[0042] The effect of this process step is that the high shear rate (550s -1) to align the fillers (XRD shows (002) crystal orientation ≥ 0.95), and the dynamic vulcanization crosslinking density reaches 1.2×10 -4 mol / cm 3 (Swelling test).

[0043] Step 4: Second stage vulcanization

[0044] Equipment: Program-controlled curing oven (model XLB-D, temperature accuracy ±1°C);

[0045] Curing procedure: First stage: heating at 2±0.2°C / min to 180±2°C, holding at this temperature for 2±0.1 hours; Second stage: heating at the same rate to 230±2°C, holding at this temperature for 8±0.1 hours; Environmental control: nitrogen protection throughout the process (flow rate 10±0.5L / min, purity ≥99.999%);

[0046] The purpose of this process step is to eliminate internal stress by segmented vulcanization and finally increase the cross-linking density to 1.5×10 -4 mol / cm 3 , Tg (glass transition temperature) reaches -15±1℃ (DSC test)

[0047] Specific embodiment 2 (filler ratio and vulcanization system adjustment)

[0048] An ultra-high insulation and high-performance fluororubber for downhole tools of petroleum equipment, comprising by weight

[0049] Fluororubber matrix: 100 parts by weight (vinylidene fluoride-tetrafluoroethylene-perfluoromethyl vinyl ether copolymer, fluorine content 70%, Mooney viscosity ML1+10@121°C: 45);

[0050] Insulation filler system: Boron nitride nanosheets: 15 parts by weight (particle size 100 nm, specific surface area 200 m 2 / g, pre-dispersed with hydroxyl silicone oil); surface-modified fumed silica: 5 parts by weight (hydroxyl content 0.5%, silane coupling agent KH550 dosage 3%);

[0051] Curing system: Bisphenol AF: 2.0 parts by weight; Benzyltriphenylphosphonium chloride: 1.0 parts by weight;

[0052] Benzoyl peroxide: 0.3 parts by weight;

[0053] Processing aids: hydroxy silicone oil: 2.0 parts by weight (viscosity 800 cP); calcium stearate: 1.0 parts by weight; acid-resistant additives: nano zirconium oxide: 3 parts by weight (particle size 50 nm, monoclinic); zirconium phosphate: 2 parts by weight (interlayer spacing 1.2 nm, Ag + Loading 0.5 wt%).

[0054] Preparation process of Example 2

[0055] Pre-dispersion: Boron nitride nanosheets and hydroxy silicone oil are mixed in a weight ratio of 1:5 and shear dispersed at 85°C and 3500 rpm for 25 minutes. The slurry viscosity is 800 cP @ 25°C. Technical effect: The hydrogen bonds between boron nitride layers are quickly broken at high temperature and high speed (SEM shows that the agglomerate size is ≤ 80 nm).

[0056] Internal mixing: fluororubber matrix + slurry + fumed silica, mixing to 120°C (rotor speed 35 rpm, time 6 minutes); total filler amount: 20 parts by weight.

[0057] Dynamic vulcanization: Cool down to 80°C, add acid-resistant additives, vulcanization system and calcium stearate, and mix for 4 minutes; twin-screw extruder parameters: aspect ratio 48:1, temperature 140°C, screw speed 250rpm, shear rate 600s -1 ; End point control: Mooney viscosity ML (1+4) @ 125 ℃ is 55MU.

[0058] Second stage vulcanization: 180°C×2h+230°C×8h, nitrogen flow rate 12 L / min (slightly higher than 10 L / min in Example 1).

[0059] The technical effects of Example 2 are: high filler loading (20%): boron nitride accounts for 75% (15 / 20), which dominates the formation of a dense insulating network (resistivity 4.2×1015Ω·cm); vulcanization ratio 4:1:0.3: excessive bisphenol AF enhances thermal stability (200℃ tensile retention 91%); high shear rate (600s -1 )

[0060] : The (002) crystal orientation of boron nitride reaches 0.97 (XRD) and the dielectric strength is 29.1kV / mm.

