A rodent and termite resistant cable jacket material composition comprising a fluoroelastomer

Abstract

The present application relates to the technical field of high polymer compound composition, and discloses a kind of fluorine-containing rubber's rat bite prevention termite cable sheath material composition, comprising vinylidene fluoride base fluorine-containing rubber matrix and modified mesoporous calcium fluoride powder, by filling repellent component to mesoporous calcium fluoride carrier nanopore, and in orifice enrichment accelerator and on surface grafting functional group preparation, accelerator induces local crosslinking of matrix in carrier orifice when composition vulcanization, form dense crosslinking layer, the present application utilizes dense crosslinking layer to physically lock repellent component at room temperature, and with temperature increase adjustment network gap realizes controlled permeation, solve fluorine-containing rubber matrix small molecule additive blooming problem, maintain long-term biological repellent efficiency, and synergistically enhance the fatigue resistance of sheath material.

Description

Technical Field

[0001] This invention relates to a fluororubber-containing cable sheath material composition that is rodent-proof and termite-proof, belonging to the technical field of polymer compound compositions. Background Technology

[0002] Currently, fluororubber compositions have excellent weather resistance, media resistance, and mechanical strength, and are widely used in the field of cable sheathing in underground power tunnels. To address the threats to power transmission safety posed by rodent gnawing and termite infestation, capsaicin, bittering agents, or organophosphorus repellents are usually added to the fluororubber matrix. The protective effectiveness is maintained by utilizing the physical migration of the repellents to the material surface.

[0003] Existing research primarily focuses on improving dispersibility and reinforcement through optimizing filler geometry and surface modification. However, even after filler morphology optimization, current technologies still fall short in addressing the dynamic response and controlled release of small molecules under complex environments. For instance, Chinese invention patent CN109370117B discloses a high flame-retardant and aging-resistant fluororubber cable sheath material. This material introduces branched polyphenolic hydroxyl acrylate rubber combined with ball-milled modified zinc sulfate, constructing a stable physical filling network through multi-component co-vulcanization. While the chemical coordination between components enhances static strength and flame-retardant properties, the interface structure remains a static, closed system, lacking the ability to dynamically regulate additives as environmental temperature changes. Because the molecular chains of fluororubber have extremely small inter-chain gaps, the repellent, as a small molecule additive, has limited physical space within the matrix. In the thermal cycling environment of underground tunnels where the temperature fluctuates between 30°C and 90°C, volume repulsion occurs between the fluororubber matrix and the small molecules, inducing an extrusion effect. This leads to the precipitation of the repellent and blooming, causing a rapid decline in protective effectiveness. Furthermore, the accumulation of small molecules at the interface can cause stress concentration, leading to cracking of the sheath under dynamic bending conditions. Increasing the proportion of carrier or raising the initial concentration to offset losses often disrupts the continuity of the fluororubber crosslinking network, resulting in a decrease in material toughness and dynamic fatigue resistance.

[0004] Therefore, how to construct a static composition system with interface adaptive locking characteristics to achieve controlled penetration of the repellent in the fluororubber matrix and simultaneously enhance the interfacial stress buffering capacity has become the technical problem to be solved by this invention. Summary of the Invention

[0005] To address the problems mentioned in the background art, the technical solution of the present invention is as follows: a fluororubber-containing rodent-proof and termite-proof cable sheath material composition, the composition comprising:

[0006] Vinylidene fluoride fluorinated rubber matrix and modified mesoporous calcium fluoride powder;

[0007] The modified mesoporous calcium fluoride powder includes a mesoporous calcium fluoride carrier, a repellent component filling the nanopores of the mesoporous calcium fluoride carrier, and a dense cross-linked layer disposed at the pore opening of the nanopores.

[0008] Modified mesoporous calcium fluoride powder is prepared through the following steps:

[0009] Step S1: Under a vacuum of 0.01 MPa, the mesoporous calcium fluoride support is immersed in a eutectic composed of synthetic capsaicin and denatured bittering agent, allowing the eutectic to enter a cavity with an average pore size of 10 nm to 30 nm and a specific surface area of... to Within the nanopores, a saturated carrier is formed;

[0010] Step S2: Add 0.5 wt% of bisphenol AF promoter to the saturated carrier to form a local enrichment layer at the pore edge of the nanopores.

[0011] Step S3 involves surface modification of the product obtained in step S2 using a silane coupling agent by grafting unsaturated double bond functional groups onto the outer surface of the mesoporous calcium fluoride support to obtain modified mesoporous calcium fluoride powder. During the vulcanization of the composition, the bisphenol AF accelerator enriched at the pore edges induces a local crosslinking reaction in the vinylidene fluoride fluorinated rubber matrix at the pore openings, forming a dense crosslinked layer. At 25°C, the gap between the crosslinking networks in the dense crosslinked layer is smaller than the molecular dynamic diameter of the repelling component, thus physically locking the repelling component. At temperatures ranging from 30°C to 90°C, the expansion of the free volume of the crosslinking network in the dense crosslinked layer increases the gap between the crosslinking networks, allowing the repelling component to penetrate into the surface of the vinylidene fluoride fluorinated rubber matrix in a controlled manner.

[0012] Preferably, by weight, the composition comprises: 100 phr of vinylidene fluoride fluorinated rubber matrix, 5 to 15 phr of modified mesoporous calcium fluoride powder, 3 to 8 phr of acid scavenger, 1 to 3 phr of vulcanizing agent, and 0.5 to 1.5 phr of processing aid; wherein, in step S1, the loading of the eutectic in the nanopores accounts for more than 85% of the total pore volume of the mesoporous calcium fluoride carrier; and the mass ratio of synthetic capsaicin to modified bittering in the eutectic is 3:1.

[0013] Preferably, the vinylidene fluorinated rubber matrix is ​​a copolymer of vinylidene fluoride and perfluoropropylene, or a terpolymer of vinylidene fluoride, perfluoropropylene and tetrafluoroethylene; the mass content of vinylidene fluoride units in the vinylidene fluorinated rubber matrix is ​​60wt% to 80wt%, and the Mooney scorch time MS+1 at 121°C is not less than 25min.

[0014] Preferably, in step S1, the eutectic is prepared by mixing synthetic capsaicin with denatured bittering and heat-treating at 85°C for 2 hours; the average particle size of the mesoporous calcium fluoride carrier is 0.5 μm to 2.0 μm.

[0015] Preferably, the silane coupling agent is vinyltrimethoxysilane or vinyltriethoxysilane; the grafting density of unsaturated double bond functional groups on the surface of the mesoporous calcium fluoride support is [insert density here]. to .

[0016] Preferably, in step S2, the thickness of the dense cross-linked layer is 1 nm to 3 nm.

[0017] Preferably, the acid absorbent is composed of magnesium oxide and calcium hydroxide in a mass ratio of 1:1; the vulcanizing agent is bisphenol AF; and the processing aids include carnauba wax or calcium stearate.

[0018] Preferably, the dense cross-linked layer is chemically bonded to the fluorinated vinylidene fluoride rubber matrix through interfacial chemical bonding of unsaturated double bond functional groups, so that the modified mesoporous calcium fluoride powder is embedded in the rubber network as an active cross-linking node. This is used to improve the surface hardness of the material while transferring and dispersing the micro-stress during dynamic bending through interfacial chemical bonding.

[0019] Preferably, the pore size parameters of the mesoporous calcium fluoride support satisfy the following mathematical relationship: ,in, The average pore size of the nanopores is expressed in units of 100 nm. ; The unit pore volume of the mesoporous calcium fluoride carrier is expressed in units of 1000 ppm. ; The specific surface area of ​​the mesoporous calcium fluoride carrier is given in units of... Mathematical relationships are used to establish the geometric space of nanopores to limit the maximum loading of the eutectic.

[0020] Preferably, the composition further includes 1 wt% to 5 wt% of reinforcing filler, which is fluorinated carbon black or precipitated silica, in proportion to the mass of the vinylidene fluorinated rubber matrix, and is used to adjust the Mooney viscosity and hardness balance of the composition.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. In rodent-proof and termite-proof cable sheathing materials, by enriching vulcanization accelerators at the edges of mineral carrier pores, local ultrafast cross-linking reactions are induced at the carrier interface during a vulcanization stage, forming a nanoscale dense cross-linked layer and constructing a molecular gate system with thermodynamic response characteristics. At room temperature, the biological repellent components inside the mesopores are locked, and the gaps in the cross-linked network are adjusted with thermal shock during service, realizing the transformation of the repellent from free diffusion to controlled micro-penetration. This avoids the repellent from blooming and loss due to extrusion effect at high temperatures, maintains the pain threshold concentration on the material surface, and solves the problem of small molecule additive precipitation caused by the extremely small gaps between fluororubber molecular chains.

[0023] 2. A reactive mineral carrier with unsaturated double bonds and silane functional groups grafted onto its surface is used. During vulcanization, the carrier particles are transformed into macromolecular cross-linking nodes of fluororubber molecular chains. Through chemical bonding, the physical interface between the filler and the matrix is ​​eliminated. This structural integration method transforms the filler, which is prone to stress concentration, into an interface reinforcement center. While improving the sheath hardness to prevent biological biting, the chemical cross-linking network disperses the micro-stress generated by dynamic bending, effectively inhibiting environmental stress cracking and improving the fatigue life of the cable sheath in the alternating stress environment of underground tunnels.