[0061] Example 3 (Acid-resistant additive enhancement and process optimization)

[0062] An ultra-high insulation and high-performance fluororubber for downhole tools of petroleum equipment, comprising, by weight:

[0063] Fluororubber matrix: 100 parts by weight (vinylidene fluoride-tetrafluoroethylene-perfluoromethyl vinyl ether copolymer, fluorine content 72%, Mooney viscosity ML (1+10) @ 121°C 55);

[0064] Insulation filler system: Boron nitride nanosheets: 10 parts by weight (particle size 50 nm, specific surface area 250 m 2 / g); surface modified fumed silica: 8 parts by weight (hydroxyl content 0.3%, silane coupling agent KH550 amount 2%);

[0065] Vulcanization system:

[0066] Bisphenol AF: 1.5 parts by weight;

[0067] Benzyltriphenylphosphonium chloride: 0.5 parts by weight;

[0068] Benzoyl peroxide: 0.6 parts by weight;

[0069] Processing aids:

[0070] Hydroxyl silicone oil: 1.0 part by weight (viscosity 500 cP, 25°C);

[0071] Calcium stearate: 0.5 parts by weight;

[0072] Acid-resistant additives:

[0073] Nano-zirconia: 5 parts by weight (particle size 50 nm, monoclinic crystal, unit cell parameters );

[0074] Zirconium phosphate: 4 parts by weight (interlayer spacing 1.4 nm, Ag + Loading amount 1.0 wt%).

[0075] Example 3 Preparation process

[0076] Step 1: Pre-dispersion of Boron Nitride Nanosheets

[0077] Equipment: High-speed shear disperser (FLUKO FA25, rotor diameter 50 mm, stator-rotor gap 0.5 mm)

[0078] Feed ratio: Boron nitride nanosheets: Hydroxyl silicone oil = 1:8 (weight ratio)

[0079] Process parameters:

[0080] Dispersion temperature: 80±2℃ (temperature controlled by circulating water bath)

[0081] Shear speed: 3000±100rpm

[0082] Dispersion time: 30±1 minutes

[0083] End point control: slurry viscosity 650±50 cP (Brookfield DV2T viscometer, rotor LV3, 25°C)

[0084] Function: Hydroxyl silicone oil destroys the hydrogen bonds between boron nitride layers. The size of the agglomerates after pre-dispersion is ≤100nm (SEM detection).

[0085] Step 2: Mixing

[0086] Equipment: Internal mixer (model X(S)M-500, volume 5L, rotor speed adjustable 0-100rpm)

[0087] Feeding order:

[0088] Fluororubber matrix (100 parts by weight) was placed in a mixing chamber, and the initial temperature was set at 50±2°C;

[0089] Add the boron nitride pre-dispersed slurry from step 1;

[0090] Surface-modified fumed silica (8 parts by weight, 0.3% hydroxyl content, KH550 modified) was added.

[0091] Mixing parameters:

[0092] Rotor speed: 40rpm

[0093] Mixing time: 5±0.5 minutes

[0094] End point temperature: 120±2℃ (real-time monitoring by thermocouple)

[0095] Function: Fumed silica and pre-dispersed boron nitride form an interpenetrating network. After mixing, the filler dispersion uniformity D90 ≤ 5μm.

[0096] Step 3: Dynamic Vulcanization

[0097] Equipment: Co-rotating twin-screw extruder (model SHJ-36, aspect ratio 48:1, screw diameter 36 mm) Process parameters: Cool the rubber compound from step 2 to 85 ± 2 °C (temperature controlled by cooling water circulation system);

[0098] Acid-resistant additives (5 parts of nano-zirconium oxide and 4 parts of zirconium phosphate), a vulcanization system (1.5 parts of bisphenol AF, 0.5 parts of benzyltriphenylphosphine chloride, 0.6 parts of benzoyl peroxide) and 0.5 parts of calcium stearate were added in sequence; after mixing for 3±0.5 minutes, dynamic vulcanization was performed through a twin-screw extruder.

[0099] Dynamic vulcanization extrusion parameters:

[0100] Temperature zones: Zone 1 130±2℃, Zone 2 135±2℃, Zone 3 140±2℃;

[0101] Screw speed: 200±5rpm

[0102] Shear rate: 500s -1

[0103] Residence time: 2.5±0.2 minutes

[0104] End point control: Mooney viscosity of extruded rubber ML (1+4) @ 125℃ is 45±2MU

[0105] effect:

[0106] High shear rate (500s -1 ) to align the fillers (XRD shows (002) crystal orientation ≥ 0.95), and the dynamic vulcanization crosslinking density reaches 1.2×10 -4 mol / cm 3 (Swelling test).

[0107] Step 4: Second stage vulcanization

[0108] Equipment: Program-controlled curing oven (model XLB-D, temperature accuracy ±1°C)

[0109] Vulcanization procedure:

[0110] Stage 1: Raise the temperature to 180±2℃ at 2±0.2℃ / min and keep warm for 2±0.1 hours;

[0111] Stage 2: Continue heating at the same rate to 230±2℃ and keep warm for 8±0.1 hours;

[0112] Environmental control: Nitrogen protection throughout the process (flow rate 10±0.5L / min, purity ≥99.999%).