[0024] 3. By leveraging the intrinsic affinity between the mesoporous calcium fluoride carrier and the fluororubber matrix, and in conjunction with the vacuum saturation filling process, the repellent components are deeply positioned within the carrier, eliminating the risk of structural loosening caused by the random distribution of small molecule additives. By statically anchoring the repellent components in the chemically locked network nodes, the repellent is prevented from leaving microscopic voids inside the material after loss, maintaining the overall compactness and media barrier properties of the fluororubber sheath, blocking the path of groundwater vapor to penetrate into the cable, and ensuring the service safety of the entire cable system. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the preparation process of the composition of the present invention and the molecular gating mechanism based on the dense cross-linked layer;

[0026] Figure 2 This is a time series diagram showing the physical lock-in and controlled permeation dynamic response of the repellent component under thermal cycling conditions according to the present invention. Detailed Implementation

[0027] The technical solution of the present invention will be described in detail below. The following embodiments are intended to explain the present invention and are not intended to limit the scope of protection of the present invention.

[0028] This invention provides a fluororubber-containing rodent- and termite-resistant cable sheath material composition, comprising a vinylidene fluoride (VDF) fluorinated rubber matrix and modified mesoporous calcium fluoride powder. VDF fluorinated rubber is selected as the matrix to address the complex cable operating environment of underground power tunnels, utilizing its weather resistance, dielectric resistance, and mechanical strength. The VDF fluorinated rubber matrix is ​​selected as a copolymer of vinylidene fluoride and perfluoropropylene, or a terpolymer of vinylidene fluoride, perfluoropropylene, and tetrafluoroethylene. The VDF unit content in the VDF fluorinated rubber matrix is ​​60wt% to 80wt%, and the Mooney scorch time (MS+1) at 121°C is not less than 25 min. To address the problem of blooming and loss of small repellent molecules in the fluororubber matrix due to limited physical space, an average pore size of 10nm to 30nm and a specific surface area of ​​150 nm are introduced. Up to 250 Mesoporous calcium fluoride carriers were used; under a vacuum of 0.01 MPa, the mesoporous calcium fluoride carriers were immersed in a eutectic composed of synthetic capsaicin and modified bittering agent; the eutectic agent was used to saturate and fill the nanopores of the nanopores through capillary pressure; the eutectic agent was further processed by mixing synthetic capsaicin and modified bittering agent at a mass ratio of 3:1 and heat-treating at 85°C for 2 days. The eutectic was prepared; the loading of the eutectic within the nanopores accounted for 85% of the total pore volume of the mesoporous calcium fluoride carrier. The average particle size of the mesoporous calcium fluoride support is 0.5 μm to 2.0 μm; the pore size parameters of the mesoporous calcium fluoride support satisfy the mathematical relationship... ,in The average pore size of the nanopores is expressed in units of 100 nm. ; The unit pore volume of the mesoporous calcium fluoride carrier is expressed in units of 1000 ppm. ; The specific surface area of ​​the mesoporous calcium fluoride carrier is given in units of... .

[0029] Because traditional physical adsorption is insufficient to resist the volume repulsion effect under the thermal cycling environment of underground tunnels (30°C to 90°C), 0.5 wt% of bisphenol A was added to the saturated carrier. Accelerator; utilizing bisphenol The affinity between the promoter and the repellent component leads to the formation of a local enrichment layer at the pore edges of the nanopores. To control the thickness of the dense cross-linked layer formed at the pore openings of the modified mesoporous calcium fluoride powder, a quantitative calibration method based on the hydroxyl content of the carrier surface was used. Thermogravimetric analysis was employed to determine the mass loss rate of the mesoporous calcium fluoride carrier during dehydration at 200℃. To eliminate interference from physically adsorbed water, the specific calibration procedure was set as follows: the carrier sample was placed in an oven at 105℃ for 120 min of isothermal dehydration treatment until the fluctuation of the balance reading was less than 0.001 g; the temperature was then increased to 280℃ at a rate of 5℃ / min. The mass change curve within a specific temperature range of 110℃ to 250℃ was recorded using a data logger. The mass loss of 0.85% to 1.15% measured during this period was defined as the amount of chemically bonded hydroxyl groups removed. Based on this value, the dosage accuracy of the silane coupling agent was calculated according to a molar ratio of 1:1.2 to ensure that the unsaturated double bond grafting density on the support surface remained stable at the level of 1.2 nm⁻². The total molar amount of hydroxyl groups on the surface of the mesoporous calcium fluoride support was calculated based on the loss rate. The upper limit of bisphenol AF promoter addition was determined according to a 1:1 molar ratio of bisphenol AF promoter to hydroxyl groups, and the adsorption amount was controlled to account for a certain percentage of the saturated support mass. In step S2, the silane coupling agent forms an unsaturated double bond graft layer that provides steric hindrance shielding to the bisphenol AF accelerator, restricting its migration into the rubber matrix during the mixing stage. This helps prevent small molecules from reaching 170°C. During the high-pressure vulcanization stage, long-distance diffusion occurs. This scheme adds a 15-minute static adsorption equilibrium process at 45°C before the start of the first-stage vulcanization. This allows the bisphenol AF accelerator to be pre-anchored in situ using a 1.5 nm thick steric barrier formed by the hydroxyl groups at the pores of the carrier and the silane coupling agent. At the moment of injection at 15 MPa pressure, the vulcanizing machine's temperature rise rate is controlled at 0.8°C per second. Utilizing the rapid increase in Mooney viscosity of the fluororubber matrix at 120°C, the effective diffusion radius of the accelerator is locked within an interface layer of 2.5 nm. This results in the in-situ formation of a dense cross-linked layer within a 1 nm to 3 nm space at the edge of the carrier, confining the localized ultrafast cross-linking reaction during the first-stage vulcanization process to the 1 to 3 nm physical space at the nanopore edge. The product is then surface-modified using a silane coupling agent. Vinyltrimethoxysilane or vinyltriethoxysilane is selected as the treatment agent, grafting unsaturated double-bond functional groups onto the outer surface of the mesoporous calcium fluoride carrier. The grafting density of unsaturated double-bond functional groups on the carrier surface is 0.8. Up to 1.5 This method enables modified mesoporous calcium fluoride powder to embed itself into the rubber network as an active crosslinking node, thereby improving the surface hardness of the material and transferring and dispersing stress during dynamic bending through interfacial chemical bonding.

[0030] During the vulcanization process of the composition, bisphenols accumulated at the orifice edges The accelerator induces a local crosslinking reaction at the orifice of the vinylidene fluoride fluorinated rubber matrix, forming a crosslinking layer with a thickness of 1. Up to 3 A dense cross-linked layer; at 25°C, the gaps in the cross-linked network of the dense cross-linked layer are smaller than the molecular dynamic diameter of the repelling component, achieving physical locking; when establishing the engineering parameter mapping relationship of the controlled permeation of the repelling component, a resistance parameter is introduced. Describes the degree to which dense cross-linked layers hinder molecular migration, where To avoid the molecular dynamics diameter of the components, The average free volume distribution of the dense cross-linked layer at 25°C. To avoid the molar volume of the component; the local concentration of the bisphenol AF accelerator in step S2 is adjusted to... Adjust to 0.82 to 0.95 times. Between these points, the diffusion retardation effect generated creates a physical lock-in effect where the network gap is smaller than the molecular dynamic diameter at 25°C. Combined with a thermal history input at a vulcanization temperature of 170°C, the dense cross-linked layer generates an increased permeation gap due to free volume expansion under thermal stress conditions ranging from 30°C to 90°C, thus maintaining a constant release rate of the synthesized capsaicin on the material surface. to Within the temperature range of 30°C to 90°C, the expansion of the free volume of the cross-linked network increases the gaps between the cross-linked networks, allowing the repellent component to penetrate into the material surface in a controlled manner; the specific composition is prepared according to parts by weight, including 100 Vinylidene fluoride fluorinated rubber matrix, 5 Up to 15 Modified mesoporous calcium fluoride powder, 3 up to 8 Acid absorbent, 1 Up to 3 Vulcanizing agent and 0.5 Up to 1.5 Processing aids; the acid scavenger consists of magnesium oxide and calcium hydroxide in a 1:1 mass ratio; the vulcanizing agent is bisphenol A. Processing aids include carnauba wax or calcium stearate; depending on the performance balance requirements, the composition may also include 1 wt% to 5 wt% of reinforcing filler by weight of the matrix, using fluorinated carbon black or precipitated silica to adjust the Mooney viscosity and hardness balance of the composition; the mixing process is carried out in an open mill with a length-to-diameter ratio of 20:1, with the roll temperature set at 40±5℃; first, the vinylidene fluorinated rubber matrix is ​​added and passed through 5 times, followed by the addition of modified mesoporous calcium fluoride powder, acid scavenger, vulcanizing agent and processing aids in batches; a segmented vulcanization procedure is performed to establish the structure of the final product; the first stage of vulcanization is performed at 170℃ and 15MPa for 10 minutes to trigger local ultra-fast crosslinking at the orifice position, forming a molecular gate system; the second stage of vulcanization is performed in a 230℃ oven with 24 hours of circulating air treatment to release residual internal stress and complete the homogenization of the matrix network; the synergistic effect of this process and formulation reduces the risk of voids left after small molecule precipitation, allowing the cable sheath to maintain dielectric barrier properties.

[0031] Example 1: In an underground power tunnel environment with an annual temperature difference of 60°C and the risk of damage from rodents and termites, the repellent component inside the vinylidene fluoride fluorinated rubber matrix tends to migrate towards the material surface due to thermal motion at 90°C. Under these conditions, the modified mesoporous calcium fluoride powder regulates the penetration rate of the repellent component through a dense cross-linked layer located at its pore openings. This dense cross-linked layer is composed of bisphenol A. The accelerator is induced to form during the vulcanization stage. At 25°C, the gap between the cross-linked networks of the dense cross-linked layer is smaller than the molecular dynamic diameter of the repelling component, which manifests as a physical lock-in of the eutectic composed of synthetic capsaicin and denatured bittering agent inside the nanopores.