[0113] Function: Segmented vulcanization eliminates internal stress and ultimately increases the cross-linking density to 1.5×10 -4 mol / cm 3 , Tg (glass transition temperature) reaches -15±1℃ (DSC test).

[0114] The technical effects of Example 3 are:

[0115] Acid-resistant additive reinforcement: 5 parts of nano-zirconia, specific surface area 120m 2 / g, HCl corrosion rate is only 0.5%; Ag zirconium phosphate + Loading 1.0wt%, H2S corrosion rate 2.5%. Reduces thermal degradation of fluororubber and maintains Mooney viscosity at 45MU (better processability).

[0116] For accurate comparison, two comparative examples were set up, where only key variables were changed, while the remaining components and processes remained consistent:

[0117] Comparative Example 1 (unmodified filler) includes, by mass:

[0118] Boron nitride nanosheets: 12 parts (not pre-dispersed, agglomerated particle size > 500 nm);

[0119] Fumed silica: 6 parts (unmodified, hydroxyl content 1.2%);

[0120] Acid-resistant additives: None;

[0121] Curing system: 2.9 parts of dicumyl peroxide (DCP)

[0122] Process: Internal mixer vulcanization (no dynamic shear)

[0123] Comparative Example 2 (without acid-resistant additives) includes, by mass: Formulation: the same as Example 1, except that nano zirconium oxide and zirconium phosphate are deleted; Process: dynamic vulcanization parameters are consistent with those of Example 1.

[0124] Test items and standards

[0125]

[0126] 1. Insulation performance

[0127] Test items Example 1 Comparative Example 1 Comparative Example 2 Volume resistivity (Ω·cm) <![CDATA[3.8×10 15 ]]> 5.6 x 10 13 ]]> <![CDATA[2.1×10 15 ]]> Dielectric strength (kV / mm) 27.5 14.8 24.3

[0128] Performance Analysis:

[0129] Example 1 vs. Comparative Example 1: Pre-dispersed boron nitride and modified SiO2 (contact angle 15°) form a continuous insulating network, increasing the resistivity by 68 times; Example 1 vs. Comparative Example 2: The acid-resistant additive (nano-zirconia) inhibits ion migration, increasing the resistivity by another 81% (from 0.1×1015 → 3.8×1015 Ω·cm).

[0130] 2. Corrosion resistance

[0131] Test conditions Example 1 (Volume Change Rate) Comparative Example 1 Comparative Example 2 <![CDATA[10%H2S水溶液(70℃×168h)]]> 2.9％ 12.3％ 8.7％ 10% HCl solution (70°C × 168h) 0.7％ 3.1％ 5.2％

[0132] Performance analysis: Zirconium phosphate (Ag + ): Reacts with H2S to form an Ag2S passivation layer (EDS shows that the surface S content is ≤0.1at%), and the corrosion rate is reduced by 76% (12.3%→2.9%); Nano-zirconia: Monoclinic ZrO2 adsorbs H + (XPS shows that the surface Zr-OH bond ratio is >60%), and the HCl corrosion rate is reduced by 86% (5.2%→0.7%).

[0133] 3. High temperature stability

[0134] Test items Example 1 Comparative Example 1 Comparative Example 2 200℃×72h tensile retention 89％ 50％ 75％ Compression set (200℃) 15％ 40％ 22％

[0135] Performance analysis: Synergistic vulcanization system: Bisphenol AF / BPP / BPO builds an ion-free radical double cross-linking network (cross-linking density 1.5×10 -4 mol / cm 3 ), tensile retention increased by 78% (50%→89%); dynamic shear orientation: filler directional arrangement (XRD orientation degree 0.95) reduced stress concentration and compression deformation decreased by 62.5% (40%→15%).

[0136] 4. Processability

[0137] Test items Example 1 Comparative Example 1 Comparative Example 2 Mooney viscosity (ML1+4@125℃) 48MU 82MU 50MU Extrusion surface roughness Ra (μm) 0.8 2.4 1.2

[0138] Performance analysis: pre-dispersion process: hydroxyl silicone oil reduces the internal friction of the filler (viscosity 650 cP), the Mooney viscosity is only 58% of that of Comparative Example 1; dynamic shear: high shear rate (550 s -1 ) improves flowability, and the Ra value is reduced by 67% (2.4→0.8 μm).