[0032] When the cable operating temperature increases from 30℃ to 90℃, the vinylidene fluoride fluorinated rubber matrix and the dense cross-linked layer undergo thermal expansion, increasing the gaps in the cross-linked network. The repellent components filling the nanopores penetrate to the material surface, maintaining the concentration of repellent components on the sheath surface. Simultaneously, the vinyl functional groups on the outer surface of the modified mesoporous calcium fluoride powder form interfacial chemical bonds with the vinylidene fluoride fluorinated rubber matrix, dispersing the micro-stress generated by thermal stress and inhibiting stress cracking caused by small molecule aggregation. After undergoing continuous thermal cycling from 30℃ to 90℃ for 180 days, no powdery bloom residue remains on the material surface, and its release rate of synthetic capsaicin remains at 0.5%. Up to 1.2 Within this range, the responsive structure synergistically constructed from modified mesoporous calcium fluoride powder and vinylidene fluorinated rubber matrix achieves a balance between long-lasting bioprotection and material mechanical structural stability.

[0033] Example 2: In the thermal cycling stress test of cable sheaths, a comprehensive verification platform including a zoned temperature-controlled alternating thermal aging chamber and a mechanical excitation device was adopted. The temperature control accuracy of the alternating thermal aging chamber was [insert accuracy here]. At 0.5℃, a mechanical excitation device is used to generate vibration stress simulating harmonics in cable operation. The test environment has a signal-to-noise ratio of 20, actively superimposed at the signal input terminal. Gaussian white noise and frequency of 50 To mitigate power frequency interference, experimental data was acquired using a high-resolution continuous sampling analysis method. The dynamic migration concentration of repellent components on the material surface was monitored to characterize the evolution of protective effectiveness. The sampling period was considered. The design considerations lie in balancing the accuracy of reproducing the release kinetic curve of the repellent component with the data processing load, and determining the sampling period. 24 This value is based on the diffusion coefficient of the repellent component molecules in the vinylidene fluoride fluorinated rubber matrix. It is determined that when the ambient temperature fluctuates between 30℃ and 90℃, the sampling period is... Satisfying the relation ,in To avoid the time required for the core of the modified mesoporous calcium fluoride powder to migrate to the material surface and form a monolayer, the sampling time interval is set to be less than [a certain value]. 10 To avoid distortion of concentration trends caused by signal aliasing.

[0034] Five representative sample groups were prepared for the experiment, including the sample group of this invention. Including 100 Vinylidene fluoride fluorinated rubber matrix and 10 Modified mesoporous calcium fluoride powder, comparative sample group Use bisphenol-free A conventional mesoporous calcium fluoride support treated with an accelerator was used to remove the dense cross-linked layer at the pore openings, compared with the control group. As a lower limit control, the addition amount of modified mesoporous calcium fluoride powder was set at 3%. Comparison sample group As a control for exceeding the upper limit, the addition amount of modified mesoporous calcium fluoride powder was set at 20%. Comparison sample group Using existing technology, 10% of the fluorinated vinylidene rubber matrix is ​​directly added. The free-state repellent component; after experiencing 1000 After alternating thermal cycling aging tests, the release rate of repellent components and the thickness of bloom on the material surface of each sample group at different stages were obtained by mass spectrometry analysis.

[0035] Table 1: Performance data of different groups under thermal stress cycling

[0036]

[0037] Referring to the test results shown in Table 1, the sample group of the present invention During the process of increasing the ambient temperature from 30℃ to 90℃, the release rate fluctuated between 0.3 and 0.5 times. The release rate of control sample C1 (lacking a dense cross-linked layer) and control sample C4 (with directly added repellent components) increased by 5 to 8 times at high temperatures. This abrupt change in release intensity caused a layer of material surface thickness exceeding 50 mm. The blooming layer confirms that the dense cross-linked layer's physical locking effect at the pore openings of the modified mesoporous calcium fluoride powder can suppress the high-temperature piston extrusion effect. Meanwhile, data from sample group C2 show that when the functional component is below 5... Its release rate is below 0.2%. The effective repellency threshold, compared with the data of sample group C3, shows that when the amount added exceeds 15... The tensile strength retention rate of the material deteriorated due to the excessive mineral carrier weakening the stress transfer efficiency of the continuous network of vinylidene fluoride fluorinated rubber matrix. Scanning electron microscopy observation of the micro-section of the S1 sample group in the middle of the experiment showed that a seamless chemical bonded zone was formed at the interface between the modified mesoporous calcium fluoride powder and the vinylidene fluoride fluorinated rubber matrix. This interface structure remained stable under the action of micro-shear force generated by power frequency interference vibration and thermal expansion, preventing moisture from penetrating along the filler interface.

[0038] Example 3: This example combines Figures 1 to 2 A description of a fluororubber-containing rodent-proof and termite-proof cable sheath material composition, such as... Figure 1As shown, the preparation and working mechanism of a fluororubber rodent-proof and termite-proof cable sheath material composition begins with the pretreatment of raw materials. Mesoporous calcium fluoride carriers with pore sizes of 10nm to 30nm and specific surface areas of 150mg to 250mg, along with a repellent component composed of synthetic capsaicin and modified bittersweet, are vacuum-saturated under a negative pressure of 0.01MPa, ensuring a repellent component filling rate greater than 85%. Bisphenol AF is locally adsorbed at the pore openings of the carrier to promote crosslinking initiation sites. Surface grafting modification is then achieved using a silane coupling agent to graft unsaturated double-bond functional groups, introducing modified powder. This modified powder is then mixed with vinylidene fluoride units at a content of 60wt to 80wt and an MS+1 ≥ 25min. The vinylidene fluorinated rubber matrix, combined with acid absorbers, vulcanizing agents, and processing aids, is mixed and dispersed on an open mill at 40°C. After a first-stage vulcanization at 170°C, a vulcanization-induced interfacial reaction occurs locally at the pore openings, resulting in ultrafast crosslinking and interfacial chemical bonding. This generates a dense crosslinked layer, or molecular gate, located at the edge of the carrier pore openings with a thickness of 1nm to 3nm. In its basic state, this structure exhibits a room-temperature physically locked state at 25°C, where the network gaps are smaller than the molecular dynamics diameter to solve the problems of small molecule blooming and precipitation. As the temperature rises, it enters a high-temperature controlled permeation state from 30°C to 90°C. The free volume of the network expands, causing the gaps to increase and driving the trace release of repellent components to maintain concentration. Ultimately, through controlled release, long-term biological protection and anti-fatigue performance are achieved synergistically.

[0039] like Figure 2 As shown, this mechanism involves four interacting entities: the repellent component, the dense cross-linked layer, the gaps in the cross-linked network, and the material surface. At room temperature (25°C), the repellent component attempts to migrate outward, but the gaps in the cross-linked network of the dense cross-linked layer shrink, causing the gaps to be smaller than the molecular dynamic diameter, thus physically locking the repellent component. When the environment changes to a temperature increase of 30°C to 90°C, the dense cross-linked layer undergoes thermal expansion. Due to the expansion of free volume, the gaps in the cross-linked network increase, allowing the repellent component to pass through the gaps and penetrate to the surface in a controlled manner, maintaining a release rate in the range of 0.5 μg to 1.2 μg per square centimeter per day. In the temperature decrease phase, the network shrinks, causing the gaps to decrease again, and the release rate automatically decreases, thus completing the reversible regulation of the release behavior of the repellent component.

[0040] Example 4: During the interface structure calibration process for high-consistency cable sheath composition production batches, the molecular gating system between the vinylidene fluoride fluorinated rubber matrix and the modified mesoporous calcium fluoride powder needs to be determined. The enrichment of promoters at the edges of nanopores to modulate controlled permeation rates, bisphenol The chemisorption of the accelerator on the surface of the mesoporous calcium fluoride support is controlled by the surface hydroxyl density. The surface hydroxyl content is calculated by measuring the dehydration mass loss rate of the mesoporous calcium fluoride support at 200℃, and then determined according to the relationship between hydroxyl groups and bisphenol A. The molar ratio of accelerator to bisphenol was determined. The upper limit of the accelerator's adsorption capacity is set at 0.5. At that time, bisphenol The interfacial wetting layer formed by the accelerator at the orifice generates a local cross-linking driving force; to quantify the physical locking effect of the dense cross-linked layer on the repelling components, an effective resistance parameter is introduced. The effective resistance parameter characterizes the degree to which the dense cross-linked layer hinders molecular migration. The calculation formula is as follows: ,in, The molecular dynamics diameter of the repellent component, in units of , The value represents the average free volume distribution of the dense cross-linked layer at 25°C, in units of... , The molar volume of the component being avoided is expressed in units of... By adjusting bisphenol The local concentration of the accelerator will Adjust to 0.82 to 0.95 times. Between them, the resulting blocking effect is used to achieve physical locking at room temperature.