[0139] Conclusion

[0140] Through the quantitative data verification of the precision variable control of the comparative example, the scheme (Example 1) of the present application realizes a technical breakthrough in the following aspects: the volume resistivity is 3.8×1015Ω·cm, reaching the international level of insulation materials for downhole tools (API 6A requires ≥1×1014Ω·cm); the H2S corrosion rate is 2.9%, which is better than the industry standard (NACE TM0188 requires ≤5%); the compression permanent deformation at 200℃ is 15%, which is reduced by 62.5% compared with the traditional scheme (40%); the dynamic shear process parameters are clear (shear rate 550±20 s -1 ), and the Mooney viscosity fluctuation is ≤±2 MU, meeting the needs of industrial production.

[0141] The above embodiments only describe the preferred embodiments of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by ordinary engineering technicians in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. An ultra-high insulation and high-performance fluororubber for downhole tools of petroleum equipment, comprising the following components in parts by weight: Fluororubber matrix: 100 parts, which is vinylidene fluoride-tetrafluoroethylene-perfluoromethyl vinyl ether copolymer; Insulating filler system: Boron nitride nanosheets: 10-15 parts; Surface modified fumed silica: 5-8 parts; Curing system: Bisphenol AF: 1.5-2 parts; Benzyl triphenylphosphonium chloride: 0.5-1 part; Benzoyl peroxide: 0.3-0.6 parts; Processing aid: Hydroxy silicone oil: 1-2 parts; Calcium stearate: 0.5-1 part; Acid-resistant additives: nano zirconium oxide: 3-5 parts, particle size 20-50nm, and monoclinic crystal; zirconium phosphate: 2-4 parts, interlayer spacing ≥1.2nm, and loaded with 0.5 to 1wt% silver ions through ion exchange method.

2. The ultra-high insulation and high performance fluororubber for downhole tools of petroleum equipment according to claim 1, characterized in that: The fluorine content of the fluororubber matrix is ​​70% to 72%, and the Mooney viscosity ML (1+10) is 45 to 55 at 121°C.

3. The ultra-high insulation and high performance fluororubber for downhole tools of petroleum equipment according to claim 1, characterized in that: The boron nitride nanosheets have a particle size of 50 nanometers to 100 nanometers, a specific surface area greater than or equal to 200 square meters per gram, and are pre-dispersed with hydroxyl silicone oil, wherein the weight ratio of hydroxyl silicone oil to boron nitride nanosheets is 1 to 5 to 1 to 8, the pre-dispersion temperature is 75°C to 85°C, the shear speed is 2500 rpm to 3500 rpm, and the pre-dispersion time is 25 minutes to 35 minutes.

4. The ultra-high insulation and high performance fluororubber for downhole tools of petroleum equipment according to claim 1, characterized in that: The surface-modified fumed silica has a hydroxyl content of less than or equal to 0.5%, and is modified by using a silane coupling agent KH550, wherein the amount of the silane coupling agent used is 2% to 3% of the weight of the fumed silica.

5. The ultra-high insulation and high performance fluororubber for downhole tools of petroleum equipment according to claim 1, characterized in that: The mass ratio of the boron nitride nanosheets to the surface-modified fumed silica is 1.8 to 1 to 2.5 to 1, and the total amount of the two accounts for 18% to 22% of the weight of the fluororubber matrix.

6. The ultra-high insulation and high performance fluororubber for downhole tools of petroleum equipment according to claim 1, characterized in that: The weight ratio of bisphenol AF, benzyl triphenyl phosphonium chloride and benzoyl peroxide in the vulcanization system is 3:1:0.5 to 4:1:0.

8.

7. A method for preparing the ultra-high insulation and high-performance fluororubber for downhole tools of petroleum equipment according to any one of claims 1 to 6, comprising the following steps: a. Pre-dispersing the boron nitride nanosheets and hydroxy silicone oil in proportion to form a homogeneous slurry; b. Add the fluororubber matrix to the internal mixer, sequentially add the slurry and surface-modified fumed silica, and mix until the temperature reaches 120°C; c. Add vulcanization system, processing aids and acid-resistant additives, mix and then pass through a twin-screw extruder for dynamic vulcanization; d. Perform two-stage vulcanization, including the first stage at 180°C for 2 hours and the second stage at 230°C for 8 hours, the entire process being carried out under nitrogen protection.

8. The method for preparing ultra-high insulation and high performance fluororubber for downhole tools of petroleum equipment according to claim 7, characterized in that: The specific steps of step c are: cooling to 80° C., adding an acid-resistant additive, a vulcanization system and calcium stearate, mixing for 3 minutes, and then dynamically vulcanizing through a twin-screw extruder, wherein the aspect ratio of the twin-screw extruder is 48 to 1, the temperature is 130° C. to 140° C., the screw speed is 200 to 250 rpm, and the shear rate is 500 seconds -1 to 600 seconds -1.

Images