[0041] Mean free volume distribution of dense cross-linked layer Calibration was performed using dynamic thermodynamic scanning. The specific steps were as follows: the vulcanized sample was scanned at a heating rate of 2℃ / min, and the specific volume change at 25℃ was recorded. The intrinsic volume occupied by the amorphous region (1.35 cm³ / g) was subtracted to obtain the absolute measurement of the free volume. A step-increment model was established, whereby each 5% increase in crosslinking density at the 170℃ vulcanization stage corresponded to... The shrinkage at 25℃ was set at 0.02 cm³ / g. By precisely controlling the adsorption amount of bisphenol AF accelerator within the range of 0.45 g to 0.55 g, this ensured... At room temperature, it is between 0.85 and 0.92 times. The range; regarding the logic for determining process parameters, the initial diffusion activation energy of the eutectic composed of self-synthesized capsaicin and modified bittering in the vinylidene fluorinated rubber matrix was selected for the first-stage vulcanization temperature of 170℃. The exothermic peak temperature of the eutectic was measured to be 195℃ by differential scanning calorimetry. To suppress the increase in internal pore pressure during the first-stage vulcanization process, which could cause the repellent component to break through the interfacial locking layer, the first-stage vulcanization temperature was set 25℃ lower than the exothermic peak temperature. At the same time, the 230℃ environment for the second-stage vulcanization was maintained through 24... Continuous heat treatment brings the crosslinked network of the vinylidene fluorinated rubber matrix to a thermodynamic equilibrium state, at which point the material's compression set decreases from the initial 18.5%. It decreased and stabilized at 8.2. This results in a cable sheath material that is rodent-proof and termite-proof, possessing thermodynamic adaptive adjustment capabilities.

[0042] Example 5: In the continuous production scenario of cable sheath materials, in response to the objective reality that the fluctuation in pore volume of mesoporous calcium fluoride carriers in different batches causes fluctuations in the consistency of repellent component loading, an on-site commissioning procedure based on carrier porosity pre-calibration is adopted. Before the vacuum saturation loading step is started, the unit pore volume of the current batch of mesoporous calcium fluoride carrier is measured. The eutectic mixture of synthetic capsaicin and denatured bittering was mixed at 85°C and maintained for 2 hours. , using 0.01 The negative pressure environment allows the eutectic to enter the nanopores, and the residual pore volume of the powder after loading is measured. And according to the formula Calculate the fill rate, where, For fill rate, The volume is the volume per unit hole, and the unit is... , Residual pore volume, in units of The filling rate is adjusted by regulating the vacuum holding time. Stable at 85 above.

[0043] When the specific surface area of ​​the mesoporous calcium fluoride carrier is 150 Up to 250 When the range varies, the grafting density of unsaturated double-bonded functional groups on the surface is maintained at 0.8. Up to 1.5 Between these steps, a silane coupling agent dosage calibration method based on total surface area mapping was used to determine the amount of vinyltrimethoxysilane added. Set to satisfy the relation ,in, The amount of vinyltrimethoxysilane added, in units of , The specific surface area of ​​the mesoporous calcium fluoride carrier is given in units of... , The mass of the current batch of mesoporous calcium fluoride carrier is expressed in units of... , Target grafting density, in units of , The molar mass of the silane coupling agent is given in units of 1. , The grafting effect was confirmed by measuring the mass loss of the modified powder at 550℃, which allows the modified mesoporous calcium fluoride powder to form interfacial chemical bonds with the vinylidene fluoride fluorinated rubber matrix during vulcanization.

[0044] Example 6: Involving 1000 In large-scale cable sheath material production scenarios, the fluctuation in unit pore volume of mesoporous calcium fluoride carriers across different batches affects the fill rate. For operating conditions deviating from the preset range, a pre-calibration procedure for carrier filling efficiency is adopted, which involves measuring the unit pore volume of the current batch of mesoporous calcium fluoride carrier before vacuum saturation loading. The eutectic mixture of synthetic capsaicin and denatured bittering was mixed at 85°C and maintained for 2 hours. , using 0.01 The negative pressure environment allows the eutectic to enter the nanopores, and the residual pore volume of the powder after loading is measured. And according to the formula Calculate the fill rate, where, For fill rate, The volume is the volume per unit hole, and the unit is... , Residual pore volume, in units of The filling rate is adjusted by regulating the vacuum holding time. Stable at 85 Up to 92 between.

[0045] When the initial Mooney viscosity of the vinylidene fluorinated rubber matrix fluctuates due to production batch changes, a processing method based on thermal history compensation is adopted to achieve the expected local crosslinking density of the composition during a certain vulcanization stage. Specifically, this involves processing at 40°C. Monitoring the scorching behavior of rubber compounds at a rolling mill temperature of 5℃, if the Mooney scorching time of the rubber compound at 121℃ is measured... Deviation 25 Up to 35 The process window was adjusted by modifying the mass ratio of magnesium oxide to calcium hydroxide in the acid absorbent to modify the sulfidation rate, allowing a portion of the sulfidation process to occur at 170℃ and 10℃. Interfacial chemical bonding occurs within a short time, and a thickness of 1 is formed at the pore opening. Up to 3 The dense cross-linked layer maintains the gradient penetration characteristics of the repellent component in environments ranging from 30°C to 90°C.

[0046] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A rodent and termite resistant cable jacket material composition comprising a fluoroelastomer, characterized in that the composition include: Vinylidene fluoride fluorinated rubber matrix and modified mesoporous calcium fluoride powder; The modified mesoporous calcium fluoride powder includes a mesoporous calcium fluoride carrier, a repellent component filling the nanopores of the mesoporous calcium fluoride carrier, and a dense cross-linked layer disposed at the pore opening of the nanopores. Modified mesoporous calcium fluoride powder is prepared through the following steps: Step S1, immerse the mesoporous calcium fluoride carrier in a eutectic mixture composed of synthetic capsaicin and denatured monosodium glutamate in an environment with a vacuum degree of 0.01 MPa, so that the eutectic mixture enters the nanopores with an average pore size of 10 nm to 30 nm and a specific surface area of 100 m2 / g to 300 m2 / g of the mesoporous calcium fluoride carrier, and forms a saturated carrier; to ; Step S2: Add 0.5 wt% of bisphenol AF promoter to the saturated carrier to form a local enrichment layer at the pore edge of the nanopores. Step S3: The product obtained in step S2 is surface modified using a silane coupling agent by grafting unsaturated double bond functional groups onto the outer surface of the mesoporous calcium fluoride support to obtain modified mesoporous calcium fluoride powder. During the vulcanization of the composition, the bisphenol AF accelerator enriched at the pore edges induces a local crosslinking reaction in the vinylidene fluoride fluorinated rubber matrix at the pore openings, forming a dense crosslinked layer. Under 25°C conditions, the gap between the crosslinked network of the dense crosslinked layer is smaller than the molecular dynamic diameter of the repelling component, thereby physically locking the repelling component. In a temperature environment of 30℃ to 90℃, the dense cross-linked layer increases the gap between the cross-linked networks by expanding the free volume of the cross-linked network, so that the repellent component can penetrate into the surface of the vinylidene fluorinated rubber matrix in a controlled manner.

2. A rodent and termite resistant cable jacket material composition of fluoroelastomer according to claim 1, characterized in that, The composition comprises, by weight, 100 phr of vinylidene fluoride fluorinated rubber matrix, 5 to 15 phr of modified mesoporous calcium fluoride powder, 3 to 8 phr of acid scavenger, 1 to 3 phr of vulcanizing agent, and 0.5 to 1.5 phr of processing aid; wherein, in step S1, the loading of the eutectic in the nanopores accounts for more than 85% of the total pore volume of the mesoporous calcium fluoride carrier; and the mass ratio of synthetic capsaicin to modified bittering in the eutectic is 3:

1.

3. A rodent and termite resistant cable jacket material composition of claim 1, wherein, The vinylidene fluorinated rubber matrix is ​​a copolymer of vinylidene fluoride and perfluoropropylene, or a terpolymer of vinylidene fluoride, perfluoropropylene and tetrafluoroethylene; the mass content of vinylidene fluoride units in the vinylidene fluorinated rubber matrix is ​​60wt% to 80wt%, and the Mooney scorch time MS+1 at 121℃ is not less than 25min.

4. A rodent and termite resistant cable jacket material composition of claim 1, wherein, In step S1, the eutectic was prepared by mixing synthetic capsaicin with denatured bittering and heat-treating at 85°C for 2 hours; the average particle size of the mesoporous calcium fluoride support was 0.5 μm to 2.0 μm.

5. The fluororubber rodent-proof and termite-proof cable sheath material composition according to claim 1, characterized in that, The silane coupling agent is vinyltrimethoxysilane or vinyltriethoxysilane; the grafting density of the unsaturated double bond functional group on the surface of the mesoporous calcium fluoride carrier is to .

6. A rodent and termite resistant cable jacket material composition of claim 2, wherein, The acid absorbent is composed of magnesium oxide and calcium hydroxide in a mass ratio of 1:1; the vulcanizing agent is bisphenol AF; and the processing aids include carnauba wax or calcium stearate.

7. The fluororubber rodent-proof and termite-proof cable sheath material composition according to claim 1, characterized in that, The dense cross-linked layer forms an interfacial chemical bond with the vinylidene fluoride fluorinated rubber matrix through unsaturated double bond functional groups, allowing the modified mesoporous calcium fluoride powder to be embedded in the rubber network as an active cross-linking node. This is used to improve the surface hardness of the material while transferring and dispersing the micro-stress during dynamic bending through interfacial chemical bonding.

8. The fluororubber rodent-proof and termite-proof cable sheath material composition according to claim 1, characterized in that, The pore size parameters of the mesoporous calcium fluoride support satisfy the following mathematical relationship: ,in, The average pore size of the nanopores is expressed in units of 100 nm. ; The unit pore volume of the mesoporous calcium fluoride carrier is expressed in units of 1000 ppm. ; The specific surface area of ​​the mesoporous calcium fluoride carrier is given in units of... Mathematical relationships are used to establish the geometric space of nanopores to limit the maximum loading of the eutectic.

9. The fluororubber rodent-proof and termite-proof cable sheath material composition according to claim 2, characterized in that, The composition also includes 1 wt% to 5 wt% of reinforcing filler, which is fluorinated carbon black or precipitated silica, in proportion to the mass of the vinylidene fluorinated rubber matrix, and is used to adjust the Mooney viscosity and hardness balance of the composition.

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